论钱学森的大成智慧学

文章强调 "大成智慧学"是新世纪的需要, "大成智慧"的核心是科学技术与哲学的结合。为此,不仅要利用人-机结合的思维体系,下苦功夫掌握广博的知识、经验、信息,还要从实际出发,实事求是,善于思考,反复实践,努力树立起反映新世纪的世界观、人生观、科学观、方法论。     

Giant traps on the surface of hydride vapor phase epitaxy-grown free-standing GaN

Extended defects on the top surface of a 250-μm-thick free-standing GaN sample, grown by hydride vapor phase epitaxy (HVPE), were studied by deep level transient spectroscopy (DLTS) and scanning surface potential microscopy (SSPM). For comparison, similar studies were carried out on as-grown HVPE-GaN samples. In addition to the commonly observed traps in as-grown HVPE-GaN, the DLTS measurements on free-standing GaN reveal a very high concentration of deep traps (∼1.0 eV) within about 300 nm of the surface. These traps show nonexponential capture kinetics, reminiscent of those associated with large defects, that can accumulate multiple charges. The SSPM measurements clearly reveal the presence of charged microcracks on the top surface of the sample. It appears that the “giant traps” may be associated with these microcracks, but we cannot rule out the involvement of other extended defects associated with the near-surface damage caused by the polishing/etching procedure.     

Transport Property of La0.67-xSmxSr0.33MnO3 at Heavy Samarium Doping (0.40≤x≤0.60)

The influence of heavy samarion (Sm) doping(0.40≤x≤0.60) on magnetic and electric properties of La0.67-xSmxSr0.33MnO3 was investigated by measuring the magnetization-temperature (M～T) curves, magnetization-magnetic density (M～H) curves, resistivity-temperature(ρ-T) curves and magnetoresistivity-temperature(MR～T) curves of the samples under different temperatures.It is found that, with the increase of Sm doping amount, the samples transform from long-range ferromagnetic order to spin-cluster glass state and anti-ferromagnetic state;and when x=0.60, the transport property becomes abnormal under magnetic background;and the magnetic structure changes and extra magnetic coupling induced by doping leads to colossal magnetoresistance effect.The transport mechanism of metallic conduction at low temperature is mainly electron-magneton interaction and can be fitted by the formula ρ=ρ0 AT4.5, and the insulator-like transport mechanism on high temperature range is mainly the function of variable-range hopping and can be fitted by the formula ρ=ρ0exp(T0/T)1/4.In the formulas above, ρ is resistivity, T is temperature, and A, ρ0, T0 are constants.     

从复杂性的角度分析供应链管理问题

供应链是企业适应市场环境变化而产生的运作模式,也是企业之间竞争与协同发展的产物。供应链是由多个企业组成的复杂供需网络,因此它属于开放的复杂巨系统的范畴,而处理开放的复杂巨系统的有效方法是综合集成研讨体系。该文首先介绍了复杂性的研究情况;分析了供应链的复杂性;指出供应链是一个开放的复杂巨系统;提出用综合集成研讨厅体系的思想研究供应链管理问题,为供应链管理问题的研究提供了一个新的思路。     

Giant magnetoresistance effect in Ni buffered Co/Cu/Co sandwich

The effects of Ni buffer layer on the giant magnetoresistance structure of Co/Cu/Co sandwich are investigated systematically in this paper. It is found that Ni buffer layer can induce the crystallization of the lower Ni/Co layer and produce small coercivity, thus enlarging the difference in the magnetic behavior between the two magnetic layers in the sandwich. Moreover, the use of the Ni buffer layer can also improve the interface flatness in the sandwich. All these factors enhance the sensitivity of the Ni buffered sandwich.     

Static Ferromagnetic Modulation Revealed by Neutron Scattering in La1?xCaxMnO3

Mn perovskites La_1–x Ca _x MnO₃ (0x0.1) have been studied by small angle neutron scattering (SANS) and elastic neutron scattering (ESANS). At low temperature, both experiments reveal a broad modulation centered at the same q _m whatever the q direction. This scattering pattern is typical of a liquid-like distribution of similar magnetic droplets, or large magnetic polarons.     

Gene expression within cell-sized lipid vesicles

Functional protein synthesis was observed in cell-sized lipid vesicles following encapsulation of a gene-expression system. Expression of rsGFP (red-shifted green fluorescent protein) within individual vesicles was observed by fluorescence microscopy. Interestingly, at the early stage of the reaction, the expression efficiency inside the vesicle was remarkably higher than that in the solution outside. The synthesized rsGFP in individual vesicles is safe from attack by proteinase K added to the external aqueous solution. Studies on cell-sized vesicles expressing protein should contribute to a fundamental understanding of certain aspects of living systems and will be useful for practical applications, such as the construction of microreactors.     

以低纯度钆研究Gd5Si2Ge2的磁热效应及制备工艺

以99%级的低纯度金属Gd为原料, 采用真空感应炉制备工艺, 辅以1470 K热处理工艺, 获得了与99.99%级高纯度Gd为原料制备的Gd5Si2Ge2合金相近的磁热效应, 5 T外场下最大磁熵变达17.5 J·kg^-1·K^-1, 对比电弧熔炼与感应熔炼两种制备方法, 感应熔炼条件下C, N, O杂质含量明显降低, 发现了Gd5Si2Ge2合金巨磁熵变与相结构的本质联系.     

高检测灵敏度的DNA生物传感器

基于磁珠带标记DNA电化学传感器、磁珠标记的GMR(TMR)DNA生物传感器和纳米线场效应DNA生物传感器都具有高检测灵敏度的特点,是极具发展前途的研究方向。主要介绍了以上三种高检测灵敏度DNA生物传感器的基本检测原理,并对比分析了这三种传感器的优缺点。