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The development of miniature devices has generated a large demand for dielectric polymers with high energy storage density, especially at high temperatures. First, poly(methyl methacrylate) (PMMA)-coated nanodiamond (ND) particles were incorporated into a polyimide (PI) substrate to fabricate ND-g-PMMA/PI (NPP) composites. We found for the first time that with a very low content (0.4 vol.%) of ND particles, NPP-0.4 composite material gave the dielectric constant of 4.4, which is 37.5% higher than that of the PI film. The maximum energy density of the NPP-0.4 composite film achieves 9.4 J cm−3at room temperature, which is 54% higher than that of the PI film. Furthermore, we found that the NPP-0.2 composite reaches the highest energy density and discharge efficiency of 5.77 J cm−3and 72.3% at 150°C, which are 104% and 51.3% higher than those of the PI film at 150°C. This result shows a much higher energy density than most previously published results for high-temperature polymer capacitors. This phenomenon can be explained by the simulation results using COMSOL in which the interface polarization of ND/PI composites reached their maximum value with ultralow ND contents (0.4 vol.%). This research shows great promise for polymer capacitors with relatively high energy density at high temperatures.

The Omicron BA.2 variant has become a dominant infective strain worldwide. Receptor binding studies show that the Omicron BA.2 spike trimer exhibits 11-fold and 2-fold higher potency in binding to human ACE2 than the spike trimer from the wildtype (WT) and Omicron BA.1 strains. The structure of the BA.2 spike trimer complexed with human ACE2 reveals that all three receptor-binding domains (RBDs) in the spike trimer are in open conformation, ready for ACE2 binding, thus providing a basis for the increased infectivity of the BA.2 strain. JMB2002, a therapeutic antibody that was shown to efficiently inhibit Omicron BA.1, also shows potent neutralization activities against Omicron BA.2. In addition, both BA.1 and BA.2 spike trimers are able to bind to mouse ACE2 with high potency. In contrast, the WT spike trimer binds well to cat ACE2 but not to mouse ACE2. The structures of both BA.1 and BA.2 spike trimer bound to mouse ACE2 reveal the basis for their high affinity interactions. Together, these results suggest a possible evolution pathway for Omicron BA.1 and BA.2 variants via a human-cat-mouse-human circle, which could have important implications in establishing an effective strategy for combating SARS-CoV-2 viral infections.

Ferroelectric memories show great potential in applications of portable electronics due to low power consumption, high reliability and fast response speed. Therefore, non-destructive readout of ferroelectric memories using the ferroelectric photovoltaic effect attracted tremendous research attention. In this investigation, flexoelectric-enhanced photovoltaic effect (FPV effect) were systematically investigated in curved 3D-printed BaTiO3/PVDF composite films. In the bending process, a strain gradient field was formed between the BaTiO3(BTO) particles, which led to a relatively large flexoelectric effect. Compared with that of pristine PVDF, the flexoelectric coefficient of BTO/PVDF-15 (15% BTO) was increased 3.7-fold to 2.65 × 10−9C/m. Furthermore, we found that the photovoltaic current Ipvof the BTO/PVDF-15 (15% BTO) composite film increased by 3.4 times compared with the pristine PVDF film at the same curvature. This is mainly attributed to the FPV effect. In addition, “polarization channels” were found for the first time inside nanocomposite materials using the flexoelectricity effect through 2D phase-field simulations, and the channels can be artificially controlled by simply bending the film. Most importantly, the BTO/PVDF-based composite film was designed as flexible ferroelectric memories. We demonstrated for the first time that the intensity difference of the signal for 0 and 1 of the BTO/PVDF-based memories were more than 10 times, which can be read directly using a laser. This investigation shows great promise that flexoelectricity in piezoelectric polymer nanocomposite can greatly benefit the nondestructive readout of ferroelectric memory devices.

A Ti/α-PbO2/β-PbO2electrode with high stability was prepared and examined toward the electrochemical degradation of 2-chlorophenol. Scanning electron microscopy analysis revealed that Ti/α-PbO2/β-PbO2had a cauliflower morphology comprising small β-PbO2crystals. The 2-chlorophenol removal rate using the Ti/α-PbO2/β-PbO2electrode was 100% after 180 min of electrolysis under optimal conditions, which were selected based on the orthogonal test method, i.e., initial concentration of 2-cholorophenol = 50 mg/L, concentration of Na2SO4= 0.1 mol/L, temperature = 35 °C, and anode current density = 20 mA/cm2. Kinetic analyses demonstrated that the electrochemical oxidation of 2-chlorophenol on the Ti/α-PbO2/β-PbO2electrode followed pseudo-first order kinetics.

In this investigation, we report the flexoelectricity-enhanced photovoltaic (FPV) effect in a flexible Pb(Zr0.52Ti0.48)O3nanowire (PZT NW) array/PDMS (polydimethylsiloxane) nanocomposite. The simulation result of density functional theory (DFT) indicated that the FPV effect in PZT NWs can be greatly affected by the interactions of the strain gradients with the internal field generated by self-polarization. We found that when the nanocomposite film was curved down, the photovoltaic current of the aligned PZT-NW/PDMS composite increased by 84.6-fold and 27.6-fold compared with the PZT-nanoparticles/PDMS and randomly aligned PZT-NW/PDMS nanocomposites at the same curvature, respectively. This is mainly ascribed to the increased flexoelectricity in the aligned PZT-NW/PDMS nanocomposite. This study will contribute to a full understanding of the influence of nanoparticle shape on the flexophotovoltaic effect of nanocomposites. It will have potential use in nanocomposites for the study of the FPV effect and associated applications.

The fish pathogen Vibrio alginolyticuscontains two unique flagellar systems. The LuxS quorum sensing system is reported to regulate the expression of virulence factors in a wide variety of pathogenic bacteria. Our previous work demonstrated that inactive luxSled to decreased virulence in V. alginolyticus. In this study, LuxS-dependent regulation of motility and flagella biogenesis, the potential virulence factors in V. alginolyticus, were further investigated. A luxS-deleted mutant showed deficiency in motility and flagella formation, and an intact luxScomplemented the defect. Since motility is flagella dependent, V. alginolyticusflagella biogenesis related genes, including the flagella regulator genes flaKand lafKand the sub-hierarchical flagellar genes fliSand lafA, were cloned and identified. Based on quantitative real-time reverse transcription-PCR, differential expression of these genes was confirmed in wild-type and luxSmutants. Our results indicate that LuxS plays an important role in the regulation of motility and flagella biogenesis in V. alginolyticus.

ABSTRACTSevere acute respiratory syndrome coronavirus-2 (SARS-CoV-2), which causes coronavirus disease-2019 (COVID-19), interacts with the host cell receptor angiotensin-converting enzyme 2 (hACE2) via its spike 1 protein during infection. After the virus sequence was published, we identified two potent antibodies against the SARS-CoV-2 receptor binding domain (RBD) from antibody libraries using a phage-to-yeast (PtY) display platform in only 10 days. Our lead antibody JMB2002, now in a Phase 1 clinical trial (ChiCTR2100042150), showed broad-spectrum in vitroblocking activity against hACE2 binding to the RBD of multiple SARS-CoV-2 variants, including B.1.351 that was reportedly much more resistant to neutralization by convalescent plasma, vaccine sera and some clinical-stage neutralizing antibodies. Furthermore, JMB2002 has demonstrated complete prophylactic and potent therapeutic efficacy in a rhesus macaque disease model. Prophylactic and therapeutic countermeasure intervention of SARS-CoV-2 using JMB2002 would likely slow down the transmission of currently emerged SARS-CoV-2 variants and result in more efficient control of the COVID-19 pandemic.

ABSTRACTVibrio fischeri, the bacterial symbiont of the Hawaiian bobtail squid, Euprymna scolopes, uses quorum sensing to control genes involved in bioluminescence, host colonization, and other biological processes. Previous work has shown that AinS/R-directed quorum sensing also regulates the expression of rpoQ(VF_A1015), a gene annotated as an RpoS-like sigma factor. In this study, we demonstrate using phylogenetics that RpoQ is related to, but distinct from, the stationary-phase sigma factor RpoS. Overexpression of rpoQresults in elevated chitinase activity but decreased motility and luminescence, three activities associated with symbiosis. The reduction in bacterial luminescence associated with the overexpression of rpoQoccurs both in culture and within the light-emitting organ of the squid host. This suppression of bioluminescence is due to the repression of the luxICDABEGpromoter. Our results highlight RpoQ as a novel regulatory component, embedded in the quorum-signaling network that controls several biological processes in V. fischeri.IMPORTANCEQuorum signaling is a widely occurring phenomenon that functions in diverse bacterial taxa. It is most often found associated with species that interact with animal or plant hosts, either as mutualists or pathogens, and controls the expression of genes critical to tissue colonization. We present the discovery of rpoQ, which encodes a new regulatory component in the quorum-signaling pathway of Vibrio fischeri. RpoQ is a novel protein in the RpoS family of stationary-phase sigma factors. Unlike many other regulatory proteins involved in the quorum-signaling pathways of the Vibrionaceae, the distribution of RpoQ appears to be restricted to only two closely related species. The role of this regulator is to enhance some quorum-signaling outputs (motility) while suppressing others (luminescence). We propose that RpoQ may be a recently evolved or acquired component in V. fischerithat provides this organism with an additional level of regulation to modulate its existing quorum-signaling pathway.