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AbstractThe application of balloon dilation catheters in the management of intracranial arterial stenosis has been gradually increasing. However, studies on the feasibility and effectiveness of different types of balloons remain relatively scarce. In this study, catheter models of three different materials were designed to simulate balloon crimping,splitting, and dilatation processes. A compliant balloon produces large deformations with poor dilatation and a stress concentration phenomenon. During dilatation, the shear stress generated in the intima and lesion area by the semi-compliant balloon was smaller than that generated by the non-compliant balloon. These results demonstrate the feasibility of using semi-compatible balloons. [ABSTRACT FROM AUTHOR]

Introduction: Elevated luminal homocysteine has been linked with cardiovascular disease; however, whether there is a direct effect of homocysteine on blood vessel endothelium is not clear. In this study, the acute effect of luminal homocysteine on iliac artery endothelial function was assessed in the anaesthetised pig. Methods: Hyperhomocysteinaemic blood was injected into an occluded segment of the iliac in the anaesthetised pig for 20 min, and the effect on atrial diameter during the occlusion and during the reactive hyperaemia assessed. Results: No significant changes in arterial diameter or pressure were observed during the incubation period at homocysteine concentrations of 10, 20, 40 and 100 µM. There was also no difference in the magnitude of the iliac diameter increase in the response to reactive hyperaemia when the incubation period was completed. Conclusion: There is no evidence of endothelial dysfunction in response to an acute 20-min elevation in homocysteine in an intact conduit artery. [ABSTRACT FROM AUTHOR]

This research examined the impact of aerobic exercise intensity and dose on acute post‐exercise cerebral shear stress and blood flow. Fourteen young adults (27 ± 5 years of age, eight females) completed a maximal oxygen uptake (V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$) treadmill test followed by three randomized study visits: treadmill exercise at 30% of V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$ for 30 min, 70% of V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$ for 30 min and 70% of V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$ for a duration that resulted in caloric expenditure equal to that in the 30% V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$ visit (EqEE). A venous blood draw and internal carotid artery (ICA) ultrasound were collected before and immediately following exercise. ICA diameter and blood velocity were determined using automated edge detection software, and blood flow was calculated. Using measures of blood viscosity, shear stress was calculated. Aerobic exercise increased ICA shear stress (time: P = 0.005, condition: P = 0.012) and the increase was greater following exercise at 70% V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$ (∆4.1 ± 3.5 dyn/cm2) compared with 30% V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$ (∆1.1 ± 1.9 dyn/cm2; P = 0.041). ICA blood flow remained elevated following exercise (time: P = 0.002, condition: P = 0.010) with greater increases after 70% V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$ (Δ268 ± 150 mL/min) compared with 30% V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$ (∆125 ± 149 mL/min; P = 0.041) or 70% V̇O2max${{\dot{V}}_{{{{\mathrm{O}}}_2}\max }}$ EqEE (∆127 ± 177 mL/min; P = 0.004). Therefore, aerobic exercise resulted in both intensity‐ and dose‐dependent effects on acute post‐exercise ICA blood flow whereby vigorous intensity exercise provoked a larger increase in ICA blood flow compared to light intensity exercise when performed at a higher dose. What is the central question of this study?What are the independent and combined effects of exercise intensity and dose on post‐exercise internal carotid artery (ICA) haemodynamics?What is the main finding and its importance?The combined effects of exercise intensity and dose evoked the greatest haemodynamic response whereby vigorous intensity exercise for a longer duration resulted in the greatest increase in post‐exercise ICA blood flow. Therefore, exercise intensity and dose are important considerations for utilizing exercise to improve cerebrovascular function. [ABSTRACT FROM AUTHOR]

Background: The ductus arteriosus (DA) is critical in maintaining postnatal circulation in neonates with obstructed systemic circulation (OSC) and pulmonary circulation (OPC). We hypothesized that the size of the DA and aortic isthmus (AoI) undergoes adaptive growth in utero to counteract the hemodynamic challenges in these congenital heart diseases (CHD). Methods: Postnatal echocardiograms of neonates diagnosed prenatally with ductal-dependent CHD who were started on prostaglandins within 24 h of birth were reviewed. We assessed the cross-sectional area of the aortic valve opening, pulmonary valve opening, AoI, and DA by calculating (diameter)2/body surface area. Neonates were classified into OSC or OPC then subgrouped depending upon the patency of semilunar valves: OSC with and without aortic atresia (OSC-AA and OSC-nAA, respectively) and OPC with and without pulmonary atresia (OPC-PA and OPC-nPA, respectively). Results: Ninety-four cases were studied. The DA in OSC was significantly larger than OPC, and the DA in OSC-AA was significantly larger than OSC-nAA. The size of the AoI was significantly larger in OPC than OSC and larger in OSC-AA than OSC-nAA. Within the OSC-nAA group, there was no significant difference in the size of the DA, AoI, or pulmonary valve opening between those with retrograde flow (RF) at the AoI and without (nRF) except the aortic valve opening was significantly larger in nRF. All groups had comparable cross-sectional areas of systemic output. Conclusions: Our findings suggest that DA and AoI show compensatory growth to maintain critical blood flow to vital organs against primary anatomical abnormalities in ductus-dependent CHD. (249 words) [ABSTRACT FROM AUTHOR]

As the innermost monolayer of the vasculature, endothelial cells (ECs) serve as the interface for multiplex signal transduction. Directly exposed to blood-borne factors, both endogenous and exogenous, ECs actively mediate vascular homeostasis and represent a therapeutic target against cardiometabolic diseases. ECs act as the first-line gateway between gut-derived substances and vasculature. Additionally, ECs convert blood flow-exerted hemodynamic forces into downstream biochemical signaling to modulate vascular pathophysiology. Besides, ECs can sense other forms of stimuli, like cell extrusion, thermal stimulation, photostimulation, radiation, magnetic field, noise, and gravity. Future efforts are still needed to deepen our understanding on endothelial biology. [Display omitted] • ECs are interfaces for multiplex signal transduction in the vasculature. • ECs are gatekeepers between gut-derived substances and vasculature. • ECs convert hemodynamic forces to biochemical signals, mediating vasopathology. • ECs are sensitive to various environmental stimuli. [ABSTRACT FROM AUTHOR]

Researchers have hypothesized that high-intensity interval exercise (HIIE) and moderate-intensity continuous exercise (MOD) lead to different patterns of shear stress in the brachial artery. These differing patterns of shear stress are thought to partially explain the differing chronic adaptations to these two types of exercise. No study has directly compared blood flow characteristics during HIIE and MOD. Sixteen healthy males (Age: 23 ± 3 years) completed two randomly assigned exercise visits: HIIE (10 × 1 min intervals at 90–95% of HRmax with 1 min of recovery between) or MOD (30 min at 70% of HRmax) on an electronically braked cycle ergometer. Brachial artery blood flow velocity and diameter were measured for a total of 12 min during each of the exercise sessions. Both anterograde blood flow (MOD: 191.3 ± 80.3 mL/min, HIIE: 153.9 ± 67.5 mL/min, p = 0.03) and shear rate (MOD: 203.5 ± 78.1 s−1, HIIE: 170.8 ± 55.5 s−1, p = 0.04) were higher during MOD compared to HIIE. Both retrograde blood flow (MOD: −48.7 ± 21.3 mL/min, HIIE: −63.9 ± 23.3 cm/s, p < 0.01) and shear rate (MOD: −51.5 ± 19.8 s−1, HIIE: −73.8 ± 28.4 s−1, p < 0.01) were of greater magnitude during HIIE compared to MOD. During exercise, brachial artery diameter (p = 0.34) did not differ between HIIE and MOD. Continuous moderate cycling exercise leads to higher brachial artery anterograde shear rate and blood flow, but lower retrograde shear rate and blood flow when compared to high-intensity interval exercise. These differences during exercise in blood flow characteristics could shed light on the differing chronic adaptations to these two types of exercise. [ABSTRACT FROM AUTHOR]

Background: Consumption coagulopathy and hemorrhagic syndrome are the typical features of Bothrops sp. snake envenoming. In contrast, B. lanceolatus envenoming can induce thrombotic complications. Our aim was to test whether crude B. lanceolatus and B. atrox venoms would display procoagulant activity and induce thrombus formation under flow conditions. Methods and Principal Findings: Fibrin formation in human plasma was observed for B. lanceolatus venom at 250–1000 ng/mL concentrations, which also induced clot formation in purified human fibrinogen, indicating thrombin-like activity. The degradation of fibrinogen confirmed the fibrinogenolytic activity of B. lanceolatus venom. B. lanceolatus venom displayed consistent thrombin-like and kallikrein-like activity increases in plasma conditions. The well-known procoagulant B. atrox venom activated plasmatic coagulation factors in vitro and induced firm thrombus formation under high shear rate conditions. In contrast, B. lanceolatus venom induced the formation of fragile thrombi that could not resist shear stress. Conclusions: Our results suggest that crude B. lanceolatus venom displays amidolytic activity and can activate the coagulation cascade, leading to prothrombin activation. B. lanceolatus venom induces the formation of an unstable thrombus under flow conditions, which can be prevented by the specific monovalent antivenom Bothrofav®. [ABSTRACT FROM AUTHOR]

Fluid shear stress (FSS) from blood flow, sensed by the vascular endothelial cells (ECs) that line all blood vessels, regulates vascular development during embryogenesis, controls adult vascular physiology and determines the location of atherosclerotic plaque formation. Although a number of papers have reported a crucial role for cell-cell adhesions or adhesion receptors in these processes, a recent publication has challenged this paradigm, presenting evidence that ECs can very rapidly align in fluid flow as single cells without cell–cell contacts. To address this controversy, four independent laboratories assessed EC alignment in fluid flow across a range of EC cell types. These studies demonstrate a strict requirement for cell-cell contact in shear stress sensing over timescales consistent with previous literature and inconsistent with the newly published data. [ABSTRACT FROM AUTHOR]

Background: High mechanical shear stress (HMSS) generated by blood pumps during mechanical circulatory support induces blood damage (or function alteration) not only of blood cell components but also of plasma proteins. Methods: In the present study, fresh, healthy human blood was used to prime a blood circuit assisted by a CentriMag centrifugal pump at a flow rate of 4.5 L/min under three pump pressure heads (75, 150, and 350 mm Hg) for 4 h. Blood samples were collected for analyses of plasma‐free hemoglobin (PFH), von Willebrand factor (VWF) degradation and platelet glycoprotein (GP) IIb/IIIa receptor shedding. Results: The extent of all investigated aspects of blood damage increased with increasing cross‐pump pressure and duration. Loss of high‐molecular‐weight multimers (HMWM)‐VWF in Loop 2 and Loop 3 significantly increased after 2 h. PFH, loss of HMWM‐VWF, and platelet GPIIb/IIIa receptor shedding showed a good linear correlation with mean shear stress corresponding to the three pump pressure heads. Conclusions: HMSS could damage red blood cells, cause pathological VWF degradation, and induce platelet activation and platelet receptor shedding. Different blood components can be damaged to different degrees by HMSS; VWF and VWF‐enhanced platelet activation may be more susceptible to HMSS. [ABSTRACT FROM AUTHOR]

This article provides a method by which the scour and self-burial of spherical bodies, short cylinders, and truncated cones that are induced by bichromatic and bidirectional waves could be derived. The empirical scour and self-burial depth formulas for spherical bodies, short cylinders, and truncated cones are used with a bed shear stress model beneath bichromatic and bidirectional waves. Examples of the results are given for unidirectional bichromatic and bidirectional monochromatic waves. The results appear to agree qualitatively with physical expectations. [ABSTRACT FROM AUTHOR]

High-temperature superconducting (HTS) rare-earth Ba2Cu3O7−x (REBCO) coated conductors (CCs) have significant potential in high-current and high-field applications. However, owing to the weak interface strength of the laminated composite REBCO CCs, the damage induced by the thermal mismatch stress under a combination of epoxy impregnation, cooling, and quenching can cause premature degradation of the critical current. In this study, a three-dimensional (3D) electromagnetic-thermal-mechanical model based on the H-formulation and cohesive zone model (CZM) is developed to study the critical current degradation characteristics in an epoxy-impregnated REBCO CC caused by the damage during a quench. The temperature variation, critical current degradation of the REBCO CC, and its degradation onset temperature calculated by the numerical model are in agreement with the experimental data taken from the literature. The delamination of the REBCO CC predicted by the numerical model is consistent with the experimental result. The numerical results also indicate that the shear stress is the main contributor to the damage propagation inside the REBCO CC. The premature degradation of the critical current during a quench is closely related to the interface shear strength inside the REBCO CC. Finally, the effects of the coefficient of thermal expansion (CTE) of the epoxy resin, thickness of the substrate, and substrate material on the critical current degradation characteristics of the epoxy-impregnated REBCO CC during a quench are also discussed. These results help us understand the relationship between the current-carrying degradation and damage in the HTS applications. [ABSTRACT FROM AUTHOR]

Endothelial dysfunction, prevalent in cardiovascular diseases (CVDs) and linked to conditions like diabetes, hypertension, obesity, renal failure, or hypercholesterolemia, is characterized by diminished nitric oxide (NO) bioavailability—a key signaling molecule for vascular homeostasis. Current two‐dimensional (2D) in vitro studies on NO synthesis by endothelial cells (ECs) lack the crucial laminar shear stress, a vital factor in modulating the NO‐generating enzyme, endothelial nitric oxide synthase (eNOS), under physiological conditions. Here we developed a tracer‐based metabolomics approach to measure NO‐specific metabolites with mass spectrometry (MS) and show the impact of fluid flow on metabolic parameters associated with NO synthesis using 2D and 3D platforms. Specifically, we tracked the conversion of stable‐isotope labeled NO substrate L‐Arginine to L‐Citrulline and L‐Ornithine to determine eNOS activity. We demonstrated clear responses in human coronary artery endothelial cells (HCAECs) cultured with 13C6, 15N4‐L‐Arginine, and treated with eNOS stimulator, eNOS inhibitor, and arginase inhibitor. Analysis of downstream metabolites, 13C6, 15N3 L‐Citrulline and 13C5, 15N2 L‐Ornithine, revealed distinct outcomes. Additionally, we evaluated the NO metabolic status in static 2D culture and 3D microvessel models with bidirectional and unidirectional fluid flow. Our 3D model exhibited significant effects, particularly in microvessels exposed to the eNOS stimulator, as indicated by the 13C6, 15N3 L‐Citrulline/13C5, 15N2 L‐Ornithine ratio, compared to the 2D culture. The obtained results indicate that the 2D static culture mimics an endothelial dysfunction status, while the 3D model with a unidirectional fluid flow provides a more representative physiological environment that provides a better model to study endothelial dysfunction. [ABSTRACT FROM AUTHOR]

In this work, a priori analysis of machine learning (ML) strategies is carried out with the goal of data-driven wall modeling for large eddy simulation (LES) of gas turbine film cooling flows. High-fidelity flow datasets are extracted from wall-resolved LES (WRLES) of flow over a flat plate interacting with the coolant flow supplied by a single row of 7-7-7 shaped cooling holes inclined at 30 degrees with the flat plate at different blowing ratios (BR). The WRLES are performed using the high-order Nek5000 spectral element computational fluid dynamics (CFD) solver. Light gradient boosting machine (LightGBM) is employed as the ML algorithm for the data-driven wall model. Parametric tests are conducted to systematically assess the influence of a wide range of input flow features (velocity components, velocity gradients, pressure gradients, and fluid properties) on the accuracy of ML wall model with respect to prediction of wall shear stress. In addition, the use of spatial stencil and time delay is also explored within the ML wall modeling framework. It is shown that features associated with gradients of the streamwise and spanwise velocity components have a major impact on the prediction fidelity of wall model, while the effect of gradients of wall-normal velocity component is found to be negligible. Moreover, adding flow feature information from an x-y-z spatial stencil significantly improves the ML model accuracy and generalizability compared to just using local flow features from the matching location. Overall, highest prediction accuracy is achieved when both spatial stencil and time delay features are incorporated within the data-driven wall modeling paradigm. [ABSTRACT FROM AUTHOR]

Protein denaturation and aggregation resulting from the effects of interfacial stress, often enhanced by flow and shear stress, pose significant challenges in the production of therapeutic proteins and monoclonal antibodies. The influence of flow on protein stability is closely intertwined with interfacial effects. In this study, we have developed a microfluidic device capable of exposing low volume (< 320 µL) protein solutions to highly uniform shear. To disentangle the synergistic impact of flow and interfaces on protein aggregation, we fabricated two devices composed of different materials, namely poly(methyl methacrylate) (PMMA) and stainless steel. Upon application of shear, we observed formation of protein particles in the micron-size range. Notably, The number of particles generated in the steel devices was ∼ 3.5 fold lower than in the PMMA device, hinting at an interface-mediated effect. With increasing the protein concentration from 1 to 50 mg/mL we observed a saturation in the amount of aggregates, further confirming the key role of solid-liquid interfaces in inducing particle formation. Introduction of non-ionic surfactants prevented protein aggregation, even at the highest tested protein concentration and low surfactant concentrations of 0.05 mg/mL. Overall, our findings corroborate the synergistic impact of shear and interface effects on protein aggregation. The device developed in this study offers a small-scale platform for assessing the stability of antibody formulations throughout various stages of the development and manufacturing process. [ABSTRACT FROM AUTHOR]

The endothelial glycocalyx (EG), covering the luminal side of endothelial cells, regulates vascular permeability and senses wall shear stress. In sepsis, EG undergoes degradation leading to increased permeability and edema formation. We hypothesized that restoring EG integrity using liposomal nanocarriers of preassembled glycocalyx (LNPG) will restore normal venular permeability in lipopolysaccharide (LPS)-induced sepsis model of mice. To test this hypothesis, we designed a unique perfusion microchamber in which the permeability of isolated venules could be assessed by measuring the concentration of Evans blue dye (EBD) in microliter samples of extravascular solution (ES). Histamine-induced time- and dose-dependent increases in EBD in the ES could be measured, confirming the sensitivity of the microchamber system. Notably, the histamine-induced increase in permeability was significantly attenuated by histamine receptor (H1) antagonist, triprolidine hydrochloride. Subsequently, mice were treated with LPS or LPS + LNPG. When compared with control mice, venules from LPS-treated mice showed a significant increased permeability, which was significantly reduced by LNPG administration. Moreover, in the presence of wall shear stress, intraluminal administration of LNPG significantly reduced the permeability in isolated venules from LPS-treated mice. We have found no sex differences. In conclusion, our newly developed microchamber system allows us to quantitatively measure the permeability of isolated venules. LPS-induced sepsis increases permeability of mesenteric venules that is attenuated by in vivo LNPG administration, which also reestablished endothelial responses to shear stress. Thus, LNPG presents a promising therapeutic potential for restoring EG function and thereby mitigating vasogenic edema due to increased permeability in sepsis. NEW & NOTEWORTHY: In sepsis, the degradation of the endothelial glycocalyx leads to increased venular permeability. In this study, we developed a potentially new therapeutic approach by in vivo administration of liposomal nanocarriers of preassembled glycocalyx to mice, which restored venular sensitivity to wall shear stress and permeability in lipopolysaccharide-induced sepsis, likely by restoring the integrity of the endothelial glycocalyx. Using a new microchamber system, the permeability of Evans blue dye could be quantitatively determined. [ABSTRACT FROM AUTHOR]

Diabetic kidney disease (DKD) is a microvascular complication of diabetes, and glomerular endothelial cell (GEC) dysfunction is a key driver of DKD pathogenesis. Krüppel-like factor 2 (KLF2), a shear stress-induced transcription factor, is among the highly regulated genes in early DKD. In the kidney, KLF2 expression is mostly restricted to endothelial cells, but its expression is also found in immune cell subsets. KLF2 expression is upregulated in response to increased shear stress by the activation of mechanosensory receptors but suppressed by inflammatory cytokines, both of which characterize the early diabetic kidney milieu. KLF2 expression is reduced in progressive DKD and hypertensive nephropathy in humans and mice, likely due to high glucose and inflammatory cytokines such as TNF-α. However, KLF2 expression is increased in glomerular hyperfiltration-induced shear stress without metabolic dysregulation, such as in settings of unilateral nephrectomy. Lower KLF2 expression is associated with CKD progression in patients with unilateral nephrectomy, consistent with its endoprotective role. KLF2 confers endoprotection by inhibition of inflammation, thrombotic activation, and angiogenesis, and thus KLF2 is considered a protective factor for cardiovascular disease (CVD). Based on similar mechanisms, KLF2 also exhibits renoprotection, and its reduced expression in endothelial cells worsens glomerular injury and albuminuria in settings of diabetes or unilateral nephrectomy. Thus KLF2 confers endoprotective effects in both CVD and DKD, and its activators could potentially be developed as a novel class of drugs for cardiorenal protection in diabetic patients. [ABSTRACT FROM AUTHOR]

To determine the sensitivity of vascular endothelial cells to long durations of low-intensity pulsed ultrasound (LIPUS) compared to normal flow and identify the duration that maximizes expression of two mechanosensitive genes related to healthy endothelial function, endothelial nitric oxide synthase (eNOS) and Krüppel-like factor 2 (KLF2). Custom ultrasound exposure tanks were developed and the acoustic field was characterized. Human umbilical vein endothelial cells were seeded into culture plates and exposed to LIPUS at a frequency of 1 MHz and acoustic pressure of 217 kPa for 20 min, 1 h, 6 h, 9 h, or 24 h. As a comparator, other cells were exposed to normal flow. RT-qPCR was used to assess mRNA expression of eNOS and KLF2. Maximum eNOS and KLF2 expression occurred at 6 h and was localized to the beam path. Both genes exhibited qualitatively similar patterns of expression under LIPUS compared to normal flow. LIPUS induced a more rapid beneficial response compared to normal flow, but flow induced higher expression of both genes. eNOS expression after 6 h of LIPUS was dependent on RNA yield and culture duration prior to experiments. Endothelial cells exposed to longer durations of LIPUS than typically employed exhibited greater expression of beneficial genes. The temporal gene expression patterns resulting from LIPUS and normal flow suggest activation of similar signaling pathways. However, LIPUS also caused increased RNA yield that may be linked to proliferation, which would suggest more of a wound healing than atheroprotective phenotype. [ABSTRACT FROM AUTHOR]

The application of ultrafine bubbles a.k.a. nano-bubbles (NBs) in upgrading the flotation recovery of fine particles has been extensively investigated from various perspectives over the last two decades. However, their rheological aspect has not been studied yet, which is presented for the first time in this paper. To this end, the current study addresses the effect of six crucial variables including solid content (5%, 15%, and 25% (w/w)), presence and absence of NBs, inner diameter of a Venturi tube (1.5 and 2.2 mm), pH of pulp (4.5–11) and frother dosage (3, 13, and 33 mg/L) on the variation of rheological parameters i.e. shear stress, shear tension, and viscosity. Ultrafine bubbles were generated in a conditioning tank through the hydrodynamic cavitation mechanism using a fatty-acid-based frother (Flo-Y-S), while the rheological responses were continuously monitored and measured by a rheometer and parallel plate spindle (for pulp) and a double gap spindle (for NBs). Flotation tests were conducted on a high-grade phosphate ore (d80 = 37 µm) using a mechanically agitated Denver®-type (D12) flotation cell. The experimental results revealed that fluid behavior without NBs using 13 mg/L frother was in the range of shear rates less than 1 s−1 non-Newtonian and close to the shear thinning state, while it became completely Newtonian in the range of 1 to 1500 s−1. However, the presence of NBs at the same frother content changed this tendency to non-Newtonian and Newtonian fluids at shear rates of <30 s−1 and >30 s−1, respectively. It was also found that either in acidic (5.5) or strong alkaline (11) domains, the pulp viscosity trends were almost close to each other and varied from 0.002−10 to 0.002−4 Pa.s, respectively. On the other hand, on the same trend, the amount was lowered to three times in the neutral range (7.5) and weak alkalinities (9). Diminishing the inner diameter of the Venturi tube from 2.2 mm to 1.5 mm led to an increment of shear stress and viscosity about twice at the shear rates <100 s−1. The results of evaluating frother dosage showed that an increase in the amount of frother dosage, which reduced bubble dimensions, exceeded the viscosity and the amount of shear stress. Finally, we concluded that the rheological properties significantly impacted the selective separation of NB-assisted flotation processes and need further investigations in the future. [ABSTRACT FROM AUTHOR]

The sudden exposure of venous endothelial cells (vECs) to arterial fluid shear stress (FSS) is thought to be a major contributor to coronary artery bypass vein graft failure (VGF). However, the effects of arterial FSS on the vEC secretome are poorly characterised. We propose that analysis of the vEC secretome may reveal potential therapeutic approaches to suppress VGF. Human umbilical vein endothelial cells (HUVECs) pre-conditioned to venous FSS (18 h; 1.5 dynes/cm2) were exposed to venous or arterial FSS (15 dynes/cm2) for 24 h. Tandem Mass Tagging proteomic analysis of the vEC secretome identified significantly increased fibroleukin (FGL2) in conditioned media from HUVECs exposed to arterial FSS. This increase was validated by Western blotting. Application of the NFκB inhibitor BAY 11-7085 (1 µM) following pre-conditioning reduced FGL2 release from vECs exposed to arterial FSS. Exposure of vECs to arterial FSS increased apoptosis, measured by active cleaved caspase-3 (CC3) immunocytochemistry, which was likewise elevated in HUVECs treated with recombinant FGL2 (20 ng/mL) for 24 h under static conditions. To determine the mechanism of FGL2-induced apoptosis, HUVECs were pre-treated with a blocking antibody to FcγRIIB, a receptor FGL2 is proposed to interact with, which reduced CC3 levels. In conclusion, our findings indicate that the exposure of vECs to arterial FSS results in increased release of FGL2 via NFκB signalling, which promotes endothelial apoptosis via FcγRIIB signalling. Therefore, the inhibition of FGL2/FcγRIIB signalling may provide a novel approach to reduce arterial FSS-induced vEC apoptosis in vein grafts and suppress VGF. [ABSTRACT FROM AUTHOR]

The velocity of an unsteady flow of a viscous fluid of the second-grade MHD-type enclosed between two parallel side walls perpendicular to a plate was obtained by applying the integral transformation. The fluid is required to move by the plate, which over time t = 0 + subjected the fluid to shear stress. The solutions satisfy the given equation as well as the boundary and initial conditions, and they were separated into two types: steady state and transient state. Furthermore, through h → ∞ , we are able to recover the results found in the literature for motion across an infinite plate. Graphs depict the effect of the side walls and the time it takes to reach the steady state. The solutions are shown in graphs and discussed physically to examine the impact of different flow parameters. It is found that the fluid velocity decreases with an increasing fractional parameter β and second-grade parameter α. Also, it is noticed that the fluid velocity decreases with increasing values of Reynolds number and effective permeability. Numerous industrial products, including honey, paints, varnishes, coffee, chocolate and jelly, use this type of fluid flow concept. [ABSTRACT FROM AUTHOR]

Shear stress during bioreactor cultivation has significant impact on cell health, growth, and fate. Mammalian cells, such as T cells and stem cells, in next-generation cell therapies are especially more sensitive to shear stress present in their culture environment than bacteria. Therefore, a base knowledge about the shear stress imposed by the bioprocesses is needed to optimize the process parameters and enhance cell growth and yield. However, typical computational flow dynamics modeling or PCR-based assays have several limitations. Implementing and interpreting computational modeling often requires technical specialties and also relies on many simplifications in modeling. PCR-based assays evaluating changes in gene expression involve cumbersome sample preparation with the use of advanced lab equipment and technicians, hampering rapid and straightforward assessment of shear stress. Here, we developed a simple, cell-based shear stress sensor for measuring shear stress levels in different bioreactor types and operating conditions. We engineered a CHO-DG44 cell line to make its stress sensitive promoter EGR-1 control GFP expression. Subsequently, the stressed CHO cells were transferred into a 96 well plate, and their GFP levels (population mean fluorescence) were monitored using a cell analysis instrument (Incucyte®, Sartorius Stedim Biotech) over 24 hours. After conducting sensor characterization, which included chemical induced stress and fluid shear stress, and stability investigation, we tested the shear stress sensor in the Ambr® 250 bioreactor vessels (Sartorius Stedim Biotech) with different impeller and vessel designs. The results showed that the CHO cell-based shear stress sensors expressed higher GFP levels in response to higher shear stress magnitude or exposure time. These sensors are useful tools to assess shear stress imposed by bioreactor conditions and can facilitate the design of various bioreactor vessels with a low shear stress profile. [Display omitted] • First report on CHO cell-based fluid shear stress sensor in bioprocessing. • Sensor measures overall shear stress using conventional fluorescence microscopy. • Evaluated shear stress levels in commercial bioreactors. • Useful for designing vessels and impellers with low shear profile. [ABSTRACT FROM AUTHOR]

Iatrogenic aortic dissection is a rare but life-threatening complication of coronary artery bypass surgery. We report a case with incidentally detected iatrogenic aortic dissection related to aorta cross-clamping that was successfully managed with watchful follow-up. The decision making was based on 3-dimensional holographic and fluid dynamic analysis guidance. [ABSTRACT FROM AUTHOR]

The global population growth and increasing energy demand pose challenges to the Oil and Gas industry, leading to increased exploration and production in offshore and deep-sea areas. Offshore oilfields in colder regions produce crude oils with higher wax content, causing wax deposition and flow assurance issues in pipelines. Nanoparticle inhibitors can mitigate wax deposition in pipelines. In this study, the performance of zinc oxide nanoparticle is evaluated by measurement of degree of viscosity reduction and wax deposition of a Niger Delta crude oil sample. Wax deposition is determined by cold finger technique. 10g of zinc oxide (ZnO) nanoparticle is mixed in 500mL of crude oil sample. From this experiment, it was observed that at 2rpm (revolutions per minute), the degree of viscosity reduction (DVR) was 31% at 10°C and 3% at 15%. Increase in crude oil temperature enhanced the viscosity of the blank sample and the sample blended with ZnO nanoparticle. However, at lower temperatures of 10 and 15C, the viscosity of the blank crude increased. higher, indicating a poor performance of ZnO on the viscosity of the crude oil sample. The addition of 10g of ZnO nanoparticle had more cumulative wax deposit of 16.76g than the blank crude having a cumulative wax deposit in the cold finger as 14.32g. This implies that 10g nano ZnO did not prevent or reduce the wax deposition in the cold finger, but it was efficient at improving the viscosity and flowability of the Niger Delta crude sample. [ABSTRACT FROM AUTHOR]

This paper presents a static analysis to establish a mathematical model using high-order bending theories to predict the shear strain in the displacement fields for functionally graded beams under bending. The new polynomial shear function developed, which represents the originality of this research work, satisfies the boundary conditions and stress nullities on the lower and upper faces of the section through the thickness. This new model, considering a hyperbolic shape function, does not need a shear correction factor. The material properties are assumed to vary continuously in the thickness direction, based on a simple power-law distribution, in terms of constituent volume fractions. The analytical model is developed by differential equations obtained from the virtual work principle as well as equilibrium equations and boundary conditions considered. The solution model is based on an integral approach to evaluate the displacement field component and the basic constitutive laws. The analytical model is explored using the illustrative case. The results obtained in terms of displacement field including shear strains and shear stresses predicted from the proposed model are compared to those obtained from the literature. [ABSTRACT FROM AUTHOR]

Pulmonary hypertension (PH) is a refractory disease characterized by elevated pulmonary artery pressure and resistance. Drag-reducing polymers (DRPs) are blood-soluble macromolecules that reduce vascular resistance by altering the blood dynamics and rheology. Our previous work indicated that polyethylene oxide (PEO) can significantly reduce the medial wall thickness and vascular resistance of the pulmonary arteries, but the specific mechanism is still unclear.This study was designed to investigate the role and mechanism of PEO on intracellular calcium [Ca2 +] i and cytoskeletal proteins of endothelial cells (ECs) induced by low shear stress (LSS) in PH. Primary Pulmonary Artery Endothelial Cells (PAECs) were subjected to steady LSS (1 dyn/cm2) or physiological shear stress (SS) (10 dyn/cm2) for 20 h in a BioFlux 200 flow system. Calcium influx assays were conducted to evaluate the mechanisms of PEO on [Ca2 +] i. Subsequently, taking the key protein that induces cytoskeletal remodeling, the regulatory light chain (RLC) phosphorylation, as the breakthrough point, this study focused on the two key pathways of PEO that regulate phosphorylation of RLC: Myosin light chain kinase (MLCK) and Rho-associated kinase (ROCK) pathways.Our current research revealed that PEO at LSS (1 dyn/cm2) significantly suppressed LSS-induced [Ca2 +] i and the expression level of transient receptor potential channel 1(TRPC1). In addition, ECs convert LSS stimuli into the upregulation of cytoskeletal proteins, including filamentous actin (F-actin), MLCK, ROCK, p-RLC, and pp-RLC. Further experiments using pharmacological inhibitors demonstrated that PEO at the LSS downregulated cytoskeleton-related proteins mainly through the ROCK and MLCK pathways.This study considered intracellular calcium and cytoskeleton rearrangement as entry points to study the application of PEO in the biomedical field, which has important theoretical significance and practical application value for the treatment of PH. [ABSTRACT FROM AUTHOR]

In this study, one-piece glass cenospheres/aluminum core sandwich is prepared using a pressure infiltration method. In comparison to adhesive bonding, the layers combined by metallurgical bonding are straight and smooth, and the sandwich shows high shear stress of 80.4 MPa. The failure mode is analyzed through a combination of mises stress distribution simulated using the finite element analysis and in-situ strain distribution obtained from a digital image correlation system. After cracks initiated at interfaces, they propagate to nearby layers in the sandwich structure, which can delay the shear failure by avoiding significant damage of core layer. [ABSTRACT FROM AUTHOR]

A cell's mechanical environment regulates biological activities. Several studies have investigated the response of healthy epithelial mammary (MCF10A) and breast cancer (MCF7) cells to vascular and interstitial fluid motion-induced hydrodynamic forces. The mechanical stiffness of healthy and breast cancer cells differ significantly, which can influence the transduction of forces regulating the cell's invasive behaviour. This aspect has not been well explored in the literature. The present work investigates the mechanical response of MCF10A and MCF7 cells to tissue-level interstitial fluid flow. A two-dimensional fluid flow–cell interaction model is developed based on the actual shapes of the cells, acquired from experimental fluorescent images. The material properties of the cell compartments (cytoplasm and nucleus) were assigned in the model based on the literature. The outcomes indicate that healthy MCF10A cells experience higher von Mises and shear stresses than the MCF7 cells. In addition, the MCF7 cell experiences higher strain and displacements than its healthy counterpart. Thus, the different mechano-responsiveness of MCF10A and MCF7 cells could be responsible for regulating the invasive potential of the cells. This work enhances our understanding of mechanotransduction activities involved in cancer malignancy which can further help in cancer diagnosis based on cell mechanotype. [ABSTRACT FROM AUTHOR]

AbstractBottom protection (BP) is a commonly used engineering measure in river training. A 3D hydrodynamic numerical model is established to study the influence of the overall arrangements of BP structures on the hydraulic characteristics of the sharp bends. Under the action of the BP structures group, the maximum longitudinal flow velocity is closer to the water surface vertically and closer to the concave bank laterally compared with no BP. The high shear stress zones on the riverbed at the exit straight section of the bend do not occur. The so-called primary circulation after the apex of the bend gradually weakens and disappears. If the coverage rate of BP is increased to 1.5 times that of the sequential BP, the average longitudinal flow velocity near the bottom of BP decreases by 10% and the average bed shear stress at the outlet section of the bend decreases by 35%. In the staggered BP condition, the average bed shear stress at the outlet section of the bend is reduced by 23% compared with the sequential BP. Moreover, the results show that the protection effects of the dense BP and the staggered BP are better than that of sequential BP. [ABSTRACT FROM AUTHOR]

Organ-on-a-chip technologies show exponential growth driven by the need to reduce the number of experimental animals and develop physiologically relevant human models for testing drugs. In vitro, microfluidic devices should be carefully designed and fabricated to provide reliable tools for modeling physiological or pathological conditions and assessing, for example, drug delivery through biological barriers. The aim of the current study was to optimize the utilization of three existing skin-on-a-chip microfluidic diffusion chambers with various designs. For this, different perfusion flow rates were compared using cellulose acetate membrane, polyester membrane, excised rat skin, and acellular alginate scaffold in the chips. These diffusion platforms were integrated into a single-channel microfluidic diffusion chamber, a multi-channel chamber, and the LiveBox2 system. The experimental results revealed that the 40 µL/min flow rate resulted in the highest diffusion of the hydrophilic model formulation (2% caffeine cream) in each system. The single-channel setup was used for further analysis by computational fluid dynamics simulation. The visualization of shear stress and fluid velocity within the microchannel and the presentation of caffeine progression with the perfusion fluid were consistent with the measured data. These findings contribute to the development and effective application of microfluidic systems for penetration testing. [ABSTRACT FROM AUTHOR]

The Lower Indus River (LIR) in the Southern Sindh has experienced by multiple measurable changes in its planform and longitudinal profiles over the last 100 years. This research deals with a hydrodynamic model coupled with rough set theory (RST) model findings that accounts for the prediction of lateral and vertical morphodynamic evolution observed over the 32 km reach during the flood episode of 2020. Human interferences and hydrodynamic aspects during high flood periods were assessed in the context of channel morphology. Surveyed cross-sections were used to construct the geometry using two-dimensional (2D) Hydrologic Engineering Center's River Analysis System (HEC-RAS) model, and simulation was completed under the unsteady flow values among the highest runoff and bankfull values. The island and natural bend of the river have higher values of velocities and shear stresses, and consequently higher erosion and incision rate was observed. The bank erosion was computed with high precision (R2 = 0.83) based on improved connection of erodibility coefficient and excess shear stress technique. The present study findings will be helpful to assist in the implementation of river protection works at the given locations of Indus River and will serve as a framework for similar river reaches. [ABSTRACT FROM AUTHOR]

AbstractIn the present research work, a comprehensive study on the stress analysis in the two composite pipes bonded by a layer of DP 410 adhesive and a socket buried in the soil has been performed. The pipe material was considered as a four layers of epoxy-fiber glass with different fiber orientations (cross-ply, angle-ply and quasi-isotropic). The soil dimensions and properties as well as the traffic load (H-20) were based on AASHTO. The simulation of the stress analysis was performed using ANSYS software. In the present study, the influences of bed distance, temperature change, internal pressure, traffic load, fiber orientation angle and layups, and gap distance on stress distribution in the buried composite pipe have been investigated. The findings revealed that the annual temperature change in the soil and the pipe enhances the stresses in the joint components to a maximum value of 5.5 MPa at a pipe temperature of −22 °C. Moreover, the outcomes indicated that the adhesive layer is the most sensitive component to any rise in the load prism, as well as other loads, for a buried pipe at a depth of 120 cm. The maximum and minimum state for von Mises stress component were related to, in turn, quasi-isotropic and angle-ply laminations. [ABSTRACT FROM AUTHOR]

Vascular remodeling is a physiological and pathological process in which abnormal changes in vascular cells and non-cellular components lead to the remodeling of inward and outward blood vessel wall or changes in lumen diameter. As the channels for blood flow, blood vessels are continuously affected by hemodynamic forces. When sensing the abnormal blood flow forces, the mechanically sensitive cell membrane structures such as G protein-coupled receptors, ion channels, cell surface glycocalyx, and integrins, as well as the extracellular matrix will induce the process of vascular endothelial dysfunction, endothelial-mesenchymal transition, smooth muscle cell phenotypic switching, pericyte morphological changes and extracellular matrix remodeling to participate in vascular remodeling. As shown by research, abnormal hemodynamics caused abnormal changes in vascular structure and function, which was the basic process for the occurrence and development of pan-vascular diseases such as atherosclerosis, hypertension, diabetes, non-alcoholic fatty liver disease, pulmonary hypertension and COVID-19. This paper reviewed the interaction and molecular mechanism between abnormal hemodynamics and vascular remodeling, and analyzed its influence on the pathogenesis of pan-vascular diseases, which could provide reference for formulating prevention and treatment strategies for pan-vascular diseases. [ABSTRACT FROM AUTHOR]

Background: The study of blood trauma, such as hemolysis in blood‐carrying devices, is crucial due to the high incidence of adverse events like alteration of blood function, bleeding, and multi‐organ failure. The extent of flow‐induced hemolysis, predominantly influenced by stress duration and intensity, is described by established model parameters based on the power law approach. In recent years, various parameters were determined using different Couette shearing devices and donor species. However, they have not been validated due to limited experimental data. Methods: This study provides hemolysis measurements in a Couette shearing device and evaluates the suitability of different power law parameters. The revised Couette shearing device generates well‐defined dynamic stress loads that are repeatedly applied to blood samples at a defined temperature. Human blood samples with an adjusted hematocrit of 30%, were tested with varying repetitions (20 to 80 times). The half‐sinusoidal stress loads had amplitudes of 73 to 140 Pa and exposure times of 24 msec per repetition. The parameters of five common power law hemolysis approaches were then compared with the experimental data. Results: The prediction with the power law model parameters C = 3.458 × 10−6, α = 0.2777 and β = 2.0639 showed a good agreement with the experimental results. Conclusion: The effect of multiple short‐time stresses on hemolysis was investigated to validate the power law hemolysis model with the Couette shearing device of this study. [ABSTRACT FROM AUTHOR]

Epigenetic changes, particularly histone compaction modifications, have emerged as critical regulators in the epigenetic pathway driving endothelial cell phenotype under constant exposure to laminar forces induced by blood flow. However, the underlying epigenetic mechanisms governing endothelial cell behavior in this context remain poorly understood. To address this knowledge gap, we conducted in vitro experiments using human umbilical vein endothelial cells subjected to various tensional forces simulating pathophysiological blood flow shear stress conditions, ranging from normotensive to hypertensive forces. Our study uncovers a noteworthy observation wherein endothelial cells exposed to high shear stress demonstrate a decrease in the epigenetic marks H3K4ac and H3K27ac, accompanied by significant alterations in the levels of HDAC (histone deacetylase) proteins. Moreover, we demonstrate a negative regulatory effect of increased shear stress on HOXA13 gene expression and a concomitant increase in the expression of the long noncoding RNA, HOTTIP, suggesting a direct association with the suppression of HOXA13. Collectively, these findings represent the first evidence of the role of histone‐related epigenetic modifications in modulating chromatin compaction during mechanosignaling of endothelial cells in response to elevated shear stress forces. Additionally, our results highlight the importance of understanding the physiological role of HOXA13 in vascular biology and hypertensive patients, emphasizing the potential for developing small molecules to modulate its activity. These findings warrant further preclinical investigations and open new avenues for therapeutic interventions targeting epigenetic mechanisms in hypertensive conditions. HIGHLIGHTS: In vitro methodologies are employed as an initial approach to identify biomarkers associated with elevated shear stress in hypertensionMechanosignaling mediated by oscillatory shear stress necessitates the involvement of epigenetic modifications, particularly histone‐mediated chromatin compressionEnhanced shear stress levels lead to a reduction in the overall abundance of acetylation marks, specifically H3K4 and H3K27, in endothelial cellsHOXA13 does not play a crucial role in the development of mechanosignaling induced by high shear stressThe data demonstrates a positive Pearson correlation between the long noncoding RNA HOTTIP and HOXA13 [ABSTRACT FROM AUTHOR]

Reducing high mechanical stress is imperative to heal diabetes-related foot ulcers. We explored the association of cumulative plantar tissue stress (CPTS) and plantar foot ulcer healing, and the feasibility of measuring CPTS, in two prospective cohort studies (Australia (AU) and The Netherlands (NL)). Both studies used multiple sensors to measure factors to determine CPTS: plantar pressures, weight-bearing activities, and adherence to offloading treatments, with thermal stress response also measured to estimate shear stress in the AU-study. The primary outcome was ulcer healing at 12 weeks. Twenty-five participants were recruited: 13 in the AU-study and 12 in the NL-study. CPTS data were complete for five participants (38%) at baseline and one (8%) during follow-up in the AU-study, and one (8%) at baseline and zero (0%) during follow-up in the NL-study. Reasons for low completion at baseline were technical issues (AU-study: 31%, NL-study: 50%), non-adherent participants (15% and 8%) or combinations (15% and 33%); and at follow-up refusal of participants (62% and 25%). These underpowered findings showed that CPTS was non-significantly lower in people who healed compared with non-healed people (457 [117; 727], 679 [312; 1327] MPa·s/day). Current feasibility of CPTS seems low, given technical challenges and non-adherence, which may reflect the burden of treating diabetes-related foot ulcers. [ABSTRACT FROM AUTHOR]

The introduction of additives of plant or animal origin into meat products is currently a steady trend in food technologies due to the possibility of obtaining unique properties of products and reducing their cost, which justifies the relevance of the conducted research. The purpose of the study was to build a mathematical algorithm that can determine the regularities of changes in the main parameters of the process of preparing minced meat semi-finished products with vegetable additives, which would help to establish the trends in the development of technical and technological efficiency of mechanisation of the system of fine grinding of raw materials for the production of sausage products. The addition of spelt flour and mushrooms as ingredients to the minced meat mass was investigated, which allows, together with reducing the cost of production of cooked sausage products, significantly improving the organoleptic quality indicators of products, reducing their caloric content and extending the shelf life for consumption. The wild variety of spelt used in this scientific work as an alternative to its cultivated varieties has significantly less allergic activity and, accordingly, a lower proportion of gliadins, which form the basis of wheat gluten; which justifies the practical significance of the study. A microstructural analysis of minced meat of control and experimental samples of boiled sausages was performed, which revealed that the latter category of meat product is characterised by increased density and elasticity due to the inclusion of spelt microparticles in the vacuole of the meat fraction. According to the results of experimental studies, using the "dimension analysis" method and the Federman-Buckingham theorem, it was possible to obtain a criterion equation for the process of heat and mass transfer under conditions of intensive mechanical mixing. These process characteristics were described using the Euler, Fourier, and Sherwood criteria. The compiled function contains the main factors of external influence on raw materials and their physical and mechanical characteristics, which allows adequately assessing the diffusion processes in the technological environment and creating the recommended range when designing technical and technological support for obtaining high-quality food products. [ABSTRACT FROM AUTHOR]

Endothelialized in vitro models for cardiovascular disease have contributed greatly to our current understanding of the complex molecular mechanisms underlying thrombosis. To further elucidate these mechanisms, it is important to consider which fundamental aspects to incorporate into an in vitro model. In this review, we will focus on the design of in vitro endothelialized models of thrombosis. Expanding our understanding of the relation and interplay between the different pathways involved will rely in part on complex models that incorporate endothelial cells, blood, the extracellular matrix, and flow. Importantly, the use of tissue-specific endothelial cells will help in understanding the heterogeneity in thrombotic responses between different vascular beds. The dynamic and complex responses of endothelial cells to different shear rates underlines the importance of incorporating appropriate shear in in vitro models. Alterations in vascular extracellular matrix composition, availability of bioactive molecules, and gradients in concentration and composition of these molecules can all regulate the function of both endothelial cells and perivascular cells. Factors modulating these elements in in vitro models should therefore be considered carefully depending on the research question at hand. As the complexity of in vitro models increases, so can the variability. A bottom-up approach to designing such models will remain an important tool for researchers studying thrombosis. As new techniques are continuously being developed and new pathways are brought to light, research question-dependent considerations will have to be made regarding what aspects of thrombosis to include in in vitro models. • The interplay of endothelial cells, blood, extracellular matrix, and flow is crucial for understanding thrombosis pathways. • Incorporating fundamental aspects of thrombosis into in vitro endothelial models are vital in increasing translatability. • Designing endothelialized models for thrombosis requires a balance between reproducibility, accessibility, and complexity. [ABSTRACT FROM AUTHOR]

It is well‐recognized that blood flow at branches and bends of arteries generates disturbed shear stress, which plays a crucial in driving atherosclerosis. Flow‐generated fluid shear stress (FSS), as one of the key hemodynamic factors, is appreciated for its critical involvement in regulating angiogenesis to facilitate wound healing and tissue repair. Endothelial cells can directly sense FSS but the mechanobiological mechanism by which they decode different patterns of FSS to trigger angiogenesis remains unclear. In the current study, laminar shear stress (LSS, 15 dyn/cm2) was employed to mimic physiological blood flow, while disturbed shear stress (DSS, ranging from 0.5 ± 4 dyn/cm2) was applied to simulate pathological conditions. The aim was to investigate how these distinct types of blood flow regulated endothelial angiogenesis. Initially, we observed that DSS impaired angiogenesis and downregulated endogenous vascular endothelial growth factor B (VEGFB) expression compared to LSS. We further found that the changes in membrane protein, migration and invasion enhancer 1 (MIEN1) play a role in regulating ERK/MAPK signaling, thereby contributing to endothelial angiogenesis in response to FSS. We also showed the involvement of MIEN1‐directed cytoskeleton organization. These findings suggest the significance of shear stress in endothelial angiogenesis, thereby enhancing our understanding of the alterations in angiogenesis that occur during the transition from physiological to pathological blood flow. [ABSTRACT FROM AUTHOR]

The application of low-density polyethylene (LDPE) has been confined to packaging applications due to its inadequate mechanical and tribological characteristics. We propose enhancing LDPE by integrating hard carbon spheres (CSs) to improve its strength, frictional characteristics, and wear resistance. LDPE/CS composites were created by blending LDPE with varying CS amounts (0.5–8 wt.%). Analysis using scanning electron microscopy and Raman spectroscopy confirmed CS presence in the LDPE matrix, with X-ray diffraction showing no microstructural changes post-blending. Thermal characterization exhibited notable improvements in thermal stability (~4%) and crystallinity (~7%). Mechanical properties such as hardness and Young's modulus were improved by up to 4% and 24%, respectively. Tribological studies on different composite samples with varying surface roughness under various load and speed conditions revealed the critical role of surface roughness in reducing friction by decreasing real contact area and adhesive interactions between asperities. Increased load and speed amplified shear stress on asperities, possibly leading to deformation and failure. Notably, integrating CSs into LDPE, starting at 1 wt.%, effectively reduced friction and wear. The composite with the highest loading (8 wt.%) displayed the most significant tribological enhancement, achieving a remarkable 75% friction reduction and a substantial 78% wear reduction. [ABSTRACT FROM AUTHOR]

In this article, a mathematical model is developed to study the effect of Non-Newtonian behavior of blood through stenosed artery considering Herschel-Bulkely fluid model. The constitutive equations of the model are solved analytically with the help of given boundary conditions to get different expression for flow rate. flow resistance and wall shear stress. It ix observed that the flow rate decreases with stenosis size. It has been shown that the resistance to flow and wall shear stress increases with the size of stenosis, but these increases is comparatively small due to Non-Newtonian type of blood and also comparison of these flow paraneters has been done for linear and quadratic variation of viscosity. [ABSTRACT FROM AUTHOR]

One of the structures for regulating the water level in the irrigation and drainage ducts is the lopac gates, which are proposed as a structure for regulating and controlling the flow level. In this study, a new design of this type of structure has been proposed in which the gates are placed next to each other in pairs, and they are called multiple lopac gates. The objective of this research is to investigate the effective hydraulic parameters of the proposed structure and compare it in a case where a gate is used under the same conditions. All the simulations were modeled with 3 amounts of opening 30, 45, and 60 degrees and at 3 flow rates of 20, 40, and 60 liters per second and using Flow3d software, in these simulations, the number of mesh cells is 1000000 and RNG turbulence model is used. The results showed that the maximum shear stress was reduced by an average of 38% compared to the single gate mode in most tests at different openings and flow rates using multiple lopac gates, and the largest amount of this reduction was related to the opening of 45 degrees, and the flow rate is 40 liters per second with a value of 76%. Also, the forces acting on the gate at different flow rates and openings will be reduced by 150% on average. In the qualitative investigation of flow vortices, the investigations also showed that vortex range, length, and strength are reduced compared to the single gate mode when two gates are used, and the number of vortices increases compared to when a single valve. [ABSTRACT FROM AUTHOR]

Paxillin communicates with multiple signalling molecules in focal adhesions (FAs) and participates in the intracellular force transmission upon shear stress. Thus, paxillin is likely to contribute to establishing the shear stress induced-cell polarity. However, it is still unclear whether the tension across FAs proteins can direct the polarity establishments by providing spatial features, due to a lack of efficient manners. This work proposes a visualization approach containing a DNA-encoded biosensor and fluorescent image processing algorithm to collect the spatiotemporal features of tension across paxillin. The results indicate that the tension across paxillin shows polarity between the upstream and downstream zones of the cell along the direction of shear stress, which was mediated by the membrane fluidity and integrity of the cytoskeleton. It demonstrates that the spatial information from the upper surface of cells upon shear stress can be transmitted to the interior of FAs on the basal layer by the architecture consisting of plasma membrane and cytoskeleton. Paxillin is a potential participant in activating cell polarity by providing a spatial mechanical guide to related signaling molecules upon shear stress. Highlight: • Tension across paxillin polarized upon shear stress depending on the cytoskeleton and membrane fluidity. [ABSTRACT FROM AUTHOR]

The formation of sheet metal products is now widely utilized for multi-purposes in the automotive, aerospace and in industrial sectors. In this study, the phenomenon of plastic strain, von Mises stress, shear train by the V-bending method and to analyze the results theoretically, by using a special program called ANSYS. The multi-layer sheet metal in the rectangular plate of Al and Cu with three different thicknesses (1.0, 1.25, and 1.5 mm) is carried out by the Explicit solver. These parameters have been investigated such as effect sheet setting condition (Al/Cu/Al and Cu/Al/Cu), sheet thickness, and traveling of punch. In the explicit analysis, the position of Al/Cu/Al achieved maximum plastic strain in maximum thickness and punch travel is improved to save computation duration at cost of solution accuracy. Also, maximum shear stress obtained in larger punch travel in position Al/Cu/Al than Cu/Al/Cu. As the thickness is increased, the shear stress and von Mises stress becomes increases in Al/Cu/Al, and position of Cu/Al/Cu produced decreasing shear stress and von Mises stress in increasing sheet thickness with different punch travel. [ABSTRACT FROM AUTHOR]

Excessive flow turbulence poses a threat to the development of drifting fish eggs, leading to mortality or developmental malformations and ultimately depleting early fish resources. Currently, there is a scarcity of quantitative studies investigating the effects of flow turbulence on the entire process of drifting fish egg development, from fertilized egg division to hatching. In this paper, the effects of different flow turbulence conditions (FTCs), including turbulent kinetic energy and shear stress, and action times on different stages of fish egg development were quantitatively explored using a transverse-oscillating-grids turbulence tank. Empirical formulas were established to predict the proportion of normal fish egg development under different FTCs within a selected range. The research findings provide a quantitative basis for protecting early fish resources, mitigating the biological invasion of specific fish, constructing fish-breeding facilities, and ensuring safe transfer and transportation. [ABSTRACT FROM AUTHOR]

Endothelium-dependent vasodilation can be tested using a variety of shear stress paradigms, some of which may involve the production of reactive oxygen species. The purpose of this study was to compare different methods for assessing endothelial function and their specific involvement of reactive oxygen species and influence of aerobic training status. Twenty-nine (10 F) young and healthy participants (VO2max: 34–74 mL·kg−1·min−1) consumed either an antioxidant cocktail (AOC; vitamin C, vitamin E, α-lipoic acid) or placebo (PLA) on each of two randomized visits. Endothelial function was measured via three different brachial artery flow-mediated dilation (FMD) tests: reactive hyperemia (RH-FMD: 5 min cuff occlusion and release), sustained shear (SS-FMD: 6 min rhythmic handgrip), and progressive sustained shear (P-SS-FMD: three intensities of 3 min of rhythmic handgrip). Baseline artery diameter decreased (all tests: 3.8 ± 0.5 to 3.7 ± 0.6 mm, p = 0.004), and shear rate stimulus increased (during RH-FMD test, p = 0.021; during SS-FMD test, p = 0.36; during P-SS-FMD test, p = 0.046) following antioxidant consumption. However, there was no difference in FMD following AOC consumption (RH-FMD, PLA: 8.1 ± 2.6%, AOC: 8.2 ± 3.5%, p = 0.92; SS-FMD, PLA: 6.9 ± 3.9%, AOC: 7.8 ± 5.2%, p = 0.15) or FMD per shear rate slope (P-SS-FMD: PLA: 0.0039 ± 0.0035 mm·s−1, AOC: 0.0032 ± 0.0017 mm·s−1, p = 0.28) and this was not influenced by training status/fitness (all p > 0.60). Allometric scaling did not alter these outcomes (all p > 0.40). Reactive oxygen species may not be integral to endothelium-dependent vasodilation tested using reactive, sustained, or progressive shear protocols in young males and females, regardless of fitness level. [ABSTRACT FROM AUTHOR]

We sought to assess the accuracy of a novel parameter proportional to the rod shear stress (RSS) in identifying patients at risk of rod fracture (RF) after surgery for correction of adult spinal deformity. We performed a retrospective medical record review of patients aged ≥18 years treated for adult spinal deformity between 2004 and 2014 with ≥24 months of follow-up. The primary outcome was RFs identified radiographically. Patient weight (w), number of instrumented levels (N), and minimum rod diameter (d) were recorded and used to calculate the RSS parameter (R S S = N w d 2 ). Receiver operating characteristic curves were produced and the area under the curve (AUC ± 95% confidence interval [CI]) was calculated to compare this parameter's discriminative accuracy to that of its constituent variables. The sensitivity, specificity, and likelihood ratios (LRs) were calculated. A total of 28 RF-positive and 154 RF-negative patients were included. The average age was 59.2 ± 9.6 years, and 93.4% were women. The RSS parameter produced the greatest AUC (0.73 ± 0.11). At an RSS cutoff of 30.1, it achieved a sensitivity of 71.4% and specificity of 71.4% (LR, 2.5; 95% CI, 1.8–3.5). The number of instrumented levels produced the next-greatest AUC (0.65 ± 0.12), with a sensitivity of 78.6% and specificity of 50.0% at a cutoff of 15 (LR, 1.6; 95% CI, 1.2–2.0). The RSS is calculated using easily obtainable information and shows potential as a tool for predicting patient-specific risk of RF after spinal fusion. The number of instrumented levels also correlates strongly with the occurrence of RFs and is not significantly less accurate than the RSS. A larger sample size and prospective validation would be useful in determining with greater confidence which parameter is superior for predicting RFs after spinal fusion. [ABSTRACT FROM AUTHOR]

Intracellular signaling mechanisms in red blood cells (RBCs) involve various protein kinases and phosphatases and enable rapid adaptive responses to hypoxia, metabolic requirements, oxidative stress, or shear stress by regulating the physiological properties of the cell. Protein phosphorylation is a ubiquitous mechanism for intracellular signal transduction, volume regulation, and cytoskeletal organization in RBCs. Spectrin‐based cytoskeleton connects integral membrane proteins, band 3 and glycophorin C to junctional proteins, ankyrin and Protein 4.1. Phosphorylation leads to a conformational change in the protein structure, weakening the interactions between proteins in the cytoskeletal network that confers a more flexible nature for the RBC membrane. The structural organization of the membrane and the cytoskeleton determines RBC deformability that allows cells to change their ability to deform under shear stress to pass through narrow capillaries. The shear stress sensing mechanisms and oxygenation‐deoxygenation transitions regulate cell volume and mechanical properties of the membrane through the activation of ion transporters and specific phosphorylation events mediated by signal transduction. In this review, we summarize the roles of Protein kinase C, cAMP‐Protein kinase A, cGMP‐nitric oxide, RhoGTPase, and MAP/ERK pathways in the modulation of RBC deformability in both healthy and disease states. We emphasize that targeting signaling elements may be a therapeutic strategy for the treatment of hemoglobinopathies or channelopathies. We expect the present review will provide additional insights into RBC responses to shear stress and hypoxia via signaling mechanisms and shed light on the current and novel treatment options for pathophysiological conditions. [ABSTRACT FROM AUTHOR]

Nanocomposite grease was created to reduce wear and friction on surfaces and enhance thermal conductivity. The tribological and rheological properties of nano grease were studied. Calcium grease with varied doses of hybrid TiO2/CNTs/GNs (0.5, 1, 2, 3 wt.%) was prepared. Transmission electron microscope (TEM) was applied to look at the microstructure of nano grease. Tribological and rheological properties of the nano grease were examined by using a four-ball tester. Wear scar diameter (WSD) was reduced by 30% at the optimal TiO2/CNTs/GNs concentration of 2% before beginning to rise. As TiO2/CNTs/GNs are applied in concentrations ranging from 0 to 2 wt.%, the friction coefficient of nano additive containing calcium grease steadily declines. At 2% concentration, the reduction in coefficient of friction was 45% about base grease. The friction coefficient was increased after that to 3 wt.%. Shear rate was reduced when the dose of TiO2/CNTs/GNs was increased. As the concentration of nanomaterials and shear rate increased, so did the viscosity of nano grease. Shear stress and apparent viscosity of the calcium grease containing 3% by weight of TiO2/CNTs/GNs are 43% higher than pure calcium grease, although they are still much lower than pure grease. The inclusion of the nanomaterial causes a roughly 19.5% increase in the dropping point of base grease. The thermal conductivity of nano grease is significantly improved by nano additives, increasing by around 130%, and the additives have a dramatic linear growth on the thermal conductivity of nano grease. [ABSTRACT FROM AUTHOR]

Endothelial cells in steady laminar flow assume a healthy, quiescent phenotype, while endothelial cells in oscillating disturbed flow become dysfunctional. Since endothelial dysfunction leads to atherosclerosis and cardiovascular disease, it is important to understand the mechanisms by which endothelial cells change their function in varied flow environments. Endothelial metabolism has recently been proven a powerful tool to regulate vascular function. Endothelial cells generate most of their energy from glycolysis, and steady laminar flow may reduce endothelial glycolytic flux. We hypothesized that steady laminar but not oscillating disturbed flow would reduce glycolytic flux and alter glycolytic side branch pathways. In this study, we exposed human umbilical vein endothelial cells to static culture, steady laminar flow (20 dynes/cm2 shear stress), or oscillating disturbed flow (4 ± 6 dynes/cm2 shear stress) for 24 h using a cone-and-plate device. We then measured glucose and lactate uptake and secretion, respectively, and glycolytic metabolites. Finally, we explored changes in the expression and protein levels of endothelial glycolytic enzymes. Our data show that endothelial cells in steady laminar flow had decreased glucose uptake and 13C labeling of glycolytic metabolites while cells in oscillating disturbed flow did not. Steady laminar flow did not significantly change glycolytic enzyme gene or protein expression, suggesting that glycolysis may be altered through enzyme activity. Flow also modulated glycolytic side branch pathways involved in proteoglycan and glycosaminoglycan synthesis, as well as oxidative stress. These flow-induced changes in endothelial glucose metabolism may impact the atheroprone endothelial phenotype in oscillating disturbed flow. [ABSTRACT FROM AUTHOR]

Stereolithography technology shows great potential for manufacturing ceramic parts with complex structures. However, it seems difficult to achieve both high forming accuracy and speed. Excess cured areas caused by light scattering is one of the main reasons for the degradation of accuracy. This paper presents a special strategy to remove the excess cured areas by utilizing the shear stress that is generated during the forming process. By adjusting the feeding speed, feeding height, feeding temperature and their combinations, the shear stress can be controlled to be beneficial. The relative forming error greatly decreased by 51.66% for small features. As the feeding speed was increased to 3 or 4 times, the forming accuracy of the structures on different surfaces was increased to 9 times or 2.8 times. This work provides a simple, general and low-cost method for rapid and high-accuracy manufacturing of ceramic parts, especially for those with small structural features. [ABSTRACT FROM AUTHOR]