In situ polymer flocculation and growth in Taylor–Couette flows

Soft Matter ◽  
2018 ◽  
Vol 14 (42) ◽  
pp. 8627-8635 ◽  
Author(s):  
Athena Metaxas ◽  
Nikolas Wilkinson ◽  
Ellie Raethke ◽  
Cari S. Dutcher
Keyword(s):  
Polymer Particle ◽  
Hydrodynamic Flow ◽  
Flow State ◽  
Couette Cell ◽  
Taylor Couette ◽  
Polymer Flocculation

Transient, in situ polymer-particle flocculation and growth was studied as a function of hydrodynamic flow state using a modified Taylor–Couette cell.

Impact of osmotic pressure on the stability of Taylor vortices

2022 ◽  
Vol 933 ◽  
Author(s):  
Rouae Ben Dhia ◽  
Nils Tilton ◽  
Denis Martinand
Keyword(s):  
Osmotic Pressure ◽  
Critical Conditions ◽  
Hydrodynamic Instabilities ◽  
Taylor Vortices ◽  
Dynamic Filtration ◽  
Analytical Criterion ◽  
Permeable Cylinders ◽  
Couette Cell ◽  
Taylor Couette ◽  
The Stability

We use linear stability analysis and direct numerical simulations to investigate the coupling between centrifugal instabilities, solute transport and osmotic pressure in a Taylor–Couette configuration that models rotating dynamic filtration devices. The geometry consists of a Taylor–Couette cell with a superimposed radial throughflow of solvent across two semi-permeable cylinders. Both cylinders totally reject the solute, inducing the build-up of a concentration boundary layer. The solute retroacts on the velocity field via the osmotic pressure associated with the concentration differences across the semi-permeable cylinders. Our results show that the presence of osmotic pressure strongly alters the dynamics of the centrifugal instabilities and substantially reduces the critical conditions above which Taylor vortices are observed. It is also found that this enhancement of the hydrodynamic instabilities eventually plateaus as the osmotic pressure is further increased. We propose a mechanism to explain how osmosis and instabilities cooperate and develop an analytical criterion to bound the parameter range for which osmosis fosters the hydrodynamic instabilities.

Ionic strength and polyelectrolyte molecular weight effects on floc formation and growth in Taylor–Couette flows

Soft Matter ◽  
2021 ◽  
Author(s):  
Athena E. Metaxas ◽  
Vishal Panwar ◽  
Ruth L. Olson ◽  
Cari S. Dutcher
Keyword(s):  
Molecular Weight ◽  
Ionic Strength ◽  
Solution Ionic Strength ◽  
Radial Injection ◽  
Couette Cell ◽  
Taylor Couette

A Taylor–Couette cell capable of radial injection was used to study the effects of varying solution ionic strength and polyelectrolyte molecular weight on the polyelectrolyte-driven flocculation of bentonite suspensions.

In Situ Formation of Gold Nanoparticles within a Polymer Particle and Their Catalytic Activities in Various Chemical Reactions

ChemPhysChem ◽  
2018 ◽  
Vol 20 (1) ◽  
pp. 70-77 ◽  
Author(s):  
Wongi Jang ◽  
Richard Taylor ◽  
Pascal N. Eyimegwu ◽  
Hongsik Byun ◽  
Jun-Hyun Kim
Keyword(s):  
Gold Nanoparticles ◽  
Chemical Reactions ◽  
Polymer Particle ◽  
Catalytic Activities ◽  
In Situ Formation

scholarly journals Polypropylene Nanocomposites Obtained byIn SituPolymerization Using Metallocene Catalyst: Influence of the Nanoparticles on the Final Polymer Morphology

2012 ◽  
Vol 2012 ◽  
pp. 1-6 ◽  
Author(s):  
Paula Zapata ◽  
Raúl Quijada
Keyword(s):  
Catalytic System ◽  
Sol Gel ◽  
Metallocene Catalyst ◽  
Particle Morphology ◽  
Polymer Particle ◽  
Silica Nanospheres ◽  
Sem Images ◽  
Transmission Electron ◽  
Polypropylene Nanocomposites

Polypropylene nanocomposites containing silica nanospheres based on the sol-gel methods were produced viain situpolymerization using a rac-Et(Ind)2ZrCl2/methylaluminoxane (MAO) system. Two different routes were used depending on the interaction between the silica nanoparticles with the catalytic system. In route 1 the nanoparticles were added together with the catalytic system (rac-Et(Ind)2ZrCl2)/(MAO) directly into the reactor, and in route 2 the metallocene rac-Et(Ind)2ZrCl2was supported on silica nanospheres pretreated with (MAO). SEM images show that when the nanospheres were added by both routes, they were replicated in the final polymer particle morphology; this phenomenon was more pronounced for PP obtained by route 2. The polypropylene (PP) nanocomposites obtained by both routes had a slightly higher percent crystallinities and crystallinity temperatures than pure PP. Transmission electron microscopy (TEM) images show that the nanospheres were well dispersed into the polypropylene matrix, particularly in the nanocomposites obtained by the support system (route 2).

scholarly journals Inducing protein aggregation by extensional flow

2017 ◽  
Vol 114 (18) ◽  
pp. 4673-4678 ◽  
Author(s):  
John Dobson ◽  
Amit Kumar ◽  
Leon F. Willis ◽  
Roman Tuma ◽  
Daniel R. Higazi ◽  
...  
Keyword(s):  
Flow Field ◽  
Protein Aggregation ◽  
Large Scale ◽  
Extensional Flow ◽  
Cysteine Residue ◽  
Hydrodynamic Flow ◽  
Extrinsic Factors ◽  
Aggregation Propensity ◽  
Industrial Manufacture

Relative to other extrinsic factors, the effects of hydrodynamic flow fields on protein stability and conformation remain poorly understood. Flow-induced protein remodeling and/or aggregation is observed both in Nature and during the large-scale industrial manufacture of proteins. Despite its ubiquity, the relationships between the type and magnitude of hydrodynamic flow, a protein’s structure and stability, and the resultant aggregation propensity are unclear. Here, we assess the effects of a defined and quantified flow field dominated by extensional flow on the aggregation of BSA, β2-microglobulin (β2m), granulocyte colony stimulating factor (G-CSF), and three monoclonal antibodies (mAbs). We show that the device induces protein aggregation after exposure to an extensional flow field for 0.36–1.8 ms, at concentrations as low as 0.5 mg mL−1. In addition, we reveal that the extent of aggregation depends on the applied strain rate and the concentration, structural scaffold, and sequence of the protein. Finally we demonstrate the in situ labeling of a buried cysteine residue in BSA during extensional stress. Together, these data indicate that an extensional flow readily unfolds thermodynamically and kinetically stable proteins, exposing previously sequestered sequences whose aggregation propensity determines the probability and extent of aggregation.

scholarly journals Turbulence decay towards the linearly stable regime of Taylor–Couette flow

2014 ◽  
Vol 748 ◽  
Author(s):  
Rodolfo Ostilla-Mónico ◽  
Roberto Verzicco ◽  
Siegfried Grossmann ◽  
Detlef Lohse
Keyword(s):  
Reynolds Number ◽  
Accretion Disks ◽  
Outer Cylinder ◽  
Flow State ◽  
Initial State ◽  
Stable Regime ◽  
Turbulence Decay ◽  
Taylor Couette ◽  
Cylinder Rotation ◽  
Damped Oscillator

AbstractTaylor–Couette (TC) flow is used to probe the hydrodynamical (HD) stability of astrophysical accretion disks. Experimental data on the subcritical stability of TC flow are in conflict about the existence of turbulence (cf. Ji et al. (Nature, vol. 444, 2006, pp. 343–346) and Paoletti et al. (Astron. Astroph., vol. 547, 2012, A64)), with discrepancies attributed to end-plate effects. In this paper we numerically simulate TC flow with axially periodic boundary conditions to explore the existence of subcritical transitions to turbulence when no end plates are present. We start the simulations with a fully turbulent state in the unstable regime and enter the linearly stable regime by suddenly starting a (stabilizing) outer cylinder rotation. The shear Reynolds number of the turbulent initial state is up to $Re_s \lesssim 10^5$ and the radius ratio is $\eta =0.714$. The stabilization causes the system to behave as a damped oscillator and, correspondingly, the turbulence decays. The evolution of the torque and turbulent kinetic energy is analysed and the periodicity and damping of the oscillations are quantified and explained as a function of shear Reynolds number. Though the initially turbulent flow state decays, surprisingly, the system is found to absorb energy during this decay.

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