ABSTRACT
The excellent compatibility of polyol esters (POEs) with general fluids coolants such as CO(2) and non-chlorinated coolants (e.g. hydrofluorocarbons, HFCs) in terms of solubility, miscibility and chemical stability has fostered their use as lubricants by the refrigeration industry. The most widely used POEs bases consist of esters of polyalcohols - such as pentaerythritol, dipentaerythritol and neopentylglycol - with mixtures of carboxylic acids of 4-10 carbon atoms. Their thermophysical properties (viscosity mainly) are crucial with a view to producing efficient lubricants for specific applications. Usually, POE formulations, which usually contain several bases, are characterized in terms of global indices. In this work, we developed a methodology based on NIR spectroscopy for the characterization and analysis of lubricant formulations. The products, including lubricant bases and lubricant formulations, are characterized by reference to two spectral libraries that are used to identify as the starting lubricant bases as well as the lubricant formulations. It has been proposed to build libraries in cascade for the differentiation of lubricant formulations without and with low content in additives. Once the identification of the formulation is applied PLS multivariate models are used to determine the components of a lubricant formulation and its viscosity.
ABSTRACT
Omega 3 fatty acids have healthcare benefits, but their absorption characteristics are not well defined, particularly for strategies to improve their bioavailability. We performed a double blind study comparing the bioavailability of 20% eicosapentaenoic acid in 4.5 grams of: natural triglyceride, reconstituted triglyceride, enzymatically synthesized triglyceride, monoglyceride and diglyceride. Seven healthy volunteers were given the supplements on five occasions while repeated measurements of eicosapentaenoic acid were taken to calculate the area under the curve for the next 24 hours. There was a significant difference between the mean of calculated area under the curve of eicosapentaenoic acid from reconstituted triglyceride (30.2) and that of the enzymatically synthesized triglyceride (11.9) and monoglyceride (13.4), z=-2.36 and -2.19, respectively, p<0.05. In summary, eicosapentaenoic acid bioavailability of chemically reconstituted triglycerides was better than that obtained from enzymatically synthesized triglyceride and monoglyceride.