Ag@YF3:Eu3+核壳结构纳米材料的制备与性能研究

采用乙二醇法制备了单质Ag纳米粒子,并通过直接沉淀法合成了均匀球形的Ag@YF3∶Eu3+核壳结构复合纳米发光粒子,对产物的结构和性能进行了表征。XRD分析表明:Ag表面包覆上了结晶良好的正交晶系的YF3∶Eu3+。TEM照片表明:所得的纳米复合粒子具有明显的核壳结构和均匀的球形,中间Ag粒子的尺寸在80~100 nm之间,Ag@YF3∶Eu3+的粒径尺寸约为150~180 nm,表面粗糙且包覆完全。电子衍射表明复合样品为多晶。荧光光谱表明:该纳米复合粒子具有良好的发光性,以593 nm附近的5D0→7F1磁偶极跃迁为最强发射峰,但是比纯的YF3∶Eu3+的发光强度要弱,其荧光寿命有所增强,这表明Ag纳米粒子对外层的YF3∶Eu3+的发光有猝灭作用。     

可溶液加工的有机-无机杂化钙钛矿:超越光伏应用的“梦幻”材料

有机-无机杂化钙钛矿材料是可通过溶液工艺低温制备得到的直接带隙半导体晶体薄膜.在众多可溶液加工的半导体材料中,有机-无机杂化钙钛矿薄膜是为数不多的低缺陷密度、双极子传输性能优异的晶体薄膜,同时兼具宽光谱吸收和长载流子扩散距离等特性,是平面异质结太阳能电池的理想选择.另外,作为低缺陷密度的直接带隙半导体晶体材料,杂化钙钛矿薄膜具有优异的发光特性.其发光波长可通过能带工程(在分子水平上改变其组分)进行调节,因此有望在发光二极管和激光等光电器件中得到新应用.总结了钙钛矿材料的优异特性和目前应用研究的进展,并对其未来发展做了展望.     

Photoelastic stress analysis of an elliptical hole in a thick plate subjected to uniform in-plane compressive Loading

A three-dimensional photoelastic analysis was conducted to determine the stress distribution and concentration around the periphery of a centrally located elliptical hole in a plate of finite thickness. The edge of the plate was subjected to a uniformly distributed compressive uniaxial in-plane load. The principle of superposition was employed to study the effect of uniform biaxial loading.Elliptical holes with five different major/minor axis ratios () ranging from 1.0 to 2.64 were investigated. Among the results of this study, it was established that the variation of the principal stresses at the edge of the hole is not linear across the plate thickness. It was also found that in loading the plate in a direction parallel to the major axis of the ellipse, the value of the maximum tangential principal stress () occurs in a plane other than the middle plane of the plate. However, in loading the plate in a direction either parallel or perpendicular to the major axis, the maximum transverse stress ( _z ) occurs at the middle plane. In addition, the maximum value of ( _z ) was about 20 percent of the maximum value of the tangential stress for all models tested. Furthermore, the effect of the bixial loading has reduced the value of the maximum tangential stress at the periphery of the hole as compared with uniaxial loading.As a three-dimensional theoretical solution does not exist for this problem, the present findings were correlated with the well established two-dimensional solutions.     

Copper(I)‐Catalyzed Intramolecular N‐N Coupling of Cyclopropyl O‐Acyl Ketoximes: Synthesis of Spiro‐fused Pyrazolin‐5‐ones

A convenient copper‐catalyzed approach has been developed for the synthesis of substituted spiro‐fused pyrazolin‐5‐ones from readily available cyclopropyl O‐acyl ketoximes via an intramolecular N? N bond formation reaction. These catalytic reactions proceed in excellent yields with a broad scope.     

ChemInform Abstract: Pressure‐Induced Structural and Electronic Transition in Sr2ZnWO6 Double Perovskite.

Polycrystalline Sr₂ZnWO₆ is prepared by staged calcination of stoichiometric amounts of SrCO₃, ZnO, and WO₃ in air (Al₂O₃ crucible, 1.     

双水杨醛邻苯二胺柱前衍生-高效液相色谱法测定茶叶中的Pb~(2+)

建立了利用双水杨醛邻苯二胺希夫碱(SALOPHEN)作为衍生剂结合高效液相色谱(HPLC)测定茶叶中Pb~(2+)含量的方法。Hypersil ODS2 C18反相色谱柱(250 mm×4.6 mm,5μm)为固定相,甲醇-水(80∶20,v/v)为流动相,检测波长为226 nm,反应体系pH为10.0。结果表明,样品中Pb~(2+)的线性范围为0.1~30 mg/L,线性相关系数为0.998 8,检出限为0.01 mg/L,加标回收率为91.87%~96.96%。该方法具有较高的灵敏度和稳定性,适用于茶叶中Pb~(2+)的检测。     

一种巯基棉的制备方法及应用

研究了一种新的巯基棉准备方法,该方法利用三氟化硼乙醚作为催化剂,能够快速、便宜、简单地制备巯基棉,并且在浓缩烷基汞实验中取得良好的回收率。该方法在一定量(约100μL)的催化剂下反应效果良好,烷基汞回收率达到70%以上,在0.005~0.2 mg/L范围内,线性关系良好,标准偏差为1.5%~6.7%。该方法具有良好的应用前景。     

Ruthenium‐Catalyzed Monoalkenylation of Aromatic Ketones by Cleavage of Carbon–Heteroatom Bonds with Unconventional Chemoselectivity

Ruthenium‐catalyzed selective monoalkenylation of ortho C? O or C? N bonds of aromatic ketones was achieved. The reaction allowed the direct comparison of the relative reactivities of the cleavage of different carbon‐heteroatom bonds, thus suggesting an unconventional chemoselectivity, where smaller, more‐electron‐donating groups are more easily cleaved. Selective monofunctionalization of C? O bonds in the presence of ortho C? H bonds was also achieved.     

基于改进人工鱼群算法的LED混光方法

为寻求高LED颗粒利用率和高光效,引入了新LED组合进行混光,提出利用改进人工鱼群算法优化LED光通量配比,并设计了一款可调光调色筒灯来验证算法的可行性。引入相对基强化学习算法优化人工鱼种群;引入柯西分布和正态分布函数作为自适应算子,优化视域和步长。用积分球测试经优化后的灯具,数据表明灯具具有很高的颗粒利用率和光效。结果表明本文提出方法切实可行,具有很高的实用价值。     

多次循环离子交换色谱纯化Cry1Ab蛋白及其肽质量谱图的分析

采用Q-Sepharose FF离子交换柱对初步纯化的Cry1Ab杀虫蛋白样品进行了多次循环精细纯化，洗脱模式为离子强度台阶梯度，流动相为Tris-HCl缓冲液加NaCl，盐浓度从0．1mol·L^-1变化到1．0mol·L^-1．结果表明，Cry1Ab蛋白在NaCl浓度为0．4mol·L^-1时从柱上被洗脱，并与杂蛋白很好地分离．色谱分离机制符合顶替色谱机制．经3次循环分离后可获得高纯度的Cry1Ab蛋白．用SDS-PAGE分析了蛋白的纯度及表观分子量，电泳胶上分离的蛋白进行原住酶切后，用基质辅助激光解析-飞行时间质谱对纯化蛋白进行肽质量谱的分析，Mascot数据库搜索结果确证了该纯化蛋白酶解肽段80％符合已知的Cry1Ab蛋白特征肽段．