Selective conversion of renewable sources is necessary for developing energy generation technology and protecting the environment. Herein, this work reports a one-step controllable synthesis of trimetallic NiCoFe-layered double hydroxides (NiCoFe-LDHs) nanosheets (1.36 nm) for both an efficient oxygen evolution reaction (OER) and highly selective oxidation of biomass-derived 5-hydroxymethylfurfural (HMFOR) into value-added 2,5-furandicarboxylic acid (FDCA). For comparison, two sets of bimetallic NiCo- and NiFe-LDHs were similarly synthesized and evaluated. In the OER process, the optimal NiCoFe-LDHs nanosheets exhibited the lowest necessary overpotential (288 mV) to reach 10 mA cm–2 and the smallest Tafel slope of 92 mV dec–1 compared with NiCo-LDHs (347 mV, 115 mV dec–1) and NiFe-LDHs (303 mV, 108 mV dec–1). The performance was also superior to most previously reported LDHs catalysts. Additionally, NiCoFe-LDHs nanosheets exhibited a much smaller charge transfer resistance (Rct) of 1.0 Ω and a larger C dl value of 2.62 mF cm–2 compared with NiCo-LDHs (2.1 Ω, 1.94 mF cm–2) and NiFe-LDHs (1.4 Ω, 2.22 mF cm–2), indicating fast catalytic kinetics. Furthermore, the NiCoFe-LDHs nanosheets possessed excellent durability over 10 h, much better than that of NiCo- and NiFe-LDHs. NiCoFe-LDHs catalysts also exhibited high performance in the oxidation of 5-hydroxymethylfurfural (HMF) to FDCA, which is a key precursor for the sustainable synthesis of polymers (e.g., polyethylene 2,5-furandicarboxylate (PEF)). An ultralow overpotential of 280 mV was required to achieve 20 mA cm–2, nearly 120 mV less than the activity in pure 1.0 M NaOH. The reaction intermediates and products were qualified by liquid chromatography–mass spectroscopy system (LC-MS) and LC, where 95.5% conversion of HMF and 84.9% yield of FDCA were obtained in 1 h. The reaction kinetics and possible pathways were further investigated. As a unique report utilizing trimetallic LDHs catalysts for OER and HMFOR, this study provides a promising perspective for energy conversion and electrocatalytic processing of biomass-derived monomers.

The association of Zika virus (ZIKV) infections with microcephaly and neurological diseases has highlighted an emerging public health concern. Here, we report the crystal structure of the full‐length ZIKV nonstructural protein 1 (NS1), a major host‐interaction molecule that functions in flaviviral replication, pathogenesis, and immune evasion. Of note, a long intertwined loop is observed in the wing domain of ZIKV NS1, and forms a hydrophobic “spike”, which can contribute to cellular membrane association. For different flaviviruses, the amino acid sequences of the “spike” are variable but their common characteristic is either hydrophobic or positively charged, which is a beneficial feature for membrane binding. Comparative studies with West Nile and Dengue virus NS1 structures reveal conserved features, but diversified electrostatic characteristics on both inner and outer faces. Our results suggest different mechanisms of flavivirus pathogenesis and should be considered during the development of diagnostic tools.

We re-examine the classifications of supernovae (SNe) presented in the Lick Observatory Supernova Search (LOSS) volume-limited sample with a focus on the stripped-envelope SNe. The LOSS volumelimited sample, presented by Leaman et al. (2011) andLi et al. (2011b), was calibrated to provide meaningful measurements of SN rates in the local universe; the results presented therein continue to be used for comparisons to theoretical and modeling efforts. Many of the objects from the LOSS sample were originally classified based upon only a small subset of the data now available, however, and recent studies have both updated some subtype distinctions and improved our ability to perform robust classifications, especially for stripped-envelope SNe. We re-examine the spectroscopic classifications of all events in the LOSS volume-limited sample (180 SNe and SN impostors) and update them if necessary. We discuss the populations of rare objects in our sample including broad-lined Type Ic SNe, Ca-rich SNe, SN 1987A-like events (we identify SN 2005io as SN 1987A-like here for the first time), and peculiar subtypes. The relative fractions of Type Ia SNe, Type II SNe, and stripped-envelope SNe in the local universe are not affected, but those of some subtypes are. Most significantly, after discussing the often unclear boundary between SNe Ib and Ic when only noisy spectra are available, we find a higher SN Ib fraction and a lower SN Ic fraction than calculated by Li et al. (2011b): spectroscopically normal SNe Ib occur in the local universe 1.7 ± 0.9 times more often than do normal SNe Ic.

Unusually high velocities ( 0.1c) and correspondingly high kinetic energies have been observed in a subset of Type Ic supernovae (so-called "broad-lined Ic" supernovae; SNe Ic-BL), prompting a search for a central engine model capable of generating such energetic explosions. A clue to the explosion mechanism may lie in the fact that all supernovae that accompany long-duration gamma-ray bursts belong to the SN Ic-BL class. Using a combination of two-dimensional relativistic hydrodynamics and radiation transport calculations, we demonstrate that the central engine responsible for long gammaray bursts can also trigger a SN Ic-BL. We find that a reasonable gamma-ray burst engine injected into a stripped Wolf-Rayet progenitor produces a relativistic jet with energy ∼10 51 ergs, as well as a SN whose synthetic light curves and spectra are fully consistent with observed SNe Ic-BL during the photospheric phase. As a result of the jet's asymmetric energy injection, the SN spectra and light curves depend on viewing angle. The impact of viewing angle on the spectrum is particularly pronounced at early times, while the viewing angle dependence for the light curves (∼10 % variation in bolometric luminosity) persists throughout the photospheric phase.

Layered double hydroxide and its derived metal oxides in the transformations of biomass-derived molecules.

Super-luminous supernovae (SLSNe) are tremendously luminous explosions whose power sources and progenitors are highly debated. Broad-lined SNe Ic (SNe Ic-bl) are the only type of SNe that are connected with long-duration gamma ray bursts (GRBs). Studying the spectral similarity and difference between the populations of hydrogen-poor SLSNe (SLSNe Ic) and of hydrogen-poor stripped-envelope core-collapse SNe, in particular SNe Ic and SNe Ic-bl, can provide crucial observations to test predictions of theories based on various power source models and progenitor models. In this paper, we collected all of the published optical spectra of 32 SLSNe Ic, 21 SNe Ic-bl, as well as 17 SNe Ic, quantified their spectral features, constructed average spectra, and compared them in a systematic way using new tools we have developed. We find that SLSNe Ic and SNe Ic-bl, including those connected with GRBs, have comparable widths for their spectral features and average absorption velocities at all phases. Thus, our findings strengthen the connection between SLSNe Ic and GRBs. In particular, SLSNe Ic have average Fe II λ5169 absorption velocities of −15, 000 + / − 2, 600 km s −1 at 10 days after peak, which are higher than those of SNe Ic by ∼ 7, 000 km s −1 on average. SLSNe Ic also have significantly broader Fe II λ5169 lines than SNe Ic. Moreover, we find that such high absorption and width velocities of SLSNe Ic may be hard to explain by the interaction model, and none of 13 SLSNe Ic with measured absorption velocities spanning over 10 days has a convincing flat velocity-evolution, which is inconsistent with the magnetar model in one dimension. Lastly, we compare SN 2011kl, the first SN connected with an ultra-long GRB, with the mean spectrum of SLSNe Ic and of SNe Ic-bl.

Unlike the ordinary supernovae (SNe) some of which are hydrogen and helium deficient (called Type Ic SNe), broadlined Type Ic SNe (SNe Ic-bl) are very energetic events, and all SNe coincident with bona fide long duration gamma-ray bursts (LGRBs) are of Type Ic-bl. Understanding the progenitors and the mechanism driving SN Ic-bl explosions vs those of their SNe Ic cousins is key to understanding the SN-GRB relationship and jet production in massive stars. Here we present the largest set of host-galaxy spectra of 28 SNe Ic and 14 SN Ic-bl, all discovered before 2013 by the same untargeted survey, namely the Palomar Transient Factory (PTF). We carefully measure their gas-phase metallicities, stellar masses (M * s) and star-formation rates (SFRs) by taking into account recent progress in the metallicity field and propagating uncertainties correctly. We further re-analyze the hosts of 10 literature SN-GRBs using the same methods and compare them to our PTF SN hosts with the goal of constraining their progenitors from their local environments by conducting a thorough statistical comparison, including upper limits. We find that the metallicities, SFRs and M * s of our PTF SN Ic-bl hosts are statistically comparable to those of SN-GRBs, but significantly lower than those of the PTF SNe Ic. The mass-metallicity relations as defined by the SNe Ic-bl and SN-GRBs are not significantly different from the same relations as defined by the SDSS galaxies, in contrast to claims by earlier works. Our findings point towards low metallicity as a crucial ingredient for SN Ic-bl and SN-GRB production since we are able to break the degeneracy between high SFR and low metallicity. We suggest that the PTF SNe Ic-bl may have produced jets that were choked inside the star or were able break out of the star as unseen low-luminosity or off-axis GRBs.

The outbreak of COVID‐19 revealed the vulnerability of commercially available face masks. Without having antibacterial/antiviral activities, the current masks act only as filtering materials of the aerosols containing microorganisms. Meanwhile, in surgical masks, the viral and bacterial filtration highly depends on the electrostatic charges of masks. These electrostatic charges disappear after 8 h, which leads to a significant decline in filtration efficiency. Therefore, to enhance the masks’ protection performance, fabrication of innovative masks with more advanced functions is in urgent demand. This review summarizes the various functionalizing agents which can endow four important functions in the masks including i) boosting the antimicrobial and self‐disinfectant characteristics via incorporating metal nanoparticles or photosensitizers, ii) increasing the self‐cleaning by inserting superhydrophobic materials such as graphenes and alkyl silanes, iii) creating photo/electrothermal properties by forming graphene and metal thin films within the masks, and iv) incorporating triboelectric nanogenerators among the friction layers of masks to stabilize the electrostatic charges and facilitating the recharging of masks. The strategies for creating these properties toward the functionalized masks are discussed in detail. The effectiveness and limitation of each method in generating the desired properties are well‐explained along with addressing the prospects for the future development of masks.