横向剪变形对具有一小圆孔的浅壳应力集中系数的影响

本文导出了分析计及横向剪变形的浅壳小孔应力集中问题的简化方程.对浅球壳和圆柱壳带一小圆孔的情况,获得了方程的级数形式通解.对均匀内压作用下的圆柱壳,求得了小圆孔边上应力集中系数的近似显式解,并计算了数值结果.     

Synthesis and characterization of cyclic pseudopeptide libraries containing thiomethylene and thiomethylene-sulfoxide amide bond surrogates

We describe the first examples of a series of cyclic pseudopeptide libraries that have been prepared in a systematic approach in order to facilitate both synthesis and subsequent deconvolution attempts. Our synthetic strategy involved the attachment of a trifunctional amino acid (Asp, Asn or Glu) to a polystyrene resin via its side chain, and stepwise chain elongation using either protected amino acids or a pseudodipeptide building block. Head to tail cyclic peptides were formed by removal of the temporary N- and C-terminal protecting groups followed by ring closure by amide formation. Cyclization of the hexa, hepta, and octapseudopeptides on the resin avoided dimer formation, as monitored by mass spectrometry. We utilized a psi-scan approach in which a second fixed position was serially addressed by stepping a dipeptide surrogate, Pro[CH₂S]Gly around the rings to generate a group of cyclic pseudopeptide sub-libraries. Oxidation of [CH₂S] to [CH₂SO] helped validate the synthesis and also provides a strategy for forming a new set of pseudopeptide libraries (previously described as libraries from libraries). Our results suggest that libraries of cyclic pseudopeptides are an efficient method of preparing and assaying these synthetically more challenging entities as potential drug leads.     

Location Matters: Site of Conjugation Modulates Stability and Pharmacokinetics of Antibody Drug Conjugates

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Highlights? Site-specific conjugation of diverse payloads can be achieved with transglutaminase ? Efficient conjugation was achieved at multiple positions throughout an antibody ? Site of conjugation has significant impact on ADC stability and pharmacokinetics ? Differences in ADC stability and pharmacokinetics are species dependent     

SIMS depth profiling of vertical p-channel Si-MOS transistor structures

SIMS depth profiling during O₂ ⁺ bombardment has been performed to analyse epitaxially grown Si p-n-p layers, which define the p-channel region in vertical Si-p MOS transistors, as well as to establish “on-chip” depth profiling of the functional vertical device. The SIMS detection limit of ³¹P in Si, phosphorus used as n-type dopant in the transistor, has been optimised as a function of the residual gas pressure in the SIMS analysis chamber and of the sputter erosion rate. We demonstrate that good vacuum during SIMS analysis combined with high erosion rates allows the simultaneous quantitative SIMS depth profiling of n- and p-type dopant concentrations in the vertical transistor. Small area “on-chip” SIMS depth profiling through the layered structure of Al-contact/TiSi₂/Si(p-n-p)/Si-substrate has been performed. Factors influencing the depth resolution during “on-chip” analysis of the transistor are discussed especially in terms of sputtering induced ripple formation at the erosion crater bottom, which has been imaged with atomic force microscopy. Received: 15 August 1996 / Revised: 17 January 1997 / Accepted: 21 January 1997     

FINITE LAYER ANALYSIS FOR SEMI-INFINITE SOILS (Ⅱ)——SPECIAL CASES AND NUMERICAL EXAMPLES

In the present paper reductions of the finite layer mathod once studied in detail by the authors for the elastodynamies of transverse isotropic bodies are given to several special cases. Two-dimensional problems, axisymmetric problems and static problems are discussed, respectively, and this Jinite layer method is also generalized to the problems in which materials possess viscous properties. Two numerical examples have been presented for the axisymmetric case. From these two examples it can be concluded that the finite layer method can be used to analyse semi-infinite layered soils and to deal with the problem of the interaction between soils and structvres.     

分析土壤半无限域的一种有限层方法(Ⅱ)——几种特殊情形及算例*

本文就几种特殊情形用作者所研究的一种用于横观各向同性体动力学的有限层法作了简化分析,分别讨论了二维问题、轴对称问题以及静力问题,并推广到介质具有粘性性质的情形.对于轴对称情形,本文还给出两个算例,表明作者所研究的有限层法用于分析半无限域层状土壤介质是可行的,因而为研究土壤与结构相互作用问题提供了一条新途径.     

Crystal growth and electrical conduction of PbMoO4 and PbWO4

The phenomenon of the coloration of Czochralski grown single crystals of PbMoO₄ and PbWO₄ is discussed. This coloration is supposed to be related to an intrinsic point defect. We propose that during the crystal growth a loss of oxygen occurs, and consequently, oxygen deficient crystals are produced. The existence of electronic charge carriers at high temperatures and ionic majority defects in the oxygen sublattice is confirmed by conductivity measurements. The color center is supposed to be an oxygen vacancy that has trapped one or two electrons. On the basis of this simple model, various aspects of the coloration can be understood.     

Enantioselective synthesis of bridged bicyclic ring systems

The type 2 intramolecular Diels-Alder (IMDA) reaction is a valuable method for synthesis of both carbocyclic and heterocyclic bridged bicyclo[5.3.1]undecane and bicyclo[4.3.1]decane ring systems. These structures are common to a number of biologically important natural products. Asymmetric variants of the type 2 IMDA reaction incorporating oxazolidinone chiral auxiliaries have been evaluated. This study has resulted in systems that deliver bridged bicyclic [5.3.1] and [4.3.1] ring systems in high diastereomeric (97-99% de) and enantiomeric purity.