Study on the technology of thermal cracking of paraffin to alpha olefins

Alpha olefins are mainly produced from paraffin cracking in China, but their quality is not good because of bad quality of cracking feed and outdated technology. The technology of paraffin once-through cracking, paraffin recycle cracking of removing the heavy fraction after wax vaporizing and that of removing the heavy fraction before wax vaporizing were investigated in this paper. It was found that the technology of paraffin recycle cracking of removing the heavy fraction before wax vaporizing is new and better under the same operating conditions. Using hard paraffin (mp 54-56 degrees C) as feed, the high-quality alpha olefins products (C-5-C-21) containing more than 97 wt% of olefins and more than 88 wt% of alpha olefins are produced under optimum process conditions, which are a steam to paraffin ratio of 15 wt%, process temperature of 600 degrees C, low hydrocarbon partial pressure and residence time of 2 s. In addition, with the technology of the second injecting steam in ethylene cracking used in paraffin cracking, producing coke in paraffin cracking furnace has been markedly reduced.

Species transformation of trace elements and their distribution prediction in dyestuff residue incineration

The release of heavy metals from the combustion of hazardous wastes is an environmental issue of increasing concern. The species transformation characteristics of toxic heavy metals and their distribution are considered to be a complex problem of mechanism. The behavior of hazardous dyestuff residue is investigated in a tubular furnace under the general condition of hazardous waste pyrolysis and gasfication. Data interpretation has been aided by parallel theoretical study based on a thermodynamic equilibrium model based on the principle of Gibbs free energy minimization. The results show that Ni, Zn, Mn, and Cr are more enriched in dyestuff residue incineration than other heavy metals (Hg, As, and Se) subjected to volatilization. The thermodynamic model calculation is used for explaining the experiment data at 800 degrees C and analyzing species transformation of heavy metals. These results of species transformation are used to predict the distribution and emission characteristics of trace elements. Although most trace element predictions are validated by the measurements, cautions are in order due to the complexity of incineration systems.

氢化物发生石墨炉原子吸收光谱研究

石墨管原位富集氢化物是近年来研究者比较感兴趣的一个问题，本工作建立了自己的氢化物发生石墨炉原位富集系统。结果表明：氢化物发生器的体积和导气管的材料均影响分析灵敏度，氢化物直接富集在石墨管内壁上比在平台上效果好，石墨炉作原子化器，可以大大减小氢化物形成元素的干扰，涂钯石墨管能在较低温度下富集氢化物应与钯的催化性能有关。

滇金丝猴细菌人工染色体文库构建及Neurotrypsin基因的分子进化研究

本文包括两方面有关灵长类的研究工作。一是构建了一个非人灵长类（滇金丝猴）的人工染色体文库（BAC文库），为进一步研究灵长类的基因组进化奠定了一定的基础，二是对一个认知相关基因neuotrypsin在灵长类中的分子进化进行了详尽的研究，以期从分子进化角度认识该基因在灵长类高级认知功能发展中所起的作用。滇金丝猴（Rhinopithecusbieti），一个处于严重濒危状态的旧大陆猴，中国特产灵长类之一。在系统发育上它占据着旧大陆猴与小猿的中间地位，是研究灵长类进化的一个重要物种。，在本研究中，我们构建了一个滇金丝猴的细菌人工染色体文库（BAC文库）。该文库含有136320个BAC克隆，平均插入片段大小为148kb，小片段（50-100kb）所占的比例为2.74％，非重组克隆仅占2.67％。假定金丝猴与亲缘关系较近的灵长类有着相似的基因组大小，该文库至少有6倍的基因组覆盖率。对随机选取的BAC克隆进行末端测序，我们获得了201个序列标签（STS）。通过荧光原位杂交（FISH）技术，139个经末端测序的BAC克隆被精确定位到滇金丝猴的染色体上。荧光杂交实验还表明了人和金丝猴染色体产存在着高度的同线保守性。在人类基因组数据库中的Blast搜寻的结果显示染色体上的克隆数目与染色体大小呈很好的相关性，表明该文库克隆比较均匀地覆盖了滇金丝猴的基因组。该金丝猴文库及所定位的克隆将会成为非人灵长类的比较基因组研究和大规模基因组测序的一个宝贵的资源。Neurotrypsin是与个主要在脑中表达的，同神经发育和认知功能相关的胞外丝氨酸蛋白酶。它在人体中发生的突变与常染色体上隐性的非综合性精神发育迟缓（MR）紧密相关。我们通过对n个非人灵长类，包括大猿、小猿、旧大陆猴和新大陆猴neurotrypsin的编码区的测序，研究了neurotrypsin在灵长类中的分子进化。结果显示出，在灵长类进化过程中，neurotrypsin保持着由纯化性选择（负沟选择）所致的强烈的功能限制，这暗示着neurotrypsin在灵长类的认知发展中起着关键的功能性作用。进一步的分析表明，纯化性选择实际上只作用于neurotrypsin的介导其结合到其它细胞表面或胞外蛋白质的SRCR功能结构域上。另外，通过灵长类和其它哺乳动物目的比较，我们还发现，在鼠neuotrypsin中，一个人SRCR结构域（外显子2和3）的缺失是由于在鼠科动物中所发生的片段丢失事件所致。

金环蛇蛇毒丝氨酸蛋白酶抑制剂和三种胡蜂蜂毒的研究

蛇毒和蜂毒是提供药理学活性分子的丰富来源，它们富含肽和蛋白，包括一 些酶类和毒素。 丝氨酸蛋白酶抑制剂广泛存在于动物、植物和微生物体内，参与许多重要的 生理过程，如血液凝集、纤维蛋白溶解、细胞凋亡、发育以及炎症反应和补体活 化等（van Gent D. et al., 2003）。通过凝胶过滤、离子交换和反向高压液相色谱， 我们从金环蛇毒液中纯化得到一种天然的丝氨酸蛋白酶抑制剂，命名为 bungaruskunin。并且从该蛇的毒腺cDNA 文库中克隆到了它的核苷酸序列。 bungaruskunin 预测的前体由83 个氨基酸组成，包括含有24 个氨基酸的信号肽 和含有59 个氨基酸的成熟肽。它与一种由红腹伊澳蛇（Pseudechis porphyriacus） 的cDNA 预测到的丝氨酸蛋白酶抑制剂blackelin 具有最大相似性，达64％。 Bungaruskunin 是一种Kunitz 型的蛋白酶抑制剂，具有一个保守的Kunitz 结构域， 能够抑制胰蛋白酶、胰凝乳蛋白酶和弹性蛋白酶。通过对金环蛇毒腺cDNA 文库 的筛选，我们还得到了另外两条β-bungarotoxin B 链，Bungaruskunin 的整体结 构与β-bungarotoxin B 链相似，特别是它们都具有高度保守的信号肽序列。这些 发现强烈地表明蛇毒Kunitz/BPTI 蛋白酶抑制剂与神经毒性的类似物可能起源于 共同的祖先。 肥大细胞脱粒肽是从膜翅目昆虫的毒液中鉴别出的一个小肽家族，是一种具 有潜在的药物治疗作用的诱导活性分子（Xueqing Xu et al., 2006）。来源于蜂类的 缓激肽样的类似物vespakinin 家族是一种具有调节和激素功能的活性成分，与哺 乳动物和两栖动物的缓激肽类似（Nakajima T., 1984）。本研究对三种胡蜂的 毒液进行了一系列的活性检测，发现黑尾胡蜂的蜂毒对白色念珠菌Candida albicans 和金黄色葡萄球菌 Staphylococcus aureus 有抑制作用。凹纹胡蜂和黑尾 胡蜂的蜂毒具有微弱的磷酯酶A2 活性。通过凝胶过滤和反向高压液相色谱，没 有得到相关的活性组分。通过对三种胡蜂毒腺cDNA 文库的筛选，我们得到了2 条来源于黑尾胡蜂的核苷酸序列，Blast 分析表明，其中一条编码类似肥大细胞 脱粒肽，但未克隆到全长，序列比对结果显示其与来源于大胡蜂（Vespa magnifica） 的Mastoparan-like peptide 12c precursor（GenBank accession A0SPI0）的核苷酸序 列相似性达98％（Xueqing Xu et al., 2006）；另一条编码缓激肽类似物，命名为 Hw-bradykinin，序列比对结果显示其与来源于大胡蜂（Vespa magnifica）的 vespakinin-M precursor（GenBank accessionABG75944）的核苷酸相似率达96% (Zouhong Zhou et al., 2006)。

姚虻唾液腺三类抗血栓活性蛋白的结构和功能研究

血栓栓塞性疾病严重影响人类的健康，是导致死亡率最高的病因之一。在过去 的几十年中，已经开发了针对血液凝固、血小板激活和聚集、血栓溶解的不同步骤而 起作用的基础和临床药物，但是许多抗血栓药物经常被包括低血压、出血等系统性的 副作用所限制，因此，需要开发新型的更具潜力和特异性的抗血栓药物。 吸血节肢动物与宿主相互作用的分子机制研究是目前国际研究的热点之一，通过 该类研究可以发现大量的具有药用前景的先导分子和提供节肢动物控制策略。我们通 过生物化学、分子生物学以及药理学研究手段首次从中国特有的姚虻（Tabanus yao Macquart）唾液腺发现了同时具有水解纤维蛋白原和抑制血小板聚集的双功能的 丝氨酸蛋白酶Tablysin、纤维蛋白水解酶TY6和腺苷三磷酸双磷酸酶Tabapy等3个家 族的抗血栓活性成分。并研究了这3类因子在牛虻唾液腺中的分子多样性、它们的结 构基础及发挥抗血栓功能的作用机制，通过实验动物模型研究体内外抗血栓能力，深 入解析了牛虻作为传统抗血栓中药的物质基础，为发掘具有良好抗血栓功能的新型候 选药物分子，为传统活血化瘀中药牛虻的现代化开发提供了广阔的思路和打下了坚实 的基础。 研究表明，姚虻纤维蛋白原水解酶Tablysin为一种单链蛋白。其表观分子量为 27kDa。此酶为一种丝氨酸蛋白酶家族的新成员，其活性不受金属离子螯合剂EDTA 和还原剂DTT的影响。血浆蛋白酶抑制剂Aprotinin，α-macroglobulin能部分抑制该 酶活性。此酶适应的pH范围较广（pH 2.4-10.0），但对热变化不具很好的耐受性。 Edman降解法进行氨基酸测序分析发现，此酶的N-末端有封闭现象，后经Q-TOF质 谱分析，确定此酶的部分氨基酸序列。此外，我们成功构建了具有完整性的姚虻唾液 腺cDNA文库，获得2×106 pfu个重组子，进一步的筛选了Tablysin的编码基因。 对此酶的溶栓机制进行分析发现，其具有直接水解纤维蛋白原的活性，不具有纤 溶酶原激活剂的活性。此酶能明显地水解纤维蛋白原的α-链，而对β-链的水解活性较 低，不能水解γ链（α > β > γ）。此酶不能有效地水解纤维蛋白，不会水解层粘连蛋白 （Laminin）和纤维粘连蛋白（Fibronectin）等基质蛋白。不具有出血活性。进 一步探讨此酶的作用机制，发现其能以剂量依赖的方式抑制ADP诱导的血小板聚 集。利用流式细胞仪检测到该酶能与血小板膜糖蛋白受体GPIIb / IIIa结合，因此推测其可能是通过抑制血小板和纤维蛋白原结合的作用机制来抑制血小板 的聚集。 我们通过将目的基因连接到pET-32a+载体，并在大肠杆菌表达体系中得到 了高效表达。体外活性检测表明重组蛋白质与天然产物活性相当，用其检测了 其对角叉菜胶致小鼠尾静脉血栓模型体内血栓形成的影响， 实验结果表明 Tablysin具有明显的抗静脉血栓作用。该工作对有潜力开发成为新型单组分抗血栓 药物的姚虻活性蛋白进行了较为系统的理化性质研究，为该分子的进一步开发和研究 奠定了基础。 我们从姚虻唾液腺中分离纯化到一组具有水解纤维蛋白原α-链活性的酶， 命名为TY6家族。对TY6的生化性质进行研究，表明此酶为一种单链的丝氨酸蛋白 酶，其表观分子量为27 kDa，其活性不受金属离子螯合剂EDTA的影响，但能被PMSF 所抑制。Molish反应显示为阴性，说明此酶不是一种糖蛋白。从姚虻唾液腺cDNA 文库中克隆得到其编码序列，发现该酶家族的编码基因在一级结构上表现出丰 富的多样性。通过Western blotting检测到其能与牛虻叮咬后过敏患者血清特异性IgE 结合。推测该基因的多样性是吸血昆虫适应吸血寄生生活而采取的进化策略。 该工作为牛虻唾液腺抗血栓功能基因的继续筛选和分析奠定了基础，并为牛虻的生物 防治提供了思路和对策。 我们从姚虻唾液腺中分离纯化到一个具有水解ADP活性的酶（Apyrase）， 命名为Tabapy。活性检测发现Tabapy具有明显的水解ADP的活性，并能以剂量 依赖的方式抑制ADP诱导的血小板聚集。通过Western blotting检测到Tabapy能与 牛虻叮咬后过敏患者血清特异性IgE结合。用PCR方法从姚虻唾液腺cDNA文库中 克隆得到编码序列，经BLAST分析表明，该酶与来源于斑虻唾液腺的血小板聚 集抑制剂Chrysoptin具有90％的序列相似性，并经过Q-TOF分析确证，有5个肽段 的氨基酸残基与该cDNA序列推导的多肽链匹配。该工作为研究吸血节肢动物 吸血生理及进一步研究Apyrase的结构和功能打下了基础。

STRUCTURAL DEFECTS AND THEIR ELECTRICAL-ACTIVITY IN GERMANIUM IMPLANTED SILICON

The electrical and structural characteristics of secondary defects in regrown amorphous layers formed in n-type Si(100) with a resistivity of 2 OMEGA cm and 6 OMEGA cm using Ge+ ions, has been studied. The amorphous layers with a thickness of 460 nm are formed by implantation of 1 x 10(15) Ge+ cm-2 at an energy of 400 keV. Both conventional furnace and rapid thermal annealing were used to regrow the amorphous layer and the residual defects have been characterised in terms of their concentration depth distribution and activation energies using C-V and DLTS. Structural information has been obtained from RBS and XTEM. By choosing suitable anneal conditions it is possible to eliminate extended defects, apart from a low concentration of end of range dislocation loops. However, a substantial population of electrically active point defects remain after simple low thermal budget anneals. In a sample implanted with 1 x 10(15) Ge+ cm-2 at 400 keV a region of deep donors approximately 460 nm from the surface is always present When the samples are annealed at higher temperatures (> 850-degrees the total deep donor concentration is reduced by one order of magnitude. Other electrically active defects not observable in the low (750-degrees-C) temperature annealed layers become apparent during anneals at intermediate temperatures.

Space-grown SI-GaAs and its application

A semi-insulating GaAs single crystal ingot was grown in a recoverable satellite, within a specially designed pyrolytic boron nitride crucible, in a power-travelling furnace under microgravity. The crystal was characterized systematically and was used in fabricating low noise field effect transistors and analogue switch integrated circuits by the direct ion-implantation technique. All key electrical properties of these transistors and integrated circuits have surpassed those made from conventional earth-grown gallium arsenide. This result shows that device-grade space-grown semiconducting single. crystal has surpassed the best. terrestrial counterparts. Studies on the correlation between SI-GaAs wafers and the electronic devices and integrated circuits indicate that the characteristics of a compound semiconductor single crystal depends fundamentally on its stoichiometry.

Effects and numerical analysis of argon gas flow on the oxygen concentration in Czochralski silicon single crystal growth

Argon gas, as a protective environment and carrier of latent heat, has an important effect on the temperature distribution in crystals and melts. Numeric simulation is a potent tool for solving engineering problems. In this paper, the relationship between argon gas flow and oxygen concentration in silicon crystals was studied systematically. A flowing stream of argon gas is described by numeric simulation for the first time. Therefore, the results of experiments can be explained, and the optimum argon flow with the lowest oxygen concentration can be achieved. (C) 2002 Elsevier Science B.V. All rights reserved.

Determination of the interdiffusion coefficients of liquid Zn and Sn using Ta/Zn-Sn/Si trilayers

In this paper we present a new method for measuring diffusion coefficients in liquid metals under convection-less conditions with solid/liquid-liquid/solid trilayer. The advantage of this kind of trilayer is that effects from gravity-induced convection and Marangoni-convection can be omitted, so that the diffusion coefficient is determined more accurately. The Ta/Zn-Sn/Si trilayer were prepared with a multi-target ion-beam sputtering deposition technique and annealed in an electric furnace under an argon atmosphere. The interdiffusion of liquid zinc and tin at 500 degrees degree C was investigated. The diffusion concentration profiles were determined by energy dispersive spectroscopy. The interdiffusion coefficients range from 1.0x10(-6)cm(2)/s to 2.8x10(-6)cm(2)/s, which is less than previous values measured by capillary reservoir technique under 1g-environment where various convection exist. The precise interdiffusion coefficients of liquid zinc and tin result from the removing of disturbances of various kinds of convection.

Semi-insulating GaAs grown in outer space

A semi-insulating GaAs single crystal ingot was grown in a recoverable satellite, within a specially designed pyrolytic boron nitride crucible, in a power-traveling furnace under microgravity. The characteristics of a compound semiconductor single crystal depends fundamentally on its stoichiometry, i.e. the ration of two types of atoms in the crystal. a practical technique for nondestructive and quantitative measuring stoichiometry in GaAs single crystal was used to analyze the space-grown GaAs single crystal. The distribution of stoichiometry in a GaAs wafer was measured for the first time. The electrical, optical and structural properties of the space-grown GaAs crystal were studied systematically, Device fabricating experiments prove that the quality of field effect transistors fabricated from direct ion-implantation in semi-insulating GaAs wafers has a close correlation with the crystal's stoichiometry. (C) 2000 Elsevier Science S.A. All rights reserved.

慢生型大豆根瘤菌GX201与固氮相关的putA、lrp基因的研究

该研究运用分子生物学方法，克隆并测定了慢生型大豆根瘤菌的putA、lrp基因序列，通过BLAST软件分析发现，lrp基因存在putA基因的上游且转录方向相反.将含有gus报告基因的转座子Tn5gusA5转座到以pLAFR3为载体的重组质粒pGXN300后，利用pLAFR3与pPHIJI质粒的不相容性建立了一套适合于慢生型大豆根瘤菌的转座子诱变体系，应用该体系诱变慢生型大豆根瘤菌GX201，成功地构建了putA、lrp基因的突变体GX20108和GX20120.根据已测定的慢生型大豆根瘤菌的putA、lrp基因序列，设计一对核苷酸引物，PCR扩增putA基因的调控调区，研究lrp基因与putA基因的相互作用机制，离体试验证明putA基因的启动子区存在一个与lrp基因相关蛋白结合区域.