Effect of redispersible polymer powder on setting time of thin-bed mortars

The aim of work is to describe and to complement the existing knowledge on the effect of redispersible polymer powder on the setting time of cement mortar as measured by means of ultrasonic apparatus. The mortars were simple mixtures of filler in the form of quartz sand, Portland cement CEM I 42.5 R as binder and methyl hydroxyethyl cellulose. The mortar additives were two commercially available redispersible polymer powders in an amount of 0-5% of total weight. The chosen polymers had different chemical structure: styrene-acrylic copolymer (SA), vinyl acetate-ethylene copolymer (ET), and minimum film forming temperature (MFFT). The amount of water was constant and equal to 20% of the total weight of the mortar. Conclusions: - even the small amount of redispersible polymer powder added to the cement mortar has a significant influence on mortar’s initial and final setting time and this effect strongly depends on the percentage of the additive, - the chemical structure of the studied redispersible polymer powders did not influence the behaviour of the whole chemical system, - the further studies on technical properties, such as mechanical strength and permeability are planned in order to find more information on the structure of hardened mortar

Impact resistance of external thermal insulation systems

In the paper the results of an experimental program intended to determine factors influencing the impact resistance of the External Thermal Insulation Composite Systems (ETICS) were presented. For the research the systems based on polystyrene have been chosen. The insulation material was faced with a rendering consisting of base coat reinforced with standard or armored glass fibre mesh and silicone or silicone-silicate binders as finishing coats. The influence of various renderings components was evaluated with respect to resistance to hard body impact and resistance to hail. The test results were discussed in the context of the possible impact level on ETICS in use

Impact resistance of external thermal insulation systems

In the paper the results of an experimental program intended to determine factors influencing the impact resistance of the External Thermal Insulation Composite Systems (ETICS) were presented. For the research the systems based on polystyrene have been chosen. The insulation material was faced with a rendering consisting of base coat reinforced with standard or armored glass fibre mesh and silicone or silicone-silicate binders as finishing coats. The influence of various renderings components was evaluated with respect to resistance to hard body impact and resistance to hail. The test results were discussed in the context of the possible impact level on ETICS in use

Characterization of fluorescein-based monoboronate probe and its application to the detection of peroxynitrite in endothelial cells treated with doxorubicin

Boronate probes have emerged recently as a versatile tool for the detection of reactive oxygen and nitrogen species. Here, we present the characterization of a fluorescein-based monoboronate probe, a 4-(pinacol boronate)benzyl derivative of fluorescein methyl ester (FBBE), that proved to be useful to detect peroxynitrite in cell culture experiments. The reactivity of FBBE toward peroxynitrite as well hypochlorite, hydrogen peroxide, and tyrosyl hydroperoxide was determined. Second-order rate constants of the reactions of FBBE with peroxynitrite, HOCl, and H2O2 at pH 7.4 were equal to (2.8 ± 0.2) × 105 M-1 s-1, (8.6 ± 0.5) × 103 M-1 s-1, and (0.96 ± 0.03) M-1 s-1, respectively. The presence of glutathione completely blocked the oxidation of the probe by HOCl and significantly inhibited its oxidation by H2O2 and tyrosyl hydroperoxide but not by peroxynitrite. The oxidative conversion of the probe was also studied in the systems generating singlet oxygen, superoxide radical anion, and nitric oxide in the presence and absence of glutathione. Spectroscopic characterization of FBBE and its oxidation product has been also performed. The differences in the reactivity pattern were supported by DFT quantum mechanical calculations. Finally, the FBBE probe was used to study the oxidative stress in endothelial cells (Ea.hy926) incubated with doxorubicin, a quinone anthracycline antibiotic. In endothelial cells pretreated with doxorubicin, FBBE was oxidized, and this effect was reversed by PEG-SOD and L-NAME but not by catalase

W poszukiwaniu Piastów

The origin of the Piast dynasty is a matter of lively discussions and disputes. At least a few controversial hypotheses exist, but their credibility is difficult to assess due to the scarcity of written as well as material sources, especially from the time of Polish state formation. Life sciences, however, can support history and archeology. Application of genetic tests, used earlier mainly in forensic laboratories, enabled identification of the remains of King Richard III, the Romanov dynasty members and Nicolaus Copernicus. Contemporary DNA studies, based on next generation DNA sequencing, outreach the narrow area of known markers such as mitochondrial DNA (mtDNA) and selected regions of Y chromosome. Although ancient DNA (aDNA), extracted from remains, is usually highly degraded and contaminated with genetic material of microorganisms, there are methods which allow for the analysis of such material and retrieval of information about origin, kinship and some phenotypic features of an individual. Genetic studies of the Piast dynasty, a subject of our research project, have to deal with numerous difficulties. In or der to gain access to bone samples, we need to meet a number of formal requirements. Moreover, despite the existence of available abundant documentation on the Piast burials, the actual situation is not always consistent with the written sources. Our first experiences show how difficult it is to localize the remains, identify them and extract DNA of sufficient quality.The origin of the Piast dynasty is a matter of lively discussions and disputes. At least a few controversial hypotheses exist, but their credibility is difficult to assess due to the scarcity of written as well as material sources, especially from the time of Polish state formation. Life sciences, however, can support history and archeology. Application of genetic tests, used earlier mainly in forensic laboratories, enabled identification of the remains of King Richard III, the Romanov dynasty members and Nicolaus Copernicus. Contemporary DNA studies, based on next generation DNA sequencing, outreach the narrow area of known markers such as mitochondrial DNA (mtDNA) and selected regions of Y chromosome. Although ancient DNA (aDNA), extracted from remains, is usually highly degraded and contaminated with genetic material of microorganisms, there are methods which allow for the analysis of such material and retrieval of information about origin, kinship and some phenotypic features of an individual. Genetic studies of the Piast dynasty, a subject of our research project, have to deal with numerous difficulties. In or der to gain access to bone samples, we need to meet a number of formal requirements. Moreover, despite the existence of available abundant documentation on the Piast burials, the actual situation is not always consistent with the written sources. Our first experiences show how difficult it is to localize the remains, identify them and extract DNA of sufficient quality