Physical colors

The application should state the rationale for the design of the in-use stability tests performed. The procedures used should be fully validated. One key factor is that the test should simulate the use of the product as far as practicable. This should include any reconstitution or dilution prior to use. Aliquots should be removed in an appropriate manner following, as far as possible, the usage pattern that will be encountered in practice. Physical (color, clarity, closure integrity, particulate matter, and particulates/particle size), chemical (assays for active ingredient, antioxidants and... 

Physical color removal technologies that were reported in the literature include adsorption, chemical precipitation, and membrane separation [14—17]. The high cost and disposal problems have opened the door for further investigation of new techniques. The inability of biological treatment processes in degrading azo dye compounds makes physical treatment a necessary stage prior to biotreatment in... 

Some aspects of plant variation could interfere with the impact of natural enemies. Some enemies may be unable to associate microhabitat cues (e.g., chemical, physical, color, position) with prey or host location. For these enemies, prey or host feeding on restricted tissues will tend to appear widely spaced and they may not be readily encountered. It appears to me that many, if not most, parasitoids and predators can be found to use one or more cues. This negative effect could be counteracted by increased encounter rates during herbivore searching movements. 

Perform a test filtration with the selected product samples prior to and after filtration. Results should be examined with regard to chemical stability (i.e., active content, physical, color, etc.). 

On occasion, a colorist may be asked to match to a set of reflectance numbers, or L, A, B coordinates, generated by spectrophotometric measurement of a color standard from a remote location. In other words, he or she will be asked to match a color that they have not seen. While instrumentation technology has improved over recent years, there still may be enough variance between individual spectrophotometer to cause a color rejection. Instruments are extremely helpful quality control tools to measure color and numerically define color differences. However, their use as a device to reduce a color target to a set of numbers and then send that set of numbers to a color formulator as a target for matching is seldom successful. Physical color standards that can be viewed under various light sources are preferred. 

Naugard PS-30 is a liquid amine antioxidant typically used with phenolic antioxidants, phosphites, and synergists in poly-ether polyols to inhibit physical/color scorch associated with the production of flexible urethane foam. 

Vanadinite Pb5(V04)3Cl is generally a strongly colored mineral that rarely shows fluorescence, but the weakest colored varieties, straw-yellow in physical color, can show yellow or greenish-yellow emission. Robbins (1994) notes that such vanadinite from Santa Eulalia, Chihuahua, Mexico is probably endlichite, with a large amount of arsenate substituting for vanadate. 

The objective of this Section is to raise the level of awareness that color needs to be part of any total systems approach to material design. We will survey the major classes of colorants suitable for use in high performance polymer blends and alloys and describe some of the potential chemical and physical colorant/material interactions. 

The most important of the systems not based on collections of physical color samples is what is known as the CIE system. This system was developed by the Commission /nternational de I Eclairage (International Commission on Illumination). 

MW-convective air drying could be used to save in drying time and to produce high-quality dried dill leaves with better physical (color) and sensory attributes... 

In physics, color is a phenomenon of addition or subtraction of parts of the visible spectrum, due to selective absorption or scattering in a material. The light transmission through a sample of thickness at a wavelength X is described by Lambert s law. 

For the visual assessment of a color, a reference sample is needed. Systems of physical color samples are available for reference purposes, such as the Munsell system, DIN color chart. Natural Color System and the more customized RAL and Pantone color charts. The ISO grey scale is defined for the visual assessment of color differences and used for the specification of color tolerances for quality control purposes. 

In this review we detail how the color of mesoporous silicon can be tuned, like many other properties (see handbook chapter Tunable Properties of Porous Silicon ). This has been achieved by both control of the physical structure of silicon at the nanoscale and chemical means. The physical color of porous silicon films, membrane flakes, and photonic crystals is much more easily tuned than those of milled microparticle powders. The latter display various shades of brown, rather than the gray of solid silicon, and this has to date been an obstacle for applications in certain high-volume consumer products. 

Fig. 1 Varied physical colors from ultrathin single layers of stain-etehed mesoporous silicon (LHS- A. Loni unpublished 2009) and anodized mesoporous sihcon photonic crystals (RHS - Gooding Group Univ. New South Wales, Austraha http //www.rsc.org/Publishing/ChemTech/Volume/ 2009/02/biosensors.asp)...

Fig. 4 Physical colors of dark gray solid silicon powder and brown porous silicon powders. The brown hue of mesoporons silicon is tunable via porosity, microparticle size, and oxide content (Loni A (2008) Unpubhshed data. Intrinsiq Materials Ltd)...

Coloration can be physical or chemical (pigmentary) or a combination, and biomimetic versions of the principles involved are contributing to textiles, plastics, and camouflage systems. There are several types of physical coloration, loosely classified as scattering (coherent and incoherent), diffraction, and interference. They can... 

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