The effect of different solvents on electrospinning of high performance fibers for electrodes in PEM fuel cell application

Analisi dettagliata sull'influenza dei singoli o insieme di solventi sulle prestazioni degli elettrodi. Lo studio ha condotto all'identificazione di parametri chiave per la produzione di fibre ad alte reseopenEmbargo temporaneo per motivi di segretezza e/o di proprietà dei risultati e/o informazioni sensibil

Estudios preliminares del cultivo de tejidos in-vitro de <i>Brachychiton populneus</i> (Schott & Endl.) R. Br.

En este trabajo se logró desarrollar un protocolo para el establecimiento in vitro de braquiquito. Se ajustó un protocolo de desinfección de semillas y se obtuvieron plántulas germinadas in vitro que se utilizaron como fuente de explantes para la fase de multiplicación. Se evaluó el cultivo de diferentes explantes (tallo, cotiledones, hojas, raíces) en medios de cultivo con sales y vitaminas de M & S (Murashige & Skoog,1962) al 50%, suplementados con los siguientes reguladores de crecimiento: IBA (Ácido indol butírico) y BAP (Bencil amino purina) en diferentes concentraciones. Los mejores resultados en la inducción de brotes fueron obtenidos en el tallo con 2/3 brotes promedio por explante en el medio con las sales y vitaminas M&S reducidas al 50% de su concentración y con reguladores de crecimiento.Facultad de Ciencias Agrarias y Forestale

Application of close-range aerial infrared thermography to detect landfill gas emissions: a case study

Monitoring waste disposal sites is important to check that the produced biogas, potentially explosive, is properly collected by the biogas extraction system of the landfill site and to evaluate the residual biogas flow escaping from upper surface of the landfill. As the biogas migrates to the surface, the soil through which it flows is expected to reach a higher temperature than the surrounding environment; thus, measuring the thermal footprint of the landfill soil surface could allow the detection of biogas leakages and spots suitable for the gas extraction. Close-range aerial infrared thermography is an innovative approach able to identify thermal anomalies with a good resolution over a large region of the landfill surface. A simple procedure to deduce the biogas flow rate emerging from the soil into the atmosphere, based on infrared thermography measurements, is presented. The approach has been applied to a case study concerning a large landfill located in Genoa (Italy). Aerial infrared photographs taken during different days and seasons showed the presence of thermal anomalies over regions along the peripheral boundary of the landfill still not interested in biogas extraction

Functional properties of a newly cloned fish ortholog of the neutral amino acid transporter B0AT1 (SLC6A19)

The functional properties of an ortholog of the B0AT1 (SLC6A19) amino acid transporter, cloned from the intestine of the sea bass Dicentrachus labrax, were investigated. The two-electrode voltage-clamp technique was applied to Xenopus laevis oocytes heterologously expressing the transporter in order to measure the currents associated with the transport process in different conditions. In particular the substrate specificity, the ionic requirements, and possible effects of pH were examined. Among the organic substrates, leucine, glycine, serine and valine generated the largest transport currents with apparent affinities in the lower millimolar range. The importance of Na+ as the driver ion in the transport process is confirmed, although Li+ is also capable to sustain transport, while K+ is not. No evidence of a relevant role of Cl- in the transport activity was found. Concerning the other two kinds of currents commonly found in electrogenic transporters, very fast presteady-state currents were detected in the absence of organic substrate, while lithium-specific leak currents were not observed. The comparison of these properties with those of the mammalian and insect orthologs may give interesting indication for future structure-function studies in this transporter subfamily

Diagnóstico y acciones para mejorar las habilidades escritas y la exposición de conocimientos en Administración I

El presente relato contiene la descripción de la estrategia implementada durante el corriente año en la Comisión 3 de la materia Administración I de la Cátedra A, de la Facultad de Ciencias Económicas de la Universidad Nacional de La Plata, cuya titular, Prof. Lic. Norma A. Paolini, propició la experiencia. La intervención realizada se originó en un Trabajo Final presentado en la Especialización en Docencia Universitaria de la UNLP, motivada en la problemática observada: el bajo porcentaje de alumnos que aprueban la cursada de Administración I. La materia Administración I es de carácter propedéutico, por lo tanto es introductoria a la disciplina. Forma parte de las trece materias correspondientes al Ciclo Básico de la Facultad de Ciencias Económicas, diseñado para ser cursado en los dos primeros años. El Ciclo Básico es el primer tramo de las carreras de Contador Público, Licenciado en Administración y Licenciado en Economía, en el que los alumnos de estas tres carreras deben cursar las mismas materias, para luego poder cursar aquellas específicas de cada carrera. El problema enunciado en el segundo párrafo se refiere a la cantidad de alumnos que cada año aprueba la cursada de la materia Administración I, en la Comisión 3.Eje 5: Problemas y alternativas en los procesos de evaluación de los aprendizajes y la acreditación de saberes. Reflexiones, innovaciones y experiencias de evaluación en la enseñanza universitaria.Secretaría de Asuntos Académico

Acciones para mejorar las habilidades de lectocomprensión de los alumnos de Administración I – Cátedra A de la Facultad de Ciencias Económicas de la Universidad Nacional de La Plata

En la primera parte del trabajo se definirá la capacidad lectora y el rendimiento académico, para luego analizar de forma descriptiva la relación entre ambos conceptos específicamente para los alumnos que ingresan a la Universidad. De esta forma, luego de enmarcar la problemática de referencia, se realizará una propuesta de intervención, que se planteará orientada a la pregunta: ¿qué acciones pueden realizar los docentes de Administración I para mejorar la lectocomprensión de sus alumnos (ingresantes en la materia Administración I – Cátedra A)? El trabajo buscará desarrollar una propuesta de intervención para los alumnos de primer año de la materia Administración I – Cátedra A de la Facultad de Ciencias Económicas de la Universidad Nacional de La Plata. El problema que se abordará en el trabajo se basa en la hipótesis de que las dificultades de lectocomprensión que poseen los alumnos al ingresar a la Facultad obstaculizan el aprendizaje de la materia Administración I.Facultad de Ciencias Económica

Lixo, resíduos sólidos e reciclagem: uma análise comparativa de recursos didáticos

Este trabalho faz uma análise comparativa do tema dos resíduos sólidos em recursos didáticos impressos (livros didáticos, livros paradidáticos e artigos de revista) dirigidos ou assimiláveis pela faixa etária das séries iniciais do ensino fundamental. O destaque da análise é dado à natureza dos conhecimentos sobre resíduos sólidos e lixo veiculados nos textos. Discute-se a problematização da quantidade de lixo, o conceito e tempos de degradação dos materiais, a reciclagem, proposta como solução preferencial para a questão, e algumas inadequações e ausências encontradas nos recursos didáticos. Constataram-se problemas quanto à natureza dos conhecimentos veiculados ou ausentes nos três tipos de recursos didáticos examinados. Esta análise pode contribuir para uma perspectiva mais crítica de educadores envolvidos com a temática ambiental e em particular com o tema dos resíduos sólidos. Garbage, solid waste and recycling: a comparative analysis of teaching resources Abstract This article makes a comparative analysis of the subject of solid waste in printed didactic resources (textbooks, childrens books and magazine articles) addressed to or possible of being understood by students of Elementary school. The focus of the analysis is given to the nature of the knowledge about solid waste present in the texts. We discuss the problem of amount of garbage, recycling proposed as the main solution to this problem, the concept of decaying of materials and some mistakes and absences found in the texts. We identified problems related to the nature of knowledge or absences in the three types of texts. This analysis may contribute to enhance a more critical perspective for educators involved with environmental education and particularly with the subject of solid waste, when selecting didactic resources or implementing educational programs

DESEMPENHO COMERCIAL DA INDÚSTRIA DE MAQUINAS E IMPLEMENTOS AGRÍCOLAS NO BRASIL

Na abertura comercial dos 1990s, a indústria brasileira de máquinas e implementos agrícolas ampliou suas vantagens comparativas, ao contrário do setor de bens de capital brasileiro. Analisando o padrão e volume de comércio internacional destes bens pelo Brasil, identificamos três elementos principais: "externalidades locais, custo-transporte e diferenciação em qualidade nos produtos". Iniciamos com uma sistematização teórica destas relações. Segue uma análise empírica focando, primeiro, na evolução deste comércio e, posteriormente, em seu padrão e direção. Constata-se: (a) o efeito do custo-transporte no volume e padrão de comércio; (b) a concorrência por qualidade sincronizada à renda dos agricultores; e (c) a existência de externalidades locais pelo viés geográfico desta indústria para os antigos centros agrícolas. Este viés também sugere barreiras à entrada associadas a custos fixos.We analyze Brazil's external trade in agricultural machineries since the openness period (the 1990s), rather distinct from the capital goods sectors, and identify three main sources for the observed comparative advantages and overall trade pattern: "local externalities, transport-cost and differences in product quality". These relationships are worked out by means of stylized theoretical models. In the empirical analysis, we examine the trade adjustment during the openness and, then, the pattern and direction of trade. We find out: (a) a notice able effect of transport-cost upon trade volume, pattern and direction, (a) a vertical-quality competition, matched to farmer's in come, and (c) the existence of local externalities as given by this industry's geographical bias towards the old agricultural centers. This bias also indicates entry barriers linked to fixed costs

The “www” of Xenopus laevis Oocytes: The Why, When, What of Xenopus laevis Oocytes in Membrane Transporters Research

After 50 years, the heterologous expression of proteins in Xenopus laevis oocytes is still essential in many research fields. New approaches and revised protocols, but also classical methods, such as the two-electrode voltage clamp, are applied in studying membrane transporters. New and old methods for investigating the activity and the expression of Solute Carriers (SLC) are reviewed, and the kinds of experiment that are still useful to perform with this kind of cell are reported. Xenopus laevis oocytes at the full-grown stage have a highly efficient biosynthetic apparatus that correctly targets functional proteins at the defined compartment. This small protein factory can produce, fold, and localize almost any kind of wild-type or recombinant protein; some tricks are required to obtain high expression and to verify the functionality. The methodologies examined here are mainly related to research in the field of membrane transporters. This work is certainly not exhaustive; it has been carried out to be helpful to researchers who want to quickly find suggestions and detailed indications when investigating the functionality and expression of the different members of the solute carrier families