7 research outputs found

    Bioinspired Hierarchical Alumina–Graphene Oxide–Poly(vinyl alcohol) Artificial Nacre with Optimized Strength and Toughness

    No full text
    Due to hierarchical organization of micro- and nanostructures, natural nacre exhibits extraordinary strength and toughness, and thus provides a superior model for the design and fabrication of high-performance artificial composite materials. Although great progress has been made in constructing layered composites by alternately stacking hard inorganic platelets and soft polymers, the real issue is that the excellent strength of these composites was obtained at the sacrifice of toughness. In this work, inspired by the layered aragonite microplatelets/chitin nanofibers–protein structure of natural nacre, alumina microplatelets–graphene oxide nanosheets–poly­(vinyl alcohol) (Al<sub>2</sub>O<sub>3</sub>/GO–PVA) artificial nacre is successfully constructed through layer-by-layer bottom-up assembly, in which Al<sub>2</sub>O<sub>3</sub> and GO–PVA act as “bricks” and “mortar”, respectively. The artificial nacre has hierarchical “brick-and-mortar” structure and exhibits excellent strength (143 ± 13 MPa) and toughness (9.2 ± 2.7 MJ/m<sup>3</sup>), which are superior to those of natural nacre (80–135 MPa, 1.8 MJ/m<sup>3</sup>). It was demonstrated that the multiscale hierarchical structure of ultrathin GO nanosheets and submicrometer-thick Al<sub>2</sub>O<sub>3</sub> platelets can deal with the conflict between strength and toughness, thus leading to the excellent mechanical properties that cannot be obtained using only one size of platelet. We strongly believe that the work presented here provides a creative strategy for designing and developing new composites with excellent strength and toughness

    Three-Dimensional Crumpled Graphene-Based Nanosheets with Ultrahigh NO<sub>2</sub> Gas Sensibility

    No full text
    It is well-established that the structures dominate the properties. Inspired by the highly contorted and crumpled maxilloturbinate inside dog nose, herein an artificial nanostructure, i.e., 3D crumpled graphene-based nanosheets, is reported with the simple fabrication, detailed characterizations, and efficient gas-sensing applications. A facile supramolecular noncovalent assembly is introduced to modify graphene with functional molecules, followed with a lyophilization process to massively transform 2D plane graphene-based nanosheets to 3D crumpled structure. The detailed morphological characterizations reveal that the bioinspired nanosheets exhibit full consistency with maxilloturbinate. The fabricated 3D crumpled graphene-based sensors exhibit ultrahigh response (<i>R</i><sub>a</sub>/R<sub>g</sub> = 3.8) toward 10 ppm of NO<sub>2</sub>, which is mainly attributed to the specific maxilloturbinate-mimic structure. The sensors also exhibit excellent selectivity and sensing linearity, reliable repeatability, and stability. Interestingly, it is observed that only 4 mg of graphene oxide (GO) raw materials can produce more than 1000 gas sensors, which provides a new insight for developing novel 3D biomimetic materials in large-scale gas sensor production

    Tunable, Fast, Robust Hydrogel Actuators Based on Evaporation-Programmed Heterogeneous Structures

    No full text
    The ability to topographically structure and fast controllably actuate hydrogel in two and three dimensions is the key for their promising applications in soft robots, microfluidic valves, cell and drug delivery, and artificial muscles. Inspired by evaporation-induced concentration differentiation phenomenon in the production process of beancurd sheet, we introduce a facile one-step evaporation process to create laminated layer/porous layer heterogeneous structure within graphene oxide-clay-poly­(<i>N</i>-isopropylacrylamide) hydrogel in vertical direction and pattern the heterogeneous structure in lateral direction to form tunable, fast, and robust hydrogel actuators. The laminated layer/porous layer architecture is highly stable and robust without possibility of delamination. The evaporation-programmed heterogeneous structures tune thermoresponsive actuations from global bending/unbending for global heterogeneous structure to local bending/unbending and site-specific folding/unfolding for segment-patterned heterogeneous structure, then to directional bending/unbending and chiral twisting/untwisting for stripe-patterned heterogeneous structure. These actuations are instant and reversible without detectable fatigue after many cycles

    Tunable, Fast, Robust Hydrogel Actuators Based on Evaporation-Programmed Heterogeneous Structures

    No full text
    The ability to topographically structure and fast controllably actuate hydrogel in two and three dimensions is the key for their promising applications in soft robots, microfluidic valves, cell and drug delivery, and artificial muscles. Inspired by evaporation-induced concentration differentiation phenomenon in the production process of beancurd sheet, we introduce a facile one-step evaporation process to create laminated layer/porous layer heterogeneous structure within graphene oxide-clay-poly­(<i>N</i>-isopropylacrylamide) hydrogel in vertical direction and pattern the heterogeneous structure in lateral direction to form tunable, fast, and robust hydrogel actuators. The laminated layer/porous layer architecture is highly stable and robust without possibility of delamination. The evaporation-programmed heterogeneous structures tune thermoresponsive actuations from global bending/unbending for global heterogeneous structure to local bending/unbending and site-specific folding/unfolding for segment-patterned heterogeneous structure, then to directional bending/unbending and chiral twisting/untwisting for stripe-patterned heterogeneous structure. These actuations are instant and reversible without detectable fatigue after many cycles

    Table_1_Effects of tumor necrosis factor-alpha inhibitors on lipid profiles in patients with psoriasis: a systematic review and meta-analysis.docx

    No full text
    BackgroundThere is no consensus on the effect of tumor necrosis factor-alpha (TNF-alpha) inhibitors on lipid profiles in patients with psoriasis. This study aimed to investigate the effects of TNF-alpha inhibitors on lipid profiles (triglycerides, total cholesterol, low-density lipoprotein, or high-density lipoprotein) in patients with psoriasis. MethodsWe searched PubMed, Embase, and Cochrane Library databases for articles published before October 17, 2023. Four TNF-alpha inhibitors (infliximab, etanercept, adalimumab, and certolizumab) were included in our study. (PROSPERO ID: CRD42023469703).ResultsA total of twenty trials were included. Overall results revealed that TNF-alpha inhibitors elevated high-density lipoprotein levels in patients with psoriasis (WMD = 2.31; 95% CI: 0.96, 3.67; P = 0.001), which was supported by the results of sensitivity analyses excluding the effect of lipid-lowering drugs. Subgroup analyses indicated that high-density lipoprotein levels were significantly increased in the less than or equal to 3 months group (WMD = 2.88; 95% CI: 1.37, 4.4; P ConclusionOur results revealed that TNF-alpha inhibitors might temporarily increase high-density lipoprotein levels in patients with psoriasis. However, changes in triglycerides were not consistent among the different durations of treatment, with significant increases after 3 to 6 months of treatment. Future prospective trials with long-term follow-up contribute to confirming and extending our findings.Systematic Review Registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023469703.</p

    DataSheet_1_Effects of tumor necrosis factor-alpha inhibitors on lipid profiles in patients with psoriasis: a systematic review and meta-analysis.docx

    No full text
    BackgroundThere is no consensus on the effect of tumor necrosis factor-alpha (TNF-alpha) inhibitors on lipid profiles in patients with psoriasis. This study aimed to investigate the effects of TNF-alpha inhibitors on lipid profiles (triglycerides, total cholesterol, low-density lipoprotein, or high-density lipoprotein) in patients with psoriasis. MethodsWe searched PubMed, Embase, and Cochrane Library databases for articles published before October 17, 2023. Four TNF-alpha inhibitors (infliximab, etanercept, adalimumab, and certolizumab) were included in our study. (PROSPERO ID: CRD42023469703).ResultsA total of twenty trials were included. Overall results revealed that TNF-alpha inhibitors elevated high-density lipoprotein levels in patients with psoriasis (WMD = 2.31; 95% CI: 0.96, 3.67; P = 0.001), which was supported by the results of sensitivity analyses excluding the effect of lipid-lowering drugs. Subgroup analyses indicated that high-density lipoprotein levels were significantly increased in the less than or equal to 3 months group (WMD = 2.88; 95% CI: 1.37, 4.4; P ConclusionOur results revealed that TNF-alpha inhibitors might temporarily increase high-density lipoprotein levels in patients with psoriasis. However, changes in triglycerides were not consistent among the different durations of treatment, with significant increases after 3 to 6 months of treatment. Future prospective trials with long-term follow-up contribute to confirming and extending our findings.Systematic Review Registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD42023469703.</p

    Mimicking a Dog’s Nose: Scrolling Graphene Nanosheets

    No full text
    Inspired by the densely covered capillary structure inside a dog’s nose, we report an artificial nanostructure, <i>i</i>.<i>e</i>., poly­(sodium <i>p</i>-styrenesulfonate)-functionalized reduced graphene oxide nanoscrolls (PGNS), with high structural perfection and efficient gas sensing applications. A facile supramolecular assembly is introduced to functionalize graphene with the functional polymer, combined with the lyophilization technique to massively transform the planar graphene-based nanosheets to nanoscrolls. Detailed characterizations reveal that the bioinspired nanoscrolls exhibit a wide-open tubular morphology with uniform dimensions that is structurally distinct from the previously reported ones. The detailed morphologies of the graphene-based nanosheets in each scrolling stage during lyophilization are monitored by cryo-SEM. This unravels an asymmetric polymer-induced graphene scrolling mechanism including the corresponding scrolling process, which is directly presented by molecular dynamics simulations. The fabricated PGNS sensors exhibit superior gas sensing performance with reliable repeatability, excellent linear sensibility, and, especially, an ultrahigh response (<i>R</i><sub>a</sub>/<i>R</i><sub>g</sub> = 5.39, 10 ppm) toward NO<sub>2</sub>. The supramolecular assembly combined with the lyophilization technique to fabricate PGNS provides a strategy to design biomimetic materials for gas sensors and chemical trace detectors
    corecore