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141.
Santosh Kumar Samantaray Kulamani Parida 《Reaction Kinetics and Catalysis Letters》2003,78(2):381-387
The effect of addition of titania to silica was examined by various characterization techniques such as FT-IR, BET surface
area, surface acid strength/acid sites by the Hammett indicator method and Br?nsted/Lewis acid sites by pyridine adsorbed
IR study. Ti-O-Si bond is formed in case of TiO2-SiO2 sample, as observed from FT-IR data. Acid strength, surface acid sites, and rate constant for esterification of acetic acid
are increased with Ti-O-Si bonding and sulfate impregnation. Both Br?nsted and Lewis acid sites are responsible for catalysing
the esterification reaction.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
142.
The physico-chemical properties as well as catalytic activity of some γ-irradiated manganese nodules has been studied using
H2O2 decomposition and CO oxidation and were compared with the unirradiated samples. The catalytic activities of irradiated nodules
were correlated with various physico-chemical properties. 相似文献
143.
Dipti Prakasini Das Kulamani Parida Bhudev Ranjan De 《Journal of molecular catalysis. A, Chemical》2005,240(1-2):1-6
The photodegradation of phenol was studied in the aqueous solutions over titania pillared zirconium phosphate and titanium phosphate under solar radiation and compared with that of the UV-radiation (6 W low pressure Hg vapor lamp). This reaction was studied by varying different parameters such as catalyst dose, initial phenol concentration, pH of solution and irradiation time. The degradation rate of phenol was favourable under neutral pH condition. The degradation process approximately obeyed first-order kinetics with apparent rate of degradation constant increasing with decreasing the initial phenol concentration. 相似文献
144.
Sanghamitra Parida Ravindra Datta Jonathan S. Dordick 《Applied biochemistry and biotechnology》1992,33(1):1-14
The use of partially hydrated porous silica particles has been studied as a support for cofactor-dependent enzymatic catalysis
in organic solvents. At an optimal pore hydration corresponding to 70% pore volume, horse liver alcohol dehydrogenase catalyzes
the oxidation and reduction of alcohols and aldehydes, respectively, with rates sixfold higher than with nonporous glass beads
as the enzymatic support and with cofactor recycling numbers in excess of 105. Thus, supported aqueous-phase enzymatic catalysis makes highly effective use of the enzyme and cofactor by coimmobilization
and by providing a high interfacial area for reactions in organic media. 相似文献
145.
M. K. Parida 《Pramana》1995,45(1):209-228
We discuss recent contributions on threshold effects in grand unfiied theories including minimal SUSY SU (5), non-SUSY modifications of the grand desert in SU(5) and SO(10), and SO(10) with single intermediate symmetires. Consequences of theorems on vanishing GUT-scale corrections to sin2 θw in SO(10) with SU(2) L XSU(2) R XSU(4) c (g2l =g2R ) intermediate symmetry are discussed and vanishing corrections on the inter-mediate scale are explicitly demonstrated where predictions are more precise. Threshold and higher dimensional operator effects in SUSY SU(5) recently derived by a number of authors are presented. 相似文献
146.
147.
M K Parida 《Pramana》1993,41(1):271-282
We review general results on threshold effects and their implications on GUTs in the context of LEP data. Among the blooming grand-desert models, threshold effects are computed in the presence of a single real scalar ζ (3, 0, 8) with Mζ?1010 GeV leading to experimentally testable predictions on the proton lifetimeτ p in SU (5) and, in addition, small neutrino masses in SO (10) needed for the solar neutrino flux and the dark matter of the universe. The fine structure constant matching at MZ is ensured by including threshold effects on the unification coupling. In the minimal SUSY SU (5) such effects at the GUT scale modify the prediction of the supersymmetric mass threshold near the TeV scale and the precision measurments of the Standard Model couplings at MZ probe into the superheavy mass spectrum. Consequences of theorems proved very useful for threshold, compactification and multiloop effects are discussed. It is noted that in a class of GUTs the highest intermediate scale MI above which G224P becomes a good symmetry is not affected by the GUT threshold or compactification effects or multiloop contributions in the range MI-MU. But spontaneous compatification effects can decrease the intermediate scale drastically in models where parity and SU(2)R breakings are decoupled. Low mass WR-bsosns are permitted in models with decoupled parity and SU (2)R breakings. 相似文献
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