ICCHP Summer University - letní škola matematiky pro studenty se zrakovým postižením

Ve dnech 9. - 13. července 2012 proběhl již 3. ročník ICCHP Summer Univerzity - letní školy matematiky pro studenty se zrakovým postižením. V příspěvku se blížeji seznámíme s touto mezinárodní akcí, s jejím posláním a historií. Dále budou představeny workshopy, které byly doposud nabídnuty zrakově postiženým účastníkům ICCHP Summer University pracovníky Střediska Teiresiás Masarykovy univerzity.Ve dnech 9. - 13. července 2012 proběhl již 3. ročník ICCHP Summer Univerzity - letní školy matematiky pro studenty se zrakovým postižením. V příspěvku se blížeji seznámíme s touto mezinárodní akcí, s jejím posláním a historií. Dále budou představeny workshopy, které byly doposud nabídnuty zrakově postiženým účastníkům ICCHP Summer University pracovníky Střediska Teiresiás Masarykovy univerzity.On 9-13 July 2012, the 3rd year of ICCHP Summer University on Maths, Science and Statistics for Blind and Partially Sighted Students took place. This paper describes this international event, its mission and history. Furthermore, workshops that have been so far offered to visually impaired participants of ICCHP Summer University by the staff of Masaryk University’s Teiresias Centre will be presented

Synthesis of High-Strength Composites Based on Inorganic Cement and Polymer

Předmětem disertační práce je studium odolnosti vůči vlhkosti macro-defect-free (MDF) kompozitů založených na bázi hlinitanového cementu a polyvinylalkoholu jako polymeru. MDF cementy jsou perspektivní materiály, které mají do budoucna velký potenciál v oblasti konstrukčního využití. Jejich základním nedostatkem je ovšem snížená odolnost proti vodě s následným nabobtnáním a redukcí pevnosti. Proto se tato práce soustředí na sledování účinku organického polymeru s ohledem na odolnost vůči vodě a fázové změny ve struktuře MDF kompozitů. Byly zkoumány efekty tří různých organotitanátových činidel na vlastnosti MDF vzorků. Tyto vzorky vykazují ve srovnání se standardními vzorky lepší odolnost proti vlhkosti pokud byly vystaveny 100 % relativní vlhkosti či vodě za laboratorních podmínek. Na základě výsledků měření byl pozorován vliv složení, podmínek tvrdnutí a jednotlivého uložení na vlastnosti modelových MDF cementů. Charakterizace MDF vzorků byla především založena na metodách zkoušky pevnosti v tahu za ohybu, XRD, DTA/TGA ve spojení s EGA, EDS a skenovací elektronové mikroskopie.The subject of the doctoral thesis is the study of moisture resistance of macro-defect-free (MDF) composites based on calcium-aluminate cement and polyvinylalcohol used as polymer. MDF cements are perspective materials providing unique properties relative to traditional cement pastes with great potential to incoming constructional utilization. But it is known that MDF cements exhibit sensitivity to water, with swelling and reduction of strength. Therefore the work is aimed in monitoring of an organic polymer effect on the moisture resistance of MDF materials and phase changes. The effects of three different organotitanate cross-linking agents on the properties were investigated. The organotitanate-modified MDF cement samples exhibited improved moisture resistance as compared to the standard samples when exposed to 100 % relative humidity or water at laboratory conditions. The influence of composition at different curing on the properties of model MDF cement samples was observed. The characterization of MDF samples was based especially on test of flexural strength, XRD, DTA/TGA and EGA, EDS and scanning electron microscopy analyses.

Increases in water resistance of MDF composites

Obsahem diplomové práce je studium odolnosti vůči vlhkosti macro-defect-free (MDF) cementu založeného na bázi kalcium-aluminátového cementu a polyvinylalkoholu jako polymeru. MDF cementy jsou perspektivní materiály, které mají do budoucna velký potenciál v oblasti konstrukčního využití. Jejich základním nedostatkem je ovšem právě snížená odolnost proti vodě s následným nabobtnáním a redukcí pevnosti. Proto se tato práce soustředí na sledování fázových změn ve struktuře MDF vzorků v závislosti na obsahu organického polymeru a podmínkách tvrdnutí v průběhu vystavení vlhkosti. Pro syntézu MDF vzorků byl použit hlinitanový cement (SECAR 51) a kopolymer polyvinylalkohol/acetát. Odolnost modelových MDF vzorků vůči vlhkosti byla sledována při dvou různých uloženích: ve vlhké atmosféře a pod vodou. Na základě výsledků měření byl pozorován vliv složení, podmínek tvrdnutí a jednotlivého uložení na vlastnosti modelových MDF cementů. Charakterizace MDF vzorků byla především založena na metodách zkoušky pevnosti v ohybu, FT-IR, EDAX a na optické mikroskopii.The subject of the diploma thesis is the study of moisture resistance of macrodefect-free (MDF) cements based on calcium-aluminate cement and polyvinylalcohol used as polymer. MDF cements are perspective materials providing unique properties relative to traditional cement pastes with great potential to incoming constructional utilization. But it is known that MDF cements exhibit sensitivity to water, with swelling and reduction of strength. Therefore the work is aimed in monitoring of an organic polymer effect on the moisture resistance of MDF materials and phase changes. Aluminate cement (SECAR 51) and polyvinylalcohol/acetate copolymer have been used for the MDF cement preparation. The moisture resistance of model MDF cement samples was investigated at two different curing conditions: in the moist atmosphere and immersed in water. The influence of composition and individual curing on the properties of model MDF cement samples was observed. The characterization of MDF samples was based especially on test of flexural strength, FT-IR, EDAX and optical microscopy analyses.

The effect of heat-treatment on properties of Ni-P coatings deposited on AZ91 magnesium alloy

The present study reports the effect of phosphorus content in deposited electroless nickel (Ni–P) coatings, the heat treatment on the microhardness and its microstructural characteristics, and the influence of the temperature on the microstructure of the Mg alloy substrate during the heat treatment. The deposition of Ni–P coatings was carried out in the electroless nickel bath, and the resulting P content ranged from 5.2 to 10.8 wt.%. Prepared samples were heat-treated in the muffle furnace at 400 °C for 1 h after the coating deposition. The cooling of the samples to room temperature was proceeded in the air. For as-deposited and heat-treated samples, it was determined that with the increasing P content, the microhardness was decreasing. This may be caused by the changes in the structure of the Ni–P coating. The X-ray diffraction patterns of the as-deposited Ni–P coatings showed that the microstructure changed their nature from crystalline to amorphous with the increasing P content. The heat treatment of prepared samples led to the significant increase of microhardness of Ni–P coatings. All the heat-treated samples showed the crystalline character, regardless of the P content and the presence of hard Ni3P phase, which can have a positive effect on the increase of microhardness. The metallographic analysis showed changes of substrate microstructure after the heat treatment. The prepared coatings were uniform and with no visible defect

The Characterization of Fixation of Ba, Pb, and Cu in Alkali-Activated Fly Ash/Blast Furnace Slag Matrix

The fixation of heavy metals (Ba, Cu, Pb) in an alkali-activated matrix was investigated. The matrix consisted of fly ash and blast furnace slag (BFS). The mixture of NaOH and Na-silicate was used as alkaline activator. Three analytical techniques were used to describe the fixation of heavy metals—X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS), and X-ray powder diffraction (XRD). All heavy metals formed insoluble salts after alkaline activation. Ba was fixed as BaSO4, and only this product was crystalline. EDS mapping showed that Ba was cumulated in some regions and formed clusters. Pb was present in the form of Pb(OH)2 and was dispersed throughout the matrix on the edges of BFS grains. Cu was fixed as Cu(OH)2 and also was cumulated in some regions and formed clusters. Cu was present in two different chemical states; apart from Cu(OH)2, a Cu–O bond was also identified

Crushed bricks as aggregate in cement based binder

The work deals with the impact of crushed brick on properties of Portland cement binder. The source of brick recycled materials is not only the demolition waste, but also the waste from brick production. One way to reduce the amount of this recyclate is to use it in cement-based composite. The advantages of using bricks as aggregate are their lower bulk density compared to conventional aggregates. Economic and ecological benefits are also important, because less natural sources need to be mined. First, the phase composition of used brick aggregate, its particle size and morphology were analysed. Test specimens with different content of brick recyclate were prepared and tested for the mechanical properties. Subsequently, the microstructure of prepared samples was examined using a scanning electron microscope. The phase composition of samples was analysed by X-ray diffraction analysis

The determination of the influence of pH value of curing conditions on Portland cement hydration

Water composition during cement hydration can be changed due to migration of ions from the cement matrix to the solution. The storage of various materials together can lead to transfer of various ions and distortion of results. This article is aimed on the influence of storage environment on the Portland cement hydration and hydrated samples composition. Test specimens were prepared and stored in different environments. Storage environments were ultrapure water and solutions having alkaline and acidic pH value. The mechanical properties were measured after 1, 7 and 28 days. Composition of samples stored in different environment was tested by X-ray diffraction and DTA analysis. (C) 2016 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license

Phase Composition of Silica Fume-Portland Cement Systems Formed under Hydrothermal Curing Evaluated by FTIR, XRD, and TGA

Two substitution levels of Portland cement by silica fume (SF; 30 and 50 mass%) and three hydrothermal treatment regimes (0.5, 1.2, and 2 MPa and 165, 195, and 220 degrees C for 7 days, respectively) were selected for the investigation of high-temperature phase formation. A combination of thermogravimetric, X-ray diffraction, and Fourier transform infrared analyses in the mid-IR region was used to overcome the shortcomings of individual techniques for the identification of these complex systems. Changes in molecular water amounts, the polymerization degree of silicate chains, or their decomposition due to transformations and crystallization of phases at hydrothermal conditions were observed and discussed concerning composition. Contrary to the calciochondrite, hydrogrossular phases, alpha-C2SH, and jaffeite detected in the systems without SF, a decrease in CaO/SiO2 ratio resulted in the formation of stable tobermorite in the case of 30 mass% SF, whilst calcium hydrogen silicate, gyrolite, and cowlesite were identified as more thermally stable phases in the samples with 50 mass% SF