Thesis (M.A.)--Boston University / PLEASE NOTE: Boston University Libraries did not receive an Authorization To Manage form for this thesis or dissertation. It is therefore not openly accessible, though it may be available by request. If you are the author or principal advisor of this work and would like to request open access for it, please contact us at open-help@bu.edu. Thank you. / A photolytic method is developed for the homogeneous precipitation of barium sulfate. The method involves the addition of excess barium, as the EDTA complex, to the sulfur sample. An ammonium slycinate buffer is used to control the pH value and ammonium chloroacetate is added as the photo-sensitizing reagent. Irradiation of the mixture with 2537 radiation results in hydrolysis of chloroacetate with subsequent pH lowering and slow generation of barium sulfate precipitate. Precipitations were essentially complete after five hours. Easily filtered precipitates were obtained after digestion with a larse portion of ammonium nitrate. Photo-micrographs of the undigested precipitate indicate crystallines five to ten microns in diameter. Digestion of the precipitate results in formation of crystalline aggregates up to one hundred microns in diameter. After ignition, the precipitate was suitable for direct weighing and could be used as a basis for gravimetric sulfate determination. Samples containing between 10 milligrams and 120 milligrams of sulfate could be determined with an accuracy of ±0.2% or better. The precision of individual analyses was ±1 milligram sulfate for large samples and ±0.4 milligrams sulfate for smaller samples. / 2031-01-01

Thesis (Ph.D.)--Boston University / Purpose: It was the purpose of this study to test hypotheses concerning the effects of amphetamine sulfate on certain areas of behavior and school performance of hyperactive children. The literature inciicated that some children were observed to be less active and less impulsive and to have greater emotional control and a longer attention span when given amphetamine sulfate. No diagnostic criteria had been established to determine with which children this medication was effective, although many observers felt that the predicted effect occurred with children suffering from an organic cerebral dysfunction. A preliminary study by this writer to investigate the hypothesis that the administration of amphetamine sulfate to children suffering from organic cerebral dysfunction produced more efficient behavior, produced inconclusive results. It suggested that hyperactivity was the factor which differentiated between those children who would show the predicted behavioral changes with amphetamine sulfate and those who would not. [TRUNCATED]

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Concrete structures are often exposed to sulfates, which are typically found in groundwater and soils, in agricultural run-off, in industrial facilities, and in other source points. These sulfates may attack concrete and significantly shorten the service life of concrete due to reactions between sulfate ions and concrete constituents. These reactions form expansive and deleterious compounds that lead to cracking and spalling of the concrete. This reaction is a function of the sulfate solution but also the physical, chemical, and mineralogical properties of the cement and supplemental cementitious materials (SCMs). It is widely understood that the addition of some fly ashes, by-products of coal combustion power plants, improve the sulfate resistance of the concrete but some fly ash additions actually reduce the sulfate resistance. This project aims to understand this relationship between fly ash and sulfate resistance. Using sulfate testing results on mortar previously obtained at The University of Texas at Austin, this research evaluated the mineralogical, chemical, and physical characteristics of fly ash and attempted to link these measured characteristics (or combinations thereof) to sulfate resistance of concrete. / text

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Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2006. / Includes bibliographical references (p. 137-140).