ShearVitroArteriesAneurysmsHemodynamicTurbulentVisualizationVelocityPumping the fluidPeriodicCharacteristicsMultiscaleCardiovascularHemodynamicsAneurysmVortexBlood flowReynoldsArteryMonolayerTurbulencePipeFrequencyPulse rateBiologicalNewtonianDecreasesParticle image velocStudyCellRatePressurePresentHighDeviceCurrentFormationSoundSimilar
Shear16
- We investigated whether atheroprotective unidirectional pulsatile shear stress affects the expression of PDCD4 in endothelial cells. (plos.org)
- En face co-immunostaining of the mouse aortic arch revealed a low level of PDCD4 in endothelial cells undergoing pulsatile shear stress. (plos.org)
- Application of unidirectional pulsatile shear stress to human umbilical vein endothelial cells (HUVECs) decreased PDCD4 protein but not mRNA level. (plos.org)
- Immunoprecipitation revealed that pulsatile shear stress induced the coupling of ubiquitin with PDCD4 expression. (plos.org)
- Low PDCD4 level was associated with reduced proliferation but not apoptosis or phosphorylation of endothelial nitric oxide synthase caused by pulsatile shear stress to help maintain the homeostasis of endothelial cells. (plos.org)
- Pulsatile shear stress induces ubiquitin-proteasome-mediated degradation of PDCD4 via a PI3K/Akt pathway in HUVECs. (plos.org)
- Low PDCD4 level is associated with reduced proliferation for maintenance of HUVEC homeostasis under pulsatile shear stress. (plos.org)
- Atherosclerosis plaques preferentially develop at arterial branches and curvatures under low and oscillatory or even static shear stress induced by disturbed blood flow as opposed to in straight parts, featuring protective unidirectional pulsatile shear stress [14] , [15] . (plos.org)
- Vascular endothelial cells, as a monolayer in direct contact with the flowing blood, bear the most of the wall shear stresses and have important homeostatic functions in response to stress [16] . (plos.org)
- Ample evidence shows that pro-atherosclerotic disturbed flow induces sustained activation of atherogenic genes in endothelial cells to promote their oxidation, inflammation, cell cycle progression and proliferation, whereas pulsatile shear stress tends to maintain endothelial cells in a quiescent and less proliferative state with a low level of oxidation and inflammation [16] , [17] . (plos.org)
- Various analytical expressions axial velocity, flow rate, wall shear stress and effective viscosity have been derived with the help of MATLAB for understanding the fluid flow phenomena. (scirp.org)
- Presence of atherosclerosis (stenosis), increased the resistance and therefore blood flow reduced inside the artery and also the remarkable change occurred in pressure distribution and wall shear stress. (scirp.org)
- High-resolution numerical simulations are carried out to systematically investigate the effect of the incoming flow waveform on the hemodynamics and wall shear stress patterns of an anatomic sidewall intracranial aneurysm model. (asme.org)
- At low PI, the flow in the dome is similar to a driven cavity flow and is characterized by a quasi-stationary shear layer that delineates the parent artery flow from the recirculating flow within the dome. (asme.org)
- Flow diversion may stimulate both routes, by augmenting particle residence time in the aneurysm, or by shear-induced platelet activation when blood is expulsed through the stent struts [ 7 ]. (springer.com)
- Non-Newtonian versus Numerical Rheology: Practical Impact Of Shear-thinning On The Prediction Of Stable And Unstable Flows In Intracranial Aneurysms. (simula.no)
Vitro1
- The object is to provide a device capable of reproducing in vitro, the exact pulsatile signals encountered in the blood vessels. (ni.com)
Arteries4
- The flow profiles was first derived by John R. Womersley (1907-1958) in his work with blood flow in arteries. (wikipedia.org)
- In recent years, the study of blood flow through obstructed arteries has received much attention, due to its ample importance in human cardiovascular system. (scirp.org)
- Since heart pumps of the blood are periodic in nature, the blood flow in narrow arteries can be assumed as pulsatile. (scirp.org)
- It represents actual noise created by structures near the ear such as noise generated by blood flowing through arteries or veins. (msdmanuals.com)
Aneurysms5
- The feasibility of using a compressed interwoven Supera stent as a flow diverting device for popliteal aneurysms was recently demonstrated in patients. (springer.com)
- It is unclear, however, what the optimal flow diverting strategy is, because of the fusiform shape of popliteal aneurysms and their exposure to triphasic flow. (springer.com)
- To assess this flow diverting strategy for popliteal aneurysms, flow profiles and thrombus formation likelihood were investigated in popliteal aneurysm models. (springer.com)
- In cerebral aneurysms, flow diverters effectively reduce flow in the aneurysm and promote aneurysm thrombosis and subsequent shrinkage [ 4 ]. (springer.com)
- Moreover, the system must enable to study different pulsatile hemodynamic patterns in different geometries such as aneurysms (a n aneurysm is a balloon-like expansion of weakened blood vessels which can rupture causing haemorrhages). (ni.com)
Hemodynamic1
- Liepsch [9] compared the details of flow behaviors with hemodynamic approach and observed that flow rate varies due to pulsatile nature of blood. (scirp.org)
Turbulent4
- In past experiments, simulations and theoretical analysis, rotation has been shown to dramatically effect the characteristics of turbulent flows, such as causing the mean velocity profile to appear laminar, leading to an overall drag reduction, as well as affecting the Reynolds stress tensor. (nsf.gov)
- The axially rotating pipe is an exemplary prototypical model problem that exhibits these complex turbulent flow physics. (nsf.gov)
- In this work, Direct Numerical Simulations (DNS) of rotating turbulent pipe flows are conducted at moderate Reynolds numbers (Re=5300, 11,700, and 19,000) and rotation numbers of N=0 to 3. (nsf.gov)
- The main objectives of this work are to firstly quantify turbulence suppression for rotating turbulent pipe flows at different Reynolds numbers as well as study the effects of rotation on turbulence by analyzing the characteristics of the Reynolds stress tensor and the production and dissipation terms of the turbulence budgets. (nsf.gov)
Visualization1
- Visualization of the valve and particle trajectories and simultaneous recording of sound, flow rate, and upstream and downstream pressure, provided direct evidence of the cause of many of the acoustical events. (caltech.edu)
Velocity5
- Note that, P 0 ′ {\displaystyle P'_{0}} (standing for n = 0 {\displaystyle n=0} ) is the steady-state pressure gradient, whose sign is opposed to the steady-state velocity (i.e., a negative pressure gradient yields positive flow). (wikipedia.org)
- The combined effect of catheterization, body acceleration, slip and inclination has been seen by plotting the graph and observed that axial velocity and flow rate increases with the increase in body acceleration, inclination angle and slip velocity while axial velocity diminishes on increasing the catheter radius. (scirp.org)
- All-electronic interrogation of biofluid flow velocity by electrical nanosensors incorporated in ultra-low-power or self-sustained systems offers the promise of enabling multifarious emerging research and applications. (nature.com)
- Alternatively, triboelectric charge harvested from a liquid flow by a micro/nanoelectrode device can be quantified for gauging the flow velocity. (nature.com)
- A flow of EDTA-anticoagulated whole bovine blood (pH = 7.0, ionic strength = 150 mM) with precisely controlled velocity was driven through the microfluidic channel by a syringe pump. (nature.com)
Pumping the fluid1
- The cardiovascular system of chordate animals is a very good example where pulsatile flow is found, but pulsatile flow is also observed in engines and hydraulic systems, as a result of rotating mechanisms pumping the fluid. (wikipedia.org)
Periodic3
- In fluid dynamics, a flow with periodic variations is known as pulsatile flow, or as Womersley flow. (wikipedia.org)
- Strouhal numbers were estimated from center-frequencies of resonance peaks associated with sounds that were related to periodic vortex shedding in flows past the struts, annular gaps and phonocatheter. (caltech.edu)
- Sud and Sekhon [5] studied on pulsatile flow of blood through a rigid circular tube subjected to periodic body acceleration considering blood as Newtonian fluid. (scirp.org)
Characteristics4
- Attention was given to understanding effects of valvar and pulsatile conditions upon the frequency characteristics of the opening, systolic, and closing sounds. (caltech.edu)
- A piston driven by a programmable DC servo motor was used to set-up a water flow system and provide the pulsation characteristics. (nsf.gov)
- However, existing nano-based electrical flow sensing technologies remain lacking in precision and stability and are typically only applicable to simple aqueous solutions or liquid/gas dual-phase mixtures, making them unsuitable for monitoring low-flow (~micrometer/second) yet important characteristics of continuous biofluids (such as hemorheological behaviors in microcirculation). (nature.com)
- In particular, over six-months stability and sub-micrometer/second resolution in real-time quantification of whole-blood flows with multiscale amplitude-temporal characteristics are obtained in a microfluidic chip. (nature.com)
Multiscale1
- Current topics include the modeling of blood flows in the cardiovascular system, the development of multiscale methods for the simulation of vascularized tissues and biomaterials. (wias-berlin.de)
Cardiovascular1
- The theoretical analysis on blood flow is very useful as it plays a significant role to diagnose and understand many cardiovascular diseases such as coronary thrombosis, angina, pectoris, strokes etc. (scirp.org)
Hemodynamics2
- We finally argue that the ratio between the characteristic time scale of transport by the mean flow across the neck and the time scale of vortex ring formation can be used to predict for a given sidewall aneurysm model the critical value of the waveform PI for which the hemodynamics will transition from the cavity mode to the vortex ring mode. (asme.org)
- How the Supera flow diverting configuration alters hemodynamics in a PAA has not yet been investigated. (springer.com)
Aneurysm9
- We show that the waveform PI is the key parameter that governs the vortex dynamics across the aneurysm neck and the flow patterns within the dome. (asme.org)
- At high PI, on the other hand, the flow is dominated by vortex ring formation, transport across the neck, and impingement and breakdown at the distal wall of the aneurysm dome. (asme.org)
- Six popliteal aneurysm models were created and integrated into a pulsatile flow set-up. (springer.com)
- Forward flow was optimally diverted, whereas backward flow was generally deflected into the aneurysm. (springer.com)
- A compressed Supera stent was successfully able to divert flow in a popliteal aneurysm phantom. (springer.com)
- Flow diverters are expected to decrease velocities in the aneurysm, but it is unknown whether this holds for PAA, where flow reversal, i.e. a diastolic retrograde flow, is typically present. (springer.com)
- Freezing Turbulence in Brain Aneurysm Flow Visualizations: An Applied Art-Science Collaboration. (simula.no)
- In the operating room, the patient was noted to have a large "pulsatile mass," which was determined to be an aneurysm. (medscape.com)
- A pulsation artifact, known as phase ghosting, indicates that flowing blood is present within the mass, which suggests that the mass could be an aneurysm. (medscape.com)
Vortex1
- Turbulence appears to be produced at the locations of maximum or minimum vorticity within the attached WVL, in the ridges between the K-H vortices around the separated WVL and the upstream side of the secondary vortex where the flow impinges on the wall. (nsf.gov)
Blood flow4
- Tu and Deville [2] observed the blood flow in diseased conditions. (scirp.org)
- MacDonald [14] considered the pulsatile blood flow in a catheterized artery and obtained theoretical estimates for pressure gradient corrections for catheters, which are positioned eccentrically, as well as coaxially with the artery. (scirp.org)
- For implementing blood-flow measurements, we fabricated acrylic chips with a graphene single-microelectrode device extending over the microfluidic channel (Fig. 1a ). (nature.com)
- An in-depth understanding of how blood flow is altered by different Supera stent configurations would help optimize its clinical application. (springer.com)
Reynolds2
- The Reynolds number varying from 200 to 500,000, and the valve opening degree varying from 20% to 100%, and the groove depth varying from 2.3 mm to 9 mm are chosen to investigate their effects on the flow and loss coefficients of the gate valve. (mdpi.com)
- The results show that the loss coefficient decreases and the flow coefficient increases with the increase of the Reynolds number and the valve opening degree, while with the increase of the groove depth, the loss coefficient barely changes, but the flow coefficient increases if the Reynolds number is larger than 10,000. (mdpi.com)
Artery2
- In this paper, the pulsatile flow of blood through an inclined catheterized stenosed artery is analyzed. (scirp.org)
- In this T1-weighted midline sagittal MR image without contrast, a flow void can be seen at the anterior edge of this mass, which represents the distal right posteriorinferior cerebellar artery. (medscape.com)
Monolayer2
- Here, we show that monolayer-graphene single microelectrodes harvesting charge from continuous aqueous flow provide an effective flow sensing strategy that delivers key performance metrics orders of magnitude higher than other electrical approaches. (nature.com)
- The flow transduction of the devices is based on a single microelectrode of monolayer graphene that harvests charge from flowing blood through contact electrification without the need for an external current supply. (nature.com)
Turbulence2
- The instability and transition to turbulence and its evolution in pulsatile flows, which involve reverse flows and unsteady flow separations, is the primary focus of this experimental work. (nsf.gov)
- The physical mechanisms causing turbulence suppression are currently not well-understood, and a deeper understanding of these mechanisms is of great value for many practical examples involving swirling or rotating flows, such as swirl generators, wing-tip vortices, axial compressors, hurricanes, etc. (nsf.gov)
Pipe1
- At higher Re numbers, the strength and extent of the vortices are larger and substantial disturbances appear in the free stream region of the flow, which are typical of pipe flows at transitional Re numbers. (nsf.gov)
Frequency1
- This PhD project aims at using low frequency (~10 Hz) oscillatory flows in liquids to develop a low-cost, simple and scalable platform for enriching and sorting particles. (findaphd.com)
Pulse rate1
- Effects of pulse rate, mean flow-rate, and mean aortic pressure associated with the normal valvar sounds were investigated. (caltech.edu)
Biological1
- Further research concentrates on the development, the analysis, and the simulation of mathematical models for a better understanding of biological flows and biological tissues. (wias-berlin.de)
Newtonian1
- The liquids used will exhibhit Newtonian flow (e.g. water) and non-Newtonian flow (e.g. cornstarch solution) properties. (findaphd.com)
Decreases1
- Bennett [1] has observed that the presence of wall slip at the flow boundaries decreases the apparent (effective) viscosity. (scirp.org)
Particle image veloc1
- Two-dimensional flow velocities were visualized by laser particle image velocimetry. (springer.com)
Study1
- A key aspect of this project will be to study the interaction of deformable particles with liquid flow. (findaphd.com)
Cell1
- This ability should enable signals to be generated and applied to ECs (endothelial cells) or bilayer culture systems containing ECs and VSMCs ( vascular smooth muscle cells) seeded in a transparent test chamber or any geometry that allows observation under the microscope, recording of flow parameters and cell harvest after treatments. (ni.com)
Rate2
- Under alternate pulsatile states, the total power of the opening and closing sounds were influenced primarily by the rate of change of the ventricular pressure prior to these events. (caltech.edu)
- An increase in systolic flow rate produced a corresponding increase in the power of peaks in the spectra of the systolic sound for each design. (caltech.edu)
Pressure2
Present1
- A flow void originating from the right PICA was present on midline sagittal T1-weighted images (Figure 2). (medscape.com)
High1
- An alternative strategy is the use of a flow diverting stent, i.e. a bare stent with high strut density. (springer.com)
Device1
- The devices deliver a resolution of 0.49 ± 0.01 µm s −1 (in a 1-Hz bandwidth), a two-orders-of-magnitude improvement compared with existing device-based flow-sensing approaches, and are ultrathin (one-atom-layer) and of low risk of being fouled or causing channel clogging. (nature.com)
Current1
- Here, we show self-powered graphene microdevices that transduce in real time the flow of continuous blood in a microfluidic channel to charge-transfer current in response to the flow-sensory rearrangement (not formation/deformation) of EDL at the graphene-aqueous interface. (nature.com)
Formation1
- Inflectional instability leads to flow separation and the formation of a major roll-up structure with the K-H vortices superimposed. (nsf.gov)
Sound1
- In such cases, the sound comes with each beat of the pulse (pulsatile). (msdmanuals.com)
Similar1
- The location of peaks within the power density spectra of opening, systolic and closing sounds were more similar during the studies of alternate, non-normal, pulsatile states of normal valves than they were during the studies of normal/abnormal valves under normal pulsatile states. (caltech.edu)