Reactivity of the gold/water interface during selective oxidation catalysis

The selective oxidation of alcohols in aqueous phase over supported metal catalysts is facilitated by high-pH conditions. We have studied the mechanism of ethanol and glycerol oxidation to acids over various supported gold and platinum catalysts. Labeling experiments with (18)O(2) and H(2)(18)O demonstrate that oxygen atoms originating from hydroxide ions instead of molecular oxygen are incorporated into the alcohol during the oxidation reaction. Density functional theory calculations suggest that the reaction path involves both solution-mediated and metal-catalyzed elementary steps. Molecular oxygen is proposed to participate in the catalytic cycle not by dissociation to atomic oxygen but by regenerating hydroxide ions formed via the catalytic decomposition of a peroxide intermediate.     

超临界水氧化法去除偏二甲肼条件的研究

在压力24-30 MPa和温度400-500℃条件下,以Cu2为催化剂、H2O2为氧化剂、在连续流管式 反应器中进行了催化超临界水氧化偏二甲肼试验,研究温度、压力、停留时间和Cu2质量浓度对偏二甲肼氧化降解 的影响结。结果表明,在超临界水中偏二甲肼能被有效去除。偏二甲肼的去除率随反心温度和压力的升高、停留时间 的延长和Cu4质量浓度的增大而提高。当压力为30MPa、温度为450℃、停留时间为3．9 s、Cu-质量浓度为15 mg/L时,COD去除率可达97．8%。     

Green, catalytic oxidation of alcohols in water

Alcohol oxidations are typically performed with stoichiometric reagents that generate heavy-metal waste and are usually run in chlorinated solvents. A water-soluble palladium(II) bathophenanthroline complex is a stable recyclable catalyst for the selective aerobic oxidation of a wide range of alcohols to aldehydes, ketones, and carboxylic acids in a biphasic water-alcohol system. The use of water as a solvent and air as the oxidant makes the reaction interesting from both an economic and environmental point of view.     

高级氧化法在水处理领域中的应用研究

阐述了Fenton法、O3氧化法、光化学氧化法、电化学氧化法、湿式氧化法、超临界水氧化法、超声波氧化法等不同高级氧化技术的反应原理及在水处理领域中的研究现状,并探讨了不同高级氧化技术在应用过程中存在的问题及今后的研究方向.     

Surface oxidation: a major sink for water on Mars

Surface oxidation irreversibly removes both oxygen and hydrogen from the martian atmosphere at a rate of 10(8) to 10(11) per square centimeter per second. This rate corresponds to a net loss of 10(25) to 10(28) per square centimeter (10(2) to 10(5) grams per square centimeter) of H(2)O, if it is assumed that the loss rate is uniform over geologic time. Heretofore, exospheric escape was considered to be the principal irreversible sink for H(2)O, but the loss rate was estimated to be only 10(8) per square centimeter per second. It is possible that surface oxidation may have had a minor effect on the supply of H(2)O in the regolith and polar caps.     

Asymmetric catalysis of the transannular Diels-Alder reaction

Transannular chemical reactions are unparalleled in their ability to generate high degrees of stereochemical and architectural complexity in a single transformation. However, the successful application of this approach in synthesis depends on the ability to predict and control the outcome of the transannular reaction. Use of a chiral catalyst in this context represents an attractive, yet unused, strategy. This report describes a catalytic, asymmetric transannnular Diels-Alder (TADA) reaction that affords polycyclic products in high enantiomeric excess. This catalyst system can also alter the inherent diastereoselectivity of cyclizations with substrates containing chiral centers. Additionally, the catalytic enantioselective TADA has been used as the key step in a total synthesis of the sesquiterpene 11,12-diacetoxydrimane; this route may provide a general approach to the polycyclic carbon framework shared by many terpene natural products.     

Stereochemical course of catalysis by the Tetrahymena ribozyme

The group I intron from Tetrahymena catalyzes phosphodiester transfer reactions on various RNA substrates. A modified RNA substrate with a phosphorothioate group in one stereoisomeric form at the site of reaction was synthesized in order to determine the stereochemical course of an RNA-catalyzed reaction. The reaction product was digested with a stereospecific nuclease to determine the configuration of the product phosphorothioate. The reaction occurs with inversion of configuration at phosphorus, implying an in-line pathway for the reaction.     

酵母菌生物接触氧化工艺处理皂素生产废水研究

以酵母菌作为特定微生物,采用生物接触氧化工艺处理皂素生产废水,对其工艺参数进行了优选 研究。结果表明,生物接触氧化工艺中以酵母菌为优势菌群,当温度为28-30 C,进水化学需氧量(COD)为2 710 -9 200 mg／L,pH值为4．5-5．5,溶解氧为4．5 mg／L,水力停留时间(HRT)为12 h时,COD去除率超过70％, 反应出水回收的酵母干菌稳定在8．3g／L以上,且产量随进水有机物浓度升高而上升。     

超临界水氧化压力条件对剩余污泥处理效果的影响

在不同压力条件下,采用超临界水氧化法处理剩余污泥。对化学需氧量(COD)、总氮、氨氮的去除效果及总磷、正磷酸盐的变化规律进行了研究,并对处理后的固体产物进行了分析。结果表明,随着反应压力增大,反应后出水水质较好,COD去除效果提高,COD去除率最高为95.80%;随反应压力增大,总氮去除效果提高,总氮去除率最高为85.27%;总氮主要以游离氨和铵离子形式存在,氨氮去除率最高为50.81%。反应压力在27 MPa时,液相中正磷酸盐的转化率达到97.23%。反应后污泥中的磷元素主要以磷酸盐形式存在于污泥残渣中。处理后残渣主要还包含O、Si、Al、Fe,P,S和Ca。超临界水氧化技术处理剩余污泥具有较好的无害化和减量化效果。     

抗克百威单克隆抗体的研制

用与牛血清蛋白(BSA)交联的克百威人工抗原(BFNB-BSA)免疫的BALB/C鼠脾细胞与SP2/0鼠骨髓瘤细胞融合,经筛选、克隆,得到1株能稳定分泌克百威抗体的单克隆细胞株(1E8)。鉴定结果表明,1E8的抗体类型及亚类均为IgG1,其轻链为κ链。制备单克隆抗体腹水,腹水的间接ELISA(酶联免疫吸附分析)效价在1×10-6以上。直接ELISA线性回归方程为y=15.70lg(x)-5.879 5,r2=0.990 4,抑制中浓度IC50=35.1μg.L-1,最低检测限IC20=5.2μg.L-1。该单克隆抗体与克百威特异性结合反应的50%抑制质量浓度为35.1μg.L-1。除丁硫克百威以外与其他克百威结构类似物无交叉反应。     

鼠源单克隆抗体人源化研究进展

杂交瘤技术诞生以来,鼠源单克隆抗体为人类疾病的研究起到了重大的推动作用,而鼠源单克隆抗体用于疾病的治疗时却有严重的不足,单克隆抗体人源化已是当前研究的热点。对单克隆抗体人源化的有关实验研究进展进行了综述。     

Surface science and catalysis

During the last 20 years, surface scientists have developed a variety of techniques that make it possible to study, on the molecular level, the structure, composition, and chemical bonding in the surface monolayer. Both single-crystal model catalysts and real catalyst systems that are active in important chemical processes have been investigated by a combination of ultrahigh-vacuum surface science techniques and high-pressure kinetic techniques in an effort to determine the relation between the structure and composition of the surface and the rates of reaction and selectivities. The structure of the atomic surface, a strongly adsorbed overlayer, and the oxidation states of surface atoms are the important molecular features of an active catalyst. As a consequence of modern surface science, the design and preparation of catalysts has developed from an art into a high technology.     

Enzyme dynamics during catalysis

Internal protein dynamics are intimately connected to enzymatic catalysis. However, enzyme motions linked to substrate turnover remain largely unknown. We have studied dynamics of an enzyme during catalysis at atomic resolution using nuclear magnetic resonance relaxation methods. During catalytic action of the enzyme cyclophilin A, we detect conformational fluctuations of the active site that occur on a time scale of hundreds of microseconds. The rates of conformational dynamics of the enzyme strongly correlate with the microscopic rates of substrate turnover. The present results, together with available structural data, allow a prediction of the reaction trajectory.