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Search Results: 1 - 10 of 119688 matches for " Kosti? Ivana T. "
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Electrostatic extrusion as a dispersion technique for encapsulation of cells and bioactive compounds
KostiIvana T.,Isailovi? Bojana D.,?or?evi? Verica B.,Levi? Steva M.
Hemijska Industrija , 2012, DOI: 10.2298/hemind111209013k
Abstract: Significant development of cells and bioactive compound encapsulation technologies is taking place due to an exceptional possibility of their application in various scientific disciplines, including biomedicine, pharmacy, cosmetology, food and agricultural sciences, beverage production, industrial waste treatment. Despite the broad application of microencapsulation, the literature reviews on dispersion techniques for microcapsule/microbead production, their advantages, restrictions and drawbacks are scarce. The purpose of this paper is to assess the possibilities of electrostatic extrusion for encapsulation of biological material, including living cells in hydrogel microbeads. The paper presents an overview of the mechanisms of droplet formation and controlling experimental parameters for producing microbeads by means of electrostatic extrusion. Electrostatic droplet formation utilizes a special type of physical process taking advantage of electrostatic effects occurring in flowing conductive liquids after introduction of an electric field.When an electrostatic field is applied to the metal needle and an electric charge is induced in the liquid flowing out of the needle, the size of droplet detaching from the needle tip decreases as a funcion of applied electrostatic field. It has been shown that few parameters affect microbead size: applied voltage, electrode geometry, needle size, polarity arrangement and polymer concentration. The electrostatic droplet formation is one of the most precise methods, which enables one to produce spherical and uniform particles ranging from 100 μm up to 1000 μm. Most of the authors report that the encapsulated compounds (drugs, enzymes and living cells) remain unaltered after electrostatic extrusion. This technique seems to be particularly promising in biotechnology, pharmaceutical and cosmetics industries, where a low-temperature process, preserving heat-sensitive material is a prerequisite. Future efforts in developing of electrostatic extrusion should be directed towards adequately scaling-up for commercial purpose.
Optimization of gradual hemolysis for isolation of hemoglobin from bovine erythrocytes
Pravilovi? Radoslava,Mojsilovi? Slavko,KostiIvana,Ili? Vesna
Hemijska Industrija , 2012, DOI: 10.2298/hemind111122008s
Abstract: In this work, we describe an optimized procedure based on gradual hemolysis for the isolation of hemoglobin derived from bovine slaughterhouse erythrocytes in a membrane bioreactor. The membrane bioreactor system provided high yields of hemoglobin (mainly oxyhemoglobin derivate) and its separation from the empty erythrocyte membranes (ghosts). Ten different concentrations of hypotonic media were assessed from the aspect of the extent of hemolysis, hematocrit values of the erythrocyte suspensions, cell swelling and membrane deformations induced by decreased salt concentration. Effective gradual osmotic hemolysis with an extent of hemolysis of 83% was performed using 35 mM Na-phosphate/NaCl buffer of pH 7.2-7.4. Under these conditions most of the cell membranes presented the appearance of the normal ghosts under phase contrast microscope. The results show that isolation process yielded predominantly to oxyhemoglobin. Kinetic studies showed that maximal concentration of hemoglobin was reached after 40 min, but the process cycle at which recovery of 83% was achieved lasted for 90 min.
Nela ?ivkovi?,Aleksandra Stankovi?,Ivana Krsti?,Tomislav Kosti
Acta Medica Medianae , 2009,
Abstract: Evaluating functional status in the patients with rheumatoid arthritis defines the presence of functional limitations and incapacitation. Patients’ ability to perform daily activities is reduced during the disease, and parameters influencing its reduction are numerous. The aim of this research was to examine the relation between joint damage and functional capacities of patients suffering from rheumatoid arthritis.The analysis included 98 patients with rheumatoid arthritis treated at the Institute Niska Banja . The examinees’ HAQ score was determined, after which they were separated into three functional groups, while standard hands and feet radiography determined the level of radiological damage (Larsen score). The majority of patients (41,8%) were characterized by functional disability (HAQ>2,01). The difference in values of Larsen score between the HAQ groups was statistically significant (p<0.001). There was no statistically significant association between the HAQ score and length of disease (p>0.05). The investigation showed that the increase of joint destruction reduces functional ability of patients with rheumatoid arthritis.
Gordana Bjelakovi?,Tatjana Jevtovi?,Gordana Kosti,Ivana Stojanovi?
Acta Medica Medianae , 2005,
Abstract: The osmotic fragility test of erythrocytes is useful in the diagnosis of different types of hereditary hemolytic anemias followed with hyperbilirubinemia. Hemolytic anemias, characterized by accelerated destruction of red blood cells, are usually the consequence of many metabolic abnormalities like cellular membrane defect, erythrocyte enzymes defect or hemoglobin abnormalities – hemoglobinopathies. The object of our study was to assess the relationship between osmotic fragility test of erythrocytes and severity of indirect hyperbilirubinemia in some inherited erythrocytes’ disorders. We did the osmotic fragility test of erythrocytes by using Dacie, s method with normal values of erythrocytes hemolysis between 0,48 to 0,34% NaCl (minimal to maximal hemolysis). In hereditary spherocytosis, fragility of erythrocytes was increased (min. at 0,50 % NaCl to max. 0,44 % NaCl) . In the child with β- thalassemia and cycle cell anemia erythrocytes fragility was decreased (min . at 0,42 to max. 0,32 % NaCl), that is 0,40% min. of hemolysis and 0,34% max. hemolysis in the second case. In newborn infants with high levels of indirect bilirubin in serum as a cause of physiological jaundice, the osmotic fragility test was within a normal range. Our findings point out the diagnostic value of osmotic fragility test in assessing patients with the indirect hyperbilirubinemia. This simple and important diagnostic test can be performed in small laboratories.
Copper(II) and lead(II) complexation by humic acid and humic-like ligands
Journal of the Serbian Chemical Society , 2011,
Abstract: The stability of metal–humate complexes is an important factor determining and predicting speciation, mobility and bioavailability of heavy metals in the environment. A comparative investigation of the complexation of Cu(II) and Pb(II) with humic acid and humic-like ligands, such as benzoic and salicylic acid, was performed. The analysis was realized at pH 4.0, a temperature of 25 °C and at an ionic strength of 0.01 mol dm-3 (NaCl) using the Schubert ion-exchange method and its modified form. The stability constants were calculated from the experimental data by the Schubert method for complexes with benzoic and humic acid. A modified Schubert method was used for the determination of the stability constants of the complexes with salicylic acid. It was found that Cu(II) and Pb(II) form mononuclear complexes with benzoic and humic acid while with salicylic acid both metals form polynuclear complexes. The results indicate that Pb(II) has a higher binding ability than Cu(II) to all the investigated ligands. The Cu(II)–salicylate and Pb(II)–salicylate complexes showed noticeable higher stability constants compared with their complexes with humic acid, while the stabilities of the complexes with benzoic acid differed less. Salicylic and benzoic acids as humic-like ligands can be used for setting the range of stability constants of humic complexes with Cu(II) and Pb(II).
T. Pavlovi?,Z. Pavlovi?,L. Panti?,Lj. Kosti
Contemporary Materials , 2010,
Abstract: Per-for-man-ce of pho-to-vol-ta-ic (PV) so-lar mo-du-le is af-fec-ted by its ori-en-ta-ti-on and its tilt an-gle with ho-ri-zon-tal pla-ne. The-se two pa-ra-me-ters chan-ge the amo-unt of so-lar energy re-ce-i-ved by the sur-fa-ce of the PV mo-du-le. In this ex-pe-ri-ment the ro-ta-ti-o-nal so-lar mo-du-le was po-si-ti-o-ned in the pre-de-fi-ned an-gles. The so-lar mo-du-le was ro-ta-ted to-wards the East, So-uth and West and po-si-ti-o-ned for the an-gles 00, 300, 450, 600 and 900. In the-se po-si-ti-ons the va-lu-es of cur-rent, vol-ta-ge, po-wer and so-lar ra-di-a-ti-on in-ten-sity we-re me-a-su-red. The op-ti-mum po-si-ti-ons we-re de-ter-mi-ned as po-si-ti-ons in which ma-xi-mum va-lu-es of so-lar in-ten-sity and ma-xi-mum po-wer we-re re-gi-ste-red. In this ex-pe-ri-ment the ef-fect of two-axis so-lar trac-king on elec-tri-cal energy ga-in was com-pa-red to the elec-tri-cal energy ga-in of a fi-xed PV mo-du-le. This study de-ter-mi-ned that PV mo-du-le ori-en-ted to-wards the So-uth gi-ves the gre-a-test va-lue of elec-tri-cal energy for the an-gle of 300, which is the ma-xi-mum re-gi-ste-red va-lue, so it re-pre-sents the op-ti-mum fi-xed po-si-ti-on for the PV mo-du-le in August. PV mo-du-le ro-ta-ted for the-se cho-sen an-gles for the sa-me day gi-ves 24.78% mo-re elec-tri-cal energy com-pa-red to the PV mo-du-le in op-ti-mal fi-xed po-si-ti-on, So-uth 300. In-cre-a-se in so-lar ra-di-a-ti-on of 28.76% re-sults in the in-cre-a-se in po-wer of 24.78%.
Complexity and asymptotic stability in the process of biochemical substance exchange in a coupled ring of cells
Dragutin T. Mihailovi?,Vladimir Kosti,Igor Bala?,Ljiljana Cvetkovi?
Mathematics , 2013, DOI: 10.1016/j.chaos.2014.04.008
Abstract: We have considered the complexity and asymptotic stability in the process of biochemical substance exchange in a coupled ring of cells. We have used coupled maps to model this process. It includes the coupling parameter, cell affinity and environmental factor as master parameters of the model. We have introduced: (i) the Kolmogorov complexity spectrum and (ii) the Kolmogorov complexity spectrum highest value to analyze the dynamics of two cell model. The asymptotic stability of this dynamical system using an eigenvalue-based method has been considered. Using these complexity measures we have noticed an 'island' of low complexity in the space of the master parameters for the weak coupling. We have explored how stability of the equilibrium of the biochemical substance exchange in a multi-cell system (N=100) is influenced by the changes in the master parameters of the model for the weak and strong coupling. We have found that in highly chaotic conditions there exists space of master parameters for which the process of biochemical substance exchange in a coupled ring of cells is stable.
Computing the Threshold of the Influence of Intercellular Nanotubes on Cell-to-Cell Communication Integrity
Dragutin T. Mihailovi?,Vladimir R. Kosti,Igor Bala?,Darko Kapor
Quantitative Biology , 2015,
Abstract: We examine the threshold of the influence of the tunneling nanotubes (TNTs) on the cell-to-cell communication integrity. A deterministic model is introduced with the Michaelis-Menten dynamics and the intercellular exchange of substance. The influence of TNTs are considered as a functional perturbation of the main communication and treated as the matrix nearness problems. We analyze communication integrity in terms of the \emph{pseudospectra} of the exchange, to find the \emph{distance to instability}. The threshold of TNTs influence is computed for Newman-Gastner and Erd\H{o}s-R\'enyi gap junction (GJ) networks.
Solar energy and sustainable development
Pavlovi? T.M.,Radosavljevi? J.M.,Pavlovi? Z.T.,Kosti? Lj.T.
Facta Universitatis Series : Physics, Chemistry and Technology , 2006, DOI: 10.2298/fupct0601113p
Abstract: In this paper attention is drawn to the energy consumption in the world solar energy, sustainable development, agenda 21 and the influence of the renewable energy sources and solar energy on the sustainable development.
Transitional justice and reconciliation in Bosnia-Herzegovina: Whose memories, whose justice?
Kosti? Roland
Sociologija , 2012, DOI: 10.2298/soc1204649k
Abstract: This paper shows that transitional justice initiatives such as the trials at the International Criminal Tribunal for the Former Yugoslavia and the State Court of Bosnia and Herzegovina, the Commission for Srebrenica and the establishment of accurate statistics on deaths during the conflict have had only a limited impact on inter-group reconciliation in Bosnia and Herzegovina. Popular attitudes towards these initiatives are captured in surveys conducted in 2005 and 2010. The results are not surprising given that the absence, due to the level of external regulation and control, of a politics of post-Dayton state-building means that domestic politics takes place in an arena of dealing with the past. The international community legitimised the three prevalent conflict narratives as a way of achieving a peace settlement in Dayton. These communal narratives were used in the peace-building phase by the local elites to defend concessions gained during negotiations and to oppose changes imposed by external supervisors of the Dayton Peace Accords. This has transformed the debate over the recent conflict from a transitional process of coming to terms with the past to a permanent state of affairs. This process precludes reconciliation in terms of mutual acknowledgment of suffering and a nuanced understanding of the causes and dynamics of the violent conflict.
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