پرونده:Prototype synthetic quartz autoclave 1959.jpg
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Prototype_synthetic_quartz_autoclave_1959.jpg (۳۴۵ × ۴۱۷ پیکسل، اندازهٔ پرونده: ۵۱ کیلوبایت، نوع MIME پرونده: image/jpeg)
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خلاصه
| توضیح |
English: R. A. Sullivan and R. A. Ladice examining synthetic quartz crystals grown in the autoclave shown in Western Electric's pilot hydrothermal quartz plant in North Andover, Massachusetts in 1959. Until WW2, quartz crystals used in electronic equipment were natural crystals, mined in Brazil. Shortages due to military demand for quartz led to postwar efforts to culture synthetic quartz crystals. AT&T's Bell Labs first developed a process that was capable of industrial production, growing quartz crystals at high pressure and temperature in the autoclave shown. By the 1970s virtually all quartz used in the electronics industry was synthetic. |
| تاریخ | |
| منبع | Retrieved August 3, 2014 from Radio and Television News magazine, Ziff-Davis Publishing Co., Chicago, Vol. 61, No. 3, March 1959, p. 120 on American Radio History site |
| پدیدآور | نامعلوم |
| اجازه‌نامه (استفادهٔ مجدد از این پرونده) |
This 1959 issue of Radio and Television News magazine would have the copyright renewed in 1987. Online page scans of the Catalog of Copyright Entries, published by the US Copyright Office can be found here. [1] Search of the Renewals for Periodicals for 1978 to present show no renewal entries for Radio and Television News. Therefore the magazine's copyright was not renewed and it is in the public domain. |
اجازه‌نامه
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This work is in the public domain because it was published in the United States between 1929 and 1963, and although there may or may not have been a copyright notice, the copyright was not renewed. For further explanation, see Commons:Hirtle chart and the copyright renewal logs. Note that it may still be copyrighted in jurisdictions that do not apply the rule of the shorter term for US works (depending on the date of the author's death), such as Canada (70 years p.m.a.), Mainland China (50 years p.m.a., not Hong Kong or Macao), Germany (70 years p.m.a.), Mexico (100 years p.m.a.), Switzerland (70 years p.m.a.), and other countries with individual treaties.
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