Papers by Keyword: Zinc

Abstract: Biodegradable Mg, Zn and Fe alloys are currently studied as prospective biomaterials for temporary medical implants like stents for repairing damaged blood vessels and devices (screws and plates) for fixing fractured bones. In the present paper, novel Mg-, Zn- and Fe-biodegradable alloys are proposed. Advantages and disadvantages of the three kinds of alloys are demonstrated regarding the mechanical performance, in vitro corrosion behavior and biocompatibility.

Abstract: Anodization is an electrochemical process that converts the metal surface into a decorative, durable, corrosion-resistant, anodic oxide coatings. The thickness of the resulting layer depends on the process parameters (voltage, current, type of electrolyte, concentration and temperature of the electrolyte). In this work, the preparation of zinc metallographic samples with anodic layer is described. Samples prepared by anodic oxidation on the zinc substrate are rather brittle and porous. During the mounting, cutting, grinding and polishing the layer can be deformed which can affect the layer thickness measurements. The problem is to determine the boundary between anodic layer and resin. The cross-sectional micrographs were observed by scanning electron microscopy with the aim to improve anodic layers thickness measurements by means of digital image analysis.

Abstract: In this work, Zn-1.5Mg-0.5Ca alloy was studied. The alloy composition was chosen according to the results of our previous work that was focused on the research of biodegradable materials. The mechanical properties of such cast alloy are similar to the characteristics of human bones. Moreover, Zn-1.5Mg alloy itself satisfies biocompatibility requirements. The main goal of this work was to improve the mechanical properties of this alloy. A small addition of calcium affected both the alloy microstructure and mechanical properties. Light microscope and scanning electron microscope were used for the analysis of microstructure. After calcium addition, secondary phases were visible in observed micrographs; their composition was verified by XRD. Mechanical properties (Vickers hardness, compressive and tensile tests) were studied and compared with the Zn-1.5Mg alloy prepared in our previous work. Based on presented results, Zn-1.5Mg-0.5Ca alloy is intended for use in medicine as a suitable material for temporary implants.

Abstract: Pb–free solders have been widely developed by materials researchers as mainly focused on the replacement for Sn–Pb eutectic solder. In this study, Sn–3.0Ag–0.5Cu, Sn–3.0Ag–0.5Cu–xSb and Sn–3.0Ag–0.5Cu–xZn solders (x = 1.0, 2.0 and 3.0 wt%) were prepared using melting method. The effect of Sb and Zn addition on microstructure and properties, such as tensile strength, microhardness and corrosion resistance of Sn–Ag–Cu solders was investigated. The microstructure analysis revealed that addition of Sb and Zn to the Sn–Ag–Cu solders obviously decreased phase fraction of the dendritic β–Sn phase and the finer eutectic phase was obtained, resulting in superior mechanical properties of the Sn–3.0Ag–0.5Cu–xSb and Sn–3.0Ag–0.5Cu–xZn solders compared to the Sn–3.0Ag–0.5Cu solder. The results of potentiodynamic polarization tests indicated that the corrosion potentials of the Sn–3.0Ag–0.5Cu–xSb solders continuously increased with increasing of Sb content. While Zn content had little effect on the corrosion potentials of the Sn–3.0Ag–0.5Cu–xZn solders.

Abstract: The knowledge on human tissue is very important to recognize desirable properties of biomaterials. Host cells, extracellular matrix, integrated vessels and interstitial fluids create a complex and dynamic system able to regenerate and respond to environmental stimuli. Myoglobin is a protein with most of α-helices on its secondary structure, and responsible for oxygen binding and release in muscles, by the heme group. This work investigates the Mb adsorption process onto zinc-hydroxyapatite (ZnHA) surface by spectroscopic studies. To do so, ZnHA (0.05 g) was incubated with 4mL of 2mg Mb/mL on phosphate buffer solution pH 6.0 for 24h at 37°C. The FTIR analyses of ZnHA powders before and after protein adsorption provided information concerning the protein content. UV-Vis spectrocopy in the reflectance mode suggested a mixture of MbO₂ and Met Mb on lyophilized solid Mb, and the prevalence of MetMb form when Mb was adsorbed on ZnHA sample. The decrease of UV-Vis secondary bands suggests interactions through the Mb heme group and the ZnHA surfaces. Circular Dichroism (CD) spectroscopy indicated the maintenance of the Mb α-helices secondary structure after the adsorption process on ZnHA powders.

Abstract: In this work, zinc-containing hydroxyapatite (ZnHA) and hydroxyapatite (HA) discs were coated with native bovine serum albumin (BSA) using 100 μg/ml BSA solution at 37°C. Changes on BSA secondary structure from α-helix to β-turn were detected by deconvolution analyses of FTIR amide I band. Fluorescence images of MC3T3-E1 osteoblast cultured on HA and ZnHA discs revealed cells with elongated morphology, typical of 2D experiments, after 24 hours. An intense cytoskeleton organization was observed on samples coated with BSA.

Abstract: In this work, gamma–MnO₂ nanostructure was used as a sorbent to remove Zn (II) ion from aqueous solution. The influence of pH, sorption time and Zn (II) ion initial concentration were examined. The results showed that equilibrium adsorption was obtained after 60 minutes with 240 rpm of shaking speed at pH = 4.0. The experimental data were analyzed using five non-linear isotherm models: Langmuir, Freundlich, Sips, Tempkin and Dubinin – Radushkevich. The adsorption capacity (qm) from the Langmuir isotherm model for Zn (II) is founded as 55.23 mg/g. The heat of sorption process and the mean free energy were estimated from Temkin and Dubinin – Redushkevich isotherm models to be less than 8 kj/mol which vividly proved that the adsorption experiment followed a physical process. Kinetic studies have shown that although the adsorption data partially followed pseudo-first-order and pseudo-second-order equation for different time, it was well expressed by pseudo-second-order model.

Abstract: Galvanizing as a process of zinc coating of base material is still the most widely used technology applied in surface treatment of materials which are supposed to meet the requirement of high corrosion resistance in various environments. This article presents the results of research aimed at determining the corrosive properties of galvanized sheets in selected environments – distilled water, NaCl and SARS (Simulated Acid Rain Solution) solution, using electrochemical potentiodynamic test and electrochemical impedance test (Electrochemical Impedance Spectroscopy – EIS).

Abstract: The present work has the purpose to study and to evaluate the corrosion resistance of zinc layers and phenol – formaldehyde resin/Zn composite layers obtained by electrodeposition. For the best results it was used different parameters for electrodeposition such as: current density between 3 – 5 A/dm², time for electrodeposition: 30 minutes and 60 minutes, stirring rate: 500 rpm and 800 rpm. Different sizes (mean diameter size between 0.1 – 5.0μm and 6.0 – 10.0μm) of dispersed phases were used with concentration into electrolyte solution from 10g/L to 25 g/L of polymer particles. The morphology of the layers was investigated by SEM – EDX methods. The surface morphology of composite layers was different as compared with pure zinc layers. By adding polymer particles into zinc electrolyte during electroplating a very good distribution of polymer on zinc layer surface was obtained. The electrochemical behavior of the composite layers in the corrosive environment was investigated by polarization potentiodynamic and electrochemical impedance spectroscopy methods. As electrochemical test solution 0.5M sodium chloride was used in a three electrode open cell.

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