Clemson University

About: Clemson University is a education organization based out in Clemson, South Carolina, United States. It is known for research contribution in the topics: Population & Control theory. The organization has 20556 authors who have published 42518 publications receiving 1170779 citations. The organization is also known as: Clemson Agricultural College of South Carolina.

Transesterification of triacetin with methanol on solid acid and base catalysts

Abstract: Biodiesel is a particularly attractive renewable fuel as it can be used in existing engines, is environmentally friendly, and is readily synthesized from animal fats and vegetable oils. Heterogeneous catalysts offer exciting possibilities for improving the economics of biodiesel synthesis; however, few published investigations have addressed the use of such catalysts to date. The purpose of this research was to investigate the kinetics and selectivities of different solid catalysts for the transesterification of triacetin (a model compound for larger triglycerides as found in vegetable oils and fats) with methanol. Reaction was carried out at 60 °C in a batch reactor with a variety of solid and liquid, acid and base catalysts. The homogeneous phase (i.e., liquid) catalysts (NaOH and H2SO4) were studied for comparison. Amberlyst-15, Nafion NR50, sulfated zirconia, and ETS-10 (Na, K) showed reasonable activities, suggesting that they could be suitable alternatives to liquid catalysts. While on a wt.% basis (of reaction mixture) the homogeneous phase catalysts gave higher rates of reaction, on a rate-per-site basis the solid acids were similar to H2SO4. Sulfated zirconia and tungstated zirconia had comparable turnover frequencies as H2SO4. The deactivation characteristics of some of these catalysts were also studied.

A continuous asymptotic tracking control strategy for uncertain nonlinear systems

Abstract: In this note, we present a new continuous control mechanism that compensates for uncertainty in a class of high-order, multiple-input-multiple-output nonlinear systems. The control strategy is based on limited assumptions on the structure of the system nonlinearities. A new Lyapunov-based stability argument is employed to prove semiglobal asymptotic tracking.

Cannabinoids control spasticity and tremor in a multiple sclerosis model.

Abstract: Chronic relapsing experimental allergic encephalomyelitis (CREAE) is an autoimmune model of multiple sclerosis1. Although both these diseases are typified by relapsing-remitting paralytic episodes, after CREAE induction by sensitization to myelin antigens1 Biozzi ABH mice also develop spasticity and tremor. These symptoms also occur during multiple sclerosis and are difficult to control. This has prompted some patients to find alternative medicines, and to perceive benefit from cannabis use2. Although this benefit has been backed up by small clinical studies, mainly with non-quantifiable outcomes3,4,5,6,7, the value of cannabis use in multiple sclerosis remains anecdotal. Here we show that cannabinoid (CB) receptor agonism using R(+)-WIN 55,212, Δ9-tetrahydrocannabinol, methanandamide and JWH-133 (ref. 8) quantitatively ameliorated both tremor and spasticity in diseased mice. The exacerbation of these signs after antagonism of the CB1 and CB2 receptors, notably the CB1 receptor, using SR141716A and SR144528 (ref. 8) indicate that the endogenous cannabinoid system may be tonically active in the control of tremor and spasticity. This provides a rationale for patients' indications of the therapeutic potential of cannabis in the control of the symptoms of multiple sclerosis2, and provides a means of evaluating more selective cannabinoids in the future.