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9. Stock-Based Compensation (Details 2) - $ / shares | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016
Market value per share on grant date | $ 1.43 | $ 2.56
Equity Option [Member] |  |
Dividend-yield | 0.00% | 0.00%
Risk-free interest rate | 2.22% | 1.66%
Expected volatility | 76.96% | 77.69%
Expected life (years) | 6 years 5 months 1 day | 6 years 11 months 26 days
Market value per share on grant date | $ 1.41 | $ 2.52
Weighted average fair value per share of common stock | $ .99 | $ 1.79

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