Tension transients

A.F. Huxley s 1957 Theory Further Structural Approaches Hugh Huxley s 1969 Theory Transient Mechanical Properties Velocity Transients Tension Transients... 

Parts a c of Fig. 5 show 3-D plots of the changes in the 14.5 nm layer line and equatorial reflections measured during an activation cycle at 100 ms time resolution, and are to be compared with the tension transient shown in Fig. 5 b. Clearly active tension production is associated with a large depression of the intensity of the 14.5 nm... 

Ranatunga, K. W., Coupland, M. E., and Mutungi, G. (2002). An asymmetry in the phosphate dependence of tension transients induced by length perturbation in mammalian (rabbit psoas) muscle fibres./. Physiol. 542, 899-910. 

The presence of liquid crystalline phases, their intermolecular structure and especially their state of dispersion definitely can affect interfacial tensions and interfacial tension transients (10), and may also influence other factors such as viscosity and the retention of surfactant during flow through a porous medium. 

The foregoing is an equilibrium analysis, yet some transient effects are probably important to film resilience. Rayleigh [182] noted that surface freshly formed by some insult to the film would have a greater than equilibrium surface tension (note Fig. 11-15). A recent analysis [222] of the effect of surface elasticity on foam stability relates the nonequilibrium surfactant surface coverage to the foam retention time or time for a bubble to pass through a wet foam. The adsorption process is important in a new means of obtaining a foam by supplying vapor phase surfactants [223]. 

The Imass Dynastat (283) is a mechanical spectrometer noted for its rapid response, stable electronics, and exact control over long periods of time. It is capable of making both transient experiments (creep and stress relaxation) and dynamic frequency sweeps with specimen geometries that include tension-compression, three-point flexure, and sandwich shear. The frequency range is 0.01—100 H2 (0.1—200 H2 optional), the temperature range is —150 to 250°C (extendable to 380°C), and the modulus range is 10" —10 Pa. 

In a foam where the films ate iaterconnected the related time-dependent Marangoni effect is mote relevant. A similar restoring force to expansion results because of transient decreases ia surface concentration (iacteases ia surface tension) caused by the finite rate of surfactant adsorption at the surface. 

Evidence suggests that there is a threshold tensile stress at which void nucleation occurs and spall fracture initiates. Materials subject to transient internal tensions can support tensile stresses significantly in excess of this threshold level, however. Such behavior is a consequence of kinetics and inertia associated with the nucleation and growth of voids during spall. A fairly large body of experimental and theoretical literature on spall phenomena exists and many aspects of the effect are reasonably well understood. Review articles on spall (Curran et al., 1977 Davision and Graham, 1979 Curran, 1982 Meyer and Aimone, 1983 Novikov, 1981) provide access to most of the literature on the subject. 

Impact of a thin plate on a sample of interest which is, in turn, backed by a lower impedance window material leads to an interaction of waves which will carry an interior planar region into tension. Spall will ensue if tension exceeds the transient strength of the test sample. A velocity or stress history monitored at the interface indicated in Fig. 8.4 may look as indicated in Fig. 8.5. The velocity (stress) pull-back or undershoot carries information concerning the ability of the test material to support transient tensile stress and, with appropriate interpretation, can provide a reasonable measure of the spall strength of the material. 

S. D. Ball. Comparison of transient interfacial tension behaviours of oiUalkaline systems as measured by the drop volume and spinning drop tensiometers. PhD thesis, Ottawa Univ, 1995. 

S. D. Ball, V. Homof, and G. H. Neale. Transient interfacial tension behavior between acidic oils and alkaline solutions. Chem Eng Com-mun, 147 145-156, May 1996. 

C. I. Chiwetelu, V. Homof, G. H. Neale, and A. E. George. Use of mixed surfactants to improve the transient interfacial tension behaviour of heavy oil/alkaline systems. Can J Chem Eng, 72(3) 534-540, June 1994. 

Choice of liquid Vapor pressure Surface tension Viscosity Chemical reactivity Intensity of collapse Transient cavitation threshold Transient cavitation threshold Primary or secondary sonochemistry... 

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