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Search Results: 1 - 10 of 202540 matches for " Markovi? Jelena P. "
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Kinetic modeling of heavy metal sorption by vinyl pyridine based copolymer
Maksin Danijela D.,Kljajevi? Sla?ana O.,?oli? Maja B.,MarkoviJelena P.
Hemijska Industrija , 2012, DOI: 10.2298/hemind121002112m
Abstract: Commercial macroporous poly(4-vinylpyridine-co-divinylbenzene) [P4VPD], known as REILLEX-425 was characterized by mercury porosimetry, nitrogen physisorption, Fourier transformed infrared (FTIR) spectroscopy and elemental analysis. Sorption rates of P4VPD for Cu(II), Co(II) and Cr(VI) ions were determined in static non-competitive experiments, at room temperature (298 K). Rapid sorption was observed, especially for Co(II), with half time, t1/2, of 1.5 min and high experimental maximal capacity, Qmax, of 3.08 mmol g-1. Four kinetic models (pseudo-first and pseudo-second order model, intraparticle diffusion and Boyd model) were used for analyzing metal sorption by P4VPD. Metal ions sorption is well represented by the pseudo-second-order model, with definite influence of pore and film diffusion on sorption rates. [Projekat Ministarstva nauke Republike Srbije, br. III43009]
Applicability of linearized Dusty Gas Model for multicomponent diffusion of gas mixtures in porous solids
MarkoviJelena,Omorjan Radovan
Acta Periodica Technologica , 2007, DOI: 10.2298/apt0738075m
Abstract: The transport of gaseous components through porous media could be described according to the well-known Fick model and its modifications. It is also known that Fick’s law is not suitable for predicting the fluxes in multicomponent gas mixtures, excluding binary mixtures. This model is still frequently used in chemical engineering because of its simplicity. Unfortunately, besides the Fick’s model there is no generally accepted model for mass transport through porous media (membranes, catalysts etc.). Numerous studies on transport through porous media reveal that Dusty Gas Model (DGM) is superior in its ability to predict fluxes in multicomponent mixtures. Its wider application is limited by more complicated calculation procedures comparing to Fick’s model. It should be noted that there were efforts to simplify DGM in order to obtain satisfactory accurate results. In this paper linearized DGM, as the simplest form of DGM, is tested under conditions of zero system pressure drop, small pressure drop, and different temperatures. Published experimental data are used in testing the accuracy of the linearized procedure. It is shown that this simplified procedure is accurate enough compared to the standard more complicated calculations.
Docking Studies and α-Substitution Effects on the Anti-Inflammatory Activity of β-Hydroxy-β-arylpropanoic Acids
Jelena S. Savi?,Sanda P. Dilber,Bojan D. Markovi,Marina T. Milenkovi?,Sote M. Vladimirov,Ivan O. Jurani?
Molecules , 2011, DOI: 10.3390/molecules16086645
Abstract: Six β-hydroxy-β-aryl propanoic acids were synthesised using a modification of Reformatsky reaction which has already been reported. These acids belong to the aryl propanoic acid class of compounds, structurally similar to the NSAIDs, such as ibuprofen, and an anti-inflammatory activity is thus expected. The aim of this work was to determine anti-inflammatory activity, examine gastric tolerability, and to carry out molecular docking experiments to identify potential COX-2 inhibitors among the β-hydroxy-β-aryl propanoic acids, and to elucidate the effect α-methyl substitution on the anti-inflammatory activity. Anti-inflammatory activity and gastric tolerability were determined on rats using carragenan induced paw oedema method, and docking studies were carried out using Autodock v4.0.1. The range of ED50 values is between 127 μmol/kg and 15 μmol/kg, while the result for ibuprofen is 51.7 μmol/kg. Only slight hyperaemia or few petechiae were spotted on rat’s stomach. The results indicate that all compounds possess significant anti-inflammatory activity after oral administration, and that 2-methyl-3-hydroxy-3,3-diphenyl-propanoic acid has greatest activity, surpassing that of ibuprofen, a standard NSAID. Another compound, 3-hydroxy-3,3-diphenylpropanoic acid, shows activity matching that of ibuprofen, and is non-chiral and is proven to be non-toxic. The most of investigated compounds have interactions with P3 anchor site like COX-2 selective inhibitors. No tested substances or ibuprofen produced any significant gastric lesions.
History and current studies of petroarcheological data from the Neolithic and Eneolithic in Serbia
Vera Bogosavljevi?-Petrovi?,Jelena Markovi
Bulgarian e-Journal of Archaeology , 2012,
Abstract: The petrological identification of raw materials and their provenance has been carried out at only a small number of the Neolithic and Eneolithic sites in Serbia until the last three decades. Owing to the progress in the field of petroarchaeological investigation and the absence of uniformity in published works in recent years, the need for systematization appeared. The paper presents the history of research and a proposal for systematization the petroarchaeological database for Serbia.
Headspace Solid Phase Microextraction in Pesticide Residues Analysis:1. Optimisation of Extraction Conditions
Rada ?urovi?,Jelena Milinovi?,Mirjana Markovi,Dragan Markovi
Pesticidi i Fitomedicina , 2007,
Abstract: The method of headspace solid phase microextraction (HS/SPME) was successfully used in a simultaneous multicomponent analysis of hexachlorobenzene (HCB), tefluthrin, heptachlor, aldrin, chlorpyrifos, fenthion and bifenthrin in aqueous medium. Measurementswere performed using a nonpolar polydimethyl siloxane (PDMS) fiber. Detection and quantification were done by gas chromatography/mass spectrometry (GC/MS).Optimal conditions for HS/SPME were determined both by performing extraction at different temperatures and examining extraction time profiles at constant temperature. Optimal extraction temperature for each pesticide studied was determined as follows: 60°C for HCB and for heptachlor, 80°C for aldrin and for chlorpyrifos, fenthion and tefluthrin, and temperature exceeding 80°C for bifenthrin. For the pesticide mixture studied, 60°C was identified as the optimum extraction temperature.Based on the time profiles obtained, it was confirmed that satisfactory extraction sensitivity can be obtained even for extraction times shorter than the time required to reach a sorption equilibrium. This conclusion was confirmed by linear concentration profiles obtained for the following ranges: 0.05-10 ng/ml (HCB), 0.05-25 ng/ml (tefluthrin), 0.05-40 ng/ml (heptachlor), 0.05-40 ng/ml (aldrin), 0.05-25 ng/ml (chlorpyrifos), 0.05-25 ng/ml (fenthion)and 0.05-25 ng/ml (bifenthrin).Relative standard deviation (RSD) values for triplicate measurements did not exceed 15%.
Headspace Solid Phase Microextraction in Pesticide Residues Analysis: 2. Apple Samples
Rada ?urovi?,Jelena Milinovi?,Mirjana Markovi,Dragan Markovi
Pesticidi i Fitomedicina , 2007,
Abstract: Headspace solid phase microextraction method (HS/SPME), optimised previously for pesticide water solutions, was applied to trace residues of the pesticides chlorpyrifos, fenthion and bifenthrin in apple samples. One-hour extraction procedure was performed at 60oC extraction temperature. Nonpolar polydimethyl siloxane (PDMS) fiber was used. Detection and quantification were carried out by gas chromatography/mass spectrometry (GC/MS). A non-pesticide treated apple sample was fortified with the pesticides over a 0.025-1.25 mg/kg concentration range in order to determine analytical parameters of the method applied. Linearity with regression coefficient (R) values higher than 0.99 were obtained over the whole concentration range investigated for chlorpyrifos and fenthion, while linear dependence was observed in the 0.1-1.25 mg/kg range for bifenthrin. Relative recovery values for samples fortified at different levels were in the 56.68-82.91% range. Limit of detection (LOD) values were determined as follows: 0.014 mg/kg for chlorpyrifos, 0.021 mg/kg for fenthion and 0.053 mg/kg for bifenthrin. Relative standard deviation (RSD) values obtained for multiple analysis of the sample fortified at 0.6 mg/kg level were not higher than 20%.
Composition, structure and seasonal dynamics of macrozoobenthos in the Temska and Viso ica Rivers (Serbia)
?ivi? Ivana,Markovi? Z.,Ili? Jelena
Archives of Biological Sciences , 2005, DOI: 10.2298/abs0502107z
Abstract: We investigated macroozobenthos communities in the Temska and Viso ica Rivers at 10 localities during the summer and autumn of 2001. In 46 samplings of quantitative and 10 of qualitative analysis, 101 taxa from 17 groups of macrozoobenthos are identified. The most diverse group is the order Trichophtera (28 species from nine families). Less diverse with (only one species) are Nematomorpha, Hirudinea, Odonata, and Megaloptera. At all of the chosen localities, the most common species are Elmis aenea (70.00%), Ancylus fluviatilis, and Baetis sp. (60.00%). All those localities on the Viso ica and Temska Rivers are very similar. The index of similarity varies from 12.5% (between Vi0 and Te0) to 70.7% (between Te1 and Te2). In the Temska River the Shannon-Weaver diversity index varies from 1.80 (at Te3) to 2.45 (at Te0). In the Viso ica River, the highest diversity of macrozoobenthos is at the Vi3 locality (2.59), the lowest at Vi0 (1.40). Less diverse macrozoobenthos communities are found at the Vi0 and Te3 localities. At the same time, these localities have the highest values of Simpson's index (0.35 and 0.34, respectively).
Cyclic conjugation in benzo- and benzocyclobutadieno-annelated terrylenes and higher rylenes
Markovi? Marija,?ur?evi? Jelena,Gutman Ivan
Journal of the Serbian Chemical Society , 2012, DOI: 10.2298/jsc120131012m
Abstract: The effect of benzo- and benzocyclobutadieno-annelation on cyclic conjugation in terrylene and the higher members of the rylene homologous series is examined. Some peculiar regularities are established, that could not be observed in the case of perylene (the first member of the rylene series).
Late onset of severe thrombocytopenia during interferon treatment for chronic hepatitis C infection: Case report
Hajder Jelena,Stanisavljevi? Nata?a,Markovi? Olivera,Marisavljevi? Dragomir
Srpski Arhiv za Celokupno Lekarstvo , 2010, DOI: 10.2298/sarh1004240h
Abstract: Introduction. Thrombocytopenia is a common finding in chronic liver diseases and it is caused by different pathophysiological mechanisms. Immunologic thrombocytopenic purpura (ITP) in hepatitis C infection is a distinct clinical entity. Possible reasons for ITP in this case could be capabillity of HCV to induce autoimmune phenomena but also immunomodulatory effects of interferon that is used for HCV infection treatment. The specific laboratory parameters for ITP diagnosis during HCV infection have not been defined yet. Case Outline. A 37-year-old patient diagnosed with HCV infection was treated with PEG-interferon and Ribavirin during 24 weeks. The partial response was achieved after the therapy with reduction of viral replications. One month after therapy completion, the patient was hospitalized due to skin haemorrhagic syndrome and a serious degree of thrombocytopenia (2×109/l). The number and megakaryocyte morphology in bone marrow aspirate were normal. An assay of thrombocyte kinetics by radioactive marker (Indium 111) showed rapid thrombocyte destruction and their early seljuestration in the spleen. Conclusion. Results of assays about thrombocyte kinetics during HCV infection show enchanced thrombocyte destruction in the liver. Accordingly, the most important parameter for ITP diagnosis in HCV infection, in this case, was rapid thrombocyte destruction and their early sequestration in the spleen approved by Indium kinetics. Also, in support of ITP is the increment of thrombocyte number during therapy with intravenous immunoglobulins. Thrombocytopenia was developing during antiviral therapy and on indirect conclusion is that viral replication is not the reason for it.
Hormones of thyroid gland in sera of rats treated with different dose of concentrated potassium iodine solutions
Markovi? Ljiljana,Mihailovi?-Vu?ini? Violeta,Aritonovi? Jelena
Srpski Arhiv za Celokupno Lekarstvo , 2010, DOI: 10.2298/sarh1006323m
Abstract: Introduction Potassium iodine (KI) is used as a drug therapy for treating numerous diseases such as small-vessel vasculitis, erythema nodosum, vasculitis nodularis, Sweet's syndrome, tuberculosis and granulomatosis, and for iodized salt. At the same time, KI can be harmful. Iodine intake may increase the frequency of thyroiditis in humans, and may induce the occurrence of experimental thyroiditis (ET) in animals. Investigations on an experimental model for the examination of thyroiditis in Wistar rats have clearly showed morphological changes in the rat thyroid evoked by KI administration. Objective The purpose of this study was to compare the effects of low and high doses of KI on the thyroid gland of Wistar rats and determine the effect on hormone status (T4, T3 and TSH) in this rat strain. Methods Two groups of rats from the Wistar strain were treated with a low iodine dose (225 μg/g BW) and with a high iodine dose (675 μg/g BW) of KI solutions. Untreated nonimmunized animals served as controls. The solution was administrated daily intraperitoneally during the period of 26 consecutive days. Results Monitoring hormone status (TSH, T3 and T4) and morphological changes it was found that therapeutic doses of KI applied in treatment induced the occurrence of experimental thyroiditis (chronic destructive Hashimoto's thyroiditis in humans) and cell necrosis in animals not carrying a genetic susceptibility. Significant inflammatory changes were observed in rats treated with a high iodine dose. Conclusion The early iodine induced cell necrosis and inflammation in the nonimmunized animals without genetic susceptibility is a new experimental model of thyroiditis. .
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