338 research outputs found

    Evolution of quantum observables: from non-commutativity to commutativity

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    A fundamental aspect of the quantum-to-classical limit is the transition from a non- commutative algebra of observables to commutative one.However, this transition is not possible if we only consider unitary evolutions. One way to describe this transition is to consider the Gamow vectors, which introduce exponential decays in the evolution. In this paper, we give two mathematical models in which this transition happens in the infinite time limit. In the first one, we consider operators acting on the space of the Gamow vectors, which represent quantum resonances. In the second one, we use an algebraic formalism from scattering theory. We construct a non-commuting algebra which commutes in the infinite time limit.MINECO Grant MTM2014- 57129-C2-1-P. Junta de Castilla y Leon Grants BU229P18, VA137G18

    Cooperative Games and Coalition Cohesion Indices: The Choquet–Owen Value

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    In a cooperative game with transferable utility, it is usually assumed that all coalitions are equally feasible. However, if we deal with cooperative games with coalition configuration, only some coalitions are a priori feasible, due to the preferences of the agents. In this paper, we propose a generalization of games with coalition configuration. In our model, the feasibility of a coalition is determined by the cohesion of its members, and obviously, this cohesion does not have to be equal for all coalitions. The cohesion of each coalition will be determined by a cohesion index. We introduce the class of games with cohesion index and propose an allocation rule, which is characterized by using reasonable properties. The cohesion idea is not only a concept related to social groups. In software design, this concept explains the relationships among all the elements of a module. Our value can be applied in this way as we show in the paper

    application in C-H activation catalysis

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    This work was supported by the Spanish Government, the Spanish National Research Council (CSIC). We also thank Dr Martinez from Novozymes. Publisher Copyright: © 2023 RSC.The effect of the temperature in the synthesis of Pd nanoparticles in the metal-enzyme biohybrids is evaluated. The effect on the formation, size, and morphology of nanoparticles was evaluated using C. antarctica B lipase as the protein scaffold. XRD analyses confirmed the formation of crystalline Pd(0) as the metal species in all cases. TEM analyses revealed spherical crystalline nanoparticles with average diameter size from 2 nm at 4 °C synthesis to 10 nm obtained at 50 °C synthesis. The thermal phenomenon was also critical in the final hybrid formation using more complex enzymes, where the relation of the protein structure and temperature and the influence of the latter has been demonstrated to be critical in the reducing efficiency of the enzyme in the final Pd nanoparticle formation, in the metal species, or even in the final size of the nanoparticles. Different Pd biohybrids were evaluated as catalysts in the C-H activation of protected l-tryptophan under mild conditions. Pd@CALB4 showed the best results, with >99% conversion for C-2 arylation in methanol at room temperature with a TOF value of 64 min−1, being 2 or 4 times higher than that of the other synthesized hybrids. This catalyst showed a very high stability and recyclability, maintaining >95% activity after three cycles of use.publishersversionpublishe

    Influence of some oenological practices on the aromatic and sensorial characteristics of white Verdejo wines

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    Changes in the aromatic composition as well as sensory characteristics in Verdejo white wines were analysed based on two factors: the winemaking methodology and the storing time of wine in bottles. The volatile components were determined by GLC-MS, and the sensory profile was designed and assessed according to the ISO 11035 standard. The results showed that when wines were made in oak barrels, either completely or partially, which means the wines were in contact with the lees, the levels of 1-octanol, ethyl heptanoate and ethyl decanoate were significantly affected (P menor que 0.05); the softness sensation was also influenced (P menor que 0.05). However, the amount of time the wines were stored in bottles significantly affected (P menor que 0.05) the levels of 1-hexanol, ethyl heptanoate, ethyl octanoate, ethyl decanoate, hexyl acetate, isoamyl acetate and isoamyl lactate and also an odour note (tropical fruit). The compounds with higher OAV values belong to the groups of esters and fatty acids. For these reasons, the composition and the quality of the aroma of Verdejo white wines appear to be significantly affected both by use of oak barrels in winemaking and the time the wines are stored in bottles

    Influencia de cinco técnicas enológicas en parámetros relacionados con la acidez y el color en vinos tintos de Mencía

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    Se ha estudiado la influencia de cinco técnicas (metodología de elaboración, tipo de recipiente de conservación y tiempo de conservación del vino en rama, temperatura de conservación y tiempo de conservación del vino embotellado) sobre parámetros fisico-químicos y descriptores sensoriales ligados a la acidez y al color en vinos tintos jóvenes de la variedad Mencía en la DO. Valdeorras (Ourense, Galicia). Los resultados muestran que los 19 parámetros estudiados son muy sensibles a las técnicas estudiadas. Tres de las cinco técnicas afectan (p<0,05) a los 19 parámetros y las otras dos (p<0,05) a diez de ellos. La maceración prefermentativa en frio y la conservación del vino en barrica aumentaron la acidez, pero la elaboración tradicional, la conservación del vino en depósito, la conservación del vino en botella durante tres meses y el empleo de una temperatura de conservación del vino embotellado baja y constante fueron más adecuadas para el color. Esto hace necesario establecer condiciones muy concretas para cada técnica según el parámetro considerado

    On-board quality preservation of megrim (Lepidorhombus whiffiagonis) by a novel ozonised-slurry ice system

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    6 páginas, 3 tablas.-- The final publication is available at www.springerlink.comThe use of a combined ozonised-slurry ice system was investigated as a new refrigeration system for the on-board storage of megrim (Lepidorhombus whiffiagonis), a fish species that is usually stored aboard fishing vessels for 1 to 2 weeks. The time elapsed between the catch and unloading at the harbour affects its quality and commercial value directly. Microbiological, chemical and sensory analyses were carried out in megrim after 2 weeks of onboard storage in ozonised slurry ice, slurry ice or flake ice, and for an additional period of 6 days. Sensory analyses revealed that megrim specimens stored in ozonised slurry ice (oSI600 batch) maintained A quality even after 20 days of storage, while counterpart batches stored in flake ice showed B quality at unloading, after 14 days of on-board storage. Storage in ozonised slurry ice (oSI600 batch) also led to significantly (p<0.05) lower counts of aerobic mesophiles, psychrotrophic bacteria, Enterobacteriaceae and proteolytic microorganisms in megrim muscle as compared with flake ice. Biochemical analyses revealed that the use of ozonised-slurry ice or slurry ice alone slowed down the formation of total volatile base-nitrogen (TVBN) and trimethylamine-nitrogen (TMA-N) in comparison with storage in flake ice, also allowing a better control of pH. Lipid hydrolysis and oxidation events also occurred at a lower rate in the ozonised-slurry ice and slurry ice batches than in the flake ice batch. The present study demonstrates that the combination of slurry ice and ozone for the on-board storage of megrim is advisable, thus improving the quality and extending the shelf life of this fish species.This work was supported through a project grant by the Secretar´ıa Xeral de I+D from the Xunta de Galicia (Project PGIDIT04TAL015E).Peer reviewe

    Effect of five enological practices and of the general phenolic composition on fermentation-related aroma compounds in Mencia young red wines

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    The effects of five technological procedures and of the contents of total anthocyanins and condensed tan- nins on 19 fermentation-related aroma compounds of young red Mencia wines were studied. Multifactor ANOVA revealed that levels of those volatiles changed significantly over the length of storage in bottles and, to a lesser extent, due to other technological factors considered; total anthocyanins and condensed tannins also changed significantly as a result of the five practices assayed. Five aroma compounds pos- sessed an odour activity value >1 in all wines, and another four in some wines. Linear correlation among volatile compounds and general phenolic composition revealed that total anthocyanins were highly related to 14 different aroma compounds. Multifactor ANOVA, considering the content of total anthocy- anins as a sixth random factor, revealed that this parameter affected significantly the contents of ethyl lactate, ethyl isovalerate, 1-pentanol and ethyl octanoate. Thus, the aroma of young red Mencia wines may be affected by levels of total anthocyanin

    Data on recovery of 21 amino acids, 9 biogenic amines and ammonium ions after spiking four different beers with five concentrations of these analytes

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    A novel chromatographic method for the simultaneous analysis of nine biogenic amines, 21 amino acids and ammonium ions in beer has been recently described in “A UHPLC method for the simultaneous analysis of biogenic amines, amino acids and ammonium ions in beer” (Redruello et al., 2017) [1]. The present article provides recovery data of the 31 analytes after spiking four different beers with five concentrations of each analyte (15, 30, 60, 120 and 240 µM).This work was performed with the financial support of the Spanish Ministry of Economy and Competitiveness (AGL2013-45431-R) and the Plan for Science, Technology and Innovation 2013–2017 of the Principality of Asturias, which is co-funded by the European Regional Development Fund (GRUPIN14-137).Peer reviewe

    Exploring Thermomyces lanuginosus Lipase (TLL)-PdNPs Nanohybrid as Suitable Catalyst for One-pot Synthesis of Bis(3-indolyl)phenylmethane

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    This work was supported by the Spanish Government, the Spanish National Research Council (CSIC). project PTDC/QUI‐QOR/0712/2020. We also thank Dr. Martinez from Novozymes. We acknowledge support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI) Publisher Copyright: © 2023 The Authors. ChemCatChem published by Wiley-VCH GmbH.Palladium nanohybrids were synthesized and applied to the one-pot synthesis of bis(3-indolyl)methanes by selective C−C bond reaction from benzyl alcohol and indole. A T. lanuginosus lipase-palladium nanoparticles hybrid (Pd@TLL) was synthesized, yielding PdNPs with an average diameter size of 5 nm. This heterogeneous catalyst was first tested in the selective oxidation of benzyl alcohol to benzaldehyde in different solvents. Then, the direct formation of bis(3-indolyl)methane, by in situ oxidation and C−C coupling, was successfully evaluated under different conditions, obtaining >99 % conversion at 80 °C in toluene, with a TOF value of 9 min−1 and 89 % in pure water, demonstrating the versatility of these biohybrids.publishersversionpublishe
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