scholarly journals Ultrasonically tuned surface tension and nano-film formation of aqueous ZnO nanofluids

2021 ◽  
Vol 72 ◽  
pp. 105424
Author(s):  
Elif Begum Elcioglu ◽  
S.M. Sohel Murshed
Keyword(s):  
Surface Tension ◽  
Film Formation ◽  
Zno Nanofluids

Surfactant convertase action is not essential for surfactant film formation

1997 ◽  
Vol 273 (5) ◽  
pp. L907-L912 ◽  
Author(s):  
N. J. Gross ◽  
R. Veldhuizen ◽  
F. Possmayer ◽  
R. Dhand
Keyword(s):  
Surface Tension ◽  
Film Formation ◽  
Surface Film ◽  
Lower Surface ◽  
Diisopropyl Fluorophosphate ◽  
Surfactant Film ◽  
Surface Active ◽  
Lower Surface Tension ◽  
Surface Balance

A serine-active enzyme, “surfactant convertase,” is required for the conversion of surfactant from the tubular myelin (TM) form to the small vesicular (SV) form. This transformation involves at least two steps, the conversion of TM to a surface-active film at the air-fluid interface and the reorientation of the film into the surface-inactive SV form; we asked if convertase was required for the first of these steps. Rat and mouse TMs were pretreated with diisopropyl fluorophosphate (DFP) to inactivate endogenous convertase activity or with vehicle and then were analyzed for their ability to lower surface tension in vitro as an index of the conversion of TM to a surface film. DFP pretreatment did not alter the ability of TM preparations to lower surface tension, as assessed by pulsating bubble, and it did not affect the behavior of TM in a surface balance. In an experiment designed to test the ability of TM to feed a surface film to exhaustion, TMs that had been pretreated with DFP or vehicle performed similarly. These experiments show that convertase activity is not required for the conversion of TM to a monolayer and suggest, instead, that convertase acts at a post surface film stage.

Film Formation and Flow Characteristics at the Inlet of a Starved Contact—Theoretical Study

1983 ◽  
Vol 105 (2) ◽  
pp. 178-185 ◽  
Author(s):  
D. Bonneau ◽  
J. Frene
Keyword(s):  
Surface Tension ◽  
Film Formation ◽  
Flow Characteristics ◽  
Integral Equation Method ◽  
Surface Velocity ◽  
Stress Distributions ◽  
New Interpretation ◽  
Inlet Zone ◽  
Hydrodynamic Effects ◽  
Effect Of Surface

The conditions of film formation are examined theoretically when starvation occurs. The analysis is for two-dimensional Newtonian flow and includes surface tension effects. Using an integral equation method, stream function solutions, velocity fields, pressure and shear stress distributions are calculated along and across the inlet zone of a sliding contact. The effect of surface tension and feeding thickness on the meniscus shape and on pressure buildup is studied in correlation with hydrodynamic effects. In all cases, pressure value lower than the gas pressure acting on the free boundary is found along the sliding surface. This depression value increases with an increase in viscosity or surface velocity. Owing to these results, a new interpretation of some published experimental data on starved contacts is proposed.

scholarly journals Effect of Marangoni Convection in a Droplet Containing Surfactant on Thin Film Shape

2021 ◽  
Vol 333 ◽  
pp. 03002
Author(s):  
Kazuki Matsuda ◽  
Tenshin Oyama ◽  
Hirotaka Ishizuka ◽  
Shuji Hironaka ◽  
Jun Fukai
Keyword(s):  
Thin Film ◽  
Surface Tension ◽  
Marangoni Convection ◽  
Printed Electronics ◽  
Film Formation ◽  
Droplet Diameter ◽  
Evaporation Process ◽  
Polystyrene Solution ◽  
Fluorescent Polymer ◽  
The Relationship

In printed electronics, uniform and solute film formation by the inkjet method is very important. This study aims to clarify the relationship between Marangoni convection generated by adding surfactant and thinning of solute film. First, four types of surfactants were added one by one to the anisole-polystyrene solution with varying concentrations, and then a little amount of fluorescent polymer was added as tracer to each solution. Next, each solution was dropped on a hydrophilic substrate with a droplet diameter of 80 micrometers using an inkjet method, and the flow in the evaporation process and the shape of the solute film after drying were observed. As a result, Marangoni convection occurred when any surfactant was added at a certain concentration or more, and the solute film after drying of the droplets to which two kinds of surfactants were added became thin and approached a uniform shape. In addition, the measurement of surface tension showed that the visualized flow is the Marangoni convection.

scholarly journals Reactive processing of formaldehyde and acetaldehyde in aqueous aerosol mimics: surface tension depression and secondary organic products

2011 ◽  
Vol 11 (7) ◽  
pp. 19477-19506 ◽  
Author(s):  
Z. Li ◽  
A. N. Schwier ◽  
N. Sareen ◽  
V. F. McNeill
Keyword(s):  
Surface Tension ◽  
Atmospheric Aerosols ◽  
Aldol Condensation ◽  
Film Formation ◽  
Pure Water ◽  
Additive Model ◽  
Single Species ◽  
Ionization Mass ◽  
Reactive Processing ◽  
Organic Products

Abstract. The reactive uptake of carbonyl-containing volatile organic compounds (cVOCs) by aqueous atmospheric aerosols is a likely source of particulate organic material. The aqueous-phase secondary organic products of some cVOCs are surface-active. Therefore, cVOC uptake can lead to organic film formation at the gas-aerosol interface and changes in aerosol surface tension. We examined the chemical reactions of two abundant cVOCs, formaldehyde and acetaldehyde, in water and aqueous ammonium sulfate (AS) solutions mimicking tropospheric aerosols. Secondary organic products were identified using Aerosol Chemical Ionization Mass Spectrometry (Aerosol-CIMS), and changes in surface tension were monitored using pendant drop tensiometry. Hemiacetal oligomers and aldol condensation products were identified using Aerosol-CIMS. A hemiacetal sulfate ester was tentatively identified in the formaldehyde-AS system. Acetaldehyde depresses surface tension to 65(±2) dyn cm−1 in pure water and 62(±1) dyn cm−1 in AS solutions. Surface tension depression by formaldehyde in pure water is negligible; in AS solutions, a 9 % reduction in surface tension is observed. Mixtures of these species were also studied in combination with methylglyoxal in order to evaluate the influence of cross-reactions on surface tension depression and product formation in these systems. We find that surface tension depression in the solutions containing mixed cVOCs exceeds that predicted by an additive model based on the single-species isotherms.

scholarly journals Reactive processing of formaldehyde and acetaldehyde in aqueous aerosol mimics: surface tension depression and secondary organic products

2011 ◽  
Vol 11 (22) ◽  
pp. 11617-11629 ◽  
Author(s):  
Z. Li ◽  
A. N. Schwier ◽  
N. Sareen ◽  
V. F. McNeill
Keyword(s):  
Surface Tension ◽  
Atmospheric Aerosols ◽  
Aldol Condensation ◽  
Film Formation ◽  
Pure Water ◽  
Additive Model ◽  
Single Species ◽  
Ionization Mass ◽  
Reactive Processing ◽  
Organic Products

Abstract. The reactive uptake of carbonyl-containing volatile organic compounds (cVOCs) by aqueous atmospheric aerosols is a likely source of particulate organic material. The aqueous-phase secondary organic products of some cVOCs are surface-active. Therefore, cVOC uptake can lead to organic film formation at the gas-aerosol interface and changes in aerosol surface tension. We examined the chemical reactions of two abundant cVOCs, formaldehyde and acetaldehyde, in water and aqueous ammonium sulfate (AS) solutions mimicking tropospheric aerosols. Secondary organic products were identified using Aerosol Chemical Ionization Mass Spectrometry (Aerosol-CIMS), and changes in surface tension were monitored using pendant drop tensiometry. Hemiacetal oligomers and aldol condensation products were identified using Aerosol-CIMS. Acetaldehyde depresses surface tension to 65(±2) dyn cm−1 in pure water (a 10% surface tension reduction from that of pure water) and 62(±1) dyn cm−1 in AS solutions (a 20.6% reduction from that of a 3.1 M AS solution). Surface tension depression by formaldehyde in pure water is negligible; in AS solutions, a 9% reduction in surface tension is observed. Mixtures of these species were also studied in combination with methylglyoxal in order to evaluate the influence of cross-reactions on surface tension depression and product formation in these systems. We find that surface tension depression in the solutions containing mixed cVOCs exceeds that predicted by an additive model based on the single-species isotherms.

scholarly journals Surfactant protein interactions with neutral and acidic phospholipid films

2001 ◽  
Vol 281 (1) ◽  
pp. L231-L242 ◽  
Author(s):  
Karina Rodriguez-Capote ◽  
Kaushik Nag ◽  
Samuel Schürch ◽  
Fred Possmayer
Keyword(s):  
Surface Tension ◽  
Surface Activity ◽  
Protein Interactions ◽  
Film Formation ◽  
Surfactant Protein ◽  
Surfactant Proteins ◽  
Specific Interactions ◽  
Equilibrium Surface ◽  
Equilibrium Surface Tension ◽  
Lipid Adsorption

The captive bubble tensiometer was employed to study interactions of phospholipid (PL) mixtures of dipalmitoylphosphatidylcholine (DPPC) and 1-palmitoyl-2-oleoyl- sn-glycero-3-phosphocholine (POPC) or 1-palmitoyl-2-oleoyl- sn-glycero-3-[phospho- rac-(1-glycerol)] (POPG) at 50 μg/ml with physiological levels of the surfactant protein (SP) A SP-B, and SP-C alone and in combination at 37°C. All surfactant proteins enhanced lipid adsorption to equilibrium surface tension (γ), with SP-C being most effective. Kinetics were consistent with the presence of two adsorption phases. Under the conditions employed, SP-A did not affect the rate of film formation in the presence of SP-B or SP-C. Little difference in γmin was observed between the acidic POPG and the neutral POPC systems with SP-B or SP-C with and without SP-A. However, γmax was lower with the acidic POPG system during dynamic, but not during quasi-static, cycling. Considerably lower compression ratios were required to generate low γminvalues with SP-B than SP-C. DPPC-POPG-SP-B was superior to the neutral POPC-SP-B system. Although SP-A had little effect on film formation with SP-B, surface activity during compression was enhanced with both PL systems. In the presence of SP-C, lower compression ratios were required with the acidic system, and with this mixture, SP-A addition adversely affected surface activity. The results suggest specific interactions between SP-B and phosphatidylglycerol, and between SP-B and SP-A. These observations are consistent with the presence of a surface-associated surfactant reservoir which is involved in generating low γ during film compression and lipid respreading during film expansion.

scholarly journals Removing Gas from a Closed-End Small Hole by Irradiating Acoustic Waves with Two Frequencies

Micromachines ◽  
2022 ◽  
Vol 13 (1) ◽  
pp. 109
Author(s):  
Yuta Matsumoto ◽  
Yuki Mizushima ◽  
Toshiyuki Sanada
Keyword(s):  
Surface Tension ◽  
Acoustic Waves ◽  
High Speed ◽  
Liquid Surface ◽  
Film Formation ◽  
Small Hole ◽  
Liquid Surface Tension ◽  
Gas Removal ◽  
Trapped Gases ◽  
Air Column

Filling microstructures in the air with liquid or removing trapped gases from a surface in a liquid are required in processes such as cleaning, bonding, and painting. However, it is difficult to deform the gas–liquid interface to fill a small hole with liquid when surface tension has closed one end. Therefore, it is necessary to have an efficient method of removing gas from closed-end holes in liquids. Here, we demonstrate the gas-removing method using acoustic waves from small holes. We observed gas column oscillation by changing the hole size, wettability, and liquid surface tension to clarify the mechanism. First, we found that combining two different frequencies enabled complete gas removal in water within 2 s. From high-speed observation, about half of the removal was dominated by droplet or film formation caused by oscillating the gas column. The other half was dominated by approaching and coalescing the divided gas column. We conclude that the natural frequency of both the air column and the bubbles inside the tube are important.

Application of ZnO Nanostructures in Improvement of Effective Surface Parameters in EOR Process

2013 ◽  
Vol 26 ◽  
pp. 9-16 ◽  
Author(s):  
Pouriya Esmaeilzadeh ◽  
Zahra Fakhroueian ◽  
Mohammad Nadafpour ◽  
Alireza Bahramian
Keyword(s):  
Surface Tension ◽  
Oil Recovery ◽  
Recovery Process ◽  
Contact Angles ◽  
Carbonate Reservoir ◽  
Reservoir Rock ◽  
Potential Applications ◽  
Wet Condition ◽  
Oil Water ◽  
Zno Nanofluids

ZnO nanosphericals and nanorods have interesting potential applications in various fields such as antibacterial and enhanced oil recovery process. In this work, it was shown that 30 ml of a water-based solution containing 3% of ZnO nanofluids could significantly change the wettability of a carbonate reservoir rock from a strongly oil-wet alter to a strongly water-wet condition, after 3 days aging of the rock at 70°C in the designed solution. Moreover, we have studied air-water and oil-water interfacial tensions of system containing nanofluids. Fluids included ZnO nanoparticles and quantum dots nanostructures (QDOTs ZnO) could effectively decrease the n-decane/water interfacial tension and air/water surface tension. So their efficiency is much higher in comparison with distilled water.The stabilization of various aqueous ZnO nanostructured in mixtures of NaCl, CaCl2, MgCl2and Na2SO4salts were investigated, and 50000-163000 ppm transparent and stable nanosalt fluids were fabricated. Wettability of an oil-wet carbonate rock aged for 3 days at 70°C in the designed ZnO nanosalt fluids was studied by measuring the contact angles. The results show a strong change in wettability of carbonate rocks from oil-wet to more water-wet condition. These nanosalt fluids performed an excellent trend of surface tension and IFT reduction in comparison with distilled water too.

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