H9N2 avian influenza viruses(AIVs)circulate globally in poultry and have become the dominant AIV subtype in China in recent years.Previously,we demonstrated that the H9N2 virus(A/chicken/Eastern China/SDKD1/2015)natur...H9N2 avian influenza viruses(AIVs)circulate globally in poultry and have become the dominant AIV subtype in China in recent years.Previously,we demonstrated that the H9N2 virus(A/chicken/Eastern China/SDKD1/2015)naturally harbors a mammalian-adaptive molecular factor(627K)in the PB2 protein and is weakly pathogenic in mice.Here,we focused on new markers for virulence in mammals.A mouse-adapted H9N2 virus was serially passaged in mice by infecting their lungs.As expected,infected mice showed clinical symptoms and died at passage six.A comparison between the wild-type and mouse-adapted virus sequences identified amino acid substitutions in the hemagglutinin(HA)protein.H9N2 viruses with the T187P t M227L double mutation exhibited an increased affinity to human-type(SAα2,6Gal)receptors and significantly enhanced viral attachment to mouse lung tissues,which contributed to enhancing viral replication and virulence in mice.Additionally,HA with the T187P t M227L mutation enabled H9N2 viral transmission in guinea pigs via direct contact.AIV pathogenicity in mice is a polygenic trait.Our results demonstrated that these HA mutations might be combined with PB2-627K to significantly increase H9N2 virulence in mice,and this enhanced virulence was achieved in other H9N2 AIVs by generating the same combination of mutations.In summary,our study identified novel key elements in the HA protein that are required for H9N2 pathogenicity in mice and provided valuable insights into pandemic preparedness against emerging H_(9)N_(2)strains.展开更多
Calcareous soil contains organic and inorganic carbon(C) pools,which both contribute to CO2 emission during closed-jar incubation. The mineralization of organic C and dissolution of inorganic C are both related to so...Calcareous soil contains organic and inorganic carbon(C) pools,which both contribute to CO2 emission during closed-jar incubation. The mineralization of organic C and dissolution of inorganic C are both related to soil moisture,but the exact effect of water content on CO2 emission from calcareous soil is unclear. The objective of this experiment was to determine the effect of soil water content(air-dried,30%,70%,and 100% water-holding capacity(WHC)),carbonate type(CaCO3 or MgCO3),and carbonate amount(0.0,1.0%,and 2.0%) on CO2 emission from calcareous soil during closed-jar incubation. Soil CO2 emission increased significantly as the water content increased to 70% WHC,regardless of whether or not the soil was amended with carbonates. Soil CO2 emission remained the same or increased slowly as the soil water content increased from 70% WHC to 100% WHC. When the water content was ≤30% WHC,soil CO2 emission from soil amended with 1.0% inorganic C was greater than that from unamended soil. When the soil water content was 70% or 100% WHC,CO2 emission from CaCO3 amended soil was greater than that from the control. Furthermore,CO2 emission from soil amended with 2.0% CaCO3 was greater than that from soil amended with 1.0% CaCO3. Soil CO2 emission was higher in the MgCO3 amended soil than from the unamended soil. Soil CO2 emission decreased as the MgCO3 content increased. Cumulative CO2 emission was 3-6 times higher from MgCO3 amended soil than from CaCO3 amended soil. There was significant interaction effect between soil moisture and carbonates on CO2 emission. Soil moisture plays an important role in CO2 emission from calcareous soil because it affects both biotic and abiotic processes during the closed-jar incubation.展开更多
With the rapid development of economy, industrial and agricultural pollutants have caused great damage to the ecological environment and the normal development of organisms, posing a serious threat to global public he...With the rapid development of economy, industrial and agricultural pollutants have caused great damage to the ecological environment and the normal development of organisms, posing a serious threat to global public health. Therefore, rapid and sensitive detection of pollutants is very important for environmental safety and people’s health. A stable multi-response fluorescence sensor(RhB@1) with dual emission characteristics was constructed by embedding Rh B vip molecules in Zn-MOF using a simple one-pot method. XRD, IR, XPS, Raman and other characterization methods were used to demonstrate the formation of composite materials. The sensor has two fluorescence emission peaks at 415 nm and 575nm under the excitation of 316 nm. It has high sensitivity and low detection limit(7.94 and 7.82 nmol/L,respectively) in the detection of fluazinam(FLU) and Fe^(3+). The mechanism of fluorescence quenching may be due to the synergistic effect of IFE and PET. Outstandingly, when ascorbate acid(AA) was added to the quenching system of Fe^(3+) and Rh B@1, its fluorescence gradually recovered, forming the unique“on-off-on” sensor. Therefore, RhB@1 has a fast fluorescence response and good stability, making it potentially useful in practical application and biosensors. More significantly, using Fe^(3+)and AA as chemical input signals, a binary intelligent logic gate device has been developed based on the “on-off-on” response mode of RhB@1, which extends the application of logic gate switching devices in the chemical field. In addition, a visual portable test paper with good selectivity and high sensitivity was developed, which can be used for rapid detection of FLU, showing its broad application prospect.展开更多
[Objectives]This study was conducted to explore the optimization of ultrasonic-assisted organic solvent extraction of pomegranate peel polyphenols(PPPs),and to study the protective effect of PPPs on acute alcoholic li...[Objectives]This study was conducted to explore the optimization of ultrasonic-assisted organic solvent extraction of pomegranate peel polyphenols(PPPs),and to study the protective effect of PPPs on acute alcoholic liver injury in mice.[Methods]The optimal extraction conditions of PPPs were determined by single factor and orthogonal experiments,and an acute alcoholic liver injury model in mice was established.Bifendate was used as the positive control group to investigate the protective effect of low,medium and high doses of PPPs on acute alcoholic liver injury.[Results]The optimum extraction process parameters were followed as 60%ethanol concentration,solid-liquid ratio of 1:40(w/v),extraction temperature of 50℃,and extraction time of 1.5 h,and the yield was 1.42%.The results of animal experiments showed that PPPs could effectively reduce the degree of alcoholic liver injury in mice,reduce the levels of serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST),and reduce the inflammation and necrosis of liver tissue in mice.Meanwhile,the total polyphenols from pomegranate peel also significantly reduced the expression levels of malondialdehyde(MDA),tumor necrosis factor(TNF-α)and interleukin-6(IL-6)in mice,and increased the levels of superoxide dismutase(SOD)and reduced glutathione(GSH)in liver tissue of mice,indicating its antioxidant and anti-inflammatory effects,further illustrating its protective effect on alcoholic liver injury.[Conclusions]PPPs could reduce the expression levels of TNF-α,IL-6 and MDA in mice,and increase the expression levels of SOD and GSH to achieve the protective effect on acute alcoholic liver injury in mice.This study will provide new ideas for the development of new anti-alcoholic liver injury drug resources.展开更多
Cloud water plays an important role in the global atmospheric water cycle and weather modification,but cloud is one of the most uncertain parameters in the study of weather and climate.The cloud water products from di...Cloud water plays an important role in the global atmospheric water cycle and weather modification,but cloud is one of the most uncertain parameters in the study of weather and climate.The cloud water products from different data sources may have considerable discrepancies.In this study,the total cloud liquid water(termed as cloud liquid water path,LWP)obtained from satellite observations[Advanced Himawari Imager(AHI)and Advanced Microwave Scanning Radiometer(AMSR)]and three sets of modern reanalysis data(ERA5,JRA-55,and MERRA-2)are compared and analyzed.Moreover,characteristics of vertical distributions of cloud liquid water content(LWC)in different regions over East Asia are analyzed by using the profile data from the reanalyses.The main findings are as follows:(1)in extensive warm marine clouds,AHI and AMSR have a good agreement(with the correlation coefficient larger than 0.7)but with an overestimation from AHI;(2)under warm cloud conditions,the LWP in ERA5shows a significant positive bias(about 0.065 kg m^(-2))over land,while MERRA-2 is closer to the satellite product compared with ERA5 and JRA-55;and(3)Southwest China(SW)is the area with most abundant LWC.The LWC is mainly concentrated in the middle and lower troposphere in the study area,and the LWC in ERA5 is higher than that in MERRA-2 and JRA-55.Overall,satellite observations and reanalyses exhibit significant inconsistency for cloud LWP,which needs further investigation and understanding.展开更多
Terahertz(THz)detectors with high sensitivity,fast response speed,room temperature operation,and self-powered feature are the key component for many THz applications.Microcavity resonators can effectively improve the ...Terahertz(THz)detectors with high sensitivity,fast response speed,room temperature operation,and self-powered feature are the key component for many THz applications.Microcavity resonators can effectively improve the sensitivity of THz detectors.However,it is difficult to precisely evaluate the microcavity resonator induced such improvement in experiment.Here,we realize a configurable microcavity–antenna-integrated graphene photothermoelectric(PTE)THz detector.Through the microcavity–antenna hybrid structure,THz radiations are localized and enhanced at one end of the graphene channel,and the temperature difference along the channel is greatly increased,resulting in the strong enhancement of PTE response.At the resonant frequency,the device has a high responsivity(976 V/W),low noise equivalent power(2.87 pW∕Hz1∕2),and fast response speed(300 ns)at room temperature and in zero-bias operation mode.The microcavity-induced peak enhancement factor of 13.14 is accurately extracted.The microcavity–antenna introduced enhancement is further confirmed by using a two-temperature heat transfer model.The strategy of using a configurable microcavity is useful for further optimizing THz detectors by introducing the critical coupling mechanism.展开更多
In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mech...In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mechanism of snowfall enhancement in stratiform clouds in the Bayanbulak test area of Xinjiang,China.The results indicated that the optimal seeding time was the early stages of weather system development.In this case,the optimal seeding zone was identified as the northwest of the test area,especially near the cloud top(altitudes between 3500 and 4000 m,temperatures range−11 to−15℃),and the ideal concentration of catalyst was with ice crystal density of 1.0×10^(7)kg^(−1)within the target area.Under such conditions,the total precipitation rate in the seeding-affected area increased to 50.1 mm h^(−1).The results also showed that the favorable seeding region was featured by high content of supercooled water and low population of natural ice crystals,where artificial ice crystals could substantially increase the snowfall.This augmentation typically appeared in a unimodal pattern,with the peak formed within 2–3 h after seeding.Seeding in the ice–water mixed zone of a supercooled cloud facilitated rapid ice crystal growth to snow-flake pieces via the Bergeron process,which in turn consumed more supercooled water via collision–coalescence with cloud water droplets.Simultaneously,the intensive consumption of supercooled water impeded the riming process and reduced the formation of graupel particles within the cloud.The dispersion of artificial ice crystals extended over tens of kilometers horizontally;however,in the vertical direction most particles remained approximately 1 km below the seeding layer,due to limited vertical ascent rate in the stratiform clouds restricting upward movement of artificial ice crystals.The above results help better understand the snowfall enhancement mechanism in stratiform clouds and facilitate related weather modification practice.展开更多
Decades have passed since the first discovery of H10-subtype avian influenza virus(AIV) in chickens in 1949,and it has been detected in many species including mammals such as minks,pigs,seals and humans.Cases of human...Decades have passed since the first discovery of H10-subtype avian influenza virus(AIV) in chickens in 1949,and it has been detected in many species including mammals such as minks,pigs,seals and humans.Cases of human infections with H10N8viruses identified in China in 2013 have raised widespread attention.Two novel reassortant H10N3 viruses were isolated from chickens in December 2019 in eastern China during routine surveillance for AIVs.The internal genes of these viruses were derived from genotype S(G57) H9N2 and were consistent with H5N6,H7N9 and H10N8,which cause fatal infections in humans.Their viral pathogenicity and transmissibility were further studied in different animal models.The two H10N3 isolates had low pathogenicity in chickens and were transmitted between chickens via direct contact.These viruses were highly pathogenic in mice and could be transmitted between guinea pigs via direct contact and respiratory droplets.More importantly,these viruses can bind to both human-type SAα-2,6-Gal receptors and avian-type SAα-2,3-Gal receptors.Asymptomatic shedding in chickens and good adaptability to mammals of these H10N3 isolates would make it easier to transmit to humans and pose a threat to public health.展开更多
The water in the air is composed of water vapor and hydrometeors,which are inseparable in the global atmosphere.Precipitation basically comes from hydrometeors instead of directly from water vapor,but hydrometeors are...The water in the air is composed of water vapor and hydrometeors,which are inseparable in the global atmosphere.Precipitation basically comes from hydrometeors instead of directly from water vapor,but hydrometeors are rarely focused on in previous studies.When assessing the maximum potential precipitation,it is necessary to quantify the total amount of hydrometeors present in the air within an area for a certain period of time.Those hydrometeors that have not participated in precipitation formation in the surface,suspending in the atmosphere to be exploited,are defined as the cloud water resource(CWR).Based on the water budget equations,we defined 16 terms(including 12 independent ones)respectively related to the hydrometeors,water vapor,and total water substance in the atmosphere,and 12 characteristic variables related to precipitation and CWR such as precipitation efficiency(PE)and renewal time(RT).Correspondingly,the CWR contributors are grouped into state terms,advection terms,and source/sink terms.Two methods are developed to quantify the CWR(details of which are presented in the companion paper)with satellite observations,atmospheric reanalysis data,precipitation products,and cloud resolving models.The CWR and related variables over North China in April and August 2017 are thus derived.The results show that CWR has the same order of magnitude as surface precipitation(Ps).The hydrometers converted from water vapor(Cvh)during the condensation process is the primary source of precipitation.It is highly correlated with Ps and contributes the most to the CWR over a large region.The state variables and advection terms of hydrometeors are two orders of magnitude lower than the corresponding terms of water vapor.The atmospheric hydrometeors can lead to higher PE than water vapor(several tens of percent versus a few percent),with a shorter RT(only a few hours versus several days).For daily CWR,the state terms are important,but for monthly and longer-time mean CWR,the source/sink terms(i.e.,cloud microphysical processes)contribute the largest;meanwhile,the advection terms contribute less for larger study areas.展开更多
Based on the concepts of cloud water resource(CWR)and related variables proposed in the first part of this study,this paper provides details of two methods to quantify the CWR.One is diagnostic quantification(CWR-DQ)b...Based on the concepts of cloud water resource(CWR)and related variables proposed in the first part of this study,this paper provides details of two methods to quantify the CWR.One is diagnostic quantification(CWR-DQ)based on satellite observations,precipitation products,and atmospheric reanalysis data;and the other is numerical quantification(CWR-NQ)based on a cloud resolving model developed at the Chinese Academy of Meteorological Sciences(CAMS).The two methods are applied to quantify the CWR in April and August 2017 over North China,and the results are evaluated against all available observations.Main results are as follows.(1)For the CWR-DQ approach,reference cloud profiles are firstly derived based on the Cloud Sat/CALIPSO joint satellite observations for 2007–2010.The NCEP/NCAR reanalysis data in 2000–2017 are then employed to produce three-dimensional cloud fields.The budget/balance equations of atmospheric water substance are lastly used,together with precipitation observations,to retrieve CWR and related variables.It is found that the distribution and vertical structure of clouds obtained by the diagnostic method are consistent with observations.(2)For the CWR-NQ approach,it assumes that the cloud resolving model is able to describe the cloud microphysical processes completely and precisely,from which four-dimensional distributions of atmospheric water vapor,hydrometeors,and wind fields can be obtained.The data are then employed to quantify the CWR and related terms/quantities.After one-month continuous integration,the mass of atmospheric water substance becomes conserved,and the tempospatial distributions of water vapor,hydrometeors/cloud water,and precipitation are consistent with observations.(3)Diagnostic values of the difference in the transition between hydrometeors and water vapor(Cvh-Chv)and the surface evaporation(Es)are well consistent with their numerical values.(4)Correlation and bias analyses show that the diagnostic CWR contributors are well correlated with observations,and match their numerical counterparts as well,indicating that the CWR-NQ and CWR-DQ methods are reasonable.(5)Underestimation of water vapor converted from hydrometeors(Chv)is a shortcoming of the CWR-DQ method,which may be rectified by numerical quantification results or by use of advanced observations on higher spatiotemporal resolutions.展开更多
Based on the concept of cloud water resource(CWR)and the cloud microphysical scheme developed by the Chinese Academy of Meteorological Sciences(CAMS),a coupled mesoscale and cloud-resolving model system is developed i...Based on the concept of cloud water resource(CWR)and the cloud microphysical scheme developed by the Chinese Academy of Meteorological Sciences(CAMS),a coupled mesoscale and cloud-resolving model system is developed in the study for CWR numerical quantification(CWR-NQ)in North China for 2017.The results show that(1)the model system is stable and capable for performing 1-yr continuous simulation with a water budget error of less than 0.2%,which indicates a good water balance.(2)Compared with the observational data,it is confirmed that the simulating capability of the CWR-NQ approach is decent for the spatial distribution of yearly cumulative precipitation,daily precipitation intensity,yearly average spatial distribution of water vapor.(3)Compared with the CWR diagnostic quantification(CWR-DQ),the results from the CWR-NQ differ mainly in cloud condensation and cloud evaporation.However,the deviation of the net condensation(condensation minus evaporation)between the two methods is less than 1%.For other composition variables,such as water vapor advection,surface evaporation,precipitation,cloud condensation,and total atmospheric water substances,the relative differences between the CWR-NQ and the CWR-DQ are less than 5%.(4)The spatiotemporal features of the CWR in North China are also studied.The positive correlation between water vapor convergence and precipitation on monthly and seasonal scales,and the lag of precipitation relative to water vapor convergence on hourly and daily scales are analyzed in detail,indicating the significance of the state term on hourly and daily scales.The effects of different spatial scales on the state term,advection term,source-sink term,and total amount are analyzed.It is shown that the advective term varies greatly at different spatiotemporal scales,which leads to differences at different spatiotemporal scales in CWR and related characteristic quantities.展开更多
We report a novel method for rapid,colorimetric detection of a specific deoxyribonucleic acid(DNA)sequence by carrying out a polymerase chain reaction in the presence of gold nanoparticles functionalized with two prim...We report a novel method for rapid,colorimetric detection of a specific deoxyribonucleic acid(DNA)sequence by carrying out a polymerase chain reaction in the presence of gold nanoparticles functionalized with two primers.Extension of the primers when the target DNA is present as a template during the polymerase chain reaction process affords the complementary sequences on the gold nanoparticle surfaces and results in the formation of gold nanoparticle aggregates with a concomitant color change from red to pinkish/purple.This method provides a convenient and straightforward solution for ultrasensitive DNA detection without any further post-treatment of the polymerase chain reaction products being necessary,and is a promising tool for rapid disease diagnostics and gene sequencing.展开更多
High-dimensional entanglement is of great importance in quantum communications and can be realized by encoding information on multiple degrees of freedom(Do Fs)of the photons.Conventionally,the realization of such hig...High-dimensional entanglement is of great importance in quantum communications and can be realized by encoding information on multiple degrees of freedom(Do Fs)of the photons.Conventionally,the realization of such high-dimensional entanglement involves different combinations of bulky optical elements.In this work,we present the use of a single dielectric metasurface to generate high-dimensional entanglement by modulating multi-Do Fs of photons.By sending one of the polarization-entangled photons to interact with the metasurface,we encode path,spin angular momentum,and orbital angular momentum information to the original state.We achieve a four-qubit quantum state in the experiment.To verify it,we experimentally demonstrate the nonlocal correlations between the two photons by recording the correlated images,and we also perform a quantum state tomography measurement.This scheme can be applied to on-chip quantum state manipulation,which is promising in quantum communication with integrated components.展开更多
Identifying supercooled liquid water(SLW)in clouds is critical for weather modification,aviation safety,and atmospheric radiation calculations.Currently,aircraft identification in the SLW area mostly depends on empric...Identifying supercooled liquid water(SLW)in clouds is critical for weather modification,aviation safety,and atmospheric radiation calculations.Currently,aircraft identification in the SLW area mostly depends on emprical estimation of cloud particle number concentration(N_(c))in China,and scientific verification and quantitative identification criteria are urgently needed.In this study,the observations are from the Fast Cloud Droplets Probe,Rosemount ice detector(RICE),and Cloud Particle Imager(CP_(i))onboard a King Air aircraft during seven flights in 2018 and 2019 over central and eastern China.Based on this,the correlation among N_(c),the proportion of spherical particles(P_(s)),and the probability of icing(P_(i))in supercooled stratiform and cumulus-stratus clouds is statistically analyzed.Subsequently,this study proposes a method to identify SLW areas using N_(c) in combination with ambient temperature.The reliability of this method is evaluated through the true skill statistics(TSS)and threat score(TS)methods.Numerous airborne observations during the seven flights reveal a strong correlation among Nc,P_(s),and P_(i)at the temperature from 0 to−18°C.When Nc is greater than a certain threshold of 5 cm^(−3),there is always the SLW,i.e.,P_(i)and P_(s)are high.Evaluation results demonstrate that the TSS and TS values for Nc=5 cm^(−3)are higher than those for Nc<5 cm^(−3),and a larger Nc threshold(>5 cm^(−3))corresponds to a higher SLW identification hit rate and a higher SLW content.Therefore,Nc=5 cm^(−3)can be used as the minimum criterion for identifying the SLW in clouds at temperature lower than 0°C.The SLW identification method proposed in this study is especially helpful in common situations where aircraft are equipped with only Nc probes and without the CP_(i)and RICE.展开更多
By using the diagnostic quantification method for cloud water resource(CWR),the three-dimensional(3D)cloud fields of 1°×1°resolution during 2000-2019 in China are firstly obtained based on the NCEP rean...By using the diagnostic quantification method for cloud water resource(CWR),the three-dimensional(3D)cloud fields of 1°×1°resolution during 2000-2019 in China are firstly obtained based on the NCEP reanalysis data and related satellite data.Then,combined with the Global Precipitation Climatology Project(GPCP)products,a 1°×1°gridded CWR dataset of China in recent 20 years is established.On this basis,the monthly and annual CWR and related variables in China and its six weather modification operation sub-regions are obtained,and the CWR characteristics in different regions are analyzed finally.The results show that in the past 20 years,the annual total amount of atmospheric hydrometeors(GM_(h))and water vapor(GM_(v))in the Chinese mainland are about 838.1 and 3835.9 mm,respectively.After deducting the annual mean precipitation of China(P_(s),661.7 mm),the annual CWR is about 176.4 mm.Among the six sub-regions,the southeast region has the largest amount of cloud condensation(C_(vh))and precipitation,leading to the largest GM_(h) and CWR there.In contrast,the annual P_(s),GM_(h),and CWR are all the least in the northwest region.Furthermore,the monthly and interannual variation trends of P_(s),C_(vh),and GM_(h) in different regions are identical,and the evolution characteristics of CWR are also consistent with the hydrometeor inflow(Q_(hi)).For the north,northwest,and northeast regions,in spring and autumn the precipitation efficiency of hydrometeors(PEh)is not high(20%-60%),the renewal time of hydrometeors(RT_(h))is relatively long(5-25 h),and GM_(h) is relatively high.Therefore,there is great potential for the development of CWR through artificial precipitation enhancement(APE).For the central region,spring,autumn,and winter are suitable seasons for CWR development.For the southeast and southwest regions,P_(s) and PE_(h) in summer are so high that the development of CWR should be avoided.For different spatial scales,there are significant differences in the characteristics of CWR.展开更多
To explore the key technologies of artificial weather modification for specific targets(e.g.,a stadium)and improve the efficiency of artificial rainfall modification for major events,this study conducts an artificial ...To explore the key technologies of artificial weather modification for specific targets(e.g.,a stadium)and improve the efficiency of artificial rainfall modification for major events,this study conducts an artificial rainfall reduction experiment for the closing ceremony of Nanjing Youth Olympic Games on 28 August 2014.Satellite retrievals,radar observations,sounding data,and other sources of information as well as Cloud and Precipitation Accurate Analysis System(CPAS)are used in this study.The main conclusions are as follows.(1)On 28 August 2014,a large-scale cumulus cloud system with mixed-phase stratocumulus and stratus precipitation was observed.This system was influenced by the weak shear of a low-level trough and the precipitation was dominated by cold clouds with dry layers between clouds.Thereby,we adopted the crystal-priming over-catalytic hypothesis and conducted a rocket-catalytic rain abatement operation at a certain distance(100–25 km)from the stadium.Rocket shootings of different intensities were implemented for two echoes that affected the stadium successively(two rounds of 15 rocket shootings within15 min for an isolated weak echo IA;multiple rounds of 156 rocket shootings within 80 min for a strong echo IB).Amazingly,after the shootings with the catalysis in the air,reflectivity of the two echoes was reduced at all altitudes with the most significant reduction at the 2-km altitude,and the time needed for the obvious reduction was 40 min.The most obvious reduction of the two echoes then maintained for 60 and 53 min,respectively,and the operation time needed for the echo zone to recover after the stop of rocket shooting was 108 min for echo IA and 90 min for echo IB.The two echoes moving across the stadium during the time period of the closing ceremony(2000–2130 local time)were at their minimal strengths,with almost no echo over the target stadium.This demonstrates that the rocket shooting strategy of over-crystallization catalysis is effective,and the shooting site,time,and dose are reasonable.The following technical parameters were used during this experiment.At about 80–25 km away from the target stadium in the west,the rocket shooting lasted for 15–80 min and the doses were not less than 1 shot min~(-1)(1 shot min~(-1)for echo IA,2.25 shots min~(-1)for echo IB).The attenuation rate was 0.21 dBZ min~(-1)for the average 15 dBZ of echo IA.For the average 25 dBZ of echo IB,the attenuation rate was 0.27 dBZ min~(-1).The above technical settings helped achieve the goal of reducing rain over the stadium to almost zero for nearly 1-h period during the critical time of the event.展开更多
Emerging persistent memory technologies,like PCM and 3D XPoint,offer numerous advantages,such as higher density,larger capacity,and better energy efficiency,compared with the DRAM.However,they also have some drawbacks...Emerging persistent memory technologies,like PCM and 3D XPoint,offer numerous advantages,such as higher density,larger capacity,and better energy efficiency,compared with the DRAM.However,they also have some drawbacks,e.g.,slower access speed,limited write endurance,and unbalanced read/write latency.Persistent memory technologies provide both great opportunities and challenges for operating systems.As a result,a large number of solutions have been proposed.With the increasing number and complexity of problems and approaches,we believe this is the right moment to investigate and analyze these works systematically.To this end,we perform a comprehensive and in-depth study on operating system support for persistent memory within three steps.First,we present an overview of how to build the operating system on persistent memory from three perspectives:system abstraction,crash consistency,and system reliability.Then,we classify the existing research works into three categories:storage stack,memory manager,and OS-bypassing library.For each category,we summarize the major research topics and discuss these topics deeply.Specifically,we present the challenges and opportunities in each topic,describe the contributions and limitations of proposed approaches,and compare these solutions in different dimensions.Finally,we also envision the future operating system based on this study.展开更多
Topological insulators represent a new quantum phase of matter with spin-polarized surface states that are protected from backscattering, exhibiting electronic responses to light, such as topological quantum phase tra...Topological insulators represent a new quantum phase of matter with spin-polarized surface states that are protected from backscattering, exhibiting electronic responses to light, such as topological quantum phase transitions. However, the effects of high-frequency driving topological intrinsic systems have remained largely unexplored challenges experimentally for high-sensitivity terahertz detection. In this study, by integrating Sb2Te3 topological insulators with subwavelength metal antennas through micro-nano processing, a high-frequency terahertz detector with high sensitivity is proposed. The enhanced response originates from the asymmetric scattering of the surface electrons in the Sb_(2)Te_(3) flakes induced by the terahertz wave. The device displays room-temperature photodetection with a responsivity of 192 mA/W and equivalent noise power of less than 0.35 nW/Hz^(1/2) in the frequency range from 0.02 to 0.3 THz. These results pave the way for the exploitation of topological insulators for high-frequency operation in real-time imaging within long-wavelength optoelectronics.展开更多
Currently,security-critical server programs are well protected by various defense techniques,such as Address Space Layout Randomization(ASLR),eXecute Only Memory(XOM),and Data Execution Prevention(DEP),against modern ...Currently,security-critical server programs are well protected by various defense techniques,such as Address Space Layout Randomization(ASLR),eXecute Only Memory(XOM),and Data Execution Prevention(DEP),against modern code-reuse attacks like Return-oriented Programming(ROP)attacks.Moreover,in these victim programs,most syscall instructions lack the following ret instructions,which prevents attacks to stitch multiple system calls to implement advanced behaviors like launching a remote shell.Lacking this kind of gadget greatly constrains the capability of code-reuse attacks.This paper proposes a novel code-reuse attack method called Signal Enhanced Blind Return Oriented Programming(SeBROP)to address these challenges.Our SeBROP can initiate a successful exploit to server-side programs using only a stack overflow vulnerability.By leveraging a side-channel that exists in the victim program,we show how to find a variety of gadgets blindly without any pre-knowledges or reading/disassembling the code segment.Then,we propose a technique that exploits the current vulnerable signal checking mechanism to realize the execution flow control even when ret instructions are absent.Our technique can stitch a number of system calls without returns,which is more superior to conventional ROP attacks.Finally,the SeBROP attack precisely identifies many useful gadgets to constitute a Turing-complete set.SeBROP attack can defeat almost all state-of-the-art defense techniques.The SeBROP attack is compatible with both modern 64-bit and 32-bit systems.To validate its effectiveness,We craft three exploits of the SeBROP attack for three real-world applications,i.e.,32-bit Apache 1.3.49,32-bit ProFTPD 1.3.0,and 64-bit Nginx 1.4.0.Experimental results demonstrate that the SeBROP attack can successfully spawn a remote shell on Nginx,ProFTPD,and Apache with less than 8500/4300/2100 requests,respectively.展开更多
基金supported by the National Key R&D Program of China[grant number 2022YFF0801301]the National Natural Science Foundation of China[grant number 41575033]+1 种基金the Fengyun Satellite Application Pioneer Project[grant number FY-APP-2022.0111]the Natural Science Foundation of Jiangsu Province[grant number BK20231148]。
基金supported by the National Key Research and Development Project of China:2021YFD1800202by the National Natural Science Foundation of China:31772755,32072892,32072832+1 种基金by the Earmarked Fund for China Agriculture Reasearch System:CARS-40by the Priorty Academic Program Development of Jiangsu Higher Education Institutions(PAPD).
文摘H9N2 avian influenza viruses(AIVs)circulate globally in poultry and have become the dominant AIV subtype in China in recent years.Previously,we demonstrated that the H9N2 virus(A/chicken/Eastern China/SDKD1/2015)naturally harbors a mammalian-adaptive molecular factor(627K)in the PB2 protein and is weakly pathogenic in mice.Here,we focused on new markers for virulence in mammals.A mouse-adapted H9N2 virus was serially passaged in mice by infecting their lungs.As expected,infected mice showed clinical symptoms and died at passage six.A comparison between the wild-type and mouse-adapted virus sequences identified amino acid substitutions in the hemagglutinin(HA)protein.H9N2 viruses with the T187P t M227L double mutation exhibited an increased affinity to human-type(SAα2,6Gal)receptors and significantly enhanced viral attachment to mouse lung tissues,which contributed to enhancing viral replication and virulence in mice.Additionally,HA with the T187P t M227L mutation enabled H9N2 viral transmission in guinea pigs via direct contact.AIV pathogenicity in mice is a polygenic trait.Our results demonstrated that these HA mutations might be combined with PB2-627K to significantly increase H9N2 virulence in mice,and this enhanced virulence was achieved in other H9N2 AIVs by generating the same combination of mutations.In summary,our study identified novel key elements in the HA protein that are required for H9N2 pathogenicity in mice and provided valuable insights into pandemic preparedness against emerging H_(9)N_(2)strains.
基金supported by the National Natural Science Foundation of China(40773057)the National Technology R&D Pillar Program in the 12th Five-Year Plan of China(2012BAD15B04)
文摘Calcareous soil contains organic and inorganic carbon(C) pools,which both contribute to CO2 emission during closed-jar incubation. The mineralization of organic C and dissolution of inorganic C are both related to soil moisture,but the exact effect of water content on CO2 emission from calcareous soil is unclear. The objective of this experiment was to determine the effect of soil water content(air-dried,30%,70%,and 100% water-holding capacity(WHC)),carbonate type(CaCO3 or MgCO3),and carbonate amount(0.0,1.0%,and 2.0%) on CO2 emission from calcareous soil during closed-jar incubation. Soil CO2 emission increased significantly as the water content increased to 70% WHC,regardless of whether or not the soil was amended with carbonates. Soil CO2 emission remained the same or increased slowly as the soil water content increased from 70% WHC to 100% WHC. When the water content was ≤30% WHC,soil CO2 emission from soil amended with 1.0% inorganic C was greater than that from unamended soil. When the soil water content was 70% or 100% WHC,CO2 emission from CaCO3 amended soil was greater than that from the control. Furthermore,CO2 emission from soil amended with 2.0% CaCO3 was greater than that from soil amended with 1.0% CaCO3. Soil CO2 emission was higher in the MgCO3 amended soil than from the unamended soil. Soil CO2 emission decreased as the MgCO3 content increased. Cumulative CO2 emission was 3-6 times higher from MgCO3 amended soil than from CaCO3 amended soil. There was significant interaction effect between soil moisture and carbonates on CO2 emission. Soil moisture plays an important role in CO2 emission from calcareous soil because it affects both biotic and abiotic processes during the closed-jar incubation.
基金supported by National Natural Science Foundation of China(No.21763028)Science and Technology project of Shaanxi Province(Nos.2022NY-071,2022QFY07-05,2022JZ-49)。
文摘With the rapid development of economy, industrial and agricultural pollutants have caused great damage to the ecological environment and the normal development of organisms, posing a serious threat to global public health. Therefore, rapid and sensitive detection of pollutants is very important for environmental safety and people’s health. A stable multi-response fluorescence sensor(RhB@1) with dual emission characteristics was constructed by embedding Rh B vip molecules in Zn-MOF using a simple one-pot method. XRD, IR, XPS, Raman and other characterization methods were used to demonstrate the formation of composite materials. The sensor has two fluorescence emission peaks at 415 nm and 575nm under the excitation of 316 nm. It has high sensitivity and low detection limit(7.94 and 7.82 nmol/L,respectively) in the detection of fluazinam(FLU) and Fe^(3+). The mechanism of fluorescence quenching may be due to the synergistic effect of IFE and PET. Outstandingly, when ascorbate acid(AA) was added to the quenching system of Fe^(3+) and Rh B@1, its fluorescence gradually recovered, forming the unique“on-off-on” sensor. Therefore, RhB@1 has a fast fluorescence response and good stability, making it potentially useful in practical application and biosensors. More significantly, using Fe^(3+)and AA as chemical input signals, a binary intelligent logic gate device has been developed based on the “on-off-on” response mode of RhB@1, which extends the application of logic gate switching devices in the chemical field. In addition, a visual portable test paper with good selectivity and high sensitivity was developed, which can be used for rapid detection of FLU, showing its broad application prospect.
基金Supported by Provincial Key College Students Innovation and Entrepreneurship Training Program Project (202211834033).
文摘[Objectives]This study was conducted to explore the optimization of ultrasonic-assisted organic solvent extraction of pomegranate peel polyphenols(PPPs),and to study the protective effect of PPPs on acute alcoholic liver injury in mice.[Methods]The optimal extraction conditions of PPPs were determined by single factor and orthogonal experiments,and an acute alcoholic liver injury model in mice was established.Bifendate was used as the positive control group to investigate the protective effect of low,medium and high doses of PPPs on acute alcoholic liver injury.[Results]The optimum extraction process parameters were followed as 60%ethanol concentration,solid-liquid ratio of 1:40(w/v),extraction temperature of 50℃,and extraction time of 1.5 h,and the yield was 1.42%.The results of animal experiments showed that PPPs could effectively reduce the degree of alcoholic liver injury in mice,reduce the levels of serum alanine aminotransferase(ALT)and aspartate aminotransferase(AST),and reduce the inflammation and necrosis of liver tissue in mice.Meanwhile,the total polyphenols from pomegranate peel also significantly reduced the expression levels of malondialdehyde(MDA),tumor necrosis factor(TNF-α)and interleukin-6(IL-6)in mice,and increased the levels of superoxide dismutase(SOD)and reduced glutathione(GSH)in liver tissue of mice,indicating its antioxidant and anti-inflammatory effects,further illustrating its protective effect on alcoholic liver injury.[Conclusions]PPPs could reduce the expression levels of TNF-α,IL-6 and MDA in mice,and increase the expression levels of SOD and GSH to achieve the protective effect on acute alcoholic liver injury in mice.This study will provide new ideas for the development of new anti-alcoholic liver injury drug resources.
基金Supported by the National Natural Science Foundation of China(42205044)National Key Research and Development Program of China(2024YFF1308202)+2 种基金Fengyun Application Pioneer Project(FY-APP-2022.0111)Project for the Capacity Construction of Weather Modification in Southwest China[SCIT-ZG(Z)-2024100001]Wuxi University Research Start-up Fund for Introduced Talents(2024r045)。
文摘Cloud water plays an important role in the global atmospheric water cycle and weather modification,but cloud is one of the most uncertain parameters in the study of weather and climate.The cloud water products from different data sources may have considerable discrepancies.In this study,the total cloud liquid water(termed as cloud liquid water path,LWP)obtained from satellite observations[Advanced Himawari Imager(AHI)and Advanced Microwave Scanning Radiometer(AMSR)]and three sets of modern reanalysis data(ERA5,JRA-55,and MERRA-2)are compared and analyzed.Moreover,characteristics of vertical distributions of cloud liquid water content(LWC)in different regions over East Asia are analyzed by using the profile data from the reanalyses.The main findings are as follows:(1)in extensive warm marine clouds,AHI and AMSR have a good agreement(with the correlation coefficient larger than 0.7)but with an overestimation from AHI;(2)under warm cloud conditions,the LWP in ERA5shows a significant positive bias(about 0.065 kg m^(-2))over land,while MERRA-2 is closer to the satellite product compared with ERA5 and JRA-55;and(3)Southwest China(SW)is the area with most abundant LWC.The LWC is mainly concentrated in the middle and lower troposphere in the study area,and the LWC in ERA5 is higher than that in MERRA-2 and JRA-55.Overall,satellite observations and reanalyses exhibit significant inconsistency for cloud LWP,which needs further investigation and understanding.
基金National Key Research and Development Program of China(2023YFF0719200)National Natural Science Foundation of China(61731020,61988102)Science and Technology Commission of Shanghai Municipality(21S31907400)。
文摘Terahertz(THz)detectors with high sensitivity,fast response speed,room temperature operation,and self-powered feature are the key component for many THz applications.Microcavity resonators can effectively improve the sensitivity of THz detectors.However,it is difficult to precisely evaluate the microcavity resonator induced such improvement in experiment.Here,we realize a configurable microcavity–antenna-integrated graphene photothermoelectric(PTE)THz detector.Through the microcavity–antenna hybrid structure,THz radiations are localized and enhanced at one end of the graphene channel,and the temperature difference along the channel is greatly increased,resulting in the strong enhancement of PTE response.At the resonant frequency,the device has a high responsivity(976 V/W),low noise equivalent power(2.87 pW∕Hz1∕2),and fast response speed(300 ns)at room temperature and in zero-bias operation mode.The microcavity-induced peak enhancement factor of 13.14 is accurately extracted.The microcavity–antenna introduced enhancement is further confirmed by using a two-temperature heat transfer model.The strategy of using a configurable microcavity is useful for further optimizing THz detectors by introducing the critical coupling mechanism.
基金Supported by the Scientific Research Project of the Bayingol Mongolian Autonomous Prefecture in Xinjiang(202318)China Meteorological Administration(CMA)Weather Modification Centre Innovation Team Project(WMC2023IT01)CMA Key Innovation Team Project(CMA2022ZD10).
文摘In this study,we employed a three-dimensional mesoscale cold-cloud seeding model to simulate the microphysical impacts of artificial ice crystals used as cloud seeding catalysts.Our objective was to elucidate the mechanism of snowfall enhancement in stratiform clouds in the Bayanbulak test area of Xinjiang,China.The results indicated that the optimal seeding time was the early stages of weather system development.In this case,the optimal seeding zone was identified as the northwest of the test area,especially near the cloud top(altitudes between 3500 and 4000 m,temperatures range−11 to−15℃),and the ideal concentration of catalyst was with ice crystal density of 1.0×10^(7)kg^(−1)within the target area.Under such conditions,the total precipitation rate in the seeding-affected area increased to 50.1 mm h^(−1).The results also showed that the favorable seeding region was featured by high content of supercooled water and low population of natural ice crystals,where artificial ice crystals could substantially increase the snowfall.This augmentation typically appeared in a unimodal pattern,with the peak formed within 2–3 h after seeding.Seeding in the ice–water mixed zone of a supercooled cloud facilitated rapid ice crystal growth to snow-flake pieces via the Bergeron process,which in turn consumed more supercooled water via collision–coalescence with cloud water droplets.Simultaneously,the intensive consumption of supercooled water impeded the riming process and reduced the formation of graupel particles within the cloud.The dispersion of artificial ice crystals extended over tens of kilometers horizontally;however,in the vertical direction most particles remained approximately 1 km below the seeding layer,due to limited vertical ascent rate in the stratiform clouds restricting upward movement of artificial ice crystals.The above results help better understand the snowfall enhancement mechanism in stratiform clouds and facilitate related weather modification practice.
基金supported by the National Key Research and Development Project of China (2016YFD0500202-1,2016YFD0501601)the National Natural Science Foundation of China(31772755)+3 种基金Jiangsu Provincial Natural Science Fund for Excellent Young Scholars (BK20170068)the Earmarked Fund For China Agriculture Research System (CARS-40)the Open Project Program of Jiangsu Key Laboratory of Zoonosis (R1808)the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)。
文摘Decades have passed since the first discovery of H10-subtype avian influenza virus(AIV) in chickens in 1949,and it has been detected in many species including mammals such as minks,pigs,seals and humans.Cases of human infections with H10N8viruses identified in China in 2013 have raised widespread attention.Two novel reassortant H10N3 viruses were isolated from chickens in December 2019 in eastern China during routine surveillance for AIVs.The internal genes of these viruses were derived from genotype S(G57) H9N2 and were consistent with H5N6,H7N9 and H10N8,which cause fatal infections in humans.Their viral pathogenicity and transmissibility were further studied in different animal models.The two H10N3 isolates had low pathogenicity in chickens and were transmitted between chickens via direct contact.These viruses were highly pathogenic in mice and could be transmitted between guinea pigs via direct contact and respiratory droplets.More importantly,these viruses can bind to both human-type SAα-2,6-Gal receptors and avian-type SAα-2,3-Gal receptors.Asymptomatic shedding in chickens and good adaptability to mammals of these H10N3 isolates would make it easier to transmit to humans and pose a threat to public health.
基金Supported by the National Key Research and Development Program of China(2016YFA0601701)National High Technology Research and Development Program of China(2012AA120902)。
文摘The water in the air is composed of water vapor and hydrometeors,which are inseparable in the global atmosphere.Precipitation basically comes from hydrometeors instead of directly from water vapor,but hydrometeors are rarely focused on in previous studies.When assessing the maximum potential precipitation,it is necessary to quantify the total amount of hydrometeors present in the air within an area for a certain period of time.Those hydrometeors that have not participated in precipitation formation in the surface,suspending in the atmosphere to be exploited,are defined as the cloud water resource(CWR).Based on the water budget equations,we defined 16 terms(including 12 independent ones)respectively related to the hydrometeors,water vapor,and total water substance in the atmosphere,and 12 characteristic variables related to precipitation and CWR such as precipitation efficiency(PE)and renewal time(RT).Correspondingly,the CWR contributors are grouped into state terms,advection terms,and source/sink terms.Two methods are developed to quantify the CWR(details of which are presented in the companion paper)with satellite observations,atmospheric reanalysis data,precipitation products,and cloud resolving models.The CWR and related variables over North China in April and August 2017 are thus derived.The results show that CWR has the same order of magnitude as surface precipitation(Ps).The hydrometers converted from water vapor(Cvh)during the condensation process is the primary source of precipitation.It is highly correlated with Ps and contributes the most to the CWR over a large region.The state variables and advection terms of hydrometeors are two orders of magnitude lower than the corresponding terms of water vapor.The atmospheric hydrometeors can lead to higher PE than water vapor(several tens of percent versus a few percent),with a shorter RT(only a few hours versus several days).For daily CWR,the state terms are important,but for monthly and longer-time mean CWR,the source/sink terms(i.e.,cloud microphysical processes)contribute the largest;meanwhile,the advection terms contribute less for larger study areas.
基金Supported by the National Key Research and Development Program of China(2016YFA0601701)National High Technology Research and Development Program of China(2012AA120902)。
文摘Based on the concepts of cloud water resource(CWR)and related variables proposed in the first part of this study,this paper provides details of two methods to quantify the CWR.One is diagnostic quantification(CWR-DQ)based on satellite observations,precipitation products,and atmospheric reanalysis data;and the other is numerical quantification(CWR-NQ)based on a cloud resolving model developed at the Chinese Academy of Meteorological Sciences(CAMS).The two methods are applied to quantify the CWR in April and August 2017 over North China,and the results are evaluated against all available observations.Main results are as follows.(1)For the CWR-DQ approach,reference cloud profiles are firstly derived based on the Cloud Sat/CALIPSO joint satellite observations for 2007–2010.The NCEP/NCAR reanalysis data in 2000–2017 are then employed to produce three-dimensional cloud fields.The budget/balance equations of atmospheric water substance are lastly used,together with precipitation observations,to retrieve CWR and related variables.It is found that the distribution and vertical structure of clouds obtained by the diagnostic method are consistent with observations.(2)For the CWR-NQ approach,it assumes that the cloud resolving model is able to describe the cloud microphysical processes completely and precisely,from which four-dimensional distributions of atmospheric water vapor,hydrometeors,and wind fields can be obtained.The data are then employed to quantify the CWR and related terms/quantities.After one-month continuous integration,the mass of atmospheric water substance becomes conserved,and the tempospatial distributions of water vapor,hydrometeors/cloud water,and precipitation are consistent with observations.(3)Diagnostic values of the difference in the transition between hydrometeors and water vapor(Cvh-Chv)and the surface evaporation(Es)are well consistent with their numerical values.(4)Correlation and bias analyses show that the diagnostic CWR contributors are well correlated with observations,and match their numerical counterparts as well,indicating that the CWR-NQ and CWR-DQ methods are reasonable.(5)Underestimation of water vapor converted from hydrometeors(Chv)is a shortcoming of the CWR-DQ method,which may be rectified by numerical quantification results or by use of advanced observations on higher spatiotemporal resolutions.
基金Supported by the National Key Research and Development Program of China(2016YFA0601701)National Natural Science Foundation of China(42075191)National High Technology Research and Development Program of China(2012AA120902).
文摘Based on the concept of cloud water resource(CWR)and the cloud microphysical scheme developed by the Chinese Academy of Meteorological Sciences(CAMS),a coupled mesoscale and cloud-resolving model system is developed in the study for CWR numerical quantification(CWR-NQ)in North China for 2017.The results show that(1)the model system is stable and capable for performing 1-yr continuous simulation with a water budget error of less than 0.2%,which indicates a good water balance.(2)Compared with the observational data,it is confirmed that the simulating capability of the CWR-NQ approach is decent for the spatial distribution of yearly cumulative precipitation,daily precipitation intensity,yearly average spatial distribution of water vapor.(3)Compared with the CWR diagnostic quantification(CWR-DQ),the results from the CWR-NQ differ mainly in cloud condensation and cloud evaporation.However,the deviation of the net condensation(condensation minus evaporation)between the two methods is less than 1%.For other composition variables,such as water vapor advection,surface evaporation,precipitation,cloud condensation,and total atmospheric water substances,the relative differences between the CWR-NQ and the CWR-DQ are less than 5%.(4)The spatiotemporal features of the CWR in North China are also studied.The positive correlation between water vapor convergence and precipitation on monthly and seasonal scales,and the lag of precipitation relative to water vapor convergence on hourly and daily scales are analyzed in detail,indicating the significance of the state term on hourly and daily scales.The effects of different spatial scales on the state term,advection term,source-sink term,and total amount are analyzed.It is shown that the advective term varies greatly at different spatiotemporal scales,which leads to differences at different spatiotemporal scales in CWR and related characteristic quantities.
基金This work was supported by the“Bairen Jihua”program of Chinese Academy of Sciences,the Chinese Academy of Sciences/State Administration of Foreign Experts Affairs(CAS/SAFEA)International Partnership Program for Creative Research Teams and Suzhou Bureau of Science and Technology.
文摘We report a novel method for rapid,colorimetric detection of a specific deoxyribonucleic acid(DNA)sequence by carrying out a polymerase chain reaction in the presence of gold nanoparticles functionalized with two primers.Extension of the primers when the target DNA is present as a template during the polymerase chain reaction process affords the complementary sequences on the gold nanoparticle surfaces and results in the formation of gold nanoparticle aggregates with a concomitant color change from red to pinkish/purple.This method provides a convenient and straightforward solution for ultrasensitive DNA detection without any further post-treatment of the polymerase chain reaction products being necessary,and is a promising tool for rapid disease diagnostics and gene sequencing.
基金National Key Research and Development Program of China(2017YFA0303700,2019YFA0308700)Innovation Program for Quantum Science and Technology(2021ZD0301500,2021ZD0301400)+2 种基金National Natural Science Foundation of China(11874212,11890704,61975077,62175102,62222507)Natural Science Foundation of Jiangsu Province(BK20212004)Program for Innovative Talents and Entrepreneurs in Jiangsu(JSSCTD202138)。
文摘High-dimensional entanglement is of great importance in quantum communications and can be realized by encoding information on multiple degrees of freedom(Do Fs)of the photons.Conventionally,the realization of such high-dimensional entanglement involves different combinations of bulky optical elements.In this work,we present the use of a single dielectric metasurface to generate high-dimensional entanglement by modulating multi-Do Fs of photons.By sending one of the polarization-entangled photons to interact with the metasurface,we encode path,spin angular momentum,and orbital angular momentum information to the original state.We achieve a four-qubit quantum state in the experiment.To verify it,we experimentally demonstrate the nonlocal correlations between the two photons by recording the correlated images,and we also perform a quantum state tomography measurement.This scheme can be applied to on-chip quantum state manipulation,which is promising in quantum communication with integrated components.
基金Supported by the National Key Research and Development Program of China(2016YFA0601701)Fengyun Application Pioneering Project(FY-APP-2021.0102)National High Technology Research and Development Program of China(2012AA120902).
文摘Identifying supercooled liquid water(SLW)in clouds is critical for weather modification,aviation safety,and atmospheric radiation calculations.Currently,aircraft identification in the SLW area mostly depends on emprical estimation of cloud particle number concentration(N_(c))in China,and scientific verification and quantitative identification criteria are urgently needed.In this study,the observations are from the Fast Cloud Droplets Probe,Rosemount ice detector(RICE),and Cloud Particle Imager(CP_(i))onboard a King Air aircraft during seven flights in 2018 and 2019 over central and eastern China.Based on this,the correlation among N_(c),the proportion of spherical particles(P_(s)),and the probability of icing(P_(i))in supercooled stratiform and cumulus-stratus clouds is statistically analyzed.Subsequently,this study proposes a method to identify SLW areas using N_(c) in combination with ambient temperature.The reliability of this method is evaluated through the true skill statistics(TSS)and threat score(TS)methods.Numerous airborne observations during the seven flights reveal a strong correlation among Nc,P_(s),and P_(i)at the temperature from 0 to−18°C.When Nc is greater than a certain threshold of 5 cm^(−3),there is always the SLW,i.e.,P_(i)and P_(s)are high.Evaluation results demonstrate that the TSS and TS values for Nc=5 cm^(−3)are higher than those for Nc<5 cm^(−3),and a larger Nc threshold(>5 cm^(−3))corresponds to a higher SLW identification hit rate and a higher SLW content.Therefore,Nc=5 cm^(−3)can be used as the minimum criterion for identifying the SLW in clouds at temperature lower than 0°C.The SLW identification method proposed in this study is especially helpful in common situations where aircraft are equipped with only Nc probes and without the CP_(i)and RICE.
基金Supported by the National Key Research and Development Program of China(2016YFA0601701)National High Technology Research and Development Program of China(2012AA120902)。
文摘By using the diagnostic quantification method for cloud water resource(CWR),the three-dimensional(3D)cloud fields of 1°×1°resolution during 2000-2019 in China are firstly obtained based on the NCEP reanalysis data and related satellite data.Then,combined with the Global Precipitation Climatology Project(GPCP)products,a 1°×1°gridded CWR dataset of China in recent 20 years is established.On this basis,the monthly and annual CWR and related variables in China and its six weather modification operation sub-regions are obtained,and the CWR characteristics in different regions are analyzed finally.The results show that in the past 20 years,the annual total amount of atmospheric hydrometeors(GM_(h))and water vapor(GM_(v))in the Chinese mainland are about 838.1 and 3835.9 mm,respectively.After deducting the annual mean precipitation of China(P_(s),661.7 mm),the annual CWR is about 176.4 mm.Among the six sub-regions,the southeast region has the largest amount of cloud condensation(C_(vh))and precipitation,leading to the largest GM_(h) and CWR there.In contrast,the annual P_(s),GM_(h),and CWR are all the least in the northwest region.Furthermore,the monthly and interannual variation trends of P_(s),C_(vh),and GM_(h) in different regions are identical,and the evolution characteristics of CWR are also consistent with the hydrometeor inflow(Q_(hi)).For the north,northwest,and northeast regions,in spring and autumn the precipitation efficiency of hydrometeors(PEh)is not high(20%-60%),the renewal time of hydrometeors(RT_(h))is relatively long(5-25 h),and GM_(h) is relatively high.Therefore,there is great potential for the development of CWR through artificial precipitation enhancement(APE).For the central region,spring,autumn,and winter are suitable seasons for CWR development.For the southeast and southwest regions,P_(s) and PE_(h) in summer are so high that the development of CWR should be avoided.For different spatial scales,there are significant differences in the characteristics of CWR.
基金Supported by the National Key Research and Development Program of China (2016YFA0601701)China Meteorological Administration Innovation and Development Project (CXFZ2021J039)Fengyun Satellite Application Pioneer Project (FY-APP-2021.0102)。
文摘To explore the key technologies of artificial weather modification for specific targets(e.g.,a stadium)and improve the efficiency of artificial rainfall modification for major events,this study conducts an artificial rainfall reduction experiment for the closing ceremony of Nanjing Youth Olympic Games on 28 August 2014.Satellite retrievals,radar observations,sounding data,and other sources of information as well as Cloud and Precipitation Accurate Analysis System(CPAS)are used in this study.The main conclusions are as follows.(1)On 28 August 2014,a large-scale cumulus cloud system with mixed-phase stratocumulus and stratus precipitation was observed.This system was influenced by the weak shear of a low-level trough and the precipitation was dominated by cold clouds with dry layers between clouds.Thereby,we adopted the crystal-priming over-catalytic hypothesis and conducted a rocket-catalytic rain abatement operation at a certain distance(100–25 km)from the stadium.Rocket shootings of different intensities were implemented for two echoes that affected the stadium successively(two rounds of 15 rocket shootings within15 min for an isolated weak echo IA;multiple rounds of 156 rocket shootings within 80 min for a strong echo IB).Amazingly,after the shootings with the catalysis in the air,reflectivity of the two echoes was reduced at all altitudes with the most significant reduction at the 2-km altitude,and the time needed for the obvious reduction was 40 min.The most obvious reduction of the two echoes then maintained for 60 and 53 min,respectively,and the operation time needed for the echo zone to recover after the stop of rocket shooting was 108 min for echo IA and 90 min for echo IB.The two echoes moving across the stadium during the time period of the closing ceremony(2000–2130 local time)were at their minimal strengths,with almost no echo over the target stadium.This demonstrates that the rocket shooting strategy of over-crystallization catalysis is effective,and the shooting site,time,and dose are reasonable.The following technical parameters were used during this experiment.At about 80–25 km away from the target stadium in the west,the rocket shooting lasted for 15–80 min and the doses were not less than 1 shot min~(-1)(1 shot min~(-1)for echo IA,2.25 shots min~(-1)for echo IB).The attenuation rate was 0.21 dBZ min~(-1)for the average 15 dBZ of echo IA.For the average 25 dBZ of echo IB,the attenuation rate was 0.27 dBZ min~(-1).The above technical settings helped achieve the goal of reducing rain over the stadium to almost zero for nearly 1-h period during the critical time of the event.
基金This work was supported by the Key Technology Improvement of Industrial Control System granted by the Ministry of Industry and Information.
文摘Emerging persistent memory technologies,like PCM and 3D XPoint,offer numerous advantages,such as higher density,larger capacity,and better energy efficiency,compared with the DRAM.However,they also have some drawbacks,e.g.,slower access speed,limited write endurance,and unbalanced read/write latency.Persistent memory technologies provide both great opportunities and challenges for operating systems.As a result,a large number of solutions have been proposed.With the increasing number and complexity of problems and approaches,we believe this is the right moment to investigate and analyze these works systematically.To this end,we perform a comprehensive and in-depth study on operating system support for persistent memory within three steps.First,we present an overview of how to build the operating system on persistent memory from three perspectives:system abstraction,crash consistency,and system reliability.Then,we classify the existing research works into three categories:storage stack,memory manager,and OS-bypassing library.For each category,we summarize the major research topics and discuss these topics deeply.Specifically,we present the challenges and opportunities in each topic,describe the contributions and limitations of proposed approaches,and compare these solutions in different dimensions.Finally,we also envision the future operating system based on this study.
基金Shanghai Municipal Science and Technology Major Project(2019SHZDZX01)Science and Technology Commission of Shanghai Municipality(20JC1416000,20QA1410400,22JC1402900)+3 种基金Excellent Postdoctoral Research Projects of Zhejiang Province(ZJ2021019)Natural Science Foundation of Zhejiang Province(LQ20F050005,LR22F050004)National Natural Science Foundation of China(62222514,61521005,61875217,61875218,61875223,61991442,62005249,91850208)State Key Program for Basic Research of China(2018YFA0306200).
文摘Topological insulators represent a new quantum phase of matter with spin-polarized surface states that are protected from backscattering, exhibiting electronic responses to light, such as topological quantum phase transitions. However, the effects of high-frequency driving topological intrinsic systems have remained largely unexplored challenges experimentally for high-sensitivity terahertz detection. In this study, by integrating Sb2Te3 topological insulators with subwavelength metal antennas through micro-nano processing, a high-frequency terahertz detector with high sensitivity is proposed. The enhanced response originates from the asymmetric scattering of the surface electrons in the Sb_(2)Te_(3) flakes induced by the terahertz wave. The device displays room-temperature photodetection with a responsivity of 192 mA/W and equivalent noise power of less than 0.35 nW/Hz^(1/2) in the frequency range from 0.02 to 0.3 THz. These results pave the way for the exploitation of topological insulators for high-frequency operation in real-time imaging within long-wavelength optoelectronics.
文摘Currently,security-critical server programs are well protected by various defense techniques,such as Address Space Layout Randomization(ASLR),eXecute Only Memory(XOM),and Data Execution Prevention(DEP),against modern code-reuse attacks like Return-oriented Programming(ROP)attacks.Moreover,in these victim programs,most syscall instructions lack the following ret instructions,which prevents attacks to stitch multiple system calls to implement advanced behaviors like launching a remote shell.Lacking this kind of gadget greatly constrains the capability of code-reuse attacks.This paper proposes a novel code-reuse attack method called Signal Enhanced Blind Return Oriented Programming(SeBROP)to address these challenges.Our SeBROP can initiate a successful exploit to server-side programs using only a stack overflow vulnerability.By leveraging a side-channel that exists in the victim program,we show how to find a variety of gadgets blindly without any pre-knowledges or reading/disassembling the code segment.Then,we propose a technique that exploits the current vulnerable signal checking mechanism to realize the execution flow control even when ret instructions are absent.Our technique can stitch a number of system calls without returns,which is more superior to conventional ROP attacks.Finally,the SeBROP attack precisely identifies many useful gadgets to constitute a Turing-complete set.SeBROP attack can defeat almost all state-of-the-art defense techniques.The SeBROP attack is compatible with both modern 64-bit and 32-bit systems.To validate its effectiveness,We craft three exploits of the SeBROP attack for three real-world applications,i.e.,32-bit Apache 1.3.49,32-bit ProFTPD 1.3.0,and 64-bit Nginx 1.4.0.Experimental results demonstrate that the SeBROP attack can successfully spawn a remote shell on Nginx,ProFTPD,and Apache with less than 8500/4300/2100 requests,respectively.
