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241.
O Romero M Filice Bde L Rivas C Carrasco-Lopez J Klett A Morreale JA Hermoso JM Guisan O Abian JM Palomo 《Chemical communications (Cambridge, England)》2012,48(72):9053-9055
An efficient chemoselective method for the creation of semisynthetic lipases by site-specific incorporation of tailor-made peptides on the lipase-lid site was developed. These new enzymes showed excellent improved specificity and regio- or enantioselectivity in different biotransformations. 相似文献
242.
Beatriz Abad‐García Sergio Garmón‐Lobato Luis A. Berrueta Blanca Gallo Francisca Vicente 《Rapid communications in mass spectrometry : RCM》2009,23(17):2785-2792
A mass spectrometric method using electrospray ionization with triple quadrupole and quadrupole time‐of‐flight hybrid (Q‐Tof) mass spectrometry has been applied to the structural characterization of dihydroflavonols. This family of compounds has been studied by liquid chromatography/tandem mass spectrometry (LC/MS/MS) for the first time in this work. A comprehensive study of the product ion MS spectra of the [M+H]+ ion of a commercially available standard has been performed. The most useful fragmentations in terms of structural identification are those that involve cleavage of the C‐ring, resulting in diagnostic ions of dihydroflavonol family: 1,3A, 1,2B, 1,2B‐CO, 0,2A, 0,2A‐H2O, 0,2A‐CO, and 0,2A‐H2O‐CO, that allow the characterization of the substituents in the A‐ and B‐rings. In addition to those ions, other product ions due to losses of H2O and CO molecules from the Y ion were observed. Their fragmentation mechanisms and ion structures have been proposed. The established fragmentation patterns have been used to successfully identity three dihydroflavonols found in tangerine juices for the first time. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
243.
Adaptive numerical algorithms in space weather modeling 总被引:1,自引:0,他引:1
Gábor Tóth Bart van der Holst Igor V. Sokolov Darren L. De Zeeuw Tamas I. Gombosi Fang Fang Ward B. Manchester Xing Meng Dalal Najib Kenneth G. Powell Quentin F. Stout Alex Glocer Ying-Juan Ma Merav Opher 《Journal of computational physics》2012,231(3):870-903
Space weather describes the various processes in the Sun–Earth system that present danger to human health and technology. The goal of space weather forecasting is to provide an opportunity to mitigate these negative effects. Physics-based space weather modeling is characterized by disparate temporal and spatial scales as well as by different relevant physics in different domains. A multi-physics system can be modeled by a software framework comprising several components. Each component corresponds to a physics domain, and each component is represented by one or more numerical models. The publicly available Space Weather Modeling Framework (SWMF) can execute and couple together several components distributed over a parallel machine in a flexible and efficient manner. The framework also allows resolving disparate spatial and temporal scales with independent spatial and temporal discretizations in the various models.Several of the computationally most expensive domains of the framework are modeled by the Block-Adaptive Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) code that can solve various forms of the magnetohydrodynamic (MHD) equations, including Hall, semi-relativistic, multi-species and multi-fluid MHD, anisotropic pressure, radiative transport and heat conduction. Modeling disparate scales within BATS-R-US is achieved by a block-adaptive mesh both in Cartesian and generalized coordinates. Most recently we have created a new core for BATS-R-US: the Block-Adaptive Tree Library (BATL) that provides a general toolkit for creating, load balancing and message passing in a 1, 2 or 3 dimensional block-adaptive grid. We describe the algorithms of BATL and demonstrate its efficiency and scaling properties for various problems.BATS-R-US uses several time-integration schemes to address multiple time-scales: explicit time stepping with fixed or local time steps, partially steady-state evolution, point-implicit, semi-implicit, explicit/implicit, and fully implicit numerical schemes. Depending on the application, we find that different time stepping methods are optimal. Several of the time integration schemes exploit the block-based granularity of the grid structure.The framework and the adaptive algorithms enable physics-based space weather modeling and even short-term forecasting. 相似文献
244.
Carlos Elvira Beln Levenfeld Blanca Vzquez Julio San Romn 《Journal of polymer science. Part A, Polymer chemistry》1996,34(13):2783-2789
Two tertiary amines with a chemical structure rather similar to dimethyl-4-toluidine have been prepared and tested as activators for the free radical polymerization of methyl methacrylate. 4-Dimethylaminobenzyl alcohol, DMOH, was synthesized by reduction of the corresponding benzaldehyde. 4-Dimethylaminobenzyl methacrylate, DMMO, was synthesized by condensation of methacryloyl chloride with DMOH in the presence of triethylamine as catalyst. Kinetic studies of the bulk polymerization of methyl methacrylate initiated by the redox system BPO–amine have been carried out by differential scanning calorimetry at different temperatures in the interval 30–40°C. An increase of the overall rate constant, k, with increasing temperature was observed for all redox systems. The system BPO/DMT gave the highest values of k. The polymerizations catalyzed by DMOH and DMMO respectively gave lower values of the overall Arrhenius activation than that obtained with DMT. DMMO may participate in the polymerization not only as activator but also as an acrylic derivative which can be incorporated into the polymeric growing chains during the propagation step of the free radical polymerization. © 1996 John Wiley & Sons, Inc. 相似文献
245.
Felipe Gómez-de la Torre Yolanda Gutiérrez Félix A. Jalón Blanca R. Manzano Ana Rodríguez 《Monatshefte für Chemie / Chemical Monthly》2000,131(12):1267-1280
Summary. Partial removal of chloride anions from the dimer [Pd(η3-2-CH3*C3H4)(μ-Cl)]2 with AgTf(Tf = CF3SO3) followed by addition of dppm affords [Pd2(η3-Me*C3H4)2(μ-Cl)(μ-dppm)]Tf (1). The substitution of Cl− by X− (X = pz, SC6F5, S
py
) using the appropriate salts yields the new derivatives [Pd2(η3-Me*C3H4)2(μ-X)(μ-dppm)]Tf (2–4). All complexes exhibit a dinuclear half-A-frame structure with two isomers present in solution. The isomers differ in the
relative orientation of the two allyl groups (cis or trans). The isomer interconversion was studied by variable temperature 1H NMR spectroscopy. The molecular structures of 2 and 4 were solved by X-ray diffraction studies. A distorted boat conformation of the seven- or six-membered metallacycle was found
in both cases.
Received June 7, 2000. Accepted June 20, 2000 相似文献
246.
Anna D. Ilyina José L. Martínez Hernández Blanca H. López Luján Juan E. Mauricio Benavides Jorge Romero García Jesús Rodríguez Martínez 《Applied biochemistry and biotechnology》2000,88(1-3):45-58
Enhanced chemiluminescence (ECL) describes the phenomenon of the light output increase in the reaction of oxidation of luminol
catalyzed by horseradish peroxidase (HRP) in the presence of certain phenolic compounds. This work summarizes the effects
of preincubation of certain substances with HRP on the chemiluminescent reaction intensity. Preincubation of herbicide, detergent,
surfactants (Brij-96 and Tween-20), phenol, metal ions (mercury, cobalt, and nickel), and bactericide with HRP had an inhibitory
effect on the enzyme activity. HRP-preincubation with metal ions (cadmium, magnesium, and zinc), as well as with some insecticides,
stimulated the chemiluminescent intensity. Calibration graphs were obtained to demonstrate the possibility to determine the
pollutant concentration. Light emission from the peroxidase catalyzed enhanced chemilum inescence is affected by a wide number
of chemicals and, therefore, the method can beused for on-site monitoring of water quality. A rapid and simple assay to detect
water contamination has been developed. 相似文献
247.
Reinier Lemos Dr. Kamil Makowski Dr. Luis Almagro Dr. Blanca Tolón Dr. Hortensia Rodríguez Dr. M. Ángeles Herranz Dr. Dolores Molero Prof. Dr. Nazario Martín Prof. Dr. Margarita Suárez 《European journal of organic chemistry》2023,26(7):e202201301
Cyclopropanation reactions between C60 and different malonates decorated with monosaccharides and steroids using the Bingel-Hirsch methodology have allowed the obtention of a new family of hybrid compounds in good yields. A complete set of instrumental techniques has allowed us to fully characterize the hybrid derivatives and to determine the chemical structure of monocycloadducts. Besides, the proposed structures were investigated by cyclic voltammetry, which evidenced the exclusive reductive pattern of fullerene Bingel-type monoadducts. Theoretical calculations at the DFT-D3(BJ)/PBE 6-311G(d,p) level of the synthesized conjugates predict the most stable conformation and determine the factors that control the hybrid molecules′ geometry. Some parameters such as polarity, lipophilicity, polar surface area, hydrophilicity index, and solvent-accessible surface area were also estimated, predicting its potential permeability and capability as cell membrane penetrators. Additionally, a molecular docking simulation has been carried out using the main protease of SARS-CoV-2 (Mpro) as the receptor, thus paving the way to study the potential application of these hybrids in biomedicine. 相似文献