HPLC法测定麻疯树不同部位两种二萜的含量

本文建立了两种麻疯树二萜麻疯树酚酮 B和Curcusone B的含量测定方法.采用Alltima C18色谱柱(4.6mm×250mm,5μm),流动相为甲醇-水(70:30),流速为1.0 mL·min-1,紫外检测波长为 254 nm.实验结果表明:麻疯树酚酮 B和Curcusone B的线性范围分别为2.26-1...     

火焰原子吸收光谱法测定血清中钙、铁、锌——消化方法的改进及其应用

为建立一种更为准确、快速、简便的营养流行病学调查的生化检验方法,应用改进的消化方法将血清充分消化,然后应用火焰原子吸收光谱仪测定血清中钙、铁和锌的含量。结果表明,本消化方法所得实验结果空白值低、精密度高、加标回收率在95％-105％之间、质控血清的测定含量与推荐值一致,3种元素的标准回归曲线相关系数r都在0．999以上,1200份健康人血清中钙、铁和锌的测定值与文献相同。该消化方法简单,准确,所需血清量少,适合用于大规模人群的营养流行病学检测。     

Morphological effect on electrochemical performance of nanostructural CrN

Size and morphology are critical factors in determining the electrochemical performance of the supercapacitor materials, due to the manifestation of the nanosize effect. Herein, different nanostructures of the CrN material are prepared by the combination of a thermal-nitridation process and a template technique. High-temperature nitridation could not only transform the hexagonal Cr₂O₃ into cubic CrN, but also keep the template morphology barely unchanged. The obtained CrN nanostructures, including (i) hierarchical microspheres assembled by nanoparticles, (ii) microlayers, and (iii) nanoparticles, are studied for the electrochemical supercapacitor. The CrN microspheres show the best specific capacitance (213.2 F/g), cyclic stability (capacitance retention rate of 96% after 5000 cycles in 1-mol/L KOH solution), high energy density (28.9 Wh/kg), and power density (443.4 W/kg), comparing with the other two nanostructures. Based on the impedance spectroscopy and nitrogen adsorption analysis, it is revealed that the enhancement arised mainly from a high-conductance and specific surface area of CrN microspheres. This work presents a general strategy of fabricating controllable CrN nanostructures to achieve the enhanced supercapacitor performance.     

解吸电晕束电离源质谱法快速检测食品包装材料中的双酚A

采用解吸电晕束电离源(DCBI)与质谱联用法测定食品包装材料中的双酚A。优化了萃取溶剂和离子源等参数。DCBI优化后,甲醇为萃取溶剂,检测模式为负离子模式,电离电压为!2 kV,离子传输管温度225℃,He气体流速1.0 L/min。当选用全扫描的模式时,单个样品测定时间小于30 s,对双酚A的检出限为0.1 mg/L,在1~100 mg/L浓度范围内线性良好,相关系数达到0.98,直接检测食品包装材料中的双酚A时,平均回收率为94%~125%,测定结果的相对标准偏差(RSD)小于17%。本方法分析速度快,灵敏度高,基体影响小,适用于大量样品快速检测。     

Third-Order Nonlinear Optical Properties of a Series of Polythiophenes

The third-order nonlinear optical properties of a series of polythiophenes are investigated with the Z-scan method under picosecond pulse laser irradiation at 532nm. The copolymers exhibit a good nonlinear response： large nonlinear refraction coefficients without nonlinear absorption. The signs of nonlinear refraction coefficients are positive, which are opposite to the negative signs of the polythiophene reported before. The mechanism accounting for the process of nonlinear refraction under pulse laser excitation is analyzed from the viewpoint of the electrondonor/acceptor units of polythiophenes. Moreover, changes of nonlinearity according to the lengths of main chains in polythiophene molecules are discussed.     

偶氮液晶聚合物薄膜的二维偏振全息记录

利用偏振全息记录的方法在一种含偶氮侧链的液晶聚合物薄膜中写入了二维偏振光栅.实验采用两束正交偏振的532 nm线偏光作为写入光,在样品同一点上分别记录了相互垂直的两个一维偏振光栅,继而对所构成的二维偏振光栅的特性进行了研究.实验结果表明：二维光栅的衍射效率比一维光栅低,其偏振特性是两个一维光栅元特性的叠加;二维光栅衍射效率对入射光偏振态的依赖性和光栅的偏振转换性质来源于材料中线双折射和圆双折射的共同作用. 关键词： 偏振全息 二维光栅 偶氮液晶聚合物     

Inverse Relaxation of Photoinduced Birefringence in a Liquid-Crystalline Azobenzene Side-Chain Polymer

Photoinduced birefringence in a liquid-crystalline azobenzene side-chain polymer is investigated. It is observed that the birefringence does not show any decay but increases after switching off the pump light at room temperature. The magnitude of the birefringence relaxation is found to depend on the exposure dose of the pump light. A discussion about the mechanism of the inverse relaxation of birefringence is presented.     

新型手性芳杂环分子钳人工受体的微波干法合成

在微波无溶剂条件下,以对苯二甲酰氯为隔离基,胆甾为手臂,固体K2CO3为载体,设计并合成了4个新型的手性芳杂环分子钳(3a～3d),其结构经1HNMR,IR,MS和元素分析表征。考察了微波辐射条件对反应的影响,结果表明,以固体K2CO3为载体,于450 W辐射4 min,收率最高(90%)。用UV-Vis初步研究了3a～3d对客体氨基酸甲酯的识别性能。结果表明,它们均对氨基酸甲酯有良好的对映选择性识别作用。     

热电池正极材料的研究进展

热电池是一种热激活贮备式电池,由于其优良的贮存稳定性、放电可靠性等特点,广泛应用于多种军用武器的内部电源。为了满足当前不同军用武器装备的需求,热电池的发展趋于在提高电化学性能的同时实现小型化、微型化。热电池电化学性能的提高主要取决于正极材料的发展,目前对现有正极材料的优化改性和新型正极材料的开发是提高热电池性能的主要方法。本文从合成和改性方法的角度综述了近年来硫化物、氯化物、氟化物热电池正极材料的研究进展,并对其材料特性和放电性能进行了综合评估。最后,基于热电池特殊的应用场景,从热稳定性、放电电压、电导率等方面对热电池正极材料未来的发展方向进行了总结与展望。     

Temperature Dependence of Photoinduced Birefringence in an Azobenzene Polymer

The photoinduced birefringence in an azobenzene polymer is investigated at different temperatures between -20℃ to 50℃. It is found that there is a peak value of photoinduced birefringence in the temperature dependence of the photoinduced birefringence under a certain pumping intensity. With the pump light in 90mW/cm^2, the peak value of the photoinduced birefringence appeared at about 0℃ C. The effect of temperature on the photoinduced birefringence is discussed using the competition mechanism between the photoinduced reorientation and the thermal random motion.