Based on first-principles calculation framework,the surface model,anodic dissolution,cathodic oxygen absorption reaction,and other related electrochemical corrosion models of Fe-Ce system were constructed,and the infl...Based on first-principles calculation framework,the surface model,anodic dissolution,cathodic oxygen absorption reaction,and other related electrochemical corrosion models of Fe-Ce system were constructed,and the influencing mechanism Ce doping on the corrosion resistance of Fe-Ce system in the Cl medium environment was analyzed.The results show that Ce doping on the first surface and subsurface inhibits the ionization of Fe atoms and greatly promotes the repassivation process of Fe matrix.Ce doping on the first layer is conducive to preventing the detachment of surface Fe atoms from Fe matrix and delaying the occurrence of corrosion.Ce atoms in the subsurface effectively increase the difficulty of Fe atoms detaching from the matrix at high Cl concentrations.When O diffusion is the controlling link of oxygen absorption reaction,Ce doping has no effects on the reaction rate of cathodic oxygen absorption.Ce doping enhances the electrochemical stability of Fe(100)1and reduces the anodic dissolution rate of Fe matrix,thereby improving its corrosion resistance.展开更多
The influence of the growth of rare earth on the viscosity during the uniform cooling of CaO-SiO_(2-)CaF_(2)-Ce_(2)O_(3)slag was investigated by the high temperature viscometer.The results show that Ce_(2)O_(3)affects...The influence of the growth of rare earth on the viscosity during the uniform cooling of CaO-SiO_(2-)CaF_(2)-Ce_(2)O_(3)slag was investigated by the high temperature viscometer.The results show that Ce_(2)O_(3)affects the viscosity variedly before and after the break temperature.At higher temperatures Ce_(2)O_(3)reduces the viscosity.When the temperature is below the break temperature,at a Ce_(2)O_(3)content of≥3 mol%,a rareearth crystalline phase is observed during the slag cooling process,and the break temperature progressively increases with the increase of Ce_(2)O_(3)concentration.There are no crystallized rare earths in the slag under the condition of Ce_(2)O_(3)concentration lower than 3 mol%.Too low or too high CaF_(2)content is found to be unfavorable for rare-earth crystallisation.The increase of Ce_(2)O_(3)content facilitates the depolymerization of silica-oxygen tetrahedral structure.Ca-F bond exists between structural units,weakening the flow resistance of structural units and lowering the viscosity of slag.展开更多
To provide insights into deforming Ce-O-S-Al inclusions in steels and improving the mechanical properties,the evolution process of such harmful inclusions in clean steels was investigated by thermodynamic calculation,...To provide insights into deforming Ce-O-S-Al inclusions in steels and improving the mechanical properties,the evolution process of such harmful inclusions in clean steels was investigated by thermodynamic calculation,metallographic examination and first-principles calculation in this paper.For the tested IF steel,the thermodynamic analysis results are consistent with the calculated formation enthalpy.After Ce addition,the inclusions are transformed from Al_(2)O_(3)and TiN-Al_(2)TiO_(5)-Al_(2)O_(3)to Ce2O_(3),Ce_(2)O_(2)S,CeAlO_(3),TiN-Al_(2)TiO_(5)-Ce_(2)O_(3)and TiN-Al_(2)TiO_(5)-Ce_(2)O_(2)S composite inclusions,which can be confirmed by metallographic examination.The elastic constants were calculated,and the bulk modulus,Young's modulus,shear modulus and Poisson's ratio were evaluated by the Voigt-Reuss-Hill(VRH)approximation.All inclusions except Ce_(2)O_(3)show apparent brittleness.TiN,Al_(2)O_(3),Al_(2)TiO_(5)and CeAlO_(3)present much higher hardness than iron matrix,while the hardness of Ce2O_(3)or Ce_(2)O_(2)S is close to that of iron matrix.The thermal expansion coefficients of Ce_(2)O_(3)and CeAlO_(3)are close to that of iron matrix,whereas,Ce_(2)O_(2)S inclusion has largely different thermal expansion coefficient from iron matrix and may deteriorate the steel performance at higher temperatures.The relatively small differences between Ce inclusions and iron matrix in terms of hardness,toughness,brittleness,and thermal expansion coefficient can explain the improvement of the mechanical properties of the tested steel.展开更多
In this paper,the origin mechanism of pitting corrosion induced by Ce_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) inclusions in a microalloyed steel was investigated by field emission scanning electron microscopy with energy ...In this paper,the origin mechanism of pitting corrosion induced by Ce_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) inclusions in a microalloyed steel was investigated by field emission scanning electron microscopy with energy dispersive spectroscopy and electron backscattered diffraction,conductivity atomic force microscopy,immersion test,and first-principles calculation.The results show that the Ce_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) inclusions are non-conductive,which are impossible to form corrosion couples with the steel matrix.There are no obvious lattice distortion zones in the steel matrix around the Ce_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) inclusions,so it is difficult to form micro-galvanic corrosion near the Ce inclusion.The order of work functions of the Ce inclusions and the steel matrix from small to large is Ce_(2)O_(2)S<Ce_(2)O_(3)<CeAlO_(3)<steel matrix,which is consistent with their dissolution sequence in the immersion test in _(3).5 wt%NaCl solution.Consequently,it is effective and reliable to use work function to predict or judge the dissolution behaviors of the Ce inclusions or steel matrix in corrosive solution.The Ce_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) inclusions have the tendency of self-dissolution and dissolve preferentially to the steel matrix in the solution by the salt effect,which lead to pitting corrosion of Ce-containing microalloyed steel.展开更多
The accurately determining the lake ^14C reservoir age has a crucial significance for climatic reconstruction. In this study, the optically stimulated luminescence （OSL） dating method is employed to date samples fro...The accurately determining the lake ^14C reservoir age has a crucial significance for climatic reconstruction. In this study, the optically stimulated luminescence （OSL） dating method is employed to date samples from highstand lacustrine sediments, palaeoshoreline, fluvial terrace, and the alluvial fan of the Heihai Lake catchment. Accelerator mass spectrometry （AMS） 14C dating was also used to date fossil plants from highstand lacustrine sediments. Based on the calculations of linear regression with OSL against radiocarbon ages for same layers of two sections, the quantitative ^14C reservoir ages were estimated to lie between 3 353 and 3 464 yr during the 1.8 to 2.4 ka, which showed temporal variation. The sources of old carbon are the dissolution of carbonate bedrocks distributed along the Kunlun Mountain. The OSL ages of the different members of the hydatogen sedimentary system at Heihai Lake catchment indicate that a stronger hydrologic condition occurred from 3.0±0.2 to 1.8±0.2 ka, with a maximum lake level of 9 m higher than present. This humid stage was widely recorded in different sediments on the QTP and Chinese Loess Plateau （CLP）, indicating its broad synchronicity across the Asian Summer Monsoon region. The enhanced East Asian Summer Monsoon （EASM） and the Indian Summer Monsoon （ISM） resulted in the increase of moisture availability for the Heihai Lake area during this stage.展开更多
Total organic carbon（TOC） in lake sediments and its stable carbon isotope（δ（13）C（org）） are widely applied to investigate paleoenvironmental changes even though their implications are complicated and multi-exp...Total organic carbon（TOC） in lake sediments and its stable carbon isotope（δ（13）C（org）） are widely applied to investigate paleoenvironmental changes even though their implications are complicated and multi-explanatory. Organic geochemistry studies of lake sediments from Qinghai Lake have been investigated, but some interpretations are controversial. In this study, TOC of one Holocene eolian section and δ（13）C（org） of three eolian sections were studied around Qinghai Lake. Results indicate that the TOC content in eolian deposits was low during the Early Holocene, and gradually increased to high values during the Middle and Late Holocene. The variation in TOC content of eolian deposits is different from that in the lacustrine sequence from Qinghai Lake during the Holocene. The δ（13）C（org） values in the eolian sections were relatively stable, with oscillation amplitudes of 4‰（ranging from-25.8‰ to-22.1‰）, in contrast to 10‰ variation s in δ（13）C（org） values（varying from-30‰ to-20‰） in lacustrine sediments. Through comparison of TOC and δ（13）C（org） values between eolian deposits and lacustrine sediments, we can confirm indications that the organic matter in Qinghai Lake sediments during the Holocene was primarily a contribution of the aquatic species in the lake. This is significant for understanding the origin of organic matter in lake sediments on the northeastern Qinghai-Tibetan Plateau and for paleoenvironmental inferences using such proxies.展开更多
Biomass is the most bountiful renewable carbon resource on earth.Photocatalytic transformation is a promising method to utilize biomass to obtain high-value-added chemicals and it has more obvious advantages compared ...Biomass is the most bountiful renewable carbon resource on earth.Photocatalytic transformation is a promising method to utilize biomass to obtain high-value-added chemicals and it has more obvious advantages compared with thermochemical and biological processes due to the milder operational conditions,fewer reagents and equipment.Semiconductor material is one of the most common kinds of heterogeneous biomass photocatalysts,which has the advantages of high selectivity,stable catalytic performance,long activation time,and low cost.In this paper,the significant research progress on the photocatalytic transformation of biomass with semiconductor materials to produce high-value-added chemicals is reviewed,and the three most typical semiconductor photocatalysts(TiO_(2),Cd S,and g-C_(3)N_(4))are detailed.The photocatalytic mechanism and photocatalytic system optimization including structural modification,metal co-catalyst loading,and introduction of heterojunction are presented.Besides,the main problems,the development direction and trend of semiconductor materials in photocatalytic transformations of biomass in the future are prospected,which provide guidance and inspiration for the further development of semiconductor photocatalysts and make contributions to the progress in efficient utilization of biomass.展开更多
Beyond graphene, the layered transition metal dichalcogenides （TMDs） have gained considerable attention due to their unique properties. Herein, we review the lattice dynamic and thermal properties of monolayer TMDs,...Beyond graphene, the layered transition metal dichalcogenides （TMDs） have gained considerable attention due to their unique properties. Herein, we review the lattice dynamic and thermal properties of monolayer TMDs, including their phonon dispersion, relaxation time, mean free path （MFP）, and thermal conductivities. In particular, the experimental and theoretical studies reveal that the TMDs have relatively low thermal conductivities due to the short phonon group velocity and MFP, which poses a significant challenge for efficient thermal management of TMDs-based devices. Importantly, recent studies have shown that this issue could be largely addressed by connecting TMDs and other materials （such as metal electrode and graphene） with chemical bonds, and a relatively high interracial thermal conductance （ITC） could be achieved at the covalent bonded interface. The ITC of MoS2/Au interface with chemical edge contact is more than 10 times higher than that with physical side contact. In this article, we review recent advances in the study of TMD-related ITC. The effects of temperature, interfacial vacancy, contact orientation, and phonon modes on the edge-contacted interface are briefly discussed.展开更多
To determine the acoustic wave propagation characteristics of bedded shales under different confining pressures and temperatures,shales from the Longmaxi Formation in the Sichuan Basin are taken as research objects.Ba...To determine the acoustic wave propagation characteristics of bedded shales under different confining pressures and temperatures,shales from the Longmaxi Formation in the Sichuan Basin are taken as research objects.Based on ultrasonic experiments,the acoustic wave prop-agation properties of shales with different bedding angles are investigated.The effects of the confining pressure,temperature,and bedding angle on the acoustic velocity,attenuation coefficient,and acoustic anisotropy coefficient are analyzed.Based on the results,an acoustic velocity prediction model for bedded shales considering the confining pressure,temperature,and bedding angle is established.The experiments show that,for confining pressures from 0 to 50 MPa and temperatures from 20 to 100 ℃,the acoustic velocity of the shales increases with increasing confining pressure and decreases with increasing temperature and bedding angle.The attenuation coefficient of the shales exhibits a decreasing trend with increasing confining pressure,but increases with increasing temperature and bedding angle.The acoustic anisotropy coefficient of shale gradually decreases with increasing confining pressure,but increases with increasing temperature and bedding angle.The acoustic velocity prediction model for in-situ bedded shales established in this study has a high level of accuracy.The relationship between the acoustic anisotropy coefficient and the bedding angle is satisfied by a binomial equation.The relationship between the acoustic anisotropy coefficient and the confining pressure and temperature follows a binary linear logarithmic equation.展开更多
To address the pressing global need for carbon-neutral fuels,optimizing the conversion of biomass to biooil(bio-chemicals)is crucial.Here,we introduce MXene(Ti_(3)C_(2)T_(x))as an innovative catalyst in biomass pyroly...To address the pressing global need for carbon-neutral fuels,optimizing the conversion of biomass to biooil(bio-chemicals)is crucial.Here,we introduce MXene(Ti_(3)C_(2)T_(x))as an innovative catalyst in biomass pyrolysis,exhibiting significant prowess in boosting levoglucosan yields.Py-GC/MS analysis indicated a remarkable 438%enhancement in levoglucosan yield when a 5 wt%catalyst-to-biomass ratio was employed.Laboratory-scale studies achieved an impressive 13.95 wt%levoglucosan in ex-situ fixed-bed catalytic pyrolysis,a yield that is 19.6 times higher than that from pure biomass at 40 wt%catalyst loading.Recycling evaluations affirm the robust stability of the MXene catalyst,validating its potential for multiple use cycles in eco-friendly industrial levoglucosan production.展开更多
A simulation method of dense particle-gas two-phase flow has been developed. The binding force is introduced to present the impact of particle clustering and its expression is deduced according to the principle of min...A simulation method of dense particle-gas two-phase flow has been developed. The binding force is introduced to present the impact of particle clustering and its expression is deduced according to the principle of minimal potential energy. The cluster collision, break-up and coalescence models are proposed based on the assumption that the particle cluster are treated as one discrete phase. These models are used to numerically study the two-phase flow field in a circulating fluidized bed （CFB）. Detailed results of the cluster structure, cluster size, particle volume fraction, gas velocity, and particle velocity are obtained. The correlation between the simulation results and experimental data justifies that these models and algorithm are reasonable, and can be used to efficiently study the dense particle-gas two-phase flow.展开更多
The Power Integrated Automation System has a large amount of the real-time data, it needs to achieve data sharing in different modules in its own system, sometimes even needs to be shared with the other systems. The t...The Power Integrated Automation System has a large amount of the real-time data, it needs to achieve data sharing in different modules in its own system, sometimes even needs to be shared with the other systems. The thesis discusses the characteristics and the ways of the real-time data sharing in the first place. Then, it compares the merits and drawbacks in different ways. Besides, it gives a viable resolution in different aspects, such as the design of the real-time database, the framework of the communication system and the design of the communication software, as well as the real-time data sharing in different systems.展开更多
To explore the effect of bedding and initial confining pressure on the energy evolution characteristics of shale during the unloading process,samples were drilled with different bedding angles,unloading tests were con...To explore the effect of bedding and initial confining pressure on the energy evolution characteristics of shale during the unloading process,samples were drilled with different bedding angles,unloading tests were conducted under different initial confining pressures,and the me-chanical and energy evolution characteristics of shale during the unloading process were analyzed.The results show that the stressestrain curve of the unloading test can be divided into the linear elasticity stage,the stable crack growth stage,the accelerated crack growth stage,and the post-failure stage.Critical confining pressure can show the relative strength of the rock samples.The elastic modulus and Poisson's ratio increase with an increase in axial preset load.The elastic modulus increases with the bedding angle,and the effect of the bedding angle on the Poisson's ratio is insignificant.The energy evolution of the unloading test can be divided into three stages:energy accumulation,energy dissipation,and energy release.The larger the axial preset load,the higher the critical confining pressure,the higher the elastic modulus,and the higher the Poisson's ratio.The total energy,elastic energy,and dissipation energy all increase with the increase in the initial confining pressure,and the correlation is high.Confining pressure enhances the ability of the shale sample to store elastic energy and improves the ability of the shale sample to resist internal crack propagation.The total energy,elastic energy,and dissipated energy of the samples in the failure point decrease first and then increase with the increase in the bedding angle.The maximum value can be obtained when the bedding angle is 0°.The elastic energy and dissipated energy of shale are highly heterogeneous due to bedding,and the effects of bedding should be taken into account when exploring the law of rock deformation and failure from an energy perspective.展开更多
To explore the influences of gravel characteristics on hydraulic fracture propagation in conglomerate formations, the real rock fracture process analysis software was used under specific stress conditions: including g...To explore the influences of gravel characteristics on hydraulic fracture propagation in conglomerate formations, the real rock fracture process analysis software was used under specific stress conditions: including gravel particle size, gravel volume content, and gravel strength. Based on the numerical simulation results, the fracture propagation process under different conditions was investigated and the type and evolution of fractures were described. The results showed that larger gravel particle sizes led to stronger shielding and induction effects on the fractures. With the increasing gravel particle size, the propagation model of the fractures changes gradually from by passing gravel to passing through gravel or embedding in gravel particles. When the gravel particle sizes are constant, with increasing gravel volume content, the conglomerate reservoir becomes more heterogeneous and the fractures become more easily shielded and inducted by the gravel particles. Therefore, the fractures become more dispersed and the fracture propagation laws become more complex, which allows the formation of a hydraulic fracture network. The greater the difference in the ratio of the strength parameters of the gravel to the strength parameters of the matrix, the more strongly the fractures are blocked by the gravels and the propagation model of fractures changes from passing through gravel to by passing gravel.展开更多
Radiative cooling utilizes the ultracold(∼3 K)deep space to cool terrestrial objects at no cost to active energy consumption.It finds widespread applica-tions across various fields and paves a promising strategy for ...Radiative cooling utilizes the ultracold(∼3 K)deep space to cool terrestrial objects at no cost to active energy consumption.It finds widespread applica-tions across various fields and paves a promising strategy for tackling global energy and environmental issues,such as scorching and freshwater short-ages.However,a comprehensive review of the applications,efficacy,and future of radiative cooling technologies has not been reported.展开更多
Importance:Medulloblastoma(MB)is the most common malignant brain tumor in children,with metastasis being the primary cause of recurrence and mortality.The tumor microenvironment(TME)plays a critical role in driving me...Importance:Medulloblastoma(MB)is the most common malignant brain tumor in children,with metastasis being the primary cause of recurrence and mortality.The tumor microenvironment(TME)plays a critical role in driving metastasis;however,the mechanisms underlying TME alterations in MB metastasis remain poorly understood.Objective:To develop and validate machine learning(ML)models for predicting patient outcomes in MB and to investigate the role of TME components,particularly immune cells and immunoregulatory molecules,in metastasis.Methods:ML models were constructed and validated to predict prognosis and metastasis in MB patients.Eight algorithms were evaluated,and the optimal model was selected.Lasso regression was employed for feature selection,and SHapley Additive exPlanations values were used to interpret the contribution of individual features to model predictions.Immune cell infiltration in tumor tissues was quantified using the microenvironment cell populations-counter method,and immunohistochemistry was applied to analyze the expression and distribution of specific proteins in tumor tissues.Results:The ML models identified metastasis as the strongest predictor of poor prognosis in MB patients,with significantly worse survival outcomes observed in metastatic cases.High infiltration of CD8+T cells and cytotoxic T lymphocytes(CTLs),along with elevated expression of the TGFB1 gene encoding transforming growth factor beta 1(TGF-β1),were strongly associated with metastasis.Independent transcriptomic and immunohistochemical analyses confirmed significantly higher CD8+T cell/CTL infiltration and TGF-β1 expression in metastatic compared to nonmetastatic MB samples.Patients with both high CD8+T cell/CTL infiltration and elevated TGFB1 expression in the context of metastasis exhibited significantly worse survival outcomes compared to patients with low expression and no metastasis.Interpretation:This study identifies metastasis as the key prognostic factor in MB and reveals the pivotal roles of CD8+T cells,CTLs,and TGF-β1 within the TME in promoting metastasis and poor outcomes.These findings provide a foundation for developing future therapeutic strategies targeting the TME to improve MB patient outcomes.展开更多
As the"Asian Water Tower"and the source of many major rivers in Asia,the Tibetan Plateau(TP)significantly affects human societies in densely-populated Asia[1].Lakes in the TP have a total area of^5×10^4...As the"Asian Water Tower"and the source of many major rivers in Asia,the Tibetan Plateau(TP)significantly affects human societies in densely-populated Asia[1].Lakes in the TP have a total area of^5×10^4 km^2 and hence they comprise an important component of the"Asian Water Tower".These lakes are sensitive to climate changes and have exhibited an overall trend of rapid expansion during recent decades[2].展开更多
The mode-I fracture toughness is of great significance for evaluating the fracturing ability of shale reservoirs.In this study,the mode-I fracture toughness of the shale in the Lower Silurian Longmaxi Formation,Southe...The mode-I fracture toughness is of great significance for evaluating the fracturing ability of shale reservoirs.In this study,the mode-I fracture toughness of the shale in the Lower Silurian Longmaxi Formation,Southern Sichuan Basin was determined with the Cracked Chevron Notched Brazilian Disc(CCNBD).Based on the experimental data,the relationships among the mode-I fracture toughness,the density,the acoustic time and the clay mineral content were analyzed.The shale samples for fracture toughness test from cores were commonly limited,the investigation of fracture toughness using well logs was necessary.Therefore,a prediction model was proposed by correlating the fracture toughness with well logs responses.The results indicate that the fracture toughness of shale samples is from 0.4744 MPa$m1/2 to 1.0607 MPa$m1/2 with an average of 0.7817 MPa$m1/2,indicating that the anisotropy of fracture toughness of the Longmaxi Formation shale.The clay mineral content and the density have a positive effect on the fracture toughness,whereas the acoustic time plays a negative role on the fracture toughness.The clay mineral content has an important effect on the relationships among fracture toughness,acoustic time and density.The prediction model can provide continuous data of mode-I fracture toughness along the wellbore for field hydraulic fracturing operation,and it has certain guiding significance in the exploration and development of oil and gas reservoirs.展开更多
As a serious problem in drilling operation,wellbore instability restricts efficient development of shale gas.The interaction between the drilling fluid and shale with hydration swelling property would have impact on t...As a serious problem in drilling operation,wellbore instability restricts efficient development of shale gas.The interaction between the drilling fluid and shale with hydration swelling property would have impact on the generation and propagation mechanism of cracks in shale formation,leading to wellbore instability.In order to investigate the influence of the hydration swelling on the crack propagation,mineral components and physicochemical properties of shale from the Lower Silurian Longmaxi Formation(LF)were investigated by using the XRD analysis,cation exchange capabilities(CEC)analysis,and SEM observation,and we researched the hydration mechanism of LF shale.Results show that quartz and clay mineral are dominated in mineral composition,and illite content averaged 67%in clay mineral.Meanwhile,CEC of the LF shale are 94.4 mmol/kg.The process of water intruding inside shale along microcracks was able to be observed through high power microscope,meanwhile,the hydration swelling stress would concentrate at the crack tip.The microcracks would propagate,bifurcate and connect with each other,with increase of water immersing time,and it would ultimately develop into macro-fracture.Moreover,the macrocracks extend and coalesce along the bedding,resulting in the rock failure into blocks.Hydration swelling is one of the major causes that lead to wellbore instability of the LF shale,and therefore improving sealing capacity and inhibition of drilling fluid system is an effective measure to stabilize a borehole.展开更多
In this paper,the pore structure characteristics of shale samples from the Lower Silurian Longmaxi Formation in South of Sichuan Basin of China were investigated by total organic carbon(TOC)content determination,X-ray...In this paper,the pore structure characteristics of shale samples from the Lower Silurian Longmaxi Formation in South of Sichuan Basin of China were investigated by total organic carbon(TOC)content determination,X-ray diffraction(XRD),scanning electron microscope(SEM),low pressure nitrogen adsorption(LPNA)and high pressure mercury injection(HPMI).The fractal dimension of shale samples was calculated based on Frenkel-Halsey-Hill(FHH)model and thermodynamic relation model.The results showed that the major mineral compositions of shales were quartz and clay content.Organic pores,intergranular pores,intragranular pores,microfractures were widely developed in the shale samples,of which organic pores were the most developed.The pore morphology was mainly ink bottle-shaped pores and slit-shaped pores;the pore size distribution of shale samples was complex with multiple distribution peaks,the pore size between 3 and 40 nm occupied the most of storage space.The fractal dimension Dn1 of pores between 2 nm and 10 nm was 2.7177e2.7933,while fractal dimension Dn2 of pores between 10 nm and 50 nm was 2.2439e2.5468.The fractal dimension Dr of macropores calculated by the thermodynamic model was 2.6401e2.7025.展开更多
基金Project supported by the National Natural Science Foundation of China(52364044,52204364)Scientific Research Special Project for First-Class Disciplines of Education Department of Inner Mongolia Autonomous Region(YLXKZX-NKD-001,YLXKZX-NKD-011)Basic Scientific Research Business Expenses of Colleges and Universities of Inner Mongolia Autonomous Region(2023QNJS011)。
文摘Based on first-principles calculation framework,the surface model,anodic dissolution,cathodic oxygen absorption reaction,and other related electrochemical corrosion models of Fe-Ce system were constructed,and the influencing mechanism Ce doping on the corrosion resistance of Fe-Ce system in the Cl medium environment was analyzed.The results show that Ce doping on the first surface and subsurface inhibits the ionization of Fe atoms and greatly promotes the repassivation process of Fe matrix.Ce doping on the first layer is conducive to preventing the detachment of surface Fe atoms from Fe matrix and delaying the occurrence of corrosion.Ce atoms in the subsurface effectively increase the difficulty of Fe atoms detaching from the matrix at high Cl concentrations.When O diffusion is the controlling link of oxygen absorption reaction,Ce doping has no effects on the reaction rate of cathodic oxygen absorption.Ce doping enhances the electrochemical stability of Fe(100)1and reduces the anodic dissolution rate of Fe matrix,thereby improving its corrosion resistance.
基金Project supported by the Inner Mongolia University of Science and Technology Basic Research Business Fee Project(2022QNJS068,2024QNJS132)Inner Mongolia Autonomous Region Scientific and Technological Achievements Transformation Project(CGZH2018153)+1 种基金Inner Mongolia Autonomous Region Science and Technology Innovation Guidance Incentive Fund(0406041703)Project of Natural Science Foundation of Inner Mongolia(2024SHZR2341)。
文摘The influence of the growth of rare earth on the viscosity during the uniform cooling of CaO-SiO_(2-)CaF_(2)-Ce_(2)O_(3)slag was investigated by the high temperature viscometer.The results show that Ce_(2)O_(3)affects the viscosity variedly before and after the break temperature.At higher temperatures Ce_(2)O_(3)reduces the viscosity.When the temperature is below the break temperature,at a Ce_(2)O_(3)content of≥3 mol%,a rareearth crystalline phase is observed during the slag cooling process,and the break temperature progressively increases with the increase of Ce_(2)O_(3)concentration.There are no crystallized rare earths in the slag under the condition of Ce_(2)O_(3)concentration lower than 3 mol%.Too low or too high CaF_(2)content is found to be unfavorable for rare-earth crystallisation.The increase of Ce_(2)O_(3)content facilitates the depolymerization of silica-oxygen tetrahedral structure.Ca-F bond exists between structural units,weakening the flow resistance of structural units and lowering the viscosity of slag.
基金Project supported by National Natural Science Foundation of China(51774190,51664044)Natural Science Foundation of Inner Mongolia,China(2018LH05005).
文摘To provide insights into deforming Ce-O-S-Al inclusions in steels and improving the mechanical properties,the evolution process of such harmful inclusions in clean steels was investigated by thermodynamic calculation,metallographic examination and first-principles calculation in this paper.For the tested IF steel,the thermodynamic analysis results are consistent with the calculated formation enthalpy.After Ce addition,the inclusions are transformed from Al_(2)O_(3)and TiN-Al_(2)TiO_(5)-Al_(2)O_(3)to Ce2O_(3),Ce_(2)O_(2)S,CeAlO_(3),TiN-Al_(2)TiO_(5)-Ce_(2)O_(3)and TiN-Al_(2)TiO_(5)-Ce_(2)O_(2)S composite inclusions,which can be confirmed by metallographic examination.The elastic constants were calculated,and the bulk modulus,Young's modulus,shear modulus and Poisson's ratio were evaluated by the Voigt-Reuss-Hill(VRH)approximation.All inclusions except Ce_(2)O_(3)show apparent brittleness.TiN,Al_(2)O_(3),Al_(2)TiO_(5)and CeAlO_(3)present much higher hardness than iron matrix,while the hardness of Ce2O_(3)or Ce_(2)O_(2)S is close to that of iron matrix.The thermal expansion coefficients of Ce_(2)O_(3)and CeAlO_(3)are close to that of iron matrix,whereas,Ce_(2)O_(2)S inclusion has largely different thermal expansion coefficient from iron matrix and may deteriorate the steel performance at higher temperatures.The relatively small differences between Ce inclusions and iron matrix in terms of hardness,toughness,brittleness,and thermal expansion coefficient can explain the improvement of the mechanical properties of the tested steel.
基金supported by the National Natural Science Foundation of China (51774190,51961032)China Postdoctoral Science Foundation(2021MD703850)Natural Science Foundation of Inner Mongolia,China(2020MS05072)。
文摘In this paper,the origin mechanism of pitting corrosion induced by Ce_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) inclusions in a microalloyed steel was investigated by field emission scanning electron microscopy with energy dispersive spectroscopy and electron backscattered diffraction,conductivity atomic force microscopy,immersion test,and first-principles calculation.The results show that the Ce_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) inclusions are non-conductive,which are impossible to form corrosion couples with the steel matrix.There are no obvious lattice distortion zones in the steel matrix around the Ce_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) inclusions,so it is difficult to form micro-galvanic corrosion near the Ce inclusion.The order of work functions of the Ce inclusions and the steel matrix from small to large is Ce_(2)O_(2)S<Ce_(2)O_(3)<CeAlO_(3)<steel matrix,which is consistent with their dissolution sequence in the immersion test in _(3).5 wt%NaCl solution.Consequently,it is effective and reliable to use work function to predict or judge the dissolution behaviors of the Ce inclusions or steel matrix in corrosive solution.The Ce_(2)O_(3),Ce_(2)O_(2)S,and CeAlO_(3) inclusions have the tendency of self-dissolution and dissolve preferentially to the steel matrix in the solution by the salt effect,which lead to pitting corrosion of Ce-containing microalloyed steel.
基金supported by the National Natural Science Foundation of China(No.41401008)West Light Foundation of the Chinese Academy of Sciences(No.Y412021005)+1 种基金Natural Science Foundation of Qinghai Province(No.2016-ZJ-926Q)the instrument function development program of the Chinese Academy of Sciences(No.Y410041013)
文摘The accurately determining the lake ^14C reservoir age has a crucial significance for climatic reconstruction. In this study, the optically stimulated luminescence （OSL） dating method is employed to date samples from highstand lacustrine sediments, palaeoshoreline, fluvial terrace, and the alluvial fan of the Heihai Lake catchment. Accelerator mass spectrometry （AMS） 14C dating was also used to date fossil plants from highstand lacustrine sediments. Based on the calculations of linear regression with OSL against radiocarbon ages for same layers of two sections, the quantitative ^14C reservoir ages were estimated to lie between 3 353 and 3 464 yr during the 1.8 to 2.4 ka, which showed temporal variation. The sources of old carbon are the dissolution of carbonate bedrocks distributed along the Kunlun Mountain. The OSL ages of the different members of the hydatogen sedimentary system at Heihai Lake catchment indicate that a stronger hydrologic condition occurred from 3.0±0.2 to 1.8±0.2 ka, with a maximum lake level of 9 m higher than present. This humid stage was widely recorded in different sediments on the QTP and Chinese Loess Plateau （CLP）, indicating its broad synchronicity across the Asian Summer Monsoon region. The enhanced East Asian Summer Monsoon （EASM） and the Indian Summer Monsoon （ISM） resulted in the increase of moisture availability for the Heihai Lake area during this stage.
基金funded by Chinese Post-doctoral Research Fund (No. 2014T70951)the National Natural Science Foundation of China (Nos. 41201014, 41371028, 41402314)
文摘Total organic carbon（TOC） in lake sediments and its stable carbon isotope（δ（13）C（org）） are widely applied to investigate paleoenvironmental changes even though their implications are complicated and multi-explanatory. Organic geochemistry studies of lake sediments from Qinghai Lake have been investigated, but some interpretations are controversial. In this study, TOC of one Holocene eolian section and δ（13）C（org） of three eolian sections were studied around Qinghai Lake. Results indicate that the TOC content in eolian deposits was low during the Early Holocene, and gradually increased to high values during the Middle and Late Holocene. The variation in TOC content of eolian deposits is different from that in the lacustrine sequence from Qinghai Lake during the Holocene. The δ（13）C（org） values in the eolian sections were relatively stable, with oscillation amplitudes of 4‰（ranging from-25.8‰ to-22.1‰）, in contrast to 10‰ variation s in δ（13）C（org） values（varying from-30‰ to-20‰） in lacustrine sediments. Through comparison of TOC and δ（13）C（org） values between eolian deposits and lacustrine sediments, we can confirm indications that the organic matter in Qinghai Lake sediments during the Holocene was primarily a contribution of the aquatic species in the lake. This is significant for understanding the origin of organic matter in lake sediments on the northeastern Qinghai-Tibetan Plateau and for paleoenvironmental inferences using such proxies.
基金the financial supports provided by the National Natural Science Foundation of China(Nos.22108221 and 52203145)the Shaanxi Natural Science Foundation(No.2021JQ-028)。
文摘Biomass is the most bountiful renewable carbon resource on earth.Photocatalytic transformation is a promising method to utilize biomass to obtain high-value-added chemicals and it has more obvious advantages compared with thermochemical and biological processes due to the milder operational conditions,fewer reagents and equipment.Semiconductor material is one of the most common kinds of heterogeneous biomass photocatalysts,which has the advantages of high selectivity,stable catalytic performance,long activation time,and low cost.In this paper,the significant research progress on the photocatalytic transformation of biomass with semiconductor materials to produce high-value-added chemicals is reviewed,and the three most typical semiconductor photocatalysts(TiO_(2),Cd S,and g-C_(3)N_(4))are detailed.The photocatalytic mechanism and photocatalytic system optimization including structural modification,metal co-catalyst loading,and introduction of heterojunction are presented.Besides,the main problems,the development direction and trend of semiconductor materials in photocatalytic transformations of biomass in the future are prospected,which provide guidance and inspiration for the further development of semiconductor photocatalysts and make contributions to the progress in efficient utilization of biomass.
基金financial support by the Agency for Science, Technology and Research (A*STAR), Singaporethe use of computing resources at the A*STAR Computational Resource Centre, Singaporesupported in part by the Science and Engineering Research Council (152-70-00017)
文摘Beyond graphene, the layered transition metal dichalcogenides （TMDs） have gained considerable attention due to their unique properties. Herein, we review the lattice dynamic and thermal properties of monolayer TMDs, including their phonon dispersion, relaxation time, mean free path （MFP）, and thermal conductivities. In particular, the experimental and theoretical studies reveal that the TMDs have relatively low thermal conductivities due to the short phonon group velocity and MFP, which poses a significant challenge for efficient thermal management of TMDs-based devices. Importantly, recent studies have shown that this issue could be largely addressed by connecting TMDs and other materials （such as metal electrode and graphene） with chemical bonds, and a relatively high interracial thermal conductance （ITC） could be achieved at the covalent bonded interface. The ITC of MoS2/Au interface with chemical edge contact is more than 10 times higher than that with physical side contact. In this article, we review recent advances in the study of TMD-related ITC. The effects of temperature, interfacial vacancy, contact orientation, and phonon modes on the edge-contacted interface are briefly discussed.
基金funded by the National Natural Sci-ence Foundation of China(42272190)the Sichuan Provincial Natural Science Foundation of China(2022NSFSC1065)the National College Student Innovation and Entrepreneurship Training Program(202210615030).
文摘To determine the acoustic wave propagation characteristics of bedded shales under different confining pressures and temperatures,shales from the Longmaxi Formation in the Sichuan Basin are taken as research objects.Based on ultrasonic experiments,the acoustic wave prop-agation properties of shales with different bedding angles are investigated.The effects of the confining pressure,temperature,and bedding angle on the acoustic velocity,attenuation coefficient,and acoustic anisotropy coefficient are analyzed.Based on the results,an acoustic velocity prediction model for bedded shales considering the confining pressure,temperature,and bedding angle is established.The experiments show that,for confining pressures from 0 to 50 MPa and temperatures from 20 to 100 ℃,the acoustic velocity of the shales increases with increasing confining pressure and decreases with increasing temperature and bedding angle.The attenuation coefficient of the shales exhibits a decreasing trend with increasing confining pressure,but increases with increasing temperature and bedding angle.The acoustic anisotropy coefficient of shale gradually decreases with increasing confining pressure,but increases with increasing temperature and bedding angle.The acoustic velocity prediction model for in-situ bedded shales established in this study has a high level of accuracy.The relationship between the acoustic anisotropy coefficient and the bedding angle is satisfied by a binomial equation.The relationship between the acoustic anisotropy coefficient and the confining pressure and temperature follows a binary linear logarithmic equation.
基金financial support provided by the National Natural Science Foundation of China(Nos.22108221 and 52203145)。
文摘To address the pressing global need for carbon-neutral fuels,optimizing the conversion of biomass to biooil(bio-chemicals)is crucial.Here,we introduce MXene(Ti_(3)C_(2)T_(x))as an innovative catalyst in biomass pyrolysis,exhibiting significant prowess in boosting levoglucosan yields.Py-GC/MS analysis indicated a remarkable 438%enhancement in levoglucosan yield when a 5 wt%catalyst-to-biomass ratio was employed.Laboratory-scale studies achieved an impressive 13.95 wt%levoglucosan in ex-situ fixed-bed catalytic pyrolysis,a yield that is 19.6 times higher than that from pure biomass at 40 wt%catalyst loading.Recycling evaluations affirm the robust stability of the MXene catalyst,validating its potential for multiple use cycles in eco-friendly industrial levoglucosan production.
基金This work was financially supported by the National Natural Science Foundation of China (No.50406025).
文摘A simulation method of dense particle-gas two-phase flow has been developed. The binding force is introduced to present the impact of particle clustering and its expression is deduced according to the principle of minimal potential energy. The cluster collision, break-up and coalescence models are proposed based on the assumption that the particle cluster are treated as one discrete phase. These models are used to numerically study the two-phase flow field in a circulating fluidized bed （CFB）. Detailed results of the cluster structure, cluster size, particle volume fraction, gas velocity, and particle velocity are obtained. The correlation between the simulation results and experimental data justifies that these models and algorithm are reasonable, and can be used to efficiently study the dense particle-gas two-phase flow.
文摘The Power Integrated Automation System has a large amount of the real-time data, it needs to achieve data sharing in different modules in its own system, sometimes even needs to be shared with the other systems. The thesis discusses the characteristics and the ways of the real-time data sharing in the first place. Then, it compares the merits and drawbacks in different ways. Besides, it gives a viable resolution in different aspects, such as the design of the real-time database, the framework of the communication system and the design of the communication software, as well as the real-time data sharing in different systems.
基金supported by the Provincial Geological Exploration Projects in Guizhou Province(Grant Nos.52000024P0048BH10174 M)National Natural Science Foundation of China(Grant Nos.U1262209).
文摘To explore the effect of bedding and initial confining pressure on the energy evolution characteristics of shale during the unloading process,samples were drilled with different bedding angles,unloading tests were conducted under different initial confining pressures,and the me-chanical and energy evolution characteristics of shale during the unloading process were analyzed.The results show that the stressestrain curve of the unloading test can be divided into the linear elasticity stage,the stable crack growth stage,the accelerated crack growth stage,and the post-failure stage.Critical confining pressure can show the relative strength of the rock samples.The elastic modulus and Poisson's ratio increase with an increase in axial preset load.The elastic modulus increases with the bedding angle,and the effect of the bedding angle on the Poisson's ratio is insignificant.The energy evolution of the unloading test can be divided into three stages:energy accumulation,energy dissipation,and energy release.The larger the axial preset load,the higher the critical confining pressure,the higher the elastic modulus,and the higher the Poisson's ratio.The total energy,elastic energy,and dissipation energy all increase with the increase in the initial confining pressure,and the correlation is high.Confining pressure enhances the ability of the shale sample to store elastic energy and improves the ability of the shale sample to resist internal crack propagation.The total energy,elastic energy,and dissipated energy of the samples in the failure point decrease first and then increase with the increase in the bedding angle.The maximum value can be obtained when the bedding angle is 0°.The elastic energy and dissipated energy of shale are highly heterogeneous due to bedding,and the effects of bedding should be taken into account when exploring the law of rock deformation and failure from an energy perspective.
基金supported by the Major National Science and Technology Project(Grant No.2017ZX05001-004)the Young Scientific and Technological Innovation Team of Rock Physics in Unconventional Strata of Southwest Petroleum University(No.2018CXTD13).
文摘To explore the influences of gravel characteristics on hydraulic fracture propagation in conglomerate formations, the real rock fracture process analysis software was used under specific stress conditions: including gravel particle size, gravel volume content, and gravel strength. Based on the numerical simulation results, the fracture propagation process under different conditions was investigated and the type and evolution of fractures were described. The results showed that larger gravel particle sizes led to stronger shielding and induction effects on the fractures. With the increasing gravel particle size, the propagation model of the fractures changes gradually from by passing gravel to passing through gravel or embedding in gravel particles. When the gravel particle sizes are constant, with increasing gravel volume content, the conglomerate reservoir becomes more heterogeneous and the fractures become more easily shielded and inducted by the gravel particles. Therefore, the fractures become more dispersed and the fracture propagation laws become more complex, which allows the formation of a hydraulic fracture network. The greater the difference in the ratio of the strength parameters of the gravel to the strength parameters of the matrix, the more strongly the fractures are blocked by the gravels and the propagation model of fractures changes from passing through gravel to by passing gravel.
基金supported by the Beijing Natural Science Foundation(F252071,2232037)the National Natural Science Foundation of China(51906014).
文摘Radiative cooling utilizes the ultracold(∼3 K)deep space to cool terrestrial objects at no cost to active energy consumption.It finds widespread applica-tions across various fields and paves a promising strategy for tackling global energy and environmental issues,such as scorching and freshwater short-ages.However,a comprehensive review of the applications,efficacy,and future of radiative cooling technologies has not been reported.
基金National Natural Science Foundation of China,Grant/Award Number:82101204Beijing Hospital’s Authority Clinical Medicine Development of Special Funding,Grant/Award Number:XMLX202144
文摘Importance:Medulloblastoma(MB)is the most common malignant brain tumor in children,with metastasis being the primary cause of recurrence and mortality.The tumor microenvironment(TME)plays a critical role in driving metastasis;however,the mechanisms underlying TME alterations in MB metastasis remain poorly understood.Objective:To develop and validate machine learning(ML)models for predicting patient outcomes in MB and to investigate the role of TME components,particularly immune cells and immunoregulatory molecules,in metastasis.Methods:ML models were constructed and validated to predict prognosis and metastasis in MB patients.Eight algorithms were evaluated,and the optimal model was selected.Lasso regression was employed for feature selection,and SHapley Additive exPlanations values were used to interpret the contribution of individual features to model predictions.Immune cell infiltration in tumor tissues was quantified using the microenvironment cell populations-counter method,and immunohistochemistry was applied to analyze the expression and distribution of specific proteins in tumor tissues.Results:The ML models identified metastasis as the strongest predictor of poor prognosis in MB patients,with significantly worse survival outcomes observed in metastatic cases.High infiltration of CD8+T cells and cytotoxic T lymphocytes(CTLs),along with elevated expression of the TGFB1 gene encoding transforming growth factor beta 1(TGF-β1),were strongly associated with metastasis.Independent transcriptomic and immunohistochemical analyses confirmed significantly higher CD8+T cell/CTL infiltration and TGF-β1 expression in metastatic compared to nonmetastatic MB samples.Patients with both high CD8+T cell/CTL infiltration and elevated TGFB1 expression in the context of metastasis exhibited significantly worse survival outcomes compared to patients with low expression and no metastasis.Interpretation:This study identifies metastasis as the key prognostic factor in MB and reveals the pivotal roles of CD8+T cells,CTLs,and TGF-β1 within the TME in promoting metastasis and poor outcomes.These findings provide a foundation for developing future therapeutic strategies targeting the TME to improve MB patient outcomes.
基金the Strategic Priority Research Program of Chinese Academy of Sciences(XDA20090000)the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0202,2019QZKK0601)。
文摘As the"Asian Water Tower"and the source of many major rivers in Asia,the Tibetan Plateau(TP)significantly affects human societies in densely-populated Asia[1].Lakes in the TP have a total area of^5×10^4 km^2 and hence they comprise an important component of the"Asian Water Tower".These lakes are sensitive to climate changes and have exhibited an overall trend of rapid expansion during recent decades[2].
基金by the National Science and Technology Major Project(Grant No.2019A-3307)the National Natural Science Foundation of China(Grant No.41872167)。
文摘The mode-I fracture toughness is of great significance for evaluating the fracturing ability of shale reservoirs.In this study,the mode-I fracture toughness of the shale in the Lower Silurian Longmaxi Formation,Southern Sichuan Basin was determined with the Cracked Chevron Notched Brazilian Disc(CCNBD).Based on the experimental data,the relationships among the mode-I fracture toughness,the density,the acoustic time and the clay mineral content were analyzed.The shale samples for fracture toughness test from cores were commonly limited,the investigation of fracture toughness using well logs was necessary.Therefore,a prediction model was proposed by correlating the fracture toughness with well logs responses.The results indicate that the fracture toughness of shale samples is from 0.4744 MPa$m1/2 to 1.0607 MPa$m1/2 with an average of 0.7817 MPa$m1/2,indicating that the anisotropy of fracture toughness of the Longmaxi Formation shale.The clay mineral content and the density have a positive effect on the fracture toughness,whereas the acoustic time plays a negative role on the fracture toughness.The clay mineral content has an important effect on the relationships among fracture toughness,acoustic time and density.The prediction model can provide continuous data of mode-I fracture toughness along the wellbore for field hydraulic fracturing operation,and it has certain guiding significance in the exploration and development of oil and gas reservoirs.
基金This research was supported by the United Fund Project of National Natural Science Foundation of China(Grant No.U1262209)the National Natural Science Foundation of China(NSFC)(Grant No.51274172).
文摘As a serious problem in drilling operation,wellbore instability restricts efficient development of shale gas.The interaction between the drilling fluid and shale with hydration swelling property would have impact on the generation and propagation mechanism of cracks in shale formation,leading to wellbore instability.In order to investigate the influence of the hydration swelling on the crack propagation,mineral components and physicochemical properties of shale from the Lower Silurian Longmaxi Formation(LF)were investigated by using the XRD analysis,cation exchange capabilities(CEC)analysis,and SEM observation,and we researched the hydration mechanism of LF shale.Results show that quartz and clay mineral are dominated in mineral composition,and illite content averaged 67%in clay mineral.Meanwhile,CEC of the LF shale are 94.4 mmol/kg.The process of water intruding inside shale along microcracks was able to be observed through high power microscope,meanwhile,the hydration swelling stress would concentrate at the crack tip.The microcracks would propagate,bifurcate and connect with each other,with increase of water immersing time,and it would ultimately develop into macro-fracture.Moreover,the macrocracks extend and coalesce along the bedding,resulting in the rock failure into blocks.Hydration swelling is one of the major causes that lead to wellbore instability of the LF shale,and therefore improving sealing capacity and inhibition of drilling fluid system is an effective measure to stabilize a borehole.
文摘In this paper,the pore structure characteristics of shale samples from the Lower Silurian Longmaxi Formation in South of Sichuan Basin of China were investigated by total organic carbon(TOC)content determination,X-ray diffraction(XRD),scanning electron microscope(SEM),low pressure nitrogen adsorption(LPNA)and high pressure mercury injection(HPMI).The fractal dimension of shale samples was calculated based on Frenkel-Halsey-Hill(FHH)model and thermodynamic relation model.The results showed that the major mineral compositions of shales were quartz and clay content.Organic pores,intergranular pores,intragranular pores,microfractures were widely developed in the shale samples,of which organic pores were the most developed.The pore morphology was mainly ink bottle-shaped pores and slit-shaped pores;the pore size distribution of shale samples was complex with multiple distribution peaks,the pore size between 3 and 40 nm occupied the most of storage space.The fractal dimension Dn1 of pores between 2 nm and 10 nm was 2.7177e2.7933,while fractal dimension Dn2 of pores between 10 nm and 50 nm was 2.2439e2.5468.The fractal dimension Dr of macropores calculated by the thermodynamic model was 2.6401e2.7025.
