Electrochemical dehydrogenative N–H/N–H coupling reactions

The N–N bond is present in many important organic compounds, such as hydrazines, pyrazoles, azos, etc. Many methods based on transition metal catalyzed N–N coupling or functionalization of hydrazine have been reported for the synthesis of N–N containing organic compounds. In recent years, electrochemical dehydrogenative N–H/N–H coupling has become a powerful tool for the construction of N–N bearing organic compounds. The electrochemical methods employ electrons as traceless redox reagents instead of chemicals and produce hydrogen as the only byproduct. In this review, we summarize the recent advances in the electrochemical dehydrogenative N–H/N–H coupling reactions with focus on the mechanistic insights and synthetic applications of these transformations.     

Pd0-Catalyzed Asymmetric Carbonitratation Reaction Featuring an H-Bonding-Driven Alkyl−PdII−ONO2 Reductive Elimination

Reductive elimination of alkyl−Pd^II−O is a synthetically useful yet underdeveloped elementary reaction. Here we report that the combination of an H-bonding donor [PyH][BF₄] and AgNO₃ additive under toluene/H₂O biphasic system can enable such elementary step to form alkyl nitrate. This results in the Pd⁰-catalyzed asymmetric carbonitratations of (Z)-1-iodo-1,6-dienes with (R)-BINAP as the chiral ligand, affording alkyl nitrates up to 96 % ee. Mechanistic studies disclose that the reaction consists of oxidative addition of Pd⁰ catalyst to vinyl iodide, anion ligand exchange between I⁻ and NO₃⁻, alkene insertion and S_N2-type alkyl−Pd^II−ONO₂ reductive elimination. Evidences suggest that H-bonding interaction of PyH⋅⋅⋅ONO₂ can facilitate dissociation of O₂NO⁻ ligand from the alkyl−Pd^II−ONO₂ species, thus enabling the challenging alkyl−Pd^II−ONO₂ reductive elimination to be feasible.     

大黄鱼仿生态分阶段养殖新模式的构建及问题探讨

根据野生大黄鱼的洄游规律、生态习性, 采用人工手段的移动, 来满足其生活史中赖以生存的自然条件, 构建大黄鱼养殖全过程仿生态分阶段养殖新模式. 新模式实施结果, 养殖优势明显, 尤其是达到了拟野生的品质和口感, 经济效益极为显著. 本文通过对新模式产生的背景、新模式发展的理论基础、新模式的生产环节的构成及问题探讨等四个方面对大黄鱼仿生态分阶段养殖新模式进行全面的论述, 为这种模式的健康发展和推广提供一些理论依据.     

Effects of Pellet Characteristics on L-Lactic Acid Fermentation by R. oryzae: Pellet Morphology,Diameter, Density,and Interior Structure

The effects of pellet morphology, diameter, density, and interior structure on L-lactic acid fermentation by Rhizopus oryzae were characterized for different inoculum sizes and concentrations of peptone and CaCO₃. Inoculum size was the most important factor determining pellet formation and diameter. The diameter decreased with increasing inoculum size, and larger pellets were observed for lower inoculum sizes. Peptone concentration had the greatest effect on pellet density, which increased with increasing peptone concentration. L-lactic acid production depended heavily on pellet density but not on pellet diameter. Low-density pellets formed easily under conditions of low peptone concentration and often had a relatively hollow structure, with a thin condensed layer surrounding the pellet and an extraordinarily loose biomass or hollow center. As expected, this structure greatly decreased production. The production of L-lactic acid increased until the density reached a certain level (50–60 kg/m³), in which the compact part was distributed homogeneously in the thick outer layer of the pellet and loose in the central layer. Homogeneously structured, denser pellets had limited mass transfer, causing a lower overall turnover rate. However, the interior structure remained nearly constant throughout all fermentation phases for pellets with the same density. CaCO₃ concentration only had a slight influence on pellet diameter and density, probably because it increases spore germination and filamentous hypha extension. This work also provides a new analysis method to quantify the interior structure of pellets, thus giving insight into pellet structure and its relationship with productivity.     

珍稀植物日本荚蒾遗传多样性的ISSR分析

日本荚蒾是浙江省重点保护野生植物，种群数量极为稀少，仅零星分布于部分海岛。在野外调查的基础上，对8个居群共125份日本荚蒾样品进行了ISSR遗传多样性分析。从100条ISSR通用引物中筛选出7条引物用于ISSR-PCR，共扩增得到240个谱带，其中多态性谱带232个。在物种水平上，日本荚蒾的多态性位点百分比（PPB）达96.67%，Nei’s基因多样性指数（H）为0.227 3，Shannon’s信息指数（I）为0.358 1，具有较高的遗传多样性；在居群水平上，日本荚蒾的PPB为32.61%，H为0.073 1~0.136 3，均值为0.108 8；I为0.109 2~0.205 1，均值为0.164 2；居群间基因分化系数（Gst）为0.527 1，基因流（Nm）为0.448 7，遗传距离为0.098 2~0.254 0；聚类分析结果表明，同一地理来源的日本荚蒾大多聚为一类，呈一定的地域分布规律。日本荚蒾遗传多样性水平高，但主要存在于居群间，岛屿之间的地理隔离可能是遗传分化的主要原因。     

Engineering of Portable Smartphone Integrated with Liposome-Encapsulated Curcumin for Onsite Visual Ratiometric Fluorescence Imaging of Hypochlorite

Precisely onsite monitoring of hypochlorite (ClO⁻) is of great significance to guide its rational use, reducing/avoiding its potential threat toward food safety and human health. Considering ClO⁻ could quench fluorescence of curcumin (CCM) by oxidizing the o-methoxyphenol of CCM into benzoquinone, a portable ratiometric fluorescence sensor integrated with smartphone was designed for realizing the visual point-of-care testing (POCT) of ClO⁻. The amphiphilic phospholipid polymer was used as carrier to wrap curcumin, forming a novel liposome-encapsulated CCM, which provided a scaffold to bind with [Ru(bpy)₃]²⁺ through electrostatic interaction, thus assembling [Ru(bpy)₃]²⁺-functionalized liposome-encapsulated CCM ([Ru(bpy)₃]²⁺@CCM-NPs). Further integrated with smartphone, visual imaging of [Ru(bpy)₃]²⁺@CCM-NPs could be achieved and the accurate onsite detection of ClO⁻ could be realized with a detection limit of 66.31 nM and a linear range of 0.2210 to 80.0 μM. In addition, the sensor could monitor ClO⁻ in real samples with an onsite detection time of ∼154.0 s.     

Efficient synthesis of prasugrel, a novel P2Y12 receptor inhibitor

An efficient synthesis of prasugrel, a novel P2Y₁₂ receptor inhibitor, is described. The cyclopropyl-phenylethanone intermediate was prepared by cyanide substitution, bromination, N-substitution, and the Grignard reaction. After acid hydrolyzation of the methyl ether and subsequent acetylation, the title product was obtained with a total yield of 21% after 10 linear steps from simple and commercially available raw materials.     

磁性Ag@Fe3O4@C负载纳米金的制备及其SERS性能

利用一步溶剂热法制备了具有核壳结构的Ag@Fe₃O₄磁性纳米颗粒,然后以葡萄糖作为碳源对Ag@Fe₃O₄进行包覆,再利用酰胺化反应成功的将聚乙烯亚胺（PEI）修饰到Ag@Fe₃O₄@C表面,最后以N-Au共价键的方式将Au纳米粒子组装到Ag@Fe₃O₄@C表面。以4-巯基苯甲酸（4MBA）为拉曼活性探针分子来考察该复合纳米材料的表面增强拉曼（SERS）性能。通过控制Au纳米粒子的加入量,来调节Ag@Fe₃O₄@C-Au复合纳米材料的SERS活性。通过实验测试及利用时域有限差分法（FDTD）得出不同纳米金用量包覆的Ag@Fe₃O₄@C磁性纳米颗粒对4MBA的SERS效果依次为Ag@Fe₃O₄@C-Au-40 > Ag@Fe₃O₄@C-Au-10 > Ag@Fe₃O₄@C-Au-60 > Ag@Fe₃O₄@C,其中Ag@Fe₃O₄@C-Au-40的饱和磁化强度为411 A·g^-1,其对4MBA的检测限为1×10^-9 mol·L^-1。这种功能性复合材料既具有良好的SERS活性,又可通过外加磁场的方式实现对待测分子的分离、富集。     

An anomalous thermal expansion in the perovskite system,Gd1−xSrxMnO3 (0 ≤ x ≤ 0.3)

The thermal expansion behavior of sintered samples of Gd_1−xSr_xMnO₃ (X = 0.0–0.4) was studied. The sintered bodies in this system showed negative thermal expansion over a wide temperature range. The detailed crystal structure refinements with respect to temperature showed that the volume of the orthorhombic perovskite lattice monotonically increased with temperature, however, in addition to this, the release of distortion from the Jahn-Teller effect of Mn³⁺ ion occurred over a wide temperature range, which brought the negative expansion of the a-axis, although the b- and c-axes increased with temperature. The anomalous thermal expansion is explained by the sum of the effects of the shrinkage of the a-axis and absorption of the b- and c-axes' expansion by the pores in the sintered body.     

Preparation and characterisation of polyaniline based membranes for gas separation

Transport rates (permeability) and ideal separation factors for several gas pairs through dense polyaniline membranes are reported. The ideal separation factors for all gas pairs tested were found to be independent of the polyaniline membrane thickness whereas the permeability of the single gases showed significant variations. Both dedoped and redoped films (film thickness between 9 and 67 μm) were studied. The highest selectivities α_(A/B) found were 7.6 for the gas pair H₂/CO₂ in the case of the dedoped membrane and 10 for the gas pair H₂/CO₂, 6 for O₂/N₂ and 200 for H₂/N₂ in the case of the redoped membrane. Statistical analysis of a large number of membranes allowed the critical comparison with results obtained by other groups.Comparison with other membrane materials shows that an approximately sixfold enhancement of the respective separation factors is possible for gas pairs containing hydrogen. Similar separation factors are observed for the gas pairs CO₂/O₂, CO₂/N₂ and N₂/O₂.Membranes for which Knudsen diffusion was observed exhibited regularly distributed micropores (400 nm diameter).