Luminescent metal-organic frameworks(MOFs)have garnered significant attention due to their structural tunability and potential applications in solid-state lighting,bioimaging,sensing,anticounterfeiting,and other field...Luminescent metal-organic frameworks(MOFs)have garnered significant attention due to their structural tunability and potential applications in solid-state lighting,bioimaging,sensing,anticounterfeiting,and other fields.Nevertheless,due to the tendency of1,4-benzenedicarboxylic acid(BDC)to rotate within the framework,MOFs composed of it exhibit significant non-radiative energy dissipation and thus impair the emissive properties.In this study,efficient luminescence of MIL-140A nanocrystals(NCs)with BDC rotors as ligands is achieved by pressure treatment strategy.Pressure treatment effectively modulates the pore structure of the framework,enhancing the interactions between the N,N-dimethylformamide vip molecules and the BDC ligands.The enhanced host-vip interaction contributes to the structural rigidity of the MOF,thereby suppressing the rotation-induced excited-state energy loss.As a result,the pressure-treated MIL-140A NCs displayed bright blue-light emission,with the photoluminescence quantum yield increasing from an initial 6.8%to 69.2%.This study developed an effective strategy to improve the luminescence performance of rotor ligand MOFs,offers a new avenue for the rational design and synthesis of MOFs with superior luminescent properties.展开更多
Combustion dynamics are a critical factor in determining the performance and reliabilityof a chemical propulsion engine.The underlying processes include liquid atomization,evaporation,mixing,and chemical reactions.Thi...Combustion dynamics are a critical factor in determining the performance and reliabilityof a chemical propulsion engine.The underlying processes include liquid atomization,evaporation,mixing,and chemical reactions.This paper presents a high-fidelity numerical study of liquidatomization and spray combustion under high-pressure conditions,emphasizing the effects of pres-sure oscillations on the flow evolution and combustion dynamics.The theoretical framework isbased on the three-dimensional conservation equations for multiphase flows and turbulent combus-tion.The numerical solution is achieved using a coupling method of volume-of-fluid and Lagran-gian particle tracking.The Zhuang-Kadota-Sutton(ZKS)high-pressure evaporation model andthe eddy breakup-Arrhenius combustion model are employed.Simulations are conducted for amodel combustion chamber with impinging-jet injectors using liquid oxygen and kerosene as pro-pellants.Both conditions with and without inlet and outlet pressure oscillations are considered.Thefindings reveal that pressure oscillations amplify flow fluctuations and can be characterized usingkey physical parameters such as droplet evaporation,chemical reaction,and chamber pressure.The spectral analysis uncovers the axial variations of the dominant and secondary frequenciesand their amplitudes in terms of the characteristic physical quantities.This research helps establisha methodology for exploring the coupling effect of liquid atomization and spray combustion.It alsoprovides practical insights into their responses to pressure oscillations during the occurrence ofcombustion instability.This information can be used to enhance the design and operation ofliquid-fueled propulsion engines.展开更多
Objective:This study aimed to determine the effect of a culture-specificbehavior modificationprogram on glycated hemoglobin(HbA1c)and blood pressure among adults with diabetes and hypertension.Methods:This study was a...Objective:This study aimed to determine the effect of a culture-specificbehavior modificationprogram on glycated hemoglobin(HbA1c)and blood pressure among adults with diabetes and hypertension.Methods:This study was a single-blind randomized controlled trial design.From January to May 2024,a total of 60 patients with uncontrolled type 2 diabetes and hypertension from the primary care unit of a hospital in northeastern(Isan)Thailand were recruited.The intervention group received the usual care supplemented by a culture-specificbehavior modificationprogramm implemented through interactive classes and online web application consisting of information,motivation,and behavioral skills(diet,exercise,and medication use),the control group received the usual care.HbA1c and blood pressure measurements were collected at both baseline and at 12 weeks.Results:A total of 51 patients completed the study,the intervention group(n=26)and control group(n=25),respectively.After 12 weeks,23.1%of patients in the intervention group could maintain their HbA1c<7.0%;those with poorly controlled HbA1c decreased from 7.7%at baseline to 3.8%at 12 weeks.After 12 weeks,69.2%of intervention group participants could maintain systolic blood pressure<130 mmHg and 53.8%could keep diastolic blood pressure<80 mmHg.Analysis revealed that HbA1c,systolic and diastolic blood pressure levels in the intervention group were lower than the control group after the intervention(P<0.05).There was a statistically significantdifference a linear combination of HbA1c and blood pressure(systolic and diastolic BP levels)between time and group(P<0.05).Conclusion:These results suggest that healthcare providers can incorporate elements of this program to manage blood glucose and blood pressure effectively.Future studies should consider a longitudinal design with a larger sample size and include outcomes of lipid levels to confirmlong-term motivation.展开更多
The pressure and temperature increase resulting from the impact of different threats onto target materials is analyzed with a unified laboratory-scale setup.This allows deriving qualitative information on the occurrin...The pressure and temperature increase resulting from the impact of different threats onto target materials is analyzed with a unified laboratory-scale setup.This allows deriving qualitative information on the occurring phenomenology as well as quantitative statements about the relative effects sizes as a function of target material and threat.The considered target materials are steel,aluminum,and magnesium.As threats,kinetic energy penetrator,explosively formed projectile,and shaped charge jet are used.For the investigated combinations,the measured overpressures vary by a factor of up to 5 for a variation of the material,by a factor of up to 7 for a variation of the threat,and by a factor larger than 15for a simultaneous variation of both.The obtained results as well as the experimental approach are relevant for the basic understanding of impact effects and risks due to material reactivity.The paper combines two main aims.Firstly,to provide a summary of own prior work in a coherent journal article and,secondly,to review and discuss these earlier results with a new perspective.展开更多
Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings.Previous narrow backfill earth pressure studies have neglected seismic-unsatur...Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings.Previous narrow backfill earth pressure studies have neglected seismic-unsaturated seepage multi-field coupling,resulting in inaccurate estimates.To address these deficiencies,this paper proposed a calculation method for seismic passive earth pressure in unsaturated narrow backfill,based on inclined thin-layer units.It considers the interlayer shear stress,arching effect,and the multi-field coupling of seismic-unsaturated seepage.Additionally,this paper includes a parametric sensitivity analysis.The outcomes indicate that the earthquake passive ground pressure of unsaturated narrow backfill can be reduced by increasing the aspect ratio,seismic acceleration coefficient,and unsaturation parameterα.It can also be reduced by decreasing the effective interior friction angle,soil cohesion,wallearth friction angle,and vertical discharge.Furthermore,for any width soil,lowering the elevation of the action point of passive thrust can be attained by raising the effective interior friction angle,wall-earth friction angle,and unsaturation parameterα.Reducing soil cohesion,seismic acceleration coefficient,and vertical discharge can also lower the height of the application point of passive thrust.展开更多
Background: Tooth loss results in impaired mastication, which in turn, makes it difficult to chew hard food, consequently leading to deteriorate dietary habits and to develop hypertension. The purpose of this study wa...Background: Tooth loss results in impaired mastication, which in turn, makes it difficult to chew hard food, consequently leading to deteriorate dietary habits and to develop hypertension. The purpose of this study was to examine the effect of tooth loss on blood pressure among Congolese population. Methods: A cross-sectional study was conducted from October 2019 until December 2023 among Congolese population aged at least 30 years reporting to the living in DR Congo. All participants were enrolled from Dental Clinic located in the DR Congo. To be eligible to participate in the study, were the willing to participate and having signed informed consent;had a missing tooth;had carried out blood pressure measurement (hypertension/normotensive). The exclusion criteria were determined: being less than 30 years old, being pregnant for women considering the risk of existing gestational hypertension, obesity, excessive alcohol consumption, smoking, and diabetes. Hypertension was defined as the mean of three measurements of systolic blood pressure (SBP) (140 mmHg or higher), diastolic blood pressure (DBP) (90 mm or higher) or physician diagnosed hypertension confirmed from medical records. We determined the number of tooth loss from oral examination. A multivariable logistic regression model was used to investigate the effect of tooth loss on blood pressure. Results: In all, 25,396 participants were enrolled among Congolese population for this study. After oral examination, 13,421 were excluded for no tooth loss and 11,975 participants were selected. The average number of tooth loss among study population was 11.06. Among the participants with hypertension had lost an average of 11 teeth, significantly higher than those without hypertension (6.09) (p = 0.001). After adjusting for covariates (socio-demographic characteristics), tooth loss (>10) was significantly associated with hypertension, with OR = 1.32 (95% CI 1.073 - 2.38). Conclusion: Tooth loss maybe associated with severe hypertension among Congolese population adults. Prevention of tooth loss is very important to the overall health of this population.展开更多
Objective: This study aims to investigate the drainage effect and clinical outcomes of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery, comparing the differences in postoperativ...Objective: This study aims to investigate the drainage effect and clinical outcomes of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery, comparing the differences in postoperative pain, hospital stay, and other factors between the negative pressure group and the control group. Methods: This study is a prospective controlled trial that selected patients undergoing two-port thoracoscopic valve surgery at a certain hospital from January 2019 to December 2024. Patients were randomly assigned to the control group and the negative pressure group using a random number table method. The control group consisted of 30 patients (20 males, 10 females, mean age 42.03 ± 12.89 years), and the negative pressure group consisted of 35 patients (26 males, 9 females, mean age 41.84 ± 11.83 years). The control group received traditional chest drainage, while the negative pressure group received negative pressure chest drainage. Postoperative pain scores, hospital stay, drainage time, number of tube blockages, and incidences of pneumothorax or subcutaneous emphysema were recorded and statistically analyzed. Results: The negative pressure group had a significantly shorter postoperative drainage time compared to the control group (49.09 ± 11.99 hours vs. 79.10 ± 7.32 hours, P < 0.001). The postoperative pain score was lower in the negative pressure group (4.49 ± 1.27 vs. 7.03 ± 0.85, P < 0.001), and the hospital stay was significantly shorter (9.83 ± 1.69 days vs. 14.73 ± 2.32 days, P < 0.001). The incidence of pneumothorax or subcutaneous emphysema was significantly lower in the negative pressure group than in the control group (14.29% vs. 56.67%, P = 0.0003). Conclusion: The application of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery can effectively reduce postoperative pain, shorten hospital stay, and lower the incidence of tube blockage and pneumothorax, demonstrating good clinical outcomes.展开更多
BiCuSeO thermoelectric ceramics were fabricated using self-propagating high-temperature synthesis(SHS)combined with spark plasma sintering(SPS),and their phase compositions,microstructure,electrical properties,and the...BiCuSeO thermoelectric ceramics were fabricated using self-propagating high-temperature synthesis(SHS)combined with spark plasma sintering(SPS),and their phase compositions,microstructure,electrical properties,and thermal properties were systematically characterized and analyzed.The experimental results demonstrate that applying high-pressure condition during the sintering process will effectively restrict grain growth,reduce porosity,and lead to an increase in electrical conductivity.Simultaneously,high pressure sintering conditions reduce grain size and introduce additional grain boundaries and defects,which strengthens phonon scattering,thereby further decreasing both lattice thermal conductivity and total thermal conductivity.As a result,the high-pressure conditions significantly improve the thermoelectric figure of merit(ZT)of BiCuSeO.In brief,the samples sintered at 600℃under 200 MPa achieve a maximum ZT value of 0.64 at approximately 792 K.展开更多
Stimuli-responsive polymers capable of rapidly altering their chain conformation in response to external stimuli exhibit broad applica-tion prospects.Experiments have shown that pressure plays a pivotal role in regula...Stimuli-responsive polymers capable of rapidly altering their chain conformation in response to external stimuli exhibit broad applica-tion prospects.Experiments have shown that pressure plays a pivotal role in regulating the microscopic chain conformation of polymers in mixed solvents,and one notable finding is that increasing the pressure can lead to the vanishing of the co-nonsolvency effect.However,the mecha-nisms underlying this phenomenon remain unclear.In this study,we systematically investigated the influence of pressure on the co-nonsolvency effect of single-chain and multi-chain homopolymers in binary mixed good-solvent systems using molecular dynamics simulations.Our results show that the co-nonsolvency-induced chain conformation transition and aggregation behavior significantly depend on pressure in allsingle-chain and multi-chain systems.In single-chain systems,at low pressures,the polymer chain maintains a collapsed state over a wide range of co-solvent fractions(x-range)owing to the co-nonsolvency effect.As the pressure increases,the x-range of the collapsed state gradually narrows,ac-companied by a progressive expansion of the chain.In multichain systems,polymer chains assemble into approximately spherical aggregates over a broad x-range at low pressures owing to the co-nonsolvency effect.Increasing the pressure reduces the x-range for forming aggregates and leads to the formation of loose aggregates or even to a state of dispersed chains at some x-range.These findings indicate that increasing the pressure can weaken or even offset the co-nonsolvency effect in some x-range,which is in good agreement with the experimental observations.Quantitative analysis of the radial density distributions and radial distribution functions reveals that,with increasing pressure,(1)the densities of both polymers and co-solvent molecules within aggregates decrease,while that of the solvent molecule increases;and(2)the effective interac-tions between the polymer and the co-solvent weaken,whereas those between the polymer and solvent strengthen.This enhances the incorpo-ration of solvent molecules within the chains,thereby weakening or even suppressing the chain aggregation.Our study not only elucidates the regulatory mechanism of pressure on the microscopic chain conformations and aggregation behaviors of polymers,but also may provide theo-retical guidance for designing smart polymericmaterials based on mixed solvents.展开更多
Understanding the effects of temperature on the hydro-mechanical behavior of compacted bentonite is important for performance assessments of bentonitebased buffer,backfill,and sealing systems in deep geological dispos...Understanding the effects of temperature on the hydro-mechanical behavior of compacted bentonite is important for performance assessments of bentonitebased buffer,backfill,and sealing systems in deep geological disposal of high-level radioactive wastes.Motivated by such applications,most past experimental studies were focused on highly compacted and high-quality bentonite.Such degrees of dry densities may not be economically or technically feasible for other emerging applications,including as an alternative material to cement in plugging and abandonment of wells.A bespoke high-pressure high-temperature constant rate of strain(CRS)apparatus was developed for the work reported here to conduct a series of tests for evaluating the hydro-mechanical response of compacted bentonite to elevated temperatures.Experiments were performed with bentonite specimens with high impurity contents at a range of dry densities(1.1,1.4,and 1.7 Mg/m^(3))and temperatures between 20 and 80℃.The results show that temperature increase leads to the decrease of swelling pressure for all studied densities.Larger reductions of swelling pressure were observed with increasing dry densities,suggesting the possibility of a larger exchange of pore water in the microstructure system of the clay.The transfer of water from micropores to macropores at elevated temperatures is shown to be a key controlling process at high-density compacted bentonite by which temperature affects the swelling pressure and hydraulic conductivity.展开更多
The Casimir pressure plays an important role in the adhesion stability of nanofilms at submicro scales.In this work,the Casimir pressure of peptide films deposited on a layered substrate is investigated.Three types of...The Casimir pressure plays an important role in the adhesion stability of nanofilms at submicro scales.In this work,the Casimir pressure of peptide films deposited on a layered substrate is investigated.Three types of semi-infinite substrates,i.e.,silica,silicon and gold,are considered.The buffer layer between the peptide film and substrate consists of silicon or silica.The switching sign of the Casimir pressure can be controlled in a region ranging from about 130 nm to 1000 nm,depending on the thickness of the buffer layer and the substrate.The results suggest that the critical thickness of peptide films for Casimir equilibrium increases(or decreases)by increasing the thickness of the silicon(or silica)buffer film.The influences of wetting and electrolyte screening on the Casimir pressure are also investigated.Our finding provides a theoretical guide for the adhesion stability of peptide films in organic electronics.展开更多
The mechanical properties,microstructure and second phase precipitation behavior of flange forgings for high-pressure hydrogen storage vessels at different tempering temperatures(620–700℃)were studied.The results sh...The mechanical properties,microstructure and second phase precipitation behavior of flange forgings for high-pressure hydrogen storage vessels at different tempering temperatures(620–700℃)were studied.The results showed that when tempered at 620–680°C,the main microstructure of the test steel was tempered sorbite,and the main microstructure of tempered steel changed to martensite at 700℃.At 700℃,the dislocation density increased and some retained austenite existed.With the tempering temperature increasing,the yield strength showed a decreasing trend,the formation of fresh martensite made the tensile strength first decrease and then increase slightly,the impact energy at−40℃increased first and then decreased,and the impact energy at 660℃had the maximum value.The precipitates of MC type were mainly(Mo,V,Ti)C.The test steel had excellent strength and toughness matching at 660℃tempering,the tensile strength at different cross section locations was above 750 MPa,the impact energy was above 200 J at−40℃,and the relative percentage reduction of area(ZH2/ZN2)was above 75%at hydrogen environment of 6.3 MPa.展开更多
Background:In the field of organizational behavior,various aspects that have an impact on employee well-being gradually become a focus of attention.Among them,performance pressure,which is a component of workplace str...Background:In the field of organizational behavior,various aspects that have an impact on employee well-being gradually become a focus of attention.Among them,performance pressure,which is a component of workplace stressors that has a great influence on employees’job performance as well as well-being,has been little studied.Therefore,this paper constructs a research model,which uses workplace anxiety as a mediating variable and vocational delay of gratification as a moderating variable,to explore the impact of performance pressure on employee well-being.Methods:Reliable data were collected by questionnaire method and data analysis was conducted with the help of SPSS 26.0.In this paper,the data statistics are carried out by correlation analysis,mediation effect analysis,and moderating effect analysis,and the regression analysis is further studied.Results:The finding shows that performance pressure impacts employee well-being negatively,and workplace anxiety has a significant negative impact on employee well-being.When the workplace anxiety variable is added,the negative impact of performance pressure on employee well-being is still significant.Therefore,it can be verified that workplace anxiety plays an intermediary role in the influencing mechanism of performance pressure on employee well-being.While high vocational delay satisfaction weakens the influence of performance pressure on employee well-being.It’s interesting that under the adjustment of low delayed gratification,low-performance pressure will lead to higher employee well-being,and the organization’s conscious reduction of performance pressure is conducive to improving employeewell-being,and under the adjustment of high delayed gratification,low-performance pressure leads to higher employee well-being,and high-performance pressure leads to lower employee well-being,which shows the weakening effect of high delayed gratification,that means vocational delay gratification plays a negative regulating role in the influencing mechanism of performance pressure and employee well-being.Conclusion:Under the mediating role of workplace anxiety,performance pressure has a significant negative impact on employee well-being,and in this influence mechanism,vocational delay gratification plays a significant negative moderating role.展开更多
Dielectric barrier discharges(DBDs)are primarily utilized as efficient sources of large-volume diffuse plasmas.However,the synergistic interaction of certain key plasma factors limits their broader application.In the ...Dielectric barrier discharges(DBDs)are primarily utilized as efficient sources of large-volume diffuse plasmas.However,the synergistic interaction of certain key plasma factors limits their broader application.In the present paper,we report numerical investigations of the effects of voltage amplitude in dual-frequency excitation on atmospheric DBDs using a 50 kHz/5 MHz frequency combination.Our results indicate that varying the voltages for low frequency(LF)and radio frequency(RF)significantly influences the electron dynamics during discharge,resulting in distinct spatio-temporal distributions of electron and metastable particle densities.These findings contribute to the regulation of discharges under atmospheric pressure conditions and facilitate the attainment of non-equilibrium and nonlinear plasma parameters.展开更多
Using natural gas(NG)as the primary fuel helps alleviate the fossil fuel crisis while reducing engine soot and nitrogen oxide(NO_(X))emissions.In this paper,the influences of a novel split injection concept on an NG h...Using natural gas(NG)as the primary fuel helps alleviate the fossil fuel crisis while reducing engine soot and nitrogen oxide(NO_(X))emissions.In this paper,the influences of a novel split injection concept on an NG high pressure direct injection(HPDI)engine are examined.Four typical split injection strategies,namely split pre-injection of pilot diesel(PD)and NG,split post-injection of PD and NG,split pre-injection of NG,and split post-injection of PD,were developed to investigate the influences on combustion and emissions.Results revealed that split pre injection of NG enhanced the atomization of PD,whereas the split post-injection of NG lowered the temperature in the core region of the PD spray,resulting in the deterioration of combustion.The effect of the split injection strategy on indicated thermal efficiency exceeded 7.5%.Split pre-injection was favorable to enhancing thermal efficiency,whereas split post-injection was not.Ignition delay,combustion duration,and premixed combustion time proportion were affected by injection strategies by 3.8%,50%,and 19.7%,respectively.Split pre-injection increased CH_(4) emission in the exhaust.Split post-injection,especially split post-injection of PD and NG,reduced the unburned CH_(4) emission by approximately 30%.When the split post-injection ratio was less than 30%,the trade-off between NO_(X) and soot was interrupted.The distribution range of hydroxyl radicals was expanded by pre-injection,and NO_(X) was generated in the region where the NG jet hit the wall.This paper provides valuable insights into the optimization of HPDI injection parameters.展开更多
Lithium plating is a detrimental phenomenon in lithium-ion cells that compromises both functionality and safety.This study investigates electro-chemo-mechanical behaviors of lithium plating in lithium iron phosphate p...Lithium plating is a detrimental phenomenon in lithium-ion cells that compromises both functionality and safety.This study investigates electro-chemo-mechanical behaviors of lithium plating in lithium iron phosphate pouch cells under different external pressures.Atomic force microscopy nanoindentation is performed on the graphite electrode to analyze the influence of external pressure on solid-electrolyte interphase(SEI),revealing that the mechanical strength of SEI,indicated by Young's modulus,increases with the presence of external pressure.Then,an improved phase field model for lithium plating is developed by incorporating electrochemical parameterization based on nonequilibrium thermodynamics.The results demonstrate that higher pressure promotes lateral lithium deposition,covering a larger area of SEI.Moreover,electrochemical impedance spectroscopy and thickness measurements of the pouch cells are conducted during overcharge,showing that external pressure suppresses gas generation and thus increases the proportion of lithium deposition among galvanostatic overcharge reactions.By integrating experimental results with numerical simulations,it is demonstrated that moderate pressure mitigates SEI damage during lithium plating,while both insufficient and excessive pressure may exacerbate it.This study offers new insights into optimizing the design and operation of lithium iron phosphate pouch cells under external pressures.展开更多
The deteriorated bearing capacity and nonlinear expansion deformation of weakly cemented Xiyu conglomerate under complex water environments and stress disturbances pose significant risks to the safety of stratum engin...The deteriorated bearing capacity and nonlinear expansion deformation of weakly cemented Xiyu conglomerate under complex water environments and stress disturbances pose significant risks to the safety of stratum engineering construction.In this study,to precisely comprehend the influences of pore pressure(P_(w))and stress path on the deformation characteristics,dilation behavior,and damage evolution of Xiyu conglomerate,a series of triaxial monotonic loading and cyclic loading-unloading tests were conducted on saturated Xiyu conglomerate with varied confining pressures(σ_(3))and pore pressures.The results indicate that as P_(w)increases,the secant modulus,unloading modulus,and loading modulus decrease,but increase with risingσ_(3).Additionally,P_(w)accelerates the onset of dilatancy,whereasσ_(3)delays it.Asσ_(3)increases,the peak stress,crack damage stress,and residual strength increase,while these parameters decrease with increasing P_(w).A positive correlation exists between the effective confining pressure and the effective axial stress.Furthermore,an increase in P_(w)results in a greater maximum dilation angle,which decreases with increasingσ_(3).The failure mode is mainly a tensile-shear mixed failure mode.The high pore pressure and cyclic loading stress path aggravate the deterioration of strength and failure mode of the weakly cemented Xiyu conglomerate.Finally,a new damage variable and conceptual model are proposed and discussed.The findings provide insight into the damage and failure mechanism of the Xiyu conglomerate under pore pressure and cyclic disturbance,offering a crucial experimental foundation for the design and construction of hydropower projects in the Xiyu conglomerate layer.展开更多
Coal dust explosions are severe safety accidents in coal mine production,posing significant threats to life and property.Predicting the maximum explosion pressure(Pm)of coal dust using deep learning models can effecti...Coal dust explosions are severe safety accidents in coal mine production,posing significant threats to life and property.Predicting the maximum explosion pressure(Pm)of coal dust using deep learning models can effectively assess potential risks and provide a scientific basis for preventing coal dust explosions.In this study,a 20-L explosion sphere apparatus was used to test the maximum explosion pressure of coal dust under seven different particle sizes and ten mass concentrations(Cdust),resulting in a dataset of 70 experimental groups.Through Spearman correlation analysis and random forest feature selection methods,particle size(D_(10),D_(20),D_(50))and mass concentration(Cdust)were identified as critical feature parameters from the ten initial parameters of the coal dust samples.Based on this,a hybrid Long Short-Term Memory(LSTM)network model incorporating a Multi-Head Attention Mechanism and the Sparrow Search Algorithm(SSA)was proposed to predict the maximum explosion pressure of coal dust.The results demonstrate that the SSA-LSTM-Multi-Head Attention model excels in predicting the maximum explosion pressure of coal dust.The four evaluation metrics indicate that the model achieved a coefficient of determination(R^(2)),root mean square error(RMSE),mean absolute percentage error(MAPE),and mean absolute error(MAE)of 0.9841,0.0030,0.0074,and 0.0049,respectively,in the training set.In the testing set,these values were 0.9743,0.0087,0.0108,and 0.0069,respectively.Compared to artificial neural networks(ANN),random forest(RF),support vector machines(SVM),particle swarm optimized-SVM(PSO-SVM)neural networks,and the traditional single-model LSTM,the SSA-LSTM-Multi-Head Attention model demonstrated superior generalization capability and prediction accuracy.The findings of this study not only advance the application of deep learning in coal dust explosion prediction but also provide robust technical support for the prevention and risk assessment of coal dust explosions.展开更多
Objective To investigate the effects of moxibustion on wound healing and evaluate whether the efficacy of moxibustion at different temperatures varies.Additionally,to explore the mechanism by which moxibustion regulat...Objective To investigate the effects of moxibustion on wound healing and evaluate whether the efficacy of moxibustion at different temperatures varies.Additionally,to explore the mechanism by which moxibustion regulates the phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/mammalian rapamycin target protein(mTOR)signaling pathway on wound healing and cell apoptosis.Methods A total of 90 SPF-grade SD rats were randomly divided into six groups(15 rats per group):control group,model group,recombinant bovine basic fibroblast growth factor gel(rb-bFGF)group,moxibustion group A[temperature(42±1)℃],moxibustion group B[temperature(45±1)℃],and moxibustion group C[temperature(48±1)℃].Except the control group,the interventions were conducted in the other groups with pressure ulcer induced by ischemia/reperfusion injury.In the control group,povidone-iodine was administered at the knee joint.In the model group,after povidone-iodine applied at the pressure ulcer,petroleum jelly gauze was bandaged.In the rb-bFGF group,after povidone-iodine applied at the pressure ulcer,rb-bFGF was smeared and petroleum jelly gauze was bandaged.In the moxibustion group A,the suspending moxibustion with moxa stick was delivered 3 cm to 5 cm above the ulcer.The paperless temperature recorder probe was placed on the wound surface where moxibustion was delivered,and the real-time temperature was monitored and adjusted,kept at(42±1)℃.The moxibustion temperature was kept at(45±1)℃ in the moxibustion group B,and(48±1)℃ in the moxibustion group C.The intervention lasted 14 days in each group.The wound healing rates were compared on the 3,5,7 and 14 days after the first intervention among the 6 groups.After 14-day intervention respectively,the histopathological changes were observed with HE staining,apoptosis was detected with TUNEL method and flow cytometry;VEGF-A protein expression determined with immunohistochemistry;the contents of Interleukin-6(IL-6),tumor necrosis factor-α(TNF-α)and transforming growth factor-β(TGF-β)in serum with ELISA,and PI3K/AKT/mTOR related protein and mRNA expression was with Western blotting and qRT-PCR in wound tissues of each group.Results Regarding the intervention effects,(1)compared with the control group,the model group showed significant inflammatory infiltration in wound tissues,higher levels of cell apoptosis,and elevated serum levels of IL-6,TNF-αand TGF-β(P<0.05);(2)compared with the model group,the rb-bFGF group and 3 moxibustion groups showed higher wound healing rates(P<0.05),reduced inflammatory infiltration in the wound tissues,lower levels of cell apoptosis,and decreased serum levels of IL-6,TNF-αand TGF-β(P<0.05).Among the moxibustion groups,group C showed significantly better results than group A(P<0.01).Regarding the mechanism,(1)compared with the control group,the model group exhibited significantly higher protein and mRNA expression levels of PI3K/AKT/mTOR signal pathway components(P<0.05);(2)compared with the model group,the rb-bFGF group and 3 moxibustion groups showed lower protein and mRNA expression levels of PI3K/AKT/mTOR signal pathway components(P<0.05).Among the moxibustion groups,group C showed significantly higher expression levels than group A(P<0.01).Conclusion Moxibustion significantly promotes wound healing,with high-temperature moxibustion being more effective than low-temperature moxibustion in reducing the expression of inflammatory factors and cell apoptosis,thereby improving wound healing rates.It is presented that the higher moxibustion temperature,the higher wound healing rate,which may be associated with the regulation of PI3K/AKT/mTOR signal pathway with moxibustion.展开更多
Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects...Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.展开更多
基金supported by the National Key R&D Program of China(Grant No.2023YFA1406200)the National Natural Science Foundation of China(No.12274177 and 12304261)the China Postdoctoral Science Foundation(No.2024M751076)。
文摘Luminescent metal-organic frameworks(MOFs)have garnered significant attention due to their structural tunability and potential applications in solid-state lighting,bioimaging,sensing,anticounterfeiting,and other fields.Nevertheless,due to the tendency of1,4-benzenedicarboxylic acid(BDC)to rotate within the framework,MOFs composed of it exhibit significant non-radiative energy dissipation and thus impair the emissive properties.In this study,efficient luminescence of MIL-140A nanocrystals(NCs)with BDC rotors as ligands is achieved by pressure treatment strategy.Pressure treatment effectively modulates the pore structure of the framework,enhancing the interactions between the N,N-dimethylformamide vip molecules and the BDC ligands.The enhanced host-vip interaction contributes to the structural rigidity of the MOF,thereby suppressing the rotation-induced excited-state energy loss.As a result,the pressure-treated MIL-140A NCs displayed bright blue-light emission,with the photoluminescence quantum yield increasing from an initial 6.8%to 69.2%.This study developed an effective strategy to improve the luminescence performance of rotor ligand MOFs,offers a new avenue for the rational design and synthesis of MOFs with superior luminescent properties.
基金supported by the National Natural Science Foundation of China(Nos.U23B6009 and 12272050)。
文摘Combustion dynamics are a critical factor in determining the performance and reliabilityof a chemical propulsion engine.The underlying processes include liquid atomization,evaporation,mixing,and chemical reactions.This paper presents a high-fidelity numerical study of liquidatomization and spray combustion under high-pressure conditions,emphasizing the effects of pres-sure oscillations on the flow evolution and combustion dynamics.The theoretical framework isbased on the three-dimensional conservation equations for multiphase flows and turbulent combus-tion.The numerical solution is achieved using a coupling method of volume-of-fluid and Lagran-gian particle tracking.The Zhuang-Kadota-Sutton(ZKS)high-pressure evaporation model andthe eddy breakup-Arrhenius combustion model are employed.Simulations are conducted for amodel combustion chamber with impinging-jet injectors using liquid oxygen and kerosene as pro-pellants.Both conditions with and without inlet and outlet pressure oscillations are considered.Thefindings reveal that pressure oscillations amplify flow fluctuations and can be characterized usingkey physical parameters such as droplet evaporation,chemical reaction,and chamber pressure.The spectral analysis uncovers the axial variations of the dominant and secondary frequenciesand their amplitudes in terms of the characteristic physical quantities.This research helps establisha methodology for exploring the coupling effect of liquid atomization and spray combustion.It alsoprovides practical insights into their responses to pressure oscillations during the occurrence ofcombustion instability.This information can be used to enhance the design and operation ofliquid-fueled propulsion engines.
基金supported by the 90th Anniversary of Chulalong-korn University Scholarship(Ratchadaphiseksomphot Endowment Fund)。
文摘Objective:This study aimed to determine the effect of a culture-specificbehavior modificationprogram on glycated hemoglobin(HbA1c)and blood pressure among adults with diabetes and hypertension.Methods:This study was a single-blind randomized controlled trial design.From January to May 2024,a total of 60 patients with uncontrolled type 2 diabetes and hypertension from the primary care unit of a hospital in northeastern(Isan)Thailand were recruited.The intervention group received the usual care supplemented by a culture-specificbehavior modificationprogramm implemented through interactive classes and online web application consisting of information,motivation,and behavioral skills(diet,exercise,and medication use),the control group received the usual care.HbA1c and blood pressure measurements were collected at both baseline and at 12 weeks.Results:A total of 51 patients completed the study,the intervention group(n=26)and control group(n=25),respectively.After 12 weeks,23.1%of patients in the intervention group could maintain their HbA1c<7.0%;those with poorly controlled HbA1c decreased from 7.7%at baseline to 3.8%at 12 weeks.After 12 weeks,69.2%of intervention group participants could maintain systolic blood pressure<130 mmHg and 53.8%could keep diastolic blood pressure<80 mmHg.Analysis revealed that HbA1c,systolic and diastolic blood pressure levels in the intervention group were lower than the control group after the intervention(P<0.05).There was a statistically significantdifference a linear combination of HbA1c and blood pressure(systolic and diastolic BP levels)between time and group(P<0.05).Conclusion:These results suggest that healthcare providers can incorporate elements of this program to manage blood glucose and blood pressure effectively.Future studies should consider a longitudinal design with a larger sample size and include outcomes of lipid levels to confirmlong-term motivation.
文摘The pressure and temperature increase resulting from the impact of different threats onto target materials is analyzed with a unified laboratory-scale setup.This allows deriving qualitative information on the occurring phenomenology as well as quantitative statements about the relative effects sizes as a function of target material and threat.The considered target materials are steel,aluminum,and magnesium.As threats,kinetic energy penetrator,explosively formed projectile,and shaped charge jet are used.For the investigated combinations,the measured overpressures vary by a factor of up to 5 for a variation of the material,by a factor of up to 7 for a variation of the threat,and by a factor larger than 15for a simultaneous variation of both.The obtained results as well as the experimental approach are relevant for the basic understanding of impact effects and risks due to material reactivity.The paper combines two main aims.Firstly,to provide a summary of own prior work in a coherent journal article and,secondly,to review and discuss these earlier results with a new perspective.
基金Project(42277175)supported by the National Natural Science Foundation of ChinaProject(NRMSSHR-2022-Z08)supported by the Key Laboratory of Natural Resources Monitoring and Supervision in Southern Hilly Region,Ministry of Natural Resources,China。
文摘Narrow backfill earth pressure estimation is applied to study the stability of supporting structures in the vicinity of existing buildings.Previous narrow backfill earth pressure studies have neglected seismic-unsaturated seepage multi-field coupling,resulting in inaccurate estimates.To address these deficiencies,this paper proposed a calculation method for seismic passive earth pressure in unsaturated narrow backfill,based on inclined thin-layer units.It considers the interlayer shear stress,arching effect,and the multi-field coupling of seismic-unsaturated seepage.Additionally,this paper includes a parametric sensitivity analysis.The outcomes indicate that the earthquake passive ground pressure of unsaturated narrow backfill can be reduced by increasing the aspect ratio,seismic acceleration coefficient,and unsaturation parameterα.It can also be reduced by decreasing the effective interior friction angle,soil cohesion,wallearth friction angle,and vertical discharge.Furthermore,for any width soil,lowering the elevation of the action point of passive thrust can be attained by raising the effective interior friction angle,wall-earth friction angle,and unsaturation parameterα.Reducing soil cohesion,seismic acceleration coefficient,and vertical discharge can also lower the height of the application point of passive thrust.
文摘Background: Tooth loss results in impaired mastication, which in turn, makes it difficult to chew hard food, consequently leading to deteriorate dietary habits and to develop hypertension. The purpose of this study was to examine the effect of tooth loss on blood pressure among Congolese population. Methods: A cross-sectional study was conducted from October 2019 until December 2023 among Congolese population aged at least 30 years reporting to the living in DR Congo. All participants were enrolled from Dental Clinic located in the DR Congo. To be eligible to participate in the study, were the willing to participate and having signed informed consent;had a missing tooth;had carried out blood pressure measurement (hypertension/normotensive). The exclusion criteria were determined: being less than 30 years old, being pregnant for women considering the risk of existing gestational hypertension, obesity, excessive alcohol consumption, smoking, and diabetes. Hypertension was defined as the mean of three measurements of systolic blood pressure (SBP) (140 mmHg or higher), diastolic blood pressure (DBP) (90 mm or higher) or physician diagnosed hypertension confirmed from medical records. We determined the number of tooth loss from oral examination. A multivariable logistic regression model was used to investigate the effect of tooth loss on blood pressure. Results: In all, 25,396 participants were enrolled among Congolese population for this study. After oral examination, 13,421 were excluded for no tooth loss and 11,975 participants were selected. The average number of tooth loss among study population was 11.06. Among the participants with hypertension had lost an average of 11 teeth, significantly higher than those without hypertension (6.09) (p = 0.001). After adjusting for covariates (socio-demographic characteristics), tooth loss (>10) was significantly associated with hypertension, with OR = 1.32 (95% CI 1.073 - 2.38). Conclusion: Tooth loss maybe associated with severe hypertension among Congolese population adults. Prevention of tooth loss is very important to the overall health of this population.
文摘Objective: This study aims to investigate the drainage effect and clinical outcomes of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery, comparing the differences in postoperative pain, hospital stay, and other factors between the negative pressure group and the control group. Methods: This study is a prospective controlled trial that selected patients undergoing two-port thoracoscopic valve surgery at a certain hospital from January 2019 to December 2024. Patients were randomly assigned to the control group and the negative pressure group using a random number table method. The control group consisted of 30 patients (20 males, 10 females, mean age 42.03 ± 12.89 years), and the negative pressure group consisted of 35 patients (26 males, 9 females, mean age 41.84 ± 11.83 years). The control group received traditional chest drainage, while the negative pressure group received negative pressure chest drainage. Postoperative pain scores, hospital stay, drainage time, number of tube blockages, and incidences of pneumothorax or subcutaneous emphysema were recorded and statistically analyzed. Results: The negative pressure group had a significantly shorter postoperative drainage time compared to the control group (49.09 ± 11.99 hours vs. 79.10 ± 7.32 hours, P < 0.001). The postoperative pain score was lower in the negative pressure group (4.49 ± 1.27 vs. 7.03 ± 0.85, P < 0.001), and the hospital stay was significantly shorter (9.83 ± 1.69 days vs. 14.73 ± 2.32 days, P < 0.001). The incidence of pneumothorax or subcutaneous emphysema was significantly lower in the negative pressure group than in the control group (14.29% vs. 56.67%, P = 0.0003). Conclusion: The application of negative pressure chest drainage in patients after two-port thoracoscopic valve surgery can effectively reduce postoperative pain, shorten hospital stay, and lower the incidence of tube blockage and pneumothorax, demonstrating good clinical outcomes.
基金Funded by the National Natural Science Foundation of China(Nos.52322207 and 52202289)the National Key Research and Development Plan of China(No.2021YFB3701400)+2 种基金the Independent Innovation Projects of the Hubei Longzhong Laboratory(No.2022ZZ-11)Funded by the National Natural Science Foundation of China(Nos.52322207 and 52202289)the National Key Research and Development Plan of China(No.2021YFB3701400)the Independent Innovation Projects of the Hubei Longzhong Laboratory(No.2022ZZ-11)。
文摘BiCuSeO thermoelectric ceramics were fabricated using self-propagating high-temperature synthesis(SHS)combined with spark plasma sintering(SPS),and their phase compositions,microstructure,electrical properties,and thermal properties were systematically characterized and analyzed.The experimental results demonstrate that applying high-pressure condition during the sintering process will effectively restrict grain growth,reduce porosity,and lead to an increase in electrical conductivity.Simultaneously,high pressure sintering conditions reduce grain size and introduce additional grain boundaries and defects,which strengthens phonon scattering,thereby further decreasing both lattice thermal conductivity and total thermal conductivity.As a result,the high-pressure conditions significantly improve the thermoelectric figure of merit(ZT)of BiCuSeO.In brief,the samples sintered at 600℃under 200 MPa achieve a maximum ZT value of 0.64 at approximately 792 K.
基金support provided by the National Natural Science Foundation of China(Nos.22173051,21829301,21774066),PCSIRT(IRT1257)the College Discipline Innovation and Intelligence Introduction Program(111 Project(B16027)+2 种基金the International Cooperation Base(No.2016D01025)Tianjin International Joint Research and Development Center)P.Zhang acknowledges the financial support provided by NSFC(No.22473024).
文摘Stimuli-responsive polymers capable of rapidly altering their chain conformation in response to external stimuli exhibit broad applica-tion prospects.Experiments have shown that pressure plays a pivotal role in regulating the microscopic chain conformation of polymers in mixed solvents,and one notable finding is that increasing the pressure can lead to the vanishing of the co-nonsolvency effect.However,the mecha-nisms underlying this phenomenon remain unclear.In this study,we systematically investigated the influence of pressure on the co-nonsolvency effect of single-chain and multi-chain homopolymers in binary mixed good-solvent systems using molecular dynamics simulations.Our results show that the co-nonsolvency-induced chain conformation transition and aggregation behavior significantly depend on pressure in allsingle-chain and multi-chain systems.In single-chain systems,at low pressures,the polymer chain maintains a collapsed state over a wide range of co-solvent fractions(x-range)owing to the co-nonsolvency effect.As the pressure increases,the x-range of the collapsed state gradually narrows,ac-companied by a progressive expansion of the chain.In multichain systems,polymer chains assemble into approximately spherical aggregates over a broad x-range at low pressures owing to the co-nonsolvency effect.Increasing the pressure reduces the x-range for forming aggregates and leads to the formation of loose aggregates or even to a state of dispersed chains at some x-range.These findings indicate that increasing the pressure can weaken or even offset the co-nonsolvency effect in some x-range,which is in good agreement with the experimental observations.Quantitative analysis of the radial density distributions and radial distribution functions reveals that,with increasing pressure,(1)the densities of both polymers and co-solvent molecules within aggregates decrease,while that of the solvent molecule increases;and(2)the effective interac-tions between the polymer and the co-solvent weaken,whereas those between the polymer and solvent strengthen.This enhances the incorpo-ration of solvent molecules within the chains,thereby weakening or even suppressing the chain aggregation.Our study not only elucidates the regulatory mechanism of pressure on the microscopic chain conformations and aggregation behaviors of polymers,but also may provide theo-retical guidance for designing smart polymericmaterials based on mixed solvents.
基金University of Manchester and the China Scholarship Council,Royal Society,UK,Grant/Award Number:IECNSFC211366National Natural Science Foundation of China,Grant/Award Numbers:5247415,52174133Natural Science Foundation of Jiangsu Province of China,Grant/Award Number:BK20240107。
文摘Understanding the effects of temperature on the hydro-mechanical behavior of compacted bentonite is important for performance assessments of bentonitebased buffer,backfill,and sealing systems in deep geological disposal of high-level radioactive wastes.Motivated by such applications,most past experimental studies were focused on highly compacted and high-quality bentonite.Such degrees of dry densities may not be economically or technically feasible for other emerging applications,including as an alternative material to cement in plugging and abandonment of wells.A bespoke high-pressure high-temperature constant rate of strain(CRS)apparatus was developed for the work reported here to conduct a series of tests for evaluating the hydro-mechanical response of compacted bentonite to elevated temperatures.Experiments were performed with bentonite specimens with high impurity contents at a range of dry densities(1.1,1.4,and 1.7 Mg/m^(3))and temperatures between 20 and 80℃.The results show that temperature increase leads to the decrease of swelling pressure for all studied densities.Larger reductions of swelling pressure were observed with increasing dry densities,suggesting the possibility of a larger exchange of pore water in the microstructure system of the clay.The transfer of water from micropores to macropores at elevated temperatures is shown to be a key controlling process at high-density compacted bentonite by which temperature affects the swelling pressure and hydraulic conductivity.
基金supported by the National Natural Science Foundation of China(Grant No.11804288)the Natural Science Foundation of Henan(Grant No.232300420120)。
文摘The Casimir pressure plays an important role in the adhesion stability of nanofilms at submicro scales.In this work,the Casimir pressure of peptide films deposited on a layered substrate is investigated.Three types of semi-infinite substrates,i.e.,silica,silicon and gold,are considered.The buffer layer between the peptide film and substrate consists of silicon or silica.The switching sign of the Casimir pressure can be controlled in a region ranging from about 130 nm to 1000 nm,depending on the thickness of the buffer layer and the substrate.The results suggest that the critical thickness of peptide films for Casimir equilibrium increases(or decreases)by increasing the thickness of the silicon(or silica)buffer film.The influences of wetting and electrolyte screening on the Casimir pressure are also investigated.Our finding provides a theoretical guide for the adhesion stability of peptide films in organic electronics.
基金supported by the National Key research and Development Program of China(No.2022YFB4003001).
文摘The mechanical properties,microstructure and second phase precipitation behavior of flange forgings for high-pressure hydrogen storage vessels at different tempering temperatures(620–700℃)were studied.The results showed that when tempered at 620–680°C,the main microstructure of the test steel was tempered sorbite,and the main microstructure of tempered steel changed to martensite at 700℃.At 700℃,the dislocation density increased and some retained austenite existed.With the tempering temperature increasing,the yield strength showed a decreasing trend,the formation of fresh martensite made the tensile strength first decrease and then increase slightly,the impact energy at−40℃increased first and then decreased,and the impact energy at 660℃had the maximum value.The precipitates of MC type were mainly(Mo,V,Ti)C.The test steel had excellent strength and toughness matching at 660℃tempering,the tensile strength at different cross section locations was above 750 MPa,the impact energy was above 200 J at−40℃,and the relative percentage reduction of area(ZH2/ZN2)was above 75%at hydrogen environment of 6.3 MPa.
基金funded by the Hebei Provincial Party School of the CPC(Hebei Institute of Administration)Innovation Engineering Research Project(National Social Science Fund Cultivation Special)Nanjing University of Finance and Economics Major Special Teaching Reform Project“Research on Personalized Learning Mode and Implementation Path for College Students under the Background of Smart Education”the China Postdoctoral Science Foundation(Grant number:2019M662309).
文摘Background:In the field of organizational behavior,various aspects that have an impact on employee well-being gradually become a focus of attention.Among them,performance pressure,which is a component of workplace stressors that has a great influence on employees’job performance as well as well-being,has been little studied.Therefore,this paper constructs a research model,which uses workplace anxiety as a mediating variable and vocational delay of gratification as a moderating variable,to explore the impact of performance pressure on employee well-being.Methods:Reliable data were collected by questionnaire method and data analysis was conducted with the help of SPSS 26.0.In this paper,the data statistics are carried out by correlation analysis,mediation effect analysis,and moderating effect analysis,and the regression analysis is further studied.Results:The finding shows that performance pressure impacts employee well-being negatively,and workplace anxiety has a significant negative impact on employee well-being.When the workplace anxiety variable is added,the negative impact of performance pressure on employee well-being is still significant.Therefore,it can be verified that workplace anxiety plays an intermediary role in the influencing mechanism of performance pressure on employee well-being.While high vocational delay satisfaction weakens the influence of performance pressure on employee well-being.It’s interesting that under the adjustment of low delayed gratification,low-performance pressure will lead to higher employee well-being,and the organization’s conscious reduction of performance pressure is conducive to improving employeewell-being,and under the adjustment of high delayed gratification,low-performance pressure leads to higher employee well-being,and high-performance pressure leads to lower employee well-being,which shows the weakening effect of high delayed gratification,that means vocational delay gratification plays a negative regulating role in the influencing mechanism of performance pressure and employee well-being.Conclusion:Under the mediating role of workplace anxiety,performance pressure has a significant negative impact on employee well-being,and in this influence mechanism,vocational delay gratification plays a significant negative moderating role.
基金supported by National Natural Science Foundation of China (Nos.52377141 and 92371105)。
文摘Dielectric barrier discharges(DBDs)are primarily utilized as efficient sources of large-volume diffuse plasmas.However,the synergistic interaction of certain key plasma factors limits their broader application.In the present paper,we report numerical investigations of the effects of voltage amplitude in dual-frequency excitation on atmospheric DBDs using a 50 kHz/5 MHz frequency combination.Our results indicate that varying the voltages for low frequency(LF)and radio frequency(RF)significantly influences the electron dynamics during discharge,resulting in distinct spatio-temporal distributions of electron and metastable particle densities.These findings contribute to the regulation of discharges under atmospheric pressure conditions and facilitate the attainment of non-equilibrium and nonlinear plasma parameters.
基金Supported by the National Natural Science Foundation of China(No.51909154)Shanghai Engineering Research Center of Ship Intelligent Maintenance and Energy Efficiency(No.20DZ2252300).
文摘Using natural gas(NG)as the primary fuel helps alleviate the fossil fuel crisis while reducing engine soot and nitrogen oxide(NO_(X))emissions.In this paper,the influences of a novel split injection concept on an NG high pressure direct injection(HPDI)engine are examined.Four typical split injection strategies,namely split pre-injection of pilot diesel(PD)and NG,split post-injection of PD and NG,split pre-injection of NG,and split post-injection of PD,were developed to investigate the influences on combustion and emissions.Results revealed that split pre injection of NG enhanced the atomization of PD,whereas the split post-injection of NG lowered the temperature in the core region of the PD spray,resulting in the deterioration of combustion.The effect of the split injection strategy on indicated thermal efficiency exceeded 7.5%.Split pre-injection was favorable to enhancing thermal efficiency,whereas split post-injection was not.Ignition delay,combustion duration,and premixed combustion time proportion were affected by injection strategies by 3.8%,50%,and 19.7%,respectively.Split pre-injection increased CH_(4) emission in the exhaust.Split post-injection,especially split post-injection of PD and NG,reduced the unburned CH_(4) emission by approximately 30%.When the split post-injection ratio was less than 30%,the trade-off between NO_(X) and soot was interrupted.The distribution range of hydroxyl radicals was expanded by pre-injection,and NO_(X) was generated in the region where the NG jet hit the wall.This paper provides valuable insights into the optimization of HPDI injection parameters.
基金supported by the National Key R&D Program of China(Grant No.2023YFB2503800)。
文摘Lithium plating is a detrimental phenomenon in lithium-ion cells that compromises both functionality and safety.This study investigates electro-chemo-mechanical behaviors of lithium plating in lithium iron phosphate pouch cells under different external pressures.Atomic force microscopy nanoindentation is performed on the graphite electrode to analyze the influence of external pressure on solid-electrolyte interphase(SEI),revealing that the mechanical strength of SEI,indicated by Young's modulus,increases with the presence of external pressure.Then,an improved phase field model for lithium plating is developed by incorporating electrochemical parameterization based on nonequilibrium thermodynamics.The results demonstrate that higher pressure promotes lateral lithium deposition,covering a larger area of SEI.Moreover,electrochemical impedance spectroscopy and thickness measurements of the pouch cells are conducted during overcharge,showing that external pressure suppresses gas generation and thus increases the proportion of lithium deposition among galvanostatic overcharge reactions.By integrating experimental results with numerical simulations,it is demonstrated that moderate pressure mitigates SEI damage during lithium plating,while both insufficient and excessive pressure may exacerbate it.This study offers new insights into optimizing the design and operation of lithium iron phosphate pouch cells under external pressures.
基金work was supported by the Central University Basic Research Fund of China(B230201059and No.B240201155)the water science and technology special fund of Xinjiang Uygur Autonomous Region(No.XSKJ-2023-30)funded by China Power Construction Group research project(Grant No.DJ-HXGG-2023-16).
文摘The deteriorated bearing capacity and nonlinear expansion deformation of weakly cemented Xiyu conglomerate under complex water environments and stress disturbances pose significant risks to the safety of stratum engineering construction.In this study,to precisely comprehend the influences of pore pressure(P_(w))and stress path on the deformation characteristics,dilation behavior,and damage evolution of Xiyu conglomerate,a series of triaxial monotonic loading and cyclic loading-unloading tests were conducted on saturated Xiyu conglomerate with varied confining pressures(σ_(3))and pore pressures.The results indicate that as P_(w)increases,the secant modulus,unloading modulus,and loading modulus decrease,but increase with risingσ_(3).Additionally,P_(w)accelerates the onset of dilatancy,whereasσ_(3)delays it.Asσ_(3)increases,the peak stress,crack damage stress,and residual strength increase,while these parameters decrease with increasing P_(w).A positive correlation exists between the effective confining pressure and the effective axial stress.Furthermore,an increase in P_(w)results in a greater maximum dilation angle,which decreases with increasingσ_(3).The failure mode is mainly a tensile-shear mixed failure mode.The high pore pressure and cyclic loading stress path aggravate the deterioration of strength and failure mode of the weakly cemented Xiyu conglomerate.Finally,a new damage variable and conceptual model are proposed and discussed.The findings provide insight into the damage and failure mechanism of the Xiyu conglomerate under pore pressure and cyclic disturbance,offering a crucial experimental foundation for the design and construction of hydropower projects in the Xiyu conglomerate layer.
基金funded by the Research on Intelligent Mining Geological Model and Ventilation Model for Extremely Thin Coal Seam in Heilongjiang Province,China(2021ZXJ02A03)the Demonstration of Intelligent Mining for Comprehensive Mining Face in Extremely Thin Coal Seam in Heilongjiang Province,China(2021ZXJ02A04)the Natural Science Foundation of Heilongjiang Province,China(LH2024E112).
文摘Coal dust explosions are severe safety accidents in coal mine production,posing significant threats to life and property.Predicting the maximum explosion pressure(Pm)of coal dust using deep learning models can effectively assess potential risks and provide a scientific basis for preventing coal dust explosions.In this study,a 20-L explosion sphere apparatus was used to test the maximum explosion pressure of coal dust under seven different particle sizes and ten mass concentrations(Cdust),resulting in a dataset of 70 experimental groups.Through Spearman correlation analysis and random forest feature selection methods,particle size(D_(10),D_(20),D_(50))and mass concentration(Cdust)were identified as critical feature parameters from the ten initial parameters of the coal dust samples.Based on this,a hybrid Long Short-Term Memory(LSTM)network model incorporating a Multi-Head Attention Mechanism and the Sparrow Search Algorithm(SSA)was proposed to predict the maximum explosion pressure of coal dust.The results demonstrate that the SSA-LSTM-Multi-Head Attention model excels in predicting the maximum explosion pressure of coal dust.The four evaluation metrics indicate that the model achieved a coefficient of determination(R^(2)),root mean square error(RMSE),mean absolute percentage error(MAPE),and mean absolute error(MAE)of 0.9841,0.0030,0.0074,and 0.0049,respectively,in the training set.In the testing set,these values were 0.9743,0.0087,0.0108,and 0.0069,respectively.Compared to artificial neural networks(ANN),random forest(RF),support vector machines(SVM),particle swarm optimized-SVM(PSO-SVM)neural networks,and the traditional single-model LSTM,the SSA-LSTM-Multi-Head Attention model demonstrated superior generalization capability and prediction accuracy.The findings of this study not only advance the application of deep learning in coal dust explosion prediction but also provide robust technical support for the prevention and risk assessment of coal dust explosions.
基金Supported by Gansu Youth Science and Technology Fund Project:20JR10RA344.
文摘Objective To investigate the effects of moxibustion on wound healing and evaluate whether the efficacy of moxibustion at different temperatures varies.Additionally,to explore the mechanism by which moxibustion regulates the phosphatidylinositol 3-kinase(PI3K)/protein kinase B(AKT)/mammalian rapamycin target protein(mTOR)signaling pathway on wound healing and cell apoptosis.Methods A total of 90 SPF-grade SD rats were randomly divided into six groups(15 rats per group):control group,model group,recombinant bovine basic fibroblast growth factor gel(rb-bFGF)group,moxibustion group A[temperature(42±1)℃],moxibustion group B[temperature(45±1)℃],and moxibustion group C[temperature(48±1)℃].Except the control group,the interventions were conducted in the other groups with pressure ulcer induced by ischemia/reperfusion injury.In the control group,povidone-iodine was administered at the knee joint.In the model group,after povidone-iodine applied at the pressure ulcer,petroleum jelly gauze was bandaged.In the rb-bFGF group,after povidone-iodine applied at the pressure ulcer,rb-bFGF was smeared and petroleum jelly gauze was bandaged.In the moxibustion group A,the suspending moxibustion with moxa stick was delivered 3 cm to 5 cm above the ulcer.The paperless temperature recorder probe was placed on the wound surface where moxibustion was delivered,and the real-time temperature was monitored and adjusted,kept at(42±1)℃.The moxibustion temperature was kept at(45±1)℃ in the moxibustion group B,and(48±1)℃ in the moxibustion group C.The intervention lasted 14 days in each group.The wound healing rates were compared on the 3,5,7 and 14 days after the first intervention among the 6 groups.After 14-day intervention respectively,the histopathological changes were observed with HE staining,apoptosis was detected with TUNEL method and flow cytometry;VEGF-A protein expression determined with immunohistochemistry;the contents of Interleukin-6(IL-6),tumor necrosis factor-α(TNF-α)and transforming growth factor-β(TGF-β)in serum with ELISA,and PI3K/AKT/mTOR related protein and mRNA expression was with Western blotting and qRT-PCR in wound tissues of each group.Results Regarding the intervention effects,(1)compared with the control group,the model group showed significant inflammatory infiltration in wound tissues,higher levels of cell apoptosis,and elevated serum levels of IL-6,TNF-αand TGF-β(P<0.05);(2)compared with the model group,the rb-bFGF group and 3 moxibustion groups showed higher wound healing rates(P<0.05),reduced inflammatory infiltration in the wound tissues,lower levels of cell apoptosis,and decreased serum levels of IL-6,TNF-αand TGF-β(P<0.05).Among the moxibustion groups,group C showed significantly better results than group A(P<0.01).Regarding the mechanism,(1)compared with the control group,the model group exhibited significantly higher protein and mRNA expression levels of PI3K/AKT/mTOR signal pathway components(P<0.05);(2)compared with the model group,the rb-bFGF group and 3 moxibustion groups showed lower protein and mRNA expression levels of PI3K/AKT/mTOR signal pathway components(P<0.05).Among the moxibustion groups,group C showed significantly higher expression levels than group A(P<0.01).Conclusion Moxibustion significantly promotes wound healing,with high-temperature moxibustion being more effective than low-temperature moxibustion in reducing the expression of inflammatory factors and cell apoptosis,thereby improving wound healing rates.It is presented that the higher moxibustion temperature,the higher wound healing rate,which may be associated with the regulation of PI3K/AKT/mTOR signal pathway with moxibustion.
基金Projects(52278395,52208409) supported by the National Natural Science Foundation of ChinaProject(2022JJ40531) supported by the Natural Science Foundation of Hunan Province,China。
文摘Because of actual requirement,shield machine always excavates with an inclined angle in longitudinal direction.Since many previous studies mainly focus on the face stability of the horizontal shield tunnel,the effects of tensile strength cut-off and pore water pressure on the face stability of the longitudinally inclined shield tunnel are not well investigated.A failure mechanism of a longitudinally inclined shield tunnel face is constructed based on the spatial discretization technique and the tensile strength cut-off criterion is introduced to modify the constructed failure mechanism.The pore water pressure is introduced as an external force into the equation of virtual work and the objective function of the chamber pressure of the shield machine is obtained.Moreover,the critical chamber pressure of the longitudinally inclined shield tunnel is computed by optimal calculation.Parametric analysis indicates that both tensile strength cut-off and pore water pressure have a significant impact on the chamber pressure and the range of the collapse block.Finally,the theoretical results are compared with the numerical results calculated by FLAC3D software which proves that the proposed approach is effective.
