Fire resistivity and toxicity studies of candidate aircraft passenger seat materials

Fire resistivity studies were conducted on a wide range of candidate nonmetallic materials being considered for the construction of improved fire resistant aircraft passenger seats. These materials were evaluated on the basis of FAA airworthiness burn and smoke generation tests, colorfastness, limiting oxygen index, and animal toxicity tests. Physical, mechanical, and aesthetic properties were also assessed. Candidate seat materials that have significantly improved thermal response to various thermal loads corresponding to reasonable fire threats as they relate to in-flight fire situations, are identified

Intermediation in Foreign Trade: When do Exporters Rely on Intermediaries?

The paper explores theoretically and empirically why trade intermediaries (TIs) are frequently used as agents for exports to some countries but not to others. We adapt a standard intra-industry trade model with variable export costs (e.g. transport) and fixed export costs (e.g. market access) to include a TI that is able to pool market access cost. From this framework explanatory factors for the TI share in a countryÕs exports are derived and subsequently tested with a new data set based on French customs information. The paper finds that: (i) higher market access costs increase the TI share, (ii) smaller export markets feature a larger TI share, (iii) the TI share is independent from variable (distance-dependent) export costs.trade intermediation, indirect exports, monopolistic competition

Intermediation in Foreign Trade: When Do Exporters Rely on Intermediaries?

The paper explores theoretically and empirically why trade intermediaries (TIs) are frequently used as agents for exports to some countries but not to others. We adapt a standard intra-industry trade model with variable export costs (e.g. transport) and fixed export costs (e.g. market access) to include a TI that is able to pool market access cost. From this framework explanatory factors for the TI share in a country's exports are derived and subsequently tested with a new data set based on French customs information. The paper finds that: (i) higher market access costs increase the TI share, (ii) smaller export markets feature a larger TI share, (iii) the TI share is independent from variable (distance-dependent) export costs.trade intermediation, indirect exports, transaction costs, monopolistic competition

Study to develop improved fire resistant aircraft passenger seat materials

The Phase 3 study of the NASA 'Improved Fire Resistant Aircraft Seat Materials' involved fire tests of improved materials in multilayered combinations representative of cushion configurations. Tests were conducted to determine their thermal, smoke, and fire resistance characteristics. Additionally, a 'Design Guideline' for Fire Resistant Passenger Seats was written outlining general seat design considerations. Finally, a three-abreast 'Tourist Class' passenger seat assembly fabricated from the most advanced fire-resistant materials was delivered

Release-rate calorimetry of multilayered materials for aircraft seats

Multilayered samples of contemporary and improved fire resistant aircraft seat materials (foam cushion, decorative fabric, slip sheet, fire blocking layer, and cushion reinforcement layer) were evaluated for their rates of heat release and smoke generation. Top layers (decorative fabric, slip sheet, fire blocking, and cushion reinforcement) with glass fiber block cushion were evaluated to determine which materials based on their minimum contributions to the total heat release of the multilayered assembly may be added or deleted. Top layers exhibiting desirable burning profiles were combined with foam cushion materials. The smoke and heat release rates of multilayered seat materials were then measured at heat fluxes of 1.5 and 3.5 W/sq cm. Choices of contact and silicone adhesives for bonding multilayered assemblies were based on flammability, burn and smoke generation, animal toxicity tests, and thermal gravimetric analysis. Abrasion tests were conducted on the decorative fabric covering and slip sheet to ascertain service life and compatibility of layers

Changes in depressive symptoms, perceived stres, and food security among study participants with metabolic syndrome during a COVID-19-mandated research pause

Introduction: This study explored how food security, perceived stress and mental health of persons with metabolic syndrome (MetS) changed in the COVID-19 pandemic. Methods: An online survey was administered to persons enrolled in a 2-year lifestyle intervention trial to reverse metabolic syndrome at baseline; the survey was repeated during the COVID-19 pandemic. Outcomes were a change in depressive symptoms, perceived stress, and food security as measured by the Patient Health Questionnaire-8, Cohen Stress Scale, and USDA 10-item Food Security Screener. Changes in outcomes were analyzed with measures of association, paired t-test, repeated measures and independent t-test. Results: Participants (n = 132; MetS diagnosis) were mostly female (67%), White (70%), middle-aged, well-educated, with median income of $86,000. Perceived stress was significantly higher at baseline than follow-up (18.5 ± 6.4 vs. 14.9 ± 7.2; P Conclusion: A high-risk sample for COVID-19 did not experience increased stress or food insecurity, but demonstrated increased depressive symptoms after the onset of COVID-19 pandemic, with some baseline susceptibility noted

Biological CO2-methanation: An approach to standardization

Power-to-Methane as one part of Power-to-Gas has been recognized globally as one of the key elements for the transition towards a sustainable energy system. While plants that produce methane catalytically have been in operation for a long time, biological methanation has just reached industrial pilot scale and near-term commercial application. The growing importance of the biological method is reflected by an increasing number of scientific articles describing novel approaches to improve this technology. However, these studies are diffcult to compare because they lack a coherent nomenclature. In this article, we present a comprehensive set of parameters allowing the characterization and comparison of various biological methanation processes. To identify relevant parameters needed for a proper description of this technology, we summarized existing literature and defined system boundaries for Power-to-Methane process steps. On this basis, we derive system parameters providing information on the methanation system, its performance, the biology and cost aspects. As a result, three different standards are provided as a blueprint matrix for use in academia and industry applicable to both, biological and catalytic methanation. Hence, this review attempts to set the standards for a comprehensive description of biological and chemical methanation processes

Molecular crowding defines a common origin for the Warburg effect in proliferating cells and the lactate threshold in muscle physiology

Aerobic glycolysis is a seemingly wasteful mode of ATP production that is seen both in rapidly proliferating mammalian cells and highly active contracting muscles, but whether there is a common origin for its presence in these widely different systems is unknown. To study this issue, here we develop a model of human central metabolism that incorporates a solvent capacity constraint of metabolic enzymes and mitochondria, accounting for their occupied volume densities, while assuming glucose and/or fatty acid utilization. The model demonstrates that activation of aerobic glycolysis is favored above a threshold metabolic rate in both rapidly proliferating cells and heavily contracting muscles, because it provides higher ATP yield per volume density than mitochondrial oxidative phosphorylation. In the case of muscle physiology, the model also predicts that before the lactate switch, fatty acid oxidation increases, reaches a maximum, and then decreases to zero with concomitant increase in glucose utilization, in agreement with the empirical evidence. These results are further corroborated by a larger scale model, including biosynthesis of major cell biomass components. The larger scale model also predicts that in proliferating cells the lactate switch is accompanied by activation of glutaminolysis, another distinctive feature of the Warburg effect. In conclusion, intracellular molecular crowding is a fundamental constraint for cell metabolism in both rapidly proliferating- and non-proliferating cells with high metabolic demand. Addition of this constraint to metabolic flux balance models can explain several observations of mammalian cell metabolism under steady state conditions