Papers by Keyword: Zinc

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Authors: Simone Ribeiro, Suelen Cristina Sartoretto, Rodrigo Resende, Marcelo Uzeda, Adriana Terezinha Alves, Silvia Albuquerque Santos, Giovana Pesce, Alexandre Malta Rossi, J.M. Granjeiro, Fulvio Miguel, Mônica Diuana Calasans-Maia
Abstract: The hydroxyapatite (HA) is a biocompatible and bioactive biomaterial used as bone substitute, however, the high crystallinity of HA and consequently its low solubility may be a limitation for its clinical use. In order to improve the biosorption of HA, the partial substitutions in the chemical structure and doping with small amounts of impurities have been study. The objective of this study was to evaluate the biocompatibility of 3% Zinc-containing nanostructured carbonated hydroxyapatite (ZncHA) compared with the carbonated hydroxyapatite (cHA), both synthesized at 37°C and non-sintered, using as control the stoichiometric HA microspheres in subcutaneous of mice. The X-ray Diffraction (XRD) and Vibrational Spectroscopy in Infra Red Fourier Transform (FTIR) were used to characterize the biomaterials. In vivo test was performed in BALB/c mice by implanting of HA, cHA and ZncHA spheres in the subcutaneous tissue for 1, and 9 weeks (n=5). The negative control consisted in incision without material implantation (Sham group). The samples were histological processed to descriptive analysis of biological effect. The microscopic analysis showed a similar granulation reaction between groups at the first experimental period. In 9 weeks there was a time dependent biosorption of cHA compared with other groups. In conclusion, the biomaterials tested were biocompatible and cHA group showed a significant biosorption in comparison with HA and ZncHA groups. The doping of zinc did not influence the biocompatibility of biomaterial, however, change the biosorption response
Authors: Gigliola Lusvardi, Ginaluca Malavasi, Ledi Menabue, Maria Cristina Menziani
Abstract: This review presents a combined experimental-computational strategy for the development of potential bioactive zinc–containing silicate glasses and shows how sound relationships among the structural role of some key elements that appear to control bioactivity can by established and exploit for rational glass design.
Authors: N. Pistofidis, G. Vourlias, D. Chaliampalias, F. Stergioudis, Efstathios K. Polychroniadis
Abstract: In the present work the phases of the zinc coatings deposited with hot-dip galvanizing, pack cementation and wire flame spraying are examined with Scanning Electron Microscopy and Transmission Electron Microscopy. The different phases which are observed are identified with the combined results of electron and X-Ray diffraction. From the results it is concluded that pack cementation coatings are consisted by two different layers while hot dip galvanized coatings are composed by the same phases and additionally two extra phases of the Fe-Zn phase diagram. Flame sprayed coatings are composed by pure zinc, in the form of thin lamellae, together with nanocrystaline zinc oxide which is formed from the oxidation of liquid metallic droplets during the spray procedure.
Authors: Zalilah Murni Yunus, Norzila Othman, Rafidah Hamdan, Nurun Ruslan Najwa, Norfarihah Abu Kasin, Nur Solini Leman
Abstract: In this study, activated carbon (AC) was produced from honeydew rind, a low-cost agricultural by-product, by chemical activation using H2SO4 as an activator was used as an adsorbent for the removal of zinc ions from aqueous solutions. Preparation method on the effect of surface morphology at different carbonization temperatures 450°C, 470°C, 490°C and 510°C was studied. The AC was characterized using FEM-SEM, FTIR and TG. Batch adsorptions were carried out to optimize different variables such as zinc concentration, contact time, pH and biosorbent amount. The results from AAS analysis showed that the maximum adsorption of zinc onto honeydew rind AC was achieved at the conditions of pH 7.5, 1.5g biosorbent amount, 1000mg/L initial zn concentration and 45min contact time. The maximum metal uptake and maximum removal were 66.55mg/g and 99.79% respectively.
Authors: Michaela Kolnerová, Jiří Sobotka, Pavel Solfronk
Abstract: The paper deals with the monitoring of utility properties of new coating type on the basis of Zn/Mg (ZM). For the comparison there was used commonly used coating in the series production of car-body panels on the basis of zinc (Z100). Measured results markedly contribute to improve production systems of car-body adhesion bonding on the basic of performed evaluation of applied coatings types utility properties quality with regard to influence of temperature and corrosion environment. Testing was carry out by T-peel test acc. to ISO 11339 when such type of loading represents crucial bonding fracture type. Thus results reveal information about behavior of adhesive joints strength properties together with the type of fracture as a criterion for suitable application of new coatings types on the basis of Zn/Mg and their implementation into series production of automobiles.
Authors: Michaela Kolnerová, Jiří Sobotka, Pavel Solfronk, Lukáš Zuzánek
Abstract: The paper deals with the application possibilities of new coatings types on the basis of Zn/Mg and their utilization at car-body production Comparison is done by evaluation bonded joints strength acc. to ISO 11339 for commonly used zinc-coated sheet at production car-body stampings (HDG Z100) with layer of new type on the basis of zinc/magnesium (ZM). Such utilization of new materials also means necessity to carry out test of the individual bonded car-body parts utility properties, mainly at peel loading, in dependence on adhesive type simultaneously with regard to the lubricant which is used in the technological process drawing of stampings and temperature under which is joint loaded. To guarantee required joints quality is one of the crucial criterions for applications new types of coatings in mass production.
Authors: Toru Tonegawa, Toshiyuki Ikoma, Tomohiko Yoshioka, Kazuo Shinozaki, Nobutaka Hanagata, M. Tanaka
Abstract: Insulin delivery carriers using low crystalline porous zinc hydroxyapatite (ZnHAp) microparticles with different crystal sizes and novel formulation method of poly (lactic acid) (PLA) have been developed to achieve the sustained-release of insulin. The adsorption isotherm curves of insulin dissolved into acetic acid of pH4.5 onto ZnHAp nanocrystals show non-Langmuir type due to the dissolution of the ZnHAp microparticles; the adsorption amounts were increased with the increase of crystalline sizes. The PLA formulation, coating the outer layer of microparticles, showed the apparent reduction of initial burst for insulin. The amounts of initial release of insulin decreased with the increase of crystalline sizes of ZnHAp, which could be attributed to the different meso-porous structure depending on its crystal sizes.
Authors: Ming Yan Dang, Hong Min Guo, Yan Kun Tan
Abstract: Chitosan was crosslinked using epichlorohydrin as crosslinking agent to prepare crosslinked chitosan which was used as an adsorbent for the removal of Zn(II) from aqueous solutions. The adsorption prosperities of Zn(II) on crosslinked chitosan were studied, including the influence of pH value and the adsorption kinetics. The kinetics of adsorption was discussed using two kinetic models, the pseudo first-order and the pseudo second-order model. Results reveal that the crosslinked chitosan is suitable as adsorbent to remove Zn(II) from dilute solution. The rate parameters for the Zn(II) by crosslinked chitosan were also determined. It was shown that the adsorption kinetics of Zn(II) could be best described by the pseudo second-order model and the adsorption process may involve a physical adsorption.
Authors: Yan Zhou, Yuan Hao Fang, Gan Ning Zeng, Chong Ying Zheng, Ning Ai, Tie Gan Wang, Hai Jun Bao, Hong Yan Zhou
Abstract: The adsorption of Zn2+ from simulated seawater onto biomaterial derived from the macroalgae Sargassum horneri was investigated via batch experiments. The highest adsorption rate was 96.9%, which found in the lower Zn2+ concentration solution where pH was 8.0 and temperature was 15°C, and the maximum adsorption capacity of dead Sargassum horneri particle to Zn2+ could arrive to more than 0.20 mg.g-1. Sargassum horneri pretreated with CaCl2 can increase the adsorption rate. Infrared analysis results showed that carboxylic acid groups have an important contribution to Zn2+ adsorption. The adsorption equilibrium of Zn2+ could be represented by pseudo-second-order model and the capacity of dead alga for Zn2+ was approximately constant. Conclusions could be drawn that Sargassum horneri is a kind of efficient biosorbent for the treatment of waste waters containing heavy metals. It was because Zn2+ can easily be desorbed by competition between the hydrogen ions and metal ions on the cell surface binding sites, that hydrochloric acid was proved to have economic feasibility.
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