Quarterly report pursuant to Section 13 or 15(d)

The assumptions used in the valuation of stock options granted during the six months ended June 30, 2021 and 2020 were as follows: (Details)

v3.21.2
The assumptions used in the valuation of stock options granted during the six months ended June 30, 2021 and 2020 were as follows: (Details)
6 Months Ended
Jun. 30, 2021
Jun. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Risk-free interest rate - Minimum 0.80% 0.36%
Risk-free interest rate - Maximum 1.63% 1.25%
Expected stock price volatility - minimum 124.40% 124.11%
Expected stock price volatility - maximum 137.74% 130.00%
Expected dividend yield 0.00% 0.00%
Minimum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term of option 5 years 6 months 5 years 6 months
Maximum [Member]    
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term of option 10 years 6 years