Determination of sphingosine kinase activity in biological samples by liquid chromatography–tandem mass spectrometry

Sphingosine kinase (SphK) is a key enzyme in modulating the levels of sphingosine 1‐phosphate (S1P) as well as an important enzyme in numerous biological responses. Using C17‐sphingosine as a substrate, we established a rapid, sensitive and highly efficient method for determination of SphK activity by analyzing the product C17‐sphingosine 1‐phosphate (C17‐S1P) using liquid chromatography–tandem mass spectrometry. The standard curve for C17‐S1P was linear over a wide range (10–1000 ng/mL) with correlation coefficient (r²) greater than 0.999. The lower limit of quantification for C17‐S1P was 10 ng/mL. The K_m values for C17‐sphingosine and ATP were determined to be 28.17 and 188.5 mM, respectively. More importantly, the SphK activity dramatically increased in cultured HEK 293 cells expressing wild‐type SphK1 as well as cells treated with tumor necrosis factor‐a, a sphingosine kinase activator. In contrast, the SphK activity decreased in cultured HEK 293 cells treated with dimethylsphngosine, a sphingosine kinase inhibitor. In conclusion, this method was sensitive and rapid in the determination of SphK acitivity, providing striking utilities in exploring the sphingosine kinase signaling pathway and screening active compounds targeting SphK activity. Copyright © 2010 John Wiley & Sons, Ltd.     

Mechanochemical-synthesized Al-doped manganese dioxides for electrochemical supercapacitors

Al-doped MnO₂ as electrode materials for supercapacitor were synthesized by high-energy ball milling. The morphologies and structures of prepared MnO₂ were studied by scanning electron microscopy (SEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Electrochemical investigation indicated that doped MnO₂ presented preferable electrochemical performances than un-doped MnO₂, but there were obvious capacitance decline in the first several dozen of cycles for all doped MnO₂ samples. The Al_0.05/Mn_0.95O₂ electrode, especially, showed the largest capacitance among all prepared MnO₂ samples. Excellent conductivity of Al in doped MnO₂ was considered to be responsible for enhanced electrochemical performances of doped MnO₂.     

对井冈山红色旅游资源开发的思考

随着红色旅游热的升温,红色旅游资源开发在全国风起云涌。红色旅游不同于传统的观光旅游和文化旅游,它有自己独特的涵义和开发规律。鉴于红色旅游发展时间较短,作为＂中国红色旅游基地之首＂的井冈山在红色旅游资源开发也还有不成熟的地方。本文通过对井冈山红色旅游资源开发现状的分析,总结了目前其存在的主要问题,并在此基础上提出井冈山红色旅游资源开发的可持续发展对策。     

基于CS模式的多机器人网络通信系统

首先提出了基于CS模式的多机器人通信系统的拓扑结构，并对这种通信模式的一致性响应速度特性进行了分析，然后给出了基于Visual C＋＋MFC的CS网络通信模式的程序设计方法，最后对系统进行了实验验证．研究表明，基于CS的多机器入网络通信系统，具有结构简单、一致性速度快的优点，对建立多机器人通信系统具有较大的指导意义．     

Microfabrication techniques using focused ion beams and emergent applications.

The application of focused ion beam (FIB) machining in several technologies aimed at microstructure fabrication is presented. These emergent applications include the production of micromilling tools for machining of metals and the production of microsurgical tools. An example of the use of microsurgical manipulators in a circulatory system measurement is presented. The steps needed to transform the laboratory fabrication of these tools and manipulators into a routine FIB production process are discussed. The ion milling of three-dimensional cavities by the exact solution of a mathematical model of the FIB deflection is demonstrated. A good agreement between the model calculation and the ion beam control has been obtained for parabolic and cosine cross-section features with planes of symmetry.     

Mei symmetry and Mei conserved quantity of nonholonomic systems with unilateral Chetaev type in Nielsen style

This paper studies the Mei symmetry and Mei conserved quantity for nonholonomic systems of unilateral Chetaev type in Nielsen style. The differential equations of motion of the system above are established. The definition and the criteria of Mei symmetry, loosely Mei symmetry, strictly Mei symmetry for the system are given in this paper. The existence condition and the expression of Mei conserved quantity are deduced directly by using Mei symmetry. An example is given to illustrate the application of the results.     

Effect of thermal-annealing on the magnetoresistance of manganite-based junctions

Thermal-annealing has been widely used in modulating the oxygen content of manganites. In this work, we have studied the effect of annealing on the transport properties and magnetoresistance of junctions composed of a La0.9Ca0.1MnO3＋6 film and a Nb-doped SrTiO3 substrate. We have demonstrated that the magnetoresistance of junctions is strongly dependent on the annealing conditions： Prom the junction annealed-in-air to the junction annealedin-vacuum, the magnetoresistance near 0-V bias can vary from ～-60% to N～0. A possible mechanism accounting for this phenomenon is discussed.     

Optimized transfer trajectories in the earth-moon system

Investigations of low energy transfer trajectories are important for both celestial mechanics and astronautics. Methodologies using the theories from dynamical systems are developed in recent years. This paper investigates the dynamics of the earth-moon system. Low energy transfer trajectories are solved numerically by employing a hybrid strategy： first, a genetic hide and seek method performs a search in large domain to confine the global minimum f（η） （objective function） region; then, a deterministic Nelder-Mead method is utilized to refine the minimum quickly. Some transfer trajectories of the spacecraft in the earth-moon system are successfully simulated which verify the desired efficiency and robustness of the method of this paper.     

Scheme for the implementation of 1→3 optimal phase-covariant quantum cloning in ion-trap systems

This paper proposes a scheme for the implementation of 1→ 3 optimal phase-covariant quantum cloning with trapped ions. In the present protocol, the required time for the whole procedure is short due to the resonant interaction, which is important in view of decoherence. Furthermore, the scheme is feasible based on current technologies.