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11.
Decomposition of isopropanol (IPA) on V2O5, Li0.02V2O5, Na0.02V2O5, Na0.06V2O5, Li0.33V2O5, and Na0.33V2O5 has been studied in the temperature range 186–300°C. The first four catalysts (α-phase) show predominately dehydration, whereas the last two (β-phase) have comparable dehydration and dehydrogenation activity. Dehydration activity increases with alkali metal concentration within the α-phase, but falls sharply on the β-phase catalysts. This difference is attributed to the different rate determining steps for the reaction on the α- and β-phase catalysts. X-ray and ir spectral data show that the β-phase catalysts are much more stable than the α-phase. A mechanism for the dehydration of IPA based on the electrical resistivity, ESR spectra, and kinetic data has been proposed. 相似文献
12.
The Born→Green→Yvon equation for molecular fluid has been deduced considering the orientational distribution functions. The
isotropic and anisotropic parts of the distribution function have been separated. The expressions deduced can be used in the
case of mixtures and for the non-central type of intermolecular potential energy. 相似文献
13.
M. F. Bertino R. R. Gadipalli L. A. Martin J. G. Story B. Heckman S. Guha N. Leventis 《Journal of Sol-Gel Science and Technology》2006,39(3):299-306
Silica hydrogels and planar substrates were patterned with CdS nanoparticles using a photolithographic method based on the
photo dissociation of thiols and cadmium-thiolate complexes. Silica hydrogels were prepared via a standard base-catalyzed
route. The solvent was exchanged with an aqueous solution of CdSO4 and 2-mercaptoethanol, and the samples were then exposed to a focused ultraviolet beam. Planar substrates were patterned
by illuminating a precursor solution spin coated on the substrates. CdS nanoparticles formed in the illuminated spots, and
had a diameter below about 2 nm. The diameter of the spots illuminated by the UV beam could be varied from a few hundred to
a few μm, on both hydrogels and planar substrates. Samples were characterized with transmission electron microscopy, X-ray
photoelectron spectroscopy, X-ray diffraction, and optical absorption, photoluminescence and Raman spectroscopies. All these
techniques confirmed the chemical identity of the CdS nanoparticles. To investigate the mechanism of nanoparticle formation,
we took absorption spectra of the precursor solution as a function of irradiation time. In unirradiated solutions, we noticed
a maximum at 250 nm, characteristic of Cd-thiolate complexes. The absorption at 250 nm decreased with increasing irradiation
time. A new band appeared at 265 nm for exposures around 5 min, and that band shifted to 290 nm in samples exposed for 10 min.
A yellow precipitate formed after about 30 min. XRD showed that the precipitate was cubic CdS, with a mean particle size of
1.4 nm. We attribute formation of CdS to the photodissociation of the thiols and of the Cd-thiolates. UV irradiation of these
precursors yields a series of species that can react with Cd2+, such as RS·, S2− and H2S. Small CdS nanoparticles form in the initial stages of illumination, and present absorption bands in the 265–290 nm region.
These CdS aggregates grow, coalesce and precipitate for longer irradiation times. 相似文献
14.
Summary The kinetics of formation of square-planar CuII and NiII complexes of the quadridentate ligand, ethylenebisbiguanide, have been studied spectrophotometrically in aqueous HOAc–NaOAc buffer, at ionic strength 0.2 mol dm–3, in the 25–35°C temperature range. The observed rate constants for the formation reactions are independent of pH (and of OAc– concentration) in the pH range used (3.6–4.8 for CuII and 5.0–5.8 for NiII) where the product complexes form stoichiometrically, but show first-order dependence on the ligand concentration;i.e. kobs=kf[L]total. At 25°C kf values (dm3 mol–1s–1) are 35.2±0.4 for CuII and (8.4±0.1)×10–3 for NiII. The mechanism of the reactions is discussed. 相似文献
15.
The one-electron oxidation of toluidine blue by specific oxidising radicals such as Cl
2
−
, Tl(II), N3, Br
2
−
etc. has been studied by employing the pulse radiolysis technique. The Br
2
−
radical was found to be less efficient in oxidising toluidine blue as compared to Cl
2
−
., Tl+2 and N3. The semioxidised species exhibited only onepK
a indicating the presence of two conjugate acid-base forms whose spectral and kinetic features were evaluated. Reaction of
OH radicals with the dye gave rise to a transient species which exhibited spectral and kinetic features different from that
of the semioxidised species indicating that the mode of reaction of OH is different. 相似文献
16.
ESCA and ESR studies on TMI incorporating alumina-boria catalyst systems for CO conversion show the presence of carbidic phase and no valence change of the incorporated copper in the spent catalyst. 相似文献
17.
Oğul Esen Anindya Ghose Choudhury Partha Guha Hasan Gümral 《Regular and Chaotic Dynamics》2016,21(2):175-188
Degenerate tri-Hamiltonian structures of the Shivamoggi and generalized Raychaudhuri equations are exhibited. For certain specific values of the parameters, it is shown that hyperchaotic Lü and Qi systems are superintegrable and admit tri-Hamiltonian structures. 相似文献
18.
We introduce the Schlesinger transformations for the Gambier, linearisable, equation and by combining the former construct the contiguity relations of the solutions of the latter. We extend the approach to the discrete domain obtaining thus the Schlesinger transformations and the contiguity relations of the solutions of the Gambier mapping. In all cases the resulting contiguity relation is a linearisable equation, involving free functions, and which can be related to the generic Gambier mapping. 相似文献
19.
V. Sankara Sastry S. Kalavathy B. K. Guha R. Baskaran U. De J. Janaki 《Phase Transitions》2013,86(1-2):97-105
Electrical resistance measurements at low temperatures and high quasihydrostatic pressures on superconducting and non-superconducting varieties of Y0.8Ba1.2Cu2O5 (obtained by annealing in oxygen and air respectively) show striking anomalies in the vicinity of 100K and 40K. Arguments are presented to show that these anomalies as also the occurrence of T 's in the oxide superconductors either in the vicinity of 100K or of 40K are connected with their layered structure containing planes of Cu-O otahedral complexes. 相似文献
20.