Nonlinear Optical Properties of Tri—nuclear Transition Metal Clusters M—（μ—S）s—M′（M=Mo,W;M′=Cu,Ag,Au）

The static polarizabilities and the second-order hyperpolarizabilities of a series of tri-nuclear metal cluster models MS4(M′PPh3)2(M′PPh3)(M=Mo,W;M′=Cu,Ag,Au)have been calculated within the first-principle theoretical framework. The model clusters have two fragments of rhombic units and it is the charge ransfer from one of these moieties to the other that is responsible for nonlinear optical property. This kind of electronic delocaization, differentiated from that of planar π-system, is very interesting and is worthy for further investigation.     

双质谱测定地卟啉取代基组成的解析方法及其应用

根据卟啉标样的双质谱特征，建立一种计算卟啉环上取代基组成的方法。卟啉的平均分子结构简式衡量其取代基的组成，尤其对地质体中相同碳数的卟啉“混合物”大环外取代基的构成十分有效。     

A novel method for the synthesis of the PEG-crosslinked chitosan with a pH-independent swelling behavior

In this study, a simple method was developed to crosslink chitosan using poly(ethylene glycol) (PEG) with different molecular weights. Crosslinking of chitosan was confirmed by various spectral analyses. The differential scanning calorimetric (DSC) study indicated that the rigid crystalline structure of chitosan was decreased after crosslinking with PEG. The PEG-crosslinked chitosan (PEG-Ch) showed a pH-independent swelling behavior: swelled in both the simulated stomach (pH 1.1) and intestinal (pH 7.4) solutions. The swelling ratio of PEG-Ch increased significantly with a higher molecular weight of PEG used. In contrast, chitosan dissolved completely in a simulated stomach solution and showed a comparatively less swelling in a simulated intestinal solution. Thus, the prepared PEG-Ch could be a better biomaterial than chitosan in the development of orally sustained drug-delivery devices.     

关于超高分子量聚丙烯超拉伸膜的结构性能的研究——Ⅱ.形态结构变化对力学性能的影响

用X-射线衍射、动态力学测定等手段研究了不同拉伸倍数的超高分子量聚丙烯薄膜的力学性能的变化.以X-射线衍射法并基于串联力学模型的假设得到的各样品的表观晶区模量E_c~(app)约为34-38GPa.样品模量E_b随拉伸倍数增加而逐渐增大,其变化趋势与非晶区取向因子的变化相类似,说明非晶区取向是左右样品模量的重要因素.室温下,69倍拉伸样品的模量为27GPa,约为表观结晶模量的3/4,且其值在-150-160℃的温度范围内没有急剧变化,说明超拉伸明显改善了材料的力学性能及热稳定性.在各拉伸样品中,考虑伸直链结晶生成的可能性,利用并串联力学模型对伸直链结晶的体积分数做了估算,并对X-射线衍射法所得表观结晶模量进行了修正,认为室温下聚丙烯的真正晶区模量约为47GPa.     

Chemistry of polyfunctional molecules-123. Reactions of BiBr3, SbI3 and AsI3 with LiN(PPh2)2; X-ray structure of a cyclophosphazene salt containing arsenic(I)

BiBr₃ or SbI₃ react at 20°C with LiN(PPh₂)₂ (1) to give elementary Bi or Sb and the P---P coupled phosphazene ligand Ph₂P---N=PPh₂---PPh₂=N---PPh₂ (2). The reaction of AsI₃ with 1 at room temperature formed yellow needles of the eight-membered heterocycle (3), whereas AsI₃ interacted at 80°C with 1 in the molar ratio of 1:3 to give elementary arsenic and 2. Treatment of AsI₃ and 1 at 20°C in a 1:2 stoichiometry yielded the seven-membered, cyclic arsenium(I) salt

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I·4THF (5·4THF), which was characterized by elemental analysis, conductivity, mass, IR and NMR spectroscopy and single-crystal X-ray structural analysis.     

Interaction of aminoazoles with Meldrum’s acid and dialkyl ketones or cyclohexanone

Interaction of 3-amino-5-methylpyrazole, 3-amino-5-methylthio-, and 3,5-diamino-1,2,4-triazole with Meldrum’s acid, acetone, ethyl methyl ketone, and cyclohexanone leads to alkyl-substituted pyrazolo[3,4-b]pyridin-6-ones and 1,2,4-triazolo[1,5-a]pyrimidin-7-ones respectively. The structure of 5,5-dimethyl-2-methylthio-4,5,6,7-tetrahydro-1,2,4-triazolo[1,5-a]pyrimidin-7-one was demonstrated by an X-ray structural investigation. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 595–601, April, 2007.     

Study of structural,electromagnetic and dielectric properties of cadmium substituted Ni–Zn nanosized ferrites

Sol-gel auto-combustion method was adopted to prepare Cd²⁺ ions substituted Ni–Zn nanosized ferrites having a chemical formula Ni_0.5Zn_0.5-xCd_xFe₂O₄ (0.0 $\le x\le 0.4)$. Their structural, electromagnetic, and dielectric properties were investigated by using XRD, FE-SEM, EDS, FTIR, VSM, and IS. The XRD analysis revealed a single-phase cubic structure of all samples. The addition of cadmium increased the lattice constant and cell volume of Ni–Zn ferrite due to the difference in the ionic radii between Cadmium (0.97 ?Å) and Zinc (0.74 ?Å). FESEM images showed irregularly shaped grain sizes in the range of 40 to 73 ?nm with random orientations and some agglomeration. The FTIR analysis also confirmed the presence of spinal ferrite phase functional groups in all samples. The saturation magnetization decreased (from 89.51 to 71.32 emu/g) with increasing cadmium content. However, the remanent magnetization and coercivity parameters increased with an increase in cadmium content. The dc resistivity as a function of the temperature of all samples was investigated, and the activation energies were found to be in the range of 0.48 to 0.51 ?eV. The dielectric loss decreased with increasing cadmium content. However, the dielectric constant and dielectric loss tangent (tan) varied non-monotonically with increased cadmium content.     

Synthesis and characterization of aromatic polyamides containing alkylphthalimido pendent groups

A series of polyisophthalamides containing pendent phthalimido groups and flexible side spacers were prepared from four novel diacids and three commercial aromatic diamines. These polyamides were prepared in high yields and with high molecular weights by direct polycondensation with triphenyl phosphite and pyridine as condensing agents. The weight‐average and number‐average molecular weights, measured by gel permeation chromatography, were 70,000–137,000 and 47,000–86,000 g/mol, respectively. The novel polyamides were amorphous and readily soluble and showed glass‐transition temperatures of 150–240 °C, as measured by differential scanning calorimetry. Thermogravimetric analysis showed that the 10% weight‐loss temperatures in nitrogen were 355–430 °C, a significant improvement in thermal stability having been observed with the increase in the side‐chain length. A theoretical quantum mechanical study was successfully carried out to explain these results. Flexible and tough films, cast from polymer solutions, showed tensile strengths of 50–125 MPa. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3711–3724, 2002     

利用AFM和SNOM对淋巴细胞膜表面超微结构及其光学性质的初步研究

利用原子力显微镜(Atomic Force Microscopy，AFM)对淋巴细胞表面形貌进行了形态学的初步研究，观察到了其膜表面其他显微技术所不能发现的超微结构．同时也运用扫描近场光学显微镜(Scanning Near field Optical Microscopy，SNOM)对淋巴细胞进行成像，观察了其对光的透射、吸收等光学性质，并对两种成像方法进行了比较．研究发现：淋巴细胞膜表面凹凸不平，分布着大量直径几十到几百纳米不等的小颗粒；淋巴细胞中央部位有自发荧光现象．结果表明，AFM和SNOM可作为进一步探讨淋巴细胞的结构与功能关系的有力工具．     

含聚醚间隔链的扩链脲改性环氧树脂/双氰双胺固化体系性能研究

合成了一系列含不同分子量聚环氧丙烷 (PPG)柔性间隔链的扩链脲 ,系统考察了扩链脲改性环氧树脂E 5 1/双氰双胺 (dicy)固化体系的固化反应活性、动态力学行为、冲击性能和断裂面形态结构 ,并对体系的冲击性能、形态结构与动态力学行为之间的关系进行了探讨 .结果表明 ,改性体系固化反应活性明显提高 ,固化反应表观活化能降低 ,固化反应峰顶温度从 190℃降低至 14 0℃ ,固化反应的表观活化能由 14 5 5kJ/mol降至 70～ 80kJ mol;改性体系冲击强度明显提高 ,其中所含PPG柔性链分子量为 10 0 0的扩链脲改性的E 5 1/dicy体系冲击强度较未改性的E 5 1/dicy体系提高了 8倍 ,其冲击试样断裂面的形态具有明显的韧性断裂特征 ,微观两相网络结构的存在导致了改性体系冲击强度显著提高