Exploring the bulk of the BL Lac object population:1. parsec-scale radio structures

Context. The advent of Fermi is changing our understanding on the radio and gamma-ray emission in Active Galactic Nuclei. Contrary to pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the gamma-ray band. However, since they are relatively weak radio sources, most of their parsec-scale structure and their multi-frequency properties are poorly understood and/or have not been investigated in a systematically fashion. Aims. Our main goal is to analyze the radio and gamma-ray emission properties of a sample of 42 BL Lacs selected, for the first time in the literature, with no constraint on their radio and gamma-ray flux densities/emission. Methods. Thanks to new Very Long Baseline Array observations at 8 and 15 GHz for the whole sample, we present here fundamental parameters such as radio flux densities, spectral index information, and parsec-scale structure. Moreover, we search for gamma-ray counterparts using data reported in the Second Catalog of Fermi Gamma-ray sources. Results. Parsec-scale radio emission is observed in the majority of the sources at both frequencies. Gamma-ray counterparts are found for 14/42 sources. Conclusions. The comparison between our results in radio and gamma-ray bands points out the presence of a large number of faint BL Lacs showing "non classical" properties such as low source compactness, core dominance, no gamma-ray emission and steep radio spectral indexes. A deeper multiwavelength analysis will be needed.Comment: 19 pages, 6 figures, 6 tables, accepted for publication in A&

Correlation of structure and chromatographic behavior of the polioxygenated steroids by the means of thin-layer chromatography

U okviru ove doktorske disertacije detaljno je proučavan uticaj supstituenata vezanih za A prsten na hromatografsko ponašanje serije polioksigenovanih steroida u uslovima tankoslojne hromatografije. U cilju proučavanja uticaja polarnosti sorbenta na retenciju ispitivanih jedinjenja upotrebljena su dva veoma različita sorbenta: polarni nemodifikovani silika-gel i nepolarni C-18 modifikovani silika-gel. Posebna pažnja posvećena je razmatranju uticaja sastava primenjenih mobilnih faza na retenciju radi što boljeg razumevanja odnosa hromatografskog ponašanja i lipofilnosti ispitivanih jedinjenja. Uzimajući u obzir svojstva sorbenta kao i korišćenih mobilnih faza, retenciono ponašanje je izučavano u uslovima normalno-fazne i reverzno-fazne hromatografije. Kao tipični normalnofazni sistemi upotrebljeni su polarni silika-gel kao stacionarna faza i manje polarni rastvarači (aceton, heksan, acetonitril, dihlormetan) kao mobilna faza. Reverzno-fazni sistemi sastojali su se od smeše voda ˗ organski rastvarač (aceton, metanol ili acetonitril) i oktadecil modifikovanog silika-gela kao stacionarne faze. U uslovima normalno-fazne hromatografije sistem aceton/nheksan se pokazao kao pogodan za ispitivanje uticaja sastava mobilne faze na hromatografsko ponašanje polioksigenovanih steroidnih jedinjenja. U uslovima reverzno-fazne hromatografije najbolja selektivnost je postignuta primenom mobilne faze metanol - voda. U okviru ovog rada proučena je i mogućnost primene tankoslojne hromatografije za brzo i jednostavno određivanje lipofilnosti kao važnog parametra biološke aktivnosti ispitivanih steroida. Utvrđeno je da postoji linearna zavisnost između retencionih parametara ispitivanih jedinjenja i sastava dvokomponetnih mobilnih faza. Ispitivanjem korelacije između hromatografski određenih parametara lipofilnosti i teorijski izračunatih logP vrednosti utvrđeno je da je reverzno-fazna hromatografija pogodnija za procenu lipofilnosti ispitivanih jedinjenja.Takođe pokazano je da ispitivani polioksigenovani steroidi sa supstituisanim A prstenom predstavljaju kongenernu seriju. Primenom višestruke linearne regresije (multiple linear regression, MLR) i metode parcijalne regresije najmanjih kvadrata (partial least squares, PLS) proučavane su moguće zavisnosti između hromatografskog ponašanja i molekulskih svojstava analita. Na osnovu statističkih parametara dobijenih za tri reverzno-fazna hromatografska sistema najbolje korelacije između RM 0 i deskriptora bile su u sistemu C-18 / metanol-voda što izdvaja ovaj hromatografski sistem kao najpogodniji za određivanje lipofilnosti analita. Na osnovu regresionih modela određeni su deskriptori koji najbolje opisuju ponašanje analita u odnosu na utvrđene retencione parametre. Dobijeni su statistički značajni modeli kvantitativnog odnosa strukture i retencije (QSRR). Izračunata lipofilnost izražena kao XlogP, površinski napon (ST) i Hansenovo vodonično vezivanje (HHB) su deskriptori koji najbolje opisuju QSRR i u višestrukoj linearnoj regresiji i u parcijalnoj regresiji najmanjih kvadrata.The framework of this thesis was to thoroughly investigate influence of structural moiety attached to A ring on chromatographic behavior of series polyoxigenated steroids under thin-layer chromatography conditions. In order to examine the effect of sorbent polarity on retention behavior of the investigated substances, two different sorbents were selected: polar unmodified silica gel and non-polar C-18 modified silica. In addition, influence of the mobile phase composition was discussed with view to determine relationship between chromatographic behavior and lipophilicity. Taking into account the nature of both sorbents and chromatographic solvents used, the chromatographic behavior of the substances was investigated under normal- and reversed-phase conditions. Polar silica gel with less polar solvents was used as typical normal-phase systems, whereas alkyl modified silica gel (RP-18 silica) in combination with polar water–organic mobile phases (methanol, acetone or acetonitrile) - for typical reversed-phase separation. It was found that in normal-phase chromatography acetone/n-hexane was more suitable for studying relationship between chromatographic behavior of the polioxigenated steroids and mobile phase composition. Under reversed-phase condition the best selectivity was achieved by the use of methanol-water mobile phase. An additional goal of this thesis was to investigate possibility of application of thin-layer chromatography for rapid and simple determination of lipophilicity as parameter of special importance for biologically active substances. A linear relationship between retention parameters of the investigated compounds and composition of the binary mobile phase used was established. On the basis of correlation between chromatographically determined lipophilicity and calculated logP values it was found that reversed-phase chromatography is useful method for lipophilicity estimation. In addition, it is appear that investigated polyoxigenated steroids represent a congeneric series of compounds. Chromatographically determined parameters of lipophilicity (RM 0) were used for developing appropriate models for structure-retention relationships by multivariate statistical analysis. The retention data for system methanol-water on C-18 silica phase has the most significant correlation between RM 0 and descriptors indicating this chromatographic system as most suitable for lipophilicity determination of the studied compounds. Retention data were correlated to molecular characteristics of the analytes with view to examine possible relationships by the means of multiple linear regression and partial least square regression. On the basis of comparison of the statistical parameters obtained for both multiple linear regression and partial least square regression models, descriptors best describing the analyte behavior were selected. Statistically significant and physically meaningful structure-retention relationships were obtained. Calculated lipophilicity expressed as XlogP as well surface tension and Hansen hydrogen bonding was included in both multiple linear regression and partial least square regression models

Supplementary data for the article: Waisi, H.; Janković, B.; Nikolić, B.; Dragičević, V.; Panić, I.; Tosti, T.; Trifković, J. Influence of Various Concentrations of 24-Epibrassinolide on the Kinetic Parameters during Isothermal Dehydration of Two Maize Hybrids. South African Journal of Botany 2018, 119, 69–79. https://doi.org/10.1016/j.sajb.2018.08.006

Supplementary material for: [https://doi.org/10.1016/j.sajb.2018.08.006]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/342

Metabolic enhancers supporting 1-carbon cycle affect sperm functionality: an in vitro comparative study

The sperm plasma membrane is a sensitive target to oxidative stress. The most representative reactive oxygen species (ROS) scavengers in the genital tract, hypotaurine and glutathione, require, for their synthesis, cysteine whose availability is associated with the 1-carbon cycle (1-CC). Human, bovine and ascidian spermatozoa were incubated with compounds supporting the 1-CC (Vitamin B6, Methylcobalamin, 5 Methyl Tetrahydrofolate, Zinc Bisglycinate and N-acetyl-cysteine) (TRT) and compared to the effects induced solely by N-acetyl-cysteine (NAC). In control groups (CNTRL), spermatozoa were incubated with medium alone. After 90 and 180 minutes of incubation, the mitochondrial membrane potential (ΔΨM) in TRT and NAC was significantly (P < 0.01) higher than in CNTRL. At H2DCFDA evaluation, ROS production differed between species whereas, at 2-OH Ethidium, it significantly decreased in bovine TRT group. Intracellular pH (pHi) did not significantly vary in relation to treatment. In ascidian spermatozoa, the NAC supplementation decreased external pH, which in turn brought to a pHi lowering. Buffering seawater with NaHCO3 reversed the beneficial effects of N-acetyl-cysteine supplementation. In conclusion, both fully supporting the 1-CC and treatment with N-acetyl-cysteine alone improved kinetics, ΔΨM and ROS production in mammalian sperm demonstrating for the first time the direct in vitro effects of these compounds on sperm functionality

The Gattini cameras for optical sky brightness measurements at Dome C, Antarctica

The Gattini cameras are two site testing instruments for the measurement of optical sky brightness, large area cloud cover and auroral detection of the night sky above the high altitude Dome C site in Antarctica. The cameras have been operating since installation in January 2006 and are currently at the end of the first Antarctic winter season. The cameras are transit in nature and are virtually identical both adopting Apogee Alta CCD detectors. By taking frequent images of the night sky we obtain long term cloud cover statistics, measure the sky background intensity as a function of solar and lunar altitude and phase and directly measure the spatial extent of bright aurora if present and when they occur. The full data set will return in December 2006 however a limited amount of data has been transferred via the Iridium network enabling preliminary data reduction and system evaluation. An update of the project is presented together with preliminary results from data taken since commencement of the winter season

Grape seed flour of different grape pomaces: Fatty acid profile, soluble sugar profile and nutritional value

The aim of this study was to determine fatty acid and soluble sugar profiles of the grape seed flour originated from non-fermented dried pomace of international and autochthonous grape varieties in order to estimate their potential nutritional value. The grape seed flours were obtained from the grapes harvested in technological maturity. It has been shown that grape seed flours contained significant quantities of unsaturated fatty acids (UFAs), especially linoleic fatty acids, whose content ranged from 61.15 - 83.47 %. Oleic acid mostly contributed to the content of monounsaturated fatty acids, while the stearic acid was the most abundant saturated fatty acid (SFA). Among polyunsaturated fatty acids, mainly ω-6 FAs, were the most represented. The tested grape seed flours had the high UFA/SFA ratio (3.63-11.09), low atherogenicity (0.04-0.13) and thrombogenicity (0.16-0.47) indices. Fifteen different sugars were found in analysed samples with the total concentration ranging from 40588 to 91319 mg/kg seed with fructose and glucose as the most abundant. Principal component analysis based on the content of FAs and soluble sugars revealed unique composition of the seed flour of Prokupac variety. These findings indicate that the tested grape seed flours is a good source of nutritionally valuable FAs and sugars that can play an important role in the formulation of a new functional food products

Definition of LCA guidelines in the geothermal sector to enhance result comparability

Geothermal energy could play a crucial role in the European energy market and future scenarios focused on sustainable development. Thanks to its constant supply of concentrated energy, it can support the transition towards a low-carbon economy. In the energy sector, the decision-making process should always be supported by a holistic science-based approach to allow a comprehensive environmental assessment of the technological system, such as the life cycle assessment (LCA) methodology. In the geothermal sector, the decision-making is particularly difficult due to the large variability of reported results on environmental performance across studies. This calls for harmonized guidelines on how to conduct LCAs of geothermal systems to enhance transparency and results comparability, by ensuring consistent methodological choices and providing indications for harmonized results reporting. This work identifies the main critical aspects of performing an LCA of geothermal systems and provides solutions and technical guidance to harmonize its application. The proposed methodological approach is based on experts’ knowledge from both the geothermal and LCA sectors. The recommendations cover all the life cycle phases of geothermal energy production (i.e., construction, operation, maintenance and end of life) as well as a selection of LCA key elements thus providing a thorough base for concerted LCA guidelines for the geothermal sector. The application of such harmonized LCA framework can ensure comparability among LCA results from different geothermal systems and other renewable energy technologies

Definition of LCA guidelines in the geothermal sector to enhance result comparability

Geothermal energy could play a crucial role in the European energy market and future scenarios focused on sustainable development. Thanks to its constant supply of concentrated energy, it can support the transition towards a low-carbon economy. In the energy sector, the decision-making process should always be supported by a holistic science-based approach to allow a comprehensive environmental assessment of the technological system, such as the life cycle assessment (LCA) methodology. In the geothermal sector, the decision-making is particularly difficult due to the large variability of reported results on environmental performance across studies. This calls for harmonized guidelines on how to conduct LCAs of geothermal systems to enhance transparency and results comparability, by ensuring consistent methodological choices and providing indications for harmonized results reporting. This work identifies the main critical aspects of performing an LCA of geothermal systems and provides solutions and technical guidance to harmonize its application. The proposed methodological approach is based on experts' knowledge from both the geothermal and LCA sectors. The recommendations cover all the life cycle phases of geothermal energy production (i.e., construction, operation, maintenance and end of life) as well as a selection of LCA key elements thus providing a thorough base for concerted LCA guidelines for the geothermal sector. The application of such harmonized LCA framework can ensure comparability among LCA results from different geothermal systems and other renewable energy technologies

Decolorization of reactive black 5 using dielectric barrier discharge in the presence of inorganic salts

Inorganic salts improve the coloration of textiles, which increase pollution load on dyehouse effluent in general. Decolorization of reactive textile dye C.I. Reactive Black 5 was studied using Advanced Oxidation Processes (AOPs) in a non-thermal plasma reactor, based on coaxial water falling film Dielectric Barrier Discharge (DBD). Initial dye concentration in the solution was 40.0 mg L-1. The effects of addition of inorganic salt different high concentrations (NaCl, Na2SO4 and Na2CO3) on the degree of decolorization were studied. Recirculation of dye solution through the DBD reactor with applied energy density 45-315 kJ L-1 was used. The influence of residence time was investigated after 5 minutes and 24 hours of plasma treatment. Decolorization of the dyes was monitored by spectrophotometric measurement. Changes of pH values and the conductivity of dye solution after each recirculation were tested. The most effective decolorization of over 90% was obtained with the addition of NaCl (50 g L-1), applied energy density of 135 kJ L-1 and after residence time of 24 hours of plasma treatment. Decolorization of solutions containing inorganic salts Na2SO4 and Na2CO3 were lower than for the solution without salt