Lamellae profiles

Fig. 32 Changes in the lamella profiles viewed along the x-axis, during melting at 380 K a at 0.0 ns, b at 0.128 ns, c at 0.64 ns. We can see that the tapered growth fronts retreat at 380 K maintaining the tapered shape at the edges...

At equilibrium and in the flat portion of a thin-liquid film, the disjoining pressure, O, equals the capillary pressure. Pc- Therefore, measurements of the capillary pressure are used to evaluate fl. Two methods can be utilized to determine Pc, i.e. direct pressure measurements and lamella-profile measurements. In the latter case, the mean curvature of the meniscus is obtained and Pc is determined by using Laplace s equation. 

Figure 21.8. Schematic of the geometric constraints used to obtain capillary pressure measurements via the lamella profile (from ref. (11))...

Figure 5.21. Composition profile across the primary7 secondary lamellae boundary shown in Figure 5.20 (line X-X). (Reproduced with permission of Zieba et al. 1997.)...

A model of lamellae formation In stretched networks is proposed. Approximately one-half of the chains do not fold. Formation of such lamellae Is accompanied by declining stress. Highly folded systems (high crystallinity), however, can cause a stress Increase. In the calculations crosslinks are assigned to their most probable positions through the use of a characteristic vector. A contingent of amorphous chains Is also Included. The calculations suggest that the concept of fibrillar-lamellar transformations may be unnecessary to explain observed stress-temperature profiles In some cases. 

This may be what happens in polyethylene networks (1 ). A transformation from one morphology to another is therefore not at all required. The observed stress profile may be indicative of nothing more than a normal progression of lamellar growth whereby more and more folds are incorporated by the growing lamellae. 

A comparison of the calculated relative peak heights using the very simplified electron density profiles of Figs. 23b and 23d with the SAXS pattern of the sample, Fig. 24, unequivocally indicates the presence of the non-centrosysmmetric lamellae structure depicted in Fig. 23a. In agreement with SCMF calculations [90], the centrosymmetric two-way arrangement (Fig. 23c) of A-B-C-A-C-B pattern was not observed. 

FIGURE 1-7 A lipofiiscin granule from a cortical neuron shows membrane-bound lipid (dense) and a soluble component (gray). The denser component is lamellated. The lamellae appear as paracrystalline arrays of tubular profiles when sectioned transversely (arrow). The granule is surrounded by a single-unit membrane. Free ribosomes also can be seen. X96,000. 

The main changes induced by an osmotic treatment affecting the mechanical behavior of plant tissues are loss of cellular turgor, alteration of middle lamella (Alzamora et al., 1997), alteration of cell wall resistance, establishment of water and solute concentration profiles (Salvatori et al.,... 

Fig. 7 Freeze-fracture images of hydrogenosomes from T. foetus, a Fractured cell showing a prominent Golgi (G) with several lamellae and fenestrae, as well profiles of endoplasmic reticulum (ER) in close proximity (arrows) with hydrogenosomes (H). Bar = 100 nm. b Hydrogenosomes from an isolated fraction observed by freeze-fracture. Note the clusters of intramembranous particles forming rosettes (arrow). The peripheral vesicle is smooth and does not present clusters of particles or rosettes. Bar = 50 nm. (From Benchimol et al. 2001). c Two freeze-fractured hydrogenosomes exhibiting different fracture planes (arrows). Bar = 100 nm. (From Benchimol et al. 1996a)...

Figure 1.6. Fracture surface of sintered PTFE showing a nearly hexagonal crystal viewed with its c-axis perpendicular to the plane of the micrograph. This crystal grew upon and perpendicular to a primary lamella, which is seen side-on and shows the curved edge profile associated with growth by nucleation and thickening. Magnification = 75,200, Scale bar = 0.5 pm.

Fig. 2.54 Neutron reflectivity profile for a symmetric PS-dPMMA diblock (Mw 30 kg moP1) as a function of incident wavevector (Russell 1990). The inset shows the scattering length density (b/V, the neutron scattering length per unit volume) profile normal to the film surface that was used to calculate the reflectivity profile shown as the solid line, This is typical of a block copolymer film containing a multilayer stack, with lamellae parallel to the surface.

The domain spacing obtained by Hamley et al. (1997a) and Ryan et al. (1995) increased discontinuously upon crystallization, as indicated by the shift of the principal peak position, q, to lower q, as apparent in Fig. 5.3. Here q = AnsinOIX where 20 is the scattering angle and X is the X-ray wavelength. The SAXS profiles from the crystallized diblocks were shown to correspond to the sum of scattering from block copolymer lamellae, with up to four orders of reflection, plus a broad... 

Generally, lipids forming lamellar phase by themselves, form lamellar lipoplexes in most of these cases, lipids forming Hn phase by themselves tend to form Hn phase lipoplexes. Notable exceptions to this rule are the lipids forming cubic phase. Their lipoplexes do not retain the cubic symmetry and form either lamellar or inverted hexagonal phase [20, 24], The lamellar repeat period of the lipoplexes is typically 1.5 nm higher than that of the pure lipid phases, as a result of DNA intercalation between the lipid bilayers. In addition to the sharp lamellar reflections, a low-intensity diffuse peak is also present in the diffraction patterns (Fig. 23a) [81]. This peak has been ascribed to the in-plane positional correlation of the DNA strands arranged between the lipid lamellae [19, 63, 64, 82], Its position is dependent on the lipid-DNA ratio. The presence of DNA between the bilayers has been verified by the electron density profiles of the lipoplexes [16, 62-64] (Fig. 23b). 

Hence, the main information is that the in-line concentration profiles confirm the uniform multi-lamellae formation over a favorable large range of flow rates given already by photographic flow-pattern imaging (see Multi-lamination patterns) [20],... 

The second major difference of the flow patterns of the triangular to the rectangular mixers that more complex concentration profiles are found which have more peaks than the number of generated lamellae [20], This becomes evident at volume flows > 200 ml h-1. 

In addition, dynamic studies were performed including moving fluids. Generally, similar results were obtained [140], Different from the stationary case, the width of the inner lamellae is decreased relative to the outer layers owing to the parabolic flow profile. 

For increased flow rates, however, the CFD simulations show more and more deviations from an ideal SAR multi-lamination pattern [7]. Since inertial forces come into play, a secondary flow pattern is superposed on the SAR velocity profile of the creeping flow regime. Streamlines seeded at the initial lamellae interface in top view for various Reynolds numbers. The lamellae pattern right at the outlet for the same set of Reynolds numbers were also given. Further simulations showed that for Re above -15 the center lamellae are thinned out until they detach from the top and bottom walls for Re 30 (see center image of Figure 1.128). 

M 70b] [P 63] Photometric concentration profiles were obtained for mixing of 50 mW reactant solutions at 25 °C and K = 246 in a meander micro mixer close to the inlet (see Figure 1.153) [47]. At the start of the mixing process only one lamella is visible, corresponding to about 10 mM reaction product. Further downstream, the next profiles provide a multitude of lamellae, which represent between 2 and 24 mM product. At still further positions in the meander channel, more homogeneous flow patterns are yielded and the product content is increased to between 15 and 28 mM. Finally, the concentration increases to values close to 50 mM which indicates complete mixing. 

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