Fourier transform-Raman Research Articles

Dietary Fiber-Induced Changes in the Structure and Thermal Properties of Gluten Proteins Studied by Fourier Transform-Raman Spectroscopy and Thermogravimetry.

Interactions between gluten proteins and dietary fiber supplements at the stage of bread dough formation are crucial in the baking industry. The dietary fiber additives are regarded as a source of polysaccharides and antioxidants, which have positive effects on human health. The fiber enrichment of bread causes a significant reduction in its quality, which is connected with changes in the structure of gluten proteins. Changes in the structure of gluten proteins and their thermal properties induced by seven commercial dietary fibers (fruit, vegetable, and cereal) were studied by FT-Raman spectroscopy and thermogravimetry (TGA), respectively. For this aim the bread dough at 500 FU consistency was made of a blend of wheat starch and wheat gluten as well as the fiber, the content of which ranged from 3 to 18% w/w. The obtained results revealed that all dietary fibers apart from oat caused similar changes in the secondary structure of gluten proteins. The most noticeable changes were observed in the regions connected with hydrogen-bonded β-sheets (1614 and 1684 cm(-1)) and β-turns (1640 and 1657 cm(-1)). Other changes observed in the gluten structure, concerning other β-structures, conformation of disulfide bridges, and aromatic amino acid microenvironment, depend on the fibers' chemical composition. The results concerning structural changes suggested that the observed formation of hydrogen bonds in the β-structures can be connected with aggregation or abnormal folding. This hypothesis was confirmed by thermogravimetric results. Changes in weight loss indicated the formation of a more complex and strong gluten network.

Different level of fluorescence in Raman spectra of montmorillonites

The paper presents the study of selected montmorillonite standards by Raman spectroscopy and microscopy supported by elemental analysis, X-ray powder diffraction analysis and thermal analysis. Dispersive Raman spectroscopy with excitation lasers of 532nm and 780nm, dispersive Raman microscopy with excitation laser of 532nm and 100× magnifying lens, and Fourier Transform-Raman spectroscopy with excitation laser of 1064nm were used for the analysis of four montmorillonites (Kunipia-F, SWy-2, STx-1b and SAz-2). These mineral standards differed mainly in the type of interlayer cation and substitution of octahedral aluminium by magnesium or iron. A comparison of measured Raman spectra of montmorillonite with regard to their level of fluorescence and the presence of characteristic spectral bands was carried out. Almost all measured spectra of montmorillonites were significantly affected by fluorescence and only one sample was influenced by fluorescence slightly or not at all. In the spectra of tested montmorillonites, several characteristic Raman bands were found. The most intensive band at 96cm−1 belongs to deformation vibrations of interlayer cations. The band at 200cm−1 corresponds to deformation vibrations of the AlO6 octahedron and at 710cm−1 can be assigned to deformation vibrations of the SiO4 tetrahedron. The band at 3620cm−1 corresponds to the stretching vibration of structural OH groups in montmorillonites.

Influence of organic dopants on the optical properties of 4-N,N′-dimethylamino-N′-methyl stilbazolium tosylate crystals

Organic crystals of 4-N,N′-dimethylamino-N′-methyl stilbazolium tosylate (DAST), 2-amino-5-nitro pyridinium (2A5NP) and 2-amino-5-nitro pyridine toluene sulfonate (2A5NPTS) doped DAST crystals were grown by slow cooling method. The powder samples were examined by X-ray diffraction to estimate the lattice parameter values of the crystals. Fourier Transform Infra-Red (FT-IR) and Fourier Transform-Raman (FT-Raman) spectroscopic studies were performed to identify the various functional groups associated with the crystals. The four strong vibrational modes were observed at 1161cm−1, 1181cm−1, 1346cm−1 and 1577cm−1 contributing to linear electro-optic effect in DAST crystals. The Density Functional Theory (DFT) was used for FT-IR and FT-Raman analysis by means of the hybrid functional DFT/B3LYP with 6-311 G (d, p) basis set. The optical band-gaps were calculated from the UV–vis and photoluminescence spectra of pure and doped DAST samples.

Preparation and characterization of monodisperse polystyrene-silica nanocomposites

Polystyrene-silica nanocomposites were successfully prepared by UV-induced graft polymerization of styrene onto a silica surface. Composites were prepared by batch and continuous-circulation reactions, and results indicated that polystyrene was successfully grafted onto inorganic silica particles for both reactions. Scanning electron microscopy and thermogravimetry analyses of the composites indicated 45% volume increase and 37% polymer content after an optimal reaction time of 30 minutes, respectively, for the batch reaction. For the continuous-circulation reaction, the corresponding results were 63% volume increase and 42% polymer content after 140 min of reaction time. Fourier Transform-Raman spectroscopy analysis of composites showed the characteristic peaks of both silica and polystyrene thus confirming the successful graft-polymerization for both reactions. Disappearance of C-H and C=C ring stretching bands at 3070 and 1578 cm-1 in composites after their optimal reaction times for both reactions indicated a possible ring opening mechanism due to prolonged exposal to the UV light source. For the batch reaction, composites showed new vibration bands at 1052 and 812 cm-1 for asymmetric and symmetric Si-O-C stretching, respectively, indicating a covalent bond between the grafted polymer and silica surface. X-Ray photoelectron spectroscopy (XPS) analysis showed an increase in the elemental concentration of carbon from 5 to 46% for 30 minute composites in batch reaction. XPS analysis also indicated that the relative OH group content of the surface of the silica particles determines the effectiveness of the graft-polymerization of styrene. Open image in new window

Infrared and Raman spectroscopic methods for characterization of Taxus baccata L. – Improved taxane isolation by accelerated quality control and process surveillance

Different yew species contain poisonous taxane alkaloids which serve as resources for semi-synthesis of anticancer drugs. The highly variable amounts of taxanes demand new methods for fast characterization of the raw plant material and the isolation of the target structures during phyto extraction. For that purpose, applicability of different vibrational spectroscopy methods in goods receipt of raw plant material and in process control was investigated and demonstrated in online tracking isolation and purification of the target taxane 10-deacetylbaccatin III (10-DAB) during solvent extraction. Applying near (NIRS) and mid infrared spectroscopy (IRS) the amount of botanical impurities in mixed samples of two different yew species (R2=0.993), the leave-to-wood ratio for Taxus baccata material (R2=0.94) and moisture in dried yew needles (R2=0.997) can be quantified. By partial least square analysis (PCA) needles of different Coniferales species were successfully discriminated by Attenuated Total Reflectance-Fourier-Transform Infrared Spectroscopy (ATR-FT-IR). The analytical potential of ATR-FT-IR and Fourier Transform-Raman Spectroscopy (FT-RS) in process control of extraction and purification of taxanes is demonstrated for determination of the water content in methanolic yew extracts (R2=0.999) and for quantification of 10-DAB (R2=0.98) on a highly sophisticated level. The decrease of 10-DAB in the plant tissue during extraction was successfully visualized by FT-IR imaging of thin cross sections providing new perspectives for process control and design.

Size controlled biogenic silver nanoparticles as antibacterial agent against isolates from HIV infected patients

Silver nanoparticles (AgNPs) are synthesized using biological sources due to its high specificity in biomedical applications. Herein, we report the size and shape controlled synthesis of AgNPs using the aqueous extract of blue green alga, Spirulina platensis. Size, shape and elemental composition of AgNPs were characterized using UV–vis spectroscopy, Fluorescence spectroscopy, FT-IR (Fourier Transform-Infrared Spectroscopy), FT-RS (Fourier Transform-Raman Spectroscopy), SEM–EDAX (Scanning Electron Microscopy–Energy Dispersive X-ray analysis) and HR-TEM (High Resolution Transmission Electron Microscopy). AgNPs were stable, well defined and monodispersed (spherical) with an average size of 6nm. The synthesized AgNPs were tested for its antibacterial potency against isolates obtained from HIV patients.

Effect of Neodymium on Optical Bandgap and Microwave Dielectric Properties of Barium Zirconate Ceramic

The ceramics with general formula Ba(1−x) Nd(2x/3)ZrO3 (x = 0.0,0.02, 0.04, 0.06, 0.08, and 0.1) were prepared by solid-state reaction. The phase formation of the powders was analyzed by means of X-ray diffraction (XRD), Fourier transform-Raman (FT-Raman), and Fourier transform infrared (FTIR) spectroscopy. XRD patterns revealed that all powders show a perovskite-type cubic structure with space group Pm-3m. FT-Raman and FTIR spectra suggested the formation of higher degree of symmetry in the crystal. The optical bandgap was found to be decreasing while Urbach energy was found to be increasing with an increase of Nd3+ content. The surface morphology of sintered pellets was studied by scanning electron microscope. Microwave dielectric constant and quality factor were investigated by the TE01δ mode dielectric resonator method. The microwave dielectric constant and temperature coefficient of resonant frequency decreases with increase in of Nd3+ content. The irregular nature of quality factor (Q × f) was observed due to the extrinsic losses in materials. The dielectric resonator antenna (DRA) characteristics were investigated experimentally and numerically using a monopole antenna through an infinite ground plane and Ansoft’s high-frequency structure simulator software, respectively. The resonant frequency and bandwidth of DRAs were also investigated for the ceramics.

Normal co-ordinate analysis, molecular structural, non-linear optical, second order perturbation studies of Tizanidine by density functional theory

The spectroscopic techniques and semi-empirical molecular calculations have been utilized to analyze the drug Tizanidine (5CDIBTA). The solid phase Fourier Transform Infrared (FTIR) and Fourier Transform Raman (FTR) spectral analysis of 5CDIBTA is carried out along with density functional theory (DFT) calculations (B3LYP) with the 6-311++G(d,p) basis set. Detailed interpretation of the vibrational spectra of the compound has been made on the basis of the calculated potential energy distribution (PED). The individual atomic charges by NPA using B3LYP method is studied. A study on the Mulliken atomic charges, frontier molecular orbitals (HOMO–LUMO), molecular electrostatic potential (MEP) and thermodynamic properties were performed. The electric dipole moment (μ) and the first hyperpolarizability (α) values of the investigated molecule were also computed.

Conformation, molecular structure, and vibrational assignment of bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II)

Conformational analysis, molecular structure, relative stability, and complete vibrational assignment of bis(2,2,6,6-tetramethylheptane-3,5-dionato)copper(II), Cu(tmhd)2, were investigated by density functional theory (DFT), Natural Bond Orbital (NBO) theory and Atoms-in-Molecules (AIM) analysis. Fourier transform-Raman and IR spectra of this complex have been also recorded. The theoretical and experimental methods used to investigate the substitution effects of methyl groups by t-butyl (t-but) on the structure and stability of complex. To explore the substitution effects, the structure and vibrational spectra of Cu(tmhd)2 compared with copper(II) acetylacetonate, Cu(acac)2. A complete assignment of the observed band frequencies has been done. Comparing of observed and calculated vibrational spectra suggests coexisting of two conformers in the sample. All theoretical and vibrational spectroscopic results are consisting with a stronger metal–oxygen bond in Cu(tmhd)2 than in Cu(acac)2.

Chemical synthesis of α-La2S3 thin film as an advanced electrode material for supercapacitor application

α-La2S3 thin films have been synthesized for the first time by successive ionic layer adsorption and reaction (SILAR) method and used for supercapacitor application. These films are characterized for crystal structure, surface morphology and wettability studies using X-ray diffraction (XRD), Fourier Transform-Raman (FT-Raman) spectroscopy, scanning electron microscopy (SEM) and contact angle measurements. The electrochemical supercapacitive performance of α-La2S3 electrode is evaluated by cyclic voltammetry (CV), galvanostatic charge discharge (GCD) and electrochemical impedance spectroscopy (EIS) techniques. From the electrochemical study, it is seen that α-La2S3 electrode delivers high specific capacitance of 256Fg−1 at scan rate of 5mVs−1 with cycling stability of 85% over 1000 cycles. Such La2S3 electrode has great application in supercapacitor device for energy storage.

Polyaniline based electrodes for electrochemical supercapacitor: Synergistic effect of silver, activated carbon and polyaniline

The composite thin films of Silver–activated carbon/polyaniline (Ag–AC/PANI) have been deposited on stainless steel substrates by a facile dip coating technique. The formation of Ag–AC/PANI electrode is analyzed by Fourier transform infrared, Fourier transform-Raman and X-ray photoelectron spectroscopy techniques. Field Emission Scanning Electron Microscopy revealed the presence of Ag nanoparticles on the porous spongy background of PANI. The highest specific capacitance of 567Fg−1at 5mVs−1 and energy density of 86.30Whkg−1 at 1mAcm−2 is observed for the Ag–AC/PANI indicating positive synergistic effect of silver, activated carbon and PANI. In which silver nanoparticles help in improving the electronic conductivity and activated carbon enhances the electrochemical stability of the PANI electrodes.

Comparison of Physicochemical Surface Conditioning Methods for Adhesion of bis-GMA Resin Cement to Particulate Filler Composite and Surface Characterization

This study compared the effect of physicochemical surface conditioning methods on the adhesion of bis-GMA-based resin cement to particulate filler composite (PFC) used for indirect dental restorations. PFC blocks (N block = 54, n block = 9 per group) were polymerized and randomly subjected to one of the following surface conditioning methods: a) No conditioning (Control-C), b) Hydrofluoric acid (HF)etching for 60 s (AE60), c) HF for 90 s (AE90), d) HF for 120 s (AE120), e) HF for 180 s (AE180), and f) air-abrasion with 30 µm silica-coated alumina particles (AB). The conditioned surfaces were silanized with an MPS silane, and an adhesive resin was applied. Resin composite blocks were bonded to PFC using resin cement and photo-polymerized. PFC–cement–resin composite blocks were cut under coolant water to obtain bar specimens (1 mm × 0.8 mm). Microtensile bond strength test (μTBS)was performed in a universal testing machine (1 mm/min). After debonding, failure modes were classified using stereomicroscopy. Surface characterization was performed on a set of separate specimen surfaces using Scanning Electron Microscopy (SEM), X-Ray Dispersive Spectroscopy (XDS), X-Ray Photoelectron Spectroscopy (XPS), and Fourier Transform-Raman Spectroscopy (FT-RS). Mean μTBS (MPa) of C (35.6 ± 4.9) was significantly lower than those of other groups (40.2 ± 5.6–47.4 ± 6.1) (p < 0.05). The highest μTBS was obtained in Group AB (47.4 ± 6.1). Prolonged duration of HF etching increased the results (AE180: 41.9 ± 7), but was not significantly different than that of AB (p > 0.05). Failure types were predominantly cohesive in PFC (34 out of 54) followed by cohesive failure in the cement (16 out of 54). Degree of conversion (DC) of the PFC was 63 ± 10%. SEM analysis showed increased irregularities on PFC surfaces with the increased etching time. Chemical surface analyses with XPS and FT-RS indicated 11–70% silane on the PFC surfaces that contributed to improved bond strength compared to Group C that presented 5% silane, which seemed to be a threshold. Group AB displayed 83% SiO2 and 17% silane on the surfaces.

Konjac glucomannan-induced changes in thiol/disulphide exchange and gluten conformation upon dough mixing

Effects of konjac glucomannan (KGM) on the changes in gluten upon dough mixing were investigated in this study. Wheat flour was blended with KGM and processed into dough. Farinographic analysis showed that KGM caused a significant increase in water absorption and dough development time to reach maximum consistency. Comparison of electrophoretic protein profile from control dough and KGM-dough revealed that protein fractions were similar in molecular size distribution, but the lability of glutenin aggregates slightly differed. Addition of KGM to gluten induced negative effects on exchange between sulfhydryl groups and disulphide bonds. Fourier transform-Raman spectroscopy indicated that secondary structure of gluten proteins was differentially modified related with water absorption of flours before dough formation. This study reveals that when KGM is added to the dough, conformational behaviours of gluten proteins are changed and the hydroxyl groups of KGM might be involved in the interaction by forming strong intermolecular hydrogen bonding system.

Effect of bismuth doping on the ZnO nanocomposite material and study of its photocatalytic activity under UV-light

Bismuth (Bi)-doped ZnO nanocomposite material was prepared by precipitation method with doping precursors of bismuth nitrate pentahydrate and oxalic acid, characterized by X-ray diffraction (XRD), High Resolution-Scanning Electron Microscopy (HR-SEM) with Energy Dispersive X-ray (EDX) analysis, UV–visible Diffuse Reflectance Spectroscopy (UV–visible DRS) and Fourier Transform-Raman (FT-RAMAN) analysis. The enhanced photocatalytic activity of the Bi-doped ZnO is demonstrated through photodegradation of Congo red under UV-light irradiation. The mechanism of photocatalytic effect of Bi-doped ZnO nanocomposite material has been discussed.

Chemical composition and binary mixture of human urinary stones using FT-Raman spectroscopy method

In the present study the human urinary stones were observed in their different chemical compositions of calcium oxalate monohydrate, calcium oxalate dihydrate, calcium phosphate, struvite (magnesium ammonium phosphate), uric acid, cystine, oxammite (ammonium oxalate monohydrate), natroxalate (sodium oxalate), glushinkite (magnesium oxalate dihydrate) and moolooite (copper oxalate) were analyzed using Fourier Transform-Raman (FT-Raman) spectroscopy. For the quantitative analysis, various human urinary stone samples are used for ratios calculation of binary mixtures compositions such as COM/COD, HAP/COD, HAP/COD, Uric acid/COM, uric acid/COD and uric acid/HAP. The calibration curve is used for further analysis of binary mixture of human urinary stones. For the binary mixture calculation the various intensities bands at 1462cm−1 (ICOM), 1473cm−1 (ICOD), 961cm−1 (IHAP) and 1282cm−1 (IUA) were used.

Electrochemical supercapacitor electrode material based on polyacrylic acid/polypyrrole/silver composite

In the present work, we have synthesized polypyrrole (PPY)/polyacrylic acid (PAA)/silver (Ag) composite electrodes by chemical polymerization via a simple and cost effective dip coating technique for supercapacitor application. Fourier transform-infrared, Fourier transform-Raman, X-ray photoelectron and energy dispersive X-ray spectroscopy techniques are used for the phase identification. Surface morphology of the films is examined by field emission scanning electron microscopy, which revealed granular structure for PPY, spherical interlaced granules for PPY/PAA and granules with bright spots of Ag nanoparticles for the PPY/PAA/Ag composites. The supercapacitive behavior of the electrodes is tested in three electrode system with 0.1M H2SO4 electrolyte by using cyclic voltammetery and charge discharge test. The highest specific capacitance 226Fg−1 at 10mVs−1 and energy density of 17.45Whkg−1 at 0.5mAcm−2 is obtained for the PPY/PAA/Ag composite electrodes. Present work demonstrates an easy way of improving specific capacitance of the polymer electrodes. Thus the work will open a new avenue for designing low cost high performance devices for better supercapacitors.

Characterization of ZSM-5 modified with niobium pentoxide: the study of thiophene adsorption

ZSM-5 adsorbents impregnated with Nb2O5 were applied in the sulfur removal in the form of thiophene, refractory substance of difficult removal of liquid fuels. For this purpose, a model fuel containing iso-octane contaminated with thiophene in concentrations of 877.5 to 1155 ppmw was prepared. The samples were characterized by X-ray diffractometry (XRD), Fourier transform infrared (FTIR) and Fourier transform-Raman (FT-Raman) spectroscopies for confirmation of the adsorbents, being prioritized the adsorption study with that containing 5 wt.% of niobium pentoxide, because it showed a greater capacity for removal of thiophene. The best results of adsorption were achieved at 353 K, a longer time to reach equilibrium was observed. Under these conditions, the best kinetic fitting was achieved using the equation of pseudo-second order, demonstrating the domain of the phenomenon of chemisorption. While under lower temperatures, the diffusion model presented a better approximation of the experimental results. Also, the increasing of temperature did enhance spontaneous processes.

Molecular structure, vibrational spectra, first order hyper polarizability, NBO and HOMO–LUMO analysis of 4-amino-3(4-chlorophenyl) butanoic acid

The Fourier transform infrared (FT-IR) and Fourier transform Raman (FTR) spectra of 4-amino-3(4-chlorophenyl) butanoic acid were recorded in the regions 4000–400 cm−1 and 4000–100 cm−1, respectively, in the solid phase. Molecular electronic energy, geometrical structure, harmonic vibrational spectra, infrared intensities and Raman scattering activities, highest occupied molecular orbital, lowest unoccupied molecular orbital energy, energy gaps and thermodynamical properties such as zero-point vibrational energies, rotational constants, entropies and dipole moment were computed at the Hartree–Fock/6-31G(d,p) and three parameter hybrid functional Lee–Yang–Parr/6-31G(d,p) levels of theory. The vibrational studies were interpreted in terms of potential energy distribution (PED). The results were compared with experimental values with the help of scaling procedures. Most of the modes have wave numbers in the expected range and are in good agreement with computed values. The first order hyperpolarizability (βtotal) of this molecular system and related properties (β, μ, 〈α〉 and Δα) are calculated using HF/6-31G(d,p) and B3LYP/6-31G(d,p) methods based on the finite-field approach. Stability of the molecule arising from hyperconjugative interactions, charge delocalization and intramolecular hydrogen bond-like weak interaction has been analyzed using natural bond orbital (NBO) analysis by using B3LYP/6-31G(d,p) method. The results show that electron density (ED) in the σ∗ and π∗ antibonding orbitals and second-order delocalization energies E(2) confirm the occurrence of intramolecular charge transfer (ICT) within the molecule.

Novel synthesis of kesterite Cu2ZnSnS4 nanoflakes by successive ionic layer adsorption and reaction technique: Characterization and application

Novel nanoflakes of Cu2ZnSnS4 (CZTS) thin film were directly deposited on fluorine doped tin oxide (FTO)-coated glass substrates by the successive ionic layer adsorption and reaction (SILAR) method. The results of energy dispersive X-ray spectroscopy (EDX) indicate that these CZTS thin films are Cu rich and S poor. The combination of X-ray diffraction (XRD) results and Fourier Transform-Raman (FT-Raman) spectroscopy reveal that these thin films exhibit a strong preferential orientation of flakes along the [112] direction and that a small Cu2−xS phase exists in CZTS thin films. Photoelectrochemical characterization revealed a p-type photo-response when the films were illuminated in an aqueous Eu3+ redox electrolyte. The total conversion power of the CZTS cell is 1.85% under 30mW/cm2 illumination.

Density functional theory and ab initio studies of vibrational spectra of 2-bis (2-chloroethyl) aminoperhydro-1,3,2-oxazaphosphorinane-2-oxide

The Fourier transform Raman (FTR) and Fourier transform infrared (FTIR) spectra of 2-bis (2-chloroethyl) aminoperhydro-1,3,2-oxazaphosphorinane-2-oxide were recorded in the regions 4000–100 cm− 1 and 4000–400 cm1, respectively, in the solid phase. Molecular electronic energy, geometrical structure, harmonic vibrational spectra, infrared intensities and Raman scattering activities, highest occupied molecular orbital, lowest unoccupied molecular orbital energy, energy gaps and thermodynamical properties such as zero-point vibrational energies, rotational constants, entropies and dipole moment were computed at the Hartree–Fock/6-31G(d,p) and three parameter hybrid functional Lee–Yang–Parr/6-31G(d,p) levels of theory. The vibrational studies were interpreted in terms of potential energy distribution. The results were compared with experimental values with the help of scaling procedures. The observed wave number in FTIR and FTR spectra was analysed and assigned to different normal modes of the molecule. Most of the modes have wave numbers in the expected range and are in good agreement with computed values.