Retinal ganglion cells are the bridging neurons between the eye and the central nervous system,transmitting visual signals to the brain.The injury and loss of retinal ganglion cells are the primary pathological change...Retinal ganglion cells are the bridging neurons between the eye and the central nervous system,transmitting visual signals to the brain.The injury and loss of retinal ganglion cells are the primary pathological changes in several retinal degenerative diseases,including glaucoma,ischemic optic neuropathy,diabetic neuropathy,and optic neuritis.In mammals,injured retinal ganglion cells lack regenerative capacity and undergo apoptotic cell death within a few days of injury.Additionally,these cells exhibit limited regenerative ability,ultimately contributing to vision impairment and potentially leading to blindness.Currently,the only effective clinical treatment for glaucoma is to prevent vision loss by lowering intraocular pressure through medications or surgery;however,this approach cannot halt the effect of retinal ganglion cell loss on visual function.This review comprehensively investigates the mechanisms underlying retinal ganglion cell degeneration in retinal degenerative diseases and further explores the current status and potential of cell replacement therapy for regenerating retinal ganglion cells.As our understanding of the complex processes involved in retinal ganglion cell degeneration deepens,we can explore new treatment strategies,such as cell transplantation,which may offer more effective ways to mitigate the effect of retinal degenerative diseases on vision.展开更多
Overview of the DNA damage response(DDR)in tumor cells.DDR is a highly coordinated signaling network that repairs DNA damage caused by intrinsic cellular processes and extrinsic insults,thereby preventing genome insta...Overview of the DNA damage response(DDR)in tumor cells.DDR is a highly coordinated signaling network that repairs DNA damage caused by intrinsic cellular processes and extrinsic insults,thereby preventing genome instability.Depending on the type of damage,distinct DNA damage repair and DNA damage tolerance(DDT)pathways are involved and coordinately regulated.展开更多
Coral reef limestone(CRL)constitutes a distinctive marine carbonate formation with complex mechanical properties.This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experime...Coral reef limestone(CRL)constitutes a distinctive marine carbonate formation with complex mechanical properties.This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experimental testing,digital core technology,and theoretical modelling.Two CRL types with contrasting mesostructures were characterized across three scales.Macroscopically,CRL-I and CRL-II exhibited mean compressive strengths of 8.46 and 5.17 MPa,respectively.Mesoscopically,CRL-I featured small-scale highly interconnected pores,whilst CRL-II developed larger stratified pores with diminished connectivity.Microscopically,both CRL matrices demonstrated remarkable similarity in mineral composition and mechanical properties.A novel voxel average-based digital core scaling methodology was developed to facilitate numerical simulation of cross-scale damage processes,revealing network-progressive failure in CRL-I versus directional-brittle failure in CRL-II.Furthermore,a damage statistical constitutive model based on digital core technology and mesoscopic homogenisation theory established quantitative relationships between microelement strength distribution and macroscopic mechanical behavior.These findings illuminate the fundamental mechanisms through which mesoscopic structure governs the macroscopic mechanical properties of CRL.展开更多
Investigating the combined effects of mining damage and creep damage on slope stability is crucial,as it can comprehensively reveal the non-linear deformation characteristics of rock under their joint influence.This s...Investigating the combined effects of mining damage and creep damage on slope stability is crucial,as it can comprehensively reveal the non-linear deformation characteristics of rock under their joint influence.This study develops a fractional-order nonlinear creep constitutive model that incorporates the double damage effect and implements a non-linear creep subroutine for soft rock using the threedimensional finite difference method on the FLAC3D platform.Comparative analysis of the theoretical,numerical,and experimental results reveals that the fractional-order constitutive model,which incorporates the double damage effect,accurately reflects the distinct deformation stages of green mudstone during creep failure and effectively captures the non-linear deformation in the accelerated creep phase.The numerical results show a fitting accuracy exceeding 97%with the creep test curves,significantly outperforming the 61%accuracy of traditional creep models.展开更多
Magnesium(Mg)alloys,known for their low density and high specific strength,are widely used in the lightweight design of engineering structures.However,their complex mechanical behaviors,particularly including the cycl...Magnesium(Mg)alloys,known for their low density and high specific strength,are widely used in the lightweight design of engineering structures.However,their complex mechanical behaviors,particularly including the cyclic plasticity,damage,and fatigue failure influenced by dislocation slipping,twinning,detwinning,and their interactions,present significant challenges in ensuring the safety and reliability of Mg alloy components.Addressing these challenges requires a comprehensive understanding of such behaviors and their underlying micro-mechanisms,and the development of reliable constitutive models,damage models,and fatigue life prediction methods.This review highlights recent advancements in these topics by elaborating particularly on the intricate connections between the macroscopic plastic deformation and microscopic mechanisms of Mg alloys,and the initiation and propagation of microcracks and microvoids observed through experimental studies and numerical simulations.We also discuss the progress in the theoretical models that predict the cyclic plasticity and/or fatigue life of Mg alloys.Finally,some topics for future research are suggested.展开更多
Static adsorption and dynamic damage experiments were carried out on typical 8#deep coal rock of the Carboniferous Benxi Formation in the Ordos Basin,NW China,to evaluate the adsorption capacity of hydroxypropyl guar ...Static adsorption and dynamic damage experiments were carried out on typical 8#deep coal rock of the Carboniferous Benxi Formation in the Ordos Basin,NW China,to evaluate the adsorption capacity of hydroxypropyl guar gum and polyacrylamide as fracturing fluid thickeners on deep coal rock surface and the permeability damage caused by adsorption.The adsorption morphology of the thickener was quantitatively characterized by atomic force microscopy,and the main controlling factors of the thickener adsorption were analyzed.Meanwhile,the adsorption mechanism of the thickener was revealed by Zeta potential,Fourier infrared spectroscopy and X-ray photoelectron spectroscopy.The results show that the adsorption capacity of hydroxypropyl guar gum on deep coal surface is 3.86 mg/g,and the permeability of coal rock after adsorption decreases by 35.24%–37.01%.The adsorption capacity of polyacrylamide is 3.29 mg/g,and the permeability of coal rock after adsorption decreases by 14.31%–21.93%.The thickness of the thickener adsorption layer is positively correlated with the mass fraction of thickener and negatively correlated with temperature,and a decrease in pH will reduce the thickness of the hydroxypropyl guar gum adsorption layer and make the distribution frequency of the thickness of polyacrylamide adsorption layer more concentrated.Functional group condensation and intermolecular force are chemical and physical forces for adsorbing fracturing fluid thickener in deep coal rock.Optimization of thickener mass fraction,chemical modification of thickener molecular,oxidative thermal degradation of polymer and addition of desorption agent can reduce the potential damages on micro-nano pores and cracks in coal rock.展开更多
This paper aims to experimentally and numerically probe fatigue behaviours and lifetimes of 3D4D(three-dimensional four-directional)braided composite I-beam under four-point flexure spectrum loading.New fatigue damage...This paper aims to experimentally and numerically probe fatigue behaviours and lifetimes of 3D4D(three-dimensional four-directional)braided composite I-beam under four-point flexure spectrum loading.New fatigue damage models of fibre yarn,matrix and fibre–matrix interface are proposed,and fatigue failure criteria and PFDA(Progressive Fatigue Damage Algorithm)are thus presented for meso-scale fatigue damage modelling of 3D4D braided composite I-beam.To validate the aforementioned model and algorithm,fatigue tests are conducted on the 3D4D braided composite I-beam under four-point flexure spectrum loading,and fatigue failure mechanisms are analyzed and discussed.Novel global–local FE(Finite Element)model based on the PFDA is generated for modelling progressive fatigue failure process and predicting fatigue life of 3D4D braided composite I-beam under four-point flexure spectrum loading.Good agreement has been achieved between experimental results and predictions,demonstrating the effective usage of new model.It is shown that matrix cracking and interfacial debonding initially initiates on top surface of top flange of I-beam,and then gradually propagates from the side surface of top flange to the intermediate web along the braiding angle,and considerable fiber breakage finally causes final fatigue failure of I-beam.展开更多
Localized rock failures,like cracks or shear bands,demand specific attention in modeling for solids and structures.This is due to the uncertainty of conventional continuum-based mechanical models when localized inelas...Localized rock failures,like cracks or shear bands,demand specific attention in modeling for solids and structures.This is due to the uncertainty of conventional continuum-based mechanical models when localized inelastic deformation has emerged.In such scenarios,as macroscopic inelastic reactions are primarily influenced by deformation and microstructural alterations within the localized area,internal variables that signify these microstructural changes should be established within this zone.Thus,localized deformation characteristics of rocks are studied here by the preset angle shear experiment.A method based on shear displacement and shear stress differences is proposed to identify the compaction,yielding,and residual points for enhancing the model's effectiveness and minimizing subjective influences.Next,a mechanical model for the localized shear band is depicted as an elasto-plastic model outlining the stress-displacement relation across both sides of the shear band.Incorporating damage theory and an elasto-plastic model,a proposed damage model is introduced to replicate shear stressdisplacement responses and localized damage evolution in intact rocks experiencing shear failure.Subsequently,a novel nonlinear mathematical model based on modified logistic growth theory is proposed for depicting the shear band's damage evolution pattern.Thereafter,an innovative damage model is proposed to effectively encompass diverse rock material behaviors,including elasticity,plasticity,and softening behaviors.Ultimately,the effects of the preset angles,temperature,normal stresses and the residual shear strength are carefully discussed.This discovery enhances rock research in the proposed damage model,particularly regarding shear failure mode.展开更多
Stress relaxation is a time-dependent phenomenon in rocks,characterized by a gradual decrease in stress magnitude while strain remains constant with time.This study introduces a novel experimental approach to investig...Stress relaxation is a time-dependent phenomenon in rocks,characterized by a gradual decrease in stress magnitude while strain remains constant with time.This study introduces a novel experimental approach to investigate deformation processes during the primary and secondary stages of stress relaxation and to differentiate the damage mechanisms occurring during relaxation from those under monotonic loading.To this end,the deformation behavior of prismatic-shaped homogeneous Stanstead granite(SG)rock specimens was monitored using two-dimensional digital image correlation(2D-DIC)in-sync with active ultrasonic sensing during stress relaxation and monotonic loading conditions.In particular,the SG specimens were allowed to undergo stress relaxation starting at a driving stress(σd)just above the crack damage(CD)threshold of the specimens,while their deformation characteristics were evaluated via 2D-DIC full-field strain maps and ultrasonic characteristics.The results indicate that the primary stage of relaxation is marked by accumulation of tensile damage at a decreasing rate,and the rate of damage accumulation reaches a steady state during the secondary stage of relaxation.Likewise,the ultrasonic amplitude reduced at a decreasing rate during the primary stage of relaxation and attained a constant rate of reduction during secondary relaxation.Additionally,a comparison of rock behavior during stress relaxation and monotonic loading conditions quantitatively demonstrated that SG dilates more during relaxation than under monotonic loading over a given range of damage values.This is interpreted to be associated with the fact that local extensional strains are diffuse under relaxation,in contrast with the more localized nature of damage under monotonic loading conditions.展开更多
Drive-by techniques for bridge health monitoring have drawn increasing attention from researchers and practitioners,in the attempt to make bridge condition-based monitoring more cost-efficient.In this work,the authors...Drive-by techniques for bridge health monitoring have drawn increasing attention from researchers and practitioners,in the attempt to make bridge condition-based monitoring more cost-efficient.In this work,the authors propose a drive-by approach that takes advantage from bogie vertical accelerations to assess bridge health status.To do so,continuous wavelet transform is combined with multiple sparse autoencoders that allow for damage detection and localization across bridge span.According to authors’best knowledge,this is the first case in which an unsupervised technique,which relies on the use of sparse autoencoders,is used to localize damages.The bridge considered in this work is a Warren steel truss bridge,whose finite element model is referred to an actual structure,belonging to the Italian railway line.To investigate damage detection and localization performances,different operational variables are accounted for:train weight,forward speed and track irregularity evolution in time.Two configurations for the virtual measuring channels were investigated:as a result,better performances were obtained by exploiting the vertical accelerations of both the bogies of the leading coach instead of using only one single acceleration signal.展开更多
The trade-off between mechanistic interpretability,operational convenience,and predictive accuracy is challenging for predicting the lifetime of lithium-ion batteries.To resolve this contradiction,we propose a damage ...The trade-off between mechanistic interpretability,operational convenience,and predictive accuracy is challenging for predicting the lifetime of lithium-ion batteries.To resolve this contradiction,we propose a damage model based on fatigue damage theory and electrochemical impedance spectroscopy.The causal relationship of“fatigue damage→resistance increase→capacity fading”is revealed to describe the underlying mechanism.Charge transfer resistance is chosen as the variable to ensure the convenience of data acquisition.To verify the accuracy of the model,the electrochemical impedance spectrum and capacity of a graphene-coated silicon electrode at two charging rates are collected and analyzed.50% and 75% of the measured data are utilized as inputs to compare the prediction capabilities of the proposed damage model and the existing empirical model.The particle filter algorithm is adopted to train the parameters of both models.The maximum prediction error of the damage model is less than 3%,showing better prediction accuracy and medium-term prediction stability than the empirical model.Our work demonstrates that the proposed damage model is an effective way to resolve contradictions in lifetime prediction.展开更多
Polymer gels are widely used in water control and enhanced oil recovery in oil fields.However,the damage mechanism of polymer gels to layers with remaining oil and not requiring plugging and corresponding protective m...Polymer gels are widely used in water control and enhanced oil recovery in oil fields.However,the damage mechanism of polymer gels to layers with remaining oil and not requiring plugging and corresponding protective measures are unclear.In this paper,we investigated polymer gels'damage and protection performance through static gel-breaking experiments and dynamic plugging and oil recovery evaluations on rock cores.Moreover,nuclear magnetic resonance(NMR)technology was combined to analyze the damage performance of polymer gels on cores from the pore scale.In addition,a protective technique based on gel breakers for layers with remaining oil and not requiring plugging was proposed.Results showed that when polymer gels were injected into heterogeneous cores,they plugged high-permeability layers while also penetrating low-permeability layers.When the damage to the low-permeability layers was not alleviated,the conformance and oil displacement efficiency were significantly reduced.When the concentration of ammonium persulfate was 2%–5%,the gel-breaking time was shortest and the residue was very minimal.Therefore,ammonium persulfate could be used as a gel breaker and reservoir protective material.Furthermore,after injecting ammonium persulfate into heterogeneous reservoir cores,the gel damage on the face of low-permeability layers was relieved.Consequently,the improvement in sweep efficiency was achieved,showing the re-activation of the remaining oil in medium-low permeability layers.Therefore,the low-permeability layer protection process and core experiment study based on gel-breaking agents proposed in this study were suggested to provide a new technique for the field application of conformance modification agents,aiming to achieve higher recovery degrees.展开更多
The damage distribution of the same type of aircraft in similar service environments should be similar. Based on this assumption, to perform the maintenance and repair of aircraft composite structures, the damage of c...The damage distribution of the same type of aircraft in similar service environments should be similar. Based on this assumption, to perform the maintenance and repair of aircraft composite structures, the damage of composite structures in a certain type of aircraft were investigated. The time-varying damage distribution model was established and verified based on the damage of a 16-aircraft fleet. The results show that the quantitative proportions of structural damage are 74% for skin delamination, 22% for stringer delamination and 3% for stringer-skin interface debonding. The amount of structural damages increases linearly with service time while the proportion of different damages does not change. As the service time increases, the geometric parameter distribution of damage for the same type of aircraft gradually converges, which can be approximated using the same function. There are certain differences in the proportion and geometric parameter distribution of damages among different components and locations, and the differences do not change over time.展开更多
Silicon carbide(SiC)ceramics are extensively utilized in aerospace,national defense,and petrochemical industries due to their superior physical and chemical properties.The processing of bulk SiC ceramics necessitates ...Silicon carbide(SiC)ceramics are extensively utilized in aerospace,national defense,and petrochemical industries due to their superior physical and chemical properties.The processing of bulk SiC ceramics necessitates precise and efficient grinding techniques to produce components with satisfactory functionality.However,the inherent high hardness and brittleness of SiC ceramics present significant challenges during grinding,leading to severe brittle fracture and tool wear that compromise both surface integrity and production efficiency.Although ductile-regime grinding of SiC ceramics can be achieved by enhancing machine tool accuracy and stiffness while optimizing wheel performance alongside appropriate selection of process parameters,a comprehensive summary of the mechanisms underlying damage evolution during grinding is lacking,and a mature grinding process for SiC ceramics has yet to be developed.To bridge this gap,the sintering technologies,mechanical properties,and microstructures of SiC ceramics were briefly covered.The grinding-induced damage mechanism and low-damage grinding technologies of SiC ceramics were summarized.The fundamental science underlying the ductile deformation and removal mechanisms of brittle solids was emphasized.Additionally,attention was directed towards the critical role of hybrid energy field grinding in minimizing brittle damages and promoting removal efficiency.This review not only elucidates the intrinsic interactions between the work material and abrasives,but also offers valuable insights for optimizing the grinding processes of brittle solids.展开更多
The deterioration of rock mass in the Three Gorges reservoir area results from the coupled damage effects of macro-micro cracks and dry-wet cycles,and the coupled damage progression can be characterized by energy rele...The deterioration of rock mass in the Three Gorges reservoir area results from the coupled damage effects of macro-micro cracks and dry-wet cycles,and the coupled damage progression can be characterized by energy release rate.In this study,a series of dry-wet cycle uniaxial compression tests was conducted on fractured sandstone,and a method was developed for calculating macro-micro damage(D_(R))and energy release rates(Y_(R))of fractured sandstone subjected to dry-wet cycles by considering energy release rate,dry-wet damage and macro-micro damage.Therewith,the damage mechanisms and complex microcrack propagation patterns of rocks were investigated.Research indicates that sandstone degradation after a limited cycle count primarily exhibits exsolution of internal fillers,progressing to grain skeleton alteration and erosion with increased cycles.Compared with conventional methods,the D_(R) and Y_(R) methodologies exhibit heightened sensitivity to microcrack closure during compaction and abrupt energy release at the point of failure.Based on D_(R) and Y_(R),the failure process of fractured sandstone can be classified into six stages:stress adjustment(I),microcracks equal closure(II),nonlinear slow closure(III),low-speed extension(IV),rapid extension(V),and macroscopic main fracture emergence(VI).The abrupt change in damage energy release rate during stage V may serve as a reliable precursor for inducing failure.The stage-based classification may enhance traditional methods by tracking damage progression and accurately identifying rock failure precursors.The findings are expected to provide a scientific basis for understanding damage mechanisms and enabling early warning of reservoir-bank slope failure.展开更多
The emergence of laser technology has led to the gradual integration of laser weapon system(LaWS)into military scene,particularly in the field of anti-unmanned aerial vehicle(UAV),showcasing significant potential.Howe...The emergence of laser technology has led to the gradual integration of laser weapon system(LaWS)into military scene,particularly in the field of anti-unmanned aerial vehicle(UAV),showcasing significant potential.However,A current limitation lies in the absence of a comprehensive quantitative approach to assess the capabilities of LaWS.To address this issue,a damage effectiveness characterization model for LaWS is established,taking into account the properties of laser transmission through the atmosphere and the thermal damage effects.By employing this model,key parameters pertaining to the effectiveness of laser damage are determined.The impact of various spatial positions and atmospheric conditions on the damage effectiveness of LaWS have been examined,employing simulation experiments with diverse parameters.The conclusions indicate that the damage effectiveness of LaWS is contingent upon the spatial position of the target,resulting in a diminished effectiveness to damage on distant,low-altitude targets.Additionally,the damage effectiveness of LaWS is heavily reliant on the atmospheric condition,particularly in complex settings such as midday and low visibility conditions,where the damage effectiveness is substantially reduced.This paper provides an accurate and effective calculation method for the rapid decisionmaking of the operators.展开更多
A Combined Cycle Fatigue(CCF)life prediction model considering the effect of load sequence was proposed.To account for the interaction of high and low cycle fatigue,the CCF load was divided into two different loading ...A Combined Cycle Fatigue(CCF)life prediction model considering the effect of load sequence was proposed.To account for the interaction of high and low cycle fatigue,the CCF load was divided into two different loading paths of variable stress amplitude and stress ratio.Based on the iso-damage curves,a CCF life prediction model independent of fitting parameters was proposed,agreeing well with the experimental results.Finally,the effect of load sequence on CCF was discussed according to the fracture morphology of designed blade-like specimen.The results showed that the predicted CCF life was almost located in three-fold dispersion band for the LCF-HCF(LH)and HCF-LCF(HL)loading paths,especially for the average results of both.Compared with other models,the proposed model had better predictive and generalization abilities for multiple materials and variable experimental conditions.展开更多
Aiming at challenges posed by rock freezethaw(FT)in cold regions rock mass engineering,it is of great significance to analyze its macro-and micromechanical properties and damage laws for the smooth progress of constru...Aiming at challenges posed by rock freezethaw(FT)in cold regions rock mass engineering,it is of great significance to analyze its macro-and micromechanical properties and damage laws for the smooth progress of construction.In this study,indoor freezethaw cycle(FTC)tests on sandstone were conducted to analyze the mass change rate,density change rate,longitudinal wave velocity change rate,microstructure change and mechanical properties of sandstone after FTC.A microscopic FT damage variable reflecting the FT damage was defined based on the changes of rock porosity before and after the FTC,enabling the derivation of the total damage variable under the coupled action of FTC and mechanical loading.A damage evolution equation and a microscopic damage constitutive model for rock under coupled FTC and confining pressure were established by using Lemaitre’s strain equivalence principle,the theory of continuous damage mechanics,and the assumption that the failure of rock micro-units follows the SMP criterion.The rationality and accuracy of the model were verified using triaxial compression test data for FT-damaged rock.The results show that both macroand micro-mechanical properties of sandstone are degraded under the action of FTC,resulting in significant damage.The developed microscopic damage constitutive model can reflect the stress-strain characteristics of the whole process of FT rock triaxial compression,with excellent agreement observed between experimental and theoretical curves.This validates the reliability of the model and the methodology for determining its parameters.Additionally,defining the microscopic FT damage variable based on rock porosity changes is demonstrated to be a feasible and highly accurate approach to reflect rock FT damage degree.This model expands the damage model for rock under the coupling effect of FTC and confining pressure,further illuminating the damage mechanism and failure law in such environments.The findings provide references for the construction of rock mass engineering in cold regions.展开更多
Compared with blast mining only,blast mining after on-site hydraulic fracturing can make the mining easier and obtain better mining outcomes.To explore the effects of hydraulic fracturing on the blasting damages in co...Compared with blast mining only,blast mining after on-site hydraulic fracturing can make the mining easier and obtain better mining outcomes.To explore the effects of hydraulic fracturing on the blasting damages in coal seam,blasting experiments were carried out under biaxial confining pressure using the synthetic coal briquettes.The coal briquettes with the same mechanical properties as coal seam were prepared and the mica sheets with different radi and thicknesses were added to simulate the internal hydraulic fractures of different radi and openings.The internal damage distributions and stress attenuations of the coal briquette specimens with different hydraulic fracture radi and openings after the blasting were then measured using a rock ultrasonic tester and a static-dynamic strainmeter.Based on the rock blasting theory,the effects of hydraulic fractures with different radi and openings on the blast fracture propagation and coal seam damage were analyzed.The following conclusions are drawn:(1)The increases in hydraulic fracture radius mainly enhance the damages in the vertical direction to the hydraulic fracture,and can increase the vertical range of the severely damaged area by 20-25 cm.The increases in the hydraulic fracture opening mainly cause more severe damages along the direction of the hydraulic fracture and increase the horizontal range of the severely damaged area by 30 cm.(2)The area of the severely damaged area caused by blasting increases by 550 cm?as the hydraulic fracture radius increased from 5 to 15 cm.As the hydraulic fracture opening increased from 2 to 10 mm,and the area of the severely damaged area caused by blasting increases by 650 cm?.Therefore,the hydraulic fracture opening has greater impacts on the severely damaged area.(3)The increase in the hydraulic fracture length reduces the compression phase attenuation of the blast stress in the radial direction.Both the increases of the hydraulic fracture length and opening increase the absolute value of the tensile phase in the radial direction.(4)Increasing the hydraulic fracture radius and opening can greatly promote the development of blast fractures and enhance the damages to coal seam.Therefore,the coal seam mining effect can be improved by increasing the radi or openings of hydraulic fractures to adjust the main action direction of blast fracture.展开更多
Small nucleolar RNAs(snoRNAs)were previously regarded as a class of functionally conserved housekeeping genes,primarily involved in the regulation of ribosome biogenesis by ribosomal RNA(rRNA)modification.However,some...Small nucleolar RNAs(snoRNAs)were previously regarded as a class of functionally conserved housekeeping genes,primarily involved in the regulation of ribosome biogenesis by ribosomal RNA(rRNA)modification.However,some of them are involved in several biological processes via complex molecular mechanisms.DNA damage response(DDR)is a conserved mechanism for maintaining genomic stability to prevent the occurrence of various human diseases.It has recently been revealed that snoRNAs are involved in DDR at multiple levels,indicating their relevant theoretical and clinical significance in this field.The present review systematically addresses four main points,including the biosynthesis and classification of snoRNAs,the mechanisms through which snoRNAs regulate target molecules,snoRNAs in the process of DDR,and the significance of snoRNA in disease diagnosis and treatment.It focuses on the potential functions of snoRNAs in DDR to help in the discovery of the roles of snoRNAs in maintaining genome stability and pathological processes.展开更多
基金supported by the National Key Research and Development Program of China,No.2019YFA0111200the National Natural Science Foundation of China,Nos.U23A20436,82371047+3 种基金Key Research Project in Shanxi Province,No.202302130501008Shanxi Provincial Science Fund for Distinguished Young Scholars,No.202103021221008Key Research and Development Program in Shanxi Province,No.202204051001023Shanxi Medical University Doctor’s Startup Fund Project,No.SD22028(all to YG)。
文摘Retinal ganglion cells are the bridging neurons between the eye and the central nervous system,transmitting visual signals to the brain.The injury and loss of retinal ganglion cells are the primary pathological changes in several retinal degenerative diseases,including glaucoma,ischemic optic neuropathy,diabetic neuropathy,and optic neuritis.In mammals,injured retinal ganglion cells lack regenerative capacity and undergo apoptotic cell death within a few days of injury.Additionally,these cells exhibit limited regenerative ability,ultimately contributing to vision impairment and potentially leading to blindness.Currently,the only effective clinical treatment for glaucoma is to prevent vision loss by lowering intraocular pressure through medications or surgery;however,this approach cannot halt the effect of retinal ganglion cell loss on visual function.This review comprehensively investigates the mechanisms underlying retinal ganglion cell degeneration in retinal degenerative diseases and further explores the current status and potential of cell replacement therapy for regenerating retinal ganglion cells.As our understanding of the complex processes involved in retinal ganglion cell degeneration deepens,we can explore new treatment strategies,such as cell transplantation,which may offer more effective ways to mitigate the effect of retinal degenerative diseases on vision.
基金the National Natural Science Foundation of China(Grant No.82330090 and Grant No.82341006 to C.G.)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA0460403 to C.G.)the Natural Science Foundation of Shanxi Province(Grant No.202203021211155 to X.M.).
文摘Overview of the DNA damage response(DDR)in tumor cells.DDR is a highly coordinated signaling network that repairs DNA damage caused by intrinsic cellular processes and extrinsic insults,thereby preventing genome instability.Depending on the type of damage,distinct DNA damage repair and DNA damage tolerance(DDT)pathways are involved and coordinately regulated.
基金National Key Research and Development Program of China (No.2021YFC3100800)the National Natural Science Foundation of China (Nos.42407235 and 42271026)+1 种基金the Project of Sanya Yazhou Bay Science and Technology City (No.SCKJ-JYRC-2023-54)supported by the Hefei advanced computing center
文摘Coral reef limestone(CRL)constitutes a distinctive marine carbonate formation with complex mechanical properties.This study investigates the multiscale damage and fracture mechanisms of CRL through integrated experimental testing,digital core technology,and theoretical modelling.Two CRL types with contrasting mesostructures were characterized across three scales.Macroscopically,CRL-I and CRL-II exhibited mean compressive strengths of 8.46 and 5.17 MPa,respectively.Mesoscopically,CRL-I featured small-scale highly interconnected pores,whilst CRL-II developed larger stratified pores with diminished connectivity.Microscopically,both CRL matrices demonstrated remarkable similarity in mineral composition and mechanical properties.A novel voxel average-based digital core scaling methodology was developed to facilitate numerical simulation of cross-scale damage processes,revealing network-progressive failure in CRL-I versus directional-brittle failure in CRL-II.Furthermore,a damage statistical constitutive model based on digital core technology and mesoscopic homogenisation theory established quantitative relationships between microelement strength distribution and macroscopic mechanical behavior.These findings illuminate the fundamental mechanisms through which mesoscopic structure governs the macroscopic mechanical properties of CRL.
基金support from the National Natural Science Foundation of China(No.52308316)the Scientific Research Foundation of Weifang University(Grant No.2024BS42)+2 种基金China Postdoctoral Science Foundation(No.2022M721885)the Key Laboratory of Rock Mechanics and Geohazards of Zhejiang Province(No.ZJRMG-2022-01)supported by Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences(NO.SKLGME023017).
文摘Investigating the combined effects of mining damage and creep damage on slope stability is crucial,as it can comprehensively reveal the non-linear deformation characteristics of rock under their joint influence.This study develops a fractional-order nonlinear creep constitutive model that incorporates the double damage effect and implements a non-linear creep subroutine for soft rock using the threedimensional finite difference method on the FLAC3D platform.Comparative analysis of the theoretical,numerical,and experimental results reveals that the fractional-order constitutive model,which incorporates the double damage effect,accurately reflects the distinct deformation stages of green mudstone during creep failure and effectively captures the non-linear deformation in the accelerated creep phase.The numerical results show a fitting accuracy exceeding 97%with the creep test curves,significantly outperforming the 61%accuracy of traditional creep models.
基金supported by the National Natural Science Foundation of China(Nos.12192210,12192214,11921002,and 12302076)China Postdoctoral Science Foundation(No.2024M761630).
文摘Magnesium(Mg)alloys,known for their low density and high specific strength,are widely used in the lightweight design of engineering structures.However,their complex mechanical behaviors,particularly including the cyclic plasticity,damage,and fatigue failure influenced by dislocation slipping,twinning,detwinning,and their interactions,present significant challenges in ensuring the safety and reliability of Mg alloy components.Addressing these challenges requires a comprehensive understanding of such behaviors and their underlying micro-mechanisms,and the development of reliable constitutive models,damage models,and fatigue life prediction methods.This review highlights recent advancements in these topics by elaborating particularly on the intricate connections between the macroscopic plastic deformation and microscopic mechanisms of Mg alloys,and the initiation and propagation of microcracks and microvoids observed through experimental studies and numerical simulations.We also discuss the progress in the theoretical models that predict the cyclic plasticity and/or fatigue life of Mg alloys.Finally,some topics for future research are suggested.
基金Supported by National Natural Science Foundation of China(51674209)Sichuan Province Youth Science and Technology Innovation Team(2021JDTD0017).
文摘Static adsorption and dynamic damage experiments were carried out on typical 8#deep coal rock of the Carboniferous Benxi Formation in the Ordos Basin,NW China,to evaluate the adsorption capacity of hydroxypropyl guar gum and polyacrylamide as fracturing fluid thickeners on deep coal rock surface and the permeability damage caused by adsorption.The adsorption morphology of the thickener was quantitatively characterized by atomic force microscopy,and the main controlling factors of the thickener adsorption were analyzed.Meanwhile,the adsorption mechanism of the thickener was revealed by Zeta potential,Fourier infrared spectroscopy and X-ray photoelectron spectroscopy.The results show that the adsorption capacity of hydroxypropyl guar gum on deep coal surface is 3.86 mg/g,and the permeability of coal rock after adsorption decreases by 35.24%–37.01%.The adsorption capacity of polyacrylamide is 3.29 mg/g,and the permeability of coal rock after adsorption decreases by 14.31%–21.93%.The thickness of the thickener adsorption layer is positively correlated with the mass fraction of thickener and negatively correlated with temperature,and a decrease in pH will reduce the thickness of the hydroxypropyl guar gum adsorption layer and make the distribution frequency of the thickness of polyacrylamide adsorption layer more concentrated.Functional group condensation and intermolecular force are chemical and physical forces for adsorbing fracturing fluid thickener in deep coal rock.Optimization of thickener mass fraction,chemical modification of thickener molecular,oxidative thermal degradation of polymer and addition of desorption agent can reduce the potential damages on micro-nano pores and cracks in coal rock.
基金supported by the National Natural Science Foundation of China(No.12472340).
文摘This paper aims to experimentally and numerically probe fatigue behaviours and lifetimes of 3D4D(three-dimensional four-directional)braided composite I-beam under four-point flexure spectrum loading.New fatigue damage models of fibre yarn,matrix and fibre–matrix interface are proposed,and fatigue failure criteria and PFDA(Progressive Fatigue Damage Algorithm)are thus presented for meso-scale fatigue damage modelling of 3D4D braided composite I-beam.To validate the aforementioned model and algorithm,fatigue tests are conducted on the 3D4D braided composite I-beam under four-point flexure spectrum loading,and fatigue failure mechanisms are analyzed and discussed.Novel global–local FE(Finite Element)model based on the PFDA is generated for modelling progressive fatigue failure process and predicting fatigue life of 3D4D braided composite I-beam under four-point flexure spectrum loading.Good agreement has been achieved between experimental results and predictions,demonstrating the effective usage of new model.It is shown that matrix cracking and interfacial debonding initially initiates on top surface of top flange of I-beam,and then gradually propagates from the side surface of top flange to the intermediate web along the braiding angle,and considerable fiber breakage finally causes final fatigue failure of I-beam.
基金supported by the China Scholarship Council Program(Grant No.202008320274)it is also supported by Technical University of Munich.
文摘Localized rock failures,like cracks or shear bands,demand specific attention in modeling for solids and structures.This is due to the uncertainty of conventional continuum-based mechanical models when localized inelastic deformation has emerged.In such scenarios,as macroscopic inelastic reactions are primarily influenced by deformation and microstructural alterations within the localized area,internal variables that signify these microstructural changes should be established within this zone.Thus,localized deformation characteristics of rocks are studied here by the preset angle shear experiment.A method based on shear displacement and shear stress differences is proposed to identify the compaction,yielding,and residual points for enhancing the model's effectiveness and minimizing subjective influences.Next,a mechanical model for the localized shear band is depicted as an elasto-plastic model outlining the stress-displacement relation across both sides of the shear band.Incorporating damage theory and an elasto-plastic model,a proposed damage model is introduced to replicate shear stressdisplacement responses and localized damage evolution in intact rocks experiencing shear failure.Subsequently,a novel nonlinear mathematical model based on modified logistic growth theory is proposed for depicting the shear band's damage evolution pattern.Thereafter,an innovative damage model is proposed to effectively encompass diverse rock material behaviors,including elasticity,plasticity,and softening behaviors.Ultimately,the effects of the preset angles,temperature,normal stresses and the residual shear strength are carefully discussed.This discovery enhances rock research in the proposed damage model,particularly regarding shear failure mode.
基金support provided by the Indian Institute of Technology Delhi,India,and Colorado School of Mines,USA,for performing the work related to this research article is greatly appreciatedsupported by the IIT Delhi MFIRP Grant No.MI022762G+1 种基金partially by the U.S.Department of Energy,Office of Basic Energy Sciences,under Award Number DE-SC0019117support is gratefully acknowledged。
文摘Stress relaxation is a time-dependent phenomenon in rocks,characterized by a gradual decrease in stress magnitude while strain remains constant with time.This study introduces a novel experimental approach to investigate deformation processes during the primary and secondary stages of stress relaxation and to differentiate the damage mechanisms occurring during relaxation from those under monotonic loading.To this end,the deformation behavior of prismatic-shaped homogeneous Stanstead granite(SG)rock specimens was monitored using two-dimensional digital image correlation(2D-DIC)in-sync with active ultrasonic sensing during stress relaxation and monotonic loading conditions.In particular,the SG specimens were allowed to undergo stress relaxation starting at a driving stress(σd)just above the crack damage(CD)threshold of the specimens,while their deformation characteristics were evaluated via 2D-DIC full-field strain maps and ultrasonic characteristics.The results indicate that the primary stage of relaxation is marked by accumulation of tensile damage at a decreasing rate,and the rate of damage accumulation reaches a steady state during the secondary stage of relaxation.Likewise,the ultrasonic amplitude reduced at a decreasing rate during the primary stage of relaxation and attained a constant rate of reduction during secondary relaxation.Additionally,a comparison of rock behavior during stress relaxation and monotonic loading conditions quantitatively demonstrated that SG dilates more during relaxation than under monotonic loading over a given range of damage values.This is interpreted to be associated with the fact that local extensional strains are diffuse under relaxation,in contrast with the more localized nature of damage under monotonic loading conditions.
文摘Drive-by techniques for bridge health monitoring have drawn increasing attention from researchers and practitioners,in the attempt to make bridge condition-based monitoring more cost-efficient.In this work,the authors propose a drive-by approach that takes advantage from bogie vertical accelerations to assess bridge health status.To do so,continuous wavelet transform is combined with multiple sparse autoencoders that allow for damage detection and localization across bridge span.According to authors’best knowledge,this is the first case in which an unsupervised technique,which relies on the use of sparse autoencoders,is used to localize damages.The bridge considered in this work is a Warren steel truss bridge,whose finite element model is referred to an actual structure,belonging to the Italian railway line.To investigate damage detection and localization performances,different operational variables are accounted for:train weight,forward speed and track irregularity evolution in time.Two configurations for the virtual measuring channels were investigated:as a result,better performances were obtained by exploiting the vertical accelerations of both the bogies of the leading coach instead of using only one single acceleration signal.
基金supported by the National Natural Science Foundation of China(12021002,12472183,and 12041201).
文摘The trade-off between mechanistic interpretability,operational convenience,and predictive accuracy is challenging for predicting the lifetime of lithium-ion batteries.To resolve this contradiction,we propose a damage model based on fatigue damage theory and electrochemical impedance spectroscopy.The causal relationship of“fatigue damage→resistance increase→capacity fading”is revealed to describe the underlying mechanism.Charge transfer resistance is chosen as the variable to ensure the convenience of data acquisition.To verify the accuracy of the model,the electrochemical impedance spectrum and capacity of a graphene-coated silicon electrode at two charging rates are collected and analyzed.50% and 75% of the measured data are utilized as inputs to compare the prediction capabilities of the proposed damage model and the existing empirical model.The particle filter algorithm is adopted to train the parameters of both models.The maximum prediction error of the damage model is less than 3%,showing better prediction accuracy and medium-term prediction stability than the empirical model.Our work demonstrates that the proposed damage model is an effective way to resolve contradictions in lifetime prediction.
基金supported by the Natural Science Foundation of Xinjiang Uygur Autonomous Region(No.2022D01A250)the Karamay Innovative Environment Construction Plan(Innovative Talents)project(No.20212022hjcxrc0015).
文摘Polymer gels are widely used in water control and enhanced oil recovery in oil fields.However,the damage mechanism of polymer gels to layers with remaining oil and not requiring plugging and corresponding protective measures are unclear.In this paper,we investigated polymer gels'damage and protection performance through static gel-breaking experiments and dynamic plugging and oil recovery evaluations on rock cores.Moreover,nuclear magnetic resonance(NMR)technology was combined to analyze the damage performance of polymer gels on cores from the pore scale.In addition,a protective technique based on gel breakers for layers with remaining oil and not requiring plugging was proposed.Results showed that when polymer gels were injected into heterogeneous cores,they plugged high-permeability layers while also penetrating low-permeability layers.When the damage to the low-permeability layers was not alleviated,the conformance and oil displacement efficiency were significantly reduced.When the concentration of ammonium persulfate was 2%–5%,the gel-breaking time was shortest and the residue was very minimal.Therefore,ammonium persulfate could be used as a gel breaker and reservoir protective material.Furthermore,after injecting ammonium persulfate into heterogeneous reservoir cores,the gel damage on the face of low-permeability layers was relieved.Consequently,the improvement in sweep efficiency was achieved,showing the re-activation of the remaining oil in medium-low permeability layers.Therefore,the low-permeability layer protection process and core experiment study based on gel-breaking agents proposed in this study were suggested to provide a new technique for the field application of conformance modification agents,aiming to achieve higher recovery degrees.
文摘The damage distribution of the same type of aircraft in similar service environments should be similar. Based on this assumption, to perform the maintenance and repair of aircraft composite structures, the damage of composite structures in a certain type of aircraft were investigated. The time-varying damage distribution model was established and verified based on the damage of a 16-aircraft fleet. The results show that the quantitative proportions of structural damage are 74% for skin delamination, 22% for stringer delamination and 3% for stringer-skin interface debonding. The amount of structural damages increases linearly with service time while the proportion of different damages does not change. As the service time increases, the geometric parameter distribution of damage for the same type of aircraft gradually converges, which can be approximated using the same function. There are certain differences in the proportion and geometric parameter distribution of damages among different components and locations, and the differences do not change over time.
基金supported by the National Natural Science Foundation of China(Grant Nos.52375420,52322510)Natural Science Foundation of Heilongjiang Province of China(Grant No.YQ2023E014)+6 种基金National Key Research and Development Program of China(Grant No.2021YFB3400403)Shenzhen Science and Technology Program(Grant No.GNCWSSJH20240032)Self-Planned Task(Grant No.SKLRS202214B)of State Key Laboratory of Robotics and System(HIT),China Postdoctoral Science Foundation(Grant No.2022T150163)Young Elite Scientists Sponsorship Program by CAST(Grant No.YESS20220463)Open Fund of Key Laboratory of Microsystems and Microstructures Manufacturing(HIT)(Grant No.2022KM004)Open Foundation of Hunan Provincial Key Laboratory of High Efficiency and Precision Machining of Difficult-to-Cut Material(Grant No.E22445)Fundamental Research Funds for the Central Universities(Grant Nos.HIT.OCEF.2022024,FRFCU5710051122)。
文摘Silicon carbide(SiC)ceramics are extensively utilized in aerospace,national defense,and petrochemical industries due to their superior physical and chemical properties.The processing of bulk SiC ceramics necessitates precise and efficient grinding techniques to produce components with satisfactory functionality.However,the inherent high hardness and brittleness of SiC ceramics present significant challenges during grinding,leading to severe brittle fracture and tool wear that compromise both surface integrity and production efficiency.Although ductile-regime grinding of SiC ceramics can be achieved by enhancing machine tool accuracy and stiffness while optimizing wheel performance alongside appropriate selection of process parameters,a comprehensive summary of the mechanisms underlying damage evolution during grinding is lacking,and a mature grinding process for SiC ceramics has yet to be developed.To bridge this gap,the sintering technologies,mechanical properties,and microstructures of SiC ceramics were briefly covered.The grinding-induced damage mechanism and low-damage grinding technologies of SiC ceramics were summarized.The fundamental science underlying the ductile deformation and removal mechanisms of brittle solids was emphasized.Additionally,attention was directed towards the critical role of hybrid energy field grinding in minimizing brittle damages and promoting removal efficiency.This review not only elucidates the intrinsic interactions between the work material and abrasives,but also offers valuable insights for optimizing the grinding processes of brittle solids.
基金supported by the National Natural Science Foundation of China(Grant No.51978106)China Postdoctoral Science Foundation(Grant No.2022MD723831)Graduate Research and Innovation Foundation of Chongqing(Grant No.CYB240039).
文摘The deterioration of rock mass in the Three Gorges reservoir area results from the coupled damage effects of macro-micro cracks and dry-wet cycles,and the coupled damage progression can be characterized by energy release rate.In this study,a series of dry-wet cycle uniaxial compression tests was conducted on fractured sandstone,and a method was developed for calculating macro-micro damage(D_(R))and energy release rates(Y_(R))of fractured sandstone subjected to dry-wet cycles by considering energy release rate,dry-wet damage and macro-micro damage.Therewith,the damage mechanisms and complex microcrack propagation patterns of rocks were investigated.Research indicates that sandstone degradation after a limited cycle count primarily exhibits exsolution of internal fillers,progressing to grain skeleton alteration and erosion with increased cycles.Compared with conventional methods,the D_(R) and Y_(R) methodologies exhibit heightened sensitivity to microcrack closure during compaction and abrupt energy release at the point of failure.Based on D_(R) and Y_(R),the failure process of fractured sandstone can be classified into six stages:stress adjustment(I),microcracks equal closure(II),nonlinear slow closure(III),low-speed extension(IV),rapid extension(V),and macroscopic main fracture emergence(VI).The abrupt change in damage energy release rate during stage V may serve as a reliable precursor for inducing failure.The stage-based classification may enhance traditional methods by tracking damage progression and accurately identifying rock failure precursors.The findings are expected to provide a scientific basis for understanding damage mechanisms and enabling early warning of reservoir-bank slope failure.
基金supported by the National Social Science Foundation of China(2022-SKJJ-C-037)the National Natural Science Foundation of China General Program(72071209).
文摘The emergence of laser technology has led to the gradual integration of laser weapon system(LaWS)into military scene,particularly in the field of anti-unmanned aerial vehicle(UAV),showcasing significant potential.However,A current limitation lies in the absence of a comprehensive quantitative approach to assess the capabilities of LaWS.To address this issue,a damage effectiveness characterization model for LaWS is established,taking into account the properties of laser transmission through the atmosphere and the thermal damage effects.By employing this model,key parameters pertaining to the effectiveness of laser damage are determined.The impact of various spatial positions and atmospheric conditions on the damage effectiveness of LaWS have been examined,employing simulation experiments with diverse parameters.The conclusions indicate that the damage effectiveness of LaWS is contingent upon the spatial position of the target,resulting in a diminished effectiveness to damage on distant,low-altitude targets.Additionally,the damage effectiveness of LaWS is heavily reliant on the atmospheric condition,particularly in complex settings such as midday and low visibility conditions,where the damage effectiveness is substantially reduced.This paper provides an accurate and effective calculation method for the rapid decisionmaking of the operators.
基金funding by National Natural Science Foundation of China(No.52105137)the National Science and Technology Major Project,China(No.2017-IV0012-0049)the Beijing Natural Science Foundation,China(No.3244033)。
文摘A Combined Cycle Fatigue(CCF)life prediction model considering the effect of load sequence was proposed.To account for the interaction of high and low cycle fatigue,the CCF load was divided into two different loading paths of variable stress amplitude and stress ratio.Based on the iso-damage curves,a CCF life prediction model independent of fitting parameters was proposed,agreeing well with the experimental results.Finally,the effect of load sequence on CCF was discussed according to the fracture morphology of designed blade-like specimen.The results showed that the predicted CCF life was almost located in three-fold dispersion band for the LCF-HCF(LH)and HCF-LCF(HL)loading paths,especially for the average results of both.Compared with other models,the proposed model had better predictive and generalization abilities for multiple materials and variable experimental conditions.
基金supported by the National Natural Science Foundation of China(No.42107168).
文摘Aiming at challenges posed by rock freezethaw(FT)in cold regions rock mass engineering,it is of great significance to analyze its macro-and micromechanical properties and damage laws for the smooth progress of construction.In this study,indoor freezethaw cycle(FTC)tests on sandstone were conducted to analyze the mass change rate,density change rate,longitudinal wave velocity change rate,microstructure change and mechanical properties of sandstone after FTC.A microscopic FT damage variable reflecting the FT damage was defined based on the changes of rock porosity before and after the FTC,enabling the derivation of the total damage variable under the coupled action of FTC and mechanical loading.A damage evolution equation and a microscopic damage constitutive model for rock under coupled FTC and confining pressure were established by using Lemaitre’s strain equivalence principle,the theory of continuous damage mechanics,and the assumption that the failure of rock micro-units follows the SMP criterion.The rationality and accuracy of the model were verified using triaxial compression test data for FT-damaged rock.The results show that both macroand micro-mechanical properties of sandstone are degraded under the action of FTC,resulting in significant damage.The developed microscopic damage constitutive model can reflect the stress-strain characteristics of the whole process of FT rock triaxial compression,with excellent agreement observed between experimental and theoretical curves.This validates the reliability of the model and the methodology for determining its parameters.Additionally,defining the microscopic FT damage variable based on rock porosity changes is demonstrated to be a feasible and highly accurate approach to reflect rock FT damage degree.This model expands the damage model for rock under the coupling effect of FTC and confining pressure,further illuminating the damage mechanism and failure law in such environments.The findings provide references for the construction of rock mass engineering in cold regions.
基金support of the Natural Science Foundation of Shandong Province general project(ZR2022ME183)National Natural Science Foundation of China-General Project(52374215).
文摘Compared with blast mining only,blast mining after on-site hydraulic fracturing can make the mining easier and obtain better mining outcomes.To explore the effects of hydraulic fracturing on the blasting damages in coal seam,blasting experiments were carried out under biaxial confining pressure using the synthetic coal briquettes.The coal briquettes with the same mechanical properties as coal seam were prepared and the mica sheets with different radi and thicknesses were added to simulate the internal hydraulic fractures of different radi and openings.The internal damage distributions and stress attenuations of the coal briquette specimens with different hydraulic fracture radi and openings after the blasting were then measured using a rock ultrasonic tester and a static-dynamic strainmeter.Based on the rock blasting theory,the effects of hydraulic fractures with different radi and openings on the blast fracture propagation and coal seam damage were analyzed.The following conclusions are drawn:(1)The increases in hydraulic fracture radius mainly enhance the damages in the vertical direction to the hydraulic fracture,and can increase the vertical range of the severely damaged area by 20-25 cm.The increases in the hydraulic fracture opening mainly cause more severe damages along the direction of the hydraulic fracture and increase the horizontal range of the severely damaged area by 30 cm.(2)The area of the severely damaged area caused by blasting increases by 550 cm?as the hydraulic fracture radius increased from 5 to 15 cm.As the hydraulic fracture opening increased from 2 to 10 mm,and the area of the severely damaged area caused by blasting increases by 650 cm?.Therefore,the hydraulic fracture opening has greater impacts on the severely damaged area.(3)The increase in the hydraulic fracture length reduces the compression phase attenuation of the blast stress in the radial direction.Both the increases of the hydraulic fracture length and opening increase the absolute value of the tensile phase in the radial direction.(4)Increasing the hydraulic fracture radius and opening can greatly promote the development of blast fractures and enhance the damages to coal seam.Therefore,the coal seam mining effect can be improved by increasing the radi or openings of hydraulic fractures to adjust the main action direction of blast fracture.
基金supported by the National Natural Science Foundation of China(32071240,82373526).
文摘Small nucleolar RNAs(snoRNAs)were previously regarded as a class of functionally conserved housekeeping genes,primarily involved in the regulation of ribosome biogenesis by ribosomal RNA(rRNA)modification.However,some of them are involved in several biological processes via complex molecular mechanisms.DNA damage response(DDR)is a conserved mechanism for maintaining genomic stability to prevent the occurrence of various human diseases.It has recently been revealed that snoRNAs are involved in DDR at multiple levels,indicating their relevant theoretical and clinical significance in this field.The present review systematically addresses four main points,including the biosynthesis and classification of snoRNAs,the mechanisms through which snoRNAs regulate target molecules,snoRNAs in the process of DDR,and the significance of snoRNA in disease diagnosis and treatment.It focuses on the potential functions of snoRNAs in DDR to help in the discovery of the roles of snoRNAs in maintaining genome stability and pathological processes.
