Search

We report on a new approach toward a laser-assisted modification of biocompatible polydimethylsiloxane (PDMS) elastomers relevant to the fabrication of stretchable multielectrode arrays (MEAs) devices for neural interfacing technologies. These applications require high-density electrode packaging to provide a high-resolution integrating system for neural stimulation and/or recording. Medical grade PDMS elastomers are highly flexible with low Young’s modulus &lt, 1 MPa, which are similar to soft tissue (nerve, brain, muscles) among the other known biopolymers, and can easily adjust to the soft tissue curvatures. This property ensures tight contact between the electrodes and tissue and promotes intensive development of PDMS-based MEAs interfacing devices in the basic neuroscience, neural prosthetics, and hybrid bionic systems, connecting the human nervous system with electronic or robotic prostheses for restoring and treating neurological diseases. By using the UV harmonics 266 and 355 nm of Nd:YAG laser medical grade PDMS elastomer is modified by ns-laser ablation of in water. A new approach of processing is proposed to (i) activate the surface and to obtain tracks with (ii) symmetric U-shaped profiles and (iii) homogeneous microstructure This technology provides miniaturization of the device and successful functionalization by electroless metallization of the tracks with platinum (Pt) without preliminary sensitization by tin (Sn) and chemical activation by palladium (Pd). As a result, platinum black layers with a cauliflower-like structure with low values of sheet resistance between 1 and 8 Ω/sq are obtained.

The objectives of this study were to obtain a complete series of graphene oxide and nano sized zinc oxide and to make a structural and phase characterization of the resulting composites. XRD, SEM, EDX, TEM and impedance analyses were used to investigate these materials as energy storage devices. The complex dielectric permittivity was measured for all samples as a function of frequency. All dielectric characteristics were studied (frequencies from from 100 Hz to 1 MHz and temperatures from 150 to 400 K). The composite GO/ZnO - 80/20 is closer to the desired properties.

Investigations on sodium-ion conducting polymer blend electrolyte systems based on PEO/ PVP, complexed with NaIO4 salt and TiO2 nanofiller, are presented in this report. The complexed polymer blend electrolytes were prepared in the form of dimensionally stable and free-standing films by conventional solution cast technique. Micro Raman and XRD studies confirmed the miscibility between PEO and PVP and the complexation of the salt with PEO/PVP polymer host. TEM measurements were carried out to evaluate size & distribution of the dispersed TiO2 nanofiller. Complex impedance spectroscopy was performed in the 1 Hz – 1 MHz frequency range within the temperature range from room temperature to 343 K. Ionic conductivity of blend electrolytes increased with the increase of TiO2 nanofiller concentration. Electrical conductivity and dielectric properties of NaIO4 salt-complexed blend PEO/PVP/Na+ electrolytes were analyzed as a function of TiO2 nanofiller concentration.

The Sari��i��ek howardite meteorite shower consisting of 343 documented stones occurred on 2 September 2015 in Turkey and is the first documented howardite fall. Cosmogenic isotopes show that Sari��i��ek experienced a complex cosmic ray exposure history, exposed during ~12-14 Ma in a regolith near the surface of a parent asteroid, and that an ca.1 m sized meteoroid was launched by an impact 22 +/- 2 Ma ago to Earth (as did one third of all HED meteorites). SIMS dating of zircon and baddeleyite yielded 4550.4 +/- 2.5 Ma and 4553 +/- 8.8 Ma crystallization ages for the basaltic magma clasts. The apatite U-Pb age of 4525 +/- 17 Ma, K-Ar age of ~3.9 Ga, and the U,Th-He ages of 1.8 +/- 0.7 and 2.6 +/- 0.3 Ga are interpreted to represent thermal metamorphic and impact-related resetting ages, respectively. Petrographic, geochemical and O-, Cr- and Ti- isotopic studies confirm that Sari��i��ek belongs to the normal clan of HED meteorites. Petrographic observations and analysis of organic material indicate a small portion of carbonaceous chondrite material in the Sari��i��ek regolith and organic contamination of the meteorite after a few days on soil. Video observations of the fall show an atmospheric entry at 17.3 +/- 0.8 kms-1 from NW, fragmentations at 37, 33, 31 and 27 km altitude, and provide a pre-atmospheric orbit that is the first dynamical link between the normal HED meteorite clan and the inner Main Belt. Spectral data indicate the similarity of Sari��i��ek with the Vesta asteroid family spectra, a group of asteroids stretching to delivery resonances, which includes (4) Vesta. Dynamical modeling of meteoroid delivery to Earth shows that the disruption of a ca.1 km sized Vesta family asteroid or a ~10 km sized impact crater on Vesta is required to provide sufficient meteoroids

16 figures, 6 tables.-- Supplementary material available., Ceria-iron oxide mesoporous materials with Fe:Ce molar ratio of 5:5 and 9:1 were synthesized by hydrothermal method using CTAB as a template and subsequently modified with NiO (molar ratio Ni:Fe = 1:2) by incipient wetness impregnation technique. In order to increase the electro-capacitive properties and reduce the intrinsic impedance of the metal oxides, the samples were consecutively modified by reduction in hydrogen to obtain highly dispersed Ni–Fe alloys into ceria matrix. By exploiting the high permeability of carbon inside ferrous alloys, the metal phase has been further modified into ferrous carbides and metal alloys encapsulated within carbon nanofibers. For this purpose, a reaction, already widely studied for the production of hydrogen, was used, that is the decomposition of methanol vapors. In fact, this decomposition, in addition to producing syn-gas and methane, changes the catalysts in use through a chemical vapor deposition-carbon coating process. This fact, has been used by us to demonstrate how the newly obtained metal-carbon nanocomposites can be used for electro-catalytic purposes. The modified phases of the two molar ratios of the Fe–Ni–Ce catalysts were tested in the Oxygen Evolution Reaction (OER) in an alkaline environment (1 M KOH), showing a satisfactory and progressive increase in activity and a surprising decrease in the overpotential at 10 mA/cm2 of current density. The morphological, textural and physicochemical properties of the samples were characterized in details by XRD, N2-physisorption, TG-TPO, TEM, EDX, FTIR, XPS, Raman and Moessbauer spectroscopies., This research was funded by the BIKE project, which received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement no. 813748.