The word "Prion" refers to self-perpetuating protein aggregates that cause neurodegenerative diseases in mammals. It is a protein isoform that has undergone a conformational change which converts the normal form of the protein into the infectious form with the same amino acid sequence. Yeast [PSI+] prion is the prion isoform of Sup35 protein, a translation termination factor eRF3. It has been suggested that prion [PSI+] is controlled by the ensemble of chaperones with Hsp104 playing the major role. The previous work performed in the Chernoffs lab showed that the defective GET pathway caused by get led to the defect in [PSI+] curing by excess Hsp104. The GET pathway is a system responsible for transporting newly synthesized TA-protein to the ER membrane, and the components which have been proven to be involved in this pathway include: Get1, Get2, Get3, Get4, Get5 and Sgt2. In this study we describe the mechanism underlying the effect of the defective GET pathway on [PSI+]. We demonstrate that Sgt2, one of the components of GET pathway, interacts with Sup35 in both [PSI+] and [psi-] strains through its prion domain. Overproduction of Sgt2 and Hsp70-Ssa is triggered by the defective GET pathway and leads to the protection of [PSI+] aggregates from curing by excess Hsp104. We show that the direct interaction between Sgt2 and Hsp70-Ssa is not required for this protective effect.

The influence of supplementary materials such as slag, metakaolin and limestone in steam-cured ternary and quaternary cement blends on physical and chemical hydration mechanisms was studied by analyzing the evolution of non-evaporable water content, hydration products and compressive strength. The role of limestone in hydration reactions of cement was also investigated. These properties were studied through the use of differential thermal and thermogravimetric analyses, as well as the loss-on-ignition, X-ray diffraction and compressive strength tests at 1, 3, 7, and 28 days. Research findings revealed that it is possible to replace up to 40% cement with other materials and still achieve compressive strengths similar to mixtures with a 25% cement replacement at 0.34 w/b ratio. Additionally, ternary limestone mixtures exhibited superior mechanical properties to ternary metakaolin mixtures. Lastly, limestone powder was determined to behave as inert filler, accelerating hydration at early ages through heterogeneous nucleation.

The influence of supplementary materials such as slag, metakaolin and limestone in steam-cured ternary and quaternary cement blends on physical and chemical hydration mechanisms was studied by analyzing the evolution of non-evaporable water content, hydration products and compressive strength. The role of limestone in hydration reactions of cement was also investigated. These properties were studied through the use of differential thermal and thermogravimetric analyses, as well as the loss-on-ignition, X-ray diffraction and compressive strength tests at 1, 3, 7, and 28 days. Research findings revealed that it is possible to replace up to 40% cement with other materials and still achieve compressive strengths similar to mixtures with a 25% cement replacement at 0.34 w/b ratio. Additionally, ternary limestone mixtures exhibited superior mechanical properties to ternary metakaolin mixtures. Lastly, limestone powder was determined to behave as inert filler, accelerating hydration at early ages through heterogeneous nucleation.

Joints represent a design challenge, especially for composite structures. Among the available joining methods, co-curing is an efficient way to integrate parts for some applications. Coates and Armanios have proposed a Single Nested Overlap (SNO) co-cured joint configuration, obtained from a single lap joint through the overlap/interleafing of the adjoining top/bottom adherend plies, respectively. Through a comparative investigation, they have demonstrated joint strength and fatigue life improvements over the single lap joint counterparts for unidirectional and quasi-isotropic adherend lay-ups. This research extends the comparative investigation of Coates and Armanios by focusing upon characterizing and differentiating the damage initiation and progression mechanisms under quasi-static loading. Six specimen configurations are manufactured and tested. It is confirmed that single nested overlap joints show 29.2% and 27.4% average improvement in strength over single lap counterparts for zero-degree unidirectional and quasi-isotropic lay-ups, respectively. Several nondestructive evaluation techniques are used to observe and analyze damage initiation, damage progression and failure modes of the studied specimens and to monitor their mechanical response. Using X-ray Radiography and Optical Microscopy techniques during quasi-static loading, a physical characterization of damage and failure mechanisms is obtained. The acoustic emission data acquired during monotonic loading could reveal the overall picture of AE activities produced by the damage initiation, development and accumulation mechanisms within the specimen via parametric analysis. Further AE analysis by a selected supervised clustering method is carried out and shown successful in differentiating and clustering the AE data. Correlation with physical observations from other techniques suggests that the resulting clusters may be associated to specific damage modes and failure mechanisms.

This multi-scale investigation aimed to provide new knowledge and understanding of creep and shrinkage of high performance lightweight concrete (HPLC) by assessing prestress losses in HPLC prestressed members in a large-scale study; by quantifying the effect of the constituent materials and external conditions on creep and shrinkage in a medium-scale study; and by improving the fundamental understanding of creep and shrinkage in a small-scale study. Creep plus shrinkage prestress losses were between two and eight times lower than those estimated for the design standards and approximately 50% of those measured in similar strength normal weight high performance concrete girders. The lower creep and shrinkage exhibited by HPLC was found to be caused by a synergy between the pre-soaked lightweight aggregate and the low water-to-cementitious material ratio matrix. That is, the water contained in the lightweight aggregate contributes to enhance hydration by providing an internal moist curing. The water in the aggregate also contributes to maintain a high internal relative humidity which reduces or eliminates autogenous shrinkage. This higher internal relative humidity also reduces creep by preventing load-induced water migration. Finally, lightweight aggregate exhibits a better elastic compatibility with the paste than normal weight aggregate. This improved elastic matching and the enhanced hydration are believed to reduce peak deformations at the ITZ which further decreases creep and shrinkage.

Focused Ion Beam (FIB) has several advantages such as high sensitivity, high material removal rates, low forward scattering and directing fabrication. Without any etched mask, processing time can be reduced. Pyrex glass etched by FIB is used for fast fabrication of 3-D submicron structure mold. In this study, glass is used as substrate. The UV-cured resin that spin-coated onto a mold has 3-D structure patterns. 3-D structure patterns are transferred on the plate to investigate the effects of parameters of UV cured, pressure and exposure time on the occurrence of defects. The relationship of these processing parameters for the imprinting process is also realized. Besides, the material property of UV-cured resin is investigated. UV-Cured resin is investigated by thermogravimetric Analysis (TGA) to measure the degradation temperature (Td). The hardness and modulus of UV-Cured resin was measured by nanoindentation to realize deformed ability of material for the imprinting process. Moreover, the contact angle of Pyrex glass is measured to investigate its surface quality for the imprint process.

ABSTRACT EFFECTS OF POZZOLAN INCORPORATION AND CURING CONDITIONS ON STRENGTH AND WATER RESISTANCE OF NATURAL GYPSUM PASTES Cengiz, Okan Ph.D., Department of Civil Engineering Supervisor : Prof. Dr. Turhan Y. Erdogan September 2009, 189 pages There are large reserves of gypsum rock (CaSO4&middot / 2H2O) in Turkey and in various regions of the world. Heating gypsum rock to 140 - 190 0C causes it to lose three-fourths of its water molecules and turn into gypsum, called plaster of Paris / heat application over 190 0C results in loss of all the water molecules and this form of the material is called gypsum anhydrite. When gypsum is mixed with water, it gains cementitious property and hardens in a short time. Therefore, natural gypsum anhydrite and especially plaster of Paris are widely used in the construction industry. On the other hand, its not being water resistant and having low strength restrict the use of gypsum products for outdoor applications. In this study, the effects of pozzolan incorporation to natural gypsum pastes and application of various curing regimes for improving their water resistance and strength were investigated. Compressive strength and absorption tests on one thousand one hundred twenty two 5-cm cube specimens produced from v 13 different mixture types were conducted. Also the microstructures of these products were investigated using the analytical technique X-Ray Diffraction. The test results showed that water resistance and strength properties of pozzolan-incorporated gypsum products were improved. Curing of the product at elevated temperature regimes was an additional factor that contributed to this improvement. It was concluded that the natural gypsum mixtures prepared and cured at the above-mentioned conditions could also be used for outdoor applications. Keywords: Pozzolan, Natural Gypsum, Elevated Temperature Curing

<p>This work describes how a fatty acid methyl ester (FAME) derived from a vegetable oil can be introduced as reactive diluent in a solvent-borne thermally cured coil-coating system. The evaluated reactive diluent, rape seed methyl ester (RME), has been evaluated both in a fully formulated clear coat system and via model studies.</p><p>A reactive diluent is a compound that acts as a solvent in the liquid paint, lowering the viscosity, and chemically reacts into the final film during cure. Introduction of a reactive diluent derived from vegetable oil give a more environmental compliant coating since a renewable material is incorporated in the coating and the amount of traditional solvent can be decreased. These positive environmental factors have increased the industrial interest.</p><p>The fully formulated clear coat studies describes how addition of reactive diluent affects rheological properties of the wet paint, film formation, incorporation, and final film properties in a hydroxyl-functional polyester/melamine coil-coating system. The coating were cured under industrial coil-coating cure conditions and analyzed with Raman, carbon-14 dating, extraction, dynamic mechanical analysis, and visually observed. Viscosity measurement of the wet paint show that RME works as a diluent. RME increase the mobility in the system enhancing the film formation process and occurrence of defect-free films. The incorporation of RME could not be confirmed by Raman analysis. However, carbon-14 dating did indicate the presence of RME that could not be extracted from the films. The appearance and mechanical properties of the films were also significantly affected by addition of RME. Dynamic mechanical analysis of the free standing films showed that the final film properties were affected by oven temperature, choice of co-solvent, and flash-off period.</p><p>Model studies were performed to further clarify how RME chemically can react through transesterification with the hydroxyl-groups of the polyester. RME and its two main components methyl oleate and methyl linoleate were reacted with primary alcohols with and without tertiary hydrogen both under low temperature (110, 130, 150, 170°C) and industrial cure conditions. The transesterification reaction was monitored with 1H-NMR and real time IR. Evaporation and side reactions, e.g. oxidation, are competing factors with the transesterification reaction. The fatty acid structure affects the conversion as a higher amount of unsaturations triggers higher degree of oxidation. The study also showed that reaction time and temperature affects the transesterification conversion, degree of side reactions, and catalyst choice.</p>

Semiconductor nanocrystal-based photovoltaics are an interesting new technology with the potential to achieve high efficiencies at low cost. CuInSe2 nanocrystals have been synthesized in solution using arrested precipitation and dispersed in solvent to form a “solar ink”. The inks have been deposited under ambient conditions to fabricate photovoltaic devices with efficiency up to 3%. Despite the low cost spray coating deposition technique, device efficiencies remain too low for commercialization. Higher efficiencies up to 7% have been achieved using a high temperature selenization process, but this process is too expensive. New nanocrystal film treatment processes are necessary which can improve the device efficiency at low cost. To this end, CuInSe2 nanocrystals were synthesized using a diphenyl phosphine:Se precursor which allows for precise control over the nanocrystal size. The size is controlled by changing the temperature of the reaction. The smallest size nanocrystals demonstrated extremely high device open circuit voltage. Ligand exchange procedures were used to replace the insulating oleylamine capping ligand used during synthesis with more conductive halide ions or inorganic chalcogenidometallate cluster (ChaM) ligands. These ligands led to improved charge transport in the nanocrystal films. A high-intensity pulsed light processing technique known as photonic curing was used which allows for high temperature sintering of nanocrystal films on temperature-sensitive substrates. High energy pulses cause the nanocrystals to sinter into large grains, primarily through melting and resolidification. The choice of metal back contact has a dramatic effect on the final film morphology, with Au and MoSe2 back contacts providing much better adhesion with the CuInSe2 than Mo back contacts. Nanocrystal sintering without melting can be achieved by replacing the oleylamine ligands with ChaM ligands prior to photonic curing. Low energy photonic curing pulses vaporize the oleylamine ligands without inducing sintering or grain growth. This greatly improved nanocrystal coupling and interparticle charge transport. Multiexcitons were successfully extracted from these nanocrystal films and external quantum efficiencies over 100% were observed. Transient absorption spectroscopy was used to study the multiexciton generation process in CuInSe2 nanocrystal films and colloidal suspensions. The multiexciton generation efficiency, threshold, and Auger lifetimes for CuInSe2 compare well with other nanocrystal materials. / text

Cellulose-based materials are widely used in a number of important applications (e.g. paper, wood, textiles). Additional developments are suggested by the growing interest for natural fibre-based composite and nanocomposite materials. The motivation is not only in the economic and ecological benefits, but is also related to advantageous properties and characteristics. The objective of this thesis is to provide a better understanding of process-structure-property relationships in some novel cellulose network materials with advanced functionalities, and showing potential large-scale processability. An important result is the favourable combination of mechanical properties observed for network-based cellulose materials. Compression-moulding of cellulose pulp fibres under high pressure (45 MPa) and elevated temperature (120 – 180 oC) provides an environmentally friendly process for preparation of stiff and strong cellulose composite plates. The structure of these materials is characterized at multiple scales (molecular, supra-molecular and microscale). These observations are related to measured reduction in water retention ability and improvement in mechanical properties. In a second part, cellulose nanofibrils (NFC) are functionalized with in-situ precipitated magnetic nanoparticles and formed into dense nanocomposite materials with high inorganic content. The precipitation conditions influence particle size distributions, which in turn affect the magnetic properties of the material. Besides, the decorated NFC network provides high stiffness, strength and toughness to materials with very high nanoparticle loading (up to 50 vol.%). Subsequently, a method for impregnation of wet NFC network templates with a thermosetting epoxy resin is developed, enabling the preparation of well-dispersed epoxy-NFC nanocomposites with high ductility and moisture durable mechanical properties. Furthermore, cellulose fibrils interact positively with the epoxy during curing (covalent bond formation and accelerated curing). Potential large scale development of epoxy-NFC and magnetic nanocomposites is further demonstrated with the manufacturing of 3D shaped compression-moulded objects. Finally, the wet impregnation route developed for epoxy is adapted to prepare UV-curable NFC nanocomposite films with a hyperbranched polymer matrix. Different chemical modifications are applied to the NFC in order to obtain moisture durable oxygen barrier properties. / <p>QC 20131111</p>