New Aspects of Cyclodextrin Chemistry Induced by Outside Type Complex Formation; Asymmetric Reduction of Indol-3-Pyruvic Acid with NaBH4 in Aqueous Solution

Asymmetric reduction of indol-3-pyruvic acid (IPA) with NaBH₄ in aqueous solution in the presence of various cyclodextrins (α-, β-, γ-, mono-6-amino-6-deoxy-β- and di-6^ABamino-6^AB-deoxy-β-cyclodextrin) was investigated. From the NMR and circular dichroism spectral studies, the conformation of the CyD–substrate complexes is suggested; the part of carboxylic group stay in the cavity of α-CyD, whole of IPA in β-CyD, two molecules in a γ-CyD cavity, and IPA(s) is/are on the rim of the cavity of mono-6-amino-6-deoxy-β- and di-6^ABamino-6^AB-deoxy-β-CyD (AβCyD, DAβCyD) with electrostatic interaction between amino group and carboxylic group. This conformational difference provides in the difference in the optical selectivity of reduction.     

Ribbon tile invariants

Let be a finite set of tiles, and a set of regions tileable by . We introduce a tile counting group as a group of all linear relations for the number of times each tile can occur in a tiling of a region . We compute the tile counting group for a large set of ribbon tiles, also known as rim hooks, in a context of representation theory of the symmetric group.

The tile counting group is presented by its set of generators, which consists of certain new tile invariants. In a special case these invariants generalize the Conway-Lagarias invariant for tromino tilings and a height invariant which is related to computation of characters of the symmetric group.

The heart of the proof is the known bijection between rim hook tableaux and certain standard skew Young tableaux. We also discuss signed tilings by the ribbon tiles and apply our results to the tileability problem.

     

中国主要滨海油田分布区的生态环境特征及保护对策——以环渤海油田区为例

环渤海地区是我国滨海油田的主要分布区,同时也是典型的生态脆弱区。多年来高强度的石油开采严重破坏了当地生态环境,油田企业虽采取了许多环境治理措施,但生态环境并未出现好转的趋势。本文概述了我国环渤海地区的生态环境特征和油田开发历史,分析了油田开发对生态环境的影响,阐述了油田现行污染物的治理措施,提出了滨海油田区环境的综合治理对策,以资借鉴。     

铝合金轮圈压铸充型凝固过程模拟分析

针对铝合金的压铸工艺特点和充型凝固过程的不透明性,采用华铸CAE软件对铸件进行模流分析,预测铝合金轮圈压铸缺陷位置,优化模具结构设计.模拟结果显示,采用双流道充型平稳,温度场分布均匀,具有较少的气体夹杂和冷隔等倾向,压铸件整体质量较高.     

中国三大经济圈上市民企财务绩效比较研究

通过建立财务绩效综合评价的模型,选取我国三大经济圈97家上市民营企业,根据2004年～2006年的年度报告资料,采用因子分析法对各企业的财务绩效进行横向与纵向的比较研究,分析各地区上市民营企业财务绩效的绩效差异及变化趋势,找出三大经济圈上市民企财务绩效差异的原因,并给出相关建议.     

大肠癌中MTA1和nm23 - H1蛋白的表达及其意义

目的：探讨大肠癌中MTA1、nm23-H1蛋白的表达及其意义。方法：用免疫组化留法检测84例大肠癌MTA1、nm23-H1蛋白的表达。结果：84例大肠癌中MTA1、nm23-H1阳性表达率分别为61．9％和51．2％;MTA1高表达与大肠癌组织分化程度、Duke’s分期和淋巴结转移关系密切（P〈0．05）;nm23-H1低表达与大肠癌组织分化程度、Duke’s分期和淋巴结转移关系密切（P〈0．05）;大肠癌中MTA1和nm23-H1蛋白表达呈负相关（P〈0．05）。结论：MTA1和nm23-H1蛋白表达与大肠癌分化程度、淋巴结转移和预后密切相关,可作为判断大肠癌患者转移复发的参考指标。     

轮缘半径对月球车鼓形轮原地转向阻力矩影响分析

为了给月球车的车轮构型设计、运动控制、模拟仿真等提供理论参考,基于地面力学理论,提出鼓形车轮下陷量判断方法,研究了其转向时轮-地接触的剪切特性与推土特性,并建立鼓形车轮原地转向的力学模型.理论分析表明:转向阻力矩随轮缘半径的增加而呈渐近线性增加.轮缘半径越小,车轮的转向阻力矩越小,使鼓形车轮较圆柱车轮具有更好的转向灵活性.利用月球车车轮运动性能测试系统对2种轮缘半径的车轮进行了原地转向实验,实验结果表明了该理论模型的正确性.     

环渤海地区云量的动力过程相似预报方法

利用环渤海35个台站1954-2002年近50年逐日平均总云量和低云量的观测资料,统计关注区域内少云、中等云量、多云的发生情况;再用同期NCEP再分析资料,计算出预报关注区域内与不同云量形成相关性较好的各种不同要素的平均场,依据动力过程相似原理,利用T213数值预报产品相邻24h预报场,以域块距离为依据,建立云量预报模型,制作日平均总云量和低云量4～9天的预报.经过2003-2007年的预报结果与实况资料的对比检验表明:依据动力过程相似方法建立的云量预报模型对日平均总云量和日平均低云量的预报准确率较高;日平均低云量预报准确率要高于日平均总云量;冬半年预报准确率高于夏半年;天空出现少云的预报准确率高于中等云量和多云的情况.     

热轧汽车轮辋钢孔型设计

通过多年生产实践和大量数据分析,针对热轧汽车轮辋钢的变形特点,研究热轧汽车轮辋钢孔型设计的基本原则和主要参数,总结出该类特异型钢孔型设计的系统设计方法和一些变形规律,对同行在轮辋钢的孔型设计上有所借鉴,以适应轮辋钢的生产需要。     

Formation of upper rim acylated calix[4]arenes using a sacrificial zinc anode

A straightforward electrosynthetic method is described, which allows upper rim acylation of non-p-halogenated calix[4]arenes. For example, a solution of tetrapropoxycalix[4]arene 4 was electrolysed in the presence of ZnBr₂ in an undivided cell fitted with a sacrificial zinc anode using pure acetonitrile as solvent, yielding an organozinc species, which was then treated with acetyl chloride in the presence of a palladium catalyst to afford 5,11-diacetyl-25,26,27,28-tetrapropoxycalix[4]arene 5 in ca. 35% yield after workup.