Barytes (the naturally occurring BaSO4) is used as the standard densification agent in drilling fluids world-wide. It increases the density of the drilling fluids for control of formation pressures. It has been highlighted as a major source of toxic heavy metals input in the oil and gas industry. Large scale use in the offshore oil well drilling operations and subsequent discharges of spent drilling fluids containing barytes to the marine environment have raised concerns regarding the potential for bioaccumulation in marine biota of the toxic heavy metals and the possible human health risks. Various analytical and biological aspects of barytes regarding chemistry, analytical methodology, toxicity and heavy metal bioavailability have been thoroughly investigated in this study. Electron probe microanalysis (EPMA) confirms the presence of a number of minerals including barite, galena, anglesite, pyrite, sphalerite, zincite, quartz, barium feldspar, hematite, anhydrite, orthoclase, silicates, mixed minerals in barytes. Quantitative strontium and calcium as part of the crystal lattice whereas other trace heavy metals occur as associated minerals. Image analysis shows that the bulk of barium in barytes corresponds to the mineral barite (BaSO4), however, a small quantity of barium was found to be associated with silicon which confirmed the presence of barium feldspar. The presence of toxic heavy metals such as Cu, Ni, V, Co, Cr, Cd, Bi, Ti, Hg, Te, Sn, Sb, As etc. in barytes is likely to be as inclusions or substitutions in sulphide minerals associated with barite. Mineralogical studies suggest that barytes is not the traditionally inert BaSO4 but, rather, a potentially toxic substance due to its associated toxic heavy metal impurities. Comparative studies on the performance of chemical dissolution procedures such as sodium carbonate fusion, aqua regia digestion, aqua regia /HF digestion and a non-destructive technique, X-ray fluorescence spectrometry shows that sodium carbonate fusion procedure is the best method for the determination of barium in different types of barytes. DTPA and EDTA extractibilities for barium at pHs 12.6 and 10.8 respectively (25oC) were found to be low even though predictions based on thermodynamic data had suggested that BaSO4 should be soluble.

Toxic shock syndrome is a rare complication of Staphylococcus aureus infection associated with small burn wounds of under 5 % total body surface area; it is predominantly observed in young children. Environmental factors that occur within a burn wound have been suggested to increase the risk of TSS developing, and wound dressings have been implicated to contribute to this risk. This study examined the effects of 11 wound dressings on the production of TSST-1 by two strains of S. aureus (strains T1 and T4). Initially, the effects of the wound dressings on growth and exotoxin production were assessed using a liquid culture medium, as this was used in other studies. The results indicated that growth was not markedly affected using this system, however there were a number of problems associated with the evaluation. TSST-l production was altered (increased or decreased) depending upon the dressing type, the gaseous environment or the strain of S. aureus used. Other exotoxins did not appear to be greatly affected by any of the dressings. When a semi-solid system was developed to minimise disintegration of the dressings and simulate a more appropriate wound model in terms of support and environment, similar results were observed as to those found in a liquid culture system. A l-layered semi-solid agarose system incubated in 6 % (v/v) carbon dioxide supported optimum TSST-1 production by both test strains in the presence and absence of most wound dressings. Actisorb Plus™ and crepe increased TSST-l production. Levels of TSST-l increased over time and Actisorb Plus™ continued to stimulate increased toxin production. Gamgee, and Biobrane ™previously implicated. in TSS, increased TSST-1 production t.. . I between 48-72 hours. Serine, thiol and metalloproteases were produced by both strains of S. aureus and proportions of each were altered by the presence of dressings. This study showed that some wound dressings may potentially increase the risk of a patient developing TSS, but further studies need to be done in vivo.

A Thesis submitted to The University of Arizona College of Medicine - Phoenix in partial fulfillment of the requirements for the Degree of Doctor of Medicine. / Stevens - Johnson syndrome and Toxic Epidermal Necrolysis Syndrome are rare, but serious conditions affecting skin and mucous membranes that are primarily treated with supportive care. Other more specific therapies have limited evidence to support the benefit of their use; one such treatment is intravenous immunoglobulin (IVIG). The use of IVIG in the treatment of these syndromes remain controversial due to mixed results demonstrated in the literature, and at present is not considered a component of the standard of care. This study seeks to provide additional data regarding the efficacy of IVIG treatment on mortality in a small cohort of patients presenting with these syndromes at a regional burn center over a 10-year period; data was retrospectively collected from patient medical records. On analysis of this data, IVIG use showed a potential, but not significant. improvement on mortality in comparison to the non-treatment group. Compared with the non-treatment group, odds ratios for death were 0.81 (95% CI 0.3-2.0) for IVIG. There is ultimately no new evidence that the benefit of IVIG in the treatment of Stevens - Johnson syndrome and Toxic Epidermal Necrolysis Syndrome is anything more than potential. Further investigation should include a rigorous analysis and comparison of different dosing regimens.

No description available.

No description available.

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Biosolids from sewage treatment plants present both problems and opportunities for society. They are rich in organic matter, nutrients and trace elements and so can be effective soil conditioners, potentially improving both soil structure and fertility. However, they commonly contain high concentrations of heavy metals, which can accumulate to toxic levels in soils receiving frequent or high dose applications. Copper (Cu) is one of the metals of chief concern because it often has high concentrations in biosolids and is capable of exerting a toxic effect on soil microbes. Limits are placed on the amounts of biosolids that can be applied to land to prevent soil accumulation of metals, but these regulatory limits are based on the total metal concentrations in soils and biosolids rather than on the portion that is ecologically active. Therefore, current regulations do not take into account the fact that much of the metal content is bound up in a way that renders it non-active, and thus poses no threat to the environment. A more environmentally relevant regulatory system would set its limits using the available portion of metals. Therefore it is important to quantify this available fraction, and to establish a method by which it can be consistently measured. To do this the nature of biosolids needs to be better understood, and the factors controlling the available fraction need to be identified. Also, it is important to determine how the available fraction may change with time. This PhD project surveyed 24 biosolids from around Australia and characterised them in terms of chemical and physical properties. Available Cu was measured using radio isotopic techniques (⁶⁴CU), a Cu²⁺ ion selective electrode, solution extraction, and other methods. A model for predicting available Cu was produced, using the total Cu concentration and the Cu²⁺ ion activity in solution extracts: Available Cu (mg/kg) = 281.5 Log Total Cu -14.9 pCu²⁺ 459 (R² = 0.806) where 'logTotal Cu' is IOglO total biosolid Cu concentration (mg/kg). A 21-month incubation experiment was conducted to monitor Cu availability over time, with the conclusion that it will remain constant if pH is maintained. Biosolidlsoil pH had a strong effect on available Cu, hence a regulatory system based on the available Cu fraction that incorporates a pH protection index is proposed. Mineralisation of organic matter did not lead to increases in available Cu, thus no evidence for the time bomb hypothesis was found. However, organic matter was found to be important for Cu sorption in some biosolids, indicating that over a longer term effects of organic mineralisation on Cu availability may be seen, and therefore longer trials (i.e. > 10 years) are needed to determine the long-term fate of biosolid Cu. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1143456 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2004

Title page, table of contents and abstract only. The complete thesis in print form is available from the University of Adelaide Library. / Biosolids from sewage treatment plants present both problems and opportunities for society. They are rich in organic matter, nutrients and trace elements and so can be effective soil conditioners, potentially improving both soil structure and fertility. However, they commonly contain high concentrations of heavy metals, which can accumulate to toxic levels in soils receiving frequent or high dose applications. Copper (Cu) is one of the metals of chief concern because it often has high concentrations in biosolids and is capable of exerting a toxic effect on soil microbes. Limits are placed on the amounts of biosolids that can be applied to land to prevent soil accumulation of metals, but these regulatory limits are based on the total metal concentrations in soils and biosolids rather than on the portion that is ecologically active. Therefore, current regulations do not take into account the fact that much of the metal content is bound up in a way that renders it non-active, and thus poses no threat to the environment. A more environmentally relevant regulatory system would set its limits using the available portion of metals. Therefore it is important to quantify this available fraction, and to establish a method by which it can be consistently measured. To do this the nature of biosolids needs to be better understood, and the factors controlling the available fraction need to be identified. Also, it is important to determine how the available fraction may change with time. This PhD project surveyed 24 biosolids from around Australia and characterised them in terms of chemical and physical properties. Available Cu was measured using radio isotopic techniques (⁶⁴CU), a Cu²⁺ ion selective electrode, solution extraction, and other methods. A model for predicting available Cu was produced, using the total Cu concentration and the Cu²⁺ ion activity in solution extracts: Available Cu (mg/kg) = 281.5 Log Total Cu -14.9 pCu²⁺ 459 (R² = 0.806) where 'logTotal Cu' is IOglO total biosolid Cu concentration (mg/kg). A 21-month incubation experiment was conducted to monitor Cu availability over time, with the conclusion that it will remain constant if pH is maintained. Biosolidlsoil pH had a strong effect on available Cu, hence a regulatory system based on the available Cu fraction that incorporates a pH protection index is proposed. Mineralisation of organic matter did not lead to increases in available Cu, thus no evidence for the time bomb hypothesis was found. However, organic matter was found to be important for Cu sorption in some biosolids, indicating that over a longer term effects of organic mineralisation on Cu availability may be seen, and therefore longer trials (i.e. > 10 years) are needed to determine the long-term fate of biosolid Cu. / http://proxy.library.adelaide.edu.au/login?url= http://library.adelaide.edu.au/cgi-bin/Pwebrecon.cgi?BBID=1143456 / Thesis (Ph.D.) -- University of Adelaide, School of Earth and Environmental Sciences, 2004

Thesis (doctoral)--University of Uppsala, 1980. / Bibliography: p. 56-63.

Sensors play an important role in industry and in academic research for measurement of various chemical and physical parameters in a variety of environments. Optical materials, whose properties (e.g. absorption, colour) change on interaction with a target analyte, are very useful for sensor applications. Among organic optical materials, there is a class showing electrochromic or solvatochromic properties, which have potential to be used as sensor materials. Normally, organic compounds, with electrochromic or solvatochromic properties, have a conjugated system linking donor and acceptor groups in the molecule. During excitation by a field (electric or light), an intramolecular charge transfer takes place resulting in an excited state with different dipole moment to the ground state. A number of such dye compounds have been synthesised in this work, some of them show considerable electrochromism or solvatochromism, such as 3-ethyl-5-{[1-dodecyl-2(lH)-pyridylidene]-ethylidene}-rhodanine. Its absorption maxima are 524 nm in acetonitrile and 584 nm in ether, having a 60 nm shift. It was found that solvatochromism of such compounds was increased with the increase of the chain length of their conjugated system. The conjugated compounds synthesised were deposited onto a transparent substrate either by solution evaporation or by Langmuir-Blodgett film technology. The films formed did respond to some toxic gases such as NO[2], resulting in an absorption wavelength shift in their uv-vis spectra. Pyridinium N-phenoxide betaine dyes are known as good probes for solvent polarity. The best example is ET(30). ET(30) values have been widely used for polarity measurement of solvents. In order to covalently link these betaine dyes to a solid support for convenience of use, a number of dyes with a functional amino group have been synthesised. This amino group forms the basis for linkage. Additionally, modifications were made to the phenoxide end of the molecule to reduce the phenolate pKa. Dichloro and difluoro variations from the parent diphenyl structure were made. Several methods have been used to try to covalently immobilise the betaine dyes synthesised onto a solid support. Some of them have been successfully immobilised onto a silica sorbent by a thiourea linkage or an amide linkage. Immobilised dyes showed reduced but still good solvatochromism. Their ET values demonstrated linear correlation with standard ET(30) values.

The purpose of this study was to examine the sequence of changes in the gross morphology and toxicity of the raphidophyte alga Heterosigma akashiwo in the context of blooms of this species in the Strait of Georgia, British Columbia. Field work focused on this alga’s 1989 fish-killing bloom. That bloom was extensive, with discolouration of the water extending from Jervis Inlet through Malaspina Strait into the Strait of Georgia, and south to Cypress Island in Washington State. Excystment events on Spanish Banks in Vancouver harbour preceded population development in the Strait of Georgia during July and August but toxicity was only noted in the last two days of August and through September. Fish kills occurred near Cypress Island, and in Jervis Inlet and the contiguous waters of Agamemnon channel. These locations represented the geographic extremes of the discoloured waters. In Malaspina Strait and Jervis Inlet, information was collected on water column structure, macronutrient concentrations, and the distribution of algae and fish mortalities. Fish mortalities were coincident with the first sighting of waters discoloured with Heterosigma akashiwo in Agamemnon Channel and Jervis Inlet. The alga appeared to be transported to the areas by currents. Algal concentrations were higher at the Malaspina Strait end of a transect into Jervis Inlet and during flood rather than ebb tides. The water column in Malaspina Strait and Jervis Inlet was stratified and both inorganic nitrogen and phosphorus in surfece waters were low enough to limit growth of H. akashiwo. Though this alga can migrate vertically to obtain nutrients at depth, there was no evidence of migration during this toxic event. Termination of the bloom was associated with a weakening of the water column stratification and the reappearance of non-limiting concentrations of nitrogen in the surface waters. Work in culture demonstrated that there was a sequence of reproducible changes in cell size and shape that improved uptake when nutrients were at the concentrations seen in the Strait at the start of the toxic bloom. These changes involved reduction in cell volume by a factor of between 2- and 4-fold and cells changing from rounded, almost football-shaped cells (oblate spheroids), to plate-like (prolate spheroids). Mathematical modeling suggests that the volume changes could improve nutrient uptake by a factor of 21 to 38%. The changes in shape could improve nutrient uptake dynamics by a further 7.5%. Depending on the nutrient history of the population, changes in cell shape could continue beyond the plate-like form with significant portions of the algal population developing surface protuberances when adequate nutrients and energy were available to the population. The elaboration of surface processes could further improve uptake dynamics. A numerical model to describe these shapes was not available so the degree of improvement could not be quantified. As cells reach the end of their life cycle in culture, they revert to the oblate spheroid form and, if no new nutrients are added, will form resting cysts. However, cyst formation can also be triggered earlier in the life cycle by the addition of nutrients. This may benefit the species by ensuring that cells form cysts in shallow waters where spring temperatures are adequate to fecilitate excystment of cells. In addition to changes in shape. Heterosigma akashiwo cells produce a toxic agent which can suppress growth of nutrient competitors and kill predators, or make the algae unpalatable. Production of those toxins begins and declines immediately prior to decline in population numbers. Toxic effects of the alga can be caused to disappear at any time by the addition of nutrients. Similar to the differentiation of cell shape, the level of toxicity expressed by the cells appears to be correlated with the nutrient history of the population. Cells grown in higher nutrient concentrations appear to be more toxic; however, the population need not have high numbers of cells with processes to be toxic. Heterosigma akashiwo would appear to have adaptations which enhance its ability to compete and survive in the nutrient-limited waters of late summer. The adaptions include both changes in gross morphology of the cells and in the production of toxins which reduce the effects of competition and predation. Population growth and formation of concentrations of the alga capable of discolouring the water can be independent of the occurrence of toxicity. Lack of vertical migration and a protracted period of a stable, stratified water column with depleted nutrients appear to be critical to the genesis of toxicity in wild populations. / Graduate