Electrocatalytic oxidation of methanol at platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes

<正>The electrocatalytic oxidation of methanol at the platinum electrode modified with Eu-Fe cyanide-bridged binuclear complexes (Eu-Fe film) was investigated for the first time by cyclic voltammetry.Compared with the bare platinum electrode,the results showed that the modified electrode had excellent electrocatalytic activity for the oxidation of methanol;the oxidation peak potential shifted more negatively and the peak current increased about twenty times.The electrooxidation of methanol at the modified electrode with Eu-Fe cyanide-bridged binuclear complexes material exhibited the better tolerance capacity to poison of intermediate species;the peak current was proportional to the concentration of methanol in the range of 0.5-2.0mol/L (R~2 = 0.9991,n =7),which was a comparatively wider linear range.Moreover,based on the linear relationship between the peak current and the square root of scan rate,electrocatalytic oxidation process of methanol was confirmed to be a diffusion control process.Furthermore,according to the counting of electron transfer number(n_α) in the rate-limiting step and the slope of linear equation between acidity of electrolyte and the oxidation peak potential(E_p),the possible mechanism of the electrooxidation of methanol at the modified electrode was primarily discussed.     

少精、弱精不育症患者精液中微量元素含量的测定分析

用ICPOES法检测了54例男性少精、弱精不育者精液中Ca、Cd、Cu、Fe、Mg、Mn、Ni、Zn元素的含量,并对相关含量进行数据分析。结果表明,精液中微量元素含量的改变是影响精液质量的重要原因之一。     

光谱法研究CdSe/CdS/ZnS量子点与壳聚糖的复合

通过CdSe/CdS/ZnS量子点与壳聚糖之间的静电作用,用共混法制备了壳聚糖-CdSe/CdS/ZnS复合物.用荧光光谱、紫外-可见光谱、红外光谱对所得的壳聚糖-CdSe/CdS/ZnS复合物进行了表征.研究结果表明:壳聚糖-CdSe/CdS/ZnS复合物具有良好的光学性能.     

膦系阻垢剂阻碳酸钙垢机理的研究

在模拟循环水中, 通过静态阻垢实验研究了HEDP, PBTCA, ATMP和EDTMP对碳酸钙的阻垢性能, 在相同的加药浓度下(按物质的量浓度计)阻垢性能的强弱顺序为HEDP＞PBTCA＞ATMP＞EDTMP; 同时采用分子动力学方法, 模拟计算了阻垢剂负二价离子与方解石(104), (102), (202)和(113)面的相互作用. 结果表明: 阻垢剂分子中的膦酸基团和羧酸基团与碳酸钙中的Ca^2＋形成的离子键对吸附起到了主要作用, 同时阻垢剂与晶面间存在较弱的范德华力相互作用. 阻垢剂与各晶面的结合能强弱顺序为(113)≥(102)≥(202)＞(104); 分子中的羟基易与垢晶面形成氢键而加强阻垢效果; 羧基的位置不同对阻垢作用的影响不同. 将静态阻垢的实验结果与分子动力学模拟结果进行了相关性分析, 发现阻垢剂在(104)面和(102)面上的吸附对阻垢作用的贡献较大.     

Simple preparation of Mn–N-codoped titania photocatalyst with visible light response

Mn–N-codoped TiO₂ nanocrystal photocatalysts responsive to visible light were synthesized for the first time by a simple hydrothermal synthesis method. X-ray powder diffraction (XRD) measurement indicated that all the photocatalysts have an anatase crystallite structure, and that increase of the doping concentration had little effect on the structure and particle size. Compared to N-doped TiO₂, a shift of the absorption edge of Mn–N-codoped TiO₂ to a lower energy and a stronger absorption in the visible light region were observed. The Mn–N-codoped TiO₂ showed higher photocatalytic reactivity than undoped TiO₂ or N-doped TiO₂ for the photodegradation of rhodamine B (RhB) under visible light irradiation. The highest photocatalytic activity was achieved on 0.4 mol% Mn–N–TiO₂ calcined at 673 K.     

Electrophoretic sol–gel synthesis of SrBi<Subscript>2</Subscript>Ta<Subscript>2</Subscript>O<Subscript>9</Subscript> nanowires

We report the independent invention of perovskite ferroelectric nanowires strontium bismuth tantalate (SrBi₂Ta₂O₉, SBT). Electrophoretic sol–gel techniques have been used successfully. The morphology and structures are analyzed via SEM, TEM and XRD. SBT nanowires and nanoparticles filled template revealed 30 and 40 μm long, respectively. SBT are proved to be a single phase of orthorhombic perovskite structure. As it indicated, SBT nanowires has been crystallized at 700 °C. To minimize surface polarity, SBT nanowires oriented preferentially along the growing axis (c axis) by translation and rotation of atomic clusters of SBT.     

Amminelithium Amidoborane Li(NH3)NH2BH3: A New Coordination Compound with Favorable Dehydrogenation Characteristics

The monoammoniate of lithium amidoborane, Li(NH₃)NH₂BH₃, was synthesized by treatment of LiNH₂BH₃ with ammonia at room temperature. This compound exists in the amorphous state at room temperature, but at ?20 °C crystallizes in the orthorhombic space group Pbca with lattice parameters of a=9.711(4), b=8.7027(5), c=7.1999(1) Å, and V=608.51 ų. The thermal decomposition behavior of this compound under argon and under ammonia was investigated. Through a series of experiments we have demonstrated that Li(NH₃)NH₂BH₃ is able to absorb/desorb ammonia reversibly at room temperature. In the temperature range of 40–70 °C, this compound showed favorable dehydrogenation characteristics. Specifically, under ammonia this material was able to release 3.0 equiv hydrogen (11.18 wt %) rapidly at 60 °C, which represents a significant advantage over LiNH₂BH₃. It has been found that the formation of the coordination bond between ammonia and Li⁺ in LiNH₂BH₃ plays a crucial role in promoting the combination of hydridic B? H bonds and protic N? H bonds, leading to dehydrogenation at low temperature.     

Real‐Time Monitoring of Mass‐Transport‐Related Enzymatic Reaction Kinetics in a Nanochannel‐Array Reactor

To understand the fundamentals of enzymatic reactions confined in micro‐/nanosystems, the construction of a small enzyme reactor coupled with an integrated real‐time detection system for monitoring the kinetic information is a significant challenge. Nano‐enzyme array reactors were fabricated by covalently linking enzymes to the inner channels of a porous anodic alumina (PAA) membrane. The mechanical stability of this nanodevice enables us to integrate an electrochemical detector for the real‐time monitoring of the formation of the enzyme reaction product by sputtering a thin Pt film on one side of the PAA membrane. Because the enzymatic reaction is confined in a limited nanospace, the mass transport of the substrate would influence the reaction kinetics considerably. Therefore, the oxidation of glucose by dissolved oxygen catalyzed by immobilized glucose oxidase was used as a model to investigate the mass‐transport‐related enzymatic reaction kinetics in confined nanospaces. The activity and stability of the enzyme immobilized in the nanochannels was enhanced. In this nano‐enzyme reactor, the enzymatic reaction was controlled by mass transport if the flux was low. With an increase in the flux (e.g., >50 μL min^?1), the enzymatic reaction kinetics became the rate‐determining step. This change resulted in the decrease in the conversion efficiency of the nano‐enzyme reactor and the apparent Michaelis–Menten constant with an increase in substrate flux. This nanodevice integrated with an electrochemical detector could help to understand the fundamentals of enzymatic reactions confined in nanospaces and provide a platform for the design of highly efficient enzyme reactors. In addition, we believe that such nanodevices will find widespread applications in biosensing, drug screening, and biochemical synthesis.     

Dual-sensitive probe 1-imidazole-2-(5-benzoacridine)-ethanone for the determination of amines in environmental water using HPLC with fluorescence detection and online atmospheric chemical ionization-mass spectrometry identification

Dual-sensitive probe of 1-imidazole-2-(5-benzoacridine)-ethanone (IBAE) for the determination of free amines with fluorescence detection and online highly sensitive atmospheric chemical ionization-mass spectrometry identification (APCI-MS) has been developed. 2-(Benzoacridine)-5-acetic acid (BAAA) reacts with coupling agent N,N′-carbonyldiimidazole (CDI) to form a highly activated amide intermediate 1-imidazole-2-(5-benzoacridine)-ethanone (IBAE), which is dual-sensitive probe. The amide intermediate (IBAE) reacts preferably with amines in dimethylformamide (DMF) solvent to give the high yields of derivatives. IBAE-amine derivatives are not only sensitive to fluorescence but also to MS ionizable efficiency. The percent ionization δ values change from 0 to 57.32% in aqueous acetonitrile and from 0 to 62.14% in aqueous methanol. The relative standard deviations of the peak areas with fluorescence detection for each amine are <1.24% (40 ng/ml, n = 6). The fluorescence detection limits (at a signal-to-noise ratio of 3) are in the range of 0.15-0.50 ng/ml. The online APCI-MS detection limits are in the range of 2.07-8.51 ng/ml (at a signal-to-noise ratio of 3). Therefore, the facile IBAE intermediate derivatization allowed the development of a highly sensitive and specific method for the quantitative analysis of trace levels of amines in environmental water.     

A pH responsive electrochemical switch sensor based on Fe(notpH3) [notpH6 = 1,4,7-triazacyclononane-1,4,7-triyl-tris(methylene-phosphonic acid)

The electrochemistry of a macrocyclic metal complex Fe(notpH₃) [notpH₆ = 1,4,7-triazacyclononane-1,4,7-triyl-tris(methylene-phosphonic acid)] reveals that the protonation/deprotonation of the non-coordinated P-OH groups in Fe(notpH₃) affects its formal potential value (E⁰′) considerably. Plotting E⁰′ as function of solution pH gives a straight line with a slope of −585 mV pH⁻¹ in the pH range of 3.4-4.0, which is about ten times larger than the theoretical value of −58 mV pH⁻¹ for a reversible proton-coupled single-electron transfer at 20 °C. A sensitive pH responsive electrochemical switch sensor is thus developed based on Fe(notpH₃) which shows an “on/off” switching at pH ∼ 4.0.