It is well known that coarse-grained super-elastic NiTi shape memory alloys(SMAs)exhibit localized rather than homogeneous martensite transformation(MT),which,however,can be strongly influenced by either internal size...It is well known that coarse-grained super-elastic NiTi shape memory alloys(SMAs)exhibit localized rather than homogeneous martensite transformation(MT),which,however,can be strongly influenced by either internal size(grain size,GS)or the external size(geometric size).The coupled effect of GS and geometric size on the functional properties has not been clearly understood yet.In this work,the super-elasticity,one-way,and stress-assisted two-way shape memory effects of the polycrystalline NiTi SMAs with different aspect ratios(length/width for the gauge section)and different GSs are investigated based on the phase field method.The coupled effect of the aspect ratio and GS on the functional properties is adequately revealed.The simulated results indicate that when the aspect ratio is lower than about 4:1,the stress biaxiality and stress heterogeneity in the gauge section of the sample become more and more obvious with decreasing the aspect ratio,which can significantly influence the microstructure evolution in the process involving external stress.Therefore,the corresponding functional property is strongly dependent on the aspect ratio.With decreasing the GS and the aspect ratio(to be lower than 4:1),both the aspect ratio and GS can affect the MT or martensite reorientation in each grain and the interaction among grains.Thus,due to the strong internal constraint(i.e.,the constraint of grain boundary)and the external constraint(i.e.,the constraint of geometric boundary),the capabilities of the functional properties of NiTi SMAs are gradually weakened and highly dependent on these two factors.展开更多
In ball milling,the process parameters are decisive in influencing the quality and performance of the final ball-milled product,and crucial but often neglected is the ratio of the grinding balls in terms of their size...In ball milling,the process parameters are decisive in influencing the quality and performance of the final ball-milled product,and crucial but often neglected is the ratio of the grinding balls in terms of their size.Here,for a given number of large grinding balls,the ratio of large to small ones is set to 1:2,1:3,1:4,and 1:5 by altering the number of small ones,and how this affects the morphology,structure,and electrochemical properties of ball-milled graphene nanosheets is investigated.The results show that changing the ball ratio causes distinct changes in the morphology,structure,and properties of the graphene nanosheets.Increasing the number of small(6 mm)grinding balls decreases the nanosheet grain size monotonically;meanwhile,the crystal plane spacing,defect density,and specific surface area increase and then decrease,but the graphitization degree decreases and then increases.Ball-milled samples are then used as anodes for lithium-ion batteries,and both the specific capacity and rate capability exhibit the same trend of increase and then decrease.The ball ratio of 1:3 gives the best electrochemical performance,i.e.,a reversible specific capacity of 262.09 mA·h/g at a current density of 100 mA/g,and even after 2000 cycles at 2000 mA/g,the reversible specific capacity is 87.4%of the optimal value.展开更多
The mineralogy and texture of granite have been found to have a pronounced effect on its mechanical behavior.However,the precise manner in which the texture of granite affects the shear behavior of fractures remains e...The mineralogy and texture of granite have been found to have a pronounced effect on its mechanical behavior.However,the precise manner in which the texture of granite affects the shear behavior of fractures remains enigmatic.In this study,fine-grained granite(FG)and coarse-grained granite(CG)were used to create tensile fractures with surface roughness(i.e.joint roughness coefficient(JRC))within the range of 5.48-8.34 and 12.68-16.5,respectively.The pre-fractured specimens were then subjected to direct shear tests under normal stresses of 1-30 MPa.The results reveal that shear strengths are smaller and stick-slip behaviors are more intense for FG fractures than for CG fractures,which is attributed to the different conditions of the shear surface constrained by the grain size.The smaller grain size in FG contributes to the smoother fracture surface and lower shear strength.The negative friction rate parameter a-b for both CG and FG fractures and the larger shear stiffness for FG than for CG fractures can account for the more intense stick-slip behaviors in FG fractures.The relative crack density for the post-shear CG fractures is greater than that of the FG fractures under the same normal stress,both of which decrease with the distance away from the shear surface following the power law.Moreover,the damage of CG fracture extends to a larger extent beneath the surface compared with the FG fracture.Our findings demonstrate that the grain size of the host rock exerts a significant influence on the fracture roughness,and thus should be incorporated into the assessment of fault slip behavior to better understand the role of mineralogy and texture in seismic activities.展开更多
Background:The rate of distant metastasis in patients with pancreatic neuroendocrine tumors(PNETs)is20%-50%at the time of initial diagnosis.However,whether tumor size can predict distant metastasis for PNETs remains u...Background:The rate of distant metastasis in patients with pancreatic neuroendocrine tumors(PNETs)is20%-50%at the time of initial diagnosis.However,whether tumor size can predict distant metastasis for PNETs remains unknown up to date.Methods:We used Surveillance,Epidemiology,and End Results(SEER)population-based data to collect6089 patients with PNETs from 2010 to 2019.The optimal cut-off point of tumor size to predict distant metastasis was calculated by Youden’s index.Multivariate logistic regression analysis was used to figure out the association between tumor size and distant metastasis patterns.Results:The most common metastatic site was liver(27.2%),followed by bone(3.0%),lung(2.3%)and brain(0.4%).Based on an optimal cut-off value of tumor size(25.5 mm)for predicting distant metastasis determined by Youden’s index,patients were categorized into groups of tumor size<25.5 mm and≥25.5 mm.Multivariate logistic regression analyses showed that,compared with<25.5 mm,tumor size≥25.5 mm was an independent risk predictor of overall distant metastasis[odds ratio(OR)=4.491,95%confidence interval(CI):3.724-5.416,P<0.001]and liver metastasis(OR=4.686,95%CI:3.886-5.651,P<0.001).Conclusions:Tumor size≥25.5 mm was significantly associated with more overall distant and liver metastases.Timely identification of distant metastasis for tumor size≥25.5 mm may provide survival benefit for timely and precise treatment.展开更多
In a study comparing grain filling and yield in a large-and a small-grain-size wheat cultivar under two planting patterns and two irrigation regimes,plastic-covered ridge and furrow planting with sprinkler irrigation ...In a study comparing grain filling and yield in a large-and a small-grain-size wheat cultivar under two planting patterns and two irrigation regimes,plastic-covered ridge and furrow planting with sprinkler irrigation increased grain filling and yield in both cultivars.The largest contributors to grain yield were an extended active grain-filling period in Shuangda 1 and an increased mean grain-filling rate in XN538.展开更多
[Objectives]This study was conducted to screen suitable seed stems of Fritillaria thunbergii Miq.from different provenances and to provide a theoretical basis for the high-yielding and high-efficiency cultivation of F...[Objectives]This study was conducted to screen suitable seed stems of Fritillaria thunbergii Miq.from different provenances and to provide a theoretical basis for the high-yielding and high-efficiency cultivation of F.thunbergii Miq.introduced to different places.[Methods]F.thunbergii Miq.from four different provenances including Zhejiang,Nantong and Chongqing were introduced and cultivated in Wanzhou of Chongqing.The contents of available Zn,Fe,Mn,Cu,Mo,N,P,K,Ca and Mg in rhizosphere soil of F.thunbergii Miq.during five growing stages were determined after selecting different stem sizes for field cultivation.[Results]Small stems of Pan an and Ningbo provenances(SSG3,121-160/kg)and middle stems of Nantong and Fengjie provenances(SSG2,81-120/kg)showed higher soil availability.[Conclusions]In the process of introduction and cultivation of F.thunbergii Miq.,high yield and high efficiency can be achieved by selecting smaller seed stems of F.thunbergii Miq.展开更多
To clarify the effect of SnO2 particle size on the arc erosion behavior of AgSnO2 contact material, Ag?4%SnO2 (mass fraction) contact materials with different sizes of SnO2 particles were fabricated by powder metallur...To clarify the effect of SnO2 particle size on the arc erosion behavior of AgSnO2 contact material, Ag?4%SnO2 (mass fraction) contact materials with different sizes of SnO2 particles were fabricated by powder metallurgy. The microstructure of Ag?4%SnO2 contact materials was characterized, and the relative density, hardness and electrical conductivity were measured. The arc erosion of Ag?4%SnO2 contact materials was tested, the arc duration and mass loss before and after arc erosion were determined, the surface morphologies and compositions of Ag?4%SnO2 contact materials after arc erosion were characterized, and the arc erosion mechanism of AgSnO2 contact materials was discussed. The results show that fine SnO2 particle is beneficial for the improvement of the relative density and hardness, but decreases the electrical conductivity. With the decrease of SnO2 particle size, Ag?4%SnO2contact material presents shorter arc duration, less mass loss, larger erosion area and shallower arc erosion pits.展开更多
The formation and development of weather events has a great impact on the diffusion, accumulation and transport of air pollutants, and causes great changes in the particulate pollution level. It is very important to s...The formation and development of weather events has a great impact on the diffusion, accumulation and transport of air pollutants, and causes great changes in the particulate pollution level. It is very important to study their influence on particulate pollution. Lanzhou is one of the most particulate-polluted cities in China and even in the world. Particulate matter （PM） including TSP, PM〉10, PMzs-10, PM2.5 and PM1.0 concentrations were simultaneously measured during 2005-2007 in Lanzhou to evaluate the influence of three kinds of weather events - dost, precipitation and cold front - on the concentrations of PM with different sizes and detect the temporal evolution. The main results are as follows： （1） the PM pollution in Lanzhou during dust events was very heavy and the rate of increase in the concentration of PM2.5-10 was the highest of the five kinds of particles. During dust-storm events, the highest peaks of the concentrations of fine particles （PM2.5 and PM1.0） occurred 3 hr later than those of coarse particles （PM〉10 and PM/.5-10）. （2） The major effect of precipitation events on PM is wet scavenging. The scavenging rates of particles were closely associated with the kinds of precipitation events. The scavenging rates of TSP, PM〉10 and PMa.5-10 by convective precipitation were several times as high as those caused by frontal precipitation for the same precipitation amount, the reason being the different formation mechanism and precipitation characteristics of the two kinds of precipitation. Moreover, there exists a limiting value for the scavenging rates of particles by precipitation. （3） The major effect of cold-front events on particles is clearance. However, during cold-front passages, the PM concentrations could sometimes rise first and decrease afterwards, which is the critical difference in the influence of cold fronts on the concentrations of particulate pollutants vs. gaseous pollutants.展开更多
The significance of soil mineral properties and secondary environmental conditions such as pH, temperature, ionic strength and time in the partitioning of eight selected polychlorinated biphenyl(PCB) congeners between...The significance of soil mineral properties and secondary environmental conditions such as pH, temperature, ionic strength and time in the partitioning of eight selected polychlorinated biphenyl(PCB) congeners between aqueous solution and soil particles with different grain sizes was studied. The mineral properties of a model soil sample were determined, and Brunauer–Emmett–Teller(BET) adsorption–desorption isotherms were employed to observe the surface characteristics of the individual modeled soil particles.Batch adsorption experiments were conducted to determine the sorption of PCBs onto soil particles of different sizes. The results revealed that the sorption of PCB congeners onto the soil was dependent on the amount of soil organic matter, surface area, and pore size distribution of the various individual soil particles. Low pH favored the sorption of PCBs,with maximum sorption occurring between pH 6.5 and 7.5 with an equilibration period of 8 hr.Changes in the ionic strength were found to be less significant. Low temperature favored the sorption of PCBs onto the soil compared to high temperatures. Thermodynamic studies showed that the partition coefficient(K_d) decreased with increasing temperature, and negative and low values of ΔH° indicated an exothermic physisorption process. The data generated is critical and will help in further understanding remediation and cleanup strategies for polluted water.展开更多
A good method of synthesizing Ti_(3)C_(2)T_(x)(MXene)is critical for ensuring its success in practical applications,e.g.,electromagnetic interference shielding,electrochemical energy storage,catalysis,sensors,and biom...A good method of synthesizing Ti_(3)C_(2)T_(x)(MXene)is critical for ensuring its success in practical applications,e.g.,electromagnetic interference shielding,electrochemical energy storage,catalysis,sensors,and biomedicine.The main concerns focus on the moderation of the approach,yield,and product quality.Herein,a modified approach,organic solvent-assisted intercalation and collection,was developed to prepare Ti_(3)C_(2)T_(x) flakes.The new approach simultaneously solves all the concerns,featuring a low requirement for facility(centrifugation speed<4000 rpm in whole process),gram-level preparation with remarkable yield(46.3%),a good electrical conductivity(8672 S cm^(−1)),an outstanding capacitive performance(352 F g^(−1)),and easy control over the dimension of Ti_(3)C_(2)T_(x) flakes(0.47–4.60μm^(2)).This approach not only gives a superb example for the synthesis of other MXene materials in laboratory,but sheds new light for the future mass production of Ti_(3)C_(2)T_(x) MXene.展开更多
A homogenisation model for analysing the effect of micrometre pore sizes on the engineering moduli of elasticity of porous materials was proposed.In the proposed model,the engineering coefficients of localization of t...A homogenisation model for analysing the effect of micrometre pore sizes on the engineering moduli of elasticity of porous materials was proposed.In the proposed model,the engineering coefficients of localization of total strains(LTS coefficients)are considered instead of the classical strain localization tensors.For a pore,these coefficients represent the ratio of the sum of the strains in the volume of the pore to the sum of the strains in the volume of the porous body.To estimate the elastic moduli of a material with an arbitrary pore size,it is sufficient to have information about the elastic moduli and the LTS coefficient of a material with one basic pore size.Then,in Eshelby's model of equivalent inclusion,a transition to LTS coefficient for material with arbitrary pore size is achieved,and its elasticity moduli are determined.The results for Young's modulus of porous titanium,with different sizes of spherical pores,completely conform with the experimental data.We have obtained a model theoretic estimate of the upper bounds of Young's modulus of porous materials with infinitely small pore size.For the spherical pores,the proposed assessment coincides with the upper limits of the Hashin-Shtrikman bounds.展开更多
Garment online shopping has been accepted by more and more consumers in recent years. In online shopping, a buyer only chooses the garment size judged by his own experience without trying-on, so the selected garment m...Garment online shopping has been accepted by more and more consumers in recent years. In online shopping, a buyer only chooses the garment size judged by his own experience without trying-on, so the selected garment may not be the fittest one for the buyer due to the variety of body's figures. Thus, we propose a method of optimal selection of garment sizes for online shopping based on Analytic Hierarchy Process (AHP). The hierarchical structure model for optimal selection of garment sizes is structured and the fittest garment for a buyer is found by calculating the matching degrees between individual's measurements and the corresponding key-part values of ready-to-wear clothing sizes. In order to demonstrate its feasibility, we provide an example of selecting the fittest sizes of men's bottom. The result shows that the proposed method is useful in online clothing sales application.展开更多
Ru nanoparticles with different sizes confined in the cavities of mesoporous SBA-16 have been successfully synthesized by incipient wetness impregnation method with a Ru loading of 4 wt%. The catalysts were characteri...Ru nanoparticles with different sizes confined in the cavities of mesoporous SBA-16 have been successfully synthesized by incipient wetness impregnation method with a Ru loading of 4 wt%. The catalysts were characterized by XRD, N2 adsorption-desorption, H2-TPR, H2-TPD, O2-titration and TEM. The catalytic performance of Fischer-Tropsch synthesis over the catalyst was tested in a fixed-bed reactor. The addition of citric acid in the impregnation procedure shows a significant influence on the size of Ru nanoparticles. The selectivity to C5＋ increases, while the selectivities to methane and C2-C4 light hydrocarbons decrease with Ru average particles size from 2.0 nm to 9.3 nm, . The Ru catalyst confined in the SBA-16 with average nanoparticle size of 5.3 nm gives the best activity.展开更多
We investigate a novel Ga As-based laser power converters(LPCs) grown by metal-organic chemical vapor deposition(MOCVD),which uses a single monolithic structure with six junctions connected by tunnel junctions to obta...We investigate a novel Ga As-based laser power converters(LPCs) grown by metal-organic chemical vapor deposition(MOCVD),which uses a single monolithic structure with six junctions connected by tunnel junctions to obtain a high output voltage. The LPCs with diameters of active aperture of 2 mm and 4 mm were fabricated and tested. The test results show that under an 808 nm laser,two LPCs both show an open circuit voltage of above 6.5 V. A maximum power conversion efficiency of 50.2% is obtained by 2 mm sample with laser power of 0.256 W,and an output electric power of 1.9 W with laser power of 4.85 W is obtained by 4 mm sample. The performances of the LPCs are deteriorated under illumination of high flux,and the 4 mm sample shows a higher laser power tolerance.展开更多
Knowing the developmental states of stored grain insects, especially for the immature stages hidden in cereal kernel, such as Sitophilus zeamais, could be in favor of monitoring early and controlling effectively. Atla...Knowing the developmental states of stored grain insects, especially for the immature stages hidden in cereal kernel, such as Sitophilus zeamais, could be in favor of monitoring early and controlling effectively. Atlas and scale parameters on different developmental stages of S. zeamais in wheat kernel were captured and described by three-dimensional microscope of super depth of field observation. The four instars of larva, pre-pupa, pupa, new adult, old adult in kernel could be seen by dissecting the infested kernels. The length, height, and width of larva body increased with insect development and centralized the sizes corresponding to the four instars of larva. The length of larva body centralized near 554, 746, 1 462, and 2 147 μm. The height of larva body centralized about 388, 575, 847, and 1 651 μm. The width of larva body centralized near 340, 598, 798, and 1 568 μm. Head capsule width was in same size for each exuviating period, centralized near 203, 317, 535, and 603 μm, and got big sharply with the instar changed. Developmental duration of four larva instars was about 21 days reared in wheat, less than 28 days reared in maize as published. The atlas and description should be helpful for monitoring the S. zeamais development hidden in cereal kernels and designing control strategy.展开更多
Effects of shear rates on average cluster sizes (ACSs) and cluster size distributions (CSDs) in uni- and bi-systems of partly charged superfine nickel particles were investigated by Brownian dynamics, and clustering p...Effects of shear rates on average cluster sizes (ACSs) and cluster size distributions (CSDs) in uni- and bi-systems of partly charged superfine nickel particles were investigated by Brownian dynamics, and clustering properties in these systems were compared with those in non-polar systems. The results show that the ACSs in bi-polar systems are larger than those in the non-polar systems. In uni-polar systems the behavior of clustering property differs: at the lower ionic concentration (10%), repulsive force is not strong enough to break clusters, but may greatly weaken them. The clusters are eventually cracked into smaller ones only when concentration of uni-polar charged particles is large enough. In this work, the ionic concentration is 20%. The relationship between ACS and shear rates follows power law in a exponent range of 0.176-0.276. This range is in a good agreement with the range of experimental data, but it is biased towards the lower limit slightly.展开更多
The precise and accurate knowledge of genetic parameters is a prerequisite for making efficient selection strategies in breeding programs.A number of estimators of heritability about important economic traits in many ...The precise and accurate knowledge of genetic parameters is a prerequisite for making efficient selection strategies in breeding programs.A number of estimators of heritability about important economic traits in many marine mollusks are available in the literature,however very few research have evaluated about the accuracy of genetic parameters estimated with different family structures.Thus,in the present study,the effect of parent sample size for estimating the precision of genetic parameters of four growth traits in clam M.meretrix by factorial designs were analyzed through restricted maximum likelihood（REML） and Bayesian.The results showed that the average estimated heritabilities of growth traits obtained from REML were 0.23-0.32 for 9 and 16 full-sib families and 0.19-0.22 for 25 full-sib families.When using Bayesian inference,the average estimated heritabilities were0.11-0.12 for 9 and 16 full-sib families and 0.13-0.16 for 25 full-sib families.Compared with REML,Bayesian got lower heritabilities,but still remained at a medium level.When the number of parents increased from 6 to 10,the estimated heritabilities were more closed to 0.20 in REML and 0.12 in Bayesian inference.Genetic correlations among traits were positive and high and had no significant difference between different sizes of designs.The accuracies of estimated breeding values from the 9 and 16 families were less precise than those from 25 families.Our results provide a basic genetic evaluation for growth traits and should be useful for the design and operation of a practical selective breeding program in the clam M.meretrix.展开更多
Sizes of nuggets are often used to evaluate spot weld quality in production. This paper presents a neural estimator used to carry out non-destructive on-line analysis of spot weld quality in which trained ANN function...Sizes of nuggets are often used to evaluate spot weld quality in production. This paper presents a neural estimator used to carry out non-destructive on-line analysis of spot weld quality in which trained ANN functions to map dynamic resistance characteristics into sizes of spot weld nuggets and results confirm the validity of neural network for this type of application.展开更多
The concept of the flowing film jigging was first applied to the flowing film concentration area.The flowingfilm jigging function is an important element of the new process,in jection-flowing film centrifugation(IFFC)...The concept of the flowing film jigging was first applied to the flowing film concentration area.The flowingfilm jigging function is an important element of the new process,in jection-flowing film centrifugation(IFFC),for separating and recovering minerals of ultrafine sizes.展开更多
1Introduction Due to the easy loss and decomposition of traditional chemical pesticides,their repeated application in agriculture results in serious environmental risks to the surrounding environment and organisms.Con...1Introduction Due to the easy loss and decomposition of traditional chemical pesticides,their repeated application in agriculture results in serious environmental risks to the surrounding environment and organisms.Controlledrelease nanopesticides are attracting attention as a promising technology in agriculture due to their unique structure and effects(e.g.,nano-size scale,interfacial effects,and effective insecticidal time)(An et al.,2022).Their application could improve insecticidal efficacies,decrease usage amounts,and reduce the potential environmental impacts of chemical pesticides.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos.12202294 and 12022208)the Project funded by China Postdoctoral Science Foundation (Grant No.2022M712243)the Fundamental Research Funds for the Central Universities (Grant No.2023SCU12098).
文摘It is well known that coarse-grained super-elastic NiTi shape memory alloys(SMAs)exhibit localized rather than homogeneous martensite transformation(MT),which,however,can be strongly influenced by either internal size(grain size,GS)or the external size(geometric size).The coupled effect of GS and geometric size on the functional properties has not been clearly understood yet.In this work,the super-elasticity,one-way,and stress-assisted two-way shape memory effects of the polycrystalline NiTi SMAs with different aspect ratios(length/width for the gauge section)and different GSs are investigated based on the phase field method.The coupled effect of the aspect ratio and GS on the functional properties is adequately revealed.The simulated results indicate that when the aspect ratio is lower than about 4:1,the stress biaxiality and stress heterogeneity in the gauge section of the sample become more and more obvious with decreasing the aspect ratio,which can significantly influence the microstructure evolution in the process involving external stress.Therefore,the corresponding functional property is strongly dependent on the aspect ratio.With decreasing the GS and the aspect ratio(to be lower than 4:1),both the aspect ratio and GS can affect the MT or martensite reorientation in each grain and the interaction among grains.Thus,due to the strong internal constraint(i.e.,the constraint of grain boundary)and the external constraint(i.e.,the constraint of geometric boundary),the capabilities of the functional properties of NiTi SMAs are gradually weakened and highly dependent on these two factors.
基金supported financially by the National Natural Science Foundation of China(Grant No.12275047).
文摘In ball milling,the process parameters are decisive in influencing the quality and performance of the final ball-milled product,and crucial but often neglected is the ratio of the grinding balls in terms of their size.Here,for a given number of large grinding balls,the ratio of large to small ones is set to 1:2,1:3,1:4,and 1:5 by altering the number of small ones,and how this affects the morphology,structure,and electrochemical properties of ball-milled graphene nanosheets is investigated.The results show that changing the ball ratio causes distinct changes in the morphology,structure,and properties of the graphene nanosheets.Increasing the number of small(6 mm)grinding balls decreases the nanosheet grain size monotonically;meanwhile,the crystal plane spacing,defect density,and specific surface area increase and then decrease,but the graphitization degree decreases and then increases.Ball-milled samples are then used as anodes for lithium-ion batteries,and both the specific capacity and rate capability exhibit the same trend of increase and then decrease.The ball ratio of 1:3 gives the best electrochemical performance,i.e.,a reversible specific capacity of 262.09 mA·h/g at a current density of 100 mA/g,and even after 2000 cycles at 2000 mA/g,the reversible specific capacity is 87.4%of the optimal value.
基金the National Natural Science Foundation of China(Grant No.52309130)the Natural Science Foundation of Shandong Province(Grant No.ZR2022QD004).
文摘The mineralogy and texture of granite have been found to have a pronounced effect on its mechanical behavior.However,the precise manner in which the texture of granite affects the shear behavior of fractures remains enigmatic.In this study,fine-grained granite(FG)and coarse-grained granite(CG)were used to create tensile fractures with surface roughness(i.e.joint roughness coefficient(JRC))within the range of 5.48-8.34 and 12.68-16.5,respectively.The pre-fractured specimens were then subjected to direct shear tests under normal stresses of 1-30 MPa.The results reveal that shear strengths are smaller and stick-slip behaviors are more intense for FG fractures than for CG fractures,which is attributed to the different conditions of the shear surface constrained by the grain size.The smaller grain size in FG contributes to the smoother fracture surface and lower shear strength.The negative friction rate parameter a-b for both CG and FG fractures and the larger shear stiffness for FG than for CG fractures can account for the more intense stick-slip behaviors in FG fractures.The relative crack density for the post-shear CG fractures is greater than that of the FG fractures under the same normal stress,both of which decrease with the distance away from the shear surface following the power law.Moreover,the damage of CG fracture extends to a larger extent beneath the surface compared with the FG fracture.Our findings demonstrate that the grain size of the host rock exerts a significant influence on the fracture roughness,and thus should be incorporated into the assessment of fault slip behavior to better understand the role of mineralogy and texture in seismic activities.
基金supported by a grant from the National Natural Science Foundation of China(82173353)。
文摘Background:The rate of distant metastasis in patients with pancreatic neuroendocrine tumors(PNETs)is20%-50%at the time of initial diagnosis.However,whether tumor size can predict distant metastasis for PNETs remains unknown up to date.Methods:We used Surveillance,Epidemiology,and End Results(SEER)population-based data to collect6089 patients with PNETs from 2010 to 2019.The optimal cut-off point of tumor size to predict distant metastasis was calculated by Youden’s index.Multivariate logistic regression analysis was used to figure out the association between tumor size and distant metastasis patterns.Results:The most common metastatic site was liver(27.2%),followed by bone(3.0%),lung(2.3%)and brain(0.4%).Based on an optimal cut-off value of tumor size(25.5 mm)for predicting distant metastasis determined by Youden’s index,patients were categorized into groups of tumor size<25.5 mm and≥25.5 mm.Multivariate logistic regression analyses showed that,compared with<25.5 mm,tumor size≥25.5 mm was an independent risk predictor of overall distant metastasis[odds ratio(OR)=4.491,95%confidence interval(CI):3.724-5.416,P<0.001]and liver metastasis(OR=4.686,95%CI:3.886-5.651,P<0.001).Conclusions:Tumor size≥25.5 mm was significantly associated with more overall distant and liver metastases.Timely identification of distant metastasis for tumor size≥25.5 mm may provide survival benefit for timely and precise treatment.
基金supported by the National Key Research and Development Program of China(2017YFD0300202-2)the National Natural Science Foundation of China(31871567)the Young Scholar of Tang(2017)。
文摘In a study comparing grain filling and yield in a large-and a small-grain-size wheat cultivar under two planting patterns and two irrigation regimes,plastic-covered ridge and furrow planting with sprinkler irrigation increased grain filling and yield in both cultivars.The largest contributors to grain yield were an extended active grain-filling period in Shuangda 1 and an increased mean grain-filling rate in XN538.
基金Supported by Technological Innovation and Application Demonstration Project of Chongqing City(cstc2018jscx-msybX0367).
文摘[Objectives]This study was conducted to screen suitable seed stems of Fritillaria thunbergii Miq.from different provenances and to provide a theoretical basis for the high-yielding and high-efficiency cultivation of F.thunbergii Miq.introduced to different places.[Methods]F.thunbergii Miq.from four different provenances including Zhejiang,Nantong and Chongqing were introduced and cultivated in Wanzhou of Chongqing.The contents of available Zn,Fe,Mn,Cu,Mo,N,P,K,Ca and Mg in rhizosphere soil of F.thunbergii Miq.during five growing stages were determined after selecting different stem sizes for field cultivation.[Results]Small stems of Pan an and Ningbo provenances(SSG3,121-160/kg)and middle stems of Nantong and Fengjie provenances(SSG2,81-120/kg)showed higher soil availability.[Conclusions]In the process of introduction and cultivation of F.thunbergii Miq.,high yield and high efficiency can be achieved by selecting smaller seed stems of F.thunbergii Miq.
基金Project(51274163)supported by the National Natural Science Foundation of ChinaProject(13JS076)supported by the Key Laboratory Research Program of Shaanxi Province,China+1 种基金Project(2012KCT-25)supported by the Pivot Innovation Team of Shaanxi Electrical Materials and Infiltration Technique,ChinaProject(2011HBSZS009)supported by the Special Foundation of Key Disciplines,China
文摘To clarify the effect of SnO2 particle size on the arc erosion behavior of AgSnO2 contact material, Ag?4%SnO2 (mass fraction) contact materials with different sizes of SnO2 particles were fabricated by powder metallurgy. The microstructure of Ag?4%SnO2 contact materials was characterized, and the relative density, hardness and electrical conductivity were measured. The arc erosion of Ag?4%SnO2 contact materials was tested, the arc duration and mass loss before and after arc erosion were determined, the surface morphologies and compositions of Ag?4%SnO2 contact materials after arc erosion were characterized, and the arc erosion mechanism of AgSnO2 contact materials was discussed. The results show that fine SnO2 particle is beneficial for the improvement of the relative density and hardness, but decreases the electrical conductivity. With the decrease of SnO2 particle size, Ag?4%SnO2contact material presents shorter arc duration, less mass loss, larger erosion area and shallower arc erosion pits.
基金supported by the National Special Project for Commonweal Industry in China (No. GY-HY201006023,GYHY201106034)the National Support Projects for Science and Technology in China (No.2009BAC53B02)+2 种基金the Project of National Natural Science Foundation of China (No. 41075103)the Application and Foundation Research Program of Sichuan Province (No.2009JY0116)the Project of the Scientific Research Foundation of CUIT (No. KYTZ201008)
文摘The formation and development of weather events has a great impact on the diffusion, accumulation and transport of air pollutants, and causes great changes in the particulate pollution level. It is very important to study their influence on particulate pollution. Lanzhou is one of the most particulate-polluted cities in China and even in the world. Particulate matter （PM） including TSP, PM〉10, PMzs-10, PM2.5 and PM1.0 concentrations were simultaneously measured during 2005-2007 in Lanzhou to evaluate the influence of three kinds of weather events - dost, precipitation and cold front - on the concentrations of PM with different sizes and detect the temporal evolution. The main results are as follows： （1） the PM pollution in Lanzhou during dust events was very heavy and the rate of increase in the concentration of PM2.5-10 was the highest of the five kinds of particles. During dust-storm events, the highest peaks of the concentrations of fine particles （PM2.5 and PM1.0） occurred 3 hr later than those of coarse particles （PM〉10 and PM/.5-10）. （2） The major effect of precipitation events on PM is wet scavenging. The scavenging rates of particles were closely associated with the kinds of precipitation events. The scavenging rates of TSP, PM〉10 and PMa.5-10 by convective precipitation were several times as high as those caused by frontal precipitation for the same precipitation amount, the reason being the different formation mechanism and precipitation characteristics of the two kinds of precipitation. Moreover, there exists a limiting value for the scavenging rates of particles by precipitation. （3） The major effect of cold-front events on particles is clearance. However, during cold-front passages, the PM concentrations could sometimes rise first and decrease afterwards, which is the critical difference in the influence of cold fronts on the concentrations of particulate pollutants vs. gaseous pollutants.
文摘The significance of soil mineral properties and secondary environmental conditions such as pH, temperature, ionic strength and time in the partitioning of eight selected polychlorinated biphenyl(PCB) congeners between aqueous solution and soil particles with different grain sizes was studied. The mineral properties of a model soil sample were determined, and Brunauer–Emmett–Teller(BET) adsorption–desorption isotherms were employed to observe the surface characteristics of the individual modeled soil particles.Batch adsorption experiments were conducted to determine the sorption of PCBs onto soil particles of different sizes. The results revealed that the sorption of PCB congeners onto the soil was dependent on the amount of soil organic matter, surface area, and pore size distribution of the various individual soil particles. Low pH favored the sorption of PCBs,with maximum sorption occurring between pH 6.5 and 7.5 with an equilibration period of 8 hr.Changes in the ionic strength were found to be less significant. Low temperature favored the sorption of PCBs onto the soil compared to high temperatures. Thermodynamic studies showed that the partition coefficient(K_d) decreased with increasing temperature, and negative and low values of ΔH° indicated an exothermic physisorption process. The data generated is critical and will help in further understanding remediation and cleanup strategies for polluted water.
基金This work was financially supported by National Natural Science Foundation of China(No.51903197)Wuhu and Xidian University special fund for industry-universityresearch cooperation(No.XWYCXY-012020012)+3 种基金Open Fund of Zhijiang Lab(2021MC0AB02)China Postdoctoral Science Foundation(2019TQ02422019M660061XB)the Fundamental Research Funds for the Central Universities(JC2110,JB211305).
文摘A good method of synthesizing Ti_(3)C_(2)T_(x)(MXene)is critical for ensuring its success in practical applications,e.g.,electromagnetic interference shielding,electrochemical energy storage,catalysis,sensors,and biomedicine.The main concerns focus on the moderation of the approach,yield,and product quality.Herein,a modified approach,organic solvent-assisted intercalation and collection,was developed to prepare Ti_(3)C_(2)T_(x) flakes.The new approach simultaneously solves all the concerns,featuring a low requirement for facility(centrifugation speed<4000 rpm in whole process),gram-level preparation with remarkable yield(46.3%),a good electrical conductivity(8672 S cm^(−1)),an outstanding capacitive performance(352 F g^(−1)),and easy control over the dimension of Ti_(3)C_(2)T_(x) flakes(0.47–4.60μm^(2)).This approach not only gives a superb example for the synthesis of other MXene materials in laboratory,but sheds new light for the future mass production of Ti_(3)C_(2)T_(x) MXene.
文摘A homogenisation model for analysing the effect of micrometre pore sizes on the engineering moduli of elasticity of porous materials was proposed.In the proposed model,the engineering coefficients of localization of total strains(LTS coefficients)are considered instead of the classical strain localization tensors.For a pore,these coefficients represent the ratio of the sum of the strains in the volume of the pore to the sum of the strains in the volume of the porous body.To estimate the elastic moduli of a material with an arbitrary pore size,it is sufficient to have information about the elastic moduli and the LTS coefficient of a material with one basic pore size.Then,in Eshelby's model of equivalent inclusion,a transition to LTS coefficient for material with arbitrary pore size is achieved,and its elasticity moduli are determined.The results for Young's modulus of porous titanium,with different sizes of spherical pores,completely conform with the experimental data.We have obtained a model theoretic estimate of the upper bounds of Young's modulus of porous materials with infinitely small pore size.For the spherical pores,the proposed assessment coincides with the upper limits of the Hashin-Shtrikman bounds.
基金The Programfor New Century Excellent Talents in University from Ministry of Education of China(No.NCET-04-415)the Cultivation Fund of the Key Scientific and Technical Innovation Project from Ministry of Education of China(No.706024)International Science Cooperation Foundation of Shanghai,China(No.061307041)
文摘Garment online shopping has been accepted by more and more consumers in recent years. In online shopping, a buyer only chooses the garment size judged by his own experience without trying-on, so the selected garment may not be the fittest one for the buyer due to the variety of body's figures. Thus, we propose a method of optimal selection of garment sizes for online shopping based on Analytic Hierarchy Process (AHP). The hierarchical structure model for optimal selection of garment sizes is structured and the fittest garment for a buyer is found by calculating the matching degrees between individual's measurements and the corresponding key-part values of ready-to-wear clothing sizes. In order to demonstrate its feasibility, we provide an example of selecting the fittest sizes of men's bottom. The result shows that the proposed method is useful in online clothing sales application.
基金supported by the National Natural Science foundation of China(21073238)the National Basic Research Program of China(2011CB211704)+1 种基金the Natural Science Foundation of Hubei Province of China(Grant No.2009CDA049)the Special Fund for basic Scientific Research of Central Colleges,South-Central University for Nationalities(Grant No.ZZY10005)
文摘Ru nanoparticles with different sizes confined in the cavities of mesoporous SBA-16 have been successfully synthesized by incipient wetness impregnation method with a Ru loading of 4 wt%. The catalysts were characterized by XRD, N2 adsorption-desorption, H2-TPR, H2-TPD, O2-titration and TEM. The catalytic performance of Fischer-Tropsch synthesis over the catalyst was tested in a fixed-bed reactor. The addition of citric acid in the impregnation procedure shows a significant influence on the size of Ru nanoparticles. The selectivity to C5＋ increases, while the selectivities to methane and C2-C4 light hydrocarbons decrease with Ru average particles size from 2.0 nm to 9.3 nm, . The Ru catalyst confined in the SBA-16 with average nanoparticle size of 5.3 nm gives the best activity.
基金supported by the National Natural Science Foundation of China(Nos.61376065 and 61604171)Zhongtian Technology Group Co.Ltd
文摘We investigate a novel Ga As-based laser power converters(LPCs) grown by metal-organic chemical vapor deposition(MOCVD),which uses a single monolithic structure with six junctions connected by tunnel junctions to obtain a high output voltage. The LPCs with diameters of active aperture of 2 mm and 4 mm were fabricated and tested. The test results show that under an 808 nm laser,two LPCs both show an open circuit voltage of above 6.5 V. A maximum power conversion efficiency of 50.2% is obtained by 2 mm sample with laser power of 0.256 W,and an output electric power of 1.9 W with laser power of 4.85 W is obtained by 4 mm sample. The performances of the LPCs are deteriorated under illumination of high flux,and the 4 mm sample shows a higher laser power tolerance.
基金Supported by National Keypoint Research and Invention Program of the Thirteenth(2017YFC1600804)
文摘Knowing the developmental states of stored grain insects, especially for the immature stages hidden in cereal kernel, such as Sitophilus zeamais, could be in favor of monitoring early and controlling effectively. Atlas and scale parameters on different developmental stages of S. zeamais in wheat kernel were captured and described by three-dimensional microscope of super depth of field observation. The four instars of larva, pre-pupa, pupa, new adult, old adult in kernel could be seen by dissecting the infested kernels. The length, height, and width of larva body increased with insect development and centralized the sizes corresponding to the four instars of larva. The length of larva body centralized near 554, 746, 1 462, and 2 147 μm. The height of larva body centralized about 388, 575, 847, and 1 651 μm. The width of larva body centralized near 340, 598, 798, and 1 568 μm. Head capsule width was in same size for each exuviating period, centralized near 203, 317, 535, and 603 μm, and got big sharply with the instar changed. Developmental duration of four larva instars was about 21 days reared in wheat, less than 28 days reared in maize as published. The atlas and description should be helpful for monitoring the S. zeamais development hidden in cereal kernels and designing control strategy.
基金Projects(50474037, 50874087) supported by the National Natural Science Foundation of ChinaProject (BK2006078) supported by the Natural Scientific Funds of Jiangsu Province,China
文摘Effects of shear rates on average cluster sizes (ACSs) and cluster size distributions (CSDs) in uni- and bi-systems of partly charged superfine nickel particles were investigated by Brownian dynamics, and clustering properties in these systems were compared with those in non-polar systems. The results show that the ACSs in bi-polar systems are larger than those in the non-polar systems. In uni-polar systems the behavior of clustering property differs: at the lower ionic concentration (10%), repulsive force is not strong enough to break clusters, but may greatly weaken them. The clusters are eventually cracked into smaller ones only when concentration of uni-polar charged particles is large enough. In this work, the ionic concentration is 20%. The relationship between ACS and shear rates follows power law in a exponent range of 0.176-0.276. This range is in a good agreement with the range of experimental data, but it is biased towards the lower limit slightly.
基金The National High Technology Research and Development Program(863 program)of China under contract No.2012AA10A410the Zhejiang Science and Technology Project of Agricultural Breeding under contract No.2012C12907-4the Scientific and Technological Innovation Project financially supported by Qingdao National Laboratory for Marine Science and Technology under contract No.2015ASKJ02
文摘The precise and accurate knowledge of genetic parameters is a prerequisite for making efficient selection strategies in breeding programs.A number of estimators of heritability about important economic traits in many marine mollusks are available in the literature,however very few research have evaluated about the accuracy of genetic parameters estimated with different family structures.Thus,in the present study,the effect of parent sample size for estimating the precision of genetic parameters of four growth traits in clam M.meretrix by factorial designs were analyzed through restricted maximum likelihood（REML） and Bayesian.The results showed that the average estimated heritabilities of growth traits obtained from REML were 0.23-0.32 for 9 and 16 full-sib families and 0.19-0.22 for 25 full-sib families.When using Bayesian inference,the average estimated heritabilities were0.11-0.12 for 9 and 16 full-sib families and 0.13-0.16 for 25 full-sib families.Compared with REML,Bayesian got lower heritabilities,but still remained at a medium level.When the number of parents increased from 6 to 10,the estimated heritabilities were more closed to 0.20 in REML and 0.12 in Bayesian inference.Genetic correlations among traits were positive and high and had no significant difference between different sizes of designs.The accuracies of estimated breeding values from the 9 and 16 families were less precise than those from 25 families.Our results provide a basic genetic evaluation for growth traits and should be useful for the design and operation of a practical selective breeding program in the clam M.meretrix.
文摘Sizes of nuggets are often used to evaluate spot weld quality in production. This paper presents a neural estimator used to carry out non-destructive on-line analysis of spot weld quality in which trained ANN functions to map dynamic resistance characteristics into sizes of spot weld nuggets and results confirm the validity of neural network for this type of application.
文摘The concept of the flowing film jigging was first applied to the flowing film concentration area.The flowingfilm jigging function is an important element of the new process,in jection-flowing film centrifugation(IFFC),for separating and recovering minerals of ultrafine sizes.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LD21B070001)。
文摘1Introduction Due to the easy loss and decomposition of traditional chemical pesticides,their repeated application in agriculture results in serious environmental risks to the surrounding environment and organisms.Controlledrelease nanopesticides are attracting attention as a promising technology in agriculture due to their unique structure and effects(e.g.,nano-size scale,interfacial effects,and effective insecticidal time)(An et al.,2022).Their application could improve insecticidal efficacies,decrease usage amounts,and reduce the potential environmental impacts of chemical pesticides.
