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Nature of Flow of a Liquid
Published in Wilmer W Nichols, Michael F O'Rourke, Elazer R Edelman, Charalambos Vlachopoulos, McDonald's Blood Flow in Arteries, 2022
A suitable system for the measurement of blood or plasma viscosity must have several features for clinical applications. These include rapid, reproducible and precise measurements, small blood or plasma sample volume, simulated in vivo time-varying flow conditions using oscillatory flow in a tube, precise thermal control, simple operation, and minimal exposure of operator to blood-borne pathogens. The porous bed viscometer is a convenient means to measure whole blood viscosity in humans, and it should be useful as a screening test for clinical and epidemiologic studies (Crowley et al., 1991). In a later study, Crowley et al. (1994) found strong positive correlations between blood viscosity and packed cell volume, total cholesterol, triglycerides and low-density lipoprotein cholesterol and a negative correlation between blood viscosity and high-density lipoprotein cholesterol.
Disorders in tHemostasis System and Changes in the Rheological Properties of the Blood in Ischemic Heart Disease and Diabetes Mellitus Patients
Published in E.I. Sokolov, Obesity and Diabetes Mellitus, 2020
Currently, biophysics has no clear scheme of parameters that could characterize the rheological properties of blood and erythrocyte suspensions. The most acceptable is the Kesson model on whose basis the rheological parameters of the blood are characterized by the following parameters: (i) the yield point; (ii) the Kesson viscosity, and (iii) the apparent viscosity (the viscosity of the blood determined with a viscometer) at a shear rate of 1 s−1.
Plasma and Blood Viscosity
Published in Gordon D. O. Lowe, Clinical Blood Rheology, 2019
Three types of rotational viscometer have been used for clinical blood viscosity measurement: cone-plate, cone-in-cone, and coaxial cylinder (Couette) instruments. Their design features have been considered elsewhere.16,17,78,79
Machine learning prediction of antibody aggregation and viscosity for high concentration formulation development of protein therapeutics
Published in mAbs, 2022
Pin-Kuang Lai, Austin Gallegos, Neil Mody, Hasige A. Sathish, Bernhardt L. Trout
One of the major challenges in applying machine learning to predict antibody stability at high concentration is developing robust models with a limited amount of data. In previous work, our group has trained a viscosity classification model using 27 commercial mAbs.9 In this study, the viscosity of 20 preclinical and clinical stage mAbs were measured in a similar solution condition as that of the previous work (histidine/histidine-HCl buffer at pH 6.0, without surfactant and other excipients). A Chinese hamster ovary expression system used to produce the material and, following purification, the starting monomer purity was >95%. In both studies, the viscosity was measured at 18–20°C by VROC Initium viscometer at multiple shear rates. For the 27 commercial mAbs, non-Newtonian effects were assumed. In this study, we found non-Newtonian effects for low viscosity mAbs were negligible, but significant for high viscosity mAbs. For high viscosity mAbs, viscosity was extrapolated to zero-shear rate.
Mucoadhesive thermoreversible formulation of metoclopramide for rectal administration: a promising strategy for potential management of chemotherapy-induced nausea and vomiting
Published in Pharmaceutical Development and Technology, 2020
Mahmoud M. El-Sonbaty, Hatem R. Ismail, Alaa A. Kassem, Ahmed M. Samy, Mohamed A. Akl
The rheological parameters of the selected MCP HCl-LS formulations were estimated using cone/plate Wells viscometer (Brookfield®, HBDV-II + PROCP, 230 V, 50/60 Hz, Brookfield Engineering Laboratories, INC., USA), (Tung, 1994; Ban and Kim 2013). Sample (0.5 mL) was placed on the lower plate of the viscometer ensuring that formulation shearing was minimized, and permitted to be stabilized for at least 5 min before testing. The measurements were performed at 25 °C (RT) and 37 °C (rectal temperature) utilizing spindle 52 at a range of 5–400 rpm shear rate (SR). From the readings of the viscometer, the rheological parameters including share rate (SR) in s−1, shear stress (SS) in dyne/cm2 and the viscosity, ή in millipascal-second (MPa.S) were estimated, and fitted to the equation below for obtaining the flow index (n) and consistency index (m) characteristic for each formula.
Formulation, characterization, and in vitro/ex vivo evaluation of quercetin-loaded microemulsion for topical application
Published in Pharmaceutical Development and Technology, 2018
Azar Kajbafvala, Alireza Salabat, Anayatollah Salimi
Viscosities were measured using a rotational type programmable viscometer (LV DV-II + Brookfield, Inc., Middleboro, MA) at 25 °C and spindle no. 34. Rheogram curves were plotted with rotation speeds 0–200 rpm to show the rheological behavior of the microemulsion formulations. The viscometer drives the spindle immersed into the sample holder containing the test fluid sample. Temperature of the test sample is monitored by a temperature sensor embedded into the sample holder. The viscometer is connected to a computer which records the data automatically. The data collection is done by software (Wingather, Brookfield, Inc., Middleboro, MA), which collects spindle RPM, torque, viscosity, shear stress, shear rate, temperature, and time. The viscometer has a specified accuracy of ±1%.