Buoyancy Effects on Concurrent Flame Spread Over Thick PMMA

The flammability of combustible materials in a spacecraft is important for fire safety applications because the conditions in spacecraft environments differ from those on earth. Experimental testing in space is difficult and expensive. However, reducing buoyancy by decreasing ambient pressure is a possible approach to simulate on-earth the burning behavior inside spacecraft environments. The objective of this work is to determine that possibility by studying the effect of pressure on concurrent flame spread, and by comparison with microgravity data, observe up to what point low-pressure can be used to replicate flame spread characteristics observed in microgravity. Specifically, this work studies the effect of pressure and microgravity on upward/concurrent flame spread over 10 mm thick polymethyl methacrylate (PMMA) slabs. Experiments in normal gravity were conducted over pressures ranging between 100 and 40 kPa and a forced flow velocity of 200 mm/s. Microgravity experiments were conducted during NASAs Spacecraft Fire Experiment (Saffire II), on board the Cygnus spacecraft at 100 kPa with an air flow velocity of 200 mm/s. Results show that reductions of pressure slow down the flame spread over the PMMA surface approaching that in microgravity. The data is correlated in terms of a non-dimensional mixed convection analysis that describes the convective heat transferred from the flame to the solid, and the primary mechanism controlling the spread of the flame. The extrapolation of the correlation to low pressures predicts well the flame spread rate obtained in microgravity in the Saffire II experiments. Similar results were obtained by the authors with similar experiments with a thin composite cotton/fiberglass fabric (published elsewhere). Both results suggest that reduced pressure can be used to approximately replicate flame behavior of untested gravity conditions for the burning of thick and thin solids. This work could provide guidance for potential ground-based testing for fire safety design in spacecraft and space habitats

On Simulating Concurrent Flame Spread in Reduced Gravity by Reducing Ambient Pressure

The flammability of combustible materials in spacecraft environments is of importance for fire safety applications because the environmental conditions can greatly differ from those on earth, and a fire in a spacecraft could be catastrophic. Moreover, experimental testing in spacecraft environments can be difficult and expensive, so using ground-based tests to inform microgravity tests is vital. Reducing buoyancy effects by decreasing ambient pressure is a possible approach to simulate a spacecraft environment on earth. The objective of this work is to study the effect of pressure on material flammability, and by comparison with microgravity data, determine the extent to which reducing pressure can be used to simulate reduced gravity. Specifically, this work studies the effect of pressure and microgravity on upward/concurrent flame spread rates and flame appearance of a burning thin composite fabric made of 75% cotton and 25% fiberglass (Sibal). Experiments in normal gravity were conducted using pressures ranging between 100 and 30 kPa and a forced flow velocity of 20 cm/s. Microgravity experiments were conducted during NASAs Spacecraft Fire Experiment (Saffire), on board of the Orbital Corporation Cygnus spacecraft at 100 kPa and an air flow velocity of 20 cm/s. Results show that reductions of ambient pressure slow the flame spread over the fabric. As pressure is reduced, flame intensity is also reduced. Comparison with the concurrent flame spread rates in microgravity show that similar flame spread rates are obtained at around 30 kPa. The normal gravity and microgravity data is correlated in terms of a mixed convection non-dimensional parameter that describes the heat transferred from the flame to the solid surface. The correlation provides information about the similitudes of the flame spread process in variable pressure and reduced gravity environments, providing guidance for potential on-earth testing for fire safety design in spacecraft and space habitats

Regulatory crosstalk by protein kinases on CFTR trafficking and activity

Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) is a member of the ATP binding cassette (ABC) transporter superfamily that functions as a cAMP-activated chloride ion channel in fluid-transporting epithelia. There is abundant evidence that CFTR activity (i.e., channel opening and closing) is regulated by protein kinases and phosphatases via phosphorylation and dephosphorylation. Here, we review recent evidence for the role of protein kinases in regulation of CFTR delivery to and retention in the plasma membrane. We review this information in a broader context of regulation of other transporters by protein kinases because the overall functional output of transporters involves the integrated control of both their number at the plasma membrane and their specific activity. While many details of the regulation of intracellular distribution of CFTR and other transporters remain to be elucidated, we hope that this review will motivate research providing new insights into how protein kinases control membrane transport to impact health and disease.Work supported by the Portuguese Fundação para a Ciência e Tecnologia (fellowship grant SFRH/BSAB/105741/2014—to CF, grant PTDC/SAU-ORG/119782/2010—to PJ, and centre grant UID/MULTI/04046/2013—to BioISI); Gilead Génese PGG/039/2014 and ERS Romain Pauwels 2012 (to CF); CFF SWIATE14P0 (to AS); NIH NIDDK P30 072506 Basic and Translational Studies of Cystic Fibrosis (P&F to AS)

Piloted Ignition Delay of PMMA in Space Exploration Atmospheres

In order to reduce the risk of decompression sickness associated with extravehicular activity (EVA), NASA is designing the next generation of exploration vehicles and habitats with a different cabin environment than used previously. The proposed environment uses a total cabin pressure of 52.7 to 58.6 kPa with an oxygen concentration of 30 to 34% by volume and was chosen with material flammability in mind. Because materials may burn differently under these conditions and there is little information on how this new environment affects the flammability of the materials onboard, it is important to conduct material flammability experiments at the intended exploration atmosphere. One method to evaluate material flammability is by its ease of ignition. To this end, piloted ignition delay tests were conducted in the Forced Ignition and Spread Test (FIST) apparatus subject to this new environment. In these tests, polymethylmethacylate (PMMA) was exposed to a range of oxidizer flow velocities and externally applied heat fluxes. Tests were conducted for a baseline case of normal pressure and oxygen concentration, low pressure (58.6 kPa) with normal oxygen (21%), and low pressure with 32% oxygen concentration conditions to determine the individual effect of pressure and the combined effect of pressure and oxygen concentration on the ignition delay. It was found that reducing the pressure while keeping the oxygen concentration at 21% reduced the ignition time by 17% on average. Increasing the oxygen concentration at low pressures reduced the ignition time by an additional 10%. It was also noted that the critical heat flux for ignition decreases at exploration atmospheres. These results show that tests conducted in standard atmospheric conditions will underpredict the ignition of materials intended for use on spacecraft and that, at these conditions, materials are more susceptible to ignition than at current spacecraft atmospheres

Paulo Freire's contributions in teacher training for Youth and Adult Education: an analysis of scientific production from the perspective of Methodi Ordinatio

Este artigo, na forma de pesquisa de revisão bibliográfica sistemática, objetiva identificar a produção científica referente à contribuição de Paulo Freire para a formação de professores, na modalidade de Educação de Jovens e Adultos, EJA. A pesquisa foi realizada com a metodologia denominada Methodi Ordinatio. A questão norteadora foi: Quais as contribuições de Paulo Freire para a formação de professores da modalidade de educação de jovens e adultos? Do ponto de vista da problemática, a pesquisa se caracteriza como de cunho qualitativo, pois visa conhecer o que a literatura apresenta sobre as questões centrais do tema. Como resultado do levantamento, obteve-se, inicialmente, 182 (cento e oitenta e dois) artigos. Após o processo de filtragem e eliminação de duplicatas e títulos não pertencentes à área de pesquisa, restaram 105 (cento e cinco) artigos; dos quais foram lidos o título e o resumo, e verificou-se que 10 (dez) artigos se referem aos temas, em conjunto: formação de professores, educação de jovens e adultos e Paulo Freire. Constatou-se as contribuições de Paulo Freire para a EJA e que existem possibilidades de pesquisa direcionando essas contribuições para a formação de professores nessa modalidade de ensino.This article, in the form of a systematic bibliographic review research, aims to identify the scientific production on the theme of Paulo Freire's contribution to teacher education, in the form of Youth and Adult Education. The research was carried out with the methodology called Methodi Ordinatio. The guiding question was: What are Paulo Freire's contributions to the training of teachers in the youth and adult education modality? From the point of view of the issue, it is characterized by a qualitative nature, as it seeks to know what the literature puts on the central issues of the theme. As a result of the survey, initially 182 articles were obtained, after the process of filtering and eliminating duplicates and titles outside the research area, 105 articles remained. Of these 105, the title and abstract were read and 10 articles referred to teacher training, youth and adult education and Paulo Freire. It was observed in this study that there are research possibilities when directed to the contributions of Paulo Freire with the training of teachers for the education of young people and adults