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121.
Branimir Pavli
ivan Mrkonji Nemanja Tesli Aleksandra Cvetanovi Kljaki Milica Poji Anamarija Mandi Alena Stupar Filipa Santos Ana Rita C. Duarte Aleksandra Mian 《Molecules (Basel, Switzerland)》2022,27(5)
Wild thyme (Thymus serpyllum L.) herbal dust has been recognized as a potential underutilized resource for the recovery of antioxidants. The aim of this paper was to optimize natural deep eutectic solvent (NADES) extraction of polyphenols to obtain improved antioxidant activity of extracts determined by selected in vitro assays (DPPH, FRAP, and ABTS). Twenty different NADES systems were investigated in the first step of the screening of the extraction solvent and l-proline (Pro)–glycerine (Gly) based solvents provided the best results. Preliminary experiments organized by 25−1 fractional factorial design narrowed down the number of extraction factors from five (temperature, extraction time, NADES type, water content and L/S ratio) to three and determined their experimental domain for the final step. A face-centered central composite design with temperature (40–55–70 °C), extraction time (60–120–180 min) and L/S ratio (10–20–30 g NADES/g sample) was applied for influence analysis and process optimization. Multi-response optimization suggested a temperature of 65 °C, time of extraction of 180 min and L/S ratio of 28 g NADES/g DW as optimal extraction parameters. Experimental validation confirmed good agreement between experimental and predicted results in the extract obtained at optimal conditions and the interactions in the most suitable NADES (N16; Pro–Gly–H2O; 1:2:1) were confirmed by the 1H-NMR. 相似文献
122.
123.
Milica Ilić Dietrich Flockerzi Andreas Seidel-Morgenstern 《Journal of chromatography. A》2010,1217(14):2132-2137
A competitive adsorption isotherm model is derived for binary mixtures of components characterized by single component isotherms which are second-order truncations of higher order equilibrium models suggested by multi-layer theory and statistical thermodynamics. The competitive isotherms are determined using the ideal adsorbed solution (IAS) theory which, in case of complex single component isotherms, does not generate explicit expressions to calculated equilibrium loadings and causes time consuming iterations in simulations of adsorption processes. The explicit model derived in this work is based on an analysis of the roots of a cubic polynomial resulting from the set of IAS equations. The suggested thermodynamically consistent and widely applicable competitive isotherm model can be recommended as a flexible tool for efficient simulations of fixed-bed adsorber dynamics. 相似文献
124.
Milutin M. Milosavljevi? Milica Sovrli? Aleksandar D. Marinkovi? Dragan D. Milenkovi? 《Monatshefte für Chemie / Chemical Monthly》2010,57(2):749-755
Abstract
A novel synthesis of N-alkyl and N,N-dialkyl O-ethyl thiocarbamates from diethyl dixanthogenate and primary and secondary amines, using three oxidizing systems, has been developed on the laboratory scale, and the method using sodium hypochlorite has been applied on a semi-industrial scale. The effect of the oxidizing agents, sodium hypochlorite, in-situ-generated peracetic acid, and the manganese(II) acetate/oxygen system on product purity and yield was studied. The results obtained by use of these three methods were compared with those obtained by reaction of sodium ethyl xanthogenacetate and amines, and of sodium ethyl xanthate with amines in the presence of sulfated nickel zeolite catalyst. The reaction mechanism of sodium hypochlorite oxidation has been established on the basis of isolation of reaction intermediates and determination of their structure by use of Fourier-transform infrared, 1H and 13C NMR, and mass spectrometric methods. The suggested sodium hypochlorite and manganese(II) acetate/oxygen systems have many advantages in comparison with commercial and catalytically promoted synthetic methods, because they are new ecologically friendly syntheses. 相似文献125.
Ivanka Holclajtner‐Antunovi Danica Bajuk‐Bogdanovi Vesna Biki Milica Mari‐Stojanovi 《Journal of Raman spectroscopy : JRS》2012,43(8):1101-1110
A selection of Byzantine table pottery (17 samples) dating from the period between the beginning of the 12th century and the first half of the 13th century, discovered at Braničevo in Serbia, were analysed by Fourier transform infrared, micro‐Raman and scanning electron microscopy with energy dispersive spectroscopy and petrography analysis. The aim of the investigation was to determine the chemical and mineralogical composition of the body and of the glaze and thus to determine the production technology. Fourier transform infrared spectroscopy provided data for estimating the firing temperature and the basic mineralogical composition, and micro‐Raman spectroscopy was applied to study and characterise both the glaze and the body of the analysed sherds. It was found that noncalcareous clays, characterised by a rich mineral assemblage, were fired at temperatures between 700 and 900 °C. Oxidizing atmosphere was applied in the production of the red colour pottery. The dark and grey coloured paste of one group of sherds was produced by firing organic matter‐rich clays in a reducing environment. The main type of transparent glaze was identified as lead‐rich, and two samples were alkali–lime glazed. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
126.
Milenković M Warżajtis B Rychlewska U Radanović D Anđelković K Božić T Vujčić M Sladić D 《Molecules (Basel, Switzerland)》2012,17(3):2567-2578
The facile preparation of a racemic hydrazine bridged diphosphonium compound possessing a ring system analogous to bicyclo[3.3.2]decane is reported. Although the reaction yield is low, the structure of the compound, which possesses an eight-membered ring, two phosphonium cationic centers, a biimino bridge, molecular chirality and two fused aromatic rings locked into roughly perpendicular planes is unusual. The compound displays substantial biological activity in the brine shrimp test and cleaves plasmid DNA. 相似文献
127.
Tatjana Davidovi? Milica ?elmi? Du?an Teodorovi? Du?an Ramljak 《Journal of Heuristics》2012,18(4):549-569
The static scheduling of independent tasks on homogeneous multiprocessor systems is studied in this paper. This problem is treated by the Bee Colony Optimization (BCO) meta-heuristic. The BCO algorithm belongs to the class of stochastic swarm optimization methods inspired by the foraging habits of bees in nature. To investigate the performance of the proposed method extensive numerical experiments are performed. Our BCO algorithm is able to obtain the optimal value of the objective function in the majority of test examples known from literature. The deviation of non-optimal solutions from the optimal ones in our test examples is at most 2%. The CPU times required to find the best solutions by BCO are significantly smaller than the corresponding times required by the CPLEX optimization solver. Moreover, our BCO is competitive with state-of-the-art methods for similar problems, with respect to both solution quality and running time. The stability of BCO is examined through multiple executions and it is shown that solution deviation is less than 1%. 相似文献
128.
Milorad Stojanovic Nicholas J. Robinson Tu Ngo Richard E. Sykora 《Journal of chemical crystallography》2011,41(10):1425-1432
Abstract
Three novel compounds have been synthesized and structurally characterized: [1,10-Hphen]2Pt(CN)4·2H2O (1a) space group P21/n, a = 8.73070(17) ?, b = 15.4609(2) ?, c = 9.82661(19) ?, β = 103.252(2)°; [2,2′-Hbipy]2Pt(CN)4·2H2O (1b) space group P21/n, a = 7.0859(14) ?, b = 12.940(2) ?, c = 13.7486(19) ?, β = 100.708(16)°; K2[Pt(CN)4]·2phen (phen = 1,10-phenanthroline) (2) space group P21/c, a = 8.1393(4) ?, b = 20.4050(9) ?, c = 8.4085(4) ?, β = 105.284°. All three structures contain isolated [Pt(CN)4]2− ions and they all illustrate the absence of Pt⋯Pt interactions due to the presence of bulky cyclic amines or ammoniums. The structures of 1a and 1b contain large organic cations, 2,2′-bipyridinium and 1,10-phenanthrolinium, respectively while compound 2 contains neutral 1,10-phenanthroline molecules co-crystallized between the potassium tetracyanoplatinate framework. 相似文献129.
Johnsson P Rouzée A Siu W Huismans Y Lépine F Marchenko T Düsterer S Tavella F Stojanovic N Redlin H Azima A Vrakking MJ 《Optics letters》2010,35(24):4163-4165
We report on the implementation of a high-count-rate charged particle imaging detector for two-color pump-probe experiments at the free electron laser in Hamburg (FLASH). In doing so, we have developed a procedure for finding the spatial and temporal overlap between the extreme UV free electron laser (FEL) pulses and the IR pulses, which allows for complete alignment of the setup in situations where the region of overlap between the FEL and the IR is not easily accessible by means of imaging optics. 相似文献
130.