the-french-artist/wikipedia_20220301.simple_sentence_split huggingface dataset:
Grignard reactions will not work if water is present; water causes the reagent to rapidly decompose.
So, most Grignard reactions occur in solvents such as anhydrous diethyl ether or tetrahydrofuran (THF), because the oxygen in these solvents stabilizes the magnesium reagent.
The reagent may also react with oxygen present in the atmosphere.
This will insert an oxygen atom between the carbon base and the magnesium halide group.
Usually, this side-reaction may be limited by the volatile solvent vapors displacing air above the reaction mixture.
However, chemists may perform the reactions in nitrogen or argon atmospheres.
In small scale reactions, the solvent vapors do not have enough space to protect the magnesium from oxygen.
Making a Grignard reagent
Grignard reagents are formed by the action of an alkyl or aryl halide on magnesium metal.
The reaction is conducted by adding the organic halide to a suspension of magnesium in an ether, which provides ligands required to stabilize the organomagnesium compound.
Typical solvents are diethyl ether and tetrahydrofuran.
Oxygen and protic solvents such as water or alcohols are not compatible with Grignard reagents.
The reaction proceeds through single electron transfer.
R−X + Mg → R−X•− + Mg•+
R−X•− → R• + X−
X− + Mg•+ → XMg•
R• + XMg• → RMgX
Grignard reactions often start slowly.
First, there is an induction period during which reactive magnesium becomes exposed to the organic reagents.
After this induction period, the reactions can be highly exothermic.
Alkyl and aryl bromides and iodides are common substrates.
Chlorides are also used, but fluorides are generally unreactive, except with specially activated magnesium, such as Rieke magnesium.
2 RMgX    R2Mg  +  MgX2
Many methods have been developed to initiate Grignard reactions that are slow to start.
These methods weaken the layer of MgO that covers the magnesium.
They expose the magnesium to the organic halide to start the reaction that makes the Grignard reagent.
Mechanical methods include crushing of the Mg pieces in situ, rapid stirring, or using ultrasound (sonication) of the suspension.
Iodine, methyl iodide, and 1,2-dibromoethane are commonly employed activating agents.
Chemists use 1,2-dibromoethane because its action can be monitored by the observation of bubbles of ethylene.
Also, the side-products are innocuous:
Mg  +  BrC2H4Br →  C2H4  +  MgBr2
Grignard reagents are produced in industry for use in place, or for sale.
As with at bench-scale, the main problem is that of initiation.
A portion of a previous batch of Grignard reagent is often used as the initiator.
Grignard reactions are exothermic; this exothermicity must be considered when a reaction is scaled-up from laboratory to production plant.
Reactions of Grignard reagents
Reactions with carbonyl compounds
Such reactions usually involve a water-based (aqueous) acidic workup, though this is rarely shown in reaction schemes.
In cases where the Grignard reagent is adding to a prochiral aldehyde or ketone, the Felkin-Anh model or Cram's Rule can usually predict which stereoisomer will form.
Reactions with other electrophiles
Another example is making salicylaldehyde (not shown above).
First, bromoethane reacts with Mg in ether.
Second, phenol in THF converts the phenol into Ar-OMgBr.
Third, benzene is added in the presence of paraformaldehyde powder and triethylamine.
Fourth, the mixture is distilled to remove the solvents.
Next, 10% HCl is added.
Salicylaldehyde will be the major product as long as everything is very dry and under inert conditions.
The reaction works also with iodoethane instead of bromoethane.
Formation of bonds to B, Si, P, Sn
Carbon–carbon coupling reactions
A Grignard reagent can also be involved in coupling reactions.
For example, nonylmagnesium bromide reacts with methyl p-chlorobenzoate to give p-nonylbenzoic acid, in the presence of Tris(acetylacetonato)iron(III), often symbolized as Fe(acac)3, after workup with NaOH to hydrolyze the ester, shown as follows.
Without the Fe(acac)3, the Grignard reagent would attack the ester group over the aryl halide.
For the coupling of aryl halides with aryl Grignards, nickel chloride in tetrahydrofuran (THF) is also a good catalyst.
Additionally, an effective catalyst for the couplings of alkyl halides is dilithium tetrachlorocuprate (Li2CuCl4), prepared by mixing lithium chloride (LiCl) and copper(II) chloride (CuCl2) in THF.
The Kumada-Corriu coupling gives access to [substituted] styrenes.
The oxidation of a Grignard reagent with oxygen takes place through a radical intermediate to a magnesium hydroperoxide.
Hydrolysis of this complex yields hydroperoxides and reduction with an additional equivalent of Grignard reagent gives an alcohol.
A reaction of Grignards with oxygen in presence of an alkene makes an ethylene extended alcohol.
These are useful in synthesizing larger compounds.
This modification requires aryl or vinyl Grignard reagents.
Adding just the Grignard and the alkene does not result in a reaction, showing that the presence of oxygen is essential.
The only drawback is the requirement of at least two equivalents of Grignard reagent in the reaction.
This can addressed by using a dual Grignard system with a cheap reducing Grignard reagent such as n-butylmagnesium bromide.
Nucleophilic aliphatic substitution
In the Boord olefin synthesis, the addition of magnesium to certain β-haloethers results in an elimination reaction to the alkene.
This reaction can limit the utility of Grignard reactions.
Grignard degradation
Grignard degradation at one time was a tool in structure identification (elucidation) in which a Grignard RMgBr formed from a heteroaryl bromide HetBr reacts with water to Het-H (bromine replaced by a hydrogen atom) and MgBrOH.
This hydrolysis method allows the determination of the number of halogen atoms in an organic compound.
In modern usage, Grignard degradation is used in the chemical analysis of certain triacylglycerols.
An example of the Grignard reaction is a key step in the industrial production of Tamoxifen. (
Tamoxifen is currently used for the treatment of estrogen receptor positive breast cancer in women.):
Wittig reaction
Fujimoto-Belleau reaction
Organolithium reagents
Sakurai reaction
Grignard knowledge: Alkyl coupling chemistry with inexpensive transition metals by Larry J. Westrum, Fine Chemistry  November/December 2002, pp.
10–13
Peach, the fruit or the tree
Princess Peach (or just "Peach"), a video game character
The Giant Magellan Telescope (GMT) will be the world's largest telescope when it is completed in 2025.
Instead of one large mirror, the GMT will have seven separate mirrors working together.
This will mean its collecting area is bigger than the actual mirror surfaces.
It will be made of seven  diameter mirror parts.
It will have a the resolving power of a  mirror.
Its collecting area will be the same as a  mirror.
The telescope will have over four times the ability to gather light than existing telescopes.
It will produce images up to ten times clearer than the Hubble Space Telescope.
It will cost $700 million.
Planned site
The location of the telescope is the Las Campanas Observatory, which is also the site of the Magellan Telescopes, some  northeast of La Serena, Chile.
This area has clear weather for most of the year.
The night sky in most of the surrounding Atacama Desert region is free from atmospheric pollution.
With few cities nearby this is probably one of the places least affected by light pollution.
All of this makes the area one of the best spots on Earth for long-term astronomical observation.
The telescope is unique because it will use seven mirror sections, each  in diameter.
These segments will then be arranged to form a single optical surface.
This is difficult as the surface of the outer six mirror segments is not radially symmetrical (that is, they are off-axis).
This requires a small change in the way mirrors are usually polished.
All seven mirrors will be arranged so that the reflecting surface of each of them is on a common axis.
One mirror will be in the center and the other six arranged symmetrically around the center.
A focal plane will be on-axis with the entire assembly.
The plan is to build seven identical off-axis mirrors.
The spare mirror has been made to replace a mirror when it needs recoating, a 1–2 week (per segment) process required every 1–2 years.
The Steward Observatory, at the University of Arizona, is making the mirrors in a laboratory beneath the university's football stadium.
It is using a rotating furnace to make the mirror.
The casting of the first mirror was completed on November 3, 2005.
But the time-consuming shaping and polishing will be completed in the autumn of 2011.
Member organizations
Observatories of the Carnegie Institution of Washington (OCIW)
Smithsonian Astrophysical Observatory
Astronomy Australia Limited
Korea Astronomy and Space Science Institute
Giant Magellan Telescope home page
Article from the MIT news office
New Scientist article on the telescope
COSMOS article on the telescope
Painted outline of the mirrors at the parking lot of the Observatories of the Carnegie Institution in Pasadena
Stinging nettles (Urtica dioica) are a type of plant which have stinging defensive hairs on the leaves and stems.
Stinging nettles can be found in America, Europe and Asia.
Sting mechanism
The hairs inject histamine and other chemicals that produce a stinging sensation when contacted by humans and other animals.
Soaking stinging nettles in water or cooking removes the stinging chemicals from the plant, which allows them to be handled and eaten without injury.
The plant has been used as medicine, food, tea and fibre.
Nettles are sometimes used in cheesemaking, as nettle soup or as substitute for spinach.
Its stems contain a bast fibre that is used for the same purposes as linen.
Nettles have been used to make clothing for 2,000 years.
Stinging nettles are important food plants for several butterflies, like the peacock butterfly and the small tortoiseshell.
Also some deers and other animals eat the plant, preferred the leaf shot.
The Ferrari F50 is a sports car made by Ferrari in 1995.
It was created to celebrate the company's 50th anniversary.
The car has two doors.
It is a two-seated convertible with a removable hardtop.
It has a 4.7 L V12 engine that was based on the 3.5 L V12 used in the 1992 Ferrari F92A Formula One car.
Only 349 Ferrari F50's were made.
This was because Ferrari wanted it to be rare.
The last F50 was produced in Maranello, Italy in July 1997.
A mass spectrum is an intensity versus m/z (mass-to-charge ratio) plot that represents a chemical analysis.
The mass spectrum of a sample is a pattern representing the distribution of ions by mass (more correctly: mass-to-charge ratio) in a sample.
It is a histogram usually made using an instrument called a mass spectrometer.
Not all mass spectra of a given substance are the same.
It can depend on the operating conditions of the instrument.
For example, some mass spectrometers break the analyte molecules into many pieces; others observe the intact molecular masses with little fragmentation.
A mass spectrum can represent many different types of information based on the type of mass spectrometer and the specific experiment; however, all plots of intensity vs. mass-to-charge are called "mass spectra".
In the past, chemists with PhD degrees were needed to interpret mass spectra.
Today, computer programs read the data and identify the compounds in a sample.
Interactive tutorial on mass spectra  National High Magnetic Field Laboratory
Weighing Atoms: A layperson's introduction to mass spectrometry  National High Magnetic Field Laboratory
What's in an Oil Drop: A layperson's introduction to Fourier Transform Ion Cyclotron Resonance   National High Magnetic Field Laboratory
Quantities, Units and Symbols in Physical Chemistry (IUPAC green book)
An introductory video on Mass Spectrometry The Royal Society of Chemistry
Stuntman is a racing/action video game that was published by Infogrames and Atari.
It was released for the PlayStation 2 and the Game Boy Advance systems.
The game is also featured as a mobile phone game which could be downloaded.
Stuntman was followed by the 2007 sequel, Stuntman: Ignition.
The game received positive reviews, GameSpot gave it a 8.0 out of 10 and IGN gave it a 8.6 out of 10.
The game was followed by sequel, called Stuntman: Ignition released in 2007.
Stuntman at MobyGames
"Eh, Eh (Nothing Else I Can Say)" is a single by Lady Gaga.
It appeared on Gaga's debut album The Fame and was released as a single on January 10, 2009.
Its music video references Gaga's Italian heritage.
Though the single did not chart in the United States, the Recording Industry Association of America certified the song gold on February 29, 2016, for shipments and streams equal to 500,000 copies there.
"Eh, Eh" charted in the top ten in France, New Zealand and Sweden.
{{DISPLAYTITLE:SN2 reaction}}
The SN2 reaction (also known as bimolecular nucleophilic substitution) is a substitution reaction in organic chemistry.
It is a type of nucleophilic substitution, where a lone pair from a nucleophile attacks an electron deficient electrophilic center and bonds to it.
This expels another group called a "leaving group".
So, the incoming group replaces the leaving group in one step.
Since two reacting species are involved in the slow, rate-determining step of the reaction, this leads to the name bimolecular nucleophilic substitution, or SN2.
Among inorganic chemists, the SN2 reaction is often known as the interchange mechanism.
The reaction most often occurs at an aliphatic sp3 carbon center with an electronegative, stable leaving group attached to it - 'X' - frequently a halide atom.
The breaking of the C-X bond and the formation of the new C-Nu bond occur simultaneously to form a transition state in which the carbon under nucleophilic attack is pentacoordinate, and approximately sp2 hybridized.
The nucleophile attacks the carbon at 180° to the leaving group, since this provides the best overlap between the nucleophile's lone pair and the C-X σ* antibonding orbital.
The leaving group is then pushed off the opposite side and the product is formed.
In an example of the SN2 reaction, the attack of OH− (the nucleophile) on a bromoethane (the electrophile) results in ethanol, with bromide ejected as the leaving group:
A SN2 reaction occurs if the backside route of attack is not blocked by other atoms in the molecule (sterically hindered by substituents on the substrate).
So, this mechanism usually occurs at an unhindered primary carbon center.
If there is steric crowding on the substrate near the leaving group, such as at a tertiary carbon center, the substitution will use an SN1 rather than an SN2 mechanism, (an SN1 would also be more likely with blocked molecules because a sufficiently stable carbocation intermediary could be formed.)
In coordination chemistry, associative substitution proceeds by a similar mechanism as SN2.
Factors affecting the rate of the reaction
Substrate.
The substrate plays the most important part in determining the rate of the reaction.
This is because the nucleophile attacks from the back of the substrate, thus breaking the carbon-leaving group bond and forming the carbon-nucleophile bond.
Therefore, to maximise the rate of the SN2 reaction, the back of the substrate must be as unhindered as possible.
Overall, this means that methyl and primary substrates react the fastest, followed by secondary substrates.
Tertiary substrates do not participate in SN2 reactions, because of steric hindrance.
Nucleophile.
The methoxide anion, for example, is both a strong base and nucleophile because it is a methyl nucleophile, and is thus very much unhindered.
Tert-butoxide, on the other hand, is a strong base, but a poor nucleophile, because of its three methyl groups hindering its approach to the carbon.
Nucleophile strength is also affected by charge and electronegativity: nucleophilicity increases with increasing negative charge and decreasing electronegativity.
For example, OH- is a better nucleophile than water, and I- is a better nucleophile than Br- (in polar protic solvents).
In a polar aprotic solvent, nucleophilicity increases up a column of the periodic table as there is no hydrogen bonding between the solvent and nucleophile.
In this case, nucleophilicity mirrors basicity.
I- would therefore be a weaker nucleophile than Br- because it is a weaker base.
The solvent affects the rate of reaction because solvents may or may not surround a nucleophile, thus hindering or not hindering its approach to the carbon atom.
Polar aprotic solvents, like tetrahydrofuran, are better solvents for this reaction than polar protic solvents because polar protic solvents will be solvated by the solvent hydrogen bonding to the nucleophile.
This hinders it from attacking the carbon with the leaving group.
Leaving group.
The leaving group affects the rate of reaction.
The more stable leaving group is, the more likely that it will take the two electrons of its carbon-leaving group bond with it when the nucleophile attacks the carbon.
Therefore, the weaker the leaving group is as a conjugate base, the better the leaving group.
Similarly,  the stronger its corresponding acid, the better the leaving group.
Examples of good leaving groups are the halides (except fluoride) and tosylate.
But HO- and H2N- are not good leaving groups.
Reaction kinetics
The rate of an SN2 reaction is second order, as the rate-determining step depends on the nucleophile concentration, [Nu−] as well as the concentration of substrate, [RX].
r = k[RX][Nu−]
This is a key difference between the SN1 and SN2 mechanisms.
In the SN1 reaction, the nucleophile attacks after the rate-limiting step is over.
But in a SN2 reaction, the nucleophile forces off the leaving group in the limiting step.
In other words, the rate of SN1 reactions depend only on the concentration of the substrate while the SN2 reaction rate depends on the concentration of both the substrate and nucleophile.
In cases where both mechanisms are possible (for example at a secondary carbon center), the mechanism depends on solvent, temperature, concentration of the nucleophile or on the leaving group.
SN2 reactions are generally favored in primary alkyl halides or secondary alkyl halides with an aprotic solvent.
They occur at a negligible rate in tertiary alkyl halides due to steric hindrance.
SN2 and SN1 are two extremes of a sliding scale of reactions.
It is possible to find many reactions which exhibit both SN2 and SN1 character in their mechanisms.
For instance, it is possible to get a contact ion pairs formed from an alkyl halide in which the ions are not fully separated.
When these undergo substitution the stereochemistry will be inverted (as in SN2) for many of the reacting molecules but a few may show retention of configuration.
SN2 reactions are more common than SN1 reactions.
E2 competition
A common side reaction taking place with SN2 reactions is E2 elimination: the incoming anion can act as a base rather than as a nucleophile, removing a proton and leading to formation of the alkene.
This effect can be demonstrated in the gas-phase reaction between a sulfonate and a simple alkyl bromide taking place inside a mass spectrometer:
With ethyl bromide, the reaction product is predominantly the substitution product.
As steric hindrance around the electrophilic center increases, as with isobutyl bromide, substitution is disfavored and elimination is the predominant reaction.
Other factors favoring elimination are the strength of the base.
With the less basic benzoate substrate, isopropyl bromide reacts with 55% substitution.
In general, gas phase reactions and solution phase reactions of this type follow the same trends, even though in the first, solvent effects are dropped.
Roundabout mechanism
A development attracting attention in 2008 concerns a SN2 roundabout mechanism observed in a gas-phase reaction between chloride ions and methyl iodide with a special technique called  crossed molecular beam imaging.
When the chloride ions have sufficient velocity, the energy of the resulting iodide ions after the collision is much lower than expected, and it is theorized that energy is lost as a result of a full roundabout of the methyl group around the iodine atom before the actual displacement takes place.
{{DISPLAYTITLE:SN1 reaction}}
The SN1 reaction is a substitution reaction in organic chemistry. "
SN" stands for nucleophilic substitution and the "1" represents the fact that the rate-determining step involves only one molecule (unimolecular).
The reaction involves a carbocation intermediate.
Some common SN1 reactions are of secondary or tertiary alkyl halides under strongly basic conditions or, under strongly acidic conditions, with secondary or tertiary alcohols.
With primary alkyl halides, the alternative SN2 reaction occurs.
Among inorganic chemists, the SN1 reaction is often known as the dissociative mechanism.
Christopher Ingold et al.
first proposed the reaction mechanism in 1940.
An example of a reaction taking place with an SN1 reaction mechanism is the hydrolysis of tert-butyl bromide with water to form tert-butyl alcohol:
This SN1 reaction takes place in three steps:
Formation of a tert-butyl carbocation by separation of a leaving group (a bromide anion) from the carbon atom; this step is slow and reversible.
Nucleophilic attack: the carbocation reacts with the nucleophile.
If the nucleophile is a neutral molecule (that is, a solvent) a third step is required to complete the reaction.
When the solvent is water, the intermediate is an oxonium ion.
This reaction step is fast.
Deprotonation: Removal of a proton on the protonated nucleophile by water acting as a base forming the alcohol and a hydronium ion.
Because the first step is the bottleneck or "rate-determining step" chemists classify the entire reaction mechanism as SN1.
Only one molecule is needed for that step.
Scope of the reaction
Sometimes a molecule can react using either an SN1 or an SN2 mechanism.
The SN1 mechanism will win this competition when the central carbon atom is surrounded by bulky groups because such groups sterically hinder the SN2 reaction.
Additionally, bulky substituents on the central carbon increase the rate of carbocation formation because of the relief of steric strain that occurs.
The resultant carbocation is also stabilized by both inductive stabilization and hyperconjugation from attached alkyl groups.
The Hammond-Leffler postulate says that this too will increase the rate of carbocation formation.
The SN1 mechanism therefore dominates in reactions at tertiary alkyl centers and is further observed at secondary alkyl centers in the presence of weak nucleophiles.
An example of a reaction proceeding in a SN1 way is the synthesis of 2,5-dichloro-2,5-dimethylhexane from the corresponding diol with concentrated hydrochloric acid:
As the alpha and beta substitutions increase with respect to leaving groups, the reaction is diverted from SN2 to SN1.
The carbocation intermediate formed in the reaction's rate limiting step is an sp2 hybridized carbon with trigonal planar molecular geometry.
This allows two different paths for the nucleophilic attack, one on either side of the planar molecule.
If neither path is preferentially favored, these two paths will be used equally, yielding a racemic mix of enantiomers if the reaction takes place at a stereocenter.
This is illustrated below in the SN1 reaction of S-3-chloro-3-methylhexane with an iodide ion, which yields a racemic mixture of 3-iodo-3-methylhexane:
However, an excess of one stereoisomer can be observed, as the leaving group can remain close to the carbocation intermediate for a short time and block nucleophilic attack.
This is very different than the SN2 mechanism, which does not mix the stereochemistry of the product (a stereospecific mechanism).
The SN2 mechanism always inverts the molecule's stereochemistry.
Side reactions
Two common side reactions are elimination reactions and carbocation rearrangement.
If the reaction is performed under warm or hot conditions (which favor an increase in entropy), E1 elimination is likely to predominate, leading to formation of an alkene.
At lower temperatures,  SN1 and E1 reactions are competitive reactions.
So, it becomes  difficult to favor one over the other.
Even if the reaction is performed cold, some alkene may be formed.
If an attempt is made to perform an SN1 reaction using a strongly basic nucleophile such as hydroxide or methoxide ion, the alkene will again be formed, this time via an E2 elimination.
This will be especially true if the reaction is heated.
Finally, if the carbocation intermediate can rearrange to a more stable carbocation, it will give a product derived from the more stable carbocation rather than the simple substitution product.
Solvents will change the reaction rate.
Since the SN1 reaction involves formation of an unstable carbocation intermediate in the rate-determining step, anything that can help this will speed up the reaction.
The normal solvents of choice are both polar (to stabilize ionic intermediates in general) and protic (to solvate the leaving group in particular).
Typical polar protic solvents include water and alcohols, which will also act as nucleophiles.
The Y scale correlates solvolysis reaction rates of any solvent (k) with that of a standard solvent (80% v/v ethanol/water) (k0) through
with m a reactant constant (m = 1 for tert-butyl chloride),
Y a solvent parameter, and
k0 is the reaction rate using a solvent of 80% ethanol (measured by volume).
Electrophilic Bimolecular Substitution as an Alternative to Nucleophilic Monomolecular Substitution in Inorganic and Organic Chemistry / N.S.Imyanitov.
J. Gen. Chem.
USSR (Engl.
Transl.)
1990; 60 (3); 417-419.
Unimolecular Nucleophilic Substitution does not Exist! /
N.S.Imyanitov.
SciTecLibrary
Diagrams: Frostburg State University
Exercise : the University of Maine
Study Organic Chemistry, Resources for Success in Organic Chemistry
SC Austria Lustenau is a football club from Lustenau, Vorarlberg.
The club is playing in the Erste Liga, the second division in Austria.
The club was founded in June 1914 as football department of Turnerbund Lustenau and was named FA Turnerbund Lustenau.
This name had the club till 1936.
For not having a football assosiation in Vorarlberg the club only played friendly matches.
During the time of  First World War there were no matches.
In 1920 the club started in a regular championship.
The first success was the Vorarlberg championship in the 1929/30 season.
They were qualified for the Austrian Amateur Championship and reached the final versus Kremser SC.
In 1936 the club left the Turnerbund Lustenau and became a club of its own.
The were renamed to SC Austria Lustenau.
In the following years they reached several titels.
In 1994 they won the Regionalliga West and were promoted to the First League, the second division in Austrian football.
From 1997 to 2000 they played in the Bundesliga, the top division of Austrias football.
Since the relegation 2 000 they played in the 2.
The biggest success so far was the Cup final in 2010/11.
Austria Lustenau was the first club from Vorarlberg which ever reached a Cup final.
The match was lost against SV Ried.
In 2020 they reached again the Cup final but lost again versus FC Red Bull Salzburg.
Updated 17 December 2021.
Runner-up Austrian Amateur Championship: 1930 (FA Turnerbund)
Champion 2nd division: 1997
Champion Regionalliga West(3rd division): 1994
Champion Tyrol/Vorarlberg: 1977
Vorarlberger Champion: 1930 (FA Turnerbund), 1937, 1946, 1949, 1965, 1977, 1978, 1980 (Austria) , 2005 (Austria-Amateure)
Vorarlberger Cup : 1936, 1949, 1951, 1958, 1980 (Austria) 1999 (Austria-Amateure)
Stuntman: Ignition is a racing/action video game that was published by THQ and was developed by Paradigm Entertainment.
It was released for the PlayStation 2, PlayStation 3 and the Xbox 360 systems.
Stuntman: Ignition was the sequel to the 2002 video game, Stuntman.
The game received positive reviews, GameSpot gave it a 7.5 out of 10 and IGN gave it a 7.1 out of 10.
Stuntman: Ignition at GameSpot
is a Japanese game designer, professional racing driver, and CEO of Polyphony Digital and producer of the Gran Turismo series.
The Cradle of Humankind is a World Heritage Site.
It was first named by UNESCO in 1999.
The site is about 50 kilometres northwest of Johannesburg, South Africa in the Gauteng province, and occupies .
The site's limestone caves, including the Sterkfontein Caves, were where fossils were found.
A 2.3-million year-old fossil Australopithecus africanus (nicknamed 'Mrs. Ples') was found in 1947 by Robert Broom and John T. Robinson.
The find followed the 1924 discovery of the juvenile Australopithecus africanus skull, 'Taung Child', by Raymond Dart, at Taung in the North West Province of South Africa, where excavations still continue.
The name Cradle of Humankind reflects the fact that the site has produced a large number, as well as some of the oldest, hominid fossils ever found, some dating back as far as 3.5 million years ago.
Sterkfontein alone has produced more than a third of early hominid fossils ever found.
The remains of several partial skeletons of a previously unknown  Australopithecan species were found in 2008 near Johannesburg.
They have been dated to about two million year ago (mya).
A recent re-examination of two partial skeletons of Australopithecus sediba has led to its identification as close to the origin of the genus Homo.
Not all palaeoanthropologists agree this is a new species.
A new analysis shows this species had a human-like pelvis, hands and teeth, and a chimpanzee-like foot.
In six separate research reports, palaeontologists reported on the anatomy of a juvenile male skeleton, MH1, a female skeleton, known as MH2, and an isolated adult tibia or shinbone, known as MH4.
The findings suggest that some species of australopithecine climbed trees, some walked on the ground, and some did both.
"Its small heel resembles that of a chimpanzee more than it does a human.
This suggests it likely walked with an inward rotation of the knee and hip, with its feet slightly twisted.
This primitive way of walking might have been a compromise between upright walking and tree climbing, the researchers suggest, since A. sediba seems to have had more adaptations for tree-climbing than other australopithecines".
Colleagues in England  investigated the teeth.
Like other parts of the skeleton, the teeth are a mosaic of primitive and human-like features.
2011 plane crash
The Lokomotiv Yaroslavl plane crash occurred on Wednesday, September 7, 2011 at 16:02 local time, when a Yak-Service Yakolev Yak-42 airplane, with the professional ice hockey team and coaching staff of Lokomotiv Yaroslavl of the Kontinental Hockey League, crashed near Yaroslavl, Russia.
The team was going to Minsk, Belarus, to start the 2011-12 KHL season against Dinamo Minsk.
44 out of the 45 people on board were confirmed dead, one crew member survived.
Statistics in KHL
Note: GP = Games played, W = Wins, L = Losses, OTL = Overtime/Shootout Losses, Pts = Points, GF = Goals for, GA = Goals against
Lokomotiv Yaroslavl official website
Home arena, Statistics, History
The overhand knot is the simplest knot that can be created.
It is often used as a stopper knot at the end of a rope.
Knot theory is the study of knots in mathematics.
In knot theory, the ends of the rope are attached so that there is no possible way for the knot to be untied.
Peter Guthrie Tait was the first person to make charts describing mathematical knots in the 1860s.
Richard H. Crowell and Ralph Fox, Introduction to Knot Theory,  1977,
Gerhard Burde and Heiner Zieschang, Knots, De Gruyter Studies in Mathematics, 1985, Walter de Gruyter,
Louis H. Kauffman, On Knots, 1987,
The most famous are those made for the Russian Tsars Alexander III and Nicholas II.
They were Easter gifts for their wives and mothers, and are called the 'Imperial' Fabergé eggs.
The House of Fabergé made about 52 imperial eggs, of which 46 have survived.
Two more were planned for Easter 1918, but were not delivered, due to the Russian Revolution.
List of Fabergé Tsar Imperial Easter eggs
List of the Kelch eggs
Faberge also made eggs for Alexander Kelch, a Siberian gold mine industrialist, as gifts for his wife Barbara (Varvara) Kelch-Bazanova.
Other Fabergé eggs
Anthology was a greatest hits album by Selena.
The album included remixed songs from Selena's early music career.
Two EPs were released as a promotion.
The album sold over 1,200,000 copies.
I'm Getting Used To You (club remix)
Yo Fui Aquella
Disco Medley (Full; Club Remix)
Ramalazo
Pa'Que Me Sirve La Vida
Differentes
Rama Caida
Yo Te Dare
La Puerta Se Cerro
Corazoncito
Carino Mio
Salta La Ranita
Te Amo Solo A Ti
Two EPs were released.
Both of them contained five songs each.
All My Hits/Todos Mis Exitos was a greatest hits album by Selena.
The album included a collectable rose-pin for fans.
The album sold over 1,200,000 copies in the United States.
Track lisiting
All My Hits/Todos Mis Exitos Vol.
2 was the second series of the All My Hits collection.
It was a greatest hits album by Selena.
The album included a heart-necklace for fans.
The album sold over 400,000 copies in the United States.
Enamorada de Ti (Club Remix)
Techno Cumbia (Radio Edit Version)
A Million to One (Medley)
Si Una Ves
No Me Queda Mas (Astro 95 live)
Muñequito De Trapo
Tu Robaste Mi Corazón (with Pete Astudillo)
Bidi Bidi Bom Bom (Astro 95 Live)
Aunque No Salga El Sol (New Version)
Yo Fui Aquella (New Version)
Cien Años (Mirachi Version)
Note that RIAA has launched its Oro y De Platino certification scheme for those albums the 50% of the content of which are in Spanish, initially, the award-levels for Oro y De Platino were: Gold=100,000 and Platinum=200,000.'
Ones is a greatest hits album by Selena.
The album included an unreleased ballad song.
The album sold over 500,000 copies in the United States.
Disc 2 Music video DVD
Buenos Amigos (Duet With Álvaro Torres)
Dónde Quiera Que Estés (Duet With Barrio Boyzz)
The JKLF claims that they are not Islamist, but are nationalist, and opposes  the emergence of the territories into either Pakistan or India but rather wants the region of Kashmir to separate from the three countries and become independent.
Mirador de la Flor () is a life-sized statue that is in Corpus Christi, Texas.
The statue is a memorial to American singer Selena.
The statue was ordered by the Mayor of Corpus Christi as a tourist attraction in 1997.
Hundreds of fans visit the statue weekly from all over the world.
The statue faces Corpus Christi bay, where the gun that killed Selena was thrown.
A second life-sized statue of Selena was made in Mexico in March 2011.
Marie Joséphine of Savoy (Maria Giuseppina Luigia; 2 September 1753 – 13 November 1810) was the wife of the future Louis XVIII of France.
She was a princess of Savoy by birth, became the titular Queen consort, and was known by her title: Her Royal Highness, Countess of Provence (comtesse de Provence).
She was born at the Royal Palace of Turin on 2 September 1753 and was the third child and second daughter of Victor Amadeus and his wife the Spanish Infanta Maria Antonia of Spain.
At the time of her birth her grandfather, Charles Emmanuel III of Sardinia, was the King of Sardinia.
Maria Giuseppina was engaged to the French Prince Louis Stanislas of France.
He was known as the Count of Provence.
They were married on 16 April 1771 by proxy in the Turin.
They were married in person on 14 May 1771 at the Palace of Versailles.
A luxurious ball followed the wedding on 20 May.
She was considered to be ugly.
Louis Stanislas hated his wife.
We know today that these rumors were created by those who supported Marie Antoinette as a rivalry soon emerged after the youngest brother 'comte d'Artois', married the Comtesse's sister, thereby bringing yet another Savoyard princess to Versailles and creating an Italian party at court.
In France she was known as Marie Joséphine de Savoie.
She had a high rank at court as her husband was a grandson of the reiging king.
She was a cousin of the ill-fated Princess of Lamballe who was instrumental in the arrangement of the marriage.
At the death of her husband’s grandfather Louis XV in 1774, her brother-in-law succeeded as Louis XVI.
She became pregnant in 1774 and 1781, but both pregnancies ended in miscarriage.
In 1791 Marie Joséphine went to Germany.
During the period of exile, the Count and Countess fought constantly.
Some historians have suggested Marie Joséphine's possible lesbian relationship with a lady-in-waiting as the primary cause for discord between the couple.
Marie Joséphine died of an edema at Hartwell House, English residence of the exiled French royal family.
Marie Joséphine was laid to rest in the Lady Chapel of Westminster Abbey.
Her body was removed a year later on Louis's orders and buried in the Kingdom of Sardinia; today in Cagliari Cathedral.
Jerusalem is Islam's third holiest city after Mecca and Medina in Saudi Arabia.
The Haram al Sharif (Temple Mount) of Jerusalem is believed by Muslims to be the location from which Muhammad ascended to Jannah (paradise); there is no mention of Jerusalem in the Koran, however.
This widely accepted Islamic belief raises the religious and spiritual importance to them of the Dome of the Rock and the adjacent al-Aqsa Mosque.
Muslims are sensitive to and mindful of the circumstance that two mosques along with the rest of East Jerusalem are claimed and illegally occupied by the state of Israel.
Specific impulse (often shortened to Isp) is a way to describe how well a rocket performs.
It is also used to describe how well a jet engine performs.
It can be used to compare rockets of different sizes.
It is a way to know how much force a given engine makes for each bit of fuel.
To do this, one needs to know how much fuel is in the engine.
A high specific impulse means that a rocket needs less fuel to perform as well.
If the specific impulse is lower, it means that the rocket needs more fuel to perform as well.
Specific impulse is a useful value to compare rocket or jet engines.
It is used much like miles per gallon or litres per 100 kilometres is used to compare cars.
An engine with a higher specific impulse uses fuel better.
This means that the same amount of fuel lets the rocket go faster after all fuel is depleted.
A rocket engine with a higher specific impulse doesn't mean it's 'more powerful'.
That is, it will not make the rocket accelerate harder.
In fact, the designs for engines with the highest specific impulse, like ion engines, are the 'weakest' of all types of engines.
They accelerate the rocket slowly but steadily over a long period of time using only a tiny amount of fuel.
In a race between two rockets with the same amount of fuel and two different engines the one with the more powerful engine will take an early lead, but when it burns down all its fuel, the rocket with higher specific impulse will still have some fuel left and will continue to accelerate.
Eventually it will overtake its counterpart and will win the race if the distance is big enough for it to use its long-term advantage.
There are two ways people find the number for specific impulse.
To find the specific impulse, one divides the impulse by the amount of fuel.
Impulse is a measurement of how much force a rocket motor makes and for how long.
A motor that makes a low force for a long time can sometimes have a higher impulse than a motor that makes a high force for a short time.
Impulse is measured in Newtons times seconds (N*s).
The amount of fuel used to find specific impulse can be measured in different ways.
It is sometimes measured in mass and sometimes in weight.
When the amount of fuel is measured in mass, the specific impulse is expressed as a speed.
This is usually in meters per second.
When specific impulse is measured as a speed, it has another name.
It is also called the effective exhaust velocity.
The other way to measure the amount of fuel is weight.
If weight is used, the specific impulse is in units of time, usually in seconds.
These two ways are both common.
They both compare the performance of engines.
When the specific impulse is higher, less fuel is needed to make the rocket perform at a certain level.
So, a fuel is more efficient if the specific impulse is higher.
Be careful not to confuse thrust and specific impulse.
Thrust is only the force made by a rocket at one point in time.
Specific impulse is a measure of the force based on how much fuel there is.
When people find specific impulse, the only fuel counted is in the rocket before it gets fired.
This includes the fuel and the oxidizer (the part of the fuel that helps the fuel burn).
The oxidizer is sometimes oxygen, or often something else (see Rocket engine#Liquids, solids and hybrids).
Jet (airplane) engines use fuel better than rocket engines.
This is because the gases do not escape as fast.
Because they do not escape as fast, the exhaust does not carry away as much energy.
This means that the jet engine uses a lot less energy to push the jet.
It is also because the air that goes through the engine as the jet flies through the air helps the fuel to burn faster.
Model rocketry
Specific impulse is also used to describe how well model rocket motors work.
In the table below are some of Estes' claimed values for specific impulses for several of their rocket motors: Estes Industries is a large, well known American seller of model rockets and rocket parts.
The specific impulse for model rocket motors is much lower than for many other rocket motors because the black powder is used as a fuel.
Black powder is used in model rocket motors because it costs less.
Larger Rocket Engines
The most common way to measure specific impulse today uses seconds.
This is used both in the SI (metric system) world as well as where English units are used.
This way the units are identical everywhere.
This means specific impulse can be used to compare engine performance in any country.
Most companies that make rocket motors or jet engines use seconds to advertise their product’s performance.
The other common way to measure specific impulse is in meters per second (m/s), which is also called effective exhaust velocity.
For many engines the effective exhaust velocity is different from the speed that the gases actually come out of the nozzle.
Impulse (physics) - the change in momentum
RPA - Design Tool for Liquid Rocket Engine Analysis
List of Specific Impulses of various rocket fuels
An aromatic hydrocarbon, or arene, is a hydrocarbon ring compound.
It has alternating double and single bonds between carbon atoms forming rings.
Many of the compounds have a sweet scent, hence the term 'aromatic'.
The ring of six carbon atoms in aromatic compounds is known as a benzene ring, after the simplest possible hydrocarbon ring, benzene.
Aromatic hydrocarbons can be monocyclic (MAH) or polycyclic (PAH).
Some non-benzene-based compounds called heteroarenes, which follow Hückel's rule, are also aromatic compounds.
In these compounds, at least one carbon atom is replaced by one of oxygen, nitrogen, or sulfur.
Benzene ring model
Benzene, C6H6, is the simplest aromatic hydrocarbon and was recognized as the first aromatic hydrocarbon, with the nature of its bonding first being recognized by Kekulé in the 19th century.
Each carbon atom in the hexagonal cycle has four electrons to share.
One goes to the hydrogen atom, and one each to the two neighboring carbons.
This leaves one to share with one of its two neighboring carbon atoms, which is why the benzene molecule is drawn with alternating single and double bonds around the hexagon.
The structure is also illustrated as a circle around the inside of the ring to show  six electrons floating around in delocalized molecular orbitals the size of the ring itself.
This also represents the equivalent nature of the six carbon-carbon bonds each equivalent to ~1.5.
The electrons are visualized as floating above and below the ring with the electromagnetic fields they generate acting to keep the ring flat.
Display aromaticity.
The carbon-hydrogen ratio is high.
They burn with a sooty yellow flame because of the high carbon-hydrogen ratio.
They undergo substitution reactions.
The circle symbol for aromaticity was introduced by Sir Robert Robinson and his student James Armit in 1925 and popularized starting in 1959 by the Morrison & Boyd textbook on organic chemistry.
The proper use of the symbol is debated; it is used to describe any cyclic pi system in some publications, or only those pi systems that obey Hückel's rule on others.
Arene synthesis
A reaction that forms an arene compound from an unsaturated or partially unsaturated cyclic precursor is simply called an aromatization.
Many laboratory methods exist for the organic synthesis of arenes from non-arene precursors.
Importance of aromatic compounds
Aromatic compounds play key roles in the biochemistry of all living things.
The four aromatic amino acids histidine, phenylalanine, tryptophan, and tyrosine each serve as one of the 20 basic building blocks of proteins.
Further, all 5 nucleotides (adenine, thymine, cytosine, guanine, and uracil) that make up the sequence of the genetic code in DNA and RNA are aromatic purines or pyrimidines.
As well as that, the molecule heme contains an aromatic system with 22 π electrons.
Chlorophyll also has a similar aromatic system.
Aromatic compounds are important in industry.
Key aromatic hydrocarbons of commercial interest are benzene, toluene, ortho-xylene and para-xylene.
About 35 million tonnes are produced worldwide every year.
They are extracted from complex mixtures obtained by the refining of oil or by distillation of coal tar.
They are used to produce a range of important chemicals and polymers, including styrene, phenol, aniline, polyester and nylon.
Types of aromatic compounds
Heterocyclics
In heterocyclic aromatics one or more of the atoms in the aromatic ring is of an element other than carbon.
Examples include pyridine, pyrazine, imidazole, pyrazole, oxazole, and thiophene.
Polycyclics
Polycyclic aromatic hydrocarbons are molecules with two or more simple aromatic rings fused together by sharing two neighboring carbon atoms.
Examples are naphthalene, anthracene and phenanthrene.
Substituted aromatics
Many chemical compounds are aromatic rings with other things attached.
Examples include trinitrotoluene (TNT), acetylsalicylic acid (aspirin), paracetamol, and the nucleotides of DNA.
Erich Probst (5 December 1927 – 16 March 1988) was an Austrian footballer.
He played as striker for different teams in Vienna and also abroad.
He started with Admira Wien being only 17 years old.
After a year with Vienna he signed with SK Rapid Wien.
In this time he won the Austrian Championship four times.
In his first season with Rapid he scored 28 goals in 23 matches.
Although he was always a top scorer he never shot the highest number of goals in the league.
After his time with Rapid he went to Wuppertaler SV in Germany.
After the relegation of Wuppertal he went on to Switzerland playing for FC Zürich.
In winter 1959 he came back to Austria to SV Austria Salzburg.
The club paid 90 000 Austrian schillings, which was the highest till this time.
He shot 15 goals and the team could stay in the top league.
During his time with Salzburg he played his last match in the national football team.
He was the first player of SV Austria Salzburg who ever played for the team.
In the 1960/61 season he was coach of SV Austria but not successful.
So he went on to play as striker again.
His last clubs were the SAK 1914 in Salzburg and First Vienna FC in Vienna.
At all he scored 150 goals in Austrias top league.
He played 19 times for the Austrian national football team and scored 17 goals.
His first match was on  27 May 1951 (4:0 versus Scotland)  In the qualification match for the FIFA World Cup 1954 versus Portugal he scored 5 goals for the 9:1 win.
He was member of the 1954 FIFA World Cup squad which reached the third place.
During the tournament he scored six goals and was together with Max Morlock of Germany and Josef Hügi of Switzerland second in the scorer list.
During his time abroad he was not player of the team.
But in 1960 he played his last match versus France (2:4) where he also scored his last goal for the team.
So he was the first national football team player coming from SV Austria Salzburg.
1951, 1952, 1954, 1956
Mitropa Cup (1):
Member of the Austrian team for the 1954 FIFA World Cup
Malcolm James McCormick (January 19, 1992 – September 7, 2018), known professionally as Mac Miller, was an American rapper, singer, songwriter, and record producer.