Institute of Rock Structure and Mechanics

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2019-11-25
10:16
The processing of stabilized sewage sludge by high-temperature slow pyrolysis and gasification
Bičáková, Olga ; Čimová, Nikoleta ; Vöröš, Dominik ; Náhunková, Jana ; Řimnáčová, Daniela
One of the most challenging type of waste is sewage sludge, which is a heterogeneous suspension containing organic and inorganic substances and pathogenic organisms. This work focuses on an effective application method for the sewage sludge, which is usually deposited in landfills or co-incinerated in power plants. High temperature pyrolysis and gasification at 700–900 °C were applied to the samples of stabilized sewage sludge. The samples with a constant weight of 100 g were heated in a stationary bed, with the rate of batch heating being monitored. During the heating process, volatile products were released and the composition of the gaseous products developed during the heating was analyzed. Afterwards, the mass balance of the resulting products was evaluated. The elemental and textural analyses of the products were performed. Furthermore, it has been found that the solid residue has a porous texture and properties suitable for the removal and capture of pollutants. \n

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2019-11-25
10:16
Three-dimensionally ordered micromesoporous carbon as adsorbent for CO2 capture
Vorokhta, Maryna ; Řimnáčová, Daniela ; Pilař, Radim
In this work, ordered three-dimensionally micromesoporous carbon composed of large spherical mesopores 13 nm in diameter and small micropores with a mean micropore width of 1.46 nm, connecting the main spheres, was synthesized and investigated for CO2 capture ability at temperatures of 25°C, 35°C and 50°C, and at pressures up to 6.5 MPa. Because of the big pore volume occupying 3.62 cm3/g, composed of mesopores and micropores, the carbon sample showed very high adsorption capacity at high pressures. The highest CO2 adsorption capacity of 24.03 mmol/g was obtained at 25°C and at 5.5 MPa. As the temperature increased, the CO2 adsorption capacity decreased to 13.34 mmol/g at 50°C and at 6.5 MPa. The Freundlich fittings of the measured adsorption isotherms at pressures up to 2 MPa showed very high correlation coefficients. The estimated isosteric heats of adsorption in the range of 5.62-6.90 kJ/mol indicated a physical adsorption process, and suggested a stronger interaction between CO2 molecules than between CO2 molecules and the surface of the carbon sample.

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2019-11-25
10:16
Adsorption studyof waste materials as potential adsorbents for pollutant removal and storage
Řimnáčová, Daniela ; Vorokhta, Maryna ; Vöröš, Dominik ; Borecká, Lenka ; Bičáková, Olga
The study shows how changing the experimental conditions during carbonization of a waste material such as sewage sludge influences textural properties and the CO2adsorption capacity of final carbonized productsin their potential use for removaland storage of pollutantssuch as carbon dioxide. The CO2adsorption measurements were done with gravimetric and manometric sorption devices in a wide range of pressures and temperatures. Further, CO2adsorption capacities of other materialssuch as activated carbon prepared from black carbon and a Czech Silurian shalewere compared toadsorption capacities of the studied carbonized sewage sludge. These two compared materials were chosen according to their compositionsand porosity.The porosityof the studied materials was determined from the N2sorption isotherms and measurements of their skeletal density with He.The adsorption capacity depended on the ratio of micropores and mesopores in the carbonized sewage sludge, because CO2fillsmicropores and mesopores at lowand highpressures, respectively, and was decreasing with the temperature increase atconstant pressure.The adsorption capacity of the carbonized sewage sludgewas increased by increase inthe carbonization temperature.The obtained adsorption capacities showed that the carbonization of sewage sludge can lead to preparation of perspective adsorbents for CO2capture and storage.

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2019-08-26
09:04
A COMPARISON OF THE CENTRIFUGAL FORCE SPINNING AND ELECTROSPINNING OF COLLAGEN UNDER DIFFERENT CONDITIONS
Hlavatá, J. ; Suchý, Tomáš ; Šupová, Monika ; Pokorný, M. ; Košťáková, E.
Collagen makes up one of the most important parts of the extracellular matrix and connective tissue. Collagen type I accounts for up to 90% of the collagen found in the body and it can be isolated and purified in large quantities and processed into a variety of forms. With respect to the process of the treatment of collagen into the nano-fibrous and submicron-fibrous forms, severe conditions leading to the denaturation of the collagen and thus the gelatin content should be avoided. Centrifugal force spinning and electrospinning processes appear to present promising methods for the spinning of collagen solutions. This paper deals with a comparison of the various methods applied in the processing of collagen, i.e. principally needle and needleless centrifugal spinning technology and electrospinning technology. In addition, the effect of process parameters and collagen solution conditions on the final form of the material was analyzed. Spun layers were prepared based on collagen type I isolated from calf skin. Nano-structured layers were prepared employing the spinning of 4-16 wt% collagen solutions in phosphate buffer saline and ethanol. The layers thus prepared were characterized by means of scanning electron microscopy and Fourier transform infrared spectroscopy.

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2018-11-15
12:40
Chemické vlastnosti odpadních sádrovců z různých energetických zdrojů
Kroulíková, S. ; Mercl, F. ; Száková, J. ; Perná, Ivana ; Tlustoš, P.
V rámci studie byly porovnávány hodnoty pH, obsahy živin a vybraných rizikových prvků v sádrovcích ze čtyř významných energetických zdrojů v České republice. Zároveň byl hodnocen jejich potenciál pro zemědělské využití. Dle našich výsledků jsou odpadní sádrovce významným zdrojem síry 17,8 – 19,0 %) a vápníku (23,0 – 30,2 %) a mohou tak snížit nedostatek těchto živin v půdě. Nicméně u tří testovaných sádrovců byl stanoven nadlimitní obsah arsenu a rtuti. Pouze jeden sádrovec vyhověl legislativně a obsah všech hodnocených rizikových prvků byl pod limitními hodnotami. Nezbytné je tento materiál dále testovat v modelových i polních podmínkách a zhodnotit jeho využití v zemědělství jako levnější alternativu k běžným minerálním hnojivům se sírou.\n\n\n

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2018-03-09
13:20
Field measurement of natural electromagnetic emissions near the active tectonic and mass-movement fractures in caves
Trčka, T. ; Macků, R. ; Koktavý, P. ; Škarvada, P. ; Baroň, I. ; Stemberk, Josef
Laboratory tests on a wide range of solid materials shoved that the electromagnetic emission (EME) signals are generated during the samples mechanical stress. EME anomalies have been observed also under natural conditions in association to fracture processes, tectonic loading, stress redistribution and crack propagation prior to earthquake or in relation to deep-seated gravitational mass movements. This paper describes a first prototype of the Emission data logger, which was specially developed for the continual EME monitoring in field conditions. Our equipment has been installed and tested in Obir Caves (Austria) at an active tectonic fault. The pilot long-term EME measurement results from this location are also presented in this paper.

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2018-03-09
13:20
Valley evolution of the Biala Lądecka drainage network during late Cenozoic, Lower Silesia, Poland
Stemberk, Jakub ; Štěpančíková, Petra ; Tábořík, Petr ; Coubal, Miroslav
Biala Lądecka (Biala Kłodzka) river is located in Lower Silesia (Poland) and its valley separates Góry Złote Mts.\n(Rychlebské hory Mts.) on the NE from Góry Bialskie Mts. on the SW. We conducted geomorphic investigations on the Biala\nLądecka river basin, in order to determine if Quarternary tectonic activity at the Bělský fault (or near Marginal Sudetic fault) is\ncontributing to the river’s asymmetry. Our research was focused on analysis of selected landforms, DEM parameters,\nmorphometric indexes and their spatial distribution which could potentially indicate recent tectonic activity in the area. At\nselected places geophysical measures were used to discover proper location and structure of Bělský fault or presence of\nsuggested morpholineaments. Preliminary results suggest a Quaternary tectonic activity for the Bělský fault. Moreover we tried\nto clarify nowadays stress regime in study area based striae measurement on fault planes and precise monitoring of selected\nfaults using TM-71 device.

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2018-03-09
13:20
Late Quaternary activity of slow-slip intraplate Mariánské Lázně fault as revealed by trenching and shallow geophysical survey; Bohemian Massif (Czech Republic, central Europe)
Štěpančíková, Petra ; Fischer, T. ; Hartvich, Filip ; Tábořík, Petr ; Rockwell, T. ; Stemberk, Jakub ; Široký, J. ; Sana, Hamid
The NNW-SSE trending Mariánské Lázně Fault (MLF) zone is situated in the western part of the Bohemian Massif (Czech\nRepublic, central Europe) where it intersects NE-trending Cenozoic Eger rift. The northern segment of the MLF controls the\nmorphologically pronounced mountain front of Krušné hory Mts. and eastern limit of Cenozoic Cheb basin, which is famous for\nearthquake swarms (max. ML=4.6) and CO2 emanation. We performed 2D and 3D geophysical survey (electric resistivity\ntomography, ground penetration radar) and 3D trenching to look for large surface-rupturing prehistoric earthquake responsible\nfor pronounced moutain range front. Seven excavated and six hand-dug trenches revealed a complex geology and deformation\nat the study site probably as a result of right-lateral transpression during Late Quaternary. Two Holocene earthquakes 1150-590\nBC and 780-1000 AD were inferred from 14C dating of faulted Holocene colluvium with corresponding magnitudes Mw=6.7-7.0.\nThe latter one is the youngest documented surface-rupturing event in central Europe.\n

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2018-03-07
15:28
Optimizing and Evaluating the Biocompatibility of Fiber Composites with CaP Additives
Suchý, Tomáš ; Sucharda, Zbyněk ; Balík, Karel ; Sochor, M. ; Bačáková, Lucie
Composite materials based on a polyamide fabric (aramid) and a polydymethyl-siloxane (PDMS) matrix were designed for application in bone surgery. In order to increase the bioactivity, 2, 5, 10, 15, 20 and 25 vol. % of nano/micro hydroxyapatite (HA) and tricalcium phosphate (TCP) were added. The effect of the additives on the biocompatibility was studied. It appears that nano additives have a more favorable effect than micro particles on mechanical properties. For final application of the composites as substitutes for bone tissues, 15 vol. % of nano hydroxyapatite additives is an optimum amount: in this case both the mechanical properties and the biological properties are optimized without distinct changes in the inner structure of the composite.

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2017-12-07
15:36
Hydrogen charging of fuel cladding methodology
Krejčí, J. ; Kabátová, J. ; Kočí, J. ; Weishauptová, Zuzana ; Vrtílková, V.
Hydrogen content is a very important parameter for mechanical properties of fuel cladding. The methodology of developed hydrogen charging is described.

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