RESUMO
Alloys for orthopaedic and dentistry applications require high mechanical strength and a low Young's modulus to avoid stress shielding. Metastable ß titanium alloys appear to fulfil these requirements. This study investigated the correlation of phases precipitated in a Ti-12Mo-13Nb alloy with changes in hardness and the Young's modulus. The alloy was produced by arc melting under an argon atmosphere, after which, it was heat treated and cold forged. Two different routes of heat treatment were employed. Phase transformations were studied by employing X-ray diffraction and transmission electron microscopy. Property characterisation was based on Vickers microhardness tests and Young's modulus measurements. The highest ratio of microhardness to the Young's modulus was obtained using thermomechanical treatment, which consists of heating at 1000°C for 24h, water quenching, cold forging to reduce 80% of the area, and ageing at 500°C for 24h, where the final microstructure consisted of an α phase dispersed in a ß matrix. The α phase appeared in two different forms: as fine lamellas (with 240±100 nm length) and massive particles of 200-500 nm size.
Assuntos
Ligas/química , Molibdênio/química , Nióbio/química , Titânio/química , Módulo de Elasticidade , Temperatura Alta , Transição de FaseRESUMO
Inductively coupled plasma optical emission spectrometry (ICP-OES) was applied to the analysis of major and minor elements of Ni-Nb alloys obtained by aluminothermic reduction process. Digestion of samples was made using a mixture of HF+HNO(3). Minor and trace elements were determined without matrix separation. The precision for all constituents was <3%. Recoveries for the analyte-spiked samples were 95%.
RESUMO
O avanço tecnológico produz continuamente equipamentos que podem ser fontes potenciais de interferências eletromagnéticas para os marcapassos cardíacos artificiais implantáveis. O principal objetivo deste trabalho é fornecer esclarecimentos aos profissionais que atuam na área de estimulação cardíaca artificial sobre o potencial de interferência dos telefones celulares analógicos e digitais sobre os marcapassos cardíacos, para que o paciente portador de marcapasso cardíaco implantável seja orientado de forma adequada quanto à sua utilização
Assuntos
Marca-Passo Artificial , Telefone , Segurança de EquipamentosRESUMO
Para o tratamento de pacientes com surdez profunda neurossensorial é indicado o implante coclear, dispositivo eletrônico constituído por uma unidade receptora implantável, uma unidade transmissora e um processador de voz. A função do implante coclear é transformar o sinal sonoro em sinal elétrico que vai até as terminações nervosas ligadas a cóclea. Até a presente data, o implante coclear foi implantado em 3 pacientes, dois dos quais encontram-se em fase final de reabilitação e o terceiro em fase inicial. Os resultados preliminares demonstram a viabilidade de se utilizar um implante monocanal para auxílio a pessoas com surdez profunda.
Abstract - The use of cochlear implants as an aid to patients with neurosensory deafness is an established procedure. Basically is transforms acoustic energy waveforms into electrical signals that stimulate the cochlea through electrodes. ln this paper we present a cochlear implant which consists of a receptor unit. transmitter and speech processor. This device was implanted in three patients. The results obtained until now showed that the use single-channel cochlear implant results in significant beneficial effects
