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| Trung Vo, Thanh; Nezamabadi, Saeid; Mutabaruka, Patrick; Delenne, Jean-yves; Radjai, Farhang. |
| Granular flows are omnipresent in nature and industrial processes, but their rheological properties such as apparent friction and packing fraction are still elusive when inertial, cohesive and viscous interactions occur between particles in addition to frictional and elastic forces. Here we report on extensive particle dynamics simulations of such complex flows for a model granular system composed of perfectly rigid particles. We show that, when the apparent friction and packing fraction are normalized by their cohesion-dependent quasistatic values, they are governed by a single dimensionless number that, by virtue of stress additivity, accounts for all interactions. We also find that this dimensionless parameter, as a generalized inertial number,... |
| Tipo: Text |
Palavras-chave: Civil engineering; Colloids; Physics; Process chemistry; Rheology. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00685/79680/82460.pdf |
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| Escoube, Raphaelle; Rouxel, Olivier; Pokrovsky, Oleg S.; Schroth, Andrew; Holmes, Robert Max; Donard, Olivier F. X.. |
| The input of iron to the Arctic Ocean plays a critical role in the productivity of aquatic ecosystems and is potentially impacted by climate change. We examine Fe isotope systematics of dissolved and colloidal Fe from several Arctic and sub-Arctic rivers in northern Eurasia and Alaska. We demonstrate that the Fe isotopic (δ56Fe) composition of large rivers, such as the Ob’ and Lena, has a restricted range of δ56Fe values ca.–0.11 ± 0.13‰, with minimal seasonal variability, in stark contrast to smaller organic-rich rivers with an overall δ56Fe range from–1.7 to + 1.6‰. The preferential enrichment with heavy Fe isotopes observed in low molecular weight colloidal fraction and during the high-flow period is consistent with the role of organic complexation of... |
| Tipo: Text |
Palavras-chave: Iron isotope; Colloids; River; Weathering; Arctic; Iron speciation. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00273/38402/36865.pdf |
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| Melo,Thadeu Rodrigues de; Machado,Wesley; Tavares Filho,João. |
| ABSTRACT: Few approaches have been developed to measure the isolated effect of exchangeable cations on clay dispersion in soils. In this study, the charge sparsity (CS) index was proposed using the ratio between the cations hydrated ionic radius and valence. The index capacity to measure cation effects on clay dispersion in soils was also evaluated. Three Ferralsols, sampled at different sites in Paraná State, Brazil, were homoionized with Ca2+, Mg2+, K+, or Na+ prior to evaluation of the clay dispersion degree. Published independent data for two soils and clays were also used. We tested the capacity of CS and II, the latter proposed by Marchuck and Rengasamy (2011), to predict clay dispersion in soils. The CS predicted the dispersion degree more... |
| Tipo: Info:eu-repo/semantics/article |
Palavras-chave: Colloids; Electrical double layer; Aggregation; Flocculation; Zeta potential. |
| Ano: 2020 |
URL: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0103-90162020000101400 |
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