Call number: LD2668 .T4 1966 M215 / Master of Science

The ability of wheat bran and oat hulls to bind copper and zinc using a new chromatographic technique was investigated and compared to a centrifugation method. Also investigated was the bioavailability of copper which had been exogenously bound to wheat bran then fed to mice and rats. Wheat bran bound 6 mg Cu/g fiber when pH was raised to 7. Less binding occurred at lower pHs. Seven mg of zinc bound to wheat bran at pH 5 while only a trace bound at pH less than 2. Oat hulls bound 3 mg Cu/g fiber at pH 5, and less than 1 mg of zinc bound per g of oat hull at pH 6. Binding for both fibers depended on the level of mineral added to the fiber slurry during incubation. But only wheat bran binding capacity was influenced by pH. The two methods used did not compare favorably, in all cases, to the amount of mineral bound to fiber. Copper when bound to wheat bran, was utilized in both species, with differences occurring between species was noted. Rats fed the copper bound diet compared favorably with rats fed the copper-adequate diet as determined by body weight, weight gain, heart weight, liver copper concentration and heart copper concentration. Mice, on the other hand showed similar liver and heart concentrations of copper for mice fed either the copper-bound diet or the copper-adequate diets. The in vitro results showed that binding of copper or zinc to wheat bran occurred at a pH similar to the intestinal pH and wheat bran binds more copper and zinc than oat hulls. Oat hulls may prove to be a better dietary fiber source for those people who need to increase their dietary fiber, because oat hulls do not appear to bind copper or zinc and would not likely impair their absorption. Although wheat bran had a high binding capacity for copper, this binding did not significantly inhibit copper absorption as determined in animal studies suggesting that fiber-mineral binding (at least for copper bound to wheat bran) does not cause mineral deficiency symptoms as claimed by many researchers.

The debate of whether to standardise or to custom-tailor marketing strategies and tactics in international markets has continued to trouble academics and practitioners alike and has produced many and varied opinions. Supporters of global standardisation argue that a single marketing strategy and a standardised marketing mix (tactics) should be used in international markets to minimise total costs and promote a global corporate image. In contrast, advocates of international adaptation debate that marketing in overseas markets should be adapted to fit the unique dimensions of each local market. Opposing the two polarised positions, literature quoting practical evidence suggests that companies make contingency choices which relate to key determinants in each circumstance. This doctoral research focuses on the tactical level. It hypothesises that multinational companies' tactical behaviour is integrated as a result of several reasons `pulling' it towards the one or the other side of the continuum. Equally, it proposes that such behaviour and the importance of reasons `pulling' it, could be significantly different based on nine factors. Consequently, this research seeks to discover the unique way in which the reasons and factors interact with international marketing tactics in any given `country and company situation'. A review of the literature (chapters two and three) allowed the development of a framework (chapter three) that presents the main perspectives of the different schools of thought towards the processeso f adaptation,s tandardisationa nd integration of marketing tactics. Its formulation made possible two main stages in this research: it firstly allowed the researcher to formulate the secondary hypotheses, and secondly it permitted the design of a questionnaire to test these hypotheses and carry out the necessary empirical research and collection of primary data. Based on the Positivist philosophy, the research design (chapter four) involved a questionnaire survey on the 500 biggest UK multinational companies across five industrial sectors. The analysis (chapters five and six) was mainly quantitative and was undertaken with S. P. S. S. and Excel statistical packages. It utilised chi-square (x2) and analysis of variance (ANOVA) statistical tests. Research results identified that UK multinational companies do not solely utilise adaptation or standardisation across their marketing mix elements. When facing the dilemma of implementing marketing tactics, the researched UK multinational companies were found to integrate the processes of adaptation and standardisation. Both processes co-exist and multinational companies are striking to find a balance. This research identified that the level of integration is dependent upon a consideration of the relationship between the reasons and elements identified, and an understanding of how these are affected by a number of factors. Followed the results of the analysis, this thesis proposes a new modelling approach, the AdaptStand Process (chapter seven), which outlines different steps to be undertaken by multinational companies towards identifying the degree of integration across the marketing mix elements. Consequently, this thesis aims to enlarge the existing body of knowledge in the subject area and guide marketing directors acid managers in deciding on marketing tactics when competing in the international marketing arena.

This thesis has addressed several gaps in the knowledge with regards to the calcium looping cycle for carbon dioxide capture, including identification of engineering challenges associated with the scale-up of the technology to pilot scale and beyond; assessment of changes in sorbent morphology during the pilot scale capture process; and partitioning of elemental impurities in the limestone between the solid and gaseous phase during the carbon dioxide capture process. Hydrodynamic investigations identified the optimum superficial velocities required for the reactor in order to optimise solids entrainment and flux, and to minimise gas bypassing. Estimations made in determining how particle attrition would affect minimum fluidisation velocity confirmed a decrease of approximately 0.09m/s for every 5 % reduction in particle size. Amendments made to the exhaust diameter and position, and the loop seals, improved the pressure balance of the system thus enhancing solids transfer. Reactor and process modifications, including modification of carbonator temperature, and maintenance of temperature above 420°C in standpipes resulted in improved carbon dioxide capture %. Increasing bed inventory had a positive effect of carbon dioxide capture % due to an increased Ca looping ratio. Steam addition also benefitted the carbonation process, due to improved sorbent morphology and therefore carbon dioxide diffusion into the sorbent. Sulfur dioxide was considered to have a detrimental effect on carbon dioxide capture due to pore pluggage, although burner- derived steam had a positive effect in maintaining capture %. Gaseous elemental emissions from the process were low for all elements, but concentrations of elements in the solid sorbent phase were influenced by bed inventory, implying that filtering systems may be required in industry for the large masses of sorbent required. Concentrations of elements in the sorbent were identified to be below levels typical of cement, with the exception of Ni, implying that there is potential for spent sorbent to be used in the cement industry with adequate mitigation measures in place.

published_or_final_version / Chemistry / Master / Master of Philosophy

No description available.

Liver glutathione peroxidase activity is affected by changes in selenium (Se) status. To investigate the effect of Se status on GSH-Px protein we prepared antibodies against rat liver GSH-Px and used them in an ELISA. The immunoreactivity of the anti-GSH-Px antibodies against GSH-Px was both tissue and species specific. When rats were depleted of Se, liver GSH-Px activity decreased exponentially to zero with a half-life of 2.8 d. Liver GSH-Px protein also decreased exponentially, but not to zero, with a longer half-life of 5.2 d. Dietary repletion of Se-deficient rats with 0.5 mg Se/kg diet increased GSH-Px protein and activity after 1 d. After 14 d of repletion the levels of GSH-Px protein and activity had plateaued at the levels present in Se-adequate rats. When Se-deficient rats were injected with 15 or 60 ug Se, only rats injected with 60 ug Se and killed 24 h later showed an increase in GSH-Px protein and activity. These results suggest that when Se is limiting, GSH-Px protein and GSH-Px activity are coordinately regulated by the available Se, but in Se-adequacy homeostatic processes control the level of GSH-Px.

The effects of dietary methionine (Met) on the utilization of selenium (Se) from stored tissue Se and dietary selenomethionine (SeMet) for glutathione peroxidase (GSH-Px) synthesis were studied in male rats. Plasma, liver and muscle Se significantly increased when rats were fed 0.5 mg Se/kg diet as SeMet in a Met-deficient diet for 21 d, whereas tissue GSH-Px activities decreased 43-50% during the SeMet supplementation period, suggesting that Se is deposited as SeMet in general body proteins. By calculation, a significant lower percentage of Se was associated with GSH-Px in Met-deficient as compared to Met-supplemented rats. Dietary Met supplementation increased the incorporation of 75Se from 75SeMet into specific rat selenoproteins in addition to liver GSH-Px. Overall, these results suggest that intact SeMet is preferentially incorporated non-specifically into general body proteins in Met-deficient rats, whereas with supplemental Met, more SeMet is degraded and the released Se used for specific selenoprotein synthesis. (Abstract shortened with permission of author.)

No description available.

Arsenic (As) is a carcinogenic agent that is present in varying levels in environmental matrices including water and food. Long term As exposure can lead to skin lesions, peripheral neuropathy, diabetes, renal system effects and cardiovascular diseases. Bio-monitoring of human urine, toenail, serum and cerebrospinal fluid was carried out in this thesis to assess the exposure to arsenic and other trace elements. A multidisciplinary approach based on Inductively Coupled Plasma Mass Spectrometry (ICP-MS), HPLC-ICP-MS and Proton-Nuclear Magnetic Resonance Spectroscopy (1H-NMR) in conjunction with a questionnaire based survey was employed. The impact of rice consumption (a well-known vector of arsenic in the general population) on human urinary As levels was assessed. Results obtained show that the Bangladeshi (UK-B) community in the United Kingdom, who consume ca. 30-fold more rice than the white Caucasians (UK-C), are exposed to a higher level of arsenic. ICP-MS and HPLC-ICP-MS revealed a significant increase in dimethylarsinic acid (DMA) and inorganic arsenic (iAs) species in UK-B compared to UK-C, while cationic compounds were lower in UK-B than in UK-C. DMA and iAs levels in the Bangladeshis were positively correlated to rice consumption. Rice is likely to be responsible for the increase in levels of DMA and iAs in urine of UK-B. The link between this and the disproportional occurrence of diabetes and cardiovascular diseases (CVD) in UK-B needs to be investigated. Another important finding of this study is that the DMA to monomethyl arsenic (MA) ratio, which is often used as an indication of arsenic methylation capacity, should be applied with caution in populations consuming large quantities of rice because variation in the quantity and type of rice eaten may alter the urinary DMA levels and thereby the DMA/MA ratio. Urinary arsenic, selenium, copper and zinc were monitored for a group of Bangladeshis, Pakistanis, Indians and Caucasians living in the UK. The most striking finding was the increase in urinary copper in the UK-B group compared to other ethnicities and to reference values reported for the general UK population. Among the possible reasons for this could include dietary exposure via ethnic food consumption or a change in copper metabolism in the Bangladeshis. High serum copper levels have been correlated to CVD in the US population. In this context, further work is recommended to investigate if there is a relationship between urinary copper and the disproportionately high incidence of CVD in UK Bangladeshis. An approach based on 1H-NMR was used to detect changes in human urinary metabolomic profile as a function of As exposure through different routes. For this, the urine of UK-B, UK-C and a group residing in Bangladesh (BD-B) were monitored. The effects of other factors were explored, including arsenic urinary profile, chewing pan, ethnicity, rice consumption, selenium and diabetes. The three populations show distinctive metabolomic profiles. Urinary arsenic speciation was used in evaluating the effects of arsenic on the metabolomic profile for the UK group. This revealed that the %DMA positively correlates to %N,N-dymethylglycine, %alanine and %betaine. Comparative analysis of the 1H NMR spectra revealed that the BD-B urinary profiles were depleted in the number and quantity of metabolites. Visible signs of lower protein intake and undernourishment emerged from the urinary metabolomic profile of BD-B including a 2.5 decrease in creatinine levels compared to UK-B. Urinary creatinine and the metabolomic profile provide evidence for undernourishment in the BD-B population group that was not evident from previous studies on dietary protein intake in this population performed using food frequency questionnaires. Public health officials might consider also using bio-monitoring studies for nutrient intake rather than solely relying on estimations from food frequency questionnaires. The results reveal the complexity of the subject and pave the way for future studies, highlighting the need for awareness about diet and other specific confounding factors. Multiple Sclerosis (MS) is considered a multifactorial disease and its cause remains unknown. A case-control study on a MS cluster from the volcanic region of Mt. Etna (a natural emitter of geogenic trace elements in the environment) was undertaken. Urine and toenails were monitored for trace elements along with food consumption and life-style habits. Levels of a range of trace elements were reported for the first time for a population living in the Mt. Etna region. No significant differences were found in trace element levels in urine and toenails of MS patients and controls. However, urinary levels of nickel, manganese and selenium were higher than those reported in the literature for the general population from Italy, Germany and the UK. These findings and observations might suggest a role for nickel in the pathology of MS. However, larger studies on the possible role of nickel on MS, and trace elements in general, should be performed. Cerebrospinal fluid (CSF) and some serum from MS patients and controls from the Mt. Etna region were also monitored in this study using ICP-MS. There were significant differences in the trace elemental profile of CSF of MS volunteers and controls, including an increase in arsenic and zinc in the CSF of MS patients. Lead, aluminium, cadmium and molybdenum were significantly increased in the CSF of MS patients as well. In contrast, selenium was lower in MS patients compared to controls. The enrichment of certain trace elements in the CSF of MS patients could be the result of an impairment of the blood brain barrier and tight junction disruption due to MS and its progression, resulting in serum protein leakage and trace elements across the blood–brain barrier. Studies are necessary in the future to identify the chemical species present in the CSF and also determine their role in biological processes including their harmful effects on the brain.