A Quantitative Analysis on Avicennia marina Community along Beihai Coast of Guangxi

This paper deals with species diversity,interspecific correlation and populationdistribution pattern of Avicennia marina community along Beihai coast,Guangxi.The results areas follows:(1)The floristic composition and structure of the community are rather simple;(2)Compared with those of terrestrial nature communities,the degrees of interspecificcorrelations of the community are much low;(3)Populations of A.marina and Kandelia candel show random distribution,while Aegicerascorniculatum population is an aggregated distribution.     

A pair of two－component regulatory genes ecrA1／A2 in S. coelicolor

Two-component genes are kinds of genetic elements involved in regulation of antibiotic production in Streptomyces coelicolor. DNA microarray analysis revealed that ecrA1/A2, which mapped at distant sites from red locus and encode respectively the kinase and regulator, expressed coordinately with genes of Red specific biosynthetic pathway, ecrA1 and ecrA2 gene-disruptive mutants were constructed using homogenotisation by reciprocal double crossover. Fermentation data showed that the undecylprodigiosin (Red) level of production was lower than that of wild-type strain. However, the change of the actinorhodin (Act) production level was not significant compared with wild type. Thus, these experiment results confirmed that the two-component system ecrA 1/A2 was positive regulatory element for red gene cluster.     

A CLASS OF SPHERICAL MATRIX DISTRIBUTIONS

The class of distributions on R~m, 1≤m<∞ which are the m-dimensionalmarginal distributions of orthogonally invariant distribution on R~(m n) wascharacterized by Eaton (1981). In this paper, the class of distributions onR~(m×p), 1≤m<∞ which are the m×p marginal distributions of othogonallyinvariant distribution on R~(m n)×p is characterized.     

A new approach to studying ENSO predictability： Conditional nonlinear optimal perturbation

A new approach, the conditional nonlinear optimal perturbation (CNOP) is introduced to study the predictability of El Nifio-Southern Oscillation (ENSO) using a theoretical coupled ocean-atmosphere model. The differences between CNOP and linear singular vector (LSV) are demonstrated. The results suggest that the nonlinear model and CNOP are superior in determining error growth for studying predictability of the ENSO. In particular, the CNOP approach is used to explore the nature of the ‘spring predictability barrier‘ in ENSO prediction.     

A Semantic-based Clustering Method to Build Domain Ontology from Multiple Heterogeneous Knowledge Sources

IntroductionNowadays ,there are a large number of heterogeneousknowledge sources in an enterprise or a VirtualManufacturing Organization( VMO) . For example ,expertsystems , data warehouse , books , manuals , standards ,experts , and so on. Heterogeneity in knowledge sourcesare due to[1 4]:(1) Some are represented explicitly (eg.expert systems) ,some are represented i mplicitly as schemas of database ordata warehouse , while some are stored in experts brains .Implicitly represented knowledg…     

A New—style Permanent—magnet Motor with Double—stator Structure

A new-style direct drive motor with double-stator structure is proposed. The structure and principle of the permanent-magnet (PM) brushless motor are discussed. On the basis of numerical calculation, the cogging torque waveforms of the prototype rrmtor when staggering two stators are analyzed. The method that can reduce torque ripple making use of the structure features of this motor is investigated. The results of numerical calculation and experiment indicate that designing motor with this kind of structure is a good seherne for increasing the power density.     

A New Way of the Skeletal Metals Synthesis

1 Results Strongly disordered metals with the high chemical and catalytic activity are often called as skeletal metals.Usually for their preparation the metallides of d-metal (which afterwards will be left in the "skeleton") and chemically active component(s) are firstly synthesized.Then the last one(s) is (are) removed by the leaching with aqueous solutions of alkalis or carbonates.However,this method sometime fails,first of all,for the reactions,which should be realized in non-aqueous conditions.In the present work a "dry" way of the activated metals making,based on the method of selective vapor transporting reactions (SVTR) has been considered.The main idea of this method is the removal of the active component from a metallide to the vapor phase.For instance:     

EXTENDING POMPEIU OPERATOR AND THE COMPACTNESS OF SOLUTION SET FOR A CLASS OF HIGHER ORDER PARTIAL DIFFERENTIAL EQUATIONS

This paper discusses chiefly the compactness of solution set of following equationswhere △ is the Laplacian in Sobolev's sense, a;(x),i= 0,1,…n, n≥ 3, are real square matrices of dimen-sion N×V , bounded and measurable in a bounded multiply connected domain Ω, the boundary S is as-sumed to be sufficiently smooth, u(x) is unknown vector, z = (x_1,x_2,…,x_n) Ω R~z,m≥1,|S_1|issuperficial measure of the unit sphere of R~Z, |i|=i_1+ i_2 +… + i., △~m=△(△~(m-1)). ,(Ω), ,(Ω), … denote the classes of vectors or matrices whose elements belong to L,(Ω),W,(Ω),…. A vector or a matrix is said to be continuous differentiable, bounded and measurable if so are its ele-     

A NEW GENERATION PHASE-SENSITIVE DETECTOR

A new generation phase-sensitive detector based on a Texas Instruments TMS32010 digital signal processor has been designed and constructed may which be operated as a stand-alone instrument as well as under remote control from a desk-top computer through an IEEE 488 (GPIB) interface. The frequency, gain, bias and attenuation of the instrument are programmable.A 24 character 5×7 dot matrix alphanumeric display system and 16 digit keyboard are used to display the results of the inphase and the quadrature signals, and to change the programmable constants. The instrument is intended for use as a low frequency network analyser.     

Effect of Aβ1-40 on membrane permeability and intracellular free Ca2+ of nerve cells

The effects of soluble and fibrillar Aβ1-40 on membrane permeability and intracellular free Ca^2 of nerve cells were investigated by the laser confocal microscopy. Results indicate that: i) Effects of soluble and fibrillar Aβ1-40 on cell membrane permeability are both concentration-dependent. Soluble Aβ1-40 increases membrane permeability only at concentration of 3μmol/L, while the toxic effect of fibrillar Aβ1-40 is much stronger, its evident effect begins from 1μmol/L. When its concentration rose to 3μmol/L, not only the membrane permeability increased, but also the nuclear membrane broke seriously, ii) Both soluble and fibrillar Aβ1-40 at high concentrations increased the intracellular free Ca^2 , and the increased amplitudes are concentration-dependent. However, the fibrillar one induces the increase of intracellular Ca^2 much quicker and synchronously.These results indicate that some correlation exists between the neurotoxicity of high concentration soluble and fibrillar Aβ1-40 and the change of physico-chemical properties and intracellular Ca ion imbalance.     

聚合物前驱体法合成La0.6Sr0.4Co0.2Fe0.8O3-δ纳米粉体

采用聚合物前驱体法,以硝酸盐为原料,乙二醇为溶剂,甘氨酸为螯合剂制备La0.6Sr0.4Co0.2Fe0.8O3-δ前驱体溶胶及其纳米粉体,考察甘氨酸用量、溶胶蒸发温度及时间对溶胶稳定性的影响。结果表明:当甘氨酸和总金属离子物质的量之比为1∶1时,65℃蒸发48 h可得到均匀、稳定的前驱体溶胶;所得凝胶在700℃下烧结5 h可得到平均粒径为54.4 nm的纯钙钛矿型粉体。     

乙二醇中纳米Ni粉的合成

以乙二醇为溶剂,用还原法制备了纳米Ni粉。实验产物经XRD分析实验证实为粒度约为20nm的面心立方结构的纳米Ni粉。制备过程中反应阶段可以根据颜色变化来推断,纳米颗粒的尺寸与反应物的浓度、催化剂的浓度有直接的关系。在制备的过程中,乙二醇对纳米Ni粉的分散效果很显著。     

铜铟硒纳米粉体的水热合成与表征

以水为溶剂、CuCl2,InCl3和Se粉为反应物、NaBH4为还原剂采用低温水热法在200℃反应18h得到了CuInSe2纳米粉末.用X射线粉末衍射仪、X射线光电子能谱仪、场发射扫描电子显微镜、透射电子显微镜对粉体的结构、形貌、成分进行表征.研究表明:所生成纳米粉末的平均颗粒直径在100nm左右;反应温度和时间对产物的生成和形貌有重要影响,在200℃以上反应有利于获得黄铜矿型CuInSe2纳米粉末的纯相,且产物的尺寸随着反应时间的延长而增大.并对CuInSe2粉体的形成机理进行了简单探讨.     

漂浮阳极泥中铋的提取与三氧化二铋的制备

漂浮阳极泥经过盐酸浸出、稀释水解、氢氧化钠中和得到氯氧铋,氯氧铋经过氢氧化钠转化制备得到三氧化二铋.当盐酸浓度为6mol/L,固液比为1∶5,反应温度为80℃,反应时间为1h时,漂浮阳极泥中锑和铋浸出率分别达到99.17％和99.08％.当稀释比为8∶1时,盐酸浸出液中锑水解率为98.13％,铋水解率仅为8.8％.稀释后液中加入氢氧化钠溶液,当pH为1.5时,铋水解率达到99.5％,水解产物氯氧铋(BiOCl)中铋、氧、氯的质量分数分别为54.23％,19.30％和14.61％.氯氧铋再次经过盐酸浸出,稀释水解,氢氧化钠沉淀得到氯氧铋.除杂后氯氧铋经过硫酸洗涤、氢氧化钠转化,当氢氧化钠浓度为6mol/L,液固比为3∶1,反应温度为80℃时,反应2h后过滤,用0.5mol/L盐酸洗涤得到形貌为纤维状、晶型为单斜的α-Bi2O3,氧化铋纯度达到99.81％.     

Bi2S3纳米棒的可控合成和表征

采用水热法,以Bi(NO3)3·5H2O和Na2S·9H2O为前驱体,通过不同的反应条件合成出不同形貌的Bi2S3纳米棒.所得产物用XRD和TEM进行了分析和表征.结果表明,当Na2S·9H2O与Bi(NO3)3·5H2O的摩尔比为2∶1,水热合成温度为l50℃,前处理模式为超声振荡时,所得Bi2S3纳米棒结晶度较高,...     

牺牲模板法硒化铜纳米管的制备与表征

文章通过牺牲模板法,在80℃的乙二醇中通过一种简易的实验方案实现了内径为50~120 nm、管壁厚为60~100 nm的均匀CuSe纳米管的大量合成。该方案是在溶剂中利用铜纳米线作为牺牲模板与合适的硒源进行反应,适当的硒源、铜纳米线和溶剂在CuSe纳米管的形成中起决定性作用。采用X射线粉末衍射仪(XRD)、透射电子显微镜(TEM)、UV吸收光谱和场发射扫描电镜(SEM)对样品进行了表征。     

正丁醇溶剂热法制备Bi2O2CO3及可见光光催化降解有毒有机污染物

分别以乙醇、异丙醇和正丁醇为溶剂介质,在水热条件下制备得到Bi2O2CO3,考察了不同溶剂介质、水热反应温度和反应时间等因素对制备Bi2O2CO3粉体及其光催化活性的影响,优化了Bi2O2CO3光催化剂的制备条件,结果表明：水热温度为200℃,时间为14h时,以正丁醇为溶剂介质条件下制备的Bi2O2CO3具有高的催化活性,可制得具有较高光催化活性的Bi2O2CO3催化剂．运用XRD、SEM手段对Bi2O2CO3进行了初步表征．在可见光照射（λ≥420nm）条件下,研究光催化降解染料罗丹明B（RhodamineB,RhB）和无色小分子水杨酸（Salicylicacid,SA）溶液在pH-7．0条件下的反应特性,结果显示照射时间180rain对RhB的脱色完全和210min对SA的降解率可达80％以上,同时对RhB矿化率可达80％,表明所建立的光催化体系可有效降解有毒有机污染物．     

一种低温解封阴极电泳漆单组份固化剂的合成与表征

以乙二醇单丁醚为溶剂,己内酰胺为封闭剂对TDI进行封闭,得到单组份固化剂。通过红外测试、热失重测试对得到的单组份固化剂进行表征,探讨了在不同条件下—NCO的封闭率,进而确定最佳实验条件为n(活泼H)∶n(—NCO)为1.2,封闭反应温度控制在90℃左右为宜,反应时间为4 h。     

二氧化钛负载磷钨钼杂多酸催化合成环己酮乙二醇缩酮

采用浸渍法制备了二氧化钛负载磷钨钼杂多酸催化剂H₃PW6Mo₆O₄0/TiO₂, 该催化剂的适宜制备条件为: 原料TiO₂和H₃PW₆Mo₆O₄₀的质量均为1.0 g,水的用量30 mL,浸渍时间12 h,活化温度150 ºC。以H₃PW₆Mo₆O₄₀/TiO₂为催化剂,对以环己酮与乙二醇为原料合成环己酮乙二醇缩酮的反应条件进行了研究,较系统地研究了酮醇物质的量比、催化剂用量、反应时间对收率的影响。实验结果表明,在n（环己酮）∶n(乙二醇)=1.0∶1.5、催化剂用量占反应物料总质量的1.0%、反应时间0.75 h的条件下,环己酮乙二醇缩酮的收率为87.7%。     

液相还原法制备Fe—Cr纳米粉

以三乙基硼氢化钠为还原剂，甲苯为溶剂，聚乙烯吡咯烷酮（ＰＶＰ）为分散剂，以铁、铬混和盐为原料制备出了约５０ｎｍ的Ｆｅ－Ｃｒ粉末。探讨了粉末合成过程的工艺条件及通过低温热处理方法获得了纳米Ｆｅ－Ｃｒ合金粉末。反应中加入的ＰＶＰ高分子分散剂起了改善粉末的形态与团聚程度的作用。