轴对称射流气动声场的数值模拟

构造了Kirchhoff积分和CFD计算相结合的算法，采用高精度差分格式对不同喷口马赫数的轴对称射流进行数值模拟，并以此作为近场声源，运用Kirchhoff积分方法研究远场气动噪声。数值结果表明，远场噪声具有方向性，噪声声压在离开对称轴20℃处达到最大值。随着传播距离增大，噪声方向性逐渐减弱。

Generalized rayleigh principle and its applications

In this paper, we mainly deal with cigenvalue problems of non-self-adjoint operator. To begin with, the generalized Rayleigh variational principle, the idea of which was due to Morse and Feshbach, is examined in detail and proved more strictly in mathematics. Then, other three equivalent formulations of it are presented. While applying them to approximate calculation we find the condition under which the above variational method can be identified as the same with Galerkin's one. After that we illustrate the generalized variational principle by considering the hydrodynamic stability of plane Poiseuille flow and Bénard convection. Finally, the Rayleigh quotient method is extended to the cases of non-self-adjoint matrix in order to determine its strong eigenvalne in linear algebra.

Growth of high quality Cr, Yb codoped gadolinium gallium garnet (Gd3Ga5O12) crystal and its spectral properties

The Cr(0.1%),Yb(10%):GGG crystals have been grown by the Czochralski method. The chemical composition is: Yb0.33Gd2.47Cr0.005Ga5.2O12. There are no observed Yb3+ ions substituting Ga3+ ions, just like that of Yb:GGG crystals. The defects in Cr,Yb:GGG crystal were also investigated. The absorption and emission spectra of Cr,Yb:GGG crystal at room temperature have been measured. The 02 and H-2 annealing effect of Cr,Yb:GGG crystal have been compared. Cr3+ can greatly weak the visible luminescence of this crystal. The Cr-Yb-codoped crystals may be potential materials for compact, efficient, high stability LD pumped solid state lasers. (C) 2006 Elsevier B.V. All rights reserved.

脊胸天牛(Rhytidodera bowringii White)在杧果树枝干的分布研究

本文研究了果树害虫脊胸天牛（ＲｈｙｔｉｄｏｄｅｒａｂｏｗｒｉｎｇｉｉＷｈｉｔｅ）在云南景谷县果国内对果树枝干的分布和危害情况。结果表明，该害虫在三年和象牙树上主要危害３～５年生枝条，其有虫枝率分别为６５．３％和９２．０％。另外，按地形将果园分为上、中、下三个区带，分别调查各区活枝、地面枯枝和腐枝中的害虫。结果显示，中区活枝、枯枝、腐枝的有虫枝率分别为６０．０％，３０．０％和１７．０％，其有虫枝率分别高于果园的上区和下区。总体上看，三个区带活枝、枯枝和腐枝的有虫枝率分别为５６．８％，３４．０％和１４．３％。定期清除果国内的枯枝和腐枝是防治脊胸天牛的有效措施之一。

应用碳、氮稳定同位素研究鄱阳湖枯水末期水生食物网结构

稳定碳、氮同位素比值分析技术是研究生态系统中物质循环与能量流动的有效技术。δ13C值常用来分析消费者食物来源,δ15N值常用来确定生物在食物网中的营养位置。应用稳定同位素技术分析了鄱阳湖北部湖口县、都昌县、星子县、吴城镇4个采样点95条鱼和其他食物网成分样品的碳、氮稳定同位素比值,构建了鄱阳湖枯水期末期水生食物网。结果表明,不同水域颗粒有机物(POM)的δ13C值不同,范围为-27.5‰～-24.6‰可以区分赣江、修水、鄱阳湖、长江和鄱阳湖湖交汇处水体的颗粒有机物特征。江西鄱阳湖国家级自然保护区受人类活动

Molecular characterization and expression profiles in response to bacterial infection of Chinese soft-shelled turtle interleukin-8 (IL-8), the first reptilian chemokine gene

In this study, an IL-8 homologue has been cloned and identified from a reptile, Chinese soft-shelled turtle for the first time. The full-length cDNA of turtle IL-8 was 1188 bp and contained a 312 bp open reading frame (ORF) coding for a protein of 104 amino acids. The chemokine CXC domain, which contained Glu-Leu-Arg (ELR) motif and four cysteine residues, was well conserved in turtle IL-8. The 4924 bp genomic DNA of turtle IL-8 contained four exons and three introns. Phylogenetic analysis showed that the amino acid sequence of turtle IL-8 clustered together with birds. RT-PCR analysis showed that turtle IL-8 mRNA was constitutively expressed liver, spleen, kidney, heart, blood and intestine tissues of control turtles. Real-time quantitative PCR analysis further indicated that the turtle IL-8 mRNA expression was apparent in various tissues at 8 h and up-regulated significantly during 8 h-7 d after Aeromonas hydrophila infection. The present studies will help us to understand the evolution of IL-8 molecule and the inflammatory response mechanism in reptiles. (C) 2009 Elsevier Ltd. All rights reserved.

Environmental signals: Synthetic humic substances act as xeno-estrogen and affect the thyroid system of Xenopus laevis

According to outdated paradigms humic substances (HS) are considered to be refractory or inert that do not directly interact with aquatic organisms. However, they are taken up and induce biotransformation activities and may act as hormone-like substances. In the present study, we tested whether HS can interfere with endocrine regulation in the amphibian Xenopus laevis. In order to exclude contamination with phyto-hormones, which may occur in environmental isolates, the artificial HS 1500 was applied. The in vivo results showed that HS 1500 causes significant estrogenic effects on X. laevis during its larval development and results of semi-quantitative RT-PCR revealed a marked increase of the estrogenic biomarker estrogen receptor mRNA (ER-mRNA). Furthermore, preliminary RT-PCR results showed that the thyroid-stimulating hormone (TSH beta-mRNA) is enhanced after exposure to HS1500, indicating a weak adverse effect on T3/T4 availability. Hence, HS may have estrogenic and anti-thyroidal effects on aquatic animals, and therefore may influence the structure of aquatic communities and they may be considered environmental signaling chemicals. (c) 2005 Elsevier Ltd. All rights reserved.