AYLAX PAPAVERIS (PERRIS 1839) AND (BARBBARBOTINIA ORANIENSIS OTIN 1964): SPECIES NEW TO THE FAUNA OF CYNIPID GALL WASPS (HYMENOPTERA, CYNIPIDAE) OF SERBIA

Never recorded before in Serbia, the cynipid gall wasps  Aylax papaveris  (Perris 1839) and  Barbotinia oraniensis (Barbotin 1964) were obtained from capsules of Papaver rhoeas Linnaeus 1753 collected toward the end of June 1998 at the locality Surduk (Srem, Serbia). Nine species of parasitoids were also obtained. Among them were the species Ormyrus capsalis Askew 1994 and Baryscapus papaveris Graham 1991, never before found in Serbia

Optimization of the preparation of novel polymer/clay nanocomposites

Recent advances in material technologies have resulted in the preparation of novel polymer/clay composites with improved thermal, mechanical, optoelectronic/ magnetic properties and increased biodegradability [1]. In this study, six samples of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (PGME) nanocomposites with organically-modified montmorillonite clay Cloisite 30B® (C30B), were prepared via suspension copolymerization. In order to obtain nanocomposites with fine spherical beads of regular shape and satisfying thermal stability the optimization of the synthesis conditions was performed. Firstly, the influence of the poly(N-vinyl pyrrolidone) (PVP) quantity in the aqueous phase was varied (1, 3 and 5 wt.%) at a constant stirring rate of 250 rpm and constant clay content C30B (10 wt.%). In the second phase of the optimization of the preparation, samples with a constant composition of the composite reaction mixture (5 wt.% PVP and 10 wt.% C30B) at a stirring rate of 250, 325 and 400 rpm, were prepared. According to the obtained results, it was concluded that the optimal conditions for preparation of these composites are 5 wt.% of PVP and 400 rpm. The prepared nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) in air. The structure of the prepared nanocomposites was confirmed with FTIR spectroscopy. According to the obtained SEM microphotographs the fine spherical beads, with desired size and homogeneous morphology, were prepared. Furthermore, SEM analysis was also showed that clay nanoparticles are homogeneously dispersed both inside surface and cross-section area. The incorporation of C30B clay increased the thermal stability of the prepared polymer/clay nanocomposites in comparison to the pure PGME copolymer

Optimization of the preparation of novel polymer/clay nanocomposites

Recent advances in material technologies have resulted in the preparation of novel polymer/clay composites with improved thermal, mechanical, optoelectronic/ magnetic properties and increased biodegradability [1]. In this study, six samples of poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) (PGME) nanocomposites with organically-modified montmorillonite clay Cloisite 30B® (C30B), were prepared via suspension copolymerization. In order to obtain nanocomposites with fine spherical beads of regular shape and satisfying thermal stability the optimization of the synthesis conditions was performed. Firstly, the influence of the poly(N-vinyl pyrrolidone) (PVP) quantity in the aqueous phase was varied (1, 3 and 5 wt.%) at a constant stirring rate of 250 rpm and constant clay content C30B (10 wt.%). In the second phase of the optimization of the preparation, samples with a constant composition of the composite reaction mixture (5 wt.% PVP and 10 wt.% C30B) at a stirring rate of 250, 325 and 400 rpm, were prepared. According to the obtained results, it was concluded that the optimal conditions for preparation of these composites are 5 wt.% of PVP and 400 rpm. The prepared nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA) in air. The structure of the prepared nanocomposites was confirmed with FTIR spectroscopy. According to the obtained SEM microphotographs the fine spherical beads, with desired size and homogeneous morphology, were prepared. Furthermore, SEM analysis was also showed that clay nanoparticles are homogeneously dispersed both inside surface and cross-section area. The incorporation of C30B clay increased the thermal stability of the prepared polymer/clay nanocomposites in comparison to the pure PGME copolymer

Treatment of Waste Copper Electrolytes Using Insoluble and Soluble Anodes

The use of copper anodes with non standard content of impurities for the treatment of waste, sulphur acid solutions that came as a result of the industrial process of electrolytic copper refining was investigated. Those solutions contain the high content of copper, nickel and arsine, and because of that, the copper anodes with high content of Ni, Pb, Sn and Sb were prepared. Examination the effect of high impurities content as well as the influence of the solution temperature on the anodes behaviour during the electrolytic process under the conditions that are the same as the industrial was the aim of this work. Obtained results clearly indicate that tested anodes could be used for the refined during the electrorefining process. Dissolution of copper anodes was not stoppage after the first appearance of the passivation region for A1 and A2 anodes while appearance of passivation for A3 anode, for test duration of 72 h, was not registered. The start time of the first passivation appearance is shorter in the case of the anode with high content of all impurities, anode A1. The first passivation occurrence was detected on higher temperature after about 29 h from the test starts. The change of chemical composition of electrolyte was monitored during electrolysis. Concentration of nickel in the working electrolyte at the end of process is increased and it corresponds to the Ni content in anodes. The copper and arsenic concentrations are decreased during the process. Arsenic passes into the anode slime, while the copper is deposited on the cathode and also passed in the slime. After the process is finished, obtained solution could be used for the nickel recover using the electrochemically or chemically methods

Elektrohemijska degradacija Reactive Black 5 pomocu celicnih elektroda modifikovanih PbO2 i grafitnim ugljen-nitridom

Elektrode modifikovane kompozitom PbO2 sa grafitnim ugljen-nitridom (GCN) upotrebljene su za elekrohemijsku degradaciju tekstilne boje Reactive Black 5. Modifikovana čelična elektroda je korišćena kao anoda, a kao katoda čista čelična elektroda. Ispitan je uticaj strukture PbO2 na elektrokatalitičke karakteristike elektroda. Morfologija materijala je ispitana SEM-om, TEM-om i XRD-om, dok su elektrohemijske osobine ispitane uz pomoć CV i EIS merenja. Efikasnost degradacije je praćena UV-Vis spektrofotometrijom i tečnom hromatografijom. Pri optimalnim parametrima pH, koncentracije pomoćnog elektrolita, jačine struje i koncentracije ispitivane boje, najbolji rezultati su dobijeni sa elektrodom gde je cetiltrimetilamonijum-bromid (CTAB) korišćen kao templat za sintezu PbO2. Pod ovim uslovima je postignuta potpuna degradacija nakon 60 min tretmana, a proizvodi degradacije su određeni korišćenjem HPLC-MS/MS metode.Electrodes modified by PbO2 and graphite carbon nitride (GCN) composite were used for electrochemical degradation of Reactive Black 5 textile dye. A modified steel electrode was used as the anode, while a pure steel electrode was used as the cathode. The influence of PbO2 structre on electrocatalytic characteristics of electrodes was investigated. The morphology of the material was examined by SEM, TEM and XRD, while the electrochemical properties were analyzed using means of CV and EIS measurements. The degradation efficiency was monitored by UV-Vis spectrophotometry and liquid chromatography. At optimal pH parameters, supporting electrolyte concentration, current strength and test dye concentration, the best results were obtained with an electrode where cetyl trimethyl ammonium bromide (CTAB) was used as a template for PbO2 synthesis. Under these conditions, complete degradation was achieved after 60 min of treatment, and degradation products were determined using the HPLC-MS/MS method.Abstract: [https://hdl.handle.net/21.15107/rcub_cherry_6058

LEVEL CROSSING RATE OF MACRODIVERSITY SYSTEM OVER COMPOSITE GAMMA SHADOWED ALPHA-KAPPA-MU MULTIPATH FADING CHANNEL

In this paper macrodiversity system with macrodiversity selection combining (SC) receiver and two microdiversity SC receivers operating over composite shadowed multipath fading environment is considered. Received signal is subjected simultaneously to gamma long term fading and α-κ-μ short term fading resulting in system performance degradation. Macrodiversity SC receiver reduces gamma long term fading effects and microdiversity SC receivers mitigate α-κ-μ short term fading effects. Analitical expression for average level crossing rate of proposed wireless mobile system represented as an infinite series is evaluated. Mathematical and numerical analysis are shown influences of gamma fading severity, α-κ-μ multipath fading severity, and Rician factor on average level crossing rate

Elektrohemijska degradacija Reactive Black 5 pomocu celicnih elektroda modifikovanih PbO2 i grafitnim ugljen-nitridom

Elektrode modifikovane kompozitom PbO2 sa grafitnim ugljen-nitridom (GCN) upotrebljene su za elekrohemijsku degradaciju tekstilne boje Reactive Black 5. Modifikovana čelična elektroda je korišćena kao anoda, a kao katoda čista čelična elektroda. Ispitan je uticaj strukture PbO2 na elektrokatalitičke karakteristike elektroda. Morfologija materijala je ispitana SEM-om, TEM-om i XRD-om, dok su elektrohemijske osobine ispitane uz pomoć CV i EIS merenja. Efikasnost degradacije je praćena UV-Vis spektrofotometrijom i tečnom hromatografijom. Pri optimalnim parametrima pH, koncentracije pomoćnog elektrolita, jačine struje i koncentracije ispitivane boje, najbolji rezultati su dobijeni sa elektrodom gde je cetiltrimetilamonijum-bromid (CTAB) korišćen kao templat za sintezu PbO2. Pod ovim uslovima je postignuta potpuna degradacija nakon 60 min tretmana, a proizvodi degradacije su određeni korišćenjem HPLC-MS/MS metode.Electrodes modified by PbO2 and graphite carbon nitride (GCN) composite were used for electrochemical degradation of Reactive Black 5 textile dye. A modified steel electrode was used as the anode, while a pure steel electrode was used as the cathode. The influence of PbO2 structre on electrocatalytic characteristics of electrodes was investigated. The morphology of the material was examined by SEM, TEM and XRD, while the electrochemical properties were analyzed using means of CV and EIS measurements. The degradation efficiency was monitored by UV-Vis spectrophotometry and liquid chromatography. At optimal pH parameters, supporting electrolyte concentration, current strength and test dye concentration, the best results were obtained with an electrode where cetyl trimethyl ammonium bromide (CTAB) was used as a template for PbO2 synthesis. Under these conditions, complete degradation was achieved after 60 min of treatment, and degradation products were determined using the HPLC-MS/MS method.Poster: [https://hdl.handle.net/21.15107/rcub_cherry_6059

Geomorphological and hydrological heritage of Mt. Stara Planina in SE Serbia: From river protection initiative to potential geotouristic destination

Mt. Stara Planina is located in the eastern part of the Republic of Serbia and represents the westernmost part of the large mountain massif of the Balkans. Both endogenous and exogenous forces created interesting geomorphological and hydrological features for geotourism development in this area. This article proposes a preliminary list of geomorphological and hydrological sites and analyses them to reveal which geosite possesses geotourism potential. This research was carried out by applying the modified geosite assessment model. In this article, ten geosites were singled out based on the degree of their attractiveness for geotourism development. The results reveal information about the key fields of improvement for each evaluated geosite, and identify which areas require more attention and better management in the upcoming period for Mt. Stara Planina to become a well-known geotourism destination that would attract a large number of tourists in the future

Wear of internal combustion engine parts with possibilities for their regeneration

Only 12% of the total energy of the fuel finds its way to the driving wheels, while 15% of it is being dissipated as mechanical, mainly frictional losses. These numbers could be improved by applying methods of reparation and regeneration of engine parts, which are subject of this paper. If it is taken into account the time elapsed between ordering and delivery of the new engine, the price of it including import taxes, it is economically justified to do regeneration of the worn components instead of ordering the new one. In this paper are explained the most common damages of IC engine parts, diagnostics and possible solutions for their regeneration