Astronomy & Astrophysics (A&A) is an international journal which publishes papers on all aspects of astronomy and astrophysics

A hitherto unreported postdeposition method of relaxing ultrahigh internal stresses prevailing in sputter-grown thin films is the subject of the present research. A significant reduction of stress has been confirmed by x-ray diffraction and independent substrate deflection measurements for HfN films treated with ${\mathrm{Si}}^{\mathrm{+}}$ ions of various energies (450 keV, 500 keV, and 1.1 MeV). The particular sequence of the performed experiments has allowed us to deduce the most likely scenario of the resulting stress relaxation. We argue that the observed reduction of internal stress had been caused by structural changes, namely the transport of interstitial defects occurring within the thermal spikes induced by ion bombardment and an increase in vacancy concentration. Simple theoretical considerations proved that the existence of an amorphous silicon interlayer formed right under the HfN film during the bombardment cannot be the cause of the observed stress relaxation. The employed Auger electron spectroscopy, transmission electron microscopy, and x-ray diffraction technique confirmed that the ion bombardment did not seriously affect either the composition, dislocation structure, or texture of nitride films. The relative softening of HfN after ion bombardment was found to be caused by amorphization of the substrate directly under the film. The penetration of incident particles deeper than predicted by a numerical simulation was attributed to a distinct crystallographic texture determined experimentally for HfN films. It was confirmed that modification with ${\mathrm{Si}}^{\mathrm{+}}$ ions does not affect the resistivity of HfN films.

Cardiovascular clamping procedures can cause tissue traumatization, leading to serious adverse events interrupting blood flow and causing life-threatening hemorrhage. The aim of the study is to evaluate the properties of 3D-printed, high-elasticity elastomeric materials—BioMed Flex 50A and 80A (Formlabs Inc., Sommerville, MA, USA)—in terms of their suitability for the fabrication of atraumatic inserts used for surgical clamping instruments. To show the importance of the elaboration of the new atraumatic materials, finite element simulations of blood vessel compression by a surgical tool were validated experimentally with porcine vessels, and histopathology assessed the tissue response. These results confirm that excessive clamping forces can cause vessel wall stratification and rupture. Specimens BioMed Flex 50A and 80A underwent surface, mechanical, and biological testing, including topography, wettability, acoustic microscopy for structural voids, cytotoxicity with human dermal fibroblasts, pro-inflammatory marker analysis, and bacterial biofilm assessment. The results of the testing of the 3D-printed BioMed Flex 50A and 80A materials show good potential for applications in safe atraumatic surgical instruments. Further research may include the possibilities to develop 3D-printed metamaterials with pressure adapting properties.

Nowadays, biosensor technology development is directed toward improvement of sensing devices' biocompatibility. Polyelectrolyte multilayer films (PEMs) consisting of natural polymers seem to be appropriate for electrode coverage and localization of semiconducting nanoparticles in order to create controllable polymer–nanoparticles tridimensional networks. However, control of nanoparticles' release from films and in a consequence their cytotoxicity is still a challenge. In this study we demonstrated that the cytotoxic effect of silicon carbide (SiC) nanoparticles introduced by the plasma activated chemical vapor deposition (PACVD) method into poly-L-lysine/hyaluronic acid (PLL/HA) or poly-L-lysine/alginate acid (PLL/ALG) films could be controlled by chemical cross-linking of the polyelectrolyte film. Herein, we tested two types of cross-linkers N-hydrosulfosuccinimide/1-ethyl-3-(3-dimethylamino-propyl)carbodiimide (NHS/EDC) and genipin reagent. Analysis of nanoparticle distribution by scanning electron microscopy (SEM) has shown conglomerate formation in each film type. High resolution transmission electron microscopy (HRTEM) images indicated a cubic structure of SiC and localization of nanoparticles in the polymer coating. Among the tested cross-linkers, either NHS/EDC or genipin seem to be suitable for control of nanocomposite properties due to low cytotoxicity and an effective stabilization of the polymer–nanoparticle interaction, resulting in a lower release rate of nanoparticles from the films.