Physical Sciences and Mathematics Commons^™

Environmental Assessment Of Used Motor Oil In The Ciudad Juarez-El Paso Area, Alma Leticia Figueroa

Open Access Theses & Dissertations

As a hazardous waste generated in large amounts worldwide, used motor oil (UMO) is an important issue for environmental science. UMO contains the carcinogenic and mutagenic compounds Polycyclic Aromatic Hydrocarbons (PAHs). Unless properly managed and disposed of PAHs remain in the environment, principally in sediments and soil. From such environmental sinks, PAHs can migrate to watersheds contaminate drinking water, and damage ecosystems and human health.

Generators of used oil include "businesses that handle used oil through commercial or industrial operations or from the maintenance of vehicles and equipment," (United States Environmental Protection Agency (USEPA), 2013). An example of such a …

Uptake Of Copper And Cerium By Alfalfa, Lettuce And Cucumber Exposed To Nceo2 And Ncuo Through The Foliage Or The Roots: Impacts On Food Quality, Physiological And Agronomical Parameters, Jie Hong

Open Access Theses & Dissertations

Nanotechnology is increasingly attracting attention not only for its variety of applications in modern life, but for the potential negative effects that nanomaterials (NMs) can cause in the environment and human health. Studies have shown varied effects of engineered nanoparticles (ENPs) on plants; however, most of these studies focused on the interaction of NPs with plants at root level. The increasing production and use of NPs have also increased the atmospheric amounts of NPs, which could be taken up by plants through their leaves. Cucumbers (Cucumis sativus L.) are broad leaf plants commonly grown both commercially and in home vegetable …

Furthering Our Understanding And Assessing The Effectiveness Of Scaling Patterns And Controls Of Land-Atmosphere Carbon Exchange In A Shrubland Of The Chihuahuan Desert With Novel Cyberinfrastructure, Aline Jaimes

Open Access Theses & Dissertations

Over the last century, arid and semiarid regions have undergone intense desertification and in many regions, vegetation has shifted from grassland to shrubland dominated ecosystems. This land cover change has important implications for how desert ecosystems function - especially with regards to land-atmosphere exchange of carbon, water, and energy. Although the extent of desertified landscapes is expected to expand over the next 30 to 40 years, there is a relatively poor understanding of how this state transition will impact ecosystem function and feedbacks to other components of the earth system. Key to addressing this challenge is an improved understanding of …

Experimental Investigation Of Syngas Flame Stability Using A Multi-Tube Fuel Injector In A High Pressure Combustor, Sergio Elzar Maldonado

Open Access Theses & Dissertations

Over 92% of the coal consumed by power plants is used to generate electricity in the United States (U.S.). The U.S. has the world's largest recoverable reserves of coal, it is estimated that reserves of coal will last more than 200 years based in current production and demand levels. Integrated Gasification Combined Cycle (IGCC) power plants aim to reduce the amount of pollutants by gasifying coal and producing synThesis gas. SynThesis gas, also known as syngas, is a product of coal gasification and can be used in gas turbines for energy production. Syngas is primarily a mixture of hydrogen and …

Design And Evaluation Of A High Temperature/Pressure Supercritical Carbon Dioxide Direct Tubular Receiver For Concentrating Solar Power Applications, Jesus Daniel Ortega

Open Access Theses & Dissertations

This work focuses on the development of a solar power thermal receiver for a supercritical-carbon dioxide (sCO2), Brayton power-cycle to produce ~1 MWe. Closed-loop sCO2 Brayton cycles are being evaluated in combination with concentrating solar power to provide higher thermal-to-electric conversion efficiencies relative to conventional steam Rankine cycles. High temperatures (923 - 973 K) and pressures (20 - 25 MPa) are required in the solar receiver to achieve thermal efficiencies of ~50%, making concentrating solar power (CSP) technologies a competitive alternative to current power generation methods. In this study, the CSP receiver is required to achieve an outlet temperature of …

Residential Electricity Demand In Arkansas, Ileana M. Resendez

Open Access Theses & Dissertations

This study analyzes residential electricity demand in Arkansas. Explanatory variables utilized include real per capita income, residential electricity price, heating degree days, cooling degree days, and residential natural gas price. The results indicate that the income effect dominates the substitution effect given a real personal income increase and a decline in real electricity rates in the state of Arkansas during the period under study.

Water Recovery From Silica Saturated Ro Concentrate By The Concentrate Enhanced Reverse Osmosis Process, Gautam Patwardhan

Open Access Theses & Dissertations

Membrane fouling due to silica precipitation during reverse osmosis (RO) continues to be documented as the most common challenge in attaining stable continuous operation of RO systems across water treatment plants (1). Silica scale precipitation is time dependent and involves multiple steps leading to aqueous polymerization, condensation of polymers to form colloids, and deposition onto a solid surface (2). Exceeding the solubility of silica, widely considered to be in the range of 100-140 ppm, under a pH of 8 at 25 °C by various researchers, results in the precipitation of silica on the membranes, thereby limiting water recovery. Once the …

Natural Selectivity Of Nickel And Vanadium In Crude Oil, Olienka P. De La O Fernandez

Open Access Theses & Dissertations

Nickel and Vanadium have always been found in crude oil all around the world. The metal content is found mainly in porphyrin structures in the asphaltene fraction of the petroleum. In order to determine the reason for this natural preference, a set of experiments testing thermodynamics, kinetics, and other factors were performed. Candidate metalloporphyrins containing Vanadyl, Chromium, Iron, Nickel, Copper and Zinc were analyzed through chemical reactions characterized using Silica Column Chromatography, HPLC, MS and UV-Visible. Theoretical analysis of the stability of metalloporphyrins was conducted using DFT/NRLMOL for computational calculation. The analysis of all factors leads us to conclude that …

Determination Of The Uptake And Effects Of Tio2 Nanoparticles In Cucumber (Cucumis Sativus), Alia D. Servin

Open Access Theses & Dissertations

The profuse use of nanoparticles (NPs) in consumer products has raised concerns about their impacts in environmental and human health and possible transfer into the food chain through plants. Cucumber (Cucumis sativus L.) is a widely cultivated garden vegetable that could be in contact with NPs through biosolids. In this Dissertation research, the impact of TiO2 NPs was evaluated in cucumber plants grown in hydroponics and sandy loam soil. Hydroponically grown plants were treated for 15 days with 0-4000 mg/L of TiO2 NPs, and their vegetative tissues were studied using synchrotron micro X-Ray Fluorescence (micro-XRF) and Micro X-ray Absorption Near …

Risk Assessment Of Waterborne Cryptosporidium, Victoria Norma Ochoa

Open Access Theses & Dissertations

In an effort to update the risk assessment of waterborne Cryptosporidium an additional and more complete human dose-response dataset of the parasite was used to calculate the risk of infection. The complete data studied contains larger human outcomes than the initial prior risk assessment evaluated by Haas et. al. in 1999. Quantitative analysis of the complete dose-response indicates that it no longer follows the Exponential Model used to estimate the risk for the initial data. The complete dataset appears to provide a better fit with the Beta-Poisson Model and even a dose independent constant risk model, which shows a considerable …

Effects Of Cerium Oxide Nanoparticles In Cereals: Insights Into The Toxicity Mechanisms And Macromolecular Modifications, Cyren Mendoza Rico

Open Access Theses & Dissertations

Despite the inundation of studies on the interaction of engineered nanomaterials (ENMs) with plants, investigations involving complete life cycle (i.e from seedling establishment to full maturity) are still lacking. Assessments on the nutritional value of plants cultivated to full maturity in ENMs-treated soil are also missing. Cerium oxide nanoparticles (nCeO2) have significant interactions with plants; however, there are no life cycle studies yet on their implications in cereals like rice (Oryza sativa L.), wheat (Triticum aestivum L.), and barley (Hordeum vulgare L.). These cereals are globally important crops that support the economic activity, and nutritional and health needs of billions …

Solar Pv Power Generation Forecasting Using Hybrid Intelligent Algorithms And Uncertainty Quantification Based On Bootstrap Confidence Intervals, Donna Alhakeem

Open Access Theses & Dissertations

This Thesis focuses on short-term photovoltaic forecasting (STPVF) for the power generation of a solar PV system using probabilistic forecasts and deterministic forecasts. Uncertainty estimation, in the form of a probabilistic forecast, is emphasized in this Thesis to quantify the uncertainties of the deterministic forecasts. Two hybrid intelligent models are proposed in two separate chapters to perform the STPVF. In Chapter 4, the framework of the deterministic proposed hybrid intelligent model is presented, which is a combination of wavelet transform (WT) that is a data filtering technique and a soft computing model (SCM) that is generalized regression neural network (GRNN). …

Biofuel Feedstock Optimization Considering Different Land Cover Scenarios And Watershed Impacts, Rodney Wayne Vance

Open Access Theses & Dissertations

With an increased demand for renewable energy production, especially the conversion of biomass to biofuels, perennial grasses are gaining interest as a renewable source of biofuel feedstocks. Identifying the trade-offs between bioenergy crop cultivation and nutrient runoff, erosion, and water requirements will be important as the demand for these crops continues to grow. The primary objective of this study is develop an integrated optimal control model that estimates the potential effects on water quality and demand and soil erosion from cultivating switchgrass and other perennial grasses instead of conventional crops at the watershed scale. The Soil and Water Assessment Tool …

Depositional And Sequence Stratigraphic Framework Of An Exposed Neoproterozoic Suprasalt Minibasin At Patawarta Diapir, Flinders Ranges, South Australia, Cora Evelyn Gannaway

Open Access Theses & Dissertations

Outcrops of mixed carbonate/siliciclastic strata comprise the Neoproterozoic (Marinoan) Wilpena Group at Patawarta diapir in the Flinders Ranges, South Australia. Patawarta diapir is a ramping allochthonous salt sheet flanked by suprasalt and subsalt minibasin strata. The stratal and structural attributes of the coeval minibasin fills afford a unique perspective on lateral and vertical salt migration and the impacts of salt-modified bathymetry in shallow marine depositional environments. This study documents the depositional and diagenetic facies, stratal thickness trends, and structural style and stratal geometries of the suprasalt minibasin fill and correlates it to the previously studied subsalt minibasin fill. The goal …

Sedimentologic, Stratigraphic, And Diagenetic Analysis Of Microbialite-Bearing Lacustrine Rift Sequence Within The Lower Cretaceous Yucca Formation, Indio Mountains, West Texas, Xiaowei Li

Open Access Theses & Dissertations

This study sedimentologically, stratigraphically, and diagenetically analyzed strata of the upper member of the Lower Cretaceous Yucca Formation in the Indio Mountains, West Texas in order to develop an outcrop-based analog model for similar facies that form major hydrocarbon reservoirs in the Pre-salt rift basins of the South Atlantic margin. The lower Cretaceous strata of the Indio Mountains were deposited in rift basins that formed along the eastern margin of the Chihuahua Trough under similar greenhouse climate conditions as the South Atlantic basins.

Eleven lithofacies are recognized from the upper member of the Yucca Formation to the base of the …

A Long- And Short-Run Analysis Of Electricity Demand In Ciudad Juarez, Ericka Cecilia Mendez

Open Access Theses & Dissertations

Economic growth and appliance saturation are increasing electricity consumption in Mexico. Annual frequency data from 1990 to 2012 are utilized to develop an error correction framework that sheds light on short- and long-run electricity consumption behavior in Ciudad Juarez, a large Mexican metropolitan economy at the border with the United States. The results for this study reveal that electricity is an inelastic normal good in this market. Moreover, natural gas is found to be a weak complement to electricity. With regards to the customer base in this urban economy, population, employment, and income exercise positive and statistically significant impacts on …

Growth And Analysis Of Micro And Nano Cdte Arrays For Solar Cell Applications, Brandon Adrian Aguirre

Open Access Theses & Dissertations

CdTe is an excellent material for infrared detectors and photovoltaic applications. The efficiency of CdTe/CdS solar cells has increased very rapidly in the last 3 years to ~20% but is still below the maximum theoretical value of 30%. Although the short-circuit current density is close to its maximum of 30 mA/cm2, the open circuit voltage has potential to be increased further to over 1 Volt. The main limitation that prevents further increase in the open-circuit voltage and therefore efficiency is the high defect density in the CdTe absorber layer. Reducing the defect density will increase the open-circuit voltage above 1 …

Simulation Of Heat And Mass Transfer In Suns River Solar Distillation, Houman Azari

Open Access Theses & Dissertations

Many regions around the world have limited fresh water resources, and we need to desalinate brackish water resources for drinking and irrigation purposes. Most of the world is also facing energy challenges which encourages engineers and scientists to use renewable energy resources instead of hydrocarbon fuels. Arid regions such as the Middle East, many African countries, and the southwestern United States typically have abundant solar irradiance and brackish or saline water supplies. Solar-thermal desalination could be an important supply of fresh water in these regions.

The classic solar still is not efficient for providing large amounts of clean water for …

Numerical Investigation Of Impact Of Relative Humidity On Droplet Accumulation And Film Cooling, Luz Irene Bugarin

Open Access Theses & Dissertations

During the summer, high inlet temperatures affect the power output of gas turbine systems. Evaporative coolers have gained popularity as an inlet cooling method for these systems. Wet compression has been one of the common evaporative cooling methods implemented to increase power output of gas turbine systems due to its simple installation and low cost. This process involves injection of water droplets into the continuous phase of compressor to reduce the temperature of the flow entering the compressor and in turn increase the power output of the whole gas turbine system. This study focused on a single stage rotor-stator compressor …

Spingolipid Metabolism In A Reptillian Protozoan, Entamoeba Invadens, Duran Dogan Debons

Open Access Theses & Dissertations

Entamoeba invadens (hereinafter E. invadens) is an anaerobic parasitic protozoan that can be found in water and soil. Although the host organisms for this parasite are snakes, lizards, and other reptile species, the parasite is morphologically identical to Entamoeba histolytica, a causative agent of human amebiasis. Entamoeba inavdens exists in two morphological forms--(1) a replicative trophozoite, and (2) a relatively dormant cyst. While the transformation of cyst to trophozoites (called "excystation") takes place in the stomach, the differentiation of trophozoites to cyst (known as "encystation"), occurs in the small intestine. Unlike the cyst, a trophozoite is unable to survive …

Impact Of Zinc Oxide Nanoparticles On Green Pea Plant & Seed Quality And Effects On Physiological Traits Of Green Peas, Corn, And Zucchini By Silver Nanoparticles, Arnab Mukherjee

Open Access Theses & Dissertations

The production and use of numerous engineered nanomaterials (ENMs) have increased exponentially over the past decade. Nanoparticles (NPs), ENMs possessing diameter between 1-100 nm, (NPs), are widely used in many applications. Worldwide consumption of NPs has increased their possible release into the environment. This, in turn, has elevated the extent of the potential impacts of NP exposure to living and non-living organisms. This is why the assessment of the impact of NPs on different environmental components, especially on plants, the producer in the food web, has become a very important aspect of nano-ecotoxicology. However, studies focusing on phytotoxicity and effects …

Hispanic Communities And Environmental Justice: A Comparative Study Of Mobility And Exposure To Air Toxics In Houston, Maricarmen Hernandez

Open Access Theses & Dissertations

Environmental justice research has focused too little attention on immigrant communities. This study extends from the premise that themes of immigration and mobility among racial/ethnic minority communities must be more carefully analyzed by environmental justice (EJ) scholars. By clarifying why Hispanic people live where they live, and what factors shape their exposures to cancer risks from hazardous air pollutants, this study aims to contribute to the existing EJ body of knowledge. The analysis employs qualitative methods, implemented as part of a larger National Science Foundation-funded study. In-depth semi-structured phone interviews were conducted with randomly selected Hispanic individuals, some of whom …

Alkali Promoted Molybdenum (Iv) Sulfide Based Catalysts, Development And Characterization For Alcohol Synthesis From Carbon Monoxide And Hydrogen, Belinda Delilah Molina

Open Access Theses & Dissertations

For more than a century transition metal sulfides (TMS) have been the anchor of hydro-processing fuels and upgrading bitumen and coal in refineries worldwide. As oil supplies dwindle and environmental laws become more stringent, there is a greater need for cleaner alternative fuels and/or synthetic fuels. The depletion of oil reserves and a rapidly increasing energy demand worldwide, together with the interest to reduce dependence on foreign oil makes alcohol production for fuels and chemicals via the Fischer Tropsch synthesis (FTS) very attractive. The original Fischer-Tropsch (FT) reaction is the heart of all gas-to-liquid technologies; it creates higher alcohols and …

Evaluation Of Ozone Trends In Southern Doña Ana County, New Mexico Thru Wind Rose Analysis And Use Of Noaa Hysplit Model, Maria Aurelia Sisneros

Open Access Theses & Dissertations

The objective of this study was to determine whether increasing ozone concentrations in 2012 and 2013 at the Santa Teresa air quality monitor in Doña Ana County, New Mexico were due to a local point source impacting this monitor only or part of a regional phenomenon that affects all the monitors within the Paso del Norte Region. In addition, the study focused on identifying local and regional/long-range source areas contributing transport ozone to the study area (southern Doña Ana County).

The study showed that increasing ozone levels were not unique to the Santa Teresa monitor due to the fact that …