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91.
Efficient simulations of quantum evolutions of spin-1/2 systems are relevant for ensemble quantum computation as well as in typical NMR experiments. We propose an efficient method to calculate the dynamics of an observable provided that the initial excitation is "local." It resorts to a single entangled pure initial state built as a superposition, with random phases, of the pure elements that compose the mixture. This ensures self-averaging of any observable, drastically reducing the calculation time. The procedure is tested for two representative systems: a spin star (cluster with random long range interactions) and a spin ladder. 相似文献
92.
Braulio Aranda Sergio A. Moya Andres Vega Gonzalo Valdebenito Sofia Ramirez‐Lopez Pedro Aguirre 《应用有机金属化学》2019,33(4)
Aminocarbonylation of aryl halides, homogeneously catalysed by palladium, is an efficient method that can be employed for obtaining amides for pharmaceutical and synthetic applications. In this work, palladium (II) complexes containing P^N ligands were studied as catalysts in the aminocarbonylation of iodobenzene in the presence of diethylamine. Two types of systems were used: a palladium (II) complex formed in situ; and one prepared prior to the catalytic reaction. In general, the palladium complexes studied achieved high conversions in an average reaction time of less than 2 hr, which is less than that for the standard system (Pd (II)/PPh3) used. The pre‐synthesized complexes were faster than their in situ counterparts, as the latter require an induction time to form the Pd/P^N species. The structure and electronic properties of the ligand P^N can influence both the activity and the selectivity of the reaction, stabilizing the acyl‐palladium intermediates formed in a better manner. 相似文献
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Gonzalo Cerruela García Nicolás García-Pedrajas 《Journal of computer-aided molecular design》2018,32(11):1273-1294
Feature selection is commonly used as a preprocessing step to machine learning for improving learning performance, lowering computational complexity and facilitating model interpretation. This paper proposes the application of boosting feature selection to improve the classification performance of standard feature selection algorithms evaluated for the prediction of P-gp inhibitors and substrates. Two well-known classification algorithms, decision trees and support vector machines, were used to classify the chemical compounds. The experimental results showed better performance for boosting feature selection with respect to the standard feature selection algorithms while maintaining the capability for feature reduction. 相似文献
95.
Glasses of the systems Bi2O3-SiO2, Bi2O3-PbO-Ga2O3, Bi2O3-PbO-Ga2O3-GeO2 and Bi2O3-GeO2-Li2O have been prepared and the interaction of their melts with crucibles of different materials has been analytically determined. Silica and porcelain crucibles were very strongly corroded and the glass composition was noticeably altered. Instead platinum crucibles are not affected if the Bi2O3 content is not too high. The color of the glasses changes in all cases from pale yellow to deep brown when the melting temperature reaches approximately 1000 °C. The higher the temperature and the Bi2O3 content the darker the brown color, independently of the nature of the employed crucible. The addition of oxidizing ions (Sb5+, As5+ or Ce4+) to the glass batch prevents darkening. Nanoparticles of elementary bismuth Bi0 are observed by transmission electron microscopy in the glasses melted above 1000 °C. The partial thermoreduction of the Bi2O3 during the heating of the glass melt is proposed as the mechanism responsible for the observed darkening. 相似文献
96.
Jorge Labella Dr. Gonzalo Durán-Sampedro Swathi Krishna Prof. M. Victoria Martínez-Díaz Prof. Dirk M. Guldi Prof. Tomás Torres 《Angewandte Chemie (International ed. in English)》2023,62(5):e202214543
Large π-conjugated systems are key in the area of molecular materials. Herein, we prepare via AuI-catalyzed cyclization a series of fully π-conjugated anthracene-fused oligo-BODIPYs. Their structural and optoelectronic properties were studied by several techniques, ranging from X-ray, UV/Vis, and cyclic voltammetry to transient absorption spectroscopy. As a complement, their electronic structures were explored by means of Density Functional Theory (DFT) calculations. Depending on the size and shape of the π-conjugated skeleton, unique features—such as face-to-face supramolecular organization, NIR absorption and fluorescence as well as strong electron accepting character—were noted. All in all, the aforementioned features render them valuable for technological applications. 相似文献
97.
Dr. Yanira Méndez Dr. Aldrin V. Vasco Galway Ivey Ana Laura Dias Dr. Peter Gierth Bárbara B. Sousa Dr. Claudio D. Navo Angel Torres-Mozas Dr. Tiago Rodrigues Dr. Gonzalo Jiménez-Osés Prof. Gonçalo J. L. Bernardes 《Angewandte Chemie (International ed. in English)》2023,62(44):e202311186
Multicomponent reactions are of utmost importance at generating a unique, wide, and complex chemical space. Herein we describe a novel multicomponent approach based on the combination of the isonitrile-tetrazine (4+1) cycloaddition and the Ugi four-component reaction to generate pyrazole amide derivatives. The scope of the reaction as well as mechanistic insights governing the 4H-pyrazol-4-imine tautomerization are provided. This multicomponent process provides access to a new chemical space of pyrazole amide derivatives and offers a tool for peptide modification and stapling. 相似文献
98.
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100.
Gonzalo Alduncin 《Mathematical Methods in the Applied Sciences》2016,39(18):5242-5257
Macro‐hybrid mixed variational models of two‐phase flow, through fractured porous media, are analyzed at the mesoscopic and macroscopic levels. The mesoscopic models are treated in terms of nonoverlapping domain decompositions, in such a manner that the porous rock matrix system and the fracture network interact across rock–rock, rock–fracture, and fracture–fracture interfaces, with flux transmission conditions dualized. Alternatively, the models are scaled to a macroscopic level via an asymptotic process, where the width of the fractures tends to zero, and the fracture network turns out to be an interface system of one less spatial dimension, with variable high permeability. The two‐phase flow is characterized by a fractional flow dual mixed variational model. Augmented two‐field and three‐field variational reformulations are presented for regularization, internal approximations, and macro‐hybrid mixed finite element implementation. Also abstract proximal‐point penalty‐duality algorithms are derived and analyzed for parallel computing. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献