Papers by Maja Stevanović
Macedonian Journal of Chemistry and Chemical Engineering
A series of bimetallic Sn-Pd catalysts were prepared by a template-free two step electrodepositio... more A series of bimetallic Sn-Pd catalysts were prepared by a template-free two step electrodeposition method. According to this method, Sn was electrodeposited firstly in potentiostatic or galvanostatic regime on Cu electrodes in the form of dendrites, then Pd was galvanostatically electrodeposited in the second step on the electrode with the electrodeposited Sn dendrites. The produced Sn-Pd electrocatalysts were compared with an electrocatalyst obtained by Pd electrodeposition on a bare Cu electrode. The morphological and elemental analysis of Sn-Pd and Pd electrocatalysts was performed by means of scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) techniques. The dendrites of various shapes and degree of branching were obtained by Sn deposition depending on electrodeposition regime, while Pd was electrodeposited in a form of compact Pd islands on both Sn dendrites and the Cu electrode. Cyclic voltammetry (CV) was applied for the electrochemical examinat...
Introduction/Objective Patients who have had symptoms for more than 12h before receiving treatmen... more Introduction/Objective Patients who have had symptoms for more than 12h before receiving treatment are considered to be myocardial infarction late presenters. The literature contains scarce and often controversial data about treating such patients. The objective of the paper is to present treatment outcome in patients with acute ST-elevation myocardial infarction (STEMI), whose therapy was initiated more than 12h and less than 48 hours after the onset of symptoms. Methods the research included 130 patients who had suffered from acute STEMI in 2017, all of whom presented more than 12h and less than 48h after the onset of symptoms. A primary percutaneous coronary intervention (PPCI) was used to treat 109 patients, while 21 patients were treated conservatively. An analysis was performed correlating treatment results, intrahospital mortality, one-year survival rate depending on the type of treatment, risk factors and comorbidity. Results A statistically significant difference (x 2 =7,11...
Zastita materijala, 2016
In this paper, phenomena of chemical corrosion of metals and alloys in electrolyte solutions are ... more In this paper, phenomena of chemical corrosion of metals and alloys in electrolyte solutions are analyzed. It is shown that iron, chromium and other metals and alloys dissolve much faster than is the corrosion rate determined by electrochemical methods. This means that the chemical dissolution takes place simultaneously with the electrochemical dissolution. The chemical dissolution does not depend on electrode potential. Under some conditions, chemical dissolution of metals is the dominant process of dissolution. Several mechanisms of chemical corrosion are described. Also, the consequences of chemical dissolution of various metals and alloys are discussed, as well as the hydrogen evolution during the chemical dissolution. The process of hydrogen evolution during the chemical corrosion is not subjected to the laws of electrochemical kinetics.
Mining and Metallurgy Engineering Bor, 2015
In this work, the mechanisms of hydrogen evolution on the metal chromium in a solution of 0.1 M N... more In this work, the mechanisms of hydrogen evolution on the metal chromium in a solution of 0.1 M Na 2 SO 4 + H 2 SO 4 , pH 1 to pH 7 were analysed. In the pH < 3 range, hydrogen is evolved according to three different mechanisms, depending on the experimental conditions: electrochemical evolution of H 2 by reaction of H + ions according to the Volmer-Heyrovsky mechanism, on the bare chromium surface, during chemical dissolution of chromium by the Kolotyrkin mechanism, which does not depend on the electrode potential, and electrochemical hydrogen evolution by the Volmer-Heyrovsky mechanism, but on the passive chromium. At pH values greater than 3, the fourth mechanism of hydrogen evolution is observed, that is electrochemical reaction of water molecules on the surface of oxide covered chromium surface.
Zastita materijala, 2015
Određivanje brzine korozije metala šava u zavarenom spoju pomoću elektrohemijskih tehnika IZVOD Z... more Određivanje brzine korozije metala šava u zavarenom spoju pomoću elektrohemijskih tehnika IZVOD Za određivanje brzine korozije osnovnog metala i metala šava u zavarenom spoju primenjene su elektrohemijske tehnike: linearna polarizaciona otpornost, voltametrija sa linearnom promenom potencijala i elektrohemijska impedansna spektroskopija. Uzorci za ispitivanje dobijeni su elektrolučnim zavarivanjem čeličnog kotlovskog lima, uz upotrebu obloženih bazičnih elektroda. Pri zavarivanju je korišćena fabrička elektroda i elektrode koje su proizvedene u laboratorijskim uslovima (tanko obložena i debelo obložena bazična elektroda). Utvrđeno je da je brzina korozije metala šava veća od brzine korozije osnovnog metala. Brzina korozije metala šava dobijenog pomoću tanko obložene elektrode je manja od brzine korozje metala šava dobijenog pomoću debelo obložene i fabričke elektrode. Vrednosti za brzinu korozije, određene različitim elektrohemijskim tehnikama, su u saglasnosti.
Mining and Metallurgy Engineering Bor, 2015
The influence of temperature on electrochemical and chemical dissolution of chromium was studied ... more The influence of temperature on electrochemical and chemical dissolution of chromium was studied in the acidic sulphuric solutions. The hydrogen evolution reaction, as well as the anodic dissolution and chemical dissolution of chromium from activated surfaces in sulphuric acid solutions pH 1 follow the Arrhenius law, with the apparent activation energies of 35 kJ mol-1 , 58 kJ mol-1 and 62 kJ mol-1 , respectively. The higher activation energy of the chemical dissolution of chromium leads to the signifycantly noticeable chemical corrosion on elevated temperatures in comparison with the electrochemical corrosion.
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Papers by Maja Stevanović