四倍体鱼的种质改良研究

β—actin基因启动子驱动的草鱼生长激素基因cDNA—“全鱼”基因 pCAgcGHc用显微注射方法导入四倍体鱼卵 ,获得了生长快 ,个体硕壮的转基因四倍体鱼。 2 4 0日龄时 ,转基因鱼平均体重为 30 2 7g ,是对照鱼的 3 1倍 ,平均体长是对照的 1 34倍 ,并可从部分转基因雄鱼挤出精液 ,而对照鱼尚无此现象。对 19尾转基因四倍体雄鱼的精液和尾鳍DNA做PCR检测 ,外源基因的阳性率分别为 94 7%和 52 6%。最后 ,展望了转基因四倍体鱼在转基因鱼产业化方面的应用前景

对磷酸氢钙(HG2636-94)检测方法的改进建议

本文对饲料级磷酸氢钙标准(HG2636-94)检测方法中钙含量的测定、氟含量的测定存在的问题进行了探讨,并提出了解决方法.利用分散剂消除磷酸根对钙测定的干扰,EDTA直接络合滴定钙,方法快速准确;控制适当的试科量以保证氟检测结果的准确度.

PCR-DGGE Fingerprinting Analysis of Plankton Communities and Its Relationship to Lake Trophic Status

Plankton communities in eight lakes of different trophic status near Yangtze, China were characterized by using denatured gradient gel electrophoresis (DGGE). Various water quality parameters were also measured at each collection site. Following extraction of DNA from plankton communities, 16S rRNA and 18S rRNA genes were amplified with specific primers for prokaryotes and eukaryotes, respectively; DNA profiles were developed by DGGE. The plankton community of each lake had its own distinct DNA profile. The total number of bands identified at 34 sampling stations ranged from 37 to 111. Both prokaryotes and eukaryotes displayed complex fingerprints composed of a large number of bands: 16 to 59 bands were obtained with the prokaryotic primer set; 21 to 52 bands for the eukaryotic primer set. The DGGE-patterns were analyzed in relation to water quality parameters by canonical correspondence analysis (CCA). Temperature, pH, alkalinity, and the concentration of COD, TP and TN were strongly correlated with the DGGE patterns. The parameters that demonstrated a strong correlation to the DGGE fingerprints of the plankton community differed among lakes, suggesting that differences in the DGGE fingerprints were due mainly to lake trophic status. Results of the present study suggest that PCR-DGGE fingerprinting is an effective and precise method of identifying changes to plankton community composition, and therefore could be a useful ecological tool for monitoring the response of aquatic ecosystems to environmental perturbations.

Detection of the hepatotoxic microcystins in 36 kinds of cyanobacteria Spirulina food products in China

Gel filtration chromatography, ultra-filtration, and solid-phase extraction silica gel clean-up were evaluated for their ability to remove microcystins selectively from extracts of cyanobacteria Spirulina samples after using the reversed-phase octadecylsilyl ODS cartridge for subsequent analysis by liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). The reversed-phase ODS cartridge/silica gel combination were effective and the optimal wash and elution conditions were: H2O (wash), 20% methanol in water (wash), and 90% methanol in water (elution) for the reversed-phase ODS cartridge, followed by 80% methanol in water elution in the silica gel cartridge. The presence of microcystins in 36 kinds of cyanobacteria Spirulina health food samples obtained from various retail outlets in China were detected by LC-MS/MS, and 34 samples (94%) contained microcystins ranging from 2 to 163 ng g(-1) (mean=1427 ng g(-1)), which were significantly lower than microcystins present in blue green alga products previously reported. MC-RR-which contains two molecules of arginine (R)-(in 94.4% samples) was the predominant microcystin, followed by MC-LR-where L is leucine-(30.6%) and MC-YR-where Y is tyrose-(27.8%). The possible potential health risks from chronic exposure to microcystins from contaminated cyanobacteria Spirulina health food should not be ignored, even if the toxin concentrations were low. The method presented herein is proposed to detect microcystins present in commercial cyanobacteria Spirulina samples.

Optical properties of boron-doped Si nanowires

Raman scattering and photoluminescence (PL) of boron-doped silicon nanowires have been investigated. Raman spectra showed a band at 480 cm(-1), indicating that the crystallinity of the nanowires was suppressed by boron doping. PL taken from B-doped SiNWS at room temperature exhibited three distinct emission peaks at 1.34, 1.42. and 1.47 eV and the PL intensity was much stronger than that of undoped SiNWS. The increased PL intensity should be very profitable for nano-optoelectronics. (C) 2004 Elsevier B.V. All rights reserved.

Photoluminescence of low-dimensional semiconductor structures under pressure

Photoluminescence of some low-dimensional semiconductor structures has been investigated under pressure. The measured pressure coefficients of In0.55Al0.45 As/Al0.5Ga0.5As quantum dots with average diameter of 26, 52 and 62 nm are 82, 94 and 98 meV/GPa, respectively. It indicates that these quantum dots are type-I dots. On the other hand, the measured pressure coefficient for quantum dots with 7 nm in size is -17meV/GPa, indicating the type-II character. The measured pressure coefficient for Mn emission in ZnS:Mn nanoparticles is -34.6meV/GPa, in agreement with the predication of the crystal field theory. However, the DA emission is nearly independent on pressure, indicating that this emission is related to the surface defects in ZnS host. The measured pressure coefficient of Cu emission in ZnS: Cu nanoparticles is 63.2 meV/GPa. It implies that the acceptor level introduced by Cu ions has some character of shallow level. The measured pressure coefficient of Eu emission in ZnS:Eu nanoparticles is 24.1 mev/GPa, in contrast to the predication of the crystal field theory. It may be due to the strong interaction between the excited state of Eu ions and the conduction band of ZnS host.

Room temperature (34 degrees C) operation of strain-compensated quantum cascade lasers

A short wavelength (lambda similar or equal to 3.5 mu m) strain-compensated InxGa(1-x)As/InyAl(1-y)As quantum cascade laser is reported. Quasi-continuous wave operation of this device at 34 degrees C with an output power of 11.4mW persisted for more than 30 minutes without obvious degradation. A very low threshold current density of 1.2KA/cm(2) at this temperature was observed.

长光程薄层光谱电化学法研究溶液反应及电极表面行为

本论文用光谱电化学法进行了有机分子的电极过程动力学和电极/溶液界面状态两个方面的研究。采用长光程光透薄层光谱电化学池，不仅测定了有关的热力学参数，研究和阐明了电极反应历程和机理，进一步提出和发展了用薄层光谱电化学研究快速反应的动力学方法；而且开展了电非活性分子在电极表面上吸附、定向、及其定向转化的热力学研究，另外发现和研究了电致二色性效应。首次研究了阳离子表面活性剂—溴化十六烷基吡啶（CPB）在玻碳电极表面上吸附行为，由光谱电化学实验结果和分子结构提出CPB在玻碳表面上吸附有四种较稳定的定向，经历了三次较大的吸附定向的转化过程，给出了分子在电极表面吸附的分子水平的微观信息。并表明微分吸附等温曲线法是研究有机物吸附定向及其转化的更为敏锐的方法。吸附等温曲线的理论处理，证明了CPB的每一定向吸附过程服从两个Frumkin等温吸附方程前者主要由化学亲合力控制，后者由晶格吸引力控制。揭示了长链烷烃的吸附特性，解释了CPB及某些中性有机化合物在高覆盖度下偏离Frumkin等温吸附方程的现象。提出了临界覆盖度概念，从而首次进行了吸附定向及其转化的热力学处理。获得各种吸附定向的吸附自由能及吸附定向转化的自由能变化和热力学平衡常数。从热力学方面预测了各种吸附定向的稳定性，吸附定向转化的推动力和可能性。从而深化了吸附的理论研究，使得较复杂有机化合物的复杂吸附过程的理论处理成为可能。CPB在玻碳电极表面上吸附的交流阻抗研究表明，在高频区出现了与电解池结构有关的阻抗，具有半园旋转特性。通过假设存在着频率相关的电容和电阻与池结构电容、溶液电阻构成等效电路。理论处理的予计结果完全与我们的实验吻合，而且对于文献中交流阻抗图高频端出现的变形现象提出了定性地解释。通过假定CPB在玻碳电极表面上形成单分子吸附膜的模型，推导出的结果（与吸附有关的阻抗图及warburg阻抗图）与实验数据完全一致。由warburg阻抗中求出的CPB扩散系数为7.07 * 10~(-8)cm~2/s，流体动力学半径为3.52A°，证明了CPB分子在LOPTLC中，由于流体场的作用形成有序排列，其扩散过程为CPB分子的群体行为，为CPB电致二色性研究提供依据。微分电容曲线的研究证明，在较低覆盖度下，CPB上的BF与电极表面接触，在电场作用下，CPB分子发生定向转化，由低密度定向向高密度定向转化，出现了多个峰电容。在较高覆盖度下，CPB中的BF离子离开电极表面，吸附行为与中性有机物的吸附行为相似，仅出现两个峰电容，没有BF的吸附—解吸峰。从而为由吸附等温曲线中推测的吸附定向提供依据。首次发现并研究了CPB的电致二色性效应，结果表明，CPB的电致二色性疚主要是由于偶极分子在电场作用下进行重新定向引起的。进一步研究了CPB浓度及有效电场强度的影响，电致二色性效应在低电位下与CPB的浓度成反比，较高电位下，与ECOSO呈正比。在高电位下，由于电化学反应引起有效电场强度降低，使电致二色性效应下降。这一研究为液晶体系中电致二色性的研究提供了有力的工具，扩展了研究的因素，也为光谱电化学方法研究液晶体系的电化学提供了基础性研究体系。茜素红S（ARS）在玻碳电极上电极行为的研究证明了，在1.0—0.0伏电位范围内，ARS的氧化过程不是一步不可逆过程，而是2个电子的氧化过程与一个后行化学反应构成了ECE循环机理。氧化和还原过程中还包括了一个质子的两电子氧化还原步骤和一个质子传递步骤构成的EC和CE机理。后行化学反应为ARS氧化产物与ARS形成氢键的反应，化学反应的产物经历一个不可逆氧化还原过程，还原产物为ARS。光谱电化学方法求得表观式电位为，E' = 0.34 5伏（VS·SCE），αn = 0.625。首次提出了单电位跃计时吸收法（用LOPTLC）测定快速后行化学反应速率的方法，测得ARS的后行化学反应平衡常数为7.94 * 10~5 l/mol，反应自由能为，8.05 kcal/mol (25 ℃)，与其它方法估计的结果吻合。测出的动力学速率常数为426.6 l/mol·s。扩展了LOPTLC法在快速反应动力学方面的应用。以上研究结果表明，本论文发展了光透式薄层光谱电化学的研究和应用范围，克服了以往多用于研究溶液反应的局限性，使此方法在研究电极/溶液界面现象方面能够与反射式光谱电化学法相比，而且具有方法简单，反映直观、测定灵敏、定量的特点，将有力地推动今后这方面的研究发展。

Shubnikov de Haas oscillations of a two-dimensional electron gas in a modulation-doped Zn0.80Cd0.20Se/ZnS0.06Se0.94 single quantum well

The magnetotransport properties of the two-dimensional (2D) electron gas confined in a modulation-doped Zn0.80Cd0.20Se/ZnS0.06Se0.94 single quantum well structure were studied at temperatures down to 0.35 K in magnetic fields up to 7.5 T. Well resolved 2D Shubnikovde Haas (SdH) oscillations were observed, although the conductivity of the sample in the as grown state was dominated by a bulk parallel conduction layer. After removing most of the parallel conduction layer by wet chemical etching the amplitude and number of SdH oscillations increased. From the temperature dependence of the amplitude the effective mass of the electrons was estimated as 0.17 m(0). Copyright (C) 1996 Published by Elsevier Science Ltd

高维空间点覆盖方法在物种计算机自动分类中的应用

长期以来物种的分类主要依靠形态学方法，难以形成计算机自动分类，本文提出了一种基于高维空间几何分析的序列对比方法，并应用该方法对9个嗜肝病毒科病毒和14个花椰菜花叶病毒科病毒做出了进化树，结果完全符合国际病毒学命名委员会公布的病毒分类标准，在此基础上，本文探索性的提出了一种基于仿生模式识别的物种自动分类方法，并应用该方法对嗜肝病毒科病毒和花椰菜花叶病毒科病毒做了自动分类，正确分类率分别达到100％和94％。

半导体低维结构的压力光谱研究

研究了一些半导体低维结构的压力光谱.测得平均直径为26、52和62nm的In0.55Al0.45As/Al0.5Ga0.5As量子点发光峰的压力系数分别为82、94和98 meV/GPa.表明这些发光峰具有Γ谷的特性,这些量子点为Ⅰ型量子点.而平均直径为7nm的量子点发光峰的压力系数为-17 meV/GPa,具有X谷的特性.所以这种小量子点为Ⅱ型量子点.测得ZnS:Mn纳米粒子中Mn发光峰的压力系数为-34.6meV/GPa,与晶体场理论的预计一致.而DA对发光峰基本不随压力变化,表明它应该与ZnS基体中的表面缺陷有关.测得ZnS:Cu纳米粒子中Cu的发光峰的压力系数为63.2meV/GPa,与ZnS体材料的带隙压力系数相同.表明Cu引入的受主能级具有浅受主的某些特点.测得ZnS:Eu纳米粒子中Eu发光峰的压力系数为24.1meV/GPa,与晶体场理论的预计不同.可能和Eu的激发态与ZnS导带间的相互作用有关.

Terahertz Quantum Cascade Laser Operating at 2.94 THz

The development of quantum cascade laser at 2.94 THz is reported. The laser structure is based on a bound-to-continuum active region and a semi-insulating surface-plasmon waveguide. Lasing is observed up to a heat-sink temperature of 70 K in pulsed mode with light power of 4.75 mW at 10 K and 1 mW at 70 K. A threshold current density of 296.5 A/cm(2) and an internal quantum efficiency of 1.57 x 10(-2) per cascade period are also observed at 10 K. The characteristic temperature of this laser is extracted to be T-0 = 57.5 K.

重金属污染土壤的自养菌和异养菌淋滤修复研究

本文以冶炼厂和张士灌区土壤为修复对象，以镉、铅、锌、铜为目标污染物，在室内模拟实验条件下，利用自养菌-嗜酸性氧化亚铁硫杆菌和异养菌-黑曲霉淋滤技术修复重金属污染土壤。在考察自养菌和异养菌对重金属污染土壤修复效果的基础上，重点研究了溶解性有机质和耐酸性异养菌对淋滤修复的影响和机制，同时筛选确定替代蔗糖黑曲霉发酵产酸的廉价碳源。结果发现： 自养菌-氧化亚铁硫杆菌淋滤修复过程中，筛选鉴定嗜酸性氧化亚铁硫杆菌R2对甲酸、乙酸、丙酸、草酸、苹果酸和柠檬酸的耐受浓度分别为0.1、0.4、0.4、2.0、20和40 mmol/L，而高效液相色谱测定沈阳冶炼厂土壤和张士灌区土壤中低分子量有机酸浓度很低，其中草酸含量最高，分别仅为0.04mmol/L和0.149mmol/L，远低于氧化亚铁硫杆菌能耐受的有机酸浓度。同时土壤中溶解性有机质对氧化亚铁硫杆菌R2氧化Fe2+未产生抑制作用，而耐酸性异养微生物H1（红酵母菌）和H2（头孢霉）的加入对氧化亚铁硫杆菌R2淋滤去除重金属效果未产生明显促进作用，本研究中分离筛选的嗜酸性氧化亚铁硫杆菌R2可直接应用于污染土壤的生物淋滤修复。经过5d的生物淋滤，冶炼厂土壤中Cu、Zn和Cd的最高去除率分别为30.6%、58.4%和72%。 在一步黑曲霉生物淋滤过程中，当固液比5%（w/v）、接种量3%（v/v）和淋滤修复7d时，对冶炼厂土壤来说，Cu、Cd、Pb和Zn去除率分别为75.8%，100%，30.6%和26.1%；张士灌区土壤中分别为54%，71.8%，9.5%，18.7%。在二步黑曲霉生物淋滤过程中，当固液比10%（w/v）、接种量为2%（v/v）和黑曲霉发酵时间7d，淋滤2d时，冶炼厂土壤中四种重金属去除率分别为Cu 84%，Cd 75.5%，Pb30.5%和Zn10%；张士灌区土壤中Cu、Cd、Pb和Zn的去除率分别达到57%，94.8%，20.4%和17.5%。 异养菌-黑曲霉淋滤修复重金属污染土壤效果优于有机酸淋滤。与黑曲霉淋滤相比，在直接添加有机酸淋滤修复中，冶炼厂土壤中重金属去除率分别为Cu 46.4%，Cd 61.8%，Pb 30.2%和Zn 43.3%，张士灌区土壤中重金属去除率分别为Cu 44%，Cd 0%，Pb 0%和Zn 26.2%。 淋滤前后土壤中重金属形态分级结果表明，黑曲霉一步和二步淋滤修复能有效去除污染土壤中交换态、碳酸盐结合态部分重金属，并能显著降低氧化物结合态部分重金属，但对有机态和残余态部分重金属离子去除效果并不明显。 以树木落叶和农作物副产品作为廉价碳源实施黑曲霉淋滤实验表明：杨树叶、桃树叶、土豆皮和玉米芯产酸和去除重金属效果较好。杨树叶对冶炼厂土壤中重金属去除率分别为63.5% Cu、100% Cd、16.8% Pb和Zn 27%；桃树叶去除效果分别为Cu61.8%、Cd100%、14.6%Pb和28.5%Zn；土豆皮去除效果分别为61%Cu、100%Cd、10.6%Pb和34%Zn。这些廉价碳源的利用可降低污染土壤生物淋滤修复成本。 研究生物淋滤修复技术为重金属污染土壤处理与处置开辟了新途径。