A novel heterocyclic system — dihydro-2H-1,5,2,4-dioxadiazine. 2,4-Dimethyldihydro-2H-1,5,2,4-dioxadiazine hydrochloride: synthesis and NMR study

The first representative of a novel heterocyclic system, namely, 2,4-dimethyldihydro-2H-1,5,2,4-dioxadiazine hydrochloride, was synthesized.     

共沉淀CuO-ZrO2复合氧化物分散态结构研究

用XRD、EXAFS、XPS表征了共沉淀法制备的CuO-ZrO2复合氧化物的分散态结构. 500 ℃焙烧的样品在一定组成范围内形成大体均匀的无定形态固溶体. CuO含量超过其在ZrO2中溶解度时，多余的CuO以CuO晶体形式存在；当ZrO2含量超过其在CuO中溶解度时，多余的ZrO2以四方相ZrO2晶体形式存在.焙烧温度达到800 ℃时，样品由单斜相ZrO2和CuO晶体组成.     

ABS blends with phenoxy: morphology,thermal, mechanical and rheological properties

Blends of ABS (acrylonitrile–butadiene–styrene) with phenoxy(poly(hydroxyether bisphenol A)) were prepared using a Branender single screw extruder. Scanning and transmission electron micrographs (SEM, TEM) showed a typical two-phase morphology; particle-in-matrix (90/10) (ABS/phenoxy by weight), 70/30, 10/90), island/sea (30/70) and co-continuous (50/50) morphologies. The glass transition temperature (T_g) of SAN was almost unchanged in the blends, while the T_g of phenoxy increased by about 5 °C in the blends. The synergistic effect of tensile modulus and strength was noted in ABS-rich blends, where a drastic drop of ductility was seen, and the results were interpreted in terms of rubber particle migration form SAN to phenoxy phase, which was visualized by TEM. Melt viscosity showed yield in ABS-rich blends, and generally followed the log additivity.     

On the magnetic properties of Lithium Vanadium Bronzes LixV2O5

Magnetic susceptibility of V₂O₅ and of the α-, ?-, δ- and γ-Li_xV₂O₅ bronzes prepared either at high or at room temperature has been measured between liquid helium and ambient temperature. The results are representative of the localized character of the V⁴⁺ ion d-electron and, for high enough x-values, of the existence of antiferromagnetic interactions in a low dimensional system. The intrachain exchange integral J has been determined using the Bonner/Fischer model for Heisenberg chains with S = 1/2 spin. It is larger for the γ- than for the δ-phase. This result as well as the occurrence of long range ordering below T_N ≈ 130 K in the γ-phase may be ascribed to ordering of V⁴⁺ and V⁵⁺ ions in the former bronze and to the random distribution of V⁴⁺ ions in the latter one.     

层状LiMnO_2正极材料的研究进展

层状LiMnO2 化合物的研究是目前锂离子电池正极材料锂锰氧化物研究工作的新热点 ,本文综述了近年来国内外LiMnO2 化合物的研究进展 ,主要阐述了具有层状和扭曲层状结构的m LiMnO2和o LiMnO2 的结构、电性能、合成和改性方法等方面的研究状况 ,重点介绍了离子交换法合成层状LiMnO2 的原因和机理。探索新的合成方法和掺杂其它金属离子改性以提高循环性能是今后LiMnO2 的研究趋势。     

Application of symplectic algorithms to QCT calculation:H+H_2 system

The basic theory of symplectic algorithm was introduced. A comparison between Runge-Kutta method and symplectic integration method was preformed in the simulation of the long time behavior of H + H2 system on BKMP potential energy surface. Our results reveal a dis-sipative behavior in the integral of ordinary differential equation by the fourth order Runge-Kutta method, which causes incorrect simulation results in QCT calculations. However, when the symplectic integration method is applied, the dissipative behavior is not found in the same system. When the initial state is the same, the energy deviation of fourth order symplectic integral method is almost one percent of that of fourth order Runge-Kutta method in a 60000-step simulation, and that of sixth order symplectic integral method is much less. These results show that the symplectic integral methods are always the better choice in the integral calculation of the long time behavior in maintaining energy conservation.     

Synthesis of Alkylcyclophosphanes from Red Phosphorus – molecular structure of i-Pr4P4 by gas electron diffraction

A polyphosphide of the type (NaP)_X 1 was obtained from red phosphorus and sodium in presence of small amounts of naphthalene in 1,2-dimethoxyethane as solvent. 1 reacts with alkyl halides in dependence on the kind of alkyl group with formation of different alkylcyclophosphanes. As definite compounds Me₅P₅ 2 , Et₅P₅ 3 (with not definite constitution), i-Pr₄P₄ 4 and t-Bu₄P₄ 5 could be isolated. 1 was identified by X-ray diffraction, 2 – 5 by means of their ¹H, ¹³C, ³¹P n.m.r. and mass spectra. The molecular structure of 4 was identified by electron diffraction.     

N-heterocyclic carbenes as ligands in high-valent molybdenum and tungsten complexes

Oxometal complexes of molybdenum and tungsten in high oxidation states from stable adducts with 1,3-dimethylimidazoline-2-ylidene (L) 1. The first ‘carbene’ complexes of molybdenum(VI) [MoO₂Cl(L)₃]Cl (3a) and tungsten(VI) WO₂Cl₂(L)₂ (4b) are reported.     

B2O3/TiO2-ZrO2催化环己酮肟气相Beckmann重排反应研究Ⅱ.焙烧温度的影响

采用XRD、FT-IR和NH3-TPD等方法，研究了载体预焙烧温度和催化剂活化焙烧温度对B2O3/TIO2-ZRO2催化剂的结构、酸性和催化环己酮肟气相Beckmann重排反应性能的影响。结果表明，在383-773K范围内，载体预烧温度对催化剂性能的影响不大，但经973K高温预焙烧后，由于生成了ZrTiO4晶相，使其与H3BO3的相互作用减弱，从而导致催化剂的酸性和反应性能降低，提高催化剂活化焙烧温度，有利于B2O3与TiO2-ZrO2的相互作用，生成更多的Beckmann重排反应所需的中等强度酸中心，使催化剂的活性和选择性提高；但活化焙烧温度过高，会使催化剂中大量的B2O3晶粒析出，引起酸中心数量和催化活性的明显下降。