In recent decades,the spatio-temporal patterns of China’s croplands have been reshaped by disturbances from anthropogenic activities,with complex changes in the topographic characteristics of croplands.Slope-climbing...In recent decades,the spatio-temporal patterns of China’s croplands have been reshaped by disturbances from anthropogenic activities,with complex changes in the topographic characteristics of croplands.Slope-climbing of croplands(SCCL)is an important issue that threatens sustainable agricultural development.While providing land with prominent location advantages,SCCL weakens the water and fertilizer retention capacity for cropland,intensifies various geological disasters,and adversely affects the ecological environment and food yield of these croplands.It is crucial to determine the spatio-temporal variation features and effects of SCCL in China to formulate more accurate cropland protection policies and to maintain food security;however,the current lack of relevant studies is detrimental for capturing trends in cropland resources and sustainable cropland use.In this study,we constructed a multi-scale slope spectrum for cropland and total terrain to explore the spatial differences and trends of SCCL from a three-dimensional view.We evaluated the natural and socioeconomic effects of SCCL in China from multiple perspectives.Results indicate that the proportion of cropland with slopes below 2°,5°,and 6°in China decreased by 0.43%,0.47%,and 0.50%from 1980 to 2020,respectively.SCCL became apparent during 1980-1990 and 2010-2020,especially over the recent decade.The cropland climbing index(CCI)and upper limited slope change(ULSC)to measure the spatio-temporal pattern of SCCL were 0.99%and 1.17°,respectively,during 2010-2020.At the agricultural regional scale,the SCCL was also concentrated in 1980-1990 and 2010-2020,and it is more pronounced in the southern areas.The proportion of provinces and prefecture-level cities with high-intensity SCCL during 1980-2020 were 87.10%and 49.73%,respectively.SCCL was comparatively more pronounced and broader from 2010 to 2020.During this period,17.84%of prefecture-level cities had no SCCL,and the average CCI for all prefecture-level cities peaked at 1.62%.In this study,we also evaluated the pros and cons of SCCL and provided targeted suggestions for decision makers and farmers to refine cropland protection policy systems and further develop the sustainable use of croplands.展开更多
Cement is widely used in engineering applications,but it has both the characteristics of high brittleness and poor bending resistance.In this paper,the effects of different amounts ofgraphene oxide on the flexural str...Cement is widely used in engineering applications,but it has both the characteristics of high brittleness and poor bending resistance.In this paper,the effects of different amounts ofgraphene oxide on the flexural strength and compressive strength of cement mortar were studied by doping a certain amount of graphene oxide with cement mortar,and the strengthening mechanism of graphene oxide on cement mortar was obtained through microstructure detection.It is found that graphene oxide has a significant enhancement effect on the macroscopic mechanical properties of cement mortar,and graphene oxide provides nano-nucleation sites and growth templates for cement mortar,accelerates the hydration process,reduces the voids between hydration products,greatly increases the compactness,and improves the macroscopic properties of cement-based materials.展开更多
背景与目的气腔扩散(spread through air spaces,STAS)作为一种新发现的肺癌侵袭方式,其生物学特点及分子特征尚存在争议。本研究旨在探讨STAS与肺浸润性腺癌临床病理学特征及基因改变的关系。方法选取广州医科大学附属第一医院2019年7...背景与目的气腔扩散(spread through air spaces,STAS)作为一种新发现的肺癌侵袭方式,其生物学特点及分子特征尚存在争议。本研究旨在探讨STAS与肺浸润性腺癌临床病理学特征及基因改变的关系。方法选取广州医科大学附属第一医院2019年7月至2021年3月确诊的肺非黏液性浸润性腺癌手术切除标本694例,分析STAS与临床病理因素之间的关系。应用免疫组织化学方法检测间变性淋巴瘤激酶(anaplastic lymphoma kinase,ALK)蛋白表达;应用扩增阻滞突变系统-聚合酶链反应(amplification refractory mutation system-polymerase chain reaction,ARMS-PCR)技术检测表皮生长因子受体(epidermal growth factor receptor,EGFR)基因突变;应用反转录-PCR(reverse transcription-PCR,RT-PCR)技术检测肉瘤致癌因子受体(ROS proto-oncogene 1-receptor,ROS1)基因融合。结果STAS阳性病例共344例,STAS阴性病例共350例。STAS阳性与肿瘤最大径(P<0.001)、胸膜侵犯(P<0.001)、脉管侵犯(P<0.001)、神经束侵犯(P=0.013)、淋巴结转移(P<0.001)、临床分期(P<0.001)及组织学分型(P<0.001)相关;STAS与ALK蛋白表达(P<0.001)相关。多因素分析表明,STAS阳性与胸膜侵犯(P=0.001)、脉管侵犯(P<0.001)、淋巴结转移(P=0.005)及ALK蛋白表达(P=0.032)相关。结论STAS阳性与肺腺癌高侵袭性生物学行为有关,提示不良预后。展开更多
The extraction of lithium from salt lakes or seawater has attracted worldwide attention because of the explosive growth of global demand for lithium products. The LiMn_(2)O_(4)-based electrochemical lithium recovery s...The extraction of lithium from salt lakes or seawater has attracted worldwide attention because of the explosive growth of global demand for lithium products. The LiMn_(2)O_(4)-based electrochemical lithium recovery system is one of the strongest candidates for commercial application due to its high inserted capacity and low energy consumption. However, the surface orientation of LiMn_(2)O_(4)that facilitates Li diffusion happens to be prone to manganese dissolution making it a great challenge to obtain high lithium inserted capacity and long life simultaneously. Herein, we address this problem by designing a truncated octahedral LiMn_(2)O_(4)(Tr-oh LMO) in which the dominant(111) facets minimize Mn dissolution while a small portion of(100) facets facilitate the Li diffusion. Thus, this Tr-oh LMO-based electrochemical lithium recovery system shows excellent Li recovery performance with high inserted capacity(20.25 mg g^(-1)per cycle) in simulated brine. In addition, the dissolution rate of manganese per 30 cycles is only 0.44% and the capacity maintained 85% of the initial after 30 cycles. These promising findings accelerate the practical application of LiMn_(2)O_(4)in electrochemical lithium recovery.展开更多
Si is a promising anode material for Li ion batteries because of its high specific capacity,abundant reserve,and low cost.However,its rate performance and cycling stability are poor due to the severe particle pulveriz...Si is a promising anode material for Li ion batteries because of its high specific capacity,abundant reserve,and low cost.However,its rate performance and cycling stability are poor due to the severe particle pulverization during the lithiation/delithiation process.The high stress induced by the Li concentration gradient and anisotropic deformation is the main reason for the fracture of Si particles.Here we present a new stress mitigation strategy by uniformly distributing small amounts of Sn and Sb in Si micron-sized particles,which reduces the Li concentration gradient and realizes an isotropic lithiation/delithiation process.The Si8.5Sn0.5Sb microparticles(mean particle size:8.22μm)show over 6000-fold and tenfold improvements in electronic conductivity and Li diffusivity than Si particles,respectively.The discharge capacities of the Si_(8.5)Sn_(0.5)Sb microparticle anode after 100 cycles at 1.0 and 3.0 A g^(-1)are 1.62 and 1.19 Ah g^(-1),respectively,corresponding to a retention rate of 94.2%and 99.6%,respectively,relative to the capacity of the first cycle after activation.Multicomponent microparticle anodes containing Si,Sn,Sb,Ge and Ag prepared using the same method yields an ultra-low capacity decay rate of 0.02%per cycle for 1000 cycles at 1 A g^(-1),corroborating the proposed mechanism.The stress regulation mechanism enabled by the industry-compatible fabrication methods opens up enormous opportunities for low-cost and high-energy-density Li-ion batteries.展开更多
随着无人机技术的发展,利用无人机影像进行地形三维重建和全景影像生成,已经越来越普及。然而由于无人机影像拍摄时角度、光照条件、相机设置等具有不一致性,多视角无人机影像间通常存在一定的颜色差异。颜色差异的存在,会影响多视影像...随着无人机技术的发展,利用无人机影像进行地形三维重建和全景影像生成,已经越来越普及。然而由于无人机影像拍摄时角度、光照条件、相机设置等具有不一致性,多视角无人机影像间通常存在一定的颜色差异。颜色差异的存在,会影响多视影像密集匹配的精度,从而影响三维几何模型的精度。此外,颜色差异也会影响全景影像和纹理模型的视觉效果,拼接后影像及纹理模型上易出现“鬼影”及颜色拼接缝等问题。为解决该问题,本文提出一种无人机多视影像颜色一致性处理方法。首先,采用Structure from Motion (SfM)方法获取无人机影像间的所有匹配点;其次,构建并简化多视角无人机影像拓扑关系图;最后,基于颜色对应关系全局优化所有影像的颜色映射模型,获得匀色后影像。通过真实数据集进行实验,验证了本文提出的色彩一致性处理方法的有效性。展开更多
基金This research was supported in part by grants from the Natural Science Foundation of China(Grant No.42371258 and 42001187)The project was also supported by the Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region,Ministry of Natural Resources(NRMSSHR2023Y02)Yunnan Key Laboratory of Plateau Geographic Processes and Environmental Changes,Faculty of Geography,Yunnan Normal University(PGPEC2304).
文摘In recent decades,the spatio-temporal patterns of China’s croplands have been reshaped by disturbances from anthropogenic activities,with complex changes in the topographic characteristics of croplands.Slope-climbing of croplands(SCCL)is an important issue that threatens sustainable agricultural development.While providing land with prominent location advantages,SCCL weakens the water and fertilizer retention capacity for cropland,intensifies various geological disasters,and adversely affects the ecological environment and food yield of these croplands.It is crucial to determine the spatio-temporal variation features and effects of SCCL in China to formulate more accurate cropland protection policies and to maintain food security;however,the current lack of relevant studies is detrimental for capturing trends in cropland resources and sustainable cropland use.In this study,we constructed a multi-scale slope spectrum for cropland and total terrain to explore the spatial differences and trends of SCCL from a three-dimensional view.We evaluated the natural and socioeconomic effects of SCCL in China from multiple perspectives.Results indicate that the proportion of cropland with slopes below 2°,5°,and 6°in China decreased by 0.43%,0.47%,and 0.50%from 1980 to 2020,respectively.SCCL became apparent during 1980-1990 and 2010-2020,especially over the recent decade.The cropland climbing index(CCI)and upper limited slope change(ULSC)to measure the spatio-temporal pattern of SCCL were 0.99%and 1.17°,respectively,during 2010-2020.At the agricultural regional scale,the SCCL was also concentrated in 1980-1990 and 2010-2020,and it is more pronounced in the southern areas.The proportion of provinces and prefecture-level cities with high-intensity SCCL during 1980-2020 were 87.10%and 49.73%,respectively.SCCL was comparatively more pronounced and broader from 2010 to 2020.During this period,17.84%of prefecture-level cities had no SCCL,and the average CCI for all prefecture-level cities peaked at 1.62%.In this study,we also evaluated the pros and cons of SCCL and provided targeted suggestions for decision makers and farmers to refine cropland protection policy systems and further develop the sustainable use of croplands.
基金This work were supported by Natural Science Foundation of Zhejiang Province(LQ23E080003)a Doctoral program of Zhejiang University of science and technology(F701104L08)The Special Fund Project of Zhejiang University of Science and Technology's Basic Scientific Research Business Expenses in 2023(2023QN016).
文摘Cement is widely used in engineering applications,but it has both the characteristics of high brittleness and poor bending resistance.In this paper,the effects of different amounts ofgraphene oxide on the flexural strength and compressive strength of cement mortar were studied by doping a certain amount of graphene oxide with cement mortar,and the strengthening mechanism of graphene oxide on cement mortar was obtained through microstructure detection.It is found that graphene oxide has a significant enhancement effect on the macroscopic mechanical properties of cement mortar,and graphene oxide provides nano-nucleation sites and growth templates for cement mortar,accelerates the hydration process,reduces the voids between hydration products,greatly increases the compactness,and improves the macroscopic properties of cement-based materials.
基金supported by the National Natural Science Foundation of China (21878133,21908082,22178154)the Natural Science Foundation of Jiangsu Province(BK20190854)+1 种基金the China Postdoctoral Science Foundation(2020M671364,2021M701472)the Science&Technology Foundation of Zhenjiang (GY2020027)。
文摘The extraction of lithium from salt lakes or seawater has attracted worldwide attention because of the explosive growth of global demand for lithium products. The LiMn_(2)O_(4)-based electrochemical lithium recovery system is one of the strongest candidates for commercial application due to its high inserted capacity and low energy consumption. However, the surface orientation of LiMn_(2)O_(4)that facilitates Li diffusion happens to be prone to manganese dissolution making it a great challenge to obtain high lithium inserted capacity and long life simultaneously. Herein, we address this problem by designing a truncated octahedral LiMn_(2)O_(4)(Tr-oh LMO) in which the dominant(111) facets minimize Mn dissolution while a small portion of(100) facets facilitate the Li diffusion. Thus, this Tr-oh LMO-based electrochemical lithium recovery system shows excellent Li recovery performance with high inserted capacity(20.25 mg g^(-1)per cycle) in simulated brine. In addition, the dissolution rate of manganese per 30 cycles is only 0.44% and the capacity maintained 85% of the initial after 30 cycles. These promising findings accelerate the practical application of LiMn_(2)O_(4)in electrochemical lithium recovery.
基金This work was supported by the General Research Fund scheme of the Hong Kong Research Grants Council(Project No.15227121)the Hong Kong Polytechnic University(ZVGH).
文摘Si is a promising anode material for Li ion batteries because of its high specific capacity,abundant reserve,and low cost.However,its rate performance and cycling stability are poor due to the severe particle pulverization during the lithiation/delithiation process.The high stress induced by the Li concentration gradient and anisotropic deformation is the main reason for the fracture of Si particles.Here we present a new stress mitigation strategy by uniformly distributing small amounts of Sn and Sb in Si micron-sized particles,which reduces the Li concentration gradient and realizes an isotropic lithiation/delithiation process.The Si8.5Sn0.5Sb microparticles(mean particle size:8.22μm)show over 6000-fold and tenfold improvements in electronic conductivity and Li diffusivity than Si particles,respectively.The discharge capacities of the Si_(8.5)Sn_(0.5)Sb microparticle anode after 100 cycles at 1.0 and 3.0 A g^(-1)are 1.62 and 1.19 Ah g^(-1),respectively,corresponding to a retention rate of 94.2%and 99.6%,respectively,relative to the capacity of the first cycle after activation.Multicomponent microparticle anodes containing Si,Sn,Sb,Ge and Ag prepared using the same method yields an ultra-low capacity decay rate of 0.02%per cycle for 1000 cycles at 1 A g^(-1),corroborating the proposed mechanism.The stress regulation mechanism enabled by the industry-compatible fabrication methods opens up enormous opportunities for low-cost and high-energy-density Li-ion batteries.
文摘随着无人机技术的发展,利用无人机影像进行地形三维重建和全景影像生成,已经越来越普及。然而由于无人机影像拍摄时角度、光照条件、相机设置等具有不一致性,多视角无人机影像间通常存在一定的颜色差异。颜色差异的存在,会影响多视影像密集匹配的精度,从而影响三维几何模型的精度。此外,颜色差异也会影响全景影像和纹理模型的视觉效果,拼接后影像及纹理模型上易出现“鬼影”及颜色拼接缝等问题。为解决该问题,本文提出一种无人机多视影像颜色一致性处理方法。首先,采用Structure from Motion (SfM)方法获取无人机影像间的所有匹配点;其次,构建并简化多视角无人机影像拓扑关系图;最后,基于颜色对应关系全局优化所有影像的颜色映射模型,获得匀色后影像。通过真实数据集进行实验,验证了本文提出的色彩一致性处理方法的有效性。
基金supported in part by the Key Laboratory of Icing and Anti/De-icing of CARDC(No.IADL 20210404)the National Natural Science Foun-dation of China(NSFC)(No.62275100)Jilin Province Development and Reform Commission Project(No.2022C047-4)。
