Medical research

Research shows that DOPA protects against melanoma

People with light skin tones are far more likely to develop melanoma skin cancer than people with dark skin tones. This large disparity results from far more than can be explained by the UV protective effects of melanin pigment, ...

Ophthalmology

High-tech imaging reveals details about rare eye disorder

Using a new imaging technique, researchers from the National Eye Institute have determined that retinal lesions from vitelliform macular dystrophy (VMD) vary by gene mutation. Addressing these differences may be key in designing ...

Genetics

Study finds loss of 'youth' protein may drive aging in eye

Loss of the protein pigment epithelium-derived factor (PEDF), which protects retinal support cells, may drive age-related changes in the retina, according to a new study in mice from the National Eye Institute (NEI). The ...

Neuroscience

Developing a new human cell line to study blinding eye disorders

Under the direction of Boyd Professor Nicolas Bazan, MD, Ph.D., scientists at LSU Health New Orleans Neuroscience Center of Excellence have developed a new, experimental human cell line from retinal pigment epithelial cells. ...

Diseases, Conditions, Syndromes

Eyes a haven for Ebola and other viruses

A specific cell within our retina, the light-sensitive part of our eyes responsible for sending visual information to our brain, appears to be particularly good at housing Ebola and other viruses, new research has found.

Genetics

Streamlining stem cells to treat macular degeneration

As we age, so do our eyes; most commonly, this involves changes to our vision and new glasses, but there are more severe forms of age-related eye problems. One of these is age-related macular degeneration, which affects the ...

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Pigment

A pigment is the material that changes the color of light it reflects as the result of selective color absorption. This physical process differs from fluorescence, phosphorescence, and other forms of luminescence, in which the material itself emits light.

Many materials selectively absorb certain wavelengths of light. Materials that humans have chosen and developed for use as pigments usually have special properties that make them ideal for coloring other materials. A pigment must have a high tinting strength relative to the materials it colors. It must be stable in solid form at ambient temperatures.

For industrial applications, as well as in the arts, permanence and stability are desirable properties. Pigments that are not permanent are called fugitive. Fugitive pigments fade over time, or with exposure to light, while some eventually blacken.

Pigments are used for coloring paint, ink, plastic, fabric, cosmetics, food and other materials. Most pigments used in manufacturing and the visual arts are dry colourants, usually ground into a fine powder. This powder is added to a vehicle (or matrix), a relatively neutral or colorless material that acts as a binder.

The worldwide market for inorganic, organic and special pigments had a total volume of around 7.4 million tons in 2006. Asia has the highest rate on a quantity basis followed by Europe and North America. In 2006, a turnover of 17.6 billion US$ (13 billion Euro) was reached mostly in Europe, followed by North America and Asia.

A distinction is usually made between a pigment, which is insoluble in the vehicle (resulting in a suspension), and a dye, which either is itself a liquid or is soluble in its vehicle (resulting in a solution). The term biological pigment is used for all colored substances independent of their solubility. A colorant can be both a pigment and a dye depending on the vehicle it is used in. In some cases, a pigment can be manufactured from a dye by precipitating a soluble dye with a metallic salt. The resulting pigment is called a lake pigment.

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