分子氧为氧化剂磷钒酸盐为催化剂超深度氧化脱除柴油中的二苯并噻吩

一种“双帽Keggin型”磷钒酸盐在温和的反应条件下以分子氧为氧化剂氧化二苯并噻吩至二苯并噻吩砜的反应中表现出很高的催化活性. 用溶剂萃取或者选择吸附等方法可轻易地将反应产生的二苯并噻吩砜从油品中除去. 这提供了一种新型的分子氧为氧化剂的超深度氧化脱硫方法.     

Surface-Polarity-Induced Spatial Charge Separation Boosts Photocatalytic Overall Water Splitting on GaN Nanorod Arrays

Photocatalytic overall water splitting has been recognized as a promising approach to convert solar energy into hydrogen. However, most of the photocatalysts suffer from low efficiencies mainly because of poor charge separation. Herein, taking a model semiconductor gallium nitride (GaN) as an example, we uncovered that photogenerated electrons and holes can be spatially separated to the nonpolar and polar surfaces of GaN nanorod arrays, which is presumably ascribed to the different surface band bending induced by the surface polarity. The photogenerated charge separation efficiency of GaN can be enhanced significantly from about 8 % to more than 80 % via co-exposing polar and nonpolar surfaces. Furthermore, spatially assembling reduction and oxidation cocatalysts on the nonpolar and polar surfaces remarkably boosts photocatalytic overall water splitting, with the quantum efficiency increased from 0.9 % for the film photocatalyst to 6.9 % for the nanorod arrays photocatalyst.     

基于苯乙烯和苯并噻二唑共聚场效应发光高分子材料的设计合成及性能研究

共轭高分子材料由于其优异的光电性能和可溶液加工等特性在有机光电器件中具有重要应用.本工作采用Stille偶联和Suzuki聚合反应,合成了两个由经典发光基元苯乙烯片段和共轭吸电子结构基元苯并噻二唑共聚的高分子材料聚（1,2-双（2,5-双（异辛氧基）亚苯基亚乙烯基-2,1,3-苯并噻二唑））（PVBT）和聚（1,2-双（2,5-双（正辛氧基）亚苯基亚乙烯基-2,1,3-苯并噻二唑））（nPVBT）.通过凝胶渗透色谱（GPC）、元素分析及差式扫描量热法（DSC）对PVBT和nPVBT两种高分子材料的结构及热稳定性进行表征,结果表明它们均具有良好的热稳定性,分解温度约380℃.由于烷氧基链的存在,两个材料具有良好的溶解性及成膜加工性.PVBT和nPVBT均表现出优异的发光特性,最大发射波长在590~605 nm范围,溶液下荧光量子产率为23%~35%,固态薄膜下量子产率为12%~20%.以这两个高分子材料薄膜作为活性层,所制备的顶栅-底接触型有机场效应晶体管器件显示出典型的p型电荷传输性能,空穴迁移率可达1.1×10^-4 cm²·V^-1·s^-1,开关比为10³~10⁴.本研究为发展高性能光电集成高分子材料提供了新思路,有望推动有机光电集成器件的研究.     

Two-dimensional Molecular Phase Transition of Alkylated-TDPB on Au(111) and Cu(111) Surfaces

The derivatives of aromatic cores bearing alkyl chains with different lengths are of potential interest in on-surface chemistry, and thus have been widely investigated both at liquid-solid interfaces and in vacuum. Here, we report on the structural evaluation of self-assembled 1,3,5-tri(4-dodecylphenyl)benzene(TDPB) molecules with increased molecular coverages on both Au(111) and Cu(111) surfaces. As observed on Au(111), rhombic and herringbone structures emerge successively depending on surface coverage. In the case of Cu(111), the same process of phase conversion is also observed, but with two distinct structures. In comparison, the self-assembled structures on Au(111) surface are packed more densely than that on Cu(111) surface under the same preparation conditions. This may fundamentally result from the higher adsorption energy of TDPB molecules on Cu(111), restricting their adjustment to optimize a thermodynamically favorable molecular packing.     

The Effect of Enantiomer Elution Order on the Determination of Minor Enantiomeric Impurity in Ketoprofen and Enantiomeric Purity Evaluation of Commercially Available Dexketoprofen Formulations

In a recent study, opposite enantiomer elution order was observed for ketoprofen enantiomers on two amylose-phenylcarbamate-based chiral columns with the same chemical composition of the chiral selector but in one case with coated while in the other with an immobilized chiral selector. In the present study, the influence of this uncommon effect on method validation parameters for the determination of minor enantiomeric impurity in dexketoprofen was studied. The validated methods with two alternative elution orders for enantiomers were applied for the evaluation of enantiomeric impurity in six marketed dexketoprofen formulations from various vendors. In most of these formulations except one the content of enantiomeric impurity exceeded 0.1% (w/w).     

Natural Melanin Nanoparticle‐decorated Screen‐printed Carbon Electrode: Performance Test for Amperometric Determination of Hexavalent Chromium as Model Trace

A biosensor was prepared with natural melanin nanoparticles (MNP) decorated on a screen‐printed carbon electrode (SPCE). Hexavalent chromium was selected as a well‐known heavy metal ion to be detected for testing the performance of novel biosensor. Natural MNP was extracted from cuttlefish (Sepia officinalis) ink. Surface decoration of SPCEs with MNP was performed by two different methods. The first one was layer‐by‐layer assembly (LBL‐A) for different cycle times(n). In the second one, plasma treatment of SPCE incorporated with evaporation‐induced self‐assembly (EI‐SA) techniques including different incubation times in MNP solutions. The performance of both modified SPCEs were tested for amperometric detection of Cr(VI) in various water samples, and peak reduction of Cr(VI) was determined at 0.33 V. Amperometric results showed wide linear ranges of 0.1–2 μM and 0.1–5 μM of Cr(VI) for SPCEs modified with 14n‐LBL‐A and 12h‐EI‐SA, respectively. The sensitivities of SPCEs modified with 14n‐LBL‐A and 12h‐EI‐SA techniques were 0.27 μA μM^?1 and 0.52 μA μM^?1, respectively. In addition, both modified SPCEs selectively detected Cr(VI) in a model aqueous system composed of certain other heavy metals and minerals, and tap and lake water samples. The LOD and LOQ values for 12h‐EI‐SA were 0.03 μM and 0.1 μM, respectively. This showed that MNP‐modified‐SPCEs generated via EI‐SA techniques have the potential to be an alternative to conventional detection methods such as ICP‐MS.     

不同烟草生物质热解释放致香物质的研究

采用烟叶和烟梗为原料,使用热裂解气相色谱法对烟草的燃烧时间、燃烧温度进行控制,精确模拟实际烟草致香物质释放环境,精确捕获、并半定量物质,从而在实验室模拟、分析、研究烟草燃烧物中致香物质的组成和特点。研究分别考察了两种生物质在500℃、550℃下释放的致香物质组成。结果表明,烟梗、烟叶中元素组成中硫、氮两种元素含量低,而C/H比值两种烟草生物质均较高。两个热解温度下烟叶的热解产物中致香物质的含量均明显高于烟梗。升高热解温度均有利于获得更高相对含量的热解成分。烟叶热解产物中烯烃类物质相对含量比烟梗中多,而烟梗热解产物中酚类物质含量比烟叶中多。提高热解温度有利于酮类致香物质含量产生。     

Understanding energetic disorder in electron-deficient-core-based non-fullerene solar cells

Recent advances in material design for organic solar cells(OSCs) are primarily focused on developing near-infrared nonfullerene acceptors, typically A-DA′D-A type acceptors(where A abbreviates an electron-withdrawing moiety and D, an electron-donor moiety), to achieve high external quantum efficiency while maintaining low voltage loss. However, the charge transport is still constrained by unfavorable molecular conformations, resulting in high energetic disorder and limiting the device performance. Here, a facile design strategy is reported by introducing the "wing"(alkyl chains) at the terminal of the DA′D central core of the A-DA′D-A type acceptor to achieve a favorable and ordered molecular orientation and therefore facilitate charge carrier transport. Benefitting from the reduced disorder, the electron mobilities could be significantly enhanced for the"wing"-containing molecules. By carefully changing the length of alkyl chains, the mobility of acceptor has been tuned to match with that of donor, leading to a minimized charge imbalance factor and a high fill factor(FF). We further provide useful design strategies for highly efficient OSCs with high FF.     

Influence of the Acetamide from Acetonitrile Hydrolysis in Acid-Contained Mobile Phase on the Ultraviolet Detection in High Performance Liquid Chromatography

The paper presents the influence of acetamide on ultraviolet detection after generation of acetonitrile by hydrolysis in the presence of trifluoroacetic acid in the HPLC mobile phase. The acetonitrile, with added varying contents of trifluoroacetic acid and water, was determined by GC–MS at various times. The results showed that the concentration of acetamide increased approximately linearly with time. Using a mixed standard sample solution and a model mobile phase of acetonitrile-water-tri-fluoroacetic acid (25:75:0.3, v/v) after 0, 24 and 48 h, the influence of the hydrolyzate acetamide on HPLC detection was investigated at the wavelength of 205–220 nm. The results showed that the limit of detection (LOD) of standard sample lost about 30 % after the mobile phase was placed 48 h. It is suggested that the acid-containing mobile phase was placed no more than 24 h for HPLC trace analysis at the wavelength of 205–220 nm.

     

低起始温度的线性升温热处理对直拉硅中氧沉淀的影响

研究了直拉硅片从不同的温度线性升温(Ramping)到750℃，然后在750℃退火64 h过程中的氧沉淀行为. 结果表明，Ramping对硅片中氧沉淀的形成有明显的促进作用，且起始温度越低促进作用越强. 这是因为在Ramping处理中，低温(450—650℃)热处理阶段氧的扩散速率显著增强，促进了氧沉淀核心的形成，且较低的Ramping升温速率有利于氧沉淀核心的稳定和继续长大. 进一步的实验结果还表明，低起始温度的Ramping处理可应用于硅片的内吸杂工艺，能促进氧沉淀的生成提高硅片的内吸杂能力，减少热预