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Stockholders' Equity (Tables)
 6 Months Ended
Jun. 30, 2019
Equity [Abstract]  
Schedule of Estimated Values of Warrants Valuation Assumptions

The estimated values of warrants, as well as the assumptions that were used in calculating such values were based on estimates at the issuance date as follows:

 

   Placement
Agent
December 30, 2016		   Bridge
Noteholders
September 21, 2017		 
Risk-free interest rate   1.93%   1.89%
Weighted average expected term   5 years    5 years 
Expected volatility   123.07%   130.80%
Expected dividend yield   0.00%   0.00%

 

   Placement
Agent
November 17, 2017		   Placement
Agent
November 30, 2017		 
Risk-free interest rate   2.06%   2.14%
Weighted average expected term   5 years    5 years 
Expected volatility   129.87%   129.34%
Expected dividend yield   0.00%   0.00%

 

   Placement
Agent
September 20, 2018		   Placement
Agent
September 26, 2018		 
Risk-free interest rate   2.96%   2.96%
Weighted average expected term   5 years    5 years 
Expected volatility   122.52%   122.92%
Expected dividend yield   0.00%   0.00%