Kształtowanie granic niepodległej Polski w świetle dokumentów kartograficznych

Publikacja naukowa finansowana w ramach programu Ministra Edukacji i Nauki pod nazwą „Kształtowanie granic niepodległej Polski w świetle dokumentów kartograficznych” w latach 2018‒2023, numer projektu: 01SPN17003218, kwota finansowania 1 228 485 z

Convenient route to PHB macromonomers via anionically controlled moderate-temperature degradation of PHB

none5The degradation of poly(3-hydroxybutyrate)s in homo and heterogeneous mixtures with selected salts of organic and mineral acids was investigated. Nonvolatile degradation products, of processes conducted at moderate temperatures (150–170 C), were analyzed using 1H NMR. Analysis of results revealed a significant decrease in poly([R]-3-hydroxybutyrate) (PHB) thermal stability in the presence of acetic acid and carbonic acid salts of alkali metals (Cs, K, Li) as well as a less substantial effect with respect to bivalent metal (Ca, Mg, Zn) salts. This significant decrease in PHB thermal stability in the presence of salts of weak Bronsted-Lowry acids can be explained in terms of an anionic degradation reaction proceeding via an E1cB mechanism. Furthermore, continuous poly(3-hydroxybutyrate) controlled degradation was developed by a moderate-temperature process using carbonic acid salts as ‘‘initiators’’ of anionic degradation. Foamed PHB macromonomers, bearing one crotonate terminal group, were obtainable via a reactive extrusion processnoneM. Kawalec; M. Sobota; M. Scandola; M. Kowalczuk; P. KurcokM. Kawalec; M. Sobota; M. Scandola; M. Kowalczuk; P. Kurco

Zirconium (IV) Acetylacetonate: Ring-Opening Initiator Mediating One-Step Synthesis of Biodegradable Polyacids

Biodegradable polyacid is obtained in one-step ring-opening polymerization (ROP) of carboxylic-acid-functionalized six-membered cyclic carbonate mediated with zirconium (IV) acetylacetonate. Exemplary copolymers with L,L-lactide are described as well. Moreover, zirconium (IV) acetylacetonate is found to be active catalyst of trimethylene carbonate (TMC) ROP in presence of carboxylic acid yielding PTMC end-capped with the acid derivative. Polymerization mechanism is hypothesized demonstrating possibilities of the method in work-saving polycation synthesis and one-step method of conjugate synthesis of well-known biocompatible polyesters and polycarbonates

Morpholine-functionalized polycarbonate hydrogels for heavy metal ion sequestration

A new six-membered carbonate functionalized with 2-(morpholin-4-yl)ethyl was synthesized and copolymerized with a poly(ethylene oxide)-based cross-linker in a controlled, organocatalyzed ring-opening polymerization process. Well-defined functionalized aliphatic polycarbonate-based hydrogels were obtained with gel fractions reaching 99%. Moreover, the gels that contained 2-(morpholin-4-yl)ethyl groups revealed stimuli-responsive properties towards pH. In the meantime, swelling properties of the hydrogels were found to be reproducible and good stability was observed in the pH range of 4–7.2, while a relatively rapid degradation occurred in more basic solution (pH = 10). ICP MS measurements of aqueous lead(II) nitrate solutions revealed that the functionalized material possessed properties to withdraw and retain lead ions from aqueous solution

Applications of the continuously rotating detonation to combustion engines at the Łukasiewicz - Institute of Aviation

In the paper short information about advantages of introduction of detonation combustion to propulsion systems is briefly discussed and then research conducted at the Łukasiewicz-Institute of Aviation on development of the rotating detonation engines (RDE) is presented. Special attention is focused on continuously rotating detonation (CRD), since it offers significant advantages over pulsed detonation (PD). Basic aspects of initiation and stability of the CRD are discussed. Examples of applications of the CRD to gas turbine and rocket engines are presented and a combine cycle engine utilizing CRD are also evaluated. The world's first rocket flight powered by liquid propellant detonation engine is also described

Synthesis of Polyacids by Copolymerization of l-Lactide with MTC-COOH Using Zn[(acac)(L)H2O] Complex as an Initiator

This work presents the results of research on the preparation of bioresorbable functional polyestercarbonates containing side carboxyl groups. These copolymers were synthesized in two ways: the classic two-step process involving the copolymerization of l-lactide and a cyclic carbonate containing a blocked side carboxylate group in the form of a benzyl ester (MTC-Bz) and its subsequent deprotection, and a new way involving the one-step copolymerization of l-lactide with this same carbonate, but containing an unprotected carboxyl group (MTC-COOH). Both reactions were carried out under identical conditions in the melt, using a specially selected zinc chelate complex, with Zn[(acac)(L)H2O] (where: L—N-(pyridin-4-ylmethylene) phenylalaninate ligand) as an initiator. The differences in the kinetics of both reactions and their courses were pictured. The reactivity of the MTC-COOH monomer without a blocking group in the studied co-polymerization was much higher, even slightly higher than l-lactide, which allowed the practically complete conversion of the comonomers in a much shorter time. The basic final properties of the obtained copolymers and the microstructures of their chains were determined. The single-step synthesis of biodegradable polyacids was much simpler. Contrary to the conventional method, this made it possible to obtain copolymers containing all carbonate units with carboxyl groups, without even traces of the heavy metals used in the deprotection of the carboxyl groups, the presence of which is known to be very difficult to completely remove from the copolymers obtained in the two-step process

Power sources involving ~ 300W PEMFC fuel cell stacks cooled by different media

Two constructions of ~300W PEMFC stacks, cooled by different media, were analysed. An open-cathode ~300W PEMFC stack cooled by air (Horizon, Singapore) and a PEMFC F-42 stack cooled by a liquid medium (Schunk, Germany) were chosen for all of the investigations described in this paper. The potential for the design and construction of power sources involving fuel cells, as well as of a hybrid system (fuel cell-lithium battery) for mobile and stationary applications, is presented and discussed. The impact of certain experimental parameters on PEMFC stack performance is analysed and discussed

Power sources involving ~ 300W PEMFC fuel cell stacks cooled by different media

Two constructions of ~300W PEMFC stacks, cooled by different media, were analysed. An open-cathode ~300W PEMFC stack cooled by air (Horizon, Singapore) and a PEMFC F-42 stack cooled by a liquid medium (Schunk, Germany) were chosen for all of the investigations described in this paper. The potential for the design and construction of power sources involving fuel cells, as well as of a hybrid system (fuel cell-lithium battery) for mobile and stationary applications, is presented and discussed. The impact of certain experimental parameters on PEMFC stack performance is analysed and discussed