Visible-light-induced,autopromoted nickel-catalyzed three-component arylsulfonation of 1,3-enynes and mechanistic insights

Science China Chemistry - A light-induced, nickel-catalyzed three-component arylsulfonation of 1,3-enynes in the absence of photocatalyst is reported. This methodology exhibited mild conditions,...     

Characterization and bioactive potentials of secondary metabolites from Fusarium chlamydosporum

Abstract

A search for bioactive secondary metabolites from the endophytic fungus Fusarium chlamydosporum, isolated from the root of Suaeda glauca, led to the isolation of three indole derivatives (1–3), three cyclohexadepsipeptides (4–6), and four pyrones (7–10). The structures of new (1) and known compounds (2–10) were elucidated on the basis of extensive spectroscopic analysis. All these compounds were evaluated for phytotoxic, antimicrobial activities, and brine shrimp lethality. Compound 1 showed significant phytotoxic activity against the radicle growth of Echinochloa crusgalli, even better than the positive control of 2,4-D. Cyclohexadepsipeptides (4–6) and pyrones (7–10) exhibited brine shrimp lethality, especially 4 and 7 with the LD₅₀ values of 2.78 and 7.40?μg mL^?1, respectively, better than the positive control.     

AOT/水/甲苯微乳体系的第二维里系数和液滴间的相互作用

在一系列温度下通过对水与丁二酸双(2-乙基己基)酯磺酸钠(AOT)摩尔比为12、不同浓度的AOT/水/甲苯微乳液进行静态光散射测量, 获得液滴的相对分子质量、AOT的聚集数、液滴半径和不同温度下的第二维里系数. 利用第二维里系数与温度的关系获得液滴的相互作用焓和熵, 分别为-4.03×10⁴ J·mol^-1和-139.8 J·mol^-1·K^-1, 说明AOT/水/甲苯微乳液滴间表面活性剂疏水链相互交叉渗透的能量变化为负值, 交叉渗透为焓驱动.     

磁性可见光催化剂BiVO4/Fe3O4的制备及催化活性

采用超声法将磁基体Fe3O4和BiVO4复合,制备了易于固液分离的磁性可见光催化剂BiVO4/Fe3O4。采用X射线衍射(XRD)、傅立叶转换红外光谱(FTIR)、紫外-可见漫反射光谱(DRS)、透射电子显微镜(TEM)和磁学性质测量系统(MPMS)对产物进行了表征,并以亚甲基蓝为目标降解物,考察了BiVO4/Fe3O4的可见光催化活性。当BiVO4与Fe3O4质量比为5:1时,BiVO4/Fe3O4的催化活性最高,反应经过5 h,对亚甲基蓝的降解率达到92.0%,而单独使用BiVO4为催化剂,降解率仅为72.5%。这表明Fe3O4不仅起到磁基体的作用,还起到助催化剂的作用。BiVO4/Fe3O4在外加磁场的作用下很容易被分离,撤消外加磁场后,通过搅拌又可重新分散。BiVO4/Fe3O4 3次回收后的降解率仍高于80%。     

Effect of annealing temperature for Si0.8Ge0.2 epitaxial thin films

This study investigates the effect of annealing temperature on the Si_0.8Ge_0.2 epitaxial layers. The Si_0.8Ge_0.2 epitaxial layers were deposited by using ultrahigh vacuum chemical vapor deposition (UHVCVD) with different annealing temperatures (400-1000 °C). Various measurement technologies, including high-resolution X-ray diffraction (HRXRD), atomic force microscopy (AFM) and interfacial adhesion tester, were used to characterize the materials properties of the SiGe epilayers. The experimental results showed that the SiGe epilayers gradually reduced lattice-mismatch to the underlying substrate as annealing temperature increased (from 400 to 800 °C), which resulted from a high temperature enhancing interdiffusion between the epilayers and the underlying substrate. In addition, the average grain size of the SiGe films increased from 53.3 to 58 nm with increasing annealing temperature. The surface roughness in thin film annealed at 800 °C was 0.46 nm. Moreover, the interfacial adhesion strength increased from 476 ± 9 to 578 ± 12 kg/cm² with increasing the annealing temperature.     

超高压处理对荔枝果肉中两种酶和可溶性蛋白的影响

 为了研究超高压处理对荔枝果肉中过氧化物酶（POD）、果胶甲基酯酶（PME）及可溶性蛋白含量的影响,将荔枝（“淮枝”品种）果肉在100~400 MPa压力、10 ℃温度条件下处理30 min,采用分光光度法测定果肉中POD、PME的活性,用天然凝胶电泳法以及活性染色法测定POD、PME同工酶的变化,用SDS凝胶电泳法测定果肉中可溶性蛋白含量。结果表明：100~200 MPa超高压处理使荔枝果肉中POD活性上升且出现新的同工酶,300~400 MPa超高压处理则使其活性降低且新出现的同工酶消失;100 MPa压力处理使荔枝果肉中PME活性上升且出现新的同工酶,200~400 MPa超高压处理则使其活性降低且新出现的同工酶消失;100 MPa超高压处理使荔枝果肉中可溶性蛋白含量有所增加,而在200~400 MPa压力处理下其含量持续下降。     

二乙氧基硫代磷酸酯类有机磷农药单链抗体的制备及广谱特异性

从分泌抗二乙氧基硫代磷酸酯类有机磷农药(DPPs)单克隆抗体(MAb)的杂交瘤细胞系(12C2)中提取了总RNA, 经RT-PCR反转录成cDNA, 设计带linker引物, 采用重叠延伸PCR制备单链抗体(scFv)基因, 将其克隆到噬菌体载体p3MH中, 构建成噬菌体单链抗体表达载体, 转化大肠杆菌表达出噬菌体表面展示scFv, 对经过Phage-ELISA鉴定的阳性克隆进行噬菌体外壳蛋白基因geneⅢ的去除, 用IPTG诱导其可溶性表达, 对表达产物进行SDS-PAGE, Western-Blot及ELISA鉴定, 并与亲本MAb进行性能对比. 结果表明, 可溶性表达的scFv分子量为27000; scFv与DPPs的交叉反应率比其亲本MAb提高了1.3~3.5倍, 表明其广谱特异性有所提高. 由于scFv与MAb相比具有诸多优点, 因此本研究为有机磷农药多残留检测方法的建立提供了一种更广谱、 更灵敏的新型识别分子.     

沉淀法合成t-LaVO4∶Eu3+及其光致发光性质研究

用沉淀法在不同pH值下选择性合成了m-和t-LaVO4:Eu3+,合成过程未使用添加剂.用XRD、SEM、PL对样品进行了表征,并与水热法所制备样品的性质进行了比较.结果表明,样品在280 nm紫外光激发下能发射600～620 nm窄带红光,t-LaVO4:Eu3+发光性能远比m-LaVO4:Eu3+优越;pH值是选择性合成t-LaVO4:Eu3+的关键,pH值在6～9范围内,沉淀法与水热法都可得到t-LaVO4:Eu3+,其中pH值为7时样品发光强度最高.样品形貌对光致发光性质有重要影响,沉淀法所得到的t-LaVO4:Eu3+具有规则的形貌,尺寸为亚微米级.延长陈化时间可增强样品发光强度,常温下陈化12 h所得样品的发光强度与180℃水热2 h样品相近.Eu3+掺杂量也是影响样品发光性质重要因素,其最佳掺杂浓度为物质的量分数5%.t-LaVO4:Eu3+在600℃以下结构稳定,煅烧后样品发光强度不会下降.