Spots light green

FIGURE 41 Bronze disease. Bronze disease, one of the most serious corrosive processes besetting recovered bronze antiquities, results from the interaction of one component of the patina on ancient bronze, namely, cuprous chloride with atmospheric oxygen, in a damp environment. Small spots of a light green powder (composed mainly of cuprous chloride) that grow rapidly on the surface of the patina are indicative that the bronze disease process is active. Unless the chemical activity of cuprous chloride is inhibited by some conservation procedure, bronze disease generally results in the eventual total destruction of bronze objects. 

Adults are gray moths with a silver spot in the middle of each forewing. They emerge from overwintering pupae in May and lay light green, dome-shaped eggs on the undersides of leaves. 

Moreover, the formation of copper trihydroxychlorides accelerates the corrosion of the remaining metal, and is accompanied by an important volume expansion, which results in a fragmentation of the object. This process known as bronze disease can be identified by the formation of spots or patches of a light green loose powder on the surface of the object (Fig. 5.5). 

NATURE OF DAMAGE. Light-green, watery, angular spots initially on the underside of the leaf. Subsequently spots also become visible on the top of the leaf and turn black. Bacterial mucus is secreted on the underside of the leaf. 

Leaves with yellow or light green spots. 

Color Back is olive-green to dark brown, at times almost black, sides lighter, becoming silvery white below light green or cream-colored wavy lines or vermiculations on top of head and on back, broken up into spots on sides. 

Treatment after spraying Heated 15 min at 100 C. The spots fluoresce green-yellow in long-wave UV light. Amounts of over 2 pig can be detected as brown spots in daylight. 

Figure 7.3 shows the two-beam photon-force measurement system using a coaxial illumination photon force measurement system. Two microparticles dispersed in a liquid are optically trapped by two focused near-infrared beams ( 1 pm spot size) of a CW Nd YAG laser under an optical microscope (1064 nm, 1.2 MWcm , lOOX oil-immersion objective, NA = 1.4). The particles are positioned sufficiently far from the surface of a glass slide in order to neglect the interaction between the particles and the substrate. Green and red beams from a green LD laser (532 nm, 21 kWcm ) and a He-Ne laser (632.8 nm, 21 kW cm ) are introduced coaxially into the microscope and slightly focused onto each microparticle as an illumination light (the irradiated area was about 3 pm in diameter). The sizes of the illumination areas for the green and red beams are almost the same as the diameter of the microparticles (see Figure 7.4). The back scattered light from the surface of each microparticle is...

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