黄海冷水团及邻近海域小型底栖动物多样性及其环境效应

2007年夏季对黄海冷水团及邻近海域共48个站位的小型底栖动物组成、丰度和生物量，以及环境因子进行了科考研究。所调查站位的小型底栖动物平均丰度达2194 ± 1598 inds./10cm2，其中北黄海17个站位平均丰度为3408 ± 1578 inds./10cm2，南黄海31个站位平均丰度为1529 ± 1121 inds./10cm2。调查站位平均生物量为1839 ± 1289 g dwt/10cm2，其中北黄海站位平均生物量为2760 ± 1340g dwt/10cm2，南黄海平均生物量为1335 ± 902g dwt/10cm2。在分选出的共18个小型底栖动物类群中，丰度上均以自由生线虫占绝对优势，达总量的88%，且在南（88.3%）、北黄海（87.7%）基本无差异。在生物量上，同样以自由生线虫贡献最多（42％），多毛类居次（22%），其他生物量较多的还有桡足类（13%）和甲壳类幼体（12%）。在小型底栖动物的垂直分布上，分布于沉积物表层0-2cm的小型底栖动物占79%，次表层2-5cm占17%，最底层5-8cm仅占4%。统计分析表明研究站位小型底栖动物丰度和生物量与沉积物叶绿素a、有机质含量、中值粒径显著或极显著正相关，与水深呈极显著负相关，此外小型底栖动物生物量与沉积物粉砂粘土含量显著负相关。 同年秋季搭载开放航次对黄海5个站位、东海3个站位、南海2个站位的小型底栖动物组成、丰度和生物量，以及环境因子进行了调查研究。对三个海域小型底栖动物的比较研究发现，平均丰度以黄海最高，达2132 ± 946 inds./10cm2，东海次之，为1954 ± 2047 inds./10cm2，而南海仅156 ± 56 inds./10cm2；三海域的平均生物量依次为2193 ± 1148 g dwt/10cm2、1865 ± 1555 g dwt/10cm2和212 ± 22 g dwt/10cm2。在分选出的共14个小型底栖动物类群中，丰度上均以自由生线虫占绝对优势，分别占总量的85%、89%、85%。在生物量上，黄海以自由生线虫贡献最多（33％），多毛类居次（18%）；东海二者比例相近（约37％），而南海则以多毛类占绝对优势（56％），线虫居次（25%）。在小型底栖动物的垂直分布上，三个海区差异较大：分布于沉积物表层0-2cm的小型底栖动物在黄海高达90%，东海仅46%，在南海为63%。统计分析表明，本研究站位小型底栖动物丰度与沉积物中的叶绿素a及脱镁叶绿素a含量和底温呈显著正相关，与水深呈显著负相关。该结果与本航次之后在广东湛江和海南以东的南海海域开展的908调查结果形成了鲜明对照，后者的小型底栖动物及线虫丰度与沉积物中有机质含量呈显著正相关，与水深呈显著负相关，表明近海受人类干扰影响较大。 本文利用微宇宙实验方法，来确定不同浓度梯度的Cu、Pb以及Cu/ Pb混合重金属污染物对青岛湾小型底栖动物（主要是线虫）的影响。加入污染物后，分别在1、3、7、14、21天进行取样分析。结果显示，Cu和Cu/Pb混合高浓度实验单元组的线虫丰度除在第21天有较明显减少外，在整个实验周期内基本没有变化，分析可能系高浓度Cu的固定作用从而使小型底栖动物无法腐烂降解造成的。同一时间尺度上，各重金属污染物实验单元的线虫丰度均高于（或接近于）空白对照组，较高浓度的重金属污染物实验单元的线虫丰度高于（或接近于）较低浓度重金属污染物实验单元，Cu/Pb混合低浓度实验单元的线虫丰度高于同一时间尺度Cu低浓度和Pb低浓度实验单元。推测是由于采样点的线虫群落中存在对Cu和Pb的耐受种或者“机会种”造成的。

伯胺N_(1923)萃取过渡金属离子机理的研究

伯胺由于其特殊的结构（R-NH_2），使它具有和仲、数胺不相同的一些性质。有较强的和矿物酸HX结合形成RNH_3X的能力，从而以离子交换机理萃取金属离子；也可以-NH_2上的氮、氢原子同以高价存在的过渡金属含氧酸以氢键方式相结合；另外，RNH_2也可通过氮原子以配位键形式与一些属于软酸类的过度金属离子形成配合物。通过伯胺萃取金属离子行为的研究，可发现新的萃取体系，扩大我国自行设计的伯胺N_(1923)萃取剂的应用领域，为金属离子的分离提纯工艺提供基本参数。我们实验室过去曾对伯胺N_(1923)萃取稀土（III）、Fe（III）、Zn （II）、Cd（II）、Ag���I）、Sc（III）等的机理进行了比较系统的研究。本工作是在此基础上，进一步完善及扩大N_(1923)对周期表中各族元素的萃取及应用。为此，我们选择了文献尚未报道的Ti（IV）、HgCl_2、Hg(CH_3COO)_2、Cu(CH_3COO)_2为研究对象，对它们的萃取机理进行了较详细的研究。结果表明，自由的N_(1923)或其盐对上述体系具有良好的萃取性能，并初步讨论了N_(1923)在金属离子萃取分离中的应用。一、伯胺N_(1923)萃取HgCl_2的机理 微量汞的萃取及分离对环境保护具有重要的实际意义。我们的研究结果表明，在pH值为3-4.5范围内，即使Cl~-浓度很低时，伯胺N_(1923)也能几乎定量地萃取HgCl_2，其盐酸盐亦能有效地萃取Hg���II），但两者的萃取机理不同。自由伯胺RNH_2可与HgCl_2形成配合物，其萃取机理为：RHN_(2(0)) + HgCl_2 <-> Hg(RNH_2)Cl_(2(0))对伯胺盐，实验证明其机理主要为加合反应，但当Cl~-浓度较高时，则为阴离子交换反应：加合反应：2RNH_3Cl_((0)) + HgCl_2 <-> (RNH_3Cl)_2HgCl_(2(0))交换反应：2RNH_3Cl_((0)) + HgCl_4~(2-) <-> (RNH_3)_2HgCl_(4(0)) + 2Cl~-通过考察温度对配位萃取反应的影响，求得反应的热效应ΔH = -48.82 KJ/mol，并分析了萃合物的IR、NMR谱。二、伯胺N_(1923)萃取Hg(CH_3COO)_2的机理 与HgCl_2体系相似，自由伯胺或其盐均能萃取Hg(CH_3COO)_2，萃取机理分别为：RNH_(2(0)) + Hg(CH_3CCO)_2 <-> Hg(RNH_2)(CH_3COO)_(2(0)) (CH_3COONH_3R)_(2(0)) + Hg(CH_3COO)_2 <-> (CH_3COONH_3R)_2Hg(CH_3COO)_(2(0))。在不同的萃取剂浓度下，上述反应的表观平衡常数基本不随萃取剂浓度的变化而改变，其对数值分别为：11.85、8.11。三、伯胺N_(1923)萃取Cu(CH_3COO)_2的机理 水相酸度对萃取反应的影响表明，RNH_2在近中性体系中具有很好的萃取性能，而在乙酸浓度较高的条件下，Cu（II）几乎不被RNH_2所萃取。说明自由伯胺能以配位机理的形式萃取Cu(Oh_3coo)_2，经确定，萃取反应式为：2RNH_(2(0)) + Cu(CH_3COO)_2 <-> Cu(RNH_2)_2(CH_3COO)_(2(0))并对该反应的表观平衡常数及热力学函数进行了计算。通过分析萃合物的IR谱，认为Cu(RNH_2)_2(CH_3COO)_2为平面型四配位的配合物。四、(RNH_3)_2SO_4从硫酸溶液中萃取Ti（IV）的研究 在低酸度（pH：0.84）的H_2SO_4溶液中，伯胺N_(1923)对Ti（IV）具有很强的萃取能力。用化学平衡法确定其反应式为：3(RNH_3)_2SO_(4(0)) + Ti(OH)_3~+ + SO_4~(2-) <-> 2(RNH_3)_3Ti(OH_3)(SO_4)_(2(0))我们用正十二胺代替N_(1923)，合成了上述萃合物的模拟物，经元素分析确定了萃合物的分子式：(RNH_3)_3Ti(OH)_3(SO_4)_2。并较详细地分析了萃合物的NMR、IR谱。变温NMR的结果表明，萃合物中存在两种含有活泼氢的基团，用D_2O交换后的NMR的结果亦证明了这一点。从萃合物的IR谱中，可得到SO_4~(2-)是以单齿配位形式同Ti（IV）相结合的信息。这些结果为所提出的萃取机理提供了直接的证据。并求出了上述萃取反应的表观平衡常数，其对数值为10.15，该值基本不随萃取剂浓度的变化而发生改变。反应的热效应ΔH = 66.49 KJ/mol，由计算得出的ΔG���可知，上述萃取反应有很大的向右进行的趋势。五、伯胺N_(1923)在萃取分离中的应用 为了扩大N_(1923)的应用，通过上述研究，我们对其在萃取分离中的应用进行了讨论，认为在以下几方面有可能得到应用：1、从环境废水中除Hg(II)；2、Hg(II)和Zn(II)、Cd(II)在CH_3COOH体系中的分离；3、CH_3COOH体系中Cu(II)、Co(II)、Ni(II)的萃取分离；4、在较高浓度的H_2SO_4体系中，应用(RNH_3)_2SO_4进行了Ti(IV)-Fe(II)的分离。

Characterization and mapping of expressed sequence tags isolated from a subtracted cDNA library of Litopenaeus vannamei injected with white spot syndrome virus

A large number of polymorphic simple sequence repeats (SSRs) or microsatellites are needed to develop a genetic map for shrimp. However, developing an SSR map is very time-consuming, expensive, and most SSRs are not specifically linked to gene loci of immediate interest. We report here on our strategy to develop polymorphic markers using expressed sequence tags (ESTs) by designing primers flanking single or multiple SSRs with three or more repeats. A subtracted cDNA library was prepared using RNA from specific pathogen-free (SPF) Litopenaeus vannamei juveniles (similar to 1 g) collected before (0) and after (48 h) inoculation with the China isolate of white spot syndrome virus (WSSV). A total of 224 clones were sequenced, 194 of which were useful for homology comparisons against annotated genes in NCBI nonredundant (nr) and protein databases, providing 179 sequences encoded by nuclear DNA, 4 mitochondrial DNA, and 11 were similar to portions of WSSV genome. The nuclear sequences clustered in 43 groups, 11 of which were homologous to various ESTs of unknown function, 4 had no homology to any sequence, and 28 showed similarities to known genes of invertebrates and vertebrates, representatives of cellular metabolic processes such as calcium ion balance, cytoskeleton mRNAs, and protein synthesis. A few sequences were homologous to immune system-related (allergens) genes and two were similar to motifs of the sex-lethal gene of Drosophila. A large number of EST sequences were similar to domains of the EF-hand superfamily (Ca2+ binding motif and FRQ protein domain of myosin light chains). Single or multiple SSRs with three or more repeats were found in approximately 61 % of the 179 nuclear sequences. Primer sets were designed from 28 sequences representing 19 known or putative genes and tested for polymorphism (EST-SSR marker) in a small test panel containing 16 individuals. Ten (53%) of the 19 putative or unknown function genes were polymorphic, 4 monomorphic, and 3 either failed to satisfactorily amplify genomic DNA or the allele amplification conditions need to be further optimized. Five polymorphic ESTs were genotyped with the entire reference mapping family, two of them (actin, accession #CX535973 and shrimp allergen arginine kinase, accession #CX535999) did not amplify with all offspring of the IRMF panel suggesting presence of null alleles, and three of them amplified in most of the IRM F offspring and were used for linkage analysis. EF-hand motif of myosin light chain (accession #CX535935) was placed in ShrimpMap's linkage group 7, whereas ribosomal protein S5 (accession #CX535957) and troponin I (accession #CX535976) remained unassigned. Results indicate that (a) a large number of ESTs isolated from this cDNA library are similar to cytoskeleton mRNAs and may reflect a normal pathway of the cellular response after im infection with WSSV, and (b) primers flanking single or multiple SSRs with three or more repeats from shrimp ESTs could be an efficient approach to develop polymorphic markers useful for linkage mapping. Work is underway to map additional SSR-containing ESTs from this and other cDNA libraries as a plausible strategy to increase marker density in ShrimpMap.

Direct numerical test of the B-G-K model equation by the DSMC method

In the present paper the rarefied gas how caused by the sudden change of the wall temperature and the Rayleigh problem are simulated by the DSMC method which has been validated by experiments both in global flour field and velocity distribution function level. The comparison of the simulated results with the accurate numerical solutions of the B-G-K model equation shows that near equilibrium the BG-K equation with corrected collision frequency can give accurate result but as farther away from equilibrium the B-G-K equation is not accurate. This is for the first time that the error caused by the B-G-K model equation has been revealed.

Immunosensor Interface Based on Physical and Chemical Immunogylobulin G Adsorption onto Mixed Self-Assembled Monolayers

An immunosensor interface based on mixed hydrophobic self-assembled monolayers (SAMs) of methyl and carboxylic acid terminated thiols with covalently attached human Immunoglobulin G (hIgG), is investigated. The densely packed and organised SAMs were characterised by contact angle measurements and cyclic voltammetry. The effect of the non-ionic surfactant, Tween 20, in preventing nonspecific adsorption is addressed by ellipsometry during physical and covalent hIgG immobilization on pure and mixed SAMs, respectively. It is clearly demonstrated that nonspecific adsorption due to hydrophobic interactions of hIgG on methyl ended groups is totally inhibited, whereas electrostatic/hydrogen bonding interactions with the exposed carboxylic groups prevail in the presence of surfactant. Results of ellipsometry and Atomic Force Microscopy, reveal that the surface concentration of covalently immobilized hIgG is determined by the ratio of COOH/CH3-terminated thiols in SAM forming solution. Moreover, the ellipsometric data demonstrates that the ratio of bound anti-hIgG/hIgG depends on the density of hIgG on the surface and that the highest ratio is close to three. We also report the selectivity and high sensitivity achieved by chronoamperometry in the detection of adsorbed hIgG and the reaction with its antibody.

Numerical simulation of g-jitter effects on half floating zone convection under microgravity environment

The g-jitter effects on the thermocapillary convection in liquid bridge of floating half zone were studied by numerical simulation for unsteady and axi-symmetric model in the cylindrical coordinate system. The g-jitter field was given by a steady microgravity field in addition to an oscillatory low-gravity field, and the effects on the flow field, temperature distribution and free surface deformation were analyzed numerically.

G-jitter effects on half floating-zone convection in intermediate-frequency range

The g-jitter influence on thermocapillary convection and critical Marangoni number in a liquid bridge of half-floating rone was discussed in the low frequency range of 0.4 to 1.5 Hz in a previous paper. This paper extended the experiments to the intermediate frequency range of 2 to 18 Hz, which htrs often been recorded as vibration environment of spacecrafts. The experiment was completed on the deck of a vibration machine, which gave a periodical applied acceleration to simulate the effects of g-jitter. The experimental results in the intermediate frequency range are different from that in the low frequency range. The velocity field and the shape of the free surface have periodical fluctuations in response to g-jitter. The amplitude of the periodical varying part of the temperature response decreases obviously with increasing frequency of g-jitter and vanishes almost when the frequency of g-jitter is high enough. The critical Marangoni number is defined to describe the transition from a periodical convection in response to g-jitter to an oscillatory convection due to internal instability, and will increase with increasing g-jitter frequency. According to the spectral analysis, it can be found that the oscillatory part of temperature is a superposition of two harmonic waves if the Marangoni number is larger than a critical value.

Effects of g-jitter on the critical marangoni number

A half floating zone is fixed on a vibrational deck, which supports a periodical applied acceleration to simulate the effect of g-jitter. This paper deals with the effects of g-jitter on the fluid fields and the critical Marangoni number, which describes the transition from a forced oscillation of thermocapillary convection into an instability oscillatory convection in a liquid bridge of half floating zone with top rod heated. The responses of g-jitter field on the temperature profiles and flow pattern in the liquid bridge were obtained experimentally. The results indicated that the critical Marangoni number decreases with the increasing of g-jitter effect and is slightly smaller for higher frequency of g-jitter with fixed strength of applied gravity.

Quantum and variational monte-carlo interaction potentials for li2 (x1-sigma-g+)

Optimized trial functions are used in quantum Monte Carlo and variational Monte Carlo calculations of the Li₂(X ¹&Sigma;⁺_g) potential curve. The trial functions used are a product of a Slater determinant of molecular orbitals multiplied by correlation functions of electron—nuclear and electron—electron separation. The parameters of the determinant and correlation functions are optimized simultaneously by reducing the deviations of the local energy EL (EL  Ψ⁻¹THΨT, where ΨT denotes a trial function) over a fixed sample. At the equilibrium separation, the variational Monte Carlo and quantum Monte Carlo methods recover 68% and 98% of the correlation energy, respectively. At other points on the curves, these methods yield similar accuracies.</sub>

源于G.I.Taylor工作的现代经典物理学

一位科学家的工作提供了一门完整课程的素材，涉及从流体动力学稳定性、湍流到流体电动力学、微生物的运动．

Starting Nozzle Flow Simulation Using K-G Two-Equation Turbulence Model

The starting process of two-dimensional nozzle flows has been simulated with Euler, laminar and k - g two-equation turbulence Navier-Stokes equations. The flow solver is based on a combination of LUSGS subiteration implicit method and five spatial discretized schemes, which are Roe, HLLE, MHLLE upwind schemes and AUSM+, AUSMPW schemes. In the paper, special attention is for the flow differences of the nozzle starting process obtained from different governing equations and different schemes. Two nozzle flows, previously investigated experimentally and numerically by other researchers, are chosen as our examples. The calculated results indicate the carbuncle phenomenon and unphysical oscillations appear more or less near a wall or behind strong shock wave except using HLLE scheme, and these unphysical phenomena become more seriously with the increase of Mach number. Comparing the turbulence calculation, inviscid solution cannot simulate the wall flow separation and the laminar solution shows some different flow characteristics in the regions of flow separation and near wall.