Contact angle of air bubbles attached to an air-water surface in foam applications

Langmuir ◽  
1990 ◽  
Vol 6 (5) ◽  
pp. 995-1001 ◽  
Author(s):  
L. A. Lobo ◽  
A. Nikolov ◽  
A. Dimitrov ◽  
P. Kralchevski ◽  
D. T. Wasan
Keyword(s):  
Contact Angle ◽  
Water Surface ◽  
Air Bubbles

scholarly journals Does the kinorhynch have a hydrophobic body surface? Measurement of the wettability of a meiobenthic metazoan

2016 ◽  
Vol 3 (10) ◽  
pp. 160512 ◽  
Author(s):  
Daisuke Ishii ◽  
Hiroshi Yamasaki ◽  
Ryosuke Uozumi ◽  
Euichi Hirose
Keyword(s):  
Contact Angle ◽  
Body Surface ◽  
Water Surface ◽  
Aquatic Invertebrates ◽  
Anterior Part ◽  
The Body ◽  
Surface Measurement ◽  
Air Bubbles ◽  
Hydrophilic Surface

The body surface of aquatic invertebrates is generally thought to be hydrophilic to prevent the attachment of air bubbles. In contrast, some interstitial invertebrates, such as kinorhynchs and some crustaceans, have a hydrophobic body surface: they are often trapped at the water surface when the sediment in which they reside is mixed with air and water. Here, we directly measured the wettability of the body surface of the kinorhynch Echinoderes komatsui , using a microscopic contact angle meter. The intact body surface of live specimens was not hydrophobic, but the anterior part was less hydrophilic. Furthermore, washing with seawater significantly decreased the wettability of the body surface, but a hydrophilic surface was recovered after a 1 h incubation in seawater. We believe that the hydrophobic cuticle of the kinorhynch has a hydrophilic coat that is readily exfoliated by disturbance. Ultrastructural observations supported the presence of a mucus-like coating on the cuticle. Regulation of wettability is crucial to survival in shallow, fluctuating habitats for microscopic organisms and may also contribute to expansion of the dispersal range of these animals.

Research on Supporting Force of Several Models of Hydrophobic Plant Leaves

2012 ◽  
Vol 152-154 ◽  
pp. 1112-1117
Author(s):  
Qing Cheng Wang ◽  
Xiao Dong Yang ◽  
Guang Rui Shang ◽  
Zhuo Juan Yang ◽  
Guo Hua Cao ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Contact Angle ◽  
Water Surface ◽  
Mechanical Analysis ◽  
Contact Angles ◽  
Adhesive Tape ◽  
Plant Leaves ◽  
Instrument Measuring ◽  
Supporting Force ◽  
The Mathematical Model

In this paper, the leaves of 5 kinds of hydrophobic plants including lotus, canna, green poplar, grape and pumpkin were selected, whose contact angles were 150.6º, 135.5 º, 110.4 º, 101.3 º and 94.8 º respectively by contact angle instrument measuring. These plant leaves were adhered to rectangular box by double-sided adhesive tape, as experimental model.The maximum supporting force of these models on water surface were measured by analytical balance, and the supporting force increases as contact angle, the dimple pressed by the model on water surface can increase its supporting force. Through mechanical analysis, the mathematical model of the supporting force was established, the relationship between depth of dimple and contact angle was analyzed by the mathematical model.

Water–surface interactions and definitions for hydrophilicity, hydrophobicity and superhydrophobicity

2015 ◽  
Vol 87 (8) ◽  
pp. 759-765 ◽  
Author(s):  
Kock-Yee Law
Keyword(s):  
Contact Angle ◽  
Water Droplet ◽  
Water Surface ◽  
Adhesion Force ◽  
High Water ◽  
Residual Water ◽  
Basic Meaning ◽  
Main Driver ◽  
Receding Contact Angle ◽  
Hydrophilicity And Hydrophobicity

AbstractHydrophilicity and hydrophobicity are among the most important concepts in surface chemistry. Samuel and co-workers reported the measure of interactive forces between water and 20 different surfaces using the microbalance technique. Results showed that the wetting force correlates well to the advancing contact angle (θA), the larger the θA the lower the surface wettability. The adhesion force, measured when the water and surface first separates, correlates well to the receding contact angle (θR), the larger the θR the smaller the surface adhesion. The data also reveals that small residual water droplets are observed after the water droplet and the surface separate for surfaces with θR < 90°. This indicates high water affinity for these surfaces. No residual water droplet is observed for surfaces with θR > 90°. From the basic meaning of philicity-phobicity, θR∼90° is proposed as the new cut-off between hydrophilicity and hydrophobicity. The main driver for hydrophobicity is attributed to the high water surface tension. The merit of this proposed definition is discussed. Since wetting interaction becomes zero at θA ≥ 145°, surfaces with θR > 90° and θA ≥ 145° can further be defined as superhydrophobic. The extension of this approach to define oleophilicity/phobicity and superoleophobicity with hexadecane is discussed.

Fluid Dynamics of Hydrophilous Pollination in Ruppia (Widgeon Grass)

2016 ◽  
Author(s):  
Naga Musunuri ◽  
Ian Fischer ◽  
Pushpendra Singh ◽  
Daniel E. Bunker ◽  
Susan Pell
Keyword(s):  
Fluid Dynamics ◽  
Aquatic Plants ◽  
Water Surface ◽  
Pollen Dispersal ◽  
Pollen Grain ◽  
Air Bubbles ◽  
Ruppia Maritima ◽  
Two Dimensional ◽  
Brackish Waters ◽  
Hydrophilous Pollination

The aim of this work is to understand the physics underlying the mechanisms of two-dimensional aquatic pollen dispersal, known as hydrophily, that have evolved in several genera of aquatic plants, including Halodule, Halophila, Lepilaena, and Ruppia. We selected Ruppia maritima, which is native to salt and brackish waters circumglobally, for this study. We observed two mechanisms by which the pollen released from male inflorescences of Ruppia is adsorbed on a water surface: 1) inflorescences rise above the water surface and after they mature their pollen mass falls onto the surface as clumps and disperses as it comes in contact with the surface; 2) inflorescences remain below the surface and produce air bubbles which carry pollen mass to the surface where it disperses. In both cases dispersed pollen masses combined with others under the action of lateral capillary forces to form pollen rafts. The formation of porous pollen rafts increases the probability of pollination since the attractive capillary force on a pollen raft toward a stigma is much larger than on a single pollen grain. The presence of a trace amount of surfactant can disrupt the pollination process as the pollen is not captured or transported on the water surface.

Design and Supporting Force Experimental for the Bionic Water Strider Model

2013 ◽  
Vol 459 ◽  
pp. 543-546
Author(s):  
Qing Cheng Wang ◽  
Xiao Dong Yang ◽  
Zhuo Juan Yang
Keyword(s):  
Contact Angle ◽  
Experimental Determination ◽  
Experimental Measurement ◽  
Water Surface ◽  
Copper Wire ◽  
Copper Surface ◽  
Water Strider ◽  
Supporting Force

A bionic water strider model was designed and fabricated, which has four supporting legs with length of 52mm. Supporting legs were made of copper wire with diameter of 0.45mm, through superhydrophobic treatment for copper surface, whose contact angle is 154.3 °. By experimental measurement, the maximum supporting force of bionic water strider model on water surface is 28.5mN, which is 5.6 times its own weight. Adjusting supporting legs spacing, it can affect supporting force of the bionic water strider model on water surface. Experimental determination, the distance of the supporting legs should be larger than 8mm.

Irregular Bubble Entrainment Following Drop Impact on a Free Surface

2003 ◽  
Author(s):  
Yukio Tomita ◽  
Toshiyasu Kasai ◽  
Shinya Miura
Keyword(s):  
Free Surface ◽  
Impact Velocity ◽  
Water Surface ◽  
Drop Impact ◽  
Drop Diameter ◽  
Air Bubbles ◽  
Air Bubble ◽  
Bubble Entrainment ◽  
Irregular Case ◽  
The Impact

An air bubble is entrained by the impact of a drop on a water surface. Consequently sound is emitted. There are two categories of the bubble entrainment depending on the drop diameter dD and impact velocity Vimp. One is the regular entrainment where air bubbles are always pinched off, another is the irregular case where bubbles are trapped irregularly. In this paper we explore the mechanism of the irregular bubble entrainment and induced bubble sound.

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