scholarly journals Flow Rate through a Blood Vessel Deformed Due To a Uniform Pressure

2011 ◽  
Vol 02 (04) ◽  
pp. 369-377 ◽  
Author(s):  
Amy Cypher ◽  
J Mohamed B. Elgindi ◽  
Hatem Kouriachi ◽  
David Peschman ◽  
Reba Shotwell
Keyword(s):  
Blood Vessel ◽  
Flow Rate ◽  
Uniform Pressure

scholarly journals The Need of Slanted Side Holes for Venous Cannulae

2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Joong Yull Park
Keyword(s):  
Numerical Modeling ◽  
Shear Rate ◽  
Blood Vessel ◽  
Penetration Depth ◽  
Flow Rate ◽  
Analysis Study ◽  
Side Hole ◽  
Good Flow

Well-designed cannulae must allow good flow rate and minimize nonphysiologic load. Venous cannulae generally have side holes to prevent the rupture of blood vessel during perfusion. Optimizing side hole angle will yield more efficient and safe venous cannulae. A numerical modeling was used to study the effect of the angle (0°–45°) and number (0–12) of side holes on the performance of cannulae. By only slanting the side holes, it increases the flow rate up to 6% (in our models). In addition, it was found that increasing the number of side holes reduces the shear rate up to 12% (in our models). A new parameter called “penetration depth” was introduced to describe the interfering effect of stream jets from side holes, and the result showed that the 45°-slanted side holes caused minimum interfering for the flow in cannula. Our quantitative hemodynamic analysis study provides important guidelines for venous cannulae design.

Numerical Investigation for the Effect of Blood Flow Rate and Asymmetric Bifurcation Angle on the Anterior Circulation Aneurysm Formation

2011 ◽  
Author(s):  
Soyoon Kim ◽  
Kyoungchul Ro ◽  
Hong Sun Ryou
Keyword(s):  
High Pressure ◽  
Blood Flow ◽  
Blood Vessel ◽  
Flow Rate ◽  
Rate Ratio ◽  
Arterial Wall ◽  
Blood Flow Rate ◽  
Flow Rate Ratio ◽  
Anterior Circulation ◽  
Bifurcation Angle

Most of aneurysms in the cranial cavity occur at the bifurcation of anterior circulation system. A cerebral aneurysm is easily ruptured, and it is fatal for most patients. Generally it is known that aneurysm occurs when arterial wall is deformed by high pressure or high wall shear stress (WSS). A blood flow pattern and the geometry and the blood vessel are important factors for aneurysm formation and the location. The transient interaction between blood flow and the arterial wall affects for simulating deformation of the blood vessel. Thus, numerical analysis is performed for various bifurcation angles and flow rate ratio in bifurcation artery with different diameters to predict the location of aneurysm by hemodynamic characteristics of blood flow. A bifurcation angle between the internal carotid artery and the anterior cerebral artery (ACA) increased, a region of high pressure moved to the bifurcated artery with larger bifurcation angle when ratio of blood flow rate is constant case. When the ratio of blood flow increased, the region of high wall shear stress moved to the side of large flow rate ratio. Our results showed that the high WSS or high pressure region occur at the location of aneurysm as mentioned in the clinical research. Thus, this indicates that the geometry of blood vessel and blood flow rate affect the location of the anterior circulation aneurysm.

Modification of lymph by lymph nodes. III. Effect of increased lymph hydrostatic pressure

1985 ◽  
Vol 249 (4) ◽  
pp. H777-H782 ◽  
Author(s):  
T. H. Adair ◽  
A. C. Guyton
Keyword(s):  
Steady State ◽  
Hydrostatic Pressure ◽  
Blood Vessel ◽  
Lymph Nodes ◽  
Flow Rate ◽  
Protein Concentration ◽  
Lymph Flow ◽  
Blood Capillary ◽  
Fluid Exchange ◽  
Very High

Previous studies have shown that lymph nodes function as fluid exchange chambers in which the protein concentration of lymph is changed in the direction required to establish equilibrium of the Starling forces acting across the nodal blood-lymph barrier. We examined the effect of increased lymph hydrostatic pressure on efferent lymph by use of an isolated dog popliteal node preparation in which lymph having a protein concentration averaging 27.6 +/- 1.2% (SD) of that of plasma was infused into the node at a flow rate averaging 45.6 +/- 0.2 (SD) microliter/min. We compared steady-state values of prenodal and postnodal lymph flow and protein concentration following step increases in efferent lymph pressure from 0 to over 15 mmHg. Increasing efferent lymph pressure to values less than about 8 mmHg caused the efferent lymph protein concentration to increase; however, further increases in lymph pressure caused the lymph protein concentration to decrease to values approaching those attained at very low lymph pressures. We suggest that the failure of high lymph pressure to increase lymph protein concentration might be caused by blood vessel collapse within the node, a condition believed to increase nodal blood capillary pressure and to decrease blood-lymph barrier filtration coefficient. An important finding was that increasing efferent lymph pressure caused significant amounts of lymph proteins to be lost during nodal transit. Therefore, it appears that increasing efferent lymph pressure to very high values has little effect on lymph protein concentration but has great effect on postnodal lymph protein flux.

scholarly journals Application of Non-thermal Commscope Irradiation in Preventing Com- plications of Hemodialysis Fistula

1970 ◽  
Vol 1 (1) ◽  
Author(s):  
Leng Hui
Keyword(s):  
Blood Flow ◽  
Blood Vessel ◽  
Arteriovenous Fistula ◽  
Flow Rate ◽  
Blood Flow Rate ◽  
Hemodialysis Patients ◽  
First Choice ◽  
Long Time ◽  
And Control

Abstract: Objective: To ensure that the patient’s treatment and control of the patient’s blood in the course of long-term dialysis, in order to ensure the blood flow rate at the rate of hemodialysis in the blood vessel of hemodialysis patients, mortality rate. Methods: In many Western countries, it has been found from the experience of long-term accumulation, arteriovenous fistula (AVF) is the first choice for long-term dialysis blood patients, which has a lot of a little bit, not only from the infection rate and blood flow, which has a lot of advantages.But its existence is also a lot of complications, non-thermal Commscope irradiation is a very effective way. Results: The method was compared with the method, and it was found that P <0.05, which was statistically significant. Conclusion: AVF is the preferred method of vascular access in patients with persistent dialysis, which is very easy to be punctured and has a very long time for maintenance. It is very important to carry out the treatment, treatment and surveillance of AVF complications and the use of means.

Hydrodynamic Modeling of Targeted Magnetic-Particle Delivery in a Blood Vessel

2013 ◽  
Vol 135 (3) ◽  
Author(s):  
Huei Chu Weng
Keyword(s):  
Magnetic Field ◽  
Blood Vessel ◽  
Flow Rate ◽  
Magnetic Fluid ◽  
Magnetic Particles ◽  
Magnetic Particle ◽  
Volume Fraction ◽  
Hydrodynamic Modeling ◽  
Flow Drag ◽  
Particle Delivery

Since the flow of a magnetic fluid could easily be influenced by an external magnetic field, its hydrodynamic modeling promises to be useful for magnetically controllable delivery systems. It is desirable to understand the flow fields and characteristics before targeted magnetic particles arrive at their destination. In this study, we perform an analysis for the effects of particles and a magnetic field on biomedical magnetic fluid flow to study the targeted magnetic-particle delivery in a blood vessel. The fully developed solutions of velocity, flow rate, and flow drag are derived analytically and presented for blood with magnetite nanoparticles at body temperature. Results reveal that in the presence of magnetic nanoparticles, a minimum magnetic field gradient (yield gradient) is required to initiate the delivery. A magnetic driving force leads to the increase in velocity and has enhancing effects on flow rate and flow drag. Such a magnetic driving effect can be magnified by increasing the particle volume fraction.

Determination of the Mass-Flow Rate of Blood in a Blood Vessel Using Natural Frequencies of Flexural Vibrations

2020 ◽  
Vol 65 (5) ◽  
pp. 190-193
Author(s):  
V. M. Timerbulatov ◽  
Sh. V. Timerbulatov ◽  
A. G. Khakimov
Keyword(s):  
Blood Vessel ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Natural Frequencies ◽  
Flexural Vibrations

Numerical Simulation of the Effects of a Thermally Significant Blood Vessel on Freezing by a Circular Surface Cryosurgical Probe Compared With Experimental Data

2009 ◽  
Vol 131 (5) ◽  
Author(s):  
Genady Beckerman ◽  
Avraham Shitzer ◽  
David Degani
Keyword(s):  
Experimental Data ◽  
Blood Vessel ◽  
Cooling Rate ◽  
Flow Rate ◽  
Freezing Point ◽  
Cylindrical Tube ◽  
Operating Conditions ◽  
Inlet Temperature ◽  
Cooling Rates ◽  
Flow Rates

The dynamic thermal interaction between a surface cryosurgical probe (heat sink) and an embedded cylindrical tube (heat source), simulating a thermally-significant blood vessel, has been studied. The cryoprobe was operated by liquid nitrogen while the embedded tube was perfused by water at a constant inlet temperature. Previous experimental data were obtained in a phase-changing medium (PCM) made of 30%/70% by volume mashed potato flakes/distilled-water solution. A parametric study was conducted without the embedded tube, and with flow rates of 30 ml/min and 100 ml/min in the tube, while cooling rates at the tip of the cryoprobe were maintained at −4°C/min, −8°C/min, or −12°C/min. Numerical thermal analysis was performed by ANSYS7.0 and showed good conformity to the experimental data. The results quantify the effects of these parameters on both the shape and extent of freezing obtained in the PCM. For 20 min of operation of the cryoprobe, water temperatures inside the tube remained well above the freezing point for all assumed operating conditions. Frozen volumes of the 0°C isotherm, approximating the “frozen front,” and the −40°C isotherm, representing the “lethal temperature,” were smallest for the combination of highest cooling rate at the cryoprobe and the highest flow rate in the tube, (−12°C/min and 100 ml/min). The results indicate that both the flow rates in the embedded tube, and the cooling rates applied at the cryoprobe, have similar qualitative effects on the size of the PCM frozen volumes; increasing either one will cause these volumes to decrease. Under the conditions of this study the effects of flow rate in the tube are more pronounced, however, effecting relative frozen volumes decreases by about 10–20% while those of the cooling rate at the cryoprobe are in the range of 7–14%.

An Ultrastructural Study of Pericytes

1968 ◽  
Vol 26 ◽  
pp. 66-67
Author(s):  
T. M. Murad ◽  
E. von Haam
Keyword(s):  
Plasma Membrane ◽  
Endothelial Cell ◽  
Basement Membrane ◽  
Blood Vessel ◽  
Vascular Endothelial Cells ◽  
Myoepithelial Cells ◽  
Capillary Blood ◽  
The Body ◽  
Capillary Blood Vessel ◽  
Outer Plasma Membrane

Pericytes are vascular satellites present around capillary blood vessels and small venules. They have been observed in almost every tissue of the body and are thought to be related to vascular smooth muscle cells. Morphologically pericytes have great similarity to vascular endothelial cells and also slightly resemble myoepithelial cells.The present study describes the ultrastructural morphology of pericytes in normal breast tissue and in benign tumor of the breast. The study showed that pericytes are ovoid or elongated cells separated from the endothelial cell of the capillary blood vessel by the basement membrane of endothelial cell. The nuclei of pericytes are often very distinctive. Although some are round, oval, or elongated, others show marked irregularity and infolding of the nuclear membrane. The cytoplasm shows mono-or bipolar extension in which the cytoplasmic organelles are located (Fig. 1). These cytoplasmic extensions embrace the capillary blood vessel incompletely. The plasma membrane exhibits multiple areas of focal condensation called hemidesmosomes (Fig. 2, arrow). A variable number of pinocytotic vesicles are frequently seen lining the outer plasma membrane. Normally pericytes are surrounded by a basement membrane which is found more consistently on the outer plasma membrane separating the pericytes from the stromal connective tissue.

A Novel Reconstitution Method for Inducing the Formation of Regular 2-Dimensional Arrays of Membrane Proteins and Lipids

1988 ◽  
Vol 46 ◽  
pp. 152-153 ◽  
Author(s):  
A. Engel ◽  
A. Holzenburg ◽  
K. Stauffer ◽  
J. Rosenbusch ◽  
U. Aebi
Keyword(s):  
Membrane Proteins ◽  
Flow Rate ◽  
Lipid Membranes ◽  
Functional Characterization ◽  
Dimensional Structure ◽  
Electron Crystallography ◽  
Peltier Element ◽  
Protein Ratio ◽  
Precise Control ◽  
3 Dimensional

Reconstitution of solubilized and purified membrane proteins in the presence of phospholipids into vesicles allows their functions to be studied by simple bulk measurements (e.g. diffusion of differently sized solutes) or by conductance measurements after transformation into planar membranes. On the other hand, reconstitution into regular protein-lipid arrays, usually forming at a specific lipid-to-protein ratio, provides the basis for determining the 3-dimensional structure of membrane proteins employing the tools of electron crystallography.To refine reconstitution conditions for reproducibly inducing formation of large and highly ordered protein-lipid membranes that are suitable for both electron crystallography and patch clamping experiments aimed at their functional characterization, we built a flow-dialysis device that allows precise control of temperature and flow-rate (Fig. 1). The flow rate is generated by a peristaltic pump and can be adjusted from 1 to 500 ml/h. The dialysis buffer is brought to a preselected temperature during its travel through a meandering path before it enters the dialysis reservoir. A Z-80 based computer controls a Peltier element allowing the temperature profile to be programmed as function of time.

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