摘要：Actinide-based catalysts have been regarded as promising candidates for N_(2) fixation owing to their unique 5f orbital with flexible oxidation ***,we report for the first time the dispersion of uranium(U)single atoms on TiO_(2) nanosheets via oxygen vacancy confinement for N_(2) *** single-atom U catalyst exhibited a high NH_(3) yield of 40.57μg h^(-1) mg^(-1),with a reasonably high Faraday efficiency of 25.77%,ranking first among the reported nitrogen-free ***-labeling operando synchrotron infrared spectroscopy verifies that the key*N_(2)H_(y) intermediate species was derived from the N_(2) gas of the *** using operando X-ray absorption spectroscopy,we found enhanced metal-support interaction between U single atoms and TiO_(2) lattice with more U-O_(latt) coordination under working *** simulations suggest that the evolved 1O_(ads)-U-4O_(latt) moieties act as a critical electronfeedback center,lowering the thermodynamic energy barrier for the N_(2) dissociation and the first hydrogenation *** work provides the possibility of tailoring the interaction between metal active sites and supports for designing high-performance actinide-based single-atom catalysts.

摘要：A set of acoustic optimization design methods is established by combining the flow field deterioration theory and the acoustic analogy theory,and applied to the acoustic optimization design of high-speed train *** results show that the streamline bodies of the head/tail car are the most important sound sources,respectively,accounting for 23.7%and 33.7%of the total sound *** with the streamline body of tail head,the streamline body of head car is more biased towards high frequency for the sound source *** A-weighted radiated noise of the train body is characterized by broadband sound(mainly in the range of 1-4 kHz)and peak features(especially at 2 kHz).The snow-plough with the maximum expansion length can mitigate the strong peak effect of the sound at 2 kHz,reduce the total sound energy,and show the best acoustic radiation performance in the four *** numerical computation model was checked by the wind tunnel test results.

摘要：The pursuit of high-mileage models results in the recurrence of lithium metal batteries(LMBs)to researchers’***,the lithium(Li)metal anode for LMBs undergoes the uncontrollable formation of Li dendrites and infinite volume change during cycling,impeding its practical *** overcome these challenges,we developed a metal-organic framework(MOF)-derived pathway to construct lithiophilic three-dimensional(3d)skeleton using different substrates(e.g.,carbon cloth(CC)and Cu mesh)for dendrite-free lithium metal *** a typical example,the MOF-derived ZnO/nitrogen-doped carbon(NC)nanosheet-modified 3d CC was well-constructed as a lithiophilic hierarchical host(CC@ZnO/NC@Li)for molten Li *** from the lithiophilic N-functional groups and LiZn alloy,the synthesized CC@ZnO/NC@Li composite anode promoted the uniform distribution of Li,resulting in a dendrite-free ***,the 3d conductive carbon skeleton enhanced the reaction kinetics and buffered the volume change of the *** CC@ZnO/NC@Li composite anode presented a prolonged lifespan of over 1000 cycles at 5 mA cm^(−2) with a low overpotential of 19 *** with a LiFePO_(4) cathode,the CC@ZnO/NC@Li composite anode also exhibited superior electrochemical properties in the full-cell *** versatile strategy may open up the channel of designing multi-functional lithiophilic 3d hosts for the Li metal anode.

摘要：The significance of bioink suitability for the extrusion bioprinting of tissue-like constructs cannot be ***,derived from the hydrolysis of collagen,not only can mimic the extracellular matrix to immensely support cell function,but also is suitable for extrusion under certain ***,gelatin has been recognized as a promising bioink for extrusion ***,the development of a gelatin-based bioink with satisfactory printability and bioactivity to fabricate complex tissue-like constructs with the desired physicochemical properties and biofunctions for a specific biomedical application is still in its ***,in this review,we aim to comprehensively summarize the state-of-the-art methods of gelatin-based bioink application for extrusion ***firstly outline the properties and requirements of gelatin-based bioinks for extrusion bioprinting,highlighting the strategies to overcome their main limitations in terms of printability,structural stability and cell ***,the challenges and prospects are further discussed regarding the development of ideal gelatin-based bioinks for extrusion bioprinting to create complex tissue-like constructs with preferable physicochemical properties and biofunctions.

摘要：Camelid single-domain antibody fragments(nanobodies)are an emerging force in therapeutic biopharmaceuticals and clinical diagnostic reagents in recent *** all nanobodies available to date have been obtained by animal immunization,a bottleneck restricting the large-scale application of *** this study,we developed three kinds of gene designatedregion pan-editing(GdP)technologies to introduce multiple mutations in complementarity-determining regions(Cdrs)of nanobodies in *** the integration of G-quadruplex fragments in Cdrs,which induces the spontaneous multiple mutations in Cdrs;however,these mutant sequences are highly similar,resulting in a lack of sequences diversity in the *** also used Cdr-targeting traditional grNA-guided base-editors,which effectively diversify the *** most importantly,we developed the self-assembling grNAs,which are generated by reprogrammed tracrrNA hijacking of endogenous mrNAs as *** base-editors guided by self-assembling grNAs,we can realize the iteratively diversify the *** we believe the last GdP technology is highly promising in immunization-free nanobody library construction,and the full development of this novel nanobody discovery platform can realize the synthetic evolution of nanobodies in vitro.

摘要：Zero thermal expansion(ZTE)alloys have unique aspects in the application of the engineering of precise dimensional ***,the harsh conditions to realize ZTE,i.e.,appropriate coupling among spin,lattice,and charge upon heating,have limited the ZTE alloys by very few numbers of *** this work,we report a route to achieving twodimensional(2d)ZTE behavior by regulating crystallographic texture and magneto-volume effects(MVEs)in volumetric positive thermal expansion *** is illustrated in a series of Mn_(x)Fe_(5-x)Si_(3)compounds by those earth-abundant *** a result,a 2d ZTE performance with a coefficient of thermal expansion α_(1)=0.45×10^(-7)K^(-1) over a broad temperature window of 10–310 K was observed in *** experimental results by synchrotron X-ray diffraction,neutron diffraction,microscopy,and magnetization measurements reveal that such a ZTE behavior is strongly coupled with fiber crystallographic texture and magnetic moment at the crystallographic 6g site that dominates MVEs in the a-b *** competition between ferromagnetic Fe_(4d)–Fe_(6g)(J_(FM))and antiferromagnetic Mn_(4d)–Mn_(6g)(J_(AFM))interactions makes the Mn_(1.5)Fe_(3.5)Si_(3) and Mn_(2)Fe_(3)Si_(3)compounds show mixed magnetism and negative thermal expansion(NTE).The integral approach presented here can be used to extend the scope of ZTE/NTE species in other magnetic or ferroelectric materials.

摘要：Calculating the flow coefficient of a spool-valve is complicated due to the coupling–throttling effect in the throttling grooves of a proportional–directional *** this paper,a methodology for expressing the flow coefficient of coupled throttling grooves is proposed to resolve that *** this purpose,an approach of a 3 d numerical simulation and an experimental bench were introduced based on the prototype of a commercial proportional *** results show consistency between the numerical simulation and the bench *** on that,the concept of‘saturation limit’is introduced to describe the value gap between the current and saturated flows,so that the flow-coefficient saturation limit of the prototype in the process can be ***,an approximate flow coefficient suitable for coupled throttling grooves within finite variable space,which is based on three typical throttling structures(i.e.O-shape,U-shape,and C-shape)of the coupled throttling grooves,is obtained based on an orthogonal *** model results are consistent with the numerical and experimental results,with maximum errors of less than 5.29%and 5.34%,*** suggests that the proposed method is effective in approximating the flow coefficient.

摘要：High-temperature proton exchange membrane fuel cells(HT-PEMFCs)bring new opportunities for portable power generation due to their outstanding advantages such as high tolerance to fuel/air impurities and simplified heat/water ***,carbon-supported nanostructured Pt-based catalysts running at temperatures over 150℃are challenged by the severe aggregation and carbon corrosion,thus leading to poor ***,we demonstrate that dendritic Pt-Ni nanoparticles supported on fluorinated carbon black(white carbon black)could significantly enhance the performance and durability of HT-PEMFCs as the cathode catalysts running at 160℃due to the strong interaction of the F and Ni atoms to form a Ni_(x)F_(y) interface on Pt-Ni *** the formation of a stable Ni_(x)F_(y) interface,this integrated HT-PEMFC reached peak power densities of 906 mW cm^(−2) and demonstrated excellent durability at 160℃ under anhydrous H_(2)/O_(2) *** mitigation strategy was applied to Pt-alloy/C electrocatalysts and resulted in the elimination of Pt dissolution in practical fuel cells.

摘要：The past decade has witnessed a surge of interest in exploring emergent particles in condensed matter *** particles,emerged as excitations around exotic band degeneracy points,continue to be reported in real materials and artificially engineered systems,but so far,we do not have a complete picture on all possible types of particles that can be ***,via systematic symmetry analysis and modeling,we accomplish a complete list of all possible particles in time-reversal-invariant *** includes both spinful particles such as electron quasiparticles in solids,and spinless particles such as phonons or even excitations in electric-circuit and mechanical *** establish detailed correspondence between the particle,the symmetry condition,the effective model,and the topological *** obtained encyclopedia concludes the search for novel emergent particles and provides concrete guidance to achieve them in physical systems.

摘要：水凝胶作为承载组织的替代产品引起了广泛关注.然而,与能够通过有限的变形来承受复杂载荷的承载组织不同,传统的水凝胶由于其柔软的特性,无法在低应变状态下表现出刚性响应.基于承载组织的软硬组分之间的协同作用,我们设计了采用软基质(正泊松比)和硬框架(负泊松比)的复合水凝胶,其刚度分别比基质和框架高18.9和4.2倍.相反,结合软基质(正泊松比)和框架(正泊松比)的设计对刚度增强有限.通过有限元分析,揭示了软基质与框架之间正、负泊松比斥力作用的内在机理.本研究为今后设计基于软硬组分协同效应的复合水凝胶提供了思路.