1. Department
of Civil and Environmental Engineering and IIHR Hydroscience and Engineering, The University of Iowa, Iowa City, Iowa 52242, United States
2. Central
Microscopy Research Facility, The University of Iowa, Iowa City, Iowa 52242, United States
3. Department
of Earth and Environmental Sciences, The University of Iowa, Iowa City, Iowa 52242, United States
4. Department
of Civil and Environmental Engineering, Rice University, Houston, Texas 77005, United States