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Fourier transform infrared (FTIR) and Fourier transform nuclear magnetic resonance (FTNMR) methods were used to examine the adsorption and reaction of diisopropyl fluorophosphate (DFP) on various solid adsorbents. Static and flow system experiments were monitored using FTIR to determine DFP adsorption rates and isotherms on silica, coated silicas, gamma-alumina, coated aluminas, and activated charcoal. The adsorption of DFP(g) onto the solid adsorbents was generally very rapid, with a half-life of 20 seconds for 1 mg DFP onto 25 mg of 350 sq. m/g silica. The DFP adsorption isotherm on silica indicated chemi-sorption to a monolayer at P/Po 0.6, followed by increased coverage that appears to be physical adsorption. Diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy, photoacoustic spectroscopy (PAS), and solid state 31P NMR of adsorbed DFP showed chemisorption on silica and on alumina. Bonding at the P=O of DFP was indicated by a -41/cm shift in the NU(P=O) and a 1 ppm upfield shift in the 31 P resonance.

The utility of infrared analysis for industrial applications has increased due to the availability of Fourier transform infrared (FT-IR) spectrometers. This increase has come about because of the advantages that FT-IR offers over other types of infrared equipment. These advantages include speed of analysis, good wavelength stability, high energy throughput, and high sensitivity. The above factors coupled with PC control, easy to use software; small footprint and relatively low purchase cost have made modern FT-IR systems a more powerful and cost effective analytical tool. Application of this tool to maintenance management is reaching new heights because of the many facets of maintenance quality assurance to which infrared analysis can be applied. It is through a better understanding of the capabilities of FT-IR analysis to solve maintenance management problems that its use will continue to grow.

Drought isa major constraint in many rainfed areas and affects rice yield. We aimed to characterize the physiological changes in rice in response to drought using Fourier transform infrared (FTIR) spectroscopy. Eighty rice landrace seedlings were subjected to drought in the greenhouse using a PEG 6000. Physiological parameters, including total chlorophyll content, relative water content, electrolyte leakage, and biochemical changes were evaluated. Based on the FTIR results, the landraces were divided into three main groups: tolerant, moderately tolerant, and susceptible. Principal component analysis revealed spectral differences between the control and drought stress treatment groups. Lipid, pectin, and lignin content increased after drought stress. The biochemical components of plants at different drought tolerance levels were also compared. The lipid (CH 2 and CH 3 ), lignin (C=C), pectin (C=O), and protein (C=O, N–H) contents were the highest in the drought-tolerant cultivars, followed by the moderately tolerant and susceptible cultivars, respectively. Cultivar 17 and 49 were the most tolerant, and the functional groups were identified and characterized using FTIR. Overall, these results will be useful in selecting parental cultivars for rice breeding programs.

Drought isa major constraint in many rainfed areas and affects rice yield. We aimed to characterize the physiological changes in rice in response to drought using Fourier transform infrared (FTIR) spectroscopy. Eighty rice landrace seedlings were subjected to drought in the greenhouse using a PEG 6000. Physiological parameters, including total chlorophyll content, relative water content, electrolyte leakage, and biochemical changes were evaluated. Based on the FTIR results, the landraces were divided into three main groups: tolerant, moderately tolerant, and susceptible. Principal component analysis revealed spectral differences between the control and drought stress treatment groups. Lipid, pectin, and lignin content increased after drought stress. The biochemical components of plants at different drought tolerance levels were also compared. The lipid (CH 2 and CH 3 ), lignin (C=C), pectin (C=O), and protein (C=O, N–H) contents were the highest in the drought-tolerant cultivars, followed by the moderately tolerant and susceptible cultivars, respectively. Cultivar 17 and 49 were the most tolerant, and the functional groups were identified and characterized using FTIR. Overall, these results will be useful in selecting parental cultivars for rice breeding programs.

A balloon-borne liquid nitrogen cooled Fourier transform spectrometer system was test-flown from Holloman Air Force Base on 8 October 1980. The system and the modifications to it required for balloon application are described and the flight results discussed. Samples of the interferograms obtained during the flight and their transforms are presented. Procedures for improving the performance on subsequent flights are discussed. (Author)

This article is from PLoS ONE , volume 9 . Abstract The present study was designed to investigate the potential of Fourier transform infrared (FT-IR) spectroscopy to identify Trueperella (T.) pyogenes isolated from bovine clinical mastitis. FT-IR spectroscopy was applied to 57 isolates obtained from 55 cows in a period from 2009 to 2012. Prior to FT-IR spectroscopy these isolates were identified by phenotypic and genotypic properties, also including the determination of seven potential virulence factor encoding genes. The FT-IR analysis revealed a reliable identification of all 57 isolates as T. pyogenes and a clear separation of this species from the other species of genus Trueperella and from species of genus Arcanobacterium and Actinomyces. The results showed that all 57 isolates were assigned to the correct species indicating that FT-IR spectroscopy could also be efficiently used for identification of this bacterial pathogen.

Counterfeit and illicit tobacco may contain potentially toxic organic impurities that result in adverse health effects for the consumer. Carcinogenic substances have been found in elevated concentrations in counterfeit tobacco. The current study explored swift and cost-effective methods, such as Fourier-transform infrared, Raman, and near-infrared spectroscopy to identify counterfeit tobacco products. Moreover, it also assessed the spectral quality based on range, number of peaks, maximum peak intensity, and signal-to-noise ratio. In spectral analysis, infrared exhibited superior quality over Raman and near-infrared with a higher signal-to-noise ratio. Near-infrared, although with a limited wavelength range, showed good quality. Raman, however, displayed poor spectral quality due to noise interference. Identification success varied with chemo metric methods, with infrared correctly identifying four out of five counterfeit tobacco products and near-infrared identifying three out of five. Raman failed in identification, while infrared showed success with some mismatches using principal component analysis. Near-infrared and Raman successfully identified counterfeit tobacco, with near-infrared providing the most distinct separation. Quantification results varied across spectroscopy techniques and chemo-metric methods. 

A Pt/SnO2 catalyst has been developed at NASA Langley that is effective for the oxidation of CO at room temperature (1). A mechanism has been proposed to explain the effectiveness of this catalyst (2), but most of the species involved in this mechanism have not been observed under actual catalytic conditions. A number of these species are potentially detectable by Fourier Transform Infrared Spectroscopy (FTIR), e.g., HOSnO sub x, HO sub y PtO sub z, Pt-CO, and SnHCO3. Therefore a preliminary investigation was conducted to determine what might be learned about this particular catalyst by transmission FTIR. The main advantage of FTIR for this work is that the catalyst can be examined under conditions similar to the actual catalytic conditions. This can be of critical importance since some surface species may exist only when the reaction gases are present. Another advantage of the infrared approach is that since vibrations are probed, subtle chemical details may be obtained. The main disadvantage of this approach is that FTIR is not nearly as sensitive as the Ultra High Vacuum (UHV) surface analytical techniques such as Auger, Electron Spectroscopy for Chemical Analysis (ESCA), Electron Energy Loss Spectroscopy (EELS), etc. Another problem is that the assignment of the observed infrared bands may be difficult.

A balloon-borne liquid nitrogen cooled Fourier transform spectrometer system was test-flown from Holloman Air Force Base on 8 October 1980. The system and the modifications to it required for balloon application are described and the flight results discussed. Samples of the interferograms obtained during the flight and their transforms are presented. Procedures for improving the performance on subsequent flights are discussed. (Author)

A data collection sensor based on a Bomem Fourier transform spectrometer was used to measure infrared multispectral target/background signatures. This report describes the data collection sensor, including data processing software for quick look data analysis, gives the sensor characteristics test procedures and their results, and analyzes the effect of the sensor characteristics on the quality of the measured signatures.The sensor gives a very high level of performance including noise equivalent spectral radiances of 1 nW/sq cm sr cm-1 in the MWIR (3 to 5 micrometers) region and 6 nW/sq cm sr cm-1 in the LWIR (8 to 12 micrometers region), a relative calibration accuracy to less than 0.25% above 4 micrometers, and spectral band-to-band correlation preservation greater than 0.9999 in the LWIR, and greater than 0.9995 between MWIR and LwIR and within the 4 to 5 micrometers region of the MWIR.

Polarization modulated Fourier transform infrared reflection absorption spectroscopy (FT-IR-RAS) is used to study the interphase between polycrystalline gold electrodes and 0.5 M K2SO4 solution as a function of potential and CN(-) concentration. Surface cyanide species, adsorbed on the gold electrode, give rise to a C-N stretching band at 2105/cm at -1.0V (Ag/AgC1) which undergoes a shift of approximately 30/cm/V to higher wavenumber at more positive potentials. The species is identified as linearly adsorbed CN(-) ions. The Au(CN)2- complex, which gives rise to a C-N stretching mode at -1.0 V(Ag/AgC1) is less than ca. 10/cm from low coverage to saturation coverage. Experiments using isotopic mixtures of 12CN and 13CN show that this shift is due to direct lateral interactions between adsorbed cyanide ions. Keywords: Infrared, Vibrational spectroscopy, Electrochemistry, Gold, Cyanide.

FOURIER TRANSFORM INFRARED SPECTROSCOPY

FOURIER TRANSFORM INFRARED SPECTROSCOPY

This report summarizes the effort to generate a library of quantitative infrared spectra of chemical warfare agents and related materials and biosimulants. The results of tests to validate the equipment and procedures to be used in the laboratory are discussed.

The traveling charge gun propulsion concept is being explored at the Ballistic Research Laboratory. A traveling charge is one in which the propellant is attached to the projectile, and for which burning rates in the range of 100- 500 m/s are required. The role of borohydride compounds in very high burning rate (VHBR) materials has been studied using two nitramines (cyclotrimethylene trinitramine, or RDX, and cyclotetramethylene tetranitramine, or HMX) and three boron compounds (the potassium and tetramethylammonium salts of the B12H12-2 anion and NaBH4). Pyrolysis products of these materials have been separated by capillary gas chromatography, GC, and characterized by Fourier transform infrared (FTIR) spectroscopy. Two-component and three-component nitramine/ borohydride combinations, as well as pressed propellant formulations previously tested in the closed bomb, have been studied in order to determine which reaction products of the nitramines are modified by the boron compounds. In addition to the permanent gas products typically observed, larger molecular weight species including amides and nitroso compounds have been identified. The product distributions suggest that the rate of energy release is greater in the nitramine/boron systems than that of either borohydride or nitramine alone, and that decomposition occurs at a lower temperature in the nitramine/borohydride mixtures than with the nitramine alone. These conclusions are also supported by DSC results. Keywords: RDX, HMX, Hivelites, TAGN, Thermal analysis, FTIR, Pyrolysis gc.

The measurement of infrared spectra of tactical aircraft has been a mainstay in providing signatures for both analysis and simulation to missile seeker designers for many years. Whereas many modern air vehicles have seen their intrinsic infrared signatures reduced over time, the variation in atmospheric backgrounds remains a natural phenomenon which has placed limitations on both operational characteristics of field measurement and the accuracy with which weak targets may be characterized. This paper presents a heuristic method for reducing errors introduced by natural variations in backgrounds in spectral background subtraction. The motivation behind the new technique is discussed as well as the theoretical development of the new technique to reduce spectral background induced errors. An example showing measurements of a small model aircraft are presented with both corrected and uncorrected results. These results are contrasted with apriori expectations of the aircraft signature to provide specific instances when uncorrected background induced errors can limit the measurement accuracy of weak or suppressed air vehicles.

Modern observations of infrared molecular lines in planets are performed at spectral resolutions which are as high as those available in the laboratory. Analysis of such data requires laboratory measurements at the highest possible resolution, which also yield accurate line positions and intensities. For planetary purposes the spectrometer must be coupled to sample cells which can be reduced in temperature and varied in pressure. An approach which produces the full range of required molecular line parameters uses a combination of tunable diode lasers and Fourier transform spectrometers (FTS). The FTS provides board spectral coverage and good calibration accuracy, while the diode laser can be used to study those regions which are not resolved by the FTS.

Subtractively normalized interfacial Fourier transform infrared spectroscopy (SNIFTIRS) was used to follow the potential dependent reorientations undergone by isoquinoline molecules that are adsorbed at a mercury electrode surface. The differences in the relative intensity changes on reorientation between the in-plane and out-of-plane vibrational modes have been explained in terms of field-induced infrared absorption.

To ensure the optimum performance of military aircraft engines the chemical and physical condition of their oil must be monitored with time in service. Normal testing methods require a significant cost and time overhead, so the ability of one test instrument to monitor the condition of the oil is an essential requirement of modern condition-based oil analysis. This paper describes the use of a Fourier Transform Infrared (FTIR) instrument coupled with a powerful chemometrics-based analysis technique to monitor oil acidity, viscosity, load carrying additives, water, and antioxidant concentrations in synthetic turbine oils from a series of in-service TF30 engines. The FTIR chemometrics-based technique was found to offer confidant prediction of these oil condition properties and to be a suitable technique for oil condition monitoring for the TF30 engine oil system. However, further refinement of the technique would be required before allowing it to be used by non-skilled operators. The authors conclude that oil condition monitoring of synthetic turbine oils can be performed successfully using FTIR coupled with chemometric modeling. It is possible to accurately determine oil viscosity, TAN, antioxidant concentration, and load carrying additive concentration. The model is not suitable for the prediction of water content, but this capability would be easily added with a small amount of extra oil analysis and simple recalibration of the predictive model. Specific test results are appended. (numerous tables, 5 refs.)

This report documents findings of work performed under U.S. Army Chemical Research, Development and Engineering Center (CRDEC) Contract No. DAAA15-86-0020, by contractor personnel in conjunction with CRDEC scientists. This research addressed the sampling of organophosphorus compounds from the air and their detection using Fourier transform infrared (FTIR) techniques with computer-aided pattern recognition. Vapor samples from a thermoelectrically- cooled plate, typically used as a liquid aerosol collector, were examined to determine the feasibility of recording infrared emission spectra directly from the plate. A comparison of this method was made with gas chromatography/infrared (GC/IR) spectroscopy analysis of samples that were first removed from the plate. Keywords: Infrared, FTIR, Malathion, Infrared emission, Infrared spectra, Pattern recognition, Infrared transmittance, Cold mirror/plate.

A balloon-borne liquid nitrogen cooled Fourier transform spectrometer system was test-flown from Holloman Air Force Base on 8 October 1980. The system and the modifications to it required for balloon application are described and the flight results discussed. Samples of the interferograms obtained during the flight and their transforms are presented. Procedures for improving the performance on subsequent flights are discussed. (Author)

A balloon-borne liquid nitrogen cooled Fourier transform spectrometer system was test-flown from Holloman Air Force Base on 8 October 1980. The system and the modifications to it required for balloon application are described and the flight results discussed. Samples of the interferograms obtained during the flight and their transforms are presented. Procedures for improving the performance on subsequent flights are discussed. (Author)

Software routines for generating synthetic Fourier transform infrared (FT-IR) spectra and interferograms are documented. Infrared radiative transfer models for passive FT-IR spectroscopy are furnished, providing a basis for simulating realistic spectral data. Laboratory passive FT-IR spectra and interferograms are shown to validate the software performance. Due to variability in reported absorption coefficients, it is found that simulated data are not a replacement for either laboratory or field quantitative measurements. However, the synthetic data capability provides a versatile resource for examining experimental results and a flexible tool for chemometric research into various signal processing strategies for passive FT-IR spectroscopy. The software routines in the "FTIR_Toolbox" are written in MATLAB. Complete program source code listings are provided in the appendix.

Capparis divaricata lam commonly known as caper bush, belonging to genus Capparidaceae, found throughout India. In this study, we determine the phytocomponents in dried leaf and fruit peel extract of Capparis divaricata lam (cappardaecea).The FTIR (Fourier transform infrared spectroscopy) spectroscopy is an essential tool for determining the composition and structure of organic compounds. The FTIR spectroscopy is an essential tool for profiling biochemical compounds that exist in herbal extraction, FTIR method was selected because it is a very rapid and economic method for the characterizing of a functional group. The dried sample has been taken for the identification of chemical bonds which are present in the plant sample. The FTIR peaks analyzed in leaf shows the OH, CH2, C=C, C-OH, CH3 and CH, bonds while in fruit peel it shows OH, CH2, C=C, C-OH, CH3, CH and C=O bonds. The presence of C=O bond tells us that they are useful in organic synthesis catalysis and as catalyst precursors in homogenous catalysis. The CH3 bonds suggest that the Methyl containing Amino Acid is present. The C-O-H group indicates the presence of Fatty Acids. Silicones and Sulfones the presence of various biological activities and are therapeutic targets. All the identified phytocomponents are having pharmacological activity and absorbance bond shows strong, stretching, symmetric and asymmetric bonds. So Capparis divaricata lam can be considered as a plant of phytopharmaceutical importance.

Background: The Siddha system of medicine is purely scientific and the peculiar complex system of science and philosophy. Fourier Transform Infrared Spectroscopy (FTIR) is certainly one of the most important analytical techniques for herbal medicine. FTIR can be implemented during herbal drug development in production for process monitoring or in quality control laboratories. Aim & Objective: The aim of study is to evaluate the morphology and elemental characterization of the Saaranai chooranam. The functional groups of their formulations are analysed through FTIR spectroscopy and the biological roles of the functional groups are discussed in this study. Materials and methods: The raw drugs is collected and purified as per Siddha literature. Drug Saaranai chooranam, which has been illustrated in the text Dr.S.Venkattarajan, Akasthiyar-2000, Part – III, Page: 102, for the management of Raththa Kothippu (Systemic Hypertension). Results: The Fourier Transform Infrared Spectroscopy compounds showed the presence of functional groups O-H Stretching (Alcohol), C-H Stretching (Alkane), O=C=O Stretching (Carbon dioxide), C-C bending (Alkene), O-H bending (Carboxylic acid), C-O Stretching (Aromatic ester), C-O Stretching (Tertiary alcohol), S=O Stretching (Sulfoxide), C-H bending (1,2-disubstituted) and C-1 Stretching (Halo compound) which ensures the therapeutic effect of the drug. Conclusion: The instrumental analysis FT-IRS study of Saaranai chooranam is the presence of functional groups through the stretch and bends which is responsible for its functional activity. The functional groups in Saaranai chooranam have diuretic and nervin tonic activities. This will ensure the efficacy and therapeutic effect of the drug.

FOURIER TRANSFORM INFRARED SPECTROSCOPY

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The approach for obtaining absorbance and transmittance spectra using a passive 3 to 5 micron Fourier transform infrared (FT-IR) spectrometer from two industrial stacks is documented. Independent knowledge of the stack plume temperature is key to generation of the single beam spectral ratio of differences that allows removal of instrumental effects from the absorbance and transmittance spectra. The empirical results are illustrated for two types of industrial stack in the form of summary graphs and tables. Appendixes in this report supply representative spectral data that is acquired with the 3 to 5 micron passive FT-IR spectrometer. Target plume constituents of sulfur dioxide, carbon dioxide, and nitrous oxide are discussed.

A balloon-borne liquid nitrogen cooled Fourier transform spectrometer system was test-flown from Holloman Air Force Base on 8 October 1980. The system and the modifications to it required for balloon application are described and the flight results discussed. Samples of the interferograms obtained during the flight and their transforms are presented. Procedures for improving the performance on subsequent flights are discussed. (Author)

A balloon-borne liquid nitrogen cooled Fourier transform spectrometer system was test-flown from Holloman Air Force Base on 8 October 1980. The system and the modifications to it required for balloon application are described and the flight results discussed. Samples of the interferograms obtained during the flight and their transforms are presented. Procedures for improving the performance on subsequent flights are discussed. (Author)

The hydrogen bonding behavior of segmented polyurethane elastomers and model hard segment compounds has been examined by performing simultaneous Differential Scanning Calorimeter (DSC) and Fourier Transform Infrared Spectroscopy (FTIR) measurements. In model hard segments of 4,4'-diphenylmethane diisocyanate (MDI) extended with (2,2,3,3-d4) butanediol (BDO), and 2,4-toluenediisocyanate also chain extended with BDO, the spectra show a linear decrease in the apparent degree of hydrogen bonding over most of the temperature range. In the case of MDI-BDO, there is thus no clear correlation between DSC multiple endotherms and the degree of hydrogen bonding. Examination of an elastomer containing 70% bwt. of MDI/BDO hard segment and polyether soft segment however reveals a transition in the degree of hydrogen bonding coincident with an endotherm whose origin has been previously ascribed to the onset of a microphase mixing transition. This result clearly demonstrates that thermally induced morphological changes can affect markedly the hydrogen bonding behavior of polyurethanes. The study also illustrates that chemical changes occur during a typical DSC thermogram. In particular, reversal of the polyurethane reaction equilibrium is evidenced by emergence of an isocyanate absorbance band at high temperatures for all materials.

As part of the Surface Cleanliness Verification project, sponsored by the Strategic Environmental Research and Development Program, the Naval Facilities Engineering Service Center conducted an investigation of grazing-angle reflectance Fourier Transform Infrared (FTIR) Spectroscopy as a tool for online cleanliness verification at DOD maintenance and repair facilities. In the project's first year, the feasibility of grazing-angle reflectance FTIR was demonstrated in the laboratory for the detection of organic contaminant residues on reflective surfaces. In Years 2 and 3 this technology was transitioned from the laboratory into a portable field device capable of detecting organic and certain inorganic contaminants on reflective surfaces at very sensitive levels ( 1.0 microgram/sq cm). Examples of DoD applications where surface cleanliness is critical include coating, plating and bonding of aircraft parts; beaming refurbishment; and shipboard surface tile mounting. Visual inspection and water break testing are often inadequate to detect contamination that may cause subsequent bonding or fouling problems if not removed.

This article is from Frontiers in Plant Science , volume 5 . Abstract Roots of forest trees are associated with various ectomycorrhizal (ECM) fungal species that are involved in nutrient exchange between host plant and the soil compartment. The identification of ECM fungi in small environmental samples is difficult. The present study tested the feasibility of attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy followed by hierarchical cluster analysis (HCA) to discriminate in situ collected ECM fungal species. Root tips colonized by distinct ECM fungal species, i.e., Amanita rubescens, Cenococcum geophilum, Lactarius subdulcis, Russula ochroleuca, and Xerocomus pruinatus were collected in mono-specific beech (Fagus sylvatica) and mixed deciduous forests in different geographic areas to investigate the environmental variability of the ECM FTIR signatures. A clear HCA discrimination was obtained for ECM fungal species independent of individual provenance. Environmental variability neither limited the discrimination between fungal species nor provided sufficient resolution to discern species sub-clusters for different sites. However, the de-convoluted FTIR spectra contained site-related spectral information for fungi with wide nutrient ranges, but not for Lactarius subdulcis, a fungus residing only in the litter layer. Specific markers for distinct ECM were identified in spectral regions associated with carbohydrates (i.e., mannans), lipids, and secondary protein structures. The present results support that FTIR spectroscopy coupled with multivariate analysis is a reliable and fast method to identify ECM fungal species in minute environmental samples. Moreover, our data suggest that the FTIR spectral signatures contain information on physiological and functional traits of ECM fungi.

This article is from PLoS ONE , volume 9 . Abstract Gypsum soils are among the most restrictive and widespread substrates for plant life. Plants living on gypsum are classified as gypsophiles (exclusive to gypsum) and gypsovags (non-exclusive to gypsum). The former have been separated into wide and narrow gypsophiles, each with a putative different ecological strategy. Mechanisms displayed by gypsum plants to compete and survive on gypsum are still not fully understood. The aim of this study was to compare the main chemical groups in the leaves of plants with different specificity to gypsum soils and to explore the ability of Fourier transform infrared (FTIR) spectra analyzed with neural network (NN) modelling to discriminate groups of gypsum plants. Leaf samples of 14 species with different specificity to gypsum soils were analysed with FTIR spectroscopy coupled to neural network (NN) modelling. Spectral data were further related to the N, C, S, P, K, Na, Ca, Mg and ash concentrations of samples. The FTIR spectra of the three groups analyzed showed distinct features that enabled their discrimination through NN models. Wide gypsophiles stood out for the strong presence of inorganic compounds in their leaves, particularly gypsum and, in some species, also calcium oxalate crystals. The spectra of gypsovags had less inorganic chemical species, while those of narrow gypsum endemisms had low inorganics but shared with wide gypsophiles the presence of oxalate. Gypsum and calcium oxalate crystals seem to be widespread amongst gypsum specialist plants, possibly as a way to tolerate excess Ca and sulphate. However, other mechanisms such as the accumulation of sulphates in organic molecules are also compatible with plant specialization to gypsum. While gypsovags seem to be stress tolerant plants that tightly regulate the uptake of S and Ca, the ability of narrow gypsum endemisms to accumulate excess Ca as oxalate may indicate their incipient specialization to gypsum.

This article is from Journal of Pharmacy & Bioallied Sciences , volume 5 . Abstract AIM:: The current work is aimed at understanding the effect of pH on the thermal stability of hen egg white lysozyme (HEWL) at high concentration (200 mg/mL). MATERIALS AND METHODS:: Fourier Transform Infrared (FTIR) Spectroscopy with modified hardware and software to overcome some of the traditional challenges like water subtraction, sample evaporation, proper purging etc., are used in this study. RESULTS:: HEWL was subjected to thermal stress at pH 3.0-7.0 between 25°C and 95°C and monitored by FTIR spectroscopy. Calculated Tm values showed that the enzyme exhibited maximum thermal stability at pH 5.0. Second derivative plots constructed in the amide I region suggested that at pH 5.0 the enzyme possessed higher amount of α-helix and lower amount of aggregates, when compared to other pHs. CONCLUSIONS:: Considering the fact that HEWL has attractive applications in various industries and being processed under different experimental conditions including high temperatures, our work is able to reveal the reason behind the pH dependent thermal stability of HEWL at high concentration, when subjected to heat denaturation. In future, studies should aim at using various excipients that may help to increase the stability and activity of the enzyme at this high concentration.

Light off temperatures of oxidation catalysts are considered as one of the important parameters for catalyst performance evaluation. In this study, the in situ Fourier Transform IR technique was developed and used to determine the light-off temperatures and reaction products of three three-way automotive catalysts with 20 torr monomethylamine in air at 0.5 L/min flow rate. Light-off temperatures were 140, 143, and 170 C for Davison, Allied-Signal, and Degussa oxidation catalysts, respectively. CO, CO2, H2O, and nitric acid were the major oxidation products. The activation energies of formation of CO and CO2 on the catalysts were also determined. Keywords: Light off temperature, Fourier transform; Infrared spectroscopy; Oxidation products; Oxidation; Catalyst.

Light off temperatures of oxidation catalysts are considered as one of the important parameters for catalyst performance evaluation. In this study, the in situ Fourier Transform IR technique was developed and used to determine the light-off temperatures and reaction products of three three-way automotive catalysts with 20 torr monomethylamine in air at 0.5 L/min flow rate. Light-off temperatures were 140, 143, and 170 C for Davison, Allied-Signal, and Degussa oxidation catalysts, respectively. CO, CO2, H2O, and nitric acid were the major oxidation products. The activation energies of formation of CO and CO2 on the catalysts were also determined. Keywords: Light off temperature, Fourier transform; Infrared spectroscopy; Oxidation products; Oxidation; Catalyst.

This volume was digitized and made accessible online due to deterioration of the original print copy.

The Joint Oil Analysis Program Technical Support Center (JOAP-TSC) was tasked by the U.S. Air Force to determine the appropriateness of various oil analysis techniques to provide early warning of abnormal operating conditions. The study analyzed tilde 1300 samples from F-16, F110-GE100 gas turbine engines by spectroscopy (AES and FT-IR) and direct reading and analytical ferrography. A statistical analysis of the data collected is presented.

It is imperative that sensor technology in the mid infrared spectral range advance beyond the performance boundaries of the current generation of devices. Most high sensitivity mid-IR band detectors at high modulation frequencies are based on the cooled Mercury Cadmium Telluride (MCT) device operating in photoconductive or photovoltaic mode. While much engineering effort has been expended in the development of this and related detector technologies, for battlefield use the system suffers from the requirement of a cryogenic cooling mechanism. This adds weight and maintenance complexity. There are several pyroelectric devices available (e.g. deuterated triglycine sulfate, DTGS) which have better responsivity than an MCT detector at room temperature and at low modulation frequencies, but none which compares favorably with its performance when the detector is operating at 77 K and at high modulation frequencies. A conceptual alternative to this detection scheme is to use a photoacoustic detector. While the photoacoustic detector is an energy integrating device and thus suffers from 1/f responsivity loss, it can be made to function at room temperature with very inexpensive, light-weight components.

FOURIER TRANSFORM INFRARED SPECTROSCOPY

One possible origin of prebiotic organic material is that these compounds were formed via Fischer-Tropsch-type (FTT) reactions of carbon monoxide and hydrogen on silicate and oxide grains in the warm, inner-solar nebula. To investigate this possibility, an experimental system has been built in which the catalytic efficiency of different grain-analog materials can be tested. During such runs, the gas phase above these grain analogs is sampled using Fourier transform infrared (FT-IR) spectroscopy. To provide quantitative estimates of the concentration of these gases, a technique in which high-resolution spectra of the gases are calculated using the high-resolution transmission molecular absorption (HITRAN) database is used. Next, these spectra are processed via a method that mimics the processes giving rise to the instrumental line shape of the FT-IR spectrometer, including apodization, self-apodization, and broadening due to the finite resolution. The result is a very close match between the measured and computed spectra. This technique was tested using four major gases found in the FTT reactions: carbon monoxide, methane, carbon dioxide, and water. For the ranges typical of the FTT reactions, the carbon monoxide results were found to be accurate to within 5% and the remaining gases accurate to within 10%. These spectra can then be used to generate synthetic calibration data, allowing the rapid computation of the gas concentrations in the FTT experiments.

Infrared studies of the solid-melt phases of a homologous series of organobis (ammonium nitrate) salts (1,2- ethanediammonium dinitrate through 1,6- hexanediammonium dinitrate) are described. Fast thermolysis experiment involving selected organoammonium and orgaodiammonium nitrate salts are also described. Conclusions related to the solid phase and thermolysis studies are presented.

Many different polymeric insulations, such as silicones, epoxies, polyethylenes, etc., are in use. Unfortunately, these materials exhibit decreasing resistance to electrical stress with time. In order to characterize these degradation processes and to suggest materials changes that will ameliorate them, we are developing Fourier transform infrared spectroscopy (FTIR) techniques to look for molecular changes that occur before breakdown and which may therefore be used as a 'distant early-warning line' for impending breakdown.

This article is from BMC Biophysics , volume 4 . Abstract Background: Fourier transform infrared spectroscopy (FTIR) has been used as analytical tool in chemistry for many years. In addition, FTIR can also be applied as a rapid and non-invasive method to detect and identify microorganisms. The specific and fingerprint-like spectra allow - under optimal conditions - discrimination down to the species level. The aim of this study was to develop a fast and reproducible non-molecular method to differentiate pure samples of Bacillus spores originating from different species as well as to identify spores in a simple matrix, such as the clay mineral, bentonite. Results: We investigated spores from pure cultures of seven different Bacillus species by FTIR in reflection or transmission mode followed by chemometrical data treatment. All species investigated (B. atrophaeus, B. brevis, B. circulans, B. lentus, B. megaterium, B. subtilis, B. thuringiensis) are typical aerobic soil-borne spore formers. Additionally, a solid matrix (bentonite) and mixtures of benonite with spores of B. megaterium at various wt/wt ratios were included in the study. Both hierarchical cluster analysis and principal component analysis of the spectra along with multidimensional scaling allowed the discrimination of different species and spore-matrix-mixtures. Conclusions: Our results show that FTIR spectroscopy is a fast method for species-level discrimination of Bacillus spores. Spores were still detectable in the presence of the clay mineral bentonite. Even a tenfold excess of bentonite (corresponding to 2.1 × 1010 colony forming units per gram of mineral matrix) still resulted in an unambiguous identification of B. megaterium spores.

In situ surface infrared (IR) spectroelectrochemistry is used to investigate the adsorption of sulfate (SO4(2-)) and bisulfate (HSO(4-)) ions on polycrystalline gold surfaces in sodium sulfate and sulfuric acid, and also during copper underpotential deposition in sulfuric acid medium. In sodium sulfate solution, IR peaks due to surface sulfate and bisulfate are observed at potentials within the double-layer region on gold, and the ratio of IR peak intensities for sulfate to bisulfate increases as the applied potential is made more negative. In sulfuric acid, surface IR spectra indicate that adsorbed sulfate is favored at more positive potentials, while adsorbed bisulfate is prevalent at more negative voltages; also, a potential-dependent reorientation of water is observed in the spectra. IR spectroelectrochemical data from a sulfuric acid system containing copper sulfate indicate that adsorbed sulfate is present on gold at more positive potentials, and its coverage increases when underpotentially deposited (UPD) copper is present on the gold substrate surface.

The subtractively normalized interfacial Fourier transform infrared spectra (SNIFTIRS) of the difluorobenzenes in perchloric acid solutions show that the species are absorbed flat at low concentrations of the substrate. In concentrated solutions, the packing changes to a skewed configuration. For these molecules there is no indication of vibrational coupling to the strong electrical field at the electrode surface and the vibrational spectra are as predicted by the standard surface selection rule.

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Fourier transform infrared spectroscopy (FT-IR) using a photoacoustic sampling cell has been used to obtain high quality infrared spectra of various fiber-reinforced epoxy composites and the corresponding resin matrixes. Photoacoustic spectroscopy (PAS) offers the advantages of having little or no sample preparation for high quality spectra to be obtained and no alignment of the infrared incident beam is necessary. This makes PAS an ideal sampling method for in-field testing of composite laminates. The spectra revealed information on the degree of cure of the resin system by monitoring the 915/cm absorption band and the type of reinforcement material used (glass or Kevlar).

Fourier transform infrared spectroscopy (FT-IR) using a photoacoustic sampling cell has been used to obtain high quality infrared spectra of various fiber-reinforced epoxy composites and the corresponding resin matrixes. Photoacoustic spectroscopy (PAS) offers the advantages of having little or no sample preparation for high quality spectra to be obtained and no alignment of the infrared incident beam is necessary. This makes PAS an ideal sampling method for in-field testing of composite laminates. The spectra revealed information on the degree of cure of the resin system by monitoring the 915/cm absorption band and the type of reinforcement material used (glass or Kevlar).