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STRAIN ENGINEERING OF THE ELECTRONIC STRUCTURE OF 2D MATERIALS
del Corro, Elena ; Peňa-Alvarez, M. ; Morales-García, A. ; Bouša, Milan ; Řáhová, Jaroslava ; Kavan, Ladislav ; Kalbáč, Martin ; Frank, Otakar
The research on graphene has attracted much attention since its first successful preparation in 2004. It possesses many unique properties, such as an extreme stiffness and strength, high electron mobility, ballistic transport even at room temperature, superior thermal conductivity and many others. The affection for graphene was followed swiftly by a keen interest in other two dimensional materials like transition metal dichalcogenides. As has been predicted and in part proven experimentally, the electronic properties of these materials can be modified by various means. The most common ones include covalent or non-covalent chemistry, electrochemical, gate or atomic doping, or quantum confinement. None of these methods has proven universal enough in terms of the devices' characteristics or scalability. However, another approach is known mechanical strain/stress, but experiments in that direction are scarce, in spite of their high promises.\nThe primary challenge consists in the understanding of the mechanical properties of 2D materials and in the ability to quantify the lattice deformation. Several techniques can be then used to apply strain to the specimens and thus to induce changes in their electronic structure. We will review their basic concepts and some of the examples so far documented experimentally and/or theoretically.
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Sorption and Stabilization of Metals/Mettalloids by Innovative Synthesized Sorbent Amochar.
Ouředníček, P. ; Trakal, L. ; Komárek, M. ; Pohořelý, Michael
Remediation of contaminated soil which is based on stabilization and immobilization of potential\nhazardous substance by sorption materials has been studied intensively nowadays. Biochar – activated organic carbon belongs to this group of stabilizing agents which can adsorb wide range of contaminants, including metals/metalloids. Surface area of the biochars is quite large in general and functional groups (e.g. COO–) can form chelates or alkaline elements on the surface, which is represented by cation exchange capacity. Altogether with the high pH values (7.00 – 10.00), biochars are quite effective sorbents and can adsorb metals/metalloids from the solution (ground water), especially in acidic soils (in the environments affected by intensive mining activities). Sorption\neffectiveness can be increased (especially for As (V) or Cr (VI) sorption) by modification of biochar by various types of secondary oxides. Innovative sorbent AMOchar (AMO + biochar) has been synthesized currently. The product was prepared by adding of biochar to the reaction solution during amorphous manganese oxide (AMO) synthesis. The AMOchar was formed mainly by Mn-oxalates which had coated surface of the pristine biochar. AMOchar composite was able to remove significantly higher amounts of various metal(loid)s from the solution despite the rather high pH of the material. Sorption effectiveness was high not only in case of Pb (II) sorption (almost 99%), and Cd(II) (51.2%), but also a very high amount of As(V), 91.4%. Additionally, both AMOchar composite was able to reduce Mn leaching. This can avoid potential post-contamination caused by the dissolution of less stable Mn-oxalates as observed in the pure AMO.
Fulltext: content.csg -  PDF
Plný tet: SKMBT_22316111113040 - PDF
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Cooperation of high schools with external contractors in preparing school educational programs
Tulach, David ; Lačev, Alek (advisor) ; Hochel, Matej (referee)
This thesis, Cooperation of high schools with external contractors in preparing school educational programs, deals with the question whether it would be possible and beneficial for high schools to cooperate with companies on the preparation or modification of their educational programs, with the goal of improving the quality of education. After initial contributions from experts who provided negative replies to this question, the view was focused on the root of the issue - what are the historical pillars of public schools and pedagogy, what does science say about learning and teaching, how pedagogy reacts to the crisis of science. After comparing literal sources and results from interview with the experts, in combination with a trace and activity analysis, a theory was established that public education is reaching a point of crisis, has not changed in its essence since its beginning and that the best solution might be the establishment of alternative educational institutions.
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Single particle analysis of size-segregated aerosol in Prague city center
Marvanová, S. ; Skoupý, Radim ; Kulich, P. ; Bendl, J. ; Hovorka, J. ; Machala, M.
Particulate matter (PM) is omnipresent pollutant in the ambient air known to cause cardiovascular and respiratory diseases (WHO 2004). Recently, outdoor air pollution and particulate matter in outdoor air pollution were classified as carcinogenic to humans, Group 1 (IARC 2015). Especially, ambient PM of aerodynamic diameter < 100 nm, ultrafine particles, appears to be of great importance due to its high specific surface area and high number concentration (Hughes et al. 1998). Ultrafine particles also easily enter and are being transferred in organisms, and interact with cells and subcellular components (Oberdorster et al. 2005). As the evidence of ultrafine PM significance increased, size-fractionated PMs sampled by various cascade impactors have been employed into the toxicological studies on cell cultures or isolated cells, using the organic extracts of size-fractionated PMs (Topinka et al. 2013, Topinka et al. 2015) or directly the size-fractionated particles (Becker et al. 2003, Ramgolam et al. 2009, Reibman et al. 2002, Loxham et al. 2013, Jalava et al. 2006, Thomson et al. 2015, Jalava et al. 2015). The aim of this study was to evaluate shape and composition of size-segregated aerosol particles, sampled by high volume cascade impactor, using electron microscopy and energy dispersive X-ray spectroscopy (EDX).
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Possibilities in monitoring of laser welding process
Horník, Petr ; Mrňa, Libor
With increasing demands on the quality of the welds, it is usual to apply automated machine welding with monitoring of the welding process. The resulting quality of the weld is largely affected by the behavior of keyhole. However, its direct observation during the welding process is practically impossible and it is necessary to use indirect methods. At ISI we develop optical methods of monitoring the process based on analysis of radiation of laser-induced plasma using Fourier and autocorrelation analysis. Observation of keyhole inlet opening is partially possible through a coaxial camera mounted on the welding head and the subsequent image processing. A high-speed rear camera to understand the dynamics of the plasma plume. Through optical spectroscopy of the plume, we can study the excitation of elements in a material. Shielding gas flow can be visualized using schlieren method.
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Noise, Transport and Structural Properties of High Energy Radiation Detectors Based on CdTe
Šik, Ondřej ; Lazar, Josef (referee) ; Navrátil, Vladislav (referee) ; Grmela, Lubomír (advisor)
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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New Methods for Increasing Efficiency and Speed of Functional Verification
Zachariášová, Marcela ; Dohnal, Jan (referee) ; Steininger, Andreas (referee) ; Kotásek, Zdeněk (advisor)
Při vývoji současných číslicových systémů, např. vestavěných systému a počítačového hardware, je nutné hledat postupy, jak zvýšit jejich spolehlivost. Jednou z možností je zvyšování efektivity a rychlosti verifikačních procesů, které se provádějí v raných fázích návrhu. V této dizertační práci se pozornost věnuje verifikačnímu přístupu s názvem funkční verifikace. Je identifikováno několik výzev a problému týkajících se efektivity a rychlosti funkční verifikace a ty jsou následně řešeny v cílech dizertační práce. První cíl se zaměřuje na redukci simulačního času v průběhu verifikace komplexních systémů. Důvodem je, že simulace inherentně paralelního hardwarového systému trvá velmi dlouho v porovnání s během v skutečném hardware. Je proto navrhnuta optimalizační technika, která umisťuje verifikovaný systém do FPGA akcelerátoru, zatím co část verifikačního prostředí stále běží v simulaci. Tímto přemístěním je možné výrazně zredukovat simulační režii. Druhý cíl se zabývá ručně připravovanými verifikačními prostředími, která představují výrazné omezení ve verifikační produktivitě. Tato režie však není nutná, protože většina verifikačních prostředí má velice podobnou strukturu, jelikož využívají komponenty standardních verifikačních metodik. Tyto komponenty se jen upravují s ohledem na verifikovaný systém. Proto druhá optimalizační technika analyzuje popis systému na vyšší úrovni abstrakce a automatizuje tvorbu verifikačních prostředí tím, že je automaticky generuje z tohoto vysoko-úrovňového popisu. Třetí cíl zkoumá, jak je možné docílit úplnost verifikace pomocí inteligentní automatizace. Úplnost verifikace se typicky měří pomocí různých metrik pokrytí a verifikace je ukončena, když je dosažena právě vysoká úroveň pokrytí. Proto je navržena třetí optimalizační technika, která řídí generování vstupů pro verifikovaný systém tak, aby tyto vstupy aktivovali současně co nejvíc bodů pokrytí a aby byla rychlost konvergence k maximálnímu pokrytí co nejvyšší. Jako hlavní optimalizační prostředek se používá genetický algoritmus, který je přizpůsoben pro funkční verifikaci a jeho parametry jsou vyladěny pro tuto doménu. Běží na pozadí verifikačního procesu, analyzuje dosažené pokrytí a na základě toho dynamicky upravuje omezující podmínky pro generátor vstupů. Tyto podmínky jsou reprezentovány pravděpodobnostmi, které určují výběr vhodných hodnot ze vstupní domény. Čtvrtý cíl diskutuje, zda je možné znovu použít vstupy z funkční verifikace pro účely regresního testování a optimalizovat je tak, aby byla rychlost testování co nejvyšší. Ve funkční verifikaci je totiž běžné, že vstupy jsou značně redundantní, jelikož jsou produkovány generátorem. Pro regresní testy ale tato redundance není potřebná a proto může být eliminována. Zároveň je ale nutné dbát na to, aby úroveň pokrytí dosáhnutá optimalizovanou sadou byla stejná, jako u té původní. Čtvrtá optimalizační technika toto reflektuje a opět používá genetický algoritmus jako optimalizační prostředek. Tentokrát ale není integrován do procesu verifikace, ale je použit až po její ukončení. Velmi rychle odstraňuje redundanci z původní sady vstupů a výsledná doba simulace je tak značně optimalizována.
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Doped DLC coatings for biomedical applications
Písařík, Petr
Nowadays there are materials having excellent properties for use in medicine (Diamond-like carbon, Hydroxyapatite, …). Diamond-like carbon (DLC) is a metastable form of amorphous carbon containing bonded carbon atoms of sp2 and sp3 hybridized orbital. DLC layers are semiconductors with high mechanical hardness, chemical inertness, low coefficient of friction, high thermal conductivity, good electrical and optical properties, biocompatibility and no cytotoxicity. All properties of the films are not always ideal, so it is necessary to modify the layer. One example of how to modify the properties of thin layers are dopations. The incorporation of dopants in films may lead to greater multifunctionality and much improved properties. Most modifications were made to modify contact angle and surface energy, to reduce internal stresses, to decrease surface roughness, coefficient of friction or wear....
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High normal pressure and hypertension of children and adolescents
KRÁLOVÁ, Kateřina
In children and adolescents, high normal blood pressure is often present. People with high normal blood pressure show a short time prerequisite to the formation of arterial hypertension. Hypertension occurs most often in children as asymptomatic. Increased blood pressure in children is most often discovered during preventive examinations by a general practitioner for children and adolescents. This thesis contains information about the anatomy and physiology of the cardiovascular system, a blood pressure measurement sister, evaluation of blood pressure, high normal pressure, high blood pressure in children, the role of nurses in primary care pediatricians in the area of communication and education, and treatment of high normal pressure and hypertension. Objectives The first goal was to explore how children adhere regime measures for the prevention of high normal pressure and hypertension. It used this research question: How children adhere regime measures for the prevention of high normal pressure and hypertension? The second objective was to determine the role of nurses in the care of children with high normal pressure and hypertension. The second research question is: What is the role of the nurses in taking care of children with a normal high pressure and hypertension? Methods used In the research part of the thesis, we used the method of qualitative research, questioning method and technique-depth interviews. The interviews were recorded on a Dictaphone and then transcribed literally. Four sisters and three mothers did not wish to be recorded, so they were interviewed at polling literally written on paper. For research, two research files were created. The first sample consisted of six nurses, who were working in GP surgery for children and adolescents in the South Region. Second survey consisted of six people selected from among parents of children with high normal pressure and hypertension, also from South Bohemia. Results The transcribed interviews were investigated by open coding method, pencil and paper. Resulted in 9 categories: Cardiovascular disease, role of the nurse, pressure measurement, blood pressure, hypertension, pressure measurement, recommendation, Lifestyle, Leisure. Individual categories were assigned to subcategories, which are encoded core data. Conclusion The first research confirms nurses working in a pediatrician's office for children and adolescents, the most common cardiovascular disease in the general hypertension. They argue that the role of nurses in primary care pediatricians is properly measure blood pressure and make the education of children and parents in the area. The respondents concurred in the principles of how to properly measure blood pressure measurement are available for at least three cuff sizes. Informants have basic information about high normal pressure and hypertension, and said that, in the offices of primary care pediatricians to conduct checks blood pressure of preventive examinations or troubled child. Informants reported that blood pressure control and education on blood pressure occurs, but in the second research study showed that children and adolescents do not comply with the recommended recommendations in this area, perhaps because they are less motivated. Neither sister nor the parents have not mentioned, they would receive educational aids such as brochures and sample menus.The second research showed that parents most often found elevated blood pressure in primary care pediatricians, either for reasons of preventive examinations or difficulty a child. On the control measurements came at least three times. Respondents agreed on the recommendations they received in the office GPCY such as reducing the weight of the child, regular physical activity, restriction of salt and proper diet the child, but not all children and adolescents comply with these recommendations. The research results will be provided to the journal Pediatrics practice.
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