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Abstract  

La0.8Cu0.2MnO3 and La0.8Sr0.2MnO3 perovskite catalysts were prepared by the co-precipitation method. The resistance of these catalysts to sulfur poisoning was tested via catalytic combustion of toluene. The results show that the perovskite catalysts were poisoned in the presence of SO2. In the presence of dodecyl mercaptan (C12H25SH), La0.8Sr0.2MnO3 exhibits better resistance to sulfur poisoning than La0.8Cu0.2MnO3. It was determined that the SO2 deactivation is due to the formation of CuSO4 on the catalyst surface.

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Nanopages
Authors: E. Horváth, P. L. Neumann, A. L. Tóth, É. Vázsonyi, A. A. Koós, Z. E. Horváth, P. Fürjes, C. Dücső and L. P. Biró

The deposition of nanowires for interconnects in nanoelectronic devices werestudied morphologically by scanning electron microscopy (SEM), atomic force microscopy (AFM) and by in-situ resistance measurements. The deposition and basic characterization of nanometer size tungsten wires by gas injection (GIS) and focused ion beams (FIB) was carried out in-situ in a LEO 1540 XB workstation. The I(V) measurement showed that the deposited W wires have ohmic characteristic. The variation of the resistance during an ex-situ heating was linear with a low thermal coefficient (4% of the pure metallic W).

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Non-linear analysis of steel semi-rigid diagonal-to-column joint is presented in the paper. Investigated joint is a part of a structural system, which was often used in Slovakia. The results from analysis will help with the correct preparation of a test. Evaluation of stiffness and resistance of this joint is the purpose. These parameters are the input values for efficient analysis of structures by component method. The aim of work is to detect joint resistance under cyclic loading and to identify its failure mechanism. Final aim is to establish the influence of joints to the whole structure.

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The rheological properties of seven winter wheat cultivars from two harvest years were studied. Rheological testing included two empirical rheological methods, alveograph and extensograph. Principal component analysis on the studied rheological parameters showed that the alveograph and extensograph parameters are influenced by entirely different factors. The first component was responsible solely for the extensograph parameters, primarily for the resistance properties of dough samples. The second component affected the extensograph extensibility (E) and alveograph tenacity (P) parameters as well, in spite of the fact that these parameters refer to different properties of dough. The third component explained only alveograph parameters, such as P, L and G values. The Pearson’s correlation coefficients showed that the extensograph area parameter primarily depends on the maximum resistance to extension of dough (r=0.91). The extensibility and resistance at a constant extension of 5 cm properties did not show such strong relationship with the area parameter (r=0.56 and 0.65, respectively). The relationship between the extensograph maximum resistance and extensibility parameters was positive (r=0.20), while the correlation coefficient between alveograph P and L value was negative (r=0.34).

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This paper presents the measurements of bulk density, matrix density, total open porosity, water absorption coefficient, water vapor diffusion resistance factor and thermal conductivity of hydrophilic mineral wool Front — Rock Max E. Front — Rock Max E consisted of two layers fasten together, namely a low-density and high-density layer.

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Our experiments were based on a model solution containing five of the main pineapple aroma components. Both sweeping-gas pervaporation and vacuum-pervaporation methods were carried out. Measurements were performed at different temperatures and feed flow rates. The purposes of this study were to examine applicability of the two pervaporation methods in reference to the pineapple aroma recovery, the effects of the operating parameters on the process, and modelling the pervaporation process by resistance-in-series model. Higher enrichment could be reached with vacuum-pervaporation than the sweeping-gas method. The separation process is determined by the diffusion of compounds in the membrane, thus the resistance in the boundary layer at liquid side is negligible. Based on performed experiments, the pervaporation process can be applied in beverage industry for aroma recovery.

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Among nanotechnology-based thermal insulation materials thermodynamic performance of nano-ceramic coatings generates intensive discussions. Complete agreement has not been found yet about the mechanism of their insulating effect. In the Laboratory of Building Materials and Building Physics at Széchenyi István University (Győr, Hungary) heat transfer resistance experiments have been performed in order to describe thermodynamic processes inside nano-ceramic coatings. Previous studies finding after new measurements conducted in 2016-2017 also supported the former assumption that in case of nano-ceramic coatings convective heat transfer coefficient might be taken into account in a different way. Results also showed that thermal insulating effect of nano-ceramic coatings could be caused by a relatively high surface heat transfer resistance.

Open access
Nanopages
Authors: E. Zsolt Horváth, A. Antal Koós, Krisztián Kertész, Zofia Vértesy, György Molnár, Mária Ádám, Csaba Dücső, József Gyulai and P. László Biró

Gas sensing properties of different carbon nanotube (mostly multiwall, MWCNT) mats, based on electrical resistance measurement were investigated in a simple arrangement and found that the sensitivity for different gases or vapors highly depends on the pre-treatment and functionalization of nanotubes. The selectivity of the sensing was demonstrated by building a vapor recognition system based on an array of multitube sensors made of differently functionalized MWCNTs.

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Nanopages
Authors: P. Neumann, Z. Horváth, P. Nemes-Incze, G. Molnár, G. Vértesy and L. Biró

We studied the electrical transport properties of indium contacted graphene, few layer graphite (FLG) and bulk graphite samples under ambient conditions. Some of the contacted samples showed nonlinear transport characteristics. The initial electrical properties of the samples were changed reversibly by light illumination and irreversibly by argon ion irradiation. Ion irradiation modified the nonlinear I–V characteristics to quasi-linear ones in many cases. The resistance of a graphene sample showed positive temperature coefficient.

Open access

The concept of structures reliability conditions besides safety also must provide adequate durability and service life. According to EN 1990 reliability should be considered as its ability to fulfil the specific requirements, including the designed working (service) life. The structure and structural members should be designed executed and maintained in such a way that during their intended life, with appropriate degrees of reliability and in economic way, they will have adequate structural resistance, serviceability, durability and robustness.

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