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Jesús Emmanuel Solís‐Prez Jos Francisco Gmez‐Aguilar Lizeth Torres Ricardo Fabricio Escobar‐Jimnez Juan Reyes‐Reyes 《Mathematical Methods in the Applied Sciences》2019,42(18):7335-7348
In this work, the design of spectral observers for signal reconstruction based on Kalman filters is performed and evaluated. The conformable derivative and the beta‐derivative were used to design the Kalman filters. Both derivatives satisfy the same formulas of the classical derivation, eg, the chain rule. The derivative order, the Ricatti equation parameters, and the observers tuning parameters were optimized using an optimization algorithm based on the bat's echolocation behavior (Bat algorithm). The simulation results showed the advantages of using the proposed observers for the signal reconstruction. 相似文献
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Fabricio R. Bisogno Rosario Fernndez Jose María Lassaletta Gonzalo de Gonzalo 《Molecules (Basel, Switzerland)》2021,26(2)
Room temperature ionic liquids (RTILs) have been widely used as (co)solvents in several catalytic processes modifying, in most of the cases, the catalyst activity and/or the selectivity for the studied reactions. However, there are just a few examples of their use in hydrogen bonding organocatalysis. In this paper, we show the positive effect of a set of imidazole-based ionic liquids ([bmim]BF4 and [hmim]PF6) in the enantioselective addition of formaldehyde tert-butylhydrazone to prochiral α-keto esters catalyzed by a sugar-based chiral thiourea. Reactions performed in the presence of low percentages of RTILs led to an increase of the catalyst activity, thereby making possible to work at lower temperatures. Thus, the chiral tert-butyl azomethyl tertiary alcohols could be obtained with moderate to good conversions and higher enantioselectivities for most of the studied substrates when using up to 30 vol% of [hmim]PF6 as a cosolvent in processes performed in toluene. 相似文献
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Modeling the Dynamics of the Xylene Soluble Fraction (XS) in a Bulk Propylene Polymerization Process
A model is built to describe the dynamic trajectories of the xylene soluble fraction (XS) in an industrial bulk propylene polymerization process. Emphasis is given to the coupling between the XS dynamics and the reactor liquid bleed policy. It is shown that cocatalyst recirculation can affect the dynamics of the cocatalyst/donor ratio and consequently the dynamics of XS during polymerization. Simulation results indicate that the effect of the reactor liquid bleed operation and of the cocatalyst/donor ratio upon the XS trajectories can be minimized if PI controllers are designed to control the propane concentration and to increase the speed of the cocatalyst/donor transitions. Finally, it is shown that the model is able to reproduce the dynamic XS profile obtained during a large XS transition at plant site.
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Fabricio M. Gomes Grazielle S. Silva Daltro G. Pinatti Rosa A. Conte Heizir F. de Castro 《Applied biochemistry and biotechnology》2005,121(1-3):255-268
The objective of this work was to select an efficient methodology for preparing active samples of Candida rugosa lipase immobilized in wood cellulignin, to be applied in hydrolysis and ester reactions. For this purpose, lipase was immobilized
in the matrix by physical adsorption (pure cellulignin) and covalent binding (activated cellulignin with glutaraldeyde or
carbonyldiimidazole [CDI]) in the presence or absence of polyethylene glycol (PEG) (Molecular mass of 1500 Daltons) as stabilizing
agent. The activating agent and the presence of PEG-1500 in the immobilization procedure showed a strong influence on enzyme
retention in the support. The values for enzyme retention ranged from 20 to 68%, and the highest yield was obtained when the
enzyme was immobilized in cellulignin activated with CDI in the presence of PEG-1500. This immobilized derivative presented
high hydrolytic (193.27 μM/[mg·min]) and synthetic (522.92 μM/[g·min]) activities when compared with those obtained by other techniques. The superiority of this immobilized system was
confirmed by additional analyses, such as infrared spectroscopy and elemental analysis, which demonstrated an appropriate
enzyme fixation and the highest level of protein incorporation in the support. Further information on the immobilized derivative
was obtained by assessing the recycle potential in both aqueous and nonaqueous media. 相似文献
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The preparation of 5-hydroxy-4-nitroso- and 7-hydroxy-4-nitrosobenzofurazan as well as of their 6-chloro and methyl derivatives is described and the oxime structure of these compounds is established. NMR spectra of benzofurazan-4,5-dione-4-monoxime and benzofurazan-4,7-dione-4-monoxime show evidence for an interconversion, in solution, of two monoximes, the 4,5- and 4,7-derivative prevailing in organic solvents and aqueous alkaline media, respectively. Chloro and methyl derivatives of benzofurazan-4,5- and 4,7-dione-4-monoximes show a similar interconversion in organic solvents. 相似文献
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A set of phenethylamines has been successfully prepared via Suzuki-Miyaura cross-coupling of diverse potassium beta-aminoethyltrifluoroborates with aryl halides. The potassium beta-aminoethyltrifluoroborates were easily prepared via hydroboration of enamine and enamide precursors. [reaction: see text]. 相似文献
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Andrés J Feliz M Fraxedas J Hernandez V López-Navarrete JT Llusar R Sauthier G Sensato FR Silvi B Bo C Campanera JM 《Inorganic chemistry》2007,46(6):2159-2166
X-ray structural data for the cubane-type clusters [Mo3CuS4(dmpe)3Cl4](+) and Mo3NiS4(dmpe)3Cl4 (dmpe = 1,2-bis(dimethylphosphino)ethane) with 16 metal electrons have been compared with optimized structural parameters calculated using "ab initio" methodologies. Compound Mo3NiS4(dmpe)3Cl4 crystallizes in the cubic noncentrosymmetric space group P213 with a Mo-Ni distance of 2.647 Angstrom, that is 0.2 Angstrom shorter than the Mo-Cu bond length in the isoelectronic copper cluster. The best agreement between theory and experiments has been obtained using the B3P86 method. In order to validate the B3P86 results, accurate infrared and Raman spectra have been acquired and the vibrational modes associated to the cubane-type Mo3M'S4 (M' = Cu or Ni) unit have been assigned theoretically. The electronic changes taking place when incorporating the M' into the Mo3S4 unit have been analyzed from a theoretical and experimental perspective. The bond dissociation energies between M'-Cl and Mo3S4 fragments show that formation of [Mo3CuS4(dmpe)3Cl4](+) is 135 kcal/mol energetically less favorable than the Ni incorporation. The more robust nature of the Mo3NiS4 fragment has been confirmed by mass spectrometry. The X-ray photoelectron spectroscopy (XPS) spectra of the trimetallic and tetrametallic complexes have been measured and the obtained binding energies compared with the computed electronic populations based on topological approaches of the electron localization function (ELF). The energies and shapes of the Cu 2p and Ni 2p lines indicate formal oxidation states of Cu(I) and Ni(II). However, the reductive addition of nickel into [Mo3S4(dmpe)3Cl3](+) causes a small decrease in the Mo 3d binding energies. This fact prevents an unambiguous assignment of an oxidation state in a conventional way, a circumstance that has been analyzed through the covariance of the electronic populations associated to the C(M') core and V(Mo3Ni) and V(S(2)') valence basins where Mo3NiS4 is a particularly electronically delocalized chemical entity. 相似文献