Buchananmead8598

Current methods to dynamically tune three-dimensional hydrogel mechanics require specific chemistries and substrates that make modest, slow, and often irreversible changes in their mechanical properties, exclude the use of protein-based scaffolds, or alter the hydrogel microstructure and pore size. Here, we rapidly and reversibly alter the mechanical properties of hydrogels consisting of extracellular matrix proteins and proteoglycans by adding carbonyl iron microparticles (MPs) and applying external magnetic fields. This approach drastically alters hydrogel mechanics rheology reveals that application of a 4000 Oe magnetic field to a 5 mg/mL collagen hydrogel containing 10 wt % MPs increases the storage modulus from approximately 1.5 to 30 kPa. Cell morphology experiments show that cells embedded within these hydrogels rapidly sense the magnetically induced changes in ECM stiffness. Ca2+ transients are altered within seconds of stiffening or subsequent softening, and slower but still dynamic changes occur in YAP nuclear translocation in response to time-dependent application of a magnetic field. The near instantaneous change in hydrogel mechanics provides new insight into the effect of changing extracellular stiffness on both acute and chronic changes in diverse cell types embedded in protein-based scaffolds. Due to its flexibility, this method is broadly applicable to future studies interrogating cell mechanotransduction in three-dimensional substrates.Two-dimensional transition-metal dichalcogenides (TMDs) are of particular interest as a new active material for future triboelectric nanogenerators (TENGs) owing to their excellent electrical properties, optical transparency, flexibility, ultrathin thickness, and biocompatibility. Here, we propose a new approach to engineer the surface of TMDs via conjugation with thiolated ligands having different alkane chain lengths and to develop TMD-based TENG devices that exhibit enhanced output performance for the first time. The triboelectric charging behaviors of ligand-conjugated TMDs are successfully investigated, and the electrical output performance of TMD TENGs based on TMD-to-polymer device geometries with a vertical contact-separation mode is dramatically improved, exhibiting an output voltage of 12.2 V and a power density of 138 mW/m2. Furthermore, the ligand-conjugated TMD TENG device exhibits a highly stable operation under repeated contact and separation over 10 000 cycles, as well as high chemical stability, as a result of novel defect engineering via thiolated ligand conjugation. Detailed investigation reveals that the improved performance of the ligand-conjugated TMD TENG device originates from the synergistic effect of defect engineering and the p-type doping effect of TMDs, correlated with the increased electric potential difference between triboelectric layers. These findings provide a new potential of TMDs as a promising building block for the next-generation energy harvesting system.An ultralight and high-strength SiCnw@SiC foam with highly efficient microwave absorption and heat insulation properties was successfully synthesized using the template sacrifice method and chemical vapor deposition process. The microstructure is a novel double network structure, which is formed by the coupling of the morphology-controlled SiCnw and the SiC skeleton. The introduction of SiCnw can not only provide more interface polarization and dielectric loss to the SiC foam, which greatly enhances the microwave absorption capacity of the composite foam, but also can enable it to act as an excellent radiation absorbent, which can effectively reduce the thermal conductivity of the foam, especially at high temperatures. In this study, a minimum reflection loss (RLmin) of -52.49 dB was achieved at 2.82 mm thickness with an effective absorption bandwidth of 5.6 GHz. As the length/diameter ratio of SiCnw decreases, the composite foam exhibits excellent high-temperature thermal insulation and mechanical properties. For the SiCnw@SiC foam, the thermal conductivity is only 0.304 W/mK at 1200 °C and the compressive strength reaches 1.53 MPa. This multifunctional SiCnw@SiC foam is an outstanding material, which has potential applications in microwave absorption and high-temperature heat insulation in harsh environments.Energy and mass transfer in photocatalytic systems plays a significant role in photocatalytic water splitting, but relevant research has long been ignored. Here, an interfacial photocatalytic mode for photocatalytic hydrogen production is exploited to optimize the energy and mass flows and mainly includes a heat-insulating layer, a water-channel layer, and a photothermal photocatalytic layer. In this mode, the energy flow is optimized for efficient spreading, conversion, and utilization. A low-loss path (ultrathin water film) and an efficient heat localized zone are constructed, where light energy, especially infrared-light energy, can transfer to the target functional membrane surface with low loss and the thermal energy converted from light can be localized for further use. Zileuton Meanwhile, the optimization of the mass flow is achieved by improving the desorption capacity of the products. The generated hydrogen bubbles can rapidly leave from the surface of the photocatalyst, along with the active sites being released timely. Consequently, the photocatalytic hydrogen production rate can be increased up to about 6.6 times that in a conventional photocatalytic mode. From the system design aspect, this work provides an efficient strategy to improve the performance of photocatalytic water splitting by optimizing the energy and mass flows.Improving the redox kinetics of sulfur species, while suppressing the "shuttle effects" to achieve stable cycling under high sulfur loading is an inevitable problem for lithium-sulfur (Li-S) cells to commercialization. Herein, the three-dimensional Zn, Co, and N codoped carbon nanoframe (3DZCN-C) was successfully synthesized by calcining precursor which protected by mesoporous SiO2 and was used as cathode host for the first time to improve the performance of Li-S cells. Combining the merits of strong lithium polysulfides (LiPSs) anchoring and accelerating the conversion kinetics of sulfur species, 3DZCN-C effectively inhibit the shuttling of LiPSs and achieves excellent cyclability with capacity fading rate of 0.03% per cycle over 1000 cycles. Furthermore, the Li-S pouch cell has been assembled and has been shown to operate reliably with high energy density (>300 Wh kg-1) even under a high sulfur loading of 10 mg cm-2. This work provides a simple and effective way for the promotion and commercial application of Li-S cells.