409 research outputs found

    Studies of Molecular Precursors Used in FEBID Fabrication of Nanostructures

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    The adoption of nanotechnology is increasingly important in many aspects of our daily life influencing the clothes we wear and most of the electronic devices we use while also underpinning the development of drugs and medical techniques that we will need at some point in our lives. The methods by which nanoscale devices are fabricated is changing from a 'top down' etching based procedure to a 'bottom up' molecule by molecule deposition and assembly. The focus of the present research is the development, design, and analysis of new precursors for focused electron beam induced deposition (FEBID) and extreme ultraviolet nanolithography (EUVL) through a large pool of experimental and computational resources. The research is divided into two areas: gas - phase analysis of precursors (largely used for fragment and radicals' analysis, and molecular design) and surface and deposition science (physical deposition of precursors, simulation analysis of surface - molecule interactions and characterization of deposition processes to obtain optimal process parameters for molecular structures). It is necessary to collect data such as cross sections of electron - molecule interactions e.g., dissociative ionization (DI) and dissociative electron attachment (DEA) to provide accurate simulations that can be used to improve the FEBID and EUVL while understanding surface processes such as molecular absorption and diffusion to determine the structure and purity of the nanostructures formed by these methods. The objective of this thesis is to provide a gas - phase and deposition analysis of potential and widely used precursors for FEBID and EUVL at the nanoscale. To achieve this the experimental technique of velocity sliced map imaging (VsMI) was used in conjunction with theoretical tools such as density functional theory (DFT) simulations using Gaussian 16 software and evaluation of cross-section data for molecular dissociation at low electron energies of 0 - 20 eV using Quantemol-N. Results of the gas - phase analysis of negative ionic fragments formed by DEA and DI with their appearance, dissociation and ionization energies, angular distributions and kinetic energies, cross-sections for DEA fragmentation at low energy and excited states calculations at values up to 10 eV are presented. These results are used as the inputs to the models of the FEBID processes. The electronic, structural, and kinetic properties of several FEBID precursors are explored, and FEBID method used to create nanostructures using a Zeiss MeRiT SEM with GEMINI column operated at 20 kV. Analysis of the deposits was performed using EDX and atomic force microscopy (AFM) analysis as well as electron stimulated desorption (ESD) and temperature programmed desorption (TPD). Complementary simulations of the dynamics of processes at the surface were studied using MBN Explorer and surface - molecule interactions with great results in simulating the deposition process of islands and structures (results presented in Chapter 8)

    Selected Analytical Techniques of Solid State, Structure Identification, and Dissolution Testing in Drug Life Cycle

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    The textbook provides an overview of the main techniques applied in pharmaceutical industry, with the focus on solid-state analysis. It discusses spectral methods, thermal analysis, and dissolution testing, explains the theoretical background for each method and shows practical examples from a real-life drug-design and quality control applications. The textbook is thus intended for both pharmacy students and early career professionals

    The Work and Impact of Neighbourhood Development Plans post-adoption

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    Neighbourhood planning was introduced as a new level of participatory neighbourhood-scale planning in England under the 2011 Localism Act. Most of previous studies have focused on mainly the emergence of neighbourhood planning and the preparation of neighbourhood development plans. There are no in-depth academic accounts of neighbourhood development plans ‘post-adoption’, whilst development plans in England have considerable and practical power to influence and shape the growth of the real world. This thesis aims to identify and explore the work and impact of neighbourhood development plans after their adoption based on empirical evidence, tracing how the neighbourhood development plans are used within the planning system and contexts. To do this, multiple embedded case study design with the mixed quantitative and qualitative methods is employed for scrutinising four selected neighbourhood development plans. This thesis deploys and reworks the concept of the communicative work of development plans proposed by Healey (1993) as a conceptual and theoretical tool. This concept is extended to understand the nature and influence of a development plan within its continuing and interactive contexts and further reproduced by reflecting and adjusting to the particularities and attributes of neighbourhood development plans as a relatively new form of community-led plans. The findings highlight that neighbourhood development plans and neighbourhood planning groups themselves seek to remain actively involved in post-adoption planning processes, interacting constantly but sometimes in quite different ways with their external planning environments. The research provides deeper insight into the work of neighbourhood development plans and their interactive power and influence. In turn this insight can provide practical guidelines for those who produce or revise neighbourhood plans and those who support them

    Ciguatoxins

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    Ciguatoxins (CTXs), which are responsible for Ciguatera fish poisoning (CFP), are liposoluble toxins produced by microalgae of the genera Gambierdiscus and Fukuyoa. This book presents 18 scientific papers that offer new information and scientific evidence on: (i) CTX occurrence in aquatic environments, with an emphasis on edible aquatic organisms; (ii) analysis methods for the determination of CTXs; (iii) advances in research on CTX-producing organisms; (iv) environmental factors involved in the presence of CTXs; and (v) the assessment of public health risks related to the presence of CTXs, as well as risk management and mitigation strategies

    Applications of Molecular Dynamics simulations for biomolecular systems and improvements to density-based clustering in the analysis

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    Molecular Dynamics simulations provide a powerful tool to study biomolecular systems with atomistic detail. The key to better understand the function and behaviour of these molecules can often be found in their structural variability. Simulations can help to expose this information that is otherwise experimentally hard or impossible to attain. This work covers two application examples for which a sampling and a characterisation of the conformational ensemble could reveal the structural basis to answer a topical research question. For the fungal toxin phalloidin—a small bicyclic peptide—observed product ratios in different cyclisation reactions could be rationalised by assessing the conformational pre-organisation of precursor fragments. For the C-type lectin receptor langerin, conformational changes induced by different side-chain protonations could deliver an explanation of the pH-dependency in the protein’s calcium-binding. The investigations were accompanied by the continued development of a density-based clustering protocol into a respective software package, which is generally well applicable for the use case of extracting conformational states from Molecular Dynamics data

    Funkční analýza hmyzích reduktáz a desaturáz mastných acylkoenzymů A

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    Lipidy odvozené od mastných kyselin představují důležité biomolekuly. Kromě své hlavní role při stavbě buněk, ukládání energie a signalizaci, slouží celé řadě dalších funkcí, např. jako izolační či nesmáčivé povrchy, obranné látky a feromony. Na úpravách intermediátů vznikajících při biosyn- téze mastných kyselin se podílí celá řada enzymů, mezi něž se řadí např. i desaturázy, které syn- tetizují nenasycené mastné kyseliny, a reduktázy, jež syntetizují mastné alkoholy. Funkčně vysoce diverzifikované desaturázy a reduktázy z hmyzu, jakožto jedněch z nejhojněji zastoupených zvířat na světe, představují podstatný zdroj pro moderní biotechnologii buněčných továren. Tato práce shrnuje dostupné informace o reduktázách a desaturázách a popisuje výsledky, které jsme při jejich studiu získali. U čmeláků jsme identifikovali několik reduktázových transkriptů, jež jsou hojně zastoupeny v samčí feromonové žláze. Příslušné enzymy jsme následně funkčně charakterizovali v kvasinkách a odhadli jejich zapojení do biosyntézy mastných alkoholů v tkáni produkující značkovací feromon. Studované enzymy redukují širokou řadu substrátů, od krátkých mastných acylů (C14) až po velmi dlouhé (C26), od nasycených mastných acylů po polynenasycené. Dále jsme poukázali na to, že na expanzi a následném funkčním rozrůznění čmeláčích...Fatty acid-derived lipids are an important class of biomolecules. In addition to their primary role in cellular architecture, energy storage and signaling, they function in many other ways, e.g. as isolating or waterproof coatings, defense compounds and pheromones. Multiple enzymes mod- ify intermediates originating from fatty acid biosynthetic pathway, including desaturases (FADs) which synthesize unsaturated fatty acids, and reductases (FARs) which synthesize fatty alcohols. Functionally highly diversified fatty acyl-modifying enzymes from insects, one of the most abun- dant animals in the world, present a significant source for modern biotechnology of cell factories. This thesis summarizes available information on the FADs and FARs and describes the results which we have obtained while studying them. In bumblebees, we identified several FAR transcripts which are abundantly expressed in male pheromone-producing tissue. We then functionally characterized the corresponding enzymes in yeasts, and estimated their participation in the biosynthesis of fatty alcohols observed in the mark- ing pheromone-producing tissue. The studied enzymes reduce broad range of substrates, from short fatty acyls (e.g. C14) to very long ones (e.g. C26), from saturated fatty acyls to polyunsatu- rated ones. We also found...Katedra biochemieDepartment of BiochemistryPřírodovědecká fakultaFaculty of Scienc

    Sedimentation on the continental margin off the Orange River and the Namib Desert

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    This study is the first detailed reconnaissance survey of the bathymetry, bedrock geology and the superficial sediments of the continental margin off the Orange River and the Namib Desert. The study area is bounded by latitudes 25° and 3o0 s. The Orange shelf is up to 100 km wide and 200 m deep, and the Walvis shelf off Lllderitz is up to 80 km wide and 400 m deep, the inner shelf is underlain by. Precambrian bedrock and is usually less than lOi km wide and shallower than 100 m. Tripp Seamount penetrate the upper slope in a depth of 1000 m and rises to within 150 m of sea level, the level of the Orange Banks on the outer orange shelf. South of the Orange River unfossiliferous ferruginous sandstones and mudstones crop out as seaward-dipping scarps on the middle shelf. North of the Orange River, similar scarps are composed of quartzose lime wackestones, identical to a Palaeogene suite on the Agulhas Bank. The shallow outer orange shelf is underlain in places by Upper Middle Miocene nummulitic _limestones, which are overlain by glauconitic conglomeratic phosphorites. Quartz-free algal limestones are found both on the Orange Banks and on the tip of Tripp Seamount. Authigenic pyrite and gypsum were found in two samples of semi-consolidated Neogene clay on the slope off Lüderitz. Pyrite is formed by combining teErigen-. ous adsorbed iron with sulphur released by anaerobic reduction of sea-water sulphate. The dissolution of planktonic foraminiferal tests provides calcium ions which combine with sulphate to form gypsum, once the calcium/sulphate solubility product is exceeded. On the Walvis shelf off LUderitz residual glauconite was reworked from older Neogene sediments, particularly on Lllderitz Bank. North of latitude 26°S residual phosphorite pellets were probably formed in Neogene diatomaceous oozes and then concentrated during a Late-Tertiary regression. Erosion of semi-consolidated .Neogene clays and ?Palaeogene quartzose' limestones. on ·the middle and outer Walvis shelf led to deposition of very fine residual quartz sand south of LUderitz. Coarse quartz ~and was reworked from littoral sandstones on the middle shelf south of the Orange River. The effect on sedimentation in the hinterland of poleward shifts of climatic belts during Quaternary interglacials and the reverse movement during glacials is assessed. Recent terrigenous sediments are derived by erosion of poorly consolidated Karoo sediments in the catchment of the Upper Orange. Erratic but powerful floods transport the sediments to the coast in suspension each summer. At the mouth in tense wave action dominates the submarine delta of the Orange River and fractionates the sediment load. Sand is transported equatorwards by littoral drift and is blown off beaches towards the Namib Sand Sea during violent Trade-Wind gales each sunnner. In contrast, silt and clay are transported polewards by a countercurrent, particularly during westerly winter storms. Recent biogenic sedimentation is controlled by upwelling in the B~nguela Current System, which is most intense off the wind dominated Sperrgebiet, south of LUderitz. Weaker upwelling off the Orange River allows oceanic planktonic foraminifera to penetrate to the middle shelf, whereas on the Walvis shelf in the study area they only reach the outer shelf. Towards latitude 25°s the Benguela Current System decays and interacts with poleward-flowing warm oxygen-poor water. Periodic mass mortalities of oxygen-starved phytoplankton lead to some of the most organic-rich sediments in the world
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