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.

The Effect of Interfacial Waves on the Transition to Slug Flow

1994 ◽  
Vol 116 (3) ◽  
pp. 583-591 ◽  
Author(s):  
Eugene Kordyban ◽  
Abdul Hakim Okleh
Keyword(s):  
Surface Tension ◽  
Slug Flow ◽  
Lower Surface ◽  
Phase Flow ◽  
Closed Channel ◽  
Two Phase ◽  
Wave Growth ◽  
Surface Active Agents ◽  
Surface Active ◽  
Lower Surface Tension

It has been proposed by the authors that the transition to slug flow depends on the growth of waves in the two-phase flow and thus may predict if the laws of wave growth in closed channel are known. In this work, this proposition is tested by examining the highest waves and the transition to slug flow for air and water, air and water with surface tension reduced by addition of surface-active agents, air and water with increased viscosity by addition of corn syrup and air and ethanol. In each case it is found that the predicted transition to slug flow agrees well with experimental data. Neither a lower surface tension nor a higher viscosity has any effect on the transition to slug flow, but the use of surface active agents reduces the wave growth rate and causes the transition to slug flow to shift to higher gas velocities.

scholarly journals Investigation about wetting ability (surface tension) of water used for preparation of pesticide solutions

2021 ◽  
Vol 117 (3) ◽  
pp. 1
Author(s):  
Donyo Hristov GANCHEV
Keyword(s):  
Surface Tension ◽  
Water Source ◽  
Lower Surface ◽  
Flow Rates ◽  
Wetting Ability ◽  
Lower Resistance ◽  
Wax Content ◽  
Lower Surface Tension ◽  
Plant Surfaces

<p class="042abstractstekst">The investigation about surface tension of water used for preparation of pesticide solutions reveals it is quite diverse and changeable without any logical correlation towards location, time, and type of water source. Moreover, spraying with solutions with lower surface tension give bigger flow rates due to the lower resistance of fluid to the nozzles. The conducted trials show that plant surfaces with more rough texture require to be sprayed with pesticide solutions with lower surface tension. The wax content of the surfaces has no significant impact on surface tension requirement.</p><p> </p>

Experiments on the breakup of drop-impact crowns by Marangoni holes

2018 ◽  
Vol 844 ◽  
pp. 162-186 ◽  
Author(s):  
Abdulrahman B. Aljedaani ◽  
Chunliang Wang ◽  
Aditya Jetly ◽  
S. T. Thoroddsen
Keyword(s):  
Surface Tension ◽  
Lower Surface ◽  
High Viscosity ◽  
Solid Substrate ◽  
Immiscible Liquid ◽  
Hole Formation ◽  
Low Viscosity ◽  
Stress Changes ◽  
Lower Surface Tension ◽  
The Impact

We investigate experimentally the breakup of the Edgerton crown due to Marangoni instability when a highly viscous drop impacts on a thin film of lower-viscosity liquid, which also has different surface tension than the drop liquid. The presence of this low-viscosity film modifies the boundary condition, giving effective slip to the drop along the solid substrate. This allows the high-viscosity drop to form a regular bowl-shaped crown, which rises vertically away from the solid and subsequently breaks up through the formation of a multitude of Marangoni holes. Previous experiments have proposed that the breakup of the crown results from a spray of fine droplets ejected from the thin low-viscosity film on the solid, e.g. Thoroddsen et al. (J. Fluid Mech., vol. 557, 2006, pp. 63–72). These droplets can hit the inner side of the crown forming spots with lower surface tension, which drives a thinning patch leading to the hole formation. We test the validity of this assumption with close-up imaging to identify individual spray droplets, to show how they hit the crown and their lower surface tension drive the hole formation. The experiments indicate that every Marangoni-driven patch/hole is promoted by the impact of such a microdroplet. Surprisingly, in experiments with pools of higher surface tension, we also see hole formation. Here the Marangoni stress changes direction and the hole formation looks qualitatively different, with holes and ruptures forming in a repeatable fashion at the centre of each spray droplet impact. Impacts onto films of the same liquid, or onto an immiscible liquid, do not in general form holes. We furthermore characterize the effects of drop viscosity and substrate-film thickness on the overall evolution of the crown. We also measure the three characteristic velocities associated with the hole formation: i.e. the Marangoni-driven growth of the thinning patches, the rupture speed of the resulting thin films inside these patches and finally the growth rate of the fully formed holes in the crown wall.

Cosurfactants Lower Surface Tension of the Diglyceride/Water Interface:  A Molecular Dynamics Study

Langmuir ◽  
1996 ◽  
Vol 12 (10) ◽  
pp. 2570-2579 ◽  
Author(s):  
Aldert R. van Buuren ◽  
D. Peter Tieleman ◽  
Jacob de Vlieg ◽  
Herman J. C. Berendsen
Keyword(s):  
Molecular Dynamics ◽  
Surface Tension ◽  
Lower Surface ◽  
Water Interface ◽  
Lower Surface Tension

Film forming behaviour of oil soluble polyalkylene glycols

2015 ◽  
Vol 67 (2) ◽  
pp. 133-138 ◽  
Author(s):  
Martin Greaves ◽  
Ksenija Topolovec Miklozic
Keyword(s):  
Contact Pressure ◽  
Film Formation ◽  
Surface Film ◽  
Electrical Contact ◽  
Electrical Contact Resistance ◽  
Content Type ◽  
Film Forming ◽  
Specific Contact ◽  
Surface Active ◽  
Forming Behaviour

Purpose – The purpose of this paper was to examine the film-forming behaviour of simple compositions of polyalphaolefin (PAO) containing an oil-soluble polyalkylene glycol (OSP) alone, a zinc dialkyl dithiophosphate (ZDDP) alone and then combinations of an OSP and ZDDP. Design/methodology/approach – A Mini-Traction Machine with Spacer Layer Imaging technology was used to evaluate friction and film formation under a specific contact pressure, temperature and slide-to-roll ratio. Electrical contact resistance measurements were used to follow surface film formation. Findings – The inclusion of an OSP to a PAO showed evidence of friction-reducing behaviour with low friction values over the rubbing cycle but no significant tribo-film build up. When a ZDDP (1 per cent) is added to the PAO, a thick tribo-film forms of about 100 nm. Addition of an OSP (10 per cent) shows this film still forms despite the OSP being a polar and surface-active additive. Research limitations/implications – The study was conducted under a narrow range of test conditions (e.g. temperature and contact pressure), and future work will focus on friction and film formation across a broader set of conditions. Practical implications – Despite OSPs being polar and surface-active, they do not interfere with the ZDDP in forming an anti-wear film in a PAO and, therefore, their inherent properties of good deposit control could enhance the performance of modern lubricants. Originality/value – OSPs offer promising benefits as friction reducers in PAOs. The research also suggests that OSPs do not negate the formation of ZDDP anti-wear tribo-films when in combination in a PAO.

Surface tension influences cell shape and phagocytosis in alveolar macrophages

2006 ◽  
Vol 291 (4) ◽  
pp. L572-L579 ◽  
Author(s):  
Hiroko Akei ◽  
Jeffrey A. Whitsett ◽  
Michelle Buroker ◽  
Takafumi Ninomiya ◽  
Haruyuki Tatsumi ◽  
...  
Keyword(s):  
Surface Tension ◽  
Alveolar Macrophages ◽  
Surfactant Protein ◽  
Surfactant Film ◽  
Fluorescent Microbeads ◽  
Alveolar Surface ◽  
Mouse Macrophage Cell Line ◽  
Effect Of Surface

The effect of surface tension on alveolar macrophage shape and phagocytosis was assessed in vivo and in vitro. Surface tension was regulated in vivo by conditionally expressing surfactant protein (SP)-B in Sftpb−/−mice. Increased surface tension and respiratory distress were produced by depletion of SP-B and were readily reversed by repletion of SP-B in vivo. Electron microscopy was used to demonstrate that alveolar macrophages were usually located beneath the surfactant film on the alveolar surfaces. Reduction of SP-B increased surface tension and resulted in flattening of alveolar macrophages on epithelial surfaces in vivo. Phagocytosis of intratracheally injected fluorescent microbeads by alveolar macrophages was decreased during SP-B deficiency and was restored by repletion of SP-B in vivo. Incubation of MH-S cells, a mouse macrophage cell line, with inactive surfactant caused cell flattening and decreased phagocytosis in vitro, findings that were reversed by the addition of sheep surfactant or phospholipid containing SP-B. SP-B controls surface tension by forming a surfactant phospholipid film that regulates shape and nonspecific phagocytic activity of alveolar macrophages on the alveolar surface.

Dipalmitoyl lecithin: studies on surface properties

1965 ◽  
Vol 20 (4) ◽  
pp. 779-781 ◽  
Author(s):  
Marian C. Kuenzig ◽  
Robert W. Hamilton ◽  
Leonard F. Peltier
Keyword(s):  
Surface Tension ◽  
Pulmonary Surfactant ◽  
Surface Film ◽  
Ethanol Solution ◽  
Original Surface ◽  
Dipalmitoyl Lecithin ◽  
Minimum Surface Tension ◽  
Humidified Air ◽  
Surface Balance ◽  
Normal Lungs

A preparation of synthetic dipalmitoyl lecithin has been devised whose activity on a Wilhelmy surface balance is similar to that of extracts from normal lungs. An ethanol solution of lecithin is precipitated with albumin, and a drop of the suspension containing approximately 0.04 mg lecithin is spread on the surface of 0.9% NaCl in the trough of the balance. This preparation appears to be insensitive to oxidation and when run under humidified air gives reproducible results. It has a low minimum surface tension (5—10 dynes/cm) when compressed to 20% of the original surface area and exhibits considerable hysteresis on re-expansion. Addition of certain lipids to the surface film produces changes similar to those caused by addition of these lipids to cat lung extracts. surface tension; surface activity; pulmonary surfactant Submitted on September 8, 1964

Surfactant inactivation by hyperventilation: conservation by end-expiratory pressure

1975 ◽  
Vol 38 (3) ◽  
pp. 461-466 ◽  
Author(s):  
I. Wyszogrodski ◽  
K. Kyei-Aboagye ◽  
H. W. Taeusch ◽  
M. E. Avery
Keyword(s):  
Surface Tension ◽  
Specific Activity ◽  
Surface Film ◽  
Active Material ◽  
Positive End Expiratory Pressure ◽  
Elastic Recoil ◽  
Minimum Surface Tension ◽  
Surface Active ◽  
Film Balance ◽  
Surface Active Material

Hyperventilation, defined as repeated hyperinflations, for three hours in open-chested anesthetized cats increased elastic recoil and elevated minimum surface tension of lung extracts as measured on a surface film balance. Equivalent hyperventilation from an elevated lung volume did not alter the pressure-volume relationships. When a mixture of [3H]glycerol and [14C]palmitate had been injected 17 h before the three hour period of phyerventilation, an increase in the ratio of specific activity in wash to tissue lecithin occurred in the hyperventilated cats compared to controls. These findings suggest that hyperventilation promotes release of surface active material from tissue to alveolus, but the released material is inactivated. The application of 2.5 cmH2O positive end-expiratory pressure prevented the adverse effects of hyperventilation. The same increase in wash to tissue lecithin occurred during this study; since the material was appropriately surface active, we conclude that the positive end-expiratory pressure prevented its inactivation.

scholarly journals Effect of an Alcohol-Based Caries Detector on the Surface Tension of Sodium Hypochlorite Preparations

2015 ◽  
Vol 26 (1) ◽  
pp. 66-68 ◽  
Author(s):  
Giampiero Rossi-Fedele ◽  
Andrea R. Guastalli
Keyword(s):  
Surface Tension ◽  
Sodium Hypochlorite ◽  
Surface Active Agent ◽  
Active Agent ◽  
Pendant Drop ◽  
Root Canal Irrigants ◽  
Significant Difference ◽  
Surface Active ◽  
Pendant Drop Method

The purpose of this study was to evaluate the effect of an alcohol-based caries detector (Kurakay) on the surface tension of a conventional sodium hypochlorite (NaOCl) preparation, and a product containing a surface-active agent (Chlor-XTRA). The surface tensions of the following solutions were tested: NaOCl, a mixture of NaOCl and Kurakay 9:1 w/w, Chlor-XTRA, a mixture of Chlor-XTRA and Kurakay 9:1 w/w. Ten measurements per test solution were made at 20 C, using an optical method called the "Pendant drop method", with a commercially available apparatus. The addition of Kurakay reduced the surface tension for NaOCl (p<0.05) whilst no significant difference was detected for Chlor-XTRA (p>0.05). Statistically significant differences between the NaOCl and Chlor-XTRA groups were found (p<0.05). The addition of an alcohol-based caries detector resulted in a reduction of the original surface tension values for NaOCl only. Taking into account the fact that mixtures of NaOCl and Kurakay have been used to assess the penetration of root canal irrigants in vitro, the related changes in surface tension are a possible source of bias.

Sign in / Sign up

Export Citation Format

Share Document