高性能刷状ZnO介晶的制备及其对复合树脂性能的增强作用

无机填料作为齿科复合树脂的主要成分,对其性能影响最为显著。本文以阿拉伯胶为结构导向剂,用热水解法合成了多孔、分级结构的刷状ZnO介晶,其厚度和直径分别为1.2 μm和1.0 μm。通过微流控制法在其表面包覆了4~6 nm无定形SiO₂,以利于其表面硅烷化。通过场发射扫描电镜(FE-SEM)、X射线衍射仪(XRD)、热重分析仪(TGA)等对其进行了表征。对ZnO@SiO₂进行硅烷改性处理后,将其作为辅助填料,与改性纳米SiO₂主填料一起添加到Bis-GMA/TEGDMA树脂体系中,光固化得到齿科复合树脂。力学测试表明,ZnO@SiO₂填充质量分数控制在5%以内时可有效提高复合树脂力学性能。与单一二氧化硅填料的复合树脂相比,添加填充质量分数3% ZnO@SiO₂,复合树脂的力学性能表现最佳,其弯曲强度、弯曲模量和压缩强度分别提高了12.9%、6.6%和3.7%,同时还表现出优良的抗菌活性,对变异链球菌抗菌率达98.7%。此外,添加了ZnO@SiO₂介晶填料的复合树脂还具备更好的耐磨性。     

酞菁氯镓复合凝胶玻璃的谱学性能研究

采用溶胶-凝胶(Sol-Gel)湿化学工艺将酞菁氯镓(GaPcCl)掺入二氧化硅(SiO₂)凝胶玻璃基质,制备出均匀掺杂的GaPcCl复合凝胶玻璃,并对复合体系的红外光谱(IR)、紫外-可见吸收光谱(UV-Vis)及荧光光谱等谱学性能进行了测试。结果表明：GaPcCl的掺杂对凝胶玻璃基质的红外光谱没有产生显著影响;掺杂GaPcCl在复合体系中二聚体吸收峰的强度较其DMF溶液有所增大;掺杂GaPcCl在复合体系中荧光强度随浓度的增加远大于DMF溶液。     

四氢萘热解反应机理研究

本文应用计算机研究四氢萘裂解反应机理, 计算结果表明文中所提出的反应机理有仅从定性, 而且从定量上与实验结果比较符合。本文应用灵敏度分析不仅得到最合适的机理步骤, 同时还得到一些实验中或计算中难于准确得到的动力学参数。     

激光-时间分辨荧光法测定U3O8中痕量硼

本文提出了一种测定U3O8中痕量硼的激光-时间分辨荧光法, 在适当介质中, 用小型氮分子激光器激发硼与二苯甲酰基甲烷配合物的荧光, 发现此配合物的荧光寿命为2ms, 它比铀的荧光寿命长得多, 从而可将荧光的时间分辨技术应用于铀中硼的测定, 不经分离基体铀即可进行测定, 方法简单而快速, 检测下限达到0.02ng.mL^-^1(硼),当取样10mg铀时, 能测定0.01ppm的硼。用本法分析了含量在0.04-0.5ppm几个U3O8样品, 结果与其他方法相符。     

Thermoelectric Coefficients of Silicon MOSFETS in Quantizing Magnetic Field

The phonon drag and electron diffusion contribution to the tensor M which determines 3 the heat flux U = M·E is calculated for a silicon MOSFETS in a perpendicular magnetic field B. We used nearly the same theoretical formalism as Ref [6], but improvements are made in several respects. First of all the dielectric function of Fermi-Thomas approximation which has been proved to result in overscreening of the interaction is replaced by rigorous Lindhard-type dielectric function to take account of the screening between electrons and phonons. Secondly the contributions of localized electrons are separated from those of the free state electrons which are the only part that contributes to both conductivity tensor and magnetothermopower tensor. The calculated M_yx and S_xx reveal magneto-oscillationsoriginating Gom oscillations in the density of states at the Fermi level. At T = 5.02 K, our new results show that the diffusion components of thermopower are negligibly small compared with those due to phonon drag. All the theoretical values of M_yx, S_xx and S_yx are in accordance with the experimental data better than previous theoretical results.     

A Simple Method for Calculating Exciton Binding Energies in Semiconductor Quantum wires

We present a simple, general method for calculating the binding energies of excitons in semiconductor quantum wires. The binding energy is given by an integral (over the electron and hole two-dimensional coordinates perpendicular to the wire) of a prescribed function weighted by the squares of the electron and hole subband envelope functions. Taking as an example, we calculate the binding energy of exciton in quantum wires assuming an infinite confining potential. This method should be applicable to a variety of more complex systems.     

热动力学的研究(XXlV)——等浓度三级反应的热动力学

本文根据热动力学的基础理论,建立了等浓度三级反应的无量纲参数法,并用此法研究了甲醛与氨反应的热动力学.实验测得的速率常数与文献值吻合.     

Possible Phenomenological Indication for the String Coulomb Term and the Color Screening Effects in the Quark-Antiquark potential

The string Coulomb term in the quark-antiquark potential which is due to the transverse. vibrations of the flux tube in the string picture is discussed. Possible phenomenological indication evidences for this term and the color screening effects are studied by examining its spin-dependent effects on both the fine and hyperfine splittings of the P wave charmonium states.     

角分辨飞行时间法研究GaAs(100)表面蚀刻反应动力学

采用探测室可转动的分子束实验装置,研究了氯分子束与GaAs(100)表面热反应和紫外激光诱导反应的动力学.结果表明,热反应的主要产物为GaCl~3, 其角分布可用cos^2^.^3θ函数拟合.对于紫外(355nm)激光诱导反应,由角分辨的飞行时间(TOF)法测得主要产物为GaCl等,它们的通量角分布须用双余弦加和公式(c~1cosθ+c~2cos^nθ)拟合,表示产物粒子在表面法线方向明显聚集,而且由TOF 谱求得粒子的动能在表面法线方向最大. 这种明显的聚集现象可以由激光诱导的粒子在表面附近发生碰撞效应来解释     

二维聚硫杂酞菁铜的合成与性质

以四氰基-1,4-二噻英为原料,分别用无溶剂法和溶剂法合成了平面稠合型网状聚硫杂酞菁铜PCuS~8Pc(A)和(B),经元素分析,热谱,IR, 电子吸收与发射光谱表征.PCuS~8Pc具有光敏性和本征半导体性能,σ~2~9~8~K(A):2.29×10^-^6Ω^-^1 ·cm^-^1,(B):5.83×10^-^6Ω^-^1·cm^-^1