Papers by Keyword: Ionic Exchange

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Abstract: The oligodynamic property is a lethal effect which some atoms exert over bacteria, fungi and other microorganisms. The oligodynamic property can be promoted by glass microparticles doped by zinc ionic specimens utilizing the ionic exchange processes. This study is aimed at modelling the behavior of adsorption mechanisms of the zinc ions on glass microparticles absorbent, with potential use as antimicrobial material. Aqueous solutions of zinc nitrate were used as the ionic supplying of zinc ions. The amount of zinc adsorbed on the glass was determined by spectroscopy of atomic absorption and with a mass balance analysis for each adsorption conditions. The experimental data were modeled by three Eq.s employed in adsorption kinetics studies: pseudo first order, pseudo second order and Elovich Eq.. The pseudo second order data model presented the better adjust condition. A sample of zinc glass microparticles, prepared at the finest conditions established by the kinetic model of pseudo second order, was submitted to microbiological analysis: agar diffusion test with Pseudomonas aeruginosa and Staphylococcus aureus and with Candida albicans. The glass doped with ionic zinc inhibited the growth of microorganisms in every conducted analysis.
556
Abstract: The need for sewage purification of machine-building production from copper compounds which possess toxic, allergic, cancerogenic, gonadotropny and embryotoxic action, has been justified. The methods of studying of component and mineralogical composition of wastes, which are used for purification of model mortars, have been given. Some methods of purification of mortars from copper ions have been considered. The need for the search of alternative methods of purification, taking into consideration the composition and properties of the purified environments, and also taking into account the possible reset of purified sewage into natural reservoirs, has been shown. It has been revealed, that application of calcium- containingwaste as reagent won't help to additional alkalization of natural reservoirs. Prospects of use of regional industrial wastes for extraction of copper ions out of model mortarshave been shown. The mechanism of purification of model drains from copper ions by a combined reagent has been described.
851
Abstract: The development of antimicrobial materials and its use have shown an effective way to reduce the risks posed to human life by fungi, bacteria and other pathogenic microorganisms. This work presents preliminary results about the development of powder biocidal vitreous, applying the ionic exchange process between the sodium ions, present in the glass matrix, and ionic oligodynamic species, present in the ionic exchange medium. The magnitude of the oligodynamic effect was modified with the use of different metal ions, providing significant difference in antimicrobial performance. Three samples were prepared incorporating different ionic metal in its glass matrix during the ionic exchange process, Ag+, Zn2+ and Cu2+. These precursors of cations were used: AgNO3 for the silver ions, ZnSO4 for the zinc ions and Cu (NO3)2 for the cooper ions. Samples were submitted to microbiological analysis – Agar Diffusion Test for Escherichia coli and Staphylococcus aureus bacterial species, and fungus species Candida albicans – and atomic absorption techniques. Results showed higher microbiological magnitude to the silver-glass, followed by the cooper-glass and zinc-glass.
963
Abstract: The micro-lens array for CCD systems can enhance the utilization efficiency of light energy, then improve its detection sensitivity. This paper firstly researches on the principle of micro-lens array for CCD integration, the lens changing refractive index theory and the mechanism of ionic exchange on glass materials. Then, with reasonable design of the mask and optimization the ionic exchange process parameters, the paper finally produces the Rectangular Plane Arched Shape (RPAS) micro-lens array on the plate glasswith the unit feature size being 22μm x 22μm. The results show that the RPAS micro-lens array’s fill factors could be achieved 93%, and the spectral sensitivity can be improved by 0.3 times. The mask plays a decisive role in micro-lens which is manufactured by ionic exchanged method. The reasonable selection of the mask parameter can eliminate the void that in the circular aperture planar micro-lens array, and enhance the fill factor; in the ionic exchange process, it is easy to obtain the large refractive index by using the ion-pair that have big differences. The ionic exchanged temperature below the glass softening temperature at about 20°C is appropriate.
174
Abstract: Ion specimens can be incorporated in glasses or natural clays by ionic exchange process with different concentrations dependent of matrix´s type and of the ionic exchange parameters. In particular, the incorporation of silver ions presents high interest by its biocidal properties. A compound contending ion silver specimens presents bactericidal and fungicidal properties with effect proportional to ion concentration. This work presents results about application of the atomic absorption technical to determine the silver ion concentration incorporated in a glass matrix by ionic exchange process. The ionic exchange experiments were realized with different AgNO3 concentration and constant temperature. After ionic exchange process, the glass samples were submitted to characterization by Energy Dispersive X-Ray Spectroscopy and Atomic Absorption Techniques. The comparative results between different techniques showed that atomic absorption technical is adequate to determine ion silver concentration incorporated in the glass matrix after ionic exchange process.
873
Abstract: This work presents preliminary results of powder glasses with bactericide effect obtained by ionic exchange between sodium ions, present in glass composition, and silver ions, present in the ionic exchange medium. The powder glass was submitted to ionic exchange in ionic medium containing different concentration of silver species. The results showed a bactericide effect dependence on AgNO3 concentration in the ionic medium. Agar Diffusion Test on Escherichia coli bacteria, EDS analyses was applied to the samples; the results showed there is a critical concentration of silver ions incorporated in the powder glass and a limit to bactericide effect. The tests and analyses reveled that 6 wt% of AgNO3 in ionic medium was the critical concentration.
849
Abstract: In this work we examine the effect of the ionic exchange in cell behaviour of two apatite substrates with the same chemical composition but different microstructures (Coarse and Fine) by culturing cells with their extracts. A higher decrease in Ca and a higher increase in P concentrations were detected in the culture medium extracts from the finer apatite substrate in accordance with its higher specific surface area. A decrease in cell proliferation was observed when cells were cultured with the Fine extract in comparison with cells in contact with the Coarse extract or the control group. Although the higher ionic exchange, this could not explain the drastic decrease in cell proliferation observed on Fine apatite substrates, so a strong interaction with the underlying microstructure that modulates cell behaviour is also present.
1051
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