RABA (Reductive Alkylation By Acetone): A novel stable isotope labeling approach for quantitative proteomics

Quantitative proteomics is challenging and various stable isotope based approaches have been developed to meet the challenge. Hereby we describe a simple, efficient, reliable, and inexpensive method named reductive alkylation by acetone (RABA) to introduce stable isotopes to peptides for quantitative analysis. The RABA method leads to alkylation of N-terminal and lysine amino groups with isopropyl moiety. Using unlabeled (d₀) and deuterium labeled (d₆) acetone, a 6 Da mass split is introduced to each isopropyl modification between the light and heavy isotope labeled peptides, which is ideally suited for quantitative analysis. The reaction specificity, stoichiometry, labeling efficiency, and linear range of the RABA method have been thoroughly evaluated in this study using standard peptides, tryptic digest of proteins, as well as human cell lysate. Reliable quantitative results have been consistently obtained in all experiments. We also applied the RABA method to quantitative analysis of proteins in spinal cords of transgenic mouse models of amyotrophic lateral sclerosis. Highly homologous proteins (transgenic human SOD1 and endogenous mouse SOD1) were distinguished and quantified using the method developed in this study. In addition, the quantitative results using the RABA approach were independently validated by Western blot.     

Global dynamics behaviors for a nonautonomous Lotka–Volterra almost periodic dispersal system with delays

A nonautonomous Lotka–Volterra dispersal system with continuous delays and discrete delays is considered. By using a comparison theorem and delay differential equation basic theory, we obtain sufficient conditions for the permanence of the population in every patch. By constructing a suitable Lyapunov functional, we prove that the system is globally asymptotically stable under some appropriate conditions. Using almost periodic functional hull theory, we get sufficient conditions for the existence, uniqueness and globally asymptotical stability for an almost periodic solution. This implies that the population in every patch exhibits stable almost periodic fluctuation. Furthermore, the results show that the permanence and global stability of system, and the existence and uniqueness of a positive almost periodic solution, depend on the delay; then we call it “profitless”.     

一类p-Laplace方程边值问题解的存在性

主要讨论一维p-Laplace方程在Neumann边值条件u(0)=0,u(1)=0下,对应的边值问题解的存在性.通过使用度理论,在适当的条件下,建立了对于p-Laplace方程在Neumann条件下解的存在性的充分条件.     

LIA组元的脉冲功率调制系统研制

本文介绍一种以加速组元为终端负载的纳秒脉冲功率系统。获得的加速间隙电压为350kV，90ns(半高宽)，波形上升时间为30ns；Blumlein主开关工作电压大于280kV，抖动小予1.5ns(均方根值)。对同轴场畸变开关性能的进一步改善作了必要的讨论，提出了用等场强原则偏置触发极，比通常采用自然中位面方法，可使开关工作电压提高8．7％。     

Determination of Synthetic Phenolic Antioxidants in Vegetable Oil and Oil-Enriched Foods by High-Performance Liquid Chromatography with Electrochemical Detection

Three synthetic phenolic antioxidants, tertiary butyl hydroquinone, butylated hydroxytoluene, and butylated hydroxyanisole, were determined in vegetable oil and oil-enriched food by high-performance liquid chromatography (HPLC) with electrochemical detection. The separation was achieved using a reverse-phase column and gradient elution with methanol and 1% acetic acid. The limits of detection and quantification of the analytes were 2–120 lower, higher than those obtained by diode-array detection. The recoveries were 103.3% for tertiary butyl hydroquinone, 97.3% for butylated hydroxyanisole, and 95.2% for butylated hydroxytoluene. The results showed that HPLC with electrochemical detection is suitable for the quantification of low concentrations of phenolic antioxidants in vegetable oil and oil-enriched food with high sensitivity and accuracy.     

随机压电智能桁架结构闭环控制概率动力响应分析

针对随机压电智能桁架结构研究了基于概率的结构闭环控制系统动力响应分析模型与方法．考虑结构的物理参数、几何尺寸、外荷载幅值以及闭环系统控制力同时具有随机性时，利用振型迭加法导出了结构动力响应随机变量的数字特征计算表达式．通过算例考察了智能结构物理参数、几何尺寸、外荷载幅值以及控制力的随机性对结构闭环控制系统动力响应的影响，并获得了若干有意义的结论．     

销钉对FCP电位测试精度影响之BEM分析

本文用边界元法对销钉接触角及销钉孔半径对三种电流输入方式下紧凑拉伸试样的电位函数影响进行了分析。结果证明,人们在电位法测试中常用的电流输入方式容易引起误差,并非最佳方案.最佳方案是另一种同样方便的电流输入方式.     

校准蒸发光散射检测器选用标准物质的比较与分析

通过对葡萄糖和三氯蔗糖的物理、化学性质的比较,采用高效液相色谱仪和蒸发光散射检测器进行标准溶液色谱峰面积的检测,并用G rubbs检验法对其数据进行异常值检验。结果表明,三氯蔗糖相对于葡萄糖较为稳定,选用三氯蔗糖作为蒸发光检测器校准用标准物质比较合适。     

Thermal stability and flame-retardancy mechanism of poly(ethylene terephthalate)/boehmite nanocomposites

The thermal stability and flame-retardancy properties of poly(ethylene terephthalate)/nano-boehmite composites (PET/AlOOH) were investigated using composites prepared in situ. Combustion behaviour and flammability were assessed using the limiting oxygen index (LOI) and cone calorimetry. The incorporation of nano-boehmite increased the LOI of PET from 18 to greater than 25. Cone calorimetry showed that the heat release rates and total smoke production values of PET/AlOOH composites were significantly less than those of pure PET. It also showed that PET/AlOOH combustion produced greater quantities of char residues than did PET combustion. These results showed that nano-boehmite is an effective flame-retardant for PET. Combustion residues were examined using scanning electron microscopy, indicating that nano-boehmite addition produced consistent, thick char crusts. Thermal stability and pyrolysis were investigated using thermogravimetric analysis and pyrolysis-gas chromatography-mass spectrometry, showing that thermal stability of PET/AlOOH was superior to that of pure PET, fewer cracking products were produced in nanocomposite combustion than in pure PET combustion, and pyrolysis of the flame-retardant polyester was incomplete. We propose a condensed phase mechanism for the PET/AlOOH flame-retardancy effect.     

Enantioselective Resolution of γ-Lactam by a Whole Cell of <Emphasis Type="Italic">Microbacterium hydrocarbonoxydans</Emphasis> (L29-9) Immobilized in Polymer of PVA–Alginate–Boric Acid

Using immobilized cells of a novel strain of Microbacterium hydrocarbonoxydans L29-9 in polymers of polyvinyl alcohol (PVA)–alginate–boric acid, enantioselective resolution of racemic γ-lactam to produce (−)γ-lactam was successfully carried out. A 6:1 ratio of PVA:sodium alginate not only prevented agglomeration of the matrix but also produced beads with high gel strength. The optimum biotransformation conditions were 1 g/L substrate, pH 7.0, reaction temperature of 30 °C, and reaction time of 3 h. After every two cycles, the immobilized cell beads were separated and immersed in 0.5 mM KCl solution at 4 °C for preservation. At optimum conditions, the enantiomeric excess and the yield of (−)γ-lactam were >99% and 34%, respectively. The beads showed a slight decrease in the enantiomeric excess when re-used up to 14 cycles (the enantioselectivity of the immobilized cells decreased slightly after 14 cycles of usage).