The Ag nano-structured thin films prepared on flat glass substrates have been studied. The ball-like silver nanoparticles have been synthesized in large quantity by using a modified method of hydrolytic decomposition of silver complexes with amino types ligands formed in ethanol aqueous solution. SEM analysis revealed that Ag nanoparticles are all sphere shaped with bimodal size (40 and 70 nm) distribution. The results of XRD powder pattern examination show that Ag nanoparticles are pure phase, well crystallized. The unit cell dimensions measured on synthesized Ag nano films show small but frequent contraction in comparison to Ag metal standard
Abstract:The aim of this work is to assess damage to the City of Belgrade caused by the unfavorable weather condition of hail due to the absence of anti-hail defense of the city, and to argumentatively point out the necessity of introducing new technical-technological systems for preventing the effects of adverse weather conditions. The results are based on the direct correlation-analyses of two real unfavorable weather events and the estimated financial damage caused by these events. The overall calculation also takes into account financial investments (new financial model) necessary to establish two essentially different systems for anti-hail protection. The damage caused by the hail on the territory of the City of Belgrade and the financial investment in anti-hail protection to reduce it are empirically established for the first time. It is shown how the damage could be transformed to profit, as the financial investment in anti-hail protection is lower than the damage that hail can cause.
In this study, the first complexes of Zn(II) with the N-benzyloxycarbonyl-S-alaninato ligand (N-Boc-S-ala) were synthesized. The new complexes were characterized by elemental analysis, conductometric measurements, IR, 1 H-NMR, 13 C-NMR and 2D-NMR spectroscopy. On the basis of the experimental data, tetrahedral geometry of the Zn(II) complexes was proposed. A very good agreement between the NMR and DFT calculated data was obtained. Investigation of antimicrobial activity of the newly synthesized complexes was also performed. It was established that [Zn(N-Boc-S-ala) 2 ] was selective and acts only on Candida albicans.
Three new binuclear Co(II) mixed-ligand complexes with N,N′,N′′,N′′′-tetrakis(2-pyridylmethyl)-1,4,8,11-tetraazacyclotetradecane (tpmc) and mono-or dicarboxylate ligands were prepared and some of their physical properties were determined. The general formulas: [Co 2 (HCOO) 2 tpmc](ClO 4 ) 2 ·4H 2 O, [Co 2 (CH 3 COO) 2 tpmc](ClO 4 ) 2 and [Co 2 (tpht)tpmc](ClO 4 ) 2 ·4H 2 O (tphtH 2 = terephthalic acid) were proposed on the basis of elemental analyses (C,H,N) and molar conductivity. UV/Vis absorption and IR spectra, magnetic and CV measurements were used to study their geometries and properties. For the monocarboxylate complexes, an exo coordination of Co(II) with four nitrogens from tpmc and bis-bidentate bonded HCOO -/CH 3 COO -in the trans position is assumed. Tpmc adopts the chair conformation. For the dicarboxylate complex, it is supposed that a terephthalate dianion, as well as methylene chains from cyclam bridge two Co(II) atoms, while tpmc is in the boat conformation. The complexes were stable against chemical and electrochemical oxidation of Co(II) to Co(III). The data are compared with those for the previously published Cu(II) complexes containing the corresponding ligands and mutual similarities or differences were considered. Finally, some antibacterial activity of the complexes was found.
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