Search

Base drag is arising from flow separation at blunt base of a body. It can be a sizeable fraction of total drag in context of projectiles, missiles and after bodies of fighter aircrafts. The base drag is the major contribution of total drag for low speed regimes. Flight tests have shown that the base drag may account for up to 50% of total drag. In this paper an experimental work on a simple semi-circular flight vehicle body of length 500mm and diameter 50mm was conducted for the purpose of investigating base drag. The base drags for three configurations are calculated and the results are compared with CFD data. The three configurations used for testing are flat base configuration, closed nozzle configuration and boat tail configuration. The evaluations of base drag for the flow velocities of 20m/s, 35m/s and 50m/s at angles of attack such as -2, 0 and 2 are experimented and compared. [ABSTRACT FROM AUTHOR]

Base drag is arising from flow separation at blunt base of a body. It can be a sizeable fraction of total drag in context of projectiles, missiles and after bodies of fighter aircrafts. The base drag is the major contribution of total drag for low speed regimes. Flight tests have shown that the base drag may account for up to 50% of total drag. In this paper an experimental work on a simple semi-circular flight vehicle body of length 500mm and diameter 50mm was conducted for the purpose of investigating base drag. The base drags for three configurations are calculated and the results are compared with CFD data. The three configurations used for testing are flat base configuration, closed nozzle configuration and boat tail configuration. The evaluations of base drag for the flow velocities of 20m/s, 35m/s and 50m/s at angles of attack such as -2 °, 0 ° and 2 ° are experimented and compared. [ABSTRACT FROM AUTHOR]

This research article provides the results obtained from comparative studies on the technical performance of some selected rice milling machines. There is a continuous and increasing demand for high quality rice production. This can be achieved by optimization of the rice milling process. Hence, we have studied the wear patterns in major machine components of three different brands of rice polishers. Here we have carried out a wear analysis and studied the processing mechanisms of rice milling machines. We have attempted to set a benchmark for wear resistance to design alternative materials, which can improve the wear life of cam, which acts as the major component in rice mills. [ABSTRACT FROM AUTHOR]

Graphene when mixed in small quantity to host matrix like epoxy improves the mechanical, thermal and electrical properties. Fabrication of natural composite is made with goat hair as fibre with 37.5% fibre content by weight and graphene filled epoxy as matrix to enhance the properties. In the process of composite fabrication, five layers of goat hair fibre is sandwiched using resin by compression moulding method. Four composite specimens respectively epoxy with no Graphene content and 0.25% to 0.75% Graphene filled epoxy matrix are tested for tensile strength, flexural strength, impact strength and hardness. The mechanical properties of the four composite specimens are analysed. The experimental test results have demonstrated that graphene filled epoxy matrix reinforced with goat hair fibre specimens had better mechanical properties than composite with no graphene content. [ABSTRACT FROM AUTHOR]

Lipases are important biocatalysts showing many interesting properties with industrial applications. Previously, different isoforms of lipases, Lipase-I and Lipase-II from rice (Oryza sativa) have been purified and characterized. Lipase-II identified as the major lipase in rice bran is designated as rice bran lipase (RBL). In this study, we report the cloning and expression of the RBL in Escherichia coli and Pichia pastoris. An exploration of expression in four different E. coli expression systems analyzed: BL21(DE3)pLysS, RIL(DE3)pLysS, Rosetta(DE3)pLysS and Origami(DE3)pLysS indicated that E. coli was not a suitable host. Expression with supplement of rare codons in Rosetta (DE3)pLysS and RIL(DE3)pLysS resulted in highest expression as insoluble inclusion bodies. The hurdles of expression in E. coli were overcome by expression as a secretory protein in P. pastoris X-33. The expression of lipase in shake flasks was optimized to achieve the maximum recombinant lipase activity of 152.6 U/mL. The purified recombinant lipase had a specific activity of 998 U/mg toward triacetin. The pH and temperature optimum of native and recombinant enzymes were pH 7.4 and 25 ± 2 °C, respectively. Both the lipases showed higher activity toward short chain triacylglycerol and unsaturated fatty acid enriched oils. Computational modeling and molecular docking studies reveal that the catalytic efficiency of the lipase correlates with the distance of the nucleophilic Ser(175)-OH and the scissile ester bond. The shorter the distance, the greater is the turnover of the substrate., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Lipolytic enzymes play an important role in plant growth and development. In order to identify their functional roles, the temporal expression profiling of lipase was carried out during rice seed germination, growth and development of caryopsis. Changes in specific activities during germination revealed that the lipolytic activity increased significantly until the end of germination. As the lipase activity increased, two different lipase species were observed, which were designated as Lipase-I and Lipase-II based on their relative mobility. Lipase-II was active during germination. Lipase-I was responsible for lipid mobilization, a requirement for the growth of root and shoot. In comparison with the endosperm, the lipolytic activity in roots was three fold higher. During rice caryopsis development, the lipolytic activity increased gradually from initial panicle development and reached maximum as the grain dried to harvest maturity. Quantitative real-time PCR analysis revealed that the Lipase-II was a stage specific expressing gene during reproductive growth. The transcript level of Lipase-II reached maximum with completion of germination, then decreased and remained stable during post-germinative growth. During caryopsis development, Lipase-II is predominantly expressed in the developing seeds. The transcript abundance increased gradually during initial stages of development and reached a maximum until seed maturation. The results implicate that the dynamic changes in the enzyme activity of the two isoforms of lipase and gene expression patterns are associated with the energy reserve mobilization during seed germination and reproductive growth., (Copyright © 2012 Elsevier Masson SAS. All rights reserved.)