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1.
Kleandrova Valeria V. Rojas-Vargas Julio A. Scotti Marcus T. Speck-Planche Alejandro 《Molecular diversity》2022,26(5):2523-2534
Molecular Diversity - Hypertension is a medical condition that affects millions of people worldwide. Despite the high efficacy of the current antihypertensive drugs, they are associated with... 相似文献
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In this paper we study a Ginzburg–Landau model which describes the behaviour of a superconducting material including thermal effects. We extend the traditional formulation of the problem, by introducing the temperature as an additional state variable. Accordingly, together with the Gor’kov–Eliashberg system, we introduce an evolution equation for the absolute temperature. We examine in detail the case which allows only variations of the concentration of superconducting electrons and of the temperature, neglecting the electromagnetic field. For this problem existence and uniqueness of the solution are shown. Finally we analyze the asymptotic behaviour of the solutions, proving that the system possesses a global attractor. 相似文献
4.
Ivan Nunes da Silva Wagner Caradori do AmaralLucia Valeria de Arruda 《Applied Mathematical Modelling》2007
This paper presents an efficient approach based on recurrent neural network for solving nonlinear optimization. More specifically, a modified Hopfield network is developed and its internal parameters are computed using the valid subspace technique. These parameters guarantee the convergence of the network to the equilibrium points that represent an optimal feasible solution. The main advantage of the developed network is that it treats optimization and constraint terms in different stages with no interference with each other. Moreover, the proposed approach does not require specification of penalty and weighting parameters for its initialization. A study of the modified Hopfield model is also developed to analyze its stability and convergence. Simulation results are provided to demonstrate the performance of the proposed neural network. 相似文献
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The electrochemical behavior and amperometric-FIA quantification of minoxidil at a glassy carbon electrode is described. The procedure is based on electrochemical oxidation at 0.800 V (vs. Ag/AgCl/NaCl(3 M) in a phosphate buffer solution. Minoxidil was determined over the range 1 x 10(-7) - 1 x 10(-4) M. Different analytical parameters and electrode stability were analyzed to obtain the best electrode performance. The optimal conditions were: working potentials, 0.800 V; flow rate, 0.74 mL min(-1); and solution pH 7.0. This system allowed a sampling rate of 120 samples per hour without any pretreatment. The proposed method was used for minoxidil quantification in pharmaceutical preparations with satisfactory results. The accuracy of FIA-amperometric method was established by a comparison with the conventional UV determination technique using a paired t-test indicating the absence of systematic errors. 相似文献
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Jang SS Lin ST Cagin T Molinero V Goddard WA 《The journal of physical chemistry. B》2005,109(20):10154-10167
We propose a new material consisting of a dendrion copolymer formed from (a) a water-soluble dendritic polymer and (b) a hydrophobic backbone. Using molecular dynamics simulations techniques, we determine the structure and dynamics of the dendrion formed by second-generation Fréchet polyaryl ethereal dendrimer as the hydrophilic component and linear polytetrafluoroethylene (PTFE) as the hydrophobic polymer, with 5 and 10 wt % of water. We find that this material produces a well-developed nanoscale structure in which water forms a continuous nanophase, making this new family of compounds promising candidates for applications in fuel cell membranes. We find that the water molecules are incorporated into the dendrimer block of the copolymer to form a nanophase-segregated structure. The well-developed nanophase-segregated structures rendered by this material have characteristic dimensions of segregation ( approximately 30 Angstrom) and dendrimer conformational properties that are independent of water content. Calculations of water dynamics and proton transport in these nanophase-segregated structures indicate that the dendrion copolymer membrane with 10 wt % of water content has a water structure and transport properties equivalent to that of the hydrated Nafion membrane with 20 wt % of water content. 相似文献
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Nardi L 《Journal of chromatography. A》2003,985(1-2):39-45
Partition coefficients of benzene, toluene, ethylbenzene and xylenes (BTEX), between crosslinked polydimethylsiloxane and water, were determined at room temperature by capillary extraction (a form of in-tube solid-phase microextraction, SPME) coupled to open tubular gas chromatography (in-tube SPME-high-resolution GC). A series of 7-9 repetitive extractions, performed on a 1-ml volume of diluted aqueous BTEX sample by the double-syringe squeeze method, gave exponential regression curves which fit very well with those predicted by partition theory. From the equations of the curves of relative FID response vs. extraction number, experimental Kd were easily calculated and the results compared with literature values. The whole measurement requires about 1 h from the start of the experiment to the final calculation of all BTEX partition coefficients. In-tube SPME resulted in a fast, clean, efficient, and cheaper alternative than the classic 1-cm, externally coated, SPME fiber-holder technique. 相似文献
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Di Bussolo V Caselli M Romano MR Pineschi M Crotti P 《The Journal of organic chemistry》2004,69(21):7383-7386
The reaction of alpha vinyl oxirane 5, prepared through a new route to the d-gulal system, with O-nucleophiles (alcohols and di-O-isopropylidene-alpha-d-monosaccharides) and C-nucleophiles (lithium alkyls) affords, in a completely stereoselective way, the corresponding 2-unsaturated alpha O- and C-glycosides having the same configuration as the starting epoxide. 相似文献
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Photoaffinity labeled (3-diazoacetoxy)-9-cis-retinal (1) and (9-methylenediazoacetoxy)-9-cis-retinal (20) were synthesized and bound to absorption maxima at 465 and 460 nm respectively. Binding studies established that synthetic retinals 1 and 2 bind to the natural binding site and that the integrity of the diazoacetoxy photoaffinity label is preserved in the process. Incorporation of 3-(O14COCHN2)-labeled 9-cis retinal could be conveniently carried out in high yield using apomembrane solubilized in CHAPS as detergent to afford the pigment analog in a pure form. Photolysis of the diazoacetoxy group within the binding site led to 15–20%, crosslinking of rhodopsin as estimated by using radiocarbon containing labeled retinal 1 thus showing that this synthetic retinal is suitable for photoaffinity labeling of the active site in rhodopsin. Subsequent experiments to establish the site(s) of crosslinking by sequencing studies will then contribute to our knowledge of the structure of rhodopsin. 相似文献