勾形磁场对分离结晶法制备CdZnTe晶体的影响

为了了解勾形磁场对CdZnTe晶体生长质量的影响,利用有限元法对坩埚内的热量和动量传递过程进行了全局数值模拟。假定熔体和气相中的流动都为准稳态轴对称层流,研究了B_o(磁场轴线与晶体-坩埚界面的交点的磁场强度的轴向分量)为0 T,0.5 T,1.0 T,1.5 T,2.0 T,2.5 T,3.0 T时的CdZnTe晶体生长过程。结果表明:勾形磁场能有效抑制熔体内的流动,会产生由洛仑兹力、表面张力和浮力共同驱动的涡胞。随着磁场强度的增加,传热向导热型转变,熔体内最大流函数逐渐减小,抑制作用增强。     

Rotational and vibrational temperature determination by DFWM spectroscopy

Using the DFWM technique we determined rotational and vibrational temperatures of NaH molecules in a dynamical system consisting of NaH, Na, H and H₂ for several heat-pipe oven temperatures. We applied a new way to determine the dependence of the DFWM signalI _c ^int on the power of the transition dipole momentµ without previous knowledge of the temperature. The revealed dependence isI _c ^int µ ⁴. In this case the laser intensities were found to be of the same order as the saturation intensity in accordance with simple DFWM theory. A usual Boltzmann plot was employed for the determination of the relevant rotational temperatures, which displayed higher values than the oven temperature.     

Asymptotic cohomological functions of toric divisors

We study functions on the class group of a toric variety measuring the rates of growth of the cohomology groups of multiples of divisors. We show that these functions are piecewise polynomial with respect to finite polyhedral chamber decompositions. As applications, we express the self-intersection number of a T-Cartier divisor as a linear combination of the volumes of the bounded regions in the corresponding hyperplane arrangement and prove an asymptotic converse to Serre vanishing.     

高温超导薄膜生长机理初探

在3×10×0.5mm3的LaAlO3(001)基片上,利用直流磁控溅射生长一层厚度约为700nm的非晶态Tl2Ba2CaCu2Ox先驱薄膜.将先驱薄膜与热处理过的Tl2Ba2Ca2Cu3Oy块材(作为Tl源)一起在720～860℃温度下退火.为了研究薄膜的初期成核情况,退火时间一般为5分钟.利用XRD和完全抗磁性测试方法对样品的成相情况进行研究,结果显示,在薄膜生长的初期,较高的退火温度可以获得较大尺寸的初期生长核,但是退火温度达到860℃时,初期成核的晶粒尺寸变小.     

Eine Beziehung zwischen Binomialkoeffizienten und Primzahlpotenzen

Ohne Zusammenfassung     

The membrane inclusions curvature equations

We examine a system of equations arising in biophysics whose solutions are believed to represent the stable positions of N conical proteins embedded in a cell membrane. Symmetry considerations motivate two equivalent refomulations of the system which allow the complete classification of solutions for small N<13. The occurrence of regular geometric patterns in these solutions suggests considering a simpler system, which leads to the detection of solutions for larger N up to 280. We use the most recent techniques of Gröbner bases computation for solving polynomial systems of equations.     

微波消解-火焰原子吸收光谱法测定四大怀药中的Fe和Zn

探讨了测定四大怀药中微量元素铁和锌的新方法.用高压密闭微波消解-火焰原子吸收法测定四大怀药——怀山药、怀菊花、怀地黄、怀牛膝等怀药中微量元素Fe和Zn的含量.铁的回归方程为y=0.0968x+0.0114,r=0.9995(n=6),线性范围0-6.4μg/mL,平均回收率91.29％-101.06％,RSD为1.334％-4.314％.样品铁含量为159.091-1535.64μg/g.锌的回归方程为y=0.4207x+0.0039,r=0.9996(n=6),线性范围0-1.2μg/mL,平均回收率93.58％-100.85％,RSD为1.145％-3.634％.样品锌含量43.571-70.357μg/g.微波消解法消解样品,具有省时、简便、经济、消解完全、污染少等特点,可用于怀药微量元素的测定.     

Macroscopic Isotope Separation of 13C by a CO2 Laser

By photochemical dissociation of the rare carbon isotope component of CHClF₂ by means of a CO₂ laser with an average power of 150 W, Q-switched at 10 kHz, we have demonstrated the separation of more than 1 mol of ¹³C, enriched to 50% (2 mol of total carbon). It is contained in about 1 mol (101 g) of the product C₂F₄. The total throughput of the starting material was 29 kg. The experiment was run day and night for 2 weeks, almost only controlled by a computer. We obtained production rates of 5 mmol/h, corresponding to about 0.5 kg ¹³C per year.     

Infrared laser-spectroscopic analysis of <Superscript>14</Superscript>NO and <Superscript>15</Superscript>NO in human breath

We report on monitoring of nitric oxide (NO) traces in human breath via infrared cavity leak-out spectroscopy. Using a CO sideband laser near 5 μm wavelength and an optical cavity with two high-reflectivity mirrors (R=99.98%), the minimum detectable absorption is 2×10⁻¹⁰ cm⁻¹ Hz^1/2. This allows for spectroscopic analysis of rare NO isotopologues with unprecedented sensitivity. Application to simultaneous online detection of ¹⁴NO and ¹⁵NO in breath samples collected in the nasal cavity is described for the first time. We achieved a noise-equivalent detection limit of 7 parts per trillion for nasal ¹⁵NO (integration time: 70 s).