High-performance Si-Containing anode materials in lithium-ion batteries: A superstructure of Si@Co-NC composite works effectively

To mitigate the massive volume expansion of Si-based anode during the charge/discharge cycles,we synthesized a superstructure of Si@Co±NC composite via the carbonization of zeolite imidazolate frameworks incorporated with Si nanoparticles.The Si@Co±NC is comprised of Sinanoparticle core and N-doped/Co-incorporated carbon shell,and there is void space between the core and the shell.When using as anode material for LIBs,Si@Co±NC displayed a super performance with a charge/discharge capacity of 191.6/191.4 mA h g^(-1)and a coulombic efficiency of 100.1%at 1000 mA g^(-1)after 3000 cycles,and the capacity loss rate is 0.022%per cycle only.The excellent electrochemical property of Si@Co±NC is because its electronic conductivity is enhanced by doping the carbon shell with N atoms and by incorporating with Co particles,and the pathway of lithium ions transmission is shortened by the hollow structure and abundant mesopores in the carbon shell.Also,the volume expansion of Si nanoparticles is well accommodated in the void space and suppressed by the carbon host matrix.This work shows that,through designing a superstructure for the anode materials,we can synergistically reduce the work function and introduce the confinement effect,thus significantly enhancing the anode materials’electrochemical performance in LIBs.

The circumstellar matter of type II intermediate luminosity optical transients(ILOTs)

I find that a≃0.1−1M⊙outflowing equatorial dusty disk(torus)that the binary system progenitor of an intermediate luminosity optical transient(ILOT)ejects several years to several months before and during the outburst can reduce the total emission to an equatorial observer by two orders of magnitude and shifts the emission to wavelengths of mainlyλ≳10μm.This is termed a type II ILOT(ILOT II).To reach this conclusion,I use calculations of type II active galactic nuclei and apply them to the equatorial ejecta(disk/torus)of ILOTs II.This reduction in emission can last for tens of years after outburst.Most of the radiation escapes along the polar directions.The attenuation of the emission for wavelengths ofλ<5μm can be more than three orders of magnitude,and the emission atλ\lessim2μm is negligible.Jets that the binary system launches during the outburst can collide with polar CSM and emit radiation above the equatorial plane and dust in the polar outflow can reflect emission from the central source.Therefore,during the event itself the equatorial observer might detect an ILOT.I strengthen the previously suggested ILOT II scenario to the event N6946-BH1,where a red giant star disappeared in the visible.

Amplifying magnetic fields of a newly born neutron star by stochastic angular momentum accretion in core collapse supernovae

I present a novel mechanism to boost magnetic field amplification of newly born neutron stars in core collapse supernovae.In this mechanism,that operates in the jittering jets explosion mechanism and comes on top of the regular magnetic field amplification by turbulence,the accretion of stochastic angular momentum in core collapse supernovae forms a neutron star with strong initial magnetic fields but with a slow rotation.The varying angular momentum of the accreted gas,which is unique to the jittering jets explosion mechanism,exerts a varying azimuthal shear on the magnetic fields of the accreted mass near the surface of the neutron star.This,I argue,can form an amplifying effect which I term the stochastic omega(Sω) effect.In the common αω dynamo the rotation has constant direction and value,and hence supplies a constant azimuthal shear,while the convection has a stochastic behavior.In the Sω dynamo the stochastic angular momentum is different from turbulence in that it operates on a large scale,and it is different from a regular rotational shear in being stochastic.The basic assumption is that because of the varying direction of the angular momentum axis from one accretion episode to the next,the rotational flow of an accretion episode stretches the magnetic fields that were amplified in the previous episode.I estimate the amplification factor of the Sω dynamo alone to be ≈ 10.I speculate that the Sω effect accounts for a recent finding that many neutron stars are born with strong magnetic fields.

长期培养和宏组学分析揭示了烃污染环境中的甲基营养型产甲烷途径

针对石油烃污染的厌氧环境,利用微生物的代谢作用将石油烃转化为甲烷是一种潜在的生物修复策略。然而,目前对于微生物厌氧烃降解产甲烷的机制尚不清楚。经过十年的持续富集和转接培养,我们获得了一种能够降解正构烷烃(C_(15)~C_(20))并且产甲烷富集培养体系,并且经过转接培养该培养物在甲烷生产的动力学特性方面得到了持续的提高。综合宏基因组和宏转录组的分析结果,发现正构烷烃主要通过Desulfosarcinaceae、Firmicutes和Synergistetes菌通过富马酸加成的方式进行起始活化,然后在Tepidiphilus菌的协同作用下进一步降解。同时,体系中含量较多的Anaerolineaceae菌主要负责死细胞生物质的回收。根据宏转录组学分析结果,甲烷主要通过H2依赖型的甲基营养甲烷途径产生,主要由候选门Verstraetearchaeta内的Methanomethyliaceae通过利用死细胞生物质回收代谢过程中产生的三甲胺来产生甲烷。这些发现表明,依赖H2的甲基营养产甲烷菌以及甲基营养产甲烷菌可能在含石油烃的地下生态系统的碳循环过程中发挥着重要的作用。

Polyvinylamine-Based Facilitated Transport Membranes for Post-Combustion CO_(2) Capture:Challenges and Perspectives from Materials to Processes

Carbon dioxide(CO_(2))capture by gas-separation membranes has become increasingly attractive due to its high energy efficiency,relatively low cost,and environmental impact.Polyvinylamine(PVAm)-based facilitated transport(FT)membranes were developed in the last decade for CO_(2) capture.This work discusses the challenges of applying PVAm-based FT membranes from materials to processes for postcombustion CO_(2) capture in power plants and cement factories.Experiences learned from a pilot demonstration system can be used to guide the design of other membranes for CO_(2) capture.The importance of module and process design is emphasized in the achievement of a high-performance membrane system.Moreover,the results from process simulation and cost estimation indicate that a three-stage membrane system is feasible for achieving a high CO_(2) purity of 95 vol%.The specific CO_(2) capture cost was found to significantly depend on the required CO_(2) capture ratio,and a moderate CO_(2) capture ratio of 50%presented a cost of 63.7USD per tonne CO_(2) captured.Thus,FT membrane systems were found to be more competitive for partial CO_(2) capture.

Continuous-flow photochemistry: An expanding horizon of sustainable technology

Understanding the unique characteristics of continuous-flow photochemistry will lead to a paradigm shift in the way we enhance sustainability and wellbeing.In this mini-review,we first provide a succinct overview of working principles of this technique and discuss several recent synthetic protocols.Then,emphasis is given to those representative examples which address environmental issues such as indoor air pollutants and water contamination.Finally,recent progress made using this technique to deal with rising CO2 emission,solar energy utilization and biomedical equipment is described.It is believed that this mini-review could inspire more chemists to utilize this technique in their research,either in the academic or industrial field.

Reviving the stalled shock by jittering jets in core collapse supernovae: jets from the standing accretion shock instability

I present a scenario by which an accretion flow with alternating angular momentum on to a newly born neutron star in a core collapse supernova(CCSN) efficiently amplifies magnetic fields and by that launches jets.The accretion flow of a collapsing core on to the newly born neutron star suffers spiral standing accretion shock instability(SASI).This instability leads to a stochastically variable angular momentum of the accreted gas,which in turn forms an accretion flow with alternating directions of the angular momentum,and hence alternating shear,at any given time.I study the shear in this alternating-shear sub-Keplerian inflow in published simulations,and present a new comparison with Keplerian accretion disks.From that comparison I argue that it might be as efficient as Keplerian accretion disks in amplifying magnetic fields by a dynamo.I suggest that although the average specific angular momentum of the accretion flow is small,namely,sub-Keplerian,this alternating-shear accretion flow can launch jets with varying directions,namely,jittering jets.Neutrino heating is an important ingredient in further energizing the jets.The jittering jets locally revive the stalled accretion shock in the momentarily polar directions,and by that they explode the star.I repeat again my call for a paradigm shift from a neutrino-driven explosion of CCSNe to a jet-driven explosion mechanism that is aided by neutrino heating.

Explaining recently studied intermediate luminosity optical transients(ILOTs)with jet powering

We apply the jet-powered ILOT scenario to two recently studied intermediate luminosity optical transients(ILOTs),and find the relevant shell mass and jets’energy that might account for the outbursts of these ILOTs.In the jet-powered ILOT scenario,an accretion disk around one of the stars of a binary system launches jets.The interaction of the jets with a previously ejected slow shell converts kinetic energy to thermal energy,part of which is radiated away.We apply two models of the jet-powered ILOT scenario.In the spherical shell model,the jets accelerate a spherical shell,while in the cocoon toy model the jets penetrate into the shell and inflate hot bubbles,the cocoons.We find consistent results.For the ILOT(ILRT:intermediate luminosity red transient)SNhunt120 we find the shell mass and jets’energy to be Ms■0.5-1 M☉and E2 j■5×10^(47)erg,respectively.The jets’half opening angle isαj■30°-60°.For the second peak of the ILOT(luminous red nova)AT 2014 ej we find these quantities to be Ms1-2 M☉and E2 j1.5×10^(48)erg,withαj■20°-30°.The models cannot tell whether these ILOTs were powered by a stellar merger that leaves one star,or by mass transfer where both stars survived.In both cases the masses of the shells and energies of the jets suggest that the binary progenitor system was massive,with a combined mass of M1+M210■M☉.

Uplifted cool gas and heating by mixing in cooling flows

We analyze our earlier three-dimensional hydrodynamical numerical simulation of jet-inflated bubbles in cooling flow clusters, and find that dense gas that was not heated by the jets＇ activity and that resides around the hot jet-inflated bubbles can be identified as uplifted gas as observed in some clusters. During the build up of the dense gas around the hot bubble, mixing of hot bubble gas with other regions of the intracluster medium （ICM） heats the ICM. The vortices that mix the ICM with the hot bubble gas also excite shock waves, sound waves and turbulence. Sound waves, shocks, turbulence and uplifted gas might be easier to detect than the mixing process and hence attract more attention, but we argue that the contributions of these processes to the heating of the ICM do not add up to the level of contribution of the mixing-heating process.

From capture to transport:A review of engineered surfaces for fog collection

Collecting microscale water droplets suspended in the wind,that is,fog,using permeable surfaces is a promising solution to the worldwide problem of water scarcity and is of great interest to industries,such as mist elimination and recapturing water in cooling towers.In the past few decades,this topic has attracted a drastically increasing number of researchers across a wide range of subjects.However,many aspects remain unclear,such as the definition and process of fog collection,fog collection determined from the perspectives of both the fog capture process and the liquid transport process,and how surface characteristics affect fog collection performance.In this review,we introduce and discuss fog collection from the perspectives of aerodynamics-governed fog-capturing processes and interfacial-phenomena-determined liquid transport processes.Then,an emphasis is given to the design and engineering of permeable surfaces at different length scales to optimize the fog collection performance,including the dimension,morphology,and arrangement of wires at the millimetric scale,unidirectional spreading,and Laplace pressure gradient induced by asymmetric surface geometry and nano-/microstructures.At last,a brief outlook of future research directions is provided.

NiO@Ni nanoparticles embedded in N-doped carbon for efficient photothermal CO_(2) methanation coupled with H_(2)O splitting

Photothermal carbon dioxide(CO_(2))methanation has attracted increasing interest in solar fuel synthesis,which employs the advantages of photocatalytic H_(2)O splitting as a hydrogen source and photothermal catalytic CO_(2) reduction.This work prepared three-dimensional(3D)honeycomb N-doped carbon(NC)loaded with core–shell NiO@Ni nanoparticles generated in situ at 500℃(NiO@Ni/NC-500).Under the photothermal catalysis(200℃,1.5 W/cm^(2)),the CH_(4) evolution rate of NiO@Ni/NC-500 reached 5.5 mmol/(g·h),which is much higher than that of the photocatalysis(0.8 mmol/(g·h))and the thermal catalysis(3.7 mmol/(g·h)).It is found that the generated localized surface plasmon resonance enhances the injection of hot electrons from Ni to NiO,while thermal heating accelerates the thermal motion of radicals,thus generating a strong photo-thermal synergistic effect on the reaction.The CO_(2) reduction to CH_(4) follows the*OCH pathway.This work demonstrates the synergistic effect of NiO@Ni and NC can enhance the catalytic performance of photothermal CO_(2) reduction reaction coupled with water splitting reaction.

The class of supernova progenitors that result from fatal common envelope evolution

I construct the class of supernovae and supernova progenitors that result from fatal common envelope evolution(CEE). The fatal CEE progenitors are stellar binary systems where a companion spirals-in inside the envelope of a giant star and merges with the core. The companion can be a neutron star(NS;or a black hole) that destroys the core and by that forms a common envelope jets supernova(CEJSN), a white dwarf(WD) that merges with the core to form a massive WD that later might explode as a Type Ia supernova(the core degenerate scenario), or a main sequence companion. In the latter case the outcome might be a core collapse supernova(CCSN) of a blue giant, a CCSN of type IIb or of type Ib. In another member of this class two giant stars merge and the two cores spiral-in toward each other to form a massive core that later explodes as a CCSN with a massive circumstellar matter(CSM). I discuss the members of this class, their characteristics, and their common properties. I find that fatal CEE events account for ≈6%-10% of all CCSNe, and raise the possibility that a large fraction of peculiar and rare supernovae result from the fatal CEE. The study of these supernova progenitors as a class will bring insights on other types of supernova progenitors, as well as on the outcome of the CEE.

Role of composition and grain size in controlling the structure sensitive magnetic properties of Sm substituted nanocrystalline Co-Zn ferrites

The nanocrystalline samarium substituted Co-Zn ferrites with chemical formula Co0.7Zn0.3SmyFe2-yO4(where y=0,0.01,0.02,0.03,0.04) were synthesized by sol-gel autocombustion route.The analysis of Xray diffractograms(XRD) reveals the formation of cubic spinel structure.The planes indexed from XRD analyses were confirmed in the selected area electron diffraction(SAED) image of the sample.Nanocrystalline nature of the particles in the ferrite samples was confirmed by TEM.The morphology was analyzed by scanning electron microscopy(SEM).Magnetic measurements show an increase in the magnetization for x ≤0.03.The decrease in magnetization due to spin canting is observed for x=0.04.The coercivity depends on Sm3+doping concentration,grain size and saturation magnetization.The complex permeability of the ferrites was analyzed as the function of frequency and Sm3+composition(y).The real part of complex permeability varies linearly with the grain size.

Beyond biogeographic patterns:Processes shaping the microbial landscape in soils and sediments along the Yangtze River

Deciphering biogeographic patterns of microorganisms is important for evaluating the maintenance of microbial diversity with respect to the ecosystem functions they drives.However,ecological processes shaping distribution patterns of microorganisms across large spatial‐scale watersheds remain largely unknown.Using Illumina sequencing and multiple statistical methods,we characterized distribution patterns and maintenance diversity of microorganisms(i.e.,archaea,bacteria,and fungi)in soils and sediments along the Yangtze River.Distinct microbial distribution patterns were found between soils and sediments,and microbial community similarity significantly decreased with increasing geographical distance.Physicochemical properties showed a larger effect on microbial community composition than geospatial and climatic factors.Archaea and fungi displayed stronger species replacements and weaker environmental constraints in soils than that in sediments,but opposite for bacteria.Archaea,bacteria,and fungi in soils showed broader environmental breadths and stronger phylogenetic signals compared to those in sediments,suggesting stronger environmental adaptation.Stochasticity dominated community assemblies of archaea and fungi in soils and sediments,whereas determinism dominated bacterial community assembly.Our results have therefore highlighted distinct microbial distribution patterns and diversity maintenance mechanisms between soils and sediments,and emphasized important roles of species replacement,environmental adaptability,and ecological assembly processes on microbial landscape.Our findings are helpful in predicting loss of microbial diversity in the Yangtze River Basin,and might assist the establishment of environmental policies for protecting fragile watersheds.

B(C6F5)3-Catalyzed sp3 C-Si Bond Forming Consecutive Reactions

Transition metal-catalyzed hydrosilylation is one of the most widely utilized reduction methods as an alternative to hydrogenation in academia and industry.One feature distinct from hydrogenation would be able to install sp3 C—Si bond(s)onto substrates skeleton vio hydrosilylation of alkenes.Recently,B(C6F5)3 with hydrosilanes has been demonstrated to be an efficient,metal-free catalyst system for the consecutive transformation of heteroatom-containing substrates accompanied by the formation of sp3 C—Si bond(s),which has not been realized thus far under the transition meta卜catalyzed hydrosilylative conditions.In this review,I outline the B(C6F5)3-mediated consecutive hydrosilylations of heteroarenes containing quinolines,pyridines,and furans,and of conjugated nitriles/imines to provide a new family of compounds having sp?C—Si bond(s)with high chemo-,regio-and/or stereoselectivities.The silylative cascade conversion of unactivated A/-aryl piperidines to sila-/V-heterocycles catalyzed by B(C6F5)3 involving consecutive dehydrogenation,hydrosilylation,and intramolecular C(sp2)—H silylation,is presented in another section.Chemical selectivity and mechanism of the boron catalysis focused on the sp3 C—Si bond formation are highlighted.

Cu-bearing high-entropy alloys with excellent antiviral properties

The worldwide outbreak of COVID-19 since December 2019 has caused great challenges to health organizations,and brought tremendous impact on the global economy.There have been over62.3 million confirmed infection cases and 1.4 million deaths reported until now(December 1 st,2020),and the numbers are still growing[1].Although not as influential as COVID-19.

Supernovae Ia in 2017:a long time delay from merger/accretion to explosion

I use recent observational and theoretical studies of type Ia supernovae(SNe Ia) to further constrain the viable SN Ia scenarios and to argue that there must be a substantial time delay between the end of the merger of the white dwarf(WD) with a companion or the end of mass accretion on to the WD and its terminal explosion. This merger/accretion to explosion delay(MED) is required to allow the binary system to lead to a more or less spherical explosion and to prevent a pre-explosion ionizing radiation. Considering these recent results and the required MED, I conclude that the core degenerate scenario is somewhat more favorable over the other scenarios, followed by the double degenerate scenario. Although the single degenerate scenario is viable as well, it is less likely to account for common(normal) SN Ia. As all scenarios require substantial MED, the MED has turned from a disadvantage of the core degenerate scenario to a challenge that theory should overcome. I hope that the requirement for a MED will stimulate the discussion of the different SN Ia scenarios and the comparison of the scenarios to each other.