Thermal Resistance Measurement across a Wick Structure Using a Novel Thermosyphon Test Chamber

A novel system is developed for measuring the thermal resistance across thin layers of sintered copper wicks of varying porosity. Wicks to be tested are integrated into a passive vertical thermosyphon system, and the resistance is measured for a series of input power levels. The wicks are sintered to a thermally conducting pedestal above a pool of deionized water and heated from below. The apparent thermal resistance across the wick (from the pedestal/wick interface to the vapor space) under the evaporative operating conditions encountered in heat pipes is measured using thermocouples. The apparent thermal resistance across the wick is measured to be as low as 0.01°C/W, corresponding to an evaporative heat transfer coefficient of greater than 128,000 W/m²K.     

Decomposition model for phonon thermal conductivity of a monatomic lattice

An analytical treatment of decomposition of the phonon thermal conductivity of a crystal with a monatomic unit cell is developed on the basis of a two-stage decay of the heat current autocorrelation function observed in molecular dynamics simulations. It is demonstrated that the contributions from the acoustic short- and long-range phonon modes to the total phonon thermal conductivity can be presented in the form of simple kinetic formulas, consisting of products of the heat capacity and the average relaxation time of the considered phonon modes as well as the square of the average phonon velocity. On the basis of molecular dynamics calculations of the heat current autocorrelation function, this treatment allows for a self-consistent numerical evaluation of the aforementioned variables. In addition, the presented analysis allows, within the Debye approximation, for the identification of the temperature range where classical molecular dynamics simulations can be employed for the prediction of phonon thermal transport properties. As a case example, Cu is considered.     

电化学方法研究(phen)2Cu2+配合物与DNA的相互作用

用电化学循环伏安法和微分脉冲伏安法研究了1,10-邻菲咯啉铜配合物[（phen）2Cu^2＋]与小牛胸腺DNA（CTDNA）的相互作用。结果发现,在pH=7．4的三羟甲基胺基甲烷-盐酸缓冲溶液（Tris—HCl）中,（phen）2Cu^2＋配合物的铜离子在循环伏安图上呈现明显的准可逆氧化-还原波。当加入一定量的小牛胸腺DNA时,配合物（phen）,Cu^2＋的氧化和还原峰电流均有所下降。通过比较（phen）2Cu^2＋配合物中加入单链DNA和双链DNA后的氧化和还原峰电流下降的程度,前者比后者F降的程度小,可以得出（phen）2Cu^2＋配合物与小牛胸腺双链DNA的作用方式存在着插入式的沟槽结合模式。这个结论在本实验中由盐效应进一步得到证实。由此可知,（phen）2Cu^2＋配合物与小牛胸腺DNA形成了一种插入式的电惰性结合物,从而导致氧化还原峰电流下降。     

应变对纳米铜晶界迁移的影响

用分子动力学方法模拟了金属铜纳米双晶中晶界在应变作用下的迁移过程,晶界类型为〈11l〉倾侧∑19晶界。原子问相互作用力采用Finnis-Sinclair型EAM势计算。结果表明：平行于晶界方向的压应变可以促进晶界在相邻品界交互作用下发生迁移;垂直于晶界方向的压应变则不能对晶界迁移产生明显的效果。晶界迁移大致可分为两个阶段,前阶段晶界迁移缓慢,随晶界间距减小,晶界间交互作用加强,使晶界迁移显著加速。     

单颗金刚石切削无氧铜的声发射关联维特征

声发射技术可以实现无氧铜切削加工特征的监测与评价。采用声发射技术监测单颗金刚石磨粒旋转切削无氧铜,利用G-P算法重构出声发射时域信号相空间,采用自相关函数法计算出相空间时间延迟参数,通过相空间双对数曲线的计算,得到不同切削工况下的关联维数。研究结果表明,进给速度和切削速度对声发射信号影响较不显著,切深与声发射信号振幅呈正效应关系;声发射信号双对数曲线呈现阶段性增加趋势,并逐渐收敛于饱和状态,关联维数随着嵌入维数的增加先快速下降后趋于平稳;金刚石切削无氧铜的声发射信号具有混沌运动变化特性,在较小嵌入维数时,关联维数与切深和切削速度呈现线性负效应关系,与进给速度呈现线性正效应关系。该研究为无氧铜的切削加工提供理论参考。     

5,10,15,20—四(4-甲氧基-3-磺酸苯基)卟啉光度法测定痕量铜的研究

5,10,15,20-四(4-甲氧基-3-磺酸苯基)卟啉[T(4-MOP)PS_4]是一种新的水溶性卟啉显色剂.它与铜反应的最适pH=3.2,配合物的最大吸收波长为416.3um,配位比为1:1,摩尔吸光系数为 3.18×10~5 L·mol~(-1)·cm~(-1).显色后用0.10mol/LHC12.0ml酸化..该试剂具有灵剂度高选择性好的特点,无需加任何掩蔽剂可成功地用于头发和大米中痕量铜的测定,所得结果与原子吸收光度法很一致.方法的测定范围是0-3.5ugCu~(2+)/25m1.相关系数r=0.9991.     

CO2 laser welding of copper slabs

For the first time it has been possible to laser weld copper sheets up to 3 mm thick with a 2 kW cw CO₂ laser. The main questions arising from the process are indicated.     

亚硝酸钠化高铁血红蛋白的拉曼光谱量化检测研究

对亚硝酸钠化的高铁血红蛋白进行了拉曼光谱特性的研究。实验中将正常血红蛋白用亚硝酸钠氧化为高铁血红蛋白,通过测定不同比例高铁血红蛋白/总血红蛋白的拉曼光谱变化研究高铁血红蛋白的拉曼光谱特异性改变,并对不同比例高铁血红蛋白/总血红蛋白在1 586,1 605和1 637 cm-1处的拉曼强度进行线性拟合,以实现其定量检测。结果显示,亚硝酸钠与血红蛋白的摩尔比为3.5∶1时可以获得完全氧化的高铁血红蛋白,其拉曼特征峰在499,1 340,1 562,1 622 cm-1附近;不同比例高铁血红蛋白/总血红蛋白在1 586,1 605和1 637 cm-1处拉曼强度的线性拟合相关系数R2分别为0.972 84,0.997 97和0.991 26,显示出很好的线性关系。研究表明,与正常血红蛋白相比,亚硝酸钠化高铁血红蛋白的拉曼光谱具有特异性改变,其拉曼特征峰的位置和强度随着高铁血红蛋白/总血红蛋白比例的变化而相应发生改变,且比值与拉曼强度存在着线性相关关系,为临床上高铁血红蛋白血症的拉曼光谱检测与量化研究提供了理论基础。     

Ab initio study of sodium intercalation into metal oxides

Using the full-potential linearized augmented plane wave (FP-LAPW) method, we have studied the effect of chemistry on the average intercalation voltage (AIV) caused by the Na ions intercalating into transition metal oxides. The effect of transition metal was systematically studied by varying M=Co, Ni and Mn in NaMO₂ and fixing the α-NaFeO₂ layered structure. The effect of the guest atoms into the host material is discussed in terms of the structural and electronic properties. Comparatively to Li intercalation, a significant electron transfer towards transition metal was found. This observation suggests that the transition metal contribute to the AIV determination and confirms the common assumption that intercalated electron reduces M⁴⁺ to M³⁺.