Browsing by Subject "water"
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Item A Computational Study of the Role of Hydration in the Assembly of Collagen and Other Bio laments(2012-10-19) Mayuram Ravikumar, KrishnakumarHydration is known to be crucial in biomolecular interactions including ligand binding and self-assembly. In our earlier studies we have shown the key role of water in stabilizing the specific parts of the collagen triple helix depending on the imino acid content. We further showed that the primary hydration shell around collagen could act as a lubricating layer aiding in collagen assembly. But key details on the structure and dynamics of water near protein surfaces and its role in protein-protein interactions remain unclear. In the current study we have developed a novel method to analyze hydration maps around peptides at 1-A resolution around three self-assembling lament systems with known structures, that respectively have hydrated (collagen), dry non-polar and dry polar (amyloid) interfaces. Using computer simulations, we calculate local hydration maps and hydration forces. We find that the primary hydration shells are formed all over the surface, regardless of the types of the underlying amino acids. The weakly oscillating hydration force arises from coalescence and depletion of hydration shells as two laments approach, whereas local water diffusion, orientation, or hydrogen bonding events have no direct effect. Hydration forces between hydrated, polar, and non-polar interfaces differ in the amplitude and phase of the oscillation relative to the equilibrium surface separation. Therefore, water-mediated interactions between these protein surfaces ranging in character from ?hydrophobic? to ?hydrophilic,? have a common molecular origin based on the robustly formed hydration shells, which is likely applicable to a broad range of biomolecular assemblies whose interfacial geometry is similar in length scale to those of the present study. In a related study through simulations we show that the rate of tissue optical clearing by chemical agents correlated with the preferential formation of hydrogen bond bridges between agent and collagen. Hydrogen bond bridge formation disrupts the collagen hydration layer and facilitates replacement by a chemical agent to destabilize the tertiary structure of collagens thereby reducing light scattering. This study suggests that the clearing ability of an alcohol not only depends on its molecular size, but also on the position of hydroxyl groups on its backbone.Item Assessing the Effectiveness of Water Quality Best Management Practices for Grazing-Lands(2013-12-10) Clary, Calvin RussellBest management practices (BMPs) aim to reduce bacterial loading caused by grazing cattle. Relatively little is known about the effectiveness of alternative shade, alternative water, rip-rap, and prescribed grazing as potential BMPs. Prescribed grazing evaluated how stocking rate affected bacterial loading. E. coli concentrations in runoff samples were compared between plots with various stocking rates. GPS collars were used to determine how a shade pavilion, water source, or rip-rap effected cattle distribution within a stream and riparian pasture by comparing time cattle spent at a location before and after implementing the BMPs. While plots were stocked or within 14 days of being destocked, E. coli concentrations were significantly higher than destocked pastures. No significant differences were observed between E. coli concentrations in runoff from heavily stocked, moderately stocked, or non-grazed pastures when pastures had been destocked for greater than 14 days. On average, the shade structure reduced cattle's dependence on riparian shade by 30%. The alternative water BMP did not reduce the amount of time cattle spent within the riparian zone; however, the study was limited to one trial. Riparian rip-rap trials were inconclusive; however, preliminary rip-rap trials showed 20 to 40 cm diameter rip-rap was effective at modifying cattle trough preference. Advances in microbial source tracking, specifically Bacteroides, have allowed better identification of bacterial sources. However, genetic variability within some Bacteroides sequences may undermine the accuracy of these molecular markers. Localized gene-copy curves were created from 12 bovine fecal samples from a single herd, and qPCR assays were used to determine if they better correlated Bacteroides and E. coli populations. Sequences were pyro-sequenced to see if mismatches occurred within primer/probe regions. Base-pair mismatches occurred, and affected qPCR efficiencies. Fecal pollution load estimations were overestimated by using sequences with more mismatches. Genetic diversity was observed within samples from all locations, and indicated genetic variability within Bacteroides populations occurs within a single location as much as between locations. Thus, creating standard curves for individual watersheds would not necessarily improve pollution load estimations.Item Deficit Irrigation Programs for Water Conservation in the Management of Bermudagrass Fairways in Texas(2014-04-29) Hejl, Reagan WesleyGolf course water use in Texas has become increasingly regulated in the past decade due to persistent drought conditions, diminishing water supplies, and rapidly a growing population. Many golf courses have been faced with considerable cutbacks in irrigation allocations, but information is limited regarding critical levels needed for maintaining adequate turf quality, persistence, and recovery from divots and traffic. Furthermore, the effects of irrigation water quality on minimal irrigation requirements has not been fully resolved. A series of field and greenhouse studies were conducted over the course of two years in College Station, TX, to determine the effects of continuous reference evapotranspiration (ET_(o))- based deficit irrigation levels on quality of bermudagrass fairway turf. Turf quality evaluations from both seasons showed that in the absence of traffic, irrigation levels of 0.3 x ET_(o) were sufficient to maintain acceptable turfgrass quality during summer months (at a 3-day per week irrigation frequency). Canopy temperatures increased considerably as irrigation was reduced; with up to a 20? increase detected between irrigated and unirrigated plots. Upon resumption of full irrigation levels in September, unirrigated and deficit-irrigated plots quickly recovered to ~90% green cover within 8 weeks in year 1. However, unirrigated plots were much slower to recover in the second season, only reaching ~30% green cover by 8 weeks. The delayed ability of unirrigated plots to rebound following successive years without irrigation suggests a cumulative effect of drought stress on bermudagrass health and vigor. Traffic treatments delayed recovery across all irrigation levels. Greenhouse investigations into irrigation water quality (reverse osmosis (RO), saline, and sodic) and plant growth regulator trinexapac-ethyl (TE) effects on bermudagrass evapotranspiraton and tolerance to deficit irrigation were also undertaken. Irrigation water quality failed to significantly influence minimal irrigation requirements, but turf irrigated with sodic irrigation did exhibit considerably higher evapotranspiration (ET) rates relative to those receiving saline or RO irrigation. TE improved bermudagrass quality and delayed leaf firing under the soil moisture stress from deficit irrigation. The findings from this research provide timely and practical information for turf managers who must increasingly utilize ET-based irrigation scheduling and/or low-quality water sources in the management of golf course turfgrass systems.Item The effect of nutrient limitations on the production of extracellular polymeric substances by drinking-water bacteria(2013-05) Evans, Ashley Nichole; Kirisits, Mary JoBiological filtration (biofiltration) of drinking-water is gaining popularity due the potential for biodegradation of an array of contaminants not removed by traditional drinking-water processes. However, previous research has suggested that biomass growth on biofilter media may lead to increased headloss, and thus, greater energy and water requirements for backwashing. Research has suggested that the main cause of headloss might be due to extracellular polymeric substances (EPS) rather than the bacterial cells themselves. As EPS production has been shown to increase under nitrogen- and phosphorus-limited or -depleted conditions, the goal of this research was to add to the body of knowledge regarding biofiltration by studying the relationship between EPS production and nutrient limitations in drinking-water. Batch experiments with a synthetic groundwater were run with a mixed community of drinking-water bacteria under nutrient-balanced (a molar carbon to nitrogen to phosphorus ratio [C:N:P] of 100:10:1), nutrient-limited (e.g., C:N:P of 100:10:0.1), and nutrient-depleted conditions (C:N:P of 100:0:1 or 100:10:0). After 5 days, growth was measured as the optical density at 600 nanometers (OD600), and the concentrations of free and bound carbohydrates and proteins, the main components of EPS, were measured. In batch experiments with 2.0 and 0.2 g/L as carbon (mixture of acetic acid, mannitol and sucrose) increases in EPS production per OD600 and decreases in growth were noted under nutrient-depleted conditions. When the same experiments were conducted with a pure culture of Bacillus cereus, bound polysaccharides normalized to OD600 increased under nitrogen- and phosphorus-depleted conditions. Since previous research suggested that Bradyrhizobium would be an important player in EPS production in drinking-water biofilters, similar batch experiments were conducted with Bradyrhizobium. However, due to experimental challenges with Bradyrhizobium japonicum USDA 110, differences in EPS production under nutrient limitations could not be reliably assessed. Additional work is required with Bradyrhizobium. Recommendations for future work include the replication of these batch conditions in steady-state chemostats containing biofilm attachment media and in bench-scale columns. Additionally, future work should include experiments at carbon concentrations as low as 2 mg/L to match typical carbon concentrations in drinking-water biofilters.Item Flooding Experiments with Steam and Water in a Large Diameter Vertical Tube(2010-10-12) Williams, Susan NicoleAn experimental study on flooding with steam and water in a large diameter vertical tube was conducted. This research has been performed to provide a better prediction of flooding in a pressurized water reactor (PWR) pressurizer surge line to be used in reactor safety codes. Experiments were conducted using a 3-inch (76.2 mm) diameter tube 72 inches (1.83 m) long with subcooled water and super-heated steam at atmospheric pressure as the working fluids. Water flows down the inside walls of the tube as an annulus while the steam flows upward in the middle. The water flow rates ranged from 3.5 to 12 gallons per minute (GPM) (0.00022 to 0.00076 m^3/s) and the water inlet temperature was approximately 70 degrees C. The steam inlet temperature was approximately 110 degrees C. The size of the test section as well as the flow ranges of the working fluids was determined based on a scaling analysis of a PWR pressurizer surge line. Two distinct trends were observed in the data. It was found that for water flow rates below 6 GPM (0.00038 m3/s) the amount of steam required for flooding to occur decreases with an increasing water flow rate. For water flow rates above 6 GPM the amount of steam required for flooding to occur increases with an increasing water flow rate. In addition, axial water temperature data was collected. Axial water temperatures have not been recorded in previous flooding experiments with steam and water. A new correlation for predicting flooding with steam and water was proposed. This correlation was an improvement from previous correlations because it included the amount of steam condensation. Incorporation of steam-water mass exchange promotes a better prediction of behavior in reactor systems. This data for flooding with steam and water in a large diameter vertical tube can lead to a mechanistic model for flooding.Item Improvements and assessments of water auditing techniques(2009-05-15) Meyer, Sarah RuthWater auditing is an emerging method of increasing accountability for water utility systems. A water loss audit according to the methodology of the International Water Association (IWA) is applied to a major North American water utility, San Antonio Water System (SAWS), which is already a leader in conservation policies. However, some modifications to the auditing process are needed for this model?s application to a North American utility. These improvements to the IWA methodology include: calculating system input volume from multiple methods of measurements as well as numerous input points, incorporating deferred storage consumption (in this case aquifer storage and recovery) principles into the auditing process, calculating a volume of unavoidable annual real losses (allowable leakage) for a system with varied pressure zones, and defining procedures for assessing customer meter accuracy for a system. Application of the improved IWA audit method to SAWS discovered that its system input volume is being significantly undermeasured by current practices, current water loss control programs are very effective, customer accounting procedures result in large volumes of apparent loss, and current customer meter accuracy is adequate but could be marginally improved. Application of the audit process to the utility is beneficial because it facilitates increased communication between utility departments, assesses shortcomings in current policies, pin-points areas needing increased resources, and validates programs that are performing well.Item Improving capabilities for dealing with key complexities of water availability modeling(Texas A&M University, 2005-02-17) Olmos Alejo, Hector EliasWater availability has been of great concern in the State of Texas and many other places worldwide. During 1997-2003, pursuant to the 1997 Senate Bill 1, the Texas Commission on Environmental Quality (TCEQ), its partner agencies, and contractors developed a Water Availability Modeling (WAM) System based on the Water Rights Analysis Package (WRAP) model, developed at Texas A&M University. WAM has been widely applied in the State of Texas and because of its convenience, applications, and capabilities, it is planned to be implemented in other States and Countries. This thesis addresses different aspects of WAM, including conditional reliability modeling, firm yield analysis following classic and recently developed methodologies, evaluating the impact of different considerations on reliability analyses, simplification of complex WAM datasets and the display of WRAP results into ArcMap. Conditional reliability modeling evaluates short term diversion/storage reliabilities based on an initial storage level. WRAP-CON has been evaluated and improved, in addition a new modeling methodology has been developed, in which probabilities of occurrence for each hydrologic sequence is based on the relationship between storage and future flows. Recently developed WRAP capabilities have been evaluated, providing users new tools and increased flexibility. Some of these improvements are firm yield analysis, cycling and dual simulation. In addition to improved software, guidelines have also been developed, including a set to simplify extremely large WAM datasets, while maintaining the effect of all the other water rights in a basin.Item New Advances in Shale Gas Reservoir Analysis Using Water Flowback Data(2014-04-04) Alkouh, AhmadShale gas reservoirs with multistage hydraulic fractures are commonly characterized by analyzing long-term gas production data, but water flowback data is usually not included in the analysis. However, this work shows there can be benefits to including post-frac water flowback and long-term water production data in well analysis. In addition, field data indicate that only 10-40% of the frac water is recovered after the flowback. This work addresses two main question: Where is the rest of the injected frac fluid that is not recovered and what is the mechanism that is trapping it? And how can the water flowback data be used in estimating effective fracture volume using production data analysis tools? A number of simulation cases were run for single and two phase (gas/water) for modeling flowback and long-term production periods. Various physical assumptions were investigated for the saturations and properties that exist in the fracture/matrix system after hydraulic fracturing. The results of these simulations were compared with analytical solutions and data from actual wells using diagnostic and specialized plots. The results of these comparisons led to certain conclusions and procedures describing possible reservoir conditions after hydraulic fracturing and during production. Past publications have suggested that the lost frac water is trapped in the natural fracture or imbibed into the rock matrix near the fracture face. Natural fracture spacing could be a possible explanation of the lost frac water. These concepts are tested and the challenge of simulating a natural fracture with trapped water without imbibition is solved using a new hybrid relative permeability jail. This concept was tested for the period of flowback, shut-in and production. This work presents the benefits of a new method for combining water flowback and long-term water production data in shale gas analysis. Water production analysis can provide effective fracture volume which was confirmed by the cumulative produced water. This will help when evaluating fracture-stimulation jobs. It also shows the benefits of combining flowback and long-term water production data in the analysis of shale gas wells. In some cases, the time shift on diagnostic plots changes the apparent flow regime identification of early gas production data. This leads to different models of the fracture/matrix system. The presented work shows the importance of collecting and including water flowback data in long-term production data.Item Nonlinear Phenomena Induced by Millijoule Femtosecond Laser Pulses at an Air-water Interface(2013-11-04) Strycker, BenjaminFemtosecond laser pulses with millijoule energy have the potential to be used in many applications for remote sensing in marine environments. In this dissertation, we investigate some of the basic phenomena involved when a loosely focused, potentially filament-forming millijoule femtosecond laser pulse propagating in air interacts with an air-water interface. As an introduction to the primary investigation, we discuss concepts and experiments relevant to the primary investigation: the interaction of millijoule femtosecond laser pulses with an air-water interface. We first discuss linear femtosecond pulse propagation in water and describe an experiment investigating pulse attenuation behavior in water in the linear pulse propagation regime. We find no deviations from exponential attenuation, in contradiction to some earlier works. We then discuss nonlinear pulse propagation in water and describe an experiment investigating the onset of nonlinear pulse propagation and spectral transformation in water. We find that nonlinear femtosecond pulse propagation begins at a peak pulse intensity of about 1010 W/cm2. This experiment provides a convenient segway into the discussion and investigation of femtosecond laser filaments. We describe an experiment in which two filaments interact within liquid methanol and exchange energy. We then discuss laser- induced breakdown spectroscopy and demonstrate that different LIBS signal intensity thresholds can be utilized to image shallowly buried objects. Finally, all of these concepts are brought together to discuss the interaction of millijoule femtosecond laser pulses with an air-water interface. We catalogue and describe the main phenomena involved, which span about 12 orders of magnitude in time. We then describe the characteristics of the acoustic shockwaves generated by this interaction and demonstrate the usefulness of millijoule femtosecond laser pulses in several remote sensing applications in marine environments.Item Novel instrumentation for a scattering independent measurement of the absorption coefficient of natural waters, and a new diffuse reflector for spectroscopic instrumentation and close cavity coupling(Texas A&M University, 2007-04-25) Musser, Joseph AlanWe report results for the development of a flow-through integrated cavity absorption meter (ICAM.) Absorption measurements have been made with 2% or less change in the signal in the presence of up to 10 m-1 of scattering in the medium. The operating range of the ICAM ranges from 0.004 m-1 to over 40 m-1 of absorption. This range allows one to use a single instrument to measure the absorption from sediment laden rivers out to the cleanest of ocean waters. Further, the ICAM signal has been shown to be independent of the flow rate and turbulence in the medium. In addition we report the development of a diffuse reflector which, to our best knowledge, has the highest measured diffuse reflectivity of 0.998 at 532 nm and 0.996 at 266 nm. We also show that the average distance a photon travels between successive reflections in an integrating cavity of arbitrary shape is four times the volume divided by the surface area, 4 V/S. Further, for a cavity which is formed by planes tangent to an inscribed sphere and which maintains a homogeneous and isotropic field, the average distance traveled by a photon between successive reflections is equal to 4 V/S of the inscribed sphere. Thus, each cavity has the same ratio of V/S as the inscribed sphere. These advances lead to an increase in the sensitivity of absorption spectroscopy. The sensitivity approaches that of cavity ring down spectroscopy (CARS), without the adverse scattering effects traditionally associated with CARS.Item Photochemistry of aromatic hydrocarbons: implications for ozone and secondary organic aerosol formation(Texas A&M University, 2006-08-16) Suh, InseonAromatic hydrocarbons constitute an important fraction (~20%) of total volatile organic compounds (VOCs) in the urban atmosphere. A better understanding of the aromatic oxidation and its association in urban and regional ozone and organic aerosol formation is essential to assess the urban air pollution. This dissertation consists of two parts: (1) theoretical investigation of the toluene oxidation initiated by OH radical using quantum chemical and kinetic calculations to understand the mechanism of O3 and SOA precursors and (2) experimental investigation of atmospheric new particle formation from aromatic acids. Density functional theory (DFT) and ab initio multiconfigurational calculations have been performed to investigate the OH-toluene reaction. The branching ratios of OH addition to ortho, para, meta, and ipso positions are predicted to be 0.52, 0.34, 0.11, and 0.03, respectively, significantly different from a recent theoretical study of the same reaction system. Aromatic peroxy radicals arising from initial OH and subsequent O2 additions to the toluene ring are shown to cyclize to form bicyclic radicals rather than undergoing reaction with NO under atmospheric conditions.Isomerization of bicyclic radicals to more stable epoxide radicals possesses significantly higher barriers and hence has slower rates than O2 addition to form bicyclic peroxy radicals. At each OH attachment site, only one isomeric pathway via the bicyclic peroxy radical is accessible to lead to ring cleavage. Decomposition of the bicyclic alkoxy radicals leads primarily to formation of glyoxal and methyl glyoxal along with other dicarbonyl compounds. Atmospheric aerosols often contain a considerable fraction of organic matter, but the role of organic compounds in new nanometer-sized particle formation is highly uncertain. Laboratory experiments show that nucleation of sulfuric acid is considerably enhanced in the presence of aromatic acids. Theoretical calculations identify the formation of an unusually stable aromatic acid-sulfuric acid complex, which likely leads to a reduced nucleation barrier. The results imply that the interaction between organic and sulfuric acids promotes efficient formation of organic and sulfate aerosols in the polluted atmosphere because of emissions from burning of fossil fuels, which strongly impact human health and global climate.Item Region-specific role of water in collagen unwinding and assembly(Texas A&M University, 2008-10-10) Mayuram Ravikumar, KrishnakumarConformational stability of the collagen triple helix affects its turnover and determines tissue homeostasis. Although it is known that the presence of imino acids (prolines or hydroxyprolines) confer stability to the molecule, little is known regarding the stability of the imino-poor region lacking imino acids, which plays a key role in collagen cleavage. In particular, there have been continuing debates about the role of water in collagen stability. We addressed these issues using molecular dynamics simulations on 30-residue long collagen triple helices, including a structure that has a biologically relevant 9-residue imino-poor region from type III collagen (Protein Data Bank ID: 1BKV). We characterized the conformational motion of the molecule that differs between imino-rich and imino-poor regions using a torsional map approach. At temperatures of 300 K and above, unwinding initiates at a common cleavage site, the glycine-isoleucine bond in the imino-poor region. This provides a linkage between previous observations that unwinding of the imino-poor region is a requirement for collagenase cleavage, and that isolated collagen molecules are unstable at body temperature. Unwinding of the imino-poor region is controlled by dynamic water bridges between backbone atoms with average lifetimes on the order of a few picoseconds, as the degree of unwinding strongly correlated with the loss of water bridges, and unwinding could be either prevented or enhanced, respectively by enforcing or forbidding water bridge formation. While individual water bridges were short-lived in the imino-poor region, the hydration shell surrounding the entire molecule was stable even at 330 K. The diameter of the hydrated collagen including the first hydration shell was about 14 ?, in good agreement with the experimentally measured inter-collagen distances. These results elucidate the general role of water in collagen turnover: water not only affects collagen cleavage by controlling its torsional motion, but it also forms a larger-scale lubrication layer mediating collagen self-assembly.Item Select Economic Implications for the Biological Control of Arundo donax along the Rio Grande(2010-10-12) Seawright, Emily KayeArundo donax, or giant reed, is a large, bamboo-like plant native to Spain that has invaded several thousand acres of the Rio Grande riparian in Texas. The plant grows to 18-24 feet, consuming large quantities of water per acre per year. With concern of increased water demands in the Texas Lower Rio Grande Valley region, the United States Department of Agriculture-Agricultural Research Service (USDA)ARS) is investigating four herbivorous insects as potential biological control agents for Arundo donax to facilitate increased water supply. This study examines select economic implications for agricultural water users in the United States of applying these biological control agents along the Rio Grande. The research includes (a) estimating the value of the water saved due to the reduction of Arundo donax, (b) a benefit-cost analysis, (c) regional economic impact analysis, and (d) an estimate of the per-unit cost of water saved over a 50-year planning horizon (2009 through 2058). The model ArundoEcon is used to perform a deterministic analyses using low- and high-marginal-composite acre values. Regional results indicate present values of farmlevel benefits ranging from $97.80 to $159.87 million. Benefit-cost ratios are calculated with normalized prices and range from 4.38 to 8.81. Sensitivity analyses provide a robust set of results for Arundo water use, replacement species water use, Arundo expansion rate after control, value of water, and the cost of the program. The pre-production processes and farm-gate economic impact analysis is estimated using multipliers from the IMPLAN model. Regional results reveal a range of $8.90 to $17.94 million annually in economic output and 197 to 351 new jobs for the year 2025. Further results show the cost per acre-foot of water saved is $44.08. This amount is comparable to other projects designed to conserve water in the region. The USDA)ARS, Weslaco, Texas Arundo donax biological control project realizes positive results for the benefit-cost ratios, economic impact analyses, and competitive results for the per-unit cost of saving water. These positive results indicate this project will have positive economic implications for the U.S. and the Texas Lower Rio Grande Valley.Item Specific Ion Effects on Interfacial Phenomena(2012-02-14) Flores Araujo, SarahA new interdisciplinary facet of chemistry has developed, as we attempt to comprehend complex interfacial phenomena in which ions play crucial roles. Understanding the mechanisms by which ions affect water at surfaces and interact with the molecules dissolved in it, pose a ubiquitous challenge with enormous implications for biological and physical sciences. These represent steps towards unraveling mechanisms in protein folding and crystallization, protein-protein interactions, enzymatic activity, implant biocompatibility, atmospheric chemistry phenomena, and even in more inorganic processes like metal oxide dissolution and corrosion; all of them fundamental technological challenges. In this thesis, the specific ion effects on interfacial water structure adjacent to air/water and solid/water interfaces were explored using vibrational sum frequency spectroscopy. At the air/water interface, monolayers of bovine serum albumin, elastin-like peptides, and surfactants, were analyzed in presence of subphases that consisted of different sodium salts and varying pH value. The results suggested that anions interact directly with the protein?s surface, and their effects on water structure are dominated by the charge state of the interfacial layer, rather than the detailed chemical structure of the macromolecules. At the solid/liquid interface, water structure at surfaces like quartz, octadecyltrichlorosilane-covered quartz, and titanium oxide, confirmed that the propensities of anions to adsorb at an interface are favored for more polarizable anions, following the Hofmeister order, and disproving the notion that the order of the interaction can be inverted with changes in charge sign or degree of hydrophobicity of the surface. Similarly, by analyzing interfacial water structure we performed one of the very first systematic studies on the interactions of cations with metal oxide surfaces. The results showed that specific cation effects were quite prominent at low concentration and high pH value, following a direct Hofmeister series, which can be explained in terms of charge density, polarizability, and basicity of the oxide surfaces. Our findings are of interest, since they provide with essential information not only to understand protein phenomena associated with neurodegenerative conditions like Alzheimer, but also by proving the generality of ion interactions beyond biological, we can even influence the development of the next generations of microprocessors and beyond.Item Strategies to reduce terminal water consumption of hydraulic fracture stimulation in the Barnett Shale(2009-08) Harold, Jennifer Marie Secor; Groat, Charles G.; Schuster, Stefan K.; Fialkoff, Jason S.Horizontal drilling and hydraulic fracture stimulation have enabled the economic development of unconventional resource plays. An average horizontal well in the Barnett Shale requires 3 to 4 million gallons of fresh water, 90% of which is used for hydraulic fracture stimulation. While the water consumption of Barnett Shale operations is less than 1% of total Region C consumption, extended drought conditions and competing demands for water resources are placing pressure on operators to reduce terminal water consumption. Strategies which reduce water requirements associated hydraulic fracture stimulation without compromising the efficiency and cost of energy production are essential in developing a comprehensive policy on energy-water management. Recycling and reuse technologies were evaluated on the basis of performance, cost, and capacity to treat reclaimed flowback water and oilfield brine. Recycling flowback fluids for future hydraulic fracture applications is the most practical repurposing of oilfield waste. The low TDS content of flowback derived from water-based fracs permits multiple treatment options. Mobile thermal distillation technology has emerged as the prevailing technique for recycling flowback water, yielding maximum water savings and reduced operating costs. The estimated cost of recycling flowback water by thermal distillation is $3.35/bbl. Compared to the current cost of disposal, recycling provides an opportunity to minimize waste and reduce the fresh water requirements of hydraulic fracture stimulation at an incremental cost. The stewardship role of the Texas Legislature is to protect the water resources of the state and to facilitate the Regional Water Planning Process, ensuring future water needs are met. The support and participation of the Legislature and other planning entities is critical in advancing the energy-water nexus. As operators pursue innovative water management practices to reduce terminal water consumption in the oilfield, the Barnett Shale positions itself as a model for sustainable water use in the development of unconventional shale resources. The cost of recycling and reuse technology limits the participation of small and mid-size operators who possess the greatest market share of the Barnett Shale. Funding for research and implementation of water-conscious strategies such as shared recycling facilities, CO2 capture and storage, and pipeline infrastructure would create multi-user opportunities to promote conservation and reduce net consumption of fresh water supplies. Through the integration of technology and policy, terminal water consumption in the Barnett Shale can be greatly diminished.Item Synthesis, Characterization and Anion Complexation of Cationic Main Group Lewis Acids(2011-10-21) Kim, YoungminDue to favorable Coulombic effects, cationic main group Lewis acids should be more Lewis acidic than their neutral counterparts. To investigate this idea, this dissertation has been dedicated to the synthesis, characterization and anion binding properties of new cationic Lewis acids for selective anion complexation. The cationic borane [p-(Mes2B)C6H4(PPh3)] displays an enhanced anion affinity towards fluoride due to a combination of Coulombic and hydrophobic effects, and can be used to detect fluoride at levels below 4 ppm in water. A related phosphonium borane featuring a chromophoric dansyl amide moiety has been synthesized and used for the fluorescence turn on sensing of CN?. This borane is very sensitive and can be used to measure cyanide concentration in the 20-30 ppb range in water. The bidentate borane [o-(Mes2B)C6H4(PPh2Me)] is selective for N3 ? over F? in water/chloroform biphasic mixtures because of the lipophilic character of the azide anion, as well as its ability to interact with both the boron and phosphorus Lewis acidic sites of the receptor via chelation (lp(N)s*(P-C)). Sulfonium borane [o(Mes2B)C6H4(SMe2)] can detect up to 50 ppb of cyanide in water at pH 7 due to favorable Coulombic effects. The sulfonium moiety interacts with the cyanide anion through both bonding and back-bonding interactions, thus enhancing the unusual affinity of [o-(Mes2B)C6H4(SMe2)] towards cyanide. This approach can be extended to Lewis acids containing fluorosilanes such as [1-Ant2FSi-2-Me2S-(C6H4)] whose fluoride affinity exceeds that of neutral fluorosilanes by several orders of magnitude.Item The TAMU Water Project: Critical Environmental Justice as Pedagogy(2010-10-12) Munoz, Marissa IselaThe TAMU Water Project is a trans-disciplinary collaborative that works to address the water needs of rural communities along the Texas/Mexico border called colonias. Modeled initially after the work of Potters for Peace, the TAMU Water Project recognizes access to potable water as a human right and is dedicated to the production, distribution, and research of affordable, appropriate technology to purify water. This thesis proposes critical environmental justice as the theoretical framework and lens through which to examine the TAMU Water Project as a praxis of public pedagogy. Extant data in the form of articles, publications, presentations, photo essays, and video, were analyzed using an inductive process of content analysis and thick description to prove that the TAMU Water Project fulfills the criteria of critical environmental justice and can be used as an example of critical environmental justice as pedagogy.Item Thermal signature reduction through liquid nitrogen and water injection(Texas A&M University, 2005-02-17) Guarnieri, Jason AntonioThe protection of aircraft against shoulder fired heat seeking missiles is of growing concern in the aviation community. This thesis presents a simple method for shielding the infrared signature of a jet engine from heat seeking missiles. The research efforts investigated two approaches to shield the thermal signature of the Noel Penny Type 401 turbojet at the Texas A&M University Propulsion Lab Test Cell. First, liquid nitrogen was injected through a manifold at a flow rate equivalent to the flow rate of exhaust gases, producing a small temperature reduction in the exhaust but no infrared shielding. Second, water was injected at a flow rate of 13% of the flow of exhaust gases, producing a greater temperature reduction and some shielding. Water was then injected through a manifold at a ?ow rate of 118% of the flow rate of exhaust gases, producing a substantial reduction in temperature and complete shielding of the infrared signature. Additionally, numerical simulations were performed using FLUENT to support these experiments. Results are presented in the form of thermocouple data and thermal images from the experiments, and in the form of temperature contours and streamtraces from the simulations.