Thesis (M.S.)--University of Wyoming, 2009. / Title from PDF title page (viewed on Apr. 15, 2010). Includes bibliographical references (p. 51-58).

Thesis (doctoral)--Universität Leipzig, 1907. / Vita. Includes bibliographical references.

Thesis (M.S.)--University of Wyoming, 2007. / Title from PDF title page (viewed on June 11, 2009). Includes bibliographical references (p. 36-40).

Thesis (M.S.)--Ohio State University, 1956. / Includes bibliographical references. Available online via OhioLINK's ETD Center

Thesis (M.S.)--University of Florida, 2004. / Title from title page of source document. Document formatted into pages; contains 76 pages. Includes vita. Includes bibliographical references.

(1) The ammonium, potassium and sodium salts of three complex thorium oxalates were prepared and studied. (2) Their solubilities and conditions of stability were studied. (3) The reaction between thorium and excess oxalate, and vice versa, was studied by means of conductivity and high frequency conductivity measurements. (4) The formation constant of Th(C₂O₄)₄⁴⁻ and Th(C₂O₄)₃²⁻, and the solubility product of (NH₄)₂Th₂(C₂O₄)₅, were determined by a solubility method.

The mixed metal oxalates, FeCu(ox)₂.3H₂0, CoCu(ox)₂.3H₂0, and NiCu(ox)₂.3.5H₂0, [ox = C₂0₄] have been prepared by coprecipitation from solution. The thermal behaviour of these compounds in nitrogen and in oxygen has been examined using thermogravimetry (TG), thermomagnetometry (TM), differential scanning calorimetry (DSC) and evolved gas analysis (EGA), and results are compared with results obtained for Cuox and Mox.yH₂0. The thermal behaviour of the mixed oxalates, MCU(OX)₂.xH₂0, differed from that of the individual metal oxalates, Cuox, Coox.2H₂0, Niox.2H₂0 and Feox.2H₂0. All three mixed oxalates on heating in N₂, first dehydrate and then decompose in at least two overlapping endothermic stages. Both CO and CO₂ were evolved in proportions which varied with the surrounding atmosphere, and from compound to compound, and with extent of reaction of a given compound. The mixed oxalates, MCU(OX)₂.xH₂0, do not show the exothermic behaviour characteristic of Cuox, and reasons for this are discussed. Thermochemical calculations were done and the enthalpies of formation of the hydrates and dehydrated oxalates were determined. It was found that the enthalpy of mixing was very small or within experimental error. X-ray powder diffraction patterns for the individual and mixed oxalates were compared. The pattern for Cuox differs from the patterns obtained for the other oxalates, confirming suggestions that Cuox has a structure different to most other transition metal oxalates. The kinetics of dehydration and decomposition of the mixed oxalates were investigated, using isothermal and programmed temperature TG and DSC experiments. The yield and composition of evolved gases during isothermal decomposition were measured and compared with the enthalpy changes. X-ray photoelectron spectroscopy studies provided some information on the electron environment of the metal atoms in the various oxalates.

Thesis (Ph.D.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 122 pages. Includes vita. Includes bibliographical references.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Avaliou-se a eficiÃncia do uso do oxalato de potÃssio (BisBlock â Bisco) em restauraÃÃes de lesÃes cervicais nÃo-cariosas. Para a realizaÃÃo do estudo, foram selecionados vinte pacientes voluntÃrios de ambos os sexos, com idades entre vinte e quatro e cinquenta e cinco anos, com no mÃnimo duas lesÃes que foram restauradas com as tÃcnicas a serem avaliadas. Noventa dentes foram aleatoriamente divididos em dois grupos, a saber: Grupo 1 - RestauraÃÃo pela tÃcnica convencional com o condicionamento Ãcido total e Grupo 2 - RestauraÃÃo com prÃ-tratamento de oxalato de potÃssio seguido da aplicaÃÃo do sistema adesivo. O sistema restaurador adesivo empregado foi o XP Bond (Dentisply) â Durafill (Kulzer). Para a realizaÃÃo das avaliaÃÃes clÃnicas, foi empregado o mÃtodo USPHS modificado, levando-se em consideraÃÃo os seguintes critÃrios: retenÃÃo (R), integridade marginal (IM), descoloraÃÃo marginal (DM), sensibilidade pÃs-operatÃria (S), cÃrie (C), forma anatÃmica (FA). As avaliaÃÃes clÃnicas foram realizadas por dois avaliadores nos perÃodos imediato (Baseline), seis meses e um ano. A intensidade da sensibilidade dolorosa foi avaliada antes e apÃs o tratamento utilizando-se uma escala de medida verbal. Ao final de um ano, os resultados de restauraÃÃes clinicamente satisfatÃrios (Alfa e Bravo) obtidos para o grupo controle e experimental foram respectivamente: R (97%/89%), IM (100%/100%), DM (100%/100%), S (100%/100%), C (100%/100%), FA (100%/100%). Os resultados foram submetidos à anÃlise estatÃstica com os testes de Kruskal-Wallis e Mann-Whitney para os nÃveis de sensibilidade e o exato de Fisher para os demais critÃrios com o nÃvel de significÃncia de 5% (p<0,05). Com base na anÃlise estatÃstica dos resultados, conclui-se que o emprego do oxalato de potÃssio como agente de prÃ-tratamento dentinÃrio nÃo influenciou no desempenho clÃnico das restauraÃÃes de lesÃes cervicais nÃo-cariosas ao final de um ano. / The aim of this study was to evaluated the efficiency of the use of potassium oxalate (BisBlock - Bisco) in restorations of non-carious cervical lesions. Twenty volunteers patients of both sexes, aged between twenty-four and fifty-five years old, with at least two lesions that were restored with the techniques to be evaluated were selected. Ninety teeth were randomly divided into two groups: Group 1- Restoration with total-etch technique and Group 2 â Restoration with pre-treatment with potassium oxalate followed by application of adhesive system. The adhesive restorative system used was XP Bond (Dentisply) - Durafill (Kulzer). The clinical evaluation was employed USPHS modified method, taking into account the following criteria: retention (R), marginal integrity (MI), marginal discoloration (MD), postoperative sensitivity (S), caries (C), anatomic form (AF). Clinical assessments were conducted by two examiners in the periods baseline, 6 months and 1 year. The intensity of pain sensitivity was assessed before and after treatment using a verbal rating scale. After one year the results of restorations clinically satisfactory (Alfa and Bravo) obtained for the control and experimental group were: R (97% / 89%), MI (100% / 100%), MD (100% / 100%), S (100% / 100%), C (100% / 100%), FA (100% / 100%). The results were analyzed statistically with Kruskal-Wallis and Mann-Whitney tests for levels of sensitivity and the Fisher exact test for the other criteria with a significance level of 5% (p <0.05). Based on statistical analysis, we conclude that the use of potassium oxalate as an agent of dentin pre-treatment did not influence the clinical performance of restorations in non-carious cervical lesions after one year.

The crystal structure of Ba [Cu(C₂0₄)₂(H₂O)].5H₂O has been determined using single crystal X-ray diffractometry. It crystallises in the triclinic system, space group Pī , with a = 6.539(2) Å, b = 9.211(3) Å, c = 10.928(3) Å, a = 85.42(3)°, β = 79.22(3)° , γ = 80.30(3)°, V = 636.08(8)ų and Z = 2. The structure consists of [Cu(C₂0₄)₂(H₂O)]²⁻ ions weakly bridged by barium ions and water molecules. The copper(II) ions are in a tetragonally elongated square-pyramidal environment with some trigonal distortion. The two oxalate groups occupy the equatorial positions and a water molecule occupies the axial position. The barium ion is surrounded by nine oxygens: five oxygens from water molecules and four oxygens from oxalate groups. The thermal behaviour of Ba [Cu(C₂0₄)₂(H₂O)].5H₂0 in N₂ has been examined using thermogravimetry (TG) and differential scanning calorimetry (DSC). The dehydration starts at relatively low temperatures (~80°C), but continues until the onset of the decomposition (~280°C). The decomposition takes place in two major stages. The mass of the intermediate after the first stage corresponded to the formation of barium oxalate and copper metal and, after the second stage, to the formation of barium carbonate and copper metal. The enthalpy for the dehydration was found to be 311 ±30 kJ mol⁻¹. The overall enthalpy change for the decomposition of Ba[Cu(C₂0₄)₂]in N₂ was estimated from the combined area of the peaks of the DSC curve as -347 kJ mol⁻¹. The kinetics of the thermal dehydration and decomposition were studied using isothermal TG. The dehydration was strongly deceleratory and the α-time curves could be described by the three-dimensional diffusion (D3) model. The values of the activation energy and the pre-exponential factor for the dehydration were 125 ±4 kJ mol⁻¹ and (1.38 ±0.08)x10¹⁵ min⁻¹, respectively. The decomposition was complex, consisting of at least two concurrent processes. The decomposition was analysed in terms of two overlapping deceleratory processes. One process was fast and could be described by the contracting-geometry model with n = 5. The other process was slow and could also be described by the contracting-geometry model , but with n = 2. The values of Eₐ and A were 206 ±23 kJ mol⁻¹ and (2.2 ±O.5)xl0¹⁹min⁻¹, respectively, for the fast process, and 259 ±37 kJ mol⁻¹ and (6.3 ±1.8)x10²³min⁻¹, respectively, for the slow process.The crystal structure of zinc oxalate dihydrate ([Zn(C₂0₄)(H₂O)₂]n) has also been determined by X-ray diffraction methods. It crystallises in the monoclinic system, space group C2/c with a = 11.786(2) Å, b = 5.397(1)Å, c = 9.712(1) Å, B = 126.19(5)°, V = 498.58(8)ų, Z = 4 and R = 0.037 for 435 absorption-corrected independent reflections and 50 parameters. The asymmetric unit consists of half the monomeric unit [Zn(C₂0₄)(H₂O)₂). The structure consists of infinite, linear chains of zinc ions bridged by oxalate groups. The geometry of the coordination polyhedron surrounding the zinc ion is octahedral, with the oxalate oxygens occupying the equatorial positions and water molecules occupying the axial positions.