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91.
JPC – Journal of Planar Chromatography – Modern TLC - 相似文献
92.
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
93.
We employ the Airy stress function to derive analytical solutions for plane strain static deformations of a functionally graded
(FG) hollow circular cylinder with Young’s modulus E and Poisson’s ratio v taken to be functions of the radius r. For E
1 and v
1 power law functions of r, and for E
1 an exponential but v
1 an affine function of r, we derive explicit expressions for stresses and displacements. Here E
1 and v
1 are effective Young’s modulus and Poisson’s ratio appearing in the stress-strain relations. It is found that when exponents
of the power law variations of E
1 and v
1 are equal then stresses in the cylinder are independent of v
1; however, displacements depend upon v
1. We have investigated deformations of a FG hollow cylinder with the outer surface loaded by pressure that varies with the
angular position of a point, of a thin cylinder with pressure on the inner surface varying with the angular position, and
of a cut circular cylinder with equal and opposite tangential tractions applied at the cut surfaces. When v
1 varies logarithmically through-the-thickness of a hollow cylinder, then the maximum radial stress, the maximum hoop stress
and the maximum radial displacements are noticeably affected by values of v
1. Conversely, we find how E
1 and v
1 ought to vary with r in order to achieve desired distributions of a linear combination of the radial and the hoop stresses. It is found that for
the hoop stress to be constant in the cylinder, E
1 and v
1 must be affine functions of r. For the in-plane shear stress to be uniform through the cylinder thickness, E
1 and v
1 must be functions of r
2. Exact solutions and optimal design parameters presented herein should serve as benchmarks for comparing approximate solutions
derived through numerical algorithms. 相似文献
94.
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
95.
We find closed-form solutions for axisymmetric plane strain deformations of a functionally graded circular cylinder comprised of an isotropic and incompressible second-order elastic material with moduli varying only in the radial direction. Cylinder's inner and outer surfaces are loaded by hydrostatic pressures. These solutions are specialized to cases where only one of the two surfaces is loaded. It is found that for a linear through-the-thickness variation of the elastic moduli, the hoop stress for the first-order solution (or in a cylinder comprised of a linear elastic material) is a constant but that for the second-order solution varies through the thickness. The radial displacement, the radial stress and the hoop stress do not depend upon the second-order elastic constant but the hydrostatic pressure and hence the axial stress depends upon it. When the two elastic moduli vary as the radius raised to the power two or four, the radial and the hoop stresses in an infinite space with a pressurized cylindrical cavity equal the pressure in the cavity. For an affine variation of the elastic moduli, the hoop stress in an internally loaded cylinder made of a linear elastic isotropic and incompressible material at the point is the same as that in a homogeneous cylinder. Here Rin and Rou equal, respectively, the inner and the outer radius of the undeformed cylinder and R the radial coordinate of a point in the unstressed reference configuration. 相似文献
96.
97.
98.
A material instability criterion for locally adiabatic plane strain deformations of a thermoviscoplastic material near a notch-tip is proposed. It is used to rank eight materials according to their susceptibility to instability. 相似文献
99.
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
100.
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