7 research outputs found

    Superelastic Graphene Aerogels Constructed by Structural Modulation for Piezoresistive Sensing

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    The microstructure is a critical factor in determining the macroscopic properties of aerogel materials and has a significant impact on their performance in various application scenarios. Here, drawing inspiration from the microstructure regulation of the bubble template, polyvinylpyrrolidone (PVP) was used to microscopically regulate graphene oxide nanosheets in the fabrication of the graphene aerogel (GA). Simultaneously, sodium dodecyl sulfate (SDS) foaming was employed as the bubble template to aid in the construction of PVP/SDS-GA (PSGA) with a hierarchical porous structure. Such an innovative structural blueprint inherently promotes a more even distribution of stress, thereby enhancing the compressive strength of the aerogel. The advanced architecture of PSGA enables rapid desiccation by using ambient pressure and elevated thermal methods, simplifying the fabrication process. PSGA possesses several remarkable characteristics: an ultralow density of 2.84 mg/cm3, a high electrical conductivity of 10 S/m, a superelasticity with an extreme strain of 99%, an outstanding fatigue resistance with the ability to withstand 10,000 cycles at 70% strain, and a high compressive strength of 0.66 MPa. In light of these characteristics, the piezoresistive sensor conceptualized using PSGA as a foundational substrate exhibited superior signal discernment capabilities

    Biodegradable and biocompatible alginate/gelatin/MXene composite membrane with efficient osteogenic activity and its application in guided bone regeneration

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    Guided bone regeneration (GBR) utilizes a barrier membrane to maintain the osteogenic space and promote osseointegration of the implants. Developing a novel biomaterial to meet the mechanical and biological performance requirements of GBR membrane (GBRM) remains a huge challenge. Here, the sodium alginate (SA, S)/gelatin (G)/MXene (M) composite membrane (SGM) was prepared by combining sol-gel and freeze-drying processes. The incorporation of MXene improved the mechanical properties and hydrophilicity of the SA/G (SG) membrane, and also enhanced its cell proliferation and osteogenic differentiation. More importantly, when the concentration of MXene is 0.25%W/V, the SGM composite membrane exhibited the best tensile strength (40 MPa), high swelling rate (1012%), and appropriate degradation rate (40%). Meanwhile, the biological improvements were more significant. Therefore, the appropriate amount addition of MXene has a positive and obvious effect on the improvements of the mechanical properties, biocompatibility, and osteogenic induction of the SG composite membranes. This work provides a more extendable development idea for the application of SGM composite membrane as GBRM.</p

    Fluorine Doping Strengthens the Lithium-Storage Properties of the Mn-Based Metal–Organic Framework

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    The electrochemical properties of the metal–organic framework (MOF)-based composite as electrode material can be significantly improved by means of partial destruction of the full coordination of linkers to metal ions and replacing with other small ions, which make metal centers become more accostable and consequently more effective for the lithiation/delithiation process. In this paper, F<sup>–</sup> was chosen to replace some of the benzenedicarboxylate (BDC) linkers because of its better interaction with the Li<sup>+</sup> than the oxide ion. What’s more, the formed M–F bond promotes the Li<sup>+</sup> to transfer at the active material interface and protects the surface from HF attacking. The as-synthesized F-doped Mn-MOF electrode maintains a reversible capacity of 927 mA h g<sup>–1</sup> with capacity retention of 78.5% after 100 cycles at 100 mA g<sup>–1</sup> and also exhibits a high discharge capacity of 716 mA h g<sup>–1</sup> at 300 mA g<sup>–1</sup> and 620 mA h g<sup>–1</sup> at 500 mA g<sup>–1</sup> after 500 cycles. Even at 1000 mA g<sup>–1</sup>, the electrode still maintains a high reversible capacity of 494 mA h g<sup>–1</sup> after 500 cycles as well as a Coulombic efficiency of nearly 100%, which is drastically increased compared with pure Mn-MOF material as expected

    Synthesis of a PNIPAM-Based Composite Hydrogel and Its Multipurpose Applications in Piezoresistive and Temperature Sensing

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    Herein, a poly(N-isopropylacrylamide)-based conductive composite hydrogel system coenhanced by clay and polydopamine-modified MXene was synthesized to achieve strain and temperature sensibility simultaneously. The noncovalently cross-linked network via MXene, clay, and polymer chains endowed the synthesized hydrogel with excellent mechanical properties (tensile strength at a break of 117 kPa and elongation at a break of 1723%). This hydrogel also exhibits strong adhesion and good electrical conductivity (0.13 S/m). Regarding the sensing properties, its temperature sensitivity is 2.749 °C–1, while its strain detection limit is as low as 0.05%. Based on the unique characteristics of the prepared hydrogel, the as-assembled sensor can detect stress and temperature simultaneously, exhibiting great application potential in human physiological monitoring

    Simple Synthesis of Amorphous NiWO<sub>4</sub> Nanostructure and Its Application as a Novel Cathode Material for Asymmetric Supercapacitors

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    This study reports a simple synthesis of amorphous nickel tungstate (NiWO<sub>4</sub>) nanostructure and its application as a novel cathode material for supercapacitors. The effect of reaction temperature on the electrochemical properties of the NiWO<sub>4</sub> electrode was studied, and results demonstrate that the material synthesized at 70 °C (NiW-70) has shown the highest specific capacitance of 586.2 F g<sup>–1</sup> at 0.5 A g<sup>–1</sup> in a three-electrode system. To achieve a high energy density, a NiW-70//activated carbon asymmetric supercapacitor is successfully assembled by use of NiW-70 and activated carbon as the cathode and anode, respectively, and then, its electrochemical performance is characterized by cyclic voltammetry and galvanostatic charge–discharge measurements. The results show that the assembled asymmetric supercapacitor can be cycled reversibly between 0 and 1.6 V with a high specific capacitance of 71.1 F g<sup>–1</sup> at 0.25 A g<sup>–1</sup>, which can deliver a maximum energy density of 25.3 Wh kg<sup>–1</sup> at a power density of 200 W kg<sup>–1</sup>. Furthermore, this asymmetric supercapacitor also presented an excellent, long cycle life along with 91.4% specific capacitance being retained after 5000 consecutive times of cycling

    Casein Phosphopeptide-Biofunctionalized Graphene Biocomposite for Hydroxyapatite Biomimetic Mineralization

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    Casein phosphopeptides (CPPs) with abundant phosphoserine clusters can mediate hydroxyapatite (HA) nucleation and growth. In this work, a new type of CPPs-biofuctionalized graphene composite was synthesized by amidation reaction between CPPs and carboxyalated graphene (CGO). When immersed in stimulated body fluid (1.5 × SBF) at 37 °C for different periods, the CPPs layer on the composite facilitated efficient interaction between the CGO surface and mineral ions, which promoted HA nanoparticle formation and shortened mineralization time in comparison with pristine CGO. The synthesis of the composite mimicked the natural biomineralization of bone, demonstrating that CPPs can effectively improve the bioactivity of graphene and be useful for HA formation. The presented biocomposite may have potential biomedical applications in different areas

    Method for Measuring the Three-Dimensional Morphology of Near-Wall Bubbles and Droplets Based on LED Digital Holography

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    Digital holography, recognized for its noncontact nature and high precision in three-dimensional imaging, is effectively employed to measure the morphology of bubbles and droplets. However, in terms of near-wall bubbles and droplets, such as confined bubbles in microfluidic chips, the measurement of the interface morphology of bubbles near the glass surface has not yet been resolved due to the coherent noise resulting from glass surface reflections in microfluidic chips. Accordingly, an off-axis digital holography system was devised by using Linnik interferometry. Measuring the confined bubble interface near the wall within a microfluidic chip and droplet evaporation on solid surfaces was studied. Partially coherent LED sources and reference light modulation techniques were employed in the optical setup to mitigate the coherent noise. Dual exposure and weighted least-squares unwrapping algorithms were introduced to correct phase distortions, enhancing image quality. Imaging two confined CO2 bubbles was done near the wall in silicon oil within a porous microfluidic chip, and contact angles of 4.7 and 4.5° were measured. Additionally, the measurement of the three-dimensional morphology of vertically evaporating deionized water droplets on a glass surface was done, due to which calculation of contact angles at various orientations was possible. This work offers a feasible new method for measuring the 3D interface morphology of bubbles and droplets, particularly in microfluidic visualization, addressing current measurement gaps
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