基于质量均匀分布的新型MTMD设计模型

提出了刚度和阻尼保持常量但质量均匀分布的新型MTMD设计模型以控制基底加速度激励下结构的振动，结构用某一受控振型的降阶模型表示.利用数值优化技术，研究了MTMD的最优参数，讨论了它对MTMD有效性和鲁棒性的影响.MTMD参数包括：质量间隔、频率间隔、平均阻尼比、调谐频率比、总质量比和总数.MTMD的优化准则定义为结构最大动力放大系数的最小值的最小化.为进行比较，还考虑了刚度和阻尼保持常量但频率均匀分布的MTMD设计模型.数值分析表明，新型MTMD设计模型不存在近0最优平均阻尼比，而且这种新型MTMD设计模型和频率均匀分布的MTMD设计模型达到近似同样的有效性和鲁棒性.     

The involvement of the renin-angiotensin system in the regulation of cell proliferation in the rat endometrium

Oestrogens are known to enhance angiotensin biosynthesis by increasing the elaboration of its precursor, angiotensinogen. On the other hand, we found that inhibition of angiotensin-converting enzyme (ACE) suppressed the proliferative response of the rat anterior pituitary gland to oestrogens. To answer the question whether the angiotensin system is involved in the control of the cell proliferation of the uterine epithelium, the effects of an ACE inhibitor, enalapril maleate, and of angiotensins II and IV, alone or together with losartan, an antagonist of angiotensin receptor type 1 (AT1), on endometrial epithelial cell proliferation have been studied. The experiments were performed on ovariectomized female Wistar rats. In the first experiment the animals were injected with a single dose of oestradiol benzoate or received an injection of solvent only. Half of the oestrogen-treated rats were injected additionally with enalapril maleate (EN, twice daily). The incorporation of bromodeoxyuridine (BrDU) into endometrial cell nuclei was used as an index of cell proliferation. It was found that oestradiol alone dramatically increased the BrDU labelling index (LI) of endometrial cell nuclei, and this effect was partially blocked by the simultaneous treatment with EN. In the second experiment, the animals were injected intraperitoneally with angiotensin II (AII), angiotensin IV (AIV) or saline, alone or together with losartan. It was found that AIV induced an increase in the LI in uterine epithelium, and this effect was not blocked by the simultaneous treatment with losartan. The increase in LI in uterine epithelium was also observed in the rats treated with AII and with losartan. These findings suggest an involvement of angiotensin IV in the control of uterine epithelium cell proliferation. Received 12 October 1998; received after revision 6 January 1999; accepted 2 February 1999     

Formation of the inclusion complex of Orange II with β-Cyclodextrin and its photostability

Inclusion complex of Orange II with β-Cyclodextrin (β-CD) and the anti-photolysis effect under UV-light were investigated. The molar ratio of inclusion complex of β-Cyclodextrin and Orange II is 1∶1. The formation constantK = 1.236×10³ L/mol was determined by the UV and Fluorescence spectra respectively, which was quite in accordance with the calculation with a modified Benesi-Hildbrand equation. The inclusion complex was characterized by the IR spectra and the molar ratio of inclusion complex is 1∶1 too. The formation constantK = 1.266×10³ L/mol was determined by¹H NMR analysis and was nearly the same by UV and fluorescence spectra. The photocatalytic decolorization rate of Orange II solutions containing β-CD and TiO₂ was smaller by 51.9% than that of the Orange II solutions only containing TiO₂, while in the case of direct photolysis of Orange II solutions, β-CD can lower the photolysis rate by 48.1% under UV-light. This result indicates β-CD can inhibit the photolysis and photocatalytic decolorization of Orange II under UV-light. The β-CD inclusion complex was found to be persistent to UV-light photolysis. Foundation item: Supported by the National Natural Science Foundation of China (20177017) Biography: Lu Ping (1958), male. Associate professor, research direction: environmental photochemistry.     

大草履虫总DNA的提取方法比较

快速而稳定地提取大草履虫的基因组DNA是进行后续分子生物学研究的前提.文章通过比较传统SDS法、CTABⅠ法和CTABⅡ法等提取大草履虫DNA的效果,进一步优化提取方法,获得快速稳定地提取大草履虫基因组DNA的方法.结果表明:用CTAB I法提取的DNA浓度低,杂质较多;CTABII提取的DNA电泳时检测不出条带;而SDS法提取的DNA在电泳时带型较整齐,无降解,且DNA的得率和纯度较高,但仍有蛋白质污染.针对蛋白质的去除,用SDS-蛋白酶K法和SDS-NaAc法来提取DNA,经过试验发现这2种方法都能够很好地去除蛋白质,所获DNA样品的纯度和得率都能用于进一步分子试验,而SDS-NaAc法更经济适用.     

利用Mn(Ⅱ)一V(Ⅴ)—DASTM—吐温—80体系催化动力学光度法测定痕量锰(Ⅱ)

在非离子表面活性剂吐温—80存在下,以磷酸为介质,锰(Ⅱ)对钒(Ⅴ)氧化二安替比林苯乙烯甲烷(DASTM)成红色化合物的反应具有较强的催化作用,据此建立了催化光度法测定痕量锰的新方法。该方法的检出限为0.02ngMn(Ⅱ)/ml;线性范围为0—0.15μgMn(Ⅱ)/25ml,对0.1μgMn(Ⅱ)/25ml进行11次测定的相对标准偏差为3.2％。 将本方法用于水样及人发中痕量锰测定,结果令人满意。     

New structure model of oxygen-evolving center and mechanism for oxygen evolution in photosynthesis

So far, many important questions and problems concerning the structure and mechanism of photosynthetic oxygen evolution are still unsolved. On the basis of recent achievements in this field, a new structure model is proposed whereby two H2O molecules bind asymmetrically to two manganese ions (Mn1Ⅱ and Mn4Ⅲ) at the open end of "C" shaped cluster and keep rather large distance. Two histidine residues coordinate to the other two manganese ions in higher oxidation state (Mn2Ⅳ and Mn3Ⅳ ) through their nitrogen atoms of the imidazole. Cl bound as terminal ligand to Mn4Ⅲl is connected to Ca, and the latter is needed to maintain the special configuration of two Mn2O2 units by bridged-oxo and bridged-carboxylate ligands. The whole structure of oxygen evolution center is asymmetry. A new mechanism for oxygen evolution invokes predictions of asymmetric oxidation of two H2O molecules, dynamic structural changes of oxygen e-volving center and indirect proton transport, etc. Only in S2 state, could Mn1Ⅳ = O. intermediate with high oxidation potential be formed. The S2→S3 process occurs with significant structural changes, as well as intramolecular and intermolecular hydrogen transfer. The S3 state corresponds to intermediate of Mn1Ⅳ-O… H… O-Mn4Ⅳ . During S3→ [S4] →S0, the O-O bond is formed only in S4 state. The change of nucleophilic interaction between Cl and manganese ions different oxidation states has consequence for the significant structural changes in H2O oxidation process.     

混合寿命模型下的贝叶斯密度估计(英)

基于一类异族分布的混合寿命模型, 给出了在一/二组样本下的I/II型截尾试验下的贝叶斯密度估计方法; 给出了实例; 并提出了一些问题和解决方法.     

席夫碱型钯(II)配合物液晶的合成与表征

合成了带有端烯基的席夫碱型配体 (Schiff_C11C10 )及其含氯桥型的钯 (II)配合物 (Schiff_C11C10 _Pd) ,通过元素分析 ,摩尔电导 ,红外光谱 ,电子光谱 ,核磁共振等进行了表征 .配合物为中性配合物 ,配体与Pd(II)的摩尔比为 1∶1.配体和配合物均为热致型液晶 .配体和配合物介晶相皆为近晶相 ,配体的液晶态初步判定为镶嵌状织构 ,配合物的液晶态为破扇状织构 .     

Conformational analysis on anti-HIV-1 peptide T22([Tyr5,12,Lys7]-polyphemusinⅡ )

The conformational scan of anti-HIV peptide T22 ([Tyrsup>5,12, Lys⁷]-polyphemusinⅡ) backbone on a deformed potential energy surface (PES) was performed using the potential smoothing searching (PSS) protocol. All located minima were then transferred to the original PES using undeformed optimized potentials for liquid simulations (OPLS) potential function, and minimized by multi-conformer minimization (MCM). For solution-phase calculations, the GB/SA continuum model for water was used. This application of PSS integrated with MCM is proved a feasible method for solving the multiple-minimum problem in the conformational analysis of flexible molecules with cyclic structure.     

正丙醇-氯化钠-硫氰酸铵体系萃取分离Pd(Ⅱ)

研究了氯化钠存在下,正丙醇-硫氰酸铵体系萃取分离Pd(II)的行为.实验结果表明,Pd(II)与SCN-形成的Pd(SCN)42-很容易被萃取到正丙醇相中,当溶液中氯化钠、硫氰酸铵和正丙醇的浓度分别为0.20 kg.L-1、5.0×10-4mol.L-1、0.30 L.L-1,pH 2.5时,能使Pd(II)的萃取率达到99.5%以上,而Cd(II)、Cr(III)、Ni(II)、Al(III)、Fe(II)和Ga(III)等离子基本不被萃取,实现了Pd(II)与上述离子的分离.