GD-MS法和ICP-MS法测定高纯铌中痕量元素

采用辉光放电质谱法(GD-MS)对高纯铌中Ta,Mo,W等痕量杂质元素进行了测试,并对GD-MS工作参数进行了优化,部分元素与采用电感耦合等离子体质谱法(ICP-MS)定量分析的结果进行比较,对某些元素含量差别较大的原因进行了分析,论述了Element GD辉光放电质谱仪的特点及其在痕量杂质分析上的优势。     

碱金属原子与W,Pt表面的电荷交换

本工作利用热能碱金属原子与炽热W,Pt表面的相互作用,研究了碱金属原子与金属表面的电荷交换,以及金属表面吸附原子后表面功函数的变化。 关键词：     

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设{X,Xn;n≥1}为吸引域为正态吸引域的独立同分布的随机变量序列,本文证明了其自正则部分和的完全矩的精确渐近性.     

无界问题无网格方法和自然边界元的耦合计算

为充分利用无网格方法和自然边界元的优点,用无网格和自然边界元耦合的方法来解决带方孔的无界平面弹性问题,通过引入人工边界,用自然边界元方法来描述无界问题,编制无网格和自然边界元耦合方法的相应计算程序。与有限元方法计算结果的比较,表明了耦合方法的有效性。     

ZTS晶体生长及其非线性光学性质研究

利用水溶液缓慢降温法生长了ZTS晶体,最大尺寸达28×16×14mm3;通过X射线粉末衍射实验,得到了晶体的晶胞参数和空间群;通过粉末倍频实验测定了晶体的非线性光学性质,并与KDP晶体的粉末倍频强度对比, 结果表明ZTS晶体是一种优良的、能够实现相位匹配的非线性光学晶体;用紫外.可见光谱仪测量了晶体的透过光谱,在350～1400mm波长范围内透过率超过80;.     

Surface Structure of Large Synthetic Diamonds by High Temperature and High Pressure

With NiMnCo and FeCoNi alloys as solvent metals, large single-crystal diamonds of about 3mm across are grown by temperature gradient method （TGM） under high temperature and high pressure （HPHT）. Although both {100} and {111} surfaces are developed by a layer growth mechanism, some different characteristic patterns are seen clearly on the different surfaces, no matter whether NiMnCo or FeCoNi alloys are taken as the solvent metals. For {100} surface, it seems to have been melted or etched greatly, no dendritic patterns to be found, and only a large number of growth hillocks are dispersed net-likely; while for {111} surface, it often seems to be more smooth-faced, no etched or melted traces are present even when a lot of depressed trigonal growth layers. This distinct difference between {111} and {100} surfaces is considered to be related to the difference of surface-atom distribution of different surfaces, and {111} surfaces should be more difficult to be etched and more steady than {100} surfaces.     

旋流非预混燃烧火焰流动特性的实验研究

利用粒子图像速度场测量技术(PIV)对不同工况下的旋流非预混燃烧流场进行了测量,考察不同燃空速度比下旋流火焰的流动特性.结果表明,轴向截面上径向平均速度流场以燃烧器轴线呈中心对称,轴向平均速度、轴向脉动速度和径向脉动速度沿燃烧器轴线成对称分布,且轴向平均速度和轴向脉动速度的最大值出现在轴线处.随燃空速度比的增大,轴向平均速度和脉动速度增大,随着与燃烧器表面的距离增加,流场截面上轴向平均速度和脉动速度差异不断减小.     

头孢他啶与牛血清白蛋白(BSA)的相互作用

采用荧光、紫外及红外光谱法研究了头孢他啶与牛血清白蛋白(BSA)的结合反应.头孢他啶对BSA的色氨酸残基和酪氨酸残基均具有猝灭作用,其猝灭机理为静态猝灭,两者之间形成新的复合物是导致BSA荧光猝灭的主要原因.获取了复合物的结合常数(298K:1.27×10~4L·mol~(-1);310K:1.33×10~41·mol~(-1)).BSA Ⅱ A结构域的site I位点是其唯一可能结合位点.同步荧光光谱表明头孢他啶造成BSA的酪氨酸残基的极性增强.红外光谱表明头孢他啶引起了BSA二级结构的改变,使其α-螺旋含量降低.     

Thermal Stability and Humidity Resistance of ScTaO4 Modified （K0.5Na0.5）NbO3 Ceramics

Lead-free （Na0.5K0.5）NbO3-xmol% ScTaO4 （x=0-1.5） ceramics are prepared using the conventional solid-state reaction method and their properties are investigated in detail. The results indicate that the piezoelectric properties and density are improved by the introduction of ScTaO4. Due to the high orthorhombic-tetragonal phase transition temperature TO-T （around 200°C）, stable piezoelectric properties against temperature are obtained. In a wide temperature range of 15-160°C, kp of the （Na0.5K0.5）NbO3-0.5mol% ScTaO4 ceramic remains almost unchanged and d31 increases slightly from 59pC/N to 71pC/N. The deliquescent problem is effectively solved by the addition of ScTaO4. The piezoelectric properties of ScTaO4 modified （Na0.5K0.5）NbO3 ceramics show no obvious reduction and dielectric loss increases slightly after 120h of immersion. From the analysis, it is suggested that the density is an important factor that improves the humidity resistance of the specimens.     

三维弹性管的涡致振动特性分析

采用有限体积法联合大涡模拟方法求解三维湍流流场,采用有限元法离散弹性管结构,对Re=1.35×104的湍流流动作用下三维弹性管的涡致振动进行了数值模拟,结构的动力学响应用Newmark算法来求解,管的运动采用基于扩散光顺方法的动网格模型来实现.利用建立的数值模型,分析了升力系数、阻力系数、位移、涡脱频率、相位差随频率比的变化特征,成功扑捉到锁定、相位开关,并联合运动轨迹、相图及Poincaré截面映射,研究了升力系数与横向位移的极限环与分叉等非线性特性.研究结果表明,在阻力系数的最小值处,横向振幅达到最大值,同时,横向响应的"锁定"也始于阻力系数最小值处;在"锁定"范围内,横向振幅随着频率比的增大而逐渐减小;在升力系数的最小值处,升力系数与位移间的相位由反相变为同相;在均匀湍流流动作用下,三维弹性管的升力与横向位移并未出现周期解的分叉.