Owing to the utilization of lithium metal as anode with the ultrahigh theoretical capacity density of 3860 mA h g^(-1)and oxide-based ceramic solid-state electrolytes(SE),e.g.,garnet-type Li7La_(3)Zr_(2)O_(12)(LLZO),a...Owing to the utilization of lithium metal as anode with the ultrahigh theoretical capacity density of 3860 mA h g^(-1)and oxide-based ceramic solid-state electrolytes(SE),e.g.,garnet-type Li7La_(3)Zr_(2)O_(12)(LLZO),all-state-state lithium metal batteries(ASLMBs)have been widely accepted as the promising alternatives for providing the satisfactory energy density and safety.However,its applications are still challenged by plenty of technical and scientific issues.In this contribution,the co-sintering temperature at 500℃is proved as a compromise method to fabricate the composite cathode with structural integrity and declined capacity fading of LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM).On the other hand,it tends to form weaker grain boundary(GB)inside polycrystalline LLZO at inadequate sintering temperature for LLZO,which can induce the intergranular failure of SE during the growth of Li filament inside the unavoidable defect on the interface of SE.Therefore,increasing the strength of GB,refining the grain to 0.4μm,and precluding the interfacial defect are suggested to postpone the electro-chemo-mechanical failure of SE with weak GB.Moreover,the advanced sintering techniques to lower the co-sintering temperature for both NCM-LLZO composite cathode and LLZO SE can be posted out to realize the viability of state-of-the-art ASLMBs with higher energy density as well as the guaranteed safety.展开更多
Most electronics such as sensors,actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy.Transferring the ceramic films from their growth substrates for assembling elec...Most electronics such as sensors,actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy.Transferring the ceramic films from their growth substrates for assembling electronic devices commonly requires chemical or physical etching,which comes at the sacrifice of the substrate materials,film cracks,and environmental contamination.Here,we introduce a van der Waals stripping method to fabricate large-area and freestanding piezoceramic thin films in a simple,green,and cost-effective manner.The introduction of the quasi van der Waals epitaxial platinum layer enables the capillary force of water to drive the separation process of the film and substrate interface.The fabricated lead-free film,Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)(BCZT),shows a high piezoelectric coefficient d_(33)=209±10 pm V−1 and outstanding flexibility of maximum strain 2%.The freestanding feature enables a wide application scenario,including micro energy harvesting,and covid-19 spike protein detection.We further conduct a life cycle analysis and quantify the low energy consumption and low pollution of the water-based stripping film method.展开更多
AIM To determine the role of hepatitis B virus X protein(HBx), HBx in regulating hepatic progenitor cell(HPC)-like features in hepatocellular carcinoma(HCC) and the underlying molecular mechanisms.METHODS We used a re...AIM To determine the role of hepatitis B virus X protein(HBx), HBx in regulating hepatic progenitor cell(HPC)-like features in hepatocellular carcinoma(HCC) and the underlying molecular mechanisms.METHODS We used a retrovirus vector to introduce wild type HBx or empty vector into Hep G2 cells. We then used these cells to analyze cell proliferation, senescence, transformation, and stem-like features. Gene expression profiling was carried out on Affymetrix GeneC hip Human U133A2.0 ver.2 arrays according to the manufacturer's protocol. Unsupervised hierarchical clustering analysis and Class Comparison analysis were performed by BRB-Array Tools software Version 4.2.2. A total of 238 hepatitis B virus(HBV)-related HCC patients' array data were used for analyzing clinical features.RESULTS The histone demethylase KDM5 B was significantlyhighly expressed in HBV-related HCC cases(P < 0.01). In HBV proteins, only HBx up-regulated KDM5 B by activating c-myc. Hepatic stem cell(Hp SC) markers(EpC AM, AFP, PROM1, and NANOG) were significantly highly expressed in KDM5B-high HCC cases(P < 0.01). KDM5 B played an important role in maintaining HpS Clike features and was associated with a poor prognosis. Moreover, inhibition of KDM5 B suppressed spheroid formation and cell invasion in vitro.CONCLUSION HBx activates the histone demethylase KDM5 B and induces HPC-like features in HCC. Histone demethylases KDM5 B may be an important therapeutic target against HBV-related HCC cases.展开更多
Determining an optimal sample size is a key step in designing field surveys,and is particularly important for detecting the spatial pattern of highly variable properties such as soil organic carbon(SOC).Based on 550 s...Determining an optimal sample size is a key step in designing field surveys,and is particularly important for detecting the spatial pattern of highly variable properties such as soil organic carbon(SOC).Based on 550 soil sampling points in the nearsurface layer(0 to 20 cm)in a representative region of northern China's agro-pastoral ecotone,we studied effects of four interpolation methods such as ordinary kriging(OK),universal kriging(UK),inverse distance weighting(IDW)and radial basis function(RBF)and random subsampling(50,100,200,300,400,and 500)on the prediction accuracy of SOC estimation.When the Shannon's Diversity Index(SHDI)and Shannon's Evenness Index(SHEI)was 2.01 and 0.67,the OK method appeared to be a superior method,which had the smallest root mean square error(RMSE)and the mean error(ME)nearest to zero.On the contrary,the UK method performed poorly for the interpolation of SOC in the present study.The sample size of 200 had the most accurate prediction;50 sampling points produced the worst prediction accuracy.Thus,we used 200 samples to estimate the study area's soil organic carbon density(SOCD)by the OK method.The total SOC storage to a depth of 20 cm in the study area was 117.94 Mt,and its mean SOCD was 2.40 kg/m2.The SOCD kg/(C⋅m2)of different land use types were in the following order:woodland(3.29)>grassland(2.35)>cropland(2.19)>sandy land(1.55).展开更多
Multi-user file-sharing plays an important role in the cloud storage.It allows different users to share files via the cloud.However,it usually faces many security issues because the cloud is usually public and semi-tr...Multi-user file-sharing plays an important role in the cloud storage.It allows different users to share files via the cloud.However,it usually faces many security issues because the cloud is usually public and semi-trusted.To overcome these issues,we propose multi-user file-sharing systems(MFS)in this paper.According to the date sources,we propose two frameworks of MFS based on the framework of proxy re-encryption(PRE),unique source(uni-source)MFS and multi-source MFS.We formalize the security models,which contain ciphertext security,secret key security and master secret security.With the frameworks,we propose two secure and efficient MFS schemes based on LWE,the uni-source MFS UM and the multi-source MFS MM.We prove that UM is secret key and ciphertext security,and MM is secret key,master secret and ciphertext security with the hardness assumptions of LWE and SIS.Furtherly,we prove they have some useful properties,such as non-interactive and anonymous.展开更多
In this work,a hybrid integrated optical transmitter module was designed and fabricated.A proton-exchanged Mach–Zehnder lithium niobate(LiNbO_(3))modulator chip was chosen to enhance the output extinction ratio.A fib...In this work,a hybrid integrated optical transmitter module was designed and fabricated.A proton-exchanged Mach–Zehnder lithium niobate(LiNbO_(3))modulator chip was chosen to enhance the output extinction ratio.A fiber was used to adjust the rotation of the polarization direction caused by the optical isolator.The whole optical path structure,including the laser chip,lens,fiber,and modulator chip,was simulated to achieve high optical output efficiency.After a series of process improvements,a module with an output extinction ratio of 34 dB and a bandwidth of 20.5 GHz(from 2 GHz)was obtained.The optical output efficiency of the whole module reached approximately 21%.The link performance of the module was also measured.展开更多
Shear stress-displacement relationship model of soil is very important to predict the tractive performance of tracked vehicle. Most shear stress-displacement models were proposed for terrestrial field.However,they are...Shear stress-displacement relationship model of soil is very important to predict the tractive performance of tracked vehicle. Most shear stress-displacement models were proposed for terrestrial field.However,they are not suit for soft seafloor with flow surface and high water content. Based on comprehensive analysis of seafloor soil shear deformation and track segment shear tests,a new empirical model of shear stressdisplacement relationship for saturated soft-plastic soil(SSP model) was proposed. To validate the SSP model and evaluate potential tractive force of self-propelled seafloor trencher,a test platform,where track segment shear test and drawbar pull test can be performed in seafloor soil substitute(bentonite water mixture),was built. Series of shear tests were carried out. Test results show that the SSP model can describe the mechanical behavior of track segment in seafloor soil substitute with good approximation. Through analyzing the main external forces,including environmental loads from seafloor soil and sea current applied to seafloor tracked trencher during the trenching process in a straight line,drawbar pull analysis model was deduced with the SSP model. A scale test model of seafloor tracked trencher was built,and the verification tests for drawbar pull analysis model were designed and carried out. Results of verification tests indicate that the drawbar pull analysis model was feasible and effective. The drawbar pull tests also indicated that the SSP model is valid from another side.展开更多
Recently,an increasing number of works start investigating the combination of fog computing and electronic health(ehealth)applications.However,there are still numerous unresolved issues worth to be explored.For instan...Recently,an increasing number of works start investigating the combination of fog computing and electronic health(ehealth)applications.However,there are still numerous unresolved issues worth to be explored.For instance,there is a lack of investigation on the disease prediction in fog environment and only limited studies show,how the Quality of Service(QoS)levels of fog services and the data stream mining techniques influence each other to improve the disease prediction performance(e.g.,accuracy and time efficiency).To address these issues,we propose a fog-based framework for disease prediction based on Medical sensor data streams,named FogMed.This framework aims to improve the disease prediction accuracy by achieving two objectives:QoS guarantee of fog services and anomaly prediction of Medical data streams.We build a virtual FogMed environment and conduct comprehensive experiments on the public ECG dataset to validate the performance of FogMed.The experiment results show that it performs better than the cloud computing model for processing tasks with different complexities in terms of time efficiency.展开更多
In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller...In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller to stabilize the head of the underwater snake-like robot. The advantage of the CPG-based control scheme with head-controller is that the head of the underwater snake-like robot is direct to the target orientation during swimming. The relation between CPG parameters and orientation stability of head is discussed.The adaptation of the proposed method to environment changes is tested. The influences of CPG parameters and hydrodynamic forces on the orientation offset of head are investigated. The target orientation( the input of headcontroller) with an experimental optimization is calculated through a convenient method. To prove the feasibility of the proposed methodology,the different swimming modes have been implemented in our simulation platform.The results show that the oscillation of head's orientation is inhibited effectively,and the proposed method has strong adaptation to environment and CPG parameters changes.展开更多
Wastewater management and energy/resource recycling have been extensively investigated via photo(electro)catalysis.Although both operation processes are driven effectively by the same interfacial charge,each system is...Wastewater management and energy/resource recycling have been extensively investigated via photo(electro)catalysis.Although both operation processes are driven effectively by the same interfacial charge,each system is practiced separately since they require very different reaction conditions.In this review,we showcase the recent advancements in photo(electro)catalytic process that enables the wastewater treatment and simultaneous energy/resource recovery(WT-ERR).Various literatures based on photo(electro)catalysis for wastewater treatment coupled with CO_(2)conversion,H_(2)production and heavy metal recovery are summarized.Besides,the fundamentals of photo(electro)catalysis and the influencing factors in such synergistic process are also presented.The essential feature of the catalysis lies in effectively utilizing hole oxidation for pollutant degradation and electron reduction for energy/resource recovery.Although in its infancy,the reviewed technology provides new avenue for developing next-generation wastewater treatment process.Moreover,we expect that this review can stimulate intensive researches to rationally design photo(electro)catalytic systems for environmental remediation accompanied with energy and resource recovery.展开更多
Although natural variations in rice flavonoids exist, and biochemical characterization of a few flavonoid glycosyltransferases has been reported, few studies focused on natural variations in tricin-lignan-glycosides a...Although natural variations in rice flavonoids exist, and biochemical characterization of a few flavonoid glycosyltransferases has been reported, few studies focused on natural variations in tricin-lignan-glycosides and their underlying genetic basis. In this study, we carried out metabolic profiling of tricin-lignan-glycosides and identified a major quantitative gene annotated as a UDPdependent glycosyltransferase OsUGT706C2 by metabolite-based genome-wide association analysis. The putative flavonoid glycosyltransferase OsUGT706C2 was characterized as a flavonoid 7-O-glycosyltransferas in vitro and in vivo. Although the in vitro enzyme activity of OsUGT706C2 was similar to that of OsUGT706D1, the expression pattern and induced expression profile of OsUGT706C2 were very different from those of OsUGT706D1. Besides, OsUGT706C2 was specifically induced by UV-B. Constitutive expression of OsUGT706C2 in rice may modulate phenylpropanoid metabolism at both the transcript and metabolite levels. Furthermore, overexpressing OsUGT706C2 can enhance UV-B tolerance by promoting ROS scavenging in rice. Our findings might make it possible to use the glycosyltransferase OsUGT706C2 for crop improvement with respect to UVB adaptation and/or flavonoid accumulation, which may contribute to stable yield.展开更多
Microstructure degradation and stress-induced transformation of a high Nb-containing TiAl alloy with nearly lamellar microstructure during creep were investigated.Tensile creep experiments were performed at 800,850 an...Microstructure degradation and stress-induced transformation of a high Nb-containing TiAl alloy with nearly lamellar microstructure during creep were investigated.Tensile creep experiments were performed at 800,850 and 900℃ under 150 MPa in air.Microstructures before and after creep tests were examined using scanning and transmission electron microscopy(SEM and TEM).Dislocations within the lamellar structure andβo(ω)region and twin intersection in massiveγgrains were investigated.Dislocation sliding played a critical role in the deformation ofωo phase,which preferentially occurred on the(0002)ωo plane.Possible deformation mechanisms were revealed.A stress-inducedγ→α2 phase transformation took place during the creep test at 850 and 900℃.α2 lamella could directly decompose into theωo phase at 850℃.The instability of high-temperature microstructure can weaken the creep resistance and promote the plastic deformation of the lamellar matrix,thus could be detrimental to the creep properties.The correlations between creep properties and microstructure instability were discussed.展开更多
Efficient reconciliation is a crucial step in continuous variable quantum key distribution. The progressive-edge-growth(PEG) algorithm is an efficient method to construct relatively short block length low-density pari...Efficient reconciliation is a crucial step in continuous variable quantum key distribution. The progressive-edge-growth(PEG) algorithm is an efficient method to construct relatively short block length low-density parity-check(LDPC) codes. The qua-sicyclic construction method can extend short block length codes and further eliminate the shortest cycle. In this paper, by combining the PEG algorithm and quasi-cyclic construction method, we design long block length irregular LDPC codes with high error-correcting capacity. Based on these LDPC codes, we achieve high-efficiency Gaussian key reconciliation with slice recon-ciliation based on multilevel coding/multistage decoding with an efficiency of 93.7%.展开更多
The active eutectoid decomposition and its morphological evolution during slow cooling and isothermal holding were investigated in a Ru-containing Ti Al alloy. The fine τ 1/γ active eutectoid nodules precipitated at...The active eutectoid decomposition and its morphological evolution during slow cooling and isothermal holding were investigated in a Ru-containing Ti Al alloy. The fine τ 1/γ active eutectoid nodules precipitated at α grain boundary and interior during water quenching. The active eutectoid microstructure evolved from sheaf-like, granular to bulky net-like sluggish eutectoid morphology gradually with the decrease in quenching/holding temperatures. The active eutectoid reaction occurs from 1220 to 1290 ℃, while the beginning temperature of sluggish eutectoid locates at 1305 ± 5 ℃. The combination of the intact τ_(1) phase and immature nano-sized γ laths suggests a short incubation period of τ_(1) phase in the active type. Furtherly, the semiquantitative estimation shows that the growth velocity of active eutectoid is about ninety times higher than sluggish type. In addition, a representative feature of γ phase abruptly ripening along {111} crystallographic plane was also observed in the active eutectoid.展开更多
The failure to achieve minimum design overlap between secant piles compromises the ability of a structure to perform as designed,resulting in water leakage or even ground collapse.To establish a more realistic simulat...The failure to achieve minimum design overlap between secant piles compromises the ability of a structure to perform as designed,resulting in water leakage or even ground collapse.To establish a more realistic simulation and provide guidelines for designing a safe and cost-effective secant-pile wall,a three-dimensional model of a secant pile,considering the geometric imperfections of the diameter and direction of the borehole,is introduced.An ultrasonic cross-hole test was performed during the construction of secant piles in a launching shaft in Beijing,China.Based on the test results,the statistical characteristics of the pile diameters and orientation parameters were obtained.By taking the pile diameter D,inclination angleβ,and azimuth angleαas random variables,Monte Carlo simulations were performed to discuss the influence of different design parameters on the probability density functions of the overlap of secant piles.The obtained results show that the randomness of the inclination angle and pile diameter can be well described by a normal distribution,whereas the azimuth angle is more consistent with a uniform distribution.The integrity of the secant-pile wall can be overestimated without considering the uncertainty of geometric imperfections.The failure of the secant-pile wall increases substantially with increasing spatial variability in drilling inclination and diameter.A design flowchart for pile spacing under the target safety level is proposed to help engineers design a safe and economical pile wall.展开更多
基金the National Natural Science Foundation of China(12102328)for supporting this work。
文摘Owing to the utilization of lithium metal as anode with the ultrahigh theoretical capacity density of 3860 mA h g^(-1)and oxide-based ceramic solid-state electrolytes(SE),e.g.,garnet-type Li7La_(3)Zr_(2)O_(12)(LLZO),all-state-state lithium metal batteries(ASLMBs)have been widely accepted as the promising alternatives for providing the satisfactory energy density and safety.However,its applications are still challenged by plenty of technical and scientific issues.In this contribution,the co-sintering temperature at 500℃is proved as a compromise method to fabricate the composite cathode with structural integrity and declined capacity fading of LiNi_(0.5)Co_(0.2)Mn_(0.3)O_(2)(NCM).On the other hand,it tends to form weaker grain boundary(GB)inside polycrystalline LLZO at inadequate sintering temperature for LLZO,which can induce the intergranular failure of SE during the growth of Li filament inside the unavoidable defect on the interface of SE.Therefore,increasing the strength of GB,refining the grain to 0.4μm,and precluding the interfacial defect are suggested to postpone the electro-chemo-mechanical failure of SE with weak GB.Moreover,the advanced sintering techniques to lower the co-sintering temperature for both NCM-LLZO composite cathode and LLZO SE can be posted out to realize the viability of state-of-the-art ASLMBs with higher energy density as well as the guaranteed safety.
基金supported by General Research Grant(Project No.11212021,No.11210822)Early Career Scheme(Project No.CityU 21210619)from the Research Grants Council of the Hong Kong Special Administrative Regionthe Innovation and Technology Fund(ITS/065/20,GHP/096/19SZ)from the Innovation and Technology Commission of the Hong Kong Special Administrative Region.
文摘Most electronics such as sensors,actuators and energy harvesters need piezoceramic films to interconvert mechanical and electrical energy.Transferring the ceramic films from their growth substrates for assembling electronic devices commonly requires chemical or physical etching,which comes at the sacrifice of the substrate materials,film cracks,and environmental contamination.Here,we introduce a van der Waals stripping method to fabricate large-area and freestanding piezoceramic thin films in a simple,green,and cost-effective manner.The introduction of the quasi van der Waals epitaxial platinum layer enables the capillary force of water to drive the separation process of the film and substrate interface.The fabricated lead-free film,Ba_(0.85)Ca_(0.15)Zr_(0.1)Ti_(0.9)O_(3)(BCZT),shows a high piezoelectric coefficient d_(33)=209±10 pm V−1 and outstanding flexibility of maximum strain 2%.The freestanding feature enables a wide application scenario,including micro energy harvesting,and covid-19 spike protein detection.We further conduct a life cycle analysis and quantify the low energy consumption and low pollution of the water-based stripping film method.
基金Supported by Grant-in-Aid for Scientific Research(KAKENHI)(C),No.15K08992(to Oishi N)Core-to-Core Program,B.Asia-Africa Science Platforms,the Japan Society for the Promotion of Science(to Kaneko S)
文摘AIM To determine the role of hepatitis B virus X protein(HBx), HBx in regulating hepatic progenitor cell(HPC)-like features in hepatocellular carcinoma(HCC) and the underlying molecular mechanisms.METHODS We used a retrovirus vector to introduce wild type HBx or empty vector into Hep G2 cells. We then used these cells to analyze cell proliferation, senescence, transformation, and stem-like features. Gene expression profiling was carried out on Affymetrix GeneC hip Human U133A2.0 ver.2 arrays according to the manufacturer's protocol. Unsupervised hierarchical clustering analysis and Class Comparison analysis were performed by BRB-Array Tools software Version 4.2.2. A total of 238 hepatitis B virus(HBV)-related HCC patients' array data were used for analyzing clinical features.RESULTS The histone demethylase KDM5 B was significantlyhighly expressed in HBV-related HCC cases(P < 0.01). In HBV proteins, only HBx up-regulated KDM5 B by activating c-myc. Hepatic stem cell(Hp SC) markers(EpC AM, AFP, PROM1, and NANOG) were significantly highly expressed in KDM5B-high HCC cases(P < 0.01). KDM5 B played an important role in maintaining HpS Clike features and was associated with a poor prognosis. Moreover, inhibition of KDM5 B suppressed spheroid formation and cell invasion in vitro.CONCLUSION HBx activates the histone demethylase KDM5 B and induces HPC-like features in HCC. Histone demethylases KDM5 B may be an important therapeutic target against HBV-related HCC cases.
基金This research was supported by the National Key R and D Program of China(2016YFC0500901 and 2016YFC0500907)the National Natural Science Foundation of China(Grant Nos.31971466 and 41807525)the One Hundred Person Project of the Chinese Academy of Sciences(Y551821).
文摘Determining an optimal sample size is a key step in designing field surveys,and is particularly important for detecting the spatial pattern of highly variable properties such as soil organic carbon(SOC).Based on 550 soil sampling points in the nearsurface layer(0 to 20 cm)in a representative region of northern China's agro-pastoral ecotone,we studied effects of four interpolation methods such as ordinary kriging(OK),universal kriging(UK),inverse distance weighting(IDW)and radial basis function(RBF)and random subsampling(50,100,200,300,400,and 500)on the prediction accuracy of SOC estimation.When the Shannon's Diversity Index(SHDI)and Shannon's Evenness Index(SHEI)was 2.01 and 0.67,the OK method appeared to be a superior method,which had the smallest root mean square error(RMSE)and the mean error(ME)nearest to zero.On the contrary,the UK method performed poorly for the interpolation of SOC in the present study.The sample size of 200 had the most accurate prediction;50 sampling points produced the worst prediction accuracy.Thus,we used 200 samples to estimate the study area's soil organic carbon density(SOCD)by the OK method.The total SOC storage to a depth of 20 cm in the study area was 117.94 Mt,and its mean SOCD was 2.40 kg/m2.The SOCD kg/(C⋅m2)of different land use types were in the following order:woodland(3.29)>grassland(2.35)>cropland(2.19)>sandy land(1.55).
基金supported by Purple Mountain Laboratories,Frontiers Science Center for Mobile Information Communication and Security,and Science and technology project of Jiangsu province(No.BE2019019)。
文摘Multi-user file-sharing plays an important role in the cloud storage.It allows different users to share files via the cloud.However,it usually faces many security issues because the cloud is usually public and semi-trusted.To overcome these issues,we propose multi-user file-sharing systems(MFS)in this paper.According to the date sources,we propose two frameworks of MFS based on the framework of proxy re-encryption(PRE),unique source(uni-source)MFS and multi-source MFS.We formalize the security models,which contain ciphertext security,secret key security and master secret security.With the frameworks,we propose two secure and efficient MFS schemes based on LWE,the uni-source MFS UM and the multi-source MFS MM.We prove that UM is secret key and ciphertext security,and MM is secret key,master secret and ciphertext security with the hardness assumptions of LWE and SIS.Furtherly,we prove they have some useful properties,such as non-interactive and anonymous.
基金This work was supported by National Key Research and Development Program of China(2018YFB2201101)the Strategic Priority Research Program of Chinese Academy of Sciences,Grant No.XDB43000000Beijing Municipal Science&Technology Commission,Administrative Commission of Zhongguancun Science Park No.Z201100004020004。
文摘In this work,a hybrid integrated optical transmitter module was designed and fabricated.A proton-exchanged Mach–Zehnder lithium niobate(LiNbO_(3))modulator chip was chosen to enhance the output extinction ratio.A fiber was used to adjust the rotation of the polarization direction caused by the optical isolator.The whole optical path structure,including the laser chip,lens,fiber,and modulator chip,was simulated to achieve high optical output efficiency.After a series of process improvements,a module with an output extinction ratio of 34 dB and a bandwidth of 20.5 GHz(from 2 GHz)was obtained.The optical output efficiency of the whole module reached approximately 21%.The link performance of the module was also measured.
文摘Shear stress-displacement relationship model of soil is very important to predict the tractive performance of tracked vehicle. Most shear stress-displacement models were proposed for terrestrial field.However,they are not suit for soft seafloor with flow surface and high water content. Based on comprehensive analysis of seafloor soil shear deformation and track segment shear tests,a new empirical model of shear stressdisplacement relationship for saturated soft-plastic soil(SSP model) was proposed. To validate the SSP model and evaluate potential tractive force of self-propelled seafloor trencher,a test platform,where track segment shear test and drawbar pull test can be performed in seafloor soil substitute(bentonite water mixture),was built. Series of shear tests were carried out. Test results show that the SSP model can describe the mechanical behavior of track segment in seafloor soil substitute with good approximation. Through analyzing the main external forces,including environmental loads from seafloor soil and sea current applied to seafloor tracked trencher during the trenching process in a straight line,drawbar pull analysis model was deduced with the SSP model. A scale test model of seafloor tracked trencher was built,and the verification tests for drawbar pull analysis model were designed and carried out. Results of verification tests indicate that the drawbar pull analysis model was feasible and effective. The drawbar pull tests also indicated that the SSP model is valid from another side.
基金This work is supported by NUIST Students’Platform for Innovation and Entrepreneurship Training Program,the National Natural Science Foundation of China(Grants No61702274)the Natural Science Foundation of Jiangsu Province(Grants No BK20170958),and PAPD.
文摘Recently,an increasing number of works start investigating the combination of fog computing and electronic health(ehealth)applications.However,there are still numerous unresolved issues worth to be explored.For instance,there is a lack of investigation on the disease prediction in fog environment and only limited studies show,how the Quality of Service(QoS)levels of fog services and the data stream mining techniques influence each other to improve the disease prediction performance(e.g.,accuracy and time efficiency).To address these issues,we propose a fog-based framework for disease prediction based on Medical sensor data streams,named FogMed.This framework aims to improve the disease prediction accuracy by achieving two objectives:QoS guarantee of fog services and anomaly prediction of Medical data streams.We build a virtual FogMed environment and conduct comprehensive experiments on the public ECG dataset to validate the performance of FogMed.The experiment results show that it performs better than the cloud computing model for processing tasks with different complexities in terms of time efficiency.
基金Sponsored by the National Nature Science Foundation of China(Grant No.51009091)the Special Research Fund for the Doctoral Program of Higher Education(Grant No.20100073120016)
文摘In prior research,the orientation of head of the snake-like robot is changed according to the sinusoidal wave. To solve this problem,we propose Central Pattern Generator( CPG)-based control scheme with head-controller to stabilize the head of the underwater snake-like robot. The advantage of the CPG-based control scheme with head-controller is that the head of the underwater snake-like robot is direct to the target orientation during swimming. The relation between CPG parameters and orientation stability of head is discussed.The adaptation of the proposed method to environment changes is tested. The influences of CPG parameters and hydrodynamic forces on the orientation offset of head are investigated. The target orientation( the input of headcontroller) with an experimental optimization is calculated through a convenient method. To prove the feasibility of the proposed methodology,the different swimming modes have been implemented in our simulation platform.The results show that the oscillation of head's orientation is inhibited effectively,and the proposed method has strong adaptation to environment and CPG parameters changes.
基金financially supported by the National Natural Science Foundation of China(Nos.52000097,51878325,51868050 and 51938007)the Natural Science Foundation of Jiangxi Province(Nos.20192BAB213011 and 20192ACBL21046)+1 种基金the Ph.D.research startup foundation of Nanchang Hangkong University(No.EA201802367)the Open Project Program of the State Key Laboratory of Photocatalysis on Energy and Environment(No.SKLPEE-KF202106),Fuzhou University。
文摘Wastewater management and energy/resource recycling have been extensively investigated via photo(electro)catalysis.Although both operation processes are driven effectively by the same interfacial charge,each system is practiced separately since they require very different reaction conditions.In this review,we showcase the recent advancements in photo(electro)catalytic process that enables the wastewater treatment and simultaneous energy/resource recovery(WT-ERR).Various literatures based on photo(electro)catalysis for wastewater treatment coupled with CO_(2)conversion,H_(2)production and heavy metal recovery are summarized.Besides,the fundamentals of photo(electro)catalysis and the influencing factors in such synergistic process are also presented.The essential feature of the catalysis lies in effectively utilizing hole oxidation for pollutant degradation and electron reduction for energy/resource recovery.Although in its infancy,the reviewed technology provides new avenue for developing next-generation wastewater treatment process.Moreover,we expect that this review can stimulate intensive researches to rationally design photo(electro)catalytic systems for environmental remediation accompanied with energy and resource recovery.
基金supported by the Foundation for the Major Science and Technology Program of Ningxia Hui Autonomous Region (2016BZ06)the State Key Program of National Natural Science Foundation of China (31530052)+2 种基金the National Science Fund for Distinguished Young Scholars (31625021)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (31821005)the Hainan University Startup Fund (KYQD(ZR)1866) to JL。
文摘Although natural variations in rice flavonoids exist, and biochemical characterization of a few flavonoid glycosyltransferases has been reported, few studies focused on natural variations in tricin-lignan-glycosides and their underlying genetic basis. In this study, we carried out metabolic profiling of tricin-lignan-glycosides and identified a major quantitative gene annotated as a UDPdependent glycosyltransferase OsUGT706C2 by metabolite-based genome-wide association analysis. The putative flavonoid glycosyltransferase OsUGT706C2 was characterized as a flavonoid 7-O-glycosyltransferas in vitro and in vivo. Although the in vitro enzyme activity of OsUGT706C2 was similar to that of OsUGT706D1, the expression pattern and induced expression profile of OsUGT706C2 were very different from those of OsUGT706D1. Besides, OsUGT706C2 was specifically induced by UV-B. Constitutive expression of OsUGT706C2 in rice may modulate phenylpropanoid metabolism at both the transcript and metabolite levels. Furthermore, overexpressing OsUGT706C2 can enhance UV-B tolerance by promoting ROS scavenging in rice. Our findings might make it possible to use the glycosyltransferase OsUGT706C2 for crop improvement with respect to UVB adaptation and/or flavonoid accumulation, which may contribute to stable yield.
基金financially supported by the National Natural Science Foundation of China(Nos.51774238 and51971176)the 2018 Joint Foundation of Ministry of Education for Equipment Pre-research(No.6141A020332)+1 种基金the State Key Laboratory for Advanced Metal and Materials Foundation(No.2014-ZD06)the Open Project of Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education,Lanzhou University(No.LZUMMM2020008)。
文摘Microstructure degradation and stress-induced transformation of a high Nb-containing TiAl alloy with nearly lamellar microstructure during creep were investigated.Tensile creep experiments were performed at 800,850 and 900℃ under 150 MPa in air.Microstructures before and after creep tests were examined using scanning and transmission electron microscopy(SEM and TEM).Dislocations within the lamellar structure andβo(ω)region and twin intersection in massiveγgrains were investigated.Dislocation sliding played a critical role in the deformation ofωo phase,which preferentially occurred on the(0002)ωo plane.Possible deformation mechanisms were revealed.A stress-inducedγ→α2 phase transformation took place during the creep test at 850 and 900℃.α2 lamella could directly decompose into theωo phase at 850℃.The instability of high-temperature microstructure can weaken the creep resistance and promote the plastic deformation of the lamellar matrix,thus could be detrimental to the creep properties.The correlations between creep properties and microstructure instability were discussed.
基金supported by the National Natural Science Foundation of China(Grant No.61378010)the Natural Science Foundation of Shanxi Province(Grant No.2014011007-1)
文摘Efficient reconciliation is a crucial step in continuous variable quantum key distribution. The progressive-edge-growth(PEG) algorithm is an efficient method to construct relatively short block length low-density parity-check(LDPC) codes. The qua-sicyclic construction method can extend short block length codes and further eliminate the shortest cycle. In this paper, by combining the PEG algorithm and quasi-cyclic construction method, we design long block length irregular LDPC codes with high error-correcting capacity. Based on these LDPC codes, we achieve high-efficiency Gaussian key reconciliation with slice recon-ciliation based on multilevel coding/multistage decoding with an efficiency of 93.7%.
基金financially supported by the National Natural Science Foundation of China(No.51774238)the 2018 joint Foundation of Ministry of Education for Equipment Preresearch(No.6141A020332)。
文摘The active eutectoid decomposition and its morphological evolution during slow cooling and isothermal holding were investigated in a Ru-containing Ti Al alloy. The fine τ 1/γ active eutectoid nodules precipitated at α grain boundary and interior during water quenching. The active eutectoid microstructure evolved from sheaf-like, granular to bulky net-like sluggish eutectoid morphology gradually with the decrease in quenching/holding temperatures. The active eutectoid reaction occurs from 1220 to 1290 ℃, while the beginning temperature of sluggish eutectoid locates at 1305 ± 5 ℃. The combination of the intact τ_(1) phase and immature nano-sized γ laths suggests a short incubation period of τ_(1) phase in the active type. Furtherly, the semiquantitative estimation shows that the growth velocity of active eutectoid is about ninety times higher than sluggish type. In addition, a representative feature of γ phase abruptly ripening along {111} crystallographic plane was also observed in the active eutectoid.
基金the National Natural Science Foundation of China(Grant Nos.51978040 and 51378054)the National Basic Research Program of China(973 program,No.2015CB057800)for supporting this research.
文摘The failure to achieve minimum design overlap between secant piles compromises the ability of a structure to perform as designed,resulting in water leakage or even ground collapse.To establish a more realistic simulation and provide guidelines for designing a safe and cost-effective secant-pile wall,a three-dimensional model of a secant pile,considering the geometric imperfections of the diameter and direction of the borehole,is introduced.An ultrasonic cross-hole test was performed during the construction of secant piles in a launching shaft in Beijing,China.Based on the test results,the statistical characteristics of the pile diameters and orientation parameters were obtained.By taking the pile diameter D,inclination angleβ,and azimuth angleαas random variables,Monte Carlo simulations were performed to discuss the influence of different design parameters on the probability density functions of the overlap of secant piles.The obtained results show that the randomness of the inclination angle and pile diameter can be well described by a normal distribution,whereas the azimuth angle is more consistent with a uniform distribution.The integrity of the secant-pile wall can be overestimated without considering the uncertainty of geometric imperfections.The failure of the secant-pile wall increases substantially with increasing spatial variability in drilling inclination and diameter.A design flowchart for pile spacing under the target safety level is proposed to help engineers design a safe and economical pile wall.
