Structural defects and heteroatoms play a key role in electrochemical reactions. However, there is still no common understanding of what has a greater impact on electrochemical processes: defects or the type of heteroatoms. To clarify these factors, defective carbon nanowalls treated by reactive etching in different atmospheres, such as argon and mixtures of argon with nitrogen, chlorine, hydrogen bromide, and sulfur fluoride were used. Properties of the obtained samples were analyzed with Raman spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and cyclic voltammetry. The results of the study showed that the plasma modification of carbon nanowalls leads to the removal of the amorphous layer and subsequent implantation of heteroatoms, which ultimately leads to an increase in their areal capacitance 1.5-fold in a 1:2 argon - nitrogen mixture and 2-fold in a 1:4 argon-nitrogen mixture.

Based on regular porous polymeric membranes, the synthesis of metal and dielectric spearhead structures with given morphological characteristics was carried out. Copper structures with the ~ 1 μm height and dielectric spearhead microstructures made from iodic acid with the 12 μm height and 1 μm diameter were obtained. The possibility is discussed of using such optical elements to solve the problems of increasing the efficiency of IR radiation detection, signal amplification and conversion to visible and near-infrared ranges. Keywords: regular membranes, spearhead structures, copper, iodic acid, radiation transformations.

Laser lithotripsy using optical fiber to fragment salivary gland stones (sialoliths) is currently one of the most successful methods for treating salivary stone disease. It is important to reduce the fragmentation time of extremely hard salivary stones, which in practice is more than three hours in the case of large stones. We present new approaches to lithotripsy related to the use of radiation from a nanosecond thulium-doped fiber laser at a wavelength of 1.94 μm. The study is performed using gypsum phantoms and sialoliths. Parameters of laser exposure are determined that provide a high rate of lithotripsy without significant heating of surrounding tissues. It is shown that the mechanism of action of nanosecond laser radiation, which is well absorbed in water upon fragmentation of stones, is associated with the burnout of the binding organic material of sialolite and the explosive boiling of water. The results obtained can serve as the basis for the development of new promising medical technology.

This paper presents the development of a superconducting nanowire single-photon detector (SNSPD) integrated into a distributed Bragg reflector (DBR) with a design center wavelength of 830 nm and a bandwidth of 200 nm. This SNSPD is made of a superconducting niobium nitride (NbN) thin film that is produced using plasma-enhanced atomic layer deposition. The DBR is made of 15 alternating layers of silicon nitride and silicon oxide that are produced through plasma-enhanced chemical vapor deposition. The reflection efficiency of the mirror is 90% at a wavelength of 830 nm. For sufficient optical coupling, an optical micro-connector optimized for multimode or single-mode optical fibers with a diameter of 128 mu m was formed using two-photon polymerization techniques. The niobium nitride film was deposited onto the DBR surface in-situ in two separate reactors connected by a vacuum transfer. The in-situ technique of deposition of a superconducting niobium nitride film and a DBR has allowed achieving a system detection efficiency of 90% at a wavelength of 830 nm and a dark count rate of 10 s-1 at a temperature of 2.5 K. Additionally, the detector jitter was 50 ps.

This paper presents the results of studying the process of laser formation of microstructures from silver nanoparticles in nanoporous quartz glasses. Glass samples were impregnated with organometallic molecules Ag(hfac)COD in a supercritical carbon dioxide environment. The formation of point and linear microstructures was carried out by high-frequency (70 MHz) femtosecond laser radiation with a wavelength of 525 nm and energy in the pulse up to 1 nJ. It was found that the formation of microstructures occurs due to photo- and thermal decomposition of precursor molecules with the formation of plasmonic silver nanoparticles. It is shown that the developed temperatures can exceed the melting point of glass, which leads to the appearance of microstructures with altered refractive index. A qualitative model explaining the individual stages of cluster formation in the glass volume under point laser impact is presented.

features of the phenomena of a laser nanosecond radiation In supercritical carbon dioxide are revealed. It is shown that the presence of a supercritical fluid leads to the expansion of the structures formed on the target in comparison with the air media. It has been suggested that the resulting magnification effect is due to the defocusing of the system, which causes the formation of the lens impact. Obtaining useful results is possible with the use of various technologies of laser ablation and microstructuring in supercritical fluids.

features of the phenomena of a laser nanosecond radiation In supercritical carbon dioxide are revealed. It is shown that the presence of a supercritical fluid leads to the expansion of the structures formed on the target in comparison with the air media. It has been suggested that the resulting magnification effect is due to the defocusing of the system, which causes the formation of the lens impact. Obtaining useful results is possible with the use of various technologies of laser ablation and microstructuring in supercritical fluids. Keywords: nanosecond laser radiation, supercritical fluid, metal target, fluctuations.

Three methods of obtaining regular porous structures in polyethylene-terephthalate polymer films are considered. A film is irradiated with synchrotron radiation at an X-ray lithography station through a mask based on a tantalum membrane perpendicular to its surface, followed by the chemical etching of destruction zones. To form regular porous structures, the method of polymer etching with a focused ion beam in a scanning electron microscope is used. This method enables variation of the diameter of the formed channels, the distance between them, and precludes chemical etching of the destroyed polymer, which provides a smoother pore surface. The pores are formed using nanosecond- and femtosecond-laser radiation in the nonlinear absorption mode. For femtosecond and nanosecond sources, optimal parameters of laser action on the film samples are selected, resulting in the formation of through pores in a single laser pulse.

Based on regular porous polymeric membranes, the synthesis of metallic and dielectric spearhead structures with given morphological characteristics was carried out. Copper structures with 1 μm height and dielectric spearhead microstructures made of iodoic acid with 12 μm height and 1 μm diameter of were obtained. The possibility of using such optical elements to solve the problems of increasing the efficiency of IR radiation detection, signal amplification and conversion to visible and near-infrared ranges.

The paper studies the formation, development and stabilization of the structure of foamed amorphous D,L-polylactide after a slow (quasi-isothermal) and a fast (quasi-adiabatic) relief of the pressure of supercritical carbon dioxide used as a plasticizing/foaming agent. The following regularities have been established: (1) the values of the foam expansion factor in the process of quasi-adiabatic depressurization are significantly lower than in the quasi-isothermal regime because of significant dissipation of the “polymer–foaming agent” system internal energy due to the internal friction in the system; (2) an expansion-collapse effect is observed during the quasi-isothermal foaming; (3) at the intermediate stage between nucleation and intensive foam development, the pore nuclei growth in the plasticized polymer is self-similar. The results obtained are important for selecting foaming regimes that provide the synthesized highly porous matrices with the structural characteristics required for their use in regenerative medicine and tissue engineering.

The article is devoted to one of the effective technologies for processing solid transparent materials—thermoplasmonic laser-induced backside wet etching (TP LIBWE). This technology involves aqueous solutions of metal precursors as a working medium. The dependence of the efficiency of sapphire TP LIBWE micromachining on the parameters of laser action is studied with the aqueous solution of the AgNO3 precursor as a working media. The near-optimal range of laser intensities from the point of the etching speed and quality is found. Utilizing the optoacoustic methods, high-speed video, and an optical integrating sphere, the initial stage of the TP LIBWE process is studied in detail. A four-stage model of the TP LIBWE beginning process is proposed, which explains the effects from the beginning of Ag nanoparticle formation in the region of laser exposure to the transition of the TP LIBWE process to a stationary laser microstructuring mode. It is shown that effective microstructuring occurs due to the appearance on the sapphire surface of a thin modified layer in the region of laser action. This thin modified layer is an amorphous Al2O3 with numerous plasmonic Ag nanoparticles inside it and at the sapphire/liquid interface.

To obtain a supported heterogeneous catalyst, laser ablation of metallic palladium in supercritical carbon dioxide was performed in the presence of a carrier, microparticles of γ-alumina. The influence of the ablation process conditions—including supercritical fluid density, ablation, mixing time of the mixture, and laser wavelength—on the completeness and efficiency of the deposition of palladium particles on the surface of the carrier was studied. The obtained composites were investigated by scanning and transmission electron microscopy using energy dispersive spectroscopy. We found that palladium particles were nanosized and had a narrow size distribution (2–8 nm). The synthesized composites revealed high activity as catalysts in the liquid-phase hydrogenation of diphenylacetylene.

A laboratory system for the development of new approaches to the experimental study of nucleation and formation of three-dimensional structures in nonequilibrium “polymer-supercritical fluid” heterogeneous systems has been designed and produced. The system is designed to conduct a comprehensive analysis of these processes at various stages starting from supercritical fluid plasticization of the initial polymer, followed by its subsequent nucleation and passage to the glass transition stage of the foamed polymer matrix, providing an opportunity for adequate interpretation.

The article demonstrates the fundamental possibility of creating microstructures for various functional purposes using the capabilities of the two-photon femtosecond polymerization method. The developed technological approach for creating a micro-optical holder for standard single-mode and multimode fibers is demonstrated. This type of holder can be used to manufacture a unit for optical matching of optical fibers with sensitive optical elements. The possibility of optical matching of fibers with a superconducting single-photon detector, an array system of bolometric superconducting microbridges, and spherical self-formed microlenses by near infrared-sensitive photopolymerization has been experimentally shown. The device manufacturing process was carried out in a combined single laser micromachining facility using femtosecond laser radiation for lithography with submicron resolution, texturing of the sensor surface, and the formation of microstructures for installing single-mode optical fibers.

An apparatus for 3D laser printing by the two-photon polymerization technique using a scheme for spatiotemporal focusing of femtosecond laser radiation is described. The system, which is based on available components) allows the formation of 3D centimeter-size structures with the micron resolution in all directions; this is its main advantage over other systems, including commercial ones. When creating the apparatus, a minimum number of optical and optomechanical components were used, thus significantly increasing the accessibility of such apparatuses in various laboratories. This apparatus can be used to manufacture 3D structures for various purposes, including scaffold structures for tissue-engineering tasks.

A device for laser bioprinting is described, whose principle of operation is based on the transfer of a microscopic amount of gel with living systems from a donor substrate under the action of nanosecond laser pulses to arbitrary (acceptor) substrates. The use of a nanosecond pulsed laser source, a P-shaper lens, and a motorized telescopic system in the device makes it possible to automatically adjust the parameters of the laser action for various tasks. Using the device it is possible to carry out laser printing of microorganisms, cells, and their agglomerates of various sizes and physical properties. The device allows one to select parameters that provide stable printing modes and minimize negative factors that affect the transferred living microorganisms using gels of various viscosities.

The mechanisms that control the nucleation kinetics in foamed amorphous D,L-polylactide, which was preliminary plasticized using subcritical or supercritical carbon dioxide, were determined by analyzing the video data on the depressurization-induced quasi-isothermal (313.3 K) foaming of the polymer. Possible scenarios of phase separation in the polylactide–carbon dioxide system at the stage preceding active foam formation were considered.