Browsing by Author "Nikolova A."
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Item Erratum to Extraction of biologically active compounds from Propolis and concentration of extract by nanofiltration [J. Membr. Sci., (2010), 348, 124-130](2010-07-01) Tylkowski B.; Trusheva B.; Bankova V.; Giamberini M.; Peev G.; Nikolova A.Item Potential possibilities of a new method for yield stress determination(2016-01-01) Peev G.; Peshev D.; Nikolova A.One-D solution for the hydrodynamic characteristics of waveless film flow of an Ellis liquid on a horizontal rotating disk is obtained and considered for determination of the liquid yield stress. Several versions of the method based on the film thickness of the remaining liquid on the disk at a zero feed flow rate are proposed. Verification that such layer remains is provided. The limitations of the method advanced which refer to wave formation, film breakup, liquid adhesion and disk wetting are discussed in view of its application in rheometry.Item Rheological investigations of poly(hydroxybutyrate) and poly(ethylene oxide) solutions and their mixtures(2014-01-01) Nikolova A.; Schnabel R.Rheological investigations were carried out of poly (hydroxybutyrate) and poly (ethylene oxide) solutions in chloroform as well as of their mixtures in different ratios. It was established that all solutions (pure polymers and their mixtures) exhibit non-Newtonian (shear thinning) behaviour which is described by the Ostwald-de Waele model. The value of the activation energy for the solutions can be a measure for the influence of the temperature on their rheological behaviour.