Design and validation of a biomechanical bioreactor for cartilage tissue culture

Specific tissues, such as cartilage undergo mechanical solicitation under their normal performance in human body. In this sense, it seems necessary that proper tissue engineering strategies of these tissues should incorporate mechanical solicitations during cell culture, in order to properly evaluate the influence of the mechanical stimulus. This work reports on a user-friendly bioreactor suitable for applying controlled mechanical stimulation - amplitude and frequency - to three dimensional scaffolds. Its design and main components are described, as well as its operation characteristics. The modular design allows easy cleaning and operating under laminar hood. Different protocols for the sterilization of the hermetic enclosure are tested and ensure lack of observable contaminations, complying with the requirements to be used for cell culture. The cell viability study was performed with KUM5 cells.

Connecting free volume with shape memory properties in noncytotoxic gamma-irradiated polycyclooctene

The free volume holes of a shape memory polymer have been analysed considering that the empty space between molecules is necessary for the molecular motion, and the shape memory response is based on polymer segments acting as molecular switches through variable flexibility with temperature or other stimuli. Therefore, thermomechanical analysis (TMA) and positron annihilation lifetime spectroscopy (PALS) have been applied to analyse shape recovery and free volume hole sizes in gamma irradiated polycyclooctene (PCO) samples, as a non-cytotoxic alternative to more conventional PCO crosslinked via peroxide for future applications in medicine. Thus, a first approach relating structure, free volume holes and shape memory properties in gamma irradiated PCO is presented. The results suggest that free volume holes caused by gamma irradiation in PCO samples facilitate the recovery process by improving movement of polymer chains and open t possibilities for the design and control of the macroscopic response.

Influence of design parameters on the mechanical behavior and porosity of braided fibrous stents

In spite of all innovations in stent design, commonly used metallic stents present several problems such as corrosion, infection and restenosis, leading to health complications or even death of patients. In this context, the present paper reports a systematic investigation on designing and development of 100% fiber based stents, which can eliminate or minimize the problems with existing metallic stents. For this purpose, braided stents were produced by varying different materials, structural and process parameters such as mono-filament type and diameter, braiding angle and mandrel diameter. The influence of these design parameters on mechanical behavior as well as stent's porosity was thoroughly investigated, and suitable parameters were selected for developing a stentwith mechanical characteristics and porosity matching with the commercial stents. According to the experimental results, the best performance was achieved with a polyester stent designed with 0.27 mm monofilament diameter, braiding angle of 35° and mandrel diameter of 6 mm, providing similar properties to commercial Nitinol stents.

Design de superfície biomimética para aplicação em atividades desportivas

Tese de Doutoramento Engenharia Têxtil.

Re-Design of ribbon for new applications

O conceito de qualidade de vida surge pela primeira vez em 1920, através do economista inglês Arthur Cecil Pigou, que utiliza este termo para descrever o impacto governamental sobre a vida das pessoas mais desfavorecidas. Com a instalação de uma era industrializada e com o fim da 2º Guerra Mundial, a sociedade mudou de paradigma e iniciou uma procura incessante de formas para melhorar a sua qualidade de vida. Este conceito desenvolve-se juntamente com o desenvolvimento do conceito de educação, saúde, habitação, transporte, trabalho e lazer, bem como indicadores do aumento da esperança de vida, a diminuição da mortalidade infantil e dos níveis de poluição. O avanço da tecnologia teve um papel fundamental para a evolução desses conceitos, bem como o Design na procura de soluções para aplicação dessas mesmas tecnologias. No caso concreto da indústria tèxtil, a tendência é o desenvolvimento de têxteis inteligentes envolvendo a engenharia electrónica no seu processo de conceptualização e de fabrico. A chamada tecnologia wearable abre novos horizontes para a criação de soluções inovadoras, abrindo novos nichos de mercado com elevado valor acrescentado. Existem atualmente vários produtos no mercado cuja funcionalidade e utilidade lhes conferiu um estatuto imutável ao longo dos anos, onde a evolução não avançou na tendência atual. Esse é o caso dos tecidos estreitos, cuja funcionalidade poderá adquirir novas capacidades e ser utilizada em diferentes componentes têxteis nas mais variadas áreas. Essas capacidades poderão ser acrescentadas pela incorporação de materiais com luminosidade (Led’s e L-Wire) nas suas estruturas. Neste estudo realizado o design de produtos com novas funcionalidades, adaptando as tecnologias até agora desenvolvidas em novas soluções e/ou novas recriações de produto.

Design of assemblies based on polymer-coated quantum dots and organic dye

During last years, photophysical properties of complexes of semiconductor quantum dots (QDs) with organic dyes have attracted increasing interest. The development of different assemblies based on QDs and organic dyes allows to increase the range of QDs applications, which include imaging, biological sensing and electronic devices.1 Some studies demonstrate energy transfer between QDs and organic dye in assemblies.2 However, for electronic devices purposes, a polymeric matrix is required to enhance QDs photostability. Thus, in order to attach the QDs to the polymer surface it is necessary to chemically modify the polymer to induce electronic charges and stabilize the QDs in the polymer. The present work aims to investigate the design of assemblies based on polymer-coated QDs and an integrated acceptor organic dye. Polymethylmethacrylate (PMMA) and polycarbonate (PC) were used as polymeric matrices, and nile red as acceptor. Additionally, a PMMA matrix modified with 2-mercaptoethylamine is used to improve the attachment between both the donor (QDs) and the acceptor (nile red), as well as to induce a covalent bond between the modified PMMA and the QDs. An enhancement of the energy transfer efficiency by using the modified PMMA is expected and the resulting assembly can be applied for energy harvesting.

Metodologias facilitadoras da criatividade em design de moda: uma experiência académica

Este artigo descreve a experiência prática de um trabalho realizado em sala de aula, que trata de agregar técnicas facilitadoras do desenvolvimento da criatividade, num processo de criação de moda. O método usado foi adaptado para o design de moda, através da utilização das técnicas de “brainstorming”, “mapas mentais” e “painéis semânticos” conjugados num exercício prático-experimental de criatividade. O objetivo deste estudo consiste em analisar o desempenho criativo dos alunos e as possibilidades resultantes da utilização e adaptação de tais metodologias de criatividade em design de moda.

Design modular: Solução sustentável aplicada aos resíduos limpos na indústria do couro

ISSN 19820941

Testing Nelder-Mead based repulsion algorithms for multiple roots of nonlinear systems via a two-level factorial design of experiments

This paper addresses the challenging task of computing multiple roots of a system of nonlinear equations. A repulsion algorithm that invokes the Nelder-Mead (N-M) local search method and uses a penalty-type merit function based on the error function, known as 'erf', is presented. In the N-M algorithm context, different strategies are proposed to enhance the quality of the solutions and improve the overall efficiency. The main goal of this paper is to use a two-level factorial design of experiments to analyze the statistical significance of the observed differences in selected performance criteria produced when testing different strategies in the N-M based repulsion algorithm. The main goal of this paper is to use a two-level factorial design of experiments to analyze the statistical significance of the observed differences in selected performance criteria produced when testing different strategies in the N-M based repulsion algorithm.

A firefly dynamic penalty approach for solving engineering design problems

Firefly Algorithm is a recent swarm intelligence method, inspired by the social behavior of fireflies, based on their flashing and attraction characteristics [1, 2]. In this paper, we analyze the implementation of a dynamic penalty approach combined with the Firefly algorithm for solving constrained global optimization problems. In order to assess the applicability and performance of the proposed method, some benchmark problems from engineering design optimization are considered.

Sustentabilidade no Design: uma abordagem aos resíduos limpos das indústrias do calçado

Dissertação de mestrado em Design e Marketing

Estudo da influência cultural no Design de Calçado

Dissertação de mestrado em Design e Marketing

Protected environments and substrates for production of genipap seedlings

Genipap (Genipa americana L., Rubiaceae ) is a native Brazilian species and can be used in the recovery of degraded forest areas or for food supply. In order for the species to reach its potential, production of high quality seedlings is essential. The objective of this study was to evaluate genipap seedlings in protected environments and different substrates. The environments tested were: (1) a greenhouse with polyethylene film in the top, with aluminized screen (Aliminet®) of 50%-shading under this film, and lateral sides covered with 50%-shading nylon net (Sombrite®), (2) a shaded hut, all sides covered with 50%-shading nylon net (Sombrite®), and (3) a nursery shelter, with all lateral sides uncovered and the roof covered with leaves of buriti (Mauritia flexuosa). In these environments the following substrates were tested: 50% cattle manure + 50% cassava foliage, 50% cattle manure + 50% Vida Verde®, 50% cattle manure + 50% vermiculite, and 25% cattle manure + 25% vermiculite + 25% of cassava foliage + 25% Vida Verde®. Because there was no repetition of the growth environment, the effect of environment was examined using statistical procedures for analysis of combined experiments. Within environments a completely randomized design was used with five replications. All substrates are suitable for the formation of genipap seedlings, where the recommended substrates are: 50% cattle manure + 50% cassava foliage and 50% cattle manure + 50% Vida Verde® for the greenhouse and the substrates composed of 50% cattle manure + 50% vermiculite and 25% cattle manure + 25% cassava foliage + 25% Vida Verde®+ 25% vermiculite for the shaded hut. The buriti shelter is not recommended for production of genipap seedlings.

Development of a thermoelectric generator for the exhaust of a vehicle

Dissertação de mestrado integrado em Engenharia Mecânica