Clay deposits typically exhibit significant degrees of heterogeneity and anisotropy in their strength and stiffness properties.Such non-monotonic responses can significantly impact the stability analysis and design of...Clay deposits typically exhibit significant degrees of heterogeneity and anisotropy in their strength and stiffness properties.Such non-monotonic responses can significantly impact the stability analysis and design of overlying shallow foundations.In this study,the undrained bearing capacity of shallow foundations resting on inhomogeneous and anisotropic clay layers subjected to oblique-eccentric combined loading is investigated through a comprehensive series of finite element limit analysis(FELA)based on the well-established lower-bound theorem and second-order cone programming(SOCP).The heterogeneity of normally consolidated(NC)clays is simulated by adopting a well-known general model of undrained shear strength increasing linearly with depth.In contrast,for overconsolidated(OC)clays,the variation of undrained shear strength with depth is considered to follow a bilinear trend.Furthermore,the inherent anisotropy is accounted for by adopting different values of undrained shear strength along different directions within the soil medium,employing an iterative-based algorithm.The results of numerical simulations are utilized to investigate the influences of natural soil heterogeneity and inherent anisotropy on the ultimate bearing capacity,failure envelope,and failure mechanism of shallow foundations subjected to the various combinations of vertical-horizontal(V-H)and vertical-moment(V-M)loads.展开更多
With a growing population, an increasing number of petrochemical facilities are built with larger capacity and more complexity, which pose a great risk to assets, community and environment. The value of inherently saf...With a growing population, an increasing number of petrochemical facilities are built with larger capacity and more complexity, which pose a great risk to assets, community and environment. The value of inherently safer design is recognized with time by all stakeholders, and an effective tool is needed to evaluate and compare inherent safety of alternative technologies. This study developed a safety index to evaluate existing technologies for their safety levels and guide inherently safer design. The Integrated Risk-based Safety Index(IRSI) was developed based on a comprehensive review of petrochemical processes, incident cases from Sinopec and US Chemical Safety Board, and existing safety index systems. The IRSI included all major hazards, including fire, explosion,toxic release, dust explosion, physical explosion, and runaway. Also, the integrated life cycle approach considered chemical hazards, equipment failure rates and safety measures in this risk-based index. Advanced modeling techniques, PHAST simulation and Neural Network, were used in the development of three novel sub-indices in the projects, fire, explosion and toxic release. The index system could be easily incorporated into a user friendly tool for the ease of application. A case study of hydrogen dioxide was conducted using the IRSI, which showed its capability for evaluating the safety level of process facilities.展开更多
A one-step procedure is developed to synthesize inherently chiral p-tert-butylcalix[4]azacrown 1 through etherification between p-tert-butylcalix[4]arene and compound 3, which can be amplifed to efficiently prepare mo...A one-step procedure is developed to synthesize inherently chiral p-tert-butylcalix[4]azacrown 1 through etherification between p-tert-butylcalix[4]arene and compound 3, which can be amplifed to efficiently prepare more inherently cbiral calix[4]arenes in ABHH substitution pattern.展开更多
Digraph-based causal models have been widely used to model the cause and effect behavior of process systems. Signed digraphs （SDG） capture the direction of the effect. It should be mentioned that there are loops in ...Digraph-based causal models have been widely used to model the cause and effect behavior of process systems. Signed digraphs （SDG） capture the direction of the effect. It should be mentioned that there are loops in SDG generated from chemical process. From the point of the inherent operability, the worst unsafe factor is the SDG having positive loops that means any disturbance occurring within the loop will propagate through the nodes one by one and are amplified gradually, so the system may lose control, which may lead to an accident. So finding the positive loops in a SDG and treating these unsafe factors in a proper manner can improve the inherent safety of a chemical process. This article proposed a method that can detect the above-mentioned unsafe factors in the proc- ess conceptual design stage automatically through the analysis of the SDG generated from the chemical process. A case study is illustrated to show the working of the algorithm, and then a complicated case from industry is studied to depict the effectiveness of the proposed algorithm.展开更多
Dibenzo[b,fi[1,5]diazocines are a class of eight-membered heterocycles,which exhibit unique rigid saddle-shaped structure and possess inherent chirality.In this study,we report a convenient and straightforward method ...Dibenzo[b,fi[1,5]diazocines are a class of eight-membered heterocycles,which exhibit unique rigid saddle-shaped structure and possess inherent chirality.In this study,we report a convenient and straightforward method for the catalytic enantioselective synthesis of these unique chiral molecules through chiral phosphoric acid-catalyzed dimerization of 2-acylbenzoisocyanates.Notably,the addition of corresponding 2-acylaniline as the co-catalyst significantly improved the efficiency of these reactions,and a simple phase separation operation resulted in products with excellent enantiopurity.Experimental studies were performed to elucidate the mechanism behind these reactions,leading to the proposal of a plausible reaction mechanism based on the study findings.展开更多
Erratum to Soil Ecol.Lett.Doi:10.1007/s42832-021-0089-z The original version of this article unfortunately contained a mistake.The Figure 7B legend for two of the found genera is missing.The online versin of the origi...Erratum to Soil Ecol.Lett.Doi:10.1007/s42832-021-0089-z The original version of this article unfortunately contained a mistake.The Figure 7B legend for two of the found genera is missing.The online versin of the original article can be found at https://doi.org/10.1007/s42832-021-0089-z.展开更多
A series of novel N,O-type chiral ligands derived from enantiopure inherently chiral calix[4]arenes containing quinolin-2-yl-methanol moiety in the cone or partialcone conformation have been synthe-sized and character...A series of novel N,O-type chiral ligands derived from enantiopure inherently chiral calix[4]arenes containing quinolin-2-yl-methanol moiety in the cone or partialcone conformation have been synthe-sized and characterized. Moreover,they have been applied to the catalytic asymmetric addition of diethylzinc to benzaldehyde,which represents the first example that the inherently chiral calixarene can be used as the chiral ligands for the catalytic asymmetric synthesis.展开更多
Through a modified inherent strain model based on the minimum residual stress and deformation,three building schemes with different building postures and support structures were evaluated by finite element analysis.Re...Through a modified inherent strain model based on the minimum residual stress and deformation,three building schemes with different building postures and support structures were evaluated by finite element analysis.Results demonstrate that according to the principle of reducing the overall height of the building and reducing the support structure with a large tilt angle from the building direction,the residual stress and deformation can be effectively reduced by proper design of building posture and support before laser powder bed melting.Moreover,without the data of thermophysical property variation of Ti-6Al-4V artificial knee implants with temperature,predicting the residual stress and deformation with acceptable accuracy and reduced time cost can be achieved by the inherent strain model.展开更多
Sodium alginate(SA)is generally considered highly hydrophilic due to two hydroxyl groups and a carboxylate group on each pyranose ring.However,SA will form a gel after dissolving in water for a certain period.The two ...Sodium alginate(SA)is generally considered highly hydrophilic due to two hydroxyl groups and a carboxylate group on each pyranose ring.However,SA will form a gel after dissolving in water for a certain period.The two properties of SA,hydrophilicity and gelation,seem to be paradoxical.In this study,to explore the mechanism behind these paradoxical properties,the single-chain behaviors of SA in various liquid environments have been investigated by using single-molecule force spectroscopy(SMFS).In nonpolar solvents such as nonane,SA exhibits its single-chain inherent elasticity consistent with the theoretical elasticity derived from quantum mechanical(QM)calculations.Notably,the experimental curve of SA obtained in water shows a long plateau in the low force region.Further research reveals that this phenomenon is driven by the hydrophobic effect.Additionally,SA shows greater rigidity than its inherent elasticity in the middle and high force regions due to electrostatic repulsion between carboxylate groups on adjacent sugar rings.Comparative single-molecule studies suggest that SA exhibits considerable hydrophobicity,offering new insights into the gelation process in water.展开更多
Large-scale and heavily jointed rocks have inherent planes of anisotropy and secondary structural planes,such as dominant joint sets and random fractures,which result in significant differences in their failure mechan...Large-scale and heavily jointed rocks have inherent planes of anisotropy and secondary structural planes,such as dominant joint sets and random fractures,which result in significant differences in their failure mechanism and deformation behavior compared to other rock types.To address this issue,inherent anisotropic rocks with large-scale and dense joints are considered to be composed of the rock matrix,inherent planes of anisotropy,and secondary structural planes.Then a new implicit continuum model called LayerDFN is developed based on the crack tensor and damage tensor theories to characterize the mechanical properties of inherent anisotropic rocks.Furthermore,the LayerDFN model is implemented in the FLAC3D software,and a series of numerical results for typical example problems is compared with those obtained from the 3DEC,the analytical solutions,similar classical models,laboratory uniaxial compression tests,and field rigid bearing plate tests.The results demonstrate that the LayerDFN model can effectively capture the anisotropic mechanical properties of inherent anisotropic rocks,and can quantitatively characterize the damaging effect of the secondary structural planes.Overall,the numerical method based on the LayerDFN model provides a comprehensive and reliable approach for describing and analyzing the behavior of inherent anisotropic rocks,which will provide valuable insights for engineering design and decision-making processes.展开更多
The mechanical properties of stratified rocks are closely related not only to the stress state but also to the inherent structural anisotropy,which can be represented by the occurrence of bedding planes.This research ...The mechanical properties of stratified rocks are closely related not only to the stress state but also to the inherent structural anisotropy,which can be represented by the occurrence of bedding planes.This research aims to enhance the understanding of the anisotropic deformation and failure behaviors of stratified rocks by proposing a novel coupled elastoplastic-damage constitutive model.In this constitutive model,a scalar anisotropic parameter(stress-structure mixed invariant)based on the Pietruszczak–Mroz anisotropic theory is incorporated into a nonlinear yield surface,which accounts for the combined effects of the stress state and bedding structure on the anisotropic strength behaviors of stratified rocks.A damage-driven function governs the expansion and contraction of the anisotropic yield surface in the pre-peak strain hardening and post-peak strain-softening regions.The strength and deformation characteristics under multiaxial stress conditions are represented by incorporating the Lode's angle into the yield and plastic potential functions.Numerical simulations are conducted to facilitate a comparison with the conventional and true triaxial compression test data for several stratified rocks.The simulation results demonstrate good agreement with the test data,validating the effectiveness of the proposed constitutive model.This study provides theoretical and technical support for addressing engineering challenges involving stratified rocks.展开更多
In the present article, we study the effect of inherent anisotropy, i.e., initial bedding angle of particles and associated voids on macroscopic mechanical behavior of granular materials, by numerical simulation of se...In the present article, we study the effect of inherent anisotropy, i.e., initial bedding angle of particles and associated voids on macroscopic mechanical behavior of granular materials, by numerical simulation of several biaxial compression tests using the discrete element method （DEM）. Particle shape is considered to be irregular convex-polygonal. The effect of inherent anisotropy is investigated by following the evolution of mobilized shear strength and volume change during loading. As experimental tests have already shown, numerical simulations also indicate that initial anisotropic condition has a great influence on the strength and deformational behavior of granular assemblies. Comparison of simulations with tests using oval particles, shows that angularity influences both the mobilized shear strength and the volume change regime, which originates from the interlocking resistance between particles.展开更多
Inherently chiral 6,7-diphenyldibenzo[e,g][1,4]diazocine(DDD)has been synthesized enantioselectively for the first time via chiral phosphoric acid(CPA)-catalyzed cyclocondensation of readily available[1,1′-biphenyl]-...Inherently chiral 6,7-diphenyldibenzo[e,g][1,4]diazocine(DDD)has been synthesized enantioselectively for the first time via chiral phosphoric acid(CPA)-catalyzed cyclocondensation of readily available[1,1′-biphenyl]-2,2′-diamine(1a)and benzil(2a)in 82%yield,with 98%ee under mild reaction conditions.The strategy could also be applied to racemic biaryl diamines through kinetic resolution.The unexpectedly high interconversion energy barriers between the enantiomers(ΔG=39.5 kcal/mol)and the chemical stability rendered DDD an ideal platform for developing new chiral ligands and catalysts.Unique inherently chiralDDD-based phosphoramidites,phosphoric acid,mono-and diphosphine ligands were prepared from optically pure diphenol derivative DDDOL as a common precursor.Preliminary asymmetric reactions catalyzed by Pd or Rh in the presence of newly developed ligands exhibited comparable or even better enantioselectivities than the corresponding BINOLor SPINOL-derived ligands.Density functional theory calculation revealed the origin of the enantioselectivity during the process.展开更多
Nowadays,the predominant source for approximately 90%of epoxy resin materials worldwide is the diglycidyl ether of bisphenol A(DGEBA).However,the increasing recognition of environmental concerns,such as global warming...Nowadays,the predominant source for approximately 90%of epoxy resin materials worldwide is the diglycidyl ether of bisphenol A(DGEBA).However,the increasing recognition of environmental concerns,such as global warming and the depletion of petroleum reserves,necessitates the exploration of alternative options,specifically bio-epoxy resin derived from sustainable resources.Nonetheless,the inadequate flame retardancy of bio-epoxy resin presents a notable drawback,limiting its applicability in high-risk environments.The objective of this review article is to provide a concise overview of the latest and upto-date advances in flame-retardant epoxy resins derived from sustainable sources.Firstly,the discussion encompasses inherently flame-retardant bio-based epoxy resins,considering both bio-based epoxy monomers and bio-based curing agents,focusing on their flame retardancy and mechanical properties.Furthermore,the utilization of phosphorus-containing and silicon-containing additives in bio-based epoxy is explored.Additionally,a comprehensive evaluation of partially bio-based intrinsically flame retardant epoxy resins is provided.Finally,this article offers an extensive survey of the current state-of-the-art in the field and presents future perspectives,serving as a valuable resource for researchers engaged in the study of flame-retardant epoxy resins derived from sustainable resources.展开更多
Compared to single atom catalysts(SACs),the introduction of dual atom catalysts(DACs)has a significantly positive effect on improving the efficiency in the electrocatalytic nitrogen reduction reaction(NRR)which provid...Compared to single atom catalysts(SACs),the introduction of dual atom catalysts(DACs)has a significantly positive effect on improving the efficiency in the electrocatalytic nitrogen reduction reaction(NRR)which provides an environmental alternative to the Haber-Bosch process.However,the research on the mechanism and strategy of designing bimetallic combinations for better performance is still in its early stages.Herein,based on"blocking and rebalance"mechanism,45 combinations of bimetallic pair dopedα-phosphorus carbide(TM_(A)TM_(B)@PC)are investigated as efficient NRR catalysts through density functional theory and machine learning method.After a multi-step screening,the combinations of TiV,TiFe,MnMo,and FeW exhibit highly efficient catalytic performance with significantly lower limiting potentials(-0.17,-0.18,-0.14,and-0.30 V,respectively).Excitingly,the limiting potential for CrMo and CrW combinations is 0 V,which are considered to be extremely suitable for the NRR process.The mechanism of"blocking and rebalance"is revealed by the exploration of charge transfer for phosphorus atoms in electron blocking areas.Moreover,the descriptorφis proposed with machine learning,which provides design strategies and accurate prediction for finding efficient DACs.This work not only offers promising catalysts TM_(A)TM_(B)@PC for NRR process but also provides design strategies by presenting the descriptorφ.展开更多
The failure phenomenon of thin-layered rock tunnels not only exhibits asymmetric spatial characteristics,but also significant time-dependent characteristics under high in-situ stress,which is attributed to the time-de...The failure phenomenon of thin-layered rock tunnels not only exhibits asymmetric spatial characteristics,but also significant time-dependent characteristics under high in-situ stress,which is attributed to the time-dependent fracture of thin-layered rocks.This paper conducted a series of true triaxial creep compression tests on typical thin-layered rock siliceous slate with acoustic emission technique to reveal its anisotropic time-dependent fracture characteristics.The anisotropic long-term strength,creep fracturing process,and fracture orientation characteristics of thin-layered rocks under different loading angles(b,u)and intermediate principal stress were summarized.A three-dimensional(3D)non-linear visco-plastic creep model for thin-layered rock was developed to simulate its anisotropic creep behavior.The time-dependent fracturing of rocks during true triaxial creep loading is reflected through the change of equivalent strain based on an improved Euler iteration method.By constructing the plastic potential function and overstress index related to loading angles and stress state,the anisotropic timedependent fracturing process and propagation of thin-layered rocks under different loading angles and intermediate principal stress are expounded.The model was validated experimentally to show it can reflect the long-term strength and creep deformation characteristics of thin-layered rocks under true triaxial compression.展开更多
Adynamic pitch strategy is usually adopted to improve the aerodynamic performance of the blade of awind turbine.The dynamic pitch motion will affect the linear vibration characteristics of the blade.However,these infl...Adynamic pitch strategy is usually adopted to improve the aerodynamic performance of the blade of awind turbine.The dynamic pitch motion will affect the linear vibration characteristics of the blade.However,these influences have not been studied in previous research.In this paper,the influences of the rigid pitch motion on the linear vibration characteristics of a wind turbine blade are studied.The blade is described as a rotating cantilever beam with an inherent coupled rigid-flexible vibration,where the rigid pitch motion introduces a parametrically excited vibration to the beam.Partial differential equations governing the nonlinear coupled pitch-bend vibration are proposed using the generalized Hamiltonian principle.Natural vibration characteristics of the inherent coupled rigid-flexible system are analyzed based on the combination of the assumed modes method and the multi-scales method.Effects of static pitch angle,rotating speed,and characteristics of harmonic pitch motion on flexible natural frequencies andmode shapes are discussed.It shows that the pitch amplitude has a dramatic influence on the natural frequencies of the blade,while the effects of pitch frequency and pith phase on natural frequencies are little.展开更多
Welding is commonly employed to connect large-scale components in practical engineering.Predicting the resulting deforma-tion and residual stresses during the welding process is typically essential.The thermal-elastic...Welding is commonly employed to connect large-scale components in practical engineering.Predicting the resulting deforma-tion and residual stresses during the welding process is typically essential.The thermal-elastic-plastic method simulates the welding process by examining heat distribution and elastic-plastic stresses.Despite its high computational accuracy,this method is often time-consuming,rendering it less suitable for large component welding predictions.In contrast,the inherent strain method skips the welding process and fo-cuses on the inherent strain in the weld and joint areas post-welding.This method is fast and convenient,particularly suitable for the analysis of large and complex structures.The results show that the error rate is 4.6%when using the inherent strain method to calculate the welding deformation of the test plate.In the calculation of welded parts,the error rate is 5%,which is within the tolerance of the actual engineering.In this paper,the simulation accuracy of the deformation results of the inherent strain method is validated by simulating fusion vacuum ves-sel mockup,aiming to reduce the cost of welding analysis by using this method and to provide reference for practical welding applications.展开更多
The uncertainty principle is a fundamental principle of quantum mechanics, but its exact mathematical expression cannot obtain correct results when used to solve theoretical problems such as the energy levels of hydro...The uncertainty principle is a fundamental principle of quantum mechanics, but its exact mathematical expression cannot obtain correct results when used to solve theoretical problems such as the energy levels of hydrogen atoms, one-dimensional deep potential wells, one-dimensional harmonic oscillators, and double-slit experiments. Even after approximate treatment, the results obtained are not completely consistent with those obtained by solving Schrödinger’s equation. This indicates that further research on the uncertainty principle is necessary. Therefore, using the de Broglie matter wave hypothesis, we quantize the action of an elementary particle in natural coordinates and obtain the quantization condition and a new deterministic relation. Using this quantization condition, we obtain the energy level formulas of an elementary particle in different conditions in a classical way that is completely consistent with the results obtained by solving Schrödinger’s equation. A new physical interpretation is given for the particle eigenfunction independence of probability for an elementary particle: an elementary particle is in a particle state at the space-time point where the action is quantized, and in a wave state in the rest of the space-time region. The space-time points of particle nature and the wave regions of particle motion constitute the continuous trajectory of particle motion. When an elementary particle is in a particle state, it is localized, whereas in the wave state region, it is nonlocalized.展开更多
This thesis takes the Skopostheorie as the guiding principle,analyzes and explains some important yet tend-to-be neglected standards,that is,the inherent characteristics unique to each product or service category.By m...This thesis takes the Skopostheorie as the guiding principle,analyzes and explains some important yet tend-to-be neglected standards,that is,the inherent characteristics unique to each product or service category.By means of analyzing cases,either successful or undesirable,it suggests the brand name translation had better imply their underlying features.Such principles may result in amazing translations.展开更多
文摘Clay deposits typically exhibit significant degrees of heterogeneity and anisotropy in their strength and stiffness properties.Such non-monotonic responses can significantly impact the stability analysis and design of overlying shallow foundations.In this study,the undrained bearing capacity of shallow foundations resting on inhomogeneous and anisotropic clay layers subjected to oblique-eccentric combined loading is investigated through a comprehensive series of finite element limit analysis(FELA)based on the well-established lower-bound theorem and second-order cone programming(SOCP).The heterogeneity of normally consolidated(NC)clays is simulated by adopting a well-known general model of undrained shear strength increasing linearly with depth.In contrast,for overconsolidated(OC)clays,the variation of undrained shear strength with depth is considered to follow a bilinear trend.Furthermore,the inherent anisotropy is accounted for by adopting different values of undrained shear strength along different directions within the soil medium,employing an iterative-based algorithm.The results of numerical simulations are utilized to investigate the influences of natural soil heterogeneity and inherent anisotropy on the ultimate bearing capacity,failure envelope,and failure mechanism of shallow foundations subjected to the various combinations of vertical-horizontal(V-H)and vertical-moment(V-M)loads.
基金Supported by the National Key Research and Development Program of China(2016YFB0301701)National Natural Science Foundation of China(21606258).
文摘With a growing population, an increasing number of petrochemical facilities are built with larger capacity and more complexity, which pose a great risk to assets, community and environment. The value of inherently safer design is recognized with time by all stakeholders, and an effective tool is needed to evaluate and compare inherent safety of alternative technologies. This study developed a safety index to evaluate existing technologies for their safety levels and guide inherently safer design. The Integrated Risk-based Safety Index(IRSI) was developed based on a comprehensive review of petrochemical processes, incident cases from Sinopec and US Chemical Safety Board, and existing safety index systems. The IRSI included all major hazards, including fire, explosion,toxic release, dust explosion, physical explosion, and runaway. Also, the integrated life cycle approach considered chemical hazards, equipment failure rates and safety measures in this risk-based index. Advanced modeling techniques, PHAST simulation and Neural Network, were used in the development of three novel sub-indices in the projects, fire, explosion and toxic release. The index system could be easily incorporated into a user friendly tool for the ease of application. A case study of hydrogen dioxide was conducted using the IRSI, which showed its capability for evaluating the safety level of process facilities.
基金Foundation of Tianjin Medical University(No.2006x9d2)the National Natural ScienceFoundation of Chinathe Major State Basic Research Development Program of China(No.20502008) for financialsupport
文摘A one-step procedure is developed to synthesize inherently chiral p-tert-butylcalix[4]azacrown 1 through etherification between p-tert-butylcalix[4]arene and compound 3, which can be amplifed to efficiently prepare more inherently cbiral calix[4]arenes in ABHH substitution pattern.
文摘Digraph-based causal models have been widely used to model the cause and effect behavior of process systems. Signed digraphs （SDG） capture the direction of the effect. It should be mentioned that there are loops in SDG generated from chemical process. From the point of the inherent operability, the worst unsafe factor is the SDG having positive loops that means any disturbance occurring within the loop will propagate through the nodes one by one and are amplified gradually, so the system may lose control, which may lead to an accident. So finding the positive loops in a SDG and treating these unsafe factors in a proper manner can improve the inherent safety of a chemical process. This article proposed a method that can detect the above-mentioned unsafe factors in the proc- ess conceptual design stage automatically through the analysis of the SDG generated from the chemical process. A case study is illustrated to show the working of the algorithm, and then a complicated case from industry is studied to depict the effectiveness of the proposed algorithm.
基金The authors gratefully acknowledge NSFC(grant nos.22222107,22171186)China Postdoctoral Science Foundation(2023M742365)+2 种基金Postdoctoral Fellowship Program of CPSF(GZC20231671)ShanghaiTech University start-up funding for financial support.Prof.Guangxin Liang was acknowledged for sharing the optical rotation polarimeter,and Mr.Huanchao Gu was acknowledged for the assistance with X-ray crystallographic analysissupport from Analytical Instrumentation Center(#SPST-AIC10112914),SPST,ShanghaiTech University.
文摘Dibenzo[b,fi[1,5]diazocines are a class of eight-membered heterocycles,which exhibit unique rigid saddle-shaped structure and possess inherent chirality.In this study,we report a convenient and straightforward method for the catalytic enantioselective synthesis of these unique chiral molecules through chiral phosphoric acid-catalyzed dimerization of 2-acylbenzoisocyanates.Notably,the addition of corresponding 2-acylaniline as the co-catalyst significantly improved the efficiency of these reactions,and a simple phase separation operation resulted in products with excellent enantiopurity.Experimental studies were performed to elucidate the mechanism behind these reactions,leading to the proposal of a plausible reaction mechanism based on the study findings.
文摘Erratum to Soil Ecol.Lett.Doi:10.1007/s42832-021-0089-z The original version of this article unfortunately contained a mistake.The Figure 7B legend for two of the found genera is missing.The online versin of the original article can be found at https://doi.org/10.1007/s42832-021-0089-z.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20625206 & 20372064)the National Basic Research Project (Grant Nos. 2007CB808000 & 2008CB617501), and the Chinese Academy of Sciences
文摘A series of novel N,O-type chiral ligands derived from enantiopure inherently chiral calix[4]arenes containing quinolin-2-yl-methanol moiety in the cone or partialcone conformation have been synthe-sized and characterized. Moreover,they have been applied to the catalytic asymmetric addition of diethylzinc to benzaldehyde,which represents the first example that the inherently chiral calixarene can be used as the chiral ligands for the catalytic asymmetric synthesis.
基金Natural Science Foundation of Shandong Province(ZR2020ME020)。
文摘Through a modified inherent strain model based on the minimum residual stress and deformation,three building schemes with different building postures and support structures were evaluated by finite element analysis.Results demonstrate that according to the principle of reducing the overall height of the building and reducing the support structure with a large tilt angle from the building direction,the residual stress and deformation can be effectively reduced by proper design of building posture and support before laser powder bed melting.Moreover,without the data of thermophysical property variation of Ti-6Al-4V artificial knee implants with temperature,predicting the residual stress and deformation with acceptable accuracy and reduced time cost can be achieved by the inherent strain model.
基金financially supported by the National Natural Science Foundation of China(No.22273079)。
文摘Sodium alginate(SA)is generally considered highly hydrophilic due to two hydroxyl groups and a carboxylate group on each pyranose ring.However,SA will form a gel after dissolving in water for a certain period.The two properties of SA,hydrophilicity and gelation,seem to be paradoxical.In this study,to explore the mechanism behind these paradoxical properties,the single-chain behaviors of SA in various liquid environments have been investigated by using single-molecule force spectroscopy(SMFS).In nonpolar solvents such as nonane,SA exhibits its single-chain inherent elasticity consistent with the theoretical elasticity derived from quantum mechanical(QM)calculations.Notably,the experimental curve of SA obtained in water shows a long plateau in the low force region.Further research reveals that this phenomenon is driven by the hydrophobic effect.Additionally,SA shows greater rigidity than its inherent elasticity in the middle and high force regions due to electrostatic repulsion between carboxylate groups on adjacent sugar rings.Comparative single-molecule studies suggest that SA exhibits considerable hydrophobicity,offering new insights into the gelation process in water.
基金supported by financial support from the National Natural Science Foundation of China(Grant Nos.52309122 and U2340229)the Innovation Team of Changjiang River Scientific Research Institute(Grant No.CKSF2024329/YT).
文摘Large-scale and heavily jointed rocks have inherent planes of anisotropy and secondary structural planes,such as dominant joint sets and random fractures,which result in significant differences in their failure mechanism and deformation behavior compared to other rock types.To address this issue,inherent anisotropic rocks with large-scale and dense joints are considered to be composed of the rock matrix,inherent planes of anisotropy,and secondary structural planes.Then a new implicit continuum model called LayerDFN is developed based on the crack tensor and damage tensor theories to characterize the mechanical properties of inherent anisotropic rocks.Furthermore,the LayerDFN model is implemented in the FLAC3D software,and a series of numerical results for typical example problems is compared with those obtained from the 3DEC,the analytical solutions,similar classical models,laboratory uniaxial compression tests,and field rigid bearing plate tests.The results demonstrate that the LayerDFN model can effectively capture the anisotropic mechanical properties of inherent anisotropic rocks,and can quantitatively characterize the damaging effect of the secondary structural planes.Overall,the numerical method based on the LayerDFN model provides a comprehensive and reliable approach for describing and analyzing the behavior of inherent anisotropic rocks,which will provide valuable insights for engineering design and decision-making processes.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52109143 and 12062026)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(China Institute of Water Resources and Hydropower Research)(Grant No.IWHRSKL-KF202305).
文摘The mechanical properties of stratified rocks are closely related not only to the stress state but also to the inherent structural anisotropy,which can be represented by the occurrence of bedding planes.This research aims to enhance the understanding of the anisotropic deformation and failure behaviors of stratified rocks by proposing a novel coupled elastoplastic-damage constitutive model.In this constitutive model,a scalar anisotropic parameter(stress-structure mixed invariant)based on the Pietruszczak–Mroz anisotropic theory is incorporated into a nonlinear yield surface,which accounts for the combined effects of the stress state and bedding structure on the anisotropic strength behaviors of stratified rocks.A damage-driven function governs the expansion and contraction of the anisotropic yield surface in the pre-peak strain hardening and post-peak strain-softening regions.The strength and deformation characteristics under multiaxial stress conditions are represented by incorporating the Lode's angle into the yield and plastic potential functions.Numerical simulations are conducted to facilitate a comparison with the conventional and true triaxial compression test data for several stratified rocks.The simulation results demonstrate good agreement with the test data,validating the effectiveness of the proposed constitutive model.This study provides theoretical and technical support for addressing engineering challenges involving stratified rocks.
基金supported by Research Deputy of Ferdowsi University of Mashhad.The provided grant(No.16759-03/12/89)
文摘In the present article, we study the effect of inherent anisotropy, i.e., initial bedding angle of particles and associated voids on macroscopic mechanical behavior of granular materials, by numerical simulation of several biaxial compression tests using the discrete element method （DEM）. Particle shape is considered to be irregular convex-polygonal. The effect of inherent anisotropy is investigated by following the evolution of mobilized shear strength and volume change during loading. As experimental tests have already shown, numerical simulations also indicate that initial anisotropic condition has a great influence on the strength and deformational behavior of granular assemblies. Comparison of simulations with tests using oval particles, shows that angularity influences both the mobilized shear strength and the volume change regime, which originates from the interlocking resistance between particles.
基金the National Natural Science Foundation of China(grant nos.21871268 and 22071250)the Natural Science Foundation of Guangdong Province of China(grant no.2020A1515011428)the“BAGUI Scholar”Program of Guangxi Province of China,and the SKLRD Project(grant no.SKLRD-Z-202014)for financial support.
文摘Inherently chiral 6,7-diphenyldibenzo[e,g][1,4]diazocine(DDD)has been synthesized enantioselectively for the first time via chiral phosphoric acid(CPA)-catalyzed cyclocondensation of readily available[1,1′-biphenyl]-2,2′-diamine(1a)and benzil(2a)in 82%yield,with 98%ee under mild reaction conditions.The strategy could also be applied to racemic biaryl diamines through kinetic resolution.The unexpectedly high interconversion energy barriers between the enantiomers(ΔG=39.5 kcal/mol)and the chemical stability rendered DDD an ideal platform for developing new chiral ligands and catalysts.Unique inherently chiralDDD-based phosphoramidites,phosphoric acid,mono-and diphosphine ligands were prepared from optically pure diphenol derivative DDDOL as a common precursor.Preliminary asymmetric reactions catalyzed by Pd or Rh in the presence of newly developed ligands exhibited comparable or even better enantioselectivities than the corresponding BINOLor SPINOL-derived ligands.Density functional theory calculation revealed the origin of the enantioselectivity during the process.
基金supported by the Natural Science Foundation of Fujian Province,China(No.2021J05266)the Talents Introduction Program of Xiamen University of Technology,China(No.YKJ19019R)+1 种基金the Young and Middle-aged Teachers Education Scientific Research Project of Fujian Province(No.JAT190657)supported under Australian Research Council/Discovery Early Career Researcher Award(DECRA)funding scheme(project No.DE230100180).
文摘Nowadays,the predominant source for approximately 90%of epoxy resin materials worldwide is the diglycidyl ether of bisphenol A(DGEBA).However,the increasing recognition of environmental concerns,such as global warming and the depletion of petroleum reserves,necessitates the exploration of alternative options,specifically bio-epoxy resin derived from sustainable resources.Nonetheless,the inadequate flame retardancy of bio-epoxy resin presents a notable drawback,limiting its applicability in high-risk environments.The objective of this review article is to provide a concise overview of the latest and upto-date advances in flame-retardant epoxy resins derived from sustainable sources.Firstly,the discussion encompasses inherently flame-retardant bio-based epoxy resins,considering both bio-based epoxy monomers and bio-based curing agents,focusing on their flame retardancy and mechanical properties.Furthermore,the utilization of phosphorus-containing and silicon-containing additives in bio-based epoxy is explored.Additionally,a comprehensive evaluation of partially bio-based intrinsically flame retardant epoxy resins is provided.Finally,this article offers an extensive survey of the current state-of-the-art in the field and presents future perspectives,serving as a valuable resource for researchers engaged in the study of flame-retardant epoxy resins derived from sustainable resources.
基金supports by the National Natural Science Foundation of China (NSFC,Grant No.52271113)the Natural Science Foundation of Shaanxi Province,China (2020JM-218)+1 种基金the Fundamental Research Funds for the Central Universities (CHD300102311405)HPC platform,Xi’an Jiaotong University。
文摘Compared to single atom catalysts(SACs),the introduction of dual atom catalysts(DACs)has a significantly positive effect on improving the efficiency in the electrocatalytic nitrogen reduction reaction(NRR)which provides an environmental alternative to the Haber-Bosch process.However,the research on the mechanism and strategy of designing bimetallic combinations for better performance is still in its early stages.Herein,based on"blocking and rebalance"mechanism,45 combinations of bimetallic pair dopedα-phosphorus carbide(TM_(A)TM_(B)@PC)are investigated as efficient NRR catalysts through density functional theory and machine learning method.After a multi-step screening,the combinations of TiV,TiFe,MnMo,and FeW exhibit highly efficient catalytic performance with significantly lower limiting potentials(-0.17,-0.18,-0.14,and-0.30 V,respectively).Excitingly,the limiting potential for CrMo and CrW combinations is 0 V,which are considered to be extremely suitable for the NRR process.The mechanism of"blocking and rebalance"is revealed by the exploration of charge transfer for phosphorus atoms in electron blocking areas.Moreover,the descriptorφis proposed with machine learning,which provides design strategies and accurate prediction for finding efficient DACs.This work not only offers promising catalysts TM_(A)TM_(B)@PC for NRR process but also provides design strategies by presenting the descriptorφ.
基金the financial support from the 111 Project(Grant No.B17009)the Liao Ning Revitalization Talents Program(Grant No.XLYCYSZX1902).
文摘The failure phenomenon of thin-layered rock tunnels not only exhibits asymmetric spatial characteristics,but also significant time-dependent characteristics under high in-situ stress,which is attributed to the time-dependent fracture of thin-layered rocks.This paper conducted a series of true triaxial creep compression tests on typical thin-layered rock siliceous slate with acoustic emission technique to reveal its anisotropic time-dependent fracture characteristics.The anisotropic long-term strength,creep fracturing process,and fracture orientation characteristics of thin-layered rocks under different loading angles(b,u)and intermediate principal stress were summarized.A three-dimensional(3D)non-linear visco-plastic creep model for thin-layered rock was developed to simulate its anisotropic creep behavior.The time-dependent fracturing of rocks during true triaxial creep loading is reflected through the change of equivalent strain based on an improved Euler iteration method.By constructing the plastic potential function and overstress index related to loading angles and stress state,the anisotropic timedependent fracturing process and propagation of thin-layered rocks under different loading angles and intermediate principal stress are expounded.The model was validated experimentally to show it can reflect the long-term strength and creep deformation characteristics of thin-layered rocks under true triaxial compression.
基金supported by the University Outstanding Youth Researcher Support Program of the Education Department of Anhui Province,the National Natural Science Foundation of China(Grant Nos.11902002 and 51705002)the Sichuan Provincial Natural Science Foundation(Grant No.2022NSFSC0275)+1 种基金the Science and Technology Research Project of Chongqing Municipal Education Commission(Grant No.KJQN201901146)the Special Key Project of Technological Innovation and Application Development in Chongqing(Grant No.cstc2020jscx-dxwtBX0048).
文摘Adynamic pitch strategy is usually adopted to improve the aerodynamic performance of the blade of awind turbine.The dynamic pitch motion will affect the linear vibration characteristics of the blade.However,these influences have not been studied in previous research.In this paper,the influences of the rigid pitch motion on the linear vibration characteristics of a wind turbine blade are studied.The blade is described as a rotating cantilever beam with an inherent coupled rigid-flexible vibration,where the rigid pitch motion introduces a parametrically excited vibration to the beam.Partial differential equations governing the nonlinear coupled pitch-bend vibration are proposed using the generalized Hamiltonian principle.Natural vibration characteristics of the inherent coupled rigid-flexible system are analyzed based on the combination of the assumed modes method and the multi-scales method.Effects of static pitch angle,rotating speed,and characteristics of harmonic pitch motion on flexible natural frequencies andmode shapes are discussed.It shows that the pitch amplitude has a dramatic influence on the natural frequencies of the blade,while the effects of pitch frequency and pith phase on natural frequencies are little.
基金supported by the National Key Scientific and Technological Infrastructure Construction Project(No.2018-000052-73-01-001228)National Natural Science Foundation of China Young Scientists Fund Project(12105185)Science Foundation of Institute of Plasma Physics,Chinese Academy of Sciences(No.DSJJ-2023-06).
文摘Welding is commonly employed to connect large-scale components in practical engineering.Predicting the resulting deforma-tion and residual stresses during the welding process is typically essential.The thermal-elastic-plastic method simulates the welding process by examining heat distribution and elastic-plastic stresses.Despite its high computational accuracy,this method is often time-consuming,rendering it less suitable for large component welding predictions.In contrast,the inherent strain method skips the welding process and fo-cuses on the inherent strain in the weld and joint areas post-welding.This method is fast and convenient,particularly suitable for the analysis of large and complex structures.The results show that the error rate is 4.6%when using the inherent strain method to calculate the welding deformation of the test plate.In the calculation of welded parts,the error rate is 5%,which is within the tolerance of the actual engineering.In this paper,the simulation accuracy of the deformation results of the inherent strain method is validated by simulating fusion vacuum ves-sel mockup,aiming to reduce the cost of welding analysis by using this method and to provide reference for practical welding applications.
文摘The uncertainty principle is a fundamental principle of quantum mechanics, but its exact mathematical expression cannot obtain correct results when used to solve theoretical problems such as the energy levels of hydrogen atoms, one-dimensional deep potential wells, one-dimensional harmonic oscillators, and double-slit experiments. Even after approximate treatment, the results obtained are not completely consistent with those obtained by solving Schrödinger’s equation. This indicates that further research on the uncertainty principle is necessary. Therefore, using the de Broglie matter wave hypothesis, we quantize the action of an elementary particle in natural coordinates and obtain the quantization condition and a new deterministic relation. Using this quantization condition, we obtain the energy level formulas of an elementary particle in different conditions in a classical way that is completely consistent with the results obtained by solving Schrödinger’s equation. A new physical interpretation is given for the particle eigenfunction independence of probability for an elementary particle: an elementary particle is in a particle state at the space-time point where the action is quantized, and in a wave state in the rest of the space-time region. The space-time points of particle nature and the wave regions of particle motion constitute the continuous trajectory of particle motion. When an elementary particle is in a particle state, it is localized, whereas in the wave state region, it is nonlocalized.
文摘This thesis takes the Skopostheorie as the guiding principle,analyzes and explains some important yet tend-to-be neglected standards,that is,the inherent characteristics unique to each product or service category.By means of analyzing cases,either successful or undesirable,it suggests the brand name translation had better imply their underlying features.Such principles may result in amazing translations.
