Amyloid fibrill formation in microgravity: Distinguishing interfacial flow effects

Project: Research project

Description

The PI Lopez and the GRA will be primarily responsible for the theoretical modeling and numerical simulations of both the ground-based and space-based experiments. There will be close co-ordination between the ASU and the RPI groups, primarily via weekly group conference calls using skype. The initial tasks are the determination of the interfacial and bulk hydrodynamic properties of protein solutions at various concentrations. This involves both experiments in the deep-channel surface viscometer to measure interfacial velocity profiles which will then be compared with numerical profiles in order to back out surface shear viscosity over a wide range of shear rates. This requires computing the Navier-Stokes equations coupled to the interfacial stress balance; Lopez and GRA will be responsible for these. These comparisons between theory and experiments will also determine the limits, if any, of Newtonian bulk and interfacial flows, necessary to define the experimental parameters for the space experiments. Specifically, the numerical simulations will identify rotation rates over which Newtonian behavior is expected. The results will help design the experiment, in terms of motor speeds, ring thickness-to-diameter ratio, etc. which will determine how much shear will be imparted on the protein solution, and its distribution at the interface versus the bulk. Subsequently, the experimental measurements of the velocity distribution on the surface of the drop will focus primarily in the regions between the rings where shear is expected to be large, unless of course numerical predictions suggest otherwise. Experiments modifying the drop radius by 50% will test the theoretical scaling of shear rates, ring radius, etc. for a range of non-dimensional governing parameters, including the Reynolds number, so that we can be confident that the model is describing the small-scale ground-based experiment to sufficient accuracy in light of the effects being ignored, such as buoyancy driven circulation and sagging

Description

The PI Lopez will contribute to the design of the experimental
protocols to examine the hydrodynamic stability of drops in the ring
shear drop (RSD) device, particularly during the recapture phase at
the end of the experiment. He will also contribute to the analysis and
dissemination of the experimental results.

There will be close co-ordination between the ASU and the RPI groups,
primarily via weekly group conference calls using skype, as well as
two one-week visits to RPI.
StatusActive
Effective start/end date9/1/139/30/20

Funding

  • National Aeronautics Space Administration (NASA): $282,517.00

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microgravity
shear
rings
velocity distribution
proteins
flow stability
viscometers
radii
buoyancy
Navier-Stokes equation
Reynolds number
simulation
hydrodynamics
viscosity
scaling
profiles
predictions