Submitted on: 26 January 2019.
Revised on: 16 February 2019.
Accepted on: 04 March 2019.
PHYSICS WORLD---IOP PUBLISHING LTD
Submitted on: 15 April 2004.
Revised on: 10 May 2004.
Accepted on: 04 June 2004.
PHYSICS WORLD
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http://reply.papertrans.cn/3/247/24694/24694-34.png
Submitted on: 04 March 2016.
Revised on: 17 March 2016.
Accepted on: 02 April 2016.
PHYSICS WORLD
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