Influence of surface modification of nitinol with silicon using plasma-immersion ion implantation on the alloy corrosion resistance in artificial physiological solutions

Cyclic voltammetry and potentiostatic polarization have been applied to study electrochemical behavior and to determine corrosion resistance of nitinol, which surface was modified with silicon using plasma-immersion ion implantation, in 0.9% NaCl solution and in artificial blood plasma. It was found out that continuous, and also homogeneous in composition, thin Si-containing layers are resistant to corrosion damage at high positive potentials in artificial physiological solutions due to formation of stable passive films. Breakdown potential Eb of Si-modified NiTi depends on the character of silicon and Ni distribution at the alloy surface, Eb values amounted to 0.9–1.5 V (Ag/AgCl/KCl sat.) for the alloy samples with continuous Si-containing surface layers and with decreased Ni surface concentration

Conformal symmetry in quasi-free Markovian open quantum systems

Conformal symmetry governs the behavior of closed systems near second-order phase transitions, and is expected to emerge in open systems going through dissipative phase transitions. We propose a framework allowing for a manifest description of conformal symmetry in open Markovian systems. The key difference from the closed case is that both conformal algebra and the algebra of local fields are realized on the space of superoperators. We illustrate the framework by a series of examples featuring systems with quadratic Hamiltonians and linear jump operators, where the Liouvillian dynamics can be efficiently analyzed using the formalism of third quantization. We expect that our framework can be extended to interacting systems using an appropriate generalization of the conformal bootstrap.Comment: 15 pages, supplementary Wolfram Mathematica notebook available at https://github.com/idnm/third_quantization v2: minor revision (references added, typos corrected) v2: Minor revisions done and typos correcte

Nonequilibrium structural condition in the medical TiNi-based alloy surface layer treated by electron beam

The research is devoted to study the structural condition and their evolution from the surface to the depth of TiNi specimens treated by low-energy high-current electron beams with surface melting at a beam energy density E = 10 J/cm2, number of pulses N = 10, and pulse duration [tau] = 50 Ps. Determined thickness of the remelted layer, found that it has a layered structure in which each layer differs in phase composition and structural phase state. Refinement B2 phase lattice parameters in local areas showed the presence of strong inhomogeneous lattice strain

Structural phase states in nickel-titanium surface layers doped with silicon by plasma immersion ion implantation

The paper reports on a study of NiTi-based alloys used for manufacturing self-expanding intravascular stents to elucidate how the technological modes of plasma immersion ion implantation with silicon influence the chemical an

Plasma immersion ion implantation for surface treatment of complex branched structures

The paper presents experimental results demonstrating the capabilities of plasma immersion ion implantation of silicon (Si) for surface treatment of complex branched structures such are self-expanding intravascular nickel-titanium (NiTi) stents. Using NiTi stents of diameter 4 and 8 mm, it is shown that plasma immersion ion implantation can provide rather homogeneous doping of their outer and inner surfaces with Si atoms. Also presented are research data on the processes that determine the thickness, composition, and structure of surface layers subjected to this type of treatment

ОСНОВНЫЕ НАПРАВЛЕНИЯ МОДИФИКАЦИИ ПОВЕРХНОСТИ МЕТАЛЛИЧЕСКИХ ЭНДОВАСКУЛЯРНЫХ СТЕНТОВ В РЕШЕНИИ ПРОБЛЕМЫ РЕСТЕНОЗОВ (ОБЗОР, 2 ЧАСТЬ)

Here we review the modifications of the metal stents to enhance in situ endothelialization, particularly antibody-mediated adhesion of endothelial progenitor cells. We focus on the strategies employing cell adhesion molecules and extracellular matrix proteins. We also encompass other physical and chemical approaches for surface biofunctionalization with their advantages and shortcomings.Вторая часть обзора посвящена вариантам модификации металлических стентов для ускорения эндотелизации in situ. Представлены разработки. направленные на захват эндотелиальных прогениторных клеток из кровотока с помощью специфических антител. Описаны возможности улучшения адгезии и интеграции эндотелиальных клеток на поверхности за счет формирования сайтов клеточного распознавания и имитация структур внеклеточного матрикса. Проанализированы различные способы физической и химической модификации, способствующие созданию условий для скорейшего формирования функционально состоятельного эндотелиального слоя на искусственных поверхностях. Определен круг проблем и ограничений в использовании каждого из методов

ОСНОВНЫЕ НАПРАВЛЕНИЯ МОДИФИКАЦИИ ПОВЕРХНОСТИ МЕТАЛЛИЧЕСКИХ ЭНДОВАСКУЛЯРНЫХ СТЕНТОВ В РЕШЕНИИ ПРОБЛЕМЫ РЕСТЕНОЗОВ (ОБЗОР 1 ЧАСТЬ

The therapeutic e[cacy of bare-metal stents is signiVcantly limited due to frequent restenosis. Here we review the approaches for surface modiVcation to prevent restenosis, presented the advantages and disadvantages of each method. In the Vrst part of the review, we consider antithrombotic and antiproliferative stents coating. The review presents the most signiVcant and interesting research aimed forming endothelial layer on the stents surface in vitro.Рестенозы металлических стентов, возникающие после имплантации, остаются нерешенной проблемой и  существенно ограничивают их терапевтическую эффективность. В обзоре освещены наиболее перспективные с точки зрения физиологии и клеточной биологии варианты модификации металлических поверхностей, представлены преимущества и недостатки каждого из методов. В первую часть обзора включены направления, касающиеся разработки стентов с антитромботическим и антипролиферативным покрытием, так же представлены наиболее значимые и интересные исследования, направленные на формирование на поверхности стентов эндотелиального слоя in vitro