Mechanics of Fracture in Adhesive Joints

Interdependence of continuum mechanics and physical chemistry in failure analysis of adhesive

Marital Roles and Their Relationship to Marital Happiness and Self Concept

Marital roles have become a subject of major concern in recent years. Many critiques consider traditional marriage roles to be responsible for hindering appropriate social-emotional development of the wife, in particular, and also the husband. Past research in assessing the relationship between marital roles and the happiness and well-being of husbands and wives is limited in quantity and generally is inconclusive or controversial. This study was designed to clarify the relationship between marriage roles and two dependent variables, marital happiness and self concept. The sample population consisted of 124 volunteer couples selected from the teaching staffs of eight school districts in Southeastern Idaho and Northern Utah. Each participant provided information for this study by completing a questionnaire, the Tennessee Self Concept Scale, the Marriage Adjustment Scale, and the Marriage Role Expectation Inventory. Forty-three variables were generated from these measures which, when factor analyzed produced 12 factors for husbands and 10 factors for wives, served as dependent and independent variables for this study. Stepwise multiple regression analysis was used to identify relationships between dependent variables (self concept and marital happiness of husbands and wives) and independent variables {i.e., level of education; hours spent as an employee, religious volunteer, and in community service; freedom to choose present role; income level). Husbands and wives were assessed independent of each other. None of the independent variables explained a significant amount of the variance on marital happiness or self concept neither when considered alone nor when stepped together in the multiple regression model. Thus, no significant relationship was determined between marital roles and marital happiness or self concept. Recommendations were made for studying more diversified populations and for controlling sample bias resulting from the use of volunteers

Methods for identifying frost injury in immature maize seed

Fall frost damage is a major threat to maize (Zea mays L.) seed production in the central United States. Frost events prior to harvest can cause various physical, mechanical, biochemical, and physiological changes to immature seed corn. These changes can lead to decreased germination and vigor. Early detection of frost damage could reduce the financial loss caused by poor emergence when these seed lots are planted. The central hypotheses of this dissertation are that the severity of a frost event can be quantified shortly after seed has been harvested and dried, and that the magnitude of the damage is associated with seed development and genetic background of the seed. This information can be used to predict field emergence of frosted seed lots. Many different aspects of frost damage have been explored in this project, which provides several methods for identifying frost damage in maize seed. This project advances our understanding of seed physiology as related to frost damage and changes in physiology during seed maturation. Chapter 2 is a practical application of the tetrazolium test for identifying frost damage in seed corn and relating these results to vigor. Chapter 3 discusses the influence of female parent and moisture content at harvest in frost tolerance or injury. Chapter 3 also provides a detailed analysis of seed quality tests and their usefulness in predicting field emergence of frost damaged seed. Chapter 4 establishes the use of RNA extraction and qRT-PCR as a valid method for evaluating gene expression in dry maize seed

Beyond the Obvious: Emerging Contaminants and Biogeochemistry as a Cause and Solution for Nitrogen Pollution

Following a comprehensive review of the occurrence and impacts of antibiotics and related pharmaceutical compounds on the terrestrial N-cycle, three experiments were performed to explore the topic of biogeochemistry as a source or a sink for N-pollution. The first of these experiments addresses the question of whether environmentally relevant concentrations of antibiotics (µg·kg-1) have a significant effect on denitrification or N2O production, a question that has not been well addressed in previous studies. Having determined that there is a significant shift, the second study aims to comprehensively follow changes to soil N pools and N2O flux alongside biogeochemical reaction rates under different soil moisture conditions. The final chapter of this research, Chapter 5, looks to biogeochemistry as a solution for some of the water quality issues associated with excess N by quantifying the rate at which sand columns inoculated with lake sediment biodegrade undesirable taste/odor compounds and toxins produced by cyanobacterial algae that proliferate in nitrogen-rich waters. The results of this work show that the balance between soil as a source or a sink of N pollutants can be significantly disturbed by sources beyond the obvious, i.e. antibiotics. It further shows that biogeochemical activity can serve as an effective treatment for secondary N-pollution. Additional research is encouraged to test the effects of additional antibiotics and by extending the incubation period to longer time periods. In particular, there also exists a need to examine the short and long-term effects of antibiotics on soil microbial community structure. While the present work shows that endemic bacteria can degrade nuisance compounds in N-polluted waters, the efficacy of this activity may also be affected by long-term antibiotic exposure in sediment. Genetic tools including GeoChip, will help to better constrain changes that are relevant to all aspects of these findings

Acute neuroinflammation induces AIS structural plasticity in a NOX2-dependent manner

Background Chronic microglia-mediated inflammation and oxidative stress are well-characterized underlying factors in neurodegenerative disease, whereby reactive inflammatory microglia enhance ROS production and impact neuronal integrity. Recently, it has been shown that during chronic inflammation, neuronal integrity is compromised through targeted disruption of the axon initial segment (AIS), the axonal domain critical for action potential initiation. AIS disruption was associated with contact by reactive inflammatory microglia which wrap around the AIS, increasing association with disease progression. While it is clear that chronic microglial inflammation and enhanced ROS production impact neuronal integrity, little is known about how acute microglial inflammation influences AIS stability. Here, we demonstrate that acute neuroinflammation induces AIS structural plasticity in a ROS-mediated and calpain-dependent manner. Methods C57BL/6J and NOX2−/− mice were given a single injection of lipopolysaccharide (LPS; 5 mg/kg) or vehicle (0.9% saline, 10 mL/kg) and analyzed at 6 h–2 weeks post-injection. Anti-inflammatory Didox (250 mg/kg) or vehicle (0.9% saline, 10 mL/kg) was administered beginning 24 h post-LPS injection and continued for 5 days; animals were analyzed 1 week post-injection. Microglial inflammation was assessed using immunohistochemistry (IHC) and RT-qPCR, and AIS integrity was quantitatively analyzed using ankyrinG immunolabeling. Data were statistically compared by one-way or two-way ANOVA where mean differences were significant as assessed using Tukey’s post hoc analysis. Results LPS-induced neuroinflammation, characterized by enhanced microglial inflammation and increased expression of ROS-producing enzymes, altered AIS protein clustering. Importantly, inflammation-induced AIS changes were reversed following resolution of microglial inflammation. Modulation of the inflammatory response using anti-inflammatory Didox, even after significant AIS disruption occurred, increased the rate of AIS recovery. qPCR and IHC analysis revealed that expression of microglial NOX2, a ROS-producing enzyme, was significantly increased correlating with AIS disruption. Furthermore, ablation of NOX2 prevented inflammation-induced AIS plasticity, suggesting that ROS drive AIS structural plasticity. Conclusions In the presence of acute microglial inflammation, the AIS undergoes an adaptive change that is capable of spontaneous recovery. Moreover, recovery can be therapeutically accelerated. Together, these findings underscore the dynamic capabilities of this domain in the presence of a pathological insult and provide evidence that the AIS is a viable therapeutic target

The effect of vacuum polarisation on muon-proton scattering at small energies and angles

We give a compact expression for the unpolarised differential cross section for muon-proton scattering in the one photon exchange approximation. The effect of adding the vacuum polarisation amplitude to the no-spin-flip amplitude for one photon exchange is calculated at small energies and scattering angles and is found to be negligible for present experiments.Comment: 6 pages, one figur

Fracture Mechanics of Joints

Almost every engineering design requires that component members be connected. A disadvantage of mechanical connections such as bolts, screws or rivets is that they do not uniformly distribute the load; hence large local stresses result. This problem can often be reduced ~ joining the members adhesively. Major problems with adhesives that have tended to limit their wider us age include: (1) how the strength of an adhesive and the joint in which it is used can reliably be predicted, and (2) what factors tend to limit the strength of an adhesive joint and how they might be eliminated . It is the intent of the authors to show how fracture mechanics might be used to develop a rational philosophy and methodology that will aid in overcoming these problems