Thesis (M. Ed.)--University of Hong Kong, 1988. / Includes bibliographical references (leaf 135-144).

Thesis (Ph.D.)--Chemical Engineering, Georgia Institute of Technology, 2008. / Committee Chair: Charles A. Eckert; Committee Co-Chair: Charles L. Liotta; Committee Member: Christopher W. Jones; Committee Member: Facundo M. Fernandez; Committee Member: Thomas F. Fuller.

Thesis (Ph. D.)--University of Washington, 2000. / Vita. Includes bibliographical references (leaves 161-171).

Thesis (Ph.D.)--Mississippi State University. Department of Chemistry. / Title from title screen. Includes bibliographical references.

Thesis (Ph.D.)--Aberdeen University, 2009. / Title from web page (viewed on Oct. 7, 2009). Includes bibliographical references.

Thesis (Ph. D.)--University of Delaware, 2007. / Principal faculty advisor: Darrin J. Pochan, Dept. of Materials Science & Engineering. Includes bibliographical references.

Orientador: Milton Carlos Kuga / Resumo: O objetivo dos estudos são avaliar a capacidade de limpeza superfie dentinaria impregnada por AH Plus e MTA Fillapex, proporcionada pelo etanol a 95,0% (E) ou xilol (X) e seus efeitos sobre a interface adesiva e resistência de união do sistema adesivo etch-and-rinse, com condicionamento ácido (CA) imediato (I) ou após 7 dias (T). Publicação 1: Cinquenta espécimes de coroas de incisivos bovinos foram impregnados com o cimento e divididos em quatro grupos (n=10): G1(EICA), E e CA imediato; G2(XICA), X e CA imediato; G3(ETCA), E e CA após 7 dias e G4(XTCA), X e CA após 7 dias e G5(controle), CA imediato. Escores foram atribuídos, em relação à persistência de resíduos na dentina, por análises em MEV(500X). Cinquenta fragmentos foram preparados, restaurados com resina composta e obtidas imagens em microscopia confocal laser (1024X), para avaliar a formação de camada hibrida, mensurada no Image J. Cinquenta fragmentos foram igualmente preparados e submetidos ao teste de microcisalhamento para avaliar os efeitos sobre a resistência de união do sistema adesivo etch-and-rinse na dentina. Em relação à persistência de resíduos, G1 e G2 apresentaram maiores valores que G3 e G4 (P<0,05). Entre G1 e G2 ou G3 e G4 não houve diferença (P>0,05). Em relação à interface adesiva, a extensão da formação da camada hibrida foi G5>G4=G3=G2=G1. Em relação à resistência de união do sistema adesivo G5=G4 e G4=G2 (P=0,05), porém G5>G2 (P<0,05) e G1=G2=G3 (P>0,05). Publicação 2: Cinquenta espécimes de co... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The aim was to evaluate the cleaning protocol in dentin impregnated with different endodontic sealers using 95% ethanol (E) or xylol (X) and its effects on adhesive interface and on bond strength of etch-and-rinse adhesive system when the acid etching (AE) was immediately (I) carried out or 7 days delay (D).Publication 1:Fifty bovine incisors specimens were impregnated with epoxy resin-based sealer (AH Plus) sealer and divided into four groups (n = 10): G1 (EIAE); G2 (XIAE); G3 (EDAE); G4 (XDAE) and G5 (control, IAE). The persistence of residues was evaluated using scores by SEM (500X). Fifty fragments were prepared similarly as described before, restored with composite resin and subjected to laser confocal microscopy (1024X). The hybrid layer formation was measured using Image J program. Another fifty fragments were similarly prepared and submitted to microshear bond test to access the bond strength of etch-and-rinse adhesive system to dentin.Regarding the persistence of residues, G1 and G2 presented higher values than G3 and G4 (P<0.05). No statistical difference was found between G1 and G2 or G3 and G4 (P>0.05). Regarding the adhesive interface, the extend of hybrid layer formation G5>G4=G3=G2=G1.Regarding the bond strength of adhesive system: G5=G4 and G4=G2 (P=0.05), however G5>G2 (P<0.05) and G1=G2=G3 (P>0.05).Publication 2: Fifty bovine crown specimens were impregnated with mineral trioxide aggregate-based (MTA) sealer and divided into four groups (n = 10): G1 (EIAE); G2 (XIAE); G3 (EDAE); G4 (XDAE) and G5 (control, IAE). The residues persistence using scores by SEM (500x). Fifty fragments were prepared similarly as described before and subjected to laser confocal microscopy (1024X). The hybrid layer formation was measured using Image J program. Fifty fragments were similarly prepared and submitted to microshear bond test to access the bond strength of etch-and-rinse ...(Complete abstract electronic access below) / Doutor

RESUMO O objetivo deste estudo foi comparar a citotoxicidade in vitro dos solventes utilizados em terapia de retratamento endodôntico: óleo de casca de laranja, eucaliptol, xilol, clorofórmio e halotano através da avaliação da citotoxicidade de cada solvente em diferentes concentrações finais e condições de contato com as células de fibroblastos de linhagem NIH 3T3. O experimento foi dividido em 4 etapas: etapa 1- os solventes foram misturados em meio de cultura (DMEM) nas concentrações finais de 0, 5, 10, 25, 50 e 100% e depositados sobre a cultura de células para o tempo de 5 minutos; etapa 2-os solventes foram misturados em meio de cultura nas concentrações finais de 0, 10 e 25% e depositados sobre a cultura de células para os tempos de 10 e 15 minutos; etapa 3a- os solventes foram depositados sobre as células de fibroblastos (contato direto) e acrescido de meio de cultura; etapa 3b-onde os fibroblastos receberam o meio de cultura e sobre este depositado os solventes testes (contato indireto) nas concentrações finais de 0, 5 e 10% para o tempo de 5 minutos; etapa 4- os solventes foram previamente solubilizados com o álcool absoluto na proporção de 1:1 e depois misturados ao meio de cultura na concentração final de 5% para o tempo de 5 minutos. A avaliação foi realizada pela contagem celular através de método de exclusão de células coradas pelo azul Trypan. Os resultados obtidos nos permitiram concluir que todos os solventes testados são citotóxicos in vitro, sendo que o óleo de laranja foi o menos tóxico, ao permitir alguma viabilidade celular. Observou-se ainda que o preparo prévio dos solventes influenciou no percentual de células viáveis. / SUMMARY The aim of this study was to compare in vitro solvents used in endodontic retreatment therapy: orange oil, eucalyptol, xylene, chloroform and halothane through cytotoxicity evaluation of each solvent in different final concentration and contact conditions to NIH 3T3 fibroblasts cells lines. The experiment was divided in four stages: stage 1- the solvents were mixed in culture medium (DMEM) in final concentrations of 0, 5, 10, 25, 50 and 100% placed on the cells in culture for periods of 5 minutes; stage 2- the solvents were mixed in culture medium in finals concentrations of 0, 10 and 25% placed on the cells in culture for periods of 10 and 15 minutes; stage 3a- the solvents were placed on the fibroblasts cells (direct contact) and added culture medium; stage 3b- the fibroblasts cells get first culture medium and after that solvents were placed (indirect contact), in bouth the finals concentrations were 0, 5 and 10% for periods of 5 minutes; stage 4- solvents were previously solubilized in absolut alcohol in 1:1 proportion and mixed in culture medium in 5% final concentration for periods of 5 minutes. The evaluation were achieved by cellular counting through dyed exclusion method-Trypan blue. The results showed that all solvents were toxic in vitro, and orange oil was less toxic and it allowed some cellular viability. And we could observe that a previous solvents preparation influenced in the viable cells percentage.

Hydrocracking of plastic wastes offers the best value in terms of quality of its process oil product among other feedstock recycling methods capable of recycling mixed plastic waste; a paraffin-rich synthetic crude similar in composition to gasoline and diesel is produced. Additional benefits of the process include heteroatom removal, catalyst conservation as well as a lower process temperature. However PVC content in mixed plastics waste and the high viscosity of plastics are prominent issues in relation to subjecting plastics to petrochemical processes such as hydrocracking. A 5ppm chlorine limit and maximum feedstock viscosity of 0.5 Pas at 200oC is tolerable in the petrochemical industry. Although dechlorination of mixed plastic waste has been studied exhaustively, viscosity studies in relation to process improvement or efficiency in the pyrolysis or hydrocracking of plastics haven’t received as much attention. Viscosity has been identified as being inhibitive to heat and mass transfer, and transport into reactors, as well as being a major problem in relation to designing reactors for feedstock recycling. In this research, four of the main polymer types; high-density polyethylene (HDPE), linear low-density polyethylene (LLDPE), Polypropylene (PP), Polystyrene (PS) and Polyethylene Terephthalate (PET) were rheological characterised to establish the extent to which they exceed the recommended viscosity in the petroleum industry. Viscosities 400 – 1200 times the feedstock viscosity in the petrochemical industry at a shear rate of 500s-1, which is typical for pumping and atomisation operations, were obtained during the characterisation of the plastic samples in a conventional capillary rheometer. Saturated chain hydrocarbon solvents (iso-octane, decane, tetradecane, pentadecane and hexadecane) were investigated for treating HDPE, in a range of HDPE-solvent mixtures, in order to reduce its viscosity. Preliminary results of differential scanning calorimetry tests carried out on the solvent-treated HDPE revealed a 12 – 16% drop in the melting peak temperature of the pure HDPE (129 oC) using tetradecane (108 oC), pentadecane (110 oC) and hexadecane (113 oC) for the 20:80 PE-solvent mixtures. iso-octane and decane however only produced a viscosity drop of 3% and 4% respectively for the same 20:80 PE-solvent mixtures. Thermal stability of HDPE was largely unaffected by the solvent treatment except in the case of pentadecane which showed a reducing trend on the decomposition onset temperature as solvent concentration in the starting mixtures was increased, albeit marginal (from 441oC to 437oC). A custom built sealed-vessel impeller viscometer designed to facilitate the treatment of the HDPE via solvent refluxing and in situ viscosity measurement was calibrated by determining constants which enable the conversion of machine data to viscosity and shear rate using Newtonian and non-Newtonian calibration fluids. These constants, the shape factor and shear rate conversion factor, were determined to be 81.03 and 22.08, respectively, with corresponding 95% confidence limits of 79.21 and 86.26, and 21.47 and 24.00. Viscosity measurements of a 40:60 PE-nC15 mixture carried out in the sealed-vessel impeller viscometer at a shear rate of between 71s-1 and 80s-1 at 95% confidence level and 250oC was 7 Pas representing approximately 200 fold reduction from the virgin HDPE measured in the conventional capillary rheometer.

The purpose of this thesis is to analyze the thermochemical properties of solutes in nonelectrolyte pure solvents and to develop mathematical expressions with the ability to describe and predict solution behavior using mobile order theory. Solubilities of pesticides (monuron, diuron, and hexachlorobenzene), polycyclic aromatic hydrocarbons (biphenyl, acenaphthene, and phenanthrene), and the organometallic ferrocene were studied in a wide array of solvents. Mobile order theory predictive equations were derived and percent average absolute deviations between experimental and calculated mole fraction solubilities for each solute were as follows: monuron in 21 non-alcoholic solvents (48.4%), diuron in 28 non-alcoholic solvents (60.1%), hexachlorobenzene (210%), biphenyl (13.0%), acenaphthene (37.8%), phenanthrene (41.3%), and ferrocene (107.8%). Solute descriptors using the Abraham solvation model were also calculated for monuron and diuron. Coefficients in the general solvation equation were known for all the solvents and solute descriptors calculated using multilinear regression techniques.