Outside the U.S., Amex has taken a step away from its closed loop model where it issues its own credit cards and also acts as the acquirer for merchants accepting the card.

FORBES: Quick Take

There are many areas of overlap between biomimicry and "cradle-to-cradle" particularly in the way that ecosystems present a great model of closed loop systems in which any waste from one organism becomes the nutrient for something else.

CNN: STORY HIGHLIGHTS

American Express has successfully implemented its spend-centric model and closed-loop network to achieve growth over the last few years and was one of the few financial companies to come out of the economic crisis of 2008 virtually unscathed.

FORBES: Quick Take

American Express says it is uniquely positioned to offer the service thanks to its "closed-loop" business model in which it acts as card issuer, merchant acquirer and payment processing operator.

BBC: Foursquare and Amex join forces in UK to offer discounts

The gravity-based system responded as it was designed to, circulating water and steam in a continuous loop to keep the scale-model reactor at a safe temperature automatically.

CNN: Today/Tomorrow - Helping nuclear plants keep their cool