Quarterly report pursuant to sections 13 or 15(d)

Stock Options and Warrants (Detail)

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Stock Options and Warrants (Detail) (USD $)
 9 Months Ended
Feb. 28, 2013
May 31, 2012
Stock option and warrant activity    
Options and warrants outstanding, Number of Shares 10,327,664  
Granted, Number of Shares 9,615,633  
Exercised, Number of Shares (755,000)  
Forfeited /expired/ cancelled, Number of Shares (1,150,000)  
Options and warrants outstanding, Number of Shares 18,038,297 10,327,664
Outstanding exercisable, Number of Shares 16,833,232  
Options and warrants outstanding, Weighted Average Exercise Price $ 1.60  
Granted, Weighted Average Exercise Price $ 1.70  
Exercised, Weighted Average Exercise Price $ 0.25  
Forfeited /expired/ cancelled, Weighted Average Exercise Price $ 2.00  
Options and warrants outstanding, Weighted Average Exercise Price $ 1.68 $ 1.60
Outstanding exercisable, Weighted Average Exercise Price $ 1.67  
Options and warrants outstanding, Weighted Average Remaining Contractual Life 2 years 7 days 3 years 2 months 12 days
Outstanding exercisable, Weighted Average Remaining Contractual Life 1 year 10 months 21 days  
Options and warrants outstanding, Aggregate Intrinsic Value $ 2,308,279  
Options and warrants outstanding, Aggregate Intrinsic Value 1,793,958 2,308,279
Outstanding exercisable, Aggregate Intrinsic Value $ 1,793,958