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The problem of selecting suboptimal parameters of an electric propulsion system as part of a spacecraft, ensuring a geostationary orbit raising mission using a Soyuz-5 launch vehicle at the initial launch stage, is investigated. An expression is obtained for the main optimality criterion – the payload relative mass. An algorithm is obtained for solving the problem of parametric optimization of an electric propulsion system as part of a hybrid transportation system. The task of selecting the optimal electric propulsion engine for launching a spacecraft with an electric propulsion system to a geostationary orbit using the launch vehicle under consideration is solved. A design ballistic calculation and a comparative analysis of the obtained data are performed.

The paper presents solutions of the problem of choosing flights of a spacecraft from high elliptic orbits to a geostationary orbit using a stationary plasma engine. The problem of optimal variation of the semi-major axis, eccentricity and inclination, minimizing the discrepancies in these elements with the use of a locally optimal control law that ensures a joint change of these parameters is also solved. An algorithm for determining the weighting coefficients is given; the algorithm ensures simultaneous fulfillment of boundary conditions for the semi-major axis, eccentricity and inclination is given. The results of numerical simulation based on the results of optimization of flights of a communication satellite from a highly elliptical orbit to the geostationary orbit are presented. Based on the results of numerical simulation, plots of the orbit parameters against time are constructed. The results of the data obtained make it possible to draw a conclusion about the possibility of applying a scheme of joint changes in the orbit parameters.

AIM OF STUDY To develop a method for assessing the severity of obstructive jaundice (OJ) of non-neoplastic orogin on the basis of functional parameters of the liver and the activity of pathogenetic agents of hepatodepression.MATERIAL AND METHODS Clinical and laboratory studies of 142 patients with breast cancer of non-tumor origin. The indicators of the functional state of the liver, the index of plasma toxicity for albumin, and the content of malondialdehyde (MDA) were evaluated.RESUlTS Based on the assessment of a number of blood parameters - the content of total bilirubin (TB), the plasma toxicity index for albumin, the MDA level — the severity index of obstructive jaundice of non-neoplastic origin (SIOJ) was developed:SIOJ = IT1/ITn + TB1/TB + 5(MDA1/MDAn)where IT 1 is the plasma albumin toxicity index at the current moment, ITn is the normal albumin plasma toxicity index, TB1 is the current bilirubin content, TBn is the normal bilirubin content, MDA1 is the current malondialdehyde content, MDAn is the normal value. The index less than 13 indicates a mild severity, 14–21 is moderate severity, 22 and higher indicates a severe degree of OJ. The method increases the objectivity of determining the severity of non-neoplastic origin by establishing the severity of liver damage and the processes underlying it.CONClUSiON The suggested clinical and laboratory index allows the severity of obstructive jaundice to be objectively and quickly determined upon admission of a patient to the hospital and also adequate therapy to be initiated in case of severe degree for anticipation of possible post-operative complications, so the treatment should be focused on managing triggers of hepatodepression. The method is simple and available in medical institutions of various levels. The method is especially valuable when used in the dynamics of the early postoperative period.

“Lung-on-a-chip” (LoC) is a microfluidic device, imitating the gas-fluid interface of the pulmonary alveole in the human lung and intended for pathophysiological, pharmacological and molecular-biological studies of the air-blood barrier in vitro. The LoC device itself contains a system of fluid and gas microchannels, separated with a semipermeable elastic membrane, containing a polymer base and the alveolar cell elements. Depending on the type of LoC (single-, double- and three-channel), the membrane may contain only alveolocytes or alveolocytes combined with other cells — endotheliocytes, fibroblasts, alveolar macrophages or tumor cells. Some LoC models also include proteinic or hydrogel stroma, imitating the pulmonary interstitium. The first double-channel LoC variant, in which one side of the membrane contained an alveolocytic monolayer and the other side — a monolayer of endotheliocytes, was developed in 2010 by a group of scientists from the Harvard University for maximally precise in vitro reproduction of the micro-environment and biomechanics operations of the alveoli. Modern LoC modifications include the same elements and differ only by the construction of the microfluidic system, by the biomaterial of semipermeable membrane, by the composition of cellular and stromal elements and by specific tasks to be solved. Besides the LoC imitating the hematoalveolar barrier, there are modifications for studying the specific pathophysiological processes, for the screening of medicinal products, for modeling specific diseases, for example, lung cancer, chronic obstructive pulmonary disease or asthma. In the present review, we have analyzed the existing types of LoC, the biomaterials used, the methods of detecting molecular processes within the microfluidic devices and the main directions of research to be conducted using the “lung-on-a-chip”.

Background. The development of the adjacent level syndrome and, as a consequence, adjacent segment degenerative disease are currently the most common complications of decompression and stabilization surgery with the development of segmental instability.The aim of the study. To conduct a comprehensive neuroimaging assessment of the proximal adjacent segment after rigid fixation and dynamic stabilization in degenerative lumbar disease.Materials and methods. We conducted a prospective multicenter study of the results of surgical treatment of 274 patients with degenerative-dystrophic diseases of the lumbar spine, who underwent monosegmental decompression and stabilization surgery using the TLIF (transforaminal lumbar interbody fusion) technique and open transpedicular rigid fixation, as well as open hemilaminectomy with stabilization of the operated segments with nitinol rods. The study included radiography, diffusion-weighted magnetic resonance imaging and computed tomography (dualenergy mode) of intervertebral discs and isolated facet degeneration of the upper adjacent level.Results and discussion. Combination of the initial proximal segment degeneration in the form of facet joints degeneration (density of cartilaginous plate – 163.5 ± 14.2 HU, density of external facet – 709.35 ± 13.6 HU, density of internal facet – 578.1 ± 12.1 HU), Pfirrmann III, IV grade degeneration of intervertebral disc and a measured diffusion coefficient of less than 1300 mm2/s cause high risks of developing adjacent segment degenerative disease, which regulates the use of monosegmental dynamic fixation with nitinol rods, or preventive rigid fixation of the adjacent segment.Conclusion. Using complex neuroimaging in the preoperative period makes it possible to predict the results of surgical treatment, take timely measures to prevent degenerative diseases of the adjacent segment, and to carry out dynamic monitoring of processes in the structures of the spinal motion segment.

Introduction. According to the literature, the development of adjacent-level syndrome 10 years after posterior rigid stabilization is noted in 6.7–80 % of patients, of which 24 % require revision surgery.The aim: to conduct a comprehensive analysis of the results of surgical treatment of patients with degenerative diseases of the lumbar spine using rigid fixation systems.Materials and methods. A multicenter retrospective study of the results of surgical treatment of 268 patients with degenerative-dystrophic diseases of the lumbar spine, who underwent mono- or bisegmental decompression-stabilizing intervention with the implementation of the TLIF (Transforaminal Lumbar Interbody Fusion) technique and open transpedicular rigid fixation, was conducted. The study included radiography, MRI and CT (in 2-energy mode) of intervertebral discs and isolated facet degeneration of the upper adjacent level.Results and discussion. The combination of the initial degeneration of the adjacent spinal motion segment in the form of disc degeneration of grade III and higher according to Pfirrmann with threshold values of the density of the outer cartilaginous plate from 161.7 ± 18.8 to 164.8 ± 14.2 HU, the density of the outer facet – from 702.43 ± 12.3 to 713.65 ± 13.6 HU and the density of the inner facet – from 580.5 ± 11.6 to 582.1 ± 15.1 HU, as well as with signs of segmental instability of the adjacent segment can be considered as risk factors for the development of its degeneration. With the progression of degeneration of the upper intervertebral disc, revision interventions were performed within 12–60 months after surgery.Conclusion. Bisegmental stabilization with signs of initial degeneration in the intervertebral disc and facet joints in the upper segment has proven its clinical and instrumental effectiveness in the period of 36 months and reduces the risks of developing degenerative disease of the adjacent disc.

Introduction Artificial intelligence (AI) includes software systems combined with applied methods and algorithms which main feature is the ability to solve intellectual problems. One of the most popular trend of AI application is the prognosis of various situations, evaluation of any digital information with an attempt to give a conclusion and analysis of different data with a search for hidden patterns. Study design Systematic review. Purpose To assess current possibilities of artificial intelligence (AI) for predicting unfavorable conditions in spine surgery that require medical care, and future development prospects in this area. Materials and methods Until June 2020 we performed a search using the Protocol (PRISMA) "Preferred Reporting Parameters for Systematic Reviews and Meta-analyzes" and keywords for articles in Medline, Scopus and eLIBRARY intended to summarize the available data on algorithms for predicting any pathological conditions in spine surgery that require medical intervention using artificial intelligence technologies. Results 20 publications were selected for systematic review, which presented data on the application of artificial intelligence, machine learning and neural networks to predict any condition in spine surgery. According to the review, the data obtained indicate that AI can be successfully used to optimize prognosis in various diseases of the spine. Therefore, the application of AI in the clinical practice of the spine surgeons can improve treatment results. Conclusion The promotion of artificial intelligence application in medicine is inevitable. Currently AI shows good results in the area of making clinical decisions by the surgeons and the ability to predict treatment results depending on certain factors. It is imperative that spinal surgeons should realize the potential of these new technologies. Nevertheless, some factors that determine the clinical application of artificial intelligence, i.e. the ability to consider the context of a patient's history, are difficult to calculate mathematically and, so far, are difficult for an algorithmic approach. Eventually, the doctors will continue to play a vital role in patients’ treatment, and artificial intelligence will not depreciate their clinical skills, but make them even more important.

There are various ways to obtain Mo-99. Some of them are widely used in industrial production, others are in the research stage with the aim of increasing the product yield. The main industrial method for obtaining Mo-99 using a nuclear reactor is the fragmentation method. This method provides for the presence of a uranium target and a nuclear reactor. The target is placed in the channel of the reactor core and irradiated with neutrons for the required time. After that, the target is removed from the channel to the “hot” chamber for the chemical separation of Mo-99. This is how Mo-99 is obtained practically all over the world. The paper considers the fragmentation method for producing Mo-99, which is implemented on the basis of the engineering and technological complex of the VVR-c research nuclear reactor. In order to increase the yield of Mo-99, a modernized model of the “tube-in-tube” target is proposed. The assessment of the production of Mo-99 and the cooling efficiency of the modernized target was carried out. The calculations were performed using the VisualBurnOut and Ansys CFX software packages. Computational studies have shown an increase in the energy release and the amount of the produced Mo-99 isotope in the target of the modernized design. In the most stressed zones, the target wall temperature exceeds the water saturation temperature. Surface boiling occurs in these zones. As a result, turbulization and mixing of the near-wall boundary water layer increases. This improves heat dissipation.

Charged-particle trajectories in the MAVR high resolution magnetic spectrometer are simulated. The latter has been constructed at the U400 accelerator for purifying the incident beam and identifying the products of nuclear reactions induced by the beams of stable and radioactive nuclei. In this paper we present the MAVRPC++ software package, aimed at reconstructing the spectrometer focal plane, optimizing the fields of quadrupole and dipole magnets, and estimating the solid-angle acceptance for secondary particles.

Optimizing the use of fuel in a power reactor is a task of current concern. However, little attention has been given to investigating the dependences among the enrichment used, the content of gadolinium oxide in fuel elements, and the life time in combination with assessing the efficiency of using Gd fuel elements with different Gd2O3 contents. The paper considers fuel assembly (FA) versions for VVER-1200 reactors having different enrichments for fuel elements, including those with Gd, and different contents of gadolinium oxide in fuel. A comparative analysis is presented for assemblies with homogeneous Gd2O3 arrangements in each fuel element and with profiled Gd2O3 arrangements. In the latter case, profiling depends on the neutron flux density in the layer which includes Gd fuel elements. This suggests that the arrangement of gadolinium oxide proportionally to the neutron flux density will improve the FA neutronic performance. The results were obtained using SERPENT (a continuous-energy multi-purpose three-dimensional Monte Carlo particle transport code). The assemblies with the used parameters for a 12-month fuel cycle have shown the method under consideration to be inefficient for a period of over 300 eff. days. With increased enrichment and content of gadolinium oxide, the use of profiled versions has turned out to be more rational for longer periods (up to 900 eff. days). Therefore, this phenomenon is relevant for the reactor life, whereas it proves to be insignificant for the fuel life. A complex relationship is noted between the gadolinium and uranium content in an assembly and the effective multiplication factor for the profiled and standard assemblies. This relationship requires further detailed consideration.

Thanks to the successful development of modern medical technologies, the emergence of new knowledge, new instruments and implants, the improvement of surgical techniques, anesthetic support, it became possible to perform surgical correction of spinal deformities in a group of patients suffering from neuromuscular scoliosis, with a lower intraoperative risk, faster recovery and fewer complications. Orthopedic and surgical treatment of paralytic deformities of the spine is carried out using dorsal and ventral techniques by means of correction and polysegmental fixation of the spinal column. As a result of the interventions in this group of patients, the balance of the trunk is improved, the progression of deformity of the spine and chest is prevented, and self-care of patients is improved.

Objective To study morphological and radiological parameters of facet joints depending on the grade of the intervertebral disk degeneration. Materials and methods To study the facet joints of the lumbar spine in 145 patients with various grades of degeneration according to Pfirrmann and treated using rigid fixation and TLIF technology, MSCT in 2-energy mode and morphological investigation of the intraoperative material were performed. Results In Pfirrmann grade 2, an increase in the volumetric content of chondrocytes, Hounsfield density of the cartilage plate, and the level of Ca in the facet joints was visualized. They indicate that the joint remains functional. In Pfirrmann grade 5, deep pathological changes occurred with violation of the architectonics of the cartilage formations of the facet joints, formation of bone elements and connective tissue growth into the cartilage and bone structures of the joint, which correlated with the results of MSCT. Conclusion The data obtained show that there is a close relationship between morphological and radiological changes in the facet joints. Modulating the data obtained allows us to obtain objective criteria for evaluating the grade of pathological processes in facet joints and use them as a diagnostic component when planning decompression and stabilizing operations in patients with degenerative diseases of the lumbar spine.

The choice of an implant for vertebra body defect replacement in corpectomy for traumatic lesions remains a point of discussion among spinal surgeons. Nanostructured carbon cages are promising for use in spinal surgery.The purpose of this study was to determine the rate and degree of cage subsidence in the patients with traumatic lesions of the cervical spine undergone a single-level anterior corpectomy in the subaxial part of the cervical spine with reconstruction using a carbon or titanium cage. Materials and Methods. A prospective study included 47 patients undergone a single-level corpectomy of the cervical spine due to traumatic injury. Two groups were formed by adaptive randomization: group I with the patients with carbon cages (n = 23), and group II with the patients with titanium cages (n = 24). The evaluation of cages subsidence and stability was carried by X-rays and CT before and after surgery. The quality of life before and after the surgery was evaluated using NDI and VAS questionnaires.Results. According to the questionnaires, the absolute majority of the patients in both groups showed a statistically significant improvement of quality of life in the postoperative period (p

Introduction A good alternative to bone autograft fusion is the utilization of implants produced from non-biological materials. Such implants can reduce the duration of surgery as well as tissue morbidity, while meeting the mechanical strength and osteoconductivity requirements. According to the study results, carbon is a promising material for interbody fusion because of its biocompatibility and osseointegration, as well as an elastic modulus that is close to bone tissue. Methods From 2015 to 2017 a randomized multicenter study was conducted. Three centers took part in the study: the National Medical Research Center of Traumatology and Orthopedics named after N.N. Priorov; Novosibirsk Research Institute for Traumatology and Orthopedics named after Ya.L. Tsivyan; Saint-Petersburg National Phtisiopulmonology Research Institute. One hundred thirteen patients with vertebral body fractures were included in the study and underwent surgical treatment using posterior interbody fusion. In 75 patients (66.37 %, group I) carbon-carbon implants were used, and in 38 patients (group II) – titanium cages. Patient examination was conducted using one protocol, preoperative examination methods and at 6, 12, and 24 month follow-ups, and included VAS score, SF-36 questionnaire, and ASIA scale, as well as CT examination and fusion progress assessment according to G. Tan’s classification. Results The 2-year study showed statistically significant differences between index (carbon implants) and control (titanium cages) groups. Although bone fusion progressed very slowly in the study group (in 86 % of cases no bone fusion was observed at first follow-up 6 months after surgery), the VAS and SF-36 scores were comparable in study and control groups. Discussion Carbon implants are characterized not only by high mechanical strength but also by a significant ability to osteoconductivity that allow for effective bone-carbon fusion due to their porous structure and an elastic modulus of 20–30 GPa, that is comparable to that of bone tissue. These characteristics were confirmed by radiological data (absence of implant subsidence in 38 out of 58 patients (65.51 %) at 24 month follow-up. Titanium implants with an elastic modulus of 80 GPa had a subsidence rate of 100 %.

Optimum therapeutic measures aimed at improving the outcomes of patients with neuromuscular spinal deformations against meningocele were developed. Materials and Methods: 8 patients aged 3 to 17 years with neuromuscular spinal deformations against meningocele, surgical treatment was performed one stage — and two-five patients — three patients, two patients underwent resection of the vertebral column (VCR). As a result of correction of scoliosis treatment an average of 62%, the value of thoracic / thoracolumbar kyphosis after surgery could bring to the physiological (40 degrees).

Introduction. Pedicle subtraction osteotomy (PSO) provides for significant segmental correction of the sagittal balance of the spine. At the same time, the technique is associated with a high risk of complications, with rod fracture at the osteotomy site being the most common. The purpose of this study — to assess the effectiveness of four-rod fixation compared to literature data on standard two-rod fixation in patients undergoing PSO. Materials and Methods. The study is a retrospective analysis of 47 consecutive patients with rigid spinal deformities, who underwent pedicle subtraction osteotomy at the lumbar level. The average age of the patients (33 females and 14 males) was 59.7 years. In all cases spinal fixation carried out using a four-rod construct with additional short rods at the osteotomy site. The minimal postoperative follow-up was 2 years. A detailed analysis of the radiographic data was carried out with calculation of the global sagittal balance and spinopelvic parameters. A detailed assessment of complications in the early and late postoperative periods was also performed. After an exhaustive review of literature, a comparative analysis was made of the four-rod fixation technique with current literature data on the frequency of complications (in particular, rod fractures in the osteotomy zone) after two-rod fixation. Results. In all cases the osteotomy was performed at one level, most often at L3 (49%). The average length of fixation was 9.8 segments. The average angle of segmental correction was 27.1°. In most cases, it was possible to achieve adequate correction of spinopelvic parameters. Among complications, bone resorption around screws was most prevalent (23.4% of cases). Proximal junctional kyphosis occurred in 12.8% of cases, neurologic deficit — in 14.9% of cases, infectious complications — in 10.6% cases. Asymptomatic pseudarthrosis, confirmed by CT data, was observed in 12.8% of patients. Rod fracture at the PSO site and adjacent segments was not observed in any of the cases. Rod fractures of other localization were observed in 10.6% of patients. Conclusion. According to the literature, the frequency of rod fractures at the osteotomy site is the most frequent complication of PSO. The results of this study showed that four-rod fixation in PSO significantly reduces the incidence of pseudarthrosis and rod fracture rate in the long-term follow-up and provides greater control over the process of osteotomy closure.

A multidisciplinary approach to treatment of patients with mucopolysaccharidosis allows to achieve good results. However, progressive spinal canal stenosis at the level of the craniovertebral junction, characteristic of this disease, leads to neurological signs, as well as a decrease in quality and length of life. The solution to this problem is a difficult challenge for spinal surgeons, as it is associated with a high risk of complications. There is also a wide range of opinions and approaches to the surgical treatment of this group of patients.Using the referred Reporting Items for Systematic Review and Meta-Analysis» (PRISMA) protocol, a PubMed and eLIBRARY search was conducted using keywords to find articles describing patients with mucopolysaccharidosis who underwent surgical treatment for cervical stenosis. In this review, information on demographic parameters, surgical technique and the results of cervical stenosis treatment in patients with mucopolysaccharidosis is collected and analyzed.

The results of treatment of 72 patients with pathological fracture of vertebra bodies against eosinophilic granuloma a spine are analysed. Orthopedic corset technologies are used in treatment of 42 patients, surgical treatment was applied. Orthopedic corset may be used in patients with eosinophilic granuloma of backbone. This method of treatment was used in a case of the absence of spine secondary deformations and neurologic semiology. Orthopedic corset treatment is associated with long immobilization on the average within 1,5-2 years and never leads to a complete recovery of the damaged spine. Surgical treatment consists in use only at loss of height of a body to 30-40%, when destruction of spine more severe it is necessary to use operative treatment in two stages. Absolute indications to surgical treatment are the neurologic deficit and secondary deformations of a spine. Surgical treatment allows to reduce terms of treatment till 3-4 months and quickly to return the patient to an active life.

Purpose: evaluation of efficacy of operative treatment with the use of screw and hybrid metal constructions in idiopathic scoliosis associated with severe spine deformities. Material and methods: The outcomes of treatment of 34 patients aged 15 to 27 years old with severe scoliosisoperated on using screw metal constructions, were reviewed. 22 patients operated on with the use of hybrid metal constructions, made a control group. The groups were compared by the following parameters: pre- and postoperative Cobb angle, deformity mobility according to traction test, total sagittal/frontal balance, CT apical vertebra rotation, operation time, intraoperative blood loss, the number of instrumented vertebrae, and correction failure at 24-hr spondylograms. Results: Group A (screw spine fixation) demonstrated better outcomes compared to group B (combined spine fixation) in the following parameters. Postoperative correction was 48% and 41%;apical vertebra rotation decreased from 78° to 55° (30%) and from 74° to 59°(21%);total sagittal/frontal balance decreased from 39/25 mmto 14/12 mm (64/52%) and from 35/26 mm to 16/15 mm (55/43%), correspondingly. These results suggest better trunk compensation and postoperative correction in a group of patients with screw fixation. Smaller values of correction failure of the main arc as well as insignificant increase of thoracic kyphosis in the postoperative period (24 months) 3.8%/4.3% in group A compared to 6.2%/7.5% in group B testify to greater reliability and stability of ‘all screw’ metal constructions. The number of fixed elements was on average one more in a group with combined fixation (13 and 14, correspondingly).