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Dissertations / Theses on the topic 'Interfacial processes'
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1
Hill, Emma. "Interfacial processes." Thesis, University of Oxford, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.300056.
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Harding, Mark S. "The kinetics of interfacial processes." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.336113.
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Walter, Andrew John. "Interfacial recognition and adsorption processes." Thesis, University of Leicester, 2006. http://hdl.handle.net/2381/29975.
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The design and function of receptors for molecular recognition is of vital importance for the construction of novel sensors. Initially the project has investigated the relationship between the shape of the active site of the receptor and its sensitivity and selectivity for analytes in solution. The techniques of electrochemistry, NMR and molecular modelling have been used to study materials interactions. An optimum receptor design was established for a range of analytes so that the surface of an electrode could be modified to create an analytical sensor. The specific adsorption of both the receptor and the analyte on the electrode surface were probed to produce an amperometric sensor for mandelic and lactic acids.;Subsequently, the project has involved the investigation of small molecule adsorption, recognition and permeation at polymer plant wax constituent layers that model leaf cuticles. Correlations have been sought between the responses to these surfactants/adjuvants and the wax compositions. At low levels of interaction, the quartz crystal microbalance was used as a gravimetric sensor of these processes. At higher levels of interaction, when permeation of the film is sufficient to plasticise it, the rheological effects were used to explore solvent/small molecule permeation. In each case, qualitative data was used to diagnose film rigidity vs. viscoelasticity and quantitative data to determine film mass (thickness) or shear moduli, as appropriate. The experimental measurements have been supported by a computer model derived from the processes occurring at the interface and the resultant changes in film viscoelasatic properties are discussed.
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Oseland, Elizabeth E. "Electrochemical studies of interfacial polymerisation processes." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/89097/.
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This thesis describes how electrochemical analytical techniques have been used to understand some of the physicochemical processes that underpin interfacial polymerisation reactions. A few of the reaction systems studied are currently used in the agrichemical industry for the formation of microcapsules for active ingredient encapsulation. Interfacial processes that take place at the oil-water interface of an epoxy-amine emulsion polymerisation system have been studied. Time-lapse microscopy of epoxide droplets in water or aqueous amine solutions has shown the effect of temperature on droplet dissolution and interfacial polymerisation. Quantitative kinetic data were extracted. A combination of microelectrochemical measurements at expanding droplets and finite element modelling has been used to measure the fast transfer of amine out of an organic phase comprised of epoxide and amine into the aqueous phase. Electrochemical impedance spectroscopy was used to monitor a growing poly(urea) film formed at a model liquid/liquid interface at the tip of a micropipette. A simple circuit diagram was used to model the liquid/liquid interface before and after film formation, highlighting how the presence of the film will increase interfacial resistance and decrease interfacial capacitance. Poly(urea) formation under a range of different reaction conditions was investigated using a combination of impedance versus time measurements and scanning electron microscopy. Finally, the polymerisation of acrylamide monomers at a solid/liquid interface for discrete surface functionalisation was examined using a combination of scanning electron microscopy and atomic force microscopy.
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Zhang, Jie. "New microelectrochemical techniques for probing interfacial processes." Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.392934.
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Evans, Nicholas John. "Development of electrochemical techniques for investigating interfacial processes." Thesis, University of Warwick, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340484.
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Rudd, Nicola Clare. "Micro- and nanoscale investigations of interfacial physicochemical processes." Thesis, University of Warwick, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445522.
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Su, Yu Chu Joan. "The effect of interfacial phenomena on high temperature processes." Thesis, Imperial College London, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.423096.
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Gooding, J. Justin. "The study of interfacial processes using channel electrode systems." Thesis, University of Oxford, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.359440.
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Macfie, Gavin. "Ultrasonic and photonic stimulation of solid/liquid interfacial processes." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.393414.
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Kuhl, Adam. "A technique to measure interfacial fracture toughness." Thesis, Georgia Institute of Technology, 1998. http://hdl.handle.net/1853/16626.
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Huang, Zhongjie. "Investigation of Interfacial Charge Transfer Processes in Energy Conversion Devices." The Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1448663899.
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McCleese, Christopher. "Femtosecond Time-Resolved Spectroscopy Studies of Interfacial Charge Separation Processes." Case Western Reserve University School of Graduate Studies / OhioLINK, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=case149182204612303.
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Chen, Xuesheng. "Precision cold forming modelling, interfacial thermal parameter investigation and tool design optimisation." Thesis, University of Strathclyde, 2002. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=23751.
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Precision cold forming process modelling, thermal contact conductance and optimum shrink-fitted die with profiled interference were studied. The aims of this work have been achieved using analytical, numerical and experimental approaches to the relevant subjects. Several features of the work are presented: (i) an application of systematic modelling IDEFO language, (ii) an equivalent asperity of surface that enables FE simulation of surface deformation and (iii) a shrink-fitted die with profiled interference, which enables compensation for component-error and necessary die surface pre-stresses. Cold forming process was modelled systematically by IDEFO language in general. The most often used iterations, including design and error-compensation procedures, were constructed; basic activities, inputs, resources and constraints were defined and decomposed. These provide a general procedure for precision cold forming design and a base for the following research of this work. A thermal contact conductance (h -value) experimental investigation was conducted based on steady-temperature measurements and devices. h -value as a function of surface texture and interfacial pressure was experimentally investigated; typically, the value changes from 10 kWm⁻²K⁻¹ to 150 kWm⁻²K⁻¹ for changes in surface texture from Ra = 0.3 0.5 , um to Ra =3-5, um , depending on interfacial pressure (<180 MPa). Based on surface measurements and mathematical work, an equivalent asperity for isotropic surface was presented to represent surface geometry. Uniqueness of the equivalent asperity enables simulation of surface deformation by FE technology. Surface textures under interfacial pressure up to 300 MPa were successfully predicted by FE simulations, results being in agreement with surface measurements. h -value is defined as a function of either contact area ratio or local interfacial pressure; a FE model and an approach of integration of local h -value were dev eloped; value of h was successfully predicted by the established FE model and integration. A profiled interference for shrink-fitting die was designed for component-errors compensation and die surface pre-stress. This was achieved by considering the relationship between die pre-deflection and the profiled interference by FE simulations and a minimisation procedure. Both, the equation and minimisation procedure to determine the profiled interference were established analytically. Uniform die surface direct compensation is combined with shrink-fitted die. Component-errors can be controlled to within a few microns.
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Bolognesi, Margherita. "Organic bulk-heterojunction photovoltaic devices: materials, device architectures and interfacial processes." Doctoral thesis, Universitat Rovira i Virgili, 2013. http://hdl.handle.net/10803/128202.
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Research on organic photovoltaic devices (OPV) has developed during the past 30 years, but especially in the last decade it has attracted scientific and economic interest triggered by a rapid increase in power conversion efficiencies. Thanks to the indtroduction of the bulk heterojunction (BHJ) concept, today BHJ OPV efficiencies are exceeding 9%. This thesis gives an overview on the different possible strategies that could be adopted for a further. improvement of BHJ OPV devices performances. The accurate analysis of the chemical, energetic and physical criteria governing the solar cells functioning allowed to individuate some critical aspects and apply possible solutions by a fine tuning of the materials chemical structures, device processing techniques and device architecture engineering. Even though noit in all cases the applied strategy successfully led to device efficiency improvements, the fundamental understanding of some of the efficiency limiting factors could serve as useful scientific basis for future developments.
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Hu, Weiwei. "Characterization of hydrodynamic forces and interfacial phenomena in cell culture processes." Columbus, Ohio : Ohio State University, 2007. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1167409370.
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Kinnear, Sophie L. "Development and application of electrochemical scanning probe microscopy techniques for studying interfacial processes." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/77508/.
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This thesis is concerned with the construction of new electrochemical scanning probe microscopes. Designed to support a wide variety of existing techniques as well as to develop new techniques. This exibility was achieved by basing the equipment around a field programmable gate array card (FPGA), which allows for a software program to be configured on the physical FPGA card as hardware. This technology provides the efficiency and high speed of bespoke hardware and can be reprogrammed like software. The instrumentation was programmed in-house using the graphical programming language, LabVIEW, which allowed for changes and upgrades to be made when necessary. Two branches of projects were studied with the FPGA instrumentation, crystal dissolution and surface charge mapping. For the crystal dissolution studies, dual-barrel conductance micropipettes were used to investigate the dissolution of NaCl and calcite, with microscale spacial resolution. This technique had many advantages over traditional methods. For instance, high temporal resolution in the order of sub-milliseconds was achieved through the employment of in-house built current followers. In addition, fast mass transport inside the pipette allowed the study of surface kinetic processes. The implementation of finite element method simulations complemented the experimental findings, by enabling the quantitative analysis of the data to extract intrinsic dissolution rate constants. The technique is also complemented by atomic force microscopy, which provides an alternative method for analysing the etch pits. The same equipment is used as a scanning ion conductance microscope (SICM) to investigate the surface charge of both conductive and non-conductive surfaces. A double electric layer forms at the solid-liquid interface of a sample that is immersed in electrolyte solution, at low ionic strength the thickness of the double layer increases, which enables its detection via the SICM pipette. The formation of the double layer at the pipette walls induces ion current rectification, at the same time a surface induced rectification arises as the nanopipette approaches the substrate surface. The combination of these results in the creation of an ion perm-selective region, which results in an increase or decrease in current that is proportional to surface charge. Point measurements, maps and CVs of dynamically changing surfaces have been recorded.
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Bawazeer, Tahani Mohammad. "Developments of new techniques for studies of coupled diffusional and interfacial physicochemical processes." Thesis, University of Warwick, 2012. http://wrap.warwick.ac.uk/56925/.
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This study is concerned with the development and application of electrochemical techniques combined with confocal laser scanning microscopy (CLSM) as a probe of the kinetics of electrochemical and surface reactions at different interfaces. A CLSM set up has been designed which combines electrochemical and microscopic techniques to extend the applications of CLSM in a new research fields. This methodology has been applied to various electrochemical systems in this thesis. The electrochemical activity of ultramicroelectrodes (UMEs) has been quantified using CLSM. A special optically transparent electrode, comprising a thin film of carbon nanotube network has been developed for these studies. The methodology comprises of tracking the dynamic, reversible concentration profiles of electroactive and photoactive tris(2,2'- bipyridine)ruthenium(II) species in aqueous solutions during cyclic voltammetry experiments. A decrease of the solution intensity is recorded at and around the UME surface during the oxidation of luminescent Ru(bpy)3 2+ to non-luminescent Ru(bpy)3 3+, followed by an increase of the intensity signal in the reverse scan direction as the oxidized Ru(bpy)3 3+ is consumed at the electrode surface. A three dimensional map of the concentration gradients of Ru(bpy)3 2+ is constructed by collecting sections of the object across the normal to the electrode plane at the steady state current regime. The first use of CLSM coupled with scanning electrochemical microscopy (SECM) has been introduced as a means of time dependent visualisation and measurement of proton dispersion at dental enamel surfaces and the effectiveness of inhibitors on substrates. This new technique provides an analytical method with high spatial and temporal resolution permitting sub-second analysis of treatment effects on enamel substrates. In this case the UME tip of SECM is used to generate protons galvanostatically in a controlled manner and the resulting proton fields were quantified by CLSM using a pH sensitive fluorophore. Given the advantage of SECM to deliver high controllable, and local acid challenges in a defined way, and the high temporal and spatial resolution in the millisecond and micrometer range, respectively, in CLSM allows the surface kinetics of dissolution and the effect of barriers on the enamel surfaces to be evaluated. Finite element model has been used to describe the dissolution process, which allows the kinetics to be evaluated quantitatively, simply by measuring the size of pH profiles over time. Fluoride and zinc were used as treatments for enamel surfaces to investigate the effect of inhibitors on proton distribution, since they are generally considered to impede the dissolution process. Proton lateral diffusion at modified surfaces was also investigated using CLSM and SECM to validate the use of these techniques. A disc UME was brought close to the membrane and the oxidation of water was induced. Proton lateral diffusion was observed as a change in pH along the membrane. Different electrostatic interactions were investigated by functionalising the surface with different phospholipid head group and polypeptide multilayer films, since they are thought to have an effect on facilitate or retreat the process. Anionic lipids head groups share protons as acid-anion dimmers and thus trap and conduct protons along the head group domain of bilayers that contain such anionic lipids. The results also indicate the rate and mobility of proton diffusion along membrane are largely determined by the local structure of the bilayer interface.
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Savastano, Cesar Alberto. "Interfacial phenomena and rate processes in the extraction of nickel by mixed reagents." Thesis, Imperial College London, 1988. http://hdl.handle.net/10044/1/47247.
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Schwab, Scott Daniel. "Development of Raman spectrometry for remote sensing and the examination of interfacial processes /." The Ohio State University, 1986. http://rave.ohiolink.edu/etdc/view?acc_num=osu1487266362337776.
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Perez, Perez Francisco Javier. "Modelling microstructural and interfacial phenomena in welding and irradiation processes for Fe-based systems." Thesis, Loughborough University, 2000. https://dspace.lboro.ac.uk/2134/11167.
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In this thesis, different modelling techniques, including physically based molecular dynamics simulations and empirical models using neural network architectures have been used to address particular problems in the understanding of microstructural development in iron-based systems. The two main areas of investigation are concerned with the prediction of composition and mechanical properties of steel welds and the effect of irradiation on the grain boundary microstructure of a-iron, both very important industrial issues. Microstructural evolution models in steel welds require weld metal composition as their starting point. Extensive analyses have been carried out concerned particularly with the prediction of weld metal chemistry, and also complex mechanical properties such as toughness, using neural network techniques and a database developed for one pass per side submerged arc welds typical of those used in the manufacture of linepipe. The neural network techniques used were based on a Bayesian framework, implemented using Markov chain Monte Carlo methods. The results showed a significant advantage in the use of neural network models for prediction of toughness compared with simpler regression analyses. In order to study the effects of irradiation on the structure of Fe-based systems, a molecular dynamics methodology was initially set up to study the equilibrium relaxed atomic configuration of symmetric tilt and twist grain boundaries in a-iron. These structures have been classified in terms of both the energy and width of the grain boundary region and the atomic arrangement has been also analysed for the tilt models in terms of structuraJ units. Radiation damage has then been studied near the relaxed structures of a symmetrical tilt and a symmetrical twist boundary in a-iron. Collision cascades have been initiated.inthe structure by imparting an initial energy of 1 keY to a single Fe atom, i.e. a primary knock-on atom (PKA). The subsequent interaction of the cascade with the grain boundary has been studied using molecular dynamics simulations. As a result of radiation, reordering is produced in the atomic structure of the boundaries, the damage being more pronounced in the twist model studied. Clusters of interstitial atoms are produced at the boundary. Changes in the properties of the interfaces after irradiation are discussed.
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Degabriel, Thomas. "Study of the interaction between proteins and TiO2 NPs : nature of the interfacial processes." Thesis, Paris 6, 2015. http://www.theses.fr/2015PA066660/document.
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L’utilisation de nanoparticules (NPs) dans un milieu biologique est de plus en plus importante, alors que leur assimilation et leur toxicité reste peu maitrisée. Dans ce contexte l’objectif de ce travail est d’étudier l’interaction entre nanoparticules de dioxyde de titane (TiO2) avec des protéines ainsi que leur possible impact sur leurs propriétés structurales. Trois protéines d’intérêt ont été choisies: une protéine de la matrice extra cellulaire, le collagène, et deux protéines du plasma sanguin, l’albumine et le fibrinogène. Le choix a été basé sur l’importance biologique de ces protéines lors des interactions avec des NPs et sur la différence de leurs structures tridimensionnelles. L’étude de l’interaction protéine-NPs a été réalisée en solution et en phase adsorbée dans différentes conditions de température et de temps d’incubation. Dans un premier temps des nanoparticules de dioxyde de titane ont été synthétisées par voie solvothermale, afin d’obtenir des nanoparticules de tailles et de formes contrôlées. Deux types de nanoparticules ont été sélectionnés en vues d’étudier l’effet de forme et de taille sur l’interaction protéines-nanoparticules: des nano-sphères de diamètre de 8 à 10 nm et des nano-bâtonnets d’environ 8 nm de largeur et 23 nm longueur. Leur comportement en solution physiologique ainsi que leur réactivité ont été caractérisé par DSL et absorption UV montrant une inhibition des propriétés catalytiques ainsi qu’une forte agrégation en solution tampon phosphate saline (PBS). Dans un deuxième temps les propriétés d’adsorption du collagène en présence de nanoparticules furent étudiées sur deux types de surfaces l’une hydrophobe et l’autre hydrophile par XPS et imagerie AFM ainsi que par des mesures de forces AFM. Le comportement du collagène en solution en présence de nanoparticules a été caractérisé par ATR liquide. Les observations suggèrent que la formation des fibrilles à l’interface surface-solution de collagène est affectée par le caractère hydrophobe ou hydrophile de la surface ainsi que par la présence de nanoparticules. Enfin les propriétés d’adsorption de la HSA et du fibrinogène en présence de nanoparticules furent étudiées sur une surface hydrophile par imagerie AFM et analyses XPS. Leur comportement en solution en présence de nanoparticules fut étudié par ATR liquide. Les résultats suggèrent deux comportements différents des protéines en présence de nanoparticules pouvant être attribués propriétés physicochimiques différentes des protéines. La HSA subit d’importants changements structuraux en présence de nanoparticules contrairement au fibrinogène.L’étude en phase liquide de l’interaction protéine-nanoparticules couplé à l’étude en phase adsorbées des protéines permet de déterminer les phénomènes impliqués lors de cette interaction ainsi que leurs conséquences sur les protéines, de plus l’utilisation de nanoparticules de taille et forme différentes permet d’étudier la sensibilité des protéines à ces facteurs<br>The extensive use of NPs in a biological environment raises the problem of their assimilation or their toxicity, the main objective of this work is to study the interaction of TiO2 NPs with proteins as well as their possible impact on the structural properties of proteins. Three proteins were chosen, a protein of the extracellular matrix, the collagen, and two proteins of the plasma blood, the albumin and the fibrinogen for their biological importance as well as for their various tridimensional structures. The study of the protein-nanoparticle interaction was realized in solution and in the adsorbed phase under various condition of temperature and incubation time. First, titanium dioxide NPs were synthesized by a solvothermal method, NPs with controlled size and form were obtained. Two types of NPs were selected in order to study the effect of shape and size on the protein-NPs interaction: nano-spheres with a diameter of 8 to 10 nm and nano-rods with a width about 8 nm and a length of 23 nm. The behavior in physiological solution as well as the reactivity were characterized by DSL and UV absorption showing an inhibition of catalytic properties as well as a strong aggregation in phosphate buffer saline solution (PBS). Second, the adsorption properties of the collagen in the presence of NPs were studied on two kinds of surfaces, one hydrophobic and the other hydrophilic by XPS and AFM imaging as well as by AFM force measurements. The behavior of the collagen in solution in the presence of NPs was characterized by liquid ATR. The observations suggest that the formation of fibrils at the surface- collagen solution interface is affected by the hydrophobic or the hydrophilic character of the surface as well as by the presence of NPs. In the last part the adsorption properties of HSA and fibrinogen in the presence of NPs were studied on a hydrophilic surface by AFM imaging and XPS analyses. Their behaviors in solution in the presence of NPs were studied by liquid ATR. The results suggest two different behaviors of proteins in the presence of NPs, which can be attributed to the different physico-chemical properties of the proteins. HSA undergoes important structural changes in the presence of NPs but not fibrinogen. The study in the liquid phase of the protein-nanoparticle interaction, coupled to study of proteins in the adsorbed phase allows determining the involved phenomenon during the protein-nanoparticle interaction as well as the consequences on protein adsorption. Moreover, the use of NPs with different sizes and shapes revealed the sensitivity of proteins to these factors
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Degabriel, Thomas. "Study of the interaction between proteins and TiO2 NPs : nature of the interfacial processes." Electronic Thesis or Diss., Paris 6, 2015. http://www.theses.fr/2015PA066660.
Full textAbstract:
L’utilisation de nanoparticules (NPs) dans un milieu biologique est de plus en plus importante, alors que leur assimilation et leur toxicité reste peu maitrisée. Dans ce contexte l’objectif de ce travail est d’étudier l’interaction entre nanoparticules de dioxyde de titane (TiO2) avec des protéines ainsi que leur possible impact sur leurs propriétés structurales. Trois protéines d’intérêt ont été choisies: une protéine de la matrice extra cellulaire, le collagène, et deux protéines du plasma sanguin, l’albumine et le fibrinogène. Le choix a été basé sur l’importance biologique de ces protéines lors des interactions avec des NPs et sur la différence de leurs structures tridimensionnelles. L’étude de l’interaction protéine-NPs a été réalisée en solution et en phase adsorbée dans différentes conditions de température et de temps d’incubation. Dans un premier temps des nanoparticules de dioxyde de titane ont été synthétisées par voie solvothermale, afin d’obtenir des nanoparticules de tailles et de formes contrôlées. Deux types de nanoparticules ont été sélectionnés en vues d’étudier l’effet de forme et de taille sur l’interaction protéines-nanoparticules: des nano-sphères de diamètre de 8 à 10 nm et des nano-bâtonnets d’environ 8 nm de largeur et 23 nm longueur. Leur comportement en solution physiologique ainsi que leur réactivité ont été caractérisé par DSL et absorption UV montrant une inhibition des propriétés catalytiques ainsi qu’une forte agrégation en solution tampon phosphate saline (PBS). Dans un deuxième temps les propriétés d’adsorption du collagène en présence de nanoparticules furent étudiées sur deux types de surfaces l’une hydrophobe et l’autre hydrophile par XPS et imagerie AFM ainsi que par des mesures de forces AFM. Le comportement du collagène en solution en présence de nanoparticules a été caractérisé par ATR liquide. Les observations suggèrent que la formation des fibrilles à l’interface surface-solution de collagène est affectée par le caractère hydrophobe ou hydrophile de la surface ainsi que par la présence de nanoparticules. Enfin les propriétés d’adsorption de la HSA et du fibrinogène en présence de nanoparticules furent étudiées sur une surface hydrophile par imagerie AFM et analyses XPS. Leur comportement en solution en présence de nanoparticules fut étudié par ATR liquide. Les résultats suggèrent deux comportements différents des protéines en présence de nanoparticules pouvant être attribués propriétés physicochimiques différentes des protéines. La HSA subit d’importants changements structuraux en présence de nanoparticules contrairement au fibrinogène.L’étude en phase liquide de l’interaction protéine-nanoparticules couplé à l’étude en phase adsorbées des protéines permet de déterminer les phénomènes impliqués lors de cette interaction ainsi que leurs conséquences sur les protéines, de plus l’utilisation de nanoparticules de taille et forme différentes permet d’étudier la sensibilité des protéines à ces facteurs<br>The extensive use of NPs in a biological environment raises the problem of their assimilation or their toxicity, the main objective of this work is to study the interaction of TiO2 NPs with proteins as well as their possible impact on the structural properties of proteins. Three proteins were chosen, a protein of the extracellular matrix, the collagen, and two proteins of the plasma blood, the albumin and the fibrinogen for their biological importance as well as for their various tridimensional structures. The study of the protein-nanoparticle interaction was realized in solution and in the adsorbed phase under various condition of temperature and incubation time. First, titanium dioxide NPs were synthesized by a solvothermal method, NPs with controlled size and form were obtained. Two types of NPs were selected in order to study the effect of shape and size on the protein-NPs interaction: nano-spheres with a diameter of 8 to 10 nm and nano-rods with a width about 8 nm and a length of 23 nm. The behavior in physiological solution as well as the reactivity were characterized by DSL and UV absorption showing an inhibition of catalytic properties as well as a strong aggregation in phosphate buffer saline solution (PBS). Second, the adsorption properties of the collagen in the presence of NPs were studied on two kinds of surfaces, one hydrophobic and the other hydrophilic by XPS and AFM imaging as well as by AFM force measurements. The behavior of the collagen in solution in the presence of NPs was characterized by liquid ATR. The observations suggest that the formation of fibrils at the surface- collagen solution interface is affected by the hydrophobic or the hydrophilic character of the surface as well as by the presence of NPs. In the last part the adsorption properties of HSA and fibrinogen in the presence of NPs were studied on a hydrophilic surface by AFM imaging and XPS analyses. Their behaviors in solution in the presence of NPs were studied by liquid ATR. The results suggest two different behaviors of proteins in the presence of NPs, which can be attributed to the different physico-chemical properties of the proteins. HSA undergoes important structural changes in the presence of NPs but not fibrinogen. The study in the liquid phase of the protein-nanoparticle interaction, coupled to study of proteins in the adsorbed phase allows determining the involved phenomenon during the protein-nanoparticle interaction as well as the consequences on protein adsorption. Moreover, the use of NPs with different sizes and shapes revealed the sensitivity of proteins to these factors
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Tang, Zhenming. "Interfacial reliability of Pb-free flip-chip BGA package." Diss., Online access via UMI:, 2008.
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Thesis (Ph. D.)--State University of New York at Binghamton, Thomas J. Watson School of Engineering and Applied Science, Department of Mechanical Engineering, 2008.<br>Includes bibliographical references.
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Johnson, Mark Adam. "A quantitative framework for understanding the complex interactions of competing interfacial processes and in-situ biodegradation." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1895.
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Thesis (M.S.) -- University of Maryland, College Park, 2004.<br>Thesis research directed by: Dept. of Civil and Environmental Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Ergezen, Ertan Lec Ryszard. "A multi-resonance thickness-shear mode (MTSM) measurement technique for quantitative characterization of biological interfacial processes /." Philadelphia, Pa. : Drexel University, 2010. http://hdl.handle.net/1860/3198.
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Jenkins, Judith Lynn. "Spectroscopic and Spectroelectrochemical Characterization of Fundamental Interfacial Charge Transfer Processes Relevant to Efficient Solar Energy Conversion." Diss., The University of Arizona, 2012. http://hdl.handle.net/10150/255173.
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Solar energy conversion is accomplished by multilayered devices consisting of various conducting and semiconducting materials. Because the layers are only 10s - 100s of nm thick, device behavior is governed primarily by interfacial molecular dynamics that often differ from the bulk behavior of these materials. The thermodynamics and kinetics of the interfacial interactions are particularly interesting, as interfacial electron transfer strongly influence the efficiency of photovoltaics and devices used in solar hydrogen production. This work focuses specifically on interfacial charge transfer processes occurring at three interfaces relevant to thin film organic/inorganic solar energy conversion devices. i) A potential-step polymer electrochemical deposition and doping procedure was developed and used to create poly(3-hexylthiophene) (e-P3HT) interlayer films for organic photovoltaics. Photoelectron spectroscopies suggest that an interface dipole forms spontaneously at the polymer donor/fullerene acceptor interface through partial interfacial charge transfer prior to photoexcitation; this doping-dependent interfacial dipole was correlated to the electrical properties of these critical heterojunctions. ii) Potential-modulated fluorescence spectroscopy (PMF) was developed and used examine the kinetics of the reversible oxidation of the (e-P3HT) films in attempt to elucidate the ITO/e-P3HT charge transfer rates. However, the optical switching increased linearly as the polymer film decreased, indicating that the molecular-level process probed by PMF was rate-limited by counter-ion movement into and out of the polymer film. iii) Potential-modulated attenuated total reflectance spectroscopy (PM-ATR) was used to examine the reversible reduction of CdSe semiconductor nanocrystals tethered to indium tin oxide electrodes as well as the surface-coverage dependent bleaching of these nanocrystals. A new equivalent circuit model describing the CdSe/ITO electrode is proposed, and a PM-ATR simulation program was used to quantify Faradiac resistances to interfacial charge transfer that trend with the magnitude of overpotential. The insights gained through these experiments add to a growing understanding of the fundamental, molecular-level competition between photoinduced charge generation and parasitic charge recombination at these critical interfaces.
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Strandlund, Henrik. "Simulation of diffusional processes in alloys : techniques and applications." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-399.
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Schnippering, Mathias. "Development and application of evanescent wave cavity ring-down spectroscopy for studies of electrochemical and interfacial processes." Thesis, University of Warwick, 2009. http://wrap.warwick.ac.uk/3787/.
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This thesis is concerned with the application of evanescent wave cavity ring-down spectroscopy (EW-CRDS) and evanescent wave broadband cavity enhanced absorption spectroscopy (EW-BB-CEAS) for studies of electrochemical and interfacial processes. These include nanoparticle adsorption/dissolution, polymer nanoparticle formation and surface-bound electrochemical redox reactions. Different experimental setups have been designed to investigate these systems. EW-CRDS is a surface sensitive technique, which allows absorption measurements at solid/liquid and solid/air interfaces. Surface reactions can easily be monitored in real time. A pulsed or modulated laser beam is coupled into an optical cavity which consists of at least one optical element, in which the beam is total internal reflected. At the position of total internal reflection (TIR), an evanescent field is established with the amplitude decaying exponentially with distance from the boundary. The evanescent field can be exploited to investigate the absorbance properties of the liquid phase in the first few hundred nanometres of the solution above the silica surface. These types of instruments have high temporal resolution (up to 2 kHz repetition rate), coupled with high sensitivity (minimum detectable interfacial absorbance per pass: ~80 ppm) which enables the investigation of a variety of processes relating to fundamental questions in the field of physical chemistry and materials science. The aforementioned sensitivity and resolution make EW-CRDS an ideal tool for those investigations, especially if combined with other techniques such as electrochemistry or microfluidic and hydrodynamic techniques. In this thesis, different instrumentational setups will be discussed. EW-BB-CEAS is another example for a TIR based absorption spectroscopic technique and can give additional spectral information about the investigated surface processes by employing broadband light such as supercontinuum radiation. In this case, the amplified light intensity within the optical cavity is measured rather than the light decay. By employing complementary techniques, such as electrochemistry and atomic force microscopy and by fitting experimental data using finite-element modelling, surface processes can not only be described accurately but also kinetic information such as rate constants for the aforementioned systems can be calculated.
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Barulina, Elena. "Study of the photostability of organic solar cells : impact of materials and encapsulation processes." Electronic Thesis or Diss., Aix-Marseille, 2020. http://theses.univ-amu.fr.lama.univ-amu.fr/201209_BARULINA_247fcnnrd470uh345hs973z_TH%20(1).pdf.
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Malgré une forte progression des rendements de conversion électrique des cellules solaires organiques, leur stabilité à long terme est un facteur clé pour leur viabilité commerciale et doit donc être examinée en détail. L'objectif était ici d’étudier la durée de vie des cellules solaires organiques en variant les matériaux actifs du mélange D:A, l'architecture des cellules, les couches interfaciales, les traitements appliqués et le processus d'encapsulation. Quel que soit ces paramètres, une grande stabilité a pu être obtenue pour des dispositifs à base de PC71BM sous LED. Par contre sous AM1.5, un post-recuit améliore considérablement la stabilité des dispositifs, mais le choix de la structure de la cellule reste le paramètre clé où seules les cellules en structure normale ont montré une grande stabilité dans le temps. Ces couches ont été étudiées par spectroscopie d'absorption, AFM, XRD et TEM analytique. Les dispositifs à base de PC71BM peuvent ainsi servir de référence dans l’étude de la stabilité des mélanges à base de NFAs (PBDB-T:ITIC et PBDB-T-2F:ITIC-4F). Outre l’éclairage (LED ou AM1.5) et les divers paramètres, les cellules solaires à base de NFA sont instables. Sous LED, les cellules solaires à base d’ITIC-4F présentent une meilleure stabilité que celles à base d'ITIC mais cette dégradation dépend aussi très fortement de la nature chimique de la couche d’extraction d’électron. Des procédés d'encapsulation flexibles sur les modules imprimés par jet d'encre de la société Dracula Technologies ont été évalués. Ces modules ont démontré des propriétés relativement stables après 1000 heures d'éclairage continu par une lampe au xénon non filtrée en UV<br>Despite a strong increase in the electrical conversion efficiencies of organic solar cells, their long-term stability is a key factor for their commercial viability and therefore needs to be examined in detail. The objective here was to study the lifetime of organic solar cells by varying the active materials in the D:A mixture, the cell architecture, the interfacial layers, the treatments applied and the encapsulation process. Regardless of these parameters, a high stability could be obtained for PC71BM-based devices under LED. On the other hand, under AM1.5, a post-annealing process considerably improves the stability of the devices, but the choice of the cell structure remains the key parameter where only cells with normal structure showed a high stability over time. These layers were studied by absorption spectroscopy, AFM, XRD and analytical TEM. PC71BM-based devices can thus serve as a reference in the study of the stability of mixtures based on NFAs (PBDB-T:ITIC and PBDB-T-2F:ITIC-4F). Regardless of the illumination (LED or AM1.5) and the various parameters, NFA-based solar cells are unstable. Under LEDs, ITIC-4F-based solar cells have a better stability than ITIC-based solar cells, but this degradation also depends very strongly on the chemical nature of the electron extraction layer. Flexible encapsulation processes on ink-jet-printed modules from Dracula Technologies have been evaluated. These modules demonstrated relatively stable properties after 1000 hours of continuous illumination by a non-UV-filtered xenon lamp
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Abdalla, Mohamed A. "Carbon nanotube/epoxy nanocomposites effect of interfacial chemistry and processing on molecular mobility, cure behavior, morphology and properties /." Birmingham, Ala. : University of Alabama at Birmingham, 2008. https://www.mhsl.uab.edu/dt/2009r/abdalla.pdf.
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Thesis (Ph. D.)--University of Alabama at Birmingham, 2008.<br>Additional advisors: Gregg M. Janowksi, Tamara Floyd Smith, Gregory B. Thompson, Uday Vaidya. Description based on contents viewed July 7, 2009; title from PDF t.p. Includes bibliographical references.
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Jackman, R. B. "Interfacial chemistry of metal carbonyls, metal halides and halogens : Surface studies with application to photon and electron enhanced processes on semiconductors." Thesis, University of Southampton, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.374568.
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Theron, Félicie. "Conception et mise en œuvre d'un procédé intensifié continu de microencapsulation par polycondensation interfaciale." Thesis, Toulouse, INPT, 2009. http://www.theses.fr/2009INPT045G/document.
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De nombreux produits encapsulés sont utilisés dans la vie quotidienne. Crèmes cosmétiques, peintures, et pesticides en sont quelques exemples. De nos jours, de plus en plus de technologies innovantes mettent en jeu des substances encapsulées. La microencapsulation a permis à de nouveaux « textiles intelligents » de voir le jour, tels que les textiles sur lesquels sont fixées des microcapsules qui libèrent un principe actif amincissant, odorant, hydratant ou encore répulsif pour les insectes. Les microcapsules sont des produits à fortes valeur ajoutée, dont les propriétés sont nombreuses, et délicates à maîtriser toutes à la fois. Si l'étape de formulation a pour objectif de trouver la recette optimale pour répondre le mieux possible au cahier des charges, le type de procédé de fabrication choisi doit garantir une production homogène dans le temps, sans écarts par rapports aux propriétés attendues. L'objectif de ces travaux est de proposer une alternative continue aux procédés batch traditionnellement mis en œuvre pour l'encapsulation par polycondensation interfaciale, coûteux en termes d'investissement et de frais de fonctionnement. L'encapsulation par polycondensation interfaciale est constituée d'une étape d'émulsification suivie d'une étape réactive. Nous proposons un procédé découplant ces deux étapes grâce à deux technologies adaptées aux contraintes hydrodynamiques respectives de chaque étape. Cette étude est réalisée sur la base d'un système modèle espèce encapsulée / membrane polymérique. L'étape d'émulsification est réalisée en mélangeurs statiques en régime turbulent. Des mesures de pertes de charge en écoulements monophasiques ont permis de mettre en évidence l'apparition de ce régime et d'établir des corrélations représentant ces pertes de charge a travers l'emploi des nombres adimensionnels que sont le nombre de Reynolds et le facteur de friction. Concernant l'émulsification, nous évaluons l'influence de différents paramètres sur les performances de l'opération en termes de tailles de gouttes obtenues en fonction du coût énergétique. Nous comparons également les performances de trois designs de mélangeurs statiques commercialisés par la société Sulzer, et corrélons les résultats obtenus en termes de diamètres moyens de Sauter en fonction des nombres de Reynolds et de Weber. L'étape réactive est tout d'abord mise en œuvre en réacteur agité afin d'étudier la cinétique de la réaction, et d'acquérir des temps de réactions qui permettent par la suite de dimensionner le réacteur continu. Enfin cette étape est réalisée dans deux types de réacteurs continus : le réacteur Deanhex, développé et étudié par Anxionnaz et al. (2009), ainsi qu'un réacteur tubulaire en serpentin. Cette dernière étude consiste d'une part à valider le passage au continu à travers la conservation de la granulométrie des gouttelettes de l'émulsion durant la réaction, et la conservation de la vitesse apparente de la réaction. Enfin, les conditions hydrodynamiques favorables présentées par les réacteurs continus permettent d'apporter de nouvelles voies d'intensification au procédé en augmentant d'une part la concentration en capsules dans le réacteur, et en s'affranchissant de l'emploi du tensioactif utilisé pour stabiliser les gouttes de l'émulsion. Ce procédé, proposé pour la production en continu de microcapsules, offre une amélioration en termes de qualité du produit et de coût par rapport aux procédés traditionnels en batch mis en œuvre dans l'industrie<br>The aim of the present work is to propose a continuous alternative to batch processes classically used to carry out encapsulation by interfacial polycondensation that represent high investment and working costs. Encapsulation by interfacial polycondensation consists in an emulsification step followed by a reactive step. We propose here a process decoupling these two steps using technologies well adapted to hydrodynamic issues of each step. This study is realised on the basis of model system. The emulsification step is carried out in static mixers under turbulent flow. Pressure drop measurements in single-phase flow enable to highlight this flow regime and to establish correlations representing these pressure drops in terms of dimensionless numbers: the Reynolds number and the friction factor. About emulsification we evaluate the influence of different parameters on the operation performances in terms of mean droplets size as a function of energy cost. We compare the performances of three different Sulzer static mixers and correlate results obtained in terms of Sauter mean diameter as a function of Reynolds and Weber numbers. The reactive step has been first carried out is stirred tank in order to study the reaction kinetics and to acquire reaction times necessary to design continuous reactors. Finally this step has been realised using two continuous reactors: the Deanhex reactor (Anxionnaz et al., 2009) and a coiled tube reactor. This last study consists first in validating the continuous process through the conservation of the emulsion size distribution during encapsulation and the conservation of the apparent kinetics. Finally the favourable hydrodynamic conditions presented by continuous reactors offer new ways of intensification to the process. In fact it is possible to increase the microcapsule concentration in the reactor and to work without surfactant to stabilize the emulsion. This continuous process for microcapsules production offers improvements in terms of product quality and working costs compared to traditional batch process used in the industry
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Muhmood, Luckman. "Investigations of thermophysical properties of slags with focus on slag-metal interface." Doctoral thesis, KTH, Materialens processvetenskap, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-26611.
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The objective of this research work was to develop a methodology for experimentally estimating the interfacial properties at slag-metal interfaces. From previous experiments carried out in the division, it was decided to use surface active elements like sulfur or oxygen to trace any motion at the interface. For this purpose the following experimental investigations were carried out. Firstly the density of slag was estimated using the Archimedes Principle and the Sessile Drop technique. The density of the slag would give the molten slag height required for the surface active element to travel before reaching the slag-metal interface. Diffusivity measurements were uniquely designed in order to estimate the sulfur diffusion through slag media. It was for the first time that the chemical diffusivity was estimated from the concentration in the metal phase. Experiments carried out validated the models developed earlier. The density and diffusivity value of sulfur in the slag was used to accurately capture the time for sulfur to reach the slag-metal interface. The oscillations were identified by calculating the contact angle variations and the interfacial velocity was estimated from the change in the surface area of the liquid iron drop. The interfacial tension was estimated from the contact angles and the interfacial dilatational modulus was calculated. Based on cold model experiments using water as well as mercury, an equation of the dependence of the interfacial shear viscosity on the interfacial velocity and interfacial tension was established. This paved way for the estimation of the interfacial shear viscosity at the slag-metal interface. The present study is expected to have a strong impact on refining reactions in pyometallurgical industries where slag/metal interfaces play an important role. From a fundamental view point, this provides a deeper insight into interfacial phenomena and presents an experimental technique to quantify the same.<br>QC 20101130
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Chopart, Jean-Paul. "Approche microscopique des processus interfaciaux a une electrode sous controle magnetoelectrochimique." Reims, 1998. http://www.theses.fr/1998REIMS031.
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La determination de l'origine des effets crees par l'application d'un champ magnetique parallelement a la surface d'une electrode reste un sujet tres controverse. Apres une etude critique approfondie des resultats et des diverses interpretations donnees dans la litterature, il ressort que seuls des effets convectifs sont - a ce jour - prouves, a l'inverse de pretendus effets sur le transfert electronique. Pour expliquer le phenomene magnetohydrodynamique (mhd), nous prouvons (tant par l'analyse des resultats publies que par nos propres experiences) que l'idee d'une simple force de type lorentz-laplace ne peut rendre compte des resultats. Nous proposons une approche microscopique qui montre qu'une convection prend naissance dans la couche diffuse et resulte de la force induite sur la charge d'espace qui existe dans cette zone de l'interface ; ceci rend donc l'effet magnetohydrodynamique semblable dans ses effets a un phenomene electrocinetique. Par continuite des effets magnetoelectrochimiques au sein de la solution, nous determinons la loi de vitesse parietale induite. Cette vitesse est une fonction du champ electrique normal a l'electrode ; dans le cas d'un systeme electrochimique reversible et en presence d'un sel de fond, nous pouvons determiner ce champ pour toute valeur de polarisation et ainsi resoudre l'equation de diffusion convective. L'interpretation rend bien compte de l'evolution magneto-induite des courants limites de diffusion en fonction des differents parametres physiques impliques. L'analyse numerique des courants limites sous convection magnetique permet alors de determiner les grandeurs fondamentales retenues par notre modele, a savoir l'abscisse du plan de cisaillement (quelques nanometres) et l'intensite du champ electrique transverse dans la double couche. Une verification experimentale de cette demarche est proposee en realisant - en l'absence de tout champ magnetique - une electrode non-equipotentielle permettant de creer directement un champ electrique transverse induisant le meme type de convection et d'aborder les potentialites de cette nouvelle methode d'analyse des processus interfaciaux appelee ekhd.
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Hewlett, Robert. "Solution-processed lead zirconate titanate as an interfacial modifier in hybrid oxide/polymer solar cells." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24864.
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Due to its excellent optoelectronic properties and ease of processing. ZnO has been considered a promising acceptor material in oxide:polymer hybrid photovoltaics (hPVs); however, devices have consistently underperformed for a number of reasons including poor charge generation and high recombination rates. The characteristics of the oxide:polymer interface have been cited as crucial in determining device performance: to this end, modification of the interface with both molecular and inorganic species has been shown to yield significant improvement. In this study, growth of the perovskite ferroelectric material lead zirconate titanate (PZT) is carried out on ZnO using sol-gel deposition. Subsequently, the PZT layers are used to modify the donor-acceptor interface in ZnO:poly(3-hexylthiophene) (P3HT) hPV devices: this study is carried out in order to lay the foundations for future investigations into the effect of ferroelectric properties on organic-based photovoltaics using inorganic ferroelectric materials. PZT was confirmed to crystallise on ZnO in the tetragonal phase and microstructural characterisation by atomic force microscopy revealed that the ZnO-PZT films consist of small, tightly packed PZT grains, indicating that the ZnO substrates provide a high seeding density for PZT. The ZnO-PZT interface was studied to determine the way by which growth proceeds in these films: whilst it was found that intermixing between the constituent elements of the two materials does not occur, transmission electron microscopy of the interface revealed the presence of a secondary phase thought to be orthorhombic PbO - it is hypothesised that this phase plays a role in the crystallisation of PZT. Growth and characterisation of low thickness PZT (< 15 nm) was conducted, confirming the crystallisation of tetragonal PZT for a film thickness of ~ 11 nm. Finally, the modification of bilayer ZnO:P3HT hPV devices with PZT was shown to have a positive effect on device performance: using transient absorption spectroscopy, the presence of the PZT layer was seen to increase the hole polaron lifetime from 15 μs to 2 ms, indicating a suppression of charge recombination. The open-circuit voltage (Voc) of the hPV devices was observed to increase from 0.162 to 0.734 V; moreover, prolonged illumination of up to 30 minutes led to further increases in Voc, reaching a maximum of 0.947 V - this was attributed to the progressive filling of electron traps with photoexcited charges, leading to a reduction in trap-assisted charge recombination.
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Langlet, Jérémie. "Propriétés interfaciales des bactériophages ARN F-spécifiques : Implications lors des processus d’adhésion – agrégation." Thesis, Nancy 1, 2008. http://www.theses.fr/2008NAN10131/document.
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Les bactériophages ARN F-spécifiques sont couramment utilisés comme des modèles de virus entériques pathogènes pour l’homme car ils ont une taille (~ 25 nm) et une structure proches. Néanmoins, en dehors de leurs cellules hôtes, les phages, tout comme les virus pathogènes, sont des particules biologiques inertes dont le comportement dépendra directement des propriétés de surface. Paradoxalement, peu de données sont connues dans ce domaine alors que ce sont des aspects incontournables, tant d’un point de vue théorique pour développer de nouvelles approches adaptées aux particules biologiques, que d’un point de vue industriel pour limiter le risque viral. L’objectif de ce travail est de préciser les propriétés interfaciales de bactériophages ARN Fspécifiques (charge, hydrophobicité) en milieu aqueux et en tenant compte des spécificités des particules biologiques notamment de leur perméabilité hydrodynamique. Nous avons également cherché à relier ces propriétés aux capacités d’adhésion-agrégation des particules virales. Deux aspects sont abordés : l’élimination des virus par des procédés de filtration membranaire et l’impact de l’agrégation sur l’estimation du nombre d’unités infectieuses. Dans la première partie, nous avons défini la nature et les caractéristiques de l’interface du phage MS2 et son impact sur les mesures de mobilités électrophorétiques. Pour la première fois, nous décrivons le comportement électrocinétique de particules biologiques sphériques constituées de plusieurs couches molles (génome, génome accolé à la capside, capside protéique) en prenant en compte l’anisotropie chimique et structurale des particules. Il en résulte des mobilités négatives dues à une perméabilité élevée, d’un ordre de grandeur égal à l’épaisseur de la capside protéique ( 2 nm). Cette perméabilité permet au flux électro-osmotique de « sonder » la charge négative du génome du phage MS2 et montre que les virus ne peuvent pas être assimilés à des particules dures non perméables. Le potentiel zêta (?) n’est donc pas adapté à ce type de particule. Comme le génome a un impact sur la charge du virus, nous nous sommes intéressés à quatre phages ARN F-spécifiques ayant des tailles de génome différentes : ~ 3500 nucléotides pour les phages MS2 et GA, ~ 4200 nucléotides pour les phages Qß et SP. En combinant des mesures de tailles et de mobilités pour différentes valeurs de pH (de 1,5 à 7,5) et de forces ioniques (NaNO3, 1 et 100 mM), nous avons défini l’échelle d’hydrophobicité suivante : GA et SP > Qß > MS2. De même, en nous basant sur les mobilités électrophorétiques, il ressort que la charge négative du phage Qß sous forme isolée est plus importante que celle du phage MS2 (perméabilité hydrodynamique supposée comparable à l’état isolé). Le point isoélectrique (pI) de la littérature pour le phage Qß (5,3) a d’ailleurs été remis en cause (entre 1,9 et 2,7 dans cette étude). Les mobilités des phages SP et GA ne peuvent être comparées aux autres car ces phages sont sous forme agrégée et donc présentent une perméabilité hydrodynamique différente. Ces propriétés interfaciales différentes permettent d’expliquer le comportement des phages MS2 et Qß lors d’un traitement par filtration membranaire. Les membranes classiquement utilisées dans le cadre du traitement de l’eau sont hydrophiles et électronégatives. Or, c’est bien le phage Qß qui est toujours moins bien éliminé, quelle que soit la porosité de la membrane (ultrafiltration ou microfiltration). Nous avons par ailleurs démontré que les techniques rapides de RT-PCR en temps réel sont aussi adaptées que la technique de référence par plages de lyse (UFP). Finalement, dans certains cas, l’agrégation virale pourrait expliquer la baisse des unités infectieuses (UFP) du phage MS2 en solution. Cette agrégation peut entraîner une baisse d’UFP de 1 à 3 log10. La congélation cause également une perte d’UFP mais celle-ci est due à la dégradation du virus et non à son agrégation. Ainsi, les méthodes expérimentales et théoriques développées dans cette thèse ont abouti à une meilleure connaissance des propriétés interfaciales des phages ARN F-spécifiques. Les résultats fondamentaux obtenus ont également mené à des avancées méthodologiques pour des applications industrielles<br>thesis
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Langlet, Jérémie Gantzer Christophe Gaboriaud Fabien. "Propriétés interfaciales des bactériophages ARN F-spécifiques Implications lors des processus d'adhésion - agrégation /." S. l. : Nancy 1, 2008. http://www.scd.uhp-nancy.fr/docnum/SCD_T_2008_0131_LANGLET.pdf.
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Mas, Pujadas Francesc. "Mètode de les transformades integrals en l'obtenció de funcions resposta en processos electròdics, El." Doctoral thesis, Universitat de Barcelona, 1985. http://hdl.handle.net/10803/2753.
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L'electroquímica ha experimentat un salt significatiu en els darrers anys, donada la possibilitat de control dels sistemes experimentals mitjançant les innovacions tecnològiques. Malgrat això, el caire heterogeni dels processos electroquímics no permet el tractament teòric d'aquests sistemes, tant des d'un punt de vista macroscòpic, ja que un estudi així requeriria l'ús de la termodinàmica de processos irreversibles, la qual és inaplicable donat que a la regió interfacial no es verifica la hipòtesi d'equilibri local, peça clau d'aquesta teoria, com des d'un punt de vista microscòpic, ja que l'estructura ds la regió interfacial és d'una gran complexitat i encara no hi ha models microscòpics que ens descriguin les interfases d'una forma bastant general a menys que es simplifiqui molt el model. Això fa que existeixin formalismes aproximats que permeten estudiar els processos electròdics des d'un punt de vista cinètic on la interfase juga un paper secundari o té una definició purament geomètrica de separació de fases.<br/><br/>Cal esmentar que recenment s'ha desenvolupat una teoria general de sistemes (Kalman, Falb i Arbib - 1969; von Bertalanffy et al. - 1972, Aracil - 1978, Epelboin, Gabrielli i Keddam - 1984, entre d'altres) en el cas de no disposar d'una teoria concreta que descrigui el comportament del sistema i la seva evolució devant de pertorbacions externes.<br/><br/>La realització d'una experiència que permeti d'un cantó la regulació i llavors l'anàlisi de processos electròdics i per una altra banda, l'elaboració de models, els quals s'han de comparar amb les dades experimentals, requereix una descripció acurada de les lleis que governen el comportament elèctric i cinètic de la interfase.<br/><br/>Dins d'aquesta línia, el present treball es troba orientat a l'obtenció de funcions resposta de sistemes electroquímics tot utilitzant el mètode matemàtic de les transformades integrals. Si bé aquest mètode ha estat utilitzat en la resolució de determinats sistemes simples, la forma de tractar el problema, havia deixat pas a mètodes de linearització o de simulació numèrica per a resoldre problemes més complexes.<br/><br/>El mètode, que consisteix en transformar el conjunt d'equacions diferencials que descriuen l'evolució de les variables d'estat en un conjunt d'equacions integrals més fàcils de resoldre, s'ha generalitzat per a sistemes en què imposem unes poques hipótesis de caràcter físic. La funció resposta s'obté de forma exacta i permet garantir la bondat de possibles mètodes aproximats a propasar a partir de les equacions integrals. En efecte, en utilitzar el mètode de les aproximacions succesives, s'obtenen solucions analítiques per a aquestes equacions, o sinò sistemes d'equacions funcionals implícites més senzilles que el sistema, d'equacions integrals, tot retrobant les aproximarà ons possibles donades a la bibliografia per a estudiar els mateixos sistemes, la qual cosa ens dóna un marc general i unificat per a deduir de les equacions generals les solucions aproximades.<br/><br/>En el capítol II, s'ha fet un petit resum de l'estat actual de les teories físiques que ens descriuen les interfases electrificades, en particular les electròdiques. Això ens permet escollir quines són les variables d'estat que ens caracteritzaran la interfase.<br/><br/>El capítol III es centra en l'establiment de les equacions diferencials que ens descriuen l'evolució de les variables que ens caracteritza l'estat del sistema, així com de les condicions inicials i de contorn associades amb les característiques del procés i amb els lligams del sistema (variables de control).<br/>Dins dels mètodes matemàtics més emprats per a resoldre aquest tipus d'equacions que trobem en el capítol III, en el capítol IV esmentem els més importants, i d'entre ells destaquem el mètode de les transformades integrals que es el que desenvolupem en els capítols V i VI, dedicats l'un a trobar les variables d' estat i l'altra a trobar les funcions resposta, en especial la intensitat i la càrrega total,d'un procés elemental de transferència<br/>de càrrega, bescanviada a la interfase electròdica. Els sistemes estudiats, centrant-nos en llur geometria i règim hidrodinàmic, són l'elèctrode pla estacionari, l'elèctrode esfèric estacionari, l'elèctrode de gotes de mercuri, tant dins del model de pla en expansió com d'esfera, en expansió i l'elèctrod&ae disc rotatori.<br/><br/>En el capítol VII, es fa l'aplicació d'aquest formalisme a un exemple concret, el de la polarografia, que ha estat molt estudiat en casos sense complicacions degudes a l'adsorció a la interfase electròdica. En aquest cas s'han resol les equacions plantejades per a descriure el procés, amb les hipòtesis fetes en els darrers capítols, i quan l'adsorció dels components de la reacció segueixen una isoterma de Langmuir o de Frurnkin. Això ens permetrà valorar l'exactitud de les altres tècniques matemàtiques emprades per a resoldre aquest problema, generalment de forma aproximada, algunes de les quals es dedueixen de les equacions generals plantejades al aplicar el mètode d'aproximacions succesives per a resoldre les equacions integrals que surten. A més a més es veu l'aplicabilitat del mètode per a resoldre casos en què les tècniques convencionals no ho aconsegueixen o porten a equacions d'un grau molt elevat de complexitat per a dur-ho a la pràctica.<br/><br/>Aquest estudi es troba restringit als processos electròdics convencionals, puix que pot extendre's a la caracterització d'altres tipus de processos en què s'escaiguin hipòtesis similars. En particular, i a títol d'exemple, cal destacar l'ús d'aquest mètode en el futur esclariment de certs processos biològics, com ara el transport d'informació al cervell (González - 1984, Ghizmadzhev i Pastushenko - 1985) mitjançant el sistema nerviós.
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Zhang, Helin. "Enhancement of Municipal Wastewater Biosolids Drying through Interfacial Energy Modifying Amendments to Promote Uniform Agglomeration." Digital WPI, 2018. https://digitalcommons.wpi.edu/etd-theses/1263.
Full textAbstract:
Large quantities of biosolids are produced from treatment of municipal wastewater and can be processed into a nutrient and organic-rich soil amendment that has great value for agriculture. The drying process involves converting solids at approximately 25-30% solids content to a dry, stable biosolids pellet. The majority of the input material is recycled to the mixing step upstream of the dryer to achieve a more uniform particle size distribution. The objective of this work was to investigate use of polyelectrolyte amendments to promote uniformity in dried biosolids pellet size. Biosolids samples were collected at the New England Fertilizer Company (NEFCO) facility located in Quincy, MA, U.S. The biosolids samples were characterized by scanning electron microscopy (SEM), inductively coupled plasma/mass spectrometry (ICP-MS), dynamic light scattering (DLS) and zeta potential measurements. Five polyelectrolytes, polyethyleneimine (PEI), polydiallyldimethyl-ammonium chloride (PDADMAC), polyallyamine (PAM), polyacrylic acid (PAA) and polyethylene oxide (PEO) were selected as candidate amendments for surface properties modification trials. The results indicated that three cationic polyelectrolytes, PDADMAC, PEI and PAM, reduced the (absolute value) zeta potentials of the biosolids surfaces to near zero. The optimal doses for reducing the zeta potentials were found to be 0.008 mg PEI/mg solids; 0.005 mg PAM/mg solids and 0.03 mg PDADMAC/mg solids, respectively. The anionic polyelectrolyte PAA and nonionic polymer PEO were found to be ineffective for modifying the zeta potential of the biosolids. The changes in particle size distributions of the biosolids using the three cationic polyelectrolytes were determined by dynamic light scattering (DLS) measurements. Of the three cationic polyelectrolytes, only PDADMAC was found to increase the biosolids particle size from average size of 340 nm to 3600 nm with 240 min contact time. This indicates the potential for PDADMAC as an amendment for improving the biosolids drying process as it was able to decrease the number of fines and increase the “green” biosolids pellet size.
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Daissè, Gilda. "Interfacial bond behavior of steel-FRCM composites applied to a masonry substrate." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2017.
Find full textAbstract:
In the last decades the theme of structural rehabilitation has acquired great importance and the adoption of composite materials in civil engineering applications has been a turning point in this field. The cement-based matrix of FRCM composites presents many advantages for their application to historical buildings. This dissertation presents a study of the influence of composite bonded length and width on the load response and failure mode. Two types of mortar matrix and two different steel densities were employed. The classical push pull configuration is adopted where fibers are pulled while the masonry block is restrained. Based on the experimental results and through a fracture mechanics approach, the cohesive material laws for mode II was obtained. For the completeness of the work, the characterization of each material involved in the single-lap shear test has been achieved.
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Del, Campo Menoyo Javier. "Compatibilisation of polyimide-silica ceramers and interfacial interactions with carbon fibres in high-temperature matrix composites." Thesis, Loughborough University, 1997. https://dspace.lboro.ac.uk/2134/27080.
Full textAbstract:
When the inorganic domain sizes in a composite are reduced to a level such that a "molecular composite" is formed, the hybrid materials are commonly referred to as "ceramers". Hybrid materials span from inorganically modified organic polymers to inorganic g1asses slightly modified by organic polymers. The incorporation of an inorganic phase into an organic polymer is done almost exclusively by the "sol-gel" process.
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Kang, Narae. "The effect of carbon nanotube/organic semiconductor interfacial area on the performance of organic transistors." Master's thesis, University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5335.
Full textAbstract:
Organic field-effect transistors (OFETs) have attracted tremendous attention due to their flexibility, transparency, easy processiblity and low cost of fabrication. High-performance OFETs are required for their potential applications in the organic electronic devices such as flexible display, integrated circuit, and radiofrequency identification tags. One of the major limiting factors in fabricating high-performance OFET is the large interfacial barrier between metal electrodes and OSC which results in low charge injection from the metal electrodes to OSC. In order to overcome the challenge of low charge injection, carbon nanotubes (CNTs) have been suggested as a promising electrode material for organic electronic devices. In this dissertation, we study the effect of carbon nanotube (CNT) density in CNT electrodes on the performance of organic field effect transistor (OFETs). The devices were fabricated by thermal evaporation of pentacene on the Pd/single walled CNT (SWCNT) electrodes where SWCNTs of different density (0-30/µm) were aligned on Pd using dielectrophoresis (DEP) and cut via oxygen plasma etching to keep the length of nanotube short compared to the channel length. From the electronic transport measurements of 40 devices, we show that the average saturation mobility of the devices increased from 0.02 for zero SWCNT to 0.06, 0.13 and 0.19 cm2/Vs for low (1-5 /µm), medium (10-15 /µm) and high (25-30 /µm) SWCNT density in the electrodes, respectively. The increase is three, six and nine times for low, medium and high density SWCNTs in the electrode compared to the devices that did not contain any SWCNT. In addition, the current on-off ratio and on-current of the devices are increased up to 40 times and 20 times with increasing SWCNT density in the electrodes. Our study shows that although a few nanotubes in the electrode can improve the OFET device performance, significant improvement can be achieved by maximizing SWCNT/OSC interfacial area. The improved OFET performance can be explained due to a reduced barrier height of SWCNT/pentacene interface compared to metal/pentacene interface which provides more efficient charge injection pathways with increased SWCNT/pentacene interfacial area.<br>M.S.<br>Masters<br>Physics<br>Sciences<br>Physics
44
Min, Jie [Verfasser], and Christoph [Akademischer Betreuer] Brabec. "Solution-Processed Small Molecule Bulk Heterojunction Organic Solar Cells: Molecular, Morphological, Interfacial and Device Engineering / Jie Min. Gutachter: Christoph Brabec." Erlangen : Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), 2015. http://d-nb.info/1078406588/34.
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Norlin, Anna. "Investigation of electrochemical properties and performance of stimulation/sensing electrodes for pacemaker applications." Doctoral thesis, Stockholm, 2005. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-176.
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Castro, Pollyana Souza. "Desenvolvimento de microssensores eletroquímicos e aplicações no estudo de processos dinâmicos interfaciais utilizando microscopia eletroquímica de varredura." Universidade de São Paulo, 2015. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-06042016-145742/.
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O trabalho descrito nesta tese mostra de forma detalhada a fabricação e caracterização de diferentes microssensores eletroquímicos os quais têm sido recentemente utilizados como sondas em grupo de técnicas conhecida como Scanning Electrochemical Probe Microscopy (SEPM). Desta forma, a caracterização de superfícies pode ser feita explorando diferentes fenômenos interfaciais relevantes à Ciência. Neste sentido, as interfaces de materiais cristalinos como hidroxiapatita (materiais dentários) e calcita foram o foco de estudo neste trabalho. Assim, diferentes técnicas SEPM foram exploradas no sentido de se obter informações relevantes relacionadas aos processos dentários, como a erosão ácida e hipersensibilidade. Inicialmente, microeletrodos de platina foram desenvolvidos empregando uma metodologia convencional na qual são utilizados microfibras encapsuladas em capilares de vidro. Scanning Electrochemical Microscopy (SECM) no modo amperométrico foi utilizada para obtenção de informações com relação às alterações de topografia do esmalte dentário causadas pelo contato com substâncias ácidas. Adicionalmente, SECM foi empregada no estudo do transporte de espécies eletroativas em amostras de dentina e investigações relacionadas ao bloqueio dos túbulos empregando-se cremes dentais comerciais foram realizadas. A permeação de peróxido de hidrogênio pela dentina também foi estudada. Os resultados de SECM foram comparados com imagens SEM obtidas nas mesmas condições experimentais. Microeletrodos de membrana ionófora íon-seletiva (Ion Selective Microelectrodes-ISMEs) sensíveis a íons cálcio também foram desenvolvidos e caracterizados, com subsequente aplicação em SECM no modo potenciométrico. A dissolução ácida de esmalte bovino (erosão dentária) foi investigada em diferentes valores de pH (2,5; 4,5; 6,8). Além disso, o transporte de íons cálcio através de membranas porosas sintéticas foi avaliado a uma distância tip/substrato de 300µm. Alterações no fluxo de íons cálcio foram correlacionadas em experimentos realizados na presença e ausência de campos magnéticos gerados por nanopartículas de magnetita incorporadas à membrana porosa. Microcristais de calcita facilmente sintetizados pelo método de precipitação foram utilizados como superfície modelo para investigações interfaciais, cujos resultados podem ser correlacionados aos materiais dentários. Desta forma, nanopipetas de vidro preenchidas com eletrólito suporte foram fabricadas e utilizadas como sonda em Scanning Ion Conductance Microscopy (SICM). O mapeamento topográfico de alta resolução espacial da superfície de um microcristal de calcita foi obtido utilizando o modo de varredura hopping mode. Adicionalmente, sondas multifuncionais ISME-SICM também foram desenvolvidas e caracterizadas para investigações simultâneas com relação às alterações topográficas e quantificação de íons cálcio sobre a superfície de um microcristal de calcita. A adição de reagentes ácidos no canal SICM promoveu a dissolução da superfície do microcristal, sendo obtidos dados cinéticos de dissolução. Investigações em meio neutro também foram realizadas utilizando a sonda ISME-SICM. Os resultados experimentais obtidos também foram comparados com aqueles oriundos de simulação computacional.<br>The study reported in this thesis shows in details the fabrication and characterization of different electrochemical microsensors which have been employed as probes in SEPM. Thus, the characterization of surfaces can be performed by exploiting different interfacial phenomena that are relevant to life sciences. In this sense, the interfaces of crystalline materials such as hydroxyapatite (dental materials) and calcite were the focus of this study. Thus, different SEPM techniques were explored in order to obtain relevant information related to dental materials processes such as acid erosion and hypersensitivity. Initially, platinum microelectrodes were developed employing conventional methodology that utilizes microfibers encapsulated in glass capillaries. Amperometric SECM mode was used to obtain information regarding the topography changes of tooth enamel caused by contact with acid chemicals. In addition, SECM was used to study the transport of electroactive species in dentin samples. Investigations related to the treatment of dental hypersensitivity and dental whitening were also evaluated. SECM results were compared with SEM images obtained under the same experimental conditions. Ion-selective microelectrode (ISME) based on the ionophore membrane sensitive to calcium ions were also developed and characterized followed by application in SECM potentiometric mode. The acid dissolution of bovine enamel (dental erosion) was investigated at different pH values (2.5; 4.5; 6.8). In addition, the transport of calcium ions through synthetic porous membranes was evaluated at a tip/substrate distance of 300µm. Changes in calcium ion flux were studied in the presence and absence of magnetic fields generated by magnetite nanoparticles incorporated into the porous membrane. Calcite microcrystals easily synthesized by precipitation method were used as a model of an interfacial surface for investigations which can be correlated to the dental materials. Thus, glass nanopipette filled with supporting electrolyte was fabricated and used as SICM probe. The high resolution topographic mapping of the calcite microcrystal was obtained using hopping mode. Additionally, ISME-SICM multifunction probes were developed and characterized for simultaneous investigations related to the topographical changes and quantification of local calcium ions on the surface of a calcite microcrystal. The addition of acidic reagents in the SICM channel promoted the dissolution of the microcrystal surface and dissolution kinetic data were obtained. Investigations in neutral medium were also studied using the ISME-SICM multifunctional probe. The experimental results were also compared with those obtained by computer simulation.
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Nguyen, Hai Yen. "Modèles pour les ondes interfaciales et leur intégration numérique." Phd thesis, Cachan, Ecole normale supérieure, 2008. https://theses.hal.science/tel-00363790/fr/.
Full textAbstract:
Sous l'effet du rayonnement solaire et/ou de la salinité, l'eau des océans, des rivières et des lacs peut être stratifiée à une certaine profondeur par un changement soudain de densité. La couche la plus légère s'étend au dessus de la couche la plus lourde. Les ondes solitaires apparaissant à l'interface entre ces deux couches influencent les bateaux naviguant dans cette région et peuvent même présenter un danger pour ces bateaux. Elles peuvent également endommager les infrastructures submergées telles que les plateformes pétrolières ainsi que les tunnels sous marins routiers et ferroviaires. Cette thèse propose deux systèmes d'équations susceptibles de modéliser ce type d'ondes, obtenus en utilisant deux méthodes différentes. La propagation et la collision entre deux ondes solitaires sont simulées numériquement. Le filtrage itératif permet d'étudier quantitativement le "run up" ainsi que le déphasage engendrés par ces collisions<br>Under the effect of solar radiation and salinity, water in the oceans, rivers and lakes can be stratified at a certain depth by a sudden change in density. The lighter layer lays over the heavier layer. The solitary waves which appear at the interface between these two layers can have an influence on ships travelling in this region and even present a danger for them. They can also damage submerged engineering constructions such as oil platforms and rail and road tunnels lying on the seabed. This thesis is devoted to two systems of equations capable of modelling this kind of waves. These systems are obtained by using two different methods. The propagation as well as the collision between two solitary waves are simulated numerically. Iterative filtering allows a quantitative study of the run up and phase shift generated by these collisions
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Nguyen, Hai Yen. "Modèles pour les ondes interfaciales et leur intégration numérique." Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2008. http://tel.archives-ouvertes.fr/tel-00363790.
Full textAbstract:
Sous l'effet du rayonnement solaire et/ou de la salinité, l'eau des océans, des rivières et des lacs peut être stratifiée à une certaine profondeur par un changement soudain de densité. La couche la plus légère s'étend au dessus de la couche la plus lourde. Les ondes solitaires apparaissant à l'interface entre ces deux couches influencent les bateaux naviguant dans cette région et peuvent même présenter un danger pour ces bateaux. Elles peuvent également endommager les infrastructures submergées telles que les plateformes pétrolières ainsi que les tunnels sous marins routiers et ferroviaires. Cette thèse propose deux systèmes d'équations susceptibles de modéliser ce type d'ondes, obtenus en utilisant deux méthodes différentes. La propagation et la collision entre deux ondes solitaires sont simulées numériquement. Le filtrage itératif permet d'étudier quantitativement le "run up" ainsi que le déphasage engendrés par ces collisions.
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Macena, Cleidivan Silva. "Emprego da Microscopia Eletroquímica de Varredura SECM na investigação de processos interfaciais visando o desenvolvimento de sensores químicos." Universidade Federal do Maranhão, 2017. http://tedebc.ufma.br:8080/jspui/handle/tede/1733.
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Previous issue date: 2017-02-03<br>Fundação de Amparo à Pesquisa e ao Desenvolvimento Científico e Tecnológico do Maranhão (FAPEMA)<br>The present work demonstrated the potential of Scanning Electrochemical
Microscopy (SECM) in the understanding of enzymatic systems using the enzymes
glucose oxidase (GOx) and the peroxidase of strong root (HRP) as recognition
model. In addition, it evaluated different platforms, such as: Graphene (Gr) and
Carbon Nanotubes (CNTs) in the response of enzymatic systems through
approximation curves and images. In this sense, the reactivity of the GOx and HRP
enzymes was evaluated in the generator / collector mode on an insulating platform.
In addition, the HRP was studied comparatively on graphene platform Gr, CNTs and
on conductive surface. The use of the SECM technique in the investigation of these
systems showed its applicability in the investigation of reactions catalyzed by
enzymes and also showed that CNTs were the best platform for immobilization of
HRP. In addition, it showed the application of SECM in enzymatic systems for the
selective determination of compounds isomers: catechol and hydroquinone.<br>O presente trabalho demostrou a potencialidade da Microscopia Eletroquímica de
Varredura (Scanning Electrochemical Microscopy - SECM) no entendimento de
sistemas enzimáticos usando as enzimas glicose oxidase (GOx) e a peroxidase de
raiz forte (HRP) como modelo de reconhecimento. Ademais, avaliou diferentes
plataformas, como: Grafeno (Gr) e Nanotubos de Carbono (CNTs) na resposta de
sistemas enzimáticos através de curvas de aproximação e imagens. Neste sentido, a
reatividade das enzimas GOx e HRP foi avaliada no modo gerador/coletor sobre
plataforma isolante. Adicionalmente, a HRP foi estudada comparativamente sobre
plataforma de grafeno Gr, CNTs e sobre superfície condutora. O uso da técnica
SECM na investigação desses sistemas mostrou sua aplicabilidade na investigação
de reações catalisadas por enzimas e mostrou ainda que os CNTs fora a melhor
plataforma para imobilização da HRP. Além disso, mostrou a aplicação da SECM em
sistemas enzimáticos para a determinação seletiva de compostos isômeros: catecol
e hidroquinona.
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Du, Preez Louis Jacobus. "Reactive absorption kinetics of CO2 in alcoholic solutions of MEA: fundamental knowledge for determining effective interfacial mass transfer area." Thesis, Stellenbosch : Stellenbosch University, 2014. http://hdl.handle.net/10019.1/86656.
Full textAbstract:
Thesis (PhD)--Stellenbosch University, 2014.<br>ENGLISH ABSTRACT: The reactive absorption rate of CO2 into non-aqueous solvents containing the primary amine,
mono-ethanolamine (MEA) is recognised as a suitable method for measuring the effective
interfacial mass transfer area of separation column internals such as random and structured
packing. Currently, this method is used under conditions where the concentration of MEA in
the liquid film is unaffected by the reaction and the liquid phase reaction is, therefore, assumed
to obey pseudo first order kinetics with respect to CO2. Under pseudo first order conditions,
the effect of surface depletion and renewal rates are not accounted for. Previous research
indicated that the effective area available for mass transfer is also dependent upon the rate of
surface renewal achieved within the liquid film. In order to study the effect of surface depletion
and renewal rates on the effective area, a method utilising a fast reaction with appreciable
depletion of the liquid phase reagent is required.
The homogeneous liquid phase reaction kinetics of CO2 with MEA n-Propanol as alcoholic
solvent was investigated in this study. A novel, in-situ Fourier Transform Infra-Red (FTIR)
method of analysis was developed to collect real time concentration data from reaction
initiation to equilibrium. The reaction was studied in a semi-batch reactor set-up at ambient
conditions (T = 25°C, 30°C and 35°C, P = 1 atm (abs)). The concentration ranges investigated
were [MEA]:[CO2] = 5:1 and 10:1. The concentration range investigated represents conditions
of significant MEA conversion. The reaction kinetic study confirmed the findings of previous research that the reaction of CO2
with MEA is best described by the zwitterion reactive intermediate reaction mechanism. Power
rate law and pseudo steady state hypothesis kinetic models (proposed in literature) were found
to be insufficient at describing the reaction kinetics accurately. Two fundamentally derived rate
expressions (based on the zwitterion reaction mechanism) provided a good quality model fit of
the experimental data for the conditions investigated. The rate constants of the full
fundamental model were independent of concentration and showed an Arrhenius temperature dependence. The shortened fundamental model rate constants showed a possible
concentration dependence, which raises doubt about its applicability.
The specific absorption rates (mol/m2.s) of CO2 into solutions of MEA/n-Propanol (0.2 M and
0.08 M, T = 25°C and 30°C, P = ±103 kPa) were investigated on a wetted wall experimental setup.
The experimental conditions were designed for a fast reaction in the liquid film to occur
with a degree of depletion of MEA in the liquid film. Both interfacial depletion and renewal of
MEA may be considered to occur. The gas phase resistance to mass transfer was determined to
be negligible. An increase in liquid turbulence caused an increase in the specific absorption rate
of CO2 which indicated that an increase in liquid turbulence causes an increase in effective mass
transfer area. Image analysis of the wetted wall gas-liquid interface confirmed the increase in
wave motion on the surface with an increase in liquid turbulence. The increase in wave motion
causes an increase in both interfacial and effective area.
A numerical solution strategy based on a concentration diffusion equation incorporating the
fundamentally derived rate expressions of this study is proposed for calculating the effective
area under conditions where surface depletion and renewal rates are significant. It is
recommended that the reaction kinetics of CO2 with MEA in solvents of varying liquid
properties is determined and the numerical technique proposed in this study used to calculate
effective area from absorption rates into these liquids. From the absorption data an effective
area correlation as a function of liquid properties may be derived in future.<br>AFRIKAANSE OPSOMMING: Die reaktiewe absorpsie van CO2 in nie-waterige oplossings van die primêre amien, monoetanolamien
(MEA) word erken as ‘n geskikte metode om die effektiewe massaoordragsarea
van gepakte skeidingskolomme te bepaal. Tans word die metode gebruik onder vinnige pseudo
eerste orde reaksietoestande met betrekking tot CO2. Die pseudo eersteorde aanname beteken
dat die konsentrasie van MEA in die vloeistoffilm onbeduidend beïnvloed word deur die reaksie
en effektief konstant bly. Onder pseudo eerste orde toestande word oppervlakverarming- en
oppervlakvernuwingseffekte nie in ag geneem nie, juis as gevolg van die konstante konsentrasie
van MEA in die vloeistoffilm. Daar is voorheen bevind dat oppervlakverarming en
oppervlakvernuwing ‘n beduidende invloed het op die beskikbare effektiewe
massaoordragsarea. Hierdie invloed kan slegs bestudeer word met ‘n vinnige reaksie in die
vloeistoffilm wat gepaard gaan met beduidende oppervlakverarming van die vloeistoffase
reagens. Die homogene vloeistoffase reaksiekinetika van CO2 met MEA in die alkohol oplosmiddel, n-
Propanol, is in hierdie studie ondersoek. ‘n Nuwe, in-situ Fourier Transform Infra-Rooi (FTIR)
metode van analiese is ontwikkel in hierdie ondersoek. Die reaksie is ondersoek in ‘n semienkelladings
reaktor met MEA wat gevoer is tot die reaktor om met die opgeloste CO2 te
reageer. Die FTIR metode meet spesiekonsentrasie as ‘n funksie van tyd sodat die
konsentrasieprofiele van CO2, MEA en een van die soutprodukte van die reaksie gebruik kan
word om verskillende reaksiesnelheidsvergelykings te modelleer. Die reaksie is ondersoek
onder matige toestande (T = 25°C, 30°C and 35°C, P = 1 atm (abs)). Die konsentrasiebereik van
die ondersoek was [MEA]:[CO2] = 5:1 en 10:1. Hierdie bereik is spesifiek gebruik sodat daar
beduidende omsetting van MEA kon plaasvind. Die reaksiekinetieka studie het, ter
ondersteuning van bestaande teorie, bevind dat die reaksie van CO2 met MEA in nie-waterige
oplosmiddels soos alkohole, beskyf word deur ‘n zwitterioon reaksiemeganisme. Die bestaande
reaksiesnelheids modelle (eksponensiële wet en pseudo gestadigde toestand hipotese) kon nie
die eksperimentele data met genoegsame akuraatheid beskryf nie. Twee nuwe reaksiesnelheidsvergelykings, afgelei vanaf eerste beginsels en gebaseer op die zwitterioon
meganisme, word voorgestel. Hierdie volle fundamentele model het goeie passings op die
eksperimentele data getoon oor die volledige temperatuur en konsentrasiebereik van hierdie
studie. Die reaksiekonstantes van die fundamentele model was onafhanklik van konsentrasie en
tipe oplosmiddel en het ‘n Arrhenius temperatuurafhanklikheid. Die verkorte fundamentele
model se reaksiekonstantes het ‘n moontlike konsentrasieafhanlikheid gewys. Dit plaas
onsekerheid op die fundamentele basis van hierdie model en kan dus slegs as ‘n eerste
benadering beskou word.
Die spesifieke absorpsietempos (mol/m2.s) van CO2 in MEA/n-Propanol oplossings (0.2 M en
0.08 M MEA, T = 25°C and 30°C, P = ±103 kPa) is ondersoek met ‘n benatte wand (‘wetted wall’)
eksperimentele opstelling. Die eksperimentele toestande is gekies sodat daar ‘n vinnige reaksie
in die vloeistoffilm plaasgevind het, met beide beduidende en nie-beduidende MEA omsetting.
Die doel met hierdie eksperimentele ontwerp was om die invloed van intervlakverarming en
intervlakvernuwing op die spesifieke absorpsietempo te ondersoek. Gas fase weerstand was
nie-beduidend onder die eksperimentele toestande nie. Beide intervlakverarming en
intervlakvernuwing gebeur gelyktydig en is waargeneem vanuit die eksperimentele data. ‘n
Beeldverwerkingstudie van die gas-vloeistof intervlak van die benatte wand het bevind dat daar
‘n toename in golfaksie op die vloeistof oppervlak is vir ‘n toename in vloeistof turbulensie.
Hierdie golfaksie dra by tot oppervlakvernuwing en ‘n toename in effektiewe
massaoordragsarea. ‘n Numeriese metode word voorgestel om die effektiewe area van beide die benatte wand en
gepakte kolomme te bepaal vanaf reaktiewe absorpsietempos. Die metode gebruik die
fundamentele reaksiesnelheidsvergelykings, bepaal in hierdie studie, in a konsentrasie
diffusievergelyking sodat oppervlakverarming en vernuwing in ag geneem kan word. Daar word
voorgestel dat die reaksiekinetika van CO2 met MEA in oplossings met verskillende fisiese
eienskappe (digtheid, oppervlakspanning en viskositeit) bepaal word sodat die numeriese
metode gebruik kan word om ‘n effektiewe area korrelasie as ‘n funksie van hierdie eienskappe
te bepaal.