Дисертації з теми "Particules nanostructurées"
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Desmoulins-Krawiec, Sophie. "Elaboration de particules nanostructurées de nitrures et d'oxynitrures métalliques en milieu fluide supercritique. Etude et modélisation des mécanismes de croissance des particules." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2004. http://tel.archives-ouvertes.fr/tel-00007176.
Desmoulins-Krawiec, Sophie. "Elaboration de particules nanostructurées de nitrures et d'oxynitrures métalliques en milieu fluide supercritique : étude et modélisation des mécanismes de croissance des particules." Bordeaux 1, 2004. http://www.theses.fr/2004BOR12815.
Macroscopic and microscopic supercritical fluids properties can be easily tuned by weak variations of pressure and temperature near their critical point. So they represent an interesting alternative for nanomaterials synthesis. In this study we achieved an explorative research about thermal decomposition of metal precursors to allow a controlled synthesis of metal nitride nanoparticles in supercritical fluid. This decomposition, in supercritical conditions, permits to feed reactive media with metal atoms that react with supercritical ammonia to form nitride nanostructured particles. The aim is to couple within the material, intrinsic properties of nitrides with properties linked to nanoscopic scale. Firstly, we studied experimental parameters effect on material chemical composition and on material morphology in order to define the process potentialities. We showed that the limiting factor for this process is the oxygen presence in the experimental set-up which induces the formation of oxinitride. Next, we focus our researches on nickel nitride, Ni3N. Chemical and structural analysis revealed an insertion of oxygen atoms in the Ni3N structure. Nevertheless, we showed experimental conditions effect on morphology of synthesized material in supercritical ammonia. In addition, a preliminary study on magnetic properties of powders was performed. Finally, a numeric model to predict spherical nanostructured aggregates size evolution versus experimental parameters (residence time, precursor concentration, temperature ) was developed
Nuvoli, Jonathan. "Étude des mécanismes de formation des dépôts de particules appliquée à la filtration THE." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0049.
The filtration of air by fibrous media with high efficiency particulate air (HEPA) is a key point for the safety of sensitive installations. However, filters have a major drawback linked to the increase in their aeraulic resistance during their clogging, which can lead to unbalance the ventilation networks, or even in extreme cases to the rupture of filters and therefore to a loss of containment. In case of fire the filters may be subjected to a large supply of particles or to very clogging particles, causing a rapid increase in their pressure drop. In current pressure drop models used for risk assessment, porosity is a key parameter. Many authors, via simulations, have proposed porosity values for deposits of nanoparticles formed by filtration and have shown, for a given aerosol, a dependence of the porosity as a function of the Peclet number (ratio of the transport mechanisms by convection and diffusion. A specific experimental methodology has been developed in order to study the influence of the porosity of the deposits of the size and morphology of the particles, the physico-chemical characteristics of the particles and the carrier gas (nature, density, viscosity) and operating conditions (filtration rate, pressure). For this study, an experimental bench and a laser measurement device have been developed. This device measures the change in the thickness of the deposit coupled with its deposited mass over time in order to determine the porosity of the deposit. Studies on the deposits of spherical nanoparticles and formed by aggregates have made it possible to define the Stokes number (ratio between the kinetic energy of the particle and the energy dissipated by friction with the fluid) as the most relevant parameter to account for the evolution of the porosity of the deposit. This study led to various correlations allowing the estimation of the porosity of a deposit of pseudo-spherical nanoparticles or nanostructured particles
Chézeau, Laëtitia. "Étude au niveau pulmonaire du profil d’expression de gènes et de protéines chez le rat exposé par inhalation à un aérosol de particules nanostructurées de dioxyde de titane." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0226/document.
Due to the growing use of nanomaterials in various industrial processes, the number of workers potentially exposed is increasing even though the toxicological properties of these compounds are not completely known. Since nanoparticles (NP) may get aerosolized, inhalation represents their main route of occupational exposure. Then, inhalation studies of nanomaterial toxicity in animal models appear to be the most relevant approach to assess their hazards. In this work, we studied the short and long term pulmonary toxicological properties of inhaled titanium dioxide (TiO2) nanostructured aerosol (NSA), using conventional (broncho-alveolar lavage (BAL) analyses, lung and lymph nodes histopathology); and high content molecular toxicological approaches (transcriptomics and proteomics analyses). Fischer 344 rats were exposed to 10 mg/m3 of TiO2 nanostructured aerosol by nose-only inhalation, 6h/day, 5 days/week for 4 weeks. Biological samples were collected immediately and up to 180 post-exposure days. Exposure to TiO2 NSA resulted in a strong acute pulmonary inflammation. This response was characterized by a neutrophil influx, the presence of particle-laden macrophages in the alveolar lumen, as well as overexpression of genes and proteins involved in inflammatory and immune responses, complement and coagulation cascades, oxidative stress. Some overexpressed genes were also involved in DNA damage and fibrosis; and some overexpressed proteins in proteasome and cytoskeleton organization. In the BAL supernatant, the increased level of histones and other neutrophilic extracellular trap (NET) -associated proteins suggests the release of these traps in the alveolar space. This possible NET release occurs in an inflammatory context but in the absence of significant histopathological changes. Very few studies reported this unexpected process related to exposure to nanomaterials. Six months after the end of exposure (long-term response), inflammation had decreased in line with the decrease of titanium lung burden (a surrogate for TiO2 pulmonary deposition), but many genes and proteins remained differentially expressed. The physiopathological consequences of the molecular changes reported here are not fully known, but these results should raise concern about the long-term pulmonary effects of inhaled low toxicity NP such as TiO2. Altogether, this work shows that there is a good relationship between cytological and histopathological changes in one hand and gene as well as protein expression profile modifications in the other hand. However, in some cases transcriptomics or proteomics could be more sensitive than conventional methods to identify new toxicological properties or to better understand the underlying molecular mechanisms of chemicals toxicity. Our study along with others could also be helpful to identify biomarkers of exposure or predict the long-term adverse effects of nanomaterials
Iskandar, Abdo. "Phonon Heat Transport and Photon-phonon Interaction in Nanostructures." Thesis, Troyes, 2018. http://www.theses.fr/2018TROY0010.
In this dissertation, we investigate phonon heat transport and phonon interaction with optical elementary excitations in nanostructures. In the first chapter, we present an introduction to the physics of phonons and optical elementary excitations in nanostructured materials. The second chapter provides a detailed description of the samples growth and fabrication procedures and the various characterization techniques used. In the third chapter, we demonstrate that phonons and photons of different momenta can be confined and interact with each other within the same nanostructure. In the fourth chapter, we present experimental evidence on the change of the phonon spectrum and vibrational properties of a bulk material through phonon hybridization mechanisms. We demonstrate that the phonon spectrum of a bulk material can be altered by hybridization between confined phonon modes in nanostructures introduced on the surface of the material and the underlying bulk phonon modes. Shape and size of the nanostructures made on the surface of the substrate have strong effects on the phonon spectrum of the bulk material itself. In the fifth chapter, we demonstrate that at low temperatures (below 4 K) the nanowire specific heat exhibits a clear contribution from an essentially two-dimensional crystal. We also demonstrate that transitions from specular to diffusive elastic transmission and then from diffusive elastic to diffusive inelastic transmission occur at the interface between nanowires and a bulk substrate as temperature increases. Perspectives include the control of bulk material thermal properties via surface nanostructuring
Ly, Aboubakry. "Effet Seebeck à l’échelle nanométrique de nanostructures chaudes." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0010/document.
The aim of this work is to study the nanoscale Seebeck effect at hot nanostructures. At first, we study the thermo-electrophoresis self-propulsion mechanism for a heated metal capped Janus colloid. The self-propulsion mechanism is mainly induced by the electrolyte Seebeck effect or thermoelectric effect. This effect takes its origin from the separation of charges occurring while a temperature gradient is present in a electrolyte solution: A strong absorption of laser light by the metal side of the particle creates a temperature gradient which in turn acts on ion-species (positive and negative) and drives them to the hot or the cold region. This motion of ion results in a dipolar electric field which, close to the particle, depends strongly on the surface properties. The change of behavior of the electric field at the insulating or conducting surface does not affect the velocity of the particle. At second, we study the effect of hydrodynamic interactions and counterion condensation in thermophoresis for DNA polymer. As the main result, the thermophoretic mobility shows, in function of the chain length, a non-monotonuous behavior and consists of two contributions induced by the dominant driving forces which are the thermally induced permittivity-gradient and the electrolyte Seebeck effect. At the end, we compare our theoretical result with recent experiment on single-stranded DNA
Dems, Dounia. "Nanostructuration de particules de silice et élaboration de biomatériaux composites." Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS373.
This work describes the design of tunable biomaterials for tissue engineering. The composite approach provides numerous advantages to enhance cell adhesion and control bioactivity by complying both with structural and functional requirements. The host matrix, made from a natural macromolecule (collagen), or from synthetic supramolecular polymers (peptide amphiphiles), provides a suitable structural environment to the cells and can also display intrinsic biochemical cues to influence cell behavior. Functionalized silica nanoparticles can be added to be used as platforms either to further tune the architecture of the scaffold or display additional bioactive ligands. The combination of peptide amphiphiles with such nanoparticles led to composite biomaterials with high modularity allowing to compare different displays of one bioactive epitope and the simultaneous grafting of two epitopes known to work in a distance-dependent manner. The next step was to achieve the control of the spatial organization of several functions on the surface of a single nanoparticle. We have developed an original and challenging strategy based on the synthesis of self-assembling alkoxysilane precursors that could form pre-organized domains to be transferred at the silica nanoparticle surface to create patches. A large library of mono- and bifunctional particles were prepared that were incorporated in collagen-based threads evaluated in a model of peripheral nerve regeneration. Finally, we have elaborated thin porous scaffolds by electrospinning collagen in non-denaturing conditions that should allow to improve the cells access to the functional nanoparticles
Jasiak, Rafal. "Ultrafast electron dynamics and decoherence in metallic nanostructures." Strasbourg, 2011. http://www.theses.fr/2011STRA6040.
The ultrafast electron dynamics in thin metal films was studied numerically using both a semiclassical model (Vlasov-Poisson) and a fully quantum approach based on the Wigner equation. For large excitation energies, the quantum and classical dynamics are virtually identical, whereas they diverge below a certain threshold, roughly equal to the plasmon energy. This is a clear signature of a quantum-mechanical effect, which should be observable in standard pump-probe experiments on thin metal films. For longer timescales, the electron dynamics becomes dissipative, as the electrons exchange energy incoherently with the ion lattice. A classical relaxation time and a quantum decoherence time were shown to emerge naturally from the simulations. These time scales are in good agreement with phenomenological estimates based on the two-temperature model, and correctly reproduce the main features observed in experiments on small sodium clusters
Chenal, Marion. "Particules cœur-écorce par polymérisation raft en émulsion pour des matériaux nanostructurés sans solvants." Paris 6, 2013. http://www.theses.fr/2013PA066303.
The aim of this project was to improve the mechanical properties of latex-based films, which represent an attractive alternative to solvent-based formulations in order to reduce volatile organic compounds emissions and move towards green chemistry. A strategy based on core-shell particles was chosen. Aqueous emulsion polymerization of n-butyl acrylate was performed in batch conditions without surfactants using a poly(acrylic acid)-trithiocarbonate macroRAFT agent to control the polymerization and stabilize the emulsion. The resulting well-defined amphiphilic PAA-b-PBA diblock copolymers self-assemble during synthesis to yield highly stable core-shell particles with an extremely thin PAA shell. After drying the aqueous dispersion, tough and transparent films were obtained. As they do not contain surfactants, the films remain transparent even after immersion in water. Rheology showed that the films are both stiff and ductile, thanks to the nanostructured but very low volume fraction (less than 3 wt%) of PAA in the soft PBA. Microscopy and SAXS experiments proved that the PAA shells form a percolating network throughout the film, which is responsible for the enhanced mechanical properties. Compared to conventional core-shell based films, this approach affords for the first time a route to a thin percolating honeycomb nanostructure with both a sharp and a strong interface between the two phases. The versatility of the synthetic procedure opens perspectives for a large range of functional materials. For example, the molar mass of the PAA or the PBA block can be varied, or cross-linking can be introduced in the core and/or the shell of the particles
Benghorieb, Soulef. "Modélisation des modifications des propriétés optiques de nouveaux matériaux nanostructurés par des particules métalliques." Thesis, Saint-Etienne, 2011. http://www.theses.fr/2011STET4002.
This thesis is devoted to modeling of the optical properties of nanostructured dielectrics by metal particles. We interested in two aspects of the problem: the determination of effective index and field distribution of plasmon nanoparticles dispersed in such media. We have developed two numerical approaches. The first is devoted to the simulation of real and imaginary parts of the effective index of heterogeneous medium. In order to compare experience and theory, we have proposed an experimental approach to measure the effective refractive index of colloidal solutions containing metal or semiconductor nanospheres. The second aspect deals with the method of extraction of the field plasmon on the surface of metal nanosphere when it is excited by electromagnetic plane wave. The calculated effective index and field plasmon are done in function of characteristic parameters of nanoparticles and host matrix
Deplace, Fanny. "Adhésifs nanostructurés en voie émulsion." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2008. http://pastel.archives-ouvertes.fr/pastel-00004244.
Deplace, Fanny. "Waterborne nanostructured adhesives." Paris 6, 2008. http://www.theses.fr/2008PA066035.
Pessey, Vincent. "Elaboration de poudres inorganiques nanostructurées en milieux fluides supercritiques." Phd thesis, Université Sciences et Technologies - Bordeaux I, 2000. http://tel.archives-ouvertes.fr/tel-00003497.
Pujol, Ollivier. "Étude par microscopie électronique de particules nanostructurées d'oxalate de cobalt précipitées en milieu aqueux /." [S.l.] : [s.n.], 2004. http://library.epfl.ch/theses/?nr=2988.
El, Hamzaoui Hicham. "Préparation et caractérisation de matériaux hybrides organostanniques nanostructures." Bordeaux 1, 2006. http://www.theses.fr/2006BOR13237.
Gadalla, Abdalla Atef. "Laser applications to the characterization of semiconductor nanostructures : coherent control and spin dynamics of elementary electronical excitations." Strasbourg, 2010. http://www.theses.fr/2010STRA6078.
We study the population dynamics and optical orientation of excited electronic states in semiconductors thin films and nanostructures. One subject concems the phthalocyanine (Pc), an organic compound semiconductor, in thin film fonn. A second work studies the spin relaxation dynamics of free excitons in a narrow GaN/AIGaN quantum weIl. We apply a temporally and spectrally resolved femtosecond (fs) pumpand-probe technique using a tuneable Ti: Sapphire laser source. We measured the differential transmission rate (,dT(I)/T) as a function of time delay (t) between the pump and probe pulses for the Pc samples while for the GaN/AI GaN QW we have measured the differential reflectivity spectra (tJR(t)/R) for the two different probe helicities simultaneously at different pump-probe delays
Silly, Fabien. "Corrélations spatiales et temporalles de l'émision de photons induite par STM sur des surfaces nanostructurées." Paris 6, 2001. http://www.theses.fr/2001PA066565.
Schaer, Éric. "Conception d'un procédé pour la production de microparticules filtrables et redispersables." Vandoeuvre-les-Nancy, INPL, 1997. http://docnum.univ-lorraine.fr/public/INPL_T_1997_SCHAER_E.pdf.
Lachevre, Valérie. "Propriétés d'alliages micro et nanostructurés : développement de leurs caractéristiques ferromagnétiques pour l'absorption des ondes électromagnétiques." Grenoble 1, 1999. http://www.theses.fr/1999GRE10062.
Garnier, Jérôme. "Elaboration de latex nanostructurés à base de poly(chlorure de vinylidène) par polymérisation en émulsion." Thesis, Montpellier, Ecole nationale supérieure de chimie, 2012. http://www.theses.fr/2012ENCM0011.
Food and pharmaceutical packages should nowadays fulfill a wide range of requirements : not only should they preserve the packed products from external polluting agents, but they must also be innocuous, more energy-efficient and disposable. Barrier polymers have enabled to meet these criteria, by offering alternatives to more energy-consuming and heavier materials like glass or metals, while maintaining a low permeability to water and/or oxygen. Among the large variety of barrier polymers, poly(vinylidene chloride) (PVDC) copolymers provide a more complete protection to external contaminants, due to their extremely low permeabilities towards water and oxygen. Nonetheless, PVDC films still suffer from limitations as far as their thermal and UV stabilities are concerned. This effect is even more pronounced in the case of films obtained from latexes, due to the presence of higher amounts of additives that could take part in the polymer degradation. Therefore, the synthesis of PVDC-based latexes for use as waterborne barrier films with improved thermal and UV stabilities are of great importance. PVDC-based composite latexes were first synthesized from epoxy-functionalized seed latexes in order to enhance the polymer thermal stability. Given that hydrogen chloride displays an indirect catalytic effect on the polymer degradation, epoxy groups were indeed expected to act as thermal stabilizers by scavenging the HCl released by the polymer under thermal stress. In a first step, epoxy-functionalized seed latexes were synthesized via the emulsion copolymerization of glycidyl methacrylate (GMA) and butyl methacrylate (BMA). In a second step, the seeded emulsion copolymerization of vinylidene chloride and methyl acrylate was carried out in the presence of poly(GMA-co-BMA) seed latexes. Thermogravimetric analyses carried out on the resulting composite samples evidenced the thermal stabilization provided by epoxy groups. The second part of the project focused on the synthesis of cerium oxide-based hybrid latexes so as to improve the stability of PVDC to UV radiation. Cerium oxide (CeO2) nanoparticles are indeed very attractive as UV-stabilizers due to their high absorption of radiation in the UV range and a low photocatalytic activity. However, due to the intrinsic incompatibility between inorganic and polymer phases, the synthesis of inorganic-organic hybrid latexes often requires a preliminary step of modification of the mineral particles surface. The grafting of alkoxysilanes onto nanoceria was first attempted in order to promote the polymerization reaction at the surface of the inorganic particles. Cryo-Transmission Electron Microscopy (cryo-TEM) observations of hybrid latexes obtained via this route showed that this strategy was unsuccessful at improving the compatibility between the inorganic and polymer phases. Amphiphatic macro-RAFT agents were finally considered as reactive compatibilizing agents to direct the polymerization towards the cerium oxide surface. RAFT oligomers were first obtained by co- or terpolymerization reactions in the presence of a RAFT controlling agent. After characterizing the adsorption of amphiphatic macro-RAFT agents at the surface of nanoceria, surface-modified cerium oxide particles were then engaged in reactions of emulsion polymerization reactions. In most cases, cryo-TEM observations carried out on the resulting latexes confirmed the efficiency of the amphiphatic macro-RAFT agent route for the synthesis of hybrid structures. Therefore this route appeared so far to be the most promising for the synthesis of CeO2/PVDC hybrid latexes for use as waterborne barrier films with improved UV-stability
Dos, Santos Matos Ana Paula. "Development of micro and nanostructured systems for cutaneous leishmaniasis treatment." Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2018. http://www.theses.fr/2018EMAC0021.
Leishmaniasis is a neglected disease caused by protozoan parasites of the Leishmania genus and affects millions of people in several countries. The current treatment for cutaneous leishmaniasis (CL) has many side effects. Based on this scenario, there is an intensive search of new formulations and the study of different routes mainly for CL treatment. In this way, micro and nanotechnology are important technologies, which may be useful for modulation release profile of the drugs improving its bioavailability. One the most investigate drug for CL treatment is paromomycin (PM), an aminoglycoside antibiotic administered by the intravenous and topical route. Another important drug is intravenous amphotericin B (AmB), a macrolide antibiotic used as second-choice treatment. The aims of this study were to develop an oil-water (O/W) nanoemulsion containing AmB for topical administration and spray-dried polymeric microparticles containing PM for intralesional administration for CL treatment. Formulations were characterized mainly in terms of size and morphology of particles or oil droplets, thermal properties, drug content, stability and release behavior. Biological activity was evaluated by in vitro safety in macrophages and antileishmanial activity against Leishmania amazonensis promastigotes. O/W nanoemulsions containing AmB, were characterized by oil droplets of around 50 nm in size, with polydispersity index lower than 0.5, and drug content of 0.5 mg/mL. Nanoemulsions showed slow and controlled AmB release kinetic, low skin permeation. However, these formulations were cytotoxicity with good antileishmanial activity. Indeed, the best formulation showed stability until 365 days, but required stored in cold chain. For PM-loaded polymeric microparticles, different carriers were investigated (PLGA alone or a mixture of PLGA-PLA). It was found that PM release kinetic was influenced by the carrier composition, with a slow release for the blend of polymers. The investigated formulations were non-toxic and revealed good antileishmanial activity. Therefore, the OW-AmB loaded nanoemulsions and the polymeric-PM loaded microparticles presented interesting results as novel alternatives for CL treatment. Nevertheless, more studies are required for their optimization as antileishmanial activity against L. amazonensis amastigotes and, further, in vivo studies in BALB/c mice
Houmed, adabo Ali. "Greffage chimique et électrochimique de nanoparticules d'or : vers des capteurs plus sensibles." Thesis, Besançon, 2014. http://www.theses.fr/2014BESA2065/document.
Rhomari, Mohammed. "Phosphates de zirconium et d'étain pontés par des fragments de silice : nouvelles matrices pour la réalisation de nanostructures." Montpellier 2, 1992. http://www.theses.fr/1992MON20282.
Nehache, Sabrina. "Elaboration de membranes à partir d’assemblages nano-organisés de particules polymères." Thesis, Montpellier, 2015. http://www.theses.fr/2015MONTS080.
This thesis deals with the development of nano-structured thin nano-porous films from polymeric particles (ABA, AB copolymers and polymer/MOF) in perspective of developing new innovative membranes. The obtained films have been used as water filtration or gas separation membranes. Regarding the ABA triblock copolymer made of polystyrene-sodium polystyrene sulfonate-polystyrene (PS-PNaSS-PS) it was shown that nano-porous films with various structures (honeycombs, isoporous and compact), could be made. The morphologies of these nanoparticles could be tuned depending on the hydrophobic and hydrophilic block ratios, solvent composition and concentration. Concerning the study of the diblock copolymer, monodisperse spherical nanoparticles of PDMAEMA-b-PMMA were made in situ (PISA) using a coumarin functionalized RAFT chain transfer agent in ethanol. Upon UV irradiation, these particles could be connected reversibly through the dimerization of the coumarin function present on their corona. The resulting thin films had dynamic characteristic due to the establishment of the reversible formation of the cyclobutane ring under UV irradiation. This manuscript was concluded by preparation of Mix Matrix Membranes (MMMs) from mixture of polyimide (Matrimid®) and ZIF-8 nanoparticles to be used as gas permeation membrane. The employed new approach in this study led to formation of perfectly homogeneous membranes with improved cohesion between the MOF structure and the polymeric matrix. A better separation of CH4 / CO2 gas mixtures was achieved using the prepared MMM
Lallet, François. "Eudes numériques et expérimentales de systèmes auto-organisés à différentes échelles : exemples d'îlots YSZ nanométriques et de particules de diamant micrométriques." Limoges, 2008. https://aurore.unilim.fr/theses/nxfile/default/e5f5f286-7eb4-4302-9040-cffeb5de3823/blobholder:0/2008LIMO4006.pdf.
In a first part, we focus on the {YSZ||(0001)α-Al2O3} {flayer||substrateg} system synthesized via sol-gel route for which thermal treatments induce the formation of top-at epitaxial nanometric YSZ islands (interfaces (1) and (2) ; at substrate) or rounded (interface (3) ; rough substrate). We propose a physical model at the atomic scale and ab initio computations in order to quantify and compare their corresponding interface energies. The second part introduces a physical model at the nanometric scale and a classical Monte-Carlo algorithm to describe the islanding process, during thermal treatment, of thin solid films synthesized by sol-gel process. This part highlight the previous study because we demonstrate the higher stability of interface (3) with regard to interfaces (1) and (2) on a rough susbtrate. Then we describe, through an analogous strategy, the formation of islands for thin solid films synthesized by PVD-CVD processes illustrated by the {Ge||Si} system. Finally, a physical model and a classical molecular dynamic algorithm are introduced to simulate the self-organisation process of micrometric diamond particules embedded in a liquid film dried horizontally on an substrate. The particles are submitted to lateral attractive capillary forces and friction forces with a substrate either at or indented. Experiments demonstrate a much more efficient aggregation on the rough parts of an indented substrate. The model demonstrates how critical are the friction forces in the interpretation of this phenomena
Lages, José. "Phase de bi-particules localisées par interaction attractive dans un milieu aléatoire." Phd thesis, Université Paul Sabatier - Toulouse III, 2001. http://tel.archives-ouvertes.fr/tel-00008016.
Bau, Sébastien. "Étude des moyens de la surface des aérosols ultrafins pour l'évaluation de l'exposition professionnelle." Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL095N/document.
This work aims at improving knowledge on ultrafine aerosols surface-area measurement. Indeed, the development of nanotechnologies may lead to occupational exposure to airborne nanostructured particles, which involves a new prevention issue. There is currently no consensus concerning what parameter (mass, surface-area, number) should be measured. However, surface-area could be a relevant metric, since it leads to a satisfying correlation with biological effects when nanostructured particles are inhaled. Hence, an original theoretical work was performed to position the parameter of surface-area in relation to other aerosol characteristics. To investigate measurement techniques of nanostructured aerosols surface-area, the experimental facility CAIMAN (ChAracterization of Instruments for the Measurement of Aerosols of Nanoparticles) was designed and built. Within CAIMAN, it is possible to produce nanostructured aerosols with varying and controlled properties (size, concentration, chemical nature, morphology, state-of-charge), stable and reproducible in time. The generated aerosols were used to experimentally characterize the response of the instruments in study (NSAM & AeroTrak 9000 TSI, LQ1-DC Matter Engineering). The response functions measured with monodisperse aerosols show a good agreement with the corresponding theoretical curves in a large size range, from 15 to 520 nm. Furthermore, hypotheses have been formulated to explain the reasonable biases observed when measuring polydisperse aerosols
Etchart-Salas, Ramuntxo. "Projection par plasma d’arc de particules submicroniques en suspension : approche expérimentale et analytique des phénomènes impliqués dans la reproductibilité et la qualité des dépôts." Limoges, 2007. https://aurore.unilim.fr/theses/nxfile/default/648caa0a-0d53-4f45-8323-e7a1f0a5609b/blobholder:0/2007LIMO4058.pdf.
Nanostructured coatings exhibits unique properties in various applications, such as aeronautics, energy, automotive, etc. . . Suspension Plasma Spraying (SPS) seems to be a promising technique to elaborate finely structured coatings with low thickness (between 5 µm to 10 µm). Nevertheless, SPS parameters which lead to control the microstructure of the deposit are not yet clearly identify, particularly for the injection of suspension. It has been shown that injection and fragmentation of the suspension into the plasma jet plays a key role in their further heat treatment. The injection of the suspension has been observed with a fast shutter camera coupled with a laser flash and triggered by a defined instantaneous voltage level of the plasma torch. Hence, the trajectories and fragmentations of the drops can be observed and correlated to an instantaneous plasma state. A particular attention is paid to the treatment of suspension jet or drops according to the importance of voltage fluctuations (linked to those of arc root) and depending on the different spray parameters such as the plasma forming gas mixture and the suspension momentum. A significant difference has been highlighted between argon-hydrogen and argon-helium plasma, mainly due to their strong fluctuation particularities. The heterogeneity of drops treatment using argon-hydrogen plasma is due to arc voltage fluctuations, and the enhancement of the coating porosity has been observed in this case. The stabilization of the interaction plasma jet-suspension increases when using plasmas with low arc voltage instabilities like Ar-He. The reduction of the drops dispersion into the plasma flow decreases the rate of unmellted particles into the coating and thus it porosity. These works have also allowed the formation of zirconia coatings with low thicknesses (~10 µm) and dense structure (~ 4% of porosity). Different dense deposits have been elaborated using either argon-hydrogen or argon-helium plasma, when the interaction plasma-suspension is controlled and adapted
D', Abzac François Xavier. "Effets d'une impulsion laser infra-rouge femtoseconde sur les micro-nanostructures des mineraux implications pour les analyses in-situ pa LA-ICP-MS." Phd thesis, Université Paul Sabatier - Toulouse III, 2010. http://tel.archives-ouvertes.fr/tel-00583820.
Abzac, François-Xavier d'. "Effets d'une impulsion laser Infra-rouge femtoseconde sur les micro-nanostructures des minéraux : implications pour les analyses in-situ par LA-ICP-MS." Toulouse 3, 2010. http://thesesups.ups-tlse.fr/1119/.
Infra Red femtosecond laser ablation coupled to Mass Spectrometry is a powerful tool for in-situ analysis of geological samples. Nevertheless, implications linked to this type of ablation are still not well defined. Transmission Electron Microscopy (TEM) coupled to Focused Ion Beam milling (FIB) allows direct characterization of ablation damage and particles. Thus, IR-femtosecond laser ablation can be considered as stoechiometric and mainly photo-mechanical. Particles are generated by coalescence and agglomeration of condensates in the laser induced plasma. Chemical segregation of elements noticed on measurements is then confined to these processes, themselves dependant on the target composition. The potential of analytical improvement is substantial, in terms of ablation settings and conception of laser systems dedicated to LA-ICP-MS
Mevel, Benoît. "Propriétés structurales, magnétiques et de transport d'alliages hétérogènes Co(x)Ag(1-x) et Ni(x)Ag(1-x)." Université Joseph Fourier (Grenoble), 1997. http://www.theses.fr/1997GRE10071.
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Rabanel, Jean-Michel. "Nanostructure des particules polymériques : aspects physiques, chimiques et biologiques." Thèse, 2015. http://hdl.handle.net/1866/13810.
The goal set to nanotechnologies applied to pharmaceutical sciences is to improve drug delivery and benefits with the help of nanometer-sized vehicles. At this time different types of drug carriers had been proposed. Amongst them, block copolymer nanoparticles (NP) have been designed to allow, at the same time, efficient drug encapsulation and provide surface properties (hydrophilic layer) to the NP which are necessary for its interactions with biological systems by preventing the opsonisation and the subsequent recognition by the mononuclear macrophage system (MPS) and the rapid elimination of the drug carrier. The most prominent polymer architecture in drug delivery application is the linear di-block copolymer architecture, such as poly(ethylene glycol) blocks (PEG) linked to a polyester hydrophobic chain. PEG is the gold standard to add a hydrophilic corona to drug carrier’s surface, but its efficacy is directly linked to its surface organization and surface densities. In spite of limited success of diblock at the clinical stage, few studies have been devoted to other type of architecture such as comb-like copolymers, either for the exploration of new synthesis routes or for the characterization of particles prepared from alternative architecture polymers. We attempted in preamble of this work to define more closely the conceptual and technical framework allowing quantitative determination of PEG surface densities. This review work has been used in the experimental work to define the characterization methods. Several synthesis strategies have been developed for the preparation of comb copolymers in this work. All strategies are based on random copolymerization of dilactide with small epoxy molecules with a pendant group suitable for subsequent PEG grafting, yielding a polyester-co-ether backbone. In a second step, PEG chains have been grafted on available pendant groups (alcohol groups or alkyne) to produce the final comb copolymers. In the first part of the experimental work, esterification reaction by acylation and coupling (the Steglish reaction) allowed the preparation of a first comb-like copolymer library with PEG content varying from 5 to 50 % (w/w). The number of PEG chains (PEG grafting density) was varying while the lengths of the PEG chains and the hydrophobic PLA backbone were kept constant. The library of comb-like polymers was used to prepare nanocarriers with dense PEG brushes at their surface, stability in suspension, and resistance to protein adsorption. The structural properties of nanoparticles (NPs) produced from these polymers by a surfactant-free method were assessed by DLS, zeta potential, and TEM and were found to be controlled by the amount of PEG present in the polymers. A critical transition from a solid NP structure to a soft particle with either a “micelle-like” or “polymer nano-aggregate” structure was observed when the PEG content was between 15 to 25% w/w. This structural transition was found to have a profound impact on the size of the NPs, their surface charge, their stability in suspension in presence of salts as well as on the binding of proteins to the surface of the NPs. The arrangement of the PEG-g-PLA chains at the surface of the NPs was investigated by 1H NMR and X-ray photoelectron spectroscopy (XPS). NMR results confirmed that the PEG chains were mostly segregated at the NP surface. Moreover, XPS and NMR allowed the quantification of the PEG chain coverage density at the surface of the solid NPs. Concordance of the results between the two methods was found to be remarkable. Physical-chemical properties of the NPs such as resistance to aggregation in saline environment as well as anti-fouling efficacy, assessed by isothermal titration calorimetry (ITC), were related to the PEG surface density and ultimately to polymer architecture. In the second part of this work, grafting of PEG chains on a polyester-co-ether backbone was directly performed using cyclo-addition of PEG azide on pendant alkyne groups. The new strategy was designed to understand the contribution of PEG chains grafted on PLA backbone ends. The new polymer library was composed of PEG-g-PLA with different PEG grafting densities and PEG molecular weights (750, 2000 and 5000 D). PEG chain grafting could only take place on pendant groups with this approach. NPs were produced by different methods of nanoprecipitation, including “flash nanoprecipitation” and microfluidic technology. Some formulation variables such as polymer concentration and speed of mixing were studied in order to observe their effects on NP surface characteristics. Unlike for the first copolymer library, here the NPs size and zeta potential were found to not be much affected by the PEG content (% w/w in polymer). Sizes were also not affected by the PEG chains length. TEM images show round shaped object and as expected sizes were found to decrease with polymer concentration in the organic phase and with a decrease in mixing time of the two phases (for flash nanoprecipitation and microfluidic technology). PEG chain surface densities were assessed by quantitative 1H NMR and XPS. In the third experimental part, we explored the role of polymer architecture on drug encapsulation and release of curcumin from NPs. Curcumin has been chosen as a model with a view to develop a delivery platform to treat diseases involving oxidative stress affecting the CNS. As previously observed with blank NPs, a sharp decrease in curcumin-loaded NP size and morphology change occurred between 15 to 20 % w/w of PEG. Drug loading, Drug loading efficiency and the diffusion coefficients of curcumin in NPs are showing a dependence over the polymer architecture. NPs did not present any significant toxicity when tested in vitro on a neuronal cell line. Moreover, the ability of NPs carrying curcumin to prevent oxidative stress was evidenced and linked to polymer architecture and NPs organization. In a nutshell, our study showed the intimate relationship between the polymer architecture and the biophysical properties of the resulting NPs and sheds light on new approaches to design efficient NP-based drug carriers. The results obtained lead us to propose PEG-g-PLA comb architecture copolymers for nanomedecine development as an alternative to the predominant polyester-PEG diblock polymers.
Swain, Ipsita Priyadarshini. "Evolution of Porosity and Nanostructure in Preceramic Polymer Derived Nanoporous Particulates." Thesis, 2021. http://ethesis.nitrkl.ac.in/10397/1/2021_PhD_IPSwain_514CR6004_Evolution.pdf.