Pentaerythritol tetranitrate known as PENT, PENTA, TEN, corpent, or penthrite, is an explosive material. It is the nitrate ester of pentaerythritol, is structurally similar to nitroglycerin. Penta refers to the five carbon atoms of the neopentane skeleton. PETN is a powerful explosive material with a relative effectiveness factor of 1.66. When mixed with a plasticizer, PETN forms a plastic explosive. Along with RDX it is the main ingredient of Semtex. PETN is used as a vasodilator drug to treat certain heart conditions, such as for management of angina. Pentaerythritol tetranitrate was first prepared and patented in 1894 by the explosives manufacturer Rheinisch-Westfälische Sprengstoff A. G. of Cologne, Germany. The production of PETN started in 1912, when the improved method of production was patented by the German government. PETN was used by the German Military in World War I, it was used in the MG FF/M autocannons and many other weapon systems of the Luftwaffe in World War II in the high explosive Minengeschoß shell.
PETN is insoluble in water, weakly soluble in common nonpolar solvents such as aliphatic hydrocarbons or tetrachloromethane, but soluble in some other organic solvents in acetone and dimethylformamide. PETN forms eutectic mixtures with some liquid or molten aromatic nitro compounds, e.g. trinitrotoluene or tetryl. Due to steric hindrance of the adjacent neopentyl-like moiety, PETN is resistant to attack by many chemical reagents. Water at 100 °C or above causes hydrolysis to dinitrate; the chemical stability of PETN is because of the presence of PETN in aging weapons. A review has been published. Neutron radiation degrades PETN, producing carbon dioxide and some pentaerythritol dinitrate and trinitrate. Gamma radiation increases the thermal decomposition sensitivity of PETN, lowers melting point by few degrees Celsius, causes swelling of the samples. Like other nitrate esters, the primary degradation mechanism is the loss of nitrogen dioxide. Studies were performed on thermal decomposition of PETN.
In the environment, PETN undergoes biodegradation. Some bacteria denitrate PETN to trinitrate and dinitrate, further degraded. PETN has low volatility and low solubility in water, therefore has low bioavailability for most organisms, its toxicity is low, its transdermal absorption seems to be low. It poses a threat for aquatic organisms, it can be degraded to pentaerythritol by iron. Production is by the reaction of pentaerythritol with concentrated nitric acid to form a precipitate which can be recrystallized from acetone to give processable crystals. Variations of a method first published in US Patent 2,370,437 by Acken and Vyverberg form the basis of all current commercial production. PETN is manufactured by numerous manufacturers as a powder, or together with nitrocellulose and plasticizer as thin plasticized sheets. PETN residues are detectable in hair of people handling it; the highest residue retention is on black hair. The most common use of PETN is as an explosive with high brisance, it is more difficult to detonate than primary explosives, so dropping or igniting it will not cause an explosion, but is more sensitive to shock and friction than other secondary explosives such as TNT or tetryl.
Under certain conditions a deflagration to detonation transition can occur. It is used alone, but used in booster and bursting charges of small caliber ammunition, in upper charges of detonators in some land mines and shells, as the explosive core of detonation cord. PETN is the least stable of the common military explosives, but can be stored without significant deterioration for longer than nitroglycerin or nitrocellulose. During World War II, PETN was most used in exploding-bridgewire detonators for the atomic bombs; these exploding-bridgewire detonators gave more precise detonation, compared with primacord. PETN was used for these detonators because it was safer than primary explosives like lead azide: while it was sensitive, it would not detonate below a threshold amount of energy. Exploding bridgewires containing PETN remain used in current nuclear weapons. In spark detonators, PETN is used to avoid the need for primary explosives, its basic explosion characteristics are: Explosion energy: 5810 kJ/kg, so 1 kg of PETN has the energy of 1.24 kg TNT.
Detonation velocity: 8350 m/s, 7910 m/s, 7420 m/s, 8500 m/s Volume of gases produced: 790 dm3/kg Explosion temperature: 4230 °C Oxygen balance: −6.31 atom -g/kg Melting point: 141.3 °C, 140–141 °C Trauzl lead block test: 523 cm3 Critical diameter: 0.9 mm for PETN at 1 g/cm3, smaller for higher densities PETN is used in a number of compositions. It is a major ingredient of the Semtex plastic explosive, it is used as a component of pentolite, a 50/50 blend with TNT. The XTX8003 extrudable expl
Phewa Lake, Phewa Tal or Fewa Lake is a freshwater lake in Nepal called Baidam Tal located in the south of the Pokhara Valley that includes Pokhara city. The lake is stream-fed but a dam regulates the water reserves, the lake is classified as semi-natural freshwater lake, it is the second largest lake in Nepal. It is the most visited lake of Nepal, it is the only lake in Nepal to have a templeTal Barahi Temple at the central part of lake. Phewa lake is located at an altitude of 742 m and covers an area of about 4.43 km2. It has a maximum depth of 24 m. Maximum water capacity of the lake is 43,000,000 cubic metres; the Annapurna range on the north is only about 28 km away from the lake. The lake is famous for the reflection of mount Machhapuchhre and other mountain peaks of the Annapurna and Dhaulagiri ranges on its surface; the Tal Barahi Temple is situated on an island in the lake. Phewa lake and water sports is one of the major tourist attraction of Pokhara city and the north shore of the lake has developed into a tourist district called Lake-Side, with hotels and bars catering to the tourists.
The water from Phewa lake's outlet is used to generate electricity. The Phewa Power House is located about 1.5 km from the southern part of the Phewa lake. A part of the lake is used as commercial caged fisheries. Tal Barahi Temple, located at the center of Phewa Lake, is the most important religious monument of Pokhara; this two-storied pagoda is believed to be dedicated to one of the Hindu gods known as Vishnu. It gets crowded on Saturdays. Baidam is the eastern banks of Phewa lake known as Lakeside; this part contains endless strip of hotels, restaurants and souvenir shops. This side is one of the best known tourist area of Nepal, it is the starting point of the tour to Pokhara. Sarangkot and paragliding, Sarangkot is the only one place in Nepal for paragliding, from where you can fly over the Fewa lake. Annapurna Dhaulagiri Begnas Lake Rara Lake List of Nepal-related topics Phewa Lake Environment Awareness and Capacity Building Project Pokhara Photo Gallery Phewa Lake, photostory Phewa Lake View
Alfred Wallace Roome was an English film editor and occasional director. Born in London, in 1908, he first worked in the film industry as a film editor on the 1932 British comedy film Thark, he went on to edit comedies over the next forty years including many of the Aldwych Farces films, Will Hay films such as Boys Will Be Boys. He directed crime film My Brother's comedy film It's Not Cricket. In the latter years of his career he edited the Carry On series of films alongside the director, Gerald Thomas, he retired in 1975 after editing Carry on Behind. Roome married the actress Janice Adair on 20 February 1936; the couple had two children, a daughter and a son Christopher, killed in the King's Cross fire of 1987. Alfred Roome died on 19 November 1997, in Buckinghamshire, his granddaughter Olivia works in the film industry. My Brother's Keeper It's Not Cricket A Boy, a Girl and a Bike Obituary in The Independent