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361.
Miloš Kostić Miljana Radović Jelena Mitrović Milan Antonijević Danijela Bojić Milica Petrović Aleksandar Bojić 《Journal of the Iranian Chemical Society》2014,11(2):565-578
Chemically modified Lagenaria vulgaris shell was applied as a new sorbent for the removal of lead (II) ions from aqueous solution in a batch process mode. The influence of contact time, initial concentration of lead (II) ions, initial pH value, biosorbent dosage, particle size and stirring speed on the removal efficiency was evaluated. Biosorbent characterization was performed by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX). Four kinetic models (pseudo-first order, pseudo-second order, Elovich model and Intraparticle diffusion model) were used to determine the kinetic parameters. The experimental results were fitted to the Langmuir, Freundlich, Dubinin–Radushkevich and Temkin models of isotherm. Pseudo-second order kinetic model and Langmuir isotherm model best fitted the experimental data. Sorption process is obtained to be fast and equilibrium was attained within 40 min of contact time. The maximum sorption capacity was 33.21 mg g?1. Biosorption was highly pH-dependent where optimum pH was found to be 5. The results of FTIR and SEM analysis showed the presence of new sulfur functional groups. This study indicated that xanthated Lagenaria vulgaris shell could be used as an effective and low-cost biosorbent for the removal of lead (II) ions from aqueous solution. 相似文献
362.
Vorslova Svetlana Golushko Jelena Galushko Sergey Viksna Arturs 《Chromatographia》2014,78(13):899-908
Application of the solvatic retention model of reversed-phase liquid chromatography was studied to predict retention of phenylisothiocyanate derivatives of amino acids from structural formulae and stationary and mobile phase properties. The gradient elution mode with methanol and acetonitrile aqueous mobile phases was used. It was shown that practically acceptable prediction or retention time values can be achieved after the first approximation step when experimental data of one run are used. The zero approximation level predictions—from structural formulae, column and mobile phase properties can be used as a “first guess” method from which further optimization can begin.
相似文献363.
Dr. Slavko Radenković Jelena Tošović Prof. Remco W. A. Havenith Prof. Patrick Bultinck 《Chemphyschem》2015,16(1):216-222
The effect of benzo and benzocyclobutadieno annelation on the current density induced in a series of biphenylene derivatives is examined at the B3LYP/cc‐pVDZ level of theory, by using the CTOCD‐DZ method. Angular benzo annelation increases, whereas linear benzo annelation decreases the intensity of paratropic (antiaromatic) current density along the four‐membered ring of biphenylene. The opposite effect is found for benzocyclobutadieno annelation. It is shown that the extent of local aromaticity of the four‐membered ring in biphenylene congeners can vary from highly antiaromatic to nonaromatic, as a result of different modes of annelation. 相似文献
364.
Dejan Poleti Jelena Rogan Marko V. Rodi Lidija Radovanovi 《Acta Crystallographica. Section C, Structural Chemistry》2015,71(2):110-115
The novel polymeric complexes catena‐poly[[diaquamanganese(II)]‐μ‐2,2′‐bipyrimidine‐κ4N1,N1′:N3,N3′‐[diaquamanganese(II)]‐bis(μ‐terephthalato‐κ2O1:O4)], [Mn2(C8H4O4)2(C8H6N4)(H2O)4]n, (I), and catena‐poly[[[aquacopper(II)]‐μ‐aqua‐μ‐hydroxido‐μ‐terephthalato‐κ2O1:O1′‐copper(II)‐μ‐aqua‐μ‐hydroxido‐μ‐terephthalato‐κ2O1:O1′‐[aquacopper(II)]‐μ‐2,2′‐bipyrimidine‐κ4N1,N1′:N3,N3′] tetrahydrate], {[Cu3(C8H4O4)2(OH)2(C8H6N4)(H2O)4]·4H2O}n, (II), containing bridging 2,2′‐bipyrimidine (bpym) ligands coordinated as bis‐chelates, have been prepared via a ligand‐exchange reaction. In both cases, quite unusual coordination modes of the terephthalate (tpht2−) anions were found. In (I), two tpht2− anions acting as bis‐monodentate ligands bridge the MnII centres in a parallel fashion. In (II), the tpht2− anions act as endo‐bridges and connect two CuII centres in combination with additional aqua and hydroxide bridges. In this way, the binuclear [Mn2(tpht)2(bpym)(H2O)4] entity in (I) and the trinuclear [Cu3(tpht)2(OH)2(bpym)(H2O)4]·4H2O coordination entity in (II) build up one‐dimensional polymeric chains along the b axis. In (I), the MnII cation lies on a twofold axis, whereas the four central C atoms of the bpym ligand are located on a mirror plane. In (II), the central CuII cation is also on a special position (site symmetry ). In the crystal structures, the packing of the chains is further strengthened by a system of hydrogen bonds [in both (I) and (II)] and weak face‐to‐face π–π interactions [in (I)], forming three‐dimensional metal–organic frameworks. The MnII cation in (I) has a trigonally deformed octahedral geometry, whereas the CuII cations in (II) are in distorted octahedral environments. The CuII polyhedra are inclined relative to each other and share common edges. 相似文献
365.
Marina Krvavica Dario Lasi Jasenka Gajdo Kljusuri Jelena ugum piro Janovi Sran Milovac Jasna Bonir 《Molecules (Basel, Switzerland)》2021,26(14)
Chemical characteristics of raw and processed Istarski pršut (PDO) produced from two different pig genotypes were studied with special emphasis on amino and fatty acid composition and factors of lipid stability. Raw hams of Large White (LW)xLandrace (L), and (LWxL)xDuroc (D) pig genotypes were used in the study (20 hams of each genotype). All left raw hams from each carcass were processed in accordance with the PDO specification of Istarski pršut, and other half (the right ones) of LWxL)xD genotype were used for analyses of raw hams (fresh muscles). Istarski pršut was evaluated on the basis of the chemical parameters of the raw and matured lean ham. The process of dry curing significantly influenced the chemical properties of Istarski pršut. Despite the higher content of intramuscular fat and polyunsaturated fatty acids, the fat of (LWxL)xD ham was much more resistant to hydrolysis and oxidation, suggesting that fatty acid profile and other factors, also play a significant role. Significant differences between pig genotypes in the amino acid and fatty acid profiles were found. The analyzed Istarski pršut may be distinguished by prints of multivariate chemometric statistical analysis, based on their amino acid and fatty acid compositions. 相似文献
366.
Jaroslav Jaroš Kusano Takaŝi Jelena Manojlović 《Central European Journal of Mathematics》2013,11(12):2215-2233
Positive solutions of the nonlinear second-order differential equation $(p(t)|x'|^{\alpha - 1} x')' + q(t)|x|^{\beta - 1} x = 0,\alpha > \beta > 0,$ are studied under the assumption that p, q are generalized regularly varying functions. An application of the theory of regular variation gives the possibility of obtaining necessary and sufficient conditions for existence of three possible types of intermediate solutions, together with the precise information about asymptotic behavior at infinity of all solutions belonging to each type of solution classes. 相似文献
367.
368.
Jelena Kati? 《Differential Geometry and its Applications》2005,22(2):215-227
We study the intersections of gradient trajectories and holomorphic discs with Lagrangian boundary conditions in cotangent bundles, and give a construction of Piunikhin-Salamon-Schwarz isomorphisms in Lagrangian intersections Floer homology. 相似文献
369.
Snezana D Nikolic Jelena J Mutic Aleksandar D Lolic Dragan D Manojlovic 《Analytical sciences》2005,21(5):525-529
A rapid, selective, and sensitive kinetic flow-injection method for iodide content determination with amperometric detection on a platinum electrode was developed. The method is based on the catalytic effect of iodide on the Mn3+ reaction with As3+ in the presence of sulfuric acid. The calibration curve was linear in the concentration range from 5.0 x 10(-7) to 1.0 x 10(-4) mol/L iodide. The limit of detection (LOD) was found to be 5.0 x 10(-9) mol/L iodide. The relative standard deviations (RSD) were 1.68% and 3.03% for 1.0 x 10(-3) mol/L standard and 1.0 x 10(-6) mol/L iodide solution (n = 6), respectively. The method has been successfully applied for determination of iodide in waters, table salts, fodder, organic substances and human blood sera. The results were compared with those obtained by a standard AOAC (Association of Official Analytical Chemists) method, as well as with those obtained by a kinetic spectrophotometric procedure for determination of iodide. 相似文献
370.