This paper describes the capability of remote sensing in the monitoring of rangeland vegetation productivities and dynamics in the foothill areas of Uzbekistan, in order to enhance the sustainable utilization of natur...This paper describes the capability of remote sensing in the monitoring of rangeland vegetation productivities and dynamics in the foothill areas of Uzbekistan, in order to enhance the sustainable utilization of natural resources. Seasonal productivity, including above-ground biomass, density, coverage, foliar chlorophyll, and carotene content, was measured for the Artemisia diffusa, the dominant species of the study area. The Normalized Difference Vegetation Index (NDVI), extracted from time-series Landsat TM5 satellite images, was used to obtain pertinent data regarding vegetation coverage and potential productivities. Seasonal precipitation was found to be a key factor in governing soil moisture in the semi-arid foothill rangelands, which directly influence the dynamics of plants and productivities. Precipitation and soil moisture determine the length of the plant growing season and further influence NDVI values. We found that time-series NDVI was significantly correlated with the seasonal green and total above-ground biomass of vegetation and coverage of Artemisia diffusa, soil moisture, and changeable nitrogen. We also found that the foliar chlorophylls of Artemisia diffusa was significantly correlated with the green above-ground biomass (r = 0.44, P < 0.05). The results can contribute to further monitoring of ecosystem health and habitat conditions using remote sensing (RS) as an accurate tool in large rangeland areas.展开更多
The compressive properties of epoxy with different silica nanoparticles (SiO2 nanoparticles) contents at quasi-static and high strain rates loading were investigated via experiment. This article evaluates the compress...The compressive properties of epoxy with different silica nanoparticles (SiO2 nanoparticles) contents at quasi-static and high strain rates loading were investigated via experiment. This article evaluates the compressive failure behaviors and modes at different SiO2 nanoparticles contents and different strain rates. The results indicated that the stress strain curves were sensitive to strain rate, and the compressive failure stress of composites with various SiO2 nanoparticles contents increased with the strain rates, and it increased along with SiO2 nanoparticles contents and then declined. The compressive failure stress and the compressive failure modes of the composites were apparently different from the change of SiO2 nanoparticles contents.展开更多
In the intelligent era,the textile technique is a high efficiency,mature and simple manufacturing solution capable of fabricat-ing fully flexible wearable devices.However,the external circuit with its integration and ...In the intelligent era,the textile technique is a high efficiency,mature and simple manufacturing solution capable of fabricat-ing fully flexible wearable devices.However,the external circuit with its integration and comfort limitations cannot satisfy the requirements of intelligent wearable and portable devices.This study presents an industrialized production method to fabricate core–shell structure conductive yarn for direct textile use,prepared by the high-speed sirospun technique.Both integration and flexibility are significantly improved over previous works.Combining sirospun conductive yarn(SSCY)and the intarsia technique can provide the SSCY seamless and convenient embedded knitted circuit(SSCY-EKC)to form a full textile electrical element as the channel of power and signals transmission,allowing for a stable resistance change and wide strain range for meeting practical applications.SSCY based on the triboelectric nanogenerator(SSCY-TENG)can be designed as a caution carpet with attractive design and good washability for a self-powered sensor that recognizes human motions.Furthermore,intrinsic textile properties such as washability,softness,and comfort remained.With benefits such as excellent extension,fitting,and stretchability,the SSCY-EKC used herein can realize a fully flexible electrical textile with a high potential for physical detection,body gesture recognition,apparel fashion,and decoration.展开更多
Combined effects of ozone （O3） and cadmium （Cd） on growth and physiology of winter wheat （Triticum aestivum L. cv. JM22） were determined. Wheat plants were grown without or with Cd and exposed to charcoal-filter...Combined effects of ozone （O3） and cadmium （Cd） on growth and physiology of winter wheat （Triticum aestivum L. cv. JM22） were determined. Wheat plants were grown without or with Cd and exposed to charcoal-filtered air （〈 10 ppb O3） or elevated O3 （80 ＋ 5 ppb, 7 hr/day） for 20 days. Results showed that O3 considerably depressed light saturated net photosynthetic rate （-20%）, stomatal conductance （-33%）, chlorophyll content （-33%）, and total biomass （-29%） without Cd. The corresponding decreases were further enhanced by 45%, 56%, 60% and 59%, respectively with Cd, indicating a synergistic effect of O3 and Cd on wheat. Ozone significantly increased the activity of superoxide dismutase （46%）, catalase （48%） and peroxidase （56%）. However, great increases in malondialdehyde （MDA） content （2.55 folds） and intercellular CO2 concentration （1.13 folds） were noted in O3＋Cd treatment compared to control. Our findings demonstrated that the increased anti-oxidative activities in wheat plants exposed to O3＋Cd might not be enough to overcome the adverse effects of the combination of both pollutants as evidenced by further increase in MDA content, which is an important indicator of lipid peroxidation. Precise prediction model on O3 damages to crop should be conducted to ensure agricultural production security by considering environmental constraints in an agricultural system in peri-urban regions.展开更多
Rhus typhina, an alien species introduced from North America, was identified as a main afforestation species in Beijing municipality. However, its invasiveness is still at odds. To clarify this problem, we applied the...Rhus typhina, an alien species introduced from North America, was identified as a main afforestation species in Beijing municipality. However, its invasiveness is still at odds. To clarify this problem, we applied the North American Screening System and the Australian Screening System to preliminarily predict its invasion possibility. Both screening systems gave the same recommendation to ＂reject＂. The geographical distribution was surveyed, with the population features of R. typhina against the native plant communities being assessed. With anthropogenic assistance, R. typhina has been scattered on almost all habitats from downtown to mountains, including roadsides, farmlands and protected areas. As a clonal shrub, R. typhina possessed a high spreading rate, varying from 6.3 m/3 years at sterile habitats to 6.7 m/3 years at fertile ones. Significantly lower species richness, individual density and diversity were observed in the R. typhina community than those of the native Vitex negundo Linn.var. heterophylla （Franch.） Rehd. community at both sterile and fertile habitats. Continual wide plantation of R. typhina may further foster its population expansion, which helps the species to overcome spatial isolation, The fact that each root fragment can develop into a new individual makes R. typhina very difficult to be eradicated once established. From a biological point of view, we believe that R. typhina is a plant invader in Beijing. We therefore suggest the government should remove the name of R. typhina from the main tree species list in afforesUng Beijing.展开更多
文摘This paper describes the capability of remote sensing in the monitoring of rangeland vegetation productivities and dynamics in the foothill areas of Uzbekistan, in order to enhance the sustainable utilization of natural resources. Seasonal productivity, including above-ground biomass, density, coverage, foliar chlorophyll, and carotene content, was measured for the Artemisia diffusa, the dominant species of the study area. The Normalized Difference Vegetation Index (NDVI), extracted from time-series Landsat TM5 satellite images, was used to obtain pertinent data regarding vegetation coverage and potential productivities. Seasonal precipitation was found to be a key factor in governing soil moisture in the semi-arid foothill rangelands, which directly influence the dynamics of plants and productivities. Precipitation and soil moisture determine the length of the plant growing season and further influence NDVI values. We found that time-series NDVI was significantly correlated with the seasonal green and total above-ground biomass of vegetation and coverage of Artemisia diffusa, soil moisture, and changeable nitrogen. We also found that the foliar chlorophylls of Artemisia diffusa was significantly correlated with the green above-ground biomass (r = 0.44, P < 0.05). The results can contribute to further monitoring of ecosystem health and habitat conditions using remote sensing (RS) as an accurate tool in large rangeland areas.
文摘The compressive properties of epoxy with different silica nanoparticles (SiO2 nanoparticles) contents at quasi-static and high strain rates loading were investigated via experiment. This article evaluates the compressive failure behaviors and modes at different SiO2 nanoparticles contents and different strain rates. The results indicated that the stress strain curves were sensitive to strain rate, and the compressive failure stress of composites with various SiO2 nanoparticles contents increased with the strain rates, and it increased along with SiO2 nanoparticles contents and then declined. The compressive failure stress and the compressive failure modes of the composites were apparently different from the change of SiO2 nanoparticles contents.
基金supported by the National Science Funds of China(11972172)the State Key Laboratory of New Textile Materials and Advanced Processing Technologies,No.FZ2021013+2 种基金the Fundamental Research Funds for the Central Universities(JUSRP122003)the Natural Science Foundation of Jiangsu Province(BK20221094)the Fundamental Research Funds for the Central Universities(JUSRP122003).
文摘In the intelligent era,the textile technique is a high efficiency,mature and simple manufacturing solution capable of fabricat-ing fully flexible wearable devices.However,the external circuit with its integration and comfort limitations cannot satisfy the requirements of intelligent wearable and portable devices.This study presents an industrialized production method to fabricate core–shell structure conductive yarn for direct textile use,prepared by the high-speed sirospun technique.Both integration and flexibility are significantly improved over previous works.Combining sirospun conductive yarn(SSCY)and the intarsia technique can provide the SSCY seamless and convenient embedded knitted circuit(SSCY-EKC)to form a full textile electrical element as the channel of power and signals transmission,allowing for a stable resistance change and wide strain range for meeting practical applications.SSCY based on the triboelectric nanogenerator(SSCY-TENG)can be designed as a caution carpet with attractive design and good washability for a self-powered sensor that recognizes human motions.Furthermore,intrinsic textile properties such as washability,softness,and comfort remained.With benefits such as excellent extension,fitting,and stretchability,the SSCY-EKC used herein can realize a fully flexible electrical textile with a high potential for physical detection,body gesture recognition,apparel fashion,and decoration.
基金jointly supported by the Key Strategic Project of the Chinese Academy of Sciences(KSZD-EW-Z-012-2)the National Science and Technology Support Program(2012BAD14B00)
基金supported by the Innovative Group Grant of Natural Science Foundation of China(No.30521002)the Project of Tai’shan Scholarship of Shandong Province of China(No. 00523902)
文摘Combined effects of ozone （O3） and cadmium （Cd） on growth and physiology of winter wheat （Triticum aestivum L. cv. JM22） were determined. Wheat plants were grown without or with Cd and exposed to charcoal-filtered air （〈 10 ppb O3） or elevated O3 （80 ＋ 5 ppb, 7 hr/day） for 20 days. Results showed that O3 considerably depressed light saturated net photosynthetic rate （-20%）, stomatal conductance （-33%）, chlorophyll content （-33%）, and total biomass （-29%） without Cd. The corresponding decreases were further enhanced by 45%, 56%, 60% and 59%, respectively with Cd, indicating a synergistic effect of O3 and Cd on wheat. Ozone significantly increased the activity of superoxide dismutase （46%）, catalase （48%） and peroxidase （56%）. However, great increases in malondialdehyde （MDA） content （2.55 folds） and intercellular CO2 concentration （1.13 folds） were noted in O3＋Cd treatment compared to control. Our findings demonstrated that the increased anti-oxidative activities in wheat plants exposed to O3＋Cd might not be enough to overcome the adverse effects of the combination of both pollutants as evidenced by further increase in MDA content, which is an important indicator of lipid peroxidation. Precise prediction model on O3 damages to crop should be conducted to ensure agricultural production security by considering environmental constraints in an agricultural system in peri-urban regions.
基金the Innovative Group Grant of the National Natural ScienceFoundation of China (30521002)Beijing Science and Technology Committee (H030630050490).
文摘Rhus typhina, an alien species introduced from North America, was identified as a main afforestation species in Beijing municipality. However, its invasiveness is still at odds. To clarify this problem, we applied the North American Screening System and the Australian Screening System to preliminarily predict its invasion possibility. Both screening systems gave the same recommendation to ＂reject＂. The geographical distribution was surveyed, with the population features of R. typhina against the native plant communities being assessed. With anthropogenic assistance, R. typhina has been scattered on almost all habitats from downtown to mountains, including roadsides, farmlands and protected areas. As a clonal shrub, R. typhina possessed a high spreading rate, varying from 6.3 m/3 years at sterile habitats to 6.7 m/3 years at fertile ones. Significantly lower species richness, individual density and diversity were observed in the R. typhina community than those of the native Vitex negundo Linn.var. heterophylla （Franch.） Rehd. community at both sterile and fertile habitats. Continual wide plantation of R. typhina may further foster its population expansion, which helps the species to overcome spatial isolation, The fact that each root fragment can develop into a new individual makes R. typhina very difficult to be eradicated once established. From a biological point of view, we believe that R. typhina is a plant invader in Beijing. We therefore suggest the government should remove the name of R. typhina from the main tree species list in afforesUng Beijing.
