Trace determination of cobalt ion by using malic acid-malonic acid double substrate oscillating chemical system

A novel kinetic method for determination of trace amounts of cobalt ion was proposed and validated. The method is based on adding malic acid into classical Belousov-Zhabotinskii （B-Z） oscillating chemical system to form a double substrate one. The results showed that when the concentration of cobalt ion was in the range of 5.27× 10^-8 to 5.37 × 10^-12 mol L^-1, the change of the oscillating period was directly proportional to the negative logarithm of cobalt ion concentration. The sensitivity and precision of the developed method were quite satisfactory. The limit of detection was down to 5.20 × 10^-13 mol L^-1 which was a highest sensitivity found for determination of metal ions using oscillating chemical reaction so far. Some factors influencing the determination were also examined. The method has been successfully used to determine cobalt ion in vitamin B12 injection.     

Localized electron traps on extended molecular surfaces

We have previously alluded to the fact that concentrated charge pockets can form on molecular surfaces that can act to stabilize excess electrons. These charge pockets are formed from systems, which posses a network of hydrogen bonded OH groups on one side of the surface and hydrogen atoms on the opposite side of the molecular surface. In this work, we have increased the size of our recently reported molecular surfaces (Jalbout and Adamowicz, Mol Phys, 2006, 19, 3101) while keeping the number of OH groups constant, to investigate localized charge concentration on extended frameworks. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

Can Fluorinated Molecular Cages Be Utilized as Building Blocks of Hyperhalogens?

Based on the density functional theory for exchange‐correlation potential, fluorocarbon molecular cages are investigated as building blocks of hyperhalogens. By utilizing C₈F₇ as a ligand, a series of hyperhalogen anions, that is, M(C₈F₇)₂^? (M=Li, Na, and K) and M(C₈F₇)₃^? (M=Be, Mg, and Ca), are modeled. Calculations show that all the C₈F₇ moieties preserve their geometric and electronic integrity in these anions. These anionic molecules possess larger vertical electron detachment energies (5.11–6.45 eV) than that of C₈F₇^?, verifying their hyperhalogen nature. Moreover, it is also revealed that using larger fluorinated cage C₁₀F₉ as ligands can bring about hyperhalogen anions with larger vertical electron detachment energies. The stability of these studied anions is determined by their large HOMO–LUMO gaps and positive dissociation energies of predetermined possible fragmentation pathways. It is hoped this study will provide an approach for the construction of new types of hyperhalogens and stimulate more research in superatom chemistry.     

Recent Advances in Self‐Oscillating Polymer Material Systems

In 1996, we first reported self‐oscillating polymer gels exhibiting autonomous swelling‐deswelling oscillations driven by the Belousov‐Zhabotinsky reaction. In contrast to conventional stimuli‐responsive gels, the self‐oscillating gel can autonomously and periodically change its volume in a closed solution without any external stimuli. Since the first report, the novel concept of self‐oscillating gels has been expanded into various polymer and gel systems. Herein, we summarize recent advances in self‐oscillating polymers and gels.     

Vertical excitation energies for ribose and deoxyribose nucleosides

Vertical excitation energies for DNA and RNA nucleosides are determined with electron structure calculations using the time-dependent density functional theory (TDDFT) method at the B3LYP/6-311++G(d,p) level for nucleoside structures optimized at the same level of theory. The excitation energies and state assignments are verified using B3LYP/aug-cc-pVDZ level calculations. The nature of the first four excited states of the nucleosides are studied and compared with those of isolated bases. The lowest npi* and pipi* transitions in the nucleoside remain localized on the aromatic rings of the base moiety. New low-energy npi* and pisigma* transitions are introduced in the nucleosides as a result of bonding to the ribose and deoxyribose molecules. The effect on the low-lying excited state transitions of the binding to phosphate groups at the 5'- and 3',5'-hydroxyl sites of the uracil ribose nucleoside are also studied. Some implications of these calculations on the de-excitation dynamics of nucleic acids are discussed.     

A new approximate method for second order elliptic problems with rapidly oscillating coefficients based on the method of multiscale asymptotic expansions

In this paper, we consider second order elliptic problems with rapidly oscillating coefficients. On basis of [O.A. Oleinik, A.S. Shamaev, G.A. Yosifian, Mathematical Problems in Elasticity and Homogenization, North-Holland, Amsterdam, 1992; Wen-ming He, Jun-zhi Cui, A pointwise estimate on the 1-order approximation of , IMA J. Appl. Math. 70 (2005) 241-269] we propose a new approximate method to solve these problems. Of course, we present its error estimate.     

A necessary and sufficient condition for the oscillation of solutions of Liénard type system with multiple singular points

In this paper, a necessary and sufficient condition for the solution of Liénard type system with multiple singular points to oscillation under the more general assumption is given. Results of the papers [14] are also extended and improved in this paper.Project supported by Science Foundation of Education Bureau of the Metallurgy Ministry, P. R. China     

蔗糖水解Belousov－Zhabotinskii体系化学振荡现象

自从1972年Field等据丙二酸为底物的Belousov-Zhabotinskii(BZ)反应提出T著名的FKN机理以来,人们发现了许多与生化过程有关的化学振荡体系并应用于临床实践.机体在新陈代谢过程中,糖元的糖酵解反应是以糖类为基础的复杂化学振荡,考虑到代谢过程,糖类分解有许多中间物的振荡.     

非线性振动系统动力学行为的实验研究

本文综述了非线性振动系统动力学行为的实验研究,详细叙述了机械模型实验,实验数据的分析与处理,并对今后发展趋势作了述评．