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. 2019 Oct 10;9:14584. doi: 10.1038/s41598-019-51177-x

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© The Author(s) 2019

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

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(a) WP size distribution and average specific surface area values in a given sample. WPs (b) larger than 2 mm (Group I) (c) larger than 1.4 mm and smaller than 2 mm (Group II) (d) larger than 1 mm and smaller than 1.4 mm (Group III) (e) larger than 0.5 mm and smaller than 1 mm (Group IV) (f) larger than 0.25 mm and smaller than 0.5 mm (Group V) (g) dust (Group VI).