Plasma medicine Plasma medicine Plasma medicine is an emerging field that combines plasma physics, life sciences and clinical medicine. It is being studied in disinfection, healing, and cancer. Most of the research is in vitro and in animal models. It uses ionized gas (physical plasma) for medical uses or dental applications . Plasma, often called the fourth state of matter, is an ionized gas containing positive ions and negative ions or electrons, but is approximately charge neutral on the whole. The plasma sources used for plasma medicine are generally low temperature plasmas, and they generate ions, chemically reactive atoms and molecules, and
Negative number the rules of signs for expanding the multiplication formula_3, and al-Karaji wrote in his "al-Fakhrī" that "negative quantities must be counted as terms". In the 10th century, Abū al-Wafā' al-Būzjānī considered debts as negative numbers in "A Book on What Is Necessary from the Science of Arithmetic for Scribes and Businessmen". By the 12th century, al-Karaji's successors were to state the general rules of signs and use them to solve polynomial divisions. As al-Samaw'al writes: the product of a negative number — "al-nāqiṣ" — by a positive number — "al-zāʾid" — is negative, and by a negative number is positive.