Although the plastic loading can enhance creep deformation and yield strength,the anisotropic Stress Relaxation Aging(SRA)behavior and mechanism under plastic loading remain unclear,which presents a significant challe...Although the plastic loading can enhance creep deformation and yield strength,the anisotropic Stress Relaxation Aging(SRA)behavior and mechanism under plastic loading remain unclear,which presents a significant challenge in accurately shaping aluminum alloy panels.In this study,the SRA behavior of 2195-T4 Al-Cu-Li alloys were thoroughly studied under initial loading stresses within the elastic(210/250 MPa)and plastic(380/420 MPa)ranges at 180℃by stress relaxation and tensile tests as well as microstructure characterization.The findings reveal that compared with those under elastic loadings,in-plane anisotropy(IPA)values of the stress relaxation amount,yield strength and fracture elongation under plastic loadings are reduced by 60%–80%,70%–90% and 72%–89%,respectively.Similarly,IPA values of precipitate size in grains and PrecipitationFree Zones(PFZ)width at grain boundaries under plastic loading decrease by 31.4%and 94.4%respectively.These results indicate plastic loading significantly weakens the anisotropic SRA behavior,owing to numerous uniformly distributed fine T1phases and small IPA values of both T1precipitates size and PFZ width in various loading directions.Compared with those of elastic loadingaged alloys,yield strength of plastic loading-aged alloys shows high strength-ductility because of the combined effect of closely dispersed fine T1precipitates,narrowed PFZ and numerous sheared and rotated T1phases at different locations during tensile process.The uniformly distributed larger Kernel Average Misorientation(KAM)and Schmidt factor values of the plastic loading-aged alloy,as well as the cross-slip generated,also help to enhance the strength and ductility of the alloy.展开更多
Due to batteries inconsistencies and potential faults in battery management systems,slight overcharging remains a common yet insufficiently understood safety risk,lacking effective warning methods.To illuminate the de...Due to batteries inconsistencies and potential faults in battery management systems,slight overcharging remains a common yet insufficiently understood safety risk,lacking effective warning methods.To illuminate the degradation behavior and failure mechanism of various overcharged states(100%SOC,105%SOC,110%SOC,and 115%SOC),multiple advanced in-situ characterization techniques(accelerating rate calorimeter,electrochemical impedance spectroscopy,ultrasonic scanning,and expansion instrument)were utilized.Additionally,re-overcharge-induced thermal runaway(TR)tests were conducted,with a specific emphasis on the evolution of the expansion force signal.Results indicated significant degradation at 110%SOC including conductivity loss,loss of lithium inventory,and loss of active material accompanied by internal gas generation.These failure behaviors slow down the expansion force rate during reovercharging,reducing the efficacy of active warnings that depend on rate thresholds of expansion force.Specifically,the warning time for 115%SOC battery is only 144 s,which is 740 s shorter than that for fresh battery,and the time to TR is advanced by 9 min.Moreover,the initial self-heating temperature(T1)is reduced by 62.4℃compared to that of fresh battery,reaching only 70.8℃.To address the low safety of overcharged batteries,a passive overcharge warning method utilizing relaxation expansion force was proposed,based on the continued gas generation after stopping charging,leading to a sustained increase in force.Compared to active methods that rely on thresholds of expansion force rate,the passive method can issue warnings 115 s earlier.By combining the passive and active warning methods,guaranteed effective overcharge warning can be issued 863-884 s before TR.This study introduces a novel perspective for enhancing the safety of batteries.展开更多
BACKGROUND Most patients who were included in previous studies on achalasia had increased lower esophageal sphincter(LES)pressure.Peroral endoscopic myotomy(POEM)has been confirmed to be effective at relieving the cli...BACKGROUND Most patients who were included in previous studies on achalasia had increased lower esophageal sphincter(LES)pressure.Peroral endoscopic myotomy(POEM)has been confirmed to be effective at relieving the clinical symptoms of achalasia associated with increased LES pressure.AIM To identify the safety and efficacy of POEM for patients with normal LES integrated relaxation pressure(LES-IRP).METHODS The clinical data of patients who underwent POEM successfully in The First Medical Center of Chinese PLA General Hospital were retrospectively analyzed.A total of 481 patients who underwent preoperative high-resolution manometry(HRM)at our hospital were ultimately included in this research.According to the HRM results,the patients were divided into two groups:71 patients were included in the normal LES-IRP group(LES-IRP<15 mmHg)and 410 patients were included in the increased LES-IRP group(LES-IRP≥15 mmHg).Clinical characteristics,procedure-related parameters,adverse events,and outcomes were compared between the two groups to evaluate the safety and efficacy of POEM for patients with normal LES-IRP.RESULTS Among the 481 patients included in our study,209 were males and 272 were females,with a mean age of 44.2 years.All patients underwent POEM without severe adverse events.The median pre-treatment Eckardt scores of the normal LES-IRP and increased LES-IRP groups were 7.0 and 7.0(P=0.132),respectively,decreasing to 1.0 and 1.0 post-treatment(P=0.572).The clinical success rate of the normal LES-IRP group was 87.3%(62/71),and that of the increased LES-IRP group was 91.2%(374/410)(P=0.298).Reflux symptoms were measured by the GerdQ questionnaire,and the percentages of patients with GerdQ scores≥9 in the normal LES-IRP and increased LES-IRP groups were 8.5%and 10.7%,respectively(P=0.711).After matching,the rates of clinical success and the rates of GerdQ score≥9 were not significantly different between the two groups.CONCLUSION Our results suggest that POEM is safe and effective for achalasia and patients with normal LES-IRP.In addition,in patients with normal LES-IRP,compared with those with increased LES-IRP,POEM was not associated with a greater incidence of reflux symptoms.展开更多
In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order hom...In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.展开更多
Structural fine-tuning is of significant importance to enhance the magnetic anisotropy and elucidate the magneto-structural relationship for single molecule magnets(SMMs).For this purpose,two mononuclear Dy^(3+) SMMs:...Structural fine-tuning is of significant importance to enhance the magnetic anisotropy and elucidate the magneto-structural relationship for single molecule magnets(SMMs).For this purpose,two mononuclear Dy^(3+) SMMs:[Dy{HB(pz)3}2(Sal)](1) and [Dy{HB(pz)_(3)}_(2)(MeO-Sal)](2),where HB(pz)_(3)^(-)represents hydro tris(pyrazolyl)borate,Sal denotes salicyiaidehyde and MeO-Sal stands for 5-methoxysalicylaldehyde,were designed and synthesized.Single crystal X-ray diffraction tests show that the two SMMs have very similar eight-coordinated molecule structures,although the introducing of-MeO substituent on salicyiaidehyde ligand induces the changes on the molecule packing mode and the space group.Both the two SMMs have a Dy-O_(aryloxidebond) that is significantly shorter than other Dy-O/N bonds,which defines the orientation of main anisotropy axis of the ground Kramers doublets and engenders the slow relaxation of the magnetization behavior,as evidenced by the magnetic susceptibility and the ab initio calculation.Though with an electron-donating substituent on the axial Sal ligand in 2,the collective magnetic anisotropy is not enhanced and the corresponding magneto-structural relationship is discussed based on the experimental and theoretical calculation results.In addition,as neutral molecules,1 and 2 are soluble in several common organic solvents,like CH_(2)Cl_(2),CHCl_(3),THF and so on.展开更多
The effect of cryogenic treatment(CT)and relaxation annealing on the average nearest neighboring distance of atom(dm),ther-modynamic stability,soft magnetic properties,microhardness(Hv),and corrosion resistance of as-...The effect of cryogenic treatment(CT)and relaxation annealing on the average nearest neighboring distance of atom(dm),ther-modynamic stability,soft magnetic properties,microhardness(Hv),and corrosion resistance of as-spun(Fe_(0.5)Co_(0.5))_(75)B_(21)Nb_(4) metallic glasses(MGs)is studied.On the premise of maintaining a fully amorphous phase,appropriate CT and relaxation annealing are conducive to achieving the synergistic effect of increasing saturation magnetization(M_(s))and reducing coercivity(H_(c)).Shallow CT at 213 K optim-ally enhances the soft magnetic properties of MGs.Given its low activation energy of nucleation and increased activation energy of growth,appropriate CT is beneficial for achieving uniform annealed nanocrystals in amorphous phases.The correlation between free volumes(FVs)and potential energy suggests that the variation in Hc depends on the expansion and contraction behavior of amorphous phases after different CT processes.The fitting formulas of H_(c)–d_(m) and Ms–Hv correlations demonstrate that soft magnetic parameters have a solid linear relationship with the contents of FVs and degree of dense random packing.Moreover,pitting resistance is improved by ap-propriate CT and relaxation annealing.This improvement is characterized by the promotion of the stability of the Nb-rich passive film formed during electrochemical corrosion in 3.5wt%NaCl solution.展开更多
The reconfigurable intelligent surfaces(RIS)can reconfigure the wireless channel environment by manipulating the propagation of incident electromagnetic waves.Specifically,we consider using multi-RIS to improve the sy...The reconfigurable intelligent surfaces(RIS)can reconfigure the wireless channel environment by manipulating the propagation of incident electromagnetic waves.Specifically,we consider using multi-RIS to improve the system throughput of limited feedback multiple input single output(MISO)system in an energy efficiency manner.The critical challenge lies in the joint design of channel acquisition and beamforming which are usually based on codebook with limited precision.To solve this,we propose a semi-definite relaxation(SDR)based beamforming design scheme while considering the effect of cascaded channel acquisition.First,a channel quantization scheme is proposed by exploiting the channel sparsity in double-RIS aided MISO system.Second,an optimization problem of maximizing the system throughput is established to derive the channel quantization vector which also serves as the beamforming vector,with the consideration of the constraints of transmission power,RISs phase-shift.Third,a SDR based iterative optimization algorithm is proposed to solve the problem with low complexity.Finally,simulation results show that our proposed algorithm can improve the system throughput efficiently.展开更多
Two CoⅡ-based complexes,{[Co(dps)_(2)(N_(3))_(2)]·H_(2)O}_n(1)and[Co(dps)_(2)(N_(3))_(2)]_n(2),show a 1D chain and a 3D network,respectively.The central CoⅡions in the complexes have the same coordination envir...Two CoⅡ-based complexes,{[Co(dps)_(2)(N_(3))_(2)]·H_(2)O}_n(1)and[Co(dps)_(2)(N_(3))_(2)]_n(2),show a 1D chain and a 3D network,respectively.The central CoⅡions in the complexes have the same coordination environment with the[Co(dps)_(4)(N_(3))_(2)]unit.Although the differences in crystal parameters are nearly negligible,their magnetic properties are very different.AC susceptibility data show that 1 behaves as a typical field-induced single-ion magnet(SIM)with the out-of-phase(χ_(M)”)signals,while 2 shows ac signals ofχ_(M)”without peaks even under applied dc filed within our measurement window.Far-IR magneto-spectra(FIRMS)show strong spin-phonon couplings at 0 T in 2,likely making the magnetic relaxation in 2 fast,while the couplings are negligible in 1.Small spin-phonon coupling in 1 likely leads to slower magnetic relaxation,making 1 a SIM.The difference in the properties is due to the structural rigidity of 2 in its 3D network,leading to stronger spin-phonon coupling.Combined high-field EPR(HF-EPR)and FIRMS studies give spin-Hamiltonian parameters,including D=64.0(9)cm^(-1),|E|=15.7(2)cm^(-1)for 1 and D=80.0(2)cm^(-1),|E|=19.0(1)cm^(-1)for 2.展开更多
During cellular proliferation DNA undergoes frequent rep-lication cycles in which errors inevitably accumulate.DNA simultaneously faces continuous damage from endogenous sources[e.g.,reactive oxygen species(ROS)]and e...During cellular proliferation DNA undergoes frequent rep-lication cycles in which errors inevitably accumulate.DNA simultaneously faces continuous damage from endogenous sources[e.g.,reactive oxygen species(ROS)]and environmen-tal stressors,such as ultraviolet(UV)and ionizing radiation(IR).Such lesions compromise genomic stability and may escalate into DNA double-strand breaks(DSBs).Failure to repair DSBs can ultimately trigger cell death1.展开更多
The stretching-induced phase transition of biodegradable poly(butylene succinate)(PBS)was explored using a combination of mechanical testing and in situ wide angle X-ray diffraction characterization.The phase transiti...The stretching-induced phase transition of biodegradable poly(butylene succinate)(PBS)was explored using a combination of mechanical testing and in situ wide angle X-ray diffraction characterization.The phase transition fromαphase toβphase can be effectively triggered by severe stretching,in which the threshold strain is dependent on the PBS crystallites.Interestingly,thisα-βphase transition can be reversed immediately once mechanical stretching begins to be released.It should be pointed out that the finish ofβ-αphase transition reversed,corresponding to the disappearance of the generatedβphase,does not necessarily need the external stretching to completely release.For the relaxation-reversed phase transition,the evolution of the normalizedβ-phase fraction exhibited a similar correlation with the stress released.It was indicated that the decay kinetics followed a stretching-dominant mechanism,and the amount ofβphase generated just prior to relaxation had a negligible influence on the reversed phase transition.展开更多
The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs.Towards this end,a powerful technique is presented w...The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs.Towards this end,a powerful technique is presented which integrates 2D NMR T_(1)-T_(2) relaxation measurements with molecular dynamics(MD)simulations of hydrocarbons confined in the nanopores of kerogen.The integrated NMR-MD technique is demonstrated using T_(1)-T_(2) measurements of kerogen isolates and organic-rich chalks saturated with heptane,together with MD simulations of heptane completely dissolved in a realistic kerogen model.The NMR-MD results are used to extract the swelling ratio and nanopore size distribution of kerogen as a function of depth in the reservoir.The effects of organic nanoconfinement on the T_(1) relaxation dispersion and T_(2) residual dipolar coupling of heptane are investigated,as well as the effect of downhole effective stress on the kerogen nanopore size as a function of depth and compaction.Potential applications in partially depleted gas shale reservoirs are discussed,including CO_(2) utilization/geostorage,geostorage of green H2,and integration of the NMR-MD technique with thermodynamic models for predicting the competitive sorption of gas mixtures in kerogen.展开更多
Metal foils have emerged as one of the promising materials for anode-free batteries due to their high energy density and scalability in production.The unclear lithium plating/stripping kinetics of metal foil current c...Metal foils have emerged as one of the promising materials for anode-free batteries due to their high energy density and scalability in production.The unclear lithium plating/stripping kinetics of metal foil current collectors in anode-free batteries was addressed by using the non-destructive distribution of relaxation times(DRT)analysis to systematically investigate the lithium transport behavior of 14 metal foils and its correlation with electrochemical performance.By integrating energy-dispersive spectro scopy(EDS),cyclic voltammetry(CV),and galvanostatic testing,the exceptional properties of indium(In),tin(Sn),and silver(Ag)were revealed:the Li-In alloying reaction exhibits high reversibility,Li-Sn alloys demonstrate outstanding cycling stability,and the Li-Ag solid-solution mechanism provides an ideal lithium deposition interface on the silver substrate.The DRT separates the polarization internal resistance of lithium ions passing through the SEI layer(R_(sei),τ2)and the polarization internal resistance of lithium ions undergoing charge transfer reaction at the electrolyte/electrode interface(R_(ct),τ3)by decoupling the electrochemical impedance spectroscopy(EIS).For the first time,the correlation betweenτ2,τ3,and the cycle life/Coulombic efficiency of alloy/solid-solution metals was established,while non-alloy metals are not suitable for this method due to differences in lithium deposition mechanisms.This study not only illuminates the structure-property relationship governing the lithium kinetics of metal foil electrodes but also provides a novel non-destructive analytical strategy and theoretical guidance for the rational design of stable anodes in high-energy-density batteries,facilitating the efficient screening and optimization of anode-free battery.展开更多
InAs/AlAs superlattice structures have significant potential for application in low-noise avalanche photodetectors.With their performance in practical applications linked to the fundamental physical properties of carr...InAs/AlAs superlattice structures have significant potential for application in low-noise avalanche photodetectors.With their performance in practical applications linked to the fundamental physical properties of carrier relaxation time,this study investigated the carrier relaxation times of InAs/AlAs superlattices across various monolayers,temperatures,and carrier concentrations.Our investigation indicated that relaxation times span several tens of picoseconds,confirming that high-quality interfaces do not significantly reduce relaxation times in the way defect states might.Moreover,our study demonstrates that adjustments to the superlattice period can effectively modulate both the bandgap and carrier relaxation times,potentially impacting the performance of avalanche photodiodes by altering the electron-phonon interaction pathways and bandgap width.We established that lower temperatures contribute to an increase in the bandgap and the suppression of high-frequency optical phonon vibrations,thereby lengthening the relaxation times.Additionally,our observations indicate that in InAs/AlAs superlattices,the relaxation time increases as the excitation power increases,owing to the phonon bottleneck effect.These insights into InAs/AlAs superlattice carrier dynamics highlight their applicability in enhancing avalanche photodetectors,and may contribute to the optimized design of superlattices for specific applications.展开更多
Erratum to:International Journal of Minerals,Metallurgy and Materials Volume 31,Number 1,January 2024,Page 186 https://doi.org/10.1007/s12613-023-2744-0 The original version of this article unfortunately contained thr...Erratum to:International Journal of Minerals,Metallurgy and Materials Volume 31,Number 1,January 2024,Page 186 https://doi.org/10.1007/s12613-023-2744-0 The original version of this article unfortunately contained three mistakes.The presentation of Fig.8 in original version was incorrect.The correct version is given below.展开更多
This paper is devoted to the existence results for a class of neutral abstract fractional differential equations involving the composite relaxation process.Based on the Laplace transform,the semigroup theory and the W...This paper is devoted to the existence results for a class of neutral abstract fractional differential equations involving the composite relaxation process.Based on the Laplace transform,the semigroup theory and the Wright functions,we first introduce a definition of mild solutions to the considered problem.By means of the noncompactness of measure and the fixed point technique,we establish existence criteria of solutions.Finally,an example is presented to illustrate our main result.展开更多
Objective:To explore the application effect of MBSR combined with relaxation training in the perioperative period of radiofrequency ablation combined with ozone interventional therapy for lumbar disc herniation.Method...Objective:To explore the application effect of MBSR combined with relaxation training in the perioperative period of radiofrequency ablation combined with ozone interventional therapy for lumbar disc herniation.Methods:90 patients with lumbar disc herniation who underwent radiofrequency ablation(RFA)combined with ozone interventional therapy in the Orthopedics and Traumatology Department of our hospital from January to December 2019 were included as research samples.They were randomly divided into two groups using a random number table method:the control group(45 cases)received routine perioperative nursing and health education;the experimental group(45 cases)received a comprehensive psychological intervention program consisting of MBSR combined with relaxation training in addition to the control group’s treatment.Changes in pain perception(VAS),sleep quality(PSQI),psychological state(SAS/SDS),and life satisfaction(SWLS)were compared between the two groups before and after the intervention.Results:After the intervention,both groups showed a significant decrease in SAS and SDS scores(P<0.05),with a greater decrease in the experimental group(P<0.05);the experimental group had lower PSQI total scores and scores in each dimension compared to the control group(P<0.05);the experimental group had a significantly lower VAS score(3.56±0.88)compared to the control group(5.94±0.62)(P<0.05);the experimental group had a higher SWLS score(28.59±5.61)compared to the control group(22.46±4.15)(P<0.05).Conclusion:MBSR combined with relaxation training can significantly optimize the perioperative psychological state of patients undergoing RFA combined with ozone interventional therapy,reduce pain sensitivity and stress responses,and simultaneously improve sleep quality and treatment satisfaction.展开更多
The time-dependent viscoelastic response of cement-based materials to applied deformation is far from fully understood at the atomic level.Calcium silicate hydrate(C-S-H),the main hydration product of Portland cement,...The time-dependent viscoelastic response of cement-based materials to applied deformation is far from fully understood at the atomic level.Calcium silicate hydrate(C-S-H),the main hydration product of Portland cement,is responsible for the viscoelastic mechanism of cement-based materials.In this study,a molecular model of C-S-H was developed to explain the stress relaxation characteristics of C-S-H at different initial deformation states,Ca/Si ratios,temperatures,and water contents,which cannot be accessed experimentally.The stress relaxation of C-S-H occurs regardless of whether it is subjected to initial shear,tensile,or compressive deformation,and shows a heterogeneous characteristic.Water plays a crucial role in the stress relaxation process.A large Ca/Si ratio and high temperature reduce the cohesion between the calcium-silicate layer and the interlayer region,and the viscosity of the interlayer region,thereby accelerating the stress relaxation of C-S-H.The effect of the hydrogen bond network and the morphology of C-S-H on the evolution of the stress relaxation characteristics of C-S-H at different water contents was elucidated by nonaffine mean squared displacement.Our results shed light on the stress relaxation characteristics of C-S-H from a microscopic perspective,bridging the gap between the microscopic phenomena and the underlying atomic-level mechanisms.展开更多
Large 2219 Al-Cu alloy aerospace integral components suffer from long-term stress relaxation aging(SRA)due to complex temperature and stress loads during aging treatment/forming and service process,which makes it diff...Large 2219 Al-Cu alloy aerospace integral components suffer from long-term stress relaxation aging(SRA)due to complex temperature and stress loads during aging treatment/forming and service process,which makes it difficult to ensure their appropriate residual stress and excellent mechanical and service prop-erties.However,the research is limited to a thorough understanding of macroscopic and microscopic features and underlying mechanisms of the long-term SRA under multivariable aging conditions.There-fore,this study investigated macroscopic and microscopic features of long-term SRA under different tem-peratures(120 ℃ to 190 ℃),initial stress levels(100 MPa to 250 MPa)and durations(0 h to 50 h)through stress relaxation curves,metallographic traits,Vickers hardness,tensile performance,disloca-tions and phases of precipitation.On the basis of experimental outcomes,the comprehensive mecha-nisms beneath SRA were unraveled through dislocation theory,multiphase strengthening mechanisms and thermodynamics,where the interplays of stress relaxation behavior with age-hardening response were taken into consideration.The results showed elevations in the rate of stress reduction as the tem-perature and initial stress rose.At an initial stress greater than the yield stress of alloy,a marked in-crease in stress relaxation was found,and the mechanisms transform from the intragranular motion of dislocations and diffusion of grain boundaries to the intragranular and intergranular motion of disloca-tions and migration of grain boundaries.The stress reduction rate rose sharply when the temperature exceeded 175 ℃,and the dislocation movement mechanisms transform from gliding to climbing of dislo-cations.Stress relaxation is in nature progressive transformation of strain from elastic into a permanently inelastic state via the motion of dislocations,leading to the decrease of movable dislocations and the increase of immovable dislocations with more stable configurations.The age hardening is mainly deter-mined by precipitation strengthening,supplementarily by dislocation strengthening,and obvious stress orientation effect(SOE)of G.P.zones and θ"phases degenerates strengthening effect.The interplay be-tween stress relaxation behavior and age-hardening response influences the thermal-mechanical coupling SRA of 2219 Al-Cu alloy,which depends fundamentally on the motion of dislocations and their interplay with precipitated phases.This is a thermal activation process concerning the interplay between internal(age-hardening resistance)stress and external(initial)stress.The initial energy of elastic strain offers Gibbs free energy as the SRA driver,and a steady state of stress relaxation is attained with the lowest energy of elastic strain.These findings provide valuable insights into exploring innovative aging treat-ment/forming for optimizing residual stress,mechanical performance and service property in a synergistic manner.展开更多
Lanthanide complex-based materials with magnetic and luminescent properties have received a great deal of attention,owing to their importantly potential applications in diverse fields.In this work,the 9-anthracenecarb...Lanthanide complex-based materials with magnetic and luminescent properties have received a great deal of attention,owing to their importantly potential applications in diverse fields.In this work,the 9-anthracenecarboxylic acid(9-Haca)as bridging ligand was applied in combination with optically activeπ-conjugated 2,4,6-tri(2-pyridyl)-1,3,5-triazine(tptz)to construct a series of new di-nuclear and tetranuclear lanthanide 9-anthracenecarboxylates[La_(2)(9-aca)_(6)(tptz)_(2)(μ-H_(2)O)]·0.25H_(2)O(1),[Ln_(2)(9-aca)_(6)(tptz)_(2)(H_(2)O)_(2)]·0.5AQ·CH_(3)COOH_(2)H_(2)O[Ln=Sm(2a),Eu(2b),Gd(2c),Tb(2d),Dy(2e),Tm(2f);AQ=9,10-anthracenedione]and[Ln_(4)(9-aca)_(10)(tptz)_(2)(CH3COO)2]·H_(2)O[Ln=Eu(3a),Gd(3b),Dy(3c)].1 displays a di-nuclear centrosymmetric moiety[La_(2)(9-aca)_(6)(tptz)_(2)(μ-H_(2)O)]built up from two complex[La(9-aca)_(2)(tptz)]groups bridged by one H_(2)O molecule and two syn-syn-μ2-η1:η1-9-aca-bridging ligands,while 2a-2f are isostructural and co mprise another di-nuclear centrosymmetric moieties[Ln_(2)(9-aca)_(6)(tptz)_(2)(H_(2)O)_(2)]based on two complex[Ln(9-aca)_(2)(tptz)(H_(2)O)]groups connected by two syn-syn-μ2-η1:η1-9-aca-bridging ligands,3a-3c are isostructural and show tetra-nuclear centro symmetric moieties[Ln4(9-aca)10(tptz)2(CH3COO)2]containing three types of coordination modes of 9-aca-ligands.The present compounds offer the only examples of lanthanide 9-anthracenecarboxylates decorated by optically active tptz.Magnetic investigations of 2a,2c-2f,and 3b-3c indicate that 3c is typical of slow relaxation of the magnetization,while 2c and 3b show significant magnetocaloric effect(MCE)with the value of-ΔSm of 5.26 J/(kg·K)at 4 K and 15.65 J/(kg·K)at 2 K(ΔH=7 T),respectively.The luminescent properties were also studied and reveal that the characteristic luminescent properties of the 7r-conjugated aromatic ligands are introduced into magnetic lanthanide 9-anthracenecarboxylates,simultaneously exhibiting slow magnetic relaxation(or MCE)and luminescent properties.展开更多
The occurrence of geological hazards and the instability of geotechnical engineering structures are closely related to the time-dependent behavior of rock.However,the idealization boundary condition for constant stres...The occurrence of geological hazards and the instability of geotechnical engineering structures are closely related to the time-dependent behavior of rock.However,the idealization boundary condition for constant stress in creep or constant strain in relaxation is not usually attained in natural geological systems.Therefore,generalized relaxation tests that explore the simultaneous changes of stress and strain with time under different stress levels with constant pore-water pressure are conducted in this study.The results show that in area Ⅰ,area Ⅱ,and area Ⅲ,the stress and strain both change synchronously with time and show similar evolutionary laws as the strain-time curve for creep or the stress-time curve for relaxation.When the applied stress level surpasses the δ_(ci) or δ_(cd) threshold,the variations in stress and strain and their respective rates of change exhibit a significant increase.The radial deformation and its rate of change exhibit greater sensitivity in response to stress levels.The apparent strain deforms homogeneously at the primary stage,and subsequently,gradually localizes due to the microcrack development at the secondary stage.Ultimately,interconnection of the microcracks causes the formation of a shear-localization zone at the tertiary stage.The strain-time responses inside and outside the localization zone are characterized by local strain accumulation and inelastic unloading during the secondary and tertiary stages,respectively.The width of the shear-localization zone is found to range from 4.43 mm to 7.08 mm and increased with a longer time-to-failure.Scanning electron microscopy(SEM)reveals a dominant coalescence of intergranular cracks on the fracture surface,and the degree of physiochemical deterioration caused by water-rock interaction is more severe under a longer lifetime.The brittle sandstone’s time-dependent deformation is essentially controlled by microcrack development during generalized relaxation,and its expectancy-life is determined by its initial microstructural state and the rheological path.展开更多
基金support from the Key Program of the National Natural Science Foundation of China(No.51235010)。
文摘Although the plastic loading can enhance creep deformation and yield strength,the anisotropic Stress Relaxation Aging(SRA)behavior and mechanism under plastic loading remain unclear,which presents a significant challenge in accurately shaping aluminum alloy panels.In this study,the SRA behavior of 2195-T4 Al-Cu-Li alloys were thoroughly studied under initial loading stresses within the elastic(210/250 MPa)and plastic(380/420 MPa)ranges at 180℃by stress relaxation and tensile tests as well as microstructure characterization.The findings reveal that compared with those under elastic loadings,in-plane anisotropy(IPA)values of the stress relaxation amount,yield strength and fracture elongation under plastic loadings are reduced by 60%–80%,70%–90% and 72%–89%,respectively.Similarly,IPA values of precipitate size in grains and PrecipitationFree Zones(PFZ)width at grain boundaries under plastic loading decrease by 31.4%and 94.4%respectively.These results indicate plastic loading significantly weakens the anisotropic SRA behavior,owing to numerous uniformly distributed fine T1phases and small IPA values of both T1precipitates size and PFZ width in various loading directions.Compared with those of elastic loadingaged alloys,yield strength of plastic loading-aged alloys shows high strength-ductility because of the combined effect of closely dispersed fine T1precipitates,narrowed PFZ and numerous sheared and rotated T1phases at different locations during tensile process.The uniformly distributed larger Kernel Average Misorientation(KAM)and Schmidt factor values of the plastic loading-aged alloy,as well as the cross-slip generated,also help to enhance the strength and ductility of the alloy.
基金supported by the National Natural Science Foundation of China(52476200,52106244)the Guangdong Basic and Applied Basic Research Foundation(2024A1515030124)+1 种基金the Science and Technology Project of China Southern Power Grid under Grant GDKJXM20230246(030100KC23020017)the Fundamental Research Funds for the Central Universities。
文摘Due to batteries inconsistencies and potential faults in battery management systems,slight overcharging remains a common yet insufficiently understood safety risk,lacking effective warning methods.To illuminate the degradation behavior and failure mechanism of various overcharged states(100%SOC,105%SOC,110%SOC,and 115%SOC),multiple advanced in-situ characterization techniques(accelerating rate calorimeter,electrochemical impedance spectroscopy,ultrasonic scanning,and expansion instrument)were utilized.Additionally,re-overcharge-induced thermal runaway(TR)tests were conducted,with a specific emphasis on the evolution of the expansion force signal.Results indicated significant degradation at 110%SOC including conductivity loss,loss of lithium inventory,and loss of active material accompanied by internal gas generation.These failure behaviors slow down the expansion force rate during reovercharging,reducing the efficacy of active warnings that depend on rate thresholds of expansion force.Specifically,the warning time for 115%SOC battery is only 144 s,which is 740 s shorter than that for fresh battery,and the time to TR is advanced by 9 min.Moreover,the initial self-heating temperature(T1)is reduced by 62.4℃compared to that of fresh battery,reaching only 70.8℃.To address the low safety of overcharged batteries,a passive overcharge warning method utilizing relaxation expansion force was proposed,based on the continued gas generation after stopping charging,leading to a sustained increase in force.Compared to active methods that rely on thresholds of expansion force rate,the passive method can issue warnings 115 s earlier.By combining the passive and active warning methods,guaranteed effective overcharge warning can be issued 863-884 s before TR.This study introduces a novel perspective for enhancing the safety of batteries.
文摘BACKGROUND Most patients who were included in previous studies on achalasia had increased lower esophageal sphincter(LES)pressure.Peroral endoscopic myotomy(POEM)has been confirmed to be effective at relieving the clinical symptoms of achalasia associated with increased LES pressure.AIM To identify the safety and efficacy of POEM for patients with normal LES integrated relaxation pressure(LES-IRP).METHODS The clinical data of patients who underwent POEM successfully in The First Medical Center of Chinese PLA General Hospital were retrospectively analyzed.A total of 481 patients who underwent preoperative high-resolution manometry(HRM)at our hospital were ultimately included in this research.According to the HRM results,the patients were divided into two groups:71 patients were included in the normal LES-IRP group(LES-IRP<15 mmHg)and 410 patients were included in the increased LES-IRP group(LES-IRP≥15 mmHg).Clinical characteristics,procedure-related parameters,adverse events,and outcomes were compared between the two groups to evaluate the safety and efficacy of POEM for patients with normal LES-IRP.RESULTS Among the 481 patients included in our study,209 were males and 272 were females,with a mean age of 44.2 years.All patients underwent POEM without severe adverse events.The median pre-treatment Eckardt scores of the normal LES-IRP and increased LES-IRP groups were 7.0 and 7.0(P=0.132),respectively,decreasing to 1.0 and 1.0 post-treatment(P=0.572).The clinical success rate of the normal LES-IRP group was 87.3%(62/71),and that of the increased LES-IRP group was 91.2%(374/410)(P=0.298).Reflux symptoms were measured by the GerdQ questionnaire,and the percentages of patients with GerdQ scores≥9 in the normal LES-IRP and increased LES-IRP groups were 8.5%and 10.7%,respectively(P=0.711).After matching,the rates of clinical success and the rates of GerdQ score≥9 were not significantly different between the two groups.CONCLUSION Our results suggest that POEM is safe and effective for achalasia and patients with normal LES-IRP.In addition,in patients with normal LES-IRP,compared with those with increased LES-IRP,POEM was not associated with a greater incidence of reflux symptoms.
基金support by the National Key R&D Program of China(Grant No.2023YFA1008901)the National Natural Science Foundation of China(Grant Nos.11988102,12172009)is gratefully acknowledged.
文摘In this manuscript,we propose an analytical equivalent linear viscoelastic constitutive model for fiber-reinforced composites,bypassing general computational homogenization.The method is based on the reduced-order homogenization(ROH)approach.The ROH method typically involves solving multiple finite element problems under periodic conditions to evaluate elastic strain and eigenstrain influence functions in an‘off-line’stage,which offers substantial cost savings compared to direct computational homogenization methods.Due to the unique structure of the fibrous unit cell,“off-line”stage calculation can be eliminated by influence functions obtained analytically.Introducing the standard solid model to the ROH method enables the creation of a comprehensive analytical homogeneous viscoelastic constitutive model.This method treats fibrous composite materials as homogeneous,anisotropic viscoelastic materials,significantly reducing computational time due to its analytical nature.This approach also enables precise determination of a homogenized anisotropic relaxation modulus and accurate capture of various viscoelastic responses under different loading conditions.Three sets of numerical examples,including unit cell tests,three-point beam bending tests,and torsion tests,are given to demonstrate the predictive performance of the homogenized viscoelastic model.Furthermore,the model is validated against experimental measurements,confirming its accuracy and reliability.
基金Project supported by the Nature Science Foundation of Shaanxi Province (2023-JC-YB-137)National Natural Science Foundation of China (21901200)。
文摘Structural fine-tuning is of significant importance to enhance the magnetic anisotropy and elucidate the magneto-structural relationship for single molecule magnets(SMMs).For this purpose,two mononuclear Dy^(3+) SMMs:[Dy{HB(pz)3}2(Sal)](1) and [Dy{HB(pz)_(3)}_(2)(MeO-Sal)](2),where HB(pz)_(3)^(-)represents hydro tris(pyrazolyl)borate,Sal denotes salicyiaidehyde and MeO-Sal stands for 5-methoxysalicylaldehyde,were designed and synthesized.Single crystal X-ray diffraction tests show that the two SMMs have very similar eight-coordinated molecule structures,although the introducing of-MeO substituent on salicyiaidehyde ligand induces the changes on the molecule packing mode and the space group.Both the two SMMs have a Dy-O_(aryloxidebond) that is significantly shorter than other Dy-O/N bonds,which defines the orientation of main anisotropy axis of the ground Kramers doublets and engenders the slow relaxation of the magnetization behavior,as evidenced by the magnetic susceptibility and the ab initio calculation.Though with an electron-donating substituent on the axial Sal ligand in 2,the collective magnetic anisotropy is not enhanced and the corresponding magneto-structural relationship is discussed based on the experimental and theoretical calculation results.In addition,as neutral molecules,1 and 2 are soluble in several common organic solvents,like CH_(2)Cl_(2),CHCl_(3),THF and so on.
基金support from the National Natural Science Foundation of China(No.52271146)New 20 Items of Colleges and Universities in Jinan,China(No.202228111)University of Jinan Disciplinary Cross-Convergence Construction Project 2023,China(No.XKJC-202311).
文摘The effect of cryogenic treatment(CT)and relaxation annealing on the average nearest neighboring distance of atom(dm),ther-modynamic stability,soft magnetic properties,microhardness(Hv),and corrosion resistance of as-spun(Fe_(0.5)Co_(0.5))_(75)B_(21)Nb_(4) metallic glasses(MGs)is studied.On the premise of maintaining a fully amorphous phase,appropriate CT and relaxation annealing are conducive to achieving the synergistic effect of increasing saturation magnetization(M_(s))and reducing coercivity(H_(c)).Shallow CT at 213 K optim-ally enhances the soft magnetic properties of MGs.Given its low activation energy of nucleation and increased activation energy of growth,appropriate CT is beneficial for achieving uniform annealed nanocrystals in amorphous phases.The correlation between free volumes(FVs)and potential energy suggests that the variation in Hc depends on the expansion and contraction behavior of amorphous phases after different CT processes.The fitting formulas of H_(c)–d_(m) and Ms–Hv correlations demonstrate that soft magnetic parameters have a solid linear relationship with the contents of FVs and degree of dense random packing.Moreover,pitting resistance is improved by ap-propriate CT and relaxation annealing.This improvement is characterized by the promotion of the stability of the Nb-rich passive film formed during electrochemical corrosion in 3.5wt%NaCl solution.
基金supported the Innovation Talents Promotion Program of Shaanxi Province under Grant No.2021TD-08。
文摘The reconfigurable intelligent surfaces(RIS)can reconfigure the wireless channel environment by manipulating the propagation of incident electromagnetic waves.Specifically,we consider using multi-RIS to improve the system throughput of limited feedback multiple input single output(MISO)system in an energy efficiency manner.The critical challenge lies in the joint design of channel acquisition and beamforming which are usually based on codebook with limited precision.To solve this,we propose a semi-definite relaxation(SDR)based beamforming design scheme while considering the effect of cascaded channel acquisition.First,a channel quantization scheme is proposed by exploiting the channel sparsity in double-RIS aided MISO system.Second,an optimization problem of maximizing the system throughput is established to derive the channel quantization vector which also serves as the beamforming vector,with the consideration of the constraints of transmission power,RISs phase-shift.Third,a SDR based iterative optimization algorithm is proposed to solve the problem with low complexity.Finally,simulation results show that our proposed algorithm can improve the system throughput efficiently.
基金supported by the National Key Research and Development Program of China(No.2021YFA1600304)Joint Fund for Regional Innovation and Development(No.U20A2073)+4 种基金National Natural Science Foundation of China(Nos.22373048,21973038,61904119 and 22105089)Jiangxi Provincial Key Laboratory of Functional Molecular Materials Chemistry(No.20212BCD42018)US National Science Foundation(NSF,No.CHE-2055499)the Interdisciplinary program of Wuhan National High Magnetic Field Center(No.WHMFC202133)the support of the NSF Research Traineeship Program(No.DGE-2152168)。
文摘Two CoⅡ-based complexes,{[Co(dps)_(2)(N_(3))_(2)]·H_(2)O}_n(1)and[Co(dps)_(2)(N_(3))_(2)]_n(2),show a 1D chain and a 3D network,respectively.The central CoⅡions in the complexes have the same coordination environment with the[Co(dps)_(4)(N_(3))_(2)]unit.Although the differences in crystal parameters are nearly negligible,their magnetic properties are very different.AC susceptibility data show that 1 behaves as a typical field-induced single-ion magnet(SIM)with the out-of-phase(χ_(M)”)signals,while 2 shows ac signals ofχ_(M)”without peaks even under applied dc filed within our measurement window.Far-IR magneto-spectra(FIRMS)show strong spin-phonon couplings at 0 T in 2,likely making the magnetic relaxation in 2 fast,while the couplings are negligible in 1.Small spin-phonon coupling in 1 likely leads to slower magnetic relaxation,making 1 a SIM.The difference in the properties is due to the structural rigidity of 2 in its 3D network,leading to stronger spin-phonon coupling.Combined high-field EPR(HF-EPR)and FIRMS studies give spin-Hamiltonian parameters,including D=64.0(9)cm^(-1),|E|=15.7(2)cm^(-1)for 1 and D=80.0(2)cm^(-1),|E|=19.0(1)cm^(-1)for 2.
基金supported by grants fromthe Shenzhen Medical Research Fund(Grant No.A2302040).
文摘During cellular proliferation DNA undergoes frequent rep-lication cycles in which errors inevitably accumulate.DNA simultaneously faces continuous damage from endogenous sources[e.g.,reactive oxygen species(ROS)]and environmen-tal stressors,such as ultraviolet(UV)and ionizing radiation(IR).Such lesions compromise genomic stability and may escalate into DNA double-strand breaks(DSBs).Failure to repair DSBs can ultimately trigger cell death1.
基金supported by the National Natural Science Foundation of China(No.52273025).
文摘The stretching-induced phase transition of biodegradable poly(butylene succinate)(PBS)was explored using a combination of mechanical testing and in situ wide angle X-ray diffraction characterization.The phase transition fromαphase toβphase can be effectively triggered by severe stretching,in which the threshold strain is dependent on the PBS crystallites.Interestingly,thisα-βphase transition can be reversed immediately once mechanical stretching begins to be released.It should be pointed out that the finish ofβ-αphase transition reversed,corresponding to the disappearance of the generatedβphase,does not necessarily need the external stretching to completely release.For the relaxation-reversed phase transition,the evolution of the normalizedβ-phase fraction exhibited a similar correlation with the stress released.It was indicated that the decay kinetics followed a stretching-dominant mechanism,and the amount ofβphase generated just prior to relaxation had a negligible influence on the reversed phase transition.
基金Vinegar Technologies LLC,Chevron Energy Technology Company,Rice University Consortium for Processes in Porous Media,and the American Chemical Society Petroleum Research Fund(No.ACS PRF 58859-ND6)for their financial support。
文摘The characterization of kerogen nanopores is crucial for predicting the geostorage capacity and recoverability of natural gas in unconventional gas shale reservoirs.Towards this end,a powerful technique is presented which integrates 2D NMR T_(1)-T_(2) relaxation measurements with molecular dynamics(MD)simulations of hydrocarbons confined in the nanopores of kerogen.The integrated NMR-MD technique is demonstrated using T_(1)-T_(2) measurements of kerogen isolates and organic-rich chalks saturated with heptane,together with MD simulations of heptane completely dissolved in a realistic kerogen model.The NMR-MD results are used to extract the swelling ratio and nanopore size distribution of kerogen as a function of depth in the reservoir.The effects of organic nanoconfinement on the T_(1) relaxation dispersion and T_(2) residual dipolar coupling of heptane are investigated,as well as the effect of downhole effective stress on the kerogen nanopore size as a function of depth and compaction.Potential applications in partially depleted gas shale reservoirs are discussed,including CO_(2) utilization/geostorage,geostorage of green H2,and integration of the NMR-MD technique with thermodynamic models for predicting the competitive sorption of gas mixtures in kerogen.
基金supported by the Quzhou Science and Technology Bureau Project(2023D023,2023D030,2023D002,and2024D028)the Joint Funds of the Zhejiang Provincial Natural Science Foundation of China(LZY23B030002)+3 种基金the Shijiazhuang Shangtai Technology Co.,Ltd.Hebei Provincial Department of Science and Technology(24291101Z)the International Cooperation Projects of Sichuan Provincial Department of Science and Technology(2021YFH0126)the Sichuan Provincial Science and Technology Department's key research project(2023YFG0203)。
文摘Metal foils have emerged as one of the promising materials for anode-free batteries due to their high energy density and scalability in production.The unclear lithium plating/stripping kinetics of metal foil current collectors in anode-free batteries was addressed by using the non-destructive distribution of relaxation times(DRT)analysis to systematically investigate the lithium transport behavior of 14 metal foils and its correlation with electrochemical performance.By integrating energy-dispersive spectro scopy(EDS),cyclic voltammetry(CV),and galvanostatic testing,the exceptional properties of indium(In),tin(Sn),and silver(Ag)were revealed:the Li-In alloying reaction exhibits high reversibility,Li-Sn alloys demonstrate outstanding cycling stability,and the Li-Ag solid-solution mechanism provides an ideal lithium deposition interface on the silver substrate.The DRT separates the polarization internal resistance of lithium ions passing through the SEI layer(R_(sei),τ2)and the polarization internal resistance of lithium ions undergoing charge transfer reaction at the electrolyte/electrode interface(R_(ct),τ3)by decoupling the electrochemical impedance spectroscopy(EIS).For the first time,the correlation betweenτ2,τ3,and the cycle life/Coulombic efficiency of alloy/solid-solution metals was established,while non-alloy metals are not suitable for this method due to differences in lithium deposition mechanisms.This study not only illuminates the structure-property relationship governing the lithium kinetics of metal foil electrodes but also provides a novel non-destructive analytical strategy and theoretical guidance for the rational design of stable anodes in high-energy-density batteries,facilitating the efficient screening and optimization of anode-free battery.
基金supported by the Science and Technology Innovation Program of Hunan Province(Grant No.2021RC4026)。
文摘InAs/AlAs superlattice structures have significant potential for application in low-noise avalanche photodetectors.With their performance in practical applications linked to the fundamental physical properties of carrier relaxation time,this study investigated the carrier relaxation times of InAs/AlAs superlattices across various monolayers,temperatures,and carrier concentrations.Our investigation indicated that relaxation times span several tens of picoseconds,confirming that high-quality interfaces do not significantly reduce relaxation times in the way defect states might.Moreover,our study demonstrates that adjustments to the superlattice period can effectively modulate both the bandgap and carrier relaxation times,potentially impacting the performance of avalanche photodiodes by altering the electron-phonon interaction pathways and bandgap width.We established that lower temperatures contribute to an increase in the bandgap and the suppression of high-frequency optical phonon vibrations,thereby lengthening the relaxation times.Additionally,our observations indicate that in InAs/AlAs superlattices,the relaxation time increases as the excitation power increases,owing to the phonon bottleneck effect.These insights into InAs/AlAs superlattice carrier dynamics highlight their applicability in enhancing avalanche photodetectors,and may contribute to the optimized design of superlattices for specific applications.
文摘Erratum to:International Journal of Minerals,Metallurgy and Materials Volume 31,Number 1,January 2024,Page 186 https://doi.org/10.1007/s12613-023-2744-0 The original version of this article unfortunately contained three mistakes.The presentation of Fig.8 in original version was incorrect.The correct version is given below.
基金Supported by the Guangxi Science and Technology base and Talent Project(AD23026249,AD22080047).
文摘This paper is devoted to the existence results for a class of neutral abstract fractional differential equations involving the composite relaxation process.Based on the Laplace transform,the semigroup theory and the Wright functions,we first introduce a definition of mild solutions to the considered problem.By means of the noncompactness of measure and the fixed point technique,we establish existence criteria of solutions.Finally,an example is presented to illustrate our main result.
基金General Project,Scientific Research Project Plan for Traditional Chinese Medicine in Hebei Province(Project No.:T2025117)。
文摘Objective:To explore the application effect of MBSR combined with relaxation training in the perioperative period of radiofrequency ablation combined with ozone interventional therapy for lumbar disc herniation.Methods:90 patients with lumbar disc herniation who underwent radiofrequency ablation(RFA)combined with ozone interventional therapy in the Orthopedics and Traumatology Department of our hospital from January to December 2019 were included as research samples.They were randomly divided into two groups using a random number table method:the control group(45 cases)received routine perioperative nursing and health education;the experimental group(45 cases)received a comprehensive psychological intervention program consisting of MBSR combined with relaxation training in addition to the control group’s treatment.Changes in pain perception(VAS),sleep quality(PSQI),psychological state(SAS/SDS),and life satisfaction(SWLS)were compared between the two groups before and after the intervention.Results:After the intervention,both groups showed a significant decrease in SAS and SDS scores(P<0.05),with a greater decrease in the experimental group(P<0.05);the experimental group had lower PSQI total scores and scores in each dimension compared to the control group(P<0.05);the experimental group had a significantly lower VAS score(3.56±0.88)compared to the control group(5.94±0.62)(P<0.05);the experimental group had a higher SWLS score(28.59±5.61)compared to the control group(22.46±4.15)(P<0.05).Conclusion:MBSR combined with relaxation training can significantly optimize the perioperative psychological state of patients undergoing RFA combined with ozone interventional therapy,reduce pain sensitivity and stress responses,and simultaneously improve sleep quality and treatment satisfaction.
基金This work is supported by the National Natural Science Foundation of China(Nos.51602229 and U2040222)the Opening Project of Key Laboratory of Advanced Civil Engineering Materials of Ministry of Education(Tongji University)the Water Conservancy Science and Technology Project of Hunan Province(No.XSKJ2021000-15),China.
文摘The time-dependent viscoelastic response of cement-based materials to applied deformation is far from fully understood at the atomic level.Calcium silicate hydrate(C-S-H),the main hydration product of Portland cement,is responsible for the viscoelastic mechanism of cement-based materials.In this study,a molecular model of C-S-H was developed to explain the stress relaxation characteristics of C-S-H at different initial deformation states,Ca/Si ratios,temperatures,and water contents,which cannot be accessed experimentally.The stress relaxation of C-S-H occurs regardless of whether it is subjected to initial shear,tensile,or compressive deformation,and shows a heterogeneous characteristic.Water plays a crucial role in the stress relaxation process.A large Ca/Si ratio and high temperature reduce the cohesion between the calcium-silicate layer and the interlayer region,and the viscosity of the interlayer region,thereby accelerating the stress relaxation of C-S-H.The effect of the hydrogen bond network and the morphology of C-S-H on the evolution of the stress relaxation characteristics of C-S-H at different water contents was elucidated by nonaffine mean squared displacement.Our results shed light on the stress relaxation characteristics of C-S-H from a microscopic perspective,bridging the gap between the microscopic phenomena and the underlying atomic-level mechanisms.
基金National Natural Science Foundation of China(No.52005018)Beijing Natural Science Foundation(No.3232022)+1 种基金Fundamental Research Funds for the Central Universities(No.FRF-TP-22-035A1)National Defense Basic Scientific Research Program of China(No.JCKY2020601C004).
文摘Large 2219 Al-Cu alloy aerospace integral components suffer from long-term stress relaxation aging(SRA)due to complex temperature and stress loads during aging treatment/forming and service process,which makes it difficult to ensure their appropriate residual stress and excellent mechanical and service prop-erties.However,the research is limited to a thorough understanding of macroscopic and microscopic features and underlying mechanisms of the long-term SRA under multivariable aging conditions.There-fore,this study investigated macroscopic and microscopic features of long-term SRA under different tem-peratures(120 ℃ to 190 ℃),initial stress levels(100 MPa to 250 MPa)and durations(0 h to 50 h)through stress relaxation curves,metallographic traits,Vickers hardness,tensile performance,disloca-tions and phases of precipitation.On the basis of experimental outcomes,the comprehensive mecha-nisms beneath SRA were unraveled through dislocation theory,multiphase strengthening mechanisms and thermodynamics,where the interplays of stress relaxation behavior with age-hardening response were taken into consideration.The results showed elevations in the rate of stress reduction as the tem-perature and initial stress rose.At an initial stress greater than the yield stress of alloy,a marked in-crease in stress relaxation was found,and the mechanisms transform from the intragranular motion of dislocations and diffusion of grain boundaries to the intragranular and intergranular motion of disloca-tions and migration of grain boundaries.The stress reduction rate rose sharply when the temperature exceeded 175 ℃,and the dislocation movement mechanisms transform from gliding to climbing of dislo-cations.Stress relaxation is in nature progressive transformation of strain from elastic into a permanently inelastic state via the motion of dislocations,leading to the decrease of movable dislocations and the increase of immovable dislocations with more stable configurations.The age hardening is mainly deter-mined by precipitation strengthening,supplementarily by dislocation strengthening,and obvious stress orientation effect(SOE)of G.P.zones and θ"phases degenerates strengthening effect.The interplay be-tween stress relaxation behavior and age-hardening response influences the thermal-mechanical coupling SRA of 2219 Al-Cu alloy,which depends fundamentally on the motion of dislocations and their interplay with precipitated phases.This is a thermal activation process concerning the interplay between internal(age-hardening resistance)stress and external(initial)stress.The initial energy of elastic strain offers Gibbs free energy as the SRA driver,and a steady state of stress relaxation is attained with the lowest energy of elastic strain.These findings provide valuable insights into exploring innovative aging treat-ment/forming for optimizing residual stress,mechanical performance and service property in a synergistic manner.
基金Project supported by the National Natural Science Foundation of China(21671029)Innovation andEntrepreneurship Team of Inorganic Optoelectronic Functional Materials for Chongqing Yingcai(cstc2021ycjh-bgzxm0131)+3 种基金MajorProject of the Science and Technology Research Program of Chongqing Education Commission of China(KJZD-M202100501)theInnovation Program for Chongqing’s Overseas Returnees(cx2019037)Natural Science Foundation of Chongqing,China(cstc2021jcyj-msxmX0380)Chongqing Normal University(21XLB034)。
文摘Lanthanide complex-based materials with magnetic and luminescent properties have received a great deal of attention,owing to their importantly potential applications in diverse fields.In this work,the 9-anthracenecarboxylic acid(9-Haca)as bridging ligand was applied in combination with optically activeπ-conjugated 2,4,6-tri(2-pyridyl)-1,3,5-triazine(tptz)to construct a series of new di-nuclear and tetranuclear lanthanide 9-anthracenecarboxylates[La_(2)(9-aca)_(6)(tptz)_(2)(μ-H_(2)O)]·0.25H_(2)O(1),[Ln_(2)(9-aca)_(6)(tptz)_(2)(H_(2)O)_(2)]·0.5AQ·CH_(3)COOH_(2)H_(2)O[Ln=Sm(2a),Eu(2b),Gd(2c),Tb(2d),Dy(2e),Tm(2f);AQ=9,10-anthracenedione]and[Ln_(4)(9-aca)_(10)(tptz)_(2)(CH3COO)2]·H_(2)O[Ln=Eu(3a),Gd(3b),Dy(3c)].1 displays a di-nuclear centrosymmetric moiety[La_(2)(9-aca)_(6)(tptz)_(2)(μ-H_(2)O)]built up from two complex[La(9-aca)_(2)(tptz)]groups bridged by one H_(2)O molecule and two syn-syn-μ2-η1:η1-9-aca-bridging ligands,while 2a-2f are isostructural and co mprise another di-nuclear centrosymmetric moieties[Ln_(2)(9-aca)_(6)(tptz)_(2)(H_(2)O)_(2)]based on two complex[Ln(9-aca)_(2)(tptz)(H_(2)O)]groups connected by two syn-syn-μ2-η1:η1-9-aca-bridging ligands,3a-3c are isostructural and show tetra-nuclear centro symmetric moieties[Ln4(9-aca)10(tptz)2(CH3COO)2]containing three types of coordination modes of 9-aca-ligands.The present compounds offer the only examples of lanthanide 9-anthracenecarboxylates decorated by optically active tptz.Magnetic investigations of 2a,2c-2f,and 3b-3c indicate that 3c is typical of slow relaxation of the magnetization,while 2c and 3b show significant magnetocaloric effect(MCE)with the value of-ΔSm of 5.26 J/(kg·K)at 4 K and 15.65 J/(kg·K)at 2 K(ΔH=7 T),respectively.The luminescent properties were also studied and reveal that the characteristic luminescent properties of the 7r-conjugated aromatic ligands are introduced into magnetic lanthanide 9-anthracenecarboxylates,simultaneously exhibiting slow magnetic relaxation(or MCE)and luminescent properties.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52304099,52172625)Shenzhen Science and Technology Program(Grant No.RCYX20221008092903013).
文摘The occurrence of geological hazards and the instability of geotechnical engineering structures are closely related to the time-dependent behavior of rock.However,the idealization boundary condition for constant stress in creep or constant strain in relaxation is not usually attained in natural geological systems.Therefore,generalized relaxation tests that explore the simultaneous changes of stress and strain with time under different stress levels with constant pore-water pressure are conducted in this study.The results show that in area Ⅰ,area Ⅱ,and area Ⅲ,the stress and strain both change synchronously with time and show similar evolutionary laws as the strain-time curve for creep or the stress-time curve for relaxation.When the applied stress level surpasses the δ_(ci) or δ_(cd) threshold,the variations in stress and strain and their respective rates of change exhibit a significant increase.The radial deformation and its rate of change exhibit greater sensitivity in response to stress levels.The apparent strain deforms homogeneously at the primary stage,and subsequently,gradually localizes due to the microcrack development at the secondary stage.Ultimately,interconnection of the microcracks causes the formation of a shear-localization zone at the tertiary stage.The strain-time responses inside and outside the localization zone are characterized by local strain accumulation and inelastic unloading during the secondary and tertiary stages,respectively.The width of the shear-localization zone is found to range from 4.43 mm to 7.08 mm and increased with a longer time-to-failure.Scanning electron microscopy(SEM)reveals a dominant coalescence of intergranular cracks on the fracture surface,and the degree of physiochemical deterioration caused by water-rock interaction is more severe under a longer lifetime.The brittle sandstone’s time-dependent deformation is essentially controlled by microcrack development during generalized relaxation,and its expectancy-life is determined by its initial microstructural state and the rheological path.
