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881.
882.
We show how the theory of large deviations in the coin toss experiment can give some insight into nonequilibrium fluctuation
theorems and intermittency in turbulence.
相似文献
883.
Majid M. Heravi Ali J. Sabaghiani Mehdi Bakavoli Mitra Ghassemzadeh Khadijeh Bakhtiari 《中国化学会会志》2007,54(1):123-126
2,4‐Dinitrophenylhydrazones were converted to their parent carbonyl compounds using hexamethylenetetramine‐bromine complex supported onto wet alumina under classical heating and microwave irradiation. 相似文献
884.
A. K. Mitra V. B. Gawandi K. George H. Mohan T. Mukherjee 《Research on Chemical Intermediates》2009,35(1):13-20
5,8-dihydroxy-1,4-dihydro-1,4-methanonaphthalene (DDMN), a substituted phenol, is synthesized by the reduction of a cyclic
dione, 1,4,4a,8a-tetrahydro-endo-1,4-methano-naphtha-5,8-dione (THMND). The pulse radiolysis technique has been employed to
understand the nature of transient species formed by the reaction of radiolytic species of water radiolysis with DDMN. •OH radicals were observed to react with DDMN with a bimolecular rate constant of 1.5 × 1010 dm3 mol−1 s−1. The inhibition of radiation-induced lipid-peroxidation by DDMN was studied in rat liver microsomes by assessing the formation
of thiobarbituric acid reactive substances (TBARS). It was found to be strongly inhibitory. The results suggest that DDMN
has very good antioxidant activity and may possibly emerge as a good radio-protector.
Dr. Hari Mohan: since deceased. 相似文献
885.
The infrared behaviour of the gauge-invariant dressed fermion propagator in massless QED3 is discussed for three choices of dressing. It is found that only the propagator with the isotropic (in three Euclidean dimensions) choice of dressing is acceptable as the physical fermion propagator. It is explained that the negative anomalous dimension of this physical fermion does not contradict any field-theoretical requirement. 相似文献
886.
Photophysical properties of prototype excited state intramolecular proton transfer (ESIPT) system 4-methyl-2,6-diformyl phenol (MFOH) and its derivatives were studied by steady state and time-resolved fluorescence spectroscopy as well as by ab-initio quantum chemical calculation. It has been found that nonradiative decay process is the most important deactivation channel in all the cases and the hydrogen bonded enol conformer is stable in the ground state whereas, the proton transferred keto form is energetically favoured in the S1(ππ*) state. However, the net gain in stabilization in the process of ESIPT is almost unaffected by the substitution. The reversal of stability in the excited state was explained on the basis of the nature of frontier molecular orbital in all the cases. Intrinsic reaction coordinate analysis showed that drastic change in nonbonded interoxygen distance R(O-O) in the proton transfer pathway causes the switch over from the enol to keto configuration. A close comparison of several properties like molecular geometry, hydrogen bond strength and atomic charge in different derivatives of MFOH were found to be consistent and in good agreement with the experimental results obtained from time-resolved fluorescence experiments. 相似文献
887.
R. Maity S. Das M.K. Mitra K.K. Chattopadhyay 《Physica E: Low-dimensional Systems and Nanostructures》2005,25(4):605-612
Zinc oxide (ZnO) nano/microfibrous thin films were successfully synthesized by a catalyst free solution route on glass and Si substrates. X-ray diffraction study revealed the formation of ZnO nanofibers of hexagonal crystalline structure. The texture coefficient of different planes varied with annealing temperature and that of the (0 0 2) plane was the highest for films annealed at temperature 873 K. Scanning electron micrograph showed the well formation of ZnO nano/microfibers with an average diameter 500 nm and having an average aspect ratio 150. UV–Vis–NIR spectroscopic study for the films deposited on glass substrates showed the high transmittance in the visible and near-infrared region. It was also observed that the band gap energy decreased as the films were annealed at higher temperature. The band gap energies of nanostructured ZnO thin films were determined to be in the range 3.03–3.61 eV. The photoluminescence study showed an UV emission peak at 397 nm, a visible blue–green emission peak at 468 nm and a green emission peak at 495 nm. Field emission properties of nanofiber ZnO thin film showed considerably low turn-on field around 1.4 V/μm. The emission current was as high as 70 μA at the field of 3.6 V/μm. 相似文献
888.
The dimeric copper(II) complex di‐µ‐chloro‐bis[chloro(di‐3,5‐dimethylpyrazole)copper(II)] (A) in the presence of co‐oxidant hydrogen peroxide acts as a catalyst for the oxidation of benzylic alcohols to give the corresponding aldehydes. In the presence of hydrogen peroxide it also catalyses the oxidation reaction of 2,6‐dimethylphenol to 4,4′‐dihydroxy‐3,5,3′,5′‐tetramethylbiphenyl. The oxidative reactions by bis‐pyridinium tetrachlorocopper(II) (B) in the presence of hydrogen peroxide were compared for similar catalytic reactions of A, and it is observed that B can catalyse the oxidation of aromatic diols, 2,6‐dimethylphenol and thiophenol, but is not suitable for oxidation of benzylic alcohols. Bis‐(N‐phenyl‐3,5‐dimethylpyrazole)copper(II) nitrate monohydrate (C) has a suitable redox potential for one‐electron oxidation. It can oxidize ferrocene to the ferricinium cation, and it can liberate bromine from tetra‐alkylammonium bromides. The complex is catalytically effective for the oxidation of different aromatic and aliphatic aldehydes to the corresponding carboxylic acids. The compound is also effective in transforming benzylic amine to benzylalcohol and benzaldehyde. It can also oxidize diphenylmethane to give benzophenone and diphenylmethanol. It is observed that in each of these complexes a quasi‐reversible Cu(I)–Cu(II) species is present and facilitates the single‐electron oxidation process. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
889.
A.N. Mitra 《Physics letters. [Part B]》1982,116(4):243-246
A three-way preon interaction with a spin-dependence of the form σμν(1) σνγ(2) σλμ(3), is proposed for a two-flavor (t,v) preon model, within a Bethe-Salpeter framework. This mechanism not only eliminates all states but severely restricts the spatial symmetries of allowed states to at most threedistinct “generations” with very strong selection rules forbidding transitions among them. 相似文献
890.