Influence of cerium oxide additive and aloe vera biodiesel on a CI engine

Diesel is the main source of world transportation due to higher combustion efficiency, compliance, consistency and cost-economy. It is also a major contributor to the world prosperity since it is used extensively. Diesel engine’s emissions are the serious hazard to the world environment and it is measured to be the major causes of air pollution. The demand in biofuels for years created a scope for aloe vera into biodiesels. Aloe vera, having higher calorific value vnthan other plant sources used as biodiesels, enhanced us in making another alternative biodiesel, which has lesser emissions and better performance. In this research work, four biodiesel blends from aloe vera oil with cerium oxide additive are explored for their performance and emission characteristics. The results proved B30 (30% biodiesel, 68% diesel and 1% cerium oxide) gives good performance when compared to other blends.     

Atherosclerosis, vascular remodeling, and impairment of endothelium-dependent relaxation in genetically altered hyperlipidemic mice

We examined the vascular structure and endothelium-dependent relaxation in two genetic models of hypercholesterolemia: apolipoprotein E (apoE)-knockout mice and combined apoE/LDL receptor-double-knockout mice. Intimal area was increased markedly in proximal segments of thoracic aortas from apoE/LDL receptor-knockout mice [0.13 +/- 0.03 (mean +/- SE) mm2] compared with normal (C57BL/6J) mice (0.002 +/- 0.002 mm2, P < .05). Despite intimal thickening, the vascular lumen was not smaller in the aortas of apoE/LDL receptor-knockout mice (0.52 +/- 0.03 mm2) than in normal mice (0.50 +/- 0.03 mm2). In apoE-deficient mice, intimal thickening was minimal or absent, even though the concentration of plasma cholesterol was only modestly less than that in the double-knockout mouse (14.9 +/- 1.1 vs 18.0 +/- 1.2 mmol/L, respectively, P < .05). Relaxation of the aorta was examined in vitro in vascular rings precontracted with U46619. In normal mice, acetylcholine produced relaxation, which was markedly attenuated by the nitric oxide synthase inhibitor NG-nitro-L-arginine (100 microM). Relaxation to acetylcholine and the calcium ionophore A23187 was normal in apoE-deficient mice (in which lesions were minimal) but greatly impaired in the proximal segments of thoracic aortas of apoE/LDL receptor-deficient mice, which contained atherosclerotic lesions. Vasorelaxation to nitroprusside was similar in normal and apoE-knockout mice, with modest but statistically significant impairment in atherosclerotic segments of apoE/LDL receptor-knockout mice. In distal segments of the thoracic aorta of apoE/LDL receptor-deficient mice, atherosclerotic lesions were minimal or absent, and the endothelium-dependent relaxation to acetylcholine and calcium ionophore was normal. Thus, in apoE/LDL receptor-knockout mice (a genetic model of hyperlipidemia), there is vascular remodeling with preservation of the aortic lumen despite marked intimal thickening, with impairment of endothelium-dependent relaxation to receptor- and nonreceptor-mediated agonists. Atherosclerosis may be accelerated in the apoE/LDL receptor-double-knockout mouse compared with the apoE-knockout strain alone. We speculate that other factors, such as the absence of LDL receptors, may contribute to the differences in the extent of atherosclerosis in these two models of hyperlipidemia.     

An investigation of dielectric material selection of RF-MEMS switches using Ashby’s methodology for RF applications

This paper presents a dielectric material selection methodology for RF-MEMS switch used for radio frequency applications. Here Ashby’s material selection approach is used to optimize the performance indices of RF-MEMS switch such as dielectric charging, stability, hold down voltage and RF performance. In this work, dielectric constant (ɛ _r), electrical resistivity (ρ), thermal conductivity (λ), thermal expansion coefficient (α), Young’s Modulus (E) are chosen as material indices of dielectric layer in RF-MEMS switch to evaluate the various performance indices. The Ashby’s material selection charts shows that Al₂O₃ and SiN are the best suitable material for dielectric layer in RF-MEMS switches to exhibit improved performance for radio frequency applications.