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101.
Peak dispersion effects in nonaqueous capillary electrophoretic separations of aromatic anionic analytes were investigated in a propanolic background electrolyte solution. Poly(glycidylmethacrylate-co-N-vinylpyrrolidone) coating was applied to the capillary to suppress the electroosmotic flow and to improve the repeatability of the migration times. Electrical field strengths up to 2000 Vcm(-1) were applied in separations and the separation efficiencies were compared with theoretical values calculated on the basis of plate height theory. The contributions to the total plate height were calculated for injection plug length, diffusion, Joule heating, electromigration dispersion, analyte adsorption to the capillary wall, and detector slit aperture length. Analyte diffusion coefficients were measured by Taylor dispersion method, while distribution constants were measured chromatographically. Agreement between the calculated and empirical results was fairly good even though some approximations were required. In most cases the longitudinal diffusion contribution governed the total plate height, while the contribution of Joule heating was insignificant even at exceptionally high field strengths used. The relatively long detection slit aperture was found to influence the separation efficiency strongly, while the other dispersion sources that were investigated were of minor importance, except for adsorption in the case of one analyte. With all analytes, the dispersive effect of longitudinal diffusion was reduced as the field strength was increased, leading to enhanced migration velocities and faster separations. 相似文献
102.
Let f be a smooth nondegenerate real valued function on a finite dimensional, compact and connected Riemannian manifold. The bipartite min-max graph is defined as follows. Its nodes are formed by the set of local minima and the set of local maxima. Two nodes (a local minimum and a local maximum) are connected in by means of an edge if some trajectory of the corresponding gradient flow connects them. Given a natural number k, we construct a function f such that the length of the shortest path in between two specific local minima exceeds k. The latter construction is independent of the underlying Riemannian metric. 相似文献
103.
A direct kinetic study is reported for the electrophilic amination of substituted phenylmagnesium bromides with N,N‐dimethyl O‐(mesitylenesulfonyl)hydroxylamine in THF. Rate data, Hammett relationship, and activation entropy are consistent with a SN2 displacement involving the attack of carbanions to sp3N in the amination reagent (AR). Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
104.
Perttu Permi Sami Heikkinen Ilkka Kilpelinen Arto Annila 《Journal of magnetic resonance (San Diego, Calif. : 1997)》1999,139(2):273
1H-detected two-dimensional double-/zero-quantum experiments are described for measurement of homonuclear 2JHH-couplings of NH2 or CH2 groups in proteins. These experiments utilize multiple-quantum coherence for determination of the size and the absolute sign of the geminal scalar and dipolar couplings in the presence of broad lines. Spectra are simplified by gradient selection and spin-state selective filters. 相似文献
105.
106.
A bidentate ligand derived from cinnamaldehyde and acetylacetone and its copper(II) complex have been synthesized and characterized
by elemental analysis, UV-Vis, IR, ESR and magnetic susceptibility measurements. Magnetic susceptibility measurements, ESR
and electronic spectral data indicate the presence of six coordinated Cu(II) ion. The ligand and complex are tested for antibacterial
activity againstPseudomonas aeroginosa. They are found to show the antibacterial activity. 相似文献
107.
O. Üzengi Aktürk E. Aktürk M. Tomak 《International Journal of Theoretical Physics》2008,47(12):3310-3320
In this paper, we focus on Sobolev inequality in the context of Sharma-Mittal entropy. Using this new inequality, generalized entropic uncertainty relation in accordance with Sharma-Mittal entropy is derived and the pseudoadditivity relation has been obtained. This new entropic uncertainty relation has then been applied to physical examples such as one dimensional harmonic oscillator and Pösch-Teller potential. Finally, it has been shown that for certain values of the parameters of Sharma-Mittal measure, the present results reduce to the corresponding results of Shannon, Renyi and Tsallis measures. 相似文献
108.
Assuming that a dynamical system (DS) has a periodic solutionwith period T in the neighborhood of an equilibrium, a newDS can be obtained which governs approximately the motion oftrajectories in the neighborhood of the periodic orbit. Approximatesymmetries and first integrals have been discussed for this DS. Theresults have been demonstrated on the Helmholtz oscillator. 相似文献
109.
110.
Let (u
n
) be a sequence of real numbers. In this paper we introduce some Tauberian conditions in terms of regularly generated sequences
for (A, k) summability method. 相似文献