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Novel wine yeast strains have the potential to satisfy customer demand for new sensorial experiences and to ensure that wine producers have strains that can produce wine as efficiently as possible. In this respect, hybrid yeast strains have recently been the subject of intense research, as they are able to combine the favourable characteristics of both parental strains. In this study, two Saccharomyces “Kéknyelű” grape juice isolates were identified by species-specific PCR and PCR-RFLP methods and investigated with respect to their wine fermentation potential. Physiological characterization of the isolated strains was performed and included assessment of ethanol, sulphur dioxide, temperature and glucose (osmotic stress) tolerance, killer-toxin production, glucose fermentation ability at 16 °C and 24 °C, and laboratory-scale fermentation using sterile “Kéknyelű” must. Volatile components of the final product were studied by gas chromatography (GC) and mass spectrometry (MS). One isolate was identified as a S. cerevisiae × S. kudriavzevii hybrid and the other was S. cerevisiae. Both strains were characterized by high ethanol, sulphur dioxide and glucose tolerance, and the S. cerevisiae strain exhibited the killer phenotype. The hybrid isolate showed good glucose fermentation ability and achieved the lowest residual sugar content in wine. The ester production of the hybrid strain was high compared to the control S. cerevisiae starter strain, and this contributed to the fruity aroma of the wine. Both strains have good oenological characteristics, but only the hybrid yeast has the potential for use in wine fermentation.

Over the past years, wire-based direct energy deposition (DED) has been transitioning from rapid prototyping to the production of end-use part and mass production. However, a wide market penetration of the DED has not happened yet. The difficulties for wide-scale market adoption to critical structural components are related to the development cost for process optimization and for manufacturing of high-quality parts. For metallic components, the process conditions (e.g., power, speed, tool path) control the material and mechanical properties/performance of the printed part. The thermal history strongly determines the phase fraction, morphology, growth pattern, size of microstructure, and nature of defects. Thus, in this study, we: 1) developed a thermal simulation using finite element method, 2) experimentally measured thermal histories from a U-shaped part with four tool paths of horizontal, vertical, raster, and contour to calibrate and validate the thermal model, and 3) investigated the effect of thermal history on microstructure evolution and quantified the microstructural variation during the printing process.

The work in this thesis aims to uncover energy loss mechanisms in MEMS-based piezoelectric contour-mode resonators. Quality factors for these devices has been constrained to under 10,000, limiting their commercial applications. The first part of this thesis studies Q degredation related to anchor losses. During fabrication, the outer edge of the anchors are released from the substrate due to an isotropic etch step used in releasing the device from the substrate. This allows both ends of the anchors and the surrounding region of the device layers to undergo strain resulting in energy loss during operation. This study finds that a variation in Q of up to 31% can occur as a result of this released area. A novel method for minimizing this loss through modified boundary conditions is also analyzed and experimentally tested.\par The second part of this thesis develops a new method of measuring ring-downs at ultra high frequencies using laser Doppler vibrometry. Due to an inherently low signal to noise ratio and a 4ns timing error in the vibrometer measurement triggering, traditional ring-down methods are not possible at ultra high frequencies. The method outlined here overcomes this and produces results with an error of less than 6% when compared to electrically determined values.Next, a method is outlined for measuring the magnitudes of the individual material wavelengths on the surface of the resonator. The devices are composed of multiple material layers, each with a unique acoustic velocity. As a result, at resonance, each layer has a unique wavelength that can be measured using laser Doppler vibrometery.The final section combines the previous two methods to measure the ring-downs of the individual material layers used in the construction of the resonators. Due to their unique material properties, the rate at which the vibrations of each material decays can be quantified to determine future fabrication choices.

Yeasts in the lager brewing group are closely related and consequently do not exhibit significant genetic variability. Here, an artificial Saccharomyces cerevisiae × Saccharomyces eubayanus tetraploid interspecies hybrid was created by rare mating, and its ability to sporulate and produce viable gametes was exploited to generate phenotypic diversity. Four spore clones obtained from a single ascus were isolated, and their brewing-relevant phenotypes were assessed. These F1 spore clones were found to differ with respect to fermentation performance under lager brewing conditions (15°C, 15 °Plato), production of volatile aroma compounds, flocculation potential and temperature tolerance. One spore clone, selected for its rapid fermentation and acetate ester production was sporulated to produce an F2 generation, again comprised of four spore clones from a single ascus. Again, phenotypic diversity was introduced. In two of these F2 clones, the fermentation performance was maintained and acetate ester production was improved relative to the F1 parent and the original hybrid strain. Strains also performed well in comparison to a commercial lager yeast strain. Spore clones varied in ploidy and chromosome copy numbers, and faster wort fermentation was observed in strains with a higher ploidy. An F2 spore clone was also subjected to 10 consecutive wort fermentations, and single cells were isolated from the resulting yeast slurry. These isolates also exhibited variable fermentation performance and chromosome copy numbers, highlighting the instability of polyploid interspecific hybrids. These results demonstrate the value of this natural approach to increase the phenotypic diversity of lager brewing yeast strains.