Effects of resistive switching in Au/FeO<Subscript>x</Subscript>/Pt structures

The dynamics of forming and resistive switching in Au/iron oxide/Pt structures based on magnetite (Fe₃O₄) is investigated. It has been revealed that these processes have an electrochemical nature and are accompanied by formation of low-resistance conductive filaments formed by inclusions of magnetite in the matrix of high-resistance maghemite (γ-Fe₂O₃). It has been found that the electric field stimulates reversible redox reactions in iron oxide. The direction and rate of these reactions are determined by the polarity and the amplitude of voltage pulses. The possibility of setting the resistance of the structure by changing the amplitude of the “record” voltage pulses opens prospects for the development of multilevel memory elements.     

Polypropylene composites obtained from self‐reinforced hybrid fiber system

The purpose of the study was to obtain a composite material with the self‐reinforced structure, which processing provide increased mechanical properties. The composites used in presented work were prepared from the two types of fiber mixtures, both were based on polypropylene fibers, the difference was in used cellulose or wood flour filler. Composites were prepared using the hot compaction method. The presented research describes the effect of the composite composition and processing conditions. The results include the static tension measurements, tensile impact tests and thermal analysis, including: DSC and DMTA. The structure has been studies using the SEM observations. Results of presented studies confirm the self‐reinforcing effect in obtained hybrid composites. It provides in the comparison to the standard wood polymer composites to the higher level of material reinforcement with lower amount of natural filler. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43283.     

Polythiophene nanoparticles in aqueous media

The article presents the data concerning the synthesis of polythiophene (PTh) nanoparticles in aqueous medium applying emulsion polymerization. The synthetic method was studied in variety of combinations of initiator and surfactant. It was found that application of potassium peroxydisulfate (KPS) as initiator and sodium dodecyl sulfate (SDS) as the surfactant gives the best product yields. The structure, morphology, and physicochemical properties have been analyzed showing that the resulting latex have conducting film forming properties. Resulting polymers were characterized via fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), thermogravimetry‐differential thermal analysis (TG‐DTA), differential scanning calorimetry (DSC), and electrochemical methods [e.g. current–voltage characteristics (I–V), activation energy of electric conductivity, and doping processes]. A mechanism of the polymerization reaction is also discussed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43495.     

A GENERALIZED BLOCK BOOTSTRAP FOR SEASONAL TIME SERIES

When time‐series data contain a periodic/seasonal component, the usual block bootstrap procedures are not directly applicable. We propose a modification of the block bootstrap – the generalized seasonal block bootstrap (GSBB) – and show its asymptotic consistency without undue restrictions on the relative size of the period and block size. Notably, it is exactly such restrictions that limit the applicability of other proposals of block bootstrap methods for time series with periodicities. The finite‐sample performance of the GSBB is also illustrated by means of a small simulation experiment.     

TIG brazing technology for zinc-coated sheet steel for bodywork

We propose a method for the assessment of the state of welded joints in terms of arc voltage signals and feed rate appraisal. The signals were recorded during laboratory tests. For the appraisal of the signals, we applied numerical parameters such as, for instance, kurtosis. On the basis of analysis results, we developed diagnostic rules which were written in the binary diagnostic matrix. The proposed method has been implemented in the form of software, the correctness of which has been verified on experimental data.     

Application of averaged instantaneous power spectrum for diagnostics of machinery operating under non-stationary operational conditions

Vibration analysis of machines operating under non-stationary operational conditions requires special attention. This refers to the necessity of use of order tracking algorithms together with additional advanced signal processing methods, especially when faults indicators of interest are located in resonance frequency ranges.     

Physico-chemical properties and antibacterial activity of modified egg white—lysozyme

Lysozyme (N-acetyl-muramyl-hydrolase E.C. 3.2.1.17) is a low-molecular enzyme (14,400 Da) found in body secretions, systemic fluids and tissues of humans and animals. Antibacterial activity of lysozyme monomer is limited first of all to Gram-positive bacteria, which is connected with the structure of the cell wall. This enzyme catalyzes hydrolysis of β-glycoside bonds (1–4), releasing N-acetylglucosamine and N-acetylmuramic acid. The spectrum of antibacterial activity of lysozyme may be extended thanks to modifications of the enzyme. The aim of the study was to assess antibacterial activity, hydrolytic activity and surface hydrophobicity of different forms of lysozyme. Chemical and thermo-chemical modification of lysozyme was performed, and the antibacterial action of lysozyme monomer and modified preparations were compared. It was found that in comparison with monomer and the control, all modified preparations exhibit effective action against Gram (−) bacteria Pseudomonas fluorescens. A particularly effective action was found in case of lysozyme subjected to thermo-chemical modification, which was characterized by the highest proportion of oligomeric forms and the highest hydrophobicity.     

The impact of liberalisation of the electricity market on the hard coal mining sector in Poland

The liberalisation of the electricity market changed the conditions of operation not only for the power industry, but also for related sectors. One of the particularly sensitive industries in Poland is coal mining, which is the result of coal-based structure of electricity generation. As it is more difficult, in the liberalised market, to burden consumers with all the costs, electricity producers are eager to transfer the risk of operation to the suppliers. That increases uncertainty about the future of the hard coal industry. The aim of this paper was to quantitatively estimate the impact that liberalisation of the electricity markets may have on the coal mining sector in Poland. First of all, the possible areas of that impact were identified. Then the model, which involved detailed relations in the impact areas identified, was developed and employed to evaluate the performance of the mining sector. The comparison of scenarios of a monopolistic electricity sector with a liberalised one enabled an estimation of the scale of the impact on the mining sector to be made. The results showed that liberalisation causes decreased coal consumption and decreased operating profits in coal companies. However, some savings in electricity costs are possible for coal producers.     

XPS studies of perovskites surface instability caused by Ar+ ion and electron bombardment and metal deposition

X-ray Photoelectron Spectroscopy (XPS) was used to study the influence of low energy Ar⁺ ion bombardment, electron bombardment and Pt deposition on the SrTiO₃ (STO) single crystal electronic structure. Atomic composition changes were found and attributed to chemical reconstruction of the STO surface. A clear correlation between the presence of conducting, low Ti oxidation states in valence band and core level changes was detected. A strong effect caused by electron irradiation was ascribed to the electroreduction process. The influence of lanthanum doping on surface instability of STO was also discussed. The La doped sample (STO: 3,75% La) was found to be modified upon Pt metal deposition to a higher degree than pure STO crystal.