ABSTRACT
The increasing attention given to environmental protection, largely through specific regulations on environmental impact and the recycling of materials, has led to a considerable interest of researchers in biocomposites, materials consisting of bio-based or green polymer matrixes reinforced by natural fibers. Among the various reinforcing natural fibers, sisal fibers are particularly promising for their good mechanical properties, low specific weight and wide availability on the current market. As proven in literature by various authors, the hybridization of biocomposites by synthetical fibers or different natural fibers can lead to an interesting improvement of the mechanical properties or, in turn, of the strength against environmental agents. Consequently, this can lead to a significant enlargement of their practical applications, in particular from quite common non-structural applications (dashboards, fillings, soundproofing, etc.) towards semi-structural (panels, etc.) and structural applications (structural elements of civil construction and/or machine components). Hybridizations with natural fibers or with ecofriendly basalt fibers are the most interesting ones, since they permit the improvement of the biocomposite's performance without an appreciable increment on environmental impact, as occurs instead for synthetic fiber hybridizations that are also widely proposed in the literature. In order to further increase the mechanical performance and, above all, to reduce the aging effects on high-performance sisal-reinforced biocomposites due to environmental agents, the hybridization of such biocomposites with basalt fibers are studied with tensile, compression and delamination tests performed by varying the exposition to environmental agents. In brief, the experimental analysis has shown that hybridization can lead to further enhancements of mechanical performance (strength and stiffness) that increase with basalt volume fraction and can lead to appreciable reductions in the aging effects on mechanical performance by simple hybridization of the surface laminae. Therefore, such a hybridization can be advantageously used in all practical outdoor applications in which high-performance sisal biocomposites can be exposed to significant environmental agents (temperature, humidity, UV).
ABSTRACT
Biocomposites are increasingly used in the industry for the replacement of synthetic materials, thanks to their good mechanical properties, being lightweight, and having low cost. Unfortunately, in several potential fields of structural application their static strength and fatigue life are not high enough. For this reason, several chemical treatments on the fibers have been proposed in literature, although still without fully satisfactory results. To overcome this drawback, in this study we present a procedure based on the addition of a carbonaceous filler to a green epoxy matrix reinforced by Agave sisalana fibers. Among all carbon-based materials, biochar was selected for its environmental friendliness, along with its ability to improve the mechanical properties of polymers. Different percentages of biochar, 1, 2, and 4 wt %, were finely dispersed into the resin using a mixer and a sonicator, then a compression molding process coupled with an optimized thermomechanical cure process was used to produce a short fiber biocomposite with Vf = 35%. Systematic experimental tests have shown that the presence of biochar, in the amount 2 wt %, has significant effects on the matrix and fiber interphase, and leads to an increase of up to three orders of magnitude in the fatigue life, together with an appreciable improvement in static tensile strength.
ABSTRACT
The use of natural fiber-based composites is on the rise in many industries. Thanks to their eco-sustainability, these innovative materials make it possible to adapt the production of components, systems and machines to the increasingly stringent regulations on environmental protection, while at the same time reducing production costs, weight and operating costs. Optimizing the mechanical properties of biocomposites is an important goal of applied research. In this work, using a new numerical approach, the effects of the volume fraction, average length, distribution of orientation and curvature of fibers on the Young's modulus of a biocomposite reinforced with short natural fibers were studied. Although the proposed approach could be applied to any biocomposite, sisal fibers and an eco-sustainable thermosetting matrix (green epoxy) were considered in both simulations and the associated experimental assessment. The results of the simulations showed the following effects of the aforementioned parameters on Young's modulus: a linear growth with the volume fraction, nonlinear growth as the length of the fibers increased, a reduction as the average curvature increased and an increase in stiffness in the x-y plane as the distribution of fiber orientation in the z direction decreased.
ABSTRACT
BACKGROUND: In 2015, Italy was the second most common point of entry for asylum seekers into Europe after Greece. The vast majority embarked from war-torn Libya; 80,000 people claimed asylum that year. Their medical conditions were assessed on arrival but their mental health needs were not addressed in any way, despite the likelihood of serious trauma before and during migration. Médecins sans Frontières (MSF), in agreement with the Italian Ministry of Health, provided mental health (MH) assessment and care for recently-landed asylum seekers in Sicily. This study documents mental health conditions, potentially traumatic events and post-migratory living difficulties experienced by asylum seekers in the MSF programme in 2014-15. METHODS: All asylum seekers transiting the 15 MSF-supported centres were invited to a psycho-educational session. A team of psychologists and cultural mediators then provided assessment and care for those identified with MH conditions. Potentially traumatic events experienced before and during the journey, as well as post-migratory living difficulties, were recorded. All those diagnosed with MH conditions from October 2014 to December 2015 were included in the study. RESULTS: Among 385 individuals who presented themselves for a MH screening during the study period, 193 (50%) were identified and diagnosed with MH conditions. Most were young, West African males who had left their home-countries more than a year prior to arrival. The most common MH conditions were post traumatic stress disorder (31%) and depression (20%). Potentially traumatic events were experienced frequently in the home country (60%) and during migration (89%). Being in a combat situation or at risk of death, having witnessed violence or death and having been in detention were the main traumas. Lack of activities, worries about home, loneliness and fear of being sent home were the main difficulties at the AS centres. CONCLUSION: MH conditions, potentially traumatic events and post-migratory living difficulties are commonly experienced by recently-arrived ASs, this study suggests that mental health and psychosocial support and improved living circumstances should be integrated into European medical and social services provided by authorities in order to fulfil their humanitarian responsibility and reduce the burden of assimilation on receiving countries.
ABSTRACT
BACKGROUND: In recent years Europe has received an increasing influx of migrants, many of whom risked their lives crossing the Mediterranean Sea. In October 2013, Italy launched a search and rescue operation at sea in response to migrant deaths during the sea crossing. In August 2014, Médecins sans Frontières and the local Ministry of Health established an outpatient clinic at Augusta harbor, in Sicily, which received 26 % of total sea migrants arrived in Italy in 2014, to provide immediate medical assessment and care. METHODS: This is a descriptive study of demographic and clinical data of sea migrants seen at the port clinic in Augusta from August to December 2014. We compared migrants from Near Eastern, war-torn regions (Group 1) and the others, mostly African (Group 2), as there were significant differences in terms of demographic and morbidity profiles. RESULTS: There were 2593 migrants consulting the clinic (17 % af all rescued migrants) with 5 % being referred to hospital. Most were young males. The overall burden of vulnerability (pregnant women, children ≤5 years, unaccompanied minors, single parents with children of minor age, disabled and elderly persons) was 24 %. There were more small children, pregnant women, elderly, disabled, and persons with chronic diseases in Group 1, as compared to Group 2. Group 2 had more unaccompanied minors. Morbitidies in common were respiratory, dermatological, trauma-related and gastrointestinal conditions. However, acute and chronic cardiovascular disease, as well as diabetes, were more frequent in Group 1; chronic diseases affected 19 % of this group. Group 2 had more patients with skin diseases. Most migrants attributed their presenting symptoms to the perils of their journey. No risks for public health were detected. CONCLUSION: Among sea migrants, we identified two groups with different demographic and clinical characteristics, as well as vulnerability patterns. Overall morbidity suggested that the dangerous journey affected migrants' health. Medical activities at reception sites should include screening for vulnerability and chronic disease management. Ensuring medical care to migrants on arrival can address European humanitarian obligations and provide support to local medical facilities.
