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  • 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.
11

Eine biomechanische Untersuchung der Einreihenrefixation im Vergleich zur Doppelreihenrefixation bei der Rekonstruktion von Rotatorenmanschettenrupturen unter Berücksichtigung des Nahtmaterials und der Nahttechnik / Biomechanical characteristics of single-row repair in comparison to double-row repair with consideration of the suture configuration and suture material

Poppendieck, Björn 09 November 2011 (has links)
No description available.
12

Plazmová modifikace práškových materiálů / Plasma modification of powder materials

ČERNÝ, Pavel January 2011 (has links)
Thesis is focused on plasma modification of materials. The work has the character of a search of available literature, especially the papers presented in impacted journals. The aim is to provide a broader overview of the subject. The first section describes the most commonly modified powdered materials. The second part is focused on the plasma modification, the reasons for its use, capabilities and benefits respectively and disadvantages of these processes. The following sections are devoted to plasma discharges, plasma reactors, aspects of plasma modification and companies engaged in production, or modification of powders. Each chapter is intended to provide an overview of the modified powder materials, processes within the plasma discharges, construction and use of plasma reactors, plasma modification of aspects and the market situation in the context of powdered materials and companies dealing with the plasma modification.
13

Využití polymerů do konstrukcí vozovek pozemních komunikací / Use of polymers in road constructions

Klusková, Jana January 2020 (has links)
The diploma thesis deals with the use of recycled polymers in asphalt mixtures. In the theoretical part of the thesis there is discussed the global issue of plastic waste including the experience of foreign countries, where this technology has already been introducted and used. The practical part is devoted to the proposal of using recycled plastic in asphalt mixture, description of used laboratory tests and the evaluating the effect of low-density polyethylen (LDPE) on the asphalt mixture type AC. There were performed tensile strenght tests, water resistant tests and stiffness modulus tests in the laboratory (E). The output of this work is an evaluation of measured values, processing of results and their interpretation depending on the possible use of this technology in Czech republic.
14

Otěrové částice polyethylenu v okolí kloubních náhrad - jejich vlastnosti, distribuce a možný mechanizmus jejich nežádoucího biologického působení / Polyethylene wear particles around joint replacements - their properties, distribution and possible mechanism of their adverse biological effects

Zolotarevová, Eva January 2010 (has links)
CHARLES UNIVERSITY IN PRAGUE FACULTY OF SCIENCE DEPARTMENT OF BIOCHEMISTRY PRAGUE 2010 Supervisor: Doc. MUDr. Jiří Gallo, PhD. Supervisor-consultant: Prof. RNDr. Gustav Entlicher, CSc. Eva Zolotarevová Summary of PhD Thesis POLYETHYLENE WEAR PARTICLES AROUND TOTAL JOINT REPLACEMENTS - THEIR PROPERTIES, DISTRIBUTION AND POSSIBLE MECHANISM OF THEIR ADVERSE BIOLOGICAL EFFECTS PRAGUE 2010 The research project was supported by the Grant project of National research program II. (no. 2B06096) of the Czech Ministry of Education, Youth and Sports named "Observation and minimization of UHMWPE wear in joint replacements". Front-page picture: Polyethylene wear particle isolated from granuloma tissue surrounding total hip replacement; Electron microscope microphotograph; particle size app. 90 x 80 µm; retouched Eva Zolotarevová Introduction Introduction For many people all over the world a replacement with an implant of irreversibly damaged joint is often the only way how to come back to normal life without pain and mobility limitation. Nowadays, greater and greater requirements are asked of quality of all replacement components, especially in terms of quality of used materials. Biomechanical properties of hip and knee replacements have been already solved. The most often used materials for manufacturing joint...
15

Nanostrukturované plazmové polymery pro řízenou imobilizaci biomolekul / Nano-structured multicomponent plasma polymers for controlled immobilization of biomolecules

Melnichuk, Iurii January 2017 (has links)
Title: Nano-structured multicomponent plasma polymers for controlled immobilization of biomolecules Author: Iurii Melnichuk Department / Institute: Department of Macromolecular Physics/Charles University Supervisor of the doctoral thesis: Doc. Ing. Andrey Shukurov, Ph.D. Abstract: The aim of this thesis is to highlight the feasibility of tailored nano- structures in functionalizing surfaces for biointerfacial interactions. Development of new techniques for the production of nanoscaled biomaterials can be of use in a variety of medical and biological applications, e.g. biosensors, microarrays, drug sensors, implants, blood-contacting devices. This thesis first examines the early stages of nano-structured thin film growth fabricated by vapor phase deposition of poly(ethylene). We discuss island growth within a framework of rate equation theory, dynamic scaling theory and capture zone distribution. In a second stage, we test dielectric barrier discharge to activate PE nano-pattern for covalent immobilization of proteins. Finally, we assess cell behavior on surfaces in dependence on morphology and the presence of cell adhesive protein tropoelastin. We employ plasma polymerization to produce ultrathin hydrocarbon layer capable of protein anchoring. The thesis findings for the first time manifest the critical...
16

Potentials and limitations of welding incompatible polymers

Albrecht, Mirko, Hüllmann, André, Gehde, Michael 07 March 2018 (has links)
Due to the wide range of properties of plastics (e.g. low density, low electrical and thermal conductivity), conventional materials will be increasingly substituted by polymers. Multifarious requirements on technical parts intensify the demand for joining processes, which ensure the reliable joining of incompatible thermoplastics. In this case, material bonded joints are approaching their limits. The present study focusses on the welding of two incompatible thermoplastic polymers (polyamide and polyethylene) by using adapted blend materials, which are compatible to both joining components. The results prove the feasibility of this method and indicate the high potential regarding the reachable joint strength. Furthermore, the study demonstrates the challenges regarding the suitable application of blend materials and deals with open scientific questions concerning their industrial usage.
17

Využití polymerů do konstrukcí vozovek pozemních komunikací / Use of polymers in road constructions

Klusková, Jana Unknown Date (has links)
The diploma thesis deals with the use of recycled polymers in asphalt mixtures. In the theoretical part of the thesis there is discussed the global issue of plastic waste including the experience of foreign countries, where this technology has already been introducted and used. The practical part is devoted to the proposal of using recycled plastic in asphalt mixture, description of used laboratory tests and the evaluating the effect of low-density polyethylen (LDPE) on the asphalt mixture type AC. There were performed tensile strenght tests, water resistant tests and stiffness modulus tests in the laboratory (E). The output of this work is an evaluation of measured values, processing of results and their interpretation depending on the possible use of this technology in Czech republic.
18

Oberflächenmodifizierung von textilem ultrahochmolekularen Polyethylen mittels Dielektrischer Barriereentladung / Surface modification of textile ultra-high-molecular-weight polyethylene via dielectric barrier discharge

Bartusch, Matthias 06 September 2016 (has links) (PDF)
Textiles ultrahochmolekulares Polyethylen (UHMWPE) besitzt, aufgrund seiner außerordentlich hohen Molmasse und einem kristallinen Anteil von mehr als 80 %, exzellente spezifische Reißfestigkeiten sowie sehr gute Beständigkeiten gegenüber biologischen, chemischen und physikalischen Einflüssen, wodurch es sich für den Einsatz in Schutztextilien, als textiler Träger für funktionelle Partikel, zur Faserverstärkung in Kunststoffen für hochbelastbare Bauteile und auch zur Herstellung hochwertiger, technischer Textilmembranen anbietet. Voraussetzung für diese Applikationen ist ein hohes Wechselwirkungsvermögen der Fasergrenzflächen. Im Rahmen dieser Dissertationsschrift wurden systematisch die Möglichkeiten zur Oberflächenaktivierung von textilem UHMWPE mittels Atmosphärendruckplasma (ADP) untersucht und Eigenschafts-Wirkungsbeziehungen verschiedener Einflussparameter, u. a. Plasmaleistung, Elektrodenabstand, Behandlungsintensität, aufgeklärt. Dabei lag ein besonderes Augenmerk auf den textilen Eigenheiten des Materials und der dadurch stark beeinflussten Durchdringung des Plasmas. Entsprechend wurden umfangreiche Messreihen zu chemischen und physikalischen Veränderungen der Faseroberfläche erstellt, um schließlich eine industrielle Nutzbarkeit der ADP-Behandlung ableiten zu können. Hierzu wurden auch zwei weitere Verfahren vergleichend begutachtet und in Kooperation mit dem Leibniz-Institut für Polymerforschung Dresden e.V. eine mögliche Anwendung aktivierter UMHWPE-Garne als Träger für magnetisierbare Nanopartikel betrachtet.
19

Analýza působení termoplastových potrubí v zemním prostředí / Analysis of Thermoplastic Pipes in a Soil Environment

Ekr, Jan January 2019 (has links)
The doctoral thesis deals with an analysis of thermoplastics pipes in a soil environment, in particularly, pipes performed by using trenchless technologies. In the doctoral thesis, experiments of polyethylene pipes loaded by external hydrostatic pressure were performed. The aim of the experiments was to determine a behaviour and load-bearing capacity of the polyethylene pipes loaded by external hydrostatic pressure. For the experiments, a steel pressure chamber was designed and produced which allowed loading and observing a pipe during its loss of the stability. Mechanical properties of the pipe material were determined based on the tensile and bending tests. The series of detailed numerical analyses of the pipe experiments were performed. Various material models which take into account elastic, plastic and viscous behaviour of thermoplastic materials were used. In addition, series of standardized calculations of polyethylene pipes installed using trenchless technologies were performed. The aim was to create new design diagrams for practical assessment of these pipes placed in the partially deteriorated old pipes. In the case of the deteriorated old pipe, a numerical model for determination of design coefficients was created. These design coefficients were verified with standard values. Then, the results of the numerical model were compared with the results of the more complex numerical model which better take into account pipe-soil interaction of various soil types.
20

Structural investigations using small angle scattering techniques and contrast variation

Rabe, Christian 30 March 2015 (has links)
Die Analyse der Röntgen- und Neutronenkleinwinkelstreuung stellt ein ideales Werkzeug für Untersuchungen der Struktur submikroskopischer Teilchen und deren Wechselwirkungen dar. Hierbei eröffnet die Variation des Streukontrastes ein zusätzliches Spektrum an Informationen. Wie in der vorliegenden Arbeit gezeigt wird, kann durch die Verwendung komplementäre Verfahren ein detailliertes Bild der untersuchten Systeme erarbeitet werden. Im Fokus der Diskussion stehen Polyethylennanopartikel und Strukturen basierend auf hyperverzweigtem Polyglycerol. Die durchgeführten Untersuchungen liefern beispielsweise Rückschlüsse auf den Mechanismus, der zu einer nahezu idealen Anordnung unverzweigter Polymerketten, während der Bildung der Polyethylennanopartikel, führt. Im amorphen Anteil dieser plättchenförmigen Partikel findet demnach ausschließlich eine Richtungsänderung beim Wiedereintritt der Polymerketten in die kristalline Phase statt, wodurch eine ungehinderte Kettendiffusion möglich ist. Der Einfluss von Defekten entlang der Polymerkette auf die Partikelstruktur konnte durch Untersuchungen eines präzise verzweigten Polyethylens ermittelt werden. Bei weiteren Untersuchungen von wässrigen Dispersionen eines hyperverzweigten Polyglycerols konnte die übergeordnete Struktur als Fraktal beschrieben werden. Der signifikante Beitrag der Mikrostrukturierung des Moleküls zu dessen Kleinwinkelstreuung wurde in den Analysen berücksichtigt. Die Strukturuntersuchungen von Molekülen mit dem polaren hyperverzweigten Kern und einer nahezu vollständigen Funktionalisierung durch bipolare Ketten profitierte von diesen Ergebnissen. Hierbei wurde die Struktur dieser Moleküle in polaren und unpolaren Medien ermittelt. In einer polaren Umgebung wurde die Bildung von Assoziaten beschrieben. Dies liefert wertvolle Hinweise auf die Wirkungsweise als Wirkstofftransportsystem liefert. / The analysis of the small angel X-Ray and neutron scattering is an ideal tool for the discussion of the structure and interactions of submicroscopic particles. Herein, the variation of the scattering contrast enlarges the spectrum of information, additionally. As shown in the presented work, complementary probes give a detailed picture of the investigated systems. The focal point of the discussion is set on polyethylene nanoparticles and structures based on hyperbranched polyglycerol. The analyses provide, for instance, information on the mechanism that leads to an ideal arrangement of the non-branched polymer chains during the formation of the platelet-like polyethylene nanoparticles. The amorphous phase exclusively hosts the redirection of the polymer chains into the crystalline domain. This allows the unimpeded chain diffusion. The effect of defects along the polymer chain on the particle structure was studied by the analyses of polyethylene with precisely placed methyl groups. Analyses of aqueous dispersions of hyperbranched polyglycerol reveal the fractal-like character of the global molecule structure. Additionally, the significant contribution of the molecule’s microstructure to the corresponding small angle scattering was considered. The analyses of molecules composed of the hyperbranched core and a complete functionalisation with bipolar chains profited from these results. Hereby, the molecule structure in polar and non-polar media was identified. In polar surrounding the formation of well-defined aggregates was described. This provides essential information for a further discussion of this type of molecules as drug delivery platform.

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