Concrete is the most widely used man-made material in the world. Its versatility, strength, and relative ease of construction allow it to be used in the majority of civil infrastructure. However, concrete production plays a significant role in greenhouse gas emissions, accounting for around 8% of CO2 emissions worldwide. This thesis aims to reduce the demand for cement in concrete construction, thus reducing the carbon footprint of the concrete, by focusing on classifying and determining the effectiveness of seven different quarry by-products as partial replacements of cement. Several methods were utilized in this study to characterize the quarry by-products: particle size distribution, helium pycnometry, X-Ray diffraction, X-Ray fluorescence, scanning electron microscopy, and a modified ASTM C1897 Method A that utilizes isothermal calorimetry and thermogravimetric analysis. These various methods allowed for the determination of the physical properties (e.g., gradation, specific gravity, and morphology) and the chemical properties (e.g., mineralogy and reactivity in a cementitious system). The quarry by-products were classified as four granites, two limestones, and one greenstone. These quarry by-products were found to be non-pozzolanic and non-hydraulic. However, there are indications that there may be reactions with the various clays and feldspars in the quarry by-products with calcium hydroxide, which suggests a degree of reactivity that is not necessarily pozzolanic or hydraulic. / Master of Science / Concrete is the most widely used man-made material in the world. Its versatility, strength, and relative ease of construction allow it to be used in the majority of civil infrastructure. However, concrete production plays a significant role in greenhouse gas emissions, accounting for around 8% of CO2 emissions worldwide. This thesis aims to reduce the demand for cement in concrete construction, thus reducing the carbon footprint of the concrete, by focusing on classifying and determining the effectiveness of seven different quarry by-products as partial replacements of cement. Several methods were utilized in this study to determine the physical properties (e.g., gradation, specific gravity, and morphology) and the chemical properties (e.g., mineralogy and reactivity in a cementitious solution) of the materials. The quarry by-products were classified as four granites, two limestones, and one greenstone. In general, these quarry by-products were not found to be reactive as a supplementary cementitious material, although the data may suggest some degree of reactivity between calcium hydroxide and the clays and/or feldspars in the quarry by-products.

<p dir="ltr">Hemorrhage and aortic aneurysms result from external or internal damage to a vessel wall and can be lethal if timely interventions are not made. Blood clotting and thrombus sometimes have a negative connotation in the medical community, but the coagulation cascade is a vital response to hemorrhage and disease. For hemorrhage, the coagulation cascade forms a plug at the injury site providing potentially life-saving hemostasis. In aortic aneurysms, blood coagulates inside the vessel or vessel wall to form intraluminal or intramural thrombus. The role of intraluminal and intramural thrombus in aneurysm rupture remains poorly understood, but past research suggests it may protect against further vessel damage dependent on its location and time of deposition. My dissertation focuses on application of a new photocurable sealant that surrounds a wound and aids in the coagulation cascade during hemorrhage, and analysis of the intramural and intraluminal thrombus that forms in aortic dissections and abdominal aortic aneurysms, respectively. We used volumetric and pulsed-wave Doppler ultrasound to detect changes in hemodynamics, vessel morphology, aneurysm thrombus deposition, and tracked the photocurable sealant’s performance and degradation <i>in vivo</i>. We used novel scanning electron microscopy analysis techniques in aortic aneurysm studies to uncover and quantify new information about thrombus structure. Our characterization and <i>in vivo </i>feasibility study with the photocurable sealant can serve as evidence for translation to future use in humans, and our techniques and findings in murine aneurysm models can potentially be used to elucidate the role and structure of thrombus in human aortic aneurysms.</p>

Nanoindentation is one of the most widespread methods to measure the mechanical performance of complex materials systems. As it allows for local characterization of composite architectures with sub-micron spatial features and a large range of properties, nanoindentation is commonly used to measure the properties of biological materials. In situ nanoindentation, a further development of the approach, is a powerful tool for the analysis of plastic deformation and failure of materials. Here, samples can be mechanically manipulated using the indenter, while their behavior is monitored with the resolution of a scanning electron microscope (SEM). Indeed, numerous studies demonstrate the potential of this approach for studying the most fundamental material characteristics. However, so far, these measurements are performed in high-vacuum conditions inherent to the conventional electron microscopy method, which are irrelevant when studying biological structures that evolved to perform in hydrated conditions. In this work, the ability to conduct nanoindentation experiments under controlled humidity and temperature inside an environmental SEM is developed. This technique has the potential to become crucial for materials design and characterization in many domains where humidity has a significant impact on performance. These include organic/polymer systems, microelectronic and optoelectronic devices, materials for catalysis, batteries, and many more.

It was found that laser modified wood surfaces can be bonded together to create a wood composite without the need of any additive. This bonding method removes the need of applying adhesive, potentially lowers cost, and eliminates off gassing of petroleum resins, creating a wood product with many eco-friendly attributes. This body of work outlines a) initial chemical analysis of the laser modified surface b) its bond strength and c) the optimization of factors that control the strength of the bond. Surface chemical analysis on laser modified wood was conducted using photo acoustic Fourier transform infrared spectroscopy (PA-FTIR) and X-Ray photoelectron spectroscopy (XPS). Light microscopy and scanning electron microscopy were utilized for surface topology analysis.Differential scanning calorimetry (DSC) quantified the thermal properties of the modified wood surface. Screening of multiple factors that would contribute to surface modification and adhesion was performed utilizing mechanical testing. Optimization of significant factors that affect bond strength was determined statistically utilizing a design of experiment approach. Chemical analysis of the laser modified surface revealed changes in the carbonyl and aromatic regions indicating modification of the hemicellulose and lignin components, intensifying with increasing laser modification.The C1/C2 ratios found via XPS revealed that one or more of the following is occurring: more extractives have moved to the surface, condensation reactions among lignin units, and the loss of methoxy and breakage of aryl ether linkages occurred.Microscopy images showed color changes to a darker caramel color with a smoothing of surface topology, suggesting the occurrence of the softening and/or melting of wood polymers. DSC verified chemical and/or physical changes in the wood with the modified material now having a glass transition temperature between 130-150°C.DOE found that laser parameters (power and focus) as well as hot press parameters (temperature and pressure) were significant in optimizing the bond. The impact of the study is the first documentation of the ability to laser modifies wood surfaces and subsequently bond them together. The ability of the wood polymers at the surface to undergo flow at elevated temperature is implicated in the adhesion mechanism of the laser modified wood. / Master of Science

This thesis describes the development and use of a computer-automated microscopy routine for characterization of respirable dust particles from coal mines. Respirable dust in underground coal mining environments has long been known to pose an occupational health hazard for miners. Typically following years of exposure, coal workers' pneumoconiosis (CWP) and silicosis are the most common disease diagnoses. Although dramatic reductions in CWP and silicosis cases were achieved across the US between about 1970-1999 through a combination of regulatory dust exposure limits, improved ventilation and dust abatement practices, a resurgence in disease incidence has been noted more recently – particularly in parts of Appalachia. To shed light on this alarming trend and allow for better understanding of the role of respirable dust in development of disease, more must be learned about the specific characteristics of dust particles and occupational exposures. This work first sought to develop an automated routine for the characterization of respirable dust using scanning electron microscopy with energy dispersive x-ray (SEM-EDX). SEM-EDX is a powerful tool that allows determination of the size, shape, and chemistry of individual particles, but manual operation of the instrument is very time consuming and has the potential to introduce user bias. The automated method developed here provides for much more efficient analysis – with a data capture rate that is typically 25 times faster than that of the manual method on which it was based – and also eliminates bias between users. Moreover, due to its efficiency and broader coverage of a dust sample, it allows for characterization of a larger and more representative number of particles per sample. The routine was verified using respirable dust samples generated from known materials commonly observed in underground coal mines in the central Appalachian region, as well as field samples collected in this region. This effort demonstrated that particles between about 1-9μm were accurately classified with respect to defined chemical categories, and suggested that analysis of 500 particles across a large area of a sample filter generally provides representative results. The automated SEM-EDX routine was then used to characterize a total of 210 respirable dust samples collected in eight Appalachian coal mines. The mines were located in three distinct regions (i.e., northern, mid-central and south-central Appalachia), which differed in terms of primary mining method, coal seam thickness and mining height, and coal and/or rock mineralogy. Results were analyzed to determine whether number distributions of particle size, aspect ratio, and chemistry classification vary between and within distinct mine regions, and by general sampling location categories (i.e., intake, feeder, production, return). Key findings include: 1) Northern Appalachian mines have relatively higher fractions of coal, carbonate, and heavy mineral particles than the two central Appalachian regions, whereas central Appalachian mines have higher fractions of quartz and alumino-silicate particles. 2) Central Appalachian mines tended to have more mine-to-mine variations in size, shape, and chemistry distributions than northern Appalachian mines. 3) With respect to particle size, samples collected in locations in the production and return categories have the highest percentages of very small particles (i.e., 0.94-2.0μm), followed by the feeder and then the intake locations. 4) With respect to particle shape, samples collected in locations in the production and return categories have higher fractions of particles with moderate (i.e., length is 1.5 to 3x width) to relatively high aspect ratios (i.e., length is greater than 3x width) compared to feeder and intake samples. 5) Samples with relatively high fractions of alumino-silicates have higher fractions of particles with moderate aspect ratios than samples with low alumino-silicate fractions. 6) Samples with relatively high fractions of quartz particles have higher fractions of particles with moderate aspect ratios and higher percentages of very small particles than samples with no identified quartz particles. 7) Samples with high fractions of carbonates have higher percentages of particles with relatively low aspect ratios (i.e., length and width are similar) than samples with no identified carbonate particles. / Master of Science / This thesis describes the development and use of a computer-automated microscopy routine for characterization of respirable dust particles from coal mines. Overexposure to respirable dust has long been known to pose an occupational health hazard for miners, leading to the development of lung diseases such as coal workers’ pneumoconiosis (CWP, commonly called “black lung”) and silicosis. Incidence of such diseases amongst US coal miners declined for many years following regulation and development of mining best practices. However, a recent resurgence in disease incidence, particularly in parts of Appalachia, demonstrates a real need for greater understanding of the respirable dust in underground coal mines. This work first sought to develop an automated routine for characterizing coal mine dust using scanning electron microscopy with energy dispersive x-ray (SEM-EDX). SEM-EDX is a powerful tool that allows the size, shape and chemistry of individual particles to be determined. The developed routine is not only much faster than an analogous manual method, but it also reduces the possibility of user bias and provides for more representative results by examining more particles across a wider area of a sample. The method was verified using laboratorygenerated dust samples from known materials commonly observed in underground coal mines, as well as field samples collected in central Appalachia. This effort indicated that the method produces accurate and representative results. Next, the automated SEM-EDX method was used to scan 210 respirable dust samples. These were collected in eight mines in three different regions of Appalachia (i.e., northern, midcentral and south-central Appalachia), which differed by primary mining method, coal seam thickness and mining height, and coal and/or rock mineralogy. Results were analyzed to determine whether particle size, shape, and chemistry number distributions vary between and within distinct mine regions, and by general sampling location categories (i.e., intake, feeder, production, return). Key findings include: 1) Northern Appalachian mines have relatively higher fractions of coal, carbonate, and heavy mineral particles than the two central Appalachian regions, whereas central Appalachian mines have higher fractions of quartz and alumino-silicate particles. 2) Central Appalachian mines tended to have more mine-to-mine variations in size, shape, and chemistry distributions than northern Appalachian mines. 3) With respect to particle size, samples collected in locations in the production and return categories have the highest percentages of very small particles (i.e., 0.94-2.0μm), followed by the feeder and then the intake locations. 4) With respect to particle shape, samples collected in locations in the production and return categories have higher fractions of particles with moderate (i.e., length is 1.5 to 3x width) to relatively high aspect ratios (i.e., length is greater than 3x width) compared to feeder and intake samples. 5) Samples with relatively high fractions of alumino-silicates have higher fractions of particles with moderate aspect ratios than samples with low alumino-silicate fractions. 6) Samples with relatively high fractions of quartz particles have higher fractions of particles with moderate aspect ratios and higher percentages of very small particles than samples with no identified quartz particles. 7) Samples with high fractions of carbonates have higher percentages of particles with relatively low aspect ratios (i.e., length and width are similar) than samples with no identified carbonate particles.

Compression of coated pellets is a practical alternative to capsule filling. The current practice is to add cushioning agents to minimize the stress on the coated pellets. Cushioning agents however add bulkiness and reduce the overall drug loading capacity. In this study, we investigated the performance of compressed coated pellets with no cushioning agent to evaluate the feasibility of predicting the coat behaviour using thermo-mechanical and rheological analysis techniques. Different coating formulations were made of ethyl cellulose (EC) as a coating polymer and two different kinds of additives were incorporated into the polymeric coating solution. Triethyl Citrate (TEC) and Polyethylene glycol 400(PEG400) were used as plasticizers at different levels to the coating formulations (10%, 20%, 30%). Thermal, mechanical and rheological measurements of the coating film formulations were achieved to investigate the effect of plasticizers. Thermal gravimetric analysis results (TGA) showed higher residual moisture content in films plasticised with PEG 400 compared to their TEC counterparts. Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and Parallel Plate Shear Rheometer (PPSR) were used to study the influence of the level and type of plasticisers incorporated in coating film formulation on the performance of the coating film. In this study, both DSC and DMA were used to investigate the Tg for each film coating formulation in order to evaluate the effect of the additives. In general DMA results for the Tg value of the films were always higher by 10-20% than those measured by the DSC. Furthermore, clamp size and the frequency of the oscillation have an influence on the evaluation of Tg. Complex viscosity for different coating film formulations revealed that the shear hinning gradient changes with temperature and plasticiser type and concentration. The value of complex viscosity from DMA and PPSR exhibits power law behaviour. The rheological moduli were indirectly affected by the level of plasticiser. There was a discrepancy between the complex viscosity results obtained from both DMA and PPSR at similar temperature but they follow the same trend. The non plasticized polymer showed a 10 time higher complex viscosity values when measured by DMA over that measured by PPSR. The difference was smaller in plasticized films but it was not consistent. Therefore a consistent coefficient to correlate the DMA and PPSR couldn’t be accurately determined Coated pellets were compressed and key process parameters were evaluated. The obtained results revealed that the coating thickness has a significant effect on the release profile of the final products. It was found that by increasing the coating film thickness, the percentage released decreased. Also the compression force has lower influence on the drug release profile, while the dwell time has very low effect on the percentage release from the final products. Optimum release profile was obtained at a coating level of 5.5% w/w and a compression force of 4700N In conclusion, the elasticity of the plasticised EC films in this study meant that the internal stress is not dissipated during compression and the dwell time range that was used in this experiment. Increasing the thickness therefore was necessary to enhance the strength of the film and avoid cracking. The mechanical and rheological profiling was helpful therefore to understand the behaviour of the coated pellets and predict the film properties at various steps of the process of coating and compression (i.e., various shear rate regimes). Experimental design approach to studying the key process and formulation parameters helped identify the optimum values for the process.

Die strukturelle Charakterisierung im Nano- und Mikrometerbereich ist unerlässlich, da die Materialstruktur eng mit den makroskopischen Eigenschaften verbunden ist. Die vierdimensionale Rastertransmissionselektronenmikroskopie (4DSTEM) ist für diese Charakterisierung gut geeignet. Bei 4DSTEM wird ein konvergenter Elektronenstrahl über eine elektronentransparente Probe gerastert, während ein pixelierter Detektor an jeder Rasterposition ein Transmissionselektronenbeugungsbild aufnimmt. Die Analyse der in diesen Bildern kodierten Information erlaubt die Kartierung der Kristallorientierung, Kristallinität und weiteren Probeneigenschaften. 4DSTEM wird typischerweise in Rastertransmissionselektronenmikroskopen (STEMs) mit Elektronenergien von 60 keV bis 300 keV eingesetzt. Rasterelektronenmikroskope (SEMs) werden hingegen meist für die Oberflächenanalyse verwendet und nutzen Elektronenenergien bis 30 keV. 4DSTEM kann auch in SEMs integriert werden, indem ein pixelierter Detektor unter der elektronentransparenten Probe platziert wird. Während 4DSTEM in STEM eine sub-Ångström-Auflösung und die Durchstrahlung dickerer Proben ermöglicht, stellt 4DSTEM-in-SEM eine preiswertere und verfügbarere Alternative mit größerem Rastersichtfeld dar. Wir haben 4DSTEM-in-SEM in einem regulären SEM mithilfe einer szintillatorbasierten fasergekoppelten Kamera und einem Timepix3 hybriden Pixeldetektor (HPD) realisiert. Deren Kombination mit motorisierten Probentischen ermöglichte uns die Probe relativ zum Elektronenstrahl des SEMs zu bewegen und zu kippen, was die Probenkontrolle in STEMs widerspiegelt. Zur Demonstration des Potenzials von 4DSTEM-in-SEM, haben wir ein komplettes TEM-Netzchen sowie eine C60/MoS₂-van-der-Waals-Heterostruktur kartiert. Außerdem ermöglichte uns der datengesteuerte Modus des Timepix3 HPD eine Datenaufnahme mit mehr als 500k Bildern pro Sekunde, was der Verweilzeit von ringförmig integrierenden STEM-Detektoren ähnelt während das gesamte Beugungsbild aufgenommen wird. / Nano- and micro-scale structural characterization is essential for understanding, predicting, and optimizing the properties of materials since the material's structure is closely linked to its macroscopic properties. Four dimensional scanning transmission electron microscopy (4DSTEM) is well suited for this characterization. In 4DSTEM, a convergent electron beam is rastered over an electron-transparent sample, while a pixelated detector records a transmission diffraction pattern at each raster position. The encoded structural information in these patterns can be analyzed to map sample properties like crystal orientation, grain size, crystallinity, and more. 4DSTEM is typically employed in scanning transmission electron microscopes (STEMs) operating at electron energies of 60 keV to 300 keV. Scanning electron microscopes (SEMs) are widely used for surface morphology analysis operating at electron energies up to 30 keV. 4DSTEM can also be implemented in SEMs by placing a pixelated detector beneath the electron-transparent sample. While 4DSTEM in STEM achieves sub-Ångström spatial resolution and transmits through thicker samples, 4DSTEM-in-SEM offers a cost-effective and accessible alternative with a larger scan field of view while still transmitting through samples tens of nanometers thick. We implemented 4DSTEM-in-SEM using a standard SEM equipped with a custom scintillator-based fiber-coupled camera and a Timepix3 hybrid pixel detector (HPD). The combination of these detectors with motorized sample stages allowed us to move and tilt the sample relative to the SEM's electron beam mirroring the sample control in STEM. To demonstrate the potential of 4DSTEM-in-SEM, we mapped an entire TEM grid and analyzed a C60/MoS₂ van der Waals heterostructure. Additionally, the Timepix3 HPD's data-driven mode enabled acquisition speeds exceeding 500k frames per second, achieving dwell times comparable to annular integrating STEM detectors while recording the full diffraction patterns.

To design high pressure fuel system components that resist wear and scuffing failure when operated in low viscosity fuels, a comprehensive study on the tribological performance of various existing coating materials is necessary. This thesis aims to provide the relative performance of a variety of coating materials across different fuel environments by testing them in conditions that model those experienced in fuel pumps. The relative performance of these coatings are then indexed across a variety of material properties, including hardness, elastic modulus, wettability, and the interaction between the surface and the various types of fuel molecules.

La reconstruction en deux étapes par expanseur et implant est la technique la plus répandue pour la reconstruction mammmaire post mastectomie. La formation d’une capsule périprothétique est une réponse physiologique universelle à tout corps étranger présent dans le corps humain; par contre, la formation d’une capsule pathologique mène souvent à des complications et par conséquent à des résultats esthétiques sous-optimaux. Le microscope électronique à balayage (MEB) est un outil puissant qui permet d’effectuer une évaluation sans pareille de la topographie ultrastructurelle de spécimens. Le premier objectif de cette thèse est de comparer le MEB conventionnel (Hi-Vac) à une technologie plus récente, soit le MEB environnemental (ESEM), afin de déterminer si cette dernière mène à une évaluation supérieure des tissus capsulaires du sein. Le deuxième objectif est d‘appliquer la modalité de MEB supérieure et d’étudier les modifications ultrastructurelles des capsules périprothétiques chez les femmes subissant différents protocoles d’expansion de tissus dans le contexte de reconstruction mammaire prothétique. Deux études prospectives ont été réalisées afin de répondre à nos objectifs de recherche. Dix patientes ont été incluses dans la première, et 48 dans la seconde. La modalité Hi-Vac s’est avérée supérieure pour l’analyse compréhensive de tissus capsulaires mammaires. En employant le mode Hi-Vac dans notre protocole de recherche établi, un relief 3-D plus prononcé à été observé autour des expanseurs BIOCELL® dans le groupe d’approche d’intervention retardée (6 semaines). Des changements significatifs n’ont pas été observés au niveau des capsules SILTEX® dans les groupes d’approche d’intervention précoce (2 semaines) ni retardée. / Two-stage implant-based (expander to implant) breast reconstruction is the most frequently applied technique following total mastectomy. While the periprosthetic capsule is a normal physiologic response to any foreign body, pathological capsule formation often leads complications and suboptimal aesthetic results. The scanning electron microscope (SEM) is a powerful tool that offers unparalleled assessment of capsule ultrastructural topography. The first research aim was to compare conventional high-vacuum (Hi-Vac) SEM with newer environmental scanning electron microscopy (ESEM) technology to determine whether the latter offers superior assessment of breast capsular tissue. The second aim was to apply the most optimal SEM mode to study periprosthetic capsule ultrastructural modifications in women undergoing differing expansion protocols during the first stage of implant-based reconstruction. Ten patients were prospectively included in the first study and 48 prospectively included into the second. Conventional Hi-Vac mode was deemed superior for the comprehensive analysis of breast capsular tissue. Using Hi-Vac mode within the established study protocol, a more pronounced capsular 3-D relief was observed around BIOCELL® expanders when the first postoperative saline inflation took place at 6 weeks following expander insertion (delayed approach). No significant changes were observed with SILTEX® expander capsules in both early (2 weeks) and delayed approach groups.

Thesis deals with environmental scanning electron microscopy and with detection of signal electrons by using ionization detector. First part talks about the principle of environmental scanning electron microscope. Second part describes signals generated by interaction of primary electron beam with sample. Third section explains the principle of impact ionization and ionization detector. Experimental part deals with usage of segmental ionization detector and with measuring of signal amplification from copper and platinum. Thesis also examines arrangement of electrodes of ionisation detector on material contrast and examines also on influence of voltage contrast on base - emitter junction of an NPN bipolar transistor. All experiments were carried out in dependency on saturated water vapour pressure in sample chamber.