Thesis (Ph.D.)--University of Nebraska-Lincoln, 2007. / Title from title screen (site viewed July 9, 2007). PDF text:180 p. : ill. (some col.) UMI publication number: AAT 3250075. Includes bibliographical references. Also available in microfilm and microfiche formats.

Thesis (M.Sc.)--York University, 2005. Graduate Programme in Mathematics and Statistics. / Typescript. Includes bibliographical references (leaves 61-62). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL: http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss &rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:MR11874

[From Introduction]. This thesis deals with the determination of copper and nickel both separately and in each other's presence. The work is divided into two sections, one of which treats the subject from the theoretical side while the other contains an account of the practical work performed by the author. In the theoretical section, an attempt is made to summarise the better-known methods for the determination of copper and nickel, and at the same time, to incorporate such improvements, criticism and variations as have appeared in the literature. The subject is so vast that its summary in so short a space must necessarily be incomplete. Yoe and Server, for example, quote 111 references on the subject of the nickel-dimethylglyoxine with other ions. Only a fraction of the literature was available, and space permitted only a fraction of this to be abstracted in the following pages.

In this thesis mass spectral and chromatographic techniques were developed and applied to identify and characterise numerous novel platinum(II) and (IV) compounds designed as anticancer agents. In a novel method for the synthesis of cis-oxalato(trans- -1,2- cyclohexanediamine)platinum(II) or oxaliplatin these techniques could be applied to differentiate between the molecular complex and the autoionised analogue (viz. Ptdach2 2+Ptox2 2-). In another novel synthetic method for the same compound the ligand exchange reactions at various temperatures could be investigated and kinetic curves obtained served to illuminate the chemistry involved, indicating the role of small amounts of water in the essentially non-aqueous solvent systems dmf and isoamyl alcohol respectively. These allowed ligand exchange without resulting in hydrolyses even up to 85°C. The ionisation rate of divalent platinum halide complexes was determined for various amine ligands as well as N-S chelate ligands. A comparison of these could suggest why N-S complexes have poor anticancer action. Ionisation was not only studied for neutral molecular species but also for monocationic ones. Relationships could be found with stereochemical aspects of the chelates used. By investigating results of EV-CAD studies thermodynamic data could be obtained which indicated that bond strength decreases from chloro to iodo analogues although extent of ionisation in aqueous solution, i.e kinetic stability, is the reverse. Products formed by the reaction of NO2 gas with Platinum(II) compounds could be identified and separated which greatly contributed to the understanding of the chemistry involved in the formation of mononitro platinum(IV) complexes. Some of these proved to have exceptional anticancer properties. Studies of the interaction of thiol containing biomolecules were performed as a function of time. The results contributed to the understanding of the action of the anticancer agents.

Studies in the general field of gas chromatographic analysis have been made and some of the methods developed have been applied to a kinetic investigation of the reactions of methyl radicals with butene-1. In Part I the developments in the field of gas chromatography are described. An all-metal thermal conductivity cell with platinum sensing elements has been designed and constructed. Excellent compensation for the resulting changes of flow rate of the carrier gas was attained in analyses with rising column temperature. The use of thermistors as sensing elements in such cells was also studied. The influence of polarity of the stationary phase on relative retention volumes in gas partition chromatography was investigated in conjunction with the analysis of a complex mixture of organic sulfur compounds. Satisfactory separations of hydrogen sulfide, methyl mercaptan, ethyl mercaptan, methyl sulfide, propyl mercaptan, ethyl sulfide, thiophene and dimethyl disulfide were obtained. Isopentane and n-pentane were included for purposes of comparison. Irregularities were observed in relating retention volumes to boiling points for some of these compounds. Reversal of normal elution order within groups of compounds with different columns was related to the polarity of the column and the polarisability of the eluents. A high-sensitivity ionization gauge detector for gas chromatography was developed. By keeping the grid potential below the ionization potential of helium the device is sensitive only to the eluted compounds in the gas stream. Sensitivities from 100 to 500 times greater than those of thermal conductivity cells were observed. Only a small fraction of the gas stream emerging from the column is sufficient for detection purposes, and the device is insensitive to temperature and flow rate changes. Significant advantages may be obtained from the application of the newly developed ionization gauge detector to displacement chromatography because of the possibility of distinguishing between isomeric organic compounds. Results obtained with gas chromatographic methods without the use of a carrier gas are reported. A partial separation of a mixture of volatile organic compounds was obtained. The ionization gauge detector may be useful in the development of this method. In Part II the results obtained from the reaction of methyl radical with butene-1 are described. Alumina, squalane-pelletex, and tricresyl phosphate columns were used for the gas chromatographic analysis. Mass spectrometric identification of products was done where necessary. In the temperature range 160 to 220°C with di-t-butyl peroxide as the methyl source the following reaction products were identified: methane, ethane, 3-methyl-butene-1, pentene-2, n-pentane, isopentane, 3-methyl-pentane, and acetone. A mechanism accounting for the formation of these products and supported by kinetic evidence is presented. The butenyl and pentyl radicals formed in the reaction are stable near 200°C. Butenyl radical does not abstract hydrogen from butene-1 near 200°C, but combines with methyl to yield pentene-2 and 3-methyl-butene-1. The energy of activation for the formation of 3-methyl-butene-1 is from 2 to 4 kcal/mole higher than for the formation of pentene-2. Hydrogen abstraction by pentyl radicals from butene-1 gives n-pentane, and isopentane. The reactivity of the branched radical •CH₂CH[CH₃]CH₂CH₃ in hydrogen abstraction is twice as great as that of the straight chain radical CH₃CH₂CHCH₂CH₃. From material balances obtained it was found that 60 to 80% of butenyl, and from 7 to 30% of pentyl radicals are removed from the system by reactions other than combination with methyl and hydrogen abstraction in the case of pentyl. The disproportionation of pentyl radicals to pentane and pentene was unimportant in the present system. At 450 and 492°C methyl radicals do not sensitize the formation of the cyclic reaction products which were observed by other workers in the unsensitized pyrolysis of butene-1 at temperature near 500°C. The main reaction product of methyl with butene-1 at 450 and 492°C was found to be butene-2. The isomerization to butene-2 in the unsensitized reaction is a chain process with chain length increasing with temperature reduction. The mechanism of the chain reaction of isomerization is postulated to be: CH₂=CHCH₂CH₃ → CH₃ • + CH₂ = CHCH₂ • / CH₃ • + CH₂=CHCH₂CH₃ → CH₂=CHCHCH₃ + CH₄ / CH₂=CHCHCH₃ ↔ •CH₂CH=CHCH₃ / •CH₂CH=CHCH₃ + CH₂=CHCH₂CH₃ → CH₃CH=CHCH₃+ CH₂=CHCHCH₃. The chain length at 450°C was found to be 12.6, and at 492°C as 2.3. / Science, Faculty of / Chemistry, Department of / Graduate

A survey of some chemical constituents of the lycopods was carried out in order to determine whether the chemistry of these plants is correlated with their taxonomy. One approach to this problem was to study the products of photosynthesis of species of Lycopodium. Selaginella and Isoetes. Radioactive C¹⁴O₂ was to fed these plants and the distribution of radioactivity in sugars and amino acids was examined by means of paper chromatography. The distribution of radioactivity in sugars was characteristic for each genus, but the distribution of radioactivity in amino acids was not. In Selaginella 80% or more of the radioactivity was incorporated into trehalose while most of the rest of the radioactivity was found in sucrose. There was one exception to this: in S. kraussiana 40% of radioactivity was incorporated into trehalose while most of the rest was incorporated into an unidentified sugar. In Isoetes 4% to 8% of the radioactivity was found in trehalose with most of the rest in sucrose. In Lycopodiurn 95% or more of the radioactivity was found in sucrose and none was found in trehalose. Radioactive trehalose was administered to species of these genera and it was shown that they are all able to metabolize trehalose to some degree. Species of Selaginella, Isoetes and Phylloglossum were examined to determine whether they contain alkaloids. Phylloglossum extracts contained compounds with the chromatographic properties of Lycopodiurn alkaloids, but Selaginella and Isoetes species did not contain detectable amounts of these compounds. / Science, Faculty of / Botany, Department of / Graduate

This thesis aims to develop some new and novel methods in advancing multivariate testing and multiple testing for high-dimensional small sample size data. In Chapter 2, we propose a likelihood ratio test framework for testing normal mean vectors in high-dimensional data under two common scenarios: the one-sample test and the two-sample test with equal covariance matrices. We derive the test statistics under the assumption that the covariance matrices follow a diagonal matrix structure. In comparison with the diagonal Hotelling's tests, our proposed test statistics display some interesting characteristics. In particular, they are a summation of the log-transformed squared t-statistics rather than a direct summation of those components. More importantly, to derive the asymptotic normality of our test statistics under the null and local alternative hypotheses, we do not need the requirement that the covariance matrices follow a diagonal matrix structure. As a consequence, our proposed test methods are very flexible and readily applicable in practice. Monte Carlo simulations and a real data analysis are also carried out to demonstrate the advantages of the proposed methods. In Chapter 3, we propose a pairwise Hotelling's method for testing high-dimensional mean vectors. The new test statistics make a compromise on whether using all the correlations or completely abandoning them. To achieve the goal, we perform a screening procedure, pick up the paired covariates with strong correlations, and construct a classical Hotelling's statistic for each pair. While for the individual covariates without strong correlations with others, we apply squared t statistics to account for their respective contributions to the multivariate testing problem. As a consequence, our proposed test statistics involve a combination of the collected pairwise Hotelling's test statistics and squared t statistics. The asymptotic normality of our test statistics under the null and local alternative hypotheses are also derived under some regularity conditions. Numerical studies and two real data examples demonstrate the efficacy of our pairwise Hotelling's test. In Chapter 4, we propose a regularized t distribution and also explore its applications in multiple testing. The motivation of this topic dates back to microarray studies, where the expression levels of thousands of genes are measured simultaneously by the microarray technology. To identify genes that are differentially expressed between two or more groups, one needs to conduct hypothesis test for each gene. However, as microarray experiments are often with a small number of replicates, Student's t-tests using the sample means and standard deviations may suffer a low power for detecting differentially expressed genes. To overcome this problem, we first propose a regularized t distribution and derive its statistical properties including the probability density function and the moments. The noncentral regularized t distribution is also introduced for the power analysis. To demonstrate the usefulness of the proposed test, we apply the regularized t distribution to the gene expression detection problem. Simulation studies and two real data examples show that the regularized t-test outperforms the existing tests including Student's t-test and the Bayesian t-test in a wide range of settings, in particular when the sample size is small.

<p>A model of the chemostat involving two populations of microorganisms competing for two perfectly substitutable resources is developed and analyzed. A general class of functions is used to describe nutrient uptake, one which allows for the effect that the concentration of each resource has on the amount of the other resource consumed. The model significantly generalizes those previously studied. The dynamics of this model are then compared with the dynamics of the classical growth and two-species competition models, as well as models involving two perfectly complementary resources.</p> <p>It is not surprising that the above competition for two resources can result in the coexistence of the two competitor populations. However, an example is also given in which the extinction of one population is averted by the introduction of its competitor. Thus, exploitation of common resources promotes diversity in some circumstances. This situation is investigated further and a more general description is given.</p> <p>A model of single-species growth on two resources is then presented. For a given dilution rate, the medium in the growth vessel is enriched by increasing the input concentration of one of the resources. Enrichment is considered beneficial if the carrying capacity of the environment is increased. Analytic methods are used to determine the effects of enrichment on the asymptotic behaviour of the model for different dilution rates. The existence of a threshold value for the dilution rate is established. For dilution rates below the threshold, enrichment is beneficial, regardless of which resource is used to enrich the environment. When the dilution rate is increased beyond the threshold, it becomes important to consider which resource is used to enrich the environment. For one of the resources it is shown that, while moderate enrichment can be beneficial, sufficient enrichment leads to the extinction of the population. For the other resource, enrichment leads from washout or initial condition dependent outcomes to survival, and is thus beneficial.</p> <p>The growth model is then extended to include a single predator population. Using the threshold value for the dilution rate established in the growth model, the effects of enrichment on the asymptotic behaviour of the resultant predator-prey model are investigated. Here, enrichment is considered beneficial if it can lead from washout for some positive initial conditions to survival of both species for any positive initial conditions. For dilution rates below the threshold, enrichment is beneficial, regardless of which resource is used for enrichment. As in the growth model, it becomes important to consider which resource is used to enrich the environment when the dilution rate is above the threshold. For one of the resources, moderate enrichment can be beneficial, while sufficient enrichment leads to a regime in which washout is possible. For the other resource, sufficient enrichment is beneficial.</p> / Doctor of Philosophy (PhD)

A Rutherford backscattering spectrometry facility has been designed and built at the University of Arizona. Initial calibration and testing has been carried out in order to accurately characterize the system and make it ready to perform reliable analyses. Also, an explanation of basic RBS principles has been presented to enable persons unacquainted with the technique to determine its applicability for various types of analytical problems. A method for determining the concentration profile of Ag in an SiO₂ matrix is carefully explained. Calculations derived from basic principles are demonstrated for this analysis and can be applied in a number of similar circumstances. Several other examples of analyses of utilizing various operating parameters are explained and illustrated. Some examples of unusual samples are shown to be feasible for analysis by this technique. RBS is shown to be a very useful analytical tool for a wide variety of samples. It has the capability of performing quantitative depth profiles without standards. The vast potential for its use by analytical chemists is demonstrated, and future improvements for this particular facility are discussed.

by Chan Wing Fat. / Bibliography: leaves 134-136 / Thesis (M.Ph.)--Chinese University of Hong Kong, 1986