fat (redirected from boiling (burning) fat)

fat: see fats and oils; obesity.

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fat

Any organic compound of plant or animal origin that is not volatile, does not dissolve in water, and is oily or greasy. Chemically, fats are identical to animal and vegetable oils, consisting mainly of triglycerides (esters of glycerol with fatty acids). Fats that are liquid at room temperature are called oils. Differences in melting temperature and physical state depend on the saturation of the fatty acids and the length of their carbon chains. The glycerides may have only a few different component fatty acids or as many as 100 (in butterfat). Almost all natural fats and oils incorporate only fatty acids that are constructed from two-carbon units and thus contain only even numbers of carbon atoms. Natural fats such as corn oil have small amounts of compounds besides triglycerides, including phospholipids, plant steroids, tocopherols (vitamin E), vitamin A, waxes, carotenoids, and many others, including decomposition products of these constituents. Sources of fats in foods include ripe seeds and some fruits (e.g., corn, peanuts, olives, avocados) and animal products (e.g., meat, eggs, milk). Fats contain more than twice as much energy (calories) per unit of weight as proteins and carbohydrates. Digestion of fats in foods, often partial, is carried out by enzymes called lipases. The breakdown products are absorbed from the intestine into the blood, which carries microscopic fat droplets reconstituted from digested fats (or synthesized in cells) to sites of storage or use. Fats are readily broken down—primarily into glycerol and fatty acids—by hydrolysis, a first step for many of their numerous industrial uses. See also lipid.

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(File Allocation Table) The original file system used in DOS, Windows and OS/2. The FAT keeps track of where data are stored on disk. When the disk is high-level formatted, the FAT is recorded twice and contains a table with an entry for each disk cluster.

The directory list, which contains file name, extension, date, etc., points to the FAT entry where the file starts. If a file is larger than one cluster, the first FAT entry points to the next FAT entry where the second cluster of the file is stored and so on to the end of the file. If a cluster becomes damaged, its FAT entry is marked as such and that cluster is not used again. The original 16-bit version of the FAT (FAT16) supported hard disk partitions as small as a floppy disk up to 4GB and files as large as 2GB. The 32-bit version (FAT32) dramatically increased capacity limits. See FAT32, NTFS and inode.

The FAT Table

The file RESUME.DOC is stored in clusters 0, 2, 3 and 7. The directory entry points to cluster 0 where the file begins. The entry for cluster 0 points to cluster 2 and so on. BUDGET.XLS is stored in clusters 1, 4, 8 and 9.

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FAT - File Allocation Table