Kinetics of rouleaux formation using TV image analyzer. I. Human erythrocytes

1983 ◽  
Vol 245 (2) ◽  
pp. H252-H258 ◽  
Author(s):  
T. Shiga ◽  
K. Imaizumi ◽  
N. Harada ◽  
M. Sekiya
Keyword(s):  
Ph Effect ◽  
Three Dimensional ◽  
Image Analyzer ◽  
Autologous Plasma ◽  
Human Fibrinogen ◽  
Shear Rates ◽  
Lower Shear ◽  
Time Courses ◽  
The Individual ◽  
Rouleaux Formation

An apparatus for determining the velocity of erythrocyte rouleaux formation was constructed, combining an inverted microscope, a transparent cone-plate viscometer, a TV image analyzer, and a computer. At lower shear rates, the overall process is the sedimentation and the rouleaux formation followed by the development of three-dimensional aggregates. The individual erythrocyte could be observed and the process was expressed by the time courses of the changes in the count and area of particles; taking the computed increment in the area/count, the rate of rouleaux formation could be estimated. The effects of shear rates, hematocrits, plasma proteins, and pH were quantified. The rate of rouleaux formation in autologous plasma increased by (1) lowering the shear rates (1.9 less than or equal to gamma less than or equal to 15 s-1),2) increasing the hematocrit (up to 0.6%), 3) adding human fibrinogen (up to 600 mg/dl) or gamma-globulin, and 4) increasing pH. The transformation to echinocytes or to stomatocytes decreased the rate of rouleaux formation. The pH effect was explained by the increase in mean corpuscular volume at lower pH rather than by the changes in the electrostatic repulsion or in the protein binding.

Kinetics of rouleaux formation using TV image analyzer. II. Rat erythrocytes

1983 ◽  
Vol 245 (2) ◽  
pp. H259-H264 ◽  
Author(s):  
T. Shiga ◽  
K. Imaizumi ◽  
N. Maeda ◽  
K. Kon
Keyword(s):  
Kinetic Model ◽  
Rate Constant ◽  
Three Dimensional ◽  
Erythrocyte Aggregation ◽  
Image Analyzer ◽  
One Dimensional ◽  
Specific Pathogen ◽  
Time Courses ◽  
Kinetics Of ◽  
Rouleaux Formation

With the use of a rheoscope combined with a TV image analyzer, the kinetics of specific pathogen-free rat erythrocyte aggregation was studied. Under certain conditions (gamma 7.5 s-1, hematocrit 0.36%, in own plasma, at 25 degrees C) one-dimensional aggregates (rouleaux) were formed without the development of three-dimensional aggregates, perhaps because of very low concentration of gamma-globulin. The observed phenomena could be explained by 1) the erythrocyte sedimentation and 2) the rouleaux formation. The time courses, of the biphasic change in erythrocyte count and of the increments in total area and in the area/count, were successfully simulated by a kinetic model of linear polymerization, assuming a sedimentation rate constant and an association rate constant. Further, a Poissonlike distribution of the length of rouleaux was shown, as predicted theoretically on the basis of the same kinetic model.

SHEARING EFFECTS ON THE ELECTRORHEOLOGICAL RESPONSE

2001 ◽  
Vol 15 (06n07) ◽  
pp. 930-937 ◽  
Author(s):  
K. TANAKA ◽  
S. HASHIMOTO ◽  
T. TAKENOUCHI ◽  
I. SUGIMOTO ◽  
A. KUBONO ◽  
...  
Keyword(s):  
Shear Rate ◽  
Electric Field ◽  
Transient Response ◽  
Stress Responses ◽  
Experimental Conditions ◽  
Transient Stress ◽  
Shear Rates ◽  
Lower Shear ◽  
Mason Number ◽  
The Individual

The steady and transient stress responses were investigated from lower shear rates to higher shear rates at a given strength of the electric field, and the individual experimental conditions were reduced to Mason number ( M n). The electro-rheological response was found in the region with higher M n of the order of 10, and the transient response became faster as the shear rate increased. These results show that the effect of chance of collision among the polarized particles would play an important role even in the region.

scholarly journals Distal Placement of an End-to-Side Bypass Graft Anastomosis: A 3-D Computational Study

2005 ◽  
Author(s):  
John R. DiCicco ◽  
Ayodeji O. Demuren
Keyword(s):  
Stokes Equations ◽  
Computational Study ◽  
Bypass Graft ◽  
Three Dimensional ◽  
Rate Equations ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Shear Rates ◽  
Lower Shear ◽  
Hexahedral Elements

A three-dimensional (3-D) computational fluid dynamics study of shear rates around distal end-to-side anastomoses has been conducted. Three 51% and three 75% cross-sectional area reduced 6 mm cylinders were modeled each with a bypass cylinder attached at a 30 degree angle at different placements distal to the constriction. Steady, incompressible, Newtonian blood flow was assumed, and the full Reynolds-averaged Navier-Stokes equations and turbulent kinetic energy and specific dissipation rate equations were solved on a locally structured multi-block mesh with hexahedral elements. Consequently, distal placement of an end-to-side bypass graft anastomosis was found to have an influence on the shear rate magnitudes. For the 75% constriction, closer placements produced lower shear rates near the anastomosis. Hence, there is potential for new plaque formation and graft failure.

scholarly journals Distal Placement of an End-to-Side Bypass Graft Anastomosis: A 3D Computational Study

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
John Di Cicco ◽  
Ayodeji Demuren
Keyword(s):  
Stokes Equations ◽  
Computational Study ◽  
Bypass Graft ◽  
Three Dimensional ◽  
Rate Equations ◽  
Navier Stokes ◽  
Cross Sectional ◽  
Shear Rates ◽  
Lower Shear ◽  
Hexahedral Elements

A three-dimensional (3D) computational fluid dynamics study of shear rates around distal end-to-side anastomoses has been conducted. Three 51% and three 75% cross-sectional area-reduced 6 mm cylinders were modeled each with a bypass cylinder attached at a 30-degree angle at different placements distal to the constriction. Steady, incompressible, Newtonian blood flow was assumed, and the full Reynolds-averaged Navier-Stokes equations, turbulent kinetic energy, and specific dissipation rate equations were solved on a locally structured multiblock mesh with hexahedral elements. Consequently, distal placement of an end-to-side bypass graft anastomosis was found to have an influence on the shear rate magnitudes. For the 75% constriction, closer placements produced lower shear rates near the anastomosis. Hence, there is potential for new plaque formation and graft failure.

Semi-automated methods for 3-D reconstruction of macromolecular complexes

1995 ◽  
Vol 53 ◽  
pp. 42-43
Author(s):  
B. Carragher ◽  
M. Whittaker
Keyword(s):  
Three Dimensional ◽  
Time Saving ◽  
Macromolecular Complexes ◽  
Symmetry Properties ◽  
Dimensional Reconstruction ◽  
Experienced Operator ◽  
Projection Images ◽  
The Individual ◽  
Natural Symmetry

Techniques for three-dimensional reconstruction of macromolecular complexes from electron micrographs have been successfully used for many years. These include methods which take advantage of the natural symmetry properties of the structure (for example helical or icosahedral) as well as those that use single axis or other tilting geometries to reconstruct from a set of projection images. These techniques have traditionally relied on a very experienced operator to manually perform the often numerous and time consuming steps required to obtain the final reconstruction. While the guidance and oversight of an experienced and critical operator will always be an essential component of these techniques, recent advances in computer technology, microprocessor controlled microscopes and the availability of high quality CCD cameras have provided the means to automate many of the individual steps.During the acquisition of data automation provides benefits not only in terms of convenience and time saving but also in circumstances where manual procedures limit the quality of the final reconstruction.

Adenosine Diphosphate-Induced Aggregation of Human Platelets in Flow Through Tubes: III. Shear and Extrinsic Fibrinogen-Dependent Effects

1994 ◽  
Vol 71 (01) ◽  
pp. 078-090 ◽  
Author(s):  
H L Goldsmith ◽  
M M Frojmovic ◽  
Susan Braovac ◽  
Fiona McIntosh ◽  
T Wong
Keyword(s):  
Shear Rate ◽  
Single Cells ◽  
Adenosine Diphosphate ◽  
Human Platelets ◽  
Size Analysis ◽  
Fibrinogen Concentration ◽  
Human Fibrinogen ◽  
Shear Rates ◽  
Rate Dependent ◽  
Induced Aggregation

SummaryThe effect of shear rate and fibrinogen concentration on adenosine diphosphate-induced aggregation of suspensions of washed human platelets in Poiseuille flow at 23°C was studied using a previously described double infusion technique and resistive particle counter size analysis (1). Using suspensions of multiple-centrifuged and -washed cells in Tyrodes-albumin [3 × 105 μl−1; (17)] with [fibrinogen] from 0 to 1.2μM, the, rate and extent of aggregation with 0.7 μM ADP in Tyrodes-albumin were measured over a range of mean transit times from 0.2 to 43 s, and at mean tube shear rates, Ḡ, = 41.9, 335 and 1,335 s−1. As measured by the decrease in singlet concentration, aggregation at 1.2 μM fibrinogen increased with increasing Ḡ up to 1,335 s1, in contrast to that previously reported in citratcd plasma, in which aggregation reached a maximum at Ḡ = 335 s−1. Without added fibrinogen, there was no aggregation at Ḡ = 41.9 s1; at Ḡ = 335 s1, there was significant aggregation but with an initial lag time, aggregation increasing further at Ḡ = 1,335 s−1. Without added fibrinogen, aggregation was abolished at all Ḡ upon incubation with the hexapeptide GRGDSP, but was almost unaffected by addition of an F(ab’)2 fragment of an antibody to human fibrinogen. Aggregation in the absence of added fibrinogen was also observed at 37°C. The activation of the multiple-washed platelets was tested using flow cytometry with the fluorescently labelled monoclonal antibodies FITC-PAC1 and FITC-9F9. It was shown that 57% of single cells in unactivated PRT expressed maximal GPIIb-IIIa fibrinogen receptors (MoAb PAC1) and 54% expressed pre-bound fibrinogen (MoAb 9F9), with further increases on ADP activation. However, incubation with GRGDSP and the F(ab’)2 fragment did not inhibit the prebound fibrinogen. Moreover, relatively unactivated cells (8% expressing receptor, 14% prebound fibrinogen), prepared from acidified cPRP by single centrifugation with 50 nM of the stable prostacyclin derivative, ZK 36 374, and resuspension in Tyrodes-albumin at 5 × 104 μl−1, aggregated with 2 and 5 μM ADP at Ḡ = 335 and 1,335 s−1 in the absence of added fibrinogen. We therefore postulate that a protein such as von Willebrand factor, secreted during platelet isolation or in flow at sufficiently high shear rates, may yield the observed shear-rate dependent aggregation without fibrinogen.

Phonetic iconicity in the evaluative morphology of a sample of Indo-European, Niger-Congo and Austronesian languages

2010 ◽  
Vol 3 (2) ◽  
pp. 156-180 ◽  
Author(s):  
Renáta Gregová ◽  
Lívia Körtvélyessy ◽  
Július Zimmermann
Keyword(s):  
Three Dimensional ◽  
Sound Symbolism ◽  
Three Dimensional Model ◽  
Austronesian Languages ◽  
Place Of Articulation ◽  
European Languages ◽  
Phonetic Symbolism ◽  
The Individual ◽  
Core Vocabulary

Universals Archive (Universal #1926) indicates a universal tendency for sound symbolism in reference to the expression of diminutives and augmentatives. The research ( Štekauer et al. 2009 ) carried out on European languages has not proved the tendency at all. Therefore, our research was extended to cover three language families – Indo-European, Niger-Congo and Austronesian. A three-step analysis examining different aspects of phonetic symbolism was carried out on a core vocabulary of 35 lexical items. A research sample was selected out of 60 languages. The evaluative markers were analyzed according to both phonetic classification of vowels and consonants and Ultan's and Niewenhuis' conclusions on the dominance of palatal and post-alveolar consonants in diminutive markers. Finally, the data obtained in our sample languages was evaluated by means of a three-dimensional model illustrating the place of articulation of the individual segments.

Formation and Destruction of Platelet Aggregates in Viscometric Flow

1975 ◽  
Author(s):  
H. Rieger ◽  
H. Schmid-Schönbein
Keyword(s):  
Initial Rate ◽  
Aggregate Stability ◽  
Creeping Flow ◽  
Experimental Conditions ◽  
Shear Rates ◽  
Independent Variables ◽  
Lower Shear ◽  
Platelet Aggregates ◽  
Blood Elements ◽  
Shape Changes

Even after pseudopodia formation platelets - unlike all other known formed blood elements - remain dispersed in stasis and creeping flow and become aggregated only in the presence of a minimum amount of shearing. The “rheoaggregometer” (Rieger et al., Pflüger’s Archiv, 343, R 33, 1973) allows to measure the minimum shear rates necessary for platelet aggregation (PA), as well as the initial rate and the maximum extent of PA in citrated PRP.PA is quantified photometrically as a function of variable shear rates. The initial rate of PA steadily increases with increasing shear rates up to 460 sec-1. However, the maximal extent of PA (indicating the mechanical integrity of formed aggregates) saturates at about 35 sec-1 and then decreases because of a destruction of formed aggregates and of prevention of further PA. The aggregability of the platelets, as reflected by various degrees of shape changes, is enhanced by a drop of temperature and a rise in pH as well as by the so called aggregating agents (e.g. epinephrine 10-6 up to 10-9 M/l) : consecutively lower shear rates (lower effects of collision) are necessary to induce PA. In citrated PRP stable platelet aggregates are produced only within a defined range of shear rates. Platelet aggregability and aggregate stability are independent variables influenced by different experimental conditions.

scholarly journals Modelling Polycrystalline Materials: An Overview of Three-Dimensional Grain-Scale Mechanical Models

2013 ◽  
Vol 05 (01) ◽  
pp. 1350002 ◽  
Author(s):  
I. Benedetti ◽  
F. Barbe
Keyword(s):  
Three Dimensional ◽  
Constitutive Modelling ◽  
Polycrystalline Materials ◽  
High Fidelity ◽  
Computational Capability ◽  
Mechanical Models ◽  
Three Dimensional Models ◽  
The Individual ◽  
Individual Grains ◽  
Micro Structures

A survey of recent contributions on three-dimensional grain-scale mechanical modelling of polycrystalline materials is given in this work. The analysis of material micro-structures requires the generation of reliable micro-morphologies and affordable computational meshes as well as the description of the mechanical behavior of the elementary constituents and their interactions. The polycrystalline microstructure is characterized by the topology, morphology and crystallographic orientations of the individual grains and by the grain interfaces and microstructural defects, within the bulk grains and at the inter-granular interfaces. Their analysis has been until recently restricted to two-dimensional cases, due to high computational requirements. In the last decade, however, the wider affordability of increased computational capability has promoted the development of fully three-dimensional models. In this work, different aspects involved in the grain-scale analysis of polycrystalline materials are considered. Different techniques for generating artificial micro-structures, ranging from highly idealized to experimentally based high-fidelity representations, are briefly reviewed. Structured and unstructured meshes are discussed. The main strategies for constitutive modelling of individual bulk grains and inter-granular interfaces are introduced. Some attention has also been devoted to three-dimensional multiscale approaches and some established and emerging applications have been discussed.

Research on Generation Rules of Chest Width Point Curve Based on 3D Female Mannequin

2013 ◽  
Vol 796 ◽  
pp. 513-518
Author(s):  
Rong Jin ◽  
Bing Fei Gu ◽  
Guo Lian Liu
Keyword(s):  
Point Cloud ◽  
Three Dimensional ◽  
Upper Body ◽  
Secondary Development ◽  
Linear Regression Method ◽  
Point Cloud Data ◽  
Body Type ◽  
Cloud Data ◽  
Engineering Software ◽  
The Individual

In this paper 110 female undergraduates in Soochow University are measured by using 3D non-contact measurement system and manual measurement. 3D point cloud data of human body is taken as research objects by using anti-engineering software, and secondary development of point cloud data is done on the basis of optimizing point cloud data. In accordance with the definition of the human chest width points and other feature points, and in the operability of the three-dimensional point cloud data, the width, thickness, and length dimensions of the curve through the chest width point are measured. Classification of body type is done by choosing the ratio values as classification index which is the ratio between thickness and width of the curve. The generation rules of the chest curve are determined for each type by using linear regression method. Human arm model could be established by the computer automatically. Thereby the individual model of the female upper body mannequin modeling can be improved effectively.

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