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Modern pollen assemblages of the surface lake sediments from the steppe and desert zones of the Tibetan Plateau

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Science China Earth Sciences 2021年第3期64卷 425-439页

作者： Feng Qin Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing100101China

Modern pollen analysis is the basis for revealing the palaeovegetation and palaeoclimate changes from fossil pollen spectra.Many studies pertaining to the modern pollen assemblages on the Tibetan Plateau have been conducted,but little attention has been paid to pollen assemblages of surface lake sediments.In this study,modern pollen assemblages of surface lake sediments from 34 lakes in the steppe and desert zones of the Tibetan Plateau are investigated and results indicate that the two vegetation zones are dominated by non-arboreal pollen taxa and show distinctive characteristics.The pollen assemblages from the desert zone contain substantially high relative abundance of Chenopodiaceae while those from the steppe zone are dominated by Cyperaceae.Pollen ratios show great potential in terms of separating different vegetation zones and to indicate climate changes on the Tibetan Plateau.The Artemisia/Chenopodiaceae ratio and arboreal/non-arboreal pollen ratio could be used as proxies for winter precipitation.Artemisia/Cyperaceae ratio and the sum of relative abundance of xerophilous elements increase with enhanced warming and aridity.When considering the vegetation coverage around the lakes,hierarchical cluster analysis suggests that the studied sites can be divided into four clusters:meadow,steppe,desert-steppe,and desert.The pollen-based vegetation classification models are established using a random forest algorithm.The random forest model can effectively separate the modern pollen assemblages of the steppe zone from those of the desert zone on the Tibetan Plateau.The model for distinguishing the four vegetation clusters shows a weaker but still valid classifying power.It is expected that the random forest model can provide a powerful tool to reconstruct the palaeovegetation succession on the Tibetan Plateau when more pollen data from surface lake sediments are included.

关键词： Modern pollen assemblage Tibetan Plateau Surface lake sediment Pollen-climate relationship Pollen-based vegetation classification model

Biome reconstruction on the Tibetan Plateau since the Last Glacial Maximum using a machine learning method

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Science China Earth Sciences 2022年第3期65卷 518-535页

作者： Feng Qin Yan ZHAO Xianyong CAO Key Laboratory ofLand Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China Alpine Paleoecology and Human Adaptation(ALPHA)Group State Key Laboratory of Tibetan Plateau Earth System Science(LATPES)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China

Historical biome changes on the Tibetan Plateau provide important information that improves our understanding of the alpine vegetation responses to climate changes.However,a comprehensively quantitative reconstruction of the historical Tibetan Plateau biomes is not possible due to the lack of quantitative methods that enable appropriate classification of alpine biomes based on proxy data such as fossil pollen records.In this study,a pollen-based biome classification model was developed by applying a random forest algorithm(a supervised machine learning method)based on modern pollen assemblages on and around the Tibetan Plateau,and its robustness was assessed by comparing its results with the predictions of the biomisation method.The results indicated that modern biome distributions reconstructed using the random forest model based on modern pollen data generally concurred with the observed zonal vegetation.The random forest model had a significantly higher accuracy than the biomisation method,indicating the former is a more suitable tool for reconstructing alpine biome changes on the Tibetan Plateau.The random forest model was then applied to reconstruct the Tibetan Plateau biome changes from 22 ka BP to the present based on 51 fossil pollen records.The reconstructed biome distribution changes on the Tibetan Plateau generally corresponded to global climate changes and Asian monsoon variations.In the Last Glacial Maximum,the Tibetan Plateau was mainly desert with subtropical forests distributed in the southeast.During the last deglaciation,the alpine steppe began expanding and gradually became zonal vegetation in the central and eastern regions.Alpine meadow occupied the eastern and southeastern areas of the Tibetan Plateau since the early Holocene,and the forest-meadow-steppe-desert pattern running southeast to northwest on the Tibetan Plateau was established afterwards.In the mid-Holocene,subtropical forests extended north,which reflected the“optimum”condition.During the late Holocene,alpine meadows and alpine s

关键词： Biome reconstruction Random forest algorithm Biomisation method Pollen data Last Glacial Maximum Tibetan Plateau

Effects and mechanisms of acupuncture on women related health

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Frontiers of Medicine 2024年第1期18卷 46-67页

作者： Huichao qin Jiaxing feng Xiaoke Wu Department of Reproductive Medicine Heilongjiang Provincial HospitalHarbin Institute of TechnologyHarbin150036China Department of Obstetrics and Gynecology First Affiliated HospitalHeilongjiang University of Chinese MedicineHarbin150040China

Globally,public health interventions have resulted in a 30-year increase in women’s life expectancy.However,women’s health has not increased when socioeconomic status is ignored.Women’s health has become a major public health concern,for those women from developing countries are still struggling with infectious and labor-related diseases,and their counterparts in developed countries are suffering from physical and psychological disorders.In recent years,complementary and alternative medicine has attracted wide attentions with regards to maintaining women’s health.Acupuncture,a crucial component of traditional Chinese medicine,has been used to treat many obstetric and gynecological diseases for thousands of years due to its analgesic and anti-inflammatory effects and its effects on stimulating the sympathetic/parasympathetic nervous system.To fully understand the mechanism through which acupuncture exerts its effects in these diseases would significantly extend the list of available interventions and would allow for more reasonable advice to be given to general practitioners.Therefore,by searching PubMed and CNKI regarding the use of acupuncture in treating obstetric and gynecological diseases,we aimed to summarize the proven evidence of using acupuncture in maintaining women’s health by considering both its effectiveness and the underlying mechanisms behind its effects.

关键词： acupuncture women health clinical efficacy mechanism

Carbon-based materials with combined functions of thermal management and electromagnetic protection: Preparation, mechanisms, properties, and applications

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Nano Research 2024年第3期17卷 883-903页

作者： Junwei Yue Yiyu feng Mengmeng qin Wei feng School of Materials Science and Engineering and Tianjin Key Laboratory of Composite and Functional Materials Tianjin UniversityTianjin 300350China

The proliferation of high-power,highly informationized,and highly integrated electronic devices and weapons equipment has given rise to increasingly conspicuous issues about electromagnetic(EM)pollution and thermal accumulation.These issues,in turn,impose constraints on the performance of such equipment and jeopardize personnel safety.Carbon materials,owing to their diverse and modifiable structures,offer adjustable thermal and electric conductivity,rendering them highly promising for applications in fields such as thermal management and EM protection which have garnered extensive research and review.The pursuit of integrated device and equipment development has elevated the demand for multifunctional materials,prompting significant research into carbon-based composite materials that include both thermal management and EM protection functionalities.Notably,there are no relevant reviews on this topic at present.Consequently,this work consolidates research findings from recent years on carbon matrix composites exhibiting dual attributes of thermal management and EM protection.These attributes include thermally conductive electromagnetic interference(EMI)shielding materials,thermally insulating EMI shielding materials,thermally conductive EM wave(EMW)absorbing materials,and thermally insulating EMW absorbing materials.The paper elucidates the fundamental principles underpinning thermal conduction,thermal insulation,EMW absorbing,and EMI shielding.Additionally,it engages in discussions surrounding areas of contention,design strategies,and the functional properties of various material designs.Ultimately,the paper concludes by presenting the challenges encountered and potential research strategies about composites endowed with both thermal management and EM protection functionalities,while also envisaging the development of novel multifunctional EM protection materials.

关键词： carbon-based composites electromagnetic interference shielding microwave absorption thermal conduction thermal insulation

Shear instability in heterogeneous nanolayered Cu/Zr composites

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Journal of Materials Science & Technology 2022年第10期105卷 81-91页

作者： Jianjun Li Feng Qin Dingshun Yan Wenjun Lu Jiahao Yao School of Mechanical and Electrical Engineering Central South UniversityChangsha 410083China State Key Laboratory of High Performance Complex Manufacturing Central South UniversityChangsha 410083China School of Materials Science and Engineering Central South UniversityChangsha 410083China Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055China Beijing Institute of Technology Chongqing Innovation Center Chongqing 401120China

Ultrastrong nanolayered metallic composites are usually subjected to low ductility due to plastic instability during deformation.Here we investigated the shear instability of a newly designed heterogeneous nanolayered Cu/Zr composites by microindentation.The heterogeneity in size was generated by inserting a few thin Cu-Zr bilayers with an individual layer thickness of 2.5-10 nm into the interface region of the Cu/Zr layered composites with an individual layer thickness of 100 nm.The microindentation tests showed that multiple shear bands appeared in the heterogeneous composite with one bilayer,whereas only a single shear band was formed in that with two or three bilayers.Most importantly,the layer strain in the multi-shear band region is much smaller than that in the single-shear band area.For example,the strain of the 100 nm layers within the shear band in the composite with one 10 nm bilayer could reach as low as 2.8,which was less than half of that in the composite with three 10 nm bilayers,i.e.,6.1.These fndings demonstrated that strain delocalization can be achieved through shear band multiplication if an appropriate number of thin bilayers were used as interlayers in the 100 nm Cu/Zr composites.Besides,compared with the homogeneous composite with an individual layer thickness of 100 nm and the bimodal composite which is composed of alternating one 100 nm Cu-Zr bilayer and two 10 nm CuZr bilayers,the heterogeneous composite with one bilayer displayed a higher strength(2.15 GPa)and a favorable resistance to strain localization.

关键词： Nanolayered metallic composites Sputtering Microindentation Shear band Strain delocalization

Dynamical Behavior of SEIR-SVS Epidemic Models with Nonlinear Incidence and Vaccination

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Acta Mathematicae Applicatae Sinica 2022年第2期38卷 282-303页

作者： Xiao-mei feng Li-li LIU feng-qin ZHANG School of Mathematics and Informational Technology Yuncheng UniversityYuncheng 044000China School of Mathematics and Informational Sciences Shaanxi Normal UniversityXi'an 710062China Complex Systems Research Center Shanxi UniversityTaiyuan 030006China Shanxi Key Laboratory of Mathematical Techniques and Big Data Analysis on Disease Control and Prevention Shanxi UniversityTaiyuan 030006China

For some infectious diseases such as mumps,HBV,there is evidence showing that vaccinated individuals always lose their immunity at different rates depending on the inoculation time.In this paper,we propose an age-structured epidemic model using a step function to describe the rate at which vaccinated individuals lose immunity and reduce the age-structured epidemic model to the delay differential model.For the age-structured model,we consider the positivity,boundedness,and compactness of the semiflow and study global stability of equilibria by constructing appropriate Lyapunov functionals.Moreover,for the reduced delay differential equation model,we study the existence of the endemic equilibrium and prove the global stability of equilibria.Finally,some numerical simulations are provided to support our theoretical results and a brief discussion is given.

关键词： vaccination age-structured epidemic model delay differential equation model stability Lyapunov functional

Genetic and molecular exploration of maize environmental stress resilience:Toward sustainable agriculture

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Molecular Plant 2023年第10期16卷 1496-1517页

作者： Zhirui Yang Yibo Cao Yiting Shi Feng Qin Caifu Jiang Shuhua Yang State Key Laboratory of Plant Environmental Resilience Frontiers Science Center for Molecular Design BreedingCollege of Biological SciencesChina Agricultural UniversityBeijing 100193China

Global climate change exacerbates the effects of environmental stressors,such as drought,flooding,extreme temperatures,salinity,and alkalinity,on crop growth and grain yield,threatening the sustainability of the food supply.Maize(Zea mays)is one of the most widely cultivated crops and the most abundant grain crop in production worldwide.However,the stability of maize yield is highly dependent on environmental conditions.Recently,great progress has been made in understanding the molecular mechanisms underlying maize responses to environmental stresses and in developing stress-resilient varieties due to advances in high-throughput sequencing technologies,multi-omics analysis platforms,and automated phenotyping facilities.In this review,we summarize recent advances in dissecting the genetic factors and networks that contribute to maize abiotic stress tolerance through diverse strategies.We also discuss future challenges and opportunities for the development of climate-resilient maize varieties.

关键词： maize abiotic stress drought extreme temperatures salinity resistance

Does palynological diversity reflect floristic diversity?A case study from Northeast China

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中国科学:地球科学英文版 2023年第9期66卷 2097-2108页

作者： Yifan CUI Feng Qin Yan ZHAO Qiaoyu CUI Rongwei GENG Quan LI Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China University of Chinese Academy of Sciences Beijing 100049China Cluster of Excellence ROOTS Institute of Pre-and Protohistoric ArchaeologyKiel UniversityKiel 24118Germany

Fossil pollen data can provide important information of past vegetation diversity,on the basis of established relationship between modern palynological and floristic diversity.However,current studies on modern pollen assemblages in China have not examined this relationship yet.Herein,we report a case study from Northeast China,aiming to investigate the representation of modern palynological diversity to regional floristic diversity.A total of 87 sets of modern pollen and vegetation data from various vegetation types were applied to assess modern palynological diversity and floristic diversity in Northeast China,and the relationship between palynological and floristic diversity was studied using spatial pattern comparison and correlation analysis.Moreover,to reduce representation bias related to pollen production and dispersal,we calibrated pollen data using the Regional Estimates of Vegetation Abundance from Large Sites(REVEALS)model with Pollen Productivity Estimates(PPEs)and Fall Speeds of Pollen(FSP).The results show that the spatial variations of palynological and floristic richness among vegetation types are similar,and have a good positive correlation(r=0.41,p0.05).The calibration on pollen data using REVEALS model minimized the differences in spatial patterns between palynological and floristic diversity,and improved the correlations between them(richness,r=0.50,p<0.01;evenness,r=0.33,p<0.01).Our study indicates that palynological richness in Northeast China could reflect regional floristic richness in general,and the calibration with REVEALS model is recommended for reconstructing past floristic diversity from pollen data.

关键词： Northeast China Modern palynological diversity Floristic diversity Richness and evenness Community dissimilarity index REVEALS model

Analysis for Multiple Cracks in 2D Piezoelectric Bimaterial Using the Singular Integral Equation Method

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Acta Mechanica Solida Sinica 2022年第2期35卷 261-272页

作者： Ting Cao Xiaobin feng Taiyan qin College of Engineering China Agricultural UniversityBeijing 100083China Department of CAE BYD Auto Industry Co.LtdShenzhen 518118China College of Science China Agricultural UniversityBeijing 100083China

A singular integral equation method is proposed to analyze the two-dimensional(2D)multiple cracks in anisotropic piezoelectric bimaterial.Using the Somigliana formula,a set of singular integral equations for the multiple crack problems are derived,in which the unknown functions are the derivatives of the generalized displacement discontinuities of the crack surfaces.Then,the exact analytical solution of the extended singular stresses and extended stress intensity factors near the crack tip is obtained.Singular integrals of the singular integral equations are computed by the Gauss-Chebyshev collocation method.Finally,numerical solutions of the extended stress intensity factors of some examples are presented and discussed.

关键词： Piezoelectric bimaterial Boundary element method(BEM) Singular integral equation Stress intensity factor(SIF)