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Light-triggered fluorochromic cholesteric liquid crystal elastomer with hydrogen-bonded fluorescent switch: dualmodal-switchable circularly polarized luminescence

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Science China Chemistry 2024年第8期67卷 2719-2727页

作者： Siyang Lin Tianqi Ren Xianyu Meng Wenxin Kang Jinbao Guo Key Laboratory of Carbon Fibers and Functional Polymers Ministry of EducationCollege of Materials Science and EngineeringBeijing University of Chemical TechnologyBeijing 100029China

Solid materials with dynamically tunable circularly polarized luminescence(CPL) feature higher security levels and devicefriendly characteristics, showing great superiority in the field of information technology and anti-counterfeiting. To address the limited photoisomerization of fluorescent photoswitch in CPL-active solid materials, here a cholesteric liquid crystal elastomer(CLCE) containing a hydrogen-bonded(H-bonded) polymerizable fluorescent switch AHBA-PSD is prepared. Owing to the good flexibility and low glass-transition temperature of CLCE, AHBA-PSD shows a fast and fully reversible photocyclization/cycloreversion with fluorochromic behavior in CLCE. Further, by controlling the spectral overlapping area between the emission and reflection bands, the CLCE exhibits a strong CPL with a g_(lum) value of up to 0.76 accompanied by a reversible phototunable CPL signal. Meanwhile, the H-bond helps to stabilize the mechanical property, and the force-induced switching-off of CPL signal could be achieved due to the destroyed helical structures by external force. Finally, an automatically-recognized identification card with abundant chiroptical information is demonstrated.

关键词： cholesteric liquid crystal elastomer circularly polarized luminescence fluorescent photoswitch diarylethene photoismerization

Deep-reinforcement-learning-based water diversion strategy

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Environmental Science and Ecotechnology 2024年第1期17卷 68-79页

作者： Qingsong Jiang Jincheng Li Yanxin Sun Jilin Huang Rui Zou Wenjing Ma Huaicheng Guo Zhiyun Wang Yong Liu State Environmental Protection Key Laboratory of All Materials Flux in River Ecosystems College of Environmental Sciences and EngineeringPeking UniversityBeijing100871PR China Rays Computational Intelligence Lab Beijing Inteliway Environmental Ltd.Beijing100085PR China Yunnan Key Laboratory of Pollution Process and Management of Plateau Lake-Watershed Yunnan Research Academy of Eco-environmental SciencesKunming650034PR Chin

Water diversion is a common strategy to enhance water quality in eutrophic lakes by increasing available water resources and accelerating nutrient *** effectiveness depends on changes in the source water and lake ***,the challenge of optimizing water diversion remains because it is difficult to simultaneously improve lake water quality and minimize the amount of diverted ***,we propose a new approach called dynamic water diversion optimization(DWDO),which combines a comprehensive water quality model with a deep reinforcement learning *** applied DWDO to a region of Lake Dianchi,the largest eutrophic freshwater lake in China and validated *** results demonstrate that DWDO significantly reduced total nitrogen and total phosphorus concentrations in the lake by 7%and 6%,respectively,compared to previous ***,annual water diversion decreased by an impressive 75%.Through interpretable machine learning,we identified the impact of meteorological indicators and the water quality of both the source water and the lake on optimal water *** found that a single input variable could either increase or decrease water diversion,depending on its specific value,while multiple factors collectively influenced real-time adjustment of water ***,using well-designed hyperparameters,DWDO proved robust under different uncertainties in model *** training time of the model is theoretically shorter than traditional simulation-optimization algorithms,highlighting its potential to support more effective decisionmaking in water quality management.

关键词： Dynamic water diversion optimization Deep reinforcement learning Process-based model Explainable decision-making Parameter uncertainty

Temporal Unfolding of Racial Ingroup Bias in Neural Responses to Perceived Dynamic Pain in Others

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Neuroscience Bulletin 2024年第2期40卷 157-170页

作者： Chenyu Pang Yuqing Zhou Shihui Han School of Psychological and Cognitive Sciences PKU-IDG/McGovern Institute for Brain ResearchBeijing Key Laboratory of Behavior and Mental HealthPeking UniversityBeijing 100081China CAS Key Laboratory of Behavioral Science Institute of PsychologyChinese Academy of SciencesBeijing 100101China Department of Psychology University of Chinese Academy of SciencesBeijing 100049China

In this study,we investigated how empathic neural responses unfold over time in different empathy networks when viewing same-race and other-race individuals in dynamic painful *** recorded magnetoencephalography signals from Chinese adults when viewing video clips showing a dynamic painful(or non-painful)stimulation to Asian and White models’faces to trigger painful(or neutral)*** found that perceived dynamic pain in Asian models modulated neural activities in the visual cortex at 100 ms–200 ms,in the orbitofrontal and subgenual anterior cingulate cortices at 150 ms–200 ms,in the anterior cingulate cortex around 250 ms–350 ms,and in the temporoparietal junction and middle temporal gyrus around 600 ms after video *** dynamic pain in White models modulated activities in the visual,anterior cingulate,and primary sensory cortices after 500 *** findings unraveled earlier dynamic activities in multiple neural circuits in response to same-race(vs other-race)individuals in dynamic painful situations.

关键词： Empathy Race Magnetoencephalography Dynamic pain Cingulate cortex

Inner fission barriers of uranium isotopes in the deformed relativistic Hartree-Bogoliubov theory in continuum

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Chinese Physics C 2024年第10期48卷 214-221页

作者： Wei Zhang Jin-Ke Huang Ting-Ting Sun Jing Peng Shuang-Quan Zhang School of Physics Zhengzhou UniversityZhengzhou 450001China Department of Physics Beijing Normal UniversityBeijing 100875China State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China

The inner fission barriers of the even-even uranium isotopes from the proton to the neutron drip line are examined using the deformed relativistic Hartree-Bogoliubov theory in continuum.A periodic-like evolution for the ground state shapes is shown with respect to the neutron number,i.e.,spherical shapes at shell closures 126,184,258,and prolate dominated shapes between *** to the shape evolution,the inner fission barriers also exhibit a periodic-like behavior:peaks at the shell closures and valleys in the *** triaxial effect on the inner fission barrier is evaluated using triaxial relativistic mean field calculations combined with a simple BCS method for *** the triaxial correction is included,the inner barrier heights show good consistency with available empirical ***,the evolution from the proton to the neutron drip line aligns with results from the multi-dimensionally constrained relativistic mean field theory.A flat valley in the fission barrier height is predicted around the neutron-rich nucleus U which may play a role of fission recycling in astrophysical r-process nucleosynthesis.

关键词： inner fission barrier potential energy curve triaxiality deformed relativistic Hartree-Bogoliubov theory in continuum

Natural products inspired[3+2]cycloaddition enables efficient construction of hydroxylated tetrahydrofuran acetals and concise syntheses of lignans

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Science China Chemistry 2024年第7期67卷 2306-2313页

作者： Dong-Yue Cai Weiming Shi Zhao-Hui Jin Zhi-Xiang Yu Jin-Xin Zhao Jian-Min Yue State Key Laboratory of Drug Research Shanghai Institute of Materia MedicaChinese Academy of SciencesShanghai 201203China university of Chinese Academy of Sciences Beijing 100049China Beijing National Laboratory for Molecular Sciences(BNLMS) Key Laboratory of Bioorganic Chemistry and Molecular Engineering of Ministry of EducationCollege of ChemistryPeking UniversityBeijing 100871China

Mimicking biosynthetic pathways of hongkonoids led to the development of a new Cu(Ⅰ)-catalyzed[3+2]cycloaddition ofα-hydroxyketone andβ-keto enol ethers,affording tetrahydrofuran acetals in a highly diastereoselective manner and 100%atom *** studies on the mechanism disclosed a concerted but asynchronous Michael addition/aldol *** the same importance,this methodology provides a practical biomimetic approach for one-step construction of the dibenzylbutyrolactol lignan backbone starting from two phenyl propane derivatives,opening up a powerful new approach for lignan synthesis,which is showcased by succinct total syntheses of two biologically important aryltetralin-type lignans,β-apopicropodophyllin and *** the mild and operationally simple conditions,the developed chemistry might have a promising prospect in potential industrial applications.

关键词： [3+2]cycloaddition transition-metal catalysis tetrahydrofuran lignans natural products

Principal components of nuclear mass models

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 65-71页

作者： Xin-Hui Wu Pengwei Zhao Department of Physics Fuzhou UniversityFuzhou 350108China State Key Laboratory of Nuclear Physics and Technology School of PhysicsPeking UniversityBeijing 100871China

Principal component analysis(PCA)is employed to extract the principal components(PCs)present in nuclear mass models for the first *** effects from different nuclear mass models are reintegrated and reorganized in the extracted *** PCs are recombined to build new mass models,which achieve better accuracy than the original theoretical mass *** comparison indicates that using the PCA approach,the effects contained in different mass models can be collaborated to improve nuclear mass predictions.

关键词： nuclear mass principal component analysis nuclear models statistical methods

Temperature-dependent self-trapped exciton emission in Cu(I) doped zinc-based metal halides from well-resolved excited state structures

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Nano Research 2024年第8期17卷 7768-7775页

作者： Yunlong Bai Shuai Zhang Nengneng Luo Bingsuo Zou Ruosheng Zeng State Key Laboratory of Featured Metal Materials and Life-cycle Safety for Composite Structures School of Physical Science and TechnologyGuangxi UniversityNanning 530004China

Zero-dimensional metal halides are of unique structures and tunable photoluminescence properties,showing great potential applications such as light-emitting diodes(LEDs)and ***,we successfully synthesized Cu^(+)doped(MA)_(2)ZnCl_(4)metal halides by a slow evaporation solvent *** introduction of Cu^(+)results in sky-blue self-trapped exciton emission in(MA)_(2)ZnCl_(4) at 486 nm at room temperature,and a photoluminescence quantum yield is as high as 54.9%.Interestingly,at low temperatures,Cu^(+)-doped(MA)_(2)ZnCl_(4) exhibits two emission peaks located at 482 and 605 nm,*** temperaturedependent dual emission indicates two excited state structures that exist on the triplet excited-state potential energy *** addition,the temperature sensor we fitted has good performance(Sr=1.65%·K^(−1)),which is the first attempt in Cu^(+) doped Znbased metal *** work enriches the family of sky-blue metal halides and provides a promising strategy for building skyblue LEDs.

关键词： sky-blue emission self-trapped exciton metal halides excited state structures temperature sensor

Scalar dark energy models and scalar–tensor gravity:theoretical explanations for the accelerated expansion of the present Universe

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Communications in Theoretical Physics 2024年第10期76卷 160-189页

作者： Peixiang Ji Lijing Shao Department of Astronomy School of Physics Peking University Kavli Institute for Astronomy and Astrophysics Peking University National Astronomical Observatories Chinese Academy of Sciences

The reason for the present accelerated expansion of the Universe stands as one of the most profound questions in the realm of science, with deep connections to both cosmology and fundamental physics. From a cosmological point of view, physical models aimed at elucidating the observed expansion can be categorized into two major classes: dark energy and modified gravity. We review various major approaches that employ a single scalar field to account for the accelerating phase of our present Universe. Dynamic system analysis was employed in several important models to find cosmological solutions that exhibit an accelerating phase as an *** scalar field models of dark energy, we consistently focused on addressing challenges related to the fine-tuning and coincidence problems in cosmology, as well as exploring potential solutions to them. For scalar–tensor theories and their generalizations, we emphasize the importance of constraints on theoretical parameters to ensure overall consistency with experimental tests. Models or theories that could potentially explain the Hubble tension are also emphasized throughout this review.

关键词： cosmology dark energy dynamic system modified gravity quintessence

Pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy for activating water and urea oxidation

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Green Energy & Environment 2024年第4期9卷 684-694页

作者： Guangfu Qian Wei Chen Jinli Chen Li Yong Gan Tianqi Yu Miaojing Pan Xiaoyan Zhuo Shibin Yin Guangxi Key Laboratory of Electrochemical Energy Materials College of Chemistry and Chemical EngineeringState Key Laboratory of Processing for Non-Ferrous Metal and Featured MaterialsGuangxi University100 Daxue RoadNanning530004China Institute for Structure and Function and Department of Physics Chongqing UniversityChongqing400030China

Exploitation of oxygen evolution reaction(OER)and urea oxidation reaction(UOR)catalysts with high activity and stability at large current density is a major challenge for energy-saving H_(2) production in water ***,we use the pyridinic-N doping carbon layers coupled with tensile strain of FeNi alloy activated by NiFe_(2)O_(4)(FeNi/NiFe_(2)O_(4)@NC)for efficiently increasing the performance of water and urea *** to the tensile strain effect on FeNi/NiFe_(2)O_(4)@NC,it provides a favorable modulation on the electronic properties of the active center,thus enabling amazing OER(η_(100)=196 mV)and UOR(E_(10)=1.32 V)intrinsic ***,the carbon-coated layers can be used as armor to prevent FeNi alloy from being corroded by the electrolyte for enhancing the OER/UOR stability at large current density,showing high industrial *** work thus provides a simple way to prepare high-efficiency catalyst for activating water and urea oxidation.

关键词： Carbon-encapsulated Tensile strain Catalyst Oxygen evolution reaction Urea oxidation reaction