Electrochemical Reduction of Trinitrotoluene on a Modified Platinum Electrode

Poster presented at the 61st Annual Meeting of the International Society of Electrochemistry, Nice, France, September 26 – October 1, 201

Modelling the evolution and nucleosynthesis of carbon-enhanced metal-poor stars

We present the results of binary population simulations of carbon-enhanced metal-poor (CEMP) stars. We show that nitrogen and fluorine are useful tracers of the origin of CEMP stars, and conclude that the observed paucity of very nitrogen-rich stars puts strong constraints on possible modifications of the initial mass function at low metallicity. The large number fraction of CEMP stars may instead require much more efficient dredge-up from low-metallicity asymptotic giant branch stars.Comment: 6 pages, 1 figure, to appear in the proceedings of IAU Symposium 252 "The Art of Modelling Stars in the 21st Century", April 6-11, 2008, Sanya, Chin

Properties of elastomeric materials based on polychloroprene/chlorosulfonated polyethylene rubber blends

In this work the elastomeres based on polychloroprene/chlorosulphonated polyethylene rubber blends (CR/CSM) intended for rubber-metal bonding has been studied. The rheographs and curing characteristics of blends reinforced by active precipitated silica and diatomaceous earth were obtained using a Monsanto rheometer. Crosslinking has been performed by sulphur at 160 °C up to optimum cure time. Temperature dependence of storage modulus (E’), tanδ and glass transition temperature were determinated by mechanical spectroscopy. Adhesion strength has been measured by two methods. It was concluded that a adhesion strength value can be increased by using nano fillers as reinforcing agensPhysical chemistry 2004 : 7th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 21-23 September 200

Microwave synthesis of new star shaped polyester polyols based on L-lactide

The molecular architecture of biodegradable polymers can be adjusted by incorporating multifunctional polyols into the polyester backbone to obtain branched polymers. The aim of our work was to prepare biodegradable polyester polyols based on L-lactide and castor oil in presence of tin(II) 2-ethylhexanoate as catalyst in microwave field. The polyester polyol was synthesized by core-first method which involves a polymerization of L-lactide from OH groups on castor oil. FTIR and 1 H NMR spectroscopy measurements were used to confirm the molecular structure of the synthesized products. DSC measurements were used to evaluate the crystallinity of obtained polyols. Thermal stability was investigated by thermogravimetric analysis, and results have shown the dependence of thermal stability on the arm length of the star shaped polyesters.Physical chemistry 2012 : 11th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 24-28 September 201

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

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

Detection of opsonizing antibodies directed against a recently circulating Bordetella pertussis strain in paired plasma samples from symptomatic and recovered pertussis patients.

Correlates of protection (CoPs) against the highly contagious respiratory disease whooping cough, caused by Bordetella pertussis, remain elusive. Characterizing the antibody response to this pathogen is essential towards identifying potential CoPs. Here, we evaluate levels, avidity and functionality of B. pertussis-specific-antibodies from paired plasma samples derived from symptomatic and recovered pertussis patients, as well as controls. Natural infection is expected to induce protective immunity. IgG levels and avidity to nine B. pertussis antigens were determined using a novel multiplex panel. Furthermore, opsonophagocytosis of a B. pertussis clinical isolate by neutrophils was measured. Findings indicate that following infection, B. pertussis-specific antibody levels of (ex-) pertussis patients waned, while the avidity of antibodies directed against the majority of studied antigens increased. Opsonophagocytosis indices decreased upon recovery, but remained higher than controls. Random forest analysis of all the data revealed that 28% of the opsonophagocytosis index variances could be explained by filamentous hemagglutinin- followed by pertussis toxin-specific antibodies. We propose to further explore which other B. pertussis-specific antibodies can better predict opsonophagocytosis. Moreover, other B. pertussis-specific antibody functions as well as the possible integration of these functions in combination with other immune cell properties should be evaluated towards the identification of CoPs against pertussis