Nanomaterials have garnered recognition for their notable surface effects and demonstration of superior mechanical properties.Previous studies on the surface effects of nanomaterials,employing the finite element metho...Nanomaterials have garnered recognition for their notable surface effects and demonstration of superior mechanical properties.Previous studies on the surface effects of nanomaterials,employing the finite element method,often relied on simplified twodimensional models due to theoretical complexities.Consequently,these simplified models inadequately represent the mechanical properties of nanomaterials and fail to capture the substantial impact of surface effects,particularly the curvature dependence of nanosurfaces.This study applies the principle of minimum energy and leverages the Steigmann-Ogden surface theory of nanomaterials to formulate a novel finite element surface element that comprehensively accounts for surface effects.We conducted an analysis of the stress distribution and deformation characteristics of four typical 2D and 3D nanomaterial models.The accuracy of the developed surface element and finite element calculation method was verified through comparison with established references.The resulting finite element model provides a robust and compelling scientific approach for accurately predicting the mechanical performance of nanomaterials.展开更多
In this study,we performed a systematic analysis of the multiplicity dependence of hadron production at mid-rapidity(|y|<0.5),ranging from the light to the charm sector in proton-proton(pp)collisions at√s=13 TeV.T...In this study,we performed a systematic analysis of the multiplicity dependence of hadron production at mid-rapidity(|y|<0.5),ranging from the light to the charm sector in proton-proton(pp)collisions at√s=13 TeV.This study used a multi-phase transport(AMPT)model coupled with PYTHIA8 initial conditions.We investigated the baryon-to-meson and the strange-to-non-strange meson ratios varying with the charged particle density.By tuning the coalescence parameters,the AMPT model provides a reasonable description of the experimental data for the inclusive production of both light and charm hadrons,comparable to the string fragmentation model calculations with color reconnection effects.Additionally,we analyzed the relative production of hadrons by examining the self-normalized particle ratios as a function of the charged hadron density.Our findings suggest that parton evolution effects and the coalescence hadronization process in the AMPT model result in a strong flavor hierarchy in the multiplicity dependence of the baryon-to-meson ratio.Furthermore,our investigation of the p_(T) differential double ratio of the baryon-to-meson fraction between high-and low-multiplicity events revealed distinct modifications to the flavor associated baryon-to-meson ratio p_(T) shape in high-multiplicity events when comparing the coalescence hadronization model to the color reconnection model.These observations highlight the importance of understanding the hadronization process in high-energy pp collisions through comprehensive multiplicity-dependent multi-flavor analysis.展开更多
Partial phase transformation in NiTi-based refrigerants usually enables efficient and durable elastocaloric cooling,but its thermomechanical behavior with varying temperatures remains unclear.Keeping this in view,the ...Partial phase transformation in NiTi-based refrigerants usually enables efficient and durable elastocaloric cooling,but its thermomechanical behavior with varying temperatures remains unclear.Keeping this in view,the elastocaloric effect of NiTi under incomplete transformation across 15-100℃ is investigated and a superelastic deformation window between 25 and 85℃ is identified.Synchronous infrared thermography and digital image correlation,and an innovative macro-micro phase-field model are employed to examine martensitic transformation and elastocaloric properties of NiTi within the superelastic window.Experimental and simulated results consistently reveal that the spatiotemporal thermal profiles correlate with Lüders strain band evolution.As superelastic deformation temperature increases,strain localization intensifies,with Lüders bands favoring an inward strain growth over an outward expansion,resulting in a smaller yet more deformed martensitic transformation zone.The aggravated strain inhomogeneity makes the local endothermic undercooling tested at 85℃ up to about twice(−30.05℃)that at 25℃(−15.32℃),boosting the global cooling capacity by 65%,despite constant strain.The seeming contradiction between the larger elastocaloric effect and the narrower apparent martensitic transformation zone is elucidated by recourse to the simulations.It is found that the martensitic transformation within the Lüders bands is incomplete,proceeding in a macroscopically uniform but microscopically heterogeneous manner.Elevated temperatures within the superelastic window increase the transformed volume fraction and enhance martensitic transformation,thereby strengthening the global caloric effect.The work sheds light on the interplay between partial martensitic transformation and thermal behavior in NiTi under varying superelastic deformation temperatures,providing insights for advanced elastocaloric cooling applications.展开更多
OBJECTIVE:To observe the effect of different acupuncture frequencies on the abstinence rate which could be used as a reference for optimizing acupuncture cessation programs.METHODS:From July 2018 to June 2022,a total ...OBJECTIVE:To observe the effect of different acupuncture frequencies on the abstinence rate which could be used as a reference for optimizing acupuncture cessation programs.METHODS:From July 2018 to June 2022,a total of 220 smokers were recruited based on inclusion criteria and randomly divided into the high-frequency acupuncture group(HF group,n=110):5 times a week from the 1st to the 4th week,from weeks 5 to 8,three times a week and the low-frequency acupuncture group(LF group,n=110):3 times a week from the 1st to the 4th week,from weeks 5 to 8,twice a week,then treated for 8 weeks and followup at 1 month in Beijing.RESULTS:In total,162 subjects completed the whole study with a drop-out rate of 20.45%.The expiratory CO point abstinence rate was HF group 53/110(48.18%)vs LF group 41/110(37.27%)in Week 8(P=0.102)and HF group 46/110(41.82%)vs LF group 45/110(40.91%)in Week 12(P=0.891)and the HF acupuncture and LF acupuncture were nearly equal in the 8-week abstinence rate.In addition,both HF and LF acupuncture significantly reduced Fagerstr?m test for nicotine dependence scale(FTND)scores(P<0.05),Minnesota nicotine withdrawal scale(MNWS)scores(P<0.05),and Brief Questionnaire of Smoking Urges scale(QSU-Brief)scores(P<0.05),but HF acupuncture showed some superiority over LF acupuncture in relieving patients'smoking cravings(P<0.05).CONCLUSIONS:The study initially showed that both high-frequency acupuncture and low-frequency acupuncture treatment were safe and effective on smoking cessation for 8 weeks,but high-frequency acupuncture was advantageous in reducing smoking cravings.More accurate acupuncture frequency needs to be validated through larger clinical studies to optimize acupuncture smoking cessation programs.展开更多
Electrocatalysis has been investigated as a promising strategy to utilize green electricity to produce renewable fuels,valuable chemicals,and treat pollutants.Electrode kinetic analysis is a potent technique in interr...Electrocatalysis has been investigated as a promising strategy to utilize green electricity to produce renewable fuels,valuable chemicals,and treat pollutants.Electrode kinetic analysis is a potent technique in interrogating reaction mechanisms and evaluating the electrocatalysts.Electron transfer(ET)and proton‐coupled electron transfer(PCET)processes are widely present in reaction networks of electrocatalysis.pH dependence of the kinetics is frequently employed to evaluate whether an elementary step involves proton participation,which is determined by both the reversibility and the specific reactants of electrode reactions.In this article,we discuss the pH dependence of two widely used formulations of the Butler–Volmer kinetics for a model PCET step and highlight a potential pitfall in kinetic analysis.This work aims to provide guiding principles for distinguishing ET and PCET steps via kinetic measurements in electrolytes in a broad range pH values.展开更多
Objective:To evaluate the global liter-ature output on the relationship between brain-derived neurotrophic factor(BDNF)and cognitive function in al-cohol dependence syndrome using bibliometric methods and explore the ...Objective:To evaluate the global liter-ature output on the relationship between brain-derived neurotrophic factor(BDNF)and cognitive function in al-cohol dependence syndrome using bibliometric methods and explore the status and trends in this field.Method:The literature on the application of BDNF in cognitive impairment caused by alcohol dependence syndrome published from 1995 to 2023 were retrieved from Web of Science,and the relevant information(publication characteristics,country and institution,author,number of publications,citation,journal and research field,corresponding author,key words,etc.)was recorded.The bibliometrix R package was used for quantitative and qualitative analysis of publication output and author contributions.Result:A total of 99 articles were included.The overall number of publications in this field has increased over time.The countries and institutions that contributed the most to the field were the United States and the Academy of Medical Sciences of Iranian universities,respectively.Most of the authors were from the United States,followed by Spain,China,and Iran.Ceccanti M,Fiore M were the most productive authors.Publications with Ceccanti M had the highest h-index.The most cited reference author is Haenninen H(227 citations),and the number one published journal is Alcohol.Most articles were published in 2020(n=12)and 2022(n=11),followed by 2019 and 2021(n=10).The corresponding author has the largest number of publications from the United States,and more publications from a single country tend to have more cooperation from other countries.BDNF and alcohol appeared more frequently in various keyword clouds.However,significant differences remained in the author keyword cloud,keyword plus word cloud,and paper topic word cloud.Conclusion:BDNF has great potential in the application of cognitive dysfunction caused by alcohol dependence syndrome.Bibliometric methods and data visualization techniques can help understand the current state of research progress and enable relevant scholars and practitioners to predict the development trends in this field.展开更多
The thickness dependence of linearly polarized light-induced momentum anisotropy and the inverse spin Hall effect(PISHE)in topological insulator(TI)Bi_(2)Te_(3)films has been investigated.A significant enhancement of ...The thickness dependence of linearly polarized light-induced momentum anisotropy and the inverse spin Hall effect(PISHE)in topological insulator(TI)Bi_(2)Te_(3)films has been investigated.A significant enhancement of the PISHE signal is observed in the 12-quintuple-layer(QL)Bi_(2)Te_(3)film compared with that of the 3-and 5-QL samples,whereas a minimal value of photoinduced momentum anisotropy is found in the 12-QL sample.The photoinduced momentum anisotropy and the PISHE in Bi_(2)Te_(3)films are more than three and two orders of magnitude larger than those in Bi2Se3 films grown on SrTiO_(3)substrates,respectively.The 3-QL sample exhibits a sinusoidal dependence of the PISHE current on the light spot position,while the 5-QL and 12-QL samples show aW-shaped dependence,which arises from the different angles between the coordinate axis x and the in-plane crystallographic axis of the Bi_(2)Te_(3)films.Our findings demonstrate the critical role of film thickness in modulating both the photoinduced momentum anisotropy and the PISHE current,thereby suggesting a thickness-engineering strategy for designing novel optoelectronic devices based on TIs.展开更多
The post-fledging period, extending from fledging to independence, is a crucial life stage characterized by high mortality due to fledglings' limited mobility and inexperience. During this stage, fledglings gradua...The post-fledging period, extending from fledging to independence, is a crucial life stage characterized by high mortality due to fledglings' limited mobility and inexperience. During this stage, fledglings gradually increase their mobility, leave their parents, disperse from their natal site, and respond to the challenges of new environments. Characterizing these post-fledging movements and space use is essential for understanding juvenile survival strategies and devising targeted conservation measures. The Crested Ibis (Nipponia nippon), an endangered species and a highly protected animals at the national level in China, has seen limited research on its post-fledging movements and space use. From 2015 to 2023, we utilized biologgers, combined with field surveys, to study the movement and space use characteristics of 37 fledglings in Hanzhong City, Shaanxi Province, China, over a two-month post-fledging period. We quantified changes in activity levels (based on overall dynamic body acceleration), independence timing, onset of post-fledging dispersal, habitat selection, and daily activity rhythms after independence. Our results revealed individuals began independent living 26.23 ± 2.34 days post-fledging and onset of dispersal at 25.58 ± 2.33 days, with a range area at the natal of 2.08 ± 0.56 km^(2). The initial 30 days post-fledging are characterized as an ontogenetic phase marked by a rapid increase in body activity level. Fledglings preferred paddy fields during the independent period rather than the forests they relied on before independence. Interestingly, the daily activity rhythm, particularly foraging behavior, peaked at noon—contrasting with the expected morning and evening activity peaks—likely as an adaptation to avoid periods of peak human activity. Additionally, drowning, collisions, and predation in paddy fields are noteworthy causes of fledgling mortality. Consequently, we recommend protecting a 2-km^(2) area around the nest site for at least two-month post-fledging, implementing safety measures around power lines and cesspools. Additionally, reducing human disturbances near foraging habitats and expanding space within paddy fields would help mitigate survival pressures on fledglings.展开更多
Based on the EAM potential, a molecular dynamics study on the tensile properties of ultrathin nickel nanowires in the （100〉 orientation with diameters of 3.94, 4.95 and 5.99 nm was presented at different temperature...Based on the EAM potential, a molecular dynamics study on the tensile properties of ultrathin nickel nanowires in the （100〉 orientation with diameters of 3.94, 4.95 and 5.99 nm was presented at different temperatures and strain rates. The temperature and strain rate dependences of tensile properties were investigated. The simulation results show that the elastic modulus and the yield strength are gradually decreasing with the increase of temperature, while with the increase of the strain rate, the stress--strain curves fluctuate more intensely and the ultrathin nickel nanowires rupture at one smaller and smaller strain. At an ideal temperature of 0.01 K, the yield strength of the nanowires drops rapidly with the increase of strain rate, and at other temperatures the strain rate has a little influence on the elastic modulus and the yield strength. Finally, the effects of size on the tensile properties of ultrathin nickel nanowires were briefly discussed.展开更多
Crystal patterns in ultrathin films of six poly（ethylene oxide） fractions with molecular weights from 25000 to 932000 g/mol were characterized within crystallization temperature range from 20 ℃to 60℃. Labyrinthine...Crystal patterns in ultrathin films of six poly（ethylene oxide） fractions with molecular weights from 25000 to 932000 g/mol were characterized within crystallization temperature range from 20 ℃to 60℃. Labyrinthine, dendritic and faceted crystal patterns were observed in different temperature ranges, and then labyrinthine-to-dendritic and dendritic-to- faceted transition temperatures T_L-D and T_D-F were quantitatively identified. Their molecular weight dependences are T_L-D（M_w） = T_L-D（∞） -K_L-D/M_w, where T_L-D（∞） = 38.2 ℃ and K_L-D = 253000 ℃.g/mol and T_D-F（M_w） = T_D-F（∞） -K_D-F/M_w, where T_D-F（∞） = 54.7 ℃ and K_D-F= 27000 ℃.g/mol. Quasi two-dimensional blob models were proposed to provide empirical explanations of the molecular weight dependences. The labyrinthine-to-dendritic transition is attributed to a molecular diffusion process change from a local-diffusion to diffusion-limited-aggregation （DLA） and a polymer chain with M_w ≈253000 g/mol within a blob can join crystals independently. The dendritic-to-faceted transition is attributed to a turnover of the pattern formation mechanism from DLA to crystallization control, and a polymer chain with a M_w ≈27000 g/tool as an independent blob crosses to a depletion zone to join crystals. These molecular weight dependences reveal a macromolecular effect on the crystal pattern formation and selection of crystalline polymers.展开更多
We study the influences of the temperature on the energy-band structure for the Holstein molecular-crystal model. We show that the energy-band width and the energy-gap width of a solid are relevant to both the interac...We study the influences of the temperature on the energy-band structure for the Holstein molecular-crystal model. We show that the energy-band width and the energy-gap width of a solid are relevant to both the interaction between an electron and thermal phonons and to thermal expansion. For a one-dimensional Li atom lattice chain, under the chosen parameters,the width of the ls and 2s energy bands narrows as the temperature increases and the energy-gap width between the two bands widens. These results agree qualitatively with those observed experimentally. Studying temperature dependence of the energy-band structure is of great importance for understanding optical and transporting characteristics of a solid.展开更多
基金supported by the Jiangsu Funding Program for Excellent Postdoctoral Talent (Grant No.2023ZB397)the Project funded by China Postdoctoral Science Foundation (Grant No.2023M732986).
文摘Nanomaterials have garnered recognition for their notable surface effects and demonstration of superior mechanical properties.Previous studies on the surface effects of nanomaterials,employing the finite element method,often relied on simplified twodimensional models due to theoretical complexities.Consequently,these simplified models inadequately represent the mechanical properties of nanomaterials and fail to capture the substantial impact of surface effects,particularly the curvature dependence of nanosurfaces.This study applies the principle of minimum energy and leverages the Steigmann-Ogden surface theory of nanomaterials to formulate a novel finite element surface element that comprehensively accounts for surface effects.We conducted an analysis of the stress distribution and deformation characteristics of four typical 2D and 3D nanomaterial models.The accuracy of the developed surface element and finite element calculation method was verified through comparison with established references.The resulting finite element model provides a robust and compelling scientific approach for accurately predicting the mechanical performance of nanomaterials.
基金supported by the National Natural Science Foundation of China(Nos.12205259 and 12147101)the Fundamental Research Funds for the Central Universities,China University of Geosciences(Wuhan)with No.G1323523064.
文摘In this study,we performed a systematic analysis of the multiplicity dependence of hadron production at mid-rapidity(|y|<0.5),ranging from the light to the charm sector in proton-proton(pp)collisions at√s=13 TeV.This study used a multi-phase transport(AMPT)model coupled with PYTHIA8 initial conditions.We investigated the baryon-to-meson and the strange-to-non-strange meson ratios varying with the charged particle density.By tuning the coalescence parameters,the AMPT model provides a reasonable description of the experimental data for the inclusive production of both light and charm hadrons,comparable to the string fragmentation model calculations with color reconnection effects.Additionally,we analyzed the relative production of hadrons by examining the self-normalized particle ratios as a function of the charged hadron density.Our findings suggest that parton evolution effects and the coalescence hadronization process in the AMPT model result in a strong flavor hierarchy in the multiplicity dependence of the baryon-to-meson ratio.Furthermore,our investigation of the p_(T) differential double ratio of the baryon-to-meson fraction between high-and low-multiplicity events revealed distinct modifications to the flavor associated baryon-to-meson ratio p_(T) shape in high-multiplicity events when comparing the coalescence hadronization model to the color reconnection model.These observations highlight the importance of understanding the hadronization process in high-energy pp collisions through comprehensive multiplicity-dependent multi-flavor analysis.
基金financially supported by the National Key Re-search and Development Program of China(No.2017YFB0701801)。
文摘Partial phase transformation in NiTi-based refrigerants usually enables efficient and durable elastocaloric cooling,but its thermomechanical behavior with varying temperatures remains unclear.Keeping this in view,the elastocaloric effect of NiTi under incomplete transformation across 15-100℃ is investigated and a superelastic deformation window between 25 and 85℃ is identified.Synchronous infrared thermography and digital image correlation,and an innovative macro-micro phase-field model are employed to examine martensitic transformation and elastocaloric properties of NiTi within the superelastic window.Experimental and simulated results consistently reveal that the spatiotemporal thermal profiles correlate with Lüders strain band evolution.As superelastic deformation temperature increases,strain localization intensifies,with Lüders bands favoring an inward strain growth over an outward expansion,resulting in a smaller yet more deformed martensitic transformation zone.The aggravated strain inhomogeneity makes the local endothermic undercooling tested at 85℃ up to about twice(−30.05℃)that at 25℃(−15.32℃),boosting the global cooling capacity by 65%,despite constant strain.The seeming contradiction between the larger elastocaloric effect and the narrower apparent martensitic transformation zone is elucidated by recourse to the simulations.It is found that the martensitic transformation within the Lüders bands is incomplete,proceeding in a macroscopically uniform but microscopically heterogeneous manner.Elevated temperatures within the superelastic window increase the transformed volume fraction and enhance martensitic transformation,thereby strengthening the global caloric effect.The work sheds light on the interplay between partial martensitic transformation and thermal behavior in NiTi under varying superelastic deformation temperatures,providing insights for advanced elastocaloric cooling applications.
基金the Fund of Science and Technology Innovation Project of Chinese Academy of Chinese Medical Sciences Project:Self-service Acupuncture Smoking Cessation Research and Development(No.CI2021A03506)Fund of Capital Health Development Special Research Project:Research on Development and Clinical Applicalion of Wrist Acupuncture Smoking Cessation Instrument(No.2022-1-4281)。
文摘OBJECTIVE:To observe the effect of different acupuncture frequencies on the abstinence rate which could be used as a reference for optimizing acupuncture cessation programs.METHODS:From July 2018 to June 2022,a total of 220 smokers were recruited based on inclusion criteria and randomly divided into the high-frequency acupuncture group(HF group,n=110):5 times a week from the 1st to the 4th week,from weeks 5 to 8,three times a week and the low-frequency acupuncture group(LF group,n=110):3 times a week from the 1st to the 4th week,from weeks 5 to 8,twice a week,then treated for 8 weeks and followup at 1 month in Beijing.RESULTS:In total,162 subjects completed the whole study with a drop-out rate of 20.45%.The expiratory CO point abstinence rate was HF group 53/110(48.18%)vs LF group 41/110(37.27%)in Week 8(P=0.102)and HF group 46/110(41.82%)vs LF group 45/110(40.91%)in Week 12(P=0.891)and the HF acupuncture and LF acupuncture were nearly equal in the 8-week abstinence rate.In addition,both HF and LF acupuncture significantly reduced Fagerstr?m test for nicotine dependence scale(FTND)scores(P<0.05),Minnesota nicotine withdrawal scale(MNWS)scores(P<0.05),and Brief Questionnaire of Smoking Urges scale(QSU-Brief)scores(P<0.05),but HF acupuncture showed some superiority over LF acupuncture in relieving patients'smoking cravings(P<0.05).CONCLUSIONS:The study initially showed that both high-frequency acupuncture and low-frequency acupuncture treatment were safe and effective on smoking cessation for 8 weeks,but high-frequency acupuncture was advantageous in reducing smoking cravings.More accurate acupuncture frequency needs to be validated through larger clinical studies to optimize acupuncture smoking cessation programs.
基金supported by the Beijing Natural Science Foundation Key Research Program(Grant Z240026)the Beijing National Laboratory for Molecular Sciences.
文摘Electrocatalysis has been investigated as a promising strategy to utilize green electricity to produce renewable fuels,valuable chemicals,and treat pollutants.Electrode kinetic analysis is a potent technique in interrogating reaction mechanisms and evaluating the electrocatalysts.Electron transfer(ET)and proton‐coupled electron transfer(PCET)processes are widely present in reaction networks of electrocatalysis.pH dependence of the kinetics is frequently employed to evaluate whether an elementary step involves proton participation,which is determined by both the reversibility and the specific reactants of electrode reactions.In this article,we discuss the pH dependence of two widely used formulations of the Butler–Volmer kinetics for a model PCET step and highlight a potential pitfall in kinetic analysis.This work aims to provide guiding principles for distinguishing ET and PCET steps via kinetic measurements in electrolytes in a broad range pH values.
基金supported by grants from the Scientific Research Fund project of Education Department of Yunnan Province(2024J0314)Joint Special Project on Basic Research of Yunnan Provincial Department of Science and Technology and Kunming Medical University(202501AY070001-206).
文摘Objective:To evaluate the global liter-ature output on the relationship between brain-derived neurotrophic factor(BDNF)and cognitive function in al-cohol dependence syndrome using bibliometric methods and explore the status and trends in this field.Method:The literature on the application of BDNF in cognitive impairment caused by alcohol dependence syndrome published from 1995 to 2023 were retrieved from Web of Science,and the relevant information(publication characteristics,country and institution,author,number of publications,citation,journal and research field,corresponding author,key words,etc.)was recorded.The bibliometrix R package was used for quantitative and qualitative analysis of publication output and author contributions.Result:A total of 99 articles were included.The overall number of publications in this field has increased over time.The countries and institutions that contributed the most to the field were the United States and the Academy of Medical Sciences of Iranian universities,respectively.Most of the authors were from the United States,followed by Spain,China,and Iran.Ceccanti M,Fiore M were the most productive authors.Publications with Ceccanti M had the highest h-index.The most cited reference author is Haenninen H(227 citations),and the number one published journal is Alcohol.Most articles were published in 2020(n=12)and 2022(n=11),followed by 2019 and 2021(n=10).The corresponding author has the largest number of publications from the United States,and more publications from a single country tend to have more cooperation from other countries.BDNF and alcohol appeared more frequently in various keyword clouds.However,significant differences remained in the author keyword cloud,keyword plus word cloud,and paper topic word cloud.Conclusion:BDNF has great potential in the application of cognitive dysfunction caused by alcohol dependence syndrome.Bibliometric methods and data visualization techniques can help understand the current state of research progress and enable relevant scholars and practitioners to predict the development trends in this field.
基金supported by the National Natural Science Foundation of China(Grant Nos.62074036,61674038,and 11574302)the Foreign Cooperation Project of Fujian Province,China(Grant No.2023I0005)+2 种基金the Open Research Fund Program of the State Key Laboratory of Low Dimensional Quantum Physics(Grant No.KF202108)the National Key Research and Development Program of China(Grant No.2016YFB0402303)the Foundation of the Fujian Provincial Department of Industry and Information Technology of China(Grant No.82318075).
文摘The thickness dependence of linearly polarized light-induced momentum anisotropy and the inverse spin Hall effect(PISHE)in topological insulator(TI)Bi_(2)Te_(3)films has been investigated.A significant enhancement of the PISHE signal is observed in the 12-quintuple-layer(QL)Bi_(2)Te_(3)film compared with that of the 3-and 5-QL samples,whereas a minimal value of photoinduced momentum anisotropy is found in the 12-QL sample.The photoinduced momentum anisotropy and the PISHE in Bi_(2)Te_(3)films are more than three and two orders of magnitude larger than those in Bi2Se3 films grown on SrTiO_(3)substrates,respectively.The 3-QL sample exhibits a sinusoidal dependence of the PISHE current on the light spot position,while the 5-QL and 12-QL samples show aW-shaped dependence,which arises from the different angles between the coordinate axis x and the in-plane crystallographic axis of the Bi_(2)Te_(3)films.Our findings demonstrate the critical role of film thickness in modulating both the photoinduced momentum anisotropy and the PISHE current,thereby suggesting a thickness-engineering strategy for designing novel optoelectronic devices based on TIs.
基金funded by the National Natural Science Foundation of China(No.32270554,32400400).
文摘The post-fledging period, extending from fledging to independence, is a crucial life stage characterized by high mortality due to fledglings' limited mobility and inexperience. During this stage, fledglings gradually increase their mobility, leave their parents, disperse from their natal site, and respond to the challenges of new environments. Characterizing these post-fledging movements and space use is essential for understanding juvenile survival strategies and devising targeted conservation measures. The Crested Ibis (Nipponia nippon), an endangered species and a highly protected animals at the national level in China, has seen limited research on its post-fledging movements and space use. From 2015 to 2023, we utilized biologgers, combined with field surveys, to study the movement and space use characteristics of 37 fledglings in Hanzhong City, Shaanxi Province, China, over a two-month post-fledging period. We quantified changes in activity levels (based on overall dynamic body acceleration), independence timing, onset of post-fledging dispersal, habitat selection, and daily activity rhythms after independence. Our results revealed individuals began independent living 26.23 ± 2.34 days post-fledging and onset of dispersal at 25.58 ± 2.33 days, with a range area at the natal of 2.08 ± 0.56 km^(2). The initial 30 days post-fledging are characterized as an ontogenetic phase marked by a rapid increase in body activity level. Fledglings preferred paddy fields during the independent period rather than the forests they relied on before independence. Interestingly, the daily activity rhythm, particularly foraging behavior, peaked at noon—contrasting with the expected morning and evening activity peaks—likely as an adaptation to avoid periods of peak human activity. Additionally, drowning, collisions, and predation in paddy fields are noteworthy causes of fledgling mortality. Consequently, we recommend protecting a 2-km^(2) area around the nest site for at least two-month post-fledging, implementing safety measures around power lines and cesspools. Additionally, reducing human disturbances near foraging habitats and expanding space within paddy fields would help mitigate survival pressures on fledglings.
基金Project(51205302)supported by the National Natural Science Foundation of ChinaProject(2013JM7017)supported by the Natural Science Basic Research Plan in Shanxi Province of ChinaProject(K5051304006)supported by the Fundamental Research Funds for the Central Universities,China
文摘Based on the EAM potential, a molecular dynamics study on the tensile properties of ultrathin nickel nanowires in the （100〉 orientation with diameters of 3.94, 4.95 and 5.99 nm was presented at different temperatures and strain rates. The temperature and strain rate dependences of tensile properties were investigated. The simulation results show that the elastic modulus and the yield strength are gradually decreasing with the increase of temperature, while with the increase of the strain rate, the stress--strain curves fluctuate more intensely and the ultrathin nickel nanowires rupture at one smaller and smaller strain. At an ideal temperature of 0.01 K, the yield strength of the nanowires drops rapidly with the increase of strain rate, and at other temperatures the strain rate has a little influence on the elastic modulus and the yield strength. Finally, the effects of size on the tensile properties of ultrathin nickel nanowires were briefly discussed.
基金financially supported by the National Science Foundation of China(No.20874053)
文摘Crystal patterns in ultrathin films of six poly（ethylene oxide） fractions with molecular weights from 25000 to 932000 g/mol were characterized within crystallization temperature range from 20 ℃to 60℃. Labyrinthine, dendritic and faceted crystal patterns were observed in different temperature ranges, and then labyrinthine-to-dendritic and dendritic-to- faceted transition temperatures T_L-D and T_D-F were quantitatively identified. Their molecular weight dependences are T_L-D（M_w） = T_L-D（∞） -K_L-D/M_w, where T_L-D（∞） = 38.2 ℃ and K_L-D = 253000 ℃.g/mol and T_D-F（M_w） = T_D-F（∞） -K_D-F/M_w, where T_D-F（∞） = 54.7 ℃ and K_D-F= 27000 ℃.g/mol. Quasi two-dimensional blob models were proposed to provide empirical explanations of the molecular weight dependences. The labyrinthine-to-dendritic transition is attributed to a molecular diffusion process change from a local-diffusion to diffusion-limited-aggregation （DLA） and a polymer chain with M_w ≈253000 g/mol within a blob can join crystals independently. The dendritic-to-faceted transition is attributed to a turnover of the pattern formation mechanism from DLA to crystallization control, and a polymer chain with a M_w ≈27000 g/tool as an independent blob crosses to a depletion zone to join crystals. These molecular weight dependences reveal a macromolecular effect on the crystal pattern formation and selection of crystalline polymers.
文摘We study the influences of the temperature on the energy-band structure for the Holstein molecular-crystal model. We show that the energy-band width and the energy-gap width of a solid are relevant to both the interaction between an electron and thermal phonons and to thermal expansion. For a one-dimensional Li atom lattice chain, under the chosen parameters,the width of the ls and 2s energy bands narrows as the temperature increases and the energy-gap width between the two bands widens. These results agree qualitatively with those observed experimentally. Studying temperature dependence of the energy-band structure is of great importance for understanding optical and transporting characteristics of a solid.
