Vol. 9 No. 1 (2019)

CAUSES AND CONSEQUENCES OF DEPOPULATION IN THE MUNICIPALITY OF KURŠUMLIJA

The municipality of Kuršumlija is located in the South of Serbia, encompassing the area of 952 km². According to the census from 2011, it is inhabited by 19,213 people. During the last decades, the municipality is facing the rapid decrease in the number of inhabitants, caused by natural and social factors. The manuscript analyzes the demographic changes reflected in the migration and structure of population in the period after 1948, along with the beginning of the industrial development, to 2011, when the municipality experienced the crash of economy. The analysis established that the municipality of Kuršumlija became emigrational area, especially after the closure of large industrial facilities which were the pillars of development. The young ones and those able for work were forced to leave their hearths, in search for employment and survival. All the settlements of Kuršumlija were included in the negative demographic processes reflected in the constant decrease of population. Big problem was also the intensity of inhabitants’ ageing, and lessening of the percentage of young ones, which points out that the municipality is in the phase of the deepest demographic age. The worrying fact is that the tendency of the population rate decrease in the settlements of Kuršumlija ‘municipality is prolonged.

ELEMENTS OF BIOCLIMATOLOGICAL CHARACTERISTICS OF VRANJSKA SPA

Bio-climatological analysis of Vranjska spa, based upon the equivalent temperatures (Teq) and Charles method (vapor weight), along with anthropo-climatic classification of Kruger, updated and adjusted, served as means of determining bio-climatological characteristics. Equivalent temperatures have been calculated for the period between 1985 and 2005, for the meteorological station Vranje, placed into six bio-climatological classes and three weather types. Representative weather types are cold (5.0 °C < Теq < 22.0 °C), agreeable (22.0 °C < Теq < 50.0 °C) and overheated (50.0 °C < Теq < 70.0 °C) with following classes: cold, algid, cool, agreeable, warm, humid and sultry.

MEDICINAL FLORA OF THE VIDLIČ MOUNTAIN IN SERBIA

A study of medicinal flora of the Vidlič mountain situated in southeastern Serbia was conducted. The presence of 264 plant species, that are considered official or used in folk medicine is recorded. An overview of medicinal plants is given in a systematic order. For each herb species, main medicinal substances which enter in its chemical composition are listed. An overview of plant parts which are curative and which families contain the highest numbers of medicinal species, are presented. A special review of species that contain toxic substances, as well as species that have become so rare in their natural habitats by irrational exploitation in nature that they have been declared protected and strictly protected taxa in the Republic of Serbia is given.

A CRITICAL REVIEW OF THE CURRENT CHECKLIST OF BUTTERFLIES OF SERBIA

The latest checklist of butterflies of Serbia (Papilionoidea Latreille, 1802) by Popović & Verovnik (2018) is examined. In consistencies with regard to the cited literature and applied systematics are pointed out. The validity of the viewpoints of the above mentioned authors on the species Leptidea juvernica Williams, 1946, Pyrgus trebevicensis (Warren, 1926), Erebia manto (Denis Schiffermüller, 1775) and Melitaea ornata Christoph, 1893 is discussed. It is shown that by imposing new Serbian names to butterflies disregards national and scientific heritage.

TRANSITION BETWEEN FLAT MAGNITUDE AND FLAT GROUP DELAY LOW PASS RECURSIVE DIGITAL FILTERS

Many a paper has been written on the characteristics of the continuous-time and discrete-time low-pass filters which are designed to have either maximally flat magnitude characteristics or maximally flat group delay responses. The polynomial (all pole) low pass recursive digital filters which are characterised by characterise the transition between a flat magnitude and flat group delay characteristics, named Transitional Butterworth Thiran (TBTh) recursive digital filters, is considered. The characteristics of the resulting filter change gradually from the characteristics of the well known Butterwort’s filter to the characteristics of the Thiran’s filter with the maximally flat group delay characteristic. Poles of the TBTh filter are obtained by interpolating between poles Butterworth and Thiran’s filters by varying a parametar which controls the pole positions that enables a tradeoff between the steepness magnitude characteristic at passband edge and group delay deviation.

BACTERIAL LOAD IN RELATION TO PHYSICO-CHEMICAL PARAMETERS AND FAECAL INDICATORS OF DRINKING WATER SOURCE

The aim of this study was to examine the relationship between bacterioplankton and physico-chemical parameters of water that serves as a source of drinking water as well as the relationship between bacterioplankton and the indicators of faecal contamination of water. Bacterioplankton abundance was determined by the cultivation method which included the inoculation of water samples on PCA and R2A media and incubation at 20 °C for 7 days. Total bacterial count was determined by epifluorescence microscopy, and three bacterial morphotypes were distinguished: rods, cocci and curved forms. Bacterial biomass was also determined. Eleven physico-chemical parameters of water were determined: temperature, pH, turbidity, conductivity, UV extinction, KMnO4 consumption, total phosphorus, orthophosphates, ammonium-, nitrite- and nitrate nitrogen. As indicators of faecal contamination, the counts of total coliforms, faecal coliforms, faecal streptococci and sulphite-reducing clostridia were determined. Although there were significantly higher number of bacteria on R2A medium in relation to PCA medium, both media showed significant negative correlation of aerobic mesophilic bacteria with water temperature, in all seasons, and significant positive correlation with UV extinction, turbidity, KMnO4 consumption, total phosphorus, orthophosphates, ammonium nitrogen and nitrate nitrogen. Also, these bacteria showed significant positive correlation with total bacterial count and bacterial biomass, as well as bacterial indicators of faecal contamination.

CHARACTERIZATION OF NEW SYNTHESIZED Fe2O3 NANOPARTICLES AND THEIR APPLICATION AS DETECTION SIGNAL AMPLIFIERS IN HERBICIDE BENTAZONE ELECTROANALYTICAL DETERMINATION

The iron oxide nanoparticles (Fe2O3 NPs) were synthesized from two different iron salts by solid-state synthesis method. The synthesized powder of Fe2O3 NPs is soluble in water, and the colloidal dispersion was characterized by TEM, FTIR, UV-Vis spectroscopy and zeta potential measurements. Obtained NPs are spherical in shape with narrow particle size distribution and an average diameter of 3 nm. Further, the possible application of Fe2O3 NPs was proposed, due to significant electroanalytical signal amplification in the determination of herbicide bentazone in natural river water.

COMPRESSION SET AND DAMPING PROPERTIES OF OIL-EXTENDED ELASTOMERS FOR SEALANTS PRODUCTION

NOVEL 4-FERROCENYL-8-(PHENYLTHIO)-1,2,3,4-TETRAHYDROQUINOLINE: DESIGN, SYNTHESIS AND SPECTRAL CHARACTERIZATION

Herein, we report design, synthesis and spectral characterization of novel 4-ferrocenyl-8-(phenylthio)-1,2,3,4-tetrahydroquinoline. Desired synthesis was achieved in three reaction steps, with a good overall yield (67%). First step included aza-Michael addition of 2-(phenylthio)aniline to 1-ferrocenylpropenone, subsequently, the obtained ketone was smoothly reduced to the corresponding 1,3-amino alcohol. The final step was an intramolecular cyclization prompted by acetic acid, proceeding via corresponding α-ferrocenyl carbocation. The synthesized compounds have been isolated pure, and their structure have been undoubtedly confirmed by standard spectral techniques (1H NMR, 13C NMR, IR and elemental analyses).

COMPARATIVE PERFORMANCE ANALYSIS OF SOME ACCELERATED AND HYBRID ACCELERATED GRADIENT MODELS

We analyze a performance profile of several accelerated and hybrid accelerated methods. All comparative methods are at least linearly convergent and have satisfied numerical characteristics regarding tested metrics: number of iterations, CPU time and number of function evaluations. Among the chosen set of methods we numerically show which one is the most efficient and the most effective. Therewith, we derived a conclusion about what type of method is more preferable to use considering analyzed metrics.

SOME NEW FIXED POINT RESULTS FOR CONVEX CONTRACTIONS IN B-METRIC SPACES

The purpose of this paper is to consider various results for convex contraction mappings in the context of B-metric spaces. We, among other things, generalize, extend, correct and enrich the recent published results from the context of convex contractions defined on an ordinary metric spaces to the ones on the so-called B-metric spaces. One example shows that this generalization is genuine. Let us note that this paper represents only the beginning of our investigation of the properties of convex contractions observed in any general metric space.

ASSESSMENT OF RADIATION RISK FROM DRINKING WATER AT PUBLIC FOUNTAINS ON THE WIDER TERRITORY OF KRUŠEVAC

Measurements of radon concentrations in drinking waters conducted on wider territory of the town of Kruševac included 16 public fountains, of which 4 are in the city itself and 12 in the surrounding area. Measurements of radon concentrations in water were carried out using radon detector RAD7 (DURRIDGE Co.). The values ​​of radon concentrations in water are in the range of (5.3 ± 0.8) Bq l-1 to (71.0 ± 7.2) Bq l-1 and are below the reference level of 100 Bq l-1, recommended by the European Commission. Since radon represents one of the most important causes of malignant diseases, annual effective doses of ingestion and inhalation are determined, whose mean values ​​are in the range of 0.04 mSv y-1 to 0.52 mSv y-1, and from 14.84 μSv y-1 to 198.8 μSv y-1, respectively. During sampling, water temperatures and their pH values were measured. These results are the first results of measuring radon in water in this area by this method. The aim of this paper is to evaluate whether there is, or not, a radiological risk to people's health due to the use of water primarily for drinking, but also for other purposes.