Desert plants take on unique physiologically adaptive mechanisms in response to an adverse environment. In this study, we determined the concentrations of leaf nitrogen(N), phosphorus(P), and calcium(Ca) fraction for ...Desert plants take on unique physiologically adaptive mechanisms in response to an adverse environment. In this study, we determined the concentrations of leaf nitrogen(N), phosphorus(P), and calcium(Ca) fraction for dominant species of Artemisia ordosica, A. frigida, Calligonum mongolicum, and Oxytropis aciphylla in the Alxa Desert and discussed seasonal changes of their leaf N:P ratio and Ca fraction. The results showed that, from May to September, the N:P ratios of A. ordosica and C. mongolicum gradually and significantly increased, while those of A. frigida, and O. aciphylla had an increase trend that was not significant; the physiologically active Ca of A. ordosica and A. frigida increased significantly,while that of C. mongolicum and O. aciphylla decreased significantly. The physiologically inert calcium of C. mongolicum increased extremely significantly, while that of others was not significant. There was a significantly positive correlation between the N:P ratio and physiologically active Ca for A. ordosica, and the N:P ratio was significantly and negatively correlated with physiologically active Ca for O. aciphylla. These findings revealed that the physiological regulation mechanism was different for the plants either in earlier stage or later stage of plant-community succession.展开更多
Based on the theory of complex adaptive system(CAS),the optimal allocation model of water resources in sewage irrigation areas was established,which provided new ideas and application value for the rational utilizatio...Based on the theory of complex adaptive system(CAS),the optimal allocation model of water resources in sewage irrigation areas was established,which provided new ideas and application value for the rational utilization of agricultural production and waste water resources.The results demonstrated that the difference of crop energy capture mainly depended on the development stage.Waste water with a certain concentration was able to promote crop growth,while excessive concentration inhibited crop growth.The correlation between water absorption rate and leaf area index was close(R=0.9498,p<0.01).The amount of bad seeds increased at a speed of 34.7·d^-1,when system irrigated randomly in the seedling stage,while it tended to remain stable at a speed of 0.3·d^-1 after plants entering the mature stage which impacted the total yields of crops.展开更多
The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kineti...The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.展开更多
Calmodulin （CAM） is involved in the regulation of a variety of cellular signaling pathways. To accomplish its physiological functions, CaM binds with Ca2＋ at its EF-hand Ca2＋ binding sites which induce the conform...Calmodulin （CAM） is involved in the regulation of a variety of cellular signaling pathways. To accomplish its physiological functions, CaM binds with Ca2＋ at its EF-hand Ca2＋ binding sites which induce the conformational switching of CaM. However, the molecular mechanism by which Ca2＋ binds with CaM and induces conformational switching is still obscure. Here we combine molecular dynamics with targeted molecular dynamics simulation and achieve the state-transition pathway of CaM. Our data show that Ca2＋ binding speeds up the conformational transition of CaM by weakening the interactions which stabilize the closed state. It spends about 6.5 ns and 5.25 ns for transition from closed state to open state for apo and holo CaM, respectively. Regarding the contribution of two EF-hands, our data indicate that the first EF-hand triggers the conformational transition and is followed by the second one. We determine that there are two interaction networks which contribute to stabilize the closed and open states, respectively.展开更多
In consideration of the mechanism for shear-stress-induced Ca^2＋ influx via ATP（adenosine triphosphate）-gated ion channel P2X4 in vascular endothelial cells, a modified model is proposed to describe the shear-stres...In consideration of the mechanism for shear-stress-induced Ca^2＋ influx via ATP（adenosine triphosphate）-gated ion channel P2X4 in vascular endothelial cells, a modified model is proposed to describe the shear-stress-induced Ca^2＋ influx. It is affected both by the Ca^2＋ gradient across the cell membrane and extracellular ATP concentration on the cell surface. Meanwhile, a new static ATP release model is constructed by using published experimental data. Combining the modified intracellular calcium dynamics model with the new ATP release model, we establish a nonlinear Ca^2＋ dynamic system in vascular endothelial cells. The ATP-mediated calcium response in vascular endothelial cells subjected to shear stresses is analyzed by solving the governing equations of the integrated dynamic system. Numerical results show that the shear-stress-induced calcium response predicted by the proposed model is more consistent with the experimental observations than that predicted by existing models.展开更多
The mechanical properties and texture of AM60（Mg-6.0Al-0.3Mn,mass fraction %） and ZXM200（Mg-1.6Zn-0.5Ca-0.2Mn） Mg alloys subjected to multi-pass hot rolling were investigated.The finer recrystallized grains usuall...The mechanical properties and texture of AM60（Mg-6.0Al-0.3Mn,mass fraction %） and ZXM200（Mg-1.6Zn-0.5Ca-0.2Mn） Mg alloys subjected to multi-pass hot rolling were investigated.The finer recrystallized grains usually exhibit particular preferred orientations and then alter the total texture feature of rolled sheets.Ca solid solution into Mg matrix serves to the formation of texture component with c-axis rotated away from normal direction towards transverse direction and then weakens the overall texture intensity,resulting in a similar anisotropic characteristic to RE-containing Mg alloys.展开更多
A molecular dynamics simulation study was performed to investigate the formation and evolution mechanisms of nano-clusters during the rapid solidification of liquid CaToMg30 alloy. The cluster-type index method （CTIM...A molecular dynamics simulation study was performed to investigate the formation and evolution mechanisms of nano-clusters during the rapid solidification of liquid CaToMg30 alloy. The cluster-type index method （CTIM） was adopted to describe microstructure evolutions of nano-clusters during solidification. Results indicate that amorphous structure is mainly formed with three bond-types of 1551, 1541 and 1431 at the cooling rate of 5~1011 K/S, and glass transition temperature Tg is about 530 K; the icosahedron cluster of （12 0 12 0） plays a key role in formation of amorphous structure, and smaller Mg atoms are much more probable to be central atoms of icosahedron clusters; and nano-clusters are mainly formed by combining medium-size clusters. Interestingly, it was also found that formation and evolution processes of the nano-cluster display a three-stage feature which is analogous to crystallization process of amorphous alloy.展开更多
基金supported by the National Key R&D Program of China (2016YFC0500706)
文摘Desert plants take on unique physiologically adaptive mechanisms in response to an adverse environment. In this study, we determined the concentrations of leaf nitrogen(N), phosphorus(P), and calcium(Ca) fraction for dominant species of Artemisia ordosica, A. frigida, Calligonum mongolicum, and Oxytropis aciphylla in the Alxa Desert and discussed seasonal changes of their leaf N:P ratio and Ca fraction. The results showed that, from May to September, the N:P ratios of A. ordosica and C. mongolicum gradually and significantly increased, while those of A. frigida, and O. aciphylla had an increase trend that was not significant; the physiologically active Ca of A. ordosica and A. frigida increased significantly,while that of C. mongolicum and O. aciphylla decreased significantly. The physiologically inert calcium of C. mongolicum increased extremely significantly, while that of others was not significant. There was a significantly positive correlation between the N:P ratio and physiologically active Ca for A. ordosica, and the N:P ratio was significantly and negatively correlated with physiologically active Ca for O. aciphylla. These findings revealed that the physiological regulation mechanism was different for the plants either in earlier stage or later stage of plant-community succession.
基金Supported by the Science and Technology Research Project of the Ministry of Education(14YJCZH017)the Major State Basic Research Development Program of China(973 Program)(2017YFC0404503)+1 种基金Key Cultivation Project of Lingnan Normal University in 2019(LZ1903)Lingnan Normal University Special Talent Program(ZL2007)
文摘Based on the theory of complex adaptive system(CAS),the optimal allocation model of water resources in sewage irrigation areas was established,which provided new ideas and application value for the rational utilization of agricultural production and waste water resources.The results demonstrated that the difference of crop energy capture mainly depended on the development stage.Waste water with a certain concentration was able to promote crop growth,while excessive concentration inhibited crop growth.The correlation between water absorption rate and leaf area index was close(R=0.9498,p<0.01).The amount of bad seeds increased at a speed of 34.7·d^-1,when system irrigated randomly in the seedling stage,while it tended to remain stable at a speed of 0.3·d^-1 after plants entering the mature stage which impacted the total yields of crops.
基金Supported by a grant from Tianji Coal Chemical Group Co.Ltd.(Project no.2012-1978)Shenzhen Batian Ecological Engineering Co.,Ltd.(Project no.2013-0909).
文摘The separation of Ca2+and Mg2+ions from phosphoric acid-nitric acid aqueous solution is very significant for the neutralization process of nitrophosphate fertilizer.This paper studied the adsorption equilibrium,kinetics,and dynamic separation of Ca2+and Mg2+ions by strong acid cation resin,and the effects of phosphoric acid and nitric acid on the adsorption process were investigated.The results reveal that the adsorption process of Ca2+and Mg2+ions in pure water on resin is in good agreement with the Langmuir isotherm model and their maximal adsorption capacities are 1.86 mmol·g-1 and 1.83 mmol·g-1,respectively.The adsorption kinetics of Ca2+and Mg2+ions on resin fits better with the pseudo-first-order model,and the adsorption equilibrium in pure water is reached within 10 min contact time,while at the present of phosphoric acid,the adsorption rate of Ca2+and Mg2+ions on resin will go down.The dynamic separation experiments demonstrate that the designed column adsorption is able to undertake the separation of metal ions from the mix acids aqueous solution,but the dynamic operation should control the flow rate of mix acid solution.Besides nitric acid solution was proved to be effective to completely regenerate the spent resin and achieve the recyclable operation of separation process.
基金Supported by the Natural Science Fund for Distinguished Young Scholars of Hebei Province under Grant Nos C2015202340 and C2013202244the Fund for Outstanding Talents of Hebei Province under Grant No C201400305+3 种基金the National Natural Science Fund of China under Grant Nos 11247010,11175055,11475053,11347017,31600594,31400711 and 11647121the Fund for the Science and Technology Program of Higher Education Institutions of Hebei Province under Grant No QN2016113the Scientific Innovation Grant for Excellent Young Scientists of Hebei University of Technology under Grant No 2015010the Natural Science Foundation of Hebei Province under Grant No C2017202208
文摘Calmodulin （CAM） is involved in the regulation of a variety of cellular signaling pathways. To accomplish its physiological functions, CaM binds with Ca2＋ at its EF-hand Ca2＋ binding sites which induce the conformational switching of CaM. However, the molecular mechanism by which Ca2＋ binds with CaM and induces conformational switching is still obscure. Here we combine molecular dynamics with targeted molecular dynamics simulation and achieve the state-transition pathway of CaM. Our data show that Ca2＋ binding speeds up the conformational transition of CaM by weakening the interactions which stabilize the closed state. It spends about 6.5 ns and 5.25 ns for transition from closed state to open state for apo and holo CaM, respectively. Regarding the contribution of two EF-hands, our data indicate that the first EF-hand triggers the conformational transition and is followed by the second one. We determine that there are two interaction networks which contribute to stabilize the closed and open states, respectively.
基金the National Natural Science Foundation of China(No.10472027) the NUS Academic Research Fund(No.R-263-000-483-112)
文摘In consideration of the mechanism for shear-stress-induced Ca^2＋ influx via ATP（adenosine triphosphate）-gated ion channel P2X4 in vascular endothelial cells, a modified model is proposed to describe the shear-stress-induced Ca^2＋ influx. It is affected both by the Ca^2＋ gradient across the cell membrane and extracellular ATP concentration on the cell surface. Meanwhile, a new static ATP release model is constructed by using published experimental data. Combining the modified intracellular calcium dynamics model with the new ATP release model, we establish a nonlinear Ca^2＋ dynamic system in vascular endothelial cells. The ATP-mediated calcium response in vascular endothelial cells subjected to shear stresses is analyzed by solving the governing equations of the integrated dynamic system. Numerical results show that the shear-stress-induced calcium response predicted by the proposed model is more consistent with the experimental observations than that predicted by existing models.
基金Project(51204003)supported by the National Natural Science Foundation of ChinaProject(KJ2011A051)supported by the Scientific Research Foundation of Education Department of Anhui Province,China
文摘The mechanical properties and texture of AM60（Mg-6.0Al-0.3Mn,mass fraction %） and ZXM200（Mg-1.6Zn-0.5Ca-0.2Mn） Mg alloys subjected to multi-pass hot rolling were investigated.The finer recrystallized grains usually exhibit particular preferred orientations and then alter the total texture feature of rolled sheets.Ca solid solution into Mg matrix serves to the formation of texture component with c-axis rotated away from normal direction towards transverse direction and then weakens the overall texture intensity,resulting in a similar anisotropic characteristic to RE-containing Mg alloys.
基金Project(50831003) supported by the National Natural Science Foundation of ChinaProject(20114BAB215026) supported by Jiangxi Provincial Natural Science Foundation,ChinaProject(ZD201002) supported by Fund for Basic Scientific Research of Gannan Medical University,China
文摘A molecular dynamics simulation study was performed to investigate the formation and evolution mechanisms of nano-clusters during the rapid solidification of liquid CaToMg30 alloy. The cluster-type index method （CTIM） was adopted to describe microstructure evolutions of nano-clusters during solidification. Results indicate that amorphous structure is mainly formed with three bond-types of 1551, 1541 and 1431 at the cooling rate of 5~1011 K/S, and glass transition temperature Tg is about 530 K; the icosahedron cluster of （12 0 12 0） plays a key role in formation of amorphous structure, and smaller Mg atoms are much more probable to be central atoms of icosahedron clusters; and nano-clusters are mainly formed by combining medium-size clusters. Interestingly, it was also found that formation and evolution processes of the nano-cluster display a three-stage feature which is analogous to crystallization process of amorphous alloy.
