The purpose of this investigation was to determine the effect of the operating variables of type of reactor, catalyst, ethylene feed concentration, temperature, and contact time on the products of oxidation of ethylene to ethylene oxide; and together with subsequent hydrolysis to evaluate the commercial feasibility of the manufacture of ethylene glycol. The review of the literature contained 10 references. The equipment employed was arranged as indicated in a general flow diagram for the system. A silver catalyst activated by barium peroxide was employed and prepared on No.7 and No.3 Valencia pumice as the carrier according to Wiseman. For the analysis of ethylene oxide the procedure employed was a modification of that suggested by Vaughan and Wiseman. The carbon dioxide content of the product gases was determined by absorption of the carbon dioxide by ascarite; moisture was removed by means of drierite. Data and Results: A summation was made of operating conditions, yields and conversion in the air oxidation of ethylene in a fixed bed and fluidized bed reactor as a function of type of catalyst, contact time, reactor bath temperature, ethylene feed concentration, employing a barium peroxide activated silver catalyst coated on No.3 and No.7 Valencia pumice , uncoated pumice, and mixtures of these catalysts. It was found advisable to employ a 50% mixture of catalyst-coated and uncoated carrier in the tests because of the tendency toward fusion of the catalyst particles when used alone as the reactor charge . An increase the ethylene feed concentration from 3 to 9 per cent does not seem to appreciably affect either the conversion or yield. / Ph. D.

The research presented in this thesis includes a detailed investigation into factors influencing ionic conductivity in the crystalline polymer electrolyte PEO₆:LiPF₆. It has previously been shown that preparing PEO₆:LiPF₆ with PEO modified with larger –OC₂H₅ end groups increases ionic conductivity by one order of magnitude [¹],primarily due to disruption of the crystal structure caused by the inclusion of the larger end groups. In this study it is shown that by reducing PEO molecular weight in crystalline PEO₆:LiPF₆ ionic conductivity is also increased. This was attributed to an increasing concentration of polymer chain end regions upon lowering molecular weight resulting in the creation of more defects, as well as possible increases in crystallite size resulting in longer continuous pathways for ion transport. Similar results were observed using both polydispersed and monodispersed PEO to prepare complexes. In addition, it is demonstrated here that ionic conductivity in crystalline polymerelectrolytes is not confined to PEO₆:LiXF₆ (X=P, As, Sb)[²][³] type materials. The structures and ionic conductivity data are reported for a series of new crystalline polymer complexes: the alkali metal electrolytes. They are composed of low molecular weight PEO and different alkali metal hexafluoro salts (Na⁺, K⁺ and Rb⁺), and include the best conductor poly(ethylene oxide)₈:NaAsF₆ discovered to date [⁴], with a conductivity 1.5 orders of magnitude higher than poly(ethylene oxide)₆:LiAsF₆. A new class of solid ion conductor is reported: the crystalline small-molecule electrolytes. Such materials consist of lithium salts dissolved in low molecular weight glyme molecules [CH₃O(CH₂CH₂O)[subscript(n)]CH₃, n=1-12], forming crystalline complexes [⁵][⁶]. These materials are soft solids unlike ceramic electrolytes and unlike polymer electrolytes they are highly crystalline, are of low molecular weight and have no polydispersity. By varying the number of repeat units in the glyme molecule, many complexes may be prepared with a wide variety of structures. Here, ionic conductivity and cation transference number (t₊) data for several such complexes is presented [⁷][⁸][⁹].These complexes have appreciable ionic conductivities for crystalline complexes and their t₊ values vary markedly depending on the glyme molecule utilized. The differences in t₊ values can be directly attributed to differences in their crystal structures. [¹] Staunton, E., Andreev, Y.G. & Bruce, P.G. Factors influencing the conductivity of crystalline polymer electrolytes. Faraday Discussions 134, 143-156 (2007). [²] Gadjourova, Z., Andreev, Y.G., Tunstall, D.P. & Bruce, P.G. Ionic conductivity in crystalline polymer electrolytes. Nature 412, 6846 (2001). [³] Stoeva, Z., Martin-Litas, I., Staunton, I., Andreev, Y.G. & Bruce, B.G. Ionic Conductivity in the Crystalline Polymer Electrolytes PEO₆:LiXF₆, X = P, As, Sb. J. Am. Chem. Soc. 125, 4619-4626(2003). [⁴] Zhang, C., Gamble, S., Ainsworth, D., Slawin, A.M.Z., Andreev, Y.G. & Bruce, P.G. Alkali metal crystalline polymer electrolytes. Nature Materials 8, 580-584 (2009). [⁵] Henderson, W.A., Brooks, N.R., Brennessel, W.W. & Young Jr, V.G. Triglyme-Li⁺ Cation Solvate Structures: Models for Amorphous Concentrated Liquid and Polymer Electrolytes (I). Chem. Mater. 15, 4679-4684 (2003). [⁶] Henderson, W.A., Brooks, N.R. & Young Jr, V.G. Tetraglyme-Li⁺ Cation Solvate Structures: Models for Amorphous Concentrated Liquid and Polymer Electrolytes (II). Chem. Mater. 15, 4685-4690 (2003). [⁷] Zhang, C., Andreev, Y.G. & Bruce, P.G. Crystalline small-molecule electrolytes. Angewandte Chemie, International Edition 46, 2848-2850 (2007). [⁸] Zhang, C., Ainsworth, D., Andreev, Y.G. & Bruce, P.G. Ionic Conductivity in the Solid Glyme Complexes [CH₃O(CH₂CH₂O)[subscript(n)]CH₃]:LiAsF₆ (n = 3,4). J. Am. Chem. Soc. 129, 8700- 8701 (2007). [⁹] Zhang, C., Lilley, S.J., Ainsworth, D., Staunton, E., Andreev, Y.G., Slawin, A.M.Z. & Bruce, P.G. Structure and Conductivity of Small-Molecule Electrolytes [CH₃O(CH₂CH₂O)[subscript(n)]CH₃]:LiAsF₆ (n = 8-12). Chem. Mater. 20, 4039-4044 (2008).

The relaxation characteristics of rubbery poly(ethylene oxide) [PEO] networks have been investigated as a function of network composition and architecture via dynamic mechanical analysis and broadband dielectric spectroscopy. A series of model networks were prepared via UV photopolymerization using poly(ethylene glycol) diacrylate [PEGDA] as crosslinker: variations in crosslink density were achieved either by the introduction of water in the prepolymerization reaction mixture, or by the inclusion of mono-functional acrylate such as poly(ethylene glycol) methyl ether acrylate [PEGMEA] or poly(ethylene glycol) acrylate [PEGA]. Copolymerization with mono-functional acrylate led to the insertion of flexible branches along the network backbone, and the corresponding glass-rubber relaxation properties of the copolymers (i.e., Tg, relaxation breadth, fragility) were a sensitive function of network architecture and corresponding fractional free volume. Relatively subtle variations in network structure led to significant differences in relaxation characteristics, and a systematic series of studies was undertaken to examine the influence of branch length, branch end-group, and crosslinker flexibility on viscoelastic response. Dielectric spectroscopy was especially useful for the elucidation of localized, sub-glass relaxations in the polymer networks: the imposition of local constraint in the vicinity of the crosslink junctions led to the detection of a distinctive fast relaxation process in the networks that was similar to a comparable sub-glass relaxation observed in crystalline PEO and in the confined regions of PEO nanocomposites. Gas permeation studies on the model PEGDA networks confirmed their utility as highly-permeable, reverse-selective membrane materials, and strategic control of the network architecture could be used to optimize gas separation performance. Dynamic mechanical and dielectric measurements have also been performed on a semicrystalline polyester, poly(trimethylene terephthalate) [PTT], in order to assess the influence of processing history on the resultant morphology and corresponding viscoelastic relaxation characteristics. Studies on both quenched and annealed PTT revealed the presence of a substantial fraction of rigid amorphous phase (RAP) material in the crystalline samples: dielectric measurements showed a strong increase in relaxation intensity above the glass transition indicating a progressive mobilization of the rigid amorphous phase with increasing temperature prior to crystalline melting.

Ce travail porte sur l’étude de revêtements polysilazane (PSZ) élaborés dans le but d’inhiber l’adhésion des bactéries marines. Deux stratégies ont été étudiées : le greffage de chaînes poly(oxyde d’éthylène) (POE) (350, 750 ou 2000 g/mol) sur les chaînes PSZ par réactions d’hydrosilylation d’une part, et l’incorporation de composés du cuivre dans un film céramique issu de la pyrolyse d’un précurseur PSZ, d’autre part. Les conditions optimales de synthèse des PSZ greffés POE ont été définies afin de limiter notamment la réaction d’isomérisation de l’allyl-POE. La réticulation des PSZ greffés POE est alors effectuée par voie humide à température ambiante et procède par hydrolyse-condensation des fonctions alcoxysilane, SiH et SiN du précurseur PSZ. La prédominance des Si de type T3 (RSi(OSi)3) a été mise évidence par spectrométrie RMN du 29Si à l’état solide. La cristallisation des chaînes courtes de POE (350 g/mol) est totalement inhibée alors que l’aptitude des chaînes longues POE (750 et 2000 g/mol) à cristalliser est préservée. Le caractère hydrophile-hydrophobe et la capacité des films à inhiber l’adhésion bactérienne a été étudiée sur des revêtements à densités de greffons et à longueur de chaînes POE différentes. Les PSZs greffés POE 350g/mol avec un taux de greffage maximal conduisent à l’activité bactérienne la plus élevée de l’ensemble des revêtements étudiés.Les films céramiques incorporant du cuivre ont été préparés par pyrolyse d’un oligovinylsilazane en présence d’acétylacétonate de cuivre II sous atmosphère oxydante ou non oxydante. L’identification des phases des composés du cuivre a été effectuée par analyse DRX. L’environnement réducteur généré lors de la pyrolyse du PSZ favorise la formation d’espèces de cuivre (0) et cuivre (I) au détriment de cuivre (II). Les études bactériennes suggèrent que les cristaux CuO et Cu2O sont plus efficaces que le cuivre métal pour lutter contre l’adhésion bactérienne. / The objective of this work was to develop new polysilazane (PSZ) coatings which can inhibit the adhesion of marine bacteria. Two chemical strategies have been investigated: the grafting of poly(ethylene oxide) (POE) (350, 750, 2000 g/mol) on PSZ chains by hydrosilylation and the association of copper compounds with a pyrolized vinylsilazane matrix. The optimum conditions for grafting POE were defined to have a high selectivity toward olefin hydrosilylation. Crosslinking of POE-graft-PSZ was performed by moisture curing at room temperature. The main reactions occuring during curing are hydrolysis-condensation reactions of alkoxysilane, Si-H and Si-N functionalities. 29Si NMR in the solid state revealed the formation of a large amount of T3 Si [(RSi(OSi)3)]. The crystallization of short POE chains (350 g/mol) was found to be totally inhibited whereas long POE grafts (750 and 2000 g/mol) are still able to crystallize. The hydrophilic-hydrophobic properties and the antibactericidal activity of films with different graft density and POE chain length were studied. The POE (350 g/mol)-graft-PSZ with the greatest graft density were found to have the best antibactericidal activity. The incorporation of copper compounds in a pyrolized oligovinylsilazane was performed using copper acetylacetonate as a copper source. Pyrolysis was conducted in air or in Argon atmosphere. Identification of the copper phases was performed by XRD analysis. The reductive environment during thermal degradation of PSZ was found to favour the formation of copper (0) and copper (I) species relative to copper (II) species. The study of bacterial adhesion suggested that CuO and Cu2O crystals were more effective against bacterial adhesion than copper metal.

O principal propósito da enxertia óssea é estimular a osteogênese, mas é útil que o enxerto apresente outras propriedades tais como a resistência mecânica, possibilidade de estocagem e de ser usado em diferentes quantidades. Nesta pesquisa nós estudamos algumas propriedades mecânicas e o desempenho biológico de uma amostra de enxerto ósseo homógeno quimicamente processado e esterilizado em óxido de etileno. Primeiramente, amostras cilíndricas de tal enxerto, foram ensaiadas mecanicamente em compressão. Em uma segunda instância, o enxerto foi implantado em cães adultos. Trinta animais foram divididos em dois grupos. No grupo I, dez cães receberam um bloco cilíndrico de osso homógeno quimicamente preparado que foi implantado num leito cilíndrico confeccionado na epífise distal do fêmur direito. Três semanas após, o mesmo animal foi submetido à mesma cirurgia, desta vez no fêmur esquerdo. Seis semanas após a primeira operação, o cão foi sacrificado. O grupo II consistiu de vinte cães que receberam um enxerto autógeno cilíndrico que foi obtido do fêmur esquerdo e implantado no fêmur direito, da mesma forma que no grupo I. Dez animais (subgrupo A) foram sacrificados três semanas após o implante e dez animais (subgrupo B) foram sacrificados seis semanas após o implante. Os animais foram acompanhados clinicamente, e a integração do enxerto foi avaliada com raio-x obtidos seis dias após a operação e imediatamente após o sacrifício. Nossos resultados mostraram que o osso tratado mostrou menores valores para a Tensão, Deformação, e Módulo de Elasticidade, no limite elástico, quando comparado com o osso fresco. Os estudos radiográficos mostraram boa integração do enxerto tratado, entretanto, com menor desempenho quando comparado com o enxerto autógeno. O enxerto homógeno processado quimicamente e esterilizado em óxido de etileno, pode ser usado, como alternativa para o enxerto autógeno, tanto na medicina veterinária, quanto na medicina humana. / The main purpose of bone grafting is to stimulate osteogenisis but, sometimes, it is useful that the graft present other properties such as mechanical resistance, stocking, and possibility of being used in different amounts. In this investigation we studied some mechanical properties and the biological performance of a kind of a homogenous graft chemically prepared and sterilized in ethylene oxide. Previously, cylindrical samples of such graft were tested mechanically in compression. In a second instance, the graft was implanted in mature dogs. Thirty adults animals were divided into two groups. In group I, ten dogs received a cylindrical block of homogenous chemically prepared bone that was implanted in a cylindrical hollow created in distal epiphysis of the right femur. Three weeks later the same animal was operated on and the same operation was performed on the left femur. Six weeks after the first operation the dog was killed. The group II consisted of twenty dogs that received a cylindrical autologous graft that was harvested from the left femur and implanted in the right femur, as performed for group I. Ten animals (subgroup A) were killed tree weeks after the grafting operation and ten animals (subgroups B) were killed six weeks later. The animals were followed-up clinically and the graft integration was evaluated with x-ray taken six days after the operation and before the sacrifice. Ours results showed that the treated bone displayed smaller values for the tension, deformation and modulus of elasticity at yielding point, when compared with the fresh bone. The radiographic studies showed good integration of the treated graft, although with less performance when compared with the autologous graft. Homogenous graft, chemically prepared and sterilized in ethylene oxide, can be used as substitute to autologous graft both in veterinary and human medicine.

O desempenho de um processo de produção de óxido de etileno é normalmente avaliado através da seletividade da reação. Neste trabalho, uma unidade produtiva foi estudada com o objetivo de se maximizar a seletividade através da atuação sobre as principais variáveis de processo. Uma análise estatística de um conjunto de dados de processo mostrou que quatro variáveis (vazão de oxigênio, vazão de gás de reciclo, temperatura da reação e teor de clorados) são as de maior influência sobre a seletividade e explicam mais de 60% das variações ocorridas no processo produtivo. Com base nessa análise de dados, modelos de regressão multilinear foram desenvolvidos e testados com o objetivo de representar o comportamento do processo em função apenas do comportamento dessas quatro variáveis. O modelo matemático empírico proposto para representar esse processo foi validado estatisticamente e fenomenologicamente, demonstrando consistência com os dados obtidos em processo. O modelo também foi desdobrado em 24 submodelos que representam condições possíveis de operação da unidade e para os quais foram elaboradas superfícies de respostas que permitiram definir a melhor forma de gestão das 4 variáveis críticas conjuntamente, de modo a se obter a máxima seletividade possível para a reação em função desses cenários operacionais. / The performance of an ethylene oxide manufacturing process is normally measured by the selectivity reaction. In this work, a production unit was studied in order to maximize selectivity through the development of a strategic plan to main to manage the key process variables. A statistical analysis of a data set indicated that only four variables (oxygen flow, recycle gas flow, temperature reaction and chlorine content) are responsible for the greater influence over the selectivity and explain more than 60% of process variations. As consequence, regression models were developed and tested in order to represent the process behavior as a function of these four variables. The proposed mathematical model was statistically and phenomenologically validated, demonstrating consistency with the current process data. The model was rewritten in 24 sub-models, named deployed models which represent possible operational conditions of the unit. A set of surface responses was defined for each deployed model, providing to identify the best way for the management of these 4 critical variables. Furthermore, this analysis leads to a management tool for achieving the best results in selectivity, as function of the possible operational scenarios for this unit.

Considerando a importância da garantia de esterilidade em produtos médico-hospitalares, e conhecendo a necessidade de controle do processo esterilizante por óxido de etileno através de vários parâmetros dentre eles pelo sensor biológico, este trabalho teve como objetivo a padronização de alguns aspectos importantes do monitor biológico. Esporos de Bacillus subtilis var. niger foram obtidos em meios sólido e líquido sintético de esporulação, assim como adquiridos no comércio nacional, como suspensão. Seguiu-se a inoculação destes sobre suportes de papel, alumínio e plástico, com subsequente acondicionamento em embalagens protetoras, com o que se chegou à preparação dos indicadores biológicos. Foram testados, comparativamente, indicadores biológicos, em suporte de papel, adquiridos no comércio nacional e norte americano. As variáveis consideradas no preparo de monitores biológicos foram: natureza do suporte e da embalagem e dimensão de corpo de prova. Foram preparados 27 grupos de monitores biológicos, sendo 19 em suporte de papel, 4 em alumínio e 4 em plástico, constituindo assim 3 grupos múltiplos. A verificação da influência da natureza do suporte na resistência dos esporos foi através do processamento sub-letal de monitores biológicos, seguido de estudo de letalidade e cálculo dos valores de D. Com relação aos 19 grupos em suporte de papel, apesar da origem diferenciada dos esporos no tocante à fase de esporulação, seja quanto à natureza do meio de cultura, do ciclo ou do laboratório produtor, ou ainda dos bioindicadores de fabricantes distintos, não houve diferença estatisticamente significante na resistência dos esporos ao agente esterilizante. Houve diferença significativa na resistência dos esporos entre suportes de papel e plástico. Com relação à efetividade esterilizante do gás através de embalagens de natureza diferente foram testados monitores biológicos contendo bioindicadores em suporte de papel, após exposição dos mesmos ao ciclo sub-letal. Os valores de D obtidos evidenciaram a compatibilidade de diferentes embalagens com a esterilização por óxido de etileno, desde que respeitada a característica de porosidade. Num grupo adicional de monitores biológicos, utilizando papel como suporte em que a variável foi a dimensão dos corpos de prova o processo esterilizante foi por ciclo industrial seguido de recuperação dos esporos sobreviventes através de inoculação dos suportes em caldo tioglicolato, caldo caseina soja e este adicionado de azul de bromotimol. A capacidade promotora de crescimento destes 3 meios não apresentou diferenças. A eficácia esterilizante foi dependente do tamanho de corpos de prova. A determinação periódica do teor residual de gás nos corpos de prova, bem como a monitoração ambiental industrial indicaram a necessidade e importância da legislação em vigor, devendo haver plena obediência à mesma. / This study intended to standardize some of the important elements of biological indicators, taken in consideration the importance of sterility assurance of medical devices and knowing the necessity of Ethilene Oxide sterilization process control throught several parameters, among them the biological sensor. Spores of Bacillus .subtilis var. niger, were produced in chemically defined liquid and solid sporulation media, as well as purchased as suspension from local suppliers. The biological indicators were obtained after being inoculated on paper, aluminum foil and plastic carriers following by wrapping on protective packaging. In parallel biological indicators in paper carriers, purchased from local market and from United States suppliers were also tested. The variables considered on preparation of the biological monitors were: the nature of the carriers and packages used and the dimension of the test specimens. Twenty seven individual groups of biological monitors have been prepared, being 19 on paper carrier, 4 into aluminum foil and 4 into plastic, bringing to 3 multiple groups. The evaluation of the nature of the carrier on the spore resistance was done through the challange of the biological monitors to sub-lethal cycles, followed by lethality study and D value calculation. Within the 19 groups on paper carrier no significant statistical difference was observed in respect to spores resistance to the sterilization agent, in spite of the various sources of the spores, with respect to the sporulation stage, no matter the nature of culture media, the cycle or the generating laboratory, or even bioindicators from distinct manufacturers. There was an significant statistical difference on spores resistance between paper and plastic carriers. In respect to the gas sterilization effectiveness across packages of different nature, biological monitors were tested containing bioindicators in paper carriers, after their exposure to sub-lethal cycles. The D values obtained made patent the compatibility of distinct packages to ethilene oxide sterilization provided the porosity caracteristics are respected. In an additional group of biological, monitors, using paper as carrier and on that the dimension of the test specimens was the variable considered the sterilization process was an industrial cycle, followed by a surviving spores recovery through the carriers inoculation into thioglicolate broth, soybean-casein broth and also the last broth added with bromothymol blue. The growing promoting capacity of those 3 media did not show differences. The sterilization effectiveness was dependent to the dimension of the test specimens. The periodic determination of residual gas content on the test specimens, as well as the industrial environment monitoring denote the need and importance of the legislation in force, being imperative full compliance to the same.

Considerando a importância da garantia de esterilidade em produtos médico-hospitalares, e conhecendo a necessidade de controle do processo esterilizante por óxido de etileno através de vários parâmetros dentre eles pelo sensor biológico, este trabalho teve como objetivo a padronização de alguns aspectos importantes do monitor biológico. Esporos de Bacillus subtilis var. niger foram obtidos em meios sólido e líquido sintético de esporulação, assim como adquiridos no comércio nacional, como suspensão. Seguiu-se a inoculação destes sobre suportes de papel, alumínio e plástico, com subsequente acondicionamento em embalagens protetoras, com o que se chegou à preparação dos indicadores biológicos. Foram testados, comparativamente, indicadores biológicos, em suporte de papel, adquiridos no comércio nacional e norte americano. As variáveis consideradas no preparo de monitores biológicos foram: natureza do suporte e da embalagem e dimensão de corpo de prova. Foram preparados 27 grupos de monitores biológicos, sendo 19 em suporte de papel, 4 em alumínio e 4 em plástico, constituindo assim 3 grupos múltiplos. A verificação da influência da natureza do suporte na resistência dos esporos foi através do processamento sub-letal de monitores biológicos, seguido de estudo de letalidade e cálculo dos valores de D. Com relação aos 19 grupos em suporte de papel, apesar da origem diferenciada dos esporos no tocante à fase de esporulação, seja quanto à natureza do meio de cultura, do ciclo ou do laboratório produtor, ou ainda dos bioindicadores de fabricantes distintos, não houve diferença estatisticamente significante na resistência dos esporos ao agente esterilizante. Houve diferença significativa na resistência dos esporos entre suportes de papel e plástico. Com relação à efetividade esterilizante do gás através de embalagens de natureza diferente foram testados monitores biológicos contendo bioindicadores em suporte de papel, após exposição dos mesmos ao ciclo sub-letal. Os valores de D obtidos evidenciaram a compatibilidade de diferentes embalagens com a esterilização por óxido de etileno, desde que respeitada a característica de porosidade. Num grupo adicional de monitores biológicos, utilizando papel como suporte em que a variável foi a dimensão dos corpos de prova o processo esterilizante foi por ciclo industrial seguido de recuperação dos esporos sobreviventes através de inoculação dos suportes em caldo tioglicolato, caldo caseina soja e este adicionado de azul de bromotimol. A capacidade promotora de crescimento destes 3 meios não apresentou diferenças. A eficácia esterilizante foi dependente do tamanho de corpos de prova. A determinação periódica do teor residual de gás nos corpos de prova, bem como a monitoração ambiental industrial indicaram a necessidade e importância da legislação em vigor, devendo haver plena obediência à mesma. / This study intended to standardize some of the important elements of biological indicators, taken in consideration the importance of sterility assurance of medical devices and knowing the necessity of Ethilene Oxide sterilization process control throught several parameters, among them the biological sensor. Spores of Bacillus .subtilis var. niger, were produced in chemically defined liquid and solid sporulation media, as well as purchased as suspension from local suppliers. The biological indicators were obtained after being inoculated on paper, aluminum foil and plastic carriers following by wrapping on protective packaging. In parallel biological indicators in paper carriers, purchased from local market and from United States suppliers were also tested. The variables considered on preparation of the biological monitors were: the nature of the carriers and packages used and the dimension of the test specimens. Twenty seven individual groups of biological monitors have been prepared, being 19 on paper carrier, 4 into aluminum foil and 4 into plastic, bringing to 3 multiple groups. The evaluation of the nature of the carrier on the spore resistance was done through the challange of the biological monitors to sub-lethal cycles, followed by lethality study and D value calculation. Within the 19 groups on paper carrier no significant statistical difference was observed in respect to spores resistance to the sterilization agent, in spite of the various sources of the spores, with respect to the sporulation stage, no matter the nature of culture media, the cycle or the generating laboratory, or even bioindicators from distinct manufacturers. There was an significant statistical difference on spores resistance between paper and plastic carriers. In respect to the gas sterilization effectiveness across packages of different nature, biological monitors were tested containing bioindicators in paper carriers, after their exposure to sub-lethal cycles. The D values obtained made patent the compatibility of distinct packages to ethilene oxide sterilization provided the porosity caracteristics are respected. In an additional group of biological, monitors, using paper as carrier and on that the dimension of the test specimens was the variable considered the sterilization process was an industrial cycle, followed by a surviving spores recovery through the carriers inoculation into thioglicolate broth, soybean-casein broth and also the last broth added with bromothymol blue. The growing promoting capacity of those 3 media did not show differences. The sterilization effectiveness was dependent to the dimension of the test specimens. The periodic determination of residual gas content on the test specimens, as well as the industrial environment monitoring denote the need and importance of the legislation in force, being imperative full compliance to the same.

A series of pyrene end-labeled monodisperse poly(ethylene oxide)s (PEO(X)-Py2 where X represents the number average molecular weight (Mn) of the PEOs and equals 2, 5, 10 and 16.5 K) and one pyrene mono-labeled PEO (PEO(2K)-Py1) were synthesized and characterized in solution using fluorescence. First, the end-to-end cyclization (EEC) of PEO(X)-Py2 was investigated in seven organic solvents with viscosities (η) ranging from 0.32 to 1.92 mPa•s. The classical Birks scheme was used to globally fit the pyrene monomer and excimer fluorescence decays. The fraction of pyrenes that did not form excimer (ffree) was found to increase with increasing η and Mn. This result was contrary to the assumptions made by Birks’ scheme. To account for this, ffree was assumed to represent the fraction of PEO chains other than the monolabeled polymer impurities that cannot accomplish EEC. A fluorescence blob model (FBM) was applied to handle this assumption in the process of excimer formation for the PEO(X)-Py2 samples in solution. The radius of a blob, Rblob, in organic solvents was determined according to the results retrieved from the FBM. To quantitatively account for the existence of pyrene impurity in pyrene-labeled macromolecules, known amounts of PEO(2K)-Py1 were added into a PEO(2K)-Py2 solution and the fluorescence decays were fitted globally according to the Birks scheme and “model free” (MF) analysis to verify the validation of the MF analysis. The MF analysis was then applied to determine the amounts of 1-pyrenebutyric acid (PyBA) that had been added to a solution of pyrene end-labeled fourth generation dendritic hybrid (Py16-G4-PS). The results demonstrated that the contribution from unwanted fluorescent species could be isolated and quantitatively accounted for by fitting the fluorescence decays of the pyrene monomer and excimer globally with the MF analysis. Since the PEO(X)-Py2 samples form hydrophobic pyrene aggregates in aqueous solution, a sequential model (SM) was proposed to characterize the pyrene excimer formation of PEO(X)-Py2 in water at different polymer concentration (CP). The capture distance over which the pyrenyl end-groups experience hydrophobic forces in water was determined by assuming that the end-to-end distances of the PEO(X)-Py2 samples adopt a Gaussian distribution and that the fraction of pyrenes that are aggregated (fE0) determined by the sequential model corresponds to the fraction of PEO(X)-Py2 chains whose end-to-end distance is smaller than the hydrophobic capture distance. Since a surfactant can interact with a hydrophobically modified water-soluble polymer in aqueous solution, the interactions taking place between PEO(X)-Py2 and sodium dodecyl sulfate (SDS) were investigated at a low PEO(X)-Py2 concentration. The pyrene monomer and excimer fluorescence decays of the PEO(X)-Py2 and SDS solutions were acquired at various SDS concentrations and globally fitted according to the MF analysis to retrieve the parameters that described the kinetics of pyrene excimer formation. At high SDS concentrations above the critical micelle concentration (CMC), the pyrene end-groups of the short-chain samples (PEO(2K)-Py2 and PEO(5K)-Py2) were incorporated inside the same micelle and excimer was formed intramolecularly, while most pyrene groups of the long-chain samples (PEO(10K)-Py2 and PEO(16.5K)-Py2) were isolated into different micelles. Lastly, both the rheological properties and fluorescence behavior of a pyrene-labeled hydrophobically-modified alkali-swellable emulsion (Py-HASE) polymer in basic aqueous solution with SDS were studied. Furthermore, a joint experimental setup that combined a rheometer and a steady-state fluorometer was applied to investigate at the molecular level the effect that a shearing force had on the polymeric network. However, despite the dramatic decrease in solution viscosity with increasing shear rate, no change in the fluorescence spectra was detected, suggesting that changes in the polymeric network that affected the balance of intra- versus intermolecular pyrene associations did not impact the process of excimer formation. Together the experiments described in this thesis represent the broadest set of examples found in the scientific literature where information on the dynamics and level of association of pyrene-labeled polymers has been retrieved through the quantitative analysis of the fluorescence decays acquired with pyrene-labeled polymers in solution.

This work computationally investigates the partial oxidation of ethylene (i.e. ethylene epoxidation) using periodic Density Functional Theory (DFT) on slab models that represent the catalyst surfaces. The mechanical aspects of the reaction were investigated on silver surfaces, which are industrially applied catalysts, for a wide range of surface models varying from metallic surfaces with low oxygen coverage to oxide surfaces. For comparison, the metallic and oxide phases of copper and gold were also studied. On these surfaces, the reaction paths and the transition states along these paths for the selective and non-selective reaction channels were obtained using the climbing image nudged elastic band (CI-NEB) method. In order to answer the question &ldquo / what is the relation between the surface state and the ethylene oxide selectivity?&rdquo / metallic (100), (110) and (111) surfaces of Cu, Ag and Au / and, (001) surfaces of Cu2O, Ag2O and Au2O oxides were studied and compared. For the studied metallic surfaces, it was found that the selective and non-selective reaction channels proceed through the oxametallacycle (OMC) intermediate, and the product selectivity depends on the relative barriers of the these channels, in agreement with the previous reports. However for the studied metallic surfaces and oxygen coverages, a surface state that favors the ethylene oxide (EO) formation was not identified. The studied Au surfaces did not favor the oxygen adsorption and dissociation, and the Cu surfaces favored the non-selective product (acetaldehyde, AA) formation. Nevertheless, the results of Ag surfaces are in agreement with the ~50% EO selectivity of the un-promoted silver catalyst. The catalyst surface in the oxide state was modeled by the (001) surfaces of the well defined Cu2O, Ag2O and Au2O oxide phases. Among these three oxides, the Cu2O is found not to favor EO formation whereas Au2O is known to be unstable, however selective for epoxidation. The major finding of this work is the identification of a direct epoxidation path that is enabled by the reaction of the surface oxygen atoms, which are in two-fold (i.e. bridge) positions and naturally exist on (001) oxide surfaces of the studied metals. Among the three oxides studied, only Ag2O(001) surface does not show a barrier for the formation of adsorbed epoxide along the direct epoxidation path. Moreover, the overall heat of reaction that is around 105 kJ/mol agrees well with the previous reports. The single step, direct epoxidation path is a key step in explaining the high EO selectivities observed. Also for the oxide surfaces, the un-selective reaction that ends up in combustion products is found to proceed through the OMC mechanism where aldehyde formation is favored. Another major finding of this study is that, for the studied oxide surfaces two different types of OMC intermediates are possible. The first possibility is the formation of the OMC intermediate on oxygen vacant sites, where the ethylene can interact with the surface metal atoms directly. The second possibility is the formation of a direct OMC intermediate, through the interaction of the gas phase ethylene with the non-vacant oxide surface. This occurs through the local surface reconstruction induced by the ethylene. The effect of Cl promotion was also studied. Coadsorption of Cl is found to suppress the oxygen vacant sites and also the reconstruction effects that are induced by ethylene adsorption. Thus, by preventing the interaction of the ethylene directly with the surface metal atoms, Cl prevents the OMC formation, therefore the non-selective channel. At the same time Cl increases the electrophilicity of reacting surface oxygen. The direct epoxidation path appears to be stabilized by coadsorbed oxygen atoms. Thus, we carry the discussions on the silver catalyzed ethylene epoxidation one step further. Herein we present that the EO selectivity will be limited in the case of metallic catalyst, whereas, the oxide surfaces enable a direct mechanism where EO is produced selectively. The role of the Cl promoter is found to be mainly steric where it blocks the sites of non-selective channel.