Interlayer antiferromagnetic coupling,small magnetic anisotropy,and low air stability of the intrinsic magnetic topological insulator MnBi_(2)Te_(4)have been critical bottlenecks to the future application of the quant...Interlayer antiferromagnetic coupling,small magnetic anisotropy,and low air stability of the intrinsic magnetic topological insulator MnBi_(2)Te_(4)have been critical bottlenecks to the future application of the quantum anomalous Hall efect(QAHE)at zero magnetic feld.In this study,we propose a scheme to utilize capped sliding van der Waals materials to efectively modulate the magnetic and topological properties of MnBi_(2)Te_(4).Our results demonstrate that the h-BN/MnBi_(2)Te_(4)/h-BN heterostructure,constructed by sliding ferroelectric h-BN bilayer and MnBi_(2)Te_(4),not only realizes a transition from interlayer antiferromagnetic to ferromagnetic coupling but also signifcantly enhances the out-of-plane magnetism and air stability of MnBi_(2)Te_(4).Moreover,the above magnetic properties can be further improved by tuning the interlayer distance between h-BN and MnBi_(2)Te_(4).Additionally,the obtained band structures and topological properties clearly support that the h-BN/MnBi_(2)Te_(4)/hBN heterostructure can harbor the QAHE with a Chern number of C=1.This work provides a new and nonvolatile modulation approach to achieve high-temperature and high-precision QAHE at zero magnetic feld.展开更多
Over the last decade,nuclear theory has made dramatic progress in few-body and ab initio many-body calculations.These great advances stem from chiral efective feld theory(xEFT),which provides an efcient expansion and ...Over the last decade,nuclear theory has made dramatic progress in few-body and ab initio many-body calculations.These great advances stem from chiral efective feld theory(xEFT),which provides an efcient expansion and consistent treatment of nuclear forces as inputs of modern many-body calculations,among which the in-medium similarity renormalization group(IMSRG)and its variants play a vital role.On the other hand,signifcant eforts have been made to provide a unifed description of the structure,decay,and reactions of the nuclei as open quantum systems.While a fully comprehensive and microscopic model has yet to be realized,substantial progress over recent decades has enhanced our understanding of open quantum systems around the dripline,which are often characterized by exotic structures and decay modes.To study these interesting phenomena,Gamow coupled-channel(GCC)method,in which the open quantum nature of few-body valence nucleons coupled to a deformed core,has been developed.This review focuses on the developments of the advanced IMSRG and GCC and their applications to nuclear structure and reactions.展开更多
Blast pressure measurements of a controlled underwater explosion in the sea were carried out.An explosive of 25-kg trinitro-toluene(TNT)equivalent was detonated,and the blast pressures were recorded by eight diferent ...Blast pressure measurements of a controlled underwater explosion in the sea were carried out.An explosive of 25-kg trinitro-toluene(TNT)equivalent was detonated,and the blast pressures were recorded by eight diferent high-performance pressure sensors that work at the nonresonant high-voltage output in adverse underwater conditions.Recorded peak pressure values are used to establish a relationship in the well-known form of empirical underwater explosion(UNDEX)loading formula.Constants of the formula are redetermined by employing the least-squares method in two diferent forms for best ftting to the measured data.The newly determined constants are found to be only slightly diferent from the generally accepted ones.展开更多
In recent years,the anti-tumor activity of Donglingeao(Rabdosiae Rubescentis Herba)has received much attention.The diterpenoid rubescensine A as its main anti-cancer active component has anti-tumor,anti-bacterial,anti...In recent years,the anti-tumor activity of Donglingeao(Rabdosiae Rubescentis Herba)has received much attention.The diterpenoid rubescensine A as its main anti-cancer active component has anti-tumor,anti-bacterial,anti-inflammatory pharmacological effects.At present,researches on the chemical composition,phar-macological effects and clinical application of Donglingeao(Rabdosiae Rubescentis Herba)have made impor-tant progress.The upstream key enzyme genes have basically been cloned in the biosynthesis pathway of diter-penoids.However,the synthetic route of rubescensine A is not clear,and there are few reports on the cyto-chrome P450 family that regulates the synthesis of rubescensine A.Therefore,it is necessary to further study the key enzyme genes that regulate the synthesis of rubescensine A to provide research basis for the in vitro synthesis of rubescensine A.展开更多
In this paper, the qualitative properties of general nonautonomous Lotka-Volterran-species competitive systems with impulsive e？ects are studied. Some new criteria on thepermanence, extinction and global attractivity...In this paper, the qualitative properties of general nonautonomous Lotka-Volterran-species competitive systems with impulsive e？ects are studied. Some new criteria on thepermanence, extinction and global attractivity of partial species are established by used themethods of inequalities estimate and Liapunov functions. As applications, nonautonomous twospecies Lotka-Volterra systems with impulses are discussed.展开更多
Shock-induced separation of turbulent boundary layers represents a long-studied problem in compressible flow, bearing, for example, on applications in high speed aerodynamics, rocketry, wind tunnel design, and turboma...Shock-induced separation of turbulent boundary layers represents a long-studied problem in compressible flow, bearing, for example, on applications in high speed aerodynamics, rocketry, wind tunnel design, and turbomachinery. Experimental investigations have generally sought to expose essential physics using geometrically simple configurations.展开更多
The buried depth of the gas-producing reservoir in the Kuqa foreland thrust belt of the Tarim Basin exceeds 6000 m.The average matrix porosity of the reservoir is 5.5%,and the average matrix permeability is 0.128×...The buried depth of the gas-producing reservoir in the Kuqa foreland thrust belt of the Tarim Basin exceeds 6000 m.The average matrix porosity of the reservoir is 5.5%,and the average matrix permeability is 0.128×10^(−3)μm^(2).In order to reveal the characteristics and efectiveness of ultra-deep fractures and their efects on reservoir properties and natural gas production,outcrops,cores,thin section,image logs and production testing data are used to investigate the efectiveness of tectonic fractures in ultra-deep reservoirs in the Kuqa foreland thrust zone,and the corresponding geological signifcance for oil and gas exploration and development are discussed.Tectonic fractures in the thrust belt include EW-trending high-angle tensile fractures and NS-trending vertical shear fractures.The former has a relatively high flling rate,while the latter is mostly unflled.Micro-fractures are usually grain-piercing-through cracks with width of 10-100 microns.In the planar view,the efective fractures are concentrated in the high part and wing zones of the long axis of the anticline,and along the vertical direction,they are mainly found in the tensile fracture zone above the neutral plane.The adjustment fracture zone has the strongest vertical extension abilities and high efectiveness,followed by the nearly EW longitudinal tensile fracture zone,and the netted fracture zone with multiple dip angles.The efectiveness of fracture is mainly controlled by fracture aperture and flling degrees.Efective fractures can increase reservoir permeability by 1-2 orders of magnitude.The higher part of the anticline is associated with high tectonic fracture permeability,which control enrichment and high production of natural gas.The netted vertical open fractures efectively communicate with pores and throats of the reservoir matrix,which forms an apparent-homogenous to medium-heterogeneous body that is seen with high production of natural gas sustained for a long term.展开更多
With increased cyber attacks over years,information system security assessment becomes more and more important.This paper provides an ontology-based attack model,and then utilizes it to assess the information system s...With increased cyber attacks over years,information system security assessment becomes more and more important.This paper provides an ontology-based attack model,and then utilizes it to assess the information system security from attack angle.We categorize attacks into a taxonomy suitable for security assessment.The proposed taxonomy consists of five dimensions,which include attack impact,attack vector,attack target,vulnerability and defense.Afterwards we build an ontology according to the taxonomy.In the ontology,attack related concepts included in the five dimensions and relationships between them are formalized and analyzed in detail.We also populate our attack ontology with information from national vulnerability database(NVD)about the vulnerabilities,such as common vulnerabilities and exposures(CVE),common weakness enumeration(CWE),common vulnerability scoring system(CVSS),and common platform enumeration(CPE).Finally we propose an ontology-based framework for security assessment of network and computer systems,and describe the utilization of ontology in the security assessment and the method for evaluating attack efect on the system when it is under attack.展开更多
Coal is the one of foundations of energy and economic structure in China,while the unsealing of coal mine fres would cause a great risk of coal re-ignition.In order to explore the infuence of pressure-bearing state on...Coal is the one of foundations of energy and economic structure in China,while the unsealing of coal mine fres would cause a great risk of coal re-ignition.In order to explore the infuence of pressure-bearing state on the re-ignition characteristics for residual coal,the uniaxial compression equipped with a temperature-programmed device was built.The scanning electron microscope,synchronous thermal analyzer and Fourier transform infrared absorption spectrometer was applied to investigate the microscopic structure and thermal efect of the coal samples.Moreover,the microscopic efect of uniaxial stress on coal re-ignition is revealed,and the re-ignition mechanism is also obtained.As the uniaxial stress increasing,the number,depth and length of the fractures of the pre-treated coal increases.The application of uniaxial stress causes the thermal conductivity to change periodically,enhances the inhibition of injecting nitrogen on heat transfer and prolonges the duration of oxidation exothermic.The content of oxygen-containing functional groups has a high correlation with apparent activation energy,and coal samples at 6 MPa is more probability to re-ignite while the fre zone is unsealed.Uniaxial stress could control the re-ignition mechanism by changing the structure of fractures and pores.The side chains and functional groups of coal structure are easier to be broken by thermal-stress coupling.The higher the·OH content,the more difcult coal samples would be re-ignited.The research results would lay a solid theoretical foundation for the safe unsealing of closed fre-areas underground,tighten the common bond between the actual industry and the experimental theory in closed fre-areas underground,and provide the theoretical guidance for coal re-ignition preventing.展开更多
Deep rock mass tends to be broken into blocks when mining for materials deep below the surface.The rock layer of the roof of the mine can be regarded as a system of blocks of fractured rock mass.When subjected to high...Deep rock mass tends to be broken into blocks when mining for materials deep below the surface.The rock layer of the roof of the mine can be regarded as a system of blocks of fractured rock mass.When subjected to high ground stress and mining-induced disturbance,the efect of the ultra-low friction of the block system easily becomes apparent,and can induce rock burst and other accidents.By taking the block of rock mass as research object,this study developed a test system for ultra-low friction to experimentally examine its efects on the broken blocks under stress wave-induced disturbance.We used the horizontal displacement of the working block as the characteristic parameter refecting the efect of ultra-low friction,and examine its characteristic laws of horizontal displacement,acceleration,and energy when subjected to the efects of ultra-low friction by changing the frequency and amplitude of the stress wave-induced disturbance.The results show that the frequency of stress wave-induced disturbance is related to the generation of ultra-low friction in the broken block.The frequency of disturbance of the stress wave is within 1–3 Hz,and signifcantly increases the maximum acceleration and horizontal displacement of the broken blocks.The greater the intensity of the stress wave-induced disturbance is,the higher is the degree of block fragmentation,and the more likely are efects of ultra-low friction to occur between the blocks.The greater the intensity of the horizontal impact load is,the higher is the degree of fragmentation of the rock mass,and the easier it is for the efects of ultra-low friction to occur.Stress wave-induced disturbance and horizontal impact are the main causes of sliding instability of the broken blocks.When the dominant frequency of the kinetic energy of the broken block is within 20 Hz,the efects of ultra-low friction are more likely.展开更多
The low density and high corrosion resistance of titanium alloy make it a material with various applications in the aerospace industry. However, because of its high specifc strength and poor thermal conductivity, ther...The low density and high corrosion resistance of titanium alloy make it a material with various applications in the aerospace industry. However, because of its high specifc strength and poor thermal conductivity, there are problems such as high cutting force, poor surface integrity, and high cutting temperature during conventional machining. As an advanced processing method with high efciency and low damage, laser-assisted machining can improve the machinability of titanium alloy. In this study, a picosecond pulse laser-assisted scratching (PPLAS) method considering both the temperature-dependent material properties and ultrashort pulse laser’s characteristics is frst proposed. Then, the efects of laser power, scratching depth, and scratching speed on the distribution of stress and temperature feld are investigated by simulation. Next, PPLAS experiments are conducted to verify the correctness of the simulation and reveal the removal behavior at various combinations of laser power and scratching depths. Finally, combined with simulated and experimental results, the removal mechanism under the two machining methods is illustrated. Compared with conventional scratching (CS), the tangential grinding force is reduced by more than 60% and the material removal degree is up to 0.948 during PPLAS, while the material removal is still primarily in the form of plastic removal. Grinding debris in CS takes the form of stacked fakes with a “fsh scale” surface, whereas it takes the form of broken serrations in PPLAS. This research can provide important guidance for titanium alloy grinding with high surface quality and low surface damage.展开更多
Small specimens are increasingly being used in getting mechanical properties directly when there are limited materials to facilitate standard specimens,which play a great role in the rapid measurement of mechanical pr...Small specimens are increasingly being used in getting mechanical properties directly when there are limited materials to facilitate standard specimens,which play a great role in the rapid measurement of mechanical properties and residual life assessment of in-service reactor components.Although tensile and fatigue properties of the small specimens are investigated extensively,theoretical models for describing the mechanical properties of small specimens need to be established.Here,we conduct a systematic investigation of tensile and fatigue properties of pure Cu specimens with thicknesses ranging from 3 to 0.2 mm.The results show that the decrease in uniform elongation of the 0.2 mm-thick specimens is mainly due to the efects of grain boundary and free surface on the strain hardening rate.A modifed theoretical model correlated with the ratio of the surface grain layer thickness to the grain size is proposed to predict variation in yield strength of the small specimens more accurately.Furthermore,the mechanism for the diference in fatigue life between the 0.2 mm-thick specimen and other thicker specimens is elucidated.The Basquin equation-based model is presented as a potential way to evaluate the fatigue life of metals using small specimens.展开更多
The bactericidal effect of laser radiation with a quartz fiber-based transmission system with a strong absorption coating converter against bacteria associated with urological stones has been studied.Gr am-negative ro...The bactericidal effect of laser radiation with a quartz fiber-based transmission system with a strong absorption coating converter against bacteria associated with urological stones has been studied.Gr am-negative rod Escherichia coli and the Gram-positive coccus Staphylococcus epi-dermidis,Staphylococcus aureus,Enterococcus faecalis and Enterococcus faecium were used in this study.Each bacterial species was treated by continuous-wave near infrared laser coupled with bare fiber tip or strongly absorption coating fiber tip.After treatment,the temperature of bacterial suspension was measured.In addition,the temperature dist ribution was analyzed.It has been shown that using laser with a strongly absorption coating fiber tip results in significant bactericidal effect.The decrease of the amount of E.coli and S.epidermidis was 100%after treatment with an output power of6 W of radiation at a wavelength of 0.97 pum for 40s.Number of S.aureus and Ent.facium colony-forming unit was reduced to 70%after same exposure.The peak temperature of bacterial suspension was 86℃ after treatment by laser with a strongly absorption coating fiber tip.Laser with a strongly absorpt ion coating fiber tip provides large scale hydrodynamic flows directed away from the fiber tip.The laser with a strongly absorption coating fiber tip has bactericidal effect.The main role is associated with the effect of high temperature,which,in the form of flow in a liquid medium,afects bacteria.展开更多
We observed a phenomenon that different scattering components have different decorrelation time.Based on decorrelation time difference,we proposed a method to image an object hidden behind a turbid medium in a reflect...We observed a phenomenon that different scattering components have different decorrelation time.Based on decorrelation time difference,we proposed a method to image an object hidden behind a turbid medium in a reflection mode.In order to suppress the big disturbance calused by reflection and back scattering,two framnes of speckles are recorded in sequence,and their difference is used for image reconstruction.Our method is immune to both medium motions and object movements.展开更多
The incre asing interest in RNA modifications has signifcantly advanced epigenomic and epitranscriptomic technologies.This study focuses on the immuno oncological impact of ALYREF in human cancer through a pan-cancer ...The incre asing interest in RNA modifications has signifcantly advanced epigenomic and epitranscriptomic technologies.This study focuses on the immuno oncological impact of ALYREF in human cancer through a pan-cancer analysis,enhancing understanding of this gene's role in cancer.We observed differential ALYREF expression between tumor and normal samples,correl ating strongly with prognosis in various cancers,particularly kidney renal papillary cell carcinoma(KIRP)and liver hepatocellular carcinoma(LIHC).ALYREF showed a negative correlation with most tumor-infitrating cells in lung squamous cell carcinoma(LUSC)and lymphoid neoplasm difuse large B-cell lymphoma(DLBC),while positive correlations were noted in IIHC,kidney chromophobe(KICH),mesothelioma(MESO),KIRP,pheochromocytoma and paraganglioma(PARD),and glioma(GBMLGG).Aditionally,ALYREF expression was closely associated with tumor heterogeneity,stemness indices,and a high mutation rate in TP53 across these cancers.In conclusion,ALYREF may serve as an oncogenic biomarker in numerous cancers,meriting further research attention.展开更多
Background Drug‑resistant epilepsy(DRE)exerts substantial clinical,humanistic and economic burdens on patients,their families and the healthcare system.Vagus nerve stimulation(VNS)has been extensively tested in clinic...Background Drug‑resistant epilepsy(DRE)exerts substantial clinical,humanistic and economic burdens on patients,their families and the healthcare system.Vagus nerve stimulation(VNS)has been extensively tested in clinical trial settings to decrease the frequency of seizures in patients with DRE who are not candidates for surgery;the results indicate promising efcacy and a well‑tolerated safety profle.However,real‑world evidence is still lacking.This retro‑spective study evaluated the safety and efcacy of VNS in patients with DRE.Methods The current study was a retrospective chart review of the medical records of children and adults with DRE treated with VNS between December 2006 and November 2022.The primary outcome of the present study was the percentage of patients who experienced a reduction in seizure frequency of more than 50%compared with the frequency at baseline(the period before VNS device insertion).Results A total of 103 patients were included.The percentage of patients who achieved a reduction of more than 50%in seizure frequency was 23%at six months,36%at 12 months,65%at 18 months,and 72%at 24 months.Similarly,the percentage of patients with complete resolution of interictal epileptiform discharges(IEDs)increased from 30%at six months to 60%after 24 months.The overall Quality of Life in Epilepsy(QOLIE‑31)score at the end of follow‑up was 39.46±13.68 points.Two patients(1.9%)reported experiencing side efects at the end of follow‑up.Conclusions VNS implementation led to a signifcant reduction in the seizure frequency and resolution of IEDs,with a well‑tolerated safety profle.The fndings highlight the potential role of VNS in managing DRE and warrant its consideration for treating patients with DRE.展开更多
Background Both increasing native species diversity and reducing nutrient availability can increase the ability of native plant communities to resist alien plant invasions. Furthermore, native species diversity and nu...Background Both increasing native species diversity and reducing nutrient availability can increase the ability of native plant communities to resist alien plant invasions. Furthermore, native species diversity and nutrient availabil-ity may interact to influence alien plant invasions. So far, however, little is known about the interactive effect of spe-cies diversity and nutrient availability on reproduction of alien invasive plants. We constructed native plant communi-ties with one, four or eight species under low and high nutrient supply and then let them be invaded by the invasive alien plant Bidens pilosa.Results At both high and low nutrient supply, increasing native species richness significantly increased aboveground biomass of the native plant community and decreased aboveground biomass and biomass proportion of the invader B. pilosa. Reproductive biomass of B. pilosa decreased significantly with increasing native species richness under high nutrient supply, but this effect was not observed under low nutrient supply. Net biodiversity effect on seed mass of B. pilosa decreased significantly with increasing native species diversity under high nutrient supply, but not under low nutrient supply. This was mainly because the selection effect became dominant with increasing species richness under high nutrient supply.Conclusions Our study suggest that native species richness and nutrient supply can interact to influence repro-duction of invasive alien plant species and that measures to help maintain a high level of native species richness and to reduce nutrient supply could be useful for efficient invasive plant control.展开更多
Background Previous studies have found that patients with epilepsy are more likely to sufer impulsivity.However,the causal relationship between impulsivity and epilepsy is unknown.In this study,we conduct a bidirectio...Background Previous studies have found that patients with epilepsy are more likely to sufer impulsivity.However,the causal relationship between impulsivity and epilepsy is unknown.In this study,we conduct a bidirectional Mendelian randomization(MR)study to explore the causal relationship between impulsivity and epilepsy with recurrent seizure.Methods Data of the genome-wide association studies(GWAS)on 14 impulsivity traits and epilepsy were obtained from the GWAS catalog and UK Biobank.Inverse-variance weighted(IVW)and weighted median(WM)methods were utilized for MR estimates.IVW,MR-Egger regression,and MR-pleiotropy residual sum and outlier(MR-PRESSO)methods were used to assess heterogeneity and pleiotropy.Results Single-nucleotide polymorphisms(SNPs)related to the lack of perseverance were associated with a decreased risk of epilepsy with recurrent seizures according to the results of IVW(odd ratio[OR]=0.93,95%confdent interval[CI]=0.90-0.97,P=0.001)and WM(OR=0.93,95%CI=0.87-0.98,P=0.007).Meanwhile,heterogeneity was not observed with a Cochran Q-derived P value of 0.819 for MR egger and a P value of 0.808 for IVW.Pleiotropy was not found according to the MR-PRESSO(P=0.273).The other 13 impulsivity traits had no causal efect on epilepsy with recurrent seizures.Meanwhile,SNPs related with epilepsy with recurrent seizures had no causal efect on the 14 impulsivity traits.Conclusions This MR study suggests that lack of perseverance may be a protective factor against epilepsy with recurrent seizures.However,epilepsy with recurrent seizures does not afect impulsivity.展开更多
基金supported by the National Key R&D Program of China(Grant No.2024YFA1408103)National Natural Science Foundation of China(Grants No.11974098,12474158,12234017 and 12488101)+3 种基金Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302800)Natural Science Foundation of Hebei Province(Grant No.A202305017)Anhui Initiative in Quantum Information Technologies(Grant No.AHY170000)Fundamental Research Funds for the Central Universities(Grant No.WK2340000082)。
文摘Interlayer antiferromagnetic coupling,small magnetic anisotropy,and low air stability of the intrinsic magnetic topological insulator MnBi_(2)Te_(4)have been critical bottlenecks to the future application of the quantum anomalous Hall efect(QAHE)at zero magnetic feld.In this study,we propose a scheme to utilize capped sliding van der Waals materials to efectively modulate the magnetic and topological properties of MnBi_(2)Te_(4).Our results demonstrate that the h-BN/MnBi_(2)Te_(4)/h-BN heterostructure,constructed by sliding ferroelectric h-BN bilayer and MnBi_(2)Te_(4),not only realizes a transition from interlayer antiferromagnetic to ferromagnetic coupling but also signifcantly enhances the out-of-plane magnetism and air stability of MnBi_(2)Te_(4).Moreover,the above magnetic properties can be further improved by tuning the interlayer distance between h-BN and MnBi_(2)Te_(4).Additionally,the obtained band structures and topological properties clearly support that the h-BN/MnBi_(2)Te_(4)/hBN heterostructure can harbor the QAHE with a Chern number of C=1.This work provides a new and nonvolatile modulation approach to achieve high-temperature and high-precision QAHE at zero magnetic feld.
基金National Key R&D Program of China under Grant Nos.2023YFA1606400 and 2022YFA1602303National Natural Science Foundation of China under Grants Nos.12335007,12035001,11921006,12347106,12147101,and 12205340+1 种基金Gansu Natural Science Foundation under Grant No.22JR5RA123U.S.Department of Energy(DOE),Office of Science,under SciDAC-5(NUCLEI collaboration)。
文摘Over the last decade,nuclear theory has made dramatic progress in few-body and ab initio many-body calculations.These great advances stem from chiral efective feld theory(xEFT),which provides an efcient expansion and consistent treatment of nuclear forces as inputs of modern many-body calculations,among which the in-medium similarity renormalization group(IMSRG)and its variants play a vital role.On the other hand,signifcant eforts have been made to provide a unifed description of the structure,decay,and reactions of the nuclei as open quantum systems.While a fully comprehensive and microscopic model has yet to be realized,substantial progress over recent decades has enhanced our understanding of open quantum systems around the dripline,which are often characterized by exotic structures and decay modes.To study these interesting phenomena,Gamow coupled-channel(GCC)method,in which the open quantum nature of few-body valence nucleons coupled to a deformed core,has been developed.This review focuses on the developments of the advanced IMSRG and GCC and their applications to nuclear structure and reactions.
文摘Blast pressure measurements of a controlled underwater explosion in the sea were carried out.An explosive of 25-kg trinitro-toluene(TNT)equivalent was detonated,and the blast pressures were recorded by eight diferent high-performance pressure sensors that work at the nonresonant high-voltage output in adverse underwater conditions.Recorded peak pressure values are used to establish a relationship in the well-known form of empirical underwater explosion(UNDEX)loading formula.Constants of the formula are redetermined by employing the least-squares method in two diferent forms for best ftting to the measured data.The newly determined constants are found to be only slightly diferent from the generally accepted ones.
基金We thank for the funding support from the National Natural Science Foundation of China(00108028)。
文摘In recent years,the anti-tumor activity of Donglingeao(Rabdosiae Rubescentis Herba)has received much attention.The diterpenoid rubescensine A as its main anti-cancer active component has anti-tumor,anti-bacterial,anti-inflammatory pharmacological effects.At present,researches on the chemical composition,phar-macological effects and clinical application of Donglingeao(Rabdosiae Rubescentis Herba)have made impor-tant progress.The upstream key enzyme genes have basically been cloned in the biosynthesis pathway of diter-penoids.However,the synthetic route of rubescensine A is not clear,and there are few reports on the cyto-chrome P450 family that regulates the synthesis of rubescensine A.Therefore,it is necessary to further study the key enzyme genes that regulate the synthesis of rubescensine A to provide research basis for the in vitro synthesis of rubescensine A.
基金Supported by The National Natural Science Foundation of P.R. China [60764003]The Scientific Research Programmes of Colleges in Xinjiang [XJEDU2007G01, XJEDU2006I05]+1 种基金The National Key Technologies R & D Program of China [2008BAI68B01]The Natural Science Foundation of Jiangxi Province [2008GZS0027]
文摘In this paper, the qualitative properties of general nonautonomous Lotka-Volterran-species competitive systems with impulsive e？ects are studied. Some new criteria on thepermanence, extinction and global attractivity of partial species are established by used themethods of inequalities estimate and Liapunov functions. As applications, nonautonomous twospecies Lotka-Volterra systems with impulses are discussed.
文摘Shock-induced separation of turbulent boundary layers represents a long-studied problem in compressible flow, bearing, for example, on applications in high speed aerodynamics, rocketry, wind tunnel design, and turbomachinery. Experimental investigations have generally sought to expose essential physics using geometrically simple configurations.
基金This work was supported by the National Key Research and Development Project(No.2019YFC0605501)the National Science and Technology Major Project(2016ZX05003001).
文摘The buried depth of the gas-producing reservoir in the Kuqa foreland thrust belt of the Tarim Basin exceeds 6000 m.The average matrix porosity of the reservoir is 5.5%,and the average matrix permeability is 0.128×10^(−3)μm^(2).In order to reveal the characteristics and efectiveness of ultra-deep fractures and their efects on reservoir properties and natural gas production,outcrops,cores,thin section,image logs and production testing data are used to investigate the efectiveness of tectonic fractures in ultra-deep reservoirs in the Kuqa foreland thrust zone,and the corresponding geological signifcance for oil and gas exploration and development are discussed.Tectonic fractures in the thrust belt include EW-trending high-angle tensile fractures and NS-trending vertical shear fractures.The former has a relatively high flling rate,while the latter is mostly unflled.Micro-fractures are usually grain-piercing-through cracks with width of 10-100 microns.In the planar view,the efective fractures are concentrated in the high part and wing zones of the long axis of the anticline,and along the vertical direction,they are mainly found in the tensile fracture zone above the neutral plane.The adjustment fracture zone has the strongest vertical extension abilities and high efectiveness,followed by the nearly EW longitudinal tensile fracture zone,and the netted fracture zone with multiple dip angles.The efectiveness of fracture is mainly controlled by fracture aperture and flling degrees.Efective fractures can increase reservoir permeability by 1-2 orders of magnitude.The higher part of the anticline is associated with high tectonic fracture permeability,which control enrichment and high production of natural gas.The netted vertical open fractures efectively communicate with pores and throats of the reservoir matrix,which forms an apparent-homogenous to medium-heterogeneous body that is seen with high production of natural gas sustained for a long term.
基金the National Basic Research Program(973)of China(No.2010CB731403)the Information Network Security Key Laboratory Open Project of the Ministry of Public Security of China(No.C09603)the Shanghai Key Scientific and Technological Project(No.11511504302)
文摘With increased cyber attacks over years,information system security assessment becomes more and more important.This paper provides an ontology-based attack model,and then utilizes it to assess the information system security from attack angle.We categorize attacks into a taxonomy suitable for security assessment.The proposed taxonomy consists of five dimensions,which include attack impact,attack vector,attack target,vulnerability and defense.Afterwards we build an ontology according to the taxonomy.In the ontology,attack related concepts included in the five dimensions and relationships between them are formalized and analyzed in detail.We also populate our attack ontology with information from national vulnerability database(NVD)about the vulnerabilities,such as common vulnerabilities and exposures(CVE),common weakness enumeration(CWE),common vulnerability scoring system(CVSS),and common platform enumeration(CPE).Finally we propose an ontology-based framework for security assessment of network and computer systems,and describe the utilization of ontology in the security assessment and the method for evaluating attack efect on the system when it is under attack.
基金funding provided by the National Natural Science Foundation of China(52074108 and 51874124)the Project supported by Fund for Creative Talents of Henan Colleges in China(22HASTIT012)+1 种基金the Key Science and Technology Program of Henan Province(212102310007)It also supported by the Scientifc Research Foundation of the Higher Education Institutions of Henan Province in China(22A620001).
文摘Coal is the one of foundations of energy and economic structure in China,while the unsealing of coal mine fres would cause a great risk of coal re-ignition.In order to explore the infuence of pressure-bearing state on the re-ignition characteristics for residual coal,the uniaxial compression equipped with a temperature-programmed device was built.The scanning electron microscope,synchronous thermal analyzer and Fourier transform infrared absorption spectrometer was applied to investigate the microscopic structure and thermal efect of the coal samples.Moreover,the microscopic efect of uniaxial stress on coal re-ignition is revealed,and the re-ignition mechanism is also obtained.As the uniaxial stress increasing,the number,depth and length of the fractures of the pre-treated coal increases.The application of uniaxial stress causes the thermal conductivity to change periodically,enhances the inhibition of injecting nitrogen on heat transfer and prolonges the duration of oxidation exothermic.The content of oxygen-containing functional groups has a high correlation with apparent activation energy,and coal samples at 6 MPa is more probability to re-ignite while the fre zone is unsealed.Uniaxial stress could control the re-ignition mechanism by changing the structure of fractures and pores.The side chains and functional groups of coal structure are easier to be broken by thermal-stress coupling.The higher the·OH content,the more difcult coal samples would be re-ignited.The research results would lay a solid theoretical foundation for the safe unsealing of closed fre-areas underground,tighten the common bond between the actual industry and the experimental theory in closed fre-areas underground,and provide the theoretical guidance for coal re-ignition preventing.
基金supported by the National Science Foundation of China(51974148)the Liaoning Xingliao Talent Program(XLYC1807130).
文摘Deep rock mass tends to be broken into blocks when mining for materials deep below the surface.The rock layer of the roof of the mine can be regarded as a system of blocks of fractured rock mass.When subjected to high ground stress and mining-induced disturbance,the efect of the ultra-low friction of the block system easily becomes apparent,and can induce rock burst and other accidents.By taking the block of rock mass as research object,this study developed a test system for ultra-low friction to experimentally examine its efects on the broken blocks under stress wave-induced disturbance.We used the horizontal displacement of the working block as the characteristic parameter refecting the efect of ultra-low friction,and examine its characteristic laws of horizontal displacement,acceleration,and energy when subjected to the efects of ultra-low friction by changing the frequency and amplitude of the stress wave-induced disturbance.The results show that the frequency of stress wave-induced disturbance is related to the generation of ultra-low friction in the broken block.The frequency of disturbance of the stress wave is within 1–3 Hz,and signifcantly increases the maximum acceleration and horizontal displacement of the broken blocks.The greater the intensity of the stress wave-induced disturbance is,the higher is the degree of block fragmentation,and the more likely are efects of ultra-low friction to occur between the blocks.The greater the intensity of the horizontal impact load is,the higher is the degree of fragmentation of the rock mass,and the easier it is for the efects of ultra-low friction to occur.Stress wave-induced disturbance and horizontal impact are the main causes of sliding instability of the broken blocks.When the dominant frequency of the kinetic energy of the broken block is within 20 Hz,the efects of ultra-low friction are more likely.
基金Supported by National Natural Science Foundation of China(Grant No.52175377)Chongqing Municipal Science Foundation(Grant No.CSTB2022NSCQ-LZX0080)+1 种基金Fundamental Research Funds for Central Universities(Grant Nos.2023CDJXY-026 and 2023CDJXY-021)National Science and Technology Major Project(Grant No.2017-VII-0002-0095).
文摘The low density and high corrosion resistance of titanium alloy make it a material with various applications in the aerospace industry. However, because of its high specifc strength and poor thermal conductivity, there are problems such as high cutting force, poor surface integrity, and high cutting temperature during conventional machining. As an advanced processing method with high efciency and low damage, laser-assisted machining can improve the machinability of titanium alloy. In this study, a picosecond pulse laser-assisted scratching (PPLAS) method considering both the temperature-dependent material properties and ultrashort pulse laser’s characteristics is frst proposed. Then, the efects of laser power, scratching depth, and scratching speed on the distribution of stress and temperature feld are investigated by simulation. Next, PPLAS experiments are conducted to verify the correctness of the simulation and reveal the removal behavior at various combinations of laser power and scratching depths. Finally, combined with simulated and experimental results, the removal mechanism under the two machining methods is illustrated. Compared with conventional scratching (CS), the tangential grinding force is reduced by more than 60% and the material removal degree is up to 0.948 during PPLAS, while the material removal is still primarily in the form of plastic removal. Grinding debris in CS takes the form of stacked fakes with a “fsh scale” surface, whereas it takes the form of broken serrations in PPLAS. This research can provide important guidance for titanium alloy grinding with high surface quality and low surface damage.
基金supported by the National Natural Science Foundation of China(NSFC,No.52171128)the Fundamental Research Project of Shenyang National Laboratory for Materials Science(No.L2019R18).
文摘Small specimens are increasingly being used in getting mechanical properties directly when there are limited materials to facilitate standard specimens,which play a great role in the rapid measurement of mechanical properties and residual life assessment of in-service reactor components.Although tensile and fatigue properties of the small specimens are investigated extensively,theoretical models for describing the mechanical properties of small specimens need to be established.Here,we conduct a systematic investigation of tensile and fatigue properties of pure Cu specimens with thicknesses ranging from 3 to 0.2 mm.The results show that the decrease in uniform elongation of the 0.2 mm-thick specimens is mainly due to the efects of grain boundary and free surface on the strain hardening rate.A modifed theoretical model correlated with the ratio of the surface grain layer thickness to the grain size is proposed to predict variation in yield strength of the small specimens more accurately.Furthermore,the mechanism for the diference in fatigue life between the 0.2 mm-thick specimen and other thicker specimens is elucidated.The Basquin equation-based model is presented as a potential way to evaluate the fatigue life of metals using small specimens.
基金Russian Science Foundation Grant No.14-15-00840Pstudying the laser-induced hydrodynamic processes was partly supported by Russian Foundation for Basic Research Grant No.17-02-00832.
文摘The bactericidal effect of laser radiation with a quartz fiber-based transmission system with a strong absorption coating converter against bacteria associated with urological stones has been studied.Gr am-negative rod Escherichia coli and the Gram-positive coccus Staphylococcus epi-dermidis,Staphylococcus aureus,Enterococcus faecalis and Enterococcus faecium were used in this study.Each bacterial species was treated by continuous-wave near infrared laser coupled with bare fiber tip or strongly absorption coating fiber tip.After treatment,the temperature of bacterial suspension was measured.In addition,the temperature dist ribution was analyzed.It has been shown that using laser with a strongly absorption coating fiber tip results in significant bactericidal effect.The decrease of the amount of E.coli and S.epidermidis was 100%after treatment with an output power of6 W of radiation at a wavelength of 0.97 pum for 40s.Number of S.aureus and Ent.facium colony-forming unit was reduced to 70%after same exposure.The peak temperature of bacterial suspension was 86℃ after treatment by laser with a strongly absorption coating fiber tip.Laser with a strongly absorpt ion coating fiber tip provides large scale hydrodynamic flows directed away from the fiber tip.The laser with a strongly absorption coating fiber tip has bactericidal effect.The main role is associated with the effect of high temperature,which,in the form of flow in a liquid medium,afects bacteria.
文摘We observed a phenomenon that different scattering components have different decorrelation time.Based on decorrelation time difference,we proposed a method to image an object hidden behind a turbid medium in a reflection mode.In order to suppress the big disturbance calused by reflection and back scattering,two framnes of speckles are recorded in sequence,and their difference is used for image reconstruction.Our method is immune to both medium motions and object movements.
基金the Chinese Scholarship Council(Grant No.202206240086)the National Natural Science Foundation of China(Grant No.82170432)programs from Science and Technology Department of Sichuan Province(Grant No.2020YFSY0024).
文摘The incre asing interest in RNA modifications has signifcantly advanced epigenomic and epitranscriptomic technologies.This study focuses on the immuno oncological impact of ALYREF in human cancer through a pan-cancer analysis,enhancing understanding of this gene's role in cancer.We observed differential ALYREF expression between tumor and normal samples,correl ating strongly with prognosis in various cancers,particularly kidney renal papillary cell carcinoma(KIRP)and liver hepatocellular carcinoma(LIHC).ALYREF showed a negative correlation with most tumor-infitrating cells in lung squamous cell carcinoma(LUSC)and lymphoid neoplasm difuse large B-cell lymphoma(DLBC),while positive correlations were noted in IIHC,kidney chromophobe(KICH),mesothelioma(MESO),KIRP,pheochromocytoma and paraganglioma(PARD),and glioma(GBMLGG).Aditionally,ALYREF expression was closely associated with tumor heterogeneity,stemness indices,and a high mutation rate in TP53 across these cancers.In conclusion,ALYREF may serve as an oncogenic biomarker in numerous cancers,meriting further research attention.
文摘Background Drug‑resistant epilepsy(DRE)exerts substantial clinical,humanistic and economic burdens on patients,their families and the healthcare system.Vagus nerve stimulation(VNS)has been extensively tested in clinical trial settings to decrease the frequency of seizures in patients with DRE who are not candidates for surgery;the results indicate promising efcacy and a well‑tolerated safety profle.However,real‑world evidence is still lacking.This retro‑spective study evaluated the safety and efcacy of VNS in patients with DRE.Methods The current study was a retrospective chart review of the medical records of children and adults with DRE treated with VNS between December 2006 and November 2022.The primary outcome of the present study was the percentage of patients who experienced a reduction in seizure frequency of more than 50%compared with the frequency at baseline(the period before VNS device insertion).Results A total of 103 patients were included.The percentage of patients who achieved a reduction of more than 50%in seizure frequency was 23%at six months,36%at 12 months,65%at 18 months,and 72%at 24 months.Similarly,the percentage of patients with complete resolution of interictal epileptiform discharges(IEDs)increased from 30%at six months to 60%after 24 months.The overall Quality of Life in Epilepsy(QOLIE‑31)score at the end of follow‑up was 39.46±13.68 points.Two patients(1.9%)reported experiencing side efects at the end of follow‑up.Conclusions VNS implementation led to a signifcant reduction in the seizure frequency and resolution of IEDs,with a well‑tolerated safety profle.The fndings highlight the potential role of VNS in managing DRE and warrant its consideration for treating patients with DRE.
基金supported by the National Natural Science Foundation of China(32001302)Startup Project for Doctor’s Scientifc Research of Binzhou University(2019Y35)the Innovation and Training Program of University Students of Shandong Province in 2021(S202110449140).
文摘Background Both increasing native species diversity and reducing nutrient availability can increase the ability of native plant communities to resist alien plant invasions. Furthermore, native species diversity and nutrient availabil-ity may interact to influence alien plant invasions. So far, however, little is known about the interactive effect of spe-cies diversity and nutrient availability on reproduction of alien invasive plants. We constructed native plant communi-ties with one, four or eight species under low and high nutrient supply and then let them be invaded by the invasive alien plant Bidens pilosa.Results At both high and low nutrient supply, increasing native species richness significantly increased aboveground biomass of the native plant community and decreased aboveground biomass and biomass proportion of the invader B. pilosa. Reproductive biomass of B. pilosa decreased significantly with increasing native species richness under high nutrient supply, but this effect was not observed under low nutrient supply. Net biodiversity effect on seed mass of B. pilosa decreased significantly with increasing native species diversity under high nutrient supply, but not under low nutrient supply. This was mainly because the selection effect became dominant with increasing species richness under high nutrient supply.Conclusions Our study suggest that native species richness and nutrient supply can interact to influence repro-duction of invasive alien plant species and that measures to help maintain a high level of native species richness and to reduce nutrient supply could be useful for efficient invasive plant control.
文摘Background Previous studies have found that patients with epilepsy are more likely to sufer impulsivity.However,the causal relationship between impulsivity and epilepsy is unknown.In this study,we conduct a bidirectional Mendelian randomization(MR)study to explore the causal relationship between impulsivity and epilepsy with recurrent seizure.Methods Data of the genome-wide association studies(GWAS)on 14 impulsivity traits and epilepsy were obtained from the GWAS catalog and UK Biobank.Inverse-variance weighted(IVW)and weighted median(WM)methods were utilized for MR estimates.IVW,MR-Egger regression,and MR-pleiotropy residual sum and outlier(MR-PRESSO)methods were used to assess heterogeneity and pleiotropy.Results Single-nucleotide polymorphisms(SNPs)related to the lack of perseverance were associated with a decreased risk of epilepsy with recurrent seizures according to the results of IVW(odd ratio[OR]=0.93,95%confdent interval[CI]=0.90-0.97,P=0.001)and WM(OR=0.93,95%CI=0.87-0.98,P=0.007).Meanwhile,heterogeneity was not observed with a Cochran Q-derived P value of 0.819 for MR egger and a P value of 0.808 for IVW.Pleiotropy was not found according to the MR-PRESSO(P=0.273).The other 13 impulsivity traits had no causal efect on epilepsy with recurrent seizures.Meanwhile,SNPs related with epilepsy with recurrent seizures had no causal efect on the 14 impulsivity traits.Conclusions This MR study suggests that lack of perseverance may be a protective factor against epilepsy with recurrent seizures.However,epilepsy with recurrent seizures does not afect impulsivity.
