Damping technique

Use of a vacuum cleaner or damping techniques to minimize dust generation. 

E Stress-strain measurements (measurement of initial slope in stress-strain diagram) Filament damping technique (Tokita, 1956 Van der Meer, 1970) magnetostrictive technique (Ballou and Silverman, 1944)... 

The variation of the loading curve shape with fibre orientation (angle a) is less regular in Im/s fracture tests and the identification of the point of fracture initiation from the load diagram was often problematic. Load-point displacements at fracture initiation in 1 m/s tests appear to be larger than in low rate tests. This apparent result is not unexpected, in view of the damping technique used in the impact tests which increases the compliance of the test system initially. 

The damping technique, originally suggested by K. Levenberg [Q. Appl. Math. 2 164 (1944)] and D.W. Marquardt [SIAM J. Appl. Math. 11, 463 (1963)], has been broadly implemented in numerical analysis, e.g. see J.E. Dennis and R.B. Schnabel, Numerical methods for unconstrained optimization and non-linear equations, Prentice-Hall, Englewood Cliffs, NJ (1983). 

During the iterative process, all fluctuations which - without the improvements introduced in this version of the code — rendered necessary the use of a damping technique are not any longer needed since the convergence is smooth until the final steps. 

There are many experimental techniques for studying interfacial relaxations of soluble adsorption layers. Except for the wave damping techniques, these methods are developed and used only by individual research groups. Up to now, no commercial set-up exists and therefore, relaxation experiments are not so wide spread. New developments in this field will probably increase the number of investigators studying the dynamic and mechanical properties of adsorption layers, since instruments are easy to construct and data handling is relatively simple. In this section, wave damping and other harmonic methods as well as transient relaxation techniques will be described. 

Hamill, O.P., Marty, A., Neher, E., Sakmann, B., and Sigworth, F.J. (1981) Improved patch-damp techniques for high-resolution current recording from cells and cell-free membrane patches. Pflugers Arch., 391 85-100. 

Fig. 1 Schematic diagram From membrane protein purification over reconstitution into dialysis vesides to patch damp technique (adapted from ref. 5).

Hectrophysiological measurements using the dip stick (6) and patch damp technique (7) were performed with three different preparations of proteoliposomes. Liposomes containing the entire CFqCFj (4), liposomes containing mainly CFg where most of CFj was removed by NaBr treatment (4) and liposomes containing subunit m which had been recovered from SDS gels (4,8). 

Fig. 1 Schematic diagram of the patch-damp technique [5] A heat-polished glass pipette (tip diameter in the order of l jim) is pressed against a clean membrane surface. Upon slight suction a high resistance seal (> 1 GO) forms between the tip of the pipette and the membrane. This high seal resistance and the small membrane area reduce the background noise in such a way, that it becomes possible to measure currents (< IpA) passing through a single ion channel protein. The mechanical stability of the seal between pipette and membrane allows the isolation of the membrane patch encircled by the pipette The withdrawal of the pipette in the attached configuration results in an inside-out patch.

There are various direct measurements of micellar solutions giving access to the dynamics rate constants - mainly based on disturbance of the equilibrium state by imposing various types of perturbations, such as stop flow, ultrasound, temperature and pressure jump [14,15[. This aspect is also not further elaborated here we focus instead on the impact of micellar kinetics on interfacial properties, to demonstrate that tensiometry and dilational rheology are suitable methods to probe the impact of micellar dynamics. The first work on this subject was published by Lucassen already in 1975 [16[ and he showed that the presence of micelles in the bulk have a measurable impact on the adsorption kinetics, and hence on the dilational elasticity, when measured by a longitudinal wave damping technique. Subsequent work demonstrated the effect of micellar dynamics on non-equilibrium interfacial properties [17-29]. The physical idea of the impact of micellar dynamics on the dynamic properties of interfacial layers can be easily understood from the scheme given in Figure 13.1. 

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