The study aims to explore the damage characteristics and protection technologies of liquid-filled structures under high-speed projectile impact.A series of penetration impact experiments were conducted by focusing on ...The study aims to explore the damage characteristics and protection technologies of liquid-filled structures under high-speed projectile impact.A series of penetration impact experiments were conducted by focusing on different air layer configurations.By using high-speed camera and dynamic measurement systems,the effects of air layers on the projectile penetration,pressure wave propagation,cavitation evolution,and structural dynamic responses were analyzed.The results showed that the rarefaction wave reflected from the air-liquid interface significantly reduced the peak and specific impulse of the initial pressure wave,thereby diminishing the impact load on the structure.Additionally,the compressibility of air layers also attenuated the cavitation extrusion load.Both front and rear plates exhibited superimposed deformation modes,i.e.,local deformation or petal fracture with global deformation.Air layers effectively mitigated global deformation.However,when the air layer was positioned on the projectile's trajectory,it split the water-entry process and velocity attenuation of the projectile into two relatively independent phases.And the secondary water entry pressure wave caused more severe local deformation and petal fractures on the rear plate.展开更多
This article presents a novel approach for predicting transition locations over airfoils,which are used to activate turbulence model in a Reynolds-averaged Navier-Stokes flow solver.This approach combines Dynamic Mode...This article presents a novel approach for predicting transition locations over airfoils,which are used to activate turbulence model in a Reynolds-averaged Navier-Stokes flow solver.This approach combines Dynamic Mode Decomposition(DMD)with e^Ncriterion.The core idea is to use a spatial DMD analysis to extract the modes of unstable perturbations from a steady flowfield and substitute the local Linear Stability Theory(LST)analysis to quantify the spatial growth of Tollmien–Schlichting(TS)waves.Transition is assumed to take place at the stream-wise location where the most amplified mode’s N-factor reaches a prescribed threshold and a turbulence model is activated thereafter.To improve robustness,the high-order version of DMD technique(known as HODMD)is employed.A theoretical derivation is conducted to interpret how a spatial highorder DMD analysis can extract the growth rate of the unsteady perturbations.The new method is validated by transition predictions of flows over a low-speed Natural-Laminar-Flow(NLF)airfoil NLF0416 at various angles of attack and a transonic NLF airfoil NPU-LSC-72613.The transition locations predicted by our HODMD/e^Nmethod agree well with experimental data and compare favorably to those obtained by some existing methods■.It is shown that the proposed method is able to predict transition locations for flows over different types of airfoils and offers the potential for application to 3D wings as well as more complex configurations.展开更多
Au Pd nanoalloys with tunable Pd concentrations have been synthesized and used as model catalysts. They have been directly imaged by high-angle annular dark-field scanning transmission electron microscopy and investig...Au Pd nanoalloys with tunable Pd concentrations have been synthesized and used as model catalysts. They have been directly imaged by high-angle annular dark-field scanning transmission electron microscopy and investigated by thorough analyses of their extended X-ray absorption fine structure, X-ray absorption near-edge structure, X-ray diffraction and X-ray photoelectron spectroscopy measurements. The bimetallic nanoparticles are embedded in a carbonaceous matrix and have almost an identical structure at the atomic level and the same electronic properties as Au Pd bulk alloys with the same compositions. The d-electron increase at surface Pd sites is determined by the Pd concentration of the alloy. Similarly, their activation entropy and catalytic activity for the hydrogenation of quinoline is related to the Pd concentration, with Au50 Pd50 the most active of the alloys investigated. An almost 11 times higher activity was achieved compared to a pure Pd catalyst. The experimentally measurable surface d charge at the Pd sites in the Au Pd was found to linearly correlate with the activation entropy and catalytic activity for the hydrogenation of quinoline. The alloy structure is stable, showing negligible metal segregation, dissolution-redeposition and aggregation during the hydrogenation process which involves strong adsorption.展开更多
Coal seam destabilization inflicts damage to equipment, causes property loss and personnel casualties,and severely threatens mining safety and efficient production. To further understand this destabilization based on ...Coal seam destabilization inflicts damage to equipment, causes property loss and personnel casualties,and severely threatens mining safety and efficient production. To further understand this destabilization based on the basic theory of Lippmann seam destabilization, a mathematical model was introduced for gas pressure distribution by considering intermediate principal stress and support resistance.Subsequently, we established a translation model suitable for the entire roadway coal seam with rocky roof and floor by applying the unified form of yield criterion in the state of plane strain. We also obtained the analytic expressions of coal seam stress distribution on both sides of the roadway and the widths of plastic and disturbance zones. Afterward, we analyzed several typical cases with different material yield criteria, obtained the plastic zone widths of the coal seam under different gas pressures, and assessed the effects of support resistance, roadway size, and coal strength on coal seam destabilization. Results showed that: the results obtained on the basis of Wilson and Mohr–Coulomb criteria are considerably conservative, and the use of Druker–Prager criteria to evaluate the rockburst-induced coal seam destabilization is safer than the use of the two other criteria; coal seam stability is correlated with gas pressure;and high-pressure gas accelerates the coal seam destabilization.展开更多
Predicting the constitutive response of granular soils is a fundamental goal in geomechanics.This paper presents a machine learning(ML)framework for the prediction of the stress-strain behaviour and shearinduced conta...Predicting the constitutive response of granular soils is a fundamental goal in geomechanics.This paper presents a machine learning(ML)framework for the prediction of the stress-strain behaviour and shearinduced contact fabric evolution of an idealised granular material subject to triaxial shearing.The MLbased framework is comprised of a set of mini-triaxial tests which provide a benchmark for the setup and validation of the discrete element method(DEM)model of the granular materials,a parametric DEM simulation programme of virtual triaxial tests which provides datasets of micro-and macro-mechanical information,as well as a multi-layer perceptron(MLP)neural network which is trained and tested using the DEM-based datasets.The ML model only requires the initial void ratio of the granular sample as the input for predicting its constitutive response.The excellent agreement between the ML model prediction and experimental test and DEM simulation results indicates that the MLebased modelling approach is capable of capturing accurately the effects of initial void ratio on the constitutive behaviour of idealised granular materials,bypassing the need to incorporate the complex micromechanics underlying the macroscopic mechanical behaviour of granular materials.Lastly,a detailed comparison between the used MLP model and long short-term memory(LSTM)model was made from the perspective of technical algorithm,prediction accuracy,and computational efficiency.展开更多
In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–...In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–1(24.2 ton·day),and Run 11–2(37.1 ton·day).The mistake is due to an incorrect application of a small energy non-linearity(known as the BLS non-linearity)in making plots,but has no impact to the final results.Figures 2 and 3 are now updated in this note.展开更多
Strawberry mottle virus(SMoV)and strawberry vein banding virus(SVBV)cause diseases on strawberry plants,but the effect of coinfection of SMoV and SVBV on the growth,development,and defense system of strawberry(Fragari...Strawberry mottle virus(SMoV)and strawberry vein banding virus(SVBV)cause diseases on strawberry plants,but the effect of coinfection of SMoV and SVBV on the growth,development,and defense system of strawberry(Fragaria×ananassa Duchesne)remains unknown.We investigated the effect of SMoV and SVBV coinfection on strawberry cultivar‘Benihope’.The results showed that stem diameter,leaf size,leaf number,relative chlorophyll content,total chlorophyll content,photosynthetic parameters,and stomatal aperture of SMoV and SVBV co-infected strawberry(VIS)plants were in a weaker level than uninfected control plants,indicating that viruses inhibited the growth and photosynthesis of strawberry plants.Furthermore,the initiation of flowering and fruiting stages of VIS plants were delayed by about three weeks compared with the controls,and the fruiting period was shortened,demonstrating that the reproduction of VIS plants was inhibited.Fruit quality was damaged in VIS plants due to a significant increase in fruit firmness and titratable acidity and decrease in total soluble solid content than control fruits.More dead cells and H_(2)O_(2) accumulated along the veins of VIS leaves,and the content of abscisic acid and catalase activity significantly increased,whereas anthocyanin content was lower than that of control plants.The results demonstrate that SVBV and SMoV coinfection inhibits the growth and development of‘Benihope’strawberry plants,and the plants respond to viruses by regulating stomatal aperture,the accumulation of ABA and antioxidants.To our knowledge,this study contributes information to understand how both viruses impair the strawberry growth and development for the first time.展开更多
Strawberry mottle virus(SMoV)is one of the most common viruses infecting strawberries,causing losses to fruit yield and quality.In this study,165 strawberry leaf samples were collected from six provinces of China,46 o...Strawberry mottle virus(SMoV)is one of the most common viruses infecting strawberries,causing losses to fruit yield and quality.In this study,165 strawberry leaf samples were collected from six provinces of China,46 of which tested positive for SMoV.The complete genome sequences of 11 SMoV isolates were obtained from Liaoning(DGHY3,DGHY16-2,DGHY17,DGHY20-2,DGHY21,DGHY26-2),Shandong(SDHY1,SDHY5,SDHY31-2,SDHY33-2),and Beijing(BJMX7).The RNA1 and RNA2 nucleotide identities between the 11 Chinese isolates were 95.4-99.3%and 96.3-99.6%,respectively,and they shared 78.4-96.6%and 84.8-93.5%identities with the available SMoV isolates in GenBank.Recombination analysis revealed that Chinese isolate SDHY33-2 and Canadian isolates Ontario and Simcoe were recombinants,and recombination events frequently occurred in the 3’UTR of SMoV.Phylogenetic analysis showed that in an RNA1 tree,most Chinese isolates clustered into the same group while isolate DGHY17 clustered into another group together with Czech isolate C and three Canadian isolates.In an RNA2 tree,all Chinese isolates clustered into a single group.The phylogenetic analysis based on nucleotide sequences was consistent with the results based on coat protein(CP)and RNA-dependent RNA polymerase(RdRp).Further evolutionary analysis indicated that negative selection drives SMoV evolution,and gene flow plays a major role in genetic differentiation.Additionally,reassortment and recombination also influence the evolution of SMoV.To our knowledge,this is the first report of the complete genome of SMoV isolates from China and a detailed analysis of the SMoV population structure.展开更多
The vacancy defect exhibits a remarkable improvement in the dehydriding property of MgH_(2)@Ni-CNTs.However,the corresponding mechanism is still not fully understood.Herein,the impact of vacancy defects on the dehydro...The vacancy defect exhibits a remarkable improvement in the dehydriding property of MgH_(2)@Ni-CNTs.However,the corresponding mechanism is still not fully understood.Herein,the impact of vacancy defects on the dehydrogenation properties of MgH_(2)@Ni-CNTs was studied by DFT simulation,and the corresponding models were constructed based on MS.The dehydrogenation process of MgH_(2)can be regarded as the dissociation of Mg-H and desorption of H_(2)from the MgH_(2)surface.In view of the whole dehydrogenation,the dissociation of H^(−)is the rate-determining step,which is the main reason for restricting the dehydrogenation kinetics.Compared with vacancy vacancy-defective MgH_(2)(001)surface,the appearance of vacancy defects on the(110)surface substantially reduces the energy barrier required for H dissociation to 0.070 Ha.The reason is that vacancy defects accelerate the transition of electrons from the H^(−)s orbit to the Mg^(2+)3s orbit,resulting in a decrement of the Mg-H bond strength,which makes H atoms more easily dissociated from the MgH_(2)(110)surface.Therefore,the existence of vacancy defects improves the dehydriding kinetic of MgH_(2).Most importantly,this research offers crucial directions for developing hydrogen storage materials as well as a potential fix for the slow dehydrogenation kinetics of nano-confined MgH_(2).展开更多
A variety of plants were colchicine treated to double their chromosome number.Chromosomes are genetic carriers that determine the individual traits of organisms.The doubling of chromosomes will lead to modifications i...A variety of plants were colchicine treated to double their chromosome number.Chromosomes are genetic carriers that determine the individual traits of organisms.The doubling of chromosomes will lead to modifications in plant morphology,physiology and genetics.To determine the response of mulberry trees induced by colchicine,using mulberry variety Yu-711 leaves as research materials,two small RNA libraries(control and experimental groups)were constructed.It was found that 45 known miRNA genes and 78 predicted novel miRNA genes in the sequence results.A comparison of data between the control group and the experimental group revealed 37 differentially expressed miRNA genes,19 genes of which were up-regulated and 18 genes of which were down-regulated.Eight miRNAs were selected from 37 differentially expressed miRNA genes.These miRNAs were verified by quantitative real-time PCR,and the expression levels of these miRNAs were found to be consistent with those obtained by sequencing,which proved the accuracy of sequencing results.The PsRNATarget software was used to predict the target genes of 8 miRNAs.The Gene Ontology and Kyoto Encycopedia of Genes and Genomes analysis were used to collect the functions of target genes and confirm that target genes are mainly involved in biological processes,cell components and molecular functions.novel-77 miRNA was selected from 37 differentially expressed miRNAs.What will serve as a fundamental data in understanding mulberry miRNAs function in molecular biology research and further provides the molecular mechanism of mulberry gene regulation as induced by colchicine is that the prediction of novel_77 precursor sequence and the target gene(XM_010104258.2),as well as the secondary structure analysis.展开更多
Surface acoustic wave(SAW)is a powerful technique for investigating quantum phases appearing in twodimensional electron systems.The electrons respond to the piezoelectric field of SAW through screening,attenuating its...Surface acoustic wave(SAW)is a powerful technique for investigating quantum phases appearing in twodimensional electron systems.The electrons respond to the piezoelectric field of SAW through screening,attenuating its amplitude,and shifting its velocity,which is described by the relaxation model.In this work,we systematically study this interaction using orders of magnitude lower SAW amplitude than those in previous studies.At high magnetic fields,when electrons form highly correlated states such as the quantum Hall effect,we observe an anomalously large attenuation of SAW,while the acoustic speed remains considerably high,inconsistent with the conventional relaxation model.This anomaly exists only when the SAW power is sufficiently low.展开更多
HMA2(heavy metal ATPase 2)plays a crucial role in extracellular and intracellular Zn^(2+)transport across biomembranes,maintaining ion homeostasis,and playing an important role in the normal physiological metabolism,g...HMA2(heavy metal ATPase 2)plays a crucial role in extracellular and intracellular Zn^(2+)transport across biomembranes,maintaining ion homeostasis,and playing an important role in the normal physiological metabolism,growth,and development of plants.In our study,a novel HMA2 gene,named MaHMA2,was isolated and cloned from white mulberry(Morus alba L.).The gene sequence obtained was 1,342 bp long,with an open reading frame of 1,194 bp,encoding a protein of 397 amino acids,with a predicted molecular mass of 42.852 kD and an isoelectric point of 7.53.This protein belonged to the PIB-type ATPase transport protein family.We analyzed the expression of the MaHMA2 gene by quantitative real-time PCR.The results showed that the level of MaHMA2 gene expression decreased to a Zn concentration of 800 mg/kg.Malondialdehyde and proline levels increased and responded to increasing Zn when the MaHMA2 gene was silenced,whereas the activities of peroxidase and superoxide dismutase tended to increase in response to increasing Zn^(2+)ion stress concentrations but were lower in the gene-silenced plants.These findings suggested that the MaHMA2 gene played an active role in the tolerance response of mulberry to Zn stress.展开更多
The drying of liquid droplets is a common phenomenon in daily life,and has long attracted special interest in scientific research.We propose a simple model to quantify the shape evolution of drying droplets.The model ...The drying of liquid droplets is a common phenomenon in daily life,and has long attracted special interest in scientific research.We propose a simple model to quantify the shape evolution of drying droplets.The model takes into account the friction constant between the contact line(CL)and the substrate,the capillary forces,and the evaporation rate.Two typical evaporation processes observed in experiments,i.e.,the constant contact radius(CCR)and the constant contact angle(CCA),are demonstrated by the model.Moreover,the simple model shows complicated evaporation dynamics,for example,the CL first spreads and then recedes during evaporation.Analytical models of no evaporation,CCR,and CCA cases are given,respectively.The scaling law of the CL or the contact angle as a function of time obtained by analytical model is consistent with the full numerical model,and they are all subjected to experimental tests.The general model facilitates a quantitative understanding of the physical mechanism underlying the drying of liquid droplets.展开更多
Electron systems in low dimensions are enriched with many superior properties for both fundamental research and technical developments. Wide tunability of electron density, high mobility of motion, and feasible contro...Electron systems in low dimensions are enriched with many superior properties for both fundamental research and technical developments. Wide tunability of electron density, high mobility of motion, and feasible controllability in microscales are the most prominent advantages that researchers strive for. Nevertheless, it is always difficult to fulfill all in one solid-state system. Two-dimensional electron systems(2DESs) floating above the superfluid helium surfaces are thought to meet these three requirements simultaneously, ensured by the atomic smoothness of surfaces and the electric neutrality of helium. Here we report our recent work in preparing, characterizing, and manipulating 2DESs on superfluid helium. We realized a tunability of electron density over one order of magnitude and tuned their transport properties by varying electron distribution and measurement frequency. The work we engage in is crucial for advancing research in many-body physics and for development of single-electron quantum devices rooted in these electron systems.展开更多
We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total ex...We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total exposure of 100.7 ton·day with liquid xenon.With robust estimates of the dominant background spectra,we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment.It is found that the axionelectron coupling gAe<4.6×10^(-12) for an axion mass less than 0.1 keV/c^(2) and the neutrino magnetic moment μv<4.9×10^(-11)μB at 90%confidence level.The observed excess from XENON1 T is within our experimental constraints.展开更多
We propose a major upgrade to the existing PandaX-4T experiment at the China Jinping Underground Laboratory.The new experiment,PandaX-xT,will be a multi-ten-tonne liquid xenon,ultra-low background,and general-purpose ...We propose a major upgrade to the existing PandaX-4T experiment at the China Jinping Underground Laboratory.The new experiment,PandaX-xT,will be a multi-ten-tonne liquid xenon,ultra-low background,and general-purpose observatory.The full-scaled PandaX-xT contains a 43-t liquid xenon active target.Such an experiment will significantly advance our fundamental understanding of particle physics and astrophysics.The sensitivity of dark matter direct detection will be improved by nearly two orders of magnitude compared to the current best limits,approaching the so-called“neutrino floor”for a dark matter mass above 10 GeV/c^(2),providing a key test to the Weakly Interacting Massive Particle paradigm.By searching for the neutrinoless double beta decay of^(136)Xe isotope in the detector,the effective Majorana neutrino mass can be measured to a 10-41 meV/c^(2) sensitivity,providing a key test to the Dirac/Majorana nature of neutrinos.Astrophysical neutrinos and other ultra-rare interactions can also be measured and searched for with an unprecedented background level,opening up new windows of discovery.Depending on the findings,PandaX-xT will seek the next stage upgrade utilizing isotopic separation of natural xenon.展开更多
The Panda X-4T experiment, a 4-ton scale dark matter direct detection experiment, is being planned at the China Jinping Underground Laboratory. In this paper we present a simulation study of the expected background in...The Panda X-4T experiment, a 4-ton scale dark matter direct detection experiment, is being planned at the China Jinping Underground Laboratory. In this paper we present a simulation study of the expected background in this experiment. In a 2.8-ton fiducial mass and the signal region between 1-10 keV electron equivalent energy, the total electron recoil background is found to be 4.9 × 10^(-5) kg^(-1) d^(-1) keV^(-1). The nuclear recoil background in the same region is 2.8 × 10^(-7) kg^(-1) d^(-1) keV^(-1). With an exposure of 5.6 ton-years, the sensitivity of Panda X-4 T could reach a minimum spin-independent dark matter-nucleon cross section of 6 × 10^(-48) cm^2 at a dark matter mass of 40 Ge V/c^2.展开更多
Apoptosis and autophagy are distinct cellular processes that can be highly interconnected. The cross talk between the two processes is indispensable in determining the overall cell fate. Although the apoptosis-promoti...Apoptosis and autophagy are distinct cellular processes that can be highly interconnected. The cross talk between the two processes is indispensable in determining the overall cell fate. Although the apoptosis-promoting effect of caspases has been demonstrated, the roles of autophagy-related proteins and even autophagy itself in regulating apoptosis remain poorly understood. In our present study, we found that downregulation of ubiquitin E3 ligase ASB3 led to enhanced mitochondrial apoptosis as well as autophagy, which synergistically promoted cell death in hepatocellular carcinoma(HCC). We observed the activation of caspase-8 and decrease of autophagy protein Beclin1 in apoptotic cells that were depleted of ASB3. Beclin1 was mainly cleaved by activated caspase-8 and active Beclin1 initiated mitochondrial apoptosis via locating its C-terminal fragment to mitochondria. In addition, knocking down of Beclin1 markedly blocked the apoptosis, indicating its essential role in the process.Notably, our study indicated that enhanced autophagy level might be involved in the activation of caspase-8 and promote the apoptosis. Taken together, our results demonstrated that ASB3 can regulate mitochondrial pathway of apoptosis by controlling caspase-8 mediated cleavage of Beclin1 in HCC. Therefore, ASB3 may potentially serve as a novel target for HCC therapy,especially when combined with autophagy agonist.展开更多
We report the Neutrino-less Double Beta Decay（NLDBD） search results from PandaX-Ⅱ dual-phase liquid xenon time projection chamber.The total live time used in this analysis is 403.1 days from June 2016 to August2018...We report the Neutrino-less Double Beta Decay（NLDBD） search results from PandaX-Ⅱ dual-phase liquid xenon time projection chamber.The total live time used in this analysis is 403.1 days from June 2016 to August2018.With NLDBD-optimized event selection criteria,we obtain a fiducial mass of 219 kg of natural xenon.The accumulated xenon exposure is 242 kg yr,or equivalently 22.2 kg yr of 136Xe exposure.At the region around 136Xe decay Q-value of 2458 keV,the energy resolution of PandaX-Ⅱ is 4.2%.We find no evidence of NLDBD in PandaX-Ⅱand establish a lower limit for decay half-life of 2.1×1023yr at the 90% confidence level,which corresponds to an effective Majorana neutrino mass mββ <（1.4-3.7） eV.This is the first NLDBD result reported from a dual-phase xenon experiment.展开更多
基金the financial support provided by National Natural Science Foundation of China(Grant Nos.52271338,52371342 and 51979277).
文摘The study aims to explore the damage characteristics and protection technologies of liquid-filled structures under high-speed projectile impact.A series of penetration impact experiments were conducted by focusing on different air layer configurations.By using high-speed camera and dynamic measurement systems,the effects of air layers on the projectile penetration,pressure wave propagation,cavitation evolution,and structural dynamic responses were analyzed.The results showed that the rarefaction wave reflected from the air-liquid interface significantly reduced the peak and specific impulse of the initial pressure wave,thereby diminishing the impact load on the structure.Additionally,the compressibility of air layers also attenuated the cavitation extrusion load.Both front and rear plates exhibited superimposed deformation modes,i.e.,local deformation or petal fracture with global deformation.Air layers effectively mitigated global deformation.However,when the air layer was positioned on the projectile's trajectory,it split the water-entry process and velocity attenuation of the projectile into two relatively independent phases.And the secondary water entry pressure wave caused more severe local deformation and petal fractures on the rear plate.
基金supported by the National Natural Science Foundation of China (No. 11772261)the Aeronautical Science Foundation of China (No. 2016ZA53011)+1 种基金the ATCFD Project (No. 2015-F-016)the 111 Project of China (No. B17037)
文摘This article presents a novel approach for predicting transition locations over airfoils,which are used to activate turbulence model in a Reynolds-averaged Navier-Stokes flow solver.This approach combines Dynamic Mode Decomposition(DMD)with e^Ncriterion.The core idea is to use a spatial DMD analysis to extract the modes of unstable perturbations from a steady flowfield and substitute the local Linear Stability Theory(LST)analysis to quantify the spatial growth of Tollmien–Schlichting(TS)waves.Transition is assumed to take place at the stream-wise location where the most amplified mode’s N-factor reaches a prescribed threshold and a turbulence model is activated thereafter.To improve robustness,the high-order version of DMD technique(known as HODMD)is employed.A theoretical derivation is conducted to interpret how a spatial highorder DMD analysis can extract the growth rate of the unsteady perturbations.The new method is validated by transition predictions of flows over a low-speed Natural-Laminar-Flow(NLF)airfoil NLF0416 at various angles of attack and a transonic NLF airfoil NPU-LSC-72613.The transition locations predicted by our HODMD/e^Nmethod agree well with experimental data and compare favorably to those obtained by some existing methods■.It is shown that the proposed method is able to predict transition locations for flows over different types of airfoils and offers the potential for application to 3D wings as well as more complex configurations.
文摘Au Pd nanoalloys with tunable Pd concentrations have been synthesized and used as model catalysts. They have been directly imaged by high-angle annular dark-field scanning transmission electron microscopy and investigated by thorough analyses of their extended X-ray absorption fine structure, X-ray absorption near-edge structure, X-ray diffraction and X-ray photoelectron spectroscopy measurements. The bimetallic nanoparticles are embedded in a carbonaceous matrix and have almost an identical structure at the atomic level and the same electronic properties as Au Pd bulk alloys with the same compositions. The d-electron increase at surface Pd sites is determined by the Pd concentration of the alloy. Similarly, their activation entropy and catalytic activity for the hydrogenation of quinoline is related to the Pd concentration, with Au50 Pd50 the most active of the alloys investigated. An almost 11 times higher activity was achieved compared to a pure Pd catalyst. The experimentally measurable surface d charge at the Pd sites in the Au Pd was found to linearly correlate with the activation entropy and catalytic activity for the hydrogenation of quinoline. The alloy structure is stable, showing negligible metal segregation, dissolution-redeposition and aggregation during the hydrogenation process which involves strong adsorption.
基金support of National Natural Science Foundation of China (Nos. 51674158 and 51604168)the Natural Science Foundation of Shandong Provincial (No. ZR2016EEQ18)+2 种基金and the Source Innovation Program (Applied Research Special-Youth Special) of Qingdao (No. 17-1-138-jch)Shandong University of Science and Technology ResearchFund (No. 2015JQJH105)the Taishan Scholar Talent Team Support Plan for Advantaged & Unique Discipline Areas
文摘Coal seam destabilization inflicts damage to equipment, causes property loss and personnel casualties,and severely threatens mining safety and efficient production. To further understand this destabilization based on the basic theory of Lippmann seam destabilization, a mathematical model was introduced for gas pressure distribution by considering intermediate principal stress and support resistance.Subsequently, we established a translation model suitable for the entire roadway coal seam with rocky roof and floor by applying the unified form of yield criterion in the state of plane strain. We also obtained the analytic expressions of coal seam stress distribution on both sides of the roadway and the widths of plastic and disturbance zones. Afterward, we analyzed several typical cases with different material yield criteria, obtained the plastic zone widths of the coal seam under different gas pressures, and assessed the effects of support resistance, roadway size, and coal strength on coal seam destabilization. Results showed that: the results obtained on the basis of Wilson and Mohr–Coulomb criteria are considerably conservative, and the use of Druker–Prager criteria to evaluate the rockburst-induced coal seam destabilization is safer than the use of the two other criteria; coal seam stability is correlated with gas pressure;and high-pressure gas accelerates the coal seam destabilization.
基金This study was supported by General Research Fund from the Research Grants Council of the Hong Kong SAR(Grant Nos.CityU 11201020 and 11207321)the National Natural Science Foundation of China(Grant No.51779213)as well as Contract Research Project(Ref.No.CEDD STD-30-2030-1-12R)from the Geotechnical Engineering Office.
文摘Predicting the constitutive response of granular soils is a fundamental goal in geomechanics.This paper presents a machine learning(ML)framework for the prediction of the stress-strain behaviour and shearinduced contact fabric evolution of an idealised granular material subject to triaxial shearing.The MLbased framework is comprised of a set of mini-triaxial tests which provide a benchmark for the setup and validation of the discrete element method(DEM)model of the granular materials,a parametric DEM simulation programme of virtual triaxial tests which provides datasets of micro-and macro-mechanical information,as well as a multi-layer perceptron(MLP)neural network which is trained and tested using the DEM-based datasets.The ML model only requires the initial void ratio of the granular sample as the input for predicting its constitutive response.The excellent agreement between the ML model prediction and experimental test and DEM simulation results indicates that the MLebased modelling approach is capable of capturing accurately the effects of initial void ratio on the constitutive behaviour of idealised granular materials,bypassing the need to incorporate the complex micromechanics underlying the macroscopic mechanical behaviour of granular materials.Lastly,a detailed comparison between the used MLP model and long short-term memory(LSTM)model was made from the perspective of technical algorithm,prediction accuracy,and computational efficiency.
文摘In our published letter,[1]we have identified a minor error in Figs.2 and 3.Instead,we have 2111 events in these two plots with 646,249,382,and 834 events in Run 9(20.0 ton·day),Run 10(19.4 ton·day),Run 11–1(24.2 ton·day),and Run 11–2(37.1 ton·day).The mistake is due to an incorrect application of a small energy non-linearity(known as the BLS non-linearity)in making plots,but has no impact to the final results.Figures 2 and 3 are now updated in this note.
基金This study was funded by the National Key R&D Program of China(2019YFD1001800).
文摘Strawberry mottle virus(SMoV)and strawberry vein banding virus(SVBV)cause diseases on strawberry plants,but the effect of coinfection of SMoV and SVBV on the growth,development,and defense system of strawberry(Fragaria×ananassa Duchesne)remains unknown.We investigated the effect of SMoV and SVBV coinfection on strawberry cultivar‘Benihope’.The results showed that stem diameter,leaf size,leaf number,relative chlorophyll content,total chlorophyll content,photosynthetic parameters,and stomatal aperture of SMoV and SVBV co-infected strawberry(VIS)plants were in a weaker level than uninfected control plants,indicating that viruses inhibited the growth and photosynthesis of strawberry plants.Furthermore,the initiation of flowering and fruiting stages of VIS plants were delayed by about three weeks compared with the controls,and the fruiting period was shortened,demonstrating that the reproduction of VIS plants was inhibited.Fruit quality was damaged in VIS plants due to a significant increase in fruit firmness and titratable acidity and decrease in total soluble solid content than control fruits.More dead cells and H_(2)O_(2) accumulated along the veins of VIS leaves,and the content of abscisic acid and catalase activity significantly increased,whereas anthocyanin content was lower than that of control plants.The results demonstrate that SVBV and SMoV coinfection inhibits the growth and development of‘Benihope’strawberry plants,and the plants respond to viruses by regulating stomatal aperture,the accumulation of ABA and antioxidants.To our knowledge,this study contributes information to understand how both viruses impair the strawberry growth and development for the first time.
基金funded by the National Key R&D Program of China(2019YFD1001800).
文摘Strawberry mottle virus(SMoV)is one of the most common viruses infecting strawberries,causing losses to fruit yield and quality.In this study,165 strawberry leaf samples were collected from six provinces of China,46 of which tested positive for SMoV.The complete genome sequences of 11 SMoV isolates were obtained from Liaoning(DGHY3,DGHY16-2,DGHY17,DGHY20-2,DGHY21,DGHY26-2),Shandong(SDHY1,SDHY5,SDHY31-2,SDHY33-2),and Beijing(BJMX7).The RNA1 and RNA2 nucleotide identities between the 11 Chinese isolates were 95.4-99.3%and 96.3-99.6%,respectively,and they shared 78.4-96.6%and 84.8-93.5%identities with the available SMoV isolates in GenBank.Recombination analysis revealed that Chinese isolate SDHY33-2 and Canadian isolates Ontario and Simcoe were recombinants,and recombination events frequently occurred in the 3’UTR of SMoV.Phylogenetic analysis showed that in an RNA1 tree,most Chinese isolates clustered into the same group while isolate DGHY17 clustered into another group together with Czech isolate C and three Canadian isolates.In an RNA2 tree,all Chinese isolates clustered into a single group.The phylogenetic analysis based on nucleotide sequences was consistent with the results based on coat protein(CP)and RNA-dependent RNA polymerase(RdRp).Further evolutionary analysis indicated that negative selection drives SMoV evolution,and gene flow plays a major role in genetic differentiation.Additionally,reassortment and recombination also influence the evolution of SMoV.To our knowledge,this is the first report of the complete genome of SMoV isolates from China and a detailed analysis of the SMoV population structure.
基金financed by the National Key Research and Development Program of China(Grant No.2021YFB3802400)the National Natural Science Foundation of China(Grants Nos.52071141,52271212,52201250,and 51771056)+1 种基金the Natural Science Foundation of Hebei Province(Grant No.E2018502054)the Fundamental Research Funds for the Central Universities(Grant No.2023MS148).
文摘The vacancy defect exhibits a remarkable improvement in the dehydriding property of MgH_(2)@Ni-CNTs.However,the corresponding mechanism is still not fully understood.Herein,the impact of vacancy defects on the dehydrogenation properties of MgH_(2)@Ni-CNTs was studied by DFT simulation,and the corresponding models were constructed based on MS.The dehydrogenation process of MgH_(2)can be regarded as the dissociation of Mg-H and desorption of H_(2)from the MgH_(2)surface.In view of the whole dehydrogenation,the dissociation of H^(−)is the rate-determining step,which is the main reason for restricting the dehydrogenation kinetics.Compared with vacancy vacancy-defective MgH_(2)(001)surface,the appearance of vacancy defects on the(110)surface substantially reduces the energy barrier required for H dissociation to 0.070 Ha.The reason is that vacancy defects accelerate the transition of electrons from the H^(−)s orbit to the Mg^(2+)3s orbit,resulting in a decrement of the Mg-H bond strength,which makes H atoms more easily dissociated from the MgH_(2)(110)surface.Therefore,the existence of vacancy defects improves the dehydriding kinetic of MgH_(2).Most importantly,this research offers crucial directions for developing hydrogen storage materials as well as a potential fix for the slow dehydrogenation kinetics of nano-confined MgH_(2).
基金This work was supported by China Agriculture Research System of MOF and MARA,National Key R&D Program of China,Key Projects of International Scientific and Technological Innovation Cooperation(2021YFE0111100)Guangxi Innovation-Driven Development Project(AA19182012-2)Zhenjiang Science and Technology Support Project(GJ2021015).
文摘A variety of plants were colchicine treated to double their chromosome number.Chromosomes are genetic carriers that determine the individual traits of organisms.The doubling of chromosomes will lead to modifications in plant morphology,physiology and genetics.To determine the response of mulberry trees induced by colchicine,using mulberry variety Yu-711 leaves as research materials,two small RNA libraries(control and experimental groups)were constructed.It was found that 45 known miRNA genes and 78 predicted novel miRNA genes in the sequence results.A comparison of data between the control group and the experimental group revealed 37 differentially expressed miRNA genes,19 genes of which were up-regulated and 18 genes of which were down-regulated.Eight miRNAs were selected from 37 differentially expressed miRNA genes.These miRNAs were verified by quantitative real-time PCR,and the expression levels of these miRNAs were found to be consistent with those obtained by sequencing,which proved the accuracy of sequencing results.The PsRNATarget software was used to predict the target genes of 8 miRNAs.The Gene Ontology and Kyoto Encycopedia of Genes and Genomes analysis were used to collect the functions of target genes and confirm that target genes are mainly involved in biological processes,cell components and molecular functions.novel-77 miRNA was selected from 37 differentially expressed miRNAs.What will serve as a fundamental data in understanding mulberry miRNAs function in molecular biology research and further provides the molecular mechanism of mulberry gene regulation as induced by colchicine is that the prediction of novel_77 precursor sequence and the target gene(XM_010104258.2),as well as the secondary structure analysis.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1401900 and 2019YFA0308403)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB33030000)+1 种基金the National Natural Science Foundation of China(Grant Nos.92065104,12074010,and 12141001)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302602)for sample fabrication and measurement。
文摘Surface acoustic wave(SAW)is a powerful technique for investigating quantum phases appearing in twodimensional electron systems.The electrons respond to the piezoelectric field of SAW through screening,attenuating its amplitude,and shifting its velocity,which is described by the relaxation model.In this work,we systematically study this interaction using orders of magnitude lower SAW amplitude than those in previous studies.At high magnetic fields,when electrons form highly correlated states such as the quantum Hall effect,we observe an anomalously large attenuation of SAW,while the acoustic speed remains considerably high,inconsistent with the conventional relaxation model.This anomaly exists only when the SAW power is sufficiently low.
基金This work was supported by the China Agriculture Research System of MOF and MARA,National Key R&D Program of China,the key projects of International Scientific and Technological Innovation Cooperation(Grant No.2021YFE0111100)the Guangxi Innovation-Driven Development Project(Grant No.AA19182012-2)the Zhenjiang Science and Technology Support Project(Grant No.GJ2021015).
文摘HMA2(heavy metal ATPase 2)plays a crucial role in extracellular and intracellular Zn^(2+)transport across biomembranes,maintaining ion homeostasis,and playing an important role in the normal physiological metabolism,growth,and development of plants.In our study,a novel HMA2 gene,named MaHMA2,was isolated and cloned from white mulberry(Morus alba L.).The gene sequence obtained was 1,342 bp long,with an open reading frame of 1,194 bp,encoding a protein of 397 amino acids,with a predicted molecular mass of 42.852 kD and an isoelectric point of 7.53.This protein belonged to the PIB-type ATPase transport protein family.We analyzed the expression of the MaHMA2 gene by quantitative real-time PCR.The results showed that the level of MaHMA2 gene expression decreased to a Zn concentration of 800 mg/kg.Malondialdehyde and proline levels increased and responded to increasing Zn when the MaHMA2 gene was silenced,whereas the activities of peroxidase and superoxide dismutase tended to increase in response to increasing Zn^(2+)ion stress concentrations but were lower in the gene-silenced plants.These findings suggested that the MaHMA2 gene played an active role in the tolerance response of mulberry to Zn stress.
基金Project supported by the National Natural Science Foundation of China(Grant No.21822302)the joint NSFC-ISF Research Program,China(Grant No.21961142020)+1 种基金the Fundamental Research Funds for the Central Universities,Chinathe National College Students'Innovative and Entrepreneurial Training Plan Program,China(Grant No.201910006142).
文摘The drying of liquid droplets is a common phenomenon in daily life,and has long attracted special interest in scientific research.We propose a simple model to quantify the shape evolution of drying droplets.The model takes into account the friction constant between the contact line(CL)and the substrate,the capillary forces,and the evaporation rate.Two typical evaporation processes observed in experiments,i.e.,the constant contact radius(CCR)and the constant contact angle(CCA),are demonstrated by the model.Moreover,the simple model shows complicated evaporation dynamics,for example,the CL first spreads and then recedes during evaporation.Analytical models of no evaporation,CCR,and CCA cases are given,respectively.The scaling law of the CL or the contact angle as a function of time obtained by analytical model is consistent with the full numerical model,and they are all subjected to experimental tests.The general model facilitates a quantitative understanding of the physical mechanism underlying the drying of liquid droplets.
基金supported by the Beijing Natural Science Foundation (Grant No. JQ21002)the National Natural Science Foundation of China (Grant No. T2325026)+2 种基金the National Key R&D Program of China(Grant No. 2021YFA1401902)the Key Research Program of Frontier Sciences,CAS (Grant No. ZDBS-LY-SLH0010)the CAS Project for Young Scientists in Basic Research (Grant No. YSBR-047)。
文摘Electron systems in low dimensions are enriched with many superior properties for both fundamental research and technical developments. Wide tunability of electron density, high mobility of motion, and feasible controllability in microscales are the most prominent advantages that researchers strive for. Nevertheless, it is always difficult to fulfill all in one solid-state system. Two-dimensional electron systems(2DESs) floating above the superfluid helium surfaces are thought to meet these three requirements simultaneously, ensured by the atomic smoothness of surfaces and the electric neutrality of helium. Here we report our recent work in preparing, characterizing, and manipulating 2DESs on superfluid helium. We realized a tunability of electron density over one order of magnitude and tuned their transport properties by varying electron distribution and measurement frequency. The work we engage in is crucial for advancing research in many-body physics and for development of single-electron quantum devices rooted in these electron systems.
基金Supported in part by the National Key R&D Program of China(Grant No.2016YFA0400301)the National Natural Science Foundation of China(Grant Nos.11525522,11775141,and 11755001)+5 种基金the Double First Class Plan of the Shanghai Jiao Tong University,the China Postdoctoral Science Foundation(Grant No.2018M640036)the Office of Science and Technology,Shanghai Municipal Government(Grant Nos.11DZ2260700,16DZ2260200,and 18JC1410200)the Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Education,for important supportsponsorship from the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)the Hongwen Foundation in Hong Kongthe Tencent Foundation in China。
文摘We report a search for new physics signals using the low energy electron recoil events in the complete data set from PandaX-Ⅱ,in light of the recent event excess reported by XENON1 T.The data correspond to a total exposure of 100.7 ton·day with liquid xenon.With robust estimates of the dominant background spectra,we perform sensitive searches on solar axions and neutrinos with enhanced magnetic moment.It is found that the axionelectron coupling gAe<4.6×10^(-12) for an axion mass less than 0.1 keV/c^(2) and the neutrino magnetic moment μv<4.9×10^(-11)μB at 90%confidence level.The observed excess from XENON1 T is within our experimental constraints.
基金supported by the Office of Science and Technology,Shanghai Municipal Government(Grant Nos.23JC1410200,and 22JCJC1410200)the Ministry of Science and Technology of China(Grant No.2023YFA1606200)+6 种基金the National Natural Science Foundation of China(Grant Nos.1209060,12005131,11905128,11925502,12222505,and 12175139)support from Double First Class Plan of the Shanghai Jiao Tong Universitythe Tsung-Dao Lee Institute Experimental Platform Development Fundthe sponsorship from the Hongwen Foundation in Hong KongTencentNew Cornerstone Science Foundation in ChinaYangyang Development Fund。
文摘We propose a major upgrade to the existing PandaX-4T experiment at the China Jinping Underground Laboratory.The new experiment,PandaX-xT,will be a multi-ten-tonne liquid xenon,ultra-low background,and general-purpose observatory.The full-scaled PandaX-xT contains a 43-t liquid xenon active target.Such an experiment will significantly advance our fundamental understanding of particle physics and astrophysics.The sensitivity of dark matter direct detection will be improved by nearly two orders of magnitude compared to the current best limits,approaching the so-called“neutrino floor”for a dark matter mass above 10 GeV/c^(2),providing a key test to the Weakly Interacting Massive Particle paradigm.By searching for the neutrinoless double beta decay of^(136)Xe isotope in the detector,the effective Majorana neutrino mass can be measured to a 10-41 meV/c^(2) sensitivity,providing a key test to the Dirac/Majorana nature of neutrinos.Astrophysical neutrinos and other ultra-rare interactions can also be measured and searched for with an unprecedented background level,opening up new windows of discovery.Depending on the findings,PandaX-xT will seek the next stage upgrade utilizing isotopic separation of natural xenon.
基金supported by a 985-Ⅲ grant from Shanghai Jiao Tong University,the National Natural Science Foundation of China(Grant Nos.11435008,11455001,11505112,11525522,11775141,and 11755001)the Ministry of Science and Technology of China(Grant No.2016YFA0400301)+2 种基金the Office of Science and Technology,Shanghai Municipal Government(Grant Nos.11DZ2260700,and 16DZ2260200)the Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Educationsupported in part by the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)and Hongwen Foundation in Hong Kong
文摘The Panda X-4T experiment, a 4-ton scale dark matter direct detection experiment, is being planned at the China Jinping Underground Laboratory. In this paper we present a simulation study of the expected background in this experiment. In a 2.8-ton fiducial mass and the signal region between 1-10 keV electron equivalent energy, the total electron recoil background is found to be 4.9 × 10^(-5) kg^(-1) d^(-1) keV^(-1). The nuclear recoil background in the same region is 2.8 × 10^(-7) kg^(-1) d^(-1) keV^(-1). With an exposure of 5.6 ton-years, the sensitivity of Panda X-4 T could reach a minimum spin-independent dark matter-nucleon cross section of 6 × 10^(-48) cm^2 at a dark matter mass of 40 Ge V/c^2.
基金supported by the National Natural Science Foundation of China (81372652, 81772529 and 81770579)the Development Fund for Shanghai Talents (201660).
文摘Apoptosis and autophagy are distinct cellular processes that can be highly interconnected. The cross talk between the two processes is indispensable in determining the overall cell fate. Although the apoptosis-promoting effect of caspases has been demonstrated, the roles of autophagy-related proteins and even autophagy itself in regulating apoptosis remain poorly understood. In our present study, we found that downregulation of ubiquitin E3 ligase ASB3 led to enhanced mitochondrial apoptosis as well as autophagy, which synergistically promoted cell death in hepatocellular carcinoma(HCC). We observed the activation of caspase-8 and decrease of autophagy protein Beclin1 in apoptotic cells that were depleted of ASB3. Beclin1 was mainly cleaved by activated caspase-8 and active Beclin1 initiated mitochondrial apoptosis via locating its C-terminal fragment to mitochondria. In addition, knocking down of Beclin1 markedly blocked the apoptosis, indicating its essential role in the process.Notably, our study indicated that enhanced autophagy level might be involved in the activation of caspase-8 and promote the apoptosis. Taken together, our results demonstrated that ASB3 can regulate mitochondrial pathway of apoptosis by controlling caspase-8 mediated cleavage of Beclin1 in HCC. Therefore, ASB3 may potentially serve as a novel target for HCC therapy,especially when combined with autophagy agonist.
基金Supported by grants from the Ministry of Science and Technology of China(2016YFA0400301,2016YFA0400302)a Double Top-class grant from Shanghai Jiao Tong University,grants from National Science Foundation of China(11435008,11505112,11525522,11775142,11755001)+3 种基金grants from the Office of Science and Technology,Shanghai Municipal Government(11DZ2260700,16DZ2260200,18JC1410200)the support from the Key Laboratory for Particle Physics,Astrophysics and Cosmology,Ministry of Educationsupported in part by the Chinese Academy of Sciences Center for Excellence in Particle Physics(CCEPP)Hongwen Foundation in Hong Kong
文摘We report the Neutrino-less Double Beta Decay（NLDBD） search results from PandaX-Ⅱ dual-phase liquid xenon time projection chamber.The total live time used in this analysis is 403.1 days from June 2016 to August2018.With NLDBD-optimized event selection criteria,we obtain a fiducial mass of 219 kg of natural xenon.The accumulated xenon exposure is 242 kg yr,or equivalently 22.2 kg yr of 136Xe exposure.At the region around 136Xe decay Q-value of 2458 keV,the energy resolution of PandaX-Ⅱ is 4.2%.We find no evidence of NLDBD in PandaX-Ⅱand establish a lower limit for decay half-life of 2.1×1023yr at the 90% confidence level,which corresponds to an effective Majorana neutrino mass mββ <（1.4-3.7） eV.This is the first NLDBD result reported from a dual-phase xenon experiment.
