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Collection Description
Collection of student theses and dissertations from as early as 1939, but mainly from 2010 to present.
Pages
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- Water oxidation catalysts with heteroatom pendant bases and instrumentation for quantifying oxygen
- Avid consumption of fossil fuels by humans has led to record high levels of the greenhouse gas carbon dioxide (CO2). An energy storage medium to replace dwindling and finite fossil fuel supplies must be found. Hydrogen gas (H2) is an attractive alternative to hydrocarbon fuels but presently natural gas is the primary feedstock for H2 production globally. Therefore, an alternative process for hydrogen production must be developed. Photoelectrochemical electrolysis of water (H2O) presents a promising method for the clean generation of H2. The oxidation of water to oxygen (O2), four protons (H+), and four electrons (e-) must precede the reduction of H+ to H2 and is the more demanding reaction both kinetically and thermodynamically. Transition metal catalysis can realize this challenging transformation. Careful choice of metal and ligand design can facilitate each stage of the oxidation of water; in particular, the management of H+ during catalysis can help improve both the speed and the durability of the catalyst. This dissertation describes the synthesis, characterization, and water oxidation activity of two new water oxidation catalysts featuring heteroatom H+ relays and the development of instrumentation to better quantify the O2 produced during H2O oxidation. Chapter 2 describes the incorporation of phosphonate monoester and sulfonate and pendant bases into the first coordination sphere of the well-studied water oxidation platform [(2,2';6',2"- terpyridine)(2,2’-bipyridine)Ru(OH2)]2+. The complexes were characterized by combustion analysis, NMR spectroscopy, and x-ray crystallography. The catalytic performance of the complexes was evaluated for water oxidation catalysis using ceric ammonium nitrate (CAN) as a sacrificial oxidant via manometry and by square wave and cyclic voltammetry in a buffered aqueous milieu. The phosphonate monoester was found to perform poorly under chemical oxidation conditions but did show electrocatalytic behavior by cyclic voltammetry. The sulfonate system performed very well with CAN as the oxidant demonstrating a turnover frequency of 0.88 s-1 and turnover number of 7402. The sulfonate system also demonstrated electrocatalytic behavior suggesting homogenous electrocatalysis is maintained. Pourbaix analysis and a computational study suggest the intermediacy of a unprecedented ruthenium (III) oxyl, with the sulfonate acting as a pendant base late in the catalytic cycle. Chapter 3 describes the development of two pieces of instrumentation for the detection of oxygen produced by our water oxidation catalysts. The first instrument is a dual manometry/optical oxygen sensing cell which was constructed for evaluating catalyst performance. Problems with the fluorescent oxygen sensor including drift and sensitivity to humidity led us to focus on pressure as the primary indication of oxygen production. The cell is a robust and easy to use system that provides excellent repeatability and reliability, with <2% drift at more than twice typical operating pressure over 60 h. The second piece of instrumentation was an automated system for sampling headspace gas in a bulk electrolysis (BE) cell. The design and construction of a panel that interfaces a custom BE cell, potentiostat, and gas chromatograph/mass spectrometer (GC/MS) is described., University of California San Diego; San Diego State University
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- Water quality changes during artificial recharge with reclaimed water
- To meet the needs for increased use of reclaimed water and to provide data for regulatory decisions, a 1/2-acre research basin was constructed in the San Gabriel River Coastal spreading grounds to study chemical and microbial processes related to such recharge practices. Hydrologic, chemical, and microbiological data were collected during an artificial recharge experiment between April 4 and June 1 1994, when 12.5 acre-ft of reclaimed water was delivered to the research basin for 17 days. Water samples were collected to determine the changes in concentrations of the major ions, selected trace metals, nutrients, oxygen-18, deuterium, and nitrogen-I 5. The populations of nitrifying, denitrifying, nitrate-reducing, and coliform bacteria were determined from selected water samples collected during the recharge event In addition, core material was collected to determine the lithology, permeability, and cation exchange capacity of the top 10 feet of soil beneath the research basin. The sediment beneath the research basin consists of moderately-sorted, coarse sand with a fine-grained layer extending from about 31 to 37 feet below the bottom of the research basin. The fine-grained layer was confirmed by EM logs and appears to be continuous beneath the research basin. Vertical hydraulic conductivities from permeameter measurements ranged from 55 to 85 ft/day, and can decrease to less than l ft/day. Slug tests yielded a horizontal hydraulic conductivity of approximately 85 ft/day. The initial vertical flux of reclaimed water was 7.02 ft3/day and horizontal flux 236 of groundwater beneath the research basin was 0. 76 ft3/day, suggesting vertical flow dominated during the early stages of the recharge experiment. Total and fecal coliform bacteria populations varied during the recharge experiment from none to >300 cfu/100mL, suggesting the bacteria migrated with the reclaimed water. Nitrogen-transforming bacteria were present in high numbers before and during the recharge experiment. Hydrogen and oxygen isotopes confirm displacement of preexisting water beneath the research basin was rapid and nearly complete, and nitrogen-15 isotopes suggest denitrification was occurring during the recharge experiment. Suboxic conditions suggested by low dissolved oxygen concentrations were present at the start of the experiment. As the reclaimed water percolated beneath the research basin, the conditions became oxic and nitrification of ammonia occurred. After 4 days, suboxic conditions returned and nitrate was removed by denitrification. The study showed the presence of the thin clogging layer composed of fine-grained, organic-rich sediment at the floor of the research basin can exert a strong influence on the infiltration rate. The presence of coliform bacteria exceeded the maximum contaminant level (MCL) during the second day of recharge to a depth of l0 feet. The drinking water MCL was exceeded by nitrite within the research basin and by manganese within the aquifer., San Diego State University
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- Water quality conditions in shallow subsurface waters Imperial Valley, California
- The author has not identified the source of the base map Geographic coordinates are taken from Google Earth. 1:344,800, Two ground water systems were identified in the Imperial Valley, California. The upper system consisted of water in the shallow subsurface. Stable isotopes and tritium showed that the chemical constituents were controlled by evaporative concentration of recent Colorado River water. Chemical analyses showed that concentrations were variable and influenced by the effects of irrigation and evaporation. Redox sensitive elements indicated that oxidizing conditions were present in this upper system. Trace elements important to the study included selenium and arsenic. Concentrations of these two elements appeared to be negatively correlated. Selenium and chloride covaried supporting isotopic data which showed that concentrations were controlled by evaporation and irrigation practices. A uniform regional ground water system was encountered beneath about 30 feet below land surface. Isotopes and tritium showed that evaporative concentration of old (pre 1952) Colorado River water had occurred in some areas. Chemical concentrations were generally lower and less variable which suggested that the deeper system had not evaporated to the extent of surface and irrigation waters. Selenium concentrations were generally lower as a result of sorption onto the soil whereas arsenic concentrations were generally high., San Diego State University
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- Water resources and hydrogeology of the San Onofre Basin, San Diego County, California
- Plate 1 Areal geology of the San Onofre Basin; Plate 2 Cross-section X-X1 San Onofre watershed, San Diego, California; Plate 3 Generalized columner section San Onofre section, San Diego, California; Plate 4 Water wells within San Onofre Basin; Plate 5 Piezometric map, June 1977; Plate 6 Piezometric map, September 1977; Plate 7 Piezometric map, January 1978; Plate 8 Piezometric map, March 1978, The San Onofre Basin of the United States Marine Corps Base at Camp Pendleton, California covers 42.3 square miles and is the northwesternmost watershed in San Diego County. This basin was studied to determine the safe yield potential for producing groundwater. The results were gained through study of general geology and hydrogeologic characteristics of the various rock units within the basin. The study of the geology resulted in identification and mapping of eight geologic formations, in addition to the identification of the major structural and geomorphic features. The hydrogeologic investigation, from a three-phase drilling program, sedimentological research, and well production data indicates two economic aquifer systems within five potential reservoirs. These data permit calculation of a long-term safe yield as well as selection of recommended drilling sites at which maximum economic development of the groundwater resource can take place. The drilling program of small- and large-diameter shallow wells and one deep well indicates that economic quantities of high quality recoverable groundwater is restricted to the San Mateo Sandstone and the alluvial systems. Recharge is primarily from precipitation, with a minor addition of water from two sewage treatment plants. These two aquifers have a storage capacity of approximately 6,850 acre-feet to an arbitrary limiting depth of sea level. The study resulted in recommendations that total water withdrawals from the basin remain below 680 acre-feet per year. The adherence to this safe yield production rate will not result in mining of the groundwater resource or in the degradation of the quality of the groundwater. Sites for future production of water will result in wells which will produce water at rates of at least 1,000 gallons per minute with less than 20 feet of drawdown for extended periods within the recommended safe yield figure. The continued proper watershed management--phreatophyte control, maintenance of spreading structures for artificial recharge, and production limits within safe yield amounts-- will insure the protection of the San Onofre water resources., San Diego State University
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- Water resources of Borrego Valley San Diego County, California
- Base map source is not identified. GPS coordinates for the base map derived from Google Earth satellite images. 1:140,000, Plate 1: Hydrogeological Cross-Sections, The groundwater aquifer system underlying Borrego Valley currently represents the sole source of water to the town of Borrego Springs and the surrounding community for municipal, agricultural and recreational demands. Groundwater has been extracted from the Borrego Valley aquifer since the early part of the 20th century. Beginning in the late 1940's and occurring throughout much of the period of groundwater development in Borrego Valley, groundwater extraction has exceeded natural groundwater recharge, resulting in an apparent overdraft condition. The net depletion of groundwater from storage within the aquifer system was approximately 510,000 acre-feet during the period 1945 through 2000. Overdraft of the aquifer has resulted in a decline of groundwater levels in the majority of monitored wells. Recent monitoring has indicated that water levels are currently declining an average of approximately 2 feet per year. Continued overdraft of the aquifer will inevitably lead to continued decline in groundwater levels, resulting in increasing water costs as water lifts increase and dry wells need to be replaced with successively deeper ones. In addition, continued drawdown of groundwater levels could increase the risk of upconing of deeper poor quality water. The Borrego Valley aquifer system is comprised of four hydrogeologic units of Quaternary and Tertiary age. The uppermost three units are the Quaternary Alluvium, designated as younger, intermediate and older. The oldest and lowermost unit is the Tertiary Palm Spring formation. The hydrogeologic units are underlain by the Cretaceous and older crystalline basement rocks. The Quaternary older alluvium is the principal water-bearing unit of the aquifer. It is relatively coarse grained and is thickest in the northern portion of the basin. Within the alluvium, soil texture is generally coarse grained in the northern portion and along the margins of the basin, where it is closer to the source areas. Soil texture within the alluvium typically grades finer towards the center of the valley at Borrego Sink. Aquifer tests indicate hydraulic conductivity in the older alluvium in the northern portion of Borrego Valley on the order of 300 to 350 feet per day, in the distal portions of the older alluvium in central Borrego Valley at 17 feet per day, and in the relatively shallow portions of the Palm Spring formation in southern Borrego Valley at 10 feet per day. Groundwater in the Borrego Valley appears to be isolated from Lower Borrego Valley. Isolation occurs in southern Borrego Valley due to the thick sequence of Palm Spring formation, which is at or near the surface in the vicinity of Desert Lodge and the Sleepy Hollow folds; and may also be due to the geometry of the basement complex, which is relatively shallow in the area from Yaqui Ridge to Borrego Mountain. The primary source of recharge to the Borrego Valley aquifer is from infiltration of runoff from the several creeks and intermittent streams that drain to the valley from the mountains of the surrounding watershed. This stream recharge has been estimated to have ranged from approximately 600 acre-feet to approximately 26,000 acre-feet annually, and average 3,860 acre-feet per year during the period 1945 through 2000. Bedrock recharge is another important source of recharge to the Borrego Valley aquifer, and is estimated to average nearly 1,800 acre-feet per year. Bedrock recharge occurs as subsurface seepage into the aquifer from the fractured crystalline basement rocks surrounding the basin. Total recharge, calculated as the sum of stream and bedrock recharge, is highly variable, ranging from approximately 600 acre-feet in 1975 to approximately 46,000 acre-feet in 1980, a range of almost two full orders of magnitude within a time period of only 5 years. Total recharge to the Borrego Valley aquifer has been estimated to average 5,670 acre-feet per year. Estimates of irrigation return flow were made by applying the chloride mass balance technique to soil samples collected from a citrus orchard and a golf course fairway. An estimated 22 percent of applied irrigation water in citrus orchards is returned to groundwater, while an estimated 14 percent of water applied to golf courses returns to groundwater. Other irrigation in the Valley is assumed to return at the 14 percent rate measured for golf courses. Net total groundwater extraction from the Borrego Valley aquifer was estimated based on well production records, where available, and depicted land use from aerial photographs. Net total groundwater extraction is estimated to have ranged from approximately 100 acre-feet in 1945 to approximately 17 ,000 acre-feet in 1959. Net total groundwater extraction was estimated at 15,300 acre-feet in 2000. A net water budget was calculated as the difference between total recharge and net total groundwater extraction. Groundwater extraction has exceeded recharge in all but the wettest years since 1947, averaging an overdraft of approximately 4, 100 acre-feet per year during the period 1945 to 2000. For the year 2000, the net overdraft was estimated at approximately 12,800 acre-feet., San Diego State University
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- Water, culture and environmental health: Understanding community based planning to improve health outcomes in vulnerable populations
- Background: Previous research suggests that rural water infrastructure investments in developing countries may be expensive, culturally inappropriate and do not result in clean water being consumed at the household level. Interventions and planning that incorporate community-based planning approaches with a careful consideration of cultural and historical connections may be the most effective method of implementing successful improved water projects. Objective: This dissertation examined the outcomes, cultural challenges and successes of water infrastructure projects in two indigenous communities of Baja California, Mexico and developed a low-cost method of assessing rural water systems to improve targeted outcomes of water system improvements. Methods: Both quantitative and qualitative data from a longitudinal study and focus groups were obtained. Survey data regarding health and water practices, along with water samples in each community were collected before and after new water systems were installed and gastrointestinal illness rates calculated. Transcripts from focus groups conducted after the new infrastructure was implemented were examined for cultural attitudes and beliefs towards water use. Field observations from both communities were used to develop a low-cost assessment tool with a scoring method for determining vulnerabilities in water systems. Results: After receiving new water infrastructure in both communities, neither saw a reduction in rates of gastrointestinal illness. Household point-of-use water quality was still poor despite new infrastructure. One of the two communities receiving new water systems did not accept their new system. Cultural significance of the previously used water source was likely the most significant reason for non-acceptance. Conducting a thorough assessment of each point of the communities' water systems using the low-cost indicator method developed could have provided a better assessment of vulnerabilities in the systems and a better approach to intervention. Discussion: This work provides support for incorporating community participation into the planning and implementation of water improvements, and stresses the importance in addition of examining water beliefs and practices.. Poor water quality at point of use underscores the importance of measuring this water quality indicator. Meaningful inclusion of communities can be used to inform approaches to community development that simultaneously take into account community perspectives as well as technical capacity.
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- Waterpipe smoking among Arab American women in San Diego, California
- Arab Americans are one of the country's fastest growing immigrant populations. Arab American adult females emigrate from countries where smoking rates are two to three times higher than the United States national average smoking rate of 21.2%. Studies have shown that smoking rates in Arab Americans are among the highest in the United States. A popular form of tobacco use among Arab Americans, especially Arab American women, is waterpipe smoking. There is paucity of published research conducted on the health behaviors and tobacco use of Arab American women. The aim of this study is to determine predictors of waterpipe use level among Arab American women in San Diego, California. On the basis of previous studies with findings relevant to our research, we hypothesized that after controlling for demographic background factors, regular waterpipe smoking, versus occasional waterpipe smoking, is positively associated with smoking a waterpipe at home, smoking a waterpipe with one close friend, and initiating waterpipe smoking at an early age. Regular waterpipe smoking was defined as smoking a waterpipe at least once a month. This thesis conducts secondary analyses of existing data on 176 Arab American female waterpipe smokers to investigate contingencies theoretically responsible for their waterpipe smoking levels. Predictors were selected based on the Behavioral Ecological Model (BEM). Self-administered surveys were developed at the Center for Behavioral Epidemiology and Community Health (C-BEACH). The female participants of the study were between the ages of 18 to 80 years, with an average of 29 years of age (SD = 13). After controlling for demographic background factors, findings from the logistic regression analysis showed that regular waterpipe smoking was positively associated with smoking a waterpipe at home (P =.010), smoking a waterpipe with one close friend (P = .003), and initiating waterpipe smoking at an early age (P = .023). These predictors will help identify points of intervention to help design tailored health promotion, education, and prevention programs for waterpipe smoking among Arab American women.
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- Wax Without Honey: The LP as Post-WWII American Zeitgeist
- Includes bibliographical references (pages 50-51)., This thesis explores the importance of a sound-reproduction medium - the Long Playing phonograph disc. I place this technology within the context of the zeitgeist that led to its American popularity in the years immediately following the Second World War. I show in this thesis that it was not simply a coincidence that the LP flourished during this time, but actually inevitability. The LP was the medium that best embodied and facilitated the ideals--and perhaps most importantly, the desires--of Americans in the mid-century. Additionally, I posit that the LP was not a result of a time, place, and people, but rather an expression of that time, place, and people. This thesis is a unique--if humble--contribution to the fields of Cultural Studies, Sound Studies, and Complexity Studies. Though I do explore some of the mechanical aspects of the LP and its network of associated technology, my thesis is not an exhaustive technical history or exploration of mid-century sound-reproduction technology. Instead, I posit that the LP was the most effective mid-century medium for representing post-war Americans, and that by examining why this is true, we can better understand another time and culture, as well as our own. I examine hi-fi technology, music genres especially associated with the LP like exotica and space music, and social rituals surrounding these phenomena. Throughout my thesis I point to an assemblage of technology, desire, space, and humanity that constitute what we call the post-WWII era. By seeing how the assemblage works as a whole, we can locate and reflect upon past understandings of space, difference, and desire. In doing so, we can aim to find recurring patterns, and perhaps better understand what informs our own lives today. I have chosen one medium of particular importance to a time, place, and people in my thesis to achieve this.
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- We can probably laugh about this: Playing with theories of humor
- This thesis provides answers for two questions, the first being “what is humor?” and the second being “how can humor be valuable?”. The first part of the thesis determines what a theory of humor should contain while addressing concerns that deal with the subjectivity of humor. The second part examines four major theories of humor: the Incongruity Theory, the Superiority Theory, the Relief Theory, and the Play Theory. The examination includes assessing the necessary and sufficient conditions of what constitutes humor under each theory and raising objections that render each theory inadequate in specific circumstances. Lastly, this thesis argues for the Play Theory and proposes a change to the theory in the third part to avoid objections. The third part also ends by arguing for the value of humor and claims that the value of humor is not limited to one specific type of humor., San Diego State University