Stock Options and Warrants (Tables)

12 Months Ended

May. 31, 2015

Estimated Fair Value of Options and Warrants is determined using Black-Scholes Option Valuation Model

The estimated fair value of options and warrants is determined using the Black-Scholes option valuation model with the following weighted-average assumptions for the periods ended May 31, 2015 and 2014:

	2015	2014
Risk-free rate	0.73% - 1.10%	0.52% - 1.85%
Dividend yield	—	—
Volatility	74.36% - 81.16%	78.73% - 92.92%
Expected term	2.5-3.5 years	2.5-3.5 years
Grant date fair value	$0.33 - $0.60	$.40- $.67

Stock Option and Warrant Activity

The following table represents stock option and warrant activity for the periods ended May 31, 2015 and 2014:

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life in Years		Aggregate Intrinsic Value
Options and warrants outstanding - May 31, 2013		18,146,838		$	1.65		1.86	$	140,321
Granted		18,414,244			0.74		—		—
Exercised		(50,000	)		—		—		—
Forfeited/expired/cancelled		(5,704,721	)		1.49		—		—
Options and warrants outstanding - May 31, 2014		30,806,361			1.13		3.29		177,042
Granted		9,262,038			0.93		—		—
Exercised		(2,038,974	)		0.55		—		—
Forfeited/expired/cancelled		(7,020,510	)		1.76		—		—
Options and warrants outstanding - May 31, 2015		31,008,915			0.88		2.94		5,538,335
Outstanding exercisable - May 31, 2015		29,898,494		$	0.89		2.91	$	5,334,919