Bloch定理与散射平面波的干涉

从波动学的角度分析空晶格模型中的自由电子在周期性晶体势微扰作用下转变为晶体中Bloch电子的过程,揭示出了这一过程的物理实质,结果表明,在晶体势微扰作用下,代表空晶格模型中自由电子定态波函数的行进平面波在晶体内各点处产生了各种许可波矢的散射平面波,Bloch定理是晶体微观结构的平移对称性（即周期性）使得这些散射平面波产生干涉的结果。     

On the local nature of the strain field calculation method for measuring heterogeneous deformation of cellular materials

A strain field calculation method based on the optimal local deformation gradient technique has been developed to calculate the ‘local’ strain tensor of cellular materials using cell-based finite element models. The local nature and accuracy of this method may be strongly dependent on the cut-off radius, which is introduced to collect the effective nodes for determining the optimal local deformation gradient of a node. Two different schemes are first analyzed to determine the suitable cut-off radius by characterizing the heterogeneous deformation of Voronoi honeycombs under uniaxial compression and we suggest that in Scheme 1, the cut-off radius defined based on the reference configuration is about 1.5 times the average cell radius; in Scheme 2, the cut-off radius defined based on the current configuration is about 0.5 times the average cell radius. Then, Scheme 3, a combined scheme of the two former schemes, is further suggested. It is demonstrated that the optimal cut-off radius in Scheme 3 characterizes the local strain reasonable well whether the compression rate is low or high. Finally, the strain field calculation method with the optimal cut-off radius is applied to reveal the evolution of the heterogeneous deformation of two different configurations of double-layer cellular cladding under a linear decaying blast load. The 2D fields and the 1D distributions of local engineering strain are calculated. These results interpret the shock wave propagation mechanisms in both claddings and provide useful understanding in the design of a double-layer cellular cladding.     

Study on Complex of Re(III) with 3, 5-Br2-DMPAP by Electrochemistry and Application

ABSTRACT

The electrochemical character of a new reagent, 2-(3, 5-Dibrome-2-pyriclyiazo)-5-dimethylaminophenol(3, 5-Br₂-DMPAP) was studied in HAc-NaAc medium at pH=3.50. In single sweep polarography, the reduction potential of the complex wave (-1.05V) is more negative than that of the free ligand(-1.01V). The complex wave was proven to be an adsorption wave. The composition ratio of the complex was formed to be 1:1 using a molar ratio method. The current of the adsorptive peak at-1.05V was directly proportional to the concentration of Re(III) in the range of 1.5× 10^?8～7.0×10^?5mol/l. The microamount of Re in several samples of Chinese cigarettes determined with satisfactory accuracy and precision.     

Determination of Riboflavin Using the Polarographic Reduction Wave of Its Photochemical Reaction Products

Abstract

A new, simple, and sensitive method for the determination of riboflavin based on the single-sweep polarographic reduction wave of the photolysis products of riboflavin has been developed. Under the irradiation of an iodine-tungsten lamp, the photolysis reaction of riboflavin in pH 9.3 NH₃-NH₄Cl buffer solution can be complete in about 20 min. The reaction products yield a single adsorptive reduction wave at ?0.63 V (vs. SCE) negative to the reduction wave of riboflavin by 0.18 V. The derivative wave height is linearly proportional to the concentration of riboflavin in the range of 0.01–17.5 µg/mL (correlation coefficient 0.996). The detection limit is 0.00 5µg/mL. The proposed method has been applied to the determination of multivitamin tablets with satisfactory results. In comparison with the methods directly using the reduction wave of riboflavin for the determination, this method eliminates the effect of the degradation of riboflavin on the determination accuracy and is much more sensitive. The new method could be useful in many fields.     

Detection of Multiple Herbicide Residues Using A Planar Array Evanescent Field Immunosensor

ABSTRACT

A planar array evanescent immunosensor, equipped with a charge-coupled device (CCD) as a detector was used to simultaneously detect pesticides, paraoxon, carbofuran and tetrachloroethylene. Wells approximately 2.5 mm in diameter were formed on glass slides using a photoactivated optical adhesive. Coating haptens were covalently attached to the bottoms of the circular wells to form a sensing surface. The detection of the hapten was completed through competitive immuno-reaction between the coasting haptens, and haptens in solution, with the corresponding antibody in solution. The identification and amount of antibody bound at each location on the slide were determined by quantitative image analysis. Concentrations as low as 0.5ng/mL of paraoxon, 0.Ing/mL of carbofuran, and 0.2ng/mL of tetrachloroethlene could be measured.     

Cyclic Square Wave Voltammetry: Theory and Experimental

Abstract

The voltage wave form of cyclic square wave voltammetry (CSWV) and its theory are presented, and experimental verification of theoretical work for CSWV is given. Indications are that the peak potential difference, E_p, of the differential current between the forward sweep and the reverse sweep is zero. Their peak heights have the same value for a reversible electrode reaction, zero, a different value for a reversible electrode reaction with stripping process, not zero, and the same value for a quasi-reversible electrode reaction. According to this property, the reversibility of an electrode reaction can be easily determined.     

Investigations on the formation of tracks in crystals

The minimal energy loss (dE/d ζ)_k [MeV cm²/mg] for the formation of a track in an insulator has been determined for mica, tourmaline, quartz glass, quartz crystal, lithium niobate and beryl. The investigations show that the (dE/d ζ)_k value of a track detector can be roughly estimated from the thermal conductivity of the given material.     

Some extensions on the soliton solutions for the Novikov equation with cubic nonlinearity

In this paper, by using the bifurcation method of dynamical systems, we derive the traveling wave solutions of the nonlinear equation UU_τyy ? U_yU_τy + U²U_τ + 3U_y = 0. Based on the relationship of the solutions between the Novikov equation and the nonlinear equation, we present the parametric representations of the smooth and nonsmooth soliton solutions for the Novikov equation with cubic nonlinearity. These solutions contain peaked soliton, smooth soliton, W-shaped soliton and periodic solutions. Our work extends some previous results.