Nanobelts of semiconducting oxides

Ultralong beltlike (or ribbonlike) nanostructures (so-called nanobelts) were successfully synthesized for semiconducting oxides of zinc, tin, indium, cadmium, and gallium by simply evaporating the desired commercial metal oxide powders at high temperatures. The as-synthesized oxide nanobelts are pure, structurally uniform, and single crystalline, and most of them are free from defects and dislocations. They have a rectanglelike cross section with typical widths of 30 to 300 nanometers, width-to-thickness ratios of 5 to 10, and lengths of up to a few millimeters. The beltlike morphology appears to be a distinctive and common structural characteristic for the family of semiconducting oxides with cations of different valence states and materials of distinct crystallographic structures. The nanobelts could be an ideal system for fully understanding dimensionally confined transport phenomena in functional oxides and building functional devices along individual nanobelts.     

Hierarchically ordered oxides

Porous silica, niobia, and titania with three-dimensional structures patterned over multiple length scales were prepared by combining micromolding, polystyrene sphere templating, and cooperative assembly of inorganic sol-gel species with amphiphilic triblock copolymers. The resulting materials show hierarchical ordering over several discrete and tunable length scales ranging from 10 nanometers to several micrometers. The respective ordered structures can be independently modified by choosing different mold patterns, latex spheres, and block copolymers. The examples presented demonstrate the compositional and structural diversities that are possible with this simple approach.     

利用Cre/lox重组系统建立番茄基因工程雄性不育恢复系

 【目的】利用Cre/lox重组系统具有的重组删除特性建立番茄工程恢复系,特异删除F1中的雄性不育基因恢复其育性。【方法】将TA29-Barnase雄性不育基因表达盒置于两个同向lox位点之间并与NPTⅡ基因、Bar基因融合后获得植物表达载体pBinBarloxTABn,转化番茄获得雄性不育转基因植株。Cre基因在 CaMV35S启动子的驱动下转入番茄获得工程恢复系。两者在开花时进行杂交,利用Cre重组酶删除F1中的TA29-Barnase不育基因表达盒使育性恢复。【结果】利用NPTⅡ作为转化筛选标记基因获得了番茄雄性不育转基因植株。转基因植株中的Bar基因能正常表达,真叶叶盘在含PPT 3 mg?L-1（phosphinothricin）分化培养基上能分化愈伤组织及芽;真叶具有抗PPT 20 mg?L-1浓度以上的能力。获得的TA29-Barnase转基因植株表现雄蕊退化、无花粉产生或产生少量形状畸形且无生活力的花粉。雄性不育植株自花授粉不能坐果,用非转基因保持系花粉授粉后,果实正常膨大结籽,杂交后代对除草剂Basta的抗性按1﹕1分离。不育植株与Cre转基因工程恢复系杂交后,果实也正常膨大结籽。对不育植株与Cre转基因工程恢复系杂交后代进行分子检测,结果发现同时含Bar 基因和Cre基因F1植株中的TA29-Barnase雄性不育基因被精确删除。TA29-Barnase基因删除植株育性被恢复,能正常开花结果。【结论】利用Cre/lox重组系统建立的Cre工程恢复系成功将番茄F1代中的不育基因删除,恢复了 F1的育性。该研究结果为植物基因工程雄性不育系的育性恢复提供了一条新的途径。     

沼液的工程化处置技术

探讨了沼液的低成本的自然工程化净化处理、高成本的工程化净化处理以及高附加值的开发性工程化净化处理工艺,并分析各自的利弊。     

转基因作物安全性研究进展

概述了国内外转基因作物环境安全性中的生态竞争性，生殖隔离距离，基因污染，对非靶生物的影响和新病原菌产生的可能性以及食品安全性中的毒性，过敏反应和对抗生素的抗药性等问题。并简述了基因工程作物安全性评估的原则。方法。     

Radiation tolerance of complex oxides

The radiation performance of a variety of complex oxides is predicted on the basis of a material's propensity to accommodate lattice point defects. The calculations indicate that a particular class of oxides possessing the fluorite crystal structure should accept radiation-induced defects into their lattices far more readily than a structurally similar class of oxides based on the pyrochlore crystal structure. Preliminary radiation damage experiments substantiate the prediction that fluorites are inherently more radiation resistant than pyrochlores. These results may permit the chemical durability and radiation tolerance of potential hosts for actinides and radioactive wastes to be tailored.     

鱼用基因工程疫苗研究进展

疫苗是目前控制鱼类病害最经济有效的方式。免疫学及生物工程的迅速发展极大地促进了鱼类基因工程疫苗的研究。基因工程疫苗克服了传统疫苗的一些缺陷和不足，显示出巨大的应用前景，已成为国内外水产养殖业的研究热点，近年对鱼用基因工程疫苗的研究已取得较大进展，但鱼用基因工程疫苗在研究和应用过程中也面临着急需解决的若干问题。     

鱼用基因工程疫苗的研究概况

鱼病的化学药物防治会导致水质恶化、水产品药物残留超标或病原体耐药性增强等弊端.随着鱼类免疫学研究以及分子生物学技术的发展,鱼用基因工程疫苗的研究受到了广泛关注.系统地解析与梳理了鱼用基因工程疫苗发展的背景、意义及疫苗类型和国内外的研究与应用现状,明确现阶段我国鱼用基因工程疫苗发展面临的挑战并提出相应的发展建议,旨在为未...     

Superconducting interfaces between insulating oxides

At interfaces between complex oxides, electronic systems with unusual electronic properties can be generated. We report on superconductivity in the electron gas formed at the interface between two insulating dielectric perovskite oxides, LaAlO3 and SrTiO3. The behavior of the electron gas is that of a two-dimensional superconductor, confined to a thin sheet at the interface. The superconducting transition temperature of congruent with 200 millikelvin provides a strict upper limit to the thickness of the superconducting layer of congruent with 10 nanometers.     

Orbital physics in transition-metal oxides

An electron in a solid, that is, bound to or nearly localized on the specific atomic site, has three attributes: charge, spin, and orbital. The orbital represents the shape of the electron cloud in solid. In transition-metal oxides with anisotropic-shaped d-orbital electrons, the Coulomb interaction between the electrons (strong electron correlation effect) is of importance for understanding their metal-insulator transitions and properties such as high-temperature superconductivity and colossal magnetoresistance. The orbital degree of freedom occasionally plays an important role in these phenomena, and its correlation and/or order-disorder transition causes a variety of phenomena through strong coupling with charge, spin, and lattice dynamics. An overview is given here on this "orbital physics," which will be a key concept for the science and technology of correlated electrons.     

多功能农药降解基因工程菌剂保藏条件研究

应用多功能农药降解基因工程菌修复农药污染潜力巨大,但由于微生物菌剂的保存一直是个难题,直接影响到微生物菌剂的应用.本实验室构建的基因工程菌属于鞘胺醇单胞菌属,易受到污染而消亡,液态菌剂保藏效果不理想,因此找到一种吸菌量大,并能增加细胞密度和保持菌种存活力的载体显得尤为迫切.通过单一载体吸菌量的测定、不同剂型保藏试验、不同接种量保藏试验、保护剂选择试验等方法研究了不同剂型对微生物菌剂活菌数量及保存期的影响.结果表明草炭是一种优良的同体载体--吸菌量大,可达1011 CFU·g-1,并能促进工程菌的生长,109CFU·g-1接种量接种后120 d仍能使工程菌数量维持在109CFU·g-1水平.通过盆钵试验表明长期保藏后的微生物菌剂能在25 d内将甲基对硫磷和呋喃丹完全降解,应用效果不受保藏影响.本实验为工程菌剂的保存和应用提供了理论参考.     

植物抗病毒基因工程的策略和机制

对20世纪90年代以来两大类来源尤其是以病原物抗性基因为来源的植物抗病毒基因工程研究进展进行了综述，并讨论了各种病毒基因提供抗性的特点、局限性及可能的机制。     

苏云金芽胞杆菌ICP基因工程菌的研究进展

综述了近年来国内外利用杀虫细菌苏云金杆菌ＩＣＰ基因构建工程菌，包括植物根际定居菌、植物疫苗、重组杀蚊蓝细菌和杆状病毒Ｂｔ重组菌等研究的历程及现状、成功的范例及存在问题．文中亦讨论了该研究领域的应用前景．     

沉积物中人工纳米颗粒对BDE-47生态毒性的影响

为评价淡水沉积物中人工纳米颗粒对持久性有机污染物生态毒性的影响,以底栖动物铜锈环棱螺为受试生物,采用沉积物慢性生物测试研究了非毒性浓度的不同管径多壁碳纳米管(MWCNTs)和两种金属氧化物纳米颗粒(三氧化二铝纳米颗粒Al₂O₃-NPs和二氧化钛纳米颗粒TiO₂-NPs)存在条件下不同浓度2, 2', 4, 4'-四溴联苯醚(BDE-47)对铜锈环棱螺肝胰脏超氧化物歧化酶(SOD)、谷胱甘肽-S-转移酶(GST)活性和丙二醛(MDA)含量的影响.结果表明,两种管径大小的MWCNTs不影响低浓度(100 ng·g^-1) BDE-47对铜锈环棱螺的毒性,但显著降低较高浓度(500、2000 ng·g^-1)BDE-47对铜锈环棱螺的毒性,小管径MWCNTs对BDE-47毒性的影响稍大于大管径MWCNTs;Al₂O₃-NPs和TiO₂-NPs对低浓度BDE-47的毒性没有影响,但显著增加较高浓度BDE-47对铜锈环棱螺的毒性,TiO₂-NPs对BDE-47毒性的影响略大于非毒性浓度Al₂O₃-NPs.这表明,沉积物中不同种类和类型的纳米颗粒对有机污染物生态毒性的影响存在明显差异.     

R-工程菌表达产物酯酶 B1的固定化及其降解特性

将抗性库蚊的解毒酶基因克隆到大肠杆菌中,得到R-工程菌,该工程菌的表达产物酯酶B1能高效降解有机磷、有机氯、氨基甲酸酯、菊酯等4大类农药。本研究将重组质粒pR L-B1转入大肠杆菌D H5α,以5%的接种量转接到LB液体培养基中,37℃振荡培养13h。超声波破碎工程菌,20%～80%的硫酸铵沉淀粗提后,采用海藻酸钙将R-工程菌表达产物酯酶B1进行固定化,并测定了固定化酶对其特异性底物α-乙酸萘酯的降解特性。结果表明,酶的最佳固定化浓度为0.15g·L-1,最佳固定化时间为12h,固定化酶最佳反应pH为7.0～7.5,最适温度为40℃,固定化酶显示出很高的热稳定性和重复使用稳定性,在常温下其半衰期为12d,利用双倒数法确定固定化酶的Km为1.8×10-3m m ol·L-1,Vm ax为1.45×104U·g-1,固定化酶的K m是液态酶(1.35×10-3m m ol·L-1)的1.33倍,V m ax只有液态酶(2.7×104U·m L-1)的近1/2。利用气相色谱测得其对有机磷农药对硫磷(1605)的降解率在30m in内达53.8%。     

组成型脱硫工程菌的构建及其脱硫性能分析

[目的]研究组成型脱硫工程菌的构建及其脱硫性能。[方法]以专一性脱硫菌德氏假单胞菌Pseudomonas delafieldii R-8为出发菌株,将该菌的脱硫质粒中的脱硫基因dszABC和组成型gap基因启动子克隆到表达载体pPR9TT中,获得的组成型重组质粒pRT-C后电转化R-8-0菌,得到了组成型工程菌R-8-C,并对其脱硫性能进行了比较研究。[结果]R-8-C菌在含0.10 mmol/L Na2SO4的BSM培养基中仍然具有较高脱硫活性,在72 h内,是以二苯并噻吩(DBT)为唯一硫源时R-8脱硫活性的93%;而对照组(即原始菌R-8)几乎不能脱硫。以DBT为唯一硫源时,在不同生长时期内,R-8-C菌生长细胞的脱硫活性均高于R-8菌,且在24 h内,R-8-C菌的脱硫活性约为R-8菌的1.3倍。[结论]该研究为进一步了解脱硫基因调控机制及构建高活性脱硫工程菌奠定了基础。