ISSN / EISSN : 0006-355X / 1878-5034
Published by: IOS Press (10.3233)
Total articles ≅ 2,375
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Biorheology, Volume 58, pp 93-95; https://doi.org/10.3233/bir-219904
Biorheology, Volume 58, pp 173-189; https://doi.org/10.3233/bir-219906
Biorheology, Volume 58, pp 107-171; https://doi.org/10.3233/bir-219905
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Biorheology, Volume 58, pp 61-61; https://doi.org/10.3233/bir-219900
Biorheology, Volume 58, pp 97-99; https://doi.org/10.3233/bir-219902
Biorheology, pp 1-9; https://doi.org/10.3233/bir-210014
BACKGROUND: Saliva is a complex fluid that lubricates the oropharynx and facilitates chewing, swallowing, and vocalization. Viscoelasticity is critical for the ability of saliva to fulfill these functions. Xerostomia, or a sensation of dry mouth, occurs in 17–26% of the population. Although many equate xerostomia with hyposalivation, high-risk patients frequently report oral dryness in the absence of decreased salivary flow. OBJECTIVE: This study aims to determine if xerostomia is associated with alterations in the rheological properties of saliva in addition to decreased salivary production. METHODS: The study population included patients with post-radiation xerostomia, patients with anticholinergic-induced xerostomia and healthy controls. Salivary volumetric flow rate was measured, shear viscosity was measured using oscillatory rheometry, and extensional viscosity was measured using capillary thinning methods. Groups were compared using descriptive statistics and univariate analysis. RESULTS: A total of 36 subjects were included: 15 with post-radiation xerostomia, 9 with anticholinergic-induced xerostomia and 12 controls. Salivary volumetric flow was significantly decreased in post-radiation and anticholinergic-induced patients compared to controls. On capillary thinning testing, saliva from xerostomia patients had significantly greater extensional viscosity compared to controls. However, saliva from the three groups showed no significant difference in the complex viscosity or the storage or loss modulus of saliva with oscillatory rheology. CONCLUSIONS: Xerostomia is associated with decreased salivary volumetric flow and quantitative changes in the rheologic properties of saliva.
Biorheology, pp 1-18; https://doi.org/10.3233/bir-201019
BACKGROUND: Computational fluid dynamics (CFD) is an important tool for predicting cardiovascular device performance. The FDA developed a benchmark nozzle model in which experimental and CFD data were compared, however, the studies were limited by steady flows and Newtonian models. OBJECTIVE: Newtonian and non-Newtonian blood models will be compared under steady and pulsatile flows to evaluate their influence on hemodynamics in the FDA nozzle. METHODS: CFD simulations were validated against the FDA data for steady flow with a Newtonian model. Further simulations were performed using Newtonian and non-Newtonian models under both steady and pulsatile flows. RESULTS: CFD results were within the experimental standard deviations at nearly all locations and Reynolds numbers. The model differences were most evident at Re = 500, in the recirculation regions, and during diastole. The non-Newtonian model predicted blunter upstream velocity profiles, higher velocities in the throat, and differences in the recirculation flow patterns. The non-Newtonian model also predicted a greater pressure drop at Re = 500 with minimal differences observed at higher Reynolds numbers. CONCLUSIONS: An improved modeling framework and validation procedure were used to further investigate hemodynamics in geometries relevant to cardiovascular devices and found that accounting for blood’s non-Newtonian and pulsatile behavior can lead to large differences in predictions in hemodynamic parameters.