scholarly journals Dynamic Surface Tension Enhances the Stability of Nanobubbles in Xylem Sap

2021 ◽  
Vol 12 ◽  
Author(s):  
Stephen Ingram ◽  
Yann Salmon ◽  
Anna Lintunen ◽  
Teemu Hölttä ◽  
Timo Vesala ◽  
...  
Keyword(s):  
Surface Tension ◽  
Surface Composition ◽  
Xylem Sap ◽  
Dynamic Surface Tension ◽  
External Pressure ◽  
Nucleation Theory ◽  
Classical Nucleation Theory ◽  
Dynamic Surface ◽  
Biologically Relevant ◽  
Dynamics Simulations

Air seeded nanobubbles have recently been observed within tree sap under negative pressure. They are stabilized by an as yet unidentified process, although some embolize their vessels in extreme circumstances. Current literature suggests that a varying surface tension helps bubbles survive, but few direct measurements of this quantity have been made. Here, we present calculations of dynamic surface tension for two biologically relevant lipids using molecular dynamics simulations. We find that glycolipid monolayers resist expansion proportionally to the rate of expansion. Their surface tension increases with the tension applied, in a similar way to the viscosity of a non-Newtonian fluid. In contrast, a prototypical phospholipid was equally resistant to all applied tensions, suggesting that the fate of a given nanobubble is dependent on its surface composition. By incorporating our results into a Classical Nucleation Theory (CNT) framework, we predict nanobubble stability with respect to embolism. We find that the metastable radius of glycolipid coated nanobubbles is approximately 35 nm, and that embolism is in this case unlikely when the external pressure is less negative than –1.5 MPa.

Dynamic surface tension of xylem sap lipids

2020 ◽  
Vol 40 (4) ◽  
pp. 433-444 ◽  
Author(s):  
Jinlong Yang ◽  
Joseph M Michaud ◽  
Steven Jansen ◽  
H Jochen Schenk ◽  
Yi Y Zuo
Keyword(s):  
Surface Tension ◽  
Surface Area ◽  
Xylem Sap ◽  
Dynamic Surface Tension ◽  
Liquid Interfaces ◽  
Surface Tensions ◽  
Local Surface ◽  
Dynamic Surface ◽  
Equilibrium Surface ◽  
Pit Membrane

Abstract The surface tension of xylem sap has been traditionally assumed to be close to that of the pure water because decreasing surface tension is thought to increase vulnerability to air seeding and embolism. However, xylem sap contains insoluble lipid-based surfactants, which also coat vessel and pit membrane surfaces, where gas bubbles can enter xylem under negative pressure in the process known as air seeding. Because of the insolubility of amphiphilic lipids, the surface tension influencing air seeding in pit pores is not the equilibrium surface tension of extracted bulk sap but the local surface tension at gas–liquid interfaces, which depends dynamically on the local concentration of lipids per surface area. To estimate the dynamic surface tension in lipid layers that line surfaces in the xylem apoplast, we studied the time-dependent and surface area-regulated surface tensions of apoplastic lipids extracted from xylem sap of four woody angiosperm plants using constrained drop surfactometry. Xylem lipids were found to demonstrate potent surface activity, with surface tensions reaching an equilibrium at ~25 mN m-1 and varying between a minimum of 19 mN m-1 and a maximum of 68 mN m-1 when changing the surface area between 50 and 160% around the equilibrium surface area. It is concluded that xylem lipid films in natural conditions most likely range from nonequilibrium metastable conditions of a supersaturated compression state to an undersaturated expansion state, depending on the local surface areas of gas–liquid interfaces. Together with findings that maximum pore constrictions in angiosperm pit membranes are much smaller than previously assumed, low dynamic surface tension in xylem turns out to be entirely compatible with the cohesion–tension and air-seeding theories, as well as with the existence of lipid-coated nanobubbles in xylem sap, and with the range of vulnerabilities to embolism observed in plants.

Visualization of Multiscale Processes - Bubble Dynamics in Surface Active Colloids

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
S. Manoharan ◽  
D. Kalaikadal ◽  
R. M. Manglik ◽  
E. Iskrenova-Ekiert ◽  
S. S. Patnaik
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Pure Water ◽  
Dynamic Surface Tension ◽  
Air Flow Rate ◽  
Dynamic Surface ◽  
Multi Scale ◽  
Macro Scale ◽  
Dynamics Simulations ◽  
Adsorption Desorption

The growth dynamics of isolated gas bubbles from a submerged capillary-tube orifice in a pool of aqueous solution of Cetyl Trimethyl Ammonium Bromide (CTAB) was studied by multi-scale modeling. The macro-scale bubble ebullience is controlled by the molecular scale surfactant adsorption/desorption on the liquid-gas interface. Molecular dynamics simulations were carried out to predict the interfacial adsorption/desorption kinetics. The results of the molecular dynamics simulations were input to the volume-of-fluid based macro-scale computations. The size and shape of bubbles from incipience to departure were measured using high speed videography for model validation. Predictions of the multi-scale model agree with the experimental measurements of bubble size evolution and bubble diameter at departure. The surfactant mass transfer and adsorption on the liquid gas interface gives rise to dynamic surface tension. As a result of the surfactant presence, the bubble departure diameters were smaller in CTAB solution compared to pure water. Furthermore, dynamic surface tension behavior of CTAB makes the bubble departure diameter a function of bubble Reynolds number (Re based on the orifice diameter and air flow rate). At low flow rates or low Re, the bubble departure diameters are smaller than those in water. As the air flow rate increases, the bubble departure diameters tend towards those in pure water. The authors gratefully acknowledge funding from AFOSR Thermal Science Program and AFRL DoD Supercomputing Resource Center for computing time and resources.

Dynamic surface tension of xylem sap at the air-water interface

2021 ◽  
Author(s):  
Reddy Prasanna Duggireddy ◽  
Eran Raveh ◽  
Gilboa Arye
Keyword(s):  
Surface Tension ◽  
Surface Activity ◽  
Pure Water ◽  
Xylem Sap ◽  
Dynamic Surface Tension ◽  
Bulk Solution ◽  
Diffusion Control ◽  
Dynamic Surface ◽  
Equilibrium Surface Tension ◽  
Air Interface

<p>The surface tension (ST) of xylem sap at the water-air interface is a crucial phenomenon, influencing many physiological events such as air seeding and embolism, by which xylem vessels become air-filled and cease to function. Refilling of embolized, may relies on sap’s surface activity at the interface. It is commonly assumed that the ST of xylem sap is equal to the ST of pure water (72 mN/m). However, xylem sap is a complex solution and consists of surface-active molecules that may adsorb and accumulate at the water-air interface and thereby reduce the ST of water as a function of their aqueous concentration. However, when a new water-air interface is formed, equilibrium ST is not reached instantaneously. Specifically, amphiphilic molecules are kinetically adsorbed and undergo orientation at the interface following diffusion from the bulk solution. Dynamic ST of xylem sap and liquid-solid interactions, describing the surface phenomena of the xylem of vascular plants is currently not fully understood. This is mainly due to a lack of quantitative knowledge on the rate and extent of dynamic and equilibrium ST of sap. In this regard, the main objective of this study is to quantify the dynamic and equilibrium ST of xylem sap as a function of their aqueous concentration. We extracted xylem sap from lemon trees and measured ST as a function of time using the pendant drop technique. The dynamic ST data were analyzed using empirical and diffusion-control mathematical models which adequately described the exponential-like decay of the ST as a function of time. The results showed reduced ST of water in the xylem sap, indicating significant surface activity, reaching equilibrium ST values as low as 42 mN/m. The rate of ST decay was higher in high sap concentration and reduced in diluted one. The results of dynamic and equilibrium ST and the corresponding model will be presented and their implications for xylem hydraulic functioning will be discussed.</p><p> </p><p>Keywords: Dynamic surface tension, Equilibrium surface tension, Diffusion, Xylem sap.</p><p> </p>

scholarly journals A pH-Responsive Foam Formulated with PAA/Gemini 12-2-12 Complexes

2021 ◽  
Vol 5 (3) ◽  
pp. 37
Author(s):  
Hernán Martinelli ◽  
Claudia Domínguez ◽  
Marcos Fernández Leyes ◽  
Sergio Moya ◽  
Hernán Ritacco
Keyword(s):  
Surface Tension ◽  
Dynamic Surface Tension ◽  
Foam Formation ◽  
Ph Responsive ◽  
Dynamic Surface ◽  
X Ray ◽  
Equilibrium Surface Tension ◽  
Potential Applications ◽  
The Stability ◽  
Air Interfaces

In the search for responsive complexes with potential applications in the formulation of smart dispersed systems such as foams, we hypothesized that a pH-responsive system could be formulated with polyacrylic acid (PAA) mixed with a cationic surfactant, Gemini 12-2-12 (G12). We studied PAA-G12 complexes at liquid–air interfaces by equilibrium and dynamic surface tension, surface rheology, and X-ray reflectometry (XRR). We found that complexes adsorb at the interfaces synergistically, lowering the equilibrium surface tension at surfactant concentrations well below the critical micelle concentration (cmc) of the surfactant. We studied the stability of foams formulated with the complexes as a function of pH. The foams respond reversibly to pH changes: at pH 3.5, they are very stable; at pH > 6, the complexes do not form foams at all. The data presented here demonstrate that foam formation and its pH responsiveness are due to interfacial dynamics.

An axisymmetric model for the analysis of dynamic surface tension

RSC Advances ◽  
2015 ◽  
Vol 5 (11) ◽  
pp. 7921-7931 ◽  
Author(s):  
S. I. Arias ◽  
J. R. Fernández ◽  
L. García-Rio ◽  
J. C. Mejuto ◽  
M. C. Muñiz ◽  
...  
Keyword(s):  
Surface Tension ◽  
Diffusion Length ◽  
Dynamic Surface Tension ◽  
Ionic Surfactants ◽  
Adsorption Behaviour ◽  
Dynamic Surface ◽  
Axisymmetric Model

An axisymmetric model accounts for dynamic surface tension of non-ionic surfactants under consideration of diffusive adsorption behaviour with a finite diffusion length.

Effect of plasticizer on the dynamic surface tension and the free volume of Eudragit systems

2002 ◽  
Vol 244 (1-2) ◽  
pp. 81-86 ◽  
Author(s):  
Romána Zelkó ◽  
Á Orbán ◽  
K Süvegh ◽  
Z Riedl ◽  
I Rácz
Keyword(s):  
Surface Tension ◽  
Free Volume ◽  
Dynamic Surface Tension ◽  
Dynamic Surface

Determination of albumin content in blood serum based on the results of dynamic surface tension

2021 ◽  
Vol 1 (6) ◽  
pp. 68-73
Author(s):  
M. S. Tsarkova ◽  
◽  
I. V. Milaeva ◽  
S. Yu. Zaytsev ◽  
◽  
...  
Keyword(s):  
Surface Tension ◽  
Blood Serum ◽  
Objective Assessment ◽  
Dynamic Surface Tension ◽  
The Body ◽  
Maximum Pressure ◽  
Dynamic Surface ◽  
Good Convergence ◽  
Albumin Content

The blood test allows you to give an objective assessment of the state of health of animals and timely identify changes occurring in the body. To assess the content of albumins in the blood serum, the method of measuring the dynamic surface tension on the VRA-1P device, which works according to the method of maximum pressure in the bubble, was used. Based on the results of the measurements, a mathematical model was proposed, and using the regression analysis method, formulas for determining the concentration of albumins were developed, which showed good convergence with other measurement methods.

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