Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] |
| | 2015 | | 2014 | | | | | | | | | | Tax provision (benefit) | | | | | | | | Current | | | | | | | | Federal | | $ | | | $ | | | State | | | | | | | | Total current | | | | | | | | | | | | | | | | Deferred | | | | | | | | Federal | | | (3,105,641) | | | (3,868,524) | | State | | | 42,562 | | | 810,914 | | Total deferred | | | (3,063,079) | | | (3,057,610) | | | | | | | | | | Change in valuation allowance | | | 3,063,079 | | | 3,057,610 | | Total | | $ | | | $ | | |
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Schedule of Deferred Tax Assets and Liabilities [Table Text Block] |
Deferred tax assets consisted of the following at December 31:
| | 2015 | | 2014 | | | | | | | | | | Deferred tax assets | | | | | | | | Federal net operating loss | | $ | 32,565,906 | | $ | 29,246,965 | | Federal research and development tax credit carryforwards | | | 2,858,628 | | | 2,689,775 | | State net operating loss | | | 1,812,722 | | | 1,813,954 | | State research and development tax credit carryforwards | | | 806,568 | | | 753,818 | | Capitalized research and development expenses | | | 9,883,932 | | | 10,609,942 | | Stock-based compensation expense | | | 1,993,664 | | | 1,758,909 | | Charitable contributions carryforwards | | | 340 | | | | | Intangible assets | | | 253,971 | | | 313,412 | | Charitable contribution carryforwards | | | | | | | | Accrued liabilities | | | 35,332 | | | 35,392 | | Total deferred tax assets | | | 50,211,063 | | | 47,222,167 | | | | | | | | | | Deferred tax liabilities | | | | | | | | Depreciable assets | | | (171,602) | | | (245,785) | | Total deferred tax liabilities | | | (171,602) | | | (245,785) | | | | | | | | | | Net deferred tax assets | | | 50,039,461 | | | 46,976,382 | | Less valuation allowance | | | (50,039,461) | | | (46,976,382) | | Total deferred tax assets | | $ | | | $ | | |
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