六水合三氯化铁催化3-甲基环己酮与丙酮酸乙酯交叉羟醛缩合制备薄荷内酯

用FeCl3·6H2O催化3-甲基环己酮与丙酮酸乙酯交叉羟醛缩合,制得2-(2-氧代-4-甲基环己叉基)丙酸乙酯和7a-羟基薄荷内酯,皂化后用硼氢化钠还原、酸化制得(±)-薄荷内酯,产率为51%。考察了3-甲基环己酮的烯醇式异构化的位置选择性和粗产物中(±)-薄荷内酯与(±)-异薄荷内酯异构体的比例。     

镧掺杂纳米TiO2覆膜陶瓷的光催化自洁净和抗菌性能

采用溶胶-凝胶法制备了掺镧纳米TiO2薄膜,并用浸渍提拉法覆膜在陶瓷表面.最佳工艺条件为:覆膜层数为3,焙烧温度为500℃,掺镧量为La3 /TiO2=0.003(摩尔比).用XRD、SEM等方法研究了薄膜的结构与形貌.陶瓷覆膜镧掺杂纳米TiO,具有良好的亲水性能,抗菌率高达99%.     

Optical study of charge dynamics in CaCo_2As_2

We present an infrared spectroscopy study of charge dynamics in CaCo_2As_2 single crystal. In this material, the optical conductivity can be described by two Drude components with different scattering rates(1/τ): a broad incoherent background and a narrow Drude component. By monitoring the temperature dependence, we find that only the narrow Drude component is temperature-dependent and determines the transport properties. Especially a Fermi liquid behavior of carriers is revealed by the T~2 behavior in the dc resistivity ρ_n and scattering rate 1/τ_n, indicating a coherent nature of quasiparticles in the narrow Drude subsystem.     

几种保润剂对卷烟烟气化学成分的影响

考察了不同类别的保润剂(丙二醇、甘油、27664号保润剂、木糖醇和山梨醇)对卷烟烟气化学成分的影响,包括对烟气总粒相物、烟碱、水分、焦油含量及卷烟烟气中致香成分组成和有害物质含量的变化。结果表明:①加入不同种类的保润剂后对卷烟烟气的化学成分有明显的影响,而且其影响随着添加量的变化而变化。②随着各种保润剂的加入,卷烟烟气中致香成分总量均比空白卷烟烟气显著增大,同时烟气中苯类和胺类有害物质含量也增大。     

Magnetoresistivity and filamentary superconductivity in nickel-doped BaFe_2As_2

We present magnetotransport studies on a series of BaFe_(2-x)Ni_xAs_2(0.03 ≤ x ≤ 0.10) single crystals. In the underdoped(x = 0.03) non-superconducting sample, the temperature-dependent resistivity exhibits a peak at 22 K, which is associated with the onset of filamentary superconductivity(FLSC). FLSC is suppressed by an external magnetic field in a manner similar to the suppression of bulk superconductivity in an optimally-doped(x = 0.10) compound, suggesting the same possible origin as the bulk superconductivity. Our magnetoresistivity measurements reveal that FLSC persists up to the optimal doping and disappears in the overdoped regime where the long-range antiferromagnetic order is completely suppressed, pointing to a close relation between FLSC and the magnetic order.