Search

Electrospun scaffolds exhibiting high physical performances with the ability to support cell attachment and proliferation are attracting more and more scientific interest for tissue engineering applications. The inclusion of inorganic nanoparticles such as nanosilica and nanoclay into electrospun biopolymeric matrices can meet these challenging requirements. The silica and clay incorporation into polymeric nanofibers has been reported to enhance and improve the mechanical properties as well as the osteogenic properties of the scaffolds. In this work, for the first time, the physical and biological properties of polylactic acid (PLA) electrospun mats filled with different concentrations of nanosilica and nanoclay were evaluated and compared. The inclusion of the particles was evaluated through morphological investigations and Fourier transform infrared spectroscopy. The morphology of nanofibers was differently affected by the amount and kind of fillers and it was correlated to the viscosity of the polymeric suspensions. The wettability of the scaffolds, evaluated through wet contact angle measurements, slightly increased for both the nanocomposites. The crystallinity of the systems was investigated by differential scanning calorimetry highlighting the nucleating action of both nanosilica and nanoclay on PLA. Scaffolds were mechanically characterized with tensile tests to evaluate the reinforcing action of the fillers. Finally, cell culture assays with pre‐osteoblastic cells were conducted on a selected composite scaffold in order to compare the cell proliferation and morphology with that of neat PLA scaffolds. Based on the results, we can convince that nanosilica and nanoclay can be both considered great potential fillers for electrospun systems engineered for bone tissue regeneration.

Introduction Electrospinning is a versatile process technology for the production of fibers ranging from nano- to micro-scale. In order to develop high performance electrospun systems, the use of nanofillers is achieving more and more interest. In this context, silica (Si) and clays (Cl) are often used as fillers due to the possibility to combine the advantages of polymeric materials, such as light weight and flexibility, and inorganic materials, such as high mechanical strength, heat stability, and chemical stability. In this work, the morphology of PLA/Si and PLA/Cl were evaluated on two different weight ratios: 99/1 and 95/5 wt/wt. Material and Methods The nanoparticles were added to a solution of TCM/Ac (2:1 volume). PLA (10 wt% with respect to the solvent phase) was then added to the mixture and completely dissolved by continuous magnetic stirring. Nanofibrous mats were produced with a filler mass ratio equal to 1% and 5%. The nanofibers were collected on a grounded rotary drum rotating at 10 rpm. The morphology of the materials was studied by using a Scanning Electron Microscope (SEM). Results SEM images revealed that PLA showed the typical morphology of an electrospun material with smooth and homogenous fibers in the nearly-nanoscale and randomly oriented. Fillers added at 1 wt% are well dispersed in the polymer matrix. Si caused a slight increase and Cl a slight reduction of the fiber diameter. PLA/Si 5 wt% fibers are characterized by a worst particles’ distribution and higher fiber diameters if compared with PLA/Cl 5 wt%. Discussion The different dispersion degree observed at high filler concentration can be likely ascribed to the different affinity of the nanoparticles with both the polymer matrix and the solvent systems. The different fiber diameter can be ascribed to the viscosity of the polymeric solution. Silica induced an increment of the viscosity and a consequent increase of the fiber diameter. The lower fiber diameter observed for PLA/Cl nanocomposites can be ascribed to the reduction of the viscosity probably due to a degradation of PLA, as already observed in other works.

The elongational flow is a very important flow involved in important processing operations, like spinning, film blowing, etc. In these processing operations, the molten polymer is subject to the elongational flow and at the same time is cooled (non-isothermal elongational flow). The response to the non-isothermal elongational flow of the melt is then the critical parameter to process the polymer in these processing operations. MS (melt strength) and BSR (breaking stretching ratio) are to two values measured during the non-isothermal flow and depend mainly on the molecular structure of the polymer. In biphasic systems, the adhesion and the shape of the dispersed particles play a very important role in determining the behaviour of the melt under this flow. Polymer nanocomposites are biphasic systems where the rigid dispersed particles are of nanometric size and this size and the adhesion with the matrix are of relevant importance when these systems are subjected to the non-isothermal elongational flow. In this communication, the non-isothermal elongational flow behaviour of some polymer nanocomposites systems is reported and the effects of the elongational flow on the morphology of polymer nanocomposites are described. The change of the morphology of some of these systems (organoclay modified and graphene nanocomposites) subjected to elongational flow is somehow similar to that already reported for polymer blends. In particular, reduction of the dimensions, exfoliation and alignment along the flow direction have been observed.

Marine pollution has been increasing as a consequence of human activities. In the near future will start the extraction of minerals from ocean depths, Deep Sea Mining (DSM). However, the impacts at the ecosystem level are still unknown. It is necessary to know the effects to contribute to the creation of rules, laws and mining codes that protect and conserve ecosystems and biodiversity. Sea urchin and mussels represents one of the most important seafood product, but also, a sentinel organism for ecotoxicological studies to assess aquatic environments quality. They are directly exposed to anthropogenic contaminants in their habitat. The aim of this study is to understand the influences of two trace element (which will probably be released into the water column by DSM) at three different environmentally realistic concentrations in Arbacia lixula and Mytilus galloprovincialis: Cu (0.6μg/l; 339.15 μg/l; 1709 μg/l), and Pb (1.0 μg/l; 619.16 μg/l; 2291 μg/l). We observed the short-term (3 and 7 days) effects at biochemical level (total cells count, cell mortality, total protein concentration and lysosomal membrane stability) and their bioaccumulation in different tissues. In A. lixula the bioaccumulation was studied in gonads while in M. galloprovincialis in gills and mantle. This study demonstrates the importance of biomonitoring contaminants and understanding how biomarkers relate to each other on exposure to particular contaminants in different species due to their wide application in environmental management. Few studies have used multiple biomarkers in more than a single species to learn about the variability of the sub-lethal effects of a contaminant

Nanobiocomposites are a new class of biodegradable polymer materials with nanometric dispersion of inert particles in a biodegradable polymer matrix that show very interesting properties often very different from those of conventional- filled polymers and also biodegradability. An important issue in the applications of the biodegradable polymers is their easy degradability during processing due to the thermomechanical stress or to the presence of humidity. In this work, the thermomechanical degradation behavior of a nanobiocomposite made by a PLA-based blend and an organomodified montmorillonite has been investigated. The degradation kinetics has been followed by means of rheological, mechanical and morphological characterization. In particular, the influence of temperature and of the presence of humidity have been considered. The presence of the nanoparticles slightly increases the thermomechanical degradation of the pure matrix and in particular with increasing time and temperature processing. In the more severe conditions, indeed, the organomodifier undergoes some slight decomposition of the organomodifier of the clay because of the Hoffmann elimination. The radicals formed through this decomposition enhance the degradation of the matrix. However, this decomposition is at the first stage, and the evolved CO2remains entrapped in the clay increasing the level of intercalation and causing also some exfoliation. Then the morphology of the nanobiocomposite changes because of the processing conditions. Moreover, the thermomechanical degradation remarkably increased if the materials are not pre-dried because of the hydrolytic degradation of the biodegradable polyesters of the matrix.

The creep response of Polymer systems is typically investigated upon applying different loads, or under different temperature. However, no evidence exist of creep studies under different loads and temperatures and the simultaneos actionof accelerated weathering. In a previous paper La Mantia et al. [1] presented a new equipment that is able to subject polymer samples to creep under different loads, but also monitor the effect of photooxidation due to the temperature, humidity and UV irradiation, thus fully simulating the real operating conditions for polymer-based items. In tihs work a polyethylene/organomodified caly nanocompositehas been subjectedto combined creep-accelerated weathering conditions.

The present work develops non-destructive measurements of chemical-physical parameters of concrete, in order to evaluate the degradation condition and to monitor, in time, the aging process. This study in particular focuses on the measurement of parameters such as pH, and therefore the carbonatation level of the concrete, and salt concentration (i.e. chlorides), and the evolution of these quantities with time. The analysis can be extended to other chemical-physical parameter of interests for which is provided a specific microsensor.

In this work the morphology and the rheological and mechanical properties of a nanocomposite made of a polypropylene with graphene nanoplatelets (GNP) have been investigated as a function of the compounding parameters to evaluate the thermomechanical degradation behaviour of this system. The presence of graphene seems to reduce the thermomechanical degradation of the matrix. A better dispersion of the GNP seems the cause of this behaviour.

Compact discs (CDs) and digital versatile discs (DVDs) are mainly made by polycarbonate disc, a thin layer of aluminum or silver, a thin layer of a coating and a thin layer of a label of paper or PET. The recycling of these discs is difficult due to the removal of these non-polymeric layers and to our best knowledge, no industrial plants have been resent for their recycling. In this work, we propose a facile way to remove the non-polymeric layers and investigate the effect of the repetitive extrusion process on the processability and on the mechanical properties of the recycled polycarbonate. A few works have been published dealing with both the removal of the non-polymeric layers and the mechanical recycling of the disk of polycarbonate. In our approach, the removal of the non-polymeric layers is easily obtained through a thermo-mechanical treatment in a basic solution by ammonia. This process can be considered green because is made at a low temperature with a small amount of water and a very small amount of ammonia, saving energy and water. The properties of the polycarbonate remain good if the mechanical recycling is made after drying the post-consumer polycarbonate.

Sound is the most effective means of communication in marine and freshwater ecosystems. However, no data about acoustic emissions from non-malacostracan crustaceans are currently available, so their ability to produce sounds is unknown. For the first time, this study investigated the sound produced by 2 tadpole shrimp species,Triops cancriformisandLepidurus lubbocki.L. lubbockiindividuals were collected from a natural temporary pond in Sicily (Italy), whereasT. cancriformisindividuals were obtained from eggs contained in sediment from a rock pool in Sardinia (Italy). In the laboratory, experimental tanks with the animals (one species at a time) were acoustically monitored. Both species produced high-frequency, wideband pulses distinguishable by their sound pressure level, which was higher inL. lubbocki(146 dB) than inT. cancriformis(130 dB), and by their first and second peak frequencies, which were higher inL. lubbocki(65 and 86 kHz) than inT. cancriformis(63 and 71 kHz). The energy distributions in the power density spectra showed different shapes, as revealed by the 3 dB bandwidth and centre frequency. The pulse durations were 88 and 97 µs inL. lubbockiandT. cancriformis, respectively.L. lubbockipresented a higher emission rate thanT. cancriformisand a marked circadian pattern, with a higher abundance of sounds during the night. This study reports the first evidence of sound emissions from non-malacostracan crustaceans and reveals the high potential of passive acoustic monitoring to detect the presence, abundance, and life cycle of these elusive keystone species of temporary water bodies.