Branched polymers in a wedge geometry in three dimensions

We investigate the statistical and dimensional properties of uniform star polymers attached by the branching vertex of degreef in a wedge geometry in three dimensions and described by the wedge angles and. We show that the growth constant is equal to ^f , where is the self-avoiding walk limit. Thef and (, ) dependences of the corresponding critical exponent _f (, ) are studied using Monte Carlo techniques. In the casef=1, our results are compared with existing predictions obtained from series expansion and renormalization group methods. We have also estimated the amplitudes for the mean square radius of gyration and the mean square end-to-end branch length. Our results for the ratio of the mean square radius of gyration of anf-star to that of a linear polymer of the same degree of polymerization attached in a similar wedge, and the analogous ratio for the mean square end-to-end branch length, are consistent with these ratios being lattice-independent quantities.     

Determination of the optimal initial function and the parameters for nonlinear time-delay systems

This paper deals with dynamic systems described by nonlinear differential-difference equations of retarded type. The problem considered is to determine the initial function and certain system parameters which minimize a given cost functional. A computational method is presented and some convergence results are given. Numerical examples of linear and nonlinear systems are also included.     

From dilute to dense self-avoiding walks on hypercubic lattices

A field-theoretic representation is presented to count the number of configurations of a single self-avoiding walk on a hypercubic lattice ind dimensions with periodic boundary conditions. We evaluate the connectivity constant as a function of the fractionf of sites occupied by the polymer chain. The meanfield approximation is exact in the limit of infinite dimensions, and corrections to it in powers ofd ^–1 can be systematically evaluated. The connectivity constant and the site entropy calculated throughout second order compare well with known results in two and three dimensions. We also find that the entropy per site develops a maximum atf1–(2d)^–1. Ford=2 (d=3), this maximum occurs atf~0.80 (f~0.86) and its value is about 50% (30%) higher than the entropy per site of a Hamiltonian walk (f=1).     

Potentiometric studies on the complexation equilibria between some trivalent lanthanide metal ions and biologically active 2-hydroxy-1-naphthaldehyde thiosemicarbazone (HNATS)

Summary The chelation behaviour of some trivalent lanthanide and yttrium metal ion with biologically active 2-hydroxy-1-naphthaldehyde thiosemicarbazone (HNATS) has been investigated by potentiomotric measurements at 20±0.5°C in 75% (v/v) dioxane-water medium at various ionic strengths of sodium perchlorate. The method of Bjerrum and Calvin, as modified by Irving and Rossotti has been used to find out the values of (average number of ligand bound per metal ion) andpL (free ligand exponent). The formation constants of metal chelates have been computed on a PC-XT computer, using a program patterned after that of Sullivan et al. to give _n values using weighted least squares method. TheS _min values (S _min =²) have been calculated. The order of formation constants of chelates was found to be: La³⁺3+3+3+3+3+3+3+3+3+. The formation constants of the chelates formed have been correlated to size and ionization potentials of the metal ions.

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Potentiometrische Untersuchungen der Komplexierungsgleichgewichte zwischen einigen trivalenten Metallionen und biologisch aktivem 2-Hydroxy-1-naphthaldehyd-thiosemicarbazon (HNATS)

Zusammenfassung Es wurde das Chelierungsverhalten einiger trivalenter Lanthanidenionen mit biologisch aktivem 2-Hydroxy-1-naphthaldehyd-thiosemicarbazon (HNATS) mittels potentiometrischer Messungen bei 20±0.5°C in 75% (v/v) Dioxan-Wasser bei verschiedener Ionenstärke an Natriumperchlorat untersucht. Die Methode nach Bjerrum und Calvin in der Modifikation nach Irving und Rossotti wurde zur Ermittlung der Werte (mittlere Anzahl an Liganden pro Metallion) undpL (Exponent an freiem Liganden) verwendet. Die Komplexbildungskonstanten wurden in Anlehnung an Sullivan et al. an einem PC-XT Computer errechnet. DieS _min-Werte (S _min=²) wurden ebenfalls bestimmt. Die Reihung der Chelatbildungskonstanten war: La³⁺3+3+3+3+3+3+3+3+3+. Die Bildungskonstanten sind mit der Größe und dem Ionisierungspotential der Metallionen zu korrelieren.

     

钛合金（TC-6）二阶和三阶弹性常数

 用脉冲回波重叠法测量了钛合金（TC-6）的二阶、三阶弹性常数。实验中发现dμ/dp<0（p<0.17 GPa）,dμ/dp>0（p>0.17 GPa）。     

一种自制的蒸馏水器保护装置

本装置由检测、控制、执行、报警和电源五部分组成。检测部分采用了靠正常水位导通的两根信号线。当蒸馏水器在正常运行时遇停水,本装置可立即实现断电保护,同时发出声光报警,有效防止干烧,杜绝事故发生。本装置制作简便,元器件均为市售,成本低廉,性能可靠。     

Influence of hydrogen bonding on the properties of water molecules adsorbed in zeolite frameworks

Three hydrated aluminosilicate frameworks—LiABW, NaNAT, and BaEDI—are partly optimized with the periodic Hartree–Fock CRYSTAL95 code. In particular, we optimized the positions of the adsorbed water molecules including the positions of the framework cations (ABW, NAT) or part of the framework atomic positions (ABW). This allowed us to compare cation–water clusters in the gas and adsorbed states and discuss the influence of hydrogen bonding to the framework oxygen atoms or to the neighbor water molecules on the atomic properties (quadrupole coupling constant, anisotropy of electric field gradient) of the adsorbed water molecules. The LiBIK structure obtained from X‐ray diffraction is also considered to illustrate the hydrogen bonds occurring between adsorbed water molecules. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003     

An Oscillation Condition for an Electrode－separated Piezoelectric Sensor in Non－electrolyte Liquid

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Dimerization of some substituted benzoic acids in aqueous solution from conductance measurements

Precision molar conductances of benzoic, o-toluic, 2,6-dimethylbenzoic, 2,3,6-trimethylbenzoic, and, o-fluorobenzoic acids have been determined in aqueous solution as a function of temperature and of concentration up to near saturation (<0.035 M). At the higher concentrations molar conductances are found to be less than anticipated for the simple dissociation of a 1-1 electrolyte. Although the deviations are only 1% or less they have been interpreted to show that these acids are dimerized in solution. The interpretation includes an assumption that the dimer ionizes to produce a triple ion. Increasing numbers of methyl groups lead to increasing dimerization. For those acids with two ortho groups the dimerization increases with increasing temperature while the other three show decreasing dimerization with increasing temperature. Temperature functions have been determined for the dimerization constants and from these functions standard changes in enthalpy, entropy, and heat capacity have been determined. Comparisons are made with dimerization studies in non-aqueous solvents. From these as well as the behavior of benzene in water it is concluded that a major factor driving the dimerization is hydrophobic interaction. To provide a limiting conductance of the triple ion needed in the dimerization calculations a conductance study was also made for o-Phenylbenzoic acid on the assumption that its anion provides an approximate model of the triple ion.     

植物胞外钙调素与拮抗剂W7-Agarose结合作用的荧光光谱法研究

W 7-agarose是常用的细胞外CaM功能的拮抗剂,本实验采用荧光光谱法研究了水溶液中钙调素拮抗剂W 7-agarose与植物胞外钙调素的相互结合反应。W 7-agarose是一种将W 7-共价连接到颗粒型agarose(琼脂糖)的粒子。W 7-agarose颗粒较大且容易沉淀,静置5m in后,溶液中的荧光强度完全由游离的CaM产生。在溶液中加入W 7-agarose后,溶液中一部分CaM与其结合后沉降至荧光比色皿底部,导致溶液中CaM的荧光强度下降。由此可以确定溶液中游离CaM的浓度。根据公式lg{[Q]t(F0-F)/F0}=nlg{[Q]tF/F0} lgnK[B]t,从而计算出配位体系的结合常数和配比。研究表明:二者以摩尔比1∶1结合,其平衡常数为4.9×105。由此进一步计算了W 7-agarose对胞外钙调素的拮抗率,在拮抗剂W 7-agarose浓度达到15~20μmol/L时,拮抗率可达到90%以上,与文献报道的生物学体内实验结果一致,从分子水平上解释了W 7-agarose与CaM的结合作用。