Synthesis of a structure proposed for scotophobin

Zusammenfassung Es wurde ein biologisch interessantes Polypeptid mit der für Scotophobin vorgeschlagenen Sequenz synthetisiert. Da dieses nur eine geringe biologische Aktivität besass, wird angenommen, dass die für das natürliche Produkt vorgeschlagene Strukturformel nicht korrekt ist.

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We thank the National Institutes of Health (MH 19320) for the support of this work.     

利用模拟退火算法对200 MW供热堆堆芯核设计的优化

对 2 0 0 MW核供热堆装载模式 (燃料组件布置、可燃毒物棒根数和可燃毒物质量分数配置 )进行了优化。利用模拟退火算法和先进格林函数节块法进行多步燃耗优化计算。引入敏感性系数 ,并通过敏感性分析的方法决定优化参数 ,因此在单目标和多目标优化时均取得了明显的效果。对组件布置和可燃毒物质量分数的优化计算结果表明 ,在不改变原有的富集度和组件类型的前提下 ,与参考值相比 ,优化后的循环长度、功率峰因子和卸料燃耗均有明显的改善。该燃料管理方法不仅可用于低温堆而且也可以推广到压水堆     

Dynamic Analysis of Cable Roofs Under Transient Wind:A Comparison Between Time Domain and Frequency Domain Approaches

At present, high-speed computing capabilities and advanced nonlinear dynamic finite element procedures enable detailed dynamic analysis of cable structures. Although deterministic approaches require considerable analysis time and effort in relation to modeling, running, and data processing, they seem to be the only alternative to obtain high accuracy. Detailed dynamic analysis of cable roof networks is sophisticated and requires advanced modeling expertise. This paper presents a comparison between detailed nonlinear dynamic analysis and a simplified frequency domain approach to estimate the maximum probable response of weakly nonlinear cable roofs. The approach can be considered as alternative to detailed time-domain analysis in the preliminary design phase, or can be used to validate results obtained from more elaborated numerical models. The proposed method is illustrated with two examples of cable net roofs that were also analysed in the time domain.     

Sample average approximation method for a class of stochastic variational inequality problems

This paper considers a class of stochastic variational inequality problems. As proposed by Jiang and Xu (2008), by using the so-called regularized gap function, the authors formulate the problems as constrained optimization problems and then propose a sample average approximation method for solving the problems. Under some moderate conditions, the authors investigate the limiting behavior of the optimal values and the optimal solutions of the approximation problems. Finally, some numerical results are reported to show efficiency of the proposed method.     

A TEM study on the microstructure of spark plasma sintered ZrB_2-based composite with nano-sized SiC dopant

Sintering behavior of ZrB₂ ceramic with nano-sized SiC dopant was studied. ZrB₂-25 vol% nano-sized SiC was selected as the starting mixture to fabricate the composite. The manufacturing process was accomplished at 1800℃ for 5 min under 25 MPa via spark plasma sintering(SPS). The as-sintered sample reached a relative density of 99%. Besides the initial phases, namely ZrB₂ and SiC, the high-resolution X-ray diffraction(HRXRD) was used to study the formation of an i...     

Effect of SrCO<Subscript>3</Subscript> addition on the dynamic compressive strength of ZTA

Ceramic parts usually experience dynamic load in armor applications. Therefore, studying the dynamic behaviors of ceramics is important. Limited data are available on the dynamic behaviors of ceramics; thus, it is helpful to predict the dynamic strength of ceramics on the basis of their mechanical properties. In this paper, the addition of SrCO₃ into zirconia-toughened alumina (ZTA) was demonstrated to improve the fracture toughness of ZTA due to the formation of the SrAl₁₂O₁₉ (SA6) phase. The porosity of ZTA was found to be increased by the addition of SrCO₃. These newly formed pores served as the nucleation sites of cracks under dynamic load; these cracks eventually coalesced to form damaged zones in the samples. Although the K IC values of the samples were improved, the dynamic strength was not enhanced because of the increase in porosity; in fact, the dynamic strength of ZTA ceramics decreased with the addition of SrCO₃.     

Fluctuating stripes at the onset of the pseudogap in the high-T(c) superconductor Bi(2)Sr(2)CaCu(2)O(8+x)

Doped Mott insulators have a strong propensity to form patterns of holes and spins often referred to as stripes. In copper oxides, doping also gives rise to the pseudogap state, which can be transformed into a high-temperature superconducting state with sufficient doping or by reducing the temperature. A long-standing issue has been the interplay between the pseudogap, which is generic to all hole-doped copper oxide superconductors, and stripes, whose static form occurs in only one family of copper oxides over a narrow range of the phase diagram. Here we report observations of the spatial reorganization of electronic states with the onset of the pseudogap state in the high-temperature superconductor Bi(2)Sr(2)CaCu(2)O(8+x), using spectroscopic mapping with a scanning tunnelling microscope. We find that the onset of the pseudogap phase coincides with the appearance of electronic patterns that have the predicted characteristics of fluctuating stripes. As expected, the stripe patterns are strongest when the hole concentration in the CuO(2) planes is close to 1/8 (per copper atom). Although they demonstrate that the fluctuating stripes emerge with the onset of the pseudogap state and occur over a large part of the phase diagram, our experiments indicate that the stripes are a consequence of pseudogap behaviour rather than its cause.     

发展中国家的历史文化名城保护

发展中国家的历史文化名城保护纳吉波②（东南大学建筑系，南京２１００１８）由于各国文化背景和经济建设状况不同，对历史文化遗产的保护在时间和深度上都存在差异．发达国家对历史文化遗产的保护较早，特别是保护那些保留了整个地区文物建筑及历史风貌的城镇，从而形...