分布式系统中进程迁移算法研究

进程迁移是改善分布式系统的负载平衡和稳定性的一种有效手段,本文总结了主要的４ 类进程迁移算法,比较了它们的优点和缺点．并将该算法与“中庸算法”相结合,为“中庸算法”的实现打下了理论基础．     

蚕豆(Vicia faba L.)对不同水分胁迫的光合适应性研究

以重庆市的蚕豆当家品种之一的大白豆为材料,通过人工水分胁迫处理,发现随干旱程度的增加,蚕豆叶片的叶绿素a、叶绿素b含量和叶绿素总降低,Hill反应活力下降,净光合速率下降,同化产物的积累减少,最终表现为植株生物量的降低,水分胁迫下植株净光合速率下降,光饱和点降低,光补偿点提高,CO2补偿点提高,光呼吸增大,生长减弱,这时导致生物量积累减少的主要原因。     

Rapid quantification of levosulpiride in human plasma using RP‐HPLC‐MS/MS for pharmacokinetic and bioequivalence study

A rapid and validated method for analysis of levosulpiride in human plasma using liquid chromatography coupled to tandem mass spectrometry was developed. Levosulpiride and tiapride (IS, internal standard) were extracted from alkalized plasma samples with ethylacetate and separation by RP‐HPLC. Detection was performed by positive ion electrospray ionization in multiple‐reaction monitoring mode, monitoring the transitions m/z 342.1 → m/z 112.2 and m/z 329.1 → m/z 213.2, for quantification of levosulpiride and IS, respectively. The standard calibration curves showed good linearity within the range of 2–200 ng/mL (r² ≥ 0.9990). The lower limit of quantitation was 2 ng/mL. The retention times of levosulpiride (0.63 min) and IS (0.66 min) presented a significant time saving benefit of the proposed method. No significant metabolic compounds were found to interfere with the analysis. This method offered good precision and accuracy and was successfully applied for the pharmacokinetic and bioequivalence study of a 25 mg of levosulpiride tablet in 24 healthy Korean volunteers. Copyright © 2009 John Wiley & Sons, Ltd.     

Holographic quantitative structure-activity relationship for prediction of the toxicity of polybrominated diphenyl ether congeners

Polybrominated diphenyl ether congeners (PBDEs) might activate the AhR (aromatic hydrocarbon receptor) signal transduction, and thus might have an adverse effect on the health of humans and wildlife. Because of the limited experimental data, it is important and necessary to develop structure-based models for prediction of the toxicity of the compounds. In this study, a new molecular structure representation, molecular hologram, was employed to investigate the quantitative relationship between toxicity and molecular structures for 18 PBDEs. The model with the significant correlation and robustness (r ² = 0.991, q ² _LOO = 0.917) was developed. To verify the robustness and prediction capacity of the derived model, 14 PBDEs were randomly selected from the database as the training set, while the rest were used as the test set. The results generated under the same modeling conditions as the optimal model are as follows: r ² = 0.988, q ² _LOO = 0.598, r ² _pred = 0.955, and RMSE (root-mean-square of errors) = 0.155, suggesting the excellent ability of the derived model to predict the toxicity of PBDEs. Furthermore, the structural features and molecular mechanism related to the toxicity of PBDEs were explored using HQSAR color coding.     

Synthesis and characterization of α-N,N-dihydroxyethylaminopropyl-ω-butylpolydimethylsiloxanes

A series of α-N,N-dihydroxyethylaminopropyl-ω-butylpolydimethylsiloxanes with different molecular weight were synthe-sized. The preparation included five steps which were hydroxyl protection, alkylation, anionic ring-opening polymerization,hydrosilylation and deprotection. The structure of reaction products was characterized by FF-IR, GC, 1H NMR.     

79Br NMR spectroscopy as a practical tool for kinetic analysis

⁷⁹Br NMR spectroscopy has been used to monitor a series of reactions in which the bromide ion is produced, including the Menschutkin reaction of pyridine with a range of substituted benzyl bromides and a Heck coupling process. In cases where the process could also be monitored using ¹H NMR spectroscopy, the kinetic analyses using heteronuclear magnetic resonance spectroscopy were shown to be completely consistent. Both the utility of the process in following reactions which may be difficult to analyse using other techniques and the practical limitations associated with solvent choice are discussed. Copyright © 2009 John Wiley & Sons, Ltd.     

基于反饱和吸收和自聚焦两种效应的光限幅器

用酞菁铜金属有机染料首次演示了基于反饱和吸收和自聚焦两种效应的光限幅器．实验和理论分析表明，这种限幅器的输入阈值功率由反饱和吸收决定，而自聚焦使限幅器的最大限幅输出功率降低，限幅效果显著增强．     

组合荷载作用下拦污栅栅条稳定性计算通式

根据栏污栅的控制工况，指出栅条倾覆稳定的计算简图为集中力与均布荷载同时作用的双悬臂简支梁，应用瑞利商求解其倾覆稳定微分方程，给出了组合荷载作用时栅条稳定临界荷载计算方法，通过对比分析表明了本文方法的合理性，最后还介绍了该方法的工程应用，可供生产设计及修订规范参考。     

Observation of triangle pits in PbSe grown by molecular beam epitaxy

PbSe thin films on BaF₂ (1 1 1) were grown by molecular beam epitaxy with different selenium beam flux. Evolution of PbSe surface morphologies with Se/PbSe beam flux ratio (R_f) has been studied by atomic force microscopy and high-resolution X-ray diffraction. Growth spirals with monolayer steps on PbSe surface are obtained using high beam flux ratio, R_f ≥ 0.6. As R_f decreases to 0.3, nano-scale triangle pits are formed on the surface and the surface of PbSe film changes to 3D islands when R_f = 0. Glide of threading dislocations in 〈1 1 0〉{1 0 0}-glide system and Pb-rich atom agglomerations are the formation mechanism of spiral steps and triangle pits. The nano-scale triangle pits formed on PbSe surface may render potential applications in nano technology.     

Molecular beam epitaxy of CdSe epilayers and quantum wells on ZnTe substrate

We have grown zinc-blende cadmium selenide (CdSe) epilayers on ZnTe-(0 0 1) substrate by molecular beam epitaxy (MBE). By controlling the substrate temperature and beam-equivalent pressure (BEP) ratio, of Se to Cd, we determined the most suitable growth condition based on reflection high-energy electron diffraction (RHEED) pattern. At a substrate temperature of 280 °C and a BEP ratio of 3.6, the RHEED pattern showed a V-like feature, indicating a rough surface with facets. As the substrate temperature was increased to 360 °C at the same BEP ratio, a V-like RHEED pattern moved to a clear streaky pattern. Moreover when the BEP ratio was increased to 4.8 at 360 °C of substrate temperature, a clear (2 × 1) reconstruction of the CdSe layer was observed. A CdSe/CdMgSe single quantum well structure was also grown on ZnTe-(0 0 1) substrate by MBE. The RHEED pattern showed a clear (2 × 1) surface reconstruction during the growth. By photoluminescence measurement, a good optical property of the structure was obtained.