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4H (other)
4H may refer to: *4-H, a youth organization administered by the USDA *Curtiss JN-4H, an American biplane *4H, a Washington, D.C. Metrobus route, in the United States *4H-pyran *4H-SiC, one of the polymorphs of silicon carbide * Hydrogen-4 (4H, or quadrium), an isotope of hydrogen *4H, IATA code for United Airways, a Bangladeshi airline *4H disease, an early name for AIDS since the syndrome seemed to affect heroin users, homosexuals, hemophiliacs, and Haitians *4H, the production code for the 1975 ''Doctor Who'' serial ''Planet of Evil ''Planet of Evil'' is the second serial of the 13th season of the British science fiction television series ''Doctor Who''. It was first broadcast in four weekly parts on BBC1 from 27 September to 18 October 1975. The serial is set on and ab ...'' See also * H4 (other) {{Letter-NumberCombDisambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Curtiss JN-4
The Curtiss JN "Jenny" was a series of biplanes built by the Curtiss Aeroplane Company of Hammondsport, New York, later the Curtiss Aeroplane and Motor Company. Although the Curtiss JN series was originally produced as a training aircraft for the US Army, the "Jenny" (the common nickname derived from "JN") continued after World War I as a civil aircraft, as it became the "backbone of American post war ivilaviation". Thousands of surplus Jennys were sold at bargain prices to private owners in the years after the war and became central to the barnstorming era that helped awaken the US to civil aviation through much of the 1920s. Design and development Curtiss combined the best features of the model J and model N trainers, built for the US Army and US Navy, and began producing the JN or "Jenny" series of aircraft in 1915. Curtiss built only a limited number of the JN-1 and JN-2 biplanes. The design was commissioned by Glenn Curtiss from Englishman Benjamin Douglas Thomas, forme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
List Of Metrobus Routes (Washington, D
List of Metrobus routes may refer to: * List of Metrobus routes (Miami-Dade County) Over 100 Metrobus routes are operated by Miami-Dade Transit with some routes contracted by LSF, serving Miami-Dade County, Florida and connecting with several routes in adjacent counties. Most routes are identified by number or letter, however s ... * List of Metrobus routes (Washington, D.C.) {{disambig ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pyran
In chemistry, pyran, or oxine, is a six-membered heterocyclic, non-aromatic ring, consisting of five carbon atoms and one oxygen atom and containing two double bonds. The molecular formula is C5H6O. There are two isomers of pyran that differ by the location of the double bonds. In 2''H''-pyran, the saturated carbon is at position 2, whereas, in 4''H''-pyran, the saturated carbon is at position 4. 4''H''-Pyran was first isolated and characterized in 1962 via pyrolysis of 2-acetoxy-3,4-dihydro-2''H''-pyran. It was found too unstable, particularly in the presence of air. 4''H''-pyran easily disproportionates to the corresponding dihydropyran and the pyrylium ion, which is easily hydrolyzed in aqueous medium. Although the pyrans themselves have little significance in chemistry, many of their derivatives are important biological molecules, such as the pyranoflavonoids. The term pyran is also often applied to the saturated ring analog, which is more properly referred to as tet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polymorphs Of Silicon Carbide
Many compound materials exhibit polymorphism, that is they can exist in different structures called polymorphs. Silicon carbide (SiC) is unique in this regard as more than 250 polymorphs of silicon carbide had been identified by 2006, with some of them having a lattice constant as long as 301.5 nm, about one thousand times the usual SiC lattice spacings. The polymorphs of SiC include various amorphous phases observed in thin films and fibers, as well as a large family of similar crystalline structures called polytypes. They are variations of the same chemical compound that are identical in two dimensions and differ in the third. Thus, they can be viewed as layers stacked in a certain sequence. The atoms of those layers can be arranged in three configurations, A, B or C, to achieve closest packing. The stacking sequence of those configurations defines the crystal structure, where the unit cell is the shortest periodically repeated sequence of the stacking sequence. This descri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrogen-4
Hydrogen (1H) has three naturally occurring isotopes, sometimes denoted , , and . and are stable, while has a half-life of years. Heavier isotopes also exist, all of which are synthetic and have a half-life of less than one zeptosecond (10−21 s). Of these, is the least stable, while is the most. Hydrogen is the only element whose isotopes have different names that remain in common use today: the (or hydrogen-2) isotope is deuterium and the (or hydrogen-3) isotope is tritium. The symbols D and T are sometimes used for deuterium and tritium. The IUPAC accepts the D and T symbols, but recommends using standard isotopic symbols ( and ) instead to avoid confusion in the alphabetic sorting of chemical formulas. The isotope , with no neutrons, is sometimes called protium. (During the early study of radioactivity, some other heavy radioactive isotopes were given names, but such names are rarely used today.) List of isotopes , - , , 1 , 0 , , colspan=3 align ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
United Airways
United Airways (BD) Ltd. (, ), operated as United Airways ( bn, ইউনাইটেড এয়ারওয়েজ), was a Bangladeshi airline headquartered in Uttara, Dhaka. It operated flights from its main hub at Shahjalal International Airport in Dhaka and secondary hub at Shah Amanat International Airport in Chittagong. It was founded in 2005 and began flights on 10 July 2007 with a Bombardier Dash 8–100, purchased from Island Air. United Airways was the first listed company in the aviation sector of Bangladesh; it became listed in July 2010. The airline was often criticised for their poor service due to frequent delays, flight suspensions and poor in-flight amenities. In September 2014, the airline temporarily suspended its operations for three days following a conflict among its board of directors and a financial crisis. The airline ceased all operations on 6 March 2016, after a previous gap in service from mid-January to 24 February of that year. History Unite ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
AIDS
Human immunodeficiency virus infection and acquired immunodeficiency syndrome (HIV/AIDS) is a spectrum of conditions caused by infection with the human immunodeficiency virus (HIV), a retrovirus. Following initial infection an individual may not notice any symptoms, or may experience a brief period of influenza-like illness. Typically, this is followed by a prolonged incubation period with no symptoms. If the infection progresses, it interferes more with the immune system, increasing the risk of developing common infections such as tuberculosis, as well as other opportunistic infections, and tumors which are rare in people who have normal immune function. These late symptoms of infection are referred to as acquired immunodeficiency syndrome (AIDS). This stage is often also associated with Cachexia, unintended weight loss. HIV is #Transmission, spread primarily by unprotected sex (including anal sex, anal and vaginal sex), contaminated blood transfusions, hypodermic needles, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planet Of Evil
''Planet of Evil'' is the second serial of the 13th season of the British science fiction television series ''Doctor Who''. It was first broadcast in four weekly parts on BBC1 from 27 September to 18 October 1975. The serial is set on and above the planet Zeta Minor, the last undiscovered planet in the known universe, more than 30,000 years in the future. In the serial, the Morestran geologist Sorenson (Frederick Jaeger) seeks to exploit the antimatter minerals on the planet to use as a power source for his own planet when he and the military mission looking for him are attacked by a creature from a universe of anti-matter. Plot The TARDIS picks up a distress call and the Fourth Doctor and Sarah Jane Smith arrive on the planet Zeta Minor. There they discover that a Morestran geological expedition has fallen prey to an unseen killer and only the leader, Professor Sorenson, remains alive. A military mission from Morestra has also arrived to investigate. At first they suspec ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
