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91.
A Alimmari DA Mijin R Vuki Evi B Bo I NA Valenti V Vitnik E Vitnik G U Umli 《Chemistry Central journal》2012,6(1):71
ABSTRACT: BACKGROUND: A series of some novel arylazo pyridone dyes was synthesized from the corresponding diazonium salt and 6-hydroxy-4-phenyl-3-cyano-2-pyridone using classical reaction for the synthesis of the azo compounds. RESULTS: The structure of the dyes was confirmed by UV-vis, FT-IR, 1H NMR, 13C NMR spectroscopic technique and elemental analysis. The solvatochromic behaviour of the dyes was evaluated with respect to visible absorption properties in various solvents. CONCLUSIONS: The azo-hydrazone tautomeric equilibration is found to depend upon substituents as well as on solvents. The geometry data of the investigated dyes were obtained using DFT quantum-chemical calculations. The obtained calculational results are in very good agreement with the experimental data. 相似文献
92.
Anife Ahmedova Petja Marinova Gordana Pavlovi? Maya Guncheva Neyko Stoyanov Mariana Mitewa 《Journal of the Iranian Chemical Society》2012,9(3):297-306
A series of seven 2-cinnamoyl-1,3-indandiones and their metal(II) complexes were synthesized and characterized by means of spectroscopic (IR, NMR, electron absorption and emission spectroscopy) and/or single-crystal X-ray diffraction methods. The optical spectra of the organic compounds show very strong absorption in the visible region and weak fluorescence with moderate to strong Stokes shift. The effect of concentration, water addition and metal ion complexation on the optical properties was also studied. In search of potential practical application, the complexation of 2-cinnamoyl-1,3-indandiones with metal(II) ions was investigated. A series of non-charged complexes with Cu(II), Cd(II), Zn(II), Co(II) and Ni(II) was isolated and analyzed by elemental analyses and IR. Most of the complexes show presence of water molecules, most probably coordinated to the metal ion, thus forming octahedral geometry. For the paramagnetic Cu(II) complexes a distorted, flattened tetrahedral structure is proposed, basing on the EPR data. The optical properties of the metal complexes, however, do not differ appreciably from those of the free ligands. 相似文献
93.
Dukovic G Balaz M Doak P Berova ND Zheng M McLean RS Brus LE 《Journal of the American Chemical Society》2006,128(28):9004-9005
We have found that racemic mixtures of chiral single-walled nanotubes (SWNTs) wrapped with d(GT)20 DNA oligomer exhibit circular dichroism (CD). We attribute the CD signal to induced CD arising from the coupling of transition moments of the SWNTs and the DNA. Although the nanotube mixture appears to contain both enantiomers in equal amounts, DNA-SWNT transition moment interaction is more constructive for one SWNT enantiomer over the other, resulting in an overall CD signal. 相似文献
94.
Anita Grozdanov Aleksandra Buzarovska Gordana Bogoeva‐Gaceva Emanuel Nedkov 《Journal of Polymer Science.Polymer Physics》2005,43(1):66-73
The kinetics of nonisothermal melting and the crystallization of polypropylene (PP) in polypropylene/carbon‐fiber (C/PP) composites were studied by differential scanning calorimetry with the Nedkov and Atanasov method. Characteristic parameters such as the lamellar thickness, the transport energy through the phase boundary, and the surface free energy were determined and analyzed. In nonisothermal melting, the nucleation effect of carbon fibers was confirmed by decreasing transport energy (79 and 41 kJ/mol for PP and C/PP, respectively) and surface free energy (8 × 10?4 and 7.9 × 10?5 J/m2 for PP and C/PP, respectively). Depending on the carbon‐fiber content, the lamellar thickness changed from 6.7 × 10?9 m to 9.05 × 10?9 m. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 66–73, 2005 相似文献
95.
Gordana Stojanovic 《Geometriae Dedicata》2006,123(1):1-10
We introduce (k,l)-regular maps, which generalize two previously studied classes of maps: affinely k-regular maps and totally skew embeddings. We exhibit some explicit examples and obtain bounds on the least dimension of a
Euclidean space into which a manifold can be embedded by a (k,l)-regular map. The problem can be regarded as an extension of embedding theory to embeddings with certain non-degeneracy conditions
imposed, and is related to approximation theory. 相似文献
96.
Bigović D Savikin K Janković T Menković N Zdunić G Stanojković T Djurić Z 《Natural product communications》2011,6(6):819-822
Flowers of Helichrysum plicatum were extracted under different experimental conditions, and their antioxidant activity was determined by DPPH radical scavenging assay. Extracts obtained with higher concentration of ethyl acetate (90% or 100%) were found to contain the greatest amount of total phenolics (> 250 mg gallic acid equivalents/g of dried extract), and high correlation between total phenolic content and antiradical activity was observed (r = -0.79). Based on the total phenolic content and antiradical activity, some extracts were selected for investigation of cytotoxic activity toward PC3, HeLa and K562 human cancer cell lines in vitro. All tested extracts exhibited moderate activity against HeLa cells (41.9-42.1 microg/mL), whereas the extract obtained with 100% ethyl acetate was the most active against K562 and PC3 cell lines (25.9 and 39.2 microg/mL, respectively). Statistical analysis revealed significant correlation between total phenolic content and cytotoxic activity against PC3 and K562 cells. HPLC identification of phenolic compounds from the extracts indicated the presence of apigenin, naringenin and kaempferol as free aglycones, and glycosides of apigenin, naringenin, quercetin and kaempferol. Among aglycones, kaempferol displayed moderate cytostatic activity against all cell lines (24.8-64.7 microM). 相似文献
97.
Gordana Pejovi? Jovan Filipovi? Ljiljana Tasi? 《Accreditation and quality assurance》2011,16(4-5):253-261
The primary role of European pharmaceutical legislation is to safeguard public health while encouraging the development of the pharmaceutical industry, creation of single market for pharmaceuticals with removed barriers to medicines trade. This article presents some important characteristics of pharmaceutical legislation in Serbia, the potential EU candidate country, and the latest improvements of existing national pharmaceutical legislation. Additional explanation is given for the Serbian negotiations with World Trade Organization and measures taken for the harmonisation with Agreements on Technical barriers to Trade (TBT), especially with Agreement on Trade-Related Intellectual Property Rights. Current status of Serbian pharmaceutical market is described, with the highlight of domestic manufacturers??capacity to comply with European Union requirements. National medicines agency is described in the framework of European medicines quality infrastructure. The role and responsibility of national medicines authority to assure access to quality, safe and efficacious medicines on Serbian market is described. The special emphasis is given to agency’s role in harmonisation process, in terms of removing unnecessary barriers to medicines trade in Serbia. 相似文献
98.
In this report, we investigated the so-called plasmonic platforms prepared to target ultra-short fluorescence and accurate instrumental response function in a time-domain spectroscopy and microscopy. The interaction of metallic nanoparticles with nearby fluorophores results in the increase of the dye fluorescence quantum yield, photostability and decrease of the lifetime parameter. The mentioned properties of platforms were applied to achieve a picosecond fluorescence lifetime (21 ps) of erythrosin B, used later as a better choice for deconvolution of fluorescence decays measured with “color” sensitive photo-detectors. The ultra-short fluorescence standard based on combination of thin layers of silver film, silver colloidal nanoparticles (about 60 nm in diameter), and top layer of erythrosin B embedded in 0.2 % poly(vinyl) alcohol. The response functions were monitored on two photo-detectors; microchannel plate photomultiplier and single photon avalanche photodiode as a Rayleigh scattering and ultra-short fluorescence. We demonstrated that use of the plasmonic base fluorescence standard as an instrumental response function results in the absence of systematic error in lifetime measurements and analysis. 相似文献
99.
100.
Gordana Stojanović Ivana Zrnzević Ivana Zlatanović Miroslava Stanković Vesna Stankov Jovanović Violeta Mitić 《Natural product research》2020,34(4):549-552
AbstractThe aim of this study was to determine, for the first time, the chemical composition of Peltigera horizontalis thallus and apothecia extracts (ether, ethyl acetate, dichloromethane and acetone) by HPLC-UV and GC-MS, and evaluate activity of genotoxic, anticholinesterase, antioxidant and antibacterial potential of acetone extracts. Major constituents of thallus extracts were gyrophoric acid, and methyl gyrophorate while dominant component of apothecia extracts was tenuiorin. The predominant volatile compounds in extracts were methyl orsellinate, dodecyl acrylate, orcinol and orcinol monomethyl ether. The thallus acetone extract at concentration of 2.0 µg mL?1 gave the greatest decrease in the micronuclei frequency (22.4%) of all tested extracts. Apothecia extract showed stronger antioxidant activity as compared to thallus extract. Tested extracts at concentration of 10?mg mL?1 exhibited inhibitory effect (16.5% for thallus and 12.8% for apothecia) on pooled human serum cholinesterase. P. horizontalis acetone extracts had no activity against the tested five bacteria strains. 相似文献