Chapters authored
Applications of Fiber Optic Coupled-Grazing Angle Probe Reflection-Absorption FTIR Spectroscopy
Part of the book: Fourier Transforms
Applications of Optical Fibers to Spectroscopy: Detection of High Explosives and Other Threat Chemicals
Part of the book: Selected Topics on Optical Fiber Technology
Multivariate Analysis in Vibrational Spectroscopy of Highly Energetic Materials and Chemical Warfare Agents Simulants
Part of the book: Multivariate Analysis in Management, Engineering and the Sciences
Mid-Infrared Laser Spectroscopy Applications in Process Analytical Technology: Cleaning Validation, Microorganisms, and Active Pharmaceutical Ingredients in Formulations
Mid-infrared (MIR) lasers are very high-brightness energy sources that are replacing conventional thermal sources (globars) in many infrared spectroscopy (IRS) techniques. Although not all laser properties have been exploited in depth, properties such as collimation, polarization, high brightness, and very high resolution have contributed to recast IRS tools. Applications of MIR laser spectroscopy to process analytical technology (PAT) are numerous and important. As an example, a compact grazing angle probe mount has allowed coupling to a MIR quantum cascade laser (QCL), enabling reflectance-absorbance infrared spectroscopy (RAIRS) measurements. This methodology, coupled to powerful multivariable analysis (MVA) routines of chemometrics and fast Fourier transform (FFT) preprocessing of the data resulted in very low limits of detection of active pharmaceutical ingredients (APIs) and high explosives (HEs) reaching trace levels. This methodology can be used to measure concentrations of surface contaminants for validation of cleanliness of pharmaceutical and biotechnology processing batch reactors and other manufacturing vessels. Another application discussed concerns the enhanced detection of microorganisms that can be encountered in pharmaceutical and biotechnology plants as contaminants and that could also be used as weapons of mass destruction in biological warfare. In the last application discussed, the concentration of APIs in formulations was determined by MIR laser spectroscopy and was cross validated with high-performance liquid chromatography.
Part of the book: Infrared Spectroscopy
Mid-Infrared Laser Spectroscopy Applications I: Detection of Traces of High Explosives on Reflective and Matte Substrates
Mid-infrared (MIR) lasers have revolutionized infrared vibrational spectroscopy, converting an already dominant spectroscopic analysis technique into an even more powerful, easier to use, and quicker turn-around cadre of versatile spectroscopic tools. A selection of applications, revisited under the umbrella of MIR laser-based properties, very high brightness, collimated beams, polarized sources, highly monochromatic tunable sources, and coherent sources, is included. Applications discussed concern enhanced detection, discrimination, and quantification of high explosives (HEs). From reflectance measurements of chemical residues on highly reflective metallic substrates to reflectance measurements of HEs deposited on non-reflective, matte substrates is discussed. Coupling with multivariate analyses (MVA) techniques of Chemometrics allowed near trace detection of HEs, with sharp discrimination from highly MIR absorbing substrates.
Part of the book: Infrared Spectroscopy
Inhibition of Protein Fibrillation by Hydrogen Sulfide1
View all chaptersAmyloid fibrils are misfolded proteins, which are often associated with various neurodegenerative diseases such as Alzheimer’s. The amount of hydrogen sulfide (H2S) is known to be reduced in the brain tissue of people diagnosed with Alzheimer’s disease relative to that of healthy individuals. Hen Egg-White Lysozyme (HEWL) forms typical β-sheet-rich fibrils during 70 minutes at low pH and high temperatures. These results are consistent with the ThT findings that β-sheets structure is also present in myoglobin (Mb), and hemoglobin (Hb) in the presence of 45% TFE. The addition of H2S in the process completely inhibits the formation of amyloid fibrils in HEWL, Mb, and Hb as revealed by several spectroscopic techniques. Non-resonance Raman bands corresponding to disulfide (RSSR) vibrational modes in the 550-500 cm-1 spectral range decreases in intensity and is accompanied by the appearance of a new 490 cm-1 band assigned to the trisulfide group (RSSSR). Intrinsic tryptophan fluorescence shows a partial denaturation of HEWL containing trisulfide bonds. Overall, the Mb and Hb result ties excellent with the HEWL data showing that the presence of H2S during these proteins fibrillation processes protects the α-helical protein structures, preventing the formation of amyloids in these different proteins moieties.
Part of the book: Amyloid Diseases