THE CORRELATION EFFECT ON THE CHAIN MOTION CONTRIBUTION TO IONIC TRANSPORT IN POLYMER ELECTROLYTES

The ionic transport process in polymer electrolytes (such as polyethylene oxide) wassimulated numerically on a two dimensional square lattice where charge carriers areaccommodated by the lattice sites connected randomly with available bonds to represent theamorphous chain configuration. Following the dynamic bond percolation theory(DBPT),the chainmotion contribution to the ionic conduction was incorporated via periodical renewal of the randombond configuration. To check and extend the prediction made by DBPT employing global abruptbond renewal,spatial correlation of the bond reassignment was introduced to the system by: 1)regional bond renewal and 2) organized bond motion. It is found that the difference between thediffusivities simulated involving regional bond renewal and those of DBPT becomes negligiblewhen the bond renewal rate approaches the carrier hopping rate.     

Studies on synthesis and molecular dynamics simulation of dendrimers containing amino acids and peptides

A series of poly(ether-amide) dendrimers with amino acids and peptides as the peripheral functional groups was synthesized, and their structures were confirmed by nuclear magnetic resonance (NMR) and electrospray ionization-mass spectrometry (ESI-MS) spectrometry. Molecular dynamics simulation of the peptide dendrimers in solution was performed, indicating that, the prior conformations of the dendrimers were atom number dependent, i.e., with the increases of the atom number, the prior conformations were more spherical. Also, the amino acid α-C atom radial distribution indicated that, with larger peripheral groups, more back-folding of the dendrimers occurred. __________ Translated from Acta Chimica Sinica, 2007, 65(1): 21–26 [译自: 化学 通报]     

Quantum chemistry study on B32 and B32H2–32

The structures of B32 and B₃₂H^2–₃₂ with I_h symmetry have been investigated by means of ab initio calculations at STO-3G level. The relationship between molecular orbitals of them has been analyzed and their bonding properties have been discussed. Then the possibility of their existence, as well as the similarity and difference between B₃₂ (B₃₂H^2–₃₂) and C₆₀ (C₆₀H₆₀) have been inferred.     

盐卤硼酸盐化学 Ⅻ. MgO·3B2O3·7H2O的热行为和脱水动力学

通过对合成MgO·3B2O₃·7H₂O的热分析研究确定热脱水反应的阶段、温度和产物,给出脱水过程的热化学反应方程式.利用甲醇、水与三氧化二硼之间的酯化反应进行相分离,确定该化合物高温结晶化产物的物相组成为晶态六硼酸镁(2MgO·3B₂O₃)和无定形B₂O₃.对该化合物的TG和DTG数据进行处理结果,给出了相应的非等温热脱水反应动力学方程.     

Cyclodextrins with heterocyclic substitution as GC stationary phases

Summary Two new cyclodextrin (CD) derivatives, heptakis{2,6-di-O-pentyl-3-O-[3′-(2″-chloro-4″,5″-dioxylmethene)-phenyl-5′-iso-oxazolylmethyl]}-β-CD (CD I) and heptakis{2,6-di-O-methyl-3-O-[3′-(2″-chloro)-phenyl-5′-iso-oxazolylmethyl]}-β-CD (CD II) were synthesized and coated on fused-silica capillary columns. Their chromatographic characteristics, including column efficiency, polarity, selectivity and phase transition were studied and compared with similar β-CD stationary phases. It was found that the heterocycle group has a significant effect on the selectivity of the CD stationary phases. Both stationary phases can be successfully used to separate many di- and trisubstituted benzene positional isomers and show stronger separation ability in separating low-polarity benzene positional isomers than other β-CD stationary phases.     

On the interaction of solitons for a class of integrable systems in the spacetime R n+1

A class of integrable systems of nonlinear partial differential equations in the spacetime R ⁿ⁺¹ is introduced. Single and multi-soliton solutions are constructed by using the Darboux matrix method. It is proved that as t±, a k multi-soluton solution splits asymptotically into k single solitons. Moreover, the interaction between solitons is elastic if we consider their magnitudes only.The work is C. H. Gu supported by the Chinese National Program for fundamental research nonlinear science.     

Large third-order nonlinear optical properties of C70 fullerene in the infrared regime

The nonlinear third-order optical susceptibility of C₇₀ in a toluene solution is measured for the first time by the method of degenerate four-wave mixing using 10 ns laser pulses at 1.06 m. The third-order susceptibility X _in ⁽³⁾ is 5.6×10^–12 esu for a C₇₀ toluene solution at a concentration of 0.476 g/l. The correspondent magnitude of the hyperpolarizability ₁₁₁₁ of the C₇₀ molecule is 1.2×10^–30 esu which is in a good agreement with the prediction given by the model of a free electron in a spherical box.