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In organic chemistry, a lactol is a functional group which is the cyclic equivalent of a hemiacetal (−CH(OH)O−) or a hemiketal (>C(OH)O−). The compound is formed by the intramolecular , nucleophilic addition of a hydroxyl group ( −OH ) to the carbonyl group ( C=O ) of an aldehyde ( −CH=O ) or a ketone ( >C=O ).
Right: a lactol of fructose, a cyclic hemiketal. Hemiacetals commonly exist in nature as aldoses such as glucose , and hemiketals commonly exist in nature as ketoses such as fructose . The favorability of the formation of a strain-free six-membered ring and the electrophilicity of an aldehyde combine to strongly favor the acetal form.
Skin flora, also called skin microbiota, refers to microbiota (communities of microorganisms) that reside on the skin, typically human skin. Many of them are bacteria of which there are around 1,000 species upon human skin from nineteen phyla. [1] [2] Most are found in the superficial layers of the epidermis and the upper parts of hair follicles.
In short, melasma is a chronic skin condition that appears as darkened areas on the face due to an overproduction of melanin, says Gina Charles, MO, a family physician specializing in skincare. It ...
The oily-skin type is not necessarily bad, since such skin is less prone to wrinkling, or other signs of ageing, [8] because the oil helps to keep needed moisture locked into the epidermis (outermost layer of skin). The negative aspect of the oily-skin type is that oily complexions are especially susceptible to clogged pores, blackheads, and ...
Manhattan-based dermatologist Dr. Brendan Camp, M.D., said that toasted skin syndrome, officially known as erythema ab igne (EAI), is a "pattern of discoloration that occurs in areas of skin after ...
Some skin secretions are associated with body hair. Skin secretions originate from glands that in dermal layer of the epidermis. Sweat, a physiological aid to body temperature regulation, is secreted by eccrine glands. Sebaceous glands secrete the skin lubricant sebum. Sebum is secreted onto the hair shaft and it prevents the hair from splitting.
Skin absorption relates to the degree of exposure to and possible effect of a substance which may enter the body through the skin. Human skin comes into contact with many agents intentionally and unintentionally. Skin absorption can occur from occupational, environmental, or consumer skin exposure to chemicals, cosmetics, or pharmaceutical ...