AcharyaChanakya/simple-wikipedia huggingface dataset:
Dagestan has the status of "republic" in Russia and has its own constitution and official languages. Republics in Russia are the home of its ethnic minorities (those who are not Russians), and usually one or two nationalities have a majority of the population in each republic. But in Dagestan, there are over 30 different nationalities (the largest of which are the Avar, Lak, Dargwa, Lezgian, and Tabasaran), and none of these form a majority. This is because the mountains in the region make it hard for people to move around. These people speak 30 different languages, but use Russian as their lingua franca to communicate between each other.
Most people of Dagestan are Muslims and belong to the Shafi`i school of Sunni Islam.
Theoretical chemistry
Theoretical chemistry tries to explain data from chemistry experiments. It uses mathematics and computers. Theoretical chemistry predicts what happens when atoms combine to form molecules. It also predicts chemical properties (characteristics) of molecules. An important part of theoretical chemistry is quantum chemistry. This is using quantum mechanics to understand valency (the number of bonds formed by an atom of an element). Other important parts include molecular dynamics, statistical thermodynamics and theories of electrolyte solutions, reaction networks, polymerization and catalysis.
Theoretical chemists use a wide range of tools. These tools include analytical models (for example, LCAO-MOs to approximate the behaviors of electrons in molecules) and computational and numerical simulations.
Theorists in chemistry create theoretical models. Then, they find things that experimental chemists can measure from those models. This helps chemists to look for data that can prove a model not true. The data helps to chose between several different or opposite models.
Theorists also try to generate or modify models to fit any new data, If the data can not fit the model, chemists try to make the smallest change to the model to fit the data. In some cases, chemists throw out a model if a lot of data will not fit, over time.
Theoretical chemistry uses physics to explain or predict chemical observations. In recent years, it has been mainly about quantum chemistry (the application of quantum mechanics to problems in chemistry). The main parts of theoretical chemistry are electronic structure, dynamics, and statistical mechanics.
All of these areas are used in the process of predicting chemical reactivities. Other less central research areas include the mathematical description of bulk chemistry in various phases. Theoretical chemists want to explain chemical kinetics (the pathway that molecules combine).
Scientists call a lot of this work "computational chemistry". Computational chemistry usually uses theoretical chemistry to work on industrial and practical problems. Examples of computational chemistry are projects to approximate chemical measurements such as certain types of post Hartree-Fock, Density Functional Theory, semiempirical methods (such as PM3) or force field methods. Some chemical theorists use statistical mechanics to create a link between the microscopic phenomena of the quantum world and the macroscopic bulk properties of systems.
Historically, researchers use theoretical chemistry to study:
A pebble is a piece of rock with a particle size of 4 to 64 millimetres. They are often made of flint.
Pebbles are larger than granules (2 to 4 millimetres diameter) and smaller than cobbles (64 to 256 millimetres diameter). A rock made predominantly of pebbles is termed a conglomerate. Pebble tools are among the earliest known man-made artifacts, dating from the Palaeolithic period of human history.
A beach composed chiefly of surface pebbles is commonly termed a shingle beach. This type of beach resists wave erosion, and has ecological niches which can provide habitat for animals and plants.
MESSENGER
MESSENGER, MErcury Surface, Space ENvironment, GEochemistry and Ranging, was an unmanned NASA and APL spacecraft. It was orbiting and studying the planet Mercury. Its mission lasted 10 years, 8 months and 28 days.
It was launched on August 3, 2004 at Cape Canaveral Air Force Station. It was aboard a Boeing Delta II rocket. After launch, the probe did several fly-bys and deep space manoeuvres to gain the right trajectory and speed.
It completed 30% mapping of Mercury on January 14, 2008. MESSENGER made one more pass by Mercury in 2009, and on March 18, 2011 began to orbit Mercury. 100% mapping was completed in March 2013 and the probe continued its studies. On April 30, 2015, it crashed into Mercury. It crashed near the crater Janáček.
Compensation (psychology)
In psychology, compensation is a way people hide something that they cannot do well, by doing something else really well. They may not even be aware that they are doing it. Compensation can hide real or imagined problems and personal or physical inferiority. However it does not really solve the cause of the problem. Positive compensations may help a person overcome difficulties. But negative compensations do not, and can even make the problems worse.
There are two kinds of negative compensation:
A well-known example of failing overcompensation, can be seen in people going through a mid life crisis. Approaching midlife many people (especially men) lack the energy to maintain their psychological defenses, including their compensatory acts.
Alfred Adler, founder of individual psychology, used the word compensation in relation inferiority feelings. In his book "Study of Organ Inferiority and Its Physical Compensation" (1907) he wrote if a person feels inferior (weak) then they will (usually) try to compensate for it somewhere else.
Adler's reason to explore this was from his own experience. He was shy and yet he pushed himself to give lectures.
Adler also "transferred" this idea of compensation to psychic training.
Narcissistic people, by compensation theory, hide their feelings of low self-esteem by:
Narcissistic children try to compensate for their jealousy and anger by fantasizing about:
Christopher Lasch, an American historian and social critic wrote in his book "The Culture of Narcissism" (1979) that North American society in the 1970s was narcissistic. The narcissistic society:
Therefore, it is "fascinated" with fame.
Consumption can be an example of compensation (see study by Allison J. Pugh: "From compensation to ‘childhood wonder’"). Examples:
Shingle beach
A shingle beach (or pebble beach) is a beach made of pebbles, not sand. The stones may be from diameter. These beaches strongly resist erosion by waves.
This beach landform is quite common in Western Europe, because the pebbles come from the lines of flint in the chalk. Chesil Bank is an example. When the chalk erodes, the tough flint stays as pebbles.
Other examples are found in Bahrain, North America and in a number of other places. On the east coast of New Zealand's South Island, there are mixed shingle and sand fans in the braided rivers.
Puddingstone
Puddingstone is a kind of sedimentary rock. It is formed when pebbles, perhaps from a shingle beach, are cemented together by silica coming out of solution.
The rock which forms is extremely hard and resistant to wear. It is used for grindstones and building. The pebbles are usually made of flint, and both they and the matrix are made of silica.
Eponym
An eponym is a person's name that is used to name something else. This is common in science, such as asteroid, politics and medicine.
Injective function
In mathematics, a injective function is a function "f" : "A" → "B" with the following property. For every element "b" in the codomain "B", there is at most one element "a" in the domain "A" such that "f"("a")="b", or equivalently, distinct elements in the domain map to distinct elements in the codomain.
The term "injection" and the related terms "surjection" and "bijection" were introduced by Nicholas Bourbaki. In the 1930s, he and a group of other mathematicians published a series of books on modern advanced mathematics.
An injective function is often called a 1-1 (read "one-to-one") function. However, this is to be distinguish from a 1-1 correspondence, which is a bijective function (both injective and surjective).
Formally:
The element formula_5 is called a pre-image of the element formula_6 if formula_7 . Injections have one or none pre-images for every element "b" in "B".
Cardinality is the "number" of elements in a set. The cardinality of "A"={X,Y,Z,W} is 4. This is written as #"A"=4.
If the cardinality of the codomain is less than the cardinality of the domain, then the function cannot be an injection. For example, there is no injection from 6 elements to 5 elements, since it is impossible to map 6 elements to 5 elements without a duplicate.
Let "f"("x"):ℝ→ℝ be a real-valued function "y"="f"("x") of a real-valued argument "x". (This means both the input and output are real numbers.)
Example: The linear function of a slanted line is 1-1. That is, "y"="ax"+"b" where "a"≠0 is an injection. (It is also a surjection and thus a bijection.)
Example: The polynomial function of third degree: "f"("x")="x" is an injection. However, the polynomial function of third degree: "f"("x")="x" –3x is not an injection.
Example: The quadratic function "f"("x") = "x" is not an injection.
Note: One can make a non-injective function into an injective function by eliminating part of the domain. We call this restricting the domain. For example, restrict the domain of "f"("x")="x"² to non-negative numbers (positive numbers and zero). Define
This function is now an injection. (See also restriction of a function.)
Example: The exponential function "f"("x") = 10 is an injection. (However, it is not a surjection.)
Note: The fact that an exponential function is injective can be used in calculations.
Example: The logarithmic function base 10 "f"("x"):<nowiki>(0,+∞)</nowiki>→ℝ defined by "f"("x")=log("x") or "y"=log("x") is an injection (and a surjection). (This is the inverse function of 10.)
Example: The function "f":ℕ→ℕ that maps every natural number "n" to "2n" is an injection. Every even number has exactly one pre-image. Every odd number has no pre-image.
Lorient
Lorient is a commune and seaport in the Morbihan department in Brittany.
Lorient is twinned with:
Bongo may mean:
Surjective function
In mathematics, a surjective or onto function is a function "f" : "A" → "B" with the following property. For every element "b" in the codomain "B", there is at least one element "a" in the domain "A" such that "f"("a")="b". This means that no element in the codomain is unmapped, and that the range and codomain of "f" are the same set.
The term "surjection" and the related terms "injection" and "bijection" were introduced by the group of mathematicians that called itself . In the 1930s, this group of mathematicians published a series of books on modern advanced mathematics. The French prefix "sur" means "above" or "onto" and was chosen since a surjective function maps its domain on to its codomain.
where the element formula_4 is called the image of the element formula_5, and the element formula_5 a pre-image of the element formula_4.
The formal definition can also be interpreted in two ways:
A pre-image does "not" have to be unique. In the top image, both {X} and {Y} are pre-images of the element {1}. It is only important that there be at least one pre-image.
Let "f"("x"):ℝ→ℝ be a real-valued function "y"="f"("x") of a real-valued argument "x". (This means both the input and output are numbers.)
Finding a pre-image "x" for a given "y" is equivalent to either question:
In mathematics, we can find exact (analytic) roots only of polynomials of first, second (and third) degree. We find roots of all other functions approximately (numerically). This means a formal proof of surjectivity is rarely direct. So the discussions below are informal.
Example: The linear function of a slanted line is "onto". That is, "y"="ax"+"b" where "a"≠0 is a surjection. (It is also an injection and thus a bijection.)
Example: The cubic polynomial (of third degree) "f"("x")="x"-3"x" is a surjection.
Example: The quadratic function "f"("x") = "x" is not a surjection. There is no "x" such that "x" = −1. The range of "x"² is <nowiki>[0,+∞) </nowiki>, that is, the set of non-negative numbers. (Also, this function is not an injection.)
Note: One can make a non-surjective function into a surjection by "restricting" its codomain to elements of its range. For example, the "new" function, "f"("x"):ℝ → [0,+∞) where "f"("x") = "x" is a surjective function. (This is not the same as the restriction of a function which restricts the domain!)
Example: The exponential function "f"("x") = 10 is not a surjection. The range of "10" is (0,+∞), that is, the set of positive numbers. (This function is an injection.)
Example: The logarithmic function base 10 "f"("x"):<nowiki>(0,+∞)</nowiki>→ℝ defined by "f"("x")=log("x") or "y"=log("x") is a surjection (and an injection). (This is the inverse function of 10.)
Example: The function "f"(("x","y")):ℝ²→ℝ defined by "z"="y" is a surjection. Its graph is a plane in 3-dimensional space. The pre-image of "z" is the line y="z" in the "x"0"y" plane.
Range (mathematics)
In mathematics, the range is a concept which has various meanings in different topics:
Organic reaction
Shikasta (novel)
Shikasta is a 1979 science fiction novel. The full title is Re: Colonised Planet 5, Shikasta. British Nobel Prize in Literature-winner Doris Lessing wrote it as the first book in her five-book "Canopus in Argos" series. Alfred A. Knopf published it first in the United States in October 1979. Jonathan Cape published the book in the United Kingdom in November 1979. Shikasta is also the name of the fictional planet featured in the novel.
The book has a subtitle, ""Personal, psychological, historical documents relating to visit by Johor (George Sherban) Emissary (Grade 9) 87th of the Period of the Last Days"". 'The novel is the history of the planet Shikasta under the influence of three galactic empires: Canopus, Sirius, and their shared enemy, Puttiora. The book is a series of reports by Canopean visitors to Shikasta. They record what happens on the planet which is very similar to Earth. The novel shows the Earth's prehistory, how things became worse, the "Century of Destruction" (the 20th-century), and the Apocalypse (World War III).
"Shikasta" uses stories and images from the Old Testament and is influenced by spiritual and mystical themes in Sufism. Lessing had become interested in this Islamic belief system in the mid-1960s. The book was a major shift of focus in Lessing's writing, from realism to science fiction. Many of her readers were unhappy with the change. Critics gave the book both good and bad reviews. Some were impressed by the way the book showed a wide view of humanity and the universe. One reviewer called it a brave "and disturbing work from one of the world's great living writers". Others reviewers disliked the novel because it was depressing and humanity had no free will. People's lives were controlled by galactic empires.
The story of Shikasta is retold in the third book of the "Canopus" series, "The Sirian Experiments" (1980). In that book, the story is told from the point of view of Sirius. Shikasta appears again in the fourth book in the series, "The Making of the Representative for Planet 8" (1982). The Zones that are briefly mentioned in "Shikasta" are the subject of the second book in the series, "The Marriages Between Zones Three, Four and Five" (1980).
HOMO/LUMO
HOMO stands for highest occupied molecular orbital. LUMO stands for lowest unoccupied molecular orbital. The energy difference between the HOMO and LUMO is termed the HOMO-LUMO gap. HOMO and LUMO are sometimes referred to as frontier orbitals.
Each molecular orbital has a calculated energy level. Chemists sort the molecular orbitals (MOs) by energy levels. Chemists assume that the electrons will occupy the lowest energy level MOs first. For example, if a molecule has enough electrons to fill 15 MOs, the 15 MOs with the lowest energy levels will be occupied. The 15th MO on the list would be called the "highest occupied molecular orbital" (HOMO) and the 16th MO on the list would be the "lowest unoccupied molecular orbital" (LUMO). The difference in the HOMO's energy level and the LUMO's energy level is called the band gap. The band gap can sometimes serve as a measure of the excitability of the molecule: the smaller the energy, the more easily a molecule's electrons will be excited. For example, this can help predict whether a substance will have luminescence.
A SOMO is a "singly occupied molecular orbital" such as half-filled HOMO of a radical.
Roald Hoffmann
Roald Hoffmann (born July 18, 1937) is a Polish-born American theoretical chemist of Jewish descent. He won the 1981 Nobel Prize in Chemistry. He currently teaches at Cornell University in Ithaca, New York.
He was born in Zloczov, Poland (now Ukraine)
Hoffmann survived The Holocaust and moved to the United States in 1949.
Substituent
In organic chemistry and biochemistry, substituent is the name for a single atom or for a group of atoms that take the position of another atom in a molecule. They replace this atom. This reaction is called a substitution reaction. The atom or group of atoms that gets replaced is called the leaving group.
The terms substituent, side chain, group, branch, or pendant group are used in the same way to describe branches from a parent structure. These terms have different meanings in polymer chemistry. In polymers, side chains extend from a backbone structure, while they are attached to the alpha carbon atoms of the amino acid backbone in proteins.
Organic chemistry has rules for naming compounds with substituent groups. The substituent group is listed first with a suffix to describe how it is attached to the main carbon chain. The suffix -yl is used when naming organic compounds that contain a single bond replacing one hydrogen. -ylidene and -ylidyne are used for double bonds and triple bonds respectively. When naming hydrocarbons that contain a substituent, position numbers may be used. These number will indicate which carbon atom the substituent is attached to. One case where this information is needed is that of isomers.
The phrases most-substituted and least-substituted are often used to describe molecules and predict their products. For example:
In a structural diagram or formula, the letters R or X are used to represent a substituent group. An organic substituent such as methyl, ethyl, aryl can be written as R (or R, R, etc.) This is a generic placeholder. The "R" derived from "radical" or "rest". The R can represent as many atoms as the author wants. The first to use this symbol was Charles Frédéric Gerhardt in 1844.
The symbol X can represent electronegative substituents such as the halides.
Greater rhea
The greater rhea, "Rhea americana", is a flightless bird found in South America. The greater rhea is also known as grey, common rhea, or the American rhea. The species, first described by Carl Linnaeus in 1758, is found in Argentina, Bolivia, Brazil, Paraguay, and Uruguay.
The greater rhea takes its scientific name from the Greek goddess Rhea and the Latin word for "America".
It has a length of and a wingspan of . Weighing , the greater rhea is the largest bird in South America.
Petr Kalandra
Petr Kalandra (March 10, 1950 – September 7, 1995) was a Czech musician, guitarist, harmonica player, vocalist and songwriter. He was member of A.S.P.M., Blues Session and Marsyas. He died in September 1995. In 2006 he was inducted into the Beatová síň slávy (Beat Hall of Fame).
Till Eulenspiegel's Merry Pranks (German: "Till Eulenspiegels lustige Streiche") is a very well-known piece of music for orchestra by Richard Strauss. It is a tone poem (a piece of music which tells some kind of story). In this work, Richard Strauss describes the adventures of Till Eulenspiegel who was the character in a series of stories written in Germany many years ago. Till Eulenspiegel was a kind of folk hero. He was a naughty boy who got up to all kinds of tricks. The music is very humorous and describes his adventures.
The music is played by a large orchestra. There is a small clarinet (normally an E flat clarinet, although in Strauss's day he used a D clarinet) that describes the character of Till. Till is also represented by a French horn.
The music starts with the main theme, which is like saying: 'Once upon a time'. The horn plays one of Till's themes and this is taken up by the orchestra. The small clarinet is then heard, sounding like Till laughing. He rides his horse through the market and knocks lots of things off the stalls, then flirts with the girls (the first violin plays a theme which suggests love).
Till gets on his horse again. Then suddenly there is a funeral march. Till has been caught and he is sentenced to death. Till pleads to be let free and tries to joke his way out of his troubles, but the executioner takes no notice. Till is taken to the gallows (small clarinet), the flutes rattle as he reaches the top. The small clarinet describes his death scream, and then he is executed (strings playing pizzicato. There is a short silence, then the music returns to the opening 'Once upon a Time' theme, but the music finishes with a little joke, as if saying that someone like Till can never be destroyed.
Beatová síň slávy
Beatová síň slávy (Beat Hall of Fame or shortly BSS) is something like the Rock and Roll Hall of Fame. Czech Radio Beat honors the greatest legends of Czech rock music.
The extranet is a part of intranet that selected people outside the company can use.
Thomson's gazelle
The Thomson's gazelle ("Gazella thomsonii") is the most common gazelle in East Africa. It is a kind of small antelope. It is named after explorer Joseph Thomson and, as a result, is sometimes referred to as a "tommie". They can be found on ranches and farmland throughout East Africa, and survive long after other species have been killed off or migrated away.
Thomson's gazelles are commonly referred to as "tommies". Tommies stand at about half a meter (22-26 inches) tall and weigh in between 15 and 25 kilograms (35-55 pounds). Although very similar in appearance to the Grant's gazelle, they have some distinguishing features.
The tommy has adapted to drier life on the open grass plains of East Africa, mainly southern Kenya and northern Tanzania. Although tommies have many predators, including cheetahs, lions, leopards, crocodiles and hyenas, they are frequently the last animals left on an abandoned ranch or farmland.
Their major predators are cheetahs, which can run faster, but gazelles can outlast them in long chases and are able to make turns more speedily. This small antelope-gazelle can run extremely fast, from , to 96 km/h (60 mph) and zigzag, a peculiarity which often saves it from predators.
Sometimes they are also chased by leopards, lions and hyenas, but the gazelles are faster and more agile; these predators attack especially the young or infirm individuals. They can also be devoured by crocodiles and pythons, and their fawns are sometimes the prey of eagles, jackals, and baboons. A noticeable behaviour of Thomson's gazelles is their bounding leap, known as stotting or pronking, used to startle predators and display strength.
Mack Robinson (athlete)
Matthew MacKenzie Robinson (July 18, 1914 – March 12, 2000) was an American track athlete. He was the older brother of professional baseball player Jackie Robinson. Robinson was born in Cairo, Georgia. He moved to Pasadena, California when he was young and lived there most of his life. He ran track in high school and college. While at Pasadena City College, he set junior college records in several events. He won a silver medal at the 1936 Summer Olympics. He came in second to Jesse Owens in the 200m. Robinson later ran for the University of Oregon. While there, he won National Collegiate Athletic Association and Amateur Athletic Union titles. He is a member of the Oregon Sports Hall of Fame. Robinson spent his later years working for the city of Pasadena as a garbage collector and mailman. He tried to stop crime in the black neighborhoods of Pasadena. Robinson died in Pasadena in 2000. Several landmarks in Pasadena honor both Jackie and Mack Robinson, including the stadium at PCC.
Diene
In organic chemistry, a diene ( ) or diolefin ( ) is a hydrocarbon that contains two carbon pi bonds.
Conjugated dienes are functional groups, with a general formula of CH. Dienes and alkynes are functional isomers. Dienes occur occasionally in nature but are widely used in the polymer industry.
Dienes can be divided into three classes, depending on the relative location of the double bonds:
Compounds that contain more than two double bonds are called polyenes. Polyenes and dienes, share many of their properties.
An important reaction for conjugated dienes is the Diels–Alder reaction. Many specialized dienes have been developed to exploit this reactivity for the synthesis of natural products, e.g. Danishefsky’s diene.
Conjugated system
In chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons. Conjugated systems are created by several multiple bonds, each separated by single bonds. In general, conjugated systems may lower the overall energy of the molecule and increase how steady it is. They can contain lone pairs, radicals or carbonium ions. The compound may be cyclic, acyclic, linear or mixed. In most cases, the atoms in a molecule are held together by single bonds (where orbitals from adjacent atoms overlap). Molecules which have a conjugated system have unique properties different from normal compounds created by the sharing of the delocalized electrons among many atoms.
Conjugation is the overlap of one p-orbital with another across a sigma bond (or single bond) that is in between. (The d-orbitals of larger atoms can also contribute to a conjugated system).
A conjugated system has a region of overlapping p-orbitals, bridging the single bonds that are between. They allow a delocalization of pi electrons across all the adjacent aligned p-orbitals.
The pi electrons do not belong to a single bond or atom, but rather to a group of atoms.
The largest conjugated systems (with the greatest number of shared electrons) are in graphite, conductive polymers, and carbon nanotubes.
Different types of molecular structures can result in conjugation. For conjugation, all the neighboring atoms in a chain must have an available p-orbital. In many cases, conjugated systems are a series of a single bonds each followed by a double bond. Other systems exist. For example, furan (see picture) is a five-membered ring with two alternating double bonds and an oxygen in position 1. The Oxygen in furan has two lone pairs, one of which fills a p-orbital on that position. The lone pair electron makes conjugation possible on a five-membered ring. The presence of a nitrogen in the ring can be a source of pi orbitals needed for conjugation. Also, pi orbitals needed for conjugation can come from substituent groups α to the ring like: a carbonyl group (C=O), an imine group (C=N), a vinyl group (C=C), or an anion.
Conjugated systems are the main things that make up chromophores. Chromophores are light-absorbing parts of a molecule that can cause a compound to have a visible color. Chromophores are often present in various organic compounds and sometimes present in polymers that are colored or glow in the dark. Chromophores often consist of a series of conjugated bonds and/or ring systems, which can include C-C, C=C, C=O, or N=N bonds. Many times, chromophores have aromatic rings.
Prince Semien Fielder (born May 9, 1984 in Ontario, California) is an American Major League Baseball player. He currently plays for the Texas Rangers. He debuted in the MLB for the Milwaukee Brewers on June 13, 2005 when he was called up from the minor league Nashville Sounds. He was sent back down but was called up again on August 17, 2005 where he finished the season with the Brewers and was used as a pinch-hitter. Fielder is a 3-time All Star and is also one of 26 players in the 50 home run club.
Kurt Alder
Kurt Alder (July 10, 1902 – June 20, 1958) was a German chemist and Nobel laureate.
Alder was born in the industrial area of Königshütte, Silesia (modern day Chorzów, Upper Silesia, Poland). He received his early schooling there. Alder left the area for political reasons when Königshütte became part of Poland in 1922. He studied chemistry at the University of Berlin from 1922, and later at the University of Kiel where his earned a PhD in 1926 for work supervised by Diels.
In 1930 Alder was appointed reader for chemistry at Kiel, and promoted to lecturer in 1934. In 1936 he left Kiel to join I G Farben Industrie at Leverkusen, where he worked on synthetic rubber. In 1940, he was appointed Professor of Experimental Chemistry and Chemical Technology at the University of Cologne and Director of the Institute of Chemistry there. Throughout this time and despite the many obstacles to original research in Europe at the time, he continued a systematic program of investigations of his particular interests in the synthesis of organic compounds. In all he published more than 151 papers in this field.
Alder received several honorary degrees and other awards, most famously the 1950 Nobel Prize in Chemistry which he shared with his teacher Diels for their work on what is now known as the Diels–Alder reaction. The lunar crater Alder is named in his honour. The insecticide aldrin, created through a Diels–Alder reaction, is also named for him.
Kenichi Fukui
Kenichi Fukui (October 4, 1918–January 9, 1998) was a Japanese chemist. He won the 1981 Nobel Prize in Chemistry.
Fukui was the oldest of three sons of Ryokichi Fukui, who was a merchant. He was born in Nara, Japan.
He graduated from Kyoto Imperial University in 1941.
Fukui worked at the Army Fuel Laboratory of Japan during World War II.{
In 1943, he was appointed a lecturer in fuel chemistry at Kyoto Imperial University.
He was professor of physical chemistry at Kyoto University from 1951 to 1982.
He was president of the Kyoto Institute of Technology between 1982 and 1988.
Fukui shared the 1981 Nobel Prize with Roald Hoffmann. Fukui and Hoffmann worked separately on the mechanisms of chemical reactions. Fukui explained in his Nobel lecture that,
Woodward's rules
Woodward's rules are a set of rules about how organic chemical compounds absorb ultraviolet light.
They give information about the wavelength of the absorption maximum (symbol λ ) in an ultraviolet-visible (UV) spectrum of a compound. The rules are named after Robert Burns Woodward. He was a Harvard University professor who won the 1965 Nobel Prize in chemistry. The rules are sometimes called the Woodward-Fieser rules, to also honor Louis Fieser.
The rules build the prediction on the type of chromophores present, the substituents on the chromophores, and changes due to the solvent. Examples are conjugated carbonyl compounds, conjugated dienes, and polyenes.
One set of Woodward-Fieser rules for dienes is shown in table one. A diene is either homoannular with both double bonds contained in one ring or heteroannular with two double bonds distributed between two rings.
These rules predict the UV absorption maximum of compounds. Here are two examples:
In the compound on the left the base value is 214 nm (a heteroannular diene). This diene group has 4 alkyl substituents (labeled 1,2,3,4) and the double bond in one ring is exocyclic to the other (adding 5 nm for an exocyclic double bond). In the compound on the right, the diene is homoannular with 4 alkyl substituents. Both double bonds in the central B ring are exocyclic with respect to rings A and C.
Lemon shark
The Lemon shark is a shark that gets its name from its deep yellow back. Its belly is off-white. Lemon sharks are usually eight to ten feet long. They have long, sharp teeth for catching slippery fish. Lemon sharks are common on the southeast coast of the United States of America.
The Lemon shark gets its name from the fact that it is yellow in colour. The underside is usually white or a lighter yellowish colour. Besides yellow, the Lemon shark is also brown and olive grey in colour. The Lemon shark is stocky, blunt-nosed, and has two dorsal fins of similar size and shape. The first dorsal fin is low and positioned at the back of the pectoral fins, and the second dorsal is of similar shape and size and positioned at the front of the anal fin. The pelvic fin weakly concave (curving inwards) rear margins, and the pectoral fin's outer margin is slightly convex (curving outwards), and both fins are weakly falcate. The snout is round and shorter than the width of the mouth. There is no mid-dorsal ridge present on this species.
The upper teeth are narrow and broad with triangular smooth-edged cusps and finely serrated bases. These teeth get more oblique as they get closer to the corner of the mouth. The lower teeth are narrow and triangular with smooth-edged cusps.
Lemon shark scales are large and overlapping with 3 to 5 ridges. The middle ridge is high, sharp and separated by deep furrows, and the back margins are opposite the primary ridges. The basal plates and pedicels are broad.
Lemon sharks usually range between the lengths of , and have a growth rate of 0.21 inches per year (0.54 cm per year). The maximum length that can be reached by this species is between . Pups are between 24-26 inches (60-65 cm) at birth.
The Lemon shark is viviparous, meaning that they give live birth. After a gestation period of 10 to 12 months, pregnant females enter shallow nursery areas in spring and summer to give birth to litters of 4 to 17 pups. The pups have a very slow growth rate and remain within nursery grounds for quite a long time, where they are in less danger from predators. The mangroves that the young mainly inhabit are highly productive waters, creating an excellent area for feeding, but also an area of very low oxygen content. However, the Lemon shark has many adaptations that increase oxygen uptake, such as blood with an unusually high affinity for oxygen. As they grow, their range increases dramatically, from up to around . Maturity is reached at about 6 and a half years of age, and it is believed that the Lemon shark lives for up to 27 years.
When it comes to hunting, the Lemon shark is known to be very patient. They are able to use their yellow coloring to help them successfully hide in their natural habitat. They are often found swimming along the sand of the bottom of the water so they blend in easily. This makes it easy to hide from predators and also to be able to find prey.
It is believed that this shark has a special set up with the retina. This enables them to be able to see very clearly even in the murky depths under the water. The Lemon Shark can be aggressive to humans, and is known to have a powerful bite. Most of the attacks that have been noted were provoked, but not all. Since Lemon sharks can blend into their surroundings so well, it is easy for someone to accidentally disrupt the shark.
What is encouraging about the Lemon Shark is that they are able to do fairly well in captivity. That is not usually the case with species of sharks. Still, many experts worry that they won’t copy all they do in the wild in captivity so they don’t usually rely on such details and observations as facts if they can’t also be confirmed in the wild. They are very social, and they develop a hierarchy based on gender and size that is very complex.
The Lemon Shark is gentle in nature and doesn’t seem to be aggressive towards people, including divers. They have been known to bite humans but it is believed this is due to being provoked. They aren’t seen as a major threat to sharing the waters with humans.
The Lemon shark's diet consists mainly of bony fish and crustaceans. Catfish, mullet, jacks, croakers, porcupine fish, cowfish, guitarfish, stingrays, eagle rays, crabs and crayfish make up most of the Lemon shark's diet. Also, this species will eat sea birds and smaller sharks. Lemon sharks will eat until full with the rate of digestion dependent on the amount of food consumed at a single time.
The Lemon shark lives in the tropical and subtropical waters of the coastal areas of the Atlantic and Pacific Oceans. They stay in moderately shallow water, normally going no deeper than 80 meters (roughly 260 feet). They are often found in shallow waters near coasts and islands, by coral reefs, mangroves, bays, and sometimes even river mouths.
These sharks represent a small threat to humans. According to the International Shark Attack File, there have been only 10 unprovoked attacks by Lemon sharks, all occurring in Florida and the Caribbean. There have been no fatal attacks from this species. The Lemon shark does inhabit coastal waters which swimmers, surfers and divers commonly swim in. The low number of attacks by this species shows that it is a small threat to humans.
The Lemon shark is targeted by commercial and recreational fishermen along the U.S, Atlantic Ocean, Caribbean, and in the eastern Pacific Ocean. The US bottom longline fishery commonly targets this species and it is also caught as by-catch in both pelagic and gillnet fisheries. Their fins are highly prized and are exported to Asia for shark fin soup. Their skin may be used for leather and their meat is eaten by humans. There is some concern that populations in the western north Atlantic and eastern Pacific Ocean are in danger due to over-fishing.
Spined pygmy shark
The spined pygmy shark ("Squaliolus laticaudus") is one of the smallest sharks in the world. It is only seven to eight inches long on average. Spined pygmy sharks are dark gray or black on top. Their bellies glow in the dark. These sharks live very deep in the water (down to 6,500 feet) but they migrate up to about 650 feet at night, to hunt.
Spined pygmy sharks are harmless to humans.
Nurse shark
The nurse shark ("Ginglymostoma cirratum") is a bottom-dwelling shark, and is the only known species in the genus Ginglymostoma. They range in length from , and weigh .
Nurse sharks feed on crustaceans, mollusks, sea snakes, fish, coral, and tunicates.
The Nurse shark is common in the coastal tropical and subtropical waters of the eastern Pacific and the Atlantic Ocean.
Nurse sharks are nocturnal, and are very sluggish and are harmless unless bothered.
Nurse sharks have two spineless, rounded dorsal fins, with the first dorsal fin being much larger than the second, and they have one anal fin. The first dorsal fin is located over the pelvic fins. The caudal fin is more than one quarter of the total shark's length. The sub-terminal mouth is placed well in front of the eyes, the spiracles are small, and there are long barbels on the mouth. The Nurse shark has nasoral grooves, but there is no perinasal groove.
Adult Nurse sharks are usually light yellow to dark brown in colour. The young that are up to 60 cm (24 inches) long have small black spots, with an area of lightness surrounding each spot, covering the entire body. Larger young which are 70-120 cm long (28-47 inches) are capable of limited colour changes. Studies show that Nurse sharks kept out of sunlight become slightly lighter in colour, as compared to Nurse sharks which are exposed to sunlight. Nurse sharks with unusally colours (such as brilliant yellow or milky white) have been reported several times.
Nurse sharks have the simplest type of tooth arrangement found in sharks. This means that there is no overlapping between the teeth, and that forward movements of teeth leading to shedding does not depend on other teeth. With sharks that have many overlapping teeth, the replacement of teeth cannot take place until the outer blocking teeth are lost. Young Nurse sharks can replace their teeth quicker than adults. Also, teeth replacing occurs faster in summer, when water temperatures are higher. Averaging 2.2-2.7 metres (7.2-9 feet) in total length, and weighing 75-105 kg (165-232 pounds), adult females reach a larger size than adult males which are around 2.1-2.6 metres (7-8.5 feet) long, and weigh around 90-120 kg (198-265 pounds). Females reach maturity at about 2.3 metres (7.6 feet), and males reach maturity at about 2.1 metres (7 feet). New-born Nurse sharks range in length from 28 to 30 cm (11 to 12 inches), with growth rates of 13 cm (5 inches) and 2.3 kg (5 pounds) per year. Once the Nurse sharks reach maturity, their growth rates usually become much lower.
The Nurse shark is common in the coastal tropical and subtropical waters of the eastern Pacific and the Atlantic Ocean. In the Atlantic, it ranges from Senegal to Gabon, Rhode Island to southern Brazil, and Mexico to Peru. Also, some Nurse sharks have been reported in the Gulf of Gascogne, in southwest France. This species is common in shallow waters throughout the West Indies, south Florida and the Florida Keys.
The Nurse shark is a nocturnal animal that rests on sandy bottoms or in caves or crevices in shallow waters during the day. They are usually found in groups of up to 40, as they lie very close together, sometimes even piling on one another.
Nurse sharks are very active during the night. In addition to swimming near the bottom, the Nurse shark can move around on the sea floor, using its flexible, muscular pectoral fins as limbs. Large juveniles and adults are usually found around deep coral reefs, and rocky areas at depths of up to 3-75 metres (10-246 feet) during the daytime, and then they migrate into shallower waters of less than 20 metres (66 feet) deep after darkness.
Young Nurse sharks up to 1.7 metres (6 feet) are usually found around shallow coral reefs, grass flats or mangrove islands in waters which are 1-4 metres (3-13 feet) deep. They often lie in groups within limestone holes or under rock ledges.
Nurse sharks have been known to repeatedly return to the same caves and crevices in which they have rested before.
Nurse sharks are sluggish, and are not aggressive towards humans and will not attack unless they are provoked. If they are provoked, then they usually bite, but their bites are not deadly.
The Nurse shark is a nocturnal predator, and hunts alone. They feed on fish (such as catfish, mullets, and pufferfish) stingrays, mollusks (such as octopuses, squids, and clams), sea snakes, and tunicates. They move very slowly as they hunt along the bottom. They also consume algae, coral, crustaceans (such as lobsters, shrimps, and crabs), sea urchins, snails and bivalves.
The Nurse shark is one of the few species of sharks that can remain motionless in the water when it wants to. This not only helps it to conserve energy, it gives the Nurse shark an advantage when it comes to hunting. As it stays motionless, it's prey usually donesn't notice it, giving the Nurse shark a chance to ambush it's prey.
The mating season occurs once every 18 months, and lasts from the end of June till the end of July. They are ovoviviparous, with the gestation period lasting 6 months. Females can give birth to 21-29 pups at a time. However, sometimes the larger pups will feed on the smaller pups. As a result, only a small number of pups from each litter will live to the age of maturity. The young are born with spots, which fade as the sharks grow older. The average lifespan in the wild for these sharks is from 25 to 30 years.
Although the Nurse shark has no real predator, remains of Nurse sharks have been found in the stomachs of Tiger sharks, and Lemon sharks. Also, there have been reports of Bull sharks, and Great white sharks feeding on Nurse sharks.
Spiny dogfish
The spiny dogfish ("Squalus acanthias") is one of the most common and well known species of dogfish. It is a small species of shark, with an average length of 28-39 inches (70–100 cm), and reaching a maximum weight of 9.8 kg.
The dogfish is found in the Atlantic and Pacific Ocean, and can be found from the surface to depths as deep as 1,460 metres. The spiny dogfish feeds mainly on pelagic fish such as herring, menhaden, capelin, sand lance, and mackerel.
The spiny dogfish has a slim, long body and a flattened head. The snout is narrow, with a pointed tip. The eyes of this species are quite large. The first dorsal fin is located about halfway between the pectoral fins and the pelvic fins. The second dorsal fin is about two-thirds the size of the first one and is located behind the pelvic fins.
On the front of each dorsal fin there is a sharp spine attached to them, giving the spiny dogfish its name. The first spine is about half as long as the second spine. The pectoral fins form nearly perfect equilateral triangles, with rounded rear tips, and slightly concave rear margins. The pelvic fins are closer to the second dorsal fin than to the first dorsal fin. One the caudal fin, there is no notch on the upper lobe and the lower lobe is not well-developed. There is no anal fin on the Spiny dogfish.
The dorsal surface of the dogfish is slate-coloured and may have a brownish cast. There are rows of white spots along each side, from above the pectoral fins to above the pelvic fins. These spots are more visible on immature spiny dogfish, and they fade as the shark matures. With some individuals, the spots completely disappear. The edges of the dorsal fins and the caudal fin have a dusky-colour at birth, but this colour quickly fades. The ventral surface of the dogfish ranges from pale grey to pure white.
The average length of the spiny dogfish is 28-39 inches (70–100 cm), with adult males ranging from 24-35 inches (60–90 cm), and adult females ranging from 30-42 inches (76–107 cm). The maximum reported length of males is 39 inches (100 cm), and females is 49 inches (124 cm). Mature females can weigh as much as 3.2-4.5 kg (7-10 pounds), with a maximum recorded weight of 9.8 kg (22 pounds). The all-tackle game fish record is 7.14 kg (16 pounds), and was caught off the coast of Ireland in 1989.
In the western Atlantic, the spiny dogfish ranges from Greenland to Argentina, and in the eastern Atlantic it is found from Iceland and the Murmanski Coast (Russia) to South Africa, including the Mediterranean Sea and the Black Sea. In the western Pacific, the dogfish occurs from the Bering Sea to New Zealand, while in the eastern Pacific, this species is found from the Bering Sea to Chile.
Spiny dogfish are benthopelagic, meaning that they are found just above the bottom of the ocean. They are found from the surface to depths as deep as 1,460 metres. Spiny dogfish can be found in brackish water, but prefer seawater, and are commonly found in waters with the temperature of 7-15 °C. Spiny dogfish are found inshore and offshore, over continental and insular (island) shelve, and upper slopes. They are often found in enclosed bays and estuaries. They have been reported to enter freshwater but cannot survive there for more than a few hours.
Spiny dogfish have been found in the stomachs of cod, red hake, and goosefish, as well as other dogfish. Larger species of sharks, as well as seals and Killer whales also feed on the spiny dogfish. To defend itself, the dogfish curls into a ball, and strikes at predators with its spines on the dorsal fins.
The spiny dogfish usually feeds in groups. They feed mainly on pelagic fish such as herring, menhaden, capelin, sand lance, and mackerel, often consuming large numbers of them. They have been known to bite through fishing nets to be able to feed on the caught fish, usually releasing most of the fish. This has given the dogfish a bad reputation among fishermen. Other food items of this species includes molluscs (such as squid and octopus), crustacea (such as shrimp and crab), jellyfish, sea cucumber, algae, smaller sharks, and shark egg cases.
The gestation period of the spiny dogfish lasts up to 2 years. Spiny dogfish are ovoviviparous, meaning that the embryos develop inside eggs inside the female, and are nourished by yolk-filled sacs. Finally, the female gives birth to 1-20 pups, each one measuring around 20 to 33 centimeters. The spiny dogfish lives to the age of 20–75 years.
The dogfish poses little threat to humans, but if it is not handled properly, the spines on its dorsal fins can give a harmful wound. Also, the spiny dogfish has earned itself a bad reputation among fishermen due to its habit of biting through fishing nets to get at any fish which is caught in the nets.