煤的超临界醇萃取脱硫

采用超临界醇萃取脱除煤中的硫。目的是获得洁净、高热值的固体燃料。论述了在煤的超临界醇萃取脱硫过程中，各种含硫化合物的变化与脱除情况；详细介绍了各种操作参数对脱硫效果的影响。     

外电场下氯甲烷的光谱和解离特性

为了研究外电场对氯甲烷分子光谱和解离特性的影响,采用密度泛函理论（density functional theory,DFT）B3LYP方法在6-311++G（d,p）基组水平上研究了不同外电场（-0.03 a.u.~0.03 a.u.）对氯甲烷分子结构以及解离特性的影响,包括键长、分子能隙、红外光谱以及解离势能面等. 计算结果表明,随着Z方向（C-Cl连线方向）外电场从-0.03 a.u.逐渐增加到0.03 a.u., C-Cl键的键长逐渐增大而C-H键的键长几乎不变, 分子能隙EG先增大后减小,当外加电场等于0.01 a.u.时达到峰值. C-Cl 伸缩（stretching, STR） 振动的频率是逐渐减小的, 而红外光谱（infrared,IR）振动强度是逐渐增加的. 通过进一步计算研究发现, 随着外电场（0~0.03 a.u.）继续增强, CH3Cl分子的势能曲线逐渐降低, 解离能逐渐减小. 当外电场大约是0.04 a.u.时解离能最小,发生解离. 因此,可以通过改变外电场来控制CH3Cl分子的降解.     

场限环电场分布的有限元分析

矩形场限环在器件反偏时的最大电场总是集中于四角，因而求解柱坐标下极角α不变的泊松方程可使场限环三维电场分布的讨论大为简化．在此基础上用有限元法对三场环结构的电场分布进行模拟，并对结构参数进行了优化分析．环电位随外加电压而变化的模拟结果与实验结果相吻合，表明了简化模型和分析方法的正确性和实用性．     

组合外加电场提高Fe∶LiNbO_3中90°记录体全息的衍射效率

针对90°全息记录结构的特殊性,在记录和读出阶段分别施加不同极性的外加电场,实现了Fe∶LiNbO3晶体中高衍射效率的全息记录和读出。在库赫塔列夫(Kukhtarev)方程基础上引入两维耦合波理论,对组合外加电场提高掺铁铌酸锂晶体光折变特性的机理进行了探讨。实验和理论计算结果都表明这种分别在记录和读出过程施加不同极性组合的外加电场是在Fe∶LiNbO3中实现高衍射效率90°记录结构体全息的有效技术方案。     

组合外加电场提高Fe:LiNbO3中90°记录体全息的衍射效率

针对90°全息记录结构的特殊性,在记录和读出阶段分别施加不同极性的外加电场,实现了Fe:LiNbO3晶体中高衍射效率的全息记录和读出.在库赫塔列夫(Kukhtarev)方程基础上引入两维耦合波理论,对组合外加电场提高掺铁铌酸锂晶体光折变特性的机理进行了探讨.实验和理论计算结果都表明这种分别在记录和读出过程施加不同极性组合的外加电场是在Fe:LiNbO3中实现高衍射效率90°记录结构体全息的有效技术方案.     

外加电场和磁场对太赫兹辐射产生的影响

通过对半导体太赫兹发射极在有和没有外加电场和磁场作用下发射光谱的测量。说明了外加电场和磁场对太赫兹电磁辐射的产生具有增强作用。采用反射式发射极在飞秒激光作用下辐射太赫兹脉冲的装置，同时利用电光取样方法探测太赫兹电场，得到了这些发射极的时域发射光谱，并通过快速傅里叶变换(FFT)得到了相应的频域光谱。实验表明，太赫兹时域发射光谱和频谱在外加电场、磁场作用下都有增强，但是所发射的频率成分和带宽都没有改变。借助于经典电磁理论的定性分析，认为太赫兹发射光谱在外加电场、磁场作用下的增强起源于半导体中载流子的加速运动受外加电场和磁场的影响。     

用外加电场来控制还原LiNbO_3的光损伤

本文研究了还原LiNbO_3的折射率损伤(光损伤)的磁化率和光电导性间的关系和外加电场的效应。光电流量与折射指数变化成正比。光电流和光损伤随外加电场而变化,取决于固有的内电场。引起光损伤的固有电场值已从光电流外推和折射率变化与外加电场曲线之关系作出估计。其结果是,用加外电场的办法能容易地控制还原LiNbO_3的光损伤。     

微波辐射氧化法联合脱除煤中有机硫的研究

研究了微波辐射冰醋酸和过氧化氢氧化法联合脱除原煤中有机硫的技术。采用单因子法考察了微波照射时间、微波照射功率、煤的粒度、煤与氧化剂的配比、冰醋酸与过氧化氢配制比等因素对脱硫率的影响 ,优选出了微波氧化联合法脱除原煤中有机硫的最佳工艺条件为 :微波功率为 85 0W ,照射时间为 2 0min ,煤与氧化剂的配比为 3g :5 0mL ,煤的粒度为d≤ 0 .2 3mm ,冰醋酸与过氧化氢的体积比为 1:1(摩尔比为 11.5 :38.5 ) ,脱硫率可达到6 0 .2 %。结果表明微波辐射下冰醋酸与过氧化氢氧化法是脱除原煤中有机硫的一种有效方法。     

电场对负性介电常数各向异性的小分子胆甾相液晶的作用

介绍和总结了边界条件影响很大的受限胆甾相和聚合物分散小分子胆甾相液晶（PDCLC）两种情况下，外电场对负性介电常数各向异性的小分子胆甾相液晶的作用。前者的研究通过在不变螺距p情况下改变液晶盒鹌鹑d与外电场电压值E，发现了规律性变化的液晶相的相态结构。而对PDCLC的研究中，通过平行和垂直于电场方向的观察，得到了胆甾相变化与外加电压的具体关系，以及在彩色液晶显示上应用。     

电泡模型研究

基于铁电体物理学的基本理论，研究了在外加电场中铁电薄膜的电畴结构。研究表明，在铁电材料为单轴各向异性薄膜，且在铁电薄膜中能够形成电畴的情形下，如果外加一定大小的电场，同时外加电场的方向与将要形成的电畴的预定极化方向相反的条件下，在铁电薄膜中就可以形成圆柱形电畴结构，称为电泡。本质上，电泡是铁电薄膜中电畴所承受的压缩力与扩张力稳定平衡的结果，是电畴的一种稳定结构。至于电泡尺度的大小，除了与外加的电场有关外，还应与所研究的材料有关。     

Modification of the electric properties of molecular devices via gradual increase of number of nitrogen atoms: A computational study

This paper introduces a new means to manipulate electronic structures and, consequently, the electrical properties of molecular devices via gradual increase of number of nitrogen atoms in the backbone of conjugated organic molecular systems. Diblock molecules were selected for this purpose. Density functional theory (DFT) was used to investigate geometrical and electronic structures in the absence and presence of external electric field. Furthermore, the tendency of the anchor sulfur atoms toward electrodes in a simulated closed circuit was estimated from the relative condensed Fukui function. The obtained results indicated that HOMO–LUMO gap decreases steadily with increasing the number of nitrogen atoms, which would be used as a means for modifying the electrical properties in a regular mode.     

Electric Field Controlled Self‐Assembly of Hierarchically Ordered Membranes

Self‐assembly in the presence of external forces is an adaptive, directed organization of molecular components under nonequilibrium conditions. While forces may be generated as a result of spontaneous interactions among components of a system, intervention with external forces can significantly alter the final outcome of self‐assembly. Superimposing these intrinsic and extrinsic forces provides greater degrees of freedom to control the structure and function of self‐assembling materials. In this work we investigate the role of electric fields during the dynamic self‐assembly of a negatively charged polyelectrolyte and a positively charged peptide amphiphile in water leading to the formation of an ordered membrane. In the absence of electric fields, contact between the two solutions of oppositely charged molecules triggers the growth of closed membranes with vertically oriented fibrils that encapsulate the polyelectrolyte solution. This process of self‐assembly is intrinsically driven by excess osmotic pressure of counterions and the electric field is found to modify the kinetics of membrane formation as well as membrane morphology and properties. Depending on the strength and orientation of the field we observe a significant increase or decrease of up to nearly 100% in membrane thickness, or the controlled rotation of nanofiber growth direction by 90 degrees which leads to a significant increase in mechanical stiffness. These results suggest the possibility of using electric fields to control structure in self‐assembly processes that involve the diffusion of oppositely charged molecules.     

激光与电场在滇稻育种中的微观作用机制分析比较

用激光加电场进行育种研究 ,发现静电场和激光的作用效果是不相同的。这反映了它们与生物组织的相互作用机制的差异。本文用量子力学对此差异进行了解析分析 ,并与育种试验结果进行印证。得出电场辐照种子 ,可降低蛋白质分子的能级 ,增加种子的生物活性 ;激光辐照种子 ,有可能使DNA的构象发生变化 ,从而引起一定程度上的变异     

长脉冲GW级HPM大气击穿时间分析

结合电子流体方程与Maxwell方程组,对单脉冲高功率微波(HPM)大气击穿过程进行仿真,采用时域有限差分方法(FDTD)并结合HPM自生等离子体的特征参数,仿真了不同压强和场强下单脉冲HPM自生等离子体的参量变化,分析了HPM频率为6.4 GHz时,不同场强、压强下的大气击穿时间,并开展了大气击穿实验加以验证。理论分析与实验结果表明,实验与理论分析结果一致,压强与场强的变化对大气击穿时间均有显著影响,原因在于场强和压强对大气击穿种子电子浓度的变化起决定性作用,进而影响大气击穿时间。场强为kV/cm量级时,大气击穿时间在10 ns量级,在相同的场强下,随着压强的增大,击穿时间会先减小再增加。相同的大气压强条件下,场强越高,大气击穿时间越短。     

Modulation of conduction at points of axonal bifurcation by appliedelectric fields

This study investigated how weak electric fields, on the order of 100 mV/cm, modulate action potential conduction through points of axonal bifurcation in leech touch sensory neurons. Axonal branch points in neurons are ubiquitous structures, and they are sites of low safety-factor for action potential propagation. In this study calibrated electric fields were applied around excised ganglia from the leech central nervous system. The electric fields were generated by 500 ms constant current square waves applied to the bath containing the tissue. Microelectrode penetration of the neurons was used to: 1) record transmembrane potential changes in the cell body of the neuron that resulted from the external field; 2) monitor conduction block when action potentials, evoked in the periphery, propagated into the ganglion; 3) inject current directly into the cell in an experimental analysis of the mechanism by which the externally applied field produced block. Conduction block was reliably induced by electric fields too weak to reach threshold for firing action potentials. In an experimental analysis where block was produced by the direct intracellular injection of negative current, a reversed polarity field relieved it. This indicates that when the external field induces block, it does so by membrane hyperpolarization at the branch point.     

C60在Ag(111)表面的STM图像理论模拟

本文利用离散变分和局域密度泛函（ＤＶ－ＬＤＦ）方法,通过计算Ｃ６０／Ａｇ（１１１）的电荷密度分布图,即模拟出该体系的ＳＴＭ图像,并详细地研究了体系的电子结构,结果表明,该体系中有２．３２ｅ自金属表面Ａｇ原子向Ｃ６０转移。外电场的极性对图像影响委 正偏压情形,ＬＵＭＯ电荷密度分布图为三个五边形围成则呈三叶状,反映的是体系中吸附分子的对称性,且隧道电流主要来自单键。而ＨＯＭＯ电荷密度分布图具有三重对称     

小型无线场强探测传感器研究

近年来,微波加热因其高效性和清洁无污染等优点广泛应用于各个领域.然而,微波加热的不均匀性限制了微波作为高效加热能源的应用.通过测量和分析加热腔中的电场分布情况可以帮助设计人员改进微波加热腔体设计,提高微波加热的均匀性.现有的场强测量设备均为有线设备,应用场景极为有限.因此,本文提出了一种由探头、接收机和上位机三部分组成...     

Influence of Electric Field on Microstructures of Pentacene Thin‐Films in Field‐Effect Transistors

We report on electric‐field‐induced irreversible structural modifications in pentacene thin films after long‐term operation of organic field‐effect transistor (OFET) devices. Micro‐Raman spectroscopy allows for the analysis of the microstructural modifications of pentacene in the small active channel of OFET during device operation. The results suggest that the herringbone packing of pentacene molecules in a solid film is affected by an external electric field, particularly the source‐to‐drain field that parallels the a–b lattice plane. The analysis of vibrational frequency and Davydov splitting in the Raman spectra reveals a singular behavior suggesting a reduced separation distance between pentacene molecules after long‐term operations and, thus, large intermolecular interactions. These results provide evidence for improved OFET performance after long‐term operation, related to the microstructures of organic semiconductors. It is known that the application of large electric fields alters the semiconductor properties of the material owing to the generation of defects and the trapping of charges. However, we first suggest that large electric fields may alter the molecular geometry and further induce structural phase transitions in the pentacene films. These results provide a basis for understanding the improved electronic properties in test devices after long‐term operations, including enhanced field‐effect mobility, improved on/off current ratio, sharp sub‐threshold swing, and a slower decay rate in the output drain current. In addition, the effects of source‐to‐drain electric field, gate electric field, current and charge carriers, and thermal annealing on the pentacene films during OFET operations are discussed.     

Electronic structure of C60 adsorbed on Ag(111) surface and its STM images

The electronic structure of C₆₀ adsorbed on Ag(111) surface have been calculated by using Discrete Variational-Local Density Functional method(DV-LDF).The STM images have been obtained by calculating the charge density distributions of the system,which based on the Tersoff-Hamann theory.The results show that there is 2.32e transfer from Ag cluster surface to C₆₀.The STM images are sensitive to the polarity of external electric field.In the positive bias voltage case,there is three five-membered rings around the topmost in the calculated charge distribution of LUMO and it reflects the symmetry of adsorbed molecular.This means that the tunneling current come mainly from the single bond.However,in the negative bias case,the STM image show that the topmost six-membered ring is highlighted with a center hole just like a doughnut.We find a good agreement between the STM images observed and the calculated charge distributions of HOMO and LUMO.