Global ETD Search

11	Peristaltické čerpadlo / Peristaltic pump Burda, Radim January 2019 (has links) Cílem této diplomové práce je navrhnout peristaltické čerpadlo pro hemodialýzu s ohledem na minimalizaci tlakových pulzací. Pomocí analytické analýzy je navržen nový koncept redukce tlakových pulzací, který využívá zrychlení k navýšení tlaku v prostoru mezi válečky. Fungování peristaltického čerpadla je simulováno pomocí programu Ansys Fluent pro získání lepší představy o proudění v čerpadle. Souběžně s návrhem nového konceptu bylo navrženo více tradiční čerpadlo, které bylo následně vyrobeno a experimentálně odzkoušeno. Data získaná z experimentu mohou být dále použita pro nový koncept.
12	Achalázie jícnu - etiologie, patofyziologie a léčba. / Esophageal achalasia - etiology, pathophysiology and treatment. Vacková, Zuzana January 2020 (has links) Background: Achalasia is a primary esophageal motility disorder that can be classified into three types (I-III) based on high-resolution manometry (HRM). Exact pathogenesis is unknown, but immune-mediated processes and genetic predisposition play a role, which is supported by finding of a genetic risk variant (rs28688207 insertion) in HLA-DQB1 gene that is strongly associated with achalasia. Per-oral endoscopic myotomy (POEM) has become a standard treatment for achalasia, but the long-term efficacy, safety and impact on esophageal physiology are not fully understood. The aims of our studies were to perform the first genotype-phenotype analysis investigating the frequency of rs28688207 accross three HRM types of achalasia, to evaluate the efficacy and safety of POEM and to assess the post-POEM esophageal motility patterns. Patients and methods: These were three retrospective studies of prospectively collected data. Genotyping of the rs2868827 insertion was performed using real-time PCR in 347 patients from Czech Republic (n = 163), Germany (n = 114), Greece (n = 70). The efficacy and safety of POEM were evaluated in 133 patients treated in our center. The post-POEM esophageal motility was assessed using the Chicago Classification in 237 patients in whom HRM was performed prior to and after POEM....
13	Development of New Treatment Modalities for Kidney/Ureter Stones Najafi, Zahra 10 September 2015 (has links) No description available. Biomedical Engineering Biomechanics Design Computational Fluid Dynamic ureter peristaltic mathematical model design of a new smart kidney basket
14	Computational Modeling of Biological Membrane and Interface Dynamics Lindahl, Erik January 2001 (has links) No description available. Molecular dynamics solvent diffusion phospholipid bilayers mesoscopic dynamics undulations peristaltic motions local virial lateral pressure profiles NMR relaxation reorientation dynamics diffusion bilayer aggregation
15	Computational Modeling of Biological Membrane and Interface Dynamics Lindahl, Erik January 2001 (has links) No description available. Molecular dynamics solvent diffusion phospholipid bilayers mesoscopic dynamics undulations peristaltic motions local virial lateral pressure profiles NMR relaxation reorientation dynamics diffusion bilayer aggregation
16	Modélisation du transport, de la dégradation et de l'absorption des aliments dans l'intestin grêle / Modelling of feedstuffs transport, degradation and absorption in the small intestine Taghipoor, Masoomeh 24 September 2012 (has links) L’objectif de cette étude est de modéliser la digestion dans l’intestin grêle : le transport des aliments par les ondes péristaltiques, la dégradation par les enzymes endogènes et exogènes et l’absorption active et passive. Un modèle mécaniste basé sur les équations différentielles ordinaires a été utilisé pour représenter la digestion. Les équations décrivent l’évolution de la position et de la composition du bolus provenant de l’estomac. Nous montrons ensuite par les méthodes d’homogénéisation mathématiques que ce modèle peut être considéré comme une version macroscopique des modèles plus réalistes, qui contiennent des phénomènes biologiques à des échelles inférieures de l’intestin grêle. Enfin, nous étudions l’influence du changement de la structure de bolus sur la digestion en intégrant les fibres alimentaires dans sa composition. Les deux principales caractéristiques des fibres alimentaires qui interagissent avec la fonction de l’intestin grêle, à savoir, la viscosité et la capacité de rétention d’eau ont été modélisées. / The purpose of this study is to model the digestion in the small intestine : transport of the the bolus by the peristaltic waves, feedstuffs degradation according to the endogenous and exogenous enzymes and nutrients absorption. A mechanistic model based on ordinary differential equations is used to represent the digestion. The equations describe the evolution of the position and composition of the bolus of feedstuffs coming from the stomach. We prove by using the homogenization methods, that this model can be considered as a macroscopic version of more realistic models which contain the biological phenomena at lower scales of the small intestine. Finally, we investigate the digestion of a non-homogeneous feedstuffs matrix by integrating the dietary fibre in the bolus. The two main physiochemical characteristics of dietary fibre which interact with the function of the small intestine, i.e. viscosity and water holding capacity are modelled. Modélisation EDO Digestion Intestin grêle Péristaltique Homogénéisation Solutions de viscosité Fibres alimentaires Modelling ODE Digestion Small intestin Peristaltic Homogenization Viscosity solutions Dietary fibres
17	Le Comportement de la bulle et des particules, l’écoulement pulsatile et le flux péristaltique / The Behavior of Bubble and Particle, Pulsatile and Peristaltic Flow Mingalev, Stanislav 13 December 2013 (has links) Dans cette thèse on cherche à étudier le flux péristaltique des liquides dans un canal à onde de pression déterminée aux confins. Dans la plupart des recherches de systèmes de transportation péristaltiques la variation des coordonnées de la paroi est prédéfinie pour les raisons de commodité. Cependant les parois d’organes creux (comme oesophage intestin grêle, côlon urètre, vaisseaux lymphatiques) dont le fonctionnement consiste à transmettre des produits par la voie péristaltique, sont dotées de barorécepteurs – capteurs qui perçoivent la pression dans la couche limite de fluides et servent à réguler le calibre des vaisseaux. Pour créer le modèle du comportement des systèmes biologiques pareils il nous semble plus adéquat de prédéfinir l’onde de pression aux confins des vaisseaux. Cette approche réalisée dans notre thèse permet de découvrir et décrire des effets nouveaux, inexplorés auparavant. Dans cette thèse nous étudions aussi l’influence des pulsations transversales des parois du canal sur la transmission du produit dues aux chutes de pression. Cet objectif est apparu lors de la détermination de la viscosité du liquide utilisant la méthode des canaux compressibles (squeezing flow viscometry). Des problèmes similaires sont assez répandus dans l’étude d’une variété des systèmes biologiques, en particulier, des mouvements de lubrification des articulations ou des micro-vaisseaux des muscles. Nous avons aussi étudié l’influence du son sur l’interaction d’une particule solide tombante et d’une bulle de gaz montante dans le liquide. La pertinence de ce travail est liée à l’importance de recherche des solutions possibles pour augmenter l’efficacité de flottation, méthode d’enrichissement basée sur l’accrochage des particules minérales par des bulles de gaz / The thesis studies the peristaltic flow of fluid in a channel with the specified pressure wave at the boundary. The law of wall’s coordinate variation isn’t determined a priori. It is found from the initially definite law of pressure-variation on the wall. This way is based on the fact that some hollow organs change diameter under the signals of baroreceptors (sensors that detects the pressure). We studied the effects of various parameters on flow rate and structure of flow. Besides we studied the influence of vibration on the peristaltic flow under long wave approximation. The paper also considers the influence of the wall transverse pulsation on the fluid transport under the pressure drop. This problem arises in defining the liquid viscosity by squeezing flow viscometry. The same problems occur in analyzing different biological systems, including the lubricant movement in joints or in the microvessels of working muscles. The influence of sound on the interaction of a solid particle and a gas bubble in fluid is studied as well. Écoulement de Poiseuille Écoulement pulsatile Péristaltisme Particules Bulles Interaction Poiseuille flow Pulsating walls Squeezing flow Peristaltic flow Particle Bubble Interaction 532.050 72 660.284 2
18	Vývoj cell-sorter systému s využitím optické pinzety a mikrofluidních čipů / Development of cell sorter system using optical tweezers and microfluid chips Novák, Pavel January 2011 (has links) In this master thesis I have been dealt with the design and construction of an instrumental platform that used positioning focused laser beam (so-called optical tweezers) for manipulation with living cells without their damage.
19	Design of a Bioreactor to Mimic Hemodynamic Shear Stresses on Endothelial Cells in Microfluidic Systems Lightstone, Noam S. 26 June 2014 (has links) The mechanisms behind cardiovascular disease (CVD) initiation and progression are not fully elucidated. It is hypothesized that blood flow patterns regulate endothelial cell (EC) function to affect the progression of CVDs. A system that subjects ECs to physiologically-relevant shear stress waveforms within microfluidic devices has not yet been demonstrated, despite the advantages associated with the use of these devices. In this work, a bioreactor was designed to fulfill this need. Waveforms from regions commonly affected by CVDs including were derived. Pump motion and fluid flow profiles were validated by actuator motion tracking, particle image velocimetry, and flowmeters. While several relevant waveforms were successfully replicated, physiological waveforms could not be produced at physiological frequencies owing to actuator velocity and accuracy limitations, as well as dampening effects in the system. Overall, this work lays the foundation for designing a system that provides insight into the role of shear stress in CVD pathogenesis. Endothelial cell Bioreactor Flow loop Cardiovascular disease CVD Waveform Microfluidics Microfluidic devices Hemodynamics EC Shear stress Shear Pump Actuator Mechanical engineering Biomedical engineering PIV Particle image velocimetry Fluid dynamics Fluid mechanics Pressure Model Syringe Peristaltic Blood Blood flow Wall shear stress Womersley number Womersley Purday Physiological Flowmeter Sinusoid Sinusoidal Disturbed Non-disturbed Undisturbed Oscillatory Pulsatile In vivo In vitro 0548 0541
20	Design of a Bioreactor to Mimic Hemodynamic Shear Stresses on Endothelial Cells in Microfluidic Systems Lightstone, Noam S. 26 June 2014 (has links) The mechanisms behind cardiovascular disease (CVD) initiation and progression are not fully elucidated. It is hypothesized that blood flow patterns regulate endothelial cell (EC) function to affect the progression of CVDs. A system that subjects ECs to physiologically-relevant shear stress waveforms within microfluidic devices has not yet been demonstrated, despite the advantages associated with the use of these devices. In this work, a bioreactor was designed to fulfill this need. Waveforms from regions commonly affected by CVDs including were derived. Pump motion and fluid flow profiles were validated by actuator motion tracking, particle image velocimetry, and flowmeters. While several relevant waveforms were successfully replicated, physiological waveforms could not be produced at physiological frequencies owing to actuator velocity and accuracy limitations, as well as dampening effects in the system. Overall, this work lays the foundation for designing a system that provides insight into the role of shear stress in CVD pathogenesis. Endothelial cell Bioreactor Flow loop Cardiovascular disease CVD Waveform Microfluidics Microfluidic devices Hemodynamics EC Shear stress Shear Pump Actuator Mechanical engineering Biomedical engineering PIV Particle image velocimetry Fluid dynamics Fluid mechanics Pressure Model Syringe Peristaltic Blood Blood flow Wall shear stress Womersley number Womersley Purday Physiological Flowmeter Sinusoid Sinusoidal Disturbed Non-disturbed Undisturbed Oscillatory Pulsatile In vivo In vitro 0548 0541

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