I get a lot of original guest articles for publishing on my tech blog though my blog's 'write for us' page and guest posting forums. I don't want my blog's PR 3 to get affected by giving away a do-follow link in every article. I'll write my own articles from now on-wards. Is there a way to misuse the articles that I get to make money? How can I do it in a safe way without the contributors finding about it?