Photoinduced hydrogen evolution with water soluble bisviologen linked zinc porphyrin and hydrogenase

Water soluble bisviologen linked zinc porphyrin (ZnP(C₄V_AC₄V_B)₄) was synthesized and characterized. The quenching processes of the photoexcited singlet state and triplet state of ZnP(C₄V_AC₄V_B)₄ were measured by using fluorescence lifetime and laser flash photolysis. The photoexcited singlet state of the zinc porphyrin was quenched by the bonded bisviologen. Photoinduced hydrogen evolution with ZnP(C₄V_AC₄V_B)₄ and hydrogenase was observed under steady state irradiation.     

钛基体中离子注入镍和钼的电催化活性

Grenness等发现,铂离子注入钨基体中,对H~+还原产生的电催化性能与纯铂相近,此后,Wolf等用离子注入和离子束混合技术制作了多种电极,其中Pt/RuO_2、Pt/C、Pt/WC电极用于H~+和O_2的电还原以及甲醇和甲酸的电氧化,其催化活性和稳定性均优于光滑的纯铂电极,目前,在其它方法制作的析氢电极材料中,最可能用于工业电解槽的为NiMo合金电极和复合Raney镍合金电极,本工作将镍和钼离子注入到钛基体中,研究了此电极在30 wt％KOH溶液中析氢电催化行为,并通过电子探针显微分析(EPMA)和X射线光电子能谱(XPS)分析,检测了离子注入电极的表面成分、注入元素的浓度分布及价态。     

The origin and evolution of repeated sequencesand introns

Because the origin of repeated sequences may date back to the appearance of the first genes and genomes on Earth, they must have been involved in the entire history of genome evolution. Repeated sequences are important components of the primitive genomes that would provide the basis for the origin of split genes. In this sense, introns existed in early genes, and both repeated sequences and introns have always had structural and evolutionary roles. The evolution of the composition of organic genomes may be unified in a general pattern. Nuclear (nucleoid) genomes, mitochondrial genomes, and chloroplast genomes would respectively have evolved according to two scenarios. The small genome scenario would be evolutionary paths in which repeated sequences and introns have been lost, while the large genome scenario would be evolutionary paths in which repeated sequences and introns have been retained and developed.     

高通量筛选策略在细胞色素P450单加氧酶定向进化中的应用

细胞色素P450单加氧酶具有催化活性混杂性的特点,可以催化多种氧化反应,因而在生物催化领域受到了极大的关注。然而P450单加氧酶往往存在催化活性低、稳定性差、区域和立体选择性不理想等问题,从而限制了其在生物催化领域的广泛运用。蛋白质定向进化的发展与运用为改善P450单加氧酶的催化性能提供了有效的途径,而一种高效的高通量筛选策略是保证酶蛋白定向进化成功实施的关键。本文综述了P450单加氧酶定向进化过程中高通量筛选策略的最新进展。     

Alkene epoxidation catalyzed by cytochrome P450 BM-3 139-3

We recently reported conversion of cytochrome P450 BM-3, a medium-chain (C₁₂-C₁₈) fatty acid monooxygenase, into a highly efficient alkane hydroxylase by directed evolution [Nat. Biotechnol. 2002, 20, 1135]. P450 BM-3 mutant 139-3 exhibited high activity towards a variety of fatty acid and alkane substrates, including C₃-C₈ alkanes. We report here that mutant 139-3 is also active on benzene, styrene, cyclohexene, 1-hexene, and propylene. Benzene is converted to phenol, while styrene is converted to styrene oxide. Propylene oxidation generates only propylene oxide, but cyclohexene oxidation produces a mixture of cyclohexene oxide (85%) and 2-cyclohexene-1-ol (15%), and 1-hexene is converted to the allylic hydroxylation product, 1-hexene-3-ol. Initial rates of NADPH oxidation for 139-3 in the presence of the substrates greatly (17- to >100-fold) surpass the wild-type in all cases. However, NADPH consumption is only partially coupled to product formation (14-79%). This cytochrome P450 epoxidation catalyst is a suitable starting point for further evolution to improve coupling and activity.     

Photocatalyst Materials for Water Splitting

Various photocatalyst materials developed by the group of the present author are described. Alkali and alkaline earth tantalates have arisen as a new group of photocatalyst materials for splitting of water into H₂ and O₂ under ultraviolet irradiation. They showed activities even without co-catalysts such as Pt, being different from titanate photocatalysts. When NiO co-catalysts were loaded on the tantalate photocatalysts, the photocatalytic activities were markedly increased. Among the tantalates, NiO/NaTaO₃ doped with La showed the highest activity. BiVO₄, AgNO₃, and TiO₂ co-doped with Cr and Sb photocatalysts showed high activities for O₂ evolution in the presence of a sacrificial reagent (Ag⁺) under visible light irradiation ( > 420 nm). Pt/SrTiO₃ co-doped with Cr and Sb or Ta, Pt/NaInS₂, and Pt/AgInZn₇S₉ photocatalysts showed high activities for H₂ evolution from aqueous solutions containing reducing reagents under visible light irradiation. Furthermore, Cu- or Ni-doped ZnS photocatalysts showed H₂ evolution activities even without co-catalysts such as Pt.     

温度与碱浓度对FeO_4~(2-)/FeO_2~-体系电化学行为的影响

研究了影响Fe(OH)3进行酸式电离反应的因素,在多种浓度和温度条件下的NaOH浓溶液中采用SnO2-Sb2O3/Ti电极,研究FeO42-/FeO2-体系的电化学氧化还原反应参数及其变化趋势,结果证实该体系发生电化学氧化还原反应的最佳碱溶液浓度范围为12~14 mol/L,最佳温度范围为295~315 K.阐明了在实验条件下FeO42-/FeO2-氧化还原体系中存在由FeO43-/FeO2-构成的氧化还原电对,而FeO42-不直接与FeO2-构成氧化还原电对;并给出了FeO42-/FeO2-氧化还原体系的Latim er图.     

INVESTIGATION OF STRUCTURE AND PROPERTIES FOR POLYMER SYSTEMS BASED ON DYNAMIC RHEOLOGICAL APPROACHES

The dynamic theological measurements have been a preferred approach to the characterization of the structure and properties for multi-component or multi-phase polymer systems, due to its sensitive response to changes of structure for these heterogeneous polymers. In the present article, recent progresses in the studies on dynamic theology for heterogeneous polymer systems including polymeric composites filled with inorganic particles, thermo-oxidized polyolefins, phaseseparated polymeric blends and functional polymers with the scaling and percolation behavior are reviewed, mainly depending on the results by the authors‘ group. By means of theological measurements, not only some new fingerprints responsible for the evolution of morphology and structure concerning these polymer systems are obtained, the corresponding results are also significant for the design and preparation of novel polymer-based composites and functional materials.     

放氢交叉偶联反应

过渡金属催化的脱氢偶联反应是一类高效的化学键构筑方式，但通常需要当量甚至过量的氧化剂以移除脱氢过程产生的电子及质子，其氧化剂残渣对环境有一定的污染.放氢交叉偶联（CCHE）反应摒弃了传统脱氢反应中当量氧化剂的使用，在温和条件下实现碳-氢或杂-氢键直接交叉偶联且唯一副产物为氢气，不仅避免了因原料或产物对氧化剂敏感而发生的副反应，而且在规模化生产中具有很高的附加值，是一种更加绿色的合成策略.本综述从放氢交叉偶联反应机理、化学键构筑类型以及反应延伸等角度归纳并介绍了近年来放氢交叉偶联反应的研究进展，并对该领域的发展前景进行了展望.