12,758 research outputs found
Potential use of split-beam echosounder angular information for bivalve banks cartography: a critical evaluation
Peer Reviewe
Lithium-ion batteries towards circular economy: A literature review of opportunities and issues of recycling treatments
Nowadays, Lithium-ion batteries are widely used in advanced technological devices and Electric and Hybrid Vehicles, due to their high energy density for weight, reduced memory effect and significant number of supported charging/discharging cycles. As a consequence, the production and the use of Lithium-ion batteries will continuously increase in the near future, focusing the global attention on their End-of-Life management. Unfortunately, wasted Lithium-ion batteries treatments are still under development, far from the optimization of recycling processes and technologies, and currently recycling represents the only alternative for the social, economic and environmental sustainability of this market, able to minimize toxicity of End-of-Life products, to create a monetary gain and to lead to the independence from foreign resources or critical materials. This paper analyses the current alternatives for the recycling of Lithium-ion batteries, specifically focusing on available procedures for batteries securing and discharging, mechanical pre-treatments and materials recovery processes (i.e. pyro- and hydrometallurgical), and it highlights the pros and cons of treatments in terms of energy consumption, recovery efficiency and safety issues. Target metals (e.g. Cobalt, Nickel and Lithium) are listed and prioritized, and the economic advantage deriving by the material recovery is outlined. An in-depth literature review was conducted, analysing the existing industrial processes, to show the on-going technological solutions proposed by research projects and industrial developments, comparing best results and open issues and criticalities
Glass transition of semi-crystalline PLLA with different morphologies as studied by dynamic mechanical analysis
Poly(L-lactic acid) was crystallized from the
glassy state at different temperatures to produce fully
transformed semi-crystalline specimens exhibiting different
lamellar morphologies. The materials were tested by
dynamic mechanical analysis, where a Tg decrease was
found with an increasing crystallization temperature. Considering
a three-phase model, this tendency was related to
the corresponding increase in the thickness of the rigid
amorphous phase. It is suggested that this phase could, in
some extent, accommodate through local translational/
rotational motions the cooperative motions taking place
within the mobile amorphous phase. This could be due to
the non-compact structure of the cooperatively rearranging
regions, which can present a string-like or fractal structure
in their edges. The width of the loss factor peak associated
to the glass transition increases with increasing crystallization
temperature, suggesting an increase in the broadness of
the distribution of relaxation times. The drop in the storage
modulus across Tg varies systematically with the crystallization
temperature in the different materials and could be
correlated with the crystalline content. Above Tg, the loss
factor exhibits a plateau-like behaviour at significantly high
values, which seems to be a rather general behaviour in
semi-crystalline systems that could be related to the
contribution of pure irreversible flow in the overall
viscoelastic behaviour
In vitro monitoring of surface mechanical properties of poly(L-lactic acid) using microhardness
Poly(L-lactic acid) (PLLA) was immersed in
a simulated body fluid (SBF) solution at 37.58C for distinct
times. The variation of the surface mechanical properties
of PLLA samples with immersion time was followed by
microhardness. These measurements showed that PLLA
microhardness decreased significantly ( 60%) after only
30 days of immersion. The results were explained in terms
of hydrolytic degradation of the samples. The dependence
of microhardness with the applied dwell time was also analyzed.
The creep curves were successfully described by a
power law. A decrease of the creep constant k as the
immersion time increased was found. Differential scanning
calorimetry was also used to analyze the changes in the
physical properties of PLLA, namely in crystallinity degree
(Xc) and glass transition temperature (Tg), as a function of
the immersion time in SBF. A significant variation in the
crystallinity degree of PLLA, initially nearly amorphous
(Xc 5 9%), was detected after only 3 days of immersion
(Xc 5 37%). The interpretation of this behavior was based
on the hydrolysis process suffered by PLLA
Microhardness of starch based biomaterials in simulated physiological conditions
In this work the variation of the surface mechanical properties of starch-based biomaterials with immersion time was followed using
microhardness measurements. Two blends with very distinct water uptake capabilities, starch/cellulose acetate (SCA) and starch/poly-
(e-caprolactone) (SPCL), were immersed in a phosphate buffer solution (PBS) at 37.5 C for various times. The microhardness of the
blends decreased significantly ( 50% for SPCL and 94% for SCA), within a time period of 30 days of immersion, reflecting the different
hydrophilic character of the synthetic components of the blends. The dependence of microhardness on the applied loading time and load
was also analysed and showed a power law dependency for SCA. Water uptake and weight loss measurements were performed for the
same immersion times used in the microhardness experiments. The different swelling/degradation behaviour presented by the blends was
related to the respective variation in microhardness. Moreover, complementary characterization of the mechanical properties of SCA
and SPCL was accomplished by dynamic mechanical analysis (DMA) and creep measurements. Microhardness measurements proved
to be a useful technique for characterizing the mechanical behaviour near the surface of polymeric biomaterials, including in simulated
physiological conditions
Comparative study of the environmental footprints of marinas on European Islands
Ports have been key elements in Europe's economic development. This situation is even more relevant on islands, which are highly dependent on the maritime sector. Consequently, over the years, ports with diverse functionalities have been established both in mainland Europe and on its outlying islands. This article discusses the environmental impact of leisure marinas on European islands, especially as they are closely linked to economic development through tourism. The aim is to study the environmental impact of these infrastructures by determining the carbon and water footprints of marinas on European islands in the Atlantic and the Mediterranean. The results obtained enable the authors to make recommendations in order to reduce the overall environmental footprint of marinas on islands, considering that these territories are much more vulnerable to climate change than mainland locations in Europe
Functional diversification of teleost Fads2 fatty acyl desaturases occurs independently of the trophic level
The long-chain (â„C20) polyunsaturated fatty acid biosynthesis capacity of fish varies among species, with trophic level hypothesised as a major factor. The biosynthesis capacity is largely dependent upon the presence of functionally diversified fatty acyl desaturase 2 (Fads2) enzymes, since many teleosts have lost the gene encoding a Î5 desaturase (Fads1). The present study aimed to characterise Fads2 from four teleosts occupying different trophic levels, namely Sarpa salpa, Chelon labrosus, Pegusa lascaris and Atherina presbyter, which were selected based on available data on functions of Fads2 from closely related species. Therefore, we had insight into the variability of Fads2 within the same phylogenetic group. Our results showed that Fads2 from S. salpa and C. labrosus were both Î6 desaturases with further Î8 activity while P. lascaris and A. presbyter Fads2 showed Î4 activity. Fads2 activities of herbivorous S. salpa are consistent with those reported for carnivorous Sparidae species. The results suggested that trophic level might not directly drive diversification of teleost Fads2 as initially hypothesised, and other factors such as the speciesâ phylogeny appeared to be more influential. In agreement, Fads2 activities from P. lascaris and A. presbyter were similar to their corresponding phylogenetic counterparts Solea senegalensis and Chirostoma estor
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