Topic
Stearate
About: Stearate is a research topic. Over the lifetime, 2983 publications have been published within this topic receiving 36137 citations. The topic is also known as: stearate.
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TL;DR: In this article, the zinc stearate immobilized on silica gel (ZS/Si) was the most effective catalyst in simultaneously catalyzing the transesterification of triglycerides and esterification of free fatty acid (FFA) present in WCO to methyl esters.
Abstract: Various solid acid catalysts were evaluated for the production of biodiesel from low quality oil such as waste cooking oil (WCO) containing 15 wt.% free fatty acids. The zinc stearate immobilized on silica gel (ZS/Si) was the most effective catalyst in simultaneously catalyzing the transesterification of triglycerides and esterification of free fatty acid (FFA) present in WCO to methyl esters. The optimization of reaction parameters with the most active ZS/Si catalyst showed that at 200 °C, 1:18 oil to alcohol molar ratio and 3 wt.% catalysts loading, a maximum ester yield of 98 wt.% could be obtained. The catalysts were recycled and reused many times without any loss in activity.
472 citations
TL;DR: Low concentrations of the long-chain fatty acids oleate and stearate inhibited all steps of the anaerobic thermophilic biogas process during digestion of cattle manure, indicating that it is the free fatty acid that influences the bacterial activity.
Abstract: Low concentrations of the long-chain fatty acids oleate and stearate inhibited all steps of the anaerobic thermophilic biogas process during digestion of cattle manure. The lag phase increased when the concentrations of oleate and stearate were 0.2 g/l and 0.5 g/l, respectively, and no growth was found at concentrations of 0.5 g/l for oleate and 1.0 g/l for stearate. The toxic effect of these acids was permanent as growth did not occur when inhibited cultures were diluted to a non-inhibitory concentration. No adaptation to the fatty acids toxicity was observed by pre-exposing the cultures to non-inhibitory concentrations and the inhibitory response was the same as for cultures not pre-exposed to the fatty acids. Oleate was less inhibitory when added as a neutral oil in the form of the glycerol ester. This indicates that it is the free fatty acid that influences the bacterial activity.
379 citations
TL;DR: It is concluded that permeation of the plasma membrane of the adipocyte by long-chain FAs at physiological concentrations is mediated by a protein transporter with distinct specificity requirements.
274 citations
TL;DR: The binding of six physiologically important long chain fatty acids to defatted human plasma albumin was measured in a calcium-free Krebs-Ringer phosphate buffer, pH 7.4, and results were inconclusive concerning whether premicellar association of unbound fatty acid occurs.
272 citations
TL;DR: In this paper, a model for the nucleation of microcellular foams in amorphous thermoplastic polymers was proposed and the polystyrene-zinc stearate system was chosen as the model system.
Abstract: Experiments were performed to validate the model for the nucleation of microcellular foams in amorphous thermoplastic polymers. The polystyrene-zinc stearate system was chosen as the model system. Other additives such as stearic acid and carbon black were also investigated. Molecular weight and orientation effects were studied. Nitrogen and carbon dioxide were used to produce the microcellular bubbles. Results show that amounts of soluble additives at levels just below their solubility limit and high gas saturation pressures yield the most acceptable foams—ones with a large number of uniform small bubbles. In this region, the bubble number is sensitive to both the gas saturation pressure and the concentration of solutes. Increasing the concentration of soluble additives above the solubility limit has little effect on bubble number and almost eliminates the dependence on saturation pressure. Molecular weight and orientation had no effect on the number of bubbles produced. Similarly, carbon black, which is insoluble in and which bonds well to polystyrene, produced no effect on bubble numbers. The agreement between theoretical predictions and experimental results is reasonably good.
258 citations