Thesis (Ph. D.)--University of Texas at Austin, 2002. / Vita. Includes bibliographical references. Available also from UMI Company.

Over the last decade, luminescence measurements have been used primarily to detect and quantify specific organic pollutants and heavy metals, and in a few cases for monitoring microbial activity. In this study, a fiber-optic luminescence detection system was developed to examine the relationship between microbial activity and the resultant impact on biodegradation and transport of substrate in porous media. This system allows rapid, real-time, and non-destructive measurements of in-situ luminescence from a specific lux reporter microbial population in porous media. An understanding of the formation and dynamics of bioactive zones is very important for in-situ bioremediation applications because it is in these zones that the remediation process is optimal. This study also examined the location and size of a biologically active zone in response to changes in local substrate and electron acceptor availability. Results show that when DO was not a limiting factor, the bioactive zone encompassed the entire system. However, as the availability of DO became limiting for the higher-00 experiments, the size of the bioactive zone shrank and was ultimately limited to the proximity of the substrate source. Furthermore, a decrease in the size of the bioactive zone enhanced the rate of substrate biodegradation per unit area. This study also investigated the impact of several coupled factors including substrate concentration, pore-water velocity, and initial cell density on solute biodegradation and transport behavior for a system influenced by three stressors, microbial lag, microbial growth, and cell transport. Results showed that temporal changes in biodegradation potential, and therefore attendant substrate transport behavior, were influenced by microbial lag, growth, dissolved oxygen limitations, and cell elution. As a result, substrate transport behavior was non-steady except for relatively short residencetime conditions wherein substrate degradation exhibited quasi first-order behavior. Cell transport and elution was important, especially under significant growth conditions. Under such conditions, the majority of the cells in the system (60 to 90%) was distributed in the solution phase where most of the biodegradation took place. This study illustrates the complex behavior that can be associated with microbially mediated processes, and which should be included in solute transport models to accurately predict the fate of contaminants in the subsurface environment.

Not available / text

The Standard Penetration Test (SPT) is the most widely used in-situ soil test in the world. "Large Penetration Test" (LPT) is a term used to describe any scaled up version of the SPT. Several types of LPT have been developed around the world for the purpose of characterizing gravel deposits, as SPT blow counts are less reliable in gravels than in sands. Both tests suffer from the lack of a reliable means of determining transferred energy. Further, the use of LPT blow counts is generally limited to calculation of equivalent SPT blow counts using correlation factors measured in sands. Variation of LPT blow counts with grain size is assumed to be negligible. This research shows that safety hammer energies can be reliably estimated from measurements of hammer impact velocity for both SPT and LPT. This approach to determining transferred energy is relatively simple, and avoids the primary limitation of existing methods, which is the inability to calibrate the instrumentation. Transferred energies and hammer impact velocities are collected from various sources. These data are used to determine the ratio between the hammer kinetic energy and the transferred energy (energy transfer ratio, ETR), which is found to follow a roughly Normal distribution for the various hammers represented. An assessment of uncertainty is used to demonstrate that an ETR based approach could be superior to existing energy measurement methods. SPT grain size effects have primarily been characterized as the variation of an empirical relative density correlation factor, (CD)SPT, with mean grain size. In this thesis, equivalent (CD)LPT data are back-calculated from measured SPT-LPT correlation factors (CS/L). Results of a numerical study suggest that SPT and LPT grain size effects should be similar and related to the ratio of the sample size to the mean grain size. Based on this observation, trend-lines with the same shape as the (CD)SPT trend-line are established for the back-calculated (CD)LPT data. A method for generating the grain size effect trend-line for LPT is then proposed. These trend lines provide a rational approach to direct interpretation of LPT data, or to improved prediction of equivalent SPT blow counts.

Mechano-chemical activation is fundamentally different than chemical activation in that energy is added to alter the state of bond energy instead of exciting electrons to produce a chemical reaction. Mechano-chemical activation has demonstrated to alter the chemical reaction and rates. There remains no development of a model to quantify the changes in reactions due to mechano-chemical activation. This research aims in expanding our understanding of the influence of mechanochemical activation methods. The dynamics and kinetics of mechano-chemically activated surfaces will be studied using x-ray spectroscopy methods. Mechano-chemical interactions can be quantified through the study of electron energies. X-ray spectroscopy is a useful method of analyzing and quantifying electron energy states. X-ray absorbance is used to study the valence state electron shells of iron undergone activation through sliding friction of naturally produced wax. In-situ x-ray photoemission spectroscopy is employed to instantaneously characterize single crystal tantalum samples of each principal crystallographic orientation during oxidation. Sliding friction of the naturally produced wax resulted in a reduction in the binding energy of the iron 2p electrons by approximately one electron-volt. This reduction in binding energy is attributed to ferrocene which is an organo-metallic alloy, Fe(C5H5)2. Mechanical strain of the crystal lattices of tantalum resulted in altered activation energies. Activation energy increased with the application of lattice strain. At increasing strain, oxide properties become more dependent on the lattice strain than the crystal orientation and temperature. A model system is developed incorporating mechanical strain into the prediction of activation energy and rates.

The Standard Penetration Test (SPT) is the most widely used in-situ soil test in the world. "Large Penetration Test" (LPT) is a term used to describe any scaled up version of the SPT. Several types of LPT have been developed around the world for the purpose of characterizing gravel deposits, as SPT blow counts are less reliable in gravels than in sands. Both tests suffer from the lack of a reliable means of determining transferred energy. Further, the use of LPT blow counts is generally limited to calculation of equivalent SPT blow counts using correlation factors measured in sands. Variation of LPT blow counts with grain size is assumed to be negligible. This research shows that safety hammer energies can be reliably estimated from measurements of hammer impact velocity for both SPT and LPT. This approach to determining transferred energy is relatively simple, and avoids the primary limitation of existing methods, which is the inability to calibrate the instrumentation. Transferred energies and hammer impact velocities are collected from various sources. These data are used to determine the ratio between the hammer kinetic energy and the transferred energy (energy transfer ratio, ETR), which is found to follow a roughly Normal distribution for the various hammers represented. An assessment of uncertainty is used to demonstrate that an ETR based approach could be superior to existing energy measurement methods. SPT grain size effects have primarily been characterized as the variation of an empirical relative density correlation factor, (CD)SPT, with mean grain size. In this thesis, equivalent (CD)LPT data are back-calculated from measured SPT-LPT correlation factors (CS/L). Results of a numerical study suggest that SPT and LPT grain size effects should be similar and related to the ratio of the sample size to the mean grain size. Based on this observation, trend-lines with the same shape as the (CD)SPT trend-line are established for the back-calculated (CD)LPT data. A method for generating the grain size effect trend-line for LPT is then proposed. These trend lines provide a rational approach to direct interpretation of LPT data, or to improved prediction of equivalent SPT blow counts.

Diss. (sammanfattning) Stockholm : Karol. inst. / Härtill 5 uppsatser.

Thesis (M.Sc.)--University of Adelaide, Dept. of Anatomical Sciences, 2005? / Title from title page of source document; viewed July 19 2005. Bibliography: p. 91-107 of source document. Also available in print and CD-ROM forms.

Thesis (M.S. in environmental engineering)--Washington State University, December 2008. / Title from PDF title page (viewed on Apr. 17, 2009). "Department of Civil and Environmental Engineering." Includes bibliographical references (p. 15-18).

Thesis (Ph. D., Civil Engineering)--University of Idaho, April 2008. / Major professor: Steven Porter. Includes bibliographical references. Also available online (PDF file) by subscription or by purchasing the individual file.