Light-conducting pigments

Metallized Glass n Glass spheres, flaks, or fibers that have heen coated with silver or aluminum and, as fillers, provide increased electrical conductivity and light-reflecting pigmentation. 

The most commonly used black pigments are carbon blacks. In addition to being efficient light absorbers, some varieties of these small-particle-size materials impart electrical conductivity and thixotropy to paints. The... 

NOTE The following operations should be conducted in subdued light to reduce pigment fading during extraction. 

To enable the utilization of the full spectral range for classification also in carotenoid-rich species, we propose a method for photodestruction of carotenoid pigments in pollen using 633 nm light. In initial experiments that were conducted at 633 nm excitation, we observed that the bands ascribed to carotenoid molecules were not stable but diminished steadily, even at relatively low excitation intensities of 10 mW. Figure 4.6 displays spectra of horse-chestnut pollen excited with 633 nm as a function of exposure time to the laser. The irreversible decrease of the intensities of the typical carotenoid bands suggests the photodestruction of these molecules (see arrows in Fig. 4.6) [72-74]. With excitation at 785 nm, the spectra of the pollen remained unal-... 

Histological examination was conducted to elucidate cellular changes in photoautotrophic and photomixotrophic green hairy roots stimulated by light. The Chi pigment [39] was found in the cortical cells of photoautotrophic hairy roots observed under a fluorescence microscope as compared with those of the photomixo troph. The heterotrophic hairy roots did not display the Chi pigment (data not shown). 

A major use of selenium has been in photoelectric devices. Its conductivity increases with illumination, and this provides a way of measuring light intensity or operating electrical switches. However, newer types of photocells are available that are made of other materials (such as cadmium sulfide). A second and more important use of selenium is in rectifiers to convert alternating current to direct current. Also, some pigments contain selenium and tellurium compounds, and both elements have been used in vulcanization of rubber. Selenium compounds have been used in dandruff treatment shampoos, and low levels of selenium may be necessary for dietary balance. Some studies have shown that persons whose diets are deficient in selenium may have a higher incidence of heart attacks. 

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