Preliminary Imaging of Red Blood Cells in Turbulent Flow

2012 ◽  
Author(s):  
Mostafa Shakeri ◽  
Iman Khodarahmi ◽  
M. Keith Sharp
Keyword(s):  
Turbulent Flow ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Imaging System ◽  
Navier Stokes ◽  
Viscous Stress ◽  
Damage Potential ◽  
Navier Stokes Equation ◽  
Considerable Uncertainty ◽  
Mathematical Construct

Considerable uncertainty exists about how momentum and energy are transferred to cells in turbulent flow, which has been shown to cause six times more damage to red blood cells (RBC’s) than laminar flow with the same mean wall shear stress [Kameneva, et al. 2004]. Though it is a purely mathematical construct to yield closure of the time-averaged Navier-Stokes equation for a continuum fluid, which is not valid at the scale of the cell, Reynolds stress has been used as an empirical indicator for damage potential [Sallam & Hwang 1984]. Other scales, including local viscous stress [Jones 1995], flow of plasma around inertia cells [Quinlan & Dooley 2007], shear within eddies [Quinlan & Dooley 2007] and shear between rigid cells within an eddy [Antiga & Steinman 2009], have been forwarded. To provide data to validate these models, an imaging system was assembled to directly observe RBC’s in turbulent flow under a microscope.

The Reynolds Stress in Channel Flows From a Lagrangian Treatment of the Turbulence Momentum

2019 ◽  
Author(s):  
T.-W. Lee
Keyword(s):  
Turbulent Flow ◽  
Reynolds Stress ◽  
Current Approach ◽  
Navier Stokes ◽  
Current Transport ◽  
Lagrangian Analysis ◽  
Navier Stokes Equation ◽  
Mechanistic Approach ◽  
Turbulent Momentum

Abstract We have developed a mechanistic approach for determination of the Reynolds stress, using a Lagrangian analysis of turbulent momentum. Analysis and comparison with DNS and experimental data point toward the soundness of this approach (Lee, 2018). von Karman constant, the inner layer thickness and the Reynolds stress itself are all recovered through this approach, in agreement with DNS data. In addition, the turbulent flow profiles can be calculated iteratively using the basic Reynolds-averaged Navier-Stokes equation, in conjunction with the current transport equation for the Reynolds stress. In this work, we explore these and further uses of the current approach in solving turbulent flow dynamics.

Validation of the INS3D-UP Code in the Prediction of Turbulent Flow of Liquid Propellants in a Sharp Bend

1995 ◽  
Author(s):  
M. A. R. Sharif ◽  
J. T. Haskew
Keyword(s):  
Turbulent Flow ◽  
Space Shuttle ◽  
Circular Cross Section ◽  
Navier Stokes ◽  
Navier Stokes Equation ◽  
Sharp Bend ◽  
Flow Problems ◽  
Fortran Code ◽  
Main Engine ◽  
Liquid Propellants

Abstract The capability of the INS3D-UP code in the prediction of turbulent flow in a sharp bend of circular cross-section has been investigated. The code, developed by the NASA Ames Research Center, is being used by the NASA Marshal Space Flight Center to analyze turbulent flow of liquid propellant in vaned pipe bends designed for use in the Space Shuttle Main Engine. The FORTRAN code is based on finite difference method and uses the concept of pseudocompressibility to solve incompressible Navier-Stokes equation. The Baldwin-Barth turbulence model is embedded in the code for turbulence computation. The flow field, at a Reynolds number of 43,000, in a sharp 90° bend has been predicted and compared with measurement. It is found that the agreement between the predicted and measured velocities is very well. The predicted pressures at the bend wall also compares reasonably well with the measurement. It is concluded that the INS3D-UP code is a good computational tool to analyze similar flow problems.

RAP-536 Accelerates Recovery From Chemotherapy-Induced Anemia (CIA) without Promoting Tumor Growth In Murine Models of Cancer and CIA

Blood ◽  
2010 ◽  
Vol 116 (21) ◽  
pp. 4230-4230
Author(s):  
Samuel M. Cadena ◽  
Rajasekhar NVS Suragani ◽  
Dianne Mitchell ◽  
Jeff Ucran ◽  
Katia Liharska ◽  
...  
Keyword(s):  
Tumor Growth ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Imaging System ◽  
Luciferase Reporter ◽  
Soluble Form ◽  
Mouse Tumor ◽  
Blood Samples ◽  
Extracellular Region ◽  
To Receive

Abstract Abstract 4230 We have previously shown that administration of ACE-536, a soluble form of a modified activin type IIB receptor, is an effective therapy in both acute and chronic animal models of anemia. We have further demonstrated that ACE-536 induces red cell development by promoting late stage erythroblast maturation. Anemia is a debilitating complication associated with several chronic diseases, including cancer, and is exacerbated by the use of cancer chemotherapy. Recombinant human erythropoietin (EPO) is the most commonly prescribed treatment for chemotherapy induced anemia. However, there is increasing evidence to suggest that the administration of EPO may accelerate tumor growth by promoting angiogenesis. Therefore, non-EPO based strategies to correct chemotherapy induced anemia without effects on underlying tumor are needed. Several members of the TGF-β superfamily have been shown to be involved in red blood cell production. We have developed ACE-536 as a modified form of the extracellular region of the activin type IIB receptor fused to the Fc region of human IgG1, which binds to and inhibits several ligands in the TGF-β superfamily. Here we report on the effects of RAP-536, a murine analog of ACE-536 containing the modified extracellular region of the activin type IIB receptor fused to the Fc region of a murine IgG, in rodent models of chemotherapy induced anemia and tumor growth. To evaluate the efficacy of RAP-536 in a rodent model of chemotherapy induced anemia 300 g Sprague-Dawley rats were administered a single intravenous dose of carboplatin (75 mg/kg) or phosphate-buffered saline (PBS). Blood samples were taken twice weekly to assess the induction of carboplatin induced anemia. By Day 11 rats treated with carboplatin showed an average drop of 34%, 32% and 36% in red blood cells, hemoglobin and hematocrit, respectively, and were randomized to receive RAP-536 twice weekly at a dose of 10 mg/kg or an equal volume of tris-buffered (TBS). Blood samples were taken twice weekly to evaluate recovery from anemia. Rats treated with RAP-536 exhibited a more rapid rate of recovery (ANOVA; P < 0.001) than those treated with TBS. Moreover, at study termination (Day 35), red blood cells, hemoglobin and hematocrit levels of RAP-536 treated rats were 28%, 23% and 23% greater, respectively, than TBS-treated controls (P < 0.01). EPO administration has previously been shown to accelerate the rate of tumor growth in a mouse tumor bearing model; therefore, we sought to investigate the effect of RAP-536 in this context. Eight-week old mice were injected subcutaneously in the right hind flank with 3×105 Lewis lung carcinoma cells expressing a luciferase reporter. Mice were randomized to receive weekly subcutaneous injections of TBS, RAP-536 (10 mg/kg) or EPO (200 U/kg). Tumor growth was assessed twice weekly by manual external caliper measurements and once weekly by luciferase activity using an IVIS in vivo imaging system. Tumors in EPO treated mice grew at a moderately accelerated rate compared to TBS and RAP-536 treated mice; however, this was not statistically significant. At study termination tumors were excised and weighed. Mice treated with EPO showed statistically significant larger tumors compared to TBS treated animals (P = 0.0126). On the other hand, mice treated with RAP-536 did not show statistically significant increases in tumor size (P = 0.1689). In conclusion, targeting the TGF-β signaling pathway with RAP-536 is a viable therapeutic approach for the treatment of anemia induced by chemotherapy treatment and may represent a safer alternative to EPO-based therapies. Disclosures: Cadena: Acceleron Pharma: Employment. Suragani:Acceleron Pharma: Employment. Mitchell:Acceleron Pharma: Employment. Ucran:Acceleron Pharma: Employment. Liharska:Acceleron Pharma: Employment. Sako:Acceleron Pharma: Employment. Monnell:Acceleron Pharma: Employment. Underwood:Acceleron Pharma: Employment. Kumar:Acceleron Pharma: Employment. Pearsall:Acceleron Pharma: Employment.

Depletion of Red Blood Cells from Cord Blood Using a Simple and Rapid Immunomagnetic Separation Method

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 3853-3853
Author(s):  
Ben S Lam ◽  
Albertus W Wognum ◽  
Terry E Thomas ◽  
Allen C Eaves ◽  
Stephen J Szilvassy
Keyword(s):  
Cord Blood ◽  
Red Blood Cells ◽  
Blood Cells ◽  
Magnetic Particles ◽  
Bone Marrow Cells ◽  
Imaging System ◽  
Immunomagnetic Separation ◽  
Small Samples ◽  
Hematopoietic Stem ◽  
High Background

Abstract Cord blood (CB) banks and transplantation centers routinely use various assays to measure the number and quality of hematopoietic stem and progenitor cells (HSPC) in hematopoietic cell samples before or after cryopreservation and/or transplantation. Such assays, to measure colony-forming units (CFU) and CD34+/ALDHbright cells, for example, are typically performed on small samples, such as attached segments from frozen CB units. Unfortunately, the accuracy and reliability of these assays are highly sensitive to the presence of contaminating red blood cells (RBCs) in the sample. Current methods for depleting RBCs for downstream analysis include sedimentation by gravity or by centrifugation through density gradient solutions, and hemolysis using ammonium chloride. These procedures are, however, time consuming and may be associated with reduced yield of HSPCs. To address these issues, we have developed a simple and rapid immunomagnetic method (ErythroClear) for depleting RBCs in fresh and thawed CB. RBCs in small (≤100 µL) CB samples are labeled with anti-Glycophorin-A (GlyA) antibodies immobilized on magnetic particles, and removed by magnetic separation. The method allows the handling of multiple samples at one time and takes only 2 minutes per sample. Compared to sedimentation methods using either HetaSep or PrepaCyte, which take 20 minutes per sample, ErythroClear is significantly more effective in depleting RBCs from CB, producing a final purity of 78% GlyAB-CD45+ cells compared to 11% with HetaSep and 9% with PrepaCyte (paired t-test, p<2.9x10-9 and p<3.6x10-9 respectively; n=8). To determine the effect of ErythroClear on the frequency of progenitors, CD34+/ALDHbright cells and CFUs were enumerated in CB samples before and after RBC depletion. The frequencies of CD34+, ALDHbright, and CD34+ALDHbright progenitors in fresh CB remained essentially unchanged following RBC depletion (p=0.75; n=6). Similarly, the frequency of CFUs measured by colony formation in MethoCult H4434 medium was not significantly altered after RBC depletion of fresh (p=0.16; n=11) and previously frozen CB (p=0.21; n=10) samples. RBC depletion using ErythroClear facilitated accurate counting of colonies using STEMvision, an imaging system for automated identification, classification, and enumeration of CFU assays of human blood or bone marrow cells. While automated colony counts differed significantly from manual counts for CFU assays with a high background of RBCs (p<0.02 for frozen-thawed CB [n=10]; p<0.01 for fresh CB [n=11]), very similar CFU numbers were obtained with both colony counting methods for samples in which RBCs were removed using ErythroClear (p=0.32 for thawed CB [n=10]; p=0.24 for fresh CB [n=11]). Taken together, these findings demonstrate that RBCs can be effectively removed from small CB samples by immunomagnetic removal of GlyA+ cells without affecting the frequency of HSPCs, and highlight the importance of depleting RBCs to ensure accurate and reliable enumeration of progenitors in CB samples. Disclosures Lam: STEMCELL Technologies Inc.: Employment. Wognum:STEMCELL Technologies Inc.: Employment. Thomas:STEMCELL Technologies Inc.: Employment. Eaves:STEMCELL Technologies Inc.: CEO and Owner Other. Szilvassy:STEMCELL Technologies Inc.: Employment.

CFD Simulation of Coaxial Jet Mixer Using RANS Turbulent Models

2012 ◽  
Vol 326-328 ◽  
pp. 416-421 ◽  
Author(s):  
Ku Zilati Ku Shaari ◽  
Afiq Mohd Laziz ◽  
Kerstin Heinen ◽  
Mokhtar Awang ◽  
Suriati Sufian ◽  
...  
Keyword(s):  
Turbulent Flow ◽  
Cfd Simulation ◽  
Navier Stokes ◽  
Suitable Model ◽  
Navier Stokes Equation ◽  
Rans Model ◽  
Turbulent Models ◽  
Simulation Time ◽  
Selection Of ◽  
Good Agreement

The Reynolds Averaged Navier Stokes Equation (RANS) model was used to describe the turbulent flow in a coaxial jet mixer. The effects of turbulent models on the turbulent flow is investigated to help the engineers and researchers in deciding the selection of turbulent model need to be used in order to save the simulation time and to predict the best suitable model to be used. Good agreement of the CFD prediction with the experimental data in certain locations was obtained with species transport and velocity profiled, where dependence of turbulent models and grid sizes were discussed in detail. The results show that, the need of grid study is crucial to obtain reliable results with optimum consumption of computer power. SST and Launder Gibson RSTM models give results superior to the other models, each of which has its own area of capability. Launder Gibson RSTM is good in predicting the flow with recirculation and vortices, while SST is good for the flow with less recirculation and high velocity. The overall results show that RANS model is capable in predicting the area of mixing and the velocity profile correctly in certain locations but not in reproducing the vortices structure in the pipe and nozzle.

scholarly journals The concept of turbulent «vortex backfill» - models and methods. Power engineering: research, equipment, technology

2019 ◽  
Vol 21 (5) ◽  
pp. 97-109
Author(s):  
L. E. Melamed ◽  
G. A. Filippov
Keyword(s):  
Turbulent Flow ◽  
Numerical Solutions ◽  
Turbulent Viscosity ◽  
Internal Resistance ◽  
Navier Stokes ◽  
Flow Profile ◽  
Navier Stokes Equation ◽  
Engineering Research ◽  
Turbulent Vortex ◽  
Fluctuation Method

Models and methods for studying turbulence based on the concept of turbulent "vortex backfill" are presented. The essence of this concept is that the turbulent flow is considered as laminar, flowing through a "vortex backfill ", which creates internal resistance. This resistance can be considered either as distributed, or as locally concentrated. Based on the first representation, a modified Navier-Stokes equation, its approximate analytical and numerical solutions are obtained. Based on the second concept and the local fluctuation method developed for these purposes, a computer model of the turbulent flow in the pipes is obtained. Using simulation, it is shown that, when a certain system of local viscosity fluctuations is specified, the calculated flow profile corresponds to the profile of the turbulent flow velocity. The magnitude and profile of the turbulent viscosity of the flow are completely determined by the structure and properties of the "vortex backfill ". The results of the work confirm the possibility and efficiency of considering turbulence based on this concept.

Numerical Modeling of Pulsatile Turbulent Flow in Stenotic Vessels

2003 ◽  
Vol 125 (4) ◽  
pp. 445-460 ◽  
Author(s):  
Sonu S. Varghese ◽  
Steven H. Frankel
Keyword(s):  
Reynolds Number ◽  
Turbulent Flow ◽  
Turbulence Model ◽  
Turbulence Models ◽  
Navier Stokes ◽  
Mean Flow ◽  
Navier Stokes Equation ◽  
Flow Through ◽  
The Mean ◽  
High Reynolds

Pulsatile turbulent flow in stenotic vessels has been numerically modeled using the Reynolds-averaged Navier-Stokes equation approach. The commercially available computational fluid dynamics code (CFD), FLUENT, has been used for these studies. Two different experiments were modeled involving pulsatile flow through axisymmetric stenoses. Four different turbulence models were employed to study their influence on the results. It was found that the low Reynolds number k-ω turbulence model was in much better agreement with previous experimental measurements than both the low and high Reynolds number versions of the RNG (renormalization-group theory) k-ε turbulence model and the standard k-ε model, with regard to predicting the mean flow distal to the stenosis including aspects of the vortex shedding process and the turbulent flow field. All models predicted a wall shear stress peak at the throat of the stenosis with minimum values observed distal to the stenosis where flow separation occurred.

Computational simulation of turbulent flows around a marine propeller by solving the partially averaged Navier–Stokes equation

2019 ◽  
Vol 233 (18) ◽  
pp. 6357-6366
Author(s):  
Woochan Seok ◽  
Sang Bong Lee ◽  
Shin Hyung Rhee
Keyword(s):  
Turbulent Flow ◽  
Reynolds Stress ◽  
Stokes Equation ◽  
Leading Edge ◽  
Reynolds Stress Model ◽  
Navier Stokes ◽  
Stress Model ◽  
Navier Stokes Equation ◽  
Local Flow ◽  
Reynolds Averaged Navier Stokes

This study concerns the characteristics of the partially averaged Navier–Stokes method for local flow analysis around a rotating propeller. Partially averaged Navier–Stokes, resolving crucial large-scale structures of turbulent flow at a given computational grid resolution, is a bridging turbulence closure model between the Reynolds-averaged Navier–Stokes equation and the direct numerical simulation. A detailed comparison between partially averaged Navier–Stokes and Reynolds-averaged Navier–Stokes models is made to achieve a better understanding of partially averaged Navier–Stokes characteristics for predicting the coherent structures in turbulent flow. The two-equation k-ω shear stress transport model and the seven-equation Reynolds stress model are selected for Reynolds-averaged Navier–Stokes computations. The problem of interest is the flow around a rotating KP505 propeller in open water conditions at an advance ratio of 0.7. Near the leading edge, the partially averaged Navier–Stokes results are similar to those of Reynolds stress model in terms of the vortical structures. Vorticity predicted by different turbulence models, however, shows significant differences. For a more detailed analysis, the velocity gradient constituting the vorticity is identified at the leading edge. It is proven that partially averaged Navier–Stokes is able to capture the anisotropic characteristics of the flow at the leading edge, where both the geometric and flow characteristics change abruptly.

Hemoglobin crystals of the red blood cells in the human renal cortex: electron microscopic observations of the renal lithiasis

1978 ◽  
Vol 36 (2) ◽  
pp. 480-481
Author(s):  
Kosuke Ueda ◽  
Hiroto Washida ◽  
Nakazo Watari
Keyword(s):  
Red Blood Cells ◽  
Blood Cells ◽  
Renal Cortex ◽  
Uranyl Acetate ◽  
Osmic Acid ◽  
Renal Lithiasis ◽  
Electron Microscopic ◽  
Hemoglobin C ◽  
First Case ◽  
Ultrathin Sections

IntroductionHemoglobin crystals in the red blood cells were electronmicroscopically reported by Fawcett in the cat myocardium. In the human, Lessin revealed crystal-containing cells in the periphral blood of hemoglobin C disease patients. We found the hemoglobin crystals and its agglutination in the erythrocytes in the renal cortex of the human renal lithiasis, and these patients had no hematological abnormalities or other diseases out of the renal lithiasis. Hemoglobin crystals in the human erythrocytes were confirmed to be the first case in the kidney.Material and MethodsTen cases of the human renal biopsies were performed on the operations of the seven pyelolithotomies and three ureterolithotomies. The each specimens were primarily fixed in cacodylate buffered 3. 0% glutaraldehyde and post fixed in osmic acid, dehydrated in graded concentrations of ethanol, and then embedded in Epon 812. Ultrathin sections, cut on LKB microtome, were doubly stained with uranyl acetate and lead citrate.

Densitometric Identification of Primitive Erythroblasts After Reaction With Diaminobenzidine

1973 ◽  
Vol 31 ◽  
pp. 328-329
Author(s):  
John A. Trotter
Keyword(s):  
Red Blood Cells ◽  
Analytical Method ◽  
Blood Cells ◽  
Guinea Pigs ◽  
Specific Protein ◽  
Visual Examination ◽  
Hemoglobin Synthesis ◽  
Peroxidatic Activity ◽  
Small Density

Hemoglobin is the specific protein of red blood cells. Those cells in which hemoglobin synthesis is initiated are the earliest cells that can presently be considered to be committed to erythropoiesis. In order to identify such early cells electron microscopically, we have made use of the peroxidatic activity of hemoglobin by reacting the marrow of erythropoietically stimulated guinea pigs with diaminobenzidine (DAB). The reaction product appeared as a diffuse and amorphous electron opacity throughout the cytoplasm of reactive cells. The detection of small density increases of such a diffuse nature required an analytical method more sensitive and reliable than the visual examination of micrographs. A procedure was therefore devised for the evaluation of micrographs (negatives) with a densitometer (Weston Photographic Analyzer).

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