Studentski Trg 12 16

Belgrade, Serbia

Studentski Trg 12 16

Belgrade, Serbia
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PubMed | University of Belgrade, University of New Orleans, Texas A & iversity at Qatar and Studentski trg 12 16
Type: Journal Article | Journal: Chemphyschem : a European journal of chemical physics and physical chemistry | Year: 2016

The hydrogen bonding of noncoordinated water molecules to each other and to water molecules that are coordinated to metal-ion complexes has been investigated by means of a search of the Cambridge Structural Database (CSD) and through quantum chemical calculations. Tetrahedral and octahedral complexes that were both charged and neutral were studied. A general conclusion is that hydrogen bonds between noncoordinated water and coordinated water are much stronger than those between noncoordinated waters, whereas hydrogen bonds of water molecule in tetrahedral complexes are stronger than in octahedral complexes. We examined the possibility of correlating the computed interaction energies with the most positive electrostatic potentials on the interacting hydrogen atoms prior to interaction and obtained very good correlation. This study illustrates the fact that electrostatic potentials computed for ground-state molecules, prior to interaction, can provide considerable insight into the interactions.

Gizdavic-Nikolaidis M.R.,University of Auckland | Jevremovic M.M.,Vinča Institute of Nuclear Sciences | Allison M.C.,University of Auckland | Stanisavljev D.R.,Studentski Trg 12 16 | And 4 more authors.
Express Polymer Letters | Year: 2014

For the first time, microwave assisted aniline oxidative polymerization is performed in the presence of acetic acid (CH3COOH) and ammonium hydroxide (NH4OH) at different microwave power levels. The reaction system is kept at constant temperature of 24±1°C. The products are investigated by Fourier Transform Infrared Spectroscopy (FTIR), Raman, solid-state Nuclear Magnetic Resonance (NMR) and Electron Paramagnetic Resonance (EPR) spectroscopies. EPR signals in polyaniline (PANI) originate from the polarons formed upon protonation and doping by acid. The microwave radiation causes an increase in the spin concentration which is slightly more evident for 8 W than for 93 W. The morphology is investigated by using scanning electron microscopy (SEM). SEM micrographs revealed the formation of nanorods (in the presence of CH3COOH) and nanospheres (in the presence of NH4OH). FTIR, Raman and solid-state NMR spectroscopies indicate the presence of PANI and aniline oligomers. X-ray Diffraction (XRD) measurements showed the presence of well-ordered structures. © BME-PT.

Andjelkovic I.,Studentski Trg 12 16 | Manojlovic D.,Studentski Trg 12 16 | Skrivanj S.,Studentski Trg 12 16 | Pavlovic B.M.,B. Kralja Aleksandra 73 | And 2 more authors.
International Journal of Environmental Research | Year: 2013

Nanoparticles of manganese-dioxide synthesized by mechano-chemical reaction were used for As(III) and As(V) sorption from water environment. The influence of a milling time of manganese-dioxide on sorption was examined with batch procedure. Sorption as a function of contact time was investigated. Kinetic of sorption, for both As(III) and As(V), was fast. The equilibrium condition for milled sorbents was achieved after one hour of mixing. Experimental data were fitted to Freundlich and Langmuir adsorption models. Both models represent experimental data well with slightly better regression coefficient for Freundlich isotherm model. With the increase of the milling time manganese-dioxide adsorption capacity for As(III) and As(V) increased. The decrease of average particle size with milling could be responsible for increase of sorption capacity. The influence of pH on sorption was also investigated. The sorption of both, As(III) and As(V), in investigated pH range (6.0-9.0) was not significantly disturbed and showed similar behaviour, what could indirectly imply oxidation of As(III) to As(V) before sorption.

Radovanovic A.N.,Studentski trg 12 16 | Jovancicevic B.S.,Studentski trg 12 16 | Radovanovic B.C.,Visegradska 33 | Mihajilov-Krstev T.,Visegradska 33
Tropical Journal of Pharmaceutical Research | Year: 2014

Purpose: The aim of this study was to assess potential antimicrobial effectiveness of selected red wines from Balkan region, made from autochthonic Vranac V. vinifera L. grape variety. Methods: The antimicrobial activity of Vranac wines against Gram-positive: C. perfringens, B. subtillis, S. aureus, L. inocua, S. Lutea, and M. flavus and Gram-negative: E. coli, P. aeruginosa, S. enteritidis, S. sonnei, K. pneumonia and P. vulgaris bacteria stains were studied using the agar well diffusion and micro-well dilution methods. The concentrations of the wine phenolic compounds: gallic acid, caffeic acid, (+)-catechin, resveratrol, quercetin, quercetin-3-glucoside and malvidin-3-glucoside were determined using HPLC analysis. Results: There was excellent correlation between the contents of gallic acid, caffeic acid, resveratrol, quercetin, quercetin-3-glucoside and malvidine-3-glucoside and the antimicrobial activity of the wines against Gram-positive - C. perfringens and M. flavus (from 0.936 to 0.999) and against Gram-negative bacteria stains - E. coli, P. aeruginosa, S. enteritidis, S. sonnei and P. vulgaris (from 0.904 to 0.999). Furthermore, the content of (+)-catechin has good correlation with the antimicrobial activity of the wines only against L. inocua and P. vulgaris with correlation coefficient of 0.996 and 0.999, respectively. All selected wine phenolic compounds, however, did not show correlation with antimicrobial activity against K. pneumonia strain. Conclusion: The antimicrobial activity of selected Vranac wines indicates that some of the wine's phenolic constituents have the potential to inhibit the growth of certain bacterial strains. © Pharmacotherapy Group, Faculty of Pharmacy, University of Benin, Benin City, 300001 Nigeria. All rights reserved.

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