Piezoelectric nanogenerators (PENGs) with good flexibility and high outputs have promising applications in harvesting mechanical energy and powering electronics. In this study, a synthesis of hierarchical BaTiO3 flowers (BTFs) and their filling into the polydimethylsiloxane (PDMS) matrix to obtain composites with excellent energy harvesting properties is reported. The BTF‐based PENG possesses a voltage of 260 V, a current of 50 µA, and a power of 1728 µW under a compression of 50 N at 3.5 Hz, which output power is two orders higher than that of polymer composites filled with BT nanoparticles. Simulation indicates that the high local stress at petals of BTFs is the main reason for the enhanced performances. The PENG shows good durability under 5000 cycles and lights up 58 commercial light emitting diodes and a display. The PENG generates 30–100 V in harvesting human motions of hand slapping and foot stepping and ≈50 V in harvesting the sport kinetic energy of basketball bouncing. This research presents a BTF‐based PENG with significantly enhanced energy harvesting performances for applications in micro/nanoenergy systems.
In this study, a flower-like TiO2 filled polymethyl methacrylate (PMMA) composite is presented as a positive tribo-material to produce an excellent-performance triboelectric nanogenerator (TENG).
To investigate the effects of two Enterococcus faecalis root canal isolated strains (CA1 and CA2) and of the OG1RF strain on apoptosis, pyroptosis, and necroptosis in macrophages. The virulence factors of E. faecalis CA1 and CA2 pathogenic strains were annotated in the Virulence Factors Database (VFDB). E. faecalis CA1, CA2, and OG1RF strains were used to infect RAW264.7 macrophages (MOI, 100:1). We assessed the viability of intracellular and extracellular bacteria and of macrophages at 2, 6, and 12 h post-infection. We used a live cell imaging analysis system to obtain a dynamic curve of cell death after infection by each of the three E. faecalis strains. At 6 and 12 h post-infection, we quantified the mRNA expression levels of PANoptosis-related genes and proteins by RT-qPCR and western blot, respectively. We identified ultrastructural changes in RAW264.7 cells infected with E. faecalis OG1RF using transmission electron microscopy. We found 145 and 160 virulence factors in the CA1 and CA2 strains, respectively. The extracellular CA1 strains grew faster than the CA2 and OG1RF strains, and the amount of intracellular viable bacteria in the OG1RF group was highest at 6 and 12 h post-infection. The macrophages in the CA1 infection group were the first to reach the maximum PI-positivity in the cell death time point curve. We found the expressions of mRNA expression of caspase-1, GSDMD, caspase-3, MLKL, RIPK3, NLRP3, IL-1β and IL-18 and of proteins cleaved caspase-1, GSDMD, cleaved caspase-3 and pMIKL in the macrophages of the three infection groups to be upregulated (P<0.05). We detected ultrastructural changes of apoptosis, pyroptosis, and necroptosis in macrophages infected with E. faecalis. The three E. faecalis strains induced varying degrees of apoptosis, pyroptosis, and necroptosis that were probably associated with PANoptosis in macrophages. The E. faecalis CA1 strain exhibited faster growth and a higher real-time MOI, and it induced higher expression levels of some PANoptosis-related genes and proteins in the infected macrophages than the other strains tested.
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