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Uranium distribution in broiler organs and possibilities for protection
No full textThe aim of the present study was to investigate the distribution of uranium (uranyl nitrate hexahydrate, UN) in muscle and organs (kidney, liver, and brain) of broilers, after a 7-day contamination with UN and administration of two different adsorbents (organobentonite and organozeolite). The birds were contaminated during 7 days with 25 mg/UN per day. Adsorbents were given via gastric tube, immediately after contamination with UN. In group 1 that did not receive any adsorbents, histopathological changes in the contaminated broilers were observed in small intestine, liver, and kidney in the form of necrosis of intestinal villi, oedema and cytoplasmic vacuolation of hepatocytes, and dystrophic changes in the kidney tubules epithelium. Organobentonite administered via gastric tube (group 2) reduced uranium distribution by 66 % in kidney, 81 % in liver, and 34 % in brain. In group 3, administration of organozeolite reduced uranium distribution by 67 % in kidney, 68 % in liver, and 49 % in brain. In groups 2 and 3, where the broilers received adsorbents immediately after the UN contamination, no histopathological lesions were observed
The possibilities of obtaining metallic calcium from Serbian carbonate mineral raw materials
No full textEksperimentalnim istraživanjima su definisani kako tehnološka šema dobijanja kalcijuma iz krečnjaka aluminotermijskim procesom tako i osnovni radni parametri pojedinih tehnoloških faza. Uzorci krečnjaka koji su korišćeni u radu imaju visok sadržaj Mg, Na i K. Rendgenska analiza je pokazala da uzorci uglavnom sadrže kalcit i u manjoj količini dolomit. Na početku je ispitan uticaj temperature, vremena i granulometrijskog sastava na kalcinaciju kalcijum-karbonata. Vreme trajanja procesa disocijacije je 10-15 min na 1200 °C i povećava se sa smanjenjem veličine čestica do 5 mm. Nakon toga, ispitana je aluminotermijska redukcija kalcijum-oksida. Na temperaturi od 1200 °C i vakuumu od 3 KPa proces redukcije se završava za 2 h. Analiza hemijskog sastava kalcijum-oksida i kalcijuma pokazuje povećan sadržaj magnezijum-oksida i oksida alkalnih metala, posebno natrijuma.We present experimental investigations that define both the technological scheme of calcium production from limestone by aluminothermic process and the basic operating parameters of the particular technological phases. The limestone with high content of Mg, Na and K was used in the study. X-ray analysis reveals that the samples contain mainly calcite with small amount of dolomite. At first, the effects of temperature, time and granulometry on the calcium carbonate calcination were examined. The dissociation process was completed in 10-15 min at 1200 °C, and the dissociation rate increased with decreasing particle size down to 5 mm. Afterwards, the aluminothermic reduction process of calcium oxide was investigated. At a temperature of 1200 °C and vacuum of at least 3 kPa, the reduction process completed within 2 h. The chemical composition of calcium oxide and calcium showed increased content of magnesium oxide and alkaline oxides (especially sodium)
Influence of chalcopyrite structure on their leaching by sodium nitrate in sulphuric acid
No full textDuring the chalcopyrite leaching by sodium nitrate and sulfuric acid solution, leaching rate decreases with increasing the time and a part of chalcopyrite mineral grains remains in the leach residue. In chalcopyrite concentrate, 95.5 % of chalcopyrite mineral occurs as in liberated grains, and the rest is in association with gangue minerals, which is very favorably from the aspect of hydrometallurgical treatment. Complex forms, like impregnations and complex intergrowths, do not exist. After experiments carried out, leaching of copper achieved 84 % at temperature 80 degrees C and time 240 min. In the all leach residues, 97 % chalcopyrite mineral grains occur as liberated with highly corroded surfaces. Therefore, the structural assembly of chalcopyrite grains is favorable and no reason to reduce the leaching rate in the final stage of reaction. Reason for this is elemental sulfur, which was formed during the reaction, precipitated at the particle surfaces, and slowed down the leaching rate in the final stage of leaching process
Utilization of Phosphate Rock from Lisina for Direct Application: Release of Plant Nutrients in the Exchange-Fertilizer Mixtures (vol 62, pg 9965, 2014)
No full textInorganically modified diatomite as a potential prolonged-release drug carrier
No full textInorganic modification of diatomite was performed with the precipitation product of partially neutralized aluminum sulfate solution at three different mass ratios. The starting and the modified diatomites were characterized by SEM-EDS, FTIR, thermal analysis and zeta potential measurements and evaluated for drug loading capacity in adsorption batch experiments using diclofenac sodium (DS) as a model drug. In vitro drug release studies were performed in phosphate buffer pH 6.8 from comprimates containing: the drug adsorbed onto the selected modified diatomite sample (DAMD), physical mixture of the drug with the selected modified diatomite sample (PMDMD) and physical mixture of the drug with the starting diatomite (PMDD). In vivo acute toxicity testing of the modified diatomite samples was performed on mice. High adsorbent loading of the selected modified diatomite sample (similar to 250 mg/g in 2 h) enabled the preparation of comprimates containing adsorbed DS in the amount near to its therapeutic dose. Drug release studies demonstrated prolonged release of DS over a period of 8 h from both DAMD comprimates (18% after 8 h) and PMDMD comprimates (45% after 8 h). The release kinetics for DAMD and PMDMD comprimates fitted well with Korsmeyer-Peppas and Bhaskar models, indicating that the release mechanism was a combination of non-Fickian diffusion and ion exchange process
Assessment of lipophilicity of some biologically active arylpiperazines by rptlc and multivariate analysis
No full textThe chromatographic behavior of arylureas and arylacetamides derivatives with observed biological activity toward dopamine D-2 and 5-hydroxytryptamine 5HT(1A) receptors were examined by high-performance thin-layer chromatography in order to determine their lipophilicity and to correlate their structure and retention. The binary water-dimethyl sulfoxid mobile phases and RP-18 silica as stationary phase were used in order to determine chromatographic descriptors R-M(0), b, and C-0, as a measure of the lipophilicity of tested compounds. Based on the respective retention, the lipophilicity of the investigated compounds was discussed. Principal component analysis followed by partial least squares was used to select variables that best describe the behavior of the investigated compounds in the chromatographic system and to quantify their influences. The models reveal the importance of nonpolar properties of the solutes and their ability for hydrophobic interactions, as well as the importance of proton donating abilities and the size and the shape of the molecule, pointing out on that way the possible separation mechanism in the studied chromatographic systems
Rujevac Sb-Pb-Zn-As polymetallic deposit, Boranja orefield, Western Serbia: native arsenic and arsenic mineralization
No full textRujevac is a low-temperature hydrothermal polymetallic Sb-Pb-Zn-As vein-type ore deposit, hosted within a volcanogenic-sedimentary zone situated in the Rujevac-Crvene Stene-Brezovica Diabase-Chert Formation (DCF) of the Podrinje Metallogenic District (PMD), Serbia. It is located several kilometers SE from the Boranja contact aureole, which is an integral part of the PMD in Western Serbia. Genetically related to the Tertiary granodioritic magma, the mineral assemblages are characterized by specific features. The mineral association of this deposit consists of sulfides, Pb-Sb(As) sulfosalts, native metals, oxides, hydroxides and gangue minerals. Chemical composition of the ore is very complex, where contents of valuable metals range as follows: Sb (0.17-24.31 wt.%), Zn (0.21-6.29 wt.%), Pb (0.15-6.33 wt.%), As (0.06-1.28 wt.%), Cd (25-747 ppm), Ag (7-408 ppm), Hg (13-473 ppm), and Tl ( LT 1-29 ppm). Electron Probe Microanalyses (EPMA) of native arsenic from both the Rujevac and Stragari deposits showed contents of As up to 98.8 and 97.1 wt.%, with impurity contents of Sb up to 1.3 and 6.6 wt.%, and Tl up to 2 and 1.3 wt.%, respectively. Rhombohedral unit-cell parameters for native arsenic from Rujevac and Stragari deposits amount to: a=3.760(2), c=10.555(3) angstrom, V=129.23(7) angstrom(3) and a=3.763(1), c=10.560(5) angstrom, V=129.48(8) angstrom(3), respectively. Mineral assemblages, deposition order and genesis of the Rujevac polymetallic deposit were also discussed in detail. Native arsenic mineralization here has been additionally compared with similar well-known global deposits
Srebrenica orefield, podrinje metallogenic district, Republic of Srpska, BiH: hydrated fe(al)-phosphates and their parageneses within the pb-zn mineralization
No full textThe Srebrenica orefield is mostly composed of Tertiary dacite-andesites, and quartz latites, pyroclastites, Paleozoic schists, and Quaternary sediments, but in a in a lesser extent. The latest research showed that in the Srebrenica orefield occur complex mineral parageneses and associations deposited in pneumatolytic-hydrothermal and hydrothermal (from high- to low-temperature) stage, accompanied with very rare minerals. Beside ore mineral parageneses and associations, specials emphasis was on rare hydrated phosphates: vivianite, ludlamite, and vauxite. It is important to say that vauxite from the Srebrenica orefield is fourth discovery in the world. The minerals above were studied using DTA-TGA, IR-spectroscopy, and XRPD
Pb(II) removal from aqueous solution by Myriophyllum spicatum and its compost: equilibrium, kinetic and thermodynamic study
No full textBACKGROUND Lead is one of the frequent contaminants of industrial wastewater. Since it has been shown that aquatic plants can be used for the removal of heavy metals, herein Pb(II) biosorption by Myriophyllum spicatum and its compost were investigated. Effects of pH, ionic strength and contact time were analyzed using a batch experiment. Biomasses were characterized chemically and by Fourier transform infrared spectroscopy, scanning electron microscopy and X-ray diffraction techniques. RESULTS The adsorption process of both biosorbents followed a pseudo-second-order kinetic model. Compost exhibits better Pb(II) removal from solution (71%) compared with the plant (61%). Lead binding capacities for M. spicatum and its compost were 0.234 mmol g(-1) and 0.287 mmol g(-1) at pH 5.0, respectively. Lead binding takes place mainly through an ion exchange mechanism, but chemisorption via identified functional groups cannot be neglected. The Langmuir, Freundlich and Sips adsorption models for compost were applied. The Sips isotherm model gave the best fit with the equilibrium experimental data. The sorption process by compost was endothermic and spontaneous. CONCLUSION Aquatic weed compost as a low cost biosorbent with high biosorption capacity can potentially be used for the removal of lead from wastewaters
Effect of Tempering on Mechanical Properties and Microstructure of a High-Strength Low-Alloy Steel
No full textThe effect of tempering at 450 - 650A degrees C of different duration on mechanical properties and microstructure of a cast low-alloy steel is investigated. The ultimate rupture strength, the yield strength, the elongation and the Vickers hardness of the steel are determined. Metallographic analysis is performed