An Elastoplastic Fracture Model Based on Bond-Based Peridynamics

Fracture in ductile materials often occurs in conjunction with plastic deformation.However,in the bond-based peridynamic(BB-PD)theory,the classic mechanical stress is not defined inherently.This makes it difficult to describe plasticity directly using the classical plastic theory.To address the above issue,a unified bond-based peridynamics model was proposed as an effective tool to solve elastoplastic fracture problems.Compared to the existing models,the proposed model directly describes the elastoplastic theory at the bond level without the need for additional calculation means.The results obtained in the context of this model are shown to be consistent with FEM results in regard to force-displacement curves,displacement fields,stress fields,and plastic deformation regions.The model exhibits good capability of capturing crack propagation in ductile material failure problems.

An Updated Lagrangian Particle Hydrodynamics (ULPH)-NOSBPD Coupling Approach forModeling Fluid-Structure Interaction Problem

A fluid-structure interaction approach is proposed in this paper based onNon-Ordinary State-Based Peridynamics(NOSB-PD)and Updated Lagrangian Particle Hydrodynamics(ULPH)to simulate the fluid-structure interaction problem with large geometric deformation and material failure and solve the fluid-structure interaction problem of Newtonian fluid.In the coupled framework,the NOSB-PD theory describes the deformation and fracture of the solid material structure.ULPH is applied to describe the flow of Newtonian fluids due to its advantages in computational accuracy.The framework utilizes the advantages of NOSB-PD theory for solving discontinuous problems and ULPH theory for solving fluid problems,with good computational stability and robustness.A fluidstructure coupling algorithm using pressure as the transmission medium is established to deal with the fluidstructure interface.The dynamic model of solid structure and the PD-ULPH fluid-structure interaction model involving large deformation are verified by numerical simulations.The results agree with the analytical solution,the available experimental data,and other numerical results.Thus,the accuracy and effectiveness of the proposed method in solving the fluid-structure interaction problem are demonstrated.The fluid-structure interactionmodel based on ULPH and NOSB-PD established in this paper provides a new idea for the numerical solution of fluidstructure interaction and a promising approach for engineering design and experimental prediction.

Updated Lagrangian Particle Hydrodynamics (ULPH)Modeling of Natural Convection Problems

Natural convection is a heat transfer mechanism driven by temperature or density differences,leading to fluid motion without external influence.It occurs in various natural and engineering phenomena,influencing heat transfer,climate,and fluid mixing in industrial processes.This work aims to use the Updated Lagrangian Particle Hydrodynamics(ULPH)theory to address natural convection problems.The Navier-Stokes equation is discretized using second-order nonlocal differential operators,allowing a direct solution of the Laplace operator for temperature in the energy equation.Various numerical simulations,including cases such as natural convection in square cavities and two concentric cylinders,were conducted to validate the reliability of the model.The results demonstrate that the proposed model exhibits excellent accuracy and performance,providing a promising and effective numerical approach for natural convection problems.

非小细胞肺癌患者与健康对照组的脑皮层结构差异的回顾性研究

目的:分析非小细胞肺癌(non-small cell lung cancer,NSCLC)患者颅脑核磁共振影像学(magnetic resonance imaging,MRI)改变,并探讨其相关的影响因素,为患者的脑健康预防及保护提供依据。方法:选取2018年7月至2019年3月四川省肿瘤医院45例初诊为NSCLC(癌症组)及39例健康对照组(正常组)颅脑MRI数据,利用Freesurfer软件对MRI数据进行基于大脑皮层表面形态学测量(surface-based morphometry,SBM)分析,统计对比癌症组与正常组的脑区变化,利用偏相关分析方法将血常规、血脂、肿瘤标志物与变化脑区行相关性分析。结果:与正常组相比,癌症组右脑中央后回及顶叶上回脑皮质体积明显萎缩(P<0.05),但其厚度、表面积、曲率、脑沟深度未见明显变化(P>0.05)。此外,癌症组神经元特异性烯醇化酶(neuron-specific enolase,NSE)水平明显高于正常组[(27.02±33.16)ng/mL vs.(7.8±3.85)ng/mL,P<0.05],相关性分析结果显示中央后回体积萎缩与NSE呈负相关(r=-0.268,P=0.039),血常规、血脂、癌胚抗原(carcinoembryonic antigen,CEA)与中央后回体积萎缩无明显相关性。结论:NSCLC可导致右脑中央后回及顶叶上回体积缩小,且中央后回体积缩小与NSE呈显著负相关,提示NSE可作为预测NSCLC相关脑损伤的潜在预测分子。

Effects of neuregulin-1 on autonomic nervous system remodeling post-myocardial infarction in a rat model

Sympathetic nerve and vagus nerve remodeling play an important part in cardiac function post-myocardial infarction （MI）. Increasing evidence indicates that neuregulin-1 （NRG-1） improves cardiac function following heart failure. Since its impact on cardiac function and neural remodeling post-MI is poorly understood, we aimed to investigate the role of NRG-1 in autonomic nervous system remodeling post-MI. Forty-five Sprague-Dawley rats were equally randomized into three groups： sham （with the left anterior descending coronary artery exposed but without ligation）, MI （left anterior descending coronary artery ligation）, and MI plus NRG-1 （left anterior descending coronary artery ligation followed by intraperitoneal injection of NRG-1 （10 lag/kg, once daily for 7 days））. At 4 weeks after MI, echocardi- ography was used to detect the rat cardiac function by measuring the left ventricular end-systolic inner diameter, left ventricular diastolic diameter, left ventricular end-systolic volume, left ventricular end-diastolic volume, left ventricular ejection fraction, and left ventricular fractional shortening, mRNA and protein expression levels of tyrosine hydroxylase, growth associated protein-43 （neuronal specific pro- tein）, nerve growth factor, choline acetyltransferase （vagus nerve marker）, and vesicular acetylcholine transporter （cardiac vagal nerve fiber marker） in ischemic myocardia were detected by real-time PCR and western blot assay to assess autonomous nervous remodeling. After MI, the rat cardiac function deteriorated significantly, and it was significantly improved after NRG-1 injection. Compared with the MI group, mRNA and protein levels of tyrosine hydroxylase and growth associated protein-43, as well as choline acetyltransferase mRNA level significantly decreased in the MI plus NRG-1 group, while mRNA and protein levels of nerve growth factor and vesicular acetylcholine transporters, as well as choline acetyltransferase protein level slightly decreased. Our results indicate that NRG- 1 can improve cardiac function and regulate sympathetic and vagus nerve remodeling post-MI, thus reaching a new balance of the autonomic nervous system to protect the heart from injury.

A Rate-Dependent Peridynamic Model for the Dynamic Behavior of Ceramic Materials

In this study,a new bond-based peridynamic model is proposed to describe the dynamic properties of ceramics under impact loading.Ceramic materials show pseudo-plastic behavior under certain compressive loadings with high strain-rate,while the characteristic brittleness of the material dominates when it is subjected to tensile loading.In this model,brittle response under tension,softening plasticity under compression and strain-rate effect of ceramics are considered,which makes it possible to accurately capture the overall dynamic process of ceramics.This enables the investigation of the fracture mechanism for ceramic materials,during ballistic impact,in more detail.Furthermore,a bond-force updating algorithm is introduced to perform the numerical simulation and solve the derived equations.The proposed model is then used to analyze the dynamic response of ceramics tiles under impact loading to assess its validity.The results of damage development in ceramic materials are calculated and compared with the experimental results.The simulation results are consistent with the experiments,which indicates that the proposed rate-dependent peridynamic model has the capability to describe damage propagation in ceramics with good accuracy.Finally,based on a comparison between simulation and experimental results,it can be concluded that the damage results are in better agreement with experimental results than non-ordinary state-based peridynamic method.

Changes in Water Use Efficiency Caused by Climate Change,CO_(2) Fertilization,and Land Use Changes on the Tibetan Plateau

Terrestrial ecosystem water use efficiency(WUE)is an important indicator for coupling plant photosynthesis and transpiration,and is also a key factor linking the carbon and water cycles between the land and atmosphere.However,under the combination of climate change and human intervention,the change in WUE is still unclear,especially on the Tibetan Plateau(TP).Therefore,satellite remote sensing data and process-based terrestrial biosphere models(TBMs)are used in this study to investigate the spatiotemporal variations of WUE over the TP from 2001 to 2010.Then,the effects of land use and land cover change(LULCC)and CO_(2) fertilization on WUE from 1981-2010 are assessed using TBMs.Results show that climate change is the leading contributor to the change in WUE on the TP,and temperature is the most important factor.LULCC makes a negative contribution to WUE(-20.63%),which is greater than the positive contribution of CO_(2) fertilization(11.65%).In addition,CO_(2) fertilization can effectively improve ecosystem resilience on the TP.On the northwest plateau,the effects of LULCC and CO_(2) fertilization on WUE are more pronounced during the driest years than the annual average.These findings can help researchers understand the response of WUE to climate change and human activity and the coupling of the carbon and water cycles over the TP.

Analyzing acetylene adsorption of metal-organic frameworks based on machine learning

Metal-organic frameworks(MOFs) containing open metal sites are important materials for acetylene(C_(2)H_(2)) adsorption.However,it is inefficient or even impossible to search suitable MOFs by molecular simulation method in nearly infinite MOFs space.Therefore,machine learning(ML) methods are adopted in the material screening and prediction of high-performance MOFs.In this paper,architecture,chemical and structural features are used to analyze the C_(2)H_(2) adsorption performance of the MOFs.Different ML algorithms are applied to perform classification and regression analysis to the factors affecting material adsorption.By decision tree(DT) algorithm,it is found that only PV,GSA,and Cu-OMS are sufficient to determine the high adsorption of the MOFs.Furthermore,the influence of topology on the performance of MOFs is obtained.Gradient Boosting Decision Tree(GBDT),Support Vector Machine(SVM),and Back Propagation Neural Network(BPNN),are introduced to analyze the quantitative structure-property relationship(QSPR) between C_(2)H_(2) adsorption and the features of MOFs.The prediction of the GBDT model is found to have the highest accuracy,with R~2 as 0.93 and RMSE as 11.58.In addition,the GBDT model is used for feature analysis,and the contribution of each feature to the performance is obtained,which is of great significance for the design and analysis of MOFs.The successful application of ML to MOFs screening greatly reduce the calculation time and provides important reference for the design and synthesis of new MOFs.

Effects of Transgenic Bt+CpTI Cotton Cultivation on Functional Diversity of Microbial Communities in Rhizosphere Soils

[Objective] This study aimed to investigation the effects of tranagenic Bt ＋ CpTI cotton cultivation on functional diversity of microbial communities in rhizospbere soils. E Method] By using the Biolog method, a comparative study was conducted on the utilization level of single carbon source by microbes in the rhi- zosphere soils of transgenic Bt ＋ CpTI cotton sGK321 and its parental conventional cotton ＇ Shiyuan 321＇ at different growth stages. [ Result ] The results showed that, compared with the parental conventional cotton, the average well-color development （AWCD） value of micmhial communities in rhizospbere soils of transgenie Bt ＋ CpTI cotton were significantly higher （P 〈 O. 05） at seedling stage and budding stage while significantly lower at flower and boll stage and bell opening stage. Shannon-Wiener diversity index （H） and Simpson dominance index （D） of microbial communities in rhlzesphere soils of transgenic cotton and conventional cotton varied with the different growth stages, whereas the Shannon-Wiener evenness index （E） showed no significant difference between transgenie cotton and convention- al cotton at four growth stages. Principal component analysis indicated that the patterns of carbon source utilization by microbial communities in rhizospbere soils were similar among transgenic cotton at seeding stage and flower and boll stage and parental conventional cotton at seeding stage and budding stage, which were also similar between tranagenic cotton at budding stage and parental conventional cotton at flower and boll stage. [ Conclusion] Analysis of different carbon sources indi- cated that the main carbon sources utilized by soil microbes were carbohydrates, amino acids, carboxylie acids and polymers.

Research for length change of four seasons over China in recent 47 years

Using daily temperature data from 599 Chinese weather stations during 1961-2007, the length change trends of four seasons dur- ing the past 47 years were analyzed. Results show that throughout the region, four seasons＇ lengths are： spring becomes shorter （-0.8 d/10yrs）, summer becomes longer （3.2 d/10yrs）, autumn （-0.5 d/10yrs） and winter （-1.6 d/10yrs） becomes shorter. This trend is different in spatial distribution, namely it is very obvious in northern than southern China, and also remarkable in eastern than western China. Summer change is most obvious, but autumn has little change comparatively. This trend is highly obvious in North, East, Central and South China. In the Southwest starting in the 21st century, summer becomes longer and winter shortens. The trend in the Plateau region since the 1980s is that spring becomes longer and winter shortens. The average annual temperature increased during the past 47 years, and the change of the average annual temperature precedes seasons＇ length. Thus, the average annual temperature has a certain influence on the length change of seasons.

Design of a graphene oxide@melamine foam/polyaniline@erythritol composite phase change material for thermal energy storage

At present,only a single modification method is adopted to improve the shortcomings of erythritol(ET)as a phase change material(PCM).Compared with a single modification method,the synergistic effect of multiple modification methods can endow ET with comprehensive performance to meet the purpose of package,supercooling reduction,and enhancement of thermal conductivity.In this work,we innovatively combine graphene oxide(GO)nanosheet modified melamine foam(MF)and polyaniline(PANI)to construct a novel ET-based PCM by blending and porous material adsorption modification.PANI as the nucleation center can enhance the crystallization rate,thereby reducing the supercooling of ET.Meanwhile,GO@MF foam can not only be used as a porous support material to encapsulate ET but also as a heat conduction reinforcement to improve heat storage and release rate.As a result,the supercooling of GO@MF/PANI@ET(GMPET)composite PCM decreases from 91.2℃ of pure ET to 57.9℃ and its thermal conductivity(1.58 W·m^(-1)·K^(-1))is about three times higher than that of pure ET(0.57 W·m^(-1)·K^(-1)).Moreover,after being placed at 140℃ for 2 h,there is almost no ET leakage in the GMPET composite PCM,and the mass loss ratio is less than 0.75%.In addition,the GMPET composite PCM displays a high melting enthalpy of about 259 J·g^(-1) and a high initial mass loss temperature of about 198℃.Even after the 200th cycling test,the phase transition temperature and the latent heat storage capacity of the GMPET PCM all remain stable.This work offers an effective and promising strategy to design ET-based composite PCM for the field of energy storage.

The establishment of Boron nitride@sodium alginate foam/polyethyleneglycol composite phase change materials with high thermal conductivity, shape stability, and reusability

Adopting organic phase change materials(PCMs) for the management of electronic devices is restricted by low thermal conductivity. In this paper, the composite PCMs are established by freeze-drying and vacuum impregnation. Herein, polyethylene glycol(PEG) is induced as heat storage materials, boron nitride(BN) is embedded as filler stacking in an orderly fashion on the foam walls to improve thermal conductivity and sodium alginate(SA) is formed as supporting material to keep the shape of the composite stable. X-ray diffractometry, scanning electron microscopy-energy dispersive spectrometer, thermal gravimetric analysis, thermal conductivity meter, differential scanning calorimeter, and Fourier transform infrared were used to characterize the samples and thermal cycles were employed to measure the shape stability. The results exhibit the BN@SA/PEG composite PCMs have good chemical compatibility, stable morphology, and thermal stability. Due to the high porosity of foam, PEG endows the composite PCMs with high latent heat(149.11 and 141.59 J·g^(-1)). Simultaneously, BN@SA/PEG shows an excellent heat performance with high thermal conductivity(0.99 W·m^(-1)·K^(-1)), reusability, and shape stability, contributing the composite PCMs to application in the energy storage field. This study provides a strategy to manufacture flexible, long-serving, and shape-stable PCMs via introducing BN@SA foam as a storage framework, and these PCMs have great potential in thermal management in the electronic field.

Mitigating thermal runaway hazard of high-energy lithium-ion batteries by poison agent

Lithium-ion batteries with high-energy density are extensively commercialized in long-range electric vehicles. However, they are poor in thermal stability and pose fire or explosion, which has attracted the global attention. This study describes a new route to mitigate the battery thermal runaway(TR) hazard by poison agents. First, the self-destructive cell is built using the embedded poison layer. Then, the poisoning mechanism and paths are experimentally investigated at the material, electrode, and cell levels. Finally, the proposed route is verified by TR tests. The results show the TR hazard can be significantly reduced in the self-destructive cell based on a new reaction sequence regulation. Specifically, the maximum temperature of the self-destructive cell is more than 300℃ lower than that of the normal cell during TR. The drop in maximum temperature can reduce total heat release and the probability of TR propagation in the battery system, significantly improving battery safety.

Implementation of OpenMP Parallelization of Rate-Dependent Ceramic Peridynamic Model

A rate-dependent peridynamic ceramic model,considering the brittle tensile response,compressive plastic softening and strain-rate dependence,can accurately represent the dynamic response and crack propagation of ceramic materials.However,it also considers the strain-rate dependence and damage accumulation caused by compressive plastic softening during the compression stage,requiring more computational resources for the bond force evaluation and damage evolution.Herein,the OpenMP parallel optimization of the rate-dependent peridynamic ceramicmodel is investigated.Also,themodules that compute the interactions betweenmaterial points and update damage index are vectorized and parallelized.Moreover,the numerical examples are carried out to simulate the dynamic response and fracture of the ceramic plate under normal impact.Furthermore,the speed-up ratio and computational efficiency by multi-threads are evaluated and discussed to demonstrate the reliability of parallelized programs.The results reveal that the totalwall clock time has been significantly reduced after optimization,showing the promise of parallelization process in terms of accuracy and stability.

Peridynamic Modeling of Brittle Fracture in Mindlin-Reissner Shell Theory

In this work,wemodeled the brittle fracture of shell structure in the framework of Peridynamics Mindlin-Reissener shell theory,in which the shell is described by material points in themean-plane with its drilling rotation neglected in kinematic assumption.To improve the numerical accuracy,the stress-point method is utilized to eliminate the numerical instability induced by the zero-energy mode and rank-deficiency.The crack surface is represented explicitly by stress points,and a novel general crack criterion is proposed based on that.Instead of the critical stretch used in common peridynamic solid,it is convenient to describe thematerial failure by using the classic constitutive model in continuum mechanics.In this work,a concise crack simulation algorithm is also provided to describe the crack path and its development,in order to simulate the brittle fracture of the shell structure.Numerical examples are presented to validate and demonstrate our proposed model.Results reveal that our model has good accuracy and capability to represent crack propagation and branch spontaneously.

NaGd_(0.4)Eu_(0.6)Mg_(1-x)Zn_(x)WO_(6)solid solution red phosphors:Microstructure variation and luminescence enhancement induced by Zn^(2+)-doping

Red phosphor is an important component of the phosphor-converted white light-emitting diodes(pcWLEDs).The development of the novel red phosphor with excellent luminescence properties is of great significance for high performance WLEDs.In this study,NaGd_(0.4)Eu_(0.6)Mg_(1-x)Zn_(x)WO_(6)red phosphors with excellent luminescence properties were successfully synthesized and systematically investigated.Our results show that the Zn^(2+)-doping concentration has significant effect on the microstructures and luminescence properties of the NaGd_(0.4)Eu_(0.6)Mg_(1-x)Zn_(x)WO_(6)phosphors.The NaGd_(0.4)Eu_(0.6)Mg_(1-x)ZnxWO_(6)(0≤x≤0.7)samples are well crystallized pure solid solution sub-microcrystals,whereas the phase purity gradually decreases at 0.7<x≤1.0.The NaGd_(0.4)Eu_(0.6)Mg_(1-x)ZnxWO_(6)(0<x≤0.5)phosphors have stronger emissions than NaGd_(0.4)Eu_(0.6)MgWO_(6),and the optimized NaGd_(0.4)Eu_(0.6)Mg_(0.9)Zn_(0.1)WO_(6)phosphor possesses the best luminescence properties including thermal stability,CIE chromaticity coordinate,life time and quantum yield.The packaged WLED using NaGd_(0.4)Eu_(0.6)Mg_(0.9)Zn_(0.1)WO_(6)phosphor emits bright white light with higher CRI,lower CCT,and chromaticity coordinate close to the pure white light.The developed NaGd_(0.4)Eu_(0.6)Mg_(1-x)Zn_(x)WO_(6)phosphors have potential application in lighting and display.This work can offer an effective strategy for boosting luminescence properties of tungstate phosphors with the double perovskite structure.

Retinoic acid alleviates rotavirus-induced intestinal damage by regulating redox homeostasis and autophagic flux in piglets

Rotaviruses(RV)are a major cause of severe gastroenteritis,particularly in neonatal piglets.Despite the availability of effective vaccines,the development of antiviral therapies for RV remains an ongoing challenge.Retinoic acid(RA),a metabolite of vitamin A,has been shown to have anti-oxidative and antiviral properties.However,the mechanism by which RA exerts its intestinal-protective and antiviral effects on RV infection is not fully understood.The study investigates the effects of RA supplementation in Duroc×Landrace×Yorkshire(DLY)piglets challenged with RV.Thirty-six DLY piglets were assigned into six treatments,including a control group,RA treatment group with two concentration gradients(5and 15 mg/d),RV treatment group,and RV treatment group with the addition of different concentration gradients of RA(5 and 15 mg/d).Our study revealed that RV infection led to extensive intestinal architecture damage,which was mitigated by RA treatment at lower concentrations by increasing the villus height and villus height/crypt depth ratio(P<0.05),enhancing intestinal stem cell signaling and promoting intestinal barrier functions.In addition,15 mg/d RA supplementation significantly increased NRF2 and HO-1 protein expression(P<0.05)and GSH content(P<0.05),indicating that RA supplementation can enhance anti-oxidative signaling and redox homeostasis after RV challenge.Additionally,the research demonstrated that RA exerts a dual impact on the regulation of autophagy,both stimulating the initiation of autophagy and hindering the flow of autophagic flux.Through the modulation of autophagic flux,RA influence the progression of RV infection.These findings provide new insights into the regulation of redox hemostasis and autophagy by RA and its potential therapeutic application in RV infection.

Relationship between Atmospheric Heat Source over the Tibetan Plateau and Precipitation in the Sichuan–Chongqing Region during Summer

NCEP-NCAR reanalysis data and a 47-yr daily precipitation dataset from a network of 42 rain gauges are used to analyze the atmospheric heat source （〈Q1〉） anomaly over the Tibetan Plateau （TP） and its influence on the summer precipitation anomaly in the Sichuan-Chongqing region. Results show that the vertical advection of 〈Ql〉 over the central TP is a major factor affecting summer precipitation in the Sichuan-Chongqing region. When the vertical ad- vection of〈Q1〉 over the central TP is strengthened, the South Asian high shifts further than normal to the south and east, the western Pacific subtropical high shifts further than normal to the south and west, and the Indian low weak- ens. This benefits the transport of warm moist air from the low latitude oceans to the Sichuan-Chongqing region. Correspondingly, in the high latitudes, two ridges and one trough form, which lead to cool air moving southward. These two air masses converge over the Sicbuan -chongqing region, leading to significant precipitation. In contrast, when the vertical advection of 〈Q1〉 over the central TP is weakened, the South Asian high moves to the north and west, the subtropical high moves eastward and northward, and the Indian low strengthens. This circulation pattern is unfavorable for warm air advection from the south to the Sichuan-Chongqing region, and the cool air further north cannot move southward because of the presence of two troughs and one ridge at high latitude. Thus, ascent over the Sichuan-Chongqing region is weakened, resulting in less precipitation.

Differences in Atmospheric Heat Source between the Tibetan Plateau–South Asia Region and the Southern Indian Ocean and Their Impacts on the Indian Summer Monsoon Outbreak

In this paper, the NCEP-NCAR daily reanalysis data are used to investigate the characteristics of the atmospheric heat source/sink （AHSS） over South Asia （SA） and southern Indian Ocean （SIO）. The thermal differences between these two regions and their influence on the outbreak of the Indian summer monsoon （ISM） are explored. Composite analysis and correlation analysis are applied. The results indicate that the intraseasonal variability of AHSS is signi- ficant in SA but insignificant in the SIO. Large inland areas in the Northern Hemisphere still behave as a heat sink in March, similar to the situation in winter. Significant differences are found in the distribution of AHSS between the ocean and land, with distinct land-ocean thermal contrast in April, and the pattern presents in the transitional period right before the ISM onset. In May, strong heat centers appear over the areas from the Indochina Peninsula to the Bay of Bengal and south of the Tibetan Plateau （TP）, which is a typical pattern of AHSS distribution during the monsoon season. The timing of SA-SIO thermal difference turning positive is about 15 pentads in advance of the onset of the ISM. Then, after the thermal differences have turned positive, a pre-monsoon meridional circulation cell develops due to the near-surface heat center and the negative thermal contrast center, after which the meridional circulation of the ISM gradually establishes. In years of early （late） conversion of the SASIO thermal difference turning from neg- ative to positive, the AHSS at all levels over the TP and SIO converts later （earlier） than normal and the establish- ment of the ascending and descending branches of the ISM＇s meridional circulation is later （earlier） too. Meanwhile, the establishment of the South Asian high over the TP is later （earlier） than normal and the conversion of the Mas- carene high from winter to summer mode occurs anomalously late （early）. As a result, the onset of the ISM is later （earlier） than normal. However, the difference in vorticity between early and late conversion only shows in the changes of strong vorticity centers＇ location in the upper and lower troposphere.

Controllable synthesis of Tb-based metal-organic frameworks as an efficient fluorescent sensor for Cu^(2+)detection

A series of Tb-based metal-organic frameworks(Tb-MOFs)were successfully synthesized by a solvothermal method.The size and morphology of the as-obtained Tb-MOFs can be effectively controlled via regulating the experimental conditions such as the volume fraction of DMF and the molar ratio of Tb^(3+)to NaOH.It is found that all the samples exhibit strong green emissions under ultraviolet excitation,corresponding to^(5)D_(4)→^(7)F_(J)transitions of Tb^(3+).Interestingly,Tb-MOFs displayed an efficient and distinct luminescence quenching by Cu^(2+)in aqueous solutions.The competitive fluorescence detection experiments indicate that these Tb-MOFs sensors can be used as a high selective and sensitive sensor of Cu^(2+)detection with the detection limit of 10μmol·L^(-1),which can be used as a promising fluorescence sensor for Cu^(2+)detection in daily life.