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    • 3241336.PDF.jpg
    • Thesis

    • Authors: Perez, Natalia (2006)

    • In this study, shear strength and volume change behavior of unsaturated soils is evaluated using axis-translation test methods and advanced testing equipment designed to provide accurate volume change determination during specimen shearing. Tests were performed on a wide range of soil types with net normal stress from 20 to 250 kPa and matric suction from 20 to 700 kPa. This data set adds significantly to the existing database of unsaturated soil properties. The triaxial test data was analyzed using the extended Mohr-Coulomb equation proposed by Fredlund et al (1978). A hyperbolic curve was fit to the (kb versus suction relationship, and a correlation between the hyperbolic curve par...

    • 3210222.PDF.jpg
    • Thesis

    • Authors: Swingley, Wesley Douglas (2006)

    • Since the advent of life on this planet, photosynthetic prokaryotes have evolved to fill a variety of ecological niches. Many organisms have made novel adaptations in light harvesting mechanisms, pigment compositions, and opportunistic metabolic pathways. We set out to study two such organisms, Acaryochloris marina and Roseobacter denitrificans. The marine cyanobacterium A. marina lives in an environment where much of the photosynthetically active light is absorbed by another cyanobacterial species. Consequently, A. marina utilizes the unique pigment chlorophyll (Chi) d to absorb light that is unused by Chl a and b in the competing species. In spite of the lower-energy light absorbed...

    • 3243897.PDF.jpg
    • Thesis

    • Authors: Wang, Hao (2006)

    • Mechanistic and phenomenological models and careful parameter estimations are presented through both aquatic and terrestrial ecosystems. The stoichiometric modeling of the bacteria-algae lake system is relatively new, while the lemming population cycle has attracted the attention of several generations of theoretical and experimental biologists and continues to be an issue of controversy. Bacteria-algae interaction in epilimnion is modeled with explicit consideration of carbon (energy) and phosphorus (nutrient). Global qualitative analysis and bifurcation diagrams of this model are presented. Competition of bacterial strains are modeled to examine Nishimura's hypothesis that in sever...

    • 3241370.PDF.jpg
    • Thesis

    • Authors: Zhao, Zhihe (2006)

    • A key aspect of design and the maintenance of underwater pipelines is the assessment of local scour and its propagation. Scouring around objects placed on a sandy bottom is very complex because it involves two-phase turbulent flows and a myriad of sediment transport modes. This dissertation addresses two principal configurations of scour around pipelines in two parts. First, clear-water scour around a long fixed pipeline placed just above a non-cohesive sandy bed is numerically simulated. Second, live-bed scour around a fixed pipeline and scour below a sagging pipeline are investigated. These two simulations are conducted by using an Eulerian two-phase model that implements Euler-Eule...

    • 3220322.PDF.jpg
    • Thesis

    • Authors: McDonnell, Ryan (2006)

    • A number of organometallic complexes utilize carbamate ligands to incorporate CO2 into new molecules. In order to better understand metal-carbamate chemistry, a series of CO2 reactive alkylaminozinc complexes were synthesized by the addition of dimethylzinc to secondary amines, resulting in the isolation of Zn(CH3)2(HNC4H8O)2, 1. The addition of one equivalent of CO2 to 1 resulted in the formation of the partially converted complex [Zn(CH3,)(HNC4H8O)(02CNC4H8O)]n, 2. Addition of CO2 in excess under anhydrous conditions formed the complex [Zn(02CNC4H8O)2]n, 3, and the addition of one quarter equivalent of H2O to 3 caused the formation of the Zn4(O2CNC4H8O)6 complex, 4. The kinetics of ...