The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained expe...The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.展开更多
A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states...A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.展开更多
The catalytic oxidation of HMF involves a cascading reaction with multiple intermediate products,making it crucial to enhance the oriented adsorption capacity of specific functional groups for accelerating the entire ...The catalytic oxidation of HMF involves a cascading reaction with multiple intermediate products,making it crucial to enhance the oriented adsorption capacity of specific functional groups for accelerating the entire process.To achieve the efficient selective oxidation of HMF to FDCA,a series of NiCo_(2)O_(4)catalysts with different morphologies,such as flaky,echinoids,pompon and corolla,were prepared and characterized by XRD,SEM,TEM,BET,XPS,and FTIR.Among the four catalysts,flaky NiCo_(2)O_(4)exhibited the most excellent catalytic activity and stability,with a FDCA yield of 60.1%within 12 h at 80℃without alkali participation.The excellent performance of flaky NiCo_(2)O_(4)catalyst is attributed to the oxygen vacancies and acid sites generated by the exposed(400)facets.The oxygen vacancies and acid sites on the catalyst surface can precisely adsorb-CHO and-CH_(2)-OH of HMF,respectively,and this synergistic effect promotes the efficient production of FDCA.This work is of great significance for fundamentally study the effect of micro-topography or crystal-plane reaction properties on surfaces.展开更多
BACKGROUND The dexmedetomidine(DEX)plus ropivacaine treatment enables a transversus abdominis plane block(TAPB)of the peripheral nerves in patients undergoing radical resection for colorectal cancer(CRC)that can provi...BACKGROUND The dexmedetomidine(DEX)plus ropivacaine treatment enables a transversus abdominis plane block(TAPB)of the peripheral nerves in patients undergoing radical resection for colorectal cancer(CRC)that can provide clinical data for improving the postoperative analgesic effect,reducing the risk of cognitive impairment,and decreasing the circulating levels of serum inflammatory factors and stress hormones.AIM To assess the impact of DEX plus ropivacaine-enabled TAPB on pain,postoperative cognitive dysfunction(POCD),and inflammatory/stress factors.METHODS Our patient cohort was randomly divided into control and observation groups(60/group).The observation group used a DEX plus ropivacaine-enabled TAPB,while the control group employed a ropivacaine-enabled TAPB.The pain score[Visual Analogy Scale(VAS),Montreal Cognitive Assessment(MoCA)],serum inflammatory factor level(C-reactive protein,interleukin-6 and tumor necrosis factor-α),serum stress hormone levels(cortisol and adrenaline)and postoperative adverse reactions were compared between the two groups.RESULTS The observation group VAS scores were lower than those of the control group(better analgesic effect,P<0.05).The MoCA and POCD scores decreased post-surgery in the observation group(P<0.05).In the elderly,the overall VAS and MoCA scores were significantly reduced compared with the young group.The C-reactive protein,interleukin-6,tumor necrosis factor-α,cortisol and adrenaline levels were lower in the observation group compared with the control group post-surgery(P<0.05).There was no significant difference in adverse reactions between the two groups post-surgery,but the incidence of adverse reactions in the observation group was still lower.DEX continuously inhibited p65-phosphorylation levels in the nuclear factorκB pathway at multiple time points,and its inhibitory effect became more significant over time.CONCLUSION DEX plus ropivacaine-enabled TAPB reduces POCD and inflammatory/stress hormone levels,and significantly improves the postoperative analgesic effect of patients undergoing radical resection for colorectal cancer.展开更多
In this paper,we establish a stability estimate for the isoperimetric inequality of horospherically convex domains in hyperbolic plane.This estimate involves a relationship between the Hausdorff distance to a geodesic...In this paper,we establish a stability estimate for the isoperimetric inequality of horospherically convex domains in hyperbolic plane.This estimate involves a relationship between the Hausdorff distance to a geodesic ball and the deficit in the isoperimetric inequality,where the coefficient of the deficit is a universal constant.展开更多
The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compr...The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compression.While previous studies focused on the angleβbetween the maximum principal stress and the structural plane,the role of angleω,between the intermediate principal stress and the structural plane,is often overlooked.Utilizing artificially prefabricated granite specimens with a single non-penetrating structural plane,we set the loading angleβto range from 0°to 90°across seven groups,and assignedωvalues of 0°and 90°in two separate groups.The results show that the peak strength is negatively correlated withβup to 45°,beyond which it tends to stabilize.The angleωexerts a strengthening effect on the peak strength.Deformation mainly occurs post-peak,with the strain values ε_(1) and ε_(3) reaching levels 2−3 times higher than those in intact rock.The structural plane significantly influences failure mode whenω=0°,while failure localizes near the σ_(3) surface of the specimens whenω=90°.The findings enhance data on structural plane rocks under triaxial compression and inform theoretical research,excavation,and support design of rock structures.展开更多
Breast augmentation with implants is a popular cosmetic surgery that enhances breast volume and contour through various placement planes.In this review,we examine the impact of subglandular,subpectoral,and subfascial ...Breast augmentation with implants is a popular cosmetic surgery that enhances breast volume and contour through various placement planes.In this review,we examine the impact of subglandular,subpectoral,and subfascial implant planes on postoperative outcomes and complication rates.Subglandular placement offers simplicity but is associated with higher risks of capsular contracture,hematoma,and rippling in patients with low tissue coverage.The subpectoral plane,widely adopted for its natural appearance and reduced capsular contracture risk,may cause dynamic deformity due to muscle contraction.Although technically challenging,the subfascial plane combines the benefits of soft tissue support and reduced implant displacement.We highlight the importance of choosing an optimal implant plane tailored to each patient’s anatomical and aesthetic needs to enhance surgical outcomes and minimize complications.Further research is needed to validate long-term efficacy,particularly for subfascial placement.展开更多
A solution for the lithospheric deformation of a uniform,elastically isotropic layer(EIL)of uniform thickness welded with a uniform,elastically orthotropic half-space(EOHS)due to a vertical tensile line fault(VTLF)wit...A solution for the lithospheric deformation of a uniform,elastically isotropic layer(EIL)of uniform thickness welded with a uniform,elastically orthotropic half-space(EOHS)due to a vertical tensile line fault(VTLF)with an opening in the horizontal direction located in the isotropic layer is derived in the integral form by employing Airy’s stress function approach for the plane strain case.The linear combination of exponential terms appearing in the denominator of the integral expressions of the deformation field of the EIL is expressed as a finite sum of exponential terms(FSET)by applying the method of least squares to analytically compute the deformation field.The displacement field is discussed in detail and computed numerically by considering the EOHS as olivine or barytes material or considering half-space to be isotropic.展开更多
In recent years,the world has seen an exponential increase in energy demand,prompting scientists to look for innovative ways to exploit the power sun’s power.Solar energy technologies use the sun’s energy and light ...In recent years,the world has seen an exponential increase in energy demand,prompting scientists to look for innovative ways to exploit the power sun’s power.Solar energy technologies use the sun’s energy and light to provide heating,lighting,hot water,electricity and even cooling for homes,businesses,and industries.Therefore,ground-level solar radiation data is important for these applications.Thus,our work aims to use a mathematical modeling tool to predict solar irradiation.For this purpose,we are interested in the application of the Adaptive Neuro Fuzzy Inference System.Through this type of artificial neural system,10 models were developed,based on meteorological data such as the Day number(Nj),Ambient temperature(T),Relative Humidity(Hr),Wind speed(WS),Wind direction(WD),Declination(δ),Irradiation outside the atmosphere(Goh),Maximum temperature(Tmax),Minimum temperature(Tmin).These models have been tested by different static indicators to choose the most suitable one for the estimation of the daily global solar radiation.This study led us to choose the M8 model,which takes Nj,T,Hr,δ,Ws,Wd,G0,and S0 as input variables because it presents the best performance either in the learning phase(R^(2)=0.981,RMSE=0.107 kW/m^(2),MAE=0.089 kW/m2)or in the validation phase(R^(2)=0.979,RMSE=0.117 kW/m^(2),MAE=0.101 kW/m^(2)).展开更多
Oxygen evolution reaction(OER) is one of the most important half-reactions related to metal-air batteries,fuel cells, and water-splitting. Due to the sluggish kinetic and multi-electron transfer, catalysts appear to b...Oxygen evolution reaction(OER) is one of the most important half-reactions related to metal-air batteries,fuel cells, and water-splitting. Due to the sluggish kinetic and multi-electron transfer, catalysts appear to be particularly important for the OER. Knowing the reaction mechanism is fundamental to developing new catalysts and improving OER efficiency. In this work, phase transition and atomic reconstruction on Co O(111) plane were revealed through ex-situ diffraction methods and X-ray absorption spectroscopy.At the same time, the electronic state evolution of Co(Ⅱ)/Co(Ⅲ) during the OER process has also been concluded by analyzing the magnetic properties. This work shows that during the OER process, Co(Ⅲ)experiences surface electron rearrangement from IS(intermediate-spin state) to LS(low-spin state) and then returns to IS/HS(high-spin state) under high voltage region. This work provides a new view to reveal the reaction mechanism through the magnetic property and it can be extended to more magnetic 3d transition metals for future catalyst design.展开更多
1 Introduction In highway construction,flled embankments are trapezoidal,and the ground is always improved by sand wells or columns.During embankment construction,because the width and height of the embankment are cha...1 Introduction In highway construction,flled embankments are trapezoidal,and the ground is always improved by sand wells or columns.During embankment construction,because the width and height of the embankment are changing,a non-uniform load that varies with time and lateral location is applied to the underlying ground.The consolidation phenomenon under two-dimensional(2D)conditions will keep pace with the construction of the embankment.In addition,because of evaporation and rainfall,the soils are mostly unsaturated.Therefore,it is meaningful to research the consolidation properties of unsaturated ground under non-uniform loading.展开更多
During strike-slip fault dislocation,multiple fault planes are commonly observed.The resulting permanent ground deformation can lead to profound structural damage to tunnels.However,existing analytical models do not c...During strike-slip fault dislocation,multiple fault planes are commonly observed.The resulting permanent ground deformation can lead to profound structural damage to tunnels.However,existing analytical models do not consider multiple fault planes.Instead,they concentrate the entire fault displacement onto a single fault plane for analysis,thereby giving rise to notable errors in the calculated results.To address this issue,a refined nonlinear theoretical model was established to analyze the mechanical responses of the tunnels subjected to multiple strike-slip fault dislocations.The analytical model considers the number of fault planes,nonlinear soil‒tunnel interactions,geometric nonlinearity,and fault zone width,leading to a significant improvement in its range of applicability and calculation accuracy.The results of the analytical model are in agreement,both qualitatively and quantitatively,with the model test and numerical results.Then,based on the proposed theoretical model,a sensitivity analysis of parameters was conducted,focusing on the variables such as the number of fault planes,fault plane distance(d),fault displacement ratio(η),burial depth(C),crossing angle(β),tunnel diameter(D),fault zone width(Wf),and strike-slip fault displacement(Δfs).The results show that the peak shear force(Vmax),bending moment(Mmax),and axial force(Nmax)decrease with increasing d.The Vmax of the tunnel is found at the fault plane with the largest fault displacement.C,D,andΔfs contribute to the increases in Vmax,Mmax,and Nmax.Additionally,increasing the number of fault planes reduces Vmax and Mmax,whereas the variation in Nmax remains minimal.展开更多
Extremely large-scale array(XL-array)communications can significantly improve the transmission rate,spectral efficiency,and spatial resolution,and has great potential in next-generation mobile communication networks.A...Extremely large-scale array(XL-array)communications can significantly improve the transmission rate,spectral efficiency,and spatial resolution,and has great potential in next-generation mobile communication networks.A crucial problem in XLarray communications is to determine the boundary of applicable regions of the plane wave model(PWM)and spherical wave model(SWM).In this paper,we propose new PWM/SWM demarcations for XL-arrays from the viewpoint of channel gain and rank.Four sets of results are derived for four different array setups.First,an equi-power line is derived for a point-touniform linear array(ULA)scenario,where an inflection point is found at±π6 central incident angles.Second,an equi-power surface is derived for a point-touniform planar array(UPA)scenario,and it is proved that cos2(ϕ)cos2(φ)=12 is a dividing curve,where ϕ andφdenote the elevation and azimuth angles,respectively.Third,an accurate and explicit expression of the equi-rank surface is obtained for a ULA-to-ULA scenario.Finally,an approximated expression of the equirank surface is obtained for a ULA-to-UPA scenario.With the obtained closed-form expressions,the equirank surface for any antenna structure and any angle can be well estimated.Furthermore,the effect of scatterers is also investigated,from which some insights are drawn.展开更多
Anti-phase domain defects easily form in the in-plane GaAs nanowires(NWs)grown on CMOS-compatiblegroup IV substrates,which makes it difficult to obtain GaAs NWs with a designed length and also leads to asignificant li...Anti-phase domain defects easily form in the in-plane GaAs nanowires(NWs)grown on CMOS-compatiblegroup IV substrates,which makes it difficult to obtain GaAs NWs with a designed length and also leads to asignificant limitation in the growth of high-quality in-plane GaAs NW networks on such substrates.Here,wereport on the selective area growth of anti-phase domain-free in-plane GaAs NWs and NW networks on Ge(111)substrates.Detailed structural studies confirm that the GaAs NW grown using a large pattern period and GaAsNW networks grown by adding the Sb are both high-quality pure zinc-blende single crystals free of stackingfaults,twin defects,and anti-phase domain defects.Room-temperature photoluminescence measurements show asubstantial improvement in crystal quality and good consistency and uniformity of the GaAs NW networks.Ourwork provides useful insights into the controlled growth of high-quality anti-phase domain-defects-free in-planeIII-V NWs and NW networks.展开更多
As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canist...As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.展开更多
The rock mass consists of rock blocks and structural planes,which can reduce its integrity and strength.Therefore,accurately obtaining the characteristics of the rock mass structural plane is a prerequisite for evalua...The rock mass consists of rock blocks and structural planes,which can reduce its integrity and strength.Therefore,accurately obtaining the characteristics of the rock mass structural plane is a prerequisite for evaluating stability and designing supports in underground engineering.Currently,there are no effective testing methods for the characteristic parameters of the rock mass structural plane in underground engineering.The paper presents the digital drilling technology as a new testing method of rock mass structural planes.Flawed rock specimens with cracks of varying widths and angles were used to simulate the rock mass structural planes,and the multifunctional rock mass digital drilling test system was employed to carry out the digital drilling tests.The analysis focuses on the variation laws of drilling parameters,such as drilling pressure and drilling torque,affected by the characteristics of prefabricated cracks,and clarifies the degradation mechanism of rock equivalent compressive strength.Additionally,an identification model for the characteristic parameters of rock mass structural planes during drilling is established.The test results indicate that the average difference of the characteristics of prefabricated cracks identified by the equivalent compressive strength is 2.45°and 0.82 mm,respectively.The identification model while drilling is verified to be correct due to the high identification accuracy.Based on this,a method for testing the characteristic parameters of the surrounding rock structural plane while drilling is proposed.The research offers a theoretical and methodological foundation for precise in situ identification of structural planes of the surrounding rock in underground engineering.展开更多
Laparoscopic surgery is the main treatment method for patients with gastrointestinal malignant tumors.Although laparoscopic surgery is minimally invasive,its tool stimulation and pneumoperitoneum pressure often cause ...Laparoscopic surgery is the main treatment method for patients with gastrointestinal malignant tumors.Although laparoscopic surgery is minimally invasive,its tool stimulation and pneumoperitoneum pressure often cause strong stress reactions in patients.On the other hand,gastrointestinal surgery can cause stronger pain in patients,compared to other surgeries.Transversus abdominis plane block(TAPB)can effectively inhibit the transmission of nerve impulses caused by surgical stimulation,alleviate patient pain,and thus alleviate stress reactions.Remazolam is an acting,safe,and effective sedative,which has little effect on hemodynamics and is suitable for most patients.TAPB combined with remazolam can reduce the dosage of total anesthetic drugs,reduce adverse reactions,reduce stress reactions,and facilitate the rapid postoperative recovery of patients.展开更多
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 ...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.展开更多
A nuclear explosion in the rock mass medium can produce strong shock waves,seismic shocks,and other destructive effects,which can cause extreme damage to the underground protection infrastructures.With the increase in...A nuclear explosion in the rock mass medium can produce strong shock waves,seismic shocks,and other destructive effects,which can cause extreme damage to the underground protection infrastructures.With the increase in nuclear explosion power,underground protection engineering enabled by explosion-proof impact theory and technology ushered in a new challenge.This paper proposes to simulate nuclear explosion tests with on-site chemical explosion tests in the form of multi-hole explosions.First,the mechanism of using multi-hole simultaneous blasting to simulate a nuclear explosion to generate approximate plane waves was analyzed.The plane pressure curve at the vault of the underground protective tunnel under the action of the multi-hole simultaneous blasting was then obtained using the impact test in the rock mass at the site.According to the peak pressure at the vault plane,it was divided into three regions:the stress superposition region,the superposition region after surface reflection,and the approximate plane stress wave zone.A numerical simulation approach was developed using PFC and FLAC to study the peak particle velocity in the surrounding rock of the underground protective cave under the action of multi-hole blasting.The time-history curves of pressure and peak pressure partition obtained by the on-site multi-hole simultaneous blasting test and numerical simulation were compared and analyzed,to verify the correctness and rationality of the formation of an approximate plane wave in the simulated nuclear explosion.This comparison and analysis also provided a theoretical foundation and some research ideas for the ensuing study on the impact of a nuclear explosion.展开更多
文摘The prediction of the fracture plane orientation in fatigue is a scientific topic and remains relevant for every type of material. However, in this work, we compared the orientation of the fracture plane obtained experimentally through tests on specimens under multiaxial loading with that calculated by the variance method. In the statistical approach criteria, several methods have been developed but we have presented only one method, namely the variance method using the equivalent stress. She assumes that the fracture plane orientation is the one on which the variance of the equivalent stress is maximum. Three types of equivalent stress are defined for this method [1]: normal stress, shear stress and combined normal and shear stress. The results obtained were compared with experimental results for multiaxial cyclic stress states, and it emerges that the variance method for the case of combined loading is conservative as it gives a better prediction of the fracture plane.
基金supports from the National Natural Science Foundation of China (Grant Nos.52004143 and 52374095)the open fund for the Laboratory of Mining Response and Disaster Prevention and Control in Deep Coal Mines (Grant No.SKLMRDPC21KF06).
文摘A series of true triaxial unloading tests are conducted on sandstone specimens with a single structural plane to investigate their mechanical behaviors and failure characteristics under different in situ stress states.The experimental results indicate that the dip angle of structural plane(θ)and the intermediate principal stress(σ2)have an important influence on the peak strength,cracking mode,and rockburst severity.The peak strength exhibits a first increase and then decrease as a function ofσ2 for a constantθ.However,whenσ2 is constant,the maximum peak strength is obtained atθof 90°,and the minimum peak strength is obtained atθof 30°or 45°.For the case of an inclined structural plane,the crack type at the tips of structural plane transforms from a mix of wing and anti-wing cracks to wing cracks with an increase inσ2,while the crack type around the tips of structural plane is always anti-wing cracks for the vertical structural plane,accompanied by a series of tensile cracks besides.The specimens with structural plane do not undergo slabbing failure regardless ofθ,and always exhibit composite tensile-shear failure whatever theσ2 value is.With an increase inσ2 andθ,the intensity of the rockburst is consistent with the tendency of the peak strength.By analyzing the relationship between the cohesion(c),internal friction angle(φ),andθin sandstone specimens,we incorporateθinto the true triaxial unloading strength criterion,and propose a modified linear Mogi-Coulomb criterion.Moreover,the crack propagation mechanism at the tips of structural plane,and closure degree of the structural plane under true triaxial unloading conditions are also discussed and summarized.This study provides theoretical guidance for stability assessment of surrounding rocks containing geological structures in deep complex stress environments.
基金supported by the Swedish Energy Agency(P47500-1)the National Key R&D Program of China(2020YFA0710200)+2 种基金the National Natural Science Foundation of China(22378401 and U22A20416)the financial support from STINT(CH2019-8287)financial support from the European Union and Swedish Energy Agency(P2020-90066).
文摘The catalytic oxidation of HMF involves a cascading reaction with multiple intermediate products,making it crucial to enhance the oriented adsorption capacity of specific functional groups for accelerating the entire process.To achieve the efficient selective oxidation of HMF to FDCA,a series of NiCo_(2)O_(4)catalysts with different morphologies,such as flaky,echinoids,pompon and corolla,were prepared and characterized by XRD,SEM,TEM,BET,XPS,and FTIR.Among the four catalysts,flaky NiCo_(2)O_(4)exhibited the most excellent catalytic activity and stability,with a FDCA yield of 60.1%within 12 h at 80℃without alkali participation.The excellent performance of flaky NiCo_(2)O_(4)catalyst is attributed to the oxygen vacancies and acid sites generated by the exposed(400)facets.The oxygen vacancies and acid sites on the catalyst surface can precisely adsorb-CHO and-CH_(2)-OH of HMF,respectively,and this synergistic effect promotes the efficient production of FDCA.This work is of great significance for fundamentally study the effect of micro-topography or crystal-plane reaction properties on surfaces.
文摘BACKGROUND The dexmedetomidine(DEX)plus ropivacaine treatment enables a transversus abdominis plane block(TAPB)of the peripheral nerves in patients undergoing radical resection for colorectal cancer(CRC)that can provide clinical data for improving the postoperative analgesic effect,reducing the risk of cognitive impairment,and decreasing the circulating levels of serum inflammatory factors and stress hormones.AIM To assess the impact of DEX plus ropivacaine-enabled TAPB on pain,postoperative cognitive dysfunction(POCD),and inflammatory/stress factors.METHODS Our patient cohort was randomly divided into control and observation groups(60/group).The observation group used a DEX plus ropivacaine-enabled TAPB,while the control group employed a ropivacaine-enabled TAPB.The pain score[Visual Analogy Scale(VAS),Montreal Cognitive Assessment(MoCA)],serum inflammatory factor level(C-reactive protein,interleukin-6 and tumor necrosis factor-α),serum stress hormone levels(cortisol and adrenaline)and postoperative adverse reactions were compared between the two groups.RESULTS The observation group VAS scores were lower than those of the control group(better analgesic effect,P<0.05).The MoCA and POCD scores decreased post-surgery in the observation group(P<0.05).In the elderly,the overall VAS and MoCA scores were significantly reduced compared with the young group.The C-reactive protein,interleukin-6,tumor necrosis factor-α,cortisol and adrenaline levels were lower in the observation group compared with the control group post-surgery(P<0.05).There was no significant difference in adverse reactions between the two groups post-surgery,but the incidence of adverse reactions in the observation group was still lower.DEX continuously inhibited p65-phosphorylation levels in the nuclear factorκB pathway at multiple time points,and its inhibitory effect became more significant over time.CONCLUSION DEX plus ropivacaine-enabled TAPB reduces POCD and inflammatory/stress hormone levels,and significantly improves the postoperative analgesic effect of patients undergoing radical resection for colorectal cancer.
文摘In this paper,we establish a stability estimate for the isoperimetric inequality of horospherically convex domains in hyperbolic plane.This estimate involves a relationship between the Hausdorff distance to a geodesic ball and the deficit in the isoperimetric inequality,where the coefficient of the deficit is a universal constant.
基金Projects(51979268,52279117,52309146)supported by the National Natural Science Foundation of ChinaProject(SKLGME-JBGS2401)supported by the Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering,China。
文摘The spatial relationship between structural planes and principal stresses significantly affects the mechanical properties of deep hard rock.This paper examines the effect of the loading angle under true triaxial compression.While previous studies focused on the angleβbetween the maximum principal stress and the structural plane,the role of angleω,between the intermediate principal stress and the structural plane,is often overlooked.Utilizing artificially prefabricated granite specimens with a single non-penetrating structural plane,we set the loading angleβto range from 0°to 90°across seven groups,and assignedωvalues of 0°and 90°in two separate groups.The results show that the peak strength is negatively correlated withβup to 45°,beyond which it tends to stabilize.The angleωexerts a strengthening effect on the peak strength.Deformation mainly occurs post-peak,with the strain values ε_(1) and ε_(3) reaching levels 2−3 times higher than those in intact rock.The structural plane significantly influences failure mode whenω=0°,while failure localizes near the σ_(3) surface of the specimens whenω=90°.The findings enhance data on structural plane rocks under triaxial compression and inform theoretical research,excavation,and support design of rock structures.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(grant no.LQ22H150005).
文摘Breast augmentation with implants is a popular cosmetic surgery that enhances breast volume and contour through various placement planes.In this review,we examine the impact of subglandular,subpectoral,and subfascial implant planes on postoperative outcomes and complication rates.Subglandular placement offers simplicity but is associated with higher risks of capsular contracture,hematoma,and rippling in patients with low tissue coverage.The subpectoral plane,widely adopted for its natural appearance and reduced capsular contracture risk,may cause dynamic deformity due to muscle contraction.Although technically challenging,the subfascial plane combines the benefits of soft tissue support and reduced implant displacement.We highlight the importance of choosing an optimal implant plane tailored to each patient’s anatomical and aesthetic needs to enhance surgical outcomes and minimize complications.Further research is needed to validate long-term efficacy,particularly for subfascial placement.
文摘A solution for the lithospheric deformation of a uniform,elastically isotropic layer(EIL)of uniform thickness welded with a uniform,elastically orthotropic half-space(EOHS)due to a vertical tensile line fault(VTLF)with an opening in the horizontal direction located in the isotropic layer is derived in the integral form by employing Airy’s stress function approach for the plane strain case.The linear combination of exponential terms appearing in the denominator of the integral expressions of the deformation field of the EIL is expressed as a finite sum of exponential terms(FSET)by applying the method of least squares to analytically compute the deformation field.The displacement field is discussed in detail and computed numerically by considering the EOHS as olivine or barytes material or considering half-space to be isotropic.
文摘In recent years,the world has seen an exponential increase in energy demand,prompting scientists to look for innovative ways to exploit the power sun’s power.Solar energy technologies use the sun’s energy and light to provide heating,lighting,hot water,electricity and even cooling for homes,businesses,and industries.Therefore,ground-level solar radiation data is important for these applications.Thus,our work aims to use a mathematical modeling tool to predict solar irradiation.For this purpose,we are interested in the application of the Adaptive Neuro Fuzzy Inference System.Through this type of artificial neural system,10 models were developed,based on meteorological data such as the Day number(Nj),Ambient temperature(T),Relative Humidity(Hr),Wind speed(WS),Wind direction(WD),Declination(δ),Irradiation outside the atmosphere(Goh),Maximum temperature(Tmax),Minimum temperature(Tmin).These models have been tested by different static indicators to choose the most suitable one for the estimation of the daily global solar radiation.This study led us to choose the M8 model,which takes Nj,T,Hr,δ,Ws,Wd,G0,and S0 as input variables because it presents the best performance either in the learning phase(R^(2)=0.981,RMSE=0.107 kW/m^(2),MAE=0.089 kW/m2)or in the validation phase(R^(2)=0.979,RMSE=0.117 kW/m^(2),MAE=0.101 kW/m^(2)).
基金financially supported by the National Natural Science Foundation of China(No.52171210)the Program for the Development of Science and Technology of Jilin Province(Nos.20240101004JC,20220201130GX,and 20240402072GH)。
文摘Oxygen evolution reaction(OER) is one of the most important half-reactions related to metal-air batteries,fuel cells, and water-splitting. Due to the sluggish kinetic and multi-electron transfer, catalysts appear to be particularly important for the OER. Knowing the reaction mechanism is fundamental to developing new catalysts and improving OER efficiency. In this work, phase transition and atomic reconstruction on Co O(111) plane were revealed through ex-situ diffraction methods and X-ray absorption spectroscopy.At the same time, the electronic state evolution of Co(Ⅱ)/Co(Ⅲ) during the OER process has also been concluded by analyzing the magnetic properties. This work shows that during the OER process, Co(Ⅲ)experiences surface electron rearrangement from IS(intermediate-spin state) to LS(low-spin state) and then returns to IS/HS(high-spin state) under high voltage region. This work provides a new view to reveal the reaction mechanism through the magnetic property and it can be extended to more magnetic 3d transition metals for future catalyst design.
基金supported by the National Nature Science Foundation of China(No.12172211)the National Key Research and Development Program of China(No.2019YFC1509800)。
文摘1 Introduction In highway construction,flled embankments are trapezoidal,and the ground is always improved by sand wells or columns.During embankment construction,because the width and height of the embankment are changing,a non-uniform load that varies with time and lateral location is applied to the underlying ground.The consolidation phenomenon under two-dimensional(2D)conditions will keep pace with the construction of the embankment.In addition,because of evaporation and rainfall,the soils are mostly unsaturated.Therefore,it is meaningful to research the consolidation properties of unsaturated ground under non-uniform loading.
基金support from the National Natural Science Foundation of China(Grant Nos.52378411,52208404)China National Railway Group Limited Science and Technology Research and Development Program(Grant No.K2023G041).
文摘During strike-slip fault dislocation,multiple fault planes are commonly observed.The resulting permanent ground deformation can lead to profound structural damage to tunnels.However,existing analytical models do not consider multiple fault planes.Instead,they concentrate the entire fault displacement onto a single fault plane for analysis,thereby giving rise to notable errors in the calculated results.To address this issue,a refined nonlinear theoretical model was established to analyze the mechanical responses of the tunnels subjected to multiple strike-slip fault dislocations.The analytical model considers the number of fault planes,nonlinear soil‒tunnel interactions,geometric nonlinearity,and fault zone width,leading to a significant improvement in its range of applicability and calculation accuracy.The results of the analytical model are in agreement,both qualitatively and quantitatively,with the model test and numerical results.Then,based on the proposed theoretical model,a sensitivity analysis of parameters was conducted,focusing on the variables such as the number of fault planes,fault plane distance(d),fault displacement ratio(η),burial depth(C),crossing angle(β),tunnel diameter(D),fault zone width(Wf),and strike-slip fault displacement(Δfs).The results show that the peak shear force(Vmax),bending moment(Mmax),and axial force(Nmax)decrease with increasing d.The Vmax of the tunnel is found at the fault plane with the largest fault displacement.C,D,andΔfs contribute to the increases in Vmax,Mmax,and Nmax.Additionally,increasing the number of fault planes reduces Vmax and Mmax,whereas the variation in Nmax remains minimal.
基金supported in part by the National Natural Science Foundation of China (NSFC) under Grants 62271310 and 62125108in part by the Fundamental Research Funds for the Central Universities of Chinain part by the NSFC under Grant 62431014
文摘Extremely large-scale array(XL-array)communications can significantly improve the transmission rate,spectral efficiency,and spatial resolution,and has great potential in next-generation mobile communication networks.A crucial problem in XLarray communications is to determine the boundary of applicable regions of the plane wave model(PWM)and spherical wave model(SWM).In this paper,we propose new PWM/SWM demarcations for XL-arrays from the viewpoint of channel gain and rank.Four sets of results are derived for four different array setups.First,an equi-power line is derived for a point-touniform linear array(ULA)scenario,where an inflection point is found at±π6 central incident angles.Second,an equi-power surface is derived for a point-touniform planar array(UPA)scenario,and it is proved that cos2(ϕ)cos2(φ)=12 is a dividing curve,where ϕ andφdenote the elevation and azimuth angles,respectively.Third,an accurate and explicit expression of the equi-rank surface is obtained for a ULA-to-ULA scenario.Finally,an approximated expression of the equirank surface is obtained for a ULA-to-UPA scenario.With the obtained closed-form expressions,the equirank surface for any antenna structure and any angle can be well estimated.Furthermore,the effect of scatterers is also investigated,from which some insights are drawn.
基金supported by the National Natural Science Foundation of China(Grant Nos.12374459,61974138,and 92065106)the Innovation Program for Quantum Science and Technology(Grant No.2021ZD0302400)+1 种基金the Strategic Priority Research Program of Chinese Academy of Sciences(Grant No.XDB0460000)the support from the Youth Innovation Promotion Association,Chinese Academy of Sciences(Grant Nos.2017156 and Y2021043)。
文摘Anti-phase domain defects easily form in the in-plane GaAs nanowires(NWs)grown on CMOS-compatiblegroup IV substrates,which makes it difficult to obtain GaAs NWs with a designed length and also leads to asignificant limitation in the growth of high-quality in-plane GaAs NW networks on such substrates.Here,wereport on the selective area growth of anti-phase domain-free in-plane GaAs NWs and NW networks on Ge(111)substrates.Detailed structural studies confirm that the GaAs NW grown using a large pattern period and GaAsNW networks grown by adding the Sb are both high-quality pure zinc-blende single crystals free of stackingfaults,twin defects,and anti-phase domain defects.Room-temperature photoluminescence measurements show asubstantial improvement in crystal quality and good consistency and uniformity of the GaAs NW networks.Ourwork provides useful insights into the controlled growth of high-quality anti-phase domain-defects-free in-planeIII-V NWs and NW networks.
基金supported by National Natural Science Foundation of China(Grant No.92266201).
文摘As the performance of the box-type multiple launch rocket system(BMLRS)improves,its mechanical structures,particularly the plane clearance design between the slider on the rocket and the guide inside the launch canister,have grown increasingly complex.However,deficiencies still exist in the current launch modeling theory for BMLRS.In this study,a multi-rigid-flexible-body launch dynamics model coupling the launch platform and rocket was established using the multibody system transfer matrix method and the Newton-Euler formulation.Furthermore,considering the bending of the launch canister,a detection algorithm for slider-guide plane clearance contact was proposed.To quantify the contact force and friction effect between the slider and guide,the contact force model and modified Coulomb model were introduced.Both the modal and launch tests were conducted.Additionally,the modal convergence was verified.By comparing the modal experiments and simulation results,the maximum relative error of the eigenfrequency is 3.29%.thereby verifying the accuracy of the developed BMLRS dynamics model.Furthermore,the launch test validated the proposed plane clearance contact model.Moreover,the study investigated the influence of various model parameters on the dynamic characteristics of BMLRS,including launch canister bending stiffness,slider and guide material,slider-guide clearance,slider length and layout.This analysis of influencing factors provides a foundation for future optimization in BMLRS design.
基金supported by the National Key Research and Development Program of China(Grant No.2023YFC2907600)the National Natural Science Foundation of China(Grant Nos.42277174 and 52204260).
文摘The rock mass consists of rock blocks and structural planes,which can reduce its integrity and strength.Therefore,accurately obtaining the characteristics of the rock mass structural plane is a prerequisite for evaluating stability and designing supports in underground engineering.Currently,there are no effective testing methods for the characteristic parameters of the rock mass structural plane in underground engineering.The paper presents the digital drilling technology as a new testing method of rock mass structural planes.Flawed rock specimens with cracks of varying widths and angles were used to simulate the rock mass structural planes,and the multifunctional rock mass digital drilling test system was employed to carry out the digital drilling tests.The analysis focuses on the variation laws of drilling parameters,such as drilling pressure and drilling torque,affected by the characteristics of prefabricated cracks,and clarifies the degradation mechanism of rock equivalent compressive strength.Additionally,an identification model for the characteristic parameters of rock mass structural planes during drilling is established.The test results indicate that the average difference of the characteristics of prefabricated cracks identified by the equivalent compressive strength is 2.45°and 0.82 mm,respectively.The identification model while drilling is verified to be correct due to the high identification accuracy.Based on this,a method for testing the characteristic parameters of the surrounding rock structural plane while drilling is proposed.The research offers a theoretical and methodological foundation for precise in situ identification of structural planes of the surrounding rock in underground engineering.
基金Supported by Health Commission of Hebei Province,China,No.20240074Scientific Research Project of Hebei Provincial Administration of Traditional Chinese Medicine,China,No.2024317.
文摘Laparoscopic surgery is the main treatment method for patients with gastrointestinal malignant tumors.Although laparoscopic surgery is minimally invasive,its tool stimulation and pneumoperitoneum pressure often cause strong stress reactions in patients.On the other hand,gastrointestinal surgery can cause stronger pain in patients,compared to other surgeries.Transversus abdominis plane block(TAPB)can effectively inhibit the transmission of nerve impulses caused by surgical stimulation,alleviate patient pain,and thus alleviate stress reactions.Remazolam is an acting,safe,and effective sedative,which has little effect on hemodynamics and is suitable for most patients.TAPB combined with remazolam can reduce the dosage of total anesthetic drugs,reduce adverse reactions,reduce stress reactions,and facilitate the rapid postoperative recovery of patients.
基金This work presented in this paper was funded by the National Natural Science Foundation of China(Grant Nos.51478031 and 51278046)Shenzhen Science and Technology Innovation Fund(Grant No.FA24405041).The authors are grateful to the editor and reviewers for discerning comments on this paper.
文摘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.
基金supported by the General Program of the National Natural Science Foundation of China(Grant No.52074295)the Special Fund for Basic Scientific Research Business Expenses of Central Universities(Grant No.2022YJSSB06)supported by State Key Laboratory for Geomechanics and Deep Underground Engineering,China University of Mining and technology,Beijing,China(Grant No.SKLGDUEK202217).
文摘A nuclear explosion in the rock mass medium can produce strong shock waves,seismic shocks,and other destructive effects,which can cause extreme damage to the underground protection infrastructures.With the increase in nuclear explosion power,underground protection engineering enabled by explosion-proof impact theory and technology ushered in a new challenge.This paper proposes to simulate nuclear explosion tests with on-site chemical explosion tests in the form of multi-hole explosions.First,the mechanism of using multi-hole simultaneous blasting to simulate a nuclear explosion to generate approximate plane waves was analyzed.The plane pressure curve at the vault of the underground protective tunnel under the action of the multi-hole simultaneous blasting was then obtained using the impact test in the rock mass at the site.According to the peak pressure at the vault plane,it was divided into three regions:the stress superposition region,the superposition region after surface reflection,and the approximate plane stress wave zone.A numerical simulation approach was developed using PFC and FLAC to study the peak particle velocity in the surrounding rock of the underground protective cave under the action of multi-hole blasting.The time-history curves of pressure and peak pressure partition obtained by the on-site multi-hole simultaneous blasting test and numerical simulation were compared and analyzed,to verify the correctness and rationality of the formation of an approximate plane wave in the simulated nuclear explosion.This comparison and analysis also provided a theoretical foundation and some research ideas for the ensuing study on the impact of a nuclear explosion.
