Air-liquid interfaces

FIG. 15-21 Continuous extraction of n-hiitylamine from kerosine into water. T = 1.23 ft, Z = 1.56 ft, no air-liquid interface, impellers centered, Vr/Ve X 1-57, residence time X 1.08 min. To convert feet to meters, multiply hy 0.3048 to convert inches to centimeters, multiply hy 2.54 and to convert horsepower to kilowatts, multiply hy 0.746. [Overcashiet Kingsley, and Olney, Am. Inst. Chem. Eng. J., 2, 529 (1.956), with permission.]... 

Consider the simple initial condition t = 0 where the sohd concentration (t),o is constant across the entire shiny domain ix < r < rb where / l and l b are, respectively, the radii of the shiny surface and the bowl. At a later time t > 0, three layers coexist the top clarified layer, a middle shiny layer, and a bottom sediment layer. The air-liquid interface remains stationaiy at radius / l, while the hqiiid-slurry interface with radius i expands radiaUy outward, with t with i given by ... 

There is a clinical need for non-natural, functional mimics of the lung surfactant (LS) proteins B and C (SP-B and SP-C), which could be used in a biomimetic LS replacement to treat respiratory distress syndrome (RDS) in premature infants [56]. An effective surfactant replacement must meet the following performance requirements (i) rapid adsorption to the air-liquid interface, (ii) re-spreadabihty... 

Fig. 26. The effect of shear on a range of enzymes with a stainless steel disc at a mean velocity gradient of 6490 s at 30 °C, in the presence of an air/liquid interface. Each data point in the figure is the mean value of 4 replicates and is given as a percentage of the control value [107]...

Formation of Langmuir films of spherical particles at the air-liquid interface [21,22,31,43,65-84]... 

In the first step, lipid model membranes have been generated (Fig. 15) on the air/liquid interface, on a glass micropipette (see Section VIII.A.1), and on an aperture that separates two cells filled with subphase (see Section VIII.A.2). Further, amphiphilic lipid molecules have been self-assembled in an aqueous medium surrounding unilamellar vesicles (see Section VIII.A.3). Subsequently, the S-layer protein of B. coagulans E38/vl, B. stearother-mophilus PV72/p2, or B. sphaericus CCM 2177 have been injected into the aqueous subphase (Fig. 15). As on solid supports, crystal growth of S-layer lattices on planar or vesicular lipid films is initiated simultaneously at many randomly distributed nucleation... 

Raman Microspectroscopy Study of Oscillatory Electrodeposition of Au at an Air/Liquid Interface... 

A stable foam is likely to have ingredients that are in a low energy state at the air-liquid interface. Substances that fit this description include proteins, emulsifiers some fats and fat components such as diglycerides monoglycerides and fatty acids. Food law uses the term emulsifier and stabiliser to cover the situation where the ingredient is stabilising an emulsion rather than helping to form it. 

FIAs can be based on steady-state intensity measurements without probe amplification, owing to the sensitivity of detection that is possible with fluorescence instrumentation, which exceeds that of spectrophotometers by two or three orders of magnitude. A sensitive fluorometer has been described for an estradiol assay(36) in which the limit of estradiol detection is 3 x KT11 M. Estradiol antibody labeled with rhodamine B is reacted with estradiol samples. Unreacted labeled antibody is removed with Sepharose-estradiol-casein beads, and the remaining fluorescence is directly proportional to the analyte concentration. The detection limit of rhodamine B on the same fluorometer is 5 x 1(T12 M. This instrument uses a 0.75 mW green helium-neon (HeNe) laser to irradiate the sample from above, at the air-liquid interface, to increase the light path and to decrease surface reflections. The sample compartment has a top-mounted photon trap, and a mirror mounted on the side of the sample compartment opposite the PMT to enhance detection. 

Yamashita F, Mathias NR, Kim K-J, Lee VHL (1996) Dipeptide transport properties of rabbit tracheal epithelial cell monolayers cultured at an air-liquid interface. PharmRes 15 979-983. 

Aufderheide M, Mohr U (1999) CULTEX—a new system and technique for the cultivation and exposure of cells at the air/liquid interface. Exp Toxicol Pathol 51 489-490... 

Bitterle E, Karg E, Schroeppel A, Kreyling WG, Tippe A, Ferron GA, Schmid O, Heyder J, Maier KL, Hofer T (2006) Dose-controlled exposure of A549 epithelial cells at the air-liquid interface to airborne ultrafine carbonaceous particles. Chemosphere 65 1784—1790... 

The fundamental physical chemistry of monolayers was worked out several decades ago by Langmuir, Harkins, Rideal, Adam, Schul-man, and others. In an excellent monograph, Gaines (38) has summarized the history and the state of knowledge up to 1966 of monolayers at air-liquid interfaces. Other good accounts of the subject can be found in several more general texts on surface chemistry (39-43). None, however, includes a discussion (or even a reference) to chirality in monolayers. 

Some further insight into the behaviour of salts at air-liquid interfaces may be obtained from a consideration of the electrification produced at such surfaces by solution of salts in the liquid, a point which will be considered in Oh. Vil. 

Instead of employing a cataphoretic method for determining the electrokinetic potentials at air-liquid interfaces, even more valuable information may be obtained by measurement of the E.M.F. of a cell of the type... 

The weak surfactant solution forms bubbles on agitation in the aqueous phase, which are stabilized as microscopic spheres from coalescing into large bubbles by the orientation of insoluble surfactant across the air/ liquid interface and by adhering to the hydrophobic surface created on the cement particle by the adsorbed surfactant. This is shown diagrammatically in Fig. 3.15 [16]. 

Fig. 11 Switching of a PS/PMMA brush is accomplished by immersion into various solvents. A polar solvent such as isobutanol brings PMMA to the air/liquid interface, while the PS collapses into the interior. The opposite occurs when the substrate is immersed into a nonpolar solvent such as cyclohexane. Upon immersion into a nonselective solvent, like THF, both components come to the air/liquid interface...

Transfer of the gas across the air-liquid interface (note that the formation of unique surface species may occur see below)... 

Table 8.5 shows the mass accommodation coefficients for S02, as well as for some other gases of tropospheric interest, on liquid water. It is seen that the uptake of most gases into liquid water is quite efficient. Interactions of gas molecules at the air-liquid interface may have additional implications other than the rate at which it is transferred into the aqueous... 

Importantly, no silver particulate film formation could be observed at the air/liquid interface, either in the chemical or in the electrochemical generation, in the absence of surfactants or under monolayers prepared from positively charged surfactants. 

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