Increasing the adsorption capabilitiy of mordenite and Y zeolites via post‐synthesis chemical/physical treatments in order to remove cationic dyes from polluted water

Different post‐synthesis approaches were used to increase the adsorption abilities of zeolite mordenite and Y in removal of cationic dye molecules as typical dyestuff pollutants. Various methods including acid leaching, alkaline treatment, dealumination with hexafluorosilicate, sonication and combination of them were employed to alter the porous structure of various types of selected zeolites. The dealumination (due to acid leaching), desilication (due to alkaline treatment) and disintegration (due to shear forces generated by ultrasound waves) were responsible for the alteration of pores size and accessibility in mordenite. Acid leaching combined with irradiation of ultrasound was found to be most effective technique in adsorption of rhodamine B as a large dye molecule into mordenite. In the case of zeolite Y, a chemical treatment with ammonium hexafluorosilicate resulted in considerable improvement of adsorption of rhodamine B.     

Micromechanical analysis of second order work in granular media

This paper examines instabilities in granular materials from a microscopic point of view through numerical simulations conducted using a discrete element method on two three-dimensional specimens. The detection and the tracking of grain scale deformation mechanisms constitute the key point for a better understanding the failure process and puzzling out what lies behind the vanishing of the macroscopic second order work. For this purpose, the second order work from microscopic variables, involving contact force and branch vector, was introduced and tracked numerically. Then, all contacts depicting negative values of the second order work were deeply investigated, especially their spatial distribution (homogeneity, agglomeration, dispersion $\ldots $ ) within the specimen according to the density of the granular assembly and to the loading direction. A set of comparisons has been considered in this context in order to highlight how a specimen is populated with such contacts whether it is loaded along a direction included within the plastic tensorial zone or along a direction for which the specimen is likely to behave elastically (elastic tensorial zone). Moreover, these comparisons concerned also loading directions within the cone of instability so that links between the vanishing of both microscopic and macroscopic second order works can be established and the local mechanisms responsible for failure occurrence may be figured out.     

The Effect of Multiple Surface Treatments on Biological Properties of Ti-6Al-4V Alloy

In this research, the effect of various surface treatments including laser processing, grit blasting and anodizing on chemical structure, surface topography, and bioactivity of Ti-6Al-4V was investigated. Six groups of samples were prepared by a combination of two alternative laser processes, grit blasting and anodizing. Selected samples were first evaluated using microanalysis techniques and contact roughness testing and were then exposed to in vitro environment. Scanning electron microscopy was used to characterize the corresponding final surface morphologies. Weight measurement and atomic absorption tests were employed for determination of bioactivity limits of different surface conditions. Based on the data obtained in this study, low-energy laser processing generally yields a better biological response. The maximum bioactivity was attained in those samples exposed to a three step treatment including low-energy laser treatment followed by grit blasting and anodizing.