Synthesis and biological activity of alkylidene-substituted cephems and penams

The condensation of tert-butyl esters of 3-methyl-7-oxoceph-3-em-4-carboxylic and 6-oxopenicillanic acids with a series of 2-oxoalkylidene(triphenyl)phosphoranes gave tert-butyl esters of new cephalosporin and penicillin analogs with an alkylidene substituent in the β-lactam ring. Most of these products were oxidized by meta-chloroperbenzoic acid to the corresponding sulfones. The cephemes and penams synthesized including the oxidized products displayed high cytotoxicity relative to cancer cells in vitro. Some of the alkylidene-substituted cephems as the free acids, similar to Tazobactam, inhibit the catalytic activity of Enterobacter cloacae penicillinase.     

微分方程解的存在与惟一性的一种证明

运用Banach压缩定理可证明微分方程解的存在与惟一性.     

人力资源与区域经济发展分析

人力资源是实现区域经济发展的最重要条件之一，从已有的经济理论模型理论研究及本建立经济数学模型实证研究表明，人力资源数量，质量，结构，流动都影响区域经济发展，加快区域经济发展，必须加大教育投入，创造条件吸引人才，加强技术技能培训，增加第三产业作人力资源等。     

再谈应用数学的发展——对“试谈”的补充意见

本文采用校勘的格式对 [1]提出补充意见     

Oximes of five-membered heterocyclic compounds with three and four heteroatoms 2. Synthesis of derivatives,reactions, and biological activity (Review)

Data on the reactions of triazole, tetrazole, dioxazole, oxadiazole, and thiadiazole aldoximes, ketoximes, and amidoximes, their synthesis, and the reactions of their derivatives are reviewed. The synthesis of new heterocycles based on the oximes of five-membered heterocyclic compounds with three and four heteroatoms is examined separately. The principal results from investigation of the biological activity of ethers of these oximes are also presented. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 963–990, July, 2008.     

Quantitative determination of 15 bioactive triterpenoid saponins in different parts of Acanthopanax henryi by HPLC with charged aerosol detection and confirmation by LC–ESI‐TOF‐MS

Triterpenoid saponins are difficult to analyze using high‐performance liquid chromatography coupled to UV/vis spectrophotometry due to their lack of chromophores. This study describes the first analytical method for the determination of 15 triterpenoid saponins from the leaves, stems, root bark, and fruits of Acanthopanax henryi, using a high‐performance liquid chromatography with charged aerosol detection coupled with electrospray ionization mass spectrometry method. The separation was carried out on a Kinetex XB‐C18 column with an acetonitrile/water gradient as the mobile phase, followed by charged aerosol detection. The operating conditions of charged aerosol detection were set at 24 kPa for nitrogen pressure and 100 pA for the detection range. Liquid chromatography with electrospray ionization mass spectrometry is described for the identification of compounds in plant samples. The electrospray ionization mass spectrometry method involved the use of the [M + Na]⁺ and [M + NH₄]⁺ ions for compounds 1 – 15 in the positive ion mode with an extracted ion chromatogram. The developed method was fully validated in terms of linearity, sensitivity, precision, repeatability, and recovery, then subsequently applied to evaluate the quality of A. henryi.     

Technology of preparing anode films and the effect of co-sensitization in dye-sensitized solar cells

Nanocrystalline N–Zn/TiO₂ anode films were prepared by doping element N and Zn. These element-doped films have a better performance in dye-sensitized solar cell than the non-doped film. The test shows that the best thickness of N–Zn/TiO₂ anode film is 13.5 μm. UV–Visible measurements show that there is a complementarity in ultraviolet–visible absorbance range between P3OT and N719, both are used as dyes in this study, the former is prepared and the latter is commercially available. SEM shows a significant mass increase of anode film after treated with TiCl₄. Solar cells based on N–Zn/TiO₂ anode film with TiCl₄ treatment was firstly co-sensitized by N719/P3OT. A solar-to-electric energy conversion efficiency of 3.54 % was obtained. Compared with the traditional dye-sensitized solar cell, the photoelectric conversion efficiency, V _oc and J _sc have been increased.     

Vectors in a box

For an integer d ≥ 1, let τ(d) be the smallest integer with the following property: if v ₁, v ₂, . . . , v _t is a sequence of t ≥ 2 vectors in [?1, 1] ^d with ${{\bf v}_1+{\bf v}_2+\cdots+{\bf v}_t \in [-1,1]^d}$ , then there is a set ${S\subseteq \{1,2,\ldots,t\}}$ of indices, 2 ≤ |S| ≤ τ(d), such that ${\sum_{i \in S}{\bf v}_i \in [-1,1]^d}$ . The quantity τ(d) was introduced by Dash, Fukasawa, and Günlük, who showed that τ(2)?=?2, τ(3)?=?4, and τ(d)?=?Ω(2 ^d ), and asked whether τ(d) is finite for all d. Using the Steinitz lemma, in a quantitative version due to Grinberg and Sevastyanov, we prove an upper bound of τ(d) ≤ d ^d+o(d), and based on a construction of Alon and V?, whose main idea goes back to H?stad, we obtain a lower bound of τ(d) ≥ d ^d/2-o(d). These results contribute to understanding the master equality polyhedron with multiple rows defined by Dash et?al. which is a “universal” polyhedron encoding valid cutting planes for integer programs (this line of research was started by Gomory in the late 1960s). In particular, the upper bound on τ(d) implies a pseudo-polynomial running time for an algorithm of Dash et?al. for integer programming with a fixed number of constraints. The algorithm consists in solving a linear program, and it provides an alternative to a 1981 dynamic programming algorithm of Papadimitriou.     

Glycerol monooleate-blood interactions

In the present study the initial blood compatibility of glycerol monooleate (GMO)-coated surfaces was evaluated after deposition to surfaces and in bulk. The model surface was silica onto which multiple layers of fibrinogen or human serum albumin (HSA) was immobilized. The protein-coated surfaces were subsequently dip-coated in GMO in ethanol and used for blood plasma and whole blood experiments. The characterization methods included null ellipsometry, scanning electron microscopy, imaging of coagulation, hemolysis test and whole blood coagulation time by free oscillation rheometry. The results showed a GMO film thickness of approximately 350 A (approximately 4 microg/cm(2)) upon dip-coating in ethanolic solution. A major part of the deposited layer detached in aqueous solutions, especially during shear conditions. The coagulation time on GMO was significantly prolonged compared to that on HSA coated silica. Whole blood tests showed that GMO is a very weak hemolytic agent. Deposited GMO detached easily from surfaces upon rinsing or shearing, although a stable layer with undefined phase structure and a thickness of 50-70 A remained on HSA and fibrinogen precoated surfaces. This indicates that GMO has stronger adhesive forces to its substrate compared to the cohesive forces acting within the bulk GMO. The ability of GMO to detach from itself and tentatively form micelles or lipid bilayers when subjected to flowing blood may be of use in extravascular applications. It is concluded that GMO results in weak blood activation, and the material may in spite of this be suitable in selected biomaterial applications, especially as a biosealant and in colloidal dispersions.     

2-巯基苯并咪唑衍生物的设计、合成及抗肿瘤活性研究

为了从苯并咪唑类衍生物中寻找新的活性化合物,以溴乙酸作为起始原料,设计合成了17个2-巯基苯并咪唑衍生物4a～4q。采用噻唑蓝(MTT)法测试了目标化合物对人宫颈癌细胞(He La)、人乳腺癌细胞(MCF-7)、人肝癌细胞(HepG2)、人非小细胞肺癌细胞(A549)的增殖抑制活性。结果显示,大部分化合物具有较好的抗肿瘤活性,其中,((1H-苯并[d]咪唑-2-基)硫基)-1-(4-二苯甲基哌嗪-1-基)乙烷-1-酮(4l)对HepG2细胞的抑制活性最好,IC_(50)值为12. 62±0. 78μmol/L,接近于对照药品吉非替尼(9. 72±0. 38μmol/L)。此外,利用分子对接方法对目标化合物的构效关系进行了讨论。