Reflective coloration

The terms FD C, D C, and External D C (Ext. D C), which are part of the name of colorants, reflect the FDA s colorant certification. FD C dyes may be used for foods, dmgs, and cosmetics D C dyes are allowed in dmgs and cosmetics and Ext. D C dyes are permitted only in topical products. Straight colorants include both the organic dyes and corresponding lakes, made by extending the colorant on a substrate such as aluminum hydroxide or barium sulfate. The pure dye content of these lakes varies from 2 to 80% the organic dyes contain over 80% pure dye. Colorants certified for cosmetic use may not contain more than 0.002% of lead, not more than 0.0002% of arsenic, and not more than 0.003% of heavy metals other than lead and arsenic. 

H5rak, P., Ots, I., Vellau, H., Spottiswoode, C., and Mpller, A. P. 2001. Carotenoid-based plumage coloration reflects hemoparasite infection and local survival in breeding great tits. Oecologia 126 166-173. 

The complementary color particles will absorb some of the same wavelengths as the original color reflected thereby decreasing the number of originally reflected wavelengths and thus the color intensity. 

Another way to decrease the intensity of a color is to add black pigment, which will absorb some wavelengths that the color reflects. 

Attempts in this laboratory to characterize real or artificial aging with other kinds of analytical observations (color, reflectance, pH, etc.) and to subject these data in turn to Arrhenius plots has been even less successful. In general, the magnitude of the observed change and the inherent analytical errors do not allow Arrhenius plots. Among the test methods used, folding endurance is unusually sensitive compared with other test methods with respect to aging and component composition. 

Figure 10-11. The method ranking system. Colors reflect suitability rankings based on user criteria for retention, resolution, and run time as per equation (10-5).

Objects and substances absorb some colors of light and reflect others. Changes in the molecular structure of substances often change the colors absorbed and the colors reflected. 

Contemporaneous D/0 signals are shown in Fig. 7.22 for sediment cores from the Santa Barbara Basin (SBB), the Cariaco Basin (CB) in Venezuela, the Bermuda Rise (BR), and the GISP2 ice core. Planktonic foraminiferan 8 0 indicates surface water temperature change in SBB and BR the color reflectance change of the CB sediments is controlled by the oxidation state of the overl5dng waters. There are many locations where Y/D events have been well documented (Broecker, 2004) and many others with the full suite of D/0 events. 

One colorimetric technique still in use in archaeology is a field test for soil phosphate. Phosphate in soils and sediments is an indicator of past human activity. Phosphate testing of soil samples is used to look for such indications (Fig. 4.4). A small sample of soil is mixed with hydrochloric and ascorbic acid to release soluble phosphates. The reaction produces a distinctive blue color in the presence of phosphate and the intensity of the color reflects its concentration. Results can be determined by eye or with the use of an instrument. 

Cholesteric liquid crystals, e.g., those of cholesteroylnonaoate (see Sec. 3.2), produce a Bragg-type scattering, which depends on temperature and angles of incidence and observation. Either total reflection or total transmission of circular polarized light is observed, which effect provides the basis of the dark-bright liquid crystal display in the Schadt-Helfrich cell (Fig. 3.5.3) as well as color reflection. 

On the surface or the superficial structure of the artifact, disintegration is restricted to a simple, applied surface film and the outer surface of the intrinsic fabric. The value of surface materials is generally characterized as surface quality, configuration, color, reflective and refractive qualities, and density. The primary concern for these degraded artifacts is the loss of aesthetic qualities and potential for loss or alteration of surface material. 

Brouillard et al. (1978, 1979) showed that these colors reflect the equilibrium between four structure groups (Figure 6.18) ... 

Wilhelm, K.P, Surber, C., and Maibach, H.l. (1989). Quantification of sodium lauryl sulfate irritant dermatitis in man comparison of four techniques skin color reflectance, transepidermal water loss, laser Doppler flow measurement and visual scores. Arch. Dermatol. Res., 281 293-295. 

Mix, A. C., W. Rugh, N. G. Pisias, S. Viers, T. Hagelberg, S. Hovan, A. E. S. Kemp, M. Leinen, M. Levitan C. Ravelo, 1992. Color reflectance spectroscopy a tool for the rapid characterization of deep-sea sediments. Proc. ODP, Init. Repts, 138. College Station, TX. (Ocean Drilling Program) 67-77. 

Color reflectance spectroscopy The measurement of the reflectance of light in separate channels (wavelengths) usually within the visible and near-infrared bands. 

Spectral reflectometer An instrument for measuring color reflectance. 

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