Facta Universitatis - Series: Physics, Chemistry and Technology最新文献

{"title":"PRODUCTION OF NIGERICIN AND NIPHIMYCIN BY SOIL ISOLATE STREPTOMYCES SP. MS1: ANTI-CANDIDA BIOASSAY GUIDED RESPONSE SURFACE METHODOLOGY FOR THE OPTIMIZED CULTURE MEDIUМ","authors":"Marija Mojicevic, J. Grahovac, M. Petkovic, I. Vučković, J. Dodić, S. Dodić, S. Vojnovic","doi":"10.2298/fupct1701001m","DOIUrl":"https://doi.org/10.2298/fupct1701001m","url":null,"abstract":"Anti-Candida bioassay guided optimization of the culture medium was used in order to enhance the antifungal activity of the soil isolate MS1. Its morphological, physiological and biochemical characteristics, as well as 16S rDNA sequencing, assigned an MS1 isolate to genus Streptomyces. Optimization of the culture medium was achieved by experimental factorial design and response surface methodology. Maximal antifungal components production was obtained with starch, soybean meal and phosphates content of 40.52, 5.10 and 2.21 g/L, respectively. Chromatography and 1H and 13CNMR spectroscopy were employed for purification and structural characterization of antifungal antibiotics concurrently produced by this strain. These antibiotics were identified as polyether carboxylic antibiotic nigericin and guanidyl-polyol macrolide, niphimycin.","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"38 1","pages":"001-016"},"PeriodicalIF":0.0,"publicationDate":"2017-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85997318","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"STUDY OF LITHIUM ALUMINIUM HYDRIDE REDUCTION OF 5-ACETYL-1,6-DIMETHYL-4-PHENYL-3,4-DIHYDROPYRIMIDIN-2(1H)-ONE","authors":"B. Zlatković, S. Radulović","doi":"10.2298/FUPCT1701017Z","DOIUrl":"https://doi.org/10.2298/FUPCT1701017Z","url":null,"abstract":"In this paper, we investigated the LiAlH 4 -reduction of 5-acetyl-1,6-dimethyl-4-phenyl-3,4-dihydropyrimidin-2(1H)-one (N-methylated Biginelli compound). Following the reduction and SiO 2 -promoted dehydration, (Z)-5-ethylidene-1-methyl-6-methylene-4-phenyltetrahydropyrimidin-2(1H)-one was isolated as the major product (33% yield). Chromatographic separation of the reaction products also allowed us to isolate (yield in parentheses) and fully spectrally characterize: 1,6-dimethyl-4-phenyl-5-vinyl-3,4-dihydropyrimidin-2(1H)-one (20%), 5-ethyl-1,6-dimethyl-4-phenyl-3,4-dihydro-pyrimidin-2(1H)-one (9%), 5-(1-hydroxyethyl)-1,6-dimethyl-4-phenyl-3,4-dihydropyrimidin-2(1H)-one (5%). A possible mechanism explaining the formation of these products is proposed.","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"48 1","pages":"017-022"},"PeriodicalIF":0.0,"publicationDate":"2017-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73928330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BERYLLIUM-7 SURFACE CONCENTRATION EXTREMES IN EUROPE","authors":"J. Ajtić, D. Sarvan, V. Djurdjević, M. Hernández-Ceballos, E. Brattich","doi":"10.2298/FUPCT1701045A","DOIUrl":"https://doi.org/10.2298/FUPCT1701045A","url":null,"abstract":"Seasonal and spatial patterns of extremely high beryllium-7 surface concentration recorded over the 2001–2010 period across Europe are investigated. The beryllium-7 measurements for 14 sites are taken from the Radioactivity Environmental Monitoring Database. The maxima and minima in the annual cycle of the beryllium-7 surface concentration occur later in the year as the latitude of the measurement site decreases. Extremely high beryllium-7 surface concentrations are defined here as values greater than the 95 th percentile in each measurement site. Most of the extremes occur over the March–August period. At least 10 % of the total number of extremes appear during autumn and winter, with an exception of Vienna, where all the extremes took place during spring and summer. The regional spread of extremes common to pairs of measurement sites points to an existence of three distinct regions in Europe: north of 55 °N, between 45 °N and 55 °N, and south of 45 °N. Although the beryllium-7 concentration records are significantly correlated across all the investigated sites, the strongest correlations are found within the identified regions.","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"36 1 1","pages":"45-55"},"PeriodicalIF":0.0,"publicationDate":"2017-12-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72944953","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"VOLTAGE DEPENDENT MODELS OF THE FORMATIVE TIME DELAY IN ARGON","authors":"S. Stamenković, V. Marković, A. Jovanović, M. Stankov","doi":"10.2298/FUPCT1702081S","DOIUrl":"https://doi.org/10.2298/FUPCT1702081S","url":null,"abstract":"Measurements of the formative time delay t_f  at different working voltages U in argon at low pressure are presented. The well-known decreasing voltage behavior of the formative time delay is theoretical described by different empirical and semiempirical models. In addition to introduced empirical models, some models from the literature are applied to elucidate experimentally obtained t_f(U) dependence. However, the models from the literature show a good agreement with the experimental data only at low overvoltages DeltaU (DeltaU=U-U_s where U_s is the static breakdown voltage).  Therefore, empirical corrections are made based on data analysis, and good compatibility is achieved in a whole range of working voltages. HIGHLIGHTS Presentation of the formative time delay measurements at different working voltages in argon at low pressure Application of empirical and semi-empirical models for description of t_f(U) dependence Application of the t_f(U) models from the literature with and without empirical corrections","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"3 1","pages":"081-093"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81134681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"INVESTIGATION OF THE ENERGY EFFICIENCY OF HORIZONTALLY MOUNTED SOLAR MODULE SOILED WITH CaCO3","authors":"I. Radonjić, T. Pavlovic","doi":"10.2298/FUPCT1702057R","DOIUrl":"https://doi.org/10.2298/FUPCT1702057R","url":null,"abstract":"Soiling is a term used to describe the deposition of dust (dirt) on solar modules, which reduces the amount of solar radiation reaching the solar cells. Deposition of dust on solar modules can make the operation of the entire PV system - more difficult and, therefore, lead to the generation of less electric energy. Soiling of solar modules also influences solar modules parameters ( short-circuit current , open-circuit voltage , maximum power, fill factor and efficiency ). This paper presents the results of the investigation on the impact different quantities of calcium carbonate (CaCO 3 ) deposition have on the energy efficiency of horizontally mounted solar modules. The s hort-circuit current, power and efficiency decrease with increasing the mass of CaCO 3 deposited on the horizontally mounted solar module. The open-circuit voltage and fill factor very slightly increase with increasing the mass of CaCO 3 deposited on the horizontally mounted solar module. Upon soiling with 1 g of calcium carbonate, the solar module efficiency decreased by 4.6% in relation to the clean solar module , upon soiling with 2 g of calcium carbonate it decreased by 6.0%, and upon soiling with 3 g of calcium carbonate it decreased by 12.9% in relation to the clean solar module. It can be concluded that the power and energy efficiency of the solar module decrease due to the increased amount of calcium carbonate. HIGHLIGHTS Short-circuit current decreases with increasing mass of CaCO 3 deposited on the horizontally mounted solar module, which is in line with the fact that the short-circuit current is proportional to the intensity of solar radiation incident. Open-circuit voltage very slightly increases with increasing mass of CaCO 3  deposited on the horizontally mounted solar module, which is in line with the fact that U oc is almost constant with a change in the intensity of solar radiation. The power obtained by a horizontally mounted solar module decreases with increasing mass of CaCO 3 on its surface. Fill factor slightly increases with increasing mass of CaCO 3 deposited on the horizontally mounted solar module. The efficiency of the horizontally mounted solar module decreases with increasing amount of CaCO 3 deposited on its surface.","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"143 1","pages":"057-069"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76215890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"VOLATILE GLUCOSINOLATE BREAKDOWN PRODUCTS AND THE ESSENTIAL OIL OF DESCURAINIA SOPHIA (L.) WEBB EX PRANTL (BRASSICACEAE)","authors":"M. Dekić, N. Radulović, Jelena B. Danilović-Luković, D. Stojanović","doi":"10.2298/FUPCT1702095D","DOIUrl":"https://doi.org/10.2298/FUPCT1702095D","url":null,"abstract":"Volatile constituents obtained by autolysis of aerial and underground parts of D. sophia and the essential oil obtained by hydrodistillation of whole plant samples were analyzed in detail by GC and GC-MS. In total, 71 constituents were identified, accounting for more than 90% of the total peak areas in the chromatograms. Both aerial and underground autolysates contained considerable amounts of lignan arctigenin and cuticular wax compounds. The essential oil was dominated by glucosinolate breakdown product 4-pentenenitrile. Glucosinolate degradation products identified in the essential oil and autolysates, 3-butenyl isothiocyanate, 4-pentenenitrile and allyl isothiocyanate, suggested the presence of gluconapin and sinigrin in this species as the most likely “mustard oil” precursors. HIGHLIGHTS Volatile constituents of Descurainia sophia essential oil and autolysates were analyzed in detail by GC and GC-MS. The analyses allowed the identification of 71 compounds in total. Descurainia sophia contains glucosinolates gluconapin and sinigrin and lignan arctigenin.","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"31 1","pages":"095-102"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75540505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"THE FIRST AND SECOND MOMENTS FOR THE QUANTUM BROWNIAN PLANAR ROTATOR IN EXTERNAL HARMONIC CLASSICAL FIELD","authors":"I. Petrović, J. Jeknić-Dugić","doi":"10.2298/FUPCT1702071P","DOIUrl":"https://doi.org/10.2298/FUPCT1702071P","url":null,"abstract":"We derive explicit expressions for the first and second moments as well as the correlation function for a planar (one-dimensional) quantum Brownian rotator placed in the external harmonic potential. Our results directly provide the standard deviations for the azimuthal angle and the canonically conjugate angular momentum for the rotator. We find that there are some significant physical differences between this model and the free rotator model, which is well investigated in the literature. HIGHLIGHTS Expressions were derived for the first and second moments, and the correlation function for a planar (one-dimensional) quantum Brownian rotator placed in the external harmonic potential. In comparison with the well-known free Brownian rotator, we observe the existence of the stationary state in the asymptotic limit (). Significantly smaller standard deviations and the correlation-function for the rotator exerted to the external harmonic potential we established.","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"3 1","pages":"071-079"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88240711","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"BLEND OF NATURAL WAXES AS A MATRIX FOR AROMA ENCAPSULATION","authors":"Jelena Milanović, Gordana Ilić Sević, M. Gavrilović, M. Milosavljević, B. Bugarski","doi":"10.2298/fupct1702103m","DOIUrl":"https://doi.org/10.2298/fupct1702103m","url":null,"abstract":"In this study, the possibility of using a blend of natural waxes (bees and carnauba) for encapsulation of some aroma compounds was investigated. Melt dispersion/melt solidification technique was applied for microbeads production. Since one of the most important characteristics of the particles are the size and shape, particle size distribution as well as morphological properties are tested. Thermal characteristics are also examined as significant properties for thermal behavior at elevated temperatures, important for application of encapsulated particles in food production processes. Different contents of the carnauba wax in the mixture with beeswax are investigated, from 10% to 50% (w/w). Since one of the potential applications of the encapsulated aroma is in feed additives production, the targeted particle size range was under 300 μm to be suitable for handling and mixing with other powder substances. According to the obtained results, a higher carnauba wax content in the wax blend had an impact on particle size distribution. Also, it had an impact on the surface morphology and thermal properties. The obtained results may contribute to the development of methods of encapsulation of hydrophobic aromas in the natural wax matrix HIGHLIGHTS Blend of natural waxes is investigated as a potential matrix for aroma encapsulation Target particle size is reached with blend ratio 50:50 (bees :carnauba) Blend of beeswax and carnauba wax is a promising carrier for aroma encapulation","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"21 1","pages":"103-111"},"PeriodicalIF":0.0,"publicationDate":"2017-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78153707","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"QUALITY CONTROL IN RADIATION PROCESSING IN THE VINČA INSTITUTE RADIATION PLANT- CASE STUDY","authors":"B. Šećerov, Danijela Stancov, M. Radenković, M. Dramićanin","doi":"10.2298/FUPCT1602105S","DOIUrl":"https://doi.org/10.2298/FUPCT1602105S","url":null,"abstract":"The irradiation process control has to define facility parameters, validation of product and routine control of the irradiation process during exploitation. To meet the regulations, it is necessary to stop the exploitation and do the qualification exercises after changes in the source loading, source geometry or product transport system. In order to save time, the new combined approach has been analyzed for qualification of sterilization process used in the Vinca Institute Radiation Plant. The absorbed dose is calculated assuming that the irradiation process runs with specified parameters. The results of absorbed dose measurements in an experiment done during the sterilization process were used for dose calculations. The calculated absorbed doses are compared with measured ones. The criterion for a positive qualification is the superposition of calculated and measured values. Two different types of dosimeters are used for measurements: ethanolchlorobenzene and alanine. The measurement traceability is achieved through the calibration by the Riso National Laboratory, Denmark. In this case study, the determined dwell time for target dose is 450s. 1.23 is dose uniformity ratio in the box with plastic products with dose minimum at the bottom corners in the center and dose maximum at the top of the surface plane of the box parallel to the source. The calculated and measured absorbed doses show the same difference of 13% between the surface and the central plane in the box. The dose reproducibility for irradiation process is 3.5%.","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"3 1","pages":"105-113"},"PeriodicalIF":0.0,"publicationDate":"2016-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78602907","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"KANTOWSKI-SACHS MINISUPERSPACE COSMOLOGICAL MODEL ON NONCOMMUTATIVE SPACE","authors":"Darko Radovancevic, L. Nešić","doi":"10.2298/FUPCT1601021R","DOIUrl":"https://doi.org/10.2298/FUPCT1601021R","url":null,"abstract":"A vacuum homogeneous and anisotropic Kantowski-Sachs minisuperspace cosmological model is considered. In a classical case, Lagrangian of the model is reduced by a suitable coordinate transformation to Lagrangian of two decoupled oscillators with the same frequencies and with zero energy in total (an oscillator-ghostoscillator system). The model is formulated also on noncommutative space.","PeriodicalId":12248,"journal":{"name":"Facta Universitatis - Series: Physics, Chemistry and Technology","volume":"28 1","pages":"21-26"},"PeriodicalIF":0.0,"publicationDate":"2016-11-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91419749","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}