scholarly journals Phase-Field Modeling of Freeze Concentration of Protein Solutions

Polymers ◽  
2018 ◽  
Vol 11 (1) ◽  
pp. 10 ◽  
Author(s):  
Tai-Hsi Fan ◽  
Ji-Qin Li ◽  
Bruna Minatovicz ◽  
Elizabeth Soha ◽  
Li Sun ◽  
...  
Keyword(s):  
Phase Field ◽  
Liquid Solution ◽  
Solute Concentration ◽  
Ice Crystals ◽  
Mean Field Approximation ◽  
Solution Viscosity ◽  
Bulk Solution ◽  
Freezing Process ◽  
Freeze Concentration ◽  
Solute Exclusion

Bulk solutions of therapeutic proteins are often frozen for long-term storage. During the freezing process, proteins in liquid solution redistribute and segregate in the interstitial space between ice crystals. This is due to solute exclusion from ice crystals, higher viscosity of the concentrated solution, and space confinement between crystals. Such segregation may have a negative impact on the native conformation of protein molecules. To better understand the mechanisms, we developed a phase-field model to describe the growth of ice crystals and the dynamics of freeze concentration at the mesoscale based on mean field approximation of solute concentration and the underlying heat, mass and momentum transport phenomena. The model focuses on evolution of the interfaces between liquid solution and ice crystals, and the degree of solute concentration due to partition, diffusive, and convective effects. The growth of crystals is driven by cooling of the bulk solution, but suppressed by a higher solute concentration due to increase of solution viscosity, decrease of freezing point, and the release of latent heat. The results demonstrate the interplay of solute exclusion, space confinement, heat transfer, coalescence of crystals, and the dynamic formation of narrow gaps between crystals and Plateau border areas along with correlations of thermophysical properties in the supercooled regime.

The impact of ι‐ and κ‐carrageenan addition on freezing process and ice crystals structure of strawberry sorbet frozen by various methods

2019 ◽  
Vol 85 (1) ◽  
pp. 50-56 ◽  
Author(s):  
Anna Kamińska‐Dwórznicka ◽  
Agnieszka Janczewska‐Dupczyk ◽  
Anna Kot ◽  
Sylwia Łaba ◽  
Katarzyna Samborska
Keyword(s):  
Ice Crystals ◽  
Freezing Process ◽  
The Impact

scholarly journals Concentration profiles around and chemical composition within growing multicomponent bubble in presence of curvature and viscous effects

2020 ◽  
Vol 92 (7) ◽  
pp. 1123-1133 ◽  
Author(s):  
Anatoly E. Kuchma ◽  
Alexander K. Shchekin
Keyword(s):  
Chemical Composition ◽  
Scale Effects ◽  
Liquid Solution ◽  
Solution Viscosity ◽  
Supersaturated Solution ◽  
Concentration Profiles ◽  
Viscous Effects ◽  
Stationary Diffusion ◽  
Multicomponent Gas ◽  
Viscous Solution

AbstractThe regularities of changing chemical composition and size of a ultra-small multicomponent gas bubble growing in a viscous solution have been analyzed. The full-scale effects of solution viscosity and bubble curvature at non-stationary diffusion of arbitrary number of dissolved gases with any value of gas supersaturations and solubilities in the surrounding liquid solution have been taken into account. The nonuniform concentration profiles of gas species in supersaturated solution around the growing bubble with changing composition have been found as a function of time and distance from the bubble center. Equations describing transition to stationary concentrations of gases in the bubble with increasing radius have been obtained. Analytic asymptotic solutions of these equations for a ternary system have been presented.

Experimental studies on washing and melting ice crystals in the immiscible refrigerant freezing process

Desalination ◽  
1974 ◽  
Vol 14 (3) ◽  
pp. 263-290 ◽  
Author(s):  
W.H. Denton ◽  
M.J.S. Smith ◽  
J.T. Klaschka ◽  
R. Forgan ◽  
H.R. Diffey ◽  
...  
Keyword(s):  
Experimental Studies ◽  
Ice Crystals ◽  
Freezing Process

scholarly journals Restricted intramolecular rotation of fluorescent molecular rotors at the periphery of aqueous microdroplets in oil

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jooyoun Kang ◽  
SangMoon Lhee ◽  
Jae Kyoo Lee ◽  
Richard N. Zare ◽  
Hong Gil Nam
Keyword(s):  
Fluorescence Intensity ◽  
Solution Viscosity ◽  
Bulk Solution ◽  
Molecular Rotor ◽  
Reaction Conditions ◽  
Dominant Mechanism ◽  
Alexa Fluor ◽  
Fluorescent Molecular Rotors ◽  
Phase Chemistry ◽  
Intramolecular Rotation

Abstract Fluorescent molecular rotor dyes, including Cy3, Cy5, and Alexa Fluor 555, dissolved in micron-sized aqueous droplets (microdroplets) in oil were excited, and the fluorescence intensity was recorded as function of time. We observed lengthening of the fluorescence lifetime of these dyes at the water–oil periphery, which extended several microns inward. This behavior shows that intramolecular rotation is restricted at and near the microdroplet interface. Lengthened lifetimes were observed in water microdroplets but not in microdroplets composed of organic solvents. This lifetime change was relatively insensitive to added glycerol up to 60%, suggesting that solution viscosity is not the dominant mechanism. These restricted intramolecular rotations at and near the microdroplet periphery are consistent with the reduced entropy observed in chemical reactions in microdroplets compared to the same reaction conditions in bulk solution and helps us further understand why microdroplet chemistry differs so markedly from bulk-phase chemistry.

scholarly journals Growth of ice crystals and secondary nucleation velocity during freeze concentration.

1987 ◽  
Vol 24 (6) ◽  
pp. 401-406
Author(s):  
Kazuhiro NAKANISHI ◽  
Yoshihito SHIRAI ◽  
Ryuichi MATSUNO
Keyword(s):  
Ice Crystals ◽  
Secondary Nucleation ◽  
Freeze Concentration

An Approximate Model of the Process of Non-Dendritic Morphology Formation in Solidification of Binary Melt under Stirring

2019 ◽  
Vol 22 (4) ◽  
pp. 367-374
Author(s):  
Yu. A. Lebedinsky ◽  
A. M. Branovitsky ◽  
V. A. Dement'ev
Keyword(s):  
Crystal Growth ◽  
Phase Field ◽  
Approximate Model ◽  
Solute Concentration ◽  
Field Method ◽  
Dendritic Morphology ◽  
Phase Field Method ◽  
Primary Crystal ◽  
Initial Concentration

The primary crystal growth in a binary melt is modeled on the base of the phase field method with approximate consideration of melt stirring. Changes in the second component (solute) concentration near a solidification area during stirring are considered as a main reason of modification of dendritic morphology of crystals. An effect of stirring is approximately simulated as forced changes in the solute concentration by either resetting to initial concentration, or averaging concentration. Dendritic morphology is shown to change to rosette and then to globular one depending on space parameters of forced changes.

Limitations in the use of electrical conductivity to monitor the behaviour of soil solution

Soil Research ◽  
2006 ◽  
Vol 44 (7) ◽  
pp. 695 ◽  
Author(s):  
D. A. Rose ◽  
F. Abbas ◽  
M. A. Adey
Keyword(s):  
Electrical Conductivity ◽  
Solution Concentration ◽  
Solute Concentration ◽  
Breakthrough Curves ◽  
Time Domain Reflectometry ◽  
Solid Particles ◽  
Bulk Solution ◽  
Hydrodynamic Dispersion ◽  
Wide Range ◽  
The Individual

Solutions of KBr and K2SO4 of various concentrations were separately displaced by deionised water through 2 contrasting saturated materials, inert solid particles (glass ballotini), and a reactive but non-swelling aggregated clay mineral (sepiolite) over a wide range of flow rates. The concentration of the individual ions in the effluent was analysed (Br– and K+ with ion-specific electrodes, SO42+ by ion chromatography) and that of bulk solution was measured by electrical conductivity (EC). For each displacement, the individual breakthrough curves (BTCs) for the anion, the cation, and the bulk solution were optimised by CXTFIT 2.0. In ballotini, the BTCs of the anion, cation, and solution were always congruent, the retardation factors did not differ significantly from unity, and the coefficients of hydrodynamic dispersion were identical. For sepiolite, the ions were separated; the bulk solution eluted faster than the cation, slower than the anions. Retardation factors were always less than unity for the anions, greater than unity for the cation, and close to but less than unity for the bulk solution, and became more extreme as the concentration of solute decreased. Dispersion coefficients were, however, unaffected by type of solute, concentration range, or particular ion/EC. The separation of ions means that the composition as well as the concentration of a solution changes continuously during flow through a reactive soil. Estimates of solution concentration from measurements of EC may thus fail to characterise adequately the movement of the individual components of the solution in such materials. This has implications for the interpretation of any leachate monitoring in reactive soils by methods based on the measurement of EC, such as time-domain reflectometry.

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