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Drywall water damage in a closet. Drywall is highly vulnerable to moisture due to the inherent properties of the materials that constitute it: gypsum, paper, and organic additives and binders. Gypsum will soften with exposure to moisture and eventually turn into a gooey paste with prolonged immersion, such as during a flood.
Light skin is a human skin color that has a low level of eumelanin pigmentation as an adaptation to environments of low UV radiation. [ 1 ] [ 2 ] Due to migrations of people in recent centuries, light-skinned populations today are found all over the world.
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. [4] It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk.
Typically, light from xenon flash lamps is highly actinic, as is daylight as both contain significant green-to-UV light. In the first half of the 20th century, developments in film technology produced films sensitive to red and yellow light, known as orthochromatic and panchromatic, and extended that through to near infra-red light.
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A bathtub faucet with built-up calcification from hard water in Southern Arizona. Hard water is water that has a high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum, [1] which are largely made up of calcium and magnesium carbonates, bicarbonates and sulfates.
Known as melasma, the condition, which can also occur in men, results from overactive melanocytes, the skin’s pigment cells. Melasma can fade on its own, but in some people it may never go away ...
Gold is a good conductor with a resistivity of 2.44 × 10 −8 Ω·m and is essentially nonmagnetic: = 1, so its skin depth at a frequency of 50 Hz is given by = = Lead, in contrast, is a relatively poor conductor (among metals) with a resistivity of 2.2 × 10 −7 Ω·m , about 9 times that of gold.