Smelcerovic A.,TU Dortmund |
Smelcerovic A.,University of Niš |
Yancheva D.,Bulgarian Academy of Science |
Cherneva E.,Bulgarian Academy of Science |
And 4 more authors.
Journal of Molecular Structure | Year: 2011
A pathogenic fungus, Fusarium sporotrichioides Sherb., was isolated from Hypericum barbatum Jacq. The volatile compounds of broth and mycelium were analyzed using GC-MS and three cyclodidepsipeptides (dioxomorpholines), 3,6-di(propan-2-yl)-4-methyl-morpholine-2,5-dione, 3-(2-methylpropyl)-6-(propan- 2-yl)-4-methyl-morpholine-2,5-dione and 3-(butan-2-yl)-6-(propan-2-yl)-4-methyl- morpholine-2,5-dione, were found for the first time in the natural products. The structures of the compounds were confirmed by comparison of the analytical data for the natural products with samples obtained via synthetic methods. The conformational features and vibrational spectra of the three cyclodidepsipeptides were characterized by density functional theory (DFT) calculations and IR spectroscopy. The cyclic hexadepsipeptide enniatin B was identified by a LC-MS/MS analysis of the non-volatile products of broth and mycelium. The above-mentioned three cyclodidepsipeptides are probably synthesized using similar biosynthetic ways to enniatin B involving a nonribosomal mechanism. © 2010 Elsevier B.V. All rights reserved.
Nikolic V.,University of Nish |
Ilic D.,University of Nish |
Nikolic L.,University of Nish |
Stankovic M.,University of Nish |
And 4 more authors.
Central European Journal of Chemistry | Year: 2010
The inclusion complex β-cyclodextrin:nifedipin was prepared in solid state by coprecipitation with 1:1 mol ratio. The structure of the obtained complex and nifedipin was characterized by use of X-ray diffraction (XR), infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and differential scanning calorimetry (DSC) methods. The photodegradation of nifedipin and the β-cyclodextrin:nifedipin inclusion complex in solid state was monitored under natural daylight by infrared spectroscopy, whereby the free nifedipin degraded four to five times faster than the complexed nifedipin. The photodegradation products of both free and complexed nifedipin, formed during irradiation at 350 nm (with corresponding energy flux of 18 W m-2) were monitored by liquid chromatography during various time intervals. The speed of formation of nitroso- and nitro-phenyl derivatives by nifedipin irradiation was significantly higher than those of complexed nifedipin irradiation, which indicates its increased photostability in the inclusion complex. The effect on this property is significant because it contributes both to the improvement of the therapeutic effect of nifedipin and to the safer application thereof. © 2010 Versita Warsaw and Springer-Verlag Wien.
Nikolic Z.S.,University of Nish |
Wakai F.,Tokyo Institute of Technology
IOP Conference Series: Materials Science and Engineering | Year: 2011
The rearrangement process during liquid phase sintering has been generally accepted that driven by the capillary forces between solid grains embedded in liquid. This paper outlines a computer-based method for three-dimensional computer simulation of rearrangement during liquid phase sintering. The theoretical models dealing with the fundamental interaction forces that exist between grains attached by liquid bridges will be outlined and the development from these pair-wise interactions to multi-grain models will be described. © 2011 Ceramic Society of Japan.
Glisic S.,University of Nish |
Cakic M.,University of Nish |
Nikolic G.,University of Nish |
Danilovic B.,University of Nish
Journal of Molecular Structure | Year: 2015
Silver nanoparticles (AgNPs-CMD) were synthesized from aqueous solution of silver nitrate (AgNO3) and carboxymethyl dextrane (CMD) in mole ratio 1:1 and 1:2. The characterization of AgNPs-CMD was performed by ultraviolet-visible (UV-VIS) spectroscopy, gel permeation chromatography (GPC), scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and antimicrobial activity. The formation of AgNPs-CMD was screened by color changes of the reaction mixture to yellow, by measuring the surface plasmon resonance absorption peak in UV-VIS region at 420 nm. The GPC chromatography measurement confirmed the formation of AgNPs-CMD. The SEM microscopy was used for size and shape of AgNPs-CMD nanoparticles determination. The presence of elemental silver and crystalline structure of AgNPs-CMD were confirmed by XRD analyses. The possible functional group of CMD responsible for the reduction and stabilization of AgNPs were determinated by FT-IR spectroscopy. The AgNPs-CMD showed strong antibacterial activity against Bacillus lutea, Bacillus aureus, Bacillus cereus, Enterococus fecalis, Pseudomonas aeruginosa, Klebsiella pneumoniae and antifungal activity against Aspergillus spp., Penicillum spp., and Candida albicans. © 2014 Elsevier B.V. All rights reserved.