Thermodynamic aspects of power generation in imperfect fuel cells: part II

This research continues the thermodynamic analysis of steady-state solid oxide fuel cells initiated in Sieniutycz (Sieniutycz, S., 2010, Thermodynamic aspects of power generation in imperfect fuel cells: part I. International Journal of Ambient Energy, 31 (4), 195–202). This analysis focuses on the effect of incomplete conversions in chemical reactions. A general approach is developed that attributes lowering of the cell voltage below its reversible value to polarisations and imperfect chemical conversions. Relevant model, appropriate for systems with complete conversions, is extended to imperfect cases. The performance curves of a fuel cell and the effect of typical design and operating parameters on the cell behaviour are analysed. A general result is obtained for power limits of fuel cells propelled by linear transport phenomena.     

Extraction of phenolic compounds from sour cherry pomace with supercritical carbon dioxide: Impact of process parameters on the composition and antioxidant properties of extracts

Sour cherry (Prunus cerasus) is rich in biologically active phenolic compounds. These compounds are concentrated in fruit skin and most of them remain in the leftovers during the production of juice. Supercritical carbon dioxide extraction was used to separate phenolic compounds from sour cherry pomace. The effects of temperature, pressure and the addition of ethanol on anthocyanin and the total phenolic content and radical scavenging activity of the extracts were investigated. The best results were acquired for 35°C, 10 MPa and 80% ethanol addition. A strong correlation was found between the phenolic content and other features of the extracts.     

The influence of electron beam irradiation,plastic deformation,and re‐irradiation on crystallinity degree,mechanical and sclerometric properties of GUR 1050 used for arthroplasty

The article describes the influence of an electron beam irradiation (I), plastic deformation (D), and re‐irradiation (R) on the properties of ultrahigh molecular weight polyethylene (GUR 1050). It was found that the modification through irradiation entailed a gradual increase in the degree of crystallinity (after irradiation–I). After plastic deformation and re‐irradiation (IDR) the degree of crystallinity decreases which had a direct influence on the mechanical properties. The polymer irradiation only (technique I) resulted in an increase in the maximum stress as compared with the material in the initial state. The application of deformation and re‐irradiation (technique IDR) allowed increasing the deformation resistance by more than 40%. Moreover, the irradiation with an electron beam resulted in the increase in hardness (H) and Young's modulus (E) proportionally to the applied irradiation dose and in the reduction of total indentation work (W_tot) and its components. After deformation and re‐irradiation the polyethylene hardness went down. The application of technique (I) caused an improvement to the material abrasion resistance (reduction of parameter PD–working scratch depth) with the increasing irradiation dose. The introduction of deformation and re‐irradiation did not have a material impact on parameter (PD) increasing at the same time elastic properties of UHMWPE (increase in parameter NPS–elastic recovery). Modification IDR has changed the wear mechanism (β) toward ploughing and has increased the abrasion‐resistance index (W_β) and also significantly reduced the coefficient of friction (μ) of GUR 1050. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43683.     

Traumatic Acid Reduces Oxidative Stress and Enhances Collagen Biosynthesis in Cultured Human Skin Fibroblasts

Traumatic acid (TA) is a plant hormone (cytokinin) that in terms of chemical structure belongs to the group of fatty acids derivatives. It was isolated from Phaseolus vulgaris. TA activity and its influence on human cells and organism has not previously been the subject of research. The aim of this study was to examine the effects of TA on collagen content and basic oxidative stress parameters, such as antioxidative enzyme activity, reduced glutathione, thiol group content, and lipid peroxidation in physiological conditions. The results show a stimulatory effect of TA on tested parameters. TA caused a decrease in membrane phospholipid peroxidation and exhibited protective properties against ROS production. It also increases protein and collagen biosynthesis and its secretion into the culture medium. The present findings reveal that TA exhibits multiple and complex activity in fibroblast cells in vitro. TA, with its activity similar to unsaturated fatty acids, shows antioxidant and stimulatory effects on collagen biosynthesis. It is a potentially powerful agent with applications in the treatment of many skin diseases connected with oxidative stress and collagen biosynthesis disorders.     

Friction coefficient and wear resistance of a modified polypropylene impregnated with different oils

The aim of the study was to determine the changes in the sliding friction coefficient and wear mechanism of PP impregnated by oils with respect to the unmodified PP under dry sliding conditions. The study showed that the impregnation of the PP clearly influenced the wear rate of PP and its friction coefficient. During the test, the wear behavior of the unmodified and impregnated polypropylenes was investigated using ASTM G77-98 standard wear test equipment in which the specimens were worn by counter sample made by steel 100Cr6. The recording program of the test system enabled the visualization and registration of the following parameters: specimen rotation and load value, linear wear of specimen, friction coefficient, and temperature of specimen and environment. The wear of the specimens was evaluated by weight loss and their wear mechanisms were investigated using scanning electron microscopy. The predominant wear mechanism between a polymer and steel was adhesion. However, at the high sliding velocity, when a higher temperature was generated, the predominant mechanism of wear was thermal wear. Impregnation of PPs moved the thermal wear into the higher sliding velocity values and caused better resistance of the PPs to melting and plastic flow. The most important finding of this investigation was that impregnation of PPs improved their tribological properties at a low value of load represented by the sliding velocity.     

The Use of Reverse Osmosis in the Removal of PAHs from Municipal Landfill Leachate

Polycyclic aromatic hydrocarbons (PAHs) are relatively well-known organic pollutants and due to their carcinogenic and mutagenic properties their presence in the environment still attracts a lot of attention.

According to literature reports and own research, PAHs presence in wastewaters is common. It was confirmed that PAHs are the components of municipal landfill leachate. Membrane techniques are one of the most interesting ways of removing PAHs from leachate.

The purpose of this article is to monitor PAHs concentration changes during the membrane (reverse osmosis - RO) leachate treatment processes. In the first stage of testing leachates were filtrated on the sand bed (pre-filtration). After the pre-filtration they were directed to the membrane module for the main filtration.

Sixteen PAHs listed by EPA were analyzed. The results with information on PAHs concentration in leachate samples were presented using HPLC with fluorescence detection (FLD). The changes in PAHs concentration were determined in leachate samples before and after pre-filtration as well as after RO. The decrease of PAHs concentration in the samples was observed after these processes. The total concentration of 16 PAHs in raw municipal landfill leachates amounted to 23.64–26.95 μg/L. The research confirmed the high efficiency in removal of PAHs while using a reverse osmosis (59–72%). Including the pre-filtration, the overall level of removed PAHs reached 81–86%. The average PAHs concentration after pre-filtration and RO was in the 4.46–4.99 μg/L range. The municipal landfill leachate with a high concentration of PAHs should be cleaned before it is discharged into the environment.     

Synthesis,spectroscopic characterisation,and potential application of dyes containing a carbostyril skeleton as sensors for thiols

Several dyes based on a carbostyril skeleton were synthesised and characterised using proton nuclear magnetic resonance spectroscopy and electron ionisation mass spectrometry. Their basic spectroscopic properties, such as absorption and emission spectra, were also measured. The behaviour of the obtained dyes in the absence and presence of thiol amino acids and other compounds under various conditions were studied. These dyes contain various moieties in the structure, acting as Michael acceptors. Results show that the studied compounds have the potential to act as colorimetric sensors for thiols, but the benzothioazolium dyes are less effective than dicyanoethylene derivatives.     

Microstructure and properties of friction stir welded aluminium alloys

Aluminium alloy 7136 belongs to the Al–Zn–Mg–Cu group of aluminium alloys strengthened by precipitation. These alloys offer very good properties, i.e. high strength combined with good corrosion resistance, which makes them suitable for aerospace applications. The limited range of applications of these alloys is due to problems associated with their welding. The Al–Zn–Mg–Cu alloys are classified as non-weldable. The aim of this study was to determine the quality and properties of friction stir welded (FSW) joints of alloy 7136-T76. This article presents the results of a detailed study into the microstructure and mechanical properties of FSW welds. The paper demonstrates that the FSW method is suitable for joining Al–Zn–Mg–Cu alloys. The FSW joints are of good quality and high mechanical properties. Tests of joints created at various tool rotation speeds have shown that joints of suitable quality, in terms of microstructure and properties, can be obtained for a relatively wide range of process parameters. The tool rotation speeds applied during the welding process did not have a significant influence on the quality of the welds.     

Microstructure study of poly(isobutyl acrylate) and poly(<Emphasis Type="Italic">sec</Emphasis>-butyl acrylate) by incremental analysis of <Superscript>13</Superscript>C NMR spectra

Microstructure of poly(isobutyl acrylate) (PiBuA) and poly(sec-butyl acrylate) (PsBuA), prepared by free radical and anionic polymerization, was investigated by ¹³C NMR spectroscopy. The carbonyl signal in the 100 MHz ¹³C NMR spectra of both homopolymers provided sufficient resolution to perform detailed analysis of distribution of configurational sequences at the pentad/heptad level. Application of Bernoulli and first order Markov statistics to determine probabilities of configurational sequences and incremental calculation to estimate chemical shifts of the individual sequences allowed for positive simulation of carbonyl signals.