The quality of modern measuring instruments has a strong influence on the speed of diagnosing diseases of the human musculoskeletal system. The research is focused on automatization of the method of gait analysis. The study involved six healthy subjects. The subjects walk straight. Each subject made several gait types: casual walking and imitation of a non-standard gait, including shuffling, lameness, clubfoot, walking from the heel, rolling from heel to toe, walking with hands in pockets, and catwalk. Each type of gait was recorded three times. For video fixation, the Vicon Nexus system was used. A total of 27 reflective markers were placed on the special anatomical regions. The goniometry methods were used. The walk data were divided by steps and by step phases. Kinematic parameters for estimation were formulated and calculated. An approach for data clusterization is presented. For this purpose, angle data were interpolated and the interpolation coefficients were used for clustering the data. The data were processed and four cluster groups were found. Typical angulograms for cluster groups were presented. For each group, average angles were calculated. A statistically significant difference was found between received cluster groups.

Porcelain fused to metal is widespread dental prosthetic restoration. The survival rate of metal-ceramic restorations depends not only on the qualifications of dentists, dental technicians but also on the adhesive strength of ceramics to a metal frame. The goal of the research is to determine the optimal parameters of the surface machining of the metal frame to increase the adhesion of metal to ceramics. Adhesion of cobalt-chromium alloy and ceramics was investigated. A profilometer and a scanning electron microscope were used to analyze the morphology. To estimate the adhesion the shear strength was measured by the method based on ASTM D1002-10. A method of surface microrelief formation of metal samples by plasma-electrolyte treatment has been developed. Regimes for plasma-electrolyte surface treatment were investigated according to current-voltage characteristics and a surface roughness parameter. The samples were subjected to different surface machining techniques such as polishing, milling, sandblasting (so-called traditional methods), and plasma-electrolyte processing. Morphology of the surface for all samples was studied and the difference in microrelief was shown. The roughness and adhesive strength were measured for samples either. As a result, the mode for plasma- electrolytic surface treatment under which the adhesive strength was increased up to 183% (compared with the traditional methods) was found.

Transcutaneous spinal cord stimulation (tSCS) is a promising noninvasive alternative to epidural stimulation. However, further studies are needed to clarify how tSCS affects postural control. The aim of this study was to investigate the effect of transcutaneous cervical spinal cord stimulation on postural stability in healthy participants via computerized stabilization. The center of pressure and the frequency spectrum of the statokinesiogram were assessed in 14 healthy volunteers under tSCS conditions with frequencies of 5 Hz or 30 Hz, subthreshold or suprathreshold stimulus strength, open or closed eyes, and hard or soft surfaces in various combinations. The results revealed that not all the changes in the center of the pressure oscillations reached statistical significance when the tSCS was used. However, tSCS at a frequency of 30 Hz with a suprathreshold stimulus strength improved postural stability. The use of subthreshold or suprathreshold tSCS at 5 Hz led to a shift of 60% of the signal power to the low-frequency range, indicating activation of the vestibular system. With tSCS at 30 Hz, the vestibular component remained dominant, but a decrease in the proportion of high-frequency oscillations was observed, which is associated with muscle proprioception. Thus, transcutaneous electrical stimulation of the cervical spinal cord may be an effective method for activating spinal cord neural networks capable of modulating postural control.

The development of composite materials and products with a complex internal structure poses questions to develop experimental methods to determine the stress-strain state. Standard experimental methods do not provide a broad picture of the internal changes in the inhomogeneous samples under loading. Moreover, a presence of internal defects, porosity, local buckling can significantly effect on the obtained results. Despite the development of tomography and data processing methods most studies are performed without any external loading on sample. The research presents a methods for studying the porosity of samples under uniaxial compression using an X-ray computed tomography. For this purpose, special equipment that allows loading the sample inside the tomography was made. Additionally, a methodology was developed. The equipment allows not only to transfer the axial compression force, but also to measure the corresponding load value. The equipment was designed to reduce artifactual rays in a place where studied sample mounted. To determine the reference points under loading, a contrasting copper grid was used. A modified Harris detector was used to quantify the displacements. The displacements of the reference points were interpolated to a regular initial grid to estimate the displacements inside the sample. Test samples were designed and manufactured using additive technologies to illustrate the methodology. A series of loadings and tomography scans were carried out for each sample. The tomography data were processed according to the methodology. As a result, the displacement fields of the samples, the values of porosity, volumetric strain and their distribution over the sample for each loading step were obtained.

The application of solid mechanics theory for material behavior faces the discrete nature of modern or biological material. Despite the developed methods of homogenization, there are deviations between simulated and experiments results. The reason is homogenization, which mathematically involves a type of interpolation. The situation gets worse for complex structured materials. On the other hand, a topological approach can help in such analysis, but such an approach has computational costs. At the same time, increasing modern computational capabilities remove this barrier. This study is focused on building a method to analyze material structure in a topological sense. The orientation distribution function was used to describe the structure of the material. The plane case was investigated. Quadratic and biquadratic forms of interpolant were investigated. The persistent homology approach was used for topology analysis. For this purpose, a persistence diagram for quadratic and biquadratic forms was found and analyzed. In this study, it is shown how scaling the origin point cloud influences H₁ points in the persistence diagram. It was assumed that the topology of the biquadratic form can be understood as a superposition of quadratic forms. Quantitative estimates are given for ellipticity and H₁ points. A dataset of micro photos was processed using the proposed method. Furthermore, the supply criteria for the interpolation choice in quadratic or biquadratic forms was formulated.

The purpose of this work is to develop and describe methods for assessing the movement of the subject. The article presents a mathematical formulation of the definition of kinematic parameters, which makes it possible to speed up the diagnosis of the disease and individualize the treatment. The presented methods are maximally general, and it allows to use them for different experimental schemes. And the presented methods are easy to automate. An example of use is also provided. Calculated parameters such as step length, maximum foot lift, and foot swing give a clear indication about the subject moving. Also, the construction of angulograms is informative, the average values of the change in the angles of the hip and knee in steps and the standard deviation are calculated. Angulograms can be used to determine gait in normal and pathological conditions, as well as before and after treatment. Motion is recorded with six Vicon MX cameras (Vicon Motion Systems, Oxford, UK). The data obtained from the cameras are used to calculate the investigated kinematic parameters.