Comparison of low-shear and high-shear granulation processes: effect on implantable calcium phosphate granule properties

Aim: We aimed to assess the association of whole blood with thromboembolic milieu in significant mitral stenosis patients. Methodology & results: We included 122 patients and classified patients into two groups as having thrombogenic milieu, thrombogenic milieu (+), otherwise patients without thrombogenic milieu, thrombogenic milieu (-). Whole blood viscosity (WBV) in both shear rates were higher in thrombogenic milieu (+) group comparing with thrombogenic milieu (-). WBV at high shear rate and WBV at low shear rate parameters were moderately correlated with grade of spontaneous echo contrast. Adjusted with other parameters, WBV parameters at both shear rates were associated with presence of thrombogenic milieu. Discussion & conclusion: We found that extrapolated WBV at both shear rates was significantly associated with the thrombogenic milieu in mitral stenosis. This easily available parameter may provide additional perspective about thrombogenic diathesis.

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Rheology of Fluoride Gels

Journal of Dental Research ◽

10.1177/00220345760550031001 ◽

1976 ◽

Vol 55 (3) ◽

pp. 353-356 ◽

Cited By ~ 6

Author(s):

M. Braden ◽

Ratna Perera

Keyword(s):

Infrared Spectroscopy ◽

Shear Rate ◽

Elastic Behavior ◽

Shear Stresses ◽

High Shear ◽

Shear Rates ◽

Extreme Stress ◽

Thickening Agents ◽

Shear Rate Dependence ◽

Low Shear

Six commercial fluoride gels have been studied, using a cone and plate viscometer. Also, the thickening agents have been analyzed using infrared spectroscopy. All gels showed stress thinning, which is the decrease of viscosity with shear rate. Such shear rate dependence is clinically convenient in that the gel will flow readily at the high shear stresses present when the gel is applied but will not flow readily under its own weight when on the tooth. Five materials containing hydroxyalkyl celluloses showed similar degrees of shear thinning. One material with a non-cellulosic thickener showed much more extreme stress thinning together with elastic behavior at low shear rates; such behavior may be clinically advantageous. All of the gels showed only slight temperature dependence of rheological properties.

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Microfiltration performance: physicochemical aspects of whey pretreatment

Journal of Dairy Research ◽

10.1017/s0022029900030971 ◽

1995 ◽

Vol 62 (2) ◽

pp. 269-279 ◽

Cited By ~ 15

Author(s):

Genevieve Gesan ◽

Georges Daufin ◽

Uzi Merin ◽

Jean-Pierre Labbe ◽

Auguste Quemerais

Keyword(s):

Calcium Phosphate ◽

Membrane Surface ◽

Physicochemical Process ◽

High Shear ◽

Lower Content ◽

Phosphate Ions ◽

Complex Lipid ◽

Ionic Calcium ◽

Calcium Phosphate Particles ◽

Soluble Calcium

SUMMARYClarification of whey by microfiltration (MF) can be achieved after appropriate pretreatment of the feed. A control pretreatment consists of a physicochemical process comprising increased ionic calcium and pH accompanied by heat (50 °C, 15 min) to cause aggregation of complex lipid–calcium phosphate particles, which are then separated by MF. This pretreatment process was modified by increasing the temperature to 55 °C and by maintaining the pH constant during heat treatment. This modification resulted in larger calcium phosphate particles and a lower content of soluble calcium and phosphate ions. As a consequence, a longer period of MF operation, better whey clarification and lower calcium and phosphate content of the filtrate were achieved. This suggests that a loosely structured deposit was formed on the membrane surface which was less resistant to filtration than that resulting from the control pretreatment. During MF, it was necessary to avoid zones of high shear in the retentate compartment that might cause physical alteration of the aggregates.

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The Simulation of Aggregated Colloids Under Flow

MRS Proceedings ◽

10.1557/proc-289-33 ◽

1992 ◽

Vol 289 ◽

Author(s):

John R. Melrose

Keyword(s):

Shear Rate ◽

Large Scale ◽

Shear Thinning ◽

High Shear ◽

Shear Rates ◽

Rouse Model ◽

High Shear Rates ◽

Structural Breakdown ◽

Large Scale Simulations ◽

Low Shear

AbstractAn overview is given of theories of aggregates under flow. These generally assume some sort of structural breakdown as the shear rate is increased. Models vary with both the rigidity of the bonding and the level of treatment of hydrodynamics. Results are presented for simulations of a Rouse model of non-rigid, (i.e. central force) weakly bonded aggregates. In large scale simulations different structures are observed at low and high shear rates. The change from one structure to another is associated with a change in the rate of shear thinning. The model captures low shear rate features of real systems absent in previous models: this feature is ascribed to agglomerate deformations. Quantitatively, the model is two orders of magnitude out from experiment but some scaling is possible.

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High glucose induced NF-κB DNA-binding activity in HAEC is maintained under low shear stress but inhibited under high shear stress: role of nitric oxide

Atherosclerosis ◽

10.1016/j.atherosclerosis.2003.08.023 ◽

2003 ◽

Vol 171 (2) ◽

pp. 225-234 ◽

Cited By ~ 17

Author(s):

S Mohan

Keyword(s):

Nitric Oxide ◽

Shear Stress ◽

High Glucose ◽

Binding Activity ◽

High Shear ◽

High Shear Stress ◽

Dna Binding Activity ◽

Low Shear Stress ◽

Low Shear

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Integrin VLA-4 enhances sialyl-Lewisx/a-negative melanoma adhesion to and extravasation through the endothelium under low flow conditions

AJP Cell Physiology ◽

10.1152/ajpcell.00245.2008 ◽

2008 ◽

Vol 295 (3) ◽

pp. C701-C707 ◽

Cited By ~ 39

Author(s):

Shile Liang ◽

Cheng Dong

Keyword(s):

Endothelial Cells ◽

Shear Flow ◽

Tumor Cells ◽

Melanoma Cell ◽

Melanoma Cells ◽

Host Cells ◽

High Shear ◽

Sialyl Lewis ◽

Adhesive Interactions ◽

Low Shear

During their passage through the circulatory system, tumor cells undergo extensive interactions with various host cells including endothelial cells. The capacity of tumor cells to form metastasis is related to their ability to interact with and extravasate through endothelial cell layers, which involves multiple adhesive interactions between tumor cells and endothelium (EC). Thus it is essential to identify the adhesive receptors on the endothelial and melanoma surface that mediate those specific adhesive interactions. P-selectin and E-selectin have been reported as adhesion molecules that mediate the cell-cell interaction of endothelial cells and melanoma cells. However, not all melanoma cells express ligands for selectins. In this study, we elucidated the molecular constituents involved in the endothelial adhesion and extravasation of sialyl-Lewisx/a-negative melanoma cell lines under flow in the presence and absence of polymorphonuclear neutrophils (PMNs). Results show the interactions of α4β1(VLA-4) on sialyl-Lewisx/a-negative melanoma cells and vascular adhesion molecule (VCAM-1) on inflamed EC supported melanoma adhesion to and subsequent extravasation through the EC in low shear flow. These findings provide clear evidence for a direct role of the VLA-4/VCAM-1 pathway in melanoma cell adhesion to and extravasation through the vascular endothelium in a shear flow. PMNs facilitated melanoma cell extravasation under both low and high shear conditions via the involvement of distinct molecular mechanisms. In the low shear regime, β2-integrins were sufficient to enhance melanoma cell extravasation, whereas in the high shear regime, selectin ligands and β2-integrins on PMNs were necessary for facilitating the melanoma extravasation process.

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Thrombus Initiation With Subsequent Growth Measured for Physiological Shear and High Pathological Shear

ASME 2011 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2011-53865 ◽

2011 ◽

Author(s):

David L. Bark ◽

Andrea N. Para ◽

David N. Ku

Keyword(s):

Myocardial Infarction ◽

Acute Myocardial Infarction ◽

Heart Attack ◽

Arterial Thrombosis ◽

Atherosclerotic Disease ◽

High Shear ◽

Subsequent Growth ◽

Low Shear ◽

Undisturbed Flow

Arterial thrombosis is often found near an atheroma in atherosclerotic disease, which can lead to acute myocardial infarction, i.e. a heart attack. Thrombus typically grows in regions of exposed subendothelium, which can exist when the plaque cap of the atheroma ruptures or erodes. The subendothelium creates an adherent surface to platelets and other thrombus constituents. Furthermore, an atheroma alters the normal physiological hemodynamics, which has been reported to correspond to local thrombus growth, despite equally adherent surfaces in undisturbed flow regions [1,2]. However, there has been some disagreement about which hemodynamics, specifically shear, may play the most influential role of localizing thrombus. Low shear and high shear have both resulted in thrombus growth [1,2]. Shear in the region of an atheroma can get over 100,000 s−1 [3].

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Characterization of the Metabolic Response of Streptomyces clavuligerus to Shear Stress in Stirred Tanks and Single-Use 2D Rocking Motion Bioreactors for Clavulanic Acid Production

Antibiotics ◽

10.3390/antibiotics8040168 ◽

2019 ◽

Vol 8 (4) ◽

pp. 168 ◽

Cited By ~ 5

Author(s):

David Gómez-Ríos ◽

Stefan Junne ◽

Peter Neubauer ◽

Silvia Ochoa ◽

Rigoberto Ríos-Estepa ◽

...

Keyword(s):

Shear Stress ◽

Clavulanic Acid ◽

Metabolic Response ◽

Streptomyces Clavuligerus ◽

High Shear ◽

Shear Forces ◽

Rocking Motion ◽

Single Use ◽

The Impact ◽

Low Shear

Streptomyces clavuligerus is a gram-positive filamentous bacterium notable for producing clavulanic acid (CA), an inhibitor of β-lactamase enzymes, which confers resistance to bacteria against several antibiotics. Here we present a comparative analysis of the morphological and metabolic response of S. clavuligerus linked to the CA production under low and high shear stress conditions in a 2D rocking-motion single-use bioreactor (CELL-tainer ®) and stirred tank bioreactor (STR), respectively. The CELL-tainer® guarantees high turbulence and enhanced volumetric mass transfer at low shear stress, which (in contrast to bubble columns) allows the investigation of the impact of shear stress without oxygen limitation. The results indicate that high shear forces do not compromise the viability of S. clavuligerus cells; even higher specific growth rate, biomass, and specific CA production rate were observed in the STR. Under low shear forces in the CELL-tainer® the mycelial diameter increased considerably (average diameter 2.27 in CELL-tainer® vs. 1.44 µm in STR). This suggests that CA production may be affected by a lower surface-to-volume ratio which would lead to lower diffusion and transport of nutrients, oxygen, and product. The present study shows that there is a strong correlation between macromorphology and CA production, which should be an important aspect to consider in industrial production of CA.

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