角向周期结构静电电子回旋脉塞

提出了一种角向周期结构静电电子回旋脉塞的方法。用流体线性理论导出了这种脉塞的色散方程和增长率公式,并进行了相应的分析与计算。此结构能较好地克服正常同轴波导静电电子回旋脉塞工作频率难以提高的困难,并且该结构中的多种角向梯式时提高工作频率和电子注效率是一个良好的途径。

MGC—I型无静磁场电子自旋共振仪

MGC—I型无静磁场电子自旋共振仪是在文献[1]的理论基础上，把传统的电子自旋共振仪中的静磁场省掉，使电子自旋共振理论和技术推广到交变磁场中而研制的一种仪器。为了发展和开发电子自旋共振技术在其他学科应用的断领域。本文在叙述这种仪器的设计原理与设计结构的同时。还对电子自旋共振技术作了进一步的介绍。

基于MPI+CUDA环境的静电相互作用能并行求解

ABEEMσπ(Atom-Bond Electronegativity EqualizationσπModel)模型中,原串行程序求静电相互作用能的方法非常耗时,致使研究问题的效率降低。针对原程序中多个循环相互嵌套的求解部分,采用带状卷帘存储迭代分配的MPI(Message Passing Inter-face)并行化处理;对体系中所有原子、σ键、孤对电子、π键位点之间的静电相互作用能采用多线程CUDA(Computer Unified DeviceArchitecture)并行化处理。传统MPI+CUDA环境中,GPU和CPU之间的数据传输开销大,导致整体性能下降以及各种粒子间计算串行调用CUDA,致使时间浪费。针对上述情况,使用GPU核心的缓存机制解决传输开销大的问题,并利用多CUDA流技术实现多个循环异步进行计算,从而缩短了运行时间。然后选取多个不同类型的大分子体系进行测试,结果表明,利用改进的MPI+CUDA并行模型进行动力学模拟,并行加速比显著提高,大幅度缩减了求解静电相互作用能的时间,并得到与串行一致的结果。

等效模型在静电学中的一种应用

本文通过用等效模型求解一例静电学问题，阐明在普物教学中，应重视用等效模型或等效方法来解决一些通常方法很难解决甚至无法解决的问题．

关于带电粒子静质量数的经验公式

本文通过对两个无量纲常数的讨论认为电子静质量数的大小是由所参予的三种作用决定的，并且由电子静质量数表达式出发导出的重粒子与电子的静质量比值与实验结果符合得很好。

Mechanism of Reverse Snapback on I-V Characteristics of Power SITHs with Buried Gate Structure

The reverse snapback phenomena （RSP） on I-V characteristics of static induction thyristors （SITH） are physically researched. The I-V curves of the power SITH exhibit reverse snapback phenomena, and even turn to the conducting-state,when the anode voltage in the forward blocking-state is increased to a critical value. The RSP I-V characteristics of the power SITH are analyzed in terms of operating mechanism, double carrier injection effect, space charge effect, electron-hole plasma in the channel, and the variation in carrier lifetime. The reverse snapback mechanism is theoretically pro- posed and the mathematical expressions to calculate the voltage and current values at the snapback point are presented. The computing results are compared with the experiment values.

Improvements on High Current Performance of Static Induction Transistor

Methods for improving the high current performance of static induction transistor （SIT） are presented.Many important factors,such as ＂trans-conductance per unit channel width＂ θ, ＂gate efficiency＂ η, ＂sensitivity factor＂ D,and ＂intrinsic static gain＂ μ0,that may be used to describe different aspects of the electrical performance of an SIT are first defined.The dependences of electrical parameters on the structure and technological process of an SIT are revealed for the first time.The packaging technologies are so important for the improvement of high power performance of SITs that they must be paid attention.Testing techniques and circuits for measuring frequency and power parameters of SITs are designed and constructed.The influence of packaging processes in technological practice on the electrical performance of SITs is also discussed in depth.

The Bipolar Field-Effect Transistor:V.Bipolar Electrochemical Current Theory(Two-MOS-Gates on Thin-Base)

This paper reports the intrinsic-structure DC characteristics computed from the analytical electrochemical current theory of the bipolar field-effect transistor （BiFET） with two identical MOS gates on nanometer-thick pure-base of silicon with no generation-recombination-trapping. Numerical solutions are rapidly obtained for the three potential variables,electrostatic and electron and hole electrochemical potentials,to give the electron and hole surface and volume channel currents,using our cross-link two-route or zig-zag one-route recursive iteration algorithms. Boundary conditions on the three potentials dominantly affect the intrinsic-structure DC characteristics,illustrated by examples covering 20-decades of current （10-22 to 10-2 A/Square at 400cm^2/（V · s） mobility for 1.5nm gate-oxide, and 30nm-thick pure-base）. Aside from the domination of carrier space-charge-limited drift current in the strong surface channels,observed in the theory is also the classical drift current saturation due to physical pinch-off of an impure-base volume channel depicted by the 1952 Shockley junction-gate field-effect transistor theory,and its extension to complete cut-off of the pure-base volume channel,due to vanishing carrier screening by the few electron and hole carriers in the pure-base,with Debye length （25mm） much larger than device dimension （25nm）.

Quasi-static and dynamic tensile behaviors in electron beam welded Ti-6Al-4V alloy

The quasi-static and dynamic tensile behaviors in electron beam welded（EBW） Ti-6Al-4V alloy were investigated at strain rates of 10-3 and 103 s-1,respectively,by materials test system（MTS） and reconstructive Hopkinson bars apparatus.The microstructures of the base metal（BM） and the welded metal（WM） were observed with optical microscope.The fracture characteristics of the BM and WM were characterized with scanning electronic microscope.In Ti-6Al-4V alloy joint,the flow stress of WM is higher than that of BM,while the fracture strain of WM is less than that of BM at strain rates of 103 and 10-3 s-1,respectively.The fracture strain of WM has apparent improvement when the strain rate rises from 10-3 to 103 s-1,while the fracture strain of BM almost has no change.At the same time,the fracture mode of WM alters from brittle to ductile fracture,which causes improvement of the fracture strain of WM.

Ionic Distribution, Electrostatic Potential and Zeta Potential at Electrochemical Interfaces

Density functional theory is applied to predicting the structures and electrostatic potentials of planar electrochemical surfaces within the framework of the restricted primitive model where small ions are represented by charged hard spheres of equal diameter and the solvent is assumed to be a continuous dielectric medium. The hard-sphere contribution to the excess Helmholtz energy functional is evaluated using the modified fundamentalmeasure theory and the electrostatic contribution is obtained from the quadratic functional Taylor expansion using the second-order direct correlation function from the mean-spherical approximation. Numerical results for the ionic density profiles and the mean electrostatic potentials near a planar surface of various charge densities are in excellent agreement with molecular simulations. In contrast to the modified Gouy-Chapman theory, the present density functional theory correctly predicts the second layer formation and charge inversion of charged surfaces as observed in simulations and in experiments. The theory has also been tested with the zeta potentials of positively charged polystyrene particles in aqueous solutions of KBr. Good agreement is achieved between the calculated and experimental results.

Effect of Potassium Oleate on Rheological Behavior of Cationic Guar in Aqueous Solution with Varying Temperatures

The rheology of the cationic guar （CG） solution was measured and the effects of potassium oleate （KOA） upon the rheological properties of CG solution were studied. The steady shear viscosity measurement has shown that the viscosity of CG solution increased dramatically in the presence of KOA. The viscosity enhancement of KOA upon CG solution can be approximate three orders in magnitude. The gel-like formation of CG solution is observed at the high concentration of KOA. The excess addition of KOA results in the phase separation of CG solution. The oscillatory rheological measurement has shown that the crossover modulus Gc （corresponding to either storage modulus G＇ or loss modulus G＇＇ at the frequency wc where G＇ equals G＇＇） for CG solution, decreases with the increasing the concentration of KOA in solution. On the other hand, the apparent relaxation time 7-app （=1/wc） increases with increasing the concentration of KOA in solution. Our experimental results suggest that for surfaetant such as KOA which has a stronger tendency to form micelles in solution, the cooperative hydrophobic interaction of polymer bound to surfactants is less necessary to the formation of aggregates in solution, especially at the high concentration of surfactants. In fact, with the increase of the concentration of KOA, the number of the aggregates which associate polymer together decreases whereas the intensity of these aggregates increases. The effect of temperature upon the aggregation is also significant. With the increase of temperature, the number of the aggregates increases whereas the intensity of these aggregates decreases, probably because the ionization of KOA increases at high temperature.

Pneumatic resistance network analysis and dimension optimization of high pressure electronic pneumatic pressure reducing valve

The structure and working principle of a self-deigned high pressure electronic pneumatic pressure reducing valve (EPPRV) with slide pilot are introduced.The resistance value formulas and the relationship between the resistance and pressure of three typical pneumatic resistances are obtained.Then,the method of static characteristics analysis only considering pneumatic resistances is proposed,the resistance network from gas supply to load is built up,and the mathematical model is derived from the flow rate formulas and flow conservation equations,with the compressibility of high pressure gas and temperature drop during the expansion considered in the model.Finally,the pilot spool displacement of 1.5 mm at an output pressure of 15MPa and the enlarging operating stroke of the pilot spool are taken as optimization targets,and the optimization is carried out based on genetic algorithm and the model mentioned above.The results show that the static characteristics of the EPPRV are significantly improved.The idea of static characteristics analysis and optimization based on pneumatic resistance network is valuable for the design of pneumatic components or system.

Luminal oxidants selectively modulate electrogenic ion transport in rat colon

AIM： To investigate the effects of luminal exposure to H2O2 and two related thiol oxidizing agents on basal and stimulated chloride secretion in native colon using electrophysiological and pharmacological approaches. METHODS： Unstripped rat distal colon segments were mounted in Ussing chambers. Potential difference, calculated resistance and short-circuit current across unstripped colon segments were monitored with a dual voltage/current clamp. Paracellular permeability was assessed by measuring the mucosa-to-serosa flux of a fluorescent probe （FITC）. RESULTS： Luminal exposure to hydrogen peroxide transitorily stimulated chloride secretion without altering barrier function. This stimulatory effect could be blocked by basolateral atropine but not indomethacin. The cysteine and methionine oxidizing compounds, phenylarsine oxide and chloramine T respectively, mimicked the effect of H2O2, except for a drop in transcolonic resistance after 30 min. In contrast to the observed stimulatory effect on basal secretion, cAMP-stimulated electrogenic ion transport was blunted by luminal H2O2. However, the Ca^2＋- activated response remained unchanged. CONCLUSION： H2O2 may be an important selective modulator of intestinal ion and water secretion in certain pathologic conditions such as inflammation or ischemiareperfusion by multiple mechanisms.

Tracking charge transfer pathways in SrTiO_(3)/CoP/Mo_(2)C nanofibers for enhanced photocatalytic solar fuel production

Photocatalytic solar fuel generation is currently a hot topic because of its potential for solving the energy crisis owing to its low cost and zero-carbon emissions.However,the rapid bulk recombination of photoexcited carrier pairs is a fundamental disadvantage.To resolve this problem,we synthesized a dual cocatalysts system of cobalt phosphide(Co P)and molybdenum carbide(Mo_(2)C)embedded on strontium titanate(Sr TiO_(3))nanofibers.Compared with those of pristine SrTiO_(3) and binary samples,the dual cocatalysts system(denoted SCM)showed a significant improvement in the hydrogen evolution and CO_(2) reduction performance.Further,the structure of SCM effectively promoted spatial charge separation and enhanced the photocatalytic performance.In addition,the Schottky junction formed between the SrTiO_(3) and cocatalysts enabled the rapid transfer of photoexcited electrons from SrTiO_(3) to the cocatalysts,resulting in effective separation and prolonged photoexcited electron lifetimes.The electron migration route between SrTiO_(3) and the cocatalysts was determined by in situ irradiation X-ray spectroscopy,and band structures of Sr TiO_(3) and the cocatalysts are proposed based on results obtained from UV-vis diffraction reflection spectroscopy and ultraviolet photoelectron spectroscopy measurements.On the basis of our results,the dual cocatalysts unambiguously boosts charge separation and enhances photocatalytic performance.In summary,we have investigated the flux of photoexcited electrons in a dual cocatalysts system and provided a theoretical basis and ideas for subsequent research.

Novel fluorescence sensor based on covalent immobilization of 3-amino-9-ethylcarbazole via electrostatically assembled gold nanoparticle layer

A novel technique of immobilizing indicator dyes by electrostatic adsorption and covalent bonding to fabricate optical sensors was developed.3-Amino-9-ethylcarbazole(AEC)was attached to the outmost surface of quartz glass slide via aminosilanizing the slide,crosslinking chitosan,adsorbing Au nanoparticle,self-assembling HS(CH2)11OH,and coupling AEC.Thus, an AEC-immobilized optical sensor was obtained.The sensor exhibits a wide linear response range from 7.0×10- 7to 1.0×10 -4 mol/L and a correlation coefficient of 0.995 9 for the detection of 2-nitrophenol.The detection limit and response time of the sensor are 1.0×10- 7mol/L and less than 10 s,respectively.The fluorescence intensity of the used sensor can be restored to the blank value by simply rinsing with blank buffer.A very effective matrix for immobilizing indicator dye is provided by the proposed technique, which is adaptable to other indicator dyes with amino groups besides AEC.

Collapse of Four-Arm Stars Polyelectrolyte Brushes Under An Electric Field in the Presence of Trivalent Salt Coions

Langevin dynamics simulations were conducted to study the collapse of grafted partially charged 4-arm star chains onto the oppositely charged grafting electrode in the presence of trivalent salt coions.Simulation results reveal that the average charge fraction of the grafted star chains and the salt concentration play critical roles in the competitive adsorption of charged monomers and trivalent salt coions onto the oppositely charged electrode.For grafted star chains with relatively high charge fraction,charged monomers are the dominant species collapsing on the oppositely charged electrode with the emergence of charge reversal on the grafting electrode.At a low charge fraction such that the total amount of charges on a grafted star molecule is comparable to that of a trivalent salt coion,trivalent salt coions absorb more strongly onto the electrode than grafted stars even at very low salt concentration.It is found that at relatively low charge fraction of star chains,the addition of trivalent salt coions does not lead to charge overcompensation of the surface charges on the grafting electrode.The stretching of star brushes under an electric field in the presence of trivalent salt coions was also briefly investigated.

A PHOTOEMISSIVE MONOENERGETIC ELECTRON SOURCE FOR CALIBRATING THE BETA－MAGNETIC SPECTROMETER

A new kind of electron source, the photoemissive monoenergetic electron source has been invented for calibrating the beta--magnetic spectrometer. It produceselectrons in the form of simulating a radioactive monoenergetic electron source andcan be made in any shape and size according tO the demands of experimentS. In thispaper, the principles and basic constructions of the photoemissive monoenergeticelectron source are described, the resultS of calibrating our 2’l’x bead--magneticspectrometer with a single strip arc shaped photoemissive monoenergetic electronsource are listed, a new way for determining resolution function of experimentslsystem in the research of neutrino rest mass has been posed and one of its actualapplications is also given.

Preparation of dual-shell Si/TiO_(2)/CFs composite and its lithium storage performance

A dual-shell Si/TiO2/CFs composite was synthesized through a simple method to deal with the intrinsic drawbacks of silicon-based anode,in terms of huge volume change,unstable SEI films,and low electronic and ionic conductivity.The inner rigid TiO2 shell alleviates the huge volume expansion of the nano silicon,and the outer resilient carbon fiber,which is porous and staggered,is beneficial to the rapid transport of electrons and ions.The as-prepared Si/TiO2/CFs composite displays a superior reversible specific capacity of 583.4 mA·h/g,high rate capability and decent cycling performance.The dual-shell encapsulation method provides a guideline for other anode materials with huge volume expansion during the cycling process.

A New Fine Damping Method for Solid ESG Rotor

For the electrostatically suspended gyro （ESG） with solid rotor, because the equatorial photoelectric sensor won＇t sense the equatorial marking line and output the correct damping control information when the nutation angle is small, the active damping with equatorial marking line will bring considerable error. The passive damping method by applying strong DC magnetic field requires too much time. So an active damping method by longitude marking lines is proposed to fulfill the fine damping for solid ESG rotor. The shape of rotor marking lines and the principle of fine damping are introduced. The simulation results prove that this fine damping method can effectively solve the problem of damping error introduced by active damping with equatorial marking line. The estimating resuits for damping time indicate that the fine damping time is less than 10 percent of passive damping time.