1．5GHz锯材超导腔的研制

介绍铌材超导腔的研制进展，重点讨论了国产铌腔的材料改性，以及相应的超导腔性能的改进．叙述了１．５ＧＨｚ铌腔的腔形设计，分析了铌材的射频性能和机械性能，制定了铌腔制作与后处理的特定工艺．最后给出了１．５ＧＨｚ铌材超导腔的低温实验结果．     

An evolutionary method for optimization of plate buckling resistance

Optimization of plate buckling resistance is very complicated, because the in-plane stress resultants in the prebuckled state of a plate are functions of thickness distribution. This paper discusses the problem of finding the optimum thickness distribution of isotropic plate structures, with a given volume and layout, that would maximise the buckling load. A simple numerical method using the finite-element analysis is presented to obtain the optimum thickness distribution. Optimum designs of compression-loaded rectangular plates with different boundary conditions and plate aspect ratios are obtained by using the proposed method. Optimum designs from earlier studies and the methods of buckling analysis used to attain these results are discussed and compared with the designs from the proposed method. This paper also examines the reliability of the optimality criterion generally used for plate buckling optimization, which is based on the uniform strain energy density.     

Continuity properties of the normal cone to the level sets of a quasiconvex function

Two main properties of the subgradient mapping of convex functions are transposed for quasiconvex ones. The continuity of the functionxf(x)^–1f(x) on the domain where it is defined is deduced from some continuity properties of the normal coneN to the level sets of the quasiconvex functionf. We also prove that, under a pseudoconvexity-type condition, the normal coneN(x) to the set {x:f(x)f(x)} can be expressed as the convex hull of the limits of type {N(x _n)}, where {x _n} is a sequence converging tox and contained in a dense subsetD. In particular, whenf is pseudoconvex,D can be taken equal to the set of points wheref is differentiable.This research was completed while the second author was on a sabbatical leave at the University of Montreal and was supported by a NSERC grant. It has its origin in the doctoral thesis of the first author (Ref. 1), prepared under the direction of the second author.The authors are grateful to an anonymous referee and C. Zalinescu for their helpful remarks on a previous version of this paper.     

A supported gold catalyst for the elimination of hydrogen from CO2 feed gas in the production of urea

Supported gold catalyst for eliminating hydrogen from CO₂ feed gas in the production of urea is found to be superior to other industrial catalysts (e.g. Pt/Al₂O₃ and PdPt/Al₂O₃) in catalytic activity and resistance to sulfur poisoning.     

SYNTHESIS AND PHOTOCHROMISM OF ACRYLIC ESTER COPOLYMERS BEARING PENDANT VIOLOGEN GROUPS

A series of acrylic ester copolymers with viologen group as pendant were synthesizedthrough the reaction of MMA-EBA (Ethenyl bromoacetate) copolymer with 4-(4'-pyridyl)-N-alkyl (or arylalkyl) pyridiniums. These viologen copolymers can exchange their anionwith NH_4PF_6 in methanol to improve their solubility in organic solvents such as DMFand acetone. Compared with the corresponding low molecular viologens, these viologencopolymers have relatively lower color development rate under UV light and fade fasterin air due to less affinity to photo-reductant and deficiency of association between theircation radicals. Their photofatigue resistant ability is also slightly better than that of lowmolecular vinlogens.     

A scratch-resistant single-layer antireflective coating by a low temperature sol-gel route

A novel quarterwave-thick narrow-bandwidth antireflective coating has been developed for both plastic and vitreous substrates by a sol-gel route. This coating has revealed pronounced scratch- and climatic-resistance under adverse conditions. The single-layer coating consists basically of a composite material made of silica as the discontinuous phase and of a polytetrafluoroethylene-derived (Teflon¹) organic polymer as the continuous phase. This leads to fluorine-containing colloidal silica product, or a so-called Flucosil coating. The coating is applied by spinning or dipping from specific solutions at room temperature followed by a mild and short heat treatment. In addition to remarkable abrasion and environmental resistance properties, such coatings have displayed excellent laser-induced damage threshold levels, surpassing uncoated substrates.We hope such a product might open new perspectives concerning household articles, architectural optical thin-films, ophthalmic uses, and so on.     

Toward breast cancer resistance protein (BCRP) inhibitors: design, synthesis of a series of new simplified fumitremorgin C analogues

In this study, we report the design and synthesis of a series of new simplified fumitremorgin C analogues. The preliminary biological study indicated some of these simplified fumitremorgin C might be developed into breast cancer resistance inhibitors.     

化学复合镀Ni-P-PTFE镀层的组成分析

近年来化学复合镀技术在工业中应用日益广泛 ,本文运用ＳＥＭ、ＡＥＳ和ＸＰＳ等手段对用化学复合镀制得的Ｎｉ Ｐ ＰＴＦＥ镀层的结构和组分进行了分析 ,并就其耐腐蚀性能与前期得到的Ｎｉ Ｓｎ Ｐ[1 ] 、Ｃｕ Ｓｎ Ｐ[2 ] 、Ｎｉ Ｐ ＣｅＯ2 [3] 、Ｎｉ Ｐ ＳｉＯ2 [4] 镀层进行了比较 ,结果表明 :含量一定的ＰＴＦＥ(聚四氟乙烯 )的共存增强镀层的耐腐蚀性及镀层表面的润滑性。1　实验部分1 1　仪器日产Ｄ/ＭＡＸⅢＡ型Ｘ 射线衍射仪 ,铜靶 ,管压 2 5ｋＶ ,电流 1 0ｍＡ。国产ＪＪＣ 1型润滑湿角测量仪。美国ＰＥＲＫＩＮ ＥＬＭＥＲＰ…     

代铬刷镀层的耐腐蚀机理的考察

对新型的代铬刷镀层Ni-Fe-W-P-S进行了耐腐蚀性能机理的分析研究。用扫描电镜(SEM)、透射电镜(TEM)、扫描隧道显微镜(STM)、X射线衍射及电子能谱(XPS)等的分析表明，基体组织为非品结构是代铬刷镀层优异耐腐蚀性的主要原因.     

Y2O3薄膜处理对3Cr25Ni7N合金的抗高温氧化性能的影响

采用电沉积-热解法在3Cr25Ni7N合金表面制备了Y2O3薄膜,并研究了薄膜处理对合金在1000℃空气中的抗高温氧化性能的影响。氧化动力学曲线、SEM及XRD分析结果表明,Y2O3薄膜处理使合金表面氧化膜以尖晶石结构为主,氧化膜致密,有效地抑制了Cr2O3的挥发反应,且氧化膜与基体的附着性好,因此合金在高温下的抗氧化性能得到提高,这与氧化钇薄膜在较低温度下抗高温氧化性能提高的机制是不同的。在不同温度下,Y2O3薄膜处理均可以有效提高合金的抗高温氧化性能。