A fast fourier transform method for calculating the equilibrium density matrix

We calculate the low-temperature quantum density matrix by integrating numerically the Bloch equation. The initial condition is the classical high-temperature value of the density matrix. The integration method uses short “time” propagators computed by a fast Fourier transform method.     

Ambient pressure superconductivity at 4–5 K in β-(BEDT-TTF)2AuI2

Crystals of β-(BEDT-TTF)₂AuI₂, derived from the sulfur-based organic donor bis(ethylenedithio) tetrathiafulvalene [BEDT-TTF or “ET”] have been synthesized by electrocrystallization and studied by rf penetration depth measurements at ambient pressure and at temperatures down to 0.45 K. The crystals were found to be superconducting at ambient pressure with T_c = 3.93–4.98 K, which represent the highest values of T_c thus far observed at ambient pressure for an organic superconductor. Measurements of the upper critical field anisotropy are reported.     

Characterization of a low-temperature form of InVO4

A low-temperature form of InVO₄, belonging to the α-MnMoO₄ structural type, was characterized. The unit cell parameters were determined from X-ray powder diagrams. The infrared spectrum was discussed with the aid of a “site-symmetry analysis.” The results were discussed in comparison with those of the corresponding high-temperature form (CrVO₄ type) and with some other related compounds.     

Facile selective aminolysis of phenolic benzoates with 1-butanamine in benzene

1-Butanamine in benzene at room temperature effects selective aminolysis of phenolic benzoates without affecting aliphatic benzoates     

大功率单脉冲超声信号发生器的设计

为了提高探伤深度,实现混凝土大坝等散射强介质的超声检测,本文提出了一种成本低,小体积,结构简单的大功率单脉冲超声信号发生器,并给出了原理电路设计。所述装置利用控制电容充放电经脉冲变压器产生瞬时高压脉冲的新思路,克服了过去由于信号幅度限制功率上不去的困难。经实验验证该装置与现有的单脉冲信号发生器相比,探伤深度得到了很大提高,可用于混凝土结构构建的超声探伤。     

不同连接方案下垂直场线圈的性能研究

基于热-结构耦合分析了欧姆热和等离子体辐照引起的垂直场线圈的温度变化,对垂直场线圈在不同连接方式下的电气参数进行了研究,提出了一种优化的线圈连接方案.计算结果表明,该优化方案有助于改善垂直场线圈的响应性能,并提高其对等离子体的控制能力.     

玉米淀粉固态电解质质子\电子杂化突触晶体管

随绿色可持续发展观念的深入人心,研究人员致力于寻找天然有机材料应用于功能性电子器件.淀粉以其低廉的价格、丰富的来源和优异的机械性能进入了科研人员的视野.淀粉可由玉米、马铃薯、甘薯和葛根等含淀粉的物质中提取而得,一般不溶于水,在和水加热至一定温度时,则糊化成胶状溶液.本文通过旋涂法将玉米淀粉的胶状溶液旋涂至氧化铟锡玻璃表面,然后在30?C恒温环境中晾干制备成固态胶合状薄膜.以此薄膜作为固态电解质制备了氧化铟锌突触晶体管,并实现了生物神经突触的双脉冲易化、学习记忆能力、高通滤波等可塑性行为的仿真.本研究以玉米淀粉固态胶合薄膜作为电解质大大降低了氧化物薄膜晶体管固态电解质的成本,且该电解质无毒性、来源丰富,将为人工神经网络的开发提供一种可选择的元件.     

Influence of structural defects on the optical properties of strongly coupled Au nanoshell arrays

The effects of different defects on optical properties and plasmon resonances properties of Au nanoshell arrays were investigated by using the finite-difference time-domain(FDTD) theory.It is found that the optical properties of the nanoshell arrays are strongly influenced by different defects.We show that when the hollow Au nanoshell arrays are placed in air,there is a wide photonic band gap(PBG) in the infrared region,but the band gap becomes narrower as we introduced different defects.Based on the distributions of electric field component E z and the total energy distribution of the electric and the magnetic field,we show that there exhibit dipoles field distributions for the plasmon mode at the long-wavelength edge of the band gap,but composite higher order modes are excited at the short-wavelength edge of the band gap.The plasmon resonant modes also can be controlled by introducing defects.     

Dielectric loss of half-doped manganite Lao.sCao.sMnO3＊

The dielectric loss tanfi of half-doped manganite Lao.sCao.sMnO3 is investigated using Green＇s function technique. The Lao.sCao.sMnO3 is described by the Kondo-lattice model in the double exchange limit, taking into account the Jahn- Teller distortion and the super-exchange interaction between the localized electrons. It is found that the intensity of tans decreases with increasing [e]TI, V, and U. It is also observed that the transition temperature Tp rises as l eJTI and U increase. It is worth noting that Tp remains unchanged and the strength of tans increases with increasing g. The calculated dielectric loss results are explained theoretically, and these behaviors are in qualitative agreement with the experimental results.