• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 550
  • 267
  • 256
  • 89
  • 77
  • 30
  • 26
  • 20
  • 12
  • 11
  • 11
  • 11
  • 11
  • 11
  • 11
  • Tagged with
  • 1560
  • 188
  • 188
  • 171
  • 115
  • 100
  • 97
  • 95
  • 85
  • 74
  • 74
  • 70
  • 66
  • 65
  • 65
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
491

Avaliação de programas de treinamento em manejo racional de bovinos em frigoríficos para melhoria do bem-estar animal /

Barbalho, Patrícia Cruz. January 2007 (has links)
Orientador: Mateus José Rodrigues Paranhos da Costa / Banca: Isabella Dias Barbosa Silveira / Banca: Ricardo Andrade Reis / Resumo: Os objetivos foram estudar os efeitos de um programa de treinamento em manejo racional no bem-estar de bovinos e testar a viabilidade prática da aplicação do manejo racional em frigoríficos. Os comportamentos de humanos e bovinos foram estudados em três frigoríficos durante o desenvolvimento de dois processos: 1) condução dos bovinos dos currais de espera até o boxe de atordoamento e 2) atordoamento. Nas avaliações do processo de condução dos animais foram acompanhados 31, 22 e 18 lotes de animais antes do treinamento nos frigoríficos MT, GO e SP, respectivamente, repetindo-se o mesmo número de lotes após o treinamento. Foram registradas duas variáveis do comportamento humano durante a condução dos animais (uso do bastão elétrico e uso inadequado da bandeira) e três do comportamento bovino (escorregões, quedas e vocalizações). Durante o processo de atordoamento foram consideradas duas variáveis, a eficiência de atordoamento (sendo observados 336, 475 e 314 animais nos frigoríficos MS, GO e SP, respectivamente, em cada etapa, antes e após o treinamento) e sinais de insensibilidade (com 400, 453 e 308 animais nos frigoríficos MS, GO e SP, respectivamente, em cada etapa). Os dados sobre a condução dos bovinos foram analisados usando-se Anova com o procedimento GLM e para as variáveis de atordoamento foi utilizado o Teste de Kruskall-Wallis. Houve diferenças significativas (P<0,01) entre frigoríficos nas variáveis escorregões, quedas, uso do bastão elétrico e sinais de insensibilidade. Também houve efeito significativo do treinamento para a maioria das variáveis estudadas, sendo que o maior efeito foi no uso do bastão elétrico, que diminuiu nos três frigoríficos após o treinamento. Os resultados indicaram que os frigoríficos que realizaram investimentos em mão de obra e instalações, atingiram melhor resposta ao treinamento dos funcionários. / Abstract: The objectives of this research were to study the effects of rational handling training programs on cattle welfare and to test the practical feasibility of the rational handling in the slaughterhouse. The human and cattle behaviours were recorded in three slaughterhouses during two processes: 1) leading cattle from lairage to stunning boxes and 2) stunning cattle. In order to assess the handling procedures during the first process we studied 31, 22 and 18 groups of cattle, before and after the training activity, in three slaughterhouses (MT, GO and SP); in this process five variables were considered, two of them related to human behaviour (the frequency of electric prod and the frequency of inadequate flag use) and three related to cattle behaviour (the frequencies of slips, falls and vocalizations). For the assessment of the stunning process two variables were defined: stunning efficiency (with 336, 475 and 314 cattle observed before and after the training period) and insensitiveness (with 400, 453, and 308 animals observed before and after training). Analysis of variance was used for data related to the process of driving the animals to the stunning box and the Kruskall- Wallis test was used when for the variables related to the stunning process. Significant statistical differences were found among slaughterhouses for the frequencies of slips, falls, use of the electric prod and insensitiveness. Similar results were found when considered the effects of training, being the major effect on the frequency of electric prod use, which dropped down in three slaughterhouses. Inadequate facilities and equipments promoted depreciation on the labour, increasing the frequencies of slips, falls and in the number of sensitive animals after stunning. The results suggested that the slaughterhouses that did invest in people, training, facilities and equipments achieved a better result in the improvement of animal welfare. / Mestre
492

Skladování v logistickém systému podniku Foxconn CZ / Storage inside the Logistics System in Company Foxconn CZ

Lízálková, Jana January 2009 (has links)
The aim of the Diploma work is to design the storage system inside the logistics system of the company Foxconn CZ. To achieve this goal it is necessary to theoretically define the main terms concerning integrated logistics chain, describe the function and localization of warehouses, describe the most often used warehouse equipment, handling equipment and logistics technologies. Closer acquaintance with company Foxconn CZ allowed us to understand its strategy. Based on collected and analyzed inputs concerning production and warehouses in newly built building the appropriate ways of storing reflecting the specific requirements of individual storage locations was designed. Based on evaluation of aspects of the proposed options the most appropriate way of storing was recommended.
493

AnÃlise da efetividade de manejo de Ãreas marinhas protegidas: um estudo do Parque Estadual Marinho da Pedra da Risca do Meio / Analyse of the effectiveness of degree of marine protected areas: a study of the Pedra da Risca do Meio Marine State Park

Joseilton Ferreira Lima Filho 18 July 2006 (has links)
InstituÃdas como uma reaÃÃo limitante ao crescimento desmedido do homem sobre o ambiente natural, as Ãreas protegidas apresentam-se presentemente como um relevante componente nas estratÃgias de conservaÃÃo ambiental mundial. MÃltiplos tipos de ecossistemas ameaÃados pela utilizaÃÃo predatÃria de suas extensÃes beneficiam-se diretamente da instituiÃÃo de regras de condutas impostas pela criaÃÃo de unidades de conservaÃÃo, dentre estes, encontram-se as Ãreas marÃtimas. No entanto, assim como espaÃos terrestres, a mera implantaÃÃo de uma Ãrea marinha protegida nÃo garante a preservaÃÃo do ambiente indicado. Deve-se primar pelo exercÃcio de atividades administrativas eficientes que permitam que os objetivos de conservaÃÃo do espaÃo sejam atingidos, de forma a beneficiar o maior nÃmero possÃvel de setores da sociedade local. Visando analisar o grau de efetividade do manejo do Parque Estadual Marinho da Pedra da Risca do Meio, Ãnica unidade de conservaÃÃo marinha do Estado do CearÃ, construiu-se um instrumental metodolÃgico baseado na anÃlise de 24 variÃveis, distribuÃdas entre 7 Ãmbitos. Para cada Ãmbito, foram elaboradas matrizes de avaliaÃÃo que permitiram a classificaÃÃo da efetividade do manejo de cada um destes e, ao integrÃ-los, da unidade de conservaÃÃo em si. A contribuiÃÃo inovadora deste estudo foi o desenvolvimento de uma metodologia que, embora apresente pontos em comum com metodologias anteriormente utilizadas, seja aplicada Ãs Ãreas marinhas protegidas, unidades de conservaÃÃo ainda carentes de estudos sobre eficiÃncia de manejo. Desta forma, a anÃlise do manejo do Parque Estadual Marinho da Pedra da Risca do Meio resultou em 61,46% do seu nÃvel Ãtimo, classificando-o como possuidor de um manejo medianamente satisfatÃrio. Inferiu-se, portanto, que apesar de possuir requisitos bÃsicos de manejo de uma unidade de conservaÃÃo essa Ãrea ainda apresenta lacunas estruturais e administrativas que dificultam o estabelecimento de aÃÃes eficazes na conservaÃÃo dos recursos naturais locais. / Created as a reaction to unlimited growth of modern society over environment, protected areas are nowadays distinctive components in a world-wide conservation strategy. Many kinds of threatened ecosystems are directly benefited by them, avoiding predatory uses of its extensions due to restrictions of behaviors imposed by their establishment. Amongst these, there are maritime areas. However, as well as terrestrial spaces, the mere creation of a marine protected area does not guarantee the environment preservation. The development of efficient administrative activities is really necessary, allowing the reach of its conservation objectives, whilst benefiting the largest possible number of society sectors. Aiming to analyze the effectiveness degree of Pedra da Risca do Meio Marine State Park handling, the only marine protected area of CearÃ, it was established a methodology that analysis 24 variables distributed between 7 ambits. For each ambit, it was elaborated an evaluation matrix that allows a qualification of its handling effectiveness. Integrating all evaluated sector, it was possible to measure the marine protected areaâs handling effectiveness. The analysis of Pedra da Risca do Meio Marine State Park handling effectiveness resulted in a 61.46% of its excellent level, being classified as a medium satisfactory handling. It was inferred, therefore, that although it possess the basic requirement of handling, this marine protected area still have structural and administrative gaps that make it difficult to establish efficient actions in local natural resources conservation.
494

Uma abordagem transacional para o tratamento de exceções em processos de negócio. / A transactional approach to exception handling in business process.

Pedro Paulo de Souza Bento da Silva 12 June 2013 (has links)
Com o intuito de tornarem-se mais eficientes, muitas organizações -- empresas, órgãos governamentais, centros de pesquisa, etc. -- optam pela utilização de ferramentas de software para apoiar a realização de seus processos. Uma opção que vem se tornando cada vez mais popular é a utilização de sistemas de Gestão de Processos de Negócio (GPN), que são ferramentas genéricas, ou seja, não são específicas a nenhuma organização, altamente configuráveis e ajustáveis às necessidades dos objetos de atuação de cada organização. Uma das principais responsabilidades de um sistema de GPN é prover mecanismos de tratamento de exceções à execução de instâncias de processos de negócio. Exceções, se forem ignoradas ou se não forem corretamente tratadas, podem causar o aborto da execução de instâncias e, dependendo da gravidade da situação, podem causar falhas em sistemas de GPN ou até mesmo em sistemas subjacentes (sistema operacional, sistema gerenciador de banco de dados, etc.). Sendo assim, mecanismos de tratamento de exceções têm por objetivo resolver a situação excepcional ou conter seus efeitos colaterais garantindo, ao menos, uma degradação controlada (graceful degradation) do sistema. Neste trabalho, estudamos algumas das principais deficiências de modelos atuais de tratamento de exceções, no contexto de sistemas de GPN, e apresentamos soluções baseadas em Modelos Transacionais Avançados para contorná-las. Isso é feito por meio do aprimoramento dos mecanismos de tratamento de exceções da abordagem de modelagem e gerenciamento de execução de processos de negócio WED-flow. Por fim, estendemos a ferramenta WED-tool, uma implementação da abordagem WED-flow, através do desenvolvimento de seu gerenciador de recuperação de falhas. / With the aim of becoming more efficient, many organizations -- companies, governmental entities, research centers, etc -- choose to use software tools for supporting the accomplishment of its processes. An option that becomes more popular is the usage of Business Process Management Systems (BPM), which are generic tools, that is, not specific to any organization and highly configurable to the domain needs of any organization. One of the main responsibilities of BPM Systems is to provide exception handling mechanisms for the execution of business process instances. Exceptions, if ignored or incorrectly handled, may induce the abortion of instance executions and, depending on the gravity of the situation, induce failures on BPM Systems or even on subjacent systems (operational system, database management systems, etc.). Thus, exception handling mechanisms aim to solve the exceptional situation or stopping its collateral effects by ensuring, at least, a graceful degradation to the system. In this work, we study some of the main deficiencies of present exception handling models -- in the context of BPM Systems -- and present solutions based on Advanced Transaction Models to bypass them. We do this through the improvement of exception handling mechanisms from WED-flow, a business process modelling and instance execution managing approach. Lastly, we extend the WED-tool, an implementation of WED-flow approach, through the development of its failure recovery manager.
495

Aplicação de métodos numéricos de otimização ao problema conjunto da dirigibilidade e conforto veicular. / Numerical optimization methods applied to the combined ride and handling problem.

Vilela, Daniel 15 March 2010 (has links)
O trabalho desenvolvido tem como objetivo aplicar metodologias de otimização de suspensão para veículos de passageiro e comerciais leves, baseando-se em parâmetros de dirigibilidade e conforto veicular, através do uso de simulação numérica computacional. São apresentadas métricas objetivas utilizadas para a avaliação de um veículo com relação ao seu desempenho em termos de dirigibilidade e conforto e é proposta uma nova métrica global conjunta. São desenvolvidos no trabalho modelos analíticos para quantificar as métricas de dirigibilidade. Os resultados obtidos foram comparados com medições experimentais e resultados de modelos multicorpos mais complexos, atingindo o nível de correlação necessário para os propósitos deste trabalho. Alguns dos modelos analíticos desenvolvidos são contribuições inovadoras deste trabalho, não tendo correspondente anterior na literatura. É apresentada a modelagem dinâmica vertical que possibilita avaliar as métricas de conforto, cuja aplicação foi feita em conjunto com os modelos analíticos de dirigibilidade desenvolvidos, obtendo-se uma avaliação global conjunta. Três ferramentas de otimização são apresentadas e avaliadas na aplicação ao problema de otimização global. A análise comparativa dos resultados dos métodos de otimização permite identificar qual método mais adequado com relação ao desempenho computacional, praticidade de uso e disponibilidade de informação. Finalmente, demonstra-se que a aplicação da otimização numérica proporciona resultados efetivos para melhoria do produto, trazendo ganhos de tempo e custo no desenvolvimento de um novo projeto. / This work is intended to apply suspension set-up optimization methodologies to passenger vehicles and pick-up trucks based on their ride and handling parameters through the use of numerical computational simulation. Metrics used to evaluate a vehicle regarding its performance in terms of ride and handling are shown and a new global single metric for ride and handling is proposed. Analytical models are developed to quantify the vehicle handling metrics. The results obtained were compared with experimental measurements and the results of more complex multibody models, achieving the correlation level required for the purposes of this work. Some of the analytical models herein developed are new contributions from this work and were not previously available in the literature. The vertical dynamic model that allows the computation of the ride comfort metrics is shown, and its application simultaneously with the analytical handling models developed allows the calculation of the proposed global single ride and handling metric. Three different optimization techniques are presented and studied in order to compare their performance for the proposed problem. The comparative analysis among the optimization results allows determining where each method is more adequate with respect to computational performance, usage friendliness and information availability. Finally, it is shown that the application of numerical optimization is effective to improve the product performance, with gains in terms of development time and cost for a new project.
496

Design of regional pillars for the Khuseleka Ore Replacement Project (KORP) - UG2

Mutsvanga, Clarence January 2017 (has links)
A research report submitted to the Faculty of Engineering and Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering, Johannesburg 2017 / Depletion of mineral resources is a reality of mining. It is critical that as resources get depleted, new reserves are subsequently opened up continuously if a mine is to continue operating. Failure to open up new reserves will result in a mining operation running out of reserves and ultimately ceasing operations. Besides the economic considerations of an ore reserve such as the grade and tonnage, stability of the mining operation is of equal importance. A mine should remain stable for the entire period that it remains operational. Pillars play a critical role in ensuring the stability of an excavation; actually, regional pillars ensure the overall stability of a mine. It therefore goes without saying, pillar design is an integral component of any successful mine design. This project was undertaken with the objective of ensuring that the new reserves being opened up in the Khuseleka Ore Replacement Project (KORP) section are not only profitable, but also stable. This was done through a) maximisation of extraction ratio, thereby maximising the mines’ profitability. b) designing the regional pillar layout for the KORP section using current empirical and numerical pillar design methods and comparing the results to come up with the most optimal design. c) ensuring the stability of the on and off reef mine infrastructure by determining the Rockwall Condition Factor (RCF) values on the footwall infrastructure due to pillars left above and thus prevent damage to these excavations through stress induced failures. Consideration was given to the standard Khuseleka footwall infrastructure layouts for the design based on the planning department’s layout of haulages and crosscuts for the KORP section. The layout of the footwall excavations indicated that the pillars would be differently sized thereby having an influence on the APS, pillar strength and factors of safety of the regional pillars. d) numerical modelling analysis of the effects of leaving stabilizing pillars on the 27 raise line where the haulages intersect the reef horizon. The methodology employed for this undertaking involved a critical literature review of existing pillar design methods, applying and comparing them, and coming up with an economic and safe design. To be able to design a pillar layout that met the objectives listed above, engineering design principles had to be applied. It involved gathering the relevant geological and geotechnical information required as input parameters for the different empirical and numerical analyses methods. What came out from this project was that each method employed yielded its own set of results. This highlighted the need to understand the context under which a design is carried out and the shortcomings of each method employed. It showed how important it is to have all the relevant information of not only the characteristics of the rock mass in which an excavation will be made, but also on the strengths and limitations of the tools available to design a structure. It highlighted the fact that to minimize uncertainty and have a more robust design, it was necessary to spend time and effort in gathering as much relevant data as possible. In the end engineering judgment was used to decide on the best method or system to employ in the design of the pillars. / XL2018
497

O manejo do Diabetes Mellitus tipo 1 na perspectiva de crianças / Type 1 Diabetes Mellitus management from children\'s perspective

Sparapani, Valéria de Cássia 31 March 2010 (has links)
O adequado manejo do DM Tipo 1 tem se tornado um desafio, principalmente para as próprias crianças, em virtude da presença de comportamentos, habilidades e conhecimentos inadequados que colaboram para a não adesão ao tratamento e para aumento de complicações em longo prazo. Estudos têm demonstrado que compreender as experiências de vida das crianças nos seus diversos espaços, valorizando-as e buscando maior aproximação com as mesmas, pode contribuir para a partilha do conhecimento sobre o manejo do diabetes e para o maior envolvimento da criança no cuidado. O objetivo deste trabalho foi compreender, na perspectiva de crianças com DM Tipo 1, os fatores que interferem no manejo da doença. Trata-se de uma pesquisa qualitativa, de natureza exploratória. Participaram do estudo 19 crianças. Utilizamos a entrevista semiestruturada e, como recurso facilitador da comunicação com a criança, os fantoches. Esses brinquedos foram confeccionados pelas próprias crianças e criou-se, também, um cenário que ilustrou e complementou a utilização dos fantoches no dia da entrevista. A análise dos dados empíricos foi feita por meio da análise de conteúdo. Os resultados evidenciaram a compreensão do que é ser criança com diabetes e dos fatores relacionados à sua existência, como seus sentimentos e percepções. A compreensão da interação da criança com os conhecimentos que possui sobre a sua doença, sua inserção no processo do autocuidado, as habilidades desenvolvidas e os recursos disponíveis para lidar com as demandas da doença constituem fatores que interferem de forma positiva ou negativa no manejo da doença e merecem ser foco de atenção dos profissionais de saúde. Todos esses elementos atuam dinamicamente nos espaços do cotidiano da criança, tais como o familiar, o escolar, o de amizades, o de lazer e o dos serviços de saúde, atuando como fatores que fragilizam ou potencializam o manejo da doença. O apoio de familiares, amigos, professores e profissionais de saúde que compartilham as experiências de ser uma criança com diabetes mostrou-se essencial para o alcance do adequado manejo. Além disso, o conhecimento adquirido por estes atores e pela própria criança interfere diretamente no manejo do DM Tipo 1. Os resultados deste estudo evidenciam ações que visam a fortalecer o trabalho da equipe multidisciplinar no cuidado da criança com diabetes e apontam cenários de atuação que podem ser incrementados pelos profissionais de saúde. O enfermeiro ocupa posição privilegiada para identificar e operacionalizar ações apropriadas ao estágio de desenvolvimento da criança e às suas necessidades, em todos os espaços em que vive, atuando, assim, em consonância com todos os envolvidos em prol do sucesso do manejo da doença. / The adequate handling of Type 1 DM has become a challenge, mainly for the children themselves, due to the presence of inadequate behaviors, skills and knowledge that contribute to non-adherence to treatment and increased complications in the long term. Research has demonstrated that understanding children\'s life experiences in their different spaces, valuing them and seeking greater approximation, can contribute to knowledge sharing on diabetes management and to the children\'s greater involvement in care. This research aimed to understand, from the perspective of children with Type 1 DM, the factors that interfere in the management of this disease. This is a qualitative and exploratory research. Study participants were 19 children. Semi-structured interviews were used and, to facilitate communication with the child, puppets, which the children made themselves. A scenario was also created to illustrate and complement the use of puppets on the day of the interview. Content analysis was used for empirical data analysis. Results evidenced the understanding of what it means to be a child with diabetes and the factors related to his/her existence, such as feelings and perceptions. Understanding of these children\'s interaction with their knowledge about their disease, their insertion in the self-care process, developed skills and resources available to deal with the demands of the disease constitute factors that interfere positively or negatively in disease management and deserve further attention from health professionals. All of these elements act dynamically in the child\'s daily spaces, such as the family, school, friendships, leisure and health services, as factors that weaken or strengthen disease management. Support from relatives, friends, teachers and health professionals who share the experiences of being a child with diabetes showed to be essential to achieve adequate management. Moreover, the knowledge these actors and the children themselves acquire interferes directly in Type 1 DM management. These study results evidence actions aimed at strengthening the work of the multidisciplinary team in care delivery to children with diabetes and indicate activity scenarios which health professionals can build upon. Nurses play a privileged role to identify and put in practice actions that are appropriate for the children\'s development stage and needs, in all spaces they live in. Thus, they act in line with all parties involved with a view to successful disease management.
498

Improving the Nursing Practice Environment With Point of Care Specimen Collection

Saathoff, April Marie 01 January 2017 (has links)
Specimen collection and identification errors are a significant problem in healthcare, contributing to incorrect diagnoses, delayed care, lack of essential treatments, patient injury or death, increased length of stay and increased healthcare costs, and decreased patient satisfaction. The purpose of the project was to evaluate the implementation of specimen collection technology with barcode scanning and bedside label printing in the maternal child health division of a community teaching hospital. The project was driven from Donabedian's quality framework for healthcare implementations, indicating that evaluating the quality of health care can be drawn from the categories of structure, process, and outcomes. The project featured a quantitative analysis with a pretest-posttest design. Mislabeled specimen rates and collection turnaround times were generated from laboratory quality data and measured before, during, and after implementation of specimen collection technology. Data analysis using an independent samples t test in SPSS 17.0 compared the changes in the mean scores of specimen collection turnaround times and mislabeled specimen rates. Mislabeled specimen percentages in all areas decreased from 0.0250% preimplementation to 0.0023% postimplementation with a p value less than 0.001. Collection turnaround times greater than 60 minutes decreased following implementation of specimen collection technology by 22% with a p value less than 0.001. The implementation of specimen collection technology has positive implications for social change, including the expectation that as technology is proven to significantly improve the safety and quality of laboratory collections, there will be a mandate for implementation of safer collection processes in healthcare.
499

Studies on the Comparative Value of the Hot Treatment (Krantz Patent) and Common Methods of Handling Barnyard Manure

Winkler, Orval E. 01 May 1934 (has links)
Antidating written human history the dung of animals, chalk, marl, wood ashes and other substances were probably used to increase the productivity of the soil. These practises found their way into the earliest farming activities of the Chinese, Persians, Greeks and Romans. (3)(11) In the Hebrew scriptures mention is made of the "Dung Gate". (10) This was undoubtedly a place given to the marketing of manures. That manure was used as a soil amendment in Asia Minor in Biblical times is not questioned. The famous Roman agricultural writer Cato (234 B.C.) wrote at length on manures and their handling. He gave bird manure preference and spoke of the manurial value of legumes. (3) Jethro Tull believed tillage was manure and contended that manures only benefit the soil because of improved physical condition after application. Liebig, the well known German agricultural chemist, gave prominence to the theory that small quantities of minerals added to the soil would suffice as manure. (1) Today the general ideas of soil fertility and the use of manures and fertilizers incorporates the views of these earlier students with better explanations of the relationships of one usage to the other. (19)(26)(29)(30) The study here reported is limited to other methods of handling barnyard manure and particularly to the recent development in Germany of what is known as "Hot Processing."
500

Electrocinétique tridimensionnelle de particules colloïdales en géométrie microfluidique et application à la manipulation de cellules / 3D electrokinetics of colloidal particles in microfluidic channels and application to cell handling

Honegger, Thibault 17 November 2011 (has links)
Les propriétés électrocinétiques de cellules ou de complexes colloïde-cellule visant leur manipulation individuelle dans une puce microfluidique devrait permettre de proposer de nouveaux types d'application dans le domaine des laboratoires-sur-puce et de la recherche biomédicale. Les travaux présentés dans ce manuscrit visent à créer une nouvelle technologie de puce microfluidique permettant la manipulation électrocinétique tridimensionnelle sans contact de particules colloïdales. Cette technologie innovante associée à la réalisation de particules colloïdales multifonctionnelles (Janus) permet d'étudier et de contrôler les interactions d'un complexe colloïde-cellule. Une technologie originale de puce microfluidique tridimensionnelle transparente présentant des niveaux d'électrodes biplanaires est développée sans couche résiduelle classiquement présente dans les technologies de scellement microfluidique. Parallèlement, de nouveaux types de colloïdes anisotropes (Janus) et multifonctionnels (fluorescents, fonctionnalisés avec des protéines…) sont fabriqués en associant la synthèse colloïdale aux techniques de la microélectronique et à la fonctionnalisation de surface. La compréhension et l'exploitation des forces électrocinétiques créées par un champ électrique alternatif et non-uniforme sur la solution colloïdale confinée dans cette puce permettent de proposer une nouvelle méthode de détermination du facteur de Clausius-Mossotti. Ce facteur est un paramètre intrinsèque à la solution colloïdale qui régit la force diélectrophorétique. La détermination expérimentale de ce facteur, combinée à une analyse théorique pour les solutions colloïdales étudiées, définit les paramètres du champ électrique à appliquer (fréquence, tension) pour localiser, séparer ou manipuler en trois dimensions des particules micrométriques de tout type (particules nu, fonctionnalisées, disymétriques…). Le mélange de ces particules dans des milieux de culture cellulaire contenant des cellules de lignées humaines crée des complexes colloïde-cellule. En fonction du type cellulaire, ces complexes se caractérisent par une cellule ayant internalisé des colloïdes ou une cellule décoré par des colloïdes attachés sur sa membrane. Soumis à des forces électrocinétiques déterminées, ces complexes démontrent des réponses duales des particules et des cellules contrôlables indépendamment. En combinant l'ingénierie des particules colloïdales et la technologie microfluidique de manipulation électrocinétique sans contact, des forces locales peuvent être exercées sur les cellules par l'intermédiaire des particules. / The electrokinetics properties of cells or a particles-cell complex for their individual handling in a microfluidic chip open the way to new applications for lab-on-chip or biomedical research fields. The work presented in this thesis aims to create a new technology of microfluidic chips able to perform 3D electrokinetic contactless handling of colloidal particles. Combined with the microfabrication of multifunctional (Janus) colloidal particles this technological breakthrough allows the study and the control of colloidal particles and cells. An innovative technology of a 3D transparent microfluidic chip that integrates two levels of bi-planar electrodes is developed without any residual layer commonly stacked in microfluidic sealing technology. At the same time, a new type of anisotropic particles (Janus) and multifunctional (fluorescence, functionalized with proteins) are microfabricated by combining colloidal synthesis, microelectronics process and surface functionalization techniques. The understanding and the use of electrokinetic forces that are created by a non-uniform electric field in a colloidal solution confined in this chip enable the access to a new method of determination of the Claussius-Mossotti factor. It is an intrinsic parameter of a colloidal solution that rules the dielectrophoretic force. Its experimental determination, combined with a theoretical analysis of the colloidal solution, defines the parameters of the electric field to apply (frequency, applied voltage) in order to localize, separate or handle in 3D all types of micrometer sized particles (plain, functionalized, dissymmetric). The mixing of particles in cell culture mediums that contain human lines cells creates a particle-cell complex. According to the cellular type, those complexes are characterized by a cell that has internalized particles or is decorated by particles attached on its membrane. Submitted to determined electrokinetic forces, those complexes show dual responses that are controllable on both particles or cell independently. By associating the engineering of colloidal particles and this electrokinetic contactless handling microfluidic technology, local forces can be exerted on cells via those particles.

Page generated in 0.5851 seconds