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Title: STATIC STRESS ANALYSIS OF CHAIN LINKS USING A FINITE-ELEMENT METHOD.
Creator: TSENG, HUAN-SHOO HANS., Florida Atlantic University, Stevens, Karl K., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: A static stress analysis of a common chain link and a pear-shaped nng ivas performed using the finite element structural analysis program SAP IV. The required finite element mesh and loading inputs were generated by the pre-processing program PRE-SAP- LINK. This procedure was used to determine the midplane stresses and displacements in a link and ring of typical sizes and subject to concentrated fcrces. Stress distributions and displacements were drawn by hand and by using a Tektronix 4662...
Show moreA static stress analysis of a common chain link and a pear-shaped nng ivas performed using the finite element structural analysis program SAP IV. The required finite element mesh and loading inputs were generated by the pre-processing program PRE-SAP- LINK. This procedure was used to determine the midplane stresses and displacements in a link and ring of typical sizes and subject to concentrated fcrces. Stress distributions and displacements were drawn by hand and by using a Tektronix 4662 Interactive Digital Plotter, respectively. The results obtained show that for both link and ring, the numerically largest principal stress and maximum in-plane shear stress occur on the element directly under an applied load . The entire procedure was verified by comparing the results obtained for the common link with experimental results in the literature and with analytical results obtained using a mechanics of materials approach. All of the results were in close agreement.
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Date Issued: 1980
PURL: http://purl.flvc.org/fcla/dt/14023
Subject Headings: Stress concentration
Format: Document (PDF)

Title: Stress corrosion cracking susceptibility of engineering alloys in acidified seawater.
Creator: Campaignolle, Xavier., Florida Atlantic University, Lipka, Stephen M.
Abstract/Description: Experiments were conducted to determine the stress corrosion cracking (SCC) susceptibility of various corrosion-resistant alloys which included: 17-4 PH, INCONEL 718 and A286. These alloys were studied for different aging (heat) treatments. Slow strain rate tests (extension rate = 4.7 x 10^-5 mm/s) were performed on each alloy in four different environments; including air and natural seawater acidified with reagent grade hydrochloric acid to a pH of 0.1, 1 and 3. During the experiments, the...
Show moreExperiments were conducted to determine the stress corrosion cracking (SCC) susceptibility of various corrosion-resistant alloys which included: 17-4 PH, INCONEL 718 and A286. These alloys were studied for different aging (heat) treatments. Slow strain rate tests (extension rate = 4.7 x 10^-5 mm/s) were performed on each alloy in four different environments; including air and natural seawater acidified with reagent grade hydrochloric acid to a pH of 0.1, 1 and 3. During the experiments, the load versus time and the open circuit potential were monitored. Various parameters such as time-to-failure, energy-to-failure, maximum or failure stress and reduction-in-area were calculated in order to determine SCC susceptibility. Fractography using SEM was conducted to confirm whether any SCC occurred and, if so, to identify its mode (intergranular or transgranular). Limited potentiodynamic studies were also completed to evaluate the passive behavior of these alloys. The results are discussed in terms of the SCC susceptibility and the nature of the cracking. An attempt was also made to correlate alloy microstructure, slow strain rate test parameters and passivation behavior with SCC susceptibility.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14756
Subject Headings: Stress corrosion, Alloys--Stress corrosion, Metals--Stress corrosion
Format: Document (PDF)

Title: Debonding failure analysis of overmolded pad array carrier (OMPAC) integrated circuit packages.
Creator: Hunt, Stephen Douglas., Florida Atlantic University, Carlsson, Leif A.
Abstract/Description: Recently developed electronic packages called Overmolded Pad Array Chip Carrier (OMPAC) IC packages frequently fail at the interface between the overmold compound and the substrate. In this study, this generic type of structure was evaluated by a combination of experimental and analytical methods. Model specimens representative of OMPAC structures were designed, manufactured and tested to failure. Detailed finite element models of the specimens were developed and analyses conducted to...
Show moreRecently developed electronic packages called Overmolded Pad Array Chip Carrier (OMPAC) IC packages frequently fail at the interface between the overmold compound and the substrate. In this study, this generic type of structure was evaluated by a combination of experimental and analytical methods. Model specimens representative of OMPAC structures were designed, manufactured and tested to failure. Detailed finite element models of the specimens were developed and analyses conducted to calculate debond stresses. Analytical methods were refined to include the effect of stress singularities. Stress results were averaged over a distance of.010 in. around the stress singularities to capture the intensity of the stress. These results were used in a combined stress failure criterion to calculate interfacial strengths based on macroscopic failure loads. The interfacial strengths were found to approach, but not exceed, those of the bulk overmold compound.
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Date Issued: 1991
PURL: http://purl.flvc.org/fcla/dt/14778
Subject Headings: Thermal stresses, Integrated circuits
Format: Document (PDF)

Title: Hybrid method of finite element and photoelasticity to analyze stress concentrations on threaded cylinders.
Creator: Gonella, Julio Cesar., Florida Atlantic University, Case, Robert O.
Abstract/Description: This paper studies the stress concentrations at the root of the threads of a cylinder. A photoelastic analysis using the stress freezing procedure is used to calculate the stress along the cylinder and the stress concentrations at the root of the threads. These values are compared to that of similar cylinders with different threaded configurations. A finite element model is built by using the photoelastic data to find a suitable load distribution along the threaded region. The finite element...
Show moreThis paper studies the stress concentrations at the root of the threads of a cylinder. A photoelastic analysis using the stress freezing procedure is used to calculate the stress along the cylinder and the stress concentrations at the root of the threads. These values are compared to that of similar cylinders with different threaded configurations. A finite element model is built by using the photoelastic data to find a suitable load distribution along the threaded region. The finite element model predicted results similar to the photoelastic analysis and showed a method of reducing the stress concentrations on the threads by redesigning a pressure ring on the cylinder.
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Date Issued: 1990
PURL: http://purl.flvc.org/fcla/dt/14581
Subject Headings: Stress concentration, Cylinders
Format: Document (PDF)

Title: Environmental cracking susceptibility of austenitic stainless steel alloys in acidified seawater.
Creator: Poulassichidis, Antonios N., Florida Atlantic University, Lipka, Stephen M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The stress corrosion cracking susceptibility of austenitic stainless steels SS304L, SS316L and SS904L was studied in an acidified seawater environment by slow strain rate testing at 24, 38 and 66$\sp\circ$C. Fractographic evidence of SCC susceptibility was obtained using scanning electron microscopy. The degree of susceptibility to SCC for each alloy in these environments is discussed based on the mechanical parameters, fractography and anodic polarization behavior. The results showed that...
Show moreThe stress corrosion cracking susceptibility of austenitic stainless steels SS304L, SS316L and SS904L was studied in an acidified seawater environment by slow strain rate testing at 24, 38 and 66$\sp\circ$C. Fractographic evidence of SCC susceptibility was obtained using scanning electron microscopy. The degree of susceptibility to SCC for each alloy in these environments is discussed based on the mechanical parameters, fractography and anodic polarization behavior. The results showed that SS904L performed better than SS304L and SS316L in the aforementioned environments.
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Date Issued: 1994
PURL: http://purl.flvc.org/fcla/dt/15071
Subject Headings: Stress corrosion, Seawater corrosion, Alloys--Stress corrosion
Format: Document (PDF)

Title: Long-term stress-induced changes in brain monoamines of the gray snapper, Lutjanus griseus. Neurotransmitters as indicators of physiological stress.
Creator: Brager, Darrin H., Florida Atlantic University, Lutz, Peter L.
Abstract/Description: It is well established that altered neurotransmitter levels have long been associated with stress in many mammals. The purpose of this study was to determine if changes in the brain tissue concentration and/or turnover rates of the monoamine neurotransmitters could be used as an early indicator of physiological stress for fish in different aquatic ecosystems. Gray snapper, Lutjanus griseus, were collected from two sites, a pristine (control) and a polluted (experimental) site, classification...
Show moreIt is well established that altered neurotransmitter levels have long been associated with stress in many mammals. The purpose of this study was to determine if changes in the brain tissue concentration and/or turnover rates of the monoamine neurotransmitters could be used as an early indicator of physiological stress for fish in different aquatic ecosystems. Gray snapper, Lutjanus griseus, were collected from two sites, a pristine (control) and a polluted (experimental) site, classification based upon the hydrocarbon content of their sediment. The brains were quickly removed and dissected into three regions: frontal lobes, hypothalamus, and brain stem which were later analyzed for using high performance liquid chromatography. A decrease in brain tissue norepinephrine and dopamine concentration in the frontal lobes and hypothalamus was observed in individuals collected from the polluted site. No significant difference in either norepinephrine or dopamine concentration was present in the brain stem. Despite a decrease in dopamine levels, there was no significant change in dopamine turnover. There was a significant decrease in serotonin concentration in the hypothalamus at the polluted site. There was an increase in serotonergic activity in the hypothalamus and brain stem at the polluted site. A significant decrease in the weight of the hypothalamus in fish from the polluted site was also observed. These results suggest that a change in brain monoamines can be used as a early indicators of chronic environmental stress.
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Date Issued: 1997
PURL: http://purl.flvc.org/fcla/dt/15458
Subject Headings: Neurotransmitters, Gray snapper--Effect of stress on, Stress (Physiology)
Format: Document (PDF)

Title: Effect of strain rate and temperature on the stress corrosion cracking tendency of engineering alloys in acidified seawater.
Creator: Kundalgurki, Srivatsa G., Florida Atlantic University, Lipka, Stephen M., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The stress corrosion cracking (SCC) tendencies of several engineering alloys were studied in an acidified seawater environment as a function of applied strain rate and electrolyte temperature. The selected alloys included austenitic stainless steels 304L, 316L, 904L and A-286 (an iron-based superalloy at two heat treatments yielding ultimate tensile strengths of 130 and 200 ksi), Inconel 718 (220 ksi ultimate tensile strength) and Hastelloys C-22 and C-276. The slow strain rate test technique...
Show moreThe stress corrosion cracking (SCC) tendencies of several engineering alloys were studied in an acidified seawater environment as a function of applied strain rate and electrolyte temperature. The selected alloys included austenitic stainless steels 304L, 316L, 904L and A-286 (an iron-based superalloy at two heat treatments yielding ultimate tensile strengths of 130 and 200 ksi), Inconel 718 (220 ksi ultimate tensile strength) and Hastelloys C-22 and C-276. The slow strain rate test technique was used to evaluate the SCC strain rate dependency of each alloy at extension rates of 4.7 x 10^-6, 4.7 x 10^-4 and 4.7 x 10^-3 mm/sec. The effect of electrolyte temperature was evaluated at 38C and 60C at a single extension rate of 4.7 x 10^-5 mm/sec. Control specimens were tested in a laboratory air environment at an extension rate of 4.7 x 10^-5 mm/sec. Various mechanical parameters of the specimens tested in the corrosive medium were compared with those of control specimens to quantify the degree of cracking. Fractographic evidence of SCC was obtained using scanning electron microscopy (SEM). An attempt was made to correlate SCC tendency with the alloy's passivation kinetics and microstructure. Atmospheric exposure testing was performed in a simulated space shuttle launch pad environment for selected alloys.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/14853
Subject Headings: Alloys--Stress corrosion, Stress corrosion, Sea-water corrosion
Format: Document (PDF)

Title: PREVALENCE, SOURCES, AND SYMPTOMS OF TEACHER STRESS AMONG PUBLIC SCHOOL TEACHERS IN FLORIDA.
Creator: BUCKLEW, NANCY DEZZUTTI, Florida Atlantic University, Weppner, Daniel B.
Abstract/Description: Purpose. The purpose of this study was to determine the prevalence, sources, and symptoms of teacher stress among public school teachers in Florida. Procedure. Stress was defined as a response syndrome of negative affects resulting from aspects of the teacher's job and mediated by the perception that the demands constitute a threat to self-esteem and by coping mechanisms activated to reduce the perceived threat. The instrument used in collecting the data for this study was a mail...
Show morePurpose. The purpose of this study was to determine the prevalence, sources, and symptoms of teacher stress among public school teachers in Florida. Procedure. Stress was defined as a response syndrome of negative affects resulting from aspects of the teacher's job and mediated by the perception that the demands constitute a threat to self-esteem and by coping mechanisms activated to reduce the perceived threat. The instrument used in collecting the data for this study was a mail questionnaire, with a scale ranging from zero to four, for assessing the intensity of each item. The questionnaire consisted of biographical and school environmental characteristics, fifty possible sources of teacher stress, a general stress question, and sixteen possible symptoms of teacher stress. As a pilot study, the questionnaire was administered to a group of public school teachers in Palm Beach County for the purpose of examining each item for clarity. Items found to be ambiguous were revised or deleted. The 325 sample population was randomly selected from the Florida Teaching Profession/National Education Association membership. The mail questionnaire had a 78 percent response for a total of 248 respondents. The data were transformed to computer cards and submitted for statistical analysis through the Florida Atlantic University Computer Center, Boca Raton, Florida. Means, rank-order, T-tests, analysis of variance, and factor analysis were applied to the data for the purpose of determining the level of significance in deciding to reject or accept the research hypotheses at the .05 level. Conclusions and Recommendations. It is concluded from the results of the analysis that teacher stress is prevalent in Florida. Forty-one percent of the respondents reported being a teacher was either very stressful or extremely stressful. Self-reported teacher stress appeared to be similarly distributed for the biographical and school environmental characteristics. Pupil misbehavior accounted for the largest percentage of sources of stress with high means. The priority source of stress as perceived by the teachers was inadequate teaching salaries. Teachers, regardless of biographical or environmental characteristics, appear to share common perceptions concerning the sources and symptoms of teacher stress. Recommendations for reducing and/or dealing with stress are presented with suggestions ranging from inservice programs, a teacher social support system to administrative consistency and teacher bargaining unit concerns.
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Date Issued: 1981
PURL: http://purl.flvc.org/fcla/dt/11776
Subject Headings: Job stress
Format: Document (PDF)

Title: A STUDY OF STRESS CORROSION CRACKING IN 7079-T651 ALUMINUM.
Creator: FINNEGAN, JOHN EDMUND., Florida Atlantic University, Hartt, William H.
Abstract/Description: This study investigated the stress corrosion cracking behavior of aluminum alloy 7079 - T651 in two corrosive environments, sea water and a 3% NaCl-distilled water solution. Self stressing, double cantilever beam specimens were employed; and these were stressed at various levels, exposed in one of the two test environments and crack extension monitored as a function of time. Equations for the plane strain stress intensity factor (K1) were compared and evaluated, with respect to stress...
Show moreThis study investigated the stress corrosion cracking behavior of aluminum alloy 7079 - T651 in two corrosive environments, sea water and a 3% NaCl-distilled water solution. Self stressing, double cantilever beam specimens were employed; and these were stressed at various levels, exposed in one of the two test environments and crack extension monitored as a function of time. Equations for the plane strain stress intensity factor (K1) were compared and evaluated, with respect to stress intensities calculated from compliance measurements. Results suggest that stress intensity is not the only important variable controlling crack growth rate and a time dependent cracking mechanism may govern a portion of crack growth.
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Date Issued: 1975
PURL: http://purl.flvc.org/fcla/dt/13730
Subject Headings: Aluminum--Corrosion, Stress corrosion
Format: Document (PDF)

Title: STRESS CORROSION CRACKING OF 7079-T651 ALUMINUM IN RESPONSE TO A CONSTANT STRESS INTENSITY.
Creator: SCOTT, DARWIN HAROLD, II., Florida Atlantic University, Hartt, William H., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Double cantilever beam specimens of 7079-T651 aluminum were subjected to low constant stress intensities in a sea water environment to determine the stress corrosion cracking response. In addition to a constant stress intensity some specimens were subjected to controlled, constant potentials. Despite the fact that all tests were in Region I of the crack growth rate-stress intensity curve, where the former has been projected to be very dependent upon the latter, a unique relationship between...
Show moreDouble cantilever beam specimens of 7079-T651 aluminum were subjected to low constant stress intensities in a sea water environment to determine the stress corrosion cracking response. In addition to a constant stress intensity some specimens were subjected to controlled, constant potentials. Despite the fact that all tests were in Region I of the crack growth rate-stress intensity curve, where the former has been projected to be very dependent upon the latter, a unique relationship between stress intensity and crack growth rate was not always indicated. Therefore, some variable other than stress intensity is assumed to control crack growth, particularly for the first several hundred hours of exposure. The observed behavior is discussed in terms of accepted theories of stress corrosion cracking in high strength aluminum alloys, including electrochemical dissolution and hydrogen embrittlement.
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Date Issued: 1977
PURL: http://purl.flvc.org/fcla/dt/13878
Subject Headings: Stress corrosion, Aluminum--Corrosion
Format: Document (PDF)

Title: Some corrosion problems associated with underwater turbines.
Creator: Miglis, Yohann., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: This thesis deals with corrosion problems of underwater turbines in marine environment. The effect of a tensile stress on the uniform corrosion rate of a metal bar is studied, and an analytical model predicting the time of service of a bar under a tensile load in a corrosive environment is proposed. Stress corrosion relationships are provided for different type of alloys, and different types of relationships. Dolinskii's and Gutman's models are studied and extended to a general order...
Show moreThis thesis deals with corrosion problems of underwater turbines in marine environment. The effect of a tensile stress on the uniform corrosion rate of a metal bar is studied, and an analytical model predicting the time of service of a bar under a tensile load in a corrosive environment is proposed. Stress corrosion relationships are provided for different type of alloys, and different types of relationships. Dolinskii's and Gutman's models are studied and extended to a general order polynomial, along with a Least Square and Spline Interpolation of the experimental data. In a second part, the effect of the passive film, delaying the initiation of the corrosion process, is studied. Finally, an algorithm predicting the time of service of a cracked bar is provided, using the stress corrosion assumption, along with a validation using experimental data.
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Date Issued: 2012
PURL: http://purl.flvc.org/FAU/3342238
Subject Headings: Turbines, Stress corrosion, Testing, Computational fluid dynamics, Stress corrosion, Fracture mechanics, Measurement, Alloys, Stress corrosion, Testing, Alloys, Corrosion fatigue, Testing
Format: Document (PDF)

Title: Rapid neuroprotection from acute oxidative stress.
Creator: Caplan, Stacee Lee, Dawson-Scully, Ken, Milton, Sarah L., Graduate College
Date Issued: 2011-04-08
PURL: http://purl.flvc.org/fcla/dt/3164512
Subject Headings: Stress --physiology, Protein kinases, Neuroprotective agents
Format: Document (PDF)

Title: The role of methionine sulfoxide reductase in thermal stress response.
Creator: Martin, James, Bruce, Lindsay, Schey, Karin, Binninger, David
Date Issued: 2013-04-05
PURL: http://purl.flvc.org/fcla/dt/3361149
Subject Headings: Hyperthermia, Heat shock proteins, Methionine, Oxidative stress
Format: Document (PDF)

Title: Alternative Biological Roles of Methionine Sulfoxide Reductases in Drosophila melanogaster.
Creator: Wilson, Kelsey, Binninger, David, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: The oxidation of methionine (Met) into methionine sulfoxide (met-(o)) leads to deleterious modifications to a variety of cellular constituents. These deleterious alterations can be reversed by enzymes known as methionine sulfoxide reductases (Msr). The Msr (MsrA and MsrB) family of enzymes have been studied extensively for their biological roles in reducing oxidized Met residues back into functional Met. A wide range of studies have focused on Msr both in vivo and in vitro using a variety of...
Show moreThe oxidation of methionine (Met) into methionine sulfoxide (met-(o)) leads to deleterious modifications to a variety of cellular constituents. These deleterious alterations can be reversed by enzymes known as methionine sulfoxide reductases (Msr). The Msr (MsrA and MsrB) family of enzymes have been studied extensively for their biological roles in reducing oxidized Met residues back into functional Met. A wide range of studies have focused on Msr both in vivo and in vitro using a variety of model organisms. More specifically, studies have noted numerous processes affected by the overexpression, under expression, and silencing of MsrA and MsrB. Collectively, the results of these studies have shown that Msr is involved in lifespan and the management of oxidative stress. More recent evidence is emerging that supports existing biological functions of Msr and theorizes the involvement of Msr in numerous biological pathways.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00005980
Subject Headings: Drosophila melanogaster, Methionine Sulfoxide Reductases, Oxidative stress
Format: Document (PDF)

Title: A Study on the Potential Role of Stress Granules and Processing Bodies in Eliminating Oxidatively Damaged RNA.
Creator: Pourkalbassi, Delaram, Li, Zhongwei, Florida Atlantic University, Charles E. Schmidt College of Medicine, Department of Biomedical Science
Abstract/Description: Oxidative stress (OS) is strongly implicated in age-related neurodegeneration and other diseases. Under OS, the production of excessive oxidants leads to increased damages to cellular components. Recently, RNA has been discovered as a major target of oxidative damage, including the creation of abasic sites. In this work, we developed a method for quantifying abasic RNA in cell. Using this method, we have examined the potential role of the RNA-processing cellular foci, stress granule (SG) and...
Show moreOxidative stress (OS) is strongly implicated in age-related neurodegeneration and other diseases. Under OS, the production of excessive oxidants leads to increased damages to cellular components. Recently, RNA has been discovered as a major target of oxidative damage, including the creation of abasic sites. In this work, we developed a method for quantifying abasic RNA in cell. Using this method, we have examined the potential role of the RNA-processing cellular foci, stress granule (SG) and processing bodies (PB) in eliminating abasic RNA in situ. We demonstrated that RNA is a major target of oxidative damage, constituting the majority of OS-induced abasic nucleic acids in HeLa cell. Importantly, the level of abasic RNA is strongly correlated with SG abundance. Furthermore, inhibition of SG/PB formation causes accumulation of abasic RNA, suggesting that SG/PB participates in removing oxidized RNA and protects cells under OS, which offers novel targets for therapeutic intervention in age-related diseases.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004702
Subject Headings: Aging -- Physiological aspects., Oxidative stress., RNA -- Metabolism.
Format: Document (PDF)

Title: Unraveling the molecular mechanism of human polynucleotide phosphorylase (hPNPase) in controlling oxidized RNA.
Creator: Malla, Sulochan, Li, Zhongwei, Florida Atlantic University, Department of Biomedical Science, Charles E. Schmidt College of Science
Abstract/Description: Oxidation by reactive oxygen species is the major source of RNA damaging insult in living organisms. Increased RNA oxidation has been strongly implicated in a wide range of human diseases; predominantly neurodegeneration. Oxidized RNA should be removed from the cellular system to prevent their deleterious effect to the cells and organisms. In eukaryotic cells, mitochondria are the major intracellular sources of ROS and may cause greater damage to the mitochondrial RNA. In this study, we first...
Show moreOxidation by reactive oxygen species is the major source of RNA damaging insult in living organisms. Increased RNA oxidation has been strongly implicated in a wide range of human diseases; predominantly neurodegeneration. Oxidized RNA should be removed from the cellular system to prevent their deleterious effect to the cells and organisms. In eukaryotic cells, mitochondria are the major intracellular sources of ROS and may cause greater damage to the mitochondrial RNA. In this study, we first investigated the RNA oxidation, by measuring the level of 8-hydroxy-Guanosine (8-oxo-Guo), inside mitochondria and cytoplasm in cultured human cells. We discovered that the mitochondrial 8-oxo-Guo is higher than its cytoplasmic counterparts under both normal growth and oxidative stress condition. Next, we explored the role of human polynucleotide phosphorylase (hPNPase) in controlling RNA oxidation inside mitochondria and cytoplasm. hPNPase binds to oxidized RNA with higher affinity, reduces the 8-oxo-Guo level in total RNA and protects cells against oxidative stress. In this study, the molecular mechanism of hPNPase in 8-oxo-Guo reduction was investigated. First, the effect of hPNPase activities on the 8-oxo-Guo level in mitochondria and cytoplasm was examined. The knockdown of hPNPase increased both the mitochondrial and cytoplasmic 8-oxo-Guo, whereas overexpression had the opposite effect. Second, our study revealed that hSUV3, an RNA helicase that forms a functional complex with hPNPase in mitochondria, was dispensable in reducing 8-oxo-Guo levels.
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Date Issued: 2019
PURL: http://purl.flvc.org/fau/fd/FA00013392
Subject Headings: RNA, Reactive Oxygen Species, Mitochondria, Oxidative stress
Format: Document (PDF)

Title: Role and Regulation of Methionine Sulfoxide Reductase (Msr) in a model of oxidative stress tolerance: Trachemys scripta.
Creator: Reiterer, Melissa, Milton, Sarah, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: The detrimental effects of oxidative stress caused by the accumulation of Reactive Oxygen Species (ROS) have been acknowledged as major factors in aging, senescence and several neurodegenerative diseases and conditions such as Parkinson’s disease and stroke (ischemia/reperfusion). Mammalian models are extremely susceptible to these stresses that follow the restoration of oxygen after anoxia; however, some organisms including the freshwater turtle Trachemys scripta can withstand several bouts...
Show moreThe detrimental effects of oxidative stress caused by the accumulation of Reactive Oxygen Species (ROS) have been acknowledged as major factors in aging, senescence and several neurodegenerative diseases and conditions such as Parkinson’s disease and stroke (ischemia/reperfusion). Mammalian models are extremely susceptible to these stresses that follow the restoration of oxygen after anoxia; however, some organisms including the freshwater turtle Trachemys scripta can withstand several bouts of anoxia and repeated reoxygenation without any apparent pathology. T. scripta thus provides us with an alternate vertebrate model in which we can investigate physiological mechanisms of neuroprotection without the damaging effects that come with oxidative stress. The major objective of this study was to investigate the protective mechanisms in the turtle brain under conditions of anoxia and oxidative stress. Specifically, the focus is on the Methionine Sulfoxide Reductase system (Msr), an antioxidant and cellular repair system, and how it is regulated to protect the brain against such stressors. Previous studies in my lab have demonstrated that Msr mRNA and protein levels are differentially upregulated during anoxia and reoxygenation. To investigate the regulation of Msr, FOXO3a was directly induced by transfecting a human FOXO3a plasmid into turtle brain cell cultures, as FOXO3a has been shown to regulate MsrA levels in other animal models. Pharmacological manipulation of FOXO3a was also performed using the green tea extract Epigallocatechin gallate (EGCG) as it has been shown to increase expression of FOXO3a during oxidative stress conditions in other models. I found that an induction of human FOXO3a increased FOXO3a levels and showed protection against cell death during oxidative stress. Furthermore, treatment of cells with EGCG increased expression of FOXO3a only when the cells were exposed to oxidative stress and decreased cell death. Induction of FOXO3a and EGCG treatment did not increase MsrA levels, however MsrB3 levels were upregulated under both treatments but only in the presence of oxidative stress. These results suggest that MsrA and MsrB3 protect the cells from oxidative stress damage through different molecular pathways and that EGCG may be a therapeutic target to treat diseases related to damage by oxidative stress.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013154
Subject Headings: Methionine Sulfoxide Reductases, Oxidative Stress, Trachemys scripta
Format: Document (PDF)

Title: Degradation of composite materials in a marine environment.
Creator: Pomies, Frederic., Florida Atlantic University, Carlsson, Leif A., College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: Degradation of composite materials in marine environments has been investigated experimentally and with analytical and numerical methods. Basic mechanical properties, fiber volume fraction, moisture absorption curves and transverse tensile properties after water absorption were determined. Transverse fracture surfaces of dry and wet composites were inspected in a scanning electron microscope (SEM). In addition, the edge replication technique was applied. Micromechanical stress analysis of a...
Show moreDegradation of composite materials in marine environments has been investigated experimentally and with analytical and numerical methods. Basic mechanical properties, fiber volume fraction, moisture absorption curves and transverse tensile properties after water absorption were determined. Transverse fracture surfaces of dry and wet composites were inspected in a scanning electron microscope (SEM). In addition, the edge replication technique was applied. Micromechanical stress analysis of a composite subjected to mechanical, thermal and moisture loading were performed using analytical methods and finite elements. Transverse stiffness and stress levels for interfacial debonding and matrix failure were calculated and correlated with transverse stiffness and strength obtained experimentally.
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Date Issued: 1992
PURL: http://purl.flvc.org/fcla/dt/14818
Subject Headings: Composite materials, Environmental monitoring, Stress corrosion
Format: Document (PDF)

Title: Weight function approach for stress analysis of the surface crack in a finite plate subjected to nonuniform stress fields.
Creator: Jani, Jayant Shivkumar., Florida Atlantic University, Arockiasamy, Madasamy, College of Engineering and Computer Science, Department of Ocean and Mechanical Engineering
Abstract/Description: The effects of various nonuniform stress fields on the stress intensity factors for the semi-elliptic surface crack (three-dimensional problem) in a finite plate are determined using the weight function approach. The formulation satisfies the linear elastic fracture mechanics criteria and the principle of conservation of energy. Based on the knowledge of stress intensity solutions for the reference load/stress system, the expression for the crack opening displacement function for the surface...
Show moreThe effects of various nonuniform stress fields on the stress intensity factors for the semi-elliptic surface crack (three-dimensional problem) in a finite plate are determined using the weight function approach. The formulation satisfies the linear elastic fracture mechanics criteria and the principle of conservation of energy. Based on the knowledge of stress intensity solutions for the reference load/stress system, the expression for the crack opening displacement function for the surface crack is derived. Using the crack opening displacement function and the reference stress intensity factor, the three-dimensional weight functions and subsequently the stress intensity solutions for the surface crack subjected to nonuniform stress fields are derived. The formulation is then applied to determine the effects of linear, quadratic, cubic, and pure bending stress fields on the stress intensity factor for the surface crack in a finite plate. In the initial stage of the study a two-dimensional problem of an edge-crack emanating from the weld-toe in a T-joint is considered. The effect of parameters such as plate thickness, weld-toe radius, and weld-flank angle on the stress intensity factor for an edge-crack is studied. Finite element analyses of the welded T-joints are performed to study the effects of plate thickness, weld-toe radius and the weld-flank angle on the local stress distribution. The ratio of plate thickness to weld-toe radius ranging from 13.09 to 153.93, and the weld-flank angles of 30, 45, and 60 degrees are considered in the analyses. Based on the results from FEM analyses, a parametric equation for the local stress concentration factor and a polynomial expression for the local stress distribution across the plate thickness are derived using the method of least squares and the polynomial curve-fitting technique.
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Date Issued: 1990
PURL: http://purl.flvc.org/fcla/dt/12254
Subject Headings: Strains and stresses, Plates (Engineering), Fracture mechanics
Format: Document (PDF)

Title: Commitment - the bridge to caring: The meaning of commitment as lived by critical-care nurses.
Creator: Cutler, Sharon Brown., Florida Atlantic University, Schoenhofer, Savina
Abstract/Description: The aim of this study was to understand the meaning of commitment to nursing from the perspective of critical-care nurses. Phenomenology was the research method. Van Manen's approach guided this study with Munhall's adaptation of existential investigation. Seven nurses participated. All were selected on a voluntary basis provided they were working in critical-care, had two years of critical-care experience, and were willing to talk about the topic of commitment. Several themes emerged as...
Show moreThe aim of this study was to understand the meaning of commitment to nursing from the perspective of critical-care nurses. Phenomenology was the research method. Van Manen's approach guided this study with Munhall's adaptation of existential investigation. Seven nurses participated. All were selected on a voluntary basis provided they were working in critical-care, had two years of critical-care experience, and were willing to talk about the topic of commitment. Several themes emerged as essential to humanistic experience of commitment to nursing. Contextual descriptions of commitment also emerged. The nurses' primary commitment was to the patient and the ethical dilemmas that surfaced when they tried to honor that commitment proved the major source of frustration and dissatisfaction. Commitment was found to be the connection or bridge to caring. Without commitment there was no caring. Implications for nursing administration and education were addressed. Additional questions were raised for future research.
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Date Issued: 1993
PURL: http://purl.flvc.org/fcla/dt/14965
Subject Headings: Intensive care nursing, Nurses--Job stress
Format: Document (PDF)

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