Time filter

Source Type

Josa D.,University of Santiago de Compostela | Rodriguez-Otero J.,University of Santiago de Compostela | Cabaleiro-Lago E.M.,Alfonso X El Sabio University | Rellan-Pineiro M.,University of Santiago de Compostela
Chemical Physics Letters | Year: 2013

The performance of a variety of DFT-D functionals with empirical dispersion correction (B97-D, PBE-D, B-LYP-D, BP86-D) and specialized functionals for the treatment the non-covalent interactions (M05-2X, M06-2X) has been evaluated on four representative groups of complexes with π⋯π interactions: (1) dispersion-dominated complexes taken from the S22 database; (2) complexes with eclipsed planar polycyclic aromatic hydrocarbons, PAHs; (3) complexes with curved PAHs; (4) mixed complexes made up by planar and curved PAHs. Our study shows that, in general, calculations employing DFT-D functionals provide more accurate interaction energies than those from M05-2X and M06-2X. © 2012 Elsevier B.V. All rights reserved.

Ochoa-Gomez J.R.,Tecnalia | Ochoa-Gomez J.R.,Alfonso X El Sabio University | Gomez-Jimenez-Aberasturi O.,Tecnalia | Ramirez-Lopez C.,Tecnalia | Maestro-Madurga B.,Tecnalia
Green Chemistry | Year: 2012

The synthesis of glycerol 1,2-carbonate (GC) by transesterification of glycerol with dimethyl carbonate (DMC) using triethylamine (TEA) as a facile separable homogeneous catalyst has been studied at different temperatures, DMC/glycerol molar ratios and TEA/glycerol molar ratios. Reaction rate increases dramatically with temperature and TEA/glycerol molar ratio but the reaction is difficult to stop in the target molecule at the highest TEA/glycerol molar ratios because GC undergoes further transesterification to glycerol dicarbonate (GDC). However, good reaction control can be achieved by working at a TEA/glycerol molar ratio of 0.1: a 99% glycerol conversion and a 98% GC yield are obtained in 2.5 h with a DMC/glycerol molar ratio of 4 at refluxing temperature (88°C → 68°C). At 90°C glycidol is also formed in 6-10% yields. A mechanism to justify its synthesis is proposed. GDC formation can be avoided at conversions below 100% but in this case GC is highly impurified with glycerol after solvent removal by evaporation. To separate both chemicals a liquid-liquid extraction method has been developed. Selective extraction solvents for GC, such as methyl isobutyl ketone (MIBK) or DMC, were found using the method of miscibility numbers. GC is selectively extracted at room temperature in MIBK in a 100% yield with purity higher than 98% from a glycerol-GC mixture consisting of 80 wt% GC by using a MIBK/mixture mass ratio of 1.6 and three extraction steps. © 2012 The Royal Society of Chemistry.

Martin A.,Alfonso X El Sabio University
Revista Espanola de Cardiologia Suplementos | Year: 2013

Atrial fibrillation is the most frequently encountered sustained arrhythmia in emergency departments. In Spain, it is becoming increasingly common. It is a serious condition that often affects elderly individuals who are at a high risk of stroke, who may have structural heart disease and associated comorbid conditions, and who usually present with acute symptoms associated with the arrhythmia. All of these factors have an important influence on treatment decisions. Since episodes of recent-onset atrial fibrillation are usually managed in the emergency department, it is vitally important that these departments implement appropriate treatment that increases the likelihood that sinus rhythm will be restored and that establishes prophylaxis for stroke as early as possible. This article contains a review of the methods of stroke prophylaxis used during the restoration of sinus rhythm, the aim of and strategies used for heart rate control, and the indications for, the factors influencing decisions on and the techniques used for restoring sinus rhythm, with particular emphasis on episodes of recent-onset atrial fibrillation. © 2013 Sociedad Españñola de Cardiologíía.

Garnacho-Castano M.V.,University of Barcelona | Lopez-Lastra S.,Institute Pasteur Paris | Mate-Munoz J.L.,Alfonso X El Sabio University
Journal of Sports Science and Medicine | Year: 2014

The objectives of the study were to determine the validity and reliability of peak velocity (PV), average velocity (AV), peak power (PP) and average power (AP) measurements were made using a linear position transducer. Validity was assessed by comparing measurements simultaneously obtained using the Tendo Weightlifting Analyzer System® and T-Force Dynamic Measurement System® (Ergotech, Murcia, Spain) during two resistance exercises, bench press (BP) and full back squat (BS), performed by 71 trained male subjects. For the reliability study, a further 32 men completed both lifts using the Tendo Weightlifting Analyzer System® in two identical testing sessions one week apart (session 1 vs. session 2). Intraclass correlation coefficients (ICCs) indicating the validity of the Tendo Weightlifting Analyzer System® were high, with values ranging from 0.853 to 0.989. Systematic biases and random errors were low to moderate for almost all variables, being higher in the case of PP (bias ±157.56 W; error ±131.84 W). Proportional biases were identified for almost all variables. Test-retest reliability was strong with ICCs ranging from 0.922 to 0.988. Reliability results also showed minimal systematic biases and random errors, which were only significant for PP (bias -19.19 W; error ±67.57 W). Only PV recorded in the BS showed no significant proportional bias. The Tendo Weightlifting Analyzer System® emerged as a reliable system for measuring movement velocity and estimating power in resistance exercises. The low biases and random errors observed here (mainly AV, AP) make this device a useful tool for monitoring resistance training. © 2014, Journal of Sports Science and Medicine.

Rodriguez A.,Alfonso X El Sabio University | Ortega F.,University of Oviedo | Concepcion R.,University of Oviedo
Expert Systems with Applications | Year: 2013

The acquisition of custom design equipment may be accomplished by selecting a supplier to launch a product development project. That selection is usually performed by a bidding process that requires a procedure for the evaluation of proposals. This paper proposes a modification to a method for multi-criteria decision analysis as a support in evaluation. The method, originally implemented by several authors, is based on a combination of fuzzy Analytic Hierarchy Process (AHP) and the Technique for Order Preference by Similarity to the Ideal Solution (TOPSIS). The proposed modifications permit the direct entry of data to three types of parameters (numerical parameters, binary descriptors and linguistic variables). The calculation of weights for each evaluation criterion is performed by a new approach to fuzzy AHP that facilitates the assessment and permits the simultaneous verification of consistency. The proposed improved method includes a procedure for the detection and analysis of possible problems of rank reversal. A numerical example is presented using data from an actual case of a request for proposals for the supply of customized lottery ticket printers. © 2012 Elsevier Ltd. All rights reserved.

Discover hidden collaborations