Nickel-catalyzed cross-electrophile allylation of vinyl bromides and the modification of anti-tumour natural medicine β-elemene

Herein, we present a facile and efficient allylation method via Ni-catalyzed cross-electrophile coupling of readily available allylic acetates with a variety of substituted alkenyl bromides using zinc as the terminal reductant. This Ni-catalyzed modular approach displays excellent functional group tolerance and a broad substrate scope, which the creation of a series of 1,4-dienes including several structurally complex natural products and pharmaceutical motifs. Moreover, the coupling strategy has the potential to realize enantiomeric control. The practicality of this transformation is demonstrated through the potent modification of the naturally antitumor active molecule β-elemene.

Herein, we present a facile and efficient allylation method via Ni-catalyzed cross-electrophile coupling of readily available allylic acetates with a variety of substituted alkenyl bromides using zinc as the terminal reductant.     

Fe掺杂α-Bi2O3光电性质的第一性原理研究

采用第一性原理杂化泛函HSE06方法对Fe掺杂α-Bi2 O3的电子结构和光学性质进行了计算研究.结果表明,Fe掺杂α-Bi2 O3体系有较小的结构变形,本征α-Bi2 O3的禁带宽度为2.69 eV,Fe掺杂使α-Bi2 O3的禁带宽度减小(约为2.34 eV).对其光学性质研究得出Fe掺杂扩展了α-Bi2 O3对可...     

钾明矾蓄热性能的研究与改善

钾明矾(KAl(SO4)2·12H2O)有较高的潜热和良好的导热性(熔化热232.4kJ/kg,导热系数为0.55W/m·K),熔点为91℃,是中低温相变材料中较有开发价值的一种.但是它的过冷度高达19.8℃,并且由于相变过程伴随着结晶水的蒸发使无机盐的使用寿命大大降低.本文通过冷指法及添加成核剂的方法对硫酸铝钾的过冷现象进行了研究,结果表明成核剂NiSO4·6H2O、MgCl2·6H2O能较好的改善过冷现象,当MgCl2·6H2O的添加量为2;时可使过冷度降为零,且能保持钾明矾的相变温度而不使其降低.利用MgCl2·6H2O具有很强的吸湿性,可以补充相变过程中损失的水分,使相变材料的使用寿命大大提高.     

陶瓷材料疏水性能的研究进展

本文简述了疏水性表面的基本原理,分别从低表面能物质修饰和表面微细粗糙结构的构建两个方面,对疏水性陶瓷材料的制备技术和最新的成果进行了总结,介绍了其潜在的应用并对未来的研究方向作了展望.     

铷原子中参量六波混频和量子拍的研究

在铷原子中实现了轴向相位匹配的参量六波混频,并探测到位于红外光谱区的六波混频信号.六波混频信号与泵浦激光进行和频,产生了位于可见光范围内的可调谐的和频信号,并从和频信号中观察到频率为608 cm 1的量子拍.结果表明,六波混频信号中的量子拍能够用于研究原子和分子的相干特性.     

Faraday-Michelson system for quantum cryptography

Quantum key distribution provides unconditional security for communication. Unfortunately, current experimental schemes are not suitable for long-distance fiber transmission because of phase drift or Rayleigh backscattering. In this Letter we present a unidirectional intrinsically stable scheme that is based on Michelson-Faraday interferometers, in which ordinary mirrors are replaced with 90 degree Faraday mirrors. With the scheme, a demonstration setup was built and excellent stability of interference fringe visibility was achieved over a fiber length of 175 km. Through a 125 km long commercial communication fiber cable between Beijing and Tianjin, the key exchange was performed with a quantum bit-error rate of less than 6%, which is to our knowledge the longest reported quantum key distribution experiment under field conditions.     

单层2H-MoTe2光电效应的理论研究

材料的禁带宽度是影响光电探测器探测范围的重要因素.单层2H-MoTe2因具有合适的禁带宽度引起了科研人员广泛的研究兴趣.本文基于非平衡态格林函数-密度泛函理论,采用第一性原理方法,研究了单层2H-MoTe2的光电效应.结果表明:在线性偏振光照射下,MoTe2产生的光电流函数与唯象理论相吻合;在光子能量范围1.6～1.8...     

异戊醇萃取-原子荧光光谱法间接测定中草药中铜含量

提出了一种原子荧光光谱法间接测定中草药中铜含量的方法。在弱酸性介质中,CuI与HgI42-反应生成稳定的Cu2HgI4,经异戊醇萃取分离后,通过用原子荧光光谱法测定有机相中剩余的汞量,间接换算成铜含量。铜的质量浓度在0.01～0.1mg.L-1范围内与荧光强度呈线性关系,方法的检出限(3S/N)为3.5μg.L-1。方法用于国家标准物质黄芪(GSB-19)、茶叶(GSB-7)和柑橘叶(GSB-11)的分析,测定值与认定值相符,测定值的相对标准偏差(n=9)在0.8%～2.4%之间。     

Multireference calculations on low-lying states and the X~3 Π_u -~3 Π_g absorption spectra of indium dimers

Multireference configuration interaction calculations are carried out on 11 Λ-S low-lying electronic states of indium dimers. The states are investigated with spin-orbit pseudopotentials via the state-interacting method, and characterized by fitted spectroscopic constants based on computed potential energy curves. The vibrational structures of the double-potential well 0+g (I) ( 3 Σ g ) state are also analyzed. The experimentally observed absorption spectrum centred at ～ 13000cm-1 is simulated and assigned to X 3 Πu (v=0)-3Πg transition according to the present ab initio calculations on transition energies and dipole moment functions.     

Magnetic properties and magnetocaloric effects in amorphous and crystalline Gd55Co35Ni10 ribbons

The magnetic properties and magnetocaloric effects of amorphous and crystalline Gd55Co35Ni10 ribbons are investigated.A main phase with a Ho 12 Co 7-type monoclinic structure(space group P21/c) and a minor phase with a Ho4Co3-type hexagonal structure(space group P63/m) are obtained for crystalline ribbon after annealing.The amorphous ribbons order ferromagnetically and undergo a second-order transition at 192 K.For crystalline Gd55Co35Ni10 ribbons,two magnetic phase transitions occur at 158 and 214 K,respectively.The peak value of-△SM under a field change of 0-5 T is 6.5 J/kg K at 192 K for amorphous Gd55Co35Ni10 ribbons.A relatively large magnetic entropy change(～5.0 J/kg K) under a field change of 0-5 T for the crystalline Gd55Co35Ni10 ribbons is obtained in the temperature interval range of 154-214 K.The large platform of magnetic entropy change and the negligible thermal/magnetic hysteresis loss mean the crystalline Gd55Co35Ni10 compound can satisfy the requirement of the Ericsson-type refrigerator working in the temperature range from 154K to 214K.