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Search Results: 1 - 10 of 1673 matches for " Zn "
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Electrochemical Behavior and Corrosion Study of Electrodeposits of Zn and Zn-Fe-Co on Steel  [PDF]
Concei??o A. M. Dutra, Eduardo N. Codaro, Roberto Z. Nakazato
Materials Sciences and Applications (MSA) , 2012, DOI: 10.4236/msa.2012.36050
Abstract: From industrialized baths, free of cyanide, the corrosion behavior of electrodeposits of zinc and zinc alloys was studied by means of electrochemical tests in aerated solution of 3.5% (0.6 M) NaCl at pH 8.2. In literature, several studies are found about zinc coatings and zinc alloys, for example, Zn-Ni and Zn-Co, nevertheless there is little about the ternary alloy Zn-Fe-Co. The Fe presence in the alloy results in a good adhesion to the substrate and allows application of these materials at higher temperatures. The electrochemical tests were carried out by obtaining open circuit potential curves with immersion time, potentiodynamic polarization curves and cyclic voltammetry. From the obtained results, the large potential differences observed between the steel and the electrodeposits showed that the last protect the substrate, acting as a sacrifice metal. The tests disclosed similar behaviors in both the current densities and the corrosion potential for electrodeposits of Zn and Zn-Fe-Co. After chromate passivation process, a significant decrease in corrosion density was noted for Zn and when the system was de-aerated there was change in the cathodic process mechanism.
Corrosion Resistance of Zn and Zn-Ni Electrodeposits: Morphological Characterization and Phases Identification  [PDF]
Concei??o A. M. Dutra, José W. J. Silva, Roberto Z. Nakazato
Materials Sciences and Applications (MSA) , 2013, DOI: 10.4236/msa.2013.410079
Abstract:

Zinc alloys coatings formed with elements of group VIIIB are promising because they display similar properties and protect steel by galvanic action. The Zn-Ni alloy is remarkable by showing improved mechanical properties and better corrosion resistance when compared to zinc coatings of similar thickness, also can be applied at higher temperatures. In this work, electrodeposits of Zn, Zn-12%Ni, obtained upon SAE 1010 steel from commercial alkali baths, were treated by blue chromatization and characterized according to mechanical properties and morphology. Studies were carried out by using measures of hardness, roughness, SEM, EDS and XRD. Among the studied electrodeposits, alloys treated by chromatization showed higher corrosion resistance and Zn-Ni electrodeposits showed higher value of roughness and hardness, while zinc coating had results similar to the steel substrate By means of XRD, it was found that electrodeposits are crystalline, being identified in Zn-Ni alloy the presence of the phases g(Ni5Zn21) and d(Ni3Zn22), which are responsible for its higher corrosion resistance.

Elements Content in Otolith as Pollution Indicator for Cultured Sea Bass (Lates calcarifer) of Malaysia  [PDF]
Afiza Suriani Sarimin, Che Abd R. Mohamed
Journal of Environmental Protection (JEP) , 2012, DOI: 10.4236/jep.2012.312184
Abstract:

Otoliths of cultured sea bass and ambient waters were sampled from 24 fish cages and ponds in Malaysia to investigate the contents of Sr, Mg, Ba, Cd and Zn. The following elements content in otolith and water were analysed with Inductively Coupled Plasma Mass Spectrometer (ICP-MS) and/or Atomic Absorption Spectrometer (AAS) to determine the anthropogenic impacts based on the grouping characterisation of the sampling locations. Three groups i.e. A, B and C were characterised according to the least, intermediate and high anthropogenic impact to otolith elemental content. The Enrichment Factor (EF) and Metal Pollution Index (MPI) were calculated to determine the pollution source and level. The content of Ba in otolith was found positively related with the salinity variation and Ba content in water. Elevated content of Zn in otolith and water was found in group A suggesting that oil leaking from tourist boating activities effects exceed the urbanisation and industrialisation impact. EFznsupport the enrichment of Zn in waters which exceed the recommended level. MPI showed that group A > C > B and support that tourism activities affect the pollution level and indicate otolith functioned as pollution indicator. Highest EFcdsuggested Cd incorporation onto otolith despite of the low content of Cd in water. The sequence of the elements content in otolith and water are Sr > Mg > Zn > Ba > Cd and Sr > Mg > Ba > Zn > Cd respectively.

The Factors on Removal of Zinc Cation from Aqueous Solution by Bentonite  [PDF]
Shuli Ding, Juanjuan Shen, Bohui Xu, Qinfu Liu, Yuzhuang Sun
Natural Resources (NR) , 2011, DOI: 10.4236/nr.2011.22015
Abstract: The removing zinc cation from aqueous solution by Ca-bentonite and Na-exchanged bentonite was studied. The factors such as the initial concentration of Zn2+, the liquid-to-solid ratio, pH, adsorption time, stirring speed, coexisting ions, temperature and bentonite particle size were investigated. The results show that the adsorption process of bentonite accorded with the Freundlich isotherm model, the removal of Zn2+ by Ca-bentonite and Na-exchanged bentonite reached equilibrium in 2 h, and adsorption of Na- bentonite was superior to Ca-bentonite. The adsorption rate of zinc increased with increasing pH, temperature, stirring speed, time span and with decreasing bentonite particle, the initial concentration of Zn2+ and the liquid-to-solid ratio. In mixed solution which contains Pb2+and Cr6+, Pb2+ has no influ- ence on the removal of Zn2+ by both the bentonites while Cr6+can decease it.
Synthesis, Morphology and Magnetic Characterization of Zn Ferrite Powders  [PDF]
S. A. Popescu, P. Vlazan, P. V. Notingher, S. Novaconi, I. Grozescu, A. Bucur, P. Sfirloaga
Journal of Electromagnetic Analysis and Applications (JEMAA) , 2010, DOI: 10.4236/jemaa.2010.210078
Abstract: We synthesized Zn0.8Fe2.2O4 ferrite powders by coprecipitation and hydrothermal techniques and analyzed the mor-phology and magnetic properties. The morphology and structure of the Zn ferrite powders were investigated using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD) identifying the crystallization planes. Magnetic hysteresis curves were obtained for the Zn ferrites samples.
Structural Stabilizing Effect of Zn Substitution on MnAl and Its Magnetic Properties  [PDF]
H. X. Wang, P. Z. Si, W. Jiang, J. G. Lee, C. J. Choi, J. J. Liu, Q. Wu, M. Zhong, H. L. Ge
Open Journal of Microphysics (OJM) , 2011, DOI: 10.4236/ojm.2011.12003
Abstract: The effect of Zn substitution on the structure and magnetic properties of τ-MnAl has been investigated sys-tematically. It is found that Zn substitution can stabilize the structure of τ-phase and thus a significant amount of τ-phase can be produced. Zn increases the coercivity and saturation magnetization of the τ-MnAl but reduces the Currie temperature. However, excess Zn is detrimental to the magnetic parameters. The optimum magnetic performance was found in samples with Zn substitution to 2.9% Mn atoms and 3.5% Al atoms, respectively.
The Effect of Zn Concentration on the Optical Properties of Cd10–xZnxS Films for Solar Cells Applications  [PDF]
Nathera A. Al-Tememee, Nada M. Saeed, Sundus M. A. Al-Dujayli, Baha T. Chiad
Advances in Materials Physics and Chemistry (AMPC) , 2012, DOI: 10.4236/ampc.2012.22012
Abstract: In this paper, Cd10–xZnxS (x = 0.1, 0.3, 0.5) films were deposited by using chemical spray pyrolysis technique, the molar concentration precursor solution was 0.15 M/L. Depositions were done at 350?C on cleaned glass substrates. X-ray diffraction technique (XRD) studies for all the prepared film; all the films are crystalline with hexagonal structure .The optical properties of the prepared films were studied using measurements from VIS-UV-IR spectrophotometer at wave-length with the range 300 - 900 nm; the average transmission of the minimum doping ratio (Zn at 0.1%) was about 55% in the VIS region, it was decrease at the increasing of Zn concentration in the CdS films, The band gap of the doped CdS films was varied as 3.7, 3.8, 3.6 eV at x = 0.1, 0.3 and 0.5 respectively.
Removal of Zn (II) from Aqueous Solution onto Kaolin by Batch Design  [PDF]
Bahia Meroufel, Omar Benali, Mohamed Benyahia, Mohamed Amine Zenasni, André Merlin, Béatrice George
Journal of Water Resource and Protection (JWARP) , 2013, DOI: 10.4236/jwarp.2013.57067
Abstract:

The Algerian kaolin clay was investigated to remove Zn(II) heavy metal ion from aqueous solution. The effect of contact time, initial metal ion concentration, pH and temperature was experimentally studied in batch mode to evaluate the adsorption capacity, kinetic, thermodynamic and equilibrium. The extent of zinc adsorption increased with increasing initial concentration of adsorbat, pH and temperature. The linear Langmuir and Freundlich models were applied to describe equilibrium isotherms and both models fitted well. The monolayer adsorption capacity for Zn(II) ions was 12.23 mg per g of kaolin clay at pH 6.1 and 25°C. Dubinin-Radushkevich (D-R) isotherm model was also applied to the equilibrium data. Thermodynamic parameters showed that the adsorption of Zn(II) onto kaolin clay was spontaneous and endothermic process in nature. Furthermore, the Lagergren-first-order and pseudo-second-order models were used to describe the kinetic data. The experimental data fitted well the pseudo-second-order kinetic. As a result, the kaolin clay may be used for removal of zinc from aqueous media.

Molecular Basis of Hypertension: A Systematic Review on the Role of Metal Ions for Increase Prevalence of Hypertension in India  [PDF]
Kshetrimayum Birla Singh
Journal of Biosciences and Medicines (JBM) , 2016, DOI: 10.4236/jbm.2016.47002
Abstract: Metal ions played critical role in regulation of hypertension (HT) or blood pressure (BP). The physiological roles of metals commonly present in the diet in the etiology of HT need to be reviewed as recent survey on the metal status in the various vegetable and meat food stuffs commonly consumed by living population in India revealed an imbalance in its level. Higher levels of zinc (Zn) in diet is observed to increase the BP by various mechanisms including oxidative stress through decreased activity of superoxide dismutase (SOD) enzyme, increasing levels of angiotensin converting enzyme (ACE) and aldosterone and by causing acidification due to change in the levels of H+, Na+, K+ and Ca2+ ions in the blood. High level of copper (Cu) and low level of magnesium (Mg) and manganese (Mn) in the blood is also associated with HT through various mechanisms like elevation of chronic inflammation, accelerating Na+ pump of cell membrane and by disturbing lipid metabolism in the body. An epidemiological study conducted in the population of Manipur, India consuming Zn rich diet reveals significant disparities in distribution of the metals in the blood of the hypertensive (HTS) patients as compared to the normotensives (NT) control and thus indicates that the change in body metal homeostasis may be a triggering factor for the development of HT in this population and corroborate the reports of published literatures. The role of the metals variations in the body and their possible involvement in HT is reviewed and discussed in this paper.
Effect of Zn Substitution on the Magnetic and Magnetocapacitance Properties of Nanosized Multiferroic GaFeO3 Ceramics  [PDF]
Tai-Chun Han, Chun Yen, Yi-De Chung, Meng-Lin Wu
New Journal of Glass and Ceramics (NJGC) , 2018, DOI: 10.4236/njgc.2018.84005
Abstract: This article aims to investigate the possibility to turn the multiferroic orders and magnetocapacitance effect close to/above room temperature in nanosized GaFeO3 ceramics by a sol-gel preparation method and substitution with non-magnetic Zn atoms. Therefore, in this work, we have synthesized a series of nanocrystalline Ga1-xZnxFeO3(GZFO, x = 0, 0.01, 0.05 and 0.1) ceramic samples and study the effect of Zn substitution on their structural, magnetic, and electric properties. All the GZFO samples have an orthorhombic structure with Pc21n space group and the value of lattice parameters increase systematically with increasing Zn concentration. Interestingly, it shows that magnetic and electric properties are strongly dependent on the Zn substitution concentration. Based on the results of temperature-dependent magnetizations, M(T), it is observed that with increasing Zn-content up to 0.10, the ferrimagnetic transition temperature (TC) increases from 306 to 320 K. It is also found that the nanocrystalline Zn-doped GaFeO3 (GFO) samples exhibit the characteristics of ferroelectricity at room temperature. Furthermore, the?magnetization, ferroelectric polarization
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