Yellow Mask

Storage, Shipping, and Handling. Phosphoms pentachloride is in the EPA extreme ha2ardous substance Hst. It is treated as a dammable sohd, and containers in which it is stored or shipped must be affixed with a yellow acid label DOT UN No. 1806. In general, the pentachloride should be handled with the same precautions that are used with the trichloride. Protective clothing should be worn by workers handling the pentachloride and gas masks should be used when personnel are exposed to the vapors. 

Pale yellow colour (now commonly masked with dyes). 

From the perspective of the strategies aimed at fabrication of efficient blue LEDs, the results outlined above regarding yellow LPPP light emitting diodes are, nevertheless, unsatisfactory. In order to prepare blue LEDs from LPPP materials, it is necessary to efficiently mask out or suppress the dominant yellow aggregate emission. 

The solution may have a brown tint, partially masking the yellow color of the quinone. The dark color is probably due to reaction of the diethylamine with the 2,5-dichloro-3,6-di-fcr -butyl-l,4-benzoquinone. 

Both chlorophylls and carotenoids occur in all green leaves, but their color is masked by chlorophyll in photosynthetic tissues. When the chlorophylls break down as leaves senesce (mature), the yellow and orange carotenoids persist and the leaves turn yellow. Carotenoids are responsible for the colors of familiar animals such as lobsters, flamingos, and fish. Often people are unaware of the chemical nature of food colorants. ... 

Diagnosis Be suspicious if an aerosol attack occurs in the form of yellow rain with droplets of yellow fluid contaminating clothing and the environment. Confirmation requires testing of blood, tissue and environmental samples. As for treatment, there is no specific antidote however, super-activated charcoal should be given orally if the toxin is swallowed. The only defense is to wear a protective mask and clothing during an attack. No specific immunotherapy or chemotherapy is available for use in the field. 

In actual practice, the concentration of chromate produces an intense yellow colour to such an extent that the end point is masked. Therefore, normally concentrations of 5 x 10 3 M are employed in analytical procedures. It suggests that [Ag+] shall be > 1.3 / 10 5 M at the end-point thereby introducing a positive determinate error. However, it has been proved experimentally that even with concentrations as low as 2 x 10 3 M, the extent of error caused is negligibly small. 

Except for the top soil where the colour caused by Fe oxides is often masked by hu-mics, most of the soil profile receives its brown, yellow or red colour from Fe oxides (Bigham Ciolkosz, 1993). Because this is so obvious to the naked eye, soils have been named according to colour in most national classification systems, e. g. red-yellow podzols (USA), sol ochreux (France), Braunerde (Germany), krasnozem (Russia), terra rossa (Italy), and even the current modern international systems (U.S. Soil Taxonomy system and World Reference Base for Soil Resources, WRB) use colour connotations such as Rhodic (red) and Xanthic (yellow). 

The pale yellow color in feldspar is due to Fe " in a tetrahedral Si/Al site. This color is often masked by the pervasive turbidity of common feldspars. A smoky color, the result of radiation damage from the decay of K-40, is also common but often masked. The blue color in the amazonite variety of potassium feldspar (and pale-blue albite) is from the interaction of trace amounts of Pb " in the feldspar with ionizing radiation. Lead-containing feldspars with a higher... 

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