Two studies were conducted to examine the effects of lactose hydrolysis on freezing point and dipping characteristics of ice cream. The overall research objective was to determine changes in freezing point, texture and ease of dipping ice cream as a result of lactose hydrolysis. It was also the goal of this research to relate observations from the sensory dippability study with hardness and yield stress data to determine if the latter methods could be used as an alternative to human testing of dippability. In the first experiment, ice cream mixes were treated with lactase (EC 3.2.1.23) to cause 0 to 83% lactose hydrolysis. Lactose hydrolysis decreased the freezing point from -1.63oC in the control (0% hydrolysis) to -1.74oC in the 83% hydrolyzed sample (p < 0.05). Firmness decreased from 0.35 J in the control sample to 0.08 J in the 83% hydrolyzed sample. Lactose hydrolyzed samples melted at a faster rate than the control. There was a difference (p < 0.05) in ease of dipping between samples treated with lactase and the control. There were no perceived differences in sweetness and coldness. In the second study, ice cream mixes were treated with lactase (EC 3.2.1.23) from the microbial sources Kluyveromyces lactis and Aspergillus oryzae to cause 0 to 100% lactose hydrolysis. Compression measurements and yield stress as measured by the vane method were both affected by the temperature of the samples. R2 values for compression measurements as related to lactose hydrolysis were higher then those obtained for yield stress measurements. Human evaluation determined a difference (p < 0.05) between the control samples (0% hydrolyzed) and the treatment groups (80% and 100% hydrolyzed). This research demonstrated a relationship between lactose hydrolysis and ease of dipping ice cream. The results implied that the effect of lactose hydrolysis on the dipping characteristics could be evaluated successfully by three different methods: the vane method, compression measurements, and human evaluation. Changes in freezing point due to lactose hydrolysis were minimal, implying that monitoring freezing point is not enough to determine textural characteristics. / Master of Science

Over the past centuries, a number of process routes for extraction of metal values from an ore or other resources have been developed. These can generally be classifiedinto pyrometallurgical, hydrometallurgical or electrometallurgical routes. In the caseof the latter two processes, the reaction medium consists of liquid phase electrolytesthat can be aqueous, non-aqueous as well as molten salts. The present dissertationpresents the work carried out with two aspects of the above-mentioned electrolytes.First part is about the electrolyte solutions, which can be used in solvent extractionrelevant to many hydrometallurgical or chemical engineering processes; the secondpart is about the molten salts, which is often used in the electrometallurgical processesfor production of a variety of many kinds of metals or alloys, especially those that arehighly reactive.In the first part of this thesis, the focus is given to the thermodynamics ofelectrolyte solutions. Since the non-ideality of high concentration solution is not wellsolved, a modified three-characteristic-parameter correlation model is proposed,which can calculate the thermodynamic properties of high concentration electrolytesolutions accurately. Model parameters for hundreds of systems are obtained foraqueous as well as non-aqueous solutions. Moreover, a new predictive method tocalculate the freezing point depression, boiling point elevation and vaporizationenthalpy of electrolyte solutions is also proposed. This method has been shown to be agood first approximation for the prediction of these properties.In the second part, a process towards the extraction of metal values from slags,low-grade ores and other oxidic materials such as spent refractories using molten saltsis presented. Firstly, this process is developed for the recovery of Cr, Fe values fromEAF slag as well as chromite ore by using NaCl-KCl salt mixtures in the laboratoryscale. The slags were allowed to react with molten salt mixtures. This extraction stepwas found to be very encouraging in the case of Cr and Fe present in the slags. Byelectrolysis of the molten salt phase, Fe-Cr alloy was found to be deposited on thecathode surface. The method is expected to be applicable even in the case of V, Mnand Mo in the waste slags.Secondly, this process was extended to the extraction of copper/iron from copperore including oxidic and sulfide ores under controlled oxygen partial pressures.Copper or Cu/Fe mixtures could be found on the cathode surface along with theemission of elemental sulphur that was condensed in the cooler regions of the reactor.Thus, the new process offers a potential environmentally friendly process routereducing SO2 emissions.Furthermore, the cyclic voltammetric studies of metal ions(Cr, Fe, Cu, Mg, Mn)in (CaCl2-)NaCl-KCl salt melt were performed to understand the mechanisms, such asthe deposition potential, electrode reactions and diffusion coefficients, etc. In addition,another method using a direct electro-deoxidation concept(FFC Cambridge method),was also investigated for the electrolysis of copper sulfide. Sintered solid porouspellets of copper sulfide Cu2S and Cu2S/FeS were electrolyzed to elemental Cu, S andCu, Fe, S respectively in molten CaCl2-NaCl at 800oC under the protection of Argongas. This direct electrolysis of the sulfide to copper with the emission of elementalsulfur also offers an attractive green process route for the treatment of copper ore. / QC 20100714

abstract: CubeSats are a newly emerging, low-cost, rapid development platform for space exploration research. They are small spacecraft with a mass and volume of up to 12 kg and 12,000 cm3, respectively. To date, CubeSats have only been flown in Low Earth Orbit (LEO), though a large number are currently being designed to be dropped off by a mother ship on Earth escape trajectories intended for Lunar and Martian flyby missions. Advancements in propulsion technologies now enable these spacecraft to achieve capture orbits around the moon and Mars, providing a wealth of scientific data at low-cost. However, the mass, volume and launch constraints of CubeSats severely limit viable propulsion options. We present an innovative propulsion solution using energy generated by onboard photovoltaic panels to electrolyze water, thus producing combustible hydrogen and oxygen for low-thrust applications. Water has a high storage density allowing for sufficient fuel within volume constraints. Its high enthalpy of formation provides more fuel that translates into increased &#8710;V and vastly reduced risk for the launch vehicle. This innovative technology poses significant challenges including the design and operation of electrolyzers at ultra-cold temperatures, the efficient separation of the resultant hydrogen and oxygen gases from liquid water in a microgravity environment, as well as the effective utilization of thrust to produce desired trajectories. Analysis of the gas combustion and flow through the nozzle using both theoretical equations and finite-volume CFD modeling suggests an expected specific impulse of 360 s. Preliminary results from AGI's Satellite Toolkit (STK) indicate that the &#916;V produced by the system for an 8kg CubeSat with 6kg of propellant in a LEO orbit (370 km altitude) is sufficient for an earth escape trajectory, lunar capture orbit or even a Mars capture orbit. These results suggest a promising pathway for an in-depth study supported by laboratory experiments to characterize the strengths and weaknesses of the proposed concept. / Dissertation/Thesis / Masters Thesis Aerospace Engineering 2015

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Effect of architecture at nanoscale on the macroscopic properties of polymer materials has long been a field of major interest, as evidenced by inhomogeneities in networks, multimodal network topologies, etc. The primary purpose of this research is to establish the architecture-property relationship of polymer networks by studying the physical and mechanical responses of a series of topologically different PTHF networks. Monodispersed allyl-terminated PTHF precursors were synthesized through ¡°living¡± cationic polymerization and functional end-capping. Model networks of various crosslink densities and inhomogeneities levels (unimodal, bimodal and clustered) were prepared by endlinking precursors via thiol-ene reaction. Thermal characteristics, i.e., glass transition, melting point, and heat of fusion, of model PTHF networks were investigated as functions of crosslink density and inhomogeneities, which showed different dependence on these two architectural parameters. Study of freezing point depression (FPD) of solvent confined in swollen networks indicated that the size of solvent microcrystals is comparable to the mesh size formed by intercrosslink chains depending on crosslink density and inhomogeneities. Relationship between crystal size and FPD provided a good reflection of the existing architecture facts in the networks. Mechanical responses of elastic chains to uniaxial strains were studied through SANS. Spatial inhomogeneities in bimodal and clustered networks gave rise to ¡°abnormal butterfly patterns¡±, which became more pronounced as elongation ratio increases. Radii of gyration of chains were analyzed at directions parallel and perpendicular to stretching axis. Dependence of Rg on ¦Ë was compared to three rubber elasticity models and the molecular deformation mechanisms for unimodal, bimodal and clustered networks were explored. The thesis focused its last part on the investigation of evolution of free volume distribution of linear polymer (PE) subjected to uniaxial strain at various temperatures using a combination of MD, hard sphere probe method and Voronoi tessellation. Combined effects of temperature and strain on free volume were studied and mechanism of formation of large and ellipsoidal free volume voids was explored.