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Abstract

Proper understanding of sorption behaviour of the materials is important from the point of view of fundamental research and technology as well for applied building technology. In this paper a simple method is presented for measuring water sorption capability of solid bodies. Moisture sorption and desorption measurements were carried out on soil samples by using climatic chamber. After drying the samples in a Venticell 111 type drying equipment they were treated with a Climacell 111 type climate chamber, where the relative humidity (RH) was varied from 40 to 83% at 22°C for different times (40, 80, 120 and 240 minutes). The samples reached the equilibrium moisture content after 120 minutes for sorption. The desorption isotherm measurements were carried out at 22°C for 80 minutes of exposure at constant RH. At this point hysteresis phenomenon was observed. Besides the moisture content figures the time evolution of the damping process is also presented in this paper.

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Recently, it has become extremely important to reduce the heating energy demand and the CO2 emission of buildings. This reduction can easily be achieved by insulating the shell of buildings. By thermal insulation not only the heating energy demand can be reduced but also higher thermal efficiency can be reached. Therefore, measurements, calculations and simulations are carried out on the energy efficiency of buildings. Furthermore, the combination of methods is of great importance. Combination of experiments with building simulations solution can make design practices and sizing processes easier in the investigation of building performance. The purpose of this article is to demonstrate how the energy balance of a building can be changed in function of the wet building envelope in the Central European Region. A real and available building (old family house) was tested and it was placed (hypothetically) in three different countries (Austria, Hungary and Slovakia). In this study two types of load-bearing structures (brick and concrete) covered with four different types of insulations (mineral wool, expanded polystyrene, graphite-doped expanded polystyrene, and extruded polystyrene) were tested. The change in the heating energy of the building in three different countries by the function of measured water contents of the thermal insulators was simulated by CASAnova simulation software.

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Abstract

These days, the investigations of the physical properties of the insulating materials are very important. In this paper we report the measured water uptaking capabilities of a thermal insulating paint. They can be found in liquid phase, but we measured dried solid samples. The thin thermal insulators (insulator coatings) are starting to spread on the market of the building materials. The proper understanding of sorption behavior of the materials is important from the applied building technology point of view. Moisture sorption and desorption measurements were carried out on two samples with different geometry by using climatic chamber method. After drying the samples at 90 °C for one hour in the Venticell 111 type drying equipment they were wetted with a Climacell 111 type climate chamber, where the relative humidity (RH) was varied from 25% to 90% at 293 K for 2 hours. The samples were wetted for 2 and 4 hours as well. Sorption and desorption as well as kinetic curves are presented in this paper.

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The development of high performance insulating materials incorporating nanotechnologies has enabled considerable decrease in the effective thermal conductivity. Besides the use of conventional insulating materials, such as mineral fibers, the adoption of new nano-technological materials such as aerogel, vacuum insulation panels, graphite expanded polystyrene, is growing. In order to reduce the thermal conductivity of polystyrene insulation materials, during the manufacturing, nano/micro-sized graphite particles are added to the melt of the polystyrene grains. The mixing of graphite flakes into the polystyrene mould further reduces the lambda value, since graphite parts significantly reflect the radiant part of the thermal energy. In this study, laboratory tests carried out on graphite insulation materials are presented. Firstly, thermal conductivity results are described, and then sorption kinetic curves at high moisture content levels are shown. The moisture up-taking behaviour of the materials was investigated with a climatic chamber where the relative humidity was 90% at 293 K temperature. Finally, calorific values of the samples are presented after combusting in a bomb calorimeter.

Open access
Acta Alimentaria
Authors: V. Kapcsándi, A.J. Kovács, M. Neményi, and E. Lakatos

The aim of our experiments was to demonstrate the non-thermal effect of microwave treatment on Saccharomyces cerevisiae fermentation activity. A method was developed for studying the effects of various treatments in the course of must fermentation. The raw material (must) was treated in different ways: (i) heat transfer; (ii) microwave treatment; (iii) inoculation with yeast, and (iv) their combinations. The results of the treatments were compared with respect to alcohol concentration, sugar content, and acidity. The results proved that sugar content of the treated samples rapidly decreased compared to the control sample, and fermentation time was 40% shorter in the fastest case. These results can be explained by the yeast inoculation and microwave treatment. Due to non-thermal effects, fermentation capacity increased by about 30%, while the energy consumption decreased.

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The laboratory investigations of the heat transfer properties of wall structures are very significant from the point of view of designing the buildings. In this article measurements and calculations will be presented in order to manifest the effect of the forced and un-forced convection of air at the cold surface of the wall. A steady-state method for measuring the thermal resistance of wall structures with Hukseflux apparatus is presented in this article. The measurements were accomplished through, firstly on an un-insulated inbuilt plaster/brick/plaster wall construction and later it was covered with a 0.013 m thick aerogel layer blanket. Aerogels are nanoporous lightweight materials, were discovered more than 70 years ago. In these years their applications are truly spread over. During the investigations the wall structures were tested without forcing the air to motion, and then measurements were carried both on the insulated and un-insulated wall structures, where the movement of the air was forced by a ventilator from three different directions with the same 1 m/s velocity near the wall.

Open access
Acta Alimentaria
Authors: P. Olejníková, A. Kaszonyi, M. Šimkovič, B. Lakatoš, M. Kaliňák, M. Valachovičová, and L. Birošová

The human endogenous intestinal microbiota is an essential “organ” in providing nourishment, regulating epithelial development, and instructing innate immunity. Even though lots of scientists have evaluated the content of gut microbiota from various points of view, we examined the content of intestinal microbes in the group of healthy middle aged volunteers (40–60) form Slovakia. We have compared faecal cultivable microbiota of vegetarians and omnivores. We have found that the composition of the human microbiota is fairly stable, and it seems that the major microbial groups on species level that dominate the human intestine are conserved in all individuals regardless of dietary habits. Beside the microbial content we have examined the faecal samples also for the presence of antimicrobial active compounds, potential mutagens, and faecal sterols.

Open access
Acta Alimentaria
Authors: K. Szentmihályi, A. Blázovics, I. Kocsis, Edit Fehér, B. Lakatos, and Péter Vinkler

The metabolic alteration of fatty liver causes significant changes in the composition of bile fluid secreted by epithelial liver cells. These processes include both organic molecular and inorganic ion content changes in bile juice as well. In this work ion concentration differences of bile fluid in experimental hyperlipidemic rats compared to normal ones were monitored. Fatty liver in young male Wistar albino rats was induced by 2% cholesterol, 20% sunflower oil and 0.5% cholic acid added to the normal food and 3% alcoholic water was administered to rats for 9 days. The development of hyperlipidemy was detected by measuring serum parameters and fatty liver was proved by morphological investigations. The ion concentrations of bile fluid samples were determined by ICP-OES (inductively coupled plasma optical emission spectrometry). The bile fluid samples were digested with a mixture of HNO3 and H2 O2 . The results show that the concentration of calcium and phosphorus in bile juice increased significantly in hyperlipidemic rats compared to the control. Significant concentration changes have also been detected for chromium and manganese. The changes in metal ion metabolism also point to the damage of liver cells owing to metal complex evacuation.

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