Potential of Graphene–Polymer composites for ligament and tendon repair: a review

Tendon/ligament injuries are debilitating conditions that affect the life quality of a great percentage of the adult population. Several challenges still have to be addressed regarding the repair of these tissues, as current treatments show limited success. The use of biocompatible and biodegradable polymeric scaffolds potentially helps accomplish a complete and long-term functional repair but, unfortunately, these materials lack adequate mechanical properties to be used in such demanding applications. Graphene is a subject of interest for tissue-repair applications due to its electrical conductivity and mechanical properties. If incorporated adequately, it may significantly improve the physical properties of the composite, even at small loadings. Furthermore, graphene presents a biocompatible surface that may enhance cell adhesion, proliferation and differentiation and demonstrates promising outcomes in several in vitro and in vivo biological applications. Therefore, herein, the potential of graphene materials for the reinforcement of biodegradable polymers of interest for tendon/ligament repair is explored. The effect of graphene on relevant features such as mechanical properties, biodegradability, and biocompatibility is revised, to understand the feasibility of these composites to fulfill the requirements associated with these tissues and conclude how their applicability is extended to this field.Portuguese Foundation for Science and Technology (FCT) through the National Funds References UIDB/05256/2020 e UIDP/05256/2020. REQUIMTE-LAQV acknowledges the support of the Portuguese Foundation for Science and Technology (FCT) through the National Funds Reference UIDB/50006/2020. Tânia Peixoto also acknowledges the financial support from FCT, through the PhD Grant PD/BD/143035/201

Sheep Nocturnal Activity Dataset

Monitoring sheep’s behavior is of paramount importance, because deviations from normal patterns may indicate nutritional, thermal or social stress, changes in reproductive status, health issues, or predator attacks. The night period, despite being a more restful period in which animals are theoretically sleeping and resting, represents approximately half of the life cycle of animals; therefore, its study is of immense interest. Wearable sensors have become a widely recognized technique for monitoring activity, both for their precision and the ease with which the sensorized data can be analyzed. The present dataset consists of data from the sensorization of 18 Serra da Estrela sheep, during the nocturnal period between 18 November 2021 and 16 February 2022. The data contain measurements taken by ultrasound and accelerometry of the height from neck to ground, as well as measurements taken by an accelerometer in the monitoring collar. Data were collected every 10 s when the animals were in the shelter. With the collection of data from various sensors, active and inactive periods can be identified throughout the night, quantifying the number and average time of those periods.info:eu-repo/semantics/publishedVersio

Goat Kidding Dataset

The detection of kidding in production animals is of the utmost importance, given the frequency of problems associated with the process, and the fact that timely human help can be a safeguard for the well-being of the mother and kid. The continuous human monitoring of the process is expensive, given the uncertainty of when it will occur, so the establishment of an autonomous mechanism that does so would allow calling the human responsible who could intervene at the opportune moment. The present dataset consists of data from the sensorization of 16 pregnant and two non-pregnant Charnequeira goats, during a period of four weeks, the kidding period. The data include measurements from neck to floor height, measured by ultrasound and accelerometry data measured by an accelerometer existing at the monitoring collar. Data was continuously sampled throughout the experiment every 10 s. The goats were monitored both in the goat shelter (day and night) and during the grazing period in the pasture. The births of the animals were also registered, both in terms of the time at which they took place, but also with details regarding how they took place and the number of offspring, and notes were also added.info:eu-repo/semantics/publishedVersio

Preliminary Analysis of Slope Instability Processes Triggered in the Guilherme Creek Watershed (Nordeste Municipality, S. Miguel Island, Azores)

The Nordeste Volcanic Complex is located in the NE sector of S. Miguel Island (Azores) and it is composed of geological formations with about 4 million years old, extremely weathered. This fact, allied to the steep slopes on the area, promotes the occurrence of slope instability phenomena. In particular, the Guilherme Creek watershed has a high recurrence of this type of geological hazard, mainly triggered by precipitation, which promotes a high density of landslides in the area. Considering as main objective the landslide susceptibility analysis in the Guilherme Creek watershed, using statistical/probabilistic methods, it is ongoing an inventory process of these phenomena in a GIS, based on the aerial photography interpretation and fieldwork. Currently, the inventory is concluded based on aerial photography from 1982 and orthorectified aerial photography from 1995 to 2005. In order to validate and update the landslide inventory produced in the office, fieldwork has been carried out using, besides more traditional techniques, a drone (DJI Phatom 4 PRO). This tool has allowed studying steep slopes, which would otherwise be impossible to access in an area with a high forest density and very steep slopes. Until now, 517 landslides have been identified in the study area, mainly belonging to slides and falls typologies.GeoBioTe

Cohesive mixed-mode damage model applied to the simulation of the mechanical behaviour of a repaired sandwich beam

The behaviour of a repaired sandwich beam loaded under four point bending is simulated using theABAQUS® software. Both overlap and scarf repair, suitable for sandwich structures, were simulatedconsidering two dimensional nonlinear material and geometrical analysis. Special developed interfacefinite elements including a trapezoidal cohesive mixed-mode damage model appropriate for ductileadhesives were used in order to simulate the adhesive layer. The proposed model is intended to replacethe continuum finite elements traditionally used to simulate the adhesive layer, thus reducing thecomputational effort necessary to obtain results. Double Cantilever Beam (DCB) and End NotchedFlexure (ENF) tests were used to obtain the cohesive laws of the adhesive in pure modes I and II,respectively. The fracture energies (JIc and JIIc) are obtained using a new data reduction scheme based oncrack equivalent concept allowing overcoming crack monitoring difficulties during propagation in thesefracture characterization tests. The remaining cohesive parameters (1,I, 1,II, 2,I, 2,II)are obtained usingan inverse method, which is based on the fitting of the numerical and experimental P- curves by a finetuning process. This procedure allows fixing the referred cohesive parameters to be used in the stressanalyses and strength predictions of repaired sandwiches. The numerical model allowed the simulation ofdamage initiation and growth. Geometric changes, such as patch overlap length and scarf angle wereconsidered in the analysis in order to assess their influence on the repair efficiency. Conclusions weredrawn about design guidelines of sandwich composite material repair

Online Monitoring of Composite Overwrapped Pressure Vessels (COPV)

Composite overwrapped pressure vessels (COPV) have been increasingly pointed to as the most effective solution for high pressure storage of liquid and gaseous fluids. Reasonably high stiffness-to-weight ratios make them suitable for both static and mobile applications. However, higher operating pressures are sought continuously, to get higher energy densities in such storage systems, and safety aspects become critical. Thus, reliable design and test procedures are required to reduce the risks of undesired and unpredicted failures. An in-service health monitoring system may contribute to a better product development, design and optimization, as well as to minimize the risks and improve the public acceptance. Within the scope of developing different COPV models for a wide range of operating pressures and applications, optical fiber Bragg grating (FBG) sensors were embedded in the liner-composite and composite-composite interfaces during their manufacturing processes. The idea is to allow the online strain monitoring during preliminary testing and service-life. The ability of these measuring systems to effectively assess the strain fields has been investigated. Simultaneously, a finite element analysis (FEA) was made using the ABAQUS® platform. In this numerical analysis, accurate and realistic simulation of the different materials, geometry and loading conditions was approached. Particularly, the anisotropic nature of the wound laminate and the varying orientation of the fibers were attained. However, the cohesive zones were not attributed independent properties. Comparison between experimental and numerical data was addressed. In general, although the experimental-numerical data agreement was not as good as desired, a preliminary insight to both the structural health monitoring (SHM) system and the numerical modeling approaches was actually achieved. Full characterization and validation shall be further addressed in the continuation of the present work