Diluted low concentration electrolyte for interphase stabilization of high-voltage LiNi_(0.5)Mn_(1.5)O_(4) cathode

The Co-free Li Ni_(0.5)Mn_(1.5)O_(4)(LNMO)is a promising cathode for lithium-ion batteries owing to its high operating voltage and low costs.However,the synthesis of LNMO is generally time and energy consuming,and its practical application is hindered by the lack of a compatible electrolyte.Herein,a spray pyrolysis-based energy-saving synthesis method as well as a diluted low concentration electrolyte(0.5 M LiPF_(6) in a mixture of fluoroethylene carbonate/dimethyl carbonate/1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether(FEC:DMC:TTE,1:4:5 by volume))are proposed to address these challenges.Owing to the unique features of the precursor prepared by spray pyrolysis,well-crystallized LNMO single-crystal can be obtained within 1 h calcination at 900℃.Besides,the fluorinated interphases derived from the diluted low concentration electrolyte not only mitigate the Mn dissolution and Al corrosion at the cathode side,but also suppresses dendritic Li deposition at the anode side,thus enabling stable cycling of both LNMO and Li metal anode.Thus,30μm Li|LNMO(1.75 m A h cm^(-2))cells achieve a high capacity retention(90.9%)after 168 cycles in the diluted low concentration electrolyte.

MoS2-Based Photodetectors Powered by Asymmetric Contact Structure with Large Work Function Difference

Self-powered devices are widely used in the detection and sensing fields.Asymmetric metal contacts provide an effective way to obtain self-powered devices.Finding two stable metallic electrode materials with large work function differences is the key to obtain highly efficient asymmetric metal contacts structures.However,common metal electrode materials have similar and high work functions,making it difficult to form an asymmetric contacts structure with a large work function difference.Herein,Mo2C crystals with low work function(3.8 eV) was obtained by chemical vapor deposition(CVD) method.The large work function difference between Mo2C and Au allowed us to synthesize an efficient Mo2C/MoS2/Au photodetector with asymmetric metal contact structure,which enables light detection without external electric power.We believe that this novel device provides a new direcfor the design of miniature self-powered photodetectors.These results also highlight the great potential of ultrathin Mo2C prepared by CVD in heterojunction device applications.

The size effect and high activity of nanosized platinum supported catalysts for low temperature oxidation of volatile organic compounds

Pt/Al_(2)O_(3) catalysts with smaller size of Pt nanoparticles were prepared by ethylene glycol reduction method in two different way and their oxidation activities for three typical VOCs(volatile organic compounds)were evaluated.The catalyst prepared by first adsorption and then reduction procedure is denoted as L-Pt/Al_(2)O_(3) while the catalyst prepared by first reduction and then loading procedure is defined as R-Pt/Al_(2)O_(3).The results show that L-Pt/Al_(2)O_(3) with the stronger interaction between Pt species and Al_(2)O_(3) exhibit smaller size of Pt nanoparticles and favorable thermal stability compared with R-Pt/Al_(2)O_(3).L-Pt/Al_(2)O_(3) is favor of the formation of more adsorbed oxygen species and more Pt^(2+)species,resulting in high catalytic activity for benzene and ethyl acetate oxidation.However,R-Pt/Al_(2)O_(3) catalysts with higher proportion of Pt^(0)/Pt^(2+)and bigger size of Pt particles exhibits higher catalytic activity for n-hexane oxidation.Pt particles in R-Pt/Al_(2)O_(3) were aggregated much more serious than that in L-Pt/Al_(2)O_(3) at the same calcination temperature.The Pt particles supported on Al_(2)O_(3) with~10 nm show the best catalytic activity for n-hexane oxidation.

Highly efficientγ-ray generation by 10 PW-class lasers irradiating heavy-ion plasmas

10 PW-class lasers irradiating overcritical plasmas in the quantum electrodynamics regime promise to generate ultrabrightγ-ray sources in the laboratory.Here using two-dimensional particle-in-cell simulations,we report highly efficientγ-ray generation in the parameter regime of 10 PW-class lasers at an intensity level of 10^(23)W cm^(–2)interaction with heavy-ion plasmas which have large-scale preplasmas.The laser-to-γ-ray(>1 MeV)energy conversion efficiency reaches close to 60%with an above 10^(14)γ-photons/pulse.The averageγ-photon energy is about 14 MeV with the highest photon energy exceeding 1 GeV.The high-energyγ-photons are mainly directed in the forward direction.We also find that plane target geometry is efficient enough for high powerγ-ray radiation,which is beneficial for easing the difficulty of complex target manufacturing and alignment in experiments.

High harmonic generation driven by twocolor relativistic circularly polarized laser pulses at various frequency ratios

High harmonic generation(HHG)by two-color counter-rotating relativistic laser pulses with arbitrary frequency ratio is investigated through particle-in-cell simulations.It is shown that the dichromatic laser driver at various frequency ratios can effectively produce high-order harmonics with different spectral features.A general selection rule of this extended scheme can be obtained and the corresponding harmonic helicity can be identified through a simple analytical model based on a relativistic oscillating mirror.Thus,the results in this paper may offer new opportunities for arbitrary spectral control of generated harmonics,which is of significance for diverse potential applications in practice.

High precision patternable liquid metal based conductor and adhesive substrate enabled stretchable hybrid systems

Stretchable hybrid systems have been attracting tremendous attention for their essential role in soft robotics,on-skin electronics,and implantable devices.Both rigid and soft functional modules are typically required in those devices.Consequently,ensuring stable electrical contact between rigid and soft modules is a vital part.Here,we propose a simple,universal,and scalable strategy for the stretchable hybrid system through a highly precise printable liquid metal particle-based conductor and adhesive fluorine rubber substrate.The properties of liquid metal particle-based conductors could be easily tuned to realize high-precision patterning,large-scale printing,and the ability to print on various substrates.Additionally,the fluorine rubber substrate could form strong interfacial adhesion with various components and materials through simply pressing and heating,hence enabling stable electrical contact.Furthermore,we prepared a stretchable hybrid light-emitting diode(LED)display system and employed it in on-skin visualization of pressure levels,which perfectly combined rigid and soft modules,thus demonstrating the promising potential applications in complex multifunctional stretchable hybrid systems for emerging technologies.

Hybrid diluents enable localized high-concentration electrolyte with balanced performance for high-voltage lithium-metal batteries

Localized high-concentration electrolytes(LHCE) have shown good compatibility with high-voltage lithium(Li)-metal batteries, but their practicality is yet to be proved in terms of cost and safety. Here we develop a hybrid-LHCE with favorable integrated properties by combining the merits of two representative diluents, fluorobenzene(FB) and 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether(TFE). Specifically,the extremely cheap and lightweight FB significantly reduces the cost and density of electrolyte, while the fire-retardant TFE circumvents the flammable nature of FB and thus greatly improves the safety of electrolyte. Moreover, the FB–TFE mixture enhances the thermodynamic stability of hybrid-LHCE and renders a controllable defluorination of FB, contributing to the formation of a thin and durable inorganic-rich solid electrolyte interphase(SEI) with rapid ion-transport kinetics. Benefiting from the designed hybridLHCE, a Li|NCM523 battery demonstrates excellent cycling performance(215 cycles, 91% capacity retention) under challenging conditions of thin Li-anode(30 μm) and high cathode loading(3.5 m Ah/cm^(2)).

Recent advances in ultrathin materials and their applications in e-skin

Intelligent technologies based on artificial intelligence and big data hold great potential for health monitoring and human–machine capability enhancement.However,electronics must be connected to the human body to realize this vision.Thus,tissue or skin-like electronics with high stretchability and low stiffness mechanical properties are highly desirable.Ultrathin materials have attracted significant attention from the research community and the industry because of their high performance and flexibility.Over the past few years,considerable progress has been made in flexible ultrathin sensors and devices based on ultrathin materials.Here,we review the developments in this area and examine representative research progress in ultrathin materials fabrication and device construction.Strategies for the fabrication of stretchable ultrathin materials and devices are considered.The relationship between the thin-film structure and performance is emphasized and highlighted.Finally,the current capabilities and limitations of ultrathin devices were explored.

Topological hinge modes in Dirac semimetals

Dirac semimetals(DSMs)are an important class of topological states of matter.Here,focusing on DSMs of band inversion type,we investigate their boundary modes from the effective model perspective.We show that in order to properly capture the boundary modes,k-cubic terms must be included in the effective model,which would drive an evolution of surface degeneracy manifold from a nodal line to a nodal point.Sizable k-cubic terms are also needed for better exposing the topological hinge modes in the spectrum.Using first-principles calculations,we demonstrate that this feature and the topological hinge modes can be clearly exhibited inβ-CuI.We extend the discussion to magnetic DSMs and show that the time-reversal symmetry breaking can gap out the surface bands and hence is beneficial for the experimental detection of hinge modes.Furthermore,we show that magnetic DSMs serve as a parent state for realizing multiple other higher-order topological phases,including higher-order Weyl-point/nodal-line semimetals and higher-order topological insulators.

Material assembly by droplet drying:From mechanics theories to applications

Evaporation of droplets composed of insoluble materials provides a low‐cost and facile route for assembling materials and structures in a wide spectrum of functionalities down to the nanoscale and also serves as a basis for innovating inksolution‐based future manufacturing technologies.This review summarizes the fundamental mechanics theories of material assembly by droplet drying both on solid and liquid substrates and in a fully suspended air environment.The evolution of assembly patterns,material deformation,and liquid flow during droplet drying and its response to external stimuli ranging from solution surfactant and pH value,surface geometric pattern and wettability,drying temperature,pressure environment,to electrical field have been highlighted to elucidate the coupling mechanisms between solid materials and liquid solutions and the manipulation strategies for material assembly through an either active or passive means.The recent progresses in ink‐based printing technologies with selected examples are also presented to illustrate the immediate applications of droplet drying,with a focus on printing electronic sensors and biomedical devices.The remaining challenges and emerging opportunities are discussed.

Synthesis of monodispersed Fe3O4@C core/shell nanoparticles

We report a facile method to synthesize dispersed Fe304@C nanoparticles （NPs）. Fe304 NPs were firstly prepared via the high temperature diol thermal decomposition method. Fe304@C NPs were fabricated using glucose as a carbon source by hydro- thermal process. The obtained products were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, vibrating sample magnetometer （VSM） and Raman spectra. The results indicate that the original shapes and magnetic property of Fe304 NPs can be well preserved. The magnetic particles are well dispersed in the carbon matrix. This strategy would provide an efficient approach for existing applications in Li-ion batteries and drug delivery. Meanwhile, it offers the raw materials to assemble future functional nanometer and micrometer superstructures.

The nonstructural protein 2C of Coxsackie B virus has RNA helicase and chaperoning activities

RNA-remodeling proteins,including RNA helicases and chaperones,play vital roles in the remodeling of structured RNAs.During viral replication,viruses require RNA-remodeling proteins to facilitate proper folding and/or re-folding the viral RNA elements.Coxsackieviruses B3(CVB3)and Coxsackieviruses B5(CVB5),belonging to the genus Enterovirus in the family Picornaviridae,have been reported to cause various infectious diseases such as hand-foot-and-mouth disease,aseptic meningitis,and viral myocarditis.However,little is known about whether CVB3 and CVB5 encode any RNA remodeling proteins.In this study,we showed that 2C proteins of CVB3 and CVB5 contained the conserved SF3 helicase A,B,and C motifs,and functioned not only as RNA helicase that unwound RNA helix bidirectionally in an NTP-dependent manner,but also as RNA chaperone that remodeled structured RNAs and facilitated RNA strand annealing independently of NTP.In addition,we determined that the NTPase activity and RNA helicase activity of 2C proteins of CVB3 and CVB5 were dependent on the presence of divalent metallic ions.Our findings demonstrate that 2C proteins of CVBs possess RNA-remodeling activity and underline the functional importance of 2C protein in the life cycle of CVBs.

Detection of False Data Injection Attacks on Load Frequency Control System with Renewable Energy Based on Fuzzy Logic and Neural Networks

Load frequency control(LFC)system may be destroyed by false data injection attacks(FDIAs)and consequently the security of the power system will be impacted.High-efficiency FDIA detection can reduce the damage and power loss to the power system.This paper defines various typical and hybrid FDIAs,and the influence of several FDIAs with different characteristics on the multi-area LFC system is analyzed.To detect various attacks,we introduce an improved data-driven method,which consists of fuzzy logic and neural networks.Fuzzy logic has the features of high applicability,robustness,and agility,which can make full use of samples.Further,we construct the LFC system on MATLAB/Simulink platform,and systematically simulate the experiments that FDIAs affect the LFC system by tampering with measurement data.Among them,considering the large-scale penetration of renewable energy with intermittency and volatility,we generate three simulation scenarios with or without renewable energy generation.Then,the performance for detecting FDIAs of the improved method is verified by simulation data samples.

Large transverse thermoelectric figure of merit in a topological Dirac semimetal

The Seebeck effect encounters a few fundamental constraints hindering its thermoelectric(TE)conversion efficiency.Most notably,there are the charge compensation of electrons and holes that diminishes this effect,and the Wiedemann-Franz(WF)law that makes independent optimization of the corresponding electrical and thermal conductivities impossible.Here,we demonstrate that in the topological Dirac semimetal Cd3As2 the Nernst effect,i.e.,the transverse counterpart of the Seebeck effect,can generate a large TE figure of merit zNT.At room temperature,zNT≈0.5 in a small field of 2 T and it significantly surmounts its longitudinal counterpart for any field.A large Nernst effect is generically expected in topological semimetals,benefiting from both the bipolar transport of compensated electrons and holes and their high mobilities.In this case,heat and charge transport are orthogonal,i.e.,not intertwined by the WF law anymore.More importantly,further optimization of zNT by tuning the Fermi level to the Dirac node can be anticipated due to not only the enhanced bipolar transport,but also the anomalous Nernst effect arising from a pronounced Berry curvature.A combination of the topologically trivial and nontrivial advantages promises to open a new avenue towards high-efficient transverse thermoelectricity.

Zigzag magnetic order in a novel tellurate compound Na_(4-δ)NiTeO_6 with S=1 chains

Na_(4-δ)Ni Te O_(6) is a rare example in the transition-metal tellurate family of realizing an S=1 spin-chain structure.By performing neutron powder diffraction measurements,the ground-state magnetic structure of Na_(4-δ)Ni Te O_(6) is determined.These measurements reveal that below T_N~6.8(2)K,the Ni^(2+) moments form a screwed ferromagnetic(FM)spin-chain structure running along the crystallographic a axis but these FM spin chains are coupled antiferromagnetically along the b and c directions,giving rise to a magnetic propagation vector of k=(0,1/2,1/2).This zigzag magnetic order is well supported by first-principles calculations.The moment size of Ni^(2+) spins is determined to be 2.1(1) μ_(B) at 3 K,suggesting a significant quenching of the orbital moment due to the crystalline electric field(CEF)effect.The previously reported metamagnetic transition near H_(c)~0.1 T can be understood as a field-induced spin-flip transition.The relatively easy tunability of the dimensionality of its magnetism by external parameters makes Na_(4-δ)Ni Te O_(6)a promising candidate for further exploring various types of novel spin-chain physics.