Lessons Learned from the Space Shuttle Engine Hydrogen Flow Control Valve Poppet Breakage

The Main Propulsion System (MPS) uses three Flow Control Valves (FCV) to modulate the flow of pressurant hydrogen gas from the Space Shuttle Main Engines (SSME) to the hydrogen External Tank (ET). This maintains pressure in the ullage volume as the liquid level drops, preserving ET structural integrity and assuring the engines receive a sufficient amount of head pressure. On Space Transportation System (STS)-126 (2009), with only a handful of International Space Station (ISS) assembly flights from the end of the Shuttle program, a portion of a single FCV?s poppet head broke off at about a minute and a half after liftoff. The risk of the poppet head failure is that the increased flow area through the FCV could result in excessive gaseous hydrogen flow back to the external tank, which could result in overboard venting of hydrogen ullage pressure. If the hydrogen venting were to occur in first stage (i.e., lower atmosphere), a flammability hazard exists that could lead to catastrophic loss of crew and vehicle. Other failure risks included particle impact damage to MPS downstream hardware. Although the FCV design had been plagued by contamination-related sluggish valve response problems prior to a redesign at STS-80 (1996), contamination was ruled out as the cause of the STS-126 failure. Employing a combination of enhanced hardware inspection and a better understanding of the consequences of a poppet failure, safe flight rationale for subsequent flights (STS-119 and later) was achieved. This paper deals with the technical lessons learned during the investigation and mitigation of this problem at a time when assembly flights were each in the critical path to Space Station success

Rubbing effects on the structural and optical properties of poly(3­hexylthiophene) films

International audienc

Influence of storage environment on maize grain: CO2 production, dry matter losses and aflatoxins contamination

Poor storage of cereals, such as maize can lead to both nutritional losses and mycotoxin contamination. The aim of this study was to examine the respiration of maize either naturally contaminated or inoculated with Aspergillus flavus to examine whether this might be an early and sensitive indicator of aflatoxin (AF) contamination and relative storability risk. We thus examined the relationship between different interacting storage environmental conditions (0.80–0.99 water activity (aw) and 15–35°C) in naturally contaminated and irradiated maize grain + A. flavus on relative respiration rates (R), dry matter losses (DMLs) and aflatoxin B1 and B2 (AFB1-B2) contamination. Temporal respiration and total CO2 production were analysed by GC-TCD, and results used to calculate the DMLs due to colonisation. AFs contamination was quantified at the end of the storage period by HPLC MS/MS. The highest respiration rates occurred at 0.95 aw and 30–35°C representing between 0.5% and 18% DMLs. Optimum AFs contamination was at the same aw at 30°C. Highest AFs contamination occurred in maize colonised only by A. flavus. A significant positive correlation between % DMLs and AFB1 contamination was obtained (r = 0.866, p < 0.001) in the irradiated maize treatments inoculated with A. flavus. In naturally contaminated maize + A. flavus inoculum loss of only 0.56% DML resulted in AFB1 contamination levels exceeding the EU legislative limits for food. This suggests that there is a very low threshold tolerance during storage of maize to minimise AFB1 contamination. This data can be used to develop models that can be effectively used in enhancing management for storage of maize to minimise risks of mycotoxin contamination

Estabilidade da cor de doces em massa de polpa de umbu (Spondias Tuberosa Arr. Cam.) no estádio de maturação verde.

Os frutos de umbu (Spondias tuberosa Arr. Cam.) maduros são altamente perecíveis, e o aproveitamento deles no estádio de maturação verde, sob a forma de doce é uma interessante alternativa econômica, para o semi-árido nordestino. A conservação da cor, durante o armazenamento, constitui um fator de qualidade dos mais importantes para o consumo, e o presente trabalho objetivou avaliar sua alteração em função de diferentes formulações, embalagens (polipropileno e celofane) e temperaturas (33 e 43°C), por 90 dias de armazenamento. A adição de pectina e/ou xarope de glicose não alterou a luminosidade (L*), mas diminuiu os valores de a* (intensidade do vermelho ) e b*. (intensidade do amarelo). Verificou-se diminuição dos valores de L* a* e b*, notadamente para os doces armazenados à temperatura de 43°C e para a formulação sem adição de pectina. A embalagem não exerceu efeito significativo sobre L*( luminosidade), mas afetou a* e b* aos 90 dias de estocagem, em ambas as temperaturas. Os resultados globais indicaram o uso de pectina e xarope de glicose, embalagens de polipropileno e estocagem à temperaturas mais baixas como sendo as condições mais adequadas para preservação da cor

A saúde como tema do componente curricular Educação Física no Referencial Curricular “Lições do Rio Grande”

The present article aims to analyze how the health theme is approached in Rio Grande do Sul Curriculum Reference – Lessons from Rio Grande, specifically in the Physical Education curricular component. From the analysis of the texts that refer to Physical Education in the referential and the books of teacher and student, some considerations could be made: the displacement of the health theme from a dimension of know-how to know-about; an expanded conception of health in terms of its different dimensions; health as a content in different structuring themes of the proposed curriculum for Physical Education.El presente artículo tiene como objetivo analizar de qué manera el tema salud se aborda en el marco curricular de Rio Grande do Sul - Lecciones del Río Grande, más específicamente en el componente curricular Educación Física. A partir del análisis de los textos que versan sobre Educación Física en el marco curricular y de los cuadernos del profesor y del alumno, algunas consideraciones pudieron ser hechas: el cambio del tema salud de una dimensión del saber-hacer para el saber-sobre; una concepción ampliada sobre salud, con respecto a sus diferentes dimensiones; la salud como contenido en diferentes temas estructurantes del plan de estudios propuesto para Educación Física.O presente artigo tem como objetivo analisar de que maneira o tema saúde é abordado no Referencial Curricular do Rio Grande do Sul – Lições do Rio Grande, mais especificamente no componente curricular Educação Física. A partir da análise dos textos que versam sobre Educação Física no referencial e dos cadernos do professor e do aluno, algumas considerações puderam ser feitas: o deslocamento do tema saúde de uma dimensão do saber-fazer para o saber-sobre; uma concepção ampliada sobre saúde, no tocante às suas diferentes dimensões; a saúde enquanto um conteúdo em diferentes temas estruturantes do currículo proposto para a Educação Física

VCU College of Humanities and Sciences Racial Equity Assessment

Racial equity is the process of ensuring that equal possible outcomes are available for every individual. At the College of Humanities and Sciences (CHS) an important goal is to ensure faculty and staff have access to the same opportunities, while accounting for those facing continued barriers. Following the establishment of the Inclusion, Diversity and Equity Committee, the current state of racial equity and the effectiveness of initiatives meant to correct for imbalance will be assessed

Variedades de tomates nacionales

En el Cinturón Hortícola Platense se producen numerosas especies hortícolas, entre los cultivos más importantes se encuentra el tomate. Dentro de este cultivo existen numerosos híbridos de origen importado y variedades nacionales. Con respecto a estas últimas, el INTA La Consulta y la FCAyF-UNLP han trabajado muchos años para crear variedades que se adapten a diferentes condiciones agroecológicas del país y a las necesidades de los productores hortícolas.Facultad de Ciencias Agrarias y Forestales (FCAF

Variedades de tomates nacionales

En el Cinturón Hortícola Platense se producen numerosas especies hortícolas, entre los cultivos más importantes se encuentra el tomate. Dentro de este cultivo existen numerosos híbridos de origen importado y variedades nacionales. Con respecto a estas últimas, el INTA La Consulta y la FCAyF-UNLP han trabajado muchos años para crear variedades que se adapten a diferentes condiciones agroecológicas del país y a las necesidades de los productores hortícolas.Facultad de Ciencias Agrarias y Forestales (FCAF