PubMed · 13284804
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J STEJSKAL. 1955. Perfume softened.. https://pubmed.ncbi.nlm.nih.gov/13284804/
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Large number of washable (o/w type) creams were prepared for rheological investigation. The rheological functions known from the literature were determined in our studies. Rheological constants were determined by measurements and calculations. From these, we selected those ones which were applicable to characterize the energy status of the coherent structure and which gave the most information for practical work, elaboration of composition and evaluation of stability. These functions and parameters are the following: flow curves, viscosity vs shear time and viscosity vs temperature functions, Bingham-type yield value, plastic viscosity, structure breakdown rate constant, activation energy.
The present study dealt with the investigation of the physical characteristics of 18 polyethylene glycol ointment bases with the aim of finding out their suitability for use in tropical and subtropical climates. Different ratios of low and high molecular weight polyethylene glycols were helpful for preparation of these ointment bases. The investigated physical characteristics included the drop point, the congealing range and the spreadability properties of bases. The drop point was determined by the Ubbelohde apparatus, the congealing range by the double-walled Zhuckov flask, penetrability by penetrometer, and spreadability by the parallel plate extensometer. The results of these physical parameters indicated that PEG 400:PEG 4000 blend gave very good bases for use in tropical and subtropical areas. Furthermore, it was observed that, the type and the amount of PEG used would affect greatly the drop point, congealing range and consistency of the prepared bases. Results obtained with PEG 2000 and PEG 6000 bases showed less variability with respect to molecular weight and solid content.
The biological activity of a series of 10 silver sulfanilamides is studied in relation to the physical parameters pK alpha, log K, and the aqueous solubility. None of the parameters demonstrate a simple relationship with the activity. A discussion of the significance of log K and the solubility in relation to the activity is given.