Dispersals,colonisation,immigration and population assimilation or replacement are fundamental themes in the Palaeolithic record of East Asia.Some of these issues can be studied within a biogeographic framework that e...Dispersals,colonisation,immigration and population assimilation or replacement are fundamental themes in the Palaeolithic record of East Asia.Some of these issues can be studied within a biogeographic framework that explains why and how the distribution of hominin species changed over time and space in response to climatic and environmental change.Because hominins(and especially humans)can change their behaviour through technical,social and cognitive developments,biogeographic models also have to incorporate this factor when investigating dispersals.This is particularly important with the dispersals in East Asia by Homo sapiens into rainforests,across open sea to off-shore islands,to the Arctic and the highest parts of the Tibetan Plateau.This paper suggests how hominin and human dispersals in East Asia might be investigated by using a biogeographic framework that can incorporate changes in hominin adaptability and behaviour.展开更多
This letter addresses challenges in the clinical translation of BIBR1532,a promising telomerase inhibitor,for the treatment of esophageal squamous cell carcinoma(ESCC).BIBR1532 exerts its anti-cancer effect by activat...This letter addresses challenges in the clinical translation of BIBR1532,a promising telomerase inhibitor,for the treatment of esophageal squamous cell carcinoma(ESCC).BIBR1532 exerts its anti-cancer effect by activating DNA damage response(ATR/CHK1 and ATM/CHK2)pathways and downregulating telomere-binding proteins.Although its therapeutic potential is limited by poor aqueous solubility,solid dispersion(SD)technology may overcome this obstacle.Systematic analysis using PubChem-derived simplified molecular input line entry system identifiers and artificial intelligence-driven FormulationDT platform evaluation(oral formulation feasibility index:0.38)revealed that the SD technology,with superior scalability(32 approved products by 2021)and lower production risks,outperforms lipid-based formulations as an optimal dissolution strategy.Material analysis revealed hydroxypropyl methylcellulose(HPMC)as the optimal carrier with lower hygroscopicity,higher temperature and no intestinal targeting,thus enabling ESCC therapy.HPMC-based SD enhances BIBR1532 solubility and bioavailability for effective ESCC treatment.Future studies should focus on pilot tests for SD fabrication.展开更多
Oxide dispersion strengthened(ODS)alloys are extensively used owing to high thermostability and creep strength contributed from uniformly dispersed fine oxides particles.However,the existence of these strengthening pa...Oxide dispersion strengthened(ODS)alloys are extensively used owing to high thermostability and creep strength contributed from uniformly dispersed fine oxides particles.However,the existence of these strengthening particles also deteriorates the processability and it is of great importance to establish accurate processing maps to guide the thermomechanical processes to enhance the formability.In this study,we performed particle swarm optimization-based back propagation artificial neural network model to predict the high temperature flow behavior of 0.25wt%Al2O3 particle-reinforced Cu alloys,and compared the accuracy with that of derived by Arrhenius-type constitutive model and back propagation artificial neural network model.To train these models,we obtained the raw data by fabricating ODS Cu alloys using the internal oxidation and reduction method,and conducting systematic hot compression tests between 400 and800℃with strain rates of 10^(-2)-10 S^(-1).At last,processing maps for ODS Cu alloys were proposed by combining processing parameters,mechanical behavior,microstructure characterization,and the modeling results achieved a coefficient of determination higher than>99%.展开更多
This paper studies an epidemic model with nonlocal dispersals.We focus on the influences of initial data and nonlocal dispersals on its spatial propagation.Here,initial data stand for the spatial concentrations of the...This paper studies an epidemic model with nonlocal dispersals.We focus on the influences of initial data and nonlocal dispersals on its spatial propagation.Here,initial data stand for the spatial concentrations of the infectious agent and the infectious human population when the epidemic breaks out and the nonlocal dispersals mean their diffusion strategies.Two types of initial data decaying to zero exponentially or faster are considered.For the first type,we show that spreading speeds are two constants whose signs change with the number of elements in some set.Moreover,we find an interesting phenomenon:the asymmetry of nonlocal dispersals can influence the propagating directions of the solutions and the stability of steady states.For the second type,we show that the spreading speed is decreasing with respect to the exponentially decaying rate of initial data,and further,its minimum value coincides with the spreading speed for the first type.In addition,we give some results about the nonexistence of traveling wave solutions and the monotone property of the solutions.Finally,some applications are presented to illustrate the theoretical results.展开更多
Mammals have high dispersal ability,and many lineages can spread across the continents when a landbridge appears.Here,we summarize the dispersal of mammals between the Old and New World at the end of the Miocene.Our a...Mammals have high dispersal ability,and many lineages can spread across the continents when a landbridge appears.Here,we summarize the dispersal of mammals between the Old and New World at the end of the Miocene.Our analysis suggested that the three phases of dispersal represented the largest dispersal tide during the Neogene,and the direction of dispersal is dominated by being from the Old to New World.Judging from the components that crossed the dispersal corridor,the Arctic environment near the Beringia corridor in the first phase(~7.5 Ma)is a mixed environment,and in the second phase(~6.5 Ma)is an open environment,and in the third phase(~5.8 Ma and continue to the Pliocene)is a wooded(closed)environment.A clear trend of eastern Asian humidification driven by Asian monsoon and the global C4 grassland expansion explain this dispersal pattern.The boost of mammalian dispersals is controlled by the heterogeneity of environmental changes in different continents.展开更多
River embankments are designed to defend against floods over coastal and riparian areas.It is important to early detect unexpected damages on embankments before they exacerbate.To continuously monitor the stability of...River embankments are designed to defend against floods over coastal and riparian areas.It is important to early detect unexpected damages on embankments before they exacerbate.To continuously monitor the stability of the embankments and efficiently recognize such potential damages,this study takes SAR(Synthetic Aperture Radar)derived deformation as an indicator of the embankment instability,and customizes a multi-temporal InSAR(Interferometric SAR)approach-small baseline subset.Specifically,during InSAR processing,we apply a two-step amplitude difference dispersion threshold method to extract InSAR measurement points,thus improving the point density within the embankment.We applied this method to the Kangshan Embankment(KE)using 147 Sentinel-1 acquired between 2017 and 2021.We categorized KE into Waterside Slope(WS),Embankment Top(ET),and Landside Slope(LS)using InSAR height estimation.Given the dominance of downslope movement,we developed a projection matrix from InSAR-derived deformation in the satellite line-of-sight direction onto WS and LS.The study shows that KE was generally stable during the five-year period,while WS,ET,and LS experienced different deformation processes.For instance,seasonal variation was observed from the deformation time series,especially between every April and November.We applied the principal component analysis to the time-series displacement and analyzed the results in conjunction with the rainfall data of Kangshan Township.It showed that deformation due to rainfall equals 80.93%,81.30%,and 82.46%of the total deformation for WS,ET,and LS,respectively,indicating that rainfall is one of the environmental driving factors affecting the deformations.We conclude that the proposed methodology is suited for systematic embankment monitoring and identifies major driving forces.展开更多
CO_(2)-responsive gels,which swell upon contact with CO_(2),are widely used for profile control to plug high-permeability gas flow channels in carbon capture,utilization,and storage(CCUS)applications in oil reser-voir...CO_(2)-responsive gels,which swell upon contact with CO_(2),are widely used for profile control to plug high-permeability gas flow channels in carbon capture,utilization,and storage(CCUS)applications in oil reser-voirs.However,the use of these gels in high-temperature CCUS applications is limited due to their rever-sible swelling behavior at elevated temperatures.In this study,a novel dispersed particle gel(DPG)suspension is developed for high-temperature profile control in CCUS applications.First,we synthesize a double-network hydrogel consisting of a crosslinked polyacrylamide(PAAm)network and a crosslinked sodium alginate(SA)network.The hydrogel is then sheared in water to form a pre-prepared DPG suspen-sion.To enhance its performance,the gel particles are modified by introducing potassium methylsilan-etriolate(PMS)upon CO_(2) exposure.Comparing the particle size distributions of the modified and pre-prepared DPG suspension reveals a significant swelling of gel particles,over twice their original size.Moreover,subjecting the new DPG suspension to a 100℃ environment for 24 h demonstrates that its gel particle sizes do not decrease,confirming irreversible swelling,which is a significant advantage over the traditional CO_(2)-responsive gels.Thermogravimetric analysis further indicates improved thermal sta-bility compared to the pre-prepared DPG particles.Core flooding experiments show that the new DPG suspension achieves a high plugging efficiency of 95.3%in plugging an ultra-high permeability sandpack,whereas the pre-prepared DPG suspension achieves only 82.8%.With its high swelling ratio,irreversible swelling at high temperatures,enhanced thermal stability,and superior plugging performance,the newly developed DPG suspension in this work presents a highly promising solution for profile control in high-temperature CCUS applications.展开更多
In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not ...In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.展开更多
Theoretical analysis has demonstrated that the dispersion relation of chorus waves plays an essential role in the resonant interaction and energy transformation between the waves and magnetospheric electrons.Previous ...Theoretical analysis has demonstrated that the dispersion relation of chorus waves plays an essential role in the resonant interaction and energy transformation between the waves and magnetospheric electrons.Previous quantitative analyses often simplified the chorus dispersion relation by using the cold plasma assumption.However,the applicability of the cold plasma assumption is doubtful,especially during geomagnetic disturbances.We here present a systematic statistical analysis on the validity of the cold plasma dispersion relation of chorus waves based on observations from the Van Allen Probes over the period from 2012 to 2018.The statistical results show that the observed magnetic field intensities deviate substantially from those calculated from the cold plasma dispersion relation and that they become more pronounced with an increase in geomagnetic activity or a decrease in background plasma density.The region with large deviations is mainly concentrated in the nightside and expands in both the radial and azimuthal directions as the geomagnetic activity increases or the background plasma density decreases.In addition,the bounce-averaged electron scattering rates are computed by using the observed and cold plasma dispersion relation of chorus waves.Compared with usage of the cold plasma dispersion relation,usage of the observed dispersion relation considerably lowers the minimum resonant energy of electrons and lowers the scattering rates of electrons above tens of kiloelectronvolts but enhances those below.Furthermore,these differences are more pronounced with the enhancement of geomagnetic activity or the decrease in background plasma density.展开更多
93W-4.9Ni-2.1Fe alloys strengthened by nanoscale ZrC particles were prepared by spark-plasma-sintering(SPS)and hot rotary swaging,separately.Results show that the addition of a small number of ZrC nanoparticles can re...93W-4.9Ni-2.1Fe alloys strengthened by nanoscale ZrC particles were prepared by spark-plasma-sintering(SPS)and hot rotary swaging,separately.Results show that the addition of a small number of ZrC nanoparticles can refine grains and increase the hardness of the WNiFe alloys,but hinder the formation of theγ-(Ni,Fe)phase during SPS.SPSed WNiFe and WNiFe-ZrC alloys are brittle at room temperature,while the swaged WNiFe and WNiFe-0.5ZrC(wt%)alloys are ductile.At 400°C,the swaged WNiFe-0.5ZrC alloy exhibits both higher tensile strength and better ductility than the swaged WNiFe.The nanoscale particles distributed in the W grains andγ-(Ni,Fe)phase provide a good pinning effect,which enhances the strength.The thermal conductivity of swaged WNiFe-0.5ZrC is only 71 W·m^(-1)·K^(-1)at room temperature,but it increases to about 100 W·m^(-1)·K^(-1)at 800°C,which is close to that of pure W(121 W·m^(-1)·K^(-1)).These results show the potential of WNiFe alloys as plasma-facing materials in fusion reactor.展开更多
Fine nickel powders with a narrow particle size distribution were prepared by reducing nickel hydroxide in aqueous solution.The formation and reduction pathways of nickel powder were analyzed,as well as the effects of...Fine nickel powders with a narrow particle size distribution were prepared by reducing nickel hydroxide in aqueous solution.The formation and reduction pathways of nickel powder were analyzed,as well as the effects of the molar ratio of hydrazine hydrate to nickel hydroxide,hydrazine concentration,and the dosage of surfactant PEG6000 on particle size,surface morphology,and dispersion.Results reveal that the nickel particle nucleation occurs on the nickel hydroxide surface,and the nickel hydroxide gradually dissolves during the reaction.With the increase in molar ratio of hydrazine hydrate to nickel hydroxide,the nickel particle size is initially decreased and then increased.Higher hydrazine hydrate concentrations result in smaller particle sizes.A small amount of PEG6000 surfactant can improve dispersion of nickel particles,but a higher amount of PEG6000 surfactant results in the maintenance of the morphology of nickel hydroxide.Adjusting the surfactant dosage can control the average particle size between 1-2μm.展开更多
Graphene and its derivatives are two-dimensional nanomaterials with exceptional physical and chemical properties.Research has shown that their addition can counter the inherent deficiencies of cementbased composites,i...Graphene and its derivatives are two-dimensional nanomaterials with exceptional physical and chemical properties.Research has shown that their addition can counter the inherent deficiencies of cementbased composites,including low tensile strength,poor toughness,and high susceptibility to cracking.However,because of its high specific surface area and the van der Waals force between layers,graphene is prone to agglomerate in the cement matrix which can make the properties worse.Hence,improving the graphene dispersion is essential.The surface structure and properties of graphene and its derivatives are first introduced,and the different methods for their dispersion in cement-based materials are reviewed.Their effects on the mechanical properties and durability of cement-based materials are then summarized.Based on these results,the microscopic and nanoscopic mechanisms of the way graphene and its derivatives affect cement-based materials are elaborated.Current problems and future trends in this research area are then considered.展开更多
For segmented detectors,surface flatness is critical as it directly influences both energy resolution and image clarity.Additionally,the limited adjustment range of the segmented detectors necessitates precise benchma...For segmented detectors,surface flatness is critical as it directly influences both energy resolution and image clarity.Additionally,the limited adjustment range of the segmented detectors necessitates precise benchmark construction.This paper proposes an architecture for detecting detector flatness based on channel spectral dispersion.By measuring the dispersion fringes for coplanar adjustment,the final adjustment residual is improved to better than 300 nm.This result validates the feasibility of the proposed technology and provides significant technical support for the development of next-generation large-aperture sky survey equipment.展开更多
Catalytic oxidation desulfurization(CODS)technology has shown great promise for diesel desulfurization by virtue of its low cost,mild reaction conditions,and superior desulfurization performance.Herein,a series of FeM...Catalytic oxidation desulfurization(CODS)technology has shown great promise for diesel desulfurization by virtue of its low cost,mild reaction conditions,and superior desulfurization performance.Herein,a series of FeMoO_(x)/LaTiO_(y)-z samples with diverse Fe/Mo ratios were prepared via a facile citric acid-assisted method.The impact of Fe incorporation on the dispersion and surface elemental states of Mo species,as well as oxygen species content of the synthesized FeMoO_(x)/LaTiO_(y)-z catalysts were systematically characterized using TEM,BET,UV-vis DRS,XPS,XANES,and reaction kinetics,and their CODS performances were examined for 4,6-DMDBT removal.Experimental results demonstrated that Fe/Mo ratio significantly affected the Ti−O bond strength,surface dispersion and electronic structure of Mo O_(2)species on FeMoO_(x)/LaTiO_(y)-z catalysts.FeMoO_(x)/LaTiO_(y)-2 catalyst showed outstanding cycling durability and the best CODS performance with almost 100%removal of 4,6-DMDBT from model oil within 75 min due to its proper MoO3 dispersion,optimal redox property,and the most oxygen vacancy concentration.Nevertheless,further enhancing Fe content led to the increased dispersion of Mo species,while the decrease active Mo species as well as the increase of steric effect for 4,6-DMDBT accessing to the catalytic reactive sites considerably increase the apparent activation energy of FeMoO_(x)/LaTiO_(y)-z(z>2)catalysts during the CODS process,thereby seriously suppressing their CODS performances.Moreover,Radical trapping experiments reveal that the·,generated by the activation of O_(2)at the active sites,catalytic oxidized 4,6-DMDBT to the product of 4,6-DMDBTO_(2),thereby enabling both deep desulfurization and recovery of high-value 4,6-DMDBTO_(2).These findings offer an alternative strategy to achieve ultra deep desulfurization as well as separate and recover high economic value sulfone substances from diesel.展开更多
Dispersal is an important life history trait with signifcant consequences for spatially structured populations,as the exchange of individuals between habitat patches is crucial for maintaining metapopulation connectiv...Dispersal is an important life history trait with signifcant consequences for spatially structured populations,as the exchange of individuals between habitat patches is crucial for maintaining metapopulation connectivity.In this study,we used a long-term data set(2005–2023)to describe dispersal patterns in a patchy population of the Western Yellow Wagtail Motacilla fava within a large(approximately 1,300 km2)study area in the boreal zone of European Russia.We quantifed dispersal distances for birds that dispersed outside their natal or breeding habitat patches and applied a multistate capture–recapture approach to estimate natal and breeding dispersal probabilities.Of 395 adult wagtails and 1,610 nestlings ringed,3%of birds ringed as adults and 3%of birds ringed as nestlings were resighted outside their natal or breeding patches.The probability of natal dispersal(0.29±0.05)was signifcantly higher than the probability of breeding dispersal(0.05±0.01).The median natal dispersal distances(2.8 km for males,3.9 km for females)were the same as the median breeding dispersal distances(2.7 km for males,3.9 km for females).We did not fnd a signifcant effect of the fedging date on either the natal dispersal distance or the natal dispersal probability.Similarly,we did not fnd a signifcant effect of the previous reproductive success on either the breeding dispersal distance or the breeding dispersal probability.Our results indicate that strong breeding site fdelity and short-distance natal dispersal are the dominant dispersal strategies in a patchy population of the western yellow wagtail.展开更多
In this study,we searched for dispersed repeats(DRs)in the rice(Oryza sativa)genome using the iterative procedure(IP)method.The results revealed that the O.sativa genome contained 79 DR families,comprising 992739 DNA ...In this study,we searched for dispersed repeats(DRs)in the rice(Oryza sativa)genome using the iterative procedure(IP)method.The results revealed that the O.sativa genome contained 79 DR families,comprising 992739 DNA repeats,of which 496762 and 495977 were identified on the forward and reverse DNA strands,respectively.The detected DRs were,on average,374 bp in length and occupied 66.4%of the O.sativa genome.Totally 61%of DRs,identified by the IP method,overlapped with previously annotated dispersed repeats(ADRs)detected using the Extensive De Novo TE Annotator(EDTA)pipeline.展开更多
This study explores the adaptation of microbial enzymatic techniques,which were originally developed to eliminate amino impurities in alcoholic beverages,for stabilizing strongly alkaline sodium-based dispersive soils...This study explores the adaptation of microbial enzymatic techniques,which were originally developed to eliminate amino impurities in alcoholic beverages,for stabilizing strongly alkaline sodium-based dispersive soils from check dams.Employing acid urease from Lactobacillus reuteri(L.reuteri)and a control group using soybean-derived urease,this research aimed to modify soil alkalinity through biomineralization.Ultraviolet(UV)mutagenesis optimized L.reuteri strains for biomass and activity.Solution experiments were conducted to assess the effects of pH,temperature,and storage duration on urease activity and to evaluate the calcium carbonate production and crystal morphology of the two ureases under varying calcium ion concentrations.Dispersivity identificationtests and tensile strength evaluations were conducted to analyze the disparities in the modifieddispersive soil treated with the two types of ureases.The results showed that soybean urease should be stored under low-temperature conditions and a neutral pH,whereas acid urease from L.reuteri can be stored at room temperature across a range of pH levels.Both urease treatments effectively reduced soil dispersivity and improved tensile strength significantly(up to 94%and 177%,respectively),with acid urease from L.reuteri resulting in superior soil strengthening and ammonia regulation.These findingssuggest that treating alkaline dispersive soils with acid urease is an efficientand eco-friendly method.展开更多
文摘Dispersals,colonisation,immigration and population assimilation or replacement are fundamental themes in the Palaeolithic record of East Asia.Some of these issues can be studied within a biogeographic framework that explains why and how the distribution of hominin species changed over time and space in response to climatic and environmental change.Because hominins(and especially humans)can change their behaviour through technical,social and cognitive developments,biogeographic models also have to incorporate this factor when investigating dispersals.This is particularly important with the dispersals in East Asia by Homo sapiens into rainforests,across open sea to off-shore islands,to the Arctic and the highest parts of the Tibetan Plateau.This paper suggests how hominin and human dispersals in East Asia might be investigated by using a biogeographic framework that can incorporate changes in hominin adaptability and behaviour.
基金Supported by“Continuation”Project of Excellent Doctors,Guangdong Basic and Applied Basic Research Foundation,No.2025A04J5082Guangdong Basic and Applied Basic Research Foundation,No.2024A1515011236.
文摘This letter addresses challenges in the clinical translation of BIBR1532,a promising telomerase inhibitor,for the treatment of esophageal squamous cell carcinoma(ESCC).BIBR1532 exerts its anti-cancer effect by activating DNA damage response(ATR/CHK1 and ATM/CHK2)pathways and downregulating telomere-binding proteins.Although its therapeutic potential is limited by poor aqueous solubility,solid dispersion(SD)technology may overcome this obstacle.Systematic analysis using PubChem-derived simplified molecular input line entry system identifiers and artificial intelligence-driven FormulationDT platform evaluation(oral formulation feasibility index:0.38)revealed that the SD technology,with superior scalability(32 approved products by 2021)and lower production risks,outperforms lipid-based formulations as an optimal dissolution strategy.Material analysis revealed hydroxypropyl methylcellulose(HPMC)as the optimal carrier with lower hygroscopicity,higher temperature and no intestinal targeting,thus enabling ESCC therapy.HPMC-based SD enhances BIBR1532 solubility and bioavailability for effective ESCC treatment.Future studies should focus on pilot tests for SD fabrication.
基金financial support of the National Natural Science Foundation of China(No.52371103)the Fundamental Research Funds for the Central Universities,China(No.2242023K40028)+1 种基金the Open Research Fund of Jiangsu Key Laboratory for Advanced Metallic Materials,China(No.AMM2023B01).financial support of the Research Fund of Shihezi Key Laboratory of AluminumBased Advanced Materials,China(No.2023PT02)financial support of Guangdong Province Science and Technology Major Project,China(No.2021B0301030005)。
文摘Oxide dispersion strengthened(ODS)alloys are extensively used owing to high thermostability and creep strength contributed from uniformly dispersed fine oxides particles.However,the existence of these strengthening particles also deteriorates the processability and it is of great importance to establish accurate processing maps to guide the thermomechanical processes to enhance the formability.In this study,we performed particle swarm optimization-based back propagation artificial neural network model to predict the high temperature flow behavior of 0.25wt%Al2O3 particle-reinforced Cu alloys,and compared the accuracy with that of derived by Arrhenius-type constitutive model and back propagation artificial neural network model.To train these models,we obtained the raw data by fabricating ODS Cu alloys using the internal oxidation and reduction method,and conducting systematic hot compression tests between 400 and800℃with strain rates of 10^(-2)-10 S^(-1).At last,processing maps for ODS Cu alloys were proposed by combining processing parameters,mechanical behavior,microstructure characterization,and the modeling results achieved a coefficient of determination higher than>99%.
基金supported by China Postdoctoral Science Foundation(Grant No.2019M660047)supported by National Natural Science Foundation of China(Grant Nos.11731005 and 11671180)supported by National Science Foundation of USA(Grant No.DMS-1853622)。
文摘This paper studies an epidemic model with nonlocal dispersals.We focus on the influences of initial data and nonlocal dispersals on its spatial propagation.Here,initial data stand for the spatial concentrations of the infectious agent and the infectious human population when the epidemic breaks out and the nonlocal dispersals mean their diffusion strategies.Two types of initial data decaying to zero exponentially or faster are considered.For the first type,we show that spreading speeds are two constants whose signs change with the number of elements in some set.Moreover,we find an interesting phenomenon:the asymmetry of nonlocal dispersals can influence the propagating directions of the solutions and the stability of steady states.For the second type,we show that the spreading speed is decreasing with respect to the exponentially decaying rate of initial data,and further,its minimum value coincides with the spreading speed for the first type.In addition,we give some results about the nonexistence of traveling wave solutions and the monotone property of the solutions.Finally,some applications are presented to illustrate the theoretical results.
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDB26000000 and XDA20070203)the National Natural Science Foundation of China(Grant Nos.42102001,41430102,41872001,41872005 and 41772018)+2 种基金Key Frontier Science Research Program of the Chinese Academy of Sciences(Grant Nos.QYZDY-SSW-DQC-22 and GJHZ1885)China Scholarship CouncilFrick Fund,Division of Vertebrate Paleontology,AMNH.
文摘Mammals have high dispersal ability,and many lineages can spread across the continents when a landbridge appears.Here,we summarize the dispersal of mammals between the Old and New World at the end of the Miocene.Our analysis suggested that the three phases of dispersal represented the largest dispersal tide during the Neogene,and the direction of dispersal is dominated by being from the Old to New World.Judging from the components that crossed the dispersal corridor,the Arctic environment near the Beringia corridor in the first phase(~7.5 Ma)is a mixed environment,and in the second phase(~6.5 Ma)is an open environment,and in the third phase(~5.8 Ma and continue to the Pliocene)is a wooded(closed)environment.A clear trend of eastern Asian humidification driven by Asian monsoon and the global C4 grassland expansion explain this dispersal pattern.The boost of mammalian dispersals is controlled by the heterogeneity of environmental changes in different continents.
基金National Natural Science Foundation of China(No.41830110)National Key Research Development Program of China(No.2018YFC1503603)+2 种基金State Scholarship Fund from the Chinese Scholarship Council(No.202206710096)Project of China Railway Corporation(No.2021-key-14,2021-major-08)The Joint Planning of Technology and Water Conservancy of Jiangxi Province(No.2022KSG01009).
文摘River embankments are designed to defend against floods over coastal and riparian areas.It is important to early detect unexpected damages on embankments before they exacerbate.To continuously monitor the stability of the embankments and efficiently recognize such potential damages,this study takes SAR(Synthetic Aperture Radar)derived deformation as an indicator of the embankment instability,and customizes a multi-temporal InSAR(Interferometric SAR)approach-small baseline subset.Specifically,during InSAR processing,we apply a two-step amplitude difference dispersion threshold method to extract InSAR measurement points,thus improving the point density within the embankment.We applied this method to the Kangshan Embankment(KE)using 147 Sentinel-1 acquired between 2017 and 2021.We categorized KE into Waterside Slope(WS),Embankment Top(ET),and Landside Slope(LS)using InSAR height estimation.Given the dominance of downslope movement,we developed a projection matrix from InSAR-derived deformation in the satellite line-of-sight direction onto WS and LS.The study shows that KE was generally stable during the five-year period,while WS,ET,and LS experienced different deformation processes.For instance,seasonal variation was observed from the deformation time series,especially between every April and November.We applied the principal component analysis to the time-series displacement and analyzed the results in conjunction with the rainfall data of Kangshan Township.It showed that deformation due to rainfall equals 80.93%,81.30%,and 82.46%of the total deformation for WS,ET,and LS,respectively,indicating that rainfall is one of the environmental driving factors affecting the deformations.We conclude that the proposed methodology is suited for systematic embankment monitoring and identifies major driving forces.
基金Lin Du acknowledges the financial support provided by China Scholarship Council(CSC)via a Ph.D.Scholarship(202008510128)supported by Core Technology Project of China National Petroleum Corporation(CNPC)"Research on Thermal Miscible Flooding Technology"(2023ZG18)。
文摘CO_(2)-responsive gels,which swell upon contact with CO_(2),are widely used for profile control to plug high-permeability gas flow channels in carbon capture,utilization,and storage(CCUS)applications in oil reser-voirs.However,the use of these gels in high-temperature CCUS applications is limited due to their rever-sible swelling behavior at elevated temperatures.In this study,a novel dispersed particle gel(DPG)suspension is developed for high-temperature profile control in CCUS applications.First,we synthesize a double-network hydrogel consisting of a crosslinked polyacrylamide(PAAm)network and a crosslinked sodium alginate(SA)network.The hydrogel is then sheared in water to form a pre-prepared DPG suspen-sion.To enhance its performance,the gel particles are modified by introducing potassium methylsilan-etriolate(PMS)upon CO_(2) exposure.Comparing the particle size distributions of the modified and pre-prepared DPG suspension reveals a significant swelling of gel particles,over twice their original size.Moreover,subjecting the new DPG suspension to a 100℃ environment for 24 h demonstrates that its gel particle sizes do not decrease,confirming irreversible swelling,which is a significant advantage over the traditional CO_(2)-responsive gels.Thermogravimetric analysis further indicates improved thermal sta-bility compared to the pre-prepared DPG particles.Core flooding experiments show that the new DPG suspension achieves a high plugging efficiency of 95.3%in plugging an ultra-high permeability sandpack,whereas the pre-prepared DPG suspension achieves only 82.8%.With its high swelling ratio,irreversible swelling at high temperatures,enhanced thermal stability,and superior plugging performance,the newly developed DPG suspension in this work presents a highly promising solution for profile control in high-temperature CCUS applications.
基金supported by the Guangdong Basic and Applied Basic Research Foundation (No.2023A1515010093)the Shenzhen Fundamental Research Program (Stable Support Plan Program)(Nos.JCYJ20220809170611004, 20231121110828001 and 20231121113641002)the National Taipei University of Technology-Shenzhen University Joint Research Program (No.2024001)。
文摘In this paper, we have demonstrated an Er-doped ultrafast laser with a single mode fiber-gradient index multimode fiber-single mode fiber(SMF-GIMF-SMF, SMS) structure as saturable absorber(SA), which can generate not only stable single-pulse state, but also special mode-locked pulses with the characteristics of high energy and noisy behaviors at proper pump power and cavity polarization state. In addition, we have deeply investigated the real-time spectral evolutions of the mode-locked pulses through the dispersive Fourier transformation(DFT) technique. It can be found that the pulse regime can actually consist of a lot of small noise pulses with randomly varying intensities. We believe that these results will further enrich the nonlinear dynamical processes in the ultrafast lasers.
基金supported by the National Natural Science Foundation of China (NSFC) through Grant Number 42074193
文摘Theoretical analysis has demonstrated that the dispersion relation of chorus waves plays an essential role in the resonant interaction and energy transformation between the waves and magnetospheric electrons.Previous quantitative analyses often simplified the chorus dispersion relation by using the cold plasma assumption.However,the applicability of the cold plasma assumption is doubtful,especially during geomagnetic disturbances.We here present a systematic statistical analysis on the validity of the cold plasma dispersion relation of chorus waves based on observations from the Van Allen Probes over the period from 2012 to 2018.The statistical results show that the observed magnetic field intensities deviate substantially from those calculated from the cold plasma dispersion relation and that they become more pronounced with an increase in geomagnetic activity or a decrease in background plasma density.The region with large deviations is mainly concentrated in the nightside and expands in both the radial and azimuthal directions as the geomagnetic activity increases or the background plasma density decreases.In addition,the bounce-averaged electron scattering rates are computed by using the observed and cold plasma dispersion relation of chorus waves.Compared with usage of the cold plasma dispersion relation,usage of the observed dispersion relation considerably lowers the minimum resonant energy of electrons and lowers the scattering rates of electrons above tens of kiloelectronvolts but enhances those below.Furthermore,these differences are more pronounced with the enhancement of geomagnetic activity or the decrease in background plasma density.
基金National Key Research and Development Program of China(2022YFE03140002,2019YFE03110200)National Natural Science Foundation of China(52273320,52173303,52325103,52171084)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0470000)Anhui Provincial Natural Science Foundation(2308085J07)HFIPS Director's Fund(YZJJ202102,YZJJQY202306,YZJJKX202202)。
文摘93W-4.9Ni-2.1Fe alloys strengthened by nanoscale ZrC particles were prepared by spark-plasma-sintering(SPS)and hot rotary swaging,separately.Results show that the addition of a small number of ZrC nanoparticles can refine grains and increase the hardness of the WNiFe alloys,but hinder the formation of theγ-(Ni,Fe)phase during SPS.SPSed WNiFe and WNiFe-ZrC alloys are brittle at room temperature,while the swaged WNiFe and WNiFe-0.5ZrC(wt%)alloys are ductile.At 400°C,the swaged WNiFe-0.5ZrC alloy exhibits both higher tensile strength and better ductility than the swaged WNiFe.The nanoscale particles distributed in the W grains andγ-(Ni,Fe)phase provide a good pinning effect,which enhances the strength.The thermal conductivity of swaged WNiFe-0.5ZrC is only 71 W·m^(-1)·K^(-1)at room temperature,but it increases to about 100 W·m^(-1)·K^(-1)at 800°C,which is close to that of pure W(121 W·m^(-1)·K^(-1)).These results show the potential of WNiFe alloys as plasma-facing materials in fusion reactor.
基金National Natural Science Foundation of China(51704257,52174350)Hunan Provincial Science and Technology Innovation Program(2024AQ2039)。
文摘Fine nickel powders with a narrow particle size distribution were prepared by reducing nickel hydroxide in aqueous solution.The formation and reduction pathways of nickel powder were analyzed,as well as the effects of the molar ratio of hydrazine hydrate to nickel hydroxide,hydrazine concentration,and the dosage of surfactant PEG6000 on particle size,surface morphology,and dispersion.Results reveal that the nickel particle nucleation occurs on the nickel hydroxide surface,and the nickel hydroxide gradually dissolves during the reaction.With the increase in molar ratio of hydrazine hydrate to nickel hydroxide,the nickel particle size is initially decreased and then increased.Higher hydrazine hydrate concentrations result in smaller particle sizes.A small amount of PEG6000 surfactant can improve dispersion of nickel particles,but a higher amount of PEG6000 surfactant results in the maintenance of the morphology of nickel hydroxide.Adjusting the surfactant dosage can control the average particle size between 1-2μm.
文摘Graphene and its derivatives are two-dimensional nanomaterials with exceptional physical and chemical properties.Research has shown that their addition can counter the inherent deficiencies of cementbased composites,including low tensile strength,poor toughness,and high susceptibility to cracking.However,because of its high specific surface area and the van der Waals force between layers,graphene is prone to agglomerate in the cement matrix which can make the properties worse.Hence,improving the graphene dispersion is essential.The surface structure and properties of graphene and its derivatives are first introduced,and the different methods for their dispersion in cement-based materials are reviewed.Their effects on the mechanical properties and durability of cement-based materials are then summarized.Based on these results,the microscopic and nanoscopic mechanisms of the way graphene and its derivatives affect cement-based materials are elaborated.Current problems and future trends in this research area are then considered.
文摘For segmented detectors,surface flatness is critical as it directly influences both energy resolution and image clarity.Additionally,the limited adjustment range of the segmented detectors necessitates precise benchmark construction.This paper proposes an architecture for detecting detector flatness based on channel spectral dispersion.By measuring the dispersion fringes for coplanar adjustment,the final adjustment residual is improved to better than 300 nm.This result validates the feasibility of the proposed technology and provides significant technical support for the development of next-generation large-aperture sky survey equipment.
基金supported by the Natural Science Foundation of Guangdong Province(2024A1515010908,2025A1515011103)Opening Project of Hubei Key Laboratory of Plasma Chemistry and Advanced Materials(2024P11)+2 种基金Postdoctoral Fellowship Program of CPSF(GZC20233104)National Natural Science Foundation of China(22202087)Opening Project of Hubei Key Laboratory of Biomass Fibers and Eco-Dyeing&Finishing(STRZ202418)。
文摘Catalytic oxidation desulfurization(CODS)technology has shown great promise for diesel desulfurization by virtue of its low cost,mild reaction conditions,and superior desulfurization performance.Herein,a series of FeMoO_(x)/LaTiO_(y)-z samples with diverse Fe/Mo ratios were prepared via a facile citric acid-assisted method.The impact of Fe incorporation on the dispersion and surface elemental states of Mo species,as well as oxygen species content of the synthesized FeMoO_(x)/LaTiO_(y)-z catalysts were systematically characterized using TEM,BET,UV-vis DRS,XPS,XANES,and reaction kinetics,and their CODS performances were examined for 4,6-DMDBT removal.Experimental results demonstrated that Fe/Mo ratio significantly affected the Ti−O bond strength,surface dispersion and electronic structure of Mo O_(2)species on FeMoO_(x)/LaTiO_(y)-z catalysts.FeMoO_(x)/LaTiO_(y)-2 catalyst showed outstanding cycling durability and the best CODS performance with almost 100%removal of 4,6-DMDBT from model oil within 75 min due to its proper MoO3 dispersion,optimal redox property,and the most oxygen vacancy concentration.Nevertheless,further enhancing Fe content led to the increased dispersion of Mo species,while the decrease active Mo species as well as the increase of steric effect for 4,6-DMDBT accessing to the catalytic reactive sites considerably increase the apparent activation energy of FeMoO_(x)/LaTiO_(y)-z(z>2)catalysts during the CODS process,thereby seriously suppressing their CODS performances.Moreover,Radical trapping experiments reveal that the·,generated by the activation of O_(2)at the active sites,catalytic oxidized 4,6-DMDBT to the product of 4,6-DMDBTO_(2),thereby enabling both deep desulfurization and recovery of high-value 4,6-DMDBTO_(2).These findings offer an alternative strategy to achieve ultra deep desulfurization as well as separate and recover high economic value sulfone substances from diesel.
基金supported by the Russian Science Foundation(grant number 23-24-00042).
文摘Dispersal is an important life history trait with signifcant consequences for spatially structured populations,as the exchange of individuals between habitat patches is crucial for maintaining metapopulation connectivity.In this study,we used a long-term data set(2005–2023)to describe dispersal patterns in a patchy population of the Western Yellow Wagtail Motacilla fava within a large(approximately 1,300 km2)study area in the boreal zone of European Russia.We quantifed dispersal distances for birds that dispersed outside their natal or breeding habitat patches and applied a multistate capture–recapture approach to estimate natal and breeding dispersal probabilities.Of 395 adult wagtails and 1,610 nestlings ringed,3%of birds ringed as adults and 3%of birds ringed as nestlings were resighted outside their natal or breeding patches.The probability of natal dispersal(0.29±0.05)was signifcantly higher than the probability of breeding dispersal(0.05±0.01).The median natal dispersal distances(2.8 km for males,3.9 km for females)were the same as the median breeding dispersal distances(2.7 km for males,3.9 km for females).We did not fnd a signifcant effect of the fedging date on either the natal dispersal distance or the natal dispersal probability.Similarly,we did not fnd a signifcant effect of the previous reproductive success on either the breeding dispersal distance or the breeding dispersal probability.Our results indicate that strong breeding site fdelity and short-distance natal dispersal are the dominant dispersal strategies in a patchy population of the western yellow wagtail.
基金supported by the Russian Science Foundation,Russia(Grant No.24-24-00031).
文摘In this study,we searched for dispersed repeats(DRs)in the rice(Oryza sativa)genome using the iterative procedure(IP)method.The results revealed that the O.sativa genome contained 79 DR families,comprising 992739 DNA repeats,of which 496762 and 495977 were identified on the forward and reverse DNA strands,respectively.The detected DRs were,on average,374 bp in length and occupied 66.4%of the O.sativa genome.Totally 61%of DRs,identified by the IP method,overlapped with previously annotated dispersed repeats(ADRs)detected using the Extensive De Novo TE Annotator(EDTA)pipeline.
基金financiallysupported by the National Natural Science Foundation of China(Grant Nos.52079116,52108343,and 51579215).
文摘This study explores the adaptation of microbial enzymatic techniques,which were originally developed to eliminate amino impurities in alcoholic beverages,for stabilizing strongly alkaline sodium-based dispersive soils from check dams.Employing acid urease from Lactobacillus reuteri(L.reuteri)and a control group using soybean-derived urease,this research aimed to modify soil alkalinity through biomineralization.Ultraviolet(UV)mutagenesis optimized L.reuteri strains for biomass and activity.Solution experiments were conducted to assess the effects of pH,temperature,and storage duration on urease activity and to evaluate the calcium carbonate production and crystal morphology of the two ureases under varying calcium ion concentrations.Dispersivity identificationtests and tensile strength evaluations were conducted to analyze the disparities in the modifieddispersive soil treated with the two types of ureases.The results showed that soybean urease should be stored under low-temperature conditions and a neutral pH,whereas acid urease from L.reuteri can be stored at room temperature across a range of pH levels.Both urease treatments effectively reduced soil dispersivity and improved tensile strength significantly(up to 94%and 177%,respectively),with acid urease from L.reuteri resulting in superior soil strengthening and ammonia regulation.These findingssuggest that treating alkaline dispersive soils with acid urease is an efficientand eco-friendly method.
