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Paris Air Show

The Paris Air Show is the largest air show and aerospace-industry exhibition event in the world, measured by number of exhibitors and size of exhibit space. In second place is UK's Farnborough, followed by Dubai Air Show or Singapore Airshow; the latest was the 52nd Air Show, held from 19 to 25 June 2017, attended by 3,450 journalists, 142,000 professionals and 180,000 general public visitors. It claims to be the world's calendar-oldest air show. Established in 1909, it has been held every odd year since 1949 at Paris–Le Bourget Airport in north Paris, France, it is a large trade fair, demonstrating military and civilian aircraft, is attended by many military forces and the major aircraft manufacturers announcing major aircraft sales. It starts with four professional days and is opened to the general public followed from Friday to Sunday; the format is similar to Farnborough and the ILA, both staged in years. It is organised by the French aerospace industry's primary representative body, the Groupement des industries françaises aéronautiques et spatiales.

The Paris Air Show traces its history back to the first decade of the 20th century. In 1908 a section of the Paris Motor Show was dedicated to aircraft; the following year, a dedicated air show was held at the Grand Palais from 25 September to 17 October, during which 100,000 visitors turned out to see products and innovations from 380 exhibitors. There were four further shows before the First World War; the show restarted in 1919, from 1924 it was held every two years before being interrupted again by the Second World War. It restarted in 1946 and since 1949, has been held in every odd year; the air show continued to be held at the Grand Palais, from 1949 flying demonstrations were staged at Paris Orly Airport. In 1953, the show was relocated from the Grand Palais to Le Bourget; the show was drawing international notice in the 1960s. Since the 1970s, the show has emerged as the main international reference of the aeronautical sector; the 1967 air show was opened by French President Charles de Gaulle, who toured the exhibits and shook hands with two Soviet cosmonauts and two American astronauts.

Prominently displayed by the Soviet Union was a three-stage Vostok rocket, such as the one that had carried Yuri Gagarin into space on April 12, 1961. The "extraordinarily powerful" Vostok was downplayed by American missile experts as "rather old and unsophisticated.". The American exhibit, the largest at the fair, featured the F-111 swing-wing fighter bomber, a replica of Charles Lindbergh's Spirit of St. Louis, and the Ling-Temco-Vought XC-142A, a cargo plane capable of a vertical takeoff and landing. A full-size model of the supersonic Concorde was displayed by the French and British, auguring its successful first flight on March 2, 1969. "The largest plane in the world," the Boeing 747 jet airliner, arrived on June 3, after flying non-stop from Seattle and the Apollo 8 command module, charred by its re-entry, was there flanked by the Apollo 9 astronauts, but the most-viewed exhibit was the supersonic Concorde, which made its first flight over Paris as the show opened. The Soviet TU-144 supersonic airliner was flown to Le Bourget for the 1971 show, drawing comparisons with the French Concorde.

Landing with the Concorde was the American Lockheed C-5A Galaxy. The crash of the Soviet Tu-144, see below, overshadowed the 1973 show, otherwise characterized by "There was nothing new", although the flying was memorable, there were a great many exhibits. One hundred and eighty-two aircraft were scheduled for appearance. Despite restrictions that followed the TU-144 crash in 1973, a day of flying pleased viewers. In particular, the American YF-16 and the French Mirage F-1E competed in turn before a critical audience. Days Belgium became the fourth European nation to choose the YF-16 over the F-1E. Celebration of Charles Lindbergh's trans-Atlantic flight to Le Bourget fifty years ago recalled that historic event. Anne Morrow Lindbergh, Lindbergh's widow, attended the ceremony along with early trans-Atlantic pilots, Maurice Bellonte and Armand Lotti. Recent extension of coastal limits to 200 nautical miles has produced new maritime-reconnaissance aircraft; the crash of a Fairchild A-10 tank-destroyer led to tightened rules on air show demonstrations.

Two airliners, the Airbus A310 and the Boeing 767, are competing for the international market, but neither will carry passengers before 1982. The Westland WG30 transport helicopter shows promise. "The Mirage 4000 remains a question mark" despite being "surely the main highlight this year at Le Bourget." Exhibiting at the show, Boeing, McDonnell Douglas/Fokker vie for the 150-seat airline market, while Rolls Royce/Japan, General Electric/Snecma, Pratt & Whitney contest for their engines. The Northrop F-5G Tigershark mockup was on display and expected to fly in 1982 with delivery the following year. A novelty was Air Transat, a light aircraft trans-Atlantic race from Le Bourget to Sikorsky Memorial Airport, Bridgeport and back, won by a twin engine Piper Navaho and a Beechcraft Bonanza; the American Space Shuttle Enterprise was flown around Paris and towered over other exhibits, but "much more intriguing" were replicas of two twin-engined fighters, the British Aerospace ACA and French Dassault Breguet ACX.

Sales of Boeing 757 and Airbus A310 airliners to Singapore Airlines were welcome news during an ongoing recession. The Soviet Antonov An-124 Ruslan military heavy lifter was the largest exhibit in 1985. Propfan engines stirred interest. Reflecting the upturn in the economy and Airbus announced new contracts totaling as much as $1,700 million; the Hubble Space Telescope sh

Hayes F.C.

Hayes Football Club was an English association football club based in Hayes, Greater London. The club started out as Botwell Mission in 1909, adopting the name Hayes F. C. in 1929. The team nickname, The Missioners, was a salute to the history of the team; the club played in the Conference South for their last few seasons in existence. Their home stadium was Church Road which seated 500 with a total capacity of 6,500; the team was recognised by their white striped shirt. The club's last manager was Kevin Hill, who got the job on a full-time basis after steering the team clear of relegation after the departure of Willy Wordsworth towards the end of the 2006–07 season. Wordsworth had been unable to emulate the success of his predecessor, the regarded Terry Brown, who left to take a vacancy at Aldershot Town in 2002. Hayes merged with Yeading F. C. on 18 May 2007 to form the new club Hayes & Yeading United, who continued to play in the Conference South. Hayes were formed in 1909 by Eileen Shackle, who wished to create a club to encourage boys to participate in sport as well as encourage their religious convictions.

Their original name, Botwell Mission, derived from the fact that they changed at the small mission church and stored their kit there. The club was runner-up in the FA Amateur Cup to Wycombe Wanderers in 1931. 32,000 watched Hayes succumb to a late goal at Highbury. After winning the Isthmian League in 1996, Hayes had a six-year stint in the Conference National, spanning from 1996 to 2002, they reached their highest league-finish in 1999, ending the season just seven points away from promotion to the Football League, via a Conference championship. Hayes reached the FA Cup second-round on four occasions; the club claimed some respectable cup triumphs, among the most noteworthy being those against Fulham, Bristol Rovers and Cardiff City. In 1999 they missed out on a lucrative third-round tie with Chelsea after defeat in extra time to Hull City. An FA Cup tie against Reading in 1972 brought Missioners player Robin Friday to the attention of a wider public, he was signed by Reading soon after. Friday was voted Cardiff City's ` Cult Hero' on the BBC's Football Focus.

Church Road saw the start of the career of a number of players who went on to higher levels, among them Les Ferdinand, Cyrille Regis, Blackburn Rovers striker Jason Roberts, Crewe Alexandra's Justin Cochrane and French goalkeeper Bertrand Bossu, who famously scored an injury time equaliser at St Albans City in February 2003. Middlesex Senior CupWinners: 1919–20, 1920–21, 1925–26, 1930–31, 1935–36, 1949–50, 1981–82, 1995–96, 1999–2000 Runners-up: 1922–23, 1936–37, 1939–40, 1948–49, 1950–51, 1967–68, 1980–81, 1986–87, 2005–06, 2006–07Middlesex Senior Charity CupWinners: 1920–21, 1922–23, 1923–24, 1925–26, 1928–29, 1932–33, 1933–34, 1948–49, 1954–55, 1962–63, 1970–71, 1971–72, 1972–73, 1974–75, 1990–91 Runners-up: 1921–22, 1938–39, 1947–48, 1958–59, 1963–64, 1964–65, 1979–80Great Western Suburban LeagueWinners: 1920–21,1921–22,1922–23,1923–24 Runners-up: 1919–20Spartan League Division 1Winners: 1927–28 Runners-up: 1925–26Athenian LeagueWinners: 1956–57 Runners-up: 1931–32, 1949–50Isthmian League Premier DivisionWinners: 1995–96 FA Cup best performance: second round proper replay – 1972–73, 1999–2000 FA Trophy best performance: quarter-finals – 1978–79, 1997–98 FA Amateur Cup best performance: runners-up – 1930–31 Official website Unofficial Supporters website

Stacking (chemistry)

In chemistry, pi stacking refers to attractive, noncovalent interactions between aromatic rings, since they contain pi bonds. These interactions are important in nucleobase stacking within DNA and RNA molecules, protein folding, template-directed synthesis, materials science, molecular recognition, although new research suggests that pi stacking may not be operative in some of these applications. Despite intense experimental and theoretical interest, there is no unified description of the factors that contribute to pi stacking interactions; the benzene dimer is the prototypical system for the study of pi stacking, is experimentally bound by 8–12 kJ/mol in the gas phase with a separation of 4.96 Å between the centers of mass for the T-shaped dimer. The small binding energy makes the benzene dimer difficult to study experimentally, the dimer itself is only stable at low temperatures and is prone to cluster. Other evidence for pi stacking comes from X-ray crystal structures. Perpendicular and offset parallel configurations can be observed in the crystal structures of many simple aromatic compounds.

Similar offset parallel or perpendicular geometries were observed in a survey of high-resolution x-ray protein crystal structures in the Protein Data Bank. Analysis of the aromatic amino acids phenylalanine, tyrosine and tryptophan indicates that dimers of these side chains have many possible stabilizing interactions at distances larger than the average van der Waals radii; the preferred geometries of the benzene dimer have been modeled at a high level of theory with MP2-R12/A computations and large counterpoise-corrected aug-cc-PVTZ basis sets. The two most stable conformations are the parallel displaced and T-shaped, which are isoenergetic. In contrast, the sandwich configuration maximizes overlap of the pi system, which destabilizes the interaction; the sandwich configuration represents an energetic saddle point, consistent with the relative rarity of this configuration in x-ray crystal data. The relative binding energies of these three geometric configurations of the benzene dimer can be explained by a balance of quadrupole/quadrupole and London dispersion forces.

While benzene does not have a dipole moment, it has a strong quadrupole moment. The local C–H dipole means that there is positive charge on the atoms in the ring and a correspondingly negative charge representing an electron cloud above and below the ring; the quadrupole moment is reversed for hexafluorobenzene due to the electronegativity of fluorine. The benzene dimer in the sandwich configuration is stabilized by London dispersion forces but destabilized by repulsive quadrupole/quadrupole interactions. By offsetting one of the benzene rings, the parallel displaced configuration reduces these repulsive interactions and is stabilized; the large polarizability of aromatic rings lead to dispersive interactions as major contribution to stacking effects. These play a major role for interactions of nucleobases e.g. in DNS. The T-shaped configuration enjoys favorable quadrupole/quadrupole interactions, as the positive quadrupole of one benzene ring interacts with the negative quadrupole of the other.

The benzene rings are furthest apart in this configuration, so the favorable quadrupole/quadrupole interactions evidently compensate for diminished dispersion forces. The ability to fine-tune pi stacking interactions would be useful in numerous synthetic efforts. One example would be to increase the binding affinity of a small-molecule inhibitor to an enzyme pocket containing aromatic residues; the effects of heteroatoms and substituents on pi stacking interactions is difficult to model and a matter of debate. An early model for the role of substituents in pi stacking interactions was proposed by Hunter and Sanders, they used a simple mathematical model based on sigma and pi atomic charges, relative orientations, van der Waals interactions to qualitatively determine that electrostatics are dominant in substituent effects. According to their model, electron-withdrawing groups reduce the negative quadrupole of the aromatic ring and thereby favor parallel displaced and sandwich conformations. Contrastingly, electron donating groups increase the negative quadrupole, which may increase the interaction strength in a T-shaped configuration with the proper geometry.

Based on this model, the authors proposed a set of rules governing pi stacking interactions which prevailed until more sophisticated computations were applied. Experimental evidence for the Hunter–Sanders model was provided by Siegel et al. using a series of substituted syn- and anti-1,8-di-o-tolylnaphthalenes. In these compounds the aryl groups "face-off" in a stacked geometry due to steric crowding, the barrier to epimerization was measured by nuclear magnetic resonance spectroscopy; the authors reported that aryl rings with electron-withdrawing substituents had higher barriers to rotation. The interpretation of this result was that these groups reduced the electron density of the aromatic rings, allowing more favorable sandwich pi stacking interactions and thus a higher barrier. In other words, the electron-withdrawing groups resulted in "less unfavorable" electrostatic interactions in the ground state. Hunter et al. applied a more sophisticated chemical double mutant cycle with a hydrogen-bonded "zipper" to the issue of substituent effects in pi stacking interactions.

This technique has been used to study a multitude of noncovalent interactions. The single mutation, in this case changing a substituent on an aromatic ring, results in secondary effects such as a change in hydrogen bond strength; the double mutation quantifies these secondary interactions, such that a weak interaction of interest can be dissected from the array. Their results indicate that more electron-withdrawing s