Thesis (Ph. D.)--School of Chemical Engineering, Georgia Institute of Technology, 2004. Directed by W. James Frederick, Jr. / Vita. Includes bibliographical references (leaves 191-196).

Thesis (Ph. D.) in Chemical Engineering--University of Maine, 2002. / Includes vita. Includes bibliographical references (leaves 166-171).

Absence of stearoyl-CoA desaturase-1 (SCD1) in mice leads to chronic inflammation of the skin and increased susceptibility to atherosclerosis, while also increasing plasma inflammatory markers. A recent report suggested that SCD1 deficiency also increases disease severity in a mouse model of inflammatory bowel disease, induced by dextran sulfate sodium (DSS). However, SCD1-deficient mice are known to consume increased amounts of water, which would also be expected to increase the intake of DSS-treated water. The aim of this study was to determine the effect of SCD1 deficiency on DSS-induced acute colitis with DSS dosing adjusted to account for genotype differences in fluid consumption. Wild-type controls were treated with 3.5% DSS for 5 days to induce moderately severe colitis, while the concentration of DSS given to SCD1-deficient mice was lowered to 2.5% to control for increased fluid consumption. Colonic inflammation was assessed by clinical and histological scoring. Although SCD1-deficient mice consumed a total intake of DSS that was greater than that of wild-type controls, colonic inflammation, colon length and fecal blood were not altered by SCD1-deficiency in DSS-induced colitis, while diarrhea and total weight loss were modestly improved. Despite SCD1 deficiency leading to chronic inflammation of the skin and increased susceptibility to atherosclerosis, it does not accelerate inflammation in the DSS-induced model of acute colitis when DSS intake is controlled. These observations suggest that SCD1 deficiency does not play a significant role in colonic inflammation in this model. [The original version of this article, along with updated information and services is located on the World Wide Web at: http://dx.doi.org/10.1016/j.bbalip.2009.08.001]

No description available.

It has been a practice to use seawater for preparing acid in offshore operations where fresh water is relatively expensive or logistically impossible to use. However, hydrochloric acid will release calcium ion into solution, which will combine with sulfate ion in seawater (greater than 3000 ppm) and calcium sulfate will precipitate once it exceeds its critical scaling tendency. A few studies have provided evidence for this problem and how to address this problem has not been fully examined. Core flood tests were conducted using Austin Chalks cores (1.5 in. x 6 in. and 1.5 in. x 20 in.) with permeability 5 md to investigate the effectiveness of scale inhibitor. A synthetic seawater was prepared according to the composition of seawater in the Arabian Gulf. Calcium, sulfate ions, and scale inhibitor concentrations were analyzed in the core effluent samples. Solids collected in the core effluent samples were analyzed using X-ray photoelectron spectroscopy (XPS) technique and thermodynamic calculation using OLI Analyzer software were conducted to identify the critical scaling tendency of calcium sulfate at different temperatures. Results showed that calcium sulfate precipitation occurred when seawater was used in any stage during matrix acidizing including preflush, post-flush, or in the main stage. Injection rate was the most important parameter that affected calcium sulfate precipitation; permeability reduction was significant at low flow rates, while at high rates wormhole breakthrough reduced the severity of the problem. More CaSO4 precipitated at high temperatures, accounting for more significant permeability reduction in the cores. The values of critical scaling tendency at various temperatures calculated by OLI ScaleChem 4.0.3 were believed to be 2.1, 2.0, and 1.2 respectively. A scale inhibitor (a sulfonated terpolymer) was found to be compatible with hydrochloric acid systems and can tolerate high concentration of calcium (30,000 mg/l). Analysis of core effluent indicated that the new treatment successfully eliminated calcium sulfate scale deposition. The concentration of scale inhibitor ranged from 20 to 250 ppm, depending on the scaling tendencies of calcium sulfate. This work confirms the damaging effect of preparing hydrochloric acid solutions using seawater on the permeability of carbonate cores. Therefore, it is recommended to use fresh water instead of seawater to prepare HCl acids whenever possible. If fresh water is not available, then a proper scale inhibitor should be added to the acids to avoid calcium sulfate precipitation.

All the warm deserts of the world exhibit gypsum crusts in favourable localities, generally areas with a source of gypsum and less than 250 mm of rainfall annually. The features, comprising loose powdery or cemented crystalline accumulations of calcium sulphate dihydrate, are found at the surface or within the uppermost 10 m of regolith. Thicknesses vary from a few millimetres to several metres and purities range from about 15% to nearly 100% gypsum. A review of the literature on gypsum soils and crusts reveals that the classification of types requires both standardizing and simplifying. A preliminary classification of crusts into three types can be made on the basis of structural and stratigraphic characteristics of examples from southern Tunisia and the Central Namib Desert. The types consist of subaerial aqueous evaporites, two subsurface and three surface forms. Detailed physical and chemical analyses justify a broadly similar genetic classification though one subsurface form is believed to be a primary pedogenic type of which the surface forms represent relics at various stages of solutional deterioration. Examples of subaerial aqueous evaporites are all products of shallow-water sedimentation in seasonally flooded chotts and sabkhas. The non-pedogenic subsurface type, croûte de nappe, is produced by displacive crystallization at the surface of a fluctuating water table. Gypsum precipitation results from either evaporation or mixing of saline waters causing saturation with respect to gypsum. Surface gypsum crusts are subsurface illuvial accretions exposed by erosion of overlying material. The gypsum is derived from solution of surface aeolian, atmospheric, colluvial or alluvial deposits by meteoric waters which percolate into the upper soil zone replenishing the antecedent soil moisture deficit. Subsurface accumulation results from displacive crystallization at host sediment grain contacts when gypsum saturated soil moisture evaporates.

Thesis (Ph.D.)--McMaster University, 2002. / Advisor: A. Hrymak. Also available via World Wide Web.

Thesis (Ph.D.)--McMaster University, 2002. / Advisor: A. Hrymak. Also available via World Wide Web.

Thesis (Ph. D.)--University of Washington, 2007. / Vita. Includes bibliographical references (p. 118-138).

Thesis (M.S.)--Auburn University, 2008. / Abstract. Vita. Includes bibliographical references (p. 104-113).