Ether

Ethers (/ˈiːθər/) are a class of organic compounds that contain an ether group—an oxygen atom connected to two alkyl or aryl groups—of general formula R–O–R'. These ethers can again be classified into two varieties, if the alkyl groups are the same on both sides of the oxygen atom then it is a simple or symmetrical ether. Whereas if they are different the ethers are called mixed or unsymmetrical ethers A typical example is the solvent and anesthetic diethyl ether, commonly referred to simply as "ether" (CH₃-CH₂-O-CH₂-CH₃). Ethers are common in organic chemistry and pervasive in biochemistry, as they are common linkages in carbohydrates and lignin.

Structure and bonding

Ethers feature C-O-C linkage defined by a bond angle of about 110° and C-O distances of about 140 pm. The barrier to rotation about the C-O bonds is low. The bonding of oxygen in ethers, alcohols, and water is similar. In the language of valence bond theory, the hybridization at oxygen is sp³.

Oxygen is more electronegative than carbon, thus the hydrogens alpha to ethers are more acidic than in simple hydrocarbons. They are far less acidic than hydrogens alpha to carbonyl groups (such as in ketones or aldehydes), however.

Robert Etheridge, Junior

Robert Etheridge (23 May 1847 – 4 January 1920) was a British palaeontologist who made important contributions to the Australian Museum.

Biography

Etheridge was born in Cheltenham, Gloucestershire, England, the only son of the palaeontologist, Robert Etheridge and his wife Martha, née Smith. He was educated at the Royal School of Mines, London, under Thomas Huxley, and was trained as a palaeontologist by his father.

In 1866 Etheridge came to Australia, working under Alfred Richard Cecil Selwyn on the Victorian geological survey until it was terminated in 1869, and returned to England in 1871. Two years later he was appointed palaeontologist to the geological survey of Scotland, and in 1874 obtained a position in the geology department in the Natural History Museum at South Kensington. While there in co-operation with P. H. Carpenter he compiled a valuable Catalogue of the Blastoidea. In 1878–1880 with H. Alleyne Nicholson, Etheridge published a Monograph of the Silurian Fossils of the Girvan District in Ayrshire.

Xenosaga

Xenosaga (ゼノサーガ, Zenosāga) is a series of science fiction video games developed by Monolith Soft and published by Bandai Namco. Xenosaga's main story is in the form of a trilogy of PlayStation 2 video games. There have been three spin-off games and an anime adaptation. The Xenosaga series serves as a spiritual successor to the game Xenogears, which was released in 1998 for the PlayStation by Square. The creator of both Xenogears and Xenosaga is Tetsuya Takahashi, who left Square in 1998 along with Hirohide Sugiura. Using funds from Namco, they started MonolithSoft and the Xenosaga project.

The first game in the trilogy, Episode I: Der Wille zur Macht was released in February 2002 in Japan, and in February 2003 in North America. Xenosaga Freaks, a lighthearted game with a playable demo for Episode II, was released in April 2004 in Japan, but was not released elsewhere. Episode II: Jenseits von Gut und Böse was released in June 2004 in Japan and February 2005 in North America. Xenosaga: The Animation, an anime based on Episode I, premiered on TV Asahi in Japan on January 5, 2005. Xenosaga Pied Piper, a three chapter-long cellphone-based game depicting the history of cyborg "Ziggurat 8" 100 years before the start of Episode I, was released in Japan in July 2004. Released on July 6, 2006, Episode III: Also sprach Zarathustra is the final title in the Xenosaga series; six episodes were originally projected, but by the time Episode III was released, Namco had already established that it would be the last entry, effectively halving the series. A retelling of the first two episodes titled Xenosaga I & II was released on the Nintendo DS in March 2006 in Japan.