Swiss cheese structure

In view of the difficulties usually experienced in producing BLM of area 0.008 cm, porous structures have been used to form mini-membranes. Two examples of this are nylon polymer films grown at an interface and polycarbonate films normally employed in organic chemistry for the purpose of filtration (21,22). In the former case, a nylon film was synthesized at the interface between water and an organic solvent. Electron microscopy showed that the polymer structure was close-packed on one with a Swiss-cheese structure on the other. Treatment of the films with lipid solution resulted in functional mini-membranes. Polycarbonate films can be employed in a similar manner. Although such systems are relatively simple to work with, one large imponderable is the overall area of membrane produced for study. 

Figure 8. The Swiss-cheese structure of thermal APDs in compounds with two APB variants (Engiish, 1966). (Reprinted with permission from Transactions of the Metallurgical Society, 236,14-18 (1966), a publication of the Minerals, Metals Materials Society, Warrendale, Pennsylvania 15086)...

The ability of MIR to monitor fundamental vibrations of several functional groups provides a new tool for researchers to look at minor compounds in cheese. Some of its early applications were focused on the analysis of macromolecules in cheese such as fat, moisture, and protein (Chen et ah, 1998 McQueen et ah, 1995). More recently, the chemical parameters of cheese (Martfn-del-Campo et ah, 2007), composition (Rodriguez-Saona et ah, 2006), protein structure and interactions during ripening (Mazerolles et ah, 2001), and ripening of Swiss cheese (Martin-del-Campo et ah, 2009) were analyzed with improved techniques. Almost all attempts have been directed toward the determination of macromolecules in cheese. This is mainly because of difficulties in sampling procedures and the heterogeneous nature of cheese (McQueen et ah, 1995) that make analysis of minor compounds difficult. 

Fig. 1.5. (a) A typical link-element structure in the Swiss-cheese model of continuum percolation in two dimensions. The channel width is denoted by 6. (b) The dashed lines indicate the outline of the rectangular bond which approximates the narrow neck of a channel. 

Usually, an accident is caused not by a single event but by the occurrence of several concurrent events, sometimes called Swiss cheese effect, in which corrosion phenomena occur at the microscopic and macroscopic levels and cause strong deterioration of material properties, leading to the failure of a structure. In such situations, the solution to a problem can be the identification of a corrosion barrier that hinders the concatenation of events that would lead to failure. 

The variety of structures encountered in microemulsions offers great versatility for choosing the locus of polymerization. Besides polymerization in globular microemulsions, several studies have dealt with polymerization of monomers in the other phases of microemulsions. One of the main goals underlying these studies was to use the microstructure of microemulsions as a template to produce solid polymers with similar characteristics. For example, incorporation of large amount of hydrophobic monomers in the continuous phase of W/O microemulsions should yield solid polymers with a Swiss cheese-like structure capable of encapsulating the disperse phase (water). This would allow the inclusion of materials (metallic colloidal particles as catalysts, photochromic compounds, etc.) in the disperse phase that would otherwise be insoluble in the polymer. 

The role of voids in the structure of a-Ge and a-Si was discussed in some detail by Ehrenreich and TumbuU (1970) which propose a tentative swiss cheese model in which voids of different sizes are included into a random network. The presence and coalescence of such voids by the annealing of a-Ge films has been detected by electron microscopy by Barna, Bama, and Pocza(1972). 

It was also noticed that the RBDs of all three groups had an AND-gate at the top which signifying a parallel structure. As mentioned earher, this imphes the existence of a set of barriers that were all insufficient to prevent the disaster (as illustrated in the Swiss cheese model proposed by Reason (1997)). 

In Swiss and Gouda-type cheeses, the curd is first formed into a mass and pressure is applied. The whey is drained, but pressure on the curd is maintained. As the pH drops from 6.4-6.5 at draining to 5.2-5.3 in the finished cheese, the curd fuses into a very tight, smooth structure. 

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