| Years Ended December 31, | ||||||||
| 201 7 | 201 6 | |||||||
| Statutory federal rate | 21.0 | % | 34.0 | % | ||||
| State income taxes net of federal income tax benefit | 0.0 | % | 0.0 | % | ||||
| Permanent differences for tax purposes | -0.3 | % | -0.1 | % | ||||
| Federal rate reduction | -120.7 | % | 0.0 | % | ||||
| Change in valuation allowance | 100.0 | % | -40.0 | % | ||||
| Effective income tax rate: | 0.0 | % | -6.1 | % | ||||
| December 31, | ||||||||
| 201 7 | 201 6 | |||||||
| Deferred tax assets: | ||||||||
| Net operating loss carryovers | $ | 4,377,202 | $ | 6,017,984 | ||||
| Stock-based compensation | 1,886,250 | 2,177,926 | ||||||
| Other temporary differences | 1,058,115 | 1,080,361 | ||||||
| Total deferred tax assets | 7,321,567 | 9,276,271 | ||||||
| Valuation allowance | (7,321,567 | ) | (9,276,271 | ) | ||||
| Net deferred tax asset | $ | - | $ | - | ||||