Crystal and Molecular Structures of Two Derivatives of 1, 3a, 5-Trisubstituted-3a ,4,5,11-Tetrahydro-1,2,4-Oxadiazolino[5,4-d] [1, 5]Benzothiazepine

The structures of two derivatives of the title compound [C24H22N2OS, Mr = 386. 5 for (1); C25H22N2O3S, Mr = 430. 5 for (2)] were determined by using X-ray single-crystal strcuture analysis method. The final discrepancies are R = 0. 071 and 0. 077, respectively, for the reflections measured on a four-circle diffractometer. The space group for compound (1) is P bca with a=1. 6639(4), b=2.0286(3), c= 1.1742(1) nm, V = 3. 964(1) nm3, F(000) = 1632 e, Z=8; and (2) belongs to P21/n space group, and the cell dimensions are a=1. 1115(4), b=0. 8932(7), c=2. 186(3) nm, β=97. 52 (1)°? V=2.151(4) nm3, F(000) = 904 e, Z=4.The molecular backbones are very similar, each is a tricyclic system. The central seven-membered ring is in a twisted-boat conformation, and is cis-fused to 1,2,4-oxa-diazolino ring, while the latter moiety is in an envelope form. There are conjugated but non-coplanar effects in each structure. All bond lengths and angles in the molecules are normally acceptable. The crystal structure on the whol     

新型聚丙烯酸酯类柴油降凝剂分子模型的建立及验证

在前期工作得出的正构烷烃含量与浊点、冷滤点、凝点的定量关系模型基础上，选择柴油降凝剂的基团对柴油降凝剂分子结构进行了设计，得出了设计模型。结果表明，将含氮基团引入柴油降凝剂可以显著提高柴油降凝剂的性能。根据设计模型合成了一系列聚丙烯酸单酯和混合酯柴油降凝剂，并通过对柴油降凝剂的性能测试结果和自行设计的计算程序对设计模型进行了验证，结果表明，从柴油正构烷烃含量对柴油降凝剂的配比进行设计是可行的。     

热定型聚酯纤维内应力与晶格变形的关系

<正> 结晶学家认为低分子物结晶虽可能存在一定缺陷和变形,但一般都具有一定的晶胞参数。这一概念对于高分子物结晶已不再正确。Bosley认为成形、热处理、冷却速率和杂质的存在皆可引起晶格变形;Fakirov故意在PET中加入少量杂质,却未引起变形。至今,PET已累积了7组晶胞参数,8个计算所得的晶区密度显示了较大幅度的波动(见     

含吩噻嗪金属配合物的合成及非线性光学性质研究

本文报道了一种新的配体:10-乙基-3-甲酰吩噻嗪缩肼基二硫代甲酸甲酯(HL)及其金属配合物的合成。采用了元素分析、质谱、核磁共振、红外光谱对配体及其金属配合物进行了表征。此外,并应用紫外、荧光和Z-扫描技术,测定了配体及其金属配合物的荧光最佳发射波长(λ_max^em)、荧光量子产率(Φ_f)、寿命(τ)和非线性光学性质。结果表明它们在DMF溶液中都能发射出较强的橄榄色荧光,配体及其金属配合物都有双光子吸收,并且金属配合物的非线性光学效应比配体明显增强。用半经验量子化学方法(RHF/PM3)计算结果与实验值较为吻合。     

反对数微分简易示波伏安法的研究

在获得微分简易地波伏安图的实验线路中,增加了反对数装置,提出了反对数微分简易示波伏安法。该方法被应用于铝合金中微量铜和分子筛中微量钴的测定,获得了满意结果。     

POLYMER-PLATINUM COMPLEX CATALYSTS FOR OXIDATION OF METHANOL TO FORMALDEHYDE

Two kinds of polymer-platinum complexes: silica-supported poly-γ-diphenylphosphinopropylsiloxane-platinum complex and silica-supported polyphenylsilazane-platinum complex, have been found very active and selective in catalyzation of oxidation of methanol to formaldehyde at room temperature and under an atmospheric oxygen pressure. Their catalytic activities are greatly affected by P or N/Pt gram atomic ratio.     

RECOGNITION SEQUENCE SPECIFICITY OF SIGNAL PEPTIDASE I AND THE ROLE OF SIGNAL PEPTIDE IN SECRETION OF PROTEIN IN Bacillus subtilis

By recombinant DNA technology, the N-terminal of the β-protein encoding region of plasmid pUBHO is fused with the structure gene of α-amylase from Bacillus licheniformis. This gene fusion is called βAmy. It is able to transcribe and translate in phase. Protein fusion can be secreted into the medium mediated by β-signal peptide. The efficiency of secretion is about 10% of the synthesized pre-α-amylase. By comparing the secretion capacities and analysing the restriction sites on β-Amy genes and the molecular weights of the mature α-amylase secreted by B. subtilis harbouring different plasmids, it is indicated in vivo that the recognition and cleavage sequence for signal peptidase I of B. subtilis is Ala-Ala-Ala Ala. The results also indicate that the secretion of the α-amylase in B. subtilis is in accordance with the post-translational transportation mode.     

泡沫铅对VRLA电池负极活性物质结构及性能影响

0引言随着36V/42V汽车电源系统的提出,新一轮汽车用电池的竞争不断加剧。从目前情况看,铅酸电池由于具有成本低廉,使用可靠,原材料来源丰富,铅回收率可高达98%等优点,因此成为电动车电源最实际的选择之一[1]。但作为电动车用电池,需要克服其比能量低、充电接受能力差和负极硫酸盐化等缺点。为此各国科学家开展了大量的研究工作。最近报道用铸造多孔体作为敞口铅酸电池的集流体,它的比表面积为14cm2·cm-3,正极活性物质利用率上升到50%,远高于传统的铸造板栅[2]。在铅酸电池集流体研究领域里另一个重大进步,就是以R V C(R etic-ulated V i…     

全氟辛基磺酸酸度函数H0的测定

It is reported in this paper that the acidity function H_0 of perfluorooctanesulfonic acid (POSA) is -12.11±0.03, which was measured first time by ~1H NMR method, in term of the α-H chemical shifts of the acid-ether systems, using 98% to 100% H_2SO_4 as reference standards. This method provides a new procedure for measuring the H_0 value of solid perfluoroalkanesulfonie acid C_nH_(2n+1)SO_3H(n>7).     

滂胺天蓝-氨基糖苷类抗生素的显色反应及其分析应用

在 pH2.0～7.0的条件下 ,滂胺天蓝(PSB)与硫酸卡那霉素(KANA)、硫酸庆大霉素(GEN)和硫酸新霉素(NEO)等氨基糖苷类抗生素反应生成蓝色离子缔合物 ,最大显色波长位于686～690nm ,线性范围分别为0～14.0、0～12.5、0～14.0mg/L ,摩尔吸光系数(ε)分别为1.53×104、1.12×104、1.47×104L/(mol·cm) ;最大褪色波长位于620～622nm ,线性范围分别为0～14.0、0～12.0、0～14.0mg/L ,摩尔吸光系数(ε)分别为1.41×104、1.43×104、2.42×104L/(mol·cm) ;当用双波长叠加法测定时 ,ε值分别为2.94×104、2.55×104、3.89×104L/(mol·cm) ;探讨了适宜的反应条件 ;该法用于市售药物中氨基糖苷类抗生素含量的测定 ,结果令人满意