It’s never too early in the year to start planning a break from the stress of city life,and southwest China’s charming Guizhou Province is a destination that should be right at the top of your list.
The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ...The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ simulations with varied protocols to evaluate the effectiveness of different descriptors in predicting mechanical properties across both low-and high-pressure regimes.Our findings demonstrate that conventional structural and configurational descriptors fail to correlate with the mechanical response following pressure release,whereas the activation energy descriptor exhibits robust linearity with shear modulus after correcting for pressure effects.Notably,the soft mode parameter emerges as an ideal and computationally efficient alternative for capturing this mechanical behavior.These findings provide critical insights into the influence of pressure on glassy properties,integrating the distinct features of compressed glasses into a unified theoretical framework.展开更多
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
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
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
All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid...All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid electrolyte plays a vital role in the performance of working ASSLBs,which is challenging to investigate quantitatively by experimental approach.This work proposed a quantitative model based on the finite element method for electrochemical impedance spectroscopy simulation of different solid-solid contact states in ASSLBs.With the assistance of an equivalent circuit model and distribution of relaxation times,it is discovered that as the number of voids and the sharpness of cracks increase,the contact resistance Rcgrows and ultimately dominates the battery impedance.Through accurate fitting,inverse proportional relations between contact resistance Rcand(1-porosity)as well as crack angle was disclosed.This contribution affords a fresh insight into clarifying solid-solid contact states in ASSLBs.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
Introduction Pure NBT exhibits the frequency-dependent Curie temperature,indicating that its dielectric properties are affected by temperature,measurement frequency,and material processing condition.To enhance the die...Introduction Pure NBT exhibits the frequency-dependent Curie temperature,indicating that its dielectric properties are affected by temperature,measurement frequency,and material processing condition.To enhance the dielectric and relaxor properties of NBT,various dopants such as Sr,K,Li and Bi are incorporated into the NBT structure.These modifications significantly alter the dielectric constant and relaxation behavior,demonstrating a dominant influence of dopant on the material properties.Among these,the solid solution of BaTiO_(3)(BT)with NBT is widely investigated due to its ability to stabilize the perovskite structure and improve dielectric performance.However,the temperature-dependent stability of dielectric properties remains a critical challenge for high-temperature applications.In this study,(1-x)(0.75Na_(0.5)Bi_(0.5)TiO_(3)-0.25BaTiO_(3))-xBaZrO_(3)(NBT-BT-xBZ,x=0,0.08,0.14,and 0.20)ceramics were prepared by a solid-state reaction method.The effect of BaZrO_(3)(BZ)addition on the structural,dielectric,and energy storage properties was systematically investigated.In addition,the phase transition and relaxation behaviors were also analyzed based on the modified Curie-Weiss law,Vogel-Fulcher relation,and Lorentz-type empirical law.Methods The starting materials were powders of high purity Na_(2)CO_(3),Bi_(2)O_(3),TiO_(2),BaCO_(3),and ZrO_(2).The powders were weighed according to a stoichiometric ratio(with 1%excess of Na and Bi)and ground with ethanol in a ball mill at 300 r/min for more than 12 h,and the weight ratio of raw material to ethanol and zirconium balls was 1:1:2.The dried material was heat-treated at 850℃ for 2 h to promote the formation of NBT-BT-BZ.After further grinding for 12 h,the samples were mixed with a small amount of polyvinyl alcohol(PVA).The samples were sintered in air at 1150℃for 2 h and cooled to room temperature.The phase composition of the ceramic samples was determined by an model D8 ADVANDCE X-ray diffractometer(D8 ADVANDCEXRD,Bruker AXS Ltd.,Germany)with Cu target Kαrays,at X-ray wavelengthλof 1.5406Å,2θin the range of 10°to 80°,applied voltage of 40 kV,and a current of 500 mA.A silver paste was coated on the two surfaces as electrodes and heat-treated at 700℃ for 10 min.The dielectric properties of the ceramic samples were determined at different frequencies by a model DMS-1000 high-temperature dielectric temperature spectroscope(BALAB Tech.Co.,China)with at a ramp rate of 3(°)/min in a temperature range from room temperature to 450℃.The overdamped(200Ω)discharge tests for bulk ceramic samples were performed by a model CFD-005 discharge tester(Gogo(GG)Instruments Technology,China)).Results and discussion The XRD patterns indicate that all the ceramic samples have a perovskite structure without any detectable secondary phase,proving that zirconium ions can completely enter the lattice and form a solid solution.Based on the locally magnified XRD peaks,the XRD peak shape shifts towards lower angles as a whole as the BZ content increases.This indicates that the overall volume of the crystal cell shows an expansion as the Zr ions replace Ti ions due to different ionic radii of Zr and Ti ions.The SEM images show that the grain size gradually increases with increasing the BZ content.The addition of BZ promotes the grain growth.However,this gradually slows down with the increase of content up to x of 0.20.The limited grain size variation appears in the latter two samples.All the samples show a relatively dense morphology.The Curie temperature of the NBT-0.25BT ceramic samples is 256℃,which is similar to the reported results.The Curie temperature decreases gradually with the increase of BZ additive,and the dielectric temperature spectrum flattens out,indicating that the enhanced structural and temperature stability of the NBT-BT-BZ ceramics.The maximum values of all dielectric constants correspond to temperatures that increase with frequency,indicating a dielectric relaxor behavior.A frequency dispersion is accompanied at near the Curie temperature,which can be ascribed to the thermal evolution of the tetragonal polar nanoregions(PNRs)and the mixing effect of the transition from tripartite to tetragonal PNRs.Theγvalues obtained from the experimental data at 100 kHz are 1.79,1.83,1.89,and 1.92 for NBT-BT,NBT-BT-0.08BZ,NBT-BT-0.14BZ,and NBT-BT-0.20BZ,respectively.Theγvalue increases gradually with the addition of the BZ content,showing an enhanced relaxation of the NBT-BT-BZ ceramics.The comparison of discharge current curves and energy density of all the ceramics indicate that the addition of BZ significantly improves the discharge current and energy storage performance.A high discharging energy density(Wd)of 1.6 J·cm^(-3) with a fast discharging speed(τ0.9)of 75 ns is obtained for the ceramic samples with x of 0.14.This can be attributed to an increased relaxation as the BZ content increases.Conclusions NBT-BT-BZ ceramics were prepared by a solid-state reaction method.The XRD patterns revealed a phase transition from a tetragonal phase to a pseudocubic phase as the BZ content increased.The dielectric relaxation behavior of the ceramics could be described by three empirical laws(i.e.,modified Curie-Weiss law,Vogel-Fulcher relation and Lorentz-type empirical law).The dielectric relaxation followed the modified Curie-Weiss law and the Vogel-Fulcher relationship.The parametersγand Ea,which were obtained to evaluate the relaxation behavior,increased at a higher BZ content.The Lorentz-type relationship effectively described the temperature dependence of the dielectric constant on both the low-and high-temperature sides within a specific temperature range for all the ceramics.展开更多
In this paper,we introduce the real pairwise completely positive(RPCP)matrices with one of them is necessarily positive semidefinite while the other one is necessarily entrywise nonnegative,which has a real pairwise c...In this paper,we introduce the real pairwise completely positive(RPCP)matrices with one of them is necessarily positive semidefinite while the other one is necessarily entrywise nonnegative,which has a real pairwise completely positive(RPCP)decomposition.We study the properties of RPCP matrices and give some necessary and sufficient conditions for a matrix pair to be RPCP.First,we give an equivalent decomposition for the RPCP matrices,which is different from the RPCP-decomposition and show that the matrix pair(X,X)is RPCP if and only if X is completely positive.Besides,we also prove that the RPCP matrices checking problem is equivalent to the separable completion problem.A semidefinite algorithm is also proposed for detecting whether or not a matrix pair is RPCP.The asymptotic and finite convergence of the algorithm are also discussed.If it is RPCP,we can further give a RPCP-decomposition for it;if it is not,we can obtain a certificate for this.展开更多
The dynamics of biomolecules span across a wide range of timescales,reflecting the complexity of free energy landscapes of biomolecules.Among these,the microsecond-tomillisecond(μs-ms)timescale dynamics are particula...The dynamics of biomolecules span across a wide range of timescales,reflecting the complexity of free energy landscapes of biomolecules.Among these,the microsecond-tomillisecond(μs-ms)timescale dynamics are particularly significant,offering detailed insights into the kinetic,thermodynamic,and structural aspects of biological function.Many critical biological processes,including enzyme catalysis,protein folding,ligand binding,and allosteric regulation,operate within this timescale.Nuclear magnetic resonance(NMR)spectroscopy is a powerful technique for probing molecular dynamics in this time window,commonly used NMR methods for investigatingμs-ms timescale dynamics include Carr-Purcell-Meiboom-Gill(CPMG)relaxation dispersion,chemical exchange saturation transfer(CEST),and rotating-frame longitudinal relaxation dispersion(R_(1ρ)relaxation dispersion).This review provides a brief ove rview of the fundamental principles and some recent advances of these methods,highlighting their interrelationships and applications in elucidating biomolecular dynamics.展开更多
The heavy-atom effect of halogen(Br and I)has been widely employed for boosting spin-crossover in organic molecules,while recent investigation indicated halogen-substitution can also enhance fluorescence and even lead...The heavy-atom effect of halogen(Br and I)has been widely employed for boosting spin-crossover in organic molecules,while recent investigation indicated halogen-substitution can also enhance fluorescence and even lead to aggregation-induced emission(AIE).In this work,we investigated ultrafast excited state dynamics of a halogen-substituted model system,i.e.squaryliums NSQ-R(R=H,Cl,Br,I),by using femtosecond spectroscopy and theoretical approach.Fast external reorganization(Ex-re,~3 ps)and slow internal reorganization(In-re,5-20 ps)were observed,while quantitative fitting indicated halogen-substitution leads to a slower non-radiative S1→S0 decay(k_(NR)^(s))and subsequently enhanced fluorescence emitting.By analyzing the extracted k_(NR)^(s)within theoretical framework of non-radiative transition in the strong coupling regime,a plausible AIE mechanism of NSQs was revealed.Our work provides a clear picture on non-radiative dynamics of halogen-substituted squaryliums,which might be useful for future development of organic dyes.展开更多
Metallic glasses(MGs),a metastable material far from equilibrium,exhibit intricate dynamic relaxation behaviors.The challenge lies in developing a model that accurately describes the dynamics and deforma-tion mechanis...Metallic glasses(MGs),a metastable material far from equilibrium,exhibit intricate dynamic relaxation behaviors.The challenge lies in developing a model that accurately describes the dynamics and deforma-tion mechanisms of MG.This paper introduces a model integrating dynamic relaxation with deformation behavior.Validation through dynamic mechanical analysis,stress relaxation,creep,and strain recovery tests confirm the existence of four deformation modes:elasticity,anelasticity fromβrelaxation,anelas-ticity fromαrelaxation at low temperatures,and viscoplasticity fromαrelaxation at high temperatures.The model captures all of these deformation modes.The dynamical mechanical spectrum and stress re-laxation spectrum unveil dynamic features during glass to liquid transition,and a simple and effective experimental method was developed for identifying ultra-low-frequency dynamic relaxation.This work provides new perspectives on the study of relaxation dynamics in glassy states and establishes impor-tant connections between dynamic relaxation behavior and deformation mechanisms.These findings lay a theoretical and experimental foundation for the broad application of MGs.展开更多
Collision-induced re-laxation process of CH(X^(2)Π,v=0)radical in various bath gases He,Ar,and N_(2)has been investigated ex-perimentally under low-temperature(26-52 K)supersonic flow conditions.The CH radicals were ...Collision-induced re-laxation process of CH(X^(2)Π,v=0)radical in various bath gases He,Ar,and N_(2)has been investigated ex-perimentally under low-temperature(26-52 K)supersonic flow conditions.The CH radicals were generat-ed with internal excitation by multiphoton photolysis of CHBr_(3)at 248 nm,and its rotational temperature was found to relax to the flow temperature in a few microseconds by colliding with bath gas.The relaxation rate coefficients for CH(X^(2)Π,v=0)radical in He,Ar,and N_(2)flow were obtained by time-resolved laser-induced fluorescence measurements,ranging from 10^(-12)cm^(3)·molecule^(-1)·s^(-1)to 10^(-11)cm^(3)·molecule^(-1)·s^(-1).The N_(2)flow exhibits the highest relax-ation rate for CH(X^(2)Π)radical due to its additional rovibrational levels,which allow for more efficient energy dissipation during collisions compared to monoatomic gases.The Ar flow shows a larger relaxation rate than He flow due to its greater polarizability and stronger long-range interaction with the CH(X^(2)Π)radical.展开更多
Objectives:The objective of this study was to assess the impact of two relaxation techniques,the Jacobson’s progressive muscle relaxation technique(JPMR),and the Benson’s relaxation technique(BRT),on the levels of s...Objectives:The objective of this study was to assess the impact of two relaxation techniques,the Jacobson’s progressive muscle relaxation technique(JPMR),and the Benson’s relaxation technique(BRT),on the levels of stress and anxiety experienced by patients undergoing coronary angioplasty.Materials and Methods:Quantitative research approach with quasi-experimental pre-test and posttest control group design was conducted with seventy coronary angioplasty patients from the Institute of Medical Science,and SUM Hospital,Bhubaneswar,Odisha.The participants were purposively selected and divided into Experimental Group 1(n=35)and Experimental Group 2(n=35).Each group received either BRT or JPMR for three consecutive days.Pretest and posttest data were collected using a structured demographic questionnaire and the modified depression anxiety stress scale-21.Results:Both BRT and JPMR significantly decreased the levels of stress and anxiety among patients undergoing angioplasty compared to baseline(P<0.05).However,there was no significant difference between the two techniques based on Fisher’s exact P value.This suggests that both interventions are effective in reducing stress and anxiety among angioplasty patients.Conclusion:BRT or JPMR are noninvasive,nonpharmacological interventions that effectively reduce stress and anxiety in patients undergoing angioplasty.These findings underscore the importance of incorporating relaxation techniques into nursing practice and hospital programs to enhance patient care and promote holistic well-being post-angioplasty.展开更多
Objective:The study aimed to investigate the effect of relaxation techniques in reducing fear and anxiety in patients in need of general surgery.Materials and Methods:This quasi-experimental study with a pre-post cont...Objective:The study aimed to investigate the effect of relaxation techniques in reducing fear and anxiety in patients in need of general surgery.Materials and Methods:This quasi-experimental study with a pre-post control group design was conducted on 120 patients requiring general surgery at Saman Al-Hojjaj Hospital in Sirjan County.Patients were selected using convenience sampling and randomly assigned to the intervention group(n=60)and control group(n=60).The intervention group was taught box breathing and progressive muscle relaxation techniques by a senior psychiatric nursing expert for 15-20 min every 4 h until surgery.The control group received routine care for surgery.Data on fear and anxiety outcomes were collected using the Spielberger State-Trait Anxiety Inventory and the Surgical Fear Questionnaire.Results:The intervention group had a mean total fear score of 29.27±12.69 compared to 37.20±16.39 in the control group(P=0.012),with significant reductions in both short-term(13.57±5.93 vs.15.98±8.90;P=0.209,Cohen’s d=0.32)and long-term(15.70±7.19 vs.21.22±9.11;P=0.001,Cohen’s d=0.66)fear components(total fear:P=0.012,Cohen’s d=0.54).The total anxiety score was 91.88±6.28 in the control group and 93.60±3.62 in the intervention group,with trait anxiety significantly reduced in the intervention group(P=0.039,Cohen’s d=0.41)postintervention,but no significant change in state anxiety(P=0.577,Cohen’s d=0.16).Conclusions:Relaxation techniques significantly alleviate preoperative psychological distress,effectively reducing fear and anxiety in general surgery patients.These cost-effective,non-invasive methods enhance recovery and reduce healthcare costs.We recommend training healthcare providers to implement these techniques for optimal patient outcomes.展开更多
Stress relaxation is a time-dependent phenomenon in rocks,characterized by a gradual decrease in stress magnitude while strain remains constant with time.This study introduces a novel experimental approach to investig...Stress relaxation is a time-dependent phenomenon in rocks,characterized by a gradual decrease in stress magnitude while strain remains constant with time.This study introduces a novel experimental approach to investigate deformation processes during the primary and secondary stages of stress relaxation and to differentiate the damage mechanisms occurring during relaxation from those under monotonic loading.To this end,the deformation behavior of prismatic-shaped homogeneous Stanstead granite(SG)rock specimens was monitored using two-dimensional digital image correlation(2D-DIC)in-sync with active ultrasonic sensing during stress relaxation and monotonic loading conditions.In particular,the SG specimens were allowed to undergo stress relaxation starting at a driving stress(σd)just above the crack damage(CD)threshold of the specimens,while their deformation characteristics were evaluated via 2D-DIC full-field strain maps and ultrasonic characteristics.The results indicate that the primary stage of relaxation is marked by accumulation of tensile damage at a decreasing rate,and the rate of damage accumulation reaches a steady state during the secondary stage of relaxation.Likewise,the ultrasonic amplitude reduced at a decreasing rate during the primary stage of relaxation and attained a constant rate of reduction during secondary relaxation.Additionally,a comparison of rock behavior during stress relaxation and monotonic loading conditions quantitatively demonstrated that SG dilates more during relaxation than under monotonic loading over a given range of damage values.This is interpreted to be associated with the fact that local extensional strains are diffuse under relaxation,in contrast with the more localized nature of damage under monotonic loading conditions.展开更多
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
A comprehensive analysis was performed on 30 healthy female participants to assess the impact of fragranced body washes on mood improvement.The study examined their objective electroencephalographic (EEG) changes and ...A comprehensive analysis was performed on 30 healthy female participants to assess the impact of fragranced body washes on mood improvement.The study examined their objective electroencephalographic (EEG) changes and subjective feedback before and after using the fragranced products.The results showed that both the alpha and theta band activities of the participants increased significantly after using body washes,especially in the occipito-parietal and frontal area of brain,indicating that their brains were at a higher level of stability and relaxation.Meanwhile,in terms of subjective evaluation,the participants’ subjective feelings such as calmness,relaxation,tranquility,and calmness were significantly enhanced.This study has revealed the efficacy of fragranced products in improving mood and is expected to provide support for the development and application of fragranced products.展开更多
文摘It’s never too early in the year to start planning a break from the stress of city life,and southwest China’s charming Guizhou Province is a destination that should be right at the top of your list.
基金supported by the National Natural Science Foundation of China (Grant Nos.T2325004 and 52161160330)the National Natural Science Foundation of China (Grants No.12504233)+2 种基金Advanced MaterialsNational Science and Technology Major Project (Grant No.2024ZD0606900)the Talent Hub for “AI+New Materials” Basic Researchthe Key Research and Development Program of Ningbo (Grant No.2025Z088)。
文摘The functional properties of glasses are governed by their formation history and the complex relaxation processes they undergo.However,under extreme conditions,glass behaviors are still elusive.In this study,we employ simulations with varied protocols to evaluate the effectiveness of different descriptors in predicting mechanical properties across both low-and high-pressure regimes.Our findings demonstrate that conventional structural and configurational descriptors fail to correlate with the mechanical response following pressure release,whereas the activation energy descriptor exhibits robust linearity with shear modulus after correcting for pressure effects.Notably,the soft mode parameter emerges as an ideal and computationally efficient alternative for capturing this mechanical behavior.These findings provide critical insights into the influence of pressure on glassy properties,integrating the distinct features of compressed glasses into a unified theoretical framework.
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 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 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supported by the Beijing Natural Science Foundation(Z200011,L233004)the National Key Research and Development Program(2021YFB2500300)+3 种基金the National Natural Science Foundation of China(52394170,52394171,22109011,22393900,and 22108151)the Tsinghua-Jiangyin Innovation Special Fund(TJISF)(2022JYTH0101)the S&T Program of Hebei(22344402D)the Tsinghua University Initiative Scientific Research Program.
文摘All-solid-state lithium batteries(ASSLBs)are strongly considered as the next-generation energy storage devices for their high energy density and intrinsic safety.The solid-solid contact between lithium metal and solid electrolyte plays a vital role in the performance of working ASSLBs,which is challenging to investigate quantitatively by experimental approach.This work proposed a quantitative model based on the finite element method for electrochemical impedance spectroscopy simulation of different solid-solid contact states in ASSLBs.With the assistance of an equivalent circuit model and distribution of relaxation times,it is discovered that as the number of voids and the sharpness of cracks increase,the contact resistance Rcgrows and ultimately dominates the battery impedance.Through accurate fitting,inverse proportional relations between contact resistance Rcand(1-porosity)as well as crack angle was disclosed.This contribution affords a fresh insight into clarifying solid-solid contact states in ASSLBs.
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.
基金国家自然科学基金(12104188,12474095 and 52402323)开放基金(2023KF03,KYCX24-4102)。
文摘Introduction Pure NBT exhibits the frequency-dependent Curie temperature,indicating that its dielectric properties are affected by temperature,measurement frequency,and material processing condition.To enhance the dielectric and relaxor properties of NBT,various dopants such as Sr,K,Li and Bi are incorporated into the NBT structure.These modifications significantly alter the dielectric constant and relaxation behavior,demonstrating a dominant influence of dopant on the material properties.Among these,the solid solution of BaTiO_(3)(BT)with NBT is widely investigated due to its ability to stabilize the perovskite structure and improve dielectric performance.However,the temperature-dependent stability of dielectric properties remains a critical challenge for high-temperature applications.In this study,(1-x)(0.75Na_(0.5)Bi_(0.5)TiO_(3)-0.25BaTiO_(3))-xBaZrO_(3)(NBT-BT-xBZ,x=0,0.08,0.14,and 0.20)ceramics were prepared by a solid-state reaction method.The effect of BaZrO_(3)(BZ)addition on the structural,dielectric,and energy storage properties was systematically investigated.In addition,the phase transition and relaxation behaviors were also analyzed based on the modified Curie-Weiss law,Vogel-Fulcher relation,and Lorentz-type empirical law.Methods The starting materials were powders of high purity Na_(2)CO_(3),Bi_(2)O_(3),TiO_(2),BaCO_(3),and ZrO_(2).The powders were weighed according to a stoichiometric ratio(with 1%excess of Na and Bi)and ground with ethanol in a ball mill at 300 r/min for more than 12 h,and the weight ratio of raw material to ethanol and zirconium balls was 1:1:2.The dried material was heat-treated at 850℃ for 2 h to promote the formation of NBT-BT-BZ.After further grinding for 12 h,the samples were mixed with a small amount of polyvinyl alcohol(PVA).The samples were sintered in air at 1150℃for 2 h and cooled to room temperature.The phase composition of the ceramic samples was determined by an model D8 ADVANDCE X-ray diffractometer(D8 ADVANDCEXRD,Bruker AXS Ltd.,Germany)with Cu target Kαrays,at X-ray wavelengthλof 1.5406Å,2θin the range of 10°to 80°,applied voltage of 40 kV,and a current of 500 mA.A silver paste was coated on the two surfaces as electrodes and heat-treated at 700℃ for 10 min.The dielectric properties of the ceramic samples were determined at different frequencies by a model DMS-1000 high-temperature dielectric temperature spectroscope(BALAB Tech.Co.,China)with at a ramp rate of 3(°)/min in a temperature range from room temperature to 450℃.The overdamped(200Ω)discharge tests for bulk ceramic samples were performed by a model CFD-005 discharge tester(Gogo(GG)Instruments Technology,China)).Results and discussion The XRD patterns indicate that all the ceramic samples have a perovskite structure without any detectable secondary phase,proving that zirconium ions can completely enter the lattice and form a solid solution.Based on the locally magnified XRD peaks,the XRD peak shape shifts towards lower angles as a whole as the BZ content increases.This indicates that the overall volume of the crystal cell shows an expansion as the Zr ions replace Ti ions due to different ionic radii of Zr and Ti ions.The SEM images show that the grain size gradually increases with increasing the BZ content.The addition of BZ promotes the grain growth.However,this gradually slows down with the increase of content up to x of 0.20.The limited grain size variation appears in the latter two samples.All the samples show a relatively dense morphology.The Curie temperature of the NBT-0.25BT ceramic samples is 256℃,which is similar to the reported results.The Curie temperature decreases gradually with the increase of BZ additive,and the dielectric temperature spectrum flattens out,indicating that the enhanced structural and temperature stability of the NBT-BT-BZ ceramics.The maximum values of all dielectric constants correspond to temperatures that increase with frequency,indicating a dielectric relaxor behavior.A frequency dispersion is accompanied at near the Curie temperature,which can be ascribed to the thermal evolution of the tetragonal polar nanoregions(PNRs)and the mixing effect of the transition from tripartite to tetragonal PNRs.Theγvalues obtained from the experimental data at 100 kHz are 1.79,1.83,1.89,and 1.92 for NBT-BT,NBT-BT-0.08BZ,NBT-BT-0.14BZ,and NBT-BT-0.20BZ,respectively.Theγvalue increases gradually with the addition of the BZ content,showing an enhanced relaxation of the NBT-BT-BZ ceramics.The comparison of discharge current curves and energy density of all the ceramics indicate that the addition of BZ significantly improves the discharge current and energy storage performance.A high discharging energy density(Wd)of 1.6 J·cm^(-3) with a fast discharging speed(τ0.9)of 75 ns is obtained for the ceramic samples with x of 0.14.This can be attributed to an increased relaxation as the BZ content increases.Conclusions NBT-BT-BZ ceramics were prepared by a solid-state reaction method.The XRD patterns revealed a phase transition from a tetragonal phase to a pseudocubic phase as the BZ content increased.The dielectric relaxation behavior of the ceramics could be described by three empirical laws(i.e.,modified Curie-Weiss law,Vogel-Fulcher relation and Lorentz-type empirical law).The dielectric relaxation followed the modified Curie-Weiss law and the Vogel-Fulcher relationship.The parametersγand Ea,which were obtained to evaluate the relaxation behavior,increased at a higher BZ content.The Lorentz-type relationship effectively described the temperature dependence of the dielectric constant on both the low-and high-temperature sides within a specific temperature range for all the ceramics.
文摘In this paper,we introduce the real pairwise completely positive(RPCP)matrices with one of them is necessarily positive semidefinite while the other one is necessarily entrywise nonnegative,which has a real pairwise completely positive(RPCP)decomposition.We study the properties of RPCP matrices and give some necessary and sufficient conditions for a matrix pair to be RPCP.First,we give an equivalent decomposition for the RPCP matrices,which is different from the RPCP-decomposition and show that the matrix pair(X,X)is RPCP if and only if X is completely positive.Besides,we also prove that the RPCP matrices checking problem is equivalent to the separable completion problem.A semidefinite algorithm is also proposed for detecting whether or not a matrix pair is RPCP.The asymptotic and finite convergence of the algorithm are also discussed.If it is RPCP,we can further give a RPCP-decomposition for it;if it is not,we can obtain a certificate for this.
基金financially supported by funds from the Natural Science Foundation of Beijing Municipality(Grant Number 7232251)the National Natural Science Foundation of China(Grant Number 22474006)。
文摘The dynamics of biomolecules span across a wide range of timescales,reflecting the complexity of free energy landscapes of biomolecules.Among these,the microsecond-tomillisecond(μs-ms)timescale dynamics are particularly significant,offering detailed insights into the kinetic,thermodynamic,and structural aspects of biological function.Many critical biological processes,including enzyme catalysis,protein folding,ligand binding,and allosteric regulation,operate within this timescale.Nuclear magnetic resonance(NMR)spectroscopy is a powerful technique for probing molecular dynamics in this time window,commonly used NMR methods for investigatingμs-ms timescale dynamics include Carr-Purcell-Meiboom-Gill(CPMG)relaxation dispersion,chemical exchange saturation transfer(CEST),and rotating-frame longitudinal relaxation dispersion(R_(1ρ)relaxation dispersion).This review provides a brief ove rview of the fundamental principles and some recent advances of these methods,highlighting their interrelationships and applications in elucidating biomolecular dynamics.
基金support by the National Key R&D Program of China(Nos.2020YFA0714603 and 2020YFA0714604)。
文摘The heavy-atom effect of halogen(Br and I)has been widely employed for boosting spin-crossover in organic molecules,while recent investigation indicated halogen-substitution can also enhance fluorescence and even lead to aggregation-induced emission(AIE).In this work,we investigated ultrafast excited state dynamics of a halogen-substituted model system,i.e.squaryliums NSQ-R(R=H,Cl,Br,I),by using femtosecond spectroscopy and theoretical approach.Fast external reorganization(Ex-re,~3 ps)and slow internal reorganization(In-re,5-20 ps)were observed,while quantitative fitting indicated halogen-substitution leads to a slower non-radiative S1→S0 decay(k_(NR)^(s))and subsequently enhanced fluorescence emitting.By analyzing the extracted k_(NR)^(s)within theoretical framework of non-radiative transition in the strong coupling regime,a plausible AIE mechanism of NSQs was revealed.Our work provides a clear picture on non-radiative dynamics of halogen-substituted squaryliums,which might be useful for future development of organic dyes.
基金supported by the National Natu-ral Science Foundation of China(Nos.12472069 and 52271153)the Natural Science Basic Research Plan for Distinguished Young Scholars in Shaanxi Province(No.2021JC-12)+5 种基金Guo-Jian Lyu is supported by the National Natural Science Foundation of China(No.52301219)the Fundamental Research Funds for the Cen-tral Universities(No.5000230147)Yun-Jiang Wang was finan-cially supported by the National Natural Science Foundation of China(No.12472112)Y.Yang acknowledges financial support from the Research Grant Council(RGC),the Hong Kong Government through the General Research Fund(GRF)(Nos.CityU11206362 and N_CityU109/21)E.Pineda acknowledges financial support from MCIN/AEI(Nos.PID2020-112975GB-I00/10.13039/501100011033 and CEX2023-001300-M/10.13039/501100011033)Generalitat de Catalunya(No.2021SGR00343).
文摘Metallic glasses(MGs),a metastable material far from equilibrium,exhibit intricate dynamic relaxation behaviors.The challenge lies in developing a model that accurately describes the dynamics and deforma-tion mechanisms of MG.This paper introduces a model integrating dynamic relaxation with deformation behavior.Validation through dynamic mechanical analysis,stress relaxation,creep,and strain recovery tests confirm the existence of four deformation modes:elasticity,anelasticity fromβrelaxation,anelas-ticity fromαrelaxation at low temperatures,and viscoplasticity fromαrelaxation at high temperatures.The model captures all of these deformation modes.The dynamical mechanical spectrum and stress re-laxation spectrum unveil dynamic features during glass to liquid transition,and a simple and effective experimental method was developed for identifying ultra-low-frequency dynamic relaxation.This work provides new perspectives on the study of relaxation dynamics in glassy states and establishes impor-tant connections between dynamic relaxation behavior and deformation mechanisms.These findings lay a theoretical and experimental foundation for the broad application of MGs.
基金supported by the National Natural Science Foundation of China(No.22273103)the National Natural Science Foundation of China(NSFC Center for Chemical Dynamics)(No.22288201)+1 种基金Dalian Institute of Chemical Physics(DICP I202230)the Scientific Instrument Developing Project of the Chinese Academy of Sciences(grant GJJSTD20220001)。
文摘Collision-induced re-laxation process of CH(X^(2)Π,v=0)radical in various bath gases He,Ar,and N_(2)has been investigated ex-perimentally under low-temperature(26-52 K)supersonic flow conditions.The CH radicals were generat-ed with internal excitation by multiphoton photolysis of CHBr_(3)at 248 nm,and its rotational temperature was found to relax to the flow temperature in a few microseconds by colliding with bath gas.The relaxation rate coefficients for CH(X^(2)Π,v=0)radical in He,Ar,and N_(2)flow were obtained by time-resolved laser-induced fluorescence measurements,ranging from 10^(-12)cm^(3)·molecule^(-1)·s^(-1)to 10^(-11)cm^(3)·molecule^(-1)·s^(-1).The N_(2)flow exhibits the highest relax-ation rate for CH(X^(2)Π)radical due to its additional rovibrational levels,which allow for more efficient energy dissipation during collisions compared to monoatomic gases.The Ar flow shows a larger relaxation rate than He flow due to its greater polarizability and stronger long-range interaction with the CH(X^(2)Π)radical.
文摘Objectives:The objective of this study was to assess the impact of two relaxation techniques,the Jacobson’s progressive muscle relaxation technique(JPMR),and the Benson’s relaxation technique(BRT),on the levels of stress and anxiety experienced by patients undergoing coronary angioplasty.Materials and Methods:Quantitative research approach with quasi-experimental pre-test and posttest control group design was conducted with seventy coronary angioplasty patients from the Institute of Medical Science,and SUM Hospital,Bhubaneswar,Odisha.The participants were purposively selected and divided into Experimental Group 1(n=35)and Experimental Group 2(n=35).Each group received either BRT or JPMR for three consecutive days.Pretest and posttest data were collected using a structured demographic questionnaire and the modified depression anxiety stress scale-21.Results:Both BRT and JPMR significantly decreased the levels of stress and anxiety among patients undergoing angioplasty compared to baseline(P<0.05).However,there was no significant difference between the two techniques based on Fisher’s exact P value.This suggests that both interventions are effective in reducing stress and anxiety among angioplasty patients.Conclusion:BRT or JPMR are noninvasive,nonpharmacological interventions that effectively reduce stress and anxiety in patients undergoing angioplasty.These findings underscore the importance of incorporating relaxation techniques into nursing practice and hospital programs to enhance patient care and promote holistic well-being post-angioplasty.
基金funded by Sirjan Medical Sciences Faculty,Sirjan,Iran.(Project code:402000018).
文摘Objective:The study aimed to investigate the effect of relaxation techniques in reducing fear and anxiety in patients in need of general surgery.Materials and Methods:This quasi-experimental study with a pre-post control group design was conducted on 120 patients requiring general surgery at Saman Al-Hojjaj Hospital in Sirjan County.Patients were selected using convenience sampling and randomly assigned to the intervention group(n=60)and control group(n=60).The intervention group was taught box breathing and progressive muscle relaxation techniques by a senior psychiatric nursing expert for 15-20 min every 4 h until surgery.The control group received routine care for surgery.Data on fear and anxiety outcomes were collected using the Spielberger State-Trait Anxiety Inventory and the Surgical Fear Questionnaire.Results:The intervention group had a mean total fear score of 29.27±12.69 compared to 37.20±16.39 in the control group(P=0.012),with significant reductions in both short-term(13.57±5.93 vs.15.98±8.90;P=0.209,Cohen’s d=0.32)and long-term(15.70±7.19 vs.21.22±9.11;P=0.001,Cohen’s d=0.66)fear components(total fear:P=0.012,Cohen’s d=0.54).The total anxiety score was 91.88±6.28 in the control group and 93.60±3.62 in the intervention group,with trait anxiety significantly reduced in the intervention group(P=0.039,Cohen’s d=0.41)postintervention,but no significant change in state anxiety(P=0.577,Cohen’s d=0.16).Conclusions:Relaxation techniques significantly alleviate preoperative psychological distress,effectively reducing fear and anxiety in general surgery patients.These cost-effective,non-invasive methods enhance recovery and reduce healthcare costs.We recommend training healthcare providers to implement these techniques for optimal patient outcomes.
基金support provided by the Indian Institute of Technology Delhi,India,and Colorado School of Mines,USA,for performing the work related to this research article is greatly appreciatedsupported by the IIT Delhi MFIRP Grant No.MI022762G+1 种基金partially by the U.S.Department of Energy,Office of Basic Energy Sciences,under Award Number DE-SC0019117support is gratefully acknowledged。
文摘Stress relaxation is a time-dependent phenomenon in rocks,characterized by a gradual decrease in stress magnitude while strain remains constant with time.This study introduces a novel experimental approach to investigate deformation processes during the primary and secondary stages of stress relaxation and to differentiate the damage mechanisms occurring during relaxation from those under monotonic loading.To this end,the deformation behavior of prismatic-shaped homogeneous Stanstead granite(SG)rock specimens was monitored using two-dimensional digital image correlation(2D-DIC)in-sync with active ultrasonic sensing during stress relaxation and monotonic loading conditions.In particular,the SG specimens were allowed to undergo stress relaxation starting at a driving stress(σd)just above the crack damage(CD)threshold of the specimens,while their deformation characteristics were evaluated via 2D-DIC full-field strain maps and ultrasonic characteristics.The results indicate that the primary stage of relaxation is marked by accumulation of tensile damage at a decreasing rate,and the rate of damage accumulation reaches a steady state during the secondary stage of relaxation.Likewise,the ultrasonic amplitude reduced at a decreasing rate during the primary stage of relaxation and attained a constant rate of reduction during secondary relaxation.Additionally,a comparison of rock behavior during stress relaxation and monotonic loading conditions quantitatively demonstrated that SG dilates more during relaxation than under monotonic loading over a given range of damage values.This is interpreted to be associated with the fact that local extensional strains are diffuse under relaxation,in contrast with the more localized nature of damage under monotonic loading conditions.
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.
文摘A comprehensive analysis was performed on 30 healthy female participants to assess the impact of fragranced body washes on mood improvement.The study examined their objective electroencephalographic (EEG) changes and subjective feedback before and after using the fragranced products.The results showed that both the alpha and theta band activities of the participants increased significantly after using body washes,especially in the occipito-parietal and frontal area of brain,indicating that their brains were at a higher level of stability and relaxation.Meanwhile,in terms of subjective evaluation,the participants’ subjective feelings such as calmness,relaxation,tranquility,and calmness were significantly enhanced.This study has revealed the efficacy of fragranced products in improving mood and is expected to provide support for the development and application of fragranced products.
