Tension change

Smith [113] studied the adsorption of n-pentane on mercury, determining both the surface tension change and the ellipsometric film thickness as a function of the equilibrium pentane pressure. F could then be calculated from the Gibbs equation in the form of Eq. ni-106, and from t. The agreement was excellent. Ellipsometry has also been used to determine the surface compositions of solutions [114,115], as well polymer adsorption at the solution-air interface [116]. 

Zanker, Adam, Estimating Surface Tension Changes For Liquids, Hydrocarbon Processing, April 1980, p. 207. 

The caffeine contracture test involves exposing viable muscle fibers to incremental doses of caffeine from 0.5-32 mM, the concentration being increased every four min if no contraction develops. A positive caffeine contracture test is defined as the development of 0.2 g tension at 2 tiM caffeine, or > 7% tension change from baseline with 2 mM caffeine. 

Electric Effects. The science of electrocapillarity exists for over 100 years. When a liquid surface is electrically charged, its tension changes, and these changes can be followed quantitatively with the standard methods of measuring 7. It is tempting to apply the notions of electrocapillarity to solid surfaces, and a recent book162) is a particularly rich example. 

McQuain et al. (2003) undertook a detailed study on the effects of relative humidity and a direct comparison of fhe impacts DMSO vs. betaine in print buffer on the overall performance of quill pin printing. A video microscope was employed to visualize and track the drying behaviors of the various printing inks. A Cy5-labeled 466-bp dsDNA probe was used to monitor the printing process. Drop-drying behavior, bulk evaporation from the quill reservoir, surface tension changes, and spothng characteristics (spot diameter, spread, and number deposited) were examined at different RH levels. 

However, the advantage of the former over the latter method consists in that it makes it possible to choose the most convenient form and size of the body (platinum rod, ring, or plate) so as to enable the measurement to be carried out rapidly but without any detriment to its accuracy. The detachment method has found an application in the case of liquids whose surface tensions change with time. 

The magnitude of surface tension change will depend on the concentration and the solute added. In some cases, the surface tension (y) of the solution (such as NaCl) increases. The change in y may be small (per mole added) (as in the case of inorganic salts) or large (as in the case of such molecules as ethanol or other soap-like molecules) with the addition of solute (equal gram per liter) ... 

The surface tension y of water changes with the addition of organic or inorganic solutes at constant temperature and pressure (Defay et al., 1966 Chattoraj and Birdi, 1984 Birdi, 1989, 1997). The extent of surface tension change and the sign of the change are determined by the molecules involved (see Figure. 3.1). 

Thus, surface tension changes have been related to changes in the absolute potential differences across an electrode/electrolyte interface and to changes in the chemical potential of all the species, i.e., to changes in solution composition. Only one other quantity is missing, the surface excess. This can be easily introduced by recalling the definition of surface excess [Eq. (6.66)], i.e.,... 

To understand the beating of this electrochemical heart (Paik, 1996), it is necessary to think about the changes in potential that occur when the cell switches on and the Hg becomes a cathode to reduce 02. What surface tension changes will these potential changes bring about When the Hg is in contact with the Fe wire, and reducing 02, its potential moves to a more negative potential titan it had before, when... 

Norman and McIntyre (N4), 1960 Investigation of effect of surface tension changes caused by heat transfer on minimum flow rates required to ensure wetting of wetted-wall columns. 

Portalski (P3), 1960 Extensive study of film flow on vertical plates, with and without gas flow. Liquids included water, aqueous glycerol solutions, methanol. Data on effects of surface tension changes and surfactants, wave and surface velocities, increase in interfacial area by waves, etc. 

The surface entropy per unit area is given by the change in the surface tension with temperature. In order to determine the surface entropy one needs to measure how the surface tension changes with temperature. 

The simple prototype unit discussed here is capable of continuously monitoring a process stream with rapid response to surface tension changes, and accuracy within 1-2%. Initial investigations indicate that a commercial unit based on this design would be capable of data acquisition, alarm monitoring, and/or closed-loop control of a process variable in a laboratory, pilot plant or production scale installation. A commercial instrument based on the work done in this laboratory is being developed and marketed. 

The thermal effect is exploited to produce liquid pumping. For instance, a thermocapillary pump was constructed. The pumping method is based on surface-tension change due to local heating created by heaters fabricated on a Si-Pyrex chip. This method was used to pump reagents to perform successive PCR, gel electrophoresis, and detection [392,393],... 

Karaki H, Ikeda M, Urakawa N. 1967. Effects of external calcium and some metabolic inhibitors on barium-induced tension changes in guinea pig taenia coli. Jpn J Pharmacol 17 603-612. 

From strictly formalistic considerations, much larger surface tension changes are achieved in RP-HPLC than in HP-HIC separations of polypeptides and proteins, and these differences underpin the relative facility of these techniques to follow the same types of molecular binding events (and their perturbations) to the same level of physicochemical discrimination. Obviously, analogous approaches linking the interaction thermodynamics and the extrathermodynamic physicochemical properties or enthalpy-entropy compensation phenomena can be developed for the other major HPLC modes,... 

Shang T, Smith K A, Hatton T A. (2003) Photoresponsive surfactants exhibiting unusually large, reversible surface tension changes under varying illumination conditions. Langmuir... 

Viscosity and surface tension change with temperature, changing wet pickups Viscosity and surface tension change with component concentrations, changing wet pickups... 

Figure 3.73. Surface tension change caused by potassium salts (a) and the corresponding acids (b) m is the molality and the osmotic coefficient. (Redrawn from J.E.B. Randles. Phys. Chem. Uq. 7 (1977) 107.)...

The relations between the surface tensions and interfacial tension given in 9.VIII G apply strictly only to immiscible liquids when the liquids are partly miscible, the surface tensions change. For this case Antonoff proposed a rule which is generally understood (but perhaps not correctly) to mean that the interfacial tension between the two saturated liquid layers is equal, or very approximately equal, to the difference between the surface tensions of the two [mutually saturated] phases or solutions [against their common vapour] ... 

Second Case.—Whether the value of X which represents the initial composition of the liquid be less than or higher than y the vapor tension constantly decreases and approaches P the composition X of the liquid and the composition x of the vapor both vary in the same way and approach. When the vapor tension reaches the value P there is established a permanent regime of distillation the vapor tension changes no more the vapor distilled and the liquid not distilled conserve a constant composition f. This permanent regime is stable. 

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