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Nanoparticels from brake pads wear
Švábenská, Eva ; Roupcová, Pavla ; Friák, Martin ; Schneeweiss, Oldřich
Exposure to particulate air pollution has been associated with a variety of health problems. One of the main\nsources of metal-rich airborne particulate pollution in roadside environments are brake-wear emissions. The \nscanning electron microscopy (SEM) and transmission electron microscopy (TEM), Mössbauer spectroscopy \n(MS), X-ray powder diffraction (XRD) was used to a make quantitative evaluation of wear particles in two \nsamples. Sizes, morphologies, oxidation state, and trace element compositions of wear particles were\ninvestigated using combination of several methods revealed high concentrations of Fe species and phases, \noften associated with carbonaceous material. SEM and TEM observations show that brake wear particles with \na size of tens to hundreds of nm mainly form particle agglomerates. However, ultrafine (<100 nm) particles are \nlikely to pose a health threat after inhalation and/or ingestion.
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Image analysis in tribodiagnostics
Machalík, Stanislav ; Stodola,, Jiří (referee) ; Tillová,, Eva (referee) ; Zemčík, Pavel (advisor)
Image analysis of wear particles is a suitable support tool for detail analysis of engine, gear, hydraulic and industrial oils. It allows to obtain information not only of basic parameters of abrasion particles but also data that would be very difficult to obtain using classical ways of evaluation. Based on the analysis of morphological or image characteristics of particles, the progress of wearing the machine parts out can be followed and, as a result, possible breakdown of the engine can be prevented or the optimum period for changing the oil can be determined. The aim of this paper is to explore the possibilities of using the image analysis combined with the method of analytical ferrography and suggest a tool for automated particle classification. Current methods of wear particle analysis are derived from the evaluation that does not offer an exact idea of processes that take place between the friction surfaces in the engine system. The work is based upon the method of analytical ferrography which allows to evaluate the state of the machine. The benefit of use of classifiers defined in this wirk is the possibility of automated evaluation of analytical ferrography outputs; the use of them eliminates the crucial disadvantage of ferrographical analysis which is its dependence on the subjective evaluation done by the expert who performs the analysis. Classifiers are defined as a result of using the methods of machine learning. Based on an extensive database of particles that was created in the first part of the work, the classifiers were trained as a result, they make the evaluation of ferrographically separated abrasion particles from oils taken from lubricated systems possible. In the next stage, experiments were carried out and optimum classifier settings were determined based on the results of the experiments.
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Polyethylene wear particles around joint replacements - their properties, distribution and possible mechanism of their adverse biological effects
Zolotarevová, Eva ; Gallo, Jiří (advisor) ; Rauch, Pavel (referee) ; Horák, Zdeněk (referee)
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...
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Polyethylene wear particles around joint replacements - their properties, distribution and possible mechanism of their adverse biological effects
Zolotarevová, Eva
This PhD thesis in essence rounds off the range of queries asked several years ago when the task was set by Doc. RNDr. Zdenek Horak, PhD. The original isolation procedure for polyethylene wear particles, identification of some of their physico-chemical properties and manipulation accordingly has been successful in the process of this thesis accomplishment. It became possible to quantify the particles at relative as well as absolute scale. The thesis managed to disprove the published opinion that centrifugation can affect the morphology of isolated particles. The issue of distribution of polyethylene wear particles around hip endoprothesis has been solved at two levels: "macroscopically", the distribution of wear particles in zones around endoprosthesis was showed (this thesis does not include these data). Furthermore, at the "microscopic" level, the distribution of wear particles in granuloma tissue from the zones surrounding endoprostheses with most particles has been determined. The granuloma tissue formed in zones with most particles because of that. It was observed that the common term - osteoagressive granuloma - used by orthopedist is rather misguided. Granuloma is not aggressive to bone tissue. On the contrary, the granuloma formation reduces the effective amount of wear particles with...
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Polyethylene wear particles around joint replacements - their properties, distribution and possible mechanism of their adverse biological effects
Zolotarevová, Eva
This PhD thesis in essence rounds off the range of queries asked several years ago when the task was set by Doc. RNDr. Zdenek Horak, PhD. The original isolation procedure for polyethylene wear particles, identification of some of their physico-chemical properties and manipulation accordingly has been successful in the process of this thesis accomplishment. It became possible to quantify the particles at relative as well as absolute scale. The thesis managed to disprove the published opinion that centrifugation can affect the morphology of isolated particles. The issue of distribution of polyethylene wear particles around hip endoprothesis has been solved at two levels: "macroscopically", the distribution of wear particles in zones around endoprosthesis was showed (this thesis does not include these data). Furthermore, at the "microscopic" level, the distribution of wear particles in granuloma tissue from the zones surrounding endoprostheses with most particles has been determined. The granuloma tissue formed in zones with most particles because of that. It was observed that the common term - osteoagressive granuloma - used by orthopedist is rather misguided. Granuloma is not aggressive to bone tissue. On the contrary, the granuloma formation reduces the effective amount of wear particles with...
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Polyethylene wear particles around joint replacements - their properties, distribution and possible mechanism of their adverse biological effects
Zolotarevová, Eva ; Gallo, Jiří (advisor) ; Rauch, Pavel (referee) ; Horák, Zdeněk (referee)
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...
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Image analysis in tribodiagnostics
Machalík, Stanislav ; Stodola,, Jiří (referee) ; Tillová,, Eva (referee) ; Zemčík, Pavel (advisor)
Image analysis of wear particles is a suitable support tool for detail analysis of engine, gear, hydraulic and industrial oils. It allows to obtain information not only of basic parameters of abrasion particles but also data that would be very difficult to obtain using classical ways of evaluation. Based on the analysis of morphological or image characteristics of particles, the progress of wearing the machine parts out can be followed and, as a result, possible breakdown of the engine can be prevented or the optimum period for changing the oil can be determined. The aim of this paper is to explore the possibilities of using the image analysis combined with the method of analytical ferrography and suggest a tool for automated particle classification. Current methods of wear particle analysis are derived from the evaluation that does not offer an exact idea of processes that take place between the friction surfaces in the engine system. The work is based upon the method of analytical ferrography which allows to evaluate the state of the machine. The benefit of use of classifiers defined in this wirk is the possibility of automated evaluation of analytical ferrography outputs; the use of them eliminates the crucial disadvantage of ferrographical analysis which is its dependence on the subjective evaluation done by the expert who performs the analysis. Classifiers are defined as a result of using the methods of machine learning. Based on an extensive database of particles that was created in the first part of the work, the classifiers were trained as a result, they make the evaluation of ferrographically separated abrasion particles from oils taken from lubricated systems possible. In the next stage, experiments were carried out and optimum classifier settings were determined based on the results of the experiments.
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UHMWPE failure in knee joint component
Franta, L. ; Jeníková, Z. ; Pražák, Josef ; Suchánek, J.
A simulation of realistic tribologic conditions in tests “in vitro”contributes significantly to the research in the field of joint replacements. Motion under low relative velocities of friction surfaces of knee joint replacements is studied. The simulator enabled combination of rolling and sliding motion of replacement components. During the experiment, numerous debris of UHMWPE component ares produced and the friction surface is irreversibly changed. Initially, the irregularities of tibial component are smoothed. Consequently, large amount of UHMWPE debris is released. Specimens were loaded for 15.105 cycles with dry or distilled water lubrication. The surface changes of specimens were evaluated.
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