Oscillatory Flow Between Two Hemispheres for Shearing Protein Solution

2013 ◽  
Author(s):  
Dejuan Kong ◽  
Anita Penkova ◽  
Satwindar Singh Sadhal
Keyword(s):  
Shear Rate ◽  
Shear Flow ◽  
Protein Aggregation ◽  
Oscillatory Flow ◽  
The Body ◽  
Protein Solutions ◽  
Liquid Region ◽  
Mean Flow ◽  
Protein Solution ◽  
Aggregation Rate

Protein aggregation rate is known to be influenced by shear flow in protein solutions. This has important physiological implications as many of the body functions involve shear flow. Fluid mechanical shear can affect interactions between protein molecules, initiate protein aggregation, and further affect their biological activity. The shear rate is therefore an important parameter either to determine or to influence the properties of the protein solution when it forms a nucleus or aggregates. For experiments, the number density of nuclei can be controlled by using an optimal shear rate and protein concentration. However, this requires theoretical information on the shear rate for the experimental conditions. With this motivation, we have designed an experiment in which we can effectively apply shear with flow characteristics that can be calculated. Specifically, in a small hemispherically-shaped bowl, 4 mm in diameter we place the protein solution and insert a rounded rod that can be vibrated rotationally or laterally, maintaining spherical symmetry in the liquid region. This system is particularly useful when only small quantities of expensive protein solutions can be used for experimentation. We have carried out the mathematical analysis of the time-dependent flow field between two concentric hemispheres by the perturbation method using ε = U0/ωa ≪ 1 as a small parameter where U0 is a characteristic velocity, ω is the oscillation frequency and a is a length scale based on the vessel dimensions (bowl radius). We have obtained an analytical solution for the velocity field, and the shear rate in the liquid. In addition, with the nonlinear interaction of the oscillatory flow, there is a nonzero time-independent mean flow (known as streaming). With the integrated effect of shear in the liquid region, this result will be useful for conducting aggregation experiment in which the effective shear rate can be correlated to the aggregation rate.

Oscillatory Flow Between Two Hemispheres for Shearing Protein Solution

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
Dejuan Kong ◽  
Anita Penkova ◽  
Satwindar Singh Sadhal
Keyword(s):  
Shear Rate ◽  
Oscillatory Flow ◽  
Molecular Mechanisms ◽  
Outer Boundary ◽  
Experimental System ◽  
Theoretical Background ◽  
Physical Factors ◽  
Protein Solution ◽  
Steady Streaming ◽  
And Control

Protein aggregation, one of the common molecular mechanisms for neurodegenerative diseases, is affected by variety of physical factors, one of which is shear rate of protein solution. This paper provides theoretical background on the shear rate in the experimental system we have proposed to effectively apply and control shear. We carried out the mathematical analysis of the flow field resulted from torsional or transverse oscillation on the outer boundary between two concentric hemispheres by perturbation method. We have obtained analytical solutions for the velocity field, the shear rate, and the flow pattern of steady streaming created by the nonlinear interaction of the oscillatory flow.

scholarly journals The Different Colors of mAbs in Solution

Antibodies ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 21
Author(s):  
Alexandre Ambrogelly
Keyword(s):  
Visual Inspection ◽  
Quantitative Methods ◽  
Geographical Area ◽  
Therapeutic Protein ◽  
Protein Solutions ◽  
Protein Solution ◽  
Critical Quality Attribute ◽  
Recombinant Therapeutic Protein ◽  
Protein Variants ◽  
Antibody Solution

The color of a therapeutic monoclonal antibody solution is a critical quality attribute. Consistency of color is typically assessed at time of release and during stability studies against preset criteria for late stage clinical and commercial products. A therapeutic protein solution’s color may be determined by visual inspection or by more quantitative methods as per the different geographical area compendia. The nature and intensity of the color of a therapeutic protein solution is typically determined relative to calibrated standards. This review covers the analytical methodologies used for determining the color of a protein solution and presents an overview of protein variants and impurities known to contribute to colored recombinant therapeutic protein solutions.

Heat/mass transport in shear flow over a heterogeneous surface with first-order surface-reactive domains

2015 ◽  
Vol 782 ◽  
pp. 260-299 ◽  
Author(s):  
Preyas N. Shah ◽  
Eric S. G. Shaqfeh
Keyword(s):  
Mass Transfer ◽  
Shear Rate ◽  
Shear Flow ◽  
Reaction Rate ◽  
Patch Size ◽  
Patch Area ◽  
First Order ◽  
Effective Boundary ◽  
Order Surface ◽  
Slip Distance

Surfaces that include heterogeneous mass transfer at the microscale are ubiquitous in nature and engineering. Many such media are modelled via an effective surface reaction rate or mass transfer coefficient employing the conventional ansatz of kinetically limited transport at the microscale. However, this assumption is not always valid, particularly when there is strong flow. We are interested in modelling reactive and/or porous surfaces that occur in systems where the effective Damköhler number at the microscale can be $O(1)$ and the local Péclet number may be large. In order to expand the range of the effective mass transfer surface coefficient, we study transport from a uniform bath of species in an unbounded shear flow over a flat surface. This surface has a heterogeneous distribution of first-order surface-reactive circular patches (or pores). To understand the physics at the length scale of the patch size, we first analyse the flux to a single reactive patch. We use both analytic and boundary element simulations for this purpose. The shear flow induces a 3-D concentration wake structure downstream of the patch. When two patches are aligned in the shear direction, the wakes interact to reduce the per patch flux compared with the single-patch case. Having determined the length scale of the interaction between two patches, we study the transport to a periodic and disordered distribution of patches again using analytic and boundary integral techniques. We obtain, up to non-dilute patch area fraction, an effective boundary condition for the transport to the patches that depends on the local mass transfer coefficient (or reaction rate) and shear rate. We demonstrate that this boundary condition replaces the details of the heterogeneous surfaces at a wall-normal effective slip distance also determined for non-dilute patch area fractions. The slip distance again depends on the shear rate, and weakly on the reaction rate, and scales with the patch size. These effective boundary conditions can be used directly in large-scale physics simulations as long as the local shear rate, reaction rate and patch area fraction are known.

On the irreversibility of internal-wave dynamics due to wave trapping by mean flow inhomogeneities. Part 1. Local analysis

1993 ◽  
Vol 251 ◽  
pp. 21-53 ◽  
Author(s):  
Sergei I. Badulin ◽  
Victor I. Shrira
Keyword(s):  
Shear Flow ◽  
Internal Wave ◽  
Wave Field ◽  
Large Scale ◽  
Spatial Scales ◽  
Energy Concentration ◽  
Local Analysis ◽  
Mean Flow ◽  
Wave Trapping ◽  
Wave Dynamics

The propagation of guided internal waves on non-uniform large-scale flows of arbitrary geometry is studied within the framework of linear inviscid theory in the WKB-approximation. Our study is based on a set of Hamiltonian ray equations, with the Hamiltonian being determined from the Taylor-Goldstein boundary-value problem for a stratified shear flow. Attention is focused on the fundamental fact that the generic smooth non-uniformities of the large-scale flow result in specific singularities of the Hamiltonian. Interpreting wave packets as particles with momenta equal to their wave vectors moving in a certain force field, one can consider these singularities as infinitely deep potential holes acting quite similarly to the ‘black holes’ of astrophysics. It is shown that the particles fall for infinitely long time, each into its own ‘black hole‘. In terms of a particular wave packet this falling implies infinite growth with time of the wavenumber and the amplitude, as well as wave motion focusing at a certain depth. For internal-wave-field dynamics this provides a robust mechanism of a very specific conservative and moreover Hamiltonian irreversibility.This phenomenon was previously studied for the simplest model of the flow non-uniformity, parallel shear flow (Badulin, Shrira & Tsimring 1985), where the term ‘trapping’ for it was introduced and the basic features were established. In the present paper we study the case of arbitrary flow geometry. Our main conclusion is that although the wave dynamics in the general case is incomparably more complicated, the phenomenon persists and retains its most fundamental features. Qualitatively new features appear as well, namely, the possibility of three-dimensional wave focusing and of ‘non-dispersive’ focusing. In terms of the particle analogy, the latter means that a certain group of particles fall into the same hole.These results indicate a robust tendency of the wave field towards an irreversible transformation into small spatial scales, due to the presence of large-scale flows and towards considerable wave energy concentration in narrow spatial zones.

Dynamics of a non-spherical microcapsule with incompressible interface in shear flow

2011 ◽  
Vol 678 ◽  
pp. 221-247 ◽  
Author(s):  
P. M. VLAHOVSKA ◽  
Y.-N. YOUNG ◽  
G. DANKER ◽  
C. MISBAH
Keyword(s):  
Shear Rate ◽  
Shear Flow ◽  
Viscosity Ratio ◽  
Perturbation Expansion ◽  
Shear Plane ◽  
Creeping Flow ◽  
Regular Perturbation ◽  
Cell Dynamics ◽  
Initial Shape ◽  
Flow Equations

We study the motion and deformation of a liquid capsule enclosed by a surface-incompressible membrane as a model of red blood cell dynamics in shear flow. Considering a slightly ellipsoidal initial shape, an analytical solution to the creeping-flow equations is obtained as a regular perturbation expansion in the excess area. The analysis takes into account the membrane fluidity, area-incompressibility and resistance to bending. The theory captures the observed transition from tumbling to swinging as the shear rate increases and clarifies the effect of capsule deformability. Near the transition, intermittent behaviour (swinging periodically interrupted by a tumble) is found only if the capsule deforms in the shear plane and does not undergo stretching or compression along the vorticity direction; the intermittency disappears if deformation along the vorticity direction occurs, i.e. if the capsule ‘breathes’. We report the phase diagram of capsule motions as a function of viscosity ratio, non-sphericity and dimensionless shear rate.

Effects of shear rate on rouleau formation in simple shear flow

Biorheology ◽  
1988 ◽  
Vol 25 (1-2) ◽  
pp. 113-122 ◽  
Author(s):  
T. Murata ◽  
T.W. Secomb
Keyword(s):  
Shear Rate ◽  
Shear Flow ◽  
Simple Shear ◽  
Simple Shear Flow ◽  
Rouleau Formation

scholarly journals The Cumulative Effects of Forest Disturbance and Climate Variability on Streamflow in the Deadman River Watershed

Forests ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 196 ◽  
Author(s):  
Krysta Giles-Hansen ◽  
Qiang Li ◽  
Xiaohua Wei
Keyword(s):  
Climate Variability ◽  
Forest Cover ◽  
Forest Disturbance ◽  
Climatic Variability ◽  
High Flow ◽  
The Body ◽  
Cumulative Effects ◽  
Low Flow ◽  
Mean Flow ◽  
River Watershed

Climatic variability and cumulative forest cover change are the two dominant factors affecting hydrological variability in forested watersheds. Separating the relative effects of each factor on streamflow is gaining increasing attention. This study adds to the body of literature by quantifying the relative contributions of those two drivers to the changes in annual mean flow, low flow, and high flow in a large forested snow dominated watershed, the Deadman River watershed (878 km2) in the Southern Interior of British Columbia, Canada. Over the study period of 1962 to 2012, the cumulative effects of forest disturbance significantly affected the annual mean streamflow. The effects became statistically significant in 1989 at the cumulative forest disturbance level of 12.4% of the watershed area. The modified double mass curve and sensitivity-based methods consistently revealed that forest disturbance and climate variability both increased annual mean streamflow during the disturbance period (1989–2012), with an average increment of 14 mm and 6 mm, respectively. The paired-year approach was used to further investigate the relative contributions to low and high flows. Our analysis showed that low and high flow increased significantly by 19% and 58%, respectively over the disturbance period (p < 0.05). We conclude that forest disturbance and climate variability have significantly increased annual mean flow, low flow and high flow over the last 50 years in a cumulative and additive manner in the Deadman River watershed.

Unsteady disturbances of streaming motions around bodies

1989 ◽  
Vol 209 ◽  
pp. 385-403 ◽  
Author(s):  
H. M. Atassi ◽  
J. Grzedzinski
Keyword(s):  
Wave Equation ◽  
Body Surface ◽  
Source Term ◽  
The Body ◽  
Entire Body ◽  
Two Dimensional ◽  
Mean Flow ◽  
Inhomogeneous Wave ◽  
Inhomogeneous Wave Equation ◽  
The Mean

For small-amplitude vortical and entropic unsteady disturbances of potential flows, Goldstein proposed a partial splitting of the velocity field into a vortical part u(I) that is a known function of the imposed upstream disturbance and a potential part ∇ϕ satisfying a linear inhomogeneous wave equation with a dipole-type source term. The present paper deals with flows around bodies with a stagnation point. It is shown that for such flows u(I) becomes singular along the entire body surface and its wake and as a result ∇ϕ will also be singular along the entire body surface. The paper proposes a modified splitting of the velocity field into a vortical part u(R) that has zero streamwise and normal components along the body surface, an entropy-dependent part and a regular part ∇ϕ* that satisfies a linear inhomogeneous wave equation with a modified source term.For periodic disturbances, explicit expressions for u(R) are given for three-dimensional flows past a single obstacle and for two-dimensional mean flows past a linear cascade. For weakly sheared flows, it is shown that if the mean flow has only a finite number of isolated stagnation points, u(R) will be finite along the body surface. On the other hand, if the mean flow has a stagnation line along the body surface such as in two-dimensional flows then the component of u(R) in this direction will have a logarithmic singularity.For incompressible flows, the boundary-value problem for ϕ* is formulated in terms of an integral equation of the Fredholm type. The theory is applied to a typical bluff body. Detailed calculations are carried out to show the velocity and pressure fields in response to incident harmonic disturbances.

scholarly journals Use of Viscosity to Probe the Interaction of Anionic Surfactants with a Coagulant Protein from Moringa oleifera Seeds

2009 ◽  
Vol 2009 ◽  
pp. 1-5 ◽  
Author(s):  
Raymond Maikokera ◽  
Habauka M. Kwaambwa
Keyword(s):  
Moringa Oleifera ◽  
Anionic Surfactants ◽  
Sodium Dodecyl ◽  
Sodium Dodecyl Benzene Sulfonate ◽  
Protein Solutions ◽  
Capillary Viscometer ◽  
Protein Solution ◽  
V Protein ◽  
Dodecyl Benzene Sulfonate ◽  
Physical Quantities

The intrinsic viscosity of the coagulant protein was evaluated from the flow times of the protein solutions through a capillary viscometer, and the results suggested the coagulant protein to be globular. The interactions of the coagulant protein with anionic surfactant sodium dodecyl sulphate (SDS) and sodium dodecyl benzene sulfonate (SDBS) were also investigated by capillary viscometry. We conclude that there is strong protein-surfactant interaction at very low surfactant concentrations, and the behavior of the anionic surfactants in solutions containing coagulant protein is very similar. The viscometry results of protein-SDS system are compared with surface tension, fluorescence, and circular dichroism reported earlier. Combining the results of the four studies, the four approaches seem to confirm the same picture of the coagulant protein-SDS interaction. All the physical quantities when studied as function of surfactant concentration for 0.05% (w/v) protein solution either exhibited a maximum or minimum at a critical SDS concentration.

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