Coherent spectroscopy of the Rb-87 Fg=1 -> F-e=0 closed transition

This paper has observed linewidth narrowing of dark states in rubidium cell by using the Hanle configuration. The reduction of the coherent resonance width under the transition of Rb-87 F-g = 1 -> F-e = 0 is observed and the qualitative explanation about its mechanism is presented. Multiple subnatural width dips are obtained with a linearly polarized laser beam for the transition of Rb-87 F-g = 0, 1, 2. The feature of negative and positive slope, namely dispersionlike feature, is observed in the transmitted light.

部分重力条件下气液两相流型研究

本文分析了"和平号"空间站气液两相流实验中获得的部分重力(0.1 g和0.014 g)条件下的流型特征及其相互转换条件,并将其和常重力与微重力两相流研究中较常用的流型转换模型的预测结果进行了比较.

Influence of low-gravity level on crystal-growth in floating-zone

The influence of low gravity level on crystal growth in the floating zone, which involves thermocapillary convection, phase change convection, thermal and solutal diffusion, is investigated numerically by a finite element method for the silicon crystal growth process. The velocity, temperature, concentration fields and phase change interfaces depending on heating temperature and growth rates are analyzed. The influence of low gravity level on the concentration is studied especially. The results show that the non-uniformities of concentration are about 10(-3) for growth rate nu(p) = 5.12 x 10(-8) m/s, 10(-2) for nu(p) = 5.12 x 10(-7) m/s and relatively larger for larger growth rate in the gravity level g = 0-9.8 m/s2. The thermocapillary effect is strong in comparison with the Bridgman system, and the level of low gravity is relatively insensitive for lower growth rates.

CASTEP软件在正极材料LiFePO_4中的应用

基于第一性原理局域密度泛函(DFT)方法的CASTEP软件包可以计算材料的电子结构,预测和设计新型材料。选择第一性原理赝势法,应用该软件对锂离子电池正极材料LiFePO4进行了两种不同情况下的电子结构计算。结果显示不考虑自旋极化时带隙为0.509eV,而考虑自旋极化时在G点为0.321eV。

Influence Of Gravity On Structure Of Colloidal Crystal Using Simulated Microgravity

Liquid mixtures of water and deuterium oxide as the liquid phase, were used to match the density of charged colloidal particles. Kossel diffraction method was used to detect the crystal structures. The experiments under the density-matched (g=0) and unmatched (g=1) conditions are compared to examine the influence of gravity on the crystal structures formed by self-assembly of 110 nm (in diameter) polystyrene microspheres. The result shows that die gravity tends to make the lattice constants of colloidal crystals smaller at lower positions, which indicates that the effect of gravity should be taken into account in the study of the colloidal crystals.

Synthesis and magnetic properties of Ni-doped zinc oxide powders

Polycrystalline Zn1-xNixO diluted magnetic semiconductors have been successfully synthesized by an auto-combustion method. X-ray diffraction measurements indicated that the 5 at% Ni-cloped ZnO had the pure wurtzite structure. Refinements of cell parameters from powder diffraction data revealed that the cell parameters of Zn0.95Ni0.05O were a little bit larger than ZnO. Transmission electron microscopy observation showed that the as-synthesized powders were of the size similar to 60 nm. Magnetic investigations showed that the nanocystalline Zn0.95Ni0.05O possessed room temperature ferromagnetisin with the saturation magnetic moment of 0.1 emu/g (0.29 mu(B)/Ni2+). (c) 2005 Elsevier B.V. All rights reserved.

桃胶多糖的化学研究及其应用

毛桃(Prunus persica (L.) Batsch)是我国普遍裁培的一种果树。在桃树致病或受伤处会有桃胶(Peach gum)分泌。在一般情况下，天然桃胶是很难溶于水的，因此限制了它的使用。本文首次通过碱溶后，以快速沉淀的方法来降低桃胶的局部结晶度，使得桃胶能较顺利地溶解于冷水中。并提出了由于桃胶对金属镁的强络合作用而影响了桃树的正常生长这一推测。 桃胶经碱溶纯化制得钠型胶，再用阳离子交换树脂处理得氢型胶。用不同的方法处理桃胶后，桃胶红外光谱的结构特征吸收方才显示出来。钠型胶具840Cm-1的红外吸收;氢型胶具890Cm-1、1730cm-1的红外吸收;甲基化后的桃胶具810Cm-1、870Cm-1、890Cm-1的红外吸收。桃胶的比旋光度为负值。核磁共振证明桃胶多糖中，α-和β-甙键共存。碱溶纯化的桃胶多糖经凝胶色谱和超速离心证明为单一物质。 桃胶多糖不具还原性。经气相层析和比色法分析，桃胶中D-葡萄糖醛酸(包括4-甲氧基-D-葡萄糖醛酸）、D-半乳糖、D-木糖、D-甘露糖、L-阿拉伯糖、L-鼠李糖含量分别为10%、30%、11%、1.3%、45%、2%。18C-NMR和甲基化分析，证明桃胶大分子链是高度支链化的。且阿拉伯糖和半乳糖在大分子结构中有呋喃环和吡喃环两种形式共存。桃胶按物理性状，可分为两种。它们仅仅是在分子量和水溶液中的粘度不同，分子量( Mw)为342.9万和416.9万，特性粘度(η)为0.425dl/g和0.866dl/g。但在化学成分及结构特征上是相似的。以甘油为增塑剂，能增加桃胶成膜后的柔韧性。

中国近海典型海域沉积物中无机碳的形态研究

碳循环是影响地球环境中能量循环和物质流动的重要过程，而由于人类活动带来的大气CO2浓度升高对生态环境带来一系列的影响，如温室效应、海水酸化及全球灾害性气候增加等。海洋是地球上巨大的碳库，近海海域是连接陆地和海洋两大生态系统的关键环节，它接受着河流输入的大量陆源物质，并通过物理、化学和生物过程与大洋进行各种物质和能量交换。经过对海洋碳循环的多年研究，人们对碳在大洋中的迁移转化获得了比较清晰的认识，但对生物地球化学过程极为复杂的近海的研究还存在较多的不确定性。 元素的存在形态对其迁移转化有着重要影响，为研究近海不同形态无机碳，本文采用连续浸取方法，根据无机碳在沉积物中的结合强度，将无机碳分为交换态、弱碱结合态、强碱结合态、弱酸结合态和残渣态，分析了渤海湾、四十里湾附近海域、大亚湾和南海北部海域等中国典型近海海域表层及柱状沉积物中不同形态的无机碳含量，并讨论了其与各地球化学参数之间的关系，得到如下结论： 在各个研究区，沉积物中总无机碳的平均含量分别为：渤海湾6.16 mg/g，四十里湾附近海域7.51 mg/g，大亚湾3.08 mg/g，南海北部海域11.66 mg/g。渤海湾潮间带沉积物的无机碳含量普遍高于潮下带沉积物，四十里湾附近海域柱状样沉积物中无机碳含量一般随埋藏深度的增加而增加，大亚湾沉积物低的无机碳含量可能与低的陆源物质输入有关，南海北部海域表层沉积物无机碳含量分布表现出明显的近岸低深海高的分布特征，高的无机碳含量明显受生物活动影响。 渤海湾沉积物中各相无机碳的平均含量为氯化钠相0.63 mg/g、氨水相0.74 mg/g、氢氧化钠相0.28 mg/g、盐酸羟胺相3.13 mg/g、残渣相1.38 mg/g。四十里湾附近海域沉积物柱状样各形态无机碳含量为氯化钠相0.54 mg/g、氨水相0.36 mg/g、氢氧化钠相0.13 mg/g、盐酸羟胺相6.46 mg/g、残渣相0.02 mg/g。大亚湾沉积物中各相无机碳的平均含量为氯化钠相0.45 mg/g、氨水相0.50 mg/g、氢氧化钠相0.46 mg/g、盐酸羟胺相1.51 mg/g、残渣相0.16 mg/g。南海北部沉积物中各相无机碳的平均含量为氯化钠相0.52 mg/g、氨水相0.30 mg/g、氢氧化钠相0.17 mg/g、盐酸羟胺相3.79 mg/g、残渣相6.88 mg/g。在所研究的大部分近海沉积物中，盐酸羟胺相是沉积物无机碳的主要形态，只有南海北部海域表层沉积物比较特殊。 渤海湾潮下带沉积物中，碱浸取相（氢氧化钠相和氨水相）无机碳与沉积物总有机碳（TOC）和总氮（TN）之间存在较为紧密的联系；潮间带沉积物中，含水率、TOC、TN和粒度等地球化学参数与前3相及残渣相无机碳均有较紧密的联系。四十里湾附近海域柱状沉积物中，沉积物各参数对不同柱状样各形态无机碳的影响差异较大，位于芝罘岛附近的柱状样B主要受粒度影响，含水率、TOC和TN对离岸较近的柱状样D的前两相无机碳和崆峒岛北侧的柱状样E的氯化钠相无机碳有较大影响，沉积物各参数对崆峒岛南侧的柱状样C和离岸最远的柱状样S的影响相对较小。大亚湾沉积物各形态无机碳受环境影响的程度比其它海域弱。南海北部沉积物中，TOC对各形态无机碳影响较强，其中的氨水相无机碳与沉积物各参数间存在较为紧密的联系。 对比各海域的研究结果发现，不同无机碳形态之间，碱浸取相无机碳之间常存在正相关关系，氯化钠相作为比较活泼的无机碳形态，与其它各相之间的关系具有不确定性，弱酸浸取相无机碳与无机碳总量的关系较为紧密，残渣相与其它无机碳形态的关系一般较弱，说明此相无

池塘养殖环境下滇池金线鲃仔稚鱼的食性转化与生长

下载PDF阅读器2008年3月-2009年3月,把35 000尾滇池金线鲃(Sinocyclocheilus grahami)仔稚鱼分别饲养于3个池塘进行对比饲养研究.密度分别是:P1为208尾/m3;P2为167尾/m3;P3为41尾/m3.饲养期间采用相同的管理措施.每天数据收集采用:在仔鱼孵化后的5～16d的每天8:00和18:00从每个育苗池中捞取5～8尾仔鱼进行测量分析.仔鱼开口30d后,每月从培育池各捞取15尾,测量全长和体重.研究发现,滇池金线鲃仔鱼的开口时间为孵化后的5 d,混合营养期3～5d,这与初孵的演池金线鲃仔鱼的全长和卵黄囊较大有关.在容易造成仔鱼大量死亡的混合营养期,通过采用浆状物-轮虫-人工混合饲料的方式,大幅度提高了滇池金线鲃仔稚鱼的存活率,孵化一年后的滇池会线鲃稚鱼存活率可达82.7%.经过一周年的饲养,滇池金线鲃稚鱼的体重由(0.027±0.01)g(0.003～1.22)增长到(8.83±0.54)g (3.7～16.7),月均增重为0.73 g;全长由(15.8±0.30)mm (11.5～20.0)增长到(91.6±1.67)mm (75.0～16.0),全长月均增长6.32 mm.滇池金线鲃稚鱼全年全长的增长呈线性相关,y=9.82+7.05month(R2=0.9891);全年体重的增长呈指数关系,y=0.0158month2.54(R2=0.9939).

湖南尖吻吻蝮蛇毒两个出血毒素的纯化和理化性质

经Sephadex G-75凝胶过滤, QAE-Sephadex A-50和CM-Sephadex C-25离子交换层析, 从尖吻蝮蛇毒中纯化出两个出血毒素(DaHT-1和DaHT-2)。SDS-PAGE测得分子量均为23.5kD,IEF-PAGE测得等电点分别为5.6和5.2, DaHT-1和DaHT-2的最小出血剂量分别为0.5#mu#g和0.8#mu#g。都具蛋白水解酶活性, DaHT-1和DaHT-2的最适温度分别为35℃和40℃, 最 适pH为6-9, 对热均不稳定, 温度高于60℃活性完全丧失。图7表1参13

武汉东湖沉积物碳氮磷垂向分布研究

建立了东湖Ⅰ站90cm和Ⅱ站150cm沉积物剖面年代序列框架,研究了碳氮磷的垂向分布,并对碳-氮和碳-磷耦合进行了讨论。东湖Ⅰ站和Ⅱ站沉积物总有机碳(TOC)分别为3.00%和2.44%,总氮(TN)分别为0.45%和0.34%,总磷(TP)分别为1.11mg/g和0.69mg/g。东湖Ⅰ站和Ⅱ站沉积物TOC与TN之间呈极显著的正相关关系,TOC/TN质量比的变化是受到气候变化、人类活动、氮比有机碳分解速度快等因素综合作用的结果。TP与TOC之间也呈正相关关系,但相关性差,由于污水大量排入Ⅰ站,导致东湖Ⅰ

构建湿地中试系统基质剖面微生物活性的研究

对稳定运行的复合垂直流构建湿地中试系统基质进行分层采样,测定微生物数量,生物量氮,酶活性,硝化作用,反硝化作用以及呼吸作用等各项指标.结果表明,上行流和下行流池0~10cm的基质层中好氧微生物数量高出30~55cm的层面1~2个数量级;反硝化细菌除下行流池0~10cm的层面外其他基质层数量都达到107个/g干土以上.0~20cm的基质层中脲酶活性明显高于30~55cm的层面;而0~10cm的层面中脱氢酶活性明显高出10~55cm的层面2~5倍.硝化反硝化作用广泛存在于基质中,硝化作用表现出一定的空间规律,

武汉东湖不同湖区底泥总磷含量及变化的研究

以武汉东湖为对象 ,研究了 1 998.0 3— 1 999.0 2期间不同营养水平湖区底泥中 (0—5cm ,5— 1 0cm)总磷的含量及季节动态。 6个站平均总磷含量为 1 .1 5mg/g ,同 80年代初相比 ,Ⅰ、Ⅱ站底泥中总磷含量分别增高 1 .42倍和 1 .0 3倍。受污水排放影响较重的 0站磷含量高达 2 .78mg/g,而受污水排放影响较小的Ⅳ、Ⅴ站仅分别为 0 .52mg/g和 0 .50mg/g。东湖底泥中磷年平均含量与湖水中磷年平均浓度相关系数极高 (r=0 .997,n =5

Enhanced resistance to Aeromonas hydrophila infection and enhanced phagocytic activities in human lactoferrin-transgenic grass carp (Ctenopharyngodon idellus)

Human lactoferrin (hLF) is an iron-binding protein with antimicrobial and immunomodulatory activities. hLF cDNA was transferred into grass carp via electroporated sperm. The production of transgenic fish was as high as 55% tinder the best parameters. 2(11) pulses and 20-min incubation. The expression of the transgene was demonstrated by the detection of hLF mRNA by RT-PCR. We also investigated the response of G(0) transgenic grass carp to Aeromonas hydrophila infection. Serum lysozyme activities (P&gt;0.05) and phagocytic activities of kidney cells (P<0.05) were measured in transgenic individuals. The transgenic fish not only cleared A. hydrophila significantly faster than the control carp (P<0.05), but also showed enhanced phagocytic activities. The result shows that hLF has immunomodulatory activities in hLF-transgenic grass carp. The transgenic grass carp exhibited enhanced immunity to A. hydrophila infection. These results reveal that the mechanisms of disease resistance are different between hLF-transgenic plants and hLF-transgenic grass carp. (C) 2004 Elsevier B.V. All rights reserved.

Food consumption and growth of two piscivorous fishes, the mandarin fish and the Chinese snakehead

Rates of maximum food consumption and growth were determined for immature mandarin fish Siniperca chuatsi (47.2-540.2 g) and Chinese snakehead Channa argus (45.0-546.2 g) at 10, 15, 20, 25, 30 and 35 degrees C. The relationship between maximum rate of food consumption (C-max), body weight (W) and temperature (T) was described by the multiple regression equations: lnC(max) = -4.880 + 0.597 lnW+0.284T - 0.0048T(2) for the mandarin fish, and lnC(max)= -6.718 + 0.522 lnW+0.440T-0.0077T(2) for the Chinese snakehead. The optimum temperature for consumption was 29.6 degrees C for the mandarin fish and 28.6 degrees C for the Chinese snakehead. The relationship between growth rate (G), body weight and temperature was ln(G+0.25)= - 0.439 - 0.500 lnW+0.270T - 0.0046T(2) for the mandarin fish, and ln(G+0.25)= - 6.150+ (0.175 - 0.026T) lnW+0.571T - 0.0078T(2) for the Chinese snakehead. The weight exponent in the growth-weight relationship was -0.83 for the mandarin fish, but decreased with increasing temperature for the Chinese snakehead. The optimum temperature for growth was 29.3 degrees C for the mandarin fish, but tended to decrease with increasing weight for the Chinese snakehead, being 30.3 degrees C for a 45-g fish, and 26.1 degrees C for a 550-g fish. (C) 1998 The Fisheries Society of the British Isles.