Dissertations / Theses on the topic 'Reef Degradation'

Coral reefs are among the most diverse and productive ecosystems on earth, and are critical to the survival of tropical marine ecosystems and sustenance of local human populations. However, coral reefs are quite vulnerable to disturbances, both natural and anthropogenic. This thesis looks at how coral reef communities have responded to climactic disturbances, particularly the 1997-98 El Niño Southern Oscillation (ENSO) and subsequent coral bleaching and mortality that affected much of the Indian Ocean, including the coastal waters of Tanzania, where the study was conducted. In particular, it investigates the effects of coral bleaching, habitat degradation and reef spatial arrangement on reef fish assemblages. Habitat structural complexity and spatial arrangement of reefs had an effect on reef fish communities. Fish communities showed patterns in distribution among habitats and between patch and continuous reefs. Fishes preferred live to bleached/dead or eroded coral, but trophic groups reacted differently to patch and continuous reefs. There were slight changes in fish abundance and significant changes in fish diversity on experimental, bleached branching Acropora coral plots over a period of one year. While fish abundance on one site increased shortly after a bleaching event, 6 years later fish abundance had decreased significantly. Conversely, coral reef communities in northern Tanzania had changed little over an 8-year period, with minor changes associated with the 1997-98 ENSO and the presence or absence of fisheries management. The coral reefs in the region were found to show high variability in community structure and responses of associated fish and invertebrate communities. The findings of this thesis indicate the importance of habitat structure and spatial arrangement of reefs, the detrimental effects of coral bleaching, and the possibility that some reefs and some (generalist) reef fish taxa may exhibit resilience to climate change.
At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Thesis (Ph. D.)--University of California, San Diego, 2009.
Title from first page of PDF file (viewed July 7, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references.

Many studies measuring the occurrence of pharmaceuticals, understanding their environmental fate and the risk they pose to surface water resources have been published. However, very little is known about the relevant transformation products which result from the wide range of biotic and abiotic degradation processes that these compounds undergo in sewers, storage tanks, during engineered treatment and in the environment. Thus, the present study primarily investigated the degradation of the steroid progesterone (P4) in natural systems (rivers), with a focus on the identification and characterisation of transformation products. Initial work focussed on assessing the removal of selected compounds (Diclofenac, Fluoxetine, Propranolol and P4) from reed beds, with identification of transformation products in a field site being attempted. However, it was determined that concentrations of parent compounds and products would be too low to work with in the field, and a laboratory study was designed which focussed on P4. Focus on P4 was based on literature evidence of its rapid biodegradability relative to the other model compounds and its usage patterns globally. River water sampling for the laboratory-based degradation study was carried out at 1 km downstream of four south east England sewage works (Blackbirds, Chesham, High Wycombe and Maple Lodge) effluent discharge points. Suspected P4 transformation products were initially identified from predictions by the EAWAG Biocatalysis Biodegradation Database (EAWAG BBD) and from a literature review. At a later stage of the present work, a replacement model for EAWAG BBD (enviPath) which became available, was used to predict P4 degradation and results were compared. Samples were analysed using low resolution and accurate-mass time-of-flight mass spectrometers. Three degradation studies were conducted. Sampling for all studies was carried out at the same time in the year to minimize temporal variability in conditions and allow for effective comparison of results. Androgenic and progesterone yeast screens were carried out to assess the biological activity of transformation products.

The objective of this study was to utilize an alternating anaerobic/aerobic sequence to biologically transform perchloroethylene to non-hazardous end products such as ethylene, CO2 and H2 using a single microbial consortia in a methanogenic and/or a homoacetogenic environment followed by a aerobic methanotrophic environment. Reductive dechlorination of PCE and TCE to cDCE and VC in an anaerobic environment is typically carried out by methanogens, sulfidogens, or homoacetogens but often (e.g. in-situ) leads to an accumulation of daughter compounds (cDCE, VC) which are more toxic than their parent compounds (PCE, TCE). Furthermore, PCE is resistant to degradation in aerobic environments while VC and cDCE are readily oxidized co-metabolically by aerobic methanotrophic bacteria, among others. In order to achieve complete mineralization of chlorinated solvents using a biotic system, an anaerobic/aerobic treatment strategy was investigated. This strategy has been accomplished successfully at a lab scale with anaerobic and aerobic reactors in series, and in-situ anaerobic zones with downgradient aerobic zones have been proposed in the field. In contrast, the focus of this research was to expose single mixed microbial consortia to sequential anaerobic/aerobic treatments in order to determine if reductive dechlorination could be sustained following aerobic phases of treatment. If possible this would imply that the anaerobic and aerobic zones (in-situ) or reactors (ex-situ) would not necessarily have to be spatially separated. In pure or dilute cultures where soil material is not present strict anaerobes would typically not resume metabolic activity if exposed to frequent aerobic phases of treatment. However in aquifer material or reactors with large floc/granules it might be possible due to the protection of anaerobic micro-environments as a result of diffusion limitations. Microcosms contained in sealed 120-mL serum bottles were used to generate experimental data including autoclaved abiotic controls with mercuric chloride. Inocula for these microcosms come from a several sources, including anaerobic digester sludge, soils, and contaminated aquifers. Once an experimental microcosm showed signs of reductive dechlorination, an aerobic treatment was implemented. The anaerobic phase of the microcosm was interrupted with a short duration aerobic phase. Headspace air or hydrogen peroxide addition was used to supply oxygen. Analytical data from the experiments indicated that anaerobic reductive dechlorination was readily accomplished during anaerobic phase experiments as PCE was sequentially dechlorinated to TCE and then to cDCE as reported in previous research reported by others in the literature. Additionally, a few mixed consortia microcosms showed evidence of further reductive dechlorination to VC and ethylene. During the sequential environment experiments, analytical data also indicated that reductive dechlorination also resumed after an aerobic sequence utilizing hydrogen peroxide as an oxidizer in the microcosm. No conclusive evidence was observed to indicate that aerobic degradation of cDCE during any of the aerobic phase treatments. This was probably due to the inocula not containing methanotrophs.
M.S.Env.E.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engineering

As fossil fuel sources continue to diminish, oil prices continue to increase, and global warming and CO2 emissions keep impacting the environment, it has been necessary to shift energy consumption and generation to a different path. Solar energy has proven to be one of the most promising sources of renewable energy because it is environmentally friendly, available anywhere in the world, and cost competitive. For photovoltaic (PV) system engineers, designing a PV system is not an easy task. Research demonstrates that different PV technologies behave differently under certain conditions; therefore energy production varies not only with capacity of the system but also with the type of module. For years, researchers have also studied how these different technologies perform for long periods of time, when exposed out in the field. In this study, data collected by the Florida Solar Energy Center for periods of over four years was analyzed using two techniques, widely accepted by researchers and industry, to evaluate the long‐term performance of five systems. The performance ratio analysis normalizes system capacity and enables the comparison of performance between multiple systems. In PVUSA Regression analysis, regression coefficients are calculated which correspond to the effect of irradiance, wind speed, and ambient temperature, and these coefficients are then used to calculate power at a predetermined set of conditions. This study allows manufacturers to address the difficulties found on system lifetime when their modules are installed out on the field. Also allows for the further development and improvement of the different PV technologies already commercially available.
M.S.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE

This thesis mainly focuses on two important aspects of the photovoltaic modules. The first aspect addressed the high voltage bias testing and data and degradation analysis of high voltage biased thin film photovoltaic modules. The second aspect addressed the issues of reliability and durability of crystalline silicon module. Grid-connected photovoltaic systems must withstand high voltage bias in addition to harsh environmental conditions such as intermittent solar irradiance, high humidity, heat and wind. a-Si:H thin-film photovoltaic modules with earlier generation SnO2:F transparent conducting oxide (TCO) on the front glass installed on the FSEC High Voltage Test Bed were monitored since December 2001. The data was collected on a daily basis and analyzed. The leakage currents for some chosen time period were calculated and compared with the measured values. Current-voltage characteristic measurements were carried out to check any reduction in the power. Samples were cored and extracted for analysis from one of the -600 V biased modules. Leakage currents in high-voltage-biased laminates specially prepared with improved SnO2:F TCO are being monitored in the hot and humid climate in Florida. Negatively-biased modules showed clear signs of delamination. The leakage currents in high-voltage biased photovoltaic modules are functions of both temperature and relative humidity. Photovoltaic module leakage conductance was found to be thermally stimulated with a characteristic activation energy that depends on relative humidity. The adhesional strength was lost completely in the damaged area. Leakage current values from support to ground in new, unframed laminates fabricated with improved SnO2:F TCO layer were ~100 times lower under the high voltage bias in hot and humid environment. Information on the failure of field deployed modules must be complemented with why and how the modules fail while considering the issues of reliability and durability of crystalline silicon module. At present, all the failure modes have not been identified and failure mechanisms have not been understood. Experience has shown that as the materials and processes are changed, reliability issues that apparently had been resolved resurface. A multicrystalline silicon photovoltaic module that was manufactured by a non-US company and that had shown >50% performance loss in field-deployment of <2 years in hot and dry climate were studied for degradation analysis in comparison with a mc-Si module that was manufactured by the same company and that performed well after 10 years of field-deployment in hot and humid climate.. I-V measurements were carried out to analyze the reduction in photovoltaic parameters. Solder bond strength in mc-Si photovoltaic modules were measured to understand early degradation of performance. Samples were cored and extracted for further analysis. Adhesional strength between the busline metallization and the silicon cell in a newer generation mc-Si photovoltaic module was found to be considerably lower than that in the earlier vintage module. These results can be useful for early detection and diagnosis of field reliability issues and could assist in establishing correlation between long-term field data and observations and accelerated environmental stress testing. It is suggested that more detailed study should be undertaken using unencapsulated strings of crystalline silicon modules so as to avoid complication due to encapsulant creeping beneath the ribbons.
M.S.M.S.E.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science and Engineering

Compared to conventional materials, polymer matrix composites (PMCs) have a number of attractive properties, including light weight, easiness of installation, potential to lower system-level cost, high overall durability, and less susceptibility to environmental deterioration. However, PMCs are vulnerable to fire such that they degrade, decompose, and sometimes yield toxic gases at high temperature. The degradation and decomposition of composites lead to loss in mass, resulting in loss in mechanical strength. This research aims to improve the structural integrity of the PMCs under fire conditions by designing and optimizing a fire retardant nanopaper coating, and to fundamentally understand the thermal response and post-fire mechanical behavior the PMCs through numerical modeling. Specifically, a novel paper-making process that combined carbon nanofiber, nanoclay, exfoliated graphite nanoplatelet, and ammonium polyphosphate into a self-standing nanopaper was developed. The nanopaper was then coated onto the surface of the PMCs to improve the fire retardant performance of the material. The morphology, thermal stability, flammability, and post-fire flexural modulus of the nanopaper coated-PMCs were characterized. The fire retardant mechanism of the nanopaper coating was studied. Upon successfully improving the structure integrity of the PMCs by the nanopaper coatings, a thermal degradation model that captured the decomposition reaction of the polymer matrix with a second kind boundary condition (constant heat flux) was solved using Finite Element (FE) method. The weak form of the model was constructed by the weighted residual method. The model quantified the thermal and post-fire flexural responses of the composites subject to continuously applied heat fluxes. A temperature dependent post-fire residual modulus was assigned to each element in the FE domain. The bulk residual modulus was computed by assembling the modulus of each element. Based on the FE model, a refined Finite Difference (FD) model was developed to predict the fire response of the PMCs coated with the nanopapers. The FD model adopted the same post-fire mechanical evaluation method. However, unlike the FE model, the flow of the decomposed gas, and permeability and porosity of the composites were taken into account in the refined FD model. The numerical analysis indicated that the thickness and porosity of the composites had a profound impact on the thermal response of the composites. The research funding from the Office of Naval Research (ONR) and Federal Aviation Administration Center of Excellence for Commercial Space Transportation (FAA COE AST) is acknowledged.
ID: 031001281; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Adviser: Jihua Gou.; Title from PDF title page (viewed February 26, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 179-198).
Ph.D.
Doctorate
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering

As the use of fiber reinforced plastics increases in such industries as aerospace, wind energy, and sporting goods, factors effecting long-term durability, such as environmental exposure, are of increasing interest. The primary objectives of this study were to examine the effects of extensive environmental exposure (specifically UV radiation and moisture) on carbon/epoxy composite laminate structures and to determine the relative effectiveness of polymer-based coatings at mitigating degradation incurred due to such exposure. Carbon/epoxy composite specimens, both coated and uncoated, were subjected to accelerated weathering in which prolonged outdoor exposure was simulated by controlling the radiation wavelength (in the UV region), temperature, and humidity. Mechanical test data obtained for the uncoated specimens indicated a reduction in strength of approximately 6% after an environmental exposure duration of 750 hours. Test data revealed that no further degradation occurred with increased exposure duration. This reduction resulted from the erosion of the epoxy matrix in additional to the formation of matrix microcracks. The protective coatings evaluated were all epoxy based and included two different surfacing films applied during initial cure of the carbon/epoxy composite laminate and a chromate containing epoxy based paint primer applied after the cure was complete. Although the chromate primer performed well initially, degradation of the underlying substrate was detected with extended exposure durations. In contrast, the surfacing films provided superior protection against environmentally induced degradation. Although similar degradation attributes were identified in the surfacing film as observed in the uncoated composite, it is likely that this degradation was either confined within the surfacing film layer or only penetrated the very near surface of the carbon/epoxy substrate, as it did not result in a substantial reduction in mechanical strength.
M.S.
Department of Mechanical, Materials and Aerospace Engineering;
Engineering and Computer Science
Materials Science & Engr MSMSE

Nigeria's petroleum industry is the lynchpin of its economy. While oil has been the source of immense wealth for the nation, that wealth has come at a cost. Nigeria's main oil-producing region of the Niger River Delta has experienced tremendous environmental degradation as a result of decades of oil exploration and production. Although there have been numerous historical works on Nigeria's oil industry, there have been no in-depth analyses of the historical roots of environmental degradation over the full range of time from the colonial period to the present. This thesis contends that the environmental degradation of Nigeria's oil producing region of the Niger Delta is the direct result of the persistent non-implementation of regulatory policies by post-independence Nigerian governments working in collusion with oil multinationals. Additionally, the environmental neglect of Nigeria's primary oil-producing region is directly traceable back to the time of colonial rule. Vital to this argument is the view that the British colonial state created the economic institutions which promoted Nigerian economic dependency after independence was achieved in 1960. The weakness of Nigeria's post-colonial dependent system is exposed presently through the continued neglect of regulatory policies by successive post-colonial Nigerian governments.
M.A.
Masters
History
Arts and Humanities
History; Public History

This dissertation focuses on the scattering phenomena by well-polished optical mirror surfaces. Specifically, predicting image degradation by surface scatter from rough mirror surfaces for a two-mirror telescope operating at extremely short wavelengths (9nm~30nm) is performed. To evaluate image quality, surface scatter is predicted from the surface metrology data and the point spread function in the presence of both surface scatter and aberrations is calculated. For predicting the scattering intensity distribution, both numerical and analytic methods are considered. Among the numerous analytic methods, the small perturbation method (classical Rayleigh-Rice surface scatter theory), the Kirchhoff approximation method (classical Beckman-Kirchhoff surface scatter theory), and the generalized Harvey-Shack surface scatter theory are adopted. As a numerical method, the integral equation method (method of moments) known as a rigorous solution is discussed. Since the numerical method is computationally too intensive to obtain the scattering prediction directly for the two mirror telescope, it is used for validating the three analytic approximate methods in special cases. In our numerical comparison work, among the three approximate methods, the generalized Harvey-Shack model shows excellent agreement to the rigorous solution and it is used to predict surface scattering from the mirror surfaces. Regarding image degradation due to surface scatter in the presence of aberrations, it is shown that the composite point spread function is obtained in explicit form in terms of convolutions of the geometrical point spread function and scaled bidirectional scattering distribution functions of the individual surfaces of the imaging system. The approximations and assumptions in this formulation are discussed. The result is compared to the irradiance distribution obtained using commercial non-sequential ray tracing software for the case of a two-mirror telescope operating at the extreme ultra-violet wavelengths and the two results are virtually identical. Finally, the image degradation due to the surface scatter from the mirror surfaces and the aberration of the telescope is evaluated in terms of the fractional ensquared energy (for different wavelengths and field angles) which is commonly used as an image quality requirement on many NASA astronomy programs.
ID: 031001439; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Title from PDF title page (viewed June 26, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 223-231).
Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics

The evolution of technology brings with it the evolution of business processes. Without a doubt, technology changes how work is performed. At first glance, workplace technology appears to be a great boon to society. However, research presents opposing views on how workplace technologies impact the individual. One perspective argues that organizations utilize technology to redesign work processes, such that the worker requires less skill, autonomy, and compensation. The opposing perspective argues that organizations utilize technology to empower employees to improve efficiency and profits. This dissertation consists of three interrelated studies examining workplace technology's impact on decision makers. The first study examines the capability of an enterprise system to increase the application of scientific management techniques to middle management and, consequently, to degrade middle management's work by limiting their autonomy. The second study investigates the capability of an enterprise system to facilitate the empowerment of managers via mutual monitoring and social identification. The third study builds upon the first study by examining how limiting autonomy through technology impacts the intrinsic motivation of decision makers and, as a result, affects the decision making process. Study one applies labor process theory to explain how enterprise systems can degrade the work of middle management via scientific management techniques. The purpose of this study is to test if the expectations of labor process theory can be applied to enterprise systems. In order to test this assertion, a field survey utilizing 189 middle managers is employed and the data is analyzed using component based structural equation modeling. The results indicate that enterprise system integration increases two scientific management techniques, formalization and performance measurement, but do not reveal a significant relationship between enterprise system integration and routinization. Interestingly, the results also indicate that routinization is the only scientific management technique, of the three studied, that directly limits the autonomy of the middle managers. Although performance measurement does not reduce autonomy directly, performance measurement interacts with routinization to reduce autonomy. This study contributes to the enterprise system literature by demonstrating enterprise systems' ability to increase the degree of scientific management applied to middle management. It also contributes to labor process theory by revealing that routinization may be the scientific management technique that determines whether other control techniques are utilized in a manner consistent with labor process theory. The ability of an enterprise system to facilitate the application of Mary Parker Follett's managerial control concepts are investigated in the second study. Specifically, Follett theorizes that information sharing facilitates the internalization of group goals and empowers individuals to have more influence and be more effective. This study employs a survey of 206 managers to test the theoretical relationships. The results indicate that enterprise system integration increases information sharing in the form of mutual monitoring, consequently, leading to social identification among peer managers. Additionally, social identification among peer managers empowers managers to have more influence over the organization. The study contributes to empowerment research by acknowledging and verifying the role that social identification plays in translating an empowering work climate into empowered managers. The study's conclusion that enterprise system integration facilitates the application of Follett's managerial control concepts extends both enterprise system and managerial control literature. The third study builds upon study one by examining the affect that autonomy has upon the decision maker. This study marries self-determination theory and technology dominance theory to understand the role that self-determination, intrinsic motivation, and engagement have upon technology dominance. Self-determination theory asserts that higher degrees of self-determination increase intrinsic motivation. Furthermore, self-determination research finds that intrinsic motivation increases engagement, while technology dominance research indicates that lack of engagement is an antecedent of technology dominance. Thus, applying self-determination theory as a predictor of technology dominance suggests that autonomy and relatedness associated with a task increase the intrinsic motivation to complete that task and consequently increase engagement in the task. Task engagement, in turn, reduces the likelihood of technology dominance. The proposed theoretical model is tested experimentally with 83 junior level business students. The results do not support the theoretical model, however the findings reveal that intrinsic motivation does reduce the likelihood of technology dominance. This indicates that intrinsic motivation as a predictor of technology dominance should be further investigated. Additionally, the study contributes to technology dominance literature by exhibiting a more appropriate operationalization of the inappropriate reliance aspect of technology dominance. This dissertation reveals that various theories concerning workplace technology and management control techniques have both validity and limitations. Labor process theorists cannot assume that all technologies and management control techniques are utilized to undermine the employee's value to the organization, as Study 2 reveals that enterprise systems and mutual monitoring lead to empowered managers. Likewise, proponents of enterprise systems cannot assume that the integrated nature of enterprise systems is always utilized in an empowering manner, as Study 1 reveals the increased performance measurement through enterprise systems can be utilized to limit managers in a routinized job environment. While the third study was unable to determine that the control features in technology affect the intrinsic motivation to complete a task, the findings do reveal that intrinsic motivation is directly related to technology dominance. The findings and theoretical refinements demonstrate that workplace technology and management control have a complicated relationship with the employee and that the various theories concerning them cannot be applied universally.
Ph.D.
Doctorate
Dean's Office, Business Administration
Business Administration
Business Administration; Accounting

One of the important factors determining the lifetime of polymer electrolyte membrane fuel cells (PEMFCs) is membrane degradation and failure. The lack of effective mitigation methods is largely due to the currently very limited understanding of the underlying mechanisms for mechanical and chemical degradations of fuel cell membranes. In order to understand degradation of membranes in fuel cells, two different experimental approaches were developed; one is fuel cell testing under open circuit voltage (OCV) with bi-layer configuration of the membrane electrode assemblies (MEAs) and the other is a modified gas phase Fenton s test. Accelerated degradation tests for polymer electrolyte membrane (PEM) fuel cells are frequently conducted under open circuit voltage (OCV) conditions at low relative humidity (RH) and high temperature. With the bi-layer MEA technique, it was found that membrane degradation is highly localized across thickness direction of the membrane and qualitatively correlated with location of platinum (Pt) band through mechanical testing, Infrared (IR) spectroscopy, fluoride emission, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive spectroscopy (EDS) measurement. One of the critical experimental observations is that mechanical behavior of membranes subjected to degradation via Fenton s reaction exhibit completely different behavior with that of membranes from the OCV testing. This result led us to believe that other critical factors such as mechanical stress may affect on membrane degradation and therefore, a modified gas phase Fenton s test setup was developed to test the hypothesis. Interestingly, the results showed that mechanical stress directly accelerates the degradation rate of ionomer membranes, implying that the rate constant for the degradation reaction is a function of mechanical stress in addition to commonly known factors such as temperature and humidity. Membrane degradation induced by mechanical stress necessitates the prediction of the stress distribution in the membrane under various conditions. One of research focuses was on the developing micromechanism-inspired continuum model for ionomer membranes. The model is the basis for stress analysis, and is based on a hyperelastic model with reptation-inspired viscous flow rule and multiplicative decomposition of viscoelastic and plastic deformation gradient. Finally, evaluation of the membrane degradation requires a fuel cell model since the degradation occurs under fuel cell operating conditions. The fuel cell model included structural mechanics models and multiphysics models which represents other phenomena such as gas and water transport, charge conservation, electrochemical reactions, and energy conservation. The combined model was developed to investigate the compression effect on fuel cell performance and membrane stress distribution.
Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering PhD

Forensic anthropologists rely on forensic evidence to estimate the postmortem interval of a decedent. This may include the study of the degree of deterioration of the human body, the life stage of insects, and the degradation of associated material evidence. Material evidence comes in many forms, and certain taphonomic processes will affect the material and must be considered when making inferences about a PMI. These include variables such as the characteristics of the soil, microorganisms, and the presence of a decaying organic material. Previous research has undertaken studies in how fabric degrades over time; however, there is no standard methodology in use. The purpose of this research project is to establish a comprehensive scoring system and description standard after analyzing the degradation of four different fabric types. This will be useful for future studies in need of a standard methodology. In addition, the methods used in this project can be applied to actual forensic cases. After retrieval, the fabric type with the highest degradation was the cotton with about 1/3 of all cotton fabric swatches demonstrating more than 50% total degradation. For all fabric types, swatches that were positioned flat tended to degrade more than those that were positioned crumpled. Cotton fabric swatches degraded more in Trench 1 and Trench 2 than the Ground Surface, however, all other fabric types demonstrated slightly more degradation on the Ground Surface than the other two Areas. Soil moisture fluctuated the most on the Ground Surface while Trench 1 and Trench 2 were able to retain more water in the soil. Overall, cotton was the only fabric type to degrade significantly enough to show how it degrades over time, while the other fabric types have longer degradation intervals that must be studied further.
B.A.
Bachelors
Sciences
Anthropology

Civil Engineering
Ph.D.
Polychlorinated biphenyls (PCBs) are toxic and persistent chemicals that have been largely dispersed into the environment. The biological and abiotic transformations of PCBs often generate hydroxylated derivatives, which have been detected in a variety of environmental samples, including animal tissues and feces, water, and sediments. Because of their toxicity and widespread dispersion in the environment, hydroxylated PCBs (OH-PCBs) are today increasingly considered as a new class of environmental contaminants. Although PCBs are known to be susceptible to microbial degradation under both aerobic and anaerobic conditions, bacterial degradation of OH-PCBs has received little attention. The overall objective of this study is therefore to evaluate the transformation of mono-hydroxylated PCBs by the well characterized aerobic PCB-degrading bacterium, Burkholderia xenovorans LB400. In order to achieve our overall objective, a series of model mono-hydroxylated PCBs have been selected and they are used to determine the toxicity of hydroxylated congeners toward the bacterium B. xenovorans LB400. The biodegradation kinetics and metabolic pathways of the selected OH-PCBs by B. xenovorans LB400 are then characterized using GC/MS. To understand further the molecular basis of the metabolism of OH-PCBs by B. xenovorans LB400, gene expression analyses are conducted using reverse-transcription real-time (quantitative) polymerase chain reaction (RT-qPCR) and microarray technology. More formally, the specific aims of the proposed research are stated as follows: (1) To evaluate the toxicity of selected mono-hydroxylated derivatives of lesser-chlorinated PCBs toward the bacterium B. xenovorans LB400. (2) To assess the degradation of the selected OH-PCBs by B. xenovorans LB400. (3) To gain further understanding of the molecular bases of the metabolism of the selected OH-PCBs by B. xenovorans LB400. Three hydroxylated derivatives of 4-chlorobiphenyl and 2,5-dichlorobiphenyl, including 2'-hydroxy-, 3'-hydroxy-, and 4'-hydroxy- congeners, were significantly transformed by Burkholderia xenovorans LB400 when the bacterium was growing on biphenyl (biphenyl pathway-inducing conditions). On the contrary, only 2'-OH-4-chlorobiphenyl and 2'-OH-2,5-dichlorobiphenyl were transformed by the bacterium growing on succinate (conditions non-inductive of the biphenyl pathway). Gene expression analyses showed that only exposure to 2'-OH-4-chlorobiphenyl and 2'-OH-2,5-dichlorobiphneyl resulted in induction of key genes of the biphenyl pathway, when cells grown on succinate. These observations suggest that 2'OH-PCBs were capable of inducing the genes of biphenyl pathway. These results provide the first evidence that bacteria are able to cometabolize PCB derivatives hydroxylated on the non-chlorinated ring. Genome-wide transcriptional analyses using microarrays showed that 134 genes were differentially expressed in cells exposed to biphenyl, 2,5-dichlorobiphenyl, and 2'-OH-2,5-dichlorobiphneyl as compared to non-exposed cells. A significant proportion of differentially expressed genes were simultaneously expressed or down regulated by exposure to the three target compounds i.e., biphenyl, 2,5-DCB, and 2'-OH-2,5-DCB, which suggests that these structurally similar compounds induce similar transcriptional response of B.xenovorans LB400. Results of this study may have important implications for the natural attenuation of PCBs and fate of OH-PCBs in the environment. The recalcitrance to biodegradation and the high toxicity of some OH-PCBs may provide a partial explanation for the persistence of PCBs in the environment.
Temple University--Theses

Polychlorinated biphenyls are a ubiquitous environmental contaminant that can be found today throughout the world in soils and sediments, lakes and rivers, and flora and fauna. PCBs have percolated throughout the food chain, so that almost every human being has a detectable amount of the contaminant within their blood stream. Existing remediation methods include incineration, dredging and landfilling, and microbial degradation, but all of these methods have drawbacks that limit their effectiveness as treatment options. Recently, the use of zero-valent metals as a means of reductive dechlorination has been explored. Using a combination of zero-valent magnesium and catalytic palladium, a successful bimetallic system capable of degrading PCBs has been created and optimized. Determining the mechanism for the reductive dechlorination has proven to be an arduous task, but experimental evidence has suggested three possible radical-type mechanisms for the use Mg/Pd specifically in methanol (as compared to aqueous systems). These possible mechanisms differ in the type of hydrogen species that replaces the chlorine atom on the PCB. Thermodynamic information has also aided in narrowing down which of the suggested pathways is most likely. It appears likely that the hydrogen involved in the dechlorination has the form of a "hydride-like" radical, which is a form of electron-rich atomic hydrogen. According to the literature, Pd catalysts create this species within the first few subsurface layers of the palladium in the presence of molecular hydrogen. Further work will be necessary to confirm that the "hydride-like" radical is actually the species involved in the dechlorination.
Ph.D.
Department of Chemistry
Sciences
Chemistry PhD

Composites, though used in a variety of applications from chairs and office supplies to structures of U.S. Navy ships and aircrafts, are not all designed to hold up to extreme heat flux and high temperature. Fiber-reinforced polymeric composites (FRPC) have been proven to provide the much needed physical and mechanical properties under fire exposure. FRPC notable features are its combination of high specific tensile strength, low weight, along with good corrosion and fatigue resistance. However FRPC are susceptible to thermal degradation and decomposition, which yields flammable gas, and are thus highly combustible. This property restricts polymeric material usage. This study developed a numerical model that simulated the degradation rate and temperature profiles of a fiber-reinforced polyester resin composite exposed to a constant heat flux and hydrocarbon fire in a cone calorimeter. A numerical model is an essential tool because it gives the composite designer the ability to predict results in a time and cost efficient manner. The goal of this thesis is to develop a numerical model to simulate a zonal-layer polyester resin and fiber-glass mat composite and then validate the model with experimental results from a cone calorimeter. By inputting the thermal properties of the layered composite of alternating polymer and polymer-infused glass fiber mat layers, the numerical model is one step closer to representing the experimental data from the cone calorimeter test. The final results are achieved through adding a simulated heat flux from the pilot ignition of the degraded gas of the polyester resin. The results can be coupled into a mechanical model, which may be separately constructed for future study on the mechanical strength of composites under fire conditions.
ID: 030646184; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (M.S.M.E.)--University of Central Florida, 2011.; Includes bibliographical references (p. 53-54).
M.S.M.E.
Masters
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering; Thermo-Fluids Track

The development of thermal barrier coatings (TBCs) has been undoubtedly the most critical advancement in materials technology for modern gas turbine engines. TBCs are widely used in gas turbine engines for both power-generation and propulsion applications. Metallic oxidation-resistant coatings (ORCs) are also widely employed as a stand-alone protective coating or bond coat for TBCs in many high-temperature applications. Among the widely studied durability issues in these high-temperature protective coatings, one critical challenge that received greater attention in recent years is their resistance to high-temperature degradation due to corrosive deposits arising from fuel impurities and CMAS (calcium-magnesium-alumino-silicate) sand deposits from air ingestion. The presence of vanadium, sulfur, phosphorus, sodium and calcium impurities in alternative fuels warrants a clear understanding of high-temperature materials degradation for the development of fuel-flexible gas turbine engines. Degradation due to CMAS is a critical problem for gas turbine components operating in a dust-laden environment. In this study, high-temperature degradation due to aggressive deposits such as V2O5, P2O5, Na2SO4, NaVO3, CaSO4 and a laboratory-synthesized CMAS sand for free-standing air plasma sprayed (APS) yttria stabilized zirconia (YSZ), the topcoat of the TBC system, and APS CoNiCrAlY, the bond coat of the TBC system or a stand-alone ORC, is examined. Phase transformations and microstructural development were examined by using x-ray diffraction, scanning electron microscopy, and transmission electron microscopy. This study demonstrated that the V2O5 melt degrades the APS YSZ through the formation of ZrV2O7 and YVO4 at temperatures below 747°C and above 747°C, respectively. Formation of YVO4 leads to the depletion of the Y2O3 stabilizer and the deleterious transformation of the YSZ to the monoclinic ZrO2 phase. The investigation on the YSZ degradation by Na2SO4 and a Na2SO4 + V2O5 mixture (50-50 mol. %) demonstrated that Na2SO4 itself did not degrade the YSZ, however, in the presence of V2O5, Na2SO4 formed vanadates such as NaVO3 that degraded the YSZ through YVO4 formation at temperature as low as 700°C. The APS YSZ was found to react with the P2O5 melt by forming ZrP2O7 at all temperatures. This interaction led to the depletion of ZrO2 in the YSZ (i.e., enrichment of Y2O3 in t' -YSZ) and promoted the formation of the fluorite-cubic ZrO2 phase. Above 1250°C, CMAS deposits were observed to readily infiltrate and significantly dissolve the YSZ coating via thermochemical interactions. Upon cooling, zirconia reprecipitated with a spherical morphology and a composition that depended on the local melt chemistry. The molten CMAS attack destabilized the YSZ through the detrimental phase transformation (t -> t -> f + m). Free standing APS CoNiCrAlY was also prone to degradation by corrosive molten deposits. The V2O5 melt degraded the APS CoNiCrAlY through various reactions involving acidic dissolution of the protective oxide scale, which yielded substitutional-solid solution vanadates such as (Co,Ni)3(VO4)2 and (Cr,Al)VO4. The molten P2O5, on the other hand, was found to consume the bond coat constituents significantly via reactions that formed both Ni/Co rich phosphates and Cr/Al rich phosphates. Sulfate deposits such as Na2SO4, when tested in encapsulation, damaged the CoNiCrAlY by Type I acidic fluxing hot corrosion mechanisms at 1000°C that resulted in accelerated oxidation and sulfidation. The formation of a protective continuous Al2O3 oxide scale by preoxidation treatment significantly delayed the hot corrosion of CoNiCrAlY by sulfates. However, CoNiCrAlY in both as-sprayed and preoxidized condition suffered a significant damage by CaSO4 deposits via a basic fluxing mechanism that yielded CaCrO4 and CaAl2O4. The CMAS melt also dissolved the protective Al2O3 oxide scale developed on CoNiCrAlY by forming anorthite platelets and spinel oxides. Based on the detailed investigation on degradation of the APS YSZ and CoNiCrAlY by various corrosive deposits, an experimental attempt was carried out to mitigate the melt-induced deposit attack. Experimental results from this study demonstrate, for the first time, that an oxide overlay produced by electrophoretic deposition (EPD) can effectively perform as an environmental barrier overlay for APS TBCs. The EPD protective overlay has a uniform and easily-controllable thickness, uniformly distributed closed pores and tailored chemistry. The EPD Al2O3 and MgO overlays were successful in protecting the APS YSZ TBCs against CMAS attack and hot corrosion attack (e.g., sulfate and vanadate), respectively. Furnace thermal cyclic oxidation testing of overlay-modified TBCs on bond-coated superalloy also demonstrated the good adhesive durability of the EPD Al2O3 overlay.
Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Materials Science & Engr PhD

Triacetone triperoxide (TATP), a cyclic peroxide explosive, is frequently used by terrorists and amateur chemists due to the ease of synthesis and the availability of reagents. TATP is extremely sensitive to shock, heat, and friction thus a safe and rapid method for treating TATP is needed. The major objective of this dissertation was to develop in situ methodologies that could safely degrade TATP in various field situations. Initial studies focused on using zero-valent metals and mechanically alloyed metals to decompose TATP samples in both aqueous and organic solutions. The metal systems tested included zero-valent iron, magnesium, and magnesium bimetal, Mg/Pd. The TATP degradation reaction with the different reactive metal systems followed pseudo-first order reaction kinetics with respect to TATP concentration, and the half-lives for TATP degradation with the different reactive metal systems were calculated to test their effectiveness. The major degradation product for the TATP decomposition was determined as acetone, and carbon material balance was calculated to determine each reactive system's efficiency. The mechanism of TATP degradation using these reactive metal/bimetal particles was also explored, including reaction pathway, intermediates, and activation energies. In addition to investigating the use of zero-valent metals to degrade TATP, studies were also conducted on the use of certain metal and semimetal ionic species. Antimony (III) ions were found to have the greatest effect of TATP concentration. Various spectroscopic analyses were completed to try to characterize the reaction between the Sb[super]3+ and TATP. The Sb[super]3+ was theorized to instantaneously cleave the ring structure of the TATP molecule forming a Sb[super]3+ complex thus Sb[super]3+ systems could be used to successfully treat TATP. In order to treat TATP in the field, the metal and bimetal reactive particles were combined with an application technology, liquid membrane systems to form emulsified zero-valent metal (EZVM) systems. EZVM systems containing the reactive metal/bimetal particles were made from an organic outer layer (corn oil), water, and a nonionic surfactant (SPAN 80). The EZVM systems were observed to absorb and dissolve the TATP into the emulsion droplets where TATP degradation then occurred. EZVM systems would be ideal for degrading dry TATP residues that might be found on a carpet, door entrance, steel, concrete, plastics, etc. The other neat metal systems could also be used to degrade aqueous slurries of TATP on different surfaces if an efficient delivery system was used. Other studies focused on the use of microscale mechanically alloyed bimetals, particularly Mg/Pd, Fe/Pd, and Fe/Ni, as alternative remediation methods for the catalytic reduction of environmental contaminants: 2, 4, 6-trinitrotoluene (TNT), and 1, 3, 5-trimethylene-2, 4, 6-trinitramine (RDX) which have been found to contaminate soil and ground/surface water near industrial production sites. All the bimetals tested were shown to reduce TNT and RDX contamination in water samples with varying reactivities under ambient reaction conditions. These metal systems could be combined with EZVM or paste treatment systems (bimetal treatment systems, BTS) for the in situ treatment of these environmental contaminants.;
ID: 029094232; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 118-126).
Ph.D.
Doctorate
Department of Chemistry
Sciences

For centuries chemists have sought to improve humankind's quality of life and address many of society's most pressing needs through the development of chemical processes and synthesis of new compounds, often with phenomenal results. Unfortunately, there also are many examples where these chemicals have had unintended, detrimental consequences that are not apparent until years or decades after their initial use. There are numerous halogenated molecules in this category that are globally dispersed, resistant to natural degradation processes, bioaccumulative, and toxic to living organisms. Chemicals such as these are classified as persistent organic pollutants (POPs), and due to their negative environmental and health effects, they require safe, effective, and inexpensive means of remediation. This research focuses on the development and optimization of a reaction matrix capable of reductively dehalogenating several POPs. Initial experiments determined that powdered magnesium and 1% V/V acetic acid in absolute ethanol was the most effective system for degrading polychlorinated biphenyl (PCB), an extraordinarily recalcitrant environmental contaminant. Further studies showed that this matrix also was capable of degrading polychlorinated dibenzo-p-dioxins (PCDDs), polybrominated diphenyl ethers (PBDEs), and four organochlorine pesticides (OCPs); dieldrin, heptachlor, heptachlor epoxide, and chlordane. During this phase of testing, field samples contaminated with chlordane were washed with ethanol and this ethanol/chlordane solution was degraded using the same reaction matrix, thereby demonstrating this technology's potential for “real-world” remediation projects. Finally, a set of experiments designed to provide some insight into the mechanism of dechlorination seems to indicate that two distinct processes are necessary for degradation to occur. First, the passivated outer layer of the magnesium must be removed in order to expose the zero-valent magnesium core. Next, an electron is transferred from the magnesium to the target molecule, causing the cleavage of the halide bond and the subsequent abstraction of either a hydrogen or proton from a solvent molecule. It is anticipated that an understanding of these fundamental chemical processes will allow this system to be tailored to a wide range of complex environmental media.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

Long-term hot-carrier induced degradation of MOS devices has become more severe as the device size continues to scale down to submicron range. In our work, a simple yet effective method has been developed to provide the degradation laws with a better predictability. The method can be easily augmented into any of the existing degradation laws without requiring additional algorithm. With more accurate extrapolation method, we present a direct and accurate approach to modeling empirically the 0.18-ìm MOS reliability, which can predict the MOS lifetime as a function of drain voltage and channel length. With the further study on physical mechanism of MOS device degradation, experimental results indicated that the widely used power-law model for lifetime estimation is inaccurate for deep submicron devices. A better lifetime prediction method is proposed for the deep-submicron devices. We also develop a Spice-like reliability model for advanced radio frequency RF MOS devices and implement our reliability model into SpectreRF circuit simulator via Verilog-A HDL (Hardware Description Language). This RF reliability model can be conveniently used to simulate RF circuit performance degradation
Ph.D.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering

Fuel cells are known for their high efficiency and have the potential to become a major technology for producing clean energy, especially when the fuel, e.g. hydrogen, is produced from renewable energy sources such as wind or solar. Currently, the two main obstacles to wide-spread commercialization are their high cost and the short operational lifetime of certain components. Polymer electrolyte membrane (PEM) fuel cells have been a focus of attention in recent years, due to their use of hydrogen as a fuel, their comparatively low operating temperature and flexibility for use in both stationary and portable (automotive) applications. Perfluorosulfonic acid membranes are the leading ionomers for use in PEM hydrogen fuel cells. They combine essential qualities, such as high mechanical and thermal stability, with high proton conductivity. However, they are expensive and currently show insufficient chemical stability towards radicals formed during fuel cell operation, resulting in degradation that leads to premature failure. The incorporation of durability improving additives into perfluorosulfonic acid membranes is discussed in this work. Cerium oxide (ceria) is a well-known radical scavenger that has been used in the biological and medical field. It is able to quench radicals by facilely switching between its Ce(III) and Ce(IV) oxidation states. In this work, cerium oxide nanoparticles were added to perfluorosulfonic acid membranes and subjected to ex-situ and in-situ accelerated durability tests. The two ceria formulations, an in-house synthesized and commercially available material, were found to consist of crystalline particles of 2 – 5 nm and 20 – 150 nm size, respectively, that did not change size or shape when incorporated into the membranes. At higher temperature and relative humidity in gas flowing conditions, ceria in membranes is found to be reduced to its ionic form by virtue of the acidic environment. In ex-situ Fenton testing, the inclusion of ceria into membranes reduced the emission of fluoride, a strong indicator of degradation, by an order of magnitude with both liquid and gaseous hydrogen peroxide. In open-circuit voltage (OCV) hold fuel cell testing, ceria improved durability, as measured by several parameters such as OCV decay rate, fluoride emission and cell performance, over several hundred hours and influenced the formation of the platinum band typically found after durability testing.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

Chemistry
Ph.D.
Poly (ε-caprolactone) block poly (ethylene glycol) (PCL-b-PEG) is typical amphiphilic block copolymer that self assembles into micelles in water where the hydrolytically stable hydrophilic PEG segment forms the exterior corona and the core contains the hydrophobic degradable PCL block. Micelles from PCL-b-PEG block copolymers are among the top candidates for application as transport and delivery systems. The efficiency for micellar transported therapeutics to reach the desired site is currently limited by processes that prematurely degrade the micelle and this issue is stimulating increased effort in evaluating how micelles respond to the conditions encountered in the digestive and circulatory systems. Drug loaded micelles introduced into the blood and digestive systems encounter a wide range of conditions, enzymes and other substances that can promote micelle precipitation, degradation and premature release of therapeutics. Furthermore, PEG-b-PCL diblock copolymer micelle stability in aqueous suspension, low drug loading content and burst drug releasing are also the critical issues in drug delivery system. One central objective for this research is to identify and utilize polymer structural features that influence the hydrolytic stability of micelles toward acid, base and enzyme catalyzed hydrolysis of the polyester cores. The strategy of by preparing a set of triblock copolymers (PEG-b-PBO-b-PCL) formed by inserting a short hydrophobic non-hydrolyzable PBO segment between the PEG and PCL blocks as an approach to increase the barrier for water to reach the sensitive interface ester at the surface of the PCL core and thus increase the micelle stability at acidic aqueous medium. However, the triblock micelle doesn't significantly reduce the rate of lipase enzyme catalyzed degradation of micelle from PCL-b-PEG-OMe. Another objective for this research is to prepare PCL-b-PEG diblock copolymer micelles that have high stability in aqueous suspensions, high drug loading content and selective reactions with lipase enzymes. The working hypothesis is that the micelles with charged groups at the terminus of PEG corona will increase the micelle dispersion stability and stabilize micelles with much larger hydrophobic cores through intermicelle electrostatic repulsions. When the micelle corona and lipase enzyme have the same charge there will be an increased barrier to reaction. The comparison of micelle dispersion stabilities micelles from HO-PCL-b-PEG-CH2CH=CH, [PCL-b-PEG-RCO2]- Na+ and [PCL-b-PEG-RSO3]-Na+ demonstrates that the micelles with ionic coronas have significantly higher suspension stability. Kinetic of lipase catalyzed degradation of micelles with corona charges shows that lipases selective reaction with corona charged micelles which could be used as design feature to selectivity for therapeutic transport and release. Modification hydrophilic-hydrophobic interface and corona charges of PCL-b-PEG diblock copolymer micelle are successful chemical strategies to increase micelle stability and control acid and lipase enzymes catalytic degradation.
Temple University--Theses

Les missions franco-russes mars 94/96 comporteront plusieurs modules d'exploration de cette planete, dont un ballon thermique devant conduire une etude a haute resolution du sol a l'aide de quatre cameras ccd, ainsi qu'une cartographie radar du pergelisol. Les problemes d'imagerie lies a la prise de vue depuis un ballon libre sont etudies et une methode de detection en temps reel des degradations dans les images est proposee. Cette methode est adaptable au sol, pour le tri semi-automatique de plusieurs milliers d'images transmises. On utilise une approche fractale du comportement du module de la transformee de fourier des profils d'intensite dans les images. D'une part, cette approche permet de caracteriser simplement a l'aide de trois parametres la forme generale du module; on dispose ainsi d'un modele simple permettant de retrouver les parametres d'une degradation, si la forme generale de celle-ci est connue. D'autre part, ce modele est utilise dans une methode originale de deconvolution des images qui utilise les phases de leur transformee de fourier. Enfin, on a dresse un inventaire des differentes methodes permettant, d'abord de retrouver les parametres d'une degradation, et ensuite, de restaurer les images ayant subi ces degradations. Une preference est accordee ici aux methodes de deconvolution iteratives de richardson-lucy et de jansson-van cittert

The contamination of soils, with polycyclic aromatic hydrocarbons (PAHs), remains a widespread environmental concern. In the past two decades, many physical, chemical and biological methods have been developed and evaluated for the degradation of PAHs. However, due to their low aqueous solubility, high sorption affinity, hydrophobicity and recalcitrance, the environmental remediation of PAHs in soil continues to be economically challenging. In addition to PAH contamination, the presence of oxygenated derivatives of PAHs (OPAHs), in soils, has increasingly become a concern due to their greater toxic properties compared to parent PAH compounds. To date, no investigations on OPAH-remediation methods have been presented in the literature. The use of zero-valent metals (ZVMs) has been reported for several halogenated contaminants in solution systems, but the effectiveness of ZVM to degrade sorbed PAHs and OPAHs has been rarely addressed. This present research focuses on the development of a combined technique for the feasible desorption and degradation of PAHs and OPAHs in soils. PAH and OPAH degradation efficiency, using activated magnesium (Mg) metal combined with an ethanol-ethyl lactate cosolvent (1:1 ratio), was initially examined in soil-free systems. This metal/cosolvent system demonstrated adequate degradation (above 80%) for high-molecular-weight (HMW) PAHs, which were subsequently converted into hydroaromatic compounds; while OPAHs were degraded and converted into hydroxylated or hydrogenated derivatives. Further soil-free studies revealed that the degradation rate was affected by the surface or reactive sites of the metal and that optimum degradation efficiency were obtained with Mg ball milled with graphite (Mg/C). In a bench-scale feasibility test, the efficacy of this system was assessed on a soil spiked with a mixture of three HMW PAHs compounds and three OPAHs compounds with amounts ranging from 0.033 mmol to 0.060 mmol. The experimental results show that 2 mL of an ethanol-ethyl lactate solvent mixture resulted in 58% to 85% extraction efficiency for the selected contaminants in 1 g of spiked soil, followed by 64 - 87% degradation efficiency of the extracted contaminants with 4.11 mmol of the activated metal. This activated-Mg/cosolvent system can be considered as a promising alternative method for ex situ remediation of PAH and OPAH-contaminated soils.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

In modern turbine engines for propulsion and energy generation, thermal barrier coating (TBCs) protect hot-section blades and vanes, and play a critical role in enhancing reliability, durability and operation efficiency. In this study, thermal cyclic lifetime and microstructural degradation of electron beam physical vapor deposited (EB-PVD) Yttria Stabilized Zirconia (YSZ) with (Ni,Pt)Al bond coat and Hf- and/or Y- modified CMSX-4 superalloy substrates were examined. Thermal cyclic lifetime of TBCs was measured using a furnace thermal cycle test that consisted of 10-minute heat-up, 50-minute dwell at 1135C, and 10-minute forced-air-quench. TBC lifetime was observed to improve from 600 cycles to over 3200 cycles with appropriated Hf- and/or Y alloying of CMSX-4 superalloys. This significant improvement in TBC lifetime is the highest reported lifetime in literature with similar testing parameters. Beneficial role of reactive element (RE) on the durability of TBCS were systematically investigated in this study. Photostimulated luminescence spectroscopy (PL) was employed to non-destructively measure the residual stress within the TGO scale as a function of thermal cycling. Extensive microstructural analysis with emphasis on the YSZ/TGO interface, TGO scale, TGO/bond coat interface was carried out by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and scanning electron microscopy (STEM) as a funcion of thermal cycling including after the spallation failure. Focused ion beam in-situ lift-out (FIB-INLO) technique was employed to prepare site-specific TEM specimens. X-ray diffraction (XRD) and secondary ion mass spectroscopy (SIMS) were also employed for phase identification and interfacial chemical analysis. While undulation of TGO/bond coat interface (e.g., rumpling and ratcheting) was observed to be the main mechanism of degradation for the TBCs on baseline CMSX-4, the same interface remained relatively flat (e.g., suppressed rumpling and ratcheting) for durable TBCs on Hf- and/or Y-modified CMSX-4. The fracture paths changed from the YSZ/TGO interface to the TGO/bond coat interface when rumpling was suppressed. The geometrical incompatibility between the undulated TGO and EB-PVD YSZ lead to the failure at the YSZ/TGO interface for TBCs with baseline CMSX-4. The magnitude of copressive residual stress within the TGO scale measured by PL gradually decreased as a function of thermal cycling for TBCs with baseline CMSX-4 superalloy substrates. This gradual decrease corrsponds well to the undulation of the TGO scale that may lead to relaxation of the compressive residual stress within the TGO scale. For TBCs with Hf- and/or Y-modified CMSX-4 superalloy substrates, the magnitude of compressive residual stress within the TGO scale remained relatively constant throughout the thermal cycling, although PL corresponding to the stress-relief caused by localized cracks at the TGO/bond coat interface and within the TGO scale was observed frequently starting 50% of lifetime. A slightly smaller parabolic growth constant and grain size of the TGO scale was observed for TBCs with Hf- and/or Y- modified CMSX-4. Small monoclinic HfO2 precipitates were observed to decorate grain boundaries and the triple pointes within the alpha-Al2O3 scale for TBCs with Hf- and/or Y-modified CMSX-4 substrates. Segregation of Hf/Hf4+ at the TGO/bond coat interfaces was also observed for TBCs with Hf- and/or Y-modified CMSX-4 superalloys substrates. Adherent and pore-free YSZ/TGO interface was observed for TBCs with Hf- and/or Y-modified CMSX-4, while a significant amount of decohesion at the YSZ/TGO interface was observed for TBCs with baseline CMSX-4. The beta-NiAl(B2) phase in the (Ni,Pt)Al bond coat was observed to partially transform into gama prime-Ni3Al (L12) phase due to depletion of Al in the bond coat during oxidation. More importantly, the remaining beta-NiAl phase transformed into L10 martensitic phase upon cooling even though there was no significant difference in these phase transformations for all TBCs. Results from these microstructural observations are documented to elucidate mechanisms that suppress the rumpling of the TGO/bond coat interface, which is responsible for superior performance of EB-PVD TBCs with (Ni,Pt)Al bond coat and Hf- and/or Y-modified CMXS-4 superalloy.
Ph.D.
Department of Mechanical, Materials and Aerospace Engineering
Engineering and Computer Science
Materials Science & Engr PhD

Conventional methods of body fluid identification use labor-intensive, technologically diverse techniques that are performed in a series, not parallel, manner and are costly in terms of time and sample. Furthermore, for some frequently encountered body fluids, such as saliva or vaginal secretions, no confirmatory technique exists. Terminally differentiated cells, such as blood lymphocytes or epithelial cells lining the oral cavity, have a unique pattern of gene expression, which is evinced by the presence and relative abundance of specific mRNA species. If the type and abundance of mRNAs can be determined in a stain or tissue sample recovered at the crime scene, it would be possible to definitively identify the tissue or body fluid in question. Advantages of an mRNA-based approach, compared to conventional biochemical analysis, include greater specificity, simultaneous and semi-automated analysis though a common assay format, improved timeliness, decreased sample consumption and compatibility with DNA extraction methodologies. In this report, we demonstrate that RNA is stable in biological stains and can be recovered in sufficient quantity and quality for analysis using reverse transcriptasepolymerase chain reaction assay (RT-PCR). We have identified sets of candidate tissuespecific genes for body fluids and tissues of forensic interest, namely blood, saliva, semen, vaginal secretions, menstrual blood, urine, skin, muscle, adipose, and brain. We also report the identification of a new housekeeping gene for use in mRNA based assays. Select body fluid-specific genes have been incorporated into multiplex PCR and real-time PCR assays. These assays allow for the positive identification of blood, saliva, semen,vaginal secretions, and/or menstrual blood in a stain. The final task of this work was the molecular characterization of mRNA degradation patterns in biological stains, which not only has fundamental importance in possibly revealing mRNA degradation pathways in dried biological stains, but may ultimately lead to better assay design strategies for mRNA markers for forensic use. An mRNA-based approach described in this report could allow the facile identification of the tissue components present in a body fluid stain and could conceivably supplant the battery of serological and biochemical tests currently employed in the forensic serology laboratory.
Ph.D.
Department of Chemistry
Burnett College of Biomedical Sciences
Biomolecular Sciences: Ph.D.

Geology
M.S.
Many grasslands in arid and semi-arid regions are undergoing rapid changes in vegetation, including encroachment of woody plants and invasive grasses, which can alter the rates and patterns of fire and sediment transport in these landscapes. We investigated the spatial distribution of sediments at the scale of vegetated microsites for three years following a prescribed fire using a multiple rare earth element (REE) tracer-based approach in a shrub-grass transition zone in the northern Chihuahuan desert (New Mexico, USA). To this end, we applied REE tracers – holmium, europium, and ytterbium on shrub, grass, and bare microsites, respectively in March 2016. Soil samples were collected from both burned and control (not burned) sites before (March) and after (June) the annual windy season, from 2016 through 2018. Results indicate that although the horizontal mass flux (HMF) of wind-borne sediment increased approximately threefold in the first windy season following the fire, and the HMF of both plots were not significantly different after three windy seasons. Comparing REE concentrations in sediments from both plots over the three years and three annual windy seasons, we observed a post-fire shift in source and sink dynamics of sediments. The tracer analysis of wind-borne sediments indicated that the source of the HMF in the burned site was mostly derived from shrub microsites following the fire, whereas the bare microsites were the major contributors for aeolian sediment in control areas. The shift in sources and sinks, and the spatial homogenization of REEs indicate that the removal of shrub vegetation resulted in sediment redistribution to the bare microsites even three years after the prescribed fire. The findings of this study will improve our understanding of post-fire geomorphic processes at a microsite scale in a grassland ecosystem undergoing land degradation induced by shrub encroachment.
Temple University--Theses

Pollution from hydrofluorocarbons (HFCs) poses a serious challenge to the environmental community. Released from industrial operations, they have contaminated both the atmosphere and groundwater and are considered persistent in both media. For over the past 20 years, the practice of synthesizing HFCs as alternatives to chlorofluorocarbons (CFCs) has been conducted in an effort to reverse the effects of stratospheric ozone layer depletion. HFCs also exhibit desirable properties as precision cleaning solvents due to their low surface energies but that use has lead to releases contaminating groundwater resulting in recalcitrant pollution in the form of dense non-aqueous phase liquids (DNAPLs). Results from studies requested by the EPA have shown HFCs to exhibit developmental and neurological damage in animal life along with their impact to humans remaining not completely understood. Therefore, the potential hazards of HFCs to human health and the environment necessitates the development of an effective and environmentally responsible technology for their remediation from groundwater. The National Aeronautics and Space Administration (NASA) has employed the use of various halogenated solvents in its spacecraft cleaning operations at its facilities for many years and in that time experienced accidental releases which eventually resulted in environmental contamination. Many of the organic solvents employed in these operations consisted of halogenated compounds with most being partially chlorinated and fluorinated hydrocarbons. Through normal use and operation, releases of these materials found their way into the environs of atmosphere, soil and groundwater. Remediation of fluorinated compounds has not followed the successful path laid by clean-up technologies developed for their chlorinated counterparts. Fluorinated compounds are resistant however to those methods due to their unreactive nature stemming from the properties of the strong carbon-fluorine bond. This unique bonding property also ensures that their environmental persistence endures. One particular fluorinated groundwater contaminant, the HFC 1,1,1,2,2,3,4,5,5,5-decafluoropentane (DFP), which has been used by NASA since the late 1990's was selected as the focus of this study. For this study, various reductive metal systems were evaluated for their capability towards effective degradation of DFP. These included the metals: iron, magnesium, aluminum and zinc and several bimetallic alloys as well as on carbon support. Variations in protic solvent reaction media and acidic metal activation were also explored. The bimetallic reductive catalytic alloy Magnesium with Palladium on Carbon, Mg(Pd/C), in aqueous media proved to be the successful candidate with 100% conversion to simple hydrocarbons. Mechanistic evaluation for degradation is proposed via a series of stepwise catalytic hydrodefluorination reactions. Kinetic studies revealed degradation to obey second order reaction kinetics. Further study should be conducted optimizing an in situ groundwater delivery method for field application. Additionally, the developed technology should be assessed against other groundwater fluorocarbon pollutants; either as a method for remediating multiple fluorinated polluted sites or as a polishing agent where all other pollutants have been abated.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry

Fiber reinforced polymer (FRP) composites have become an attractive alternative to conventional methods for external-strengthening of civil infrastructure, particularly as applied to flexural strengthening of reinforced concrete (RC) members. However, durability of the bond between FRP composite and concrete has shown degradation under some aggressive environments. Although numerous studies have been conducted on concrete members strengthened with FRP composites, most of those studies have focused on the degradation of FRP material itself, relatively few on bond behavior under repeated mechanical and environmental loading. This thesis investigates bond durability under accelerated environmental conditioning of two FRP systems commonly employed in civil infrastructure strengthening: epoxy and polyurethane systems. Five environments were considered under three different conditioning durations (3 months, 6 months, and 1 year). For each conditioning environment and duration (including controls), the following were laboratory tested: concrete cylinders, FRP tensile coupons, and FRP-strengthened concrete flexural members. Numerical investigations were performed using MSC MARC finite element software package to support the outcomes of durability experimental tests. Precise numerical studies need an accurate model for the bond between FRP and concrete, a linear brittle model is proposed in this work that is calibrated based on nonlinear regression of existing experimental lap shear data. Results of tensile tests on FRP coupons indicate that both epoxy and polyurethane FRP systems do not degrade significantly under environmental exposure. However, flexural tests on the FRP strengthened concrete beams indicate that bond between FRP and concrete shows significant degradation, especially for aqueous exposure. Moreover, a protective coating suppresses the measured degradation. Also, experimental load-displacement curves for control beams show excellent agreement with numerical load-displacement curves obtained using the proposed bond model. Finally, a bond-slip model is predicted for concrete leachate conditioned beams by matching load-displacement curves for those beams with numerical load-displacement curves.
M.S.
Masters
Civil, Environmental, and Construction Engineering
Engineering and Computer Science
Civil Engineering; Structures and Geotechnical Engineering

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Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior
Despite the importance of coral reefs to humanity, these environments have been threatened throughout the world. Several factors contribute to the degradation of these ecosystems. The Maracaja? Reef Complex, in Rio Grande do Norte state is part of the Coral Reefs Environment Preservation Area in northeastern Brazil. This area has been receiving an increasing influx of tourism and the integrity of the local reefs is a matter of concern. In this study, the reef macroalgae communities were studied and compared within two areas distinguished by the presence or absence of tourism activities. Two sample sites were chosen: the first one, where diving activities are intense; and the other, where these practices do not occur. Samples were collected at both sites within a quadrate of 625 cm2 of area randomly thrown 5 times along a 10 meters transect line. Richness, Shannon-Hill diversity and Simpson dominance indices were determined based on biomass data. Similarity between sites was analyzed with Bray-Curtis similarity and distance index. Fifty-eight macroalgae species were observed, including 7 Chlorophyta, 13 Phaeophyta and 38 Rhodophyta. In the non-disturbed site, 49 species were found, while at the disturbed site, there were 42 species. Dictyotaceae and Corallinaceae were the most representative families at the non-disturbed site, and Rhodomelaceae and Dictyotaceae at the disturbed site. The non-disturbed site presented a higher biomass and the greatest richness and diversity indices. In the disturbed site the dominance index was greater and Caulerpa racemosa was the dominant species. The dendogram based on similarity index showed two major clusters, and an isolated element at the center that corresponds to a sample from the disturbed site. In the first cluster, samples from the non-impacted site were predominant and fleshy brown algae were more conspicuous. The second cluster was composed primarily of samples from the impacted site, where C. racemosa and red filamentous and erect calcareous algae associations (turf forming) were observed covering large extensions. These associations are represented by groups of algae adapted to environments where disturbances are frequent. They can grow rapidly on substrate where benthic community was removed and do not allow the establishment of other species. The results of the present study show that tourism activity is an impacting factor that has been causing shifts in macroalgae communities in the Maracaja? Reef Complex
Apesar de toda a import?ncia dos recifes para a humanidade, estes ambientes v?m sendo amea?ados em todo o mundo. Diversos s?o os fatores que podem contribuir para a degrada??o destes ambientes. Os recifes de Maracaja?, na ?rea de Preserva??o Ambiental dos Recifes de Corais, localizada no litoral norte-oriental do Rio Grande do Norte, v?m recebendo um n?mero cada vez maior de turistas, o que est? causando preocupa??es quanto a integridade do local. Neste estudo, as comunidades de macroalgas dos recifes de Maracaja? foram estudadas com a finalidade compara??o entre duas sub?reas diferenciadas pela presen?a/aus?ncia de turistas. Foram estabelecidas duas esta??es de coleta: uma (I) onde as atividades de mergulho praticadas por turistas s?o intensas e outra (II), onde estas pr?ticas n?o ocorrem. Em cada esta??o foi estabelecida transectos de 10 metros, onde foram distribu?dos de forma aleat?ria 5 quadrados (625cm2). O material coletado foi triado, identificado e teve a biomassa quantificada. A partir dos dados de biomassa foram calculados os ?ndices de riqueza, diversidade de Shannon-Hill e domin?ncia de Simpson. A similaridade entre as duas esta??es foi analisada pelo ?ndice de similaridade e dist?ncia de Bray-Curtis. Foram coletadas 58 esp?cies de macroalgas no total, sendo 7 esp?cies de Chlorophyta, 13 esp?cies de Phaeophyta e 38 esp?cies de Rhodophyta. Destas, 49 esp?cies foram encontradas na ?rea n?o impactada e 42 na ?rea impactada. Entre as fam?lias encontradas, as mais representativas na ?rea n?o impactada foram Dictyotaceae e Corallinaceae, e na ?rea impactada, Rhodomelaceae e Dictyotaceae. A ?rea n?o impactada apresentou maior biomassa e os maiores ?ndices de riqueza e diversidade. Na ?rea impactada o ?ndice de domin?ncia foi maior, sendo C. racemosa a esp?cie dominante nesta ?rea. O dendograma formado a partir do ?ndice de similaridade apresentou-se dividido em dois grandes grupos e um elemento isolado ao centro do dendograma, que corresponde a uma amostra da ?rea impactada. No primeiro agrupamento o predom?nio foi de amostras da ?rea n?o impactada, onde as algas pardas foram mais consp?cuas. Este tipo de alga se torna dominante, geralmente, em recifes onde ocorreu a redu??o do n?mero de herb?voros. O segundo agrupamento foi composto por uma maioria de amostras da ?rea impactada, onde C. racemosa e associa??es de algas filamentosas e calc?rias eretas crescendo como tapetes foram encontradas cobrindo grandes extens?es nesta ?rea. Estas associa??es compreenderam grupos de algas adaptadas a ambientes sujeitos a perturba??es freq?entes e, assim como C. racemosa, crescem rapidamente sobre espa?os rec?m desocupados nos recifes, n?o permitindo o estabelecimento de outras esp?cies. Os resultados do presente estudo demonstraram que a atividade tur?stica ? um fator impactante que t?m causado altera??es nas comunidades de macroalgas da ?rea de Preserva??o Ambiental dos Recifes de Corais

In this thesis, the parallel barrier analysis feature in the Federal Highway Administration Traffic Noise Model (FHWA TNM), which is based on RAYVERB was used to explore the effects of multiple reflections due to single and parallel barriers and the use of absorptive treatment. Database was developed from the data collected from previous research efforts was used to generate a best fit equation model that can be used as a predetermining tool to determine the magnitude of parallel barrier insertion loss. The best fit equation model was then used to test against measured/model result and TNM prediction results for its validity. Absorptive materials were also studied such that 3 top of them were selected and recommended for Florida highway barrier use. It was found that the top three absorptive treatments for use on Florida highway barriers have been determined to be cementitous material, metal wool and glass fiber. These materials can be used to reduce the sound reflections for single and parallel barriers. The developed best fit equation model from this research is Deg = -2.17NRC - CW[superscript 0.42] + 1.97eln(BH) + RH[superscript 0.29] + DBB[superscript 0.27]; the prediction results give moderately high R[superscript 2] value of 0.55 if compared to the results from database. Prediction results from best fit equation model was also found to be consistent with the results from the measure/modeled results, providing further proof of the validity of the model. However, if compared results from equation model, TNM and measured/model (measured and model compared results using ANSI method), TNM was shown to provide higher insertion loss degradation. It was found that the most effective placement of absorptive material was the pattern which covers the barrier from the bottom up; it was also found that only about 60% from the bottom of the barrier area requires covering with high NRC absorptive treatment (NRC greater than or equals to 0.8) without sacrificing insertion loss. Also, if the barrier area near the top includes an easily obtainable NRC value of 0.4, only 40% to 50% of the bottom barrier needs absorptive treatment with a higher, more expensive NRC rating. These findings can substantially reduce the cost of conventional absorptive barrier which have full coverage of high NRC absorptive treatment. This research has begun important improvements in noise barrier design, additional work can be continued to further verify all the findings in this thesis such that easier and better equation model can be developed to calculate insertion loss degradation and cheaper absorptive barrier with less absorptive material usage can be built.
M.S.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil and Environmental Engineering

In the combustion zone of industrial- and aero- gas turbines, thermomechanical fatigue (TMF) is the dominant damage mechanism. Thermomechanical fatigue is a coupling of independent creep, fatigue, and oxidation damage mechanisms that interact and accelerate microstructural degradation. A mixture of intergranular cracking due to creep, transgranular cracking due to fatigue, and surface embrittlement due to oxidation is often observed in gas turbine components removed from service. The current maintenance scheme for gas turbines is to remove components from service when any criteria (elongation, stress-rupture, crack length, etc.) exceed the designed maximum allowable. Experimental, theoretical, and numerical analyses are performed to determine the state of the component as it relates to each criterion (a time consuming process). While calculating these metrics individually has been successful in the past, a better approach would be to develop a unified mechanical modeling that incorporates the constitutive response, microstructural degradation, and rupture of the subject material via a damage variable used to predict the cumulative “damage state” within a component. This would allow for a priori predictions of microstructural degradation, crack propagation/arrest, and component-level lifing. In this study, a unified mechanical model for creep-fatigue (deformation, cracking, and rupture) is proposed. It is hypothesized that damage quantification techniques can be used to develop accurate creep, fatigue, and plastic/ductile cumulative- nonlinear- damage laws within the continuum damage mechanics principle. These damage laws when coupled with appropriate constitutive equations and a degrading stiffness tensor can be used to predict the mechanical state of a component. A series of monotonic, creep, fatigue, and tensile-hold creep-fatigue tests are obtained from literature for 304 stainless steel at 600°C (1112°F) in an air. Cumulative- nonlinear- creep, fatigue, and a coupled creep-fatigue damage laws are developed. The individual damage variables are incorporated as an internal state variable within a novel unified viscoplasticity constitutive model (zero yield surface) and degrading stiffness tensor. These equations are implemented as a custom material model within a custom FORTRAN one-dimensional finite element code. The radial return mapping technique is used with the updated stress vector solved by Newton-Raphson iteration. A consistent tangent stiffness matrix is derived based on the inelastic strain increment. All available experimental data is compared to finite element results to determine the ability of the unified mechanical model to predict deformation, damage evolution, crack growth, and rupture under a creep-fatigue environment.
Ph.D.
Doctorate
Mechanical and Aerospace Engineering
Engineering and Computer Science
Mechanical Engineering

博士
國立中興大學
生命科學系所
97
Kenting’s coral reefs face serious threats from natural disturbances and human impacts, such as typhoons, coral bleaching, overfishing, habitat loss, sedimentation, sewage discharge, eutrophication, and oil pollution over the past few decade. The combination of these factors resulted in reduced coral cover, increased abundance of macroalgae, a reduction in fish abundance, sea anemone outbreaks, and occasionally, phase shifts from coral to macroalga or sea anemone dominated reefs. This thesis is the first study to explore the attributes of community structure and functioning of Kenting coral reefs. Comparing the trophic structure and other community attributes by the Ecopath approach between marine protected area (MPA) and non MPA (nMPA) reefs revealed the trophic transfer efficiency, flow and matter cycling, resilience ability to resist the natural disturbance were greater at MPA reefs. However, fishing pressures reduced biomass of fish and other heterotrophic benthic communities, while sewage discharge led to increase growth rate and biomass in macrophytes, resulting in greater net primary production unused in the system. The analysis also revealed that MPA reefs did not only protect organisms from human activities, but also maintain community structure and normal function close to that of more pristine ecosystem. It also revealed that human activities most greatly contributed to degradation of coral reefs in Kenting. Some of the indices derived from the Ecopath approach may serve as good tools for exploring the status of coral reefs. For example, the relative ascendency ratio increased; indicating that large macrophytes underwent increases in biomass, productivity, and P/R ratios in response to eutrophication. The mean trophic level of catch, Finn’s cycling index (FCI), and average path length (APL) decreased as a result of overfishing. The Kenting coral reefs were categorized as a very limited MPA reef by a global network of MPAs study. The fishery status also revealed an overfishing of coral reefs after considering studies of long term ecological research in Kenting (Kenting-LTER) and data from fishery analyses. Comparisons with other coral reefs by Ecopath approach revealed that Nanwan Bay was similar to the unprotected Bolinao and Mahahual reefs which were characterized by high fishery catches, small fish biomass, lower mean trophic level of the catch, and extremely small cycling matter and trophic transfer efficiency. It also suggested that coral reefs of Nanwan Bay should be given overfished status, thus enhancing future protection to improve upon this currently limited MPA situation. The Kenting-LTER study and mixed trophic impacts analysis by the Ecopath approach revealed the most likely causes of coral degradation, algal increases, and sea anemone outbreaks in Nanwan Bay were sewage discharges and overfishing. The mesocosm experiments found that green alga, Codium edule, and sea anemone, Mesactinia genesis, coexisted with the live or dead coral, Acropora muricata, under low nutrients and grazing pressure. Combined nitrogen and phosphorus additions under low grazing pressure markedly increased the photosynthetic efficiencies of zooxanthellae in A. muricata, the coverage of C. edule, and the asexual reproduction of M. genesis, resulting in space competition. The hierarchy of competitive superiority under nutrient enrichment was in the order of C. edule > M. genesis > A. muricata, resulting in coral inhibited by sea anemones and algae. Coral death left more substrates open for macroalgal or sea anemone colonization, might not be prerequisites for the decline if disease, bleaching, and sedimentation follow nutrient-stimulated ecological disruption in this system. This thesis suggested that MPAs are one of best way to maintain the community structure and function of coral reef ecosystem. The set up of MPA reefs is necessary for habitat protection. However, it also revealed that enforcement and efficiency of protection are inadequate within Kenting National Park. Nanwan bay demonstrated degradation from severe human impacts, suggesting either the need for reduced fishing or the establishment of more or larger MPAs in Kenting. Fishing should be forbidden within MPAs. Government agencies can design certain fishing areas for recreation or commercial fishing and setup more buffer areas between fishing and recreation areas and MPAs, according to scientific studies and the needs of the local residents and economy of Kenting. There are too many non-point pollution sources in Kenting, a serious reduction in sewage will be essential so that interactions within coral reefs communities are not permanently altered. For a degraded coral reef, the best way to promote recovery is to reduce disturbance from human activities. Human intervention in ecological affairs such as removal of invasive sea anemones or transport of control species which will change the balance of these ecosystems is not recommended.

Worldwide, coral reefs are recognized as highly valuable ecosystems offering numerous environmental and economic services. In Saudi Arabia, the primary ecosystem service derived from coral reefs is the support of reef-based fisheries, accounting for ~75% of total fisheries landing in the kingdom. Saudi Arabian reefs experienced high fishing pressure for decades due to the growing population and associated fishing pressure. Despite the importance of the provisioning service there are limited ecosystem services valuations for this region. In the wake of a 2015 mass bleaching event, we quantified the effect of habitat degradation on the potential fisheries revenue in the central southern Red Sea. We conducted in situ reef fish surveys in 2014 and 2015 before the bleaching event and in 2019, nearly four years after the bleaching event. Using species-specific prices collected from local fish markets, we calculated values per hectare from multiple reefs in this region, to assess how the reef-based fishery was impacted by the bleaching event. A loss in live hard and soft coral cover was recorded after the bleaching event with associated shifts in the dominance of commercially important fish species. Notably, prior to bleaching, a larger proportion of the high value carnivorous species (70% carnivores, 25% herbivores) dominated the fish assemblage whereas post-bleaching reefs had a higher dominance of lower-valued herbivorous species (25% carnivores, 50% herbivores). While the total revenue was not significantly different before (7,913 USD/hectare) to after the bleaching event (6,814 USD/hectare), the loss of high value species observed suggests that if reefs continue to degrade there are potential negative flow-on effects impacting fisheries provisioning with time. Overall, an increasing percentage of live hard coral cover was positively correlated with fisheries revenue per reef, further providing evidence for the potential loss of revenue in degraded reef ecosystems in the region.

Tese de mestrado em Ecologia Marinha, apresentada à Universidade de Lisboa, através da Faculdade de Ciências, 2016
Nos últimos anos tem-se verificado um preocupante declínio dos recifes de coral, para o qual têm contribuído maioritariamente fatores antropogénicos. Isto permite que as algas ganhem uma vantagem competitiva sobre os corais, criando um desequilíbrio no ecossistema, tal como uma proliferação excessiva de parasitas. Os parasitas são parte natural e indispensável dos ecossistemas, tendo um duplo papel, já que tanto são influenciados pelo ambiente, como influenciam os hospedeiros dos quais se alimentam. Tem-se vindo a demonstrar que alguns ectoparasitas evitam ativamente o contacto com coral vivo que, com a crescente degradação dos recifes, tem vindo a diminuir, levando a uma maior proliferação destes organismos parasitários. Por outro lado, grandes densidades de peixes aumentam a proximidade entre possíveis hospedeiros, aumentando assim a probabilidade de contacto com ectoparasitas, o que tornaria espécies gregárias mais vulneráveis a infeções. De forma a contrariar o aumento da carga parasitária, especialmente de ectoparasitas, os peixes infetados podem raspar-se contra o substrato ou visitar estações de limpeza. Nestes locais residem peixes ou camarões limpadores que se alimentam dos ectoparasitas de peixes maiores, chamados “clientes”. Apesar de ainda haver alguma discussão em relação à natureza destas interações, elas são geralmente descritas como mutualistas. Assim, os ectoparasitas parecem ser uma variável fundamental para explicar as interações de limpeza, nas quais os clientes com maior carga parasitária visitam limpadores mais frequentemente e durante mais tempo. Estes clientes são, normalmente, aqueles que recebem um melhor e mais honesto serviço de limpeza. Para além de ectoparasitas, há outros tipos de vetores que podem levar os peixes a visitar estações de limpeza. Por exemplo, nas Caraíbas, os cirurgiões (Acanthurus spp.) têm sido reportados como uma família propensa ao aparecimento de manchas negras, normalmente associadas a infeções de parasitas dérmicos. O objetivo da presente dissertação foi investigar se em recifes mais degradados, ou com variações de densidade de peixes, a carga de ectoparasitas em donzelas (Stegastes diencaeus) e cirurgiões (Acanthurus tractus) seria mais elevada. Foi também investigado se os clientes mais infetados (quer por ectoparasitas, quer por parasitas dérmicos) investiam mais em comportamentos de limpeza, e se lhes era prestado um melhor serviço por parte dos limpadores. Em cinco recifes na ilha de Curaçao, Caraíbas, fizeram-se transectos de ponto-interceção para avaliar a degradação do recife. Cada ponto da comunidade bentónica foi categorizado em termos da percentagem de cobertura, em função da presença de coral vivo, areia e outros (englobando substrato favorável a ectoparasitas: coral morto, algas e esponjas). A densidade de peixes foi igualmente analisada com base em transectos, nos quais o número e espécie dos indivíduos encontrados foram registados. Os ectoparasitas de dez a onze indivíduos, tanto de donzelas como de cirurgiões, em cada recife, foram obtidos através de banhos de água doce com óleo de cravinho. Já os comportamentos ditos de limpeza (frequência de raspagens, interações e poses) e medidas de qualidade de serviço (tempo de espera na estação de limpeza, tempo de interação, e jolts) advieram do seguimento e filmagem de nove a onze indivíduos de cada espécie nos dois recifes considerados como os mais diferentes (Carmabi e Water Factory). Desses mesmos peixes, mas apenas no caso dos cirurgiões, foi registado o número de manchas negras como medida da carga de parasitas dérmicos. As diferenças entre os cinco recifes foram exploradas através de testes ANOSIM, MDS, SIMPER e ANOVA / Kruskal-Wallis, enquanto as diferenças entre os dois recifes mais distintos e entre as duas espécies de clientes foram exploradas com testes Mann-Whitney. A existência de relações entre variáveis foi analisada com recurso a correlações de Spearman. Os recifes amostrados, no que se refere ao respetivo estado, revelaram algumas diferenças, tanto na composição da comunidade bentónica como na da comunidade de peixes, especialmente entre os recifes de Carmabi e Water Factory. Water Factory foi claramente o recife com maior cobertura de coral vivo, mas também o recife com menor cobertura de substrato favorável à proliferação de parasitas em relação a Carmabi e Blue Bay Left. Water Factory e Carmabi foram os recifes com menor densidade global de peixes, mas considerando a densidade das espécies estudadas, apenas Carmabi revelou ter uma menor densidade de donzelas que Blue Bay Left. Entre os parasitas, foram identificados exemplares de três famílias: Gnathiidae (Crustacea, Isopoda), Caligidae (Crustacea, Copepoda) e Capsalidae (Platyhelminthes, Monogenea). Em todos os cinco recifes as donzelas mostraram diferenças nas três famílias de ectoparasitas, enquanto os cirurgiões mostraram diferenças apenas em duas das famílias, sendo a carga de caligídeos semelhante entre recifes. Em ambos os casos os capsalídeos mostraram resultados mais robustos, sendo em Carmabi encontradas as maiores cargas deste ectoparasita. Já a comparação entre espécies revelou que a carga de gnatiídeos foi mais elevada nas donzelas de Blue Bay Right, a carga de caligídeos foi sempre mais elevada nos cirurgiões exceto em Carmabi, que foi semelhante, e a carga de capsalídeos foi semelhante em todos os recifes. Diferentes correlações foram encontradas consoante a espécie considerada. Nas donzelas, as cargas de gnatiídeos e de caligídeos estavam negativamente correlacionadas com a cobertura de coral vivo e com a densidade da espécie, respetivamente. Nos cirurgiões, só houve uma correlação, negativa, entre cargas de gnatiídeos e a densidade global de peixes. Considerando apenas os recifes de Carmabi e Water Factory (como o mais e o menos degradado, respetivamente), a carga de ectoparasitas dos cirurgiões foi semelhante, e a das donzelas foi superior em Carmabi, maioritariamente devido aos capsalídeos. Já a frequência de manchas negras nos cirurgiões (não foi possível analisar a das donzelas) foi claramente superior em Carmabi. Em relação aos comportamentos de limpeza os cirurgiões efetuaram mais raspagens no substrato em Carmabi, e mais que as donzelas em qualquer dos recifes. Em Carmabi foram também os cirurgiões os que esperaram mais tempo para ser atendidos pelos limpadores. Os restantes comportamentos, tais como as medidas de qualidade de serviço prestado pelos limpadores, foram semelhantes entre recifes e entre espécies. Finalmente, em Carmabi, o número de manchas dos cirurgiões revelou-se positivamente correlacionado com a frequência de interações cliente-limpador. As cargas de capsalídeos, ectoparasitas com uma fase bentónica, foram superiores em Carmabi onde aparentemente havia uma pior qualidade de água e menor cobertura de coral vivo. Apenas as cargas de gnatiídeos, outro ectoparasita com fase bentónica, das donzelas foram mais elevadas em recifes com menor cobertura de coral vivo, provavelmente advindo de uma maior proximidade com substrato favorável a estes parasitas, promovido pela territorialidade destas. Os caligídeos foram encontrados sobretudo em cirurgiões, provavelmente devido ao seu comportamento gregário e móvel, utilizando mais a coluna de água na sua extensão. A densidade de peixes (de donzelas e global) mostrou ser um fator relevante, consoante a espécie (donzelas ou cirurgiões, respetivamente), na relação, negativa, com a carga de caligídeos e gnatiídeos, respetivamente. No entanto, a diferença na carga de ectoparasitas das donzelas não se revelou suficiente para uma intensificação do seu comportamento de limpeza, nem para a qualidade do serviço que lhes era prestado pelos organismos limpadores. Por outro lado, em Carmabi os cirurgiões investiram mais nos comportamentos de limpeza (raspagens e tempo de espera nas estações de limpeza) indo ao encontro da maior incidência de parasitas dérmicos (manchas negras) encontrada neste recife. Apenas no recife mais degradado a incidência de parasitas dérmicos revelou estar relacionada com um maior número de interações com limpadores. Assim, os níveis de degradação dos recifes de Curaçao parecem estar a afetar as cargas parasitárias de donzelas e cirurgiões, e essas mesmas cargas parasitárias parecem refletir-se especialmente numa intensificação do comportamento de limpeza nos cirurgiões, uma espécie aparentemente mais vulnerável. Estudos futuros deverão incluir uma abordagem mais integrativa, considerando, tanto ectoparasitas como parasitas dérmicos, a vulnerabilidade dos peixes, a frequência e qualidade dos comportamentos de limpeza, mas também medidas fisiológicas (como o nível de stress) e imunológicas. Assim, a informação resultante poderá ser importante para a monitorização da degradação dos recifes de coral e da saúde dos peixes que neles habitam, contribuindo para a conservação deste ecossistema.
Coral reefs are experiencing worrisome levels of degradation, mostly due to anthropogenic factors, leading to a disequilibrium in the ecosystem, such as an outbalanced parasite proliferation. Parasites are a natural component of the ecosystem, being influenced by the environment and in turn influencing their hosts. Conversely, higher fish density may also increase the probability of contact between parasites and possible hosts. In order to face parasitation, specifically by ectoparasites, highly infected fish may chafe against the substrate or engage in cleaning interactions more often. These so called “clients” are usually those that receive a better service by cleaners. There are also other sources of irritation that may lead fish to increase their cleaning behaviour, such may be the case of dermal parasites, visually recognized by dark blemishes on fish. The present study aimed to understand how reef degradation levels and fish density are affecting ectoparasite loads on fish, and how these ectoparasite loads, as well as dermal parasites, are affecting the clients’ cleaning behaviour. Five reefs in Curaçao were sampled for benthic community, fish density, and ectoparasite load assessment of longfin damselfish (Stegastes diencaeus) and ocean surgeonfish (Acanthurus tractus). The cleaning behaviour of the mentioned client species was also analysed in the two most different reefs. Carmabi and Water Factory revealed to be the two most different reefs in terms of benthic and fish community, and deemed as the degraded and less degraded reefs, respectively. Ectoparasites retrieved consisted in species of the Gnathiidae (Crustacea, Isopoda), Caligidae (Crustacea, Copepoda) and Capsalidae (Platyhelminthes, Monogenea) families. Except for ocean surgeonfish’s caligid loads, all ectoparasite families were found significantly different across the five sampled reefs, with fish from Carmabi experiencing the highest loads of capsalids. In four of the five reefs, ocean surgeonfish were more infected with caligids than longfin damselfish. Longfin damselfish’s gnathiid and caligid loads correlated negatively with reef live coral cover and its density, respectively. Regarding ocean surgeonfish, only gnathiid loads correlated negatively with global fish density. In terms of behavioural shifts, ectoparasite loads did not seem enough to produce changes in longfin damselfish cleaning behaviour. However, ocean surgeonfish appeared to be more vulnerable, as fish from Carmabi were observed to invest more in cleaning behaviour (chafing and waiting time at cleaning stations). This appeared to be due to significantly higher loads of dermal parasites in Carmabi (the degraded reef), where heavily infected fish interacted more often with cleaners. Future studies should include a more integrative approach, taking into consideration not only ectoparasite and dermal parasite loads, host vulnerability and cleaning behaviour, but also physiological (such as stress) and immunological measures as key variables to evaluate ecosystem disequilibrium. The resulting information may be a valuable contribution to the implementation of monitoring programs and to help in reef conservation.

In this research, I explore the changes in the functional diversity of herbivorous fishes in zones of coral reefs with different benthic composition: a zone dominated by corals, a zone dominated by algae and a transition zone in between the previous two. I choose to use functional traits which explain the feeding mechanics of this group of fish, as well their feeding rates and their previously established functional groups to understand how different assemblages of this fishes could affect their environment in different ways. I found clear differences in the functional diversity by calculating five indexes, functional dispersion (FDis), functional richness (FRic), functional divergence (FDiv), functional evenness (FEve) and functional specialization (FSpe). Each zone showed different species composition with different abundances; both parameters contribute to obtaining different values of the indexes. The coral-dominated zone showed the biggest multidimensional functional trait space (MFTS) with a value of FRic equals to 1 which means that its assemblage occupies 100% of the MFTS, while the transition zone assemblage occupied 83% and the algae-dominated zone occupied 16% of it. Thanks to this index I identified three functionally redundant species in the coral-dominated and the transition zones. The algae-dominated zone showed the lower FDis explained by the high abundance of grazers individuals. FDiv did not vary significantly between the three zones. FEve was higher in the algae-dominated zone; the index value decreased in the transition and coral-dominated zones, a similar tendency was shown by FSpe. Finally, to explore the importance of including functional diversity I made a comparison between the taxonomic and functional β-diversity. This research showed close relations of herbivorous fishes with their environment, but I could not establish if the benthic composition shapes the herbivorous fish assemblage or the other way around. This research can be a baseline to start working in functional diversity in the Red Sea coral reefs, can help to understand what to expect in the evaluation of reefs in different health state and to identify which herbivorous fish species or groups are more vulnerable and more important according to their function for coral reefs.

Testing ecological theory at macroecological scales may be useful for disentangling abiotic influences from anthropogenic disturbances, and thus provide insights into fundamental processes that structure ecological communities. In tropical coral reef systems, our understanding of community structure is limited to small-scale studies conducted in moderately degraded regions, while larger regional or ocean scale analyses have typically focused on identifying human drivers of reef degradation. In this thesis, my collaborators and I combined stable isotope specimens, underwater visual censuses, and remote sensing data from 43 Pacific islands and atolls in order to examine the relative roles of natural environmental variation and anthropogenic pressures in structuring coral reef fish and benthic communities. First, at unexploited sites on Kiritimati Atoll (Kiribati), isotope estimates indicated that trophic level increased with body size across species and individuals, while negative abundance ~ body size relationships (size spectra) revealed distinct energetic constraints between energy-competing carnivores and energy-sharing herbivores. After demonstrating size structuring of reef fish communities in the absence of humans, we then examined evidence for size-selective exploitation impacts on coral reefs across the Pacific Ocean. Size spectra 'steepened' as human population density increased and proximity to market center decreased, reflecting decreases in large-bodied fish abundance, biomass, turnover rate, and mean trophic level. Depletion of large fish abundances likely diminishes functions such as bioerosion by grazers and food chain connectivity by top predators, further degrading reef community resilience. Next, we considered the relative strengths of abiotic, biotic and anthropogenic influences in determining reef benthic state across spatial scales. We found that from fine (0.25 km2) to coarse (1,024 km2) grain scales the phase shift index (a multivariate metric of the relative cover of hard coral and macroalgal) was primarily predicted by local abiotic and bottom-up influences, such that coral-dominated reefs occurred in warm, productive regions at sites exposed to low wave energy, irrespective of grazing or human impacts. Our size- based analyses of reef fish communities revealed novel exploitation impacts at ocean-basin scales, and provide a foundation for delineating energetic pathways and feeding interactions in complex tropical food webs. Furthermore, we demonstrate that abiotic constraints underpin natural variation among fish and benthic communities of remote uninhabited reefs, emphasizing the importance of accounting for local environmental conditions when developing quantitative baselines for coral reef ecosystems.
Graduate
0329

No
Keratinous tissues such as nail, hair, horn, scales and feather have been used as a source of DNA for over 20 years. Particular benefits of such tissues include the ease with which they can be sampled, the relative stability of DNA in such tissues once sampled, and, in the context of ancient genetic analyses, the fact that sampling generally causes minimal visual damage to valuable specimens. Even when freshly sampled, however, the DNA quantity and quality in the fully keratinized parts of such tissues is extremely poor in comparison to other tissues such as blood and muscle – although little systematic research has been undertaken to characterize how such degradation may relate to sample source. In this review paper we present the current understanding of the quality and limitations of DNA in two key keratinous tissues, nail and hair. The findings indicate that although some fragments of nuclear and mitochondrial DNA appear to be present in almost all hair and nail samples, the quality of DNA, both in quantity and length of amplifiable DNA fragments, vary considerably not just by species, but by individual, and even within individual between hair types.

The article focuses on emotional labour and self-identity at the Irish-owned Aer Lingus airline from 1998 to 2008. It has been suggested that emotional labour is likely to be an increasingly important feature of frontline service jobs. However, in this case management has reduced the level of emotional labour requirement while work organization, recruitment policy and training have changed to focus on sales and lower labour costs, intensifying workloads and reducing cabin crew autonomy. Although some may suggest that a reduction in emotional labour requirement would be a positive outcome for employees, this is not how it has been perceived by some cabin crew. Long-serving cabin crew in particular see these changes as an attack on their professionalism and a challenge to their identity as skilled emotion workers.

PCBs are recalcitrant compounds of no known natural origin that persist in the environment despite their ban by the United States Environmental Protection Agency in 1979 due to negative health effects. Transport of PCBs from elastic sealants into concrete, brick, and granite structures has resulted in the need for a technology capable of removing these PCBs from the materials. This research investigated the use of a nonmetal treatment system (NMTS) and an activated metal treatment system (AMTS) for the remediation and degradation of PCBs from concrete, brick, and granite affixed with PCB-laden caulking. The adsorption of PCBs onto the components of concrete and the feasibility of ethanol washing were also investigated. NMTS is a sorbent paste containing ethanol, acetic acid, and fillers that was developed at the University of Central Florida Environmental Chemistry Laboratory for the in situ remediation of PCBs. Combining NMTS with magnesium results in an activated treatment system used for reductive dechlorination of PCBs. NMTS was applied to laboratory-prepared concrete as well as field samples by direct contact as well as by a novel sock-type delivery. The remediation of PCBs from field samples using NMTS and AMTS resulted in a 33-98% reduction for concrete, a 65-70% reduction for brick, and an 89% reduction in PCB concentration for granite. The limit of NMTS for absorption of Aroclor 1254 was found to be roughly 22,000 mg Aroclor 1254 per kg of treatment system or greater. The activated treatment system resulted in a 94% or greater degradation of PCBs after seven days with the majority of degradation occurring in the first 24 hours. The adsorption of PCBs to individual concrete components (hydrated cement, sand, crushed limestone, and crushed granite) was found to follow the Freundlich isotherm model with greater adsorption to crushed limestone and crushed granite compared to hydrated cement and sand. Ethanol washing was shown to decrease the concentration of laboratory-prepared concrete by 68% and the concentration of PCBs in the ethanol wash were reduced by 77% via degradation with an activated magnesium system.
Ph.D.
Doctorate
Chemistry
Sciences
Chemistry