纳米氧化铋的研究进展

综述了纳米氧化铋的发展研究现状,总结了近年来发展起来的几种制备纳米氧化铋的新方法的优缺点,以及纳米氧化铋作为电子功能材料、燃速催化剂、光催化降解材料、光学材料、医用复合材料和防辐射材料等方面的主要应用。     

Study of the aggregation of 1-alkanoylperylenes in 1,4-dioxane-H_2O binary solvents-Derivation of a new empirical equation relating CAgC to both chain-length and solvent aggregating power

Aggregation behaviors of 1-alkanoylperylenes (Pe-n, n = 4, 8,12) driven by hydrophobic-lipophilic interaction (HLI) have been investigated in dioxane (DX )-H2O binary aquiorgano solvents by means of fluorescence spectroscopy. A novel empirical equation, which rationalizes CAgC (critical aggregate concentration) dependence of the aggregates both on the chain-length of the substituent alkyl group and on the solvent aggregating power (SAgP) for Pe-n, has been derived.     

两个非全氢键介质的芳酰肼七聚体对n-辛基-alpha-L-吡喃糖苷的络合作用

本文报道了两个芳酰肼七聚体的合成,它们分别由两个氢键介质的折叠片段组成.与其全氢键介质的类似物相比,这两个七聚体的骨架因中间的芳环减少了一个和两个分子内氢键而流动性增加.^1H NMR,园二色谱及荧光研究表明,这两个寡聚体能够在氯仿中中等程度地络合n-辛基-α-L-吡喃糖苷.     

非球面手机屏幕放大镜的设计

为方便老年人、视力障碍者等特殊人群看清手机上的文字及图像,采用ZEMAX光学设计软件,从高折射率材料,镜片面型和类型的选择上,以及从使用双胶合镜或非球面等方面设计了几款手机屏幕放大镜.通过分析手机屏幕放大镜特点,发现用非球面镜片不仅可以改善屏幕周边的像质并可减小镜片厚度.最后,还设计了几种放大镜与手机的契合方式,以克服现有手机放大镜片的不足.     

用飞秒激光在α-BBO晶体中诱导析出β-BBO相

通常超快强激光主要用于研究发生在材料内部,时间尺度在皮秒(10^-2s)到飞秒(10^-15s)范围内的动力学现象。然而,其极短的脉冲宽度,使得激光束经聚焦后在焦斑处的功率强度可达10^14W／cm^2。所以,当这种激光束被聚焦在透明材料的内部时,巨大的能量可在极短的时间内积聚在非常小的区域内,并使该区域内的温度和内压力急剧上升。     

基于介观力学信息的颗粒材料损伤-愈合与塑性宏观表征

本文在二阶计算均匀化框架下提出了颗粒材料损伤-愈合与塑性的多尺度表征方法.颗粒材料结构在宏观尺度模型化为梯度Cosserat连续体,在其有限元网格的每个积分点处定义具有离散颗粒介观结构的表征元.建立了表征元离散颗粒系统的非线性增量本构关系.表征元周边介质作用于表征元边界颗粒的增量力与增量力偶矩以表征元边界颗粒的增量线位移与增量转动角位移、当前变形状态下表征元离散介观结构弹性刚度、以及凝聚到表征元边界颗粒的增量耗散摩擦力表示.基于平均场理论与Hill定理,导出了基于介观力学信息的梯度Cosserat连续体增量非线性本构关系.在等温热动力学框架下定义了表征颗粒材料各向异性损伤-愈合和塑性的损伤、愈合张量因子与综合损伤、愈合效应的净损伤张量因子和塑性应变.此外,定义了损伤和塑性耗散能密度与愈合能密度,以定量比较材料损伤、愈合、塑性对材料失效的效应.应变局部化数值例题结果显示了所建议的颗粒材料损伤-愈合-塑性表征方法的有效性.     

酰基过氧化物的化学 Ⅴ.过氧化五氟苯甲酰在不同溶剂中的热分解

过氧化五氟苯甲酰(FBPO)稀溶液(<0.02mol·dm~(-3))的热解动力学和产物分析表明:在碳卤和碳氢溶剂中的分解为单分子均裂过程.前者产物极为复杂,后者以羧基攫氢产物为主.在强极性溶剂中FBPO的分解被大大加速,生成高产率或定量的五氟苯甲酸,表明溶剂可能通过单电子转移或双分子亲核取代及诱导分解等途径参与FBP0的热解.     

不同取代三氟苯乙烯交叉环加成反应过渡态的额外极性相互作用 1.对三氟甲基三氟苯乙烯和对甲氧基三氟苯乙烯环加成反应的动力学研究

利用 KINETICS-1计算机程序,测定了在120—160℃四个温度下对甲氧基三氟苯乙烯与对三氟甲基三氟苯乙烯的交叉和均环加成反应的速率常数.我们的数据,特别是与交叉环加成反应的趋向有关的,并由方程(10)所定义的φ函数值(1.4—1.9)表明,在给电子基取代的和吸电子基取代的三氟苯乙烯之间的交叉环加成反应的过渡态中,非常可能存在着一个额外的极性相互作用.     

MICROENVIRONMENTAL EFFECTS OF THE HELICAL CONFORMATIONS OF AMYLOSE AND ITS DERIVATIVES——THE FORMATION OF INCLUSION COMPLEXES WITH A SUBSTRATE BY AMYLOSE IN THE DMSO-H_2O MIXED-SOLVENT SYSTEM

The conformational behavior of amylose and the formation of helical inclusion complexesof amylose with a substrate, N-ethyl-4-hexadecyloxycarbonyl pyridinium iodide (1) -- asolvent-polarity probe, have been investigated in the DMSO--H_2O mixed-solvent system bymeans of surface tension, viscosity, UV, electrical conductance and ORD measurements. Thedecrease of the volume-fraction of DMSO, Φ_(DMSO) of the mixed-solvent system inducesconformational changes of the amylose from tight helices to loose and extended helicesinterrupted by short disordered regions. Such a transition is accompanied by abrupt changesof the viscosity and ORD curves. The mechanism of interaction between amylose and the substrate 1 also depends on thesolvent composition. When Φ_(DMSO) is larger than 0.70, the interaction of amylose with 1is apparently similar to those cases in which superhelices are formed between a macromo-lecule and some azo dyes; the latter are known to be bound exteriorly around the macro-molecular helices by oriented association. However, when Φ_(DMSO) begins to drop below0.70, the substrate molecules start to be bound in the helical cavities of the host and thussupramolecular inclusion complexes are formed. At Φ_(DMSO)<0.70, ORD shows a new nega-tive Cotton peak at a wavelength which coincides with the λ_(max) of 1 (276 nm). This implicatesinduced asymmetry for the achiral substrate 1 in a chiral microenvironment. Intrinsicdissociation constants (K_(d~*)) for the inclusion complexes can be obtained from the surface ten-sion- substrate concentration (σ-[1]) curves and the largest number of binding sites isfound to be below 30. The K_(d~*) values decrease with decreasing Φ_(DMSO), apparently inagreement with the results from conductance measurements. Presumably, the driving forcefor the transfer of the substrate molecules from the solvent-mixture bulk phase to the non-polar cavities of the host molecules comes from hydrophobic-lipophilic interactions.     

辅酶胶团的研究——具有长疏水链的维生素B_6类似物的合成及性质

依赖于PDP(吡哆醛磷酸酯,维生素B_6)的酶系是参与生物体内氨基酸代谢和光合作用的重要组份。我们设计了装配具有不同位置的疏水链的维生素B_6类似物的合成表面活性剂胶团作为模型,以通过模拟依赖于PDP的酶系的物理化学行为来确定微环境的疏水性在酶蛋白功能中的作用。以吡哆醇为原料合成了具有疏水链的维生素B_6类似物2,3和4,三者皆为新的化合物。