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Electrochemical Characteristics of Natural Mineral Covellite

Open Journal of Metal 2012年第3期2卷 60-67页

作者： Mirjana Rajcic-Vujasinovic zoran stevic Sanja Bugarinovic Technical Faculty in Bor University of BelgradeBorSerbia Mining and Metallurgy Institute Zeleni BulevarBorSerbia

Electrochemical characteristics of covellite (CuS) are of importance from flotation and metallurgical point of view, as well as due to its potential application in solid state solar cells and in photocatalytic reactions. Also, the compound CuS appears as an intermediary product or a final product in electrochemical oxidation reactions of chalcocite (Cu2S) which exhibits supercapacitor characteristics. Natural copper mineral covellite has been investigated in inorganic sulfate acid electrolytes, as well as in strong alkaline electrolyte. Physical properties of covellite were characterized by X-ray diffraction (XRD) and the active surface was examined by optical and electron microscopy (EM) before and after oxidation in galvanostatic regime. Different electrochemical methods (galvanostatic, potentiostatic, cyclic voltammetry and electrochemical impedance spectroscopy - EIS) have been used. The capacitance of around 21 Fcm-2 (geometric area), serial resistance of about 90 Ωcm2 and leakage resistance of about 1200 Ωcm2 have been measured in 1 M H2SO4. The addition of cupric ions in sulfate electrolyte leads to the significant increasing of the capacitance, but having the increase of self-discharge as a negative side phenomenon. The capacitance of around 6.7 Fcm-2 (geometric area), serial resistance of about 80 Ωcm2 and leakage resistance of about 380 Ωcm2 have been measured in 6 M KOH.

关键词： Covellite Capacitance Copper Sulfides Electrochemical Characterization Solar Cells

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Identification and characterization of single crystal Bi_(2)Te_(3-x)Se_(x) alloy

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Transactions of Nonferrous Metals Society of China 2015年第10期25卷 3279-3285页

作者： Emina POZEGA Svetlana IVANOV zoran stevic Ljiljana KARANOVIC Rudolf TOMANEC Lidija GOMIDZELOVIC Ana KOSTOV Mining and Metallurgy Institute Bor Technical Faculty Bor University of Belgrade Faculty of Mining and Geology University of Belgrade

The results of experimental investigation of n-type semiconductor based on Bi2Te3 alloy were presented. This material is used in manufacture of thermoelectric coolers and electrical power generation devices. BizTe2.88Se0.12 solid solution single crystal has been grown using the Czochralski method. Monitoring of structure changes of the sample was carried out by electron microscope. The elemental composition of the studied alloy was obtained by energy dispersive spectrometry （EDS） analysis and empirical formula of the compound was established. X-ray diffraction analysis confirmed that the Bi2Te2.88Se0.12 sample was a single phase with rhombohedral structure. The behavior upon heating was studied using differential thermal analysis （DTA） technique. Changes in physical and chemical properties of materials were measured as a function of increasing temperature by thermogravimetric analysis （TGA）. The lattice parameters values obtained by X-ray powder diffraction analyses of Bi2Te2.88Se0.12 are very similar to BizTe3 lattice constants, indicating that a small portion of tellurium is replaced with selenium. The obtained values for specific electrical and thermal conductivities are in correlation with available literature data. The Vickers microhardness values are in range between HV 187 and HV 39.02 and decrease with load increasing. It is shown that very complex process of infrared thermography can be applied for characterization of thermoelectric elements and modules.

关键词： Bi_(2)Te_(3) Bi_(2)Te_(3-x)Se_(x) single crystal semiconductor thermoelectrical properties hardness thermovision imaging

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The Choice Between Three Simple Methods for Glomerular Filtration Rate Assessment in Different Stages of Chronic Parenchymal Renal Diseases

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Journal of Physical Science and Application 2012年第9期2卷 372-380页

作者： Milena P. Rajic Marina Vlajkovic Slobodan Ilic Milos stevic Vladan Sekulic Ljubinka Velickovi Jankovi Department of Nuclear Medicine University of Nis Medical School and Clinical Center Dr Zoran Dindi6 48 18000 NiJ Serbia Departement of Pathology University of Nis Medical School and Clinical Center Dr Zoran Dindic 48 18000 Nis Serbia

Glomerular filtration rate （GFR） can be measured （mGFR） after intravenous application of indicators that are eliminated by kidneys or estimated （eGFR） using mathematic equations. We have compared eGFR obtained by the chronic kidney diseases epidemiology collaboration （CKD-EPI） and the Modification of diet in renal disease （MDRD） Study equations with GFR measured by technetium-99m diethylene triamine penta-acetic acid （99m^Te-DTPA） renal clearance in different stages of renal diseases in order that obtained results may contribute to more adequate choice of methods for the GFR assessment in relation to the type and stage of kidney disease. The study included a total of 189 participants with diabetes mellitus （DM）, glomerulonephritis （GN）, Balkan endemic nephropathy （BEN） and healthy subjects. 99m^Tc-DTPA clearance （ml/min/1.73 m^2） was calculated from the regression equation based on high correlation between distribution volume of radiopharmaceutical and clearance values obtained by multiple blood samples. For blood sample taken at 3 h and 4 h, clearance was calculated according to the equations： y = -0.0128x^2 ＋ 3.077x - 30.3, and y = -0.00628x^2 ＋ 2.066x - 19.3, where y is clearance, and x is distribution volume. MDRD-GFR （ml/min/l.73 m2） was calculated from equation： 186 × Scr^-1154 × age^-0.203 × 0.742 if female. CKD-EPI-GFR was calculated from equation： 141 × min（Scr/K, 1）^ α ×max（Scr/K, 1）^-1 209 × 0.993age × 1.018 if female, where Scr is serum creatinine, n is 0.7 for females and 0.9 for males, c~ is -0.329 for females and -0.411 for males, min indicates the minimum of Scr/K or 1, and max indicates the maximum of Scr/κ or 1. Irrespective of renal disease, both equations underestimated radionuclide clearance at mGFR 〉 90 ml/min/1.73 m^2 （91.7 ± 18.8 and 88.2 ± 22.0 vs. 121± 19.6, p〈0.0001） and at mGFR 60-89 ml/min/1.73 m^2 （67.1 ±19.9 and 65.8 ± 19.9 vs. 75.8 ± 9.2, p 〈 0.05 and p 〈 0.005）. They were also significantly lower than mGFR in DM patients with GFR 〉_

关键词： Renal disease glomerular filtration rate 99^mTc-DTPA renal clearance CKD-EPI equation MDRD equation.

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