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1
Šik, Ondřej. „Studium šumových charakteristik detektorů radioaktivního záření“. Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-218099.
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The main goal of this Master’s thesis is to describe relationship between low frequency noise spectral characteristics of Cadmium-Telluride radiation detectors depending on applied voltage and detectors reaction to illumination of various wavelengths. Also, the reaction and influence of higher operating temperatures were investigated. The noise measurements shown that the dominant noise type at low frequencies is the 1/f noise. Several samples with different resistivity were tested. By comparing results, we are able to estimate the quality of detectors and their sensibility to illumination and higher operating temperatures. We have found that all the studied CdTe detectors are sensitive to one particular wavelength of 548nm. Resulting data were processed by EasyPlot program that provided graphical representation of spectral noise characteristics. All measured characteristics of tested samples are compared and it’s estimated the similarity between the samples.
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Bukvišová, Kristýna. „In-situ elektronová mikroskopie“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2019. http://www.nusl.cz/ntk/nusl-402571.
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Cílem diplomové práce je popsat oxidaci nanotrubic sulfidu wolframičitého za zvýšených teplot v přítomnosti vodní páry. Na jejich povrchu se nejprve vytvoří nanočástice oxidu wolframu, ze kterých potom vyrůstají nanodráty. Na základě in-situ experimentů v rastrovacím elektronovém mikroskopu je navržen mechanismus reakce a ten je zjednodušeně popsán analyticky. Ukazuje se, že elektronový svazek má zásadní vliv na reakci.
3
Těšík, Jan. „Luminiscence polovodičů studovaná rastrovací optickou mikroskopií v blízkém poli“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2017. http://www.nusl.cz/ntk/nusl-320110.
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This work is focused on the study of luminescence of atomic thin layers of transition metal chalkogenides (eg. MoS2). In the experimental part, the work deals with the preparation of atomic thin layers of semiconducting chalcogenides and the subsequent manufacturing of plasmonic interference structures around these layers. The illumination of the interference structure will create a standing plasmonic wave that will excite the photoluminescence of the semiconductor. Photoluminescence was studied both by far-field spectroscopy and near-field optical microscopy.
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Kuba, Jakub. „Studium fotoluminiscence tenkých vrstev MoS2“. Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-254284.
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The thesis deals with study of thin layers of transition metal dichalcogenides, especially of molybdenum disulfide. Nanostructures were fabricated on two-dimensional crystals of MoS2 and WSe2. Within followed analysis attention was paid to the photoluminescence properties. In the thesis transition metal dichalcogenides are reviewed and description of the modified process of preparation by micromechanical exfoliation is given.
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Šik, Ondřej. „Transportní, šumové a strukturální vlastnosti detektorů vysokoenergetického záření na bázi CdTe“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-261280.
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Poptávka ze strany vesmírného výzkumu, zdravotnictví a bezpečnostního průmyslu způsobila v posledních letech zvýšený zájem o vývoj materiálů pro detekci a zobrazování vysokoenergetického záření. CdTe a jeho slitina CdZnTe. jsou polovodiče umožnují detekci záření o energiích v rozsahu 10 keV až 500 keV. Šířka zakázaného pásma u CdTe / CdZnTe je 1.46 -1.6 eV, což umožňuje produkci krystalů o vysoké rezistivitě (10^10-10^11 cm), která je dostačující pro použití CdTe / CdZnTe při pokojové teplotě. V mé práci byly zkoumány detektory CdTe/CdZnTe v různých stádiích jejich poruchovosti. Byly použity velmi kvalitní spektroskopické detektory, materiál s nižší rezistivitou a výraznou polarizací, detektory s asymetrií elektrických parametrů kontaktů a teplotně degenerované vzorky. Z výsledků analýzy nízkofrekvenčního šumu je patrný obecný závěr, že zvýšená koncentrace defektů způsobí změnu povahy původně monotónního spektra typu 1/f na spektrum s výrazným vlivem generačně-rekombinačních procesů. Další výrazná vlastnost degenerovaných detektorů a detektorů nižší kvality je nárůst spektrální hustoty šumu typu 1/f se vzrůstajícím napájecím napětí se směrnicí výrazně vyšší než 2. Strukturální a chemické analýzy poukázaly, že teplotní generace detektorů způsobuje difuzi kovu použitého při kontaktování a stopových prvků hlouběji do objemu krystalu. Část mé práce je věnována modifikaci povrchu svazkem argonových iontů a jejímu vlivu na chemické složení a morfologii povrchu.
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Andreev, Alexey. „Šumová spektroskopie detektorů záření“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2008. http://www.nusl.cz/ntk/nusl-233425.
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Kadmium telurid je velmi důležitý materiál jak základního, tak i aplikovaného výzkumu. Je to dáno zejména jeho výhodnými elektronickými, optickými a strukturními vlastnostmi, které ho předurčují pro náročné technické aplikace. Dnes se hlavně používá pro jeho vysoké rozlišení k detekci a X-záření. Hlavní výhodou detektorů na bázi CdTe je, že nepotřebují chlazení a mohou spolehlivě fungovat i při pokojové teplotě. To způsobuje efektivnější interakce fotonů než je tomu u Si nebo jiných polovodičových materiálů. Obsahem této práce byla analýza a interpretace výsledků získaných studiem šumových a transportních charakteristik CdTe vzorků. Měření ukázaly že odpor homogenní části CdTe krystalů mírně klesá při připojení elektrického pole na vzorku. Při změně teploty navíc dochází k odlišné reakci u CdTe typu p a n. Právě těmto efektům je v práci věnována pozornost. Pomocí šumové spektroskopie bylo zjištěno, že při nízkých frekvencích je u vzorků dominantní šum typu 1/f, zatímco při vyšších frekvencích je sledován generačně-rekombinační šum a tepelný šum. Všechny měřené vzorky vykazovaly mnohem vyšší hodnotu šumu na nízkých frekvencích než udává Hoogeova rovnice. Byly nalezeny a popsány zdroje nadbytečného šumu.
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Zajaček, Jiří. „Šumová spektroskopie detektorů záření na bázi CdTe“. Doctoral thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2009. http://www.nusl.cz/ntk/nusl-233498.
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The main object of this work is noise spectroscopy of CdTe radiation detectors (-rays and X–rays) and CdTe samples. The study of stochastic phenomenon and tracing redundant low-frequency noise in semiconductor materials require long-term measurements in time domain and evaluate suitable power spectral densities (PSD) with logarithmic divided frequency axes. We have used the means of time-frequency analysis derived from the discrete wavelet transform (DWT) and we have designed the effective algorithm for PSD estimation, which is comparable with an original analog method. CdTe single crystal with Au contacts we can imagine as a series connection of two Schottky diodes with a resistor between them. The bulk resistance at constant temperature and other constant parameters changes due to the carrier concentration changing only. The p-type CdTe sample shows metal behavior with every temperature changes. Semiconductor properties of the sample begin to dominate just after some period of time. This behavior is caused by the hole mobility changing. The voltage noise spectral density of 1/f noise depends on the quantity of free carriers in the sample. All the studied samples have very high value of low frequency noise, much higher than it should have been according to Hooge’s formula. The excess value of low frequency noise is caused by the low carrier concentration within the depleted region.
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Pelnářová, Karolína. „Hledání účinných chelátorů kobaltu - 8-hydroxychinoliny“. Master's thesis, 2021. http://www.nusl.cz/ntk/nusl-445817.
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Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology & Toxicology Student: Karolína Pelnářová Supervisor: Prof. Přemysl Mladěnka, PharmD., Ph.D. Consultant: Václav Tvrdý, MSc.; Marcel Hrubša, MSc. Title of diploma thesis: Searching of effective cobalt chelators - 8-hydroxyquinolines Cobalt is one of the essential trace elements present in the human body. It forms a part of the organometallic complex of vitamin B12, which is essential for many physiological functions. Both overload and lack of cobalt in the body is associated with pathological conditions. Manifestations of deficiency can lead up to pernicious anemia or hypofunction of the thyroid gland. Cobalt intoxication can occur in an industrial environment, such as by cobalt metal dust during heavy metal processing, or by its release due to corrosion from orthopedic prostheses. Systemic toxicity is manifested by a number of endocrine, cardiovascular and neurological symptoms. The main aim of this diploma thesis was to find effective chelators of cobalt from the group of substances derived from 8-hydroxyquinoline. In vitro spectrophotometric measurement was used to determine the degree of chelation. The effect of chelation was also monitored ex vivo in rat erythrocytes. All tested chelators - 8-hydroxyquinoline,...
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Řezníčková, Alice. „Nanostruktury magnetoresponsivních oxidů přechodných kovů“. Doctoral thesis, 2017. http://www.nusl.cz/ntk/nusl-370892.
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The thesis is focused on investigation of structural and magnetic properties of nanocomposites consisting of transition-oxide-based nanoparticles (NPs; CoFe2O4 and Fe2O3) embedded in dielectric matrices (SiO2, CeO2, TiO2, ZrO2, Al2O3). The nanocomposites were studied by broad range of complementary techniques (X-ray diffraction, electron microscopy, energy dispersive x-ray analysis, Mössbauer Spectroscopy and Magnetic measurements). Among them, analysis of the distributions of the NP magnetic moments and blocking temperatures was identified as a powerful tool for characterization of NP changes due to mutual interactions, surface modifications and embedding into the functional matrices. The effect of structural and spin order of the individual NPs on the volume magnetic response is also addressed. The obtained results imply new strategies for design of efficient heat nanogenerators and catalysts.
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Beliš, Marek. „Selektivní komplexace iontů přechodných kovů“. Master's thesis, 2017. http://www.nusl.cz/ntk/nusl-365329.
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Copper radionuclides possess physical properties suitable for utilization in nuclear medicine. Important part of their preparation is separation from mother elements, usually zinc or nickel. Currently used methods of separation have their limits, what opens field for finding new ways. One part of the Thesis contains preparation of simple ion exchangers and their selectivity study. The other part of the Thesis is dedicated to optimization of synthetic steps leading to new bifunctional ligands in suitable form for binding to macromolecular carriers and preparation of new set of exchangers.
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Faberová, Jana. „Interakce chalkonů s přechodnými kovy I“. Master's thesis, 2021. http://www.nusl.cz/ntk/nusl-446104.
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Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany Candidat: Jana Faberová Supervisor: doc. Ing. Kateřina Macáková, Ph.D. Title of Thesis: Interaction of chalcones with transition metals I. Iron is a biogenic metal element with unpaired d-electrons that plays a key role in the survival of unicellular organisms, plants and mammals. The electron shell of the iron atom is able to easily bind and release electrons and thus contribute to the proper function of the organism. Iron is necessary to ensure the transport of respiratory gases, cell differentiation and the functioning of some specific enzymes. However, despite the clearly positive effect of iron on human health, inappropriately low or high level of iron in the body can cause the development many diseases. Chalcones are plant polyphenols belonging to the family of flavonoids, secondary metabolites of plants. The term chalcone generally refers to a chemical structure with an ,-unsaturated ketone system based on 1,3-diphenylprop-2-en-1-on. These substances have a wide spectrum of biological activities and in the right amount can be good for human health. The aim of this diploma thesis was to monitor the iron-chelating and iron-reducting activity of selected chalcones: isoliquiritigenin, licochalcon A,...
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Šulcová, Martina. „Interakce chalkonů s přechodnými kovy II“. Master's thesis, 2021. http://www.nusl.cz/ntk/nusl-446252.
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Charles University in Prague Faculty of Phramacy in Hradec Králové Department of Pharmaceutical Botany Candidate: Martina Šulcová Supervisor: Assoc. Prof. Ing. Kateřina Macáková, Ph.D. Title of the diploma thesis: Interaction of chalcones with transition metals II. Copper is one of the essencial elements in human body which is involved in the functioning of many enzymes and metabolic pathways. Although it appears in trace amounts in the body, its functions are irreplaceable. However, the ion level must be kept in balance by the various mechanisms of the body. If there is an excess or deficiency of copper in the body, this condition can lead to the development of health issues. Chalcones are substances belonging to the group of flavonoids. Their polyphenolic structure does not have a closed ring C. Studies describe their anticancer, anti-inflammatory, antiviral, antidiabetic, antibacterial, antioxidant, immunosuppressive and other properties. Chosen substances in the group of dihydrochalcones (naringin dihydrochalcone, neohesperidin dihydrochalcone, phloretin, phlorizin) and chalcones (isoliquiritigenin, licochalcone A) were tested for their chelation and reduction activity of the copper ions in this diploma thesis. The activity was measured at different pH environments (7.5; 6.8; 5.5 and 4.5) and...
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Šilhová, Markéta. „Interakce alkaloidů s přechodnými kovy II“. Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-405336.
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Charles University, Faculty of Pharmacy in Hradec Králové Department of: Pharmaceutical Botany Consultant: Ing. Kateřina Macáková, Ph. D. Student: Markéta Šilhová Title of Thesis: Interactions of alkaloids with transition metals II. Copper is an important component of the human body. It is involved in the right functioning of organ systems and is also a part of many important body enzymes. It is necessary to maintain a balanced amount of copper in the body in order to avoid excess or deficiency, which can lead to various diseases. The aim of this diploma thesis was to determine the copper chelating and copper reducing effects of isoquinoline alkaloids berberine chloride, canadine, corydaline, sculerine, sinactine, stylopine, tetrahydropalmatine, allocryptopine, protopine, corycavamine and cryptopine. In experimental measurements the determination of chelation of copper ions with hemytoxyline and the determination of chelation and reduction of copper ions using disodium salt of bathocuproindisulfonic acid was performed. The highest reducing activity was exhibited by scoulerine, whose structure in comparison with other alkaloids contains hydroxyl groups and which has been exhibited in the past to inhibit the growth of tumour cell. The lowest reducing activity was measured for protopine alkaloids and...
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Rzepecká, Radka. „Interakce alkaloidů s přechodnými kovy I“. Master's thesis, 2019. http://www.nusl.cz/ntk/nusl-405499.
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Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany Candidate: Radka Rzepecká Supervisor: Ing. Kateřina Macáková, Ph.D. Title of Thesis: Interactions of alkaloids with transition metals I. Copper is one of the essential trace elements that are necessary for the proper functioning of the organism. Copper is a significant component of many enzymes that affect various metabolic processes in the human body. It is important that the level of copper in the body is regulated because its deficit or excess lead to a variety of pathological conditions. Alkaloids are secondary plant metabolites that are distinguished by numerous biological activities. In this thesis the copper-chelating and copper-reducing activity of eleven isoquinoline alkaloids was measured: boldine, isocorydine, (+)-bulbocapnine, (+)-corydine, glaucine, (-)-sinoacutine, (-)-californidine, (-)-escholtzine, platycerine, (-)-fumaricine, and (+)- parfumine. Alkaloid activity was measured at four (patho) physiological pH values by a verified spectrophotometric method using two indicators: bathocuproinedisulfonic acid disodium salt and hematoxylin. Based on the results, structure-effect relationships were derived. The results show that none of the tested substances was able to chelate copper ions. In...
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Loskotová, Lenka. „Interakce alkaloidů s přechodnými kovy IV“. Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-412235.
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Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Botany Candidate: Bc. Lenka Loskotová Supervisor: doc. Ing. Kateřina Macáková, Ph.D. Title of Thesis: Interactions of alkaloids with transition metals IV. Copper is a biogenic trace element that participates in the proper function of an organism. It is part of a number of enzymes and participates in metabolic processes in the human body. The level of copper in the organism should be regulated to avoid its excess or deficit, as pathologies could occur. Alkaloids are natural nitrogenous substances of alkaline nature. We find many biological activities in them. The aim of this thesis was to measure copper-chelating and copper- reducing activity of isoquinoline alkaloids: corypalmine, thalictricavine, 8-oxoberberine, fumarilin, norisocorydine and laurotetanine. Alkaloid activity was measured at different pH environments (4.5; 5.5; 6.8 and 7.5) and in the DMSO environment by a spectrophotometric method using hematoxyline and acid disodium salt bathocuproindisulfonic. Based on the results, structure-effect relationships were derived. In experimental measurement, it was found that none of us tested alkaloids showed chelating activity. Reduction activity has been demonstrated in all test substances. The lowest activity...
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Cymbál, Martin. „Interakce alkaloidů s přechodnými kovy III“. Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-412276.
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Charles University Pharmaceutical Faculty in Hradec Králové Department of Pharmaceutical Botany Candidate: Bc. Martin Cymbál, DiS. Supervisor: doc. Ing. Kateřina Macáková, Ph.D. Diploma thesis 2019/2020: Interactions of alkaloids with transition metals III., pp. 86. Copper is one of the important trace elements in the body. It regulates various enzymatic pathways. This work monitors the chelating and reducing activity of isochinoline alkaloids of the family Amaryllidaceae. The alkaloids of Amaryllidaceae have a large number of effects such as analgesic, narcotic, antiarrhythmic, antihypertensive, bronchodilatory, chemotherapeutic, antiparasitic, uteretonic, locally anesthetic, mydriatic and many other significant effects. An important representative is galanthamine hydrobromide, which is therapeutically used and is an inhibitor of acetylcholinesterase. Galanthamine type alkaloids (galanthamine, galanthamine hydrobromide, chlidanthine), lycorine type (lycorine, galanthine), haemanthamine type (haemanthnamine, vittatine) and montanine type (montanine) were studied. The methodology of the work was to determine the chelating and reducing activity with the use of the hematoxylin indicator and bathocuproindisulfonic acid, at different pH or in dimethylsulfoxide. Of the alkaloids studied, galanthamine and...
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Mantlíková, Alice. „Struktura a magnetismus nanočástic na bázi přechodných kovů“. Master's thesis, 2011. http://www.nusl.cz/ntk/nusl-300444.
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The aim of the work is characterization of structure and magnetic properties of various CoFe2O4/SiO2 nanocomposites. Emphasis was put on the corelation of the magnetic properties with particle size (samples with different annealing temperature) and with strenght of the interparticle interactions (samples with different Fe/Si ratio or without silica matrix). Structure properties of all samples were determinated by powder x-ray diffraction, scanning and transmission electron microscopy. Magnetic properties were determinated by standard (temperature dependence of magnetization, magnetization isotherms) and advanced (a.c. susceptibility, memory effects) magnetic measurements. A sharp increase of the values of blocking temperature and coercivity with increase of strenght of the interparticle interactions and with increase of particle size was observed. Particle size determines the maximum value of coercivity and blocking temperature and strengh of the interparticle interactions shift this values in the interval determined by particle size.
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Hyklová, Barbora. „Vrstevnaté hydroxidy přechodných kovů, jejich delaminace a vlastnosti“. Doctoral thesis, 2018. http://www.nusl.cz/ntk/nusl-373938.
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Charles University Faculty of Science Study programme: Inorganic Chemistry Mgr. Barbora Hyklová Layered Transition Metal Hydroxides: Delamination and Properties Extended abstract Supervisor: Ing. Kamil Lang CSc., DSc. Supervisor-Consultant: RNDr. Jan Demel PhD. Prague, 2017 Layered transition-metal hydroxides have attracted increasing attention as promising active electrode materials for electrochemical energy storage and conversion device due to facile preparation and modification, good tunability, high capacitance capability, fast reversible redox reactions, and cost effectiveness. Many reported hierarchical architectures based on nickel and cobalt hydroxides are composed of bulky nanoplatelet-like aggregates; however, the nanomorphology and behavior of the separated hydroxide nanosheets is much less known. Figure 1. Scheme of layered nickel or cobalt hydroxide delamination and subsequent restacking on conductive HOPG support. In this respect, the dissertation thesis reports characterization and electrochemical performance of nickel, nickel-cobalt, and cobalt hydroxide nanosheets, synthesized by an economical and environmentally friendly method based on delamination of corresponding layered hydroxides in water (Figure 1). For this purpose, lactate and nitrate layered hydroxides were prepared by two...
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Matoušek, Mikuláš. „Výpočty elektronové struktury biologicky relevantních komplexů přechodných kovů“. Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-415411.
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Porphyrins are an important class of biomolecules, which are heavily studied, both ex- perimentally and computationally. But, despite the intensive efforts, for many questions we still aren't able to consistently find an agreement between theory and experiment. One of the still unresolved issues is the character of the ground state of the Fe(II)-porphyrin molecule. We used a model of the Fe(II)-porphyrin molecule to study the effects of geometrical changes on the spin states. By carrying out extensive DMRG-CASSCF cal- culations topped with TCCSD correlation treatment we are able to link the effects of these geometrical changes to the experimental results, and predict a quintet ground state for the isolated Fe(II)-porphyrin molecule. Also, using a ligated porphyrin belonging to the iron porphyrin carbene class of molecules, we demonstrate by combining the CASSCF and AC0 methods that geometrical changes outside the porphyrin core cannot be over- looked. 1
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Nečas, David. „Reakce alkenů vyvolané hydridy a alkyly přechodných kovů“. Doctoral thesis, 2009. http://www.nusl.cz/ntk/nusl-278406.
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l0 5. Conclusion 1) The first and practical catalýic method for smooth deallylation of 2-substituted-2-allylmalonates to 2-substituted malonates via selective cleavage of the C-C bond under mild reaction conditions has been developed' The reaction seems to be general with respect to the transition-metal complexes; however, the comparison of Ru and Ni catalysts indicates considerable differences in their specific activity and selectiviý. Last but not least, the smooth deallylation offers an opportuniý to use the allyl group as an effective protective group for acidic hydrogen of malonic esters. 2) It has been shown that it is possible to re-route the course of the reaction from c{ bond cleavage (deallylation) to c{ bond formation (cyclization) in Ni hydride cataryzed, reactions by a change in the amount of organoaluminium. It proceeded in high yields even in cases where deallylation could compete with cyclization (e.g. diallylmalonate, etc.) in high selectiviý. In addition, generation of Ni hydride species in sinr provides an effective means for fast and selective cyclization of variously substituted 1,6- heptadienes to cyclopentanes. Moreover, it is possible exert certain level of control for the preferential formation of methylidene(methyl)cyclopentanes or cyclopentenes by the appropriate choice of thb...
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Žádný, Jaroslav. „Příprava a využití komplexů přechodných kovů s helikálními ligandy“. Doctoral thesis, 2015. http://www.nusl.cz/ntk/nusl-333755.
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The Thesis describes our successful endeavour to develop asymmetric synthesis of functionalized 2H-pyran or 2,7-dihydrooxepine helicene-like compounds in an optically pure form. These helicene surrogates were fully characterized and their use in enantioselective catalysis as chiral ligands, organocatalysts or chiral modifiers was explored. A general method for the preparation of optically pure [5]- and [6]heterohelicenes by asymmetric synthesis is based on highly diastereoselective [2+2+2] cycloisomerization of centrally chiral triynes mediated/catalyzed by transition metal complexes. Stereochemical outcome of the cyclization process is controlled by 1,3-allylic-type strain. This new methodology is highly versatile providing an easy access to chiral ligands, organocatalysts or modifiers in a nonracemic form. Optically pure 2,7-dihydrooxepine [5]helicene-like phosphite ligands were explored in enantioselective allylic amination under catalysis by iridium(I) complexes to reach up to 82% ee. An organocatalysts represented by the optically pure 2H-pyran [5]helicene-like DMAP analogue was synthesized and applied to kinetic resolution of racemic sulfoximines. Finally, various functionalized derivatives of helicenes and helicene-like compounds (azahelicenes, DMAP analogues, (thio)urea derivatives) were...
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Novák, Petr. „Využití reakcí katalyzovaných komplexy přechodných kovů v syntéze biologicky aktivních sloučenin“. Doctoral thesis, 2008. http://www.nusl.cz/ntk/nusl-290741.
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Kobrlová, Andrea. „Využití bezmembránové elektrolytické cely pro elektrochemické generování těkavých specií přechodných kovů“. Master's thesis, 2013. http://www.nusl.cz/ntk/nusl-324638.
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This diploma thesis is focused on the study of electrochemical generation volatile species of gold and silver. Two non-membrane electrolytic cells were constructed for electrochemical generation volatile species. These cells differ in the volume of electrode chamber. An atomic absorption spectrometry with quartz tube atomizer was used in most experiments. The equipment was performed in flow continuous mode. Experiments confirmed, that it is possible to use an atomic absorption spectrometry with quartz tube atomizer for generate volatile species of gold and silver by using two non-membrane electrolytic cells. The main part of this thesis was to find optimal conditions for the electrochemical generation of volatile species of gold and silver. These optimized parameters were: the cathode material, the type of electrolyte, the flow rate of the carrier gas, the generation current and the electrolyte flow rate. The calibration curves for both analytes were measured for both non-membrane electrolytic cells and the basic characteristics of the measurement were observed. Detection limit for electrochemical generation of gold was 1,61mg dm 3 and repeatability 3,93 %, detection limit for electrochemical generation of silver was 0,20 mg dm 3 and repeatability 7,33 %. Thanks to the experiments with a...
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Hurný, David. „Syntéza cyklických sloučenin za využití organokatalýzy a katalýzy komplexy přechodných kovů“. Master's thesis, 2014. http://www.nusl.cz/ntk/nusl-339206.
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This thesis deals with an enantioselective synthesis of cyclic compounds by using a combination of organocatalysis and transition metal catalysis. The thesis deals mainly with usage of aminocatalyst for activation of aldehydes and copper catalyst for activation of terminal triple bond. The first part is focused on the preparation of starting compounds for cyclizations (α-oxoesters, α- substituted nitroalkanes and α-substituted aldehydes). The second part concerns carbocyclization itself and optimization of reaction conditions to achieve highly stereoselective reaction. Powered by TCPDF (www.tcpdf.org)
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Prchalová, Eva. „Využití reakcí zprostředkovaných přechodnými kovy v syntéze biologicky aktivních derivátů estronu“. Doctoral thesis, 2016. http://www.nusl.cz/ntk/nusl-352036.
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This thesis relates to the preparation and use of new non-estrogenic ligands selective for certain types of the 17β-hydroxysteroid dehydrogenase superfamily (17βHSD). Such nonestrogenic compounds, which selectively regulate the activity of 17βHSD are believed to offer new solutions in endocrine therapy, diagnosis and treatment of estrogen-dependent types of diseases. In recent years in the laboratories of my supervisor prof. Kotora differently substituted steroid derivatives with interesting biological properties were prepared. Based on the gained experiences, it was decided to prepare C-15 estrone derivatives. Such compounds are mostly unexplored, and therefore they might be a new class of interesting biologically active compounds. A method was developed for the preparation of C-15 estrone derivatives. Estrone, the starting material for the synthesis, was first converted to the appropriate intermediate, protected estra-1,3,5(10),15-tetraene-17-one. Conjugate addition of vinylmagnesium bromide to this enone yielded the starting material for further reactions, 15β-vinylestrone. Cross metathesis of 15β-vinylestrone with suitable terminal olefins provided large series of C-15 estrone derivatives with perfluoroalkylated, aliphatic and aromatic side chains. Selected unsaturated derivatives were tested...
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Plášil, Jakub. „Krystalochemie vybraných přírodních arseničnanů a fosforečnanů uranylu dvojmocných přechodných kovů a hořčíku“. Master's thesis, 2009. http://www.nusl.cz/ntk/nusl-281667.
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Jagtap, Pratap Ramling. „Propojení organokových činidel, katalýzy přechodnými kovy, radikálových a karbokationických procesů v dominových reakcích“. Doctoral thesis, 2017. http://www.nusl.cz/ntk/nusl-267012.
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This work deals with the development of methodology, which couples reactive intermediates of varying oxidation states, in tandem sequences comprising 1,2-organometallic addition/transition metal catalyzed isomerization/Michael addition/SET oxidation/radical cyclization/oxygenation steps in the synthesis of highly functionalized carbocycles. Implementation of this sequence being catalytic in the SET oxidant was studied. 1,4-Diketones were synthesized in a tandem 1,2-addition/ruthenium-catalyzed redox isomerization/enolates oxidation/radical dimerization reaction and results were compared with 1,4-diketones formation via oxidative coupling of ketone enolates. The total synthesis of selective tetrahydrofuran lignans from 1,4-diketones obtained in a tandem addition/isomerization/dimerization reaction is also documented
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Srnec, Martin. „Katalytické a elektronové vlastnosti "redox-aktivních" metaloproteinů a komplexů přechodných kovů z pohledu výpočetní chemie“. Doctoral thesis, 2010. http://www.nusl.cz/ntk/nusl-295443.
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Charles University in Prague Faculty of Science Department of Modeling of Chemical Properties of Bio- and Nanostructures Catalytic and Electronic Properties of Redox-Active Metalloenzymes and Transition- Metal Complexes: Insights from the Computational Chemistry Dissertation Thesis Abstract RNDr. Martin Srnec Supervisor: Mgr. Lubomír Rulíšek, CSc. Institute of Organic Chemistry and Biochemistry AS CR Center for Biomolecules and Complex Molecular Systems Praha 2010 Introduction Metals and their ions play a key role in maintaining life. They frequently promote protein folding, the stabilization of protein scaffolds, enzymatic activity, energy conversion, intra- and intercellular signals etc. Several decades ago, metalloproteins were considered as a rather small group of proteins. Nowadays, one-third of enzymes are estimated to contain one or more metal ions, whose presence is crucial for their enzymatic functionality. Metalloenzymes participate most often in the catalysis of difficult chemical reactions (e.g. the hydroxylation of methane, decomposition of H2 into protons and electrons, N2 and O2 bond cleavage and many other examples), in oxidation-reduction and electron-transfer reactions, and in the catalysis of spin-forbidden reactions, where relativistic effects (i.e. spin-orbit coupling) are necessary....
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Šálová, Tereza. „[2+2+2] Cykloadiční reakce katalyzovaná komplexy přechodných kovů jako robustní nástroj syntézy derivátů pyridinu“. Master's thesis, 2008. http://www.nusl.cz/ntk/nusl-290772.
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Malová, Zuzana. „Koordinační chemie farmak“. Master's thesis, 2020. http://www.nusl.cz/ntk/nusl-435947.
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Present methods for diagnosis of neurodegenerative diseases are rather limited and in clinical practise are missing. This thesis is focused on utilization of the positron emission tomography using isotope 64 Cu(II). For the project, two contrast agents were proposed containing ligand for Cu (II) coordination and thioflavine T derivative as fluorescent dye, also as a targeting compound. Structure of the thioflavine T derivative was defined by X-ray structural analysis. The selected fluorescent dye has a high affinity for incipient amyloids and, when bound to their structure, has enhanced fluorescent properties. The proposed ligands are tetraazacyclic. The first one is a diamide, where the thioflavin T derivative is part of a macrocyclic ring. The second selected ligand is linked to the thioflavin T derivative via a linker. Key words: complexes; pharmaceuticals; transition metals
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Antunes, Corrêa Cinthia. „Strukturní analýza vybraných silicidů přechodných kovů pomocí rentgenové difrakce a dynamického upřesňování dat z elektronové difrakce“. Doctoral thesis, 2017. http://www.nusl.cz/ntk/nusl-369550.
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Title: Structure analysis of some transition metal silicides using X-ray diffraction and dynamical refinement against electron diffraction data Author: Cinthia Antunes Corrˆea Department: Physics of Materials Supervisor: prof. RNDr. Miloš Janeček, CSc., Department of Physics of Materials Abstract: This thesis presents the crystal structure analysis of several transition metal silicides. The crystal structures were studied primarily by precession electron diffraction tomography (PEDT) employing the dynamical refinement, a method recently developed for accurate crystal structure refinement of electron diffraction data. The optimal values of the parameters of the method were proposed based on the comparison between the dynamical refinement of PEDT data and a high- quality reference structure. We present the results of the comparison using a Ni2Si nanowire with the diameter of 15 nm. The average atomic distance between the model obtained by the dynamical refinement on PEDT data and the one by single crystal X-ray diffraction was 0.006 ˚A. Knowing the accuracy and limitations of the method, the crystal structure of Ni3Si2 was redetermined on a nanowire with 35 nm of diameter. The model obtained had an average error in the atomic posi- tions of 0.006 ˚A. These results show that the accuracy achieved by the dynamical...
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Pelcová, Pavlína 1978. „Stanovení přechodných kovů v biologických materiálech metodami atomové spektrometrie :stanovení chemických forem rtuti v biologických materiálech /“. Doctoral thesis, 2005. http://www.nusl.cz/ntk/nusl-92731.
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Kucharčíková, Vendula. „Comparison of manual and dynamic extractions of selected transition metals from solid samples“. Master's thesis, 2016. http://www.nusl.cz/ntk/nusl-350277.
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Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Analytical Chemistry Candidate: Vendula Kucharčíková Supervisor: Burkhard Horstkotte, Ph.D. Consultant: Doc. PharmDr. Hana Sklenářová, Ph.D. Title of thesis: Comparison of manual and dynamic extractions of selected transition metals from solid samples The analysis of trace metals in soil is a subject of study in many laboratories. Due to large industrial areas soil can be highly contaminated. This work focused on two easy methods - manual extraction and single flow extraction with the same extractant -acetic acid. Two methods, two concentrations of acetic acid (0.11 M and 0.43 M), and two samples were used to evaluate, which conditions were more effective. As a detection device inductively coupled plasma - optical emission spectrometry was selected and two different wavelengths were used to prevent interferences. Manual extraction was more time-consuming and less reproducible than the dynamic extraction. Higher concentration of acetic acid extracted a larger amount of metals and the extraction showed higher reproducibility of the results. In both soils the contaminations with Cu outreached the permitted level for this metal (according to the requirement of the government of the Balearic Islands) and are potentially...
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Gorbunov, Denis. „Magnetické a magnetoelastické vlastnosti f-d intermetalik s vysokým obsahem 3d kovů“. Doctoral thesis, 2014. http://www.nusl.cz/ntk/nusl-332311.
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Fundamental magnetic properties have been studied in RFexAl12-x (R - heavy rare-earth element) compounds with the tetragonal crystal structure of the ThMn12 type. In the homogeneity range 4 ≤ x ≤ 6, exchange interactions and magnetocrystalline anisotropy of the Fe sublattice are significantly modified as found in LuFexAl12-x with non-magnetic Lu. With increasing Fe content, antiferromagnetic exchange interactions weaken and ferromagnetic strengthen. The change of the type of magnetic ordering occurs in the vicinity of x = 5. The Fe sublattice displays an easy-plane magnetic anisotropy that weakens with growing Fe concentration. RFe5Al7 compounds with magnetic R are highly anisotropic ferrimagnets with Curie temperatures from 193 to 262 K. Spontaneous and field-induced magnetic phase transitions of anisotropic and exchange nature have been found in RFe5Al7 by measurements of magnetization and sound propagation. The transitions provide quantitative information on the R-Fe inter-sublattice exchange. A correlation between the R element and the fundamental magnetic properties has been found for RFe5Al7. The Fe magnetic moment is near 8 µB per formula unit. The compounds with R - Tb, Dy, Ho and Er have a compensation of the rare- earth and iron sublattice magnetizations. The compensation point and Curie...
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Brajer, Martin. „Laserová spektroskopie materiálů pro spintroniku“. Master's thesis, 2015. http://www.nusl.cz/ntk/nusl-331777.
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In these diploma thesis magnetically ordered materials are studied with the prospect of their application in spintronics. Specifically, we investigated metallic alloy FeRh, which undergoes a magnetic phase transition from antife- romagnetic phase to feromagnetic one around 100◦ C. This phenomenon can be readily used in memory devices. Laser spectroscopy is used as a nondestructive method without need of any electrical contacts. Magnetic properties of FeRh are studied by magnetooptical effects including quadratic magnetic linear dichroism. The measured polarization rotations are of the order of miliradians, therefore, the detection is realized by an optical bridge. At first, we concentrated on discrimina- ting of various magnetooptical effects from each other. The second part is focused on the phase transition induced by different means. Firstly, by heating the whole sample, secondly by illuminating the sample locally by continuous laser.
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Obuch, Jakub. „Příprava nesymetrických derivátů DOTA a studium jejich komplexů“. Master's thesis, 2021. http://www.nusl.cz/ntk/nusl-449091.
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Lanthanide(III) complexes are compounds with both diagnostic and therapeutic applications. For diagnostic applications, they are used as contrast agents for imaging techniques such as MRI, PET or SPECT. In therapy, complexes of beta or alpha particle- emitting radionuclides are used. If the complexes contain protonable groups, their behaviour is dependent on pH of the solution. Protonation of these groups should occur close to the physiological pH. If the efficiency (relaxivity) of the MRI contrast agent is dependent on protonation state, this method can be used for determination of pH of tissues in vivo. For radiopharmaceuticals, fast complexation of short-lived metal radionuclides is important and protonation might significantly accelerate the complex formation. For therapeutic applications, possibility of labelling at low temperatures when heat-sensitive biovectors (e.g. antibodies) do not decompose. To assess the effect of protonation of amino group in the vicinity of the metal ion, amino-bis(phosphinate) pendant arm was proposed, where the dissociation constant of the amino group below the physiological pH can be expected. Three ligands containing this group and DO3A fragment were prepared and their complexes were studied to assess aforementioned possible uses in medicine. Their structure and...
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Pacáková, Hana. „Chemické a environmentální vzdělávání na střední škole - téma: Suroviny a jejich využití“. Master's thesis, 2010. http://www.nusl.cz/ntk/nusl-284886.
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Topics Raw materials and their utilisition has been disposed in this graduation thesis. A survey of curicular documents, school books for secondary schools and theses focused on D-elements has been conducted. The technical text transformation into the teaching material has been made on the basis of this survey. This can be used as teaching aids in chemistry and environmental lessons. Experiments suitable for secondary teaching have been carried and the lab protocol for the higher and lower grades of grammar schools has been created.
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Špánek, Jiří. „Koordinační sloučeniny jako kontrastní látky pro 19F MRI“. Master's thesis, 2018. http://www.nusl.cz/ntk/nusl-388728.
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Magnetic Resonance Imaging (MRI) is one of noninvasive imaging and diagnostic methods in today's medicine. The most commonly measured nucleus is H1 of the water molecules present in the human body. There are also methods that use signal saturation transfer between the contrast agent and water molecules via exchangeable H1 nuclei, or use a different nucleus like F19 . Compounds that show a high potential in this area are complexes of paramagnetic ions such as Gd3+ , Eu3+ , Co2+ , Cu2+ and Ni2+ , which can affect relaxation times and chemical shifts of other atoms due to their magnetic properties. This Master's thesis focuses on ligands L1 and L2 which were prepared in the Bachelor thesis. The main focus is on preparation of complexes with selected paramagnetic ions and subsequent study of their properties relevant for a potential use as contrast agents for F19 -MRI and CEST methods. Keywords: F19 -MRI, CEST, macrocyclic ligands, coordination chemistry
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Krchová, Tereza. „Responzivní kontrastní látky pro tomografii magnetické rezonance (MRI)“. Doctoral thesis, 2017. http://www.nusl.cz/ntk/nusl-357606.
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ABSTRACT This work is focused on the synthesis of a family of new macrocyclic ligands with exchangeable protons on coordinating groups that could potentially serve (after complexation with suitable paramagnetic lanthanide(III) ions) as responsive contrast agents (CAs) for magnetic resonance imaging (MRI). It is expected that measurement of extracellular pH should bring information for tumorous disease diagnoses and/or for suggesting the most efficient treatment. Therefore, our attention was focused on pH-dependent CAs based on a PARAmagnetic Chemical Exchange Saturation Transfer (PARACEST) mechanism capable of reporting pH changes in tissue. The PARACEST-related properties of a series of Ln(III) complexes with the CEST effect caused by amino groups coordinated to the central Ln(III) metal ions were investigated. Such a kind of PARACEST CA is new and has had no precedent in the literature. It was shown that these Ln(III) complexes produce a pH-sensitive PARACEST effect in the pH region relevant for living systems. The study brings proof-of-principle for utilization of complexes with a linear diamine pendant arm, i.e. complexes with two exchanging proton pools, for ratiometric pH determination by MRI independently on the probe concentration. In addition, to ensure a higher kinetic inertness of the...
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Hraníček, Jakub. „Konstrukce miniaturních průtokových cel pro elektrochemické generování těkavých sloučenin“. Doctoral thesis, 2011. http://www.nusl.cz/ntk/nusl-312116.
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(EN) The presented dissertation thesis summarizes the new results of electrochemical generation of volatile compounds usable in atomic spectral methods. The main aim of this work is to develop and to characterize new types of electrolytic flow-through cells and to examine their possibilities of determination of arsenic, selenium and antimony by using the electrochemical hydride generation technique coupled with atomic absorption spectrometry with a quartz tube atomizer. Individual electrolytic cells were designed and constructed to comply with two important requirements. The cathode chamber of the electrolytic cell should have a minimal volume and a high efficiency of analyte conversion to the volatile hydride. Constructed electrolytic cells are divided into the construction groups and described in the experimental part. Selenium was chosen as the first analyte. The relevant working parameters (such as type, concentration and flow rate of electrolytes, generation current and carrier gas flow rate) were optimized for each newly constructed electrolytic cell. Under the optimal working parameters, the basic characteristics of selenium determination were found out by using electrochemical hydride generation. The electrolytic cells were compared to each other and with the classical electrolytic cell...