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In this study, corn straw and modified corn straw impregnated with Potassium hydroxide（KOH）were used as raw materials to prepare biochar (BC) and modified biochar (K-BC). SEM, FTIR, EDS and other analytical methods were used to study the structure of BC and K-BC, and the equilibrium adsorption method was used to compare and study the characteristics of BC and K-BC adsorbing Pb. The results show that when the solution is weakly acidic (pH 5), Quasi-second-order kinetics can accurately describe the adsorption process of Pb (R2 > 0.9875); the Langmuir model fits well, indicating that Pb adsorption by biochar is mainly a single-layer adsorption; the results of thermodynamic tests ∆H˚ > 0, ∆S˚ > 0, ∆G˚ < 0 indicate that the adsorption of Pb by biochar is a spontaneous, endothermic, and disorderly increase process. Combining elemental analysis, specific surface area pore size determination, SEM, and EDS for the characterization of materials before and after adsorption, it can be seen that the difference between BC and K-BC adsorption of Pb comes from the difference between the specific surface areas, pore structures and aromatic structures of the materials, accompanied by the ion exchange effect. [ABSTRACT FROM AUTHOR]

Recrystallization and precipitation behaviors after cold rolling and aging are investigated for Cu-0.7Cr-0.13Zr alloy. The processed alloy was characterized using the measurement of Vickers hardness, scanning electron microscopy, and transmission electron microscopy. The resultant complex microstructures are interpreted in terms of the interactions between precipitation and recrystallization. Upon aging at 500 °C for 1 h, the 45% rolled alloy exhibits a retarded recrystallization process and therefore an efficient hardening response, which are attributed to the pinning effect of fine dispersed precipitates on the dislocation. When heavily deformed and aged at high temperature, the alloy shows an accelerated process of recrystallization, and precipitates are found to coarsen. [ABSTRACT FROM AUTHOR]

A finite element eigenfunction method (FEEM) is presented for elastic (SH) wave scattering by cylinders of arbitrary cross section. The problem has been analyzed by enclosing the scatterer within an imaginary circular cylinder. The scattered field outside the circular cylinder is expanded in the usual cylindrical harmonics. The nearfield solution inside the circular cylinder is also assumed to be expanded by a series of eigenfunctions. The eigenfunctions for the nearfield are generated through the standard finite element technique by imposing suitable conditions on the circle. Then both the coefficients of the scattered field and those of the nearfield are found by means of a least-square fit for the continuity conditions across the circle. The solution obtained thereby is considered complete in the sense that both the scattered and the nearfields are solved simultaneously. The validity of this method has been verified by comparing results with calculations from exact analysis and the T-matrix method for (a) centered circular cylinder, (b) off-centered circular cylinder, (c) elliptical cylinder, and (d) square cylinder. [ABSTRACT FROM AUTHOR]