N-doping has significant influence in manipulating the properties of TiO_(2),and this has stimulated the development of N-donor-functionalized titanium-oxo clusters(TOCs)as molecular models to study the structure-prop...N-doping has significant influence in manipulating the properties of TiO_(2),and this has stimulated the development of N-donor-functionalized titanium-oxo clusters(TOCs)as molecular models to study the structure-property relationship.However,the structural type and photoresponsive application are still limited for such TOCs,especially regarding the high-nuclearity TOCs that contain structure unit of TiO_(2)for photocatalysis.Herein,we showed the synthesis of a series of high-nuclearity TOCs 1-3 compounds usingπ-conjugated 1,10-phenanthroline(phen)as chromophore and N-donor functional ligand.Compound 1 features cocrystal structure composed of one[Ti_(26)]~(2+)and half[Ti_(22)]~(2+),which renders it as the first cocrystallized TOC containing two positively charged species and phen-functionalized TOC showing the highest nuclearity up to 37 Ti centers.By adjusting the synthetic conditions,the individual{Ti_(22)}and{Ti_(26)}clusters can also be isolated as Compounds 2 and 3,respectively.The core structure of{Ti_(22)}is mainly constructed from four lacunary{Ti_(4)}derived from pentagonal{Ti(Ti)_5}unit,while{Ti_(26)}is built from four complete{Ti(Ti)_5}unit.Notably,a{Ti_8O_(14)}structure unit of anatase TiO_(2)can be identified in{Ti_(26)}.Based on the unique structural features and proper photophysical and photochemical properties of Compounds 1-3,they are applied for photocatalytic sulfoxidation.Owing to the presence of anatase structure unit in{Ti_(26)}and the synergistic effect from{Ti_(22)}and{Ti_(26)},the catalytic performance presents in the order of Compound 1>Compound 3>Compound 2.This work provides excellent models to understand the structureproperty relationship from the perspective of cocrystallization and Ti-O binding model and will further promote the application of TOCs as functional catalysts for organic transformation.展开更多
The redox properties of ceria make it suitable as a catalyst or support in oxidation reactions.Ceria-supported transition metal nanoparticles or isolated single atoms provide a metal-support interface that reduces the...The redox properties of ceria make it suitable as a catalyst or support in oxidation reactions.Ceria-supported transition metal nanoparticles or isolated single atoms provide a metal-support interface that reduces the energy cost to remove interfacial oxygen atoms,providing active oxygen species that can participate in Mars van Krevelen oxidation processes.CO oxidation is a key probe reaction to test the reducibility of ceria-supported catalysts and is also practically important in the elimination of CO at relatively low temperatures in various applications.Preferential oxidation of CO(PROX)in excess H2 controls the CO concentration to ultra-low levels to prevent poisoning of hydrogen oxidation electrocatalysts.The reactivity of catalysts in CO oxidation and selectivity towards CO over H2 in PROX is dependent on the type and dispersion of metal species,the structural and chemical properties of Ce O2,and the synthetic preparation methods of the catalysts.In this review,we summarize recently published works on catalytic CO oxidation and PROX reactions on ceria-supported metal nanoparticles and single atoms.We summarize the reactivity on different supported metals,and on different Ce O2 surfaces with the same metal.We summarize the most likely reaction mechanisms as suggested by density functional theory calculations.The factors contributing to selectivity towards CO oxidation in PROX reactions on various supported metals are also discussed.展开更多
A one-pot strategy exploiting the structure directing effects of SeIV and TeIV heteroatoms has yielded the highest nuclearity noble metal containing polyoxometalates to date;including the palladium-rich selenotungstat...A one-pot strategy exploiting the structure directing effects of SeIV and TeIV heteroatoms has yielded the highest nuclearity noble metal containing polyoxometalates to date;including the palladium-rich selenotungstate isomers K_(28)[H_(12)Pd_(10)Se_(10)W_(52)O_(206)]·65H_(2)O(1)and K_(26)[H_(14)Pd_(10)Se_(10)W_(52)O_(2)06]·68H_(2)O(2),and the nanoscale tellurotungstate cluster Na_(40)[Pd_(6)Te_(19)W_(42)O_(190)]·76H_(2)O(3).These reaction systems exhibit remarkable structural flexibility and point to a new route towards the synthesis of complex heterometallic species,in which multiple lacunary polyoxometalate‘building blocks’have been assembled to trap a transient oxopalladate species suspected to play a role in the assembly of several common polyoxopalladates.Mass spectrometry has been applied to explore and compare the solution stability of compounds 1-3,demonstrating the markedly different properties of the SeIV and TeIV templated systems.Electrochemical analysis of 1 has been provided and is dominated by Pd redox processes,with reduction of the cluster resulting in electrodeposition of Pd metal and observation of the subsequent formation of PdO species,concurrent with previously reported oxopalladate containing species.展开更多
Given the fundamental role of C-C bond formation in synthetic chemistry,the development of effective acid-base catalysts is a significant and challenging endeavor.In this study,a high-nuclearity Ag-substituted tetrame...Given the fundamental role of C-C bond formation in synthetic chemistry,the development of effective acid-base catalysts is a significant and challenging endeavor.In this study,a high-nuclearity Ag-substituted tetrameric sandwich-type polyoxometalate was synthesized using simple materials via a one-pot strategy.The{Ag_(16)}cluster of the sandwich is protected and stabilized by four trivacant POM ligands,while four additional silver atom active sites remain exposed.Furthermore,compound 1 demonstrates considerable catalytic activity for C-C bond formation in the Knoevenagel condensation and cyanosilylation reactions,which can be attributed to its substantial acid-base active sites.展开更多
Constructing fullerene-like metal-organic cage integrating novel architectures and unique functions remains a formidable challenge.Herein,an unprecedented high-nuclearity fullerene-like heteropolyoxometalate cage,{Na_...Constructing fullerene-like metal-organic cage integrating novel architectures and unique functions remains a formidable challenge.Herein,an unprecedented high-nuclearity fullerene-like heteropolyoxometalate cage,{Na_(32)[(VVO_(2))_(30)(MoVIO_(4))_(12)(PhPO_(3))_(48)(CH_(3)COO)_(12)](CO_(3))_(2)}·5MeCN(Mo_(24)V_(30)P_(48),MeCN=acetonitrile),was successfully synthesized via a one-pot method.This anionic cluster can be described as a pseudo-cubic cage assembled from 12{Mo_(2)V_(2)P_(4)}quadrilaterals and 6{VO_(6)}octahedra.Sodium ions are employed as templates to fill the cage.The entire structure displays a distinct four-shell{Mo_(24)}@{V_(30)P_(48)}@{Na_(24)}@{Na_(8)}arrangement.Since all the{Mo_(2)}units and Na^(+)ions are located on the{V_(30)P_(48)}cage,this structure can also be simplified as a fullerene-like heterometallic cage composed of 12{Mo_(2)V_(2)P_(4)}hexagons,8{NaV_(3)P_(3)}hexagons,and 24{NaV_(2)P_(3)}pentagons.Additionally,Mo_(24)V_(30)P_(48) exhibits high solution stability,as confirmed by ESI-MS,PXRD and SEM,which makes it a highly efficient and stable catalyst for phenolic oxidation reactions.展开更多
The synthesis of superclusters is vital for understanding their self-assembly mechanisms,requiring precise control over composition,orientation,and connectivity.The tenets of reticular chemistry afford a systematic ap...The synthesis of superclusters is vital for understanding their self-assembly mechanisms,requiring precise control over composition,orientation,and connectivity.The tenets of reticular chemistry afford a systematic approach to the architectural design and regulation of molecular entities,thereby enabling the fulfillment of preconceived structural objectives.Herein,the strategic introduction of transition metal ions,CoⅡand NiⅡ,has enabled the controlled formation of two novel closely related anionic superclusters based on the{Sr⊂P_(6)M_(2)Mo_(16)O_(73)}clusters:Co_(12)Sr_(4)Mo_(80)P_(36)(1)and Na_(4)Ni_(23)Sr_(4)Mo_(88)P_(52)(2).The former manifests a tetrahedral structure,while the latter,derived from topological transformations of cluster 1,exhibits a unique square geometry.Structural elucidation revealed that the integration of MoV ions in a reduced state,in concert with distinct transition metal ions(CoⅡ and NiⅡ),plays a pivotal role in determining the geometric profiles of these superclusters.Furthermore,clusters 1 and 2 demonstrate efficacy as heterogeneous catalysts,significantly promoting the transformation of methyl phenyl sulfide(MPS)to methyl phenyl sulfoxide(MPSO).展开更多
It is highly desirable yet challenging to incorporate open micropores with mass transportation and open active metal sites into metal-organic frameworks(MOFs)for developing novel highly efficient catalysts.Herein,we r...It is highly desirable yet challenging to incorporate open micropores with mass transportation and open active metal sites into metal-organic frameworks(MOFs)for developing novel highly efficient catalysts.Herein,we report a catalyst of low-nuclearity copper-cluster-based micropore MOF,namely H-1e,incor-porated with unsaturated Cu(Ⅱ)centres as open active sites obtained via a highly efficient electrochemical synthesis within 20 minutes.The catalyst H-1e shows potential porosity with 1D open functionalized hexagonal channels for size-selective air oxidation as well as high stability.The electrochemically pre-pared H-1e exhibits excellent catalytic aerobic oxidation activity for the conversion of alcohols(mini-size)to aldehydes with over 99%selectivity and 99%yield under air conditions,showing excellent reusability and stability.The selective catalytic performances are found to be closely dependent on the suitable aperture size of the 1D channels in H-1e,which provided better beds for the oxidation transformations(confirmed by the computational DFT study).In this study,it offers a simple and potential strategy to con-struct microporous materials with open active metal sites to promote the catalytic efficiency of MOFs by electrochemical synthesis.展开更多
Strokes include both ischemic stroke,which is mediated by a blockade or reduction in the blood supply to the brain,and hemorrhagic stroke,which comprises intracerebral hemorrhage and subarachnoid hemorrhage and is cha...Strokes include both ischemic stroke,which is mediated by a blockade or reduction in the blood supply to the brain,and hemorrhagic stroke,which comprises intracerebral hemorrhage and subarachnoid hemorrhage and is characterized by bleeding within the brain.Stroke is a lifethreatening cerebrovascular condition characterized by intricate pathophysiological mechanisms,including oxidative stress,inflammation,mitochondrial dysfunction,and neuronal injury.Critical transcription factors,such as nuclear factor erythroid 2-related factor 2 and nuclear factor kappa B,play central roles in the progression of stroke.Nuclear factor erythroid 2-related factor 2 is sensitive to changes in the cellular redox status and is crucial in protecting cells against oxidative damage,inflammatory responses,and cytotoxic agents.It plays a significant role in post-stroke neuroprotection and repair by influencing mitochondrial function,endoplasmic reticulum stress,and lysosomal activity and regulating metabolic pathways and cytokine expression.Conversely,nuclear factor-kappa B is closely associated with mitochondrial dysfunction,the generation of reactive oxygen species,oxidative stress exacerbation,and inflammation.Nuclear factor-kappa B contributes to neuronal injury,apoptosis,and immune responses following stroke by modulating cell adhesion molecules and inflammatory mediators.The interplay between these pathways,potentially involving crosstalk among various organelles,significantly influences stroke pathophysiology.Advancements in single-cell sequencing and spatial transcriptomics have greatly improved our understanding of stroke pathogenesis and offer new opportunities for the development of targeted,individualized,cell typespecific treatments.In this review,we discuss the mechanisms underlying the involvement of nuclear factor erythroid 2-related factor 2 and nuclear factor-kappa B in both ischemic and hemorrhagic stroke,with an emphasis on their roles in oxidative stress,inflammation,and neuroprotection.展开更多
Analysis Method of ^(131)I Activity in Carbon Cartridge and Internal Dose Assessment for Nuclear Medicine Workers.Shuo Wang1,Fei Tuo1,Jian-feng Zhang1,Xiao-liang Li1,Bao-lu Yang1,Qiang Zhou1,Ze-shu Li1,Shu-ying Kong1,...Analysis Method of ^(131)I Activity in Carbon Cartridge and Internal Dose Assessment for Nuclear Medicine Workers.Shuo Wang1,Fei Tuo1,Jian-feng Zhang1,Xiao-liang Li1,Bao-lu Yang1,Qiang Zhou1,Ze-shu Li1,Shu-ying Kong1,and Wei-hao Qin1(1.National Institute for Radiological Protection,Chinese Center for Disease Control and Prevention,Beijing,100088,China.)展开更多
In this paper,we investigate local properties in the system of completely integral mapping spaces.We introduce notions of injectivity,local reflexivity,exactness,nuclearity,finite-represent ability and WEP in the syst...In this paper,we investigate local properties in the system of completely integral mapping spaces.We introduce notions of injectivity,local reflexivity,exactness,nuclearity,finite-represent ability and WEP in the system of completely integral mapping spaces.First we obtain that any finite-dimensional operator space is injective in the system of completely integral mapping spaces.Furthermore we prove that C is the unique nuclear operator space and the unique exact operator space in this system.We also show that C is the unique operator space which is finitely representable in{T_(n)}n∈Nin this system.As corollaries,Kirchberg’s conjecture and QWEP conjecture in the system of completely integral mapping spaces are false.展开更多
Hyperpolarization of nuclear spins is crucial for advancing nuclear magnetic resonance and quantum information technologies,as nuclear spins typically exhibit extremely low polarization at room temperature due to thei...Hyperpolarization of nuclear spins is crucial for advancing nuclear magnetic resonance and quantum information technologies,as nuclear spins typically exhibit extremely low polarization at room temperature due to their small gyromagnetic ratios.A promising approach to achieving high nuclear spin polarization is transferring the polarization of electrons to nuclear spins.The nitrogen-vacancy(NV)center in diamond has emerged as a highly effective medium for this purpose,and various hyperpolarization protocols have been developed.Among these,the pulsed polarization(PulsePol)method has been extensively studied due to its robustness against static energy shifts of the electron spin.In this work,we present a novel polarization protocol and uncover a family of magic sequences for hyperpolarizing nuclear spins,with PulsePol emerging as a special case of our general approach.Notably,we demonstrate that some of these magic sequences exhibit significantly greater robustness compared to the PulsePol protocol in the presence of finite half𝜋pulse duration of the protocol,Rabi and detuning errors.This enhanced robustness positions our protocol as a more suitable candidate for hyper-polarizing nuclear spins species with large gyromagnetic ratios and also ensures better compatibility with high-efficiency readout techniques at high magnetic fields.Additionally,the generality of our protocol allows for its direct application to other solid-state quantum systems beyond the NV center.展开更多
Nuclear receptor subfamily 2 group F member 1(NR2F1,also called COUP-TF1)is a transcription factor and part of the steroid/thyroid hormone receptor superfamily(Gay et al.,2002).NR2F1 is an orphan receptor that dimeriz...Nuclear receptor subfamily 2 group F member 1(NR2F1,also called COUP-TF1)is a transcription factor and part of the steroid/thyroid hormone receptor superfamily(Gay et al.,2002).NR2F1 is an orphan receptor that dimerizes to bind DNA and acts as a repressor as well as an activator of the target genes(Gay et al.,2002;Bertacchi et al.,2019;Bonzano et al.,2023).展开更多
A deep neural network(DNN)was developed to accurately predict the nuclear charge density distributions for nuclei with proton numbers Z≥8.By incorporating essential nuclear structure features,the model achieved a sig...A deep neural network(DNN)was developed to accurately predict the nuclear charge density distributions for nuclei with proton numbers Z≥8.By incorporating essential nuclear structure features,the model achieved a significant improvement in predictive accuracy over conventional methods.The charge density distributions were analyzed using a Fourier-Bessel(FB)series expansion,and the DNN was trained on a comprehensive dataset derived from relativistic continuum Hartree-Bogoliubov(RCHB)theory calculations.The model demonstrated exceptional performance,with root-mean-square deviations of 0.0123fm and 0.0198 fm for the charge radii on the training and validation sets,respectively,which remarkably surpassed the precision of the original RCHB calculations.In addition to advancing nuclear physics research,this high-precision model provides critical data for applications in atomic physics,nuclear astrophysics,and related fields.展开更多
To efficiently remove radioactive nuclides from nuclear industry wastewater and minimize the generation of radioactive secondary waste,this study proposes the concept of a magnetically controlled microchannel adsorber...To efficiently remove radioactive nuclides from nuclear industry wastewater and minimize the generation of radioactive secondary waste,this study proposes the concept of a magnetically controlled microchannel adsorber based on magnetic adsorbents.A novel protocol for achieving high adsorption performance in microchannel adsorbers with periodically distributed particles is developed using the particle-resolved computational fluid dynamics (CFD) method,which addresses the limitations of traditional porous media flow models.To align simulation results more closely with practical scenarios,a typical high-efficiency magnetic adsorbent,magnetic sodium alginate/cobalt-based Prussian blue (M-SA/PB-Co),was synthesized.The M-SA/PB-Co microspheres exhibit a uniform size distribution (300–600 μm),and their Cs^(+) adsorption follows the pseudo-second-order kinetic model with a Langmuir saturated adsorption capacity of 124.84 mg·g^(-1).The performance parameters of M-SA/PB-Co,obtained from characterization and adsorption experiments,were integrated into CFD simulations.CFD results indicate that as the flow velocity increases,the flow field gradually transitions with vortices expanding in scale and streamline bifurcation points shifting rearward.The Cs^(+) concentration decreases progressively along the flow direction,with a more pronounced reduction in the vortex regions downstream of particles.The characteristic velocity and characteristic concentration of specific regions surrounding the particles were extracted based on boundary layer distribution.The amount of concentration reduction of Cs^(+) through particle is positively correlated with the characteristic concentration and negatively correlated with the characteristic velocity.The number of microspheres required in the microchannel adsorber was optimized using the response surface method.Compared with industrial fixed-bed adsorbers,microchannel adsorbers exhibit 8–10 times higher processing capacity,demonstrating significant industrial application potential.展开更多
The genus Clematis(Ranunculaceae)comprises over 300 species with remarkable morphological and ecological diversity worldwide.Despite its horticultural,medicinal,and ecological importance,a well-resolved phylogeny and ...The genus Clematis(Ranunculaceae)comprises over 300 species with remarkable morphological and ecological diversity worldwide.Despite its horticultural,medicinal,and ecological importance,a well-resolved phylogeny and coherent infrageneric classification are still lacking.Here,we reconstruct a robust phylogeny for Clematis using a phylogenomic approach and revise its infrageneric taxonomy.We incorporated 198 samples representing 151 species,two subspecies,and 12 varieties,covering all subgenera and most sections worldwide,obtained from both fresh and herbarium material.Nuclear single nucleotide polymorphisms(SNPs)and complete plastid genomes were assembled for phylogenetic analyses.We also prepared a nuclear ribosomal ITS(nrITS)dataset comprising 171 species,two subspecies,and 12 varieties(217 samples)to include as many species as possible for phylogenetic inference.Phylogenies based on plastid genomes and nrITS exhibited limited resolution and modest support,highlighting challenges in resolving certain relationships.Nuclear SNP analyses yielded a robust phylogenetic tree with 22 well-supported clades corresponding to 22 sections,with most previously recognized subgenera and sections not recovered as monophyletic.Ancestral state reconstruction of 12 key morphological characters revealed multiple independent origins of character states.This study presents the first comprehensive sectional classification for Clematis based on robust phylogenomic evidence,redefines morphological characteristics for each section,and resolves long-standing taxonomic ambiguities.Our results establish a framework for future studies on the evolution,ecology,and horticultural potential of this globally significant genus.展开更多
The^(229)Th nucleus has attracted considerable attention due to the existence of its low-energy isomeric state;however,direct laser excitation in ionic systems poses significant challenges for current laser technologi...The^(229)Th nucleus has attracted considerable attention due to the existence of its low-energy isomeric state;however,direct laser excitation in ionic systems poses significant challenges for current laser technologies.In the^(229)Th^(3+)ion,the electronic bridge(EB)process enables the conversion of direct laser excitation into an effective two-photon process(I_(g),6d_(3/2)→I_(g),7_(p_(1/2))→I_(m),7_(s_(1/2))),thereby circumventing the requirement for laser radiation at 148 nm.In this work,we employ many-body perturbation theory(MBPT)to calculate the hyperfine structure constants and field shift factors for several low-lying excited states of the^(229)Th^(3+)ion.By combining these theoretical results with previously reported experimental data,we predict three transition frequencies associated with the EB process in the^(229)Th^(3+)ion and identify the most suitable transition pathway for EB-assisted nuclear excitation.展开更多
Reproductive diapause is an insect survival strategy in which reproduction temporarily halts in response to adverse environmental changes.This process is characterized by arrested ovarian development and lipid accumul...Reproductive diapause is an insect survival strategy in which reproduction temporarily halts in response to adverse environmental changes.This process is characterized by arrested ovarian development and lipid accumulation in females.A reduction in juvenile hormone(JH)biosynthesis is known to initiate reproductive diapause,but its regulatory mechanism remains unclear.Seven up(Svp),a transcription factor from the nuclear receptor family,plays a crucial role in various developmental processes in insects.In this study,using the cabbage beetle Colaphellus bowringi as a model,we observed higher expression of Svp in the heads of female adults under reproductive photoperiodic conditions(short-day[SD])compared to diapause conditions(long-day[LD]).RNA interference-mediated knockdown of Svp in SD females induced typical diapause phenotypes,including ovarian arrest and lipid accumulation.The application of methoprene(ME),a JH receptor agonist,reversed these diapause phenotypes and restored reproduction,indicating that Svp’s regulation of reproductive diapause is dependent on JH signaling.Additionally,Svp knockdown led to the downregulation of JH pathway genes and a reduction in JH titers.Further evidence suggested that Svp regulates the expression of JHAMT1,a critical gene in JH biosynthesis,which determines diapause entry in C.bowringi.These findings suggest that diapause-inducing photoperiods suppress Svp expression,blocking JH production and triggering diapause.This work reveals a critical transcription factor that regulates reproductive diapause initiation through modulating JH production,providing a potential target for controlling pests capable of entering reproductive diapause.展开更多
Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,...Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.展开更多
When the operating temperature of a solid oxide electrolysis cell(SOEC)is lower than the outlet temperature of a nuclear reactor,the reactor can be directly coupled with the SOEC as a high-temperature heat source.Howe...When the operating temperature of a solid oxide electrolysis cell(SOEC)is lower than the outlet temperature of a nuclear reactor,the reactor can be directly coupled with the SOEC as a high-temperature heat source.However,the key to the efficiency and return on investment of this hybrid energy system lies in the expected lifetime of the SOEC.This study assessed Ni-YSZ|YSZ|GDC|LSC fuel electrode support cells’long-term stability during electrolysis at 650℃with a current density of−0.5Acm^(−2)over 1818 h.The average voltage degradation rate of 2.63%kh^(−1)unfolded in two phases:an initial rapid decay(90 to 1120 h at 3.58%kh^(−1))and a stable decay(1120 to 1818 h at 2.14%kh^(−1)),emphasizing SOECs’probability coupling with nuclear reactors at 650℃.Post-1818-hour electrolysis revealed nickel particle formation associated with Ni(OH)_(x)diffusion and re-deposition,alongside a strontium-containing layer causing interface cracking.Despite minimal strontium segregation in the EDS,XPS data indicated surface segregation of Sr.This study provides crucial insights into prolonged SOEC operation,highlighting both its potential and challenges.展开更多
Nuclear heating plays an important aspect in design and deployment of both fission and fusion reactors and experimental devices in terms of cooling requirements. Two experimental campaigns in the framework of a collab...Nuclear heating plays an important aspect in design and deployment of both fission and fusion reactors and experimental devices in terms of cooling requirements. Two experimental campaigns in the framework of a collaboration project between the French Atomic and Alternative Energy Commission(CEA) and Jožef Stefan Institute(JSI), Slovenia, have been performed at the JSI TRIGA reactor for the experimental assessment of nuclear heating in fission and fusion-relevant materials by the differential calorimetry technique, based on the CALMOS and CARMEN differential calorimeters, previously developed at CEA. The results of the first campaign performed at reactor powers between 100 and 250 kW have already been reported, highlighting some measurement difficulties. Therefore, the second campaign was performed at a lower reactor power of 30 kW to overcome these issues. Moreover, a computational analysis of the experiments was performed using the JSIR2S code package to calculate the nuclear heating levels. Both experiments and their reproduction by simulations are described in detail. We present a comparison of the previously reported measured nuclear heating values of the first campaign with the computational results, with consistent underestimation by simulations by 8–35%. We report the experimental and computational results for the second experimental campaign performed at a reactor power of 30 kW. The simulated heating values were in agreement with the measurements within the measured heating uncertainty, with simulated heating 2.7–11.3% lower than the experimental values.展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.21901037,21901038 and 92161111)the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning+1 种基金the Fundamental Research Funds for the Central Universities(No.2232019G-07)the International Cooperation Fund of Science and Technology Commission of Shanghai Municipality(No.21130750100)。
文摘N-doping has significant influence in manipulating the properties of TiO_(2),and this has stimulated the development of N-donor-functionalized titanium-oxo clusters(TOCs)as molecular models to study the structure-property relationship.However,the structural type and photoresponsive application are still limited for such TOCs,especially regarding the high-nuclearity TOCs that contain structure unit of TiO_(2)for photocatalysis.Herein,we showed the synthesis of a series of high-nuclearity TOCs 1-3 compounds usingπ-conjugated 1,10-phenanthroline(phen)as chromophore and N-donor functional ligand.Compound 1 features cocrystal structure composed of one[Ti_(26)]~(2+)and half[Ti_(22)]~(2+),which renders it as the first cocrystallized TOC containing two positively charged species and phen-functionalized TOC showing the highest nuclearity up to 37 Ti centers.By adjusting the synthetic conditions,the individual{Ti_(22)}and{Ti_(26)}clusters can also be isolated as Compounds 2 and 3,respectively.The core structure of{Ti_(22)}is mainly constructed from four lacunary{Ti_(4)}derived from pentagonal{Ti(Ti)_5}unit,while{Ti_(26)}is built from four complete{Ti(Ti)_5}unit.Notably,a{Ti_8O_(14)}structure unit of anatase TiO_(2)can be identified in{Ti_(26)}.Based on the unique structural features and proper photophysical and photochemical properties of Compounds 1-3,they are applied for photocatalytic sulfoxidation.Owing to the presence of anatase structure unit in{Ti_(26)}and the synergistic effect from{Ti_(22)}and{Ti_(26)},the catalytic performance presents in the order of Compound 1>Compound 3>Compound 2.This work provides excellent models to understand the structureproperty relationship from the perspective of cocrystallization and Ti-O binding model and will further promote the application of TOCs as functional catalysts for organic transformation.
基金funding of this work by the National Science Foundation,Division of Chemical,Bioengineering,Environmental and Transport Systems(CBET)through Award#1800507 and 1510435。
文摘The redox properties of ceria make it suitable as a catalyst or support in oxidation reactions.Ceria-supported transition metal nanoparticles or isolated single atoms provide a metal-support interface that reduces the energy cost to remove interfacial oxygen atoms,providing active oxygen species that can participate in Mars van Krevelen oxidation processes.CO oxidation is a key probe reaction to test the reducibility of ceria-supported catalysts and is also practically important in the elimination of CO at relatively low temperatures in various applications.Preferential oxidation of CO(PROX)in excess H2 controls the CO concentration to ultra-low levels to prevent poisoning of hydrogen oxidation electrocatalysts.The reactivity of catalysts in CO oxidation and selectivity towards CO over H2 in PROX is dependent on the type and dispersion of metal species,the structural and chemical properties of Ce O2,and the synthetic preparation methods of the catalysts.In this review,we summarize recently published works on catalytic CO oxidation and PROX reactions on ceria-supported metal nanoparticles and single atoms.We summarize the reactivity on different supported metals,and on different Ce O2 surfaces with the same metal.We summarize the most likely reaction mechanisms as suggested by density functional theory calculations.The factors contributing to selectivity towards CO oxidation in PROX reactions on various supported metals are also discussed.
基金We thank the EPSRC funding(grants EP/H024107/1,EP/I033459/1,EP/J015156/1)EU FP7 Micreagents(318671)。
文摘A one-pot strategy exploiting the structure directing effects of SeIV and TeIV heteroatoms has yielded the highest nuclearity noble metal containing polyoxometalates to date;including the palladium-rich selenotungstate isomers K_(28)[H_(12)Pd_(10)Se_(10)W_(52)O_(206)]·65H_(2)O(1)and K_(26)[H_(14)Pd_(10)Se_(10)W_(52)O_(2)06]·68H_(2)O(2),and the nanoscale tellurotungstate cluster Na_(40)[Pd_(6)Te_(19)W_(42)O_(190)]·76H_(2)O(3).These reaction systems exhibit remarkable structural flexibility and point to a new route towards the synthesis of complex heterometallic species,in which multiple lacunary polyoxometalate‘building blocks’have been assembled to trap a transient oxopalladate species suspected to play a role in the assembly of several common polyoxopalladates.Mass spectrometry has been applied to explore and compare the solution stability of compounds 1-3,demonstrating the markedly different properties of the SeIV and TeIV templated systems.Electrochemical analysis of 1 has been provided and is dominated by Pd redox processes,with reduction of the cluster resulting in electrodeposition of Pd metal and observation of the subsequent formation of PdO species,concurrent with previously reported oxopalladate containing species.
基金financially supported by the National Natural Science Foundation of China(Grants 22171071,22171075,22071044,and 21771054).
文摘Given the fundamental role of C-C bond formation in synthetic chemistry,the development of effective acid-base catalysts is a significant and challenging endeavor.In this study,a high-nuclearity Ag-substituted tetrameric sandwich-type polyoxometalate was synthesized using simple materials via a one-pot strategy.The{Ag_(16)}cluster of the sandwich is protected and stabilized by four trivacant POM ligands,while four additional silver atom active sites remain exposed.Furthermore,compound 1 demonstrates considerable catalytic activity for C-C bond formation in the Knoevenagel condensation and cyanosilylation reactions,which can be attributed to its substantial acid-base active sites.
基金financially supported by the NSFC of China(no.22371032 and 22271023).
文摘Constructing fullerene-like metal-organic cage integrating novel architectures and unique functions remains a formidable challenge.Herein,an unprecedented high-nuclearity fullerene-like heteropolyoxometalate cage,{Na_(32)[(VVO_(2))_(30)(MoVIO_(4))_(12)(PhPO_(3))_(48)(CH_(3)COO)_(12)](CO_(3))_(2)}·5MeCN(Mo_(24)V_(30)P_(48),MeCN=acetonitrile),was successfully synthesized via a one-pot method.This anionic cluster can be described as a pseudo-cubic cage assembled from 12{Mo_(2)V_(2)P_(4)}quadrilaterals and 6{VO_(6)}octahedra.Sodium ions are employed as templates to fill the cage.The entire structure displays a distinct four-shell{Mo_(24)}@{V_(30)P_(48)}@{Na_(24)}@{Na_(8)}arrangement.Since all the{Mo_(2)}units and Na^(+)ions are located on the{V_(30)P_(48)}cage,this structure can also be simplified as a fullerene-like heterometallic cage composed of 12{Mo_(2)V_(2)P_(4)}hexagons,8{NaV_(3)P_(3)}hexagons,and 24{NaV_(2)P_(3)}pentagons.Additionally,Mo_(24)V_(30)P_(48) exhibits high solution stability,as confirmed by ESI-MS,PXRD and SEM,which makes it a highly efficient and stable catalyst for phenolic oxidation reactions.
基金financially supported by the National Natural Science Foundation of China(No.22271021,21971024,22201021,22101030).
文摘The synthesis of superclusters is vital for understanding their self-assembly mechanisms,requiring precise control over composition,orientation,and connectivity.The tenets of reticular chemistry afford a systematic approach to the architectural design and regulation of molecular entities,thereby enabling the fulfillment of preconceived structural objectives.Herein,the strategic introduction of transition metal ions,CoⅡand NiⅡ,has enabled the controlled formation of two novel closely related anionic superclusters based on the{Sr⊂P_(6)M_(2)Mo_(16)O_(73)}clusters:Co_(12)Sr_(4)Mo_(80)P_(36)(1)and Na_(4)Ni_(23)Sr_(4)Mo_(88)P_(52)(2).The former manifests a tetrahedral structure,while the latter,derived from topological transformations of cluster 1,exhibits a unique square geometry.Structural elucidation revealed that the integration of MoV ions in a reduced state,in concert with distinct transition metal ions(CoⅡ and NiⅡ),plays a pivotal role in determining the geometric profiles of these superclusters.Furthermore,clusters 1 and 2 demonstrate efficacy as heterogeneous catalysts,significantly promoting the transformation of methyl phenyl sulfide(MPS)to methyl phenyl sulfoxide(MPSO).
基金supported by the International Scientific and Technological Cooperation Foundation of Science and Technology Department of Jilin province(No.20200801041GH)Science and Technology Department of Changchun(21ZGM02),P.R.China.
文摘It is highly desirable yet challenging to incorporate open micropores with mass transportation and open active metal sites into metal-organic frameworks(MOFs)for developing novel highly efficient catalysts.Herein,we report a catalyst of low-nuclearity copper-cluster-based micropore MOF,namely H-1e,incor-porated with unsaturated Cu(Ⅱ)centres as open active sites obtained via a highly efficient electrochemical synthesis within 20 minutes.The catalyst H-1e shows potential porosity with 1D open functionalized hexagonal channels for size-selective air oxidation as well as high stability.The electrochemically pre-pared H-1e exhibits excellent catalytic aerobic oxidation activity for the conversion of alcohols(mini-size)to aldehydes with over 99%selectivity and 99%yield under air conditions,showing excellent reusability and stability.The selective catalytic performances are found to be closely dependent on the suitable aperture size of the 1D channels in H-1e,which provided better beds for the oxidation transformations(confirmed by the computational DFT study).In this study,it offers a simple and potential strategy to con-struct microporous materials with open active metal sites to promote the catalytic efficiency of MOFs by electrochemical synthesis.
基金supported by grants from the Zhejiang Provincial TCM Science and Technology Plan Project,No.2023ZL156(to YH)Ningbo Top Medical and Health Research Program,No.2022020304(to XG)+1 种基金the Natural Science Foundation of Ningbo,No.2023J019(to YH)Key Laboratory of Precision Medicine for Atherosclerotic Diseases of Zhejiang Province,No.2022E10026(to YH)。
文摘Strokes include both ischemic stroke,which is mediated by a blockade or reduction in the blood supply to the brain,and hemorrhagic stroke,which comprises intracerebral hemorrhage and subarachnoid hemorrhage and is characterized by bleeding within the brain.Stroke is a lifethreatening cerebrovascular condition characterized by intricate pathophysiological mechanisms,including oxidative stress,inflammation,mitochondrial dysfunction,and neuronal injury.Critical transcription factors,such as nuclear factor erythroid 2-related factor 2 and nuclear factor kappa B,play central roles in the progression of stroke.Nuclear factor erythroid 2-related factor 2 is sensitive to changes in the cellular redox status and is crucial in protecting cells against oxidative damage,inflammatory responses,and cytotoxic agents.It plays a significant role in post-stroke neuroprotection and repair by influencing mitochondrial function,endoplasmic reticulum stress,and lysosomal activity and regulating metabolic pathways and cytokine expression.Conversely,nuclear factor-kappa B is closely associated with mitochondrial dysfunction,the generation of reactive oxygen species,oxidative stress exacerbation,and inflammation.Nuclear factor-kappa B contributes to neuronal injury,apoptosis,and immune responses following stroke by modulating cell adhesion molecules and inflammatory mediators.The interplay between these pathways,potentially involving crosstalk among various organelles,significantly influences stroke pathophysiology.Advancements in single-cell sequencing and spatial transcriptomics have greatly improved our understanding of stroke pathogenesis and offer new opportunities for the development of targeted,individualized,cell typespecific treatments.In this review,we discuss the mechanisms underlying the involvement of nuclear factor erythroid 2-related factor 2 and nuclear factor-kappa B in both ischemic and hemorrhagic stroke,with an emphasis on their roles in oxidative stress,inflammation,and neuroprotection.
文摘Analysis Method of ^(131)I Activity in Carbon Cartridge and Internal Dose Assessment for Nuclear Medicine Workers.Shuo Wang1,Fei Tuo1,Jian-feng Zhang1,Xiao-liang Li1,Bao-lu Yang1,Qiang Zhou1,Ze-shu Li1,Shu-ying Kong1,and Wei-hao Qin1(1.National Institute for Radiological Protection,Chinese Center for Disease Control and Prevention,Beijing,100088,China.)
基金Supported by the National Natural Science Foundation of China(Grant No.11871423)Zhejiang Provincial Natural Science Foundation of China(Grant No.LQ21A010015)。
文摘In this paper,we investigate local properties in the system of completely integral mapping spaces.We introduce notions of injectivity,local reflexivity,exactness,nuclearity,finite-represent ability and WEP in the system of completely integral mapping spaces.First we obtain that any finite-dimensional operator space is injective in the system of completely integral mapping spaces.Furthermore we prove that C is the unique nuclear operator space and the unique exact operator space in this system.We also show that C is the unique operator space which is finitely representable in{T_(n)}n∈Nin this system.As corollaries,Kirchberg’s conjecture and QWEP conjecture in the system of completely integral mapping spaces are false.
基金supported by the National Natural Science Foundation of China (Grant Nos.12475012,62461160263 for P.W.,and 62276171 for H.L.)Quantum Science and Technology-National Science and Technology Major Project of China (Project No.2023ZD0300600 for P.W.)+3 种基金Guangdong Provincial Quantum Science Strategic Initiative (Grant Nos.GDZX240-3009 and GDZX2303005 for P.W.)Guangdong Basic and Applied Basic Research Foundation (Grant No.2024-A1515011938 for H.L.)Shenzhen Fundamental ResearchGeneral Project (Grant No.JCYJ20240813141503005 for H.L.)the Talents Introduction Foundation of Beijing Normal University (Grant No.310432106 for P.W.)。
文摘Hyperpolarization of nuclear spins is crucial for advancing nuclear magnetic resonance and quantum information technologies,as nuclear spins typically exhibit extremely low polarization at room temperature due to their small gyromagnetic ratios.A promising approach to achieving high nuclear spin polarization is transferring the polarization of electrons to nuclear spins.The nitrogen-vacancy(NV)center in diamond has emerged as a highly effective medium for this purpose,and various hyperpolarization protocols have been developed.Among these,the pulsed polarization(PulsePol)method has been extensively studied due to its robustness against static energy shifts of the electron spin.In this work,we present a novel polarization protocol and uncover a family of magic sequences for hyperpolarizing nuclear spins,with PulsePol emerging as a special case of our general approach.Notably,we demonstrate that some of these magic sequences exhibit significantly greater robustness compared to the PulsePol protocol in the presence of finite half𝜋pulse duration of the protocol,Rabi and detuning errors.This enhanced robustness positions our protocol as a more suitable candidate for hyper-polarizing nuclear spins species with large gyromagnetic ratios and also ensures better compatibility with high-efficiency readout techniques at high magnetic fields.Additionally,the generality of our protocol allows for its direct application to other solid-state quantum systems beyond the NV center.
文摘Nuclear receptor subfamily 2 group F member 1(NR2F1,also called COUP-TF1)is a transcription factor and part of the steroid/thyroid hormone receptor superfamily(Gay et al.,2002).NR2F1 is an orphan receptor that dimerizes to bind DNA and acts as a repressor as well as an activator of the target genes(Gay et al.,2002;Bertacchi et al.,2019;Bonzano et al.,2023).
基金the National Natural Science Foundation of China(No.12475119)the Key Laboratory of Nuclear Data Foundation(JCKY2025201C154)the JSPS Grant-in-Aid for Scientific Research(S)(No.20H05648)。
文摘A deep neural network(DNN)was developed to accurately predict the nuclear charge density distributions for nuclei with proton numbers Z≥8.By incorporating essential nuclear structure features,the model achieved a significant improvement in predictive accuracy over conventional methods.The charge density distributions were analyzed using a Fourier-Bessel(FB)series expansion,and the DNN was trained on a comprehensive dataset derived from relativistic continuum Hartree-Bogoliubov(RCHB)theory calculations.The model demonstrated exceptional performance,with root-mean-square deviations of 0.0123fm and 0.0198 fm for the charge radii on the training and validation sets,respectively,which remarkably surpassed the precision of the original RCHB calculations.In addition to advancing nuclear physics research,this high-precision model provides critical data for applications in atomic physics,nuclear astrophysics,and related fields.
基金Dalian distinguished young scholars program(2022RJ17)the Dalian excellent young talents program(2023RY037)provided funding for this study.
文摘To efficiently remove radioactive nuclides from nuclear industry wastewater and minimize the generation of radioactive secondary waste,this study proposes the concept of a magnetically controlled microchannel adsorber based on magnetic adsorbents.A novel protocol for achieving high adsorption performance in microchannel adsorbers with periodically distributed particles is developed using the particle-resolved computational fluid dynamics (CFD) method,which addresses the limitations of traditional porous media flow models.To align simulation results more closely with practical scenarios,a typical high-efficiency magnetic adsorbent,magnetic sodium alginate/cobalt-based Prussian blue (M-SA/PB-Co),was synthesized.The M-SA/PB-Co microspheres exhibit a uniform size distribution (300–600 μm),and their Cs^(+) adsorption follows the pseudo-second-order kinetic model with a Langmuir saturated adsorption capacity of 124.84 mg·g^(-1).The performance parameters of M-SA/PB-Co,obtained from characterization and adsorption experiments,were integrated into CFD simulations.CFD results indicate that as the flow velocity increases,the flow field gradually transitions with vortices expanding in scale and streamline bifurcation points shifting rearward.The Cs^(+) concentration decreases progressively along the flow direction,with a more pronounced reduction in the vortex regions downstream of particles.The characteristic velocity and characteristic concentration of specific regions surrounding the particles were extracted based on boundary layer distribution.The amount of concentration reduction of Cs^(+) through particle is positively correlated with the characteristic concentration and negatively correlated with the characteristic velocity.The number of microspheres required in the microchannel adsorber was optimized using the response surface method.Compared with industrial fixed-bed adsorbers,microchannel adsorbers exhibit 8–10 times higher processing capacity,demonstrating significant industrial application potential.
基金funded by the National Natural Science Foundation of China(grant no.31670207).
文摘The genus Clematis(Ranunculaceae)comprises over 300 species with remarkable morphological and ecological diversity worldwide.Despite its horticultural,medicinal,and ecological importance,a well-resolved phylogeny and coherent infrageneric classification are still lacking.Here,we reconstruct a robust phylogeny for Clematis using a phylogenomic approach and revise its infrageneric taxonomy.We incorporated 198 samples representing 151 species,two subspecies,and 12 varieties,covering all subgenera and most sections worldwide,obtained from both fresh and herbarium material.Nuclear single nucleotide polymorphisms(SNPs)and complete plastid genomes were assembled for phylogenetic analyses.We also prepared a nuclear ribosomal ITS(nrITS)dataset comprising 171 species,two subspecies,and 12 varieties(217 samples)to include as many species as possible for phylogenetic inference.Phylogenies based on plastid genomes and nrITS exhibited limited resolution and modest support,highlighting challenges in resolving certain relationships.Nuclear SNP analyses yielded a robust phylogenetic tree with 22 well-supported clades corresponding to 22 sections,with most previously recognized subgenera and sections not recovered as monophyletic.Ancestral state reconstruction of 12 key morphological characters revealed multiple independent origins of character states.This study presents the first comprehensive sectional classification for Clematis based on robust phylogenomic evidence,redefines morphological characteristics for each section,and resolves long-standing taxonomic ambiguities.Our results establish a framework for future studies on the evolution,ecology,and horticultural potential of this globally significant genus.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB0920403)the National Key Research and Development Program of China(Grant No.2022YFB3904002).
文摘The^(229)Th nucleus has attracted considerable attention due to the existence of its low-energy isomeric state;however,direct laser excitation in ionic systems poses significant challenges for current laser technologies.In the^(229)Th^(3+)ion,the electronic bridge(EB)process enables the conversion of direct laser excitation into an effective two-photon process(I_(g),6d_(3/2)→I_(g),7_(p_(1/2))→I_(m),7_(s_(1/2))),thereby circumventing the requirement for laser radiation at 148 nm.In this work,we employ many-body perturbation theory(MBPT)to calculate the hyperfine structure constants and field shift factors for several low-lying excited states of the^(229)Th^(3+)ion.By combining these theoretical results with previously reported experimental data,we predict three transition frequencies associated with the EB process in the^(229)Th^(3+)ion and identify the most suitable transition pathway for EB-assisted nuclear excitation.
基金funded by the National Natural Science Foundation of China,China(grant no.32472543).
文摘Reproductive diapause is an insect survival strategy in which reproduction temporarily halts in response to adverse environmental changes.This process is characterized by arrested ovarian development and lipid accumulation in females.A reduction in juvenile hormone(JH)biosynthesis is known to initiate reproductive diapause,but its regulatory mechanism remains unclear.Seven up(Svp),a transcription factor from the nuclear receptor family,plays a crucial role in various developmental processes in insects.In this study,using the cabbage beetle Colaphellus bowringi as a model,we observed higher expression of Svp in the heads of female adults under reproductive photoperiodic conditions(short-day[SD])compared to diapause conditions(long-day[LD]).RNA interference-mediated knockdown of Svp in SD females induced typical diapause phenotypes,including ovarian arrest and lipid accumulation.The application of methoprene(ME),a JH receptor agonist,reversed these diapause phenotypes and restored reproduction,indicating that Svp’s regulation of reproductive diapause is dependent on JH signaling.Additionally,Svp knockdown led to the downregulation of JH pathway genes and a reduction in JH titers.Further evidence suggested that Svp regulates the expression of JHAMT1,a critical gene in JH biosynthesis,which determines diapause entry in C.bowringi.These findings suggest that diapause-inducing photoperiods suppress Svp expression,blocking JH production and triggering diapause.This work reveals a critical transcription factor that regulates reproductive diapause initiation through modulating JH production,providing a potential target for controlling pests capable of entering reproductive diapause.
基金supported by the National Key Research and Development Program of China(2024YFA1612900)the National Natural Science Foundation of China(Grant No.52103365 and No.12375270)the Guangdong Innovative and Entrepreneurial Research Team Program,China(Grant No.2021ZT09L227).
文摘Fine-grained nuclear graphite is a key material in high-temperature gas-cooled reactors(HTGRs).During air ingress accidents,core graphite components undergo severe oxidation,threatening structural integrity.Therefore,understanding the oxidation behavior of nuclear graphite is essential for reactor safety.The influence of oxidation involves multiple factors,including temperature,sample size,oxidant,impurities,filler type and size,etc.The size of the filler particles plays a crucial role in this study.Five ultrafine-and superfine-grained nuclear graphite samples(5.9-34.4μm)are manufactured using identical raw materials and manufacturing processes.Isothermal oxidation tests conducted at 650℃-750℃ are used to study the oxidation behavior.Additionally,comprehensive characterization is performed to analyze the crystal structure,surface morphology,and nanoscale to microscale pore structure of the samples.Results indicate that oxidation behavior cannot be predicted solely based on filler grain size.Reactive site concentration,characterized by active surface area,dominates the chemical reaction kinetics,whereas pore tortuosity,quantified by the structural parameterΨ,plays a key role in regulating oxidant diffusion.These findings clarify the dual role of microstructure in oxidation mechanisms and establish a theoretical and experimental basis for the design of high-performance nuclear graphite capable of long-term service in high-temperature gas-cooled reactors.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0400000)the Youth Innovation Promotion Association of the Chinese Academy of Sciences(No.2021253)+1 种基金the Major Science and Technology Projects of China National Offshore Oil Corporation Limited during the 14th Five Year Plan(No.KJGG-2022-12-CCUS-030500)the Photon Science Center for Carbon Neutrality of Chinese Academy of Science.
文摘When the operating temperature of a solid oxide electrolysis cell(SOEC)is lower than the outlet temperature of a nuclear reactor,the reactor can be directly coupled with the SOEC as a high-temperature heat source.However,the key to the efficiency and return on investment of this hybrid energy system lies in the expected lifetime of the SOEC.This study assessed Ni-YSZ|YSZ|GDC|LSC fuel electrode support cells’long-term stability during electrolysis at 650℃with a current density of−0.5Acm^(−2)over 1818 h.The average voltage degradation rate of 2.63%kh^(−1)unfolded in two phases:an initial rapid decay(90 to 1120 h at 3.58%kh^(−1))and a stable decay(1120 to 1818 h at 2.14%kh^(−1)),emphasizing SOECs’probability coupling with nuclear reactors at 650℃.Post-1818-hour electrolysis revealed nickel particle formation associated with Ni(OH)_(x)diffusion and re-deposition,alongside a strontium-containing layer causing interface cracking.Despite minimal strontium segregation in the EDS,XPS data indicated surface segregation of Sr.This study provides crucial insights into prolonged SOEC operation,highlighting both its potential and challenges.
基金supported by the Slovenian Research Agency(research project NC-0001-Analysis of nuclear heating in a reactor,research core funding Reactor physics No.P2-0073,infrastructure program I0-0005)。
文摘Nuclear heating plays an important aspect in design and deployment of both fission and fusion reactors and experimental devices in terms of cooling requirements. Two experimental campaigns in the framework of a collaboration project between the French Atomic and Alternative Energy Commission(CEA) and Jožef Stefan Institute(JSI), Slovenia, have been performed at the JSI TRIGA reactor for the experimental assessment of nuclear heating in fission and fusion-relevant materials by the differential calorimetry technique, based on the CALMOS and CARMEN differential calorimeters, previously developed at CEA. The results of the first campaign performed at reactor powers between 100 and 250 kW have already been reported, highlighting some measurement difficulties. Therefore, the second campaign was performed at a lower reactor power of 30 kW to overcome these issues. Moreover, a computational analysis of the experiments was performed using the JSIR2S code package to calculate the nuclear heating levels. Both experiments and their reproduction by simulations are described in detail. We present a comparison of the previously reported measured nuclear heating values of the first campaign with the computational results, with consistent underestimation by simulations by 8–35%. We report the experimental and computational results for the second experimental campaign performed at a reactor power of 30 kW. The simulated heating values were in agreement with the measurements within the measured heating uncertainty, with simulated heating 2.7–11.3% lower than the experimental values.
