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Total Reflection Infrared Spectroscopy (total + reflection_infrared_spectroscopy)
Selected AbstractsCatalytic effects of copper oxides on the curing and degradation reactions of cyanate ester resinJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Shinn-Gwo Hong Abstract The catalytic effect of copper oxides on the curing and degradation behaviors of the cyanate ester resin is studied with infrared spectroscopy, attenuated total reflection infrared spectroscopy (ATR), differential scanning calorimetry (DSC), and thermogravimetry analysis (TGA). The result of infrared spectroscopy and DSC analyses indicates that accelerated curing effects from different additives are in the order of zinc octoate > cuprous oxide > cupric oxide. The exothermic characteristics of the cyanate ester resin during cure are drastically affected by the presence of the copper oxides. In addition, it is obtained from TGA analyses that the thermal stability and degradation mechanism of cyanate ester resins are also significantly affected by the addition of copper oxides whereas the extent of degradation from the cupric oxide is greater than that from the cuprous oxide. These results are attributed to the differences in catalytic effects and surface areas of two copper oxides on the cyanate ester resin in contact during the thermal exposure. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 442,448, 2007 [source] Effects of ELF magnetic field on membrane protein structure of living HeLa cells studied by Fourier transform infrared spectroscopyBIOELECTROMAGNETICS, Issue 7 2003Toshitaka Ikehara Abstract The effects of exposure to a 50 Hz magnetic field (maximum of 41.7 to 43.6 mT) on the membrane protein structures of living HeLa cells were studied using attenuated total reflection infrared spectroscopy. One min of such exposure shifted peak absorbance of the amide I band to a smaller wave number, reduced peak absorbance of the amide II band, and increased absorbance at around 1600 cm,1. These results suggest that exposure to the ELF magnetic field has reversible effects on the N,H inplane bending and C,N stretching vibrations of peptide linkages, and changes the secondary structures of ,-helix and ,-sheet in cell membrane proteins. Bioelectromagnetics 24:457,464, 2003. © 2003 Wiley-Liss, Inc. [source] Chirally Modified Platinum Generated by Adsorption of Cinchonidine Ether Derivatives: Towards Uncovering the Chiral SitesCHEMISTRY - A EUROPEAN JOURNAL, Issue 33 2007Norberto Bonalumi Abstract The adsorption behavior of O -methyl and O -trimethylsilyl derivatives of cinchonidine (CD), employed as chiral modifiers for heterogeneous enantioselective hydrogenations on supported Pt catalysts, has been investigated by using attenuated total reflection infrared spectroscopy (ATR-IR) and density functional theory (DFT) electronic structure calculations. The ATR-IR spectroscopic investigation provided detailed insight of the adsorbed modifiers under conditions close to those employed during catalytic processes, and electronic structure calculations were used as a complement to the experiments to uncover the implications of conformational changes in generating the topology of the surface chiral site. The structural investigation of the adsorbed modifiers revealed a relationship between the spatial positions of the ether substituents and the enantiodifferentiation induced by the modified catalyst observed in the hydrogenation of ,-activated ketones. Experiments and calculations corroborate a model, according to which the addition of a bulky ether group to CD reshapes the chiral sites, thus generating catalytic chiral surfaces with different and, in some cases (e.g. hydrogenation of ketopantolactone), even opposite enantioselective properties to those obtained with CD without altering the absolute configuration of the modifier. The study also confirms that active surface conformations of cinchona modifiers are markedly different from those existing in vacuum and in solution, thus underlying the necessity of investigating the surface-modifier interaction in order to understand enantioselectivity. [source] Photoelectrochemical Behavior of Nanostructured WO3 Thin-Film Electrodes: The Oxidation of Formic AcidCHEMPHYSCHEM, Issue 12 2006Damián Monllor-Satoca Abstract Nanostructured tungsten trioxide thin-film electrodes are prepared on conducting glass substrates by either potentiostatic electrodeposition from aqueous solutions of peroxotungstic acid or direct deposition of WO3 slurries. Once treated thermally in air at 450,°C, the electrodes are found to be composed of monoclinic WO3 grains with a particle size around 30,40 nm. The photoelectrochemical behavior of these electrodes in 1,M HClO4 apparently reveals a low degree of electron,hole recombination. Upon addition of formic acid, the electrode showed the current multiplication phenomenon together with a shift of the photocurrent onset potential toward less positive values. Photoelectrochemical experiments devised on the basis of a kinetic model reported recently [I. Mora-Seró, T. Lana-Villarreal, J. Bisquert, A. Pitarch, R. Gómez, P. Salvador, J. Phys. Chem. B2005, 109, 3371] showed that an interfacial mechanism of inelastic, direct hole transfer takes place in the photooxidation of formic acid. This behavior is attributed to the tendency of formic acid molecules to be specifically adsorbed on the WO3 nanoparticles, as evidenced by attenuated total reflection infrared spectroscopy. [source] | ||||||||||