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Measurement of mechanical properties of thin films using the bulge test technique
Holzer, Jakub ; Cieslar, Miroslav (referee) ; Kruml, Tomáš (advisor)
Main objective of this diploma thesis is to finish a construction of the Bulge test apparatus for measurement of thin films, perform first tests on commercially available Si3N4 membranes and bilayer membrane with aluminium. First part of the thesis is focused mainly on literature review of current knowledge regarding this topic and other methods of thin films testing. Experimental part deals with construction of apparatus, methodology of data evaluation and results of the measurement. The thin films of interest are fabricated as amorphous silicon nitride or bilayer of mentioned nitride and either aluminium, titanium or Ta-B-C layer. The apparatus has been built in house in collaboration with Institute of Scientific Instruments of CAS. Both reliability and repeatability of this method has been tested on over 160 measurements of commercially available membrane. The results of measurements are compared with literature and nanoindentation test. More detailed data analysis is currently under development with colleagues at Institute of Physics of Materials. It has been proven beyond doubt that Bulge test method and constructed apparatus are suitable for the measurement of several mechanical properties of thin films.
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Characterization of morphological and physico-chemical properties of microorganisms and components of cell by atomic force microscopy
Blaňka, Ondřej ; Smilek, Jiří (referee) ; Slaninová, Eva (advisor)
The aim of this bachelor thesis was to characterize Rhodospirillum rubrum bacterial cells that produce polyhydroxyalkanotate (PHA) and Rhodospirillum rubrum phaC without the ability to produce intracellular PHA granules using atomic force microscopy. Furthermore, isolated polyhydroxyalkanoate granules in their native state were also characterized by this method. Poly-L-lysine was used in the preparation of the samples, specifically for fixation of bacterial cells and isolated PHA granules, and was applied to slides that had been exposed to plasma at a concentration of 0.01 mg/ml. The tip tested was the MLCT - A tip. The first characteristics obtained were topographic images of Rhodospirillum rubrum and Rhodospirillum rubrum phaC cells and isolated PHA granules. The bacterial cells and PHA granules were further characterized using Young's modulus. To obtain it, a method was designed in which whole cells and PHA granules were first imaged, respectively, and then, in the case of cells, measurements were made targeting individual locations on the cell. The measured data were first evaluated in JPK Data Processing software using the Hertzian data approximation model. This evaluation proved to be unreliable, so a second method was devised using the directive lines obtained with the steep parts of the "extend" curve to evaluate. Whole-cell measurement was chosen as a more reliable measurement because it yielded smaller deviations and provided information about the entire surface of the cell or granule. The Rhodospirillum rubrum directive was (4.5±1.5) nN/µm and for Rhodospirillum rubrum phaC was (14.1±4.4) nN/µm. This confirmed the hypothesis that Rhodospirillum rubrum cells containing PHA granules exhibit different stiffness compared to Rhodospirillum rubrum phaC cells without the presence of PHA granules. The directive for isolated PHA granules was determined to be (9.0±1.0) nN/µm. When compared with the directives of bacterial cells, it shows that the PHA granules exhibit a stiffness that lies between that of Rhodospirillum rubrum and Rhodospirillum rubrum phaC.
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Utilization of dynamic mechanical analysis as an add-on module of oscillatory rheometry for hydrogels
Kopecký, Jiří ; Venerová, Tereza (referee) ; Smilek, Jiří (advisor)
Bakalářská práce se zabývá optimalizací dynamické mechanické analýzy a jejím využitím pro charakterizaci hydrogelů s různým typem síťování. Při optimalizaci byly řešeny problémy se správnou přípravou vzorků pro co nejlepší možné výsledky, výběr nejvhodnější geometrie pro měření vybraných hydrogelů a následně byl sepsán podrobný návod pro používání reometru a nastavení softwaru Trios. Dále pak byly diskutovány výsledky z měření pomocí oscilační smykové reometrie a následné porovnání výsledků mezi dynamickou mechanickou analýzou a oscilační smykovou reometrií.
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Stiffness anisotropy of Brno Tegel determined by continuous loading in triaxial tests
Mohyla, Tomáš ; Boháč, Jan (advisor) ; Miča, Lumír (referee)
This Thesis deals with the determination of Young's modulus and Poisson's ratio from the measurement of small strains (10-3 - 10-5 ) in triaxial tests on the overconsolidated Miocene clay from Moravia (Brno Tegel). The tests were performed in a hydraulic triaxial chamber, fitted with submersible local LVDT sensors, which were fixed directly on the sample. The tests were carried out on undisturbed samples of standard height and diameter (76x38 mm). There were three types of tests - isotropic loading probe, axial loading probe and shear test to the failure. The measured data were analyzed and the results were discussed. The research part of the Thesis briefly describes previous works on stiffness of Brno Tegel and also some works on stiffness of similar material to Brno Tegel - London Clay.
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: Viscoelasticity of bones - the methodology of measurement
Cihlář, Zdeněk ; Ďoubal, Stanislav (advisor) ; Kuchařová, Monika (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of biophysics and physical chemistry Candidate: Mgr. Zdeněk Cihlář Supervisor: Prof. RNDr. Ing. Stanislav Ďoubal, CSc. Title of Thesis: Viscoelasticity of bones - the methodology of measurement The aim of the thesis was to verify the methodology of measuring the viscoelastic parameters of human bones using an apparatus enabling the measurement of dynamic characteristics. The method is based on measurement of deformation response of samples to short or rectangular impulse of force. The samples were obtained from femoral head. The methodology is therefore based on measuring of creep curves and impulse characteristics. Resulting damped oscillations were analysed. The transient and impulse characteristics in bending stress and twisting stress were obtained. Based on these characteristics, viscoelastic parameters of samples were determined (Young modulus, shear modulus and viscosity). The Poisson's number, indicating the ratio of transverse contraction to longitudinal extension of the material during deformation, was calculated using the values of Young's modulus and shear modulus. The measured values of the Young's modulus in bending stress vary in the range from 62MPa to 670MPa. The values of the shear stress modulus range...
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Measurement of mechanical properties of thin films using the bulge test technique
Holzer, Jakub ; Cieslar, Miroslav (referee) ; Kruml, Tomáš (advisor)
Main objective of this diploma thesis is to finish a construction of the Bulge test apparatus for measurement of thin films, perform first tests on commercially available Si3N4 membranes and bilayer membrane with aluminium. First part of the thesis is focused mainly on literature review of current knowledge regarding this topic and other methods of thin films testing. Experimental part deals with construction of apparatus, methodology of data evaluation and results of the measurement. The thin films of interest are fabricated as amorphous silicon nitride or bilayer of mentioned nitride and either aluminium, titanium or Ta-B-C layer. The apparatus has been built in house in collaboration with Institute of Scientific Instruments of CAS. Both reliability and repeatability of this method has been tested on over 160 measurements of commercially available membrane. The results of measurements are compared with literature and nanoindentation test. More detailed data analysis is currently under development with colleagues at Institute of Physics of Materials. It has been proven beyond doubt that Bulge test method and constructed apparatus are suitable for the measurement of several mechanical properties of thin films.
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Stiffness anisotropy of Brno Tegel determined by continuous loading in triaxial tests
Mohyla, Tomáš ; Boháč, Jan (advisor) ; Miča, Lumír (referee)
This Thesis deals with the determination of Young's modulus and Poisson's ratio from the measurement of small strains (10-3 - 10-5 ) in triaxial tests on the overconsolidated Miocene clay from Moravia (Brno Tegel). The tests were performed in a hydraulic triaxial chamber, fitted with submersible local LVDT sensors, which were fixed directly on the sample. The tests were carried out on undisturbed samples of standard height and diameter (76x38 mm). There were three types of tests - isotropic loading probe, axial loading probe and shear test to the failure. The measured data were analyzed and the results were discussed. The research part of the Thesis briefly describes previous works on stiffness of Brno Tegel and also some works on stiffness of similar material to Brno Tegel - London Clay.
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Nuclear myosin 1 and its role in the regulation of plasma membrane tension
Petr, Martin ; Hozák, Pavel (advisor) ; Malínský, Jan (referee)
Myosin 1c (Myo1c) is a molecular motor involved in regulation of tension-gated ion channels, exocytosis, endocytosis, motility and other membrane-related events. Moreover, it acts as a dynamic linker between the cell membrane and cortical actin network, contributing to the maintenance of plasma membrane tension. In contrast, nuclear myosin 1 (NM1), an isoform of Myo1c, has been described only in the nucleus where it participates in various nuclear processes, including transcription or chromatin remodeling. However, although traditionally regarded as exclusively cytoplasmic or nuclear, all myosin 1c isoforms participate in nuclear functions and they are present in the cytoplasm as well. The main focus of this study was to characterize the functional significance of NM1 in the cytoplasm. We have found that NM1 localizes to plasma membrane and shows a uniform punctuated distribution with a high concentration at the cell periphery. Moreover, atomic force microscopy measurements of mouse NM1 KO fibroblasts revealed a significant increase in an overall plasma membrane elasticity in comparison to WT cells, indicating a disruption in the regulation of plasma membrane tension caused by the loss of NM1. Since a higher membrane elasticity and deformability is a characteristic marker of cancer cells,...
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: Viscoelasticity of bones - the methodology of measurement
Cihlář, Zdeněk ; Ďoubal, Stanislav (advisor) ; Kuchařová, Monika (referee)
Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of biophysics and physical chemistry Candidate: Mgr. Zdeněk Cihlář Supervisor: Prof. RNDr. Ing. Stanislav Ďoubal, CSc. Title of Thesis: Viscoelasticity of bones - the methodology of measurement The aim of the thesis was to verify the methodology of measuring the viscoelastic parameters of human bones using an apparatus enabling the measurement of dynamic characteristics. The method is based on measurement of deformation response of samples to short or rectangular impulse of force. The samples were obtained from femoral head. The methodology is therefore based on measuring of creep curves and impulse characteristics. Resulting damped oscillations were analysed. The transient and impulse characteristics in bending stress and twisting stress were obtained. Based on these characteristics, viscoelastic parameters of samples were determined (Young modulus, shear modulus and viscosity). The Poisson's number, indicating the ratio of transverse contraction to longitudinal extension of the material during deformation, was calculated using the values of Young's modulus and shear modulus. The measured values of the Young's modulus in bending stress vary in the range from 62MPa to 670MPa. The values of the shear stress modulus range...
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