Dynamically enhanced Autler–Townes splitting by orthogonal XUV fields

Based on numerical solutions of the time-dependent Schr ¨odinger equation, we theoretically investigate the photoelectron spectrum of hydrogen atoms ionized by a pair of ultrashort, intense, and orthogonally polarized laser pulses with a relative time delay in a pump–probe configuration. The pump pulse resonantly excites electrons from the 1s and 2p levels,inducing Rabi oscillations. The resulting dynamically enhanced Autler–Townes(AT) splitting is observed in the photoelectron energy spectrum upon interaction with the second probe pulse. In contrast to the previous parallel-polarization scheme, the proposed orthogonal-polarization configuration enables the resolution of dynamically enhanced AT splitting over a considerably wider range of probe photon energies.

Seismic anisotropy and upper mantle dynamics in Alaska:A review of shear wave splitting analyses

Shear wave splitting(SWS)is regarded as the most effective geophysical method to delineate mantle flow fields by detecting seismic azimuthal anisotropy in the earth's upper mantle,especially in tectonically active regions such as subduction zones.The Aleutian-Alaska subduction zone has a convergence rate of approximately 50 mm/yr,with a trench length reaching nearly 2800 km.Such a long subduction zone has led to intensive continental deformation and numerous strong earthquakes in southern and central Alaska,while northern Alaska is relatively inactive.The sharp contrast makes Alaska a favorable locale to investigate the impact of subduction on mantle dynamics.Moreover,the uniqueness of this subduction zone,including the unusual subducting type,varying slab geometry,and atypical magmatic activity and composition,has intrigued the curiosity of many geoscientists.To identify different sources of seismic anisotropy beneath the Alaska region and probe the influence of a geometrically varying subducting slab on mantle dynamics,extensive SWS analyses have been conducted in the past decades.However,the insufficient station and azimuthal coverage,especially in early studies,not only led to some conflicting results but also strongly limited the in-depth investigation of layered anisotropy and the estimation of anisotropy depth.With the completion of the Transportable Array project in Alaska,recent studies have revealed more detailed mantle structures and characteristics based on the dense station coverage and newly collected massive seismic data.In this study,we review significant regional-and continental-scale SWS studies in the Alaska region and conclude the mantle flow fields therein,to understand how a geometrically varying subducting slab alters the regional mantle dynamics.The summarized mantle flow mechanisms are believed to be conducive to the understanding of seismic anisotropy patterns in other subduction zones with a complicated tectonic setting.

关于EDC裂解装置TLE结焦及换热控制问题的探讨

针对采用美国西方化学技术的EDC裂解装置,分析了在高负荷(设计负荷的105%~110%)运行条件下,影响TLE管侧内壁结焦及换热的主要因素,并总结了对应的控制措施,实施后达到了延长EDC裂解装置良性运行周期的目的。

Insights on advanced substrates for controllable fabrication of photoanodes toward efficient and stable photoelectrochemical water splitting

Conversion of solar energy into H_(2) by photoelectrochemical(PEC)water splitting is recognized as an ideal way to address the growing energy crisis and environmental issues.In a typical PEC cell,the construction of photoanodes is crucial to guarantee the high efficiency and stability of PEC reactions,which fundamentally rely on rationally designed semiconductors(as the active materials)and substrates(as the current collectors).In this review work,we start with a brief introduction of the roles of substrates in the PEC process.Then,we provide a systematic overview of representative strategies for the controlled fabrication of photoanodes on rationally designed substrates,including conductive glass,metal,sapphire,silicon,silicon carbide,and flexible substrates.Finally,some prospects concerning the challenges and research directions in this area are proposed.

Recent advances in cobalt phosphide-based materials for electrocatalytic water splitting:From catalytic mechanism and synthesis method to optimization design

Electrochemical water splitting has long been considered an effective energy conversion technology for trans-ferring intermittent renewable electricity into hydrogen fuel,and the exploration of cost-effective and high-performance electrocatalysts is crucial in making electrolyzed water technology commercially viable.Cobalt phosphide(Co-P)has emerged as a catalyst of high potential owing to its high catalytic activity and durability in water splitting.This paper systematically reviews the latest advances in the development of Co-P-based materials for use in water splitting.The essential effects of P in enhancing the catalytic performance of the hydrogen evolution reaction and oxygen evolution reaction are first outlined.Then,versatile synthesis techniques for Co-P electrocatalysts are summarized,followed by advanced strategies to enhance the electrocatalytic performance of Co-P materials,including heteroatom doping,composite construction,integration with well-conductive sub-strates,and structure control from the viewpoint of experiment.Along with these optimization strategies,the understanding of the inherent mechanism of enhanced catalytic performance is also discussed.Finally,some existing challenges in the development of highly active and stable Co-P-based materials are clarified,and pro-spective directions for prompting the wide commercialization of water electrolysis technology are proposed.

Variations of shear-wave splitting parameters in the source region of the 2023 Türkiye doublet earthquakes

In this study,the shear-wave splitting parameters of local seismic events from the source regions of the 2023 Türkiye MW7.7 and MW7.6 doublet earthquakes(event 1 and event 2,respectively)were measured from June 1,2022,to April 25,2023,and their spatiotemporal characteristics were analyzed.The results revealed clear spatial and temporal differences.Spatially,the dominant fast-wave polarization direction at each station shows a strong correlation with the direction of the maximum horizontal principal compressive stress,as characterized by focal mechanism solutions of seismic events(MW≥3.5)near the station.The dominant fast-wave polarization direction and the regional stress field also showed a strong correlation with the intermovement of the Arabian Plate,African Plate,and Anatolian Block.Along the Nurdagi-Pazarcik fault zone,the seismic fault of event 1,stations closer to the middle of the fault where the mainshock occurred exhibited notably greater delay times than stations located towards the ends of the fault and far from the mainshock.In addition,the stations located to the east of the Nurdagi-Pazarcik fault and to the north of the Sürgüfault also exhibited large delay times.The spatial distribution of shear-wave splitting parameters obtained from each station indicates that the upper-crust anisotropy in the source area is mainly controlled by the regional stress field,which is closely related to the state of the block motion.During the seismogenic process of the MW7.7 earthquake,more stress accumulated in the middle of the Nurdagi-Pazarcik fault than at either end of the fault.Under the influence of the MW7.7 and MW7.6 events,the stress that accumulated during the seismogenic process of the earthquake doublet may have migrated towards some areas outside the aftershock intensive area after the earthquakes,and the crustal stress and its adjustment range near the outer stations increased significantly.With the exception of two stations with few effective events,all stations showed a consistent change in shear-wave splitting parameters over time.In particular,each station showed a decreasing trend in delay times after the doublet earthquakes,reflecting the obvious intensification of crustal stress adjustment in the seismogenic zone after the doublet earthquakes.With the occurrence of the earthquake doublet and a large number of aftershocks,the stress accumulated during the seismogenic process of the doublet earthquakes is gradually released,and then the adjustment range of crustal stress is also gradually reduced.

Acoustic Bilayer Gradient Metasurfaces for Perfect and Asymmetric Beam Splitting

We experimentally and theoretically present a paradigm for the accurate bilayer design of gradient metasurfaces for wave beam manipulation,producing an extremely asymmetric splitting effect by simply tailoring the interlayer size.This concept arises from anomalous diffraction in phase gradient metasurfaces and the precise combination of the phase gradient in bilayer metasurfaces.Ensured by different diffraction routes in momentum space for incident beams from opposite directions,extremely asymmetric acoustic beam splitting can be generated in a robust way,as demonstrated in experiments through a designed bilayer system.Our work provides a novel approach and feasible platform for designing tunable devices to control wave propagation.

How to apply ex-vivo split liver transplantation safely and feasibly: A three-step approach

BACKGROUND Given the current organ shortage crisis,split liver transplantation(SLT)has emerged as a promising alternative for select end-stage liver disease patients.AIM To introduce an ex-vivo liver graft splitting approach and evaluate its safety and feasibility in SLT.METHODS A retrospective analysis was conducted on the liver transplantation data from cases performed at our center between April 1,2022,and May 31,2023.The study included 25 SLT cases and 81 whole liver transplantation(WLT)cases.Total ex-vivo liver splitting was employed for SLT graft procurement in three steps.Patient outcomes were determined,including liver function parameters,postoperative complications,and perioperative mortality.Group comparisons for categorical variables were performed using theχ²-test.RESULTS In the study,postoperative complications in the 25 SLT cases included hepatic artery thrombosis(n=1)and pulmonary infections(n=3),with no perioperative mortality.In contrast,among the 81 patients who underwent WLT,complications included perioperative mortality(n=1),postoperative pulmonary infections(n=8),abdominal infection(n=1),hepatic artery thromboses(n=3),portal vein thrombosis(n=1),and intra-abdominal bleeding(n=5).Comparative analysis demonstrated significant differences in alanine aminotransferase(176.0 vs 73.5,P=0.000)and aspartate aminotransferase(AST)(42.0 vs 29.0,P=0.004)at 1 wk postoperatively,and in total bilirubin(11.8 vs 20.8,P=0.003)and AST(41.5 vs 26.0,P=0.014)at 2 wk postoperatively.However,the overall incidence of complications was comparable between the two groups(P>0.05).CONCLUSION Our findings suggest that the total ex-vivo liver graft splitting technique is a safe and feasible approach,especially under the expertise of an experienced transplant center.The approach developed by our center can serve as a valuable reference for other transplantation centers.

Alternating spin splitting of electronic and magnon bands in two-dimensional altermagnetic materials

Unconventional antiferromagnetism dubbed as altermagnetism was first discovered in rutile structured magnets,which is featured by spin splitting even without the spin–orbital coupling effect.This interesting phenomenon has been discovered in more altermagnetic materials.In this work,we explore two-dimensional altermagnetic materials by studying two series of two-dimensional magnets,including MF4 with M covering all 3d and 4d transition metal elements,as well as TS2 with T=V,Cr,Mn,Fe.Through the magnetic symmetry operation of RuF4 and MnS2,it is verified that breaking the time inversion is a necessary condition for spin splitting.Based on symmetry analysis and first-principles calculations,we find that the electronic bands and magnon dispersion experience alternating spin splitting along the same path.This work paves the way for exploring altermagnetism in two-dimensional materials.

基于TLE双行根数的航天器机动检测方法

由于不同功能的航天器承担的任务不尽相同、轨道亦不相同等原因,航天器不时需要变轨机动以确保完成任务.对于非合作航天器,其可能的变轨信息预先未知且难以预测,故需要准确快速判断航天器的变轨事件,以及时调整轨道探测策略.由于美国公布的双行根数具有来源稳定、更新频率快和容易获取等特点,本文结合航天器轨道动力学及变轨控制的特点,提出了基于TLE双行根数的航天器变轨机动检测方法,通过检测半长轴的变化量和相对距离最小值实现了在轨航天器轨道面内机动的检测.以METOP-A1和IRNSS 1G两个航天器在2019年6-9月的TLE根数为例,说明使用该方法开展机动检测的操作流程和步骤.同时大量仿真计算结果表明,该方法能够有效解决航天器在轨运行过程中面内机动时间和半长轴改变量的检测以及多次变轨识别的问题,检测精度与TLE根数自身精度及机动量大小相关.

Defects and morphology engineering for constructing V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S nanotube heterojunction arrays toward efficient bifunctional electrocatalyst for overall water splitting

The development of highly active,stable and inexpensive electrocatalysts for hydrogen production by defects and morphology engineering remains a great challenge.Herein,S vacancies-rich Ni_(3)S_(2)@Cu_(2)S nan-otube heterojunction arrays were in-situ grown on copper foam(V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF)for efficient electrocatalytic overall water splitting.With the merits of nanotube arrays and efficient electronic mod-ulation drived by the OD vacancy defect and 2D heterojunction defect,the resultant V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF electrocatalyst exhibits excellent electrocatalytic activity with a low overpotential of 47 mV for the hydrogen evolution reaction(HER)at 10 mA cm^(-2) current density,and 263 mV for the oxygen evolution reaction(OER)at 50 mA cm^(-2) current density,as well as a cell voltage of 1.48 V at 10 mA cm^(-2).Moreover,the nanotube heterojunction arrays endows V_(s)-Ni_(3)S_(2)@V_(s)-Cu_(2)S NHAs/CF with outstanding stability in long-term catalytic processes,as confirmed by the continuous chronopotentiom-etry tests at current densities of 10 mA cm^(-2) for 100 h.

Molecular-level proton acceptor boosts oxygen evolution catalysis to enable efficient industrial-scale water splitting

Industrial water splitting has long been suppressed by the sluggish kinetics of the oxygen evolution reaction(OER),which requires a catalyst to be efficient.Herein,we propose a molecular-level proton acceptor strategy to produce an efficient OER catalyst that can boost industrial-scale water splitting.Molecular-level phosphate(-PO_(4))group is introduced to modify the surface of PrBa_(0.5)Ca_(0.5)Co_(2)O_(5)+δ(PBCC).The achieved catalyst(PO_(4)-PBCC)exhibits significantly enhanced catalytic performance in alkaline media.Based on the X-ray absorption spectroscopy results and density functional theory(DFT)calculations,the PO_(4)on the surface,which is regarded as the Lewis base,is the key factor to overcome the kinetic limitation of the proton transfer process during the OER.The use of the catalyst in a membrane electrode assembly(MEA)is further evaluated for industrial-scale water splitting,and it only needs a low voltage of 1.66 V to achieve a large current density of 1 A cm^(-2).This work provides a new molecular-level strategy to develop highly efficient OER electrocatalysts for industrial applications.

The component-activity interrelationship of cobalt-based bifunctional electrocatalysts for overall water splitting:Strategies and performance

Cobalt-based electrocatalysts take advantage of potentially harmonizable microstructure and flexible coupling effects compared to commercial noble metal-based catalytic materials.However,conventional water electrolysis systems based on cobalt-based monofunctional hydrogen evolution reaction(HER)or oxygen evolution reaction(OER)catalysts have certain shortcomings in terms of resource utilization and universality.In contrast,cobalt-based bifunctional catalysts(CBCs)have attracted much attention in recent years for overall water splitting systems because of their practicality and reduced preparation cost of electrolyzer.This review aims to address the latest development in CBCs for total hydrolysis.The main modification strategies of CBCs are systematically classified in water electrolysis to provide an overview of how to regulate their morphology and electronic configuration.Then,the catalytic performance of CBCs in total-hydrolysis is summarized according to the types of cobalt-based phosphides,sulfides and oxides,and the mechanism of strengthened electrocatalytic ability is emphasized through combining experiments and theoretical calculations.Future efforts are finally suggested to focus on exploring the dynamic conversion of reaction intermediates and building near-industrial CBCs,designing advanced CBC materials through micro-modulation,and addressing commercial applications.

Defect engineering in transition-metal(Fe,Co,andNi)-based electrocatalysts for water splitting

Electrocatalytic water splitting seems to be an efficient strategy to deal with increasingly serious environmental problems and energy crises but still suffers from the lack of stable and efficient electrocatalysts.Designing practical electrocatalysts by introducing defect engineering,such as hybrid structure,surface vacancies,functional modification,and structural distortions,is proven to be a dependable solution for fabricating electrocatalysts with high catalytic activities,robust stability,and good practicability.This review is an overview of some relevant reports about the effects of defect engineering on the electrocatalytic water splitting performance of electrocatalysts.In detail,the types of defects,the preparation and characterization methods,and catalytic performances of electrocatalysts are presented,emphasizing the effects of the introduced defects on the electronic structures of electrocatalysts and the optimization of the intermediates'adsorption energy throughout the review.Finally,the existing challenges and personal perspectives of possible strategies for enhancing the catalytic performances of electrocatalysts are proposed.An in-depth understanding of the effects of defect engineering on the catalytic performance of electrocatalysts will light the way to design high-efficiency electrocatalysts for water splitting and other possible applications.

Sparse-view neutron CT 3D image reconstruction algorithm based on split Bregman method

As a complement to X-ray computed tomography(CT),neutron tomography has been extensively used in nuclear engineer-ing,materials science,cultural heritage,and industrial applications.Reconstruction of the attenuation matrix for neutron tomography with a traditional analytical algorithm requires hundreds of projection views in the range of 0°to 180°and typically takes several hours to complete.Such a low time-resolved resolution degrades the quality of neutron imaging.Decreasing the number of projection acquisitions is an important approach to improve the time resolution of images;however,this requires efficient reconstruction algorithms.Therefore,sparse-view reconstruction algorithms in neutron tomography need to be investigated.In this study,we investigated the three-dimensional reconstruction algorithm for sparse-view neu-tron CT scans.To enhance the reconstructed image quality of neutron CT,we propose an algorithm that uses OS-SART to reconstruct images and a split Bregman to solve for the total variation(SBTV).A comparative analysis of the performances of each reconstruction algorithm was performed using simulated and actual experimental data.According to the analyzed results,OS-SART-SBTV is superior to the other algorithms in terms of denoising,suppressing artifacts,and preserving detailed structural information of images.

Defect Engineering and Carbon Supporting to Achieve Ni‑Doped CoP_(3) with High Catalytic Activities for Overall Water Splitting

This work reports the use of defect engineering and carbon supporting to achieve metal-doped phosphides with high activities and stabilities for the hydrogen evolution reaction(HER)and the oxygen evolution reaction(OER)in alkaline media.Specifically,the nitrogen-doped carbon nanofiber-supported Ni-doped CoP_(3) with rich P defects(Pv·)on the carbon cloth(p-NiCoP/NCFs@CC)is synthesized through a plasma-assisted phosphorization method.The p-NiCoP/NCFs@CC is an efficient and stable catalyst for the HER and the OER.It only needs overpotentials of 107 and 306 mV to drive 100 mA cm^(-2) for the HER and the OER,respectively.Its catalytic activities are higher than those of other catalysts reported recently.The high activities of the p-NiCoP/NCFs@CC mainly arise from its peculiar structural features.The density functional theory calculation indicates that the Pv·richness,the Ni doping,and the carbon supporting can optimize the adsorption of the H atoms at the catalyst surface and promote the strong electronic couplings between the carbon nanofiber-supported p-NiCoP with the surface oxide layer formed during the OER process.This gives the p-NiCoP/NCFs@CC with the high activities for the HER and the OER.When used in alkaline water electrolyzers,the p-NiCoP/NCFs@CC shows the superior activity and excellent stability for overall water splitting.

Deactivation mechanism for water splitting:Recent advances

Hydrogen(H2)has been regarded as a promising alternative to fossil-fuel energy.Green H2 produced via water electrolysis(WE)powered by renewable energy could achieve a zero-carbon footprint.Considerable attention has been focused on developing highly active catalysts to facilitate the reaction kinetics and improve the energy efficiency of WE.However,the stability of the electrocatalysts hampers the commercial viability of WE.Few studies have elucidated the origin of catalyst degradation.In this review,we first discuss the WE mechanism,including anodic oxygen evolution reaction(OER)and cathodic hydrogen evolution reaction(HER).Then,we provide strategies used to enhance the stability of electrocatalysts.After that,the deactivation mechanisms of the typical commercialized HER and OER catalysts,including Pt,Ni,RuO_(2),and IrO_(2),are summarized.Finally,the influence of fluctuating energy on catalyst degradation is highlighted and in situ characterization methodologies for understanding the dynamic deactivation processes are described.

Thermochemical splitting of CO_(2) on perovskites for CO production: A review

Energy supply dominated by fossil energy has been and remains the main cause of carbon dioxide emissions,the major greenhouse gas leading to the current grave climate change challenges.Many technical pathways have been proposed to address the challenges.Carbon capture and utilization(CCU) represents one of the approaches and thermochemical CO_(2) splitting driven by thermal energy is a subset of the CCU,which converts the captured CO_(2) into CO and makes it possible to achieve closed-loop carbon recirculation.Redox-active catalysts are among the most critical components of the thermochemical splitting cycles and perovskites are regarded as the most promising catalysts.Here we review the latest advancements in thermochemical cycles based on perovskites,covering thermodynamic principles,material modifications,reaction kinetics,oxygen pressure control,circular strategies,and demonstrations to provide a comprehensive overview of the topical area.Thermochemical cycles based on such materials require the consideration of trade-off between cost and efficiency,which is related to actual material used,operation mode,oxygen removal,and heat recovery.Lots of efforts have been made towards improving reaction rates,conversion efficiency and cycling stability,materials related research has been lacking-a key aspect affecting the performance across all above aspects.Double perovskites and composite perovskites arise recently as a potentially promising addition to material candidates.For such materials,more effective oxygen removal would be needed to enhance the overall efficiency,for which thermochemical or electrochemical oxygen pumps could contribute to efficient oxygen removal as well as serve as means for inert gas regeneration.The integration of thermochemical CO_(2) splitting process with downstream fuel production and other processes could reduce costs and increase efficiency of the technology.This represents one of the directions for the future research.

Atomically dispersed Ni electrocatalyst for superior urea-assisted water splitting

Urea oxidation reaction(UOR) has been selected as substitution for oxygen evolution reaction ascribing to its low thermodynamic voltage as well as utilization of nickel as electrocatalyst.Herein,we report the formation of nickel single atoms(Ni-SAs) as exceptional bifunctional electrocatalyst toward UOR and hydrogen evolution reaction(HER) in urea-assisted water splitting.In UOR catalysis,Ni-SAs perform a superior catalytic performance than Ni-NP/NC and Pt/C ascribing to the formation of HOO-Ni-N_(4) structure evidenced by in-situ Raman spectroscopy,corresponding to a boosted mass activity by 175-fold at 1.4 V vs.RHE than Ni-NP/NC.Furthermore,Ni-SAs requires only 450 mV overpotential to obtain HER current density of 500 mA cm^(-2).136 mA cm^(-2) is achieved in urea-assisted water splitting at1.7 V for Ni-SAs,boosted by 5.7 times than Pt/C-IrO_(2) driven water splitting.

Self-derivation and reconstruction of silver nanoparticle reinforced cobalt-nickel bimetallic hydroxides through interface engineering for overall water splitting

Designing efficient and long-lasting non-metal electrocatalysts is an urgent task for addressing the issue of kinetic hysteresis in electrochemical oxidation reactions.The bimetallic hydroxides,catalyzing the oxygen evolution reaction(OER),have significant research potential because hydroxide reconstruction to generate an active phase is a remarkable advantage.Herein,the complete reconstruction of ultrathin CoNi(OH)_(2) nanosheets was achieved by embedding Ag nanoparticles into the hydroxide to induce a spontaneous redox reaction(SRR),forming heterojunction Ag@CoNi(OH)_(2) for bifunctional hydrolysis.Theoretical calculations and in situ Raman and ex situ characterizations revealed that the inductive effect of the Ag cation redistributed the charge to promote phase transformation to highly activate Ag-modified hydroxides.The Co-Ni dual sites in Co/NiOOH serve as novel active sites for optimizing the intermediates,thereby weakening the barrier formed by OOH^*.Ag@CoNi(OH)_(2) required a potential of 1.55 V to drive water splitting at a current density of 10 mA cm^(-2),with nearly 98.6% Faraday efficiency.Through ion induction and triggering of electron regulation in the OER via the synergistic action of the heterogeneous interface and surface reconstruction,this strategic design can overcome the limited capacity of bimetallic hydroxides and bridge the gap between the basic theory and industrialization of water decomposition.