Nonlinear constitutive models of rock structural plane and their applications

Structural planes play an important role in controlling the stability of rock engineering,and the influence of structural planes should be considered in the design and construction process of rock engineering.In this paper,mechanical properties,constitutive theory,and numerical application of structural plane are studied by a combination method of laboratory tests,theoretical derivation,and program development.The test results reveal the change laws of various mechanical parameters under different roughness and normal stress.At the pre-peak stage,a non-stationary model of shear stiffness is established,and threedimensional empirical prediction models for initial shear stiffness and residual stage roughness are proposed.The nonlinear constitutive models are established based on elasto-plastic mechanics,and the algorithms of the models are developed based on the return mapping algorithm.According to a large number of statistical analysis results,empirical prediction models are proposed for model parameters expressed by structural plane characteristic parameters.Finally,the discrete element method(DEM)is chosen to embed the constitutive models for practical application.The running programs of the constitutive models have been compiled into the discrete element model library.The comparison results between the proposed model and the Mohr-Coulomb slip model show that the proposed model can better describe nonlinear changes at different stages,and the predicted shear strength,peak strain and shear stiffness are closer to the test results.The research results of the paper are conducive to the accurate evaluation of structural plane in rock engineering.

Electrocatalytic oxygen evolution activities of metal chalcogenides and phosphides:Fundamentals,origins,and future strategies

The development of inexpensive and efficient electrocatalysts is key to commercializing energy-related electrocatalytic techniques such as water electrolyzers and metal-air batteries.In particular,novel oxygen evolution reaction(OER)pre-catalysts,such as transition metal chalcogenides(TMCs)and phosphides(TMPs),have evolved in recent years from traditional stable OER electrocatalysts,which show superior OER electrocatalytic performance compared with transition metal oxides(TMOs)or(oxy)hydroxides(TMOHs).In this feature article,we summarize recent advances in the development of TMCand TMP-based OER electrocatalysts,as well as approaches to improve the OER performance in terms of morphology,structure,composition,surface engineering,lattice-strained and in-situ transformation in the electrolysis process.In particular,the electrochemical stability of TMCs and TMPs in alkaline electrolytes and the evolution of morphology,structure and composition under OER conditions are discussed.In the last section,we discuss the challenges that need to be addressed in this specific area of research and the implications for further research.

Discussion of the Relationship between Fairness and Efficiency——Based on Rawls'“A Theory of Justice”

Since China’s reform and opening up,from the Third Plenary Session of the 14th Central Committee of the Communist Party of China that put forward"efficiency first and fairness"to the 18th National Congress of the Communist Party of China,"first distribution and redistribution must deal with the relationship between fairness and efficiency,and redistribution pays more attention to fairness"Distribution policy,in 2021,the tenth meeting of the Central Finance and Economics Committee clearly stated that it is necessary to promote common prosperity in stages.The relationship between fairness and efficiency has always been the basic principle and standard for the country to formulate policies,and it is also the core issue discussed by scholars.Both utilitarianism and Rawls'two principles of justice provide us with different perspectives to explore the relationship between fairness and efficiency.This article focuses on Rawls's critique of utilitarianism and the specific content of the two justice principles,and makes a simple discussion on the relationship between fairness and efficiency and its enlightenment on the formulation of distribution policies in our country.

Fiber-optic dual Fabry-Pérot interferometric carbon monoxide sensor with polyaniline/Co3O4/graphene oxide sensing membrane

An optical fiber dual Fabry-Perot interferometric carbon monoxide gas sensor based on PANI/Co3 O4/GO(PCG)sensing membrane coated on the end face of the optical fiber is proposed and fabricated.One end face of photonic crystal fiber(PCF)without cut-off wavelength is fused with a single-mode fiber(SMF),and the other end face of the PCF is coated with PCG sensing membrane.The collapsed layer formed during the air hole fusion of PCF is used as the first reflector,the interface between PCF and sensing membrane is used as the second reflector,and the interface between the sensing membrane and the air is used as the third reflector,thus the dual Fabry-Pe rot structure sensor is formed.The results show that the sensor has excellent sensitivity and selectivity to carbon monoxide.With the increasing concentration of carbon monoxide gas in the range of 0-60 ppm,the intensity of interference spectrum decreases.The sensitivity of the sensor is 0.3473 dB m/ppm,and its linearity is good.The response time and recovery time are 68 s and 106 s,respectively.The sensor has the advantages of the compact size,low cost,high sensitivity,strong selectivity and simple structure.It is suitable for the sensing detection of low concentration carbon monoxide gas.

Development of BINOL-Si complexes with large stokes shifts and their application as chemodosimeters for nerve agent

Three fluorescent BINOL-Si complexes(FS1,FS2 and FS3)were rationally designed and synthesized to detect diethyl chlorophosphate(DCP),a mimic of lethal nerve agents.These three fluorescent probes showed green,yellow and orange fluorescence,respectively.Moreover,the series of fluorescent probes has the characteristics of fast response time(4 s),low detection limit(0.0097 mmol/L),high sensitivity and naked eye detection.More important,a fiber optic sensor capable of detecting DCP vapor in real time was also prepared for the first time,the lowest detection limits(down to 4.4 ppb)were all lower than that of the IDLH(immediately dangerous to life or health)concentration of Sarin(7.0 ppb).