RESUMO
By assimilating shape memory alloys with mathematical multifractal-type objects, a theoretical model based on Scale Relativity Theory in the form of The Multifractal Theory of Motion, in order to explain the mechanical behavior of such material, is proposed. The model is validated by analyzing the mechanical behavior of Cu-Al-Zn shape memory alloy with various chemical compositions. More precisely, the multifractal tunnel effect can "mime" the mechanical hysteresis of such a material, a situation in which a direct correspondence for several mechanical properties of Cu-Al-Zn is highlighted (the chemical composition can be correlated with the shapes of the curves controlled through the multifractality degree, while the areas delimited by the same curves can be correlated with the multifractal specific potential, as a measure of the mechanical memory degree).
RESUMO
In vitro electrochemical characterization and in vivo implantation in an animal model were employed to evaluate the degradation behaviour and the biological activity of FeMnSi and FeMnSiCa alloys obtained using UltraCast (Ar atmosphere) melting. Electrochemical characterization was based on open circuit potential measurement, electrochemical impedance spectroscopy and potentiodynamic polarization techniques while the alloys were immersed in Ringer's solution at 37⯰C for 7â¯days. Higher corrosion rates were measured for the Ca-containing material, resulting from inefficient passivation of the metal surface by oxy-hydroxide products. In vivo osseointegration was investigated on a tibia implant model in rabbits by referring to a standard control (AISI 316â¯L) stainless steel using standard biochemical, histological and radiological methods of investigation. Changes in the biochemical parameters were related to the main stages of the bone defect repair, whereas implantation of the alloys in rabbit's tibia provided the necessary mechanical support to the injured bone area and facilitated the growth of the newly connective tissue, as well as osteoid formation and mineralization, as revealed by either histological sections or computed tomography reconstructed images and validated by the bone morphometric indices. The present study highlighted that the FeMnSiCa alloy promotes better osteoinduction and osseconduction processes when compared to the base FeMnSi alloy or with AISI 316â¯L, and in vivo degradation rates correlate well with corrosion resistance measurements in Ringer's solution.
Assuntos
Ligas , Materiais Biocompatíveis , Ligas/farmacologia , Animais , Materiais Biocompatíveis/farmacologia , Corrosão , Teste de Materiais , Osseointegração , Próteses e Implantes , CoelhosRESUMO
Evidence suggests that older driver safety may be improved by good vehicle maintenance, in-vehicle advanced technologies, and proper vehicle adaptations. This study explored the prevalence of several measures of vehicle maintenance and damage among older drivers through inspection of their vehicles. We also investigated the prevalence of in-vehicle technologies and aftermarket adaptations. Vehicle inspections were conducted by trained research staff using an objective, standardized procedure. This procedure, developed by a multidisciplinary team of researchers, was based on a review of inspection checklists used by automobile dealerships and the project team's expertise. The study used baseline data from vehicles of 2988 participants in the multi-site Longitudinal Research on Aging Drivers (LongROAD) study. Among this cohort, vehicles were well maintained, had little damage, and contained a range of advanced technologies but few aftermarket adaptations. Implications of study findings for occupational therapy practice are discussed.
Assuntos
Acidentes de Trânsito/prevenção & controle , Condução de Veículo , Automóveis , Segurança , Tecnologia Assistiva , Tecnologia , Fatores Etários , Idoso , Estudos de Coortes , Feminino , Humanos , Masculino , Terapia OcupacionalRESUMO
The purpose of the present study was to gain a better understanding of the types of in-vehicle technologies being used by older drivers as well as older drivers' use, learning, and perceptions of safety related to these technologies among a large cohort of older drivers at multiple sites in the United States. A secondary purpose was to explore the prevalence of aftermarket vehicle adaptations and how older adults go about making adaptations and how they learn to use them. The study utilized baseline questionnaire data from 2990 participants from the Longitudinal Research on Aging Drivers (LongROAD) study. Fifteen in-vehicle technologies and 12 aftermarket vehicle adaptations were investigated. Overall, 57.2% of participants had at least one advanced technology in their primary vehicle. The number of technologies in a vehicle was significantly related to being male, having a higher income, and having a higher education level. The majority of respondents learned to use these technologies on their own, with "figured-it-out-myself" being reported by 25%-75% of respondents across the technologies. Overall, technologies were always used about 43% of the time, with wide variability among the technologies. Across all technologies, nearly 70% of respondents who had these technologies believed that they made them a safer driver. With regard to vehicle adaptations, less than 9% of respondents had at least one vehicle adaptation present, with the number of adaptations per vehicle ranging from 0 to 4.â¯A large majority did not work with a professional to make or learn about the aftermarket vehicle adaptation.
Assuntos
Acidentes de Trânsito , Condução de Veículo , Conhecimentos, Atitudes e Prática em Saúde , Aprendizagem , Veículos Automotores , Segurança , Tecnologia , Fatores Etários , Idoso , Atitude , Estudos de Coortes , Feminino , Humanos , Masculino , Percepção , Prevalência , Fatores Socioeconômicos , Inquéritos e Questionários , Estados UnidosRESUMO
Advanced in-vehicle technologies have been proposed as a potential way to keep older adults driving for as long as they can safely do so, by taking into account the common declines in functional abilities experienced by older adults. The purpose of this report was to synthesize the knowledge about older drivers and advanced in-vehicle technologies, focusing on three areas: use (how older drivers use these technologies), perception (what they think about the technologies), and outcomes (the safety and/or comfort benefits of the technologies). Twelve technologies were selected for review and grouped into three categories: crash avoidance systems (lane departure warning, curve speed warning, forward collision warning, blind spot warning, parking assistance); in-vehicle information systems (navigation assistance, intelligent speed adaptation); and other systems (adaptive cruise control, automatic crash notification, night vision enhancement, adaptive headlight, voice activated control). A comprehensive and systematic search was conducted for each technology to collect related publications. 271 articles were included into the final review. Research findings for each of the 12 technologies are synthesized in relation to how older adults use and think about the technologies as well as potential benefits. These results are presented separately for each technology. Can advanced in-vehicle technologies help extend the period over which an older adult can drive safely? This report answers this question with an optimistic "yes." Some of the technologies reviewed in this report have been shown to help older drivers avoid crashes, improve the ease and comfort of driving, and travel to places and at times that they might normally avoid.