Background:Accurate mapping of tree species is highly desired in the management and research of plantation forests,whose ecosystem services are currently under threats.Time-series multispectral satellite images,e.g.,f...Background:Accurate mapping of tree species is highly desired in the management and research of plantation forests,whose ecosystem services are currently under threats.Time-series multispectral satellite images,e.g.,from Landsat-8(L8)and Sentinel-2(S2),have been proven useful in mapping general forest types,yet we do not know quantitatively how their spectral features(e.g.,red-edge)and temporal frequency of data acquisitions(e.g.,16-day vs.5-day)contribute to plantation forest mapping to the species level.Moreover,it is unclear to what extent the fusion of L8 and S2 will result in improvements in tree species mapping of northern plantation forests in China.Methods:We designed three sets of classification experiments(i.e.,single-date,multi-date,and spectral-temporal)to evaluate the performances of L8 and S2 data for mapping keystone timber tree species in northern China.We first used seven pairs of L8 and S2 images to evaluate the performances of L8 and S2 key spectral features for separating these tree species across key growing stages.Then we extracted the spectral-temporal features from all available images of different temporal frequency of data acquisition(i.e.,L8 time series,S2 time series,and fusion of L8 and S2)to assess the contribution of image temporal frequency on the accuracy of tree species mapping in the study area.Results:1)S2 outperformed L8 images in all classification experiments,with or without the red edge bands(0.4%–3.4%and 0.2%–4.4%higher for overall accuracy and macro-F1,respectively);2)NDTI(the ratio of SWIR1 minus SWIR2 to SWIR1 plus SWIR2)and Tasseled Cap coefficients were most important features in all the classifications,and for time-series experiments,the spectral-temporal features of red band-related vegetation indices were most useful;3)increasing the temporal frequency of data acquisition can improve overall accuracy of tree species mapping for up to 3.2%(from 90.1%using single-date imagery to 93.3%using S2 time-series),yet similar overall accuracies were achieved using S2 time-series(93.3%)and the fusion of S2 and L8(93.2%).Conclusions:This study quantifies the contributions of L8 and S2 spectral and temporal features in mapping keystone tree species of northern plantation forests in China and suggests that for mapping tree species in China's northern plantation forests,the effects of increasing the temporal frequency of data acquisition could saturate quickly after using only two images from key phenological stages.展开更多
Eight new triterpenoids were isolated from Ainsliaea latifolia.The structures of these compounds were elucidated by interpretation of spectroscopic data,including HRESIMS and NMR data.Compounds 4–6 are identifed as r...Eight new triterpenoids were isolated from Ainsliaea latifolia.The structures of these compounds were elucidated by interpretation of spectroscopic data,including HRESIMS and NMR data.Compounds 4–6 are identifed as rare trinorcucurbitane or tetranorcucurbitane triterpenoids.The absolute confgurations of compounds 1 and 2 were confrmed by Snatzke’s method.All compounds were evaluated for their inhibition against cyclooxyenase-2(COX-2),in which compound 4 showed signifcant inhibitory efect against COX-2 with IC_(50) value of 3.98±0.32μM,comparable to that of positive control NS-398(IC504.14±0.28μM).展开更多
Although multiple microscopic techniques have been applied to horticultural research,few studies of individual organelles in living fruit cells have been reported to date.In this paper,we established an efficient syst...Although multiple microscopic techniques have been applied to horticultural research,few studies of individual organelles in living fruit cells have been reported to date.In this paper,we established an efficient system for the transient transformation of citrus fruits using an Agrobacterium-mediated method.Kumquat(Fortunella crassifolia Swingle)was used;it exhibits higher transformation efficiency than all citrus fruits that have been tested and a prolonged-expression window.Fruits were transformed with fluorescent reporters,and confocal microscopy and live-cell imaging were used to study their localization and dynamics.Moreover,various pH sensors targeting different subcellular compartments were expressed,and the local pH environments in cells from different plant tissues were compared.The results indicated that vacuoles are most likely the main organelles that contribute to the low pH of citrus fruits.In summary,our method is effective for studying various membrane trafficking events,protein localization,and cell physiology in fruit and can provide new insight into fruit biology research.展开更多
This paper presents the brief geological and mineralogical characteristics of the Dorozhnoye mesothermal gold ore deposit (Magadan Region, Russia). The gold and silver minerals are represented by electrum (530‰ - 700...This paper presents the brief geological and mineralogical characteristics of the Dorozhnoye mesothermal gold ore deposit (Magadan Region, Russia). The gold and silver minerals are represented by electrum (530‰ - 700‰), freibergite, stephanite, pyrargyrite and Bi-diaphorite. The homogeneous fluid inclusions enable one to determine that the quartz-molybdenite veins were formed at a temperature of 340°C to 140°C, and that the quartz-sulfide gold ore veins were formed at a temperature of 165°C to 125°C. It is assumed that the fluid had a mixed composition and evolved from K-chloride and K-carbonate to Na-chloride. The hypergenesis zone contains: high fineness gold (800‰ - 950‰), petrovskaite (AgAuS) and uytenbogaardtite (Ag3AuS2) associated with goethite and melanterite. The surface waters contain: Ca++ up to 293 mg/L, HCO3 up to 125 mg/L, SO4 up to 777 mg/L;рН is 5.8 to 7.2. Thermodynamic calculations have been conducted and Eh-pH diagrams have been built for the Au-Ag-S-H2O system at 25°C and 100°C (p = 1 bar) to reveal gold and silver stability fields. Au-Ag sulfides at the Dorozhnoye deposit are formed under oxidizing conditions and an acidic environment with dominating sulfates.展开更多
The sedimentary successions around the Carboniferous-Permian boundary(CPB)in the Ordos Basin were investigated using extensive outcrop,borehole,well logging,thin section,and geochemistry data to study sedimentary and ...The sedimentary successions around the Carboniferous-Permian boundary(CPB)in the Ordos Basin were investigated using extensive outcrop,borehole,well logging,thin section,and geochemistry data to study sedimentary and sequence stratigraphic responses to glaciation and volcanism in paleotropical transitional strata.Within the studied interval,five distinct lithofacies have been identified,including bauxite,coal,and carbonaceous shale(No.8+9 coal seams),sandstone(Qiaotou),limestone(Baode),and mudstone,which can be classified into three lithofacies associations.The most complete lithofacies associ-ation is composed of bauxite,coal,carbonaceous shale,sandstone,limestone/mudstone or their combinations from the bottom to the top,while coal and carbonaceous shale,as well as sandstone,are absent locally,resulting in the formation of the other two types of lithofacies associations.The occurrence of bauxite in-dicates shelf exposure and weathering,the occurrence of coal and carbonaceous shale indicates swampiness of the shelf,and the occurrence of sandstone reveals river rejuvenation;all of these are thought to be sedimentary responses to the transcontinental glacier expansion in Gondwana around the CPB.The presence of limestone and mudstone indicates carbonate platform and lagoon deposition,respectively,in the context of the earliest Asselian transgression caused by volcanism-induced glacier melting.The lithofacies associations record the regressive-transgressive cycles that occurred because of glaciation and volcanism near the CPB.The top surface of bauxite can be used as a sequence boundary,while the lowstand systems tract consists of the No.8+9 coal seams and the Qiaotou sandstone,and the transgressive systems tract consists of the overlying Baode limestone and laterally equivalent mudstone.The lowstand systems tract,which contains source rock and hydrocarbon reservoirs,and the overlying transgressive systems tract,which serves as cap rock,form an excellent source-reservoir-seal combination.展开更多
Dear Editor:RNA silencing confers immunity against most viruses and is initiated by host Dicer processing of viral doublestranded RNA into virus-derived small interfering RNA(siRNA)(Guo et al.,2019).Viruses that cause...Dear Editor:RNA silencing confers immunity against most viruses and is initiated by host Dicer processing of viral doublestranded RNA into virus-derived small interfering RNA(siRNA)(Guo et al.,2019).Viruses that cause plant disease usually evolve viral suppressor of RNA silencing(VSR)to inhibit antiviral silencing(Li and Ding,2006).Some plant nucleotide-binding leucine-rich repeat proteins(NLRs)emerge as immune receptors to recognize specific virus and trigger rapid hypersensitive response(HR)at infection site to protect plants from devastating viruses(Cui et al.,2015;Deng et al.,2018).Recent studies showed that NLR immune receptors are subjected to negative regulation by plant miRNAs(Deng et al.,2018).It is well known that in some cases,mixed virus infections lead to synergism in susceptible plants due to cooperative inhibition of antiviral silencing by multiple VSRs(Pruss et al.,1997).In case of mixed virus infection in a plant with NLR targeting a single virus,heterologous VSR might play dual roles for the NLR-targeted virus.On one hand,the VSR may promote virulence by cooperative inhibition of antiviral silencing.展开更多
基金supported by National Natural Science Foundation of China(Grant No.41901382)Open Fund of State Key Laboratory of Remote Sensing Science(Grant No.OFSLRSS201917)the HZAU research startup fund(No.11041810340,No.11041810341).
文摘Background:Accurate mapping of tree species is highly desired in the management and research of plantation forests,whose ecosystem services are currently under threats.Time-series multispectral satellite images,e.g.,from Landsat-8(L8)and Sentinel-2(S2),have been proven useful in mapping general forest types,yet we do not know quantitatively how their spectral features(e.g.,red-edge)and temporal frequency of data acquisitions(e.g.,16-day vs.5-day)contribute to plantation forest mapping to the species level.Moreover,it is unclear to what extent the fusion of L8 and S2 will result in improvements in tree species mapping of northern plantation forests in China.Methods:We designed three sets of classification experiments(i.e.,single-date,multi-date,and spectral-temporal)to evaluate the performances of L8 and S2 data for mapping keystone timber tree species in northern China.We first used seven pairs of L8 and S2 images to evaluate the performances of L8 and S2 key spectral features for separating these tree species across key growing stages.Then we extracted the spectral-temporal features from all available images of different temporal frequency of data acquisition(i.e.,L8 time series,S2 time series,and fusion of L8 and S2)to assess the contribution of image temporal frequency on the accuracy of tree species mapping in the study area.Results:1)S2 outperformed L8 images in all classification experiments,with or without the red edge bands(0.4%–3.4%and 0.2%–4.4%higher for overall accuracy and macro-F1,respectively);2)NDTI(the ratio of SWIR1 minus SWIR2 to SWIR1 plus SWIR2)and Tasseled Cap coefficients were most important features in all the classifications,and for time-series experiments,the spectral-temporal features of red band-related vegetation indices were most useful;3)increasing the temporal frequency of data acquisition can improve overall accuracy of tree species mapping for up to 3.2%(from 90.1%using single-date imagery to 93.3%using S2 time-series),yet similar overall accuracies were achieved using S2 time-series(93.3%)and the fusion of S2 and L8(93.2%).Conclusions:This study quantifies the contributions of L8 and S2 spectral and temporal features in mapping keystone tree species of northern plantation forests in China and suggests that for mapping tree species in China's northern plantation forests,the effects of increasing the temporal frequency of data acquisition could saturate quickly after using only two images from key phenological stages.
基金supported by NSFC(Nos.81573318,31870327,81230090,81520108030,1302658)National Major Project of China(No.2018ZX09731016-005)+2 种基金The Key Research and Development Program of China(Nos.2017YFC1702002,2017YFC1700200)Professor of Chang Jiang Scholars Program,Scientific Foundation of Shanghai China(Nos.17431902800,16401901300)Shanghai Engineering Research Center for the Preparation of Bioactive Natural Products(No.10DZ2251300).
文摘Eight new triterpenoids were isolated from Ainsliaea latifolia.The structures of these compounds were elucidated by interpretation of spectroscopic data,including HRESIMS and NMR data.Compounds 4–6 are identifed as rare trinorcucurbitane or tetranorcucurbitane triterpenoids.The absolute confgurations of compounds 1 and 2 were confrmed by Snatzke’s method.All compounds were evaluated for their inhibition against cyclooxyenase-2(COX-2),in which compound 4 showed signifcant inhibitory efect against COX-2 with IC_(50) value of 3.98±0.32μM,comparable to that of positive control NS-398(IC504.14±0.28μM).
基金This work was supported by the National Key Research and Development Program(2019YFD1000103)NSFC grants(no.31772281,91854102)to P.W.
文摘Although multiple microscopic techniques have been applied to horticultural research,few studies of individual organelles in living fruit cells have been reported to date.In this paper,we established an efficient system for the transient transformation of citrus fruits using an Agrobacterium-mediated method.Kumquat(Fortunella crassifolia Swingle)was used;it exhibits higher transformation efficiency than all citrus fruits that have been tested and a prolonged-expression window.Fruits were transformed with fluorescent reporters,and confocal microscopy and live-cell imaging were used to study their localization and dynamics.Moreover,various pH sensors targeting different subcellular compartments were expressed,and the local pH environments in cells from different plant tissues were compared.The results indicated that vacuoles are most likely the main organelles that contribute to the low pH of citrus fruits.In summary,our method is effective for studying various membrane trafficking events,protein localization,and cell physiology in fruit and can provide new insight into fruit biology research.
文摘This paper presents the brief geological and mineralogical characteristics of the Dorozhnoye mesothermal gold ore deposit (Magadan Region, Russia). The gold and silver minerals are represented by electrum (530‰ - 700‰), freibergite, stephanite, pyrargyrite and Bi-diaphorite. The homogeneous fluid inclusions enable one to determine that the quartz-molybdenite veins were formed at a temperature of 340°C to 140°C, and that the quartz-sulfide gold ore veins were formed at a temperature of 165°C to 125°C. It is assumed that the fluid had a mixed composition and evolved from K-chloride and K-carbonate to Na-chloride. The hypergenesis zone contains: high fineness gold (800‰ - 950‰), petrovskaite (AgAuS) and uytenbogaardtite (Ag3AuS2) associated with goethite and melanterite. The surface waters contain: Ca++ up to 293 mg/L, HCO3 up to 125 mg/L, SO4 up to 777 mg/L;рН is 5.8 to 7.2. Thermodynamic calculations have been conducted and Eh-pH diagrams have been built for the Au-Ag-S-H2O system at 25°C and 100°C (p = 1 bar) to reveal gold and silver stability fields. Au-Ag sulfides at the Dorozhnoye deposit are formed under oxidizing conditions and an acidic environment with dominating sulfates.
基金Science and Technology Research Project for University in Hebei Province (QN2022060)National Preresearch Funds of Hebei Geo University in 2023(QN202307)+1 种基金Opening Foundation of Hebei Key Laboratory of Strategic Critical Mineral Resources (HGUSCMR2120)National Science and Technology Major Project of China (2016ZX05006-007)
文摘The sedimentary successions around the Carboniferous-Permian boundary(CPB)in the Ordos Basin were investigated using extensive outcrop,borehole,well logging,thin section,and geochemistry data to study sedimentary and sequence stratigraphic responses to glaciation and volcanism in paleotropical transitional strata.Within the studied interval,five distinct lithofacies have been identified,including bauxite,coal,and carbonaceous shale(No.8+9 coal seams),sandstone(Qiaotou),limestone(Baode),and mudstone,which can be classified into three lithofacies associations.The most complete lithofacies associ-ation is composed of bauxite,coal,carbonaceous shale,sandstone,limestone/mudstone or their combinations from the bottom to the top,while coal and carbonaceous shale,as well as sandstone,are absent locally,resulting in the formation of the other two types of lithofacies associations.The occurrence of bauxite in-dicates shelf exposure and weathering,the occurrence of coal and carbonaceous shale indicates swampiness of the shelf,and the occurrence of sandstone reveals river rejuvenation;all of these are thought to be sedimentary responses to the transcontinental glacier expansion in Gondwana around the CPB.The presence of limestone and mudstone indicates carbonate platform and lagoon deposition,respectively,in the context of the earliest Asselian transgression caused by volcanism-induced glacier melting.The lithofacies associations record the regressive-transgressive cycles that occurred because of glaciation and volcanism near the CPB.The top surface of bauxite can be used as a sequence boundary,while the lowstand systems tract consists of the No.8+9 coal seams and the Qiaotou sandstone,and the transgressive systems tract consists of the overlying Baode limestone and laterally equivalent mudstone.The lowstand systems tract,which contains source rock and hydrocarbon reservoirs,and the overlying transgressive systems tract,which serves as cap rock,form an excellent source-reservoir-seal combination.
基金supported by the National Key Research and Development Program of China(2018YFD1000800)the National Natural Science Foundation of China(91940301)Department of Science and Technology of Hubei Province(2019AHB070).
文摘Dear Editor:RNA silencing confers immunity against most viruses and is initiated by host Dicer processing of viral doublestranded RNA into virus-derived small interfering RNA(siRNA)(Guo et al.,2019).Viruses that cause plant disease usually evolve viral suppressor of RNA silencing(VSR)to inhibit antiviral silencing(Li and Ding,2006).Some plant nucleotide-binding leucine-rich repeat proteins(NLRs)emerge as immune receptors to recognize specific virus and trigger rapid hypersensitive response(HR)at infection site to protect plants from devastating viruses(Cui et al.,2015;Deng et al.,2018).Recent studies showed that NLR immune receptors are subjected to negative regulation by plant miRNAs(Deng et al.,2018).It is well known that in some cases,mixed virus infections lead to synergism in susceptible plants due to cooperative inhibition of antiviral silencing by multiple VSRs(Pruss et al.,1997).In case of mixed virus infection in a plant with NLR targeting a single virus,heterologous VSR might play dual roles for the NLR-targeted virus.On one hand,the VSR may promote virulence by cooperative inhibition of antiviral silencing.
