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Anife Ahmedova Nikola Burdzhiev Samuele Ciattini Elena Stanoeva Mariana Mitewa 《Comptes Rendus Chimie》2010,13(10):1269-1277
The current study describes the synthesis of a new 1,3-indandione derivative with conjugated N-phenylaza-15-crown-5 moiety (4). The crystal structure of compound 4 was solved and its optical properties were studied in various solvents and in presence of alkaline and alkaline-earth metal ions. Quantum chemical (DFT) methods were employed to describe the structure and the optical properties of the studied compound and its complexes. The obtained results indicated that the synthesis of compound 4 using acid-catalyzed aldol reaction between 2-acetyl-1,3-indandione and the corresponding aldehyde is accompanied with an unexpected deacetylation step. In this way, the N-phenylaza-15-crown-5 moiety is directly conjugated with the 1,3-indandione fragment, known as a very strong electron acceptor. Therefore, the absorption spectra of 4 are only slightly influenced by complexation with Ba2+ and Sr2+ ions. 相似文献
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Unequal-sphere packing model is applied for the simulation of large number of hexagonal adlayer structures with surface coverage between theta=13 and theta=1 on the hexagonal substrate, with atomic radius of the adsorbate and substrate atoms as the only input. Each structure is characterized with respect to collective adlayer properties: the average adlayer height and the adlayer roughness. The distribution of hexagonal arrangements is presented in a special plot, which can be used for identification and characterization of hexagonal adlayers of different surface coverages and atomic registries. The most likely structures are related to the extreme values of our model parameters. The usefulness of this methodology is successfully demonstrated by comparison with some real adsorbate-substrate systems, i.e., halogens and rare gases adsorbed on (111) surface. Besides the agreement with experimental results, our model offers new insight into the formation of atomic adlayers and detailed analysis of the atomic registry. We believe that our approach will be of use for identification of probable structures among the large number of combinatorial possibilities in theoretical studies and for better interpretation of experimental results (i.e., scanning-tunneling microscopy images of atomic adlayers). 相似文献
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Nonlinear Dynamics - We consider a two-body problem with quick loss of mass which was formulated by Verhulst (Verhulst in J Inst Math Appl 18: 87–98, 1976). The corresponding dynamical system... 相似文献
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Nešić Nikola Cajić Milan Karličić Danilo Obradović Aleksandar Simonović Julijana 《Nonlinear dynamics》2022,109(3):2003-2012
Nonlinear Dynamics - A (3+1)-dimensional coupled nonautonomous NLS model with partially nonlocal coupled nonlinearities under the linear and harmonic potentials becomes the center of attention. Two... 相似文献
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Kadoić Nikola Ređep Nina Begičević Divjak Blaženka 《Central European Journal of Operations Research》2018,26(3):611-628
Central European Journal of Operations Research - Using the appropriate methodology for strategic decision-making in higher education is crucial to make effective decisions. In this paper, the... 相似文献
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Robert Zona Sonja Solar Nikola Getoff Knud Sehested Jerzy Holcman 《Radiation Physics and Chemistry》2010,79(5):626-636
The reactions of OH radicals with 2-, 3-, 4-chlorobenzoic acids (ClBzA) and chlorobenzene (ClBz), k(OH+substrates)=(4.5?6.2)×109 dm3 mol?1 s?1, have been studied by pulse radiolysis in N2O saturated solutions. The absorption maxima of the OH-adducts were in the range of 320?340 nm. Their decay was according to a second-order reaction, 2k=(1?9)×108 dm3 mol?1 s?1. In the presence of N2O/O2 the formation of peroxyl radicals was detectable for 2-, 4-ClBzA and ClBz, k(OH-adduct+O2)=(2?4)×107 dm3 mol?1 s?1, while this reaction for 3-ClBzA was too slow to be registered. In the presence of N2O the degradation rates induced by gamma radiation were very similar for all chlorobenzoic acids, yet the chloride formation was distinctly higher for 3-ClBzA. In the presence of oxygen the initial degradation of 2-and 4-ClBzA equaled the OH-radical concentration, whereas in case of 3-ClBzA only ~60% of OH led to degradation. The order for the efficiency of dehalogenation was 4->2->3-ClBzA. Several primary radiolytic products could be detected by HPLC. To evaluate the toxicity of final products a bacterial bioluminescence test was carried out. 相似文献