Shear Velocity Research Articles

Computational Fluid Dynamics (CFD) Modeling of Material Transport through Triply Periodic Minimal Surface (TPMS) Scaffolds for Bone Tissue Engineering.

Cell-laden, scaffold-based tissue engineering methods have been successfully utilized for the treatment of bone fractures. In such methods, the rate of scaffold biodegradation, transport of nutrients, and removal of cell metabolic wastes are critical fluid-dynamics factors, affecting tissue regeneration. Therefore, there is a critical need to identify the underlying material transport mechanisms associated with stem cell-driven, scaffold-based bone tissue regeneration. The objective of the work is to establish computational fluid dynamics (CFD) models to identify the consequential mechanisms behind internal and external material transport through/over porous bone scaffolds designed based on the principles of triply periodic minimal surfaces (TPMS). In this study, advanced CFD models were established based on ten TPMS designs for analyzing (i) single-unit internal flow, (ii) single-unit external flow, and (iii) cubic, full-scaffold external flow. The main fluid characteristics influential in bone regeneration, including flow velocity, pressure, and wall shear stress (WSS), were analyzed to assess material transport internally through and externally over the TPMS designs. Schwarz Primitive (P) appeared to have the lowest level of flow pressure and WSS (desirable for development of bone tissues). An analysis of streamline velocity exhibited an increase in velocity togther with a depiction of turbulent motion along the curved surfaces of the TPMS designs. Besides, pressure buildup was observed within the inner channels of almost all the TPMS designs. Overall, the outcomes of this study pave the way for optimal design and fabrication of bone-like tissues with desirable medical properties.

Influence of phase difference and amplitude ratio on Kelvin–Helmholtz instability with dual-mode interface perturbations

A two-component discrete Boltzmann method (DBM) is employed to study the compressible Kelvin–Helmholtz (KH) instability with dual-mode interface perturbations, consisting of a fundamental wave and a second harmonic. The phase difference is analyzed in two distinct ranges, and the amplitude ratio is studied by varying the amplitude of either the first or second harmonic. The global average density gradient and the global mixing degree are analyzed from a hydrodynamic non-equilibrium perspective. The thermodynamic non-equilibrium (TNE) intensity is probed as a thermodynamic non-equilibrium variable. The system is also explored from a geometric perspective, with a focus on the rotation of two vortices, the mixing layer width, and the non-equilibrium area. Physically, under the influence of shear velocity, the fluid interface becomes distorted and progressively elongated, resulting in the formation of two small vortex structures and an enhancement of the physical gradient. The two vortices then begin to interact and merge into a single large vortex with complex fluid structures. Consequently, the physical gradient decreases, and the local TNE intensity weakens. Subsequently, the material interface elongates further, increasing the non-equilibrium region and enhancing the local TNE intensity. Finally, the physical gradient decreases due to dissipation and/or diffusion, weakening the local TNE intensity.

Identifying dehydration-induced shear velocity anomaly in the Earth’s core-mantle boundary

Identifying dehydration-induced shear velocity anomaly in the Earth’s core-mantle boundary

Airflow analysis of pediatric upper airway following maxillary expansion using computational fluid dynamics

Purpose: The objective of this study is to numerically analyze and visualize changes in airflow characteristics due to maxillary expansion in pediatric patients using computational fluid dynamics (CFD).Materials and Methods: CBCT data from pediatric patients with an apnea-hypopnea index of over 1, habitual mouth breathing, and a constricted maxilla were used. For orthodontic treatment, maxillary expansion was conducted, and CBCT scans were taken before and after expansion. 3D models of the nasal airway, created from CBCT data, were converted into smoothed, mesh-divided models. CFD analysis was conducted and various parameters which can be used to evaluate flow obstruction, including pressure, velocity, and wall shear stress, were analyzed.Results: In the patient with rapid expansion, constriction sites with high pressure, velocity, and wall shear stress distribution were identified in the anterior and posterior regions of the nasal cavity, while in the slow expansion patient, these high pressure, velocity, and wall shear stress distributed constriction sites were found in the anterior and mid-inferior regions of the nasal cavity. In both patients, after expansion, the flow-related variables that were highly distributed prior to expansion decreased, and their maximum values were also reduced.Conclusion: CFD analysis enabled the identification of constriction sites within upper airway before undergoing expansion, and improvement in airflow was confirmed after both rapid and slow maxillary expansion in pediatric patients. CFD analysis on patient-specific upper airway models is expected to aid in precisely identifying the problematic areas of respiratory obstruction, thereby assisting in the selection of personalized treatment methods.

Computational Fluid Dynamics (CFD) Analysis of 3D Printer Nozzle Designs

Additive manufacturing, particularly 3D printing, has garnered significant attention recently due to its flexibility, precision, and sustainability. Fused Deposition Modeling (FDM)-based 3D printers are among the most popular in the field due to their low cost, practical usage, and print quality. However, one of the major disadvantages of these 3D printers is low print quality or print resolution. The major factor affecting print quality is the nozzle design, including nozzle geometry. Thus, many works in the literature have focused on enhancing 3D printing quality, especially on the nozzle design, which has a substantial impact on printing performance. In this study, the effects of nozzle geometry in three aspects were investigated with a computational fluid dynamics (CFD) perspective: the die angle, and the outlet’s size and shape. The CFD results show that the die angle primarily affects the shear stresses developed in the nozzle, the outlet’s size predominantly impacts velocity and pressure difference, and the outlet’s shape affects shear stress, velocity, and pressure difference to a lesser extent compared to the die angle and size.

Investigation of the Pulmonary Artery Hypertension Using an Ad Hoc OpenFOAM CFD Solver

Cardiovascular diseases are a group of disorders that affect the heart and blood vessels, representing a leading cause of death worldwide. With the help of computational fluid dynamics, it is possible to study the hemodynamics of the pulmonary arteries in detail and simulate various physiological conditions, thus offering numerous advantages over invasive analyses in the phases of diagnosis and surgical planning. Specifically, the aim of this study is the fluid dynamic analysis of the pulmonary artery, comparing the characteristics of the blood flow in a healthy subject with that of a patient affected by pulmonary arterial hypertension. We performed CFD simulations with the OpenFOAM C++ library using a purposely developed solver that features the Windkessel model as a pressure boundary condition. This methodology, scarcely applied in the past for this problem, allows for a proficient analysis and the detailed quantification of the most important fluid-dynamic parameters (flow velocity, pressure distribution, and wall shear stress (WSS)) with improved accuracy and resolution when compared with classical simulation and diagnostic techniques. We verified the validity of the adopted methodology in reproducing the blood flow by relying on experimental data. A detailed comparative analysis highlights the differences between healthy and pathological cases in hemodynamic terms. The outcomes of this work contribute to enlarging the knowledge of the blood flow characteristics in the human pulmonary artery, revealing substantial differences between the two clinical scenarios investigated and highlighting how arterial hypertension drastically changes the blood flow. The analysis of the data confirmed the importance of CFD as a supportive tool in understanding, diagnosing, and monitoring the pathophysiological mechanisms underlying cardiovascular diseases, proving to be a powerful means for personalizing surgical treatments.

Sound Velocities of the Hydrous Iron‐Rich HH1‐Phase: Implications for Lower Mantle Seismic Heterogeneities

AbstractWe investigated the compressional and shear velocities, VP and VS, of the HH1‐phase by combining the inelastic x‐ray scattering and x‐ray diffraction experiments. In the pressure range of 64.7–79.6 GPa and at room temperature, the VP and VS were measured to be 9.66–11.05 and 4.9–6.4 km·s⁻1, respectively. We employed a simplified model to quantitatively discuss the sound velocity differences between hydrous and anhydrous phase assemblages in the mid‐lower mantle, revealing that the hydrous assemblage exhibits increased VS and a reduced VP/VS ratio compared to its anhydrous counterpart. This suggests formation of seismic scatterers in the mid‐lower mantle exhibiting high VS anomalies may be related to the heterogeneous distribution of water. Moreover, the interpretation of a large VP/VS ratio as indicating the presence of water in the upper mantle and crust may not be applicable for detecting water in the lower mantle.

Differentiated Impacts of Central and Eastern Atlantic Niño on Hurricane Activity in the Tropical North Atlantic

AbstractRecent research highlights the influence of the Atlantic Niño on the likelihood of strong hurricanes forming in the tropical Atlantic. This phenomenon increases the risk of hurricanes impacting the Caribbean islands and the United States. A recent study identifies two distinct types of the Atlantic Niño, with warming concentrated in the central (CA) and eastern (EA) equatorial Atlantic, respectively. By analyzing observational and reanalysis data, we investigated how these two types of the Atlantic Niño affect hurricane activity. The findings reveal that the CA Niño enhances hurricane frequency south of 20°N, while the CA Niña promotes hurricanes north of 20°N. The CA Niño exerts a more significant influence on hurricanes than the EA Niño, primarily by affecting wind shear, relative vorticity, and vertical velocity. In contrast, the EA Niño mainly impacts relative humidity and African Easterly Waves. These insights could improve the accuracy of seasonal hurricane forecasts.

Evaluating of the Relationships between aAverage Particle Size and Microstructure-Mechanical Properties of Materials Produced in Different Compositions using Ultrasonic Method

Pulse-echo ultrasonic test, which is one of the non-destructive testing methods, was used to measure ultrasonic quantities such as longitudinal velocity (VL), shear velocity (VT) and attenuation coefficient (α) in FeCrMn composites. The corresponding elastic constants were determined depending on the longitudinal and transverse velocity. The aim was to reveal the correlation between the microstructural and mechanical properties of FeCrMn composites and ultrasonic quantities. The effect of adding Cr particles on VL and VT velocities is obviously attributed to the change in elastic and shear modulus of FeCrMn composites. It was found that both VL and VT velocities, Young’s modulus (E) and shear modulus (G), as well as hardness values, changed approximately linearly with increasing Cr content. In this study, samples with different volumetric compositions were produced using the powder metallurgy method. It has been revealed that both the applied method and the increase in the amount of Cr have a significant effect on the velocities of VL and VT. The increase in VL and VT is due to the increase of Cr particles, the homogeneous distribution of Cr, the formation of samples especially at a certain temperature, and the decrease of porosity. As a result of these, a decrease in attenuation values was observed depending on the mean grain size. Elastic constants were found to vary in the same way as ultrasonic velocities. By increasing the Cr content both the hardness values and the shear modulus were improved and a good correlation was observed with the grain size.

Flow characteristics in compound channels with skewed and inclined floodplains

ABSTRACT Understanding the flow characteristics of rivers in both their inbank and overbank flow conditions is an important task for engineers. So far, many studies have been carried out in compound channels with prismatic and non-prismatic floodplains. However, we still don’t understand the effect of the floodplain’s side slope on the flow field in compound channels. This paper presents the results of experiments on compound channels with skewed and inclined floodplains (lateral slope of 0.075). Velocity and boundary shear stress were measured at various experimental sections for different relative depths and two skew angles of 3.81º and 11.31º. Using the measured data, the secondary currents pattern, the apparent shear forces at the vertical interface between the main channel and floodplains, and the discharge distribution in the main channel and the floodplains along the flume have been investigated. The results of the experiments were then compared to the experimental data of the skewed compound channel with flat floodplains. The research shows that due to lateral flow and momentum exchange between flume subsections, the flow velocity, bed shear stress, and percentage discharge on the diverging floodplain are greater than those on the converging floodplain with the same cross-sectional geometry.

Hemodynamic Simulation Approach to Understanding Blood Flow Dynamics in Stenotic Arteries

Stenosis, the narrowing of arteries, significantly alters blood flow dynamics and is a major contributor to cardiovascular diseases such as heart attacks and strokes. Understanding the hemodynamic behavior of blood flow through stenotic arteries is crucial for developing effective treatments and interventions. This study presents a hemodynamic simulation approach to explore the effects of varying degrees of stenosis on blood flow characteristics, including velocity distribution, shear stress, and pressure gradient. Simulations were conducted for stenosis degrees ranging from 10% to 80%, with results demonstrating a clear relationship between stenosis severity and changes in blood flow dynamics. As stenosis increased, the velocity of blood flow escalated, reflecting the body's compensatory mechanisms to overcome increased resistance. Shear stress on arterial walls also heightened, particularly at the stenotic entry and exit points, which could contribute to endothelial injury and plaque formation. Additionally, the pressure gradient across the stenotic section increased with the degree of stenosis, indicating a higher energy requirement for blood circulation. These findings provide critical insights into the hemodynamic implications of arterial stenosis and underscore the importance of early detection and intervention in preventing severe cardiovascular events.

Loosely coupled under-resolved LES/RANS simulation augmented by sparse near-wall measurement

We investigate scenarios, where only sparse wall shear stress measurements are available, while accurate wall shear stress and velocity profiles are sought. Applying discrete adjoint-based data assimilation, with only near-wall measurements, accurate wall shear stress profiles are achieved at the expense of unrealistic velocity profiles. We therefore add and employ internal reference data generated by performing a relatively cheap hybrid simulation. We modified the dual-mesh hybrid LES/RANS framework recently proposed by Xiao and Jenny (J Comput Phys 231(4):1848–1865, 2012, https://doi.org/10.1016/j.jcp.2011.11.009) by loosely coupling under-resolved LES in the interior with steady RANS near the walls. The framework was developed in OpenFOAM and tested for flow over periodic hills with Re = 10,595. Results show that the devised framework outperforms conventional dual-mesh hybrid LES/RANS and standalone sparse wall-data assimilated RANS models. Graphical abstract Horizontal mean velocity component U1 (top plot) and wall shear stress (friction coefficient Cf) profiles at the lower wall (bottom plot) obtained with S-RANS and assimilation of sparse wall shear stress dataGraphical abstract

Experimental and Numerical Investigations of the Sediment Abrasion Mechanism at the Leading Edge of an Airfoil

Multiple engineering projects have confirmed that hydraulic machinery operating in sediment-laden rivers undergoes sediment abrasion. Guide vanes are among the most severely worn flow-passing components and have long been a key research focus in hydraulic machinery. In this research, a wear test of the NACA0012 cascade under a 10° incoming flow angle was carried out in the Venturi test system, and the evolution process of the wear was analyzed. The three-dimensional flow channel of the cascade was constructed, and the Finnie wear model was adopted for computational fluid dynamics (CFD) simulations to analyze the wear mechanism at the initial stage. The results indicate that abrasion primarily occurs at the airfoil’s leading edge and progresses through three stages: initiation, development, and stabilization. The calculated results closely matched the latest wear outcomes: In the initial stage, the wear rate density was influenced by the particle impact velocity, angle, volume fraction, and y-direction shear stress. A low-velocity zone near the impact point, combined with rebounding particles causing secondary impacts, increases the particle volume fraction and wear rate density. These secondary impacts are the primary causes of erosion on both the upstream and downstream surfaces. Furthermore, flow separation downstream from the leading edge makes this region highly susceptible to wear. This study provides valuable insights for addressing wear in hydraulic machinery for practical engineering applications.

Numerical study on characteristics of flow accelerated corrosion in a globe valve under different working conditions

Abstract As a part of pipeline systems, globe valves play an important role in cutting off and regulating fluid transmission in fields such as petrochemicals, coal chemicals, and metallurgy. During the transportation of corrosive fluid media, flow accelerated corrosion (FAC) caused by internal flow is the main form of valve failure, which seriously affects the safe and reliable operation of the entire transmission system. In this study, the effects of different valve openings and inlet velocities on characteristics of internal flows and corrosion were investigated by numerical simulations in globe valve. The distributions of velocity, pressure, and wall shear stress were obtained and discussed in detail. The corrosion rate of key components of globe valve was obtained and analyzed to reveal characteristics of FAC. Results show that the FAC is more serious with the increase of inlet velocity while it becomes the more serious at moderate valve opening degree. In addition, wall shear stress was verified to be able to describe FAC in globe valve. The obtained results were quite meaningful for guiding the structural design of globe valves in corrosion suppression, which extends the service life of globe valves and ensures the safety of conveying systems.

Multiscale interstitial fluid computation modeling of cortical bone to characterize the hydromechanical stimulation of lacunar-canalicular network.

Bone tissue is a biological composite material with a complex hierarchical structure that could continuously adjust its internal structure to adapt to the alterations in the external load environment. The fluid flow within bone is the main route of osteocyte metabolism, and the pore pressure as well as the fluid shear stress generated by it are important mechanical stimuli perceived by osteocytes. Owing to the irregular multiscale structure of bone tissue, the fluid stimulation that lacunar-canalicular network (LCN) in different regions of the tissue underwent remained unclear. In this study, we constructed a multiscale conduction model of fluid flow stimulus signals in bone tissue based on the poroelasticity theory. We analyzed the fluid flow behaviors at the macro-scale (whole bone tissue), macro-meso scale (periosteum, interstitial bone, osteon and endosteum), and micro-scale (lacunar-osteocyte-canalicular) levels. We explored how fluid stimulation at the tissue level correlated with that at the cellular level in cortical bone and characterized the distributions of the pore pressure, fluid velocity and fluid shear stress that the osteocytes experienced across the entire tissue structure. The results showed that the initial conditions of intramedullary pressure had a significant impact on the pore pressure of Haversian systems, but had a relatively small influence on the fluid velocity. The osteocyte which were located at different positions in the bone tissue received very distinct fluid stimuli. Osteocytes in the vicinity of the Haversian Canals experienced higher fluid shear stress stimulation. When the permeability of the LCN was within the range from 10-21m2 to 10-18m2, the distribution of pressure, fluid velocity and fluid shear stress within the osteon near the periosteum and endosteum was significantly different from that in other parts of the bone. However, when the permeability was less than 10-22m2, such a difference did not exist. Particularly, the flow velocity at the lacunae was markedly higher than that in the canaliculi. Meanwhile, the pore pressure and fluid shear stress were conspicuously lower than those in the canaliculi. In this study, we considered the interconnections of different biofunctional units at different scales of bone tissue, construct a more complete multiscale model of bone tissue, and propose that osteocytes at different locations receive different fluid stimuli, which provides a reference for a deeper understanding of bone mechanotransduction.

Assessing the effects of model parameter assumptions on surface-wave inversion results

Surface-wave inversion is a powerful tool for revealing the Earth’s internal structure. However, aside from shear-wave velocity (vS), other parameters can influence the inversion outcomes, yet these have not been systematically discussed. This study investigates the influence of various parameter assumptions on the results of surface-wave inversion, including the compressional and shear velocity ratio (vP/vS), shear-wave attenuation (QS), density (ρ), Moho interface, and sedimentary layer. We constructed synthetic models to generate dispersion data and compared the obtained results with different parameter assumptions with those of the true model. The results indicate that the vP/vS ratio, QS, and density (ρ) have minimal effects on absolute velocity values and perturbation patterns in the inversion. Conversely, assumptions about the Moho interface and sedimentary layer significantly influenced absolute velocity values and perturbation patterns. Introducing an erroneous Moho-interface depth in the initial model of the inversion significantly affected the vS model near that depth, while using a smooth initial model results in relatively minor deviations. The assumption on the sedimentary layer not only affects shallow structure results but also impacts the result at greater depths. Non-linear inversion methods outperform linear inversion methods, particularly for the assumptions of the Moho interface and sedimentary layer. Joint inversion with other data types, such as receiver functions or Rayleigh wave ellipticity, and using data from a broader period range or higher-mode surface waves, can mitigate these deviations. Furthermore, incorporating more accurate prior information can improve inversion results.

The Iron Spin Transitions in Hydrous Fe3+‐Bearing Bridgmanite and Its Geophysical Properties in the Lower Mantle

AbstractHydrous Fe3+‐bearing bridgmanite (Bdg) is potentially a critical water host in the lowermost mantle. The spin transition behaviors of such materials are pivotal for understanding geophysical heterogeneity in the deep Earth but are poorly understood. Here, we investigated the spin transition and related geophysical properties of Fe3+ with associated H defects [Fe3+‐H] at high P‐T conditions using first‐principles simulations. Our calculations predict that the presence of hydrogen reduces the onset pressure of the spin transition of Fe3+ in Bdg, leading to higher fractions of low spin Fe3+. Along standard geotherms, spin transition is predicted to remain incomplete even at the core‐mantle boundary (CMB), and lateral temperature variations would significantly affect the proportions of high and low spin Fe and related properties like elasticity. The thermoelastic property of hydrous Fe3+‐bearing bridgmanite exhibit stronger softening anomalies at the lower mantle conditions compared to dry system, which potentially enhancing the seismic detectability of the hydrous Bdg in the deep earth. Density profile of hydrous Fe3+‐bearing bridgmanite indicates that the [Fe3+‐H] defect modestly increases the system's density, but much less than that caused by incorporating an equivalent amount of iron alone. This is crucial for understanding regions like Large Low Shear Velocity Provinces (LLSVPs), which exhibits large velocity drops but only minor density changes. The co‐adsorption of Fe and H allows for the introduction of Fe to induce velocity drops without the concomitant sharp increase in density, as pure iron would, thus enabling Fe‐H enrichment as a potential source of LLSVPs.

The Evolution of Dense ULVZs Originating Outside LLSVPs and Implications for Dynamics at LLSVP Margins

AbstractInteractions between multiple‐scale thermochemical heterogeneities in the lowermost mantle, specifically ultralow velocity zones (ULVZs) and large low shear velocity provinces (LLSVPs), are critical in lower mantle dynamics. However, the evolution of ULVZs formed outside LLSVPs has not been thoroughly explored. Here we perform two‐dimensional numerical experiments to examine the evolution of highly dense ULVZs originating beneath cold downwellings and their interactions with the LLSVP. We find that ULVZs with an intrinsic density anomaly more than 500 kg/m3 compared with the ambient lowermost mantle cannot fully enter the LLSVP and would dwell at LLSVP margins for an indefinitely long time. This suggests that dense ULVZ within LLSVPs might have different sources from those outside LLSVPs. The buoyancy number and compositional viscosity of ULVZs are controlling factors on their dynamics and imprints on the core‐mantle boundary (CMB), such as how much the ULVZ protrudes into the LLSVP and the CMB topography beneath the ULVZ. The excess density of ULVZs dictates their width but not their thickness. The oscillations of ULVZ morphology suggest that various types of plumes occur at the LLSVP margin. The mobility of ULVZ implies that the bottom margin of the LLSVP moves much faster than its center. Hot zones exist within the LLSVP near its margins, which may affect the evolution of ULVZs and subducted material nearby. The CMB topography under dense ULVZs are positive unless the buoyancy number of ULVZs exceeds 6.0. These results have intriguing implications for the distribution of ULVZs as well as thermochemical evolution in the lowermost mantle.

Transthoracic cardiac ultrasonic shear wave elastography for detecting myocardial stiffness in healthy and hypertrophic cardiomyopathy individuals

Objective: To explore the feasibility of transthoracic cardiac shear wave elastography (SWE) for non-invasive quantitative measurement of myocardial stiffness in healthy volunteers (HV) and hypertrophic cardiomyopathy (HCM) patients, and analyze the relationship between myocardial shear wave velocity (SWV) and left ventricular diastolic function. Methods: A total of 16 HV who underwent health check-ups and 5 HCM patients who visited the Cardiology Outpatient Clinic at Fujian Medical University Affiliated Union Hospital from September 2022 to October 2023 were prospectively recruited. The SWE technique was used to measure SWV of the basal segment of the interventricular septum, including left ventricular long-axis myocardial shear wave velocity (LA-SWV) and short-axis myocardial shear wave velocity (SA-SWV). The intraclass correlation coefficient (ICC) was employed to evaluate the intra-observer and inter-observer consistency of SWV measurements. Spearman's correlation analysis was performed to evaluate the correlation between baseline characteristics, echocardiography parameters and SWV. Quantitative data were expressed as median (interquartile range) [M (Q1, Q3)]. Results: The HV group had the age of 34.5 (24.0, 51.0) years, including 8 males (50%); the HCM group had the age of 34.0 (27.0, 46.0) years, including 3 males (60%). The intra-observer and inter-observer ICC (95%CI) for LA-SWV measurements were 0.806 (0.592-0.907) and 0.785 (0.471-0.949), respectively, indicating high consistency; the intra-observer and inter-observer ICC (95%CI) for SA-SWV measurements were 0.746 (0.359-0.862) and 0.602 (0.245-0.834), indicating moderate consistency. LA-SWV [1.74 (1.65, 1.77) vs 1.25 (1.22, 1.33) m/s, P<0.001] and SA-SWV [1.98 (1.96, 2.15) vs 1.52(1.46, 1.55) m/s, P<0.001] were significantly higher in HCM group than those in HV group. There was no significant correlation between SWV and gender, age or body mass index (all P>0.05). In the left ventricular long-axis view, interventricular septal end-diastolic thickness (IVSDT) (r=0.749, P<0.001), early diastolic mitral valve flow velocity/early diastolic mitral annular peak motion velocity (E/e') (r=0.669, P<0.001), and left ventricular mass index (LVMI) (r=0.679, P<0.001) were positively correlated with LA-SWV, while e' (r=-0.545, P<0.001) and late diastolic mitral annular peak motion velocity (r=-0.489, P=0.021) were negatively correlated with LA-SWV. In the left ventricular short-axis view, IVSDT (r=0.784, P<0.001), E/e' (r=0.657, P<0.001), and LVMI (r=0.660, P<0.001) were positively correlated with SA-SWV, while e' was negatively correlated with SA-SWV (r=-0.658, P<0.001). Conclusions: The use of SWE technique to measure myocardial SWV can be applied to assess the stiffness differences between normal myocardium and HCM myocardium. Additionally, SWV is correlated with left ventricular diastolic function indices and can effectively evaluate the diastolic dysfunction of the left ventricle caused by HCM.

Tunable motile sperm separation based on sperm persistence in migrating through shear barriers.

Rheotaxis is one of the major migratory mechanisms used in autonomous swimmers such as sperms and bacteria. Here, we present a microfluidic chip using joint rheotaxis and boundary-following behavior that selects sperms based on the motility and persistence. The proposed device consists of a channel decorated with diamond-shaped pillars that create spots of increased velocity field and shear rate. These spots are supposed as hydrodynamic barriers that impede the passage of less motile sperms through the channels, while highly motile sperms were able to overcome the generated barrier and swim through the structures. The proposed device was able to populate the chamber with sorted sperms that were fully viable and motile. The experimental results validated the separation of highly motile sperms with enhanced motility parameters compared with the initial sample. Our device was able to improve linear straight velocity, curvilinear velocity, and average path velocity of the sorted population surpassing 35%, compared with the raw semen. The processing time was also reduced to 20 min.