Anthropogenic pollution leads to increased concentrations of metals in the freshwater and macrophyte. Aquatic plants substantially contribute to the structure, function as well as and service provision of aquatic ecosystems. Our microcosm experiments were to test the possibility of the physiological response of Hydrocharis morsus-ranae to metal (Cd, Pb, Cu, Zn, Mn, Fe at three level of concentration) contaminated waters. Biomass was analysed at the beginning and at the end of the experiment. At the same time contents of photosynthetic pigments in leaves were estimated spectrophotometrically. We found that this macrophyte had the ability to grow in contaminated waters, but the effects of high concentration of isolated metals in water will indicate changes consisting in the disappearance of a significant part of biological populations were which manifested in alteration of the content of photosynthetic pigments as well as this plant’s growth. We show that generally stress of Zn and Cu influenced the drop of dry biomass which was connected with a positive correlation between the amount of dry biomass and the content of chlorophyll a and carotenoids, or only carotenoids, respectively. The highest stress of Pb and Fe (third concentrations of these metals) also influenced the drop of biomass. We concluded that none of Cd concentrations were toxic to this plant, but the effect of Mn stress was not unequivocal. Moreover, plant growth was stimulated by low Fe concentrations (first concentration) demonstrating the hormesis effect. When plants were exposed to this metal, there was no evidence of damage to the photosynthetic processes.

Elaborating composites containing waste materials requires study of basic mechanical properties and assessment of their structure quality. The subject of investigation was PPC concrete where aggregate was substituted with PET remaining after beverages bottles grinding. Substitution was done up to 25% (by volume). Waste material was fractioned and applied in various granulations. The main goal was to indicate the influence of such modification on the composite mechanical properties and to examine composite structure quality at macro level. Since PET and quartz differ greatly in density, to perform such examination it was possible to apply the nondestructive ultrasonic method, one of the most common NDT techniques used in material science and industry. The paper presents the effects of substitution of quartz with PET on ultrasonic wave propagation in PCC. The ultrasonic test results (measurements of wave velocity) compared with results of destructive tests (flexural and compressive strength) showed great correlation.

The paper presents the probabilistic model of fibrillation currents containing two components with different frequencies. An analysis was conducted of the threat of ventricular fibrillation which occurs in consequence of the electric shock with the highest permissible contact shocking voltage of the network frequency (50 Hz), taking into account the threat caused by the second component of the voltage which has the frequency higher than the network frequency. The sample results of calculations apply to the probability of the ventricular fibrillation in case of a shock caused by the highest permissible contact shocking voltage, for the defined time of shock duration, without and with the participation of an additional voltage component with higher frequency. The formula has been presented for the calculation of the highest permissible contact shock voltages with taking into account the voltage component of the frequency higher than the network frequency. The results of calculations indicate that a considerable reduction of the highest permissible contact shock voltage is necessary in order to compensate for a growth of the ventricular fibrillation threat caused by the presence of an additional component with the frequency other the network frequency. This applies in particular to the long shock duration times and low frequencies (up to 500 Hz) of an additional component of the shocking voltage.

Measurements of dynamic surface tension were carried out in aqueous systems (water or 0.1 mM Triton X-100) comprising nanoparticles formed from chemically modified polyaldehyde dextran (PAD). The nanostructures, considered as potential drug carriers in aerosol therapy, were obtained from biocompatible polysaccharides by successive oxidation and reactive coiling in an aqueous solution. The dynamic surface tension of the samples was determined by the maximum bubble pressure (MBP) method and by the axisymmetric drop shape analysis (ADSA). Experiments with harmonic area perturbations were also carried out in order to determine surface dilatational viscoelasticity. PAD showed a remarkable surface activity. Ward-Tordai equation was used to determine the equilibrium surface tension and diffusion coefficient of PAD nanoparticles (D = 2.3×10-6 m2/s). In a mixture with Triton X-100, PAD particles showed co-adsorption and synergic effect in surface tension reduction at short times (below 10 s). Tested nanoparticles had impact on surface rheology in a mixed system with nonionic surfactant, suggesting their possible interactions with the lung surfactant system after inhalation. This preliminary investigation sets the methodological approach for further research related to the influence of inhaled PAD nanoparticles on the lung surfactant and mass transfer processes in the respiratory system.

This paper reviews research at the Institute of Materials Science and Engineering, Poznań University of Technology, on the synthesis of nanocrystalline hydride electrode materials. Nanocrystalline materials have been synthesized by mechanical alloying (MA) followed by annealing. Examples of the mate2-, LaNi5 and Mg2Ni-type phases. Details on the process used and the enhancement of properties due to the nanoscale structures are presented. The synthesized alloys were used as negative electrode materials for Ni-MH battery. The properties of hydrogen host materials can be modi?ed substantially by alloying to obtain the desired storage characteristics. For example, it was found that the respective replacement of Fe in TiFe by Ni and/or by Cr, Co, Mo improved not only the discharge capacity but also the cycle life of these electrodes. The hydrogen storage properties of nanocrystalline ZrV2- and LaNi5-type powders prepared by mechanical alloying and annealing show no big di?erence with those of melt casting (polycrystalline) alloys. On the other hand, a partial substitution of Mg by Mn orAl in Mg2Ni alloy leads to an increase in discharge capacity, at room temperature. Furthermore, the e?ect of the nickel and graphite coating on the structure of some nanocrystalline alloys and the electrodes characteristics were investigated. In the case of Mg2Ni-type alloy mechanical coating with graphite e?ectively reduced the degradation rate of the studied electrode materials. The combination of a nanocrystalline TiFe-, ZrV2- and LaNi5-type hydride electrodes and a nickel positive electrode to form a Ni-MH battery, has been successful.