Authors:D. Petrovic-Djakov, J. Filipovic, Lj. Vrhovac, and J. Velickovic
Glass transition temperatures of blends of (1) poly-(phenyl methacrylate) and poly(2,3-xylenyl methacrylate), (2) poly-(phenyl
methacrylate) and poly(2,6-xylenyl methacrylates and (3) poly-(2,3-xylenyl-) and poly(2,6-xylenyl methacrylate) were measured.
The data obtained suggest the existance of compatibility for blends of poly(xylenyl methacrylates) mentioned and incompatibility
for both poly(phenyl methacrylate)/poly(xylenyl methacrylate) systems.
Authors:J. Filipovic, D. Petrovic-Djakov, Lj. Vrhovac, and J. Velickovic
The free radical copolymerization of phenyl methacrylate (PhMA) witho-methylphenyl-methacrylate(o-MPhMA) ando-ethylphenyl methacrylate (o-EPhMA) was carried out and the enthalpies of copolymerization, overall rate constants and copolymerization parameters were
determined for different molar ratios of comonomers in the temperature range 353–373 K.
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:J. M. Filipovic, D. M. Petrovic-Dakov, Lj. P. Vrhovac, and J. S. Velickovic
The course and kinetics of free radical polymerization in bulk ofp-alkylphenyl methacrylates with AIBN initiator were studied by DSC, in the temperature range 348–373 K. The enthalpy of polymerization, the residual monomer content, as well as the overall reaction rate constants and the activation energies were determined. The similar values of the overall rate constants indicate that the relatively small alkyl substituents inp-position of the phenyl ring affect the polymerization rate to a very small, if any, extent.
Authors:D. M. Petrović-Djakov, J. M. Filipović, Lj. P. Vrhovac, and J. S. Veličković
The kinetics of the AIBN-initiated free radical bulk polymerization of fiveo-alkylphenyl methacrylates was studied by means of DSC in the temperature range 353–373 K, and the enthalpy of polymerization, the overall reaction rate constant and the activation energy were determined. The results were compared with those published recently on correspondingp-alkylaryl methacrylates. All measured reaction rate constants were found to increase with increasing temperature and to decrease with increasingo-alkyl substituent mass and size. It was shown thato-substituents influence the rates of polymerization to a greater extent thanp-substituents. At about 373 K, all differences in rate, most probably resulting from steric hindrance caused by the alkyl groups, disappear in both series, a phenomenon earlier observed for dimethyl phenyl methacrylates.
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.