Applied Mechanics and Materials Vol. 890

Abstract: The aim of the present review was to highlight some of the available processes for cartilage repair and regeneration. Considering the high impact that cartilage degeneration has in the quality of life, in an aging society, efforts to promote better treatments are crucial. The current available processes have advantages and drawbacks, that should be further investigated, aiming to obtain tailored and successful repair. Finally, some suggestions for tissue engineering strategies are presented, so that the scientific community can debate pros and cons to be investigated.

Abstract: This review describes available smart biomaterials for biomedical applications. Biomaterials have gained special attention because of their characteristics, along with biocompatibility, biodegradability, renewability, and inexpensiveness. In addition, they are also sensitive towards various stimuli such as temperature, light, magnetic, electro, pH and can respond to two or more stimuli at the same time. In this manuscript, the suitability of stimuli-responsive smart polymers was examined, providing examples of its usefulness in the biomedical applications.

Abstract: In recent years, sheep have been reported as the ideal animal model to study osteoporosis, hence it is important to identify instruments, tools and ideal parameters needed to assess the effects of different treatments. In previous studies conducted in other animal models with osteoporosis, the most common parameters used for evaluation concerned primarily bone properties, such as the dual X-ray absorptiometry. However, biomechanical gait analysis as an integrative functional parameter and a non-invasive method, will be an important tool in research and clinical applications. This research review was performed using the PubMed database and included studies related to sheep with outcome measures concerning functional performance assessed during gait in vivo; and excluded studies related with cardiovascular disease and sperm properties, which include other animal species, with outcomes not related with functional locomotor evaluation. Only studies related with bone properties were analyzed. The most frequent and relevant included parameters were the following: mean peak vertical ground force reaction, gait cycle and stance/swing phase duration, percentage of stance/swing phase in a gait cycle, stride length and the stifle joint angles during a gait cycle. Gait biomechanical parameters have been established for the assessment of some clinical orthopedic condition using sheep models but not currently for osteoporosis.

Abstract: With increasing competition between companies, they are increasingly striving to produce higher quality products and to improve their production processes, and the food industry is no different. In order to preserve food for longer, this type of company has dedicated its attention to intelligent packaging, capable of preserving food for longer and of acting as a sensor of the state of food. To develop a film capable of fulfilling the new ambitions of the companies various manufacturing processes have been studied. This document gives an overview of the electrospinning process, capable of producing nanofibres of biological materials. This document aims to serve as a study base for the I.film project through the study of the process that will provide the polymer film with the necessary biological characteristics.

Abstract: Cartilage related diseases are on the top list concerns of the World Health Organization, being the prevention of articular cartilage degeneration a major health matter for which there are few effective solutions. Using an extrusion-based approach and a polyester elastomer it was aimed to produce 3D structures with controlled architecture and with closer mimicry to cartilage native tissue. The obtained constructs demonstrated high reliability, being the addition of poly (glycerol sebacate) a procedure to enhance the properties of the constructs.

Abstract: This pilot study aims to define a protocol for optimizing the micro-computed tomography (micro-CT) settings to evaluate in the future research the root canal filling in oval shaped canals. Thirty distal canals of mandibular molars were used. After preparation of the canals, the roots were randomly divided into five groups. The canals were filled with two types of sealers (Endosequence BC Sealer or AH Plus) and two types of gutta percha (Protaper Next cones and Endosequence BC cones), using thermal obturation in comparison with a single cone obturation technique. Each specimen was scanned three times using a micro-CT device at a resolution of 30,1 μm. The first scan was done for selecting the specimen according the inclusion criteria, the second one post-instrumentation and the last micro-CT scan after obturation the specimens. For the present study, the images were only evaluated with qualitative criteria and the settings for acquisition, reconstruction and analysis of micro-CT images were tested.

Abstract: To produce multi-material scaffolds for Tissue Engineering accurate techniques are needed in order to obtain three-dimensional constructs with clinically appropriate size and structural integrity. This paper presents a novel biomanufacturing system that can fabricate 3D scaffolds with precise shape and porosity which is achieved through the control of all fabrication modules by an integrated computational platform. The incorporation of a clean flow unit and a camera allows to obtain scaffolds in a clean environment and provides a monitoring tool to analyse constructs during the production, respectively. In this research work is demonstrated that the new system enables the fabrication of multi-material 3D structures using poly (e-caprolactone) and sodium alginate for potential use in Tissue Engineering applications.

Abstract: Tissue Engineering depends on broadly techniques to regenerate tissues and/or organ functions. To do so, tailored polymeric and/or hydrogel scaffolds may be used to ensure the appropriate regeneration. Hydrogels are suitable materials for constructing cell-laden matrices as they can be produced with incorporation of cells and rapidly cross-linked in situ through photopolymerisation reactions. Measurement of the polymerization degree, as well as resistance to compression and water retention are fundamental tests to evaluate the characteristics of hydrogels. In this work, free-radical polymerisation of poly (ethylene glycol)-dimethacrylate (PEGDMA) in UV light was assessed. Several hydrogels with different photoinitiator and water contents were produced to evaluate their influence on hydrogels behaviour. Experiments showed that variations on water and photoinitiator content induce changes in the physical and chemical behaviour of hydrogels. As it was found, water content prevents polymerisation to occur and reduces the mechanical properties of hydrogels weakening them. Furthermore, differences were found in varying water content from 15 to 30%, since this increase turned hydrogels more fragile and increase their stabilization time for water retention.

Abstract: Gait in children with cerebral palsy (CP) is often affected by motor impairments which limit the patient's ability to walk. To improve gait and reduce walking limitations, children with CP need to use ankle foot orthoses. An orthosis is an externally applied device that is designed and fitted to the body to achieve one or more of the following goals: a) Control biomechanical alignment. b) Correct or accommodate deformity, and 3) Protect and support an injury. This systematic review aims to describe research evidence supporting the use of ankle-foot orthoses to improve gait biomechanical outcomes among individuals with CP. Literature search was pursued from PubMed database. Studies were included if (1) they evaluated an outcome measure related with gait using ankle-foot orthotic (AFO) in children (2) considered children with a diagnosis of CP and have a (3) GMFCS classification of I, II or III. Papers were excluded if they evaluated (1) other population besides CP, (2) the use of orthoses other than AFOs and (3) gait analysis procedure was not presented. All the included studies have analyzed spatiotemporal parameters, the step length (m), stride length (m) and cadence (steps/minute) were the most frequently reported. Our findings showed that several studies have investigated the effects of AFOs, all of which have reported positive influences on at least one gait parameter, as well as positive changes in joint kinematics and kinetic in children with CP.

Abstract: We review here the current research status on bioreactors for tissue engineering with cell electrical stimulation. Depending on the cell types, electrical stimulation has distinct objectives, in particular being employed both to mimic and enhance the endogenous electricity measured in the natural regeneration of living organisms as well as to mimic strain working conditions for contractible tissues (for instance muscle and cardiac tissues). Understanding the distinct parameters involved in electrical stimulation is crucial to optimize its application. The results presented in the literature and reviewed here reveal that the application of electrical stimulation can be essential for tissue engineering applications.