Zone_refining_Bell_Labs_1954.jpg
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Summary
| Description |
English:
The first
zone refining
equipment from an advertisement by
Bell Telephone Laboratories
in an electronics magazine. Zone refining, a technique for purifying materials now widely used in the semiconductor industry, was invented by
William Gardner Pfann
in 1953. This was the first zone refining tube, with induction heating coiles.
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| Date | |
| Source | Retrieved July 20, 2014 from Radio and Television News magazine, Ziff-Davis Publishing Co., Chicago, Vol. 52, No. 4, October 1954, p. 6 on American Radio History site |
| Author | Unknown author |
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Permission
( Reusing this file ) |
This 1954 issue of Radio and Television News magazine would have the copyright renewed in 1982. 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 1982 show no renewal entries for Radio and Television News . Therefore the magazine's copyright was not renewed and it is in the public domain. |
Licensing
|
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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