scholarly journals Coupled Effects of Spreading Solvent Molecules and Electrostatic Repulsions on the Behavior of PS-b-PAA Monolayers at the Air–Water Interface

Langmuir ◽  
2017 ◽  
Vol 33 (43) ◽  
pp. 12525-12534 ◽  
Author(s):  
Zineb Guennouni ◽  
Michel Goldmann ◽  
Marie-Claude Fauré ◽  
Philippe Fontaine ◽  
Patrick Perrin ◽  
...  
Keyword(s):  
Water Interface ◽  
Air Water Interface ◽  
Solvent Molecules ◽  
Electrostatic Repulsions

scholarly journals Surface behaviour of gangliosides and related glycosphingolipids

1978 ◽  
Vol 171 (3) ◽  
pp. 559-565 ◽  
Author(s):  
B Maggio ◽  
F A Cumar ◽  
R Caputto
Keyword(s):  
Dipole Moment ◽  
Surface Potential ◽  
Progressive Increase ◽  
Head Group ◽  
Polar Head Group ◽  
Water Interface ◽  
Collapse Pressure ◽  
Polar Head ◽  
Air Water Interface ◽  
Electrostatic Repulsions

1. The surface behaviour of six different gangliosides and eight chemically related glycosphingolipids was investigated in monolayers at the air-water interface. 2. Mono-, di-, tri and tetra-hexosylceramides had force-area isotherms showing similar limiting molecular areas on 145 mM-NaCl, pH 5.6. The increasing number of negatively charged sialosyl residues in mono-, di- and tri-sialogangliosides induced a progressive increase in the liquid-expanded character of the films and in the limiting area occupied per molecule, owing to electrostatic repulsions. When the ganglioside monolayers were spread on subphases at pH 1.2, the limiting area per molecule was similar to that found for neutral glycosphingolipids. 3. The monolayer collapse pressure at pH 5.6 increased with the number of uncharged carbohydrate units up to when the polar head group contained 3-4 residues. For gangliosides the collapse pressures were lower and decreased from mono- to tri-sialogangliosides. Ganglioside monolayers on subphases at pH 1.2 showed increases in their collapse pressure. 4. The glycosphingolipid monolayers studied had various surface in their collapse pressure. 4. The glycosphingolipid monolayers studied had various surface potentials according to the complexity of the polar head group of the lipid. Attempts to calculate the dipolar contributions to the surface potential from each carbohydrate residue suggest that the second and third sialosyl residues in di- and tri-sialogangliosides contributed with a vertical dipole moment opposite to that of the first sialosyl residue.

Sampling and analysis of the air-water interface with SEM and EDS of microlayers

1989 ◽  
Vol 47 ◽  
pp. 1004-1005
Author(s):  
Randall W. Smith ◽  
John Dash
Keyword(s):  
Heavy Metals ◽  
Surface Microlayer ◽  
Surface Films ◽  
Water Interface ◽  
Physical Processes ◽  
Infrared Spectroscopic Analysis ◽  
Eds Analysis ◽  
Air Water Interface ◽  
Significant Area ◽  
Bulk Chemical

The structure of the air-water interface forms a boundary layer that involves biological ,chemical geological and physical processes in its formation. Freshwater and sea surface microlayers form at the air-water interface and include a diverse assemblage of organic matter, detritus, microorganisms, plankton and heavy metals. The sampling of microlayers and the examination of components is presently a significant area of study because of the input of anthropogenic materials and their accumulation at the air-water interface. The neustonic organisms present in this environment may be sensitive to the toxic components of these inputs. Hardy reports that over 20 different methods have been developed for sampling of microlayers, primarily for bulk chemical analysis. We report here the examination of microlayer films for the documentation of structure and composition.Baier and Gucinski reported the use of Langmuir-Blogett films obtained on germanium prisms for infrared spectroscopic analysis (IR-ATR) of components. The sampling of microlayers has been done by collecting fi1ms on glass plates and teflon drums, We found that microlayers could be collected on 11 mm glass cover slips by pulling a Langmuir-Blogett film from a surface microlayer. Comparative collections were made on methylcel1ulose filter pads. The films could be air-dried or preserved in Lugol's Iodine Several slicks or surface films were sampled in September, 1987 in Chesapeake Bay, Maryland and in August, 1988 in Sequim Bay, Washington, For glass coverslips the films were air-dried, mounted on SEM pegs, ringed with colloidal silver, and sputter coated with Au-Pd, The Langmuir-Blogett film technique maintained the structure of the microlayer intact for examination, SEM observation and EDS analysis were then used to determine organisms and relative concentrations of heavy metals, using a Link AN 10000 EDS system with an ISI SS40 SEM unit. Typical heavy microlayer films are shown in Figure 3.

Temperature Dependence of the Air/Water Interface Revealed by Polarization Sensitive Sum-Frequency Generation Spectroscopy

2018 ◽  
Author(s):  
Daniel R. Moberg ◽  
Shelby C. Straight ◽  
Francesco Paesani
Keyword(s):  
Temperature Dependence ◽  
Low Frequency ◽  
Potential Energy Function ◽  
Md Simulations ◽  
Sum Frequency Generation ◽  
Water Molecules ◽  
Water Interface ◽  
Sum Frequency ◽  
Air Water Interface ◽  
Frequency Generation

<div> <div> <div> <p>The temperature dependence of the vibrational sum-frequency generation (vSFG) spectra of the the air/water interface is investigated using many-body molecular dynamics (MB-MD) simulations performed with the MB-pol potential energy function. The total vSFG spectra calculated for different polarization combinations are then analyzed in terms of molecular auto-correlation and cross-correlation contributions. To provide molecular-level insights into interfacial hydrogen-bonding topologies, which give rise to specific spectroscopic features, the vSFG spectra are further investigated by separating contributions associated with water molecules donating 0, 1, or 2 hydrogen bonds to neighboring water molecules. This analysis suggests that the low frequency shoulder of the free OH peak which appears at ∼3600 cm−1 is primarily due to intermolecular couplings between both singly and doubly hydrogen-bonded molecules. </p> </div> </div> </div>

Sign in / Sign up

Export Citation Format

Share Document