内-α-取代-α-甲基双环[2,2,1]庚烷-2-基甲醇的合成及其结构与香气的关系

合成了18种内-α-取代-α-甲基双环[2,2,1]庚烷-2-基甲醇(Ⅰ)。测定了所有化合物的折光率(或熔点)、质谱、红外光谱、~1H核磁共振谱、气相色谱的保留时间和薄层色谱的比移值。评定了它们的香气,并与相应的内-α-取代-α-甲基双环[2,2,1]-5-庚烯-2-基甲醇(Ⅱ)系列化合物的香气进行了比较,初步探讨了结构与香气的关系。     

Photocatalytic degradation of methylene blue on Fe3+-doped TiO2 nanoparticles under visible light irradiation

Fe³⁺-doped TiO₂ composite nanoparticles with different doping amounts were successfully synthesized using sol-gel method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and ultravioletvisible spectroscopy (UV-Vis) diffuse reflectance spectra (DRS). The photocatalytic degradation of methylene blue was used as a model reaction to evaluate the photocatalytic activity of Fe³⁺/TiO₂ nanoparticles under visible light irradiation. The influence of doping amount of Fe³⁺ (ω: 0.00%–3.00%) on photocatalytic activities of TiO₂ was investigated. Results show that the size of Fe³⁺/TiO₂ particles decreases with the increase of the amount of Fe³⁺ and their absorption spectra are broaden and absorption intensities are also increased. Doping Fe³⁺ can control the conversion of TiO₂ from anatase to rutile. The doping amount of Fe³⁺ remarkably affects the activity of the catalyst, and the optimum efficiency occurs at about the doping amount of 0.3%. The appropriate doping of Fe³⁺ can markedly increase the catalytic activity of TiO₂ under visible light irradiation. __________ Translated from Journal of Northwest Normal University (Natural Science), 2006, 42(6): 55–56 [译自: 西北师范大学学报(自然科学版)]     

Effects of C3-aromatic heterocycles on 1,3,5-triaryl-2-pyrazoline sulfonium salt photoacid generators as light-emitting diode-sensitive cationic photoinitiators

Four 1,5-diphenyl-3-aromatic heterocyclyl-2-pyrazoline-based sulfonium salt photoacid generators (PAGs) with different aromatic heterocycles substituted on C3 atom and dimethyl sulfonium group on C5 atom were synthesized. These PAGs were highly photosensitive in the 365–425 nm light-emitting diode region, and the intramolecular charge transfer from the pyrazoline ring to sulfonium salts induced efficient photolysis and high Φ_H⁺. The heterocycles as well as their substituted positions significantly influenced the energy of the S₂ orbital, which was determined by the electrochemical and absorption properties of the PAGs. The raising of the S₂ orbital energy enlarged the energy gap of S₀–S₂ and S₁–S₂, resulting in blue shift of the absorption spectra and increase in the quantum yield of photoacid generation (Φ_H⁺), respectively. When the energy of excited electrons was higher than that of the S₂ orbital, the transition from S₀ to S₂ (π–π*) occurred before the C-S cleavage on S₁ and the PAGs showed high Φ_H⁺ values (0.52–0.72). The transition from S₀ to S₁ (π–σ*) occurred when the energy of electrons is lower than that of the S₂ orbital, and the PAGs showed low Φ_H⁺ value. The photopolymerization kinetics demonstrated that these PAGs were highly efficient cationic photoinitiators.     

Annealing effect on the ultrafast dynamics of Ag nanoparticles embedded in soda-lime silicate glasses

Ag nanoparticles embedded in soda-lime silicate glasses were fabricated by the ion-exchange technique. Effects of thermal treatment on the optical nonlinearity and ultrafast dynamics of Ag nanoparticles were investigated by applying time-resolved optical Kerr effect and pump-probe techniques. The results indicate that thermal treatment is an efficient method to improve the nonlinear optical performance of this kind of material.     

弯曲狭窄管内血液流的分析

与血管狭窄有关的异常血液动力学特征在血管疾病的发生和发展过程中起着重要的作用,由于血管狭窄和弯曲的综合影响,将会出现一系列有趣的流体力学现象,本文研究具有对称狭窄的弯曲小动脉内定常血液流动,在一定的假设条件下,直接从支配血液流动的Navier-Stokes方程求出问题的摄动解,由此求得弯曲狭窄管內血液流动的轴向速度、二次流速度及压力梯度等分析表达式,并进一步求得轴向和周向血管壁切应力。本文的结果是先前有关狭窄直管和弯曲均匀管流动研究的拓广。     

Template‐Free Fabrication of Hollow NiO–Carbon Hybrid Nanoparticle Aggregates with Improved Lithium Storage

Hollow NiO–carbon hybrid nanoparticle aggregates are fabricated through an environmental template‐free solvothermal alcoholysis route. Controlled hollow structure is achieved by adjusting the ratio of ethylene glycol to water and reaction time of solvothermal alcoholysis. Amorphous carbon can be loaded on the NiO nanoparticles uniformly in the solvothermal alcoholysis process, and the subsequent calcination results in the formation of hollow NiO–C hybrid nanoparticle aggregates. As anode materials for lithium‐ion batteries, it exhibits a stable reversible capacity of 622 mAh g^?1, and capacity retention keeps over 90.7% after 100 cycles at constant current density of 200 mA g^?1. The NiO–C electrode also exhibits good rate capabilities. The unique hollow structures can shorten the length of Li‐ion diffusion and offer a sufficient void space, which sufficiently alleviates the mechanical stress caused by volume change. The hybrid carbon in the particles renders the electrode having a good electronic conductivity. Here, the hollow NiO‐C hybrid electrode exhibits excellent electrochemical performance.     

2,4-二硝基苯丙氨酸钠盐·2,4-二硝基苯丙氨酸的合成、分子结构和二次谐波效应

合成了一种新的有非线性光学性能的标题化合物晶体NaAP·HAP,晶体属正交晶系,空间群为P2_12_12_1,a=25.773(6),b=12.377(3),c=7.2037(6)(?),z=4,D_c=1.54g·cm~(-3)。晶体结构由HAP分子(2,4-二硝基苯丙氨酸)、AP~-离子和Na~+离子组成。Na~+离子由周围的六个氧原子形成扭曲的八面体配位。这些NaO_6八面体通过共点形成无限链状结构。可用晶体结构的空间因素来解释实验测定的MAP和NaAP·HAP的二次谐波相对强度的顺序。     

掺杂CdS超微粒的ZrO2薄膜的光学性质

研究了用溶胶凝胶方法制备的CdS超微粒 ZrO2 薄膜的发光特性 ,测量了不同退火温度处理的样品的荧光光谱、荧光激发光谱和荧光衰减曲线的变化 ,通过荧光衰减曲线研究了 14 0 ps左右的CdS的带间跃迁发射和较慢的表面态发射。还测量了这种掺有CdS超微粒的ZrO2 薄膜的飞秒光克尔效应 ,得到三阶非线性光学极化率为4 4× 10 - 1 1 esu和大约 10 0fs的响应时间。结果表明 ,这类材料具有较大的光学非线性和快速的响应时间 ,在高速光开关等方面有潜在的应用前景     

Efficient Electrocatalytic Reduction of CO2 by Nitrogen-Doped Nanoporous Carbon/Carbon Nanotube Membranes: A Step Towards the Electrochemical CO2 Refinery

Herein we introduce a straightforward, low cost, scalable, and technologically relevant method to manufacture an all-carbon, electroactive, nitrogen-doped nanoporous-carbon/carbon-nanotube composite membrane, dubbed “HNCM/CNT”. The membrane is demonstrated to function as a binder-free, high-performance gas diffusion electrode for the electrocatalytic reduction of CO₂ to formate. The Faradaic efficiency (FE) for the production of formate is 81 %. Furthermore, the robust structural and electrochemical properties of the membrane endow it with excellent long-term stability.     

A study on melt grafting of maleic anhydride onto low‐density polyethylene and its blend with polyamide 6

Graft copolymerization of low‐density polyethylene (LDPE) with a maleic anhydride (MAH) was performed using intermeshing corotating twin‐screw extruder in the presence of benzoyl peroxide (BPO). The LDPE/polyamide 6 (PA6) and LDPE‐g‐MAH/PA6 blends were prepared in a corotating twin‐screw extruder. The melt viscosity of the grafted LDPE was measured by a capillary rheometer. The grafted copolymer was characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microcopy (SEM). The influence of the variation in temperature, BPO and MAH concentration, and temperature on the grafting degree and on the melt viscosity was studied. The grafting degree increased appreciably up to about 0.45 phr and then decreased continuously with an increasing BPO concentration. According to the FTIR analysis, it was found that the amount of grafted MAH on the LDPE chains was ～5.1%. Thermal analysis showed that melting temperature of the graft copolymers decreases with increasing grafting degree. In addition to this, loss modulus (E″) of the copolymers first increased little with increasing grafting and then obviously decreased with increasing grafting degree. Furthermore, the results revealed that the tensile strength of the blends increased linearly with increasing PA6 content. The results of SEM and mechanical test showed that the blends have good interfacial adhesion and good stability of the phase structure, which is reflected in the mechanical properties. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 267–275, 2010