Inhibiting effect of acetonitrile on oxygen reduction on polycrystalline pt electrode in sodium chloride solution

The oxygen reduction reaction (ORR) was studied on the polycrystalline Pt electrode in 0.1 M NaCl electrolyte containing various amounts of acetonitrile (AcN). The state of the electrode surface was characterized by the cyclic voltammetry in oxygen free electrolytes, while ORR studies were performed on the polycrystalline Pt rotating disc electrode by the linear sweep voltammetry in oxygen saturated electrolytes. The acetonitrile is chemisorbed on Pt over a wide potential range, inhibiting both hydrogen adsorption and oxide formation. The extent of AcN chemisorption depends on its concentration in the solution. Initial potential of oxygen reduction is shifted negatively, while the ORR current is increasingly reduced with the increase of AcN concentration. Complete inhibition of ORR in the potential range of AcN and Cl-anion coadsorption is achieved for (0.1 M NaCl + 1 M AcN) solution

Quality of the river Ibar from Biljanovac to Kraljevo

Voda reke Ibar se koristi za vodosnabdevanje kao i za potrebe stanovništva mnogih mesta, stoga je praćenje kvaliteta vode reke Ibar od primarnog značaja za utvrđivanje kontaminiranosti vodenog ekosistema i zaštite čovekovog zdravlja. Rad je nastavak projekta monitoringa reke Ibar od Raške do Kraljeva. Na 34. međunarodnom stručno-naučnom skupu na Tari je dat uticaj otpadnih voda opštine Raška i Baljevca na kvalitet reke Ibar. A cilj ovog rada je da se prikaže uticaj svih naseljenih mesta od Biljanovca do Konareva na kvalitet vode reke Ibar. Ukupno 15 merenja na 3 merna mesta u dužini oko 50 km. Reka Ibar prolazi kroz naseljena mesta gde je razvijena industrija i kroz nenaseljena mesta.The water of the Ibar river is used for water supply and other purposes, so monitoring the water quality of the river Ibar of primary importance for the contamination of water ecosystems and protecting human health. This paper is a continuation of the monitoring of the Ibar river of Raska and Kraljevo. Last year, at the 34th international professional scientific meeting at Tara was given the impact of wastewater municipality of Raška and Baljevac the quality of the Ibar river. A goal of this paper is to show the impact of settlements from Biljanovac to Konarevo the water quality of the Ibar river. Total of 15 measurements at three measuring sites separated 50 km are presented. The Ibar river is passing both through urban areas where the industry is developed and through uninhabited places

Textural properties of macroporous acid modified montmorillonite nanocomposites

Macroporous crosslinked copolymer, poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) and its nanocomposites with acid modified montmorillonite (WA) were synthesized by radical suspension copolymerization. Nanocomposites were obtained by introducing various amounts of WA into the reaction system. Textural properties of synthesized samples were analyzed by mercury intrusion porosimetry. The synthesized nanocomposites have significantly higher specific surface area in comparison to the copolymer. Total pore volume and the most dominant pore diameter decrease with incorporation of acid modified montmorillonite in copolymer matrix.Physical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

Mass Transfer by Stellar Wind

I review the process of mass transfer in a binary system through a stellar wind, with an emphasis on systems containing a red giant. I show how wind accretion in a binary system is different from the usually assumed Bondi-Hoyle approximation, first as far as the flow's structure is concerned, but most importantly, also for the mass accretion and specific angular momentum loss. This has important implications on the evolution of the orbital parameters. I also discuss the impact of wind accretion, on the chemical pollution and change in spin of the accreting star. The last section deals with observations and covers systems that most likely went through wind mass transfer: barium and related stars, symbiotic stars and central stars of planetary nebulae (CSPN). The most recent observations of cool CSPN progenitors of barium stars, as well as of carbon-rich post-common envelope systems, are providing unique constraints on the mass transfer processes.Comment: Chapter 7, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G. Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe

The Blue Stragglers of the Old Open Cluster NGC 188

The old (7 Gyr) open cluster NGC 188 has yielded a wealth of astrophysical insight into its rich blue straggler population. Specifically, the NGC 188 blue stragglers are characterized by: A binary frequency of 80% for orbital periods less than $10^4$ days;Typical orbital periods around 1000 days;Typical secondary star masses of 0.5 M$_{\odot}$; At least some white dwarf companion stars; Modestly rapid rotation; A bimodal radial spatial distribution; Dynamical masses greater than standard stellar evolution masses (based on short-period binaries); Under-luminosity for dynamical masses (short-period binaries). Extensive $N$-body modeling of NGC 188 with empirical initial conditions reproduces the properties of the cluster, and in particular the main-sequence solar-type binary population. The current models also reproduce well the binary orbital properties of the blue stragglers, but fall well short of producing the observed number of blue stragglers. This deficit could be resolved by reducing the frequency of common-envelope evolution during Roche lobe overflow. Both the observations and the $N$-body models strongly indicate that the long-period blue-straggler binaries - which dominate the NGC 188 blue straggler population - are formed by asymptotic-giant (primarily) and red-giant mass transfer onto main sequence stars. The models suggest that the few non-velocity-variable blue stragglers formed from mergers or collisions. Several remarkable short-period double-lined binaries point to the importance of subsequent dynamical exchange encounters, and provide at least one example of a likely collisional origin for a blue straggler.Comment: Chapter 3, in Ecology of Blue Straggler Stars, H.M.J. Boffin, G. Carraro & G. Beccari (Eds), Astrophysics and Space Science Library, Springe

The influence of different doses of γ-radiation on the hydrolytic stability of modified urea-formaldehyde (UF) resins

Zbog emisije formaldehida (CH2 O) iz drvenih proizvoda, gde se urea- formaldehidne (UF) smole, između ostalog, koriste za impregnaciju drvenih panela koje se koriste u unutrašnjosti stambenih i drugih objekata poželjno je da procenat slobodnog formaldehida (CH2 O) u samoj smoli bude što manji, jer je poznato da formaldehid ima štetno dejstvo na čoveka, odnosno ceo živi svet. Pare formaldehida jako nadražuju disajne puteve. Koncentracije od 10-20 ppm otežavaju disanje, a koncentracije od 650 ppm mogu uzrokovati i smrt za samo nekoliko minuta. Često udisanje para niskih koncentracija mogu uzrokovati hronična oboljenja disajnih puteva. Simptomi i granice su individualni i javljaju se u širokim granicama izloženosti. Pojedine osobe mogu da osete simptome, kao što su iritacija očiju, grla, umor, glavobolja i mučnina, usled izloženosti i niskoj koncentaciji formaldehida (0.1 do 1 ppm). Osim slobodnog formaldehida, u samoj smoli, koji se spontano emituje, zbog niske otpornosti na vlagu, može doći do hidrolize UF smole što podrazumeva raskidanje samih veza u smoli (metilenetarskih) i dodatne emisije formaldehida u okolinu [1,2]. U ovom radu je ispitivana hidrolitička stabilnost modifikovanih UF smola sa “hvatačima” formaldehida, TiO2 sa različitim sadržajem (3,75 g i 7,25 g) u UF smoli i kombinacijom TiO2 i drvnog brašna (TiO2 /DB) u ekvimolarnim količinama. Tri modifikovane UF smole s odnosom formaldehida i uree (F/U) 0.8 s modifikovanim punilima su sintetizovani istim postupkom [3]. Hidrolitička stabilnost ispitivanih modifikovanih UF smola je određivana merenjem koncentracije oslobođenog formaldehida [4] iz modifikovane UF smole nakon kisele hidrolize. Zračenje sintetisanih modifikovanih smola je vršeno u vazdušnoj atmosferi u Co-60 radijacionoj jedinici na Institutu za nuklearne nauke, Vinča, Srbija. Uzorci smola su zračeni γ–zračenjem na sobnoj temperaturi i ukupnom apsorbovanom dozom od 50 kGy i 100 kGy [5]. Pre zračenja najmanji procenat slobodnog formaldehida (0.06%) imaju uzorci koji su modifikovani TiO2 . Usled γ-zračenja dolazi do degradacije makromolekula što uzrokuje povećanje slobodnog formaldehida u zračenim uzorcima u odnosu na nezračene. Povećanje doze zračenja sa 50 kGy na 100 kGy dovodi do smanjenja količine slobodnog formaldehida u umreženoj UF smoli. Najmanji procenat slobodnog formaldehida nakon zračenja sa ukupnom apsorbovanom dozom od 100 kGy nalazi se u UF smoli koja sadrži 100% TiO2 u količini od 0.12%. S druge strane i drvno brašno koje sadrži celulozu i hemicelulozu ima veliki broj hidroksilnih grupa, takođe reaguje sa slobodnim formaldehidom iz UF smole. γ-zračenjem je smanjen procenat oslobođenog formaldehida u svim ispitivanim modifikovanim UF smolama, posebno kod uzoraka smole sa TiO2 u količini od 100% u izosu od 0.25%. To se objašnjava činjenicom da kisela hidroliza nakon zračenja dovodi do dodatnog umrežavanja u svim uzorcima, što rezultuje „hvatanjem“ formaldehida u toku samog procesa hidrolize. Uzorci ispitivane kompozitne smole sa TiO2 /DB pokazuju lošiju hidrolitičku stabilnot zbog povećane interakcije između hidroksilnih i karbonilnih grupa u drvnom brašnu i hidroksilnih grupa sa površine TiO2 , zbog čega dolazi do smanjene interakcije hibridnog punila sa polimernom matricom odnosno smanjuje se procenat slobodnih grupa koje bi inače reagovale sa formaldehidom i smanjile njegovu emisiju iz smole.8th Symposium Chemistry and Environmental Protection : May 30 - June 1, Kruševac, 2018

Progress and Research Needs of Plant Biomass Degradation by Basidiomycete Fungi

Peer reviewe

The politics of performance: transnationalism and its limits in former Yugoslav popular music, 1999–2004

This paper examines transnational relations between the Yugoslav successor states from the point of view of popular music, and demonstrates how transnational musical figures (such as Djordje Balaševi?, Mom?ilo Bajagi?-Bajaga and Ceca Ražnatovi?) are interpreted as symbolic reference points in national ethnopolitical discourse in the process of identity construction. Another symbolic function is served by Serbian turbofolk artists, who in Croatia serve as a cultural resource to distance oneself from a musical genre associated by many urban Croats with the ruralization (and Herzegovinization) of Croatian city space. In addition, value judgements associated with both Serbian and Croatian newly composed folk music provide an insight into the transnational negotiation of conflicting identities in the ex-Yugoslav context. Ultimately the paper shows how the ethnonational boundaries established by nationalizing ideologies created separate cultural spaces which themselves have been transnationalized after Yugoslavia's disintegration