In scaffold aided regeneration of muscular tissue, composite materials are currently utilized as a temporary substrate to stimulate tissue formation by controlled electrochemical signals as well as ...continuous mechanical stimulation until the regeneration processes are completed. Among them, composites from the blending of conductive (CPs) and biocompatible polymers are powerfully emerging as a successful strategy for the regeneration of myocardium due to their unique conductive and biological recognition properties able to assure a more efficient electroactive stimulation of cells. Here, different composite substrates made of synthesized polyaniline (sPANi) and polycaprolactone (PCL) were investigated as platforms for cardiac tissue regeneration. Preliminary, a comparative analysis of substrates conductivity performed on casted films endowed with synthesized polyaniline (sPANi) short fibres or blended with emeraldine base polyaniline (EBPANi) allows to study the attitude of charge transport, depending on the conducting filler amount, shape and spatial distribution. In particular, conducibility tests indicated that sPANi short fibres provide a more efficient transfer of electric signal due to the spatial organization of electroactive needle-like phases up to form a percolative network. On the basis of this characterization, sPANi/PCL electrospun membranes have been also optimized to mimic either the morphological and functional features of the cardiac muscle ECM. The presence of sPANi does not relevantly affect the fibre architecture as confirmed by SEM/image analysis investigation which shows a broader distribution of fibres with only a slight reduction of the average fibre diameter from 7.1 to 6.4 μm. Meanwhile, biological assays—evaluation of cell survival rate by MTT assay and immunostaining of sarcomeric α-actinin of cardiomyocites-like cells—clearly indicate that conductive signals offered by PANi needles, promote the cardiogenic differentiation of hMSC into cardiomyocite-like cells. These preliminary results concur to promise the development of electroactive biodegradable substrates able to efficiently stimulate the basic cell mechanisms, paving the way towards a new generation of synthetic patches for the support of the regeneration of damaged myocardium.
Protein-based nanomaterials are gaining growing interest in biomedical field. The present paper evaluates the physico-chemical properties of electrospun nanofibers resulting from the combination of ...gelatin with keratin (from wool) and sericin (from silk) to validate their use for in vitro interaction studies. We demonstrated that that presence of sericin influences the fiber morphology at macroscopic level – i.e., wide diameter distributions by SEM and image analysis – with effects on chemical – i.e., a decrease of hydrogen bonds of NH groups verified by infrared spectroscopy – and thermal behavior of electrospun nanofibers, in comparison with gelatin-based ones. Moreover, we verified that sericin, in combination with keratin macromolecules, can amplify the biochemical signal of gelatin, improving the in-vitro stability of gelatin-based nanofibers. In vitro results confirm a synergistic effect of sericin and keratin on human Mesenchymal Stem Cells (hMSC) proliferation – increase over 50% respect to other types – associated to the enhancement of in vitro stability directly ascribable to the peculiar physical interaction among the proteins. These findings suggest the use of sericin/keratin/gelatin enriched electrospun fibers as nanostructured platforms for interface tissue engineering.
•Keratin was extracted from wool by alkali, sericin from silk by boiling water.•Electrospinning of protein blends of gelatin, keratin and sericin was carried out.•Sericin changes morphology, bonding and thermal behavior of gelatin.•Keratin fixes sericin into the fibers enhancing the cell adhesion.•Gelatin, keratin and sericin contribute to cell proliferation in fiber biomaterials.
We review a novel free space optical (FSO) system that represents a significant breakthrough in the area of FSO communications. The system encompasses a pair of novel terminals: these allow direct ...and transparent optical connection to common single mode fibers and include a dedicated electronic control unit that effectively tracks the signal beam wandering due to atmospheric turbulence and mechanical vibrations. Further improvement in the signal power stabilization is achieved by means of saturated EDFAs. These solutions allow to realize a new FSO system, which is tested in a double-pass FSO link between two buildings in Pisa, Italy. When the terminals are fed by common WDM signals they allow enough power budget and margins to support a record high capacity transmission (32times40 Gbit/s), with a enormous improvement of stability (six hours with no error burst). During day-long transmission, the system behavior has been deeply characterized to correlate any increase of bit error ratio (BER) to the FSO control parameters.
In different human carcinoma types, mast cell infiltrate increases with respect to normal tissue and mast cell density correlates with a bad prognosis. To assess the role of mast cells in human ...thyroid cancer, we compared the density of tryptase-positive mast cells in 96 papillary thyroid carcinomas (PTCs) versus normal thyroid tissue from 14 healthy individuals. Mast cell density was higher in 95% of PTCs (n=91) than in control tissue. Mast cell infiltrate correlated with extrathyroidal extension (P=0.0005) of PTCs. We show that thyroid cancer cell-line-derived soluble factors induce mast cell activation and chemoattraction in vitro. Different mast cell lines (HMC-1 and LAD2) and primary human lung mast cells induced thyroid cancer cell invasive ability, survival and DNA synthesis in vitro. The latter effect was mainly mediated by three mast-cell-derived mediators: histamine, and chemokines CXCL1/GROα and CXCL10/IP10. We show that xenografts of thyroid carcinoma cells (8505-C) could recruit mast cells injected into the tail vein of mice. Co-injection of human mast cells accelerated the growth of thyroid cancer cell (8505-C) xenografts in athymic mice. This effect was mediated by increased tumor vascularization and proliferation, and was reverted by treating mice with sodium cromoglycate (Cromolyn), a specific mast cell inhibitor. In conclusion, our study data suggest that mast cells are recruited into thyroid carcinomas and promote proliferation, survival and invasive ability of cancer cells, thereby contributing to thyroid carcinoma growth and invasiveness.
Marine Isotope Stage (MIS) 5e (130–116 ka) represents a “laboratory” for evaluating climate model performance under warmer‐than‐present conditions. Climate model simulations for MIS 5e have ...previously failed to produce Southern Ocean (SO) sea‐surface temperatures (SSTs) and sea‐ice extent reconstructed from marine sediment core proxy records. Here we compare state of the art HadGEM3 and HadCM3 simulations of Peak MIS 5e SO summer SSTs and September sea‐ice concentrations with the latest marine sediment core proxy data. The model outputs and proxy records show the least consistency in the regions located near the present‐day SO gyre boundaries, implying the possibility that model simulations are currently unable to fully realize changes in gyre extent and position during MIS 5e. Including Heinrich 11 meltwater forcing in Peak MIS 5e climate simulations improves the likeness to proxy data but it is clear that longer (3–4 ka) run times are required to fully test the consistency between models and data.
Plain Language Summary
Investigating past warm periods can provide us with an analog for how climate will respond to future warming. In this study we compare the latest model simulations of Southern Ocean (SO) sea‐surface temperatures and Antarctic winter sea‐ice extent from 130,000 years ago with data from marine sediment cores. The simulations and sediment core data show the least match in the areas near the boundaries of the present day SO gyres (large, circulating ocean currents), implying that possibly changes in the position and size of the gyres are not fully recreated in the computer simulations. The inclusion of ice sheet meltwater into the North Atlantic improves the comparison between the simulations and sediment core data but it is clear that longer run times are required to fully test their consistency.
Key Points
Different areas of the Southern Ocean (SO) show different consistency between model simulations and proxy data
Regions along the edges of the modern day SO gyres show the least consistency between models and proxy data
Inclusion of Heinrich 11 meltwater forcing improves the match between model simulations and proxy data
Magnetic field assisted electrospinning is supplemented by conductive sheets that envelop the magnets and have the same potential as the deposition electrode. By optimizing the experimental ...conditions, it is possible to produce wires made of polymer nanofibers that incorporate longitudinally oriented magnetic particles. The morphological and magnetic characterizations confirm the preferential orientations. The new nanofiber wires are easily aligned along the maximum intensity line of the applied magnetic field. Moreover, the nanostructured wires have high longitudinal elastomagnetic strain and high transversal deflection as a response to magnetic field stimuli. Therefore, these new threadlike aggregates of magnetic nanofibers could be very appealing for application in all microelectronic or biomedical devices whose functionality requires orientation or deformation.
In this work, three-dimensional porous composite scaffolds, based on poly(epsilon-caprolactone) (PCL), were fabricated through the combination of a filament winding technique and a phase ...inversion/salt leaching process. Sodium chloride crystals were used as the porogen agent, and poly(lactic acid) (PLA) fibers and calcium phosphates as reinforcement. The aim of the current work is to assess the effective synergistic role of bioactive particles (i.e. alpha-tricalcium phosphates (alpha-TCP)) and PLA fibers on the morphology and mechanical response of the final scaffold. Morphological investigations performed on fiber-reinforced composite scaffolds with different PCL/alpha-TCP volume ratios (0%, 13%, 20% and 26%) show a high porosity degree (ca. 80%), pore interconnection and a homogeneous distribution of pores within the scaffold. More specifically, a bimodal pore size distribution was observed. This comprised microporosity (pores with radii ranging from 0.1 to 10 microm, which were strictly related to solvent extraction) and macroporosity (pores with radii from 10 to 300 microm, which were ascribable to the leaching of porogen elements). Static compressive tests showed that the effect of alpha-TCP on the mechanical response was to increase the elastic modulus up to a maximum value of 2.21+/-0.24 MPa, depending on the concentration of alpha-TCP added. This effect may be explained through the interaction of calcium-deficient hydroxyapatite crystals, formed as a consequence of a hydrolysis reaction of alpha-TCP, and the fiber-reinforced polymer matrix. The correct balance between chemical composition and spatial organization of reinforcement systems allows the attainment of an ideal compromise between mechanical response and bioactive potential, facilitating the development of composite scaffolds for bone tissue engineering applications.
Small polymeric ducts incorporating a ribbon-shaped mat of densely packed magnetic nanofibers have been manufactured via electrospinning by using a cylindrical manifold, alternately under rotation or ...static. The magnetic nanofibers mat is located on the side of the tube and aligned to the longitudinal axis using the assistance of a magnetic field. The designed methodology ensures that the magnetic particles are completely wrapped into a protective polymer shell. Experimental results demonstrate that the innovative confinement of magnetic nanofibers, forming a longitudinal ribbon on a tube side, confers a high and reversible transverse strain under a moderate magnetic field stimulus: a magnetic field gradient <30 mT/mm, at a basic field intensity <0.04 T, induces a 40% decrement of the duct radius aligned with the magnetic force axis. In perspective, this is very attractive to fabricate magneto-active ducts suitable for microfluidic components, as well as biomedical devices to be applied in surgery and endoscopy.
Electrospinning technique has been successfully used to produce composite nanofibers combining magnetic nanoparticles with polymer matrices. Process conditions to assembly nanofibers in tubular ...systems, as well as their morphological and elastomagnetic properties, have been explored. A volume percentage of magnetic charge close to 30% has been achieved. The optimization of the fabrication method ensures that the particles are completely covered by a thin polymer shell, so safe-guarding bio-compatibility. In particular, the deformation induced by the direct elastomagnetic effect, applying a static or a pulsed magnetic field, has been investigated. Resultant devices exhibit good elastomagnetic stretchability at room temperature-longitudinal relative strain/exciting field ~4.10-3/(1.5.104 A/m)-, thus suggesting their potential use for applications in biomedical field as magneto-active components, as well as sensors and actuators.
The accretion-powered X-ray pulsar GX 301−2 was observed with the balloon-borne X-Calibur hard X-ray polarimeter during late 2018 December, with contiguous observations by the Neutron star Interior ...Composition Explorer Mission (NICER) X-ray telescope, the Swift X-ray Telescope and Burst Alert Telescope, and the Fermi Gamma-ray Burst Monitor spanning several months. The observations detected the pulsar in a rare apastron flaring state coinciding with a significant spin up of the pulsar discovered with the Fermi Gamma-ray Burst Monitor. The X-Calibur, NICER, and Swift observations reveal a pulse profile strongly dominated by one main peak, and the NICER and Swift data show strong variation of the profile from pulse to pulse. The X-Calibur observations constrain for the first time the linear polarization of the 15-35 keV emission from a highly magnetized accreting neutron star, indicating a polarization degree of % (90% confidence limit) averaged over all pulse phases. We discuss the spin up and the X-ray spectral and polarimetric results in the context of theoretical predictions. We conclude with a discussion of the scientific potential of future observations of highly magnetized neutron stars with the more sensitive follow-up mission XL-Calibur.
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