Green ammonia,produced by harnessing renewable solar energy to split nitrogen,plays a pivotal role in both agricultural practices and forthcoming energy configurations,driving the sustainable development of human soci...Green ammonia,produced by harnessing renewable solar energy to split nitrogen,plays a pivotal role in both agricultural practices and forthcoming energy configurations,driving the sustainable development of human society with zero-carbon emissions.However,nitrogen photoreduction currently faces the challenges of poor activation ability and low yield,and it is still challenging to unravel the intertwined problems in this field and provide direction for its development due to the complex reaction mechanism and multidisciplinary aspects such as photochemistry,catalysis,interface science,and technology.This review focuses on capturing the latest advances in photocatalytic nitrogen-to-ammonia conversion,delving into fundamental principles regarding the process,efficient photocatalysts for practical ammonia synthesis,and well-designed catalytic environments.Besides,this article provides insightful guidelines for analyzing complicated reaction mechanisms and identifying key bottlenecks or specific rate-determining steps,such as reactant activation,interfacial reaction engineering,and hydrogen evolution side reactions.By integrating perspectives from atomic mechanisms,nanoscale photocatalysts,microscale interfacial engineering,and macroscale reaction system design,this review advances the development of nitrogen photoreduction from proof-of-concept discoveries to viable solar-to-chemical conversion technologies,while also providing a valuable entry point for researchers into this burgeoning field.展开更多
The interfacial structure and its regulation play a crucial role in determining the overall performance of advanced functional composites.Weak interfacial interactions between carbon fibers and the matrix present a cr...The interfacial structure and its regulation play a crucial role in determining the overall performance of advanced functional composites.Weak interfacial interactions between carbon fibers and the matrix present a critical challenge limiting the general performance and functional applications of carbon fiberreinforced composites.In this paper,a novel strategy for bioinspired root-soil interfacial structure was presented to enhance the mechanical properties of polymer bonded explosives.A multiscale nanowire heterostructure was constructed through the in-situ growth of morphologically controllable zinc oxide nanowires on the carbon fiber surface via a facile hydrothermal method,with polydopamine as the interfacial reinforcement layer.This structure emulated the function of the"root",and combined with a network-distributed polymer binder representing the"soil",formed a robust root-soil interlocking interfacial structure within the polymer bonded explosives.Due to the multiscale interfacial reinforcement structure,the tensile strength of the polymer bonded explosives was visibly increased by 41%,the strain at the break by 110%,and the creep resistance by 51%with only 0.4 wt%filler adopted.The thermal stress resistance was improved by 57%owing to the synergistic enhancement of thermal conductivity and mechanical properties.This study provides new perspectives and insights for designing and constructing high-performance polymer bonded explosives and other functional composites.展开更多
Wavelength division multiplexing technology has been pivotal in addressing the demand for high-capacity optical communication with silicon photonics providing a promising platform. This work presents a 16-channel wave...Wavelength division multiplexing technology has been pivotal in addressing the demand for high-capacity optical communication with silicon photonics providing a promising platform. This work presents a 16-channel wavelength division multiplexing silicon photonics receiver chip composed of an arrayed waveguide grating and Ge-on-Si photodetectors. Integrated inductors are introduced to enhance the high-speed performance of photodetectors, enabling data rates up to 112 Gbps with high responsivity and low dark current. The operating wavelength range of the arrayed wavelength grating is adjusted according to the response of the Ge-on-Si photodetector. The optical insertion loss, cross talk and central wavelength of the array waveguide grating are 2.1 to 3.7 d B,-12 to-15 d B, and 1538 nm, respectively. The proposed receiver chip offers a solution to meet the challenges of modern data transmission requirements.展开更多
Enhancing soil organic carbon(SOC)stocks is a key aspect of modern agriculture,but whether this can be achieved by incorporating legume green manure crops in cereal production to substitute synthetic N fertilizers is ...Enhancing soil organic carbon(SOC)stocks is a key aspect of modern agriculture,but whether this can be achieved by incorporating legume green manure crops in cereal production to substitute synthetic N fertilizers is unknown.This study used a six-year(2017-2022)field study to explore the impacts of intercropping green manure with maize and reducing nitrogen fertilization on SOC stocks,while specifically focusing on the relationship between aggregate composition and carbon sequestration.Maize intercropped with common vetch(M/V),maize intercropped with rapeseed(M/R),and sole maize(M),were each tested at conventional(N2,360 kg ha^(-1))and reduced(N1,270 kg ha^(-1),25% reduced)N application rates.Soil was sampled in 2020,2021,and 2022.Compared with sole maize,intercropping with green manure(M/V and M/R)significantly increased SOC stocks which compensated for any negative effect due to the 25% reduction in N application.Based on 3-year averages,intercropping with M/V and M/R increased the SOC content compared to sole maize(M)by 12.1 and 9.1%,respectively,with intercropping further mitigating the negative impact of reduced nitrogen application.There was no significant difference between M/V and M/R.The SOC content at N1 was reduced by 9.3-10.5%compared to that at N2 in sole maize,but the differences in SOC stocks between N1 and N2 were not significant in the intercropping patterns(M/V and M/R).The intercropped M/V and M/R showed 20.9 and 16.3% higher SOC contents compared to sole maize at N1,with no differences at N2.Intercropping green manure led to a 5.3% greater SOC in the 0-20 cm depth soil in 2022 compared to that in 2020,due to the cumulative effect of two years of green manure intercropping.Intercropping green manure(M/V and M/R)increased the proportion of macroaggregates(>0.25 mm)and aggregate stability while reducing the proportion of microaggregates compared to sole maize under the N1 application.Structural equation modeling indicated that cropping patterns and nitrogen application levels mainly affect SOC indirectly by regulating the composition of macroaggregates and aggregate organic carbon(AOC).Correlation analysis further revealed that the composition of macroaggregates is significantly and positively correlated with the SOC content(R^(2)=0.64).In addition,intercropping green manure can maintain high crop yields by increasing SOC under reduced chemical nitrogen application.The results of this study show that intercropping green manure with grain crops can be a viable measure for increasing SOC sinks and maize productivity by optimizing the aggregate composition with reduced N application in the Hexi Oasis Irrigation Area.展开更多
Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challe...Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challenges.In this work,we demonstrate for the firs time that the coherent radiation farfiel patterns from laser–foil interactions can serve as an in situ,real-time,and easy-to-implement diagnostic for an ultraintense laser focus.The laser-driven electron sheets,curved by the spatially varying laser fiel and leaving the targets at nearly the speed of light,produce doughnut-shaped patterns depending on the shapes of the focal spot and the absolute laser intensities.Assisted by particle-in-cell simulations,we can achieve measurements of the intensity and the focal spot,and provide immediate feedback to optimize the focal spots for extremely high intensity.展开更多
The limited corrosion resistance of Mg-Li alloys restricts their applications.This study investigates the en-hancement of corrosion resistance in LAZ931 alloy through the application of a composite MAO/NaMgF_(3) coati...The limited corrosion resistance of Mg-Li alloys restricts their applications.This study investigates the en-hancement of corrosion resistance in LAZ931 alloy through the application of a composite MAO/NaMgF_(3) coating via a two-step process,encompassing MAO pretreatment followed by caffeic acid-induced NaMgF_(3) chemical deposition.The enhanced corrosion resistance is attributed to the homogenization of the MAO coating and the in-situ sealing of pores by NaMgF_(3) on the Mg surface.The incorporation of caffeic acid facilitates the formation of NaMgF_(3).Furthermore,it is observed that samples treated with this composite coating demonstrate robust ultraviolet light absorption capabilities and can emit visible light when excited by near-ultraviolet light.This unique characteristic expands the potential applications of this coating technology in the aerospace industry.This research offers novel perspectives on the design and preparation of composite coatings for magnesium alloys,holding great promise for broadening the application scope of Mg-Li alloys.展开更多
Structural components usually require inexpensive materials with ultrahigh strength,large ductility,and low density,which are still lacking and being searched.We hereby develop a partially recrystallized(Rexed)low-den...Structural components usually require inexpensive materials with ultrahigh strength,large ductility,and low density,which are still lacking and being searched.We hereby develop a partially recrystallized(Rexed)low-density steel having unprecedentedly ultrahigh specific yield strength and large ductility at the same time.The former results from both dislocation hardening in unRexed grains and the significant precipitation hardening of κ-carbides having the sizes of several,tens of and hundreds of nanometers in the Rexed,unRexed grains and at boundaries,respectively.Particularly,the κ-carbides within Rexed grains can grow toward the critical sizes for the maximum cutting-through precipitation hardening during the optimal ageing process,which can be guided by ab initio calculations;consequently,the strength difference between the Rexed and unRexed grains is minimized so that they can deform more compatibly.In addition,the presence of ductile precipitation-free zones close to the discrete intergranular κ-carbides reduces the tendency to the brittle intergranular cracking.A nearly half Rexed microstructure may provide the possibly largest quantity of Rexed/unRexed grain boundaries for the maximum heterodeformation-induced strain-hardening,contributing to large ductility.Therefore,we propose that such a hierarchical precipitation in a nearly half Rexed matrix may be a new microstructural strategy for manufacturing ultrastrong lightweight alloys.展开更多
The common vetch(Vicia sativa L.)is a self-pollinated annual forage legume that is widely distributed worldwide.It has wide adaptability and high nutritional value and is commonly used as an important protein source f...The common vetch(Vicia sativa L.)is a self-pollinated annual forage legume that is widely distributed worldwide.It has wide adaptability and high nutritional value and is commonly used as an important protein source for livestock feed.However,pod shattering seriously limits the yield of common vetch.To clarify the mechanism of pod shattering in common vetch,the pod walls of three shattering-resistant(SR)accessions(B65,B135,and B392)and three shattering-susceptible(SS)accessions(L33,L170,and L461)were selected for transcriptome sequencing.A total of 17,190 differentially expressed genes(DEGs)were identified in the pod wall of B135 and L461 common vetch at 5,10,15,20,and 25 days after anthesis.Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis showed that“phenylpropanoid biosynthesis”was the most significantly enriched pathway,and 40 structural genes associated with lignin biosynthesis were identified and differentially expressed in B135 and L461 common vetch.We analysed the DEGs in the pod wall of three SR and three SS accessions at 15 days after anthesis,and most of the DEGs were consistent with the significant enrichment pathways identified in B135 and L461 common vetch.The total lignin content of SR accessions was significantly lower than the SS accessions.The present study lays a foundation for understanding the molecular regulatory mechanism of pod shattering related to lignin biosynthesis in common vetch and provides reference functional genes for breeders to further cultivate shattering-resistant common vetch varieties.展开更多
Background:Type 2 diabetes(T2D)accounts for the majority of diabetes incidences and remains a widespread global chronic disorder.Apart from early lifestyle changes,intervention options for T2D are mainly pharmaceutica...Background:Type 2 diabetes(T2D)accounts for the majority of diabetes incidences and remains a widespread global chronic disorder.Apart from early lifestyle changes,intervention options for T2D are mainly pharmaceutical.Methods:Repetitive transcranial magnetic stimulation(rTMS)has been approved by the FDA as a therapeutic intervention option for major depressive disorders,with further studies also indicating its role in energy metabolism and appetite.Considering its safe and non-invasive properties,we evaluated the effects of rTMS on systemic metabolism using T2D rats.Results:We observed that rTMS improved glucose tolerance and insulin sensitivity in T2D rats after a 10-day exposure.Improved systemic insulin sensitivity was main-tained after a 21-day treatment period,accompanied by modest yet significant weight loss.Circulating serum lipid levels,including those of cholesteryl ester,tryglyceride and ceramides,were also reduced following rTMS application.RNA-seq analyses fur-ther revealed a changed expression profile of hepatic genes that are related to sterol production and fatty acid metabolism.Altered expression of hypothalamic genes that are related to appetite regulation,neural activity and ether lipid metabolism were also implicated.Conclusion:In summary,our data report a positive impact of rTMS on systemic insu-lin sensitivity and weight management of T2D rats.The underlying mechanisms via which rTMS regulates systemic metabolic parameters partially involve lipid utilization in the periphery as well as central regulation of energy intake and lipid metabolism.展开更多
A silicon-based germanium(Ge)photodetector working for C and L bands is proposed in this paper.The device fea-tures a novel asymmetric PIN structure,which contributes to a more optimized electric field distribution in...A silicon-based germanium(Ge)photodetector working for C and L bands is proposed in this paper.The device fea-tures a novel asymmetric PIN structure,which contributes to a more optimized electric field distribution in Ge and a shorter effective width of depleted region.Meanwhile,the optical structure is designed carefully to enhance responsivity for broad-band.Under-7 V,where the weak avalanche process happens,the responsivity of our device is 1.49 and 1.16 A/W at 1550 and 1600 nm,with bandwidth of 47.1 and 44.5 GHz,respectively.These performances demonstrate the significant application poten-tial of the device in optical communication systems.展开更多
In this paper,we study the self-similar solutions of the degenerate diffusion equation ut-div(|▽u^(m)|^(p-2)▽u^(m))=0 of polytropic filtration diffusion in R^(N)×(0,±∞)or(R^(N)/{0})×(0,±∞)with ...In this paper,we study the self-similar solutions of the degenerate diffusion equation ut-div(|▽u^(m)|^(p-2)▽u^(m))=0 of polytropic filtration diffusion in R^(N)×(0,±∞)or(R^(N)/{0})×(0,±∞)with N≥1,m>0,p>1,such that m(p-1)>1.We give a clear classification of the self-similar solutions of the form u(x,t)=(βt)^(-α/β)((βt)^(-1/β)|x|)withα∈R andβ=α[m(p-1)-1]+p,regular or singular at the origin point.The existence and uniqueness of some solutions are established by the phase plane analysis method,and the asymptotic properties of the solutions near the origin and the infinity are also described.This paper extends the classical results of self-similar solutions for degeneratep-Laplace heat equation by Bidaut-Véron[Proc Royal Soc Edinburgh,2009,139:1-43]to the doubly nonlinear degenerate diffusion equations.展开更多
Realizing effective enhancement in the thermally conductive performance of polymer bonded explosives(PBXs) is vital for improving the resultant environmental adaptabilities of the PBXs composites. Herein, a kind of pr...Realizing effective enhancement in the thermally conductive performance of polymer bonded explosives(PBXs) is vital for improving the resultant environmental adaptabilities of the PBXs composites. Herein, a kind of primary-secondary thermally conductive network was designed by water-suspension granulation, surface coating, and hot-pressing procedures in the graphene-based PBXs composites to greatly increase the thermal conductive performance of the composites. The primary network with a threedimensional structure provided the heat-conducting skeleton, while the secondary network in the polymer matrix bridged the primary network to increase the network density. The enhancement efficiency in the thermally conductive performance of the composites reached the highest value of 59.70% at a primary-secondary network ratio of 3:1. Finite element analysis confirmed the synergistic enhancement effect of the primary and secondary thermally conductive networks. This study introduces an innovative approach to designing network structures for PBX composites, significantly enhancing their thermal conductivity.展开更多
Before solar eruptions,a short-term slow-rise phase is often observed,during which the pre-eruption structure ascends at speeds much greater than the photospheric motions but much less than those of the eruption phase...Before solar eruptions,a short-term slow-rise phase is often observed,during which the pre-eruption structure ascends at speeds much greater than the photospheric motions but much less than those of the eruption phase.Numerical magnetohydrodynamic (MHD) simulations of the coronal evolution driven by photospheric motions up to eruptions have been used to explain the slow-rise phase,but their bottom driving speeds are much larger than realistic photospheric values.Therefore,it remains an open question how the excessively fast bottom driving impacts the slow-rise phase.Here we modeled the slow-rise phase before eruption initiated from a continuously sheared magnetic arcade.In particular,we performed a series of experiments with the bottom driving speed unprecedentedly approaching the photospheric value of around 1 km s^(-1).The simulations confirmed that the slowrise phase is an ideal MHD process,i.e.,a manifestation of the growing expansion of the sheared arcade in the process of approaching a fully open field state.The overlying field line above the core flux has a slow-rise speed modulated by the driving speed’s magnitude but is always over an order of magnitude larger than the driving speed.The core field also expands with speed much higher than the driving speed but much lower than that of the overlying field.By incrementally reducing the bottom-driving speed to realistic photospheric values,we anticipate better matches between the simulated slow-rise speeds and some observed ones.展开更多
This study investigated the influence of band microstructure induced by centerline segregation on carbide precipitation behavior and toughness in an 80 mm-thick 1 GPa low-carbon low-alloy steel plate.The quarter-thick...This study investigated the influence of band microstructure induced by centerline segregation on carbide precipitation behavior and toughness in an 80 mm-thick 1 GPa low-carbon low-alloy steel plate.The quarter-thickness(1/4t)and half-thickness(1/2t)regions of the plate exhibited similar ductility and toughness after quenching.After tempering,the 1/4t region exhibited~50%and~25%enhancements in both the total elongation and low-temperature toughness at-40°C,respectively,without a decrease in yield strength,whereas the toughness of the 1/2t region decreased by~46%.After quenching,both the 1/4t and 1/2t regions exhibited lower bainite and lath martensite concentrations,but only the 1/2t region exhibited microstructure bands.Moreover,the tempered 1/4t region featured uniformly dispersed short rod-like M_(23)C_(6)carbides,and spherical MC precipitates with diameters of~20–100 nm and<20 nm,respectively.The uniformly dispersed nanosized M_(23)C_(6)carbides and MC precipitates contributed to the balance of high strength and high toughness.The band microstructure of the tempered 1/2t region featured a high density of large needle-like M3C carbides.The length and width of the large M3C carbides were~200–500 nm and~20–50 nm,respectively.Fractography analysis revealed that the high density of large carbides led to delamination cleavage fracture,which significantly deteriorated toughness.展开更多
With the development of global position system（GPS）,wireless technology and location aware services,it is possible to collect a large quantity of trajectory data.In the field of data mining for moving objects,the pr...With the development of global position system（GPS）,wireless technology and location aware services,it is possible to collect a large quantity of trajectory data.In the field of data mining for moving objects,the problem of anomaly detection is a hot topic.Based on the development of anomalous trajectory detection of moving objects,this paper introduces the classical trajectory outlier detection（TRAOD） algorithm,and then proposes a density-based trajectory outlier detection（DBTOD） algorithm,which compensates the disadvantages of the TRAOD algorithm that it is unable to detect anomalous defects when the trajectory is local and dense.The results of employing the proposed algorithm to Elk1993 and Deer1995 datasets are also presented,which show the effectiveness of the algorithm.展开更多
Orthogonal time frequency space(OTFS),as a novel 2-D modulation technique,has been proposed to achieve better BER performances over delayDoppler channels.In this paper,we propose two different power allocation(PA)algo...Orthogonal time frequency space(OTFS),as a novel 2-D modulation technique,has been proposed to achieve better BER performances over delayDoppler channels.In this paper,we propose two different power allocation(PA)algorithms in OTFS systems with zero forcing(ZF)or minimum mean square error(MMSE)equalization,where general formulas with PA are derived in advance under the condition of minimum BER(MBER)criterion.On one hand,a suboptimal MBER power allocation method is put forward to achieve better BER performances,and then analytical BER expressions are derived with proposed PA strategy.Considering the case of MMSE equalization,a combined subsymbol allocation(SA)and PA strategy is raised,where some subsymbols may be abandoned due to worse channel conditions,and then it is proven effectively to improve BER performances through theoretical and simulation results.Furthermore,BER performances with proposed joint SA and PA strategy are also investigated in delay-Doppler channels,where an improved message passing(MP)receiver based on equivalent channel matrix with PA is given.展开更多
从省份尺度探讨土地利用动态变化及其生态系统服务价值(Ecosystem Service Value,ESV)响应对区域土地利用规划和生态建设评价极为重要。基于宁夏回族自治区2000、2010、2015、2020年4期Landsat ETM+、TM和OLI遥感影像,采用面向对象分类...从省份尺度探讨土地利用动态变化及其生态系统服务价值(Ecosystem Service Value,ESV)响应对区域土地利用规划和生态建设评价极为重要。基于宁夏回族自治区2000、2010、2015、2020年4期Landsat ETM+、TM和OLI遥感影像,采用面向对象分类方法,构建区域2000—2020年土地利用数据库,利用土地利用动态度与ESV指数方法,并构建适用于本区域的单位面积ESV当量,分析了2000—2020年宁夏土地利用转型及其ESV响应过程。结果表明:草地和耕地是宁夏主要的土地利用类型,平均占比分别为44.7%和31.7%,随着生态工程的实施,区域耕地减少,林地和草地增加,而社会经济发展使得建设用地持续扩张。随着土地利用转型,2000—2020年宁夏ESV呈现增加—减小—增加的变化过程,范围为450.9亿~459.1亿元,2010年最高。草地和耕地是宁夏ESV的主要贡献地类,其中草地的ESV贡献为35.9%,明显低于其面积占比,而林地和湿地的ESV贡献高于其面积占比。吴忠市、固原市、中卫市、银川市、石嘴山市对宁夏ESV总量的多年平均贡献依次为29.9%、27.5%、20.5%、14.5%、7.6%。2000—2020年,各地市对全区ESV的贡献比例较为稳定,但由于各类土地利用在地市的分布差异较大,地市各个土地利用类型的ESV对该类总值的贡献发生变化。展开更多
基金financially supported by the National Energy Green Hydrogen Refining Research&Development Center,National Natural Science Foundation of China(No.22476222)Natural Science Funds of Guangdong for Distinguished Young Scholar(No.2022B1515020098).
文摘Green ammonia,produced by harnessing renewable solar energy to split nitrogen,plays a pivotal role in both agricultural practices and forthcoming energy configurations,driving the sustainable development of human society with zero-carbon emissions.However,nitrogen photoreduction currently faces the challenges of poor activation ability and low yield,and it is still challenging to unravel the intertwined problems in this field and provide direction for its development due to the complex reaction mechanism and multidisciplinary aspects such as photochemistry,catalysis,interface science,and technology.This review focuses on capturing the latest advances in photocatalytic nitrogen-to-ammonia conversion,delving into fundamental principles regarding the process,efficient photocatalysts for practical ammonia synthesis,and well-designed catalytic environments.Besides,this article provides insightful guidelines for analyzing complicated reaction mechanisms and identifying key bottlenecks or specific rate-determining steps,such as reactant activation,interfacial reaction engineering,and hydrogen evolution side reactions.By integrating perspectives from atomic mechanisms,nanoscale photocatalysts,microscale interfacial engineering,and macroscale reaction system design,this review advances the development of nitrogen photoreduction from proof-of-concept discoveries to viable solar-to-chemical conversion technologies,while also providing a valuable entry point for researchers into this burgeoning field.
基金supported by the Presidential Foundation of CAEP(No.YZJJZQ2022006)the National Natural Science Foundation of China(Nos.22275173 and 22475179).
文摘The interfacial structure and its regulation play a crucial role in determining the overall performance of advanced functional composites.Weak interfacial interactions between carbon fibers and the matrix present a critical challenge limiting the general performance and functional applications of carbon fiberreinforced composites.In this paper,a novel strategy for bioinspired root-soil interfacial structure was presented to enhance the mechanical properties of polymer bonded explosives.A multiscale nanowire heterostructure was constructed through the in-situ growth of morphologically controllable zinc oxide nanowires on the carbon fiber surface via a facile hydrothermal method,with polydopamine as the interfacial reinforcement layer.This structure emulated the function of the"root",and combined with a network-distributed polymer binder representing the"soil",formed a robust root-soil interlocking interfacial structure within the polymer bonded explosives.Due to the multiscale interfacial reinforcement structure,the tensile strength of the polymer bonded explosives was visibly increased by 41%,the strain at the break by 110%,and the creep resistance by 51%with only 0.4 wt%filler adopted.The thermal stress resistance was improved by 57%owing to the synergistic enhancement of thermal conductivity and mechanical properties.This study provides new perspectives and insights for designing and constructing high-performance polymer bonded explosives and other functional composites.
基金National Key Research and Development Program of China (2022YFB2802400)National Natural Science Foundation of China (62250010, 62090054, 62274160)Youth Innovation Promotion Association of the Chinese Academy of Sciences (2021111)。
文摘Wavelength division multiplexing technology has been pivotal in addressing the demand for high-capacity optical communication with silicon photonics providing a promising platform. This work presents a 16-channel wavelength division multiplexing silicon photonics receiver chip composed of an arrayed waveguide grating and Ge-on-Si photodetectors. Integrated inductors are introduced to enhance the high-speed performance of photodetectors, enabling data rates up to 112 Gbps with high responsivity and low dark current. The operating wavelength range of the arrayed wavelength grating is adjusted according to the response of the Ge-on-Si photodetector. The optical insertion loss, cross talk and central wavelength of the array waveguide grating are 2.1 to 3.7 d B,-12 to-15 d B, and 1538 nm, respectively. The proposed receiver chip offers a solution to meet the challenges of modern data transmission requirements.
基金supported by the National Key Research and Development Program of China(2021YFD1700204)the National Natural Science Foundation of China(U21A20218 and 32372238)+1 种基金the Modern Agro-Industry Technology Research System of China(CARS-22-G-12)the“Innovation Star”Program of Graduate Students in 2025 of Gansu Province,China(2025CXZX-749)。
文摘Enhancing soil organic carbon(SOC)stocks is a key aspect of modern agriculture,but whether this can be achieved by incorporating legume green manure crops in cereal production to substitute synthetic N fertilizers is unknown.This study used a six-year(2017-2022)field study to explore the impacts of intercropping green manure with maize and reducing nitrogen fertilization on SOC stocks,while specifically focusing on the relationship between aggregate composition and carbon sequestration.Maize intercropped with common vetch(M/V),maize intercropped with rapeseed(M/R),and sole maize(M),were each tested at conventional(N2,360 kg ha^(-1))and reduced(N1,270 kg ha^(-1),25% reduced)N application rates.Soil was sampled in 2020,2021,and 2022.Compared with sole maize,intercropping with green manure(M/V and M/R)significantly increased SOC stocks which compensated for any negative effect due to the 25% reduction in N application.Based on 3-year averages,intercropping with M/V and M/R increased the SOC content compared to sole maize(M)by 12.1 and 9.1%,respectively,with intercropping further mitigating the negative impact of reduced nitrogen application.There was no significant difference between M/V and M/R.The SOC content at N1 was reduced by 9.3-10.5%compared to that at N2 in sole maize,but the differences in SOC stocks between N1 and N2 were not significant in the intercropping patterns(M/V and M/R).The intercropped M/V and M/R showed 20.9 and 16.3% higher SOC contents compared to sole maize at N1,with no differences at N2.Intercropping green manure led to a 5.3% greater SOC in the 0-20 cm depth soil in 2022 compared to that in 2020,due to the cumulative effect of two years of green manure intercropping.Intercropping green manure(M/V and M/R)increased the proportion of macroaggregates(>0.25 mm)and aggregate stability while reducing the proportion of microaggregates compared to sole maize under the N1 application.Structural equation modeling indicated that cropping patterns and nitrogen application levels mainly affect SOC indirectly by regulating the composition of macroaggregates and aggregate organic carbon(AOC).Correlation analysis further revealed that the composition of macroaggregates is significantly and positively correlated with the SOC content(R^(2)=0.64).In addition,intercropping green manure can maintain high crop yields by increasing SOC under reduced chemical nitrogen application.The results of this study show that intercropping green manure with grain crops can be a viable measure for increasing SOC sinks and maize productivity by optimizing the aggregate composition with reduced N application in the Hexi Oasis Irrigation Area.
基金supported by the Guangdong High Level Innovation Research Institute(Grant No.2021B0909050006)the National Grand Instrument Project(Grant No.2019YFF01014402)+1 种基金the National Natural Science Foundation of China(Grant No.12205008)support from the National Science Fund for Distinguished Young Scholars(Grant No.12225501)。
文摘Experimental validation of laser intensity is particularly important for the study of fundamental physics at extremely high intensities.However,reliable diagnosis of the focal spot and peak intensity faces huge challenges.In this work,we demonstrate for the firs time that the coherent radiation farfiel patterns from laser–foil interactions can serve as an in situ,real-time,and easy-to-implement diagnostic for an ultraintense laser focus.The laser-driven electron sheets,curved by the spatially varying laser fiel and leaving the targets at nearly the speed of light,produce doughnut-shaped patterns depending on the shapes of the focal spot and the absolute laser intensities.Assisted by particle-in-cell simulations,we can achieve measurements of the intensity and the focal spot,and provide immediate feedback to optimize the focal spots for extremely high intensity.
基金financial support from the Joint Fund Project of Henan Provincial Science and Technology Research and Development Plan(No.242301420036)the National Natural Sci-ence Foundation of China(No.52301107)+1 种基金the Domain Foun-dation of Equipment Advance Research of the 14th Five-year Plan(No.50922010302)supported by the Project of Zhongyuan Critical Metals Laboratory.
文摘The limited corrosion resistance of Mg-Li alloys restricts their applications.This study investigates the en-hancement of corrosion resistance in LAZ931 alloy through the application of a composite MAO/NaMgF_(3) coating via a two-step process,encompassing MAO pretreatment followed by caffeic acid-induced NaMgF_(3) chemical deposition.The enhanced corrosion resistance is attributed to the homogenization of the MAO coating and the in-situ sealing of pores by NaMgF_(3) on the Mg surface.The incorporation of caffeic acid facilitates the formation of NaMgF_(3).Furthermore,it is observed that samples treated with this composite coating demonstrate robust ultraviolet light absorption capabilities and can emit visible light when excited by near-ultraviolet light.This unique characteristic expands the potential applications of this coating technology in the aerospace industry.This research offers novel perspectives on the design and preparation of composite coatings for magnesium alloys,holding great promise for broadening the application scope of Mg-Li alloys.
基金financially supported by the National Natural Science Foundation of China(Nos.52233018 and 51831002)the U.S.National Science Foundation(No.DMR-1611180,1809640,and 2226508)the Army Research Office(Nos.W911NF-13-1-0438 and W911NF-19-2-0049).
文摘Structural components usually require inexpensive materials with ultrahigh strength,large ductility,and low density,which are still lacking and being searched.We hereby develop a partially recrystallized(Rexed)low-density steel having unprecedentedly ultrahigh specific yield strength and large ductility at the same time.The former results from both dislocation hardening in unRexed grains and the significant precipitation hardening of κ-carbides having the sizes of several,tens of and hundreds of nanometers in the Rexed,unRexed grains and at boundaries,respectively.Particularly,the κ-carbides within Rexed grains can grow toward the critical sizes for the maximum cutting-through precipitation hardening during the optimal ageing process,which can be guided by ab initio calculations;consequently,the strength difference between the Rexed and unRexed grains is minimized so that they can deform more compatibly.In addition,the presence of ductile precipitation-free zones close to the discrete intergranular κ-carbides reduces the tendency to the brittle intergranular cracking.A nearly half Rexed microstructure may provide the possibly largest quantity of Rexed/unRexed grain boundaries for the maximum heterodeformation-induced strain-hardening,contributing to large ductility.Therefore,we propose that such a hierarchical precipitation in a nearly half Rexed matrix may be a new microstructural strategy for manufacturing ultrastrong lightweight alloys.
基金supported by the Leading Scientist Project of Qinghai Province,China(2023-NK-147)。
文摘The common vetch(Vicia sativa L.)is a self-pollinated annual forage legume that is widely distributed worldwide.It has wide adaptability and high nutritional value and is commonly used as an important protein source for livestock feed.However,pod shattering seriously limits the yield of common vetch.To clarify the mechanism of pod shattering in common vetch,the pod walls of three shattering-resistant(SR)accessions(B65,B135,and B392)and three shattering-susceptible(SS)accessions(L33,L170,and L461)were selected for transcriptome sequencing.A total of 17,190 differentially expressed genes(DEGs)were identified in the pod wall of B135 and L461 common vetch at 5,10,15,20,and 25 days after anthesis.Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis showed that“phenylpropanoid biosynthesis”was the most significantly enriched pathway,and 40 structural genes associated with lignin biosynthesis were identified and differentially expressed in B135 and L461 common vetch.We analysed the DEGs in the pod wall of three SR and three SS accessions at 15 days after anthesis,and most of the DEGs were consistent with the significant enrichment pathways identified in B135 and L461 common vetch.The total lignin content of SR accessions was significantly lower than the SS accessions.The present study lays a foundation for understanding the molecular regulatory mechanism of pod shattering related to lignin biosynthesis in common vetch and provides reference functional genes for breeders to further cultivate shattering-resistant common vetch varieties.
基金National Key Technologies Research and Development Program of China,Grant/Award Number:2020YFA0803701National Natural Science Foundation of China,Grant/Award Number:52107241,81973699 and 82274361CAMS Innovation Fund for Medical Sciences,Grant/Award Number:2021-12M-1-052。
文摘Background:Type 2 diabetes(T2D)accounts for the majority of diabetes incidences and remains a widespread global chronic disorder.Apart from early lifestyle changes,intervention options for T2D are mainly pharmaceutical.Methods:Repetitive transcranial magnetic stimulation(rTMS)has been approved by the FDA as a therapeutic intervention option for major depressive disorders,with further studies also indicating its role in energy metabolism and appetite.Considering its safe and non-invasive properties,we evaluated the effects of rTMS on systemic metabolism using T2D rats.Results:We observed that rTMS improved glucose tolerance and insulin sensitivity in T2D rats after a 10-day exposure.Improved systemic insulin sensitivity was main-tained after a 21-day treatment period,accompanied by modest yet significant weight loss.Circulating serum lipid levels,including those of cholesteryl ester,tryglyceride and ceramides,were also reduced following rTMS application.RNA-seq analyses fur-ther revealed a changed expression profile of hepatic genes that are related to sterol production and fatty acid metabolism.Altered expression of hypothalamic genes that are related to appetite regulation,neural activity and ether lipid metabolism were also implicated.Conclusion:In summary,our data report a positive impact of rTMS on systemic insu-lin sensitivity and weight management of T2D rats.The underlying mechanisms via which rTMS regulates systemic metabolic parameters partially involve lipid utilization in the periphery as well as central regulation of energy intake and lipid metabolism.
基金supported by National Key Research and Development Program of China(2022YFB2802400)National Natural Science Foundation of China(62250010,62090054,62274160)Youth Innovation Promotion Association of the Chinese Academy of Sciences(2021111).
文摘A silicon-based germanium(Ge)photodetector working for C and L bands is proposed in this paper.The device fea-tures a novel asymmetric PIN structure,which contributes to a more optimized electric field distribution in Ge and a shorter effective width of depleted region.Meanwhile,the optical structure is designed carefully to enhance responsivity for broad-band.Under-7 V,where the weak avalanche process happens,the responsivity of our device is 1.49 and 1.16 A/W at 1550 and 1600 nm,with bandwidth of 47.1 and 44.5 GHz,respectively.These performances demonstrate the significant application poten-tial of the device in optical communication systems.
基金supported by the NSFC(12271178,12171166)the Guangzhou Basic and Applied Basic Research Foundation(2024A04J2022)the TCL Young Scholar(2024-2027).
文摘In this paper,we study the self-similar solutions of the degenerate diffusion equation ut-div(|▽u^(m)|^(p-2)▽u^(m))=0 of polytropic filtration diffusion in R^(N)×(0,±∞)or(R^(N)/{0})×(0,±∞)with N≥1,m>0,p>1,such that m(p-1)>1.We give a clear classification of the self-similar solutions of the form u(x,t)=(βt)^(-α/β)((βt)^(-1/β)|x|)withα∈R andβ=α[m(p-1)-1]+p,regular or singular at the origin point.The existence and uniqueness of some solutions are established by the phase plane analysis method,and the asymptotic properties of the solutions near the origin and the infinity are also described.This paper extends the classical results of self-similar solutions for degeneratep-Laplace heat equation by Bidaut-Véron[Proc Royal Soc Edinburgh,2009,139:1-43]to the doubly nonlinear degenerate diffusion equations.
基金supported by the National Natural Science Foundation of China (Grant Nos. 22475179 and 22275173)。
文摘Realizing effective enhancement in the thermally conductive performance of polymer bonded explosives(PBXs) is vital for improving the resultant environmental adaptabilities of the PBXs composites. Herein, a kind of primary-secondary thermally conductive network was designed by water-suspension granulation, surface coating, and hot-pressing procedures in the graphene-based PBXs composites to greatly increase the thermal conductive performance of the composites. The primary network with a threedimensional structure provided the heat-conducting skeleton, while the secondary network in the polymer matrix bridged the primary network to increase the network density. The enhancement efficiency in the thermally conductive performance of the composites reached the highest value of 59.70% at a primary-secondary network ratio of 3:1. Finite element analysis confirmed the synergistic enhancement effect of the primary and secondary thermally conductive networks. This study introduces an innovative approach to designing network structures for PBX composites, significantly enhancing their thermal conductivity.
基金supported by the National Natural Science Foundation of China (NSFC,Grant No.42174200)Shenzhen Science and Technology Program (grant No.RCJC20210609104422048)+1 种基金Shenzhen Key Laboratory Launching Project (No.ZDSYS20210702140800001)Guangdong Basic and Applied Basic Research Foundation(2023B1515040021)。
文摘Before solar eruptions,a short-term slow-rise phase is often observed,during which the pre-eruption structure ascends at speeds much greater than the photospheric motions but much less than those of the eruption phase.Numerical magnetohydrodynamic (MHD) simulations of the coronal evolution driven by photospheric motions up to eruptions have been used to explain the slow-rise phase,but their bottom driving speeds are much larger than realistic photospheric values.Therefore,it remains an open question how the excessively fast bottom driving impacts the slow-rise phase.Here we modeled the slow-rise phase before eruption initiated from a continuously sheared magnetic arcade.In particular,we performed a series of experiments with the bottom driving speed unprecedentedly approaching the photospheric value of around 1 km s^(-1).The simulations confirmed that the slowrise phase is an ideal MHD process,i.e.,a manifestation of the growing expansion of the sheared arcade in the process of approaching a fully open field state.The overlying field line above the core flux has a slow-rise speed modulated by the driving speed’s magnitude but is always over an order of magnitude larger than the driving speed.The core field also expands with speed much higher than the driving speed but much lower than that of the overlying field.By incrementally reducing the bottom-driving speed to realistic photospheric values,we anticipate better matches between the simulated slow-rise speeds and some observed ones.
基金the financial support provided by the Fundamental Research Funds for the Central Universities (Nos.FRF-TP-19-052A2 and FRF-BD-22-02)the National Natural Science Foundation of China (No.52001023)the Liao Ning Revitalization Talents Program (No.XLYC1907186)。
文摘This study investigated the influence of band microstructure induced by centerline segregation on carbide precipitation behavior and toughness in an 80 mm-thick 1 GPa low-carbon low-alloy steel plate.The quarter-thickness(1/4t)and half-thickness(1/2t)regions of the plate exhibited similar ductility and toughness after quenching.After tempering,the 1/4t region exhibited~50%and~25%enhancements in both the total elongation and low-temperature toughness at-40°C,respectively,without a decrease in yield strength,whereas the toughness of the 1/2t region decreased by~46%.After quenching,both the 1/4t and 1/2t regions exhibited lower bainite and lath martensite concentrations,but only the 1/2t region exhibited microstructure bands.Moreover,the tempered 1/4t region featured uniformly dispersed short rod-like M_(23)C_(6)carbides,and spherical MC precipitates with diameters of~20–100 nm and<20 nm,respectively.The uniformly dispersed nanosized M_(23)C_(6)carbides and MC precipitates contributed to the balance of high strength and high toughness.The band microstructure of the tempered 1/2t region featured a high density of large needle-like M3C carbides.The length and width of the large M3C carbides were~200–500 nm and~20–50 nm,respectively.Fractography analysis revealed that the high density of large carbides led to delamination cleavage fracture,which significantly deteriorated toughness.
基金supported by the Aeronautical Science Foundation of China(20111052010)the Jiangsu Graduates Innovation Project (CXZZ120163)+1 种基金the "333" Project of Jiangsu Provincethe Qing Lan Project of Jiangsu Province
文摘With the development of global position system（GPS）,wireless technology and location aware services,it is possible to collect a large quantity of trajectory data.In the field of data mining for moving objects,the problem of anomaly detection is a hot topic.Based on the development of anomalous trajectory detection of moving objects,this paper introduces the classical trajectory outlier detection（TRAOD） algorithm,and then proposes a density-based trajectory outlier detection（DBTOD） algorithm,which compensates the disadvantages of the TRAOD algorithm that it is unable to detect anomalous defects when the trajectory is local and dense.The results of employing the proposed algorithm to Elk1993 and Deer1995 datasets are also presented,which show the effectiveness of the algorithm.
基金supported in part by the National Natural Science Foundation of China under Grant 62001138Heilongjiang Provincial Natural Science Foundation of China under Grant LH2021F009+1 种基金China Postdoctoral Science Foundation under Grant 2020M670885Hei Long Jiang Postdoctoral Foundation under Grant LBH-Z20049。
文摘Orthogonal time frequency space(OTFS),as a novel 2-D modulation technique,has been proposed to achieve better BER performances over delayDoppler channels.In this paper,we propose two different power allocation(PA)algorithms in OTFS systems with zero forcing(ZF)or minimum mean square error(MMSE)equalization,where general formulas with PA are derived in advance under the condition of minimum BER(MBER)criterion.On one hand,a suboptimal MBER power allocation method is put forward to achieve better BER performances,and then analytical BER expressions are derived with proposed PA strategy.Considering the case of MMSE equalization,a combined subsymbol allocation(SA)and PA strategy is raised,where some subsymbols may be abandoned due to worse channel conditions,and then it is proven effectively to improve BER performances through theoretical and simulation results.Furthermore,BER performances with proposed joint SA and PA strategy are also investigated in delay-Doppler channels,where an improved message passing(MP)receiver based on equivalent channel matrix with PA is given.
文摘从省份尺度探讨土地利用动态变化及其生态系统服务价值(Ecosystem Service Value,ESV)响应对区域土地利用规划和生态建设评价极为重要。基于宁夏回族自治区2000、2010、2015、2020年4期Landsat ETM+、TM和OLI遥感影像,采用面向对象分类方法,构建区域2000—2020年土地利用数据库,利用土地利用动态度与ESV指数方法,并构建适用于本区域的单位面积ESV当量,分析了2000—2020年宁夏土地利用转型及其ESV响应过程。结果表明:草地和耕地是宁夏主要的土地利用类型,平均占比分别为44.7%和31.7%,随着生态工程的实施,区域耕地减少,林地和草地增加,而社会经济发展使得建设用地持续扩张。随着土地利用转型,2000—2020年宁夏ESV呈现增加—减小—增加的变化过程,范围为450.9亿~459.1亿元,2010年最高。草地和耕地是宁夏ESV的主要贡献地类,其中草地的ESV贡献为35.9%,明显低于其面积占比,而林地和湿地的ESV贡献高于其面积占比。吴忠市、固原市、中卫市、银川市、石嘴山市对宁夏ESV总量的多年平均贡献依次为29.9%、27.5%、20.5%、14.5%、7.6%。2000—2020年,各地市对全区ESV的贡献比例较为稳定,但由于各类土地利用在地市的分布差异较大,地市各个土地利用类型的ESV对该类总值的贡献发生变化。
