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The paper and dataset on the modelling of foam deglutition in a replica of a human mouth cavity. It includes the optical measurement of elastic stresses and bubble flows of the foam flow furing the deglutition. Each data folder includes: Laborbuch.xls labbook Fluessigkeitsgehalt--data on liquid fraction 1. masking2.mlx script --- script to create the mask for the tongue and palete plates 2.025 --- original data folder 3.025_pre --- cutted (to ROI) image data folder 4.025_pre_predict --- folder with the ANN processed data, with enhanced bubble positions 5.masked2--- masked images 6.SCRIPTS--- folder with the matlab scripts 6.* some video for the visualisation 7. Calculate_new-- folder with the scripts used for the calculation. Including: common_mod.msx --- common matlab file for the stress data at the right wall left_common_mod.msx --- common matlab file for the stress data at the left wall tau_loc_left.m -- to plot the graph all_script.msx --- run the common file for all the images bub_parts -- folder with the files to define bubble velocity: full_bub-- velocity of full bubble

In den letzten Jahren gab es Fortschritte im Verständnis der Gefäßbildung bei Ereignissen wie Keimen, Lumenbildung und Gefäßstabilisierung. Nach der Bildung eines primitiven Plexus ist die Gefäßoptimierung und hierarchische Umwandlung der morphologischen Gefäße in einen reifen Plexus durch vaskuläres "Pruning" wenig verstanden. Unterschiedliche Blutflussprofile in nebeneinander angeordneten Gefäßen können Asymmetrien in der Scherspannung verursachen, was die Zellmigration in Bereichen mit höherem Fluss fördert und die Destabilisierung von Segmenten mit geringem Fluss induziert. Diese Studie basiert auf der Hypothese, dass funktionelle Gefäßnetzwerke und Umbildung durch flussgesteuerte Endothelzellmigration ausgelöst werden. Wie die zelluläre Erfassung physikalischer Kräfte integriert ist, um Informationen zu übertragen und das Verhalten von Zellen zu modifizieren, ist noch unbekannt. Die Studie untersucht die Regulation und Koordination durch RhoGTPase-Signale während der kollektiven endothelialen Migration aufgrund von Flüssigkeitskräften. RhoGTPasen ermöglichen die räumlich-zeitliche Koordination, langfristige Anpassung an den Fluss und morphologische Umgestaltung. Beeinträchtigungen von RhoGTPasen zeigen Defekte bei Zellmigration und kollektiver Koordination in Umgebungen mit freiem Rand und strömungsgetriebener Migration. Die Studie erläutert den Einfluss der RhoGTPase-Regulation der Verbindungsdynamik in Verbindung mit der Aktinorganisation, die für die mechanische Kopplung und endotheliale Reaktionsfähigkeit erforderlich ist. Insgesamt betont die Studie die Relevanz der räumlich-zeitlichen RhoGTPase-Kontrolle und der Aufrechterhaltung der mechanischen Kopplung zwischen Strömung und Migration für die kollektive Koordination als Reaktion auf hämodynamische Kräfte., In recent years, there have been significant advances in understanding how new vessels form during events like sprouting, lumen formation, and vessel stabilization. Yet, after the formation of a basic network, the crucial step of rearranging vessels into a mature structure, known as vascular pruning, needs further investigation. It's suggested that different blood flow profiles in nearby vessels create imbalances in shear stress, leading to cell migration toward higher flow regions, destabilizing low-flow segments, and causing the collapse of redundant segments. This study, in line with existing literature, proposes that functional vascular networks and remodeling result from the flow-driven migration of endothelial cells. However, how cells precisely sense physical forces to regulate their behavior and coordinate migration in response to flow remains unknown. I explore the regulation and coordination of Rho GTPases during collective endothelial migration under fluid forces. Rho GTPases' coordination allows long-term adaptation to flow and morphological remodeling. Impairments in Rho GTPases reveal defects in cell migration and collective coordination during free-edge and flow-driven migration. Finally, I explain how Rho GTPases' regulation influences junctional dynamics and actin organization, crucial for mechanical coupling and endothelial responsiveness to flow. Overall, this study emphasizes the importance of controlling Rho GTPases over time and maintaining mechanical coupling between flow and migration for collective coordination in response to fluid forces.

BACKGROUND: Severe 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. METHODS: The 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. RESULTS: The 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. DISCUSSION: Our 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.

This data delves into the hydrodynamic intricacies within an open channel featuring continuous double-layered vegetation along both banks. Measurements are undertaken using nonintrusive laser diagnostics (LDV) to assess velocity, shear stress, and turbulence intensity. Two double-layered vegetation configurations, uniform growth (A1) and mixed growth (A2), were examined in conjunction with four aspect ratios (AR-6.67, 5.00, 4.00, and 2.63). The raw data were acquired using "BSA Flow Software v5.00", provided by DANTEC DYNAMICS, Denmark, and the extracted data used for the analysis was included in the Excel sheets for the purpose of sharing.

Das Ziel dieser Arbeit war die Etablierung eines Kultivierungskonzepts zur Endothelialisierung einer bioartifiziellen Gefäßprothese. Dazu wurde zunächst eine passende patienteneigene (autologe) Endothelzellquelle gesucht, die den klinischen Anforderungen einer endothelialisierten Gefäßprothese entsprachen. Dazu zählt, dass die verwendeten Endothelzellen einer leicht zugänglichen Quelle entstammen und immunologisch neutral eingesetzt werden können. Im Rahmen dieser Arbeit wurde gezeigt, dass endotheliale koloniebildende Zellen (ECFCs) aus dem peripheren Blut in hoher Anzahl in unbeschichteten Zellkulturgefäßen ohne den Zusatz von artifiziellen Matrixproteinen isoliert und vermehrt werden konnten. Durch die Vermeidung fremdartiger (allogener) Oberflächenbeschichtungen wurden Richtlinien für Arzneimittel neuartiger Therapien (ATMP) berücksichtigt, die für die zukünftige medizinische Zulassung der bioartifiziellen Gefäßprothese relevant sind. Neben der immunologischen Neutralität der Zellen sollten die angesiedelten Endothelzellen auch ihre funktionellen und adhäsiven Eigenschaften unter in vivo Strömungsbedingungen beibehalten. Daher wurde die Auswirkung verschiedener Scherstressprofile sowie der Einfluss eines physiologischen Pulses auf die Funktion sowie Mechanosensitivität der isolierten ECFCs im Vergleich zu klassischen endothelialen Modellzellen aus der Literatur, den humanen Nabelschnurvenenendothelzellen (HUVECs), untersucht. Ein pulsatiler arterieller Scherstress erwies sich dabei als erforderlich, um in ECFCs eine signifikante Veränderung der Zellmorphologie, Zellausrichtung und Zell-Zell-Verbindungen hervorzurufen. Zudem wurde analysiert, inwieweit eine Vorkonditionierung unter einem hohen Scherstress zur arteriellen Differenzierung der unreifen ECFCs führte. In diesem Zusammenhang wurde gezeigt, dass eine dynamische Kultivierung der ECFCs unter einem arteriellen Scherstress ein Genprofil induzierte, das mehr in Richtung eines arteriellen als eines venösen Ph

A cohesive interface model based on a master curve is proposed for the analysis of delamination in paperboard under various loading, unloading, and reloading conditions. The model is thermodynamically consistent and considers the effects of elasticity, plasticity, and damage. The proposed model is verified by comparing its predictions with experimental data obtained from multiple loading–unloading–reloading cycle experiments using a split double cantilever beam specimen. The results show that the model can predict the cyclic behavior of shear loading and provide insight into the damage evolution associated with different loading paths by analyzing the shear stress distribution in the fracture process zone. The model’s calibration process requires monotonic normal and shear loading data but only cyclic normal loading data. Additionally, the model accounts for the paperboard’s fiber–fiber friction and normal dilatation due to shear loading. In total, nine parameters are needed to calibrate the mode.

Objective: Three dimensional cell and tissue culture outcomes depend on mechanical forcesin their environment and sufficient delivery of nutrients and removal of waste. Flow and shear influence parenchymal cell distribution and vascular morphogenesis. Herein a bioreactor which can control fluid flow and shear patterns over large areas was developed as a tool for tissue engineering. Methods: A 12-inlet perfusion bioreactor was constructed to be compatible with multiple types of tissue engineering scaffolds including biopolymer hydrogels and macroporous sponges and can support the growth and viability of thick tissue scaffolds. Scaffolds containing mammalian cells cultured under flow were compared to static conditions and other flow patterns. Results: Flow patterns in the scaffolds were obtained using MRI flow maps. Hydrogels and commercial sponges were assessed for 3D culture compatibility and Gel 2 (a specific ECM hydrogel mixture), Collagen, and Gelatin sponges were found to be both optimal for cell growth and compatible with perfusion flow. Culture experiments determined the feasibility of our bioreactor in supporting thick tissue growth and viability and various flow patterns were shown to alter cell distribution, growth, and viability. Conclusion: We demonstrated the ability of the bioreactor to implement macroscopic, tunable flow patterns in a biocompatible environment suitable for cell and tissue culture and found distinct differences in tissue development from different flow patterns. Significance: The bioreactor will enable future studies on different flow patterns and their effects on cell growth and viability for medically relevant tissues and could inform on culture conditions that better mimic what occurs in vivo during tissue development.

The breakup of inertial, solid aggregates in an incompressible, homogeneous and isotropic three-dimensional turbulent flow is studied by means of a direct numerical simulation, and by a Lagrangian tracking of the aggregates at varying Stokes number and fluid-to-particle density ratio. Within the point-particle approximation of the Maxey–Riley–Gatignol equations of motion, we analyze the statistics of the time series of shear and drag stresses, which are here both deemed as responsible for aggregate breakup. We observe that, regardless of the Stokes number, the shear stresses produced by the turbulent velocity gradients similarly impact the breakup statistics of inertial and neutrally buoyant aggregates, and dictate the breakup rate of loose aggregates. When the density ratio is different from unity, drag stresses become dominant and are seen to be able to cause to breakup of also the most resistant aggregates. A transition from a shear-dominated to a drag-dominated breakup regime is observed, and a power-law is seen to well describe the breakup rate of loose aggregates regardless of their inertia. The present work assesses the role of shear and drag stresses on aggregate breakup and computes breakup rates to be possibly used in population balance models., QC 20230710

This work developed a method for the investigation of how medical devices, such as syringes and needles, affect the formation of subvisible particles in a protein drug without excipients. Protein-based pharmaceuticals are well known to be sensitive to different kinds of stress, and exposure to stress during the use of this device is unavoidable. To study this phenomenon, an in-house built probe for the operation of syringes with a texture analyser was created. Mechanical stress was modulated by varying the expulsion speed, and related forces were captured by the texture analyser. The formation of particles was evaluated by dynamic light scattering(DLS), size exclusion chromatography(SEC) and flow imaging microscopy by FlowCAM. The insulin was found to be primarily present in its hexamer form, with a hydrodynamic diameter of 5.6 nm. FlowCAM showed increased concentration of particles in both siliconized and non-siliconized syringes after mechanical stress. The increase was associated with protein aggregates in the non-siliconized syringe, while increase in the the siliconized was mainly associated to silicone oil droplet formation. The particles were categorized by sphericity using circle fit and aspect ratio, with spherical cutoff at 0.85. The siliconized syringe had no increase in protein aggregates after stress and displayed a substantial loss of native protein (2.5 %) according to SEC. This concedes with findings from other studies and might be due to oil interface adsorption. Although, the size distribution from FlowCAM yielded particle counts, which were theoretically too low to account for this loss alone., Läkemedel som består av skräddarsydda proteiner används idag för att behandla bland annat diabetes. De ges traditionellt som injektioner och detta misstänks vara kopplat till skapandet av skadliga partiklar. Sprutan och nålen är ofta silikoniserade för att underlätta hantering och deras användning utsätter det känsliga proteinet för mekaniska krafter. Detta tros leda till bildandet av partiklar i form av silikon droppar och protein klumpar (aggregat). Detta arbete utvecklade därför en metod för att undersöka effekten av sprutor med nål på ostabiliserat insulin. En 3D printad spruthållare till en maskin som kan trycka och dra samtidigt som den mäter kraften (texturometer) designades för att kunna manövrera sprutan. Effekten av mekanisk påverkan undersöktes genom att variera tömningshastighastighen av sprutan. Endast hastigheter som var associerade med laminärt flöde underöktes. Osilikoniserade sprutor jämfördes mot silikoniserade. Tre vanligt förekommande analysmetoder (dynamisk ljusspridning, storlekskromatografi (SEC) och FlowCam) användes för att mäta partikelkoncentration och storlek. Spruthållaren i vit nylonplast presterade bra, tog tre dagar att skapa och kostade en tiondel av färdiga alternativ på marknaden. FlowCam mätningarna visade att partikelkoncentrationerna höll sig under tillåtna nivåer och steg med ökad tömningshastighet. FlowCam tog bilder av de individuella partiklarna i proven. Dessa kunde sedan användas för att se vilka slags partiklar proven innehöll. Silikondropparna var helt sfäriska med slät kant och hade ibland en reflektiv mitt. Det visade sig att koncentrationsökningen i den silikoniserade sprutan berodde på ökat antal silikonoljedroppar. I den osilikoniserade sprutan berodde ökningen istället på ett ökat antal partiklar som var ojämna, mörkare och med skrovlig kant. Dessa antogs vara proteinaggregat. Metoden som utvecklades kan i framtiden användas för att undersöka andra proteiner eller effekten av andra faktorer såsom övergångsflöde, up

An abdominal aortic aneurysm (AAA) is a critical health condition with a risk of rupture, where the diameter of the aorta enlarges more than 50% of its normal diameter. The incidence rate of AAA has increased worldwide. Currently, about three out of every 100,000 people have aortic diseases. The diameter and geometry of AAAs influence the hemodynamic forces exerted on the arterial wall. Therefore, a reliable assessment of hemodynamics is crucial for predicting the rupture risk. Wall shear stress (WSS) is an important metric to define the level of the frictional force on the AAA wall. Excessive levels of WSS deteriorate the remodeling mechanism of the arteries and lead to abnormal conditions. At this point, WSS-related hemodynamic parameters, such as time-averaged WSS (TAWSS), oscillatory shear index (OSI), endothelial cell activation potential (ECAP), and relative residence time (RRT) provide important information to evaluate the shear environment on the AAA wall in detail. Calculation of these parameters is not straightforward and requires a physical understanding of what they represent. In addition, computational fluid dynamics (CFD) solvers do not readily calculate these parameters when hemodynamics is simulated. This review aims to explain the WSS-derived parameters focusing on how these represent different characteristics of disturbed hemodynamics. A representative case is presented for spatial and temporal formulation that would be useful for interested researchers for practical calculations. Finally, recent hemodynamics investigations relating WSS-related parameters with AAA rupture risk assessment are presented. This review will be useful to understand the physical representation of WSS-related parameters in cardiovascular flows and how they can be calculated practically for AAA investigations. © 2023, NPRP13S-0108–200024; IRCC 2020-002; Qatar National Research Fund, QNRF; Qatar National Library, QNL; Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK: 221M001, This study is funded by Qatar University International Research Collaboration Co-Funds (IRCC) Program ( IRCC 2020-002 ) to HCY, Qatar National Research Fund (QNRF), National Priority Research Program ( NPRP13S-0108–200024 ) to HCY and OM, and TÜBİTAK (Scientific and Technological Research Council of Turkey) 3501 – Career Development Program (Project number: 221M001 ) to HES. The publication of this article was funded by the Qatar National Library.

An abdominal aortic aneurysm (AAA) is a critical health condition with a risk of rupture, where the diameter of the aorta enlarges more than 50% of its normal diameter. The incidence rate of AAA has increased worldwide. Currently, about three out of every 100,000 people have aortic diseases. The diameter and geometry of AAAs influence the hemodynamic forces exerted on the arterial wall. Therefore, a reliable assessment of hemodynamics is crucial for predicting the rupture risk. Wall shear stress (WSS) is an important metric to define the level of the frictional force on the AAA wall. Excessive levels of WSS deteriorate the remodeling mechanism of the arteries and lead to abnormal conditions. At this point, WSS-related hemodynamic parameters, such as time-averaged WSS (TAWSS), oscillatory shear index (OSI), endothelial cell activation potential (ECAP), and relative residence time (RRT) provide important information to evaluate the shear environment on the AAA wall in detail. Calculation of these parameters is not straightforward and requires a physical understanding of what they represent. In addition, computational fluid dynamics (CFD) solvers do not readily calculate these parameters when hemodynamics is simulated. This review aims to explain the WSS-derived parameters focusing on how these represent different characteristics of disturbed hemodynamics. A representative case is presented for spatial and temporal formulation that would be useful for interested researchers for practical calculations. Finally, recent hemodynamics investigations relating WSS-related parameters with AAA rupture risk assessment are presented. This review will be useful to understand the physical representation of WSS-related parameters in cardiovascular flows and how they can be calculated practically for AAA investigations. © 2023, NPRP13S-0108–200024; IRCC 2020-002; Qatar National Research Fund, QNRF; Qatar National Library, QNL; Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK: 221M001, This study is funded by Qatar University International Research Collaboration Co-Funds (IRCC) Program ( IRCC 2020-002 ) to HCY, Qatar National Research Fund (QNRF), National Priority Research Program ( NPRP13S-0108–200024 ) to HCY and OM, and TÜBİTAK (Scientific and Technological Research Council of Turkey) 3501 – Career Development Program (Project number: 221M001 ) to HES. The publication of this article was funded by the Qatar National Library.

Microfluidic devices have been studied and developed over the last decades due to their multiple biology applications. One of their fields of most interest is the organ-on-a-chip technology, which consists in emulating an organ on a microchip. This technology presents several advantages, from ethical aspects for stop experimenting with animals to the control of many parameters while performing an experiment. This master?s thesis explores new microfluidic devices designs in order to study the malaria?s parasite \textit{Plasmodium vivax}, which is one of the main parasites that spread the disease. The parasite enters into the human body through the circulatory system, so the designs are focused on emulate blood vessels and the aim of this project is to search the best ways to ease the formation of a monolayer of endothelial cells over the walls of the channels of the microdevice under flow conditions. In concrete, the project studies the relation between the microdevices material PDMS and fluids as well as the interaction with microdevices walls when fluid is flowing through it in order to better the signs and achieve suitable parameters.

Background: Ischemic stroke is a major cause of death worldwide. Atherosclerosis in the carotid arteries is an established predictor of these events. FSI shows its advantage in simulating the hemodynamic environments due to involving the multiphysics coupling of fluid dynamics and structural mechanics regulations. Therefore, the aim of this thesis was to establish and demonstrate a framework, starting with the segment data extracted from CTA images and leading to patient-specific FSI modeling. Thus the results can be used to gain insights into the relationship between plaque changes over time and biomechanical stresses induced by blood flow using FSI. Method: 3D coordinates are firstly extracted from CTA scans of patients with calcified atherosclerotic plaques in their carotid arteries, sourced from the PARISK study. This data was then used to reconstruct 3D surfaces and volumes of the carotid bifurcation structure. Subsequently, the Backward Incremental method is employed to compute the initial stresses and establish the zero-pressure geometry of the vessel. Following this, FSI simulations were conducted on six carotid bifurcations to obtain preliminary results, providing an initial test of the pipeline's robustness. Morphological changes, including plaque burden, wall thickness, and calcium distance, are quantified to study plaque progression over time. The numerical simulation results provide insights into biomechanical stresses, including fluid and solid wall shear stress and von Mises stress. The simulation results are subjected to post-processing for further analysis. The results are mapped to a 2D configuration, with 1.5mm along the centerline and 45 degree per sector to study the local behavior. Result: The efficacy of the reconstruction and initial stress detection methods shows the robustness of the pipeline. The entire process is executed on six vessels, with a comprehensive examination of one case presented initially. This, Mechanical Engineering

Shear stress is essential for normal physiology and malignancy. Common physiological processes - such as blood flow, particle flow in the gut, or contact between migratory cell clusters and their substrate - produce shear stress that can have an impact on the behavior of different tissues. In addition, shear stress has roles in processes of biomedical interest, such as wound healing, cancer and fibrosis induced by soft implants. Thus, understanding how cells react and adapt to shear stress is important. In this Review, we discuss in vivo and in vitro data obtained from vascular and epithelial models; highlight the insights these have afforded regarding the general mechanisms through which cells sense, transduce and respond to shear stress at the cellular levels; and outline how the changes cells experience in response to shear stress impact tissue organization. Finally, we discuss the role of shear stress in collective cell migration, which is only starting to be appreciated. We review our current understanding of the effects of shear stress in the context of embryo development, cancer and fibrosis, and invite the scientific community to further investigate the role of shear stress in these scenarios.

While the three-dimensional (3D) shape and stress field of a twin in hexagonal close-packed (HCP) metals have attracted considerable interest in recent years due to their substantial impact on internal stress and mechanical properties, a detailed understanding of their variation with twin size is still lacking. An analytical model that is not restricted by spatial scale is developed in this work by considering the effects of anisotropic twin boundary energy, elastic strain energy and plastic relaxation to predict the 3D shape with the minimum energy, and the stress field, of an isolated ellipsoidal twin of different sizes. The model is applied to Mg with a focus on the {101¯2} twin type. The analytical calculation results show that the nucleation of the nano-sized twin embryos is facilitated by the stress field near structural defects such as dislocations. During the expansion of this nano-sized twin embryo, the interplay between the elastic strain energy and interfacial energy changes the length of the twin along the twin shear (forward) direction from being shorter to longer than that along the lateral direction. In contrast to the current understandings, the maximum shear stress on the twin plane along the twin shear direction occurs at the lateral, rather than the forward, side of the twin. At the forward side, the maximum shear stress occurs at a distance ahead of the twin tip and this distance increases with increasing twin thickness.

Vizcardo-Galindo, Gustavo A., Connor A. Howe, Ryan L. Hoiland, Howard H. Carter, Christopher K. Willie, Philip N. Ainslie, and Joshua C. Tremblay. Impact of oxygen supplementation on brachial artery hemodynamics and vascular function during ascent to 5,050 m. High Alt Med Biol. 24:27-36, 2023. - High-altitude trekking alters upper limb hemodynamics and reduces brachial artery vascular function in lowlanders. Whether these changes are reversible with the removal of hypoxia is unknown. We investigated the impact of 20 minutes of oxygen supplementation (O2) on brachial artery hemodynamics, reactive hyperemia (RH; microvascular function), and flow-mediated dilation (FMD; endothelial function). Participants (aged 21-42 years) were examined before and with O2 at 3,440 m (n = 7), 4,371 m (n = 7), and 5,050 m (n = 12) using Duplex ultrasound (days 4, 7, and 10 respectively). At 3,440 m, O2 decreased brachial artery diameter (-5% ± 5%; p = 0.04), baseline blood flow (-44% ± 15%; p < 0.001), oxygen delivery (-39 ± 16; p < 0.001), and peak RH (-8% ± 8%; p = 0.02), but not RH normalized for baseline blood flow. Elevated FMD (p = 0.04) with O2 at 3,440 m was attributed to the reduction in baseline diameter. At 5,050 m, a reduction in brachial artery blood flow (-17% ± 22%; p = 0.03), but not oxygen delivery, diameter, RH, or FMD occurred with O2. These findings suggest that during early trekking at high altitude, O2 causes vasoconstriction in the upper limb along the arterial tree (conduit and resistance arteries). With incremental high-altitude exposure, O2 reduces blood flow without compromising oxygen delivery, RH, or FMD, suggesting a differential impact on vascular function modulated by the duration and severity of high-altitude exposure.

Timber-concrete composite (TCC) structures are becoming more popular in several industrial applications as an efficient method for optimizing the structural performance and the cost of construction as well as lowering the emissions of carbon dioxide. TCC floors are more sustainable than pure concrete floors and more resistant to vibrations and excessive deflections than pure wooden floors. The effectiveness of a TCC floor is dependent on the connection between the materials. The stiffness and strength of the composite element increases by having a rigid connection. An example of a rigid connection is an adhesive-bonded connection, however obtaining a connection without slip is difficult considering there will always be certain amount of slippage in the connection. In this thesis adhesive connections are investigated with two different types of adhesive, one called Sikasil SG-500 and the other Sika PS. The application of the adhesives for the test specimen differ. Since Sika PS is a more fluid glue, a different approach was necessary than for the Sikasil SG-500. Five test specimen were tested of each adhesive by performing double shear push out tests and comparing the results to a numerical model, which was performed in ABAQUS. In the numerical model, the adhesive was created as a cohesive element. Furthermore the properties of the modeled adhesive was based on the experimental results for respective adhesive. The experimental results showed that both adhesives managed the estimated shear force in the serviceability limit state and the ultimate limit state and yet remained in the elastic region. Sikasil SG-500 turned out to be more flexible while Sika PS specimen resulted in higher shear strength. The short creep tests (30 minutes of a constant load) showed that the deformation increased more for Sika PS than for Sikasil SG-500. However both adhesives had large deformations after only 30 minutes. There was also a difference in the average longitudinal shear strength

Proper meshing is critical for accurate computational fluid dynamics (CFD) simulation. In the three stages of CFD simulation, pre-processing accounts for about 40–60% of the total time. In this study, the performance of the grid for a large number of numerical simulations was analyzed, and base mesh sizes were recommended for different indoor geometric models. The simulation results for temperature, velocity, mesh resolution and computation time were compared, and mesh types were recommended for different models. Considering factors such as wall function, wall y+, face quality of the mesh, grid volume change rate and prism layer setting, a semi-empirical mesh strategy was presented. This strategy was verified in three cases with different geometric complexity. The verification results showed that the mesh strategy can yield reasonable simulation results. The root-mean-square error of the velocity simulation results of the optimized grid can be reduced by nearly 20%. This strategy can save nearly 50% of the mesh adjustment time. Through analysis and fitting of the grid results, the evaluation criteria for this mesh strategy were obtained. The criteria can be used to evaluate the cases using this mesh strategy., QC 20230227

This work reports an experimental and theoretical analysis of the rheological properties of mineral oil-based SiO2 nanofluid for their potential applications in transformer insulation. The flow electrification mechanism on the nanofluids with different surfactants such as cetyl trimethyl ammonium bromide (CTAB), oleic acid, and Span 80 is studied using a spinning disk technique. The results show a higher streaming current for the nanofluids with CTAB as a surfactant compared to oleic acid and Span 80. The rheological behavior of nanofluids is explored with the double gap concentric cylinder geometry. The variation of shear stress with shear rate follows a power law relationship along with a yield stress observed for all the nanofluids. A transition is seen from storage modulus to dominant loss modulus for the nanofluids during the frequency sweep analysis, whereas no transition is observed in the case of mineral oil. In addition, regression analysis using artificial neural network (ANN) algorithms are performed on the experimentally measured viscosity of the nanofluids in order to estimate theoretical parameters and provide insights into the streaming current formation. The desirable rheological characteristics of nanofluids are identified for achieving enhanced insulation performance in transformers., QC 20220718

Cardiothoracic surgeons are faced with a choice of different revascularization techniques and diameters for saphenous vein grafts (SVG) in coronary artery bypass graft surgery . Using computational simulations, we virtually investigate the effect of SVG geometry on hemodynamics of both venous grafts and the target coronary arteries. We generated patient-specific 3-dimensional anatomic models of coronary artery bypass graft surgery patients and quantified mechanical stimuli. We performed virtual surgery on 3 patient-specific models by modifying the geometry vein grafts to reflect single, Y, and sequential surgical configurations with SVG diameters ranging from 2 mm to 5 mm. Our study demonstrates that the coronary artery runoffs are relatively insensitive to the choice of SVG revascularization geometry. We observe a 10% increase in runoff when the SVG diameter is changed from 2 mm to 5 mm. The wall shear stress of SVG increases dramatically when the diameter drops, following an inverse power scaling with diameter. For a fixed diameter, the average wall shear stress on the vein graft varies in ascending order as single, Y, and sequential graft in the patient cohort. The runoff to the target coronary arteries changes marginally due to the choice of graft configuration or diameter. The shear stress on the vein graft depends on both flow rate and diameter and follows an inverse power scaling consistent with a Poiseuille flow assumption. Given the similarity in runoff with different surgical configurations, choices of SVG geometries can be informed by propensity for graft failure using shear stress evaluations.

In the present work the evolution of the boundary layer over a low-pressure turbine blade is studied by means of direct numerical simulations. The set-up of the simulations follows the experiments by [1], aiming to investigate the unsteady flow field induced by the rotor-stator interaction. The free-stream flow is characterized by high level of free-stream turbulence and periodically impinging wakes. As in the experiments, the wakes are shed by moving bars modeling the rotor blades and placed upstream of the turbine blades. To include the presence of the wake without employing an ad-hoc model, we simulate both the moving bars and the stationary blades in their respective frames of reference and the coupling of the two domains is done through appropriate boundary conditions. The presence of the wake mainly affects the development of the boundary layer on the suction side of the blade. In particular, the flow separation in the rear part of the blade is suppressed. Moreover, the presence of the wake introduces alternating regions in the streamwise direction of high- and low-velocity fluctuations inside the boundary layer. These fluctuations are responsible for significant variations of the shear stress. The analysis of the velocity fields allows the characterization of the streaky structures forced in the boundary layer by turbulence carried by upstream wakes. The breakdown events are observed once positive streamwise velocity fluctuations reach the end of the blade. Both the fluctuations induced by the migration of the wake in the blade passage and the presence of the streaks contribute to high values of the disturbance velocity inside the boundary layer with respect to a steady inflow case. The amplification of the boundary layer disturbances associated with different spanwise wavenumbers has been computed. It was found that the migration of the wake in the blade passage stands for the most part of the perturbations with zero spanwise wavenumber. The non-zero wavenum, QC 20230614

In the present work, high-fidelity direct numerical sim- ulation (DNS) data has been adopted in conjunction with an extensive post-processing to provide a detailed descrip- tion of the turbulence characteristics and its production within a low pressure turbine (LPT) cascade blade pas- sage operating with unsteady inflow. Proper orthogonal decomposition is used at first to provide the statistical rep- resentation of the flow structures that occur in the blade passage. Different inlet turbulent scales are isolated and a representation of the turbulence produced in the passage is also provided. Principal axes of the Reynolds stress and the strain tensors have been analyzed to provide further insight on the turbulence production. Since each spatial POD mode captures a quota of the Reynolds stress ten- sor, the POD modes are well suited to provide reduced order models (ROMs) that represent the different scales of turbulence. Namely, four different scales are defined, and the eigenvectors of the stress tensor for each reduced model are discussed. The discussion includes the compar- ison with the principal axis of the strain rate tensor. It is shown that the spatial locations where the eigen- vectors of the strain and stress tensors are aligned lead to the largest production of turbulent kinetic energy. The de- terministic periodic perturbations induced at the inlet by the unsteady incoming wakes lead to the largest produc- tion of turbulence in the passage region where the highest strain is detected and where the eigenvectors of the two tensors are aligned. In the suction side boundary layers, the highest production is related to the local maximum of the Reynolds shear stress due to the stochastic perturba- tions. The deterministic perturbations do not contribute to the production of turbulence in the suction side bound- ary layer, even though their induced stress is not negli- gible, because the eigenvector directions have a maximum misalignment., QC 20230614

Food texture is a very important factor for elderly persons, children, and patients who have difficulty swallowing. Collagen and its hydrolysis product, gelatin, are used as ingredients in foods, dietary supplements, and medical materials. In this study, we extracted atelocollagen from nonedible porcine tissues, including ear, nose, and skin, and analyzed the biophysical properties of each tissue. Extracted whole auricle collagen (AEC) showed superior springiness, while only the skin region of auricle collagen (ASC) showed superior hardness, springiness, and brittleness. Body skin collagen showed high hardness but low springiness. In a shear stress test, ASC gels showed high shear strength, and their strains coincided with hardness in a textural examination, while nose and AEC showed low maximum strains. In viscosity, the auricular collagens showed higher viscosity regardless of the region of the ear. Fibril formation in collagen from each tissue and organ varied a great deal in width and morphology. We found that the same type of collagen had a unique texture and viscosity under physiological conditions depending on the tissue or organ of extraction. The results show that the collagen extracted from each organ has a unique texture and unique possibilities to serve as an ingredient in food or supplements.

[Abstract]: When a pressurized liquid enters a pipeline with a closed-end and under vacuum conditions, the resulting liquid front suddenly is brought to rest at the end of the pipe. This type of flow configuration is found in propulsion systems of satellites during priming operation and induces a fluid hammer followed by a column separation, generating a multiphase gas/vapor bubble. This paper aims at explaining the column separation mechanism by solving the momentum equation for the liquid column moving in the pipeline when column separation occurs, and by applying the integral form of the conservation principles to expansion and compression waves within the flow. The resulting model provides the velocity and position of the liquid front during column separation. Thus, the size and duration of the multiphase bubble can be determined, and the variables involved in the process are identified, which helps on the analysis of applications where this complex phenomenon is involved. It is shown that the initial velocity of the liquid front during column separation is the main parameter, which itself is a function of the fuel tank pressure and the fluid hammer pressure rise. The comparison of the predictions with experimental data shows an excellent agreement.

Hypodermic needles are used in a wide range of medical procedures. In these procedures, an insertion force is applied to the needle to insert it through the soft tissue. In that way, when the tip of the needle encounters the surface of the tissue, several opposing forces are generated, such as stiffness, friction, and cutting forces, because of the tissue surface tension and viscoelastic properties. In addition, insertion force can influence tissue tearing and needle deflection. Thus, it is crucial to understand and analyze these forces and their effect on the tissue. We experimentally tested several commercial hypodermic needles at different diameters and bevel angles of the needle tips using an in-house test bench at different insertion velocities. In addition, chicken breasts were used as biological tissue to test the needles. As a result, the experimental cutting force increases linearly concerning the diameter of the needle and the insertion velocity. Also, the shear stress remains constant concerning insertion velocity and increases linearly with needle diameter and length. In conclusion, the results let us understand that the insertion mechanism is not trivial due to the influence of the geometry and relative velocity of the needle while penetrating the tissue and the mechanical properties of the soft tissue. All these combined parameters present challenging research to optimize medical procedures with needles., Peer Reviewed, Postprint (published version)

Wall shear stress (WSS) is involved in coronary artery plaque pathological mechanisms and modulation of gene expression. This study aims to provide a comprehensive haemodynamic and biological description of unstable (intact-fibrous-cap, IFC, and ruptured-fibrous-cap, RFC) and stable (chronic coronary syndrome, CCS) plaques and investigate any correlation between WSS and molecular pathways.

Flow turbulence modeling is an expensive computational operation that is often run with simulations using physical simplifications to reduce the cost. Large-eddy simulations (LES) of turbulent flow often make use of wall models in order to lower the computational cost of the simulation in the regions near solid walls, where typically the flow activity contains the smallest structures. Instead of resolving the boundary layer spatiotemporal scales, an algebraic expression for the fluid velocity field yields the wall shear stress, which is then used as a boundary condition to the outer flow, also known as wall modeling. Recently, novel wall model formulations are being developed using data-driven methods which exploit datasets generated with accurate wall-resolved large eddy simulation. However, it is still unclear what dimensional groups should be used to normalise such datasets when the wall shear stress is the target output, rather than a known quantity. The first goal of this dissertation is to explore such relevant groups across the dataset using machine learning applications as multi-expression genetic programming, a tool that allows to derive optimal expressions based on a population of initial candidates and a fitness function. The second goal is to be able to use it to find a correcting expression that yields the wall shear stress given other data and the defined groups.

The endothelium is a mechanosensitive organ whose pleiotropic actions regulate vessel structure to adjust tissue perfusion. To do so, it possesses ion channels, receptor complexes, and signaling pathways responding to blood flow, whose activation will either maintain vascular integrity and quiescence or, on the contrary, remodel the vessel's structure in both health and disease. Recent studies have demonstrated the crucial role of endothelial inflammation, endothelial to mesenchymal transition (EndMT), and perturbed hemodynamics in the progression of pulmonary arterial hypertension and essential hypertension. These two distinct diseases share some common mechanistic cues, pointing towards new potential therapeutic approaches to treat them. In this review, we summarize these common mechanisms to map future drug development strategies targeting flow sensing mechanisms and vascular remodeling., SCOPUS: re.j, info:eu-repo/semantics/published

The reliability of conventional cell culture studies to evaluate biomaterials is often questioned, as in vitro outcomes may contradict results obtained through in vivo assays. Microfluidics technology has the potential to reproduce complex physiological conditions by allowing for fine control of microscale features such as cell confinement and flow rate. Having a continuous flow during cell culture is especially advantageous for bioactive biomaterials such as calcium-deficient hydroxyapatite (HA), which may otherwise alter medium composition and jeopardize cell viability, potentially producing false negative results in vitro. In this work, HA was integrated into a microfluidics-based platform (HA-on-chip) and the effect of varied flow rates (2, 8 and 14 µl/min, corresponding to 0.002, 0.008 and 0.014 dyn/cm2, respectively) was evaluated. A HA sample placed in a well plate (HA-static) was included as a control. While substantial calcium depletion and phosphate release occurred in static conditions, the concentration of ions in HA-on-chip samples remained similar to those of fresh medium, particularly at higher flow rates. Pre-osteoblast-like cells (MC3T3-E1) exhibited a significantly higher degree of proliferation on HA-on-chip (8 μl/min flow rate) as compared to HA-static. However, cell differentiation, analysed by alkaline phosphatase (ALP) activity, showed low values in both conditions. This study indicates that cells respond differently when cultured on HA under flow compared to static conditions, which indicates the need for more physiologically relevant methods to increase the predictive value of in vitro studies used to evaluate biomaterials.

Treatment of unruptured intracranial aneurysms can reduce the risk of subarachnoid hemorrhage and its associated morbidity and mortality. However, current methods to predict the risk of rupture and optimize treatment strategies for intracranial aneurysms are limited. Assessment of intra-aneurysmal flow using 4-dimensional magnetic resonance imaging (4D MRI) is a novel tool that could be used to guide therapy. A systematic search of the literature was performed to provide a state-of-the-art review on 4D MRI assessment of unruptured intracranial aneurysms. A total of 18 studies were available for review. Eccentric flow on 4D MRI is associated with a greater aspect ratio and peak wall shear stress (WSS). WSS, vorticity, and peak velocity are greater in saccular than fusiform aneurysms. Unstable aneurysms are associated with greater WSS, peak wall stress, and flow jet angle and may exhibit wall enhancement. In comparison to computational fluid dynamics (CFD), 4D MRI has a lower spatial resolution and reports lower WSS and velocity magnitudes, but these parameters equalize when spatial resolution is matched. 4D MRI demonstrates the intra-aneurysmal hemodynamic changes associated with flow diversion, including significantly decreased flow velocity. Thus, 4D MRI is a novel, noninvasive imaging tool used for the evaluation of hemodynamics within intracranial aneurysms. Hemodynamic indices derived from 4D MRI appear to correlate well with the simulated (CFD) values and may be used to measure the success of endovascular therapies and risk factors for aneurysm growth and rupture.Copyright © 2020 by the Congress of Neurological Surgeons

Based on research carried out at 67 tailings dams in Spain: tailings dams contain alternating sedimentary layers with contractive and dilative geomechanical behaviours; tailings saturate quickly but drain more than 10 times slower due to the high-suction capacity of the porous sediments (2-300 MPa); and over the long-term, a stationary flow regime is attained within a tailings basin. Four temporal and spatial conditions must all be present for a tailing dams flow failure to occur: the tailings must experience contractive behaviour; the tailings must be fully saturated; the effective stress due to static or dynamic load must approach zero; and the shear stress must exceed the tailings residual shear stress. The results also indicate that the degree of saturation (Sr) is the most influential factor controlling dam stability. The pore-pressure coefficient controls geotechnical stability: when it exceeds 0.5 (Sr = 0.7), the safety factor decreases dramatically. Therefore, controlling the degree of tailings saturation is instrumental to preventing dam failures, and can be achieved using a double drainage system, one for the unconsolidated foundation materials and another for the overlying tailings. (Authors.), Based on research carried out at 67 tailings dams in Spain: tailings dams contain alternating sedimentary layers with contractive and dilative geomechanical behaviours; tailings saturate quickly but drain more than 10 times slower due to the high-suction capacity of the porous sediments (2-300 MPa); and over the long-term, a stationary flow regime is attained within a tailings basin. Four temporal and spatial conditions must all be present for a tailing dams flow failure to occur: the tailings must experience contractive behaviour; the tailings must be fully saturated; the effective stress due to static or dynamic load must approach zero; and the shear stress must exceed the tailings residual shear stress. The results also indicate that the degree of saturation (Sr) is the most influential factor controlling dam stability. The pore-pressure coefficient controls geotechnical stability: when it exceeds 0.5 (Sr = 0.7), the safety factor decreases dramatically. Therefore, controlling the degree of tailings saturation is instrumental to preventing dam failures, and can be achieved using a double drainage system, one for the unconsolidated foundation materials and another for the overlying tailings. (Authors.)

In view of the increasing demand in torque density, this article propounds the idea of looking for an upper bound of the torque production and average shear stress for surface permanent magnet (SPM) synchronous machines. The derivation is based on the assumption of an infinite permeability of the iron core and employs the transfer relation between the normal magnetic flux density and the tangential magnetic strength. The result is written as functions of the machine's major geometries and excitation conditions. The ratio of the actual value and this upper bound may be used as a metric of measuring the usage of materials’ electromagnetic capability, or reversely as an indicator of the marginal gain of the iron core of higher relative permeability. The result is further investigated to discuss the electromagnetic scalability and the sizing law of SPM machines. Specifically, the reason for increasing volumetric torque density as the machine size goes up is revealed. The optimal remanence flux density of permanent magnets is also predicted at 1.91T , providing that the lamination saturates at 2T ., Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public., DC systems, Energy conversion & Storage

Torsional moments and shear stresses are not calculated correctly in the framework analysis software SCIA Engineer for cross-sections with a shear centre eccentricity. The aim of this research is to analyze and solve this problem., Civil Engineering

Crushing machines are part of the charge departments of blast-furnace and steel-making shops of metallurgical enterprises. One of the main indicator of the crushing process is its energy efficiency. It is determined by the mass of crushed material when consuming a unit of electricity. The article considers various methods of crushing brittle materials and the design of crushing machines for their implementation. The analysis of the crushers has shown that impact crushers are the most energy-efficient. However, due to a significant drawback (the yield of a suitable product is very small), they are practically not used in the metallurgical industry, in which high requirements are imposed on the finished product fractional composition. In the metallurgical industry, compression crushers are widely used with approximately the same specific energy intensity, that is, with the same energy consumption for the destruction of a unit volume of material of equal strength. Compression fracture is the most energy-intensive crushing method known. In single-roll crushers, a piece of material is fed into the gap between a roll and a solid, stationary plate. During the operation, a complex stress state is generated in the destructed material. Compressive forces act on a piece of crushed material, causing normal compressive stresses in it, as well as an internal torque causing shear stresses. This is achieved by the reduction in energy on crushing by 20–30% in comparison with crushers operating in compression (all other things are equal). The authors describe the design of a crusher, in which the destruction of the processed material occurs due to the forces acting on the crushed piece in one plane towards each other. In this case, only shear stresses arise in the processed piece. The use of crushers, in which the destruction of the processed material occurs due to generation of only tangential stresses in a piece, can reduce the energy consumption per unit of finished product by alm

An extensive parametric study of turbulent boundary-layer control on airfoils via uniform blowing or suction is presented. The control is applied on either the suction or pressure side of several four-digit NACA-series airfoils. The considered parameter variations include angle of attack, Reynolds number, control intensity, airfoil camber, and airfoil thickness. Two comprehensive metrics, designed to account for the additional energy required by the control, are introduced to evaluate the net aerodynamic performance enhancements. The study confirms previous findings for suction-side boundary-layer control and demonstrates the interesting potential of blowing on the pressure side under various conditions, which achieves a maximum total net drag saving of 14% within the considered parameter space. The broad parameter space covered by the presented Reynolds-average Navier-Stokes simulations allows for more general conclusions than previous studies and can thus provide guidelines for the design of future detailed experimental or numerical studies on similar boundary-layer control schemes., QC 20211230

Liver sinusoids are lined by liver sinusoidal endothelial cells (LSEC), which represent approximately 15 to 20% of the liver cells, but only 3% of the total liver volume. LSEC have unique functions, such as fluid filtration, blood vessel tone modulation, blood clotting, inflammatory cell recruitment, and metabolite and hormone trafficking. Different subtypes of liver endothelial cells are also known to control liver zonation and hepatocyte function. Here, we have reviewed the origin of LSEC, the different subtypes identified in the liver, as well as their renewal during homeostasis. The liver has the exceptional ability to regenerate from small remnants. The past decades have seen increasing awareness in the role of non-parenchymal cells in liver regeneration despite not being the most represented population. While a lot of knowledge has emerged, clarification is needed regarding the role of LSEC in sensing shear stress and on their participation in the inductive phase of regeneration by priming the hepatocytes and delivering mitogenic factors. It is also unclear if bone marrow-derived LSEC participate in the proliferative phase of liver regeneration. Similarly, data are scarce as to LSEC having a role in the termination phase of the regeneration process. Here, we review what is known about the interaction between LSEC and other liver cells during the different phases of liver regeneration. We next explain extended hepatectomy and small liver transplantation, which lead to "small for size syndrome" (SFSS), a lethal liver failure. SFSS is linked to endothelial denudation, necrosis, and lobular disturbance. Using the knowledge learned from partial hepatectomy studies on LSEC, we expose several techniques that are, or could be, used to avoid the "small for size syndrome" after extended hepatectomy or small liver transplantation.

The lymphatic system is composed of a hierarchical network of fluid absorbing lymphatic capillaries and transporting collecting vessels. Despite distinct functions and morphologies, molecular mechanisms that regulate the identity of the different vessel types are poorly understood. Through transcriptional analysis of murine dermal lymphatic endothelial cells (LECs), we identified Foxp2, a member of the FOXP family of transcription factors implicated in speech development, as a collecting vessel signature gene. FOXP2 expression was induced after initiation of lymph flow in vivo and upon shear stress on primary LECs in vitro. Loss of FOXC2, the major flow-responsive transcriptional regulator of lymphatic valve formation, abolished FOXP2 induction in vitro and in vivo. Genetic deletion of Foxp2 in mice using the endothelial-specific Tie2-Cre or the tamoxifen-inducible LEC-specific Prox1-CreERT2 line resulted in enlarged collecting vessels and defective valves characterized by loss of NFATc1 activity. Our results identify FOXP2 as a new flow-induced transcriptional regulator of collecting lymphatic vessel morphogenesis and highlight the existence of unique transcription factor codes in the establishment of vessel-type-specific endothelial cell identities.

This paper presents the concept, design, construction, and validation of a novel probe based on the hexadic disposition of six pressure sensors suitable for measuring triaxial stress states inside bulky soft materials. The measurement of triaxial stress states inside bulk materials such as brain tissue surrogates is a challenging task needed to investigate internal organs’ stress states and validate FE models. The purpose of the work was the development and validation of a 17 × 17 × 17 mm probe containing six pressure sensors. To do so, six piezoresistive pressure sensors of 6 mm diameter were arranged into an hexad at three cartesian axes and bisecting angles, based on the analytical solution of the stress tensor. The resulting probe was embedded in a soft silicone rubber of known characteristics, calibrated under cyclic compression and shear in three orientations, and statically validated with combined loads. A calibration matrix was computed, and validation tests allowed us to estimate Von Mises stress under combined stress with an error below 6%. Hence, the proposed probe design and method can give indications about the complex stress state developing internally to soft materials under triaxial high-strain fields, opening applications in the analysis of biological models or physical surrogates involving parenchyma organs.

Vascular networks form, remodel and mature under the influence of multiple signals of mechanical or chemical nature. How endothelial cells read and interpret these signals, and how they integrate information when they are exposed to both simultaneously is poorly understood. Here, we show using flow-induced shear stress and VEGF-A treatment on endothelial cells in vitro, that the response to the magnitude of a mechanical stimulus is influenced by the concentration of a chemical stimulus, and vice versa. By combining different flow levels and different VEGF-A concentrations, front-rear polarity of endothelial cells against the flow direction was established in a flow and VEGF-A dose-response while their alignment with the flow displayed a biphasic response depending on the VEGF-A dose (perpendicular at physiological dose, aligned at no or pathological dose of VEGF-A). The effect of pharmaceutical inhibitors demonstrated that while VEGFR2 is essential for both polarity and orientation establishment in response to flow with and without VEGF-A, different downstream effectors were engaged depending on the presence of VEGF-A. Thus, Src family inhibition (c-Src, Yes, Fyn together) impaired alignment and polarity without VEGF-A while FAK inhibition modified polarity and alignment only when endothelial cells were exposed to VEGF-A. Studying endothelial cells in the aortas of VEGFR2(Y949F) mutant mice and SRCiEC-KO mice confirmed the role of VEGFR2 and specified the role of c-SRC in vivo. Endothelial cells of VEGFR2(Y949F) mutant mice lost their polarity and alignment while endothelial cells from SRCiEC-KO mice only showed reduced polarity. We propose here that VEGFR2 is a sensor able to integrate chemical and mechanical information simultaneously and that the underlying pathways and mechanisms activated will depend on the co-stimulation. Flow alone shifts VEGFR2 signaling toward a Src family pathway activation and a junctional effect (both in vitro and in vivo) while flow and

Cannulation strategies in medical treatment such as in extracorporeal life support along with the associated cannula position, orientation and design, affects the mixing and the mechanical shear stress appearing in the flow field. This in turn influences platelet activation state and blood cell destruction. In this study, a co-flowing confined jet similar to a return cannula flow configuration found in extracorporeal membrane oxygenation was investigated experimentally. Cannula diameters, flow rate ratios between the jet and the co-flow and cannula position were studied using Particle Image Velocimetry and Planar Laser Induced Fluorescence. The jet was turbulent for all but two cases, in which a transitional regime was observed. The mixing, governed by flow entrainment, shear layer induced vortices and a backflow along the vessel wall, was found to require 9-12 cannula diameters to reach a fully homogeneous mixture. This can be compared to the 22-30 cannula diameters needed to obtain a fully developed flow. Although not significantly affecting mixing characteristics, cannula position altered the development of the flow structures, and hence the shear stress characteristics., QC 20210326

The replacement of potentially hazardous synthetic dyes with natural dyes and pigments are of great interest for a sustainable economy. In order to obtain cost-efficient, environmentally friendly and competitive products, improvements in the cultivation and extraction of pigment-producing organisms and in dyeing processes are necessary. In our study, we were able to scale up the production of xylindein by Chlorociboria aeruginascens from 3 to 70 L bioreactor cultivations. We have identified important bioprocess parameters like low shear stress (150 rpm, tip speed <0.5 m/s) for optimal pigment yield (4.8 mg/L/d). Additionally, we have demonstrated the potential of laetiporic acid production by Laetiporus sulphureus in various cultivation systems and media, achieving dried biomass concentrations of almost 10 g/L with a 7 L bioreactor cultivation after 17 days. Extractions performed at 70°C and 15 min incubation time showed optimal results. To the best of our knowledge, we have described for the first time the use of this pigment in silk dyeing, which results in a brilliant hue that cannot easily be produced by other natural pigments. © 2020 The Authors. Engineering in Life Sciences published by Wiley-VCH GmbH

The homeostasis of vascular endothelium is crucial for cardiovascular health and endothelial cell (EC) aging and dysfunction could negatively impact vascular function. Leveraging transcriptome profiles from ECs subjected to various stimuli, including time-series data obtained from ECs under physiological pulsatile flow vs. pathophysiological oscillatory flow, we performed principal component analysis (PCA) to identify key genes contributing to divergent transcriptional states of ECs. Through bioinformatics analysis, we identified that a long non-coding RNA (lncRNA) RAMP2-AS1 encoded on the antisense of RAMP2, a determinant of endothelial homeostasis and vascular integrity, is a novel regulator essential for EC homeostasis and function. Knockdown of RAMP2-AS1 suppressed RAMP2 expression and caused EC functional changes promoting aging, including impaired angiogenesis and increased senescence. Our study demonstrates an integrative approach to quantifying EC aging based on transcriptome changes, which also identified a number of novel regulators, including protein-coding genes and many lncRNAs involved EC functional modulation, exemplified by RAMP2-AS1.

This is an Accepted Manuscript of an article published by Taylor & Francis Group in Road Materials and Pavement Design on 2021, available online at: http://www.tandfonline.com/10.1080/14680629.2021.1899966., The degree of adherence between two bituminous layers can be assessed from shear tests carried out at constant displacement speed, which allow the shear strength and stiffness of the interface to be obtained, being usual to specify a minimum strength. But stronger bonds will be more stressed, which could negatively affect their fatigue behaviour. In this work, the shear fatigue behaviour of two interfaces of different stiffness has been analysed, based on a cyclic compression test, performed at controlled stress, using the test device B described in the NLT-382 standard, included in the draft of the European pre-norm prEN 12697-48. From these tests, fatigue laws for each type of interface have been obtained. These laws, combined with a calculation method developed by the authors, have made it possible to obtain the number of cycles that each interface would withstand, under certain load hypotheses., Part of this study constitutes one of the activities carried out within the framework of the research project called SUPERBIT (Treatments for obtaining SUPERior properties and effectiveness of BITuminous coats to improve the durability of pavements) which has been included in the 2017 aid programme of the CDTI (Centre for Industrial Development and Technology), belonging to Ministry of Economy and Competitiveness of Spain. In addition, the authors would like to thank the company ARNÓ for the help received in carrying out the dynamic tests., Peer Reviewed, Postprint (author's final draft)

This article is focused on the derivation of constitutive equations for magnetic liquids. The results can be used for both ferromagnetic and magnetorheological fluids after the introduced simplifications. The formulation of constitutive equations is based on two approaches. The intuitive approach is based on experimental experience of non-Newtonian fluids, which exhibit a generally non-linear dependence of mechanical stress on shear rate; this is consistent with experimental experience with magnetic liquids. In these general equations, it is necessary to determine the viscosity of a liquid as a function of magnetic induction; however, these equations only apply to the symmetric stress tensor and can only be used for an incompressible fluid. As a result of this limitation, in the next part of the work, this approach is extended by the asymmetry of the stress tensor, depending on the angular velocity tensor. All constitutive equations are formulated in Cartesian coordinates in 3D space. The second approach to determining constitutive equations is more general: it takes the basis of non-equilibrium thermodynamics and is based on the physical approach, using the definition of density of the entropy production. The production of entropy is expressed by irreversible thermodynamic flows, which are caused by the effect of generalized thermodynamic forces after disturbance of the thermodynamic equilibrium. The dependence between fluxes and forces determines the constitutive equations between stress tensors, depending on the strain rate tensor and the magnetization vector, which depends on the intensity of the magnetic field. Their interdependencies are described in this article on the basis of the Curie principle and on the Onsager conditions of symmetry.

This article is focused on the derivation of constitutive equations for magnetic liquids. The results can be used for both ferromagnetic and magnetorheological fluids after the introduced simplifications. The formulation of constitutive equations is based on two approaches. The intuitive approach is based on experimental experience of non-Newtonian fluids, which exhibit a generally non-linear dependence of mechanical stress on shear rate; this is consistent with experimental experience with magnetic liquids. In these general equations, it is necessary to determine the viscosity of a liquid as a function of magnetic induction; however, these equations only apply to the symmetric stress tensor and can only be used for an incompressible fluid. As a result of this limitation, in the next part of the work, this approach is extended by the asymmetry of the stress tensor, depending on the angular velocity tensor. All constitutive equations are formulated in Cartesian coordinates in 3D space. The second approach to determining constitutive equations is more general: it takes the basis of non-equilibrium thermodynamics and is based on the physical approach, using the definition of density of the entropy production. The production of entropy is expressed by irreversible thermodynamic flows, which are caused by the effect of generalized thermodynamic forces after disturbance of the thermodynamic equilibrium. The dependence between fluxes and forces determines the constitutive equations between stress tensors, depending on the strain rate tensor and the magnetization vector, which depends on the intensity of the magnetic field. Their interdependencies are described in this article on the basis of the Curie principle and on the Onsager conditions of symmetry.