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91.
The solvent relaxation and rotational dynamics of coumarin 153 have been investigated in a new room temperature ionic liquid, 1-(2-methoxyethyl)-1-methylpyrrolidiniumtris(pentafluorethyl)trifluorophosphate [[MOEMPL][FAP]], at three different excitation wavelengths with a variation in temperature. Wavelength -dependent fluorescence decay behavior of the probe molecule in the present medium has been investigated by studying the time dependent fluorescence Stokes shift in the ps–ns time scale. The dynamic fluorescence Stokes shift measurements suggest that the time-resolvable part of the solvation dynamics is biphasic in nature and the average solvation time depends on the excitation wavelengths. Rotational coupling constants, obtained from the time- resolved anisotropy data, indicate no specific interaction between the probe molecule and the ionic liquids. The excitation wavelength dependent solvation dynamics is attributed to the heterogeneous nature of the present ionic liquid. 相似文献
92.
Experimental data on masses and lifetimes of unstable particles falls into a pattern, a brief review of some interesting consequences
is presented here. From the experience in semiclassical methods and recent advances in quantum chromodynamics, it is proposed
that an appropriate generalization of the Gutzwiller trace formula for field theories may lead to a systematic semiclassical
chromodynamics theory. The theory can be developed to get appropriate dynamics leading to an explanation of pattern discovered
in the empirical data. 相似文献
93.
We employ the spectral properties of cyclic random matrices to understand the approach to equilibrium of a biased random walk on a disordered lattice. The simplicity of the calculations and the flexibility with which randomness can be modelled makes it a worthwhile alternative. 相似文献
94.
Hardev SinghMukhtiyar Singh Sarvesh KumarManish K. Kashyap 《Physica B: Condensed Matter》2011,406(20):3825-3830
The electronic properties of RO2 (R=Si, Ge, Sn and Pb; a group IVA element) compounds in rutile structure have been calculated using WIEN2k implementation of full potential linearized augmented plane wave (FPLAPW) method. The exchange and correlation (XC) effects are taken into account by an orbital independent modified Becke Johnson (MBJ) potential as coupled with Local Density Approximation (LDA) for all the compounds except for PbO2 where only Generalized Gradient Approximation (GGA) is considered for the same. We predict a direct band gap in all these compounds with continuous decrease as the atomic size of IVA element increases such that there is an appearance of semimetallic band structure for the last compound, PbO2. The largest band gap (7.66 eV) has been found for SiO2, which governs its insulating nature. We observe that MBJLDA results for band gaps of these compounds are far better than those obtained using GGA and Engel-Vosko's GGA (EV-GGA). A very good agreement is observed between MBJLDA band gaps with corresponding experimental values as compared to other calculations. The electronic band structures are also analyzed in terms of contributions from various electrons. 相似文献
95.
Sudhir Malik S. K. Soni R. K. Shivpuri 《Zeitschrift fur Physik C Particles and Fields》1995,67(2):239-244
Experimental results on multiplicity distributions for full phase space and in different pesudorapidity windows of charged secondary particles produced in proton-nucleon collisions at 800 GeV are presented and discussed. It is found that all these multiplicity distributions are well described by negative binomial distributions. We interpret our results on the basis of clan model. The bin size dependence of multiplicity distribution of charged secondary particles in proton-nucleon interactions is analysed in terms of multifractals. The values of generalised dimensions obtained from fitted distributions show a good agreement with those obtained from the data. 相似文献
96.
97.
98.
Efficient solid phase synthesis of oligoribonucleotide and its phosphorothioate analogue is described that utilizes the dimethoxytrityl (DMTr) for 5′-protection and t-butyldimethylsilyl (t-BDMS) group for 2′-protection of ribonucleoside monomers and the H-phosphonate coupling procedure. The synthetic cycles have been optimised to use only 8–10 fold excess of monomer at each coupling step, leading to an average coupling yield of 97%. 相似文献
99.
INDEPENDENT EFFECTS OF PHYTOCHROME AND NITRATE ON NITRATE REDUCTASE AND NITRITE REDUCTASE ACTIVITIES IN MAIZE 总被引:1,自引:0,他引:1
Abstract— Involvement of phytochrome in the regulation of nitrate reductase (NR) and nitrite reductase (NIR) activities in excised, etiolated leaves of Zea mays (L.) variety 'Ganga-5' is demonstrated using low energy and high irradiance responses of phytochrome action. Photoreversibility by far-red light of red light stimulated increases in NR and NIR activities was lost by 2 h. Red light given to the leaves, when induction by NO- 3 , was saturated, further increased both enzyme activities. Even if red light was given 4–8 h before NO- 3 , it still increased both NR and NIR activities. 相似文献
100.
Paul S 《Applied biochemistry and biotechnology》1998,75(1):13-24
The light (L) chain of a model antibody (Ab) was deduced to contain a serine protease-like catalytic site capable of cleaving
peptide bonds. The catalytic site is encoded by a germline VL gene. The catalytic activity can potentially be improved by somatic sequence diversification and pairing of the L chain with
the appropriate heavy chain. Autoimmune disease is associated with increased synthesis of antigen (Ag)-specific Abs, but the
reasons for this phenomenon are not known. Only recently has attention turned to the functional role of the catalytic function.
Preliminary studies confirm that the catalytic cleavage of peptide bonds is a more potent means to achieve Ag neutralization,
compared to reversible Ag binding. Administration of a monoclonal Ab to VIP in experimental animals induces an inflammatory
response in the airways, suggesting that catalytic autoantibodies to this peptide found in airway disease and lupus are capable
of causing airway dysfunction. The phenomenon of autoantibody catalysis can potentially be applied to isolate efficient catalysts
directed against tumor or microbial Ags by exposing the autoimmune repertoire to such Ags or their analogs capable of recruiting
the germline VL gene encoding the catalytic site. 相似文献