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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Využití různých frakcionačních technik pro studium struktury ICP / Application of different fractionation techniques for structure determination of ICP

Dostálová, Dagmar January 2015 (has links)
Impact E/P copolymer (ICP) is produced using gas-phase polymerization catalysed by Ziegler-Natta catalysts. This material with its excellent mechanical properties is used in many industries, for example in automotive industry to produce bumpers or instrument panels. Its properties depend on chemical structure which was analysed using DSC, 13C NMR and GPC. It was used 6 different samples of ICP for studies, the chosen samples have different ratio between ethylene and propylene in their copolymer phase. The samples were fractionated using preparative TREF and solvent extraction to obtain fractions, which composition depends on elution temperature. Obtained fractions and original samples were subsequently analysed using above-mentioned methods.
2

Studium růstu metastabilních tenkých vrstev fcc Fe na Cu/Si(100) substrátech / Growth of metastable fcc Fe thin films on Cu/Si(100) substrates

Horký, Michal January 2016 (has links)
This diploma thesis deals with the preparation of epitaxially grown metastable paramagnetic Fe films alloyed by Ni on Cu/Si(100) substrates at RT. Molecular beam epitaxy of Cu(100) buffer layer was performed on H-Si(100) native SiO2 free samples treated by etching in HF or thermal treatment. The epitaxially grown Cu layers with thickness ranging from 50 up to 130 nm serves as suitable substrate for the deposition of 44-ML-thick paramagnetic Fe78Ni22. The film growth was taking place in CO atmosphere and as well as Ni it led to paramagnetic film stabilization. The structural and magnetic ion-beam-induced transformation of desired Fe-Ni structure was performed and propeties of irradiated films were characterized afterwards by MOKE. Then some specific patterns on Si(100) by e-beam litography were fabricated and they served as suitable matrix for Cu(100) buffer layer and paramagnetic Fe. Prepared Si(100), globally and locally deposited metal films were examined by LEED, XPS, AFM, AES, SEM a STM. The recorded results showed the possibility of paramagnetic films preparation on H-Si(100) where it was possible to make ferromagnetic patterns on paramagnetic background by irradiation of specific ion dose.
3

Vývoj aktinoidového magnetismu v hydridech na bázi uranu a dalších vybraných systémech / Variations of actinide magnetism in uranium-base hydrides and other selected systems

Adamska, Anna Maria January 2011 (has links)
Title: Variations of actinide magnetism in uranium-base hydrides and other selected systems. Author: Anna Maria Adamska Department / Institute: Department of Condensed Matter Physics Supervisor of the doctoral thesis: Doc. RNDr. Ladislav Havela, CSc., the Department of Condensed Matter Physics Faculty of Mathematics and Physics Charles University, Prague, Czech Republic and Assoc. Prof. Dr. hab. Nhu-Tarnawska Hoa Kim Ngan, Institute of Physics, Pedagogical University, Kraków, Poland. Abstract: Actinide magnetism was studied in three different types of systems. Variations of magnetic properties of UTGe hydrides as a function of hydrogen concentration prove that doping of U intermetallics by interstitial hydrogen leads to stronger magnetic properties, primarily caused by an increase of the inter-uranium separation. Sputter-deposited UFe2+x films, which are derived from the UFe2 Laves phase but have an amorphous structure, exhibit an increase of the Curie temperarture (to more than 400 K) with the Fe excess, which could not be achieved in the bulk. This is understood as a result of the prominent role of the 3d magnetism of Fe. Notoriously weakly magnetic plutonium was studied in the form of the alloy in the ζ-phase, which exists between 35 and 70 % U in Pu. Its susceptibility increases in a comparison to pure...
4

Charakterizace polypropylénu metalocenového typu s úzkou distribucí molekulových hmotností / CHARACTERIZATION OF METALLOCENE-MADE POLYPROPYLENE WITH NARROW DISTRIBUTION OF MOLECULAR WEIGHT

Fojtlová, Lucie January 2013 (has links)
Metallocene based polypropylene (mPP) with very narrow distribution of molecular weight was peroxide-degraded to materials of four different molecular weights including the original mPP labeled MET1–MET3 and MET0, respectively. Double bonds formed after peroxide-degradation was proved on material surfaces by FTIR-ATR (attenuated total reflection of Fourier-transformed infrared spectroscopy). The decreasing molecular weight led to gradual decrease of the tensile strength, tensile modulus as well as the strain and to the decrease of the temperature of thermal decomposition. Confocal laser scanning microscopy (CLSM) of chemically etched surfaces of MET0–MET3 revealed supramolecular structure of commonly occurred structure (radical spherulites) but also supramolecular structure of form (sheaf-like structure). The latter was proved by XRD together with the fact that the content of form decreases with decreasing molecular weight. The mentioned structure differences were not visible on DSC curves because the amount of structure was small and melting temperature, temperature of crystallization and the degree of crystallinity remained the same for all four types of mPP. The structure of the original materials was also characterized after isothermal crystallization performed on differential scanning calorimetry (DSC) and under polarizing optical microscope (POM). The first was performed at 120–126 °C and the latter at 130 °C (Tic). The materials obtained on DSC always contained the structure and its amount increased with increasing Tic whereas higher content of form was always in MET0 with respect to MET3. The structure was proved by XRD and also by DSC heating run followed immediately after the isothermal process. The latter revealed two endotherms belonging to melting of and forms. The presence of form was on the surfaces proved by CLSM. The formation of structure was in-situ observed on POM and the amount of it decreased with decreasing molecular weight. The spherulite growth rate increased with decreasing molecular weight whereas the rate of crystalline portion expressed as half-time of crystallization decreased with decreasing molecular weight.
5

Vliv různé technologie mletí a mechanické aktivace na vlastnosti hydraulických pojiv / Effects of the different grinding technology and of mechanical activation on the properties of hydraulic binders

Hladík, Václav January 2018 (has links)
This diploma thesis mainly tracks the effect of grinding technology on the final properties of portland cement and selected pozzolanic materials. For grinding of portland cement, was also observed the effect of storage time on the final mechanical properties and hydratation process. Pozzolan activity of selected materials was monitored by evaluation of the reaction with CaO by differential thermal analysis.
6

Příprava a testování SNOM sond speciálních vlastností / Preparation and testing of SNOM probes

Bobek, Juraj January 2019 (has links)
Fotonická krystalická vlákna (PCF) představují slibný nástroj pro spojení technik známých z mikroskopie rastrovací sondou, elektronové mikroskopie a systémů pro vstřikování plynu. Přivedení světla a přenos pracovního plynu současně do blízkosti vzorku umístěného uvnitř elektronového mikroskopu přináší nové možnosti experimentů. PCF by mohly být použity nejen k charakterizaci nebo modifikaci struktur na mikroskopické úrovni, ale také k jejich výrobě. Tato práce se zabývá výzkumem literárních zdrojů s tématikou fotonických krystalů s důrazem na PCF. Leptání PCF pomocí kyseliny fluorovodíkové bez poškození jejich vnitřní struktury je experimentálně studováno s velkou precizností. Optické vlastnosti závislé na geometrii PCF jsou testovány pro různé modifikace PCF. Dále se práce zabývá spojením PCF s mikroskopií atomárních sil a následnou integrací do elektronového mikroskopu.
7

Strukturní a morfologická charakterizace polyamidových spon / Structural and morphological characterization of polyamide buckles

Kubíčková, Eva January 2016 (has links)
The work deals with structrural and morphological characterization of polyamide buckles used to fasten webbins. The buckles were produced in five different years, a few of those produced in 2000 and 2004 were broken. The aime is to determine the type of polyamide and the cause of fracture of the buckles during using. The buckles were characterized in terms of structure and composition by Fourier-transform infrared spectroscopy in a mode of attenuated total reflaction, differential scanning calorimetry, thermogravimetry and X-ray diffraction. The buckles were made of polyamide 12. The broken buckles showed higher melting point, lower thermal stability and, in addition to modification it also contains modification, which is more fragile and probably represents the cause of fracture.
8

Sledování melitelnosti slínkových minerálů / Study of the grindability of the clinker minerals

Červinková, Lenka January 2017 (has links)
The thesis deals with the influence of free various technological grinding processes of pure clinker minerals. The goals is to synthetically prepare pure clinker minerals and monitor the effect of the duration of the grinding process and monitor the impact of grinding technology on their crystallinity. A laser granulometry and XRD analysis are used for evaluation.
9

Důsledky tvorby anortitu v keramickém střepu / Results of Anorthite Creation in ceramic Body

Beránková, Karla January 2012 (has links)
Anorthite is crystalline phase in the ceramic body. Is acquired on burning a mixture of calcium ceramic raw material. This work deals with the influence on the resulting properties of anorthite ceramic body, especially flexural strength, porosity, shrinkage, thermal expansion coefficient. And the influence of different CaO sources on the properties. As a source of CaO was used calcium carbonate, calcium hydroxide and fluid fly ash.

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