Current-voltage characteristics of individual conducting polymer nanotubes and nanowires

We report the current-voltage (I-V) characteristics of individual polypyrrole nanotubes and poly(3,4-ethylenedioxythiophene) (PEDOT) nanowires in a temperature range from 300 K to 2 K. Considering the complex structures of such quasi-one-dimensional systems with an array of ordered conductive regions separated by disordered barriers, we use the extended fluctuation-induced tunneling (FIT) and thermal excitation model (Kaiser expression) to fit the temperature and electric-field dependent I–V curves. It is found that the I–V data measured at higher temper-atures or higher voltages can be well fitted by the Kaiser expression. However, the low-temperature data around the zero bias clearly deviate from those obtained from this model. The deviation (or zero-bias conductance suppression) could be possibly ascribed to the occurrence of the Coulomb-gap in the density of states near the Femi level and/or the enhancement of electron-electron interaction resulting from nanosize effects, which have been revealed in the previous studies on low-temperature electronic transport in conducting polymer films, pellets and nanostructures. In addition, similar I-V characteristics and deviation are also observed in an isolated K0.27MnO2 nanowire.     

Ultralight,High Capacitance,Mechanically Strong Graphene-Cellulose Aerogels

With increasing energy demand driving the need for eco-friendly and efficient energy storage technology, supercapacitors are becoming increasingly prevalent in wearable devices because of their portability and stability. The performance of these supercapacitors is highly dependent on the choice of electrode material. The high capacitance and mechanical properties needed for these materials can be achieved by combining graphene’s stable electrical properties with renewable cellulose’s excellent mechanical properties into porous aerogels. In this study, graphene-cellulose hydrogels were prepared by a one-step hydrothermal method, with porous, ultra-light, and mechanically strong graphene-cellulose aerogels then prepared by freeze-drying. These composite aerogels possess excellent mechanical strength and high specific capacitance, capable of bearing about 1095 times the pressure of their own weight. Electrochemical tests show the specific capacitance of these composite aerogels can reach 202 F/g at a scanning rate of 5 mA/cm². In view of their high surface area and fast charge transport provided by their 3D porous structure, graphene-cellulose aerogels have great potential as sustainable supercapacitor electrodes.     

Acoustic phonons transport in a quantum waveguide embedded double defects

By using scattering matrix method, we investigate the acoustic phonons transport in a quantum waveguide embedded double defects at low temperatures. When acoustic phonons propagate through the waveguide, the total transmission coefficient versus the reduced phonon frequency exhibits a series of resonant peaks and dips, and acoustic waves interfere with each other in the waveguide to form standing wave with particular wavelengths. In the waveguide with void defects, acoustic phonons whose frequencies approach zero can transport without scattering. The acoustic phonons propagating in the waveguide with clamped material defects, the phonons frequencies must be larger than a threshold frequency. It is also found that the thermal conductance versus temperature is qualitatively different for different types of defects. At low temperatures, when the double defects are void, the universal quantum thermal conductance and a thermal conductance plateau can be clearly observed. However, when the double defects consist of clamped material, the quantized thermal conductance disappears but a threshold temperature where mode 0 can be excited emerges. The results can provide some references in controlling thermal conductance artificially and the design of phonon devices.     

类氢U91+离子的辐射复合及其辐射退激发过程的理论研究

基于多组态Dirac-Fock理论方法,利用GRASP92和RATIP以及在此基础上最新发展的RERR06程序,对类氢U⁹¹⁺（1s）离子的辐射复合截面以及辐射退激发过程进行了详细的理论研究.系统地计算了具有确定能量的连续电子被处于基态的类氢U⁹¹⁺（1s）离子俘获到nl （1≤n≤8, 0≤l≤6）轨道形成类氦U⁹⁰⁺（1snl）离子的辐射复合截面,并研究了这辐射复合末态退激发谱的相对强度.研究发现,类氢U⁹¹⁺（1s）离子辐射复合到不同轨道的截面随其主量子数的增大而显著减小;同时,辐射复合末态的退激发对Kα谱线的相对强度有重要影响. 关键词： 辐射复合 多组态Dirac-Fock理论方法 辐射退激发     

二氧化硅分子配分函数的研究

在低温20K到高温6000K温度范围内,计算了¹⁶O²⁸Si¹⁶O分子稳定结构的的总配分函数.其中,转动配分函数考虑了离心扭曲修正,振动配分函数采用谐振子近似.把20—6000K的温度范围划分为五区间段,计算的总配分函数在这五个温度区间分别被拟合到一个温度T的四阶多项式,从而在每个区间均得到五个拟合系数.由这些拟合系数就可以快速、准确地获得分子在所研究温度范围内任意温度的总的配分函数. 关键词： 总配分函数 二氧化硅分子 转动配分函数 振动配分函数     

间苯三酚类化合物——鹤草酚的NMR研究

鹤草酚（agrimophol）是从中药仙鹤草（Agrimonia pilosa Ledeb.）根芽石油醚提取物中分离得到的具有显著驱虫活性的一种间苯三酚类化合物. 通过化学方法和波谱分析鉴定了该化合物的结构．采用2D NMR技术完善了文献中的¹H NMR 信号归属,并对其¹³C NMR 信号进行了全归属.     

射流抛光多相紊流流场的数值模拟

 理论分析了射流抛光的紊动冲击射流特点,构建了射流抛光的垂直冲击射流模型和斜冲击射流模型。根据射流抛光冲击射流的特点,比较各种流体模型后,采用RNG k-e 模型应用于射流抛光模型的计算。利用计算流体力学理论的二阶迎风格式对抛光模型方程离散,用SIMPLEC数值计算方法对射流抛光过程的紊动冲击射流和离散相磨粒分布进行数值模拟,得到了射流抛光过程的连续流场和离散相磨粒与水溶液的耦合流场,同时计算出了抛光液射流在工件壁面上的压力、速度、紊动强度、剪切力分布和磨粒体积质量分布,分析了垂直射流抛光模型和斜冲击射流抛光模型紊流流场的特点。     

基于MHD的磁射流抛光中流场的分析与模拟

从理论上分析了磁射流抛光中的磁场与流场的相互作用,构建了磁射流抛光的冲击射流模型,基于磁流体动力学对磁射流抛光过程的紊动冲击射流进行数值模拟,得到了磁射流抛光过程的连续流场和射流在工件壁面上的压力、速度、紊动强度分布。通过比较射流抛光和磁射流抛光的数值计算结果,分析了磁流变效应对射流稳定性的影响,从射流的流场、速度、紊动强度等方面分析射流在磁场中稳定的原因。     

Equal-power 4m-th power sum squeezing of generalized magnetic-field component in vacuum state immiting four-state superposition multimode entangled state light field

By utilizing multimode squeezed states theory, we study the generalized nonlinear equal-power higherpower sum squeezing properties of the generalized magnetic-field component in four-state superposition multimode entangled state light field ｜ψ1^（4）〉q. The state is composed of multimode vacuum state, multimode coherent state and its contrary state, multimode imaginary coherent state. It is found that the state ｜ψ1^（4）〉q is a type of four-state superposition multimode nonclassical light field, and under certain fixed conditions, the generalized magnetic-field component in the state ｜ψ1^（4）〉q can display generalized nonlinear equal-power 4m-th power sum squeezing effects which change periodically.     

Oscillations and Collapses of Proto--Neutron Stars

We examine the oscillation and collapse of a relativistic star, e.g., a proto-neutron star, with an equation of state （EOS） which is Mowly changing as driven by, e.g., losing of thermal energy through radiations. We find that the frequency of the fundamental mode of oscillation （radial） will gradually increase then abruptly drop to zero when the star gets close to the point of instability. We also find that for a wide range of configurations on the unstable branch of equilibrium configurations, the collapse is dominated by one unstable mode.