Annual report pursuant to Section 13 and 15(d)

Stock Options and Warrants - Additional Information (Detail)

v3.2.0.727
Stock Options and Warrants - Additional Information (Detail)
 2 Months Ended 12 Months Ended
May. 31, 2013
$ / shares
shares
May. 31, 2015
USD ($)
Tranche
$ / shares
shares
May. 31, 2014
USD ($)
$ / shares
Feb. 28, 2015
shares
Feb. 06, 2015
$ / shares
shares
Sep. 26, 2014
$ / shares
shares
Oct. 23, 2013
$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares $ 0.75 $ 0.50          
Term of warrants 5 years 5 years          
Interest expense associated with conversion and exercise inducement | $   $ 1,526,254 $ 193,160        
Cash proceeds from warrant exercises | $   1,141,435 50,000        
Direct costs associated with the convertible notes | $   $ 708,000 $ 120,000        
Minimum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares   $ 0.75          
Maximum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares   2.00          
Alpha Venture Capital Partners, L.P.              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares   $ 0.50     $ 0.50 $ 0.50  
Term of warrants   5 years          
Alpha Venture Capital Partners, L.P. | Detachable common stock warrants with a two-year term              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   250,000       250,000  
Alpha Venture Capital Partners, L.P. | Detachable common stock warrants, with terms of two or three years              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   75,000     75,000    
Investor              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise 8,527,984 9,451,056          
Warrant exercise price | $ / shares     $ 0.50        
Investor | Minimum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares $ 0.75 $ 0.50          
Investor | Maximum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares $ 2.00 $ 2.00          
Third Party Consulting Firm and Scientific Advisor              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Exercisable warrants, vesting percentage   50.00%          
Exercisable warrants, expire period   5 years          
Shares of Common Stock issued upon exercise   150,000          
Warrant exercise price | $ / shares   $ 0.83          
Warrants, termination date   Dec. 08, 2019          
Number of tranches for warrant vesting | Tranche   3          
Warrants vested in each trance   50,000          
Third Party Consulting Firm and Scientific Advisor | Tranche 1              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrants, exercisable date   Mar. 31, 2015          
Third Party Consulting Firm and Scientific Advisor | Tranche 2              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrants, exercisable date   Sep. 30, 2015          
Third Party Consulting Firm and Scientific Advisor | Tranche 3              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrants, exercisable date   Mar. 31, 2016          
Scientific advisor              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   100,000          
Warrant exercise price | $ / shares   $ 1.15          
Warrants, termination date   Dec. 31, 2019          
Scientific advisor | Tranche 1              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrants, exercisable date   Apr. 30, 2015          
Warrants vested and become exercisable   33,334          
Scientific advisor | Tranche 2              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrants, exercisable date   Aug. 31, 2015          
Warrants vested and become exercisable   33,333          
Scientific advisor | Tranche 3              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrants, exercisable date   Dec. 31, 2015          
Warrants vested and become exercisable   33,333          
Private Equity Offering              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares   $ 0.75         $ 0.75
Convertible Debt              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares   $ 0.75          
Term of warrants   5 years          
Face amount of notes | $   $ 7,531,050          
Convertible Debt | Investor              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   1,061,586          
Face amount of notes | $   $ 4,000,000          
Convertible Debt | Private Equity Offering              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   530,802          
Warrant exercise price | $ / shares   $ 0.75          
Term of warrants   5 years          
Direct costs associated with the convertible notes | $   $ 285,000          
Convertible Note One              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   1,938,974          
Warrant exercise price | $ / shares   $ 2.00          
Interest expense associated with conversion and exercise inducement | $   $ 555,000          
Cash proceeds from warrant exercises | $   $ 1,066,435          
Convertible Note One | Reduction in Conversion Price              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares   $ 0.55          
Convertible Note One | Additional              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Cash proceeds from warrant exercises | $   $ 75,000          
Stock warrants exercised | $   $ 100,000          
Warrants exercise price per share | $ / shares   $ 0.75          
2012 Equity Incentive Plan              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   6,310,677          
Warrant exercise price | $ / shares   $ 1.00          
Warrants, exercisable date   Oct. 31, 2015          
Interest expense associated with conversion and exercise inducement | $   $ 970,000          
Compensation expense related to stock options and warrants | $   631,000 $ 928,400        
Grant date fair value of options | $   886,000 $ 2,274,000        
Unrecognized compensation costs | $   $ 527,000          
Weighted average period over which unrecognized compensation costs is expected to be recognized   1 year 1 month 17 days          
2012 Equity Incentive Plan | Exercisable through December 2015              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   186,667          
2012 Equity Incentive Plan | Exercisable until January 15, 2016              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   160,000          
2012 Equity Incentive Plan | Consultant Two              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   150,000          
Warrant exercise price | $ / shares   $ 1.05          
2012 Equity Incentive Plan | Third Party Consulting Firm and Scientific Advisor              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares of Common Stock issued upon exercise   150,000          
2012 Equity Incentive Plan | Third Party Consulting Firm and Scientific Advisor | Consultant One              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Warrant exercise price | $ / shares   $ 1.15          
2012 Equity Incentive Plan | Stock Options              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares available for future stock-based grants   2,754,930          
2012 Equity Incentive Plan | Stock Options | Before Amendment              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares available for future issuance       3,000,000      
2012 Equity Incentive Plan | Stock Options | After amendment              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Shares available for future issuance       5,000,000      
2012 Equity Incentive Plan | Stock Options | Directors and Employee              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock options granted, shares   483,973          
Stock options grant date fair value | $ / shares   $ 0.43          
2012 Equity Incentive Plan | Stock Options | Directors and Employee | Minimum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock options granted, exercise price | $ / shares   0.66          
2012 Equity Incentive Plan | Stock Options | Directors and Employee | Maximum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock options granted, exercise price | $ / shares   $ 0.81          
2012 Equity Incentive Plan | Stock Options | Directors              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Exercisable warrants, expire period   5 years          
Stock options grant date fair value | $ / shares   $ 0.35          
2012 Equity Incentive Plan | Stock Options | Employees              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock options, number of shares vested   50,000          
Stock options, vesting period   3 years          
Exercisable warrants, expire period   5 years          
2012 Equity Incentive Plan | Stock Options | Vesting Schedule One | Directors              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock options, number of shares vested   333,973          
Stock options, vesting period   1 year          
Exercisable warrants, vesting percentage   25.00%          
2012 Equity Incentive Plan | Stock Options | Vesting Schedule Two | Directors              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Stock options, number of shares vested   100,000          
Stock options, vesting period   2 years          
Exercisable warrants, vesting percentage   50.00%