A B S T R A C T Presented work focuses on experimental study of anion interaction with neutral particles at temperatures relevant for astrophysics. Anion H− , important for molecular hydrogen creation, and O− as a possible source of water are investigated. The temperature dependence of reac- tion rate coefficients from 10 to 150 K for reactions H− + H → H2 + e− and O− + H2 → H2O + e− has been determined. The energy distri- bution of electrons produced in the latter reaction at 300 K has also been acquired. These studies have been performed on two experimen- tal setups, which are presented together with the theory of operation, construction details, calibration, and supporting test measurements.

Detergents are broadly used in our everyday life for cleaning and washing procedures. They are however, a source of water pollution and can have a negative effect on human health and the environment. To reduce their negative impact, a new trend of using only pure water for washing and cleaning applications is being implemented. However, a scientific basis needs to be established first, as the mechanisms and the effectiveness of this method are not fully understood. In this work, we aim to investigate the effect of water purity on the removal of oil from surfaces and the stability of colloidal systems. To do that, two purified water grades are compared with non-purified tap water and 10 mM NaCl solution. Results from measurement of oil film mass before and after water contact and Quartz Crystal Microbalance with Dissipation (QCM-D) indicate that purified water grades can wash a surface more efficiently than non-purified water grades. Contact angle measurements show that pure water facilitates the cleaning process while spreading of oil on plastic surfaces indicates that electrostatic interactions have an important role in the system. Visual observations of o/w emulsions, show that purified water grades redisperse the oil better. We hypothesize that the mechanism behind the cleaning and washing without detergents relies on the electrostatic interactions. To further investigate the effect of salt on cleaning mechanisms, we performed zeta potential measurements. Results indicate that salt has a negative effect on the stability of the particles.

Hot spring geochemistry from the Peruvian Andes provide insight on how faults, or fractures in the Earth's crust, are capable of influencing fluid circulation. Faults can either promote or inhibit fluid flow and the goal of this study is test the role of a major fault, such as the Cordillera Blanca detachment, as a channel for transporting deep fluids to the surface. Hot springs are abundant in the Cordillera Blanca and Huayhuash ranges in Peru, and several springs issue along the Cordillera Blanca detachment, making this region an ideal setting for our study. To test the role of the Cordillera Blanca detachment, hot springs were sampled along the trace of the fault (Group 1), the western edge of the Cordillera Blanca (Group 2), the eastern side of the Cordillera Blanca (Group 3), and in the Cordillera Huayhuash (Group 4). Water and dissolved gas samples were collected from a total of 25 springs and then analyzed for an array of geochemical parameters. Distinct fluid chemistries from Groups 1 and 2 suggest that the Cordillera Blanca detachment and adjacent minor faults to the west intersect at depth and provide a preferential flow path for deep fluid circulation. Understanding the influence of faults on fluid flow is essential for many disciplines (e.g. oil exploration, hydrology), and this work demonstrates that fluid geochemistry is an excellent tool for assessing the role of faults on fluid distribution.

No description available.

No description available.

Completing tasks and reaching goals at work depletes employees’ energy, motivation, and attentional resources, resulting in negative stress and fatigue experiences. Taking microbreaks from work may help recover from work demands and replenish these resources by positively affecting employee well-being and performance. Therefore, this study seeks to understand the potential benefits of personal social media use as a specific microbreak activity that has become increasingly popular in recent years for employee recovery and productivity during working hours. More specifically, the engagement in social media microbreaks (SMMB) was hypothesized to positively predict both employees’ psychological detachment and perceived productivity. Cross-sectional survey data from 193 white-collar workers were collected and analyzed using linear regression. The results of this correlational study revealed that while engagement in SMMB activities positively predicted psychological detachment, perceived productivity was not found to be associated with SMMBs when holding employees’ general engagement in social media and socially desirable responding constant. Exploratory analyses showed that these relationships may be contingent on demographic, individual, and work (break) characteristics. These findings challenge the predominant negative connotation of using social media at work among employers and by contributing to a growing body of evidence suggesting the restorative nature of microbreaks. Yet, this research underlines the necessity for further research to elucidate the boundary conditions for effective (social media) microbreaks.

Quinolones are a group of antibiotics that have gained significant popularity on a global scale since the end of the last century. This popularity was predominantly based on their proven potency, broad coverage against a wide range of bacteria, in addition to possessing a favorable pharmacologic profile. Whereas quinolone-associated adverse reactions are generally tolerable and self-limiting, some reactions have generated heightened concerns due to their serious nature, which have resulted in label changes or even market withdrawal in some instances. This thesis investigates the association between quinolone antibiotics and two adverse reactions of an acute and serious nature: acute liver failure and retinal detachment. Each adverse reaction is investigated through integrating evidence from three studies utilizing different designs based on data from different sources, with each source offering a unique perspective on this issue. The first study type (chapter 2 for acute liver failure ‘ALF’ and Chapter 5 for retinal detachment ‘RD’) analyzes spontaneous reports submitted to the US Food & Drug Administration (FDA) adverse event reporting system database. Chapters 3 and 6 systematically identified all relevant (published and unpublished) clinical trials for occurrences of ALF and RD, respectively, among trial participants. Finally, chapters 4 (ALF) and 7 (RD) involved case-control analysis of a major US database of electronic health records for nearly 70 million inpatients admitted to more than 500 hospitals between 2000 and 2016. The FAERS analysis revealed a positive ALF signal with ciprofloxacin and a marginal signal for RD with moxifloxacin. Examination of the evidence from clinical trials revealed only two cases of ALF, one associated with gemifloxacin and one with moxifloxacin. No cases of RD were reported in any of the identified clinical trials. Primary analyses of the Health Facts® data revealed no overall association between quinolones and the risk of ALF or RD. However, elevated risk was identified in some subgroups, including African Americans (ALF, RD), Caucasians (ALF), women (ALF, RD), men (ALF), those ≤60 years of age (ALF) or 56-70 years of age (RD), and those with no or few comorbidities (ALF). Evidence from analyses of data from spontaneous reports and clinical trials provided some evidence for an elevated risk of ALF or RD following the systemic administration of quinolone antibiotics. Some evidence of elevated risk was also identified in the case-control analyses of inpatient EHR records. Findings from our six epidemiologic studies are in line with current advisories by FDA and Health Canada.

No description available.

<p>In an effort to better understand the physical mechanisms responsible for pool boiling heat transfer, an analytical model is developed that better describes the changing shape and size of a growing bubble. Indeed, any analysis of thermal transport due to nucleate pool boiling requires bubble frequency predictions which are intimately linked to bubble volume. The model is developed and validated for quasi-static bubble growth due to gas injection and for bubble growth due to vaporization within the heat-transfer controlled growth regime; it highlights the need to include the asymmetric nature of growing bubbles when modeling bubble growth.</p> <p>In addition, a numerical study of quasi-static bubble shape for both adiabatic bubble growth and vapour bubble growth provides insight into the dependence the bubble shape evolution has on the Bond number. In so doing, bubble profiles generated from a numerical treatment of the Capillary equation are benchmarked to quasi-static gas injected bubble formations and to heat-transfer controlled vapour bubble formations.</p> <p>The numerical treatment of bubble shape evolution leads to a simplifying bubble geometry for low Bond number applications. The geometric model accounts for bubble shape transformation throughout the bubble growth cycle including the necking phenomenon. An analytical model of quasi-static adiabatic bubble growth is accordingly developed based on the proposed low Bond number geometric model; it is coupled with a geometric detachment relation and a force balance detachment criterion that are dependent on the Bond number. The resulting predicted bubble growth characteristics, such as profile, volume, centre of gravity and aspect ratio, are validated with the benchmarked numerical treatment of the problem.</p> <p>Furthermore, the low Bond number geometric model is applied to bubble growth due to vaporization. In order to solve the mass-energy balance at the vapour bubble interface, a spherical surface area is commonly assumed. This leads to the need for correction factors and provides little insight into the physical mechanism responsible for bubble shape. In this study, the transitioning shape of a vapour bubble is considered in the integral analysis of the interfacial mass-energy balance. The model predicts the following bubble growth characteristics: profile, volume, centre of gravity, and aspect ratio.</p> / Doctor of Philosophy (PhD)

A flotation model has been proposed that is applicable in a turbulent environment. It is the first turbulent model that takes into account hydrodynamics of the flotation cell as well as all relevant surface forces (van der Waals, electrostatic, and hydrophobic) by use of the Extended DLVO theory. The model includes probabilities for attachment, detachment, and froth recovery as well as a collision frequency. A review of the effects fluids have on the flotation process has also been given. This includes collision frequencies, attachment and detachment energies, and how the energies of the turbulent system relate to them. Flotation experiments have been conducted to verify this model. Model predictions were comparable to experimental results with similar trends. Simulations were also run that show trends and values seen in industrial flotation systems. These simulations show the many uses of the model and how it can benefit the industries that use flotation. / Ph. D.