Quarterly report pursuant to Section 13 or 15(d)

Note 6 - Registered Direct Offerings That Created Derivative Liabilities (Details Textual)

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Note 6 - Registered Direct Offerings That Created Derivative Liabilities (Details Textual) - USD ($)
 3 Months Ended
May 12, 2019
Jun. 28, 2018
Feb. 20, 2017
Dec. 31, 2021
Dec. 31, 2020
Sep. 30, 2016
Series F Warrant [Member]            
Warrants and Rights, Percent of Stock Oustanding Callable     55.00%      
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)     $ 0.75      
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)       5,591,664    
Series G Warrant [Member]            
Warrants and Rights, Percent of Stock Oustanding Callable   75.00%        
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)   $ 0.70        
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)       6,802,500    
Series H Warrant [Member]            
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) $ 0.40          
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)       8,615,384    
Series F, Series G, and Series H Warrants [Member]            
Class of Warrant or Right, Warrants Exercised (in shares)       0 0  
The 2017 SPA [Member]            
Registered Direct Offering, Maximum Amount           $ 50,000,000
Stock Issued During Period, Shares, New Issues (in shares)     10,166,664      
Shares Issued, Price Per Share (in dollars per share)     $ 0.60      
The 2018 SPA [Member]            
Stock Issued During Period, Shares, New Issues (in shares)   9,070,000        
Shares Issued, Price Per Share (in dollars per share)   $ 0.50        
The 2019 SPA [Member]            
Stock Issued During Period, Shares, New Issues (in shares) 8,615,384          
Shares Issued, Price Per Share (in dollars per share) $ 0.325