Strengthening brand construction should be the starting point for the development of vegetable industry, and the key point of upgrading quality, enhancing efficiency and transforming the development pattern in Hebei P...Strengthening brand construction should be the starting point for the development of vegetable industry, and the key point of upgrading quality, enhancing efficiency and transforming the development pattern in Hebei Province. In view of the current situation of vegetable industry in Hebei Province, such as market saturation, quality upgrading, and the problems existing in the development of vegetable brands, some ideas and suggestions were put forward to strengthen the development of brand vegetables in Hebei Province.展开更多
Semiconductor colloidal nanocrystals(NCs)can interact with each other to profoundly influence the charge transfer,transport and extraction processes after they have been assembled into a high-density film for optoelec...Semiconductor colloidal nanocrystals(NCs)can interact with each other to profoundly influence the charge transfer,transport and extraction processes after they have been assembled into a high-density film for optoelectronic device applications.These interactions normally occur among several nearby single colloidal NCs,which should be effectively separated from their surroundings to remove the ensemble average effect for fine optical characterizations.By means of atomic force microscopy(AFM)nanoxerography,here we prepare individual clusters of perovskite CsPbBr3 NCs and perform single-particle measurements on their optical properties at the cryogenic temperature.While discrete photoluminescence bands can be resolved from the several single CsPbBr3 NCs that are contained within an individual cluster,the shorter-and longer-wavelength bands are dramatically different in that their intensities show sub-and superlinear dependences on the laser excitation powers,respectively.This can be explained by the generation of charged excitons(trions)at high laser excitation powers,and their subsequent Dexter-type energy transfer from smaller-to larger-sized CsPbBr3 NCs.Our findings not only suggest that these individual clusters prepared by AFM nanoxerography can serve as a potent platform to explore few-NC interactions but they also reveal the long-neglected role played by trions in channeling photo-excited energies among neighboring NCs.展开更多
In order to establish a supply system for energy resource coupled with the environment,the production technology of sugar beets was explored as a biological energy source. The low-humic andosol as the experimental soi...In order to establish a supply system for energy resource coupled with the environment,the production technology of sugar beets was explored as a biological energy source. The low-humic andosol as the experimental soil,the panting method was direct planting,and cultivation technique was minimum tillage direct planting method. The control was conventional tillage transplant and no tillage direct planting. The results demonstrated that data revealed that the energy cost of no tillage and a direct planting method was 105 GJ/hm2on average for two years,while that of the conventional tillage method was 112 GJ/hm2per year. The ratio of output to input showed that the direct planting with no tillage was more efficient( 3. 61) than the conventional tillage( 3. 01). Moreover,the emission of CO2into the atmosphere with no tillage and the direct planting was 71% of the conventional tillage planting technique. Therefore,direct planting without tillage reduces the impact on the environment.展开更多
Investigating the impacts of soil conversion on soil organic carbon(OC) content and its fractions within soil aggregates is essential for defining better strategies to improve soil structure and OC sequestration in te...Investigating the impacts of soil conversion on soil organic carbon(OC) content and its fractions within soil aggregates is essential for defining better strategies to improve soil structure and OC sequestration in terrestrial ecosystems. However, the consequences of soil conversion from paddy soil to upland soil for soil aggregates and intra-aggregate OC pools are poorly understood. Therefore, the objective of this study was to quantify the effects of soil conversion on soil aggregate and intra-aggregate OC pool distributions. Four typical rice-producing areas were chosen in North and South China, paired soil samples(upland soil converted from paddy soil more than ten years ago vs. adjacent paddy soil) were collected(0–20 cm) with three replicates in each area. A set of core parameters(OC preservation capacity, aggregate carbon(C) turnover, and biological activity index) were evaluated to assess the responses of intra-aggregate OC turnover to soil conversion. Results showed that soil conversion from paddy soil to upland soil significantly improved the formation of macro-aggregates and increased aggregate stability. It also notably decreased soil intra-aggregate OC pools, including easily oxidized OCa(EOCa), particulate OCa(POCa), and mineral-bound(MOCa) OC, and the sensitivity of aggregate-associated OC pools to soil conversion followed the order: EOCa(average reduction of 21.1%) > MOCa(average reduction of 15.4%) > POCa(average reduction of 14.8%). The potentially mineralizable C(C_(0)) was significantly higher in upland soil than in paddy soil, but the corresponding decay constant(k) was lower in upland soil than in paddy soil. Random forest model and partial correlation analysis showed that EOCa and pH were the important nutrient and physicochemical factors impacting k of C mineralization in paddy soil,while MOCa and C-related enzyme(β-D-cellobiohydrolase) were identified as the key factors in upland soil. In conclusion, this study evidenced that soil conversion from paddy soil to upland soil increased the percentage of macro-aggregates and aggregate stability, while decreased soil aggregate-associated C stock and k of soil C mineralization on a scale of ten years. Our findings provided some new insights into the alterations of soil aggregates and potential C sequestration under soil conversion system in rice-producing areas.展开更多
Harvesting of fresh-eating cherry tomato was highly costly on labor and time.In order to achieve mechanical harvesting for the fresh-eating tomato,a new harvesting robot was designed,which consisted of a stereo visual...Harvesting of fresh-eating cherry tomato was highly costly on labor and time.In order to achieve mechanical harvesting for the fresh-eating tomato,a new harvesting robot was designed,which consisted of a stereo visual unit,an end-effector,manipulator,a fruit collector,and a railed vehicle.The robot configuration and workflow design focused on the special cultivating condition.Three key parts were introduced in detail:a railroad vehicle capably moving on both ground and rail was adopted as the robot’s carrier,a visual servo unit was used to identify and locate the mature fruits bunch,and the end-effector to hold and separate the fruit bunch was designed based on the stalk’s mechanical features.The field test of the new developed robot was conducted and the results were analyzed.The successful harvest rate of the robot was 83%,however,each successful harvest averagely needed 1.4 times attempt,and a single successful harvesting cycle cost 8 s excluding the time cost on moving.展开更多
Semiconductor perovskite films are now being widely investigated as light harvesters in solar cells with ever-increasing power conversion efficiencies,which have motivated the fabrication of other optoelectronic devic...Semiconductor perovskite films are now being widely investigated as light harvesters in solar cells with ever-increasing power conversion efficiencies,which have motivated the fabrication of other optoelectronic devices,such as light-emitting diodes,lasers,and photodetectors.Their superior material and optical properties are shared by the counterpart colloidal nanocrystals(NCs),with the additional advantage of quantum confinement that can yield size-dependent optical emission ranging from the near-UV to near-infrared wavelengths.So far,intensive research efforts have been devoted to the optical characterization of perovskite NC ensembles,revealing not only fundamental exciton relaxation and recombination dynamics but also lowthreshold amplified spontaneous emission and novel superfluorescence effects.Meanwhile,the application of single-particle spectroscopy techniques to perovskite NCs has helped to resolve a variety of optical properties for which there are few equivalents in traditional colloidal NCs,mainly including nonblinking photoluminescence,suppressed spectral diffusion,stable exciton fine structures,and coherent singlephoton emission.While the main purpose of ensemble optical studies is to guide the smooth development of perovskite NCs in classical optoelectronic applications,the rich observations from single-particle optical studies mark the emergence of a potential platform that can be exploited for quantum information technologies.展开更多
文摘Strengthening brand construction should be the starting point for the development of vegetable industry, and the key point of upgrading quality, enhancing efficiency and transforming the development pattern in Hebei Province. In view of the current situation of vegetable industry in Hebei Province, such as market saturation, quality upgrading, and the problems existing in the development of vegetable brands, some ideas and suggestions were put forward to strengthen the development of brand vegetables in Hebei Province.
基金the National Key R&D Program of China(Grant Nos.2019YFA0308704 and 2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.61974058,11574147 and 11621091)the PAPD of Jiangsu Higher Education Institutions。
文摘Semiconductor colloidal nanocrystals(NCs)can interact with each other to profoundly influence the charge transfer,transport and extraction processes after they have been assembled into a high-density film for optoelectronic device applications.These interactions normally occur among several nearby single colloidal NCs,which should be effectively separated from their surroundings to remove the ensemble average effect for fine optical characterizations.By means of atomic force microscopy(AFM)nanoxerography,here we prepare individual clusters of perovskite CsPbBr3 NCs and perform single-particle measurements on their optical properties at the cryogenic temperature.While discrete photoluminescence bands can be resolved from the several single CsPbBr3 NCs that are contained within an individual cluster,the shorter-and longer-wavelength bands are dramatically different in that their intensities show sub-and superlinear dependences on the laser excitation powers,respectively.This can be explained by the generation of charged excitons(trions)at high laser excitation powers,and their subsequent Dexter-type energy transfer from smaller-to larger-sized CsPbBr3 NCs.Our findings not only suggest that these individual clusters prepared by AFM nanoxerography can serve as a potent platform to explore few-NC interactions but they also reveal the long-neglected role played by trions in channeling photo-excited energies among neighboring NCs.
基金the Scientific Research Foundation for the Returned OverseasChinese Scholars in Heilongjiang Province(LC08C30)
文摘In order to establish a supply system for energy resource coupled with the environment,the production technology of sugar beets was explored as a biological energy source. The low-humic andosol as the experimental soil,the panting method was direct planting,and cultivation technique was minimum tillage direct planting method. The control was conventional tillage transplant and no tillage direct planting. The results demonstrated that data revealed that the energy cost of no tillage and a direct planting method was 105 GJ/hm2on average for two years,while that of the conventional tillage method was 112 GJ/hm2per year. The ratio of output to input showed that the direct planting with no tillage was more efficient( 3. 61) than the conventional tillage( 3. 01). Moreover,the emission of CO2into the atmosphere with no tillage and the direct planting was 71% of the conventional tillage planting technique. Therefore,direct planting without tillage reduces the impact on the environment.
基金jointly supported by the National Natural Science Foundation of China(No.41161047)the Scientific Development and Technology Innovation Project of Xinjiang Production and Construction Group(XPCG)in China(No.2017BA041)。
文摘Investigating the impacts of soil conversion on soil organic carbon(OC) content and its fractions within soil aggregates is essential for defining better strategies to improve soil structure and OC sequestration in terrestrial ecosystems. However, the consequences of soil conversion from paddy soil to upland soil for soil aggregates and intra-aggregate OC pools are poorly understood. Therefore, the objective of this study was to quantify the effects of soil conversion on soil aggregate and intra-aggregate OC pool distributions. Four typical rice-producing areas were chosen in North and South China, paired soil samples(upland soil converted from paddy soil more than ten years ago vs. adjacent paddy soil) were collected(0–20 cm) with three replicates in each area. A set of core parameters(OC preservation capacity, aggregate carbon(C) turnover, and biological activity index) were evaluated to assess the responses of intra-aggregate OC turnover to soil conversion. Results showed that soil conversion from paddy soil to upland soil significantly improved the formation of macro-aggregates and increased aggregate stability. It also notably decreased soil intra-aggregate OC pools, including easily oxidized OCa(EOCa), particulate OCa(POCa), and mineral-bound(MOCa) OC, and the sensitivity of aggregate-associated OC pools to soil conversion followed the order: EOCa(average reduction of 21.1%) > MOCa(average reduction of 15.4%) > POCa(average reduction of 14.8%). The potentially mineralizable C(C_(0)) was significantly higher in upland soil than in paddy soil, but the corresponding decay constant(k) was lower in upland soil than in paddy soil. Random forest model and partial correlation analysis showed that EOCa and pH were the important nutrient and physicochemical factors impacting k of C mineralization in paddy soil,while MOCa and C-related enzyme(β-D-cellobiohydrolase) were identified as the key factors in upland soil. In conclusion, this study evidenced that soil conversion from paddy soil to upland soil increased the percentage of macro-aggregates and aggregate stability, while decreased soil aggregate-associated C stock and k of soil C mineralization on a scale of ten years. Our findings provided some new insights into the alterations of soil aggregates and potential C sequestration under soil conversion system in rice-producing areas.
基金We acknowledge that this work was financially supported by the National Natural Science Foundation of China(61703048)Beijing Excellent Talent Training to Support Young Key Individual Projects(2015000020060G134)BAAFS Youth Research Fund(QNJJ201722).
文摘Harvesting of fresh-eating cherry tomato was highly costly on labor and time.In order to achieve mechanical harvesting for the fresh-eating tomato,a new harvesting robot was designed,which consisted of a stereo visual unit,an end-effector,manipulator,a fruit collector,and a railed vehicle.The robot configuration and workflow design focused on the special cultivating condition.Three key parts were introduced in detail:a railroad vehicle capably moving on both ground and rail was adopted as the robot’s carrier,a visual servo unit was used to identify and locate the mature fruits bunch,and the end-effector to hold and separate the fruit bunch was designed based on the stalk’s mechanical features.The field test of the new developed robot was conducted and the results were analyzed.The successful harvest rate of the robot was 83%,however,each successful harvest averagely needed 1.4 times attempt,and a single successful harvesting cycle cost 8 s excluding the time cost on moving.
基金supported by the National Key R&D Program of China(Grant Nos.2019YFA0308700 and 2017YFA0303700)the National Natural Science Foundation of China(Grant Nos.61974058,11574147,and 11974164)the PAPD of Jiangsu Higher Education Institutions
文摘Semiconductor perovskite films are now being widely investigated as light harvesters in solar cells with ever-increasing power conversion efficiencies,which have motivated the fabrication of other optoelectronic devices,such as light-emitting diodes,lasers,and photodetectors.Their superior material and optical properties are shared by the counterpart colloidal nanocrystals(NCs),with the additional advantage of quantum confinement that can yield size-dependent optical emission ranging from the near-UV to near-infrared wavelengths.So far,intensive research efforts have been devoted to the optical characterization of perovskite NC ensembles,revealing not only fundamental exciton relaxation and recombination dynamics but also lowthreshold amplified spontaneous emission and novel superfluorescence effects.Meanwhile,the application of single-particle spectroscopy techniques to perovskite NCs has helped to resolve a variety of optical properties for which there are few equivalents in traditional colloidal NCs,mainly including nonblinking photoluminescence,suppressed spectral diffusion,stable exciton fine structures,and coherent singlephoton emission.While the main purpose of ensemble optical studies is to guide the smooth development of perovskite NCs in classical optoelectronic applications,the rich observations from single-particle optical studies mark the emergence of a potential platform that can be exploited for quantum information technologies.
