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Experimental study and thermodynamic remodeling of the Bi-Cu-Ni system
No full textPhase equilibria in the Bi-Cu-Ni ternary system have been studied using differential thermal analysis (DTA) as well as by using the calculation of the phase diagram (CALPHAD) method. Literature experimental phase equilibria data and DTA results from this study were used for thermodynamic modeling of the Bi-Cu-Ni ternary system. Isothermal sections at 300, 400, and 500 degrees C, vertical sections from bismuth corner with molar ratio Cu:Ni = 1/3, 1/1 and 3/1 and vertical section at 40 at.% Cu were calculated and compared with corresponding experimental results. Reasonable agreement between the calculated and experimental data was observed in all cases
The nucleation of K2O center dot TiO2 center dot 3GeO(2) glass under non-isothermal conditions
No full textThe nucleation of germanate K2O center dot TiO2 center dot 3GeO(2) glass under non-isothermal conditions was studied by the DTA method. The temperature ranges of nucleation and crystal growth of this glass partly overlap. The influence of the mass of the glass sample as well as, the time and temperature of the pre-DTA heat treatment on the DTA parameters T-p, (delta T)(p), and Delta T-p was investigated. A complex behavior of these parameters was evidenced. It was shown that for fixed temperatures, increasing the annealing time of the pre-DTA heat treatment resulted in a decrease in the temperature of the DTA peak (T-p). The curve of the dependence of DTA peak heights (delta T)(p) on time showed a maximum and the parameter Delta T-p continually increased with increasing time. The influence of the temperature of the pre-DTA heat treatment on the DTA parameters showed that for annealing times t>t(ind), the dependences of T-p(-1) and Delta T-p vs. T corresponded to the dependence of Ion Tin the case when the regions of I and U partly overlapped. As shown, in this case. the change of (delta T)(p) vs. T is not convenient for an analysis of the nucleation behavior of the glass
Effect of copper production of environment and biodiversity
No full textKonvencionalni pirometalurški postupak za dobijanje bakra obuhvata sledeće faze: prženje koncentrata bakra, topljenje nastalog prženca, konvertorovanje bakrenca i plamenu rafinaciju. Anodni bakar se nakon toga podvrgava elektrolitičkoj rafinaciji, pri čemu se dobija elektrolitički bakar. Sadržaj bakra u koncentratima se kreće u vrlo širokim granicama (10-40%), a to zavisi od hemijskog i mineraloškog sastava rude. Pored minerala bakra, u koncentratima su prisutni i sulfidi olova, cinka, nikla, žive, arsena, kadmijuma i antimona, minerali jalovine, kao i retki i plemeniti metali. U procesu pirometalurške prerade koncentrata bakra, prisutne primese, od kojih su neke toksične, raspodeljuju se između nastalih međuprodukata i krajnjih produkata. Naročito velike poteškoće, pri preradi koncentrata, predstavljaju isparljiva jedinjenja, koja prelaze u gasovito stanje i odlaze sa gasnom smešom u atmosferu. U radu su prikazani rezultati uticaja pojedinih prisutnih komponenti iz koncentrata bakra, na promene koje se odvijaju u životnoj sredini, što za posledicu, između ostalog ima i narušavanje, pa i gubljenje biološkog diverziteta. .Pyrometallurgical conventional procedure for obtaining copper includes the following phases: copper concentrate roasting, melting, converting and anode refining. Anodic copper is then subjected to electrolytical refining, where electrolytic copper is produced. Content of copper in concentrates is varying a very wide limits (10-40%), and it depends on the chemical and mineralogical composition of the ore. Besides copper minerals, copper concentrates contain the sulphides of lead, zinc, nickel, mercury, arsenic, cadmium and antimony, waste. In the process of pyrometallurgical processing of copper concentrates, the ingredients, some of which are toxic, are distributed between the formed intermediates and final products. Especially great difficulty in processing the concentrates are the volatile compounds, which change into gaseous state and go to the atmosphere with the process gasses. This paper presents the results of the impact of certain components present in the copper concentrate, the changes that occur in the environment, resulting, among other things, with a loss of biological diversity.
The Effect of the Uranium Content in the Tailings on Some Cultivated Plants
No full textUranium is a radiotoxic and chemotoxic heavy metal. Uptake and accumulation of U has been studied in plants native to uranium mine sites, but not in cultivated plants which are commonly consumed by humans. The objective of this study was better understanding of U uptake and accumulation in cultivated plants and whether different contents of uranium (U) in the substrate affect its concentration in plants and their dry matter mass. Two substrate variants for growing plants, which differed in the uranium content: solid wastes (tailings) and tailings mixed with sand (w/w 1:1). Large amounts of solid wastes (tailings) resulting from the exploitation and treatment of uranium ore from the closed uranium mine Gabrovnica-Kalna, on southeast of Serbia, contained generally 15.33 mg U/kg. In the experiment, three plant species (corn NSSC 231, sunflower N.S. Dukat, and green peas Smederevska Palanka) were grown in pots on the four substrate variants during 40 days. Substrate was suffused by drinking water (DW) and "uranium water" (UW), which issue out from the mine, contained 0,053 mg U/ dm(3). Obtained results show that when UW was added to tailing concentration of U in plants increased. When the content of U in the substrate was lowered by adding sand, the concentration of U in plants decreased, though was significantly higher in comparison to the variants to which DW was added. Dry matter mass was higher in variants where UW was used. Concentration of U was significantly higher in root than in above-ground parts
Non-isothermal crystallization of k2o center dot tio2 center dot 3geo(2) glass
No full textThe crystallization of K2O center dot TiO2 center dot 3GeO(2) glass under non-isothermal condition was studied. In powdered glass with particle sizes less than 0.15 mm, surface crystallization was dominant and an activation energy of crystal growth of E-a,E-s = 327 +/- 50 kJ mol(-1) was calculated. In the size range 0.15 to 0.45 mm, both surface and volume crystallization occurred. For particle sizes >0.45 mm, volume crystallization dominated with spherulitic morphology of the crystals growth and E-a,E-v = 359 +/- 64 kJ mol(-1) was calculated
Electrodeposited hydroxyapatite thin films modified by ion beam irradiation
No full textSurface modification of hydroxyapatite (HA) thin films electrodeposited on titanium was conducted by ion implantation, using nitrogen and argon ions at different constant fluences of 1x10(15), 1x10(16) and 1x10(17) ions/cm(2). SEM and XRD analysis, as well as SRIM calculation, were used to monitor the changes induced by ion bombardment. In the case of HA film implanted with N4+ ions, the unit cell parameters and unit cell volume increase with increasing nitrogen ion fluences. Similarly, the unit cell parameters and unit cell volume increase after Ar6+ ions irradiation to a 1x10(15) ions/cm(2). At higher fluences, the unit cell parameters and unit cell volume decrease when argon ion fluences increase to 1x10(16) and 1x10(17) ions/cm(2). These structural changes are consequence of different mechanism of energy transfer of nitrogen and argon ions to HA film. For nitrogen ion irradiation electron energy loss is predominant, while for argon ion irradiation nuclear energy transfer to HA film prevails
Electrochemical synthesis of nanosized monetite powder and its electrophoretic deposition on titanium
No full textElectrochemical synthesis of nanosized monetite powder was performed galvanostatically from homogeneous Solution of Na(2)H(2)EDTA center dot 2H(2)O, NaH2PO4 and CaCl2 at a concentration relationship Ca/EDTA/PO43- of 0.25/0.25/0.15 M at current density of 137 mA cm(-2) and pH value of 5.0. The synthesized monetite powder was characterized by X-ray diffraction, infrared spectroscopy, size distribution measurements, thermogravimetric and differential thermal analysis and scanning electron microscopy. Monetite powder was electrophoretically deposited on titanium from ethanol Suspension, using constant voltage method. The deposition was performed at constant voltage between 10 and 50 V and for a constant deposition time between 1 and 30 min. The influence of the applied voltage and deposition time on the mass and morphology of monetite deposits was investigated. It was shown that monetite deposits of the highest thickness and the lowest porosity can be formed at lower applied voltage (30 V) and for longer deposition time (20 min) and then converted to hydroxyapatite
The nucleation behavior of k2o center dot tio2 center dot 3geo(2) undercooled melt
No full textThe nucleation of K2TiGe3O9 crystals in an undercooled melt of stoichiometric composition was studied. Volume nucleation with spherical morphology of the growing crystals was determined. The nucleation range is in the temperature interval 540-630 degrees C. A maximum of the steady state nucleation rate of I-max = 1.4 x 10(15) m(-3).s(-1) was determined at the temperature T-n(max) = 582 degrees C. The temperature and time dependence of the nucleation rate was analyzed and it was shown that such a nucleation behavior was the result of a low thermodynamic and kinetic barrier. The results showed that the temperature intervals of nucleation and crystal growth of this undercooled melt partly overlapped
Mycotoxic porcine nephropathy and spontaneous occurrence of ochratoxin A residues in kidneys of slaughtered swine
No full textU cilju sticanja saznanja o zastupljenosti mikotoksične nefropatije svinja i uticaja OTA na vrstu i lokalizaciju patomorfoloških promena na bubrezima, na liniji klanja tokom veterinarsko-sanitarnog pregleda redovno zaklanih svinja poreklom sa farmi iz Vojvodine i Srbije, uzimani su uzorci bubrega za analizu. Tokom šestomesečnih ispitivanja ukupno je analizirano 90 uzoraka bubrega zaklanih svinja. Prisustvo rezidua OTA u uzorcima bubrega poreklom iz ispitivanih regiona utvrđeno je kod 33,3% ispitanih uzoraka, u količini od 0,17 do 52,5 ng/g. Zastupljenost rezidua OTA bila je najveća u uzorcima bubrega poreklom sa lokaliteta Senta i Bogatić (36,6%), dok je najveći prosečan sadržaj rezidua OTA (-2,2 μg/kg) utvrđen u uzorcima bubrega poreklom sa lokaliteta Bogatić. Patohistološkim pregledom bubrega najčešće su utvrđene tubulopatije sa edemom i vakuolizacijom ćelija. Takođe, utvrđene su hemoragije i nekroza ćelija proksimalnih bubrežnih tubula.In order to find information on the occurrence of mycotoxic porcine nephropathy in Serbia, during a six month period (2006/2007) samples of kidney from individual healthy slaughtered pigs were collected (n=90) and analyzed by HPLC for ochratoxin A. In addition, histological examinations were carried out. The incidence of OTA in kidney was 33,3% and varied between 0.17-52.5 ng/g. Histopathological examination of kidneys confirmed tubulopathies with oedema and cell vacuolization. In addition, hemorrhages and necrosis of proximal kidney tubules cells were found. These findings indicate that it is likely that most of the kidney injury is related to ochratoxin A and other nephrotoxic compounds which enhance the toxicity of OTA
Some novel insights into the binding of oseltamivir and zanamivir to H5N1 and N9 influenza virus neuraminidases: a homology modeling and flexible docking study
No full textIn the context of the recent pandemic threat by the worldwide spread of H5N1 avian influenza, novel insights into the mechanism of ligand binding and interaction between various inhibitors (zanamivir - ZMV, oseltamivir - OTV, 2,3-didehydro-2-deoxy-N-acetylneuraminic acid - DANA, peramivir - PMV) and neuraminidases (NA) are of vital importance for the structure-based design of new anti-viral drugs. To address this issue, three-dimensional models of H5N1-NA and N9-NA were generated by homology modeling. Traditional residues within the active site throughout the family of NA protein structures were found to be highly conserved in H5N1-NA. A subtle variation between lipophilic and hydrophilic environments in H5N1-NA with respect to N9-NA was observed, thus shedding more light on the high resistance of some H5N1 strains to various NA inhibitors. Based on these models, an ArgusLab4/AScore flexible docking study was performed. The conformational differences between OTV bound to H5N1-NA and OTV bound to N9-NA were structurally identified and quantified. A slight difference of less than 1 kcal mol(-1) between the OTV-N9 and OTV-N1 binding free energies is in agreement with the experimentally predicted free energy difference. The conformational differences between ZMV and OTV bound to either H5N1-NA or N9-NA were structurally identified. The binding free energies of the ZMV complexes, being slightly higher than those of OTV, are not in agreement with what was previously proposed using homology modeling. The differences between-ZMV and OTV are suggested to be ascribed to the presence/absence of Asn 166 in the active cavity of ZMV/OTV in H5N1-NA, and to the presence/absence of Ser165 in the binding site of ZMV/OTV in N9-NA. The charge distribution was evaluated using the semi-empirical AMI method. The trends of the AMI charges of the ZMV and OTV side chains in the complexes deviate from those previously reported