cis,cis,cis‐Tetra­methyl 1,2,4,5‐cyclo­hexane­tetra­carboxyl­ate

The title compound, C₁₄H₂₀O₈, was synthesized from the hydrogenation of tetra­methyl 1,4‐cyclo­hexa­diene‐1,2,4,5‐tetra­carboxyl­ate with a catalytic amount of palladium/carbon. All four carbonyl moieties of the methyl ester groups are on the same face of the chair‐conformed ring. The substantial ring distortion associated with the 1,3‐diaxial methoxycarbonyl substituents is reflected in the large difference between bond angles as well as torsion angles, respectively, that in undistorted cyclo­hexanes would be approximately the same.     

静动干涉流动的分离涡模拟研究

本文基于一种并行高精度的静动交接面处理方法,采用了SA模型及基于SA的分离涡模拟DES方法,进行了某压气机静动干涉流动的计算.研究表明对本文算例,在微小分离处,如20%到80%叶高处,DES与SA计算出的流动损失相差很小;而在大分离处,如叶根叶顶处,DES结果与SA差别较大,并且DES可更好地描述涡结构.在叶顶处,DES计算出比SA更强的泄漏流动,导致更大的损失.在叶根处,DES计算出了明显的静叶动态尾迹涡脱落现象,这一现象导致了与SA不一样的损失机理,即脱落涡与动叶头部相撞而产生时序效应,从而使计算损失较小.同时,本文研究结果与之前对孤立静叶的研究是相互验证的.     

COMPREHENSIVE MATHEMATICAL MODEL OF MICROCIRCULATORY DYNAMICS(Ⅱ)—ALCULATION AND THE RESULTS

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｃｏｍｐｒｅｈｅｎｓｉｖｅｍａｔｈｅｍａｔｉｃａｌｍｏｄｅｌｄｅｖｅｌｏｐｅｄｉｎｔｈｅｆｉｒｓｔｐａｒｔｏｆｔｈｉｓｐａｐｅｒ[1]ｃｏｎｔａｉｎｓｄｏｚｅｎｓｏｆｃｏｕｐｌｅｄｅｑｕａｔｉｏｎｓｔｈａｔｆｏｒｍａｌａｒｇｅｎｏｎｌｉｎｅａｒｅｑｕａｔｉｏｎｓｙｓｔｅｍ.Ｈｅｒｅｗｅｃｏｍｂｉｎｅａｎａｌｙｔｉｃａｌａｎｄｎｕｍｅｒｉｃａｌｍｅｔｈｏｄｓｔｏｓｏｌｖｅｉｔａｎｄｄｉｓｃｕｓｓａｎｄａｎａｌｙｚｅｓｏｍｅｉｍｐｏｒｔａｎｔｐｒｏｂｌｅｍｓｉｎｍｉｃｒｏｃ…     

A Mann type iterative scheme for variational inequalities in noncompact subsets of Banach spaces

In this paper, we study the existence of solutions and approximation of the solutions by using a Mann type iterative scheme for variational inequalities in noncompact subsets of Banach spaces. The results presented in this paper generalize the corresponding results of J. Li [J. Li, On the existence of solutions of variational inequalities in Banach spaces, J. Math. Anal. Appl. 295 (2004) 115-126].     

Zeros of univariate interval polynomials

Polynomials with perturbed coefficients, which can be regarded as interval polynomials, are very common in the area of scientific computing due to floating point operations in a computer environment. In this paper, the zeros of interval polynomials are investigated. We show that, for a degree n interval polynomial, the number of interval zeros is at most n and the number of complex block zeros is exactly n if multiplicities are counted. The boundaries of complex block zeros on a complex plane are analyzed. Numeric algorithms to bound interval zeros and complex block zeros are presented.     

同时测定三辛胺和三辛胺盐酸盐的双波长分光光度法

提出了利用双波长分光光度法测定三辛胺（ＴＯＡ）及三辛胺盐酸盐（ＴＯＡ·ＨＣｌ）的一种新方法，即ＴＯＡ和ＴＯＡ·ＨＣｌ在ＣＣｌ４溶液中与Ｉ２生成电荷转移化合物，其最大吸收波长分别为２９３ｎｍ和２６３ｎｍ，两组分同时存在时可利用吸光度的加和性得联立方程，分别求出两组分的含量。ＴＯＡ含量在０～３５ｍｇ／Ｌ，ＴＯＡ·ＨＣｌ含量在０～３１ｍｇ／Ｌ范围内符合比耳定律。该法简便快速，方法的回收率为９５．５％～１０４．６％，能够满足分析的需要     

Structures and Absolute Configurations of Three 7,8‐Secolabdane Diterpenes from the Chinese Liverwort Pallavicinia ambigua

The known 7,8‐secolabdane type diterpenoids neopallavicinin ( 1 ), pallavicinin ( 2 ), and 18‐hydroxypallavicinin ( 3 ) were isolated from Pallavicinia ambigua, and their structures were determined. The X‐ray crystal structure of 1 was solved, and, in combination with CD and NMR studies, the absolute configurations of 1 – 3 were established. A possible biogenetic pathway for 1 and 2 from a single labdane precursor is proposed.     

Cleavage of polystyrene‐b‐poly(ethylene oxide) block copolymers with a trithiocarbonate linkage in solutions

In this work, the polystyrene‐b‐poly(ethylene oxide) (PS‐b‐PEO) block copolymers with a trithiocarbonate group between the blocks were prepared by polymerization of styrene in the presence of a trithiocarbonate reversible addition fragmentation chain transfer (RAFT) agent connected with PEO. Decomposition of the trithiocarbonate group by UV irradiation was investigated in three different types of solvent: tetrahydrofuran (THF, common solvent for both blocks), cyclohexane/dioxane mixture (selective solvent for the PS block) and N,N‐dimethylformamide (DMF)/ethanol mixture (selective solvent for the PEO block). It is found that cleavage of the block copolymers can take place in all these three solvents and the cleavage ratio ranges from 76 to 86%. The micellar morphologies in selective solvents before and after cleavage were examined. It is observed that the size of the micelles is reduced after cleavage and sometimes aggregation of the micelles occurs due to removal of the corona of micelles. It shows that this work provides a facile and general method for synthesis of cleavable block copolymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3834–3840, 2010     

MULTIAXIAL BEHAVIOR OF NANOPOROUS SINGLE CRYSTAL COPPER： A MOLECULAR DYNAMICS STUDY

The stress-strain behavior and copper are studied by the molecular dynamics incipient yield surface of nanoporous single crystal （MD） method. The problem is modeled by a periodic unit cell subject to multi-axial loading. The loading induced defect evolution is explored. The incipient yield surfaces are found to be tension-compression asymmetric. For a given void volume fraction, apparent size effects in the yield surface are predicted： the smaller behaves stronger. The evolution pattern of defects （i.e., dislocation and stacking faults） is insensitive to the model size and void volume fraction. However, it is loading path dependent. Squared prismatic dislocation loops dominate the incipient yielding under hydrostatic tension while stacking-faults are the primary defects for hydrostatic compression and uniaxial tension/compression.