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Stockholders' Equity (Tables)
3 Months Ended
Mar. 31, 2022
Stockholders' Equity  
Schedule of common stock warrants outstanding

    

Common Stock 

Warrants

Outstanding, December 31, 2020

 

758,939

Issued

 

31,000

Expired

 

(42,556)

Outstanding, March 31, 2021

 

747,383

Schedule of stock option valuation assumptions

The following table summarizes weighted-average assumptions used in our calculations of fair value for the three months ended March 31, 2022 and 2021:

    

2022

2021

Dividend yield

 

%  

%

Expected volatility

 

103.82

%  

101.43

%

Risk-free interest rate

 

1.95

%  

0.43

%

Expected lives (years)

 

6.1

years

5.5

years

Schedule of stock option activity

    

    

Weighted

 

 

Weighted

Average

 

Aggregate

 

Average

Exercise

 

Intrinsic

 

Remaining

Shares

Price

 

Value

 

Contractual Life

Stock options outstanding at December 31, 2021

2,954,315

$

7.62

$

101,306

Granted

 

78,250

$

2.86

 

Expired

 

(542)

$

60.90

 

Forfeited

 

(28,109)

$

4.91

 

Stock options outstanding at March 31, 2022

 

3,003,914

$

7.52

$

116,956

8.7

Years

Stock options exercisable at March 31, 2022

1,356,824

$

11.10

$

62,432

8.0

Years

Schedule of restricted stock activity

Weighted

Average

Shares

Fair Value

Restricted stock at December 31, 2021

370,170

$

4.71

Granted

Vested

(323,311)

$

4.92

Cancelled

Restricted stock at March 31, 2022

46,859

$

3.28