Significance Recent experimental studies report correlations between carbon nanotube toxicity and tube length and stiffness. Very little is known, however, about the actual behavior of these fibrous nanomaterials inside living cells following uptake, and the fundamental mechanistic link between stiffness and toxicity is unclear. Here we reveal a nanomechanical mechanism by which sufficiently long and stiff carbon nanotubes damage lysosomes, a class of membrane-enclosed organelles found inside cells that are responsible for breaking down diverse biomolecules and debris. The precise material parameters needed to activate this unique mechanical toxicity pathway are identified through coupled theoretical modeling, molecular dynamics simulations, and experimental studies, leading to a predictive pathogenicity classification diagram that distinguishes toxic from biocompatible nanomaterials based on their geometry and stiffness.
Abstract Anthropogenic impacts and climate change modify instream flow, altering ecosystem services and impacting on aquatic ecosystems. Alpine rivers and streams on the Qinghai‐Tibet Plateau (QTP) are especially vulnerable to disturbance owing to limited taxonomic complexity. The effects of flow have been studied using specific taxa, yet the flow‐biota relationships of assemblages are poorly understood. A multi‐metric habitat suitability model (MM‐HSM) was developed using integrated measures of entire macroinvertebrate assemblages to substitute for habitat suitability indices derived from individual taxa. The MM‐HSM was trained using macroinvertebrates data from three alpine rivers on the QTP, including the Yarlung Tsangpo, the Nujiang, and the Bai rivers, and then validated using data from a forth alpine river (the Lanmucuo). The model produced predictions using the training data set ( R 2 = 0.587) and the validation data set ( R 2 = 0.489). By coupling the MM‐HSM with hydrodynamic simulations, the relationship between weighted usable area and flow (0.11–1.99 m 3 s −1 ) for macroinvertebrate assemblages was established, whereby a unimodal response pattern was observed for the Lanmucuo River. This contrast with monotonically positive or negative relationships observed for individual indicator taxa further supported our hypothesis that the response pattern of entire macroinvertebrate assemblages to flow would differ from responses of individual indicator taxa. The MM‐HSM provides a novel framework to quantify flow‐biota relationships, which is a useful approach for integrated river management.
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