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Removal of zinc ions as zinc chloride complexes from strongly acidic aqueous solutions by ionic exchange

100%
Gîlcă E., Măicăneanu A., Ilea P.
Open Chemistry
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2014
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vol. 12
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issue 8
821-828
EN
The aim of this study was to compare several anion exchangers and to investigate the capacity of Amberlite IRA410 to remove zinc as chloride [ZnCl3]− from hydrochloric solutions (1 M). Influence of the process parameters such as stirring rate, resin quantity and zinc initial concentration over the removal process, was considered. The highest experimental ionic exchange capacity between the considered anionic exchangers, in the same working conditions (500 rpm, 5 g resin and 500 mg L−1), was obtained for Amberlite IRA410, 8.34 mg g−1. With an increase of zinc ions concentration, ionic exchange capacity increased up to 19.31 mg g−1 (1100 mg L−1). The experimental data were analysed using Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherm models. The results were also analyzed using sorption kinetics models, pseudo-first-, pseudo-second-order, intra-particle and film diffusion models. From the Dubinin-Radushkevich and Temkin isotherm models the mean free energy and heat of sorption were calculated to be 7.45 kJ mol−1, respectively 1×10−4 kJ mol−1, which indicates that zinc sorption is characterized by a physisorption process. Kinetic studies showed that the adsorption followed a pseudo-second-order kinetic model.
2
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Concentrations of retinol, α-tocopherol, copper, zinc and iron in plasma of young subjects differing in their engagement in motor activities

100%
Malara M., Hübner-Woźniak E., Kurczyńska A.
Biomedical Human Kinetics
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2012
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vol. 4
1-5
EN
Study aim: To assess possible effects of gender and of the level of motor activity on the deficiencies of selected vitamins and minerals in young subjects.Material and methods: Four groups of physical education (PE) students (n = 15 each) were studied: sedentary men (SM) and women (SF), and physically active men (AM) and women (AF) engaged in endurance sports, all aged 18 - 24 years, were studied. Somatic measurements included body height and mass, and body fat content (by Durnin's method, from 4 skinfolds), the biochemical ones included concentrations of retinol, α-tocopherol, copper, zinc and iron in plasma.Results: Men had significantly higher retinol (p<0.05) and iron (p<0.01) levels than women. The AM and SF groups had significantly (p<0.05 - 0.01) higher plasma levels of copper and zinc than Group SM. Group AF had lower zinc levels than Groups AM and SF, that latter group having lower α-tocopherol compared with Group SM.Conclusions: Inasmuch the observed differences could be due to the respective intakes, the effect of motor activity and the associated increased elimination of minerals could not be ruled out.
3
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Trace metals analysis of soil and edible plant leaves from abandoned municipal waste dumpsite in Owerri, Imo state, Nigeria

100%
Ibe F. C., Beniah O. I., Enyoh C. E.
World News of Natural Sciences
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2017
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vol. 13
27-42
EN
Municipal refuse may increase heavy metal concentration in soil, even at low levels, and their resulting long-term cumulative health effects are among the leading health concerns all over the world. In this study, we investigated the concentration of heavy metals in soils and edible plant leaves grown in an abandoned dumpsite along Akachi road in Owerri municipality. The soil samples were collected at each plot using a soil auger at the depth of 0-10 cm. Leaves of dominant edible plant species were selected and collected from each sample plot. The samples were dried in an oven with forced air at 40 °C, milled to fine powder then digested with 10 ml concentrated HNO3 and 5 ml concentrated HClO4 and were analyzed for Cr, Cu, Fe, Mn, Al, and Zn, using an H183200 MultiParameter Bench Photometer. Result showed that metals in in the sampled soils included (in order of quantity) Cr: 150-280 >Fe: 116.50-203 >Cu: 12.4-18.8 >Mn: 0-20 >Al: 0.08-0.16 >Zn: 0-1.4 mg kg-1 Dw. Moreover, levels of metals in the edible plant leaves are in the order of: Zn>Fe>Cu>Al>Mn>Cr. Zn, in particular, was higher than FAO/WHO recommended limits. Still, application of Pollution Load Index and Ecological risk models showed that the area is unpolluted and safe for use. Daily Metal Intake estimates indicated that zinc is mostly consumed from the plant species. The trends in Transfer Factor for the heavy metal in vegetable samples studied were in order: Zn>Al>Cu>Mn>Fe>Cr. Therefore, abandoned solid waste dumpsites contained significant concentrations of heavy metals which are later absorbed and accumulated by plants growing it.
4
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Optimization of corrosion inhibition of Picralima nitida leaves extract as green corrosion inhibitor for zinc in 1.0 M HCl

100%
Ezeugo J. N. O., Onukwuli O. D., Omotioma M.
World News of Natural Sciences
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2017
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vol. 15
139-161
EN
Herein, the optimization of inhibitive action of the ethanol extract of oil from Picralima nitida leaves, towards acid corrosion of zinc, was tested using weight loss and thermometry methods. We found that the extract acts as a good corrosion inhibitor for zinc corrosion in 0.1 M HCl solutions. The inhibition action of the extract was discussed in view of Langmuir adsorption isotherm. This revealed that spontaneous processes govern the adsorption of the extract on zinc surface. Herein, the inhibition efficiency (IE) increases in line with corresponding increase in extract concentration. The temperature effect of the corrosion inhibition on the IE was also studied. This indicated that the presence of the extract increases the needed activation energy of the corrosion reaction. Furthermore, in our work, an optimal inhibition efficiency IE (%) of 86.78 was obtained at optimum inhibitor concentration of 1.2 gl-1, optimum temperature and time of 313 k and 8 hrs, respectively. From the calculated thermodynamic parameters, it can be said, then, that Picralima nitida extract provides good protection to zinc against pitting corrosion in chloride ion containing solutions.
5
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Zinc-containing bioactive glasses for bone regeneration, dental and orthopedic applications

100%
Balasubramanian P., Strobel L. A., Kneser U., Boccaccini A. R.
Biomedical glasses
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2015
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vol. 1
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issue 1
EN
Zinc is a vital and beneficial trace element found in the human body. Though found in small proportions, zinc performs a variety of functions in relation to the immune system, cell division, fertility and the body growth and maintenance. In particular, zinc is proven to be a necessary element for the formation, mineralization, development and maintenance of healthy bones. Considering this attractive attributes of zinc, recent research has widely focused on using zinc along with silicate-based bioactive glasses for bone tissue engineering applications. This paper reviews relevant literature discussing the significance of zinc in the human body, along with its ability to enhance antibacterial effects, bioactivity and distinct physical, structural and mechanical properties of bioactive glasses. In this context, even if the present analysis is not meant to be exhaustive and only representative studies are discussed, literature results confirm that it is essential to understand the properties of zinc-containing bioactive glasses with respect to their in vitro biological behavior, possible cytotoxic effects and degradation characteristics to be able to effectively apply these glasses in bone regeneration strategies. Topics attracting increasing research efforts in this field are elaborated in detail in this review, including a summary of the structural, physical, biological and mechanical properties of zinc-containing bioactive glasses. This paper also presents an overview of the various applications in which zinc-containing bioactive glasses are considered for use as bone tissue scaffolds, bone filling granules, bioactive coatings and bone cements, and advances and remaining challenges are highlighted.
6
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Characterization of Ca50Mg20Zn12Cu18 Alloy

72%
Hrapkowicz B., Lesz S. T.
Archives of Foundry Engineering
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2019
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vol. 19
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issue 1
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