Private equity deals

Audax Group has acquired Advanced Dermatology and Cosmetic Surgery, a Maitland, Fla.-based dermatology-focused physician practice management company. No financial terms were disclosed, except that NXT Capital provided debt financing. Brentwood Capital Advisors advised ADCS on the transaction. www.audaxgroup.com

DeviceFidelity Inc., a Richardson, Texas–based provider of mobile contactless technologies, has raised an undisclosed amount of equity funding from Datacard Group Inc. and Dallas Equity Partners. www.devicefidelity.com

Rockland Capital has agreed to acquire substantially all the assets of Beacon Power Corp., an energy storage company that went bankrupt last October. No financial terms were disclosed for the deal, which includes a 20-megawatt flywheel energy storage plant in Stephentown, New York. www.beaconpower.com

Quantum Energy Partners has committed $300 million to launch Renaissance Offshore, a platform for acquiring offshore U.S. oil reserves. It will be led by Jeffrey Soine, a former executive with Australia’s Woodside Petroleum. www.quantumep.com

Want deal news in your inbox each morning? Then get Term Sheet!