Evaluation of commercial implants with nanoindentation defines future development needs for hydroxyapatite coatings

The performance of biomedical implants relies on the ability to assess and refine the microstructure of biomaterials. Instrumented nanoindentation was applied to determine the mechanical properties of plasma sprayed hydroxyapatite-coated implants from different commercial vendors. All biomedical devices contained both amorphous and crystalline phases. Nanoindentation of the amorphous phase revealed a hardness of 1.5 ± 0.3 GPa and an elastic modulus of 48 ± 6 GPa. The crystalline phase revealed a range in hardness of 3.0-7.7 GPa. The large range is attributed to the presence of porosity, surrounding amorphous areas, and hydroxyapatite (unmolten particle cores and recrystallized hydroxyapatite). A selection of the powder type (spray-dried or sintered) leads to different mechanical properties within the coating. A spray-dried powder provides a lower hardness and elastic modulus when unmolten particle cores are included in the coating. Meanwhile recrystallized areas are intermediate in hardness. The combination of a polished cross-section and nanoindentation offers the ability to determine a range of quality control tests including hardness, elastic modulus, bond strength, fracture toughness, substrate and coating roughness, crystallinity, and coating thickness. Property maps determined from nanoindentation will provide a graphical representation of the mechanical property distribution within the coating and provide a basis for coating property refinements. The assessment of commercial coatings is used a basis for discussion of future developments for hydroxyapatite coatings

Product Design of Greater Added Value (PGAV) using urban pruning wood from Curitiba

Este trabalho teve como objetivo aplicar o resíduo de podas de árvores da floresta urbana do município de Curitiba por meio de um projeto de design gerando um Produto de Maior Valor Agregado (PMVA). Utilizou-se de metodologias tradicionais do design e estudos de áreas inter- relacionadas ao tema, possibilitando desenvolver um produto com foco no problema de descarte e subutilização da “madeira de poda urbana”. A construção do protótipo foi possível após realização de muitos testes utilizando e analisando formas e processos de produção e a interação entre os vários materiais estudados. O resultado apresentado como mesa de centro, uma peça híbrida, com mistura dos materiais madeira, ferro e vidro, atingiu seus pré-requisitos de um produto ecologicamente correto, composto por materiais recicláveis e resíduos com alta potencial de utilização. Contudo, teve a amostra da boa utilização do resíduo, agregou valor ao resíduo e ainda pode promover a utilização deste tipo de resíduo em novas atividades econômicas.This work aimed to apply the waste from tree pruning in the urban forest of the city of Curitiba through a design project generating a Product of Greater Added Value (PGAV). Traditional design methodologies and studies of areas interrelated to the theme were used, making it possible to develop a product focused on the problem of discarding and under-utilizing “urban pruning wood”. The construction of the prototype was possible after carrying out many tests using and analyzing forms and production processes and the interaction between the various materials studied. The result presented as a coffee table, a hybrid piece, with a mixture of wood, iron and glass materials, reached its prerequisites for an ecologically correct product, composed of recyclable materials and waste with high potential for use. However, it had a sample of the good use of the waste, added value to the waste and can still promote the use of this type of waste in new economic activities

Micro bubble flow detachment in a model ultrasound contrast agent system

The in-vitro detachment of targeted micro-bubbles in both static and continuous flow conditions was investigated to determine if micro-bubbles can be clinically used as targeted ultrasound contrast agents. Ultrasound contrast agents are micro-bubbles coated in a lipid, protein or polymer shell. On intravenous injection they dramatically enhance blood vessels in ultrasound imaging. Targeted micro-bubbles are now being developed, which would adhere to and thus identify microscopic disease tissues. The present work is based on a novel form of protein shelled micro-bubble whose performance has never been assessed. Reynolds number and shear stress are both thought to affect the detachment of micro-bubbles. In particular the links binding bubbles to their targets can easily be broken by fluid flow forces. Pairs of molecules modelling the link between the bubble and target were selected (BSA, Anti-BSA and Streptavidin, Biotin) based on their affinity for each other and their ease of use. Micro-bubbles were prepared and purified. These bubbles were then attached to Petri dishes that had been prepared with the relevant pair and had been blocked to stop any non-specific binding. These dishes were then placed in a flow cell where shear stresses applicable to in-vivo conditions were applied. Flow rates were varied. Data were captured using a microscope with an attached video camera. The images were then processed to quantify the detachment. Preliminary results show that protein based micro-bubbles can be successfully targeted and suggest that they should remain on target under the shear stresses present in human blood vessels