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Valley dynamics of different excitonic states in monolayer WSe_(2)grown by molecular beam epitaxy

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Journal of Semiconductors 2022年第8期43卷 33-40页

作者： shengmin hu Jialiang Ye Ruiqi Liu Xinhui Zhang State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China College of Materials Science and Opto-electronic Technology University of Chinese Academy of SciencesBeijing 100049China

Monolayer transition-metal dichalcogenides possess rich excitonic physics and unique valley-contrasting optical selection rule,and offer a great platform for long spin/valley lifetime engineering and the associated spin/valleytronics exploration.Using two-color time-resolved Kerr rotation and time-resolved reflectivity spectroscopy,we investigate the spin/valley dynamics of different excitonic states in monolayer WSe_(2)grown by molecular beam epitaxy.With fine tuning of the photon energy of both pump and probe beams,the valley relaxation process for the neutral excitons and trions is found to be remarkably different-their characteristic spin/valley lifetimes vary from picoseconds to nanoseconds,respectively.The observed long trion spin lifetime of>2.0 ns is discussed to be associated with the dark trion states,which is evidenced by the photon-energy dependent valley polarization relaxation.Our results also reveal that valley depolarization for these different excitonic states is intimately connected with the strong Coulomb interaction when the optical excitation energy is above the exciton resonance.

关键词： TMDCs excitons valley polarization lifetime two-color time-resolved Kerr rotation spectroscopy

Influencing Factors on Cardiovascular Health in China

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Journal of Geriatric Cardiology 2024年第1期21卷 4-33页

作者： Sheng-Shou hu 无 Fuwai Hospital Chinese Academy of Medical Sciences BeijingChina the Writing Committee of the Report on Cardiovascular Health and Diseases in China

The Annual Report on Cardiovascular Health and Diseases in China(2022)intricate landscape of cardiovascular health in China.This is the first section of the report,which dissects influential factors across diverse domains.The investigation identifies tobacco use as a paramount concern,portraying China as the global epicenter of tobacco consumption.Cigarette smoking,exacerbated by second-hand smoke exposure,emerges as a critical and preventable risk factor,contributing to a surge in attributable deaths over the past three decades.In the realm of dietary nutrition,the study discerns an overall improvement,yet discerns worrisome deviations,notably an escalating fat intake surpassing recommended guidelines.The shifting dietary structure reveals diminished consumption of cereals and vegetables juxtaposed with an uptick in animal foods,while excessive intake of cooking oil and salt persists,straying substantially from endorsed levels.The exploration of physical activity patterns unfolds a nuanced narrative.Varied trends are observed among students,with concerns arising from sedentary behaviors and inadequate adherence to recommended guidelines.The analysis spans a trajectory of declining physical activity in Chinese adults,coupled with an alarming surge in sedentary leisure time,ultimately linking these factors to heightened risks of cardiovascular diseases and increased adiposity.An examination of overweight and obesity trends uncovers a relentless upward trajectory,projecting substantial prevalence by 2030.Noteworthy prevalence rates underscore the imperative for targeted interventions to curtail this burgeoning health crisis,with the anticipated prevalence extending to nearly two-thirds of the adult population.Psychological factors,notably depression,constitute an integral facet of cardiovascular health.Prevalence rates among patients with coronary artery disease and acute myocardial infarction underscore the intricate interplay between mental health and cardiovascular outcomes.Additionally,persistent depressive sym

关键词： Influencing smoke linking

Unusual Single Electron Transfer Reactions between Alkenes and Iodine Electrophiles

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Chinese Journal of Chemistry 2024年第5期42卷 471-477页

作者： Zhengzhao Lou Jingyu hu Chuanfa Ni Xiu Wang Jinbo hu Key Laboratory of Organofluorine Chemistry Shanghai Institute of Organic ChemistryUniversity of Chinese Academy of SciencesChinese Academy of Sciences345 Ling Ling RoadShanghai200032 China School of Physical Science and Technology ShanghaiTech University100 Haike RoadShanghai201210 China

The electrophilic addition to an alkene with an electrophile has been widely studied and applied in organic synthesis.The organic chemistry textbook describes the classical reaction between an alkene and an iodine electrophile(such as elemental iodine and N-iodosuccinimide(NIS))as a typical ionic reaction,in which an iodonium ion is formed and then attacked by a nucleophile.However,in this article,we report a new and unusual reaction mode between an alkene and NIS;that is,a single electron transfer(SET)process occurs between these two reactants by forming an electron-donor acceptor complex.Not only does this unusual single electron transfer reaction between an alkene and NIS add fundamentally important knowledge to organic chemistry,it also provides a valuable synthetic method as the new SET reaction mode with opposite regioselectivity as compared with the traditional ionic mode.

关键词： Electrophilic addition Radical ions Reaction mechanisms Alkenes Fluorine

A Review of Contact Electrification at Diversified Interfaces and Related Applications on Triboelectric Nanogenerator

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Nano-Micro Letters 2024年第1期16卷 106-130页

作者： Jun hu Mitsumasa Iwamoto Xiangyu Chen CAS Center for Excellence in Nanoscience Beijing Institute of Nanoenergy and NanosystemsChinese Academy of SciencesBeijing 100083People’s Republic of China School of Nanoscience and Engineering University of Chinese Academy of SciencesBeijing 100049People’s Republic of China Department of Physical Electronics Tokyo Institute of Technology2‑12‑1 S3‑33 O‑OkayamaMeguro‑KuTokyo 152‑8552Japan

The triboelectric nanogenerator(TENG)can effectively collect energy based on contact electrification(CE)at diverse interfaces,including solid–solid,liquid–solid,liquid–liquid,gas–solid,and gas–liquid.This enables energy harvesting from sources such as water,wind,and sound.In this review,we provide an overview of the coexistence of electron and ion transfer in the CE process.We elucidate the diverse dominant mechanisms observed at different interfaces and emphasize the interconnectedness and complementary nature of interface studies.The review also offers a comprehensive summary of the factors influencing charge transfer and the advancements in interfacial modification techniques.Additionally,we highlight the wide range of applications stemming from the distinctive characteristics of charge transfer at various interfaces.Finally,this review elucidates the future opportunities and challenges that interface CE may encounter.We anticipate that this review can offer valuable insights for future research on interface CE and facilitate the continued development and industrialization of TENG.

关键词： Contact electrification Interfaces Triboelectric nanogenerators Diversified applications

R-matrix for the 8-Dimensional Spin Representation of Uq(so7)

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Acta Mathematica Sinica,English Series 2024年第2期40卷 485-497页

作者： Hong Mei hu Nai Hong hu School of Mathematical Sciences Suzhou University of Science and TechnologySuzhou 215009P.R.China School of Mathematical Sciences MOE Key Laboratory of Mathematics and Engineering Applications&Shanghai Key Laboratory of PMMPEast China Normal UniversityShanghai 200241P.R.China

The purpose of the paper is to describe the solution to the quantum Yang-Baxter equation associated with the 8-dimensional spin representation Tsp of Uq(so7).The self-duality of Tsp and the symmetry of the corresponding braiding matrix are proved.Also,the minimal polynomial of the braiding R-matrix of Tsp is presented explicitly in an ingenious method by taking advantage of nice features of the spin representation Tsp.

关键词： Braiding R-matrix spin module minimal polynomial

Investigation of mechanical and electrical characteristics of selfsensing pneumatic torsional actuators

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Science China(Technological Sciences) 2024年第1期67卷 130-142页

作者： XIAO Wei hu DeAn hu GuoLiang XIAO Yihua Key Laboratory of Conveyance and Equipment Ministry of EducationEast China Jiaotong UniversityNanchang 330013China Key Laboratory of Advanced Design and Simulation Techniques for Special Equipment Ministry of EducationHunan UniversityChangsha 410082China

Soft pneumatic actuators are one of the most promising actuation for soft robots,and great achievements have been obtained.But it remains challenging to endow sensing capabilities to pneumatic actuators,especially for the sensing ability originating directly from the actuator architecture.Herein,a self-sensing pneumatic torsional actuator(SPTA)is designed based on the electromagnetic induction effect and magnetically responsive materials.The SPTA can generate feedback voltage and current with the deformation,in which the sensing function comes from its inherent structure.To investigate the mechanical and electrical characteristics,an experimental platform and a finite element model are established,respectively.We find that the torsion angle and output torque increase in nonlinear with the actuating pressure.The maximum torsion angle is 66.35°,which is 84.34%of that for the actuator fabricated by pure rubber.The maximum output torque(24.9 N mm)improves by 23.19%compared with the actuator made by pure rubber.As regards the electrical characteristics,the maximum feedback voltage and current are 2.90μV and 29.50 nA when the SPTA is actuated by a pressure of−40 kPa.We also demonstrate that the relationship between the torsion angle and the magnetic flux change is approximately linear.Finally,the number of turns of wires,magnetic powders contents,and magnetic direction on the feedback voltage and current are studied.Results show that the feedback voltage and current can be enhanced by increasing the number of turns and magnetic powders contents.We envision that the SPTA would be promising for soft robots to realize their accuracy control and intelligentization.

关键词： pneumatic torsional actuators self-sensing feedback voltage finite element modeling soft robots

Effect of CO_(2) Opposing Multiple Jets on Thermoacoustic Instability and NO_(x) Emissions in a Lean-Premixed Model Combustor

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Journal of Thermal Science 2024年第1期33卷 207-221页

作者： ZHOU Hao hu Liubin Institute for Thermal Power Engineering State Key Laboratory of Clean Energy UtilizationZhejiang UniversityHangzhou 310027China

This paper experimentally studied the effect of CO_(2) opposing multiple jets on the thermoacoustic instability and NO_(x) emissions in a lean-premixed model combustor.The feasibility was verified from three variables:the CO_(2) jet flow rate,hole numbers,and hole diameters of the nozzles.Results indicate that the control effect of thermoacoustic instability and NO_x emissions show a reverse trend with the increase of open area ratio on the whole,and the optimal jet flow rate range is 1-4 L/min with CO_(2) opposing multiple jets.In this flow rate range,the amplitude and frequency of the dynamic pressure and heat release signals CH~* basically decrease as the CO_(2) flow rate increases,which avoids high-frequency and high-amplitude thermoacoustic instability.The amplitude-damped ratio of dynamic pressure and CH*can reach as high as 98.75% and 93.64% with an optimal open area ratio of 3.72%.NO_(x) emissions also decrease as the jet flow rate increases,and the maximum suppression ratio can reach 68.14%.Besides,the flame shape changes from a steep inverted "V" to a more flat "M",and the flame length will become shorter with CO_(2) opposing multiple jets.This research achieved the synchronous control of thermoacoustic instability and NO_(x) emissions,which could be a design reference for constructing a safer and cleaner combustor.

关键词： thermoacoustic instability lean-premixed model combustor CO_(2)opposing multiple jets open area ratio NO_(x)emissions

Multi-Axis Attention With Convolution Parallel Block for Organoid Segmentation

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IEEE/CAA Journal of Automatica Sinica 2024年第5期11卷 1295-1297页

作者： Pengwei hu Xun Deng Feng Tan Lun hu Xinjiang Technical Institute of Physics and Chemistry Chinese Academy of SciencesUrumqi 830011 University of Chinese Academy of Sciences Beijing 100049 Xinjiang Laboratory of Minority Speech and Language Information Processing Urumqi 830011China Merck KGaA Darmstadt 64293Germany

Dear Editor,This letter presents an organoid segmentation model based on multi-axis attention with convolution parallel *** adeptly captures dynamic dependencies within bright-field microscopy images,improving global ... 详细信息

关键词： letter convolution organo

Mapping out the reaction network of humin formation at the initial stage of fructose dehydration in water

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Green Energy & Environment 2024年第6期9卷 1016-1026页

作者： Xing Fu Yexin hu Ping hu hui Li Shuguang Xu Liangfang Zhu Changwei hu Key Laboratory of Green Chemistry and Technology Ministry of EducationCollege of ChemistrySichuan UniversityChengduSichuan610064China State Key Laboratory of Southwestern Chinese Medicine Resources Innovative Institute of Chinese Medicine and PharmacyChengdu University of Traditional Chinese MedicineChengduSichuan611137China

The formation of humins hampers the large-scale production of 5-hydroxymethylfurfural(HMF)in biorefinery.Here,a detailed reaction network of humin formation at the initial stage of fructose-to-HMF dehydration in water is delineated by combined experimental,spectroscopic,and theoretical studies.Three bimolecular reaction pathways to build up soluble humins are demonstrated.That is,the intermolecular etherification of β-furanose at room temperature initiates the C12 path,whereas the C-C cleavage of a-furanose at 130-150℃ leads to C11 path,and that of open-chain fructose at 180℃ to C11' path.The successive intramolecular dehydrations and condensations of the as-formed bimolecular intermediates lead to three types of soluble humins.We show that the C12 path could be restrained by using HCl or AlCl_(3) catalyst,and both the C12 and C110 paths could be effectively inhibited by adding THF as a co-solvent or accelerating heating rate via microwave heating.

关键词： Carbohydrates 5-hydroxymethylfurfural Reaction network Soluble humins Tautomer