Guanine is one of the four main nucleobases found in the nucleic acids DNA and RNA, the others being adenine and thymine. In DNA, guanine is paired with cytosine; the guanine nucleoside is called guanosine. With the formula C5H5N5O, guanine is a derivative of purine, consisting of a fused pyrimidine-imidazole ring system with conjugated double bonds. Being unsaturated, the bicyclic molecule is planar. Guanine, along with adenine and cytosine, is present in both DNA and RNA, whereas thymine is seen only in DNA, uracil only in RNA. Guanine has the major keto form and rare enol form, it binds to cytosine through three hydrogen bonds. In cytosine, the amino group acts as the hydrogen bond donor and the C-2 carbonyl and the N-3 amine as the hydrogen-bond acceptors. Guanine has the C-6 carbonyl group that acts as the hydrogen bond acceptor, while a group at N-1 and the amino group at C-2 act as the hydrogen bond donors. Guanine can be hydrolyzed with strong acid to glycine, carbon dioxide, carbon monoxide.

First, guanine gets deaminated to become xanthine. Guanine oxidizes more than adenine, the other purine-derivative base in DNA, its high melting point of 350 °C reflects the intermolecular hydrogen bonding between the oxo and amino groups in the molecules in the crystal. Because of this intermolecular bonding, guanine is insoluble in water, but it is soluble in dilute acids and bases; the first isolation of guanine was reported in 1844 by the German chemist Julius Bodo Unger, who obtained it as a mineral formed from the excreta of sea birds, known as guano and, used as a source of fertilizer. Between 1882 and 1906, Fischer determined the structure and showed that uric acid can be converted to guanine. Trace amounts of guanine form by the polymerization of ammonium cyanide. Two experiments conducted by Levy et al. showed that heating 10 mol·L−1 NH4CN at 80 °C for 24 hours gave a yield of 0.0007%, while using 0.1 mol·L−1 NH4CN frozen at −20 °C for 25 years gave a 0.0035% yield. These results indicate.

In 1984, Yuasa reported a 0.00017% yield of guanine after the electrical discharge of NH3, CH4, C2H6, 50 mL of water, followed by a subsequent acid hydrolysis. However, it is unknown whether the presence of guanine was not a resultant contaminant of the reaction. 10NH3 + 2CH4 + 4C2H6 + 2H2O → 2C5H8N5O + 25H2A Fischer-Tropsch synthesis can be used to form guanine, along with adenine and thymine. Heating an equimolar gas mixture of CO, H2, NH3 to 700 °C for 15 to 24 minutes, followed by quick cooling and sustained reheating to 100 to 200 °C for 16 to 44 hours with an alumina catalyst, yielded guanine and uracil: 10CO + H2 + 10NH3 → 2C5H8N5O + 8H2OAnother possible abiotic route was explored by quenching a 90% N2–10%CO–H2O gas mixture high-temperature plasma. Traube's synthesis involves heating 2,4,5-triamino-1,6-dihydro-6-oxypyrimidine with formic acid for several hours; the word guanine derives from the Spanish loanword guano, which itself is from the Quechua word wanu, meaning "dung". As the Oxford English Dictionary notes, guanine is "A white amorphous substance obtained abundantly from guano, forming a constituent of the excrement of birds".

In 1656 in Paris, a Mr. Jaquin extracted from the scales of the fish Alburnus alburnus so-called "pearl essence", crystalline guanine. In the cosmetics industry, crystalline guanine is used as an additive to various products, where it provides a pearly iridescent effect, it is used in metallic paints and simulated pearls and plastics. It provides shimmering luster to nail polish. Facial treatments using the droppings, or guano, from Japanese nightingales have been used in Japan and elsewhere because the guanine in the droppings produces a clear, "bright" skin tone that users desire. Guanine crystals are rhombic platelets composed of multiple transparent layers, but they have a high index of refraction that reflects and transmits light from layer to layer, thus producing a pearly luster, it can be applied by dipping. It may irritate the eyes, its alternatives are mica, faux pearl, aluminium and bronze particles. Guanine has a wide variety of biological uses that include a range of functions ranging in both complexity and versatility.

These include camouflage and vision among other purposes. Spiders and some amphibians convert ammonia, as a product of protein metabolism in the cells, to guanine, as it can be excreted with minimal water loss. Guanine is found in specialized skin cells of fish called iridocytes, as well as being present in the reflective deposits of the eyes of deep-sea fish and some reptiles, such as crocodiles. On 8 August 2011, a report, based on NASA studies with meteorites found on Earth, was published suggesting building blocks of DNA and RNA may have been formed extra-terrestrially in outer space. Cytosine Guanine deaminase Guanine MS Spectrum Guanine at

High School Affiliated to Beijing International Studies University

The High School Affiliated to Beijing International Studies University is a public secondary school located in Chaoyang District, Beijing. Founded in 1956, the school is administered by the Education Commission of Chaoyang District and the teaching activities are organised into Junior High and Senior High, it occupies two campuses amounting to ca. 8.65 acres, featuring 24 Junior and 12 Senior teaching classes. The High School Affiliated to Beijing International Studies University is not to be confused with another public school in the district, 中国旅游学院附属中学 the High School Affiliated to China Tourism Institute. While China Tourism Institute was another name for Beijing International Studies University during the 1980s and 1990s, it is more of a historical term, i.e. a China Tourism Institute does not exist in China. In addition, although the school names itself BISU Junior High School in English, there is no official link between the school and the university; the school as a whole was established in 2000 as a merger of three high schools in the neighbourhood.

Its predecessors include Guanzhuang High School and Yangzha High School, both founded in 1956, the 1983-founded Guanzhuang II High School. Shortly after the establishment, the same year in July, the school was named High School affiliated to China Building Materials Academy. In 2011, it became the affiliated school to Beijing International Studies University under the collaborative agreement between the Chaoyang Education Commission and the University. Establishment1956: The precursor of Guanzhuang High School was founded by the Ministry of the Building Material Industry, it served as an education provider for children of the Ministry staff. In 1958 it was merged into the newly built Guanzhuang High School. 1956: The precursor of Yangzha High School was founded as a school for the Hui people in the neighbourhood. It was located on the outskirts of Tongzhou District. In April 1958, the administration was transferred from Tongxian to Chaoyang District. March 1983: Changying Primary School and Daimao Junior High School merged to form the Guanzhuang II High School.

TransformationApril 5, 1986: Guanzhuang High School cooperated with Beijing International Studies University and was renamed High School Affiliated to Beijing International Studies University. November 24, 1995: The High School Affiliated to Beijing International Studies University was merged into the 119 High School as a satellite campus. January 2000: The 119 High School, the Yangzha High School and the Guanzhuang II High School merged to form a new high school. In July, it was named High School Affiliated to China Building Materials Academy. RecentlyMay 5, 2011: Collaborative agreement was signed between the Chaoyang Education Commission and the Beijing International Studies University; the former High School Affiliated to China Building Materials Academy became the High School Affiliated to Beijing International Studies University in September. April 18, 2011: The school's course reform project was approved by the Beijing Education Commission; the featured language courses for Senior High was launched in 2012 under the alliance with Beijing International Studies University.

Beijing International Studies University Schools portal The High School Affiliated to Beijing International Studies University

1939 Ice Hockey World Championships

The 1939 Ice Hockey World Championships were held between February 3 and February 12, 1939, in Zürich and Basel, Switzerland. Austria had been annexed by Germany in 1938, four Austrians played this tournament in German jerseys; the fourteen teams participating in the 1939 World Championship were divided into four preliminary groups: two groups of four and two groups of three. The top two teams in each group advanced to the second round; the eight teams in the second round played in two groups of four, with the top two from each group advancing to the third round. The six teams not advancing to the second round played a consolation round in two groups of 3 teams with the winners of each group playing a one-game play-off for 9th place; the four teams not advancing from the second round played a consolation round for placed 5 through 8. Canada won its eleventh world championship winning all their games while only giving up one goal in the entire tournament; the USA had lost to the Swiss in the semi-final round, but defeated them in the final to claim silver.

The host, won its third European championship by winning a one-game playoff against Czechoslovakia well after the World Championship had concluded. Both teams had decided to play tie-breaking game; the 8-1 victory over the Belgian side would be the last victory for Hungary at the World Championships highest level until 2016 Standings The Executive Board voted to have Italy and Germany replay their game, which ended as a scoreless draw, after which goal differential was used to decide second place. Standings Standings Standings Standings Standings Standings Standings Standings Standings World Champion 1939 Canada Trail Smoke Eaters European Champion 1939 Switzerland Complete results Duplacey, James. Total Hockey: The official encyclopedia of the National Hockey League. Total Sports. Pp. 498–528. ISBN 0-8362-7114-9. Podnieks, Andrew. IIHF Media Guide & Record Book 2011. Moydart Press. Pp. 129–30