Pinch-off mechanism

Figure 3 shows some topography of surfaces illustrating the pinch-off mechanism here T = 0.56 r , and = 64a. At time U, a layer of the sinusoid has relaxed away exposing a pair of terraces with relatively straight steps. At time U, a single pinch-off event has occurred and at time t, all relevant pinch-offs have been nucleated. By time u the layer has relaxed away. 

Figures. Snapshots of a surface obeying/-kinetics illustrating the pinch-off mechanism. T= 0.56 Tb, = 64a. toVo= 1.75x10 (no pinch-off), /,Vo= 2.62x10 (firstpinch-off),t2v0= 3.78x105 (steady-statepinch-off), tsVo = 5.24x10 (terrace dissolution virtually complete).

Illustration Satellite formation in capillary breakup. The distribution of drops produced upon disintegration of a thread at rest is a unique function of the viscosity ratio. Tjahjadi et al. (1992) showed through inspection of experiments and numerical simulations that up to 19 satellite drops between the two larger mother drops could be formed. The number of satellite drops decreased as the viscosity ratio was increased. In low-viscosity systems p < 0(0.1)] the breakup mechanism is self-repeating Every pinch-off results in the formation of a rounded surface and a conical one the conical surface then becomes bulbous and a neck forms near the end, which again pinches off and the process repeats (Fig. 21). There is excellent agreement between numerical simulations and the experimental results (Fig. 21). 

The signal transmission by the hormone-receptor complex can be actively inhibited via covalent modifications (e.g., protein phosphorylation) which deactivate the hormone-receptor complex. Another mechanism for termination of signaling pathways is the internalization of the hormone-receptor complex. During internalization a section of the membrane, together with the proteins bound to it, is pinched off and transported into the interior of the cell. There the receptor can be returned to the cell membrane or be degraded. The internalization can affect the free receptor as well as the hormone-receptor complex. 

Another mechanism of formation of the oil-in-water emulsion was observed. This involved the development of buds of oil at the oil-aqueous interface which were immediately pinched off to form an oil-in-water emulsion (See Figure 2E). 

A FIGURE 17-20 Model for dynamin-mediated pinching off of clathrin/AP-coated vesicles. After a vesicle bud forms, dynamin polymerizes over the neck. By a mechanism that is not well understood, dynamin-catalyzed hydrolysis of GTP leads to release of the vesicle from the donor membrane. Note that membrane proteins in the donor membrane are incorporated into vesicles by interacting with AP complexes in the coat. [Adapted from K. Takel et at, 1995, Nature 374 186.1... 

The physical basis for the lamella number is that a combination of capillary suction in the Plateau borders and the influence of mechanical shear cause the oil-phase distortion and pinch off into droplets. This result is in accord with the observations of emulsification and imbibition by Lobo et al. (50), French et al. (54), and Schramm and Novosad (37). The mechanical shear may come from several sources, including the flow... 

Snap-Off A mechanism for foam lamella generation in porous media. When gas enters and passes through a constriction in a pore, a capillary pressure gradient is created and causes liquid to flow toward the region of the constriction, where it accumulates and may cause the gas to pinch-off or snap-off to create a new gas bubble separated from the original gas by a liquid lamella. See also Lamella Division, Lamella Leave-Behind. 

Currently, several methods are available for the bulk isolation of purified plasma membrane fractions. Each of these plasma membrane isolation procedures involves three basic, successive steps tissue homogenization, subcellular fi-actionation, and assessment of the yield and/or purity of the isolated membrane fraction. During homogenization of brain tissue, nerve terminals are pinched off from their axonal connections and broken away from surrounding glial cell elements. Because nerve terminals are relatively resistant to mechanical stress, they can reseal to form synaptic bodies that are known as synaptosomes. Whittaker (4) and deRobertis (5) were the first to describe a method to purify these pinched-off nerve terminals. In their procedure, a crude... 

Figure 31 Suggested mechanism for the Hi - Imim transition. Undulations form in the hexagonal phase rods, which are being pinched at regular intervals, and this continues until the narrowest points along the rods are pinched off and discrete micelles form. (From Ref 164.)...

Rg. 11.16 A sketch of the mechanism of craze-matter production in a homo-polymer by a recurring interface-convolution process (Taylor-meniscus instability) (a) side view of the outline of the craze tip (b) top view of craze front (c) and (d) advance of the craze front by a completed period of interface convolution, with pinch-off (from Argon and Salama (1977) courtesy of Taylor and Francis). 

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