Role of Caustic Addition in Bitumen-Clay Interactions

Coating of bitumen by clays, known as slime coating, is detrimental to bitumen recovery from oil sands using the warm slurry extn. process. Sodium hydroxide (caustic) is added to the extn. process to balance many competing processing challenges, which include undesirable slime coating. The current research aims at understanding the role of caustic addn. in controlling interactions of bitumen with various types of model clays. The interaction potential was studied by quartz crystal microbalance with dissipation monitoring (QCM-D). After confirming the slime coating potential of montmorillonite clays on bitumen in the presence of calcium ions, the interaction of kaolinite and illite with bitumen was studied. To represent more closely the industrial applications, tailings water from bitumen extn. tests at different caustic dosage was used. At caustic dosage up to 0.5 wt % oil sands ore, a negligible coating of kaolinite on the bitumen was detd. However, at a lower level of caustic addn., illite was shown to attach to the bitumen, with the interaction potential decreasing with increasing caustic dosage. Increasing concn. of humic acids as a result of increasing caustic dosage was identified to limit the interaction potential of illite with bitumen. This fundamental study clearly shows that the crit. role of caustics in modulating interactions of clays with bitumen depends upon the type of clays. Thus, clay type was identified as a key operational variable

Elaboration de Nouveaux Matériaux d'Electrodes obtenus par Autoassemblage de Polyélectrolytes, Nanoparticules et Biomolécules : Etudes physico-chimiques et applications.

The thesis describes the physico-chemical characterization and the electroanalytical applications of new nanocomposite materials, built onto electrode surfaces, in the form of multilayer thin films, by electrostatic self-assembly of polyelectrolytes (PE), enzymes and gold nanoparticles (NP).The growth of these films was followed in situ by UV-Visible spectroscopy and microgravimetry. The electrochemistry allowed quantifying the electron transfer process, the films permability and the electroenzymatical kinetics. The kinetic and structural modelization allowed establishing structure-properties relationships.The glucose oxidase and the polyphenol oxidase have been assembled onto gold and glassy carbon electrodes with the polydiallyldimethylammonium and the chitosane. The assembly of NP with osmium complex or viologen based redox PE leads to nanocomposite films where the electronic conduction properties have been characterized and applied to the development of transducers.La thèse décrit la caractérisation physico-chimique et les applications électroanalytiques de nouveaux matériaux nanocomposites, déposés sur des surfaces d'électrode par autoassemblage électrostatique de polyélectrolytes (PE), d'enzymes et de nanoparticules d'or (NP).La croissance de ces films multicouches fut suivie in situ par spectroscopie et microgravimétrie. L'électrochimie a permis de quantifier le processus de transfert d'électron, la perméabilité des films et la cinétique électroenzymatique. Des relations structure-propriétés furent établies par modélisation cinétique et structurale.La glucose oxydase et la polyphénol oxydase furent assemblées sur des électrodes d'or et de carbone vitreux avec le polydiallyldimethylammonium et le chitosane. L'assemblage de NP et de PE redox, à base de complexe d'osmium ou de viologène, conduit à des films nanocomposites dont les propriétés de conduction électronique furent caractérisées et appliquées au développement de transducteurs

Real-time Microgravimetric quantification of Cryptosporidium parvum in the presence of potential interferents

The quartz crystal microbalance with dissipation monitoring (QCM-D) is used to develop a biosensor for detection of viable Cryptosporidium parvum (C. parvum) in water matrices of varying complexity. In a clean environment, a good log–log linear response is obtained for detection of C. parvum in aqueous suspensions with oocyst concentrations from 3 × 105 to 1 × 107 oocysts/mL. C. parvum detection is slightly affected by the presence of dissolved organic acids, likely due to steric stabilization and/or masking of the antibodies/antigens by adsorbed molecules. Colloidal contaminants generally have a greater influence as biosensor interferents, whereby the presence of model latex microspheres, Enterococcus faecalis, or Escherichia coli, led to decreases in biosensor response of up to 64%, 40%, and 20%, respectively

Influence diagram of physiological and environmental factors affecting heart rate variability: an extended literature overview

Heart rate variability (HRV) corresponds to the adaptation of the heart to any stimulus. In fact, among the pathologies affecting HRV the most, there are the cardiovascular diseases and depressive disorders, which are associated with high medical cost in Western societies. Consequently, HRV is now widely used as an index of health.In order to better understand how this adaptation takes place, it is necessary to examine which factors directly influence HRV, whether they have a physiological or environmental origin. The primary objective of this research is therefore to conduct a literature review in order to get a comprehensive overview of the subject.The system of these factors affecting HRV can be divided into the following five categories: physiological and pathological factors, environmental factors, lifestyle factors, non-modifiable factors and effects. The direct interrelationships between these factors and HRV can be regrouped into an influence diagram. This diagram can therefore serve as a basis to improve daily clinical practice as well as help design even more precise research protocols

Groundwater Pollution: Impacts on Human Health Fate and transport of microbial contaminants (MS number 40)

Microbial contamination of groundwater by viruses, bacteria and parasitic protozoa is a significant human health problem when drinking water supplies are untreated or inadequately treated. The decision to treat groundwater supplies. If sufficient resources are available, often depends upon the adequacy of pathogen and/or indicator organism attenuation in the subsurface. Microbial fate and transport processes govern attenuation in the subsurface. Hence, a thorough understanding of the mechanism and factors affecting the fate and support of microbial contaminants in the subsurface environment is essential for the protection of public health from waterborne disease. [...] Microbial transport is mainly controlled by advection whereas the key processes governing the fate of microorganisms are retention onto aquifer solid surfaces and inactivation (or survival) of the microbes. Groundwater chemistry and moisture content are identified as two of the main physiochemical factors that influence the retention and survival of microorganisms in the subsurface. Finally, the importance of linking this fundamental science to the development of appropriate public policy and land use strategy is highlighted

Real-time QCM-D monitoring of cellular responses to different cytomorphic agents.

Quartz crystal microbalance with dissipation monitoring (QCM-D) is used for real-time in situ detection of cytoskeletal changes in live primary endothelial cells in response to different cytomorphic agents; namely, the surfactant Triton-X 100 (TX-100) and bacterial lipopolysaccharide (LPS). Reproducible dissipation versus frequency (Df) plots provide unique signatures of the interactions between endothelial cells and cytomorphic agents. While the QCM-D response for TX-100 can be described in two steps (changes in the osmotic pressure of the medium prior to observing the expected cell lysis), LPS results in a different single-phase signal. […] Observations obtained by QCM-D signals are confirmed by conducting fluorescence microscopy at the same time. Our results show that a fast (few minutes) sensing response can be obtained in situ and in real-time. The conclusions from this study suggest that QCM-D can potentially be used in biodetection for applications in drug screening tests and diagnosis

From Serious Shortage of Researchers to OHS Law Changes and Growing Industrial Needs : A Dynamic and Quiet Force

Scientists having raised concerns about technological advancements and the associated risks, the Quebec scientific community implemented the work safety component within the Quebec Occupational Health and Safety Research Network (QOHSRN). This initially fostered a first geographical connection among scientists, thus facilitating knowledge exchange and transfer. With various research themes, the first component members made an initial observation of the critical situation in regard to occupational safety in the industrial sector. Yet, occupational safety is a shared concern affecting all industrial sectors, environments and countries. The strategic occupational safety component expanded its efforts toward internationalization to increase the visibility of its activities. The creation of components within other global networks and a journal were the first steps marking this desire for international sharing. With the number of environments affected by occupational health and safety (OHS), research activities in this field involve an interinstitutional and interdisciplinary research community. The QOHSRN’s strategic occupational safety component leads by example by involving researchers from all fields of study and various Quebec universities and research institutions. Research themes within the component are all equally diverse and complementary. They range from the study of occupational safety integration methods at the design stage to technical, organizational, normative, legislative and preventive methods, and the development of new protection devices and equipment. A portrait of the make-up of the QOHSRN’s strategic occupational safety component and its evolution from its creation to the QOHSRN’s 10th anniversary was also produced and analyzed to show its growing evolution.Les scientifiques ayant soulevés des préoccupations liées aux avancées technologiques et aux risques associés, la communauté scientifique québécoise a mis en place le regroupement stratégique sécurité du travail au sein du Réseau de recherche en santé et en sécurité du travail du Québec (RRSSTQ). Ceci a d’abord favorisé un premier rapprochement géographique des chercheurs facilitant ainsi l’échange et le transfert de connaissances. Grâce à leurs diverses thématiques de recherche, les premiers membres du regroupement ont fait un premier constat de la situation critique en matière de sécurité du travail au niveau industriel. Or, la sécurité du travail est l’affaire de tous et concerne tous les secteurs industriels, tous les milieux et tous les pays. Le regroupement stratégique sécurité du travail a développé ses efforts vers l’internationalisation dans un souci de plus grand déploiement de ses activités. Les créations de regroupements au sein d’autres réseaux mondiaux et d’une revue ont été les premières étapes marquant cette volonté de partage international. Devant le nombre de milieux auxquels la santé et sécurité au travail (SST) s’adresse, les activités de recherche dans le domaine impliquent un regroupement interinstitutionnel et interdisciplinaire. Le regroupement stratégique sécurité du travail du RRSSTQ montre l’exemple en impliquant des chercheurs venant de tous les domaines et de plusieurs universités et institutions de recherche québécoises. Les thématiques de recherche au sein du regroupement stratégique sont toutes aussi variées et complémentaires. Elles s’étendent de l’étude des moyens d’intégration de la sécurité du travail dans la conception à celle de moyens techniques, organisationnels, normatifs, législatifs de prévention, en passant par le développement de nouveaux dispositifs et d’équipements de protection. Un portrait de la constitution du regroupement stratégique sécurité du travail du RRSSTQ et de son évolution depuis sa création jusqu’à l’aube des dix ans du RRSSTQ a été aussi dressé et analysé pour montrer l’évolution croissante du regroupement stratégique sécurité du travail.A la par de los científicos que han resaltado las preocupaciones vinculadas a los progresos tecnológicos y a los riesgos asociados, la comunidad científica quebequense ha implementado un reagrupamiento estratégico sobre la seguridad ocupacional al interior de la Red de investigación en salud y seguridad ocupacional del Quebec (RRSSTQ). Esto ha favorecido un primer acercamiento geográfico de investigadores facilitando así el intercambio y la trasferencia de conocimientos. Gracias a sus diversas temáticas de investigación, los primeros miembros de dicho reagrupamiento han hecho una primera constatación de la situación crítica en materia de seguridad ocupacional a nivel industrial. Sin embargo, la seguridad ocupacional es de interés general y concierne todos los sectores industriales, todos los medios y todos los países. El reagrupamiento estratégico seguridad ocupacional ha desarrollado sus esfuerzos hacia la internacionalización con miras a un despliegue más vasto de sus actividades. La creación de reagrupamientos al interior de otras redes mundiales y de una revista han sido las primeras etapas que han marcado esta voluntad de compartir a nivel internacional. Dado los numerosos medios concernidos por la salud seguridad ocupacional, las actividades de investigación en el campo implican un reagrupamiento interinstitucional e interdisciplinario. El reagrupamiento estratégico seguridad ocupacional del RRSSTQ ilustra esta tendencia implicando investigadores que provienen de todos los campos y de varias universidades e instituciones de investigación quebequenses. Las temáticas de investigación al interior del reagrupamiento estratégico son tanto variadas que complementarias. Estas comprenden desde el estudio de los medios de integración de la seguridad ocupacional en la concepción hasta el estudio de los medios técnicos, organizacionales, normativos, legislativos de prevención, pasando por el desarrollo de nuevos dispositivos y de equipos de protección. Se ha elaborado y analizado también un estado de situación del reagrupamiento estratégico seguridad ocupacional del RRSSTQ desde su creación y su evolución durante los casi diez años de existencia de la RRSSTQ; y ésto, con la intención de mostrar la evolución creciente del reagrupamiento estratégico seguridad ocupacional

Physicochemical characterization of engineered nanoparticles under physiological conditions: Effect of culture media components and particle surface coating

The use of engineered nanoparticles (ENPs) in commercial products has increased substantially over the last few years. Some research has been conducted in order to determine whether or not such materials are cytotoxic, but questions remain regarding the role that physiological media and sera constituents play in ENP aggregation or stabilization. In this study, several characterization methods were used to evaluate the particle size and surface potential of 6 ENPs suspended in a number of culture media and in the presence of different culture media constituents. Dynamic light scattering (DLS) and fluorescence correlation spectroscopy (FCS) were employed for size determinations. Results were interpreted on the basis of ENP surface potentials evaluated from particle electrophoretic mobilities (EPM). Measurements made after 24 h of incubation at 37 °C showed that the cell culture medium constituents had only moderate impact on the physicochemical properties of the ENP, although incubation in bovine serum albumin destabilized the colloidal system. In contrast, most of the serum proteins increased colloidal stabilization. Moreover, the type of ENP surface modification played a significant role in ENP behavior whereby the complexity of interactions between the ENPs and the medium components generally decreased with increasing complexity of the particle surface. This investigation emphasizes the importance of ENP characterization under conditions that are representative of cell culture media or physiological conditions for improved assessments of nanoparticle cytotoxicity

Physicochemical characterization of the layer-by-layer self-assembly of polyphenol oxidase and chitosan on glassy carbon electrode

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