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10. Stock-Based Compensation (Details 2) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Dividend-yield	0.00%	0.00%
Risk-free interest rate	2.13%	2.25%
Expected volatility	103.00%	92.20%
Expected life (years)	2 years	2 years
Market value per share on grant date	$ .73	$ 1.05
Equity Option [Member]
Dividend-yield	0.00%	0.00%
Risk-free interest rate	2.38%	2.71%
Expected volatility	88.54%	82.99%
Expected life (years)	6 years 6 months 18 days	6 years 5 months 23 days
Market value per share on grant date	$ .78	$ 1.07
Weighted average fair value per share of common stock	$ .59	$ 0.79

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The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period.

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The risk-free interest rate assumption that is used in valuing an option on its own shares.

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Expected term of award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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