Browsing by Author "Yang, Yang"

Abstract Heterogeneous structures are ubiquitous in natural organisms. Native heterogeneous structures inspire many artificial structures that are playing important roles in modern society, while it is challenging to identify the relevant factors in forming these structures due to the complexity of living systems. Here, hybrid hydrogels consisting of flexible polymer networks with embedded stiff cellulose nanocrystals (CNCs) are considered an open system to simulate the generalized formation of heterogeneous core-sheath structures. As the result of the modified air drying process of hybrid hydrogels, the formation of heterogeneous core-sheath structure is found to be correlated to the relative evaporation speed. Specifically, the formation of such heterogeneity in xerogel fibers is found to be correlated with the divergence of Deborah number ( De ). During the transition of De from large to small values with accompanying morphologies, the turning point is around De  = 1. The mechanism can be considered a relative humidity-dependent glass transition behavior. These unique heterogeneous structures play a key role in tuning water permeation and water sorption capacity. Insights into these aspects can prospectively contribute to a better understanding of the native heterogeneous structures for bionics design.

Clathrin-mediated endocytosis depends on the formation of functional clathrin-coated pits that recruit cargos and mediate the uptake of those cargos into the cell. However, it remains unclear whether the cargos in the growing clathrin-coated pits are actively monitored by the coat assembly machinery. Using a cell-free reconstitution system, we report that clathrin coat formation and cargo sorting can be uncoupled, indicating that a checkpoint is required for functional cargo incorporation. We demonstrate that the ATPase Hsc70 and a dynamic exchange of clathrin during assembly are required for this checkpoint. In the absence of Hsc70 function, clathrin assembles into pits but fails to enrich cargo. Using single-molecule imaging, we further show that uncoating takes place throughout the lifetime of the growing clathrin-coated pits. Our results suggest that the dynamic exchange of clathrin, at the cost of the reduced overall assembly rates, primarily serves as a proofreading mechanism for quality control of endocytosis.

Abstract The large-scale vegetation restoration project on the Loess Plateau increased the ecosystem carbon (C) stocks and affected C budget in arid and semi-arid ecosystems. The specific details affecting the C stocks, their distribution, and dependence on land use and climate were never presented and generalized. We assessed the effects of climate factors and soil properties on ecosystem C stocks through field investigation across the Loess Plateau. The total C stocks in the four ecosystems: forestlands [0.36], shrublands [0.24], grasslands [1.18], and farmlands [1.05] was 2.84 Pg (1 Pg = 10 15  g), among which 30% were stored in topsoil (0–20 cm), 53% in above-ground biomass, and 17% in roots. The total ecosystem C density decreased according to the climate from the southeast (warm dry) to the northwest (cold moist) of the Loess Plateau. The ecosystem C density decreased with increasing temperature (from 5 to 15 °C), but increased with precipitation (from 200 to 700 mm). Variation partitioning analysis and structural equation models indicated that ecosystem C density was more explained by climate compared with soil properties. This supports the theory and empirical findings that large scale pattern of ecosystem C density is predominantly regulated by climate on the Loess Plateau. Our results highlight that grasslands are more predestined to store C compared with the other ecosystems, and the C stored in roots is substantial and should be considered when assessing C stocks and strongly contributes to soil organic matter formation. We suggest that investing in roots can be an effective strategy for meeting part of Loess Plateau C reduction goals to mitigate climate change, which is necessary for validating and parameterizing C models worldwide.

Reported herein is the novel achievement of uniform and tunable interference colors of nanocomposite films containing organized cellulose nanocrystals (CNCs) from dynamic hydrogel precursors. Homogeneous and amendable interference colors with broad range are obtained either by stacking the nanocomposite films to adjust the amount of CNCs in the propagation pathway of light or by regulating the rotation angles between the individual films to alter the relative organization of CNCs within the system. Moreover, the precise and controllable patterned CNC composite films with multicolors in one film are facilely fabricated for the first time from the patterned hydrogel precursors. Based on this stacking/rotation‐method, these patterned nanocomposite films with tunable interference colors can be further applied as fundamental elements for optical encryption by establishing a ternary‐coded decimal system with encoded decimal numerals, paving the way for the development of photonic functional materials based on CNCs.