Transition metal carbides,known as MXenes,particularly Ti_(3)C_(2)T_(x),have been extensively explored as promising materials for electrochemical reactions.However,transition metal carbonitride MXenes with high nitrog...Transition metal carbides,known as MXenes,particularly Ti_(3)C_(2)T_(x),have been extensively explored as promising materials for electrochemical reactions.However,transition metal carbonitride MXenes with high nitrogen content for electrochemical reactions are rarely reported.In this work,transition metal carbonitride MXenes incorporated with Pt-based electrocatalysts,ranging from single atoms to sub-nanometer dimensions,are explored for hydrogen evolution reaction(HER).The fabricated Pt clusters/MXene catalyst exhibits superior HER performance compared to the single-atom-incorporated MXene and commercial Pt/C catalyst in both acidic and alkaline electrolytes.The optimized sample shows low overpotentials of 28,65,and 154 mV at a current densities of 10,100,and 500 m A cm^(-2),a small Tafel slope of 29 m V dec^(-1),a high mass activity of 1203 mA mgPt^(-1)and an excellent turnover frequency of 6.1 s^(-1)in the acidic electrolyte.Density functional theory calculations indicate that this high performance can be attributed to the enhanced active sites,increased surface functional groups,faster charge transfer dynamics,and stronger electronic interaction between Pt and MXene,resulting in optimized hydrogen absorption/desorption toward better HER.This work demonstrates that MXenes with a high content of nitrogen may be promising candidates for various catalytic reactions by incorporating single atoms or clusters.展开更多
Correction to:Nano-Micro Letters(2025)17:123 https://doi.org/10.1007/s40820-025-01654-y Following publication of the original article[1],the authors reported that Dr.Mohamed Bououdina’s affiliation needed to be corre...Correction to:Nano-Micro Letters(2025)17:123 https://doi.org/10.1007/s40820-025-01654-y Following publication of the original article[1],the authors reported that Dr.Mohamed Bououdina’s affiliation needed to be corrected from 1 to 2.The correct author affiliation has been provided in this Correction and the original article[1]has been corrected.展开更多
针对无规律变化的光源光束点和手动调束费时费力问题,本文实现了基于实验物理及工业控制系统(Experimental Physics and Industrial Control System,EPICS)的同步辐射光束线智能优化调束。该系统基于差分进化算法,建立光束线智能优化模...针对无规律变化的光源光束点和手动调束费时费力问题,本文实现了基于实验物理及工业控制系统(Experimental Physics and Industrial Control System,EPICS)的同步辐射光束线智能优化调束。该系统基于差分进化算法,建立光束线智能优化模型,应用LabVIEW程序实现调束过程的自动优化。系统可以自由选择待优化的电机及其搜索范围,设置算法参数,跟踪进化进程,通过CaLab接口模块与光束线EPICS软件平台进行通信,控制电机运动。对该系统在上海光源衍射线站进行了在线测试,首次成功地在EPICS控制平台上实现了光束线的智能调束优化。测试结果表明:该智能调束系统能够较快地收敛于最优解,收敛时间大约30 min,较手动优化效率提高一个数量级以上。展开更多
Significant optical engineering advances at the University of Arizona are being made for design, fabrication, and construction of next generation astronomical telescopes. This summary review paper focuses on the techn...Significant optical engineering advances at the University of Arizona are being made for design, fabrication, and construction of next generation astronomical telescopes. This summary review paper focuses on the technological advances in three key areas. First is the optical fabrication technique used for constructing next-generation telescope mirrors. Advances in ground-based telescope control and instrumentation comprise the second area of development. This includes active alignment of the laser truss-based Large Binocular Telescope(LBT) prime focus camera, the new MOBIUS modular cross-dispersion spectroscopy unit used at the prime focal plane of the LBT, and topological pupil segment optimization. Lastly, future space telescope concepts and enabling technologies are discussed. Among these, the Nautilus space observatory requires challenging alignment of segmented multi-order diffractive elements. The OASIS terahertz space telescope presents unique challenges for characterizing the inflatable primary mirror, and the Hyperion space telescope pushes the limits of high spectral resolution, far-UV spectroscopy. The Coronagraphic Debris and Exoplanet Exploring Pioneer(CDEEP) is a Small Satellite(Small Sat) mission concept for high-contrast imaging of circumstellar disks and exoplanets using vector vortex coronagraph. These advances in optical engineering technologies will help mankind to probe, explore, and understand the scientific beauty of our universe.展开更多
Selective coupling of methyl radicals to produce C_(2) species(C2H4 and C2H6)is a key challenge for oxidative coupling of methane(OCM).In traditional OCM reaction systems,homogeneous transformation of methyl radicals ...Selective coupling of methyl radicals to produce C_(2) species(C2H4 and C2H6)is a key challenge for oxidative coupling of methane(OCM).In traditional OCM reaction systems,homogeneous transformation of methyl radicals in O_(2)‐containing gases are uncontrollable,resulting in limited C_(2) selectivity and yield.Herein,we demonstrate that methyl radicals generated by La_(2)O_(3)at low reaction temperature can selectively couple on the surface of 5 wt%Na2WO4/SiO_(2).The controllable surface coupling against overoxidation barely changes the activity of La_(2)O_(3)but boosts the C_(2)selectivity by three times and achieves a C_(2)yield as high as 10.9%at bed temperature of only 570℃.Structure‐property studies suggest that Na_(2)WO_(4) nanoclusters are the active sites for methyl radical coupling.The strong CH_(3)·affinity of these sites can even endow some methane combustion catalysts with OCM activity.The findings of the surface coupling of methyl radicals open a new direction to develop OCM catalyst.The bifunctional OCM catalyst system,which composes of a methane activation center and a CH_(3)·coupling center,may deliver promising OCM performance at reaction temperatures below the ignition temperature of C2H6 and C2H4(~600℃)and is therefore more controllable,safer,and certainly more attractive as an actual process.展开更多
In this article, we present the promise of a new method generating double electron pulses in picosecondscale pulse length and tunable interpulse spacing at several picoseconds. This has witnessed an impressive potenti...In this article, we present the promise of a new method generating double electron pulses in picosecondscale pulse length and tunable interpulse spacing at several picoseconds. This has witnessed an impressive potential of application in pump–probe techniques, two-color X-ray free electron laser, high-gradient witness bunch acceleration in a plasma, etc. Three-dimensional simulations are carried out to analyze the dynamic of the electron beam in a linear accelerator. Comparisons are made between the new method and existing ways.展开更多
The oxygen evolution reaction(OER)activity of single-atom catalysts(SACs)is closely related to the coordination environment of the active site.Oxygencoordinated atomic metal species bring about unique features beyond ...The oxygen evolution reaction(OER)activity of single-atom catalysts(SACs)is closely related to the coordination environment of the active site.Oxygencoordinated atomic metal species bring about unique features beyond nitrogen-coordinated atomic metal species due to the fact that the M-O bond is weaker than the M-N bond.Herein,a series of metal-oxygen-carbon structured low-nucleus clusters(LNCs)are successfully anchored on the surface of multiwalled carbon nanotubes(M-MWCNTs,M=Ni,Co,or Fe)through a foolproof low-temperature gas transfer(300℃)method without any further treatment.The morphology and coordination configuration of the LNCs at the atomic level were confirmed by comprehensive characterizations.The synthetic Ni-MWCNTs electrocatalyst features excellent OER activity and stability under alkaline conditions,transcending the performances of Co-MWCNTs,Fe-MWCNTs and RuO_(2).Density functional theory calculations reveal that the moderate oxidation of low-nucleus Ni clusters changes the unoccupied orbital of Ni atoms,thereby lowering the energy barrier of the OER rate-limiting step and making the OER process more energy-efficient.This study demonstrates a novel versatile platform for large-scale manufacturing of oxygen-coordinated LNC catalysts.展开更多
The commercialization of nickel-rich LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) has been hindered by its continuous loss of practical capacity and reduction in average working voltage.To address these issues,surface modi...The commercialization of nickel-rich LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) has been hindered by its continuous loss of practical capacity and reduction in average working voltage.To address these issues,surface modification has been well-recognized as an effective strategy.Different from the coatings reported in literature to date,in this work,we for the first time report a sulfide coating,amorphous Li_(2)S via atomic layer deposition (ALD).Our study revealed that the conformal nano-Li_(2)S coating shows exceptional protection over the NMC811 cathodes,accounting for the dramatically boosted capacity retention from~11.6%to~71%and the evidently mitigated voltage reduction from 0.39 to 0.18 V after 500 charge–discharge cycles.In addition,the Li_(2)S coating remarkably improved the rate capability of the NMC811 cathode.Our investigation further revealed that all these beneficial effects of the ALD-deposited nano-Li_(2)S coating lie in the following aspects:(i) maintain the mechanical integrity of the NMC811 electrode:(ii) stabilize the NMC electrode/electrolyte interface:and (iii) suppress the irreversible phase transition of NMC structure.Particularly,this study also has revealed that the nano-Li_(2)S coating has played some unique role not associated with traditional non-sulfide coatings such as oxides.In this regard,we disclosed that the Li_(2)S layer has reacted with the released O_(2) from the NMC lattices,and thereby has dramatically mitigated electrolyte oxidation and electrode corrosion.Thus,this study is significant and has demonstrated that sulfides may be an important class of coating materials to tackle the issues of NMCs and other layered cathodes in lithium batteries.展开更多
Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored ...Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored in porous nanomaterials is still challenging.Here,through the template-free S-assisted pyrolysis of low-cost Fe-salts with melamine(MA),porous alveolate Fe/g-C3N4 catalysts with high-density(Fe loading up to 17.7 wt%)and increased USCAD Fe sites were synthesized.The presence of a certain amount of S species in the Fe-salts/MA system plays an important role in the formation of USCAD S-Fe-salt/CN catalysts;the S species act as a"sacrificial carrier"to increase the dispersion of Fe species through Fe-S coordination and generate porous alveolate structure by escaping in the form of SO2 during pyrolysis.The S-Fe-salt/CN catalysts exhibit greatly promoted activity and reusability for degrading various organic pollutants in advanced oxidation processes compared to the corresponding Fe-salt/CN catalysts,due to the promoted accessibility of USCAD Fe sites by the porous alveolate structure.This S-assisted method exhibits good feasibility in a large variety of S species(thiourea,S powder,and NH4SCN)and Fe salts,providing a new avenue for the low-cost and large-scale synthesis of high-density USCAD metal/g-C3N4 catalysts.展开更多
Two lowly fused non-fullerene acceptors(NFAs)with isomeric structures,named as BTP-out-4F and BTP-in-4F,were developed by tailoring the fused 7-ring central core of Y6 into a lowly fused 5-ring linked with two octylox...Two lowly fused non-fullerene acceptors(NFAs)with isomeric structures,named as BTP-out-4F and BTP-in-4F,were developed by tailoring the fused 7-ring central core of Y6 into a lowly fused 5-ring linked with two octyloxythiophene bridges.BTP-out-4F with octyloxy side chains away from the central core exhibited large steric hindrance that restrained the rotational freedom between the thiophene bridge and end group but maintained free rotation between the central core and the thiophene bridge.In contrast,BTP-in-4F with octyloxy side chains close to the central core had much lower rotation freedom due to the non-covalent S⋯O interactions locked the central core,thiophene bridge and end group simultaneously,making BTP-in-4F have higher molecular crystallinity.On the other hand,the optical properties,energy levels and the blend morphology properties were significantly influenced,leading to distinctive photovoltaic performances.BTP-out-4F formed favorable energy level alignment and morphology when matching with PBDB-T donor,thus its device realized a much higher PCE of 13.32%,which was over 13 times than that of BTP-in-4F based device(PCE=0.97%).展开更多
Regulating the selectivity toward a target hydrocarbon product is still the focus of CO_(2)electroreduction.Here,we discover that the original surface Cu species in Cu gas-diffusion electrodes plays a more important r...Regulating the selectivity toward a target hydrocarbon product is still the focus of CO_(2)electroreduction.Here,we discover that the original surface Cu species in Cu gas-diffusion electrodes plays a more important role than the surface roughness,local pH,and facet in governing the selectivity toward C_(1)or C_(2)hydrocarbons.The selectivity toward C_(2)H_(4) progressively increases,while CH_(4) decreases steadily upon lowering the Cu oxidation species fraction.At a relatively low electrodeposition voltage of 1.5 V,the Cu gas-diffusion electrode with the highest Cu^(δ+)/Cu^(0)ratio favors the pathways of∗CO hydrogenation to form CH_(4) with maximum Faradaic efficiency of 65.4%and partial current density of 228 mA cm^(−2)at−0.83 V vs RHE.At 2.0 V,the Cu gas-diffusion electrode with the lowest Cu^(δ+)/Cu^(0)ratio prefers C-C coupling to form C_(2)+products with Faradaic efficiency topping 80.1%at−0.75 V vs RHE,where the Faradaic efficiency of C_(2)H_(4) accounts for 46.4%and the partial current density of C_(2)H_(4) achieves 279 mA cm^(−2).This work demonstrates that the selectivity from CH_(4) to C_(2)H_(4) is switchable by tuning surface Cu species composition of Cu gas-diffusion electrodes.展开更多
Strain gradient is a normal phenomenon around a heterostructural interface in ultrathin film,and it is important to determine its effect on magnetic interactions to understand interfacial coupling.In this work,ultrath...Strain gradient is a normal phenomenon around a heterostructural interface in ultrathin film,and it is important to determine its effect on magnetic interactions to understand interfacial coupling.In this work,ultrathin Pr_(0.67)Sr_(0.33)MnO_(3)(PSMO)films on different substrates are studied.For PSMO film under different in-plane strain conditions,the saturated magnetization and Curie temperature can be qualitatively explained by double-exchange interaction and the Jahn-Teller distortion.However,the difference in the saturated magnetization with zero field cooling and 5 T field cooling is proportional to the strain gradient.Strain-gradient-induced structural disorder is proposed to enhance phonon-electron antiferromagnetic interactions and the corresponding antiferromagnetic-to-ferromagnetic phase transition via a strong magnetic field during the field cooling process.A non-monotonous structural transition of the MnO_(6) octahedral rotation can enlarge the strain gradient in PSMO film on a SrTiO_(3) substrate.This work demonstrates the existence of the flexomagnetic effect in ultrathin manganite film,which should be applicable to other complex oxide systems.展开更多
Molybdenum oxide/sulfide materials are extensively evaluated as high-capacity anode candidates for lithium ion batteries.However,they suffer from rapid capacity decay and poor kinetics.Herein,we report on synergistic ...Molybdenum oxide/sulfide materials are extensively evaluated as high-capacity anode candidates for lithium ion batteries.However,they suffer from rapid capacity decay and poor kinetics.Herein,we report on synergistic effect from structurally integrated coaxial CNTs@MoS_(2)/MoO_(2) composite material on lithium storage,in which MoS_(2)/MoO_(2) nanosheets are conformally decorated on carbon nanotubes(CNTs).In-situ synchrotron X-ray diffraction measurement is performed to elucidate synergistic effect among three MoS_(2),MoO_(2) and CNTs components for lithium storage.Reaction mechanism exploration reveals that the MoO_(2) component undergoes reversible Li^(+)intercalation via forming a stable Li_(0.98) MoO_(2) phase over a voltage range of 3.0 to 0.01 V vs.Li^(+)/Li,without experiencing the conversion reaction into metallic Mo,which contributes to long-term stability during charge/discharge cycles.Meanwhile,lithium storage of MoS_(2) is through lithium and sulfur reversible reaction after the initial conversion reaction of lithiated MoS_(2) forming Li_(2)S and Mo.The CNTs component enhances electronic conductivity and structural stability by minimizing volume change and reaction strains in the CNTs@MoS_(2)/MoO_(2) composite anode.A desired 68.2%capacity retention upon 2000 cycles at 10 A/g has been demonstrated for the CNTs@MoS_(2)/MoO_(2) anode,revealing prominent reaction kinetics and structural stability for fast and stable lithium storage,superior to various Mo-based anode materials previously reported.The findings from this study,with the unique insight into the role of structural integrity in combining MoS_(2)/MoO_(2) materials with the CNTs substrate,offers a strategy for designing composite anode materials for superior lithium storage performance.展开更多
Polarimetry encompasses a collection of optical techniques broadly used in a variety of fields.Nowadays,such techniques have provided their suitability in the biomedical field through the study of the polarimetric res...Polarimetry encompasses a collection of optical techniques broadly used in a variety of fields.Nowadays,such techniques have provided their suitability in the biomedical field through the study of the polarimetric response of biological samples(retardance,dichroism and depolarization)by measuring certain polarimetric observables.One of these features,depolarization,is mainly produced by scattering on samples,which is a predominant efiect in turbid media as biological tissues.In turn,retardance and dichroic efiects are produced by tissue anisotropies and can lead to depolarization too.Since depolarization is a predominant efiect in tissue samples,we focus on studying difierent depolarization metrics for biomedical applications.We report the suitability of a set of depolarizing observables,the indices of polarimetric purity(IPPs),for biological tissue inspection.We review some results where we demonstrate that IPPs lead to better performance than the depolarization index,which is a well-established and commonly used depolarization observable in the literature.We also provide how IPPs are able to significantly enhance contrast between difierent tissue structures and even to reveal structures hidden by using standard intensity images.Finally,we also explore the classificatory potential of IPPs and other depolarizing observables for the discrimination of difierent tissues obtained from ex vivo chicken samples(muscle,tendon,myotendinous junction and bone),reaching accurate models for tissue classification.展开更多
Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion batteries.The low-polysulfide-solubility ...Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion batteries.The low-polysulfide-solubility feature of some carbonate solvents also makes them very promising for overcoming the shuttle effects of LSBs.However,regular sulfur electrodes experience undesired electrochemical mechanisms in carbonate electrolytes due to side reactions.In this study,we report a catalytic redox mechanism of sulfur in propylene carbonate(PC)electrolyte based on a compari-son study.The catalytic mechanism is characterized by the interactions between polysulfides and dual N/O functional groups on the host carbon,which largely prevents side reactions between polysulfides and the carbonate electrolyte.Such a mechanism coupled with the low-polysulfide-solubility feature leads to stable cycling of LSBs in PC electrolyte.Favorable dual N/O functional groups are identified via a density functional theory study.This work provides an alternative route for enabling LSBs in carbonate electrolytes.展开更多
Optics with high-precision height and slope are increasingly desired in numerous industrial fields.For instance,Kirkpatrick-Baez(KB)mirrors play an important role in synchrotron X-ray applications.A KB system is compo...Optics with high-precision height and slope are increasingly desired in numerous industrial fields.For instance,Kirkpatrick-Baez(KB)mirrors play an important role in synchrotron X-ray applications.A KB system is composed of two aspherical,grazing-incidence mirrors used to focus an X-ray beam.The fabrication of KB mirrors is challenging due to the aspherical departure of the mirror surfaces from base geometries and the high-quality requirements for slope and height residuals.In this paper,we present the process of manufacturing an elliptical cylinder KB mirror using our in-house-developed ion beam figuring(IBF)and metrology technologies.First,the key aspects of figuring and finishing processes with IBF are illustrated in detail.The effect of positioning error on the convergence of the residual slope error is highlighted and compensated.Finally,inspection and cross-validation using different metrology instruments are performed and used as the final validation of the mirror.Results confirm that relative to the requested off-axis ellipse,the mirror has achieved 0.15-μrad root mean square(RMS)and 0.36-nm RMS residual slope and height errors,respectively,while maintaining the initial 0.3-nm RMS microroughness.展开更多
Biochar pores in the micrometer range(1-100μm)derive from cellular structures of the plant biomass subjected to pyrolysis or can be the result of mechanical processing,such as pelleting.In this study,synchrotron X-ra...Biochar pores in the micrometer range(1-100μm)derive from cellular structures of the plant biomass subjected to pyrolysis or can be the result of mechanical processing,such as pelleting.In this study,synchrotron X-ray microtomography was used to investigate the internal pore structure of softwood pellet biochar produced by slow pyrolysis at 550 and 700°C.The microtomographic data sets consisted of 2025 images of 2560×2560 voxels with a voxel side length of 0.87μm.The three-dimensional reconstructions revealed that pelleting and pyrolysis significantly altered the pore structures of the wood feedstock,creating a network of connected pores between fragments that resembled the wood morphology.While higher pyrolysis temperature increased the specific surface area(as determined by BET nitrogen adsorption),it did not affect the total observed porosity.Multifractal analysis was applied to assess the characteristics of the frequency distribution of pores along each of the three dimensions of reconstructed images of five softwood pellet biochar samples.The resulting singular-ity and Rényi spectra(generalized dimensions)indicated that the distribution of porosity had monofractal scaling behavior,was homogeneous within the analyzed volumes and consistent between replicate samples.Moreover,the pore distributions were isotropic(direction-independent),which is in strong contrast with the anisotropic pore structure of wood.As pores at the scale analyzed in this study are relevant,for example,for the supply of plant accessible water and habitable space for microorganisms,our findings combined with the ability to reproduce biochar with such pore distribution offer substantial advantages in various biochar applications.展开更多
Integrated rocksalt-polyanion cathodes(DRXPS)are promising candidates for next-generation lithium-ion battery cathode materials that combine high energy density,stable cycling performance,and reduced reliance on Co an...Integrated rocksalt-polyanion cathodes(DRXPS)are promising candidates for next-generation lithium-ion battery cathode materials that combine high energy density,stable cycling performance,and reduced reliance on Co and Ni.In this work,we investigated Li_(3)Mn_(1.6)P_(0.4)O_(5.4)F_(0.6),a new DRXPS cathode with fluoride incorporation.A pure spinel phase was formed and a discharge capacity retention of 84%was achieved after 200 cycles between 1.5 and 4.8 V versus Li/Li^(+).In comparison,the similarly synthesized Li_(3)Mn_(1.6)Nb_(0.4)O_(5.4)F_(0.6),in which all P^(5+)was substituted by Nb^(5+)while maintaining the same stoichiometry for all other elements,crystallized in a disordered rocksalt structure,and exhibited inferior capacity retention and rate capability than the P^(5+)counterpart.Our findings expand the compositional space of DRXPS to include F^(−),justify the viability of integrating polyanion groups in rocksalt-type cathodes,and highlight the superiority of P^(5+)as a cation charge compensator compared to the commonly used Nb^(5+).This work thereby advances the design of robust,high-performance cathode materials for sustainable batteries.展开更多
基金the final support of ARC DP220103045the startup support of KFUPMPrince Sultan University for their support。
文摘Transition metal carbides,known as MXenes,particularly Ti_(3)C_(2)T_(x),have been extensively explored as promising materials for electrochemical reactions.However,transition metal carbonitride MXenes with high nitrogen content for electrochemical reactions are rarely reported.In this work,transition metal carbonitride MXenes incorporated with Pt-based electrocatalysts,ranging from single atoms to sub-nanometer dimensions,are explored for hydrogen evolution reaction(HER).The fabricated Pt clusters/MXene catalyst exhibits superior HER performance compared to the single-atom-incorporated MXene and commercial Pt/C catalyst in both acidic and alkaline electrolytes.The optimized sample shows low overpotentials of 28,65,and 154 mV at a current densities of 10,100,and 500 m A cm^(-2),a small Tafel slope of 29 m V dec^(-1),a high mass activity of 1203 mA mgPt^(-1)and an excellent turnover frequency of 6.1 s^(-1)in the acidic electrolyte.Density functional theory calculations indicate that this high performance can be attributed to the enhanced active sites,increased surface functional groups,faster charge transfer dynamics,and stronger electronic interaction between Pt and MXene,resulting in optimized hydrogen absorption/desorption toward better HER.This work demonstrates that MXenes with a high content of nitrogen may be promising candidates for various catalytic reactions by incorporating single atoms or clusters.
文摘Correction to:Nano-Micro Letters(2025)17:123 https://doi.org/10.1007/s40820-025-01654-y Following publication of the original article[1],the authors reported that Dr.Mohamed Bououdina’s affiliation needed to be corrected from 1 to 2.The correct author affiliation has been provided in this Correction and the original article[1]has been corrected.
文摘针对无规律变化的光源光束点和手动调束费时费力问题,本文实现了基于实验物理及工业控制系统(Experimental Physics and Industrial Control System,EPICS)的同步辐射光束线智能优化调束。该系统基于差分进化算法,建立光束线智能优化模型,应用LabVIEW程序实现调束过程的自动优化。系统可以自由选择待优化的电机及其搜索范围,设置算法参数,跟踪进化进程,通过CaLab接口模块与光束线EPICS软件平台进行通信,控制电机运动。对该系统在上海光源衍射线站进行了在线测试,首次成功地在EPICS控制平台上实现了光束线的智能调束优化。测试结果表明:该智能调束系统能够较快地收敛于最优解,收敛时间大约30 min,较手动优化效率提高一个数量级以上。
基金the Gordon and Betty Moore Foundation for their financial support of the development of the MODElens and its enabling alignment technologiesthe II-VI Foundation Block-Gift,Technology Research Initiative Fund Optics/Imaging Program。
文摘Significant optical engineering advances at the University of Arizona are being made for design, fabrication, and construction of next generation astronomical telescopes. This summary review paper focuses on the technological advances in three key areas. First is the optical fabrication technique used for constructing next-generation telescope mirrors. Advances in ground-based telescope control and instrumentation comprise the second area of development. This includes active alignment of the laser truss-based Large Binocular Telescope(LBT) prime focus camera, the new MOBIUS modular cross-dispersion spectroscopy unit used at the prime focal plane of the LBT, and topological pupil segment optimization. Lastly, future space telescope concepts and enabling technologies are discussed. Among these, the Nautilus space observatory requires challenging alignment of segmented multi-order diffractive elements. The OASIS terahertz space telescope presents unique challenges for characterizing the inflatable primary mirror, and the Hyperion space telescope pushes the limits of high spectral resolution, far-UV spectroscopy. The Coronagraphic Debris and Exoplanet Exploring Pioneer(CDEEP) is a Small Satellite(Small Sat) mission concept for high-contrast imaging of circumstellar disks and exoplanets using vector vortex coronagraph. These advances in optical engineering technologies will help mankind to probe, explore, and understand the scientific beauty of our universe.
文摘Selective coupling of methyl radicals to produce C_(2) species(C2H4 and C2H6)is a key challenge for oxidative coupling of methane(OCM).In traditional OCM reaction systems,homogeneous transformation of methyl radicals in O_(2)‐containing gases are uncontrollable,resulting in limited C_(2) selectivity and yield.Herein,we demonstrate that methyl radicals generated by La_(2)O_(3)at low reaction temperature can selectively couple on the surface of 5 wt%Na2WO4/SiO_(2).The controllable surface coupling against overoxidation barely changes the activity of La_(2)O_(3)but boosts the C_(2)selectivity by three times and achieves a C_(2)yield as high as 10.9%at bed temperature of only 570℃.Structure‐property studies suggest that Na_(2)WO_(4) nanoclusters are the active sites for methyl radical coupling.The strong CH_(3)·affinity of these sites can even endow some methane combustion catalysts with OCM activity.The findings of the surface coupling of methyl radicals open a new direction to develop OCM catalyst.The bifunctional OCM catalyst system,which composes of a methane activation center and a CH_(3)·coupling center,may deliver promising OCM performance at reaction temperatures below the ignition temperature of C2H6 and C2H4(~600℃)and is therefore more controllable,safer,and certainly more attractive as an actual process.
基金partially supported by the Major State Basic Research Development Program of China(No.2011CB808300)the National Natural Science Foundation of China(Nos.11175240,11205234 and 11322550)
文摘In this article, we present the promise of a new method generating double electron pulses in picosecondscale pulse length and tunable interpulse spacing at several picoseconds. This has witnessed an impressive potential of application in pump–probe techniques, two-color X-ray free electron laser, high-gradient witness bunch acceleration in a plasma, etc. Three-dimensional simulations are carried out to analyze the dynamic of the electron beam in a linear accelerator. Comparisons are made between the new method and existing ways.
基金Leading Innovative and Entrepreneur Team Introduction Program of Zhejiang,Grant/Award Number:2019R01006National Key R&D Program of China,Grant/Award Number:2018YFB0104300。
文摘The oxygen evolution reaction(OER)activity of single-atom catalysts(SACs)is closely related to the coordination environment of the active site.Oxygencoordinated atomic metal species bring about unique features beyond nitrogen-coordinated atomic metal species due to the fact that the M-O bond is weaker than the M-N bond.Herein,a series of metal-oxygen-carbon structured low-nucleus clusters(LNCs)are successfully anchored on the surface of multiwalled carbon nanotubes(M-MWCNTs,M=Ni,Co,or Fe)through a foolproof low-temperature gas transfer(300℃)method without any further treatment.The morphology and coordination configuration of the LNCs at the atomic level were confirmed by comprehensive characterizations.The synthetic Ni-MWCNTs electrocatalyst features excellent OER activity and stability under alkaline conditions,transcending the performances of Co-MWCNTs,Fe-MWCNTs and RuO_(2).Density functional theory calculations reveal that the moderate oxidation of low-nucleus Ni clusters changes the unoccupied orbital of Ni atoms,thereby lowering the energy barrier of the OER rate-limiting step and making the OER process more energy-efficient.This study demonstrates a novel versatile platform for large-scale manufacturing of oxygen-coordinated LNC catalysts.
基金support from the Center for Advanced Surface Engineering, under the National Science Foundation Grant No. OIA-1457888the Arkansas EPSCoR Program, ASSET Ⅲ. X. M+1 种基金the financial support from the University of Arkansas, Fayetteville, AR, USAfunded by the U.S. Department of Energy (DOE), Vehicle Technologies Office。
文摘The commercialization of nickel-rich LiNi_(0.8)Mn_(0.1)Co_(0.1)O_(2)(NMC811) has been hindered by its continuous loss of practical capacity and reduction in average working voltage.To address these issues,surface modification has been well-recognized as an effective strategy.Different from the coatings reported in literature to date,in this work,we for the first time report a sulfide coating,amorphous Li_(2)S via atomic layer deposition (ALD).Our study revealed that the conformal nano-Li_(2)S coating shows exceptional protection over the NMC811 cathodes,accounting for the dramatically boosted capacity retention from~11.6%to~71%and the evidently mitigated voltage reduction from 0.39 to 0.18 V after 500 charge–discharge cycles.In addition,the Li_(2)S coating remarkably improved the rate capability of the NMC811 cathode.Our investigation further revealed that all these beneficial effects of the ALD-deposited nano-Li_(2)S coating lie in the following aspects:(i) maintain the mechanical integrity of the NMC811 electrode:(ii) stabilize the NMC electrode/electrolyte interface:and (iii) suppress the irreversible phase transition of NMC structure.Particularly,this study also has revealed that the nano-Li_(2)S coating has played some unique role not associated with traditional non-sulfide coatings such as oxides.In this regard,we disclosed that the Li_(2)S layer has reacted with the released O_(2) from the NMC lattices,and thereby has dramatically mitigated electrolyte oxidation and electrode corrosion.Thus,this study is significant and has demonstrated that sulfides may be an important class of coating materials to tackle the issues of NMCs and other layered cathodes in lithium batteries.
文摘Heterogeneous catalysts with ultra-small clusters and atomically dispersed(USCAD)active sites have gained increasing attention in recent years.However,developing USCAD catalysts with high-density metal sites anchored in porous nanomaterials is still challenging.Here,through the template-free S-assisted pyrolysis of low-cost Fe-salts with melamine(MA),porous alveolate Fe/g-C3N4 catalysts with high-density(Fe loading up to 17.7 wt%)and increased USCAD Fe sites were synthesized.The presence of a certain amount of S species in the Fe-salts/MA system plays an important role in the formation of USCAD S-Fe-salt/CN catalysts;the S species act as a"sacrificial carrier"to increase the dispersion of Fe species through Fe-S coordination and generate porous alveolate structure by escaping in the form of SO2 during pyrolysis.The S-Fe-salt/CN catalysts exhibit greatly promoted activity and reusability for degrading various organic pollutants in advanced oxidation processes compared to the corresponding Fe-salt/CN catalysts,due to the promoted accessibility of USCAD Fe sites by the porous alveolate structure.This S-assisted method exhibits good feasibility in a large variety of S species(thiourea,S powder,and NH4SCN)and Fe salts,providing a new avenue for the low-cost and large-scale synthesis of high-density USCAD metal/g-C3N4 catalysts.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.21825502,22075190,21905185 and 22105135)Special funds for local science and technology development guided by the central government(No.2020ZYD004)+1 种基金the Foundation of State Key Laboratory of Polymer Materials Engineering(No.SKLPME 2017-2-04)the Fundamental Research Funds for the Central Universities.
文摘Two lowly fused non-fullerene acceptors(NFAs)with isomeric structures,named as BTP-out-4F and BTP-in-4F,were developed by tailoring the fused 7-ring central core of Y6 into a lowly fused 5-ring linked with two octyloxythiophene bridges.BTP-out-4F with octyloxy side chains away from the central core exhibited large steric hindrance that restrained the rotational freedom between the thiophene bridge and end group but maintained free rotation between the central core and the thiophene bridge.In contrast,BTP-in-4F with octyloxy side chains close to the central core had much lower rotation freedom due to the non-covalent S⋯O interactions locked the central core,thiophene bridge and end group simultaneously,making BTP-in-4F have higher molecular crystallinity.On the other hand,the optical properties,energy levels and the blend morphology properties were significantly influenced,leading to distinctive photovoltaic performances.BTP-out-4F formed favorable energy level alignment and morphology when matching with PBDB-T donor,thus its device realized a much higher PCE of 13.32%,which was over 13 times than that of BTP-in-4F based device(PCE=0.97%).
基金partially financially supported by NSF CBET-2033343.J.Z.thanks the support from National Natural Science Foundation of China(52172293,51772072,and 51672065)the Fundamental Research Funds for the Central Universities(JZ2021HGQB0282 and PA2021GDSK0088)+3 种基金financial support from the Key R&D Projects of Anhui Province(202104b11020016)the 111 Project(B18018)the National Synchrotron Light Source II,a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No.DE-SC0012704the use of facilities within the Eyring Materials Center at Arizona State University supported in part by NNCI-ECCS-1542160.
文摘Regulating the selectivity toward a target hydrocarbon product is still the focus of CO_(2)electroreduction.Here,we discover that the original surface Cu species in Cu gas-diffusion electrodes plays a more important role than the surface roughness,local pH,and facet in governing the selectivity toward C_(1)or C_(2)hydrocarbons.The selectivity toward C_(2)H_(4) progressively increases,while CH_(4) decreases steadily upon lowering the Cu oxidation species fraction.At a relatively low electrodeposition voltage of 1.5 V,the Cu gas-diffusion electrode with the highest Cu^(δ+)/Cu^(0)ratio favors the pathways of∗CO hydrogenation to form CH_(4) with maximum Faradaic efficiency of 65.4%and partial current density of 228 mA cm^(−2)at−0.83 V vs RHE.At 2.0 V,the Cu gas-diffusion electrode with the lowest Cu^(δ+)/Cu^(0)ratio prefers C-C coupling to form C_(2)+products with Faradaic efficiency topping 80.1%at−0.75 V vs RHE,where the Faradaic efficiency of C_(2)H_(4) accounts for 46.4%and the partial current density of C_(2)H_(4) achieves 279 mA cm^(−2).This work demonstrates that the selectivity from CH_(4) to C_(2)H_(4) is switchable by tuning surface Cu species composition of Cu gas-diffusion electrodes.
基金supported by the Natural Science Foundation of Guangdong Province of China(2023A1515010882)the Large Scientific Facility Open Subject of Songshan Lake,Dongguan,Guangdong Province of China(KFKT2022B06)+2 种基金the Singapore Ministry of Education Academic Research Fund Tier 2(MOE2015-T2-1-016,MOE2018-T2-1-019,and MoE T1 R-284-000-196-114)the Singapore National Research Foundation(NRF-CRP10-2012-02)supported from SSLS via National University of Singapore Core Support(C-380-003-003-001).
文摘Strain gradient is a normal phenomenon around a heterostructural interface in ultrathin film,and it is important to determine its effect on magnetic interactions to understand interfacial coupling.In this work,ultrathin Pr_(0.67)Sr_(0.33)MnO_(3)(PSMO)films on different substrates are studied.For PSMO film under different in-plane strain conditions,the saturated magnetization and Curie temperature can be qualitatively explained by double-exchange interaction and the Jahn-Teller distortion.However,the difference in the saturated magnetization with zero field cooling and 5 T field cooling is proportional to the strain gradient.Strain-gradient-induced structural disorder is proposed to enhance phonon-electron antiferromagnetic interactions and the corresponding antiferromagnetic-to-ferromagnetic phase transition via a strong magnetic field during the field cooling process.A non-monotonous structural transition of the MnO_(6) octahedral rotation can enlarge the strain gradient in PSMO film on a SrTiO_(3) substrate.This work demonstrates the existence of the flexomagnetic effect in ultrathin manganite film,which should be applicable to other complex oxide systems.
基金supported by the National Natural Science Foundation of China[grant numbers 21703147 and U1401248],Chinathe Natural Science Foundations for the Young Scientist of Jiangsu Province[grant number BK20170338],Chinathe Open Fund of Jiangsu Key Laboratory of Materials and Technology for Energy Conversion[grant number MTEC-2017M01],China。
文摘Molybdenum oxide/sulfide materials are extensively evaluated as high-capacity anode candidates for lithium ion batteries.However,they suffer from rapid capacity decay and poor kinetics.Herein,we report on synergistic effect from structurally integrated coaxial CNTs@MoS_(2)/MoO_(2) composite material on lithium storage,in which MoS_(2)/MoO_(2) nanosheets are conformally decorated on carbon nanotubes(CNTs).In-situ synchrotron X-ray diffraction measurement is performed to elucidate synergistic effect among three MoS_(2),MoO_(2) and CNTs components for lithium storage.Reaction mechanism exploration reveals that the MoO_(2) component undergoes reversible Li^(+)intercalation via forming a stable Li_(0.98) MoO_(2) phase over a voltage range of 3.0 to 0.01 V vs.Li^(+)/Li,without experiencing the conversion reaction into metallic Mo,which contributes to long-term stability during charge/discharge cycles.Meanwhile,lithium storage of MoS_(2) is through lithium and sulfur reversible reaction after the initial conversion reaction of lithiated MoS_(2) forming Li_(2)S and Mo.The CNTs component enhances electronic conductivity and structural stability by minimizing volume change and reaction strains in the CNTs@MoS_(2)/MoO_(2) composite anode.A desired 68.2%capacity retention upon 2000 cycles at 10 A/g has been demonstrated for the CNTs@MoS_(2)/MoO_(2) anode,revealing prominent reaction kinetics and structural stability for fast and stable lithium storage,superior to various Mo-based anode materials previously reported.The findings from this study,with the unique insight into the role of structural integrity in combining MoS_(2)/MoO_(2) materials with the CNTs substrate,offers a strategy for designing composite anode materials for superior lithium storage performance.
基金the financial support of Spanish MINECO(PID2021-126509OB-C21,and Fondos FEDER)Catalan Government(2017-SGR-001500).
文摘Polarimetry encompasses a collection of optical techniques broadly used in a variety of fields.Nowadays,such techniques have provided their suitability in the biomedical field through the study of the polarimetric response of biological samples(retardance,dichroism and depolarization)by measuring certain polarimetric observables.One of these features,depolarization,is mainly produced by scattering on samples,which is a predominant efiect in turbid media as biological tissues.In turn,retardance and dichroic efiects are produced by tissue anisotropies and can lead to depolarization too.Since depolarization is a predominant efiect in tissue samples,we focus on studying difierent depolarization metrics for biomedical applications.We report the suitability of a set of depolarizing observables,the indices of polarimetric purity(IPPs),for biological tissue inspection.We review some results where we demonstrate that IPPs lead to better performance than the depolarization index,which is a well-established and commonly used depolarization observable in the literature.We also provide how IPPs are able to significantly enhance contrast between difierent tissue structures and even to reveal structures hidden by using standard intensity images.Finally,we also explore the classificatory potential of IPPs and other depolarizing observables for the discrimination of difierent tissues obtained from ex vivo chicken samples(muscle,tendon,myotendinous junction and bone),reaching accurate models for tissue classification.
文摘Carbonate electrolytes are one of the most desirable electrolytes for high-energy lithium-sulfur batteries(LSBs)because of their successful implementation in commercial Li-ion batteries.The low-polysulfide-solubility feature of some carbonate solvents also makes them very promising for overcoming the shuttle effects of LSBs.However,regular sulfur electrodes experience undesired electrochemical mechanisms in carbonate electrolytes due to side reactions.In this study,we report a catalytic redox mechanism of sulfur in propylene carbonate(PC)electrolyte based on a compari-son study.The catalytic mechanism is characterized by the interactions between polysulfides and dual N/O functional groups on the host carbon,which largely prevents side reactions between polysulfides and the carbonate electrolyte.Such a mechanism coupled with the low-polysulfide-solubility feature leads to stable cycling of LSBs in PC electrolyte.Favorable dual N/O functional groups are identified via a density functional theory study.This work provides an alternative route for enabling LSBs in carbonate electrolytes.
基金This work was supported by the Accelerator and Detector Research Program,part of the Scientific User Facility Division of the Basic Energy Science Office of the US Department of Energy(DOE),under the Field Work Proposal No.PS032This research was performed at the Optical Metrology Laboratory at the National Synchrotron Light Source II,a US DOE Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory(BNL)under Contract No.DE-SC0012704This work was performed under the BNL LDRD 17-016‘Diffraction limited and wavefront preserving reflective optics development’.
文摘Optics with high-precision height and slope are increasingly desired in numerous industrial fields.For instance,Kirkpatrick-Baez(KB)mirrors play an important role in synchrotron X-ray applications.A KB system is composed of two aspherical,grazing-incidence mirrors used to focus an X-ray beam.The fabrication of KB mirrors is challenging due to the aspherical departure of the mirror surfaces from base geometries and the high-quality requirements for slope and height residuals.In this paper,we present the process of manufacturing an elliptical cylinder KB mirror using our in-house-developed ion beam figuring(IBF)and metrology technologies.First,the key aspects of figuring and finishing processes with IBF are illustrated in detail.The effect of positioning error on the convergence of the residual slope error is highlighted and compensated.Finally,inspection and cross-validation using different metrology instruments are performed and used as the final validation of the mirror.Results confirm that relative to the requested off-axis ellipse,the mirror has achieved 0.15-μrad root mean square(RMS)and 0.36-nm RMS residual slope and height errors,respectively,while maintaining the initial 0.3-nm RMS microroughness.
基金The research leading to these results received funding from BiofuelNet Canada(funded by the Canadian Networks of Centers of Excellence)and the Leverhulme Trust.
文摘Biochar pores in the micrometer range(1-100μm)derive from cellular structures of the plant biomass subjected to pyrolysis or can be the result of mechanical processing,such as pelleting.In this study,synchrotron X-ray microtomography was used to investigate the internal pore structure of softwood pellet biochar produced by slow pyrolysis at 550 and 700°C.The microtomographic data sets consisted of 2025 images of 2560×2560 voxels with a voxel side length of 0.87μm.The three-dimensional reconstructions revealed that pelleting and pyrolysis significantly altered the pore structures of the wood feedstock,creating a network of connected pores between fragments that resembled the wood morphology.While higher pyrolysis temperature increased the specific surface area(as determined by BET nitrogen adsorption),it did not affect the total observed porosity.Multifractal analysis was applied to assess the characteristics of the frequency distribution of pores along each of the three dimensions of reconstructed images of five softwood pellet biochar samples.The resulting singular-ity and Rényi spectra(generalized dimensions)indicated that the distribution of porosity had monofractal scaling behavior,was homogeneous within the analyzed volumes and consistent between replicate samples.Moreover,the pore distributions were isotropic(direction-independent),which is in strong contrast with the anisotropic pore structure of wood.As pores at the scale analyzed in this study are relevant,for example,for the supply of plant accessible water and habitable space for microorganisms,our findings combined with the ability to reproduce biochar with such pore distribution offer substantial advantages in various biochar applications.
基金sponsored by Tsinghua-Toyota Joint Research Fund.This study used resources of 18-ID and 23-ID-2 of the National Synchrotron Light Source II,a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory under Contract No.DESC0012704.
文摘Integrated rocksalt-polyanion cathodes(DRXPS)are promising candidates for next-generation lithium-ion battery cathode materials that combine high energy density,stable cycling performance,and reduced reliance on Co and Ni.In this work,we investigated Li_(3)Mn_(1.6)P_(0.4)O_(5.4)F_(0.6),a new DRXPS cathode with fluoride incorporation.A pure spinel phase was formed and a discharge capacity retention of 84%was achieved after 200 cycles between 1.5 and 4.8 V versus Li/Li^(+).In comparison,the similarly synthesized Li_(3)Mn_(1.6)Nb_(0.4)O_(5.4)F_(0.6),in which all P^(5+)was substituted by Nb^(5+)while maintaining the same stoichiometry for all other elements,crystallized in a disordered rocksalt structure,and exhibited inferior capacity retention and rate capability than the P^(5+)counterpart.Our findings expand the compositional space of DRXPS to include F^(−),justify the viability of integrating polyanion groups in rocksalt-type cathodes,and highlight the superiority of P^(5+)as a cation charge compensator compared to the commonly used Nb^(5+).This work thereby advances the design of robust,high-performance cathode materials for sustainable batteries.
