A block SPP algorithm for multidimensional tridiagonal equations with optimal message vector length

A parallel strategy for solving multidimensional tridiagonal equations is investigated in this paper. We present in detail an improved version of single parallel partition (SPP) algorithm in conjunction with message vectorization, which aggregates several communication messages into one to reduce the communication cost. We show the resulting block SPP can achieve good speedup for a wide range of message vector length (MVL), especially when the number of grid points in the divided direction is large. Instead of only using the largest possible MVL, we adopt numerical tests and modeling analysis to determine an optimal MVL so that significant improvement in speedup can be obtained.

Constitutive plasma membrane targeting and microdomain localization of Dok5 studied by single-molecule microscopy

In the present study, single-molecule fluorescence microscopy was used to examine the characteristics of plasma membrane targeting and microdomain localization of enhanced yellow fluorescent protein (eYFP)-tagged wild-type Dok5 and its variants in living Chinese hamster ovary (CHO) cells. We found that Dok5 can target constitutively to the plasma membrane, and the PH domain is essential for this process. Furthermore, single-molecule trajectories analysis revealed that Dok5 can constitutively partition into microdomain on the plasma membrane. Finally, the potential mechanism of microdomain localization of Dok5 was discussed. This study provided insights into the characteristics of plasma membrane targeting and microdomain localization of Dok5 in living CHO cells. (C) 2008 Elsevier B.V. All rights reserved.

A phylogeny of Chinese species in the genus Phrynocephalus (Agamidae) inferred from mitochondrial DNA sequences

We investigated the phylogenetic relationships among most Chinese species of lizards in the genus Phrynocephalus (118 individuals, collected from 56 populations of 14 well-defined species and several unidentified specimens) using four mitochondrial gene fragments (12S rRNA, 16S rRNA, cytochrome b, and ND4-tRNA(LEU)). The partition-homogeneity tests indicated that the combined dataset was homogeneous, and maximum-parsimony (MP), neighbor-joining (NJ), maximum-likelihood (ML) and Bayesian (BI) analyses were performed on this combined dataset (49 haplotypes including outgroups for 2058 bp in total). The maximum-parsimony analysis resulted in 24 equally parsimonious trees, and their strict consensus tree shows that there are two major clades representing the Chinese Phrynocephalus species: the viviparous group (Clade A) and the oviparous group (Clade B). The trees derived from Bayesian, ML. and NJ analyses were topologically identical to the MP analysis except for the position of P. mystaceus. All analyses left the nodes for the oviparous group, the most basal clade within the oviparous group, and P. mystaceus unresolved. The phylogenies further suggest that the monophyly of the viviparous species may have resulted from vicariance, while recent dispersal may have been important in generating the pattern of variation among the oviparous species. (C) 2003 Elsevier Science (USA). All rights reserved.

Population differentiation of Procypris rabaudi (Tchang) in the upper reaches of the Yangtze River revealed by mitochondrial DNA and RAPD markers

Procypris rabaudi (Tchang) is a cyprinid fish endermic to middle and upper reaches of the Yangtze River. Besides in main stream and large tributaries, there exists an early matured, small-sized ecological type in a small tributary, Tang River. In this study, mitochondrial DNA cytochrome h (cyt b) gene sequence analysis and randomly amplified polymorphic DNA (RAPD) analysis were performed to investigate the differentiation of the Tang River population from the Mudong reach population of the Yangtze River, with the purpose of conservation and exploitation of this fish. In the 1140 bps of cyt b gene sequence surveyed, 20 sites were found polymorphic, which defined 23 haplotypes. Among them, four haplotypes accounted for 54.4% of all individuals, while population-specific haplotypes occurred in low frequencies. Analysis of molecular variation on cyt b data revealed no significant partition existing between Tang River population and Mudong reach population. Analyses of 132 RAPD loci suggested that genetic variation between populations was significant, though values of different F-ST were not very high. The results revealed low genetic diversity and the beginning of population differentiation, suggesting that Tang River population should be designated as a separate Management Unit.

Water solubility enhancement of phthalates by cetyltrimethylammonium bromide and beta-cyclodextrin

Water solubility enhancements of six phthalates (five aliphatic phthalates and one phenyl phthalate) by cetyltrimethylammonium bromide (CTAB) and beta-cyclodextrin (beta-CD) were studied at 25 degreesC. The solubilities of these plithalates are remarkably enhanced by CTAB solutions above the critical micelle concentration (cmc). Only marginal enhancement of phthalate solubility was observed in solutions containing CTAB below its cmc and beta-CD at low concentrations (less than 5 mM). The solubility enhancements of the plithalates are proportional to the added amount of CTAB and beta-CD. Partition coefficients of the plithalates between monomeric CTAB surfactant and water (K-MN) and between CTAB micelle and water K-MC) were estimated from the experimental data. The mechanisms of solubility enhancements by CTAB and beta-CD were discussed. A log-linear equation was proposed and evaluated for the solubilization by CTAB below cmc, while the previously proposed linear partitioning model was questioned. The structures of the complexes formed between plithalates and beta-CD were proposed, and the formation constants were estimated. The values of log K-MC, log K-MN, and log Kbeta-CD of the plithalates were found to correlate linearly with the log K-OW of plithalates, with the exception of the solid phenyl phthalate.

Mn-AlInN: a new diluted magnetic semiconductor

Mn ions have been incorporated into MOCVD grown Al1-x In (x) N/GaN thin films by ion implantation to achieve the room temperature ferromagnetism in the samples. Magnetic characterizations revealed the presence of two ferromagnetic transitions one has Curie points at similar to 260 K and the other above room temperature. In-diffusion of indium caused by the Mn implantation leads to the partition of AlInN epilayer into two diluted magnetic semiconductor sub-layers depending on the Mn concentration. The Curie temperature of 260 K is assigned to the layer having lower concentration, whereas T (c) above room temperature is assumed to be associated to the layer having higher Mn concentration.

Quantum mechanical simulation of nanosized metal-oxide-semiconductor field-effect transistor using empirical pseudopotentials: A comparison for charge density occupation methods

The atomistic pseudopotential quantum mechanical calculations are used to study the transport in million atom nanosized metal-oxide-semiconductor field-effect transistors. In the charge self-consistent calculation, the quantum mechanical eigenstates of closed systems instead of scattering states of open systems are calculated. The question of how to use these eigenstates to simulate a nonequilibrium system, and how to calculate the electric currents, is addressed. Two methods to occupy the electron eigenstates to yield the charge density in a nonequilibrium condition are tested and compared. One is a partition method and another is a quasi-Fermi level method. Two methods are also used to evaluate the current: one uses the ballistic and tunneling current approximation, another uses the drift-diffusion method. (C) 2009 American Institute of Physics. [doi:10.1063/1.3248262]

Landauer-Buttiker formula for time-dependent transport through resonant-tunneling structures: A nonequilibrium Green's function approach

A nonequilibrium Green's-function formalism is employed to study the time-dependent transport through resonant-tunneling structures. With this formalism, we derive a time-dependent Landauer-Buttiker formula that guarantees current conservation and gauge invariance. Furthermore, we apply the formula to calculate the response behaviors of the resonant-tunneling structures in the presence of rectangular-pulse and harmonic-modulation fields. The results show that the displacement current plays the role of retarding the tunneling current.

高速缓存优化的并行连接算法

由于嵌套循环连接操作过程中存在较大的高速缓存缺失,严重影响了连接查询的性能。提出了一种基于缓冲的高速缓存参数无关的嵌套循环并行连接算法。通过高速缓存参数无关和缓冲技术,提高了连接算法的空间局部性和时间局部性。理论分析和实验结果表明,高速缓存优化后的串行连接算法的性能是原来的2倍,其并行算法效果近似线性加速比。

Study on the kinetics of hydrate formation in a bubble column

Gas hydrate formation experiments were performed using methane in the presence of tetrahydrofuran (THF) in aqueous solution in a transparent bubble column in which a single pipe or a sintered plate was used to produce bubbles. The mole fraction of THF in aqueous solution was fixed at 6%. The hydrate formation kinetic behaviors on the surface of the rising bubble, the mechanical stability of hydrate shell formed on the surface of the bubble, the interactions among the bubbles with hydrate shell were observed and investigated morphologically. The rise velocities of individual bubbles with hydrate shells of different thickness and the consumption rates of methane gas were measured. A kinetic model was developed to correlate the experimentally measured gas consumption rate data. It was found that the hydrate formation rate on the surface of the moving bubble was high, but the formed hydrate shell was not very easy to be broken up. The bubbles with hydrate shells tended to agglomerate rather than merge into bigger bubble. This kind of characteristic of hydrate shell hindered the further formation of hydrate and led to the lower consumption rate of methane. The consumption rate of methane was found to increase with the decrease of temperature or increase of pressure. The increase of gas flux led to a linear increase in consumption rate of methane. It was demonstrated that the developed kinetic model could be used to correlate the consumption rate satisfyingly.

生物活性有机锗及HPCPC双水相分离生物大分子的研究

本论文内容主要分为4个部分：“有机锗化合物抑制Maillard反应的研究”、“Ge-132对体外培养幼鼠胰岛细胞的作用研究”、“PEG／磷酸盐双水相体系中生物大分子分配的研究”和“HPCPC（High Performance Centrifugal Partition Chromatography，高效离心分配色谱）双水相体系对生物大分子分离的研究”。前两部分主要从有机锗化合物防治糖尿病及其并发症的代谢机理和细胞学角度进行研究，本文引入HPCPC和双水相体系分离生物大分子的技术，为进一步阐明有机锗化合物在Maillard反应过程中的作用机理：对双水相体系中生物大分子的分配及HPCPC在双水相体系中分离生物大分子也做了大量的基础性研究，为开发HPCPC的应用作出了有价值的探索工作。本论文的主要创新点归纳如下：一、有机锗化合物对Maillard反应的抑制作用：针对国际上有机锗发展的前沿课题，在国内首先开展了有机锗化合物对Maillard反应抑制作用的研究，取得了有价值的研究结果。1、在模拟体内的生理条件下，研究了不同浓度Ge-132对精氨酸、组氨酸、甘氨酸和缬氨酸对Maillard反应荧光峰强度的影响：不同类型的氨基酸Maillard反应产物结构上的差异和不同浓度有机锗对组氨酸糖化反应420nm处特征吸光度的影响。2、苯丙氨酸是侧链带有苯环的芳香族氨基酸，是一种具有弱的天然荧光的生物小分子，其荧光最大发射位置在281.6nm。由于aillard反应是葡萄糖和氨基酸的-NHR基发生的反应，其反应产物的特征荧光在440nm附近。这两类荧光的发射位置相差较远，相互之间没有影响，因此利用荧光法观察Phe在反应过程中自身的荧光变化和Ge-132对Phe的Maillard反应荧光产物的抑制情况。3、血清白蛋白是哺乳动物体内的重要蛋白质，可作为多种内源性、外源性物质的存储和转运蛋白，其Maillard反应已经被广泛重视，但较复杂的实验条件限制了它的研究。通过观测蛋白质Maillard反应产物特征荧光的变化是一有效的研究方法。BSA的内源性荧光是由肽链色氨酸和酪氨酸残基贡献的，其最大发射位置340nm左右。其Maillard反应产物的特征荧光在440nm附近，这两类荧光发射位置相差较远，基本上没有影响，因此能够通过荧光光谱研究BSA的Maillard反应荧光产物的情况。本文观测了Ge-132对BSA的Maillard反应荧光产物的抑制作用，同时还通过荧光法确定了一个文献中没有的新的反应位点。4、本文研究了具有更高水溶性的一类双有机锗化合物(HO)_2Ge(CHR_1CHR_2COOH)_2．2H_20抑制Maillard反应的特性，结果证明它比Ge-132具有更高的抑制作用，我们通过化合物的构效关系解释了上述作用的机制。5、本文研究了Tb(Ge-132)_3和Eu(Ge-132)_3两种含稀土的配合物对氨基酸、蛋白质Maillard反应的影响，观察了稀土离子对Maillard反应体系的影响，对实验现象作出了合理的解释。二、Ge-132对体外培养幼鼠胰岛细胞的作用为进一步考察有机锗对糖尿病的防治作用，我们与白求恩医大合作，首次观察了Ge-132对体外培养的幼鼠胰岛细胞结构和功能的影响，研究了不同剂量的含锗化合物对幼鼠胰岛细胞分泌胰岛素的作用，认为低浓度的Ge-132对胰岛细胞分泌胰岛素具有明显的促进作用。该部分内容为首次报导。三、PEG／磷酸盐双水相体系中生物大分子分配的研究双水相萃取TPE(Aqueous Two-Phase Extraction)具有下述优点：生物相容性好、界面张力低、能量低、易于工业规模的放大、可以进行连续操作等。本论文系统地研究了各种蛋白质在PEG／磷酸盐体系中的分离情况，如在各种pH条件下，从6.8到9.2，各种分子量的PEG，包括PEGl000，2000，5000，6000，10000，和20000和磷酸盐双水相体系的物化性质，以及对lysozyme（溶菌酶），BSA（牛血清白蛋白），HSA（人血清白蛋白），Hemoglobin（血红蛋白）在各种体系中的分配系数，探讨了各种因素对生物大分子分配的影响。四、HPCPC在双水相体系对生物大分子分离的研究由于荧光光谱法证实了Ge-132对牛血清白蛋白Maillard反应的抑制作用。但对于如何能够分离出糖化产物，达到进行定量表征的目的是我们研究的一个重要内容。九十年代初，由日本研制出一种色谱中新技术HPCPC。HPCPC与传统的液相色谱(LC)和高效液相色谱(HPLC)不同，不需要固体作为支持体。流动相和固定相分别为两种不相混溶的液体，通过离心力的作用使其中一相作为固定相保持在类似多级萃取器的微小分配槽中，另一相作为流动相流经固定相。HPCPC在双水相体系的应用是一种利用多级连续萃取从双水相中分离生物物质的方法它具有运行时间快、高效高选择性，流动相与固定相之间比例可以任意改变，并在任何pH值均可进行正向和反向操作并且实验室规模可一步直接放大到生产规模。它不仅可以作为一种分离的工具，而且也是一种研究生物萃取反应动力学机理，反映热力学与动力学之间相关性的重要方法。本论文中研究了常用的两种双水相体系，利用PEG6000／Dex20000／H_20对BSA和Maillard反应产生的糖化BSA进行了初步分离，取得了一些阶段性结论。另外，通过对各种条件的筛选，选择了具有代表性的lysozyme和BSA，BSA和血红蛋白(Hb)进行HPCPC色谱仪上的分离，研究了色谱分离条件如：转数、流速、pH等对分离效率及理论塔板数的影响，取得了一系列重要的结论。为工业上大规模的生物样品分离提供了重要的参数。

CALCULATION OF SPIN-REORIENTATION TEMPERATURE IN ND2FE14B

The spin-reorientation phenomenon in Nd2Fe14B has been investigated using an angular dependent free energy approach. A magnetic Hamiltonian which includes the crystal electric field term and the exchange term has been established using realistic band structure results. The temperature dependence of the molecular field is accounted for by introducing the Brillouin function and the magnetic Hamiltonian is diagonalized within the ground state multiplet of the Nd ion. The eigenstates are then used to form the partition function for the free energy. At each temperature, the direction of the molecular field is obtained by searching for the minimum in the angular parameter space of the free energy. Our calculations show that for Nd2Fe14B, the net magnetic anisotropy direction is canted away from the c axis at a temperature close to the experimentally reported spin-reorientation temperature of 150 K. The temperature dependence of the magnetic structure is found to be very sensitive to the size of the second order crystal field parameter B20.

一类0-1背包问题算法程序的形式化推导

0-1背包问题是经典的组合优化问题与NP完全问题,具有重要的应用价值与理论意义.本文使用PAR(Partition and Recurrence)方法形式化推导了0-1背包问题的高效动态规划算法程序.通过类比分析,该问题的若干变形问题的算法也可推导得到,算法通过PAR平台的自动生成系统转换成可执行语言程序并运行通过,保证了该类0-1背包问题算法的正确性和可靠性.本文主要的贡献是将PAR方法推广到能处理带约束条件的组合优化类问题,大大扩展了PAR方法的应用范围,为形式化开发高效高可信组合优化类算法开辟了一条新途径.

辽东次生林土壤呼吸及主要组分分离与量化

土壤呼吸是森林生态系统碳循环的重要组成部分，对土壤呼吸的主要组分根系呼吸和土壤微生物呼吸进行分离并量化，对于了解土壤碳释放规律、估算生态系统土壤碳的年际通量以及预测气候变化条件下根系或土壤微生物对土壤碳释放格局的影响具有重要意义。本文采用挖壕法测定辽东山区蒙古栎林、杂木林和胡桃楸林的土壤表面CO2通量，并同步分析土壤水热因子及土壤有机质、N含量、根系生物量、土壤酶活性、土壤微生物生物量等。研究结果表明：（1）辽东山区次生林0-10cm土壤有机质含量为9.29-18.15%，全氮含量为0.43-0.90%，pH值为5.67-6.19；次生林生长季细根生物量平均为152.61- 447.79 g/m2，粗根生物量平均为255.42-507.42 g/m2，根系总量平均为540.93-955.22 g/m2；土壤酶活性季节变化明显，且具垂直分布特征，蒙古栎林的土壤转化酶、淀粉酶和脱氢酶活性最高，胡桃楸林最低，胡桃楸林过氧化氢酶活性相对最大；土壤微生物量碳、氮的季节变化呈明显的单峰曲线并与土壤温度相关，土壤微生物量碳氮之间具显著相关性（P<0.05）。（2）次生林土壤总呼吸、根呼吸和土壤微生物呼吸具明显的日、季变化规律，生长季根呼吸贡献相对较低，胡桃楸林根呼吸贡献率为34.0-34.8%，蒙古栎林为17.9-28.4%，杂木林为14.7-35.3%；土壤微生物呼吸贡献率为66.0-85.3%，高于根呼吸贡献率，说明辽东山区次生林土壤微生物呼吸决定土壤总呼吸的变化趋势。（3）土壤呼吸与地下5cm土壤温度呈指数函数关系，土壤总呼吸的Q10值为1.29-2.30，微生物呼吸的Q10值为1.28-2.09，根呼吸的Q10值为1.29-3.72；土壤总呼吸、微生物呼吸、根呼吸与土壤含水量均无明显相关关系；蒙古栎林根呼吸与细根生物量显著相关，杂木林根呼吸与粗根生物量及根系总生物量显著相关，胡桃楸林根呼吸与根系生物量总量显著相关（P<0.05）；微生物呼吸与淀粉酶、转化酶、脱氢酶、过氧化氢酶均无显著相关性（除胡桃楸林与过氧化氢酶显著相关）；微生物呼吸与土壤微生物量碳、氮均呈显著线性相关关系（P<0.05）。（4）蒙古栎林土壤总呼吸、根呼吸、土壤微生物呼吸年际碳释放量分别为572.78、147.78和425.59 g C m-2a-1，杂木林分别为403.12、108.92、297.51 g C m-2a-1，胡桃楸林分别为519.47、173.75、345.72 g C m-2a-1；生长季和非生长季通过根呼吸释放的碳量均小于分解土壤有机质的微生物呼吸释放的碳量，非生长季次生林土壤碳释放量为39.21-152.04 g C m-2a-1，占全年呼吸总量的10-29%，说明冬季土壤碳释放量不能忽略。