Ver para creer : un nuevo enfoque en el aprendizaje de los procesos redox

El objetivo general de «Ver para creer» es presentar una propuesta didáctica sobre las reacciones de transferencia de electrones, a partir de la observación de procesos redox macroscópicos, que conducen a niveles de representación microscópicos y simbólicos. Se incluyen cuatro experiencias: el reloj que funciona con una naranja, precipitación electroquímica de metales disueltos, la corrosión del hierro y estados de oxidación del manganeso. Esta propuesta está dirigida a alumnado de 4º de ESO y Bachillerato. Es un nuevo enfoque que se puede implantar en el aula mediante la presentación de material audiovisual, experiencias de cátedra o como prácticas de laboratorio

Ab initio HF and DFT calculation of the second order NLO response of tetrathiafulvalene and 1,3‐dithiole derivatives

Trabajo presentado a la "International Conference of Computational Methods in Sciences and Engineering (ICCMSE)" celebrada del 25 al 30 de Septiembre en Grecia.-- Publicado en: AIP Conf. Proc. 963, pp. 326-329; doi:http://dx.doi.org/10.1063/1.2836075The nonlinear optical properties of new tetrathiafulvalenes and 1,3-dithioles have been studied using first principle methods. The higher hyperpolarizabilities of the extended 1,3-dithioles compared to Tetrathiafulvalene analogs are explained on the basis of the less localized HOMO of the former giving rise to higher transition dipole moments and a more pronounced decrease of the HOMO-LUMO gap on chain extension.Financial support from MEC-FEDER (CTQ2005-01368) and Gobierno de Aragón-Fondo Social europeo (E-39) is acknowledged.Peer reviewe

Metabolites involved in cellular communication among human cumulus-oocyte-complex and sperm during in vitro fertilization

This article is distributed under the terms of the Creative Commons Attribution 4.0 International License.-- et al.[Background]: Fertilization is a key physiological process for the preservation of the species. Consequently, different mechanisms affecting the sperm and the oocyte have been developed to ensure a successful fertilization. Thus, sperm acrosome reaction is necessary for the egg coat penetration and sperm-oolema fusion. Several molecules are able to induce the sperm acrosome reaction; however, this process should be produced coordinately in time and in the space to allow the success of fertilization between gametes. The goal of this study was to analyze the metabolites secreted by cumulus-oocyte-complex (COC) to find out new components that could contribute to the induction of the human sperm acrosome reaction and other physiological processes at the time of gamete interaction and fertilization. [Methods]: For the metabolomic analysis, eighteen aliquots of medium were used in each group, containing: a) only COC before insemination and after 3 h of incubation; b) COC and capacitated spermatozoa after insemination and incubated for 16–20 hours; c) only capacitated sperm after 16–20 h in culture and d) only fertilization medium as control. Six patients undergoing assisted reproduction whose male partners provided normozoospermic samples were included in the study. Seventy-two COC were inseminated. [Results]: The metabolites identified were monoacylglycerol (MAG), lysophosphatidylcholine (LPC) and phytosphingosine (PHS). Analysis by PCR and in silico of the gene expression strongly suggests that the cumulus cells contribute to the formation of the PHS and LPC. [Conclusions]: LPC and PHS are secreted by cumulus cells during in vitro fertilization and they could be involved in the induction of human acrosome reaction (AR). The identification of new molecules with a paracrine effect on oocytes, cumulus cells and spermatozoa will provide a better understanding of gamete interaction.This study was supported by grant GV/2009/097 from Department of Education, Generalitat Valenciana, Vicerrectorado de Investigación, University of Alicante, Alicante, Spain (Vigrob-137), the Spanish Ministerio de Economía y Competitividad AGL2012-40180-C03-02 and Fundación Seneca (04542/GERM/06).Peer Reviewe

Colorantes orgánicos derivados de la trifenilamina con varios puntos de anclaje para aplicación en celdas solares

Los inconvenientes asociados al empleo de combustibles fósiles para la obtención de energía están impulsando la investigación hacia fuentes renovables. Una de las que más crecimiento ha experimentado es la energía solar, cuyo mercado sigue dominado por paneles de silicio ultrapuro. Recientemente han emergido una variedad de dispositivos solares con perspectivas de viabilidad en un futuro próximo. Un ejemplo de ello son las celdas de tipo Grätzel o DSSCs, en las cuales un colorante transforma la luz solar en electrones, y que presenta ciertas ventajas como su precio o la posibilidad de trabajar bajo condiciones de escasa luminosidad, o incluso de luz artificial. En este Trabajo de Fin de Máster, se han sintetizado colorantes derivados de la trifenilamina, utilizando ácido cianoacético como grupo aceptor y unidos a la plataforma calixareno, empleando como espaciadores diferentes heterociclos para modular sus propiedades. Se han mejorado las propiedades fotovoltaicas, casi se ha alcanzado el 5% de eficiencia, lo que supone un aumento del 28% con respecto al colorante Cx-2-TPA ya publicado

Theoretical understanding of the increment of upon protonation of pyridine peripheral octupolar molecules: Toward nonlinear optical sensors

6 pages, 6 tables, 4 figures.In this article, we present a computational study of the nonlinear optical properties of pyridine-based octupolar molecules in their neutral and fully triprotonated states. The effect of the core substitution and the degree of conjugation with the periphery has been also established and confirms the possibility of fine-tuning the nonlinear optical response. Computations involving the time-dependent density-functional theory approach serve to further explore the existence of excited states with nonzero dipole moment. From these results, the origin of the high second-order nonlinear optical activity upon protonation is addressed.The present work was supported in part by the Dirección General de Enseñanza Superior DGES, MEC, Spain through research Project Nos. CTQ2006-14987-C02-01 and CTQ2005-01368. The authors are also indebted to Junta de Andalucía and Gobierno de Aragón Spain for funding their research groups FQM-0159 and E39. M.C.R.D. is grateful to the MEC/Fulbright for her Postdoctoral Fellowship at the Georgia Institute of Techology. J.C. is grateful to the MEC of Spain for an I3 professorship position of Chemistry at the University of Málaga and M.M.O. acknowledges the MEC for a personal grant.Peer reviewe

Separation, determination and composition profile of lipids in biodiesel using hyphenation of gradient HPTLC with fluorescence detection by intensity changes and mass spectrometry

Trabajo presentado al 250th ACS National Meeting, celebrado en Boston (US) del 16 al 20 de agosto de 2015.Spanish MINECO and FEDER (UE) (Plan Nacional I+D+I, project CTQ2012-035535) and to DGA-ESF. M.P.L. thanks MINECO for grant BES-2013-063673).Peer Reviewe

Terminal Au-N and Au-O Units in Organometallic Frames

Since gold is located well beyond the oxo wall, chemical species with terminal Au−N and Au−O units are extremely rare and limited to low coordination numbers. We report here that these unusual units can be trapped within a suitable organometallic frame. Thus, the terminal auronitrene and auroxyl derivatives [(CF3)3AuN]− and [(CF3)3AuO]− were identified as local minima by calculation. These open-shell, high-energy ions were experimentally detected by tandem mass spectrometry (MS2): They respectively arise by N2 or NO2 dissociation from the corresponding precursor species [(CF3)3Au(N3)]− and [(CF3)3Au(ONO2)]− in the gas phase. Together with the known fluoride derivative [(CF3)3AuF]−, they form an interesting series of isoleptic and alloelectronic complexes of the highly acidic organogold(iii) moiety (CF3)3Au with singly charged anions X− of the most electronegative elements (X=F, O, N). Ligand-field inversion in all these [(CF3)3AuX]− species results in the localization of unpaired electrons at the N and O atoms