Superflexible and Lead-Free Piezoelectric Nanogenerator as a Highly Sensitive Self-Powered Sensor for Human Motion Monitoring

For traditional piezoelectric sensors based on poled ceramics,a low curie tem-perature(T_(c))is a fatal flaw due to the depolarization phenomenon.However,in this study,we find the low T_(c) would be a benefit for flex-ible piezoelectric sensors because small alterations of force trig-ger large changes in polarization.BaTi_(0.88)Sn_(0.12)O_(3)(BTS)with high piezoelectric coefficient and low T_(c) close to human body temperature is taken as an example for materials of this kind.Continuous piezo-electric BTS films were deposited on the flexible glass fiber fabrics(GFF),self-powered sensors based on the ultra-thin,superflexible,and polarization-free BTS-GFF/PVDF composite piezoelectric films are used for human motion sensing.In the low force region(1-9 N),the sensors have the outstanding performance with voltage sensitivity of 1.23 V N^(−1) and current sensitivity of 41.0 nA N^(−1).The BTS-GFF/PVDF sensors can be used to detect the tiny forces of falling water drops,finger joint motion,tiny surface deformation,and fatigue driving with high sensitivity.This work provides a new paradigm for the preparation of superflexible,highly sensitive and wearable self-powered piezoelectric sensors,and this kind of sensors will have a broad application prospect in the fields of medical rehabilitation,human motion monitoring,and intelligent robot.

Gut Microbiota-Controlled Tryptophan Metabolism Improves D-Gal/LPS-Induced Acute Liver Failure in C57BL/6 Mice

Acute liver failure(ALF)has an abrupt onset with a frequently fatal outcome.Previous studies have found that oral antibiotics prevent drug-induced liver injury in animal experiments,indicating that the gut microbiota plays a critical role in the pathophysiological process.However,the underlying mechanism has not been fully understood.This study explored the comprehensive role of the gut microbiota in ALF using multi-omics.A cocktail of broad-spectrum antibiotics(Abx)pretreatment by gavage for four weeks improved the survival of D-(+)-galactosamine hydrochloride(D-Gal)/lipopolysaccharide(LPS)-induced ALF in C57BL/6 mice.RNA sequencing showed that inflammatory responses were inhibited and metabolic pathways were upregulated in the liver of Abx-treated ALF mice.The 16S rRNA gene sequencing revealed that Abx reshaped the composition and function of the gut microbiota,with an increased proportion of tryptophan(Trp)metabolism.In addition,global metabolic profiling by ultraperformance liquid chromatography–mass spectrometry(UPLC–MS)indicated that the gut microbiota post-Abx intervention reduced Trp excretion,liberated more Trp to the host,and enhanced the kynurenine(Kyn)pathway with increased production of Kyn.As an endogenous aryl hydrocarbon receptor(AhR)ligand,Kyn has anti-inflammatory and immunosuppressive effects.Furthermore,AhR-targeted treatments affected the outcome of ALF mice with or without Abx pretreatment,indicating that AhR directly regulated susceptibility to ALF,at least in part.This study demonstrates that the gut microbiota-dependent control of the Trp metabolism could regulate host susceptibility to ALF by modulating the activity of AhR,and thus provides a promising target for better management of ALF.