ZnO nanorods for efficient third harmonic UV generation.

ZnO nanorods grown by both high temperature vapour phase transport and low temperature chemical bath deposition are very promising sources for UV third harmonic generation. Material grown by both methods show comparable efficiencies, in both cases an order of magnitude higher than surface third harmonic generation at the quartz-air interface of a bare quartz substrate. This result is in stark contrast to the linear optical properties of ZnO nanorods grown by these two methods, which show vastly different PL efficiencies. The third harmonic generated signal is analysed using intensity dependent measurements and interferometric frequency resolved optical gating, allowing extraction of the laser pulse parameters. The comparable levels of efficiency of ZnO grown by these very different methods as sources for third harmonic UV generation provides a broad suite of possible growth methods to suit various substrates, coverage and scalability requirements. Potential application areas range from interferometric frequency resolved optical gating characterization of few cycle fs pulses to single cell UV irradiation for biophysical studies.

Photocontrolled DNA Binding of a Receptor-Targeted Organometallic Ruthenium(II) Complex

A photoactivated ruthenium(II) arene complex has been conjugated to two receptor-binding peptides, a dicarba analogue of octreotide and the Arg-Gly-Asp (RGD) tripeptide. These peptides can act as"tumor-targeting devices" since their receptors are overexpressed on the membranes of tumor cells. Both ruthenium-peptide conjugates are stable in aqueous solution in the dark, but upon irradiation with visible light, the pyridyl-derivatized peptides were selectively photodissociated from the ruthenium complex, as inferred by UV-vis and NMR spectroscopy. Importantly, the reactive aqua species generated from the conjugates, [(η6-p-cym)Ru(bpm)(H2O)]2+, reacted with the model DNA nucleobase 9-ethylguanine as well as with guanines of two DNA sequences, 5′dCATGGCT and 5′dAGCCATG. Interestingly, when irradiation was performed in the presence of the oligonucleotides, a new ruthenium adduct involving both guanines was formed as a consequence of the photodriven loss of p-cymene from the two monofunctional adducts. The release of the arene ligand and the formation of a ruthenated product with a multidentate binding mode might have important implications for the biological activity of such photoactivated ruthenium(II) arene complexes. Finally, photoreactions with the peptide-oligonucleotide hybrid, Phac-His-Gly-Met-linker-p5′dCATGGCT, also led to arene release and to guanine adducts, including a GG chelate. The lack of interaction with the peptide fragment confirms the preference of such organometallic ruthenium(II) complexes for guanine over other potential biological ligands, such as histidine or methionine amino acids.

Làsers d"upconversion: llum làser visible a partir de llum infraroja.

Els làsers aporten solucions a una gran varietat de problemes de la vida diària ...

Determination and characterization of quinolones in foodstuffs of animal origin by CE-UV, LC-UV, LC-Fl, LC-MS and LC-MS/MS

In this work methods for the multiresidue determination of the series of quinolones include in the European regulation in food of animal origin are de veloped and validated in line with Commission Decision 2002/657/EC in terms of linearity, decision limit, capability detection, precision and stability. Mult iresidue methods were established to allow the determination of quinolones covered by EU legislation in 2377/90/EC in muscle of chicken, turkey, pig and cow, plasma of cow and pig, liver of pig and milk of cow. First an extraction step was optimized and a SPE step was applied to clean!up and preconcentrate quinolones prior to their separation by CE or LC and determination by CE!UV, LC!UV, LC!Fl, LC!MS with different ion sources (ESI ,ApCI) and different mass analyser (Q, ToF) and LC!E SI!QqQ tandem mass spectrometry. The limits of quantification obtained are always lower than Maxim um Residue Limit (MRL) established by EU for quinolones in animal products and they can be applied to the control of quinolones in foodstuffs of animal origin . Finally the proposed methods were applied to determine quinolones in samples of turkey and pig muscle, pig plasma and milk of cow. Excellent quality parameters and reduced time of analysis were obtained when LC!ESI!MS/MS is used, although the others techniques presented too satisfactory results.

Haciendo visible lo invisible : Peralada, un estudio de caso

Las diferencias entre municipios rurales y urbanos definen escenarios diferentes donde las personas mayores se enfrentan a necesidades también diferentes. En general, la falta de estudios sobre el envejecimiento entendido como un reto y que, además, asuman la variabilidad del proceso, pone al descubierto la necesidad particular de investigaciones que busquen comprender cómo viven los mayores en entornos como el rural. Este artículo describe nuestra experiencia investigadora en un municipio de la Comarca del Alt Empordà, Cataluña, España. El objetivo principal era entender a las personas mayores establecidas en entornos rurales a través de las situaciones de su vida cotidiana, identificar sus necesidades, contribuir a su autonomía funcional y elaborar propuestas de intervención. La muestra la formaron las 223 personas mayores residentes en el municipio de Peralada y Vilanova de la Muga. Los datos se recogieron utilizando los cuestionarios de Barber, Pfeifer y Barthel, y se realizaron entrevistas en profundidad. Los resultados proporcionan cinco claves relevantes al plantear intervenciones en el contexto rural. Básicamente, la intervención profesional en este ámbito debe ir orientada a mantener y fortalecer las redes de apoyo naturales funcionales en el territorio

Influence of EfOM on the oxidation of micropollutants by Ozone and UV/H2O2 in secondary effluents

The aim of this work was to study the influence of effluent organic matter (EfOM) on micropollutants removal by ozone and UV/H2O2. To perform the experiments, deionized water and municipal secondary effluents (SE) were artificially contaminated with atrazine (ATZ) and treated by the two proposed methods. ATZ concentration, COD and TOC were recorded along the reaction time and used to evaluate EfOM effect on the system efficiency. Results demonstrate that the presence of EfOM can significantly reduce the micropollutant removal rate due to competition of EfOM components to react with radicals and/or molecular ozone. The hydroxyl radical scavenging caused by EfOM was quantified as well as the contribution of molecular ozone and �OH radicals during the ozonation of SE. EfOM components promoted higher inhibition of ATZ oxidation by hydroxyl radicals than by molecular ozone.

Fotoluminiscencia visible debida a capas de SiO2. implantadas con silicio y carbono

Se ha n realizado implantaciones de silicio y de carbono + silicio en matrices aislantes de SÍO2 térmico, las cuales, después de un recocido a alta temperatura precipitan en forma de nanocristales de tamaños comprendidos entre 30 y 60 Á. Estas estructuras presentan una intensa fotoluminiscencia en el rojo profundo (1.4-1.6 eV) y el verde (2.0-2.2 eV). La energía e intensidad de las bandas depende fuertemente de la temperatura y duración del recocido. Diferentes comportamientos se han encontrado para las bandas roja y verde, incluyendo la cinética de desexcitación y el origen estructural. Los experimentos de absorción infrarroja, Raman y microscopía electrónica demuestran que los nanocristales son los responsables de la banda roja mientras que agregados amorfos de carbono son los responsables de la verde.

Optical and microstructural properties of MgF2 UV coatings grown by ion beam sputtering process

The optical, mechanical, and microstructural properties of MgF2 single layers grown by ion beam sputtering have been investigated by spectrophotometric measurements, film stress characterization, x-ray photoelectron spectroscopy (XPS), x-ray diffraction, and transmission electron microscopy. The deposition conditions, using fluorine reactive gas or not, have been found to greatly influence the optical absorption and the stress of the films as well as their microstructure. The layers grown with fluorine compensation exhibit a regular columnar microstructure and an UV-optical absorption which can be very low, either as deposited or after thermal annealings at very low temperatures. On the contrary, layers grown without fluorine compensation exhibit a less regular microstructure and a high ultraviolet absorption which is particularly hard to cure. On the basis of calculations, it is shown that F centers are responsible for this absorption, whereas all the films were found to be stoichiometric, in the limit of the XPS sensitivity. On the basis of external data taken from literature, our experimental curves are analyzed, so we propose possible diffusion mechanisms which could explain the behaviors of the coatings.

El repte de la llengua al ciberespai. Ressenya de Josep Gifreu: El català a l'espai de comunicació, Barcelona-Castelló-València. UAB, UJ1, UV, 272 p.

Avui en dia són diverses les llengües que lluiten per colonitzar la cibersocietat a la xarxa , i el català s'hi està forjant un paper gens menyspreable. Josep Gifreu repassa, en una investigació a cavall entre l'assaig històric cultural i la crònica política, l'evolució del procés general de normalització lingüística alhora que descriu el canvi en l'ecosistema mediàtic durant el període 1976-2013: des de la publicació del diari Avui fins a la Galàxia Internet , la revolució radical que , en el nostre cas, ha implicat la incorporació de la versió catalana a Google, l'aparició del domini .cat, la publicació del diari Ara , els més de 400.000 articles de la Viquipèdia o, per contra, el tancament de RTVV.