Noise Spectrum as a Source of Information in Gas Sensors Based on Liquid-Phase Exfoliated Graphene

Surfaces of adsorption-based gas sensors are often heterogeneous, with adsorption sites that differ in their affinities for gas particle binding. Knowing adsorption/desorption energies, surface densities and the relative abundance of sites of different types is important, because these parameters impact sensor sensitivity and selectivity, and are relevant for revealing the response-generating mechanisms. We show that the analysis of the noise of adsorption-based sensors can be used to study gas adsorption on heterogeneous sensing surfaces, which is applicable to industrially important liquid-phase exfoliated (LPE) graphene. Our results for CO2 adsorption on an LPE graphene surface, with different types of adsorption sites on graphene flake edges and basal planes, show that the noise spectrum data can be used to characterize such surfaces in terms of parameters that determine the sensing properties of the adsorbing material. Notably, the spectrum characteristic frequencies are an unambiguous indicator of the relative abundance of different types of adsorption sites on the sensing surface and their surface densities. We also demonstrate that spectrum features indicate the fraction of the binding sites that are already occupied by another gas species. The presented study can be applied to the design and production of graphene and other sensing surfaces with an optimal sensing performance

Chokeberry juice affects membrane lipid status and cellular antioxidant enzymes in healthy women with aerobic training activity

The present study examined the effects of aerobic training alone or combined with chokeberry juice on membrane lipid status and activities of antioxidant enzymes in non-athlete women. Participants were randomly assigned into the training group performing aerobic training three times per week; the chokeberry-training group followed the same training regime and additionally consumed 100 ml of chokeberry juice per day and the control group neither trained nor consumed the juice. Blood samples were collected at baseline and the end of the eight-week-long intervention. Membrane fatty acids’ composition was analyzed by gas-liquid chromatography, while the activities of antioxidant enzymes were measured by spectrophotometry. As a result, the n-3 fatty acids’ content was significantly higher in the chokeberry-training (median (interquartile range) of 5.96 (1.65) %) compared with the control group (5.12 (0.87) %), while saturated fatty acids’ content was lower in the chokeberry-training (40.14±1.19 %) than in the training group (42.59±2.29 %). We detected significantly higher activity of superoxide dismutase in the training (2224 (2170) U/gHb) compared with the chokeberry-training (1252 (734) U/gHb) and control group (1397 (475) U/gHb). Our study indicates that supplementation with chokeberry juice may induce favorable changes in cell fatty acid composition and antioxidant response in women performing aerobic training

Improvement of the corrosion characteristics of 1.4713 ferritic steel in 0.1 M sulfuric acid by heat treatment and Al2O3-TiO2 coating

This study addresses the influence of heat treatment and alumina coating on the corrosion of EN 1.4713 steel in 0.1 mol dm(-3) sulfuric acid. The corrosion characteristics of three different samples are examined using the open circuit potential measurements, Tafel extrapolation, linear polarization resistance, weight-loss method, and electrochemical impedance spectroscopy. The results showed that the application of the weight-loss method yielded similar values to the electrochemical method in the first 24 h. A decrease in corrosion rate, in a similar manner, was observed for all three samples. The largest deacceleration was obtained for the alumina/titania-coated sample. It was obtained that the heat treatment significantly increased the corrosion resistance, but only in the first 24 h. The alumina/titania coating decreases the corrosion rate by approximately 30 times at the beginning of the corrosion exposure and by nearly 300 times after 240 h. This coating could have a significant influence on construction design, which uses ferritic stainless steel as the material

Effect of alumina coatings on corrosion behavior of X10CrAlSi7 steel in sulfuric acid

The results of experimental studies of the effect of the plasma sprayed alumina coating on the improved corrosion resistance of the heat-resistant ferritic stainless steel (W.Nr. 1.4713, EN X10CrAlSi7) in the sulfuric acid are presented in this research. In this investigation, the plasma spray process was employed on the substrate of ferritic stainless steel with deposition of Al2O3 ceramic coatings with Ni5%Al as a bond layer. Two different coating thicknesses of 0.3 mm and 0.5 mm were tested. The investigation was performed by electrochemical characterization and weight loss method. Electrochemical characterization of corrosion behavior of steel with and without ceramic coating was performed by: the open circuit potential measurement (OCP), the linear polarization resistance (LRP) method, and the Tafel extrapolation method. All electrochemical measurements were performed in the sulfuric acid with a concentration of 0.25 mol/dm3 (pH 1.00). Weight loss method was performed with a duration of 240 h in the 38 wt.% sulfuric acid. Corrosion current densities obtained by electrochemical methods with the coatings were between 3 and 4 % of the values of the samples without coatings. Nearly the same results were obtained with the weight loss method. In both cases, these values are similar to the porosity of the coatings

Mapping the potential for decentralized energy generation based on RES in Western Balkans

Although the countries of the Western Balkans are mostly electrified, there are still regions which do not have access to the electricity network or where the network capacity is insufficient. For the most part such areas are under special care of the state (i. e. underdeveloped, devastated by war, depopulated), on islands or in mountainous regions. Since the decentralized energy generation covers a broad range of technologies, including many renewable energy technologies that provide small-scale power at sites close to the users, such concept could be of interest for these locations. This paper identifies the areas in Western Balkans where such systems could be applied. Consideration is given to geographical locations as well as possible applications. Wind, hydro, solar photovoltaic, and biomass conversion systems were taken into consideration. Since the renewable energy sources data for Western Balkans region are rather scarce, the intention was to give a survey of the present situation and an estimate of future potential for decentralized energy generation based on renewable energy sources. The decentralized energy generation based on renewable energy sources in Western Balkans will find its niche easier for the users that will produce electricity for their own needs and for the users located in remote rural areas (off-grid applications)

Mapping the potential for decentralized energy generation based on RES in Western Balkans

Although the countries of the Western Balkans are mostly electrified, there are still regions which do not have access to the electricity network or where the network capacity is insufficient. For the most part such areas are under special care of the state (i.e. underdeveloped, devastated by war, depopulated), on islands or in mountainous regions. Since the decentralized energy generation covers a broad range of technologies, including many renewable energy technologies that provide small-scale power at sites close to the users, such concept could be of interest for these locations. This paper identfies the areas in Western Balkans where such systems could be applied Consideration is given to geographical locations as well as possible applications. Wind hydro, solar photovoltaic, and biomass conversion systems were taken into consideration. Since the renewable energy sources data for Western Balkans region are rather scarce, the intention was to give a survey of the present situation and an estimate of future polential for decentralized energy generation based on renewable energy sources. The decentralized energy generation based on renewable energy sources in Western Balkans will find its niche easier for the users that will produce electricity for their own needs and for the users located in remote rural areas (off-grid applications)