Synthesis and electrochemical properties of three-dimensional graphene/polyaniline composites for supercapacitor electrode materials

To improve the specific capacitance and rate capability of electrode material for supercapacitors, a three-dimensional graphene/polyaniline(3DGN/PANI) composite is prepared via in situ polymerization on GN hydrogel. PANI grows on the GN surface as a thin film, and its content in the composite is controlled by the concentration of the reaction monomer. The specific capacitance of the 3DGN/PANI composite containing 10 wt% PANI reaches 322.8 F·g-1at a current density of1 A·g-1, nearly twice as large as that of the pure 3DGN(162.8 F·g-1). The capacitance of the composite is 307.9 F·g-1at 30 A·g-1(maintaining 95.4%), and 89% retention after 500 cycles. This study demonstrates the exciting potential of3DGN/PANI with high capacitance, excellent rate capability and long cycling life for supercapacitors.     

Water Gas Shift Reaction： A Monte Carlo Simulation

The water gas shift （WGS） reaction is reacts with water on a catalytic surface a process of industrial importance to form CO2 and H2. We study this In this reaction carbon monoxide reaction with thermal （Langmuir- Hinshelwood） and non-thermal （precursor and Eley-Rideal） reaction mechanisms using the techniques of Monte Carlo computer simulation. The details of surface coverages and production rates are given as a function of CO partial pressure. The diffusion of species on the surface as well as their desorption from the surface is also introduced to include temperature effects. The phase diagrams of the system have been drawn to observe the behaviour of reacting species on the surface. The study reveals that the production rates are higher for non-thermal precursor mechanism and are in agreement with the experimental finding.     

Stable water droplets on composite structures formed by embedded water into fully hydroxylated β-cristobalite silica

Using molecular dynamics simulations, we have revealed a novel wetting phenomenon with a droplet on composite structures formed by embedded water into(111) surface of β-cristobalite hydroxylated silica. This can be attributed to the formation of a composite structure composed of embedded water molecules and the surface hydroxyl(–OH) groups,which reduces the number of hydrogen bonds between the composite structure and the water droplet above the composite structure. Interestingly, a small uniform strain(±3%) applied to the crystal lattice of the hydroxylated silica surface can result in a notable change of the contact angles(> 40°) on the surface. The finding provides new insights into the correlation between the molecular-scale interfacial water structures and the macroscopic wettability of the hydroxylated silica surface.     

Novel potential energy surface-based quantum dynamics of ion–molecule reaction O~++ D_2→OD~++ D

According to a novel electronic ground-state potential energy surface of H_2O~+(X~4 A~'),we calculate the reaction probabilities and the integral cross section for the titled reaction O+~+ D_2→OD~++ D by the Chebyshev wave packet propagation method.The reaction probabilities in a collision-energy range of 0.0 e V–1.0 e V show an oscillatory structure for the O~++ D_2 reaction due to the existence of the potential well.Compared with the results of Mart′?nez et al.,the present integral cross section is large,which is in line with experimental data.     

Giant Magnetoimpedance Effect in Surface Modified CoFeMoSiB Amorphous Ribbons

Thin magnetic Fe layers in thickness of 10-240 nm were deposited onto a wheel surface of CoFeMoSiB amorphous ribbons to check our concept of a new type of heterogeneous magnetoimpedance materials formed by two different magnetic parts. The presence of an additional iron layer modifies the magnetoimpedance response of the composite material and leads to increase of the magnetoimpedance ratio from 330 to 345% at a frequency of 3.5 MHz. Two possible mechanisms are discussed for explanation to the observed behaviour. Modification of the surface properties of the amorphous ribbons may have certain potential for technological applications.     

VIBRATION OF IMMERSED RECTANGULAR COMPOSITE PLATE EXERTED BY UNDERWATER SOUND

Based on the theory of elastisity,according to the principle of least elastic energy and variationalmethod,the position of neutral surface of the elastic composite plate system is determined.And then,the governing equation for the flexural vibration of composite plate system is derived.After intro-ducing the equivalent rigidity,Poisson's ratio and surface mass density,the governing equation andboundary conditions of this plate system may be deduced in the form similar to those of thin platewith same boundary conditions.The governing equation for bending motion of elastic-viscoelasticcomposite plate system is derived from the theory of viscoelasticity.Then,the effective damping con-stant of plate system may be calculated by dynamic constants of material of these plates.A generalsolution for the bending motion of plate system is given by the method of normal mode analysis andFourier analysis.As an example,a simply-supported rectangular composite plate system is concerned.The equivalent rigidity,Poisson's r     

Heterogeneous Nucleation and Solidification Prediction of Sn-5wt.%Pb Droplets

We develop a model for heterogeneous nucleation catalyzed by oxidation on the droplet surface and the internal nucleation similar to surface oxidation. The fraction covered by oxide on the surface of the droplet is calculated as a function of time and temperature based on the chemical reaction dynamic and transition state theory, which is a reasonable expression for the oxidation behaviour of Sn-5wt.%Pb droplets. The continuous-cooling-transformation curves were computed using the above experimental results under the heterogeneous surface nucleation and the internal nucleation of droplets. Also, we predict the solidification behaviour of the droplet in gas-atomized spraying process using this model. The same model can be applied to predict the nucleation behaviour for any type of cooling schedule.     

A Facile Synthesis of Silver-Coated Composite Particles by Swelling Surface Method

We report a facile and rapid method for fabrication of composite particles consisting of a polystyrene (PS) core and a uniform silver shell. The process involves the PS colloid surface swelling, the anchoring of silver ions and nanoparticles onto the surfaces, and the subsequent growth of metal seeds in a short period. The present approach has the advantages of simplicity and high efficiency. The TEM images show the morphology of the obtained PS core-silver shell particles, and their chemical composition and crystallinity are analysed by x-ray diffraction. To our knowledge, this is the first study based on swelling PS surface for synthesis of silver-coated PS particles and may be implemented for preparing other metal-coated PS particles.     

An angular cutoff composite model for investigation on electromagnetic scattering from two-dimensional rough sea surfaces

Based on the local configuration angle division to select the corresponding method for electromagnetic scattering calculation from rough sea surface,this paper presents an angular cutoff composite model:when the local scattered angle is in the specular region that is given by an approximately 20 degrees cone around the specular direction,the Kirchhoff approximation is applied to evaluate the specular reflection,which dominates the total scattering in this region;the small perturbation method is employed to handle the diffuse reflection which is predominant as the local scattered angle is situated out of the specular region.Numerical results are compared with those of experimental and theoretical models in several configurations as a function of incident angle,wind speed,wind direction.The comparison of numerical results of other experimental and theoretical models in several configurations shows that the new composite model is robust to give accurate numerical evaluations for the sea surface scattering.     

Electron Emission Suppression from Cathode Surfaces of a Rod-Pinch Diode

The theory and method of suppressing electron emission from cathode surfaces is introduced, including increasing the emission threshold, reducing the surface electric field and shielding the emitted electrons. The stainless steel-graphite and Teflon-graphite composite cathodes are designed to test the above methods for a rod-pinch diode. The experiments are performed on the inductive voltage adder, and the results indicate that the Teflon-graphite composite cathode is effective in suppressing electron emission from the specified cathode surface, while the stainless steel-graphite composite cathode fails. The reasons are analyzed theoretically.     

A New Method for Generating Hydrogen from Water

A new method for generating hydrogen by the reaction of Al powder with water using iodine as additive is developed. 12 can penetrate through the surface oxide layer on aluminium to form AlI3. High solubility of AlI3 in water is benefited to activate Al surface. It is found that the production of hydrogen becomes significant above 60℃ and obeys a logarithm rule. The pH value which is determined mainly by the kinetics of hydration spontaneously. varies from 5 to 3 then back to 4.5 during the reaction, reaction of AlI3 and the reaction of Al and HI produced     

Siliconization for Wall Conditioning and Its Effect on Plasma Performance in HL-2A Tokamak

1 Experiments HL-2A tokamak is characterized by a large closed divertor chamber. Before the experimental campaign 2005 the surface of the shielding plates for the MP1 and MP2 has been covered with 2-D carbon fibre composite （about 30% of the first wall）, which can protect the first wall, and effectively shield the splash of heavy metal impurity. The vacuum vessel can be baked up to 120 ℃for degassing and a glow discharge device is installed in the vessel for cleaning the inner surface. Hydrogen glow discharge cleaning （GDC） is applied to remove impurities from the wall, and helium glow discharge cleaning for removing residual hydrogen.     

Application of the method of equivalent edge currents to composite scattering from the cone-cylinder above a dielectric rough sea surface

Compared with scattering from a rough surface only, composite scattering from a target above a rough surface has become so practical that it is a subject of great interest. At present, this problem has been solved by some numerical methods which will produce an enormous calculation amount. In order to overcome this shortcoming, the reciprocity theorem (RT) and the method of equivalent edge currents (MEC) are used in this paper. Due to the advantage of RT, the difficulty in computing the secondary scattered fields is reduced. Simultaneously, MEC, a high-frequency method with edge diffraction considered, is used to calculate the scattered field from the cone-cylinder target with a high accuracy and efficiency. The backscattered field and the polarization currents of the rough sea surface are evaluated by the Kirchhoff approximation (KA) method and physical optics (PO) method, respectively. The effects of the backscattering radar cross section (RCS) and the Doppler spectrum on the size of the target and the windspeed of the sea surface for different incident angles are analysed in detail.     

Mechanism analysis of reaction S~+(~2D)+H_2(X~1Σ_g~+) → SH~+(X~3Σ~-) + H(~2S) based on the quantum state-to-state dynamics

We present a state-to-state dynamical calculation on the reaction S~++ H_2→ SH~+ +H based on an accurate ~X2 A~″ potential surface. Some reaction properties, such as reaction probability, integral cross sections, product distribution, etc.,are found to be those with characteristics of an indirect reaction. The oscillating structures appearing in reaction probability versus collision energy are considered to be the consequence of the deep potential well in the reaction. The comparison of the present total integral cross sections with the previous quasi-classical trajectory results shows that the quantum effect is more important at low collision energies. In addition, the quantum number inversion in the rotational distribution of the product is regarded as the result of the heavy–light–light mass combination, which is not effective for the vibrational excitation. For the collision energies considered, the product differential cross sections of the title reaction are mainly concentrated in the forward and backward regions, which suggests that there is a long-life intermediate complex in the reaction process.     

First Principles Study of Adsorption and Reaction of CO on SrTiO3 （100） Surface： the Role of Surface Oxygen Vacancies

The adsorption and reaction of CO on SrTiO3 （100） surface with and without surface oxygen vacancy are investigated by the first-principles calculation based on the density functional theory. The calculated results reveal that the oxygen vacancy site prefers to the activation of the C-O bond. The adsorption energies increase to 1.0855 and 0.3245eV for defect-CO and defect-OC orientations, respectively. Particularly the C-O bond is elongated by about 0.1285 ？ in the defect-OC orientation compared with that in the Ti-OC one without surface oxygen vacancies. There is predominantly a chemisorption mechanism between the CO molecule and the surface in the defect-CO orientation.     

Application of aluminum foil for “strain sensing” at fatigue damage evaluation of carbon fiber composite

Surface layer of a loaded solid is an individual structural level of deformation that was shown numerously within concept of physical mesomechanics.This gives rise to advance in its deformation development under loading as well as allows using this phenomenon to sense the strain induced structure changes.It is of specific importance for composite materials since they are highly heterogeneous while estimating their mechanical state is a topical applied problem.Fatigue tests of carbon fiber composite specimens were carried out for cyclic deformation estimation with the use of strain sensors made of thin(80μm)aluminum foil glued to the specimen’s surface.The surface images were captured by DSLR camera mounted onto an optical microscope.Strain relief to form during cyclic loading was numerically estimated using different parameters:dispersion,mean square error,universal image quality index,fractal dimension and energy of Fourier spectrum.The results are discussed in view of deformation mismatch in thin foil and bulk specimen and are offered to be applied for the development of Structural Health Monitoring(SHM)approach.     

铂纳米晶合成中二价前驱体的还原动力学研究

In this letter, we report a quantitative analysis of how a Pt(Ⅱ) precursor is reduced to atoms at different temperatures for the formation of Pt nanocrystals with different morphologies and sizes. Our results suggest that in the early stage of a synthesis, the Pt(Ⅱ) precursor is reduced to atoms exclusively in the solution phase, followed by homogeneous nucleation to generate nuclei and then seeds. At a relatively low reaction temperature such as 22℃, the growth of the seeds is dominated by autocatalytic surface reduction that involves the adsorption and then reduction of the Pt(Ⅱ) precursor on the surface of the just-formed seeds. This particular growth pathway results in relatively large assemblies of Pt nanocrystals. When the reaction temperature is increased to 100℃, the dominant reduction pathway will be switched from surface to solution phase, producing much smaller assemblies of Pt nanocrystals. Our results also demonstrate that a similar trend applies to the seed-mediated growth of Pt nanocrystals in the presence of Pd nanocubes.     

TiO_2/Ag composite nanowires for a recyclable surface enhanced Raman scattering substrate

Multifunctional TiO2/Ag composite nanowires are fabricated with a hydrothermal method by precipitating Ag nanoparticles （NPs） on the surfaces of TiO2 nanowires. This hierarchical one-dimensional （1D） nanostructure can be used as a surface enhanced Raman scattering （SERS） substrate with high sensitivity, for detecting the rhodamine 6G （R6G） in a wide range of low concentrations （from 1 × 10 6 M to 1 × 10-12 M）. In addition, the substrate can be self-cleaned under the irradiation of ultraviolet （UV） light due to the superior photocatalytic capacity of the TiO2/Ag composite nanostructure, making the recycled use of SERS substrates closer to reality. With both the evident SERS performance and high efficiency of photocatalytic capacity, such TiOz/Ag composite nanowires demonstrate considerable potential in the chemical sensing of organic pollutants.     

Investigation of composite electromagnetic scattering from ship-like target on the randomly rough sea surface using FDTD method

Composite electromagnetic scattering from a two-dimensional (2D) ship-like target on a one-dimensional sea surface is investigated by using the finite-difference time-domain (FDTD) method. A uniaxial perfectly matched layer is adopted for truncation of FDTD lattices. The FDTD updated equations can be used for the total computation domain by choosing the uniaxial parameters properly. To validate the proposed numerical technique, a 2D infinitely long cylinder over the sea surface is taken into account first. The variation of angular distribution of the scattering changing with incident angle is calculated. The results show good agreement with the conventional moment method. Finally, the influence of the incident angle, the polarization, and the size of the ship-like target on the composite scattering coefficient is discussed in detail.     

Quasi-classical trajectory study of H+LiH(v=0,1,2,j=0)→Li+H_2 reaction on a new global potential energy surface

Quasi-classical trajectory(QCT) calculations are reported for the H+LiH(v = 0–2, j = 0)→Li+H_2 reaction on a new ground electronic state global potential energy surface(PES) of the LiH_2 system. Reaction probability and integral cross sections(ICSs) are calculated for collision energies in the range of 0 eV–0.5 eV. Reasonable agreement is found in the comparison between present results and previous available theoretical results. We carried out statistical analyses with all the trajectories and found two main distinct reaction mechanisms in the collision process, in which the stripping mechanism(i.e., without roaming process) is dominated over the collision energy range. The polarization dependent differential cross sections(PDDCSs) indicate that forward scattering dominates the reaction due to the dominated mechanism. Furthermore,the reactant vibration leads to a reduction of the reactivity because of the barrierless and attractive features of PES and mass combination of the system.