The purpose of this thesis was to determine the kinetics and stoichiometry for the aquation of the pentaaquomonobromonmethylchromium(III) complex. The complex was prepared by the reduction of dibromomethane by chromium(II). The products of aquation, in the absence of oxygen, were found to be hexaaquachromium(III), methanol, and bromide. The balanced net ionic reaction can be written: 2H2O + (H2O)5CrCH2Br2+ → (H2O)6Cr3+ + CH3OH + Br-

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Candidate: Kateřina Klimková Supervisor: Assoc. Prof. Přemysl Mladěnka, Pharm. D., Ph.D. Consultant: Assoc. Prof. Kateřina Valentová, Ph.D. Title of Thesis: Determination of the stoichiometry of the copper complexes with dehydrosilybin A Silymarin, the standardized extract of the milk thistle (Silybum marianum), is a widely used approved over-the-counter drug that is recommended for a number of liver diseases. Silymarin contains as one of its components 2,3-dehydrosilybinA, which has an appropriate metal binding site in its structure. In general, flavonolignans, due to their structure, can interact with transition metals in the gastrointestinal tract by forming complexes. This property can be useful for the protection against excessive amounts of metals in the body. The aim of this in vitro study was to analyse the interaction of 2,3-dehydrosilybin A with copper, which plays a crucial role in the organism as a cofactor of many enzymes. Although being an essential element, it can, however, be toxic at elevated levels. Stoichiometry, as one of the most important characteristics of the complex, was determined by UV-Vis spectrophotometry in four (patho)physiological pH conditions (4.5; 5.5; 6.8; 7.5)...

This thesis attempts to test the effects of barium non stoichiometry and varying calcination temperatures on the microstructure and electrical conductivity of BaxZr0.7Pr0.1Y0.2O3- δ (x = 0.9, 1.0, 1.1). BZPY powders were fabricated using a combustion method, with the quantity of barium carefully controlled to create powders with a 10% molar excess or deficiency of barium. Then, portions of the precursor were calcined at 900 ºC, 1000 ºC, 1100 ºC, 1200 ºC and 1300 ºC for 5 h. The resulting calcined powders were pressed into pellets and sintered at 1600 ºC for 10 h, in a powder bath of the same chemical composition. In all, three chemically different powders were synthesized, and each composition was subjected to five different calcination temperatures, resulting in fifteen different samples to characterise. The precursor from the combustion method was characterised by using an STA to perform both TG and DSC simultaneously. The chemical composition of the precursor and calcined samples was analysed using ICP-OES. XRD was used to characterise the phases of both the powders and the sintered pellets. Lattice parameter indexing using Topaz and Scherrer's equation were used to extract the lattice parameters and crystallite sizes respectively. The microstructure of the pellets was examined using an SEM, the grain size measured using a linear intercept method and pore size using ImageJ. Finally, EIS was used to measure the conductivity of the pellets in dry and wet Argon atmospheres, with silver electrodes. Unfortunately, neither changes to barium stoichiometry nor partial calcination could improve the performance of BZPY. Partially calcined samples did not give rise to dense pellets, barium deficient samples showed inferior conductivity and barium excess samples, while showing higher conductivity than the barium deficient pellets at high temperature, were fragile and had to be handled carefully. Ultimately, the attempt to improve the performance of BZPY did not succeed and alternate methods of improving the grain growth need to be sought.

The feasibility of using an integrated rate equation to analyze the kinetics of a second-order, enzyme-catalyzed reaction has been investigated. The inducible arginine decarboxylase from Escherichia coli B. was chosen for this study because it catalyzes an irreversible reaction with stoichiometry A --> P + Q, the simplest second order case. Values for five of the eight possible kinetic constants were determined from 21 time courses. Of the remaining three, the uncompetitive product inhibition constant for CO2 was shown to be between O and 0.06, while the values of the competitive product inhibition for CO2 and the uncompetitive constant for arginine, agmatine and CO2 simultaneously do not appear to be appreciably different from zero. Initial rate analysis of the time courses gave similar results. The results obtained by varying the initial agmatine concentration at a low initial arginine concentration were not consistent with the rest of the data. This appears to be due to a. fundamental difference in the behavior of the enzyme under those conditions rather than to a problem associated with the analysis.

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第21647号 / 医博第4453号 / 新制||医||1034(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 高橋 淳, 教授 藤渕 航, 教授 岩田 想 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

A thesis submitted to the Faculty of Science, University of the Witwatersrand In partial fulfillment of the requirements for the degree of Master of Science (Science Education) Johannesburg, 2017 / Over the past three years, National Senior Certificate diagnostic reports reported that learner performance in key chemistry topics remains an aspect for concern. In these reports, poor understanding of stoichiometry is identified as an underlying factor. On the other hand, the status of mathematics and science teaching has been under critique by several education researchers, pointing to poor teacher training in the subjects. One possible way to respond to the challenge in science education is to introduce and emphasize the development of Topic Specific Pedagogical Content Knowledge (TSPCK) as the professional knowledge for teaching science topics in Initial Teacher Education (ITE) programme. TSPCK is renowned for enabling teachers to pedagogically transform difficult content of specific science topics into forms best understandable by learners. This study examined the impact on the quality of TSPCK following an intervention that explicitly targeted the development of the competence to transform content knowledge using stoichiometry as a topic of learning. This examination happened as teacher plan to teach the topic. The study followed a Mixed Method research design and a case study as a research strategy. It was located in the methodology class of physical science IV. The participants were 10 pre-service teachers who were in their final year of Bachelor study in education (B. Ed). They were bound by the requirements of the course and their common choice of physical science as their major subject. These pre-service teachers were exposed to a TSPCK based intervention that explicitly targeted the development of TSPCK component interaction. More evidence of component interactions was comprehended as developing quality of TSPCK. Quantitative data was collected as a set of pre- and post-intervention TSPCK tests using existing, specially designed tools that were developed and validated in a separate study. Five (5) of the then pre-service were followed a year later after the intervention to measure the quality of TSPCK in the topic of intervention in order to determine the extent of retention of the quality of TSPCK since the intervention. Qualitative data was collected through face to face interviews to confirm observed patterns of retention. The findings in this study indicated that pre-service teachers experienced a visible improvement in the quality of their TSPCK in stoichiometry as a direct result of the intervention. Pre-service teachers showed more evidence of component interactions post the intervention. The results further indicated that pre-service teachers experienced the components of TSPCK to have different levels of difficulty when using them to transform the content in stoichiometry during planning. The component of ―conceptual teaching strategies‖ was found to be the most difficult. A year later, the quality of TSPCK in planning to teach the topic of the intervention was found to have been retained by the then pre-service teachers. Recommendations about the implementation of TSPCK in core topics in ITE are made. Firstly, for initial teacher education, it is recommended that courses such as methodology for teaching chemistry be structured as TSPCK based intervention. Secondly, more work need to be done in the examination of retention span of TSPCK. Thus, similar studies must be conducted in an effort to increase empirical evidence about the extent at which TSPCK is retained by beginning teachers. / MT 2017

Environmental stressors are ubiquitous. Animals will face a variety of natural and anthropogenic stressors throughout their life cycle. The physiological mechanisms that mediate stressful stimuli can have pleiotropic effects on life history traits, such as reproduction and development. Furthermore, these phenotypic changes can affect larger-scale ecosystem dynamics, like nutrient cycling and disease epizootics. Animals are not equally susceptible to stressors across all stages of their life cycles. Critical windows of development, common in young and developing animals, are time periods when stressors have an outsized effect and can permanently alter phenotype. Larval amphibians use a critical window in late larval development wherein activation of the hypothalamic-pituitary-adrenal/interrenal (HPA/I) axis speeds their development, allowing them to metamorphose and escape suboptimal aquatic habitat. Accelerated development comes at a cost, the glucocorticoid (GC) hormones secreted by the HPA/I axis affect other systems such as growth, immune function, metabolism, and nutrient use. In chapter two, I investigated the effects of GC hormones on metabolism, energetics, and nutrient oxidation in larval wood frogs. The results show that GC hormones increase metabolism, reduce lipid stores, and increase protein oxidation during metamorphic climax. Chapter three focuses on the effects of GC hormones on immune function and r susceptibility. I found that chronic exposure to GC hormones increased ranavirus replication in infected wood frog larvae, but did not affect survival time. This could contribute to ranavirus epizootics. Acute GC hormone exposure increased survival, possibly by activing the inflammatory response. Finally, chapter four investigates the effects of GC hormones on nutrient stoichiometry. I found that larvae treated with GC hormones had lower nitrogen to phosphorus ratios, possibly because disrupted skeletal ossification. They also had reduced phosphorus excretion, which could affect ecosystem-level processes like nutrient cycling and decomposition.

Aquatic habitats are closely linked to surrounding terrestrial environments via reciprocal subsidies. Much of the research on these subsidies has been focused on streams, while subsidies across aquatic-terrestrial boundaries of other aquatic systems, like temporary ponds, have received little attention. Temporary ponds are seasonally inundated aquatic habitats and patterns of energy transport across transient aquatic-terrestrial boundaries are not well understood. To address the lack of information regarding these cross-habitat subsidies, I quantified: 1) leaf litter inputs, 2) amphibian egg inputs, 3) terrestrial insect inputs, 4) amphibian metamorph emergence, and 5) aquatic insect emergence for eight temporary ponds. Terrestrial insect inputs to ponds represented substantial high-quality subsidies to ponds that are generally unaccounted for in similar studies. While larger ponds produced greater total fluxes to terrestrial habitats, smaller ponds were often more productive per unit area. Therefore, a mosaic of small ponds may produce greater or equivalent subsidies and may be of greater value to terrestrial food webs than a single large pond. Resource subsidies of energy and nutrients can be transported via physical forces or biotic processes, such as animal migration or emigration. I quantified net nutrient fluxes associated with amphibian migrations across aquatic-terrestrial boundaries of eight temporary ponds in Illinois. I measured carbon (C), nitrogen (N), and phosphorus (P) subsidies from forests to ponds, in the form of eggs, and the reciprocal subsidies from ponds to forests via juvenile emigration. Juvenile emergence biomass did not resemble egg biomass, as not all species bred successfully in each pond, resulting in variability in the magnitude of nutrient fluxes both across ponds and species. The forest was not always the recipient system of net nutrient fluxes. Hydroperiod, trophic interactions, and species composition explained some dynamics of N and P subsidies. Most studies have focused on the magnitude of cross-boundary fluxes, but the impact of a subsidy is mediated by the size of the flux as well as the quality and relative abundance of similar resources in the recipient habitat. Long-chain polyunsaturated fatty acids (LC-PUFAs) are necessary for proper physiological function, are unevenly distributed across the landscape, and animals differ greatly in their ability to synthesize them de novo. This creates the potential for limitation and increases their possible importance as a subsidy. I examined LC-PUFA tissue concentration and export in eight species of emerging amphibian metamorphs across eight temporary ponds in a wetland complex. I found that tissue concentrations and export of LC-PUFAs varied across species, but were generally within the ranges of several freshwater fish and aquatic insects. Anurans exported higher amounts of LC-PUFAs than salamanders, largely due to the higher emergence biomass of anurans. Further, I explored fatty acid profiles and immune function of wolf spiders in wetland and upland habitats. Wetland spiders had higher tissue levels of aquatic-derived LC-PUFAs and elevated immune function compared to upland spiders. These patterns suggest aquatically derived nutrients, such as LC-PUFAs, may benefit organisms exploiting freshwater habitats.

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