Chemical composition of the ACC-steel and AIR steel (wt.%).
\r\n\t
",isbn:"978-1-83969-347-2",printIsbn:"978-1-83969-346-5",pdfIsbn:"978-1-83969-348-9",doi:null,price:0,priceEur:0,priceUsd:0,slug:null,numberOfPages:0,isOpenForSubmission:!0,hash:"4fc73beb0e4416a20cc70c8163fe436f",bookSignature:"Dr. Pinar Erkekoglu",publishedDate:null,coverURL:"https://cdn.intechopen.com/books/images_new/9836.jpg",keywords:"KRAS Gene, Oncogene, Tumor Suppressor Gene, Mutation, Cancer, Microtubule-Associated Protein (MAP), GTPase, Pathological Conditions, Epidermal Nevus, Noonan Syndrome, Costello Syndrome, Environmental Chemicals",numberOfDownloads:null,numberOfWosCitations:0,numberOfCrossrefCitations:null,numberOfDimensionsCitations:null,numberOfTotalCitations:null,isAvailableForWebshopOrdering:!0,dateEndFirstStepPublish:"November 17th 2020",dateEndSecondStepPublish:"December 15th 2020",dateEndThirdStepPublish:"February 13th 2021",dateEndFourthStepPublish:"May 4th 2021",dateEndFifthStepPublish:"July 3rd 2021",remainingDaysToSecondStep:"a month",secondStepPassed:!0,currentStepOfPublishingProcess:3,editedByType:null,kuFlag:!1,biosketch:"A pioneering researcher in toxicology, vaccinology, cosmetics, and Board Member of Turkish Pharmacists Association Pharmacy Academia and Board Member of Hacettepe Vaccine Institute. Published more than 150 scientific papers in international/national journals. Associate editor of the Turkish Journal of Pharmaceutical Sciences.",coeditorOneBiosketch:null,coeditorTwoBiosketch:null,coeditorThreeBiosketch:null,coeditorFourBiosketch:null,coeditorFiveBiosketch:null,editors:[{id:"109978",title:"Prof.",name:"Pinar",middleName:null,surname:"Erkekoglu",slug:"pinar-erkekoglu",fullName:"Pinar Erkekoglu",profilePictureURL:"https://mts.intechopen.com/storage/users/109978/images/system/109978.JPG",biography:"Pınar Erkekoglu was born in Ankara, Turkey. She graduated with a BS from Hacettepe University Faculty of Pharmacy. Later, she received an MSci and Ph.D. in Toxicology. She completed a part of her Ph.D. studies in Grenoble, France, at Universite Joseph Fourier and CEA/INAC/LAN after receiving a full scholarship from both the Erasmus Scholarship Program and CEA. She worked as a post-doc and a visiting associate in the Biological Engineering Department at Massachusetts Institute of Technology. She is currently working as a full professor at Hacettepe University, Faculty of Pharmacy, Department of Pharmaceutical Toxicology. Her main study interests are clinical and medical aspects of toxicology, endocrine-disrupting chemicals, and oxidative stress. She has published more than 150 papers in national and international journals. Dr. Erkekoglu has been a European Registered Toxicologist (ERT) since 2014.",institutionString:"Hacettepe University",position:null,outsideEditionCount:0,totalCites:0,totalAuthoredChapters:"4",totalChapterViews:"0",totalEditedBooks:"4",institution:{name:"Hacettepe University",institutionURL:null,country:{name:"Turkey"}}}],coeditorOne:null,coeditorTwo:null,coeditorThree:null,coeditorFour:null,coeditorFive:null,topics:[{id:"6",title:"Biochemistry, Genetics and Molecular Biology",slug:"biochemistry-genetics-and-molecular-biology"}],chapters:null,productType:{id:"1",title:"Edited Volume",chapterContentType:"chapter",authoredCaption:"Edited by"},personalPublishingAssistant:{id:"301331",firstName:"Mia",lastName:"Vulovic",middleName:null,title:"Mrs.",imageUrl:"https://mts.intechopen.com/storage/users/301331/images/8498_n.jpg",email:"mia.v@intechopen.com",biography:"As an Author Service Manager, my responsibilities include monitoring and facilitating all publishing activities for authors and editors. From chapter submission and review to approval and revision, copyediting and design, until final publication, I work closely with authors and editors to ensure a simple and easy publishing process. I maintain constant and effective communication with authors, editors and reviewers, which allows for a level of personal support that enables contributors to fully commit and concentrate on the chapters they are writing, editing, or reviewing. I assist authors in the preparation of their full chapter submissions and track important deadlines and ensure they are met. I help to coordinate internal processes such as linguistic review, and monitor the technical aspects of the process. As an ASM I am also involved in the acquisition of editors. Whether that be identifying an exceptional author and proposing an editorship collaboration, or contacting researchers who would like the opportunity to work with IntechOpen, I establish and help manage author and editor acquisition and contact."}},relatedBooks:[{type:"book",id:"5176",title:"Nutritional Deficiency",subtitle:null,isOpenForSubmission:!1,hash:"a2e20dabc8ed6fbaef3686be8c6fce99",slug:"nutritional-deficiency",bookSignature:"Pınar Erkekoglu and Belma Kocer-Gumusel",coverURL:"https://cdn.intechopen.com/books/images_new/5176.jpg",editedByType:"Edited by",editors:[{id:"109978",title:"Prof.",name:"Pinar",surname:"Erkekoglu",slug:"pinar-erkekoglu",fullName:"Pinar Erkekoglu"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"5836",title:"Bisphenol A",subtitle:"Exposure and Health Risks",isOpenForSubmission:!1,hash:"446599b9e5cf929537d445edc546c449",slug:"bisphenol-a-exposure-and-health-risks",bookSignature:"Pinar Erkekoglu and Belma Kocer-Gumusel",coverURL:"https://cdn.intechopen.com/books/images_new/5836.jpg",editedByType:"Edited by",editors:[{id:"109978",title:"Prof.",name:"Pinar",surname:"Erkekoglu",slug:"pinar-erkekoglu",fullName:"Pinar Erkekoglu"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"7281",title:"Oncogenes and Carcinogenesis",subtitle:null,isOpenForSubmission:!1,hash:"728df4ace35f652725e5b94da45d0c4d",slug:"oncogenes-and-carcinogenesis",bookSignature:"Pinar Erkekoglu",coverURL:"https://cdn.intechopen.com/books/images_new/7281.jpg",editedByType:"Edited by",editors:[{id:"109978",title:"Prof.",name:"Pinar",surname:"Erkekoglu",slug:"pinar-erkekoglu",fullName:"Pinar Erkekoglu"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"6486",title:"Glutathione in Health and Disease",subtitle:null,isOpenForSubmission:!1,hash:"23fb1f2e0cea5cf004d57bc8c0d46ce4",slug:"glutathione-in-health-and-disease",bookSignature:"Pinar Erkekoglu and Belma Kocer-Gumusel",coverURL:"https://cdn.intechopen.com/books/images_new/6486.jpg",editedByType:"Edited by",editors:[{id:"109978",title:"Prof.",name:"Pinar",surname:"Erkekoglu",slug:"pinar-erkekoglu",fullName:"Pinar Erkekoglu"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"6694",title:"New Trends in Ion Exchange Studies",subtitle:null,isOpenForSubmission:!1,hash:"3de8c8b090fd8faa7c11ec5b387c486a",slug:"new-trends-in-ion-exchange-studies",bookSignature:"Selcan Karakuş",coverURL:"https://cdn.intechopen.com/books/images_new/6694.jpg",editedByType:"Edited by",editors:[{id:"206110",title:"Dr.",name:"Selcan",surname:"Karakuş",slug:"selcan-karakus",fullName:"Selcan Karakuş"}],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"}],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"}],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"}],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"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"1373",title:"Ionic Liquids",subtitle:"Applications and Perspectives",isOpenForSubmission:!1,hash:"5e9ae5ae9167cde4b344e499a792c41c",slug:"ionic-liquids-applications-and-perspectives",bookSignature:"Alexander Kokorin",coverURL:"https://cdn.intechopen.com/books/images_new/1373.jpg",editedByType:"Edited by",editors:[{id:"19816",title:"Prof.",name:"Alexander",surname:"Kokorin",slug:"alexander-kokorin",fullName:"Alexander Kokorin"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}]},chapter:{item:{type:"chapter",id:"69094",title:"Effect of Textures and Microstructures on the Occurrence of Delamination during and after Fracture Toughness Tests of API X80 Steel Plates",doi:"10.5772/intechopen.88001",slug:"effect-of-textures-and-microstructures-on-the-occurrence-of-delamination-during-and-after-fracture-t",body:'\nThe efficiency of pipeline transport systems, widely employed in the oil and gas industries, depends, to a significant extent, on increasing diameters and working pressures while reducing the wall thickness to lower the cost per transport unit [1, 2]. In this context, pipeline steels have been continuously developed toward increased strength, toughness, and formability, as well as maintaining low carbon composition to ensure adequate weldability [1, 2]. In order to achieve these goals, pipeline steels, such as API 5 L X80, X100, and X120, rely upon alloy design and Thermo-Mechanically Controlled Processing (TMCP) to produce grain refinement by controlled deformation of austenite during rolling [3, 4]. In general, rolling of TMCP steel plates are carried out in two stages: first, rough rolling is performed in the temperature range of austenite recrystallization while alloying elements are in solution (normally above 1100°C); then, at lower temperatures (typically below 1000°C, sometimes in the intercritical range) finish rolling passes are executed, cold-working the matrix [4–6]. At these lower temperatures, the presence of precipitated carbides inhibit grain growth, and fine austenite grains, substructure, and dislocations assist the formation of a refined ferritic or bainitic structure, depending on the cooling conditions [4, 7]. Because of the low-temperature rolling, diffusional phenomena are limited, and the deformed microstructure carries strong crystallographic textures, which lead to anisotropy and possibly a decrease of mechanical properties [4, 5, 8]. As such, numerous investigations have been performed recently to understand texture formation in TMCP steels and its correlation with mechanical properties, especially impact toughness behavior (Charpy tests) [5, 6, 8–10].
\nFracture toughness and how crack propagation occurs in steels, depend on their chemical composition [4, 5, 11–13], resultant microstructures [4, 5, 10–12, 14], inclusions [4, 5, 11, 12], grain morphology, e.g., pancaked or elongated [4, 12], crystallographic textures [4, 5, 10–14] and residual stresses produced after the TMCP process [15]. Moreover, many studies in the literature point out the crystallographic orientation as the major cause of delamination, i.e., the presence of 001 plane more specifically [5, 8, 11, 15–18]. Most of the literature presents impact toughness results from Charpy tests. Charpy tests are recommended for qualitative estimation of toughness, with samples that can be machined with low-cost, tests are conducted rapidly, and results are easily processed [19]. For accurate measurements of toughness, crack-tip opening displacement (CTOD) tests are recommended [20]. Also, the crack-tip constraint of Charpy samples changes due to the dynamic loading [21], however, a pipeline under operative conditions do not suffer impact loads, but rather a quasi-static evolution of pressure and internal forces. CTOD tests, with samples designed to guarantee a constant crack-tip triaxiality [21], which represents a crack propagation on opening mode I in quasi-static conditions, has not been well documented in the literature related to the fracture toughness measurement of pipelines.
\nDelamination is a brittle fracture behavior reported in TMCP steels [9, 17, 22–25], which occurs at the weakest interface, usually near the crack tip. There are two types of delamination based on its geometry: (i) crack divider and (ii) crack arrester. The divider branches the crack into a series of cracks traveling a narrower path [22, 23]. The arrester delamination does not result in crack branching, maintaining the same width of propagation. However, it reallocates the crack at a region with no plastic zone ahead of the crack, triggering the re-initiation of the crack under conditions of nearly uniaxial tension, resulting in high absorption of energy [22, 23]. There are several reports of delaminations of both types in Charpy tests in the literature [9, 17, 23–25] and few reports of delaminations during CTOD tests in the literature [8].
\nZong et al. studied the influence of crystallographic orientation upon impact toughness through Charpy impact tests on an API X100 steel [17]. The influence of microstructure on the toughness results was excluded by using the same steel plate. The influence of crystallography orientation was assessed by milling out samples from the different orientation, 0, 30, 45, 60 and 90° tilted from rolling direction. The best condition was found at 0° and then at 90° [17], where the fracture orientation factor, a factor used to characterize the anisotropy of the fracture strength based on <100>, presented lower values compared to 45° to RD, the direction in which maximum fracture orientation factor was obtained. Bakshi et al. [5] studied the influence of the TMCP, microstructure and crystallography on an X70 also varying the orientation of the machined samples for Charpy impact tests. As many cited works, Bakshi et al. [5] also reported that the presence of 001 plane induces delamination.
\nPyshmintsev et al. [26] suggested that the clustering of (001) cleavage plane parallel to the crack plane does not lead to delamination and splitting phenomena, but that microstructure plays the major role. It was reported that prior austenite grain boundary with cube rotation texture lying parallel to crack plane propagation causes severe splitting [26]. Another study [27], reported that the anisotropy in Charpy tests results could be correlated to factors as the spatial grain distribution, grain shape, and the distribution of the phases and microconstituents, mainly the hardening ones. Kimura et al. reported that grain size was the main key to control yield strength and delamination. By applying a TMCP, ultra-fined grain was obtained, increasing the yield strength and triggering delaminations of crack-arrest type, increasing toughness as well [23].
\nIn this work, we aim to determine the causes of the occurrence of delamination occurring during and after fracture toughness tests. The present investigation was conducted using crystallographic textures, microstructures analysis by light optical microscopy (LOM), scanning electron microscopy (SEM) coupled with energy-dispersive x-ray spectroscopy (EDS), electron back-scattered diffraction (EBSD), X-ray diffraction (XRD), and mechanical assessment with tensile tests and fracture toughness test, specifically crack-tip opening displacement (CTOD) tests, in two steel plates of X80 fabricated by TMCP. In addition, a complete fractographic analysis was conducted. The first steel was air-cooled after the last rolling pass in the intercritical region, referred in the text as the AIR-steel. It presented a banded microstructure and segregation in the mid-thickness of the plate, with elongated manganese sulfide particles and pearlite colonies. The second steel, hereafter designated as ACC-steel, underwent accelerated-cooling after finish rolling and exhibited a bainitic matrix with equiaxed bainite packages.
\nTwo plates of X80 grade TMCP steels, produced elsewhere using different cooling conditions, air-cooling (AIR-steel) and accelerated-cooling (ACC-steel) after finish rolling in the intercritical range, were used in the present study. The chemical composition of both steel plates is shown in Table 1, which is in good agreement with the ISO 3183 standard [28] requirements.
\nSteel | \nC | \nMn | \nV | \nNb | \nTi | \nSi | \nMo | \nNi | \nP* | \nS* | \n
---|---|---|---|---|---|---|---|---|---|---|
ISO 3183 standard [28] | \n0.18 | \n1.9 | \n* | \n* | \n* | \n0.45 | \n0.5 | \n1 | \n250 | \n150 | \n
ACC-steel | \n0.05 | \n1.73 | \n0.01 | \n0.04 | \n0.01 | \n0.26 | \n0.18 | \n0.25 | \n90 | \n4 | \n
AIR-steel | \n0.08 | \n2.07 | \n0.04 | \n0.07 | \n0.01 | \n0.22 | \n0.18 | \n0.01 | \n50 | \n22 | \n
Chemical composition of the ACC-steel and AIR steel (wt.%).
ISO 3183 standard [28] was used for comparisons purpose (*ppm).
The fracture toughness assessment was conducted using CTOD tests, with experimental testing according to the ASTM 1820-13 standard [29]. Rectangular (Bx2B) single edge bending notched samples with different thicknesses (B) of 7 and 15 mm were assessed. First, the 7-mm-thick samples were tested at 25°C to analyze the effect of the crack propagation direction in fracture toughness; therefore notches were located through the transverse (L-T) and longitudinal (T-L) direction (more details about crack orientation the ASTM E1823 standard [30]). After that, the direction of best fracture toughness result of the 7-mm-thick samples in each steel was chosen to conduct tests in thicker plates (15 mm), to increase the constraint of the crack-tip and assess the effect of temperature. 15-mm-thick samples were assessed at 0, −20 and −40°C, using the L-T direction in the AIR-steel and T-L direction in the ACC-steel. Notice that ACC-steel CTOD results were previously reported by Avila et al. [31]. Side grooves were machined on 15-mm-thick samples after pre-cracking to increase triaxiality state at the crack-tip, with straight crack-tip fronts during the CTOD tests.
\nTensile tests were conducted in cylindrical samples with a diameter of 6 mm in the reduced area, following ASTM E8 standard [32]. Tensile samples were machined in rolling and transverse directions. The tensile tests were also conducted at temperatures 25, 0, −20 and −40°C.
\nX-ray Diffraction (XRD) was conducted to assess crystallographic texture along the normal and transverse directions (ND-TD). CuKα radiation with wavelength λ = 1.54059 Å, a continuous scanning speed of 0.14°/min, 0.02° per step and 2θ range of 40 to 100° were used during the X-ray measuring. Experimental pole figures were determined by varying azimuthal angle phi (ϕ) 0 to 360° in 3° steps and tilting angle chi (χ) from 0 to 87° in 3° steps. Orientation distribution functions (ODFs) were obtained from independent measurements of the (110), (200) and (211) planes.
\nFor metallographic purposes, samples were ground from 100-grit up to 1200-grit SiC paper. Polishing was performed with diamond pastes of 3 and 1 μm and final polishing was performed in a silica suspension with 0.06 μm particle size.
\nMicrostructural characterization was carried out on all three planes: rolling, transverse, and normal, where the rolling plane is perpendicular to the rolling direction (RD), likewise the transverse plane to TD and normal plane to ND. LOM, SEM coupled with an EDS and EBSD detectors, and Vickers hardness measurements were performed. The EBSD measurements were conducted on non-etched samples and two different magnifications were used. Areas of 1500x1300 μm2 with a step size of 2.5 μm and 75 × 65 μm2 with step sizes of 0.1 μm were used. Misorientation above 15° was used to considered grain boundaries. Then the effective grain size was determined using the area method. Grain size measured by the linear intercept technique, was carried out on LOM images. Samples were etched with 2% Nital.
\n\nFigure 1a–c shows the microstructure of both steel plates. Microstructural misorientation cubes in Figure 1d, e present the microstructure morphology and distribution near the mid-thickness. The fine secondary phases and constituents (SP) presence between ferrite grains in steels depends on the alloying elements and their effect on the transformation kinetics during cooling [33]. The air-cooling after the finishing rolling pass provides enough time at elevated temperature, enabling diffusion and resulting in a variety of incomplete transformations and microconstituents classified into martensite-austenite (M-A), degenerated pearlite (DP), bainite and martensite [33–35]. The AIR-steel exhibited, in Figure 1a, b, a banded microstructure composed by polygonal ferrite, some quasi-polygonal ferrite, pancake grains evidencing a finishing rolling pass at an intercritical temperature, with the formation of banding of fine phases and constituents. A macrosegregation band in the mid-plane induced by solidification is visible on the transverse plane.
\nSEM micrographs of the rolling plane of the plates: (a, b) AIR-steel presenting segregation and secondary phases (SP), (c) ACC-steel showing a homogeneous microstructure. Misorientation angle distribution cubes of (d) AIR-steel and (e) ACC-steel. Grain boundary misorientation >10°.
The ACC-steel presented a homogenous microstructure, as shown in Figure 1c, d, over the transverse and rolling planes composed by granular bainite, with more equiaxed shape, some elongated grains, and SP. Grain size measurements using EBSD data and conventional optical procedure showed similar values, around 1.2 μm, as shown in Table 2. However, based on the standard deviation, the grain sizes can be considered similar in both steel plates.
\nSteel | \nEBSD | \nOptical measurements | \n
---|---|---|
AIR | \n1.2 ± 0.05 | \n1.0 ± 0.03 | \n
ACC | \n1.4 ± 0.05 | \n1.2 ± 0.03 | \n
Grain size values of the studied steels.
Measurements in μm.
The ACC-steel presented a chemical composition with lower alloying elements content than AIR-steel, resulting in less MA and microconstituents dispersed on a bainitic matrix. The ACC-steel depicted a fine ferrite and bainite matrix with dispersed SP. In addition, the accelerated-cooling suppressed diffusion and favored the formation of bainite products, as packets of bainite and granular bainite [33, 36]. According to Bhadeshia et al. [37], bainite formation takes place first by the growth of one single crystal and formation of clusters, known as packet sheaves, by the cooperative growth of other crystals, with low misorientation angles between the sub-units. As ACC steel had a bainitic microstructure, it presented a higher content of low angle misorientation, between 5 and 15°, than the AIR-steel. The ACC steel presented similar morphology on both planes, rolling and transverse, as shown in Figure 1e since the accelerated-cooling resulted in a larger ferrite//bainite nucleation rate. Furthermore, the microstructure did not present elongated ferrite, evidencing a finishing rolling pass at a full austenitization temperature.
\nSP were observed in both plates of steel distributed around the ferritic matrix, as shown in Figure 2a, b. However, the AIR-steel presented a higher number of constituents within the light contrast bands, such as SP bands depicted in Figure 2a and zoomed-in in Figure 2b. The SP was composed of elongated and massive shapes of DP and M-A, and manganese sulfide (MnS), as detailed in Figure 3.
\nSEM micrographs of (a)–(c) AIR-steel and (d)–(f) ACC-steel.
EDS analysis of MnS elongated particles in the AIR-steel.
EDS analysis conducted at the mid-thickness on a specific region confirms the presence of MnS in the AIR-steel. These elongated MnS particles also depict silicon and titanium presence, as shown in Figure 4. ACC-steel did not show segregation in the mid-thickness.
\nThrough-thickness hardness profiles in the rolling and transverse planes of the steel of ACC-steel and AIR-steel.
The average hardness of the steel plates in the through-thickness direction was 238 ± 4 HV for the ACC-steel and 220 ± 4 HV for AIR-steel. There was no significant difference in hardness between rolling and transverse planes of each plate of steel considered separately, as shown in the hardness profiles presented in Figure 4.
\nODFs were constructed from the XRD and EBSD data and plotted in colored intensities diagrams using Bunge notation in Euler space, as depicted in Figure 5. The crystallographic representation for rolled steels is composed of a plane {hkl} which lies parallel to the normal plane and a direction <uvw>, which is parallel to the rolling direction [38] as schematically shown in Figure 5e. The reference system is based on RD, TD and ND, where their related planes are rolling, transversal and normal planes which lies perpendicular to their respective directions. The development of texture produced during hot-rolling at full austenitic region causes strong alpha-fiber development, which consists of {001} <110> to {110} <110> in ϕ2 = 45°, ϕ1 = 0°, ϕ = 0–90° [38]. It is a rotation on the {110} direction axis, being a fiber parallel to RD. As temperature decreases and cold-work increases, there is an increase of gamma-fiber, which consists of {111} <110> to {111} <112> in ϕ2 = 45°, ϕ1 = 0–90°, ϕ = 55° [38]. It is a rotation around the {111} plane, i.e., around the perpendicular direction of the plane, which is [111], being a parallel fiber to ND. In Figure 5a–d are retrieved the ODFs colored intensities, showing the presence of alpha-fiber and gamma-fiber. Both steels presented low gamma-fiber intensity compared to alpha-fiber. Comparing crystallographic textures in both steels, AIR-steel presented higher alpha-fiber and higher crystallographic intensity in XRD and EBSD measurements than ACC-steel as depicted in Figure 5a–f. Another component that plays an important role is the cube side lattice {100} since it is the cleavage plane on body-centered cubic (BCC) steels. The family plane {100} is likely to have a relationship to the occurrence of delaminations, as is described further in the present work.
\nODF plots at ϕ2 = 45° highlighting alpha-fiber presence, location and high intensity of (001)[110]: (a, b) XRD ODF analysis: (a) ACC-steel, (b) AIR-steel; (c, d) EBSD ODF analysis: (c) ACC-steel, (d) AIR-steel;(e) ODF map [39], (f) quantification of alpha-fiber intensity by XRD, showing higher values for AIR-steel, and (g) schematic representation of crystallographic (001) planes perpendicular to ND and [110] direction parallel to RD.
The crystallographic orientation distribution from EBSD analyses was performed to compare and validate that of XRD. The EBSD analyses were carried on rolling plane of both investigated samples out at areas of 1500 × 1300 μm2 with a step size of 2.5 μm containing about 1500 grains. Their related ODFs were calculated using the statistical method of kernel density estimation and presented in Figure 5. The results obtained by EBSD are similar to previous ODF results calculated by XRD. A certain difference between these methods could be attributed with a high statistical symmetry at each pole figure (XRD) and local grain orientation (EBSD). Overall texture intensity of AIR-steel was higher rather than ACC-steel due to the formation of {110}//RD grains accompanied by banded microstructure. Suikkanen et al. [40] characterized a {110} plane of the carbide-free bainitic ferrite similar to the martensitic transformation originated from close-packed {111} austenite plane because of the accommodation of transformation strains, enhancing the bainitic transformation. The formation of (211)[011] component could be explained by Shackleton and Kelly works which reported that the habit plane of cementite in lower bainitic ferrite is corresponding to \n
In order to investigate the role of local crystal orientations and boundary types, detailed EBSD measurements were carried out in rolling transversal planes of both AIR and ACC steels. Orientation image (OI) map, Kernel average misorientation (KAM) map, grain boundary (GB) map, Taylor factor (TF) maps, and normal direction pole figure (IPF) maps of each measurement were presented in Figure 6 for AIR-steel and Figure 7 for ACC-steel.
\n(a) OI map, (b) KAM map, (c) GB map, (d) TF maps, and (e) normal direction IPF maps of the rolling plane of AIR-steel.
(a) OI map, (b) KAM map, (c) GB map, (d) TF maps, and (e) normal direction IPF maps of the rolling plane of ACC-steel.
The orientation data collected with EBSD displayed by OIM or Euler colored maps, provides a basic presentation of the measured orientation. Grain boundaries are considered as crystal lattice defects, which can be identified by the point-to-point misorientation between neighboring data points, Figures 6a and 7a. Grain boundary energy is attributed by the interfacial region geometry between two adjacent crystals with different orientations. For example, the high angle boundaries (HABs), greater than 15°, are determined by point-to-point misorientation analysis [42, 43]. Low angle boundaries (LABs) and dislocation tangles were characterized from their misorientation angle (5–15° and 2–5°, respectively), Figures 6c and 7c. Also, coincident site lattice (CSL) boundaries with HABs with low stored energy due to good atomic fit between neighboring crystals can act as crack arrester.
\nKAM map indicates the local plastic strain variations measured between the central point and its nearest neighbors when the misorientation between them exceeds 5° in eliminating the effect of grain boundaries [44, 45]. The high KAM angles appear cumulative build-up of misorientation inside the grain or the presence of sub-grain boundaries, Figures 6b and 7b.
\nPencil glide occurs on {110}, {112}, {123} slip planes along the slip direction <111>, in BCC materials such as steel. The external stress imposes during deformation leads to activate the potential activated slip systems for each grain individually according to the crystal rotation axis method based on their Schmid factors [46–48]. Polycrystalline deformation is determined through all possible combinations of the potential slip systems compared with the imposed macroscopic stress state. Then, the yield response of individual grain is predicted based on favorably and unfavorably oriented for easier slip activation according to the geometrical lattice rotation axes. For instance, soft grains with low Taylor factor value (in blue color) have the least resistance to slip, while red-colored grains represent hard grains with highest Taylor factor, i.e., highest resistance to slip [46, 47], Figures 6d and 7d. Also, the corresponding rolling direction IPF obtained from each EBSD data is shown in Figures 6e and 7e, which can quantify the volume fraction of the crystallographic orientation of the grains.
\nElongation measured at tensile tests superior to 10% and yield strength above 400 MPa for all the evaluated conditions were found. Yield strength (YS) and ultimate tensile strength (UTS) are summarized in Figure 8, according to the tested temperature. As shown in Figure 8a and considering the results at room temperature, the ACC-steel fulfills the API standard requirement for the minimum yield strength (555 MPa) [28], in the rolling and transverse planes, to be classified as X80. The AIR-steel reaches the X80 grade specification requirement in the transverse plane, but not in the rolling plane, in which it reaches only the X70 specification requirement. Considering the ultimate tensile strength at room temperature (25°C), as shown in Figure 8b, both plates of steel fit into the X80 grade requirement.
\nSummary of the tensile tests results of the AIR-steel and ACC-steel: (a) yield strength (YS) and (b) ultimate strength (UTS). Tests were conducted in the transverse and parallel directions relative to the rolling direction.
Regarding the results presented in Figure 8, it is possible to state that anisotropy was found in both plates of steel, being more intense in the AIR-steel than in the ACC-steel, which presented a smaller difference in tensile results between the rolling and transverse planes. In addition, the AIR-steel tensile test results varied considerably between temperatures due to the heterogeneity of the microstructure.
\nAIR-steel fails the API X80 criterion for yield stress. The ACC-steel plates were machined from a pipe, a finished product, while AIR-steel plates came directly from TMCP plate production. For AIR-steel, a further U-O-E process would be necessary to transform plates into tubes, which would promote enough work-hardening to reach the yield stress of X80-grade specification [24]. Also, the YS/UTS ratio was not the predominant factor affecting the fracture toughness, where usually high YS/UTS ratios lead to low toughness, however, in this study high YS/UTS lead to high toughness.
\nFracture toughness results, measured by the CTOD parameter in mm, are summarized in Figure 9. For 7-mm-thick samples, AIR-steel presented lower average CTOD than ACC-steel, as shown in Figure 9a. AIR-steel presented difference of CTOD value between L-T and T-L geometries: L-T presented higher values than T-L. ACC-steel presented statistically equal results for both L-T and T-L. Therefore, ACC-steel presented higher toughness and less crystallographic texture effect than AIR-steel.
\nFracture toughness using CTOD parameter for ACC-steel and AIR-steel: (a) 7-mm-thick samples tested at 25°C; (b) 15-mm-thick samples tested at 0, −20 and −40°C. The L-T and T-L correspond to the ASTM E1823 [30] notches nomenclature. Tests were performed in the L-T and T-L direction in SE(B) samples. Results from ACC-steel with 15-mm-thick were published at [31].
For 15-mm-thick samples, both steels presented a CTOD decreasing trend lowering temperatures, as depicted in Figure 9b. The ACC-steel depicted a better toughness behavior at 0 and −20°C than AIR-steel; however, at −40°C, both steels showed similar CTOD. CTOD results obtained at 0°C were similar to those from 7-mm-thick samples at 25°C. Below 0°C, the drop in temperature caused a partial shift of biaxial tension state towards triaxial tension state, increasing the triaxiality state at the crack-tip and reducing the material ductility [23].
\nTo analyze the fracture surfaces, samples were submerged in liquid nitrogen and then broken by impact to separate samples into two halves. Thus, fracture surfaces of 7-mm-thick samples in Figure 10 and 15-mm-thick samples in Figure 11 can be observed. Fatigue pre-cracking region, crack propagation region during the CTOD test and final fracture caused by impact are also shown. The crack opening displacement (COD) and the applied force figure has been added to show the behavior of the material during the CTOD test.
\nFractured surfaces of the toughness of 7-mm thick samples tested at room temperature. AIR-steel: (a) L-T geometry, plastic behavior and occurrence of delamination during sample break; (b) T-L geometry, plastic behavior on CTOD zone and flat and brittle like behavior during sample break; (c) T-L geometry, occurrence of delamination during sample break; (d) force vs. COD experimental graph during CTOD test of the sample shown in (c), displaying red line at maximum achieved force. ACC-steel: (e) L-T geometry, plastic behavior and occurrence of delamination during sample break; (f) T-L geometry, plastic behavior on CTOD zone and flat and brittle like behavior during sample break; (g) T-L geometry, plastic behavior during CTOD and final fracture, with occurrence of delamination during sample break; (h) force vs. COD experimental graph during CTOD test of the sample shown in (g), displaying red line at maximum achieved force. COD: crack open displacement at the crack mouth.
Fractured surface of API X80 15-mm thick samples tested at different temperatures. AIR-steel in L-T geometry: (a) 0°C, plastic behavior only in CTOD zone, and no occurrence of delamination during CTOD; (b) −20°C, low plastic behavior in CTOD zone and next to delaminations. Delaminations occurred during CTOD test, causing pop-in; (c) brittle behavior with the occurrence of delamination during CTOD test; (d) force vs. COD experimental graph during CTOD test of the sample shown in (c), displaying early delaminations but not significant to end the test, and a red line at maximum achieved force. ACC-steel in T-L geometry: (e) 0°C, plastic behavior in CTOD zone; (f) low plastic behavior in CTOD zone and occurrence of delamination during CTOD test; (g) −40°C, brittle behavior during CTOD and final fracture, with occurrence of delamination during CTOD; (h) force vs. COD experimental graph during CTOD test of the sample shown in (g), displaying red line at occurred delamination, ending the test.
For 15-mm thick samples, the AIR-steel and ACC-steel specimens were tested in L-T and T-L geometries, respectively, due to the best CTOD results of 7-mm thick samples. For AIR-steel CTOD samples, all cases tested at −20 and −40°C presented delamination during CTOD test, totalizing 6 cases. Samples tested at 0°C presented no delamination occurrence. Most of the occurred delaminations manifested as pop-ins in the CTOD test curves and four cases the delamination were considered significant according to the ASTM 1820 standard [29], two at −20°C and the other two at −40°C, out of a total of 6 cases of delaminations. Notice that a pop-in event does not mean the start of brittle crack propagation, it is just a disparity of the stable crack propagation and is recommended to calculate CTOD values when they appear; however, the crack propagation continues stably until the end of the test.
\nMoreover, when the crack front suffers delamination, it is divided into several fronts with specific stress state in each one. Each condition is not considered in the equations to calculate CTOD by the ASTM 1820 standard [29]. This observation was previously reported by [24].
\nFor 7-mm-thick samples, all L-T samples presented a plastic fracture aspect, with lateral deformation and a large crack propagation region during CTOD, with no delaminations, but rather after the CTOD test, during sample break, as shown in Figure 10a, e. For T-L configuration, the surface fracture presented less plastic deformation aspect in comparison to L-T, with a flatter surface. The CTOD tests did not present any abrupt drop in force, but due to high plasticity, only a gradual drop of force was presented on CTOD graphic, as depicted in Figure 10d, h.
\nFor ACC-steel, 4 cases tested at −20 and −40°C presented delamination during CTOD test. Samples tested at 0°C presented no delamination occurrence. All the occurred delaminations in ACC-steel were considered significant according to the ASTM 1820 standard, two at −20°C and two at −40°C.
\nSome fracture surfaces of 15-mm samples are presented in Figure 11. In general, all delaminations occurred in AIR-steel that was not considered to be significant, presented a high zone of plastic deformation near it, as in Figure 11b. Strain hardening is followed by pop-ins in CTOD curve, presenting a drop on CTOD force with subsequent increase of force.
\nThis study presents two TMCP X80 plates of steel with different characteristics to assess fracture of toughness and mechanisms of crack propagation and delamination of the steels. Microstructural features, such as precipitates, phase boundaries, and grain boundaries, play an important role in determining the crack propagation by offering a weak path ahead of the crack tip. However, phase or grain boundaries can act as strong crack arrester when a crack propagates across grain boundary. Crack propagation rate inside a single-crystal grain is slower compared with the crack propagation rate along a crystal grain boundary. Figure 12 shows the frequency of dislocation tangle, LABs, HABs and CSL for both steels in order to evaluate the capacity to offer resistance to a crack. The fraction of HABs in all planes of AIR-steel sample is greater than ACC-steel. This behavior could be attributed to the banded microstructure, secondary phases, and segregation, which produces more grain boundaries by the presence of more phases and constituents. The presence of sub-grain boundaries or LABs has indicated the arrangement of dislocation inside a single-crystal grain, retarding the crack growth. The portion of sub-grain boundaries is higher in ACC-steel, decreasing the crack propagation rate by retarding the movement of dislocation. A higher fraction of dislocation tangles of ACC-steel could be related to the more lattice distortion due to bainitic transformation without diffusion and insufficient dynamic recovery, which also decreases crack propagation rate inside a single-crystal grain. Morales-Rivas et al. reported that \n
Distribution of boundary types of both steels: (a) AIR and (b) ACC steel.
The frequency distribution of main crystallographic orientations such as {001}, {101}, and {111} with about 15° deviation from ideal planes were calculated from EBSD data of AIR and ACC-steel samples and presented in Figure 13. The {111} and {101} planes were predominant in the transversal and rolling planes, respectively, of the AIR-steel sample with banded ferritic microstructure with the presence of iron carbide of its structure. The {001} family of planes were found in similar proportion among the rolling and normal planes. The {001}//ND textural components were dominant on a normal plane, and {111}//ND and {101}//ND were characterized by transversal and rolling planes, respectively, in ACC-steel with bainitic structure. Such orientation-dependent mechanical properties are largely attributed to texture and crystallographic orientation, causing anisotropy of mechanical properties. It is well understood that the formation of grains lying parallel to compact planes in BCC-ferritic steel with low carbon content such as {110} and {112} enhance ductile fracture by enhancing dislocation movements by adequate activated slip system, while cleavage occurs in non-compact planes such as {001} [40, 42, 43, 50]. It is suggested that cleavage fracture in AIR-steel found to be influenced by banded ferrite-pearlite microstructure and formation of segregation zone. The rapid cooling at the surface allowed the formation of finer bainite orientated towards {001}//ND. Blondé et al. have been discovered that low carbon content austenite grains transform first to martensite/bainite under accelerating cooling. Das Bakshi et al. [5] investigated the Charpy impact toughness of bainitic structure of microalloyed API X70 steels. They also characterized a dominance of a large fraction of {111}//ND grains accompanied by the presence of {001} and {101} because of the less of recrystallized austenite before the bainitic transformation of austenitic grains. However, this bainitic structure has less distortion rather than martensite structure, thereby, exhibited less risk of cleavage fracture.
\nFrequency distribution of main crystallographic orientations of (a) AIR-steel and (b) ACC-steel.
KAM values indirectly measure the dislocation density and the local plastic strain developed in the steel during rolling processing and were presented in Figures 6 and 7. The presence of banded ferrite—pearlite microstructure with the dispersion of secondary particles induced local stress sites concentration that would make AIR-steel sample prone to crack initiation due to the local high elastic energy stored. Inhomogeneous dislocation accumulation at interfaces traps carbon atoms, resulting in brittle carbide precipitates containing high dislocation density, leading to early fracture. It is included that the dislocation piles up concentrated at ferrite grain boundaries increase the risk of microcrack nucleation and crack propagation as well. However, the bainitic packet containing strain localization inside the soft ferrite lath phase decreases the strain gradient between the inside and at boundary region [51], resulting in higher strain hardenability and more fracture resistance.
\nFull constraint Taylor approach was used to evaluate the potential activated slip systems dependent on the grain orientations (Figures 6 and 7). It is found that the AIR-steels had a more distribution of high Taylor factor in comparison with ACC-steel, indicating the higher capability of storage of energy due to the accumulation of larger dislocation densities or dislocation piles-up, due to more active slip systems in a certain direction. ACC-steel with low Taylor Factor bainitic structure limits the deformation ability by not offering adequate slip systems. These assessments agree with the tensile results obtained in Figure 8 where AIR-steel presented a higher UTS/YS relation in comparison to ACC-steel.
\nAIR-steel presented higher intensity on {001} <110> to {111} <110> alpha-fiber, and {111} <110> to {111} <112> gamma-fiber than ACC-steel because of a lower finishing rolling temperature. AIR-steel presented stronger {100} <011>, known as rotated cube texture, than ACC-steel, which possess a low Taylor factor, i.e., high strain stored energy, or low further deformation ability. This result indicates intense cold deformation, low finish rolling temperature and low inter-pass rolling time [52, 53].
\nThis non-random distribution of crystal orientations influenced toughness properties, mainly by triggering delamination phenomena. The occurrence of delamination for 7-mm thick samples only occurred out of CTOD zone, after test, during sample break. For 15-mm thick sample, delaminations occurred during CTOD tests, causing pop-in and instant drop on the force.
\nCrystallographic orientation has been reported to be the major role causing impact toughness anisotropy of the steels [5, 8, 10, 17, 23, 54]. Some atomic planes are more important, as {110}, {112} and {123}, which are the major slip system for BCC steels [5, 8], and the {100}, which is the cleavage plane, the cube side lattice, for BCC steels [5, 8, 10, 17, 23, 54]. Also, it is important to bear in mind that the effect of these planes upon mechanical properties will depend on the volume, distribution and mainly on the position relative to the applied forces and planes presented during crack propagation at the crack-tip. For instance, for cleavage to occur, plane {100} must be presented perpendicular to the applied force, i.e., parallel to the fracture plane. To trigger the {112} slip system, the plane must be placed parallel to the applied force, i.e., perpendicular to the fracture plane.
\nThe alpha-fiber is a parallel fiber to the RD and presents some of the planes mentioned above as {100}, {112} and {113}. It was reported that the sharpening the {112} <110> and {113} <110> components results in improvement of impact toughness [5, 8, 25, 54]. As shown in Figure 5f, AIR-steel has a peak intensity at {001} <110>, followed by a dip and then peak at ϕ = 20–30°, region of {112} and {113} components. ACC-steel presents a plateau between ϕ = 10–35°. Values of intensity are higher for AIR-steel than for ACC-steel. Nonetheless, ACC-steel presented higher CTOD toughness with better isotropy, while AIR-steel presented lower values and anisotropy according to the geometry sample. These results are consistent with another study [8] in which was reported a higher fraction of {112} <110> at L-T than T-L and yet much higher CTOD results were obtained with T-L than L-T, showing no specific correlation of increasing toughness by increasing {112}.
\nThe obtained results show slight crystallographic differences between L-T and T-L configurations, and, for ACC-steel, these differences did not seem to affect toughness. However, it is suggested that the anisotropy displayed by AIR-steel between L-T and T-L geometries relies not only crystallographic orientation discrepancies but the microstructure anisotropy, as also reported [27]. 7-mm AIR-steel presented a higher fracture toughness for L-T configuration than T-L, in which the crack travels on a parallel plane to the rolling plane. Comparing L-T to T-L configurations of AIR-steel, nothing between is different regarding the chemical composition of phases and constituents, but only regarding the distribution and configuration of the microstructure.
\nFor AIR-steel, there is anisotropy of grain morphology and segregation configuration, as depicted schematically in Figure 14. Segregation is present on both geometries, but its configuration is different in each case, as for L-T geometry, segregation is transverse to the rolling plane while for T-L, segregation is coincident to the rolling plane as shown in Figure 14. Banded regions and the presence of aligned microphases and non-metallic inclusions, such as MnS, create an easy path for crack propagation, influencing toughness according to their volume, morphology and distribution [5, 15]. Ferrite resists the crack propagation better than bands composed of secondary phases and constituents, which act as brittle sites for crack initiation or as a concentrated stress spot, an easy path for the crack propagation [22]. For AIR-steel 7-mm L-T geometry, the fine equiaxed grain is encountered, while for T-L geometry, elongated rolled grains are found. Grain morphology of 7-mm ACC-steel was similar in the transverse and rolling planes, the tensile and toughness values were also similar in both directions.
\nSchematic illustration of the used AIR-steel. CTOD specimens in L-T and T-L configuration shown to better visualize the relationship between the microstructure on the CTOD crack propagation path and global plate microstructure.
For 15-mm thick samples, a general decrease is observed with a reduction of temperature. An approximate DBTT is −20°C, once, at this temperature, the values of toughness resulted from CTOD tests were close to a mean value of 0°C with −40°C condition tests. Overall, AIR-steel presented lower toughness than ACC-steel. As the temperature was lowered, the fracture started to present a more brittle-like behavior — this induced delamination occurrence, as well as a dropping tendency on toughness. Many 15-mm thick samples presented delaminations, and all delaminations were of divider type, as shown in Figure 15.
\nDelamination morphology: divide or arrester.
For all delaminations not considered significant, posterior plastic deformation and strain-hardening are achieved, increasing the CTOD force during test. These delaminations happen because the divider delamination branches the crack into two or more crack fronts, causing a relaxation of the triaxial tension towards a state of biaxial tension resulting in the decrease of the overall material constraint, promoting strain-hardening [22, 23]. In the cases of significant delamination, little or no strain-hardening ability was promoted. Figure 16 shows a fracture surface with non-significant and significant delamination, showing an aspect more plastic in the former case.
\nCTOD fracture surface of API X80 AIR-steel samples tested at different temperatures. Condition tested at (a) 25°C, showing a more plastic extension of CTOD zone, and plastic deformation on delamination edges; (b) −40°C, still exhibiting a plastic character in CTOD zone, but for a shorter extension. Yellow pointed line representing CTOD zone delimitation.
Many works studied the cause of delamination, assigning it to the presence of {100} cleavage plane [5, 8, 10, 23], but without further explanations. Some authors believe that delaminations are consequence mostly of the microstructure [26, 27]. In fact, microstructure exerts an effect on delamination occurrence, since AIR-steel presented more cases of delamination than ACC-steel, but not playing a major role. ACC-steel presented delamination on CTOD for 15-mm and on sample breaking for 7-mm, and yet presented a homogeneous microstructure with no detected inclusions or oxides, and not presenting mid-thickness segregation as AIR-steel.
\nDelamination phenomena are mainly governed by the crystallographic orientation presented next to the crack propagation path. It is necessary to fulfill embrittlement factors to satisfy the delamination criterion, i.e., many related parameters as temperature, crystallographic planes and orientations and presence of brittle phases. Regarding crystallographic orientation, the many previous works cited above correlated all delamination cases to the presence of {001}.
\nThe X-ray diffraction results showed low presence of {001} parallel to fracture plane in L-T and T-L geometries, and intense {001} at 45° to fracture plane. Figure 17 shows exactly the display of alpha-fiber according to L-T configuration. The delamination takes place traveling the {001} cubes face, macroscopically display at 45° to the fracture plane.
\nSchematic illustration containing half of SE(B) CTOD samples and crystallographic representation on fracture plane with alpha-fiber for L-T configuration.
\nFigure 18 illustrates the CTOD sample and the path of crack propagation, containing grains with random crystallographic orientations. The red-colored cube representing the {100} <011>, and the presence a possible clustering of {100} <011>. If two adjacent grains possess the same orientation, then they belong to the same grain. Therefore, it is assumed the existence of slight misorientation between schematic cubes. During the CTOD test, an external force produces internal stresses, causing transmission of forces in each atom lattice. This force transmission assuming the cubic lattice reaches a maximum shear component exactly when the vertex of the cube is pointing out to the applied force. In other words, a maximum shear in the lattice is achieved when the plane <011> is parallel to the applied force. That is exactly the role of the {100} <011> in delaminations occurrence. Applying a 45° rotation, the face of the cube coincides the imaginary plane of fracture. In this configuration, when an external force is applied, there is no shear component but only uniaxial tension directly on the cleavage plane {100}. Thus, plastic deformation is suppressed, lowering any mechanical property measured.
\nSchematic illustration of CTOD sample and the crystallographic orientations contained by the fracture plane. To a given a textured sample with high alpha-fiber, the first component is (001)[110] of the system {100} <011>, will present high intensity, existing the possibility of very similar oriented grains to be close to each other, forming a cluster.
The literature agrees with the proposed model of Figure 19. Mouriño et al. reported the lowest impact toughness at 45° from the RD. This result can be attributed to the highest volume fraction of {001} cleavage planes parallel to the 45° to the RD macroscopic fracture plane [54].
\nSchematic illustration of CTOD sample in L-T, T-L configurations, and tilted 45° from RD. Explaining how delamination occurs, and why the 45° tilted sample presents the worst toughness according to the literature.
Yang et al. presented three different rolled and heat-treated conditions for the same chemical composition and no macrosegregation. The final difference was grain morphology (elongated for the cold-worked) and texture. Results reported showed the lowest impact toughness and presence of delamination for the elongated grain morphology and the highest fraction of {100} on the fracture plane [25]. Joo et al. reported similar results, the lowest toughness at 45° with a high fraction of {100} planes [10]. In this study, samples were machined from the same rolled and treated plate, excluding any microstructure influence. It was concluded that the dominant aspect of anisotropy was the crystallographic texture. Furthermore, the anisotropy was enhanced when a near DBTT temperature was used [10]. These cited results are very similar to the obtained result in the present paper.
\nThe microstructure may have affected the delamination occurrence, once AIR-steel presented more delaminations than ACC-steel and showed a macrosegregation in the mid-thickness of the plate and elongated grains. It is also important to highlight that the observed delaminations occurred not only next to the mid-thickness of the samples, showing that microstructure banding is not the major or unique factor to trigger delamination. As expected, testing samples in RD or TD showed little difference for a homogeneous microstructure. Changing from RD to TD results only in slight crystallographic difference for a cubic system. AIR-steel presented a decrease of toughness mainly due to the change of polygonal to elongated microstructure.
\nToughness value is mainly controlled by crystallographic feature, and delaminations have a straight relation to the presence of {100} specifically on the plane of fracture [5, 8–10, 17, 23, 25, 54]. The alpha-fiber plays an important role because it aligns the [110] direction to RD, as shown in Figure 17, and, usually, the rolling process produces strong alpha-fiber, therefore, strong (100)[011]. This condition leads to a strong (100)[010] at 45° from RD, resulting in the lowest toughness as reported [10, 25, 54], and it is in agreement with the present work and proposed model in Figure 19. However, the 45° to RD configuration is not the cause of low toughness, but the presence of {100} on the fracture plane. Bakshi et al. obtained high toughness at 45° and low toughness at RD and ND (0 and 90° to RD) due to low {100} at 45° to RD [5].
\n\n
Delamination is governed by the presence of a specific crystallographic orientation. For the present work and others cited from literature, the {100} <011> is the main orientation that triggers delamination.
This work presented a schematic model of how the presence of {100} on fracture plane causes cleavage. The acting forces became nearly maximum uniaxial as Mohr theory, suppressing plastic deformation and cleavage fracturing.
The presented model clarifies the reason for generally rolled plates presenting lowest toughness at 45° to RD. Furthermore, the strong alpha-fiber is translated to strong {100} 45° to RD according to a cubic lattice system, causing cleavage through {100} coincident to the fracture plane.
The texture is the main factor causing anisotropy that affects toughness.
Macrosegregation and grain morphology affects the toughness of steel. As similar crystallography is obtained//RD and//ND for a cubic lattice, ACC-steel did not present toughness change for L-T and T-L configuration, while AIR-steel presented lower toughness on the elongated grain plane T-L.
ACC-steel and AIR-steel plates were produced by TMCP, with accelerated-cooling and air-cooling in the final production stage, respectively. Moreover, both steels presented differences in mechanical properties and fracture toughness due to anisotropy and heterogeneities in the microstructure. ACC-steel exhibited a granular bainitic microstructure, which increased hardness and fracture toughness compared to AIR-steel.
We would like to thank Tenaris Confab and Petrobras for the material donation, Brazilian Nanotechnology National Laboratory (LNNano) for the provision of the FEI ® Quanta 650FEG SEM/EBSD microscope, and X-ray Diffractometer. Special thanks are due to Pedro Brito and Eduardo Fonseca for their important review and suggestions of the manuscript. Vanessa da Silva from LNNano and Alberto Cury from USP/EESC are acknowledged for XRD measurements. This study was financed in part by the National Council for Scientific and Technological Development, Brazil CNPq, process 150215/2016-9; also H. Pinto is a CNPq fellow.
\nMaternal infections during pregnancy can have a direct impact on the developing fetus and in some infections can result in fetal demise. It is extremely important to screen women for infections when it is available and practical and to treat when necessary. The current screening tests recommended by the American College of Obstetricians and Gynecologists include rubella, hepatitis B, hepatitis C, human immunodeficiency virus (HIV), Group B streptococcus (GBS), tuberculosis and sexually transmitted infections including syphilis, chlamydia, and gonorrhea if risk factors are present [1]. The incidence of congenital infections in infants varies, with syphilis increasing dramatically from 639 cases in 2016 to over 1300 cases in 2018 in the United States [2]. Additionally, congenital cytomegalovirus, varicella zoster virus and herpes simplex virus diagnoses have increased over the last five decades [3]. Rubella has decreased since the introduction of Rubella immunization; prior to utilization of the immunization, over 100,000 infants were born worldwide with congenital rubella syndrome (CRS). By 2014, a 95% decrease in cases of CRS was observed in countries that followed the immunization schedule [4]. Thus, it is critically important that research efforts continue to prioritize the development of immunizations and treatments plans for all viruses that can result in congenital fetal infection in an attempt to minimize the substantial long-term morbidities that result.
Chorioamnionitis is the term that has been used for decades to describe infection and/or inflammation of the chorion, amnion, or both. This has been further delineated into a “clinical” diagnosis based on maternal symptoms, and a “histological” diagnosis based on the pathology of the placenta following delivery. Clinical signs and symptoms are used to diagnose clinical chorioamnionitis, and include maternal fever, uterine fundal tenderness, maternal and/or fetal tachycardia and purulent amniotic fluid [5]. The most common bacterial organisms to cause chorioamnionitis are Ureaplasma urealyticum and Mycoplasma hominis. Histological chorioamnionitis is diagnosed by observing neutrophil infiltration into the chorion and amnion [6]. The variation in the definition of chorioamnionitis has resulted in confusion in neonatal management as well as difficulty in assessing the long-term impact of chorioamnionitis on development. Therefore, intra-amniotic infection (IAI) has been developed to replace the prior diagnosis of chorioamnionitis [7].
IAI was updated in 2017 by the American College of Obstetricians and Gynecologists into three categories which are readily diagnosed. Isolated maternal fever (IMF) is the first category, in which the mother has a single intrapartum temperature of ≥39.0°C or a temperature of 38.0–38.9°C that persists for 30 min, with treatment recommendations including the consideration of broad-spectrum antibiotics [7, 8]. Given the numerous potential causes of maternal fever, the utilization of antibiotics is at the providers’ discretion. Suspected IAI is diagnosed when the mother has an elevated temperature (≥39.0°C) or a slightly elevated temperature (38.0–38.9°C) along with one of the following risk factors: maternal leukocytosis, purulent cervical drainage or fetal tachycardia [7, 8]. Confirmed IAI is diagnosed with a positive amniotic fluid test or placental pathology demonstrating histologic evidence of infection [7]. Similar to the previously used histological chorioamnionitis, a criticism of this diagnosis is that it is made after the clinical situation has resolved, and thus does not aid in the acute management of the mother or the infant. Both suspected and confirmed IAI diagnoses should result in treatment with intrapartum antibiotics and antipyretics [7].
IAI is present in nearly 50% of very early preterm birth [9], after which multiple complications can occur and a wide array of neonatal morbidities and mortalities are observed. This has led to speculation that IAI is directly impacting the fetal and neonatal development and outcomes, as well as potentially resulting in preterm birth, which then impacts development and outcomes. The majority of studies that have investigated this question utilized diagnoses of chorioamnionitis, which included both clinical and histological cases. Given the variation of diagnoses included in these studies, it is not surprising that the results have also been varied. A large study of 2390 extremely preterm infants (born <27 weeks’ gestational age) from sixteen centers across the United States found infants exposed to histological and clinical chorioamnionitis had an increased risk of cognitive impairment at 18–22 months’ corrected age [10]. A separate study of 350 infants found that while gestational age was significantly lower among those with exposure to histological chorioamnionitis, there was no association with intraventricular hemorrhage, white matter injury around birth, or differences in cognitive or motor outcomes at 18–24 months’ corrected age [11]. Additional studies have found weak causal or associative roles of chorioamnionitis with cerebral palsy risk [12] and no increased risk of white matter injury on magnetic resonance imaging (MRI) following histological chorioamnionitis in premature infants [13]. Additional investigation is required with the new IAI definitions to determine if there are consistent findings with developmental outcomes in those diagnosed with IAI.
TORCH infection is a mnemonic that has classically been used to describe congenital infections that can impact fetal development. In the past, TORCH represented Toxoplasmosis, Other (syphilis, varicella-zoster, parvovirus B19 and newer pathogens such as Zika), Rubella, Cytomegalovirus and Herpes Simplex Virus. However, as more pathogens are being discovered and the “other” category is expanding, some experts feel the mnemonic is not as relevant today.
Toxoplasma gondii is an obligate intracellular protozoan which typically causes mild illness in most immunocompetent individuals [14, 15]. While a large portion of infected children and adults are asymptomatic, Toxoplasmosis is considered one of the major causes of death linked to foodborne illness in the United States. If an immunocompromised individual, pregnant woman, or fetus/infant acquires the infection, there can be severe, even fatal, consequences [14, 15]. Illness can range from non-specific systemic symptoms such as fever, lymphadenopathy and hepatosplenomegaly to congenital toxoplasmosis (CT), which is classically described as a triad of chorioretinitis, intracranial calcifications and hydrocephalus. CT can lead to loss of vision and hearing, decreased cognitive function, and neurodevelopmental delay if untreated [14, 16–18].
T. gondii exists in three forms: tachyzoite, bradyzoite, and sporozoite. The definitive hosts are members of the Felidae family, but warm-blood mammals can also serve as intermediate hosts [17]. Felines can acquire T. gondii through the ingestion of tissue cysts containing bradyzoites in infected prey or through the ingestion of oocysts containing sporozoites in anything contaminated with feces from an infected cat. They can excrete un-sporulated oocysts in their stools 3–30 days after infection and can shed for 7–14 days. If in the right climate (such as warm and humid), the oocysts can sporulate for 1–5 days, after which they can remain infectious for years. If the tissue cysts found in intermediate hosts or the sporulated oocysts are ingested by humans, they transform into active tachyzoites. The tachyzoites then primarily infect the central nervous system, eyes, musculoskeletal system, and placenta by infecting nucleated host cells to bypass the blood brain barrier and placental barricade. Incubation is 7 days with a range of 4–21 days [14, 15, 18].
For pregnant women who have an acute infection with T. gondii, the timing can be crucial and dictates the treatment course. Typically, the earlier in pregnancy that acute infection occurs, the lower the rate of transmission to the fetus. Unfortunately, there is an increased severity of illness if transmission occurs earlier in the pregnancy [14, 15]. The reverse is true for infection later in pregnancy (such as during the third trimester), during which there is a high rate of transmission but with less severe illness in the fetus.
The diagnosis of primary or latent infection is made primarily using serologic tests. Toxoplasma-specific Immunoglobulin G (IgG) and Immunoglobulin M (IgM) can be performed routinely at non-reference laboratories. Any positive IgM results are then submitted to reference laboratories that can perform additional testing for confirmation [18]. If a pregnant woman is found to have acute infection, then an amniocentesis can be performed, and the fluid can be sent for polymerase chain reaction (PCR) testing. If the PCR is negative and the fetus is believed to have not acquired the infection, the next best step is treatment in the mother with spiramycin in an attempt to prevent transmission [14, 15, 17, 18]. If, however, the fetus is thought to be infected, then the mother is started on a combination of pyrimethamine, sulfadiazine, and folinic acid. Spiramycin, a primarily bacteriostatic macrolide that has activity against some gram-negative and gram-positive organisms as well as some spirochetes, is unable to cross the placenta whereas the combination of anti-parasitic medications can cross the placenta and thus can aide in treatment of the fetus [18, 19]. The combination is also used for fetal infection confirmed at or after 18 weeks of gestation or maternal infection acquired during the third trimester [14, 17, 18]. As untreated CT can lead to fetal demise or death within the first few days of life, and chorioretinitis can develop in a significant proportion of infants whose mothers were untreated, it is imperative to diagnose and start treatment in a timely manner [18].
Once an infant with suspected CT is born, he or she should be thoroughly examined and evaluated. Serologies, a complete blood count (CBC), hepatic function tests, blood PCR, urine PCR, cerebrospinal fluid (CSF) PCR, and CSF studies including glucose level, protein, and cell count, should be sent [18]. The newborn should also have ophthalmologic, auditory, and neurologic evaluation including imaging of the brain [18]. Infected infants should receive treatment regardless of any clinically apparent symptoms, as a large proportion of infants with asymptomatic CT at birth go on to develop visual/hearing impairment, learning disabilities, and psychomotor delay [15, 16, 18, 20]. Treatment consists of the same anti-parasitic combination of pyrimethamine, sulfadiazine, and folinic acid [18, 19]. If CSF studies show an elevated protein concentration (greater than 1 g/dL) or there is evidence of severe chorioretinitis, then a corticosteroid such as prednisone is added until there is a decrease in protein concentration in the CSF or resolution of severe chorioretinitis [15, 18, 19]. Treatment is continued at least though 12 months of age, with consideration of shorter treatment duration for infants who remain asymptomatic for the first three months of life [18, 19]. For those infants who are asymptomatic with positive Toxo-specific IgG but negative IgM and Immunoglobulin A (IgA), there should be repeat IgG testing every four to six weeks until disappearance of IgG. There is no clear consensus on the treatment of these infants [18, 19].
Studies looking at the outcomes of infants with CT have shown significantly better neurologic and developmental outcomes in those that were treated than those who were not [21]. It is important to note that compared to their uninfected siblings, the children that received treatment had a lower level of cognitive function though there was no deterioration over time. In terms of ophthalmologic outcomes, it was found that when followed up to 22 years of age, new ocular lesions could be detected in adolescence which points to the importance of continued ophthalmologic evaluation.
Treponema pallidum, a thin, motile spirochete, is the organism that causes syphilis [18], a sexually transmitted infection that can also result in congenital infection to a fetus. While there was initially a decline in the cases of syphilis observed in the United States in 2000–2001, an alarming resurgence has recently been noted. There has been an increase of 72% in the number of reported primary and secondary cases in the United States from 2013 to 2017, with the number of congenital syphilis cases increasing more than 150% from 2013 to 2018 [22–24]. It is thought that the increase in methamphetamine use, having sex with a person who injects drugs, injection drug use and heroin use are the primary factors that are leading to this dramatic increase in syphilis cases [22, 25].
Acquired syphilis is typically divided into three stages: primary, secondary and latent. During the primary stage, painless indurated ulcers form on the skin or mucous membranes of the areas exposed and heal spontaneously in a few weeks. The secondary stage, typically 1–2 months after the primary stage, is characterized by a maculopapular rash that typically includes the palms and soles, lymphadenopathy and mucocutaneous lesions including condylomata lata [18]. Finally, the latent stage occurs when there are no clinical signs or symptoms of infection, but an individual remains seroreactive [18]. T. pallidum can infect the central nervous system (CNS) during any stage, resulting in neurosyphilis. Transmission to the fetus during pregnancy can occur at any point, with primary and secondary syphilis having the highest rates of transmission at 60–100% [18].
It is recommended that all women be screened for syphilis early in pregnancy with a nontreponemal test, with repeat testing later in pregnancy for high risk individuals. These tests include the Venereal Disease Research Laboratory (VDRL) slide test and the rapid plasma reagin (RPR) test [18]. These nontreponemal tests utilize an antigen that reacts in the presence of antibodies (to syphilis). However, given that the antigen is not specific for syphilis and is a component of cell membranes, false positives may result from other infections including varicella and measles, or by tissue damage observed in connective tissue disease and even pregnancy itself [26]. Therefore, a positive nontreponemal test should be followed by a confirmatory test such as fluorescent treponemal antibody absorption (FTA-ABS) or T. pallidum particle agglutination (TP-PA) tests. Additionally, any person found positive for syphilis based on screening and confirmatory testing should also be screened for human immunodeficiency virus (HIV) given the high rate of co-infection.
Treatment for syphilis is parenteral penicillin G; if an individual is allergic to penicillin G, they should undergo desensitization due to the lack of proven efficacy of alternative agents in this setting. Lack of treatment during pregnancy can result in stillbirth and neonatal death in nearly 40% of women with primary and secondary stage disease, 40% of infants being infected and only 20% of infants being healthy and uninfected [27]. Additionally, fetal infection can result in anemia, hepatomegaly and hydrops [24]. Treatment of the infant should not be delayed, as early treatment may prevent neurologic sequelae [24].
A serological diagnosis is made on the infant if the nontreponemal titer (VDRL or RPR) is fourfold higher than that of the mother (both samples should be obtained around the same time), if the nontreponemal titer persists or increases after birth, or if the treponemal antibody titer (FTA-ABS or TP-PA) remains positive at 12–18 months of age. The choice of test on the infant is dependent on the test that the mother had received, as the titers will need to be compared [18]. A complete evaluation, including complete blood cell count (CBC), liver function tests, obtaining cerebrospinal fluid (CSF) to test for VDRL reactivity, ophthalmologic examination and long-bone radiographs to assess abnormal ossification, radiolucencies or dislocation of epiphyses is then needed [28]. Neuroimaging should be considered if there are any concerns for central nervous system involvement [18]. Ten days of treatment with parenteral penicillin G is typically used in infected infants, with close follow up required. Titers should be repeated by 3 months of age and noted to be declining, with nonreactivity noted by 6 months of age [28]. If the mother received appropriate treatment that was administered >4 weeks before delivery, and the infant has a normal physical examination with the titer equal to or less than fourfold the maternal titer, then no evaluation is recommended. However, inadequate treatment in the mother should result in evaluation of the infant and treatment with penicillin G for 10 days [28].
Clinically, nearly half of infants do not have any apparent signs of infection, although bone lesions and hematologic and hepatobiliary abnormalities may be present, with hepatomegaly one of the most common findings [24, 29]. Infants that develop symptoms may have rhinitis in the first week of life, in which persistent white discharge (“snuffles”) occurs which contains spirochetes [29]. Additional symptoms can include generalized lymphadenopathy and a maculopapular rash [29]. Long term outcomes of infants not appropriately treated can include sensorineural hearing loss, interstitial keratitis, secondary glaucoma, corneal scarring, vision impairment, Hutchinson teeth (smaller teeth that are widely spaced with notches), saber shins (sharp anterior bowing of the tibia), frontal bossing, saddle nose, gummas (soft, non-cancerous growth) and scarring [29]. Life-long disabilities can occur in congenital syphilis infections if infants are not appropriately screened and treated [28].
Varicella-zoster virus (VZV) is a herpesvirus that is transmitted by respiratory droplets, direct contact with skin lesions, and transplacentally during pregnancy [30]. Infants that are exposed to VZV during the last few weeks of pregnancy may develop neonatal varicella which can be quite severe; congenital varicella syndrome (CVS) develops in infants exposed during the pregnancy, with the risk being highest if the exposure occurs in the first trimester [30]. Infants exposed after 20 weeks’ gestation only have about 2% chance of developing CVS [31]. Infants with CVS most commonly have skin lesions in a dermatomal distribution followed by neurologic defects, eye disease and skeletal anomalies [31]. Neurologic defects can include cerebral cortical atrophy and ventriculomegaly. Unfortunately, CVS is fatal in about 30% of cases within the first month of life [32].
The monovalent vaccine approved in 1995 and the quadrivalent vaccine introduced in 2005 have impacted the prevalence of congenital infection as seroprotection is nearly 100% after 2 doses of the vaccine [18]. Thus, at this time, CVS is considered an extremely rare disorder.
Human parvovirus B19 is a nonenveloped, single-stranded deoxyribonucleic acid (DNA) virus with humans as the only host [18]. The virus replicates in erythrocyte precursors and is transmitted via respiratory tract secretions, exposure to blood or blood products, and vertically [18]. While it often causes a mild respiratory tract infection with a “slapped cheek” rash, it can be lethal to a fetus, with the risk of death being as high as 10% [33]. The incidence of parvovirus B19 infection during pregnancy is 3–4%, with the transplacental transmission rate approaching 30% [34]. Fortunately, approximately 50–75% of women of reproductive age are immune to parvovirus B19 [35]. The timing of infection during pregnancy does alter the risk of fetal death, with first trimester infections resulting in up to 71% risk of fetal loss [34]. The difficulty in diagnosing the virus during pregnancy arises in the lack of symptoms that most adults experience, and as many as 70% of women would have no symptoms if infected during pregnancy [34]. Arthropathies are one of the most common symptoms and should raise suspicion for possible infection [34]. Additionally, the presence of fetal ascites or pericardial effusions on ultrasound should trigger high suspicion as well [33].
Fetal hydrops, or abnormal accumulation of fluid/edema in two or more compartments, is common in the setting of Parvovirus B19 infection, with a meta-analysis finding a 9.3% pooled incidence, as well as an increased risk of fetal loss, spontaneous abortion and stillbirth [36]. Parvovirus B19 is among the most common causes of non-immune fetal hydrops, and while spontaneous resolution of infection can occur, only about 5% of cases with hydrops will show spontaneous resolution of the infection with disappearance of hydrops on follow up ultrasounds [37].
Severe anemia and thrombocytopenia occur in utero following parvovirus B19 infection, along with myocardial dysfunction [38]. These factors together are likely the etiology of the fetal hydrops. In utero transfusions (IUT) are often necessary and reduce mortality rates when compared to expectant management. A meta-analysis found IUT was performed in 78% of hydropic fetuses compared to 29% of non-hydropic fetuses, with the difference likely due to the hydropic fetuses at higher risk of demise [37]. Complications may occur in up to 5% of cases, especially if the fetus is likely more sensitive to vascular overload [38]. Thus, intrauterine exchange transfusions (IUET) have also been attempted in cases of fetal hydrops in the setting of parvovirus B19 infection. Unfortunately, thus far it results in similar survival rates as IUT and does not seem to be clinically superior as a treatment modality [38].
Longer-term testing reveal abnormal neurodevelopment following intrauterine parvovirus B19 infections in those also diagnosed with hydrops. Brain abnormalities including parenchymal calcifications, venous infarction, arterial infarction, cerebellar hemorrhage, and cortical malformations including diffuse cortical dysplasia and polymicrogyria have been described in congenital parvovirus infections [39]. If there are no abnormalities on imaging and hydrops resolves prior to delivery, one study found normal neurodevelopment in survivors at 1- and 5-year follow-up [40]. While the overall risk of mortality and morbidity are high, there is the potential for a normal outcome in select cases of congenital parvovirus infections.
Zika virus, ZIKV, is an emerging flavivirus that first became apparent internationally after Brazil declared a national public health emergency in 2016 followed by the World Health Organization declaring the outbreak a public health event of international concern [41]. The virus was first identified in 1947 in Uganda, after which cases of human infection have been infrequent and fairly localized [41]. ZIKV is transmitted by infected Aedes spp. mosquitoes, sexual contact and blood transfusions [42]. Around 80% of ZIKV that occur in adults are asymptomatic, with other cases having a mild febrile illness, headache, rash, fever and conjunctivitis [42]. However, severe neurologic sequalae can also occur in adults.
Congenital Zika syndrome (CZS) is variable in the presentation and severity with only a subset of infants that were exposed having apparent signs and symptoms at birth [41]. Infants exposed to ZIKV in utero are expected to survive, however a severe phenotype can result, particularly when exposure occurs in the first trimester [43]. ZIKV replication in brain tissue can continue after birth, and thus infants that are initially asymptomatic may develop symptoms within the first year of life [41]. The phenotype of CZS appears to consist of severe microcephaly and possibly a partially collapsed skull, thin cerebral cortices with subcortical calcifications, macular scarring, congenital contractures and marked early hypertonia [41]. Microcephaly is the most common symptom, occurring in up to 91% of CZS, and is often severe with the mean occipitofrontal head circumference falling 3–4 standard deviations below normal [43]. Both the central and peripheral nervous systems are impacted, with resultant effects on musculoskeletal, auditory and ophthalmologic systems and symptoms including conductive hip dysplasia, abnormal posturing of extremities, conductive hearing loss and abnormalities of the retina and optic nerve [43]. Up to 55% of infants with CZS have structural ocular abnormalities, making visual screening and interventions critically important to occur early in life to allow for neuroplasticity optimizing the outcomes [44]. This has led to the recommendation of any infant with suspected CZS or exposure to ZIKV to have an ocular examination before hospital discharge and again at 3 months of age [44].
A meta-analysis of 42 articles revealed the most common brain abnormalities following ZIKV exposure in utero, including decreased brain volume, increased extra-axial cerebrospinal fluid space, subcortical calcifications, microcephaly, ventriculomegaly, malformation of cortical development, basal ganglia calcifications, and mega cisterna magna [45]. These findings support the concept that ZIKV interferes with normal neuronal migration during development which then impacts the brain development. The major neuronal migration is occurring before the 25th week of gestation, making exposure to the virus in the first and second trimesters the most devastating. Infants with ZIKV exposure and no apparent congenital syndrome are also at risk for abnormal neurodevelopmental outcomes, as evidenced in a recent study of 70 infants followed to age 18 months [46]. These infants had confirmed exposure to ZIKV but no findings to support CZS, and despite the normal head circumference, had subsequent neurodevelopmental deficits develop over the first year of life [46]. As studies continue and longer-term outcomes become known, it is critically important to follow any infant with ZIKV exposure closely.
Rubella is caused by a single stranded ribonucleic acid (RNA) virus which is highly contagious and only transmitted between humans [18, 47]. It is usually spread through respiratory droplets and in most cases will result in a mild viral disease. Symptoms may include fever, rash, malaise and adenopathy. The virus is able to infect cells of the respiratory tract and then spread via the systemic circulation to multiple organ systems, including the placenta [48]. When the infection occurs during pregnancy the virus can be transmitted to the fetus and result in death of the fetus or a range of congenital anomalies known collectively as Congenital Rubella Syndrome (CRS) [18]. The timing of when a pregnant woman contracts the virus appears to be related to the risk of congenital infection and fetal defects. Studies estimate that maternal infection occurring during the first 12 weeks of gestation has roughly a 90% chance of congenital infection with the risk of defects nearly 85% [49]. When congenital infection occurs during the first trimester, hearing defects, heart defects, neurologic damage, and ocular defects appear more commonly. CRS is a combination of these defects but most classically is described as a triad of cataracts, congenital heart disease, and sensorineural deafness [49, 50]. Other manifestations include intrauterine growth restriction (IUGR), hepatomegaly, splenomegaly, thrombocytopenia and dermal erythropoiesis (commonly known as a “blueberry muffin rash”) [18].
Pregnant women in the United States are tested for rubella immunity by serologic screening. Those who have had a natural infection or have received at least one dose of the rubella vaccine tend to have lifelong immunity [18]. Those women who are found to be non-immune should receive one dose of the vaccine after childbirth, as vaccination during pregnancy has theoretical teratogenic risks due to the vaccine being live [18]. If a pregnant woman is exposed to the rubella virus, they should have serologic testing for rubella-specific IgM and IgG. If she is found to have rubella-specific IgG, then she is considered immune. However, if there is no IgG detectable at the time of exposure then convalescent serologies are obtained 3 and 6 weeks after exposure, with IgG reactivity at these time points indicating a recent infection [18]. Unfortunately, there is no treatment for rubella outside of supportive measures.
When congenital infection is suspected, diagnosis can be done by testing for rubella-specific IgM in fetal blood or detection of the virus in amniotic fluid [49]. Postnatally, an enzyme-linked immunosorbent assay (ELISA) can also be done for rubella-specific IgM. If positive, then confirmatory testing is done by reverse transcription polymerase chain reaction (RT-PCR) of nasopharyngeal swabs, urine, or oral fluid [47, 49]. In some infants the virus can be detected in nasopharyngeal secretions and urine for over a year [18, 49]. While there is no treatment for CRS, diagnosis is important in terms of follow up. Due to the risk of cataracts among other ocular abnormalities (including microphthalmia, glaucoma, chorioretinitis), hearing loss, neurologic manifestations (such as developmental delay, autism), and endocrine disorders (including diabetes, thyroid disease) children with CRS must be evaluated periodically for management of these potential complications [48–50]. The introduction of the vaccine has resulted in a significant decline in cases of rubella infection and CRS in the United States, with an average of 14 reported rubella cases a year and 4 CRS cases a year from 2001 to 2004 [51].
Cytomegalovirus (CMV) is a double stranded deoxyribonucleic acid (DNA) virus that is universally found and generally causes mild or subclinical symptoms in most children and adults [18, 52]. It can be transmitted via contact with infected secretions, transfusion of blood products from infected donors, organ transplants from infected individuals, or vertically [18]. When it is vertically transmitted, CMV has the potential to cause severe and permanent sequelae [18, 52, 53]. CMV is known as one of the most common congenital viral infections and is the leading, non-genetic cause of sensorineural hearing loss in children in the United States [18]. It can be transmitted to the fetus by crossing the placenta, through contact of infected cervical secretions during birth, or perinatally by ingestion of breast milk containing the virus [18]. When CMV is transmitted in utero, it can be due to primary maternal infection during pregnancy, reactivation of a prior infection, or reinfection with a different strain despite presence of maternal antibodies [54, 55]. Reactivation and reinfection are more common than a primary infection; however, the latter tends to cause more severe sequelae especially if infection occurs earlier in pregnancy.
Of those infants whose mother had an acute infection during pregnancy, 30–40% will have congenital CMV (cCMV) [18, 55]. Infants with cCMV are symptomatic in 10–15% of the cases, with half to two-thirds of these infants developing sensorineural hearing loss (SNHL) later in life [55]. Symptoms at birth can include thrombocytopenia, hepatomegaly, splenomegaly, microcephaly, periventricular calcifications in the brain, chorioretinitis, hepatitis, and SNHL. Long term outcomes include progressive SNHL and neurodevelopmental delay [18, 53, 55]. Of the infants who are asymptomatic at birth, around 15% will later develop SNHL [18]. Imaging of the fetal brain can be completed in utero via transvaginal ultrasound or with magnetic resonance imaging (MRI). cCMV can result in germinolytic cysts, lenticulostriate vasculopathy, temporal lobe and occipital cysts as well as cerebellar hypoplasia and migrational disorders including polymicrogyria [52]. Periventricular calcifications is the most frequently reported finding on brain imaging of cCMV cases, impacting 34–70% of diagnosed patients [56].
Testing during pregnancy is not routinely done, but serologic testing can be performed if a pregnant woman has been exposed or is suspected of having CMV infection. CMV-specific IgM has low specificity as it can persist for 6–9 month following primary infection and can also be detected during reactivation [54]. CMV IgG avidity index however can be used to confirm primary infection; avidity testing is a method to measure the strength of the bonding between antibodies and the virus. Low avidity would indicate recent infection while high avidity takes time to occur and would indicate a past infection. There is no current recommended treatment for acute CMV infection during pregnancy [18, 54].
There is also no current routine testing for CMV in infants. Some states have mandated targeted CMV screening for those who fail their routine newborn hearing screen, however it is important to note that targeted screening will miss those newborns who are asymptomatic at birth but still at risk for developing SNHL later in life [18]. For symptomatic infants, the diagnosis of cCMV can be made postnatally if testing is done within 3 weeks of birth as to avoid the difficulty of differentiating between intrauterine and perinatal infection [18, 54, 57]. CMV can be isolated from the urine, saliva, respiratory secretions, blood, or cerebrospinal fluid [18]. Viral cultures, rapid shell vial cultures, and PCR can be completed [54]. Treatment for those infants who are symptomatic regardless of CNS involvement includes intravenous ganciclovir or oral valganciclovir [18, 54, 58]. The latter is preferred due to ease of administration as duration of treatment is six months. If there are concerns for abnormal gastrointestinal absorption due to other factors, treatment can be started with IV ganciclovir [54]. Studies have found that those who have anti-viral treatment started within the first month of life have significantly improved audiologic and neurodevelopmental outcomes at 12 and 24 months of age compared to those who do not [53]. Treatment with either valganciclovir or ganciclovir can cause significant neutropenia; absolute neutrophil counts should be monitored weekly for the first six weeks of treatment, followed by screening at eight weeks of treatment, and thereafter monthly for the duration of treatment [54]. Infants with mild symptoms or isolated SNHL are not recommended to receive antiviral treatment at this time due to lack of data in this population [54].
Long term outcomes to consider in children with cCMV include SNHL and neurodevelopmental delay. These children should have frequent audiologic assessments as SNHL can develop and/or progress after the newborn period [54]. While there are no established universal guidelines for hearing evaluation, studies indicate that screening should continue for at least the first four years of life after which late-onset SNHL is seldom seen.
Herpes simplex viruses are large, double-stranded DNA viruses with two types, HSV-1 and HSV-2 [18]. Traditionally, HSV-1 can cause vesicular lesions in areas above the waist while HSV-2 involves areas below the waist. It is, however, becoming increasingly more common to see genital HSV-1 lesions. Both types are able to cause herpetic disease in neonates when acquired from the mother. Transmission can occur during the birthing process via contact with genital lesions, an ascending infection, intrauterine, or postnatally from contact with lesions [18, 52]. A primary genital HSV infection in the mother near delivery has 10–30 times the risk of transmission compared to a recurrent infection. This is thought to be due to lower concentrations of transplacental HSV antibodies in the neonate [18, 59]. Unfortunately, defining an infection as primary versus recurrent may not be straightforward, as women can be asymptomatic and may be unaware that they have had a prior infection with HSV. Furthermore, viral shedding can occur in the absence of clinical symptoms [59].
If a pregnant woman does have genital lesions characteristic of HSV near delivery, then swabs of the lesions can be sent for viral culture and PCR with serologic testing to determine the type. From these results, women can be classified into four different categories: documented first primary infection, documented first episode non-primary infection, assumed first episode (primary or non-primary), or recurrent infection (see Table 1 adapted from Kimberlin et al.).
Diagnostic tests for Herpes simplex virus (HSV) Antibodies and Culture/PCR. This table describes the classification of HSV infection based on culture or PCR test results as well as HSV-1 and HSV-2 antibody test results.
Women classified as having a primary infection or first episode can be treated with oral acyclovir for 7–10 days [18]. Those with a recurrent episode can be treated with the same or higher dose for 5 days [18]. If a woman has a known history of HSV then suppressive therapy should be started at 36 weeks’ gestation to decrease the risk of recurrence at delivery, although this will not entirely suppress shedding [60]. Other preventative methods include avoiding invasive fetal monitoring, such as fetal scalp electrodes, and opting for elective cesarean sections when lesions are present at the time of delivery [52, 60].
Neonatal HSV can have different manifestations. SEM disease includes disease of the skin, eyes and/or mouth; 45% of infants with HSV will have SEM. Another 30% of infants with HSV will have localized central nervous system (CNS) disease with or without skin involvement. The remaining 25% of infants with HSV will have disseminated disease which can involve multiple organs, most commonly the liver and lungs [18]. The onset of disease varies between the different manifestations, with SEM disease presenting at 5–11 days of life, CNS disease presenting between 8 and 17 days of life, and disseminated disease presenting between 10 and 12 days of life [61]. Initial symptoms may be non-specific and include feeding difficulties, lethargy, seizures, suspected sepsis, vesicular rash or severe liver dysfunction, with as many as 30% of infected neonates not having skin lesions [52, 60]. As there can be high morbidity and mortality rates in newborns with HSV, it is imperative to diagnose and initiate treatment as soon as it is suspected [18].
Guidelines have been published on the management of asymptomatic neonates born to women with active genital lesions [59]. In newborns whose mothers have a history of genital HSV prior to pregnancy and present with active lesions at delivery, there is a low risk of transmission. However, the infant should still have surface swabs of the mouth, nasopharynx, conjunctivae, and anus obtained for culture and PCR as well as serum HSV PCR sent at 24 h of life. Waiting to send samples until 24 h of life ensures that any positive results would represent active viral replication in the infant and not maternal contamination [59]. Intravenous acyclovir is not started in this situation unless the infant becomes symptomatic, or the surface swabs and/or serum are positive. This would confirm infection and require a lumbar puncture to obtain cerebrospinal fluid (CSF) for PCR testing. The result of the CSF PCR is key in determining treatment duration. If the CSF and serum HSV PCR are negative, then empiric IV acyclovir is administered for a total of 10 days to prevent progression from infection to disease. If the CSF PCR is positive, then treatment should be administered for 21 days [59]. After the treatment course has completed, a repeat lumbar puncture is necessary in cases of CNS disease to document clearance. If the repeat CSF HSV PCR is still positive, then acyclovir is continued for another 7 days. A repeat lumbar puncture is obtained to show clearance. This process is repeated until the CSF is negative. Any infant who undergoes a treatment course for HSV disease should have suppressive therapy with oral acyclovir for 6 months after the completion of parenteral treatment (see Figures 1 and 2) [59, 62].
Infant evaluation in suspected exposure to Herpes simplex virus (HSV). This flow diagram, adapted from Ref. [59], describes the infant evaluation(s) to complete if there was concern for maternal HSV infection around the time of delivery due to the presence of lesions.
Infant treatment recommendations for suspected congenital Herpes simplex virus (HSV) infection. Tis flow diagram, adapted from Ref. [59], describes treatment regimens based on infant symptoms.
In the case that an asymptomatic neonate is born to a mother with active genital lesions but does not have a history of genital HSV prior to pregnancy, then the importance lies in distinguishing whether it is a primary, non-primary or recurrent infection [59]. The mother should not only have the swabs sent for PCR testing and culture but should also have serum serological tests performed for HSV-1 and HSV-2 antibodies. The infant requires evaluation at 24 h of life with HSV surface cultures and PCR testing of the serum and CSF. The CSF samples should also be sent for cell count and chemistries, with screening serum alanine aminotransferase obtained. IV acyclovir would be started empirically after obtaining the samples at 24 h of age while awaiting results. Once the maternal testing is resulted, maternal classification can then be determined as shown in Table 1. If the mother is deemed to have a first episode primary or non-primary infection, then treatment of the infant would include 10 days of IV acyclovir for a normal evaluation (infant remains asymptomatic, negative CSF and serum HSV PCR, normal CSF indices, and normal serum ALT), 14 days for an abnormal evaluation (positive serum HSV PCR, symptomatic infant, or abnormal ALT) and 21 days for CNS infection (positive CSF PCR or abnormal indices) [59]. A neonate with a positive CSF HSV PCR, regardless of the maternal classification, would be managed as described above for HSV disease. It is important to note that if the infant becomes symptomatic at any point, even prior to the testing obtained at 24 h of life, then immediate evaluation and treatment should be initiated [59]. Other risk factors that may prompt testing and treatment prior the 24 h include: prolonged rupture of membranes (>4–6 h) and prematurity (<37 weeks’ gestation) in the setting of maternal genital lesions characteristic of HSV [59].
Only 10% of infants survive in untreated HSV disseminated disease with 50% of infants surviving in untreated HSV CNS disease [61]. Inadequately treated or untreated HSV SEM disease can progress to either disseminated or CNS disease; those that survive have a significant proportion that show some neurologic sequelae, namely in the form of motor, speech, and developmental delay [61]. Outcomes, especially mortality, improve the earlier that treatment is initiated, making it imperative to evaluate and begin empiric treatment whenever HSV infection is suspected [61]. Oral suppressive therapy has also been shown to improve neurodevelopmental outcomes at 12 months of age compared to those that did not receive long-term antivirals, suggesting that ongoing neurologic injury may occur in infants affected by HSV disease [62].
A review of additional viruses that can impact infants exposed during pregnancy is provided below. These viruses have been associated with a range of adverse outcomes in infants with prenatal/perinatal exposure, however they remain uncommonly diagnosed or the impact on the fetus remains extremely varied. However, given the increased risk of potential adverse outcomes, they are briefly discussed.
The hepatitis E virus (HEV) is a single-stranded RNA virus which is known as a major cause of acute viral hepatitis especially in developing countries through ingestion of contaminated water sources [18, 63]. While it generally causes a mild illness in most adults, pregnant women tend to have more severe disease. Mortality has been observed in pregnant women, especially if infected with genotype 1 [18, 63]. HEV is estimated to be responsible for up to 3000 stillbirths a year in developing countries and can commonly cause preterm delivery in infected mothers with resultant poor neonatal outcomes [63, 64]. When HEV is transmitted vertically, hepatitis can be present from birth and persist throughout the infant’s life but is not known to be associated with congenital anomalies.
Enteroviruses are a group of RNA viruses that can spread between humans via respiratory routes, vertically, and fecal-oral transmission [18]. Symptoms in adults and children can be varied and may include respiratory, dermatologic, neurologic, ocular, cardiac, muscular, and gastrointestinal manifestations [18]. When enterovirus is transmitted vertically or more commonly peripartum, the neonate may remain asymptomatic without sequelae or have severe symptoms including septic shock with multiorgan dysfunction [65]. There is limited evidence to suggest that infection with enterovirus during pregnancy is associated with congenital anomalies or fetal death [65].
Lymphocytic choriomeningitis virus (LCMV) is a single-stranded RNA virus spread by rodents which can cross the placenta; rarely it can be transmitted during delivery by exposure to maternal secretions or blood and cause congenital viral infection [66–68]. Infected pregnant women can have non-specific viral symptoms and may report direct exposure to or the presence of rodents in their homes [66, 68]. Common findings in an infant affected by LCMV are macrocephaly or microcephaly and ocular abnormalities; additionally, neurological abnormalities may be present and include hydrocephalus, periventricular calcifications, seizures, neurodevelopmental sequelae including intellectual disability, or even death [67, 68]. These symptoms suggest a similarity with other congenital infections previously discussed, such as CMV or toxoplasmosis, which may contribute to an underestimation of the prevalence of LCMV when congenital infection is suspected [66, 68].
The West Nile Virus (WNV) is a flavivirus that was initially isolated in 1937 and did not reach the United States until an outbreak in 1999 [69–71]. The primary mode of transmission is through the bite of an infected Culex species mosquito, with individuals ranging from no symptoms to 0.7% of infected individuals developing neuro-invasive disease with encephalitis, meningitis or acute flaccid paralysis possible [69]. There is no specific treatment or vaccine at this time [70]. Case reports of infants born to mothers with WNV have shown an array of outcomes, with follow up at 2–3 years of age not consistently showing any developmental delays [69]. Findings have included chorioretinitis, white-matter loss and cystic changes, and congenital defects such as lissencephaly, polydactyly, aortic coarctation and cleft palate [69]. Additional studies on the impact of infants with exposure during gestation, and longer-term outcomes are needed to truly delineate if WNV results in congenital anomalies.
Human adenoviruses (HAdV) are DNA viruses in the Adenoviridae family, with 7 subgroups and 52 serotypes [72]. While typically the cause of a “cold”, the severity of illness can range from mild to severe with gastroenteritis, pneumonia and neurologic disease possible [73]. Reports have not noted any specific fetal malformations, although infants with positive polymerase chain reaction (PCR) testing had a higher incidence of neural tube defects and echogenic liver lesions with and without hydrops [74].
Many of the maternal infections that previously resulted in significant impact and poor outcomes on the developing fetus have improved as treatments and vaccines have been introduced and refined. However, other pathogens are now becoming more apparent in their impact on fetal development, such as Zika virus. Some infections are declining in incidence, with a resultant decrease in congenital infections (such as the nearly 80% decline in Rubella infections) [51]. Other infections are continuing to increase, with the true impact on society yet to be determined. Thus, it is imperative that we monitor any infections in a pregnant woman, and complete a thorough examination and evaluation of each infant born with the hopes of identifying any abnormalities quickly and improving the outcomes of each infant to the best of our ability.
The Edited Volume, also known as the IntechOpen Book, is an IntechOpen pioneered publishing product. Edited Volumes make up the core of our business - and as pioneers and developers of this Open Access book publishing format, we have helped change the way scholars and scientists publish their scientific papers - as scientific chapters.
",metaTitle:"Edited Volumes",metaDescription:"The Edited Volume, also known as the InTechOpen Book, is an InTechOpen pioneered publishing product. Edited Volumes make up the core of our business - and as pioneers and developers of this Open Access book publishing format, we have helped change the way scholars and scientists publish their scientific papers - as scientific chapters. ",metaKeywords:null,canonicalURL:"/pages/edited-volumes",contentRaw:'[{"type":"htmlEditorComponent","content":"WHY PUBLISH IN AN INTECHOPEN EDITED VOLUME?
\\n\\nOut of all of the publishing options available to researchers, why choose to contribute your research to an IntechOpen Edited Volume? The reasons are simple. IntechOpen has worked exceptionally hard over the past years to fine tune the Open Access book publishing process and we continue to work hard to deliver the best for all of our contributors. The quality of published content is of utmost importance to us, followed closely by speed, and of course, availability and accessibility. To view current Open Access book projects that are Open for Submissions visit us here.
\\n\\nQUALITY CONTENT
\\n\\nOver the years we have learned what is important. What makes a difference to the researchers that work with us, what they value. Something that is very high not only on their lists, but our own, is the quality of the published content.
\\n\\nOur books contain scientific content written by two Nobel Prize winners, two Breakthrough Prize winners and 73 authors who are in the top 1% Most Cited.
\\n\\nWith regular submission for coverage in the single most important database, the Book Citation Index in the Web of Science™ Core Collection (BKCI), and no rejected submissions to date, over 43% of all Open Access books indexed in the BKCI are IntechOpen published books.
\\n\\nIn addition to BKCI, IntechOpen covers a number of important discipline specific databases as well, such as Thomson Reuters’ BIOSIS Previews.
\\n\\nACCESS
\\n\\nThe need for up to date information available at the click of a mouse is one thing that sets IntechOpen apart. By developing our own technologies in order to streamline the publishing process, we are able to minimize the amount of time from initial submission of a manuscript to its final publication date, without compromising the rigor of the editorial and peer review process. This means that the research published stays relevant, and in this fast paced world, this is very important.
\\n\\nYOUR WORK, YOUR COPYRIGHT
\\n\\nThe utilization of CC licenses allow researchers to retain copyright to their work. Researchers are free to use, adapt and share all content they publish with us. You will never have to pay permission fees to reuse a part of an experiment that you worked so hard to complete and are free to build upon your own research and the research of others. The Edited Volume helps bring together research from all over the world and compiles that research into one book - accessible for all. The research presented in chapter one can inspire the author of chapter three to take his or her research to the next level. It is about sharing ideas, insights and knowledge.
\\n\\nCan collaboration be inspired by a publishing format? At IntechOpen, the answer is yes. The way the research is published, the way it is accessed, it’s all part of our mission to help academics make a greater impact by giving readers free access to all published work.
\\n\\nOur Open Access book collection includes:
\\n\\n3,332 OPEN ACCESS BOOKS
\\n\\n107,564 INTERNATIONAL AUTHORS AND ACADEMIC EDITORS
\\n\\n113+ MILLION DOWNLOADS
\\n\\nPUBLISHING PROCESS STEPS
\\n\\nSee a complete overview of all publishing process steps and descriptions here.
\\n\\nCURRENT PROJECTS
\\n\\nTo view current Open Access book projects that are Open for Submissions visit us here.
\\n\\nNot sure if this is the right publishing option for you? Feel free to contact us at book.department@intechopen.com.
\\n"}]'},components:[{type:"htmlEditorComponent",content:'WHY PUBLISH IN AN INTECHOPEN EDITED VOLUME?
\n\nOut of all of the publishing options available to researchers, why choose to contribute your research to an IntechOpen Edited Volume? The reasons are simple. IntechOpen has worked exceptionally hard over the past years to fine tune the Open Access book publishing process and we continue to work hard to deliver the best for all of our contributors. The quality of published content is of utmost importance to us, followed closely by speed, and of course, availability and accessibility. To view current Open Access book projects that are Open for Submissions visit us here.
\n\nQUALITY CONTENT
\n\nOver the years we have learned what is important. What makes a difference to the researchers that work with us, what they value. Something that is very high not only on their lists, but our own, is the quality of the published content.
\n\nOur books contain scientific content written by two Nobel Prize winners, two Breakthrough Prize winners and 73 authors who are in the top 1% Most Cited.
\n\nWith regular submission for coverage in the single most important database, the Book Citation Index in the Web of Science™ Core Collection (BKCI), and no rejected submissions to date, over 43% of all Open Access books indexed in the BKCI are IntechOpen published books.
\n\nIn addition to BKCI, IntechOpen covers a number of important discipline specific databases as well, such as Thomson Reuters’ BIOSIS Previews.
\n\nACCESS
\n\nThe need for up to date information available at the click of a mouse is one thing that sets IntechOpen apart. By developing our own technologies in order to streamline the publishing process, we are able to minimize the amount of time from initial submission of a manuscript to its final publication date, without compromising the rigor of the editorial and peer review process. This means that the research published stays relevant, and in this fast paced world, this is very important.
\n\nYOUR WORK, YOUR COPYRIGHT
\n\nThe utilization of CC licenses allow researchers to retain copyright to their work. Researchers are free to use, adapt and share all content they publish with us. You will never have to pay permission fees to reuse a part of an experiment that you worked so hard to complete and are free to build upon your own research and the research of others. The Edited Volume helps bring together research from all over the world and compiles that research into one book - accessible for all. The research presented in chapter one can inspire the author of chapter three to take his or her research to the next level. It is about sharing ideas, insights and knowledge.
\n\nCan collaboration be inspired by a publishing format? At IntechOpen, the answer is yes. The way the research is published, the way it is accessed, it’s all part of our mission to help academics make a greater impact by giving readers free access to all published work.
\n\nOur Open Access book collection includes:
\n\n3,332 OPEN ACCESS BOOKS
\n\n107,564 INTERNATIONAL AUTHORS AND ACADEMIC EDITORS
\n\n113+ MILLION DOWNLOADS
\n\nPUBLISHING PROCESS STEPS
\n\nSee a complete overview of all publishing process steps and descriptions here.
\n\nCURRENT PROJECTS
\n\nTo view current Open Access book projects that are Open for Submissions visit us here.
\n\nNot sure if this is the right publishing option for you? Feel free to contact us at book.department@intechopen.com.
\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:"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:"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:"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"}}},{id:"83411",title:"Dr.",name:"Carmen",middleName:null,surname:"Feijoo",slug:"carmen-feijoo",fullName:"Carmen Feijoo",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:{name:"Andrés Bello University",country:{name:"Chile"}}},{id:"6495",title:"Dr.",name:"Daniel",middleName:null,surname:"Eberli",slug:"daniel-eberli",fullName:"Daniel Eberli",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/6495/images/1947_n.jpg",biography:"Daniel Eberli MD. Ph.D. is a scientific physician working in the translational field of urologic tissue engineering. He has a medical degree from the Medical School in Zurich, Switzerland, and a Ph.D. in Molecular Medicine from Wake Forest University, Winston Salem, NC. He currently has a faculty position at the Department of Urology at the University Hospital Zurich, where he devotes half of his time to patient care. He is a lecturer at the Medical School of Zurich and the Swiss Federal Institute of Technology. Together with his research team, he is working on novel biomaterials for bladder reconstruction, improving autonomic innervation, cellular treatment of incontinence and tracking of stem cells.",institutionString:null,institution:{name:"University Hospital of Zurich",country:{name:"Switzerland"}}},{id:"122240",title:"Prof.",name:"Frede",middleName:null,surname:"Blaabjerg",slug:"frede-blaabjerg",fullName:"Frede Blaabjerg",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:{name:"Aalborg University",country:{name:"Denmark"}}},{id:"50823",title:"Prof.",name:"Hamid Reza",middleName:null,surname:"Karimi",slug:"hamid-reza-karimi",fullName:"Hamid Reza Karimi",position:null,profilePictureURL:"//cdnintech.com/web/frontend/www/assets/author.svg",biography:null,institutionString:null,institution:{name:"Polytechnic University of Milan",country:{name:"Italy"}}},{id:"22128",title:"Dr.",name:"Harald",middleName:null,surname:"Haas",slug:"harald-haas",fullName:"Harald Haas",position:null,profilePictureURL:"https://mts.intechopen.com/storage/users/no_image.jpg",biography:null,institutionString:null,institution:{name:"University of Edinburgh",country:{name:"United Kingdom"}}}],filtersByRegion:[{group:"region",caption:"North America",value:1,count:5703},{group:"region",caption:"Middle and South America",value:2,count:5174},{group:"region",caption:"Africa",value:3,count:1690},{group:"region",caption:"Asia",value:4,count:10246},{group:"region",caption:"Australia and Oceania",value:5,count:889},{group:"region",caption:"Europe",value:6,count:15653}],offset:12,limit:12,total:20827},chapterEmbeded:{data:{}},editorApplication:{success:null,errors:{}},ofsBooks:{filterParams:{hasNoEditors:"0",sort:"dateEndThirdStepPublish",topicId:"23"},books:[{type:"book",id:"9538",title:"Demographic Analysis - Selected Concepts, Tools, and Applications",subtitle:null,isOpenForSubmission:!0,hash:"f335c5d0a39e8631d8627546e14ce61f",slug:null,bookSignature:"Ph.D. Andrzej Klimczuk",coverURL:"https://cdn.intechopen.com/books/images_new/9538.jpg",editedByType:null,editors:[{id:"320017",title:"Ph.D.",name:"Andrzej",surname:"Klimczuk",slug:"andrzej-klimczuk",fullName:"Andrzej Klimczuk"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10811",title:"Urban Transition - Perspectives on Urban Systems and Environments",subtitle:null,isOpenForSubmission:!0,hash:"4885cfa30ba6184b0da9f575aee65998",slug:null,bookSignature:"Ph.D. Marita Wallhagen and Dr. Mathias Cehlin",coverURL:"https://cdn.intechopen.com/books/images_new/10811.jpg",editedByType:null,editors:[{id:"337569",title:"Ph.D.",name:"Marita",surname:"Wallhagen",slug:"marita-wallhagen",fullName:"Marita Wallhagen"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10207",title:"Sexual Abuse - an Interdisciplinary Approach",subtitle:null,isOpenForSubmission:!0,hash:"e1ec1d5a7093490df314d7887e0b3809",slug:null,bookSignature:"Dr. Ersi Abaci Kalfoglou and Dr. Sotirios Kalfoglou",coverURL:"https://cdn.intechopen.com/books/images_new/10207.jpg",editedByType:null,editors:[{id:"68678",title:"Dr.",name:"Ersi Abaci",surname:"Kalfoglou",slug:"ersi-abaci-kalfoglou",fullName:"Ersi Abaci Kalfoglou"}],productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}],filtersByTopic:[{group:"topic",caption:"Agricultural and Biological Sciences",value:5,count:9},{group:"topic",caption:"Biochemistry, Genetics and Molecular Biology",value:6,count:14},{group:"topic",caption:"Business, Management and Economics",value:7,count:2},{group:"topic",caption:"Chemistry",value:8,count:6},{group:"topic",caption:"Computer and Information Science",value:9,count:10},{group:"topic",caption:"Earth and Planetary Sciences",value:10,count:4},{group:"topic",caption:"Engineering",value:11,count:16},{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:57},{group:"topic",caption:"Neuroscience",value:18,count:1},{group:"topic",caption:"Pharmacology, Toxicology and Pharmaceutical Science",value:19,count:5},{group:"topic",caption:"Physics",value:20,count:2},{group:"topic",caption:"Psychology",value:21,count:3},{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:2}],offset:12,limit:12,total:3},popularBooks:{featuredBooks:[{type:"book",id:"7802",title:"Modern Slavery and Human Trafficking",subtitle:null,isOpenForSubmission:!1,hash:"587a0b7fb765f31cc98de33c6c07c2e0",slug:"modern-slavery-and-human-trafficking",bookSignature:"Jane Reeves",coverURL:"https://cdn.intechopen.com/books/images_new/7802.jpg",editors:[{id:"211328",title:"Prof.",name:"Jane",middleName:null,surname:"Reeves",slug:"jane-reeves",fullName:"Jane Reeves"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9961",title:"Data Mining",subtitle:"Methods, Applications and Systems",isOpenForSubmission:!1,hash:"ed79fb6364f2caf464079f94a0387146",slug:"data-mining-methods-applications-and-systems",bookSignature:"Derya Birant",coverURL:"https://cdn.intechopen.com/books/images_new/9961.jpg",editors:[{id:"15609",title:"Dr.",name:"Derya",middleName:null,surname:"Birant",slug:"derya-birant",fullName:"Derya Birant"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8545",title:"Animal Reproduction in Veterinary Medicine",subtitle:null,isOpenForSubmission:!1,hash:"13aaddf5fdbbc78387e77a7da2388bf6",slug:"animal-reproduction-in-veterinary-medicine",bookSignature:"Faruk Aral, Rita Payan-Carreira and Miguel Quaresma",coverURL:"https://cdn.intechopen.com/books/images_new/8545.jpg",editors:[{id:"25600",title:"Prof.",name:"Faruk",middleName:null,surname:"Aral",slug:"faruk-aral",fullName:"Faruk Aral"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9157",title:"Neurodegenerative Diseases",subtitle:"Molecular Mechanisms and Current Therapeutic Approaches",isOpenForSubmission:!1,hash:"bc8be577966ef88735677d7e1e92ed28",slug:"neurodegenerative-diseases-molecular-mechanisms-and-current-therapeutic-approaches",bookSignature:"Nagehan Ersoy Tunalı",coverURL:"https://cdn.intechopen.com/books/images_new/9157.jpg",editors:[{id:"82778",title:"Ph.D.",name:"Nagehan",middleName:null,surname:"Ersoy Tunalı",slug:"nagehan-ersoy-tunali",fullName:"Nagehan Ersoy Tunalı"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8686",title:"Direct Torque Control Strategies of Electrical Machines",subtitle:null,isOpenForSubmission:!1,hash:"b6ad22b14db2b8450228545d3d4f6b1a",slug:"direct-torque-control-strategies-of-electrical-machines",bookSignature:"Fatma Ben Salem",coverURL:"https://cdn.intechopen.com/books/images_new/8686.jpg",editors:[{id:"295623",title:"Associate Prof.",name:"Fatma",middleName:null,surname:"Ben Salem",slug:"fatma-ben-salem",fullName:"Fatma Ben Salem"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7434",title:"Molecular Biotechnology",subtitle:null,isOpenForSubmission:!1,hash:"eceede809920e1ec7ecadd4691ede2ec",slug:"molecular-biotechnology",bookSignature:"Sergey Sedykh",coverURL:"https://cdn.intechopen.com/books/images_new/7434.jpg",editors:[{id:"178316",title:"Ph.D.",name:"Sergey",middleName:null,surname:"Sedykh",slug:"sergey-sedykh",fullName:"Sergey Sedykh"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9208",title:"Welding",subtitle:"Modern Topics",isOpenForSubmission:!1,hash:"7d6be076ccf3a3f8bd2ca52d86d4506b",slug:"welding-modern-topics",bookSignature:"Sadek Crisóstomo Absi Alfaro, Wojciech Borek and Błażej Tomiczek",coverURL:"https://cdn.intechopen.com/books/images_new/9208.jpg",editors:[{id:"65292",title:"Prof.",name:"Sadek Crisostomo Absi",middleName:"C. Absi",surname:"Alfaro",slug:"sadek-crisostomo-absi-alfaro",fullName:"Sadek Crisostomo Absi Alfaro"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7831",title:"Sustainability in Urban Planning and Design",subtitle:null,isOpenForSubmission:!1,hash:"c924420492c8c2c9751e178d025f4066",slug:"sustainability-in-urban-planning-and-design",bookSignature:"Amjad Almusaed, Asaad Almssad and Linh Truong - Hong",coverURL:"https://cdn.intechopen.com/books/images_new/7831.jpg",editors:[{id:"110471",title:"Dr.",name:"Amjad",middleName:"Zaki",surname:"Almusaed",slug:"amjad-almusaed",fullName:"Amjad Almusaed"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9343",title:"Trace Metals in the Environment",subtitle:"New Approaches and Recent Advances",isOpenForSubmission:!1,hash:"ae07e345bc2ce1ebbda9f70c5cd12141",slug:"trace-metals-in-the-environment-new-approaches-and-recent-advances",bookSignature:"Mario Alfonso Murillo-Tovar, Hugo Saldarriaga-Noreña and Agnieszka Saeid",coverURL:"https://cdn.intechopen.com/books/images_new/9343.jpg",editors:[{id:"255959",title:"Dr.",name:"Mario Alfonso",middleName:null,surname:"Murillo-Tovar",slug:"mario-alfonso-murillo-tovar",fullName:"Mario Alfonso Murillo-Tovar"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9139",title:"Topics in Primary Care Medicine",subtitle:null,isOpenForSubmission:!1,hash:"ea774a4d4c1179da92a782e0ae9cde92",slug:"topics-in-primary-care-medicine",bookSignature:"Thomas F. Heston",coverURL:"https://cdn.intechopen.com/books/images_new/9139.jpg",editors:[{id:"217926",title:"Dr.",name:"Thomas F.",middleName:null,surname:"Heston",slug:"thomas-f.-heston",fullName:"Thomas F. Heston"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9839",title:"Outdoor Recreation",subtitle:"Physiological and Psychological Effects on Health",isOpenForSubmission:!1,hash:"5f5a0d64267e32567daffa5b0c6a6972",slug:"outdoor-recreation-physiological-and-psychological-effects-on-health",bookSignature:"Hilde G. Nielsen",coverURL:"https://cdn.intechopen.com/books/images_new/9839.jpg",editors:[{id:"158692",title:"Ph.D.",name:"Hilde G.",middleName:null,surname:"Nielsen",slug:"hilde-g.-nielsen",fullName:"Hilde G. Nielsen"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8697",title:"Virtual Reality and Its Application in Education",subtitle:null,isOpenForSubmission:!1,hash:"ee01b5e387ba0062c6b0d1e9227bda05",slug:"virtual-reality-and-its-application-in-education",bookSignature:"Dragan Cvetković",coverURL:"https://cdn.intechopen.com/books/images_new/8697.jpg",editors:[{id:"101330",title:"Dr.",name:"Dragan",middleName:"Mladen",surname:"Cvetković",slug:"dragan-cvetkovic",fullName:"Dragan Cvetković"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}}],offset:12,limit:12,total:5146},hotBookTopics:{hotBooks:[],offset:0,limit:12,total:null},publish:{},publishingProposal:{success:null,errors:{}},books:{featuredBooks:[{type:"book",id:"7802",title:"Modern Slavery and Human Trafficking",subtitle:null,isOpenForSubmission:!1,hash:"587a0b7fb765f31cc98de33c6c07c2e0",slug:"modern-slavery-and-human-trafficking",bookSignature:"Jane Reeves",coverURL:"https://cdn.intechopen.com/books/images_new/7802.jpg",editors:[{id:"211328",title:"Prof.",name:"Jane",middleName:null,surname:"Reeves",slug:"jane-reeves",fullName:"Jane Reeves"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9961",title:"Data Mining",subtitle:"Methods, Applications and Systems",isOpenForSubmission:!1,hash:"ed79fb6364f2caf464079f94a0387146",slug:"data-mining-methods-applications-and-systems",bookSignature:"Derya Birant",coverURL:"https://cdn.intechopen.com/books/images_new/9961.jpg",editors:[{id:"15609",title:"Dr.",name:"Derya",middleName:null,surname:"Birant",slug:"derya-birant",fullName:"Derya Birant"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8545",title:"Animal Reproduction in Veterinary Medicine",subtitle:null,isOpenForSubmission:!1,hash:"13aaddf5fdbbc78387e77a7da2388bf6",slug:"animal-reproduction-in-veterinary-medicine",bookSignature:"Faruk Aral, Rita Payan-Carreira and Miguel Quaresma",coverURL:"https://cdn.intechopen.com/books/images_new/8545.jpg",editors:[{id:"25600",title:"Prof.",name:"Faruk",middleName:null,surname:"Aral",slug:"faruk-aral",fullName:"Faruk Aral"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9157",title:"Neurodegenerative Diseases",subtitle:"Molecular Mechanisms and Current Therapeutic Approaches",isOpenForSubmission:!1,hash:"bc8be577966ef88735677d7e1e92ed28",slug:"neurodegenerative-diseases-molecular-mechanisms-and-current-therapeutic-approaches",bookSignature:"Nagehan Ersoy Tunalı",coverURL:"https://cdn.intechopen.com/books/images_new/9157.jpg",editors:[{id:"82778",title:"Ph.D.",name:"Nagehan",middleName:null,surname:"Ersoy Tunalı",slug:"nagehan-ersoy-tunali",fullName:"Nagehan Ersoy Tunalı"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"8686",title:"Direct Torque Control Strategies of Electrical Machines",subtitle:null,isOpenForSubmission:!1,hash:"b6ad22b14db2b8450228545d3d4f6b1a",slug:"direct-torque-control-strategies-of-electrical-machines",bookSignature:"Fatma Ben Salem",coverURL:"https://cdn.intechopen.com/books/images_new/8686.jpg",editors:[{id:"295623",title:"Associate Prof.",name:"Fatma",middleName:null,surname:"Ben Salem",slug:"fatma-ben-salem",fullName:"Fatma Ben Salem"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7434",title:"Molecular Biotechnology",subtitle:null,isOpenForSubmission:!1,hash:"eceede809920e1ec7ecadd4691ede2ec",slug:"molecular-biotechnology",bookSignature:"Sergey Sedykh",coverURL:"https://cdn.intechopen.com/books/images_new/7434.jpg",editors:[{id:"178316",title:"Ph.D.",name:"Sergey",middleName:null,surname:"Sedykh",slug:"sergey-sedykh",fullName:"Sergey Sedykh"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9208",title:"Welding",subtitle:"Modern Topics",isOpenForSubmission:!1,hash:"7d6be076ccf3a3f8bd2ca52d86d4506b",slug:"welding-modern-topics",bookSignature:"Sadek Crisóstomo Absi Alfaro, Wojciech Borek and Błażej Tomiczek",coverURL:"https://cdn.intechopen.com/books/images_new/9208.jpg",editors:[{id:"65292",title:"Prof.",name:"Sadek Crisostomo Absi",middleName:"C. Absi",surname:"Alfaro",slug:"sadek-crisostomo-absi-alfaro",fullName:"Sadek Crisostomo Absi Alfaro"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"7831",title:"Sustainability in Urban Planning and Design",subtitle:null,isOpenForSubmission:!1,hash:"c924420492c8c2c9751e178d025f4066",slug:"sustainability-in-urban-planning-and-design",bookSignature:"Amjad Almusaed, Asaad Almssad and Linh Truong - Hong",coverURL:"https://cdn.intechopen.com/books/images_new/7831.jpg",editors:[{id:"110471",title:"Dr.",name:"Amjad",middleName:"Zaki",surname:"Almusaed",slug:"amjad-almusaed",fullName:"Amjad Almusaed"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9343",title:"Trace Metals in the Environment",subtitle:"New Approaches and Recent Advances",isOpenForSubmission:!1,hash:"ae07e345bc2ce1ebbda9f70c5cd12141",slug:"trace-metals-in-the-environment-new-approaches-and-recent-advances",bookSignature:"Mario Alfonso Murillo-Tovar, Hugo Saldarriaga-Noreña and Agnieszka Saeid",coverURL:"https://cdn.intechopen.com/books/images_new/9343.jpg",editors:[{id:"255959",title:"Dr.",name:"Mario Alfonso",middleName:null,surname:"Murillo-Tovar",slug:"mario-alfonso-murillo-tovar",fullName:"Mario Alfonso Murillo-Tovar"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}},{type:"book",id:"9139",title:"Topics in Primary Care Medicine",subtitle:null,isOpenForSubmission:!1,hash:"ea774a4d4c1179da92a782e0ae9cde92",slug:"topics-in-primary-care-medicine",bookSignature:"Thomas F. Heston",coverURL:"https://cdn.intechopen.com/books/images_new/9139.jpg",editors:[{id:"217926",title:"Dr.",name:"Thomas F.",middleName:null,surname:"Heston",slug:"thomas-f.-heston",fullName:"Thomas F. Heston"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter"}}],latestBooks:[{type:"book",id:"7434",title:"Molecular Biotechnology",subtitle:null,isOpenForSubmission:!1,hash:"eceede809920e1ec7ecadd4691ede2ec",slug:"molecular-biotechnology",bookSignature:"Sergey Sedykh",coverURL:"https://cdn.intechopen.com/books/images_new/7434.jpg",editedByType:"Edited by",editors:[{id:"178316",title:"Ph.D.",name:"Sergey",middleName:null,surname:"Sedykh",slug:"sergey-sedykh",fullName:"Sergey Sedykh"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8545",title:"Animal Reproduction in Veterinary Medicine",subtitle:null,isOpenForSubmission:!1,hash:"13aaddf5fdbbc78387e77a7da2388bf6",slug:"animal-reproduction-in-veterinary-medicine",bookSignature:"Faruk Aral, Rita Payan-Carreira and Miguel Quaresma",coverURL:"https://cdn.intechopen.com/books/images_new/8545.jpg",editedByType:"Edited by",editors:[{id:"25600",title:"Prof.",name:"Faruk",middleName:null,surname:"Aral",slug:"faruk-aral",fullName:"Faruk Aral"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9569",title:"Methods in Molecular Medicine",subtitle:null,isOpenForSubmission:!1,hash:"691d3f3c4ac25a8093414e9b270d2843",slug:"methods-in-molecular-medicine",bookSignature:"Yusuf Tutar",coverURL:"https://cdn.intechopen.com/books/images_new/9569.jpg",editedByType:"Edited by",editors:[{id:"158492",title:"Prof.",name:"Yusuf",middleName:null,surname:"Tutar",slug:"yusuf-tutar",fullName:"Yusuf Tutar"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9839",title:"Outdoor Recreation",subtitle:"Physiological and Psychological Effects on Health",isOpenForSubmission:!1,hash:"5f5a0d64267e32567daffa5b0c6a6972",slug:"outdoor-recreation-physiological-and-psychological-effects-on-health",bookSignature:"Hilde G. Nielsen",coverURL:"https://cdn.intechopen.com/books/images_new/9839.jpg",editedByType:"Edited by",editors:[{id:"158692",title:"Ph.D.",name:"Hilde G.",middleName:null,surname:"Nielsen",slug:"hilde-g.-nielsen",fullName:"Hilde G. Nielsen"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"7802",title:"Modern Slavery and Human Trafficking",subtitle:null,isOpenForSubmission:!1,hash:"587a0b7fb765f31cc98de33c6c07c2e0",slug:"modern-slavery-and-human-trafficking",bookSignature:"Jane Reeves",coverURL:"https://cdn.intechopen.com/books/images_new/7802.jpg",editedByType:"Edited by",editors:[{id:"211328",title:"Prof.",name:"Jane",middleName:null,surname:"Reeves",slug:"jane-reeves",fullName:"Jane Reeves"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8063",title:"Food Security in Africa",subtitle:null,isOpenForSubmission:!1,hash:"8cbf3d662b104d19db2efc9d59249efc",slug:"food-security-in-africa",bookSignature:"Barakat Mahmoud",coverURL:"https://cdn.intechopen.com/books/images_new/8063.jpg",editedByType:"Edited by",editors:[{id:"92016",title:"Dr.",name:"Barakat",middleName:null,surname:"Mahmoud",slug:"barakat-mahmoud",fullName:"Barakat Mahmoud"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"10118",title:"Plant Stress Physiology",subtitle:null,isOpenForSubmission:!1,hash:"c68b09d2d2634fc719ae3b9a64a27839",slug:"plant-stress-physiology",bookSignature:"Akbar Hossain",coverURL:"https://cdn.intechopen.com/books/images_new/10118.jpg",editedByType:"Edited by",editors:[{id:"280755",title:"Dr.",name:"Akbar",middleName:null,surname:"Hossain",slug:"akbar-hossain",fullName:"Akbar Hossain"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9157",title:"Neurodegenerative Diseases",subtitle:"Molecular Mechanisms and Current Therapeutic Approaches",isOpenForSubmission:!1,hash:"bc8be577966ef88735677d7e1e92ed28",slug:"neurodegenerative-diseases-molecular-mechanisms-and-current-therapeutic-approaches",bookSignature:"Nagehan Ersoy Tunalı",coverURL:"https://cdn.intechopen.com/books/images_new/9157.jpg",editedByType:"Edited by",editors:[{id:"82778",title:"Ph.D.",name:"Nagehan",middleName:null,surname:"Ersoy Tunalı",slug:"nagehan-ersoy-tunali",fullName:"Nagehan Ersoy Tunalı"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"9961",title:"Data Mining",subtitle:"Methods, Applications and Systems",isOpenForSubmission:!1,hash:"ed79fb6364f2caf464079f94a0387146",slug:"data-mining-methods-applications-and-systems",bookSignature:"Derya Birant",coverURL:"https://cdn.intechopen.com/books/images_new/9961.jpg",editedByType:"Edited by",editors:[{id:"15609",title:"Dr.",name:"Derya",middleName:null,surname:"Birant",slug:"derya-birant",fullName:"Derya Birant"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}},{type:"book",id:"8686",title:"Direct Torque Control Strategies of Electrical Machines",subtitle:null,isOpenForSubmission:!1,hash:"b6ad22b14db2b8450228545d3d4f6b1a",slug:"direct-torque-control-strategies-of-electrical-machines",bookSignature:"Fatma Ben Salem",coverURL:"https://cdn.intechopen.com/books/images_new/8686.jpg",editedByType:"Edited by",editors:[{id:"295623",title:"Associate Prof.",name:"Fatma",middleName:null,surname:"Ben Salem",slug:"fatma-ben-salem",fullName:"Fatma Ben Salem"}],equalEditorOne:null,equalEditorTwo:null,equalEditorThree:null,productType:{id:"1",chapterContentType:"chapter",authoredCaption:"Edited by"}}]},subject:{topic:{id:"910",title:"Protozoology",slug:"protozoology",parent:{title:"Pure Microbiology",slug:"pure-microbiology"},numberOfBooks:0,numberOfAuthorsAndEditors:0,numberOfWosCitations:0,numberOfCrossrefCitations:0,numberOfDimensionsCitations:0,videoUrl:null,fallbackUrl:null,description:null},booksByTopicFilter:{topicSlug:"protozoology",sort:"-publishedDate",limit:12,offset:0},booksByTopicCollection:[],booksByTopicTotal:0,mostCitedChapters:[],mostDownloadedChaptersLast30Days:[],onlineFirstChaptersFilter:{topicSlug:"protozoology",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:"profile.detail",path:"/profiles/118191/hiroyuki-yoneyama",hash:"",query:{},params:{id:"118191",slug:"hiroyuki-yoneyama"},fullPath:"/profiles/118191/hiroyuki-yoneyama",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)}()