超临界NaCl水溶液的分子动力学模拟

采用分子动力学模拟的方法对超临界NaCl水溶液的微观结构进行了研究.模拟发现在所研究超临界条件下,密度的变化比温度的变化对超临界NaCl水溶液的微观结构影响更大.温度及密度对Cl－ H2O径向分布函数的影响比对Na＋ H2O径向分布函数的影响要大.超临界条件下,各gNa＋－Cl－在0.261 nm处出现峰值,表明Na＋、Cl－之间发生了离子的缔合.超临界条件下,随温度增加,缔合作用增强；随密度增加,缔合作用减弱.本文工作为建立可适用于超临界条件下的电解质热力学模型提供了依据.     

Coating Carbon Nanotubes with Europium Oxide

Carbon nanotubes (CNTS) coating with europium oxide by a simple method is reported in this letter for the first time. The CNTS were refluxed in a solution of nitric acid containing europium nitrate, and the pH value was subsequently ajusted with ammonia solution. At last, the mixture was filtered and annealed. The TEM micrograph showed that the CNTS were covered with a uniform thin layer with thickness of about 15 nm. The XRD results revealed that the CNTS were coated with europium oxide.     

Synthesis and Characterization of Novel Polyimides Based on Pyridine-containing Diamine

A new aromatic diamine monomer containing pyridine unit, 2,6-bis （4-aminophenoxy- 4＇-benzoyl）pyridine（BABP）, was synthesized in three steps, starting from 2,6-pyridinedicarboxyl chloride. A series of novel pyridine-containing polyimides were prepared v/a the polycondensation of BABP with various aromatic dianhydrides through poly（amic acid） precursors, and thermal or chemical imidization of the precursors. The polyimides exhibit desirable properties, e.g., good solubility in N-methyl-2-pyrrolidone and m-cresol, excellent thermal stability and film-forming capability, as well as high inherent viscosity, indicating high molecular weight.     

Xyloketal G,a Novel Metabolite from the Mangrove Fungus <Emphasis Type="Italic">Xylaria sp.</Emphasis> 2508

A novel metabolite 1, named xyloketal G, was isolated from cultures of marine derived mangrove fungus Xylaria sp. 2508. Its structure was elucidated by analysis of spectroscopic data.__________Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 22–23, January–February, 2005.     

Selective bonding of pyrazine to silicon(100)-2x1 surfaces: the role of nitrogen atoms

The covalent binding of pyrazine on Si(100) have been investigated using high-resolution electron energy loss spectroscopy (HREELS) and x-ray photoelectron spectroscopy. Experimental results clearly suggest that the attachment occurs exclusively through the bonding of the two para-nitrogen atoms with the surface without the involvement of the carbon atoms, as evidenced from the retention of the (sp2) C-H stretching mode in HREELS and a significant down shift of 1.6 eV in the binding energy of N 1s. The binding mechanism for pyrazine on Si(100) demonstrates that reaction channels for heteroatomic aromatic molecules are strongly dependent on the electronic properties of the constituent atoms.     

Ar n HF van der Waals clusters revisited. I. New low-energy isomeric structures for n=6-13

New low-lying isomeric structures of Ar(n)HF clusters are reported for n=6-13. They were determined using simulated annealing and evolutionary programming, for pairwise additive intermolecular potential energy surfaces. New global minima were found for the clusters with n=7, 10, 11. The new lowest-energy structure of Ar(7)HF and several new local minima for n=6, 7 clusters have the HF bound on a threefold surface site, consistent with the recent spectroscopic data for Ar(n)HF clusters in helium nanodroplets. A new type of low-energy local minima were determined for n=9-13 clusters.     

Novel hydrogen-bonded three-dimensional network complexes containing cobalt-pyridine-2,6-dicarboxylic acid

The novel complex, Co(H₂O)₅[Co(2,6-pydc)₂] (1) has been prepared in aqueous solution and characterized by single-crystal X-ray diffraction, elemental analyses and i.r. spectra. X-ray structural analysis revealed that three novel compounds each possess both – stacking and hydrogen-bonding interaction three-dimensional (3-D) networks.     

Self-assembled multivalent vancomycin on cell surfaces against vancomycin-resistant enterococci (VRE)

A vancomycin (Van) derivative self-assembles in a phosphate buffer as a divalent Van and on cell surfaces as a multivalent Van, which offers potent activity against VRE.