Support Ring Research Articles

Modelling of space antenna deployment using open source software

The goal of this article is to develop a dynamic model of a space antenna with the pantograph structure and to study the processes of its deployment using open-source software. Methods of theoretical mechanics, multibody dynamics, computational mechanics, and computer modeling were used in the research. A mesh antenna of the novel design, which is recommended for mini-satellites, is considered as the object for modeling. The most significant difference between this antenna and others is the design of the support ring in the form of a pantograph. To develop a model of the space antenna dynamics and implement it using open-source software, some simplifications were made due to the complexity of the structure. The antenna model is represented as a system of rigid and flexible bodies connected by hinges. Carbon fiber rods are modeled with the help of a flexible finite element using the method of absolute nodal coordinates, which allows one to model large deformations of the structure. Aluminum hinge assemblies are modeled as several rotation joints connected by conventional rigid elements. The main modeled properties of these hinge assemblies are the stiffness, location, and direction of the axes of rotation of the hinges. The tension forces created by the stretched mesh are modeled using springs. The cable drive of the antenna deployment mechanism is modeled as a load acting on the corresponding elements in defined local positions. An algorithm for building a model of the space antenna to simulate the reflector deployment process in the HotInt open-source software is presented. Using the built model, antenna deployment simulations are carried out for different cases, which differ in the forces used for the deployment. Values of deployment time, variations of angles between the V-folded bars, and tensions in the diagonal rods of the antenna sections during the antenna deployment are obtained. The approach proposed in the article can be implemented using free software, ensures flexibility of modeling, and reduces the model development time.

Investigating and Modelling an Engineered Millifluidic In Vitro Oocyte Maturation System Reproducing the Physiological Ovary Environment in the Sheep Model.

In conventional assisted reproductive technologies (ARTs), oocytes are in vitro cultured in static conditions. Instead, dynamic systems could better mimic the physiological in vivo environment. In this study, a millifluidic in vitro oocyte maturation (mIVM) system, in a transparent bioreactor integrated with 3D printed supports, was investigated and modeled thanks to computational fluid dynamic (CFD) and oxygen convection-reaction-diffusion (CRD) models. Cumulus-oocyte complexes (COCs) from slaughtered lambs were cultured for 24 h under static (controls) or dynamic IVM in absence (native) or presence of 3D-printed devices with different shapes and assembly modes, with/without alginate filling. Nuclear chromatin configuration, mitochondria distribution patterns, and activity of in vitro matured oocytes were assessed. The native dynamic mIVM significantly reduced the maturation rate compared to the static group (p < 0.001) and metaphase II (MII) oocytes showed impaired mitochondria distribution (p < 0.05) and activity (p < 0.001). When COCs were included in a combination of concave+ring support, particularly with alginate filling, oocyte maturation and mitochondria pattern were preserved, and bioenergetic/oxidative status was improved (p < 0.05) compared to controls. Results were supported by computational models demonstrating that, in mIVM in biocompatible inserts, COCs were protected from shear stresses while ensuring physiological oxygen diffusion replicating the one occurring in vivo from capillaries.

ASSESSMENT OF STRESS-STRAIN STATE FOR DOME-SHELL OF LUNAR MODULE

Problem statement. Today, the world's leading researchers are engaged in investigating the possibilities of building bases and settlements on the surface of the Moon. To ensure the protection of the crew for long-duration missions, the development of residential modules is required. An effective solution for construction on the Moon is the use of local soil (regolith) for the production of concrete and reinforcement. For today, there are already data on the physical and mechanical properties of such materials, but the studies of the performance for monolithic load-bearing structures made of them are limited. The purpose of the article is to assess the stress-strain state for dome-shells of living modules located on the surface of the Moon, taking into account the physical and mechanical characteristics of building materials from local raw materials (regolith) and environmental conditions. Conclusions. Using the membrane theory’ methods of shells and finite element modeling, data on the stress-strain state of thin-walled shell domes for the construction of lunar living modules for 8, 10, and 12 crew members were obtained. On the basis of the data obtained on internal forces, the required thickness and reinforcement area for the module’ shell were determined. A comparative analysis of the results of determining the internal forces and the structural parameters for the dome-shells considered was carried out. It was established that the deviation of the internal forces values near the support ring in the meridional direction, the internal forces in the area of the dome’ top, as well as the cross-sectional reinforcement area and the shell thickness for all considered options do not exceed 10 %. Exceptions are the data on the internal forces near the support in the ring direction caused by the internal pressure for the 8-crew shell dome, and caused by all types of loads for the 10- and 12-crew variant, which is due to differences in the chosen analysis methods.

Complete Reconstruction of the Left Heart with Atriomegaly and Ventriculomegaly: Clinical Case

Implementation of the principles of medical preparation, comprehensive reconstruction of the left heart in patients with atriomegaly and ventriculomegaly and combined mitral-tricuspid valve diseases leads to improvement of myocardial function and morphometric parameters of the left atrium (LA) and left ventricle (LV).
 Case description. Patient R., male, 67 years old, underwent examination and treatment from April 22 to May 25, 2021 at the department of surgical treatment of acquired heart diseases of the National Amosov Institute of Cardiovascular Surgery of the National Academy of Medical Sciences of Ukraine with the diagnosis of stage IV mitral regurgitation, stage IV tricuspid insufficiency, high grade pulmonary hypertension, permanent atrial fibrillation (lasting 10 years since 2011), IIB heart failure with reduced left ventricular ejection fraction (LVEF), secondary hypothyroidism (state of drug subcompensation). Upon admission, the patient was in a state of circulatory decompensation, which required long-term medical preparation for the operation. After his condition was improved, the patient underwent surgery: mitral valve replacement with complete preservation of the valve apparatus, triangular plasty of LA, tricuspid valve plasty with the imposition of a support ring and resection of the right atrium. There were no complications during the intraoperative period. The postoperative period was characterized by symptoms of hyperbilirubinemia, increased exudation from drainages on the first day after surgery. After appropriate treatment, the patient’s condition was stabilized. The patient was discharged on the 13th day after surgery with improvement.
 Conclusion. Given the initial severe condition of the patient with advanced heart disease with reduced LVEF, left atriomegaly 9.5x12.3 cm, high grade pulmonary hypertension (peak systolic pressure = 70 mm Hg) and comorbidities, comprehensive reconstruction of the left heart with atriomegaly and ventriculomegaly leads to improvement of functional state of the myocardium and morphometric parameters of LA and LV.

Pull-out strength of post-installed connectors in thin UHPC members

Ultra-high-performance concrete (UHPC) has recently been introduced to the precast industry in the form of thin components such as the insulated double wythe precast concrete (DWPC) panels. Existing connectors for conventional DWPC panels may not be applicable for the very thin UHPC-DWPC panels. This paper presents an experimental campaign investigating the behavior and design of screw anchors and a newly designed threaded rod connector embedded in thin UHPC members under pull-out forces. The parameters examined are concrete thickness (tc), connector diameter (d), fiber percentage in UHPC (pf), embedment depth (hef), support ring diameter (ds) of the slab, and concrete compressive strength (f’c). The failure modes consisted of concrete breakout, radial cracking, or a combination of the two. The threaded rod demonstrated better structural performance, with ultimate pull-out loads (Pu) 20 to 50% greater than the screw anchor. Increasing the embedment depth from 0.75tc to 1.0tc (full embedment) increased Pu on average by 19% and 67% for the screw anchor in 25 and 38 mm thick slabs, respectively. Increasing slab thickness from 15 to 38 mm, with 1.0tc embedment, resulted in Pu to be on average over 3.5 and 4 times greater for the screw anchor and threaded rod, respectively. Results showed that connector diameter, fiber percentage, and support ring size did not have significant effect on Pu. Two existing models were evaluated and were found to over-estimate the pull-out capacity based on the parameters of the study. A regression analysis was performed on the data and two new design equations were developed to predict the pull-out capacity of each connector with a high degree of accuracy. A design case study is also presented.

Optimizing structural design on biodegradable magnesium alloy vascular stent for reducing strut thickness and raising radial strength

Thinner biodegradable magnesium alloy stents (BMgSs) afford faster endothelialisation to delay degradation and better clinical performance. However, compared with traditional non-degradable stents, thin-walled BMgS structures are prone to challenges, such as insufficient support capacity and fracture, during immediate expansion due to low elastic modulus and ultimate elongation. In this study, a thin-walled BMgS structure was optimised. A ZE21B alloy with large breaking elongation and excellent mechanical properties served as the basis of our BMgS. Using finite element analysis, the support ring structure of a typical stent BioMatrix was optimised using response surface models, and an optimised configuration of a thin-walled BMgS was obtained. The optimised thin-walled stent (100-μm thick) had a radial strength comparable to that of the original thick-walled stent (150-μm thick); and the maximum principal strain is significantly decreased (0.207 vs 0.283). The balloon dilation and radial strength tests were validated. Experiments showed that the optimised stent had sufficient deformation stability during the crimping and expansion processes, and there was no strut fracture. Furthermore, the maximum principal stress area of the stent and the damage to the stenotic artery were significantly improved after optimisation.

The ribbed-annular dome's upper tier model stability experimental studies

Abstract. Purpose. The work’s aim is to check the stability loss hypothesis with the snap-through effect of the ribbed-annular dome's upper tier on a full-scale model by experimental tests, and confirming the nonlinear tier's work under external load. Methodology. The ribbed-ring dome circumscribe in the plan as a circle with a diameter of 18 m with the dome rise ratio to the span - 1/4, which consisted of 8 ribs and had 6 tiers in height, was taken as an dome-model analog.The upper tier of the dome is bounded by the lower ring, which is the upper ring for the tier below, and the dome's upper support ring.Tier rings and ribs are made of steel closed bent welded profiles with rectangular cross section. As a dome's upper tier model, it was decided to use the von-Mises truss as a popular model for two-rod inclined systems' theoretical stability studies, which allows modeling these systems nonlinear behavior. The classic von-Mises truss using in modeling the dome's upper tier behavior is associated with a number of problems.First, the tier is a three-dimensional system with eight rods, so it was decided to model the tier with an equivalent low-pitched truss, which is 1/4 of the upper tier.Secondly, the lower tier ring has limited rigidity and can be deformed, while the classic truss has fixed supports, which is why it was decided to add elastic horizontal supports to the classic von-Mises truss model.Horizontal elastic supports were performed as steel pair puffs and were simulated the dome's upper tier lower support ring deformations. Findings. The obtained data primary and secondary processing, and the full-scale experiment results analysis were carried out. The ribbed-annular dome's upper tier nonlinear deformations nature under the external concentrated vertical load action in the ridge node was confirmed.It was established that in the ridge joint the upper tier's stability loss nature has the snap-through effect. Scientific innovation. The deformation dependencies for the equivalent von-Mises truss with elastic supports with the help of full-scale experimentwere obtained. A comparison of the equivalent truss' behavior experimental studies results with the existing theoretical studies' results was made. The experimental and theoretical studies results analysis confirmed the experimental data results reliability and analytical expressions feasibility use for the preliminary assessment of von-Mises truss' with elastic supports stability. Practical value. The obtained results of experimental research allow creating tools for designers to increase the dome structures reliability.

The free vibration analysis of carbon nanotubes-reinforced deep conical shells with an intermediate ring support under various boundary conditions

This article explores the free vibration characteristics of a conical shell strengthened with intermediate ring. The system is thought to be made up of a linearly elastic nanocomposite that is reinforced with carbon nanotubes (CNTs). To get the effective material characteristics, the modified rule of mixtures is employed. To account for shear deformations and rotational inertias occurring across the depth of the shell, the first-order model of shells is combined with Donnell’s classical kinematic constraints. Hamilton’s principle is applied to construct the generic motion equations and their related boundary and compatibility constraints. The resulting set of equations is solved analytically in the structure’s circumferential direction. Additionally, the generalized differential quadrature element (GDQE) algorithm is performed to discretize the radial motion equations. An eigenvalue issue is constructed with various edge conditions for the structure boundaries and compatibility conditions to investigate the vibration frequencies. After demonstrating the efficacy and accuracy of the current approach for applying functionally graded (FG) CNT reinforced composite (RC) cylindrical shells with intermediate circle support, several parametric investigations are conducted to determine the effect of the geometric and ingredient properties of FG-CNTRC conical shells.

RESEARCH OF INCREASING THE CAPACITY OF THE MAIN ELEMENTS OF A SUBMERSIBLE CENTRIFUGAL ELECTRIC PUMP DEVICE

The article is devoted to the investigation of the causes of failures in centrifugal submersible electric pumping units (CSEP) during the work process, the measures taken to eliminate failures, improve performance and increase the time between repairs. In order to improve the performance of CSEP, a number of changes were made in the design. Keywords: centrifugal submersible electric pumping unit, guidance apparatus, impeller, support ring, friction.

Transosseous Multiple Finger Flexor Tendon Pulley Reconstruction

Background: Closed finger flexor tendon pulley injuries occur most frequently in rock climbing but also during other heavy finger strength work or exercises. While single pulley injuries receive a conservative therapy, multiple pulley injuries often require a surgical repair, as otherwise they will lead to contracture and loss of range of motion and functionality. While established surgical techniques, which use bone encircling tendon graft techniques, were found to produce osteonecrosis of the phalanx, our new transosseous technique avoids this problem. Indications: All triple pulley injuries (A2,3,4) (grade-4b injuries) and double pulley injuries (A2,3 or A3,4) (grade-4a injuries) are indicated, if the injury is older than 10 days at the point of therapy start or the flexor tendons bowstringing is either not redressable in the ultrasound or extended. Also, grade-4a injuries are indicated, if a secondary contracture starts to build. Technique Description: Standard palmar-sided incision, followed by debridement of the tendon sheath, pulley flap, and, if applicable, scare tissue in between the flexor tendons and the bone is performed. Wire-guided 3.0-mm drill holes at the base phalanx at the level of the former distal portion of the A2 pulley are completed. Passing of the palmaris longus tendon through the drill hole and interlacing it as a “loop and a half” follows. Distal continuation through lacing the transplant through the remaining rims of the former pulleys and the flexor tendon sheath is then performed. Securing the repair after tendon gliding control to itself is completed. Postsurgically, the splint is immobilized for 2 weeks, followed by the use of a thermoplastic pulley support ring for 4 weeks with active mobilization. Results: No complications occurred during or after the surgery. In few cases, a restricted range of motion in the proximal interphalangeal (PIP) joint of the respective finger of up to 3 to 5 grade occurred. One patient, who had a presurgical PIP extension deficit of 30°, which was released during the surgery, developed over time again a 20° extension deficit. The functional outcome score ranged between good and excellent, with one case being only satisfactory. The sport-specific outcome score was either good or excellent for all patients, with one patient with contracture where it was satisfactory. No osteonecrosis of the phalanx was recorded. Discussion: For multiple pulley ruptures, various surgical techniques are described. We favored a modified “loop and a half” technique with a distal continuation to the A3 pulley. This combines the advantages of the “loop and a half” technique, as the strongest, and the Weilby repair, as the most functional repair. We recently noticed some cases with osseous necrosis of the phalanx following this repair, likely due to the high pressure of the circulation of the tendon graft onto the bone and its blood vessels. Therefore, we have modified our procedure into a transosseous repair, which is presented in this article. This approach was first evaluated in a cadaver study to exclude a potential risk of osseous failure (fracture) during stress caused by the drill hole. After ruling out this risk, the transosseous technique became our standard approach, as it combines the advantages of the “loop and a half” technique with those of the Weilby repair and decreases the pressure onto the dorsal cortex of the fingers base phalanx and thus the risk of osteonecrosis.

PERFORMANCE EVALUATION OF PARABOLIC CONCENTRATOR WITH THERMAL STORAGE SYSTEM FOR DOMESTIC APPLICATIONS

Solar energy is a free natural resource but its harvesting requires a high capital investment whichprohibits its maximum exploitation. A Parabolic Dish Solar Collector (PDSC) with a thermalstorage system was been constructed and developed to harness solar beam radiation. The thermalstorage system and PDSC were constructed using locally and less cost materials such asgalvanized metal sheet and steel rods curved to obey the equation of a parabola then weldedtogether with circular support rings which was then lined with stainless steel reflector pasted forthe construction of PDSC. The receiver was made of blackened aluminium material incorporatedwith coiled copper tube carrying water as the heat transfer fluid. A parabolic dish which acts of aheat collector is used to track and reflects solar radiation at a single point (focus) on a receiverabsorber. Heat transfer from the solar collector to the storage tank was done by usingthermosyphonic principle to circulate the water (heat transfer fluid) between storage tank andheating system (receiver). The evaluation of thermal storage and analyzing the efficiency oftracking and non-tracking parabolic dish solar collector was carried out during month of June,2020 for the composite climate of Sokoto. According to the finding, the efficiency of trackingPDSC with thermal storage system and non- tracking PDSC with thermal storage tank weredetermined and obtained to be 52.9% and 50% respectively.Keywords: thermal efficiency, parabolic dish collector, solar radiation, storage system andstainless steel reflector.

ЕXPERIENCE OF LONG-TERM APPLICATION OF PERCUTANEOUS ENDOSCOPIC MICROGASTROSTOMY AS A METHOD OF ENTERIAL AND THERAPEUTIC PROVISION OF PATIENTS

Purpose. Analysis of surgical aspects of the experience of 13 years of percutaneous endoscopic microgastrostomy for enteral therapeutic provision of patients with parkinsonism.Methods. The 4-year follow-up group (2012-2021) included 20 patients aged 55 to 72 years with severe Parkinson's disease, mostly men. From 2008 to 2012, patients underwent microgastrostomy installation using a Frezenius kit. Levodopa carbidopa was injected into the jejunum through a micro-drainage gastrostomy.Results. During the 1st year of gastrostomy functioning, the following complications developed: gastric juice leakage onto the skin with the skin maceration development (2 cases), the hypergranulation development around the gastrostomy (3 cases), the gastrostomy support ring prolapse into subcutaneous fat with an abscess development (2 patients). By the end of the 4th year follow-up, 3 more patients had gastrostomy prolapse into subcutaneous tissue without suppuration. On the micro-drainage part complications were observed in the form of the bezoar formation at the tube end and micro-drainage nodulation in the stomach with the lumen obturation. The author used different methods of prevention and complications treatment in each individual case. To prevent gastric juice leakage and the proliferation of hypergranulations, tube fixation correction and local treatment are necessary; to prevent prolapse of the gastrostomy support ring, it is advisable to use a prolene mesh gasket. A gastrostomy change l with proper care is advisable 1 time in 3-4 years, micro-drainage at least 1 time in 2 years to prevent the bezoar formation on the catheter and its rupture.Conclusion. Puncture microgastrostomy performed under endoscopic control can be effectively used for a long time to inject nutritional mixtures and medicines into the gastrointestinal tract.

The Effect of Intermediate Ring Support on the Vibration Behavior of Functionally Graded Conical Shells

In this study, the free vibrational behavior of a thin-walled functionally graded conical shell with intermediate ring support is investigated. Theoretical formulations were established based on the first-order shear deformation theory. The governing equations of motion were solved using the Galerkin method. Applying a set of displacement functions, the equations of motion result in an eigenvalue problem, by solving which, the natural frequencies of vibration are determined. Material properties are assumed to be varied in the thickness direction according to the power-law volume fraction function. It has been attempted to examine the effects of ring support position on the natural frequencies of vibration and to introduce the optimal scenarios of the support placement to achieve a higher frequency. In addition, a 3D FE model was built in the ABAQUS CAE software in order to validate the results of the analytical model. The analytical results were in close agreement with the literature and also the numerical ones. Moreover, the effects of some commonly used end conditions, variations in the shell geometrical parameters, changes in the ring support placement have been investigated on the vibrational behavior.

VIRIAL THEOREM LIMITATIONS FOR THE TOROIDAL MAGNETIC ENERGY STORAGE CAUSED BY THE LOCATION OF SUPPORT STRUCTURE ELEMENTS AND THEIR MECHANICAL PROPERTIES

Based on the virial theorem, the influence of the following factors to characteristics of mechanical support systems of toroidal magnetic energy storage is considered: the configuration of the coils, the support system elements location under compressive forces, the mechanical properties of the material, the distribution of the cross-sectional areas of the support rings and the corresponding distribution of radial forces. It is established that the volume of structure requirement depends only on the radii from which the coils transmit forces to the support rings. The found general relation, in contrast to the existing ones, establishes a relationship between all the parameters that determine the volume of the support structures. The characteristics of support systems are analyzed both for identical mechanical stresses and for identical mechanical properties of all support elements. The characteristics for specific examples of toroidal systems with circular coils are found. It is shown that systems with support elements in compression located on the side of the vertical axis of the torus have a significantly smaller volume of structure compared to other locations. The influence of the relative radial size of the torus cross-section and the distribution of the cross-sectional areas of the support rings on the structure requirement is analyzed. The relationship between dimensionless characteristics that determine the volume of elements subjected to mechanical stresses of compression and tension is noted. References 37, figures 8, table 1.

A biodegradable magnesium alloy vascular stent structure: Design, optimisation and evaluation

The existing biodegradable magnesium alloy stent (BMgS) structure is prone to problems, such as insufficient support capacity and early fracture at areas of concentrated stress. Herein, a stent structural design, which reduced the cross section of the traditional sin-wave stent by nearly 30% and introduces a regular arc structure in the middle of the support ring. The influence of the dual-parameter design of bending radius (r) and ring length (L) on plastic deformation, expansion and compression resistance performances are discussed. The non-dominated sorting genetic algorithm II (NSGA-II) was used to search for the optimal solution. It was found that the introduction of parameter r effectively improved the plastic deformation and expansion performance, and the reduction of L improved stent compression resistance. Finally, an optimized stent configuration was obtained. In vitro mechanical tests, including balloon inflation, radial strength and flexibility, verified the simulation results. The radial strength for the optimised stent increases by approximately 40% compared with that for the sinusoidal stent. Microarea X-ray diffraction result shows that the circumferential residual stress for the optimised stent decreases by half compared with that for the sinusoidal stent, thus effectively reducing the stress concentration phenomenon. Statement of significanceDespite current progress in BMgS research, the optimal design of the structure is limited. We present a new type of structurally designed stent. The performance of this stent was analysed by a finite element method and experimentally verified. The structural design positively influenced stent performance.

Evolution of excavation-induced critical stress ring and corresponding support of deep roadway

Evolution of excavation-induced critical stress ring and corresponding support of deep roadway

Study on low flow resistance ventilation hose with rapid retraction in space cabin

Aiming at the required of high air tightness, low flow resistance, rapid expansion, easy operation on orbit and hygiene in the space cabin, a low flow resistance ventilation hose which can be retracted quickly in the cabin is proposed. The ventilation hose is composed of metal support ring, air tight composite material, quick connection connector and clamp. After sewing the adhesive tape into a cylindrical tube, it is hot-melt welded with the titanium ring. The pipe body and the quick connection joint are connected and fixed by clamps. After structural design and test verification, a hose with an extension length of 10 meters can shrink to 0.42 meters. the air tightness is 0.96 L/min and the flow resistance is 120Pa. The ventilation hose has the advantages of reliable technology, compact structure, light weight and convenient use in orbit. It provides a new technical way and equipment for the ventilation system in manned spacecraft.

Surgical management of biatrial myxoma: case report

Heart tumours account for approximately 0.2 % of all tumours: of these, approximately 75 % of all primary heart tumours are benign and 50 % of them are myxomas. Further, myxomas make up 0.0017 % of the general population of patients with cardiovascular disease. Biatrial myxomas, i.e. tumours in both the left and right atria, can be in the form of a ‘butterfly’ or a ‘dumbbell’, and account for < 1 % of all cardiac myxomas. Here we describe the successful surgical management of a rare case of a large biatrial myxoma and concomitant atrioventricular valve insufficiency. Briefly, 2D transthoracic echocardiography findings included an end-diastolic volume of 90 ml, an end-systolic volume of 40 ml and a left ventricular ejection fraction of 55 % (according to Simpson). The fibrous ring of the mitral valve measured 36 mm with a regurgitation degree of 2 while the fibrous ring of the tricuspid valve was 42 mm in size and the regurgitation grade was 3. Lesion size in the cavity of the left and right atrium were 73 × 38 mm and 80 × 42 mm, respectively. These neoplasia were surgically removed under peripheral cardiopulmonary bypass, hypothermia and cold cardioplegia (Custodiol). The myxomas were accessed through the right atrium, according to Giradon and were resected without defragmentation. Next, mitral valve plasty using a soft support ring and annuloplasty of the tricuspid valve were performed according to de Vega. The duration of artificial circulation was 150 minutes and that of myocardial ischaemia was 100 minutes. The patient was extubated 11 hours after surgery, spent 22 hours in the intensive care unit and was discharged on the 14th day after surgery. Surgical resection of biatrial myxomas before the development of serious irreversible or life-threatening complications can provide rapid symptomatic relief in congestive heart failure.Received 30 May 2021. Revised 22 August 2021. Accepted 23 August 2021.Funding: The study did not have sponsorship.Conflict of interest: Authors declare no conflict of interest.Contribution of the authors Literature review: T.A. Simonyan Drafting the article: T.A. Simonyan, I.M. Tsiskaridze Critical revision of the article: T.A. Simonyan, I.Yu. Farulova, E.A. Babajanyan Surgical treatment: I.I. Scopin, I.M. Tsiskaridze Final approval of the version to be published: T.A. Simonyan, I.I. Scopin, I.M. Tsiskaridze, I.Yu. Farulova, E.A. Babajanyan

Immediate clinical results of the new biological support ring for correction of mitral insufficiency

Aim. To make the first clinical experience evaluation of the new biological closed support ring for mitral valve.Methods. 26 patients (16 men, 10 women, mean age 55 [49; 62] years) with dysplastic mitral insufficiency were implanted “NEORING” biological ring for the first time from March 2020 to June 2021. The etiological factor of the defect formation in all cases was the connective tissue dysplasia. The mean functional class of heart failure before surgery was 2 [2; 3] according to NYHA, the effective regurgitant orifice (ERO) was 0.4 [0.3; 0.5], vena contracta was 0.7 [0.6; 0.8]. Ten patients received rings of 28 mm diameter, ten patients – 30 mm, six patients – 32 mm.Results. No significant adverse events such as death from any causes, strokes, myocardial infarction, cardiac complications, bleeding, and return of regurgitation or failure of plastic surgery requiring reoperation, infective endocarditis after the intervention were observed. In two cases a permanent pacemaker was implanted due to sinus node dysfunction. At discharge all patients had no regurgitation (ERO 0), medium transvalvular gradient was 4.0 [3.0; 5.3] mm Hg. All the patients were assigned to NYHA functional class I heart failure after the surgery.Conclusion. New biological support ring “NEORING” (“NeoKor”, Kemerovo) use in the middle age group of patients showed high hemodynamic efficiency, the absence of specific complications in the early stages after the surgery. It is planned to expand the clinical material on the use of the biological ring, as well as to evaluate the long-term results in the format of a prospective, randomized trial and compare the new device with the existing ones.

Repositional-fixation ring for surgical treatment of acetabular fractures (preliminary results of static tests)

BACKGROUND: Currently, several types of designs of support rings of M. Muller, Burch-Schneider, rings of the company Protek (Switzerland), implanted in the BB are widely used, which are used in the surgical treatment of long-standing fractures of the BB, as a rule, as a device that strengthens the walls of the BB.
 AIM: Study of the deformation properties of the repositional-fixing ring.
 MATERIALS AND METHODS: For carrying out mechanical tests, a ring with an external diameter of 52 mm was made by the method of sequential sintering using additive technologies by the company Konmet LLC, Moscow. Laboratory mechanical tests were carried out by the Testing Laboratory of Medical Devices and Materials of the N.N. Priorov National Medical Research Center of Traumatology and Orthopedics.
 RESULTS: As a result of static testing of the ring for compression, tension, torsion, and joint stretching and twisting of the edges of the ring connector, its deformation properties are studied. Load corresponding to the deformation of 2 mm, kN: compression 0.180; tension 0.061; torsion (torque corresponding to the angle of rotation of 5 degrees, Nm) 2.653; joint tension with twisting of the edges of the ring connector (load corresponding to the deformation of 10 mm, kN) 0.048.
 CONCLUSION: The results of the initial study of the deformation behavior of the ring structure show that it is necessary to refine the ring design and further study the deformation and strength characteristics of the ring.