Vol. 8 No. 1 (2018)

Open Access Original Scientific Paper

STATISTICAL ANALYSIS OF THE PRODUCTION OF BLUESTONE FROM GRANULATES (ELEMENTARY COPPER) BY OXIDATION WITH HYDROGEN PEROXIDE MIXED WITH STOCK SOLUTION OF BLUESTONE AND SULFURIC ACID

by Dragoslav Ilić

The technological process for the production of bluestone consists of three phases: the melting of waste copper in stationary flame furnaces, the granulate dissolution with sulfuric acid in the presence of the stock solvent of copper sulphate and hydrogen peroxide, and the crystallization of copper sulphate from a saturated blue stone solution in natural baths for crystallization. This paper describes the production of bluestone using hydrogen peroxide as an oxidation agent in a mixture of sulfuric acid and a stock solution of copper sulphate as well as the statistical description and graphic representation of the dissipation of copper Cu in (%), lead Pb in (%) and nickel Ni in (%) in the production of copper sulphate. On the basis of the statistical analysis, the value of copper Cu in (%) ranged from 70.3 to 99.78%, with an arithmetic mean of 91.88800%, which shows that the value of copper only in point 4 was below 80%.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-17822 Published: 30 Jun 2018

Open Access Original Scientific Paper

HOMOTOPY PERTURBATIONS METHOD: THEORETICAL ASPECTS & APPLICATIONS

by Vladica Stojanović, Tijana Kevkić

The application of the homotopy perturbation method (HPM) in two different research's area has been proposed in this paper. First, the HPM has been used for approximate solving of the well-known implicit equation for electrostatic surface potential of MOSFET transistor. The approximate analytical solution obtained in this case has relative simple mathematical form, and simultaneously high degree of accuracy. Next, HPM has been applied in determination of the invariant measures (IMs) of the non-linear dynamical systems with chaotic behavior. The convergence and efficiency of this method have been confirmed and illustrated in some characteristic examples of chaotic mappings.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-17290 Published: 30 Jun 2018

Open Access Original Scientific Paper

INFINITESIMAL BENDING OF CURVES ON THE RULED SURFACES

by Marija S Najdanović, Ljubica S Velimirović

In this paper we study infinitesimal bending of curves that lie on the ruled surfaces in Euclidean 3-dimensional space.We obtain an infinitesimal bending field under whose effect all bent curves remain on the same ruled surface as the initial curve. Specially, we consider infinitesimal bending of the curves which belong to the cylinder as well as to thehyperbolic paraboloid and find corresponding infinitesimal bending fields. We examine the variation of the curvature of a curve under infinitesimal bending on the hyperbolic paraboloid. Some examples are visualized using program packet Mathematica.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-17403 Published: 30 Jun 2018

Open Access Original Scientific Paper

CONTEMPORARY MIGRATORY MOVEMENTS IN THE MUNICIPALITY OF TRSTENIK

by Saša Milosavljević

Municipality of Trstenik located in spacious valley of Zapadna Morava, has always provided favorable conditions for the settlement of the population and the development of settlements. After the World War II, there was a need for recruiting a large number of people because of a huge development of metal industry in Trstenik, and that fact attract the immigrants from the area of Rasina, Aleksandrovačka Župa, Podibra, Lepenica, Levač and Temnić. The ratio between autochthonous and migrant population according to 1961 Census was 69%:31%, while the same ratio for the 2011 census was 59%:41%. Nearly a quarter (24%) of total number of immigrants immigrated in the inter-census period from 1981. to 1991, and almost all (94% of immigrants) immigrated from the same area of the republic. The process of emigration particularly intensified in the early nineties of the XX century when young and highly educated population emigrate, and the main reason for that was a poor economic situation.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-14183 Published: 27 Mar 2018

Open Access Original Scientific Paper

HUMIRON® IS AN EFFECTIVE BIODEGRADABLE SOURCE OF CHELATED IRON FOR PLANTS: AN IRON-59 UPTAKE STUDY

by Miroslav Nikolić

Here we tested plants’ ability to use iron (Fe) from the water-soluble commercial product Humiron® (a complex of Fe with highly purified and solubilized humic acids extracted from leonardite) as a source of chelated Fe for both strategy 1 (e.g. cucumber) and strategy 2 (e.g. barley) plant species grown under low Fe conditions. Iron from radioactive 59Fe-labelled Humiron® can easily be acquired by strategy 1 plant species via reduction of FeIII by the inducible plasma membrane-bound reductase, similarly to the reduction of synthetic FeIII-chelates. Strategy 2 plant species can also efficiently utilize Fe from Humiron® via ligand exchange between humates and phytosiderophores (PS). Moreover, the efficacy of Humiron® is comparable to Fe complexed with water-extractable humic substances obtained form peat. Being easily biodegradable this product can be used as an effective Fe source for organic crop production.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-16360 Published: 26 Mar 2018

Open Access Original Scientific Paper

KINETIC-CATALYTIC DETERMINATION OF ULTRAMICRO AMOUNTS OF Co(II) USING 4-HYDROXYCOUMARINE-PERMANGANATE REDOX REACTION

by Dragana Sejmanović, Ružica Micić, Ranko Simonović

Determination of Co(II) based on its catalytic effect on the reaction between 4-hydroxycoumarine and potassium permanganate, in the presence of acetate buffer was described. The method development includes optimization of the reagent concentration and temperature. Absorbance of potassium permanganate was measured at 525 nm. The calibration curve was linear in the range of 0.5 - 4 ng/cm3 of Co(II). The relative standard deviation was in the interval 6.25-2.60 % of the concentration range of 0.6-3 ng/cm3 Co(II), respectively. The interference effects of foreign ions were determined for the assessment of the selectivity of the method. The proposed method was found to have excellent sensitivity, relatively good selectivity and simplicity.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-16036 Published: 26 Mar 2018

Open Access Original Scientific Paper

SUPPLEMENT TO THE PHYTOGEOGRAPHICAL STUDIES OF THE RARE AND INTERNATIONALLY SIGNIFICANT SPECIES IN THE FLORA OF SERBIA, KOSOVO AND METOHIJA NORTH

by Danijela Prodanović, Zoran Krivošej, Miloš Stanojević, Slavica Ćirić

This paper reports the chorological data on 3 internationally significant floristic species in Serbia, in the Ibar river valley, Kosovo and Metohija North. Those are: Gladiolus palustris Gaudin, Himantoglossum caprinum (M. Bieb) Spreng. and Narcissus poeticus subsp. radiiflorus (Salisb.) Baker. It also reports new research findings on a rare species of vascular flora of Serbia - Phlomoides tuberosa (L.) Moench. The distribution of the mentioned species is shown in UTM 10 km X 10 km squares, based on the field researches, herbarium collections inspections and literature data. As the studied species belong to the group of internationally important and rare species, the familiarity with the status of their populations and degree of their vulnerability would present a good basis for monitoring their protection both in Serbia and Europe.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-15361 Published: 18 Dec 2017

Open Access Original Scientific Paper

CULTURAL-GEOGRAPHIC DETERMINANTS OF JERUSALEM

by Jovo Medojević

Culture and cultural phenomena are always in the focus of studying cultural geography. The study of Jerusalem from the aspect of supranational spread of culture is a special challenge. The cultural-geographical determinants of Jerusalem represent the features seen through the factors of time and space in which Jerusalem became and survived. The study of the morphology of cultural-geographical determinants in Jerusalem represents scientifically study of the relationship between man and his environment, the man's belief and application of perception of cultural-geographic determinants.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-15547 Published: 09 Dec 2017

Open Access Original Scientific Paper

THE SPRINGTAILS (INSECTA: COLLEMBOLA) FAUNA AT DIFFERENT MICROHABITATS OF BEČIĆI BEACH, MONTENEGRO

by Tatjana R Jakšić, Predrag S Vasić, Nenad Đ Labus, Olivera M Papović, Miloš R Stanojević, Nikola N Đukić

Collembola fauna has been investigated at different microhabitats near the beach in Bečići, Montenegro. Samples were collected from four locations: Hotel “Tara”, “Sveti Toma” Church (St. Thomas), Hotel “Naftagas” and “Zelena Stena” (Green Rock). Each of the location presented different microhabitat: under the palm tree, cypresses tree, larch tree and white pine tree. Samples were taken in May and September 2015 and results presented as qualitative findings. Total number of 30 Collembola species was identified, classified into six families and 17 genera. Representatives of the family Hypogastruridae and Isotomidae were recorded at all of the studied sites, while representatives of the families: Naenuridae, Onychiuridae, Entomobryidae and Sminthuridae were present on some of locations. The biggest number of species and the highest Collembola population density was found at the Green Stone site, 24 species in total, microhabitat- white pine, and the smallest number of species, 6 on site “St. Thomas” Church, microhabitat- cypresses trees.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-14774 Published: 02 Dec 2017

Open Access

TEMPORAL AND SPATIAL VARIATIONS OF AMBIENT DOSE EQUIVALENT RATE IN URBAN AND RURAL SITES

by Ljiljana Gulan

This study deals with the results of measuring the ambient dose equivalent rates conducted in test field. The impacts of temporal and weather variations (wind, precipitation, moisture, temperature) as well as spatial characteristics (rural and urban sites) on the ambient dose equivalent rate were analyzed. Mean ambient dose equivalent rate in rural site (142 nSv/h) is higher than in urban site (128 nSv/h). The reason is difference in altitude and also the difference in the local geology. Although an increasing of temperature, decreasing the moisture in air, and slowing down the wind speed during the observed period showed tendency of stability the ambient dose equivalent rate, no correlation was found between ambient dose equivalent rate and any parameter.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-16979

Open Access

INFLUENCE OF METEOROLOGICAL PARAMETERS ON THE OPERATION OF A GRID - CONNECTED PV SOLAR PLANT

by Dragana D Milosavljević

Elementary description and information on a grid-connected photovoltaic solar power plant (PV plant) of 2 kWp installed in Niš and the influence of meteorological parameters on its operation are given in this paper. Besides, experimental results of the calculation of the energy efficiency, electrical energy generated and output power of this PV plant operating in the real climate conditions in 2017 are presented. The results regarding climate parameters and characteristic performance parameter of 2 kWp PV plant in Niš in 2017 are discussed and it was found that in 2017 annual energy efficiency of this PV plant was 10.63% and it decreased with the ambient temperature increasing.

picture_as_pdf View Full-Text DOI 10.5937/univtho8-17271