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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.
41

Desenvolvimento de elementos de fixação (âncoras de suturas) em materiais biocompatíveis através de processo de Manufatura Aditiva / Development of elements of fixation (suture anchor) in biocompatible materials through the process of additive manufacture

Fernando Ferreira Del Monte 01 December 2016 (has links)
Atualmente a área de saúde vem buscando auxílio na engenharia para a contribuição no estudo e confecção de próteses para casos específicos de fraturas ou doenças ósseas. Com o avanço da tecnologia surgiram processos de manufatura que tornam possível a fabricação de próteses personalizadas. Uma dessas tecnologias é a manufatura aditiva. O grande desafio no momento está na fabricação de próteses por manufatura aditiva que combinem desempenho biomecânico e resistência estrutural. Nesse contexto, o objetivo deste trabalho é desenvolver elementos de fixação, especificamente âncoras de sutura de polímeros PEEK e PEKK, considerando seus requisitos estruturais através de simulações pelo método dos elementos finitos, e considerando que sejam fabricadas através de processos de manufatura aditiva. Este desenvolvimento permitirá a substituição de âncoras de sutura de liga de titânio, hoje largamente empregadas pelos cirurgiões, por âncoras de sutura de polímeros biocompatíveis, o que possibilitará que estes polímeros sejam absorvidos pelo corpo humano em curto e médio prazo, permitindo a completa restituição do osso afetado, melhorando a qualidade de vida do paciente pós-cirurgia. Os resultados obtidos neste trabalho indicam que a técnica poderá resultar em próteses com a biocompatibilidade desejada e resistência mecânica adequada. Próteses permanentes (articulações) ou provisórias (âncoras de sutura) seriam um dos critérios para a escolha do material a ser utilizado, absorvível ou não pelo corpo humano. / Nowadays medicine is searching assistance from engineering that may contribute in studies and confection of prothesis to specific cases of fractures and bone diseases. With the advance of technology new processes of manufacture were risen, making possible the confection of personalized prothesis. The biggest challenge of the moment is in the manufacture of additive prothesis that can combine biomechanics performance and structural resistance. In this context, the objective of this dissertation is to develop PEEK and PEKK polymer suture anchors, considering its structural requirements, taking into account their mechanical strength, through simulation by the finite element method, and considering additive manufacturing processes. This development will allow the replacement of titanium alloy suture anchors, now widely used by surgeons by suture anchors of biocompatible polymers, which enable these polymers to be absorbed by the human body in the short and medium term, allowing full regeneration of affected bone, improving the quality of life of the patient. The results of this study indicate that the technique could result in prosthesis with the desired biocompatibility and adequate mechanical strength. Permanent prosthesis (joints) or temporary (suture anchors) would be one of the criteria for the choice of material to be used, absorbable or non absorbable by the human body.
42

Percepção de diferentes modelos de tipoias utilizadas nas lesões dos ombros : design e ergonomia aplicados ao desenvolvimento de produtos para saúde /

Pereira, Diego Dalvan. January 2020 (has links)
Orientador: João Eduardo Guarnetti dos Santos / Resumo: O ombro por ser uma articulação muito instável está mais vulnerável a lesões. Afim de proteger e imobilizar a articulação o tratamento é seguido com o uso de tipoia. No entanto, a imobilização deixa as articulações sob os efeitos deletérios do desuso, o que pode favorecer o surgimento de lesões secundárias como a capsulite adesiva. O design e a ergonomia são considerados disciplinas científicas capazes de desenvolver e ajustar produtos às necessidades e às capacidades humanas. O objetivo deste estudo foi gerar parâmetros para o design ergonômico de uma tipoia alternativa utilizando as tecnologias de manufatura aditiva, a fim de minimizar os desconfortos termofisiológicos e o índice de capsulite adesiva após imobilização. Nesse contexto, desenvolveu-se com o auxílio do design um modelo de tipoia mais confortável, adequado, funcional e que não favorece o surgimento de complicações após imobilização do ombro. Foi realizada uma coleta de dados com indivíduos adultos, de ambos os gêneros, entre 18 e 85 anos de idade, 71 voluntários, que fizeram uso de tipoia para lesão do ombro. Seguiu com uma investigação ergonômica dos modelos de tipoia disponíveis no mercado, para desenvolver um modelo alternativo com as devidas adequações ergonômicas. O projeto da tipoia foi modelado no software CAD SolidWorks e a impressão foi por FDM (Fusão por Deposição de Material), em uma impressora 3D Creality CR-10, com material PLA (Ácido Polilactico). Para testar a percepção do usuário frente aos mode... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The shoulder because it is a very unstable joint is more vulnerable to injury, in order to protect and immobilize the joint, treatment is followed with the use of a sling. However, immobilization leaves the joints under the harmful effects of disuse, which can favor the appearance of secondary lesions such as adhesive capsulitis. Design and ergonomics are considered scientific disciplines capable of developing and adjusting products to human needs and capacities. The aim of this study was to generate parameters for the ergonomic design of an alternative sling using additive manufacturing technologies, in order to minimize thermophysiological discomfort and the adhesive capsulitis index after immobilization. In this context, a more comfortable, adequate, functional tipoia of model was developed with the aid of design, which does not favor the appearance of complications after shoulder immobilization. A data collection was carried out with adult individuals, both genders, between 18 and 85 years of age, 71 volunteers, who made use of tipoia for shoulder injury. It continued with an ergonomic investigation of the sling models available on the market, to develop an alternative model with the appropriate ergonomic adaptations. The design of the tipoia was modeled in SolidWorks CAD software and the printing was by FDM (Melting by Deposition of Material) in a Creality CR-10 3D printer with PLA material (Polylactic Acid). To test the user's perception of sling models, a semantic diff... (Complete abstract click electronic access below) / Doutor
43

Vliv organických aditiv na elektrochemické procesy ovlivňující parametry akumulátorů Zinek-vzduch / Effect of Organic Additives on Electrochemical Processes Influencing Zn-Air Battery parameters

Smejkal, Jan January 2019 (has links)
The diploma thesis is focused on the study of the influence of selected organic additives on the properties and morphology of zinc deposit on the negative electrode when used in zinc-air accumulators. Organic additives have been selected based on the study of literature and previously done experiments. The deposition was made on the tin plate electrodes in a solution of 6 mol/l KOH saturated with ZnO with added additives. All chosen additives were studied with a focus on the morphology of zinc deposit and with regard to their ability to suppress dendritic growth. Zinc morphology was studied by using a Tescan Vega 3 electron microscope and a Rigaku MiniFlex HR 600 X-ray diffractometer.
44

Mikroskopická pozorování struktur aktivní hmoty záporné elektrody olověného akumulátoru / Microscopic Observations of Active Mass Structures of the Negative Electrode of a Lead-Acid Battery

Zimáková, Jana January 2020 (has links)
This doctoral dissertation deals with the study of the effect of additives on the properties of the negative electrode of a lead-acid battery. The work focuses on the investigation of the additive/base material interface for the negative electrode (so-called active mass) using atomic force microscopy (AFM). A lead sheet was used as the base material, on which the given additive was applied. The effects of carbon, TiO2, glass fibers and Indulin AT were specifically investigated. The negative electrode was cycled by a potentiostat in a defined manner and the morphology of the electrode surface was continuously scanned by AFM. This created a time sequence of images on which events on the surface of the electrode during its charging/discharging were captured. These records serve to better understand the effect of additives on the resulting properties of constructed lead-acid cells, specifically on the ability to form or dissolve PbSO4 crystals, which are formed during cell discharge and are responsible for the decrease in total capacity - gradual surface sulfation.
45

Studium chování detonovaného nanodiamantu dispergovaného v mazivech / Tribological behavior of detonation nanodiamond dispersed in lubricants

Dočekal, Martin January 2016 (has links)
Currently tribological laboratories are looking for a new type of solid ingredients, to create a lubricating composition with minimal friction, heat resistant, with particles well dispersed in oils, sedimentation stable, improving the running properties and to minimize the concentration of solids. Nanodiamonds (DND) could exhibit the possible solution. These particles (in nanometers size) have very good physical and chemical properties, high hardness and resistance. The main advantages are effectiveness at low concentrations, compatibility with various types of oils or environmental safety (carbon additive, unlike metal) in a comparison with other types of additives. However, it is necessary to study these ingredients. The aim of research was to examine the influence of diamond nanoparticles on friction in a lubricated contact (elastohydrodynamic mode). Using tribological equipment, 3D optical profilometer and a microscope, we compared and evaluated using oil with diamond nanoparticles as well as without them. The research focused on the behavior of nanoparticles in contact and the effect they have on friction. To assess these properties of nanodiamonds, EHD optical tribometer was used (this is a device designed for the study of thin lubricating films). 3D optical profilometer and a microscope to assess the wear. And to determine the relationship between the coefficient of friction (COF) and time, Mini Traction Machine was used.
46

Vliv aditiv na elektrické vlastnosti epoxidových pryskyřic / Additives effect on electrical properties of the epoxy resins

Šebesta, Petr January 2016 (has links)
Work was carried out in collaboration with SYNPO, Inc. Pardubice, which provided samples resins with various additives for measurement. The work is divided into three theoretical and one practical chapters. The first chapter focuses on dielectrics in general. It deals with their properties and storyline running in them. The second chapter discusses epoxy resins, their formulation, production and application in manufacturing. The third chapter offers a view of the measurement methods used for diagnosing electrical dielectrics. The practical part describes the preparation of samples and their composition, and consequently their measurement with the evaluation of measurement data.
47

Analýza organických příměsí v historických maltových materiálech / Analysis of organic additives in historical mortars

Křížová, Iva January 2012 (has links)
- 4 - Abstrakt The aim of this diploma thesis was to determine the possibility of identifying the protein and lipid additives, such as blood, gelatine, curd, lard and eggs, in the model samples of lime based mortars using Raman spectroscopy and gas chromatography- mass spectrometry. It was proved that the method of Raman spectroscopy can determine the presence of organic additives in the order of one weight percent. The gas chromatography enables to detect lipid additives from the order of hundredths weight percent. Unambiguous resolution of protein additives can be done in the samples with the concentrations up to the order of one weight percent of the additives.
48

Vliv aditiv na kvalitu a zdravotní bezpečnost siláží jetelovin

Florianová, Viola January 2018 (has links)
The aim of this diploma thesis was to compare quality of protein silages made of lucerne (Medicago sativa L.) (there were used two varieties Holyna and Tereza) and red clover (Trifolium pratense L.) (tetraploid variety Amos and diploid variety Spurt) ensiled with low dry matter content 16–20 %. Experimental parcels were founded in 2013. Plots of lucerne were harvested for three following years, plots of red clover were harvested for two following years. Green feed was ensiled into laboratory microsilos directly after harvesting. The silage quality was compared within species and variety and within different silage additives. There were analyzed contents of organic nutrients, digestibility in green material and organic nutrients, digestibility, quality of silage extracts, losses and amount of silage effluents in silages. Silages made of red clover had significantly (p <0,05) lower pH, ammonia content, content of butyric acid and proteolysis level compared to lucerne silages. Amos variety had also significantly higher content of lactic acid compared to both lucerne silages. The effect of chemical silage additive on silage quality was significant. Silages treated with chemical additive had significantly lower (p <0,05) pH, ammonia content, content of acetic acid, ethanol and level of proteolysis compared to untreated variant and variant treated with biological additive.
49

Hodnocení kvality siláží vyrobených z pícnin čeledi lipnicovitých

Richterová, Bára January 2019 (has links)
The thesis is focused on the assessment of the quality of the fermentation process in various grass species. In the literary part we characterize grasses of the family Poaceae. The next part is devoted to the conservation of silage grasses with possible threats to ensilage and the use of silage additives in production. In the practical part, a total of 12 grass samples were monitored. They were founded in two variants, fertilized and non-fertilized with nitrogen, treated and untreated with silage additive. Grasses were harvested from the microsilage vessels after 60 days and analyzed for selected parameters. The results were evaluated by graphs. Ammonia, pH, LA, AA, biogenic amines were further processed by ANOVA. Using the values from the analyzes, we evaluated the quality of the fermentation process, when the samples of festulolium, festulolium N were the best, among which there was a statistically significant difference at 95 % confidence level. In the analytical evaluation the worst sample of the lobed fur without treatment was found to have poor quality silage fermentation. It also contained the most biogenic amines but there were no statistically significant differences between the samples (p <0.05). For samples of the lobed foot treated with a chemical additive, we can conclude that the use of the chemical preservative SoftAcid improved the quality of the fermentation.
50

Manufatura aditiva de scaffolds estruturados recobertos com látex para regeneração óssea /

Marcatto, Vinícius Assis January 2020 (has links)
Orientador: Gustavo Franco Barbosa / Resumo: O desempenho de tecidos e órgãos de todo organismo vivo, fica naturalmente comprometido com o passar dos anos, e se faz necessário intervenções médicas para eventuais reconstituições ou reparações de tecidos acometidos e danificados por doenças ou lesões. Neste contexto, a Engenharia Tecidual tem trabalhado de maneira interdisciplinar nos campos das Engenharias, Biologia e Medicina, e tem trazido grandes evoluções e opções aos já difundidos transplantes e enxertos ósseos. Nesse âmbito, impulsionado pelas recentes aplicações da tecnologia da manufatura aditiva, novos polímeros termoplásticos biodegradáveis têm sido utilizados com sucesso. Dessa forma, este trabalho de pesquisa tem como propósito principal desenvolver scaffolds 3D mimetizando o osso trabecular, aliando as propriedades de biocompatibilidade e biodegradabilidade do já difundido e certificado PLA (ácido polilático). Assim, os scaffolds 3D de PLA em sua versão comercial, são recobertos com látex natural extraído da Hevea brasiliensis por meio da técnica dip-coating, afim de otimizar a biocompatibilidade, promovendo condições para a angiogênese e proporcionando condições para a migração, diferenciação e proliferação de tecido ósseo, características estas que foram detectadas em estudos recentes deste material com resultados promissores. Com auxílio de softwares CAD, foi possível desenvolver geometrias com interconectividade estruturada, seguidos de definição de parâmetros de processamento e fabricação utilizando a t... (Resumo completo, clicar acesso eletrônico abaixo) / Mestre

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