Clay,as the most common soil used for foundationfill,is widely used in various infrastructure projects.The phy-sical and mechanical properties of clay are influenced by the pore solution environment.This study uses a GD...Clay,as the most common soil used for foundationfill,is widely used in various infrastructure projects.The phy-sical and mechanical properties of clay are influenced by the pore solution environment.This study uses a GDS static/dynamic triaxial apparatus and nuclear magnetic resonance experiments to investigate the effects of cyclic loading on clay foundations.Moreover,the development of cumulative strain in clay is analyzed,and afitting model for cumulative plastic strain is introduced by considering factors such as NaCl solution concentration,con-solidation stress ratio,and cycle number.In particular,the effects of the NaCl solution concentration and con-solidation stress ratio on the pore distribution of the test samples before and after cyclic loading are examined,and the relationship between microscopic pore size and macroscopic cumulative strain is obtained accordingly.Our results show that as the consolidation stress ratio grows,an increasing number of large pores in the soil samples are transformed into small pores.As the NaCl solution concentration becomes higher,the number of small pores gradually decreases,while the number of large pores remains unchanged.Cyclic loading causes the disappearance of the large pores in the samples,and the average pore size before cyclic loading is posi-tively correlated with the axial cumulative strain after cyclic loading.The cumulative strain produced by the soil under cyclic loading is inversely proportional to the NaCl solution concentration and consolidation stress ratio.展开更多
Based on the data of national observation stations of CMISS system,artificial encrypted observation data of snow depth,ERA5 reanalysis data,the snowfall process in Ulanqab City from March 17 to 19,2022 was analyzed.It...Based on the data of national observation stations of CMISS system,artificial encrypted observation data of snow depth,ERA5 reanalysis data,the snowfall process in Ulanqab City from March 17 to 19,2022 was analyzed.It is found that the influencing system of the snowfall process was upper-air trough combined with ground inverted trough.Snowfall was not proportional to snow depth,and the relationship between the maximum snow depth and total snowfall varied in different value intervals.A large intensity of snowfall was a necessary condition for the formation of abundant accumulated snow when ground temperature was higher than 0℃.After the formation of accumulated snow,ground temperature changed less,and it was easy to produce accumulated snow as ground temperature was lower.The lower the temperature,the more conducive to the generation of accumulated snow.展开更多
Modeling for nitritation process was discussed and analyzed quantitatively for the factors that influence nitrite accumulation. The results indicated that pH, inorganic carbon source and Hydraulic Retention Time(HRT) ...Modeling for nitritation process was discussed and analyzed quantitatively for the factors that influence nitrite accumulation. The results indicated that pH, inorganic carbon source and Hydraulic Retention Time(HRT) as well as biomass concentration are the main factors that influenced the conversion ratio of ammonium to nitrite. A constant high pH can lead to a high nitritation rate and results in high conversion ratio on condition that free ammonia inhibition do not happen. In a CSTR system, without pH control, this conversion ratio can be monitored by pH variation in the reactor. The pH goes down far from the inlet level means a strongly nitrite accumulation. High concentration of alkalinity can promoted the conversion ratio by means of accelerating the nitritation rate through providing sufficient inorganic carbon source(carbon dioxide). When inorganic carbon source was depleted, the nitritation process stopped. HRT adjustment could be an efficient way to make the nitritation system run more flexible, which to some extent can meet the requirements of the fluctuant of inlet parameters such as ammonium concentration, pH, and temperature and so on. Biomass concentration is the key point, especially for a CSTR system in steady state, which was normally circumscribed by the characteristics of bacteria and may also affected by aeration mode and can be increased by prolonging the HRT on the condition of no nitrate accumulation when no recirculation available. The higher the biomass concentration is, the better the nitrite accumulation can be obtained.展开更多
Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sustainable production.In order to investigate the effect of various nitrogen to phosphorus ratios on c...Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sustainable production.In order to investigate the effect of various nitrogen to phosphorus ratios on cells growth,chlorophyll content and accumulation of lipids in Dunaliella tertiolecta,experiments were carried out in modified microalgal medium with inorganic nitrogen(nitrate-nitrogen) or organic nitrogen(urea-nitrogen) as the sole nitrogen source at initial N:P ratios ranging from 1:1 to 32:1.The favorable N:P of 16:1 in the nitrate-N or urea-N medium yielded the maximum cell density and specific growth rate.Decrease in chlorophyll content were observed at the N:P of 4:1 in both nitrate-N and urea-N cultures.It was also observed that the maximum lipids concentration was obtained at the N:P of 4:1 in both nitrate and urea nutrient medium.The lipid productivity and lipid content of cultures in the urea-N medium at the N:P of 4:1were markedly higher than those from cultures with other N:P ratios(p < 0.05).The results of this work illustrate the possibility that higher ratios of nitrogen to phosphorus have enhancing effect on cells growth of D.tertiolecta.Conversely,higher lipid accumulation is associated with a decrease in chlorophyll content under lower ratios of nitrogen to phosphorus.The results confirm the hypothesis of this study that a larger metabolic flux has been channeled to lipid accumulation in D.tertiolecta cells when the ratios of nitrogen to phosphorus drop below a critical level.展开更多
[Objective]The aim was to provide a theoretical basis for the rational configuration of ratio of row spacing to intrarow spacing(RS/IS)of double-cropping rice.[Methods]With early rice‘Ganxin 203’and‘Zhongjiazao 17...[Objective]The aim was to provide a theoretical basis for the rational configuration of ratio of row spacing to intrarow spacing(RS/IS)of double-cropping rice.[Methods]With early rice‘Ganxin 203’and‘Zhongjiazao 17’and late rice‘Ganxin 688’and‘Wufengyou T025’as materials,the effects of RS/IS on yield,nitrogen accumulation and utilization were studied in the same planting density of31.20×104hills/hm2.[Results]The results showed that yield of early rice was higher in RS/IS2.8(30.0 cm×10.7 cm)and RS/IS2.0(25.0 cm×12.8 cm)treatment,and lower in RS/IS5.0(40.0 cm×8.0 cm)and RS/IS1.3(20.0 cm×16.0 cm)treatment,while late rice were higher in RS/IS5.0and RS/IS2.0treatment,and lower in RS/IS2.8and RS/IS1.3treatment.Total nitrogen accumulation and apparent utilization ratio of nitrogen of early rice were higher in RS/IS2.0treatment and lower in RS/IS5.0treatment,while,for late rice were higher in RS/IS2.8treatment and lower in RS/IS5.0treatment.Nitrogen requirement for 100 kg grain production of early rice was higher in RS/IS1.3treatment and lower in RS/IS2.0treatment,while,for late rice were higher in RS/IS2.8treatment,lower in RS/IS5.0treatment.[Conclusion]In sum,4 varieties of early and late rice obtained higher yield in 25.0 cm×12.8 cm and lower yield in 20.0 cm×16.0 cm,and total nitrogen accumulation,nitrogen requirement for 100 kg grain production and apparent utilization ratio of nitrogen were all lower in 40.0 cm×8.0 cm.展开更多
文摘Clay,as the most common soil used for foundationfill,is widely used in various infrastructure projects.The phy-sical and mechanical properties of clay are influenced by the pore solution environment.This study uses a GDS static/dynamic triaxial apparatus and nuclear magnetic resonance experiments to investigate the effects of cyclic loading on clay foundations.Moreover,the development of cumulative strain in clay is analyzed,and afitting model for cumulative plastic strain is introduced by considering factors such as NaCl solution concentration,con-solidation stress ratio,and cycle number.In particular,the effects of the NaCl solution concentration and con-solidation stress ratio on the pore distribution of the test samples before and after cyclic loading are examined,and the relationship between microscopic pore size and macroscopic cumulative strain is obtained accordingly.Our results show that as the consolidation stress ratio grows,an increasing number of large pores in the soil samples are transformed into small pores.As the NaCl solution concentration becomes higher,the number of small pores gradually decreases,while the number of large pores remains unchanged.Cyclic loading causes the disappearance of the large pores in the samples,and the average pore size before cyclic loading is posi-tively correlated with the axial cumulative strain after cyclic loading.The cumulative strain produced by the soil under cyclic loading is inversely proportional to the NaCl solution concentration and consolidation stress ratio.
文摘Based on the data of national observation stations of CMISS system,artificial encrypted observation data of snow depth,ERA5 reanalysis data,the snowfall process in Ulanqab City from March 17 to 19,2022 was analyzed.It is found that the influencing system of the snowfall process was upper-air trough combined with ground inverted trough.Snowfall was not proportional to snow depth,and the relationship between the maximum snow depth and total snowfall varied in different value intervals.A large intensity of snowfall was a necessary condition for the formation of abundant accumulated snow when ground temperature was higher than 0℃.After the formation of accumulated snow,ground temperature changed less,and it was easy to produce accumulated snow as ground temperature was lower.The lower the temperature,the more conducive to the generation of accumulated snow.
文摘Modeling for nitritation process was discussed and analyzed quantitatively for the factors that influence nitrite accumulation. The results indicated that pH, inorganic carbon source and Hydraulic Retention Time(HRT) as well as biomass concentration are the main factors that influenced the conversion ratio of ammonium to nitrite. A constant high pH can lead to a high nitritation rate and results in high conversion ratio on condition that free ammonia inhibition do not happen. In a CSTR system, without pH control, this conversion ratio can be monitored by pH variation in the reactor. The pH goes down far from the inlet level means a strongly nitrite accumulation. High concentration of alkalinity can promoted the conversion ratio by means of accelerating the nitritation rate through providing sufficient inorganic carbon source(carbon dioxide). When inorganic carbon source was depleted, the nitritation process stopped. HRT adjustment could be an efficient way to make the nitritation system run more flexible, which to some extent can meet the requirements of the fluctuant of inlet parameters such as ammonium concentration, pH, and temperature and so on. Biomass concentration is the key point, especially for a CSTR system in steady state, which was normally circumscribed by the characteristics of bacteria and may also affected by aeration mode and can be increased by prolonging the HRT on the condition of no nitrate accumulation when no recirculation available. The higher the biomass concentration is, the better the nitrite accumulation can be obtained.
基金partially supported by Tianjin Marine Revitalization Plan of Science and Technology (No.KJXH2013-16) from Tianjin Oceanic Administration,China
文摘Microalgal lipids are regarded as main future feedstock of biofuels for its higher efficiency of accumulation and sustainable production.In order to investigate the effect of various nitrogen to phosphorus ratios on cells growth,chlorophyll content and accumulation of lipids in Dunaliella tertiolecta,experiments were carried out in modified microalgal medium with inorganic nitrogen(nitrate-nitrogen) or organic nitrogen(urea-nitrogen) as the sole nitrogen source at initial N:P ratios ranging from 1:1 to 32:1.The favorable N:P of 16:1 in the nitrate-N or urea-N medium yielded the maximum cell density and specific growth rate.Decrease in chlorophyll content were observed at the N:P of 4:1 in both nitrate-N and urea-N cultures.It was also observed that the maximum lipids concentration was obtained at the N:P of 4:1 in both nitrate and urea nutrient medium.The lipid productivity and lipid content of cultures in the urea-N medium at the N:P of 4:1were markedly higher than those from cultures with other N:P ratios(p < 0.05).The results of this work illustrate the possibility that higher ratios of nitrogen to phosphorus have enhancing effect on cells growth of D.tertiolecta.Conversely,higher lipid accumulation is associated with a decrease in chlorophyll content under lower ratios of nitrogen to phosphorus.The results confirm the hypothesis of this study that a larger metabolic flux has been channeled to lipid accumulation in D.tertiolecta cells when the ratios of nitrogen to phosphorus drop below a critical level.
基金Supported by the Project of "Demonstration and Integration of Agricultural Non-point Source Pollution Prevention and Control Technology in Rice Production Areas of Southern Plain of China"Belonging to National Science and Technology Program for"Twelfth Five-Year"Plan(2012BAD15B03)Youth Innovation Funds of Jiangxi Academy of Agricultural Sciences "Effects of Row-Spacing on Yield of Different Double Cropping Rice Varieties and Its Mechanism"(2010-CQN004)
文摘[Objective]The aim was to provide a theoretical basis for the rational configuration of ratio of row spacing to intrarow spacing(RS/IS)of double-cropping rice.[Methods]With early rice‘Ganxin 203’and‘Zhongjiazao 17’and late rice‘Ganxin 688’and‘Wufengyou T025’as materials,the effects of RS/IS on yield,nitrogen accumulation and utilization were studied in the same planting density of31.20×104hills/hm2.[Results]The results showed that yield of early rice was higher in RS/IS2.8(30.0 cm×10.7 cm)and RS/IS2.0(25.0 cm×12.8 cm)treatment,and lower in RS/IS5.0(40.0 cm×8.0 cm)and RS/IS1.3(20.0 cm×16.0 cm)treatment,while late rice were higher in RS/IS5.0and RS/IS2.0treatment,and lower in RS/IS2.8and RS/IS1.3treatment.Total nitrogen accumulation and apparent utilization ratio of nitrogen of early rice were higher in RS/IS2.0treatment and lower in RS/IS5.0treatment,while,for late rice were higher in RS/IS2.8treatment and lower in RS/IS5.0treatment.Nitrogen requirement for 100 kg grain production of early rice was higher in RS/IS1.3treatment and lower in RS/IS2.0treatment,while,for late rice were higher in RS/IS2.8treatment,lower in RS/IS5.0treatment.[Conclusion]In sum,4 varieties of early and late rice obtained higher yield in 25.0 cm×12.8 cm and lower yield in 20.0 cm×16.0 cm,and total nitrogen accumulation,nitrogen requirement for 100 kg grain production and apparent utilization ratio of nitrogen were all lower in 40.0 cm×8.0 cm.
