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Diophantine equations and Fermat's last theorem for multivariate(skew-)polynomials

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Applied Mathematics(A Journal of Chinese Universities) 2024年第1期39卷 159-173页

作者： PAN Jie JIA Yu-ming LI Fang school of Mathematical Sciences Zhejiang UniversityHangzhou 310058China Henan experimental High school Zhengzhou 450003China

Fermat’s Last Theorem is a famous theorem in number theory which is diﬃcult to prove.However,it is known that the version of polynomials with one variable of Fermat’s Last Theorem over C can be proved very concisely.The aim of this paper is to study the similar problems about Fermat’s Last Theorem for multivariate(skew)-polynomials with any characteristic.

关键词： Fermat's last theorem polynomial ring skew polynomial ring

Effect of wire mesh casing treatment on axial compressor performance and stability

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Chinese Journal of Aeronautics 2024年第3期37卷 60-76页

作者： Ming ZHANG Jiaming ZHANG Jiahao HU Xu DONG Dakun SUN Xiaofeng SUN school of Energy and Power Engineering Beihang UniversityBeijing 100191China Beihang Hangzhou Innovation Institute yuhang Hangzhou 310023China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 100191China

In this paper,a kind of Wire Mesh Casing Treatment(WMCT)is proposed to improve the stable operating range of the compressor.In contrast to the traditional circumferential groove,as for WMCT,a layer of wire mesh is laid on the surface of the circumferential groove.Parametric studies were conducted on the low-speed axial flow compressor,including the groove width,axial location,and mesh count.The optimum axial location for WMCT is related to its groove width.A higher wire mesh count results in a smaller compressor stall margin improvement.Steady simulations were carried out to study the effect of WMCT on the flow structure of the compressor.The wire mesh in the WMCT has a certain flow resistance,which restricts the flow into and out of the groove.Due to the WMCT,the flow parameter in the tip region of the rotor is less sensitive to changes in the operating conditions of the compressor.The WMCT causes the rotor tip blade loading to shift backward,inhibiting the formation of spill forward of the leakage flow,and thus improving the stability of the compressor.The flow resistance on the groove surface is a new degree-of-freedom for the casing treatment designer.

关键词： Axial compressor Wire mesh casing treatment Tip clearance flow Stall margin Blade loading

Hole-Doped Nonvolatile and Electrically Controllable Magnetism in van der Waals Ferroelectric Heterostructures

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Chinese Physics Letters 2024年第5期41卷 107-119页

作者：姜新新王智宽李冲孙雪莲杨磊李冬梅崔彬刘德胜 school of Physics National Demonstration Center for Experimental Physics EducationShandong UniversityJinan 250100China school of Physics and Microelectronics Zhengzhou UniversityZhengzhou 450001China

Electrical control of magnetism in van der Waals semiconductors is a promising step towards development of two-dimensional spintronic devices with ultralow power consumption for processing and storing information.Here, we propose a design for two-dimensional van der Waals heterostructures(vdWHs) that can host ferroelectricity and ferromagnetism simultaneously under hole doping. By contacting an In Se monolayer and forming an InSe/In_(2)Se_(3) vd WH, the switchable built-in electric field from the reversible out-of-plane polarization enables robust control of the band alignment. Furthermore, switching between the two ferroelectric states(P_↑ and P_↓)of hole-doped In_(2)Se_(3) with an external electric field can interchange the ON and OFF states of the nonvolatile magnetism. More interestingly, doping concentration and strain can effectively tune the magnetic moment and polarization energy. Therefore, this provides a platform for realizing multiferroics in ferroelectric heterostructures,showing great potential for use in nonvolatile memories and ferroelectric field-effect transistors.

关键词： polarization ferroelectric doping

Investigation of surface textures deterioration on pavement skid-resistance using hysteresis friction models and numerical simulation method

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Friction 2024年第4期12卷 745-779页

作者： Haoyuan LUO Siyu CHEN Leyi ZHU Xiyin LIU Yangzezhi ZHENG Runming ZHAO Xiaoming HUANG school of Transportation Southeast UniversityNanjing 211189China National Demonstration Center for experimental Education of Road and Traffic Engineering Southeast UniversityNanjing 211189China

Many rubber friction theories or some method combined theories and field-experiments are employed to evaluate the pavement skid-resistance deterioration due to the evolution of surface textures.However,these methods are difficult to be implemented in the analysis of situations with multi-factor coupling and some extreme conditions.This study developed a framework to evaluate the skid-resistance deterioration of asphalt pavements.In this framework,the portable laser scanning was used to create the digital worn pavement model,and a hydroplaning finite element(FE)model for these digital worn pavements was constructed to evaluate coupling effects of the texture evolution and factors of slip ratio,slip angle,velocity and water film on braking-cornering characteristics of tire.In this study,the deterioration of skid-resistance of five typical asphalt pavements due the surface texture wear was systematically investigated by this framework.Compared with previous works,this study established the rubber friction models for each digital worn pavement considering the energy hysteresis of rubber and the power spectrum density of surface texture.And the rubber friction model was used to define the interaction behaviors between the tire and corresponding wore pavements in the FE hydroplaning model,rather than using an empirical friction model or a fixed friction coefficient.

关键词： worn pavement skid-resistance friction coefficient textures evolution water film computer numerical simulation

Consequences of early life stress on the structure and function of the adult mouse retina

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Neural Regeneration Research 2024年第1期19卷 150-151页

作者： Juan S.Calanni Ruth E.Rosenstein Laboratory of Retinal Neurochemistry and experimental Ophthalmology Department of Human BiochemistrySchool of Medicine/CEFyBOUniversity of Buenos Aires/CONICETBuenos AiresArgentina

Early-life stress(ELS)refers to a period of environmental/social deprivation,physica l,sexual or emotional abuse,neglect,severe and/or chronic trauma in the prenatal/early postnatal stage,which is closely related to many adverse psychiatric disorders later in life,such as depressive disorder,substance abuse,dysthymia,panic,anxiety,and suicidal behavior in adulthood(Waters and Gould,2022).

关键词： stress life Gould

Working toward an integrated plasticity/network framework for repetitive transcranial magnetic stimulation to inform tailored treatments

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Neural Regeneration Research 2024年第7期19卷 1423-1424页

作者： Jessica Moretti Jennifer Rodger experimental and Regenerative Neurosciences School of Biological SciencesUniversity of Western AustraliaCrawleyWAAustralia Brain Plasticity Lab Perron Institute for Neurological and Translational ScienceNedlandsWAAustralia

Non-invasive brain stimulation techniques(NIBS),including repetitive transcranial magnetic stimulation(rTMS) and transcranial electric stim ulation(tES),are increasingly being adopted clinically for treatment of neuropsychiatric and neurological disorders,albeit with varying success.The rationale behind the use of NIBS has historically been that stim ulation techniques modulate neuronal activity in the targeted region and consequently induce plasticity which can lead to therapeutic outcomes.

关键词： stimulation transcranial treatment

Technologies and studies of gas exchange in two-stroke aircraft piston engine:A review

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Chinese Journal of Aeronautics 2024年第1期37卷 24-50页

作者： Yu ZHOU Xueyu LI Shuiting DING Shuai ZHAO Kun ZHU Longtao SHAO Farong DU Gerui WANG Zheng XU Research Institute of Aero-Engine Beihang UniversityBeijing 100191China Aircraft/Engine Integrated System Safety Beijing Key Laboratory Beijing 100191China school of Transportation Science and Engineering Beihang UniversityBeijing 100191China Civil Aviation University of China Tianjin 300300China Aero Engine Academy of China Beijing 101304China school of Energy and Power Engineering Beihang UniversityBeijing 100191China Beihang Hangzhou Innovation Institute yuhang Hangzhou 310052China

The in-cylinder gas exchange process is crucial to the power performance of two-stroke aircraft piston engines,which is easily influenced by complex factors such as high-altitude performance variation and in-cylinder flow characteristics.This paper reviews the development history and characteristics of gas exchange types,as well as the current state of theory and the validation methods of gas exchange technology,while also discusses the trends of cutting-edge technologies in the field.This paper provides a theoretical foundation for the optimization and engineering design of gas exchange systems and,more importantly,points out that the innovation of gas exchange types,the modification of theoretical models,and the technology of variable airflow organization are the key future research directions in this field.

关键词： Aircraft piston engine Aircraft power systems Gas exchange High-altitude performance In-cylinder flow Two-stroke Unmanned Aerial Vehicles(UAVs)

PbrARF4 contributes to calyx shedding of fruitlets in ‘Dangshan Suli’ pear by partly regulating the expression of abscission genes

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Horticultural Plant Journal 2024年第2期10卷 341-354页

作者： Guoling Guo Pengfei Wei Tao Yu Haiyan Zhang Wei Heng Lun Liu Liwu Zhu Bing Jia school of Horticulture Anhui Agricultural UniversityHefeiAnhui 230036China Huayuan Foreign Language school Zhejiang Normal UniversityJinhuaZhejiang 322100China Agricultural experimental Center of Guiyang Guiyang Agriculture and Rural BureauGuiyangGuizhou 550018China

Fruitlet calyx shedding in pear plants is apparently regulated via numerous pathways that involve both environmental triggers and phytohormones cues such as auxin. In this study, we found at 10 days after full bloom (DAFB) higher levels of indoleacetic acid (IAA) and tryptophan (Trp) in calyx persistence fruitlet (CPF) than calyx shedding fruitlet (CSF) ofDanshan Suli’ pear (Pyrus bretschneideri Rhed.). Consisting with this, the activity of indolealdehyde oxidase (IAAIdO), which promotes IAA synthesis, was remarkably increased, and that of peroxidase(POD), which degrades IAA, dropped markedly in CPF but not in CSF. Further, qRT-PCR results revealed that most of 31 PbrARFs (encoding auxin response factors) in Pyrus bretschneideri were highly expressed in CPF, whereas PbrARF4, PbrARF24 and PbrARF26 were significantly downregulated in CPF vis-a-vis CSF. Phylogenetic analysis revealed that 6 PbrARFs clustered in the group III, where PbrARF4 showed the closest affinity with AtARF1 that promotes organ abscission, indicating a putative role of PbrARF4 in mediating the process of calyx shedding in pear. In fact, the ectopic overexpression of PbrARF4 in Solanum lycopersicum resulted in an earlier-formed and deeper abscission layer (AL) in the transgenic plants, whose calyxes were more prone to wilt at the mature red stage (MR) compared with the control plants (wild-type). More importantly, expression levels of the abscission genes SILS and Sl Cel2 in transgenic plants overexpressing PbrARF4 were significantly upregulated in comparation with the WT, whereas those of Sl BI and Sl TAPG2 were considerably inhibited. Further, PbrJOINTLESS and PbrIDA,the two genes related to calyx shedding in pear, were up-regulated more in CSF than CPF. The findings contribute to a better understanding of PbrARFs involved in fruitlet calyx shedding of pear, which could prove beneficial to improving the quality of pear fruit.

关键词： Pear Pyrus bretschneideri Rehd Calyx shedding IAA PbrARF4 Abscission genes

Adverse effects of exposure to fine particles and ultrafine particles in the environment on different organs of organisms

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Journal of Environmental Sciences 2024年第1期135卷 449-473页

作者： Jianwei Zhang Zhao Chen Dan Shan Yang Wu Yue Zhao Chen Li Yue Shu Xiaoyu Linghu Baiqi Wang Department of Occupational and Environmental Health School of Public HealthTianjin Medical UniversityTianjin 300070China Department of Medical Tianjin Stomatological HospitalSchool of MedicineNankai UniversityTianjin 300041China Tianjin Key Laboratory of Environment Nutrition and Public HealthTianjin 300070China National Demonstration Center for experimental Preventive Medicine Education(Tianjin Medical University) Tianjin 300070China

Particulate pollution is a global risk factor that seriously threatens human health.Fine particles(FPs)and ultrafine particles(UFPs)have small particle diameters and large specific surface areas,which can easily adsorb metals,microorganisms and other pollutants.FPs and UFPs can enter the human body in multiple ways and can be easily and quickly absorbed by the cells,tissues and organs.In the body,the particles can induce oxidative stress,inflammatory response and apoptosis,furthermore causing great adverse effects.Epidemiological studies mainly take the population as the research object to study the distribution of diseases and health conditions in a specific population and to focus on the identification of influencing factors.However,the mechanism by which a substance harms the health of organisms is mainly demonstrated through toxicological studies.Combining epidemiological studies with toxicological studies will provide a more systematic and comprehensive understanding of the impact of PM on the health of organisms.In this review,the sources,compositions,and morphologies of FPs and UFPs are briefly introduced in the first part.The effects and action mechanisms of exposure to FPs and UFPs on the heart,lungs,brain,liver,spleen,kidneys,pancreas,gastrointestinal tract,joints and reproductive system are systematically summarized.In addition,challenges are further pointed out at the end of the paper.This work provides useful theoretical guidance and a strong experimental foundation for investigating and preventing the adverse effects of FPs and UFPs on human health.

关键词： Fine particles Ultrafine particles Organs Adverse effect