Temperature dependence of mechanical properties and damage evolution of hot dry rocks under rapid cooling

Understanding the differences in mechanical properties and damage characteristics of granitoid under high temperatures is crucial for exploring deep geothermal resources.This study analyzes the evolution of the acoustic emission(AE)characteristics and mechanical parameters of granodiorite and granite after heating and water cooling by uniaxial compression and variable-angle shear tests under different temperature gradients.We identify their changes in mesostructure and mineral composition with electron probe microanalysis and scanning electron microscopy.Results show that these two hot dry rocks have similar diagenetic minerals and microstructure,but show significantly different mechanical and acoustic characteristics,and even opposing evolution trends in a certain temperature range.At the temperatures ranging from 100℃to 500℃,the compressive and shear mechanical properties of granodiorite switch repeatedly between weakening and strengthening,and those of granite show a continuous weakening trend.At 600℃,both rocks exhibit a deterioration of mechanical properties.The damage mode of granite is characterized by initiating at low stress,exponential evolutionary activity,and intensified energy release.In contrast,granodiorite exhibits the characteristics of initiating at high stress,volatile evolutionary activity,and intermittent energy release,due to its more stable microstructure and fewer thermal defects compared to granite.As the temperature increases,the initiation and propagation of secondary cracks in granodiorite are suppressed to a certain extent,and the seismicity and brittleness are enhanced.The subtle differences in grain size,microscopic heterogeneity,and mineral composition of the two hot dry rocks determine the different acoustic-mechanical characteristics under heating and cooling,and the evolution trends with temperature.These findings are of great significance for the scientific and efficient construction of rock mass engineering by rationally utilizing different rock strata properties.

Energy Storage Operation Modes in Typical Electricity Market and Their Implications for China

As the Chinese government proposes ambitious plans to promote low-carbon transition,energy storage will play a pivotal role in China’s future power system.However,due to the lack of a mature electricity market environment and corresponding mechanisms,current energy storage in China faces problems such as unclear operational models,insufficient cost recovery mechanisms,and a single investment entity,making it difficult to support the rapid development of the energy storage industry.In contrast,European and American countries have already embarked on certain practices in energy storage operation models.Through exploration of key issues such as investment entities,market participation forms,and cost recovery channels in both front and back markets,a wealth of mature experiences has been accumulated.Therefore,this paper first summarizes the existing practices of energy storage operation models in North America,Europe,and Australia’s electricity markets separately from front and back markets,finding that perfect market mechanisms and reasonable subsidy policies are among the main drivers for promoting the rapid development of energy storage markets.Subsequently,combined with the actual development of China’s electricity market,it explores three key issues affecting the construction of costsharing mechanisms for energy storage under market conditions:Market participation forms,investment and operation modes,and cost recovery mechanisms.Finally,in line with the development expectations of China’s future electricitymarket,suggestions are proposed fromfour aspects:Market environment construction,electricity price formation mechanism,cost sharing path,and policy subsidy mechanism,to promote the healthy and rapid development of China’s energy storage industry.

Three Dimensions of Cultivating New Generations: Value Implication, Scientific Connotation, and Cultivation Path

The new generation of the times is the latest requirement for young people in the new era,and it is the latest training goal for young people put forward by the Party and the country in the face of the second centennial goal.At the 19th National Congress,it was put forward by the country that the concept of“new generation of the times”for the first time,indicating the training direction and theoretical guidance for the new generation of the times.The new age requires young people to have firm ideals and beliefs,excellent skills,and a great spirit of responsibility.The proposition of cultivating a new generation of the times is a deep exploration and summary of Marx’s theory of“all-round human development,”Lenin’s youth view and the education view of excellent traditional Chinese culture,and the proposition needs to strengthen the leadership of the Party,give play to the leading role of socialist core values,and the youth themselves should actively act to realize the transformation of theoretical and practical results.

Implications for rock instability precursors and principal stress direction from rock acoustic experiments

The characteristics of rock instability precursors and the principal stress direction are very crucial for the prevention of geological disasters.This study investigated the qualitative relationship between rock instability precursors and principal stress direction through wave velocity in rock acoustic emission(AE)experiments.Results show that the wave velocity variation exhibits obvious anisotropic characteristics in 0%–20%and 60%–90%of peak strength due to the differences of stress-induced microcrack types.The amplitude of wave velocity variation is related to the azimuth and position of wave propagation path,which indicates that the principal stress direction can be identified by the anisotropic characteristics of wave velocity variations.Furthermore,the experiments also demonstrate that the AE event rate and wave velocity show quiet and stable variations in the elastic stage of rock samples,while they present a trend of active and unstable variations in the plastic stage.It implies that both the AE event rate and wave velocity are effective monitoring parameters for rock instability.The anisotropic characteristics of the wave velocity variation and AE event rate are beneficial complements for identifying the rock instability precursors and determining the principal stress direction,which provides a new analysis method for stability monitoring in practical rock engineering.

Implications for identification of principal stress directions from acoustic emission characteristics of granite under biaxial compression experiments

The rock fracture characteristics and principal stress directions are crucial for prevention of geological disasters.In this study,we carried out biaxial compression tests on cubic granite samples of 100 mm in side length with different intermediate principal stress gradients in combination with acoustic emission(AE)technique.Results show that the fracture characteristics of granite samples change from‘sudden and aggregated’to‘continuous and dispersed’with the increase of the intermediate principal stress.The effect of increasing intermediate principal stress on AE amplitude is not significant,but it increases the proportions of high-frequency AE signals and shear cracks,which in turn increases the possibility of unstable rock failure.The difference of stress in different directions causes the anisotropy of rock fracture and thus leads to the obvious anisotropic characteristics of wave velocity variations.The anisotropy of wave velocity variations with stress difference is probable to identify the principal stress directions.The AE characteristics and the anisotropy of wave velocity variations of granite under two-dimensional stress are not only beneficial complements for rock fracture characteristic and principal stress direction identification,but also can provide a new analysis method for stability monitoring in practical rock engineering.

基于多声源波速结构成像的岩体异常区域超前辨识方法

异常区域超前辨识对于预防地下岩土工程灾害具有重要作用。为了满足地下工程高精度探测的需求,本文提出一种层析成像方法以辨识复杂岩体结构中的异常区域,结合了走时层析、阻尼最小二乘和高斯滤波等技术。该方法克服了空洞区域辨识中速度差限制,减轻了迭代中孤立速度突变所带来的影响。我们开展了数值和室内实验量化评估最短路径法(Shortest-Path Method,SPM)、动态最短路径法(Dynamic Shortest-Path Method,DSPM)和快速扫描法(Fast Sweeping Method,FSM)等正演模拟的识别精度和计算效率。结果表明,在数值和室内实验中DSPM和FSM均能清晰地辨识出异常区域。陕西震奥矿山现场应用结果证明了该方法可利用矿山开采中爆破、微震等多类声源对矿山内部未知结构进行波速场成像。本研究不仅实现了走时层析成像方法在异常区域识别中的应用,而且为地下岩土工程中潜在风险源的探测提供了新的思路。

Genome-wide identification and expression analysis of NtbHLH gene family in tobacco(Nicotiana tabacum)and the role of NtbHLH86 in drought adaptation

The bHLH transcription factors play pivotal roles in plant growth and development,production of secondary metabolites and responses to various environmental stresses.Although the bHLH genes have been well studied in model plant species,a comprehensive investigation of the bHLH genes is required for tobacco with newly obtained high-quality genome.In the present study,a total of 309 NtbHLH genes were identified and can be divided into 23 subfamilies.The conserved amino acids which are essential for their function were predicted for the NtbHLH proteins.Moreover,the NtbHLH genes were conserved during evolution through analyzing the gene structures and conserved motifs.A total of 265 NtbHLH genes were localized in the 24 tobacco chromosomes while the remained 44 NtbHLH genes were mapped to the scaffolds due to the complexity of tobacco genome.Moreover,transcripts of NtbHLH genes were obviously tissue-specific expressed from the gene-chip data from 23 tobacco tissues,and expressions of 20 random selected NtbHLH genes were further confirmed by quantitative real-time PCR,indicating their potential functions in the plant growth and development.Importantly,overexpressed NtbHLH86 gene confers improve drought tolerance in tobacco indicating that it might be involved in the regulation of drought stress.Therefore,our findings here provide a valuable information on the characterization of NtbHLH genes and further investigation of their functions in tobacco.

原发灶不明肿瘤诊疗进展与展望

原发灶不明肿瘤(cancer of unknown primary,CUP)是一种细胞异质性显著并且具有高度恶性表型的转移性疾病,并且很难通过常规的检查手段被检测出其原发灶。一些新的检测手段,如基因表达谱检测、肿瘤表观遗传学检测、液体活检等手段逐渐应用于CUP原发灶的确定上,基于此出现的器官特异性治疗、靶向治疗、免疫治疗等也均有较大的应用前景,其有望提高CUP患者诊断的精确性和特异性,延长患者生存时间,改善患者生存质量。本文针对CUP的前沿诊断技术和治疗选择及其进展进行综述。

Factors influencing online information acquisition: The case of Chinese college students

Purpose： This study intends to examine the factors that influence Chinese college students＇ use of the lnternet for acquiring information. Design/methodology/approach： This paper developed the research model by using the technology acceptance model （TAM） and information system success model as the theoretical foundation. The proposed model was empirically tested with the structural equation modeling technique based on data collected from a survey of 357 college students. Findings： The results show that 1） perceived ease of use, perceived usefulness and perceived playfulness all have a positive impact on the intention to use the Internet for acquiring information, 2） use context and system quality significantly influence perceived usefulness and perceived ease of use, and 3） service quality has a positive impact on perceived ease of use but not on perceived usefulness. Likewise information quality has no positive effect on perceived usefulness. Research limitations： The survey respondents were mainly from college students in Nanjing. We need to recruit college students in the western or other developing areas in China to further validate our findings. Practical implications： This study puts forward some feasible suggestions for university libraries to improve information organization and the use of digital library resources to better meet the needs of library users. Originality/value： This study provides insights into the understanding of the factors affecting college students＇ online information acquisition from multiple perspectives.

A molecular toolkit to boost functional genomic studies in transformation-recalcitrant vegetable legumes

Dear Editor Legumes,the second-largest family of crops,contribute over one-third of human dietary proteins.Soybean(Glycine max L.),common bean(Phaseolus vulgaris L.),pea(Pisum sativum L.),and cowpea(Vigna unguiculata L.)are among the most widely culti-vated crop legumes for grain and vegetable and are essential for food security globally.

Investigation and Research on Safety Education in Village Elementary Schools in Counties ——With Nanxian County, Hunan as an Example

The basic education in the new period has changed quickly, and all kinds of education departments have strengthened safety education by various approaches;however, the students' safety accidents across the country have still happened frequently, so the people have spontaneously paid attention to and reflected on the students' safety education issue, especially the safety education in the elementary schools where the students are younger. In this paper, the village elementary schools in the counties have been taken as the research object, and the research methods such as documentary method and interview method have been adopted to analyze the current situation of safety education in the village elementary schools in Nanxian County from the aspects such as safety education management, safety education content, safety education awareness, safety education effect and safety education approach.

Random Terpolymer Based on Simple Siloxane-functionalized Thiophene Unit Enabling High-performance Non-fullerene Organic Solar Cells

Incorporation of siloxane-functionalized units into polymers backbone has proven to be an efficient strategy to improve photovoltaic performance. In this work, a low-cost siloxane-containing unit was developed to construct a series of terpolymers, and the effects of siloxane on the polymer performance were systematically studied. Different contents of thiophene containing siloxane-functionalized side chain were introduced into PM6 to obtain a series of polymers(PM6, PM6-SiO-10, PM6-SiO-20 and PM6-SiO-30). The siloxane-functionalized side chains in polymers have only a slight effect on the absorption behavior and frontier molecular orbitals. However, when the siloxane content increased, the terpolymers' aggregation property decreased and the temperature-dependency increased, leading to improved donor-acceptor compatibility. The power conversion efficiency(PCE) based on PM6:Y6, PM6-SiO-20:Y6 and PM6-SiO-30:Y6 devices was 15.64%, 16.03% and 15.82%, respectively. In comparison, the active layer based on PM6-SiO-10:Y6 exhibits the most appropriate phase separation morphology, resulting in effective exciton dissociation, more balanced hole-electron transport and less recombination. Consequently, the highest PCE of 16.69% with an outstanding shortcircuit current density of 26.96 mA·cm^(-2) was obtained, which are one of the highest values for siloxane-functionalized polymer-based devices.This work demonstrates that finely controlling the content of siloxane-functionalized thiophene is beneficial for obtaining high-performance terpolymer donors and provides a novel and low-cost method to improve photovoltaic performance.

Highly crystalline,highly stable n-type ultrathin crystalline films enabled by solution blending strategy toward organic single-crystal electronics

The development of n-type semiconductor is still far behind that of p-type semiconductor on account of the challenges in enhancing carrier mobility and environmental stability.Herein,by blending with the polymers,n-type ultrathin crystalline thin film was successfully prepared by the method of meniscus-guided coating.Remarkably,the n-type crystalline films exhibit ultrathin thickness as low as 5 nm and excellent mobility of 1.58 cm^(2) V^(-1) s^(-1),which is outstanding in currently reported organic n-type transistors.Moreover,the PS layer provides a high-quality interface with ultralow defect which has strong resistance to external interference with excellent long-term stability,paving the way for the application of n-type transistors in logic circuits.

异源过表达水稻OsSAPP3基因促进拟南芥叶片衰老

蛋白磷酸酶催化的蛋白质可逆磷酸化反应是叶片衰老的关键环节。该研究筛选并克隆了1个新的参与水稻(Oryza sativa)叶片衰老调控的PP2C基因OsSAPP3。研究表明,OsSAPP3的启动子在Pro_(OsSAPP3)-GUS转基因拟南芥(Arabidopsis thaliana)的莲座叶中有活性,并且活性以依赖叶龄方式增加。利用CaMV 35S启动子驱动组成型异源过表达OsSAPP3导致转基因拟南芥无法正常生长。用可诱导型启动子GVG系统驱动OsSAPP3异源过表达导致转基因拟南芥出现莲座叶变小、数量增加、叶片早衰及抽薹开花提前等早衰表型。外源诱导OsSAPP3基因异源过表达后,利用实时荧光定量PCR检测到SAG12、WRKY6和NAC2等衰老标志基因显著上调表达。研究结果表明, OsSAPP3是参与水稻叶片衰老的正向调控因子。

Geochronology and Geochemistry of Middle–Late Ordovician Granites and Gabbros in the Erguna Region,NE China:Implications for the Tectonic Evolution of the Erguna Massif

Zircon U-Pb ages, Hf isotope data and whole-rock major and trace element data for the Middle to Late Ordovician gabbros and granites in the Erguna Massif, NE China were presented in this paper. The petrogenesis of these rocks and the Early Paleozoic tectonic evolution of the massif were discussed. Zircons from the granites and gabbros are of magmatic origin based on their cathodoluminescence（CL） images. The 206Pb/238 U ages obtained from 20 spots on zircons from the granites range from 446±9 to 464±10 Ma, yielding a weighted mean age of 455±10 Ma; and 16 spots on zircons from the gabbros range from 465±10 to 466±7 Ma, yielding a weighted mean age of 465±2 Ma. Chemically, the Late Ordovician granites in the Erguna Massif are weakly peraluminous and similar to A-type granites. The granites and gabbros are all enriched in light rare earth elements and large ion lithophile elements（e.g., Rb, K）, and depleted in heavy rare earth elements and high field strength elements（e.g., Nb, Ta, and Ti）; they all exhibit marked negative Eu anomalies. Their zircon εHf（t） values range mainly from ＋1.86 to ＋6.21（for the granites） and ＋1.39 to ＋3.89（for the gabbros）, except for one spot with a value of-0.27（for a gabbro）. The TDM1 ages for the gabbros and TDM2 ages for the granites vary from 928 to 1 091 Ma and from 1 287 to 1 675 Ma, respectively. It is concluded that the primary magma of the granites could have been derived by partial melting of Mesoproterozoic newly accreted crustal material, whereas the primary magma of the gabbros originated by partial melting of a depleted mantle wedge that had been metasomatized by fluids derived from a subducted slab. These Middle-Late Ordovician granites and gabbros constitute a typical bimodal igneous rock association, implying an extensional environment that was probably related to the post-collisional development of the Erguna and Xing＇an massifs in the early Early Paleozoic.

锰铝二元水滑石和锰铁铝三元水滑石对U(Ⅵ)的高效去除及其机理研究

本文采用一步水热法制备了新型低成本的二元水滑石(MnAl-LDHs)和三元水滑石(MnFeAl-LDHs)吸附剂,并利用扫描电子显微镜(SEM)、傅里叶变换红外光谱(FTIR)、X射线粉末衍射仪(XRD)和X射线光电子能谱(XPS)等微观表征技术分析了材料的物理化学性质,通过静态批示实验和光谱分析研究了U(Ⅵ)在MnAl-LDHs和MnFeAl-LDHs上的吸附行为和相互作用机理.宏观实验结果表明, MnAl-LDHs和MnFeAl-LDHs对U(Ⅵ)的吸附在60 min内都达到了平衡,且在pH=5.0条件下三元MnFeAl-LDHs对U(Ⅵ)呈现出较高的吸附量(157.73 mg/g),是U(Ⅵ)在二元MnAl-LDHs上饱和吸附量(70.72 mg/g)的两倍.此外, MnFeAl-LDHs在高盐度、复杂共存离子环境下和不同水体系中依然表现出优越的吸附性能. FTIR和XPS光谱分析结果表明, U(Ⅵ)不仅可以与材料表面的–OH和层间CO32-形成较强的络合,还能与水滑石中的部分Mn^(2+)发生取代反应.本文的研究揭示了含锰水滑石材料在高效修复放射性废水中的吸附机理和潜在的应用前景.

Simulation of urban expansion based on cellular automata and maximum entropy model

Urban expansion is a hot topic in land use/land cover change(LUCC)researches.In this paper,maximum entropy model and cellular automata(CA)model are coupled into a new CA model(Maxent-CA)for urban expansion.This model can help to obtain transition rules from single-period dataset.Moreover,it can be constructed and calibrated easily with several steps.Firstly,Maxent-CA model was built by using remote sensing data of China in 2000(basic data)and spatial variables(such as population density and Euclidean distance to cities).Secondly,the proposed model was calibrated by analyzing training samples,neighborhood structure and spatial scale.Finally,this model was verified by comparing logistic regression CA model and their simulation results.Experiments showed that suitable sampling ratio(sampling ratio equals the proportion of urban land in the whole region)and von Neumann neighborhood structure will help to yield better results.Spatial structure of simulation results becomes simple as spatial resolution decreases.Besides,simulation accuracy is significantly affected by spatial resolution.Compared to simulation results of logistic regression CA model,Maxent-CA model can avoid clusters phenomenon and obtain better results matching actual situation.It is found that the proposed model performs well in simulating urban expansion of China.It will be helpful for simulating even larger study area in the background of global environment changes.

VEGF-B prevents excessive angiogenesis by inhibiting FGF2/FGFR1 pathway

Although VEGF-B was discovered as a VEGF-A homolog a long time ago,the angiogenic effect of VEGF-B remains poorly understood with limited and diverse findings from different groups.Notwithstanding,drugs that inhibit VEGF-B together with other VEGF family members are being used to treat patients with various neovascular diseases.It is therefore critical to have a better understanding of the angiogenic effect of VEGF-B and the underlying mechanisms.Using comprehensive in vitro and in vivo methods and models,we reveal here for the first time an unexpected and surprising function of VEGF-B as an endogenous inhibitor of angiogenesis by inhibiting the FGF2/FGFR1 pathway when the latter is abundantly expressed.Mechanistically,we unveil that VEGF-B binds to FGFR1,induces FGFR1/VEGFR1 complex formation,and suppresses FGF2-induced Erk activation,and inhibits FGF2-driven angiogenesis and tumor growth.Our work uncovers a previously unrecognized novel function of VEGF-B in tethering the FGF2/FGFR1 pathway.Given the anti-angiogenic nature of VEGF-B under conditions of high FGF2/FGFR1 levels,caution is warranted when modulating VEGF-B activity to treat neovascular diseases.

Underwater Monitoring Networks Based on Cable-Structured Triboelectric Nanogenerators

The importance ofocean exploration and underwater monitoring is becoming vital,due to the abundant biological,mineral energy,and other resources in the ocean.Here,a self-powered underwater cable-based triboelectric nanogenerator(TENG)is demonstrated for underwater monitoring of mechanical motion/triggering as wllas searching and rescuing inthe sea.Using a novel double-layer winding method combined with ferroelectric polarization,a self-powered cable-structured sensor with a stable electrical output has been manufactured,which can accurately respond to a variety of external mechanical stimuli.A self-powered cable sensing network woven using smart cables can comprehensively transmit information,such as the plane osition anddivedhofasumersbeMorereiely,can analyzeitsdrtionfmovemnt,seedand pathaong w transmiting information such as the submersible's size and momentum.The developed self-powered sensor based on the cable-based TENG not only has low cost and simple structure but also exhibits working accuracy and stability.Finally,the proposed work provides new ideas for future seabed exploration and ocean monitoring.

TCNQ-based organic cocrystal integrated red emission and n-type charge transport

Simultaneously realizing the optical and electrical properties of organic materials is always challenging.Herein,a convenient and promising strategy for designing organic materials with integrated optoelectronic properties based on cocrystal engineering has been put forward.By selecting the fluorene(Flu)and the 7,7′,8,8′-tetracyanoquinodimethane(TCNQ)as functional constituents,the Flu-TCNQ cocrystal prepared shows deep red emission at 702 nm,which is comparable to the commercialized red quantum dot.The highest electron mobility of organic field-effect transistor(OFET)based on Flu-TCNQ is 0.32 cm^(2)V^(−1)s^(−1).Spectroscopic analysis indicates that the intermolecular driving force contributing to the co-assembly of Flu-TCNQ is mainly charge transfer(CT)interaction,which leads to its different optoelectronic properties from constituents.