Cross-sectional structures

Kim HM, Cho BR (2009) Two-photon materials with large two-photon cross sections. Structure-property relationship. Chem Commun 2 153-164... 

Figure 15.30 TEM and electron diffraction images of Pt nanoparticles (diameter 2.5 nm) with mesoporous frameworks of mesoporous silica thin films from different planes [100] (a) and [210] (b) (c) cross-section structure of a single electron soliton device of Pt nanoparticle/mesoporous silica film on a Si substrate connected with two Al electrode.

The cross-sectional structure of the buccal mucosa is shown in Fig. 2.7. The buccal mucosa consists of the epithelium and the underlying connective tissue, the lamina propria, separated by a basement membrane. 

The Lorentzian profile (20) is going to appear often later in the resonance theory. It is a symmetric peak with a maximum at E = Er. The full width at half the maximum (FWHM) of this peak is r, and hence, the FWHM of the symmetric peak in Figure 4.1 is T if transformed into a function of the energy E. Therefore, the cross-section structure, i.e., the resonance structure, is narrower for smaller r. A feature of the Lorentzian profile (20) to be noted is that the width parameter T also determines its peak height 4h/ L. This fact will be taken advantage of in the resonance analysis procedure, as will be explained in Section 2.2.5. 

Cross-section structure. An anisotropic membrane (also called asymmetric ) has a thin porous or nonporous selective barrier, supported mechanically by a much thicker porous substructure. This type of morphology reduces the effective thickness of the selective barrier, and the permeate flux can be enhanced without changes in selectivity. Isotropic ( symmetric ) membrane cross-sections can be found for self-supported nonporous membranes (mainly ion-exchange) and macroporous microfiltration (MF) membranes (also often used in membrane contactors [1]). The only example for an established isotropic porous membrane for molecular separations is the case of track-etched polymer films with pore diameters down to about 10 run. All the above-mentioned membranes can in principle be made from one material. In contrast to such an integrally anisotropic membrane (homogeneous with respect to composition), a thin-film composite (TFC) membrane consists of different materials for the thin selective barrier layer and the support structure. In composite membranes in general, a combination of two (or more) materials with different characteristics is used with the aim to achieve synergetic properties. Other examples besides thin-film are pore-filled or pore surface-coated composite membranes or mixed-matrix membranes [3]. 

Figure 2.1 Polymeric membrane shapes and cross-sectional structures. Tubular membranes are similar to flat sheet membranes because they are cast on a macroporous tube as support. Capillary membranes are hollow fibers with larger diameter, that is, >0.5 mm.

There are many different shaped profiles. These profiles identify many varieties of shapes. Pipes and tubes could be included but the industry has had them classified as a separate category because they represent major and large markets on their own. Profiles normally identify shapes that are noncircular or are not symmetrical. However, there are exceptions where extruded products, such as capillary tubing and rod, are usually called profiles. They can be solid, hollow, or a combination of solid and hollow. Popular shapes include many hollow sections such as in window frame profiles, tapes, edgings, and gaskets as well as a combination of rods with different cross sections structural shapes in the form of Ts, Us, Is, Hs, squares, etc. The product shapes and sizes are as limitless as the number of applications. 

Step coverage — From the process flow schematics shown previously, it is apparent that printed transistors inherently have substantial topology within their cross-sectional structure. As a consequence, step coverage becomes an important parameter in process optimization. Given the large steps (typically several tens of nm or more) and the use of relatively thin subsequent layers, it is important that the layers cover each other adequately liquids must be able to coat the vertical sidewaUs of steps during a multilayer print process. This places constraints on fluid viscosity, evaporation rate, wetting, etc. 

Fig. 1 (A) Cross-sectional structure of the human nose. NV = nasal vestibule AT = atrium NP = nasopharynx IT = interior turbinate and orifice of the nasolacrimal duct MT = middle turbinate and orifices of frontal sinus, anterior ethmoidal sinuses, and maxillary sinus ST = superior turbinate and orifices of posterior ethmoidal sinuses hatched area, olfactory region. (B) Four major cell types in the nasal epithelium (a) non-ciliated columnar cell with microvilli (b) goblet cell with mucous granules and Golgi apparatus (c) basal cell and (d) ciliated columnar cell with many mitochondria in the apical part. (Reprinted from Ref. with permission from Elsevier.)...

Figure 6.22. Microstructure of CVD SiC coaling by different CVD methods [44] (a) surface morphology by conventional CVD, (b) surface morphology by CNTD, (c) cross-section structure by conventional CVD and (d) cross-section structure by CNTD...

Hirai, Y. Harada, S. Kikuta, H. Tanaka, Y. Okano, M. Isaka, S. Kobayasi, M. Imprint lithography for curved cross-sectional structure using replicated Ni mold. J. Vacuum Sci. Technol. B. 2002, 20 (6), 2867-2871. 

The processes used to prepare cellulosic membranes generally lead to homogenous cross-sectional structures. Cellulose prepared from xanthate derivatives may exhibit a cuticle or skin structure however, this asymmetry does not produce significant resistance to mass transfer. Most membranes currently used for hemodialysis are prepared via the cuprammonlum process. These membranes do not form a skinned structure during coagulatlon/regeneratlon. 

Fig. 8 Surface and cross-sectional structures of coatings after themial cycle test...

Cross-sectional structures of the four Jovian moons lo (upper left corner), Europa (upper right corner), Ganymede (lower left corner), Callisto (lower right corner)... 

The electrode material has also been found to influence the surface morphology of electrochemically prepared PPy films. In our own work, we used transmission electron microscopy (TEM) to investigate the cross-sectional structure of PPy films prepared on different substrates.165 In all cases, the large surface globules were observed to be the caps of cone-shaped structures that extended to the electrode surface of the PPy him (see Chapter 3). Interestingly, Yoon and coworkers showed that the cauliflower-type surface morphology could be virtually eliminated by carefully polishing the electrode surface.152... 

Figure 6.27 Schematic diagrams illustrating (a) the plan-view and (b) the cross-sectional structure of porous SiC substrate...

FIGURE 1.14 Cross-sectional structures of spray-dried powders by CLSM. Wall materials MD (DE 2 and 20). 

A. Scanning Electron Microscope Observation of Surface and Cross-sectional Structure of Ta20s Thin Films... 

FIGURE 16.15 (a) Typical cross-sectional structure of an optical disk and (b) the intensity profile of the read-out system in binary code as a function of time (t). ffere, T is the transparent polymer support, R is the reflective metal layer, PC is the protective coating, and P represents a depression created for information storage. (Reproduced with permission from HUthig and Wepf Verlag.)... 

Figure 1. Typically asymmetric membrane (a) and composite membrane (b) cross-sectional structures.

Kesting and Fritzsche [5] studied the cross-sectional structure of polysulfone hollow fibers they fabricated using Lewis acid/base complexes as solvents for the spinning solutions. Figures 6.3 and 6.4 are the SEM pictures of the outer edge of the hollow... 

Fujii et al. [13] studied morphological structures of the cross section of various hollow fibers and fiat sheet membranes by high-resolution field emission scanning electron microscopy. Figure 6.8 shows a cross-sectional structure of a flat sheet cellulose acetate RO membrane. The layer near the top surface is composed of a densely packed monolayer of polymeric spheres, which is supported by a layer formed with completely packed spheres. The contours of the spheres in the top layer can be observed. The middle layer is also composed of loosely packed and partly fused spheres, which are larger than the spheres in the surface layer. In the middle layer, there are many microvoids, the sizes of which are the same as the spheres. The layer near the bottom is denser than the middle layer, and the spheres are deformed and fused. Interstitial void spaces between the spheres, which may be called microvoids, are clearly observed. This structure seems common for the flat sheet as well as the hollow fiber membranes. For example. Fig. 6.9 shows a cross section of a hollow fiber made of PMMA B-2 (a copolymer containing methyl methacrylate and a small amount of sulfonate groups). The inside surface layer is composed of the dense structure of compactly packed fine polymeric particles. The particle structure of the middle layer... 

Fig. 6.9. Cross-sectional structure of PMMA B-2 hollow fiber membrane. Reprinted from [13]. Copyright 1992, with kind permission from the Society of Polymer Science, Japan...

As mentioned earlier, the study of the cross-sectional structure of membranes by AFM was hampered by difficulties involved in making a smooth cross-sectional surface. Wood [14] made some earlier studies on the cross section of poly(phenylene oxide) (PPO) hollow fibers. But her attempt did not provide clear information on the nodular structure. 

As discussed, the cross-sectional view of the membranes observed by AFM has similar characteristics to those observed by high-resolution FE-SEM, confirming that AFM can be used to study the cross-sectional structure of polymeric membranes, particularly in terms of their nodular structures. The void spaces between the nodules may form water channels in reverse osmosis and ultraflltration. They may also become defects when they appear at the densely packed monolayer of nodules or nodular aggregates. Information on the nodular structure will therefore help to eliminate the unwanted defects in the skin layer of the asymmetric membranes. 

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