5 research outputs found
DEVELOPMENT OF A RECYCLABLE NATURAL BASED THERMAL INSULATOR NANOCOMPOSITE
No full textThis work was focused on the development of a fully recyclable thermal and acoustical insulation nanocomposite with improved fire resistance behavior in which Graphene Oxide (GO) was used as flame retardant. The nanocomposite was based on a previously developed alginate-based insulator foam, in which fibre-glass waste is down-cycled by incorporation into the polyanionic gel matrix before lyophilization. The complete functional recycling was carried out by designing a new process capable of disassembling and then rebuilding the ionic matrix – which is initially formed by the interaction between a cation (e.g. calcium) and the negatively charged alginate backbone – with the use of a chelator (Ethylenediaminetetraacetic acid disodium salt, EDTA) easily controlled via pH shift. The effectiveness of the recycling process was primarily assessed through characterization of the functional properties on an optimized version of the alginate composite, at first, and on the GO nanocomposite afterward. Data showed that thermal, acoustical and mechanical properties were maintained or even improved in the recycled samples. A multi parametric life cycle assessment (LCA) study showed that, at the lab scale, the recycling option is preferable to simple material disposal and substitution due to the reduction of the environmental footprint of the recycling process. A second comparative analysis, operated also by defining an industrial scaled version of the recycling process, allowed to identify, in the electric energy consumption and in the EDTA syntheses, the most environmentally critical contributors associated with the recycling process, paving the way to futures developments. Cone calorimetry was used to evaluate the fire resistance effect of the introduction of GO in the nanocomposite: data show major improvements at a concentration of only 2\% with the GO acting with a physical barrier mechanism. In addition both the recycled foam and nanocomposite showed an improved fire resistance behavior respect to their original counterparts primarily ascribed to modifications introduced by the recycling process. Eventually, to improve flame resistance activity of GO and compatibilization with the alginate matrix, different GO functionalization, with polyamines and nano-aluminium hydroxides, were synthesized and fully characterized
An engineering insight into the relationship of selective cytoskeletal impairment and biomechanics of HeLa cells
No full textIt is widely accepted that the pathological state of cells is characterized by a modification of mechanical properties, affecting cellular shape and viscoelasticity as well as adhesion behaviour and motility. Thus, assessing these parameters could represent an interesting tool to monitor disease development and progression, but also the effects of drug treatments. Since biomechanical properties of cells are strongly related to cytoskeletal architecture, in this work we extensively studied the effects of selective impairments of actin microfilaments and microtubules on HeLa cells through force-deformation curves and stress relaxation tests with atomic force microscopy. Confocal microscopy was also used to display the effects of the used drugs on the cytoskeletal structure. In synergy with the aforementioned methods, stress relaxation data were used to assess the storage and loss moduli, as a complementary way to describe the influence of cytoskeletal components on cellular viscoelasticity. Our results indicate that F-actin and microtubules play a complementary role in the cell stiffness and viscoelasticity, and both are fundamental for the adhesion properties. Our data support also the application of biomechanics as a tool to study diseases and their treatments
Carbon Nanotubes, Directly Grown on Supporting Surfaces, Improve Neuronal Activity in Hippocampal Neuronal Networks
No full textCarbon nanotube (CNT)–modified surfaces unequivocally demonstrate their biocompatibility and ability to boost the electrical activity of neuronal cells cultured on them. Reasons for this effect are still under debate. However, the intimate contact at the membrane level between these thready nanostructures and cells, in combination with their unique electrical properties, seems to play an important role. The entire existing literature exploiting the effect of CNTs on modulating cellular behavior deals with cell cultures grown on purified multiwalled carbon nanotubes (MWNTs) deposited on a supporting surface via drop‐casting or mechanical entrapment. Here, for the first time, it is demonstrated that CNTs directly grown on a supporting silicon surface by a chemical vapor deposition (CVD)–assisted technique have the same effect. It is shown that primary neuronal cells developed above a carpet of CVD CNTs form a healthy and functional network. The resulting neuronal network shows increased electrical activity when compared to a similar network developed on a control glass surface. The low cost and high versatility of the here presented CVD‐based synthesis process, together with the possibility to create on supporting substrate patterns of any arbitrary shape of CNTs, open up new opportunities for brain–machine interfaces or neuroprosthetic devices
A contribution of star-forming clumps and accreting satellites to the mass assembly of z ∼ 2 galaxies
No full text\ua9 2019 The Author(s).We investigate the contribution of clumps and satellites to the galaxy mass assembly. We analysed spatially resolved Hubble Space Telescope observations (imaging and slitless spectroscopy) of 53 star-forming galaxies at z ∼ 1-3. We created continuum and emission line maps and pinpointed residual \u27blobs\u27 detected after subtracting the galaxy disc. Those were separated into compact (unresolved) and extended (resolved) components. Extended components have sizes ∼2 kpc and comparable stellar mass and age as the galaxy discs, whereas the compact components are 1.5 dex less massive and 0.4 dex younger than the discs. Furthermore, the extended blobs are typically found at larger distances from the galaxy barycentre than the compact ones. Prompted by these observations and by the comparison with simulations, we suggest that compact blobs are in situ formed clumps, whereas the extended ones are accreting satellites. Clumps and satellites enclose, respectively, ∼20 per cent and 80 per cent of the galaxy stellar mass, ∼30 per cent and ∼20 per cent of its star formation rate. Considering the compact blobs, we statistically estimated that massive clumps (Mθ ≳ 109 Mθ) have lifetimes of ∼650 Myr, and the less massive ones (108 < Mθ < 109 Mθ) of ∼145 Myr. This supports simulations predicting long-lived clumps (lifetime ≳100 Myr). Finally, ≲30 per cent (13 per cent) of our sample galaxies are undergoing single (multiple) merger(s), they have a projected separation≲10 kpc, and the typical mass ratio of our satellites is 1:5 (but ranges between 1:10 and 1:1), in agreement with literature results for close pair galaxies
