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New applications, in particular in medicine, require the creation of track-etched membranes (TMs) with fundamentally new properties. There are well-known TMs made from polycarbonate, polyimide, polypropylene, polyethylene terephthalate, polyethylene naphthalate, and polyvinylidene fluoride; that is, polymers characterized by high chemical resistance. This study focuses on the development of a membrane made of the biodegradable polymer polylactic acid (PLA). Films prepared from a 1% solution of polylactic acid with a molecular weight of Mw = 121000 g/mol were taken as the initial matrix for TM fabrication. The films were irradiated with 1.2-MeV Xe ions at a fluence of 3.1 × 107 cm−2 on an IC-100 cyclotron. Etching was carried out in NaOH solutions of various concentrations (0.1, 1, or 2 mol/L) with varying the temperature from 18 to 70°С and the treatment time from 5 to 30 min. It has been revealed that the optimal treatment conditions for irradiated PLA films are etching in 1 M NaOH at a temperature of 44°C. This mode, with a time variation from 10 to 30 min, makes it possible to obtain through pores with a diameter of 0.6 to 1.5 µm with channel geometry close to cylindrical. It has been found that an increase in the etching time over 20 min leads to a decrease in the roughness of both membrane sides.

Effects of the low-temperature plasma exposure, γ-irradiation, and joint g-irradiation and plasma exposure on the structure and surface properties of thin films based on polylactic acid (PLA) have been investigated. Films were obtained by the method a solvent-casting. It has been shown that films based on polylactic acid have topographically different sides: a smoother inner side and embossed outer one. PLA films have properties close to those hydrophobic, with a contact angle in the range of 70°-73° regardless of the surface side and belong to a weakly polar materials. The combined effect of plasma and gamma radiation slightly changes the surface topography. The effect of low-temperature plasma on the surface of the films leads to a decrease in the contact angle by 13°-55° (9-11%) and an increase in surface energy due to the polar component. The results of in vivo experiments on rabbits are presented. Biomicroscopy, optical coherence tomography, morphological and electron microscopic examination of the cornea after implantation of initial and radiation and plasma treated films showed that implantation of the films in the anterior chamber is not accompanied by a pronounced inflammatory reaction and increased intraocular pressure, while maintaining the morphological structure of the cornea almost unchanged.

To determine the effect of intracameral implantation of polylactic acid (PLA) films modified in low-temperature atmospheric pressure plasma on the course of in vivo-induced bullous keratopathy (BK).

The influence of modification by low-temperature atmospheric-pressure plasma and steam sterilization on the properties of track membranes based on polyethylene terephthalate is studied. It is found that the action of hot steam under pressure changes the topography of the surface of the membranes with the formation of artifacts in the form of large oval-shaped protrusions with a height of 300–400 nm and a density of up to 0.007 protrusions/μm2 on the surface, increases the surface roughness by 40% and the wetting angle by 9°–18° for the initial membranes and by 36.8°–39.6° for the membranes modified in plasma, and decreases their surface energy to the initial value of 33 mJ/m2. Despite the morphological and structural changes in the surface, sterilization by hot steam under pressure does not lead to any noticeable change in the surface charge and ζ potential of the track membranes. Hot steam under pressure does not promote further crystallization of the membrane, keeping the polymer with a crystalline phase of 40–42%. Thus, to preserve the properties acquired by the membrane after the plasma treatment, it is necessary to search for a different sterilization method (gamma radiation, ethylene oxide sterilization).

Effect of plasma modification of surface and sterilization processes on optical characteristics of a polyethylene terephthalate (PET) track membrane (TM) is studied. The TMs are fabricated with the aid of irradiation of PET using 40Ar+8 ion beam and etching in a 1.5-M solution of NaOH. The TMs are modified using low temperature plasma and sterilized with the aid of autoclave treatment and gamma irradiation. The PET TMs exhibit low transmittance and refractivity due to formation of structural inhomogeneities and polymer crystal structure. The effect of plasma and sterilization leads to a decrease in the TM transmittance owing to an increase in the degree of crystallinity and formation of membrane artifacts.

This paper presents data on the effects of steam sterilization on the properties of thin films based on polylactic acid. It has been established that thin films based on polylactic acid and poured from solutions of 10, 20, and 30 g have two topographically different sides. One side (internal) has a more prominent surface. The other side (external) has a smooth surface. It is reflected in the roughness parameters. Ra of the internal side varies from 0.01 to 0.018 μm. Ra of the external side is 0.17–0.4 μm. The average roughness increases from 0.17 to 0.4 μm with an increase in the mass of the solution poured into films. Sterilization contributes to a change in the surface of the polylactic acid films and makes their profile more prominent. This leads to a significant increase in the roughness of both sides by more than 5 times. In addition, it was found that thin polylactic acid films have hydrophobic (θ = 80°) properties. Steam sterilization reduces the wetting angle by 14°–15° (17–18%) and increases the surface energy values to a greater extent owing to the polar component. These changes increase the hydrophilicity of the studied material.

—The article presents the results of studying the mechanical characteristics and tribological properties of PET track-etched membranes (TM) obtained by irradiating PET films with argon ions and subsequent etching. The article also shows the changes in the TM mechanical and tribological properties after radiation and steam sterilization. It is established that the sterilization process reduces elongation at break, the Young’s modulus, relative yield strength, and tensile stress. Tribological tests of TM demonstrated a friction coefficient of 0.08–0.17. The tests also showed the nature of the counterbody impact on the material surface, manifested in the formation of “grooves” of various sizes, “jamming” of the surface, and change in pore shape. It was established that TM sterilization does not significantly affect the behavior of the friction coefficient or nature of counterbody impact on the membrane surface.

The roughness of a milled surface is investigated for AISI 321 austenitic stainless steel with different structure and mechanical properties. The grain size is modified by familiar methods of intense plastic deformation: ABC pressing and rolling. For milling, stainless-steel plates of different thickness are prepared. Cylindrical hard-alloy mills are employed. Analysis of the microgeometry of the machined surface indicates that change in structure and mechanical properties by intense plastic deformation decreases the height parameters Sa and Sz of the roughness by factors of 1.8–6.7.

The article presents a critical assessment of the use of polymeric materials in keratoplasty, describing possible postoperative complications. The benefits and disadvantages of implanting various bio-compatible polymers: glyceryl-methacrylate, plastics ACR-7, plexiglass, polymethylmethacrylate, gelatin, hydrogel, and its modifications and others. The significant part of the article focuses on the use of biopolymers, many of which, according to studies, cause an inflammatory reaction, reorganization of collagen fibers and the change of the implant itself. A separate aspect of the article is the use of biodegradable polymers in keratoplasty. The great benefits of using these materials are the ability to control the rate of biodegradation by changing their structure by adding anions and cations superficially active substances. Of all the forms of polymers suitable for ophthalmology in keratoplasty, microspheres, films, and membranes have become very popular. Numerous studies using biodegradable materials have shown that despite the disadvantages (high cost, the complexity of manufacturing), of this type of polymers have great potential in the treatment of various corneal diseases. Keywords: Keratoplasty, polymeric materials, cornea, biodegradable materials, biocompatibility.

On account of their improved physicomechanical characteristics, materials with ultrafine-grain and nanocrystalline structure are of great interest in manufacturing and elsewhere. There has been considerable research on methods of producing such materials. The techniques most commonly used to produce three-dimensional ultrafine-grain materials are equal-channel angular pressing; cumulative rolling; intense rolling; and friction with mixing. However, little information is available regarding the influence of the shaping conditions on the structure and properties of three-dimensional ultrafine-grain materials. Accordingly, there is a pressing need to find effective structuring and shaping methods for the manufacture of parts from ultrafine-grain materials with enhanced performance. Analysis of structuring and shaping methods indicates that the production of high-quality parts from three-dimensional ultrafine-grain and nanocrystalline materials calls for the development of processes, equipment, and tools such that the physicomechanical characteristics and structure of the materials formed by intense plastic deformation are retained.

The influence of cutting (milling) on the surface roughness and undulation of AMg2 aluminum alloy with regular and ultrafine grain structure is considered. In the machining of materials with ultrafine grain structure, the surface quality is better than for materials with regular grain structure.

Currently, much attention is paid to low-temperature atmospheric-pressure plasma as an agent for gentle antimicrobial decontamination. In this work, data on the efficiency of low-temperature plasma for antimicrobial decontamination of polyethylene terephthalate track membranes used as corneal implants in keratoplasty are presented. The obtained results show that 30-, 60-, and 90-s exposure to low-temperature plasma has a gentle decontaminating effect on track membranes.

The purpose of this research is the study the influence of the plasma-modified PLA films implantation on the morphology of the cornea in vivo experiment. Studies were performed on 12 pubescent female Sylvilagus bachmani rabbits. Plasma-modified PLA films were implanted into the anterior chamber of one animal eye. The feedstock for the films was obtained by dissolving PLA in the chloroform. Modification of the films was carried out using the low-temperature plasma. Such methods as visual check, photographic registration, non-contact ocular tonometry and optical coherent tomography of cornea were also used in the course of the experiment. Sampling was performed on day 21 after the start of the experiment for morphology studying. Results showed that the implantation of the plasma-modified PLA films contributes to the development of the mild inflammatory response (mild leukocyte infiltration, newly formed blood vessels, increased twisted stroke of collagen fibers, and presence of strongly acid sulfated GAGs) as a result of the surgery. The study showed the possibility of PLA films using as a corneal implant.

The purpose of this research is the study the influence of the plasma modification on PCL films properties and the influence PCL films implantation on the morphology of the cornea in vivo experiment. The feedstock for films was obtained by dissolving PCL in the chloroform. Modification of the films was carried out using the low-temperature plasma. Studies were performed on 4 pubescent female Sylvilagus bachmani rabbits. The PCL films were implanted into the cornea of one animal eye. Sampling (animal's eyes) was performed on day 21 after the start of the in vivo experiment for morphology studying. Results showed that the plasma modification increases a roughness (1.5 times) of PCL films, the hydrophilicity of films, reducing the contact angle of the inner side by 9°–10° (12%–14%), and increases the surface energy values mainly due to the polar component to 20.6±0.3 mJ/m2. The implantation of the PLA films contributes to the development of the inflammatory response as a result of the surgery and implantation of the polymer material. The study showed the possibility of the plasma-modified PLA films using as a corneal implant in the future.

Turning by tools that are characterized by a linear or curved cutting blade but have no cutting tip is studied experimentally. The influence of the depth and cutting speed, the supply, and the cutter inclination on the components P z and P y of the cutting force is investigated in inverse and direct cutting.

Physical and chemical properties of the surfaces of polyethylene-terephthalate (PET) track membranes (TMs) exposed to low-temperature atmospheric plasma and to γ radiation produced by 60Co isotopes are studied. It is established that the exposure to plasma leads to changes in the chemical composition of the surface and increases the number of polar (carbonyl and carboxyl) functional groups in a thin near-surface layer of a TM. The surface energy is also shown to grow owing to its polar component and surface reconstruction. The reconstruction consists in the growth of surface roughness owing to oxidation-reduction reactions, followed by the appearance of destructive areas. These changes promote a lyophilic behavior of the track-membrane surface. Subsequent γ irradiation of the surface is shown to reduce the plasma-modified TM undulation, while decreasing the number of destructive areas and bringing the material into a more equilibrium state.

A study on the use of track etched membranes (TM) based on the polyethylene terephthalate (PET), including those modified with cold plasma, followed by layering of prenatal stromal cell (PSC) culture on the material surface in vitro in the surgical treatment of a bullous keratopathy (BK) of the cornea has been conducted. The study was conducted on 16 Sylvilagus bachmani rabbits, which after BK modelling were divided into 4 groups: the 1st group was a control group of 4 animals (4 eyes); the 2nd group was a group of 4 animals (4 eyes) which were implanted by TM; the 3rd group was a group of 4 animals (4 eyes) which were implanted by TM with cells; the 4th group was a group of 4 animals (4 eyes) which were implanted by plasma modified TM with cells. TM was obtained by irradiating PET with 40Ar+8 ions and subsequent chemical etching. Eyes were enucleated for histological examination after 8 weeks from the start of the experiment. As a result of the research, it was found that the implantation of TM with a preliminary layering of human PSC promotes the growth of the fibroblast population in the cornea stroma and forming of the leukocyte (lymphocytic and eosinophilic-basophilic) infiltration compared with the implantation of TM without a cellular component. In addition the implantation of TM contributes to a twofold decrease in the induced by BK cornea edema.

The purpose of this research is the study of the influence of thin polylactic acid films implantation on the corneal morphology in vivo experiment. Studies were performed on 8 pubescent female Sylvilagus bachmani rabbits. Polylactic acid films were implanted into the anterior chamber of one animal eye. The feedstock for the films was obtained by dissolving polylactic acid in the chloroform. Before the implantation PLA films were sterilized. The overall duration of the in vivo experiment comprised 21 days. Such methods as visual check, photographic registration, non-contact ocular tonometry and optical coherent tomography of cornea were also used in course of the experiment. Sampling was performed on day 21 after the start of the experiment for morphology studying. Results showed that the implantation of the PLA films into the anterior chamber of eye does not induce an inflammatory reaction and does not increase an intraocular pressure. The study showed the possibility of PLA films using as a corneal implant.

The paper deals with an experimental study of the dynamics of frictional processes in the friction of bulk ultrafine-grained materials. As model samples, an aluminum alloy 5052 was used with an ultrafine-grained structure formed by the method of equal-channel angular pressing. In the process of dry sliding friction, the signals of vibration acceleration and acoustic emission were recorded.

The possibility of using the acoustic emission method for monitoring the cutting process mode is considered. The influence of mechanical chatter in the technological system on the parameters of acoustic emission signals has been experimentally revealed. It is established that a short-term drop in the acoustic emission spectral power is observed in the transition from a steady to a chatter cutting regime. In the region of high-amplitude vibrations, the time dependencies of median frequency of the AE decreases, while that of the spectral power increases sharply.

The effect of heat treatment on structure and phase composition of austenitic stainless steel AISI 321 has been considered. The structural studies were performed using transmission electron microscopy, and the phase composition has been determined by the X-ray diffraction method. It was established that the use of severe plastic deformation (SPD) allowed reducing the content of α-phase, while subsequent heat treatment increased it.

The article shows results of low temperature plasma and steam sterilization influence on the PET track-etched membrane surface properties. The track-etched membranes were modified by the atmospheric low-temperature plasma with a processing time of 30 s and were sterilized by the steam sterilization in two modes: 130–132°C at a pressure of 0.2 MPa (5 min); 120–121°C at a pressure of 0.11 MPa (20 min). The results showed that the steam sterilization increased the values of roughness and surface hydrophobicity of the membranes after plasma modification. The changes were primarily associated with surface degradation and hydrolysis reaction, which led to decarboxylation, cyclization and, as a result, an increase in cyclic trimmers on the PET surface. An increase in the time of steam sterilization led to an increase of the number of cyclic oligomers on the surface, which was manifested in significant morphological, physical and chemical changes (changes in roughness, reduced hydrophilicity of the surface).

The purpose of this study is to investigate the possibility of forming an eyeball musculoskeletal stump using a Ni-Ti implant in vivo. Studies were performed on 18 Wistar rats. The animals were enucleated one of eyes. After the enucleation the musculoskeletal stump using Ni-Ti implant was formed. Ni-Ti implant was made from a thread of porous Ni-Ti (TN-10) with a thickness of 100 [mu]m. Before implantation the Ni-Ti implant was sterilized by ethylene oxide. Results showed that the Ni-Ti implant surface was uniform and had not visible defects. The NiTi implant surface was a hydrophobic with the mean value of [theta]=93.5°±1.4. The Ni-Ti implant in the eye orbit was mobile. The Ni-Ti implantation into the eye orbit contributed the connective tissue with blood vessels formation and insignificant leucocytes infiltration (macrophages and lymphocytes infiltration). The study showed the possibility of forming an eyeball musculoskeletal stump using a Ni-Ti implant.

The effect of equal-channel angle pressing (ECAP) conditions on wear resistance and adhesion of the resulted ultrafine grained AA6063 in sliding against a steel ball has been investigated. Using the 3D laser confocal microscopy the parameters of wear and adhesion transfer layer thickness on ultrafine grained AA6063 has been measured. As it was established, the ECAP at room temperature allowed forming AA6063 microstructure in sliding, which is more wear resistant and less prone to adhesion as compared to the previous one at higher temperatures. The effect of ECAP pass number n on the above parameters becomes negligible for n > 8. The wear resistance of AA6063 processed by ECAP at 200°C is improved only for n = 4 whereas n > 4 has only a negative effect.

Automatization of engineering processes requires developing relevant mathematical support and a computer software. Analysis of metal cutting kinematics and tool geometry is a necessary key task at the preproduction stage. This paper is focused on developing a procedure for determining the geometry of oblique peakless round-nose tool lathe machining with the use of vector/matrix transformations. Such an approach allows integration into modern mathematical software packages in distinction to the traditional analytic description. Such an advantage is very promising for developing automated control of the preproduction process. A kinematic criterion for the applicable tool geometry has been developed from the results of this study. The effect of tool blade inclination and curvature on the geometry-dependent process parameters was evaluated.

The effect of ECAP pass number on wear, microhardness and tribological dynamic behavior of UFG Al– 6 wt % Mg alloy has been studied. The UFG Al–6 wt % Mg samples demonstrated higher wear resistance after 4 and 8 ECAP passes as compared to as-received alloys state. The dynamics of sliding and loudness level generated in sliding showed moderate increase of vibrations and noise on ECAP UFG samples.

The effect of AE sensor positioning on the bulk ultrafine-grained materials used for sliding against steel ball has been investigated. Two versions of AE sensor positioning have been tested and showed the different attenuation levels. The experimentally obtained AE signal waveforms have been analyzed under the AE signal parameters such as a median frequency and AE energy. It was established that the AE sensor positioned on the sample supporting plate in the vicinity of the sample tested allowed redistribution of the signal energy from a low-frequency to high-frequency range as well as extending the median frequency range as compared to those obtained by mounting the sensor on the immobile sample holder.

One of the major problems in the acquisition of units of the Armed Forces is timely detection of individuals with deviant behaviour, which are prone to delinquent and addictive behaviour. The article presents the results of an analysis of existing methodologies aiming to identify servicemen abusing and occasionally using narcotic drugs and psychotropic substances. The characteristics of the proposed new automated complex psychological diagnosis socially determined behavioural disorders and methods is given. The high efficiency of this characteristics in the allocation among "at risk" servicemen is given.

Monitoring of the edge clamped workpiece deflection during milling has been carried our using acoustic emission, accelerometer and eddy current sensors. Such a monitoring is necessary in precision machining of vital parts used in air-space engineering where a majority of them made by milling. The applicability of the AE, accelerometers and eddy current sensors has been discussed together with the analysis of measurement errors. The appropriate sensor installation diagram has been proposed for measuring the workpiece elastic deflection exerted by the cutting force.

The results of experiments with high load and sliding speed sliding conditions on tribologically mated pairs such as steel 1045/steel 1045 (test 1), steel 1045/basalt (test 2) and Hadfield steel/basalt (test 3) have been carried out in order to identify their response in terms of the acoustic emission and vibration signals. The steel to rock and rock to steel transfer has been revealed by examining the worn surfaces of both steel and rock samples with the use of laser scanning microscopy. The AE signal characteristics have been determined for the tribological pairs studied. The dynamics of sliding has been evaluated by measuring the vibration accelerations. Relationship between wear mode and either acoustic emission signal or vibration signal has been established. The minimal vibration oscillations amplitude and acoustic emission signal energy have been found out in sliding Hadfield steel/basalt pair.

Microtexturing the metal cutting tool surfaces is a novel technique intended for enhancing the workability of these tools. The microtexturing is used in machining the titanium alloys for air-space applications for reducing the adhesion wear of metal cutting blades. This paper is focused on forming the microtextured dotted, banded and overlapped areas on the surfaces of high-speed steel samples. The treated areas have been examined using laser scanning microscopy for the microtexture pattern and roughness. It has been shown that the microtextured surfaces obtained on the high-speed steel samples were free of cracks. Surface pattern and roughness of all three microtextured areas have been examined and analyzed.

Polyethylene terephthalate (PET) track membrane (TM) has a great opportunity to use as a bio implant in ophthalmology's surgery due to its physical and chemical properties and biological comparability. Sterilization of medical implants can change its properties and can influence on regeneration process and success of surgical treatment. We researched influence on the PET track membrane of two sterilization methods wide used in medicine. The first sterilization method was steam sterilization. The second method was γ-irradiation of Co{60} radionuclide sterilization. The sterilization processes influence on the track membrane properties was assessed by surface topography analysis, IR Fourier spectroscopy, wettingangle and surface energy of TM surface measurement.

The earthmoving of permafrost soil is a critical task for excavation of minerals and construction on new territories. Failure by abrasive wear is the main reason for excavation parts of earthmoving and soil cutting machines. Therefore investigation of this type of wear is a challenge for developing efficient and wear resistant working parts. This paper is focused on conducting tribological experiments with sliding the steel samples over the surface of diabase stone sample where abrasive wear conditions of soil cutting are modeled experimentally. The worn surfaces of all samples have been examined and transfer of metal and stone particles revealed. The acoustic emission (AE) signals have been recorded and related to the results of worn surface analysis. he acoustic emission (AE) signals have been recorded and related to the results of worn surface analysis. As shown the wear intensity correlates to that of acoustic emission. Both acoustic emission signal median frequency and energy are found to be sensitiv...

The erosion plume resulting from ablation of copper and tantalum targets in vacuum with excimer laser irradiation (308 nm) was studied using Langmuir probe and optical emission spectroscopy. The ion and electron probe currents were obtained in the range of energy densities from 0.2 to 2.2 J/cm2 at the target with a probe-to-target distance from 10 to 133 mm. The ion velocity distribution calculated from the time-of-flight measurements has been revealed as a multimodal kind. Curves of the spatial and time dependence of electron probe current were obtained in real time. The electron temperature of different plume regions was determined from a series of I-U characteristics taken at different distances between the Langmuir probe and target. It was established that the plume electron temperature is nonuniform and it has a maximum in front of the plume. The optical emission spectra were used to study the plume composition qualitatively. In addition, the optical emission spectroscopy allowed us to measure both t...

In the given work we present the results of experimental estimation of chip shrinkage under turning with straight and radius cutters for two schemes of cutting: "direct" and "reverse". Ratios of thickening, broadening and longitudinal shrinkage of the chip were established as shrinkage parameters. The given paper presents the graphic charts showing dependences of shrinkage upon cutting depth, supply and cutting edge inclination which indicate the deformations taking place in the cutting area when cutting with cup-tip cutters. The authors show the significant difference in the character and degree of chip shrinkage when working according to various schemes of cutting.

The erosion plume resulting from an ablation of a tantalum target in vacuum with an excimer laser radiation (308 nm) was studied using the Langmuir probe technique. The spatial and temporal dependencies of the electron probe currents were obtained in real time. The electron temperature of different plume regions was determined from a series of I–U characteristics taken at different distances between the probe and the target. We determined that the plume electron temperature is non-uniform and has a maximum value in front of the plume.

A Langmuir probe was used to study the erosion plume produced during the ablation of a tantalum target in vacuum by radiation from an excimer laser at 308 nm. The spatial and temporal dependences of the electron and ion currents of the probe were obtained in real time. The electron temperature of different regions of the plume at different distances from the target was measured for the first time from a series of dependences of the electron probe current on the probe voltage. The nonuniformity of the electron temperature and its lowering in different plume regions with increasing expansion time were determined. The ion density in the plume was determined at different distances from the target.

The laser plasma plume expansion induced by UV nanosecond irradiation from metallic Nb and Ta targets has been studied using Langmuir probe time-of-flight measurements. The ion current shape was measured as a function of the laser radiation flux at various probe-to-target distances. The ion velocity distribution and the ion energy spectra have been determined by measuring the time of flight of ions reaching the Langmuir probe. A multi-mode velocity distribution of ions has been revealed. The dependence of the amplitudes of the plume energy components on the plume scatter time and on the laser radiation flux has been investigated. The experimental time-of-flight data have been compared with a Maxwell velocity distribution. The threshold values of the laser intensity were determined for different distribution modes in the ion energy spectrum.