• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 19
  • 5
  • 3
  • 2
  • 2
  • 2
  • 1
  • Tagged with
  • 40
  • 40
  • 7
  • 7
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • 4
  • 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.
31

The Study of Hereditary Spastic Paraplegia-Causing Gene DDHD2 Using Cell Models

Mongeon, Kevin 13 April 2018 (has links)
Hereditary spastic paraplegia type 54 is a rare autosomal recessive neurological gait disorder characterized by paraplegia, muscle spasticity, and intellectual disability. This length-dependent distal axonopathy is caused by mutations in the DDHD2 gene, which encodes the intracellular phospholipase A1 DDHD2. Little is known about the molecular function of the DDHD2 protein, especially in the context of HSP54. Thus, there is a need to further investigate its molecular functions and investigate the impact of DDHD2 deficiency in disease-relevant cells. Here, lipidomic profiling of dermal fibroblasts derived from three unrelated patients has revealed 19 glycerophosphoethanolamine species at differential levels in patients relative to unaffected controls. However, patient cells appear to have an unaffected Golgi apparatus morphology and lipid droplet formation, despite DDHD2’s proposed roles in these processes. To study the gene function in neuronal cells, I transdifferentiated the fibroblasts into induced neuronal precursor cells and found all the patient cells arrested in the G0/G1 phase of upon conversion. Given that these cell lines are unsustainable, I generated a stable knockdown cell line in the highly proliferative HEK293A to study the molecular biology of DDHD2. The knockdown cells had a reduced growth, were delayed in the G2/M phase of the cell cycle, and became multinucleated. I then treated the cells with antineoplastic compounds paclitaxel and nocodazole and found more knockdown cells in G0/G1 than controls, suggesting the possible occurrence of mitotic slippage. Lastly, I report a novel subcellular localization for DDHD2 at the microtubule organization center.
32

Příprava a charakterizace buněčných modelů lysosomálních dědičných onemocnění - mukopolysacharidos / Preparation and characterization of cell models of lysosomal hereditary diseases - Mucopolysaccharidoses

Presová, Gabriela January 2020 (has links)
Mucopolysaccharidoses are a group of diseases that belong to lysosomal storage disorders. A common sign of these monogenic multisystem diseases is a gene mutation leading to a deficiency of the lysosomal enzyme participating in glycosaminoglycan degradation. It results to their accumulation in the tissues and organs, where they cause a progressive damage. There is no efficient treatment available for most mucopolysaccharidoses. Moreover, the research is complicated because of the low prevalence and type of affected tissues. Animal models of these human diseases are used for an evaluation of newly developed therapeutic approaches. However, they also have many limitations due to the different pathogenesis and catabolic pathways of the accumulated substrates between humans and animals. Therefore, animal models are replaced by human cell models. In this thesis, the development of four mucopolysaccharidoses human cell models is reported (MPS IIID, MPS IVA, MPS IVB, MPS VI). Corresponding genes (GNS, GALNS, GLB1, ARSB) were inactivated using CRISPR/Cas9 technology, where plasmids containing specific inserts are delivered to the target human induced pluripotent stem cells (iPSC), using electroporation. Isolated clones, which represent iPSC disease models, were characterized by Sanger sequencing, enzyme...
33

Caractérisation de nouvelles lignées cellulaires pré-chimiothérapie et post-chimiothérapie du cancer épithélial de l'ovaire

Wang, Lu-Lin 04 1900 (has links)
Le cancer épithélial de l’ovaire (CÉO) est le cancer gynécologique le plus létal. Le CÉO de type séreux, la forme la plus commune avec plus de 50% des cas, est souvent diagnostiqué tardivement et associé à un mauvais pronostic. Le CÉO avancé, surtout traité par chimiothérapie, va devenir chimiorésistant chez la majorité des patientes traitées. Bien que des lignées cellulaires du CÉO aient été dérivées à partir de tumeurs solides et d’ascites de patientes ayant ou non subi une chimiothérapie, aucune des lignées cellulaires du CÉO provenant d’une même patiente avant et après ses traitements de chimiothérapie n’ont été établies précédemment. Notre laboratoire est le premier à développer de telles lignées cellulaires. Nos nouvelles lignées cellulaires sont dérivées de trois patientes différentes (1369, 2295 et 3133) et classées selon leur provenance, soit la tumeur solide (TOV) ou l’ascite (OV). Nous avons donc caractérisé ces nouvelles lignées de cellules pré-chimiothérapie (TOV1369TR, OV2295, TOV3133D et TOV3133G) et post-chimiothérapie (OV1369(2), OV2295(2), TOV2295, OV3133 et OV3133(2)) par diverses approches. Par immunohistochimie et immunobuvardage de type Western, nous avons caractérisé les niveaux d’expression de marqueurs épithéliaux typiques de kératines (KRT7, KRT8, KRT18, KRT19, KRT20) pour confirmer l’origine épithéliale et ovarienne des cellules. Nous avons également analysé le niveau d’expression de HER2 et p53, deux marqueurs importants dans le CÉO. Cependant, il ne semble pas y avoir d’expression différentielle évidente de ces marqueurs entre les lignées pré-chimiothérapie et post-chimiothérapie. Plus encore, nous avons étudié plusieurs caractéristiques tumorigéniques des lignées cellulaires, dont la prolifération cellulaire (par compte cellulaire), la migration cellulaire (par recouvrement de plaie), la capacité à former des sphéroïdes en 3D (par la méthode des gouttelettes inversées), et la formation de tumeurs in vivo dans des souris SCID (xénogreffes sous-cutanées). En général, il ne semble pas y avoir de différences claires entre les cellules pré-chimiothérapie et post-chimiothérapie au niveau du comportement cellulaire, à l’exception du fait qu’aucune des lignées post-chimiothérapie semblent être en mesure de former des structures tridimensionnelles compactes, contrairement à certaines lignées post-chimiothérapie. Nos résultats pourront servir à mieux comprendre les différents mécanismes régissant les tumeurs malignes du CÉO de type séreux et à mieux comprendre la progression de la maladie à travers les différents traitements, ce qui nous permettra d’acquérir des informations essentielles pour mieux évaluer et traiter différentes patientes. / Epithelial ovarian cancer (EOC) is the deadliest of all gynecologic cancers. The serous type of EOC is the most common form of the disease, and it accounts for more than 50% of the cases. It is often diagnosed at advanced stages where its prognosis is poor. Advanced EOC is treated mainly with chemotherapy. However, chemoresistance development eventually impedes the success of the treatments for most patients. Researchers have derived cell lines from EOC from solid tumors or from ascites. So far, there has not been EOC cell lines established from samples taken before and after chemotherapy treatments within the same patient. Our laboratory is thus the first to develop a new and powerful model of pre-chemotherapy and post-chemotherapy cell lines. All cell lines were derived sequentially from 3 different patients (1369, 2295 and 3133), from either solid tumors (TOV) or ascites (OV). We therefore characterized these new pre-chemotherapy cell lines (TOV1369TR, OV2295, TOV3133D and TOV3133G) and post-chemotherapy cell lines (OV1369(2), OV2295(2), TOV2295, OV3133 and OV3133(2)) through several approaches. Using immunohistochemistry and Western blot, we have characterized the level of expression of typical epithelial keratin markers (KRT7, KRT8, KRT18, KRT19, KRT20) to confirm the epithelial and ovarian nature of the cells. We have also analysed the expression level of important EOC markers, such as that of HER2 and p53, and found no clear difference between the pre-chemotherapy and post-chemotherapy EOC cells. Moreover, we have studied various tumorigenic features of the cell lines, such as cell proliferation (by cell count), cell migration (by the wound healing assay), 3D spheroid formation (by the hanging drop method), in vivo tumor formation in SCID mice (subcutaneous xenografts). In general, there were no notable differences between the two categories of cell lines at the cellular level, except that post-chemotherapy cell lines seemed to be unable to form compact 3D structures, contrary to some pre-chemotherapy cell lines. The obtained results would aid in better understanding the different mechanisms that malignant serous EOC tumors undergo and the progression of the disease with respect to the different treatments. Such study would allow us to gain valuable insight into the optimal treatment decisions to take for different EOC patients.
34

Biomarker in Atemluft

Schallschmidt, Kristin 09 June 2017 (has links)
Ein nicht-invasiver Atemtest zur Lungenkrebsdetektion setzt Kenntnis über lungenkrebsspezifische Substanzen voraus. Die Identifizierung von Lungenkrebsbiomarkern in der Atemluft war das Ziel dieser Arbeit. Leichtflüchtige organische Substanzen (VOC) wurden als Zielkomponenten ausgewählt. Für die VOC-Analytik wurde eine SPME-GC-MS-Methode entwickelt und sowohl auf Modellsysteme als auch auf Realproben angewendet. Drei Lungenadenokarzinomzelllinien wurden in-vitro untersucht. Die VOC-Analyse wurde mit drei verschiedenen Probenahmestrategien durchgeführt und es war ein deutlicher Hintergrundeinfluss der eingesetzten Einwegzellkulturflaschen auf das analysierte VOC-Profil feststellbar. Trotzdem konnten signifikante Unterschiede zwischen Tumorzellen und zellfreien Nährmedien beobachtet werden: 1-Propanol wurde von den Zellen produziert, während der Gehalt einiger Aldehyde sank. Die eingeschränkte Ähnlichkeit des gewählten Zellkulturmodells mit realen Atemluftproben bedingt eine geringe Eignung dieser Ergebnisse für die Biomarkerableitung. Ein Gasmodell auf Basis angefeuchteter, synthetischer Luft wurde als Grundlage für die qualitätsgesicherte, quantitative VOC-Analyse der realen Atemluftproben konzipiert. Diese Modellluft wurde mit 24 Zielsubstanzen (Alkane, Aromaten, sauerstoffhaltige Spezies) sowie 3 Matrix-VOC mit starker Dominanz in den Atemluftproben (Isopren, Aceton, 2-Propanol) angereichert. In Kooperation mit zwei Berliner Kliniken wurden 37 Atemluftproben von Lungenkrebspatienten und 23 Proben von Gesunden gesammelt. Die Anwendung von 1-Butanol als univariater Marker erlaubt eine Erkennung von Lungenkrebs mit einer Sensitivität von 92% und Spezifität von 78%. Durch lineare Diskriminanzanalyse konnte ein Set aus 4 VOC (1-Butanol, 2-Butanon, 2-Pentanon, n-Hexanal) ermittelt werden, welches ebenfalls eine Sensitivität von 92% und mit 87% eine höhere Spezifität aufwies. Gegebenenfalls handelt es sich bei diesen Substanzen jedoch nur um allgemeine Krankheitsmarker. / A non-invasive breath test for lung cancer detection would be favorable but knowledge on lung cancer specific substances is required. This work aims at the identification of potential lung cancer biomarkers in breath. Volatile organic compounds (VOC) were chosen as targets and a SPME-GC-MS method was developed to analyze the VOC profiles of model systems and real samples. Three lung adenocarcinoma cell lines were investigated in-vitro. The VOC analysis, carried out with 3 different sampling strategies, was influenced by the VOC background of the used disposable culture vessels. Changes in the VOC profiles of cell lines compared to cell-free culture media were obvious: 1-propanol was released by the tumor cells whereas the content of some aldehydes was diminished. The similarity of this model system with real breath samples of lung cancer patients was seen to be insignificant. Consequently, these cell cultures were not suitable for biomarker identification. A gaseous model consisting of humidified synthetic air was developed. It was fortified with 24 target VOC (alkanes, aromatics and oxygenated species) as well as 3 matrix compounds (isoprene, acetone and 2-propanol) dominating patients’ VOC profiles in breath. This model was used for the quality assured quantitative VOC analysis in real breath samples. In cooperation with two hospitals 37 single mixed expiratory breath samples from lung cancer patients and 23 from healthy controls were collected. Applying 1-butanol as an univariate biomarker patients and controls were discriminated with a sensitivity of 92% and a specificity of 78%. Linear discriminant analysis displayed a set of 4 VOC (1-butanol, 2-butanone, 2-pentanone, n-hexanal) with similar sensitivity but higher specificity of 87%. However, these potential biomarkers might rather be a consequence of illness in general.
35

A Study of the fate and transport of estrogenic hormones in dairy effluent applied to pasture soils

Steiner, Laure D. January 2009 (has links)
The disposal of waste from agricultural activities has been recognised as a source of environmental contamination by endocrine disrupting chemicals (EDCs). The New Zealand dairy industry produces a large volume of dairy farm effluent, which contains EDCs in the form of estrogens. Most of this dairy farm effluent is applied onto the land for disposal. Groundwater and soil contamination by estrogens following waste application on the land have been reported overseas, but our understanding of the processes and factors governing the fate of estrogens in the soil is poor. Therefore the main goal of the present study was to better understand the fate and transport of estrogens, in particular 17β-estradiol (E2) and estrone (E1) in soil. In order to quantify E1 and E2 in drainage water and soil samples, chemical analysis by gas-chromatography mass-spectrometry (GC-MS) was carried out. This included sample extraction, sample clean-up through silica gel and gel permeation chromatography, and sample extract derivatisation prior to analysis. In order to develop a reliable method to extract estrogens from soil, research was conducted to optimise E1 and E2 extraction conditions by adjusting the number of sonication and shaking events, as well as the volume and type of solvent. Among five solvents and solvent mixtures tested, the best recovery on spiked and aged soil was obtained using an isopropanol/water (1:1) mix. A microcosm experiment was carried out to determine the dissipation rates of E2 and E1, at 8°C and at field capacity, in the Templeton soil sampled at two different depths (5-10 cm and 30-35 cm). The dissipation rates decreased with time and half-life values of 0.6-0.8 d for E1 and 0.3-0.4 d for E2 were found for the two depths studied. A field transport experiment was also carried out in winter, over three months, by applying dairy farm effluent spiked with estrogens onto undisturbed Templeton soil lysimeters (50 cm in diameter and 70 cm deep). The hormones were applied in dairy farm effluent at 120 mg m⁻² for E2 and 137 mg m⁻² for E1. The results of the transport experiment showed that in the presence of preferential/macropore flow pathways 0.3-0.7% of E2 and 8-13% of E1 was recovered in the leachate at the bottom of the lysimeters after 3 months, and 1-7% of the recovered E2 and 3-54% of the recovered E1 was leached within 2 days of application. These results suggest that leaching of estrogens via preferential/macropore flow pathways is the greatest concern for groundwater contamination. In the absence of preferential/macropore flow pathways, a significant amount (> 99.94%) of both hormones dissipated in the top 70 cm of soil, due to sorption and rapid biodegradation. Surprisingly, in all cases, estrogen breakthrough occurred before that of an inert tracer (bromide). This could not be explained by the advection-dispersion transport of estrogens, nor by their presence as antecedent concentrations in the soil. It was therefore suggested that colloidal enhanced transport of estrogens was responsible for the earlier breakthrough of estrogens and caused the leaching of a fraction of the applied estrogens to a soil depth of 70 cm. A two-phase model, adapted from a state-space mixing cell model, was built to describe the observed estrogen transport processes under transient flow. The model takes into account 3 transport processes namely, advection-dispersion, preferential/macropore flow and colloidal enhanced transport. This model was able to successfully describe the estrogen transport observed from the lysimeters.
36

Simulation of Unsteady Gas-Particle Flows including Two-way and Four-way Coupling on a MIMD Computer Architectur

Pachler, Klaus, Frank, Thomas, Bernert, Klaus 17 April 2002 (has links) (PDF)
The transport or the separation of solid particles or droplets suspended in a fluid flow is a common task in mechanical and process engineering. To improve machinery and physical processes (e.g. for coal combustion, reduction of NO_x and soot) an optimization of complex phenomena by simulation applying the fundamental conservation equations is required. Fluid-particle flows are characterized by the ratio of density of the two phases gamma=rho_P/rho_F, by the Stokes number St=tau_P/tau_F and by the loading in terms of void and mass fraction. Those numbers (Stokes number, gamma) define the flow regime and which relevant forces are acting on the particle. Dependent on the geometrical configuration the particle-wall interaction might have a heavy impact on the mean flow structure. The occurrence of particle-particle collisions becomes also more and more important with the increase of the local void fraction of the particulate phase. With increase of the particle loading the interaction with the fluid phase can not been neglected and 2-way or even 4-way coupling between the continous and disperse phases has to be taken into account. For dilute to moderate dense particle flows the Euler-Lagrange method is capable to resolve the main flow mechanism. An accurate computation needs unfortunately a high number of numerical particles (1,...,10^7) to get the reliable statistics for the underlying modelling correlations. Due to the fact that a Lagrangian algorithm cannot be vectorized for complex meshes the only way to finish those simulations in a reasonable time is the parallization applying the message passing paradigma. Frank et al. describes the basic ideas for a parallel Eulererian-Lagrangian solver, which uses multigrid for acceleration of the flow equations. The performance figures are quite good, though only steady problems are tackled. The presented paper is aimed to the numerical prediction of time-dependend fluid-particle flows using the simultanous particle tracking approach based on the Eulerian-Lagrangian and the particle-source-in-cell (PSI-Cell) approach. It is shown in the paper that for the unsteady flow prediction efficiency and load balancing of the parallel numerical simulation is an even more pronounced problem in comparison with the steady flow calculations, because the time steps for the time integration along one particle trajectory are very small per one time step of fluid flow integration and so the floating point workload on a single processor node is usualy rather low. Much time is spent for communication and waiting time of the processors, because for cold flow particle convection not very extensive calculations are necessary. One remedy might be a highspeed switch like Myrinet or Dolphin PCI/SCI (500 MByte/s), which could balance the relative high floating point performance of INTEL PIII processors and the weak capacity of the Fast-Ethernet communication network (100 Mbit/s) of the Chemnitz Linux Cluster (CLIC) used for the presented calculations. Corresponding to the discussed examples calculation times and parallel performance will be presented. Another point is the communication of many small packages, which should be summed up to bigger messages, because each message requires a startup time independently of its size. Summarising the potential of such a parallel algorithm, it will be shown that a Beowulf-type cluster computer is a highly competitve alternative to the classical main frame computer for the investigated Eulerian-Lagrangian simultanous particle tracking approach.
37

Caractérisation de nouvelles lignées cellulaires pré-chimiothérapie et post-chimiothérapie du cancer épithélial de l'ovaire

Wang, Lu-Lin 04 1900 (has links)
Le cancer épithélial de l’ovaire (CÉO) est le cancer gynécologique le plus létal. Le CÉO de type séreux, la forme la plus commune avec plus de 50% des cas, est souvent diagnostiqué tardivement et associé à un mauvais pronostic. Le CÉO avancé, surtout traité par chimiothérapie, va devenir chimiorésistant chez la majorité des patientes traitées. Bien que des lignées cellulaires du CÉO aient été dérivées à partir de tumeurs solides et d’ascites de patientes ayant ou non subi une chimiothérapie, aucune des lignées cellulaires du CÉO provenant d’une même patiente avant et après ses traitements de chimiothérapie n’ont été établies précédemment. Notre laboratoire est le premier à développer de telles lignées cellulaires. Nos nouvelles lignées cellulaires sont dérivées de trois patientes différentes (1369, 2295 et 3133) et classées selon leur provenance, soit la tumeur solide (TOV) ou l’ascite (OV). Nous avons donc caractérisé ces nouvelles lignées de cellules pré-chimiothérapie (TOV1369TR, OV2295, TOV3133D et TOV3133G) et post-chimiothérapie (OV1369(2), OV2295(2), TOV2295, OV3133 et OV3133(2)) par diverses approches. Par immunohistochimie et immunobuvardage de type Western, nous avons caractérisé les niveaux d’expression de marqueurs épithéliaux typiques de kératines (KRT7, KRT8, KRT18, KRT19, KRT20) pour confirmer l’origine épithéliale et ovarienne des cellules. Nous avons également analysé le niveau d’expression de HER2 et p53, deux marqueurs importants dans le CÉO. Cependant, il ne semble pas y avoir d’expression différentielle évidente de ces marqueurs entre les lignées pré-chimiothérapie et post-chimiothérapie. Plus encore, nous avons étudié plusieurs caractéristiques tumorigéniques des lignées cellulaires, dont la prolifération cellulaire (par compte cellulaire), la migration cellulaire (par recouvrement de plaie), la capacité à former des sphéroïdes en 3D (par la méthode des gouttelettes inversées), et la formation de tumeurs in vivo dans des souris SCID (xénogreffes sous-cutanées). En général, il ne semble pas y avoir de différences claires entre les cellules pré-chimiothérapie et post-chimiothérapie au niveau du comportement cellulaire, à l’exception du fait qu’aucune des lignées post-chimiothérapie semblent être en mesure de former des structures tridimensionnelles compactes, contrairement à certaines lignées post-chimiothérapie. Nos résultats pourront servir à mieux comprendre les différents mécanismes régissant les tumeurs malignes du CÉO de type séreux et à mieux comprendre la progression de la maladie à travers les différents traitements, ce qui nous permettra d’acquérir des informations essentielles pour mieux évaluer et traiter différentes patientes. / Epithelial ovarian cancer (EOC) is the deadliest of all gynecologic cancers. The serous type of EOC is the most common form of the disease, and it accounts for more than 50% of the cases. It is often diagnosed at advanced stages where its prognosis is poor. Advanced EOC is treated mainly with chemotherapy. However, chemoresistance development eventually impedes the success of the treatments for most patients. Researchers have derived cell lines from EOC from solid tumors or from ascites. So far, there has not been EOC cell lines established from samples taken before and after chemotherapy treatments within the same patient. Our laboratory is thus the first to develop a new and powerful model of pre-chemotherapy and post-chemotherapy cell lines. All cell lines were derived sequentially from 3 different patients (1369, 2295 and 3133), from either solid tumors (TOV) or ascites (OV). We therefore characterized these new pre-chemotherapy cell lines (TOV1369TR, OV2295, TOV3133D and TOV3133G) and post-chemotherapy cell lines (OV1369(2), OV2295(2), TOV2295, OV3133 and OV3133(2)) through several approaches. Using immunohistochemistry and Western blot, we have characterized the level of expression of typical epithelial keratin markers (KRT7, KRT8, KRT18, KRT19, KRT20) to confirm the epithelial and ovarian nature of the cells. We have also analysed the expression level of important EOC markers, such as that of HER2 and p53, and found no clear difference between the pre-chemotherapy and post-chemotherapy EOC cells. Moreover, we have studied various tumorigenic features of the cell lines, such as cell proliferation (by cell count), cell migration (by the wound healing assay), 3D spheroid formation (by the hanging drop method), in vivo tumor formation in SCID mice (subcutaneous xenografts). In general, there were no notable differences between the two categories of cell lines at the cellular level, except that post-chemotherapy cell lines seemed to be unable to form compact 3D structures, contrary to some pre-chemotherapy cell lines. The obtained results would aid in better understanding the different mechanisms that malignant serous EOC tumors undergo and the progression of the disease with respect to the different treatments. Such study would allow us to gain valuable insight into the optimal treatment decisions to take for different EOC patients.
38

Simulation of Unsteady Gas-Particle Flows including Two-way and Four-way Coupling on a MIMD Computer Architectur

Pachler, Klaus, Frank, Thomas, Bernert, Klaus 17 April 2002 (has links)
The transport or the separation of solid particles or droplets suspended in a fluid flow is a common task in mechanical and process engineering. To improve machinery and physical processes (e.g. for coal combustion, reduction of NO_x and soot) an optimization of complex phenomena by simulation applying the fundamental conservation equations is required. Fluid-particle flows are characterized by the ratio of density of the two phases gamma=rho_P/rho_F, by the Stokes number St=tau_P/tau_F and by the loading in terms of void and mass fraction. Those numbers (Stokes number, gamma) define the flow regime and which relevant forces are acting on the particle. Dependent on the geometrical configuration the particle-wall interaction might have a heavy impact on the mean flow structure. The occurrence of particle-particle collisions becomes also more and more important with the increase of the local void fraction of the particulate phase. With increase of the particle loading the interaction with the fluid phase can not been neglected and 2-way or even 4-way coupling between the continous and disperse phases has to be taken into account. For dilute to moderate dense particle flows the Euler-Lagrange method is capable to resolve the main flow mechanism. An accurate computation needs unfortunately a high number of numerical particles (1,...,10^7) to get the reliable statistics for the underlying modelling correlations. Due to the fact that a Lagrangian algorithm cannot be vectorized for complex meshes the only way to finish those simulations in a reasonable time is the parallization applying the message passing paradigma. Frank et al. describes the basic ideas for a parallel Eulererian-Lagrangian solver, which uses multigrid for acceleration of the flow equations. The performance figures are quite good, though only steady problems are tackled. The presented paper is aimed to the numerical prediction of time-dependend fluid-particle flows using the simultanous particle tracking approach based on the Eulerian-Lagrangian and the particle-source-in-cell (PSI-Cell) approach. It is shown in the paper that for the unsteady flow prediction efficiency and load balancing of the parallel numerical simulation is an even more pronounced problem in comparison with the steady flow calculations, because the time steps for the time integration along one particle trajectory are very small per one time step of fluid flow integration and so the floating point workload on a single processor node is usualy rather low. Much time is spent for communication and waiting time of the processors, because for cold flow particle convection not very extensive calculations are necessary. One remedy might be a highspeed switch like Myrinet or Dolphin PCI/SCI (500 MByte/s), which could balance the relative high floating point performance of INTEL PIII processors and the weak capacity of the Fast-Ethernet communication network (100 Mbit/s) of the Chemnitz Linux Cluster (CLIC) used for the presented calculations. Corresponding to the discussed examples calculation times and parallel performance will be presented. Another point is the communication of many small packages, which should be summed up to bigger messages, because each message requires a startup time independently of its size. Summarising the potential of such a parallel algorithm, it will be shown that a Beowulf-type cluster computer is a highly competitve alternative to the classical main frame computer for the investigated Eulerian-Lagrangian simultanous particle tracking approach.
39

A Component-based Model of a Fuel Cell Vehicle System

Salomonsson, David, Eng, Erik January 2021 (has links)
Improving the efficiency and performance of vehicle propulsion systems has always been desirable, and with increasing environmental awareness this has become increasingly topical. A particularly strong focus today is at fossil-free alternatives, and there is a strong trend for electrification. Hybrid powertrains of different types can bring benefits in certain aspects, and there is a lot of research and development involved in the making of a new powertrain. In this thesis, a complete powertrain for a fuel cell hybrid electric vehicle is modeled, with the intention of contributing to this trend. The model can be used to investigate design choices and their impact on energy consumption. A component-based library is developed, with the purpose of being easy to implement for different configurations. The results show that it is possible to assemble and simulate a complete hybrid drivetrain, using the modeled components, while not being very computationally heavy. The developed models correspond well with reality while being modular and easy to implement.
40

Biokonjugate als spezifische Formulierungsadditive für anti-Alzheimer Wirkstoffe

Lawatscheck, Carmen 18 December 2019 (has links)
In der Alzheimer-Forschung (engl.: Alzheimer Disease, AD) wird immenser Aufwand zur Entwicklung von den Krankheitsverlauf verändernden Medikamenten betrieben. Studien zeigten, dass die abnormale Aggregation des Tau-Proteins offenbar zum Zusammenbruch der Zellkommunikation führt. Niedermolekulare Substanzen, die die Tau-Protein-Aggregation inhibieren und sogar bereits gebildete Aggregate wieder auflösen können wurden entwickelt, sind jedoch oft aufgrund von schlechten Wasserlöslichkeiten nur unter Zusatz von Dimethylsulfoxid (DMSO) in Biotests einsetzbar. Durch das Design maßgeschneiderter Peptid-Polyethylenglykol (PEG)-Konjugate war die spezifische Bindung und anschließende Freisetzung ausgewählter potentieller anti-AD-Wirkstoffe in DMSO-freien Biotests möglich. Für den Entwurf der Wirkstoff-Transporter wurden Peptidbibliotheken mit Raman- und Fluoreszenz-Mikroskopie-basierten Methoden hinsichtlich der Anreicherung der Wirkstoffe an Peptiden mit hoher Wirkstoff-Bindekapazität getestet. Mithilfe von Matrix-unterstützter Laser-Desorption/Ionisation (MALDI)-Massenspektrometrie (MS/MS)-Fragmentierung konnten die Peptidsequenzen der positiven Treffer identifiziert werden. Die zugehörigen Konjugate wurden synthetisiert, mit den Wirkstoffen beladen und die entstehenden sehr gut wasserlöslichen Wirkstoff-Konjugat-Komplexe analysiert. Für biomedizinische Anwendungen sind kompakte und definierte Systeme von Vorteil. Zur Strukturaufklärung der Wirkstoff-Konjugat-Komplexe konnten zahlreiche Untersuchungen erfolgreich durchgeführt werden. Viele Komplexe wurden zudem in DMSO-freien Biotests der Tau-Protein-Aggregation eingesetzt. Die Bioverfügbarkeit der schwerlöslichen anti-AD-Wirkstoffe konnte durch die Solubilisierung mit maßgeschneiderten Peptid-PEG-Konjugaten enorm verbessert werden. Die auf Raman-aktive Substanzen erweiterte Screeningprozedur kann wahrscheinlich auf eine Großzahl von Wirkstoffen mit ungünstigen pharmakologischen Eigenschaften angewendet werden. / Considerable efforts are devoted in Alzheimer Disease (AD) research to develop disease modifying drugs. Various studies have demonstrated that abnormal aggregation of Tau protein probably interrupts communication between cells. Tau protein aggregation can be inhibited and even preformed aggregates can be redissolved by small-molecule compounds. Unfortunately, these molecules often can only be applied in limited biotests using dimethyl sulfoxide (DMSO) as co-solvent due to their poor water solubility and bioavailability. The solubilization of selected potential anti-AD drugs by tailored peptide-poly(ethylene glycol) (PEG) conjugates enabled the specific binding und subsequent release of these drugs in DMSO-free biotests. For the design of the drug conjugate carriers, large peptide libraries have been screened using Raman or fluorescence microscopy-based methods to follow drug enrichment on certain peptide library beads which exhibit high drug affinity. Identification of peptide sequences of positive hits was performed by Matrix-assisted Laser Desorption/Ionization (MALDI)-mass spectrometry (MS/MS) fragmentation. The corresponding conjugates were synthesized; loaded with the potential drugs and the resulting highly water-soluble drug transporter complexes were analyzed. Compact and defined complexes are desirable with regard to biomedical applications. Various studies on drug-peptide interactions, specifity of drug binding and influence of the different parts of the conjugates for drug capacities were performed successfully. Generated drug transporter complexes were finally tested in DMSO free bioassays. Depending on drug and peptide structures, the complexes could reach effects comparable to the drugs solubilized by DMSO. The bioavailability of poor water-soluble anti-AD compounds was largely improved. Presumably, the new developed Raman-screening procedure can be expanded to a great extent of compounds suffering from unfavorable pharmacological characteristics.

Page generated in 0.0517 seconds