Annual report pursuant to Section 13 and 15(d)

Stock Options and Warrants (Detail)

v3.2.0.727
Stock Options and Warrants (Detail) - USD ($)
 12 Months Ended
May. 31, 2015
May. 31, 2014
May. 31, 2013
Stock option and warrant activity      
Options and warrants outstanding, Number of Shares 30,806,361 18,146,838  
Granted, Number of Shares 9,262,038 18,414,244  
Exercised, Number of Shares (2,038,974) (50,000)  
Forfeited /expired/ cancelled, Number of Shares (7,020,510) (5,704,721)  
Options and warrants outstanding, Number of Shares 31,008,915 30,806,361 18,146,838
Outstanding exercisable - Number of Shares 29,898,494    
Options and warrants outstanding, Weighted Average Exercise Price $ 1.13 $ 1.65  
Granted, Weighted Average Exercise Price 0.93 0.74  
Exercised, Weighted Average Exercise Price 0.55    
Forfeited/expired/cancelled, Weighted Average Exercise Price 1.76 1.49  
Options and warrants outstanding, Weighted Average Exercise Price 0.88 $ 1.13 $ 1.65
Outstanding exercisable, Weighted Average Exercise Price $ 0.89    
Options and warrants outstanding, Weighted Average Remaining Contractual Life 2 years 11 months 9 days 3 years 3 months 15 days 1 year 10 months 10 days
Outstanding exercisable, Weighted Average Remaining Contractual Life 2 years 10 months 28 days    
Options and warrants outstanding , Aggregate Intrinsic Value $ 5,538,335 $ 177,042 $ 140,321
Exercisable , Aggregate Intrinsic Value $ 5,334,919