Use Of Surface Tension Research Articles

An experimental study of rotating micromechanical liquid O-ring pressure seals

Shrinking macroscopic concepts of machinery to microscopic scales presentes several interesting challenges. One of these is the achievement of shaft pressure seals on rotating micromachines. This study investigates experimentally the feasibility of using surface tension to create a liquid pressure seal or O-ring. Based on the results of stationary and relative motion experiments conducted at macroscopic scales, the use of surface tension to create a liquid pressure seal or O-ring appears feasible. Although seal instabilities are found not to be an obvious problem and should be less important at microscales, further studies of possible seal instabilities at microscales are essential.

Aggregation of amphiphilic compounds in dimethyl sulfoxide: example of non-ionic alkyl–fluoroalkyl lipopeptides

The surface-active properties and association in dimethyl sulfoxide (DMSO) of two non-ionic alkyl–fluoroalkyl lipopeptides have been studied up to the limit of solubility (0.15–0.25) mol dm–3) by combined use of surface tension, 19F NMR, and small-angle neutron scattering (SANS) experiments. Various models of aggregation have been tested using least-squares procedures on both NMR and SANS data. The conclusion is a progressive and very limited aggregation of these surfactants in DMSO with a structure where the hydrophobic chains tend to gather together. Equilibrium constants for a multistep equilibrium are clearly weaker for the primary step of dimerization, thus showing the existence of weak cooperative solvophobic effects in higher aggregates.

The role of surface tension in the growth of strained quantum wire arraysa)

The critical radius of a strained quantum wire and the potential strain stabilization of quantum wire arrays has been investigated for the InxGa1−xAs/GaAs system. The critical radius of the quantum wire was calculated using an energy balance approach. The wire was found to be more stable than the corresponding two-dimensional quantum well structure. The use of surface tension as a stabilization force during the growth of strained quantum wire arrays is expected to have beneficial effects for arrays with greater than 7% InAs.

Liquid acquisition devices for superfluid helium transfer

To transfer superfluid helium (He II) in the milli- g or micro- g environment in orbit, it is necessary to provide a reasonably steady supply of liquid to the inlet of the pump in the supply dewar. To accomplish this without providing an artificial gravity through acceleration requires a liquid acquisition device. Fluid swirl and electrostatic devices have been proposed to orientate the fluid. However, the simplest mechanisms appear to be the use of surface tension or the thermomechanical effect. This paper examines four concepts for providing He II to the inlet of a thermomechanical pump. The devices are a distributed thermomechanical pump, a distributed pump with a main thermomechanical pump, a screened channel system and a vane/sponge combination. Calculations on the efficiency of these types of liquid acquisition devices are made using laboratory data from tests involving small scale devices where applicable. These calculations show that the latter two types of liquid acquisition devices are the most efficient. Questions as to the probability of cavitation and the effect of the residual shuttle acceleration on their operation remain to be answered, however.

Use of Surface Tension to Enable Observation of Submembranous Structures by Scanning Electron Microscopy

Use of Surface Tension to Enable Observation of Submembranous Structures by Scanning Electron Microscopy

A TECHNIQUE TO PREPARE ULTRA THIN CELLULOSE ACETATE-CELLULOSE LAMINATED MEMBRANE FOR THE REVERSE OSMOSIS

A new technique to prepare ultra thin laminate of CA on cellulose membrane (cellophane) for reverse osmosis was exploited by use of surface tension of water film formed on the swollen cellophane. Droplets of acetone or methyl acetate (conditioning solvent) were spread on the swollen cellophane, and CA solution with the same solvent was spread on it simultaneously. By this operation, the ultra thin and antipeeling laminate of CA was formed on cellophane. The mechanism of this lamination is explained as follows. Substitution of water in swollen cellophane by the foregoing solvent facilitates the anchoring of CA in the membrane to form thin laminate. The rejection of glucose by this laminate from its aqueous solution was about 60%.