PubMed · 14217250
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R D MCKENNA. 1964-10-17. DRUGS FOR FUNCTIONAL CONSTIPATION.. https://pubmed.ncbi.nlm.nih.gov/14217250/
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Different scattering methods were used as tools to assess the size of droplets in highly diluted microemulsions. These were obtained after dilution of a self-emulsifying system made up of an oil, a surfactant and ethanol. Typical methods, often used in size and shape determination of particles, such as SAXS and USAXS suffer in the present case from a lack of electrondensity contrast. It becomes clear from our extensive use of dynamic light scattering that one should be careful in interpreting the latter data as well. Sample preparation and the subsequent handling of the samples during the experiments strongly affect reproducibility of the results. There is a need for well-defined protocols at the level of sample preparation and data handling. In the present research one uses extensively dynamic light scattering (DLS) in the back scattering mode and strengths and pitfalls, inherent to the backscattering technique, are discussed. It is crucial to be aware of droplet size distributions (monomodal/bimodal/multimodal) while reporting mean radii (Rh) as this radius is only relevant in the case of well-defined monomodal distributions. Moreover, one should asses the shape of the droplets prior to data interpretation, as usual in scattering methods, by an independent method. Anyway the shape of the time correlation functions of the scattered intensity should be reported or at least inspected as they provide information on the reproducibility of the experiments hence safegarding the value of the physical meaning of the final value of droplet size (Rh). Preferentially static light scattering (SLS) measurements should always support DLS experiments as the angular dependence is very sensitive to the presence of large particles.
Even though castor oil is inedible, it has long been an article of commerce. This is, in large measure, due to the versatility of the oil. This article discusses the extraction of castor oil and its refining methods and reviews the industrial applications of the oil. Since castor oil is not edible, it could be substituted in many industrial application areas where edible oils are used. An awareness of the various uses of the oil can be used to make a strong case for an increase in its production as a vital raw material for the chemical industries.
The transesterification of castor oil with ethanol in the presence of sodium ethoxide as catalyst is an exceptional option for the Brazilian biodiesel production, because the castor nut is quite available in the country. Chemically, its oil contains about 90% of ricinoleic acid that gives to the oil some beneficial characteristics such as its alcohol solubility at 30 degrees C. The transesterification variables studied in this work were reaction temperature, catalyst concentration and alcohol oil molar ratio. Through a star configuration experimental design with central points, this study shows that it is possible to achieve the same conversion of esters carrying out the transesterification reaction with a smaller alcohol quantity, and a new methodology was developed to obtain high purity biodiesel.