(6) Property, plant and equipment, net

As of September 30, 2024 and December 31, 2023, property, plant and equipment consisted of the following:

As of September 30, 2024 and December 31, 2023, land use rights represented twenty three parcels of state-owned lands located in Xushui District and Wei County of Hebei Province in China, with lease terms of 50 years expiring in 2061 and 2068, respectively.

As of September 30, 2024 and December 31, 2023, certain property, plant and equipment of Dongfang Paper with net values of $nil, have been pledged pursuant to a long-term loan from credit union of Dongfang Paper. Land use right of Tengsheng Paper with net value of $4,875,045 and $4,910,034, respectively, as of September 30, 2024 and December 31, 2023 was pledged for a long-term loan from credit union of Baoding Shengde. In addition, land use right of Tengsheng Paper with net value of $3,744,874 and $3,781,366, respectively, as of September 30, 2024 and December 31, 2023 was pledged for another long-term loan from credit union of Baoding Shengde. Certain property, plant and equipment of Dongfang Paper with net values of $251,593 was pledged for a short-term loan from Bank of Cangzhou. See “Short-term bank loans” under Note (8), Loans Payable, for details of the transaction and asset collaterals.

Depreciation and amortization of property, plant and equipment was $3,483,298 and $3,423,231 for the three months ended September 30, 2024 and 2023, respectively. Depreciation and amortization of property, plant and equipment was $10,346,181 and $10,573,288 for the nine months ended September 30, 2024 and 2023, respectively.