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varešanović started his career with hometown club sarajevo,
varešanović started his career with hometown club sarajevo, breaking into the first team in 1991, but getting only limited playing time. with the start of the bosnian war, competitive football in the country halted and sarajevo became a touring club. during one of these tours, varešanović was spotted by bordeaux scouts...
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68a0c20d618eb121dfa1b23f320325b634746743
in 2010, he started working as a manager.
in 2010, he started working as a manager. during his managerial career, varešanović managed hometown club sarajevo on two occasions, velež mostar, olimpik, the bosnia and herzegovina u18 national team and tuzla city.
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ec7d23aed57728c3e3bccbaa3207ac3212a54982
during his playing career, which spanned nearly 15
during his playing career, which spanned nearly 15 years, he competed in bosnia and herzegovina, france, greece, turkey and austria, playing in france for bordeaux and in greece for olympiacos among others. varešanović also played for the bosnia and herzegovina national team in the late 1990s and early 2000s.
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013c0be222a7cc675902bc2ada6ec52738d88454
topias leinonen is a finnish professional ice hockey
topias leinonen is a finnish professional ice hockey goaltender who currently plays with jyp jyväskylä of the finnish liiga. leinonen was selected 41st overall by the buffalo sabres in the 2nd round of the 2022 nhl entry draft.
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3484ceda10d880afac770043d484218606bebca6
going into the 2022 nhl entry draft, leinonen
going into the 2022 nhl entry draft, leinonen was regarded as the top goaltending prospect and was ranked as the top european goalie by nhl central scouting. he was drafted 41st overall by the buffalo sabres, as the first goaltender selected in the 2022 nhl entry draft. he attended buffalo sabres development camp in 20...
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464e09bf448ba99b1df9633eec759ca349c98739
after playing for ilves in his youth, leinonen
after playing for ilves in his youth, leinonen moved to jyp 's under-16 program. he played for the jyp under-16 team in 2018-19, and the under-18 team in 2019-20. after playing 15 for the under-20 team in 2020-21, leinonen played 21 games for the under-20 team in the 2021-22 season and played 4 games in liiga for the s...
wikipedia
2799caac5d25ff85e85088219751bf70ca2981c2
topias leinonen (born 25 january 2004) is a
topias leinonen (born 25 january 2004) is a finnish professional ice hockey goaltender who currently plays with jyp jyväskylä of the finnish liiga. leinonen was selected 41st overall by the buffalo sabres in the 2nd round of the 2022 nhl entry draft.
wikipedia
768cdf9c22eb6158f317278146f286505f38f5b8
cristopher david moore, known as cris moore, is
cristopher david moore, known as cris moore, is an american computer scientist, mathematician, and physicist. he is resident faculty at the santa fe institute, and was formerly a full professor at the university of new mexico. he is an elected fellow of the american physical society, the american mathematical society, ...
wikipedia
64b9b6519bdc0ae9b33b702ef515943eeadadb51
in 2013, moore became the inaugural member of
in 2013, moore became the inaugural member of the zachary karate club. in 2014, moore was elected as a fellow of the american physical society for his fundamental contributions at the interface between nonlinear physics, statistical physics and computer science, including complex network analysis, phase transitions in ...
wikipedia
99f2a1a2634c21b40c555d5de0660820d339cefa
other topics in moore's research includemodeling undecidable problems
other topics in moore's research includemodeling undecidable problems by physical systems, phase transitions in random instances of the boolean satisfiability problem, the unlikelihood of success in the search for extraterrestrial intelligence due to the indistinguishability of advanced signaling technologies from rand...
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cf11f9da64d1905cace82bfebcb3b59781a414eb
moore has also been active in the field
moore has also been active in the field of network science, with many notable publications in the field. in work with aaron clauset, david kempe, and dimitris achlioptas, moore showed that the appearance of power laws in the degree distribution of networks can be illusory: network models such as the erdős–rényi model, ...
wikipedia
66f948358d1322b8249a1c894373965cc948c9f2
in 1993, moore found a novel solution to
in 1993, moore found a novel solution to the three-body problem, showing that it is possible in newtonian mechanics for three equal-mass bodies to follow each other around a shared orbit along a figure-eight shaped curve. moore's results were found through numerical computations, and they were made mathematically rigor...
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eaf2c9db2af362be8221268855cb457312439801
moore did his undergraduate studies at northwestern university,
moore did his undergraduate studies at northwestern university, graduating in 1986. he earned his ph.d. in 1991 from cornell university under the supervision of philip holmes. after postdoctoral studies at the santa fe institute, he joined the institute as a research faculty member in 1998, and moved to the university ...
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8eca477d724d274fe17ae46aa1329b5f06eada4d
cristopher david moore, known as cris moore, (born
cristopher david moore, known as cris moore, (born march 12, 1968, in new brunswick, new jersey) is an american computer scientist, mathematician, and physicist. he is resident faculty at the santa fe institute, and was formerly a full professor at the university of new mexico. he is an elected fellow of the american p...
wikipedia
242755d11aa78887b36712a31bfed3687acf046f
atsuto uchida is a japanese former professional footballer
atsuto uchida is a japanese former professional footballer who played as a right-back. uchida started his career with kashima antlers, making his debut in 2006 at the age of 17. after four years and three j1 league titles, uchida moved to germany with schalke 04 in 2010 for €1.3 million. with schalke, uchida won the 20...
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0155378168fc14c673ab22629b5109d7505832b5
in december 2008, uchida signed for an agency
in december 2008, uchida signed for an agency with tetsuro kiyooka, a fifa players' agent (sports agent), in hopes of moving to europe. it worked when he joined schalke 04 two years later after signing for tetsuro kiyooka. during his time at schalke 04, uchida lived in düsseldorf.
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888811a32201913a2f62c06fac9697f3f1fcdeaf
earlier in his football career, uchida said he
earlier in his football career, uchida said he was considering enrolling to university to obtain a teacher's license. in april 2016, uchida and his teammate yuya osako opened a football training facility in kashima. three years later in june, the pair released an exercise book. during his japan's career, teammate maya ...
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9d21baca2f379dcd1472fca2ff11f2efcc333392
outside of football, uchida provided the voice for
outside of football, uchida provided the voice for uschi, who is named after him, in the pokémon movie diancie and the cocoon of destruction. he does nor drink alcohol, preferring to drink banana juice. growing up, uchida said his favourite manga was captain tsubasa and supported júbilo iwata. since may 2015, uchida ha...
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fa16871ba3d67b03d3784a6aba7ca525abc583f2
outside of football, uchida is considered a massively
outside of football, uchida is considered a massively popular figure in his native country of japan. during a match against 1. fc nürnberg on 26 february 2011, 90 women from japan visited the veltins-arena to see uchida play, and his popularity has led to him being referred to as a japanese beckham. uchida's popularity...
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bff49e237bb73292a50d60ce8aafca4aec86acfb
expecting to be picked for the afc asian
expecting to be picked for the afc asian cup, uchida, however, was cut from the squad ahead of the tournament. it was revealed that he was recovering from his injury. uchida returned to the national side two months later, playing two times for the side.
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5ab5bf25a9324d3b67075a5ff0883b9376976aca
in may 2014, uchida was called up to
in may 2014, uchida was called up to the 2014 world cup squad. prior to this, uchida was involved in three friendly matches, which a game against cyprus on 27 may 2014, he scored his second international goal for the club. unlike the previous world cup, uchida started all three matches in the world cup, which saw japan...
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466f129b7ca1aebb8d5efed17016ed96a0e7273e
two years later, uchida was called up to
two years later, uchida was called up to the national side for the 2013 confederations cup squad. he was featured three times in the tournament, as japan loss all three matches and was eliminated in the group stage. at one point after losing to brazil, brazilian media gave uchida's performance the lowest score out of t...
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4b5ea849481dd77a5df8a8c4ee094ad19b8c2f2d
in december 2010, uchida was called up for
in december 2010, uchida was called up for the 2011 afc asian cup in qatar. he played all the first three matches in the tournament and helped japan reach the knockout stage. however, uchida was suspended for the quarter–final against qatar after being booked two times on different occasions. he returned to the startin...
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3576adf768b4423a0fc892d8da05b888b3d92392
in february 2010, uchida was called up to
in february 2010, uchida was called up to the national squad for the east asian football championship. he helped the side keep two clean sheets in the first two matches. however, japan's loss to south korea in matchday 3 meant that japan finished third place in the tournament. uchida was a member of the japan team for ...
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a485c016b0a286e89ea11caac0a936e9f9c3cf6e
uchida started 2009 when he set up two
uchida started 2009 when he set up two goals, in a 5–1 win against finland on 5 february 2009. in june 2009, he was featured in two of the three world cup qualifying matches, which resulted in japan qualified for the tournament. later in the year, uchida helped japan keep four clean sheets in a row between 10 october 2...
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7abcd9f04563023591bea92de5561b66423ef186
on two occasions between december 2007 and january
on two occasions between december 2007 and january 2008, uchida received an international call-up from national coach ivica osim but did not play any game. uchida finally made a full international debut for japan on 26 january 2008 in a friendly against chile at national olympic stadium in tokyo. this was the first mat...
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cc79ebc6e98336cfa1468c7c7bd55947126fd7b3
in july 2008, uchida was called up to
in july 2008, uchida was called up to japan u23 squad for the 2008 summer olympics. he played his first match of the tournament, starting the whole game, as japan u23 lost 1–0 against united states. uchida went on to make two appearances for the side in the tournament, as japan were eliminated in the group stage.
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3b51c5ba7544561a950b0dacbc6d55c51495d014
uchida also took part in the 2007 fifa
uchida also took part in the 2007 fifa u-20 world cup finals hosted by canada. he played his first match of the tournament and helped the side beat scotland 2–1. this was followed up by helping japan keep a clean sheet in the next two matches, which saw them go through to the knockout stage. however, the national side ...
wikipedia
5792a5bf2c58c89acef6cf0c3f4ae497eea401dd
uchida represented japan at several underage levels. uchida
uchida represented japan at several underage levels. uchida was part of the japan team for the 2006 afc youth championship finals hosted by india. he helped the japan's defence with two clean sheets in the first two matches in the group stage, which saw the side through to the knockout stage. uchida later helped japan ...
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576e78e7e61e97f50c7ebc8f10230cf5b46ccf15
at the start of the 2020 season, uchida
at the start of the 2020 season, uchida appeared as an unused substitute for the afc champions league against melbourne victory on 28 january 2020, as the club lost 1–0. shortly after, he suffered a calf injury during a friendly match against mito hollyhock on 1 february 2020, as kashima antlers won 1–0. after the matc...
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02026e0bbedb99f42e73a679f980ac5b43a94a87
ahead of the 2019 season, uchida was appointed
ahead of the 2019 season, uchida was appointed as the new kashima antlers’ captain following the departure of gen shoji. his first match as captain came on 1 march 2019 against kawasaki frontale and set up an equalising goal for sho ito, in a 1–1 draw. he later captained three more matches between 9 march 2019 and 30 m...
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b54cf25d7c1ca1512d86b61af3f15f6e087a8439
uchida made his first kashima antlers’ appearance in
uchida made his first kashima antlers’ appearance in eight years, starting a match and played 84 minutes, in a 0–0 draw against shimizu s-pulse in the opening game of the season. but he soon suffered a thigh injury that kept him out for a month. on 14 april 2018, uchida made his return from injury, starting a match and...
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d4250b9dcfc899b0e55aee674b10250155e045ec
on 2 january 2018, uchida re-joined j1 team
on 2 january 2018, uchida re-joined j1 team kashima antlers after playing seven and a half years in germany. uchida is scheduled to join his teammates in kashima on 9 january 2018, shortly before the start of the 2018 j1 season.
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ada48520b62798715beaa03d5c9215edfc502eb5
uchida made his union berlin debut on 10
uchida made his union berlin debut on 10 september 2017 in a 3–2 loss against fortuna düsseldorf. having been brought on as a substitute in the 75th minute he assisted for his club's temporary 2–1 lead three minutes later, an own goal by kaan ayhan. on 19 september, he made his first start in a 1–0 loss against sv sand...
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197e2ec727786e3b0ea0fd5fa2dbb0d7fbafe1e7
on 21 august 2017, uchida joined 2. bundesliga
on 21 august 2017, uchida joined 2. bundesliga side union berlin on a one-year contract. schalke allowed him to leave on a free transfer and "accommodated him financially" following his seven-year stay at the club.
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a855c63ad53cdfa69c84b9acfc0354b9b2df29f1
ahead of the 2016–17 season, uchida returned to
ahead of the 2016–17 season, uchida returned to training in the pre–season tour. however, his return to training was short–lived, as he suffered another injury once again. after suffering another injury in november, he made his first appearance in a year on 7 december 2016, in a 2–0 loss against red bull salzburg in th...
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7ce458a48357c9a03d32034b9c4ea593ccd5880c
however, ahead of the 2015–16 season, uchida undergone
however, ahead of the 2015–16 season, uchida undergone an operation on his patellar tendons, which saw him sidelined for six weeks. by october, he said he's recovering, though he hasn't confirm the date of his return. though he returned to training in january, uchida, however, suffered a knee injury that saw him out fo...
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c62cb9cd329baa9a0075b03b482efcb090a89d7d
however at the start of the 2014–15 season,
however at the start of the 2014–15 season, uchida suffered a patella tendon irritation. on 23 september 2014, he returned to the first team from injury, starting the whole game, in a 3–0 win over werder bremen. after the match, manager jens keller praised uchida's performance, saying: "great respect for uchida. he did...
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4340e1dce912ea7771b65933223443ef6b206c1c
in the 2013–14 season, uchida started in the
in the 2013–14 season, uchida started in the first two league matches before suffering a muscle injury, which he made a quick recovery. on 21 august 2013, he made his return from injury, starting the whole game, in a 1–1 draw against paok in the first leg of the uefa champions league play–offs round; after the match, g...
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69120f7f973b3555b2bddc181287b998e3e45357
ahead of the 2012–13 season, it was announced
ahead of the 2012–13 season, it was announced by the club that uchida signed a two-year professional contract extension to 30 june 2015. he was featured in the first two league matches before dropped in favour of benedikt höwedes. for the next two months, uchida returned to the starting line-up, playing in the right–ba...
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0c9aecbe74caff06038f23fbd3f838f9e70e5287
in the 2011–12 season, uchida appeared on the
in the 2011–12 season, uchida appeared on the substitute bench for the first three league matches and dfl-supercup, with marco höger preferred. he soon made his first appearance of the season for the side, playing in the left–back position, as schalke 04 lost 2–0 against hjk helsinki on 18 august 2011 in the first leg ...
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d8625a97bd27d69e2a536cda5d7936d3f7d70931
uchida made his schalke 04 debut, where he
uchida made his schalke 04 debut, where he played the whole game, in a 2–0 loss against bayern munich in the dfl-supercup. soon after, uchida made his league debut for the club in the opening game of the season, coming on as a second–half substitute for joël matip, in a 2–1 loss against hamburger sv. after being absent...
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fad1b0a5430eef584b3473cb3f60e56d945a0f0b
uchida made his schalke 04 debut, where he
12 march 2011, uchida wore a shirt which in response to the tōhoku earthquake and tsunami, saying: "dear friends in japan. hoping that many lives will be saved. let's stand together. this misfortune is very, very close to me. i keep in touch with japan." since returning to the first team, he managed to regain his first...
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57983ddabb6a4e1148e85abf772c4a46884b4b85
ahead of the 2010 season, uchida's performance continued
ahead of the 2010 season, uchida's performance continued to attract interests from european clubs. amid the transfer move, he helped the side win the japanese super cup after beating gamba osaka 5–3 on penalty shootout following the match being played throughout 120 minutes. at the start of the 2010 season, uchida cont...
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08cd4de53941f17eac1f1586c23c23b5136762c3
ahead of the 2009 season, uchida was linked
ahead of the 2009 season, uchida was linked a move away from kashima antlers, as several clubs from europe were interested in signing him. uchida started the season well when he helped the side beat gamba osaka 2–0 to win the japanese super cup. uchida set up a goal for marquinhos, in a 2–0 win over urawa red diamonds ...
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06e292cd3c4d059f0e03c7a420ca28fa788fd39b
ahead of the 2009 season, uchida was linked
, uchida returned to the starting line-up, in a 2–2 draw against kawasaki frontale on 15 july 2009. three days later on 18 july 2009, he made his 100th appearance for the side, in a 2–2 draw against shimizu s-pulse. his performance halfway through the season attracted interests from an unknown serie a clubs, who made a...
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dfc1035e253738bf17de39659095ac0280c92f57
uchida started the 2008 season when he started
uchida started the 2008 season when he started the whole game against sanfrecce hiroshima in the japanese super cup, as kashima antlers lost 4–3 on penalties after the game finished 2–2 throughout extra time. uchida also made his afc champions league debut, starting a match and played 76 minutes, in a 9–1 win against k...
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9a6ace6fb85b3d899c9b977bac46dd41c238b431
uchida started the 2008 season when he started
8, to help the side win the league for the second time. at the end of the 2008 season, where he made 34 appearances and scoring once in all competitions, uchida was named j. league best eleven for the first time. in addition, uchida signed a contract extension, keeping him until 2012.
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9bb1cf3458e91ce36c5cbd15079a4215b021073a
in the 2007 season, uchida continued to regain
in the 2007 season, uchida continued to regain his first team place for the side, playing in the right–back position. he later helped the club win the league for the first time since after beating shimizu s-pulse 3–0 in the last game of the season to regain the club's nine consecutive wins. in the final of the emperor ...
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5baa163655e5b96c2cbab06aa6003f6724687322
on 5 march 2006, uchida began his professional
on 5 march 2006, uchida began his professional career when he debuted for kashima at the age of 17 in the season-opener against sanfrecce hiroshima, since which he has remained a fixture in the starting eleven. his first goal as a professional footballer came on 21 march 2006 when he scored against ventforet kofu. sinc...
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870ac8acdbe1d47ad5fa7d0996272aa3e88ddec4
born in kannami, shizuoka, japan, uchida was educated
born in kannami, shizuoka, japan, uchida was educated at and played for shimizu higashi high school. during his time there, he played mainly in the wing position, partly because of his speed. the school's director kazuo umeda switched uchida's position to the right–back position, in which he plays today. in 2006, uchid...
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03457460f11c5a2dc7b120b490da543864c7da11
uchida made his first appearance for the japan
uchida made his first appearance for the japan national team in january 2008, and went on to make 74 appearances for his country, representing them in the 2011 afc asian cup, the 2013 fifa confederations cup and the 2014 fifa world cup, as well as scoring two goals.
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47b94820000e27e078d437c1bb897c9b5b3e77de
uchida started his career with kashima antlers, making
uchida started his career with kashima antlers, making his debut in 2006 at the age of 17. after four years and three j1 league titles, uchida moved to germany with schalke 04 in 2010 for €1.3 million. with schalke, uchida won the 2010–11 dfb-pokal, and was named in the bundesliga team of the season twice between 2012 ...
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f30807d29b3c50f3be75bb6596b50f51e9f35d64
alexander guskov is a russian former professional ice
alexander guskov is a russian former professional ice hockey defenceman. he was selected by the columbus blue jackets in the 7th round of the 2003 nhl entry draft. with a career spanning over 20 years, guskov between 2007 and 2017 played as a journeyman for multiple teams in the russian superleague (rsl) and then the k...
wikipedia
887302321e8c7594d6d8e9359df6e920ee6245f2
alexander guskov (born november 26, 1976) is a
alexander guskov (born november 26, 1976) is a russian former professional ice hockey defenceman. he was selected by the columbus blue jackets in the 7th round (200th overall) of the 2003 nhl entry draft.
wikipedia
7bc17e924b38af8a6de9cb9a573bae2630090746
3α-hydroxysteroid dehydrogenase (3α-hsd) is an enzyme (1.1.1.50) that
3α-hydroxysteroid dehydrogenase (3α-hsd) is an enzyme (1.1.1.50) that plays a role in the metabolism of steroids and non-steroidal compounds in humans and other species, such as bacteria, fungi, plants, and so on. this enzyme catalyzes the chemical reaction of conversion of 3-ketosteroids into 3α-hydroxysteroids. the e...
wikipedia
dcade817903cf9309bf3e6779e318934c5f29581
in non-human species, 3α-hydroxysteroid dehydrogenases contribute to steroidogenesis
in non-human species, 3α-hydroxysteroid dehydrogenases contribute to steroidogenesis as part of the nadph/nad±dependent oxidoreductase family; so that these enzymes facilitate the conversion between ketones and their corresponding secondary alcohols across various positions on steroidal substrates (3α-, 3β-, 11β-, 17β-...
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111fa2739a479eba578bbe21f12b125a1bb374ab
regardless of a particular isoform, the 3α-hydroxysteroid dehydrogenase
regardless of a particular isoform, the 3α-hydroxysteroid dehydrogenase enzyme in humans is known to be necessary for the synthesis of many important endogenous neurosteroids, such as allopregnanolone, tetrahydrodeoxycorticosterone, and 5α-androstane-3α,17β-diol, also known as 3α-androstanediol, and abbreviated as 3α-d...
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73b97c19f7a4d7413c8de17b7251ed54654a09c3
in humans, 3α-hydroxysteroid dehydrogenase is encoded by the
in humans, 3α-hydroxysteroid dehydrogenase is encoded by the multiple different genes, so that each gene encodes a particular isoform. the most studied isoforms are type 1 (akr1c4), type 2 (akr1c3) and type 3 (akr1c2). each of these isoforms shares higher than 70% sequence homology and common properties. they are monom...
wikipedia
ba59aa13d8902ac000427bcacb289ce0a8d2da64
in humans, 3α-hydroxysteroid dehydrogenase is encoded by the
reduced form), so that nad plays a role in the production of energy through the electron transport chain, as well as in the synthesis of nucleic acids. in context of 3α-hydroxysteroid dehydrogenase enzymes, the notion that these enzymes are nad±specific mean that they require nad in either its oxidized or reduced form ...
wikipedia
7bc17e924b38af8a6de9cb9a573bae2630090746
3α-hydroxysteroid dehydrogenase (3α-hsd) is an enzyme (1.1.1.50) that
3α-hydroxysteroid dehydrogenase (3α-hsd) is an enzyme (1.1.1.50) that plays a role in the metabolism of steroids and non-steroidal compounds in humans and other species, such as bacteria, fungi, plants, and so on. this enzyme catalyzes the chemical reaction of conversion of 3-ketosteroids into 3α-hydroxysteroids. the e...
wikipedia
1608dd55bae506d0e84cd7525651fdc7b2f08c7d
in the fourth round, dukla faced another second
in the fourth round, dukla faced another second league team, being paired with Ústí nad labem. dukla won both matches of the two-legged tie by a 3–0 scoreline, going through 6–0 on aggregate. at the quarter-final stage, the home game against fellow first league team fk jablonec finished goalless. the return leg, two we...
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ac0fc4e4f331811d46d57aadd4feafddff344856
as a first league team, dukla entered the
as a first league team, dukla entered the cup at the second round stage. in the second round, dukla faced fourth division side neratovice–byškovice, winning 4–0 away from home. the third round match against fc mas táborsko of the second league was a closer game; goals from lukáš Štetina and tomáš přikryl helped dukla t...
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f2ef75d3e6a85a739cc23fa8c8ad554baecb17cf
low-energy electron diffraction (leed) is a technique for
low-energy electron diffraction (leed) is a technique for the determination of the surface structure of single-crystalline materials by bombardment with a collimated beam of low-energy electrons (30–200 ev) and observation of diffracted electrons as spots on a fluorescent screen. leed may be used in one of two ways: qu...
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aa3f82b3a1f71325655548c17734a296725aec81
quantitatively, where the intensities of diffracted beams are
quantitatively, where the intensities of diffracted beams are recorded as a function of incident electron beam energy to generate the so-called i–v curves. by comparison with theoretical curves, these may provide accurate information on atomic positions on the surface at hand.
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6e2876008f124c7ee7b1f7c8bc355f5264fd7f70
although some degree of spot profile analysis can
although some degree of spot profile analysis can be performed in regular leed and even leem setups, dedicated spa-leed setups, which scan the profile of the diffraction spot over a dedicated channeltron detector allow for much higher dynamic range and profile resolution.
wikipedia
5699dd76ab129d8afea548b445afbab6d8305ddf
spa-leed is a technique where the profile and
spa-leed is a technique where the profile and shape of the intensity of diffraction beam spots is measured. the spots are sensitive to the irregularities in the surface structure and their examination therefore permits more-detailed conclusions about some surface characteristics. using spa-leed may for instance permit ...
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536725280803ad598391f201b56a60b034f55acf
a real surface is not perfectly periodic but
a real surface is not perfectly periodic but has many imperfections in the form of dislocations, atomic steps, terraces and the presence of unwanted adsorbed atoms. this departure from a perfect surface leads to a broadening of the diffraction spots and adds to the background intensity in the leed pattern.
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22c50523c14a1b108ee3840092afafe5654dab66
tensor leed is an attempt to reduce the
tensor leed is an attempt to reduce the computational effort needed by avoiding full leed calculations for each trial structure. the scheme is as follows: one first defines a reference surface structure for which the i–v spectrum is calculated. next a trial structure is created by displacing some of the atoms. if the d...
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5a2dd0f5de39a4fc5613a39982b6b027ea879287
in leed the exact atomic configuration of a
in leed the exact atomic configuration of a surface is determined by a trial and error process where measured i–v curves are compared to computer-calculated spectra under the assumption of a model structure. from an initial reference structure a set of trial structures is created by varying the model parameters. the pa...
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5a46b0d4daeaee3bce3fb95517dfc6253198d68c
a common approach in leed calculations is to
a common approach in leed calculations is to describe the scattering potential of the crystal by a "muffin tin" model, where the crystal potential can be imagined being divided up by non-overlapping spheres centered at each atom such that the potential has a spherically symmetric form inside the spheres and is constant...
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a common method to achieve this is the
a common method to achieve this is the self-consistent multiple scattering approach. one essential point in this approach is the assumption that the scattering properties of the surface, i.e. of the individual atoms, are known in detail. the main task then reduces to the determination of the effective wave field incide...
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cd14d9cbb5f9a9860dccef43d2f4a5aa2b995b2a
the term dynamical stems from the studies of
the term dynamical stems from the studies of x-ray diffraction and describes the situation where the response of the crystal to an incident wave is included self-consistently and multiple scattering can occur. the aim of any dynamical leed theory is to calculate the intensities of diffraction of an electron beam imping...
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57301d0e6cb112d2d7fa01aca85617c38b14a0f0
where y (e) = l − 1 /
where y (e) = l − 1 / (l − 2 + v o i 2) {\displaystyle y(e)=l^{-1}/(l^{-2}+v_{oi}^{2})} and v o i {\displaystyle v_{oi}} is the imaginary part of the electron self-energy. in general, r p ≤ 0.2 {\displaystyle r_{p}\leq 0.2} is considered as a good agreement, r p ≃ 0.3 {\displaystyle r_{p}\simeq 0.3} is considered medio...
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67d7ce74f873f72fd04c58e0cf81fbc90bb0707d
a more quantitative analysis of leed experimental data
a more quantitative analysis of leed experimental data can be achieved by analysis of so-called i–v curves, which are measurements of the intensity versus incident electron energy. the i–v curves can be recorded by using a camera connected to computer controlled data handling or by direct measurement with a movable far...
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271809c44ad04d209109eaf265d0c8a91d1a5b9f
the inspection of the leed pattern gives a
the inspection of the leed pattern gives a qualitative picture of the surface periodicity i.e. the size of the surface unit cell and to a certain degree of surface symmetries. however it will give no information about the atomic arrangement within a surface unit cell or the sites of adsorbed atoms. for instance, when t...
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44eb2ce09ced8094a757502c473854f8d094a240
figure 8 shows the superposition of the diffraction
figure 8 shows the superposition of the diffraction patterns for the two orthogonal domains (2×1) and (1×2) on a square lattice, i.e. for the case where one structure is just rotated by 90° with respect to the other. the (1×2) structure and the respective leed pattern are shown in figure 7. it is apparent that the loca...
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however, since the average domain size is generally
however, since the average domain size is generally larger than the coherence length of the probing electrons, interference between electrons scattered from different domains can be neglected. therefore, the total leed pattern emerges as the incoherent sum of the diffraction patterns associated with the individual doma...
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d8c2f6243174131dba9a9ad4ca098cff46ae0b71
an essential problem when considering leed patterns is
an essential problem when considering leed patterns is the existence of symmetrically equivalent domains. domains may lead to diffraction patterns that have higher symmetry than the actual surface at hand. the reason is that usually the cross sectional area of the primary electron beam (~1 mm) is large compared to the ...
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84a727778a968394f1740250006728b07b68d111
for a commensurate superstructure the symmetry and the
for a commensurate superstructure the symmetry and the rotational alignment with respect to adsorbent surface can be determined from the leed pattern. this is easiest shown by using a matrix notation, where the primitive translation vectors of the superlattice { a, b } are linked to the primitive translation vectors of...
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3d8db1f542ebd4c54c7aa98aa98efc7d0167695e
overlaying superstructures on a substrate surface may introduce
overlaying superstructures on a substrate surface may introduce additional spots in the known (1×1) arrangement. these are known as extra spots or super spots. figure 6 shows many such spots appearing after a simple hexagonal surface of a metal has been covered with a layer of graphene. figure 7 shows a schematic of re...
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e97ed135a8e8b4ac05bc79830b88df0bb855552b
figure 4 shows the ewald's sphere for the
figure 4 shows the ewald's sphere for the case of normal incidence of the primary electron beam, as would be the case in an actual leed setup. it is apparent that the pattern observed on the fluorescent screen is a direct picture of the reciprocal lattice of the surface. the spots are indexed according to the values of...
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b25a0d0b63d72521866b83bf6d143c12d45cd07a
the laue-condition equation can readily be visualized using
the laue-condition equation can readily be visualized using the ewald's sphere construction.figures 3 and 4 show a simple illustration of this principle: the wave vector k i {\displaystyle \mathbf {k} _{i}} of the incident electron beam is drawn such that it terminates at a reciprocal lattice point. the ewald's sphere ...
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321419a7e2a8084eebb67105a64af49a5f3b452a
where a ∗ {\displaystyle \mathbf {a} ^{*}} and
where a ∗ {\displaystyle \mathbf {a} ^{*}} and b ∗ {\displaystyle \mathbf {b} ^{*}} are the primitive translation vectors of the 2d reciprocal lattice of the surface and k f ∥ {\displaystyle {\textbf {k}}_{f}^{\parallel }}, k i ∥ {\displaystyle {\textbf {k}}_{i}^{\parallel }} denote the component of respectively the re...
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954000757cffdfa8cfc66d9dc0f8f40ca51585cc
is a vector of the reciprocal lattice. note
is a vector of the reciprocal lattice. note that these vectors specify the fourier components of charge density in the reciprocal (momentum) space, and that the incoming electrons scatter at these density modulations within the crystal lattice. the magnitudes of the wave vectors are unchanged, i.e. | k f | = | k i | {\...
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a1e09c81abdbf670313ec30027b012bd14da9db5
for an incident electron with wave vector k
for an incident electron with wave vector k i = 2 π / λ i {\displaystyle \mathbf {k} _{i}=2\pi /\lambda _{i}} and scattered wave vector k f = 2 π / λ f {\displaystyle \mathbf {k} _{f}=2\pi /\lambda _{f}}, the condition for constructive interference and hence diffraction of scattered electron waves is given by the laue ...
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c0340fc1caec3c3a9c902ef313b80b4ed8242759
kinematic diffraction is defined as the situation where
kinematic diffraction is defined as the situation where electrons impinging on a well-ordered crystal surface are elastically scattered only once by that surface. in the theory the electron beam is represented by a plane wave with a wavelength given by the de broglie hypothesis:
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07355d18488d6de2e7771c1a527093d3f3c782ac
here d is the penetration depth, and Λ
here d is the penetration depth, and Λ (e) {\displaystyle \lambda (e)} denotes the inelastic mean free path, defined as the distance an electron can travel before its intensity has decreased by the factor 1/ e. while the inelastic scattering processes and consequently the electronic mean free path depend on the energy,...
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5e3a3eb09249021ce04ffe4d6ccda4b4e0ff4a62
the basic reason for the high surface sensitivity
the basic reason for the high surface sensitivity of leed is that for low-energy electrons the interaction between the solid and electrons is especially strong. upon penetrating the crystal, primary electrons will lose kinetic energy due to inelastic scattering processes such as plasmon and phonon excitations, as well ...
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12a9ceda7fe480f312216b1df13d28f277c451af
a modern data acquisition system usually contains a
a modern data acquisition system usually contains a ccd/cmos camera pointed to the screen for diffraction pattern visualization and a computer for data recording and further analysis. more expensive instruments have in-vacuum position sensitive electron detectors that measure the current directly, which helps in the qu...
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5e808a08cdec5cb7564b348e27bebe0b29526a5e
leed optics is in some instruments also used
leed optics is in some instruments also used for auger electron spectroscopy. to improve the measured signal, the gate voltage is scanned in a linear ramp. an rc circuit serves to derive the second derivative, which is then amplified and digitized. to reduce the noise, multiple passes are summed up. the first derivativ...
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bcfd2653c3e8f2c496292e8f77fe7994b4d54c6b
often the annealing process will let bulk impurities
often the annealing process will let bulk impurities diffuse to the surface and therefore give rise to a re-contamination after each cleaning cycle. the problem is that impurities that adsorb without changing the basic symmetry of the surface, cannot easily be identified in the diffraction pattern. therefore, in many l...
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acefd8217f254eb9abc46eec11bb299d59938c51
the sample of the desired surface crystallographic orientation
the sample of the desired surface crystallographic orientation is initially cut and prepared outside the vacuum chamber. the correct alignment of the crystal can be achieved with the help of x-ray diffraction methods such as laue diffraction. after being mounted in the uhv chamber the sample is cleaned and flattened. u...
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d66b9e2ed044e9f783ed25efdda66323d4eeeeae
it soon became clear that the kinematic (single-scattering)
it soon became clear that the kinematic (single-scattering) theory, which had been successfully used to explain x-ray diffraction experiments, was inadequate for the quantitative interpretation of experimental data obtained from leed. at this stage a detailed determination of surface structures, including adsorption si...
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c9712c049134d3da758e9538617d8dcb2b2b813f
in the early 1960s leed experienced a renaissance,
in the early 1960s leed experienced a renaissance, as ultra-high vacuum became widely available, and the post acceleration detection method was introduced by germer and his coworkers at bell labs using a flat phosphor screen. using this technique, diffracted electrons were accelerated to high energies to produce clear ...
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nonetheless, h. e. farnsworth and coworkers at brown
nonetheless, h. e. farnsworth and coworkers at brown university pioneered the use of leed as a method for characterizing the absorption of gases onto clean metal surfaces and the associated regular adsorption phases, starting shortly after the davisson and germer discovery into the 1970s.
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c66888fadc9d09cf4c33c3598eba7aae70859762
though discovered in 1927, low-energy electron diffraction did
though discovered in 1927, low-energy electron diffraction did not become a popular tool for surface analysis until the early 1960s. the main reasons were that monitoring directions and intensities of diffracted beams was a difficult experimental process due to inadequate vacuum techniques and slow detection methods su...
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346b3dc0f2815aaa89063949a386cd27ea09fffa
davisson and germer published notes of their electron-diffraction
davisson and germer published notes of their electron-diffraction experiment result in nature and in physical review in 1927. one month after davisson and germer's work appeared, thompson and reid published their electron-diffraction work with higher kinetic energy (thousand times higher than the energy used by davisso...
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4ee67eff5b793eece17334dc133a73d3b914392f
the theoretical possibility of the occurrence of electron
the theoretical possibility of the occurrence of electron diffraction first emerged in 1924, when louis de broglie introduced wave mechanics and proposed the wavelike nature of all particles. in his nobel-laureated work de broglie postulated that the wavelength of a particle with linear momentum p is given by h / p, wh...
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627ead699f333bf23f120a2e446f6b7e96202851
low-energy electron diffraction (leed) is a technique for
low-energy electron diffraction (leed) is a technique for the determination of the surface structure of single-crystalline materials by bombardment with a collimated beam of low-energy electrons (30–200 ev) and observation of diffracted electrons as spots on a fluorescent screen.
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