Influence of metal organic chemical vapour deposition growth conditions on vibrational and luminescent properties of ZnO nanorods

Producción CientíficaA detailed optical characterization by means of micro Raman and cathodoluminescence spectroscopy of catalyst-free ZnO nanorods grown by atmospheric-metal organic chemical vapour deposition has been carried out. This characterization has allowed correlating the growth conditions, in particular the precursors partial-pressures and growth time, with the optical properties of nanorods. It has been shown that a high Zn supersaturation can favor the incorporation of nonradiative recombination centers, which can tentatively be associated with ZnI-related defects. Characterization of individual nanorods has evidenced that ZnI-related defects have a tendency to accumulate in the tip part of the nanorods, which present dark cathodoluminescence contrast with respect to the nanorods bottom. The effect of a ZnO buffer layer on the properties of the nanorods has been also investigated, showing that the buffer layer improves the luminescence efficiency of the ZnO nanorods, revealing a significant reduction of the concentration of nonradiative recombination centers.Ministerio de Ciencia e Innovación (Projects MAT2007-66129, MAT-2010-20441-C02, MAT-2010-16116, and TEC2011-28076-C02-02)Generalitat Valenciana (Prometeo/2011-035 and ISIC/2012/008, Institute of Nanotechnologies for Clean Energies

Fully porous GaN p-n junction diodes fabricated by chemical vapor deposition

Producción CientíficaModern society is experiencing an ever-increasing demand for energy to power a vast array of electrical and mechanical devices. A significant amount of the energy consumed is used for lighting purposes. For instance, this demand is ~17% of the total energy consumed in the USA in 2011 [1]. Thus, any approach that can reduce energy consumption is important. In this context, the development of light emitting diodes (LEDs) incorporating at least one porous component, with improved light extraction efficiency, is being explored intensively [2]. However, up to now, only partially porous p-n junctions have been analyzed for this purpose.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA166A11-2 and VA293U1

Optical and structural characterisation of epitaxial nanoporous GaN grown by CVD

Producción CientíficaIn this paper we study the optical properties of nanoporous gallium nitride (GaN) epitaxial layers grown by chemical vapour deposition on non-porous GaN substrates, using photoluminescence, cathodoluminescence, and resonant Raman scattering, and correlate them with the structural characteristic of these films. We pay special attention to the analysis of the residual strain of the layers and the influence of the porosity in the light extraction. The nanoporous GaN epitaxial layers are under tensile strain, although the strain is progressively reduced as the deposition time and the thickness of the porous layer increases, becoming nearly strain free for a thickness of 1.7 μm. The analysis of the experimental data point to the existence of vacancy complexes as the main source of the tensile strain.Ministerio de Economía, Industria y Competitividad (Projects No. TEC2014-55948-R and MAT2016-75716-C2-1-R (AEI/FEDER, UE)Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. Projects VA293U13 and VA081U16)Comisión Interministerial de Ciencia y Tecnología (Proyect CICYT MAT2010-20441-C02)Ministerio de Economía, Industria y Competitividad (Projects No.ENE2014-56069-C4-4-R

Residual Strain and Electrical Activity of Defects in Multicrystalline Silicon Solar Cells

Producción CientíficaThe growth process by casting methods of multi-crystalline Si results in a crystalline material with, among other defects, a high density of dislocations and grain boundaries. Impurity incorporation and their gathering around grain boundaries and dislocations seem to be the main factor determining the electrical activity of those defects, which limit the minority carrier lifetime. In this work, we analyze multi-crystalline Si samples by combining etching processes to reveal the defects, Raman spectroscopy for strain measurements, and light beam induced current measurements for the localization of electrically active defects. In particular, we have explored the etching routes capable to reveal the main defects (grain boundaries and dislocation lines), while their electrical activity is studied by the light beam induced current technique. We further analyze the strain levels around these defects by Raman micro-spectroscopy, aiming to obtain a more general picture of the correlation between residual stress and electrical activity of the extended defects. The higher stress levels are observed around intra-grain defects associated with dislocation lines, rather than around the grain boundaries. On the other hand, the intra-grain defects are also observed to give dark light beam induced current contrast associated with a higher electrical activity of these defects as compared to the grain boundariesJunta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. A166A11-2)Ministerio de Ciencia e innovación (IPT-420000-2010- -022 INNPACTO program

Differentiation of bee pollen samples according to their intact-glucosinolate content using canonical discriminant analysis

Producción CientíficaA study is presented of the real possibilities of glucosinolate content and chemometrics (canonical discriminant analysis) to differentiate bee pollen samples from four different apiaries (Fuentelahiguera, Monte, Pistacho, Tío Natalio) located in the same geographical area. Fifteen intact-glucosinolates were quantified by means of ultraperformance liquid chromatography coupled to a quadrupole time-of-flight mass detector in forty-nine bee pollen samples. Glucosinolate residues were detected in most of the samples, and these differed in number and concentration. It was possible to directly differentiate one of the apiaries (Fuentelahiguera) from the other three (Monte, Pistacho y Tío Natalio) by comparing glucosinolate content. These three apiaries were differentiated by means of the first two canonical variables obtained from a canonical discriminant analysis. Following this analysis, more than 88% of the samples could be assigned correctly to the Pistacho and Monte apiaries, and 100% to the Tío Natalio apiary.Este trabajo forma parte de los proyectos de investigación financiados por el Ministerio de Economía y Competitividad e INIA-FEDER (RTA2015-00013-C03-01 y 03)

Fully porous GaN p-n junctions fabricated by Chemical Vapor Deposition: a green technology towards more efficient LEDs

Producción CientíficaPorous GaN based LEDs produced by corrosion etching techniques demonstrated enhanced light extraction efficiency in the past. However, these fabrication techniques require further postgrown processing steps, which increase the price of the final system. In this paper, we review the process followed towards the fabrication of fully porous GaN p-n junctions directly during the growth step, using a sequential chemical vapor deposition (CVD) process to produce the different layers that form the p-n junction.Junta de Castilla y León (programa de apoyo a proyectos de investigación – Ref. VA302U13

Educação, conflito e convivência democrática

Após uma caracterização sucinta da actual condição pós-moderna, serão desenvolvidas algumas questões que, pela sua relevância actual no campo da educação, merecem ser revisitadas de modo crítico, nomeadamente, e num primeiro momento, a escola, o conflito e a convivência. Num segundo momento, apontar-se-ão algumas características da escola que fazem dela uma organização com alguma perversidade, hipocrisia e irracionalidade. O último aspecto a ser tratado irá compreender a escola como organização comunicacional ou organização convivencial, onde os conceitos de disciplina, violência, conflito e convivência assumem um sentido mais profundamente democrático.After a succinct characterization of the current postmodern condition, some questions might be developed, because of its current relevance in the education field, they must to be reviewed in a critical way, namely, and firstly, the school, the conflict and the conviviality. Secondly, this article underlines some school’s characteristics that turns it into an organization with a little perversity, hypocrisy and irrationality. The last aspect to be treated is the understanding of the school as a communicative or convivial organization, in which the concepts of discipline, violence, conflict and conviviality assume a more democratic orientation.Enseguida a una caracterización sucinta de la actual condición pos-moderna, serán desarrolladas algunas cuestiones que, por su relevancia actual en el campo de la educación, merecen ser visitadas de modo crítico, nombradamente, y en primero momento, la escuela, el conflicto y la convivencia. En segundo momento, se apuntarán algunas características de la escuela que la hacen una organización con alguna perversidad, hipocresía e irracionalidad. El último aspecto a ser tratado irá comprender la escuela como organización de comunicación u organización de convivencia, donde los conceptos de disciplina, violencia, conflicto e convivencia asumen un sentido más profundamente democrático.(undefined

Cross-species transmission of retroviruses among domestic and wild felids in human-occupied landscapes in Chile

Human transformation of natural habitats facilitates pathogen transmission between domestic and wild species. The guigna (Leopardus guigna), a small felid found in Chile, has experienced habitat loss and an increased probability of contact with domestic cats. Here, we describe the interspecific transmission of feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) between domestic cats and guignas and assess its correlation with human landscape perturbation. Blood and tissue samples from 102 free-ranging guignas and 262 domestic cats were collected and analyzed by PCR and sequencing. Guigna and domestic cat FeLV and FIV prevalence were very similar. Phylogenetic analysis showed guigna FeLV and FIV sequences are positioned within worldwide domestic cat virus clades with high nucleotide similarity. Guigna FeLV infection was significantly associated with fragmented landscapes with resident domestic cats. There was little evidence of clinical signs of disease in guignas. Our results contribute to the understanding of the implications of landscape perturbation and emerging diseases

Dilemas e desafios da função docente na sociedade atual: os sentidos da mudança

A abordagem propõe a constatação das exigências de mudança na atualidade, decorrentes do quadro complexo em que se dá a educação escolar hoje para pensar os rumos da atuação/formação do professor. Procurou-se analisar as questões presentes nas tensões vividas pelos docentes no processo pedagógico (curricular), analisando os reflexos do pensamento moderno e pós-moderno na trajetória docente. Em função dessa proposta, são apresentados resultados da investigação desenvolvida com alunos(as) da disciplina de Currículos e Programas do Curso de Pedagogia e posteriormente aprofundada em Projeto de Pesquisa (Prolicen-UFPR) no ano de 2001. Os pesquisadores investigaram professores de escolas públicas de Curitiba e região metropolitana. Buscou-se a leitura de significados, necessidades e opções presentes na condução e moldagem das práticas docentes na atualidade, considerando o conceito de habitus de BOURDIEU e as possibilidades de análise abertas por SACRISTÁN, GIROUX e GRAMSCI. Procurou-se desenredar a função docente da profusão de exigências que lhe são postas hoje, numa contribuição ao redirecionamento das propostas prescritivas de mudança e, sobretudo, de formação do professor

Cost-effectiveness analysis of pemetrexed versus docetaxel in the second-line treatment of non-small cell lung cancer in Spain: results for the non-squamous histology population

BackgroundThe objective of this study was to conduct a cost-effectiveness evaluation of pemetrexed compared to docetaxel in the treatment of advanced or metastatic non-small cell lung cancer (NSCLC) for patients with predominantly non-squamous histology in the Spanish healthcare setting.MethodsA Markov model was designed consisting of stable, responsive, progressive disease and death states. Patients could also experience adverse events as long as they received chemotherapy. Clinical inputs were based on an analysis of a phase III clinical trial that identified a statistically significant improvement in overall survival for non-squamous patients treated with pemetrexed compared with docetaxel. Costs were collected from the Spanish healthcare perspective.ResultsOutcomes of the model included total costs, total quality-adjusted life years (QALYs), total life years gained (LYG) and total progression-free survival (PFS). Mean survival was 1.03 years for the pemetrexed arm and 0.89 years in the docetaxel arm; QALYs were 0.52 compared to 0.42. Per-patient lifetime costs were € 34677 and € 32343, respectively. Incremental cost-effectiveness ratios were € 23967 per QALY gained and € 17225 per LYG.ConclusionsPemetrexed as a second-line treatment option for patients with a predominantly non-squamous histology in NSCLC is a cost-effective alternative to docetaxel according to the € 30000/QALY threshold commonly accepted in Spain