National Repository of Grey Literature 85 records found  beginprevious47 - 56nextend  jump to record: Search took 0.00 seconds. 
Mercury Removal from Waste Incineration Flue Gas: Heterogeneous Oxidation and Capture by Waste-Derived Fly Ashes.
Rumayor, Marta ; Pohořelý, Michael ; Šyc, Michal ; Svoboda, Karel ; Švehla, Jaroslav
During waste incineration, all Hg-content is released primarily as elemental mercury (Hg0) which passes into the flue gas and is gradually oxidized. Mainly HgCl2 is formed, by both homogeneous and heterogeneous reactions. Some degree of Hg removal is achieved by existing conventional air pollution control devices (APCDs), normally used to control NOx, SO2, and dust emissions. In this study, three samples of fly ashes from boiler and ESP (characterized by composition, surface area and carbon content) derived from MSW incineration were assessed for mercury removal under MSW incineration conditions in a laboratory scale, using a fixed-bed reactor packed with fly ash. The results obtained showed that unburnt carbon content, composition of flue gas (e.g. mainly HCl and SO2 content) and operating temperature are important variables controlling capture of mercury by fly ash.
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Development of a Pilot Plant for Reduction Hg Emission from Large Power Plant.
Pilař, L. ; Veselý, Václav ; Vlček, Z. ; Zseliga, Z.
This paper deals with the research project The development of the pilot plant for monitoring of the mercury emissions reduction from large and medium capacity energy sources. In this paper are presented project results reached in the year 2016.\n
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Factors influencing electrochemical oxidation of m-cresol at boron-doped diamond electrode
Procházková, Kateřina ; Schwarzová, Karolina (advisor) ; Vyskočil, Vlastimil (referee)
This study investigates electrochemical oxidation of m-cresol on boron-doped diamond electrode using direct current voltammetry (DCV), differential pulse voltametry (DPV) and cyclic voltammetry (CV). In aqueous media in pH range 2.0 - 12.0 m-cresol provides one oxidation peak. The electrode reaction is diffusion-controled. Because of electrode passivation two types of pretreatment were applied for reactivation of electrode surface., i.e. alumina polishing and anodic activation using potential of +2400 mV. Peak heights and potentials are strongly dipending on the type of pretreatment for DCV and DPV - the difference in peak potentials can reach 430 mV. Using optimal conditions for alumina polishing in 0.01 μmol·L-1 NaOH the linear dynamic range is 1.0 - 75 μmol·L-1 for DCV and 0.75 - 75 μmol·L-1 for DPV. And for anodic activation in BR buffer pH 2.0 the linear dynamic range is 0.75 - 75 μmol·L-1 for DCV and DPV. The influence of boron-doping level was investigated using a semiconductive and mettalic-type BDD film. For the latter the sensitivity in DP voltammetry is two times higer and for both types the linear dynamic range is ca 1 - 25 μmol·L-1 . The voltammetric response of m-cresol was further investigated in the presence of cationic surfactants. In the presence of CTAB and CPB the peak current...
The influence of the quality of articulation UHMWPE inserts on the lifetime of joint replacements
Fulín, Petr ; Pokorný, David (advisor) ; Koudela, Karel (referee) ; Gallo, Jiří (referee)
This thesis focuses on the introduction with the problems of high molecular weight polyethylene (UHMWPE) in orthopedics in the first part. It discusses the history, properties and processes that lead to the failure of UHMWPE joint replacement components. The experimental part validates the hypotheses expressed. It acquaints readers with the experimental verification of the effect of different types of sterilization on the oxidative stability of laboratory prepared samples and explanted UHMWPE joint replacement components using methods of infrared microscopy, electron spin resonance, mechanical tests and tests of microhardness. Other experimental measurements on a large set of explanted components of hip and knee total joint replacements validates the hypothesis that the amount of oxidative damage affects the lifespan of joint replacements. The third part of the experimental study maps the degree of oxidative damage in different places of the hip and knee joint replacements. In the final part we experimentally demonstrate the fact that the rate of oxidative damage has an effect on supramolecular structure of the UHMWPE. From the above experiments are concluded clearly defined recommendations for clinical practice, which should lead to extend the lifespan of total joints replacements in orthopaedics....
Utilization of carbon-based solid electrodes to electrochemical oxidation of acyclovir
Vaněčková, Eva ; Schwarzová, Karolina (advisor) ; Fischer, Jan (referee)
Electrochemical oxidation of acyclovir at glassy-carbone electrode and boron-doped diamond electrode gives one pH-dependent oxidation signal; the corresponding electrode reaction is controlled by diffusion. It is followed by a second indistinctive signal in the pH range 2,0 - 9,0. Further, optimization of conditions was carried out for determination of acyclovir using DC and DP voltammetry. The calibration dependence on GC electrode in B−R buffer (pH = 6,0) is linear only in the concentration range from 2 to 10 μmol∙l−1 for DCV with limit of detection 0,38 μmol∙l−1; for DPV it is not linear. BDD electrode has to be activated to prevent its passivation. Anodic activation at +2,4 V for 15 s with simultaneous stirring of solution results in relative standard deviation of 0,9% for acyclovir concentration of 1∙10−4 mol∙l−1. Using DCV and DPV methods linear concentration dependences were obtained in 0,1 mol∙l-1 nitric acid and in pH 6,0 B−R buffer. The lowest limit of detection and limit of quantification (LOD = 0,47 μmol∙l−1 a LOQ = 1,55 μmol∙l−1) and linear range from 0,6 to 100 μmol∙l−1 was reached in pH 6,0 B−R buffer. Further, standard addition method was used to quantify acyclovir in Zovirax tablets. Satisfactory recoveries of 101,1 ± 2,3 % using DCV and 98,8 ± 2,2 % using DPV at BDD (compared with the...
Voltammetric detection of stigmasterol at boron-doped diamond electrode in mixed media
Benešová, Lenka ; Schwarzová, Karolina (advisor) ; Nesměrák, Karel (referee)
V o l t a m m e t r i c d e t e c t i o n o f s t i g m a s t e r o l a t b o r o n d o p e d d i a m o n d e l e c t r o d e i n m i x e d m e d i a L e n k a B e n e š o v á Univerzita Karlova v Praze Přírodovědecká fakulta Praha 2015 Abstract The aims of the study thesis was to suggest suitable solvent for oxidation of stigmasterol on boron doped diamond electrode. Cyclic voltammetry in mixed media of water and organic solvents was used for this purpose. First of all, the effect of organic solvent on potential window of boron doped diamond electrode was studied. Solvents used were methanole, isopropanole, N-dimethylformamide and acetonitrile; the water components was phosphate buffer (0,075 mol.l-1, pH 3,0). It was deduced from the results, that suitable solvent for detection of stigmasterol on was the acetonitrile, which provided sufficiently large potential window in anodic area. Keywords: boron doped diamond electrode, cyclic voltammetry, organic solvent, oxidation, stigmasterol
Selective hydrogenation/Oxidation of CVD graphene using AFM
Přikryl, Vojtěch ; Švarc, Vojtěch (referee) ; Bartošík, Miroslav (advisor)
Graphene is a perspective material for utilization in electronics due to its high charge carrier mobility. However, in order to be applicable in practice the bandgap opening is necessary. One way of achieving this is modification of graphene by hydrogenation or oxidation. This work concerns the possibility of using AFM for local hydrogenation/oxidation of graphene depending on the bias voltage between the tip and the sample. The presence of hydrogenation/oxidation was examined by Kelvin probe force microscopy and Raman spectroscopy. The possibility of oxidation was proved but hydrogenation was not proved.
Biotransformation of phenols by enzymatic systems of Candida tropicalis yeast and Comamonas testosteroni bacteria
Vilímková, Lenka ; Stiborová, Marie (advisor) ; Entlicher, Gustav (referee) ; Mareš, Jaroslav (referee)
Candida tropicalis yeast and bacteria Comamonas testosteroni have been considered to be able to metabolize phenol and utilize it as the only source of carbon and energy. In our laboratory we investigated the cytoplasmic enzymes responsible for the first and second step of phenol degradation, NADPH-dependent phenol hydroxylase of both C. tropicalis and C. testosteroni and catechol 1,2-dioxygenase of C. tropicalis. The aim of our study was to isolate and partially characterize those enzymes. Phenol hydroxylase purification consisted of preparation of cytosol from C. tropicalis yeast by fraction centrifugation, chromatography and re-chromatography on a column of DEAE Sepharose, fractionation by precipitation of the enzyme with polyethylene glycol 6000 and gel permeation chromatography on a column of Sephacryl S-300. Extracellular phenol hydroxylase of C. testosteroni was purified by fraction precipitation with polyethylene glycol 6000 and by gel permeation chromatography on 4B Sepharose and Sephacryl S-300. Catechol 1,2-dioxygenase was purified using the procedure consisting of: chromatography and re- chromatography on a column of DEAE Sepharose, lyophilization of the enzyme and gel permeation chromatography on a column of Sephadex G-100. The enzyme activity was determined by two methods: use of HPLC...
Biochemical aspects of study and restoration of aged paintings
Hradilová, Iveta ; Hudeček, Jiří (advisor) ; Smrček, Stanislav (referee)
Every part of a work of art is changing in the course of time. Even simultaneously in its creation, when tempera or oil paint used dry up. Already this process can be considered as a biochemical change in the material. The main goal of a submitted bachelor's thesis is to compile recent knowledge about resins and protein media used in works of art, to describe their composition and, in particular to evaluate the changes they undergo in time after their application on canvas, wooden or metal surfaces and paper to their irrecoverable destruction. In addition, biological degradation of these substances by several species of bacteria, yeasts and fungi is discussed in the last part of this work. Key words: resins, terpenoids, protein media, degradation, oxidation, hydrolysis (In Czech)
Phosphinoferrocene conjugates of selected amino acids
Tauchman, Jiří ; Štěpnička, Petr (advisor) ; Růžička, Aleš (referee) ; Dvořák, Dalimil (referee)
A series of chiral phosphinoferrocene amides was prepared by the condensation either of 1'- (diphenylphosphino)ferrocene-1-carboxylic acid (Hdpf) or its planar-chiral 1,2-isomers and amino acid methyl esters in the presence of peptide coupling agents. The resulting phosphinoamides were tested as ligands in Cu-catalyzed asymmetric conjugate additions of diethylzinc to chalcones and in Pd-mediated asymmetric allylic substitution reactions of 1,3- diphenylallyl acetate with the respective nucleophile (alkylation, amination and etherification). The catalytic tests were focused on an optimization of the reaction parameters (solvent, temperature, base, metal/ligand ratio) and on survey of various substrates. Compounds based on Hdpf proved to be better ligands in both catalytic reactions than their planar chiral analogues. In order to rationalize the influence of the ligand structure on the reaction course and also to interpret the catalytic results, several model complexes were prepared and structurally characterized. Other three series of non-chiral complexes were prepared from the corresponding (η6 - arene)ruthenium(II) precursor and Hdpf-glycine conjugates; the neutral complexes of the type [(arene)RuCl2(Hdpf-Gly(R)-κP)] (arene = benzene, p-cymene, hexamethyl-benzene; R = OMe, NH2, OH) as well as two...

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