Анализ причин возникновения врожденных пороков сердца у новорожденных по данным ВДОКБ

ПОРОКИ СЕРДЦА ВРОЖДЕННЫЕСЕРДЕЧНО-СОСУДИСТЫЕ АНОМАЛИИСЕРДЦА БОЛЕЗНИНОВОРОЖДЕННЫЙ, БОЛЕЗН

Molybdenum-based hard nitrides

Zusammenfassung in deutscher SpracheMolybdenum-based cubic-structured nitrides are fascinating materials, predicted by empirical criteria (e.g. valence electron concentration, elastic constants G/B and C12-C44, ionic potential) and proved experimentally as self-lubricating hard coatings with improved toughness. The application area is restricted, however, to lower temperatures, since the weak chemical non-metal-metal bonds tend to break at 300-500 °C and, if exposed to an oxygen-containing atmosphere, the volatile MoO3 can form. Cubic-structured molybdenum nitride is also difficult to synthesise due to its high sensitivity to the nitrogen content present. Hence, to the nitrogen partial pressure used during physical vapour deposition. The cubic-structured of the molybdenum nitride is the high-temperature allotropy of the tetragonal-structured ß-phase. The use of non-equilibrium synthesising techniques such as magnetron sputtering allows, however, the deposition of metastable phases. The distinctive feature of the cubic c-MoNx, as compared to the majority of B1-structured transition metal nitrides, is the highly defected nitrogen sublattice, being 50% vacant. The experimental results, supported by ab initio calculations, suggest that increasing vacancy content at the nitrogen sublattice leads to the formation of coherent domains with high Mo-content (where the interstitial sites are vacant), while decreasing vacancy content at the nitrogen sublattice leads to the formation of coherent domains with partially ordered pseudo-cubic c'-Mo3N2 (actually c'-MoN0.67, where 1/3 of the nitrogen sublattice is vacant). The slightly overstoichiometric c-MoN0.53 (as revealed by elastic recoil detection analysis) was found to exhibit the highest indentation hardness ~33 GPa, which decreases to 28 GPa, when the vacancy content is reduced and partially ordered pseudo-cubic c'-MoN0.67 developed. To extend the temperature range and further improve the properties of c-MoNx-based materials, ternary Mo-Cr-N and Mo-Al-N alloys were developed. Both elements, chromium and aluminium, are well known to significantly improve the oxidation resistance through the formation of dense oxide scales Al2O3 or Cr2O3, preventing or significantly reduce further metal (e.g., Mo) outward and oxygen inward diffusion. For the ternary Mo-Cr-N coatings, the nitrogen partial pressure used during magnetron sputtering is crucial to allow the synthesis of single-phase cubic-structured solid solutions along the entire Mo-Cr composition. For a narrow nitrogen partial pressure window, the solid solution follows the MoN0.5-CrN quasi-binary tie line and, thus, forms a continuous cubic-structured solid solution. The chemical formula along this tie line can be described with Mo1-xCrxN0.5(1+x), indicating that for every vacancy at the nitrogen sublattice that is populated with nitrogen, we need to substitute two Mo-ions with Cr-ions at the metal sublattice. However, high nitrogen partial pressures during deposition favour the formation of fully occupied for combining the cubic structure and high Al content. As soon as the hexagonal phase forms, for too high nitrogen partial pressures or Al contents, the hardness drastically decreases to ~22 GPa. The knowledge gained during the investigation and development of the binary MoNy and the ternaries Mo1-xCrxNy and Mo1-xAlxNy, allowed the development of quaternary Al-rich (x = 0.5 or even 0.6 depending on the Cr-content) single-phase cubic-structured fcc-Mo1-x-yAlxCryNz coatings with hardnesses above 40 GPa. Particularly, fcc-Mo0.39Al0.52Cr0.09N0.98 exhibits the highest hardness, H, of ~41 GPa among all coatings studied. The combination with a relatively low indentation modulus, E, allows for low H/E- and H3/E2-ratios (0.1 and 0.35, respectively). These empirical criteria, related with the elastic strain to failure and resistance to the plastic deformation, respectively, suggest for excellent wear protection and a high potential for severe applications. Summarizing, the combining of experimental and computational materials science provides deeper insights into the complex nature of the substoichiometric nitrides (nitrogen/metal-ratio 0.53) führt zu einer partiellen Ordnung im Stickstoffuntergitter und zur Bildung von kohärenten Domänen der weitgehend unerforschten pseudokubischenc'-MoNx-Phase. Die ab initio berechnete Bildungsenergie von c'-MoNx deutet darauf hin, dass c'-MoNx einen sehr engen Existenzbereich hat (sozusagen eine Strichphase ist) und als c'-MoN0.67 betrachtet werden kann (demnach eine 3:2 Stöchiometrie besitzt). Zwar ist die resultierende Stöchiometrie in beiden Fällen dieselbe (3:2), allerdings bildet sich c'-MoN0.67 ausschließlich mit Leerstellen am Stickstoffuntergitter (mit ~33% Leerstellen, die geordnet sind) und nicht mit Leerstellen in beiden Untergittern (mit jeweils 25% und 50% Leerstellen im Metall- und Stickstoffuntergitter, Mo3N2), wie ursprünglich vermutet. Beim Legieren von c-MoN0.5 mit MeN (Me = Cr, Al) erfolgt die Entwicklung der Elementzusammensetzung im Einklang mit dem quasibinären und Mo-Al-N Systemen ermöglichte die Entwicklung von einphasigen kubisch flächenzentrierten quaternären Mo-Al-Cr-N-Schichten. Auch hier unterliegt die Besetzung der Stickstoffleerstellen der Abhängigkeit entlang der quasibinären Schnitte MoN0.5-MeN, d.h. fcc-Mo1-x-yAlxCryN0.5(1+x+y). Die maximale Al-Löslichkeit, x, in fcc-Mo1-x-yAlxCryNz, variiert (je nach Cr-Gehalt) zwischen 0.5 und 0.6. B. Die maßgeschneiderten mechanischen Eigenschaften Basierend auf den Dichtefunktionaltheorie Berechnungen und den experimentellen Ergebnissen lässt sich schließen, dass der maximale Al-Gehalt in kubischen c-MoNx-basierenden Schichten des Mo-Al-Cr-N-Stoffsystems mit einer maximal möglichen Konzentration an Stickstoffleerstellen einhergeht. Die mechanischen Eigenschaften von Mo1-x-yAlxCryN0.5(1+x+y) Schichten, wie z.B. Härte, H, erreichen ein Maximum wenn die Schichten einphasig kubisch kristallisieren, und neben einem maximalen Al-Gehalt auch geringe Mengen an Chrom enthalten. Die höchsten Härtewerte der binären, ternären und quaternären Schichten wurden mit 33 GPa für c-MoN0.53, 34 GPa für fcc-Mo0.81Cr0.19N0.52, 38 GPa für fcc-Mo0.43Al0.57N0.80 und 41 GPa für fcc-Mo0.39Al0.52Cr0.09N0.98 erreicht. Die Kombination mit moderaten Elastizitätsmoduli, E, erlaubt auch ausgezeichnete H/E- oder H3/E2-Kriterien, die unseren c-MoNx-basierenden Schichten ausgezeichnete Bruchzähigkeit und tribologische Eigenschaften attestieren, die sie für viele anspruchsvolle Anwendungsbereiche auszeichnen.10

Composition driven phase evolution and mechanical properties of Mo-Cr-N hard coatings

Although many research activities concentrate on transition metal nitrides, due to their excellent properties, only little is known about Mo-N based materials. We investigate in detail the influence of Cr on the structural evolution and mechanical properties of Mo-N coatings prepared at different nitrogen partial pressures. The chemical composition as well as the structural development of coatings prepared with N-2-to-total pressure ratios (p(N2)/p(T)) of 0.32 and 0.44 can best be described by the quasi-binary Mo2N-CrN tie line. Mo2N and CrN are face centered cubic (fcc), only that for Mo2N half of the N-sublattice is vacant. Consequently, with increasing Cr content, also the N-sublattice becomes less vacant and the chemical composition of fcc single-phase ternaries can be described as Mo1-xCrxN0.5(1+x). These coatings exhibit an excellent agreement between experimentally and ab initio obtained lattice parameters of fcc Mo1-xCrxN0.5(1+x). When increasing the N-2-to-total pressure ratio to pN(2)/p(T) = 0.69, the N-sublattice is already fully occupied for Cr-additions of x >= 0.4, as suggested by elastic recoil detection analysis and lattice parameter variations. The latter follows the ab initio obtained lattice parameters along the quasi-binary MoN-CrN tie line for x >= 0.5. The single-phase fcc coating with Cr/(Mo+Cr) of x similar to 0.2, prepared with pN(2)/p(T) = 0.32, exhibits the highest hardness of similar to 34 GPa among all coatings studied. (C) 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License

Deformation and Cracking Mechanism in CrN/TiN Multilayer Coatings

In this study, the effects of the microstructural properties on the deformation and damage mechanism of CrN/TiN multilayer coatings deposited on Custom 450 steel using the unbalanced reactive magnetron sputtering PVD process were studied. All coatings were fabricated with an overall thickness of 1.5 µm, but different bilayer periods (Λ). Structural and mechanical properties of coatings were investigated by XRD analysis and nanoindentation experiment, respectively. Indentation tests at three loads of 100, 300, and 450 mN were performed on the coatings’ surface and then, cross-sections of fractured imprints were analyzed with SEM and TEM. Measuring the length of the cracks induced by indentation loads and analyzing the load-displacement curves, apparent fracture energy values of multilayer coatings were calculated. We observed that multilayer systems with bilayer periods of 4.5–15 nm possess superlattice structure, which also results in higher values for Young’s modulus and hardness as well as higher fracture energy. Comparison of cross-sectional SEM and TEM observations showed that coatings with smaller bilayer periods tend to deform by shear sliding mechanism due to the existence of the long-grown columns, while short dispersed grains—growing in the coatings with a larger bilayer period—led to deformation via local grain boundary sliding and grain rotation

Resist-Free E-beam Lithography for Patterning Nanoscale Thick Films on Flexible Substrates

Resist-based lithographic tools, such as electron beam (e-beam) and photolithography, drive today’s state-of-the-art nanoscale fabrication. However, the multistep nature of these processes, expensive resists, and multiple other consumables limit their potential for cost-effective nanotechnology. Here, we report a one-step, resist-free, and scalable methodology for directly structuring thin metallic films on flexible polymeric substrates via e-beam patterning. Controlling e-beam dose results in nanostructures as small as 5 nm in height with a sub-micrometer lateral resolution. We structure nanoscale thick films (100 nm) of Al, TiN, and Au on standard Kapton tape to highlight the universal use of our nanopatterning methodology. Further, we utilize direct e-beam writing to create various high-resolution biomimetic surfaces directly onto ceramic thin films. In addition, we assemble architectured mechanical metamaterials comprising crack “traps”, which confine cracks and prevent overall material/device failure. Such a resist-free lithographic tool can reduce fabrication cost dramatically and may be used for different applications varying from biomimetic and architectured metamaterials to strain-resilient flexible electronics and wearable devices

Microstructure and materials properties of understoichiometric TiB\u3csub\u3ex\u3c/sub\u3e thin films grown by HiPIMS

© 2020 The Authors TiBx thin films with a B content of 1.43 ≤ x ≤ 2.70 were synthesized using high-power impulse magnetron sputtering (HiPIMS) and direct-current magnetron sputtering (DCMS). HiPIMS allows compositions ranging from understoichiometric to overstoichiometric dense TiBx thin films with a B/Ti ratio between 1.43 and 2.06, while DCMS yields overstoichiometric TiBx films with a B/Ti ratio ranging from 2.20 to 2.70. Excess B in overstoichiometric TiBx thin films from DCMS results in a hardness up to 37.7 ± 0.8 GPa, attributed to the formation of an amorphous B-rich tissue phase interlacing stoichiometric TiB2 columnar structures. We furthermore show that understoichiometric TiB1.43 thin films synthesized by HiPIMS, where the deficiency of B is found to be accommodated by Ti-rich planar defects, exhibit a superior hardness of 43.9 ± 0.9 GPa. The apparent fracture toughness and thermal conductivity of understoichiometric TiB1.43 HiPIMS films are 4.2 ± 0.1 MPa√m and 2.46 ± 0.22 W/(m·K), respectively, as compared to corresponding values for overstoichiometric TiB2.70 DCMS film samples of 3.1 ± 0.1 MPa√m and 4.52 ± 0.45 W/(m·K). This work increases the fundamental understanding of understoichiometric TiBx thin films and their materials properties, and shows that understoichiometric films have properties matching or going beyond those with excess B

Unlocking the Potential of CuAgZr Metallic Glasses: A Comprehensive Exploration with Combinatorial Synthesis, High‐Throughput Characterization, and Machine Learning

Abstract In this work, the CuAgZr metallic glasses (MGs) are investigated, a promising material for biomedical applications due to their high strength, corrosion resistance, and antibacterial activity. Using an integrated approach of combinatorial synthesis, high‐throughput characterization, and machine learning (ML), the mechanical properties of CuAgZr MGs are efficiently explored. The investigation find that post‐deposition oxidation in inter‐columnar regions with looser packing causes high oxygen content in Cu‐rich regions, significantly affecting the alloys' mechanical behavior. The study also reveals that nanoscale structural features greatly impact plastic yielding and flow in the alloys. ML algorithms are tested, and the multi‐layer perceptron algorithm produced satisfactory predictions for the alloys' hardness of untested alloys, providing valuable clues for future research. The work demonstrates the potential of using combinatorial synthesis, high‐throughput characterization, and ML  techniques to facilitate the development of new MGs with improved strength and economic feasibility