If I understand your question... 
$string=~s/([b-w]+)([^a]+)([a]+)/uc($1).$2.uc($3)/e;

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Or, without putting eval code in the replacement: 
$string=~s/([b-w]+)([^a]+)([a]+)/\U$1\E$2\U$3/;

[download]

In reply to Re: How to do multiple substitutions with one RegEx? by graff
in thread How to do multiple substitutions with one RegEx? by vennila

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