No description available.

The use of selective laser melting for AlSi10Mg has been gaining a lot of popularity, but unfortunately, there are a great deal of issues surrounding internal porosity. Hot isostatic pressing (HIP) has been used in many instances alongside a standard T6 treatment to reduce porosity, but that typically involves water quenching. The application for this project is meant for the satellite industry, which has tight dimensional tolerances and as such, water quenching is not adequate. Currently, annealing for a stress relief treatment is the only post- processing measure that does not involve water quenching. This project studied a novel direct HIP approach, whereby an argon quench is used after solution annealing. Three different cooling rates were studied within the DHIP process (DHIP-L=50°C/min, DHIP- M=200°C/min, and DHIP-H=400°C/min) and compared to specimens that were stress relieved (SR). Uniaxial tensile testing revealed that the strength and ductility of DHIP-H outperformed the SR condition. The true stress/strain results showed that all DHIP conditions had a superior true strain and true stress at fracture. All DHIP conditions and SR showed evidence of void growth and coalescence. SR fracture is driven through crack initiation, while the DHIP conditions fracture is driven through localized necking. In-situ tensile tests via scanning electron microscopy coupled with μ-DIC revealed that the DHIP conditions feature damage due to particle fracture, while the SR condition experiences strain localization along the interface of Si particles and the α-Al phase. In-situ tensile testing via XCT studied a comparative analysis between DHIP-M and SR and revealed that DHIP-M experiences more void growth and nucleation than the SR condition. / Thesis / Master of Applied Science (MASc)

Optimal print parameters for additively manufacturing 316L stainless steel using selective laser melting (SLM) at Cal Poly had previously been identified. In order to further support the viability of the current settings, tensile material characteristics were needed. Furthermore, reliable performance of the as-printed material had to be demonstrated. Any influence on the static performance of parts in the as-printed condition inherent to the SLM manufacturing process itself needed to be identified. Tensile testing was conducted to determine the properties of material in the as-printed condition. So as to have confidence in the experimental results, other investigations were also conducted to validate previous assumptions. Stereological relative density measurements showed that the as-printed material exhibited relative density in excess of 99%. Optical dimensional analysis found that the as-printed tensile specimens met ASTM E8 dimensional requirements in 14 out of 15 parts inspected. Baseline tensile tests indicated that the yield stress of the as-printed material is 24% higher than a cold-rolled alternative, while still achieving comparable ductility. The location of a tensile specimen on the build plate during the print was not found to have a significant effect on its mechanical properties. Theoretical behavior of notched tensile specimens based on finite element models matched experimental behavior in the actual specimens. Unique fracture behavior was found in both the unnotched reference and the most severe notch after microscopic inspection, and a root cause was proposed. Finally, extrapolating from previous studies and observing that experimental results matched theoretical models, it was determined that features inherent to SLM parts were not detrimental to the static performance of the as-printed material.

4’ -ester analogues of resveratrol were synthesized using reaction conditions developed to produce mono-ester products in the presence of two other unprotected phenols. Basic conditions were employed to deprotonate the most acidic 4’ phenol followed by addition of anhydrides or acid chlorides to give the ester product. The reaction favored 4’-ester formation in polar aprotic solvents with DMSO being the optimal solvent. (—)-Englerin A is a guaiane-type sesquiterpene containing two ester side chains. Mimics of (—)-englerin A were proposed that retained the ester side chains while replacing the non-polar core with less complicated structures. These proposed mimic cores would maintain the three-dimensional positioning of the esters which are responsible for the anti-cancer activity of (—)-englerin A. Three mimics were synthesized using the bicyclic terpenes borneol and fenchol. Installation of the second ester on the terpene core was accomplished throught the development and optimization of a unique methylene oxidation using chromium trioxide in glacial acetic acid. These mimics were screened against two kidney cancer cell lines. The compounds were shown to have IC50 (inhibitory concentration for 50 % of cells) values above 30 µM.

No description available.

Electric field gradient focusing (EFGF) utilizes a hydrodynamic flow and an electric field gradient to focus and concentrate charged analytes and order them in a separation channel according to electrophoretic mobility. Elution can be achieved by decreasing the applied voltage or increasing the hydrodynamic flow. EFGF has the advantages of concentrating a large volume (100 micro-L) of target proteins without significant band broadening and simultaneously removing unwanted components from the sample. Two types of EFGF devices have been investigated to concentrate and separate proteins: a fiber-based EFGF device and a hydrogel-based EFGF device. Using fiber-based EFGF with UV detection, a concentration factor as high as 15,000 and a concentration limit of detection as low as 30 pM were achieved using bovine serum albumin as a model protein. I also demonstrated the potential of using fiber-based EFGF for quantitative protein analysis. Simultaneous desalting and protein concentration as well as online concentration of ferritin and simultaneous removal of albumin from a sample matrix were also performed using this fiber-based EFGF system. In the approach of utilizing hydrogel-based EFGF, online concentration of amyloglucosidase indicated a concentration limit of detection of approximately 20 ng/mL (200 pM) from a sample volume of 100 micro-L. Both voltage-controlled and flow-controlled elution methods were demonstrated using a 3-component protein mixture. Concentration of human α1-acid glycoprotein with simultaneous removal of human serum albumin was also described. A tandem EFGF system, which integrates fiber-based and hydrogel-based EFGF sections, was also investigated to selectively concentrate and separate proteins in a mixture. By carefully controlling the voltages applied to both sections, charged analytes with high mobilities were trapped in the fiber-based section, analytes with intermediate mobilities in the hydrogel-based section, and analytes with low mobilities not at all. A 3-way switching valve was incorporated in the system to purge the analytes with high mobilities periodically. Selective concentration and separation of myoglobin from a mixture were performed using the tandem EFGF system. Based on the experimental results described in this dissertation, EFGF shows potential for selective isolation, concentration, and quantitation of trace analytes such as proteins in biomedical samples.

<p>In this research, we have studied the interaction between femtosecond laser and dielectric material, especially borosilicate glass, and its applications. Using laser direct writing (LDW), optical fiber sensors and selective metallization of glass surface were explored. For ultrafine selective metallization, supersonic spray deposition system was introduced combining to femtosecond laser direct writing.</p>

No description available.

Bakom Rubrikerna (Behind the headlines) is a project that uses visual communication and the idea of negative space to critique Swedish media, politicians, and the discourse regarding refugees with different backgrounds (cultural, geographical, socioeconomical, religious, political) and ethnicities. It explores the concept of selective sympathy and what role media, especially newsprints, have in recreating harmful narratives around certain refugees. The project aims to give the reader a deeper understanding of the harmful Eurocentric and xenophobic views that influence refugee politics and media’s coverage of the two different refugee (human) crises, in 2015 and today, in 2022.

The market is in great need of more environmentally friendly alternatives to fossil-based composite materials to obtain a more sustainable future. Lignin is the second most common biopolymer and is a byproduct in the pulping and paper industry. Fractionation of lignin has made it possible to receive lignin with narrow dispersity and low molecular weight, which is suitable for further applications. Modification of lignin structure yields new reactive sites that can be tailored for specific needs. Because of the aromatic structure of lignin, it is a promising renewable resource for production of thermosets. In this project Kraft lignin is sequentially solvent-fractionated and modified in an allylation process with allyl chloride. The allylated lignin is reacted with a cross-linking agent and used to impregnate carbon fibre mats. The resin-coated material is then cured at 125 oC to achieve a composite material. The project also encompasses characterization of the chemical structure of lignin in the different fractions. The morphology and adhesive properties of the lignin as well as the carbon fibres and the composite material was investigated. Although the production of composite material from lignin and carbon fibres were accomplished, bubble formation in the resin was a problem for all composite samples that were prepared, whether it was during solvent evaporation or during curing. By performing the addition of resin to carbon fibre mats in multiple steps, where pressure is added after the first applied layer, it is suggested that complete adhesion to the carbon fibre can be achieved, whilst maintaining adequate resin to carbon fibre ratio. / Marknaden är i stort behov av mer miljövänliga alternativ till fossilbaserade kompositmaterial för att kunna erhålla en mer hållbar framtid. Lignin är den näst vanligaste aromatiska biopolymeren och framställs som en biprodukt i pappersindustrin. Fraktionering av lignin har gjort det möjligt att erhålla lignin med låg dispersitet och molekylvikt vilket är lämpligt för vidare applikationer. Modifiering av lignins struktur ger upphov till nya reaktiva grupper som kan anpassas för ens behov. Den aromatiska strukturen som lignin besitter resulterar i en lovande förnybar resurs för produktion av härdplast. I detta projekt är Kraft lignin sekventiellt fraktionerat med lösningsmedel och modifierat med hjälp av en allyleringsprocess i närvaro av allylklorid. Det allylerade ligninet reagerar med en tvärbindare och används vidare för att impregnera kolfiber. De impregnerade kolfibermattorna härdades i ugn vid 125 oC för att erhålla kompositmaterial. Projektet omfattar även karaktärisering av den kemiska strukturen i lignin från de olika fraktionerna. Morfologin och vidhäftningsförmåga av lignin, kolfiber och likaså kompositmaterialet undersöktes. Ett kompositmaterial bestående av kolfiber och lignin erhölls med framgång under projektets gång, dock var bubbelbildning ett stort problem under förångningen av lösningsmedel och även under härdningsprocessen. Addition av harts till kolfibermattorna i flera steg, där tryck är adderat efter det första lagret har blivit applicerat, anses vara en lovande metod för att en hög vidhäftningsgrad ska kunna erhållas. Detta medan ett adekvat förhållande mellan harts och kolfiber upprätthålls.