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A Facile Strategy for Intrinsic Low-Dk and Low-Df Polyimides Enabled by Spirobifluorene Groups

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高分子科学：英文版 2023年第2期41卷 288-296页

作者： Wan-Yi Tan Ling-Feng Jian Wei-Peng Chen yong-Wen Zhang Xiao-Chuang Lu Wan-Jun Huang Ji-Sheng Zhang Jing-Wu Wu Jun-Li Feng Yi-Dong Liu Ting-Ting Cui yong-gang min Guangdong University of Technology(GDUT) Guangzhou510006China Huimai Materials Technology(Guangdong)Co. Ltd.Foshan528200China Shenzhen Customs Industrial Product Inspection Technology Center Shenzhen518026China

Modified polyimides(MPIs)show great potential towards 5G communication applications,due to its excellent thermal stability,mechanical property and chemical stability as compared to most of polymers.Introducing fluoride groups or porous structure is favorable to ultra-low dielectric constant(D_(k))and dielectric loss(D_(f)).However,the cost of the fluorinated MPIs is high and their synthetic processes are complicated,and porous MPIs suffer poor mechanical properties.Also,increasing the fraction of free volume is a very effective way to lower D_(k)through introducing more ultra-low-D_(k)air component.However,most of this kind of MPIs lag far behind the fluorinated MPIs and the porous MPIs in terms of ultra-low D_(f),hindering the application of MPIs in high-speed communication devices.Thus,it is highly desirable to develop intrinsic ultra-low-D_(k)/D_(f)MPIs at high frequency with less fluoric groups and nonporous structure.Herein,we introduce a facile and effective strategy to lower D_(k)and D_(f)through introducing rigid and large sterically hindered aromatic groups into MPIs.On the one hand,their large steric hindrance effect leads to low D_(k)by increasing intrinsic free volume.On the other hand,the resulting highly stiff polymer chain and strong intermolecular interaction are favorable to reduce D_(f)by inhibiting dipole orientations.Based on this strategy,the spirobifluorene groups are preferred.The as-prepared MPIs show excellent dielectric performance with low D_(k)of 2.74–2.76 and low D_(f)of 0.00599 at 10 GHz,to some extent,exceeding the multiple fluorinated MPI with D_(k)/D_(f)of 2.67/0.00663 at 10 GHz.

关键词： Polyimide High speed communication Low dielectric constant Low dielectric loss

Ligand-controlled NiH-catalyzed regiodivergent hydroalkylation of 2-alkenylazaarenes

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Science China Chemistry 2024年第6期67卷 1935-1940页

作者： Ya-Ping Shao Zhuo-min Chi yong-min Liang State Key Laboratory of Applied Organic Chemistry School of Chemistry and Chemical EngineeringLanzhou UniversityLanzhou730000China

A nickel-hydride(Ni H)-catalyzed migratory and nonmigratory hydroalkylation reaction of 2-alkenyl azaarenes with alkyl iodines has been established through strategic modulation of N-or P-donor ligands.This method enables the synthesis of diverseβ-orγ-branched aromatic N-heterocycles.The mild regiodivergent protocols exhibit wide substrate scope,excellent functional tolerance,and great reaction yield with remarkable regioselectivity.Importantly,deuterium labeling studies reveal Ni H-catalyzed interrupted chain-walking mode as the mechanism behind remotedβ-selective hydroalkylation reaction—an interesting phenomenon mediated through aromatic imine directing groups.

关键词： NiH regiodivergent hydroalkylation azaarenes interrupted chain-walking

Moderate Deviations for Parameter Estimation in the Fractional Ornstein–Uhlenbeck Processes with Periodic Mean

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Acta Mathematica Sinica,English Series 2024年第5期40卷 1308-1324页

作者： Hui JIANG Shi min LI Wei gang WANG School of Mathematics Nanjing University of Aeronautics and AstronauticsNanjing 210016P.R.China The People's Bank of China Operations Ofice of Nanjing Branch Nanjing 210016P.R.China School of Statistics and Mathematics Zhejiang Gongshang UniversityHangzhou 310018P.R.China

In this paper,we study the asymptotic properties for the drift parameter estimators in the fractional Ornstein-Uhlenbeck process with periodic mean function and long range dependence.The Cremér-type moderate deviatio... 详细信息

关键词： Cramér-type moderate deviation fractional Ornstein-Uhlenbeck process parameter estimation multiple Wiener-Ito integrals

Machine learning will revolutionize perovskite solar cells

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The Innovation 2024年第3期5卷 13-14页

作者： Ziming Chen Shuang Pan Jing Wang yonggang min Yihuang Chen Qifan Xue State Key Laboratory of Luminescent Materials and Devices Institute of Polymer Optoelectronic Materials and DevicesSchool of Materials Science and EngineeringSouth China University of TechnologyGuangzhou 510640China College of Chemistry and Materials Engineering Wenzhou UniversityWenzhou 325035China School of Materials and Energy Guangdong University of TechnologyGuangzhou 510006China

With the emergence of ChatGPT and its rapid iteration speed,artificial intelligence(AI)has undoubtedly become the driving force behind a new wave of technological revolution.After more than half a century of development,AI has become akin to the steam engine of the Industrial Revolution,propelling humanity into the era of intelligence.The global industrial chain has also recognized that AI technology will spearhead a new wave of industrial transformation and development.Machine learning(ML),driven by data,abstracts real-life problems into mathematical problems and solves them using computers.It is currently the mainstream method for addressing many AI problems.Perovskite solar cells(PSCs)are currently the focus of researchers around the world due to their high efficiency,low cost,and simple manufacturing process.They are considered the most promising third-generation solar cell for commercialization.In 2011,the United States proposed the Materials Genome Initiative(MGI).The main idea is to utilize the“trinity”approach of computing,data,and experiments to transform the conventional“trial and error”model of materials research and development,which relies heavily on experience and experimentation,in order to enhance the quality,speed of discovery,development,production,and application of new materials.Driven by the MGI,research on the combination of ML with great application potential and rapidly developing PSC(ML&PSC)emerged(Figure 1).

关键词： utilize Figure doubt

Normalized Solution for p-Kirchhoff Equation with a L2-supercritical Growth

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Acta Mathematicae Applicatae Sinica 2024年第2期40卷 414-429页

作者： Zhi-min REN yong-yi LAN School of Sciences Jimei UniversityXiamen 361005China

In this paper,we investigate the following p-Kirchhoff equation{∫R^(N)|u|^(2)dx=ρ,(a+b)∫RN(|Δu}^(p)+|u|^(p))dx)(-Δpu+|u|^(p-2u)=|u|^(s-2)u+μu,x∈R^(N),where a>0,b≥0,p>0 are constants,constants,p*=N-P/Np is the ... 详细信息

关键词： p-Kirchhoff equation normalized solution mountain-pass lemma

Thermodynamic model for deoxidation of liquid steel considering strong metal-oxygen interaction in the quasichemical model framework

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International Journal of minerals,Metallurgy and Materials 2024年第5期31卷 988-1002页

作者： yong-min Cho Youn-Bae Kang Graduate Institute of Ferrous and Eco Materials Technology Pohang University of Science and TechnologyPohangKyungbuk37673Rep.of Korea N.EX.T Hub POSCO HoldingsPohangKyungbuk37673Rep.of Korea Department of Materials Science and Engineering Pohang University of Science and TechnologyPohangKyungbuk37673Rep.of Korea

Herein,a thermodynamic model aimed at describing deoxidation equilibria in liquid steel was developed.The model provides explicit forms of the activity coefficient of solutes in liquid steel,eliminating the need for the minimization of internal Gibbs energy preliminarily when solving deoxidation equilibria.The elimination of internal Gibbs energy minimization is particularly advantageous during the coupling of deoxidation equilibrium calculations with computationally intensive approaches,such as computational fluid dynamics.The model enables efficient calculations through direct embedment of the explicit forms of activity coefficient in the computing code.The proposed thermodynamic model was developed using a quasichemical approach with two key approximations:random mixing of metallic elements(Fe and oxidizing metal) and strong nonrandom pairing of metal and oxygen as nearest neighbors.Through these approximations,the quasichemical approach yielded the activity coefficients of solutes as explicit functions of composition and temperature without requiring the minimization of internal Gibbs energy or the coupling of separate programs.The model was successfully applied in the calculation of deoxidation equilibria of various elements(Al,B,C,Ca,Ce,Cr,La,Mg,Mn,Nb,Si,Ti,V,and Zr).The limitations of the model arising from these assumptions were also discussed.

关键词： deoxidation equilibria thermodynamics quasichemical approach computational fluid dynamics

Concise extraction and characterization of the pore-throat network in unconventional hydrocarbon reservoirs: A new perspective

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Petroleum Science 2024年第3期21卷 1474-1487页

作者： Shu-Heng Du yong-min Shi State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences School of Engineering Science University of Chinese Academy of Sciences School of Earth and Space Sciences Peking University

In this study, a new image-based method for the extraction and characterization of pore-throat network for unconventional hydrocarbon storage and exploitation is proposed. “Pore-throat solidity”, which is analogous to particle solidity, and a new method for automatic identification of pores and throats in tight sandstone oil reservoirs are introduced. Additionally, the “pore-throat combination” and “pure pore” are defined and distinguished by drawing the cumulative probability curve of the pore-throat solidity and by selecting an appropriate cutoff point. When the discrete grid set is recognized as a pore-throat combination, Legendre ellipse fitting and minimum Feret diameter are used. When the pore and throat grid sets are identified as pure pores, the pore diameter can be directly calculated. Using the new method, the analytical results for the physical parameters and pore radius agree well with most prior studies. The results comparing the maximum ball and the new model could also prove the accuracy of the latter's in micro and nano scales. The new model provides a more practical theoretical basis and a new calculation method for the rapid and accurate evaluation of the complex processes of oil migration.

关键词： Hydrocarbon exploitation Pore Throat Porous media Identification

Apically guiding electron/mass transfer reaction induced by Ag/FeNx Mott-Schottky effect within a hollow star reactor toward high performance zinc-air batteries

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Journal of Energy Chemistry 2024年第8期95卷 106-116页

作者： Kaixiang Shi Kaixin Wang Tong Li Junhao Li Jie Ren Xu Li yonggang min Zhouguang Lu Wei Tan Quanbing Liu Guangdong Provincial Laboratory of Chemistry and Fine Chemical Engineering Jieyang Center(Rongjiang Laboratory) Guangdong University of Technology Guangzhou Key Laboratory of Clean Transportation Energy Chemistry Guangdong Provincial Key Laboratory of Plant Resources Biorefinery School of Chemical Engineering and Light Industry Guangdong University of Technology Key Laboratory of Electrochemical Energy Storage and Energy Conversion of Hainan Province School of Chemistry and Chemical Engineering Hainan Normal University School of Materials and Energy Guangdong University of Technology Department of Materials Science and Engineering Southern University of Science and Technology

The disparity in the transfer of carriers（electrons/mass） during the reaction in zinc-air batteries（ZABs）results in sluggish kinetics of the oxygen reduction reaction（ORR） and oxygen evolution reaction（OER）,along with elevated overpotentials,thereby imposing additional constraints on its utilization.Therefore,the pre-design and target-development of inexpensive,high-performance,and long-term stable bifunctional catalysts are urgently needed.In this work,an apically guiding dual-functional electrocatalyst（Ag-FeNx-N-C） was prepared,in which a hierarchical porous nitrogen-doped carbon with three-dimensional（3D） hollow star-shaped structure is used as a substrate and high-conductivity Ag nanoparticles are coupled with iron nitride（FeNx） nanoparticles.Theoretical calculations indicate that the Mott-Schottky heterojunction as an inherent electric field comes from the two-phase bound of Ag and FeNx,of which electron accumulation in the FeNxphase region and electron depletion in the Ag phase region promote orientated-guiding charge migration.The effective modulation of local electronic structures felicitously reforms the d-band electron-group distribution,and intellectually tunes the masstransfer reaction energy barriers for both ORR/OER.Additionally,the hollow star-s haped hierarchical porous structure provides an apical region for fast mass transfer.Experimental results show that the halfwave potential for ORR is 0.914 V,and the overpotential for OER is only 327 mV at 10 mA cm-2.A rechargeable ZAB with Ag-FeNx-N-C as the air cathode demonstrates long-term cycling performance exceeding 1500 cycles（500 h）,with a power density of 180 mW cm-2.Moreover,when employing AgFeNx-N-C as the air cathode,flexible ZABs demonstrate a notable open-circuit voltage of 1.42 V and achieve a maximum power density of 65.6 mW cm-2.Ag-FeNx-N-C shows guiding electron/mass transfer route and apical reaction microenvironment for the electrocatalyst architecture in the exploration prospects of ZABs.

关键词： Apically guiding effect Bifunctional catalysis Hollow star structure Mott-Schottky effect Zinc-air batteries

Environmental enrichment in combination with Bifidobacterium breve HNXY26M4 intervention amplifies neuroprotective benefits in a mouse model of Alzheimer's disease by modulating glutamine metabolism of the gut microbiome

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Food Science and Human Wellness 2024年第2期13卷 982-992页

作者： Guangsu Zhu min Guo Jianxin Zhao Hao Zhang gang Wang Wei Chen State Key Laboratory of Food Science and Resources Jiangnan UniversityWuxi 214122China School of Food Science and Technology Jiangnan UniversityWuxi 214122China (Yangzhou)Institute of Food Biotechnology Jiangnan UniversityYangzhou 225004China National Engineering Center of Functional Food Jiangnan UniversityWuxi 214122China

The gut microbiota-brain axis has emerged as a novel target for Alzheimer's disease(AD),a neurodegenerative disease characterised by behavioural and cognitive impairment.However,most previous microbiome-based intervention studies have focused on single factors and yielded only modest cognitive improvements.Here,we proposed a multidomain intervention strategy that combined Bifidobacterium breve treatment with environmental enrichment(EE)training.In this study,we found that compared with EE or B.breve treatment alone,B.breve intervention combined with EE amplified its neuroprotective effects on AD mice,as reflected by improved cognition,inhibited neuroinflammation and enhanced synaptic function.Moreover,using microbiome and metabolome profiling,we found that the combination of B.breve and EE treatment restored AD-related gut microbiota dysbiosis and reversed microbial metabolite changes.Finally,by integrating behavioural and neurological data with metabolomic profiles,we revealed that the underlying mechanism may involve the modulation of microbiota-derived glutamine metabolism via gut-brain interactions.Collectively,combined B.breve intervention with EE treatment can alleviate AD-related cognitive impairment and improve brain function by regulating glutamine metabolism of the gut microbiome.Our findings provide a promising multidomain intervention strategy,with a combination of dietary microbiome-based and lifestyle-targeted interventions,to promote brain function and delay the progression of AD.

关键词： Alzheimer’s disease Bifidobacterium breve Environmental enrichment Glutamine metabolism Microbiota-gut-brain axis