Coalescence phenomenon

Figure 5. Coalescence phenomena a few hours after completion of the processing [(a) transmittance and (b) reflectance]. Multilamellar surfactant vesicle development phenomena twelve hours after the completion of the processing [(c) transmittance and (d) reflectance].

As a result of the small, but apparent single bond character of the triafulvene C3/C4 bond and the good stabilization of the transition state of the rotation established earlier, rotation around this bond should be lower in energy in comparison to simple ethylene derivatives183. In fact, 1H-NMR spectra of several types of asymmetrically substituted triafulvenes 219-224 proved to be temperature-dependent and showed reversible coalescence phenomena at definite temperatures diagnostic for internal rotation processes. These were characterized by the free enthalpy of activation AG at the coalescence point of appropriate substituent signals61. ... 

As shown by VT 1H NMR experiments, the two distinguishable species present in solutions of 40-43 were found to interconvert (coalescence phenomena) at higher temperatures. Provided that this isomerization is based... 

The experimental studies described in this chapter certainly led to a better understanding of the coalescence phenomena in concentrated emulsions. Despite the complexity and variety of the destruction scenarios, different methods for measuring the coalescence frequency, ty, have been proposed. It should be within the reach of future work to measure ty for a large variety of systems in order to establish a comparative stability scale. This is a necessary step to determine the microscopic parameters that control the activation energy Ea and the attempt frequency coo. 

The phenomenology described in the preceding section is general since it has been reproduced using different ionic surfactants, such as alkyl sulfonates or alkyl quaternary ammonia [11,12,16]. Villa et al. [17] have also investigated coalescence phenomena in W/OAV globules. They developed a capillary microscopy technique... 

In the 3,5-diethyl compound, slow ring inversion renders the CH2 protons of the ethyl groups nonequivalent, and appropriate coalescence phenomena are observed.360... 

For the pentathiepane 17 (Figure 17), 12 coalescence phenomena in the 3H and 13C NMR point to Gthermo(j. = lS.dkcalmoL1. The process was interpreted as a stereomutation on the pseudorotation circuit for twist-chair and chair <1997LA1517>. 

High porosity Higher flux (+) and higher coalescence phenomena (—)... 

From the area of thermal process engineering, the mass and heat transfer in stirred vessels and in bubble columns is treated. In the case of mass transfer in the gas/liquid system, coalescence phenomena are also dealt with in detail. The problem of simultaneous mass and heat transfer is discussed in association with film drying and in continuous electrophoresis. 

According to these premises, the relevance list must be formed with the following parameters Target quantity. kLa physical properties density p, viscosity i, diffusivity D and the coalescence parameters S of the liquid phase. Despite extensive research, coalescence phenomena have still not been clarified to such an extent as to permit explicit formulation of the coalescence parameters (see [22], section 4.10). Process parameters volume-related mixing power P/V, superficial velocity v of the gas and gravitational acceleration g. (The decision in favour of P/V and v instead of P/q and q/V was based on extensive research results obtained in the last three decades, see Section 10.4.1)... 

Figure 13 depicts a coalescence event that took place in 7 sec. Like other coalescence events in which new disclinations are produced, a 2tt disclination appeared at the position of the former boundary between the mesophase spherules. Frenkel (27) has pointed out that the time constant t for such coalescence phenomena is given approximately by... 

This measuring method is, due to its adaptability, very good for investigating coalescence phenomena in any physical system and is suitable for clarifying the chemical kinetics in mass transfer-limited reactions in gas/liquid systems (e.g. hydrogenations, oxidations, phosgenations, etc.) (see also [215]). 

Investigations of the interfacial area per unit volume a acquired a particular importance, only when the question was posed, to what extent was the influence of the coalescence phenomena on kbO due to its components kt and a. 

In this section only those coalescence phenomena are discussed, which occur in G/L systems. They are also much more strongly pronounced in this material system than in Lf L systems and have a significant effect particularly on the interfacial area and thus on mass transfer. 

Figure lb, d). A rapid sedimentation of insoluble coacervates onto the observation slide was the result of this instability (dark areas in Figure lb). At pH 4.2, vesicular coacervates were present and a number of flocculation/coalescence phenomena between coacervates were visible. As a general trend, BLG/AG dispersions at 2 1 Pr Ps ratio were less stable than at ratio 1 1. For instance, size distribution of coacervates was in the range 1-5 pim at ratio 1 1 and rather in the range 5-10 jxm at ratio 2 1. This may be explained by the better charge neutralization of coacervates in the latter case.14... 

Equation (170) may be derived by the method used by Behnken et al. (B4) in their study of particle growth processes. The primary difference is that one must account for fission of cells, a possibility not considered in the work cited. Similar equations, but not containing the growth terms, have been considered by Valentas (VI) in his study of droplet breakup and coalescence phenomena in agitated, two-phase systems. Note that if fission always results... 

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