Microscopic Magnetism of Nickel-Based Infinite-Layer Superconducting Parent Compounds RNiO_(2)(R=La,Nd):A μSR Study

By using muon spin relaxation(μSR)measurements,we perform a comparative study of the microscopic magnetism in the parent compounds of infinite-layer nickelate superconductors RNiO_(2)(R=La,Nd).In either compound,the zero-fieldμSR spectra down to the lowest measured temperature reveal no long-range magnetic order.In LaNiO_(2),short-range spin correlations appear below T=150 K,and spins fully freeze below T∼10 K.NdNiO_(2)exhibits a more complex spin dynamics driven by the Nd 4f and Ni3d electron spin fluctuations.Further,it shows features suggesting the proximity to a spin-glass state occurring below T=5 K.In both compounds,the spin behavior with temperature is further confirmed by longitudinal-field μSR measurements.These results provide new insight into the magnetism of the parent compounds of the superconducting nickelates,crucial to understanding the microscopic origin of their superconductivity.

Improving nitrogen management for zero-tillage rice in China

Zero-tillage has become increasingly attractive in rice production in China.This study was conducted to determine the feasibility of two possible improved N management practices with fewer N applications in zero-tillage rice:(1)two split applications of urea at75 kg N ha^(-1)at mid-tillering and 45 kg N ha^(-1)at panicle initiation(U_(120–2)),and(2)a single application of cross-linked polyacrylamide-coated urea(a slow-release fertilizer)at midtillering at a rate of 150 kg N ha^(-1)(PCU_(150–1)).Three field experiments were conducted to compare grain yield and N-use efficiency among several N treatments:a zero-N control(CK),U_(120–2),PCU_(150–1),a single application of urea at mid-tillering at a rate of 150 kg N ha^(-1)(U_(150–1)),and a commonly recommended N management practice for conventional tillage rice(three split applications of urea with 75 kg N ha^(-1)as basal,30 kg N ha^(-1)at mid-tillering,and 45 kg N ha^(-1)at panicle initiation)(U_(150–3)).Treatments with N application(U_(120–2),PCU_(150–1),U_(150–1),and U_(150–3))produced 1.08–3.16 t ha^(-1)higher grain yields than CK.Grain yields under both U_(120–2)and PCU_(150–1)were comparable to that in U_(150–3).Recovery efficiency of N(RE_N),agronomic N-use efficiency(AE_N)and partial factor productivity of applied N(PFP_N)were increased under U_(120–2)and were similar under PCU_(150–1)to those under U_(150–3).U_(150–1)showed lower grain yield,RE_N,AE_N,and PFP_Nthan U_(150–3).These results suggest that U_(150–3)can be replaced with U_(120–2)to achieve both an increase in N-use efficiency and a reduction in number of N applications and or by PCU_(150–1)to achieve a maximum reduction in number of N applications in zero-tillage rice production in China.

NH_(3)‑Induced In Situ Etching Strategy Derived 3D‑Interconnected Porous MXene/Carbon Dots Films for High Performance Flexible Supercapacitors

2D MXene(Ti_(3)CNT_(x))has been considered as the most promising electrode material for flexible supercapacitors owing to its metallic conductivity,ultra-high capacitance,and excellent flexibility.However,it suffers from a severe restacking problem during the electrode fabrication process,limiting the ion transport kinetics and the accessibility of ions in the electrodes,especially in the direction normal to the electrode surface.Herein,we report a NH_(3)-induced in situ etching strategy to fabricate 3D-interconnected porous MXene/carbon dots(p-MC)films for high-performance flexible supercapacitor.The pre-intercalated carbon dots(CDs)first prevent the restacking of MXene to expose more inner electrochemical active sites.The partially decomposed CDs generate NH_(3)for in situ etching of MXene nanosheets toward 3D-interconnected p-MC films.Benefiting from the structural merits and the 3D-interconnected ionic transmission channels,p-MC film electrodes achieve excellent gravimetric capacitance(688.9 F g^(-1)at 2 A g^(-1))and superior rate capability.Moreover,the optimized p-MC electrode is assembled into an asymmetric solid-state flexible supercapacitor with high energy density and superior cycling stability,demonstrating the great promise of p-MC electrode for practical applications.

Revealing the dominant factor of domain boundary resistance on bulk conductivity in lanthanum lithium titanates

Perovskite-type lithium lanthanum titanates(LLTO)display a high bulk ionic conductivity and are considered a promising electrolyte for building up to advanced solid-state Li-ion batteries.The LLTO crystals contain a high concentration of intrinsically formed 90ο-rotated domain boundaries(DBs)serving as barriers to bulk Li-ion conduction.However,the mechanism of how the DB concentration and DB resistance can compete with each other to determine the bulk conductivity of LLTO is still unknown.Here we report a comprehensive study of LLTO compounds,aimed to unravel the mechanism and hence explore new path(s)for further improving the conductivity of this material.Our results show that both the sintering temperature and chemical composition can affect significantly the domain structures in LLTO.It is found that a decrease in the DB concentration is always accompanied by increased DB resistance due to the increased lattice mismatch at DBs,and vice versa.By unifying the electrochemical impedance spectroscopy and transmission electron microscopy analysis,it is clearly shown that the high DB resistance,instead of DB concentration,acts as the dominant factor governing the bulk conductivity of LLTO.The results thus renew the conventional understanding of the bulk Li-ion conduction in LLTO and shed light on developing novel LLTO electrolyte materials with improved ionic conductivity.

材料、能源、机械工程中高效的电流变技术——从机理到应用

电流变(ER)技术是一种基于电流变效应的先进技术。电流变技术中最常见的材料是电流变液(ERF)。电流变液是一种软物质智能材料,其黏度可以通过施加电场来可逆地调节。电流变液的衍生物、一种新型的电响应软物质材料——电流变弹性体(ERE),由于其不沉降、易封装的优点也得到了越来越多的关注。电流变材料由于其可逆可调、快速响应、低能耗等特性在机械工程中有着广泛的应用。除了基础的电流变材料的合成和应用以外,电流变技术还应用在了能源材料制备、石油运输、储能等诸多领域。电流变技术在能源领域的应用为其在其他领域的潜在应用提供了一个很好的范例。本文结合最新的研究成果,从机理到应用,系统地综述了电流变技术在材料、能源和机械工程等领域的研究现状和未来发展前景。

Enhancing reversibility of LiNi_(0.5)Mn_(1.5)O_(4)by regulating surface oxygen deficiency

Oxygen deficiency has crucial effects on the crystal structure and electrochemical performance of spinel oxide lithium electrode materials such as LiNi_(0.5)Mn_(1.5)O_(4)(LNMO)cathode.In particular,the oxygen stoichiometry on the crystal surface differs from that on the crystal interior in LNMO.The detection of local oxygen loss in LNMO and its correlation with the crystal structure and the cycling stability of LNMO remain challenging.In this study,the effect of oxygen deficiency in LNMO controlled by sintering temperature on the surface crystal structure and electrochemical performance of LNMO is comprehensively investigated.The high concentration of oxygen vacancies segregates at the surface regions of LNMO forming a thin rock‐salt and/or deficient spinel surface layer.The atomic‐level surface structure reconstruction was demonstrated by annular dark‐field and annular brightfield techniques.For the synthesis of LNMO,the higher sintering temperature results in higher crystallinity but the higher oxygen deficiency in LNMO.The high crystallinity of LNMO would increase the thermal stability of LNMO cathodes while the high content of oxygen deficiency would decrease the surface structural stability of LNMO.Therefore,the LNMO sintered at a medium temperature of 850°C achieved the best capacity retention.The results suggest a competitive function mechanism between oxygen stoichiometry and the crystallinity of LNMO on the cycling performance of LNMO.

LnCu_(3)(OH)_(6)Cl_(3) (Ln=Gd, Tb, Dy): Heavy lanthanides on spin-1/2 kagome magnets

The spin-1/2 kagome antiferromagnets are key prototype materials for studying frustrated magnetism.Three isostructural kagome antiferromagnets LnCu_(3)(OH)_(6)Cl_(3)(Ln=Gd,Tb,Dy)have been successfully synthesized by the hydrothermal method.LnCu_(3)(OH)_(6)Cl_(3) adopts space group P3m1 and features the layered Cu-kagome lattice with lanthanide Ln3+cations sitting at the center of the hexagons.Although heavy lanthanides(Ln=Gd,Tb,Dy)in LnCu_(3)(OH)_(6)Cl_(3) provide a large effective magnetic moment and ferromagnetic-like spin correlations compared to light-lanthanides(Nd,Sm,Eu)analogues,Cu-kagome holds an antiferromagnetically ordered state at around 17 K like YCu_(3)(OH)_(6)Cl_(3).

Cooling Rate Dependence of Structural Order and Energy Landscape in Zr_(55)Cu_(35)Al_(10) Glass

Classical molecular dynamics simulation has been widely used to study the rapid cooling process of preparing amorphous alloys.However,the simulated cooling rate is several orders of magnitude higher than the experimental cooling rate.In this paper,Zr_(55)Cu_(35)Al_(10)alloy was taken as an example.It is found that adding isothermal annealing at a temperature slightly lower than Tand prolonging isothermal annealing time could effectively reduce the cooling rate.The glassy sample prepared in this way demonstrates significant energetic stability and well-developed short-range and medium-range order.

Structural Properties and Energy Analysis of Zr_(x)Cu_(90-x)Al_(10)Ternary Metallic Glasses

Classical molecular dynamics(MD)were conducted to study the structure and energy distribution of Zr_(x)Cu_(90-x)Al_(10)(x=20,30,40,50,60,70)ternary alloys.When the Zr composition is 30%,the glass transition temperature reaches the maximum value and the Zr_(30)Cu_(60)Al_(10)owns high glass forming ability(GFA).Analysis of the short⁃range structure shows that there are more low⁃energy Zr⁃centered polyhedron with high coordination number(CN)and Cu and Al⁃centered coordination polyhedron with CN=12 in Zr_(30)Cu_(60_Al_(10)alloy.As the medium⁃range structure is concerned,Zr_(30)Cu_(60_Al_(10)alloy has the largest number of coordination polyhedron connection sharing three atoms and connection in this way presenting the lowest energy.These low⁃energy and stable short and medium⁃range structures contribute to the high GFA of Zr_(30)Cu_(60_Al_(10).

AISI M2钢中M2C共晶碳化物的形貌和性能

在AISIM2钢铸态组织中，主要类型的共晶碳化物是M2C，其形态对碳化物在最终产品中的尺寸和分布有关键性的影响。在本研究中，用光学显微镜（OM）扫描电镜（SEM）能谱分析（EDS）透射电镜（TEM）x射线衍射（XRD）和差热分析（DTA），对在不同冷却条件下形成的M：C碳化物的形态和性能进行了研究，随冷却速度增加，M2C的形态从层状转变为棒状，凝固过程中2种类型的碳化物显示出不同的生长特性，与层状碳化物相比，棒状M2C碳化物的稳定性较差，即使热形变后，在较高温度时分解很快，加速碳化物的分离和球化。这说明在铸锭中M2C碳化物的形成促进在最终产品中碳化物的同质分布和细化，有益于改善高速钢的机械性能。

A novel marine-derived anti-acute kidney injury agent targeting peroxiredoxin 1 and its nanodelivery strategy based on ADME optimization

Insufficient therapeutic strategies for acute kidney injury(AKI)necessitate precision therapy targeting its pathogenesis.This study reveals the new mechanism of the marine-derived anti-AKI agent,piericidin glycoside S14,targeting peroxiredoxin 1(PRDX1).By binding to Cys83 of PRDX1 and augmenting its peroxidase activity,S14 alleviates kidney injury efficiently in Prdx1-overexpression(Prdx1-OE)mice.Besides,S14 also increases PRDX1 nuclear translocation and directly activates the Nrf2/HO-1/NQO1 pathway to inhibit ROS production.Due to the limited druggability of S14 with low bioavailability(2.6%)and poor renal distribution,a pH-sensitive kidney-targeting dodecanaminechitosan nanoparticle system is constructed to load S14 for precise treatment of AKI.L-Serine conjugation to chitosan imparts specificity to kidney injury molecule-1(Kim-1)-overexpressed cells.The developed S14-nanodrug exhibits higher therapeutic efficiency by improving the in vivo behavior of S14 significantly.By encapsulation with micelles,the AUC_(0-t),half-life time,and renal distribution of S14 increase 2.5-,1.8-,and 3.1-fold,respectively.The main factors contributing to the improved druggability of S14 nanodrugs include the lower metabolic elimination rate and UDPglycosyltransferase(UGT)-mediated biotransformation.In summary,this study identifies a new therapeutic target for the marine-derived anti-AKI agent while enhancing its ADME properties and druggability through nanotechnology,thereby driving advancements in marine drug development for AKI.

Atomistic origin of high grain boundary resistance in solid electrolyte lanthanum lithium titanate

Lanthanum lithium titanate is one of the promising electrolytes for solid-state lithium-ion batteries due to its high bulk ionic conductivity up to∼10^(−3) S/cm.However,the practical application of this material has been bottlenecked by high grain boundary(GB)resistance,while the underlying mechanism is still under debate.Here we report a comprehensive study with direct evidence to reveal the origin of high GB resistance in La_(2/3)–xLi_(3x)TiO_(3)(LLTO).Atomic-scale observations via advanced scanning transmission electron microscopy show that the GBs are uniformly subject to subsurface segregation of La atoms to compensate for the excess surface charges.The La segregation leads to an abrupt decrease of charge carrier concentration neighboring GBs and hence is supposed to have deleterious effect on GB conductivity.The findings suggest a novel mechanism of space-charge-induced cation segregation,which shed lights on the intrinsic origin of low GB ionic conductivity in LLTO.

数字普惠金融、资本错配与区域绿色创新效率

绿色创新能够带来经济高质量发展和生态保护的双重回报,以数字普惠金融为代表的数字经济能够通过合理配置资本对区域绿色创新效率提升发挥重要作用。本文以中国29个省级行政区域为样本,基于空间杜宾面板模型研究数字普惠金融对区域绿色创新效率的影响,以及资本错配在两者之间的中介效应与溢出效应,并进一步探讨了数字普惠金融各维度的差异及其经济后果。研究结论表明:数字普惠金融能够促进区域绿色创新效率的提升,且资本错配在两者之间发挥中介效应以及中介的溢出效应。进一步基于数字普惠金融的三个维度研究发现资本错配在覆盖广度、使用深度与区域绿色创新效率之间发挥中介的溢出效应,但在数字化程度与区域绿色创新效率之间难以发挥中介效应。

Binding Se into nitrogen-doped porous carbon nanosheets for high-performance potassium storage

Selenium cathode has been demonstrated as a promising candidate of cathode material for low-cost and high-energy density potassium ion batteries(PIBs).Nevertheless,their applica tions are prevented by poor electrochemical perfor-mance due to the shuttle effect of high-order polyselenides,the sluggish diffu-sion of bigger K+,and the huge volumetric expansion during cycling.In this work,we design a multifunctional Se host(N-HCNS)by grafting ZIF-8 derived microporous carbon onto the surface of N-doped porous carbon nanosheets.The obtained N-HCNS carbon matrix integrates conductivity,captivity,and immobility abilities,which inhibits the polyselenides shuttle,improves the Se utilization,and buffers the volume change during cycling.The 3D hollow car-bon skeleton enhances the infiltration of electrolytes.As an cathode for PIBs,the Se@N-HCNS electrode delivers an unprecedented life-span(260 mAh g1 at 1.0 Ag-1 after 2000 cycles)and exhibits a remarkable rate capacity(339 mAh g at 5.0 Ag-l).Density functional theory(DFT)calculation reveals the effective adsorption of K2Se with pyridine and pyrrole nitrogen dop-ing in carbon matrix.The unique synergetic design of electrode not only gives insight into the reaction mechanism but also highly emphasi zes the potential capabilities of N doped carbon in K-Se batteries.

Chemistry,Biosynthesis,and Biological Activity of Halogenated Compounds Produced by Marine Microorganisms

Natural products derived from marine microorganisms have been received great attention as a potential source of new compound entities for drug discovery.The unique marine environment brings us a large group of halogen-containing natural products with abundant biological functionality and good drugability.Meanwhile,biosynthetically halogenated reactions are known as a significant strategy used to increase the pharmacological activities and pharmacokinetic properties of compounds.Given that a tremendous increase in the number of new halogenated compounds from marine microorganisms in the last five years,it is necessary to summarize these compounds with their diverse structures and promising bioactivities.In this review,we have summarized the chemistry,biosynthesis(related halogenases),and biological activity of a total of 316 naturally halogenated compounds from marine microorganisms covering the period of 2015 to May 2021.Those reviewed chlorinated and brominated compounds with the ratio of 9:1 were predominantly originated from 36 genera of fungi(62%)and 9 bacterial strains(38%)with cytotoxic,antibacterial,and enzyme inhibitory activities,structural types of which are polyketides(38%),alkaloids(27%),phenols(11%),and others.This review would provide a plenty variety of promising lead halogenated compounds for drug discovery and inspire the development of new pharmaceutical agents.

Determination of the predictive factors for diagnostic positivity of nucleic acid amplification tests for diagnosing pulmonary tuberculosis

Background:Tuberculosis(TB)remains a major threat to human health,and TB diagnostic methods remain unsatisfactory.Nucleic acid amplification tests(NAATs)show higher sensitivity compared with culture for the diagnosis of pulmonary TB(PTB).However,NAATs are expensive and cannot be easily implemented outside major medical centers.To improve the sensitivity of NAATs for PTB diagnosis,we investigated the predictive factors that might optimize NAAT utilization.Methods:A total of 1263 patients with suspected PTB were enrolled for evaluation.The sensitivity,specificity,and accuracy of methods including smear-microbiology,culture of Mtb and NAAT for Mycobacterium tuberculosis(Mtb)detection in sputum and bronchoalveolar lavage fluid samples were compared.Odds ratios and 95%confidence intervals were used to assess variables that might be associated with positive NAAT results for sputum and bronchoalveolar lavage fluid from patients with suspected PTB.Results:NAAT showed higher sensitivity for Mtb detection(61.1%)when compared with smear(9.0%)and Mtb culture(47.8%).We found that an elevated erythrocyte sedimentation rate,the presence of cavities,and positive interferon-𝛾release assay(IGRA)results were indicative of positive Mtb detection by NAAT.Moreover,individuals who had all three of these characteristics showed an 86%diagnostic positivity for PTB from Mtb detection by NAAT.Conclusions:Our study suggests that an elevated erythrocyte sedimentation rate,a positive IGRA result,and the presence of pulmonary cavities are helpful factors for predicting positive Mtb detection by NAAT.Patients with the three positive clinical markers should undergo NAAT for Mtb detection because they are the most likely individuals to be bacteriologically confirmed as having TB.