1,1,1-Trichloro-2,2,2-trifluoroethane

Trichlorotrifluoroethane, also called 1,1,1-Trichloro-2,2,2-trifluoroethane or CFC-113a is a chlorofluorocarbon (CFC). It has the formula Cl₃C-CF₃.

Environmental effects

Ozone depletion

It is one of four man-made chemicals newly discovered in the atmosphere by a team at the University of East Anglia. But CFC-113a is the only known CFC whose abundance in the atmosphere is still growing. CFC-113a seems to have been accumulating unabated since 1960. Its source remains a mystery, but illegal manufacturing in China is suspected by some. Between 2010 and 2012, emissions of the gas jumped by 45 percent.

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References

R-390A

The R-390A /URR is a general coverage HF radio communications receiver designed by Collins Radio Company for the US military.

History

The R-390A military shortwave radio receiver was the result of a project undertaken by the U.S. Army Signal Corps in 1954 to replace the existing R-390 receiver then in use. The R-390 had done its job so well that the Corps decided continued use of this type of receiver necessitated an improved, reduced-cost version. There are many references to the R390A in the open literature during this period; a picture of the receiver appeared in the May 1959 issue of the amateur radio magazine QST.

Total production of the R-390A (as determined by the high serial numbers noted) is over 55,000 units. Initial production started in 1955 and ran through approximately 1970, and then was restarted in 1984 by Fowler Industries for Avondale Shipyards. Manufacturers and their approximate production numbers are:

Dichlorodifluoroethylene

A dichlorodifluoroethylene (systematically named dichlorodifluoroethene) is one of three compounds with the chemical formula C
2Cl
2F
2. Dichlorodifluoroethylenes are colourless gases, and are some of the simplest chlorodifluoroalkenes.

The structural isomers are used as intermediates or precursors in the production of other industrial chemicals.

1,1-Dichloro-2,2-difluoroethylene

1,1-Dichloro-2,2-difluoroethylene is a low-boiling liquid that is used a refrigerant. It may also be used as a solvent, but has practical limitations as such, because of its low boiling point (commercial listings, 19 °C; lit. 17 °C).

It is regarded as a hazardous chemical for being toxic by inhalation (see MSDS), and a low-boiling liquid, and it causes irritation when it comes into contact with the skin and mucous membranes. Its ASHRAE number is R-1112a, and its CAS number is 79-35-6. Concentrated 1,1-dichloro-2,2-difluoroethylene can be ignited with ease in the laboratory.

cis- And trans-1,2-dichloro-1,2-difluoroethylene

Aura clan

The Aura are a Muslim Jat tribe, found mainly in Gujar Khan Tehsil of Rawalpindi District. Chak 21 S.B. is large settlement of the Aura in Sargodha District. These Aura are immigrants from Gujar Khan Tehsil who were settled in the Sargodha region in the 19th Century. Other villages include Balakhar in Rawalpindi District and Abdullahpur in Jhelum District.

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References

Aura (Miles Davis album)

Aura is a concept album by Miles Davis, produced by Danish composer/trumpeter Palle Mikkelborg, released in 1989. All compositions and arrangements are by Mikkelborg, who created the suite in tribute when Davis received the Léonie Sonning Music Prize in December 1984, the year Decoy was released.

Background

The main theme consists of 10 notes, yielded by the letters "M-I-L-E-S-D-A-V-I-S" (see BACH motif, and Schoenberg hexachord "EsCHBEG", and the chart at Musical notes#Accidentals). It is introduced at the beginning over a sustained chord of these same notes. The following 9 movements of the suite represent the colours Mikkelborg sees in Miles's aura.

The music is scored for an extended jazz big band, and the core of the band is formed by the Danish Radio's Big Band, featuring Niels-Henning Ørsted Pedersen, Thomas Clausen and Marilyn Mazur. Notable international guests such as John McLaughlin and Davis' nephew Vince Wilburn are featured. The sessions took place in Copenhagen in 1985 at Davis' own initiative, as he had been very honored and satisfied with the suite. It was the first time Miles Davis had recorded with a big band for over 20 years. Aura, however, is not a conventional big band jazz album. The music is perhaps best categorized as fusion jazz with a strong flavor of modern classical music, as many of the orchestral passages reveal Mikkelborg's inspiration from composers like Olivier Messiaen and Charles Ives.

Bowers & Wilkins

Bowers & Wilkins, or B&W, is a British company that produces audio equipment, most notably loudspeakers. B&W was founded in 1966 by John Bowers at Worthing, West Sussex, England. Currently, B&W, while still based in Worthing, is part of the B&W Group Ltd., which also includes audio equipment manufacturers Rotel and Classé.

B&W previously offered a range of electronics, like amplifiers, under the Aura brand, but it was discontinued in 1997. Other sub-brands were 'John Bowers' for the Active One loudspeaker and preamp and 'Rock Solid' for a lifestyle speaker range. The B&W 'Blue Room' brand for 'Pod' speakers disappeared as these are currently produced and sold by Scandyna. From 1988 to 1996 B&W ran their own record label.

Technology, Research and Development

Research and development has been a core activity within B&W, stimulated and exercised by its founder John Bowers. From the start of the company, earnings were invested in new product development.

In 1982 the company opened a dedicated, purpose-built research centre titled 'SRE' or 'Steyning Research Establishment' in Steyning, about 10 miles from Worthing. The buildings were fit for audio-related work since they were previously used by SME, the English tonearm designer who felt the downturn in tonearm sales due to the introduction of the new digital media CD. SRE housed a prototype shop and listening rooms, ranging from semi-anechoic to typical small living rooms. Also available was advanced equipment like a laser interferometer and PDP-11/35 computer.