Ulam type stability problems for alternative homomorphisms

We introduce an alternative homomorphism with respect to binary operations and investigate the Ulam type stability problem for such a mapping. The obtained results apply to Ulam type stability problems for several important functional equations.ArticleJOURNAL OF INEQUALITIES AND APPLICATIONS. 2014:228 (2014)journal articl

Badania czystości chemicznej biodegradowalnych włókien z PLA przeznaczonych na wyroby medyczne

The chemical purity of biodegradable poly(D,L-lactide) (PLA) fibres finished with various finishing agents was examined. Chemical purity parameters of aqueous extracts of the fibres were assessed, including turbidity, the content of sulphate and chloride ions, the content of water-dissolvable substances, the content of foaming agents, the content of heavy metal ions and pH. The content of organic solvent-leachable substances was also estimated according to the PN-EN ISO 10993-12:2009 standard. Tests under equal conditions were performed for PLA fibres spun without any spinfinish, PLA fibres with the spinfinish removed by extraction with organic solvents, and the raw material, PLA 6201D granulate. The certified fibre-grade polymer PLLA produced by Boehringer Ingelheim Pharma GmbH & Co KG (Germany) under the trade name Resomer L 207S served as the reference material and was analysed in the same way. In terms of chemical purity, PLA fibres finished with Estesol PF-790, pharmaceutical glycerol (glycerine), and PLA fibres after removal of the spinfinish were found to be suitable to use in hygiene and medical devices.Przeprowadzono badania czystości chemicznej biodegradowalnych włókien wytworzonych z poli(D,L-laktydu mlekowego) – PLA z naniesionymi w procesie przędzenia różnymi rodzajami preparacji. Przygotowane wyciągi wodne z włókien wytworzonych z PLA poddano ocenie w zakresie podstawowych parametrów czystości chemicznej: stopnia zmętnienia, zawartości jonów siarczanowych i chlorkowych, zawartości substancji rozpuszczalnych w wodzie, zawartości środków pianotwórczych, zawartości jonów metali ciężkich oraz odczyn pH wyciągów. Zawartość substancji wymywanych z włókien PLA rozpuszczalnikami organicznymi oznaczono wg PN-EN ISO 10993-12:2009. W tych samych warunkach zbadano czystość chemiczną włókien z PLA otrzymanych w procesie przędzenia bez naniesienia preparacji, włókien z PLA po usunięciu preparacji metodą ekstrakcji rozpuszczalnikami organicznymi oraz surowca do otrzymania włókien – granulatu PLA 6201D. Jako materiał odniesienia przyjęto certyfikowany polimer PLLA przeznaczony na wyroby medyczne, który poddano badaniom czystości chemicznej w tych samych warunkach. Stwierdzono, że pod kątem czystości chemicznej włókna z PLA z naniesionymi preparacjami: Estesol PF-790 i gliceryną farmaceutyczną, oraz włókna z PLA po usunięciu tych preparacji mogą znaleźć zastosowanie jako półfabrykaty do otrzymywania płaskich wyrobów higienicznych i/lub medycznych

Removal of Zinc Ions from Aqueous Solutions with the Use of Lignin and Biomass. Part II

In response to the trend toward sustainable management of by-products from the pulp and paper industry as well as plant waste, practical and economical methods are being developed to use them in a way that does not pose a threat to the environment. The main aim of the research was to study the possibility of using lignin and plant biomass as biosorbents for the removal of zinc ions from aqueous solutions. The secondary aim was to build an optimal multilayer system made of biosorbents selected during the research in order to obtain the highest sorption efficiency and to determine the best conditions of the sorption process. The effectiveness of zinc ion sorption was assessed using an appropriate combination of sorbents such as lignin, oat bran, rice husk, chitosan, pectin, sodium alginate, pine bark, coconut fiber and activated carbon, selected on the basis of literature data and the preliminary results of tests carried out using FTIR and AAS. The main component of the sorption system was lignin separated from black liquor. Results indicate that the best Zn sorption system was based on coconut fiber, lignin, and pine bark, for which the maximum sorption efficiency was 95%. The research also showed that the increase in the process temperature, the mass of biosorbents used and the alkaline pH are the factors that increase the efficiency of the sorption. It can be concluded that lignin and plant biomass can be used as ecological sorbents of zinc ions from water solutions. They are safe for the environment, produced from renewable sources, and are by-products or waste materials, which is part of the sustainable development and circular economy currently promoted in the EU