The impact of anomalous sea surface temperature (SST) warming in the Kuroshio Extension in the previous winter on the East Asian summer monsoon (EASM) was investigated by performing simulation tests using NCAR CAM3.Th...The impact of anomalous sea surface temperature (SST) warming in the Kuroshio Extension in the previous winter on the East Asian summer monsoon (EASM) was investigated by performing simulation tests using NCAR CAM3.The results show that anomalous SST warming in the Kuroshio Extension in winter causes the enhancement and northward movement of the EASM.The monsoon indexes for East Asian summer monsoon and land-sea thermal difference,which characterize the intensity of the EASM,show an obvious increase during the onset period of the EASM.Moreover,the land-sea thermal difference is more sensitive to warmer SST.Low-level southwesterly monsoon is clearly strengthened meanwhile westerly flows north (south) of the subtropical westerly jet axis are strengthened (weakened) in northern China,South China Sea,and the Western Pacific Ocean to the east of the Philippines.While there is an obvious decrease in precipitation over the Japanese archipelago and adjacent oceans and over the area from the south of the Yangtze River in eastern China to the Qinling Mountains in southern China,precipitation increases notably in northern China,the South China Sea,the East China Sea,the Yellow Sea,and the Western Pacific to the east of the Philippines.North China is the key area where the response of the EASM to the SST anomalous warming in the Kuroshio Extension is prominent.The surface air temperature shows a warming trend.The warming in the entire troposphere between 30oN and 50oN increases the land-sea thermal contrast,which plays an important role in the enhancement of the EASM.Atmospheric circulation and precipitation anomalies in China and its adjacent regions have a close relationship with the enhancement of the Western Pacific subtropical high and its northward extension.展开更多
Ecosystems in high-altitude regions are more sensitive and respond more rapidly than other ecosystems to global climate warming.The Qinghai-Tibet Plateau(QTP)of China is an ecologically fragile zone that is sensitive ...Ecosystems in high-altitude regions are more sensitive and respond more rapidly than other ecosystems to global climate warming.The Qinghai-Tibet Plateau(QTP)of China is an ecologically fragile zone that is sensitive to global climate warming.It is of great importance to study the changes in aboveground biomass and species diversity of alpine meadows on the QTP under predicted future climate warming.In this study,we selected an alpine meadow on the QTP as the study object and used infrared radiators as the warming device for a simulation experiment over eight years(2011-2018).We then analyzed the dynamic changes in aboveground biomass and species diversity of the alpine meadow at different time scales,including an early stage of warming(2011-2013)and a late stage of warming(2016-2018),in order to explore the response of alpine meadows to short-term(three years)and long-term warming(eight years).The results showed that the short-term warming increased air temperature by 0.31℃and decreased relative humidity by 2.54%,resulting in the air being warmer and drier.The long-term warming increased air temperature and relative humidity by 0.19℃and 1.47%,respectively,and the air tended to be warmer and wetter.The short-term warming increased soil temperature by 2.44℃and decreased soil moisture by 12.47%,whereas the long-term warming increased soil temperature by 1.76℃and decreased soil moisture by 9.90%.This caused the shallow soil layer to become warmer and drier under both short-term and long-term warming.Furthermore,the degree of soil drought was alleviated with increased warming duration.Under the long-term warming,the importance value and aboveground biomass of plants in different families changed.The importance values of grasses and sedges decreased by 47.56%and 3.67%,respectively,while the importance value of weeds increased by 1.37%.Aboveground biomass of grasses decreased by 36.55%,while those of sedges and weeds increased by 8.09%and 15.24%,respectively.The increase in temperature had a non-significant effect on species diversity.The species diversity indices increased at the early stage of warming and decreased at the late stage of warming,but none of them reached significant levels(P>0.05).Species diversity had no significant correlation with soil temperature and soil moisture under both short-term and long-term warming.Soil temperature and aboveground biomass were positively correlated in the control plots(P=0.014),but negatively correlated under the long-term warming(P=0.013).Therefore,eight years of warming aggravated drought in the shallow soil layer,which is beneficial for the growth of weeds but not for the growth of grasses.Warming changed the structure of alpine meadow communities and had a certain impact on the community species diversity.Our studies have great significance for the protection and effective utilization of alpine vegetation,as well as for the prevention of grassland degradation or desertification in high-altitude regions.展开更多
The content of organic matter (OM), nitrogen (N), phosphorus (P), and potassium (K) in the three selected soils, including Calcaric Purpli-Orthic Primosols (purple sand-shale parent material), Dystric Turbi-...The content of organic matter (OM), nitrogen (N), phosphorus (P), and potassium (K) in the three selected soils, including Calcaric Purpli-Orthic Primosols (purple sand-shale parent material), Dystric Turbi-Anthric Primosols (quaternary red clay parent material) and Typic Udi-Sandic Primosols (granite parent material) were studied under a long-term experiment by using crop straw and inorganic fertilizers at the Hunan Red Soil Experiment Station of Chinese Academy of Agricultural Sciences. The results showed that the contents of OM, N, P and K in the three selected soils increased after 23 years application of crop straw and inorganic fertilizers, but the contents increased much less when crop straw or inorganic fertilizers was applied alone. The nutrient contents in the three soils developed from granite changed more remarkably than those in the soil derived from quaternary red clay and purple sand-shale. It was also found that the contents of OM, N, and P increased slightly in the treatments without applying fertilizers or returning the crop straw to the root bed. Combined application of inorganic fertilizers and crop straw could remarkably increase the contents of OM, alkalihydrolyzable N and available K, the positive correlation between application of organic fertilizers and increase of OM in soil did not always happened, it provided evidence for the relation between appropriate C/N ratio and accumulation of OM in soil. The increase of nutrient content was influenced by the soil properties. By comparing the contents of nutrient in 0-20 cm depth in the three different soils, it was concluded that the most increases of OM, alkali-hydrolyzable N, and available P were observed in Typic Udi-Sandic Primosols with the average increase by 3.03, 27.38, and 21.73 mg kg^-1, respectively. The available K increased in Dystric Turbi-Anthric Primosols with the average increase by 25.82 mg kg^-1, while it decreased in Calcaric Purpli-Orthic Primosols and Typic Udi-Sandic Primosols. It was concluded that the application of inorganic fertilizer and crop straw was important to improve the soil fertility for all of three selected soils. The straw return to the field had played a significant role for enhancement of the soil quality in the study areas. The application of inorganic fertilizer combined with the straw return to the fields could remarkably improve the soil fertility.展开更多
A long-term fertilization experiment was set up in northern Xinjiang, China to evaluate the dynamics of crop production and soil organic carbon (SOC) from 1990 to 2012 with seven fertilization treatments. The seven ...A long-term fertilization experiment was set up in northern Xinjiang, China to evaluate the dynamics of crop production and soil organic carbon (SOC) from 1990 to 2012 with seven fertilization treatments. The seven treatments included an unfertilized control (CK) and six different combinations of phosphorus (P), potassium (K), nitrogen (N), straw (S) and animal manure (M). The balanced fertilization treatments had significantly (P〈0.05) higher average yields than the unbalanced ones. The treatment with 2/3 N from potassium sulfate (NPK) and 1/3 N from farmyard manure (NPKM) had a higher average yield than the other treatments. The average yields (over the 23 years) in the treatments of NPK, and urea, calcium superphosphate (NP) did not differ significantly (P〉0.05) but were higher than that in the treatment with urea and potassium sulfate (NK; P〈0.05). The results also show that the highest increases in SOC (P〈0.05) occurred in NPKM with a potential increase of 1.2 t C/(hm2.a). The increase in SOC was only 0.31, 0.30 and 0.12 t C/(hm2.a) for NPKS (9/10 N from NPK and 1/10 N from straw), NPK and NP, respectively; and the SOC in the NP, NK and CK treatments were approaching equilibrium and so did not rise or fall significantly over the 23-year experiment. A complete NPK plus manure fertilization program is recommended for this extremely arid region to maximize both yields and carbon sequestration.展开更多
Many of the important questions facing farming systems in the world today require long-term studies to provide meaningful information and answers. A long-term agronomic experiment (LTAE) should (1) have long-term obje...Many of the important questions facing farming systems in the world today require long-term studies to provide meaningful information and answers. A long-term agronomic experiment (LTAE) should (1) have long-term objectives; (2) study important soil processes or ecological processes; and (3) be related to the productivity and sustainability of systems. A well established LTAE can provide both insights into how the system operates and foresight into where the system goes. The prerequisites for setting up a LTAE are the secured land, continuous funding and dedicated scientists. A number of principles must be considered carefully when establishing a LTAE, (1) the site must be representative of large areas; (2) the treatments should be simple, but focusing on the big questions; (3) the plots should be large enough to allow subsequent modification of the experiment if this becomes necessary; (4) crop rotations should minimise, wherever possible, the risk of build-up of pests and diseases, and rotational phase should be considered in a rotational experiment; (5) a clearly defined experimental protocol should be developed to ensure data collected is scientifically valid and statistically analysable, but with flexibility to allow essential changes; (6) soil samples, possibly plant samples, should be achieved to provide better answer to the original questions when new, perhaps more accurate analytical techniques are developed, or answer new research questions that were not considered in the original design. The MASTER experiment in Australia was used as a case study to demonstrate how these principles are implemented in practice.展开更多
The efficient exploitation of geothermal energy through enhanced geothermal systems(EGS)has been a relevant topic for hot dry rock(HDR)geothermal resources.When cryogenic fluid is injected into a thermal reservoir,imp...The efficient exploitation of geothermal energy through enhanced geothermal systems(EGS)has been a relevant topic for hot dry rock(HDR)geothermal resources.When cryogenic fluid is injected into a thermal reservoir,improving heat exchange efficiency is key to achieving the optimal exploitation of HDR.In this paper,granite outcrops from Gonghe Basin were used as the testing sample.The natural fractures in the granite samples were relatively well developed.To simulate long-term injection and production from multi-wells in situ,physical ex-periments were performed in a newly-developed,in-house large-scale true triaxial experimental system.Geothermal extraction performance of an HDR was simulated for long-term injection and production operations.Simultaneously,the mode of one-injection and multiple-production wells was represented.In the paper,the ef-fects of the production-injection well spacing,the number of production wells and the injection rate on the production temperature and flow rate are discussed.The results show that,during long-term injection and pro-duction,there are two stages of production temperature variation,namely stabilization and attenuation.When the number of the production wells is increased,the heat extraction efficiency is accelerated.Moreover,competitive diversion of fluid among fractures occurred due to different conductivities.Furthermore,under different pro-duction modes,the production flow rate contributed differently to the heat extraction.Finally,the effect of the production-injection wells spacing on the heat exchange performance was analyzed;this is mainly reflected in the change of the effective heat exchange area between the rock and the injected fluid.The results emphasize the importance of designing an appropriate production mode and optimizing the injection-production parameters to ensure efficient HDR exploitation.展开更多
The systematic experiment regarding the general uniaxial compression test and the creep deformations of the typical limestones from the surrounding rock of the highway tunnels were made.The relationship between the ax...The systematic experiment regarding the general uniaxial compression test and the creep deformations of the typical limestones from the surrounding rock of the highway tunnels were made.The relationship between the axial stress and the delayed deformation steady value was obtained from the creep tests under low loading stresses.By the least square method,the parameters of Nishihara creep model were calculated from the creep curves.The results indicate that the strain change always lags behind the increase of stress,and the long-term strength of the limestone is about 80.6% of the stress at the volumetric strain reversal which is obtained from the conventional uniaxial compression test.展开更多
Long-term load and flexural failure experiments are carried out on two prestressed concrete(PC) simply supported box girders. In the long-term load experiment, girder-1(G1) is in an elastic state, while girder-2(G2) i...Long-term load and flexural failure experiments are carried out on two prestressed concrete(PC) simply supported box girders. In the long-term load experiment, girder-1(G1) is in an elastic state, while girder-2(G2) is in a cracking state. To investigate the influence of cracking on the flexural behaviors of PC simply supported box beams, the experiment results are analyzed from many aspects, such as load–deflection, load–strain, and failure mode. Experiment results show the following: 1) the shrinkage and creep of concrete have considerable influences on the long-term deflection and strain of the two girders; 2) in the flexural failure experiment, the cracks and ultimate loads of the two girders are close. The rigidity degeneration of G2 is significantly faster than that of G1, and thus G2 shows nonlinear characteristics earlier; 3) to prove the validity and rationality of the current code, the cracking load and ultimate load of the two girders are calculated according to the current code.展开更多
In the present study,a facility,i.e.,a mechanical deflection system (MDS),was established and applied to assess the long-term reliability of the solder joints in plastic ball grid array (BGA) assembly.It was found tha...In the present study,a facility,i.e.,a mechanical deflection system (MDS),was established and applied to assess the long-term reliability of the solder joints in plastic ball grid array (BGA) assembly.It was found that the MDS not only quickly assesses the long-term reliability of solder joints within days,but can also mimic similar failure mechanisms in accelerated thermal cycling (ATC) tests. Based on the MDS and ATC reliability experiments,the acceleration factors (AF) were obtained for different reliability testing conditions.Furthermore,by using the creep constitutive relation and fatigue life model developed in part I,a numerical approach was established for the purpose of virtual life prediction of solder joints. The simulation results were found to be in good agreement with the test results from the MDS.As a result,a new reliability assessment methodology was established as an alternative to ATC for the evaluation of long-term reliability of plastic BGA assembly.展开更多
Coordinated numerical ensemble experiments with six different state-of-the-art atmosphere models were used to evaluate and quantify the impact of global SST(from reanalysis data)on the early winter Arctic warming duri...Coordinated numerical ensemble experiments with six different state-of-the-art atmosphere models were used to evaluate and quantify the impact of global SST(from reanalysis data)on the early winter Arctic warming during 1982-2014.Two sets of experiments were designed:in the first set(EXP1),OISSTv2 daily sea-ice concentration and SST variations were used as the lower boundary forcing,while in the second set(EXP2)the SST data were replaced by the daily SST climatology.In the results,the multi-model ensemble mean of EXP1 showed a nearsurface(~850 hPa)warming trend of 0.4℃/10 yr,which was 80%of the warming trend in the reanalysis.The simulated warming trend was robust across the six models,with a magnitude of 0.36-0.50℃/10 yr.The global SST could explain most of the simulated warming trend in EXP1 in the mid and low troposphere over the Arctic,and accounted for 58%of the simulated near-surface warming.The results also suggest that the uppertropospheric warming(~200 hPa)over the Arctic in the reanalysis is likely not a forced signal;rather,it is caused by natural climate variability.The source regions that can potentially impact the early winter Arctic warming are explored and the limitations of the study are discussed.展开更多
Background: Traumatic brain injury (TBI) remains a cause of lifelong disability, death, and suicide worldwide. TBI-induced near-death experience (NDE) could increase suicide risks. Objective: We investigated TBI coupl...Background: Traumatic brain injury (TBI) remains a cause of lifelong disability, death, and suicide worldwide. TBI-induced near-death experience (NDE) could increase suicide risks. Objective: We investigated TBI coupled with NDE and posttraumatic stress disorder (PTSD) as a possible indicator of suicide. Methods: A 17-year-old male who sustained an acute severe TBI in a traffic collision, was comatose 14 days, had an NDE awakening from the coma, and, years after rehabilitation, suffered PTSD, clinical depression, and survived a suicide attempt. This personal experience of a TBI-induced NDE and lingering PTSD was acquired directly from the patient by interview. We discuss his case while considering relevant literature. Results: Longitudinal data from 1961 to 2021 generated from the PubMed interface revealed 4056 TBI patients committed suicide. NDE was only reported in one of those cases and, although not a suicide, in the personal experience. Neuropsychological assessment at long-term follow-ups revealed few TBI patients exhibited normal mental/physical functions compared to the general population. Unfavorable GOS scores were risk predictors for neuropsychological/physical impairments later in life, with outcomes of depression, PTSD, poor QOL, and/or suicide. Conclusions: For TBI-NDE survivors, including those with PTSD, long-term periodic neuropsychological follow-ups and psychosocial support may help decrease suicide risks.展开更多
Utilizing the European Centre for Medium-Range Weather Forecast(ECMWF)Reanalysis v5(ERA5),for the first time,we have confirmed close links among Sudden Stratospheric Warmings(SSWs)in the Northern Hemisphere(NH),the po...Utilizing the European Centre for Medium-Range Weather Forecast(ECMWF)Reanalysis v5(ERA5),for the first time,we have confirmed close links among Sudden Stratospheric Warmings(SSWs)in the Northern Hemisphere(NH),the polar vortices,and stratospheric Planetary Waves(PWs)by analyzing and comparing their trends.Interestingly,within overall increasing trends,the duration and strength of SSWs exhibit increasing and decreasing trends before and after the winter of 2002,respectively.To reveal possible physical mechanisms driving these trends,we analyzed the long-term trends of the winter(from December to February)polar vortices and of stratospheric PWs with zonal wave number 1.Notably,our results show that in all three time periods(the entire period of 41winters,1980 to 2020,and the two subperiods—1980-2002 and 2002-2020)enhancing SSWs were always accompanied by weakening winter polar vortices and strengthening polar PWs like Stationary Planetary Waves(SPWs)and 16-day waves,and vice versa.This is the first proof,based on ERA5 long-term trend data,that weakening polar vortices and enhancing stratospheric PWs(especially SPWs)could cause an increase in SSWs.展开更多
The change rules of the fertility of red soil paddy under the long-term different fertilization were investigated, and the reasonable fertilization mode to improve the fertility of red soil paddy was discussed. There ...The change rules of the fertility of red soil paddy under the long-term different fertilization were investigated, and the reasonable fertilization mode to improve the fertility of red soil paddy was discussed. There were eight treatments in the experiment, which were CK (no fertilizer), N1 (N of 60 kg/hm2), N2 (N of 120 kg/hm2), N1P1 (P2O5 of 30 kg/hm2), N2P1 and N2P2 (P2O5 of 60 kg/hm2), N2P2K1 (K2O of 45 kg/hm2) and N2P2K2 (K2O of 90 kg/hm2). All treatments were applied with composted cow dung as the base fertilizer, and each season 50% of the straws were returned to the field. The content of organic matter, nitrogen, phosphorous and potassium in red soil paddy was observed continuously for ten years and their correlation was also analyzed. Under cow manure and straw return to field, organic matter content of different treatments was positively correlated to year. After ten years, organic matter content of surface soil rose by 2.5 g/kg averagely with an annual increase of 0.25 g/kg. Total nitrogen content and organic matter content of different treatments presented similar variation trend. Total nitrogen content rose by 0.35 g/kg averagely with an annual increase of 0.035 g/kg. Among all the treatments, N2P2K1 and N2P2K2 showed the biggest increase, which went up by 0.052 and 0.48 g/kg, respectively. Phosphorous-free treatments (CK, N1, N2) had steady phosphorous content with irregular changes of different years. Total phosphorous content of phosphorous treatments increased year by year. Total phosphorous content of N1P1 and N2P1 rose by 0.008 g/kg every year. The increment range of total phosphorous content of N2P2, N2P2K1 and N2P2K2 was 0.012 -0.013 g/kg annually. Available phosphorous content varied vastly among different treatments. Available phosphorous content of organic fertilizer treatments basically remained stable with irregular changes of different years. Available phosphorous content of organic fertilizer with phosphate fertilizer treatments rose year by year. Available phosphorous content of N1P1 and N2P1 rose approximately by 0.8 mg/kg. Available phosphorous content of N2P2, N2P2K1 and N2P2K2 rose approximately by 1.4 -1.6 mg/kg annually. Potassium fertilizer amount greatly affected total potassium content. Total potassium content of no-potassium treatments (CK, N1, N2, N1P1, N2P1 and N2P2) remained the same. Total potassium content of N2P2K markedly increased year by year, which was 0.014 g/kg annually. Rapid available potassium content of no-potassium treatments (CK, N1, N2, N1P1, N2P1 and N2P2) showed a decreasing trend. With phosphate fertilizer, rapid available potassium content of N2P2K1 and N2P2K2 remained the same or increased year by year. The change trend of slow available potassium content and rapid available potassium content resembled. Rational allocation of organic fertilizer, nitrogenous fertilizer, phosphate fertilizer and potassium fertilizer can significantly improve soil fertility and economic benefits. Balanced fertilization is an effective measure for soil fertility improvement as it's shown that nutrients of surface soil accumulate annually.展开更多
基金National Program on Key Basic Research Project of China (973 Program) (2007CB411805 2010CB428505)National Natural Science Foundation of China (40830958)
文摘The impact of anomalous sea surface temperature (SST) warming in the Kuroshio Extension in the previous winter on the East Asian summer monsoon (EASM) was investigated by performing simulation tests using NCAR CAM3.The results show that anomalous SST warming in the Kuroshio Extension in winter causes the enhancement and northward movement of the EASM.The monsoon indexes for East Asian summer monsoon and land-sea thermal difference,which characterize the intensity of the EASM,show an obvious increase during the onset period of the EASM.Moreover,the land-sea thermal difference is more sensitive to warmer SST.Low-level southwesterly monsoon is clearly strengthened meanwhile westerly flows north (south) of the subtropical westerly jet axis are strengthened (weakened) in northern China,South China Sea,and the Western Pacific Ocean to the east of the Philippines.While there is an obvious decrease in precipitation over the Japanese archipelago and adjacent oceans and over the area from the south of the Yangtze River in eastern China to the Qinling Mountains in southern China,precipitation increases notably in northern China,the South China Sea,the East China Sea,the Yellow Sea,and the Western Pacific to the east of the Philippines.North China is the key area where the response of the EASM to the SST anomalous warming in the Kuroshio Extension is prominent.The surface air temperature shows a warming trend.The warming in the entire troposphere between 30oN and 50oN increases the land-sea thermal contrast,which plays an important role in the enhancement of the EASM.Atmospheric circulation and precipitation anomalies in China and its adjacent regions have a close relationship with the enhancement of the Western Pacific subtropical high and its northward extension.
基金This study was financially supported by the National Natural Science Foundation of China(41501219)the Applied Basic Research Project of Shanxi Province(2016021136)+2 种基金the National College Students'Innovative Entrepreneurial Training Plan Program of China(201910119007)the Research Project of Philosophy and Social Sciences in Colleges and Universities of Shanxi Province(2019W134)the Soft Science Research Project of Shanxi Province(2018041072-1).
文摘Ecosystems in high-altitude regions are more sensitive and respond more rapidly than other ecosystems to global climate warming.The Qinghai-Tibet Plateau(QTP)of China is an ecologically fragile zone that is sensitive to global climate warming.It is of great importance to study the changes in aboveground biomass and species diversity of alpine meadows on the QTP under predicted future climate warming.In this study,we selected an alpine meadow on the QTP as the study object and used infrared radiators as the warming device for a simulation experiment over eight years(2011-2018).We then analyzed the dynamic changes in aboveground biomass and species diversity of the alpine meadow at different time scales,including an early stage of warming(2011-2013)and a late stage of warming(2016-2018),in order to explore the response of alpine meadows to short-term(three years)and long-term warming(eight years).The results showed that the short-term warming increased air temperature by 0.31℃and decreased relative humidity by 2.54%,resulting in the air being warmer and drier.The long-term warming increased air temperature and relative humidity by 0.19℃and 1.47%,respectively,and the air tended to be warmer and wetter.The short-term warming increased soil temperature by 2.44℃and decreased soil moisture by 12.47%,whereas the long-term warming increased soil temperature by 1.76℃and decreased soil moisture by 9.90%.This caused the shallow soil layer to become warmer and drier under both short-term and long-term warming.Furthermore,the degree of soil drought was alleviated with increased warming duration.Under the long-term warming,the importance value and aboveground biomass of plants in different families changed.The importance values of grasses and sedges decreased by 47.56%and 3.67%,respectively,while the importance value of weeds increased by 1.37%.Aboveground biomass of grasses decreased by 36.55%,while those of sedges and weeds increased by 8.09%and 15.24%,respectively.The increase in temperature had a non-significant effect on species diversity.The species diversity indices increased at the early stage of warming and decreased at the late stage of warming,but none of them reached significant levels(P>0.05).Species diversity had no significant correlation with soil temperature and soil moisture under both short-term and long-term warming.Soil temperature and aboveground biomass were positively correlated in the control plots(P=0.014),but negatively correlated under the long-term warming(P=0.013).Therefore,eight years of warming aggravated drought in the shallow soil layer,which is beneficial for the growth of weeds but not for the growth of grasses.Warming changed the structure of alpine meadow communities and had a certain impact on the community species diversity.Our studies have great significance for the protection and effective utilization of alpine vegetation,as well as for the prevention of grassland degradation or desertification in high-altitude regions.
文摘The content of organic matter (OM), nitrogen (N), phosphorus (P), and potassium (K) in the three selected soils, including Calcaric Purpli-Orthic Primosols (purple sand-shale parent material), Dystric Turbi-Anthric Primosols (quaternary red clay parent material) and Typic Udi-Sandic Primosols (granite parent material) were studied under a long-term experiment by using crop straw and inorganic fertilizers at the Hunan Red Soil Experiment Station of Chinese Academy of Agricultural Sciences. The results showed that the contents of OM, N, P and K in the three selected soils increased after 23 years application of crop straw and inorganic fertilizers, but the contents increased much less when crop straw or inorganic fertilizers was applied alone. The nutrient contents in the three soils developed from granite changed more remarkably than those in the soil derived from quaternary red clay and purple sand-shale. It was also found that the contents of OM, N, and P increased slightly in the treatments without applying fertilizers or returning the crop straw to the root bed. Combined application of inorganic fertilizers and crop straw could remarkably increase the contents of OM, alkalihydrolyzable N and available K, the positive correlation between application of organic fertilizers and increase of OM in soil did not always happened, it provided evidence for the relation between appropriate C/N ratio and accumulation of OM in soil. The increase of nutrient content was influenced by the soil properties. By comparing the contents of nutrient in 0-20 cm depth in the three different soils, it was concluded that the most increases of OM, alkali-hydrolyzable N, and available P were observed in Typic Udi-Sandic Primosols with the average increase by 3.03, 27.38, and 21.73 mg kg^-1, respectively. The available K increased in Dystric Turbi-Anthric Primosols with the average increase by 25.82 mg kg^-1, while it decreased in Calcaric Purpli-Orthic Primosols and Typic Udi-Sandic Primosols. It was concluded that the application of inorganic fertilizer and crop straw was important to improve the soil fertility for all of three selected soils. The straw return to the field had played a significant role for enhancement of the soil quality in the study areas. The application of inorganic fertilizer combined with the straw return to the fields could remarkably improve the soil fertility.
基金funded by the National Basic Research Program of China(2014CB954200)the National Natural Science Foundation of China(41425007,41005001)the National Gray Desert Soil Fertility and Fertilizer Efficiency Monitoring Station of China
文摘A long-term fertilization experiment was set up in northern Xinjiang, China to evaluate the dynamics of crop production and soil organic carbon (SOC) from 1990 to 2012 with seven fertilization treatments. The seven treatments included an unfertilized control (CK) and six different combinations of phosphorus (P), potassium (K), nitrogen (N), straw (S) and animal manure (M). The balanced fertilization treatments had significantly (P〈0.05) higher average yields than the unbalanced ones. The treatment with 2/3 N from potassium sulfate (NPK) and 1/3 N from farmyard manure (NPKM) had a higher average yield than the other treatments. The average yields (over the 23 years) in the treatments of NPK, and urea, calcium superphosphate (NP) did not differ significantly (P〉0.05) but were higher than that in the treatment with urea and potassium sulfate (NK; P〈0.05). The results also show that the highest increases in SOC (P〈0.05) occurred in NPKM with a potential increase of 1.2 t C/(hm2.a). The increase in SOC was only 0.31, 0.30 and 0.12 t C/(hm2.a) for NPKS (9/10 N from NPK and 1/10 N from straw), NPK and NP, respectively; and the SOC in the NP, NK and CK treatments were approaching equilibrium and so did not rise or fall significantly over the 23-year experiment. A complete NPK plus manure fertilization program is recommended for this extremely arid region to maximize both yields and carbon sequestration.
基金supported by the CAS/SAFEA International Partnership Program for Creative Research Teams (CXTD-Z2005-2-4)
文摘Many of the important questions facing farming systems in the world today require long-term studies to provide meaningful information and answers. A long-term agronomic experiment (LTAE) should (1) have long-term objectives; (2) study important soil processes or ecological processes; and (3) be related to the productivity and sustainability of systems. A well established LTAE can provide both insights into how the system operates and foresight into where the system goes. The prerequisites for setting up a LTAE are the secured land, continuous funding and dedicated scientists. A number of principles must be considered carefully when establishing a LTAE, (1) the site must be representative of large areas; (2) the treatments should be simple, but focusing on the big questions; (3) the plots should be large enough to allow subsequent modification of the experiment if this becomes necessary; (4) crop rotations should minimise, wherever possible, the risk of build-up of pests and diseases, and rotational phase should be considered in a rotational experiment; (5) a clearly defined experimental protocol should be developed to ensure data collected is scientifically valid and statistically analysable, but with flexibility to allow essential changes; (6) soil samples, possibly plant samples, should be achieved to provide better answer to the original questions when new, perhaps more accurate analytical techniques are developed, or answer new research questions that were not considered in the original design. The MASTER experiment in Australia was used as a case study to demonstrate how these principles are implemented in practice.
文摘The efficient exploitation of geothermal energy through enhanced geothermal systems(EGS)has been a relevant topic for hot dry rock(HDR)geothermal resources.When cryogenic fluid is injected into a thermal reservoir,improving heat exchange efficiency is key to achieving the optimal exploitation of HDR.In this paper,granite outcrops from Gonghe Basin were used as the testing sample.The natural fractures in the granite samples were relatively well developed.To simulate long-term injection and production from multi-wells in situ,physical ex-periments were performed in a newly-developed,in-house large-scale true triaxial experimental system.Geothermal extraction performance of an HDR was simulated for long-term injection and production operations.Simultaneously,the mode of one-injection and multiple-production wells was represented.In the paper,the ef-fects of the production-injection well spacing,the number of production wells and the injection rate on the production temperature and flow rate are discussed.The results show that,during long-term injection and pro-duction,there are two stages of production temperature variation,namely stabilization and attenuation.When the number of the production wells is increased,the heat extraction efficiency is accelerated.Moreover,competitive diversion of fluid among fractures occurred due to different conductivities.Furthermore,under different pro-duction modes,the production flow rate contributed differently to the heat extraction.Finally,the effect of the production-injection wells spacing on the heat exchange performance was analyzed;this is mainly reflected in the change of the effective heat exchange area between the rock and the injected fluid.The results emphasize the importance of designing an appropriate production mode and optimizing the injection-production parameters to ensure efficient HDR exploitation.
基金Project(50774090) supported by the National Natural Science Foundation of China
文摘The systematic experiment regarding the general uniaxial compression test and the creep deformations of the typical limestones from the surrounding rock of the highway tunnels were made.The relationship between the axial stress and the delayed deformation steady value was obtained from the creep tests under low loading stresses.By the least square method,the parameters of Nishihara creep model were calculated from the creep curves.The results indicate that the strain change always lags behind the increase of stress,and the long-term strength of the limestone is about 80.6% of the stress at the volumetric strain reversal which is obtained from the conventional uniaxial compression test.
基金Project(51551801)supported by the National Natural Science Foundation of ChinaProject(14JJ4062)supported by Natural Science Foundation of Hunan Province,China
文摘Long-term load and flexural failure experiments are carried out on two prestressed concrete(PC) simply supported box girders. In the long-term load experiment, girder-1(G1) is in an elastic state, while girder-2(G2) is in a cracking state. To investigate the influence of cracking on the flexural behaviors of PC simply supported box beams, the experiment results are analyzed from many aspects, such as load–deflection, load–strain, and failure mode. Experiment results show the following: 1) the shrinkage and creep of concrete have considerable influences on the long-term deflection and strain of the two girders; 2) in the flexural failure experiment, the cracks and ultimate loads of the two girders are close. The rigidity degeneration of G2 is significantly faster than that of G1, and thus G2 shows nonlinear characteristics earlier; 3) to prove the validity and rationality of the current code, the cracking load and ultimate load of the two girders are calculated according to the current code.
基金The project supported by the National Natural Science Foundation of China (59705008)
文摘In the present study,a facility,i.e.,a mechanical deflection system (MDS),was established and applied to assess the long-term reliability of the solder joints in plastic ball grid array (BGA) assembly.It was found that the MDS not only quickly assesses the long-term reliability of solder joints within days,but can also mimic similar failure mechanisms in accelerated thermal cycling (ATC) tests. Based on the MDS and ATC reliability experiments,the acceleration factors (AF) were obtained for different reliability testing conditions.Furthermore,by using the creep constitutive relation and fatigue life model developed in part I,a numerical approach was established for the purpose of virtual life prediction of solder joints. The simulation results were found to be in good agreement with the test results from the MDS.As a result,a new reliability assessment methodology was established as an alternative to ATC for the evaluation of long-term reliability of plastic BGA assembly.
基金supported by the National Key R&D Program of China[grant number 2017YFE0111800]the National Natural Science Foundation of China[grant numbers 41790472 and 41661144005]partly supported by the EU H2020 Blue-Action project[grant number 727852]。
文摘Coordinated numerical ensemble experiments with six different state-of-the-art atmosphere models were used to evaluate and quantify the impact of global SST(from reanalysis data)on the early winter Arctic warming during 1982-2014.Two sets of experiments were designed:in the first set(EXP1),OISSTv2 daily sea-ice concentration and SST variations were used as the lower boundary forcing,while in the second set(EXP2)the SST data were replaced by the daily SST climatology.In the results,the multi-model ensemble mean of EXP1 showed a nearsurface(~850 hPa)warming trend of 0.4℃/10 yr,which was 80%of the warming trend in the reanalysis.The simulated warming trend was robust across the six models,with a magnitude of 0.36-0.50℃/10 yr.The global SST could explain most of the simulated warming trend in EXP1 in the mid and low troposphere over the Arctic,and accounted for 58%of the simulated near-surface warming.The results also suggest that the uppertropospheric warming(~200 hPa)over the Arctic in the reanalysis is likely not a forced signal;rather,it is caused by natural climate variability.The source regions that can potentially impact the early winter Arctic warming are explored and the limitations of the study are discussed.
文摘Background: Traumatic brain injury (TBI) remains a cause of lifelong disability, death, and suicide worldwide. TBI-induced near-death experience (NDE) could increase suicide risks. Objective: We investigated TBI coupled with NDE and posttraumatic stress disorder (PTSD) as a possible indicator of suicide. Methods: A 17-year-old male who sustained an acute severe TBI in a traffic collision, was comatose 14 days, had an NDE awakening from the coma, and, years after rehabilitation, suffered PTSD, clinical depression, and survived a suicide attempt. This personal experience of a TBI-induced NDE and lingering PTSD was acquired directly from the patient by interview. We discuss his case while considering relevant literature. Results: Longitudinal data from 1961 to 2021 generated from the PubMed interface revealed 4056 TBI patients committed suicide. NDE was only reported in one of those cases and, although not a suicide, in the personal experience. Neuropsychological assessment at long-term follow-ups revealed few TBI patients exhibited normal mental/physical functions compared to the general population. Unfavorable GOS scores were risk predictors for neuropsychological/physical impairments later in life, with outcomes of depression, PTSD, poor QOL, and/or suicide. Conclusions: For TBI-NDE survivors, including those with PTSD, long-term periodic neuropsychological follow-ups and psychosocial support may help decrease suicide risks.
基金supported by the National Key RandD Program of China(2022YFF0503703)the National Natural Science Foundation of China(through grant42127805)。
文摘Utilizing the European Centre for Medium-Range Weather Forecast(ECMWF)Reanalysis v5(ERA5),for the first time,we have confirmed close links among Sudden Stratospheric Warmings(SSWs)in the Northern Hemisphere(NH),the polar vortices,and stratospheric Planetary Waves(PWs)by analyzing and comparing their trends.Interestingly,within overall increasing trends,the duration and strength of SSWs exhibit increasing and decreasing trends before and after the winter of 2002,respectively.To reveal possible physical mechanisms driving these trends,we analyzed the long-term trends of the winter(from December to February)polar vortices and of stratospheric PWs with zonal wave number 1.Notably,our results show that in all three time periods(the entire period of 41winters,1980 to 2020,and the two subperiods—1980-2002 and 2002-2020)enhancing SSWs were always accompanied by weakening winter polar vortices and strengthening polar PWs like Stationary Planetary Waves(SPWs)and 16-day waves,and vice versa.This is the first proof,based on ERA5 long-term trend data,that weakening polar vortices and enhancing stratospheric PWs(especially SPWs)could cause an increase in SSWs.
基金Supported by the Natural Science Foundation of Guagnxi(2015GXNSFBA139098)the Special Fund for Science and Technology of the Ministry of Agriculture of China(201203030-07-02)+1 种基金the Fund Program of Guangxi Academy of Agricultural Sciences(2015YT30,2014JZ18,2013YF06)the Science and Technology Planning Project of Qingxiu District,Nanjing(2012N15)~~
文摘The change rules of the fertility of red soil paddy under the long-term different fertilization were investigated, and the reasonable fertilization mode to improve the fertility of red soil paddy was discussed. There were eight treatments in the experiment, which were CK (no fertilizer), N1 (N of 60 kg/hm2), N2 (N of 120 kg/hm2), N1P1 (P2O5 of 30 kg/hm2), N2P1 and N2P2 (P2O5 of 60 kg/hm2), N2P2K1 (K2O of 45 kg/hm2) and N2P2K2 (K2O of 90 kg/hm2). All treatments were applied with composted cow dung as the base fertilizer, and each season 50% of the straws were returned to the field. The content of organic matter, nitrogen, phosphorous and potassium in red soil paddy was observed continuously for ten years and their correlation was also analyzed. Under cow manure and straw return to field, organic matter content of different treatments was positively correlated to year. After ten years, organic matter content of surface soil rose by 2.5 g/kg averagely with an annual increase of 0.25 g/kg. Total nitrogen content and organic matter content of different treatments presented similar variation trend. Total nitrogen content rose by 0.35 g/kg averagely with an annual increase of 0.035 g/kg. Among all the treatments, N2P2K1 and N2P2K2 showed the biggest increase, which went up by 0.052 and 0.48 g/kg, respectively. Phosphorous-free treatments (CK, N1, N2) had steady phosphorous content with irregular changes of different years. Total phosphorous content of phosphorous treatments increased year by year. Total phosphorous content of N1P1 and N2P1 rose by 0.008 g/kg every year. The increment range of total phosphorous content of N2P2, N2P2K1 and N2P2K2 was 0.012 -0.013 g/kg annually. Available phosphorous content varied vastly among different treatments. Available phosphorous content of organic fertilizer treatments basically remained stable with irregular changes of different years. Available phosphorous content of organic fertilizer with phosphate fertilizer treatments rose year by year. Available phosphorous content of N1P1 and N2P1 rose approximately by 0.8 mg/kg. Available phosphorous content of N2P2, N2P2K1 and N2P2K2 rose approximately by 1.4 -1.6 mg/kg annually. Potassium fertilizer amount greatly affected total potassium content. Total potassium content of no-potassium treatments (CK, N1, N2, N1P1, N2P1 and N2P2) remained the same. Total potassium content of N2P2K markedly increased year by year, which was 0.014 g/kg annually. Rapid available potassium content of no-potassium treatments (CK, N1, N2, N1P1, N2P1 and N2P2) showed a decreasing trend. With phosphate fertilizer, rapid available potassium content of N2P2K1 and N2P2K2 remained the same or increased year by year. The change trend of slow available potassium content and rapid available potassium content resembled. Rational allocation of organic fertilizer, nitrogenous fertilizer, phosphate fertilizer and potassium fertilizer can significantly improve soil fertility and economic benefits. Balanced fertilization is an effective measure for soil fertility improvement as it's shown that nutrients of surface soil accumulate annually.