Carbon materials as template for the preparation of mixed oxides with controlled morphology

Resumen del libro de actas del Congreso: 5th Czech-Italian-Spanish Conference on Molecular Sieves and Catalysis, celebrado en Segovia del 16 al 19 de junio de 2013Bulk mixed oxide catalysts are widely used for many applications, such as catalysts for selective oxidation processes, electrocatalysts for fuel cells, gas sensors, and solid oxide electrolysers for the production of hydrogen. VPO (vanadium and phosphorous oxides) are one of the bulk mixed oxide materials which are of interest nowadays since they are active catalysts for saturated hydrocarbon activation. With the conventional synthesis procedures for preparing bulk mixed oxides is really difficult to control the morphology and the porous structure of these materials. In practice, there are just a few works about the synthesis of mixed oxide materials with controlled morphology. The aim of this work was to describe new approaches for the preparation of VPO mixed oxides materials with spherical morphology. A carbon material was prepared using cellulose as starting material by hydrothermal treatment with phosphoric acid at 200ºC and carbonized at 500ºC. SEM analysis showed that carbon spheres with diameter up to 0.5 m were prepared by this procedure. These phosphorous containing carbon material was impregnated with the appropriate amount of vanadium oxide species in order to obtain a monolayer of VOx species on the surface of the carbon materials following a procedure described previously (1). By this manner, a carbon supported VOx material with spherical morphology was obtained (VPO/Csph). The calcination of this material was optimized in order to obtain VPO spheres with diameter up to 1-2 m and with BET area values close to 100 m2/g. Figure 1 shows a SEM image of this sample (VPOsph). The presence of vanadium pyrophosphate phase, which has been described as the active phase of this catalytic system, was identified by XRD and Raman spectroscopy. Thus, the chemical composition as well as the morphology and porous structure of these new spherical materials makes them quite promising as catalysts

Monte Carlo analysis of voltage noise in sub-micrometre semiconductor structures under large-signal regime

Sea analiza el método de Monte Carlo y el ruidoUsing an ensemble Monte Carlo technique, we investigate voltage noise(related to diffusion noise sources) in GaAs n+nn+ structures operating underlarge-amplitude periodic signals. A pronounced noise contribution aroundthe frequency of the excitation signal f0 is evidenced. This contribution is mainly associated with the time-varying field sustained by the n region. Its presence and importance depends on the length of the n region and the value of f0. This additional contribution in the voltage noise spectrum tends to disappear for values of f0 beyond the cut-off of the noise related to the n region. On the other hand, the level of low-frequency noise under large-signal conditions is higher than under mall-signal operation due to theincrease of the effective resistance of the structures

Inclusive Curriculum

En el presente artículo se analiza un colegio español en base a los principios educativos propuestos por Juan Manuel Escudero (2006). Tales principios están creados para la mejora de la educación a través de cinco éticas diferentes: justicia, cuidado, crítica, profesionalidad y finalmente la comunidad democrática. Con tales éticas se observa si el centro escogido cumple con una mejora educativa a través del análisis de los diferentes planes y proyectos que desarrolla el centro en su comunidad educativa. Finalmente, se estudia en profundidad uno de los planes para entender la importancia y la repercusión de proyectos con componente emocional.In this article a Spanish school is analysed based on educational principles proposed by Juan Manuel Escudero (2006). Such principles are created to improve education through five different ethics: fairness, caring, critical, professionalism and finally democratic community. With such ethics, it is seen whether the chosen school has an educational improvement through analysis of the various plans and projects developed by the school in its educational community. Finally, there is a deep study of one of the plans to understand the importance and impact of projects with emotional component

Purification of Starch Granules from Arabidopsis Leaves and Determination of Granule-Bound Starch Synthase Activity

Starch constitutes the most important carbon reserve in plants and is composed of branched amylopectin and linear amylose. The latter is synthesized exclusively by the Granule-Bound Starch Synthase (GBSS, EC 2.4.1.21). Here we report a readily reproducible, specific and highly sensitive protocol, which includes the isolation of intact starch granules from Arabidopsis thaliana leaves and the subsequent determination of GBSS activity. We have applied this method to study GBSS activity in diurnal cycles in vegetative growth and during the photoperiodic transition to flowering in Arabidopsis (Tenorio et al., 2003; Ortiz-Marchena et al., 2014).España,MINECO CSD2007-00057, BIO2008-02292, and BIO2011-28847-C02-00España, Junta de Andalucía P06-CVI-01450 and P08-AGR-0358

Activated carbons as catalytic support for Cu nanoparticles

There are a wide range of catalytic applications for Cu-based nanoparticles materials, since Cu is an abundant and inexpensive metal and Cu nanoparticles possess unusual electrical, thermal and optical properties. The possible modification of the chemical and physical properties of these nanoparticles using different synthetic strategies and conditions and/or via postsynthetic chemical treatments has been largely responsible for the rapid growth of interest in these nanomaterials and their applications in catalysis. A previous work have explored the possibilities of SBA-15 (1,2) as support for Cu nanoparticles. In the present contribution, those results will be compared with the use of a carbon material as support, since activated carbon present many advantages with respect SBA, as the high surface area.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Submillimeter-Wave Oscillations in Recessed InGaAs/InAlAs Heterostructures: Origin and Tunability

By means of an ensemble Monte Carlo simulator, the appeareance of THz oscillations in InAlAs/InGaAs slot diodes is predicted when the applied bias exceeds the threshold for intervalley transfer. Such high frequency is attained by the presence of a Gunn-like effect in the recess-to-drain region of the device channel whose dynamics is controlled by ballistic gamma valley electrons. In this work we explain the mechanism at the origin of this effect and also the influence of the bias conditions, delta-doping, recess-to-drain distance and recess length on the frequency of the ultra-fast Gunn like oscillations. The simulations show that a minimum value for the delta-doping is necessary to have enough carrier concentration under the recess and allow the oscillations to emerge. Finally, we show that shortening the devices (small recess and recess-to-drain lengths) increases of the oscillation frequency, so providing an interesting frequency tuneability of this THz source.ROOTHz (FP7-243845

Effect of the solvent on the conformational behavior of the alanine dipeptide deduced from MD simulations

In general, peptides do not exhibit a well-defined conformational profile in solution. However, despite the experimental blurred picture associated with their structure, compelling spectroscopic evidence shows that peptides exhibit local order. The conformational profile of a peptide is the result of a balance between intramolecular interactions between different atoms of the molecule and intermolecular interactions between atoms of the molecule and the solvent. Accordingly, the conformational profile of a peptide will change upon the properties of the solvent it is soaked. To get insight into the balance between intra- and intermolecular interactions on the conformational preferences of the peptide backbone we have studied the conformational profile of the alanine dipeptide in diverse solvents using molecular dynamics as sampling technique. Solvents studied include chloroform, methanol, dimethyl sulfoxide, water and N-methylacetamide. Different treatments of the solvent have been studied in the present work including explicit solvent molecules, a generalized Born model and using the bulk dielectric constant of the solvent. The diverse calculations identify four major conformations with different populations in the diverse solvents: the C7 eq only sampled in chloroform; the C5 or extended conformation; the polyproline (PII) conformation and the right-handed a-helix conformation (aR). The results of present calculations permit to analyze how the balance between intra- and intermolecular interactions explains the populations of the diverse conformations observed.Postprint (published version

Atom Transfer Radical Reactions as a Tool for Olefin Functionalization : On the Way to Practical Applications

Transition-metal-catalyzed atom transfer radical reactions of halogenated compounds with olefins constitute a versatile tool in organic synthesis within the area of C–C bond forming transformations. The inter- or intramolecular versions, atom transfer radical addition (ATRA) or cyclization (ATRC), respectively, lead to the atom-economic, useful synthesis of compounds that can be further functionalized. This contribution summarizes the recent developments in this area in terms of catalyst design as well as the applicability of this methodology in sequential, domino, or tandem reactions.We thank the Ministerio de Ciencia e Innovacion (grants CTQ2008-00042BQU and CTQ2008-06866-CO2-02/BQU), Consolider Ingenio 2010 (CSD2006-0003), and the Junta de Andalucia (Grant P07-FQM-02794) for financial support

Copper-catalysed radical reactions of alkenes, alkynes and cyclopropanes with N–F reagents

The mild generation of nitrogen-centred radicals from N–F reagents has become a convenient synthetic tool. This methodology provides access to the aminative difunctionalisation of alkenes and alkynes and the radical ring-opening of cyclopropanes, among other similar transformations. This review article aims to provide an overview of recent developments of such processes involving radical reactions and N–F reagents using copper-based catalysts.We thank Ministerio de Economía y Competitividad (MINECO) (CTQ2017-82893-C2-1-R) and Universidad de Huelva (PO FEDER 2014-2020 UHU-1254043) for grants

A universal literary canon based on multilingual encyclopedic data: Proposal of a method for the ranking of literary works using quantitative data obtained from Wikidata and Wikipedia

DOI de la versión publicada en castellano: htps://doi.org/10.3989/redc.2023.3.2013The research described in this article aims to verify the use of Wikidata and Wikipedia as a source to identify a universal literary canon. Both Wikimedia Foundation projects are placed in the context of data on literary works. The methodology used is based on the construction of a dataset from specific data on literary works retrieved from Wikidata and Wikipedia editions in all languages. The depth of description of the items of literary works in Wikidata and their pres-ence and level of elaboration of the corresponding articles in Wikipedia are analyzed. The authors use K-means to define three clusters of literary works that allow the identification of a set of works that can be used to create a universal literary canon. Wiki3DRank is proposed as a metric that allows the literary works analyzed to be selected and ranked. The study deals with the analysis of the language of literary works and their presence in Wikipedia, their temporal distribution. The article includes a discussion section with reflections on the results obtained and concludes with the proposal to use Wikidata and Wikipedia as an alternative source for the elaboration of both global and language-specific literary canons