Exploring anode materials with high energy and power density is one of the critical milestones in developing sodium-ion batteries/capacitors(SIBs/SICs).Here,the Mo and W-based bimetallic organic framework(Mo-W-MOF)wit...Exploring anode materials with high energy and power density is one of the critical milestones in developing sodium-ion batteries/capacitors(SIBs/SICs).Here,the Mo and W-based bimetallic organic framework(Mo-W-MOF)with core-shell structure is first formed by a facile strategy,followed by a selenization and carbonization strategy to finally prepare multileveled Mo WSe_(2)/WO_(3)/C anode materials with core-shell petal like curled nanosheet structure.Between the petal(MoSe_(2))-core(WO_(3))structure,the formation of WSe_(2)flakes by partial selenization on the surface of WO_(3)serves as a heterogeneous connection between MoSe_(2)and WO_(3).The enlarged layer distance(0.677 nm)between MoSe_(2)and WSe_(2)can facilitate the rapid transfer of Na+and electrons.The density functional theory(DFT)calculations verify that the Mo WSe_(2)/WO_(3)/C heterostructure performs excellent metallic properties.Ex-situ X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and transmission electron microscopy(TEM)confirm the activation process from the initial insertion reaction to the later conversion reaction.Resultantly,when employed as the anode of SIBs,a remarkable capacity of 384.3 mA h g-1after 950 cycles at 10 A g^(-1)is performed.Furthermore,the SICs assembled with commercial activated carbon(AC)as the cathode exhibits a remarkable energy density of 81.86 W h kg^(-1)(at 190 W kg^(-1))and 72.83 W h kg^(-1)(at 3800 W kg^(-1)).The unique structural design and the reaction investigation of the electrode process can provide a reference for the development of transition metal chalcogenides anodes.展开更多
Mowing is an important land management practice for natural semi-arid regions. A growing body of empirical evidence shows that different mowing regimes affect the functioning of grassland ecosystems. However, the resp...Mowing is an important land management practice for natural semi-arid regions. A growing body of empirical evidence shows that different mowing regimes affect the functioning of grassland ecosystems. However, the responses of plant functional traits to long-term mowing and their allometric scaling under long-term mowing are poorly understood. For a better understanding of the effects of mowing on grassland ecosystems, we analyzed the allometric traits of leaves and stems of Leymus chinensis （Trin.） Tzvel., a dominant grass species in eastern Eurasian temperate grassland, at different mowing intensities （no clipping, clipping once every two years, once a year and twice a year）. Experiments were conducted on plots established over a decade ago in a typical steppe of Xilinhot, Inner Mongolia, China. Results showed that most of the functional traits of L. chinensis decreased with the increased mowing intensity. The responses of leaves and stems to long-term mowing were asymmetric, in which leaf traits were more stable than stem traits. Also significant allometric relationships were found among most of the plant functional traits under the four mowing treatments. Sensitive traits of L. chinensis （e.g. leaf length and stem length） were primary indicators associated with aboveground biomass decline under high mowing intensity. In conclusion, the allometric growth of different functional traits of L. chinensis varies with different long-term mowing practices, which is likely to be a strategy used by the plant to adapt to the mowing disturbances.展开更多
The soil biological activity of mountain meadows is a significant factor that determines the health and utility of these regions. The climax stage of this area is forest, but to maintain semi-natural grassland, which ...The soil biological activity of mountain meadows is a significant factor that determines the health and utility of these regions. The climax stage of this area is forest, but to maintain semi-natural grassland, which is characterised by high biodiversity,low-intensity land use(mowing or grazing) is necessarily required. To understand the effect of various mowing regimes on the soil biological activity and plants, the soil microbial activity(microbial biomass carbon, dehydrogenase activity and number of the cultivable fraction of soil microbial community),annelids community(density and species composition earthworms and enchytraeids) and plant species composition were investigated. The study area was located in the Pieniny National Park in the Carpathian Mountains, in a meadow belonging to the association Dactylis glomerata-Poa trivialis. The investigated variants were divided according to mowing regime:traditional scything – hand mowing(HM), mechanical mowing(MM), or the abandonment of mowing – nonmowing(NM). The microbial activities(expressed by,e.g. microbial biomass carbon and the number of phosphorus bacteria) were affected by the mowing regime. The density of earthworms was higher in the HM and MM than in the NM variants. The largest changes in plant species composition were caused by the abandonment of mowing(NM). The mean number of plant species was positively correlated with soil moisture, earthworm density, and microbial activity(expressed indirectly by dehydrogenases activity). The soil microbial community, such as vegetative bacteria forms and ammonifying bacteria,were positively associated with pH value, and the microbial and total organic carbon content. The results presented here indicate that there is no single form of optimal management for all living organisms.Decisions about mowing regimes, or abandonment of use, should be preceded by multi-aspect studies,including plants and soil biota.展开更多
Grazing and mowing are two common practices for grassland management. Mowing is now recommended as an alternative to the traditional grazing for grassland conservation in Inner Mongolia, northern China. Many studies h...Grazing and mowing are two common practices for grassland management. Mowing is now recommended as an alternative to the traditional grazing for grassland conservation in Inner Mongolia, northern China. Many studies have revealed that mowing may alter ecosystem properties in various ways. However, little attention has been paid to the effect of mowing on trace gas emissions, especially on N2O flux. We conducted an experiment to investigate the effects of mowing on N2O fluxes from the semiarid grassland in Inner Mongolia. The mowing experiment, which started in 2003, comprised four mowing intensity treatments, i.e. mowing heights at 2 cm, 5 cm, 10 cm and 15 cm above the soil surface, respectively, and a control (non-mowing), with five replicates. Gas fluxes were measured through a closed static chamber technique during the growing seasons (usually from May to September, depending on local climate at the time) of 2008 and 2009, respectively. Our results showed that mowing decreased N2O emissions, above-ground biomass and total litter production. N2O emissions were greater in May and June than in other sampling periods, regardless of treatments (P 2O fluxes were mainly driven by variations in soil moisture, except in July and August. In July and August, above-ground plant biomass and soil total nitrogen became the major drivers of N2O fluxes under the soil temperatures between 16 ° C and 18 ° C. Though there were some uncertainties due to the low frequency of N2O flux measurement, our study mainly indicated that 5 cm mowing height might decrease N2O emissions in grasslands during the growing season, and soil properties affected the magnitude of the reduction.展开更多
Asphalt mow strips are typically used as vegetation barriers around guardrail posts in the design of roadside safety structures. Asphalt mow strips have historically been modeled as a rigid layer in simulations;this a...Asphalt mow strips are typically used as vegetation barriers around guardrail posts in the design of roadside safety structures. Asphalt mow strips have historically been modeled as a rigid layer in simulations;this assumption results in significant ground level restraint on the guardrail post. However, experiments have shown that asphalt rupture should be considered in the analysis of the response of guardrail posts embedded in mow strips. The present study investigates the effect of asphalt material properties and mow strip geometry on guardrail post performance using finite element simulations. Numerical simulations are performed and correlated with results from static experiments and material testing. The test simulations and experimental results are used to evaluate the response of guardrail posts with various mow strip designs to predict the level of restraint from the asphalt layer. The model is then used to investigate the effects of asphalt material properties and mow strip geometry on the overall performance of the system. The results demonstrate that including asphalt rupture in numerical simulations is essential in accurately predicting the behavior of guardrail posts installed in asphalt mow strips. In addition, mow strip geometry along with asphalt material properties significantly affect the guardrail post response.展开更多
Effects of mowing on the composition and diversity of grasslands varied with climate change(e.g.,precipitation and temperature).However,the interactive effects of long-term mowing and climate change on the diversity a...Effects of mowing on the composition and diversity of grasslands varied with climate change(e.g.,precipitation and temperature).However,the interactive effects of long-term mowing and climate change on the diversity and stability of leguminous and non-leguminous species in the semi-arid grasslands are largely unknown.Here,we used in situ monitoring data from 1982 to 2011 to examine the effects of continuous mowing and climate change on the plant biomass and diversity of leguminous and non-leguminous species,and soil total nitrogen in the typical semi-arid grasslands of northern China.Results showed that the biomass and diversity of leguminous species significantly decreased with the increasing in the biomass and diversity of non-leguminous species during the 30-a period.Variations in biomass were mainly affected by the long-term mowing,while variations in diversity were mainly explained by the climate change.Moreover,the normalized change rates of diversity in leguminous species were significantly higher than those in non-leguminous species.Mowing and temperature together contributed to the diversity changes of leguminous species,with mowing accounting for 50.0%and temperature 28.0%.Temporal stability of leguminous species was substantially lower than that of non-leguminous species.Consequently,soil total nitrogen decreased in the 2000s compared with the 1980s.These findings demonstrated that leguminous species were more sensitive to the long-term mowing and climate change than non-leguminous species in the semi-arid grasslands.Thus,reseeding appropriate leguminous plants when mowing in the semi-arid grasslands may be a better strategy to improve nitrogen levels of grassland ecosystems and maintain ecosystem biodiversity.展开更多
基金supported by the National Natural Science Foundation of China(22008053,52002111)the Key Research and Development Program of Hebei Province(20310601D,205A4401D)the Ministry of Higher Education of Malaysia for the Fundamental Research Grant(FRGS/1/2018/STG02/UM/02/10)awarded to Woo Haw Jiunn and University of Malaya research grant(GPF 038B-2018)。
文摘Exploring anode materials with high energy and power density is one of the critical milestones in developing sodium-ion batteries/capacitors(SIBs/SICs).Here,the Mo and W-based bimetallic organic framework(Mo-W-MOF)with core-shell structure is first formed by a facile strategy,followed by a selenization and carbonization strategy to finally prepare multileveled Mo WSe_(2)/WO_(3)/C anode materials with core-shell petal like curled nanosheet structure.Between the petal(MoSe_(2))-core(WO_(3))structure,the formation of WSe_(2)flakes by partial selenization on the surface of WO_(3)serves as a heterogeneous connection between MoSe_(2)and WO_(3).The enlarged layer distance(0.677 nm)between MoSe_(2)and WSe_(2)can facilitate the rapid transfer of Na+and electrons.The density functional theory(DFT)calculations verify that the Mo WSe_(2)/WO_(3)/C heterostructure performs excellent metallic properties.Ex-situ X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and transmission electron microscopy(TEM)confirm the activation process from the initial insertion reaction to the later conversion reaction.Resultantly,when employed as the anode of SIBs,a remarkable capacity of 384.3 mA h g-1after 950 cycles at 10 A g^(-1)is performed.Furthermore,the SICs assembled with commercial activated carbon(AC)as the cathode exhibits a remarkable energy density of 81.86 W h kg^(-1)(at 190 W kg^(-1))and 72.83 W h kg^(-1)(at 3800 W kg^(-1)).The unique structural design and the reaction investigation of the electrode process can provide a reference for the development of transition metal chalcogenides anodes.
基金financially supported by the National Basic Research Program of China(2014CB138806)the Natural Science Fund Project of Inner Mongolia(2015ZD02)+2 种基金the International Science and Technology Cooperation Program of China(2013DFR30760)the National Scientific and Technical Support Program of China(2012BAD12B02)the Special Fund for Agro-scientific Research in the Public Interest(201303060)
文摘Mowing is an important land management practice for natural semi-arid regions. A growing body of empirical evidence shows that different mowing regimes affect the functioning of grassland ecosystems. However, the responses of plant functional traits to long-term mowing and their allometric scaling under long-term mowing are poorly understood. For a better understanding of the effects of mowing on grassland ecosystems, we analyzed the allometric traits of leaves and stems of Leymus chinensis （Trin.） Tzvel., a dominant grass species in eastern Eurasian temperate grassland, at different mowing intensities （no clipping, clipping once every two years, once a year and twice a year）. Experiments were conducted on plots established over a decade ago in a typical steppe of Xilinhot, Inner Mongolia, China. Results showed that most of the functional traits of L. chinensis decreased with the increased mowing intensity. The responses of leaves and stems to long-term mowing were asymmetric, in which leaf traits were more stable than stem traits. Also significant allometric relationships were found among most of the plant functional traits under the four mowing treatments. Sensitive traits of L. chinensis （e.g. leaf length and stem length） were primary indicators associated with aboveground biomass decline under high mowing intensity. In conclusion, the allometric growth of different functional traits of L. chinensis varies with different long-term mowing practices, which is likely to be a strategy used by the plant to adapt to the mowing disturbances.
基金financed by the Ministry of Science and High Education of the Republic of Poland(No.BM–4162/15,4175/17 and DS3337/KEKiOP)
文摘The soil biological activity of mountain meadows is a significant factor that determines the health and utility of these regions. The climax stage of this area is forest, but to maintain semi-natural grassland, which is characterised by high biodiversity,low-intensity land use(mowing or grazing) is necessarily required. To understand the effect of various mowing regimes on the soil biological activity and plants, the soil microbial activity(microbial biomass carbon, dehydrogenase activity and number of the cultivable fraction of soil microbial community),annelids community(density and species composition earthworms and enchytraeids) and plant species composition were investigated. The study area was located in the Pieniny National Park in the Carpathian Mountains, in a meadow belonging to the association Dactylis glomerata-Poa trivialis. The investigated variants were divided according to mowing regime:traditional scything – hand mowing(HM), mechanical mowing(MM), or the abandonment of mowing – nonmowing(NM). The microbial activities(expressed by,e.g. microbial biomass carbon and the number of phosphorus bacteria) were affected by the mowing regime. The density of earthworms was higher in the HM and MM than in the NM variants. The largest changes in plant species composition were caused by the abandonment of mowing(NM). The mean number of plant species was positively correlated with soil moisture, earthworm density, and microbial activity(expressed indirectly by dehydrogenases activity). The soil microbial community, such as vegetative bacteria forms and ammonifying bacteria,were positively associated with pH value, and the microbial and total organic carbon content. The results presented here indicate that there is no single form of optimal management for all living organisms.Decisions about mowing regimes, or abandonment of use, should be preceded by multi-aspect studies,including plants and soil biota.
文摘Grazing and mowing are two common practices for grassland management. Mowing is now recommended as an alternative to the traditional grazing for grassland conservation in Inner Mongolia, northern China. Many studies have revealed that mowing may alter ecosystem properties in various ways. However, little attention has been paid to the effect of mowing on trace gas emissions, especially on N2O flux. We conducted an experiment to investigate the effects of mowing on N2O fluxes from the semiarid grassland in Inner Mongolia. The mowing experiment, which started in 2003, comprised four mowing intensity treatments, i.e. mowing heights at 2 cm, 5 cm, 10 cm and 15 cm above the soil surface, respectively, and a control (non-mowing), with five replicates. Gas fluxes were measured through a closed static chamber technique during the growing seasons (usually from May to September, depending on local climate at the time) of 2008 and 2009, respectively. Our results showed that mowing decreased N2O emissions, above-ground biomass and total litter production. N2O emissions were greater in May and June than in other sampling periods, regardless of treatments (P 2O fluxes were mainly driven by variations in soil moisture, except in July and August. In July and August, above-ground plant biomass and soil total nitrogen became the major drivers of N2O fluxes under the soil temperatures between 16 ° C and 18 ° C. Though there were some uncertainties due to the low frequency of N2O flux measurement, our study mainly indicated that 5 cm mowing height might decrease N2O emissions in grasslands during the growing season, and soil properties affected the magnitude of the reduction.
文摘Asphalt mow strips are typically used as vegetation barriers around guardrail posts in the design of roadside safety structures. Asphalt mow strips have historically been modeled as a rigid layer in simulations;this assumption results in significant ground level restraint on the guardrail post. However, experiments have shown that asphalt rupture should be considered in the analysis of the response of guardrail posts embedded in mow strips. The present study investigates the effect of asphalt material properties and mow strip geometry on guardrail post performance using finite element simulations. Numerical simulations are performed and correlated with results from static experiments and material testing. The test simulations and experimental results are used to evaluate the response of guardrail posts with various mow strip designs to predict the level of restraint from the asphalt layer. The model is then used to investigate the effects of asphalt material properties and mow strip geometry on the overall performance of the system. The results demonstrate that including asphalt rupture in numerical simulations is essential in accurately predicting the behavior of guardrail posts installed in asphalt mow strips. In addition, mow strip geometry along with asphalt material properties significantly affect the guardrail post response.
基金the National Key Research and Development Program of China(2016YFC0500604)the National Natural Science Foundation of China(31860681)+1 种基金the China Agriculture Research System(CARS-34)the Natural Science Foundation of Inner Mongolia Autonomous Region,China(2017MS0317).
文摘Effects of mowing on the composition and diversity of grasslands varied with climate change(e.g.,precipitation and temperature).However,the interactive effects of long-term mowing and climate change on the diversity and stability of leguminous and non-leguminous species in the semi-arid grasslands are largely unknown.Here,we used in situ monitoring data from 1982 to 2011 to examine the effects of continuous mowing and climate change on the plant biomass and diversity of leguminous and non-leguminous species,and soil total nitrogen in the typical semi-arid grasslands of northern China.Results showed that the biomass and diversity of leguminous species significantly decreased with the increasing in the biomass and diversity of non-leguminous species during the 30-a period.Variations in biomass were mainly affected by the long-term mowing,while variations in diversity were mainly explained by the climate change.Moreover,the normalized change rates of diversity in leguminous species were significantly higher than those in non-leguminous species.Mowing and temperature together contributed to the diversity changes of leguminous species,with mowing accounting for 50.0%and temperature 28.0%.Temporal stability of leguminous species was substantially lower than that of non-leguminous species.Consequently,soil total nitrogen decreased in the 2000s compared with the 1980s.These findings demonstrated that leguminous species were more sensitive to the long-term mowing and climate change than non-leguminous species in the semi-arid grasslands.Thus,reseeding appropriate leguminous plants when mowing in the semi-arid grasslands may be a better strategy to improve nitrogen levels of grassland ecosystems and maintain ecosystem biodiversity.
