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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Association supramoléculaire à l'état solide des fullerènes C60 et C70 avec le centrohexaindane

Lachapelle, Virginie 09 1900 (has links)
Le fullerène C60, une molécule sphérique, et le C70, un analogue ellisoïde, sont des composés aromatiques convexes constitués exclusivement d'atomes de carbone. La nature aromatique de la surface de ces cages de carbone rend possible leur association à l'état solide avec d'autres molécules aromatiques de topologie complémentaire. En particulier, l'association des fullerènes avec des composés présentant des motifs concaves aromatiques, via une association de type concave-convexe, est favorable. En effet, les interactions π•••π de type concave-convexe sont amplifiées grâce à la complémentarité topologique des partenaires impliqués. Le centrohexaindane est un hydrocarbure non planaire rigide qui a été synthétisé pour la première fois en 1988 par Kuck et collaborateurs. Cette molécule possède quatre surfaces aromatiques concaves orientées dans une géométrie tétraédrique qui sont susceptibles d'interagir favorablement avec les fullerènes. Nous avons ainsi avec succès cocristallisé le centrohexaindane avec les fullerènes C60 et C70. Puis, nous avons étudié les assemblages à l'état solide entre le centrohexaindane et les fullerènes par l'analyse des structures résolues via diffraction des rayons X. Les surfaces concaves aromatiques du centrohexaindane se sont révélées être propices à une association avec les fullerènes C60 et C70 via des interactions π•••π de type concave-convexe, tel que prévu. En outre, nous avons découvert que les liaisons C-H situées à la périphérie du centrohexaindane prennent part à une multitude de contacts C-H•••π avec les molécules de fullerène. Les échantillons de cocristaux composés de centrohexaindane et de fullerène ont aussi été caractérisés par diffraction de poudre des rayons X et par analyse thermogravimétrique dans le but d'en évaluer l'homogénéité. / Spherical fullerene C60 and C70, its ellipsoidal analogue, are convex aromatic compounds consisting exclusively of carbon atoms. The aromatic nature of the surface of these carbon cages enables their solid-state association with aromatic molecules that have complementary shapes. In particular, the association of fullerenes with compounds that have concave aromatic units, by a concave-convex type of association, is favored. Indeed, concave-convex π•••π interactions are enhanced because of the topological complementarity of the partners. Centrohexaindane is a rigid nonplanar hydrocardon that was first synthesized in 1988 by Kuck and coworkers. It contains four concave aromatic surfaces, oriented in a tetrahedral geometry, that are likely to interact favorably with fullerenes. To study this phenomenon, we successfully cocrystallized centrohexaindane with fullerenes C60 and C70. We then resolved the structure of the resulting solid-state assemblies by X-ray diffraction. The concave aromatic surfaces of centrohexaindane proved to be conducive for an association with fullerenes involving concave-convex π•••π interactions, as expected. In addition, we found that C-H bonds located at the periphery of centrohexaindane participate in a variety of C-H•••π contacts with the fullerene partners. Samples of cocrystals containing centrohexaindane and fullerene were also characterized using powder X-ray diffraction and thermogravimetric analysis in order to assess their homogeneity.
22

Association supramoléculaire à l'état solide des fullerènes C60 et C70 avec le centrohexaindane

Lachapelle, Virginie 09 1900 (has links)
Le fullerène C60, une molécule sphérique, et le C70, un analogue ellisoïde, sont des composés aromatiques convexes constitués exclusivement d'atomes de carbone. La nature aromatique de la surface de ces cages de carbone rend possible leur association à l'état solide avec d'autres molécules aromatiques de topologie complémentaire. En particulier, l'association des fullerènes avec des composés présentant des motifs concaves aromatiques, via une association de type concave-convexe, est favorable. En effet, les interactions π•••π de type concave-convexe sont amplifiées grâce à la complémentarité topologique des partenaires impliqués. Le centrohexaindane est un hydrocarbure non planaire rigide qui a été synthétisé pour la première fois en 1988 par Kuck et collaborateurs. Cette molécule possède quatre surfaces aromatiques concaves orientées dans une géométrie tétraédrique qui sont susceptibles d'interagir favorablement avec les fullerènes. Nous avons ainsi avec succès cocristallisé le centrohexaindane avec les fullerènes C60 et C70. Puis, nous avons étudié les assemblages à l'état solide entre le centrohexaindane et les fullerènes par l'analyse des structures résolues via diffraction des rayons X. Les surfaces concaves aromatiques du centrohexaindane se sont révélées être propices à une association avec les fullerènes C60 et C70 via des interactions π•••π de type concave-convexe, tel que prévu. En outre, nous avons découvert que les liaisons C-H situées à la périphérie du centrohexaindane prennent part à une multitude de contacts C-H•••π avec les molécules de fullerène. Les échantillons de cocristaux composés de centrohexaindane et de fullerène ont aussi été caractérisés par diffraction de poudre des rayons X et par analyse thermogravimétrique dans le but d'en évaluer l'homogénéité. / Spherical fullerene C60 and C70, its ellipsoidal analogue, are convex aromatic compounds consisting exclusively of carbon atoms. The aromatic nature of the surface of these carbon cages enables their solid-state association with aromatic molecules that have complementary shapes. In particular, the association of fullerenes with compounds that have concave aromatic units, by a concave-convex type of association, is favored. Indeed, concave-convex π•••π interactions are enhanced because of the topological complementarity of the partners. Centrohexaindane is a rigid nonplanar hydrocardon that was first synthesized in 1988 by Kuck and coworkers. It contains four concave aromatic surfaces, oriented in a tetrahedral geometry, that are likely to interact favorably with fullerenes. To study this phenomenon, we successfully cocrystallized centrohexaindane with fullerenes C60 and C70. We then resolved the structure of the resulting solid-state assemblies by X-ray diffraction. The concave aromatic surfaces of centrohexaindane proved to be conducive for an association with fullerenes involving concave-convex π•••π interactions, as expected. In addition, we found that C-H bonds located at the periphery of centrohexaindane participate in a variety of C-H•••π contacts with the fullerene partners. Samples of cocrystals containing centrohexaindane and fullerene were also characterized using powder X-ray diffraction and thermogravimetric analysis in order to assess their homogeneity.
23

Stability of sodium sulfate dicarbonate (~2Na₂CO₃• Na₂SO₄) crystals

Bayuadri, Cosmas 23 May 2006 (has links)
Research on salts species formed by evaporation of aqueous solution of Na2 in the early 1930s. The thermodynamic, crystallographic and many other physical and chemical properties of most of the species formed from this solution has been known for decades. However, there was no complete information or reliable data to confirm the existence of a unique double salt that is rich in sodium carbonate, up until five years ago when a research identified the double salt (~2Na ₂ CO ₃ • Na ₂ SO ₄) from the ternary system Na₂CO ₃Na₂SO ₄ H₂O. Crystallization of this double salt so called sodium sulfate dicarbonate (~2Na ₂ CO ₃ • Na ₂ SO ₄) is known to be a primary contributor to fouling heat transfer equipment in spent-liquor concentrators used in the pulp and paper industry. Therefore, understanding the conditions leading to formation of this double salt is crucial to the elimination or reduction of an industrial scaling problem. In this work, double salts were generated in a batch crystallizer at close to industrial process conditions. X-ray diffraction, calorimetry, and microscopic observation were used to investigate the stability of the salts to in-process aging, isolation and storage, and exposure to high temperature. The results show that care must be taken during sampling on evaporative crystallization. Two apparent crystal habits were detected in the formation of sodium sulfate dicarbonate; the favored habit may be determined by calcium ion impurities in the system. The results also verify that sodium sulfate dicarbonate exists as a unique phase in this system and that remains stable at process conditions of 115-200℃
24

Mechanistic insights into the stabilisation of biopharmaceuticals using glycine derivatives : the effect of glycine derivatives on the crystallisation, physical properties and behaviour of commonly used excipients to stabilise antigens, adjuvants and proteins in the solid state

Bright, Andrew G. January 2015 (has links)
This dissertation has focused on studying the effect of four glycine derivatives on the solid state properties of mannitol, glycine, and sucrose when freeze dried into blended mixtures. The primary goal was to assess their value for use in the stabilisation of vaccines in the solid state, by examining key physical and chemical characteristics, which have been documented to be beneficial to the stabilisation of biopharmaceutical formulations. The novel excipients; dimethyl glycine, and trimethyl glycine, were shown to retard the crystallisation and increase the overall glass transition temperature, of mannitol, when freeze dried as evidenced by DSC and Powder X-ray diffraction. Mannitol’s glass transition temperature increased from 100C to 12.650C and 13.610C when mixed with methyl-glycine and dimethyl glycine respectively. The glycine derivatives did not show the same effect on sucrose which remained amorphous regardless of the concentration of the other excipient. The different behaviour with the sucrose system was thought to be due to relatively high glass transition temperature of sucrose. Conversely glycine remained highly crystalline due it’s relatively low glass transition temperature. The novel excipient formulations were also assessed for their effect on the aggregation of the adjuvant aluminium hydroxide when freeze dried by Dynamic Light Scattering (DLS).The formulations containing the glycine derivatives all caused a decrease in the aggregation size of the adjuvant from ~26 μm, to 185 nm in the presence of methyl glycine. The effects of lysozyme and viral antigen on the adjuvants were also examined showing that the addition of the virus did not affect the size of the aggregates formed, however lysozyme showed significant decreases in the aggregates formed. Examination of the freezing method were also made showing that faster freezing rates produced smaller aggregates of the adjuvant. When investigating the rate at which the excipients lost water during secondary drying there was evidence of the formation of hydrates of glycine, trimethyl glycine, and mannitol has shown that the glycine derivatives have attributes which would be beneficial in stabilising vaccines in the solid state when freeze dried.
25

Mechanistic Insights into the Stabilisation of Biopharmaceuticals using Glycine Derivatives. The Effect of Glycine Derivatives on the Crystallisation, Physical Properties and Behaviour of Commonly used Excipients to Stabilise Antigens, Adjuvants and Proteins in the Solid State

Bright, Andrew G. January 2015 (has links)
This dissertation has focused on studying the effect of four glycine derivatives on the solid state properties of mannitol, glycine, and sucrose when freeze dried into blended mixtures. The primary goal was to assess their value for use in the stabilisation of vaccines in the solid state, by examining key physical and chemical characteristics, which have been documented to be beneficial to the stabilisation of biopharmaceutical formulations. The novel excipients; dimethyl glycine, and trimethyl glycine, were shown to retard the crystallisation and increase the overall glass transition temperature, of mannitol, when freeze dried as evidenced by DSC and Powder X-ray diffraction. Mannitol’s glass transition temperature increased from 100C to 12.650C and 13.610C when mixed with methyl-glycine and dimethyl glycine respectively. The glycine derivatives did not show the same effect on sucrose which remained amorphous regardless of the concentration of the other excipient. The different behaviour with the sucrose system was thought to be due to relatively high glass transition temperature of sucrose. Conversely glycine remained highly crystalline due it’s relatively low glass transition temperature. The novel excipient formulations were also assessed for their effect on the aggregation of the adjuvant aluminium hydroxide when freeze dried by Dynamic Light Scattering (DLS).The formulations containing the glycine derivatives all caused a decrease in the aggregation size of the adjuvant from ~26 μm, to 185 nm in the presence of methyl glycine. The effects of lysozyme and viral antigen on the adjuvants were also examined showing that the addition of the virus did not affect the size of the aggregates formed, however lysozyme showed significant decreases in the aggregates formed. Examination of the freezing method were also made showing that faster freezing rates produced smaller aggregates of the adjuvant. When investigating the rate at which the excipients lost water during secondary drying there was evidence of the formation of hydrates of glycine, trimethyl glycine, and mannitol has shown that the glycine derivatives have attributes which would be beneficial in stabilising vaccines in the solid state when freeze dried. / Stabilitech Ltd. and the Engineering and Physical Sciences Research Council (EPSRC).

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