HL-2M 装置电子回旋共振加热及电流驱动系统设计与研制进展

根据 HL-2M 装置物理实验加热的需求,完成了总功率为 8MW 的电子回旋共振加热及电流驱动 (ECRH/ECCD)系统设计,开展了波源、传输及天线等关键部件研制。8MW ECRH/ECCD 系统,由 8 套 105GHz/  1MW/3s 波源系统、8 条内径为 63.5mm 的真空传输线及三套极向实时可控的发射天线构成。目前,已完成 ECRH/ECCD 系统关键部件研制及其相关的桌面与高功率性能测试。测试结果表明,微波源回旋管输出微波功率 达到1MW/3s,在真空度为 10^‒2Pa 的过模波纹圆波导传输线中能低耗稳定传输,发射天线极向全量程角度转动响 应时间在 50ms 以内。      

The synthesis and inhibitory activity of dethiotrypanothione and analogues against trypanothione reductase

Trypanothione reductase (TR) catalyzes the NADPH-dependent reduction of trypanothione disulfide (1). TR plays a central role in the trypanosomatid parasite's defense against oxidative stress and has emerged as a promising target for antitrypanosomal drugs. We describe the synthesis and activity of dethiotrypanothione and analogues (2-4) as inhibitors of Trypanosoma cruzi TR. The syntheses of these macrocycles feature ring-closing olefin metathesis (RCM) reactions catalyzed by ruthenium catalyst 17. Derivative 4 is our most potent inhibitor with a Ki=16 microM.     

Year of birth determination using radiocarbon dating of dental enamel

Radiocarbon dating is typically an archaeological tool rather than a forensic one. Recently however, we have shown that the amount of radiocarbon present in tooth enamel, as a result of nuclear bomb testing during the cold war, is a remarkably accurate indicator of when a person is born. Enamel isolated from human teeth is processed to form graphite and carbon-14 ((14)C) levels are measured using accelerator mass spectrometry. Since there is no turnover of enamel after it is formed, (14)C levels in the enamel represent (14)C levels in the atmosphere at the time of its formation. In this paper we describe the strategy used to determine the date of birth of an individual based on radiocarbon levels in tooth enamel, focusing on the methodology of this strategy. Year of birth information can significantly assist police investigators when the identity of a deceased individual is unknown. In such cases police will try to match particulars of the unidentified individual (which is often only gender and/or an estimate of age), with particulars from missing persons lists.     

Numerical analysis of waveguide-enhanced optical bistability

We present the results of a simulation study of a multilayer structure for which strongly enhanced (resonant) electric fields are produced at the surface of, and in the interior of, a planar waveguide which is evanescently coupled to an incoming beam in a prism geometry. The resulting field enhancements can far exceed those associated with the well-known surface plasmon resonance in a typical silver film excited in the conventional attenuated total reflection geometry. Simulations are performed for optical bistability for the case of a typical YAG laser beam coupled to a zinc oxide (ZnO) waveguide, demonstrating that the effect should occur for reasonable values of the parameters involved.     

Steady turbulent flow and heat transfer downstream of a sudden enlargement in a pipe of circular cross-section

Stream-line and temperature contours, and the corresponding fluxes at the walls, are computed by numerical solution of the elliptic transport equations of vorticity, enthalpy and turbulence energy, together with auxiliary relations comprising a turbulence model similar to that of Prandtl [19]. The length-scale distribution is determined empirically in order to ensure that the recirculation region has the right length, and the maximum of the wall heat flux occurs at the right place, but the other empirical inputs have values which are determined from quite different experiments. — Agreement between predictions and experimental data of Krall and Sparrow [13] is good. In particular, the correct exponent is predicted for the Stanton number ? Reynolds number law. This exponent is uninfluenced by the length-scale distribution. — For practical use, it is argued, the Prandtl turbulence model needs to be replaced by one embodying two differential equations for turbulence quantities.