6. Property and Equipment

Major classes of property and equipment consisted of the following as of the dates presented below:

During the three and six month periods ended June 30, 2026, property and equipment depreciation expense was approximately $78,100 and $164,700, respectively. During the three and six month periods ended June 30, 2025 property and equipment depreciation expense was approximately $91,400 and $177,300, respectively.

During the three month period ended June 30, 2026, the Company did not dispose of any property and equipment. During the six month period ended June 30, 2026, the Company sold fully depreciated property and equipment with historical cost and accumulated depreciation of $105,200 and received proceeds of $49,043.

During the three month period ended June 30, 2025, the Company disposed of fully depreciated property and equipment with historical cost of $118,800 and accumulated depreciation of $110,600 and recognized a loss on disposal of property and equipment of $8,200. During the six month period ended June 30, 2025, the Company disposed of property and equipment with historical cost of $775,000 and accumulated depreciation of $766,800 and recognized a loss on disposal of property and equipment of $8,200.

There were no changes in the estimated useful lives used to depreciate property and equipment during the three and six month periods ended June 30, 2026 and 2025.