The separation of submicron particles suspended in gaseous flows is a problem of great importance and is the subject of sustained research efforts. This is motivated by several challenges presented by modern science and technology requiring high separation efficiencies for submicron particles.Continuous acoustic particles separation is a novel technique based on the acoustophoresis phenomenon, in which a particle within an acoustic field is manipulated using acoustic forces on its surface. This technique has the potential to overcome some of the limitations of common techniques for the separation of submicron particles, as well as performing advanced tasks such as sorting particles according to their size or density.In this thesis, the separation of submicron solid particles suspended in air is investigated experimentally, with a focus on the effect of key design parameters (acoustic, flow, geometry) on the efficiency of the process. A simple method based on laser light scattering was also used to provide qualitative information on the particle number density as a function of position in the channel. This technique allowed to quickly investigate the effect of a wide range of parameters on the acoustic separation efficiency including the pressure amplitude, the frequency of the standing wave, the average flow velocity and the parallelism of the channel walls.   The results demonstrate conclusively that acoustic manipulation is possible for submicron particles and that the acoustic force scales following the trends expected from theoretical models developed in the continuum regime. From the size of the particles used it however follows that the observed separation is the result of transition regime acoustophoresis, with a Knudsen number on the order of 0.2. / <p>QC 20150522</p>

Made available in DSpace on 2014-12-17T15:01:32Z (GMT). No. of bitstreams: 1 AndreACP_DISSERT.pdf: 6190808 bytes, checksum: 21a983a9627b562fbe33e41da8ebdfd8 (MD5) Previous issue date: 2013-08-09 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Polymer particles in the nanometer range are of fundamental interest today, especially when used as carrier systems in the controlled release of drugs, cosmetics and nutraceuticals, as well as in coating materials with magnetic properties. The main objective of the present study concerns the production of submicron particles of poly (methyl methacrylate) (PMMA) by crystallization of a polymer solution by thermally controlled cooling. In this work, PMMA solutions in ethanol and 1-propanol were prepared at different concentrations (1% to 5% by weight) and crystallized at different cooling rates (0.2 to 0.8 ? C / min) controlled linearly. Analysis of particle size distribution (DLS / CILAS) and scanning electron microscopy (SEM) were performed in order to evaluate the morphological characteristics of the produced particles. The results demonstrated that it is possible to obtain submicron polymer perfectly spherical particles using the technique discussed in this study. It was also observed that, depending on the cooling rate and the concentration of the polymer solution, it is possible to achieve high yield in the formation of submicron particles. In addition, preliminary tests were performed in order to verify the ability of this technique to form particulated carrier material with magnetic properties. The results showed that the developed technique can be an interesting alternative to obtain polymer particles with magnetic properties / Part?culas polim?ricas formadas em escala nanom?trica s?o de fundamental interesse atualmente, principalmente quando utilizadas como sistemas carreadores na libera??o controlada de f?rmacos, cosm?ticos e nutrac?uticos, al?m do interesse pr?tico no recobrimento de materiais com propriedades magn?ticas. O principal objetivo do presente estudo diz respeito ? produ??o de part?culas submicrom?tricas de poli(metacrilato de metila) (PMMA) atrav?s da t?cnica de cristaliza??o de uma solu??o polim?rica por resfriamento controlado termicamente, segundo um perfil de taxa linear de resfriamento. Neste trabalho, solu??es de PMMA em etanol e 1-propanol foram preparadas em diferentes concentra??es (1% a 5% em massa) e cristalizadas em diferentes taxas de resfriamento (0,2 a 0,8 ?C/min) controladas linearmente. An?lises de distribui??o de part?culas (DLS/CILAS) e microscopia eletr?nica de varredura (MEV) foram realizadas com o intuito de avaliar as caracter?sticas morfol?gicas das part?culas formadas. Os resultados demonstraram que ? poss?vel obter part?culas polim?ricas submicrom?tricas com morfologia perfeitamente esf?rica utilizando a t?cnica abordada no presente estudo. Observou-se tamb?m que, a depender da taxa de resfriamento e da concentra??o da solu??o polim?rica, ? poss?vel ter alto rendimento na forma??o de part?culas submicrom?tricas. Adicionalmente, foram realizados testes preliminares com o prop?sito de verificar a capacidade desta t?cnica em formar part?culas carreadoras de materiais com propriedades magn?ticas. Os resultados permitiram concluir que a t?cnica estudada pode ser uma alternativa interessante na obten??o de part?culas polim?ricas com propriedades magn?ticas

Crankcase ventilation contributes significantly to diesel engine particulate emissions. Future regulations will not only limit the mass of particulate matter, but also the number of particles. Controlling the source of crankcase emissions is critical to meeting the perennial legislation. Deficiency in the understanding of crankcase emissions generation and the contribution of lubricating oil has been addressed in detail by the experimental study presented in this thesis. A plethora of high speed laser optical diagnostics techniques have been employed to deduce the main mechanisms of crankcase oil aerosol generation. Novel images have captured oil atomisation and passive oil distribution around the crankcase of an optically accessed, motored, four cylinder, off highway, heavy duty, diesel engine. Rayleigh type ligament breakup of oil films present on the surface of dynamic components, most notably the crankshaft, camshaft and valve rockers generated oil drops below 10 micrometers. Data illustrated not only crankcase oil aerosol generation at source, but it has provided valuable information on methods to control oil aerosol generation and improve oil circuit efficiency. The feasibility of utilising computational fluid dynamics to predict crankcase oil aerosol generation has been successfully assessed using the experimental data. Particle sampling has characterised the crankcase emissions from both a fired and motored diesel engine crankcase. The evolution of submicron crankcase particles down to 5 nm has been recorded from both engines, including the isolated contribution of engine oil, at a wide range of engine test points. Results have provided constructive insight into the generation and control of this complex emission. The main mechanism of crankcase oil aerosol generation was found to be crankshaft oil atomisation. This atomisation process has been analysed in detail, involving high speed imaging of primary and satellite drop generation and high speed digital particle image velocity of the crankshaft air flow. A promising mechanism of regulating and controlling crankcase oil aerosol emissions at source has been studied experimentally.

La détection d'agents biologiques dans l'air ambiant est devenue un enjeu majeur notamment en environnement hospitalier et dans la protection contre le bioterrorisme. Dans ce contexte, la miniaturisation des dispositifs d'analyse permet d'envisager leur utilisation directement sur la zone d'étude. Afin d'obtenir un échantillon concentré et représentatif, la filtration de l'air reste cependant un point délicat. Parmi les différents principes exploitables pour la collecte de particules aéroportées, l'emploi des forces électriques semble être prometteur pour améliorer les performances des dispositifs qui se trouvent généralement fondés sur des forces inertielles. Dans cette étude, une modélisation fine des collecteurs électrostatiques a été conduite pour une géométrie fil / cylindre. Elle décrit tout d'abord les champs hydrodynamiques d'un écoulement charriant des inclusions dans lequel est imposée une décharge couronne. Une injection éventuelle de vapeur dans la chambre de collecte a nécessité ensuite la détermination des champs de température et concentration de la vapeur. Une analyse dimensionnelle inspectionnelle a montré que ces champs possèdent deux termes de couplage fort dont on a justifié l'omission dans cette étude ; les phénomènes physiques mis en jeu ont alors pu être classés selon une cascade d'influences non réciproques et la résolution numérique du modèle s'en est trouvée facilitée. Quatre configurations d'écoulement différentes, caractérisées par des recirculations d'origine électro hydrodynamiques, ont été identifiées et leurs impacts sur les rendements de collecte quantifiés. De plus, une procédure de dimensionnement des filtres électrostatiques fondée sur un nombre de Deutsch représentatif des rendements a été mise en place. Son exploitation a montré l'intérêt de la mise en parallèle de petits collecteurs pour filtrer des débits d'air importants. Cette étude s'est achevée par l'analyse des effets engendrés par l'injection de vapeur dans la chambre de collecte. Elle a jeté les bases d'une explication pour l'augmentation des rendements de collecte résultant de cette injection. / Detection of airborne biological agents has become a major challenge especially in hospitals and the protection against bioterrorism. In this context, the miniaturization of analytical devices allows to consider their direct use in the field. To obtain a representative and concentrated sample, air filtration remains a delicate point. Among the various principles used to collect airborne particles, the use of electrical forces seems to be promising to improve performance beyond these of devices that are based on inertial forces.In this study, a detailed model of electrostatic collectors was developed in the wire/cylinder geometry. It first describes the hydrodynamic flow fields carring inclusions in which a corona discharge is imposed. Afterwards, the possible injection of steam into the collection chamber required the determination of the temperature and vapor concentration fields. An inspectionnal dimensional analysis justified the omission of two strong coupling terms. Therefore, in this study, the involved physical phenomena could be classified according to a non-reciprocal influences cascade and the numerical model is become simpler. Four different flow patterns, characterized by their electrohydrodynamic secondary flows, were identified and their impact on the collection efficiencies was quantified. In addition a design procedure of electrostatic filters, based on a representative efficiency Deutsch number, has been developed. This procedure shows the interest of parallelizing small collectors to filter important airflows. This study was completed by the analysis of the effects of steam into the collection chamber. It provides the basis for an explanation of the collection efficiencies increase related to this injection.

L'objectif de cette étude était de préparer et de caractériser les particules submicroniques multifonctionnelles utilisables simultanément pour le diagnostic et le traitement de plusieurs maladies mortelles telles que le cancer. Pour ce faire, une étude systématique a été réalisée afin de comprendre les mécanismes impliqués et d'optimiser les paramètres du procédé de double émulsion-évaporation de solvant pour la préparation de ces particules. Pour l’imagerie in vitro, des nanoparticules polymériques fluorescentes (FluoSpheres®) ont été encapsulées dans une matrice polycaprolactone dégradable en utilisant le procédé de l’émulsion double-évaporation de solvant. Pour l’imagerie invivo, des nanoparticules d'or colloïdal ont été préparées et encapsulées via le même procédé et parfaitement caractérisées. Enfin, pour application theranostic, les nanoparticules d'or (comme agent de contraste) et un actif moléculaire (hydrophile Nefopam et hydrophobe benzoate de benzyle) ont été encapsulés simultanément dans des particules de polycaprolactone. Ces particules multifonctionnelles ont été caractérisées et évaluées in vitro comme model de pénétration cutané / The objective of this study was to prepare and characterize multifunctional submicron particles that can be used for diagnosis and therapy of several fatal diseases including cancer (i.e theranostic). For this purpose, a systematic study was performed in order to optimize the process parameters for preparation of polymeric particle that can be used as a platform for effective delivery of drugs and imaging labels. The imaging agent (FluoSpheres®) was encapsulated via double emulsion solvent evaporation technique to be used fluorescent contrast agent and their in vitro evaluation was performed. Then, gold nanoparticles were prepared by using NaBH4 reduction method, characterized and encapsulated by polycaprolactone polymer for in vitro applications. Finally, the gold nanoparticle were loaded into polycaprolactone particle along with a hydrophilic drug (Nefopam) and a hydrophobic drug (benzyl benzoate) simultaneously. The prepared particles were then characterized physicochemically and in vitro skin penetration study was performed