Influence of the Transverse Temperature Drop on the Stability of Two-Layer Fluid Flows with Evaporation

2019 ◽  
Vol 54 (5) ◽  
pp. 603-613
Author(s):  
I. A. Shefer
Keyword(s):  
Temperature Drop ◽  
Fluid Flows ◽  
Transverse Temperature ◽  
The Stability

scholarly journals Soft channel formation and symmetry breaking in exotic active emulsions

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
L. N. Carenza ◽  
G. Gonnella ◽  
A. Lamura ◽  
D. Marenduzzo ◽  
G. Negro ◽  
...  
Keyword(s):  
Shear Rate ◽  
Rheological Properties ◽  
Self Assembly ◽  
Contractile Activity ◽  
Active Material ◽  
Fluid Flows ◽  
Shear Rates ◽  
Two Phases ◽  
The Stability ◽  
Isotropic Fluid

Abstract We use computer simulations to study the morphology and rheological properties of a bidimensional emulsion resulting from a mixture of a passive isotropic fluid and an active contractile polar gel, in the presence of a surfactant that favours the emulsification of the two phases. By varying the intensity of the contractile activity and of an externally imposed shear flow, we find three possible morphologies. For low shear rates, a simple lamellar state is obtained. For intermediate activity and shear rate, an asymmetric state emerges, which is characterized by shear and concentration banding at the polar/isotropic interface. A further increment in the active forcing leads to the self-assembly of a soft channel where an isotropic fluid flows between two layers of active material. We characterize the stability of this state by performing a dynamical test varying the intensity of the active forcing and shear rate. Finally, we address the rheological properties of the system by measuring the effective shear viscosity, finding that this increases as active forcing is increased—so that the fluid thickens with activity.

scholarly journals Encapsulation of Lutein via Microfluidic Technology: Evaluation of Stability and In Vitro Bioaccessibility

Foods ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 2646
Author(s):  
Yuanhang Yao ◽  
Jiaxing Jansen Lin ◽  
Xin Yi Jolene Chee ◽  
Mei Hui Liu ◽  
Saif A. Khan ◽  
...  
Keyword(s):  
Bioactive Compounds ◽  
Fluid Flows ◽  
Technology Evaluation ◽  
Delivery Vehicle ◽  
Microfluidic Technology ◽  
Age Related ◽  
In Vitro Bioaccessibility ◽  
Control Fluid ◽  
The Stability

Inadequate intake of lutein is relevant to a higher risk of age-related eye diseases. However, lutein has been barely incorporated into foods efficiently because it is prone to degradation and is poorly bioaccessible in the gastrointestinal tract. Microfluidics, a novel food processing technology that can control fluid flows at the microscale, can enable the efficient encapsulation of bioactive compounds by fabricating suitable delivery structures. Hence, the present study aimed to evaluate the stability and the bioaccessibility of lutein that is encapsulated in a new noodle-like product made via microfluidic technology. Two types of oils (safflower oil (SO) and olive oil (OL)) were selected as a delivery vehicle for lutein, and two customized microfluidic devices (co-flow and combination-flow) were used. Lutein encapsulation was created by the following: (i) co-flow + SO, (ii) co-flow + OL, (iii) combination-flow + SO, and (iv) combination-flow + OL. The initial encapsulation of lutein in the noodle-like product was achieved at 86.0 ± 2.7%. Although lutein’s stability experienced a decreasing trend, the retention of lutein was maintained above 60% for up to seven days of storage. The two types of device did not result in a difference in lutein bioaccessibility (co-flow: 3.1 ± 0.5%; combination-flow: 3.6 ± 0.6%) and SO and OL also showed no difference in lutein bioaccessibility (SO: 3.4 ± 0.8%; OL: 3.3 ± 0.4%). These results suggest that the types of oil and device do not affect the lutein bioaccessibility. Findings from this study may provide scientific insights into emulsion-based delivery systems that employ microfluidics for the encapsulation of bioactive compounds into foods.

scholarly journals The relative conformational stability of the alcohol dehydrogenase alleloenzymes of the fruitfly Drosophila melanogaster

1981 ◽  
Vol 197 (1) ◽  
pp. 111-117 ◽  
Author(s):  
D R Thatcher ◽  
R Sheikh
Keyword(s):  
Drosophila Melanogaster ◽  
Alcohol Dehydrogenase ◽  
Conformational Stability ◽  
Effect Of Temperature ◽  
Net Charge ◽  
Subunit Dissociation ◽  
Naturally Occurring ◽  
Transverse Temperature ◽  
The Stability ◽  
Temperature Optima

The effect of temperature on four purified alleloenzymes of the alcohol dehydrogenase (Adhs, Adhf, AdhD and Adhn-5) of the fruitfly Drosophila melanogaster was investigated in detail. Initial-velocity studies showed that the naturally occurring Adhf and Adhs enzymes differed only in their temperature optima, and evidence of kinetic adaptation to high and low temperature was not apparent. All four alleloenzymes denatured irreversibly on heating purified enzyme solutions at pH 6.0. This technique revealed only small differences in thermostability between Adhf and Adhs, although the two mutant enzymes from AdhD and Adhn-5 were considerably more labile. Electrophoresis of the enzymes though a stable transverse temperature gradient proved to be a discriminating and reproducible technique. Enzymes of different net charge were compared on the same polyacrylamide gel. The Adhf enzyme was shown to be significantly less stable than the Adhs enzyme. Subunit interchange was observed at temperatures below the point at which the unfolding occurred. At pH 4.0, the Adhf/Adhs heterodimer was as stable as the Adhs homodimeric enzyme, and more stable than the Adhf homodimer. Adhn-5 and AdhD alleloenzymes were relatively thermolabile. The stability of the alleloenzymes towards urea denaturation was studied by urea-gradient electrophoresis. Only small differences in stability between the Adhf and Adhs enzymes were observed. The AdhD and Adhn-5 mutants were denatured at the same urea concentration, which was much lower than in the case of the wild-type enzymes. Except at pH 4.0, subunit dissociation could not be distinguished from the unfolding of the monomer.

scholarly journals Resonant Weibel instability in counterstreaming plasmas with temperature anisotropies

2009 ◽  
Vol 76 (1) ◽  
pp. 49-56 ◽  
Author(s):  
M. LAZAR ◽  
M. E. DIECKMANN ◽  
S. POEDTS
Keyword(s):  
Plasma Temperature ◽  
Thermal Velocity ◽  
Temperature Anisotropy ◽  
Large Wave ◽  
Thermal Emissions ◽  
Weibel Instability ◽  
Wave Numbers ◽  
Transverse Temperature ◽  
New Feature ◽  
The Stability

AbstractThe Weibel instability, driven by a plasma temperature anisotropy, is non-resonant with plasma particles: it is purely growing in time, and does not oscillate. The effect of a counterstreaming plasma is examined. In a counterstreaming plasma with an excess of transverse temperature, the Weibel instability arises along the streaming direction. Here it is proved that for large wave-numbers the instability becomes resonant with a finite real (oscillation) frequency, ωr ≠ 0. When the plasma flows faster, with a bulk velocity larger than the parallel thermal velocity, the instability becomes dominantly resonant. This new feature of the Weibel instability can be relevant for astrophysical sources of non-thermal emissions and the stability of counterflowing plasma experiments.

On Modelling The Stability Of Fluid Flows In Compliant Pipes Applied To Hemodynamic Problems

2015 ◽  
Vol 10 (4) ◽  
pp. 29-42
Author(s):  
Andrey Boiko
Keyword(s):  
Hydrodynamic Instability ◽  
Fluid Flows ◽  
Physical Models ◽  
Compliant Walls ◽  
The Stability

The study is directed to formulate physical models adequate to describe mechanisms of interactions of compliant walls of pipes and hydrodynamic disturbances aiming to reveal the conditions responsible for hydrodynamic instability in hemodynamic problems.

scholarly journals Stability of Individuals during Urban Inundations: What Should We Learn from Field Observations?

Geosciences ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 341 ◽  
Author(s):  
Hubert Chanson ◽  
Richard Brown
Keyword(s):  
Real Life ◽  
Fluid Flows ◽  
Field Measurements ◽  
Topographic Effects ◽  
Hydrodynamic Instabilities ◽  
Flood Events ◽  
Flow Conditions ◽  
Life Impact ◽  
Flood Flows ◽  
The Stability

The flooding of urbanized areas constitutes a major hazard to populations and infrastructure. Flood flows during urban inundations have been studied only recently and the real-life impact of fluid flows on individuals is not well understood. The stability of individuals in floodwaters is re-assessed based upon the re-analysis of detailed field measurements during a major flood event. The results emphasized that hydrodynamic instabilities, linked to local topographic effects and debris, constitute major real-world hazards. A comparison between a number of flow conditions deemed unsafe for individuals, along with guidelines, suggests that many recommendations are over-optimistic and unsafe in real floodwaters and natural disasters. A series of more conservative guidelines is proposed, particularity relevant to flood events.

GRAVITATIONAL AND MAGNETIC CONVECTION IN MAGNETIC FLUID

2005 ◽  
Vol 19 (07n09) ◽  
pp. 1367-1373
Author(s):  
A. A. BOZHKO ◽  
G. F. PUTIN
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Solid Phase ◽  
Fluid Flows ◽  
Homogeneous Magnetic Field ◽  
Temperature Sensors ◽  
Cylindrical Layer ◽  
Temperature Sensitive ◽  
Concentration Gradients ◽  
The Stability

Experiments were performed to examine the influence of external homogeneous magnetic field on ferrofluid convection in thin cylindrical layer heated from one wide sidewall and cooled from another. Gravitational and magnetic mechanisms of convection as well as the influence of gravitational sedimentation of particles and their aggregates on stability and structure of fluid flows are studied. The integral and local temperature sensors were used for measurement of heat transport across the layer. Visualization of flow patterns was provided by a temperature-sensitive liquid crystal sheet. The results indicate that with the help of a magnetic field it is possible to control the stability and the form of convection motions. Besides, the concentration gradients of solid phase can have material role to convection instability and heat transfer.

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