Content: A comprehensive analysis of the molecular and structural components of deer skin and cow hide was undertaken. These skins known to be strong, however they derive their strength from different combinations of molecular and structural properties. Firstly, the physical properties of deer skin and cow hide including the tensile strength, tear strength and denaturation temperature were measured. Secondly, the structure of the collagen fibrils and glycosaminoglycans was investigated using transmission electron microscopy (TEM), and small angle X-ray scattering (SAXS). Finally, the chemical composition of deer skin and cow hide such as amino acids, crosslinks and glycosaminoglycans were analysed. Our results showed that physical properties of deer skin and cow hide are derived from different combinations of several chemical components resulting in different architecture. It was found that the large and “wavy” collagen fibres in deer skin made up of collagen fibrils with small diameters. Additionally, deer skin fibrils appeared to be linked by regular arrays of filaments of large glycosaminoglycans that are distributed uniformly. Deer skin contained higher proportion of trivalent collagen crosslinks. In contrast, the collagen fibrils in cow hide were large, contained a diverse glycosaminoglycan distribution and a higher proportion of tetravalent collagen crosslinks, resulting in straight collagen fibres. This study suggests that although deer skin and cow hide are both strong, they have different structural and molecular features. Take-Away: Deer skin and cow hide have different structural and molecular make up which are reflected in their physical properties particularly strength. Glycosaminoglycans are important for the organisation of collagen fibrils in deer skin and cow hide. Deer skin and cow hide contain different ratios of collagen natural crosslinks which are essential collagen stability.

The aim of the first part of this thesis is to explain the theoretical basis of transmission electron microscopy and to mention fundamental parts of transmission electron microscopes. The next part of this work is focused on possible methods of image segmentation, the use of neural networks in the detection of objects in an image and the subsequent clustering of results. The theoretical part of the thesis is concluded with an explanation of some already published methods of automatic detection of biological structures in microscopic images and theoretical design of the algorithm, which will be subsequently developed. The process of training neural networks in order to automatically detect biological structures in an image is described at the beginning of the practical part. This is followed by an evaluation of the results achieved by these networks. Subsequently, cluster analysis methods are applied to these results, the products of which are compared with each other and also with the results obtained by already published methods.

Tato Diplomová práce je zaměřena na odstranění šumu ze snímků získaných pomocí Transmisního elektronového mikroskopu. V práci jsou popsány principy digitalizace výsledných snímků a popis jednotlivých šumových složek, které vznikají při digitalizaci snímků. Tyto nechtěné složky ovlivňují kvalitu výsledného snímku. Proto byly vybrány filtrační metody založené na minimalizaci totální variace, jejichž principy jsou v této práci popsány. Jako referenční filtrační metoda byla vybrána filtrace pomocí Non-local means filtru. Tento filtr byl vybrán, jelikož v dnešní dobře patří mezi nejvíce využívané metody, které mají vysokou účinnost. Pro objektivní hodnocení kvality filtrací byly použity tyto hodnotící kritéria – SNR, PSNR a SSIM. V závěru této práce, jsou všechny získané výsledky zobrazeny a jsou diskutovány účinnosti jednotlivých filtrační metod.

>Magister Scientiae - MSc / Combating antimicrobial resistant infections caused by nosocomial pathogens poses a major public health problem globally. The widespread use of broad-spectrum antibiotics for the treatment of wound infections has led to the appearance of multidrug-resistant (MDR) microbes which further exacerbates the growth of microbes amongst patients. It may result in prolonged debility of the patient and an increase in healthcare costs due to prolonged hospital stays and expensive treatment regimens to avoid patient-patient transmission. Therefore, it is imperative that alternative sources of treatment to antimicrobial use in wound infections needs to be developed in order to inhibit or kill resistant microbes and to provide point of care medical treatment to the less fortunate at an affordable cost. / 2021-08-30

Au cours de cette étude, nous avons montré que dans les oxydes de fer type perovskite, les ions sulfates (SO42-) pouvaient être utilisés à escient pour apporter de l'anisotropie cristalline et électronique ou bien au contraire pour casser les mises en ordre à longue distance et provoquer l'isotropie du matériau. Ainsi, ce travail a permis d'isoler les composés bidimensionnels : Sr4Fe2.5-x□xO7.25-(3x/2)(SO4)0.5 (avec x=0, 0.25 et 0.5). Ils peuvent être décrits comme une intercroissance SrO/SrFeO2,5/SrFe0,5-x□xO1,25-(3x/2)(SO4)0,5/SrFeO2,5 et cristallisent dans une maille moyenne quadratique I4/mmm (a=ap et c≈29 Å). Les tétraèdres de sulfates non-pontés se présentent de façon transversale par rapport à c ⃗ pour x=0,5 et longitudinale pour x=0 et 0,25 parce que pontés aux pyramides de fer de la couche partagée. Les atomes de fer des couches non-mixtes SrFeO2,5 se situent eux en coordinence pyramidale pour x=0 et pyramidale et octaédrique pour x=0.5 et x=0.25 afin de respecter la trivalence du fer. Quel que soit x, les composés sont antiferromagnétiques de type G (les spins se situant dans le plan (a,b)). Cependant, pour x=0,5, deux configurations magnétiques sont observées, tandis que les composés x=0 et x=0.25 n'en montrent qu'une seule. Dans le composé Sr4Fe2.5□xO7.25(SO4)0.25(CO3)0.25, l'influence des carbonates (CO32-) se ressent directement sur le paramètre d'empilement, qui est plus petit. Cela n'entraîne cependant aucun changement sensible dans les propriétés physiques. Les composés sont des semi-conducteurs présentant de fortes valeurs de résistivité électronique (de l'ordre de 106Ω.cm) et ne sont pas conducteurs ioniques.La phase ordonnée "15R" SrFe0.6Cr0.4O2.8 se désordonne lorsque l'on substitue 10% du fer par des sulfates (SrFe0.5Cr0.4O2.1(SO4)0.1) et adopte une structure pseudo-cubique. Ses propriétés physiques sont alors bouleversées puisque l'on passe d'un comportement ferromagnétique à antiferromagnétique (TN=800K). Ce composé très lacunaire en oxygène montre des défauts structuraux plus ou moins étendus et un comportement de type semi-conducteur. Aucun phénomène de conduction ionique n'est observé. / In this study, we have shown that in perovskite-type iron oxides, sulfate ions (SO42-) can be used to bring structural and electronic anisotropy, or on the contrary to break long distance ordering and cause the isotropy of the material.Thus, this work made it possible to isolate the two-dimensional compounds: Sr4Fe2.5-x□x07.25-(3x/2)(SO4)0.5 (with x = 0.25 and 0.5). They can be described as an intergrowth SrO/SrFeO2,5/SrFe0,5-x□xO1,25-(3x/2)(SO4)0.5/SrFeO2,5 and crystallize in a quadratic mean cell I4/mmm (a=ap et c≈29 Å). The unbridged sulfates tetrahedra are oriented transversely with respect to c ⃗ for x=0.5 and longitudinal for x=0 and 0.25 because bridged to the iron pyramids of the shared layer. The iron atoms of the non-mixed layers SrFeO2,5 are in pyramidal coordination for x=0 and pyramidal and octahedral coordination for x=0.5 and x=0.25, in order to respect the trivalence of iron. However, for x=0.5, two magnetic configurations are observed whereas the compounds x=0 and x=0.25 show only one. In the compound Sr4Fe2.5□xO7.25(SO4)0.25(CO3)0.25, the influence of the carbonates (CO32-) is directly felt on the stacking parameter, which is smaller. The compounds are semiconductors with high electronic resistivity values (of the order of 106Ω.cm) and are not ionic conductors.The ordered phase "15R" SrFe0.6Cr0.4O2.8 becomes disordered when 10% of the iron is substituted with sulfates (SrFe0.5Cr0.4O2.1(SO4)0.1) and adopts a pseudo-cubic structure. Its physical properties are then modified because we switch from a ferromagnetic to an antiferromagnetic behavior (TN=800K). This oxygen-deficient compound shows more or less large structural defects and a semiconductor behavior. No ionic conduction phenomenon is observed.

Present doctoral thesis is focused on electron microscopy and spectroscopy investigation of novel metal-oxide anode catalyst for fuel cell application. Catalyst based on Pt- doped cerium oxide in form of thin layers prepared by simultaneous magnetron sputtering deposition on intermediate carbonaceous films grown on silicon substrate has been studied. The influence of catalyst support composition (a-C and CNx films), deposition time of CeOx layer and other deposition parameters, as deposition rate, composition of working atmosphere and Pt concentration on the morphology of Pt-CeOx layers has been investigated mainly by Transmission Electron Microscopy (TEM). The obtained results have shown that by suitable preparation conditions combination we are able to tune final morphology and composition of catalyst. Composition of carbonaceous films and Pt-CeOx layers was examined by complementary spectroscopy techniques - Energy Dispersive X-ray Spectroscopy (EDX), Electron Energy Loss Spectroscopy (EELS) and X-ray Photoelectron Spectroscopy (XPS). Such prepared porous structures of Pt-CeOx are of promising as anode catalytic material for real fuel cell application. Keywords: cerium oxide, platinum, fuel cell, magnetron sputtering, Transmission Electron Microscopy

We present a colloidal synthesis of quaternary Cu–Zn–In–S (CZIS) nanoplatelets (NPLs) by means of partial cation exchange. Starting with the synthesis of highly monodisperse binary CuS NPLs with lateral dimensions of ∼64 nm and thickness of ∼5 nm, we further performed a cation exchange reaction in which copper was partly replaced by indium, leading to Cu–In–S NPLs. To enhance the stability of the resulting NPLs and to improve their optical properties, we carried out the ZnS shell growth via both the heterogeneous nucleation of ZnS on the NPLs and via partial cation exchange on the surface of the particles. The latter reaction resulted, however, in rather an alloyed than the core/shell structure, whereas the reaction between zinc and sulfur precursors yielded unusual cookie-like hexagonal shaped structure, in which ZnS trigonal extensions grew only on one of the basal planes of the plates along the thickness direction. Upon ZnS growth, the lateral dimensions of the resulting core/shell CZIS/ZnS and alloyed CZIS NPLs distinctly increased to ∼80 and ∼75 nm, respectively. The analysis of the optical properties of the alloyed CZIS NPLs showed photoluminescence (PL) in the range from 780 to 820 nm depending on the reaction time and temperature. This PL signal originated mainly from small nanoparticles formed as a byproduct in the synthesis. In contrast to the alloyed NPLs, PL measurements of the core/shell CZIS/ZnS platelets showed a weak emission in the near-infrared region (PL maximum at approx. 1110 nm), which so far has rarely been reported for the copper chalcogenide-based two-dimensional structures.

Lithium-ion batteries(LIBs) have dominated the energy storage market in the past two decades. The high specific energy, low self-discharge, relatively high power and low maintenance of LIBs enabled the revolution of electronic devices and electric vehicle industry, changed the communication and transportation styles of the modern world. Although the specific energy of LIBs has increased significantly since first commercialized in 1991, it has reached a bottleneck with current electrode materials. To meet the increasing market demand, it is necessary to develop high capacity electrode materials.<div><br></div><div>Current commercial anode material for LIB is graphite which has a specific capacity of 372 mAh g-1. Other group IV elements (silicon (Si), germanium (Ge), tin (Sn)) have much higher capacities. However, group IV elements have large volume change during lithiation/delithiation, leading to pulverization of active materials and disconnection between electrode particles and current collector, resulting in fast capacity fading. To address this issue, it is essential to understand the microstructural evolution of Si, Ge and Sn during cycling.<br></div><div><br></div><div>This dissertation is mainly focused on the morphological and structural evolution of Sn and Ge based materials. In this dissertation, anin situ focused ion beam-scanning electron microscopy (FIB-SEM) method is developed to investigate the microstructuralevolution of a single electrode particle and correlate with its electrochemical performance. This method is applied toall projects. The first project is to investigate the microstructural evolution of a Sn particle during cycling. Surface structures of Sn particles are monitored and correlated with different states of charge. The second project is to investigate the morphological evolution of Ge particles at different conditions. Different structures (nanopores, cracks, intact surface) appear at different cycling rates. The third project is to study selenium doped Ge (GeSe) anodes. GeSe and Ge particles are tested at the same condition. Se doping forms Li-Ge-Se network, provides fast Li transport and buffers volume change. The fourth project is to study the reaction front of Ge particle during lithiation. Micron-sized Ge particles have two reaction fronts and a wedge shape reaction interface, which is different from the well-known core-shell mode. The fifth project is to investigate antimony (Sb)-coated porous Ge particles. The Sb coating suppresses electrolyte decomposition and porous structure alleviates volume change. The results in this dissertation reveal fundamental information about the reaction mechanism of Sn and Ge anode. The results also show the effects of doping, porous structuring and surface coating of anode materials.</div>

This thesis explores nanostructuring in TiSiCN, ZrAlN, and TiAlN thin films deposited by cathodic arc evaporation onto cemented carbide substrates, with intended applications for cutting tools. The three systems were found to exhibit age hardening upon annealing, by different mechanisms, into the superhard regime (≥30 GPa), as determined by a combination of electron microscopy, X-ray diffraction, atom probe tomography, erda, and nanoindentation tech- niques. TiSiCN forms nanocomposite films during growth by virtue of Si segregation to the surface of TiCN nanocrystallites while simultaneously pro- moting renucleation. Thus, the common columnar microstructure of TiCN and low-Si-content (≤5 at. %) TiSiN-films is replaced by a “feather-like” nanos- tructure in high-Si-content (≥10 at. %) TiSiCN films. The presence of C promotes the formation of this structure, and results in an accelerated age hardening beginning at temperatures as low as 700 °C. The thermal stability of the TiSiCN films is, however, decreased compared to the TiSiN system by the loss of Si and interdiffusion of substrate species; C was found to ex- acerbate these processes, which became active at 900 °C. The ZrAlN system forms a two-phase nanostructure during growth consisting of cubic ZrAlN and wurtzite ZrAlN. Upon annealing to 1100 °C, the c-Zr(Al)N portion of the films recovers and semicoherent brick-like w-(Zr)AlN structures are formed. Age hardening by 36 % was obtained before overageing sets in at 1200 °C. As-deposited and annealed solid solution Ti0.33Al0.67N thin films were characterized for the first time by atom probe tomography. The as-deposited film was found to be at the very initial stage of spinodal decomposition, which continued during annealing of the film at 900 °C for 2 h. N preferentially segregates to Al-rich domains in the annealed sample, causing a compositional variation between Ti-rich and Al-rich domains, to maintain the stoichiometry for the developing AlN phase. That effect also compensates for some of the coherency strain formed between cubic domains of TiN and AlN. Finally, a possible Kirkendall effect caused by an imbalance in the metal interdiffusion during the spinodal decomposition was discovered.

Irradiation of metals with energetic particles causes heavy damage effects in microstructure and mechanical properties, which is closely associated with irradiation conditions, presence of impurities, and microstructural features. It has been proposed that the radiation tolerance of a certain material can be enhanced by introducing a high density of interfaces, acting as ‘sinks’ that can frequently involve in attracting, absorbing and annihilating defects. Nanostructured materials with large volume fraction of interfaces, therefore, are assumed to be more radiation tolerant than conventional materials. This thesis focuses on the radiation damage effects in nanostructured Cu via the methods of in-situ TEM (transmission electron microscope) radiation experiments, postirradiation TEM analyses, small-mechanical tests (nanoindentation and micro-pillar compression), and computer simulations (molecular dynamics and phase-field modeling). We design and fabricate nanostructured Cu using direct current (DC) magnetron sputtering deposition technique, a typica physical vapor deposition (PVD) method and a bottom-up way to construct various nanostructured metals. High-density twin boundaries (TBs) and nanovoids (NVs) are introduced into two distinct nanostructured Cu films, including nanovoid-nanotwinned (NVNT) Cu (111) and nanovoid (NV) Cu (110). The in-situ high-energy Kr⁺⁺ (1 MeV) and ex-situ low energy He⁺ (< 200 keV) irradiations are subsequently preformed on the as-deposited Cu samples. On the one hand, the in-situ TEM observations suggest that TBs and NVs can influence the formation, distribution and stability of radiation-induced defects. Meanwhile, the preexisting microstructures also undergo structural change through void shrinkage and twin boundary migration. On the other hand, the ex-situ micro-pillar compression tests reveal that the Heirradiated NV-NT Cu contains less defect clusters but experiences more radiation-induced hardening. The underlying mechanisms of void shrinkage, twin boundary migration, and radiationinduced hardening are fully discussed based on post-irradiation analyses and computer simulations.