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The lack of biodegradability of PFAS, or per- and polyfluoroalkyl substances, is due to the presence of many strong carbon-fluorine bonds. Two common PFAS that are found in the environment are perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS). This work first studied an innovative pathway for PFAS removal through the adsorption of PFOA and PFOS (pre-concentrating the contaminants) by nanoscale zero-valent iron/reduced graphene oxide (rGO-nZVI) and their subsequent degradation via photocatalysis under UVC light. The GO that was later reduced in nanohybrid production was made utilizing a modified Hummer’s method. The rGO-nZVI nanohybrid was prepared for the first time via thermal reduction at high temperatures. Additionally, the nanohybrid was prepared using the wet chemistry method for comparison. LC/MS/MS analysis was conducted to determine the adsorption efficiencies for PFOA and PFOS using the nanohybrids and their successive removal under UVC light. Chlorinated hydrocarbons are another group of contaminants of concern that should be removed from the subsurface due to their harmful effects. In this study, a more complex mixture of the contaminants including PFAS and chlorinated hydrocarbons was investigated, which is usually found in the superfund and other contaminated sites. Considering the effectiveness of nZVI to remove chlorinated hydrocarbons from the subsurface, engineered nZVI coupled with rGO was utilized to enhance the removal efficiency of the mixture of contaminants, i.e., PFAS comingled with chlorinated hydrocarbons. The synthesized rGO-nZVI nanoparticle showed high adsorption efficiencies for both PFOA and PFOS, i.e., removal of 55.3%, 98.2%, and >99.9% of PFOA of 10, 1, and 0.1 mg/L, and 94.9%, 97.6%, and 85.0% of PFOS of 10, 1, and 0.1 mg/L, respectively, in 3 h. Later degradation of pre-concentrated PFAS under UVC light was also achieved. Using extracted rGO-nZVI, 55.1%, 77.6% of preconcentrated PFOS was degraded starting from 10, and 1 mg/L of initial concentrations before adsorption in the photoreactor at the end of 24 h. In comparison, 68.5% and 47.2% of PFOS and PFOA (starting from 1 mg/L each) was degraded, respectively, using rGO-nZVI directly under UVC light after 24 h. Moreover, it was found that rGO-nZVI had high adsorption capacity of 69.4% and 68.7% respectively for TCE and PFOA in a mixture of these contaminants. Under UVC irradiation, the preconcentrated mixture of TCE and PFOA were both degraded to below the detection limit in 21 h. It was also found that PFOA concentration dropped by 64.3% at 5 h and by 88.7% at 24 h by fresh rGO-nZVI in presence of 10 mg/L TCE. Short-chained PFCAs like PFHpA and PFHxA were found as the intermediates for PFOA degradation using rGO-nZVI under UVC light. Also, under UVC irradiation of a mixture of TCE and PFOA, TCE degradation was supported by the formation of intermediates during the reaction. Because of its composition, photocatalytic activity, large surface area, magnetic properties, and environmental friendliness, the thermal reduced rGO-nZVI particle demonstrated its potential to successfully remove PFAS and comingled chlorinated hydrocarbon from pre-concentration followed by degradation under UVC light. The nanohybrid is promising to be used to repair PFAS-contaminated water bodies.

<p>This thesis presents research documenting the effectiveness of computer-assisted cognitive remediation for patients with mood disorders. The first chapter provides an overview of cognitive impairment in patients with bipolar disorder (BD) and major depressive disorder (MDD), and a concise review of cognitive remediation in patients with schizophrenia, where the efficacy of these interventions has been reasonably well studied. The results of an analysis comparing neuropsychological test performance in patients with BD, MDD, and healthy controls is presented in Chapter 2, where we show a similar degree of deficit in both patient groups on processing speed, working memory, and mental flexibility tasks, and a greater degree of deficit in patients with BD on delayed recall and verbal fluency tasks. In Chapter 3 we present the results of our primary analysis examining the effectiveness of CACR for patients with BD and MDD; we show significant improvement on neuropsychological tests of working memory and delayed memory following remediation, and positive associations between improvement in neuropsychological test performance, and improvement in subjectively-rated cognitive and psychosocial functioning. Finally, in Chapter 4 we present functional neuroimaging evidence that shows increased activation following cognitive remediation in frontal control regions supporting working memory and in the right hippocampus supporting recollection memory. Although behavioural performance on the corresponding tasks was stable, the observation of increased activation in frontal and medial temporal brain regions following remediation is in line with our finding of improvement on neuropsychological tests of working memory and delayed recall post-training. Taken together, the results presented in this thesis provide convergent behavioural and neural evidence to demonstrate the efficacy of computer-assisted cognitive remediation for patients with mood disorders. These novel findings contribute to a growing body of literature that shows cognitive remediation to be an effective cognitive management strategy across a range of psychiatric and neurological disorders.</p> / Doctor of Philosophy (PhD)

Anthropogenic activities and natural processes over time have led to the release of toxic heavy metal contaminants into the environment. As a consequence, there is an increasing number of illnesses caused by the exposure of humans to heavy metals and metalloids. The dissertation work presented here focused on the synthesis, characterization, and understanding of the surface chemistry, as well as the photo-reactivity, of a variety of iron (oxyhydr)oxide nano-materials that have relevance for the remediation of heavy metal contaminants, such as arsenic and chromium in aqueous environments. The research focused on the photo-induced reductive dissolution of a nano-dimensioned iron oxyhydroxide, ferrihydrite, in the presence of oxalate, the photo-induced arsenite oxidation, and the simultaneous redox transformation of arsenite and chromate in the presence of ferrihydrite and another environmentally relevant iron oxyhydroxide, goethite. The photo-reductive dissolution of ferrihydrite (using simulated solar radiation) in the presence of oxalic acid was investigated with surface sensitive in situ and ex situ techniques that included attenuated total reflectance Fourier transform infrared spectroscopy. Ferrihydrite at a solution pH of 4.5 exhibited an induction period where the rate of Fe(II) release was limited by a low concentration of adsorbed oxalate due to the site-blocking of carbonate that was intrinsic to the surface of the ferrihydrite starting material. The photo-induced decarboxylation of adsorbed oxalate also ultimately led to the appearance of carbonate reaction product (distinct from carbonate intrinsic to the starting material) on the surface. Ferrihydrite that was prepared under carbonate free condition showed a rapid release of Fe(II) upon irradiation and no induction period was observed. Arsenite [As(III)] oxidation in the presence of ferrihydrite and goethite was also investigated. Ferrihydrite or goethite when exposed to As(III) in the dark led to no change in the oxidation state of As(III) reactant. However, exposure of As(III) in the presence of ferrihydrite or goethite to simulated solar light resulted in the oxidation of As(III) and a reduction of surface Fe(III) leading to an overall increase in the total As removal. At a solution pH of 5, this conversion of As(III) to As(V) on ferrihydrite resulted in the partitioning of a stoichiometric amount of Fe(II) into the aqueous phase and the majority of the As(V) product remained bound to the ferrihydrite surface. In contrast, the As(III)/goethite system showed a different photochemical behavior in the absence or presence of dissolved oxygen. Under oxic conditions, in contrast to ferrihydrite, the majority of the As(V) product was in the aqueous phase and the relative amount of aqueous Fe(II) was significantly less than in the ferrihydrite circumstance. Experimental observations suggested that in the oxic environment, Fe(II) on the goethite surface was heterogeneously oxidized to Fe(III) by dissolved oxygen resulting in the formation of reactive oxygen species that led to the further oxidation of As(III) in solution. Similarly, various experimental investigations were conducted to test the simultaneous removal of As(III) and Cr(VI) from solution. Our results suggested that a surface mediated spontaneous electron transfer between As(III) and Cr(VI) occurred in the presence of Fe- and Al-(oxy)hydroxides. Both infrared and x-ray absorption spectroscopies were conducted to get more insight into the charge transfer reaction and mechanism of electron transfer reaction. In summary, the research discussed here should help to understand the details of oxidation/reduction reactions occurring at mineral-water interfaces. Perhaps more importantly, the methodologies discussed in this dissertation could potentially be novel and eco-friendly approaches for arsenite as well as hexavalent chromium remediation. / Chemistry

Polycyclic aromatic hydrocarbons (PAHs) are highly hydrophobic and lipophilic and are readily retained by soil surfaces and organic matter. Hence, several techniques have been developed in an effort to economically and effectively remove them from soil solids. Their strong affinity to soil organic matter limits their biodegradation processes by microorganisms, making them persistent in the soil environment. Recently, the use of “small unilamellar vesicles” (SUVs), nano-scale lipid aggregates, has been proposed as a means to enhance these microbial degradations, by effectively solubilizing lipophilic PAHs from the soil solids. In this thesis, laboratory-scale batch experiments were performed to examine this potential by measuring the uptake of benzo[a]pyrene (BaP), a model PAH compound, by SUVs from a simulated soil organic matter. This environmental surface was created by coating silica (SiO2) nanospheres with a layer of poly-L-lysine, followed by humic acid, and characterized by dynamic light scattering for particle size and zeta potential values. Then, these humic acid-bound SiO2 particles were saturated with BaP and then equilibrated with SUVs. The uptake of BaP by SUVs was measured through fluorescence spectroscopy, and the average amount of BaP concentrated in the 1 mg/L humic acid-bound SiO2 particles was found to be 1.77 µg/L. After one week of equilibration with SUVs, 94.4% and 83.6% of the added BaP was solubilized by SUVs (in solutions containing 50 mg/L and 100 mg/L of vesicles, respectively), indicating an excellent ability to extract BaP from the soil organic particles. SUVs can therefore be an effective vehicle to enhance the biodegradability of PAHs in soils, with potential as an environmentally sustainable and affordable method. / Geology

Objectives: The first objective of this research was to examine whether symptom dimensions in obsessive-compulsive disorder (OCD) are associated with unique neuropsychological performance profiles. The second objective of this research was to further understand the strengths and weaknesses of two models of symptom dimensions in OCD from a quantitative perspective—conventional subtyping by overt symptom, and the core dimensions model. Finally, the third objective of this research was to investigate the efficacy and treatment acceptability of a cognitive remediation program targeting neurocognitive deficits associated with OCD. Methods: Study 1 reviewed critically studies describing the assessment of differences in neuropsychological functioning between symptom dimensions of OCD, the results of which informed succeeding studies examining: i) the characterization of symptom dimensions in OCD and; ii) the remediation of neuropsychological domains commonly affected in OCD. Accordingly, study 2 compared the suitability of two common statistical approaches, factor analysis and cluster analysis, commonly used in the existing literature to define symptom dimensions based on responses collected from the industry-standard symptom questionnaire, the Yale-Brown Obsessive Compulsive Scale (Y-BOCS), in characterizing symptom dimensions in OCD. Neuropsychological task data were then used to examine the validity of an alternative model of symptom dimensions in OCD (Study 3). Finally, we conducted a feasibility study (Study 4) examining the use of an established cognitive remediation protocol, Goal Management Training (GMT), to target the deficits in neurocognitive function identified in the preceding studies. Results: Much of the existing literature on neuropsychological task performance differences between symptom dimensions of OCD is limited by methodological issues, primarily those concerning methods for defining symptom dimensions. Here, a comparison of the two most common methods for defining dimensions revealed that neither cluster analysis nor factor analysis produced conceptually meaningful subgroups. By exemplifying differences in neuropsychological task performance between those with harm avoidance and those with incompleteness symptoms, however, concrete evidence was provided to support the core dimensions model of OCD. Pilot data point towards the feasibility and efficacy of GMT as a cognitive remediation program for OCD. Conclusions: Pursuing the definition of meaningful, distinct symptom dimensions of OCD is not recommended with the combination of current statistical practices and symptom measures. The early evidence presented here shows promise for the validity of the core dimensions model. Preliminary evidence suggests that the neuropsychological impairments observed in this population, although subtle, may be effectively addressed using Goal Management Training. / Thesis / Doctor of Philosophy (PhD)

Passive site remediation is a new concept proposed for non-disruptive mitigation of liquefaction risk at developed sites susceptible to liquefaction. It is based on the concept of slow injection of stabilizing materials at the edge of a site and delivery of the stabilizer to the target location using the natural groundwater flow. The purpose of this research was to establish the feasibility of passive site remediation through identification of stabilizing materials, a study of how to design or adapt groundwater flow patterns to deliver the stabilizers to the right place at the right time, and an evaluation of potential time requirements and costs. Stabilizer candidates need to have long, controllable gel times and low viscosities so they can flow into a liquefiable formation slowly over a long period of time. Colloidal silica is a potential stabilizer for passive site remediation because at low concentrations it has a low viscosity and a wide range of controllable gel times of up to about 100 days. Loose Monterey No. 0/30 sand samples (Dr = 22%) treated with colloidal silica grout were tested under cyclic triaxial loading to investigate the influence of colloidal silica grout on the deformation properties. Distinctly different deformation properties were observed between grouted and ungrouted samples. Untreated samples developed very little axial strain after only a few cycles and prior to the onset of liquefaction. Once liquefaction was triggered, large strains occurred rapidly and the samples collapsed within a few additional cycles. In contrast, grouted sand samples experienced very little strain during cyclic loading. What strain accumulated did so uniformly throughout loading and the samples remained intact after cyclic loading. In general, samples stabilized with 20 weight percent colloidal silica experienced very little (less than two percent) strain during cyclic loading. Sands stabilized with 10 weight percent colloidal silica tolerated cyclic loading well, but experienced slightly more (up to eight percent) strain. Treatment with colloidal silica grout significantly increased the deformation resistance of loose sand to cyclic loading. Groundwater and solute transport modeling were done using the codes MODFLOW, MODPATH, and MT3DMS. A "numerical experiment" was done to determine the ranges of hydraulic conductivity and hydraulic gradient where passive site remediation might be feasible. For a treatment are of 200 feet by 200 feet, a stabilizer travel time of 100 days, and a single line of low-head (less than three feet) injection wells, it was found that passive site remediation could be feasible in formations with hydraulic conductivity values of 0.05 cm/s or more and hydraulic gradients of 0.005 and above. Extraction wells will increase the speed of delivery and help control the down gradient extent of stabilizer movement. The results of solute transport modeling indicate that dispersion will play a large role in determining the concentration of stabilizer that will be required to deliver an adequate concentration at the down gradient edge. Consequently, thorough characterization of the hydraulic conductivity throughout the formation will be necessary for successful design and implementation of passive site remediation. The cost of passive site remediation is expected to be competitive with other methods of chemical grouting, i.e. in the range of $60 to $180 per cubic meter of treated soil, depending on the concentration of colloidal silica used. / Ph. D.

The number of college freshmen enrolled in developmental courses is an indicator that many American high school graduates are not adequately prepared for college. Research has indicated that from 30% to 69% of high school graduates who entered college are required to take at least one developmental course. The purpose of this study was to examine the high school experiences of freshmen college students, specifically, the roles their high school teachers, high school guidance counselors, the parents, and they themselves played in preparing them for college. Data were analyzed to explore differences by race (majority v. minority), gender and type of English class (regular v. developmental). The participants were freshmen students enrolled in college developmental English and general English courses at one community college and one four year college. In order to answer the research questions presented in this study, participants completed a 60-item questionnaire. Fifteen items addressed areas that the research questions investigated (i.e. role of high school teachers, guidance counselors, parents, self). The research questions were examined through a series of analysis of variance tests. Results revealed significant differences by race, gender, type of class and interactions between the effects. The data provide the basis for making recommendations to high school administrators and local school boards which, when implemented will better prepare high school students for the academic rigors of college courses. / Ed. D.

The feasibility of using ground improvement at existing highway bridges to mitigate the risk of earthquake-induced liquefaction damage has been studied. The factors and phenomena governing the performance of the improved ground were identified and clarified. Potential analytical methods for predicting the treated ground performance were investigated and tested. Key factors affecting improved ground performance are the type, size, and location of the treated ground. The improved ground behavior is influenced by excess pore water pressure migration, ground motion amplification, inertial force phasing, dynamic component of liquefied soil pressure, presence of a supported structure, and lateral spreading forces. Simplified, uncoupled analytical methods were unable to predict the final performance of an improved ground zone and supported structure, but provided useful insights. Pseudostatic stability and deformation analyses can not successfully predict the final performance because of their inability to adequately account for the transient response. Equivalent-linear dynamic response analyses indicate that significant shear strains, pore water pressures and accelerations will develop in the improved ground when the treated-untreated soil system approaches resonance during shaking. Transient seepage analyses indicate that evaluating pore pressure migration into a three-dimensional improved zone using two-dimensional analyses can underestimate the pore pressures in the zone. More comprehensive, partially-coupled analyses performed using the finite difference computer program FLAC provided better predictions of treated ground performance. These two-dimensional, dynamic analyses based on effective stresses incorporated pore pressure generation, non-linear stress-strain behavior, strength reduction, and groundwater flow. Permanent movements of structures and improved soil zones were predicted within a factor of approximately two. Predictions of ground accelerations and pore water pressures were less accurate. Dynamic analyses were performed with FLAC for an example bridge pier and stub abutment on an approach embankment supported on shallow foundations and underlain by thick, liquefiable soils with and without improved ground zones. Ground improvement that restricted movements of the pier and stub abutment to tolerable levels included improved zones of limited size extending completely through the underlying liquefiable soils and formed through densification by compaction grouting or cementation by chemical grouting or jet grouting. A buttress fill at the abutment was unsuccessful. / Ph. D.