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

Low-temperature barrier discharge plasma modification of scaffolds based on polylactic acid

We have explored the effect of low-temperature barrier discharge plasma treatment in oxygen, nitrogen, and argon on modification of the physicochemical properties of polylactic acid (PLA)-based scaffolds. The cellular-mediated immune response to the interaction of macrophages of three donors with the modified surface of PLA-based scaffolds was also nvestigated. Carbonization of the PLA surface accompanied by a carbon atomic concentration increase is shown to occur following plasma treatment. Argon plasma significantly affects the wettability characteristics of PLA; the hydrophilicity and lipophilicity are improved, and the surface energy is increased. The viability of cells in the presence of plasma-modified PLA scaffolds is lower than that for unmodified PLA but remains greater than that for the negative control. We find that PLA scaffolds do not cause increased expression of the proinflammatory (TNFα, IL-6, IL-1β) cytokines after 6 days of cell cultivation. At the same time, PLA scaffolds do not affect the increased production of anti-inflammatory cytokines (IL-10)

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

Oxidative Conversion of Gaseous Alkanes C₃-C₄ in the Barrier Discharge Plasma

Исследована окислительная конверсия газообразных алканов С3-С4 в плазме барьерного разряда в ценные оксигенаты. Процесс протекает в одну стадию без использования катализаторов и при температуре окружающей среды. Основными продуктами окисления являются гидроксильные и карбонильные соединения с тем же числом атомов углерода в молекуле, что и в исходных соединениях, в отличие от процессов парциального окисления пропана и бутанов, где преимущественно образуются метанол, ацетальдегид, формальдегид, низшие карбоновые кислоты и оксиды углерода. Высокая селективность окисления обеспечивается подавлением процесса образования отложений на поверхности электродов реактора добавкой жидкого н-октана к потоку углеводородных газов. Рассмотрен механизм плазмохимического окисления газообразных алканов. Инициирование реакции включает в себя диссоциацию молекул кислорода и алкана под действием электронов разряда. Окисление углеводородных газов протекает по схожему с жидкими алканами механизму. В обоих случаях образование гидроксильных и карбонильных соединений происходит в результате диспропорционирования перекисных радикаловThe oxidative conversion of gaseous alkanes C3-C4 in the barrier discharge plasma into valuable oxygenates is investigated. The process of transformation has the single stage and carried out without catalyst using and under on the temperature of environment. The main products are hydroxyl and carbonyl compounds with the amount of carbon atoms equaled to the same amount of carbon atoms in initial gaseous hydrocarbons as opposed to partial oxidation of propane and butanes with the main products of methanol, acetaldehyde, formaldehyde, lower carbon acids, and carbon oxides. To avoid the formation of deposit on the electrode surface we add vapors of liquid hydrocarbon (octane) into a gaseous hydrocarbons feedstock. The mechanism of gaseous alkanes oxidation process implying the dissociation of oxygen and alkane molecules by means of the impact of barrier discharge electron is proposed. The proposed mechanism of oxidation of gaseous hydrocarbons resembles the mechanism of oxidation of liquid alkanes. In both cases the main products (hydroxyl and carbonyl compounds) are produced due to the fact of undergoing of the disproportination reaction of the peroxide radical

Nanosecond-Laser Generation of Nanoparticles in Liquids: From Ablation through Bubble Dynamics to Nanoparticle Yield

A comprehensive picture of the nanosecond-laser generation of colloidal nanoparticles in liquids is nowadays the demand of their high-throughput industrial fabrication for diverse perspective biomedical, material science, and optoelectronic applications. In this study, using silicon as an example, we present a self-consistent experimental visualization and theoretical description of key transient stages during nanosecond-laser generation of colloidal nanoparticles in liquids: plasma-mediated injection of ablated mass into the liquid and driving the vapor bubble, finalized by the colloid appearance in the liquid. The explored fundamental transient stages envision the basic temporal and spatial scales, as well as laser parameter windows, for the demanded high-throughput nanosecond-laser generation of colloidal nanoparticles in liquids

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

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

Large-Scale Laser Fabrication of Antifouling Silicon-Surface Nanosheet Arrays via Nanoplasmonic Ablative Self-Organization in Liquid CS₂ Tracked by a Sulfur Dopant

Large-scale surface nanopatterning of a commercial silicon (Si) wafer in the form of regular 1D arrays of high-aspect-ratio vertical nanosheets (NSs) for antifouling and other potential promising optoelectronic, nanophotonic, and sensing applications was performed via multishot picosecond IR-laser ablation under a 5-mm-thick carbon disulfide liquid layer. Specifically, the nanopatterned surface layer demonstrates the broad ultralow mid-IR transmittance and the high content of sulfur, carbon, and even oxygen in the modified submicron-thick top layer, preventing the appearance of a <i>Staphylococcus aureus</i> bacterial biofilm. High-resolution transmission electron microscopy studies exhibit the anticorrelating inner versus outer surface abundance of donor sulfur versus adverse carbon and oxygen components and the amorphous structure of the sulfur-hyperdoped NSs atop their crystalline basements. These NSs indicate their appearance via the interfacial vapor/plume bubble-mediated codeposition of Si ablation nanoplumes from the regular trenches and sulfur-containing products of carbon disulfide decomposition in the bubble. Numerical modeling indicates the nanoplasmonic origin of the Si NSs, self-limited in both the 100 nm periods and the submicron heights