1. State Key Laboratory of Coal Resources and Safe Mining, China University of Mining and Technology (Beijing), Beijing, China
2. College of Geoscience and Surveying Engineering, China University of Mining and Technology (Beijing), Beijing, China
3. School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, Australia
4. Center for Applied Energy Research, University of Kentucky, Lexington, KY, USA
5. Geosciences Department, University of Texas at Dallas, Richardson, TX, USA