In the last decade, population ageing has been registered as a global phenomenon. A relation exists between falling and ageing, since falling frequency increases significantly with age. In fact, one in three older adult falls annually. Although ageing is generically associated with decrease and degeneration of psychological and physical functions, it is still not common for the correct identification of risk factors to lead to a clinical prognosis of the elder being in risk of falling. Therefore, the goal of this review article is to identify, categorise and analyse typical ageing and fall factors mentioned in the literature as well as to quantify the number of times they were referenced. The research considered hundreds of publications, but analysis was then restricted to the 87 most pertinent articles written in English and published in journals or scientific magazines between 1995 and 2010. We concluded that falls among older adults can be characterised by the following: anatomic characteristics and physiological consequences of ageing; the pathologies that induce falls, which can be neurological, musculoskeletal, cardiovascular and other diseases; causes and risk factors of falls that can be behavioural, biological, environmental or socio-economic; type of physical consequences of falls, including fractures, bruises, injuries or other physical consequences; and strategies to prevent, mitigate or rehabilitate, which can be of a physical, environmental or behavioural nature.
Bone is a remarkable tissue that can respond to external stimuli. The importance of mechanical forces on the mass and structural development of bone has long been accepted. This adaptation behaviour is very complex and involves multidisciplinary concepts, and significant progress has recently been made in understanding this process. In this review, we describe the state of the art studies in this area and highlight current insights while simultaneously clarifying some basic yet essential topics related to the origin of mechanical stimulus in bone, the biomechanisms associated with mechanotransduction, the nature of physiological bone stimuli and the test systems most commonly used to study the mechanical stimulation of bone.
This article aims to review the biomechanical evolution of intramedullary nailing and describe the breakthrough concepts which allowed for nail improvement and its current success. The understanding of this field establishes an adequate background for forthcoming research and allows to infer on the path for future developments on intramedullary nailing. It was not until the 1940s, with the revolutionary Küntscher intramedullary nailing design, that this method was recognized as a widespread medical procedure. Such achievement was established based on the foundations created from intuitionbased experiments and the first biomechanical ideologies. The nail evolved from allowing alignment and stability through press-fit fixation with nail-cortical wall friction to the nowadays nail stability achieved through interlocking screws mechanical linkage between nail and bone. Important landmarks during nail evolution comprise the introduction of flexible reaming, the progress from slotted to non-slotted nails design, the introduction of nail 'dynamization' and the use of titanium alloys as a new nail material. Current biomechanical improvement efforts aim to enhance the boneintramedullary nail system stability. We suggested that benefit would be attained from a better understanding of the ideal mechano-biological environment at the fracture site, and future improvements will emerge from combining mechanics and biological tools.
Combining contributions from engineering and medicine, we highlight the biomechanical turning points in the historical evolution of the intramedullary nailing stabilization technique and discuss the recent innovations concerning increase in bone-implant system stability. Following the earliest attempts, where stabilization of long bone fractures was purely based on intuition, intramedullary nailing evolved from allowing alignment and translational control through press-fit fixation to current clinical widespread acceptance marked by the mechanical linkage between nail and bone with interlocking screws that allow alignment, translation, rotation, and length control. In an attempt to achieve an optimum interfragmentary mechanical environment, recent improvements considered the impact of different biomaterials on bone-implant stiffness. Another strategy considered the increase in the structural stability through the reduction of the number of movements between the different components that constitute the bone-implant system. Intramedullary nail improvements will most likely benefit from merging mechanics and fracture-healing biology by combining surface engineering with sensor tools associated with the innovative progress in wireless technology and with bone-healing biological active agents. Future research should aim at better understanding the ideal mechanobiological environment for each stage of fracture healing in order to allow for intramedullary nail design that satisfies such requirements.
Microcapsules produced by interfacial polycondensation of p-phenylenediamine (PPD) and sebacoyl chloride (SC) were studied. The products were characterized in terms of morphology, mean diameter and effectiveness of dodecane encapsulation. The use of Tween 20 as dispersion stabilizer, in comparison with polyvinyl alcohol (PVA), reduced considerably the mean diameter of the microcapsules and originated smoother wall surfaces. When compared to ethylenediamine (EDA), microcapsules produced with PPD monomer were more rigid and brittle, prone to fracture during processing and ineffective retention of the core liquid. The use of diethylenetriamine (DETA) cross-linker in combination with PPD did not decrease capsule fragility. On the other hand, addition of a small fraction of oleic acid to the organic phase remarkably improved wall toughness and lead to successful encapsulation of the core-oil. Oleic acid is believed to act as a plasticizer. Its incorporation in the polymeric wall was demonstrated by FTIR and (1)H-NMR.
Bone is an outstanding, well-designed composite. It is constituted by a multi-level structure wherein its properties and behavior are dependent on its composition and structural organization at different length scales. The combination of unique mechanical properties with adaptive and self-healing abilities makes bone an innovative model for the future design of synthetic biomimetic composites with improved performance in bone repair and regeneration. However, the relation between structure and properties in bone is very complex. In this review article, we intend to describe the hierarchical organization of bone on progressively greater scales and present the basic concepts that are fundamental to understanding the arrangement-based mechanical properties at each length scale and their influence on bone’s overall structural behavior. The need for a better understanding of bone’s intricate composite structure is also highlighted.
Abstract:The functions of proteins in living organisms are related to their 3-D structure, which is known to be ultimately determined by their linear sequence of amino acids that together form these macromolecules. It is, therefore, of great importance to be able to understand and predict how the protein 3D-structure arises from a particular linear sequence of amino acids. In this paper we report the application of Machine Learning methods to predict, with high values of accuracy, the secondary structure of proteins, namely α-helices and β-sheets, which are intermediate levels of the local structure.Keywords: data mining; machine learning; classification; decision trees; rule induction; instance-based learning; Bayesian algorithms; WEKA; bioinformatics; protein folding; predicting secondary structure conformations.Copyright © 2012 Inderscience Enterprises Ltd. 572 R. Camacho et al.Reference to this paper should be made as follows: Camacho, R., Ferreira, R., Rosa, N., Guimarães, V., Fonseca, N.A., Costa, V.S., de Sousa, M. and Magalhães, A. (2012)
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