Both oxidation and methoxymethylation of the surfaces of a series of MDI (methylene diphenyl isocyanate) and TDI (toluene
diisocyanate) polyether and polyester soft segment 1–4 butanediol polyurethanes result in increased thermal stability as measured
by TG. Explosive loss of mass above the hard segment melting temperature suggests that the diffusion of the dissociated diisocyanate
moiety is hindered at lower temperatures. Thus suppression of the depolycondensation reaction by chemical blockage of the
surface may result in a material with an increased service life at use temperatures as thermal stability of a polyurethane
may depend upon the low diffusivity of its diisocyanate comonomer. The effect of vacuum, oxygen and water vapor on the kinetics
of mass-loss of several of the polyurethanes is presented.
Authors:A. F. Petrović, S. R. Lukić, D. M. Petrović, E. Z. Ivegeš, and V. M. Leovac
The thermal decomposition of tetrahedral cobalt(II) complexes with 3(5)-amino-4-acetyl5(3)-methylpyrazole (HL) of the general formula [Co(HL)2X2] (X=Cl, Br, I, NCO, NCS) and octahedral [Co(HL)2(H2O)4](NO3)2 and [Co(HL)2−N(CN)2}2] complexes was investigated in air atmosphere in the interval from room temperature to 1000°C. Decomposition of the complexes occurred in several successive endothermic and exothermic processes, and the residue was in all cases CoO.
Authors:T. Trtić, L. Vuksanović, S. Paranos, S. Petrović, Z. Vujčić, I. Plećas, and R. Jankov
One of the frequent causes of pollen allergy in our region (Serbia, Yugoslavia) is the pollen of poplar (Populus canadensis). The aim of this study was to form RAST for the determination of specific anti-Populus canadensis IgE antibodies. Affinity purified and radiolabelled (I-125) MoAb E1 was used for forming assay for the determination of specific IgE. By titration of extract of poplarPopulus canadensis we determined that the quantity of 0.65 mL extract is needed for coupling of lg BrCN activated paper discs. Coupling was performed in Na2CO3/NaHCO3 buffer pH 10, on 4°C for 48h. Using this newely formed RAST, specific forPopulus canadensis, we have deteminated anti-Populus canadensis IgE antibodies as well as cross reactivity between pollens ofPopulus canadensis andPopulus deltoides.
Authors:K.G. Mladenović, M.Ž. Muruzović, O.D. Stefanović, T.D. Žugić Petrović, and Lj.R. Čomić
The antibacterial activity of potassium metabisulphite, potassium benzoate, potassium propionate, and potassium nitrate were evaluated against 15 species of bacteria using diffusion and microdilution methods. Potassium metabisulphite showed the greatest activity (MIC varied in the range of 0.78 mg ml–1 to 3.12 mg ml–1), then potassium benzoate (6.25 mg ml–1 to 12.5 mg ml–1) followed by potassium propionate and potassium nitrate (6.25 mg ml–1 to 100 mg ml–1). Effects of potassium benzoate, potassium propionate, and potassium nitrate on the sugar fermentation, the effect of potassium benzoate on cell membrane permeability and on amylolytic activity of bacteria were tested. The results indicated inhibition of fermentation, loss of intracellular macromolecules (proteins) from treated cells, and inhibition of amylolytic activity.
Authors:V. Tomović, Lj. Petrović, M. Jokanović, M. Tomović, Ž. Kevrešan, T. Tasić, P. Ikonić, B. Šojić, S. Škaljac, and M. Šošo
Concentration of phosphorous (P), potassium (K), sodium (Na), magnesium (Mg), calcium (Ca), iron (Fe), zinc (Zn), copper (Cu), and manganese (Mn) was determined in the kidney tissue of sixty-nine pigs belonging to ten different genetic lines of pigs, produced in Vojvodina (northern Serbia). Phosphorous was determined by the standard spectrophotometric method. Metals were determined by the flame atomic absorption spectrometry after mineralization by dry ashing. The order of the minerals in the kidney tissue and their content ranges in mg/100 g was P (246–347, on average 287) > K (142–236, on average 189) > Na (102–187, on average 130) > Mg (17.8–36.6, on average 23.3) > Ca (15.9–27.7, on average 20.2) > Fe (5.32–10.42, on average 7.42) > Zn (2.15–4.10, on average 2.99) > Cu (0.62–2.15, on average 1.29) > Mn (0.16–0.30, on average 0.22). Genetic lines of pigs had no influence on mineral concentrations of kidney (P>0.05). The Vojvodian pig kidney showed slightly lower K, slightly higher P and Mn, and higher Ca contents, compared to the values reported in the literature.