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Abstract We propose a simple tool for liquid static culture using a copolymer film with high gas permeability. The film bags were successfully used to culture microorganisms Escherichia coli, Komagataella phaffii (methylotrophic) and Bacillus sp. (biofilm-forming), with cells cultured under physical stress-free conditions with sufficient oxygen supply. Similar growth curves and plasmid productivity were observed for liquid shake and film bag E. coli cultures. The early growth response of the film bag culture following colony inoculation of liquid media differed from conventional shake cultures. Our results indicate that a gas-permeable film bag is a promising liquid culture tool and provides novel microbiology materials.

Abstract 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) treadmill test followed by three randomized study visits: treadmill exercise at 30% of V̇O2max for 30 min, 70% of V̇O2max for 30 min and 70% of V̇O2max for a duration that resulted in caloric expenditure equal to that in the 30% V̇O2max 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 (∆4.1 ± 3.5 dyn/cm2) compared with 30% V̇O2max (∆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 (Δ268 ± 150 mL/min) compared with 30% V̇O2max (∆125 ± 149 mL/min; P = 0.041) or 70% V̇O2max 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.

To reveal the mechanism of shear failure of en-echelon joints under cyclic loading, such as during earthquakes, we conducted a series of cyclic shear tests of en-echelon joints under constant normal stiffness (CNS) conditions. We analyzed the evolution of shear stress, normal stress, stress path, dilatancy characteristics, and friction coefficient and revealed the failure mechanisms of en-echelon joints at different angles. The results show that the cyclic shear behavior of the en-echelon joints is closely related to the joint angle, with the shear strength at a positive angle exceeding that at a negative angle during shear cycles. As the number of cycles increases, the shear strength decreases rapidly, and the difference between the varying angles gradually decreases. Dilation occurs in the early shear cycles (1 and 2), while contraction is the main feature in later cycles (3−10). The friction coefficient decreases with the number of cycles and exhibits a more significant sensitivity to joint angles than shear cycles. The joint angle determines the asperities on the rupture surfaces and the block size, and thus determines the subsequent shear failure mode (block crushing and asperity degradation). At positive angles, block size is more greater and asperities on the rupture surface are smaller than at nonpositive angles. Therefore, the cyclic shear behavior is controlled by block crushing at positive angles and asperity degradation at negative angles.

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.

[Objective] This study was aimed at exploring the influence of nearsurface coverage formed by the collapse of flexible vegetation in reducing runoff and erosion yield, and in modulating the hydraulic properties of surface runoff. [Methods] Based on fundamental principles of fluid mechanics and hydraulics, the erosion patterns and hydrodynamic characteristics under lodged flexible vegetation were systemically investigated through indoor hydrodynamic experiments across five levels of coverage, five slope gradients, and three flow rates. [Results] (1) The distribution of erosion volume demonstrated an initial increase followed by a decrease with the increment of slope angle, with the influence of flow rate on the erosion process being more pronounced at steeper slopes. (2) Corresponding to an increase in the coverage of flexible vegetation, and taking 50% coverage as a threshold, the erosion volume generally exhibited a trend of initial reduction followed by an increase. (3) The average flow velocity (v) decreased with increasing vegetative coverage, with the rate of decline becoming gradual as coverage intensified. The variation in Froude number (Fr) mirrored the trend in average flow velocity. The friction coefficient (f) was positively linear correlated with coverage and decreased with an increase in slope gradient; the Reynolds number (Re) demonstrated a higher sensitivity to soil erosion compared to Fr, v, and f. (4) With the increase in vegetation coverage, morphological shear stress intensified (while particle shear stress diminished), playing a pivotal role in the changes in total shear stress, which was positively correlated with vegetation coverage. [Conclusion] The study establishes a solid theoretical foundation for the erosion patterns of slope flow vegetation and facilitates the expansion of open channel hydraulic theories in the realm of slope flows.

In vitro models of kidneys have limited effectiveness owing to the complex structure and functions of the kidney when compared with other organs. Therefore many renal function evaluations are currently being carried out through animal experiments. In contrast, efforts are being made to apply biomimetic systems, such as organ-on-a-chip, which is based on microfluidic device technology, to serve as an in vitro model for the kidney. These systems aimed to recreate a physiological cultivation environment. This review has provided an overview of organ-on-a-chip research focused on glomeruli and tubules as in vitro models for the kidney and discusses future prospects.

PURPOSE Laminar blood flow is known to play a critical role in maintaining endothelial homeostasis in blood vessels. It exerts a shear stress on the endothelial cells (ECs), which is essential for the regulation of various vascular functions. In this study, the effects of laminar blood flow-induced enhanced endothelial homeostasis on the maintenance of vascular function were investigated. METHODS Human umbilical vein endothelial cells (HUVECs) were employed to study gene expression associated with vessel dilation and angiogenesis in response to varying shear stress levels. To assess angiogenesis, experimental mice participated in voluntary wheel running for 16 weeks. To evaluate the vascular autophagic function, the six weeks old C57BL/6 mice underwent an hour of forced treadmill running for 10 weeks. The resulting gene expression was evaluated through western blotting and quantitative real-time polymerase chain reaction (qRT-PCR). RESULTS Disturbed flow resulting from partial ligation surgery in the mice's carotid artery led to a decrease in angiogenic capacity compared to the laminar flow observed in ex vivo sprouting assays. Cultured HUVECs exhibited a significant increase in VEGF expression when exposed to increased durations of 20 dyne/cm² laminar shear stress (LSS). Following a 10-week treadmill exercise regimen, ECs in the carotid arteries of mice showed a significant increase in the expression of autophagic genes, such as LC3II, Atg3, and Atg7, which was not observed in smooth muscle cells (SMCs). LSS was found to boost the expression of both total and phosphorylated eNOS, genes involved in vascular dilation regulation, specifically in ECs. CONCLUSIONS These findings suggest that laminar blood flow sustains vascular function, such as angiogenic capacity, through the enhancement of endothelial homeostasis.

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.

Metal fatigue is a problem in the use of metals in their applications, especially when they are exposed to cyclic or repetitive loads. This study analyzes the effect of round, rectangular and spherical cross-sections on fatigue failure of ST 60 steel. By providing a fatigue test load of 150 N and a rotating speed of 1500 rpm and a test specimen installation position with a distance of 70 cm, it was found that the round cross-section broke when experiencing 26,471 cycles, the rectangular cross-sectional shape broke when experiencing 115,515 cycles and the hollow round shape broke when experiencing 201,983 cycles. The largest shear stress is generated by a spherical cross-section with a value of 247.7 N/mm2 and the lowest is by a material with a hollow spherical cross-section with a value of 194.478 N/mm2. Normal stress and the highest shear stress are produced specimens with a spherical cross-sectional shape, this is because the spherical cross-section has a tendency to spread normal stress evenly over its surface.

Endothelial shear stress is a tangential stress derived from the friction of the flowing blood on the endothelial surface of the arterial wall and is expressed in units of force/unit area (dyne/cm2). Branches and bends of arteries are exposed to complex blood flow patterns that generate low or oscillatory endothelial shear stress, which impairs glycocalyx integrity, cytoskeleton arrangement and endothelial junctions (adherens junctions, tight junctions, gap junctions), thus increasing endothelial permeability. The lipoproteins and inflammatory cells penetrating intima due to the increased endothelial permeability characterizes the pathological changes in early stage of atherosclerosis. Endothelial cells are critical sensors of shear stress, however, the mechanisms by which the complex shear stress regulate endothelial permeability in atherosclerosis remain unclear. In this review, we focus on the molecular mechanisms of the endothelial permeability induced by low or oscillatory shear stress, which will shed a novel sight in early stage of atherosclerosis.

This work presents a theoretical analysis of the non-linear behavior of blood flow along an angled arterial section with overlapping stenosis. An elastic cylindrical tube with a moving wall is used to represent the artery, and a Casson liquid is used to simulate blood flowing through it. The nonlinear equations that govern blood flow are taken into account. The influence of the pulsatile pressure gradient caused by the regular heartbeat on the flow process in the stenosed artery is demonstrated mathematically. The current analytical method can compute the wall shear stress, flow resistivity, and velocity profiles with mild stenosis assumption by applying the boundary conditions. Numerical calculations of the desired quantities are carried out systematically. They provide an overview of how the degree of stenosis and the malleability of the artery wall influence blood flow abnormalities. Concerning the height of stenosis, the surface shear stress and the resistivity to flow increase together with an increase in the proclivity angle.

The development of supportable, cost-effective, and high-performance nanoparticles (NPs) is one of the new examination points within penetrating applications. The consideration of tailorable nanoparticles offers the chance to figure out water-based drilling fluids (WBDFs) with upgraded properties, providing exceptional opportunities in the energy, oil, gas, water, or framework enterprises. In WBDFs, nano and micron materials are investigated to control their rheological properties and their influence. This paper aims to analyze the influence of nano Fe2O3 on the rheological behavior of drilling fluid muds under high temperatures and pressure. Additionally, we seek to identify the optimal concentration of iron oxide nanoparticles that maintain consistent rheology; we examined the interfering effects of shear rates and iron oxide nanoparticle temperature on the shear type of the changed depleting liquid in the Dibella oil field to make the penetrating activity efficient, realistic, and skilled. We observe that as the temperature increases, the water-based mud (WBM), plastic viscosity (PV), yield point (YP), and gel strength (Gs) decrease until the reject structure is disrupted. Therefore, we must proceed with our assessment using nano Fe2O3 to resolve the shortcomings of the slope framework. Six water-based mud cakes containing 0.5, 1, 1.5, 2, 2.5, and 3 g weight percent of iron oxide (Fe2O3) nanoparticles were prepared for this evaluation. The experimental outcomes revealed an optimal nanoparticle mixing of 2.5 g weight percent, which resulted in a 13.8% reduction in the API filtrate volume and a 40% reduction in filter cake thickness. At 300°F temperature and type 10.00 pressure, the results of our experiments consistently demonstrate a decrease of 14.77% in the rheological properties of PV and YP and 10 s and 10 min in the gel strength of carbon oxide nanoparticles. The YP–PV span is 2.7, and the yield strength is 11 lb/100 ft2. On the other hand, mud cake A, which contains 0.5 wt% NPs, loses 6 mL of fluid after 30 min. In contrast, drilling mud cake E, which is composed of 3 wt% NPs, shows a fluid loss of 5.1 mL in the API filter press test. Based on the Bingham plastic model, the maximum shear stress versus shear rate was observed for bentonite drilling muds E and F, with 2.5 wt% and 3 wt% NPs, respectively, and this result indicates that the use of nano Fe2O3 can effectively adjust the properties of drilling fluids.

The entry and propagation of pores inside an adhesive interface between an elastomer and a rigid sphere were studied experimentally and simulated numerically. It was shown that mutually interacting events involving attachment–detachment of different segments of the elastomer to the indenter resulted in non-trivial patterns of spatially distributed contacts between them, which were additionally influenced by air penetration of the pores.

The efficacy of a sanitizer in biofilm removal may be influenced by a combination of factors such as sanitizer exposure time and concentration, bacterial species, surface topography, and shear stresses. We employed an inline biofilm reactor to investigate the interactions of these variables on biofilm removal with chlorine. The CDC bioreactor was used to grow E. coli O157:H7 and L. monocytogenes biofilms as a single species or with Ralstonia insidiosa as a dual-species biofilm on stainless steel, PTFE, and EPDM coupons at shear stresses 0.368 and 2.462 N/m2 for 48 hours. Coupons were retrieved from a CDC bioreactor and placed in an inline biofilm reactor and 100, 200, or 500 ppm of chlorine was supplied for 1- and 4 min. Bacterial populations in the biofilms were quantified pre- and posttreatment by plating on selective media. After chlorine treatment, reduction (Log CFU/cm2) in pathogen populations obtained from three replicates was analyzed for statistical significance. A 1-min chlorine treatment (500 ppm), on dual-species E. coli O157:H7 biofilms grown at high shear stress of 2.462 N/m2 resulted in significant E. coli O157:H7 reductions on SS 316L (2.79 log CFU/cm2) and PTFE (1.76 log CFU/cm2). Similar trend was also observed for biofilm removal after a 4-min chlorine treatment. Single species E. coli O157:H7 biofilms exhibited higher resistance to chlorine when biofilms were developed at high shear stress. The effect of chlorine in L. monocytogenes removal from dual-species biofilms was dependent primarily on the shear stress at which they were formed rather than the surface topography of materials. Besides surface topography, shear stresses at which biofilms were formed also influenced the effect of sanitizer. The removal of E. coli O157:H7 biofilms from EPDM material may require critical interventions due to difficulty in removing this pathogen. The inline biofilm reactor is a novel tool to evaluate the efficacy of a sanitizer in bacterial biofilm removal.

Abstract To reduce the trend of scouring, understanding the flow pattern around the bridge piers is necessary. By using hydraulic structures such as submerged vanes, it is possible to alter the flow pattern of water, thus scouring process and sediment transport in riverbeds. Since the scouring mechanism for pier groups differs from single pier, experiments were conducted in a 180° sharp bend channel in the laboratory to investigate the flow pattern around pier group and single pier under the influence of 25% submerged vanes. Furthermore, a comparison was made between the flow patterns in single pier and pier group conditions. Three-dimensional velocities along the bend and different depths were measured using an Acoustic Doppler Velocimeter (ADV(. The results suggest that the maximum vorticity value at the apex position of the bend (location of piers) and the maximum secondary flow value, at the distance between the piers and the vanes, were found to be, 0.15 and 0.89, respectively. In the twin pier experiment, the maximum Reynolds shear stress value $${\tau }_{yx}$$ τ yx decreased by about 36%, and the minimum value decreased by about 49% compared to the single pier experiment. The final results indicated that using submerged vanes obtained the maximum $${\tau }_{yx}$$ τ yx and $${\tau }_{zx}$$ τ zx near the vanes. Near the bed and mid-depth of the water flow, the geometric location of the maximum velocity also occurred around the vanes in both experiments. Therefore, the vanes are important in altering the water flow pattern, diverting the flow from around piers and consequently reducing the bridge pier scouring.

The ex vivo production of platelets from induced pluripotent cells (iPSCs) may offer a safer and sustainable alternative for transfusions and drug delivery systems (DDS). However, the mass production of the clinically required number of iPSC-derived platelets (iPSC-PLTs) is challenging. Here, we introduce recent technologies for mass production and the first-in-human clinical trial using ex vivo iPSC-PLTs. To this end, we established immortalized megakaryocyte progenitor cell lines (imMKCLs) as an expandable master cell bank (MCB) through the overexpression of c-MYC, BMI1 and BCL-XL, which modulated megakaryopoiesis and thrombopoiesis. We also optimized a culture cocktail for maturation of the imMKCLs by mixing an aryl hydrocarbon receptor (AhR) antagonist, SR1/GNF-316; a Rho-associated protein kinase (ROCK) inhibitor, Y-27632/Y-39983; and a small-molecule compound replacing recombinant thrombopoietin (TPO), TA-316. Finally, we discovered the importance of turbulence on the manufacturing of intact iPSC-PLTs, allowing us to develop a turbulence-based bioreactor, VerMES. Combination of the MCB and VerMES enabled us to produce more than 100 billion iPSC-PLTs, leading to the first-in-human clinical trial. Despite these advancements, many challenges remain before expanding the clinical implementation of this strategy.

Abstract Asphalt overlay is widely used in maintaining and rehabilitating highway system performance. However, explicit calculation methods for the asphalt overlay thickness range is lacking. Taking stone mastic asphalt (SMA) and asphalt concrete (AC) asphalt overlay on cement concrete pavement as examples, the paper proposed a design method for the asphalt overlay thickness range based on the shear performance of the interlayer. Firstly, the shear stress distribution regularities on the asphalt overlay and Portland cement concrete interlayer was calculated with a multilayer elastic theory. Meanwhile, the shear strength was obtained from a series of direct shear tests. The shear characters of the asphalt overlay met with the Mohr–Coulomb criterion, and the shear strength parameters cohesive force $$c$$ c and interface friction angle $$\varphi$$ φ on the interlayer were acquired. Finally, a method for determining the thickness range of double layer asphalt overlay under different traffic conditions was given. The epoxy resin adhesive was recommended for the highway with severe local premature shear failure compared with the modified emulsion asphalt. Therefore, through the above research, the amount of asphalt used is controlled in a reasonable range, thus improving the pavement structure durability and reducing energy consumption.

Extrusion-based 3D bioprinting has revolutionised tissue engineering, enabling complex biostructure manufacturing. However, extrusion imposes substantial shear stress on cells, compromising cell viability. Predicting and optimising cell viability remains challenging due to rheological modelling complexity and cell-type dependency. To address these challenges, this study developed a quantitative framework integrating numerical simulation and machine learning. Support vector regression and simulation were utilised to evaluate alginate ink viscosity and shear stress profiles, while multi-layer perceptron regressors were trained on experimental datasets for diverse cell types to predict as-extruded cell viability based on wall shear stress magnitude and exposure time. Results showed vascular endothelial cells were most susceptible to shear stress, with viability dropping to 80% at 2.05 kPa for 400 ms, while mesenchymal stem, cervical cancer, and embryonic fibroblast cells showed such decrease at 2.65, 2.85, and 3.72 kPa, respectively. This versatile framework enables rapid bioink optimisation across various cell types.

The impact of the biophysical environment on the platelet storage lesion (PSL) has mainly focused on reduced temperature storage, overlooking the significance of storage-induced shear stress. Shear stress in platelet storage refers to the frictional force acting parallel to the bag surface and exists solely through the implementation of agitation. This study investigates whether minimizing exposure to agitation-induced shear stress can alleviate the unexplained loss of function in stored platelet concentrates for neonatal transfusion (neonatal PCs). Using particle tracking analysis, fluid motion was measured in neonatal and adult platelet storage bags under agitation frequencies ranging from 20–60 rpm. Platelets stored at 20-60 rpm agitation over 8 days were examined by biochemical analysis, aggregation, and expression of activation markers. Results indicate that neonatal PCs experience significantly higher storage-induced shear stress compared to adult doses, leading to reduced functionality and increased activation from day 2 of storage. Adjusting the neonatal PC agitation frequency to 20 rpm improved functionality in early storage, while 40 rpm maintains this improvement throughout storage with reduced activation, compared to 60 rpm storage. This study confirms that small volume PC storage for neonatal use contributes to the PSL through the induction of shear stress, suggesting further evaluation of the recommended agitation frequency for neonatal PCs or postponement of the production of neonatal PCs until requested for neonatal transfusion.

AbstractConcrete-filled steel tubes (CFSTs) have demonstrated superior performance compared to other types of composite columns. The evaluation of interactions between concrete and steel composites is crucial due to their significant impact on the overall structural behavior in various loadings. This study develops an artificial neural network (ANN) that predicts the ultimate interfacial bond strength ([Formula: see text]) of circular and square CFSTs. The length of the interfacial bond between the tube and the concrete; the thickness, shape, and inner perimeter of the tube; and the cubic compression strength and age of the concrete are considered as model inputs. The modeling process uses 397 experimental datasets from 18 studies of push-out tests, more specifically, 143 square and 254 circular CFSTs. ANN with a hidden layer of error-propagation, feed-forward, and sigmoidal activation function is trained, tested, optimized, and validated to achieve a good estimate. The resulting model can predict the [Formula: see text] with a satisfactory coefficient of determination (R2) of 0.87. The ability of the developed model to predict the [Formula: see text] is compared to the proposed formulas in the literature. It is found that the ANN model provides the most accurate predictions among all suggested formulas, in terms of R2 and Taylor diagram analyses. Furthermore, the inclusion of the shape factor enabled the ANN model to predict the [Formula: see text] of both squared and circular shapes of CFSTs. The validated ANN model is then used to examine the sensitivity of the parameters to the [Formula: see text] The correlations agreed well with the expected trend of published studies.

The luminal surface of the endothelium is exposed to dynamic blood flow patterns that are known to affect endothelial cell phenotype. While many studies have documented the phenotypic changes by gene or protein expression, less is known about the role of blood flow pattern on the endothelial cell (EC) lipidome. In this study, shotgun lipidomics was conducted on human aortic ECs (HAECs) exposed to unidirectional laminar flow (UF), disturbed flow (DF), or static conditions for 48 h. A total of 520 individual lipid species from 17 lipid subclasses were detected. Total lipid abundance was significantly increased for HAECs exposed to DF compared to UF conditions. Despite the increase in the total lipid abundance, HAECs maintained equivalent composition of each lipid subclass (% of total lipid) under DF and UF. However, by lipid composition (% of total subclass), 28 lipid species were significantly altered between DF and UF. Complimentary RNA sequencing of HAECs exposed to UF or DF revealed changes in transcripts involved in lipid metabolism. Shotgun lipidomics was also performed on HAECs exposed to pro-inflammatory agonists lipopolysaccharide (LPS) or Pam3CSK4 (Pam3) for 48 h. Exposure to LPS or Pam3 reshaped the EC lipidome in both unique and overlapping ways. In conclusion, exposure to flow alters the EC lipidome and ECs undergo stimulus-specific lipid reprogramming in response to pro-inflammatory agonist exposure. Ultimately, this work provides a resource to profile the transcriptional and lipidomic changes that occur in response to applied flow that can be accessed by the vascular biology community to further dissect and extend our understanding of endothelial lipid biology.

Proximal tubule (PT) cells maintain a high-capacity apical endocytic pathway to recover essentially all proteins that escape the glomerular filtration barrier. The multi ligand receptors megalin and cubilin play pivotal roles in the endocytic uptake of normally filtered proteins in PT cells but also contribute to the uptake of nephrotoxic drugs, including aminoglycosides. We previously demonstrated that opossum kidney (OK) cells cultured under continuous fluid shear stress (FSS) are superior to cells cultured under static conditions in recapitulating essential functional properties of PT cells in vivo. To identify drivers of the high-capacity, efficient endocytic pathway in the PT, we compared FSS-cultured OK cells with less endocytically active static-cultured OK cells. Megalin and cubilin expression are increased, and endocytic uptake of albumin in FSS-cultured cells is > 5-fold higher compared with cells cultured under static conditions. To understand how differences in receptor expression, distribution, and trafficking rates contribute to increased uptake, we used biochemical, morphological, and mathematical modeling approaches to compare megalin traffic in FSS- versus static-cultured OK cells. Our model predicts that culturing cells under FSS increases the rates of all steps in megalin trafficking. Importantly, the model explains why, despite seemingly counterintuitive observations (a reduced fraction of megalin at the cell surface, higher colocalization with lysosomes, and a shorter half-life of surface-tagged megalin in FSS-cultured cells), uptake of albumin is dramatically increased compared with static-grown cells. We also show that FSS-cultured OK cells more accurately exhibit the mechanisms that mediate uptake of nephrotoxic drugs in vivo compared with static-grown cells. This culture model thus provides a useful platform to understand drug uptake mechanisms, with implications for developing interventions in nephrotoxic injury prevention.

Varicose veins are the most common venous disorder in humans and are characterized by hemodynamic instability due to valvular insufficiency and orthostatic lifestyle factors. It is unclear how changes in biomechanical signals cause aberrant remodeling of the vein wall. Our previous studies suggest that Notch signaling is implicated in varicose vein arterialization. In the arterial system, mechanoresponsive ETS1 is a transcriptional activator of the endothelial Notch, but its involvement in sensing disrupted venous flow and varicose vein formation has not been investigated. Here, we use human varicose veins and cultured human venous endothelial cells to show that disturbed venous shear stress activates ETS1-NOTCH4/DLL4 signaling. Notch components were highly expressed in the neointima, whereas ETS1 was upregulated in all histological layers of varicose veins. In vitro microfluidic flow-based studies demonstrate that even minute changes in venous flow patterns enhance ETS1-NOTCH4/DLL4 signaling. Uniform venous shear stress, albeit an inherently low-flow system, does not induce ETS1 and Notch proteins. ETS1 activation under altered flow was mediated primarily by MEK1/2 and, to a lesser extent, by MEK5 but was independent of p38 MAP kinase. Endothelial cell-specific ETS1 knockdown prevented disturbed flow-induced NOTCH4/DLL4 expression. TK216, an inhibitor of ETS-family, prevented the acquisition of arterial molecular identity and loss of endothelial integrity in cells exposed to the ensuing altered shear stress. We conclude that ETS1 senses blood flow disturbances and may promote venous remodeling by inducing endothelial dysfunction. Targeting ETS1 rather than downstream Notch proteins could be an effective and safe strategy to develop varicose vein therapies.

The objective of this study is to present a new method of reinforcing masonry using layers of mortar reinforced with short jute fibers. Mortars were produced with 0%, 2% and 3% jute fibers with cementitious matrices free of calcium hydroxide. The effectiveness of the reinforced mortar was evaluated through diagonal compression tests of hollow ceramic brick masonry prisms. The prisms were coated on both sides. The experimental results demonstrated that the diagonal resistance of the fiber system increased by 28 to 30% and presented greater resistance to elastic deformation during load application, with deformation coefficients 2 and 3 times greater for 2% and 3% of fibers, respectively. Therefore, jute fibers prove to be a sustainable and efficient alternative for masonry reinforcement applications, with maximum applied loads considerably higher than the unreinforced system, in addition to better crack control.

This study analyzes a concrete dam using Abaqus software at different water storage levels (60m, 70m, and 80m). The dam sections are designed based on these levels using approved equations by the United States Bureau of Reclamation. Static and dynamic forces, including seismic components, are calculated for worst-case scenarios. The analysis considers cases with and without galleries, varying the dam base width. Stresses (vertical, shear, and main) are calculated and presented as curves for comparison. The study examines the impact of reservoir water levels, additional base parts, and galleries on dam stability. Findings show that galleries significantly affect stress distribution, causing stress concentrations near openings. Normal stress is uniform except at the gallery, where it decreases. Maximum water storage leads to slight increases in normal stress. Without a gallery, normal stress increases until a certain distance, then decreases towards the pre-toe region, with maximum stress at the toe. The length of the additional base has a limited effect on normal stress. The presence of a gallery affects principal stress distribution, with higher values near the toe region for higher storage levels. The shear stress distribution is more uniform without a gallery. These findings demonstrate the complex interaction of factors in concrete dam stress behavior. Proper consideration of these factors is crucial for design, analysis, and maintenance to ensure structural integrity and performance. Further analysis considering material properties, loading conditions, and dam geometry would enhance understanding and facilitate precise design and safety assessments.

Abstract Background Von Willebrand factor (VWF) and factor VIII (FVIII) complex play a pivotal role in hemostasis. A deficiency or defect of VWF causes von Willebrand disease (VWD). Recombinant (r)VWF product has proved to be effective for hemostatic treatment of VWD, but limited information is available on their role in moderating thrombus formation under flow condition. We aimed to assess thrombus formation in the presence of rVWF combined with rFVIII or pegylated-extended half-life rFVIII (peg-EHL-rFVIII) in VWD whole blood under high shear flow. Methods Perfusion chamber experiments under high shear (2,500 s− 1) combined with immunostaining were performed using patient’s whole blood with type 1 VWD, mixed with rVWF (Vonvendi®; 1.6 IU/mL), rFVIII or peg-EHL-rFVIII (Advate® or Adynovate®; 1.0 IU/mL), or both. Similar experiments were also conducted with clinical medical devices (T-TAS®). Results The addition of rFVIII did not augment thrombus formation assessed by surface coverage (SC) and thrombus height (TH), whereas rVWF enhanced these parameters (SC 19.1 ± 1.1% vs. 30.1 ± 4.1%, TH 2.2 ± 0.14 μm vs. 3.6 ± 0.40 μm, respectively). The co-presence of rVWF/rFVIII was comparable to plasma-derived VWF/FVIII (Confact®, VWF:FVIII ratio = 1.6:1.0) for increasing thrombogenicity in SC (32.5 ± 4.3% vs. 38.7 ± 5.5%) and in TH (5.0 ± 0.60 μm vs. 5.5 ± 0.64 μm), respectively. The pre-incubation time with rVWF and rFVIII appeared to have a little effect on the size of thrombus. Peg-EHL-rFVIII mediated thrombus formation to similar extent as rFVIII in the co-presence of rVWF. Similar results were obtained even with T-TAS. Immunostaining demonstrated that rFVIII and peg-EHL-rFVIII were similarly co-localized with rVWF in formed thrombi, indicating that pegylation did not interfere with molecular complexes. Conclusion The effects of high-level rVWF and peg-EHL-rFVIII on thrombus formation were comparable to conventional therapeutic products in a patient’s whole blood with VWD under high shear flow.

Stem cells are widely used in scientific research because of their ability to self-renew and differentiate into a variety of specialized cell types needed for body functions. However, the self-renewal and differentiation of stem cells are regulated by various stimuli, with mechanical stimulation being particularly notable due to its ability to mimic the physical environment in the body. This study systematically collected 2638 research papers published between 1994 and 2024, employing tools such as VOSviewer, CiteSpace, and GraphPad Prism to uncover research hotspots, publication trends, and collaboration networks. The results indicate a yearly increase in global research on the shear stress stimulation of stem cells, with significant contributions from the United States and China in terms of research investment and output. Future research directions include a deeper understanding of the mechanisms underlying mechanical stimulation’s effects on stem cell differentiation, the development of new materials and scaffold designs to better replicate the natural cellular environment, and advancements in regenerative medicine. Despite considerable progress, challenges remain in translating basic research findings into clinical applications.

Emerging evidence claims the vascular benefits of varied frequency and duration of physical activity (PA) breaks, whereas the efficacy of varied intensity remains unexplored. We aimed to collate and summate the studies investigating the PA breaks at various intensities on vascular protection. Seven electronic databases were searched for potential studies till Jan 31, 2022. The eligible studies should have administered PA breaks of differing intensities in prolonged sitting postures and explored regional vascular changes [flow mediated dilation (FMD), shear stress, diameter, and blood flow] using ultrasound and novel outcome markers. Two independent reviewers assessed the studies for eligibility after abstract and full-text screen, and appropriate data were extracted to summarise vascular protective effects with PA breaks. Our findings reveal adverse regional vascular outcomes with prolonged sitting (FMD ≈ –1.5%, diameter ≈ –0.06 mm), whereas PA breaks of any intensity were found to improve endothelial functions (FMD ≈ +0.5%, diameter ≈ +0.1 mm, shear ≈ +13 s-1) and mitigate the adverse effects associated with prolonged sitting. Compared with high-intensity activity, low-intensity PA breaks alleviate arterial stiffness and endothelial dysfunction risks.

BackgroundSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for COVID-19, has caused nearly 7 million deaths worldwide. Severe cases are marked by an aggressive inflammatory response known as hypercytokinemia, contributing to endothelial damage. Although vaccination has reduced hospitalizations, hypercytokinemia persists in breakthrough infections, emphasizing the need for disease models mimicking this response. Using a 3D microphysiological system (MPS), we explored the vascular role in SARS-CoV-2-induced hypercytokinemia.MethodsThe vascularized micro-organ (VMO) MPS, consisting of human-derived primary endothelial cells (ECs) and stromal cells within an extracellular matrix, was used to model SARS-CoV-2 infection. A non-replicative pseudotyped virus fused to GFP was employed, allowing visualization of viral entry into human ECs under physiologic flow conditions. Expression of ACE2, TMPRSS2, and AGTR1 was analyzed, and the impact of viral infection on ACE2 expression, vascular inflammation, and vascular morphology was assessed.ResultsThe VMO platform facilitated the study of COVID-19 vasculature infection, revealing that ACE2 expression increased significantly in direct response to shear stress, thereby enhancing susceptibility to infection by pseudotyped SARS-CoV-2. Infected ECs secreted pro-inflammatory cytokines, including IL-6 along with coagulation factors. Cytokines released by infected cells were able to activate downstream, non-infected EC, providing an amplification mechanism for inflammation and coagulopathy.DiscussionOur findings highlight the crucial role of vasculature in COVID-19 pathogenesis, emphasizing the significance of flow-induced ACE2 expression and subsequent inflammatory responses. The VMO provides a valuable tool for studying SARS-CoV-2 infection dynamics and evaluating potential therapeutics.

Waves and currents are responsible for sediment movement around and off coral reefs, affecting reef growth at both geological and modern timescales. Given the wide distribution and limited hydrodynamic information of reefs in the South China Sea, we carried out observations on tidal-cycle hydrodynamics in the Nansha Islands with tripod stationary instruments on the seafloor in order to fill the gap in our understanding of these processes. It was found that the magnitudes of near-bed orbital velocity were comparable with that of the mean tidal current, despite generally calm wave conditions. Waves dominated the combined wave-current skin-friction shear velocities acting on reef sediment, which were significantly higher than those generated by currents alone. Due to the large physical roughness of reef, drag coefficient and hydrodynamic roughness length estimated from logarithmic velocity profiles were two orders of magnitude higher than that in macro-tidal-estuary or inner shelf areas covered with siliceous muds or sands. The combined sinusoidal wave and asymmetric tidal current, along with the physical reef roughness, shaped velocity profile structures in the bottom boundary layer, which exhibited a logarithmic profile during the flood tide and a potential flow during the ebb. In absence of wave breaking, strong turbulence dissipation was observed across the rough reef, promoting strong mixing of water, which is crucial for delivering nutrients for coral growth. These findings imply the need to consider the unique characteristics of rough reef structure and combined effects of waves and currents to model the hydrodynamics in reef environment correctly. This understanding is critical for predicting energy and material transport in reef environments, which is essential for maintaining healthy coral ecosystems, and opens new paths for managing and preserving coral reefs in the face of environmental change.

Abstract Measurements of surface heat flux from boreholes of the NIED Hi‐net network of seismometers are used to determine temperature and shear stress on the plate interface beneath northern Honshu. At the maximum depth of thrust‐faulting earthquakes, about 60 km, the temperature is 660 ± 240°C and the average shear stress during slip on the interface is 100 ± 45 MPa. The equivalent quantities from the oceanic setting of the Kermadec trench are 630 ± 140°C and 115 ± 25 MPa. The shear stresses are substantially higher than commonly assumed in models of convergent plate interfaces, but are consistent with measurements made above other convergent plate interfaces where heat flux data are more sparse. They are also consistent with the level of shear stress required to explain measurements of pressure and temperature from high‐pressure‐low‐temperature terrains that experienced metamorphism on subduction interfaces, in particular those from the Cretaceous Sanbagawa belt of SW Japan.

Objective To determine the effects of main components (Rg1, Re and R1) of Panax notoginseng saponins on platelet activation and aggregation induced by shear stress. Methods A narrow microfluidic chip model was established, and used to evaluate the effects of Rg1, Re and R1 at different concentrations (0.05, 0.1, 0.25 and 0.5 mg/mL) on shear-induced platelet aggregation under different shear rates (1 500, 4 500 and 9 000 s-1). Flow cytometry was used to quantitatively detect the shear-induced platelet activation (P-selectin and PAC-1) after the treatment of Rg1, Re and R1. PL-12 analyzer was performed to measure the effects of Rg1, Re and R1 on platelet aggregation induced by arachidonic acid (AA) and adenosine diphosphate (ADP). Results Rg1, Re and R1 inhibited platelet aggregation induced by high shear stress in a concentration-dependent manner (P < 0.01), but had no such inhibitory effect under lower shear stress. Among the 3 components, Re had the strongest inhibitory effect, and their IC50 value was 0.1, 0.07, and 0.2 mg/mL, respectively. No synergistic effect was observed when the 3 components were used together at the same dose. Rg1, Re and R1 inhibited the expression of P-selectin and PAC-1 (P < 0.01), which was consistent with the results of the aggregation experiment. In addition, the 3 components also could inhibit platelet aggregation induced by AA and ADP. Conclusion The main components of Panax notoginseng saponins exert their antiplatelet activity by inhibiting shear-induced platelet aggregation.

The present study aims to focus the turbulent flow characteristics over arrays of submerged boulders in a gravel bed stream. Round shaped boulders of diameter, Dc = 6 cm were staggered over a gravel bed stream (d50 = 4 cm) with varying boulder-to-boulder spacing and the flows over the arrays were studied experimentally. The flow measurements were carried out by an acoustic Doppler velocimeter and the double averaging methodology (DAM) was applied. The results of large spacing boulder array reveals near-bed velocity deficit within 1Dc upstream to 5Dc downstream of the boulder and no influence on the approaching velocity was observed after 5Dc corroborating the recovery of boundary layer. In case of medium and small spacing boulder array, the velocity deficit is significant at all locations. The shear stress distributions depict development of high and low bed shear stresses causing redistributions of the local bed shear stress. The higher magnitude of shear stress is observed at the boulder crest whereas; the secondary peak near the gravel bed crest is attributed to the skin shear stress on the individual boulder. Moreover, the present research contributes to our understanding that the boulder array on a rough bed stream leads to higher turbulent intensity at the boulder crest level.

A major part of the globe is made up of seas, rivers, underground waters and oceans, and from those places where a major part of the resources needed by humans comes from these methods and requires engineering constructions, coastal protection is important. . being high Development, sustainable, engineering and selection of the best protection method to organize and stabilize the coast, depend on the sea from the sea. Among the protection methods, we can mention coastal wall structures, which reduce the wave height from the beach by creating damping. In the current research, according to the performance of numerical modeling, laboratory results are used to check the efficiency of Open FOAM software and the k-o SST turbulence model in modeling the individual behavior of the body of the coastal Ivar structure. Considering different conditions in modeling, the total number of 10 tests, 5 in the case of coastal wall structure and 5 without structure in 5 different degrees (6, 7.5, 9, 10.5, 12 cm) and the same conditions (structure height 7.5 cm) was chosen to implement the program. The results showed that the forces have increased compared to the state without the structure, in other words, it can be said that the presence of the structure can be compared to the state without the structure in the depreciation of the experimental force. Since the change of forces to the structures is a function of the height, so it decreases with the increase in the amount of influence.

Background: The hemodynamic performance of cardiovascular medical devices and their potential to cause blood damage are critical factors in ensuring patient safety and device efficacy. Computational Fluid Dynamics (CFD) has emerged as a valuable tool for simulating blood flow within these devices and predicting the risk of blood damage.Objective: This study aims to utilize CFD simulations to evaluate the local hemodynamic performance of a particular implantable device and to provide precise predictions about likely adverse clinical effects, cutting-edge techniques like LDA or PIV must be accessible.Methods: A patient-specific CFD model of the cardiovascular system and medical devices was developed based on medical imaging data. Hemodynamic parameters such as shear stress and flow recirculation were computed to identify regions of potential blood damage. The simulations were validated against data.Results: The CFD simulations revealed intricate flow patterns and areas of concern within the medical devices. Elevated shear stresses and prolonged residence times were identified in certain regions, indicating a risk of blood damage (Figure 2). By quantifying these parameters, the study provided a comprehensive assessment of potential blood damage locations and severity levels.Conclusion: Computational Fluid Dynamics proved to be a robust approach for evaluating blood flow within cardiovascular devices and predicting potential blood damage. The study highlighted specific design modifications that could mitigate the risk of blood damage, thus contributing to the improvement of device safety. The integration of CFD with patient-specific data offers clinicians and engineers a powerful tool for optimizing cardiovascular device design and minimizing patient risk.

Background: In recent years, intravascular micro-axial blood pumps have been increasingly used in the treatment of patients with cardiogenic shock. The flow rate of such blood pumps requires adjustment based on the patient’s physiological condition. Compared to a stable flow state with fixed rotation speed, adjusting the speed of blood pump impeller to alter flow rate may lead to additional hemolysis. This study aimed at elucidating the relationship between adjusting interval of a blood pump’s impeller speed and the hemolysis index. Methods: By comparing simulation results with P-Q characteristic curves of the blood pump measured by experiments, the accuracy of the blood pump flow field simulation model was confirmed. In this study, a drainage tube was employed as the device analogous to an intravascular micro-axial blood pump for achieving similar shear stress levels and residence times. The hemolysis finite element prediction method based on a power-law model was validated through hemolysis testing of porcine blood flow through the drainage tube. The validated models were subsequently utilized to investigate the impact of impeller speed adjusting intervals on hemolysis in the blood pump. Results: Compared to steady flow, the results demonstrate that the hemolysis index increased to 6.3% when changing the blood pump flow rate from 2 L/min to 2.5 L/min by adjusting the impeller speed within 0.072 s. Conclusions: An adjustment time of impeller speed longer than 0.072 s can avoid extra hemolysis when adjusting the intravascular micro-axial blood pump flow rate from 2 L/min to 2.5 L/min.

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.

Bacterial adhesion to biotic and abiotic surfaces under fluid shear stress plays a major role in the pathogenesis of infections linked to medical implants and tissues. This study employed an automated BioFlux 200 microfluidic system and video microscopy to conduct real-time adhesion assays, examining the influence of shear stress on adhesion kinetics and spatial distribution of Staphylococcus aureus on glass surfaces. The adhesion rate exhibited a non-linear relationship with shear stress, with notable variations at intermediate levels. Empirical adhesion events were simulated with COMSOL Multiphysics® and Python. Overall, COMSOL accurately predicted the experimental trend of higher rates of bacterial adhesion with decreasing shear stress but poorly characterized the plateauing phenomena observed over time. Python provided a robust mathematical representation of the non-linear relationship between cell concentration, shear stress, and time but its polynomial regression approach was not grounded on theoretical physical concepts. These insights, combined with advancements in AI and machine learning, underscore the potential for synergistic computational techniques to enhance our understanding of bacterial adhesion to surfaces, offering a promising avenue for developing novel therapeutic strategies.

The problem of treating cancer is considered one of the most important daily challenges that affect the lives of people with cancer. This research deals with solving this problem theoretically. Through previous studies, it has been proven that gold nanoparticles are able to remove these cancer cells. The idea of this research is theoretically based on injecting a cancer patient with gold nanoparticles that are exposed to a magnetic field. When these particles penetrate cancerous cells and are exposed to a magnetic field, this causes their temperature to rise. The high temperature of the nanometer gold particles that penetrate the cells of the affected body leads to the explosion of the cancer cells. In this research, the various external forces that affect the flow movement of the nanofluid are studied and how its physical and thermal properties are affected by those external forces. The MHD peristaltic flow of a nanofluid in an annulus pipe as a result of the effect of the wall properties has been investigated. This has been achieved through slip and thermal conditions. Wave velocity u0 leads to flow development. The inner annulus wall is rigid, while the outer wall of the artery moves under the influence of wave peristaltic movement. The nonlinear equations that describe the flow are solved under long-wavelength assumptions. The results were compared with other numerical methods, such as finite volume and finite element and the long wavelength method and proved to be accurate and effective. The expressions of pressure difference, velocity, stream function, wall shear stress, and temperature are analyzed. It is noted that the flow velocity increases with the Knudsen number, and the increased source heat suggests an increased temperature. The increasing amplitude ratio at most of the interface points between the artery wall and the catheter results in increased velocity. The streamlines are affected by the magnetic field, as increasing the influencing magnetic field leads to a decrease in flow lines. It is observed that this stress decreases when nanoparticles increase, in contrast to the effect of the magnetic field and also the occurrence of slipping. It was found that the mass of the wall cells relative to their area works to decrease the pressure difference, in contrast to the tension between those cells, which works to increase the pressure difference. Without slipping Kn=0 and with slipping Kn=0.1, the temperature decreases with increasing in nanoparticle concentration φ. The temperature also increases with the amplitude ratio δ. This strongly affects the generated drag on the catheter wall, which is mainly responsible for the enhanced temperature on this wall.

Sediment erosion around submarine pipelines is a popular topic, widely investigated in both ocean and submarine-pipeline engineering. In this paper, the incompressible smoothed-particle hydrodynamics (ISPH) method is modified for simulation of local scouring process around the submarine pipeline under the action of unidirectional flow. The erosion model is based on the Clear Water Particle–Turbid Water Particle–Critical Shear Stress (CWP-TWP-CSS) concept, and a sand–water two-phase model is proposed to deal with the sediment-entrained flow. The results of the numerical simulation are compared with the experimental data to verify the accuracy and applicability of the numerical model. The scouring process around the pipeline is investigated under different conditions, i.e., pipeline diameters, gap ratios, and flow velocities. The ISPH model is further used to study the flow characteristics of the scour pits around the submarine pipeline and the influence of the vortices on the maximum scour depth, to provide a theoretical basis for the stability design of submarine pipelines.

Human mesenchymal stromal cells (hMSCs) are mechanically sensitive undergoing phenotypic alterations when subjected to shear stress, cell aggregation, and substrate changes encountered in 3D dynamic bioreactor cultures. However, little is known about how bioreactor microenvironment affects the secretion and cargo profiles of hMSC-derived extracellular vesicles (EVs) including the subset, “exosomes”, which contain therapeutic proteins, nucleic acids, and lipids from the parent cells. In this study, bone marrow–derived hMSCs were expanded on 3D Synthemax II microcarriers in the PBS mini 0.1L Vertical-Wheel bioreactor system under variable shear stress levels at 25, 40, and 64 RPM (0.1–0.3 dyn/cm2). The bioreactor system promotes EV secretion from hMSCs by 2.5-fold and upregulates the expression of EV biogenesis markers and glycolysis genes compared to the static 2D culture. The microRNA cargo was also altered in the EVs from bioreactor culture including the upregulation of miR-10, 19a, 19b, 21, 132, and 377. EV protein cargo was characterized by proteomics analysis, showing upregulation of metabolic, autophagy and ROS-related proteins comparing with 2D cultured EVs. In addition, the scalability of the Vertical-Wheel bioreactor system was demonstrated in a 0.5L bioreactor, showing similar or better hMSC-EV secretion and cargo content compared to the 0.1L bioreactor. This study advances our understanding of bio-manufacturing of stem cell-derived EVs for applications in cell-free therapy towards treating neurological disorders such as ischemic stroke, Alzheimer's disease, and multiple sclerosis.

During vascular development, endothelial cells (ECs) undergo arterialization in response to genetic programs and shear stress-triggered mechanotransduction, forming a stable vasculature. Although the Notch receptor is known to sense shear stress and promote EC arterialization, its downstream mechanisms remain unclear. In this study, the Notch downstream miR-342-5p was found to respond to shear stress and promote EC arterialization. Shear stress upregulated miR-342-5p in a Notch-dependent manner in human umbilical vein endothelial cells (HUVECs). miR-342-5p overexpression upregulated the shear stress-associated transcriptomic signature. Moreover, miR-342-5p upregulated arterial markers and promoted EC arterialization in a Matrigel plug assay and retinal angiogenesis model. In contrast, miR-342-5p knockdown downregulated arterial markers, compromised retinal arterialization, and partially abrogated shear stress and Notch activation-induced arterial marker upregulation. Mechanistically, miR-342-5p overexpression suppressed MYC to repress EC proliferation and promote arterialization, achieved by promoting MYC protein degradation by targeting the EYA3. Consistently, EYA3 overexpression rescued miR-342-5p-mediated MYC downregulation and EC arterialization. In vivo, miR-342-5p expression was notably decreased in the ligated artery in a hindlimb ischemia model, and an intramuscular injection of miR-342-5p promoted EC arterialization and improved perfusion. In summary, miR-342-5p, a mechano-miR, mediates the effects of shear stress-activated Notch on EC arterialization and is a potential therapeutic target for ischemic diseases.

The formation of bed form in alluvial rivers due to sediment transport has a significant effect on the hydraulic parameters of the flow such as bed shear stress. The formation of the bed form and its shape and geometry depends on the bed shear stress. Therefore, the relationship between bed form and flow parameters (such as bed shear stress) is complicated. In the present study; the effect of dune bed forms with different heights on bed shear stress has been investigated. Artificial dunes made by sand-cement mortar with a length of 25 cm and heights of 1, 2, 3, and 4 cm were used. In the tests of this research, flow discharge of 10, 15, 20, 25, and 30 l/s and bed slopes of 0, 0.0001, 0.0005, 0.001, and 0.0015 were used. The results showed that with increasing the relative submergence and Δ/λ, the bed shear stress increased in dune-covered beds. The formation of the dune bed form and the increase in its height leads to an increase in the bed shear stress. The bed shear stress in dunes with a height of 1, 2, 3, and 4 cm was, on average, 39, 80, 141, and 146% more than in plane beds, respectively. Moreover, form shear stress for dunes with a height of 1, 2, 3, and 4 cm was, on average, 27.37, 43, 57.11, and 58.74% of the total shear stress, respectively.

This study aims to investigate the process and mechanism of adsorption of Zn(II) and Pb(II) by river sediments under hydrodynamic conditions. Surface sediments were collected from the Ganjiang River in Nanchang, China, and the adsorption characteristics of heavy metals Zn(II) and Pb(II) under different hydrodynamic conditions were simulated using the particle entrainment simulator. The results showed that under different hydrodynamic conditions, the adsorption equilibrium of Zn(II) and Pb(II) can be reached within 6h, and the adsorption amount of Pb(II) by the sediment was significantly higher than that of Zn(II). Pseudo-second-order dynamics and the Elovich model can better describe the kinetics of adsorption in both metals (R2 > 0.90). The Langmuir model and Freundlich model could better simulate the adsorption isotherms of Zn(II) and Pb(II) on sediments, which revealed that the adsorption spots are heterogeneous. According to the △G and −F results the adsorption of Zn(II) and Pb(II) is mainly physical adsorption. Furthermore, there are certain differences in the adsorption of heavy metals Zn(II) and Pb(II) by sediments at different pH, where the adsorption amount of Zn(II) increases with the increase of pH, but Pb(II) is not sensitive to the change of pH. HIGHLIGHTS Pseudo-second-order kinetics and Elovich models could better describe the kinetic process of adsorption of both metals.; Langmuir and Freundlich models could better simulate the adsorption isotherms of Zn(II) and Pb(II) on sediments.; The adsorption rate of Zn(II) and Pb(II) on sediments increased with increasing shear stress.;

Membrane bioreactors (MBRs) are high-tech systems for water recycling and reusing of unconventional water resources such as municipal wastewater. However, the fouling of polymeric membranes is the main impediment to the market development of MBR. The polyolefin-based membranes are subjected to more severe organic fouling than other hydrophilic membranes due to their inherent strong hydrophobic properties, therefore, proposing efficient, fast, and economic fouling mitigation methods is vital for durable and long-standing performance. In this research, the hydrodynamics of a lab-scale membrane bioreactor with different configurations of aerators and nozzle sizes were used to investigate the air scouring efficiency. It was gained that aerators with higher air flow rates, e.g., 5.5 m/s can produce slug bubbles which are capable of foulant removal from the membrane surface. In comparison with a non-central aerator, the satisfactory scouring zone of the central aerator is narrow and the edge nozzles on both sides of the aerator are blocked. Under constant air flow rate, when the inlet air is injected into the aerator from two and three points, not only the end nozzles are blocked but also the liquid is penetrated into the aerator and the shear stress on the membrane surface decreased to 0.765 Pa. In the case of the non-central aerator, the satisfactory scouring zone becomes wider and neither nozzle blockage nor liquid penetration down to the aerator has occurred. The distribution of bubbles was optically evaluated by video imaging through the transparent plexiglass tank using aerators with different inlet flow rates and various configurations. Numerical simulations and related experimental analyses demonstrated that air inlet velocity has an important role in creating larger slug bubbles. It was shown that a non-central aerator in which the central nozzle in front of the inlet air stream is blocked, produces slug bubbles and sufficient air scoring on the flat sheet membrane. Configuration of a non-central aerator with 4 nozzles not only increased the satisfactory zone of each aerator without blockage of edge nozzles and liquid penetration into the aerator but also provided a higher shear rate over 1.104 Pa under a constant flow rate, which consequently removed the foulant from the membrane surface.

Abstract High fracture density in fault damage zones not only reduces the elastic stiffness of rocks but may also promote time‐dependent bulk deformation through the sliding of fracture and thus alter the stress in fault zones. On comparing the damage zones of the three faults in the Chelungpu fault system encountered in the Taiwan Chelungpu fault Drilling Project (TCDP), the youngest damage zone showed pronounced sonic velocity reduction even though fracture density is the same for all three fault zones, consistent with the shorter time for velocity recovery in the youngest fault. Caliper log data showed a time‐dependent enlargement of the borehole wall at the damage zone. These damage zones record lower differential stress than the surrounding host rock, which cannot be explained by the reduced elastic stiffness in the damage zone. Stress relaxation caused by time‐dependent bulk deformation in the damage zone may be responsible for the observed low differential stress.

Orbitally shaken bioreactors are extensively applied to the mass production of mammalian cells in suspension culture. Commonly used vessels are cylindrical tanks and their main disadvantage is the accumulation of cells at the bottom center. To eliminate this accumulation issue, an annular cylindrical vessel is proposed for orbitally shaken bioreactors using numerical simulation. This approach eliminates the center of the vessel physically and thus removes the possibility of such cell accumulation. The absence of a central section in the vessel significantly improves the dissolved oxygen concentration and cell suspension ratio in the culture medium without increasing the shear stress. It also efficiently removes the possibility of cell aggregation at the bottom. An advanced machine learning technology - Bayesian optimization algorithm is also employed in the hollow orbitally shaken bioreactor to optimize the three main control parameters of the reactor, namely, diameter ratio (di/do), shaking velocity (ω), and shaking radius (R). The obtained data related to mass transfer ability, suspension ratio, and shear stress are analyzed. The numerical simulation results show that the “optimal” bioreactor is preferable for cell cultivation compared with the “initial state”, owing to its high capability for suspending cells. It can be concluded that the methodology described in this work is a feasible and reliable tool for performance prediction and process optimization in biotechnology.

AbstractBecause a variety of fuels can be burned during the combustion process, CFB boilers have a very wide range of applications in coal-fired power plants. The uneven distribution of homogeneity between the air and the particles and the large volume fraction in some locations could result in erosion of the furnace walls. In order to decrease the impacts of erosion, the ring baffle feature is added to the furnace wall. In order to compare data variations in the form of ring baffle depth with variations of 0.15 m, 0.3 m, and 0.45 m as well as the number of ring baffles 1 and 2, the CFD approach is utilized. The factors tested included pressure drop distribution, particle volume fraction distribution, particle axial and radial velocity distribution, and shear stress. With a maximum value of 0.012 for the volume percent, the variation of two ring baffles with a depth of 0.3 m each offered the best results in terms of homogeneity inside the CFB of the boiler. Additionally, a pressure decrease of 7.38 kPa was seen due to the maximum axial and radial speeds that were measured at the ring baffle, which were 27.1 m/s and 2.46 m/s, respectively. Additionally, the furnace wall can avoid probable erosion thanks to the shear stress contours, which mirror the volume percentage of particles.

The Schlemm’s canal (SC) is a circular, lymphatic-like vessel located at the limbus of the eye that participates in the regulation of aqueous humor drainage to control intraocular pressure (IOP). Circumferential flow of aqueous humor within the SC lumen generates shear stress, which regulates SC cell behaviour. Using biochemical analysis and real-time live cell imaging techniques, we have investigated the activation of autophagy in SC cells by shear stress. We report, for the first time, the primary cilium (PC)-dependent activation of autophagy in SC cells in response to shear stress. Moreover, we identified PC-dependent shear stress-induced autophagy to be positively regulated by phosphorylation of SMAD2 in its linker and C-terminal regions. Additionally, SMAD2/3 signaling was found to transcriptionally activate LC3B, ATG5 and ATG7 in SC cells. Intriguingly, concomitant to SMAD2-dependent activation of autophagy, we also report here the activation of mTOR pathway, a classical autophagy inhibitor, in SC cells by shear stress. mTOR activation was found to also be dependent on the PC. Moreover, pharmacological inhibition of class I PI3K increased phosphorylation of SMAD2 at the linker and activated autophagy. Together, our data indicates an interplay between PI3K and SMAD2/3 signaling pathways in the regulation of PC-dependent shear stress-induced autophagy in SC cells.