investment trust or closed-end trust Financial organization that pools the funds of its shareholders and invests them in a diversified port¬ folio of securities. It differs from a mutual fund, which issues units repre¬ senting diversified holdings rather than shares in the company itself. Investment trusts have a fixed number of shares for sale; their price depends on the market value of the underlying securities and on the demand for and supply of shares. The first modern investment trusts were formed in England and Scotland as early as 1860. Many early U.S. invest¬ ment trusts failed with the collapse of the stock market in 1929, but oth¬ ers have since prospered under stricter federal regulation.
lo \'I-o\ In Greek mythology, the daughter of the river god Argos. Io drew Hera’s jealousy when Zeus fell in love with her. Zeus changed her into a white heifer to protect her. Hera sent the many-eyed creature Argus to watch over the heifer, but Zeus sent Hermes to lull Argus to sleep and kill him. Hera then sent a gadfly to pursue Io, who fled across Europe and crossed the bodies of water later named the Ionian Sea and the Bosporus (“Ford of the Cow”) in her honour. When she arrived in Egypt she resumed her original form. She was later identified with the Egyptian goddess Isis.
iodine Nonmetallic chemical element, chemical symbol I, atomic num¬ ber 53. The heaviest nonradioactive halogen, it is a nearly black crystal¬ line solid (diatomic molecule I 2 ) that sublimes (see sublimation) to a deep violet, irritating vapour. It is never found in nature uncombined. Its sources (mostly in brines and seaweeds) and compounds are usually iodides; iodates (small amounts in saltpeter) and periodates also occur. Dietary iodine is essential for thyroid gland function; in areas of the world where food contains insufficient iodine, an iodine compound such as potassium iodide (KI) is added to table salt (sodium chloride) to prevent iodine deficiency. Elemental iodine is used in medicine, in synthesizing some organic chemicals, in manufacturing dyes, in analytical chemistry (see analysis) to measure fat saturation (see hydrogenation) and to detect starch, and in photography. The radioactive isotope iodine-131 (see radio¬ activity), with an eight-day half-life, is very useful in medicine (see nuclear medicine) and other applications.
iodine deficiency Inadequate intake or metabolism of iodine. It directly affects thyroid secretions, which influence heart action, nerve response, growth rate, and metabolism. Simple goitre, the most frequent result, is most common in areas without access to salt water and is rare
along seacoasts. Severe, prolonged deficiency can cause hypothyroidism. Eating seafood regularly or using iodized table salt will prevent iodine deficiency. Some countries have made dietary iodine additives mandatory.
ion Atom or group of atoms with one or more positive or negative elec¬ tric charges. Positively charged ions are cations, negatively charged ones anions. Ions are formed when electrons are added to or removed from neutral molecules or other ions, as sodium (Na) and chlorine (Cl) atoms react to form Na + and Cl - ; when ions combine with other particles, as hydrogen cations (H + ) and ammonia (NH 3 ) combine to form ammonium cations (NH 4 + ); or when a covalent bond between two atoms is ruptured in such a way that the resulting particles are charged, as water (H 2 0) dis¬ sociates (see dissociation) into hydrogen and hydroxide ions (H + and OH - ). Many crystalline substances (see crystal) are composed of ions held in regular geometric patterns by the attraction of oppositely charged par¬ ticles for each other. Ions migrate to the electrode of opposite charge in an electric field and are the conductors of current in electrolytic cells (see electrolysis). Compounds that form ions are called electrolytes. Ions are also formed in gases when heated to very high temperatures or when an electrical discharge passes through them (see plasma).
ion-exchange resin Any of a wide variety of synthetic polymers con¬ taining positively or negatively charged sites that can interact with or bind to an ion of opposite charge from a surrounding solution. Light, porous solids in granules, beads, or sheets, they absorb the solution and swell as they attract the target ions; when exhausted, they are removed from use and regenerated by an inexpensive brine or carbonate solution. A solid support of styrene-divinylbenzene copolymer to which are attached sul¬ fonic or carboxylic acid groups is often used to attract and exchange cat¬ ions (e.g., ions of hydrogen or metals). Quaternary ammonium groups on the solid matrix are used to attract anions (e.g., ions of chlorine). Indus¬ trially, the resins are used to soften hard water, purify sugar, and concen¬ trate valuable elements (gold, silver, uranium) from their ores. In the laboratory they are used to separate and concentrate substances and some¬ times as catalysts. Zeolites are minerals with ion-exchange properties.
Ionesco \yo-nes-'ko\ / Eugene orig. Eugen lonescu (b. Nov. 26, 1909, Slatina, Rom.—d. March 28,
1994, Paris, France) Romanian-born French playwright. He studied in Bucharest and Paris, where he lived from 1945. His first one-act “anti¬ play,” The Bald Soprano (1950), inspired a revolution in dramatic techniques and helped inaugurate the Theatre of the Absurd. He followed it with other one-act plays in which illogical events create an atmosphere both comic and grotesque, including The Lesson (1951), The Chairs (1952), and The New Tenant (1955).
His most popular full-length play,
Rhinoceros (1959), concerns a pro¬ vincial French town in which all the citizens are metamorphosing into rhinoceroses. Other plays include Eugene Ionesco, 1959.
Exit the King (1962) and A Stroll in markgerson the Air (1963). He was elected to the Academie Fran§aise in 1970.
Ionia M-'o-nyoV Ancient region, western coast of Asia Minor (modem Turkey) bordering the Aegean Sea. It consisted of a coastal strip that extended from the mouth of the Hermus River to the Halicarnassus Pen¬ insula, a distance of 100 mi (160 km). In the 8th century bc there were 12 major Greek cities in the region, including Phocaea, Erythrae, Colophon, and Miletus on the mainland, and the islands Chios and Samos. It was very prosperous, and until 500 bc Ionic philosophy and architecture and the Ionic dialect were highly influential in Greece. In the mid-6th century bc it fell to Lydia and then to the Persians. After a brief period of independence beginning in 334 bc, it became part of the Seleucid kingdom. In 133 bc it passed to the Romans and became part of the Roman province of Asia. It was devastated during the Turkish conquest of Asia Minor.
Ionian Any ancient Greek inhabitant of Ionia, from the time of the col¬ lapse of Mycenae. Ionian cities colonized southern Italy and opened up the Black Sea from c. 700 bc. Their contributions to Greek culture
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Ionian ► IQ I 955
included the epics of Homer and the earliest elegiac and iambic poetry. They began the study of geography, philosophy, and historiography in the 6th century. After Alexander the Great their literary language was the basis of Koine, or “common speech,” the language of practically all Greek writ¬ ing to the present day.
Ionian \I-'o-ne-3n\ Islands ancient Heptanesos Group of seven Greek islands (pop., 2001: 214,274) in the Ionian Sea. They include Corfu, Cephalonia, Zacynthus, Leucas, Ithaca, Cythera, and Paxos and have a combined land area of 891 sq mi (2,307 sq km). Controlled by Venice in the 15th and 16th centuries, they were taken by Russian and Turkish forces in 1799. In 1815 the Treaty of Paris placed them under the control of Britain; the British ceded them to Greece in 1864.