Arctic ozone loss in early spring and its impact on the stratospheretroposphere coupling

The tropospheric impact of Arctic ozone loss events is still debatable.In this study we investigate that question,using the ERA5 reanalysis and long-term integration by a climate-chemistry coupled model(CESM2-WACCM).We begin with the frequency of Arctic ozone loss events.On average,such events occur once in early spring every 14−15 years in ERA5 data and in the model,both of which estimate that roughly 40%of the strong polar vortex events in March are coupled with Arctic ozone loss,the remaining 60%being uncoupled.The composite difference between the two samples might be attributed to the pure impact of the Arctic ozone loss-that is,to ozone loss alone,without the concurrent impact of strong polar vortices.Arctic ozone loss is accompanied by an increase in total ozone in midlatitudes,with the maximum centered in the Central North Pacific.Contrasting Arctic ozone loss events with pure strong polar vortex events that are uncoupled with ozone loss,observations confirm that the stratospheric Northern Annular Mode reverses earlier for the former.For pure strong vortex events in early spring(without Arctic ozone loss),the cold anomalies can extend from the stratosphere to the middle troposphere;when such events are strong,the near surface warm anomalies are biased toward the continents.In contrast,during the other 40%of strong early-spring polar vortex events,those coupled with ozone loss,a concurrent and delayed warming of the near surface over the Arctic and its neighboring areas is observed,due to vertical redistribution of solar radiation by the change in the ozone.

Fabrication and application of a graphene polarizer with strong saturable absorption

By transferring 100 nm gold-coated CVD monolayer graphene onto the well-polished surface of D-shaped fiber, we achieve a graphene in-line polarizer with a high polarization extinction ratio of ~27 d B and low insertion loss of 5 d B at 1550 nm, meanwhile achieving a strong saturable absorption effect of 14%. The manufacture of this graphene in-line polarizer also simplifies the graphene transfer process. To explore the potential applications of the new device, we also demonstrate noise-like pulse generation and supercontinuum spectrum generation. By launching the designed graphene device into a fiber ring laser cavity, 51 nm bandwidth noise-like pulse is obtained. Then, launching the high-power noise-like pulse into high nonlinear fiber, a 1000 nm wide supercontinuum spectrum is obtained, which is favorable for sensing and nonlinearities scientific fields.

Behavior of the relativistic angular and energy distributions of atoms exposed to a strong and low-frequency circularly polarized laser field

In this Letter, we focus on the theoretical analysis of the relativistic energy and angular distributions of the ejected photoelectrons during the relativistic tunnel ionization of atoms by intense, circularly polarized light. We make a small modification of the general analytical expressions for these distributions. The role of the initial momentum, the ponderomotive potential, and the Stark shift are considered. We also present the maximal angle of electron emission.

Synergistic engineering of cobalt selenide and biomass-derived S,N,P co-doped hierarchical porous carbon for modulation of stable Li-S batteries

Hierarchical porous carbon co-doped with heterogeneous atoms has attracted much attention thanks to sizable internal void space accommodating electrolyte,high-density microporous structure physically con-fining polysulfides(LPS),and heterogeneous atoms serving as active sites to capture LPS.However,solely relying on carbon material defects to capture LPS proves ineffective.Hence,metal compounds must be introduced to chemisorb LPS.Herein,cobalt ions are in-situ grown on the polydopamine layer coated on the surface of biomass-derived S,N,P co-doped hierarchical porous carbon(SNP-PC).Then a layer of nitrogen-doped porous carbon(MPC)dotted with CoSe nanoparticles is acquired by selenizing.Thus,a strong-polar/weak-polar composite material of SNP-PC studded with CoSe nanoparticles is obtained(SNP-PC@MPC@CoSe).Button cells assembled with SNP-PC@MPC@CoSe-modified separator enable superb long-cycle stability and satisfactory rate performance.An excellent rate capacity of 796 mAh g^(−1)at a high current rate of 4 C with an ultra-low capacity fading of 0.06%over 700 cycles can be acquired.More impressively,even in a harsh test condition of 5.65 mg cm^(−2)sulfur loading and 4μL mg^(−1)ratio of electrolyte to active materials,the battery can still display a specific capacity of 980 mAh g^(−1)(area capacity of∼5.54 mAh cm^(−2))at 0.1 C.This work provides a promising route toward high-performance Li-S batteries.

Confining sulfur in sandwich structure of bamboo charcoal and aluminum fluoride(BC@S@AlF3) as a long cycle performance cathode for Li-S batteries

The ’shuttle effect’ of polysulfide causing rapid capacity fade and low coulo mbic efficiency of high ene rgy storage lithium-sulfur(Li-S) batteries.Herein,a sandwich structure of bamboo charcoal/sulfur coating by aluminum fluoride(BC@S@AlF3) composites is designed and fabricated for the first time.The as-designed cathode exhibited excellent electrochemical properties and stable capacity retention.The initial capacity reaches 1119 mA h/g and the capacity after 100 cycles is 869 mA h/g at 0.5 C,which is much stable than that of composite materials without bamboo charcoal or AlF3 coating.Moreover,the BC@S@AlF3 cathode presents excellent long-term capacity stability with a capacity decay of 0.073% per cycle during 500 charge/discharge cycles at 1 C,offering a potential for use in high energy Li-S batteries.The physical confinement,chemical ancho ring,and catalysis conversion for active sulfur are achieved simultaneously with the AlF3 coating and bamboo charcoal core with porous structure.