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Ammonium Definition Ammonium is a positively charged ion, NH4, derived from ammonia and found in a wide variety of organic and inorganic compounds. Compounds of…

Schwann cell Definition Schwann cell is any of the cells that cover the axons in the peripheral nervous system and form the myelin sheath. It…

Ethanium Definition Ethanium is a trypanocidal agent and possible antiviral agent that are widely used in experimental cell biology and biochemistry. Ethidium has several experimentally…

Basic Definitions Relating to Numbers Basic numbers are the haploid number of chromosomes; specifically the lowest haploid number of a polyploid series. Some key points…

Moissanite Definition Moissanite is a rare gem that has almost all of the qualities of a diamond. It was first discovered in 1893, with the…

Myelin Definition Myelin is a whitish, fatty substance that forms a sheath around many vertebrate nerve fibers. Myelin insulates the nerves and permits the rapid…

Silicon Carbide Definition Silicon carbide (SiC) is an extremely hard bluish-black insoluble crystalline substance produced by heating carbon with sand at a high temperature and…

Magic Acid Definition Magic acid is a superacid consisting of a mixture, most commonly in a 1:1 molar ratio, of fluorosulfuric acid (HSO3F) and antimony…

Neuroglia Definition Neuroglia is the delicate connective tissue which supports and binds together the nervous elements of the central nervous system. One part of it,…

Germanium Definition Germanium is a brittle, crystalline, grayish-white metalloid element that is found in coal, in zinc ores, and in several minerals. Its atomic number…

Adding Fractions with Different Denominators A very difficult area for many people is fractions, especially when you begin adding. This can become even more complex…

Ependyma Definition Ependyma is the membrane lining the ventricles of the brain and the central canal of the spinal cord. It is one of the…