Design of polarization-maintaining retro-reflector for folded-path applications

A design of polarization-maintaining retro-reflectors(PMRRs) for folded-path applications is proposed and analyzed.The prism-based scheme enables the output light,which is parallel to the input,to have an identical state of polarization.The principle of the design is theoretically verified,and the related error is analyzed due to possible manufacturing imperfection.The maximum spatial angle error is ±2.75°.The effect on the extinction ratio and insertion loss is also discussed,which further proves the design’s feasibility in practical applications.     

An Efficient Synthesis of Racemic and Optically Active Telluromethionine

A direct and efficient route for the construction of racemic and optically active L-telluromethionine (L-Te-Met) starting from the readily available hydrochloride salt of α-amino-γ-butyrolactone and lithium methyltellurolate is described. The reaction has been successfully scaled up to afford gram quantities of L-Te-Met in 75–80% yield.     

裂缝的张开位移和应变的关系

本文采用Kármán-钱处理亚音速流动方法的精神。处理了弹塑性断裂力学问题.通过建立的“双弹性”模型,从理论上得到了裂缝端部的张开位移和应变的方程组.实例计算结果表明,理论值全部落在实验结果的分散带内.文中并从理论上解释了实验结果与材料的性质及实验条件的关系.本文的结果不仅为宽板实验所证实,也被文献[2]的实验所证实.同时也表明。公式(37)用于工程,能够分析压力容器上应变裂缝的容许极限.     

“下愚”最智 “上智”最愚

历代反动派总是宣扬孔老二“上智与下愚不移”的唯心论说教,把它作为“剥削有理”、“压迫有理”的根据。林彪这个地主资产阶级的代理人,为了篡党夺权,复辟资本主义,建立林家法西斯王朝,也鼓吹“上智下愚”的谬论。他把自己吹成“生而知之”的“天才”,以“至贵”、超人自居,污蔑劳动人民“愚昧”、“落后”,只会说“恭喜发财”,只能想“油盐酱醋柴”。     

Effects of magnetic atoms on the properties of ternary superconductors

Conclusion It is noteworthy that while only two classes of systems (the Chevrel phases and the rare-earth rhodium borides) have so far received extensive study, nonetheless a great many new phenomena have been encountered. This, however, should only be considered the beginning of a new and potentially very rich field, especially if one considers the vast number of possibilities of ternary compounds that can be produced. To take only one other example, recent work has shown that the compound Sc₂Fe₃Si₅ is superconducting with a superconducting transition of 4.5 K (29). This at first may appear surprising since ever in the Chevrel phase materials, the addition of Fe atoms is detrimental to superconductivity. However, recent Mossbauer effect experiments (29) have shown that the Fe in this material is not magnetic, having a magnetic moment of less than 0.03 µ_B. These silicides have also been made with rare-earth ions in place of the Sc(²⁸). The compounds show magnetic transitions and are currently under investigation. Several other interesting systems have been synthesized, and it appears that many more will be coming in the near future. The results reported above have shown the utility of hyperfine data in clarifying many of the new phenomena that occur, and it should be expected that as this new field grouws, these kinds of measurements will continue to play an active role (30).     

A Mössbauer effect investigation of the enstatite chondrite from Abee, Canada

The results of a room temperature ⁵⁷Fe Mössbauer effect investigation of the enstatite chondrite meteorite which fell in Abee, Alberta, Canada in 1952, are presented. Analysis of the spectrum indicates that Fe is present in the form of kamacite, taenite (both ferromagnetic and paramagnetic phases), troilite and niningerite in sufficient quantity to be readily identified. The hyperfine parameters for each of these phases is interpreted on the basis of chemical and electron microprobe studies of Abee and are consistent with expectations based on stoichiometry.     

β-d-Xylosidase from Selenomonas ruminantium of glycoside hydrolase family 43

Beta-D-xylosidase from the ruminal anaerobic bacterium, Selenomonas ruminantium (SXA), catalyzes hydrolysis of beta-1,4-xylooligosacharides and has potential utility in saccharification processes. The enzyme, heterologously produced in Escherichia coli and purified to homogeneity, has an isoelectric point of approx 4.4, an intact N terminus, and a Stokes radius that defines a homotetramer. SXA denatures between pH 4.0 and 4.3 at 25 degrees C and between 50 and 60 degrees C at pH 5.3. Following heat or acid treatment, partially inactivated SXA exhibits lower k(cat) values, but similar K(m) values as untreated SXA. D-glucose and D-xylose protect SXA from inactivation at high temperature and low pH.     

Symmetry properties of spin-polarized leed

The transformational properties of the polarizing power $\text{P}$ and the analyzing power $\text{S}$ of a polarized LEED beam under time reversal, rotations and reflections are derived. A general relationship between $\text{S}$ and $\text{P}$ is given, and special cases of equality are noted.     

1,2,4-Triazoles—XXXI: Photodimerization of s-triazoleo[4,3-a]pyridines: formation of cyclobutane dimers

Irradiation of several methyl substituted s-triazolo[4,3-a]-pyridines and 3-hydroxy-s-triazolo[4,3-a]pyridines with UV light gave thermally labile cyclobutane photodimers by dimerization of the 5,6-double bond in one molecule with the 7,8-double bond in another.