Annual report pursuant to Section 13 and 15(d)

Stock Options and Warrants (Detail)

v3.5.0.2
Stock Options and Warrants (Detail) - USD ($)
 12 Months Ended
May 31, 2016
May 31, 2015
May 31, 2014
Stock option and warrant activity      
Options and warrants outstanding, Number of Shares 31,008,915 30,806,361  
Granted, Number of Shares 33,838,536 9,262,038  
Exercised, Number of Shares (1,050,301) (2,038,974)  
Forfeited/expired/cancelled, Number of Shares (490,000) (7,020,510)  
Options and warrants outstanding, Number of Shares 63,307,150 31,008,915 30,806,361
Outstanding exercisable, Number of Shares 60,648,362    
Options and warrants outstanding, Weighted Average Exercise Price $ 0.88 $ 1.13  
Granted, Weighted Average Exercise Price 0.80 0.93  
Exercised, Weighted Average Exercise Price 0.70 0.55  
Forfeited/expired/cancelled, Weighted Average Exercise Price 2.01 1.76  
Options and warrants outstanding, Weighted Average Exercise Price 0.83 $ 0.88 $ 1.13
Outstanding exercisable, Weighted Average Exercise Price $ 0.83    
Options and warrants outstanding, Weighted Average Remaining Contractual Life 3 years 2 months 12 days 2 years 11 months 9 days 3 years 3 months 15 days
Outstanding exercisable, Weighted Average Remaining Contractual Life 3 years 5 months 1 day    
Options and warrants outstanding, Aggregate Intrinsic Value $ 9,863,492 $ 5,538,335 $ 177,042
Outstanding exercisable, Aggregate Intrinsic Value $ 9,795,753