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The objective of this research is to study for the first time the effect of adding L-arginine (Arg) amino acid on the solubility of carbon dioxide in aqueous solution of N-methyldiethanolamine (MDEA). The study was carried out at different mixing ratios of MDEA and Arg at a total concentration of 2 moles per litre. The CO 2 partial pressure varied from about 10 to 100 kPa, and the temperature varied from 293 K to 323 K. The experimental results showed improved solubility of CO 2 with the addition of Arg at CO 2 partial pressures below 20 kPa. However, for CO 2 partial pressure of above 20 kPa, the addition of Arg caused a decrease in the solubility of CO 2 . The obtained loading data were correlated using a semiempirical (SE) vapour liquid equilibrium (VLE) model with an average absolute deviation (AAD) less than 4.1% between the predicted and the experimental values. An estimation of the heat of CO 2 absorption in the solution was obtained using an analytical expression for ΔH abs derived from the SE model and was found to be in the range of 29-to 40-kJ/mole CO 2 . From the finding of this work, it is anticipated that the studied novel blended solvent will effectively reduce CO 2 capture costs as the CO 2 content of most gas streams is less than 20% by volume, which is specifically true for natural gas and a large number of industrial flue gas streams.

In this study, we develop and characterize an asbestos-free rubber composite for potential use as a rocket motor insulator. The insulator is based on ethylene propylene diene monomer blended with aramid fiber (Kevlar) in the pulp form (KP), together with alumina and/or silica as reinforcement. Different formulations based on these fillers were prepared. The fillers were dispersed in the ethylene propylene diene monomer polymeric matrix to obtain a homogenous master batch for curing. We analyzed and compared physical, mechanical and thermal properties of different compositions (density, hardness, tensile strength, elongation, ablation resistance and mass loss on heating). Reinforcement of ethylene propylene diene monomer with Kevlar improves the performance of the material with respect to mechanical and thermal properties, while not improving well the performance with respect to ablation resistance. Using hybrid reinforcement (KP + alumina + silica) within ethylene propylene diene monomer improves the performance of ethylene propylene diene monomer with respect to mechanical properties, thermal properties, ablation resistance and thermal decomposition resistance. The optimum performance of the insulation material was achieved when the formulation consisted of 10 part per hundred ratio KP with even amounts of alumina and silica. A novel composite engineered for improved insulation of solid rocket motors using the hybrid reinforcements was developed for the first time, which can be applied in future space missions.

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Introduction:The main aim of root canal therapy is adequate sealing to prevent reinfection with subsequent periapical disease.The aim: The aim of this study was to compare the sealing ability of root canal filled teeth using three different sealers and three different restorative materials by bacterial penetration method during a 30-day period.Materials and Methods: Seventy-two single rooted teeth were prepared using Protaper Next. Obturation was done using single cone technique .The teeth were randomly divided into three groups of 24 samples according to the sealer used as following; group 1: Bioceramic sealer (BS), group 2: MTA fillapex (MTA) and group 3: Tagdseal sealer (TG). The samples then randomly subdivided into 3 groups of 8 samples according to the coronal restoration of the specimens as following; subgroup A: Composite (Tetric Ceram + Tetric N Bond), subgroup B: Compomer (Compoglass F + Adhese SE) and subgroup C:Glass Ionomer (Ketac N + Ketac primer).Therefore, there was 9 final groups; I, II, III, IV, V, VI, VII, VIII, IX.After setting time, the samples were incorporated in a bacterial leakage model, using E. faecalis. Leakage was evaluated by turbidity in lower chamber in 30-day period. Statistical analysis was done using One-wayANOVA test, and post hoc pairwise comparison was done using Tukey test. Results:The results showed that group I (BS -Composite) presented the lowest means of bacterial leakage after all periods of evaluation. On the other hand, the (MTA -Glass Ionomer) material showed the highest means of leakage. There was a significant difference between the means of the bacterial colonies recorded in the nine groups at one, 2 and 4 weeks; while at 3 weeks the difference was insignificant. Conclusion :Bioceramic sealer with composite restoration showed the least bacterial leakage.

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