Fourier Transform Infrared Absorption Research Articles

Weighted LASSO variable selection for the analysis of FTIR spectra applied to the prediction of engine oil degradation

The aim of this work is to quantify the relationship between different methods of artificial oil alteration as well as engine oils collected from a passenger car using FTIR (Fourier-transform infrared) spectroscopic data and chemometric methods. We propose a comprehensive procedure for the analysis of FTIR spectra: First, a reconstruction error based pre-processing to filter non-informative variables is introduced, then simultaneous variable selection and parameter estimation using the (weighted) LASSO is performed. Eventually, post-selection inference is applied to derive confidence intervals for the selected model coefficients. The proposed pre-processing methods do not rely on manual selection of FTIR absorption bands suitable for analysis but perform filtering of non-informative variables objectively. With weighted LASSO, experts’ knowledge can be integrated with the model. This pipeline for the analysis of FTIR spectroscopic data is demonstrated and validated on a real-world dataset including series of FTIR spectra of used and artificially altered engine oils.

Measuring H2O concentrations in olivine by secondary ion mass spectrometry: Challenges and paths forward

Abstract Trace concentrations of H2O in olivine strongly affect diverse mantle and magmatic processes. H2O in olivine has been difficult to accurately quantify due to challenges in sample preparation and measurement, as well as significant uncertainties in standard calibrations. Here we directly compare secondary-ion mass spectrometry (SIMS) measurements of the olivine standards of Bell et al. (2003, hereafter Bell03) and Withers et al. (2012, hereafter Withers12) upon which most SIMS and Fourier transform infrared (FTIR) spectroscopy analyses are based. In the same SIMS session, we find that the olivine standards from the two studies are offset by ~50%, forming lines of different slope when comparing SIMS measurements to the independent nuclear reaction analysis (NRA) in Bell03 and elastic recoil detection analysis (ERDA) in Withers12. This offset is similar to the ~40% offset that exists in the FTIR absorption coefficients determined by those two studies, and points to the NRAERDA data as the cause for the offset more than different IR absorption characteristics of the different olivines. We find that the Withers12 olivine standards form the most precise calibration line, and that the measured Bell03 olivine standards have issues of reproducibility and accuracy due to the presence of hydrous inclusions (as documented previously by Mosenfelder et al. 2011). Owing to the limited availability of the Withers12 olivine standards, however, we recommend using orthopyroxene standards (Kumamoto et al. 2017) to calibrate H2O in olivine by SIMS due to similar calibration slopes. We revise the reference values of current orthopyroxene standards to account for uncertainties in the Bell et al. (1995) manometry data. With these revised values, the orthopyroxene calibration line is within 12% of the Withers12 olivine line, which is within the long-term uncertainty of the SIMS olivine measurements. We apply our SIMS calibration protocol to revise estimates of the partition coefficients for H2O between olivine and melt, resulting in a value of 0.0009 ± 0.0003 at pressures ~0.2–2 GPa. This brings into closer agreement between the partition coefficients determined from experimental studies and those based on natural studies of olivine-hosted melt inclusions.

Exploration of the Crystal Structure and Thermal and Spectroscopic Properties of Monoclinic Praseodymium Sulfate Pr2(SO4)3.

Praseodymium sulfate was obtained by the precipitation method and the crystal structure was determined by Rietveld analysis. Pr2(SO4)3 is crystallized in the monoclinic structure, space group C2/c, with cell parameters a = 21.6052 (4), b = 6.7237 (1) and c = 6.9777 (1) Å, β = 107.9148 (7)°, Z = 4, V = 964.48 (3) Å3 (T = 150 °C). The thermal expansion of Pr2(SO4)3 is strongly anisotropic. As was obtained by XRD measurements, all cell parameters are increased on heating. However, due to a strong increase of the monoclinic angle β, there is a direction of negative thermal expansion. In the argon atmosphere, Pr2(SO4)3 is stable in the temperature range of T = 30–870 °C. The kinetics of the thermal decomposition process of praseodymium sulfate octahydrate Pr2(SO4)3·8H2O was studied as well. The vibrational properties of Pr2(SO4)3 were examined by Raman and Fourier-transform infrared absorption spectroscopy methods. The band gap structure of Pr2(SO4)3 was evaluated by ab initio calculations, and it was found that the valence band top is dominated by the p electrons of oxygen ions, while the conduction band bottom is formed by the d electrons of Pr3+ ions. The exact position of ZPL is determined via PL and PLE spectra at 77 K to be at 481 nm, and that enabled a correct assignment of luminescent bands. The maximum luminescent band in Pr2(SO4)3 belongs to the 3P0 → 3F2 transition at 640 nm.

Homogeneous nucleation in polyamide 66, a two-stage process as revealed by combined nanocalorimetry and IR spectroscopy

Nanocalorimetry and Fourier transform infrared (FTIR) spectroscopy are combined to measure the calorimetric properties and molecular spectra of the same sample (sample amount about 5 ng) of polyamide 66 (PA66). By determining IR difference absorption spectra between a quenched and a sample annealed at varying temperatures (Ta) and annealing time (ta), the initial steps of homogeneous nucleation is for the first time revealed on a molecular scale, long before crystallization takes place. As starting point (i), isolated H-bonds are formed between (N–H) and (C = O) moieties of adjacent (neighboring) polymer segments promoted by far-reaching dipole–dipole interactions. In the second step (ii), the H-bonds realign, which in part requires the opening of already established H-bonds. In stage (i), the FTIR absorption intensity of the free (C = O)f moieties decreases while that of the H-bonded (C = O)b ones increases as a function of Ta at constant ta. This implies an increase in the H-bonding network in amorphous domains. The second stage of nucleation in the studied PA66 is characterized by an increase in the number of (C = O)f and a corresponding decrease in (C = O)b moieties as the sample transitions to the ordered crystalline structure. This is attributed to a change from γ to α polymorphs in PA66. The non-polar methylene units in PA66 are largely unaffected during the nucleation steps, where no changes in the overall heat capacity are detectable, proving that these changes occur prior to the onset of crystal growth.Graphical abstract

Durable polyolefin encapsulants in aged photovoltaic modules

We investigated the long-term durability of thermoplastic polyolefin (TPO) encapsulants in crystalline-silicon (c-Si) photovoltaic (PV) modules that were exposed for up to approximately 10 years or damp-heat (DH)-exposed at 85 °C and 85% relative humidity (RH). No significant degradation was observed in c-Si PV module based on the TPO encapsulant after a long-term DH test at 85 °C/85% RH for 8000 h. The Fourier transform-infrared absorption spectrum indicated that oxidative degradation of the TPO encapsulant in the module occurred on the glass side after the DH test, whereas the oxidative products of the TPO encapsulant did not decrease the PV performance of the module. No significant oxidative degradation of the TPO encapsulant in the module was observed after approximately 9 years of outdoor exposure by Raman spectroscopic measurements. Our results indicate that TPO is a promising alternative encapsulation material for enhancing the long-term durability of c-Si PV modules furthermore.

Structural studies on varied concentrations of europium doped strontium phosphate glasses

In this study, the conventional melt quenching method was used to prepare pure and the europium-doped strontium phosphate-based glasses. This study aims to discover the effect of the europium content on the structural properties of synthesized glasses. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) absorption spectra were employed to examine the structural characterization of these prepared samples. XRD analysis shows that all samples of undoped and europium-doped phosphate glasses have amorphous phases. The FTIR absorption spectra demonstrated that various structural phosphate groups have been represented in the synthesized samples. The europium-doped strontium phosphate glasses can be used in many applications such as laser, optoelectronics, LED display, solar cells, and photonic devices. [Copyright information to be updated in production process].

Removal of Fe (II) ions from Aqueous solution using Rice-husk Adsorbents in fixed-bed column

Rice husk has been converted into activated carbon for the adsorbent to remove the heavy metal from the aqueous solution. This study aimed to convert rice husk to activated carbon (AC) for use in the adsorption of Fe ions in a fixed-bed column. Rice husk was first pyrolyzed in an atmosphere of nitrogen gas at 400 oC, then a chemical activation method using sodium hydroxide. The rice husk activated carbon (RH-AC) was characterized using Fourier transform infrared (FTIR) and Scanning electron microscope (SEM) to identify the functional group and microstructure of carbon. The performance of the carbon was tested on the Fe removal from an aqueous solution in a continuous column. The adsorption process was carried out using Fe solution with an initial concentration of 3 mg/L as an artificial sample. The amount of carbon is 25, and 50 g were filled in an adsorber column with a diameter of 5.4 cm and height of 40 cm. SEM images revealed that the activated carbons shown with well-developed pore sizes and pore structure were produced after the chemical activation. The FTIR absorption bands observed in the RH-AC sample confirmed the presence of hydroxyl (-OH), carbonyl, and carboxylic (-COOH) groups of RH-AC adsorbent. The highest Fe removal efficiencies were 91.9% on chemically activated carbon and column mass 50 g at 400 minutes. The overall study revealed the potential value of chemically activated RH-AC as a possible commercial adsorbent in a continuous column wastewater treatment strategy.

Removal of Cd (II) Ions from Bioretention System by Clay and Soil Wettability

In this work, a silane modifier with benzyl substitutes (OFS-B) and linear substitutes (OFS-L) was used to modify bentonite clay and soil, and the results were characterized by Fourier transform-infrared absorption spectroscopy (FT-IR) and powder-X-ray diffraction (XRD) analysis. A contact angle analysis was performed to determine the wettability of modified clay and soil. The findings revealed that silane-modified OFS-L clay and soil produced wettable surfaces, while OFS-B exhibited hydrophobic properties. These clays and soils were used in a bioretention system for Cd (II) removal. In the study, seven different types of bioretention systems, including natural, OFS-L, and OFS-B modified clay and soil, as well as natural, OFS-L, and OFS-B modified soil, were applied to Cyperus alternifolius plants without an additional layer. The removal capacity of Cd (II) was measured in the following order: modified clay > modified soil > original clay/soil > no layer, i.e., 99.48%, 92.22%, 88.10/78.5%, and 30.0%, respectively. OFS-L removed more Cd (II) than OFS-B during the modification. OFS-L now improves the bioavailability and accumulation of Cd (II) in the plant (18.5 µg/g) and has a higher chlorophyll-b concentration (1.92 mg/g fresh weight) than other systems. The wettable clay exhibited clay leaching into the various levels of the bioretention system. In the bioretention system, benzyl substituted clay prevented the penetration of water and formed a Cd (II) agglomeration. When compared to non-wettable modifiers, these results indicated that wettable clay material could be a capable material for removing Cd (II).

Preparation and characterization of the plasticized polylactic acid films produced by the solvent‐casting method for food packaging applications

A strategy to overcome the brittleness and rigidity of polylactic acid (PLA)-based materials for food packaging applications is adding a proper plasticizer in the right amount. Here, triacetin (TA) and polyethylene glycol (PEG) were used as plasticizers in different amounts (10, 20, and 30 wt%) to produce the plasticized PLA films by the solvent-casting method. Tensile properties, water vapor permeability (WVP), moisture content (MC), optical properties, Fourier transform infrared absorption (FTIR), and thermogravimetric analysis (TGA) are reported. The results showed that both TA and PEG cause increasing elongation at break (Eab) and decreasing tensile strength (TS), where the plasticized PLA films containing 10 and 30 wt% of TA showed the highest TS (26.6 MPa) and Eab (81.1%), respectively. Light transmission of PLA was decreased by introducing the plasticizers, while WVP, MC, and opacity of the plasticized films were increased compared to the neat PLA. Among the plasticized films, the sample with 10 wt% of TA and PEG showed the lowest WVP (4.9 × 10−10 g/m s−1 Pa−1) and MC (5.5%), respectively. Based on the TGA, an improvement in the thermal stability of TA and PEG plasticized films compared to the neat PLA was obvious. The sample containing 10 wt% of TA (PLA-TA10) showed the best performance for food packaging applications. Practical applications Food product packaging provides retarding deterioration, reducing microbial contamination, preserving safety, protecting quality, and extending the shelf life of packaged foods during transmission, storage, and consumption. Petroleum-based plastic and synthetic polymers have been mainly used in food packaging due to their cheap cost and good mechanical and barrier properties. However, increasing the use of these nonbiodegradable polymers causes serious environmental and health problems. The biopolymers which are extracted from biodegradable and renewable sources are considered as suitable alternatives for petroleum-based plastic materials. However, application of biopolymers as packaging materials has been limited due to their low mechanical properties and thermal stability. Many studies have been conducted to modify the properties of PLA-based packaging materials to create a favorable product for the food industry. Moreover, introducing plasticizer to PLA helps to develop biocomposite materials with unique characteristics for food packaging. This article shows an improvement in the properties of the PLA-based composites for food packaging applications.

Optical properties of GeO[SiO] and GeO[SiO2] solid alloy layers grown at low temperature

The optical properties of GeO[SiO] and GeO[SiO2] solid alloy films grown on Si(001) substrates were studied using Raman, Fourier transform infrared absorption (FTIR) and photoluminescence (PL) spectroscopies. A PL signal was observed in the infrared region both for as-deposited and annealed germanium silicate suboxide films. Furnace annealing led to an increase of the PL signal and to a redshift of the PL maximum. The PL at ∼1100 nm is most probably due to defect-induced radiative transitions while the PL at ∼1500 nm may be rather caused by amorphous Ge nanoclusters and Ge nanocrystals. Finally, the temperature dependence of the PL was studied. Anomalous quenching of the PL signal is observed which does not follow the classical Arrhenius law. The temperature dependence of the PL intensity is well explained by using a Berthelot model.

Functional codoped ZnSe:Cu, Mn quantum dots(QDs): Microstructure, calorimetric and photoluminescence properties

In the present work, undoped ZnSe, and Zn1-x-y Cux Mny Se (x = 0.001, y = 0, 0.001, 0.010 0.015, 0.02 and 0.04 mol) codoped-quantum dots (cdQDs) of mean crystallite size within the range of 1.12 to 1.63 nm are synthesized employing the simple microwave irradiation (MWIR) assisted method; Different synthesis regimes of variable MWIR times and also Mn content are performed for ZnSe:Cu-Mn QDs. Structural, optical properties and melting point of the as-synthesized ZnSe QDs are studied by XRD, FESEM equipped with EDX and Map, TEM, Fourier transform infrared (FTIR) and differential scanning calorimetry (DSC) analysis. XRD confirms the incorporation of Mn and Cu in ZnSe structure with the tunable size by changing the synthesize conditions; TEM results indicate spherical particles, most of which had a diameter of about 5 nm. Results of photoluminescence (PL) investigations show the synthesis condition dependence nature of the samples, suggesting their application in green-region sensors/biosensors; Mn doping causes more extent of PL in to the light wavelengths; doping with transition metals (TMs) impurities and employing MWIR cause an enhancement in the intensity and peak shift of PL band toward higher wavelengths, which influence on the optical properties of semiconductors. The FTIR absorption peaks for the understudied samples show the formation of ZnSe structure (the interaction between Se2− and Zn2+ ions) and insertion of Mn and Cu ions into their lattices; The Experimental and empirical melting temperature of synthesized nanomaterial are investigated; DSC analysis shows that nanoparticles melting point of the present nanoparticles are 600 °C lower than that of the bulk ZnSe owing melting point of 1520–1525 °C. Empirical size dependency of melting point shows that at lower than the Bohr radius of ZnSe (~8 nm), reasonable fast decrease in melting point occurs.

Iron oxide nanoparticles synthesized using garlic and onion peel extracts rapidly degrade methylene blue dye

Iron oxide nanoparticles (IONPs) were synthesized by combining garlic and onion peel extracts with iron (III) chloride salt (FeCl3) in a simple chemical method to develop an environmentally green treatment for toxic dyes. Onion and garlic peels act as reducing, stabilizing, and anti-caking agents to rapidly transform FeCl3 salt into IONPs. A change in the color of the resulting solutions indicates the formation of IONPs. X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), UV–visible (UV–vis), and Fourier-transform infrared (FTIR) spectroscopy were used to characterize the structural and optical properties of IONPs. The FeO NPs were constructed using a garlic peel extract. They were 34–70 nm in size with a cubic structure, while the Fe2O3 NPs synthesized using an onion peel extract were 37–66 nm in size with a hexagonal structure. FE-SEM images showed the biosynthesized FeO NPs had a nanosheet-like structure with a particle size of 24–44 nm, and biosynthesized Fe2O3 NPs demonstrated a nanofiber-like structure with a particle size of 29–32 nm. UV–vis measurements indicated a blue shift for the energy gap value from 3.1 eV for biosynthesized FeO NPs to 4.1 eV for biosynthesized Fe2O3NPs. The strong FT-IR absorption peaks at 650 and 660 cm−1represented an Fe–O vibration band for the biosynthesized FeO and Fe2O3 NPs, respectively. Methylene blue (MB) degradation was rapid using biosynthesized Fe2O3 and FeO NPs, reaching 97% at 30 min and 90% at 35 min. These degradation rates indicate the effectiveness of the application of IONPs in the removal of MB dye through the adsorbent process. Green synthesis of iron oxide nanoparticles (IONPs) were prepared by combining (garlic and onion) peels extract with iron chloride (III) salt (feCl3) through a simple chemical method at 200 °C for 2 h. The main objective of this research is the environment treatment of toxic dyes. The (onion and garlic) peels acts as a reducing, stabilizing, and anti-caking agent to transform FeCl3 salt to IONPs in a short period of time. It is observed that a change in the color of the resulting solutions indicates the formation of IONPs. By using different physical techniques such as X-ray Diffraction (XRD), Field Emission-Scanning Electron Microscopy (FE-SEM), UV–Visible (UV–Vis), Fourier Transform Infrared (FT-IR), the structural and optical properties of IONPs were characterized. The crystallite size of FeO NPs using the garlic peel extract ranged from (34–70) nm with a cubic structure, while the crystallite size increased from (37–66) nm for Fe2O3 NPs synthesized using the onion peel extract with a hexagonal structure. FE-SEM images showed a nanosheet-like structure with a particle size of (24–44) nm for FeO NPs synthesized using the garlic peel extract. The morphology of Fe2O3 NPs synthesized using the onion peel extract revealed a nanofiber-like structure with a smaller particle size of (29–32) nm. UV–vis measurements indicated a blue shift for the energy gap value from 3.1 eV for FeO NPs using the garlic peel extract to 4.1 eV for Fe2O3 NPs using the onion peel extract. The peak of strong absorption at 650 and 660 cm−1 indicated that an Fe–O vibration band reported on the FT-IR spectrum belongs to FeO and Fe2O3 NPs using the garlic and onion peel extract, respectively. This experiment indicates successful removal of methylene blue (MB) by application of IONPs through the adsorbent process. The results of quick degradation efficiency of MB dye by Fe2O3 NPs prepared using the onion peel extract reached 97% at 30 min, with high photocatalytic activity than that observed with FeO NPs prepared using the garlic peelextract, for which the degradation efficiency was 90% at 35 min.

Mid-infrared spectroscopy of hemispherical water droplets

As an important component of atmospheric aerosols, water is profoundly related with aerosol hygroscopicity and provides a medium for atmospheric heterogeneous reactions. The quantitative analysis of water content in aerosol droplets is instrumental to understanding atmospheric chemistry, as well as to addressing the related environmental issues, such as air pollution and climate change. Fourier transform infrared (FTIR) spectroscopy has been widely adopted to quantify the amount of water content in atmospheric aerosols, which is based on the absorbance of OH functional group in proportion to water content. However, in the OH stretching vibration band around 3400 cm−1, spectral distortions may occur, making a quantitative analysis impossible. In addressing this issue, here we put forth a model to simulate the FTIR absorption of hemispherical water droplets, along with a quantitative description of the spectral distortion. Our model prediction was benchmarked with the microscopic-FTIR experiments conducted on sodium sulfate droplets, and good agreements between theoretical and experimental results were found. We observed that the absorbance spanning across the mid-wavenumber infrared region increases with water absorption coefficients; while such an increasing trend was not seen in the 3400 cm−1 band. We speculate that the spectral saturated absorption is related to the absorption coefficient of water and the ratio of the projected area of droplets to the aperture area. In addition, the effects of droplet size and number density on the absorption spectra were investigated. The waveband range of the saturated absorption broadens with an increase in droplet radius. On the other hand, as the number density of water droplets increases, the absorption at 3400 cm−1 is enhanced, and the characteristic peak of condensed water becomes increasingly sharper, asymptotic to the typical infrared spectra of water collected by the pressing method.

Water content quantification by FTIR in carboxymethyl cellulose food additive

ABSTRACT Water content quantification of raw polysaccharide materials for food processing is generally performed by gravimetric analysis or titrimetric methods, which are time- and energy-consuming, non-eco-friendly and sample destructive. The present study develops and validates a new approach, based on the use of Fourier transform infrared (FTIR) spectroscopy, resulting in a model of the water content of carboxymethyl cellulose (CMC) polysaccharides. Samples of CMC were exposed to different relative humidity conditions. Water content was determined by standard gravimetric methods (OIV-Oeno 404–2010) and compared with the area of FTIR absorption in the range 3675–2980 cm−1, attributed to the stretching of OH groups. The strong correlation between gravimetric results and FTIR area (R2 = 0.88) showed no signs of bias across the water content range. A cross-validation technique to predict the water content by band area was assessed obtaining a general equation: y = 2.12 x + 2.80 with a high repetitively and good prediction of the tested models.

Plumbing the depths of the graphene wetting controversy

Plumbing the depths of the graphene wetting controversy

Formation of extraordinary density alkanethiol self-assembled monolayers on surfaces of digitally photocorroded (001) GaAs/AlGaAs nanoheterostructures

We report the formation of extraordinary density 16-mercaptohexadecanoic acid (MHDA) self-assembled monolayer (SAMs) on surfaces of freshly etched and re-etched bulk (001) GaAs and on GaAs surfaces of a (001) GaAs/Al0.35Ga0.65 As nanoheterostructure exposed by digital photocorrosion (DIP). Our results demonstrate the advantage of a 2-step thiolation process in achieving high-quality MHDA SAMs on (001) GaAs surfaces. However, the development of the systematically increasing quality SAMs, as suggested by the Fourier-transform infrared absorption (FTIR) data, has been observed on the surfaces of GaAs subsequently revealed by DIP of the GaAs/Al0.35Ga0.65 As nanoheterostructure. An MHDA SAM with the maximum absorbance intensity of the asymmetric -CH2 vibrations, νasym = 2919.6 cm−1, equal to 1.08 × 102 and characterized by the full-width-at-half-maximum of 20.3 cm−1, represents the best quality SAM ever obtained on the surface of (001) GaAs. The underlying mechanism has been explained in terms of the formation of nanostructured surfaces with the increasing concentration of low-coordination number surface atoms available for the interaction with MHDA thiolates. The increased surface density of highly-organized SAMs remains in a qualitative agreement with the proposed cone model of DIP nanostructured surfaces.

Mutual chemical effect of autograft and octacalcium phosphate implantation on enhancing intramembranous bone regeneration

ABSTRACT This study examined the effect of a mixture of octacalcium phosphate (OCP) and autologous bone on bone regeneration in rat calvaria critical-sized defect (CSD). Mechanically mixed OCP and autologous bone granules (OCP+Auto), approximately 500 to 1000 μm in diameter, and each individual material were implanted in rat CSD for 8 weeks, and subjected to X-ray micro-computed tomography (micro-CT), histology, tartrate-resistant acid phosphatase (TRAP) staining, and histomorphometry for bone regeneration. Osteoblastic differentiation from mesenchymal stem cells (D1 cells) was examined in the presence of non-contacting materials by alkaline phosphatase (ALP) activity for 21 days. The material properties and medium composition before and after the incubation were determined by selected area electron diffraction (SAED) under transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), and chemical analysis. The results showed that while bone formation coupled with TRAP-positive osteoclastic resorption and cellular ALP activity were the highest in the Auto group, a positive effect per OCP weight or per autologous bone weight on ALP activity was found. Although the OCP structure was maintained even after the incubation (SAED), micro-deposits were grown on OCP surfaces (TEM). Fibrous tissue was also exposed on the autologous bone surfaces (SEM). Through FT-IR absorption, it was determined that bone mineral-like characteristics of the phosphate group increased in the OCP + Auto group. These findings were interpreted as a structural change from OCP to the apatitic phase, a conclusion supported by the medium degree of saturation changes. The results demonstrate the mutual chemical effect of mixing OCP with autologous bone as an active bone substitute material.

Loss of chemical bonds induced by high doses of γ-radiation in a PADC polymer film: The influence of dose and dose rate on radiation chemical yields

The effects of gamma rays on molecular properties of a poly allyl diglycol carbonate (PADC) polymer, commercially named as CR-39, have been studied. PADC films were exposed to gamma rays at doses ranging from 0.5 to 3 MGy. Gamma exposure induces considerable molecular modifications in PADC films. These modifications were analyzed using Fourier transform infrared (FT-IR) spectroscopy. FT-IR absorption spectra of the gamma irradiated samples show a change in the intensity and the shape of the absorption bands of the chemical groups forming the PADC polymer relative to the pristine one. We have determined G-values for the loss of carbonate ester and ether chemical moieties within PADC. By comparing our G-values with those from other studies, we show that dose rate and dose significantly affect the radiation chemical yields and play an important role of molecular bond kinematics.

The potential of FT-IR spectroscopy for improving healthcare in sepsis – An animal model study

Fourier Transform-Infrared (FT-IR) absorption spectroscopy has been used to investigate pathophysiological changes caused by sepsis. Sepsis has been defined as a potentially fatal organic dysfunction caused by a dysregulated host response to infection and can lead a patient to risk of death. This study used samples consisting of the blood plasma of mice which were induced to sepsis state, compared to a healthy group using FT-IR associated with attenuated total reflectance (ATR) spectroscopy. For statistical analysis, principal components analysis (PCA) and linear discriminant analysis (LDA) were applied, independently, to the second derivative spectra of both the fingerprint (900−1800 cm−1) and the high wavenumber (2800−3100 cm−1) regions. The technique efficiently differentiated the blood plasma of the two groups, sepsis and healthy mice, the analysis indicating that fatty acids and lipids in the blood samples could be an important biomarker of sepsis.

Interplay of vacancies, hydrogen, and electrical compensation in irradiated and annealed n-type β-Ga2O3

Positron annihilation spectroscopy, Fourier transform-infrared absorption spectroscopy, and secondary ion mass spectrometry have been used to study the behavior of gallium vacancy-related defects and hydrogen in deuterium (D) implanted and subsequently annealed β-Ga2O3 single crystals. The data suggest the implantation generates a plethora of VGa-related species, including VGa1- and VGa2-type defects. The latter’s contribution to the positron signal was enhanced after an anneal at 300 °C, which is driven by the passivation of VGaib by hydrogen as seen from infrared measurements. Subsequent annealing near 600 °C returns the positron signal to levels similar to those in the as-received samples, which suggests that split VGa-like defects are still present in the sample. The almost complete removal of the VGaib-2D vibrational line, the appearance of new weak O-D lines in the same spectral region, and the lack of D out-diffusion from the samples suggest that the 600 °C anneal promotes the formation of either D-containing, IR-inactive complexes or defect complexes between VGaib-2D and other implantation-induced defects. The degree of electrical compensation is found to be governed by the interactions between the Ga vacancies and hydrogen.