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161.
A new force field for dimethyl ether (DME) based on the Lennard-Jones (LJ) 12-6 plus point charge functional form is presented in this work. This force field reproduces experimental saturated liquid and vapor densities, vapor pressures, heats of vaporization, and critical properties to within the statistical uncertainty of the combined experimental and simulation measurements for temperatures between the normal boiling and critical point. Critical parameters and normal boiling point are predicted to within 0.1% of experiment. This force field is used in grand canonical histogram reweighting Monte Carlo simulations to predict the pressure composition diagrams for the binary mixtures DME + SO(2) at 363.15 K and DME + CO(2) at 335.15 and 308.15 K. For the DME + SO(2) mixture, simulation is able to qualitatively reproduce the minimum pressure azeotropy observed experimentally for this mixture, but quantitative errors exist, suggesting that multibody effects may be important in this system. For the DME + CO(2) mixture, simulation is able to predict the pressure-composition behavior within 1% of experimental data. Simulations in the isobaric-isothermal ensemble are used to determine the microstructure of DME + SO(2) and DME + CO(2) mixtures. The DME + SO(2) shows weak pairing between DME and SO(2) molecules, while no specific pairing or aggregation is observed for mixtures of DME + CO(2). 相似文献
162.
Anupama Kamath Vidyanand K. Revankar 《Journal of inclusion phenomena and macrocyclic chemistry》2012,72(1-2):149-155
Novel CoII, NiII, CuII and ZnII complexes of the polynucleating oxaza macrocyclic ligand (LH4) derived from the 2:2 condensation of pyrazole-3,5-dicarbohydrazide and 2,6-diformyl-4-methylphenol have been synthesized. Ligand and complexes were characterized on the basis of elemental analysis, IR, 1HNMR, UV–Visible, magnetic susceptibility, ESR and conductivity measurements, FAB-mass and thermal analysis. Present ZnII and CuII complexes are binuclear in nature with octahedral geometry, where as CoII and NiII complexes are tetranuclear with square-planar geometry. CuII and CoII complexes are paramagnetic whereas ZnII and NiII complexes are diamagnetic. Only the copper complex has shown redox property in the applied potential range while the ligand and other complexes are found to be electrochemically innocent. 相似文献
163.
Samiul Hoque Narendra Nath Dass Krishna Gopal Bhattacharyya 《Molecular Crystals and Liquid Crystals》2014,592(1):149-162
Poly(cholesterylacrylatesulfone) (PCHAS) and poly(cholesterylacrylatesulfone-co-1-hexene)s (PCHASHs) at different ratios are synthesized from the monomer cholesteryl acrylate. The liquid crystalline phases are observed under a hot stage fitted with a polarizing optical microscope. The polysulfone and copolysulfones are characterized by FT-IR, 1H-NMR, DSC, and TGA techniques. From SEM (EDX) the qualitative amounts of elemental sulfur found in PCHAS and PCHASH11 are 2.90 weights (%) and 4.39 weights (%), respectively. The GPC data using THF as the solvent shows that the number average molecular weight of the PCHAS is 5268 g/mol and the molecular weights of the PCHASHs are higher than the PCHAS. 相似文献
164.
Kaustava Bhattacharyya Arvind K. Tripathi Narendra M. Gupta Avesh K. Tyagi 《Photochemistry and photobiology》2010,86(2):241-246
Titania supported on polyester fabric (TiO2–PY) with varying titania loadings (2–7 wt%) were prepared via the dip-coating method at room temperature using an aqueous slurry of anatase titania. Structural and morphological characterizations by X-ray diffraction and scanning electron microscopy revealed that the titanium dioxide crystallites deposited on the surface of the polyester fabric were in the micrometer range while their phase remained to be anatase. Photocatalytic activity of TiO2–PY fabric catalysts was evaluated for vapor-phase oxidation of methanol in air as a test reaction in the presence of UV as well as solar radiation under ambient conditions. These catalysts were found to be quite active in both UV and solar irradiation with activity being higher in the former case. CO2 yield from photo-oxidation of methanol depended on titania content and also on its dispersion over polyester fabric support. 相似文献
165.
Mukesh Kumar Atal Veena Dhayal Meena Nagar Rakesh Bohra Kuldeep S. Rathore Narendra S. Saxena 《Journal of Sol-Gel Science and Technology》2010,53(1):67-78
Reaction of [VO(OPr i )3] (1) with [O(CH2CH2OH)2] in 1:1 molar ratio in anhydrous benzene yield glycol-modified precursor, [VO{OCH2CH2OCH2CH2O}{OPr i }] (2). Further reactions of (2) with internally functionalized oximes in anhydrous benzene yield heteroleptic complexes of the type [VO{OCH2CH2OCH2CH2O}{ON=C(R)(Ar)}] (3–8) {where R=CH3, Ar=C4H3O-2 (3), C4H3S-2 (4), C5H4N-2 (5); and when R=H, Ar=C4H3O-2 (6), C4H3S-2 (7), C5H4N-2 (8)}. All these derivatives have been characterized by elemental analyses, molecular weight measurements and spectroscopic techniques. The crysoscopic molecular weight measurement as well as FAB mass study suggests dimeric nature of (2). However, FAB mass spectrum of (4), and the crysoscopic molecular weight measurements of (3), (4), (5) and (6) indicate the monomeric behavior of the oximato derivatives (3–8). Hexa-coordination around vanadium(V) has been proposed for both monomeric and dimeric derivatives. Sol–gel transformations of (1), (2) or (4) to vanadia [(a), (b) or (c), respectively] have been carried out at low sintering temperature (600 °C). The XRD patterns of (a), (b) or (c) indicate formation of a single orthorhombic phase in all the three cases. The SEM images suggest grain like [for (a) and (b)] and rod like [for (c)] morphology of the crystallites. IR, Raman spectra as well as EDX analyses indicate formation of pure vanadia. Absorption spectra of the vanadia (b) and (c) suggest energy band gaps of 2.53 and 2.65 eV, respectively. 相似文献
166.
Kamlesh Kumari Prashant Singh Monica Dubey Narendra D. Pandey Ramesh Chandra Gopal K. Mehrotra 《Comptes Rendus Chimie》2012,15(4):267-272
Herein, we report a simple, convenient and catalyst free one-pot synthesis of chromenothiazolone analogues via multicomponent reaction between thiazolidine-2,4-dione, aromatic aldehyde and phenol. This reaction proceeded smoothly in good to excellent yields and offered several other advantages including short reaction time, simple experimental workup procedure and no byproduct. 相似文献
167.
Belavalli E. Prasad P. Vishnu Kamath S. Ranganath 《Journal of Solid State Electrochemistry》2012,16(12):3715-3722
Cathodic reduction of zinc nitrate solution results in the deposition of ZnO crystallites with a strong c-axis orientation. The orientation of crystallites can be switched to 10l (l?=?1, 2, 3) direction by varying the bath concentration (0.04–0.1?M) and the deposition conditions (T, 50–70?°C; t, 30–90?min). The range of concentrations yielding c-axis orientation can be widened at a high deposition temperature. At 0.1?M bath concentration and long deposition times, crystallites are oriented along 10l (l?=?3) direction. At low temperature (50?°C), 100 oriented nanostructured ZnO coatings are obtained (crystallite size, 20–35?nm). The c-axis-oriented crystallites grow as hexagonal columns perpendicular to substrate and 10l-oriented crystallites grow tilted at different angles to the substrate surface. 相似文献
168.
169.
Kubicka D Kumar N Venäläinen T Karhu H Kubicková I Osterholm H Murzin DY 《The journal of physical chemistry. B》2006,110(10):4937-4946
The metal-support interactions on a series of catalysts of different acidities, including platinum-modified zeolites and H-MCM-41, are investigated by means of XPS, CO and pyridine adsorption, and a model reaction (ring opening of decalin). The electronic properties of Pt are influenced by the acidity of the support, and the alteration of Pt properties increases with increasing acidity of the support, as can be seen from the changes in the Pt binding energy and stretching frequency of adsorbed CO. At the same time, the presence of platinum affects the acidic properties of the supports by reducing the strength of the acid sites. This is observed directly as the changes in desorption of pyridine from the acid sites and indirectly as the suppression of cracking reactions during the ring opening of decalin on the Pt-modified catalysts. The observed results are discussed in terms of the interatomic potential model. 相似文献
170.
Narendra Singh 《Optik》2010,121(10):918-925
We propose a new method for image encryption using improper Hartley transform and chaos theory. Improper Hartley transform is a Hartley transform in which the phase between the two Fourier transforms is a fractional multiple of π/2. This fractional order is called fractional parameter and serves as a key in the image encryption and decryption process. Four types of chaos functions have been used. These functions are the logistic map, the tent map, the Kaplan-Yorke map and the Ikeda map. Random intensity masks have been generated using these chaotic functions and are called chaotic random intensity masks. The image is encrypted by using improper Hartley transform and two chaotic random intensity masks. The mean square error has been calculated. The robustness of the proposed technique in terms of blind decryption has been tested. The computer simulations are presented to verify the validity of the proposed technique. 相似文献