Structural stability in discrete singular systems

In this paper,we study the structural stability of singular discrete systems with perturbations in coefficient matrices,Some sufficient and necessary conditions of structurally stable singular discrete systems are given,Two kinds of structurally stable normal compensators are discussed.     

New Cembrane-Type Diterpenoids from the South China Sea Soft Coral Sinularia nanolobata

In the present study,nine new cembrane-type diterpenoids,namely ximaonanolobatins A—I(1—9),together with six related known analogs(10—15)and four known tetraprenylated alkaloids malonganenones D,E,H,and K(16—19)were isolated from the soft coral Sinularia nanolobata collected off the Ximao Island in the South China Sea.The structures of 1—9 were robustly established by a combination of detailed spectroscopic analyses,chemical reactions,quantum mechanical(QM)-NMR methods,biogenetic consideration,and the comparison with those literature data.The absolute configuration of 1 was confirmed by X-ray diffraction analysis,and the absolute configuration of 2 was determined by QM-NMR calculations and chemical transformation.In addition,the absolute configuration of 3 was determined using the modified Mosher's method.All these isolates were evaluated for their anti-inflammatory and anti-tumor activities.The results showed that only compound 15 exhibited potential anti-inflammatory effect against LPS-induced TNF-αrelease in RAW264.7 macrophages with an IC50 value of 12.6μmol/L.     

He离子辐照6H-SiC引入缺陷的光谱研究

实验采用300 keV的He²⁺辐照6H-SiC,辐照温度分别为室温,450,600和750 ℃,辐照剂量范围为1×10¹⁵–1×10¹⁷ cm^-2,辐照完成后对样品进行拉曼散射和紫外可见透射光谱测试与研究. 这两种分析方法的实验结果表明,He离子辐照产生的缺陷以及缺陷的恢复与辐照剂量和辐照温度有着直接关系. 室温下辐照会使晶体出现非晶化,体现在拉曼特征峰消失,相对拉曼强度达到饱和(同时出现了较强的Si-Si峰);高温下辐照伴随着晶体缺陷的恢复过程,当氦泡未存在时,高温辐照很容易导致Frenkel对、缺陷团簇等缺陷恢复,当氦泡存在时,氦泡会抑制缺陷恢复,体现在相对拉曼强度和相对吸收系数曲线斜率的变化趋势上. 本文重点讨论了高温辐照情况下氦泡对缺陷聚集与恢复的影响,并与高温下硅离子辐照碳化硅结果进行了对比. 关键词： 6H-SiC 氦泡 拉曼散射光谱 紫外可见透射光谱     

蒽二酮类化合物的合成及结构-非线性光学性能关系的研究

设计合成了6个新的蒽二酮类化合物,用紫外可见吸收光谱、傅里叶变换红外光谱、1H 核磁共振和元素分析表征了结构.采用飞秒激光,运用简并四波混频法,研究了化合物在非共振状态下的三阶非线性光学性能.它们的三阶非线性光学极化率χ(3)为2.62～3.55×10－13 esu,非线性折射率n2为4.82～6.52×10－12 esu,分子二阶超极化率γ为2.57～3.25×10－31 esu,响应时间τ为91～116 fs.探索了化合物的分子结构对三阶非线性光学性能的影响.增长共轭链,形成供吸供构型,增大取代基的供电子能力,提高共轭体系的共平面程度等因素有利于获得较大的三阶非线性光学性能.     

Click synthesis and dye extraction properties of novel thiacalix[4]arene derivatives with triazolyl and hydrogen bonding groups

Using a click reaction between alkynylthiacalix[4]arene and ethyl 2-azidoacetate followed by an ammonolysis with ethanolamine,leucinol and hydrazine hydrate,respectively,three novel thiacalix [4]arene derivatives 4,5 and 6 with triazolyl and hydrogen bonding groups(NH and OH) were synthesized in high yields.They exhibited excellent extraction capability for six anionic and cationic dyes.The flexible cavity,π-triazole rings and hydrogen bonding groups all play crucial roles in dye complexation.     

Improved hydrostatic pressure sample injection by tilting the microchip towards the disposable miniaturized CE device

A simple method of hydrostatic pressure sample injection towards a disposable microchip CE device was developed. The liquid level in the sample reservoir was higher than that in the sample waste reservoir (SWR) by tilting microchip and hydrostatic pressure was generated, the sample was driven to pass through injection channel into SWR. After sample loading, the microchip was levelled for separation under applied high separation voltage. Effects of tilted angle, initial liquid height and injection duration on electrophoresis were investigated. With enough injection duration, the injection result was little affected by tilted angle and initial liquid heights in the reservoirs. Injection duration for obtaining a stable sample plug was mainly dependent on the tilted angle rather than the initial height of liquid. Experimental results were consistent with theoretical prediction. Fluorescence observation and electrochemical detection of dopamine and catechol were employed to verify the feasibility of tilted microchip hydrostatic pressure injection. Good reproducibility of this injection method was obtained. Because the instrumentation was simplified and no additional hardware was needed in this technology, the proposed method would be potentially useful in disposable devices.     

Components of the heartwood of <Emphasis Type="Italic">Populus euphratica</Emphasis> from an ancient tomb

To probe the organic constituents of over 2000-year-preserved Populus euphratica found in an ancient tomb, a chemical investigation was undertaken, which led to the isolation of a new compound, 2-(4′-hydroxy-3′-methoxyphenyl)-2-oxoacetamide (1), together with 12 known compounds (2–13) by column chromatography. Their structures were elucidated on the basis of spectroscopic evidence. It is the first time that compounds 2–13 were isolated from this plant. Published in Khimiya Prirodnykh Soedinenii, No. 1, pp. 7–9, January–February, 2008.     

Expression of Cu,Zn-superoxide dismutase gene from <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> in <Emphasis Type="Italic">Pichia pastoris</Emphasis> and its resistance to oxidative stress

The gene for the Cu, Zn-superoxide dismutase (SOD) from the yeast Saccharomyces cerevisiae was cloned, characterized, and overexpressed in the methylotrophic Pichia pastoris. The sod gene sequence obtained is 465 bp and encodes 154 amino acid residues. The sod gene sequence was cloned into the pPIC9K vector, yielding pAB22. The linearized pAB22 DNA, digested with restriction enzyme SacI, was transformed into the genome of the GS115 strain of the yeast P. pastoris. The SOD was purified from the cultured yeast by ammonium sulfate precipitation and DEAE-cellulose column chromatography. This relatively simple purification method produced a single band on analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The overexpressed SOD protein was shown to have immunologically biologic activity and to be enzymatically active. The yeast overexpressing Cu, Zn-SOD appeared to be more resistant to oxidative stress such as paraquat, menadione, and heat shock.