CoFe2O4自形成磁性液体场致结构化对磁化的影响

The Langevin paramagnetic theory can’t describe the relation between magnetization of ferrofluids and applied magnetic field. The structuralization of ferrofluids, which is considered the main influence factor of the magnetization, is regarded. The part of magnetization works is deposited when the structure is forming. This action influences the magnetization of ferrofluids directly or indirectly. On the base of the “compressing” model, the Langevin function that usually describes the magnetization of ferrofluid is modified, and a well-fitted curve is obtained. An equation of the relation between the equivalent volume fraction after being “compressed” and the intensity of magnetic field is discovered, which approximately describes the process of magnetization. The relation between the approximate initial susceptibility and the volume fraction can be obtained from modified formula.     

A NOVEL APPROACH TO RHEOLOGICAL CHARACTERIZATION FOR THE GELATION IN POLYMER CRYSTALLIZATION

The isothermal crystallizations of three kinds of commercial isotactic polypropylene have been studied by DSC and rheometric experiments, in a range of temperatures where the rate of crystallization is moderate. As the crystallization proceeds, volume contraction induces tensile force upon the parallel plates. The tensile force relaxed quickly in liquid states,but after a critical amount of the relative crystallinity, it starts to accumulate in the static test, that is, with the motionless parallel plates. A new method to determine the liquid-solid transition by the static tensile force is proposed and compared with two dynamic methods of detecting liquid-solid transition, that is, the power-law modulus theory and the yield modulus model. The tensile force method predicted considerably earlier transition than the dynamic methods, and the corresponding DSC data indicate relative crystallinity of larger than 0.2 at the transition times. The limitation of dynamic methods and other possible errors have been analyzed. While the dynamic methods are suitable for slow crystallization, the tensile force method is more appropriate for the crystallization of moderate rates. Moreover, it has the advantage of almost not disturbing the crystallizing materials before the transition.     

碱性介质中葡萄糖在铂电极上的阳极氧化

为了进一步探明葡萄糖在铂电极上的氧化机理,用循环伏安法(CV)在-0.9～0.4 V(相对于饱和甘汞参比电极)内研究了葡萄糖在铂电极上催化氧化行为,首次详细报道了葡萄糖在电化学氧化过程中的电位振荡现象,并用电流扫描法表征了葡萄糖的电位振荡情况.电流扫描结果表明,在较慢的电流扫描速度下,电极过程出现了明显的电位振荡.说明电极上产生了毒化中间物,电位振荡是由于毒化中间物在电极上的吸附和在高电位下氧化除去引起的.     

分子线电子输运特性的第一性原理研究

从第一性原理出发,利用密度泛函理论研究了SH-C8H16-SH分子和金表面的相互作用,并利用分子前线轨道理论和微扰理论定量地确定了该相互作用能常数,然后,利用弹性散射格林函数方法研究了该分子与金表面形成的分子线的伏-安特性.研究结果表明,当含有硫氢官能团的有机分子化学吸附于金表面时,硫原子将与金原子形成以共价键为主的混和键,此时,扩展的分子轨道使分子线的电导呈现出欧姆特性,而对于局域的分子轨道,电子的输运只能通过隧道效应来实现.对分子线伏-安特性的计算结果显示,在零偏压附近,存在一个电流禁区,随着偏压的增加,分子线的电导呈现出平台特征.     

Thermoelectric Properties of Czochralski GeSi Crystal

In order to discuss the application possibility of SiGe crystal in thermoelectric materials,we investigated the thermoelectric properties of several silicon-germanium alloys with different content,orientation and electric conductive type. As discussed in the experiment result,the absolute value of Seebeck coefficient fluctuates from 300 to 600 μV/K in the whole temperature range. In the present paper,the relationship of Seebeck coefficient against content,orientation and electric conductive type is summarized in detail. The Seebeck coefficient of the sample with <111> orientation is smaller than that in <100> at the same temperature. Absolute value of P-type is larger than that of N-type except pure Ge. But as the temperature increases,the absolute value of pure Ge decreases many times as quickly as that of other specimens. In addition,the specimens of bulk GeSi alloy crystals for experiment were grown by the Czochralski method through varying the pulling rate during the growing process.     

PHONONS IN POLYACENIC CHAINS

We have theoretically resolved phonon excitations in quasi-two-dimensional organic crystals of polyacenic semiconductor material which may be obtained by the pyrolytic treatment of phenol-formaldehyde resin. A model for studying the dynamical properties using three polyacene chains is proposed with the aim to present the vibrational properties of this structure. It employs the formalism of solid states in two dimensions which admit phonons. A simulation process of the two-dimensional lattice structure shows that elastic waves may explain the existence of vibrational modes in the frequency range 100-400 cm-1. The presence of acoustic and optical like phonons is discussed in terms of the elastic force constants. A hyperfine resonance structure is obtained. It allows the analysis of the dynamical evolution in thin films of polyacene. It is found that the behavior of the phonon density of states exhibits resonance between modes in the structure.     

SYNTHESIS OF POLY（3,4-AZOPYRIDYLENE） AND OXYGEN-BINDING AFFINITY OF ITS COMPLEX WITH COBALTPORPHYRIN

Synthesis and characteristics of poly(3,4-azopyridylene) (PAP), conductivity and oxygen-binding affinity of its complex with meso-α,α,α,α-tetrakis(o-pivalamidophenyl) porphyrinatocobalt(Ⅱ) (CoP) were studied. PAP was prepared by oxidative polymerization of 3,4-diaminopyridine (DAP) in DMF solution using CuCl/pyridine as the catalyst. IR and NMR results showed that the peak of amido group in DAP was converted to the azo group in PAP and a π conjugated polymer was synthesized. The average molecular weight of PAP was determined to be 5.0 × 103. The PAP-CoP complex was prepared by complexing the pyridyl group of PAP with the fifth coordination site of CoP in DMF solution. In comparison with the CoP complex with a non-π conjugated polymer, the PAP-CoP complex shows good electroconductivity of 5.8 × 10-6 Scm-1. The PAP-CoP complex displays a reversible change in the UV-Visible absorption spectrum from the deoxy form to the oxy or oxygen-binding one with an isosbestic point, in response to the partial oxygen pressure of the atmosphere. The oxygen-response behavior was monitored at the absorbance ascribed to the oxy form at 548 nm to give the oxygen-binding affinity.The oxygen-binding equilibrium curves of PAP-CoP complex obey a Langmuir isotherm. DMF has great effects on the oxygen-binding properties of the PAP-CoP complex. The oxygen-binding affinity of PAP-CoP complex in the solid state is higher than that in DMF solution. With decreasing temperature, the oxygen-binding affinity of the PAP-CoP complex increases.     

液晶聚合物/柔性链聚合物共混体系相分离形态

利用元胞动力学方法在二维情况下对浓度、取向序参量的含时Ginzberg-Landau方程进行数值求解,研究了液晶聚合物/柔性链聚合物共混体系的相分离动力学,考察了浓度、取向有序过程的耦合对相分离形态的影响.结果表明,此耦合作用对相分离的时间进程以及相分离图样的空间排布都有影响.液晶聚合物的取向有序相当于增加了两组分间的不相容性而促进两相分离;两个序参量在热力学方面的耦合使液晶聚合物趋向于沿着界面方向取向,而动力学方面的耦合使液晶聚合物分子沿着其取向方向扩散,相分离图样的空间排布由这两种效应共同决定通过极化率张量的定义用数值方法模拟得到了相分离体系的小角光散射图样,结果表明,散射强度分布具有方位角依赖性,它是由浓度、取向序参量的空间变化共同决定的.     

氢气在炭狭缝微孔内吸附的预测

通过边界的平均场近似,推导二平板狭缝孔格子理论Ono-Kondo吸附等温方程.利用格子气模型特性和微观物理学理论,计算氢分子在石墨平面的最大吸附容量.比较由氢分子在石墨平面二典型聚集状态标定的Ono-Kondo方程,并用预测精度较高的方程计算了与文献相同条件下的吸附等温线.在比较了计算结果、试验结果和GCMC分子模拟结果后,对Ono-Kondo吸附等温方程的特点、理论基础作了分析,指出了方程的适用范围.     

PROPERTIES AND MORPHOLOGY OF UNSATURATED POLYESTER/ACRYLATE-TERMINATED POLYURETHANE/ORGANOMONTMORILLONITE NANOCOMPOSITES

Unsaturated polyester resin （UPR）/acrylate-terminated polyurethane （ATPU）/organo-modified montmorillonite （OMMT） nanocomposites were prepared by the in situ intercalative polymerization method. Samples were prepared by the sequential mixing, i.e. mixture of the ATPU and styrene （S） and OMMT were prepared in the first step; UPR was then added to the pre-intercalates of ATPU/S/OMMT. Results indicate that the mechanical properties and thermal properties of UPR/ATPU/OMMT nanocomposites greatly depend on the amount of ATPU and OMMT. Results show that the addition of ATPU could increase the impact strength of UPR/ATPU composites, but the tensile strength, flexural strength and heat resistance of the materials are obviously decreased. When the weight ratio between UPR, ATPU and OMMT were 82：15：3, the impact strength and heat distortion-temperature of nanocomposite were greatly improved, meanwhile there was little change for other properties of the nanocomposites. The synergistic enhancement effects of ATPU and OMMT on the composites were observed. The structures and morphology of the composites were investigated by X-ray diffraction, scanning electron microscopy and transmission electron microscopy.     

DFT Studies on Non-IPR C68 and Endohedral Fullerene Sc3N@C68

The structures and spectra of 20 possible isomers of C78(CH2)3 have been studied by using AM1,INDO/CIS and DFT methods. The results show that the most stable isomer is 1,2,3,4,5,6-C78(CH2)3 (A) with annulene structures,where three -CH2 groups are added to the 6/6 bonds located at the same hexagon passed by the shortest axis of C78 (C2v). Compared with that of C78 (C2v),the first absorption in the electronic spectrum of C78(CH2)3 (A) is blue-shifted because of its wider LUMO-HOMO energy gap. While the IR frequencies of the C–C bonds on the carbon cage are red-shifted owing to the formation of annulene structures and the extension of the conjugated system. The chemical shifts of the carbon atoms in 13C NMR spectra are moved upfield upon the addition.     

LOW DENSITY POLYETHYLENE/CLAY NANOCOMPOSITES MODIFIED BY ETHYLENE COPOLYMERS： EFFECTS OF FUNCTIONALIZED SEGMENTS ON MORPHOLOGY

Melt extrusion was used to prepare binary nanocomposites of ethylene copolymers and organoclay and trinary nanocomposites of low-density polyethylene （LDPE）, ethylene copolymer and organoclay. X-ray diffraction （XRD） and transmission electron microscopy （TEM） were used to analyze the structure of the clay phase and the morphology of the nanocomposites. Influences of the comonomer in the copolymer and the content of the copolymer on the morphology of the resulting nanocomposites were discussed. The binary and the trinary composites may form intercalated or exfoliated structures depending on the interaction between the copolymer and the clay layers and the content of the copolymer.     

Dilatometric study of glass transition kinetics in polyisoprene

From dielectric measurements the thermal dependence and the distribution function of the relaxation times can be determined. In the present contribution we are testing the correspondence between the relaxation times obtained from the dielectric measurement and the dilatometric behavior of the material in the vicinity of the glass transition temperature. The experimental data used for the comparison were obtained for the sample of polyisoprene.     

交流电沉积法制备金属氧化物纳米材料及形貌控制

以不同种类的金属丝为电极,采用交流电沉积的方法在液相水溶液中制备了多种金属氧化物纳米材料,并对其形貌进行了控制.由XRD和TEM分析结果表明,在相同的NaCl电解质水溶液中,不同的金属电极对应的不同金属氧化物纳米产物具有明显不同的形貌.     

二氧化碳和丙烯直接合成甲基丙烯酸的NiPMo/TiO2催化剂的研究

用溶胶-凝胶法以磷钼酸(MPA)的镍盐溶液水解钛酸四丁酯制备了NiPMo/TiO2催化剂.使用ICP、 XRD、 TG-DTA、 IR、 TPD-MS和微反应技术研究了催化剂的化学组成、热稳定性、化学吸附性质和催化反应性能.杂多钼酸盐与TiO2通过O2-在TiO2表面发生了键合.在623 K下,杂多阴离子仍保持原有的Keggin结构.CO2在Lewis酸位Ni(Ⅱ)和Lewis碱位Ni-O-Mo的桥氧协同作用下生成CO2卧式吸附态Ni(Ⅱ)←O-(CO)←(O--Ni).丙烯有多种吸附态在催化剂上吸附.在563 K、 1 MPa和空速1500 h-1的反应条件下,丙烯的摩尔转化率为3.2%,产物MAA选择性为95%.     

压力溶弹溶样石墨炉原子吸收法测定硫磺中的砷、硒、碲

建立了硝酸压力溶弹溶样、石墨炉原子吸收法测定硫磺中砷、硒、碲元素的方法。通过正交试验确定样品的溶解条件，选择适当的基体改进剂和最佳的石墨炉升温程序，一次溶样即可实现砷、硒、碲三种元素的检测。该法的回收率为90．0％～110．0％，测定结果的相对标准偏差为2．5％～4．8％。     

甘氨酸燃烧法合成纳米ZnO-MgO及其紫外光发射

ZnO-MgO nanocomposite was prepared by glycine nitrate combustion method.Its photoluminescence property, the structure and annealing temperature dependence was studied by XRD, FTIR and SEM. The results show that the photoluminescence property of ZnO-MgO nanocomposite is greatly improved compared with that of pure ZnO. Under 325 nm laser excitation, the emission spectra of the 900 ℃ treated composite sample had an obviously enhanced ultraviolet (UV) band centered at 385 nm at room temperature. The luminescence intensity of the UV band became stronger with the increase of annealing temperatures and reached a maximum at 900 ℃ but decreased at 1000 ℃. The photoluminescence intensity was mainly affected by the grain size, the crystallization and the action between ZnO and MgO nanoparticles. In addition, an appropriate G/N value was favorable for improving the UV-PL properties of the nanocomposite samples.     

耦合生物细胞体系中噪声诱导钙信号的传递和增强

Dynamics of calcium oscillation in a coupled cell system is discussed. It shows that when one end of the cell chain is perturbed by noise, the signal induced by noise can propagate along a linearly coupled cell chain with considerable enhancement, a rather ordered internal signal can be obtained on the other end, and the signal itself can also be enhanced. The effects of coupling constant, noise intensity and coupling means on the propagation of the signal are investigated. It is found that there exist an optimal coupling constant and noise intensity in favor of the signal propagation. What′s more, a qualitative explanation via the signal and the noise background is given. And the one way coupling is better for the signal propagation and enhancement than for the two way coupling. The results may have important applications in living cell systems, where information is transmitted along a cell chain.     

核因子κB活性抑制剂定量构效关系

The electronic structures, geometric structures and some molecular properties (generalized structural indexes) of quinazoline derivatives were computed by using density functional theory and molecular mechanism methods to investigate the quantitative structure-activity relationship (QSAR) of the inhibitory activity toward the nuclear factor kappa B. Via a stepwise regression analysis, some main factors affecting the activity of the compounds were factored out, and then the QSAR equation was effectively established. It was found that the hydrophobic parameter of the substituent on ring D is the main factor affecting the inhibitory activity of the compound. The analysis indicated, the larger the hydrophobic parameter, the higher the inhibitory activity of the compound. In addition, the net charge of the first atom and the stereoscopic parameter (MR1) of the substituent R1 on A-ring as well as the net charge of C3 are closely correlated with the inhibitory activity of the compound. In order to test the predicted results of the QSAR equation, we adopted the “leave one out” cross-validation , and found that the calculated coefficient q2 was rather high and the predicted results were both accurate and reliable. Such facts show that the obtained equation has great predictive ability. The above results can offer an important theoretical guide in the search for new quinazoline derivatives with higher inhibitory activity, and in an analysis of their action mechanisms. It is noteworthy that this scheme would be very advantageous in factoring out precursors with excellent inhibitory activity via the computer ADDIT molecule-design, since all parameters in the QSAR equation are computable and controllable.