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Chirality and its importance in environmental organic analysis
Svobodová, Dagmar ; Friedl, Zdeněk (referee) ; Čáslavský, Josef (advisor)
This bachelor thesis is elaborated as literature search focused on the characterization of chirality and its importance for the environment. This work also gives review of the analytical methods and procedures aplicable for the chiral analysis of the organic pollutants. Obtained information showed that the importance of the chirality in the environmental chemistry is great. Individual enantiomers exhibit different toxicity and biological activity in the environment and therefore their monitoring by chiral analytical methods is essential.
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Chiral analysis of drug residuals in waste waters
Svobodová, Dagmar ; Opatřilová, Radka (referee) ; Čáslavský, Josef (advisor)
The theoretical part shortly describes chirality with focus on chiral pharmaceuticals. The processes of their absorption, distribution, metabolism and elimination in human body are discussed. These points are very important to understand possible fate of chiral drugs in the environment as there is only little data concerning their environmental behaviour. The occurrence and enantioselective toxicity of chiral drugs is also discussed here. One of the chapters describes non-steroidal anti-inflammatory drugs, as they are analyzed in the wastewater in the experimental part, and their occurrence in the environment. The experimental part describes optimization of the enantioselective HPLC method using Chiralpak AD as column for ibuprofen and ketoprofen. Reproducible separation of enantiomers wasn’t achieved for naproxen. Optimized methods were then applied for analysis of samples from municipal wastewater treatment plant in Brno-Modřice.
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Optical dichroism in vortex electron energy-loss spectroscopy
Ošmera, Martin ; Dub, Petr (referee) ; Konečná, Andrea (advisor)
Vortexové elektronové svazky (VES) nesou orbitální moment hybnosti a při jejich interakci s chirálními strukturami lze pozorovat dichroismus. Ve spektroskopii energiových ztrát elektronů získáme použitím levotočivých VES jiná spekta, než v případě pravotočivých. Tohoto jevu lze využít například v analýze chirálních molekul nebo nanostruktur. Předkládáme semianalytický plně retardovaný model interakce nefokusovaného VES s bodovou chirální polarizovatelnou částicí a numerický kvazistatický model interakce nefokusovaného VES s chirální ,,makroskopickou`` nanostrukturou.
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Switching of spin vortices in magnetic nanodiscs
Hladík, Lukáš ; Pekárková, Jana (referee) ; Urbánek, Michal (advisor)
The diploma thesis deals with the switching of spin vortices in magnetic nanodisks. First, the basic concepts of (micro)magnetism are defined and existing theoretical and experimental achievements in the field of switching of the two basic characteristics (chirality and polarity) of magnetic vortex are summarized. Then the principle of dynamic switching of magnetic vortex chirality using in-plane magnetic field pulse with a well defined amplitude and duration is presented. There is no need to use a certain shape of nanodisks or asymmetry in magnetic field distribution. Nanostructures were prepared by the multi-step electron beam lithography and ion beam sputtering. Individual steps of sample preparation and optimization for the magnetization dynamics measurements are described. Finally, the experimental measurements of the dynamic switching of chirality on prepared samples obtained by transmission x-ray microscopy at the synchrotron Advanced Light Source at Berkeley, USA are presented and discussed.
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Chemical and Physical Properties of Single Molecules and Their Assemblies Adsorbed on Solid Surfaces
Houska, Václav ; Starý, Ivo (advisor) ; Mazal, Ctibor (referee) ; Církva, Vladimír (referee)
Interaction of organic molecules with solid surfaces represents a key area of physical-chemistry research. From heterogenous catalysis to OLED displays, in numerous such systems molecules interact on interfaces, and understanding their behavior is crucial for the correct operation of such applications. In this work, I focused on the study of large π-conjugated macrocycles based on dibenzo[5]helicenes with emphasis on their behavior on graphite surface. The chemical synthesis of the investigated macrocycles was initially impeded by a number of obstacles, particularly by their extremely low solubility. In this work, an efficient solubilization strategy based on the modification of the macrocycles with trityl groups was discovered, which effectively diminishes the intense intermolecular π-π interactions. This opened a path towards a subsequent study of the compound's properties. The attention was focused mainly on a trimer, which was successfully fully characterized, enabling further experiments. Since only a few tens of milligrams of the trimer was prepared, and some stereoisomers were isolated in only microscopic amounts, it was important to develop a suitable experimental methodology. These methods were successfully employed in the measurement of the isomerization kinetics, which allowed us to map...
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Analysis and modifications of 1D nanostructures
Kachtík, Lukáš ; Houben,, Lothar (referee) ; Šlouf,, Miroslav (referee) ; Kolíbal, Miroslav (advisor)
Tato disertační práce se zabývá strukturální a spektrální analýzou 1D nanostruktur. Nejprve jsou představeny techniky pro určení krystalografické struktury, stejně jako spektroskopické techniky, které byly použity pro tuto analýzu – jejich popis a možnosti. Disertace pokračuje analýzou InAs a Ge nanodrátů, kde se analýza zaměřuje na krystalografický směr růstu těchto nanodrátů a jejich dopování. Následující kapitola zahrnuje analýzu vícestěnných WS2 nanotrubic pomocí Ramanovy spektroskopie a postup, pomocí kterého by bylo možné spočítat počet stěn těchto nanotrubic. Disertace pokračuje analýzou WOx nanodrátů, které vznikly po oxidaci WS2 nanotrubic. Následuje nejobsáhlejší kapitola zaměřující se na určení chirality nejsvrchnější stěny vícestěnné WS2 nanotrubice, která mimo jiné odhaluje i proces růstu jednotlivých stěn při tvorbě těchto nanotrubic. V příloze je pak popsán postup, při kterém byl vytvořen autoregulační prvek vyhřívání držáku vzorků rastrovacího elektronového mikroskopu – jak hardwarová, tak softwarová část.
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Mechanisms of symmetry breaking during embryogenesis
Ždímalová, Michaela ; Lánský, Zdeněk (advisor) ; Búran, Peter (referee)
Left-right symmetry breaking is crucial for correct body development of many organisms, including humans. The fact that the left-right asymmetry is established consistently in all healthy individuals of given species fascinates researchers for a long time. Although several models offering a mechanistic insight to this phenomenon were proposed or already accepted, they lack a sufficient molecular description or do not explain all cases. A model of acto-myosin flows - intracellular counter-rotating flows driven by an active torque generation in acto-myosin cortex - leading to the left-right symmetry breaking during embryogenesis is a topic of particular interest in current research. This thesis introduces the problematics of acto-myosin flows in a context of the previous research related to the left-right symmetry breaking. Since the left-right asymmetry is tightly associated with chirality at different scales, this thesis also discusses the current knowledge about possible processes of propagating chirality of molecules to the larger scale. 1
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Optical dichroism in vortex electron energy-loss spectroscopy
Ošmera, Martin ; Dub, Petr (referee) ; Konečná, Andrea (advisor)
Vortexové elektronové svazky (VES) nesou orbitální moment hybnosti a při jejich interakci s chirálními strukturami lze pozorovat dichroismus. Ve spektroskopii energiových ztrát elektronů získáme použitím levotočivých VES jiná spekta, než v případě pravotočivých. Tohoto jevu lze využít například v analýze chirálních molekul nebo nanostruktur. Předkládáme semianalytický plně retardovaný model interakce nefokusovaného VES s bodovou chirální polarizovatelnou částicí a numerický kvazistatický model interakce nefokusovaného VES s chirální ,,makroskopickou`` nanostrukturou.
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The synthesis of π-electron systems suitable for transfer and retention of charges
Nejedlý, Jindřich ; Starý, Ivo (advisor) ; Tobrman, Tomáš (referee) ; Storch, Jan (referee)
The aim of my Thesis was to develop a general synthetic methodology for the preparation of long helicenes equipped with suitable functional groups that control their solubility or serve as anchoring groups for attachment to metallic surfaces, especially gold. The well-established transition metal catalyzed [2+2+2] cyclotrimerization of triynes was selected as the key scaffold-forming transformation in the synthesis of long helicenes because of its high regioselectivity, atom efficiency, functional group tolerance and general robustness. A modular approach was used for the preparation of the starting oligoynes, thus enabling a high level of their structural diversity. Individual resorcinol- based aromatic building blocks were interconnected by Sonogashira cross-coupling reactions, providing complex cyclization precursors encompassing up to twelve alkyne units pre-arranged for the multiple [2+2+2] cycloisomerization to produce three six- membered rings from each set of three neighboring alkyne units. Thus, a small series of long helicenes with up to 19 rings constituting the helical scaffold was synthesized. The quadruple cyclization leading to the longest oxahelicene prepared to date was performed in a high-temperature-high-pressure flow reactor at 250 řC in the presence of CpCo(CO)2. The set of...
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Algebraic approaches to elementary excitations in media with broken spatial or time-reversal symmetry
Erb, Kay Condie ; Hlinka, Jiří (advisor) ; Mokrý, Pavel (referee) ; Schranz, Wilfried (referee)
Title: Algebraic Approaches to Elementary Excitations in Media with Broken Spatial or Time-reversal Symmetry Author: Kay Condie Erb Institute: Institute of Physics of the Czech Academy of Sciences Supervisor: Ing. Jiří Hlinka, Ph.D., Institute of Physics of the Czech Academy of Sciences Abstract: Structural phase transitions with macroscopic symmetry breaking can be divided into 212 non-magnetic species according to the mutual spatial orien- tation of the point groups of both phases. Classification into the given species implies a set of universal transition properties such as the number of macroscopic domain states of the low-symmetry phase and their distinguishability by order parameter. In this work, the distinguishability of macroscopic domain states by all order pa- rameters which transform as vectors or vectorlike quantities (called bidirectors) was studied. For solving this task, a computer algorithm was designed which enabled an explicit listing of all vector and vectorlike order parameters, not only for the 212 non-magnetic species, but even for all 1602 magnetic species which includes transitions between crystallographic gray and bicolor point groups. In addition, irreducible representations of the 122 magnetic crystallographic point groups which transform as vectors or vectorlike quantities are...
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