As the existing steel infrastructure inevitably continues to age and deteriorate, engineers are increasingly looking for innovative and effective methods for repairing and maintaining existing structures. Structural steel components can degrade due to the surrounding environmental conditions, and are susceptible to corrosion damage when exposed to aggressive environments and deicing salts. The conventional methods for repairing steel structures can be labor-intensive and time-consuming, and add considerable weight to the existing structure. One alternative is utilizing carbon fiber reinforced polymers (CFRP). Many studies have documented the ability of CFRPs to enhance the strength of existing structures. Furthermore, CFRP offers the benefits of being non-corrosive and having a high strength-to-weight ratio. Most studies on steel strengthening have focused on the bond behavior of CFRP to steels having a smooth surface condition, which are not representative of deteriorated structures in greater need of retrofitting. Further research has examined the durability of CFRP-steel bonds relative to environmental conditions that do not reflect the service life conditions for typical applications. In this work, a comprehensive study is conducted on the effects of the surface condition and environmental exposure on the bond between CFRP and steel. The influence of corrosion and simulated corrosion pitting is evaluated to determine whether structures with non-uniform surfaces are adequate for CFRP retrofits. In addition, the durability of CFRP-steel bonded systems is investigated through laboratory hygrothermal aging and in-situ environmental conditioning to multiple environments in Virginia. The research can be useful in the development of guidelines that will assist engineers determine if a CFRP retrofit solution is applicable in a given environmental setting and appropriate for the level of deterioration of the structure. / Doctor of Philosophy / As steel structures continue to age, engineers are looking for innovative and effective methods for repairing and maintaining the existing steel infrastructure. Steel components in structures can degrade due to the surrounding environmental conditions. The conventional methods for repairing steel structures can be labor-intensive and time-consuming, and add considerable weight to the existing structure. One alternative is utilizing carbon fiber reinforced polymers (CFRP). The ability of CFRPs to enhance the strength of existing structures has been widely documented. Furthermore, CFRP offers the benefits of being non-corrosive and avoids adding considerable weight to the structure. Most studies on steel strengthening have focused on the bond behavior of CFRP to steels having a smooth surface condition, which are not representative of deteriorated structures in greater need of retrofitting. Further research has examined the durability of CFRP-steel bonds relative to environmental conditions that do not reflect the service life conditions for typical applications. In this work, a comprehensive study is conducted on the effects of the surface condition and environmental exposure on the bond between CFRP and steel. The influence of corrosion and simulated corrosion pitting is evaluated to determine whether structures with non-uniform surfaces are adequate for CFRP retrofits. In addition, the durability of CFRP-steel bonds exposed to laboratory and field conditions is investigated. The research can be useful in the development of guidelines that will assist engineers determine if the application of CFRPs retrofit solution is suitable in a given environment and appropriate for the level of deterioration of the structure.

Airborne microorganisms, such as bacteria, viruses and fungi, are abundant in the natural and built environments. This research encompasses two studies on virus aerosolization and transport in the built environment and the subsequent implications for human health. In the first study, we quantified the impact of a barrier on the spatial distribution of different-sized particles released by speaking in a poorly ventilated room. The room was outfitted with 108 passive sampling sites. The barrier resulted in an increase in 0.5 µm particles deposited on the source-side of the barrier and an increase in 0.5 µm particles at other locations 4-6 m from the source. The barrier had minor impacts on the distribution of 1, 6, 10 and 20 µm particles. The results from this study indicated that barriers may not serve as adequate protection to others in the room, depending on their locations relative to the barrier and the timescale of exposure. In the second study, we reviewed the applications of next-generation sequencing for viruses in water environments. We also characterized the occurrence of two viruses (crAssphage and SARS-CoV-2) from a local wastewater treatment plant (WWTP) in both water and air samples at two locations within the WWTP (influent and aeration basin). We found that crAssphage, a fecal indicator, was quantifiable in most air and water samples, but was not detected in control samples. SARS-CoV-2 N2 RNA was detected in a fraction of the water and air samples but was present in the control water samples, so results for this virus are confounded by laboratory contamination. We also found that there was no correlation between airborne and waterborne SARS-CoV-2 concentrations at the WWTP. A quantitative microbial risk assessment model was constructed to determine inhalation risks associated with airborne SARS-CoV-2 for WWTP operators. The probability of infection ranged from about 2.4 x 10-4 to 5.6 x 10-8 and was heavily dependent on exposure time, airborne concentration and other parameters. / Doctor of Philosophy / Airborne microorganisms, such as bacteria, viruses and fungi, are abundant in the natural and built environments. This research encompassed two studies that evaluated the impact of viruses in the built environment on public health. The first study investigated whether a barrier, like Plexiglas, could protect people from another person's exhaled particles in a poorly ventilated room. The barrier resulted in an increase in the smallest particles (0.5 µm) on the same side of the barrier as the source and an increase in these particles at other locations 4-6 m from the source, indicating that individual exposure depends on their location relative to the barrier. The barrier had minor impacts on larger particles (1, 6, 10, and 20 µm). The second study focused on viruses at wastewater treatment plants (WWTPs). As part of this study, we reviewed how one can use knowledge about the DNA and RNA of viruses in water and wastewater. We also measured the amount of two viruses (crAssphage and SARS-CoV-2) in wastewater and in air surrounding the WWTP. We detected crAssphage, a virus that infects bacteria and a marker for human activity, in most wastewater and air samples. We also detected SARS-CoV-2 in some wastewater and air samples, but this virus was also present in some control samples, so laboratory contamination was an issue. Using the concentrations of airborne SARS-CoV-2, we constructed a computational model to estimate the risk of infection for SARS-CoV-2 inhalation for WWTP employees. Our calculations indicated that the risk of infection ranged from 2.4 x 10-4 to 5.6 x 10-8 and heavily depended on parameters such as exposure time and airborne SARS-CoV-2 concentrations.

The objective of this research is to develop an integrated exposure model, which performs uncertainty analysis of exposure to the entire range of chemical contaminants in drinking water via inhalation, ingestion and dermal sorption. The study is focused on a residential environment. The various water devices considered are shower, bath, bathroom, kitchen faucet, washing machine and the dishwasher. All devices impact inhalation exposure, while showering, bathing and washing hands are considered in the analysis of dermal exposure. A set of transient mass balance equations are solved numerically to predict the concentration profiles of a chemical contaminant for three different compartments in a house (shower, bathroom and main house). Inhalation exposure is computed by combining this concentration profile with the occupancy and activity patterns of a specific individual. Mathematical models of dermal penetration, which account for steady and non-steady state analysis, are used to estimate exposure via dermal absorption. Mass transfer coefficients are used to compute the fraction of contaminant remaining in water at the time of ingestion before estimating ingestion exposure. Three chemical contaminant in water: chloroform, chromium and methyl parathion are considered for detailed analysis. These contaminants cover a wide range in chemical properties. The magnitude of overall exposure and comparison of the relative contribution of individual exposure pathways for each contaminant is evaluated. The major pathway of exposure for chloroform is inhalation, which accounts for 2/3rd of the total exposure. Dermal absorption and ingestion exposures contribute almost equally to the remaining 1/3rd of total exposure for chloroform. Ingestion accounts for about 60% of total exposure for methyl parathion and the remaining 40% of exposure is via dermal sorption. Nearly all of the total exposure (98%) for chromium is via the ingestion pathway. / Master of Science

The increased use of wood composites in building materials results in a need for a better understanding of wood adhesion. The effects of water and temperature exposure on the durability of wood products were assessed using the double-cantilever beam (DCB) method of fracture testing. The relative durability of phenol-formaldehyde (PF) and isocyanate (pMDI) adhesives was compared using a 2-hour boil test and an environmental test. The feasibility of using oriented strandboard (OSB), oriented strand lumber (OSL) and parallel strand lumber (PSL) for the DCB fracture method was assessed. The fracture resistance of PF was reduced significantly by the aging exposures. The fracture resistance of pMDI did not decrease after the 2-hour boil test. The DCB fracture method was shown to be useful with a square-grooved machined specimen using OSB and OSL. / Master of Science

Yes / Context: Vitamin D is essential for bone health in adolescence, where there is rapid bone mineral content accrual. As cutaneous sun-exposure provides vitamin D, there is no recommended oral intake for UK adolescents. Assess seasonal vitamin D status and its contributors in white Caucasian adolescents, and examine bone health in those found deficient. Design: Prospective cohort study. Setting: Six schools in Greater Manchester, UK. Participants: 131 adolescents, 12–15 years. Intervention(s): Seasonal assessment of circulating 25-hydroxyvitamin D (25OHD), personal sunexposure and dietary vitamin D. Adolescents deficient (25OHD <10 ng/mL/25 nmol/L) in ≥one season underwent dual-energy X-ray absorptiometry (lumbar spine, femoral neck), with bone mineral apparent density (BMAD) correction for size, and peripheral quantitative computed tomography (distal radius) for volumetric (v)BMD. Main Outcome Measure: Serum 25OHD; BMD. Results: Mean 25OHD was highest in September: 24.1 (SD 6.9) ng/mL and lowest in January: 15.5 (5.9) ng/mL. Over the year, 16% were deficient in ≥one season and 79% insufficient (25OHD <20 ng/mL/50 nmol/L) including 28% in September. Dietary vitamin D was low year-round while personal sun-exposure was seasonal and predominantly across the school week. Holidays accounted for 17% variation in peak 25OHD (p<0.001). Nineteen adolescents underwent bone assessment, which showed low femoral neck BMAD versus matched reference data (p=0.0002), 3 with Z≤ -2.0 distal radius trabecular vBMD. Conclusions: Sun-exposure levels failed to provide adequate vitamin D, ~one-quarter adolescents insufficient even at summer-peak. Seasonal vitamin D deficiency was prevalent and those affected had low BMD. Recommendations on vitamin D acquisition are indicated in this age-group. / The Bupa Foundation (Grant number TBF-M10-017).

Objectives: The objectives of this study were to establish the extent of dermal and respiratory exposure at selected locations at a South African platinum mine. The study included exposure to lead oxide fumes in an assay laboratory, nickel sulfate powder at a nickel sulfate crystallizer circuit and packing site and metallic copper dust whilst executing copper stripping. Methods: In an availability study, the dermal metal exposures were measured before, during and at the end of shifts. Dermal exposure samples were taken with GhostwipesTM from the dominant hand, wrist and forehead. Wipes were analyzed using Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES). Wipe samples were taken from surfaces in the workplace and analyzed according to NIOSH 9102, using ICP-AES. Personal and static inhalable dust samples were taken and the dust samples were analyzed according to NIOSH 7300, using ICP-AES. A validated questionnaire was used to evaluate self reported dermatological complaints of the workers at the fire assay laboratory and base metal recovery plant. Results: 100% of the nickel respiratory exposures and 36.8% of the lead respiratory exposures were above the occupational exposure limits (OEL). Copper respiratory exposure was present but less significant with a geometric mean of 0.071 mg m-3. All of the dermal lead measurements and the majority of the nickel and copper dermal measurements were below the limit of detection. Nickel surface contamination was the most significant and ranged between 8.430 μg cm-2 and 387.488 μg cm-2. Only 30% of the copper surface sample results were below the detection limit with a maximum surface sample of 14.41 μg cm-2. Lead surface contamination was low with 90% of the samples below the limit of detection. All of the workers at the nickel crystallizer circuit and packing site had a Dalgard score above 1.3 and therefore are at a higher risk of developing a skin disease. None of the workers at the copper stripping site had a significant Dalgard score and only one worker at the fire assay laboratory had a score above 1.3 and therefore is at a higher risk of developing a skin disease. Conclusions: Recommendations were made to lower the exposure to inhalable lead and nickel. The low lead dermal measurements may be due to adequate personal protective equipment usage and hygiene practices. Although the ethnicity of the workers may be the reason for the low incidence of dermatological complaints, the Dalgard score indicated that five workers are at risk of developing skin diseases. / Thesis (M.Sc. (Occupational Hygiene))--North-West University, Potchefstroom Campus, 2011

Opiate addiction is now a major public health problem. Pregnant women continue to use opiates during gestation; up to 5.4% of pregnant women report using illicit drugs during pregnancy. Previous studies have shown that perinatal insults and exposure to opiates such as morphine in utero can affect the development of the hypothalamic-pituitary-adrenal (HPA)-axis of the offspring and are associated with higher risk of developing neurobehavioral problems. Oxycodone, a semisynthetic putative kappa opioid receptor and partial mu opioid receptor agonist is now one of the most frequently abused pain killers during pregnancy, however limited data are available regarding whether and how perinatal oxycodone exposure (POE) alters the development and functions of the HPA-axis, the related stress axis and neurobehavioral outcomes of the offspring. Data from these experiments have provided novel evidence that POE indeed is associated with sex-specific changes in the HPA-axis in response to stress that persist beyond the neonatal period. 1) POE is associated with an increased adrenocorticotropic hormone (ACTH) response to corticotropin-releasing hormone (CRH), but not the corticosterone (CORT) response to CRH stimulation in late adolescent male offspring. 2) POE is associated with increased CORT, but not ACTH response to restraint stress test in adult female offspring. These changes in the HPA-axis response to stress may be partially explained by 1) an increase in the subpopulation of CRH neurons that also contain estrogen receptor-beta immunoreactivity following POE which then can exaggerate the stimulation of the HPA-axis, and 2) a decrease in mineralocorticoid receptor-mRNA expression in the hippocampus which may be associated with impaired negative feedback control of the HPA-axis by the limbic system. POE is also associated with cardiovascular changes in response to stress during a classical conditioning paradigm; adolescent male POE rats have a larger blood pressure increase than the control group. Although POE male rats can properly discriminate the stress versus non-stress cues in the conditioning paradigm, they do not retain this memory when retested during adulthood. When tested for learning and memory in a water maze, however, we did not find any differences between control rats and rats exposed to high dose oxycodone in utero. In addition, we demonstrated that exposure to the lower dose of oxycodone in utero is associated with hyperactivity in adult rats when tested in an open field. Our results make a significant contribution to the literature because they extend our knowledge about the effects of oxycodone on the developing brain and the resulting outcomes in animal models that are actually relevant to a current major public health problem in humans and will provide a platform for us to further study the underlying mechanisms and interventions that may mitigate these effects.

Background: Sun exposure is strongly associated with skin cancer. Sun protection to reduce harmful effects of sun exposure, including skin cancer, is encouraged. However, sun sensitivity, a possible confounder of the association between sun exposure and sun protection, is often overlooked. Objectives: This study examined how sun exposure and sun protection behaviors among indoor workers vary between sun sensitive and less sun sensitive individuals. Methods: Diaries over 45 days (August and September of 2009) from indoor workers in the Midwest were examined. Diaries included daily sun exposure, sun protection, and sun sensitivity. Sun sensitivity was measured by determination of fair and non-fair complexion, categorized based on inability to tan and tendency to sunburn. Sun exposure was compared between fair and non-fair complexion. Total exposure (sunrise to sunset) was examined, along with exposure between 10 am and 4 pm, and long exposure between 10 am and 4 pm (at least 60 minutes). Percentages of time in the sun spent practicing sun protection were reported by study participants with fair and non-fair complexion. Logistic regression was used to determine odds ratios between fair complexion and mean sun exposure and mean sun protection times. Results: Fair complexioned individuals spent less time in the sun than non-fair complexioned individuals. In addition, fair complexioned individuals spent greater percentages of time practicing sun protection behaviors while they were in the sun. They were more likely to practice sun protection behaviors related to sunscreen application and protective clothing, notably, wearing a long-sleeved shirt.Conclusion: Fair complexioned individuals spend less time in the sun and practice more sun protective behaviors than non-fair complexioned individuals. These interrelations between sun sensitivity, sun protection and amount of sun exposure suggest that controlling for potential confounding when examining one of these factors and skin cancer may be challenging.

Introdução: O câncer de mama é o segundo câncer mais incidente no mundo e o mais freqüente entre as mulheres, entretanto, sua etiologia continua desconhecida. O câncer de mama está associado a múltiplos fatores de risco, dentre eles, os fatores ocupacionais e ambientais. Objetivo: Fazer revisão bibliográfica sobre câncer de mama e exposição ocupacional e ambiental a solventes. Método: Artigos em inglês, português e espanhol foram selecionados no Pubmed e no Latin American and Caribbean Center on Health Sciences Information LILACS entre dezembro de 1981 a março de 2011. Os termos utilizados foram: breast cancer, breast neoplasm, solvent, occupational exposure and environment exposure. Foram excluídos os artigos sobre fatores genéticos, marcadores biológicos, polimorfismos, campos eletromagnéticos e nutrição. Baseado na revisão bibliográfica foi construído questionário sobre o tema e realizado teste com 29 casos e 29 controles, em um hospital da cidade de Santo André SP. Resultados: Não foram identificados artigos no Lilacs. No Pubmed foram encontrados 39 artigos. Após as exclusões 33 estudos foram selecionados: 11 casos-controle, 12 revisões, 09 coorte e 01 transversal. Em 21 artigos os autores identificaram alguma evidência de associação para os compostos alquilfenólicos, solventes orgânicos, PAHs, benzeno, estireno e percloretileno, possivelmente explicado por uma ação genotóxica direta ou através de seus metabólitos, especialmente quando as exposições ocorrem nos períodos proliferativos das células mamárias, nos carcinomas com receptores de estrógeno e progesterona negativos. Quanto ao questionário, 74 por cento dos casos e 80 por cento dos controles relataram uso de produtos químicos no trabalho sendo que 45 por cento dos casos e 55 por cento dos controles se expuseram a solventes. 62,1 por cento das participantes colaboram muito bem com a pesquisa, apesar de que, quanto ao detalhamento das respostas, 17,2 por cento das entrevistas apresentaram algumas partes duvidosas. A história ocupacional obtida através do questionário foi classificada como confiável em 67,2 por cento das entrevistas. Conclusão: Há limitadas evidências de associação entre os solventes e o câncer de mama. São necessárias mais pesquisas, com atenção para as diferenças histopatológicas, imuno-histoquímicas e genéticas das neoplasias de mama. O questionário desenvolvido precisa ser aprimorado para melhorar a confiabilidade das respostas / Introduction: Breast cancer is the most incident cancer among women in the world. However its etiology is still unknown. Multiple risk factors have been described. Occupational and environmental factors may play a role in the carcinogenesis. Objective: To make a literature review of the occupational and environmental risk factors for breast cancer. Methods: Breast cancer studies written in English, Portuguese and Spanish were identified through Pubmed and Latin American and Caribbean Center on Health Sciences Information LILACS from December 1981 to March 2011. The keywords used for the search in titles were: breast cancer, breast neoplasm, solvent, occupational exposure and environment exposure. Articles about genetic factors, biological markers, polymorphisms, electromagnetic fields and nutrition were excluded. Results: No articles were identified in Lilacs and 39 in Pubmed. After exclusions 33 studies were selected: 11 case-controls, 12 reviews, 09 cohorts and 01 cross-sectional. In 21 articles the authors identified some evidence of association for alkylphenolic compounds, organic solvents, PAH, benzene, styrene and perchloroethylene, possibly explained by a direct genotoxic action of the solvents or indirectly through their metabolites, especially when expositions happen during the proliferative period of the mammary cells, with estrogen and progesterone negative breast cancer receptors. 74 per cent cases and 80 per cent controls were exposed to chemicals in the workplace. 45 per cent cases and 55 per cent controls were exposed to solvents. 62 per cent participants collaborated very well with the research, although details regarding the responses of 17 per cent were uncertain. Occupational history obtained from the questionnaire was rated as trustworthy in 67 per cent of interviews. Conclusions: There is limited evidence of an association between solvents and breast cancer. More studies must be conducted to better understand the association between breast cancer and solvents, paying attention to hormone receptors, histopathological characteristics and BRCA1/ BRCA2 genes. The questionnaire needs to be enhanced to improve the reliability or responses

The current study explores the frequency and types of passive voice constructions found in children’s literature as compared to child directed speech (CDS). Research studies indicate that children learn to understand and produce passive voice relatively late in the language acquisition process, which some researchers attribute to the scarcity of passive voice in CDS. This study expands current knowledge of passive voice input by adding another source, children’s literature, because several studies have demonstrated that children’s books may serve as enriched sources of input for academic language. Analyses of data indicate that the amount of passive voice and the types of passive voice found in children’s literature and child directed speech are not significantly different, contradicting the idea that books contain more academic language than CDS. Further research is necessary in order to fully understand why children acquire passive voice in the late stages of language acquisition.