To determine the effects of preharvest arginine spraying on the nutritional level of broccoli and the mechanism of action of arginine in improving the storage quality of broccoli,arginine spraying(5 mmol/L)was conduct...To determine the effects of preharvest arginine spraying on the nutritional level of broccoli and the mechanism of action of arginine in improving the storage quality of broccoli,arginine spraying(5 mmol/L)was conducted at 0,1,3,and 5 days before harvest.The appearance,respiration rate,mass-loss rate,electrolyte leakage,glucosinolate,ascorbic acid,total phenol,total flavonoid,total sugar and sucrose contents,and sucrose phosphate synthase(SPS),invertase(INV),sucrose synthase synthesis(SSS)and cleavage(SSC)activities of broccoli samples were observed after 0,2,4,6,8,and 10 days of storage.The results showed that spraying arginine at 5 days preharvest(5-ARG)helped to inhibit broccoli respiration during storage,delay electrolyte leakage,and maintain broccoli color.Furthermore,during the growth stage,total sugar accumulation was higher in the 5-ARG group.In addition,during the storage period,sucrose synthesis was accelerated,while sucrose cleavage was inhibited,resulting in more sucrose retention in postharvest broccoli.In conclusion,5-ARG resulted in the accumulation of more nutrients during the growth process and effectively delayed the quality decline during storage,thereby prolonging the shelf life of broccoli.Therefore,this study provides a theoretical basis for improving postharvest storage characteristics of broccoli through preharvest treatments.展开更多
Strip-till(ST),including straw mulching in the inter-row and localized fertilization in the intra-row,is a conservation tillage system for improving soil quality and crop growth.However,the yield advantage of maize un...Strip-till(ST),including straw mulching in the inter-row and localized fertilization in the intra-row,is a conservation tillage system for improving soil quality and crop growth.However,the yield advantage of maize under ST compared to conventional tillage(CT)remains unstable,and the strategies to increase maize yield under ST are unclear.This study aims to understand the physiological mechanism underlining maize yield formation under ST by comparing two maize cultivars,DKM753 and DK517,with contrasting yield performance in ST versus CT systems.Compared to CT,ST resulted in a 4.5%yield increase for DKM753 but a 5.6%decrease for DK517.These yield differences were primarily attributed to variations in grain number per ear(GN).During the rapid growth stage(V14-R3),i.e.,two weeks before and after silking,DKM753 showed a 6.7%increase in maximum growth rate(V_(max))and a 6.3%increase in average growth rate(V)under ST,whereas DK517 exhibited decline of 8.5%in V_(max) and 12.3%in V.Significant positive correlations are observed between V_(max) and V with GN under ST(R^(2)=0.79 and R^(2)=0.90,respectively).Enhanced dry matter accumulation in DKM753 under ST was attributed to increased leaf expansion rates,contributing to a larger photosynthate source.The straw mulching and localized nitrogen fertilization increased root-zone nitrogen availability at silking in ST compared to CT.DKM753 had a greater root system which made better use of the soil N and lead to an increased leaf nitrogen accumulation by 14.9%under ST.It is concluded that maize yield under the strip-till system is determined by grain number per ear,which can be increased by increasing nitrogen accumulation,plant growth,and ear development around silking stage.A sound root system can efficiently utilize soil nitrogen resources under the strip-till system,increasing plant nitrogen accumulation and thereby promoting plant growth.展开更多
Black soil is essential for maintaining regional food security and promoting global agricultural production.Understanding the weathering process of parent material and the accumulation of organic carbon is crucial to ...Black soil is essential for maintaining regional food security and promoting global agricultural production.Understanding the weathering process of parent material and the accumulation of organic carbon is crucial to comprehending the developmental history and future trends of black soil,especially against the background of large-scale global cultivation and climate change.Although the importance of black soil formation and evolution cannot be ignored,the relevant research is still very scarce.In this study,a typical eight-meter-deep soil core was collected from the Keshan area of the Songnen Plain,Northeast China,where surface black soil developed on paleo-sediments.Using^(14)C dating,the formation age of the black soil was determined.Based on the characteristics of the geochemical composition,grain size and the magnetic susceptibility of the sediments,it was demonstrated that the black soil and its parent material originated from reworked loess.Furthermore,the mass transfer coefficient(τ)of some elements was determined,in order to explore the soil weathering process.By calculating the transported amount of alkaline and alkaline-earth elements,the weathering rate of parent material to black soil was found to be weak,at 0.16 kEq·ha^(-1)·year^(-1).Combining the results of dating and carbon density in the different layers of black soil,the accumulation rate of organic carbon was determined as follows:rapidly increasing in the initial period of 13.2-2.2 ka,reaching its maximum average value of 34.0 g·cm^(-2)·a^(-1)at 2.2-0.8 ka,then showing a decreasing trend with an average value of-77.5 g·cm^(-2)·a^(-1).Compared with regional climate change,Keshan black soil has developed under a colder and wetter climate during the Holocene.Predictably,ongoing global warming may lead to the degradation of black soils in the Songnen Plain,as well as in other regions.Our results will enrich geological knowledge of black soil formation and future evolutionary trends.展开更多
Based on petroleum exploration and new progress of oil and gas geology study in the Qiongdongnan Basin,combined with seismic,logging,drilling,core,sidewall coring,geochemistry data,a systematic study is conducted on t...Based on petroleum exploration and new progress of oil and gas geology study in the Qiongdongnan Basin,combined with seismic,logging,drilling,core,sidewall coring,geochemistry data,a systematic study is conducted on the source,reservoir-cap conditions,trap types,migration and accumulation characteristics,enrichment mechanisms,and reservoir formation models of ultra-deep water and ultra-shallow natural gas,taking the Lingshui 36-1 gas field as an example.(1)The genetic types of the ultra-deep water and ultra-shallow natural gas in the Qiongdongnan Basin include thermogenic gas and biogenic gas,and dominated by thermogenic gas.(2)The reservoirs are mainly composed of the Quaternary deep-water submarine fan sandstone.(3)The types of cap rocks include deep-sea mudstone,mass transport deposits mudstone,and hydrate-bearing formations.(4)The types of traps are mainly lithological,and also include structural-lithological traps.(5)The migration channels include vertical transport channels such as faults,gas chimneys,fracture zones,and lateral transport layers such as large sand bodies and unconformity surfaces,forming a single or composite transport framework.A new natural gas accumulation model is proposed for ultra-deep water and ultra-shallow layers,that is,dual source hydrocarbon supply,gas chimney and submarine fan composite migration,deep-sea mudstone-mass transport deposits mudstone-hydrate-bearing strata ternary sealing,late dynamic accumulation,and large-scale enrichment at ridges.The new understanding obtained from the research has reference and enlightening significance for the next step of deepwater and ultra-shallow layers,as well as oil and gas exploration in related fields or regions.展开更多
Coal measures are significant hydrocarbon source rocks and reservoirs in petroliferous basins.Many large gas fields and coalbed methane fields globally are originated from coal-measure source rocks or accumulated in c...Coal measures are significant hydrocarbon source rocks and reservoirs in petroliferous basins.Many large gas fields and coalbed methane fields globally are originated from coal-measure source rocks or accumulated in coal rocks.Inspired by the discovery of shale oil and gas,and guided by“the overall exploration concept of considering coal rock as reservoir”,breakthroughs in the exploration and development of coal-rock gas have been achieved in deep coal seams with favorable preservation conditions,thereby opening up a new development frontier for the unconventional gas in coal-rock reservoirs.Based on the data from exploration and development practices,a systematic study on the accumulation mechanism of coal-rock gas has been conducted.The mechanisms of“three fields”controlling coal-rock gas accumulation are revealed.It is confirmed that the coal-rock gas is different from CBM in accumulation process.The whole petroleum systems in the Carboniferous–Permian transitional facies coal measures of the eastern margin of the Ordos Basin and in the Jurassic continental facies coal measures of the Junggar Basin are characterized,and the key research directions for further developing the whole petroleum system theory of coal measures are proposed.Coal rocks,compared to shale,possess intense hydrocarbon generation potential,strong adsorption capacity,dual-medium reservoir properties,and partial or weak oil and gas self-sealing capacity.Additionally,unlike other unconventional gas such as shale gas and tight gas,coal-rock gas exhibits more complex accumulation characteristics,and its accumulation requires a certain coal-rock play form lithological and structural traps.Coal-rock gas also has the characteristics of conventional fractured gas reservoirs.Compared with the basic theory and model of the whole petroleum system established based on detrital rock formations,coal measures have distinct characteristics and differences in coal-rock reservoirs and source-reservoir coupling.The whole petroleum system of coal measures is composed of various types of coal-measure hydrocarbon plays with coal(and dark shale)in coal measures as source rock and reservoir,and with adjacent tight layers as reservoirs or cap or transport layers.Under the action of source-reservoir coupling,coal-rock gas is accumulated in coal-rock reservoirs with good preservation conditions,tight oil/gas is accumulated in tight layers,conventional oil/gas is accumulated in traps far away from sources,and coalbed methane is accumulated in coal-rock reservoirs damaged by later geological processes.The proposed whole petroleum system of coal measures represents a novel type of whole petroleum system.展开更多
According to phenological observation data of fourteen stations in Hunan,Hubei and Jiangxi provinces from 1994 to 2006,indices of suitable temperature at the booting stage and accumulated temperature(≥10 ℃)during th...According to phenological observation data of fourteen stations in Hunan,Hubei and Jiangxi provinces from 1994 to 2006,indices of suitable temperature at the booting stage and accumulated temperature(≥10 ℃)during the whole growth period in early or late rice in the south of China were analyzed by statistics and biological relationship between factors.Indices of the optimum daily mean temperature and the minimum temperature at the booting stage were as follows:Early convention rice variety was 25.7 ℃ and 22.3 ℃ respectively,hybrid variety was 26.5 ℃ and 23.3℃ respectively;while late convention rice variety was 25.6 ℃ and 22.3 ℃ respectively,hybrid variety was 25.8 ℃ and 22.6 ℃ respectively.Indexes of accumulated temperature during the whole growth period were as follows:The early-maturing variety,the middle-maturing variety and the late-maturing variety of early rice was 2 512.1 ℃,2 528.4 ℃ and 2 651.3 ℃ respectively,while the early-maturing variety,the middle-maturing variety and the late-maturing variety of late rice was 3 126.2 ℃,3 031.5 ℃ and 3 335.2 ℃ respectively.The above indexes all met the requirements of identification,which could provide reference for formulating the meteorological standard of rice in the south of China.展开更多
[Objective]The research aimed at constructing an accumulated temperature effect model for fertility alteration of two-line hybrid rice P88S.[Method]Analyze the experiment datas of fertility alteration of P88S in Haina...[Objective]The research aimed at constructing an accumulated temperature effect model for fertility alteration of two-line hybrid rice P88S.[Method]Analyze the experiment datas of fertility alteration of P88S in Hainan from 2005 to 2006.[Result]The fertilities of P88S with temperatures ranging from 26 to 28 ℃ were determined by the absolute values and the accumulation effects of the temperature.An accumulation effect model of temperatures based on the bistable state was obtained.[Conclusion]The temperature asymmetry of fertility alteration for two-line sterility line in spring and autumn can be elucidated effectively using the accumulated temperature effect model,namely,alternating from fertile to sterile requires higher temperatures,and alternating from sterile to fertile requires lower temperatures.展开更多
Winter chill is essential for the growth and development of deciduous species. To understand the relationship between accumulated chilling hours during endodormancy and blooming and fruit shape development, we control...Winter chill is essential for the growth and development of deciduous species. To understand the relationship between accumulated chilling hours during endodormancy and blooming and fruit shape development, we controlled chilling hours and investigated their effects on blooming date and fruit shape of peaches. The results showed that the number of days to full bloom date and the heat requirement for blooming were negatively correlated with accumulated chilling hours. Accumulated chilling hours were significantly negatively correlated with fruit shape index and fruit tip lengths, suggesting that the number of chilling hours affect the fruit shape development. Fewer accumulated chilling hours may be the major reason for longer fruit shape and protruding fruit tips. In conclusion, our results indicate specifically that decreased winter chilling hours can delay the bloom date and may lead to aberrant fruit shape development in peaches. Our study provides preliminary insights into the response of temperate fruit species to global climate change.展开更多
Profile characteristics of accumulated P in 10 representativesoils of vegetable fields in suburban districts of Beijing wereinvestigated. Bioavailability of the accumulated P and its potentialeffect n the environment ...Profile characteristics of accumulated P in 10 representativesoils of vegetable fields in suburban districts of Beijing wereinvestigated. Bioavailability of the accumulated P and its potentialeffect n the environment were studied in a greenhouse pot experimentand a soil column experiment. The results showed that theconcentration of Olsen-P in the 0～20 cm soil samples of thevegetable fields ranged from 2.1 to 358.0 mg kg^-1, which was 2 to 10times higher than that of the crop field sin the suburbs of Beijing.Most of the excessive phosphorus was accumulated in the topsoils.展开更多
Rare earth elements(REE)are applied as micro-fertilizer in large scale in China and there is growing concern about the environmental effects of REE accumulation in soils. Accumulation of REE was simulated in lab by ad...Rare earth elements(REE)are applied as micro-fertilizer in large scale in China and there is growing concern about the environmental effects of REE accumulation in soils. Accumulation of REE was simulated in lab by adding REE to three soils and the survival of Pseudomonas fluorescence X16 strain marked with luxAB gene in soils was detected. Curvilinear regression method was applied to analyze the survival pattern. The stimulation values, EC_(50) and NOEC values for X16 strain were calculated to compare the toxic intensity of REE in different soils. The stimulation(peak)values in red soil, yellow fluovo-aquic soil and yellow cinnamon soil, are 11.55～18.08,(0～2.13), 2.37～4.62 mg·kg^(-1) , respectively. EC_(50) values are 13.47～39.12, 6.59～56.18, 372～1034 (mg·kg^(-1)), respectively.NOEC values are 5.62 ～21.41, 0.00～4.53, 133.3～327.1 mg·kg^(-1), respectively. Tangents values of regression equation of the survival of X16 strain in red soil are the maximum ones indicating that REE accumulation in red soil has stronger inhibitory effects than in other two soils. The soil order, reflecting toxic intensity of REE is as follows: red soil>yellow fluovic-aquic soil>yellow cinnamon soil.展开更多
In order to understand the occurrence and development of Semanotus bifasciatus （Motschulsky）, a borer insect of Platycladus orientalis in parts of northern and eastern China and to improve its prediction, the develo...In order to understand the occurrence and development of Semanotus bifasciatus （Motschulsky）, a borer insect of Platycladus orientalis in parts of northern and eastern China and to improve its prediction, the developmental threshold temperature （C1） and effective accumulated temperature （K） of S. bifasciatus were determined under conditions of constant and variable temperatures. The results show that under constant temperatures the value of C1 has a range of 8.90±1.77℃and the value of K lies between 95.19±13.14 degree-day for eggs; the values for larvae are C1= 13.26±3.06℃ and the number of degree-day is K 2,885.07±187.87 degree-day; for pupae the ranges are C1 = 8.93±2.49℃ and K= 131.20±25.63 degree-day. Under the condition of ambient temperatures, the values for eggs are C1= 17.33±1.24℃ and K= 70.79±8.99 degree-day. It is suggested that S. bifasciatus adults over-winter in a state of dormancy, not at a diapause. Warm winter may accelerate the life cycle ofS. bifasciatus. Equations can be used to predict an early occurrence ofS. bifasciatus.展开更多
The objective of this study was to provide reliable basis for decision making for national food security and layout and structure adjustment of grain production in the northeastern China. The data of mean daily air te...The objective of this study was to provide reliable basis for decision making for national food security and layout and structure adjustment of grain production in the northeastern China. The data of mean daily air temperature of 1961-2009 from 106 meteorological stations in the northeastern China were chosen in this study. Using statistical methods and isoline method, the spatio-temporal changes of various decadal ≥10℃accumulated temperature and the climatic means of ≥10℃ accumulated temperature were studied in this paper. The results showed that 1） The geo- graphical distribution of ≥10℃ accumulated temperature in the northeastern China could be influenced directly by the latitude, longitude and altitude. If latitude moved one degree northward, the average decrease amplitude of the climatic means was 101.9℃ in the study area. 2） The means of decadal ≥10℃ accumulated temperature rose since the 1980s, and their increase amplitudes became larger in the 1990s and the 2010s obviously. Compared with those of the 1980s, ≥10℃ accumulated temperature increased by about 100℃ in the mountainous and plain areas in the 1990s; compared with those of the 1990s, ≥10℃ accumulated temperature increased by about 200℃ in the Hulun Buir High Plain and the Songnen Plain, and 100℃ in the Sanjiang Plain and the Liaohe Plain in the 2010s. 3） The means of the decada ≥10℃accumulated temperature for 106 meteorological stations in the northeastern China increased with the rate of 145.57℃/10yr in 1961-2009.4） The climatic means of ≥10℃ accumulated temperature increased from 1961-1990 to 1971-2000 and 1981-2009. Compared with the climatic mean of 1971-2000, that of 1981-2009 had increased by above 50℃ in most of the study area, even up to 156℃. Compared with the climatic mean of 1961-1990, that of 1981-2009 increased by above 100℃ in most parts of the study area, even up to 200℃. 5） The maximum northward shift, eastward and westward extension amplitudes of3100℃, 3300℃ and 3500℃ isolines were larger among all isolines for the climatic means of the three phases. Compared with the positions of the isolines of 1961-1990, those amplitudes of 31000C isoline of 1981-2009 were 145 km, 109 km and 64 km, respectively; those of 3300℃ isoline were 154 km, 54 km and 64 km, respectively; and the maximum northward shift of 3500℃ isoline was about 100 km.展开更多
[Objective] The aim was to study the change trend of accumulated temperature in Shenyang in recent 58 years, as well as its effect on agricultural production. [Method] Based on the surface temperature data in Shenyang...[Objective] The aim was to study the change trend of accumulated temperature in Shenyang in recent 58 years, as well as its effect on agricultural production. [Method] Based on the surface temperature data in Shenyang, the change trends of ≥0 ℃ and ≥10 ℃ accumulated temperature in Shenyang in recent 58 years were analyzed by means of climatic statistics method, and the effects of accumulated temperature variation on agricultural production were discussed. [Result] In recent 58 years, the first day with temperature ≥0 ℃ advanced 10 d, and the last day put off slightly, while sustained days prolonged 13 d, and ≥0 ℃ accumulated temperature increased by 343 ℃·d; meanwhile, the first day with temperature ≥10 ℃ advanced 9 d, and the last day put off 8 d, while sustained days prolonged 16 d, and ≥10 ℃ accumulated temperature increased by 370 ℃·d; compared with the first 20 years, sustained days with temperature ≥0 ℃ and ≥10 ℃ prolonged 9 d in the last 20 years, and ≥0 ℃ and ≥10 ℃ accumulated temperature increased by 196 and 202 ℃·d, respectively. In addition, the increase of heat resources affected agricultural production in Shenyang. [Conclusion] The study could provide theoretical foundation for grasping heat resources variation and adjusting agriculture distribution.展开更多
Global warming has become a topic of widespread attention. The climate change will affect the change of agricultural climate resource,thereby affecting the agricultural planting structure,the grain yield,etc. Based on...Global warming has become a topic of widespread attention. The climate change will affect the change of agricultural climate resource,thereby affecting the agricultural planting structure,the grain yield,etc. Based on the daily temperature of Zhangjiakou from 1960 to 2011,the temporal changes of ≥0 ℃ and ≥10 ℃ accumulated temperatures were analyzed by using the methods of linear trend estimation and M-K mutation test. The results indicated that(1) the annual average temperature showed an increasing trend with the linear warming rate of 0. 42 ℃ /10 a in the past 52 years. In 1982,the annual average temperature had abrupt change,especially after 1983,the warming trend increased significantly.(2) In the past 52 years,≥0 ℃ accumulated temperature showed an increasing trend with the warming rate of 89. 4 ℃ /10 a. Mutation point of ≥0 ℃ accumulated temperature appeared in 1983,and after 1985,≥0 ℃ accumulated temperature increased sharply. At the same time,the ≥10 ℃ accumulated temperature had abrupt change in 1983,especially from 1987 to 1995 and after 1986,the warming trend increased sharply.(3) The initial date of ≥0 ℃ presented significant advancing trend,and that of ≥10 ℃ had little change,while their terminal dates presented delaying trend,so the sustained days of ≥0 ℃ and ≥10 ℃ increased significantly.(4) In the past 52 years,the delay of the terminal dates of ≥0 ℃ and ≥10 ℃ was greater than the advancing of the initial dates,and ≥0 ℃ accumulated temperature had a greater increase than ≥10 ℃ accumulated temperature.展开更多
Modified suction caissons(MSCs)acting as offshore wind turbine foundations will generate the accumulated rotation under cyclic loading resulted from waves.The accumulated rotation and the range of soil deformation aro...Modified suction caissons(MSCs)acting as offshore wind turbine foundations will generate the accumulated rotation under cyclic loading resulted from waves.The accumulated rotation and the range of soil deformation around the MSC under long-term cyclic wave loading were studied using 3-D numerical simulations.The Morison equation was adopted to calculate the wave loadings.It was found that the MSC accumulated rotation increases linearly with the increase of the logarithm of cyclic number.The normalized expression was proposed to reflect the relationship between the accumulated rotation and cyclic number.The soil deformation range around the MSC increases when increasing the cyclic number and loading amplitude.It can also be concluded that the accumulated rotation increases rapidly with this change of excess pore pressure in the first 4000 cycles.The responses of the MSC to wave and wind loads were also investigated.Results show that the accumulated rotation of the MSC under both wave and wind loadings is larger than that under the wave loading only.展开更多
In this study,accumulated extrusion bonding(AEB)process with application of artificial water cooling was successfully performed to fabricate fined-grains AZ31B Mg alloy sheets at 150℃,200℃ and 250℃.The resultant mi...In this study,accumulated extrusion bonding(AEB)process with application of artificial water cooling was successfully performed to fabricate fined-grains AZ31B Mg alloy sheets at 150℃,200℃ and 250℃.The resultant microstructure and mechanical properties are systematically investigated.It reveals that the processing temperature has an important effect on the microstructural evolution during extrusion.During AEB process at 150℃ and 200℃,{10-12}tensile twinning was activated at early stage of extrusion,and subsequently continuous dynamic recrystallization(CDRX)occurred and dominated the further deformation.However,for the sample extruded at 250℃,hardly any twins can be observed,and new fined dynamic recrystallized grains were found along grain boundaries.Artificial cooling was utilized to reduce the rate of grain growth out of the extrusion die,resulting the grains significantly refined from 11μm to 2.5μm.Local high dislocation density region was also observed in the microstructure of sample processed at 150℃ in artificial cooling condition,and the degree decreased with the processing temperature increase.The results summarized from tensile tests indicated that due to the grain refinement the strength and ductility was significantly enhanced(YS of 186 MPa vs.145 MPa,UTS of 391 MPa vs.336 MPa and FE of 31.5%vs.24.5%compared with the as-received sample).Subsequently,annealing treatment at different temperatures was applied to eliminate the high dislocation density.The sample annealed at 200℃ exhibited the best comprehensive mechanical property with YS of 179 MPa,UTS of 390 MPa and FE of 33.0%.As the annealing temperature increasing,the dislocation density was reduced by static recrystallization(SRX)and grain growth,leading to a decreased strength and ductility.展开更多
Laser scanning confocal endomicroscope(LSCEM)has emerged as an imaging modality which provides noninvasive,in vivo imaging of biological tissue on a microscopic scale.Scientific visualizations for LSCEM datasets captu...Laser scanning confocal endomicroscope(LSCEM)has emerged as an imaging modality which provides noninvasive,in vivo imaging of biological tissue on a microscopic scale.Scientific visualizations for LSCEM datasets captured by current imaging systems require these datasets to be fully acquired and brought to a separate rendering machine.To extend the features and capabilities of this modality,we propose a system which is capable of performing realtime visualization of LSCEM datasets.Using field-programmable gate arrays,our system performs three tasks in parallel:(1)automated control of dataset acquisition;(2)imaging-rendering system synchronization;and(3)realtime volume rendering of dynamic datasets.Through fusion of LSCEM imaging and volume rendering processes,acquired datasets can be visualized in realtime to provide an immediate perception of the image quality and biological conditions of the subject,further assisting in realtime cancer diagnosis.Subsequently,the imaging procedure can be improved for more accurate diagnosis and reduce the need for repeating the process due to unsatisfactory datasets.展开更多
The personal account of new rural social pension insurance raises funds in the form of individual premium-paying,collectively pooled subsidy and government subsidy.The personal account accumulated value has a decisive...The personal account of new rural social pension insurance raises funds in the form of individual premium-paying,collectively pooled subsidy and government subsidy.The personal account accumulated value has a decisive influence on the payment level of personal account pension.The personal account accumulated value has a direct or indirect relationship with the income level of farmers,premium-paying level,the insured period,investment return rate of funds and other factors.Analysing the impact of infinitesimal variation of these factors on accumulated value of personal account pension,is of great significance to improving and consolidating personal account,and achieving sustainable development of new rural social pension insurance.展开更多
AZ31 Mg alloy with heterogeneous bimodal grain structure(smaller grain size of 5-20µm and coarser grain size of 100-200µm)was subjected to accumulated extrusion bonding(AEB)at 250℃combined with two-stage ar...AZ31 Mg alloy with heterogeneous bimodal grain structure(smaller grain size of 5-20µm and coarser grain size of 100-200µm)was subjected to accumulated extrusion bonding(AEB)at 250℃combined with two-stage artificial cooling in this work,viz.local water cooling and artificial cooling.The microstructure developed consecutively as a result of discontinuous dynamic recrystallization(DDRX)for the AEBed samples.{10-12}tensile twinning also played an important role for the AEB with local water cooling at the initial extrusion stage in the container.Local water cooling could further reduce the DRXed grain size to~2.1µm comparing that without water cooling.And the grain growth rate was reduced by artificial cooling out of extrusion die.Under the combination of two-stage cooling,the fine DRXed grains at sizing band were almost retained with average grain size of~2.3µm after the sheet out of extrusion die,and the unDRXed grains with high residual dislocation density accumulation were also reserved.The tensile tests results indicated that a good strength-ductility balance with a high ultimate tensile strength(319 MPa vs.412 MPa)and fracture elongation(19.9%vs.30.3%)were obtained.The strength enhancement was mainly owing to the grain refinement and local residual plastic strain reserved by the artificial cooling.The excellent ductility originated from fine DRXed microstructure and ED-tilt double peak texture.展开更多
Based on dynamic triaxial test results of saturated soft clay, similarities of variations between accumulated pore water pressure and accumulated deformation were analyzed. The Parr＇s equation on accumulated deformat...Based on dynamic triaxial test results of saturated soft clay, similarities of variations between accumulated pore water pressure and accumulated deformation were analyzed. The Parr＇s equation on accumulated deformation was modified to create an attenuation-type curve model on accumulated pore water pressure in saturated normal consolidation clay. In this model, dynamic strength was introduced and a new parameter called equivalent dynamic stress level was added. Besides, based on comparative analysis on variations between failure-type and attenuatiun-type curves, a failure-type curve model was created on accumulated pore water pressure in saturated normal consolidation clay. Two models can take cycle number, coupling of static and dynamic deviator stress, and consolidation way into consideration. The models are verified by test results. The correlation coefficients are more than 0.98 for optimization of test results based on the two models, and there is good agreement between the optimized and test curves, which shows that the two models are suitable to predict variations of accumulated pore water pressure under different loading cases and consolidation ways. In order to improve prediction accuracy, it is suggested that loading cases and consolidation ways should be consistent with in-situ conditions when dynamic triaxial tests are used to determine the constants in the models.展开更多
文摘To determine the effects of preharvest arginine spraying on the nutritional level of broccoli and the mechanism of action of arginine in improving the storage quality of broccoli,arginine spraying(5 mmol/L)was conducted at 0,1,3,and 5 days before harvest.The appearance,respiration rate,mass-loss rate,electrolyte leakage,glucosinolate,ascorbic acid,total phenol,total flavonoid,total sugar and sucrose contents,and sucrose phosphate synthase(SPS),invertase(INV),sucrose synthase synthesis(SSS)and cleavage(SSC)activities of broccoli samples were observed after 0,2,4,6,8,and 10 days of storage.The results showed that spraying arginine at 5 days preharvest(5-ARG)helped to inhibit broccoli respiration during storage,delay electrolyte leakage,and maintain broccoli color.Furthermore,during the growth stage,total sugar accumulation was higher in the 5-ARG group.In addition,during the storage period,sucrose synthesis was accelerated,while sucrose cleavage was inhibited,resulting in more sucrose retention in postharvest broccoli.In conclusion,5-ARG resulted in the accumulation of more nutrients during the growth process and effectively delayed the quality decline during storage,thereby prolonging the shelf life of broccoli.Therefore,this study provides a theoretical basis for improving postharvest storage characteristics of broccoli through preharvest treatments.
基金the National Key Research and Development Program of China(2022YFD1500705)National Natural Science Foundation of China(U19A2035)for financial support。
文摘Strip-till(ST),including straw mulching in the inter-row and localized fertilization in the intra-row,is a conservation tillage system for improving soil quality and crop growth.However,the yield advantage of maize under ST compared to conventional tillage(CT)remains unstable,and the strategies to increase maize yield under ST are unclear.This study aims to understand the physiological mechanism underlining maize yield formation under ST by comparing two maize cultivars,DKM753 and DK517,with contrasting yield performance in ST versus CT systems.Compared to CT,ST resulted in a 4.5%yield increase for DKM753 but a 5.6%decrease for DK517.These yield differences were primarily attributed to variations in grain number per ear(GN).During the rapid growth stage(V14-R3),i.e.,two weeks before and after silking,DKM753 showed a 6.7%increase in maximum growth rate(V_(max))and a 6.3%increase in average growth rate(V)under ST,whereas DK517 exhibited decline of 8.5%in V_(max) and 12.3%in V.Significant positive correlations are observed between V_(max) and V with GN under ST(R^(2)=0.79 and R^(2)=0.90,respectively).Enhanced dry matter accumulation in DKM753 under ST was attributed to increased leaf expansion rates,contributing to a larger photosynthate source.The straw mulching and localized nitrogen fertilization increased root-zone nitrogen availability at silking in ST compared to CT.DKM753 had a greater root system which made better use of the soil N and lead to an increased leaf nitrogen accumulation by 14.9%under ST.It is concluded that maize yield under the strip-till system is determined by grain number per ear,which can be increased by increasing nitrogen accumulation,plant growth,and ear development around silking stage.A sound root system can efficiently utilize soil nitrogen resources under the strip-till system,increasing plant nitrogen accumulation and thereby promoting plant growth.
基金financially supported by the Science and Technology Innovation Foundation of the Command Center of Integrated Natural Resources Survey Center(KC20230002)the China Geological Survey Project(DD20230471,DD20220855 and DD20243282)+1 种基金the National Natural Science Foundation of China(41872100)the National Key R&D Plan(2022YFC2903402)。
文摘Black soil is essential for maintaining regional food security and promoting global agricultural production.Understanding the weathering process of parent material and the accumulation of organic carbon is crucial to comprehending the developmental history and future trends of black soil,especially against the background of large-scale global cultivation and climate change.Although the importance of black soil formation and evolution cannot be ignored,the relevant research is still very scarce.In this study,a typical eight-meter-deep soil core was collected from the Keshan area of the Songnen Plain,Northeast China,where surface black soil developed on paleo-sediments.Using^(14)C dating,the formation age of the black soil was determined.Based on the characteristics of the geochemical composition,grain size and the magnetic susceptibility of the sediments,it was demonstrated that the black soil and its parent material originated from reworked loess.Furthermore,the mass transfer coefficient(τ)of some elements was determined,in order to explore the soil weathering process.By calculating the transported amount of alkaline and alkaline-earth elements,the weathering rate of parent material to black soil was found to be weak,at 0.16 kEq·ha^(-1)·year^(-1).Combining the results of dating and carbon density in the different layers of black soil,the accumulation rate of organic carbon was determined as follows:rapidly increasing in the initial period of 13.2-2.2 ka,reaching its maximum average value of 34.0 g·cm^(-2)·a^(-1)at 2.2-0.8 ka,then showing a decreasing trend with an average value of-77.5 g·cm^(-2)·a^(-1).Compared with regional climate change,Keshan black soil has developed under a colder and wetter climate during the Holocene.Predictably,ongoing global warming may lead to the degradation of black soils in the Songnen Plain,as well as in other regions.Our results will enrich geological knowledge of black soil formation and future evolutionary trends.
基金Supported by the Research Project of CNOOC(KJZH-2021-0003-00).
文摘Based on petroleum exploration and new progress of oil and gas geology study in the Qiongdongnan Basin,combined with seismic,logging,drilling,core,sidewall coring,geochemistry data,a systematic study is conducted on the source,reservoir-cap conditions,trap types,migration and accumulation characteristics,enrichment mechanisms,and reservoir formation models of ultra-deep water and ultra-shallow natural gas,taking the Lingshui 36-1 gas field as an example.(1)The genetic types of the ultra-deep water and ultra-shallow natural gas in the Qiongdongnan Basin include thermogenic gas and biogenic gas,and dominated by thermogenic gas.(2)The reservoirs are mainly composed of the Quaternary deep-water submarine fan sandstone.(3)The types of cap rocks include deep-sea mudstone,mass transport deposits mudstone,and hydrate-bearing formations.(4)The types of traps are mainly lithological,and also include structural-lithological traps.(5)The migration channels include vertical transport channels such as faults,gas chimneys,fracture zones,and lateral transport layers such as large sand bodies and unconformity surfaces,forming a single or composite transport framework.A new natural gas accumulation model is proposed for ultra-deep water and ultra-shallow layers,that is,dual source hydrocarbon supply,gas chimney and submarine fan composite migration,deep-sea mudstone-mass transport deposits mudstone-hydrate-bearing strata ternary sealing,late dynamic accumulation,and large-scale enrichment at ridges.The new understanding obtained from the research has reference and enlightening significance for the next step of deepwater and ultra-shallow layers,as well as oil and gas exploration in related fields or regions.
基金Supported by the PetroChina Basic Project(2024DJ23)CNPC Science Research and Technology Development Project(2021DJ0101)。
文摘Coal measures are significant hydrocarbon source rocks and reservoirs in petroliferous basins.Many large gas fields and coalbed methane fields globally are originated from coal-measure source rocks or accumulated in coal rocks.Inspired by the discovery of shale oil and gas,and guided by“the overall exploration concept of considering coal rock as reservoir”,breakthroughs in the exploration and development of coal-rock gas have been achieved in deep coal seams with favorable preservation conditions,thereby opening up a new development frontier for the unconventional gas in coal-rock reservoirs.Based on the data from exploration and development practices,a systematic study on the accumulation mechanism of coal-rock gas has been conducted.The mechanisms of“three fields”controlling coal-rock gas accumulation are revealed.It is confirmed that the coal-rock gas is different from CBM in accumulation process.The whole petroleum systems in the Carboniferous–Permian transitional facies coal measures of the eastern margin of the Ordos Basin and in the Jurassic continental facies coal measures of the Junggar Basin are characterized,and the key research directions for further developing the whole petroleum system theory of coal measures are proposed.Coal rocks,compared to shale,possess intense hydrocarbon generation potential,strong adsorption capacity,dual-medium reservoir properties,and partial or weak oil and gas self-sealing capacity.Additionally,unlike other unconventional gas such as shale gas and tight gas,coal-rock gas exhibits more complex accumulation characteristics,and its accumulation requires a certain coal-rock play form lithological and structural traps.Coal-rock gas also has the characteristics of conventional fractured gas reservoirs.Compared with the basic theory and model of the whole petroleum system established based on detrital rock formations,coal measures have distinct characteristics and differences in coal-rock reservoirs and source-reservoir coupling.The whole petroleum system of coal measures is composed of various types of coal-measure hydrocarbon plays with coal(and dark shale)in coal measures as source rock and reservoir,and with adjacent tight layers as reservoirs or cap or transport layers.Under the action of source-reservoir coupling,coal-rock gas is accumulated in coal-rock reservoirs with good preservation conditions,tight oil/gas is accumulated in tight layers,conventional oil/gas is accumulated in traps far away from sources,and coalbed methane is accumulated in coal-rock reservoirs damaged by later geological processes.The proposed whole petroleum system of coal measures represents a novel type of whole petroleum system.
基金Supported by Project for NewTechnology Generalization of China Meteorological Administration(CMATG2007M37)~~
文摘According to phenological observation data of fourteen stations in Hunan,Hubei and Jiangxi provinces from 1994 to 2006,indices of suitable temperature at the booting stage and accumulated temperature(≥10 ℃)during the whole growth period in early or late rice in the south of China were analyzed by statistics and biological relationship between factors.Indices of the optimum daily mean temperature and the minimum temperature at the booting stage were as follows:Early convention rice variety was 25.7 ℃ and 22.3 ℃ respectively,hybrid variety was 26.5 ℃ and 23.3℃ respectively;while late convention rice variety was 25.6 ℃ and 22.3 ℃ respectively,hybrid variety was 25.8 ℃ and 22.6 ℃ respectively.Indexes of accumulated temperature during the whole growth period were as follows:The early-maturing variety,the middle-maturing variety and the late-maturing variety of early rice was 2 512.1 ℃,2 528.4 ℃ and 2 651.3 ℃ respectively,while the early-maturing variety,the middle-maturing variety and the late-maturing variety of late rice was 3 126.2 ℃,3 031.5 ℃ and 3 335.2 ℃ respectively.The above indexes all met the requirements of identification,which could provide reference for formulating the meteorological standard of rice in the south of China.
基金Supported by Tianjin University of Science & Technology LaboratoryOpen Fund(1014A109)National 863 Science Plan(2010AA101301)National Natural Science Foundation(20903071)~~
文摘[Objective]The research aimed at constructing an accumulated temperature effect model for fertility alteration of two-line hybrid rice P88S.[Method]Analyze the experiment datas of fertility alteration of P88S in Hainan from 2005 to 2006.[Result]The fertilities of P88S with temperatures ranging from 26 to 28 ℃ were determined by the absolute values and the accumulation effects of the temperature.An accumulation effect model of temperatures based on the bistable state was obtained.[Conclusion]The temperature asymmetry of fertility alteration for two-line sterility line in spring and autumn can be elucidated effectively using the accumulated temperature effect model,namely,alternating from fertile to sterile requires higher temperatures,and alternating from sterile to fertile requires lower temperatures.
基金supported by the grants from the Agricultural Science and Technology Innovation Program, China (CAAS-ASTIP-2015-ZFRI)the Comprehensive Experimental Station of Zhengzhou of China Agriculture Research System (CARS-31-Z-10)
文摘Winter chill is essential for the growth and development of deciduous species. To understand the relationship between accumulated chilling hours during endodormancy and blooming and fruit shape development, we controlled chilling hours and investigated their effects on blooming date and fruit shape of peaches. The results showed that the number of days to full bloom date and the heat requirement for blooming were negatively correlated with accumulated chilling hours. Accumulated chilling hours were significantly negatively correlated with fruit shape index and fruit tip lengths, suggesting that the number of chilling hours affect the fruit shape development. Fewer accumulated chilling hours may be the major reason for longer fruit shape and protruding fruit tips. In conclusion, our results indicate specifically that decreased winter chilling hours can delay the bloom date and may lead to aberrant fruit shape development in peaches. Our study provides preliminary insights into the response of temperate fruit species to global climate change.
基金National Key Basic Research Support Foundation of China(No.G1999011807)the National Natural Science Foundation of China(No.39500086).
文摘Profile characteristics of accumulated P in 10 representativesoils of vegetable fields in suburban districts of Beijing wereinvestigated. Bioavailability of the accumulated P and its potentialeffect n the environment were studied in a greenhouse pot experimentand a soil column experiment. The results showed that theconcentration of Olsen-P in the 0～20 cm soil samples of thevegetable fields ranged from 2.1 to 358.0 mg kg^-1, which was 2 to 10times higher than that of the crop field sin the suburbs of Beijing.Most of the excessive phosphorus was accumulated in the topsoils.
文摘Rare earth elements(REE)are applied as micro-fertilizer in large scale in China and there is growing concern about the environmental effects of REE accumulation in soils. Accumulation of REE was simulated in lab by adding REE to three soils and the survival of Pseudomonas fluorescence X16 strain marked with luxAB gene in soils was detected. Curvilinear regression method was applied to analyze the survival pattern. The stimulation values, EC_(50) and NOEC values for X16 strain were calculated to compare the toxic intensity of REE in different soils. The stimulation(peak)values in red soil, yellow fluovo-aquic soil and yellow cinnamon soil, are 11.55～18.08,(0～2.13), 2.37～4.62 mg·kg^(-1) , respectively. EC_(50) values are 13.47～39.12, 6.59～56.18, 372～1034 (mg·kg^(-1)), respectively.NOEC values are 5.62 ～21.41, 0.00～4.53, 133.3～327.1 mg·kg^(-1), respectively. Tangents values of regression equation of the survival of X16 strain in red soil are the maximum ones indicating that REE accumulation in red soil has stronger inhibitory effects than in other two soils. The soil order, reflecting toxic intensity of REE is as follows: red soil>yellow fluovic-aquic soil>yellow cinnamon soil.
文摘In order to understand the occurrence and development of Semanotus bifasciatus （Motschulsky）, a borer insect of Platycladus orientalis in parts of northern and eastern China and to improve its prediction, the developmental threshold temperature （C1） and effective accumulated temperature （K） of S. bifasciatus were determined under conditions of constant and variable temperatures. The results show that under constant temperatures the value of C1 has a range of 8.90±1.77℃and the value of K lies between 95.19±13.14 degree-day for eggs; the values for larvae are C1= 13.26±3.06℃ and the number of degree-day is K 2,885.07±187.87 degree-day; for pupae the ranges are C1 = 8.93±2.49℃ and K= 131.20±25.63 degree-day. Under the condition of ambient temperatures, the values for eggs are C1= 17.33±1.24℃ and K= 70.79±8.99 degree-day. It is suggested that S. bifasciatus adults over-winter in a state of dormancy, not at a diapause. Warm winter may accelerate the life cycle ofS. bifasciatus. Equations can be used to predict an early occurrence ofS. bifasciatus.
基金Under the auspices of National Natural Science Foundation of China (No. 40771190)Special Fund for Meteorological Scientific Research in the Public Interest (No. GYHY200706030)
文摘The objective of this study was to provide reliable basis for decision making for national food security and layout and structure adjustment of grain production in the northeastern China. The data of mean daily air temperature of 1961-2009 from 106 meteorological stations in the northeastern China were chosen in this study. Using statistical methods and isoline method, the spatio-temporal changes of various decadal ≥10℃accumulated temperature and the climatic means of ≥10℃ accumulated temperature were studied in this paper. The results showed that 1） The geo- graphical distribution of ≥10℃ accumulated temperature in the northeastern China could be influenced directly by the latitude, longitude and altitude. If latitude moved one degree northward, the average decrease amplitude of the climatic means was 101.9℃ in the study area. 2） The means of decadal ≥10℃ accumulated temperature rose since the 1980s, and their increase amplitudes became larger in the 1990s and the 2010s obviously. Compared with those of the 1980s, ≥10℃ accumulated temperature increased by about 100℃ in the mountainous and plain areas in the 1990s; compared with those of the 1990s, ≥10℃ accumulated temperature increased by about 200℃ in the Hulun Buir High Plain and the Songnen Plain, and 100℃ in the Sanjiang Plain and the Liaohe Plain in the 2010s. 3） The means of the decada ≥10℃accumulated temperature for 106 meteorological stations in the northeastern China increased with the rate of 145.57℃/10yr in 1961-2009.4） The climatic means of ≥10℃ accumulated temperature increased from 1961-1990 to 1971-2000 and 1981-2009. Compared with the climatic mean of 1971-2000, that of 1981-2009 had increased by above 50℃ in most of the study area, even up to 156℃. Compared with the climatic mean of 1961-1990, that of 1981-2009 increased by above 100℃ in most parts of the study area, even up to 200℃. 5） The maximum northward shift, eastward and westward extension amplitudes of3100℃, 3300℃ and 3500℃ isolines were larger among all isolines for the climatic means of the three phases. Compared with the positions of the isolines of 1961-1990, those amplitudes of 31000C isoline of 1981-2009 were 145 km, 109 km and 64 km, respectively; those of 3300℃ isoline were 154 km, 54 km and 64 km, respectively; and the maximum northward shift of 3500℃ isoline was about 100 km.
基金Supported by Scientific Research Project of Shenyang Science and Technology Bureau([2010]Number 15)
文摘[Objective] The aim was to study the change trend of accumulated temperature in Shenyang in recent 58 years, as well as its effect on agricultural production. [Method] Based on the surface temperature data in Shenyang, the change trends of ≥0 ℃ and ≥10 ℃ accumulated temperature in Shenyang in recent 58 years were analyzed by means of climatic statistics method, and the effects of accumulated temperature variation on agricultural production were discussed. [Result] In recent 58 years, the first day with temperature ≥0 ℃ advanced 10 d, and the last day put off slightly, while sustained days prolonged 13 d, and ≥0 ℃ accumulated temperature increased by 343 ℃·d; meanwhile, the first day with temperature ≥10 ℃ advanced 9 d, and the last day put off 8 d, while sustained days prolonged 16 d, and ≥10 ℃ accumulated temperature increased by 370 ℃·d; compared with the first 20 years, sustained days with temperature ≥0 ℃ and ≥10 ℃ prolonged 9 d in the last 20 years, and ≥0 ℃ and ≥10 ℃ accumulated temperature increased by 196 and 202 ℃·d, respectively. In addition, the increase of heat resources affected agricultural production in Shenyang. [Conclusion] The study could provide theoretical foundation for grasping heat resources variation and adjusting agriculture distribution.
文摘Global warming has become a topic of widespread attention. The climate change will affect the change of agricultural climate resource,thereby affecting the agricultural planting structure,the grain yield,etc. Based on the daily temperature of Zhangjiakou from 1960 to 2011,the temporal changes of ≥0 ℃ and ≥10 ℃ accumulated temperatures were analyzed by using the methods of linear trend estimation and M-K mutation test. The results indicated that(1) the annual average temperature showed an increasing trend with the linear warming rate of 0. 42 ℃ /10 a in the past 52 years. In 1982,the annual average temperature had abrupt change,especially after 1983,the warming trend increased significantly.(2) In the past 52 years,≥0 ℃ accumulated temperature showed an increasing trend with the warming rate of 89. 4 ℃ /10 a. Mutation point of ≥0 ℃ accumulated temperature appeared in 1983,and after 1985,≥0 ℃ accumulated temperature increased sharply. At the same time,the ≥10 ℃ accumulated temperature had abrupt change in 1983,especially from 1987 to 1995 and after 1986,the warming trend increased sharply.(3) The initial date of ≥0 ℃ presented significant advancing trend,and that of ≥10 ℃ had little change,while their terminal dates presented delaying trend,so the sustained days of ≥0 ℃ and ≥10 ℃ increased significantly.(4) In the past 52 years,the delay of the terminal dates of ≥0 ℃ and ≥10 ℃ was greater than the advancing of the initial dates,and ≥0 ℃ accumulated temperature had a greater increase than ≥10 ℃ accumulated temperature.
基金the National Natural Science Foundation of China(Grant Nos.51639002,51879044 and 51808325)SDUST(Shandong University of Science and Technology)Research Fund(Grant No.2015KYTD104).
文摘Modified suction caissons(MSCs)acting as offshore wind turbine foundations will generate the accumulated rotation under cyclic loading resulted from waves.The accumulated rotation and the range of soil deformation around the MSC under long-term cyclic wave loading were studied using 3-D numerical simulations.The Morison equation was adopted to calculate the wave loadings.It was found that the MSC accumulated rotation increases linearly with the increase of the logarithm of cyclic number.The normalized expression was proposed to reflect the relationship between the accumulated rotation and cyclic number.The soil deformation range around the MSC increases when increasing the cyclic number and loading amplitude.It can also be concluded that the accumulated rotation increases rapidly with this change of excess pore pressure in the first 4000 cycles.The responses of the MSC to wave and wind loads were also investigated.Results show that the accumulated rotation of the MSC under both wave and wind loadings is larger than that under the wave loading only.
基金the National Natural Science Foundation of China(No.51905366,51901149,51671041,51604181,U1910213 and U1610253)the Key Research and Development Program of Shanxi Province(No.201603D111004)+1 种基金the Fund for Shanxi“1331 Project”Key Subjects Construction,Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0632)Taiyuan University of Science and Technology Scientific Research Initial Funding(20182030,20192003 and 20192008)。
文摘In this study,accumulated extrusion bonding(AEB)process with application of artificial water cooling was successfully performed to fabricate fined-grains AZ31B Mg alloy sheets at 150℃,200℃ and 250℃.The resultant microstructure and mechanical properties are systematically investigated.It reveals that the processing temperature has an important effect on the microstructural evolution during extrusion.During AEB process at 150℃ and 200℃,{10-12}tensile twinning was activated at early stage of extrusion,and subsequently continuous dynamic recrystallization(CDRX)occurred and dominated the further deformation.However,for the sample extruded at 250℃,hardly any twins can be observed,and new fined dynamic recrystallized grains were found along grain boundaries.Artificial cooling was utilized to reduce the rate of grain growth out of the extrusion die,resulting the grains significantly refined from 11μm to 2.5μm.Local high dislocation density region was also observed in the microstructure of sample processed at 150℃ in artificial cooling condition,and the degree decreased with the processing temperature increase.The results summarized from tensile tests indicated that due to the grain refinement the strength and ductility was significantly enhanced(YS of 186 MPa vs.145 MPa,UTS of 391 MPa vs.336 MPa and FE of 31.5%vs.24.5%compared with the as-received sample).Subsequently,annealing treatment at different temperatures was applied to eliminate the high dislocation density.The sample annealed at 200℃ exhibited the best comprehensive mechanical property with YS of 179 MPa,UTS of 390 MPa and FE of 33.0%.As the annealing temperature increasing,the dislocation density was reduced by static recrystallization(SRX)and grain growth,leading to a decreased strength and ductility.
文摘Laser scanning confocal endomicroscope(LSCEM)has emerged as an imaging modality which provides noninvasive,in vivo imaging of biological tissue on a microscopic scale.Scientific visualizations for LSCEM datasets captured by current imaging systems require these datasets to be fully acquired and brought to a separate rendering machine.To extend the features and capabilities of this modality,we propose a system which is capable of performing realtime visualization of LSCEM datasets.Using field-programmable gate arrays,our system performs three tasks in parallel:(1)automated control of dataset acquisition;(2)imaging-rendering system synchronization;and(3)realtime volume rendering of dynamic datasets.Through fusion of LSCEM imaging and volume rendering processes,acquired datasets can be visualized in realtime to provide an immediate perception of the image quality and biological conditions of the subject,further assisting in realtime cancer diagnosis.Subsequently,the imaging procedure can be improved for more accurate diagnosis and reduce the need for repeating the process due to unsatisfactory datasets.
基金Supported by Scientific Research Project of Hunan Provincial Department of Education(11C1180)
文摘The personal account of new rural social pension insurance raises funds in the form of individual premium-paying,collectively pooled subsidy and government subsidy.The personal account accumulated value has a decisive influence on the payment level of personal account pension.The personal account accumulated value has a direct or indirect relationship with the income level of farmers,premium-paying level,the insured period,investment return rate of funds and other factors.Analysing the impact of infinitesimal variation of these factors on accumulated value of personal account pension,is of great significance to improving and consolidating personal account,and achieving sustainable development of new rural social pension insurance.
基金The authors are grateful for the National Natural Science Foundation of China(No.51905366 and U1810122)Yantai high-end talent introduction"Double Hundred Plan"(2021)Key Research and Development Program of Shanxi Province(201903D421076).
文摘AZ31 Mg alloy with heterogeneous bimodal grain structure(smaller grain size of 5-20µm and coarser grain size of 100-200µm)was subjected to accumulated extrusion bonding(AEB)at 250℃combined with two-stage artificial cooling in this work,viz.local water cooling and artificial cooling.The microstructure developed consecutively as a result of discontinuous dynamic recrystallization(DDRX)for the AEBed samples.{10-12}tensile twinning also played an important role for the AEB with local water cooling at the initial extrusion stage in the container.Local water cooling could further reduce the DRXed grain size to~2.1µm comparing that without water cooling.And the grain growth rate was reduced by artificial cooling out of extrusion die.Under the combination of two-stage cooling,the fine DRXed grains at sizing band were almost retained with average grain size of~2.3µm after the sheet out of extrusion die,and the unDRXed grains with high residual dislocation density accumulation were also reserved.The tensile tests results indicated that a good strength-ductility balance with a high ultimate tensile strength(319 MPa vs.412 MPa)and fracture elongation(19.9%vs.30.3%)were obtained.The strength enhancement was mainly owing to the grain refinement and local residual plastic strain reserved by the artificial cooling.The excellent ductility originated from fine DRXed microstructure and ED-tilt double peak texture.
基金Project(2009AA11Z101) supported by National High Technology Research and Development Program of ChinaProject supported by Postdoctoral Science Foundation of Central South University,China+1 种基金Project(2012QNZT045) supported by Fundamental Research Funds for Central Universities of ChinaProject(2011CB710601) supported by the National Basic Research Program of China
文摘Based on dynamic triaxial test results of saturated soft clay, similarities of variations between accumulated pore water pressure and accumulated deformation were analyzed. The Parr＇s equation on accumulated deformation was modified to create an attenuation-type curve model on accumulated pore water pressure in saturated normal consolidation clay. In this model, dynamic strength was introduced and a new parameter called equivalent dynamic stress level was added. Besides, based on comparative analysis on variations between failure-type and attenuatiun-type curves, a failure-type curve model was created on accumulated pore water pressure in saturated normal consolidation clay. Two models can take cycle number, coupling of static and dynamic deviator stress, and consolidation way into consideration. The models are verified by test results. The correlation coefficients are more than 0.98 for optimization of test results based on the two models, and there is good agreement between the optimized and test curves, which shows that the two models are suitable to predict variations of accumulated pore water pressure under different loading cases and consolidation ways. In order to improve prediction accuracy, it is suggested that loading cases and consolidation ways should be consistent with in-situ conditions when dynamic triaxial tests are used to determine the constants in the models.
