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The present work was initiated to finalize resin for the development of thermal protection system (TPS) for the external surface of a polymeric composite rocket motor case made up of Carbon roving and Epoxy resin. The temperature on the outer surface of the composite case increases due to kinetic heating caused by aerodynamic drag and vehicle velocity. These rocket motor casings are functionally required only in the ascent phase of missile trajectory till motor action time and stage separation. Due to which the experienced heat flux is relatively less, and the temperature on the external composite case is in order of 250 °C - 300 °C depending on missile configuration & trajectory, unlike extreme thermal conditions on ablative nozzle liners exposed to rocket motor exhaust. The maximum allowable temperature in the present study for the Carbon-Epoxy case is 100 °C due to degradation in mechanical properties. The thermal protection system on the external surface will function as a heat-insulating layer based on the working mechanism of ablation. The resin of the thermal protection layer has a substantial impact on the manufacturing process and curing aspects, especially compatibility with the pre-cured carbon epoxy case layer. The generation of test results for thermal stability, cure characteristics and Tg for Epoxy resin has also been included in present studies as an additional objective that provides significant inputs for process development. The test results for Epoxy resin is also used as a basis for the finalization of resin for the thermal protection layer for processing aspects apart from its basic thermal stability characteristics. The ablative thermal protection working mechanism is based on the ablation phenomenon. In the case of ablation, resin plays a vital role due to pyrolysis and other thermal characteristics. In the present experimental studies, the Phenolic resin and Silicone resin are considered as candidate resin materials for ablative thermal protection system based on available literature and in house experience. The main objective of the present studies is to evaluate thermal stability, char yield after final decomposition through DSC and TGA techniques for both resins as these are fundamental characteristics needed for the present specific application. The test results for specific grades (formulation) of phenolic and Silicone resins are generated and compared. In the present work, the experimental studies to evaluate glass transition temperature (Tg), thermal stability, and cure characteristics for Epoxy resin is also carried through DSC. The test results of specific grade Epoxy resin provides a basis to assess thermal margins for resins selected for ablative thermal protection system and inputs for process development and design requirements. The scope of the present studies is aimed to finalize the resin system for external thermal protection of composite rocket motor case based on thermal characteristics test results and other compatibility aspects with the structural layer. [ABSTRACT FROM AUTHOR]

Background: Various studies have shown that low body mass index co-relates with the severity of Chronic obstructive pulmonary disease. The reduced body mass index in these patients is thought to be due to nutritional abnormality and raised circulating inflammatory markers. The study is aimed to find the association of body mass index with respiratory failure in patient with chronic obstructive pulmunory disease., Methods: 142 patients who attended emergency /out-patient-department in Sir Sundarlal Hospital from August 2018 to July 2020 were enrolled for the study. 81 patients in one group had chronic obstructive pulmonary disease exacerbation with Type II respiratory failure. Among this group low and normal body mass index subgroup was categorized.61 patients in another group had chronic obstructive pulmonary disease. Non-invasive ventilation was applied to case group. Categorization of body mass index was done <18.5(Low BMI) and 18.5-24.9 (Normal BMI )., Results: The mean age of the study group was (63.53±9.021). There was a significant difference in the body mass index between the groups ( p=<0.001,t=15.40). Severity of respiratory failure was compared using ph and pco2 in the between the groups which showed no significant difference (p=1,chi square 0.000), (p=0.40,chi square=0.72) however it did affect the outcome., Conclusions: Our study shows that overall respiratory failure was common in low body mass index cases compared to Control. Nevertheless there was no difference among severity of respiratory failure among low and normal body mass index subgroups and however it did affect the outcome.