The bolling film coefficients of sulfur dioxide were obtained from. experiments with an electrically heated wire submerged in a pool of sulfur dioxide liquid. A three-inch 15 Gage Nichrome V wire served as heating element in the boiling process. Electric power consumed by the wire was equal to the amount of heat transferred. Both temperatures of the wire surface and the liquid were recorded by thermocouples for the computation of the boiling film coefficients. The boiling curves of sulfur dioxide in the nucleate boiling region were obtained and plotted for pressures of 50, 60, 70, and 80 psig. The data for plotting the boiling curves are given in detail. A plot of heat flux versus the temperature difference between the boiling liquid sulfur dioxide and the surface of the heating element at different pressures is also presented. Comparisons were made with the limited information available for this boiling region. / Master of Science

The major objective of this thesis was to evaluate electrically the damage caused by a low energy (< 4keV) Ar⁺ bombardment on n-GaAs(100) surfaces. Electrical measurements were performed on Schottlky diodes formed on the virgin and the ion-etched surfaces. The l-V measurements show deterioration of diode parameters by ion etching. The ion etched diodes have a strong component of surface leakage current. The high frequency capacitance of ion-etched diodes is less than that of the virgin diodes. The low frequency capacitance of ion-etched diodes was found to be frequency dispersive. The extent of frequency dispersion diminishes at low temperatures and at low reverse biases. Virgin diode capacitance, on the other hand, was found to be independent of frequency. The electrical characteristics of ion-etched diodes are explained by means of an amorphous layer and a donor-like damaged layer formed as a result of ion etching. The depth of the top amorphous layer increases with etch energy. The damaged layer containing the ion induced traps superimposes over the amorphous layer and extends deep into the bulk semi-conductor. The density of such traps is very bias sensitive and also temperature dependent. A possible equivalent circuit model for the ion-etched material is proposed. Low temperature isochronal annealing (< 450°C, 10mins.) was not found effective in causing complete recovery of the ion-damaged surface. / Master of Science

Fiber optic sensors fabricated from standard silica fibers have many advantages over conventional sensors like small size, portability, durability and immunity to electromagnetic fields. Unfortunately, these sensors are not suitable for use in harsh environments where the temperatures are greater than 700°C and large working stresses are involved. Sapphire fiber-based sensors present an attractive alternative for use in such environments. The material properties of sapphire like high melting point, extreme hardness and relative imperviousness to chemical reactions, coupled with the advantages of optical fiber sensing, enhance the performance of these sensors for rugged use. Unfortunately, commercial sapphire fiber that is currently available has higher optical attenuation than silica fiber and is costlier. 0, it is prudent to use a small length of sapphire fiber as a sensor head, which is then spliced to a standard singlen10de silica fiber which acts a lead-in/lead-out fiber to the sapphire sensor head. This thesis investigates possible splicing techniques to fabricate such a sensor set-up. Comparative results from experiments performed on splices that have been obtained by each of these techniques, are presented. Furthermore, two different sensor configurations using a sapphire fiber, spliced to a silica fiber, are developed, and the results of preliminary tests are presented. / Master of Science

Unlike robots, living creatures are open systems that absorb material from their environment, metabolize it, and shed waste. As a result, they can self-repair, self-sustain, and grow. This dissertation explores a process that allows robots to act similarly, showing the possibility of self-repairing, self-sustaining, and growing “robot organisms.” I study whether robots can absorb and integrate new material, and shed waste. Two novel robot platforms are introduced in the context of this study: the Robot Link, and the Vibrating Particle Robot. The former is a truss-style modular robot platform, while the latter is a particle robot. In this work, I share the hardware designs and build instructions for both robots, and explain relevant parts of the software used to operate the robots. I found that the Robot Link platform is capable of self-assembly, self-repair, and absorbing Robot Links to make itself bigger, faster, or more capable. Further, I demonstrated that three-dimensional robots made from Robot Links can assist in forming other three-dimensional Robot Link structures. The results offer a glimpse of the potential of metabolic machines and introduces them as a path to more adaptable, resilient, and sustainable robots in the future.

A basic physical explanation, a model, and comments on NDE application of the acoustoultrasonic method for composite materials are presented. The basis of this work is a set of experiments where a sending and a receiving piezoelectric transducer were both oriented normal to the surface, at different points, on aluminum plates, various composite plates, and a tapered aluminum plate. Chapter one introduces the purpose and basic idea of the dissertation, while supporting its need. Also, general comments on the AU method are offered. The second chapter offers a literature review of areas pertinent to the dissertation, such as composite materials, wave propagation, ultrasonics, and the AU method. Special emphasis is given to theory which is used later on and past experimental results that are important to the physical understanding of the AU method. The third chapter describes the experimental set-up, procedure, and the ensuing analysis. In the fourth chapter, the experimental results are presented in both a quantitative and qualitative manner. Chapter five furnishes a physical understanding of experimental results based on elasticity solutions, Lamb wave theory, and through-the-thickness-transverse·resonance (TTTR). Computer results are presented for sake of comparison. The sixth chapter discusses modeling and applications of the AU method for composite materials and the seventh chapter states general conclusions. The unique offering of this work is the physical model of the AU method for composite materials, something which has been much needed and sorely lacking. This physical understanding is possible due to the extensive set of experimental measurements, also reported in this dissertation. / Ph. D.

Natural fibers like kenaf, hemp, flax and sisal fiber are becoming alternatives to conventional petroleum fibers for many applications. One such applications is the use of Non-woven bio-fiber mats in the automobile and construction industries. Non-woven hemp fiber mats were used to manufacture plywood in order to optimize the plywood structure. Hemp fiber mats possess strong mechanical properties that comparable to synthetic fibers which include tensile strength and tensile modulus. This study focuses on the use of hemp fiber mat as a core layer in plywood sandwich composite. The optimization of fiber mat plywood was done by performing a three factor experiment. The three factors selected for this experiment were number of hemp mat layers in the core, mat treatment of the hemp mat, and the glue content in the core. From the analysis of all treatments it was determined that single hemp mat had the highest effect on improving the properties of the plywood structure.

No description available.

Alkaline/surfactant/polymer (ASP) flooding is of increasing interest and importance because of high oil prices and the need to increase oil production. The benefits of combining alkali with surfactant are well established. The alkali has very important benefits such as lowering interfacial tension and reducing adsorption of anionic surfactants that decrease costs and make ASP a very attractive enhanced oil recovery method provided the consumption is not too large and the alkali can be propagated at the same rate as a synthetic surfactant and polymer. However, the process is complex so it is important that new candidates for ASP be selected taking into account the numerous chemical reactions that occur in the reservoir. The reaction of acid and alkali to generate soap and its subsequent effect on phase behavior is the most crucial for crude oils containing naphthenic acids. Using numerical models, the process can be designed and optimized to ensure the proper propagation of alkali and effective soap and surfactant concentrations to promote low interfacial tension and a favorable salinity gradient. The first step in this investigation was to determine what geochemical reactions have the most impact on ASP flooding under different reservoir conditions and to quantify the consumption of alkali by different mechanisms. We describe the ASP module of UTCHEM simulator with particular attention to phase behavior and the effect of soap on optimum salinity and solubilization ratio. Several phase behavior measurements for a variety of surfactant formulations and crude oils were successfully modeled. The phase behavior results for sodium carbonate, blends of surfactants with an acidic crude oil followed the conventional Winsor phase transition with significant three-phase regions even at low surfactant concentrations. The solubilization data at different oil concentrations were successfully modeled using Hand's rule. Optimum salinity and solubilization ratio were correlated with soap mole fractions using mixing rules. New ASP corefloods were successfully modeled taking into account the aqueous reactions, alkali/rock interactions, and the phase behavior of soap and surfactant. These corefloods were performed in different sandstone cores with several chemical formulations, crude oils with a wide range of acid numbers, brine with a wide range of salinities, and a wide range of temperatures. 2D and 3D sector model ASP simulations were performed based on field data and design parameters obtained from coreflood history matches. The phenomena modeled included aqueous phase chemical reactions of the alkaline agent and consequent consumption of alkali, the in-situ generation of surfactant by reaction with the acid in the crude, surfactant/soap phase behavior, reduction of surfactant adsorption at high pH, cation exchange with clay, and the effect of co-solvent on phase behavior. Sensitivity simulations on chemical design parameters such as mass of surfactant and uncertain reservoir parameters such as kv/kh ratio were performed to provide insight as the importance of each of these variables in chemical oil recovery. Simulations with different permeability realizations provided the range for chemical oil recoveries. This study showed that it is very important to model both surface active components and their effect on phase behavior when doing mechanistic ASP simulations. The reactions between the alkali and the minerals in the formation depend very much on which alkali is used, the minerals in the formation, and the temperature. This research helped us increase our understanding on the process of ASP flooding. In general, these mechanistic simulations gave insights into the propagation of alkali, soap, and surfactant in the core and aid in future coreflood and field scale ASP designs. / text

Water is becoming increasingly scarce as the demand for fresh water continues to rise. One potential new water resource is purified produced water. Produced water is generated during oil and gas production, and it is often contaminated with emulsified oil, high levels of salt, and particulate matter. Produced water purification using polymer membranes has been investigated, but its implementation is limited by membrane fouling. This study focused on the preparation and application of poly(ethylene glycol) (PEG) hydrogels as fouling-resistant coatings for commercial reverse osmosis (RO) membranes. To prepare fouling-resistant coatings for RO membranes, three series of copolymer hydrogel networks were synthesized using poly(ethylene glycol) diacrylate (PEGDA) as the crosslinker and acrylic acid (AA), 2-hydroxyethyl acrylate (HEA), or poly(ethylene glycol) acrylate (PEGA) as comonomers, and their transport properties were evaluated. The hydrogels have high water uptake and high water permeability, and crosslink density strongly influences water uptake and water permeability. For example, a 100 mol% PEGDA hydrogel contained 61% water by volume, but 80PEGA, which has essentially the same chemical composition but lower crosslink density, contained 72% water by volume. Hydrogel water permeability ranged from 10 to 26 (L [mu]m)/(m² hr bar) and correlates well with water uptake; high water uptake often leads to high water permeability. Additionally, the copolymers have hydrophilic surfaces with a low affinity for oil, based on contact angle measurements using n-decane in water. Commercial RO membranes (AG RO membrane from GE Water and Process Technologies) were coated with PEG hydrogels, and the desalination and fouling resistance properties of the coated membranes were tested. The water flux of coated membranes and a series-resistance model were used to estimate coating thickness; the coatings were approximately 2 [mu]m thick. NaCl rejection for both uncoated and coated membranes was 99.0% or greater. As determined by zeta potential measurements, both uncoated and coated RO membranes are negatively-charged, but coated membranes are less negatively-charged than uncoated RO membranes. Model oil/water emulsions, prepared with either a cationic or an anionic surfactant, were used to probe membrane fouling. In the absence of oil, surfactant charge, and therefore, electrostatic interactions play a significant role in membrane fouling. In the presence of DTAB, a cationic surfactant, the AG RO membrane water flux immediately dropped to 30% of its initial value, but in the presence of SDS, an anionic surfactant, its water flux gradually decreased to 74% of its initial value after 24 hours. However, in both cases, coated membranes exhibited less flux decline than uncoated membranes. Coated membranes also experienced little fouling in the presence of an n-decane/DTAB emulsion. After 24 hours, the water flux of a PEGDA-coated AG RO membrane was 73% of its initial value, while the water flux of an AG RO membrane fell to 26% of its initial value. Conversely, both coated and uncoated membranes fouled significantly in the presence of an n-decane/SDS emulsion, indicating that oil fouling is controlled both by electrostatic and hydrophobic interactions. Overall, this work provides answers to some of the fundamental questions posed regarding the viability of using modified membranes for produced water treatment. / text

Thesis submitted in partial fulfilment of the requirements for the degree Doctor of Technology: Biomedical Technology In the Faculty of Health and Wellness Sciences At the Cape Peninsula University of Technology 2014 / Peroxidases are ubiquitous catalysts that oxidise a wide variety of organic and inorganic compounds employing peroxide as the electron acceptor. They are an important class of oxidative enzymes which are found in nature, where they perform diverse physiological functions. Apart from the white rot fungi, actinomycetes are the only other known source of extracellular peroxidases. In this study, the production of extracellular peroxidase in wild type actinomycete strains was investigated, for the purpose of large-scale production and finding suitable applications. The adjustment of environmental parameters (medium components, pH, temperature and inducers) to optimise extracellular peroxidase production in five different strains was carried out. Five Streptomyces strains isolated from various natural habitats were initially selected for optimisation of their peroxidase production. Streptomyces sp. strain BSII#1 and Streptomyces sp. strain GSIII#1 exhibited the highest peroxidase activities (1.30±0.04 U ml-1 and 0.757±0.01 U ml-1, respectively) in a complex production medium at 37°C and pH 8.0 in both cases. Maximum enzyme production for Streptomyces strain BSII#1 was obtained in the presence of 0.1 mM veratryl alcohol or pyrogallol, while 0.1 mM guaiacol induced the highest peroxidase production in Streptomyces sp. strain GSIII#1. As the highest peroxidase producer, Streptomyces sp. strain BSII#1 was selected for further studies. The strain was first characterised by a polyphasic approach, and was shown to belong to the genus Streptomyces using various chemotaxonomic, genotypic and phenotypic tests. Production of peroxidase was scaled up to larger volumes in different bioreactor formats. The airlift configuration was optimal for peroxidase production, with Streptomyces sp. strain BSII#1 achieving maximum production (4.76±0.46 U ml-1) in the 3 l culture volume within 60 hrs of incubation. A protocol for the purification of the peroxidase was developed, which involved sequential steps of acid and acetone precipitation, as well as ultrafiltration. A purification factor of at least 46-fold was achieved using this method and the protein was further analysed by LC-MS. The protein was shown to be a 46 kDa protein, and further biochemical characterisation showed that the peroxidase had a narrower spectrum of substrates as compared to reports on other peroxidases derived from actinomycetes. With 2,4-dichlorophenol as the substrate, the Km and Vmax for this enzyme were 0.893 mM and 1.081 μmol min-1, respectively. The purified peroxidase was also capable of catalysing coupling reactions between several phenolic monomer pairs. Overall, the peroxidase from Streptomyces sp. strain BSII#1 could feasibly be produced in larger scales and there remains further room to investigate other potential applications for this enzyme.