But modern times, many technics have quit the mainstream stage of history for various reasons, and are replaced by metal surface technics that will adapt to contemporary society.

但到了现代，由于各种原因，许多工艺已经退出历史主流舞台，取而代之的是更适合现代社会的金属表面工艺。

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Mudrian says that, freed from the pressure of the mainstream, metal went underground.

NPR: Kicking and Screaming, Metal Back in Music Spotlight

Developed to remove arsenic from soldiers gassed during World War I, the method is used in mainstream medicine for rare cases of acute heavy metal poisoning.

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