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Steric effects

Steric effects are nonbonding interactions that influence the shape and reactivity of ions and molecules. Steric effects complement electronic effects, which dictate shape and reactivity. Steric effects result from repulsive forces between overlapping electron clouds. Steric effects are exploited in applied and academic chemistry. Steric hindrance is a consequence of steric effects. Steric hindrance is the slowing of chemical reactions due to steric bulk, it is manifested in intermolecular reactions, whereas discussion of steric effects focus on intramolecular interactions. Steric hindrance is exploited to control selectivity, such as slowing unwanted side-reactions. Steric hindrance between adjacent groups can affect torsional bond angles. Steric hindrance is responsible for the observed shape of rotaxanes and the low rates of racemization of 2,2'-disubstituted biphenyl and binaphthyl derivatives; because steric effects have profound impact on properties, the steric properties of substituents have been assessed by numerous methods.

Relative rates of chemical reactions provide useful insights into the effects of the steric bulk of substituents. Under standard conditions methyl bromide solvolyzes 107 faster than does neopentyl bromide; the difference reflects the inhibition of attack on the compound with the sterically bulky 3C group. A values provide another measure of the bulk of substituents. A values are derived from equilibrium measurements of monosubstituted cyclohexanes; the extent that a substituent favors the equatorial position gives a measure of its bulk. Ceiling temperature is a measure of the steric properties of the monomers. T c is the temperature where the rate of depolymerization are equal. Sterically hindered monomers give polymers with low T c's, which are not useful. Ligand cone angles are measures of the size of ligands in coordination chemistry, it is defined as the solid angle formed with the metal at the vertex and the hydrogen atoms at the perimeter of the cone. Steric effects are critical to chemistry and pharmacology.

In organic chemistry, steric effects are nearly universal and affect the rates and activation energies of most chemical reactions to varying degrees. In biochemistry, steric effects are exploited in occurring molecules such as enzymes, where the catalytic site may be buried within a large protein structure. In pharmacology, steric effects determine how and at what rate a drug will interact with its target bio-molecules. Prominent Sterically Hindered Compounds Collision theory Reaction rate accelerate as result of steric hindrance in the Thorpe–Ingold effect Sterically induced reduction Intramolecular force Van der Waals strain known as steric strain Steric Effects at the Wayback Machine Steric: A Program to Calculate the Steric Size of Molecules at the Wayback Machine

Tony Award for Best Costume Design in a Musical

This is a list of winners and nominations for the Tony Award for Best Costume Design in a Musical for outstanding costume design of a musical. The award was first presented in 1961 after the category of Best Costume Design was divided into Costume Design in a Play and Costume Design in a Musical with each genre receiving its own award. In 2010, Santo Loquasto received a nomination for Best Costume Design for a Musical for Ragtime. Loquasto, nominated for the same show in the same category in 1998, was disqualified because the designs were predominantly recycled work from the earlier production. No replacement was made for the nomination. Tony Award for Best Costume Design in a Play Drama Desk Award for Outstanding Costume Design of a Musical Laurence Olivier Award for Best Costume Design Tony Awards Official site Tony Awards at Internet Broadway database Listing Tony Awards at

Common bottlenose dolphin

The common bottlenose dolphin, or Atlantic bottlenose dolphin, is the most well-known species from the family Delphinidae. Common bottlenose dolphins are the most familiar dolphins due to the wide exposure they receive in captivity in marine parks and dolphinaria, in movies and television programs; the common bottlenose dolphin is the largest species of the beaked dolphins. They inhabit temperate and tropical oceans throughout the world, are absent only from polar waters; until all bottlenose dolphins were considered as a single species, but now the Indo-Pacific bottlenose dolphin and Burrunan dolphin have been split from the common bottlenose dolphin. While named as the bottlenose dolphin, this term is now applied to the genus as a whole; the dolphins inhabit temperate seas worldwide. As considerable genetic variation has been described among members of this species between neighboring populations, many experts consider that additional species may be recognized; the common bottlenose dolphin is grey in color and may be between 2 and 4 m long, weighs between 150 and 650 kg.

Males are larger and heavier than females. In most parts of the world, the adult's length is between 2.5 and 3.5 m with weight ranging between 200 and 500 kg. Dolphins have a short and well-defined snout that looks like an old-fashioned gin bottle, the source for their common name. Like all whales and dolphins, the snout is not a functional nose, their necks are more flexible than other dolphins' due to five of their seven vertebrae not being fused together as is seen in other dolphin species. The common bottlenose dolphin has a bigger brain than humans. Numerous investigations of bottlenose dolphin intelligence include tests of mimicry, use of artificial language, object categorization, self-recognition; this intelligence has driven considerable interaction with humans. Common bottlenose dolphins are popular in aquarium shows and television programs such as Flipper, they have been trained for military uses such as locating sea mines or detecting and marking enemy divers, as for example in the U.

S. Navy Marine Mammal Program. In some areas, they cooperate with local fishermen by driving fish toward the fishermen and eating the fish that escape the fishermen's nets; as the social animal, common bottlenose dolphins live in groups called pods that number about 15 individuals, but group size varies from pairs of dolphins to over 100 or occasionally over 1000 animals for short periods of time. The type of group is include, their diets consist of eels, shrimp and a wide variety of fishes. They do not chew their food. Dolphin groups work as a team to harvest schools of fish, though they hunt individually. Dolphins search for prey using echolocation, a form of sonar; the diet of common bottlenose dolphin varies depending on area. Along the U. S. Atlantic coast, the main prey includes Atlantic croakers, ‘spot’ fish, American silver perch, while dolphins in South Africa feed on African massbankers, olive grunters, pandora. Dolphins use sound for communication, including squeaks emitted from the blowhole, whistles emitted from nasal sacs below the blowhole, sounds emitted through body language, such as leaping from the water and slapping their tails on the water.

Their heads contain an oily substance that both acts as an acoustic lens and protects the brain case. They emit clicking sounds and listen for the return echoes to determine the location and shape of nearby items, including potential prey. Mating behavior of bottlenose dolphin is polygamous. Although they can breed throughout the year, it occurs in spring. Males form alliances to seek an estrous female. For a chance to mate with the female, males separate the female from her home range. Females bear a calf every three to six years. After a year-long gestation period, females bear a single calf. Newborn calves weigh between 15 and 30 kg, they can live as long as 40–50 years. The calf suckling lasts 20 months. Sexual maturity varies by population, ranges from 5–14 years of age; the average life expectancy of common bottlenose dolphins is about 17 years old, but in captivity they have been known to live to up to 51 years old. The common bottlenose dolphin can be found in the temperate and tropical oceans worldwide.

The global population has been estimated at 600,000. Some bottlenose populations live closer to the shore and others live further out to sea. Offshore populations are larger and have proportionally shorter fins and beaks. Offshore populations can migrate up to 4,200 km in a season, but inshore populations tend to move less. However, some inshore populations make long migrations in response to El Niño events; the species has occurred as far as 50° north in eastern Pacific waters as a result of warm water events. The coastal dolphins appear to adapt to shallow waters, it has larger flippers, for maneuverability and heat dispersal. They can be found in harbors, bays and estuaries. Offshore dolphins, are adapted to cooler, deeper waters. Certain qualities in their blood suggest they ar

Aerocar (1905 automobile)

The Aerocar was an American automobile built from 1905 to 1908 in Detroit, Michigan. Backed by Henry Ford's former partner, coal merchant Alexander Malcomson, the short-lived company offered an air-cooled 24 hp four-cylinder luxury car which sold for $2800; the factory was sold to Hudson Motor Car Company. In 1906, the Model A was powered by a Reeves four-cylinder, air-cooled engine, it came with a "Standard Extension Black Top" and two gas headlights as well as "Full Oil Lamp Equipment." The automobile had Hartford shock absorbers, Gabriel horn and a speedometer. It came with an extra tire and inner tube in a waterproof case with attaching irons, robe-rail and a footrest in Tonneau. A toolbox with full equipment was attached to the exterior running board; the machine cost $2,800. The air-cooled engine was replaced by a Reeves water-cooled model. Brass Era car actress Frances Starr at the wheel of one of the company's luxury cars

Richard A. Greenwood

Richard A. Greenwood is a Republican member of the Utah House of Representatives, representing District 12. In 2007, Greenwood was appointed to replace D. Gregg Buxton, who resigned to take a position in the executive branch of the Utah government. Greenwood was born on November 6 in Utah. Greenwood attended Weber State University. Prior to his time in the legislature, Greenwood worked as a deputy for the Weber County Sheriff’s Office. Greenwood was appointed to the Legislature in 2007. In 2012, Greenwood was unopposed in the Republican Primary and won his General Election nomination with a 72.1% majority. During the 2013 and 2014 legislative sessions, Greenwood served on the Administrative Rules Review Committee, the Executive Offices and Criminal Justice Appropriations Subcommittee, the House Economic Development and Workforce Services Committee, the House Law Enforcement and Criminal Justice Committee. During the interim, Greenwood served on the Law Enforcement and Criminal Justice Interim Committee, as well as the Political Subdivisions Interim Committee.

On April 2, 2014, Greenwood announced. Greenwood floor sponsored SB0120S03 Shelter Animal Vaccine Amendments and SB0144 Driver License Modifications. Official page at the Utah State Legislature Profile at Project Vote Smart Richard Greenwood at Ballotpedia Sponsored Legislation Campaign Contributions at Sunlight Foundation


Kagnout is a village in Casamance, Senegal. It is located near the left bank of the estuary of the Casamance River. On March 25, 1851, the leaders of Kagnout permanently ceded the island of Carabane to France; the village is part of the rural community of Mlomp in Ziguinchor. The nearest towns are Carabane, Kabounkoute, Loudia Diola and Samatit. Muriel Scibilia. La Casamance ouvre ses cases. Tourisme au Sénégal. L’Harmattan. P. 174. ISBN 2-85802-676-9. Louis-Vincent Thomas. Les Diola. Essai d’analyse fonctionnelle sur une population de Basse-Casamance. Dakar: IFAN, Université de Dakar. P. 821. Maps and airports for Kagnout