Annual report pursuant to section 13 and 15(d)

Stock Options and Warrants (Detail)

v2.4.0.8
Stock Options and Warrants (Detail) (USD $)
 12 Months Ended
May 31, 2013
May 31, 2012
May 31, 2011
Stock option and warrant activity      
Options and warrants outstanding, Number of Shares 10,327,664 7,473,576  
Granted, Number of Shares 11,166,274 3,456,088  
Exercised, Number of Shares (780,000) (527,500)  
Forfeited /expired/ cancelled, Number of Shares (2,567,000) (74,500)  
Options and warrants outstanding, Number of Shares 18,146,938 10,327,664 7,473,576
Exercisable - Number of Shares 16,253,188    
Options and warrants outstanding, Weighted Average Exercise Price $ 1.60 $ 1.34  
Granted,Weighted Average Exercise Price $ 1.61 $ 2.04  
Exercised,Weighted Average Exercise Price $ 0.26 $ 0.62  
Forfeited/expired/cancelled,Weighted Average Exercise Price $ 1.73 $ 2.49  
Options and warrants outstanding ,Weighted Average Exercise Price $ 1.65 $ 1.60 $ 1.34
Options and warrants outstanding , Aggregate Intrinsic Value $ 2,308,279 $ 10,495,913  
Exercisable ,Weighted Average Exercise Price $ 1.68    
Options and warrants outstanding , Aggregate Intrinsic Value 140,321 2,308,279 10,495,913
Options and warrants outstanding, Weighted Average Remaining Contractual Life 1 year 10 months 10 days 3 years 2 months 12 days 3 years 10 months 2 days
Exercisable , Aggregate Intrinsic Value $ 140,321    
Outstanding exercisable, Weighted Average Remaining Contractual Life 1 year 7 months 24 days