Valve Shape Research Articles

Description of Two New Species of Stauroneis Ehrenberg (Naviculales, Bacillariophyceae) from the Russian Far East Using an Integrative Approach.

Stauroneis (Naviculales, Bacillariaceae) are widespread, mostly in fresh-water habitats, and account for 343 species. They are described mainly on the basis of morphology and morphometric traits. These characteristics vary during life cycles and may overlap between species, making their identification difficult. We isolated two strains of naviculoid diatoms and examined them using an integrative approach (phylogenetic, morphological, ultrastructural data, and life cycle). Phylogenetic analyses based on chloroplast rbcL gene data showed affinity of the new strains to the genus Stauroneis. Our algae share morphological features typical of Stauroneis but differ from similar species in minimal valve length measurements, valve apex shape, and minimal number of striae in 10 μm. Two strains are distinct from each other in maximal valve length and width, partially valve shape, the number of areolae in 10 μm, and cingulum structure. It was revealed that the strains reproduce via isogamy. Three species delimitation methods (ASAP, PTP, and GMYC) also confirmed that the two closely related new strains represent distinct species. Based on molecular data and phenotypic traits examined within the framework of an integrative approach, we describe two new isolates as Stauroneis urbani sp. nov. and Stauroneis edaphica sp. nov.

Gomphonemavancampianum sp. nov. (Gomphonemataceae, Bacillariophyceae), a new large Gomphonema species from Europe.

During a French biomonitoring survey of the lakes in the region Rhône-Méditerranée-Corse, a large, unknown Gomphonema taxon was observed in a lake in the vicinity of the City of Lyon (Département du Rhône, France), that could not be identified using the currently available literature. Detailed light and scanning electron microscopy investigations revealed the presence of two types of valves, one bearing a thick marginal crest and valves lacking the crest. Following comparison with similar, mostly tropical Gomphonema species, the unknown taxon is described as new: Gomphonemavancampianum sp. nov. Discriminating features of the new species include the peculiar valve shape resembling a Chinese spoon, the broad upper valve part with acuminate tip, the presence of shallow depressions in the axial area, distinctly punctate striae and the occasional presence of the marginal crest. The new species was observed in several samples collected in an oligo- to mesotrophic, calcium-carbonate rich lake with a high ecological quality.

PLUG KNOT PROCESSING OF GLOBE VALVE

Globe valves are essential components in fluid control systems, widely used in various industries for regulating flow. This paper provides an overview of globe valves, focusing on their design, operation, and applications. The distinctive spherical body shape of globe valves allows for precise control of fluid flow through the system. The paper discusses the internal components of globe valves, including the valve stem, disk, seat, and bonnet, highlighting their roles in the valve's functionality. Furthermore, it examines different types of globe valves, such as straight pattern, angle pattern, and Y-pattern valves, along with their specific applications and advantages. Additionally, the paper addresses common materials used in globe valve construction, emphasizing the importance of selecting materials suitable for the operating conditions and the fluid being controlled. Lastly, maintenance and troubleshooting tips are provided to ensure optimal performance and longevity of globe valves in industrial settings. Emphasis is placed on their operational mechanisms, wherein the movement of the plug, controlled by the stem, modulates flow rates precisely. Overall, this paper serves as a comprehensive guide to understanding globe valves and their significance in fluid control systems Keywords: Globe vаlve (type) , valve body, bonnet, plug , disk ,valve seat, stem.

О МОРФОЛОГИЧЕСКОЙ ИЗМЕНЧИВОСТИ ДИАТОМОВОЙ ВОДОРОСЛИ KARAYEVIA SUCHLANDTII (BACILLARIOPHYTA)

This scanning electron microscopy study investigates morphological features of the frustule of the diatom algae Karayevia suchlandtii. The study is based on material collected from the Svir River tributaries (Lake Ladoga basin): Ivina, Yanega, Uslanka,Vazhinka, Oyat, Pasha. Quantitative (the valve length and width, the number of striae in 10 µm) and qualitative (the valve shape and the shape of axial areas, the stiae arrangement) characteristics are analyzed. In the surveyed populations of K. suchlandtii, the minimum values of the valve size are smaller than those given in the original description and the literary, that makes it possible to extend the diagnosis of the species.

CNN-based fully automatic mitral valve extraction using CT images and existence probability maps

Objective. Accurate extraction of mitral valve shape from clinical tomographic images acquired in patients has proven useful for planning surgical and interventional mitral valve treatments. However, manual extraction of the mitral valve shape is laborious, and the existing automatic extraction methods have not been sufficiently accurate. In this paper, we propose a fully automated method of extracting mitral valve shape from computed tomography (CT) images for the all phases of the cardiac cycle. Approach. This method extracts the mitral valve shape based on DenseNet using both the original CT image and the existence probability maps of the mitral valve area inferred by U-Net as input. A total of 1585 CT images from 204 patients with various cardiac diseases including mitral regurgitation were collected and manually annotated for mitral valve region. The proposed method was trained and evaluated by 10-fold cross validation using the collected data and was compared with the method without the existence probability maps. Main results. The mean error of shape extraction error in the proposed method is 0.88 mm, which is an improvement of 0.32 mm compared with the method without the existence probability maps. Significance. We present a novel fully automatic mitral valve extraction method from input to output for all phases of 4D CT images. We suggest that the accuracy of mitral valve shape extraction is improved by using existence probability maps.

The shape of the mitral annulus: A hypothesis of mechanical morphogenesis

This paper investigates the role of mechanics in the morphogenesis of the annulus of the mitral valve. We represent the annulus in its embryonic stage as an elastic ring and we perform a mechanical simulation of the development process applying a distributed torque on the rod: because of the mechanical action of the other growing cardiac chambers on the atrio-ventricular region, it departs from a planar circular shape. The numerical integration of the mathematical rod model subject to a bending load yields a shape very near to the one reported in the medical literature as anatomical reference for healthy patients. To make the comparison quantitative, we illustrate a numerical approach to match two curves in 3D defining their distance in a proper mathematical way. Such a methodology is first applied to compare the annular shape resulting from the mechanical model with an anatomical reference “master” shape and it is then applied to set to clinical data extracted from MRI for a cohort of healthy patients. The good agreement among anatomical master description, numerical mechanical model, and clinical data supports our speculation about a possible role of mechanics in determining the shape of the mitral valve.

A Comparison of Steam Turbine Control Valve Geometries and Their Dynamic Behavior at Part Load

A growing significance of flexible steam turbine operation challenges the control of turbines, as part load operation using control valves can be accompanied by highly unsteady flow conditions. The increased dynamic load induced by pressure forces can reduce the reliable operating range, weaken the valve, and lead to mechanical failures. The geometry of the valve plays a major role in the reduction of dynamic forces. Using a scaled control valve, experiments were conducted with a focus on the dynamic behavior of the valve head. A spherical valve shape favoring unstable operation was used as a reference case, and the desired instability was proven by measurements. Different modified valve geometries based on literature featuring separation edges were then tested against the spherical shape. Results indicate the improved stability of the modified geometries over the reference geometry. For most of the operating range, vibrations were drastically reduced, and the overall flow stabilized.

An In Silico Model for Predicting the Efficacy of Edge-to-Edge Repair for Mitral Regurgitation.

In recent years, transcatheter edge-to-edge repair (TEER) has been widely adopted as an effective treatment for mitral regurgitation (MR). The aim of this study is to develop a personalized in silico model to predict the effect of edge-to-edge repair in advance to the procedure for each individual patient. For this purpose, we propose a combination of a valve deformation model for computing the mitral valve (MV) orifice area (MVOA) and a lumped parameter model for the hemodynamics, specifically mitral regurgitation volume (RVol). Although we cannot obtain detailed information on the three-dimensional flow field near the mitral valve, we can rapidly simulate the important medical parameters for the clinical decision support. In the present method, we construct the patient-specific pre-operative models by using the parameter optimization and then simulate the postoperative state by applying the additional clipping condition. The computed preclip MVOAs show good agreement with the clinical measurements, and the correlation coefficient takes 0.998. In addition, the MR grade in terms of RVol also has good correlation with the grade by ground truth MVOA. Finally, we try to investigate the applicability for the predicting the postclip state. The simulated valve shapes clearly show the well-known double orifice and the improvement of the MVOA, compared with the preclip state. Similarly, we confirmed the improved reverse flow and MR grade in terms of RVol. A total computational time is approximately 8 h by using general-purpose PC. These results obviously indicate that the present in silico model has good capability for the assessment of edge-to-edge repair.

Distributed parameter identification for the Navier–Stokes equations for obstacle detection

We present a parameter identification problem for a scalar permeability field and the maximum velocity in an inflow, following a reference profile. We utilize a modified version of the Navier–Stokes equations, incorporating a permeability term described by the Brinkman’s Law into the momentum equation. This modification takes into account the presence of obstacles on some parts of the boundary. For the outflow, we implement a directional do-nothing condition as a means of stabilizing the backflow. This work extends our previous research published in (Aguayo et al 2021 Inverse Problems 37 025010), where we considered a similar inverse problem for a linear Oseen model with do-nothing boundary conditions on the outlet and numerical simulations in 2D. Here we consider the more realistic case of Navier–Stokes equations with a backflow correction on the outflow and 3D simulations of the identification of a more realistic tricuspid cardiac valve. From a reference velocity that could have some noise or be obtained in low resolution, we define a suitable quadratic cost functional with some regularization terms. Existence of minimizers and first and second order optimality conditions are derived through the differentiability of the solutions of the Navier–Stokes equations with respect to the permeability and maximum velocity in the inflow. Finally, we present some synthetic numerical test based of recovering a 2D and 3D shape of a cardiac valve from total and local velocity measurements, inspired from 2D and 3D MRI.

Optimization of Vortex Tube Design and Performance for Cooling Milling Process

The manufacturing process is required to improve cleanliness and reduce environmental pollution and the exploration of natural resources is limited. One of the manufacturing processes is machining, especially the milling process. The phenomenon during the milling process friction occurs when the workpiece is cut by the milling tool, the effect friction between tool and workpiece occurs temperature rise. To reduce the temperature rise of the milling tool during the workpiece cutting process, an effective and efficient alternative cooling is needed through the use of vortex tubes. The research method was carried out using the Computational Fluid Dynamic (CFD) approach and experiments with the use of inlet pressure = 1-5 Bar, and the parameters of variations in valve shape, number of nozzles, and pipe lengths. The overall results of the CFD and experiment of parameters in inlet pressure on the number of nozzles, valve shapes, and tube lengths, have an impact on the increasing inlet pressure, the higher the thermodynamic characteristics that occur in the vortex tube, but there is a loss of outlet pressure in each parameter. The geometry of the vortex tube selected is the number of nozzles 6, valve fillet shape, and tube length of 50 mm, vortex tube can be used for cooling the milling tool with the addition of a flexible hose at a distance of 5 cm from the tooltip.

Quantitative Morphometric Analysis of Morphologically Similar Species of Fragilaria (Fragilariaceae, Bacillariophyta) Allows Detection of Non-Indigenous Taxa: A Case Study from Lake Ladoga (North of European Russia)

In Lake Ladoga (northwestern Russia), we found a diatom, putatively Fragilaria sublanceolata-baikali, an endemic species from Lake Baikal (southeastern Siberia, Russia). To determine whether this population matches a previously recognized species from Lake Baikal and assess how it differs from other similar Fragilaria taxa, we studied the valve morphology of three morphologically similar Fragilaria populations (the putative F. sublanceolata-baikali, F. pectinalis and F. perminuta) sampled in Lake Ladoga, along with a population of F. sublanceolata-baikali sampled in Lake Baikal. We used light and scanning electron microscopy with a combination of traditional and geometric morphometric methods. To analyze covariation between the valve shape and size (i.e., allometry), we examined differences in the ontogenetic–allometric trajectories at both the interspecific and intraspecific levels. In addition, the effect of size correction of the valve shape on species differentiation was tested. Traditional morphometrics revealed that F. sublanceolata-baikali is distinguished from F. pectinalis and F. perminuta by valve length, while F. pectinalis and F. perminuta are distinguished by striae density. All three species of Fragilaria showed separate and parallel allometric trajectories. In contrast, the two populations of F. sublanceolata-baikali were on a common allometric trajectory, indicating the conspecificity between these populations. Prior to allometric correction, geometric morphometrics was not able fully discriminate between the three Fragilaria species. After allometric correction, the three Fragilaria species were clearly separated in a size-corrected morphospace, whereas the two populations of F. sublanceolata-baikali formed a tightly overlapping group. Thus, we conclude that geometric morphometrics can reliably distinguish between these morphologically similar species of Fragilaria, but only after accounting for allometric shape variation. Our study confirmed morphological similarity between the two geographically distant populations of F. sublanceolata-baikali, which indicates that this taxon can be considered as invasive in Lake Ladoga.

Molecular Investigation of the Achnanthidium minutissimum Complex (Bacillariophyceae) from the Transbaikal Region with the Description of Three New Species

Representatives of the Achnanthidium minutissimum complex have been studied from the Transbaikal region, Russia. The Transbaikal region is known for its unique algal flora and high levels of endemism. Despite the group of monoraphid diatoms being studied quite extensively in this region in recent years, only four species of Achnanthidium have been reported so far. Three new species are described based on LM and SEM microphotographs and molecular data: Achnanthidium baicalonanum sp. nov., A. obscurum sp. nov. and A. angustum sp. nov. Comparison with similar species is given. The new species differ from other species of the genus by valve shape, striae and areolae structure, shape of external distal raphe ends and central area. According to molecular data, the new species form separate branches within the A. minutissimum complex. Ecological preferences of the new species are examined. All of the new species are only known from the Transbaikal region. This study contributes to the understanding of Achnanthidium taxonomy and biogeography and will be an asset to future biomonitoring studies.

Middle and Upper Ordovician linguliformean and craniiformean brachiopods from the Brabant Massif, Belgium: Infaunal giants, encrusting forms and durophagy

Linguliformean and craniiformean brachiopods from the Middle and Upper Ordovician of the Brabant Massif (Belgium) are described for the first time and their palaeoecological and palaeobiogeographical implications are discussed. The restricted and generally poorly preserved material was collected from the Abbaye de Villers (Dapingian–Darriwilian) Formation and from the Katian Huet and Fauquez formations. The dark graptolitic mudstones of the latter unit yielded the most diverse assemblage including seven pseudolingulid, obolid, discinid, and craniopsid species while the Abbaye de Villers and Huet formations only yielded one species each. Due to the scarcity of internal morphological details available, comparison of the pseudolingulid and obolid specimens under investigation here was undertaken by running a Principal Component Analysis using a Log-Shape Ratio transformation of linear measurements. The study of valve shape changes at various growth stages helped identify these Belgian specimens at the family and generic levels. Finally, two unusually long (up to 20 mm) shell repair scars are documented in Pseudolingula and reflect predatory attacks at the anterior margin during early growth stages.

Study on throttling pressure control flow field for traction speed regulation and braking mechanism of the pipeline intelligent plugging robot

This study analyzes the throttling pressure control flow field, and the influencing factors of its traction speed regulation and braking mechanism are determined. Throttling pressure control flow field characteristics of the traction speed regulation and braking mechanism are analyzed and the principle experiment of the throttling pressure control flow field is also carried out. The results show that the throttling pressure control flow field of the traction speed regulation and braking mechanism of the pipeline intelligent plugging robot is greatly affected by the structure and shape of the speed control valve. When the opening of the speed control valve decreases, the flow rate of the backward jet increases, and the flow rate is faster. This is convenient for scouring the front pipe wall of the device. Conversely, as the opening of the speed control valve increases, the maximum deceleration effect can be achieved by increasing the pressure difference before and after the device. This study provides a theoretical basis for the structure design and selection of the pipeline intelligent plugging robot. Moreover, it is helpful for providing data reference and theoretical guidance for the design of passive fluid-propulsion robots in pipes equipped with bypass rotary valves.

МОРФОЛОГИЯ И ТАКСОНОМИЯ РЕДКОГО ВИДА NUPELA SILVAHERCYNIA (LANGE-BERTALOT) LANGE-BERTALOT (BACILLARIOPHYTA)

This electron microscopy study was undertaken to investigate morphological features of the frustule of the diatom Nupella silvahercynia. Materials from Lake Pizanets (Republic of Karelia) and S.I. Genkal’s iconotheca of scanning electron microscopy images of valves collected from Karelian water bodies and watercourses were used. A comparative analysis of quantitative (valve length and width, number of striae and areolae in 10 µm) and qualitative (shape of valve, central and axial areas, arrangement of raphe and striae) features showed the similarity of this species with N. vitiosa, which made it possible to reduce N. silvahercynia to synonymy of the latter. The new data also allowed us to expand the diagnosis and range of N. vitiosa.

On-demand heart valve manufacturing using focused rotary jet spinning

On-demand heart valve manufacturing using focused rotary jet spinning

Gomphonema rajaguruii sp. nov., a new diatom (Bacillariophyceae) species from the Western Ghats, India

A new freshwater diatom species, Gomphonema rajaguruii sp. nov., is described from a wet wall at Mahabaleshwar, Western Ghats, Maharashtra, India. The new species is described based on light and scanning electron microscopy. Features that distinguish this new species from morphologically-similar species such as G. kallarense and G. lujanense include valve shape, which is broad at the centre and narrower near the poles, a distinctly lateral, undulate raphe system and costa-like striae, which are comprised of two rows of slit-like areolae. Although G. rajaguruii also resembles some taxa from the genus Gomphoneis, such as G. eriense and its close allies, it differs from them by lacking an axial plate. The description of G. rajaguruii sp. nov. increases the knowledge on the diatom diversity in the region.

Effect of the geometrical shapes of the helical-spiral shroud intake valve on swirl generation in cylinder of diesel engine

Improving combustion efficiency for diesel engines is an important requirement to save fuel and lower exhaust gas toxicity. In this study, the effect of the geometric shape of the helical-spiral shroud intake valve (HSSIV) for the swirl generation in a diesel engine cylinder was studied, which has important significance in improving the combustion efficiency in a diesel engine.In this study, helical-spiral shroud (HSS) are classified into convex, flat, and concave types according to the installation angle on the intake valve, and their influence on the swirl generation in the cylinder are comparatively analyzed using the computational fluid dynamics (CFD) method. As a result, it is considered that HSSIV with convex shape generates the best swirl and tumble effect in the engine cylinder. The Model 1 with convex shape has a swirl ratio value of 32.5 which is 3.8 times larger at 80CAD, and the tumble ratio value is 48.2 which is 4.5 times larger at 130CAD, compared to Model 0 with no shroud. The findings and results of this study were applied to the diesel engine, but they can also be applied to gasoline engines, and can also be applied to research subjects that need to generate a swirl in the fluid flow path without additional energy consumption and reduction in the volumetric efficiency of the fluid.

Shear and hydrostatic stress regulate fetal heart valve remodeling through YAP-mediated mechanotransduction.

Clinically serious congenital heart valve defects arise from improper growth and remodeling of endocardial cushions into leaflets. Genetic mutations have been extensively studied but explain less than 20% of cases. Mechanical forces generated by beating hearts drive valve development, but how these forces collectively determine valve growth and remodeling remains incompletely understood. Here, we decouple the influence of those forces on valve size and shape, and study the role of YAP pathway in determining the size and shape. The low oscillatory shear stress promotes YAP nuclear translocation in valvular endothelial cells (VEC), while the high unidirectional shear stress restricts YAP in cytoplasm. The hydrostatic compressive stress activated YAP in valvular interstitial cells (VIC), whereas the tensile stress deactivated YAP. YAP activation by small molecules promoted VIC proliferation and increased valve size. Whereas YAP inhibition enhanced the expression of cell-cell adhesions in VEC and affected valve shape. Finally, left atrial ligation was performed in chick embryonic hearts to manipulate the shear and hydrostatic stress in vivo. The restricted flow in the left ventricle induced a globular and hypoplastic left atrioventricular (AV) valves with an inhibited YAP expression. By contrast, the right AV valves with sustained YAP expression grew and elongated normally. This study establishes a simple yet elegant mechanobiological system by which transduction of local stresses regulates valve growth and remodeling. This system guides leaflets to grow into proper sizes and shapes with the ventricular development, without the need of a genetically prescribed timing mechanism.

Navicula sinicomeniscus sp. nov. (Bacillariophyta; Naviculaceae), a new species from southwestern China

Based on light and scanning electron microscopy observations, Navicula sinicomeniscus sp. nov. is described here as a new species from oligotrophic Lake Fuxian in Yunnan Province, China. Characteristics of this new species used to assign it to the genus Navicula include filiform, almost straight to slightly curved raphe structure, lineolate striae, and a row of visible, horizontal areolae positioned on the valve mantle at the apices. The key diagnostic features between the new species and other similar species include: valve shape and size, stria and areola densities, as well as the straightness or degree of bending of the raphe. Comparison with morphologically similar species is discussed in detail. These results can help us further understand the morphological and ecological information of the genus Navicula in Fuxian Lake.