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Dive into the research topics where Jasmina Jovanovic is active.

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Featured researches published by Jasmina Jovanovic.


Plasma Sources Science and Technology | 2007

Kinetic phenomena in charged particle transport in gases, swarm parameters and cross section data*

Z. Lj. Petrović; Milovan Suvakov; Ž. Nikitović; S. Dujko; Olivera Šašić; Jasmina Jovanovic; Gordana Malović; Vladimir M. Stojanovic

In this review we discuss the current status of the physics of charged particle swarms, mainly electrons. The whole field is analysed mainly through its relationship to plasma modelling and illustrated by some recent examples developed mainly by our group. The measurements of the swarm coefficients and the availability of the data are briefly discussed. More time is devoted to the development of complete electron?molecule cross section sets along with recent examples such as NO, CF4 and HBr. We extend the discussion to the availability of ion and fast neutral data and how swarm experiments may serve to provide new data. As a point where new insight into the kinetics of charge particle transport is provided, the role of kinetic phenomena is discussed and recent examples are listed. We focus here on giving two examples on how non-conservative processes make dramatic effects in transport, the negative absolute mobility and the negative differential conductivity for positrons in argon. Finally we discuss the applicability of swarm data in plasma modelling and the relationship to other fields where swarm experiments and analysis make significant contributions.


Journal of Physics D | 1995

On spatial distribution of optical emission in radio frequency discharges

Z. Lj. Petrović; Svetlan Bzenić; Jasmina Jovanovic; S Djurovic

In this paper we present calculations of the spatial distributions of emission in model argon discharges which correspond to the conditions of argon discharges in the GEC rf reference cell but are relevant for other similar rf discharges. The calculations on the basis of the particle in cell (PIC) code show that transitions with high threshold energy are predominantly excited by secondary electrons originating from the instantaneous cathode while the transitions with lower threshold energy are excited predominantly by electrons accelerated by sheath motion. In addition it is shown that the spatial distribution of 811 nm radiation of argon corresponds best to excitation by very low-energy electrons from the metastable state. The different kinetics of excitation of the three groups of transitions mentioned above, in conjunction with different energy dependences of the cross sections and special conditions when there is a significant if not dominant contribution of the gamma process in sustaining the discharge, give rise to the different spatial distributions of emission which are opposed to the intuitively expected distributions and raise questions about the applications of spatial distributions of emission in determining the sheath width and in diagnostic techniques such as actinometry.


Diamond and Related Materials | 1995

The influence of excited states on the kinetics of excitation and dissociation in gas mixtures containing methane

A. Jelenak; Jasmina Jovanovic; Svetlan Bzenić; S. B. Vrhovac; S.S. Manola; B. Tomčik; Z. Lj. Petrović

Abstract In this paper, we extend the calculations for rare gas discharges, which aim to establish the influence of excited states on the kinetics of electron-induced excitation, to rare gas-methane mixtures and pure methane which are often used in diamond-like film deposition. In particular, we address the effect of non-thermal vibrational populations on the rate coefficients in methane-containing gas discharges using the procedure applied previously for pure silane. Furthermore, we investigate the kinetics of electronically excited levels of rare gases and methane in the presence of a significant population of excited states. These states may contribute to the overall ionization, excitation and dissociation rates through stepwise processes, superelastic collisions and energy transfer processes. The influence of superelastic processes on the development of the negative differential conductivity (NDC) is discussed on the basis of the momentum transfer theory, and it is shown that the NDC is reduced when significant populations of excited states are present. This is of importance for calculations of the transport coefficients for a.c. electric fields where NDC leads to a complex temporal dependence of the drift velocity and thus directly affects the power deposition in the discharge. Finally, we present the rate and transport coefficients calculated for methane in r.f. fields based on the Monte Carlo simulation for time-dependent fields. A good agreement with the effective field approximation and earlier Boltzmann calculations is found.


Plasma Sources Science and Technology | 2010

Measurements and analysis of electron transport coefficients obtained by a pulsed Townsend technique

Olivera Šašić; J. de Urquijo; A M Juárez; Snježana Dupljanin; Jasmina Jovanovic; J L Hernández-Ávila; Eduardo Basurto; Z. Lj. Petrović

A review of a wide range of electron swarm studies in several pure gases and gas mixtures is given. These studies include the determination of the cross section set for electrons in C2H2F2 (R134a) based on recent measurements of transport data, the re-analysis of the cross sections for electrons in N2O and its mixtures with N2 and SF6 and, finally, the analysis of electron transport in N2–Ar and Xe–He mixtures. It was found that in the case of R134a further studies of the characteristic energy are needed for its mixtures with argon in pure gases in order to obtain a reliable set of cross sections. For N2O, a set has been developed that fits a wide range of data. However, some verification of significant changes in the shape of the attachment cross section should still be done. In two different sets of data for the mixtures of Xe and He and of Ar and N2, the existing cross sections do a very good job throughout most of the energy range, although some small adjustments may be sought at the higher end of the relevant energy range for xenon. In this paper we summarize the work already described in separate papers for each of the He–Xe and Ar–N2 mixtures, and we present here a number of transport coefficients and analyses that were not included in the original papers.


Australian Journal of Physics | 1997

Influence of excited molecules on electron swarm transport coefficients and gas discharge kinetics

Zoran Petrović; Jasmina Jovanovic; Zoran Raspopovic; Svetlan Bzenić; S. B. Vrhovac

In this paper we study different effects of excited molecules on swarm parameters, electron energy distribution functions and gas discharge modeling. First we discuss a possible experiment in parahydrogen to resolve the discrepancy in hydrogen vibrational excitation cross section data. Negative differential conductivity (NDC) is a kinetic phenomenon which manifests itself in a particular dependence of the drift velocity on E/N and it is affected by superelastic collisions with excited states. A complete kinetic scheme for argon required to model excited state densities in gas discharges is also described. These results are used to explain experiments in capacitively and inductively coupled RF plasmas used for processing. The paper illustrates the application of atomic and molecular collision data, swarm data and the theoretical techniques in modeling of gas discharges with large abundances of excited molecules. It is pointed out that swarm experiments with excited molecules are lacking and that there is a shortage of reliable data, while the numerical procedures are sufficiently developed to include all the important effects.


Plasma Sources Science and Technology | 2013

Ion mobilities and transport cross sections of daughter negative ions in N2O and N2O–N2 mixtures

J. de Urquijo; Jasmina Jovanovic; A Bekstein; Vladimir Stojanovic; Z. Lj. Petrović

A pulsed Townsend apparatus is used to measure the mobility of a single negative ion species in N2O and N2O?N2 gas mixtures. The range of the density-normalized electric field, E/N, is 6.5?100?Td (1 Townsend?=?10?17?V?cm2) over the pressure range 10?250?Torr and temperature range 295?300?K. Based on previous work it is shown that the most likely drifting ion is . A reaction scheme involving ion conversion and electron detachment is presented, ending with the formation of a stable ion. The momentum transfer integral cross section for in pure N2O and N2 gases is derived from the above measurements. The unfolded cross sections are used as an initial guess and then further improved by ensuring good agreement between Monte Carlo calculated mobilities and the experimental results for the N2O?N2 mixture.


Journal of Physics D | 2009

Electron impact ionization and transport in nitrogen?argon mixtures

Jasmina Jovanovic; Eduardo Basurto; Olivera Šašić; J L Hernández-Ávila; Z. Lj. Petrović; J. de Urquijo

The electron drift velocities and ionization coefficients in the nitrogen–argon mixtures have been measured and calculated over a wide range of E/N and mixture concentrations. It was found that standard cross section sets for low and moderate energies fit the transport data very well. Derived quantities such as the mean energy for electrons and the ratio between the transverse diffusion coefficients and the electron mobility have also been calculated.


Journal of Physics: Conference Series | 2009

Cross sections and transport properties of negative ions in rare gases

Jasmina Jovanovic; Z. Lj. Petrović

We have used a combination of a simple semi-analytic theory - Momentum Transfer Theory (MTT) and exact Monte Carlo (MC) simulations to develop momentum transfer cross sections of negative ions in collisions with noble gases based on the available data for reduced mobility at 300K as a function of E/N. At very low energies, we extrapolated obtained cross sections using Langevins cross section and supplemented it by the total detachment cross section that was used from the threshold around 6 eV up to 100 eV. Other possible reactive processes have not been taken into account. A good agreement for the mean energy and diffusion coefficients is an independent proof of the validity of the cross sections that were derived for the negative ion mobility data.


Journal of Physics: Conference Series | 2014

Mobility of positive ions in CF4

Vladimir Stojanovic; Zoran Raspopovic; Jasmina Jovanovic; J. de Urquijo; Z. Lj. Petrović

Cross-section sets for transport of positive ions in CF4 that fit the available experimental data for mobility are assessed by normalizing the available experimental and theoretical cross-sections within the framework of the swarm method. Transport parameters for positive ions in CF4 in DC fields at a gas temperature of T = 300 K are calculated as a function of the reduced electric fields E/N (N being the gas density) by using Monte Carlo simulation.


Upsala Journal of Medical Sciences | 2018

MicroRNA meta-signature of oral cancer: evidence from a meta-analysis

Katarina Zeljic; Ivan Jovanovic; Jasmina Jovanovic; Zvonko Magic; Aleksandra Stanković; Gordana Supic

Abstract Aim: It was the aim of the study to identify commonly deregulated miRNAs in oral cancer patients by performing a meta-analysis of previously published miRNA expression profiles in cancer and matched normal non-cancerous tissue in such patients. Material and methods: Meta-analysis included seven independent studies analyzed by a vote-counting method followed by bioinformatic enrichment analysis. Results: Amongst seven independent studies included in the meta-analysis, 20 miRNAs were found to be deregulated in oral cancer when compared with non-cancerous tissue. Eleven miRNAs were consistently up-regulated in three or more studies (miR-21-5p, miR-31-5p, miR-135b-5p, miR-31-3p, miR-93-5p, miR-34b-5p, miR-424-5p, miR-18a-5p, miR-455-3p, miR-450a-5p, miR-21-3p), and nine were down-regulated (miR-139-5p, miR-30a-3p, miR-376c-3p, miR-885-5p, miR-375, miR-486-5p, miR-411-5p, miR-133a-3p, miR-30a-5p). The meta-signature of identified miRNAs was functionally characterized by KEGG enrichment analysis. Twenty-four KEGG pathways were significantly enriched, and TGF-beta signaling was the most enriched signaling pathway. The highest number of meta-signature miRNAs was involved in the sphingolipid signaling pathway. Natural killer cell-mediated cytotoxicity was the pathway with most genes regulated by identified miRNAs. The rest of the enriched pathways in our miRNA list describe different malignancies and signaling. Conclusions: The identified miRNA meta-signature might be considered as a potential battery of biomarkers when distinguishing oral cancer tissue from normal, non-cancerous tissue. Further mechanistic studies are warranted in order to confirm and fully elucidate the role of deregulated miRNAs in oral cancer.

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J. de Urquijo

National Autonomous University of Mexico

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