Thesis (Ph. D.)--Ohio State University, 1947. / Includes vita. Includes bibliographical references (leaves 97-99). Available online via OhioLINK's ETD Center.

Thesis (M.S.)--Ohio State University, 1931. / Includes bibliographical references (leaves 44-46). Available online via OhioLINK's ETD Center.

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1906. / The entire thesis text is included in file. Typescript. Illustrated by authors. R. F. Rucker determined to be Ray Fleming Rucker and D. D. Dunkin determined to be Damon Duffield Dunkin from "Forty-First Annual Catalogue. School of Mines and Metallurgy, University of Missouri". Title from title screen of thesis/dissertation PDF file (viewed January 26, 2009)

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 (M.S.)--University of Missouri, School of Mines and Metallurgy, 1940. / The entire thesis text is included in file. Typescript. Illustrated by author. Thesis contains no title page. Thesis title and author determined from printing on thesis binding and "Seventieth Annual Catalog. Missouri School of Mines and Metallurgy, University of Missouri". Title from title screen of thesis/dissertation PDF file (viewed March 9, 2010) Includes bibliographical references (p. 90-100).

Thesis (Ph. D.)--Columbia University, 1934. / Vita. Bibliography: p. 45-46.

This project studied the production of barium sulphate nanoparticles through inhibition of crystal growth, during precipitation, by different surfactants. Barium sulphate is the pure form of the ore baryte, which due to its high density and softness, is the most commonly used additive used to increase the density of drilling fluids. A non-agglomerating, stable nano-scale dispersion of barium sulphate particles would have significant technical and commercial impact in the drilling fluids industry. This thesis tested the possibility of precipitating barium sulphate and restricting its crystal growth with inhibitors, creating nanoparticles. Six inhibitors were tested; dodecanoic acid, palmitic acid, stearic acid, adamantane carboxylic acid, methylnonanoic acid and a mixture of phosphate esters known commercially as Fazewet. Precipitated, inhibited barium sulphate was characterised using powder XRD, DRIFT FTIR and solid-state NMR (SSNMR). All inhibitors were shown to form single-phase, orthorhombic barium sulphate crystals proving that the inhibitors affect only the surfaces of precipitated crystals and do not enter the crystal lattice. FTIR allowed the relative adsorbed concentration of each inhibitor to be assessed. The results indicate that adsorbed inhibitor increases with increasing inhibitor concentrations but that their attachment is not proportional to the concentration. In most cases concentrations of 0.1mol l-1 of inhibitor were sufficient to saturate the crystal surface. SSNMR also agreed with this although the sample size was too small, due to equipment restrictions, to make definitive conclusions. Through the use of the Debye-Scherrer equation, the crystallite size was calculated and showed that at concentrations of 0.2mol l-1 all inhibitors other than palmitic acid produced nano-scale (< 100nm) crystallites. Further analysis showed that further reductions could be achieved through precipitation in an alkaline pH environment, with the application of mechanical shear and by using adding 50% v/v of ethanol. iv Laser diffraction particle size analysis showed that the dominant factor in reducing particle size distribution was inhibitor concentration. The volume-based PSD used by the laser diffraction system was considered to distort excessively the particle sizes present and so analysis switched to dynamic light scattering. DLS showed that dodecanoic acid, palmitic acid and stearic acid, despite forming nano-scale crystallites, could not produce a nano-scale dispersion of barium sulphate and as such were unsuitable for use in drilling fluids. Stable nano-scale dispersions were found to have been formed when inhibited with adamantane carboxylic acid, methylnonanoic acid and Fazewet. DLS also confirmed that dispersed particle size rather than simply crystallite size could be reduced with an alkaline pH and high mechanical shear. Concentration was still the dominant effect, however with the smallest particles sizes (ZAvg) being observed at concentrations of 0.6mol l-1. The particle sizes for the three modifiers were approaching that of the crystallite size, suggesting that some further reduction is possible, but large reductions are unlikely. All three inhibitors produced sub 100nm ZAvgs, with the smallest produced by methylnonanoic acid of 43nm. Spherical nanoparticles were observed through the use of ESEM and TEM. Due to equipment time restrictions only 0.2mol l-1 treatment levels could be examined, but ESEM showed apparent nanoparticle clusters, later confirmed using pixel count and SFDA methods. TEM analysis showed discrete particles as small as 3nm, indicating that the lower limit for achievable particle size may be lower than PSD measurements would suggest. The results indicate that adamantane carboxylic acid, methylnonanoic acid and Fazewet sufficiently inhibit crystal growth to be potential candidates for the production of barium sulphate nanoparticles. These three inhibitors produce a barium sulphate dispersion that is stable and nano-scale even after drying and redispersion.

Barium sulphate is a widely used analytical precipitate and for this reason its properties have been extensively studied. The variety of results encountered with barium sulphate samples prepared by different methods is an indication of the complex nature of this interesting substance. Intro., p. 8.

A videofluoroscopia da deglutição (VDF) é um exame considerado padrão ouro como método de avaliação da deglutição que requer que o paciente ingira o contraste de Bário em diferentes consistências para que as fases oral e faríngea sejam avaliadas com maior efetividade. Porém, existe uma disparidade entre a viscosidade dos alimentos com o contraste de Bário para a VDF e os alimentos espessados com o espessante de forma empírica, indicado subjetivamente na terapia de reabilitação. Por isso, o objetivo desse estudo foi: padronizar a quantidade de espessante a ser acrescentado à fórmula infantil nas consistências néctar (N), mel (M) e pudim (P) em 2 temperaturas: ambiente (T1) e variando de 40ºC até 44ºC (T2); comparar os valores médios das viscosidades com as sete marcas dos espessantes mais comumente utilizados e disponíveis (E1, E2, E3, E4, E5, E6, E7) nas temperaturas T1 e T2; identificar a quantidade mínima de contraste de Bário a ser acrescentado à fórmula infantil para boa resolução na videofluoroscopia (50%, 25% e 12,5%) e elaborar um manual de preparo de alimento para VFD nas diferentes consistências (N, M, P) com contraste de Bário. Para a padronização foram utilizados sete marcas de espessantes, uma fórmula infantil de partida, e a média da viscosidade avaliada por meio do viscosímetro Brookfield modelo DV-E, em duas temperaturas (ambiente e acima de 40ºC). Foram avaliadas três diluições (50%, 25% e 12,5%) do contraste de Bário (Bariogel 100%) nos leites espessados por meio de seringas no aparelho de VFD e as imagens obtidas julgadas por duas fonoaudiólogas experientes no exame. Os resultados revelaram que a padronização da quantidade de espessante a ser acrescentado à fórmula infantil para obtenção das consistências néctar, mel e pudim, nas temperaturas testadas, variou com o tipo de espessante, requerendo a orientação de um manual para correta manipulação. Os valores de viscosidade diminuíram com o aumento da temperatura, porém os valores foram mantidos dentro do intervalo proposto pela American Dietetic Association (2002) das consistências néctar, mel e pudim. Embora as três quantidades testadas de contraste de Bário tenham proporcionado imagens visíveis, avaliadas pelos juízes, os mesmos consideraram mais seguras aquelas observadas nas diluições de 25% e 50%, necessitando serem testadas outras situadas neste intervalo, uma vez que na diluição de 50% houve alteração da consistência néctar para mel. Um manual foi elaborado para orientação da padronização dos sete espessantes, nas três consistências e nas temperaturas testadas, bem como a sugestão de diluição do contraste de Bário no intervalo de 25% e 50%. / Videofluoroscopy (VDF) is considered a gold standard exam as an evaluation method for swallowing which requires that the patient ingests the Barium contrast in different consistencies so the oral and pharyngeal stages are evaluated with greater effectiveness. However, there is a difference between the viscosity of food with barium contrast for the VDF and thickened foods with the thickener, indicated subjectively in rehabilitation therapy. Therefore, the aim of this study was to standardize the amount of thickener to be added to infant formula in the following consistencies: nectar (N), honey (M) and (P) pudding in 2 environmental temperatures: (T1) and ranging from-40 degrees C to 44 C (T2); compare the average values of viscosities with seven brands of thickening agents most commonly used and available (E1, E2, E3, E4, E5, E6, E7) at temperatures T1 and T2; identify the minimal amount of barium contrast to be added to infant formula for good resolution in videofluoroscopy (50%, 25% and 12.5%), and elaborate a manual of food preparation to VFD in different consistencies (N, M, P) with Barium contrast. Seven brands of thickeners, an infant formula, and the average viscosity evaluated by Brookfield viscometer model DV-E, in two temperatures (above 40°C and environment) were used for standardization. Three dilutions (50%, 25% and 12.5%) of Barium contrast (Bariogel 100%) were used to evaluate the thickened milk by syringes into the VFD and the images obtained judged by two experienced speech language pathologists. Results revealed that the standardization of the amount of thickener to be added to infant formula to obtain the nectar, honey and pudding consistencies, in tested temperatures, varied according to the type of thickener, requiring the use of a manual for correct handling. Viscosity values decreased with increasing temperature, but the values were maintained within the range proposed by the American Dietetic Association (2002) regarding nectar, honey and pudding consistencies. Although the three tested quantities of Barium contrast have provided visible images, evaluated by the judges, those observed in dilutions of 25% and 50% were considered safer. It demanded tests in others situated in this range once in the dilution of 50% there was a change from nectar to honey consistency. A manual has been prepared for the guidance on the standardization of seven thickeners, in the three tested.

Barium sulfate scaling can cause many oilfield problems leading to loss of well productivity and well abandonment. Currently, diethylene triamine pentaacetic acid (DTPA) is used, along with synergist oxalic acid and potassium hydroxide, to remove the scale by dissolution. However, the chemical factors affecting this reaction are not known fully, leading to mixed results in terms of treatment effectiveness. This thesis investigates the effect of these factors, by analyzing the change in barite dissolution due to intrinsic factors like variations in formulation composition and extrinsic factors like presence of competing ions. The dissolution reaction is carried out, by taking the barite powder and chelant solution in a teflon round bottom flask and measuring the barite dissolved periodically, with an ICP-OES. The effect of different factors is studied by varying each factor individually and plotting the changes in solubilities. These lab tests show that solubility of barite (0.01mM in water), ideally, increases with increasing concentrations of chelating agents, even going as high as 239 mM. However experimental or field constraints lead to significant decrease in dissolution, especially at higher chelant concentrations. Thus, field tests to determine most effective chelant concentrations must precede treatment design. Lab tests also show that combination of DTPA with weaker chelating agents like ethylene diamine tetraacetic acid (EDTA), L-glutamic acid, N,N-diacetic acid (GLDA) or methyl glycine diacetic acid (MGDA) reduces barite dissolution and should be avoided during treatment design. Addition of synergists to the formulations, initially improves dissolution performance, especially for moderate chelant concentrations, but proves detrimental and hence must be avoided, over longer treatments. Finally, presence of competing ions in seawater, calcium sulfate and calcium carbonate, can significantly reduce barite dissolution and must be carefully studied for each formation-fluid system before design of treatments. Thus, this project sets a framework to identify the best chelant formulation and estimate its dissolution profile to ensure, a more informed treatment design for barite scale removal.