Fourier Transform Infrared Measurements Research Articles

Dislocation creep of dry quartz

AbstractSmall‐scale shear zones within the Permian Truzzo meta‐granite developed during the Alpine orogeny at amphibolite facies conditions. In these shear zones magmatic quartz deformed by dislocation creep and recrystallized dynamically by grain boundary migration with minor subgrain rotation recrystallization to a grain size of around 250–750 µm, consistent with flow at low differential stresses. Fourier transform infrared (FTIR) spectroscopy reveals very low water contents in the interior of recrystallized grains (in the form of discrete OH peaks, ~20 H/106Si and very little broad band absorption, <100 H/106Si). The spectral characteristics are comparable to those of dry Brazil quartz. In FTIR spectra, magmatic quartz grains show a broad absorption band related with high water concentrations only in those areas where fluid inclusions are present while other areas are dry. Drainage of fluid inclusions and synkinematic growth of hydrous minerals indicates that a hydrous fluid has been available during deformation. Loss of intragranular water during grain boundary migration recrystallization did not result in a microstructure indicative of hardening. These FTIR measurements provide the first evidence that quartz with extremely low intragranular water contents can deform in nature by dislocation creep at low differential stresses. Low intragranular water contents in naturally deformed quartz may not be necessarily indicative of a high strength, and the results are contrary to implications taken from deformation experiments where very high water contents are required to allow dislocation creep in quartz. It is suggested that dislocation creep of quartz in the Truzzo meta‐granite is possible to occur at low differential stresses because sufficient amounts of intergranular water ensure a high recovery rate by grain boundary migration while the absence of significant amounts of intragranular water is not crucial at natural conditions.

Green synthesis of gold nanoparticles using aqueous extract of Dillenia indica

In this study, we report a novel method of gold nanoparticle (AuNP) synthesis using aqueous fruit extract of Dillenia indica. The phytochemicals present in the fruit extract act as an effective reducing and capping agent to synthesize AuNPs. The synthesized AuNPs were characterized by spectrophotometry, transmission electron microscopy (TEM), x-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. TEM studies revealed the particles of various sizes and mainly spherical in shape. Selected-area electron diffraction (SAED) patterns and high-resolution transmission electron microscopy (HRTEM) images confirmed the crystallinity of the particles. The XRD patterns showed peaks at (111), (200), (220) which exhibited preferential orientation of the AuNPs as face-centered cubic crystal. FTIR measurements confirmed the coating of phenolic compounds on the AuNPs indicating a possible role of biomolecules for the capping and efficient stabilization of the AuNPs. The synthesized AuNPs did not show any form of cytotoxicity in the normal fibroblast cell line L929.

Evaluating ethane and methane emissions associated with the development of oil and natural gas extraction in North America

Sharp rises in the atmospheric abundance of ethane (C2H6) have been detected from 2009 onwards in the Northern Hemisphere as a result of the unprecedented growth in the exploitation of shale gas and tight oil reservoirs in North America. Using time series of C2H6 total columns derived from ground-based Fourier transform infrared (FTIR) observations made at five selected Network for the Detection of Atmospheric Composition Change sites, we characterize the recent C2H6 evolution and determine growth rates of ∼5% yr−1 at mid-latitudes and of ∼3% yr−1 at remote sites. Results from CAM-chem simulations with the Hemispheric Transport of Air Pollutants, Phase II bottom-up inventory for anthropogenic emissions are found to greatly underestimate the current C2H6 abundances. Doubling global emissions is required to reconcile the simulations and the observations prior to 2009. We further estimate that North American anthropogenic C2H6 emissions have increased from 1.6 Tg yr−1 in 2008 to 2.8 Tg yr−1 in 2014, i.e. by 75% over these six years. We also completed a second simulation with new top-down emissions of C2H6 from North American oil and gas activities, biofuel consumption and biomass burning, inferred from space-borne observations of methane (CH4) from Greenhouse Gases Observing SATellite. In this simulation, GEOS-Chem is able to reproduce FTIR measurements at the mid-latitudinal sites, underscoring the impact of the North American oil and gas development on the current C2H6 abundance. Finally we estimate that the North American oil and gas emissions of CH4, a major greenhouse gas, grew from 20 to 35 Tg yr−1 over the period 2008–2014, in association with the recent C2H6 rise.

Diurnal cycle and multi-decadal trend of formaldehyde in the remote atmosphere near 46° N

Abstract. Only very few long-term records of formaldehyde (HCHO) exist that are suitable for trend analysis. Furthermore, many uncertainties remain as to its diurnal cycle, representing a large short-term variability superimposed on seasonal and inter-annual variations that should be accounted for when comparing ground-based observations to, e.g., model results. In this study, we derive a multi-decadal time series (January 1988–June 2015) of HCHO total columns from ground-based high-resolution Fourier transform infrared (FTIR) solar spectra recorded at the high-altitude station of Jungfraujoch (Swiss Alps, 46.5° N, 8.0° E, 3580 m a. s. l. ), allowing for the characterization of the mid-latitudinal atmosphere for background conditions. First we investigate the HCHO diurnal variation, peaking around noontime and mainly driven by the intra-day insolation modulation and methane (CH4) oxidation. We also characterize quantitatively the diurnal cycles by adjusting a parametric model to the observations, which links the daytime to the HCHO columns according to the monthly intra-day regimes. It is then employed to scale all the individual FTIR measurements on a given daytime in order to remove the effect of the intra-day modulation for improving the trend determination and the comparison with HCHO columns simulated by the state-of-the-art GEOS-Chem v9-02 chemical transport model. Such a parametric model will be useful to scale the Jungfraujoch HCHO columns on satellite overpass times in the framework of future calibration/validation efforts of space-borne sensors. GEOS-Chem sensitivity tests suggest then that the seasonal and inter-annual HCHO column variations above Jungfraujoch are predominantly led by the atmospheric CH4 oxidation, with a maximum contribution of 25 % from the anthropogenic non-methane volatile organic compound precursors during wintertime. Finally, trend analysis of the so-scaled 27-year FTIR time series reveals a long-term evolution of the HCHO columns in the remote troposphere to be related to the atmospheric CH4 fluctuations and the short-term OH variability: +2.9 % year−1 between 1988 and 1995, −3.7 % year−1 over 1996–2002 and +0.8 % year−1 from 2003 onwards.

FT-IR and Raman vibrational spectroscopic studies of R2FeSbO7 (R3+ = Y, Dy, Gd, Bi) pyrochlores

Fourier-transform infrared (FT-IR) and Raman vibrational spectroscopic studies of four iron-antimonate pyrochlores R2FeSbO7 (R3+=Y, Dy, Gd, Bi) are reported for the first time. FT-IR spectra are recorded in the transmission mode in the wavenumbers range of 400–1000cm−1 and Raman spectra are taken in the range of 50–1000cm−1at the room temperature. The vibrational modes are assigned by comparison to the spectra of other pyrochlore structured materials, including the experimental and theoretical (ab initio and lattice-dynamical) calculations found in the literature. This paper provides the assignment of the observed modes which are either fundamental or originated from relaxation of selection rules due to local displacement disorder of R and O′ atoms in R4O′ tetrahedron, and some modes are attributed to the splitting due to different force constants within M(Fe/Sb)−O6 octahedron in all the compounds. Though seven F1u IR modes are usually observed for ideal cubic pyrochlores in the range 100–1000cm−1, we ascribe only four F1u modes in the IR spectra for these samples in the studied wavenumbers range. Six Raman active modes, ΓRaman=A1g+Eg+4F2g, are generally observed in the ideal pyrochlores R2M2O7 in the range 250–800cm−1, but our spectra show twelve Raman bands for each of the samples including only three strong intensity bands, assigned as A1g, Eg, F2g(1), decorated with various shoulders and weak bands. The A1g phonon mode lying in the wavenumbers 511–515cm−1 of the Raman spectra shifts toward the lower wavenumber, as the 48f oxygen x-parameter decreases due to substitution at R-site by large cation from Y→Dy→Gd→Bi. To identify the IR active F1u modes reappearing in the Raman spectra, FT-IR measurement below 400cm−1 is most welcome for these compounds.

Comparing paraffined and deparaffinized breast cancer tissue samples and an analysis of Raman spectroscopy and infrared methods

Breast cancer makes up a quarter of all cancer in women, which is why research into new diagnostic methods and sample preparations need to be developed at an accelerated pace. Researchers are looking for diagnostic tools to detect when an individual has cancer cells and use that information to see what measurements and approaches can be used to take further diagnostic steps. The most common method of sample preparation is the imbibing of tumor tissue in paraffin, which can produce a background for spectroscopic measurements in the range of 500–3500cm−1. In this study we demonstrated that proper preparation of paraffin-embedded specimens and the measurement methodology can eliminate paraffin vibration, as was done in the work Depciuch et al. 2015. Thanks to this spectroscopic technique there may become a reliable and accurate method of diagnosing breast cancer based on the evidence found from the prepared samples.The study compared the results obtained through Raman spectroscopy and FTIR (Fourier Transform Infrared) measurements of healthy and cancerous breast tissues that were either embedded in paraffin or deparaffinized. The resulting spectrum and accurate analysis led to the conclusion that the appropriate measurement of the background and the elimination of peaks from the paraffin had the greatest impact on the reliability of results. Furthermore, after the accurate, detailed studies FTIR and Raman spectroscopy on samples of breast tissue that were deparaffinized or embedded in paraffin, including a complete analysis of the peak after transformation Kramers–Kröning (KK), it was found that sample preparation did not affect the result obtained by measuring the reflectance in the mid-infrared range, and that this only had a minimal effect relating to the intensity obtained by the measurement of the Raman peak. Only in special cases, when Raman spectroscopic methods are used for research to find the peculiarities of the spectra, are deparaffinization recommended, in order to attain more detailed results that could be crucial in understanding the process of carcinogenesis.

Towards understanding the variability in biospheric CO<sub>2</sub> fluxes: using FTIR spectrometry and a chemical transport model to investigate the sources and sinks of carbonyl sulfide and its link to CO<sub>2</sub>

Abstract. Understanding carbon dioxide (CO2) biospheric processes is of great importance because the terrestrial exchange drives the seasonal and interannual variability of CO2 in the atmosphere. Atmospheric inversions based on CO2 concentration measurements alone can only determine net biosphere fluxes, but not differentiate between photosynthesis (uptake) and respiration (production). Carbonyl sulfide (OCS) could provide an important additional constraint: it is also taken up by plants during photosynthesis but not emitted during respiration, and therefore is a potential means to differentiate between these processes. Solar absorption Fourier Transform InfraRed (FTIR) spectrometry allows for the retrievals of the atmospheric concentrations of both CO2 and OCS from measured solar absorption spectra. Here, we investigate co-located and quasi-simultaneous FTIR measurements of OCS and CO2 performed at five selected sites located in the Northern Hemisphere. These measurements are compared to simulations of OCS and CO2 using a chemical transport model (GEOS-Chem). The coupled biospheric fluxes of OCS and CO2 from the simple biosphere model (SiB) are used in the study. The CO2 simulation with SiB fluxes agrees with the measurements well, while the OCS simulation reproduced a weaker drawdown than FTIR measurements at selected sites, and a smaller latitudinal gradient in the Northern Hemisphere during growing season when comparing with HIPPO (HIAPER Pole-to-Pole Observations) data spanning both hemispheres. An offset in the timing of the seasonal cycle minimum between SiB simulation and measurements is also seen. Using OCS as a photosynthesis proxy can help to understand how the biospheric processes are reproduced in models and to further understand the carbon cycle in the real world.

Biosynthesis of Green Nanoparticles fromOccimum sanctumand their Characterization

Development of green nanotechnology is generating interest of researchers toward eco-friendly biosynthesis of nanoparticles. In this present study silver nanoparticles were synthesized from silver nitrate (1mM) through a simple and eco-friendly route using leaf broth of Occimum sanctum as reductant and stabilizer. The silver nanoparticles was synthesized by biological method by exposing the silver ions to leaf broth which were reduced and resulted in the green synthesis of silver nanoparticles ranging from 20nm-30 nm. The bio reduced silver nanoparticles were characterized by UV-Vis spectrophotometer, X-ray diffraction, FESEM with EDAX and Fourier transform infra-red (FTIR) spectroscopy. The synthesised green nanoparticles were subjected to various analytical techniques. The UV absorption range was around 420 nm and the FTIR measurement was carried out to identify the possible biomolecules responsible for efficient stabilization of silver nanoparticles. FESEM determine the shape and size of the nanoparticle which was around 20–30 nm. XRD characterized the structure of crystalline material which showed four different distinct diffraction peaks. Thus, this method can be used for rapid and eco-friendly biosynthesis of stable silver nanoparticles of size range 20–30 nm.

Fourier transform infrared and Raman spectroscopy studies on magnetite/Ag/antibiotic nanocomposites

This article presents a study on the detection of antibiotics in magnetite/Ag/antibiotic nanocomposites using Fourier transform infrared (FTIR) and Raman spectroscopy. Antibiotics with different spectra of antimicrobial activities, including rifampicin, doxycycline, cefotaxime, and ceftriaxone, were studied. Mechanical mixtures of antibiotics and magnetite/Ag nanocomposites, as well as antibiotics and magnetite nanopowder, were investigated in order to identify the origin of FTIR bands. FTIR spectroscopy was found to be an appropriate technique for this task. The spectra of the magnetite/Ag/antibiotic nanocomposites exhibited very weak (for doxycycline, cefotaxime, and ceftriaxone) or even no (for rifampicin) antibiotic bands. This FTIR “invisibility” of antibiotics is ascribed to their adsorbed state. FTIR and Raman measurements show altered CO, CO, and CS bonds, indicating adsorption of the antibiotic molecules on the magnetite/Ag nanocomposite structure. In addition, a potential mechanism through which antibiotic molecules interact with magnetite/Ag nanoparticle surfaces is proposed.

Toronto area ozone: Long‐term measurements and modeled sources of poor air quality events

AbstractThe University of Toronto Atmospheric Observatory and Environment Canada's Centre for Atmospheric Research Experiments each has over a decade of ground‐based Fourier transform infrared (FTIR) spectroscopy measurements in southern Ontario. We present the Toronto area FTIR time series from 2002 to 2013 of two tropospheric trace gases—ozone and carbon monoxide—along with surface in situ measurements taken by government monitoring programs. We interpret their variability with the GEOS‐Chem chemical transport model and determine the atmospheric conditions that cause pollution events in the time series. Our analysis includes a regionally tagged O3 model of the 2004–2007 time period, which quantifies the geographical contributions to Toronto area O3. The important emission types for 15 pollution events are then determined with a high‐resolution adjoint model. Toronto O3, during pollution events, is most sensitive to southern Ontario and U.S. fossil fuel NOx emissions and natural isoprene emissions. The sources of Toronto pollution events are found to be highly variable, and this is demonstrated in four case studies representing local, short‐, middle‐, and long‐range transport scenarios. This suggests that continental‐scale emission reductions could improve air quality in the Toronto region. We also find that abnormally high temperatures and high‐pressure systems are common to all pollution events studied, suggesting that climate change may impact Toronto O3. Finally, we quantitatively compare the sensitivity of the surface and column measurements to anthropogenic NOx emissions and show that they are remarkably similar. This work thus demonstrates the usefulness of FTIR measurements in an urban area to assess air quality.

In situ synthesis of AlN nanoparticles by solid state reaction from plasma assisted ball milling Al and diaminomaleonitrile mixture

In this paper, Aluminum nitride (AlN) nanoparticles from solid state reaction of diaminomaleonitrile (DN) with aluminum (Al) are synthesized by plasma assisted high energy ball milling (p-milling). The structure and morphology of the p-milling products are characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier Transform infra red (FT-IR), Differential scanning calorimetry and Thermal gravimetry (DSC–TG). The XRD results show a correlation between milling time and crystallite size, lattice distortion, specific surface area, and conversion rate of AlN. About 90% AlN has been obtained and specific surface area can reach 52m2g−1 at p-milling 14h. The FT-IR measurements show the solid reaction starts with the deammoniation of DN molecules, followed by the formation of AlN powder as the main solid products after p-milling 8h. The DSC–TG results indicate that DN starts to disintegrate from 180°C to 450°C by the elimination of the N–H and C≡N groups, continue increasing temperature leads to the formation of AlN at 673°C. The activation energy of reaction from p-milling Al and DN mixture is calculated by the Kissinger equation and is about 353.5kJ/mol. Meanwhile, the formation mechanism of AlN in a p-milling process is also investigated.

Physicochemical Biomolecular Insights into Buffalo Milk-Derived Nanovesicles.

Milk is a natural nutraceutical produced by mammals. The nanovesicles of milk play a role in horizontal gene transfer and confer health-benefits to milk consumers. These nanovesicles contain miRNA, mRNA, and proteins which mediate the intercellular communication. In this work, we isolated and characterized the buffalo milk-derived nanovesicles by dynamic light scattering (DLS), nanoparticle tracking analysis (NTA), scanning electron microscopy (SEM), Western probing, and Fourier transform infrared (FTIR) spectroscopy. The DLS data suggested a bimodal size distribution with one mode near 50nm and the other around 200nm for the nanovesicles. The NTA and SEM data also supported the size of nanovesicles within a range of 50-200nm. The FTIR measurements of nanovesicles identified some prominent absorption bands attributable to the proteins (1300-1700cm(-1), amide A and amide B bands), lipids (2800-3100cm(-1)), polysaccharides, and nucleic acids (900-1200cm(-1)). The comparative expression profiles of immune miRNA signatures (miR-15b, miR-21, miR-27b, miR-125b, miR-155, and miR-500) in nanovesicles isolated from milk, serum, and urine revealed that these miRNAs are present abundantly (P < 0.05) in milk-derived nanovesicles. Milk miRNAs (miR-21 and 500) that were also found stable under different household storage conditions indicated that these could be biologically available to milk consumers. Overall, nanovesicles are a new class of bioactive compounds from buffalo milk with high proportion of stable immune miRNAs compared to urine and plasma of same animals.

Effect of storage and drying temperature on the gelation behavior and structural characteristics of sericin

Owing to unique properties, including the wound healing effect, sericin gel and films have attracted significant attention in the biomedical and cosmetic fields. The structural characteristics and properties of sericin gels and films are especially important owing to their effect on the performance of sericin in biomedical and cosmetic applications. In the present study, the effect of temperature on the gelation behavior, gel disruption, and sol–gel transition of sericin was examined using rheometry. In addition, the effect of the drying temperature on the structural characteristics of the sericin film was determined via Fourier transform infrared (FTIR) spectroscopy. The strength of the sericin gel increased and the gelation process was prolonged with decreasing storage temperatures. FTIR and differential scanning calorimetry (DSC) results also revealed that the crystallinity and the thermal decomposition temperature of the sericin film increased with decreasing drying temperature. The sericin gels were disrupted at a storage time of 40min when they were stored at temperatures higher than 50°C, and the corresponding gel strength decreased with increasing temperature. Furthermore, the thermo-reversible nature of gel–sol transition of sericin was confirmed by rheological and FTIR measurements.

Acetylene (C&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;H&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt;) and hydrogen cyanide (HCN) from IASI satellite observations: global distributions, validation, and comparison with model

Abstract. We present global distributions of C2H2 and hydrogen cyanide (HCN) total columns derived from the Infrared Atmospheric Sounding Interferometer (IASI) for the years 2008–2010. These distributions are obtained with a fast method allowing to retrieve C2H2 abundance globally with a 5 % precision and HCN abundance in the tropical (subtropical) belt with a 10 % (25 %) precision. IASI data are compared for validation purposes with ground-based Fourier transform infrared (FTIR) spectrometer measurements at four selected stations. We show that there is an overall agreement between the ground-based and space measurements with correlation coefficients for daily mean measurements ranging from 0.28 to 0.81, depending on the site. Global C2H2 and subtropical HCN abundances retrieved from IASI spectra show the expected seasonality linked to variations in the anthropogenic emissions and seasonal biomass burning activity, as well as exceptional events, and are in good agreement with previous spaceborne studies. Total columns simulated by the Model for Ozone and Related Chemical Tracers, version 4 (MOZART-4) are compared to the ground-based FTIR measurements at the four selected stations. The model is able to capture the seasonality in the two species in most of the cases, with correlation coefficients for daily mean measurements ranging from 0.50 to 0.86, depending on the site. IASI measurements are also compared to the distributions from MOZART-4. Seasonal cycles observed from satellite data are reasonably well reproduced by the model with correlation coefficients ranging from −0.31 to 0.93 for C2H2 daily means, and from 0.09 to 0.86 for HCN daily means, depending on the considered region. However, the anthropogenic (biomass burning) emissions used in the model seem to be overestimated (underestimated), and a negative global mean bias of 1 % (16 %) of the model relative to the satellite observations was found for C2H2 (HCN).

Characterization of Thermal Oxides on 4H Silicon Carbide (4H-SiC) Epitaxial Substrate Using Fourier Transform Infrared Spectroscopy.

We measured the Fourier transform infrared (FT-IR) spectra of thermal oxides with various thicknesses, grown thermally on 4H silicon carbide (4H-SiC) substrates. For the thin (8 nm thick) thermal oxide, the transverse optical (TO) phonon peak frequency in the thermal oxide on the 4H-SiC substrate was observed at ~1080 cm-1 and was higher than that recorded in thermal oxides on a Si substrate (1074 cm-1). This shows that the thin thermal oxide was under compressive stress, calculated to be approximately 0.4 GPa, at the interface between the thermal oxide and 4H-SiC substrate. The shift of the TO phonon for s-polarized light was found to be larger than that for p-polarized light. In contrast, for the thick (85 and 130 nm thick) thermal oxides, the TO phonon peak frequency tended to shift toward lower frequencies with increasing oxide-layer thickness. By comparing the FT-IR and cathodoluminescence (CL) measurements, we conclude that the TO phonon redshift with increasing oxide-layer thickness can mainly be attributed to a corresponding increase in inhomogeneity in the thick thermal oxides.

Investigating Miscibility of Polymers and Its Impact on the Morphology, Thermal, and Mechanical Properties of Polymer Blends

The miscibility of polystyrene (PS)/poly(styrene-co-acrylonitrile) (PSAN) blend films, prepared by the solution casting technique using tetrahydrofuran as a common solvent, was characterized by scanning electron microscopy, differential scanning calorimetry (DSC), thermogravimetry, Fourier transform infrared (FTIR) spectroscopy, and tensile testing. Morphological observations revealed partial miscibility of the blend. FTIR measurements also ascertained partial miscibility of the blend as slight variations in the spectra for various blend compositions were observed. DSC studies also confirmed the semicompatible nature of the examined blend by displaying a single \(T_{\mathrm{g}}\) for the composition, 25/75, and two \(T_{\mathrm{g}}\)’s for compositions, 50/50 and 75/25. The enhancement in thermal stability and mechanical properties which were quite pronounced for the composition, 25/75, also favored partial miscibility of the blend. The partial miscibility of the PS/PSAN blend may be attributed to the intramolecular repulsive effect, characteristic of a homopolymer/copolymer blend system, and the Pi–Pi stacking of phenyl rings of the blend components due to some structural similarities.

Probing the interaction of caffeic acid with ZnO nanoparticles.

The binding of ZnO nanoparticles (NPs) and caffeic acid (CFA) was investigated using fluorescence quenching, UV/vis absorption spectrscopy, Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and dynamic light scattering (DLS) at different temperatures. The study results indicated fluorescence quenching between ZnO NPs and CFA rationalized in terms of a static quenching mechanism or the formation of non-fluorescent CFA-ZnO. From fluorescence quenching spectral analysis, the binding constant (K(a)), number of binding sites (n) and thermodynamic properties were determined. Values of the quenching (K(SV)) and binding (K(a)) constants decrease with increasing temperature and the number of binding sites n = 2. The thermodynamic parameters determined using Van't Hoff equation indicated that binding occurs spontaneously involving the hydrogen bond, and van der Waal's forces played a major role in the reaction of ZnO NPs with CFA. The FTIR, TEM and DLS measurements also indicated differences in the structure, morphology and size of CFA, ZnO NPs and their corresponding CFA-ZnO.

Modified nano Fe2O3-epoxy composite with enhanced mechanical properties

Abstract Epoxy nanocomposite (ENC) reinforced with Fe2O3 nanoparticles (NPs) has been prepared. The surface properties of Fe2O3 NPs were turned using poly(N-vinyl-2-pyrrolidone) (PVP) and (3-aminopropyl) triethoxysilane (APTES) as modified agent. Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA) tests revealed that PVP and APTES have been successfully grafted to the surface of Fe2O3 NPs. The modified Fe2O3 NPs were monodisperse in epoxy matrix as determined using transmission electron microscopy (TEM). FTIR measurements for ENCs indicated that modified Fe2O3 NPs were covalently incorporated into epoxy networks. A disproportionate increase in mechanical properties of the obtained ENCs was observed with the increased modified Fe2O3 NPs loading. When 4 wt.% modified Fe2O3 NPs were introduced, the tensile strength was increased by 50.2% and the fracture toughness, which expressed as stress intensity factor (KIC), was significantly increased by 106% based on single-edge notch bend test.

Physicochemical study of the interaction of lysozyme with surface active ionic liquid 1-butyl-3-methylimidazolium octylsulfate [BMIM] [OS] in aqueous and buffer media

Abstract The interactions of the surface active ionic liquid (IL), 1-butyl-3-methylimidazolium octylsulfate [BMIM] [OS], with lysozyme were studied using tensiometry, turbidimetry, absorbance, fluorescence spectra, circular dichroism (CD), and Fourier transformed infra red (FTIR) techniques in phosphate buffer medium (pH 6 and 8) at 298 K. In the studied media coacervate was formed and the coacervation process depended on protein concentration. Isoemissive points were observed in emission spectra of lysozyme with IL. The isoemissive wavelength depended on the pH of the solution and also on [lysozyme]. The denaturation of lysozyme depended on the medium pH and the added [IL] as revealed from the CD and FTIR measurements. Molecular docking has provided information of the region of the lysozyme surface where the IL started to bind with it.

The loading effect of silver nanoparticles prepared by impregnation and solution plasma methods on the photocatalysis of Ga2O3

Ag loaded Ga2O3 (Ag/Ga2O3) photocatalysts for the reduction of CO2 with water have been prepared by impregnation (IMP) and two types of solution plasma methods (SPM1 and SPM2). Using X-ray absorption near edge structure (XANES) and Fourier transform infrared (FT-IR) spectroscopies, we have investigated the local electronic structures of Ag/Ga2O3 photocatalysts as well as the adsorption behaviors of CO2 during the reaction. Both Ag L3-edge and O K-edge XANES analyses reveal the Ag–Ga2O3 interaction, i.e., the charge-transfer from O atoms to Ag atoms, by demonstrating the decrease in the unoccupied Ag 4d-state density and increase in the unoccupied O 2p-state density. The strength of the interaction depends on the preparation method, and increases in the order of Ag/Ga2O3 (SPM2), Ag/Ga2O3 (SPM1) and Ag/Ga2O3 (IMP). In addition, FT-IR measurements have disclosed that Ag/Ga2O3 (IMP) obtains a larger amount of strongly basic sites as a result of the strongest interaction between Ag and Ga2O3. Although the amount of the adsorbed CO2 is different in each Ag/Ga2O3 sample, in the following formation process of bidentate formate species, no remarkable difference is detected among all samples. The bidentate formate species are likely to interact with H2O molecules to produce CO under photoirradiation, and this process would be affected by the strength of the Ag–Ga2O3 interaction, because this reaction hardly proceeds over Ag/Ga2O3 (SPM2) having the weakest Ag–Ga2O3 interaction.