Chemical shifts of common deuterated solvents (TMS is an internal standard).
\\n\\n
Released this past November, the list is based on data collected from the Web of Science and highlights some of the world’s most influential scientific minds by naming the researchers whose publications over the previous decade have included a high number of Highly Cited Papers placing them among the top 1% most-cited.
\\n\\nWe wish to congratulate all of the researchers named and especially our authors on this amazing accomplishment! We are happy and proud to share in their success!
\\n"}]',published:!0,mainMedia:null},components:[{type:"htmlEditorComponent",content:'IntechOpen is proud to announce that 179 of our authors have made the Clarivate™ Highly Cited Researchers List for 2020, ranking them among the top 1% most-cited.
\n\nThroughout the years, the list has named a total of 252 IntechOpen authors as Highly Cited. Of those researchers, 69 have been featured on the list multiple times.
\n\n\n\nReleased this past November, the list is based on data collected from the Web of Science and highlights some of the world’s most influential scientific minds by naming the researchers whose publications over the previous decade have included a high number of Highly Cited Papers placing them among the top 1% most-cited.
\n\nWe wish to congratulate all of the researchers named and especially our authors on this amazing accomplishment! We are happy and proud to share in their success!
\n'}],latestNews:[{slug:"stanford-university-identifies-top-2-scientists-over-1-000-are-intechopen-authors-and-editors-20210122",title:"Stanford University Identifies Top 2% Scientists, Over 1,000 are IntechOpen Authors and Editors"},{slug:"intechopen-authors-included-in-the-highly-cited-researchers-list-for-2020-20210121",title:"IntechOpen Authors Included in the Highly Cited Researchers List for 2020"},{slug:"intechopen-maintains-position-as-the-world-s-largest-oa-book-publisher-20201218",title:"IntechOpen Maintains Position as the World’s Largest OA Book Publisher"},{slug:"all-intechopen-books-available-on-perlego-20201215",title:"All IntechOpen Books Available on Perlego"},{slug:"oiv-awards-recognizes-intechopen-s-editors-20201127",title:"OIV Awards Recognizes IntechOpen's Editors"},{slug:"intechopen-joins-crossref-s-initiative-for-open-abstracts-i4oa-to-boost-the-discovery-of-research-20201005",title:"IntechOpen joins Crossref's Initiative for Open Abstracts (I4OA) to Boost the Discovery of Research"},{slug:"intechopen-hits-milestone-5-000-open-access-books-published-20200908",title:"IntechOpen hits milestone: 5,000 Open Access books published!"},{slug:"intechopen-books-hosted-on-the-mathworks-book-program-20200819",title:"IntechOpen Books Hosted on the MathWorks Book Program"}]},book:{item:{type:"book",id:"9982",leadTitle:null,fullTitle:"Cosmology 2020 - The Current State",title:"Cosmology 2020",subtitle:"The Current State",reviewType:"peer-reviewed",abstract:"Cosmology 2020 – The Current State offers the reader several fresh ideas on this topic. The first chapter presents an argument that, both in theory and in reality, one cannot ignore the microscopic world to concentrate on the Universe at only the galactic level. Then we have several chapters presenting new explanations for dark energy and dark matter based on reasonable physics at the atomic level. We cover the beginnings of artificial intelligence to model a cosmological phenomenon and a chapter pointing out that better results can be culled from SNe Ia and HII data when appropriate computerised analyses are applied. We think this book will add some new ideas to the libraries of many cosmologists and astrophysicists.",isbn:"978-1-83968-268-1",printIsbn:"978-1-83968-267-4",pdfIsbn:"978-1-83968-269-8",doi:"10.5772/intechopen.87805",price:119,priceEur:129,priceUsd:155,slug:"cosmology-2020-the-current-state",numberOfPages:114,isOpenForSubmission:!1,isInWos:1,hash:"35188e364272b0f50d145f33b01931fa",bookSignature:"Michael L. Smith",publishedDate:"May 27th 2020",coverURL:"https://cdn.intechopen.com/books/images_new/9982.jpg",numberOfDownloads:1590,numberOfWosCitations:2,numberOfCrossrefCitations:3,numberOfDimensionsCitations:4,hasAltmetrics:1,numberOfTotalCitations:9,isAvailableForWebshopOrdering:!0,dateEndFirstStepPublish:"November 7th 2019",dateEndSecondStepPublish:"November 28th 2019",dateEndThirdStepPublish:"January 27th 2020",dateEndFourthStepPublish:"April 16th 2020",dateEndFifthStepPublish:"June 15th 2020",currentStepOfPublishingProcess:5,indexedIn:"1,2,3,4,5,6,7",editedByType:"Edited by",kuFlag:!1,editors:[{id:"59479",title:"Dr.",name:"Michael L.",middleName:null,surname:"Smith",slug:"michael-l.-smith",fullName:"Michael L. Smith",profilePictureURL:"https://mts.intechopen.com/storage/users/59479/images/system/59479.png",biography:"Dr. Michael Smith has decades of experience in computerized data analysis and has co-authored many articles on several novel ideas in cosmology and fundamental physics. Mike has analyzed many variations of ΛCDM cosmology with the FLRW model using supernovae Ia, II, and gamma-ray burst data. He also co-authored one of the first articles on polytropic cosmology published by IntechOpen. In addition, he recently developed a more general version of the Einstein field equation. After many years working as a consultant for both the pharmaceutical and energy industries he has retired to spend some time investigating the properties of the FLRW model. He is currently interested in the real meanings of the spacetime parameters, K and Ωk, and is also writing programs to better analyze SNe Ia data and will make these Python 3 versions available to the public.",institutionString:"Smart Formulations, Inc. - Retired President",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"2",totalChapterViews:"0",totalEditedBooks:"1",institution:null}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,coeditorOne:null,coeditorTwo:null,coeditorThree:null,coeditorFour:null,coeditorFive:null,topics:[{id:"633",title:"Physical Cosmology",slug:"cosmology-physical-cosmology"}],chapters:[{id:"71544",title:"Rethinking “Dark Matter” within the Epistemologically Different World (EDW) Perspective",doi:"10.5772/intechopen.91454",slug:"rethinking-dark-matter-within-the-epistemologically-different-world-edw-perspective",totalDownloads:255,totalCrossrefCites:1,totalDimensionsCites:1,signatures:"Gabriel Vacariu and Mihai Vacariu",downloadPdfUrl:"/chapter/pdf-download/71544",previewPdfUrl:"/chapter/pdf-preview/71544",authors:[{id:"315069",title:"Prof.",name:"Gabriel",surname:"Vacariu",slug:"gabriel-vacariu",fullName:"Gabriel Vacariu"},{id:"315070",title:"Dr.",name:"Mihai",surname:"Vacariu",slug:"mihai-vacariu",fullName:"Mihai Vacariu"}],corrections:null},{id:"71996",title:"Bayesian Deep Learning for Dark Energy",doi:"10.5772/intechopen.91466",slug:"bayesian-deep-learning-for-dark-energy",totalDownloads:294,totalCrossrefCites:0,totalDimensionsCites:1,signatures:"Celia Escamilla-Rivera",downloadPdfUrl:"/chapter/pdf-download/71996",previewPdfUrl:"/chapter/pdf-preview/71996",authors:[{id:"315831",title:"Prof.",name:"Celia",surname:"Escamilla-Rivera",slug:"celia-escamilla-rivera",fullName:"Celia Escamilla-Rivera"}],corrections:null},{id:"71170",title:"The Tension over the Hubble-Lemaitre Constant",doi:"10.5772/intechopen.91266",slug:"the-tension-over-the-hubble-lemaitre-constant",totalDownloads:271,totalCrossrefCites:0,totalDimensionsCites:0,signatures:"Michael L. Smith and Ahmet M. Öztaș",downloadPdfUrl:"/chapter/pdf-download/71170",previewPdfUrl:"/chapter/pdf-preview/71170",authors:[{id:"59479",title:"Dr.",name:"Michael L.",surname:"Smith",slug:"michael-l.-smith",fullName:"Michael L. Smith"},{id:"59581",title:"Prof.",name:"Ahmet M.",surname:"Öztaș",slug:"ahmet-m.-oztas",fullName:"Ahmet M. Öztaș"}],corrections:null},{id:"71239",title:"Nature of Dark Energy",doi:"10.5772/intechopen.91442",slug:"nature-of-dark-energy",totalDownloads:255,totalCrossrefCites:0,totalDimensionsCites:0,signatures:"Jan Olof Stenflo",downloadPdfUrl:"/chapter/pdf-download/71239",previewPdfUrl:"/chapter/pdf-preview/71239",authors:[{id:"315797",title:"Emeritus Prof.",name:"Jan",surname:"Stenflo",slug:"jan-stenflo",fullName:"Jan Stenflo"}],corrections:null},{id:"71023",title:"Primary Role of the Quantum Electromagnetic Vacuum in Gravitation and Cosmology",doi:"10.5772/intechopen.91157",slug:"primary-role-of-the-quantum-electromagnetic-vacuum-in-gravitation-and-cosmology",totalDownloads:225,totalCrossrefCites:1,totalDimensionsCites:1,signatures:"Constantin Meis",downloadPdfUrl:"/chapter/pdf-download/71023",previewPdfUrl:"/chapter/pdf-preview/71023",authors:[{id:"302026",title:"Prof.",name:"Constantin",surname:"Meis",slug:"constantin-meis",fullName:"Constantin Meis"}],corrections:null},{id:"71525",title:"Dark Matter as Cold Atomic Hydrogen in Its Lower Ground State",doi:"10.5772/intechopen.91690",slug:"dark-matter-as-cold-atomic-hydrogen-in-its-lower-ground-state",totalDownloads:292,totalCrossrefCites:1,totalDimensionsCites:1,signatures:"Eugene Terry Tatum",downloadPdfUrl:"/chapter/pdf-download/71525",previewPdfUrl:"/chapter/pdf-preview/71525",authors:[{id:"261441",title:"Dr.",name:"Eugene",surname:"Tatum",slug:"eugene-tatum",fullName:"Eugene Tatum"}],corrections:null}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}},relatedBooks:[{type:"book",id:"3211",title:"Open Questions in Cosmology",subtitle:null,isOpenForSubmission:!1,hash:"6e4e21582afb611a1552d8493d66f82c",slug:"open-questions-in-cosmology",bookSignature:"Gonzalo J. Olmo",coverURL:"https://cdn.intechopen.com/books/images_new/3211.jpg",editedByType:"Edited by",editors:[{id:"61779",title:"Dr.",name:"Gonzalo J.",surname:"Olmo",slug:"gonzalo-j.-olmo",fullName:"Gonzalo J. Olmo"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1374",title:"Aspects of Today's Cosmology",subtitle:null,isOpenForSubmission:!1,hash:"6f152698fbe6139a2fe31a70ec8668d0",slug:"aspects-of-today-s-cosmology",bookSignature:"Antonio Alfonso-Faus",coverURL:"https://cdn.intechopen.com/books/images_new/1374.jpg",editedByType:"Edited by",editors:[{id:"62140",title:"Prof.",name:"Antonio",surname:"Alfonso-Faus",slug:"antonio-alfonso-faus",fullName:"Antonio Alfonso-Faus"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1680",title:"Space Science",subtitle:null,isOpenForSubmission:!1,hash:"2429d8599f5c44daca7b0d12f3d70bb8",slug:"space-science",bookSignature:"Herman J. Mosquera Cuesta",coverURL:"https://cdn.intechopen.com/books/images_new/1680.jpg",editedByType:"Edited by",editors:[{id:"15074",title:"Dr.",name:"Herman J.",surname:"Mosquera Cuesta",slug:"herman-j.-mosquera-cuesta",fullName:"Herman J. Mosquera Cuesta"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"400",title:"Advances in Modern Cosmology",subtitle:null,isOpenForSubmission:!1,hash:"042beba0021ef61f561bf65a1fb2b115",slug:"advances-in-modern-cosmology",bookSignature:"Adnan Ghribi",coverURL:"https://cdn.intechopen.com/books/images_new/400.jpg",editedByType:"Edited by",editors:[{id:"58295",title:"Dr.",name:"Adnan",surname:"Ghribi",slug:"adnan-ghribi",fullName:"Adnan Ghribi"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"7389",title:"Redefining Standard Model Cosmology",subtitle:null,isOpenForSubmission:!1,hash:"25572d83043224835eabdf8632fc64ed",slug:"redefining-standard-model-cosmology",bookSignature:"Brian Albert Robson",coverURL:"https://cdn.intechopen.com/books/images_new/7389.jpg",editedByType:"Edited by",editors:[{id:"102886",title:"Prof.",name:"Brian Albert",surname:"Robson",slug:"brian-albert-robson",fullName:"Brian Albert Robson"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"6693",title:"Essentials on Dark Matter",subtitle:null,isOpenForSubmission:!1,hash:"7b9819be21ab94f8d165da9b5531b6bc",slug:"essentials-on-dark-matter",bookSignature:"Abraão Jessé Capistrano de Souza",coverURL:"https://cdn.intechopen.com/books/images_new/6693.jpg",editedByType:"Edited by",editors:[{id:"52362",title:"Dr.",name:"Abraao",surname:"Capistrano",slug:"abraao-capistrano",fullName:"Abraao Capistrano"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1591",title:"Infrared Spectroscopy",subtitle:"Materials Science, Engineering and Technology",isOpenForSubmission:!1,hash:"99b4b7b71a8caeb693ed762b40b017f4",slug:"infrared-spectroscopy-materials-science-engineering-and-technology",bookSignature:"Theophile Theophanides",coverURL:"https://cdn.intechopen.com/books/images_new/1591.jpg",editedByType:"Edited by",editors:[{id:"37194",title:"Dr.",name:"Theophanides",surname:"Theophile",slug:"theophanides-theophile",fullName:"Theophanides Theophile"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3092",title:"Anopheles mosquitoes",subtitle:"New insights into malaria vectors",isOpenForSubmission:!1,hash:"c9e622485316d5e296288bf24d2b0d64",slug:"anopheles-mosquitoes-new-insights-into-malaria-vectors",bookSignature:"Sylvie Manguin",coverURL:"https://cdn.intechopen.com/books/images_new/3092.jpg",editedByType:"Edited by",editors:[{id:"50017",title:"Prof.",name:"Sylvie",surname:"Manguin",slug:"sylvie-manguin",fullName:"Sylvie Manguin"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3161",title:"Frontiers in Guided Wave Optics and Optoelectronics",subtitle:null,isOpenForSubmission:!1,hash:"deb44e9c99f82bbce1083abea743146c",slug:"frontiers-in-guided-wave-optics-and-optoelectronics",bookSignature:"Bishnu Pal",coverURL:"https://cdn.intechopen.com/books/images_new/3161.jpg",editedByType:"Edited by",editors:[{id:"4782",title:"Prof.",name:"Bishnu",surname:"Pal",slug:"bishnu-pal",fullName:"Bishnu Pal"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"72",title:"Ionic Liquids",subtitle:"Theory, Properties, New Approaches",isOpenForSubmission:!1,hash:"d94ffa3cfa10505e3b1d676d46fcd3f5",slug:"ionic-liquids-theory-properties-new-approaches",bookSignature:"Alexander Kokorin",coverURL:"https://cdn.intechopen.com/books/images_new/72.jpg",editedByType:"Edited by",editors:[{id:"19816",title:"Prof.",name:"Alexander",surname:"Kokorin",slug:"alexander-kokorin",fullName:"Alexander Kokorin"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}],ofsBooks:[]},correction:{item:{id:"72959",slug:"erratum-driving-control-technologies-of-new-high-efficient-motors",title:"Erratum - Driving Control Technologies of New High-Efficient Motors",doi:null,correctionPDFUrl:"https://cdn.intechopen.com/pdfs/72959.pdf",downloadPdfUrl:"/chapter/pdf-download/72959",previewPdfUrl:"/chapter/pdf-preview/72959",totalDownloads:null,totalCrossrefCites:null,bibtexUrl:"/chapter/bibtex/72959",risUrl:"/chapter/ris/72959",chapter:{id:"68411",slug:"driving-control-technologies-of-new-high-efficient-motors",signatures:"Chang-Ming Liaw, Min-Ze Lu, Ping-Hong Jhou and Kuan-Yu Chou",dateSubmitted:"April 1st 2019",dateReviewed:"July 2nd 2019",datePrePublished:"August 22nd 2019",datePublished:"March 25th 2020",book:{id:"9290",title:"Applied Electromechanical Devices and Machines for Electric Mobility Solutions",subtitle:null,fullTitle:"Applied Electromechanical Devices and Machines for Electric Mobility Solutions",slug:"applied-electromechanical-devices-and-machines-for-electric-mobility-solutions",publishedDate:"March 25th 2020",bookSignature:"Adel El-Shahat and Mircea Ruba",coverURL:"https://cdn.intechopen.com/books/images_new/9290.jpg",licenceType:"CC BY 3.0",editedByType:"Edited by",editors:[{id:"193331",title:"Dr.",name:"Adel",middleName:null,surname:"El-Shahat",slug:"adel-el-shahat",fullName:"Adel El-Shahat"}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}},authors:[{id:"37616",title:"Prof.",name:"Chang-Ming",middleName:null,surname:"Liaw",fullName:"Chang-Ming Liaw",slug:"chang-ming-liaw",email:"cmliaw@ee.nthu.edu.tw",position:null,institution:null},{id:"180324",title:"Dr.",name:"Kai-Wei",middleName:null,surname:"Hu",fullName:"Kai-Wei Hu",slug:"kai-wei-hu",email:"kaiweihu@hotmail.com.tw",position:null,institution:{name:"National Tsing Hua University",institutionURL:null,country:{name:"Taiwan"}}},{id:"308019",title:"MSc.",name:"Jia-Hsiang",middleName:null,surname:"Zhuang",fullName:"Jia-Hsiang Zhuang",slug:"jia-hsiang-zhuang",email:"abc0929352983@yahoo.com.tw",position:null,institution:{name:"National Tsing Hua University",institutionURL:null,country:{name:"Taiwan"}}},{id:"308021",title:"MSc.",name:"Shih-Wei",middleName:null,surname:"Su",fullName:"Shih-Wei Su",slug:"shih-wei-su",email:"nthu18356743@gmail.com",position:null,institution:{name:"National Tsing Hua University",institutionURL:null,country:{name:"Taiwan"}}}]}},chapter:{id:"68411",slug:"driving-control-technologies-of-new-high-efficient-motors",signatures:"Chang-Ming Liaw, Min-Ze Lu, Ping-Hong Jhou and Kuan-Yu Chou",dateSubmitted:"April 1st 2019",dateReviewed:"July 2nd 2019",datePrePublished:"August 22nd 2019",datePublished:"March 25th 2020",book:{id:"9290",title:"Applied Electromechanical Devices and Machines for Electric Mobility Solutions",subtitle:null,fullTitle:"Applied Electromechanical Devices and Machines for Electric Mobility Solutions",slug:"applied-electromechanical-devices-and-machines-for-electric-mobility-solutions",publishedDate:"March 25th 2020",bookSignature:"Adel El-Shahat and Mircea Ruba",coverURL:"https://cdn.intechopen.com/books/images_new/9290.jpg",licenceType:"CC BY 3.0",editedByType:"Edited by",editors:[{id:"193331",title:"Dr.",name:"Adel",middleName:null,surname:"El-Shahat",slug:"adel-el-shahat",fullName:"Adel El-Shahat"}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}},authors:[{id:"37616",title:"Prof.",name:"Chang-Ming",middleName:null,surname:"Liaw",fullName:"Chang-Ming Liaw",slug:"chang-ming-liaw",email:"cmliaw@ee.nthu.edu.tw",position:null,institution:null},{id:"180324",title:"Dr.",name:"Kai-Wei",middleName:null,surname:"Hu",fullName:"Kai-Wei Hu",slug:"kai-wei-hu",email:"kaiweihu@hotmail.com.tw",position:null,institution:{name:"National Tsing Hua University",institutionURL:null,country:{name:"Taiwan"}}},{id:"308019",title:"MSc.",name:"Jia-Hsiang",middleName:null,surname:"Zhuang",fullName:"Jia-Hsiang Zhuang",slug:"jia-hsiang-zhuang",email:"abc0929352983@yahoo.com.tw",position:null,institution:{name:"National Tsing Hua University",institutionURL:null,country:{name:"Taiwan"}}},{id:"308021",title:"MSc.",name:"Shih-Wei",middleName:null,surname:"Su",fullName:"Shih-Wei Su",slug:"shih-wei-su",email:"nthu18356743@gmail.com",position:null,institution:{name:"National Tsing Hua University",institutionURL:null,country:{name:"Taiwan"}}}]},book:{id:"9290",title:"Applied Electromechanical Devices and Machines for Electric Mobility Solutions",subtitle:null,fullTitle:"Applied Electromechanical Devices and Machines for Electric Mobility Solutions",slug:"applied-electromechanical-devices-and-machines-for-electric-mobility-solutions",publishedDate:"March 25th 2020",bookSignature:"Adel El-Shahat and Mircea Ruba",coverURL:"https://cdn.intechopen.com/books/images_new/9290.jpg",licenceType:"CC BY 3.0",editedByType:"Edited by",editors:[{id:"193331",title:"Dr.",name:"Adel",middleName:null,surname:"El-Shahat",slug:"adel-el-shahat",fullName:"Adel El-Shahat"}],productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"}}},ofsBook:{item:{type:"book",id:"10252",leadTitle:null,title:"Chlamydomonas - Model Organism and New Directions",subtitle:null,reviewType:"peer-reviewed",abstract:"\r\n\tThe green unicellular alga Chlamydomonas is a favorite model organism namely due to ease of culturing, sequenced genome and existence of a powerful tool for genetic manipulation. The possession of flagella is also not negligible advantage as they serves as a model in the research of cilia and ciliary diseases. Chlamydomonas cultures can be also easily synchronized under physiological conditions without any inhibitors. Research of Chlamydomonas has expanded enormously, namely because of above mentioned reasons.
\r\n\r\n\tThe book Chlamydomonas – Model Organism and New Directions covers major aspects of microalgae physiology and possible applications in the sphere of biotechnology. This book gives a comprehensive overview of what is known about Chlamydomonas ultrastructure, growth, reproduction, cell cycle regulation, photosynthesis, metabolism, plastids, flagella, motility, heat and circadian control, acclimation, genetics and culturing. It is focused on new directions in the research of Chlamydomonas, developing systems and technologies, novel studies and possible applications in biotechnology.
\r\n\r\n\t
\r\n\tThis volume presents the multifaceted aspects and should allow readers at all levels an entry into the exiting world of Chlamydomonas research.
\r\n\t
The phytochemicals rich in plants have shown to be beneficial for prevention of diseases as well as long-term health. Plants are generally consumed as sources of essential compounds such as saccharides, coumarins, lignans, flavonoids, terpenoids, and steroids. The health benefits and the composition from plant have been described more and more in the literature. Because of the complexity of plant chemical constituents, pure phytochemicals must to be obtained via extraction and isolation before structure identification, bioactivity screening, and so on. In recent years, new technologies and methods of extraction occurred, which accelerate the extraction and analysis of phytochemicals.
Extraction is the first step of phytochemistry research, which is also the necessary work before the isolation of effective constituents. The purpose of extraction is to get the objective chemical constituents to the utmost extent and avoid or reduce the solution of unwanted constituents.
The separation of phytochemicals is a process of isolating the constituents of plant extracts or effective parts one by one and purifying them into monomer compounds by physical and chemical methods. Classical isolation methods, including solvent extraction, precipitation, crystallization, fractional distillation, salting-out, and dialysis, are still used commonly at present. On the other hand, modern separation technologies such as column chromatography, high performance liquid chromatography, ultrafiltration, and high performance liquid drop countercurrent chromatography also play an important role in the separation of phytochemicals [1, 2, 3].
The chemical structures of plant compounds must be identified, which may provide the necessary basis for further study on the bioactivities, structure-activity relationships, metabolisms in vivo, structural modification, and synthesis of the active phytochemicals.
The structural studies are often difficult to carry out with classical chemical methods, such as chemical degradation and derivative synthesis, because of the minute amount of compound isolated from plants. Therefore, spectral analysis is mainly used. That is, consuming sample as little as possible to obtained structural information as much as possible by measuring and analyzing various spectra [4].
Solvent extraction is the commonest method to extract plant material. The main purpose is to select the suitable solvent to extract target plant materials efficiently. During the extraction, the solvent has to diffuse into the cell membrane in the first instance, in the following step it has to dissolve the solutes, then intracellular and extracellular concentration difference is formed, and finally it has to diffuse out of the cells enriched in the extracted solutes [5].
Selecting suitable solvents is the key of the solvent extraction method. Using a solvent of an appropriate polarity according to the principle of “like dissolves like” is the main point to select solvent. Thus, hydrophilic solvents are used to solubilize hydrophilic chemical constituents and vice versa. The hydrophilicity or lipophilicity of solvents and chemical constituents could be predicted by polarity. The plant compounds, such as terpenoids and steroids, possess low polarity, and could be dissolved into lipophilic solvents such as chloroform and ether, while chemical constituents, such as carbohydrates and amino acids, possess rather high polarity and could be dissolved into water and aqueous ethanol.
Solvents commonly used for extracting chemical constituents of plants are in the order of weak to strong polarity as follows: petroleum ether < carbon tetrachloride < benzene < dichloromethane < chloroform < ether < ethyl acetate < n-butanol < acetone < ethanol < methanol < water.
Water is a cheap, easy to get, and nontoxic solvent with strong polarity. It could be used to extract phytochemicals with strong polarity, such as inorganic salts, saccharides, amino acids, tannins, proteins, organic acid salts, alkaloid salts, and glycosides. Acid or alkaline water is applied sometimes to increase the solubility of certain specific components. Acid water could extract alkaline materials, such as alkaloids, via the formation of salts. Similarly, organic acids, anthraquinoids, flavonoids, coumarinoids, phenols, and other acidic materials could be extracted via the formation of salts. The disadvantage to extract chemical constituents with water is that the aqueous extract is easy to go moldy, so difficult to preserve. Additionally, water possesses high boiling point, and the water extract needs to be concentrated for a rather long time. Furthermore, the water extract contains many impurities such as proteins, pectins, tannins, mucilages, and inorganic salts, which make the extraction of target components difficult.
Hydrophilic organic solvents are strong-polarity and water miscible, such as methanol, ethanol, and acetone. Ethanol is the most commonly used hydrophilic organic solvent. Chemical constituents could be extracted by ethanol of different concentrations according to their properties. Furthermore, ethanol is inexpensive, safe, and concentrated easily. Additionally, ethanol extract is not readily moldy and glycosides are hard to be hydrolyzed in ethanol extract. Thus, ethanol is one of the most commonly used solvents in laboratories and industrial production. Methanol possesses similar property to ethanol and lower boiling point. However, methanol has rather strong toxicity, so we have to pay attention to safety when it has to be used. Acetone is a good solvent to extract lipid-soluble chemical constituents. However, acetone is easy to volatilize and flame, and it possesses certain toxicity.
Petroleum ether, benzene, chloroform, ether, ethyl acetate, dichloroform, and so on are lipophilic organic solvents and are not miscible with water. They could be applied to extract lipophilic components, such as volatile oils, fats, chlorophyll, lactones, phytosterols, some alkaloids and some aglycones (aglycones of flavonoids, anthraquinoids, steroids, and so on). These solvents possess low boiling points and are easy to concentrate. However, strong-volatility, large loss, flammability, toxicity, and high price are their disadvantages. Additionally, they are difficult to permeate into plant cell tissues.
Solvent extraction methods could be classified as cold extraction and hot extraction roughly by whether heating or not.
It is a method to dissolve out phytochemicals with appropriate solvents at room or low temperatures (<80°C). It is suitable to extract phytochemicals easily to be destroyed at high temperature. The plants with abundant starches, pectins, gums, or mucilages could also be extracted with this method. Firstly, plant powder or pieces should be loaded in the adequate container, and then the suitable solvents (water, ethanol, aqueous ethanol, and so on) are added into it to immerse the material for the given length of time. Discontinuous stirring or shaking during the process could accelerate dissolution rate. The immersion method is simple but inefficient, and the extraction ratio is also low. Furthermore, aqueous extract is easy to go moldy, so addition of appropriate preservatives is necessary.
The coarse particles of plants should be loaded in percolation apparatus and immersed with suitable solvent for 24–48 h, then collect the percolates at the bottom of percolation apparatus. New solvent should be added at the top of percolation apparatus constantly during the percolation process. It possesses higher efficiency than the immersion method because of the sustained concentration difference during the process. However, this procedure is complex and consumes rather much solvent and long time.
Load short segments, thin pieces, or coarse powder into an appropriate container, add water, and heat it to boiling; the components are then extracted. It is easy to operate; most of the constituents could be extracted in various degrees. Nevertheless, rather much nontargeted components could also be extracted, and it is not suitable to the extraction of volatile compounds and thermal unstable compounds. Furthermore, it is not suitable to extract plants with lots of starches [6].
It is a method to extract plant chemical constituents by organic solvent using heating and refluxing. Refluxing apparatus is necessary so as not to waste solvents, and the toxicity to operators or ruin the environment is deduced. It is applicable to extraction of lipophilic phytochemicals, such as steroids, anthraquinoids, and terpenoids. It is an extraction method of high efficiency but complex, and consumes much more solvent. This method is not applicable to extract thermal unstable chemical constituents because of long time heating.
It is a method developed based on the refluxing method. Soxhlet extractor is the most frequently used constant refluxing apparatus. This method avoids disadvantages of consuming too much solvent and complex operation. However, as a refluxing method, constant refluxing method is not applicable to extract thermally unstable compound either because of long time heating.
In the supercritical state, the supercritical fluid is contacted with the plant tissues. By controlling different temperatures, pressures and different kinds and contents of entrainers, the supercritical fluid can selectively extract the components of different polarities, boiling points, and molecular weights successively. This method is called the supercritical fluid extraction (SFE) method [7].
The critical point of a pure substance is defined as the highest temperature and pressure at which the substance can exist in vapor-liquid equilibrium. At temperatures and pressures above this point, a single homogeneous fluid is formed, which is known as supercritical fluid (SF). SF is heavy like liquid and has low viscosity like gas meanwhile. SF possesses rather large diffusion coefficient and could dissolve many compounds well. A number of materials could be used as SFs, such as ammonia, ethane, difluoro-dichloromethane, heptane, and so on, while the most widely used SF is CO2. The critical temperature of CO2 (Tc = 31.26°C) is close to room temperature, and the critical pressure (Pc = 7.2 MPa) is not too high. CO2 also has a series of other advantages, such as nontoxicity, odorless, nonflammable, chemical stability, and low cost, which allowed it to be the most commonly used solvent in SFE. CO2 is a nonpolar substance and applicable to extract lipophilic compounds. However, its dissolvability is weak compared to strong polar substances. Hence, entrainers are always added to improve the solubility of SF CO2 during the extraction of polar compounds. Entrainers, which are added into SF little, could enhance solubility of SF significantly. The commonly used entrainers are methanol, ethanol, water, acetone, ethyl acetate, acetonitrile, and so on.
The extraction of nonpolar and medium-polar components by SFE can avoid the sample loss and environmental pollution caused by solvent recovery in traditional extraction methods, especially for the extraction of volatile compounds with thermal instability.
The biggest advantage of SFE is that it can be performed at near-room temperature, and almost all the active ingredients in the product can be retained. There is no residual organic solvent in the process. The product has high purity and high yield. Additionally, the operation is simple and energy saving.
Compared with other conventional separation methods, SFE possesses the following advantages: (1) No residual organic solvents, fast extraction speed, simple process, high yield, and easy operation; (2) no flammable and explosive dangers, no environmental pollution. Low extraction temperature, suitable for the extraction of thermal unstable components; (3) the dissolution properties of SF are easy to improve, only the pressure needs to be changed at a certain temperature; (4) entrainers can be added to change the polarity of the extraction medium to extract polar substances; extraction medium can be recycled with low cost; (5) it could be applied combined with other chromatographic techniques, such as GC, IR, GC–MS, and HPLC, to extract, separate, and determine phytochemicals efficiently and quickly, so as to achieve the integration of extraction and quality analysis. However, supercritical extraction has some limitations: strong solubility of fat-soluble components, weak solubility of water-soluble components, high cost of equipment, resulting in higher product costs, and cleaning equipment is difficult.
Supercritical fluid extraction (SFE) technology has achieved gratifying results in the fields of medicine, chemical, food, light industry, and environmental protection. Especially, it has been widely used in phytochemical extraction field, such as the extraction of alkaloids, volatile oils, phenylpropanoids, flavonoids, organic acids, glycosides, terpenoids, and so on.
It is a method of solvent extraction assisted by ultrasound. Ultrasonic wave is a kind of elastic mechanical vibration wave. The vibration frequency is as high as 20 KHz in elastic medium. The ultrasonic wave could vibrate the liquid medium. When the vibration is sparse, many small holes are formed in the medium. The instantaneous closure of these small holes can cause a pressure of up to thousands of atmospheric pressures. At the same time, the local temperature can rise to 1000°C. It can cause instantaneous rupture of the cell wall of plants and the whole organism, and make the solvent permeate into the cells of plants. This accelerates the dissolution of active ingredients in plants into solvents. Ultrasonic wave extraction could shorten the extraction time and improve the extraction efficiency, but could not change the structures of chemical constituents meanwhile.
Ultrasonic extraction technology has been widely used in the extraction of natural products in recent years, for example, extraction of soy isoflavones; see [8].
Microwave refers to the electromagnetic wave whose wavelength is in the range of 0.1–100 cm (the corresponding frequency is 300–300,000 MHz), which is between infrared and radio waves. Polar molecules can absorb microwave energy, then release energy in the form of thermal energy, which makes the temperature inside the medium rise rapidly, causes the rather high pressure inside, and then the components flow out and dissolve in the solvent. On the other hand, the electromagnetic field produced by microwave can make some components diffuse to the interface of the extraction solvent, accelerating their thermal movement, which not only improves the extraction efficiency but also reduces the extraction temperature [9].
Microwave-assisted extraction has the advantages of less decomposition of chemical constituents, shorter time, lower energy consumption and less environmental pollution. Microwave-assisted extraction has been widely used in a series of fields of perfume, condiments, natural pigments, herbal medicine, cosmetics, soil and environmental analysis, and so on. In China, microwave-assisted extraction technology has been used in hundreds of Chinese herbal medicine extraction, such as Pueraria lobata, Panax notoginseng, Ginkgo, and so on, for example, the extraction of tea polyphenols and tea caffeine from green tea leaves; see [10].
Steam distillation is suitable for the extraction of volatile components which can be distilled with steam without being destroyed and are insoluble in water. These compounds’ boiling points of are mostly higher than 100°C, and they possess certain vapor pressures at about 100°C. The principle of steam distillation is that the vapor pressure of each component is equal to that of their pure state, while the existence of another liquid does not affect their vapor pressure. The total vapor pressure of the mixing system is equal to the sum of the vapor pressures of the two components. Because the total vapor pressure of the system is higher than that of any single component, so the boiling point of the mixture is lower than that of any component. It is mainly used to extract volatile oils, some alkaloids, and phenolic substances of small molecules from plants.
The process that solid material converts into steam directly without melting after heating is called sublimation. The phenomenon that steam condenses into solid after cooling is called deposition. Some natural chemicals have sublimation properties, which can be extracted directly with the sublimation method, for example, the extraction of camphor from camphor wood and caffeine from tea. In addition, some small molecular alkaloids, coumarins, organic acids, and other components also have sublimation properties, such as aesculetin and benzoic acid. However, it is easy to carbonize natural products because of long heating time. The volatile tar-like substances often adhere to sublimates, which are difficult to remove and often accompanied with thermal decomposition. The yield of this method is often low, and it is not suitable for large-scale production.
When the content of active ingredients is relatively high and exists in the juice of plants, the juice can be extracted directly from fresh raw materials. Volatile oils can also be extracted from plant tissues by mechanical pressing, such as orange peel oil and lemon oil. It is performed at room temperature, so its components will not be decomposed by heat. However, the products obtained are impure and often contain impurities such as water, mucoid substances, and cell tissues, so they are often turbid, and it is not easy to press the volatile oil in plants entirely. Therefore, the crushed residue is often distilled by steam to extract volatile oils completely. For example, the black soybean oil from black soybean is often extracted with the low-temperature pressing method.
The separation of phytochemicals is a process of isolating the constituents of plant extracts or effective parts one by one and purifying them into monomer compounds by physical and chemical methods. Classical isolation methods, including solvent extraction, precipitation, crystallization, fractional distillation, salting-out, and dialysis, are still used commonly at present. On the other hand, modern separation technologies such as column chromatography, high performance liquid chromatography, ultrafiltration, and high performance liquid drop countercurrent chromatography also play an important role in the separation of phytochemicals. This section describes the common methods and their specific applications in isolation of phytochemicals.
It is carried out according to the different acidity and alkalinity of each component in the mixture. Water-insoluble alkaline organic components, such as alkaloids, could react with inorganic acids and form salts, which can be separated from nonalkaline and water-insoluble components. Acid components with carboxyl or phenolic hydroxyl groups can be salted by bases and dissolved in water. Components with lactone or lactam substructures can be saponified and dissolved in water and then isolated from other water-insoluble components. The total extract can be dissolved in lipophilic organic solvents (ethyl acetate is commonly used) and extracted respectively with acid water and alkali water, and then the total extract would be divided into acidic, alkaline, and neutral parts. Of course, the total extract can also be dissolved in water and extracted with organic solvents after adjusting the pH value. The alkalinity or acidity of the fractions are different and can be separated further by pH gradient extraction.
When using the acid and basic solvent method, attention should be paid to the strength of acidity or alkalinity, the contact time with the separated components, heating temperature, and time, so as to avoid the structural changes of some compounds under severe conditions or the chemical structures cannot be restored to the original states.
This method is to achieve the separation aim based on the different polarity of each component in plant extracts and the different partition coefficients in two-phase solvents. Generally, different two-phase solvent systems are selected according to the polarity of components in plant extracts. For example, the components with strong polarity can be separated by n-butanol-water system, the components with medium polarity can be separated by ethyl acetate-water system, and the components with weak polarity can be separated by chloroform (or ether)-water system. During the operation, the plant extract should be dissolved by water firstly, and then the solution or suspension is extracted in a separating funnel with different organic solvent which is not miscible with water based on the polarity difference. Usually, the extract was extracted with petroleum ether (or cyclohexane) firstly, then ethyl acetate (or chloroform), and finally with water saturated n-butanol, as shown in Figure 1. Petroleum ether layer contains lipid-soluble compounds with low polarity. Ethyl acetate layer contains medium polar compounds such as monoglycosides, flavonoids, and compounds with more polar functional groups. N-butanol layer contains compounds with strong polarity, such as oligoglycosides and other water-soluble components. Compounds in water layer possess strongest polarity, such as glycosides with more glycosyl groups, carbohydrates, amino acids, proteins, and other water-soluble compounds.
Flow charts of common polarity gradient extraction method.
It is a method based on the formation of precipitation of some phytochemicals by reaction with specific reagents, or the precipitation of some components from the solution by adding specific reagents, which can reduce the solubility of some components in the solution. The precipitation reaction must be reversible if the target components are required to form precipitation. While if the components are nontarget, the precipitation generated will be removed, so the precipitation reaction can be irreversible. According the addition of reagents or solvents, this method could be classified as follows [11].
The solubility of some components in the mixed component solution can be changed by adding a specific solvent that can be mutually soluble with the solution, so it can be precipitated from the solution. The gradual precipitation by changing the polarity or amount of solvent added is called fractional precipitation. For example, using water as an extracting solvent to extract phytochemicals, ethanol is added to the water extracting concentrate to make its alcohol content more than 80%, and then polysaccharides, proteins, starch, gum, and so on will be precipitated and removed after filtration. The preceding procedure is called water extraction and ethanol precipitation. Crude polysaccharides from plants are often separated with this method. For example, see [12].
Some reagents could react selectively with certain chemical constituents to produce reversible precipitation, and the separation aims are achieved, which is called the exclusive reagent precipitation method. For example, alkaloid precipitation reagents such as Reynolds ammonium salt can precipitate after reacting with alkaloids, which can be used to separate alkaloids and nonalkaloids, or water-soluble alkaloids and other alkaloids. As another example, reactions of cholesterol and sterol saponins could form precipitation, which can separate them from triterpene saponins. Additionally, gelatin can precipitate tannins, which can be used to separate or remove tannins. In practical application, appropriate precipitation reagents should be selected according to the properties of target constituents and impurities in plants.
Adding inorganic salts to a certain concentration or saturated state in the water extract of plants can reduce the solubility of some components in water, thus they could be separated from water-soluble compounds. The inorganic salts commonly used for salting out are sodium chloride, sodium sulfate, magnesium sulfate, ferric sulfate, etc. For example, extractions of tetrandrine from Daemonorops margaritae and berberine from Berberis poiretii could be achieved by salting out with sodium chloride or ammonium sulfate. Some water-soluble substances, such as proto-anemone, ephedrine, and matrine, are often extracted with organic solvents after adding a certain amount of salt to the water extract. For example, see [13].
It is a method to let substances selectively penetrate through natural or synthetic semi-permeable membranes (or dialysis bags) under the action of concentration difference, pressure difference, or potential difference, so as to achieve the purpose of separation, classification, purification, or concentration. For example, when saponins, proteins, polypeptides, polysaccharides, and other substances in plants are separated and purified, dialysis can be used to remove inorganic salts, monosaccharides, and other impurities. On the contrary, large molecular impurities can also be left in the semi-permeable membrane, while small molecular substances can be separated and purified through the semi-permeable membrane into the solution outside the membrane [14].
Fractional distillation is a method of separating components in liquid mixtures based on their different boiling points. It is usually categorized into atmospheric, vacuum, molecular distillation, and so on. It is mainly used for the separation of volatile oils and some liquid alkaloids in plants. For example, the boiling points of the two alkaloids in total alkaloids of Cicuta virosa, coniine, and conhydrine are 166–167°C for the former and 226°C for the latter, which are quite different from each other, and then they can be separated by the fractional distillation method. Generally, if the boiling point difference of compounds in liquid mixtures is above 100°C, the separation can be achieved by repeated distillation of the solution. If the boiling point difference of compounds is below 25°C, the fractionation column is needed. The smaller the boiling point difference is, the finer the fractionation device is needed [15].
Crystallization is the process of solute precipitation from mother liquor with complex components, and it is an effective method to prepare pure substances. The initial crystallization is often impure and needs to crystallize again, which is called recrystallization. It is a method to separate compounds from the mixture by using the difference of solubility of each component in the solvent. Crystallization is one of the important technologies for plant chemists to prepare pure compounds.
When the content of a phytochemical is very high in one plant, crystals can be obtained by cooling or slightly concentrating the extract after extraction with appropriate solvent. For example, see [16].
Selecting suitable crystallization solvent is the key of the crystallization method. The ideal solvents for crystallization should possess the following characteristics: high solubility for the components to be purified at high temperature, low solubility at low temperature, insoluble for the impurities at high and low temperature, or soluble for the impurities at high and low temperature, moderate boiling point, no chemical reaction with the components to be crystallized, safe, low price, easy to obtain, and so on. Solvents commonly used for crystallization are methanol, ethanol, acetone, ethyl acetate, acetic acid, pyridine, etc. When crystals cannot be obtained with a single solvent, the crystallization operation can be carried out with a mixture of two or more solvents. Mixed solvents generally consist of two miscible solvents, one of which has high solubility for the component to be crystallized, and the other has low solubility. Firstly, the sample to be crystallized is heated and dissolved in as few solvents as possible with high solubility. Then the second solvent with low solubility is added to the hot solution to make it turbid. Then the first solvent is added to dissolve the sample. The solution reaches saturation at this point and crystallizes when it is cooled. The purity of crystallization can be preliminarily identified by the crystal form, color, melting point, melting range, thin layer chromatography, paper chromatography, etc.
Chromatography is the most commonly used method for the separation of chemical constituents of natural products. It possesses advantages of high separation efficiency, rapidity, and simplicity. By choosing different separation principles, different operation modes, different chromatographic packings, or applying various chromatographic methods jointly, the separation and purification of various types of phytochemicals could be achieved. It can also be used for the identification of compounds.
It is a kind of chromatography based on the difference of adsorptive capacity of adsorbents to different compounds. The commonly used adsorbents include silica gel, alumina, activated carbon, polyamide, and so on. Silica gel adsorption chromatography is widely used, and it is suitable to the separation of most of the plant chemical constituents. Alumina adsorption chromatography is mainly used for the separation of alkaline or neutral lipophilic components, such as alkaloids, steroids, and terpenoids. Activated carbon is mainly used for the separation of water-soluble substances, such as amino acids, carbohydrates and some kinds of glycosides. Polyamide, which allows the separation to take place based on the formation of kinds of hydrogen bonds, is mainly used for the separation of phenols, quinones, flavonoids, anthraquinones, tannins, etc. [17].
Molecular sieve is the main principle of gel chromatography, which can separate mixture compounds according to the pore size of the gel and the molecular size of the compounds. Gel is a kind of solid material with a porous network structure. The molecules of the separated substances are different in size, so their ability to enter the gel is different. When the mixture solution passes through the gel column, the molecules smaller than the gel pores can enter the gel interior freely, while the molecules with larger size than the gel pores cannot enter the gel, and only pass through the gel particle gaps. Therefore, different movement rates are emerged. The molecules with large sizes are not excluded, and the retention time is shorter. The molecules with small sizes are detained because of its diffusion into the pores, thus the retention time is longer. There are many kinds of commercial gels, dextran gel and hydroxypropyl dextran gel are used most commonly [18].
It is to separate chemical constituents according to the difference of dissociation degrees. In this method, ion exchange resin is applied as stationary phase and water or solvent mixed with water as mobile phase. The ionic components existing in the mobile phase are absorbed by ion exchange resin after ion exchange reaction. Ion exchange chromatography is suitable for the separation of ionic compounds, such as alkaloids, amino acids, organic acids, peptides, and flavonoids. The ability of ion exchange reaction between compounds and ion exchange resins mainly depends on the compounds’ dissociation degree and the amount of electric charges. If the dissociation degree of a compound is high (acidic or alkaline), it is easily exchanged on resins and difficult to elute. Therefore, when the compounds with different degree of dissociation are exchanged on the resin, the compounds with lower degree of dissociation are eluted before those with higher degree of dissociation [19].
It is a chromatographic method which combines the principle of adsorption and molecular sieve. Its chromatographic behavior possesses reversed-phase properties. Macroporous resin is a kind of solid macromolecule material with no dissociable group and porous structure and is insoluble in water. It is widely used in the separation and enrichment of natural compounds because of its stable physical and chemical properties (insoluble in acids, bases, and organic solvents).
In practical work, the water solution of the mixture to be separated is usually washed by water, water-containing alcohol solution with low to high concentration. The mixture can be separated into several components. The regeneration of macroporous adsorbent resin is convenient. It is often washed by 1 mol/L hydrochloric acid and 1 mol/L sodium hydroxide solution, respectively, first, then washed by distilled water to neutral, and stored in methanol or ethanol. The alcohol should be washed out with distilled water before using.
It is a kind of chromatography method to separate components by using different partition coefficients between stationary phase and mobile phase, which are immiscible liquids. Partition chromatography could be divided into normal phase chromatography and reverse phase chromatography. The polarity of stationary phase is stronger than that of mobile phase in normal phase partition chromatography, which is mainly used to separate polar and moderately polar molecular compounds. Carriers commonly used in normal phase distribution chromatography include silica gel, diatomite, cellulose powder, etc. Silica gel with water content of more than 17% can be used as a carrier for partition chromatography because of its loss of adsorption. It is the most widely used carrier for partition chromatography. In reverse phase partition chromatography, the polarity of mobile phase is stronger than that of stationary phase. The commonly used stationary phase is octadecyl-silylated silica (ODS). The mobile phase is usually methanol-water or acetonitrile-water system, which is mainly used for the separation of nonpolar and moderately polar molecular compounds.
High performance liquid chromatography (HPLC) is a rapid separation and analysis technology developed on the basis of conventional column chromatography. Its separation principle is the same as regular column chromatography, including adsorption chromatography, gel chromatography, partition chromatography, ion exchange chromatography, and other methods. HPLC columns are produced with particle fillers (particle diameter 5–20 μm) and high pressure homogenate column loading technology. The eluents are pressed into the column by a high pressure infusion pump and equipped with high sensitive detectors and automatic recording and collection devices. As a result, it is far superior to conventional column chromatography in separation speed and efficiency. It has the characteristics of high efficiency, high speed, and automation. Preparative HPLC can be used to prepare a large amount of samples of high purity. HPLC has played an increasingly important role in the separation, qualitative identification, and quantitative analysis of plant chemical constituents. During the separation of many plant chemical constituents, it is necessary to separate trace constituents from a large amount of crude extracts. Usually, in the final stage of separation, samples with high purity are prepared by high or medium pressure liquid chromatography. Constant concentration eluents are mostly used in preparative HPLC. However, gradient elution is sometimes applied for samples that are difficult to be separated. Moreover, HPLC retains the advantages of liquid chromatography, such as a wide range of application and flexibility of mobile phase change. It can be applied to chemical constituents of difficult gasification, high molecular weight, or thermal instability.
The detectors commonly used in HPLC are ultraviolet detectors and differential refractive index detectors, but both have limitations. Differential refractive index detectors are sensitive to temperature change, the detection of a small amount of substances is often not ideal, and gradient elution cannot be used. As for ultraviolet detectors, they cannot detect samples without ultraviolet absorption. In recent years, a kind of mass detector, called evaporative light scattering detector (ELSD), has been applied in HPLC. It can not only detect samples without ultraviolet absorption, but also use gradient elution. It is suitable for most nonvolatile components [20].
DCCC is an improved liquid-liquid partition chromatography based on the counter-current partition method. The formation of droplets is required when the mobile phase passes through a liquid stationary phase column. Droplets of mobile phase contact with stationary phase effectively, and form new surfaces in thin partition extraction tubes constantly, which promote the partition of solutes in two-phase solvents, and the chemical components of mixtures are isolated in immiscible two-phase droplets due to different partition coefficients. This method is suitable for the separation of phytochemicals with strong polarity. The separation effect is usually better than counter-current partition chromatography, and there is no emulsification phenomenon. Furthermore, nitrogen is used to drive the mobile phase, so the separated substance will not be oxidized by oxygen in the atmosphere. However, the solvent system which can generate droplets must be selected in this method, the amount of sample treated is small, and special equipment is needed.
DCCC possesses good reproducibility, and can handle crude extract samples of milligram to gram grade. It can be used in either acidic or basic conditions. Because no solid separation carriers are used, the phenomenon of irreversible adsorption and band broadening of chromatographic peaks can be avoided. Compared with preparative HPLC, DCCC consumes less solvent, but the separation time is longer and the resolution is lower. For example, see [21].
HSCCC is also a liquid-liquid partition chromatography. It is another mild form of chromatography with no solid support and hence no chance of loss of substrate by binding to the column. The only media encountered by the sample are solvent and Teflon tubing. The former is common to all forms of chromatography and the latter to most. The chemical constituents with higher partition coefficient in mobile phase are eluted first, whereas those with higher partition coefficient in stationary phase are eluted later.
HSCCC chromatography could avoid the shortcomings of irreversible adsorption and abnormal tailing of chromatographic peaks caused by solid carriers in liquid chromatography because it does not need solid carriers. The sample recovery is near 100% from a chromatography. It also has advantages of good reproducibility, high purity of separated compounds, and fast speed. It is suitable for the isolation and purification of wide kinds of phytochemicals, such as saponins, alkaloids, flavonoids, anthraquinoids, lignans, triterpenes, proteins, and carbohydrates. For example, see [22].
It is an instrumental analysis method developed in the late 1980s combining classical electrophoresis with modern microcolumn separation technologies. In pharmaceutical analysis, the most commonly used separation modes are capillary zone electrophoresis, micellar electrokinetic capillary chromatography, and capillary gel electrophoresis. It is an efficient separation technology of large and small molecules in a hollow and thin inner diameter capillary (10–200 μm). The two ends of the capillary are immersed in a buffer solution and electrodes connected with a high voltage power supply are inserted separately. The voltage makes samples migrate along the capillary. According to the charge and volume of the separated substances, various molecules are separated under high voltage. In zone capillary electrophoresis, separation could be achieved by the movement of electrophoresis and electroosmotic flow. The strength of electroosmotic flow depends on the strength of electric field, PH value of electrolyte, composition of buffer solution, ionic strength, internal friction, and so on. Sample injection could be accomplished by pressing the sample into a capillary tube by atmospheric pressure or voltage.
HPCE has the advantages of high efficiency, microamount, economy, high automation, and wide application. However, it has the disadvantages of poor preparation ability, low sensitivity, and poor separation reproducibility. For example, see [23].
Affinity chromatography is a unique chromatographic separation method based on the principle of reversible combination of high affinity and specificity between molecules. By simulating the reversible and specific interaction between biological molecules, affinity chromatography uses the adsorption medium coupled with affinity ligands as the stationary phase to adsorb target compounds. It is a development of adsorption chromatography. This method can selectively separate and analyze specific chemical constituents from complex samples. Firstly, ligands that can specifically bind to the target compounds are fixed on the filler carrier to make the chromatographic column. Then the mixture containing the target compounds is passed through the column. Only the target compounds which show affinity with the ligands can bind to the ligands and remain in the column. Finally, the adsorbed target compounds are eluted by changing the composition of the mobile phase and are separated from other chemical constituents. AC is mainly used for the separation and purification of proteins, especially enzymes, antigens, and antibodies. Its application range has been expanding along with the continuous development of technology in recent years. For example, see [24].
The chemical structures of plant compounds must be identified or elucidated, which may provide the necessary basis for further study on the bioactivities, structure-activity relationships, metabolisms in vivo, structural modification, and synthesis of the active phytochemicals.
The quality of physiological active substances isolated from plants is often small, sometimes only a few milligrams, and the structural studies are often difficult to carry out with classical chemical methods, such as chemical degradation, derivative synthesis, etc. Therefore, spectral analysis is mainly used, that is, consuming sample as little as possible to obtain structural information as much as possible by measuring various spectra. Then comprehensive analysis is carried out with the assistance of literature data. If necessary, chemical means would be integrated into the former methods to determine the planar- and even the stereo-structures of the compounds.
Before the structural investigation of an active compound, the purity must be determined, which is a prerequisite for the structural identification.
The crystals of each compound have certain shape, color, and melting point, which can be used as the basis for the preliminary determination of the purity. Generally, the crystal shape of a specific compound under the same solvent is consistent, the color is pure, and has a short melting range (generally at 1~2°C). But for compounds with double melting points or amorphous substances, the purity cannot be determined by this method.
TLC, such as silica gel and paper chromatography, is the most commonly used method to determine the purity of compounds. Generally, a specific sample, showing an only spot (Rf value at 0.2~0.8) in three different developing agents, could be considered as a pure compound. In some cases, both normal and reverse phase chromatographic methods are needed.
GC and HPLC are important methods in the purity determination of phytochemicals. GC is widely used in the analysis of volatile compounds. Both volatile and nonvolatile substances could be analyzed with HPLC, which possesses various advantages of high speed, high efficiency, sensitivity, and accuracy.
The general procedures of structural determination of phytochemicals are shown roughly in Figure 2.
The main procedures for studying the structures of phytochemicals.
The structural identification of phytochemicals can be greatly simplified according to the researchers’ habits, experiences, and skill levels of different technologies. However, the literature search almost runs through the whole process of structural research, no matter for known or new compounds. A large number of facts have been proved that taxonomically related plants, that is to say, plants of same or similar genus often contain chemical constituents of similar or even same chemical structures. Therefore, it is necessary to investigate literatures of chemical studies of the study object and the plants of its same and similar genera. It is necessary to understand not only the components from different plants of similar genera, but also their extraction methods, physicochemical properties, spectral data, and biosynthesis pathways before the extraction and separation of one specific plant. The SciFinder Scholar database is used most widely to quickly determine whether the compound was “known” or “unknown”.
At present, spectrum analyses have become the main means to determine the chemical structures of plant chemicals. Particularly, with the developing of the superconducting nuclear magnetic resonance (NMR) and mass spectroscopic (MS) technologies, the speed of structural determination is greatly accelerated and the accuracy is improved. Here, the applications of infrared (IR), ultraviolet (UV), nuclear magnetic resonance (NMR), and mass (MS) spectra in the structural identification of phytochemicals are introduced briefly.
UV-vis spectrum is a kind of electron transition spectrum, which is generated after the molecules absorbing the electromagnetic waves with wavelength at the range of 200–800 nm. The valence electrons in the molecules absorb light of certain wavelengths and jump to the excited state from the ground state, and then UV spectra are recorded.
Compounds containing conjugated double bonds, α,β-unsaturated carbonyl groups (aldehydes, ketones, acids, and esters), and aromatic compounds could show strong absorption in UV spectra because of n → π* or π → π* transitions. Therefore, UV spectrum is mainly used to identify the presence of conjugated systems in the structures.
UV spectra could provide the following information: (1) the compounds show no UV absorption at 220–800 nm, indicating the compounds were aliphatic hydrocarbons, aliphatic cyclic hydrocarbons, or their simple derivatives. (2) The compounds show strong absorption at 220–250 nm, indicating that the compounds possess conjugated diene, α,β-unsaturated aldehyde, or ketone substructures. (3) The absorption at 250–290 nm is moderately strong, indicating that the compounds possess benzene rings or aromatic heterocycles. (4) Weak absorption at 250–350 nm indicates the presence of carbonyl or conjugated carbonyl groups. (5) Strong absorptions at above 300 nm indicate that the structures possess long conjugated chains.
Generally, UV spectrum can only provide part of the structural information, rather than the whole structural information of a compound, so it can only be used as an auxiliary method to identify the structures. It possesses practical value to determine the structures of phytochemicals with conjugated substructures.
IR is caused by the vibration-rotational energy level transition of the molecule, ranging from 4000 to 625 cm−1. The region above 1250 cm−1 is functional group region, and the absorption of characteristic functional groups such as hydroxyl, amino, carbonyl, and aromatic rings occurs in this region. The region of 1250 to 625 cm−1 is fingerprint region, and the peaks appear mainly due to the stretching vibrations of C-X (X = C, O, N) single bonds, and various bending vibrations. IR is mainly used for the determination of functional groups and the types of aromatic ring substitution. In some cases, IR can also be used to determine the configuration of plant chemical constituents. For example, there is a significant difference between 960 and 900 cm−1 for 25R and 25S spirostanol saponins.
In a mass spectrometer, mass and strength information of molecular and fragment ions is recorded after the molecules are ionized and enter into the collector under the action of electric and magnetic fields. The abscissa represents the mass-to-charge ratio (m/z) and the ordinate represents the relative intensity in a MS spectrum. Unlike IR, UV, and NMR spectra, MS is mass spectrum, which characterizes fragment ions, not an absorption spectrum. Its role is to determine weights, formulas, and fragment structures of molecules.
With the rapid development of modern techniques, new ion sources have emerged in recent years, which make MS play more important role in determining the molecular weights, elemental composition, detecting functional groups by cleavage fragments, identifying compound types, and determining carbon skeletons [25]. In the structural analysis, the information of molecular weights could be obtained on the basis of molecular ion peaks, and the molecular formula could be obtained by high-resolution mass spectrometry (HR-MS). Fragment ion peaks, combined with molecular ion peak, could be applied to conjecture chemical structures. Tandem mass spectrometry even can isolate and analyze the mixed ions again. According to the types of ion sources, common mass spectrometry could classified as electron impact mass spectrometry (EI-MS), chemical ionization mass spectrometry (CI-MS), field desorption mass spectrometry (FD-MS), fast atom bombardment mass spectrometry (FAB-MS), matrix-assisted laser desorption mass spectrometry (MALDI-MS), electrospray ionization mass spectrometry (ESI-MS), tandem mass spectrometry (MS–MS), and so on.
With the birth of Fourier transform spectrometer, the great progress of radionuclide research such as 1H, 13C, 15N, 19F, 31P, and the advancement of two-dimensional and three-dimensional nuclear magnetic technology, NMR has become the most important spectroscopic method to determine chemical structures. Particularly, hydrogen spectrum and carbon spectrum are most widely used. During the operation of nuclear magnetic resonance spectrometer, compound molecules are irradiated by electromagnetic waves in a magnetic field, energy level transitions occur after the atomic nuclei with magnetic distance absorb a certain amount of energy, and then NMR spectrum is obtained by mapping the absorption strength with the frequencies of the absorption peaks. It can provide structural information about the type and number of hydrogen and carbon atoms in the molecule, the modes they are connected, the surrounding chemical environment, configuration, and conformation [26].
Samples used to measure NMR spectra include solids, liquids, and gases. Liquid high-resolution NMR is most widely used. The solvent used in the measurement of NMR must be deuterated. The commonly used deuterated reagents to dissolve samples and their chemical shifts of their residual proton and carbon signals are shown in Table 1.
Solvent | δC | δH |
---|---|---|
CDCl3 | 77.0 | 7.24 |
CD2Cl2 | 53.8 | 5.32 |
CD3OD | 49.0 | 3.3 |
Acetone-d6 | 29.8, 206.0 | 2.04 |
D2O | — | 4.7 |
DMSO-d6 | 39.5 | 2.49 |
C6D6 | 128.0 | 7.16 |
C5D5N | 123.6135.6149.9 | 7.2, 7.6, 8.7 |
Chemical shifts of common deuterated solvents (TMS is an internal standard).
Resonance absorption peaks are generated after hydrogen protons absorb electromagnetic waves of different frequencies in an external magnetic field. 1H-NMR possesses high sensitivity, easy measurement, and wide application. 1H-NMR spectrum can provide structural information of chemical shifts (δ), coupling constants (J) that indicate the coupling relationships between different hydrogen nucleus, and the number of protons (the peak area is proportional to the number of protons that cause the absorption).
Because of the different surrounding chemical environment, the 1H nuclei possess different magnetic cloud densities and magnetic shielding effects caused by the rotation around the nucleus, and then different types of 1H nuclear resonance signals appear in different regions. Tetramethylsilane (TMS) is usually used as a reference compound. Compared with the general compounds, the shielding effect of protons and carbons on the methyl groups is stronger in TMS. Therefore, regardless of the hydrogen spectrum or the carbon spectrum, the absorption peaks generated by the general compounds appear in the lower field than TMS, that is to say, δ values generated by common compounds is positive. The chemical shifts of the 1H-NMR spectrum is mostly in the range of δ0–20. Some typical chemical shifts of 1H nuclei are shown in Figure 3 [4].
1H-NMR chemical shift range of common hydrogen protons.
In addition to the normal 1H-NMR spectrum technique, there are some auxiliary techniques that assist in structural analysis, such as selective decoupling, heavy hydrogen exchange, addition of reaction reagents, and dual irradiations.
13C-NMR spectra can provide structural information of organic compounds, including the number, types, and chemical environment of carbon atoms [27]. It is one of the important means for the structural identification of organic compounds. Especially, where there are serious signal peak overlaps in the 1H-NMR spectrum, or the molecules contain several quaternary carbon atoms, 13C-NMR spectra will provide crucial information for the structure identification. The chemical shifts of common carbon signals are shown in Figure 4 [4].
13C-NMR chemical shifts of common carbon signals.
Common 13C-NMR techniques include proton broadband decoupling, off resonance decoupling (OFR), insensitive nuclei enhanced by polarization transfer (INEPT), and distortionless enhancement by polarization transfer (DEPT). Proton broadband decoupling and DEPT spectra are most commonly used at present.
Proton broadband decoupling spectrum is measured after 1H nuclei are saturated with broadband electromagnetic radiation. At this point, the couplings between 1H and 13C are completely eliminated, and all 13C signals are shown as singlets, so it is very convenient to determine the chemical shift of 13C signals. In addition, because of the NOE effect of 1H after irradiation, the signal of 13C signal connected with 1H will be increased, while the quarterly carbon signal will show weak absorption peaks.
It is an improved method of INEPT, in which a J-modulation is accompanied by a polarization transfer from the protons to coupled carbons, leading to significant improvement in sensitivity. In DEPT spectrum, by changing the pulse width (θ), which could be designed as 45o, 90o, and 135o, during irradiation of 1H, different carbons could show different strengths and signs. The results are similar with INEPT spectrum. When θ = 45o, all CH, CH2, and CH3 groups display positive signals; when θ = 45o, only CH groups show positive signals; when θ = 135o, both CH and CH3 groups show positive signals, while CH2 groups show negative signals. Quarterly carbons show no signal peaks in DEPT spectra. An example of DEPT spectra is shown in Figure 5.
The DEPT spectrum of Arctiin (CD3OD).
Two-dimensional correlation spectroscopy (2D-COSY) is the most important and widely used in 2D-NMR spectroscopy. 2D-COSY spectra can be divided into homonuclear and heteronuclear correlation spectra. Both abscissa and ordinate represent chemical shifts in 2D-COSY. Common correlation spectrum types are show as follows.
It is a kind of chemical shift correlation spectrum between 1H and 1H. It is the coupling correlation spectrum between protons in the same coupling system. The adjacent hydrogen groups could be determined by their coupling relationships (3J) shown in 1H-1H COSY spectra.
In addition, for compounds of aromatic systems, double bond systems, and some particular configuration systems, 1H-1H COSY spectra can show 4J coupling or longer coupling relationships of hydrogen groups. It is very important for the elucidation of an unknown structure.
1H detected heteronuclear single quantum coherence (HSQC) and 1H detected heteronuclear multiple quantum coherence (HMQC) can display the correlations between 1H and 13C. HSQC possesses higher sensitivity and wider application than HMQC. In the HMQC or HSQC spectrum, the signals occurred at the crosses of chemical shifts generated by corresponding carbons and protons (Figure 6).
Schematic diagram of correlations between 1H and 13C in the HSQC or HMQC spectrum.
HMBC spectrum is short for 1H detected heteronuclear multiple bond correlation, which associates the 1H nucleus with 13C nucleus of long-range coupling. HMBC could detect the long-range coupling of 1H-13C sensitively (nJCH, n≧2). Moreover, the correlation signal peaks between protons and quaternary carbons that are two or three bonds apart could also be shown in HMBC spectra, as shown in Figure 7. From the HBMC spectrum, we can get the connection information of the carbon chain skeletons, the structure information of the quaternary carbons, and the structural information of the coupling systems that are cut off by heteroatoms.
Schematic diagram of correlations between 1H and 13C in the HMBC spectrum.
When two groups of protons are located at rather close spatial distances, irradiation of one group will enhance the signal strength of another, which is known as nuclear Overhauser enhancement (NOE). The NOE spectrum can determine the spatial relative position, stereoscopic configuration, and dominant conformation of some groups in the molecule, which is very important for the study of the stereostructures of organic compounds.
2D-NOE (NOESY) spectra could show the NOE correlations of protons. The greatest advantage of NOESY is that all the NOE information between protons of a compound could be shown in one spectrum. However, not all the cross peaks are NOE correlation signals, the residual correlation signals of COSY are often shown in NOESY spectrum as well, which should be paid attention during spectroscopic analysis.
The TOCSY spectrum shows the correlation of the entire spin system, which is different from the ordinary 1H-1H COSY. The relationships between the nuclei that generated the correlation peaks are shown in Figure 8. Not only the correlation signals of a proton with protons connected to the adjacent carbons, but also its correlation signals with other protons in a whole spin system could be shown in the TOCSY spectrum, which provides important basis for the connection of structural fragments.
Schematic diagram of correlations between 1H and 13C in the TOCSY spectrum.
HSQC-TOCSY is a kind of combined 2D-NMR spectrum. Comprehensive results of HSQC and HMBC are obtained by using a long pulse sequence. The correlation is shown in Figure 9. It is very useful for the assignment of carbon and proton signals in complex chemical structures. For example, for saponins with a series of glycosyl groups, the signals generated by glycosyl groups are often overlapped seriously in common NMR spectra, which causes difficulty to assign signals of glycosyls. HSQC-TOCSY spectrum will play an important role in this case. The spectrum includes the information of HSQC, HMBC, and 1H-1H COSY.
Schematic diagram of correlations between 1H and 13C in the HSQC-TOCSY spectrum.
Polarimetry is an optical method used widely in the studies of asymmetric structures, which appeared very early. The progress of the sensitive method such as ORD and CD made it possible to study stereostructures of chiral compounds more deeply. Both of them are spectra related to the optical activity of compounds, and could provide information of absolute configurations, dominant conformations, and reaction mechanisms of chiral compounds, that cannot be replaced by any other spectroscopic methods [28].
The specific rotation [α] of a chiral compound depends upon the wavelength of the monochromatic light wave. The measurement of specific rotation as a function of wavelength is called optical rotator dispersion (ORD). The common types of ORD curves are as follows.
The ORD spectrum of an optically active compound with no chromophores is plain without peaks and troughs. An ORD curve of specific rotation increases with decrease of wavelength which is called positive plain curve, while in the case of negative plain curve, negative rotation increases with decrease of wavelength (see Figure 10).
ORD plain curves (A: Positive plain curve; B: Negative plain curve).
If there is a simple chromophore in the molecule, the ORD curve is very different from plain curve. Near the absorption wavelength region of chromophore, a peak and a trough are exhibited, which is called the Cotton effect, and the spectrum drawn is called the Cotton effect curve. The spectrum with only one peak and one trough is called pure Cotton effect curve, while the spectrum with several peaks and troughs is called complex Cotton effect curve. The Cotton effect is called positive when the trough is observed at a shorter wavelength then peak. Conversely, the Cotton effect is called negative if the trough is observed at a longer wavelength than the peak. Cotton curves of △5-cholestenone are shown in Figure 11, which shows A and B possess the same structural formula, while different opposite configurations.
The Cotton effect curves of △5-cholestenone (A) natural cholesterone (+) cotton; (B) Cholesterone in the opposite absolute configuration (−) cotton.
For compound with two or more different chromophores, its ORD curve may possess multiple peaks and troughs, which is called complex Cotton effect curve. Each ORD curve is the average effect of each chromophore in the molecule, and the contribution of each orientation and conformation of the molecule. Hence the Cotton effect curve is often complex.
Optically active compounds have different molar absorption coefficients for left-circularly and right-circularly polarized light that make up plane polarized light, which is called circular dichroism (CD). The difference value between the two molar absorption coefficients (Δє = єL−єR) changes with the wavelength of the incident polarized light. With Δє as the ordinate, the wavelength as the abscissa, the spectrum obtained is called circular dichroism spectrum. Because the absolute value of Δє is very small, it is often replaced by molar ellipticity [θ]. The relationship between [θ] and Δє is as follows.
Because Δє could be positive or negative, the circular dichroism curve also could be classified as positive and negative. In the CD spectrum showing positive Cotton effect, only a peak appears near the λmax of the chromophore in the molecule. Conversely, a trough appears in the CD spectrum showing negative Cotton effect. Therefore, CD spectra are simpler and easier to analyze than ORD spectra. For example, the ORD and CD spectra of (+)-camphor are shown in Figure 12. CD is more widely used than ORD in the study of chiral compounds.
The ORD and CD spectrum of (+)-camphor.
Single crystal X-ray diffraction could be applied independently to analyze the structures, components, contents, configurations, conformations, solvents, and crystal forms of samples. It is widely used in the stereostructural study of natural compounds, synthetic compounds, peptides, proteins, etc. Therefore, X-ray diffraction analysis is a necessary physical method in the field of structure and function research of modern natural drugs.
Single crystal X-ray diffraction is a kind of quantitative analysis technology, which can provide three-dimensional structural information of molecules, including atomic coordinates, bond length, bond angles, dihedral angles, hydrogen bonds, salt bonds, coordinate bonds, and so on. In addition, it is also a reliable method to determine the absolute configuration of chiral drug molecules and the epimers in the stereochemical structures. For example, see [29].
In recent years, study on phytochemicals from plants becomes more and more popular due to their demonstrated health benefits. A number of plants having high contents of phytochemicals (particularly phenolic acids and flavonoids) with associated antioxidant activities have been increasingly utilized. Complementary research is also needed to enhance the potential functionalities of the phytochemicals in future, where such plants have shown to contain numerous phytochemicals that may be beneficial to human health. The compiled results indicated that many of their bioactive compounds remain to be fully isolated, identified, and characterized (alkaloids, diterpenoids, and so on).
Therefore, phytochemicals can be considered as the source of natural medicines. The compounds of plants are bioaccessible and bioavailable in humans with some demonstrated health benefits, including antioxidant, anti-inflammatory, anti-cancer, anti-microbial, hypoglycemic action, etc. Additional well-designed human intervention studies and clinical trials are needed to validate the health benefits of phytochemicals.
Enterococci are Gram-positive, non-spore forming and facultative anaerobic cocci. They are indigenous flora of the intestinal tract, oral cavity and vagina in healthy persons. The genus comprises 54 species which are ubiquitously present in nature [1]. Enterococci have emerged as an important nosocomial pathogens second to Staphylococci which is the leading cause of nosocomial infections worldwide [2]. Enterococci are important nosocomial pathogens causing up to 10% of all infections in the hospitalized patients [3]. In these Enterococci infections approximately 60% of infections are caused by Enterococcus faecalis and Enterococcus faecium causes the remaining [4]. In the last decade both E. faecalis and E. faecium have emerged as important nosocomial pathogens. Other Enterococcal species causing nosocomial human infections are E. avium, E. gallinarum, E. casseliflavus, E. durans, E. raffinosus and E. mundtii. Majority of clinical isolates (63–81%) are identified as E. faecalis, around 13–23% as E. faecium and other enterococcal species comprise around 3–4% of the clinical isolates [5].
\nNosocomial infections particularly by vancomycin resistant Enterococci (VRE) have become a major problem since last few years though VRE are organisms of low virulence and pathogenicity. Nosocomial infections caused by VRE are highly prevalent in intensive care units of hospitals. These infections are particularly high in presence of underlying health factors like diabetes, liver transplantation, neutropenia, diabetes mellitus and renal dysfunction. Recently it has also been seen that VRE bloodstream infections have higher mortality rates as compared to vancomycin susceptible Enterococci (VSE) [6, 7]. Data from countries like Germany shows an increase of VRE from less than 5% in 2001 to 14.5% in 2013 mainly vancomycin resistant E. faecium [8]. In Europe of all the nosocomial infections reported 9.6% were of Enterococci [9]. In USA 3% of the nosocomial infections are due to VRE [10]. VRE nosocomial infections cause greater number of invasive treatment resulting in extended stay in hospital and cost [11]. Hospitals in some countries have now established VRE screening in high risk areas and isolation of patients to prevent spread of the resistant pathogen [12]. A study has shown the prevalence of VRE colonization in patients who had history of previous administration of antibiotics for more than 2 weeks were 10 times more likely of getting VRE colonization [13]. Other studies have also reported similar findings which show antibiotic exposure can cause colonization of VRE in hospital settings because of their resistance to commonly used antibiotics, virulence factors and ability to acquire genes [14].
\nThe genes Van A, Van B, Van C, Van D and Van E are responsible for vancomycin resistance in Enterococci. Van M has been identified which is also an important vancomycin resistant determinant among different E. faecium lineages in hospitals in Shanghai, China [15]. Each Van operon has different ecological origin, Van A has originated from soil organisms, van B, Van G and Van D from gut microbiota [16]. Vancomycin resistance in Enterococci is of two types (a) Intrinsic resistance—Enterococci spp. like E. gallinarum and E. casseliflavus show an inherent low level resistance to Vancomycin. They have Van C genes that produce Vancomycin minimum inhibitory concentration (2–32 μg/ml) [17] A hospital wide outbreak of vancomycin resistant E. gallinarum has been reported in Colombia showing that uncommon species of Enterococci are capable of spreading in the hospital environment and producing nosocomial infections [18]. The second type is (b) acquired resistance—Enterococci species acquire resistance genes and become resistant to vancomycin. This is seen in E. faecium and E. faecalis and to some extent in E. raffinosus, E. avium, E. durance and other enterococcal species. The most common isolated Enterococci species which is VRE in hospital settings is E. faecium. It has been seen that E. faecium produces high vancomycin minimum inhibitory concentration (64–1000 μg/ml) [19]. There has been a significant increase in VRE prevalence. The emergence and rapid spread of VRE has led to the use of new antibiotics like linezolid, daptomycin and tigecycline. Linezolid is a oxazolidinone antibiotic. An oxazolidinone resistance gene optr A has been identified in E. faecalis and E. faecium isolates of human and animal origin [20] .Linezolid resistance is still less prevalent reported as 1.1 and 1.8% in E. faecium and E. faecalis isolates from 19 US hospitals [21]. Daptomycin resistance is more prevalent in E. faecium than E. faecalis isolates. Around 3.9 and 0.2% of E. faecium and E. faecalis isolates have been reported in various hospital settings [22]. Tigecycline is a semisynthetic derivative of tetracycline. Tigecycline resistance in E. faecium and E. faecalis is rare and reported as 0.3%. It is being used to treat bacteremia caused by MDR enterococci. The increased use of antibiotics in hospitals is causing gut dysbiosis and enterococci possess surviving ability take over the niche in the gastrointestinal tract and this could be the primary source of enterococcal infections [23].
\nThe ability of E. faecium to exchange mobile genetic elements carrying antimicrobial resistance genes and virulence determinants has resulted in hospital adapted clones [24]. Esp was the first adaptive element found in hospital strains of E. faecium. The E. faecium esp. gene has been linked to biofilm formation, UTI and endocarditis [24]. New determinants have been now linked to hospital isolates of E. faecium. A genomic analysis study of E. faecium hospital strains identified gain and loss of gene clusters in clinical and non-clinical isolates of E. faecium [25]. Genomic studies of nosocomial E. faecium infection have confirmed the transmission of E. faecium Clad A115. Recently it has been seen a significant presence of hospital associated VRE fm lineages in the wastewater and need of controlling healthcare associated dissemination of VRE fm [26]. However studies on E. faecalis ecotypes have shown no appearance of distinct E. faecalis strains over a significant period of time. Virulence factors like antibiotic resistance and virulence genes, esp., capsule polysaccharide genes and genes determining gelatinase, aggregation factor, cytolysin and ace are identified in E. faecalis isolates [27]. The non-emergence of distinct ecotypes of E. faecalis and multiplicity of closely related ecotypes is not seen in E. faecalis as compared to E. faecium. A genomic analysis of 168 E. faecalis hospital isolates showed no genes and non-synonymous single nucleotide polymorphisms in the three lineages of hospital strains [28]. A recent study has also demonstrated that the acquisition of mobile genetic elements in E. faecalis V583, makes it unable to coexist with commensal enterococci in humans [29].
\nNosocomial infections by Enterococci are Urinary tract infection, endocarditis, bacteremia, catheter related infections, wound infections, intra- abdominal and pelvic infections and recently even oral infections have been reported.
\nEnterococci cause both uncomplicated and complicated health care associated UTI. E. faecalis. Vancomycin resistant E. faecalis and vancomycin resistant E. faecium have been mainly implicated in Enterococcal UTI. VRE is fast becoming a major cause of health care associated UTI. The treatment of UTI involves the use of broad spectrum antibiotics which is a major cause of resistant strains to vancomycin (VRE). The complications range from uncomplicated cystitis, pyelonephritis, perinephric abscess, and prostatitis. These organisms are responsible for nosocomial infection of urinary tract particularly in intensive care units (ICU). Enterococci have been particularly reported in catheter associated urinary tract infections, CAUTI (28.4%). Enterococci species are capable of producing biofilms, which are a population of cells attached irreversibly on various biotic and abiotic surfaces. CAUTI are associated with multispecies biofilms. Biofilms are difficult to remove and result in many chronic infections. Bacteria in biofilms colonize medical devices such as catheters, pacemakers, prosthetic heart valves and orthopedic appliances [30]. These multispecies biofilms have synergistic or antagonistic effects of interspecies interaction. Many studies have shown the association of biofilm producing enterococci and urinary catheter [31, 32]. Enterococci biofilms which are formed on catheter in CAUTI are resistant to immune clearance, urination force and even antibiotics. These enterococci utilize fibrinogen formed on catheter surface and form resistant biofilms. E. faecalis attachment in biofilm formation seen in vitro is partially inhibited by uropathogenic E. coli (UPEC) but biofilm formation by K. pneumoniae or UPEC are not affected by E. faecalis but E. faecalis increased E. coli biofilm mass accumulation and it has been seen that co-culture of an E. faecium probiotic strain with enteropathogenic E. coli increased the antibiotic sensitivity of E. coli to aminoglycosides, B-lactams and quinolones [33]. Biofilm formation confers the organism resistance to phagocytosis and antimicrobial agents. UTI by E. faecalis is mediated by virulence factors of the genes esp., srtC, ebp A, ebpC, ace, epaB, msrA, msr B, sigV, efbA, and grvR/etaR. E. faecium also displays similar genes related to virulence. Both E. faecalis and E. faecium isolated from nosocomial UTIs show kidney tropism. It is important to study factors in enterococcal causing pyelonephritis [33].
\nThere is a high prevalence of blood stream infections caused by Gram-positive bacteria and 45% are caused by Enterococci. Bacteremia is a common manifestation of vancomycin resistant Enterococci. Due to use of intravascular and urinary catheters these nosocomial infections are acquired. E. faecium in the blood stream is associated with increased mortality due to high levels of resistance. Risk factors identified with VRE bacteremia include intestinal colonization, long term antibiotic use, severity of illness, bone marrow transplant, hematologic malignancy, indwelling urinary catheters, corticosteroid treatment, chemotherapy and parenteral nutrition [34]. Studies have shown that bacteremia caused by vancomycin resistant Enterococci strains carry higher mortality rates (2.5-fold increase) as compared to bacteremia caused by vancomycin sensitive strains. In one such study the prognosis of VRE bacteremia was not much changed even with the availability of antimicrobial agents with greater potency. E. faecalis sigma factor Sig V that regulates gene expression in response to stress conditions has been implicated in enterococci survival and colonization in systemic infection. Absence of sig V in systemic infection in mice resulted in attenuation of bacterial translocation reducing colonization of kidney and liver. Virulence factors like Bgs A and Bgs B have also been implicated in colonization of endocarditic lesions and bacteremia. BgsA and Bgs B are now being used to treat enterococcal infections by using them as drug targets [35]. Similarly gene Asr has been implicated in E. faecium pathogenesis in systemic infections. Nosocomial enterococcal bacteremia have been associated with urinary catheters, intra-abdominal, burn wound, pelvic, biliary and bone sources. VRE bacteremia results in 2.5-fold increase in mortality as compared to vancomycin sensitive (VSE) bacteremia [18].
\nEnterococci are the second most cause of infective endocarditis. Endocarditis caused by VRE faecalis causes GI or GU manipulation, damaged mitral or aortic valve infections, liver transplantation whereas VRE faecium endocarditis is associated with infection of tricuspid valve [36]. E. faecalis is also associated with community acquired endocarditis. Characteristic signs of infection include fever or a new murmur. Typical stigmata of endocarditis like petechiae, osler spots are rare and occur with sub-acute infections. Genitourinary infection or instrumentation often precedes the onset of enterococcal endocarditis. In published series of enterococcal endocarditis men often outnumber women and mostly it occurred in elderly individuals. In the current therapeutic regimes, the mortality rate of enterococcal endocarditis remains around 20%.
\nVRE has been isolated from intra-abdominal and pelvic infections. The usual infections include abscesses wounds or peritonitis. Often it is a part of polymicrobial infection with Gram negative or anaerobic organisms. Usually infecting strains originate from patients intestinal flora and cause intra-abdominal infection. Enterococci are able to cause monomicrobial peritonitis infections particularly in patients undergoing chronic peritoneal dialysis or liver cirrhosis.
\nGI related enterococcal infections are opportunistic infections particularly occurring during colorectal surgery and colorectal cancer. Pre-colonization with VRE in patients can result in bacteremia following antibiotic induced disruption of gut microbiota [37]. Reg IIIy, a c type lectin is secreted by intestinal epithelial and paneth cells that removes Gram positive bacteria from the gut. Antibiotic treatment causes Reg IIIy down-regulation [38]. Therapeutic strategies have been devised to prevent intestinal colonization of resistant enterococci, introducing probiotic E. faecalis pheromone induced killing of drug resistant E. faecalis reactivating Reg IIIy introducing obligate anaerobic commensal bacteria containing Barnesiella species which prevents E. faecium gut colonization and bacteremia [39]. High collagenase producing E. faecalis strains have been found to be associated with colorectal anastomotic leak by activating tissue matrix metalloproteinase 9 that cleaves host extracellular matrix [40]. Enterococci produce menaquinone and extracellular superoxide in intestine. This results in high oxidative stress which is linked with colorectal cancer as high genomic instability of intestinal tumor cells as around 80% of colon cancers are caused due to genetic mutations.
\nAlthough CNS infections have been reported rarely with VRE but occur in elderly patients having underlying health issues like malignancies, pulmonary and cardiac complications [41]. In them VRE faecium is reported at 82% and less so of VRE faecalis. These infections present as fever, mental disorientation, focal CNS deficits and petechial rash. CSF investigations show pleocytosis, low glucose and increased protein levels.
\nEnterococci are part of polymicrobial infections which are found to be associated with SSSE [42]. Enterococci are frequently isolated from diabetic foot ulcers and 2–5% of patients undergoing inpatient surgery. In studies using animal models it has been seen that E. faecalis capsular polysaccharide in SSSI predominantly is related to the persistence of the organism. A gene cpsI encodes the carbohydrate for capsular polysaccharide.
\nEnterococci are inhabitants of the oral cavity and as opportunistic pathogen cause oral diseases like caries, endodontic infections, periodontitis and peri-implantitis. In endodontic infections the failure of root canal treatment by endodontic infections is now well evidenced. Enterococci have high resistance to endodontic medicaments and forms resistant biofilms. This is implicated in root canal treatment failure [43, 44]. Enterococci prevalence is also seen in gingivitis and periodontitis (3.7–35%) [45]. Oral Enterococci constitute the highest percentage of virulent genes and ability to form resistant biofilms. The oral cavity may hence be an important reservoir of virulent antibiotic resistant enterococci strains. VRE colonization occurs mainly in GI tract, skin, genitourinary tract and oral cavity. Enterococci can persist from months to years. The hands of health care workers are the most common source of transmission in nosocomial infections [46]. The need of oral care is particularly important in nosocomial settings. The spread of the nosocomial VRE occurs and when the immunity is lowered VRE multiply to cause disease. Few studies have shown that antibiotic resistant enterococci is transmitted by food [47, 48, 49] but recently Vidana et al. [50] have said there is no food related transmission of enterococci. Enterococci are now showing a high degree of resistance to tetracycline, chloramphenicol, erythromycin besides vancomycin pose a threat for spread of nosocomial infection particularly in patients of ICUs and on mechanical ventilators [51]. Vancomycin resistance is an independent predictor for the overall increase of hospital costs for the patient but also for the individual hospital [52].
\nVRE and have now become an important nosocomial pathogen globally. VRE causes range of infections from UTI, bacteremia, infective endocarditis, intra-abdominal and pelvic infections, central nervous system infections and even oral infections. The ability of enterococci to form recalcitrant biofilms, colonize and express virulence factors, genome plasticity, resistant to antibiotics, survival ability makes it an important nosocomial pathogen to which new therapeutic strategies have to be devised for the treatment of VRE. A periodic surveillance of VRE in hospitals is essential for limiting the spread of antibiotic resistance. Future therapy should be targeted to prevent VRE colonization of patients with immunosuppression.
\nContent alerts
",metaTitle:"Content alerts",metaDescription:"Content alerts",metaKeywords:null,canonicalURL:"/page/content-alerts",contentRaw:'[{"type":"htmlEditorComponent","content":"Content alerts
\\n"}]'},components:[{type:"htmlEditorComponent",content:"Content alerts
\n"}]},successStories:{items:[]},authorsAndEditors:{filterParams:{sort:"featured,name"},profiles:[{id:"6700",title:"Dr.",name:"Abbass A.",middleName:null,surname:"Hashim",slug:"abbass-a.-hashim",fullName:"Abbass A. Hashim",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/6700/images/1864_n.jpg",biography:"Currently I am carrying out research in several areas of interest, mainly covering work on chemical and bio-sensors, semiconductor thin film device fabrication and characterisation.\nAt the moment I have very strong interest in radiation environmental pollution and bacteriology treatment. The teams of researchers are working very hard to bring novel results in this field. I am also a member of the team in charge for the supervision of Ph.D. students in the fields of development of silicon based planar waveguide sensor devices, study of inelastic electron tunnelling in planar tunnelling nanostructures for sensing applications and development of organotellurium(IV) compounds for semiconductor applications. I am a specialist in data analysis techniques and nanosurface structure. I have served as the editor for many books, been a member of the editorial board in science journals, have published many papers and hold many patents.",institutionString:null,institution:{name:"Sheffield Hallam University",country:{name:"United Kingdom"}}},{id:"54525",title:"Prof.",name:"Abdul Latif",middleName:null,surname:"Ahmad",slug:"abdul-latif-ahmad",fullName:"Abdul Latif Ahmad",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:null},{id:"20567",title:"Prof.",name:"Ado",middleName:null,surname:"Jorio",slug:"ado-jorio",fullName:"Ado Jorio",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:{name:"Universidade Federal de Minas Gerais",country:{name:"Brazil"}}},{id:"47940",title:"Dr.",name:"Alberto",middleName:null,surname:"Mantovani",slug:"alberto-mantovani",fullName:"Alberto Mantovani",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:null},{id:"12392",title:"Mr.",name:"Alex",middleName:null,surname:"Lazinica",slug:"alex-lazinica",fullName:"Alex Lazinica",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/12392/images/7282_n.png",biography:"Alex Lazinica is the founder and CEO of IntechOpen. After obtaining a Master's degree in Mechanical Engineering, he continued his PhD studies in Robotics at the Vienna University of Technology. Here he worked as a robotic researcher with the university's Intelligent Manufacturing Systems Group as well as a guest researcher at various European universities, including the Swiss Federal Institute of Technology Lausanne (EPFL). During this time he published more than 20 scientific papers, gave presentations, served as a reviewer for major robotic journals and conferences and most importantly he co-founded and built the International Journal of Advanced Robotic Systems- world's first Open Access journal in the field of robotics. Starting this journal was a pivotal point in his career, since it was a pathway to founding IntechOpen - Open Access publisher focused on addressing academic researchers needs. Alex is a personification of IntechOpen key values being trusted, open and entrepreneurial. Today his focus is on defining the growth and development strategy for the company.",institutionString:null,institution:{name:"TU Wien",country:{name:"Austria"}}},{id:"19816",title:"Prof.",name:"Alexander",middleName:null,surname:"Kokorin",slug:"alexander-kokorin",fullName:"Alexander Kokorin",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/19816/images/1607_n.jpg",biography:"Alexander I. Kokorin: born: 1947, Moscow; DSc., PhD; Principal Research Fellow (Research Professor) of Department of Kinetics and Catalysis, N. Semenov Institute of Chemical Physics, Russian Academy of Sciences, Moscow.\r\nArea of research interests: physical chemistry of complex-organized molecular and nanosized systems, including polymer-metal complexes; the surface of doped oxide semiconductors. He is an expert in structural, absorptive, catalytic and photocatalytic properties, in structural organization and dynamic features of ionic liquids, in magnetic interactions between paramagnetic centers. The author or co-author of 3 books, over 200 articles and reviews in scientific journals and books. He is an actual member of the International EPR/ESR Society, European Society on Quantum Solar Energy Conversion, Moscow House of Scientists, of the Board of Moscow Physical Society.",institutionString:null,institution:{name:"Semenov Institute of Chemical Physics",country:{name:"Russia"}}},{id:"62389",title:"PhD.",name:"Ali Demir",middleName:null,surname:"Sezer",slug:"ali-demir-sezer",fullName:"Ali Demir Sezer",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/62389/images/3413_n.jpg",biography:"Dr. Ali Demir Sezer has a Ph.D. from Pharmaceutical Biotechnology at the Faculty of Pharmacy, University of Marmara (Turkey). He is the member of many Pharmaceutical Associations and acts as a reviewer of scientific journals and European projects under different research areas such as: drug delivery systems, nanotechnology and pharmaceutical biotechnology. Dr. Sezer is the author of many scientific publications in peer-reviewed journals and poster communications. Focus of his research activity is drug delivery, physico-chemical characterization and biological evaluation of biopolymers micro and nanoparticles as modified drug delivery system, and colloidal drug carriers (liposomes, nanoparticles etc.).",institutionString:null,institution:{name:"Marmara University",country:{name:"Turkey"}}},{id:"61051",title:"Prof.",name:"Andrea",middleName:null,surname:"Natale",slug:"andrea-natale",fullName:"Andrea Natale",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:null},{id:"100762",title:"Prof.",name:"Andrea",middleName:null,surname:"Natale",slug:"andrea-natale",fullName:"Andrea Natale",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:{name:"St David's Medical Center",country:{name:"United States of America"}}},{id:"107416",title:"Dr.",name:"Andrea",middleName:null,surname:"Natale",slug:"andrea-natale",fullName:"Andrea Natale",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:{name:"Texas Cardiac Arrhythmia",country:{name:"United States of America"}}},{id:"64434",title:"Dr.",name:"Angkoon",middleName:null,surname:"Phinyomark",slug:"angkoon-phinyomark",fullName:"Angkoon Phinyomark",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/64434/images/2619_n.jpg",biography:"My name is Angkoon Phinyomark. I received a B.Eng. degree in Computer Engineering with First Class Honors in 2008 from Prince of Songkla University, Songkhla, Thailand, where I received a Ph.D. degree in Electrical Engineering. My research interests are primarily in the area of biomedical signal processing and classification notably EMG (electromyography signal), EOG (electrooculography signal), and EEG (electroencephalography signal), image analysis notably breast cancer analysis and optical coherence tomography, and rehabilitation engineering. I became a student member of IEEE in 2008. During October 2011-March 2012, I had worked at School of Computer Science and Electronic Engineering, University of Essex, Colchester, Essex, United Kingdom. In addition, during a B.Eng. I had been a visiting research student at Faculty of Computer Science, University of Murcia, Murcia, Spain for three months.\n\nI have published over 40 papers during 5 years in refereed journals, books, and conference proceedings in the areas of electro-physiological signals processing and classification, notably EMG and EOG signals, fractal analysis, wavelet analysis, texture analysis, feature extraction and machine learning algorithms, and assistive and rehabilitative devices. I have several computer programming language certificates, i.e. Sun Certified Programmer for the Java 2 Platform 1.4 (SCJP), Microsoft Certified Professional Developer, Web Developer (MCPD), Microsoft Certified Technology Specialist, .NET Framework 2.0 Web (MCTS). I am a Reviewer for several refereed journals and international conferences, such as IEEE Transactions on Biomedical Engineering, IEEE Transactions on Industrial Electronics, Optic Letters, Measurement Science Review, and also a member of the International Advisory Committee for 2012 IEEE Business Engineering and Industrial Applications and 2012 IEEE Symposium on Business, Engineering and Industrial Applications.",institutionString:null,institution:{name:"Joseph Fourier University",country:{name:"France"}}},{id:"55578",title:"Dr.",name:"Antonio",middleName:null,surname:"Jurado-Navas",slug:"antonio-jurado-navas",fullName:"Antonio Jurado-Navas",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/55578/images/4574_n.png",biography:"Antonio Jurado-Navas received the M.S. degree (2002) and the Ph.D. degree (2009) in Telecommunication Engineering, both from the University of Málaga (Spain). He first worked as a consultant at Vodafone-Spain. From 2004 to 2011, he was a Research Assistant with the Communications Engineering Department at the University of Málaga. In 2011, he became an Assistant Professor in the same department. From 2012 to 2015, he was with Ericsson Spain, where he was working on geo-location\ntools for third generation mobile networks. Since 2015, he is a Marie-Curie fellow at the Denmark Technical University. His current research interests include the areas of mobile communication systems and channel modeling in addition to atmospheric optical communications, adaptive optics and statistics",institutionString:null,institution:{name:"University of Malaga",country:{name:"Spain"}}}],filtersByRegion:[{group:"region",caption:"North America",value:1,count:5774},{group:"region",caption:"Middle and South America",value:2,count:5239},{group:"region",caption:"Africa",value:3,count:1721},{group:"region",caption:"Asia",value:4,count:10411},{group:"region",caption:"Australia and Oceania",value:5,count:897},{group:"region",caption:"Europe",value:6,count:15810}],offset:12,limit:12,total:118377},chapterEmbeded:{data:{}},editorApplication:{success:null,errors:{}},ofsBooks:{filterParams:{topicId:"16"},books:[{type:"book",id:"9816",title:"Idiopathic Pulmonary Fibrosis",subtitle:null,isOpenForSubmission:!0,hash:"365bb9762ba33db2d07e677690af1772",slug:null,bookSignature:"Dr. Salim Surani and Dr. Venkat Rajasurya",coverURL:"https://cdn.intechopen.com/books/images_new/9816.jpg",editedByType:null,editors:[{id:"15654",title:"Dr.",name:"Salim",surname:"Surani",slug:"salim-surani",fullName:"Salim Surani"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10231",title:"Proton Therapy",subtitle:null,isOpenForSubmission:!0,hash:"f4a9009287953c8d1d89f0fa9b7597b0",slug:null,bookSignature:"",coverURL:"https://cdn.intechopen.com/books/images_new/10231.jpg",editedByType:null,editors:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10343",title:"Ocular Hypertension",subtitle:null,isOpenForSubmission:!0,hash:"0ff71cc7e0d9f394f41162c0c825588a",slug:null,bookSignature:"Prof. Michele Lanza",coverURL:"https://cdn.intechopen.com/books/images_new/10343.jpg",editedByType:null,editors:[{id:"240088",title:"Prof.",name:"Michele",surname:"Lanza",slug:"michele-lanza",fullName:"Michele Lanza"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10704",title:"Cardiac Arrhythmias - Translational Approach from Pathophysiology to Advanced Care",subtitle:null,isOpenForSubmission:!0,hash:"0e5d67464d929fda6d8c83ec20c4138a",slug:null,bookSignature:"Dr. Endre Zima",coverURL:"https://cdn.intechopen.com/books/images_new/10704.jpg",editedByType:null,editors:[{id:"201263",title:"Dr.",name:"Endre",surname:"Zima",slug:"endre-zima",fullName:"Endre Zima"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10705",title:"Healthcare Access",subtitle:null,isOpenForSubmission:!0,hash:"e8e9561a91e5f7771932aa5d49c3b687",slug:null,bookSignature:"Prof. Amit Agrawal and Dr. Srinivas Kosgi",coverURL:"https://cdn.intechopen.com/books/images_new/10705.jpg",editedByType:null,editors:[{id:"100142",title:"Prof.",name:"Amit",surname:"Agrawal",slug:"amit-agrawal",fullName:"Amit Agrawal"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10706",title:"Fighting the COVID-19 Pandemic",subtitle:null,isOpenForSubmission:!0,hash:"1a5246f0b6ba4f0e9ad1fbfa4134c598",slug:null,bookSignature:"Dr. Manal Mohammad Baddour",coverURL:"https://cdn.intechopen.com/books/images_new/10706.jpg",editedByType:null,editors:[{id:"174598",title:"Dr.",name:"Manal Mohammad",surname:"Baddour",slug:"manal-mohammad-baddour",fullName:"Manal Mohammad Baddour"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10707",title:"Primary Care",subtitle:null,isOpenForSubmission:!0,hash:"bdb1aeb61b1eb116c1bdb09d25593686",slug:null,bookSignature:"",coverURL:"https://cdn.intechopen.com/books/images_new/10707.jpg",editedByType:null,editors:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10708",title:"Topics in Regional Anesthesia",subtitle:null,isOpenForSubmission:!0,hash:"264f7f37033b4867cace7912287fccaa",slug:null,bookSignature:"Prof. Víctor M. Whizar-Lugo and Dr. José Ramón Saucillo-Osuna",coverURL:"https://cdn.intechopen.com/books/images_new/10708.jpg",editedByType:null,editors:[{id:"169249",title:"Prof.",name:"Víctor M.",surname:"Whizar-Lugo",slug:"victor-m.-whizar-lugo",fullName:"Víctor M. Whizar-Lugo"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10709",title:"Heart Valve Surgery",subtitle:null,isOpenForSubmission:!0,hash:"cb3479fd272d968ee7eee95ae09ea9db",slug:null,bookSignature:"",coverURL:"https://cdn.intechopen.com/books/images_new/10709.jpg",editedByType:null,editors:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10710",title:"Recent Advances in the Treatment of Orofacial Clefts",subtitle:null,isOpenForSubmission:!0,hash:"ec438b5e4be44dc63870c1ace6a56ed2",slug:null,bookSignature:"Dr. Marcos Roberto Tovani Palone",coverURL:"https://cdn.intechopen.com/books/images_new/10710.jpg",editedByType:null,editors:[{id:"221178",title:"Dr.",name:"Marcos Roberto",surname:"Tovani Palone",slug:"marcos-roberto-tovani-palone",fullName:"Marcos Roberto Tovani Palone"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10711",title:"Arthroscopy",subtitle:null,isOpenForSubmission:!0,hash:"afa83f11ba2442e7612f5b8c6aa3c659",slug:null,bookSignature:"M.D. Carlos Suarez-Ahedo",coverURL:"https://cdn.intechopen.com/books/images_new/10711.jpg",editedByType:null,editors:[{id:"235976",title:"M.D.",name:"Carlos",surname:"Suarez-Ahedo",slug:"carlos-suarez-ahedo",fullName:"Carlos Suarez-Ahedo"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10712",title:"Thrombectomy",subtitle:null,isOpenForSubmission:!0,hash:"853e71d74c3dd5007277d3770e639d47",slug:null,bookSignature:"",coverURL:"https://cdn.intechopen.com/books/images_new/10712.jpg",editedByType:null,editors:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}],filtersByTopic:[{group:"topic",caption:"Agricultural and Biological Sciences",value:5,count:18},{group:"topic",caption:"Biochemistry, Genetics and Molecular Biology",value:6,count:5},{group:"topic",caption:"Business, Management and Economics",value:7,count:2},{group:"topic",caption:"Chemistry",value:8,count:8},{group:"topic",caption:"Computer and Information Science",value:9,count:6},{group:"topic",caption:"Earth and Planetary Sciences",value:10,count:7},{group:"topic",caption:"Engineering",value:11,count:20},{group:"topic",caption:"Environmental Sciences",value:12,count:2},{group:"topic",caption:"Immunology and Microbiology",value:13,count:4},{group:"topic",caption:"Materials Science",value:14,count:5},{group:"topic",caption:"Mathematics",value:15,count:1},{group:"topic",caption:"Medicine",value:16,count:25},{group:"topic",caption:"Neuroscience",value:18,count:2},{group:"topic",caption:"Pharmacology, Toxicology and Pharmaceutical Science",value:19,count:3},{group:"topic",caption:"Physics",value:20,count:3},{group:"topic",caption:"Psychology",value:21,count:4},{group:"topic",caption:"Robotics",value:22,count:1},{group:"topic",caption:"Social Sciences",value:23,count:3},{group:"topic",caption:"Technology",value:24,count:1},{group:"topic",caption:"Veterinary Medicine and Science",value:25,count:1}],offset:12,limit:12,total:51},popularBooks:{featuredBooks:[{type:"book",id:"9521",title:"Antimicrobial Resistance",subtitle:"A One Health Perspective",isOpenForSubmission:!1,hash:"30949e78832e1afba5606634b52056ab",slug:"antimicrobial-resistance-a-one-health-perspective",bookSignature:"Mihai Mareș, Swee Hua Erin Lim, Kok-Song Lai and Romeo-Teodor Cristina",coverURL:"https://cdn.intechopen.com/books/images_new/9521.jpg",editors:[{id:"88785",title:"Prof.",name:"Mihai",middleName:null,surname:"Mares",slug:"mihai-mares",fullName:"Mihai Mares"}],equalEditorOne:{id:"190224",title:"Dr.",name:"Swee Hua Erin",middleName:null,surname:"Lim",slug:"swee-hua-erin-lim",fullName:"Swee Hua Erin Lim",profilePictureURL:"https://mts.intechopen.com/storage/users/190224/images/system/190224.png",biography:"Dr. Erin Lim is presently working as an Assistant Professor in the Division of Health Sciences, Abu Dhabi Women\\'s College, Higher Colleges of Technology in Abu Dhabi, United Arab Emirates and is affiliated as an Associate Professor to Perdana University-Royal College of Surgeons in Ireland, Selangor, Malaysia. She obtained her Ph.D. from Universiti Putra Malaysia in 2010 with a National Science Fellowship awarded from the Ministry of Science, Technology and Innovation Malaysia and has been actively involved in research ever since. Her main research interests include analysis of carriage and transmission of multidrug resistant bacteria in non-conventional settings, besides an interest in natural products for antimicrobial testing. She is heavily involved in the elucidation of mechanisms of reversal of resistance in bacteria in addition to investigating the immunological analyses of diseases, development of vaccination and treatment models in animals. She hopes her work will support the discovery of therapeutics in the clinical setting and assist in the combat against the burden of antibiotic resistance.",institutionString:"Abu Dhabi Women’s College",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"3",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"Perdana University",institutionURL:null,country:{name:"Malaysia"}}},equalEditorTwo:{id:"221544",title:"Dr.",name:"Kok-Song",middleName:null,surname:"Lai",slug:"kok-song-lai",fullName:"Kok-Song Lai",profilePictureURL:"https://mts.intechopen.com/storage/users/221544/images/system/221544.jpeg",biography:"Dr. Lai Kok Song is an Assistant Professor in the Division of Health Sciences, Abu Dhabi Women\\'s College, Higher Colleges of Technology in Abu Dhabi, United Arab Emirates. He obtained his Ph.D. in Biological Sciences from Nara Institute of Science and Technology, Japan in 2012. Prior to his academic appointment, Dr. Lai worked as a Senior Scientist at the Ministry of Science, Technology and Innovation, Malaysia. His current research areas include antimicrobial resistance and plant-pathogen interaction. His particular interest lies in the study of the antimicrobial mechanism via membrane disruption of essential oils against multi-drug resistance bacteria through various biochemical, molecular and proteomic approaches. Ultimately, he hopes to uncover and determine novel biomarkers related to antibiotic resistance that can be developed into new therapeutic strategies.",institutionString:"Higher Colleges of Technology",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"8",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"Higher Colleges of Technology",institutionURL:null,country:{name:"United Arab Emirates"}}},equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"10020",title:"Operations Management",subtitle:"Emerging Trend in the Digital Era",isOpenForSubmission:!1,hash:"526f0dbdc7e4d85b82ce8383ab894b4c",slug:"operations-management-emerging-trend-in-the-digital-era",bookSignature:"Antonella Petrillo, Fabio De Felice, Germano Lambert-Torres and Erik Bonaldi",coverURL:"https://cdn.intechopen.com/books/images_new/10020.jpg",editors:[{id:"181603",title:"Dr.",name:"Antonella",middleName:null,surname:"Petrillo",slug:"antonella-petrillo",fullName:"Antonella Petrillo"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9560",title:"Creativity",subtitle:"A Force to Innovation",isOpenForSubmission:!1,hash:"58f740bc17807d5d88d647c525857b11",slug:"creativity-a-force-to-innovation",bookSignature:"Pooja Jain",coverURL:"https://cdn.intechopen.com/books/images_new/9560.jpg",editors:[{id:"316765",title:"Dr.",name:"Pooja",middleName:null,surname:"Jain",slug:"pooja-jain",fullName:"Pooja Jain"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"10192",title:"Background and Management of Muscular Atrophy",subtitle:null,isOpenForSubmission:!1,hash:"eca24028d89912b5efea56e179dff089",slug:"background-and-management-of-muscular-atrophy",bookSignature:"Julianna Cseri",coverURL:"https://cdn.intechopen.com/books/images_new/10192.jpg",editors:[{id:"135579",title:"Dr.",name:"Julianna",middleName:null,surname:"Cseri",slug:"julianna-cseri",fullName:"Julianna Cseri"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9243",title:"Coastal Environments",subtitle:null,isOpenForSubmission:!1,hash:"8e05e5f631e935eef366980f2e28295d",slug:"coastal-environments",bookSignature:"Yuanzhi Zhang and X. San Liang",coverURL:"https://cdn.intechopen.com/books/images_new/9243.jpg",editors:[{id:"77597",title:"Prof.",name:"Yuanzhi",middleName:null,surname:"Zhang",slug:"yuanzhi-zhang",fullName:"Yuanzhi Zhang"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9385",title:"Renewable Energy",subtitle:"Technologies and Applications",isOpenForSubmission:!1,hash:"a6b446d19166f17f313008e6c056f3d8",slug:"renewable-energy-technologies-and-applications",bookSignature:"Tolga Taner, Archana Tiwari and Taha Selim Ustun",coverURL:"https://cdn.intechopen.com/books/images_new/9385.jpg",editors:[{id:"197240",title:"Associate Prof.",name:"Tolga",middleName:null,surname:"Taner",slug:"tolga-taner",fullName:"Tolga Taner"}],equalEditorOne:{id:"186791",title:"Dr.",name:"Archana",middleName:null,surname:"Tiwari",slug:"archana-tiwari",fullName:"Archana Tiwari",profilePictureURL:"https://mts.intechopen.com/storage/users/186791/images/system/186791.jpg",biography:"Dr. Archana Tiwari is Associate Professor at Amity University, India. Her research interests include renewable sources of energy from microalgae and further utilizing the residual biomass for the generation of value-added products, bioremediation through microalgae and microbial consortium, antioxidative enzymes and stress, and nutraceuticals from microalgae. She has been working on algal biotechnology for the last two decades. She has published her research in many international journals and has authored many books and chapters with renowned publishing houses. She has also delivered talks as an invited speaker at many national and international conferences. Dr. Tiwari is the recipient of several awards including Researcher of the Year and Distinguished Scientist.",institutionString:"Amity University",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"3",totalChapterViews:"0",totalEditedBooks:"1",institution:{name:"Amity University",institutionURL:null,country:{name:"India"}}},equalEditorTwo:{id:"197609",title:"Prof.",name:"Taha Selim",middleName:null,surname:"Ustun",slug:"taha-selim-ustun",fullName:"Taha Selim Ustun",profilePictureURL:"https://mts.intechopen.com/storage/users/197609/images/system/197609.jpeg",biography:"Dr. Taha Selim Ustun received a Ph.D. in Electrical Engineering from Victoria University, Melbourne, Australia. He is a researcher with the Fukushima Renewable Energy Institute, AIST (FREA), where he leads the Smart Grid Cybersecurity Laboratory. Prior to that, he was a faculty member with the School of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA. His current research interests include power systems protection, communication in power networks, distributed generation, microgrids, electric vehicle integration, and cybersecurity in smart grids. He serves on the editorial boards of IEEE Access, IEEE Transactions on Industrial Informatics, Energies, Electronics, Electricity, World Electric Vehicle and Information journals. Dr. Ustun is a member of the IEEE 2004 and 2800, IEC Renewable Energy Management WG 8, and IEC TC 57 WG17. He has been invited to run specialist courses in Africa, India, and China. He has delivered talks for the Qatar Foundation, the World Energy Council, the Waterloo Global Science Initiative, and the European Union Energy Initiative (EUEI). His research has attracted funding from prestigious programs in Japan, Australia, the European Union, and North America.",institutionString:"Fukushima Renewable Energy Institute, AIST (FREA)",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"1",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"National Institute of Advanced Industrial Science and Technology",institutionURL:null,country:{name:"Japan"}}},equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8985",title:"Natural Resources Management and Biological Sciences",subtitle:null,isOpenForSubmission:!1,hash:"5c2e219a6c021a40b5a20c041dea88c4",slug:"natural-resources-management-and-biological-sciences",bookSignature:"Edward R. Rhodes and Humood Naser",coverURL:"https://cdn.intechopen.com/books/images_new/8985.jpg",editors:[{id:"280886",title:"Prof.",name:"Edward R",middleName:null,surname:"Rhodes",slug:"edward-r-rhodes",fullName:"Edward R Rhodes"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"10065",title:"Wavelet Theory",subtitle:null,isOpenForSubmission:!1,hash:"d8868e332169597ba2182d9b004d60de",slug:"wavelet-theory",bookSignature:"Somayeh Mohammady",coverURL:"https://cdn.intechopen.com/books/images_new/10065.jpg",editors:[{id:"109280",title:"Dr.",name:"Somayeh",middleName:null,surname:"Mohammady",slug:"somayeh-mohammady",fullName:"Somayeh Mohammady"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9644",title:"Glaciers and the Polar Environment",subtitle:null,isOpenForSubmission:!1,hash:"e8cfdc161794e3753ced54e6ff30873b",slug:"glaciers-and-the-polar-environment",bookSignature:"Masaki Kanao, Danilo Godone and Niccolò Dematteis",coverURL:"https://cdn.intechopen.com/books/images_new/9644.jpg",editors:[{id:"51959",title:"Dr.",name:"Masaki",middleName:null,surname:"Kanao",slug:"masaki-kanao",fullName:"Masaki Kanao"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9550",title:"Entrepreneurship",subtitle:"Contemporary Issues",isOpenForSubmission:!1,hash:"9b4ac1ee5b743abf6f88495452b1e5e7",slug:"entrepreneurship-contemporary-issues",bookSignature:"Mladen Turuk",coverURL:"https://cdn.intechopen.com/books/images_new/9550.jpg",editors:[{id:"319755",title:"Prof.",name:"Mladen",middleName:null,surname:"Turuk",slug:"mladen-turuk",fullName:"Mladen Turuk"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9027",title:"Human Blood Group Systems and Haemoglobinopathies",subtitle:null,isOpenForSubmission:!1,hash:"d00d8e40b11cfb2547d1122866531c7e",slug:"human-blood-group-systems-and-haemoglobinopathies",bookSignature:"Osaro Erhabor and Anjana Munshi",coverURL:"https://cdn.intechopen.com/books/images_new/9027.jpg",editors:[{id:"35140",title:null,name:"Osaro",middleName:null,surname:"Erhabor",slug:"osaro-erhabor",fullName:"Osaro Erhabor"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8558",title:"Aerodynamics",subtitle:null,isOpenForSubmission:!1,hash:"db7263fc198dfb539073ba0260a7f1aa",slug:"aerodynamics",bookSignature:"Mofid Gorji-Bandpy and Aly-Mousaad Aly",coverURL:"https://cdn.intechopen.com/books/images_new/8558.jpg",editors:[{id:"35542",title:"Prof.",name:"Mofid",middleName:null,surname:"Gorji-Bandpy",slug:"mofid-gorji-bandpy",fullName:"Mofid Gorji-Bandpy"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}}],offset:12,limit:12,total:5249},hotBookTopics:{hotBooks:[],offset:0,limit:12,total:null},publish:{},publishingProposal:{success:null,errors:{}},books:{featuredBooks:[{type:"book",id:"9521",title:"Antimicrobial Resistance",subtitle:"A One Health Perspective",isOpenForSubmission:!1,hash:"30949e78832e1afba5606634b52056ab",slug:"antimicrobial-resistance-a-one-health-perspective",bookSignature:"Mihai Mareș, Swee Hua Erin Lim, Kok-Song Lai and Romeo-Teodor Cristina",coverURL:"https://cdn.intechopen.com/books/images_new/9521.jpg",editors:[{id:"88785",title:"Prof.",name:"Mihai",middleName:null,surname:"Mares",slug:"mihai-mares",fullName:"Mihai Mares"}],equalEditorOne:{id:"190224",title:"Dr.",name:"Swee Hua Erin",middleName:null,surname:"Lim",slug:"swee-hua-erin-lim",fullName:"Swee Hua Erin Lim",profilePictureURL:"https://mts.intechopen.com/storage/users/190224/images/system/190224.png",biography:"Dr. Erin Lim is presently working as an Assistant Professor in the Division of Health Sciences, Abu Dhabi Women\\'s College, Higher Colleges of Technology in Abu Dhabi, United Arab Emirates and is affiliated as an Associate Professor to Perdana University-Royal College of Surgeons in Ireland, Selangor, Malaysia. She obtained her Ph.D. from Universiti Putra Malaysia in 2010 with a National Science Fellowship awarded from the Ministry of Science, Technology and Innovation Malaysia and has been actively involved in research ever since. Her main research interests include analysis of carriage and transmission of multidrug resistant bacteria in non-conventional settings, besides an interest in natural products for antimicrobial testing. She is heavily involved in the elucidation of mechanisms of reversal of resistance in bacteria in addition to investigating the immunological analyses of diseases, development of vaccination and treatment models in animals. She hopes her work will support the discovery of therapeutics in the clinical setting and assist in the combat against the burden of antibiotic resistance.",institutionString:"Abu Dhabi Women’s College",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"3",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"Perdana University",institutionURL:null,country:{name:"Malaysia"}}},equalEditorTwo:{id:"221544",title:"Dr.",name:"Kok-Song",middleName:null,surname:"Lai",slug:"kok-song-lai",fullName:"Kok-Song Lai",profilePictureURL:"https://mts.intechopen.com/storage/users/221544/images/system/221544.jpeg",biography:"Dr. Lai Kok Song is an Assistant Professor in the Division of Health Sciences, Abu Dhabi Women\\'s College, Higher Colleges of Technology in Abu Dhabi, United Arab Emirates. He obtained his Ph.D. in Biological Sciences from Nara Institute of Science and Technology, Japan in 2012. Prior to his academic appointment, Dr. Lai worked as a Senior Scientist at the Ministry of Science, Technology and Innovation, Malaysia. His current research areas include antimicrobial resistance and plant-pathogen interaction. His particular interest lies in the study of the antimicrobial mechanism via membrane disruption of essential oils against multi-drug resistance bacteria through various biochemical, molecular and proteomic approaches. Ultimately, he hopes to uncover and determine novel biomarkers related to antibiotic resistance that can be developed into new therapeutic strategies.",institutionString:"Higher Colleges of Technology",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"8",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"Higher Colleges of Technology",institutionURL:null,country:{name:"United Arab Emirates"}}},equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"10020",title:"Operations Management",subtitle:"Emerging Trend in the Digital Era",isOpenForSubmission:!1,hash:"526f0dbdc7e4d85b82ce8383ab894b4c",slug:"operations-management-emerging-trend-in-the-digital-era",bookSignature:"Antonella Petrillo, Fabio De Felice, Germano Lambert-Torres and Erik Bonaldi",coverURL:"https://cdn.intechopen.com/books/images_new/10020.jpg",editors:[{id:"181603",title:"Dr.",name:"Antonella",middleName:null,surname:"Petrillo",slug:"antonella-petrillo",fullName:"Antonella Petrillo"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9560",title:"Creativity",subtitle:"A Force to Innovation",isOpenForSubmission:!1,hash:"58f740bc17807d5d88d647c525857b11",slug:"creativity-a-force-to-innovation",bookSignature:"Pooja Jain",coverURL:"https://cdn.intechopen.com/books/images_new/9560.jpg",editors:[{id:"316765",title:"Dr.",name:"Pooja",middleName:null,surname:"Jain",slug:"pooja-jain",fullName:"Pooja Jain"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9385",title:"Renewable Energy",subtitle:"Technologies and Applications",isOpenForSubmission:!1,hash:"a6b446d19166f17f313008e6c056f3d8",slug:"renewable-energy-technologies-and-applications",bookSignature:"Tolga Taner, Archana Tiwari and Taha Selim Ustun",coverURL:"https://cdn.intechopen.com/books/images_new/9385.jpg",editors:[{id:"197240",title:"Associate Prof.",name:"Tolga",middleName:null,surname:"Taner",slug:"tolga-taner",fullName:"Tolga Taner"}],equalEditorOne:{id:"186791",title:"Dr.",name:"Archana",middleName:null,surname:"Tiwari",slug:"archana-tiwari",fullName:"Archana Tiwari",profilePictureURL:"https://mts.intechopen.com/storage/users/186791/images/system/186791.jpg",biography:"Dr. Archana Tiwari is Associate Professor at Amity University, India. Her research interests include renewable sources of energy from microalgae and further utilizing the residual biomass for the generation of value-added products, bioremediation through microalgae and microbial consortium, antioxidative enzymes and stress, and nutraceuticals from microalgae. She has been working on algal biotechnology for the last two decades. She has published her research in many international journals and has authored many books and chapters with renowned publishing houses. She has also delivered talks as an invited speaker at many national and international conferences. Dr. Tiwari is the recipient of several awards including Researcher of the Year and Distinguished Scientist.",institutionString:"Amity University",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"3",totalChapterViews:"0",totalEditedBooks:"1",institution:{name:"Amity University",institutionURL:null,country:{name:"India"}}},equalEditorTwo:{id:"197609",title:"Prof.",name:"Taha Selim",middleName:null,surname:"Ustun",slug:"taha-selim-ustun",fullName:"Taha Selim Ustun",profilePictureURL:"https://mts.intechopen.com/storage/users/197609/images/system/197609.jpeg",biography:"Dr. Taha Selim Ustun received a Ph.D. in Electrical Engineering from Victoria University, Melbourne, Australia. He is a researcher with the Fukushima Renewable Energy Institute, AIST (FREA), where he leads the Smart Grid Cybersecurity Laboratory. Prior to that, he was a faculty member with the School of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, PA, USA. His current research interests include power systems protection, communication in power networks, distributed generation, microgrids, electric vehicle integration, and cybersecurity in smart grids. He serves on the editorial boards of IEEE Access, IEEE Transactions on Industrial Informatics, Energies, Electronics, Electricity, World Electric Vehicle and Information journals. Dr. Ustun is a member of the IEEE 2004 and 2800, IEC Renewable Energy Management WG 8, and IEC TC 57 WG17. He has been invited to run specialist courses in Africa, India, and China. He has delivered talks for the Qatar Foundation, the World Energy Council, the Waterloo Global Science Initiative, and the European Union Energy Initiative (EUEI). His research has attracted funding from prestigious programs in Japan, Australia, the European Union, and North America.",institutionString:"Fukushima Renewable Energy Institute, AIST (FREA)",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"1",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"National Institute of Advanced Industrial Science and Technology",institutionURL:null,country:{name:"Japan"}}},equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8985",title:"Natural Resources Management and Biological Sciences",subtitle:null,isOpenForSubmission:!1,hash:"5c2e219a6c021a40b5a20c041dea88c4",slug:"natural-resources-management-and-biological-sciences",bookSignature:"Edward R. Rhodes and Humood Naser",coverURL:"https://cdn.intechopen.com/books/images_new/8985.jpg",editors:[{id:"280886",title:"Prof.",name:"Edward R",middleName:null,surname:"Rhodes",slug:"edward-r-rhodes",fullName:"Edward R Rhodes"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"10192",title:"Background and Management of Muscular Atrophy",subtitle:null,isOpenForSubmission:!1,hash:"eca24028d89912b5efea56e179dff089",slug:"background-and-management-of-muscular-atrophy",bookSignature:"Julianna Cseri",coverURL:"https://cdn.intechopen.com/books/images_new/10192.jpg",editors:[{id:"135579",title:"Dr.",name:"Julianna",middleName:null,surname:"Cseri",slug:"julianna-cseri",fullName:"Julianna Cseri"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"10065",title:"Wavelet Theory",subtitle:null,isOpenForSubmission:!1,hash:"d8868e332169597ba2182d9b004d60de",slug:"wavelet-theory",bookSignature:"Somayeh Mohammady",coverURL:"https://cdn.intechopen.com/books/images_new/10065.jpg",editors:[{id:"109280",title:"Dr.",name:"Somayeh",middleName:null,surname:"Mohammady",slug:"somayeh-mohammady",fullName:"Somayeh Mohammady"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9243",title:"Coastal Environments",subtitle:null,isOpenForSubmission:!1,hash:"8e05e5f631e935eef366980f2e28295d",slug:"coastal-environments",bookSignature:"Yuanzhi Zhang and X. San Liang",coverURL:"https://cdn.intechopen.com/books/images_new/9243.jpg",editors:[{id:"77597",title:"Prof.",name:"Yuanzhi",middleName:null,surname:"Zhang",slug:"yuanzhi-zhang",fullName:"Yuanzhi Zhang"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9644",title:"Glaciers and the Polar Environment",subtitle:null,isOpenForSubmission:!1,hash:"e8cfdc161794e3753ced54e6ff30873b",slug:"glaciers-and-the-polar-environment",bookSignature:"Masaki Kanao, Danilo Godone and Niccolò Dematteis",coverURL:"https://cdn.intechopen.com/books/images_new/9644.jpg",editors:[{id:"51959",title:"Dr.",name:"Masaki",middleName:null,surname:"Kanao",slug:"masaki-kanao",fullName:"Masaki Kanao"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7847",title:"Medical Toxicology",subtitle:null,isOpenForSubmission:!1,hash:"db9b65bea093de17a0855a1b27046247",slug:"medical-toxicology",bookSignature:"Pınar Erkekoglu and Tomohisa Ogawa",coverURL:"https://cdn.intechopen.com/books/images_new/7847.jpg",editors:[{id:"109978",title:"Prof.",name:"Pınar",middleName:null,surname:"Erkekoglu",slug:"pinar-erkekoglu",fullName:"Pınar Erkekoglu"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}}],latestBooks:[{type:"book",id:"9243",title:"Coastal Environments",subtitle:null,isOpenForSubmission:!1,hash:"8e05e5f631e935eef366980f2e28295d",slug:"coastal-environments",bookSignature:"Yuanzhi Zhang and X. San Liang",coverURL:"https://cdn.intechopen.com/books/images_new/9243.jpg",editedByType:"Edited by",editors:[{id:"77597",title:"Prof.",name:"Yuanzhi",middleName:null,surname:"Zhang",slug:"yuanzhi-zhang",fullName:"Yuanzhi Zhang"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10020",title:"Operations Management",subtitle:"Emerging Trend in the Digital Era",isOpenForSubmission:!1,hash:"526f0dbdc7e4d85b82ce8383ab894b4c",slug:"operations-management-emerging-trend-in-the-digital-era",bookSignature:"Antonella Petrillo, Fabio De Felice, Germano Lambert-Torres and Erik Bonaldi",coverURL:"https://cdn.intechopen.com/books/images_new/10020.jpg",editedByType:"Edited by",editors:[{id:"181603",title:"Dr.",name:"Antonella",middleName:null,surname:"Petrillo",slug:"antonella-petrillo",fullName:"Antonella Petrillo"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9521",title:"Antimicrobial Resistance",subtitle:"A One Health Perspective",isOpenForSubmission:!1,hash:"30949e78832e1afba5606634b52056ab",slug:"antimicrobial-resistance-a-one-health-perspective",bookSignature:"Mihai Mareș, Swee Hua Erin Lim, Kok-Song Lai and Romeo-Teodor Cristina",coverURL:"https://cdn.intechopen.com/books/images_new/9521.jpg",editedByType:"Edited by",editors:[{id:"88785",title:"Prof.",name:"Mihai",middleName:null,surname:"Mares",slug:"mihai-mares",fullName:"Mihai Mares"}],equalEditorOne:{id:"190224",title:"Dr.",name:"Swee Hua Erin",middleName:null,surname:"Lim",slug:"swee-hua-erin-lim",fullName:"Swee Hua Erin Lim",profilePictureURL:"https://mts.intechopen.com/storage/users/190224/images/system/190224.png",biography:"Dr. Erin Lim is presently working as an Assistant Professor in the Division of Health Sciences, Abu Dhabi Women\\'s College, Higher Colleges of Technology in Abu Dhabi, United Arab Emirates and is affiliated as an Associate Professor to Perdana University-Royal College of Surgeons in Ireland, Selangor, Malaysia. She obtained her Ph.D. from Universiti Putra Malaysia in 2010 with a National Science Fellowship awarded from the Ministry of Science, Technology and Innovation Malaysia and has been actively involved in research ever since. Her main research interests include analysis of carriage and transmission of multidrug resistant bacteria in non-conventional settings, besides an interest in natural products for antimicrobial testing. She is heavily involved in the elucidation of mechanisms of reversal of resistance in bacteria in addition to investigating the immunological analyses of diseases, development of vaccination and treatment models in animals. She hopes her work will support the discovery of therapeutics in the clinical setting and assist in the combat against the burden of antibiotic resistance.",institutionString:"Abu Dhabi Women’s College",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"3",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"Perdana University",institutionURL:null,country:{name:"Malaysia"}}},equalEditorTwo:{id:"221544",title:"Dr.",name:"Kok-Song",middleName:null,surname:"Lai",slug:"kok-song-lai",fullName:"Kok-Song Lai",profilePictureURL:"https://mts.intechopen.com/storage/users/221544/images/system/221544.jpeg",biography:"Dr. Lai Kok Song is an Assistant Professor in the Division of Health Sciences, Abu Dhabi Women\\'s College, Higher Colleges of Technology in Abu Dhabi, United Arab Emirates. He obtained his Ph.D. in Biological Sciences from Nara Institute of Science and Technology, Japan in 2012. Prior to his academic appointment, Dr. Lai worked as a Senior Scientist at the Ministry of Science, Technology and Innovation, Malaysia. His current research areas include antimicrobial resistance and plant-pathogen interaction. His particular interest lies in the study of the antimicrobial mechanism via membrane disruption of essential oils against multi-drug resistance bacteria through various biochemical, molecular and proteomic approaches. Ultimately, he hopes to uncover and determine novel biomarkers related to antibiotic resistance that can be developed into new therapeutic strategies.",institutionString:"Higher Colleges of Technology",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"8",totalChapterViews:"0",totalEditedBooks:"0",institution:{name:"Higher Colleges of Technology",institutionURL:null,country:{name:"United Arab Emirates"}}},equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9560",title:"Creativity",subtitle:"A Force to Innovation",isOpenForSubmission:!1,hash:"58f740bc17807d5d88d647c525857b11",slug:"creativity-a-force-to-innovation",bookSignature:"Pooja Jain",coverURL:"https://cdn.intechopen.com/books/images_new/9560.jpg",editedByType:"Edited by",editors:[{id:"316765",title:"Dr.",name:"Pooja",middleName:null,surname:"Jain",slug:"pooja-jain",fullName:"Pooja Jain"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9669",title:"Recent Advances in Rice Research",subtitle:null,isOpenForSubmission:!1,hash:"12b06cc73e89af1e104399321cc16a75",slug:"recent-advances-in-rice-research",bookSignature:"Mahmood-ur- Rahman Ansari",coverURL:"https://cdn.intechopen.com/books/images_new/9669.jpg",editedByType:"Edited by",editors:[{id:"185476",title:"Dr.",name:"Mahmood-Ur-",middleName:null,surname:"Rahman Ansari",slug:"mahmood-ur-rahman-ansari",fullName:"Mahmood-Ur- Rahman Ansari"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10192",title:"Background and Management of Muscular Atrophy",subtitle:null,isOpenForSubmission:!1,hash:"eca24028d89912b5efea56e179dff089",slug:"background-and-management-of-muscular-atrophy",bookSignature:"Julianna Cseri",coverURL:"https://cdn.intechopen.com/books/images_new/10192.jpg",editedByType:"Edited by",editors:[{id:"135579",title:"Dr.",name:"Julianna",middleName:null,surname:"Cseri",slug:"julianna-cseri",fullName:"Julianna Cseri"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9550",title:"Entrepreneurship",subtitle:"Contemporary Issues",isOpenForSubmission:!1,hash:"9b4ac1ee5b743abf6f88495452b1e5e7",slug:"entrepreneurship-contemporary-issues",bookSignature:"Mladen Turuk",coverURL:"https://cdn.intechopen.com/books/images_new/9550.jpg",editedByType:"Edited by",editors:[{id:"319755",title:"Prof.",name:"Mladen",middleName:null,surname:"Turuk",slug:"mladen-turuk",fullName:"Mladen Turuk"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10065",title:"Wavelet Theory",subtitle:null,isOpenForSubmission:!1,hash:"d8868e332169597ba2182d9b004d60de",slug:"wavelet-theory",bookSignature:"Somayeh Mohammady",coverURL:"https://cdn.intechopen.com/books/images_new/10065.jpg",editedByType:"Edited by",editors:[{id:"109280",title:"Dr.",name:"Somayeh",middleName:null,surname:"Mohammady",slug:"somayeh-mohammady",fullName:"Somayeh Mohammady"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9313",title:"Clay Science and Technology",subtitle:null,isOpenForSubmission:!1,hash:"6fa7e70396ff10620e032bb6cfa6fb72",slug:"clay-science-and-technology",bookSignature:"Gustavo Morari Do Nascimento",coverURL:"https://cdn.intechopen.com/books/images_new/9313.jpg",editedByType:"Edited by",editors:[{id:"7153",title:"Prof.",name:"Gustavo",middleName:null,surname:"Morari Do Nascimento",slug:"gustavo-morari-do-nascimento",fullName:"Gustavo Morari Do Nascimento"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9888",title:"Nuclear Power Plants",subtitle:"The Processes from the Cradle to the Grave",isOpenForSubmission:!1,hash:"c2c8773e586f62155ab8221ebb72a849",slug:"nuclear-power-plants-the-processes-from-the-cradle-to-the-grave",bookSignature:"Nasser Awwad",coverURL:"https://cdn.intechopen.com/books/images_new/9888.jpg",editedByType:"Edited by",editors:[{id:"145209",title:"Prof.",name:"Nasser",middleName:"S",surname:"Awwad",slug:"nasser-awwad",fullName:"Nasser Awwad"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}]},subject:{topic:{id:"738",title:"Electromechanics",slug:"electromechanics",parent:{title:"Electrical and Electronic Engineering",slug:"electrical-and-electronic-engineering"},numberOfBooks:6,numberOfAuthorsAndEditors:148,numberOfWosCitations:86,numberOfCrossrefCitations:38,numberOfDimensionsCitations:98,videoUrl:null,fallbackUrl:null,description:null},booksByTopicFilter:{topicSlug:"electromechanics",sort:"-publishedDate",limit:12,offset:0},booksByTopicCollection:[{type:"book",id:"8899",title:"Modelling and Control of Switched Reluctance Machines",subtitle:null,isOpenForSubmission:!1,hash:"e19068f7f6c92b5643a3f8fbf2f895e0",slug:"modelling-and-control-of-switched-reluctance-machines",bookSignature:"Rui Esteves Araújo and José Roberto Camacho",coverURL:"https://cdn.intechopen.com/books/images_new/8899.jpg",editedByType:"Edited by",editors:[{id:"31663",title:"Prof.",name:"Rui Esteves",middleName:"Esteves",surname:"Araújo",slug:"rui-esteves-araujo",fullName:"Rui Esteves Araújo"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10154",title:"Analysis of Electrical Machines",subtitle:null,isOpenForSubmission:!1,hash:"8263b7475172b952a9fa0a4de2ea4772",slug:"analysis-of-electrical-machines",bookSignature:"Valéria Hrabovcová, Pavol Rafajdus and Pavol Makyš",coverURL:"https://cdn.intechopen.com/books/images_new/10154.jpg",editedByType:"Authored by",editors:[{id:"313453",title:"Dr.",name:"Valeria",middleName:null,surname:"Hrabovcova",slug:"valeria-hrabovcova",fullName:"Valeria Hrabovcova"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"3",chapterContentType:"chapter",authoredCaption:"Authored by"}},{type:"book",id:"6604",title:"Optimization and Control of Electrical Machines",subtitle:null,isOpenForSubmission:!1,hash:"3165f6e04a714f478a45e847693a4cce",slug:"optimization-and-control-of-electrical-machines",bookSignature:"Abdel Ghani Aissaoui, Ahmed Tahour and Ilhami Colak",coverURL:"https://cdn.intechopen.com/books/images_new/6604.jpg",editedByType:"Edited by",editors:[{id:"105795",title:"Prof.",name:"Abdel Ghani",middleName:null,surname:"Aissaoui",slug:"abdel-ghani-aissaoui",fullName:"Abdel Ghani Aissaoui"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"4688",title:"Induction Motors",subtitle:"Applications, Control and Fault Diagnostics",isOpenForSubmission:!1,hash:"68a23d203b6d740e87ae48ecbe0e7b71",slug:"induction-motors-applications-control-and-fault-diagnostics",bookSignature:"Raul Igmar Gregor Recalde",coverURL:"https://cdn.intechopen.com/books/images_new/4688.jpg",editedByType:"Edited by",editors:[{id:"113744",title:"Dr.",name:"Raúl",middleName:"Igmar",surname:"Gregor",slug:"raul-gregor",fullName:"Raúl Gregor"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"3332",title:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies",subtitle:null,isOpenForSubmission:!1,hash:"6d337e7226358db0c8c7ca1b98c8c745",slug:"advances-in-micro-nano-electromechanical-systems-and-fabrication-technologies",bookSignature:"Kenichi Takahata",coverURL:"https://cdn.intechopen.com/books/images_new/3332.jpg",editedByType:"Edited by",editors:[{id:"4541",title:"Prof.",name:"Kenichi",middleName:null,surname:"Takahata",slug:"kenichi-takahata",fullName:"Kenichi Takahata"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"853",title:"Microelectromechanical Systems and Devices",subtitle:null,isOpenForSubmission:!1,hash:"a0594531ed8be220e64caf0a87470afa",slug:"microelectromechanical-systems-and-devices",bookSignature:"Nazmul Islam",coverURL:"https://cdn.intechopen.com/books/images_new/853.jpg",editedByType:"Edited by",editors:[{id:"23953",title:"Dr",name:"Nazmul",middleName:null,surname:"Islam",slug:"nazmul-islam",fullName:"Nazmul Islam"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}],booksByTopicTotal:6,mostCitedChapters:[{id:"33604",doi:"10.5772/29671",title:"Diamond, Diamond-Like Carbon (DLC) and Diamond-Like Nanocomposite (DLN) Thin Films for MEMS Applications",slug:"diamond-diamond-like-carbon-dlc-and-diamond-like-nanocomposite-dln-thin-films-for-mems-applications-",totalDownloads:7663,totalCrossrefCites:2,totalDimensionsCites:24,book:{slug:"microelectromechanical-systems-and-devices",title:"Microelectromechanical Systems and Devices",fullTitle:"Microelectromechanical Systems and Devices"},signatures:"T. S. Santra, T. K. Bhattacharyya, P. Patel, F. G. Tseng and T. K. Barik",authors:[{id:"78847",title:"Dr.",name:"Tarun",middleName:"Kumar",surname:"Barik",slug:"tarun-barik",fullName:"Tarun Barik"},{id:"78878",title:"Prof.",name:"Tarun",middleName:null,surname:"Bhattacharyya",slug:"tarun-bhattacharyya",fullName:"Tarun Bhattacharyya"},{id:"78881",title:"Dr.",name:"Tuhin",middleName:"Subhra",surname:"Santra",slug:"tuhin-santra",fullName:"Tuhin Santra"},{id:"78889",title:"Mr.",name:"Prateek",middleName:null,surname:"Patel",slug:"prateek-patel",fullName:"Prateek Patel"}]},{id:"44810",doi:"10.5772/55369",title:"Electroporation Based Drug Delivery and Its Applications",slug:"electroporation-based-drug-delivery-and-its-applications",totalDownloads:2845,totalCrossrefCites:2,totalDimensionsCites:9,book:{slug:"advances-in-micro-nano-electromechanical-systems-and-fabrication-technologies",title:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies",fullTitle:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies"},signatures:"Tuhin Subhra Santra, Pen-Cheng Wang and Fang Gang Tseng",authors:[{id:"78881",title:"Dr.",name:"Tuhin",middleName:"Subhra",surname:"Santra",slug:"tuhin-santra",fullName:"Tuhin Santra"},{id:"156839",title:"Prof.",name:"Fang",middleName:null,surname:"Tseng",slug:"fang-tseng",fullName:"Fang Tseng"}]},{id:"33595",doi:"10.5772/28251",title:"Dynamics of RF Micro-Mechanical Capacitive Shunt Switches in Coplanar Waveguide Configuration",slug:"dynamics-of-rf-micro-mechanical-capacitive-shunt-switches-in-coplanar-waveguide-configuration",totalDownloads:2575,totalCrossrefCites:3,totalDimensionsCites:6,book:{slug:"microelectromechanical-systems-and-devices",title:"Microelectromechanical Systems and Devices",fullTitle:"Microelectromechanical Systems and Devices"},signatures:"Romolo Marcelli, Daniele Comastri, Andrea Lucibello, Giorgio De Angelis, Emanuela Proietti and Giancarlo Bartolucci",authors:[{id:"73246",title:"Dr.",name:"Romolo",middleName:null,surname:"Marcelli",slug:"romolo-marcelli",fullName:"Romolo Marcelli"},{id:"73290",title:"Dr.",name:"Daniele",middleName:null,surname:"Comastri",slug:"daniele-comastri",fullName:"Daniele Comastri"},{id:"73292",title:"Dr.",name:"Andrea",middleName:null,surname:"Lucibello",slug:"andrea-lucibello",fullName:"Andrea Lucibello"},{id:"73294",title:"Dr.",name:"Giorgio",middleName:null,surname:"De Angelis",slug:"giorgio-de-angelis",fullName:"Giorgio De Angelis"},{id:"73295",title:"Dr.",name:"Emanuela",middleName:null,surname:"Proietti",slug:"emanuela-proietti",fullName:"Emanuela Proietti"},{id:"73296",title:"Prof.",name:"Giancarlo",middleName:null,surname:"Bartolucci",slug:"giancarlo-bartolucci",fullName:"Giancarlo Bartolucci"}]}],mostDownloadedChaptersLast30Days:[{id:"48819",title:"Induction Generator in Wind Power Systems",slug:"induction-generator-in-wind-power-systems",totalDownloads:3170,totalCrossrefCites:1,totalDimensionsCites:2,book:{slug:"induction-motors-applications-control-and-fault-diagnostics",title:"Induction Motors",fullTitle:"Induction Motors - Applications, Control and Fault Diagnostics"},signatures:"Yu Zou",authors:[{id:"174152",title:"Dr.",name:"Yu",middleName:null,surname:"Zou",slug:"yu-zou",fullName:"Yu Zou"}]},{id:"44825",title:"Nanolithography",slug:"nanolithography",totalDownloads:7656,totalCrossrefCites:0,totalDimensionsCites:2,book:{slug:"advances-in-micro-nano-electromechanical-systems-and-fabrication-technologies",title:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies",fullTitle:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies"},signatures:"Gunasekaran Venugopal and Sang-Jae Kim",authors:[{id:"81419",title:"Prof.",name:"Sang Jae",middleName:null,surname:"Kim",slug:"sang-jae-kim",fullName:"Sang Jae Kim"},{id:"91674",title:"Dr.",name:"Gunasekaran",middleName:null,surname:"Venugopal",slug:"gunasekaran-venugopal",fullName:"Gunasekaran Venugopal"}]},{id:"69801",title:"Modeling and Simulation of Switched Reluctance Machines",slug:"modeling-and-simulation-of-switched-reluctance-machines",totalDownloads:335,totalCrossrefCites:0,totalDimensionsCites:0,book:{slug:"modelling-and-control-of-switched-reluctance-machines",title:"Modelling and Control of Switched Reluctance Machines",fullTitle:"Modelling and Control of Switched Reluctance Machines"},signatures:"Mahmoud Hamouda and László Számel",authors:[{id:"293824",title:"Dr.",name:"Mahmoud",middleName:null,surname:"Hamouda",slug:"mahmoud-hamouda",fullName:"Mahmoud Hamouda"}]},{id:"49535",title:"Analysis and Methodology for Determining the Parasitic Capacitances in VSI-fed IM Drives Based on PWM Technique",slug:"analysis-and-methodology-for-determining-the-parasitic-capacitances-in-vsi-fed-im-drives-based-on-pw",totalDownloads:1721,totalCrossrefCites:0,totalDimensionsCites:0,book:{slug:"induction-motors-applications-control-and-fault-diagnostics",title:"Induction Motors",fullTitle:"Induction Motors - Applications, Control and Fault Diagnostics"},signatures:"Rudolf Ribeiro Riehl, Fernando de Souza Campos, Alceu Ferreira\nAlves and Ernesto Ruppert Filho",authors:[{id:"37044",title:"Prof.",name:"Ernesto",middleName:null,surname:"Ruppert",slug:"ernesto-ruppert",fullName:"Ernesto Ruppert"},{id:"39440",title:"Dr.",name:"Fernando",middleName:null,surname:"de Souza Campos",slug:"fernando-de-souza-campos",fullName:"Fernando de Souza Campos"},{id:"174758",title:"Prof.",name:"Rudolf",middleName:null,surname:"Riehl",slug:"rudolf-riehl",fullName:"Rudolf Riehl"},{id:"177415",title:"Prof.",name:"Alceu",middleName:null,surname:"Ferreira Alves",slug:"alceu-ferreira-alves",fullName:"Alceu Ferreira Alves"}]},{id:"33596",title:"Characterization and Modeling of Charging Effects in Dielectrics for the Actuation of RF MEMS Ohmic Series and Capacitive Shunt Switches",slug:"characterization-and-modeling-of-charging-effects-in-dielectrics-for-the-actuation-of-rf-mems-ohmic-",totalDownloads:1969,totalCrossrefCites:2,totalDimensionsCites:2,book:{slug:"microelectromechanical-systems-and-devices",title:"Microelectromechanical Systems and Devices",fullTitle:"Microelectromechanical Systems and Devices"},signatures:"Romolo Marcelli, Andrea Lucibello, Giorgio De Angelis, Emanuela Proietti, George Papaioannou, Giancarlo Bartolucci, Flavio Giacomozzi and Benno Margesin",authors:[{id:"73246",title:"Dr.",name:"Romolo",middleName:null,surname:"Marcelli",slug:"romolo-marcelli",fullName:"Romolo Marcelli"}]},{id:"33587",title:"Implantable Parylene MEMS RF Coil for Epiretinal Prostheses",slug:"implantable-parylene-mems-rf-coil-for-epiretinal-prostheses",totalDownloads:2926,totalCrossrefCites:0,totalDimensionsCites:1,book:{slug:"microelectromechanical-systems-and-devices",title:"Microelectromechanical Systems and Devices",fullTitle:"Microelectromechanical Systems and Devices"},signatures:"Wen Li, Damien C. Rodger, James D. Weiland, Mark S. Humayun, Wentai Liu and Yu-Chong Tai",authors:[{id:"76685",title:"Dr.",name:"Wen",middleName:null,surname:"Li",slug:"wen-li",fullName:"Wen Li"},{id:"76692",title:"Dr.",name:"Damien",middleName:"C.",surname:"Rodger",slug:"damien-rodger",fullName:"Damien Rodger"},{id:"76694",title:"Dr.",name:"James",middleName:null,surname:"Weiland",slug:"james-weiland",fullName:"James Weiland"},{id:"76695",title:"Dr.",name:"Mark",middleName:null,surname:"Humayun",slug:"mark-humayun",fullName:"Mark Humayun"},{id:"76696",title:"Dr.",name:"Yu-Chong",middleName:null,surname:"Tai",slug:"yu-chong-tai",fullName:"Yu-Chong Tai"}]},{id:"44815",title:"Liquid Encapsulation Technology for Microelectromechanical Systems",slug:"liquid-encapsulation-technology-for-microelectromechanical-systems",totalDownloads:2732,totalCrossrefCites:2,totalDimensionsCites:4,book:{slug:"advances-in-micro-nano-electromechanical-systems-and-fabrication-technologies",title:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies",fullTitle:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies"},signatures:"Norihisa Miki",authors:[{id:"159201",title:"Associate Prof.",name:"Norihisa",middleName:null,surname:"Miki",slug:"norihisa-miki",fullName:"Norihisa Miki"}]},{id:"44900",title:"Nanotechnology for Packaging",slug:"nanotechnology-for-packaging",totalDownloads:2236,totalCrossrefCites:0,totalDimensionsCites:0,book:{slug:"advances-in-micro-nano-electromechanical-systems-and-fabrication-technologies",title:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies",fullTitle:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies"},signatures:"Artin Petrossians, John J. Whalen III, James D. Weiland and Florian\nMansfeld",authors:[{id:"157566",title:"Dr.",name:"Artin",middleName:null,surname:"Petrossians",slug:"artin-petrossians",fullName:"Artin Petrossians"}]},{id:"44794",title:"CMOS Compatible Bulk Micromachining",slug:"cmos-compatible-bulk-micromachining",totalDownloads:2762,totalCrossrefCites:1,totalDimensionsCites:4,book:{slug:"advances-in-micro-nano-electromechanical-systems-and-fabrication-technologies",title:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies",fullTitle:"Advances in Micro/Nano Electromechanical Systems and Fabrication Technologies"},signatures:"John Ojur Dennis, Farooq Ahmad and M. Haris Khir",authors:[{id:"161158",title:"Associate Prof.",name:"John Ojur",middleName:null,surname:"Dennis",slug:"john-ojur-dennis",fullName:"John Ojur Dennis"},{id:"167986",title:"Dr.",name:"Farooq",middleName:null,surname:"Ahmad",slug:"farooq-ahmad",fullName:"Farooq Ahmad"}]},{id:"33598",title:"Optical MEMS",slug:"optical-mems",totalDownloads:8188,totalCrossrefCites:0,totalDimensionsCites:1,book:{slug:"microelectromechanical-systems-and-devices",title:"Microelectromechanical Systems and Devices",fullTitle:"Microelectromechanical Systems and Devices"},signatures:"Wibool Piyawattanametha and Zhen Qiu",authors:[{id:"70846",title:"Dr.",name:"Wibool",middleName:null,surname:"Piyawattanametha",slug:"wibool-piyawattanametha",fullName:"Wibool Piyawattanametha"}]}],onlineFirstChaptersFilter:{topicSlug:"electromechanics",limit:3,offset:0},onlineFirstChaptersCollection:[],onlineFirstChaptersTotal:0},preDownload:{success:null,errors:{}},aboutIntechopen:{},privacyPolicy:{},peerReviewing:{},howOpenAccessPublishingWithIntechopenWorks:{},sponsorshipBooks:{sponsorshipBooks:[{type:"book",id:"10176",title:"Microgrids and Local Energy Systems",subtitle:null,isOpenForSubmission:!0,hash:"c32b4a5351a88f263074b0d0ca813a9c",slug:null,bookSignature:"Prof. Nick Jenkins",coverURL:"https://cdn.intechopen.com/books/images_new/10176.jpg",editedByType:null,editors:[{id:"55219",title:"Prof.",name:"Nick",middleName:null,surname:"Jenkins",slug:"nick-jenkins",fullName:"Nick Jenkins"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}}],offset:8,limit:8,total:1},route:{name:"chapter.detail",path:"/books/phytochemicals-in-human-health/analytical-methods-of-isolation-and-identification",hash:"",query:{},params:{book:"phytochemicals-in-human-health",chapter:"analytical-methods-of-isolation-and-identification"},fullPath:"/books/phytochemicals-in-human-health/analytical-methods-of-isolation-and-identification",meta:{},from:{name:null,path:"/",hash:"",query:{},params:{},fullPath:"/",meta:{}}}},function(){var e;(e=document.currentScript||document.scripts[document.scripts.length-1]).parentNode.removeChild(e)}()