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Search Results: 1 - 10 of 582507 matches for " Veljkovi? Neboj?a D. "
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Dynamics of the process of colour adsorption from waste waters after dyeing textile fibres on natural zeolites
Cibuli? Violeta V.,Stamenkovi? Lidija J.,VeljkoviNeboja D.,Staletovi? Novica M.
Hemijska Industrija , 2013, DOI: 10.2298/hemind120209049c
Abstract: This study analyses the process of purifying waste waters from textile fibre dyeing by adsorption of colour on natural zeolites from “Nemetali” mine, Vranjska Banja, Serbia. The process has been analyzed in an adsorption column filled with natural zeolite as the adsorbent. Adsorbents are organic substances, i.e. colour residues from waste waters, left after textile fibres dyeing. The concentration change in waste waters is represented with the parameter of chemical oxygen demand (COD). Two models of diffusion have been considered: diffusion in pores and diffusion in adsorbent phase on solid adsorbent, for different input loads and two zeolite granulations (13 and 35 mm). It was found that the diffusion in zeolite pores that were in adsorbed phase is dominant in this case, which can be explained by large dimensions of used colours’ molecules. This is the reason why its adsorption in zeolite micro pores is minimal, and yet it diffuse well in already adsorbed phase on solid adsorbents. Since this process is slower, it will determine the overall rate of colour adsorption from waste waters. Specific equilibrium capacity, specific dynamic capacity, as well as the level of adsorbent utilization were determined by the use of mass transfer zone concept. It has been shown that the adsorption of organic substances from waste waters is satisfactory, and is around 80%. The highest degree of adsorbent utilization is obtained at the lowest flow of 0.167 cm3 s-1, while the lowest degree of utilization of 30%, is obtained at the highest flow of 3.27 cm3 s-1. Input load has significant influence on the degree of column utilization, while higher values of COD0 result in lower degrees of column utilization. Key words: waste waters, natural zeolite, adsorption, colour adsorption, textile dyes
Macro and microelements in bottled and tap waters of Serbia
Petrovi? Tanja M.,Zlokolica-Mandi? Milena,VeljkoviNeboja,Papi? Petar J.
Hemijska Industrija , 2012, DOI: 10.2298/hemind110729062p
Abstract: Comparative analysis between bottled and tap waters as well as its comparison with current Serbian regulations, European Union Directives and World Health Organization standard are shown in this paper. Thirteen bottled waters and fourteen tap waters from the territory of Serbia were analyzed in the Federal Institute for Geosciences and Natural Resources (BGR) laboratory in Berlin, for the purpose of the “Geochemistry of European Bottled Water“ project conducted by EuroGeo Survey Geochemistry (EGS). Macrocomponents (main cations and anions) of ground waters usually reflect on lithogeochemistry of the aquifer, while microcomponents indicate the circulation of ground water through the different lithological environment. Analyzed bottled waters could be classified as those with low mineral content (M<500 mg/L) if HCO3 anion and Ca and Mg cations were the prevailing ones, or mineral (M>500 mg/L) with prevailing HCO3 anion and Na cation. Waters with low mineral content were mainly from limestone and dolomite, while mineral waters mainly originated from magmatic and metamorphic rocks. Higher content of Cs, Li, Ge, Rb and F in bottled waters indicates the importance of the magmatic intrusions influence on their chemical composition. In some waters higher content of B, I, NH4, as well as of Tl and W has been observed which can be attributed to water’s circulation through different lithological complexes. Tap water was mostly obtained from groundwater (from Neogen and alluvial aquifers and karst springs) with rest being those of rivers and surface accumulations. Tap waters from Central Serbia were with low mineral content, with prevailing HCO3 anion and Ca and Mg cations, while waters from Vojvodina, the northern province of Serbia, were with higher mineralization, HCO3-Na. Chemical analyses of the sampled tap waters showed good quality, with exception of waters from the cities of Senta and Zrenjanin in Vojvodina. High values of B (1170 and 895 g/L), As (20.9 and 71.9 g/l), Na (208 and 275 mg/L), as well as EC (715 and 928 S/cm) have been registered in these waters.
Formation of the honeycomb-like electrodes by the regime of pulsating overpotential in the second range
NEBOJA D. NIKOLI?,GORAN BRANKOVI?,MIOMIR G. PAVLOVI?
Journal of Electrochemical Science and Engineering , 2012,
Abstract: In this study the honeycomb-like copper structures electrodeposited by the regime of pulsating overpotential in the second range were analyzed by the technique of scanning electron microscopy. The overpotential amplitude of 1000 mV, deposition pulse of 1 s, and pause durations of 1, 5, 10 and 15 s were selected for the production of this type of structures. The size of holes which remained upon detachment of hydrogen bubbles do not depend on the length of pause duration. On the other hand, the change in morphology of electrodeposited copper around holes from cauliflower-like agglomerates of copper grains to degenerated dendrites is observed when pause duration was increased. Effects of the application of the regime of pulsating overpotential in the second range on the formation of the honeycomb-like structures were less pronounced than the effects attained by the application of the same regime in the millisecond range. However, they were more pronounced than those attained by electrodeposition in the regime of constant potential.
A mathematical model of the current density distribution in electrochemical cells - AUTHORS’ REVIEW
KONSTANTIN I. POPOV,PREDRAG M. ?IVKOVI?,NEBOJA D. NIKOLI?
Journal of the Serbian Chemical Society , 2011,
Abstract: An approach based on the equations of electrochemical kinetics for the estimation of the current density distribution in electrochemical cells is presented. This approach was employed for a theoretical explanation of the phenomena of the edge and corner effects. The effects of the geometry of the system, the kinetic parameters of the cathode reactions and the resistivity of the solution are also discussed. A procedure for a complete analysis of the current distribution in electrochemical cells is presented.
Quality assurance of the Serbian national E-PRTR register reported data for large combustion plants
Savi? Marina A.,Red?i? Neboja D.,Jovanovi? Jovan M.,Jovanovi? Mi?a B.
Hemijska Industrija , 2012, DOI: 10.2298/hemind110310065s
Abstract: The Serbian E-PRTR register (The European Pollutant Release and Transfer Register) was established in 2007 and harmonized with PRTR protocol of Arhus convention and E-PRTR directive. In this paper, the quality of 2009 data reported to the Serbian PRTR register was analyzed. The analysis includes 37 large combustion plants with the capacity equal or greater than 50 MW. The combustion plants include power plants, heating plants and industrial energy units. The calculation is done using EMEP/EEA 2009 methodology and Tier 2 approach. The analysis obtained presents an overview of the quality of the reported data for SOx, NOx and TSP emissions for 61 combustion units e.g. emitters (stacks). The results show that all 61 emitters reported data with the deviation greater than 25%, with 55% of the emitters reporting data that differed from pollutant to pollutant in comparison to the estimated data. Out of those, 30% of the emitters reported smaller and 8% reported greater emissions than estimated emissions with 7% of the emitters not submitting any emissions data. The analysis also includes calculation of the emissions scope limit within 95% confidence interval. According to these results, it can be concluded that only 15% of the emitters have emission levels that fall within the scope limits, 47% of the emitters reported data of which two data fall within the scope limits, 28% of the emitters reported data of which only one data fall within the scope limits, 3% of the emitters had data that didn’t fall within the scope limits, and 7% did not reported any emission data. The results of the analysis can be summarized as: 1) operators in facilities do not know how to calculate emissions from their sources, and 2) the application of global emission factors can lead to considerable errors. The main reasons for significant deviation are different fuel quality, type of technical units and human error, thus national emission factors should be developed.
Liver actinomycosis mimicking liver tumor
?ulafi? ?or?e M.,Leki? Neboja S.,Kerkez Mirko D.,Mija? Dragana D.
Vojnosanitetski Pregled , 2009, DOI: 10.2298/vsp0911924c
Abstract: Background. The liver actinomycosis is a rare disease associated with complex differentiation from the liver metastases or hepatocellular carcinoma. Case report. A 50-year old immunocompetent female patient was admitted to the Surgical Department in an exhausted condition, with dyspnea, significant weight loss and intermittent fever in the recent two months. Diagnostic procedures that followed, including abdominal ultrasound and computed tomography led us to the diagnosis of metastatic liver disease of unknown etiology with pleural and pericardial effusion. Intraoperatively, the presence of liver pseudotumor without malignancy in the liver was confirmed. Histological examination confirmed the diagnosis of liver actinomycosis. Prolonged treatment with high dose penicillin was performed and all signs and symptoms resolved completely without further problems. The control abdominal ultrasound finding was normal. Conclusion. Liver actinomycosis has a nonspecific presentation, often mimicking liver tumor. A timely diagnosis as well as a combined surgical and antibiotic therapy is necessary in the treatment of patients with primary disease and prevention of complications.
Multiple port-site metastasis of incidental gallbladder carcinoma after laparoscopic cholecystectomy
Ra?natovi? Zoran J.,Zari? Nemanja D.,Galun Danijel A.,Leki? Neboja S.
Acta Chirurgica Iugoslavica , 2012, DOI: 10.2298/aci1201105r
Abstract: Laparoscopic cholecystectomy is a surgical procedure of choice for benign gallbladder diseases. In about 1-2% of cases histopathological examination demonstrate incidental gallbladder cancer (GBCA). We report a case of a 61 year old woman who developed port site metastases after laparoscopic cholecystectomy for adenocarcinoma of the gallbladder. Metastases appeared on all four port sites. Review of literature regarding incidental GBCA an port site metastases was also performed. We conclude that the retrieval bag should be routinely used in laparoscopic cholecystectomy; the procedure should be performed with minimal trauma; in cases of incidental GB carcinoma, full thickness excision of the abdominal wall of the port sites demands additional studies; additional liver bed excision and local lymphadenectomy for T1b carcinoma are yet to be considered.
Synthesis, structure and solvatochromism of 5-methyl-5-(3- or 4-substituted phenyl)hydantoins
NATALIJA D. DIVJAK,NEBOJA R. BANJAC,NATA?A V. VALENTI?,GORDANA S. U??UMLI?
Journal of the Serbian Chemical Society , 2009,
Abstract: Several 5-methyl-5-(3- or 4-substituted phenyl)hydantoins were prepared and their ultraviolet absorption spectra were recorded in the region 200–400 nm in twelve solvents of different polarity. The effect of solvent dipo larity/polarizability and solvent/solute hydrogen bonding interactions were analyzed by means of the linear solvation energy relationship (LSER) concept proposed by Kamlet and Taft. The lipophilic activity of the investigated hydantoins was estimated by calculation of log P values with Advanced Chemistry Development Software. The calculated values of log P were correlated with the contribution of hydrogen bond donor–solvent interactions. By employing the thus obtained linear dependence, the pharmacological activity of the studied hydantoin derivatives is discussed.
On the Simplex Algorithm Initializing
Neboj a V. Stojkovi ,Predrag S. Stanimirovi ,Marko D. Petkovi ,Danka S. Milojkovi
Abstract and Applied Analysis , 2012, DOI: 10.1155/2012/487870
Abstract: This paper discusses the importance of starting point in the simplex algorithm. Three different methods for finding a basic feasible solution are compared throughout performed numerical test examples. We show that our two methods on the Netlib test problems have better performances than the classical algorithm for finding initial solution. The comparison of the introduced optimization softwares is based on the number of iterative steps and on the required CPU time. It is pointed out that on average it takes more iterations to determine the starting point than the number of iterations required by the simplex algorithm to find the optimal solution.
Single-incision laparoscopic cholecystectomy: Initial experience with different multichannel ports
Ra?natovi? Zoran J.,Zari? Nemanja D.,?ura?i? Ljubomir M.,Leki? Neboja S.
Acta Chirurgica Iugoslavica , 2012, DOI: 10.2298/aci1201067r
Abstract: Single-incision laparoscopic cholecystectomy is a relatively new minimally invasive surgical technique in treatment of benign gallbladder diseases. It is considered a bridge technique between conventional laparoscopic cholecystectomy (LC) and NOTES. We are presenting our initial experiences in SILC (single-incision laparoscopic cholecystectomy). Seventeen patients underwent SILC (11 women and 6 men) with an average age of 43 years. Mean BMI score was 29,4 kg/m2. The mean operative time was 93,5 minutes. There were conversions to conventional LC in two cases (11,6%). Average pain score measured on visual-analogue scale (VAS) 8h after the operation was 2,00. All patients expressed satisfaction with achieved cosmetic effect. We conclude that SILC is safe and feasible procedure, with excellent cosmetic effect, but further prospective studies are required before SILC can be generally accepted.
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