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- ItemThe field of solid solutions in ternary system of synthetic apatite-type alkaline earth element-yttrium-silicate oxybritholite phases of the composition: AEE(delta)Y(10-delta)[SiO4](6)O3-0.5 delta, where AEE=Ca, Sr and Ba(Elsevier Ltd, 2016-01-08) Ptáček, Petr; Opravil, Tomáš; Šoukal, František; Tkacz, Jakub; Másilko, Jiří; Bartoníčková, EvaThis contribution deals with the synthesis, properties and investigation of the field of solid solutions formed between the three end-members of apatite-type alkaline earth element-yttrium-silicate oxybritholites with the hexagonal structure (P6(3)/m). The stoichiometric composition of these compounds corresponds to the formula AEE(delta)Y(10-delta)(SiO4)(6)O3-0.5 delta, where AEE=Ca, Sr and Ba and parameter delta -> 2. These compounds and their solid solutions crystallize from non-equilibrium high temperature flux as the main product of sinter-crystallization process. Increasing ionic radius of AEE cations has significant effect to the lattice parameters, properties and miscibility of apatite phases. While there is non-limited miscibility of solid solutions formed between Ca2Y8[SiO4](6)O-2 and Sr2Y8[SiO4](6)O-2, the highest content of barium in the binary solution with these species is limited to 28% and 38%, respectively. The connecting line of these points marks out the borderline for the field of solid solutions in the ternary system. All attempts for the preparation of pure Ba2Y8[SiO4](6)O-2 end-member via the ceramic method were not successful.
- ItemDetermination of Critical Parameters of Drug Substance Influencing Dissolution: A Case Study(Hindawi Publishing Corporation, 2014-09-15) Bojňanská, Erika; Kalina, Michal; Pařízek, Ladislav; Bartoníčková, Eva; Opravil, Tomáš; Veselý, Michal; Pekař, Miloslav; Jampílek, JosefThe purpose of this study was to specify critical parameters (physicochemical characteristics) of drug substance that can affect dissolution profile/dissolution rate of the final drug product manufactured by validated procedure from various batches of the same drug substance received from different suppliers.The target was to design a sufficiently robust drug substance specification allowing to obtain a satisfactory drug product. For this reason, five batches of the drug substance and five samples of the final peroral drug products were analysed with the use of solid state analysis methods on the bulk level. Besides polymorphism, particle size distribution, surface area, zeta potential, and water content were identified as important parameters, and the zeta potential and the particle size distribution of the drug substance seem to be critical quality attributes affecting the dissolution rate of the drug substance released from the final peroral drug formulation.
- ItemInfluence of Pb Dosage on Immobilization Characteristics of Different Types of Alkali-Activated Mixtures and Mortars(Hindawi, 2018-01-11) Koplík, Jan; Pořízka, Jaromír; Kalina, Lukáš; Másilko, Jiří; Březina, MatějAlkali-activated matrices are suitable materials for the immobilization of hazardous materials such as heavy metals.. is paper is focused on the comparison of immobilization characteristics of various inorganic composite materials based on blast furnace slag and on the influence of various dosages of the heavy metal Pb on the mechanical properties and fixation ability of prepared matrices. Blast furnace slag (BFS), fly ash, and standard sand were used as raw materials, and sodium water glass was used as an alkaline activator. Pb(NO3)(2) served as a source of heavy metal and was added in various dosages in solid state or as aqueous solution. The immobilization characteristics were determined by leaching tests, and the content of Pb in the eluate was measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). The microstructure of matrices and distribution of Pb within the matrix were determined by scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). Increasing the dosage of the heavy metal had negative impacts on the mechanical properties of prepared matrices. The leaching tests confirmed the ability of alkali-activated materials to immobilize heavy metals. With increasing addition of Pb, its content in eluates increased.
- ItemInfluence of Barium Oxide Additions on Portland Clinker(Institute of Rock Structure and Mechanics of The Czech Academy of Sciences, v. v. i., 2017-01-02) Zezulová, Anežka; Staněk, Theodor; Opravil, TomášNowadays, nuclear power plants are widespread around the world and research is of great interest. Together with nuclear research, shielding of different types of radiation is an important current topic of research aiming at their safety. Portland cement has been an elementary building material for centuries. Since barium is very efficient in shielding different types of radiation, it can be assumed that the radiation shielding capability of cement can be improved by incorporation of barium. This work deals with the influence of barium oxide, added in the form of barium carbonate and sulphate, on the formation and properties of Portland clinker. The structure of burnt clinkers and the ratio of clinker phases were studied by polarizing microscopy and by X-ray diffraction. With increasing barium content, the alite-belite ratio decreases and the content of free lime gradually increases. Moreover, sulphates induce the growth of alite crystals. The ability of barium to be a part of the clinker minerals was observed by scanning electron microscopy. Belite and clinker melt contain the highest amount of barium, but aggregates of barium oxide are formed in the clinker melt. Furthermore, the rate of alite crystallization was studied under isothermal conditions.
- ItemPossibilities of elimination of ammonia slip from technological water in power plants(IOP Publishing, 2018-07-12) Hajzler, Jan; Opravil, Tomáš; Pořízka, Jaromír; Ptáček, PetrThe purpose of this study is to find new possibilities of elimination or separation of ammonium compounds from technological water produced by powerplants and incinerators, in which the secondary flue gas denitrification methods have been implemented (SCR, SNCR). This paper seeks for a new method of ammonium slip elimination from technological water due to the absence of industrially applicable method and thus fixation of ammonium ions in composite cement eventually in binder containing fly ash. The experiments confirmed the validity of the complex compound utility in given issue. The new method consists in adding a soluble cobalt compound to get an insoluble cobalt complex, the processing conditions were optimized during laboratory testing.