Valve Surface Research Articles

Study on Hydrodynamic Lubrication and Friction Reduction Performance of Cylindrical Rolls With Tesla Valve Texture

Friction and wear seriously affect the efficiency and life of a machine device. The dynamic pressure lubrication and friction properties of the surface are improved by surface texture technology, which plays an extremely important role in reducing friction and wear. In order to maximize the hydrodynamic lubrication and friction reduction performance of surface texture, a Tesla valve surface texture is proposed in this article. The oil film bearing capacity and wall friction of Tesla valve texture are examined through computational fluid dynamics fluid simulation. Cylindrical rolls with Tesla valve texture are prepared by using laser processing technology, and comparative friction wear tests are conducted. The results show that the lubrication performance of Tesla valve texture is four times higher than without this texture. The friction coefficient and wear loss of the cylindrical rolls with Tesla valve texture are, respectively, 39.7% and 66.7% lower than those of the cylindrical rolls without texture. Tesla valve texture effectively improves the dynamic pressure lubrication and friction in the cylindrical rolls.

Theoretical Analysis and Numerical Simulation of the Wear of the Sealing Substrate of a High-Pressure, High-Frequency Opening and Closing Hydrogen Ball Valve.

High-pressure valves are an essential infrastructure for hydrogen refueling stations, and the issue of safety and reliability of their operation affects the efficiency of the entire hydrogen delivery system. Hydrogen ball valves are subjected to high-frequency, rapid reciprocating opening and closing for a long time, and the sealing surface between the valve seat and the ball has an uneven wear distribution problem. In this paper, a theoretical derivation of the seat wear volume and wear depth during the hydrogen ball valve adhesive wear process is presented, and a simulation model based on transient dynamics theory is established to carry out a nonlinear finite element analysis of the dynamic contact and frictional wear of the sealing structure during the opening and closing process of the hydrogen ball valve. In order to effectively reduce the wear unevenness of the sealing surface of the ball valve, a new type of valve seat sealing surface with an unequal-width structure is proposed. Comparing the sealing pressure and seat sealing surface wear depth of the ball valve before and after the improvement, the improved ball valve sealing performance is reliable, while the seat sealing surface wear distribution is more uniform.

Borers and epizoans on oyster shells from the upper Tortonian, Lower Chelif Basin, NW Algeria

The three oyster lenses of the upper Tortonian of Djebel Touaka site which are described herein contain three species, Crassostrea gryphoides (Schlotheim), Ostrea lamellosa (Brocchi) and Hyotissa squarrosa (De Serre). The density of shell packing between the lenses is dissimilar. Most of the specimens are disarticulated and poorly fragmented; they exhibit a random distribution and orientation, without any distinct sorting. Bioerosion and encrustation are featured on both surfaces of left and right valves. The identified ichnogenera are Entobia (Bronn), Gastrochaenolites (Leymarie, 1842), Caulostrepsis (Clarke, 1908), Trypanites (Mägdefrau, 1932) and Maeandropolydora (Voigt, 1965). Encrusters are scared, represented by juvenile oysters/other bivalves, bryozoans and barnacles. The coexistence of borings on both sides of valves means that they probably occur not only while alive, but they keep happening after death. The oyster beds were deposited in a foreshore to shoreface environment, from the combined action of wave currents and sedimentation rate.

First record of the trace fossil Renichnus arcuatus Mayoral, 1987 in the Pliocene of Sidi Brahim (Lower Chelif Basin, NW Algeria)

A vermetid etching trace, Renichnus arcuatus, has been described from the outer surface of a single right valve of Hyotissa hyotis from the Lower Chelif Basin, Algeria. This is the first record of vermetid etchings from the Pliocene of the Mediterranean Sea's southern coast. The vermetids responsible for the etchings used bivalve shells as a hard substrate for attachment. The vermetids used mucus nets to feed and they may have benefitted from the feeding currents of the host if they colonized a living bivalve. The palaeogeography of similar etching records indicates that vermetids were common in the Mediterranean region in the Pliocene.

Assessing The Predictive Value Of Calcified And Non-calcified Aortic Valve Volumes And Surface Areas For Aortic Stenosis Severity

Assessing The Predictive Value Of Calcified And Non-calcified Aortic Valve Volumes And Surface Areas For Aortic Stenosis Severity

Riding up the escaLEC-TOR for valvular health.

Endothelial-lined valves assure unidirectional flow in the lymphatic system. In this issue, Saygili Demir et al. (2023. J. Cell Biol.https://doi.org/10.1083/jcb.202207049) demonstrate how continuous repair of these valves occur, beginning with mTOR-activated cell replication in valve sinuses, and followed by cell migration to cover the valve surface.

Bioprosthetic Valve Deterioration: Accumulation of Circulating Proteins and Macrophages in the Valve Interstitium

Histologic evaluations revealed excessive accumulations of macrophages and absence of fibroblastic interstitial cells in explanted bioprosthetic valves. Comprehensive gene and protein expression analysis and histology unveiled an accumulation of fibrinogen and plasminogen, an activator of infiltrated macrophages, from degenerated valve surfaces in the interstitial spaces. These pathologies were completely reproduced in a goat model replaced with an autologous pericardium-derived aortic valve. Further preclinical animal experiments using goats demonstrated that preventing infiltration of macrophages and circulating proteins by increasing collagen density and leaflet strength is an effective treatment option.

Histopathology of the Mitral Valve Residual Leaflet in Obstructive Hypertrophic Cardiomyopathy

BackgroundMitral valve (MV) elongation is a primary hypertrophic cardiomyopathy (HCM) phenotype and contributes to obstruction. The residual MV leaflet that protrudes past the coaptation point is especially susceptible to flow-drag and systolic anterior motion. Histopathological features of MVs in obstructive hypertrophic cardiomyopathy (OHCM), and of residual leaflets specifically, are unknown. ObjectivesThe purpose of this study was to characterize gross, structural, and cellular histopathologic features of MV residual leaflets in OHCM. On a cellular-level, we assessed for developmental dysregulation of epicardium-derived cell (EPDC) differentiation, adaptive endocardial-to-mesenchymal transition and valvular interstitial cell proliferation, and genetically-driven persistence of cardiomyocytes in the valve. MethodsStructural and immunohistochemical staining were performed on 22 residual leaflets excised as ancillary procedures during myectomy, and compared with 11 control leaflets from deceased patients with normal hearts. Structural components were assessed with hematoxylin and eosin, trichrome, and elastic stains. We stained for EPDCs, EPDC paracrine signaling, valvular interstitial cells, endocardial-to-mesenchymal transition, and cardiomyocytes. ResultsThe residual leaflet was always at A2 segment and attached by slack, elongated and curlicued, myxoid chords. MV residual leaflets in OHCM were structurally disorganized, with expanded spongiosa and increased, fragmented elastic fibers compared with control leading edges. The internal collagenous fibrosa was attenuated and there was collagenous tissue overlying valve surfaces in HCM, with an overall trend toward decreased leaflet thickness (1.09 vs 1.47 mm, P = 0.08). No markers of primary cellular processes were identified. ConclusionsMV residual leaflets in HCM were characterized by histologic findings that were likely secondary to chronic hemodynamic stress and may further increase susceptibility to systolic anterior motion.

Effect of Compressed Natural Gas (CNG) on corrosion behaviour of brass valve of CNG cylinder

In this case study, failure root cause analysis of the Compressed Natural Gas (CNG) cylinder brass valve was investigated. Detailed metallurgical analysis of the cracked CNG valve was performed. Higher content of sulphur and carbon while depletion of zinc observed by Scanning Electron Microscope (SEM) - Energy Dispersive Spectroscopy (EDS) analysis at crack location and on black corrosion product. Microstructure analysis of the cross section near to fracture surface indicated dendritic structure of alpha and beta phase and depletion of zinc from beta phase at the inner diameter (ID) of valve and near to crack region by SEM-EDS analysis. The overall observation indicates that the failure of brass valve body of CNG cylinder was due to the dezincification. As per the IS 15958 standard, the CNG valves, which have failed, may be due to more than specified limit of the corrosive components (S and CO2) in the CNG. This resulted into diffusion of sulphur and carbon dioxide in beta phase at internal surface of valve. Adsorbed sulphur and CO2 from the CNG lead to the preferential dezincification from beta phase throughout the inner diameter (ID) of the valve. Electrochemical reaction during dezincification lead to weak spongy copper layer, which subsequently initiated and propagated crack to the outer diameter (OD) and resulted into leakage and failure.

Achnanthidium lucectorii sp. nov. and A. enigmaticum sp. nov., novel diatoms (Bacillariophyta, Achnanthidiaceae) from Texas, U.S.A.

Two new species, Achnanthidium lucectorii sp. nov., belonging to the A. minutissimum complex (species with straight terminal raphe ends), and A. enigmaticum sp. nov., within the A. pyrenaicum complex (species with hooked terminal raphe fissures), are described from Texas, U.S.A. utilizing light and scanning electron microscopy. Achnanthidium lucectorii sp. nov. has a raphe valve with striae located toward the apices composed of polygonal areolae, a marked stauros, a non-expanded raphe fissure, with straight (non-dilated) proximal ends, and distal ends extending onto the valve mantle. Internally, its raphe valve is flat, the proximal ends of the raphe end in small capitate expansions, and the distal ends terminate in low helictoglossae that fuse with the apices by a low apical siliceous thickening. In turn, its sternum valve is unique in that it is mostly flat in inner view, except at the central nodule, which is slightly raised. In turn, A. enigmaticum sp. nov. externally has a raphe valve with raphe distal ends shaped like a closed hook, at these ends the raphe slit surfaces at the valve face/mantle junction; its axial area is raised in external and internal views, with the virgae and striae in a lower position. These and other traditionally considered features are compared in detail with taxa morphologically similar to each of the new species. The significance of these features is discussed based on a literature survey, and the implications of considering the valve surface topography and the external and internal details of the raphe and central area are assessed. The latter, in favor of a continued morphological exploration of Achnanthidium until molecular studies are appropriately integrated into current morphological approaches used in the taxonomy of the genus.

Plug Valve Surface Defects Identification through Nondestructive Testing and Fuzzy Deep-Learning Algorithm for Metal Porosity and Surface Evaluation

This paper addresses the detection and identification of flaws in Plug valves. The Plug valve thermal image is acquired using a Fluke thermal camera [TiS20]. Thermal images of the Plug valve are used for the identification of flaws such as Crack, Porosity, Corrosion, and Internal defects. The thermal images detect the surface flaws and never subsurface flaws in Plug valves. The subsurface flaws detection is a challenging problem in valve inspection. In this paper, the thermal images obtained after the dye penetrates the surface valve detect the surface flaws more efficiently after applying the Fuzzy Deep Learning Algorithms. DyePenetrating Test (DPT) combined with Infrared Thermography is proposed to identify heat flux changes and flaws in the faulty metal surface of Plug valves. In DPT, thinned paint is employed on the metal surface that displays metal porosity and even fine cracks. After DPT, thermal images of the Plug valve are processed through the Fuzzy Deep Learning Algorithm to evaluate flaws. The Fuzzy Algorithm is utilized prior to Deep Learning to simplify and speed up the classification task. The flaws are identified using Slicing operation and the following parametric quantities such as Accuracy, Mathew’s Correlation Coefficient (MCC), Local Self-Similarity Descriptor (LSS), Precision/Recall, F-measure, and Jaccard Index. The parametric quantities depict corresponding variations with regard to surface coarseness and metal flaws. The DPT and Fuzzy Deep Learning Algorithm identify metal defects with 80.67% accuracy.

Initial Clinical Experience and Biomechanical Analysis of a Novel Gravity Unit-Assisted Valve (M.blue) in Pediatric Patients With Hydrocephalus: A Retrospective Study With Two Years of Follow-up.

Overdrainage is a widely reported complication representing common indication for shunt revision. Despite recent advances in valve design, repeated shunt revisions represent burden on healthcare systems. To investigate the efficiency of a novel gravity unit-assisted programmable valve "M.blue" in pediatric hydrocephalus using clinical and biomechanical analyses. Thisretrospective single-center study included pediatric patients who received M.blue valve between April 2019 and 2021. Several clinical and biomechanical parameters were documented including complications and revision rates. Flow rate, functional assessment in vertical and horizontal positions, and extent of depositions inside valve were analyzed in explanted valves. Thirty-seven M.blue valves in 34 pediatric patients with hydrocephalus (mean age 2.82 ± 3.91 years) were included. Twelve valves (32.4%) were explanted during a follow-up period of 27.3 ± 7.9 months. One-year survival rate of 89% and overall survival rate of 67.6% with a valve survival average of 23.8 ± 9.7 months were observed. Patients with explanted valves (n = 12) were significantly younger, with 0.91 ± 0.54 years of age in average ( P = .004), and showed significantly more adjustments difficulties ( P = .009 ). 58.3% of explanted valves showed deposits in more than 75% of the valve surface despite normal cerebrospinal fluid findings and were associated with dysfunctional flow rate in vertical, horizontal, or both positions. The novel M.blue valve with integrated gravity unit is efficient in pediatric hydrocephalus with comparable survival rate. Deposits inside valves could affect its flow rate in different body positions and might lead to dysfunction or difficulties in valve adjustments.

Advances in diagnosis and treatment of mechanical hemolysis following percutaneous interventional for valvular heart diseases.

Valvular heart disease is one of the common heart diseases in clinical practice, characterized by valve stenosis and/or incomplete closure. At present, drug therapy, surgery, and emerging percutaneous intervention therapy are the main treating methods for heart valve disease. Although the research and development of percutaneous intervention therapy devices is relatively mature, there are still problems such as postoperative mechanical hemolysis. The occurrence of mechanical hemolysis is associated with factors such as excessive shear stress experienced by red blood cells, direct interaction between red blood cells and the heart and valve surfaces, and thrombus formation. Furthermore, the presence of postoperative infection and other hemolytic diseases can also affect the occurrence of mechanical hemolysis. Although most patients are asymptomatic when hemolysis occurs, there are still critical cases. This type of hemolysis can accelerate the deterioration of the condition, and even endanger life in severe cases. Therefore, elucidating the background, pathogenesis, epidemiology, and related clinical research progress of mechanical hemolysis after percutaneous intervention therapy for valvular heart disease is of great significance for guiding the standardized diagnosis and treatment of the disease.

Construction of superhydrophobic pyrolytic carbon by creating a biomimetic cobblestone surface pattern for improved hemocompatibility

Although pyrolytic carbon (PyC) has been extensively used in mechanical heart valves, subsequent thrombus formation threatens patient survival. An effective solution to obtain antithrombotic PyC is to endow the PyC surface with superhydrophobicity. Inspired by native heart valve surface patterns, we for the first time, generated a biomimetic cobblestone pattern on the PyC substrate via laser ablation. For comparison, two other patterns of grating and mastoid were also created. The patterned surface was further modified with fluorosilane to achieve superhydrophobicity. The influence of pattern geometry on wettability, drag reduction, and hemocompatibility were studied. Although the three superhydrophobic PyC surfaces exhibited comparable roughness and superhydrophobicity, the cobblestone patterned PyC surface exhibited fewer adhered platelets and longer thrombin time than others. Our results suggest that the biomimetic cobblestone pattern on PyC offers a promising method of improving the hemocompatibility of PyC heart valves.

Novel wavy surface design for enhanced frame anchoring performance in the exchangeable transcatheter aortic valve implantation procedure

Laser powder bed fusion, LPBF, provides manufacturing advantages, not only for complex geometry, but also for small-scale surface features. In this study, the benefit of introducing a wavy feature on the surfaces of replacement heart valves has been explored. Specifically, a new concept in exchangeable valves aims to implant a holding frame into a diseased valve such that an exchangeable valve can be implanted into the holding frame but can then be removed and replaced by another exchangeable valve as and when the first valve deteriorates. In this proposed procedure, the anchoring force between the holding frame and valve frame could be too low to prevent the valve from displacing as blood is pumped through the heart. One way in which the anchoring force could be increased is by introducing a wavy profile on the contact surfaces between the frames. In this study, a flat representation of the two frames has been used to computationally investigate the effect of wavy surface profiles on the force required to displace one frame relative to the other. The so-called pull-out force was shown to be increased by between three and five times compared to smooth surface frames, using a wave amplitude of 0.1 mm and wavelengths varying between 0.25 and 0.50 mm.

Effect of the composition of multicomponent powders on the mechanical and tribotechnical properties of coatings obtained by laser additive technologies

The paper presents the results of metallographic studies and tribotechnical tests of samples of medium-carbon steel 34KhNi3MoA and coatings obtained by laser surfacing of a powder multicomponent charge based on iron and cobalt in a ratio of 3:1 with additives of nano particles of tantalum carbide. The samples were processed with a circular defocused beam and with transverse beam oscillations normal to the scanning speed. Comparative tests for friction and wear were carried out in a pair with a hardened 40Kh steel counterplate. The load and sliding speed during the tests varied discretely. Turbine oil TP 22C was used as a lubricant. It is shown that the introduction of additives of nano-tantalum carbide into the charge reduces friction losses, increases the wear resistance of coatings compared to the charge without carbides and the base material. The wear resistance of coatings with an increase in the amount of the hardening phase increases compared to the original steel. It has been established that the technology of laser surfacing with multicomponent coatings with nano particles of tantalum carbide can be used to restore worn surfaces of shaft necks, turbine blades, thrust discs, shut-off valves and other parts operating at high temperatures and in corrosive environments.

THE INFLUENCE OF PROCESSING IN GRANULAR MEDIUM THE TIMING VALVES OF UMZ-4216 ENGINE TO CHANGE THEIR STRENGTH CHARACTERISTICS

Valves of the valve mechanism of an internal combustion engine are the most critical parts that largely determine the power parameters of the engine and its resource. High demands are placed on both mechanical (strength, hardness, etc.) and service properties (corrosion resistance, heat resistance, etc.) of valves. The article shows the results of hardening critical surfaces of valves in granular medium. The research is aimed at solving the urgent problem of increasing the strength characteristics of the timing valve while reducing the total material costs for its production.

COMPUTATIONAL MODELING OF EROSION WEAR OF THE FISHER V500 CONTROL VALVE OF THE SLURRY SUPPLY LINE OF THE CATALYTIC CRACKING FACILITY OF OIL RESIDUES

Erosion of the internal surfaces of pipelines and shut-off valves used in oil production is a very dangerous phenomenon. It occurs as a result of the impact on the metal of mechanical impurities contained in the working environment. Erosion often occurs together with corrosion. The type of destruction under the influence of mechanical impurities is determined by the fluid flow rate, and the intensity and rate of erosion depends on the concentration and composition of mechanical impurities. Solving the problem of effectively determining the degree of adverse environmental impact depending on various parameters requires the development of new approaches, such as modeling. Modeling of hydrodynamics to determine critical flow rates and calculation of expected zones and erosion rates is due to the importance of solving the problem of anti-erosion protection. In this paper, CFD modeling of hydrodynamics and erosive wear of the control valve of the suspension line of the catalytic cracking unit is performed in the ANSYS Fluent software package. The flow velocities are calculated, and the areas affected by critical velocities at which corrosion erosion occurs are also shown. The effect of density and content of mechanical impurities on the erosion rate is shown.

Abstract 10337: Early Adaptation of the Mitral Valve After St-Elevation Myocardial Infarction

Introduction: Ischemic mitral regurgitation (IMR) is associated with worse outcomes and higher mortality after myocardial infarction (MI). Clinical observations and experimental data have shown that mitral valve leaflets have the potential to enlarge over time to compensate left ventricular remodeling and prevent IMR. Previous animal studies have demonstrated that MI is associated with fibrotic changes in the mitral valve leaflets and prevent this adaptive compensation. However, the timing of mitral valve geometric changes are not well described. While previous data shows an increase in leaflet size at 6 and 12 months after MI, its short-term evolution after an ischemic event is not well documented. Methods: Twenty-two patients with ST-elevation myocardial infarction and initial left ventricular ejection fraction ≤ 45% were enrolled in Quebec Heart and Lung Institute. Participants had 3D transthoracic echocardiography (TTE) at baseline and 3 months, as well as cardiac magnetic resonance (CMR) at 3-month follow-up. Mitral valve leaflet size was measured from the 3D TTE using a custom software (Omni4D). CMR was used to derive left ventricular volumes, function and mitral regurgitant volume. Significant IMR was defined as a mitral regurgitant fraction ≥ 15% derived from the 3-month CMR. Results: Twenty-one of the 22 patients completed the imaging follow-up. Left ventricular ejection fraction at 3 months was 53 ± 10% (range from 37 to 69%). Eight patients (38%) had mild IMR at 3 months. Mitral valve surface area was significantly increased at 3 months compared with baseline for patients without IMR (10.96 ± 1.78 cm 2 vs 9.51 ± 1.62 cm 2 ; p = 0.001). Valve enlargement vs baseline was significantly greater in patients without IMR (+17 ± 13% vs -5 ± 4% for those with IMR at follow-up, p=0.0007). Conclusions: Mitral valvular surface increases within the first few months after MI, but not in all patients. Adequate valve enlargement seems related to the absence of IMR at 3 months.

ODP451 A Case of Papillary Thyroid Cancer Presenting with Marantic Endocarditis and Recurrent Stroke

Abstract Marantic endocarditis or non-bacterial thrombotic endocarditis (NBTE) is characterized by the presence of vegetations on cardiac valves, which consist of fibrin and platelet aggregates and are devoid of inflammation or bacteria. The hypercoagulable state associated with malignancy is well known to be associated with NBTE. Here we report a rare case of Papillary Thyroid Cancer presenting with Marantic Endocarditis and Recurrent Stroke. A 52-year-old lady, with medical background of hypertension, presented to the Emergency Department with history of sudden onset of difficulty in speaking for 3 days. On examination she had slurred speech and tongue deviation to the right side. Neurological examination was otherwise normal. Imaging revealed left frontal, right frontal and left cerebellar infarcts. Transthoracic Echocardiogram showed a large, highly mobile vegetation 18 mm in size, attached to the posterior mitral valve leaflet as well as severe Mitral Regurgitation. She was diagnosed as a case of Cardioembolic ischemic stroke due to endocarditis. She completed a course of empiric antibiotic therapy. However, her blood cultures and fungal culture revealed no growth. After 5 years, she again presented to the hospital with acute stroke. Trans esophageal Echocardiography now revealed multiple filamentous vegetations on the atrial surface of mitral valve, largest measuring 20 mm×4 mm. Her inflammatory markers were negative and 3 sets of blood cultures were again negative. A question was raised, as to whether the filamentous masses represent prolapsing ruptured chordae tendinae rather than vegetations. FDG PET-CT scan was thus performed and revealed: Left thyroid lobe focal uptake seen with an FDG-avid left parajugular lymph node. Ultrasound neck was then performed, which showed bilateral thyroid nodules with high suspicion ultrasound pattern per American Thyroid Association: ill-defined nodule seen in the lower pole measuring 8×8×7 mm with multiple foci of macrocalcification. Thyroid function tests were normal. Ultrasound guided thyroid fine needle aspiration (FNA) biopsy of the left thyroid nodule was performed. The cytology report was consistent with papillary thyroid carcinoma. She is planned for total thyroidectomy, after undergoing mitral valve replacement surgery. This case illustrates one of the paraneoplastic syndromes associated with thyroid cancer. A hypercoagulable state has been observed in several types of thyroid cancer, although the pathogenesis has not been well studied. The etiology of cancer-associated coagulopathy is complex, related to an imbalance in the hemostatic system and abnormal levels of coagulation factors. Further studies on the occurrence of thrombosis in different types of thyroid cancer would help to inform clinical practice in the management of thyroid cancer, including the need for anticoagulation in certain situations. Presentation: No date and time listed