The aim of this paper is to investigate the effect of nitrite intercalated Mg-Al layered double hydroxides(Mg-Al LDH-NO_(2))on mortar durability under the coexisting environment of Cl−and SO_(4)^(2-).Cl−and SO_(4)^(2-...The aim of this paper is to investigate the effect of nitrite intercalated Mg-Al layered double hydroxides(Mg-Al LDH-NO_(2))on mortar durability under the coexisting environment of Cl−and SO_(4)^(2-).Cl−and SO_(4)^(2-) binding properties of Mg-Al LDH-NO_(2) in simulated concrete pore solutions,Cl−and SO_(4)^(2-) diffusion properties of mortars with Mg-Al LDHNO 2 were examined.The steel corrosion and resistance of mortar against SO_(4)^(2-) attack were also evaluated.The results indicate that Mg-Al LDH-NO_(2) can effectively adsorb the Cl−and SO_(4)^(2-) in simulated concrete pore solution,and inhibit the diffusion of Cl−and SO_(4)^(2-) into cement mortars.The presence of SO_(4)^(2-) can greatly affect the uptake amount of Cl−,and there is a coupled effect of Cl−and SO_(4)^(2-) on their penetration into mortar specimens.In addition,Mg-Al LDH-NO_(2) can greatly upgrade the resistance of mortars against SO_(4)^(2-) attack and well prevent the steel from corrosion.However,Cl−will aggravate the SO_(4)^(2-) attack and SO_(4)^(2-) can initially decrease and then increase the steel corrosion.展开更多
In a time of the global market economy, if one wants to live harmoniously together with nature or living environment, he should not think with a theoretical mode of dualist contradiction but that of harmony and coexis...In a time of the global market economy, if one wants to live harmoniously together with nature or living environment, he should not think with a theoretical mode of dualist contradiction but that of harmony and coexistence such as ＂wholeness of man and nature＂. To illustrate this point, this paper thinks The Woman Warrior and Ballad of Eternal Sorrow are two significant texts： Ballad of Eternal Sorrow tells an ordinary, self-respecting, and life-respecting story of WANG Qi-yao and the girls like her as well as the city Shanghai. They blend into one harmonious whole： The city is like the girls and the girls match the city. Likewise, The Woman Warrior highlights the significance of naturc on the girl narrator＇s epiphany and healthy growth. The narrator comes to understand that paradoxes are the basic existent condition of human beings and so what she needs to do is to be magnanimous and balanceable in accepting these paradoxes.展开更多
To understand the impact of environmental heterogeneity and mutualistic interaction of species, we consider a mutualistic model with cross-diffusion in a heterogeneous environ- ment. Semi-coexistence states have been ...To understand the impact of environmental heterogeneity and mutualistic interaction of species, we consider a mutualistic model with cross-diffusion in a heterogeneous environ- ment. Semi-coexistence states have been studied by using the corresponding eigenvalue problems, and sufficient conditions for the existence and non-existence of coexistence states are given. Our results show that the model possesses at least one coexistence solution if the intrinsic populations growth rates are big or free-diffusion and cross-diffusion coefficients are weak. Otherwise, the model have no coexistence solution. The true solutions are obtained by utilizing the monotone iterative schemes. In order to illustrate our analytical results, some numerical simulations are given.展开更多
We analyzed plasma perturbations occurring in the coexisting environment of powerful VLF transmitter emission, intense lightning strokes and strong seismic activity during pregnant period. The results suggest that ano...We analyzed plasma perturbations occurring in the coexisting environment of powerful VLF transmitter emission, intense lightning strokes and strong seismic activity during pregnant period. The results suggest that anomalous electron bursts with energy dispersion in the range of ~100–350 keV, forming the "wisp" signature, are due to cyclotron resonance of electrons with monochromatic waves from the powerful NWC VLF transmitters during nighttime. The intense broad band VLF emissions (up-going 0+ whistlers) are observed while the DEMETER satellite goes through the region of intense thunderstorm activities at mid-latitudes. However, the effects of intense lightning activity and pregnant earthquake have little impact on this kind of stable energy-dispersed electron structures, despite the fact that they are presumably two primary reasons for the particle precipitation in the ionosphere. The case studied here provides us a valuable opportunity to address the various sources triggering the anomalous plasma perturbations in the ionosphere.展开更多
Aims Diversity in communities is determined by species’ability to coexist with each other and to overcome environmental stress that may act as an environmental filter.Niche differentiation(ND)results in stronger intr...Aims Diversity in communities is determined by species’ability to coexist with each other and to overcome environmental stress that may act as an environmental filter.Niche differentiation(ND)results in stronger intra-than interspecific competition and promotes coexistence.Because stress affects interactions,the strength of ND may change along stress gradients.A greater diversity of plant growth forms has been observed in stressful habitats,such as deserts and alpine regions,suggesting greater ND when stress is strong.We tested the hypothesis that niche differences and environmental filters become stronger with stress.Methods In a semiarid grassland in southern Mexico,we sowed six annual species in the field along a hydric stress gradient.Plants were grown alone(without interactions),with conspecific neighbors(intraspecific interactions)or with heterospecific neighbors(interspecific interactions).We analyzed how the ratio of intra-to interspecific competition changed along the gradient to assess how water availability determines the strength of ND.We also determined if hydric stress represented an environmental filter.Important Findings We observed stronger intra-than interspecific competition,especially where hydric stress was greater.Thus,we found ND in at least some portion of the gradient for all but one species.Some species were hindered by stress,but others were favored by it perhaps because it eliminates soil pathogens.Although strong ND was slightly more frequent with stress,our species sample was small and there were exceptions to the general pattern,so further research is needed to establish if this is a widespread phenomenon in nature.展开更多
基金Project(51478164)supported by the National Natural Science Foundation of ChinaProject(BK20181306)supported by Natural Science Foundation of Jiangsu Province,China。
文摘The aim of this paper is to investigate the effect of nitrite intercalated Mg-Al layered double hydroxides(Mg-Al LDH-NO_(2))on mortar durability under the coexisting environment of Cl−and SO_(4)^(2-).Cl−and SO_(4)^(2-) binding properties of Mg-Al LDH-NO_(2) in simulated concrete pore solutions,Cl−and SO_(4)^(2-) diffusion properties of mortars with Mg-Al LDHNO 2 were examined.The steel corrosion and resistance of mortar against SO_(4)^(2-) attack were also evaluated.The results indicate that Mg-Al LDH-NO_(2) can effectively adsorb the Cl−and SO_(4)^(2-) in simulated concrete pore solution,and inhibit the diffusion of Cl−and SO_(4)^(2-) into cement mortars.The presence of SO_(4)^(2-) can greatly affect the uptake amount of Cl−,and there is a coupled effect of Cl−and SO_(4)^(2-) on their penetration into mortar specimens.In addition,Mg-Al LDH-NO_(2) can greatly upgrade the resistance of mortars against SO_(4)^(2-) attack and well prevent the steel from corrosion.However,Cl−will aggravate the SO_(4)^(2-) attack and SO_(4)^(2-) can initially decrease and then increase the steel corrosion.
文摘In a time of the global market economy, if one wants to live harmoniously together with nature or living environment, he should not think with a theoretical mode of dualist contradiction but that of harmony and coexistence such as ＂wholeness of man and nature＂. To illustrate this point, this paper thinks The Woman Warrior and Ballad of Eternal Sorrow are two significant texts： Ballad of Eternal Sorrow tells an ordinary, self-respecting, and life-respecting story of WANG Qi-yao and the girls like her as well as the city Shanghai. They blend into one harmonious whole： The city is like the girls and the girls match the city. Likewise, The Woman Warrior highlights the significance of naturc on the girl narrator＇s epiphany and healthy growth. The narrator comes to understand that paradoxes are the basic existent condition of human beings and so what she needs to do is to be magnanimous and balanceable in accepting these paradoxes.
基金This work was partially supported by the National Natural Science Foundation of China （11771381） and Project funded by China Postdoctoral Science Foundation.
文摘To understand the impact of environmental heterogeneity and mutualistic interaction of species, we consider a mutualistic model with cross-diffusion in a heterogeneous environ- ment. Semi-coexistence states have been studied by using the corresponding eigenvalue problems, and sufficient conditions for the existence and non-existence of coexistence states are given. Our results show that the model possesses at least one coexistence solution if the intrinsic populations growth rates are big or free-diffusion and cross-diffusion coefficients are weak. Otherwise, the model have no coexistence solution. The true solutions are obtained by utilizing the monotone iterative schemes. In order to illustrate our analytical results, some numerical simulations are given.
基金supported by the National Natural Science Foundation of China (Grant No. 41431071)
文摘We analyzed plasma perturbations occurring in the coexisting environment of powerful VLF transmitter emission, intense lightning strokes and strong seismic activity during pregnant period. The results suggest that anomalous electron bursts with energy dispersion in the range of ~100–350 keV, forming the "wisp" signature, are due to cyclotron resonance of electrons with monochromatic waves from the powerful NWC VLF transmitters during nighttime. The intense broad band VLF emissions (up-going 0+ whistlers) are observed while the DEMETER satellite goes through the region of intense thunderstorm activities at mid-latitudes. However, the effects of intense lightning activity and pregnant earthquake have little impact on this kind of stable energy-dispersed electron structures, despite the fact that they are presumably two primary reasons for the particle precipitation in the ionosphere. The case studied here provides us a valuable opportunity to address the various sources triggering the anomalous plasma perturbations in the ionosphere.
基金supported by the Dirección General de Asuntos del Personal Académico,Universidad Nacional Autónoma de México(IN212618).
文摘Aims Diversity in communities is determined by species’ability to coexist with each other and to overcome environmental stress that may act as an environmental filter.Niche differentiation(ND)results in stronger intra-than interspecific competition and promotes coexistence.Because stress affects interactions,the strength of ND may change along stress gradients.A greater diversity of plant growth forms has been observed in stressful habitats,such as deserts and alpine regions,suggesting greater ND when stress is strong.We tested the hypothesis that niche differences and environmental filters become stronger with stress.Methods In a semiarid grassland in southern Mexico,we sowed six annual species in the field along a hydric stress gradient.Plants were grown alone(without interactions),with conspecific neighbors(intraspecific interactions)or with heterospecific neighbors(interspecific interactions).We analyzed how the ratio of intra-to interspecific competition changed along the gradient to assess how water availability determines the strength of ND.We also determined if hydric stress represented an environmental filter.Important Findings We observed stronger intra-than interspecific competition,especially where hydric stress was greater.Thus,we found ND in at least some portion of the gradient for all but one species.Some species were hindered by stress,but others were favored by it perhaps because it eliminates soil pathogens.Although strong ND was slightly more frequent with stress,our species sample was small and there were exceptions to the general pattern,so further research is needed to establish if this is a widespread phenomenon in nature.
