Variational Approach to the Thomas-Fermi Equation

By the semi-inverse method, a variational principle is obtained for the Thomas-Fermi equation, then the Ritz method is applied to solve an analytical solution, which is a much simpler and more efficient method.

Characterization Of Crystal Structure In Binary Mixtures Of Latex Globules

Colloidal crystals formed by two types of polystyrene particles of different sizes (94 and 141 nm) at various number ratios (94:141 nm) are studied. Experiments showed that the formation time of crystals lengthens as the number ratio of the two components approaches 1:1. The dependence of the mean interparticle distance (D-0), crystal structure and alloy structure on the number ratio of the two types of particles was Studied by means of Kossel diffraction technique and reflection spectra. The results showed that as the number ratio decreased, the mean interparticle distance (D-0) became larger. And the colloidal crystal in binary mixtures is more preferably to form the bcc structure. This study found that binary systems form the substitutional solid solution (sss)-type alloy structure in all cases except when the number ratio of two types of particles is 5:1, which results instead in the superlattice structure. (C) 2008 Elsevier Inc. All rights reserved.

Stimulated Raman adiabatic passage from atomic to molecular Bose-Einstein condensates: Feedback laser-detuning control and suppression of dynamical instability

We present a feedback control scheme that designs time-dependent laser-detuning frequency to suppress possible dynamical instability in coupled free-quasibound-bound atom-molecule condensate systems. The proposed adaptive frequency chirp with feedback is shown to be highly robust and very efficient in the passage from an atomic to a stable molecular Bose-Einstein condensate.

Energy spectrum of two-component Bose-Einstein condensates in optical lattices

With the method of Green's function, we investigate the energy spectra of two-component ultracold bosonic atoms in optical lattices. We End that there are two energy bands for each component. The critical condition of the superfluid-Mott insulator phase transition is determined by the energy band structure. We also find that the nearest neighboring and on-site interactions fail to change the structure of energy bands, but shift the energy bands only. According to the conditions of the phase transitions, three stable superfluid and Mott insulating phases can be found by adjusting the experiment parameters. We also discuss the possibility of observing these new phases and their transitions in further experiments.

A single-layer magnetic atom chip for trapping an array of Bose-Einstein condensate

We propose a simple single-layer magnetic microtrap configuration which can trap an array of magnetically-trapped Bose-Einstein condensate. The configuration consists of two series of parallel wires perpendicular to each other and all of the crossing points are cut off for maintaining the uniformity of the current. We analyse the trapping potential, the position of trapping centres and the uniformity of the array of the traps. The trapping depth and trapping frequency with different parameters are also calculated. Lastly, the effect of the cut-off crossing points, dissipate power, chip production are introduced concisely.

Coherent scattering of light by Bose-Einstein condensation in a tight confinement

We have observed strong scattering of a probe light by dilute Bose-Einstein condensate (BEC) Rb-87 gas in a tight magnetic trap. The scattering light forms fringes at the image plane. It is found that we can infer the real size of the condensation and the number of the atoms by modelling the imaging system. We present a quantitative calculation of light scattering by the condensed atoms. The calculation shows that the experimental results agree well with the prediction of the generalized diffraction theory, and thus we can directly observe the phase transition of BEC in a tight trap.

牛耳草Bose hygrometrica 离体叶脱水-复水过程的光合作用及基因表达

本文以复苏植物牛耳草Boea hygrometrica成熟植株的离体叶片为试材，对比非复苏植物烟叶唇苣苔Chirita heterotricha, 以光合作用在脱水－复水过程中的变化为切入点，从生理水平上探讨其脱水保护位点：应用mRNA差异显示技术，从分子水平上探讨其脱水保护机制。 光合放氧速率、快速荧光诱导动力学、慢速荧光诱导动力学、荧光发射光谱、荧光激发谱的结果表明，相对于烟叶唇柱苣苔，脱水对牛耳草净光合速率、PS II和PS I光化学活性、电子传递、光合磷酸化及CO_2固定的影响有一个共同的特点，即脱水时迅速降低，复水后恢复能力强。通过非变性绿胶的研究牛耳草叶片类囊体膜叶绿素－蛋白复合体在脱水－复水过程中保持高度稳定。色素含量分析表明牛耳草的叶绿素含量在脱水－复水过程中也相对稳定。这些特征可能是牛耳草叶片光合作用脱水保护机制的一部分。 SDS－PAGE和IEF电泳结果表明，牛耳草脱水复苏过程中蛋白质表达有差异，或增或减，并分别发现了一条（SDS－PAGE）和两条（IEF）在脱水过程中特异出现的蛋白质。 本文以银染法代替放射自显影用于mRNA差异显示，不但简化了实验步骤，缩短了实验周期，而且在不降低灵敏度的前提下避免了放射性危害，降低了实验成本。本文证明了mRNA差异银染显示法用于复苏植物牛耳草脱水－复水过程中基因表达变化的研究是可行的。 mRNA差异银染显示法揭示牛耳草耐脱水复苏机制涉及到基因表达的调控。脱水－复水过程中差异表达的基因有6种，其中脱水特异诱导表达的13个cDNA所相应的基因、脱水上调节的15个cDNA所相应的基因可能参与牛耳草叶片脱水保护机制，复水特异诱导的8个cDNA的所相应基因可能参与牛耳草复水后的修复机制。2个脱水特异诱导表达的cDNA片段进行了克隆和测序。