Surface defects color

Surface curvature, color coding for, 10 340 Surface defect densities, 9 731 Surface deformation, case hardening by, 16 207-208 Surface diffusion... 

Fig. 16.3 A carbon nanoparticle with surface defects (left), and emission color variations in carbon dots depending on size and type of defects. Adapted from Cao et at. [53] and Sun et at. [54] with kind permission from American Chemical Society (2006 and 2013).

A penetrant dye is sprayed onto the surface of the composite inspected. The liquid infiltrates cavities and is made visible by applying a developer to the surface. Defect size is indicated by the color intensity and the rapidity of infiltration of the liquid penetrant. Two types of penetrant, visible and fluorescent, can be used. Fluorescent dyes are visible under UV light, while the visual dyes are visible under normal light. The choice of the penetrant is function of the material tested and the sensitivity required. Automatic dye penetrant inspection systems exist that transfer and apply the dye, apply the revealing agent (or developer), and finally clean the part after testing. How ever. only specific shapes can be inspected automatically, and manual inspection is still required for most structures. 

The first thing to note is the difference in cluster distribution between the defect and the control simulations Conformations in the top three clusters of the defect simulation make up about 81 % of the total probability of surface-bound states, whereas conformations in the first cluster alone in the control simulation have a similar probability of existing on the surface of just over 78 %. As Fig. 6 shows, this is because areas of shortened alkyl chain lengths caused by depressions in the gold substrate below the SAM surface dramatically disrupt the helical structure that LKal4 normally adopts at interfaces, leading to a wide array of unfolded structures. Nearly, all secondary structure, indicated by the color of the peptide s backbone (i.e., magenta, cyan, and purple indicate turns, coils, and alpha helical residues, respectively), is lost with the addition of the surface defects. Unlike the central... 

Color is an important attribute of food quality (Clydesdale, 1993 Bourne, 1982). Consumers select individual food products such as fruits and vegetables primarily on 2q)pearance attributes such as color, shape, size and surface defects (IFT, 1990). Of these, color may be the most influential, because off-color food is likely to be rejected even when it has good flavor or texture. Conversely, high color quality food products usually have higher market value. Therefore, the development of food with an attractive appearance is an important goal in the food industry. How to sense... 

The color development of photochromic compounds can also be utili2ed as a diagnostic tool. The temperature dependence of the fa ding of 6-nitroindolinospiropyran served as the basis for a nondestmctive inspection technique for honeycomb aerospace stmctures (43). One surface of the stmcture to be exarnined was covered with a paint containing the photochromic compound and activated to a violet color with ultraviolet light. The other side of the stmcture was then heated. The transfer of heat through the honeycomb stmcture caused bleaching of the temperature-dependent photochromic compound. Defects in the honeycomb where heat transfer was inhibited could be detected as darker areas. 

Figure 20. Steps involved in loop formation, (a) Free evolution of the tube in depletive environment (b) formation of an unstable loop at around 3.4 lp (c) gliding of the loop governed by the positions of the two contact points along the fiber and the entry-exit angle (d) trapping of the loop by local defects. The translucent green surface represents the excluded volume for the fluid of hard spheres in (b,c,d) one sees that some of the excluded volume is reduced from the overlap resulting from formation of the loop. See color insert.

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