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151.
邻-甲氧基苯酚和α-,β-环糊精包合现象的理论与实验研究 总被引:1,自引:0,他引:1
通过紫外可见光谱法考察了水溶液中邻-甲氧基苯酚(o-Mop)和α-与β-环糊精(CD)的分子间相互作用, 利用Hildebrand-Benesi方程给出了两个包合物的稳定常数(Ks). 采用半经验PM3方法研究了α-,β-CD和o-Mop及其类似物苯酚(Phe)、丁香酚(Eug)之间的包络作用, 阐述了这些主客体包合作用过程中体系能量随主客体相对位置改变而变化的细节, 据此推断出主-客体包合物可能的分子结构, 计算了包合物的稳定化能(ΔEs). 研究结果表明, 本文所选主客体体系而言, 当客体和同一种主体分子作用时, 超分子包合物的ΔEs随着客体分子苯环上取代基团数目的增多而增加. 基于PM3方法优化得到的主-客体包合物在真空中的分子结构和通过实验方法在水溶液中测定的结构一致. 相似文献
152.
Summary Molecular surface areas accessible to a 4 ? diameter spherical probe were calculated from crystallographic data for five proteins:
α-chymotrypsinogen A, lysozyme, trypsinogen, ribonuclease A and ribonuclease S. The retention factors of various proteins
were measured on stationary phases having polyether- and phenylligates and with aqueous eluents containing (NH4)2SO4, Na2SO4 or NaCl at pH 7.0. The logarithmic retention factors were plotted against the salt molality and the hydrophobic interaction
parameters evaluated from the limiting slopes of the plots at high salt concentrations for the proteins in the chromatographic
systems investigated. The hydrophobic interaction parameters thus obtained were linear in both the molecular surface areas
of the proteins and the molal surface tension increments of the salts. The experimental results obtained with these relatively
simple proteins of known molecular structure, which were available in high purity, support earlier theoretical predictions
for the dependence of the hydrophobic interaction parameter on the surface area of the protein and the surface tension raising
effect of the salt. 相似文献
153.
Alessandro D'Aprano Camillo La Mesa Noemi Proietti Bianca Sesta Sonia Tatone 《Journal of solution chemistry》1994,23(12):1331-1346
The interactions between octyl--D-glucoside and glycine in water have been investigated by surface tension, viscosity, and density measurements. The results show that the -amino acid causes an unexpected lowering of the critical micellar concentration of octyl--D-glucoside. Such a finding has been interpreted in temss of dipole-dipole interactions between the hydrophilic site of the surfactant and the peptidic cosluttes. From three to seven amino acid molecules have been estimated to be coordinated with each glucoside unity in the micellar state. The research has been extended to glycine oligopeptides and L-lysine. The latter compound has effects similar to those observed with glycine whereas diglycine and triglycine show weaker effects on the micellization process. 相似文献
154.
Mathew D. Penrose 《Journal of statistical physics》1994,77(1-2):3-15
LetG
R
be the graph obtained by joining all sites ofZ
d which are separated by a distance of at mostR. Let (G
R
) denote the connective constant for counting the self-avoiding walks in this graph. Let (G
R
) denote the coprresponding constant for counting the trees embedded inG
R
. Then asR, (G
R
) is asymptotic to the coordination numberk
R ofG
R
, while (G
R
) is asymptotic toek
R. However, ifd is 1 or 2, then (G
R
)-k
R
diverges to –.Dedicated to Oliver Penrose on this occasion of his 65th birthday. 相似文献
155.
Since more than a decade, abi-scale, unified approach to strong and gravitational interactions has been proposed, that uses the geometrical methods of general relativity, and yielded results similar to strong gravity theory's. We fix our attention, in this note, on hadron structure, and show that also the strong interaction strength S, ordinarily called the (perturbative) coupling-constant square, can be evaluated within our theory, and found to decrease (increase) as the distancer decreases (increases). This yields both the confinement of the hadron constituents (for large values ofr) and their asymptotic freedom (for small values ofr inside the hadron): in qualitative agreement with the experimental evidence. In other words, our approach leads us, on a purely theoretical ground, to a dependence of S onr which had been previously found only on phenomenological and heuristic grounds. We expect the above agreement to be also quantitative, on the basis of a few checks performed in this paper, and of further work of ours on calculating meson mass spectra. 相似文献
156.
We consider variational problems involving nonlocal free energy functionals that arise from Gibbs measures with Kac potentials and are related to the characterization of the optimal (i.e., typical) shape of an interface under given constraints on the magnetization profile. 相似文献
157.
Feng-Yu Wang 《Journal of statistical physics》1996,84(1-2):277-293
LetM be a compact, connected Riemannian manifold (with or without boundary); we study the logarithmic Sobolev constant for stochastic Ising models on
. Let {} be a sequence of cubes inZ
d
; we show that the logarithmic Sobolev constant for the finite systems onM
A
shrinks at most exponentially fast in ||(d-1)/d
(d2), which is sharp in order for the classical Ising models withM=[–1, 1]. Moreover, a geometrical lemma proved by L. E. Thomas is also improved. 相似文献
158.
G. Alberti G. Bellettini M. Cassandro E. Presutti 《Journal of statistical physics》1996,82(3-4):743-796
We consider an Ising spin system with Kac potentials in a torus of d,d>-2, and fix the temperature below its Lebowitz-Penrose critical value. We prove that when the Kac scaling parameter vanishes, the log of the probability of an interface becomes proportional to its area and the surface tension, related to the proportionality constant, converges to the van der Waals surface tension. The results are based on the analysis of the rate functionals for Gibbsian large deviations and on the proof that they -converge to the perimeter functional of geometric measure theory (which extends the notion of area). Our considerations include nonsmooth interfaces, proving that the Gibbsian probability of an interface depends only on its area and not on its regularity. 相似文献
159.
F. Cesi G. Guadagni F. Martinelli R. H. Schonmann 《Journal of statistical physics》1996,85(1-2):55-102
We consider the two-dimensional stochastic Ising model in finite square with free boundary conditions, at inverse temperature >0 and zero external field. Using duality and recent results of Ioffe on the Wulff construction close to the critical temperature, we extend some of the results obtained by Martinelli in the low-temperature regime to any temperature below the critical one. In particular we show that the gap in the spectrum of the generator of the dynamics goes to zero in the thermodynamic limit as an exponential of the side length of , with a rate constant determined by the surface tension along one of the coordinate axes. We also extend to the same range of temperatures the result due to Shlosman on the equilibrium large deviations of the magnetization with free boundary conditions. 相似文献
160.
Classical verigin problem as a limit case of verigin problem with surface tension at free boundary 总被引:1,自引:0,他引:1
TAOYOUSHAN YIFAHUAI 《高校应用数学学报(英文版)》1996,11(3):307-322
In this psper we consider Verigin problem with surface tension st free 相似文献