Landslide susceptibility mapping is a crucial tool for analyzing geohazards in a region.Recent publications have popularized data-driven models,particularly machine learning-based methods,owing to their strong capabil...Landslide susceptibility mapping is a crucial tool for analyzing geohazards in a region.Recent publications have popularized data-driven models,particularly machine learning-based methods,owing to their strong capability in dealing with complex nonlinear problems.However,a significant proportion of these models have neglected qualitative aspects during analysis,resulting in a lack of interpretability throughout the process and causing inaccuracies in the negative sample extraction.In this study,Scoops 3D was employed as a physics-informed tool to qualitatively assess slope stability in the study area(the Hubei Province section of the Three Gorges Reservoir Area).The non-landslide samples were extracted based on the calculated factor of safety(FS).Subsequently,the random forest algorithm was employed for data-driven landslide susceptibility analysis,with the area under the receiver operating characteristic curve(AUC)serving as the model evaluation index.Compared to the benchmark model(i.e.,the standard method of utilizing the pure random forest algorithm),the proposed method’s AUC value improved by 20.1%,validating the effectiveness of the dual-driven method(physics-informed data-driven).展开更多
Traditional thiazolidinediones(TZDs),such as rosiglitazone,are peroxisome proliferator-activated receptor g(PPARg)potent agonists that can be used to treat type 2 diabetes but carry unwanted effects,including increase...Traditional thiazolidinediones(TZDs),such as rosiglitazone,are peroxisome proliferator-activated receptor g(PPARg)potent agonists that can be used to treat type 2 diabetes but carry unwanted effects,including increased risk for fracture.The present work aimed to compare the insulin-sensitizing efficacies and bone-loss side effects of CMHX008,a novel TZDs-like PPARg partial agonist,with those of rosiglitazone.A TR-FRET PPARg competitive binding assay was used to compare the binding affinity between CMHX008 and rosiglitazone.Mice were administered vehicle,CMHX008 or rosiglitazone for 16 weeks.Mesenchymal stem cells(MSCs)were used to examine differences in differentiation into osteoblasts after compounds treatment.TR-FRET showed lower affinity to PPARg by CMHX008 compared with rosiglitazone.Mice treated with CMHX008 showed insulin sensitization similar to that of mice treated with rosiglitazone,which was related to the significant inhibition of PPARg Ser273 phosphorylation and improved insulin sensitivity by facilitating the phosphorylation of insulin receptor and Akt in adipose tissues.Micro-CT and histomorphometric analyses demonstrated that the degree of trabecular bone loss after treatment with CMHX008 was weaker than that observed with rosiglitazone,as evidenced by consistent changes in BV/TV,Tb.N,Tb.Th,Tb.Sp,and the mineral apposition rate.MSCs treated with CMHX008 showed higher ALP activity and mRNA levels of bone formation markers than did cells treated with rosiglitazone in the osteoblast differentiation test.Thus,CMHX008 showed insulin-sensitizing effects similar to those of rosiglitazone with a lower risk of bone loss,suggesting that PPARg sparing eliminates the skeletal side effects of TZDs while maintaining their insulin-sensitizing properties.展开更多
Polypyrrole‐modified graphitic carbon nitride composites(PPy/g‐C3N4)are fabricated using an in‐situ polymerization method to improve the visible light photocatalytic activity of g‐C3N4.The PPy/g‐C3N4 is applied t...Polypyrrole‐modified graphitic carbon nitride composites(PPy/g‐C3N4)are fabricated using an in‐situ polymerization method to improve the visible light photocatalytic activity of g‐C3N4.The PPy/g‐C3N4 is applied to the photocatalytic degradation of methylene blue(MB)under visible light irradiation.Various characterization techniques are employed to investigate the relationship between the structural properties and photoactivities of the as‐prepared composites.Results show that the specific surface area of the PPy/g‐C3N4 composites increases upon assembly of the amorphous PPy nanoparticles on the g‐C3N4 surface.Owing to the strong conductivity,the PPy can be used as a transition channel for electrons to move onto the g‐C3N4 surface,thus inhibiting the recombination of photogenerated carriers of g‐C3N4 and improving the photocatalytic performance.The elevated light adsorption of PPy/g‐C3N4 composites is attributed to the strong absorption coefficient of PPy.The composite containing 0.75 wt%PPy exhibits a photocatalytic efficiency that is 3 times higher than that of g‐C3N4 in 2 h.Moreover,the degradation kinetics follow a pseudo‐first‐order model.A detailed photocatalytic mechanism is proposed with·OH and·O2-radicals as the main reactive species.The present work provides new insights into the mechanistic understanding of PPy in PPy/g‐C3N4 composites for environmental applications.展开更多
Nondestructive determination the internal quality of thick-skin fruits has always been a challenge.In order to investigate the prediction ability of full transmittance mode on the soluble solid content(SSC)in thick-sk...Nondestructive determination the internal quality of thick-skin fruits has always been a challenge.In order to investigate the prediction ability of full transmittance mode on the soluble solid content(SSC)in thick-skin fruits,the full transmittance spectra of citrus were collected using a visible/near infrared(Vis/NIR)portable spectrograph(550–1100 nm).Three obvious absorption peakswere found at 710,810 and 915 nmin the original spectra curve.Four spectral preprocessing methods including Smoothing,multiplicative scatter correction(MSC),standard normal variate(SNV)and first derivativewere employed to improve the quality of the original spectra.Subsequently,the effective wavelengths of SSC were selected from the original and pretreated spectra with the algorithms of successive projections algorithm(SPA),competitive adaptive reweighted sampling(CARS)and genetic algorithm(GA).Finally,the prediction models of SSC were established based on the full wavelengths and effectivewavelengths.Results showed that SPA performed the best performance on eliminating the useless information variable and optimizing the number of effective variables.The optimal predictionmodel was established based on 10 characteristic variables selected from the spectra pretreated by SNV with the algorithmof SPA,with the correlation coefficient,root mean square error,and residual predictive deviation for prediction set being 0.9165,0.5684°Brix and 2.5120,respectively.Overall,the full transmittance mode was feasible to predict the internal quality of thick-skin fruits,like citrus.Additionally,the combination of spectral preprocessing with a variable selection algorithmwas effective for developing the reliable predictionmodel.The conclusions of this study also provide an alternative method for fast and real-time detection of the internal quality of thick-skin fruits using Vis/NIR spectroscopy.展开更多
Landslide susceptibility mapping is an integral part of geological hazard analysis.Recently,the emphasis of many studies has been on data-driven models,notably those derived from machine learning,owing to their aptitu...Landslide susceptibility mapping is an integral part of geological hazard analysis.Recently,the emphasis of many studies has been on data-driven models,notably those derived from machine learning,owing to their aptitude for tackling complex non-linear problems.However,the prevailing models often disregard qualitative research,leading to limited interpretability and mistakes in extracting negative samples,i.e.inaccurate non-landslide samples.In this study,Scoops 3D(a three-dimensional slope stability analysis tool)was utilized to conduct a qualitative assessment of slope stability in the Yunyang section of the Three Gorges Reservoir area.The depth of the bedrock was predicted utilizing a Convolutional Neural Network(CNN),incorporating local boreholes and building on the insights from prior research.The Random Forest(RF)algorithm was subsequently used to execute a data-driven landslide susceptibility analysis.The proposed methodology demonstrated a notable increase of 29.25%in the evaluation metric,the area under the receiver operating characteristic curve(ROC-AUC),outperforming the prevailing benchmark model.Furthermore,the landslide susceptibility map generated by the proposed model demonstrated superior interpretability.This result not only validates the effectiveness of amalgamating mathematical and mechanistic insights for such analyses,but it also carries substantial academic and practical implications.展开更多
Increasing data indicate that cancer cell migration is regulated by extracellular matrixes and their surrounding biochemical microenvironment,playing a crucial role in pathological processes such as tumor invasion and...Increasing data indicate that cancer cell migration is regulated by extracellular matrixes and their surrounding biochemical microenvironment,playing a crucial role in pathological processes such as tumor invasion and metastasis.However,conventional two-dimensional cell culture and animal models have limitations in studying the influence of tumor microenvironment on cancer cell migration.Fortunately,the further development of microfluidic technology has provided solutions for the study of such questions.We utilize microfluidic chip to build a random collagen fiber microenvironment(RFM)model and an oriented collagen fiber microenvironment(OFM)model that resemble early stage and late stage breast cancer microenvironments,respectively.By combining cell culture,biochemical concentration gradient construction,and microscopic imaging techniques,we investigate the impact of different collagen fiber biochemical microenvironments on the migration of breast cancer MDA-MB-231-RFP cells.The results show that MDA-MB-231-RFP cells migrate further in the OFM model compared to the RFM model,with significant differences observed.Furthermore,we establish concentration gradients of the anticancer drug paclitaxel in both the RFM and OFM models and find that paclitaxel significantly inhibits the migration of MDA-MB-231-RFP cells in the RFM model,with stronger inhibition on the high concentration side compared to the low concentration side.However,the inhibitory effect of paclitaxel on the migration of MDA-MB-231-RFP cells in the OFM model is weak.These findings suggest that the oriented collagen fiber microenvironment resembling the late-stage tumor microenvironment is more favorable for cancer cell migration and that the effectiveness of anticancer drugs is diminished.The RFM and OFM models constructed in this study not only provide a platform for studying the mechanism of cancer development,but also serve as a tool for the initial measurement of drug screening.展开更多
Chinese plum(Prunus salicina Lindl.)originates from China and makes a large contribution to the global production of plums.The P.salicina‘Wushancuili'has a green coloration and high fruit quality and is economica...Chinese plum(Prunus salicina Lindl.)originates from China and makes a large contribution to the global production of plums.The P.salicina‘Wushancuili'has a green coloration and high fruit quality and is economically important in eliminating poverty and protecting ecology in the Yangtze River Three Gorges Reservoir.However,rain-induced cracking(rain-cracking,literally skin cracking caused by rain)is a limitation to‘Wushancuili'fruit production and causes severe losses.This study reported a high-quality‘Wushancuili'genome assembly consisting of a 302.17-Mb sequence with eight pseudo-chromosomes and a contig N50 of 23.59 Mb through the combination of Illumina sequencing,Pacific Biosciences HiFiⅢsequencing,and high-throughput chromosome conformation capture technology.A total of 25109 protein-coding genes are predicted and 54.17%of the genome is composed of repetitive sequences.‘Wushancuili'underwent a remarkable orthoselection during evolution.Gene identification revealed that loss-of-function in four core MYB10 genes results in the anthocyanin deficiency and absence of red color,revealing the green coloration due to the residual high chlorophyll in fruit skin.Besides,the occurrence of cracking is assumed to be closely associated with cell wall modification and frequently rain-induced pathogen enrichment through transcriptomic analysis.The loss of MYB10 genes might render fruit more susceptible to pathogen-mediated cracking by weakening the epidermal strength and reactive oxygen species(ROS)scavenging.Our findings provided fundamental knowledge regarding fruit coloration and rain-cracking and will facilitate genetic improvement and cultivation management in Chinese plums.展开更多
Type 2 diabetes mellitus(T2DM)and Alzheimer's disease(AD)share several common pathophysiological features.Rare variants of triggering receptor expressed on myeloid cells 2(TREM2)increase the risk of developing AD,...Type 2 diabetes mellitus(T2DM)and Alzheimer's disease(AD)share several common pathophysiological features.Rare variants of triggering receptor expressed on myeloid cells 2(TREM2)increase the risk of developing AD,suggesting the involvement of TREM2 and innate immunity in AD development.It is still unknown whether TREM2 is related to cognitive impairment in T2DM.Here,we investigated the effects of the hippocampal overexpression of TREM2 on cognitive in long-term high-fat diet(HFD)-fed mice.Male C57BL/6J mice were maintained on HFD for 50 weeks.TREM2 was overexpressed in the hippocampus 36 weeks after HFD feeding using adeno-associated virus vector(AAV)-mediated gene delivery.The results showed that the HFD feeding induced rapid and persistent weight gain,glucose intolerance and significant impairments in learning and memory.Compared with AAV-con,AAV-TREM2 significantly ameliorated cognitive impairment without altering body weight and glucose homeostasis in HFD mice.The overexpression of TREM2 upregulated the synaptic proteins spinophilin,PSD95 and synaptophysin,suggesting the improvement in synaptic transmission.Dendritic complexity and spine density in the CA1 region were rescued after TREM2 overexpression.Furthermore,TREM2 markedly increased the number of iba-1/Arg-1-positive microglia in the hippocampus,suppressed neuroinflammation and microglial activation.In sum,hippocampal TREM2 plays an important role in improving HFD-induced cognitive dysfunction and promoting microglial polarization towards the M2 anti-inflammatory phenotype.Our study also suggests that TREM2 might be a novel target for the intervention of obesity/diabetes-associated cognitive decline.展开更多
Myricaria laxiflora,which grows along the Yangtze River in China,holds ornamental,ecological,and medicinal value.However,its wild population is threatened and currently designated protected as a national priority.The ...Myricaria laxiflora,which grows along the Yangtze River in China,holds ornamental,ecological,and medicinal value.However,its wild population is threatened and currently designated protected as a national priority.The present research was the first to sequence and assemble M.laxiflora’s mitochondrial genome and examine its structural characteristics and phylogenetic relationships with other sequenced Caryophyllales species.The mitochondrial double-stranded closed-ring genome of M.laxiflora was found to be 389,949 bp in length,containing numerous repetitive sequences and RNA editing sites,with 34 protein encoding,21 tRNA,and 3 rRNA genes.Although there are 22 fragments in the mitochondrial genome of M.laxiflora that are homologous to its chloroplast genome,they are incomplete gene fragments.Phylogenetic analysis demonstrated evolutionary associations with related populations and was in agreement with findings on the chloroplast genome.These findings not only lay a foundation for its preservation but also offer valuable insights for evolutionary analysis and plant breeding research.展开更多
Previous studies have confirmed the time-lagged and cumulative effects of drought and anthropogenic activities on vegetation growth,but these studies focus on the time-lagged effect of drought and are poorly known how...Previous studies have confirmed the time-lagged and cumulative effects of drought and anthropogenic activities on vegetation growth,but these studies focus on the time-lagged effect of drought and are poorly known how vegetation productivity responds to anthropogenic activities.Here,based on the reconstructed Normalized Difference Vegetation Index,the Standardized Precipitation Evapotranspiration Index and land use degree comprehensive index,we diagnosed the spatiotemporal pattern of vegetation and drought,investigated time-lagged and cumulative effects of drought and anthropogenic activities over China through the month where the maximum correlation coefficient occurred.It revealed that the browning trend of 32.21%of vegetated lands was covered by overall greening,especially northwestern China.Drought intensified with a rate of 0.0014/year.in 66.41%and 54.57%of the vegetated lands had time-lagged and cumulative response to drought,with a shorter timescales of 1–4 months,indicating the higher sensitivity of vegetation growth to drought.There was a U-shaped relationship between moisture conditions and vegetation response time.49.9%of China’s vegetation showed time-lagged effects to anthropogenic activities,with a longer timescales of 6–10 years,demonstrating that anthropogenic activities triggered ecological changes but vegetation ecosystems cannot keep pace.The accumulated and time-lagged years declined with increased land use intensity.展开更多
Mountainous landscapes are particularly vulnerable and sensitive to climate change and human activities,and a clear understanding of how ecosystem services(ES)and their relationships continuously change over time,acro...Mountainous landscapes are particularly vulnerable and sensitive to climate change and human activities,and a clear understanding of how ecosystem services(ES)and their relationships continuously change over time,across space,and along altitude is therefore essential for ecosystem management.Chongqing,a typical mountainous region,was selected to assess the long-term changes in its key ES and their relationships.From 1992 to 2018,the temporal variation in water yield(WY)revealed that the maximum and minimum WYs occurred in 1998 and 2006,which coincided with El Ni?o-Southern Oscillation and severe drought events,respectively.Soil export(SE)and WY were consistent with precipitation,which reached their highest values in 1998.During this period,carbon storage(CS)and habitat quality(HQ)both decreased significantly.ES in Chongqing showed large variations in altitude.Generally,WY and SE decreased with increasing altitude,while CS and HQ increased.For spatial distribution,WY and SE showed positive trends in the west and negative trends in the east.In regard to CS and HQ,negative trends dominated the area.Persistent tradeoffs between WY and soil conservation(SC)were found at all altitude gradients.The strong synergies between CS and HQ were maintained over time.展开更多
Inland water bodies,being the most active biogeochemical cycle reactors,play a pivotal role in the global carbon cycle and CO_(2) budget.This study integrates existing observation dataset of CO_(2) flux(fCO_(2))in riv...Inland water bodies,being the most active biogeochemical cycle reactors,play a pivotal role in the global carbon cycle and CO_(2) budget.This study integrates existing observation dataset of CO_(2) flux(fCO_(2))in rivers,lakes and reservoirs in China,to elucidate their spatial-temporal patterns and key influencing factors and to reappraise the significance for regional carbon balance.It showed that,the fCO_(2) in rivers,lakes and reservoirs in China presented significant variability with large range of-379.3-4947.6,-160.1-785.0 and -74.0-1603.1 mg CO_(2)m-2h^(-1),respectively.The median of the fCO_(2) in rivers was of 228.5 mg CO_(2)m^(-2)h^(-1),observably higher than these in lakes and reservoirs(26.0 and 28.3 mg CO_(2)m^(-2)h^(-1),respectively).The fCO_(2)in rivers and reservoirs exhibited similar decreasing trend from south to north as a result of universal climate restraint,the averaged fCO_(2) in Pearl River and Yangtze River basins showed much higher than that in Northeastern rivers.While,the averaged fCO_(2) in the Mongolia-Xinjiang lake district and the Northeast lake district were higher than other lake districts,followed by the Qinghai-Xizang lake district,and the Eastern and Yungui lake district were generally low,contradicting the climatic restriction.The water primary production enhancement resulting from human activities was the main driver of spatial variation in the fCO_(2) in lakes.Meanwhile,the fCO_(2) in rivers presented seasonal pattern with higher wet season than dry season,while opposite patterns were found in lakes and reservoirs.Seasonal temperature,precipitation and water primary production were main factors.Furthermore,it showed pH was a key factor indicating the variability of the fCO_(2) levels either in rivers,lakes or in reservoirs.In lakes,the fCO_(2) is closely linked to chlorophyll a(Chl-a)and dissolved oxygen(DO),whereas,the fCO_(2) in rivers is primarily associated with organic carbon(OC)and total nitrogen(TN),highlighting the diverse controlling mechanisms of fCO_(2) in various展开更多
China’s Grain to Green Program(GTGP),which is one of the largest payments for ecosystem services(PES)in the world,has made significant ecological improvements to the environment.However,current understanding of its o...China’s Grain to Green Program(GTGP),which is one of the largest payments for ecosystem services(PES)in the world,has made significant ecological improvements to the environment.However,current understanding of its outcomes on the social-ecological system(SES)remains limited.Therefore,taking the South China Karst as an example,a SES resilience evaluation index system was constructed followed by an exploratory spatial analysis,root mean square error,and Self-Organizing Feature Map to clarify the spatiotemporal changes and relationship of SES resilience,achieve the zoning of SES resilience and provide restoration measures.The results showed an upward trend in social resilience from 2000 to 2020,especially its subsystem of social development.Regional ecological resilience was stable,owing to a slightly declined ecosystem services and increased landscape pattern.Spatially,nearly half of the counties exhibited a distribution mismatch in SES resilience.There was an obvious inverted U-shaped relationship of SES resilience,indicating a clear threshold effect,and the constraint relation-ship of SES resilience eased over time,demonstrating the effectiveness of the ecological restoration program.GTGP played a positive role in reducing regional SES trade-off,but this positive effect was limited,reflecting the limitations of overemphasizing the conversion from farmland to forest and grassland.Regional SES resilience can be divided into four clusters,which were the key optimization zone for social system,the SES resilience safety zone,the key restoration zone for SES resilience,and the key optimization zone for ecological system.Adaptive adjustments for the GTGP in these zones should be taken to achieve maximum SES benefits in the future.展开更多
Alpine grassland occupies two-thirds of the Qinghai-Tibetan Plateau (QTP). It is vital to project changes of this vulnerable ecosystem under different climate change scenarios before taking any mitigation or adaptatio...Alpine grassland occupies two-thirds of the Qinghai-Tibetan Plateau (QTP). It is vital to project changes of this vulnerable ecosystem under different climate change scenarios before taking any mitigation or adaptation measures. In this study, we used a process-based ecosystem model, driven with output from global circulation models under different Representative Concentration Pathways (RCPs), to project the carbon dynamics of alpine grassland. The results showed the following: 1) Vegetation carbon (C) on the QTP increased by 22—38 gC m^-2 during periods of 1.5 and 2 ℃ warming under different RCPs when compared to the baseline period (1981—2006), while soil C increased by 85—122 gC m^-2. 2) The increases of vegetation C and soil C at the period of 1.5 ℃ warming were about 15 gC m^-2 and 40 gC m^-2 smaller than those at the period of 2 ℃ warming, respectively;increase of C was greater for alpine meadow than for alpine steppe. 3) Precipitation, radiation, and permafrost changed significantly and showed heterogeneous spatial patterns, and caused heterogeneous response of C dynamics. For alpine meadow in regions transformed from permafrost to seasonally frozen soil with medium annual precipitation (200—400 mm), vegetation C and net primary production decreased by 18.7 gC m-2 and 3.1 gC m^-2 per year during 2 °C warming under RCP 4.5, respectively. This decrease can be attributed to the disappearing impermeable permafrost. Different from previous studies that indicated an unfavorable response of alpine grassland to climate warming, this study showed a relatively favorable response, which is mainly attributed to C 0 2 fertilization.展开更多
Maize(Zea mays L.)is one of the most important food crops in the world,and starch is the main component of its endosperm.Transcriptional regulation plays a vital role in starch biosynthesis.However,it is not well unde...Maize(Zea mays L.)is one of the most important food crops in the world,and starch is the main component of its endosperm.Transcriptional regulation plays a vital role in starch biosynthesis.However,it is not well understood in maize.We report the identification of the transcription factor ZmNAC126 and its role in regulation of starch synthesis in maize.Transcriptional expression of ZmNAC126 was higher in maize endosperm and kernels than in roots or stems.ZmNAC126 shared a similar expression pattern with starch synthesis genes during seed development,and its expression pattern was also consistent with the accumulation of starch.ZmNAC126 is a typical transcription factor with a transactivation domain between positions 201 and 227 of the amino acid sequence,is located in the nucleus,and binds to CACG repeats in vitro.Yeast one-hybrid assay revealed that ZmNAC126 bound the promoters of ZmGBSSI,ZmSSIIa,ZmSSIV,ZmISA1,and ZmISA2.Transient overexpression of ZmNAC126 in maize endosperm increased the activities of promoters pZmSh2,pZmBt2,pZmGBSSI,pZmSSIIIa,and pZmBT1 but inhibited the activities of pZmISA1 and pZmISA2.ZmNAC126 thus acts in starch synthesis by transcriptionally regulating targeted starch synthesis-related genes in maize kernels.展开更多
Landslides are one of the geological disasters with wide distribution,high impact and serious damage around the world.Landslide risk assessment can help us know the risk of landslides occurring,which is an effective w...Landslides are one of the geological disasters with wide distribution,high impact and serious damage around the world.Landslide risk assessment can help us know the risk of landslides occurring,which is an effective way to prevent landslide disasters in advance.In recent decades,artificial intelligence(AI)has developed rapidly and has been used in a wide range of applications,especially for natural hazards.Based on the published literatures,this paper presents a detailed review of AI applications in landslide risk assessment.Three key areas where the application of AI is prominent are identified,including landslide detection,landslide susceptibility assessment,and prediction of landslide displacement.Machine learning(ML)containing deep learning(DL)has emerged as the primary technology which has been considered successfully due to its ability to quantify complex nonlinear relationships of soil structures and landslide predisposing factors.Among the algorithms,convolutional neural networks(CNNs)and recurrent neural networks(RNNs)are two models that are most widely used with satisfactory results in landslide risk assessment.The generalization ability,sampling training strategies,and hyperparameters optimization of these models are crucial and should be carefully considered.The challenges and opportunities of AI applications are also fully discussed to provide suggestions for future research in landslide risk assessment.展开更多
Soil texture is an indicator of soil physical structure which delivers many ecological functions of soils such as thermal regime, plant growth, and soil quality. However, traditional methods for soil texture measureme...Soil texture is an indicator of soil physical structure which delivers many ecological functions of soils such as thermal regime, plant growth, and soil quality. However, traditional methods for soil texture measurement are time-consuming and labor-intensive. This study attempts to explore an indirect method for rapid estimating the texture of three subgroups of purple soils (i.e. calcareous, neutral, and acidic). 190 topsoil (0 - 10 cm) samples were collected from sloping croplands in Tongnan and Beibei Districts of Chongqing Municipality in China. Vis-NIR spectrum was measured and processed, and stepwise multiple linear regression (SMLR), partial least squares regression (PLSR), and back propagation neural network (BPNN) models were constructed to inform the soil texture. The clay fractions ranged from 4.40% to 27.12% while sand fractions ranged from 0.34% to 36.57%, hereby soil samples encompass three textural classes (i.e. silt, silt loam, and silty clay loam). For the original spectrum, the texture of calcareous and neutral purple soils was not significantly correlated with spectral reflectance and linear models (SMLR and PLSR) exhibited low prediction accuracy. The correlation coefficients and the goodness-of-fits between soil texture and the transformed spectra of all soil groups increased by continuum-removal (CR), first-order differential (R'), and second-order differential (R") transformations. Among them, the R" had the best performance in terms of improving the correlation coefficients and the goodness-of-fits. For the calcareous purple soil, the SMLR exceeds PLSR and BPNN with a higher coefficient of determination (R<sup>2</sup>) and the ratio of performance to inter-quartile distance (RPIQ) values and lower root mean square error of validation (RMSEV), but for the neutral and acidic purple soils, the PLSR model has a better prediction accuracy. In summary, the linear methods (SMLR and PLSR) are more reliable in estimating the texture of the three purple soil groups when using Vis-NIR spectroscopy in展开更多
Vegetation canopies intercept and redistribute rainfall into throughfall and stemflow,which transfer substantial amounts of elements into the soil,influencing soil microbial community,plant survival,and plant communit...Vegetation canopies intercept and redistribute rainfall into throughfall and stemflow,which transfer substantial amounts of elements into the soil,influencing soil microbial community,plant survival,and plant community succession.Despite advancements in ecohydrological research,the implication of nutrient enrichment resulting from this redistribution of rainfall by canopies remains largely unexplored.To address this gap,we conducted a systematic review of 1020 papers published between 2000 and 2022,gathering data on nutrient concentration and enrichment for critical ions(including K^(+),Na^(+),Ca^(2+),Mg^(2+),NH_(4)^(+),Cl^(-),NO_(3)^(-)and SO_(4)^(2-))from the Web of Science and Chinese Knowledge Infrastructure databases.We aimed to synthesize the mechanisms,quantify the enrichments,and identify global patterns of nutrient enrichment in stemflow and throughfall across climate zones,and vegetation types and ecosystems.The results of this study indicate that stemflow exhibits,on average,2.1times greater ion concentration(6.13 mg L^(-1))compared to throughfall.In particular,among the investigated ions,SO_(4)^(2-)(12.45and 6.32 mg L^(-1))for stemflow and throughfall,respectively,and Cl^(-)(9.21 and 4.81 mg L^(-1))exhibit the highest concentrations in both rainfall redistribution components,while K^(+)(13.7 and 5.8)and Mg^(2+)(5.6 and 2.8)have the highest enrichment factors.Across climate zones,throughfall and stemflow show the lowest ion concentrations but the highest enrichment factors in extremely humid regions.Along the temperature gradient,ion concentrations are the highest in cold climates with no clear patterns observed for enrichment factors with increasing temperature.In addition,shrubs,conifers,mixed forests,and artificial ecosystems demonstrate enrichment factors 1.1 to 3.0 times greater than those of trees,broad-leaved plants,pure forests,and natural ecosystems.These findings emphasize the need for increased attentions to artificial ecosystems,such as urban and agricultural ecosystems,which often received展开更多
To investigate the dynamical load sharing behaviors of multi-floating components in the heavy load planetary gear system,a multi-floating planetary gear system that includes a floating central component and a quasi-fl...To investigate the dynamical load sharing behaviors of multi-floating components in the heavy load planetary gear system,a multi-floating planetary gear system that includes a floating central component and a quasi-floating planet flexible supporting pin is employed.Then a 21 degree of freedom lumped parameters dynamical model of this system is presented to study the dynamical load sharing behaviors.Some influencing factors,such as supporting stiffness,positions error of sun or carrier,and external input load are analyzed on the dynamical load sharing of the planetary gear system with multi-floating components.The results demonstrate that the load sharing condition of the system is best when both the sun gear and planet gears are multi-floating at the same time.When the planet gear position errors remain constant,reducing the flexible pin stiffness of planet gear or increasing external input load can effectively improve the load sharing.These conclusions are verified by the relevant experiments.展开更多
The landscape index is a quantitative index which reflects characteristics of structure composition and spatial pattern in landscape studies,it is,therefore,expected to describe the spatial pattern of scientific resea...The landscape index is a quantitative index which reflects characteristics of structure composition and spatial pattern in landscape studies,it is,therefore,expected to describe the spatial pattern of scientific research in bibliometric analysis.In this study,a novel attempt to regard scientific research as a kind of‘landscape’was made,and landscape indices were improved for bibliometric analysis to measure the spatial pattern of scientific research.For illustrating the feasibility of our method,global geoscience research from 1994 to 2018 was presented as a case.Moreover,spatiotemporal migration of landscape centroids was visualized.The results indicated that global geoscience publications increased steadily and articles were highly concentrated at the country level.The top 10 countries published 69.93%of total articles and 84.68%of geoscience articles were from top 20 productive countries.The spatial migration of centroids was mainly reflected in the longitude because of significant increasing of articles in eastern countries,especially in China with the growth rate of 747.14%.At the patch scale,the change trend of improved landscape indices verified the spatiotemporal changes of global distribution of geoscience articles.At the landscape scale,the strengthening of global international collaboration is the main driving forces of spatial heterogeneity of global geoscience research.This study is expected to help readers to understand global trends of geoscience research in the past 25 years,and to promote the development of bibliometric analysis towards the directions of spatialization and visualization.展开更多
基金funded by the National Key R&D Program of China(Project No.2019YFC1509605)High-end Foreign Expert Introduction program(No.G20200022005 and DL2021165001L)Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.HZ2021001)。
文摘Landslide susceptibility mapping is a crucial tool for analyzing geohazards in a region.Recent publications have popularized data-driven models,particularly machine learning-based methods,owing to their strong capability in dealing with complex nonlinear problems.However,a significant proportion of these models have neglected qualitative aspects during analysis,resulting in a lack of interpretability throughout the process and causing inaccuracies in the negative sample extraction.In this study,Scoops 3D was employed as a physics-informed tool to qualitatively assess slope stability in the study area(the Hubei Province section of the Three Gorges Reservoir Area).The non-landslide samples were extracted based on the calculated factor of safety(FS).Subsequently,the random forest algorithm was employed for data-driven landslide susceptibility analysis,with the area under the receiver operating characteristic curve(AUC)serving as the model evaluation index.Compared to the benchmark model(i.e.,the standard method of utilizing the pure random forest algorithm),the proposed method’s AUC value improved by 20.1%,validating the effectiveness of the dual-driven method(physics-informed data-driven).
基金supported by the National Natural Science Foundation of China(81270947 and 81570763,to XX)the National Program on Key Basic Research Project of China(973 Program,2012CB517505,to XX)+1 种基金the Fundamental Science and Advanced Technology Research of Chongqing(Major Project,CSTC2015jcyjB0146)Chongqing Graduate Student Research Innovation Fund(CYB15095,to HY)。
文摘Traditional thiazolidinediones(TZDs),such as rosiglitazone,are peroxisome proliferator-activated receptor g(PPARg)potent agonists that can be used to treat type 2 diabetes but carry unwanted effects,including increased risk for fracture.The present work aimed to compare the insulin-sensitizing efficacies and bone-loss side effects of CMHX008,a novel TZDs-like PPARg partial agonist,with those of rosiglitazone.A TR-FRET PPARg competitive binding assay was used to compare the binding affinity between CMHX008 and rosiglitazone.Mice were administered vehicle,CMHX008 or rosiglitazone for 16 weeks.Mesenchymal stem cells(MSCs)were used to examine differences in differentiation into osteoblasts after compounds treatment.TR-FRET showed lower affinity to PPARg by CMHX008 compared with rosiglitazone.Mice treated with CMHX008 showed insulin sensitization similar to that of mice treated with rosiglitazone,which was related to the significant inhibition of PPARg Ser273 phosphorylation and improved insulin sensitivity by facilitating the phosphorylation of insulin receptor and Akt in adipose tissues.Micro-CT and histomorphometric analyses demonstrated that the degree of trabecular bone loss after treatment with CMHX008 was weaker than that observed with rosiglitazone,as evidenced by consistent changes in BV/TV,Tb.N,Tb.Th,Tb.Sp,and the mineral apposition rate.MSCs treated with CMHX008 showed higher ALP activity and mRNA levels of bone formation markers than did cells treated with rosiglitazone in the osteoblast differentiation test.Thus,CMHX008 showed insulin-sensitizing effects similar to those of rosiglitazone with a lower risk of bone loss,suggesting that PPARg sparing eliminates the skeletal side effects of TZDs while maintaining their insulin-sensitizing properties.
文摘Polypyrrole‐modified graphitic carbon nitride composites(PPy/g‐C3N4)are fabricated using an in‐situ polymerization method to improve the visible light photocatalytic activity of g‐C3N4.The PPy/g‐C3N4 is applied to the photocatalytic degradation of methylene blue(MB)under visible light irradiation.Various characterization techniques are employed to investigate the relationship between the structural properties and photoactivities of the as‐prepared composites.Results show that the specific surface area of the PPy/g‐C3N4 composites increases upon assembly of the amorphous PPy nanoparticles on the g‐C3N4 surface.Owing to the strong conductivity,the PPy can be used as a transition channel for electrons to move onto the g‐C3N4 surface,thus inhibiting the recombination of photogenerated carriers of g‐C3N4 and improving the photocatalytic performance.The elevated light adsorption of PPy/g‐C3N4 composites is attributed to the strong absorption coefficient of PPy.The composite containing 0.75 wt%PPy exhibits a photocatalytic efficiency that is 3 times higher than that of g‐C3N4 in 2 h.Moreover,the degradation kinetics follow a pseudo‐first‐order model.A detailed photocatalytic mechanism is proposed with·OH and·O2-radicals as the main reactive species.The present work provides new insights into the mechanistic understanding of PPy in PPy/g‐C3N4 composites for environmental applications.
基金This study was supported by National Key Research and Development Program(2016YFD0200104)Beijing Talents Foundation(2018000021223ZK06)National Natural Science Foundation of China(Grant No.31671927).
文摘Nondestructive determination the internal quality of thick-skin fruits has always been a challenge.In order to investigate the prediction ability of full transmittance mode on the soluble solid content(SSC)in thick-skin fruits,the full transmittance spectra of citrus were collected using a visible/near infrared(Vis/NIR)portable spectrograph(550–1100 nm).Three obvious absorption peakswere found at 710,810 and 915 nmin the original spectra curve.Four spectral preprocessing methods including Smoothing,multiplicative scatter correction(MSC),standard normal variate(SNV)and first derivativewere employed to improve the quality of the original spectra.Subsequently,the effective wavelengths of SSC were selected from the original and pretreated spectra with the algorithms of successive projections algorithm(SPA),competitive adaptive reweighted sampling(CARS)and genetic algorithm(GA).Finally,the prediction models of SSC were established based on the full wavelengths and effectivewavelengths.Results showed that SPA performed the best performance on eliminating the useless information variable and optimizing the number of effective variables.The optimal predictionmodel was established based on 10 characteristic variables selected from the spectra pretreated by SNV with the algorithmof SPA,with the correlation coefficient,root mean square error,and residual predictive deviation for prediction set being 0.9165,0.5684°Brix and 2.5120,respectively.Overall,the full transmittance mode was feasible to predict the internal quality of thick-skin fruits,like citrus.Additionally,the combination of spectral preprocessing with a variable selection algorithmwas effective for developing the reliable predictionmodel.The conclusions of this study also provide an alternative method for fast and real-time detection of the internal quality of thick-skin fruits using Vis/NIR spectroscopy.
基金funded by the Sichuan Transportation Science and Technology Project(Grant No.2018-ZL-01)High-end Foreign Expert Introduction program(Grant No.G2022165004L)Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.HZ2021001).
文摘Landslide susceptibility mapping is an integral part of geological hazard analysis.Recently,the emphasis of many studies has been on data-driven models,notably those derived from machine learning,owing to their aptitude for tackling complex non-linear problems.However,the prevailing models often disregard qualitative research,leading to limited interpretability and mistakes in extracting negative samples,i.e.inaccurate non-landslide samples.In this study,Scoops 3D(a three-dimensional slope stability analysis tool)was utilized to conduct a qualitative assessment of slope stability in the Yunyang section of the Three Gorges Reservoir area.The depth of the bedrock was predicted utilizing a Convolutional Neural Network(CNN),incorporating local boreholes and building on the insights from prior research.The Random Forest(RF)algorithm was subsequently used to execute a data-driven landslide susceptibility analysis.The proposed methodology demonstrated a notable increase of 29.25%in the evaluation metric,the area under the receiver operating characteristic curve(ROC-AUC),outperforming the prevailing benchmark model.Furthermore,the landslide susceptibility map generated by the proposed model demonstrated superior interpretability.This result not only validates the effectiveness of amalgamating mathematical and mechanistic insights for such analyses,but it also carries substantial academic and practical implications.
基金support from the National Natural Science Foundation of China(Grant Nos.11974066,12174041,12104134,T2350007,and 12347178)the Fundamental and Advanced Research Program of Chongqing(Grant No.cstc2019jcyj-msxm X0477)+3 种基金the Natural Science Foundation of Chongqing(Grant No.CSTB2022NSCQMSX1260)the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202301333)the Scientific Research Fund of Chongqing University of Arts and Sciences(Grant Nos.R2023HH03 and P2022HH05)College Students’Innovation and Entrepreneurship Training Program of Chongqing Municipal(Grant No.S202310642002)。
文摘Increasing data indicate that cancer cell migration is regulated by extracellular matrixes and their surrounding biochemical microenvironment,playing a crucial role in pathological processes such as tumor invasion and metastasis.However,conventional two-dimensional cell culture and animal models have limitations in studying the influence of tumor microenvironment on cancer cell migration.Fortunately,the further development of microfluidic technology has provided solutions for the study of such questions.We utilize microfluidic chip to build a random collagen fiber microenvironment(RFM)model and an oriented collagen fiber microenvironment(OFM)model that resemble early stage and late stage breast cancer microenvironments,respectively.By combining cell culture,biochemical concentration gradient construction,and microscopic imaging techniques,we investigate the impact of different collagen fiber biochemical microenvironments on the migration of breast cancer MDA-MB-231-RFP cells.The results show that MDA-MB-231-RFP cells migrate further in the OFM model compared to the RFM model,with significant differences observed.Furthermore,we establish concentration gradients of the anticancer drug paclitaxel in both the RFM and OFM models and find that paclitaxel significantly inhibits the migration of MDA-MB-231-RFP cells in the RFM model,with stronger inhibition on the high concentration side compared to the low concentration side.However,the inhibitory effect of paclitaxel on the migration of MDA-MB-231-RFP cells in the OFM model is weak.These findings suggest that the oriented collagen fiber microenvironment resembling the late-stage tumor microenvironment is more favorable for cancer cell migration and that the effectiveness of anticancer drugs is diminished.The RFM and OFM models constructed in this study not only provide a platform for studying the mechanism of cancer development,but also serve as a tool for the initial measurement of drug screening.
基金financially supported by the Construction Program for Chongqing's Distinctive“Wushancuili”Industry(Grant No.4322200370)Strategic Cooperation Project of Chongqing Municipality and Chinese Academy of Agricultural Sciences(Grant No.4322300181)Fundamental Research Funds for Central Universities-Talent induction project(Grant Nos.SWU-KR22001,SWU-KQ22070)。
文摘Chinese plum(Prunus salicina Lindl.)originates from China and makes a large contribution to the global production of plums.The P.salicina‘Wushancuili'has a green coloration and high fruit quality and is economically important in eliminating poverty and protecting ecology in the Yangtze River Three Gorges Reservoir.However,rain-induced cracking(rain-cracking,literally skin cracking caused by rain)is a limitation to‘Wushancuili'fruit production and causes severe losses.This study reported a high-quality‘Wushancuili'genome assembly consisting of a 302.17-Mb sequence with eight pseudo-chromosomes and a contig N50 of 23.59 Mb through the combination of Illumina sequencing,Pacific Biosciences HiFiⅢsequencing,and high-throughput chromosome conformation capture technology.A total of 25109 protein-coding genes are predicted and 54.17%of the genome is composed of repetitive sequences.‘Wushancuili'underwent a remarkable orthoselection during evolution.Gene identification revealed that loss-of-function in four core MYB10 genes results in the anthocyanin deficiency and absence of red color,revealing the green coloration due to the residual high chlorophyll in fruit skin.Besides,the occurrence of cracking is assumed to be closely associated with cell wall modification and frequently rain-induced pathogen enrichment through transcriptomic analysis.The loss of MYB10 genes might render fruit more susceptible to pathogen-mediated cracking by weakening the epidermal strength and reactive oxygen species(ROS)scavenging.Our findings provided fundamental knowledge regarding fruit coloration and rain-cracking and will facilitate genetic improvement and cultivation management in Chinese plums.
基金This work was supported by the National Natural Science Foundation of China(No.81871222,81570763 and 81270947,to XX)the Fundamental Science and Advanced Technology Research of Chongqing(Major Project,No.CSTC2015jcyjB0146)the National Program on Key Basic Research Project(973 Program)of China(973 Program,No.2012CB517505,to XX).
文摘Type 2 diabetes mellitus(T2DM)and Alzheimer's disease(AD)share several common pathophysiological features.Rare variants of triggering receptor expressed on myeloid cells 2(TREM2)increase the risk of developing AD,suggesting the involvement of TREM2 and innate immunity in AD development.It is still unknown whether TREM2 is related to cognitive impairment in T2DM.Here,we investigated the effects of the hippocampal overexpression of TREM2 on cognitive in long-term high-fat diet(HFD)-fed mice.Male C57BL/6J mice were maintained on HFD for 50 weeks.TREM2 was overexpressed in the hippocampus 36 weeks after HFD feeding using adeno-associated virus vector(AAV)-mediated gene delivery.The results showed that the HFD feeding induced rapid and persistent weight gain,glucose intolerance and significant impairments in learning and memory.Compared with AAV-con,AAV-TREM2 significantly ameliorated cognitive impairment without altering body weight and glucose homeostasis in HFD mice.The overexpression of TREM2 upregulated the synaptic proteins spinophilin,PSD95 and synaptophysin,suggesting the improvement in synaptic transmission.Dendritic complexity and spine density in the CA1 region were rescued after TREM2 overexpression.Furthermore,TREM2 markedly increased the number of iba-1/Arg-1-positive microglia in the hippocampus,suppressed neuroinflammation and microglial activation.In sum,hippocampal TREM2 plays an important role in improving HFD-induced cognitive dysfunction and promoting microglial polarization towards the M2 anti-inflammatory phenotype.Our study also suggests that TREM2 might be a novel target for the intervention of obesity/diabetes-associated cognitive decline.
基金funded by the Youth Project of the Science and Technology Research Program of the Chongqing Education Commission(No.KJQN202303329)supported by the Scientific Research Project of Promoting Forestry Development through Science and Technology in Chongqing(No.YLKYQN2024-3).
文摘Myricaria laxiflora,which grows along the Yangtze River in China,holds ornamental,ecological,and medicinal value.However,its wild population is threatened and currently designated protected as a national priority.The present research was the first to sequence and assemble M.laxiflora’s mitochondrial genome and examine its structural characteristics and phylogenetic relationships with other sequenced Caryophyllales species.The mitochondrial double-stranded closed-ring genome of M.laxiflora was found to be 389,949 bp in length,containing numerous repetitive sequences and RNA editing sites,with 34 protein encoding,21 tRNA,and 3 rRNA genes.Although there are 22 fragments in the mitochondrial genome of M.laxiflora that are homologous to its chloroplast genome,they are incomplete gene fragments.Phylogenetic analysis demonstrated evolutionary associations with related populations and was in agreement with findings on the chloroplast genome.These findings not only lay a foundation for its preservation but also offer valuable insights for evolutionary analysis and plant breeding research.
基金supported by the National Natural Science Foundation of China program(No.42001090)the Special Fund Projects of Central Government Guiding Local Science and Technology Development(No.Guike ZY20198012).
文摘Previous studies have confirmed the time-lagged and cumulative effects of drought and anthropogenic activities on vegetation growth,but these studies focus on the time-lagged effect of drought and are poorly known how vegetation productivity responds to anthropogenic activities.Here,based on the reconstructed Normalized Difference Vegetation Index,the Standardized Precipitation Evapotranspiration Index and land use degree comprehensive index,we diagnosed the spatiotemporal pattern of vegetation and drought,investigated time-lagged and cumulative effects of drought and anthropogenic activities over China through the month where the maximum correlation coefficient occurred.It revealed that the browning trend of 32.21%of vegetated lands was covered by overall greening,especially northwestern China.Drought intensified with a rate of 0.0014/year.in 66.41%and 54.57%of the vegetated lands had time-lagged and cumulative response to drought,with a shorter timescales of 1–4 months,indicating the higher sensitivity of vegetation growth to drought.There was a U-shaped relationship between moisture conditions and vegetation response time.49.9%of China’s vegetation showed time-lagged effects to anthropogenic activities,with a longer timescales of 6–10 years,demonstrating that anthropogenic activities triggered ecological changes but vegetation ecosystems cannot keep pace.The accumulated and time-lagged years declined with increased land use intensity.
基金National Natural Science Foundation of China,No.41701611,No.41830648General Program of Social Science and Planning of Chongqing,No.2020YBZX15Fundamental Research Funds for the Central Universities,No.XDJK2019C090。
文摘Mountainous landscapes are particularly vulnerable and sensitive to climate change and human activities,and a clear understanding of how ecosystem services(ES)and their relationships continuously change over time,across space,and along altitude is therefore essential for ecosystem management.Chongqing,a typical mountainous region,was selected to assess the long-term changes in its key ES and their relationships.From 1992 to 2018,the temporal variation in water yield(WY)revealed that the maximum and minimum WYs occurred in 1998 and 2006,which coincided with El Ni?o-Southern Oscillation and severe drought events,respectively.Soil export(SE)and WY were consistent with precipitation,which reached their highest values in 1998.During this period,carbon storage(CS)and habitat quality(HQ)both decreased significantly.ES in Chongqing showed large variations in altitude.Generally,WY and SE decreased with increasing altitude,while CS and HQ increased.For spatial distribution,WY and SE showed positive trends in the west and negative trends in the east.In regard to CS and HQ,negative trends dominated the area.Persistent tradeoffs between WY and soil conservation(SC)were found at all altitude gradients.The strong synergies between CS and HQ were maintained over time.
基金supported by the National Natural Science Foundation of China(Grant Nos.32371680,41807321)the Natural Science Foundation of Chongqing(Grant No.2022NSCQMSX2598)the Science and Technology Project of Chongqing Education Commission(Grant Nos.KJQN202200536,KJZD-K202000502)。
文摘Inland water bodies,being the most active biogeochemical cycle reactors,play a pivotal role in the global carbon cycle and CO_(2) budget.This study integrates existing observation dataset of CO_(2) flux(fCO_(2))in rivers,lakes and reservoirs in China,to elucidate their spatial-temporal patterns and key influencing factors and to reappraise the significance for regional carbon balance.It showed that,the fCO_(2) in rivers,lakes and reservoirs in China presented significant variability with large range of-379.3-4947.6,-160.1-785.0 and -74.0-1603.1 mg CO_(2)m-2h^(-1),respectively.The median of the fCO_(2) in rivers was of 228.5 mg CO_(2)m^(-2)h^(-1),observably higher than these in lakes and reservoirs(26.0 and 28.3 mg CO_(2)m^(-2)h^(-1),respectively).The fCO_(2)in rivers and reservoirs exhibited similar decreasing trend from south to north as a result of universal climate restraint,the averaged fCO_(2) in Pearl River and Yangtze River basins showed much higher than that in Northeastern rivers.While,the averaged fCO_(2) in the Mongolia-Xinjiang lake district and the Northeast lake district were higher than other lake districts,followed by the Qinghai-Xizang lake district,and the Eastern and Yungui lake district were generally low,contradicting the climatic restriction.The water primary production enhancement resulting from human activities was the main driver of spatial variation in the fCO_(2) in lakes.Meanwhile,the fCO_(2) in rivers presented seasonal pattern with higher wet season than dry season,while opposite patterns were found in lakes and reservoirs.Seasonal temperature,precipitation and water primary production were main factors.Furthermore,it showed pH was a key factor indicating the variability of the fCO_(2) levels either in rivers,lakes or in reservoirs.In lakes,the fCO_(2) is closely linked to chlorophyll a(Chl-a)and dissolved oxygen(DO),whereas,the fCO_(2) in rivers is primarily associated with organic carbon(OC)and total nitrogen(TN),highlighting the diverse controlling mechanisms of fCO_(2) in various
基金the National Key Research and Development Program of China(Grant No.2022YFF1300701)National Natural Science Foundation of China(Grant No.42001090).
文摘China’s Grain to Green Program(GTGP),which is one of the largest payments for ecosystem services(PES)in the world,has made significant ecological improvements to the environment.However,current understanding of its outcomes on the social-ecological system(SES)remains limited.Therefore,taking the South China Karst as an example,a SES resilience evaluation index system was constructed followed by an exploratory spatial analysis,root mean square error,and Self-Organizing Feature Map to clarify the spatiotemporal changes and relationship of SES resilience,achieve the zoning of SES resilience and provide restoration measures.The results showed an upward trend in social resilience from 2000 to 2020,especially its subsystem of social development.Regional ecological resilience was stable,owing to a slightly declined ecosystem services and increased landscape pattern.Spatially,nearly half of the counties exhibited a distribution mismatch in SES resilience.There was an obvious inverted U-shaped relationship of SES resilience,indicating a clear threshold effect,and the constraint relation-ship of SES resilience eased over time,demonstrating the effectiveness of the ecological restoration program.GTGP played a positive role in reducing regional SES trade-off,but this positive effect was limited,reflecting the limitations of overemphasizing the conversion from farmland to forest and grassland.Regional SES resilience can be divided into four clusters,which were the key optimization zone for social system,the SES resilience safety zone,the key restoration zone for SES resilience,and the key optimization zone for ecological system.Adaptive adjustments for the GTGP in these zones should be taken to achieve maximum SES benefits in the future.
基金This study was jointly supported through grants provided as part of the Na tional Natural Science Foundation of China (41690142, 41730751)the State Key Laboratory of Cryospheric Science (SKLCS-ZZ-2-2018).
文摘Alpine grassland occupies two-thirds of the Qinghai-Tibetan Plateau (QTP). It is vital to project changes of this vulnerable ecosystem under different climate change scenarios before taking any mitigation or adaptation measures. In this study, we used a process-based ecosystem model, driven with output from global circulation models under different Representative Concentration Pathways (RCPs), to project the carbon dynamics of alpine grassland. The results showed the following: 1) Vegetation carbon (C) on the QTP increased by 22—38 gC m^-2 during periods of 1.5 and 2 ℃ warming under different RCPs when compared to the baseline period (1981—2006), while soil C increased by 85—122 gC m^-2. 2) The increases of vegetation C and soil C at the period of 1.5 ℃ warming were about 15 gC m^-2 and 40 gC m^-2 smaller than those at the period of 2 ℃ warming, respectively;increase of C was greater for alpine meadow than for alpine steppe. 3) Precipitation, radiation, and permafrost changed significantly and showed heterogeneous spatial patterns, and caused heterogeneous response of C dynamics. For alpine meadow in regions transformed from permafrost to seasonally frozen soil with medium annual precipitation (200—400 mm), vegetation C and net primary production decreased by 18.7 gC m-2 and 3.1 gC m^-2 per year during 2 °C warming under RCP 4.5, respectively. This decrease can be attributed to the disappearing impermeable permafrost. Different from previous studies that indicated an unfavorable response of alpine grassland to climate warming, this study showed a relatively favorable response, which is mainly attributed to C 0 2 fertilization.
基金supported by the National Natural Science Foundation of China(31571757)the National Key Basic Research Program of China(2014CB138202)。
文摘Maize(Zea mays L.)is one of the most important food crops in the world,and starch is the main component of its endosperm.Transcriptional regulation plays a vital role in starch biosynthesis.However,it is not well understood in maize.We report the identification of the transcription factor ZmNAC126 and its role in regulation of starch synthesis in maize.Transcriptional expression of ZmNAC126 was higher in maize endosperm and kernels than in roots or stems.ZmNAC126 shared a similar expression pattern with starch synthesis genes during seed development,and its expression pattern was also consistent with the accumulation of starch.ZmNAC126 is a typical transcription factor with a transactivation domain between positions 201 and 227 of the amino acid sequence,is located in the nucleus,and binds to CACG repeats in vitro.Yeast one-hybrid assay revealed that ZmNAC126 bound the promoters of ZmGBSSI,ZmSSIIa,ZmSSIV,ZmISA1,and ZmISA2.Transient overexpression of ZmNAC126 in maize endosperm increased the activities of promoters pZmSh2,pZmBt2,pZmGBSSI,pZmSSIIIa,and pZmBT1 but inhibited the activities of pZmISA1 and pZmISA2.ZmNAC126 thus acts in starch synthesis by transcriptionally regulating targeted starch synthesis-related genes in maize kernels.
基金supported by the National Natural Science Foundation of China(U2240221 and 52379105)the Sichuan Youth Science and Technology Innovation Research Team Project(2020JDTD0006)。
文摘Landslides are one of the geological disasters with wide distribution,high impact and serious damage around the world.Landslide risk assessment can help us know the risk of landslides occurring,which is an effective way to prevent landslide disasters in advance.In recent decades,artificial intelligence(AI)has developed rapidly and has been used in a wide range of applications,especially for natural hazards.Based on the published literatures,this paper presents a detailed review of AI applications in landslide risk assessment.Three key areas where the application of AI is prominent are identified,including landslide detection,landslide susceptibility assessment,and prediction of landslide displacement.Machine learning(ML)containing deep learning(DL)has emerged as the primary technology which has been considered successfully due to its ability to quantify complex nonlinear relationships of soil structures and landslide predisposing factors.Among the algorithms,convolutional neural networks(CNNs)and recurrent neural networks(RNNs)are two models that are most widely used with satisfactory results in landslide risk assessment.The generalization ability,sampling training strategies,and hyperparameters optimization of these models are crucial and should be carefully considered.The challenges and opportunities of AI applications are also fully discussed to provide suggestions for future research in landslide risk assessment.
文摘Soil texture is an indicator of soil physical structure which delivers many ecological functions of soils such as thermal regime, plant growth, and soil quality. However, traditional methods for soil texture measurement are time-consuming and labor-intensive. This study attempts to explore an indirect method for rapid estimating the texture of three subgroups of purple soils (i.e. calcareous, neutral, and acidic). 190 topsoil (0 - 10 cm) samples were collected from sloping croplands in Tongnan and Beibei Districts of Chongqing Municipality in China. Vis-NIR spectrum was measured and processed, and stepwise multiple linear regression (SMLR), partial least squares regression (PLSR), and back propagation neural network (BPNN) models were constructed to inform the soil texture. The clay fractions ranged from 4.40% to 27.12% while sand fractions ranged from 0.34% to 36.57%, hereby soil samples encompass three textural classes (i.e. silt, silt loam, and silty clay loam). For the original spectrum, the texture of calcareous and neutral purple soils was not significantly correlated with spectral reflectance and linear models (SMLR and PLSR) exhibited low prediction accuracy. The correlation coefficients and the goodness-of-fits between soil texture and the transformed spectra of all soil groups increased by continuum-removal (CR), first-order differential (R'), and second-order differential (R") transformations. Among them, the R" had the best performance in terms of improving the correlation coefficients and the goodness-of-fits. For the calcareous purple soil, the SMLR exceeds PLSR and BPNN with a higher coefficient of determination (R<sup>2</sup>) and the ratio of performance to inter-quartile distance (RPIQ) values and lower root mean square error of validation (RMSEV), but for the neutral and acidic purple soils, the PLSR model has a better prediction accuracy. In summary, the linear methods (SMLR and PLSR) are more reliable in estimating the texture of the three purple soil groups when using Vis-NIR spectroscopy in
基金supported by the National Natural Science Foundation of China(Grant No.41901038)the Start-up Research Fund of Southwest University(Grant No.SWU-KR24003)+2 种基金the Open Foundation of the State Key Laboratory of Urban and Regional Ecology of China(Grant No.SKLURE2022-2-4)the Science Fund for Distinguished Young Scholars of Chongqing(Grant No.cstc2021jcyjjqX0026)the Special Fund for Youth Team of Southwest University(Grant No.SWUXDJH202306)。
文摘Vegetation canopies intercept and redistribute rainfall into throughfall and stemflow,which transfer substantial amounts of elements into the soil,influencing soil microbial community,plant survival,and plant community succession.Despite advancements in ecohydrological research,the implication of nutrient enrichment resulting from this redistribution of rainfall by canopies remains largely unexplored.To address this gap,we conducted a systematic review of 1020 papers published between 2000 and 2022,gathering data on nutrient concentration and enrichment for critical ions(including K^(+),Na^(+),Ca^(2+),Mg^(2+),NH_(4)^(+),Cl^(-),NO_(3)^(-)and SO_(4)^(2-))from the Web of Science and Chinese Knowledge Infrastructure databases.We aimed to synthesize the mechanisms,quantify the enrichments,and identify global patterns of nutrient enrichment in stemflow and throughfall across climate zones,and vegetation types and ecosystems.The results of this study indicate that stemflow exhibits,on average,2.1times greater ion concentration(6.13 mg L^(-1))compared to throughfall.In particular,among the investigated ions,SO_(4)^(2-)(12.45and 6.32 mg L^(-1))for stemflow and throughfall,respectively,and Cl^(-)(9.21 and 4.81 mg L^(-1))exhibit the highest concentrations in both rainfall redistribution components,while K^(+)(13.7 and 5.8)and Mg^(2+)(5.6 and 2.8)have the highest enrichment factors.Across climate zones,throughfall and stemflow show the lowest ion concentrations but the highest enrichment factors in extremely humid regions.Along the temperature gradient,ion concentrations are the highest in cold climates with no clear patterns observed for enrichment factors with increasing temperature.In addition,shrubs,conifers,mixed forests,and artificial ecosystems demonstrate enrichment factors 1.1 to 3.0 times greater than those of trees,broad-leaved plants,pure forests,and natural ecosystems.These findings emphasize the need for increased attentions to artificial ecosystems,such as urban and agricultural ecosystems,which often received
基金support provided by the National Natural Science Foundation of China Nos.51405048 and 51375519the China Postdoctoral Science Foundation No.2016M590861+2 种基金the Chongqing Research Program of Frontier and Application Foundation No.cstc2014jcyjA70010the Foundation of Municipal Education Committee of Chongqing No.KJ1705129the CQJTU Program of Study Abroad for Young Scholar for their support of this research.
文摘To investigate the dynamical load sharing behaviors of multi-floating components in the heavy load planetary gear system,a multi-floating planetary gear system that includes a floating central component and a quasi-floating planet flexible supporting pin is employed.Then a 21 degree of freedom lumped parameters dynamical model of this system is presented to study the dynamical load sharing behaviors.Some influencing factors,such as supporting stiffness,positions error of sun or carrier,and external input load are analyzed on the dynamical load sharing of the planetary gear system with multi-floating components.The results demonstrate that the load sharing condition of the system is best when both the sun gear and planet gears are multi-floating at the same time.When the planet gear position errors remain constant,reducing the flexible pin stiffness of planet gear or increasing external input load can effectively improve the load sharing.These conclusions are verified by the relevant experiments.
基金This work was jointly supported by the project of National Social Science Fund of China(17ZDA188)the National Natural Science Foundation of China(Grant Nos.41830648,41771453).
文摘The landscape index is a quantitative index which reflects characteristics of structure composition and spatial pattern in landscape studies,it is,therefore,expected to describe the spatial pattern of scientific research in bibliometric analysis.In this study,a novel attempt to regard scientific research as a kind of‘landscape’was made,and landscape indices were improved for bibliometric analysis to measure the spatial pattern of scientific research.For illustrating the feasibility of our method,global geoscience research from 1994 to 2018 was presented as a case.Moreover,spatiotemporal migration of landscape centroids was visualized.The results indicated that global geoscience publications increased steadily and articles were highly concentrated at the country level.The top 10 countries published 69.93%of total articles and 84.68%of geoscience articles were from top 20 productive countries.The spatial migration of centroids was mainly reflected in the longitude because of significant increasing of articles in eastern countries,especially in China with the growth rate of 747.14%.At the patch scale,the change trend of improved landscape indices verified the spatiotemporal changes of global distribution of geoscience articles.At the landscape scale,the strengthening of global international collaboration is the main driving forces of spatial heterogeneity of global geoscience research.This study is expected to help readers to understand global trends of geoscience research in the past 25 years,and to promote the development of bibliometric analysis towards the directions of spatialization and visualization.
