Field-Assisted and Thermionic Contributions to Conductance in SnO2 Thick-Films

A deep analysis of conductance in nanostructured SnO2 thick films has been performed. A model for field-assisted thermionic barrier crossing is being proposed to explain the film conductivity. Themodel has been applied to explain the behavior of resistance in vacuum of two sets of nanostructured thick-films with grains having two well-distinct characteristic radii (R = 25nm and R = 125 nm). In the first case the grain radius is shorter than the depletion region width, a limit at which overlapping of barriers takes place, and in the second case it is longer. The behavior of resistance in the presence of dry air has been explained through the mechanism of barrier modulation through gas chemisorption.Fil: Malagú, C.. Universita Di Ferrara; ItaliaFil: Carotta, M. Cristina. Universita Di Ferrara; ItaliaFil: Martinelli, Giuliano. Universita Di Ferrara; ItaliaFil: Ponce, Miguel Adolfo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Castro, Miriam Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Aldao, Celso Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

(Ti,Sn) solid solution-based gas sensors for new monitoring of hydraulic oil degradation

The proper operation of a fluid power system in terms of efficiency and reliability is directly related to the fluid state; therefore, the monitoring of fluid ageing in real time is fundamental to prevent machine failures. For this aim, an innovative methodology based on fluid vapor analysis through metal oxide (shortened: MOX) gas sensors has been developed. Two apparatuses were designed and realized: (i) a dedicated test bench to fast-age the fluid under controlled conditions; (ii) a laboratory MOX sensor system to test the headspace of the aged fluid samples. To prepare the set of MOX gas sensors suitable to detect the analytes’ concentrations in the fluid headspace, different functional materials were synthesized in the form of nanopowders, characterizing them by electron microscopy and X-ray diffraction. The powders were deposited through screen-printing technology, realizing thick-film gas sensors on which dynamical responses in the presence of the fluid headspace were obtained. It resulted that gas sensors based on solid solution TixSn1–xO2 with x = 0.9 and 0.5 offered the best responses toward the fluid headspace with lower response and recovery times. Furthermore, a decrease in the responses (for all sensors) with fluid ageing was observed

Thick-film gas sensors based on vanadium-titanium oxide powders prepared by sol-gel synthesis

Two titania powders modified by 10 at.% of vanadium were prepared by two different sol-gel routes. The powders fired at 650 °C had the rutile structure. These powders were used to produce prototype thick-film sensors. Four series of thick-film samples were fabricated by screen-printing, fired for 1 h at 650 and 850 °C. The morphology and gas-sensing properties were examined and compared with those of pure and Ta-added titania films, previously studied by the authors. Ta addition inhibited the anatase-to-rutile phase transformation during heating and was also effective in keeping the TiO2 grain size in the nanometre range. On the contrary, V addition facilitated the anatase-to-rutile phase transformation. Thick films obtained from the two powders had similar conductance behaviour vs. temperature. The gas response of the films was affected by both the grain size and firing temperature. © 2003 Elsevier Ltd. All rights reserved

A portable air-quality station based on thick film gas sensors for real time detection of traces of atmospheric pollutants

Different functional materials, single or mixed nano-crystalline semiconductor oxides, were synthesized via appropriated wet-chemistry routes. The powders were used to fabricate metal oxide (MOX) thick film gas sensors. Portable monitoring stations based on the aforementioned sensors were prepared, including electronics for acquisition, processing and wireless transmission of the data. Results of long term trials in field, carried out locating few units closely to as many conventional fixed-site monitoring stations, have been reported. The comparison was performed between the temporal evolution of the conductivity changes of the sensors with the pollutants' concentrations, as measured by the analytical instruments

nanograined anatase titania based optochemical gas detection

Optochemical sensing properties of thick films of titanium dioxide (titania) in anatase phase have been studied and compared with tin dioxide cassiterite. Anatase titania exhibits a large photoluminescence response to nitrogen dioxide, which acts as a luminescence enhancer. Intrinsic surface phenomena rather than bulk defectivity are proposed to account for the behaviour and the experimental results are fitted with the Langmuir model. Good operational performances working at room temperature are achieved

Establishment of Mouse Embryonic Stem Cell-Derived Erythroid Progenitor Cell Lines Able to Produce Functional Red Blood Cells

BACKGROUND: The supply of transfusable red blood cells (RBCs) is not sufficient in many countries. If erythroid cell lines able to produce transfusable RBCs in vitro were established, they would be valuable resources. However, such cell lines have not been established. To evaluate the feasibility of establishing useful erythroid cell lines, we attempted to establish such cell lines from mouse embryonic stem (ES) cells. METHODOLOGY/PRINCIPAL FINDINGS: We developed a robust method to obtain differentiated cell lines following the induction of hematopoietic differentiation of mouse ES cells and established five independent hematopoietic cell lines using the method. Three of these lines exhibited characteristics of erythroid cells. Although their precise characteristics varied, each of these lines could differentiate in vitro into more mature erythroid cells, including enucleated RBCs. Following transplantation of these erythroid cells into mice suffering from acute anemia, the cells proliferated transiently, subsequently differentiated into functional RBCs, and significantly ameliorated the acute anemia. In addition, we did not observe formation of any tumors following transplantation of these cells. CONCLUSION/SIGNIFICANCE: To the best of our knowledge, this is the first report to show the feasibility of establishing erythroid cell lines able to produce mature RBCs. Considering the number of human ES cell lines that have been established so far, the intensive testing of a number of these lines for erythroid potential may allow the establishment of human erythroid cell lines similar to the mouse erythroid cell lines described here. In addition, our results strongly suggest the possibility of establishing useful cell lines committed to specific lineages other than hematopoietic progenitors from human ES cells

The Prolyl Isomerase Pin1 Modulates Development of CD8+ cDC in Mice

We have identified a novel role for Pin1 as a modulator of CD8+ cDC development. Consistent with reduced numbers of CD8+ cDC in Pin1-null mice, we find that the absence of Pin1 impairs CD8+ T cell proliferation in response to infection with Listeria monocytogenes. These data suggest that, via regulation of CD8+ cDC production, Pin1 may serve as an important modulator of adaptive immunity

Silencing and Nuclear Repositioning of the λ5 Gene Locus at the Pre-B Cell Stage Requires Aiolos and OBF-1

The chromatin regulator Aiolos and the transcriptional coactivator OBF-1 have been implicated in regulating aspects of B cell maturation and activation. Mice lacking either of these factors have a largely normal early B cell development. However, when both factors are eliminated simultaneously a block is uncovered at the transition between pre-B and immature B cells, indicating that these proteins exert a critical function in developing B lymphocytes. In mice deficient for Aiolos and OBF-1, the numbers of immature B cells are reduced, small pre-BII cells are increased and a significant impairment in immunoglobulin light chain DNA rearrangement is observed. We identified genes whose expression is deregulated in the pre-B cell compartment of these mice. In particular, we found that components of the pre-BCR, such as the surrogate light chain genes λ5 and VpreB, fail to be efficiently silenced in double-mutant mice. Strikingly, developmentally regulated nuclear repositioning of the λ5 gene is impaired in pre-B cells lacking OBF-1 and Aiolos. These studies uncover a novel role for OBF-1 and Aiolos in controlling the transcription and nuclear organization of genes involved in pre-BCR function

Permanent education in health: a review

OBJECTIVE : To undertake a meta-synthesis of the literature on the main concepts and practices related to permanent education in health. METHODS : A bibliographical search was conducted for original articles in the PubMed, Web of Science, LILACS, IBECS and SciELO databases, using the following search terms: “public health professional education”, “permanent education”, “continuing education”, “permanent education health”. Of the 590 articles identified, after applying inclusion and exclusion criteria, 48 were selected for further analysis, grouped according to the criteria of key elements, and then underwent meta-synthesis. RESULTS : The 48 original publications were classified according to four thematic units of key elements: 1) concepts, 2) strategies and difficulties, 3) public policies and 4) educational institutions. Three main conceptions of permanent education in health were found: problem-focused and team work, directly related to continuing education and education that takes place throughout life. The main strategies for executing permanent education in health are discussion, maintaining an open space for permanent education, and permanent education clusters. The most limiting factor is mainly related to directly or indirect management. Another highlight is the requirement for implementation and maintenance of public policies, and the availability of financial and human resources. The educational institutions need to combine education and service aiming to form critical-reflexive graduates. CONCLUSIONS : The coordination between health and education is based as much on the actions of health services as on management and educational institutions. Thus, it becomes a challenge to implement the teaching-learning processes that are supported by critical-reflexive actions. It is necessary to carry out proposals for permanent education in health involving the participation of health professionals, teachers and educational institutions.OBJETIVO : Realizar metasíntesis de la literatura sobre los principales conceptos y prácticas relacionados con la educación permanente en salud. MÉTODOS : Se realizó búsqueda bibliográfica de artículos originales en las bases de datos PubMed, Web of Science, Lilacs, IBECS y SciELO, utilizando los siguientes descriptores: “ public health professional education”, “permanent education”, “continuing education”, “permanent education health ”. De un total de 590 artículos identificados, posterior a los criterios de inclusión y exclusión, fueron seleccionados 48 para análisis, los cuales fueron sometidos al análisis individual, análisis comparativo, análisis con criterios de agrupamiento de elementos-clave y sometidos a metasíntesis. RESULTADOS : Los 48 artículos originales fueron clasificados como elementos-clave en cuatro unidades temáticas: 1) Concepciones; 2) Estrategias y dificultades; 3) Políticas públicas e 4) Instituciones formadoras. Se encontraron tres concepciones principales de educación permanente en salud: ubicación del problema y enfocarlo en el trabajo en equipo, directamente relacionado con la educación continua y educación que se da a lo largo de la vida. Las principales estrategias para efectivar la educación permanente fueron la ubicación del problema, mantenimiento de espacios para la educación permanente y polos de educación permanente. El mayor factor limitante estuvo relacionado con la gerencia directa o indirecta. Fueron mencionadas la necesidad de implementación y mantenimiento de políticas públicas, así como la disponibilidad de recursos financieros y humanos. Las instituciones formadoras tendrían la necesidad de articular educación y servicio para la formación de egresados críticos-reflexivos. CONCLUSIONES : La articulación educación y salud se encuentra pautada tanto en las acciones de los servicios de salud, cuanto en la gestión y de instituciones formadoras. Así, se torna un desafío implementar procesos de educación-aprendizaje que sean respaldados por acciones crítico-reflexivas. Es necesario realizar propuestas de educación permanente en salud con la participación de profesionales de los servicios, profesores y profesionales de las instituciones de educación.OBJETIVO : Realizar metassíntese da literatura sobre os principais conceitos e práticas relacionados à educação permanente em saúde. MÉTODOS : Foi realizada busca bibliográfica de artigos originais nas bases de dados PubMed, Web of Science, Lilacs, IBECS e SciELO, utilizando os seguintes descritores: “ public health professional education ”, “ permanent education”, “continuing education ”, “ permanent education health ”. De um total de 590 artigos identificados, após os critérios de inclusão e exclusão, foram selecionados 48 para análise, os quais foram submetidos à análise individual, análise comparativa, análise com critérios de agrupamentos de elementos-chave e submetidos à metassíntese. RESULTADOS : Os 48 artigos originais foram classificados como elementos-chave em quatro unidades temáticas: 1) Concepções; 2) Estratégias e dificuldades; 3) Políticas públicas; e 4) Instituições formadoras. Foram encontradas três concepções principais de educação permanente em saúde: problematizadora e focada no trabalho em equipe, diretamente relacionada à educação continuada e educação que se dá ao longo da vida. As principais estratégias para efetivação da educação permanente foram a problematização, manutenção de espaços para a educação permanente e polos de educação permanente. O maior fator limitante foi relacionado à gerência direta ou indireta. Foram indicadas a necessidade de implementação e manutenção de políticas públicas, além de disponibilidade de recursos financeiros e de recursos humanos. As instituições formadoras teriam necessidade de articular ensino e serviço para a formação de egressos críticos-reflexivos. CONCLUSÕES : A articulação educação e saúde encontra-se pautada tanto nas ações dos serviços de saúde, quanto de gestão e de instituições formadoras. Assim, torna-se um desafio implementar processos de ensino-aprendizagem que sejam respaldados por ações crítico-reflexivas. É necessário realizar propostas de educação permanente em saúde com a participação de profissionais dos serviços, professores e profissionais das instituições de ensino

Computational Models of the Notch Network Elucidate Mechanisms of Context-dependent Signaling

The Notch signaling pathway controls numerous cell fate decisions during development and adulthood through diverse mechanisms. Thus, whereas it functions as an oscillator during somitogenesis, it can mediate an all-or-none cell fate switch to influence pattern formation in various tissues during development. Furthermore, while in some contexts continuous Notch signaling is required, in others a transient Notch signal is sufficient to influence cell fate decisions. However, the signaling mechanisms that underlie these diverse behaviors in different cellular contexts have not been understood. Notch1 along with two downstream transcription factors hes1 and RBP-Jk forms an intricate network of positive and negative feedback loops, and we have implemented a systems biology approach to computationally study this gene regulation network. Our results indicate that the system exhibits bistability and is capable of switching states at a critical level of Notch signaling initiated by its ligand Delta in a particular range of parameter values. In this mode, transient activation of Delta is also capable of inducing prolonged high expression of Hes1, mimicking the “ON” state depending on the intensity and duration of the signal. Furthermore, this system is highly sensitive to certain model parameters and can transition from functioning as a bistable switch to an oscillator by tuning a single parameter value. This parameter, the transcriptional repression constant of hes1, can thus qualitatively govern the behavior of the signaling network. In addition, we find that the system is able to dampen and reduce the effects of biological noise that arise from stochastic effects in gene expression for systems that respond quickly to Notch signaling