Ultrasound disturbance

Then, the weld depths penetration are controlled in a pulse-echo configuration because the weld bead (of width 2 mm) disturbs the detection when the pump and the probe beams are shifted of 2.2 mm. The results are presented in figure 8 (identical experimental parameters as in figure 7). The slow propagation velocities for gold-nickel alloy involve that the thermal component does not overlap the ultrasonic components, in particular for the echo due to the interaction with a lack of weld penetration. The acoustic response (V shape) is still well observed both for the slot of height 1.7 mm and for a weld depth penetration of 0.8 mm (lack of weld penetration of 1.7 mm), even with the weld bead. This is hopeful with regard to the difficulties encountered by conventional ultrasound in the case of the weld depths penetration. 

Dispersion Technology DT-1200 combines the DT-100 with the DT-200 to give both size and zeta potential. Ultrasound induces a motion of particles relative to the liquid. This motion disturbs the double layer shifting a screening cloud of counter-ions. This displacement creates a dipole moment the sum of which creates an electric field that is measured by two electrode sensors. This field depends upon the value of the zeta potential which can be calculated using the appropriate theory. 

In contrast, the disturbance caused by the ultrasound oscillator induces characteristic oscillations within the given liquid column, corresponding to its geometry and its physical characteristics. Expression defining a number of possible values of the liquid column oscillation frequencies is obtained as a solution of the corresponding rate potential function for the standing wave formed on the meniscus surface, in the form [1-2] ... 

The term active mixer or active microimxef refers to a microfluidic device in which species mixing is enhanced by the application of some form of external energy disturbance. Typically, this disturbance is generated either by moving components within the micromixer itself, e.g. magnetically-actuated stirrers, or by the application of an external force field, e. g. pressure, ultrasound, acoustic, electrohydrodynamic, electrokinetic, dielectrophoretic, magneto-hydrodynamic, thermal, and so forth [1]. 

The placental barrier in rats can be disturbed by fetal hypertension that opens paracellular pathways through the syncytial layer of the trophoblast (Kertschanska, Stulcova et al. 2000). On the other hand, Hua and eoworkers (Hua, Zhu et al. 2009) showed that contrast-enhanced ultrasound does not increase the permeability of placenta to macromolecules larger than lanthanum or albumine. 

The control of surface functionality by proper selection of the composition of the LB films and/or the self-assembling (amphiphatic) molecular systems can mimic many functions of a biologically active membrane. An informative comparison is that between inverted erythrocyte ghosts (Dinno et al., 1991 Matthews et al., 1993) and their synthetic mimics when environmental stresses are imposed on both systems. These model systems can assist in mechanistic studies to understand the functional alterations that result from ultrasound, EM fields, and UV radiation. The behavior of carrier molecules and receptor site functionality must be mimicked properly along with simulating disturbances in the proton motive force (PMF) of viable cells. Use of ion/electron transport ionomers in membrane-catalyst preparations is beneficial for programs such as electro-enzymatic synthesis and metabolic pathway emulation (Fisher et al., 2000 Chen et al., 2004). Development of new membranes used in artificial organs and advances in micelle reaction systems have resulted from these efforts. 

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. 

---