期刊文献+
共找到281,374篇文章
< 1 2 250 >
每页显示 20 50 100
Coulomb stressing rate changes and seismicity dynamics associated with slow slip events in south-central Alaska
1
作者 ShanShan Li XingLei Li Bing Xu 《Earth and Planetary Physics》 2025年第2期289-308,共20页
Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter ... Two long-term slow slip events(SSEs) in Lower Cook Inlet, Alaska, were identified by Li SS et al.(2016). The earlier SSE lasted at least 9 years with M_(w) ~7.8 and had an average slip rate of ~82 mm/year. The latter SSE, occurring in a similar area, lasted approximately 2 years with M_(w) ~7.2 and an average slip rate of ~91 mm/year. To test whether these SSEs triggered earthquakes near the slow slip area, we calculated the Coulomb stressing rate changes on receiver faults by using two fault geometry definitions: nodal planes of focal mechanism solutions of past earthquakes, and optimally oriented fault planes. Regions in the shallow slab(30–60 km) that experienced a significant increase in the Coulomb stressing rate due to slip by the SSEs showed an increase in seismicity rates during SSE periods. No correlation was found in the volumes that underwent a significant increase in the Coulomb stressing rate during the SSE within the crust and the intermediate slab. We modeled variations in seismicity rates by using a combination of the Coulomb stress transfer model and the framework of rate-and-state friction. Our model indicated that the SSEs increased the Coulomb stress changes on adjacent faults,thereby increasing the seismicity rates even though the ratio of the SSE stressing rate to the background stressing rate was small. Each long-term SSE in Alaska brought the megathrust updip of the SSE areas closer to failure by up to 0.1–0.15 MPa. The volumes of significant Coulomb stress changes caused by the Upper and Lower Cook Inlet SSEs did not overlap. 展开更多
关键词 slow slip events Coulomb stressing rate change seismicity rate change receiver fault rate–state stress transfer model seismogenic zone megathrust failure
在线阅读 下载PDF
Determinants of high sessile serrated lesion detection:Role of faecal occult blood test and colonoscopy quality indicators
2
作者 Harry Williams Natalie R Dierick +2 位作者 Christina Lee Praka Sundaralingam Stuart N Kostalas 《World Journal of Gastrointestinal Endoscopy》 2025年第8期79-90,共12页
BACKGROUND Sessile serrated lesions(SSLs)are premalignant polyps implicated in up to 30%of colorectal cancers.Australia reports high SSL detection rates(SSL-DRs),yet with marked variability(3.1%-24%).This substantial ... BACKGROUND Sessile serrated lesions(SSLs)are premalignant polyps implicated in up to 30%of colorectal cancers.Australia reports high SSL detection rates(SSL-DRs),yet with marked variability(3.1%-24%).This substantial variation raises concerns about missed lesions and post-colonoscopy colorectal cancer.This study investigates determinants associated with SSL-DR variation in regional Australia.AIM To study how patient,clinical,and colonoscopy factors are associated with SSL detection in a regional Australian practice.We aimed to contribute high-detection data to the literature by analyzing the association of SSL detection with various determinants.METHODS This retrospective,cross-sectional analysis examined 1450 colonoscopies performed at Port Macquarie Gastroenterology during 2023.Sigmoidoscopies and repeat procedures were excluded.Multivariate logistic regression analyzed associations between SSL detection and patient demographics,clinical indications,procedural factors,and comorbidities.RESULTS The overall SSL-DR was 30.7%.Multivariate analysis identified several independent predictors:Clinical indication,bowel preparation quality,inflammatory bowel disease status,and serrated polyposis syndrome.The faecal occult blood test positive(FOBT)(+)cohort showed the highest predicted SSL detection probability(39.8%),while clinical symptoms showed the lowest(22.3%).After adjustment,SSL detection odds were 2.3 times greater among FOBT(+)patients than those with clinical symptoms(adjusted odds ratio=2.30,95%confidence interval:1.20-4.40,P=0.004).CONCLUSION SSL-DR as a quality indicator requires contextualization regarding clinical indications,bowel preparation quality,and comorbidities.There was a significantly higher prevalence of SSLs in FOBT(+)patients.Despite comprehensive adjustment,this study cannot fully explain the wide SSL-DR variation in Australia,highlighting the need for standardized detection protocols and further research to ensure optimal cancer prevention outcomes. 展开更多
关键词 Sessile serrated lesion Adenoma detection rate Faecal occult blood test Polyp detection rate DYSPLASIA COLONOSCOPY PREVALENCE
暂未订购
Shortage of storage carbohydrates mainly determines seed abscission in Torreya grandis 'Merrillii'
3
作者 Tao Liu Xiaolong Zhao +6 位作者 Guangxia Zhu Caoliang Jin Jingwei Yan Jinwei Suo Weiwu Yu Yuanyuan Hu Jiasheng Wu 《Horticultural Plant Journal》 2025年第2期619-632,共14页
Torreya grandis'Merrillii'is a well-known nut in South China with high nutritional value.Severe premature seed abscission limits the industrial development of T.grandis by causing serious economic losses.Howev... Torreya grandis'Merrillii'is a well-known nut in South China with high nutritional value.Severe premature seed abscission limits the industrial development of T.grandis by causing serious economic losses.However,the physiological mechanisms of seed abscission in T.grandis remain poorly understood.To gain insight into the relationships between carbohydrate status and seed abscission,three-year-old seed-bearing branches were taken as representative materials for the entire tree.Furthermore,the time course of changes in the photosynthetic rate and the non-structural carbohydrate(NSC)dynamics were monitored in the main sources(the one-year-old and two-year-old shoots),and the dry weight and NSC levels of sinks(the seeds,current female cone cluster,and current vegetative cluster)across all seed development stages were recorded.The cumulative seed abscission rate significantly increased,reaching 91.5%from 0 to 72 days after seed protrusion time(SPT).NSC levels in the main sources significantly decreased by 56%-79%,accompanied by a significantly increased photosynthesis rate of 17.1%-49.1%during that period and increased NSC levels in the three sinks.The gene expression level of cell wall invertase(TgCWIN)was significantly correlated with sucrose,fructose,and glucose levels.The carbon storage capacity of the main sources significantly decreased from 6.03 to3.14 mmol C·d^(-1),with a stable photosynthetic capacity,from 0 to 72 days after SPT,whereas the carbon demand of the three sinks showed a continuously increasing trend from 3.14 to 7.71 mmol C·d^(-1).In addition,sucrose supplementation significantly decreased the cumulative seed abscission rate.These results suggest that storage carbohydrates play a major role in the regulatory mechanism of seed abscission in T.grandis.Our study provides a theoretical basis for improving T.grandis yield through establishing a better carbon balance between sources and sinks using timely fertilization or proper pruning procedures. 展开更多
关键词 Storage carbohydrates Seasonal photosynthetic rate Non-structural carbohydrates Seed abscission
在线阅读 下载PDF
Influences of strain rate on mechanical behaviors of unsaturated and quasi-saturated loess under varying drainage conditions 被引量:1
4
作者 Tongwei Zhang Sheng Li +2 位作者 Hengxing Lan Huyuan Zhang Fanyu Zhang 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第2期1163-1181,共19页
Although time-dependent deformation of geomaterials underpins slope-failure prediction models,the influence of strain rate on shearing strength and deformation behavior of loess remains unclear.The consolidated undrai... Although time-dependent deformation of geomaterials underpins slope-failure prediction models,the influence of strain rate on shearing strength and deformation behavior of loess remains unclear.The consolidated undrained(CU)and drained(CD)triaxial testing elucidated the impact of strain rate(0.005–0.3 mm/min)on strength envelopes,deformation moduli,pore pressures,and dilatancy characteristics of unsaturated and quasi-saturated loess.Under drained conditions with a controlled matric suction of 50 kPa,increasing strain rates from 0.005 mm/min to 0.011 mm/min induced decreases in failure deviatoric stress(qf),initial deformation modulus(Ei),and cohesion(c),while friction angles remained unaffected.Specimens displayed initial contractive volumetric strains transitioning to dilation across varying confining pressures.Higher rates diminished contractive volumetric strains and drainage volumes,indicating reduced densification and strength in the shear zone.Under undrained conditions,both unsaturated and quasi-saturated(pore pressure coefficient B=0.75)loess exhibited deteriorating mechanical properties with increasing rates from 0.03 mm/min to 0.3 mm/min.For unsaturated loess,reduced contractive volumetric strains at higher rates manifested relatively looser structures in the pre-peak stress phase.The strength decrement in quasi-saturated loess arose from elevated excess porewater pressures diminishing effective stresses.Negative porewater pressures emerged in quasi-saturated loess at lower confining pressures and strain rates.Compared to previous studies,the qf and Ei exhibited rate sensitivity below threshold values before attaining minima with marginal subsequent influence.The underlying mechanism mirrors the transition from creep to accelerated deformation phase of landslides. 展开更多
关键词 Unsaturated loess Strain rate Shearing strength Deformation modulus Drainage conditions
在线阅读 下载PDF
Equilibrium Strategies in M/M/1 Retrial Queues with Variable Service Rate
5
作者 LIU Yuanyuan YAN Zhaozeng YANG Qin 《应用概率统计》 北大核心 2025年第3期448-466,共19页
We consider a single server constant retrial queue,in which a state-dependent service policy is used to control the service rate.Customer arrival follows Poisson process,while service time and retrial time are exponen... We consider a single server constant retrial queue,in which a state-dependent service policy is used to control the service rate.Customer arrival follows Poisson process,while service time and retrial time are exponential distributions.Whenever the server is available,it admits the retrial customers into service based on a first-come first-served rule.The service rate adjusts in real-time based on the retrial queue length.An iterative algorithm is proposed to numerically solve the personal optimal problem in the fully observable scenario.Furthermore,we investigate the impact of parameters on the social optimal threshold.The effectiveness of the results is illustrated by two examples. 展开更多
关键词 variable service rate retrial queues real-time adaptability equilibrium strategies ALGORITHM
在线阅读 下载PDF
Optimal Investment Strategy for an Insurer in Two Currency Markets
6
作者 ZHOU Qianqian 《应用概率统计》 北大核心 2025年第1期1-16,共16页
In this paper,we study the optimal investment problem of an insurer whose surplus process follows the diffusion approximation of the classical Cramer-Lundberg model.Investment in the foreign markets is allowed,and the... In this paper,we study the optimal investment problem of an insurer whose surplus process follows the diffusion approximation of the classical Cramer-Lundberg model.Investment in the foreign markets is allowed,and therefore,the foreign exchange rate model is incorporated.Under the allowing of selling and borrowing,the problem of maximizing the expected exponential utility of terminal wealth is studied.By solving the corresponding Hamilton-Jacobi-Bellman equations,the optimal investment strategies and value functions are obtained.Finally,numerical analysis is presented. 展开更多
关键词 Cramer-Lundberg model exponential utility Hamilton-Jacobi-Bellman equation optimal investment strategy foreign exchange rate
在线阅读 下载PDF
A review of the experimental and numerical studies on the compression behavior of the additively produced metallic lattice structures at high and low strain rates
7
作者 Muhammad Arslan Bin Riaz Mustafa Guden 《Defence Technology(防务技术)》 2025年第7期1-49,共49页
Recent advances in additive manufacturing have enabled the construction of metallic lattice structures with tailored mechanical and functional properties.One potential application of metallic lattice struc-tures is in... Recent advances in additive manufacturing have enabled the construction of metallic lattice structures with tailored mechanical and functional properties.One potential application of metallic lattice struc-tures is in the impact load mitigation where an external kinetic energy is absorbed by the deformation/crushing of lattice cells.This has motivated a growing number of experimental and numerical studies,recently,on the crushing behavior of additively produced lattice structures.The present study overviews the dynamic and quasi-static crushing behavior of additively produced Ti64,316L,and AlSiMg alloy lattice structures.The first part of the study summarizes the main features of two most commonly used additive processing techniques for lattice structures,namely selective-laser-melt(SLM)and electro-beam-melt(EBM),along with a description of commonly observed process induced defects.In the second part,the deformation and strain rate sensitivities of the selected alloy lattices are outlined together with the most widely used dynamic test methods,followed by a part on the observed micro-structures of the SLM and EBM-processed Ti64,316L and AlSiMg alloys.Finally,the experimental and numerical studies on the quasi-static and dynamic compression behavior of the additively processed Ti64,316L,and AlSiMg alloy lattices are reviewed.The results of the experimental and numerical studies of the dynamic properties of various types of lattices,including graded,non-uniform strut size,hollow,non-uniform cell size,and bio-inspired,were tabulated together with the used dynamic testing methods.The dynamic tests have been noted to be mostly conducted in compression Split Hopkinson Pressure Bar(SHPB)or Taylor-and direct-impact tests using the SHPB set-up,in all of which relatively small-size test specimens were tested.The test specimen size effect on the compression behavior of the lattices was further emphasized.It has also been shown that the lattices of Ti64 and AlSiMg alloys are relatively brittle as compared with the lattices of 316L alloy.Finally,the challenges associated with modelling lattice structures were explained and the micro tension tests and multi-scale modeling techniques combining microstructural characteristics with macroscopic lattice dynamics were recommended to improve the accuracy of the numerical simulations of the dynamic compression deformations of metallic lattice structures. 展开更多
关键词 Metallic lattice structures Additive manufacturing Strain rate sensitivity MICROSTRUCTURE Dynamic compression High strain rate loading MODELLING
在线阅读 下载PDF
An effective approach for correlating Na^(+) concentrations with sweating rates in wearable sweat sensing platform
8
作者 Anwei He Xiaohe Wang +6 位作者 Liang Zhang Haolong Zhang Xingli Xu Chenyang Yu Yongquan Ma Wei Wei Pengfei Niu 《Nanotechnology and Precision Engineering》 2025年第1期58-67,共10页
Accurately correlating the sweating rate and the concentration of biomarkers in sweat is essential in many sweat-based diagnostic applications.These two measurements are always done simultaneously in wearable sweat se... Accurately correlating the sweating rate and the concentration of biomarkers in sweat is essential in many sweat-based diagnostic applications.These two measurements are always done simultaneously in wearable sweat sensing platforms.However,concentration measurements of biomarkers are always delayed on the timeline compared with their production,whereas there is no such delay for sweating rate.Thus,a timeline mismatch exists between these two measurements.This means that the concentration vs rate correlation constructed on the basis of such measurements will deviate from the actual correlation.This study demonstrates the existence of this mismatch and explains its cause using sweat Na^(+)measurements.It also proposes an effective approach that applies a point-by-point compensation for the delay between Na+measurements and the real-time sweating rates,such that the data on the repositioned concentration vs time curve correspond to exactly the same point on the timeline as their production.A vison sensor is developed to measure the sweating rate with high accuracy at a frequency of more than 0.1 Hz.Off-body and on-body measurements of sweating rate and Na^(+)concentration are carried out,and concentration–rate correlations are constructed using both measured and repositioned concentration curves.The least squares and random forest methods are employed to fit the constructed correlations and evaluate the reliability of the proposed approach.The use of the repositioned concentration curve gives a constructed correlation that is much closer to the actual one.This study indicates the necessity to rearrange sensor-measured biomarker concentration vs time curves when correlations of concentration with sweating rate need to be constructed and proposes a practical point-by-point data repositioning strategy for doing so.The results presented here will benefit the study of sweat biomarkers with unclear correlations with sweating rate,as well as providing a basis for the development of more reliable sweat-based diagnostic methods. 展开更多
关键词 Wearable sweat monitoring Sweating rate Concentration rate correlation Timeline mismatch Machine learning
在线阅读 下载PDF
Impact of convergence rate and slab dip angle on island-arc magma generation
9
作者 Yongliang BAI Wenzhao ZHANG +4 位作者 Shiguo WU Dongdong DONG Xuan MU Jiahao TIAN Yuanpeng LIU 《Journal of Oceanology and Limnology》 2025年第5期1425-1440,共16页
Island-arc magmatism is a crucial process in the Earth’s crustal growth.However,how the island-arc magma production rate(MPR)changes and the key influencing factors remains unclear.This study employs numerical models... Island-arc magmatism is a crucial process in the Earth’s crustal growth.However,how the island-arc magma production rate(MPR)changes and the key influencing factors remains unclear.This study employs numerical models to simulate island-arc growth,incorporating slab dehydration,mantle hydration and melting,and melt extraction.In addition,the impacts of convergence rate and slab dip angle on island-arc magma production were studied.Results suggest that,(1)MPR increases with higher convergence rates;high convergence rates enhance slab water transport efficiency and mantle wedge convection,thereby promoting water fraction and temperature in potential molten regions;(2)MPR initially rises and then falls as the slab dip angle varies from 30°to 45°,and to 60°.This variation is closely tied to water content in the wedge rather than mantle temperature.However,a higher slab dip promotes dehydration towards the potential-melting mantle wedge,which causes water to ascend to shallow areas and reduces the area of the potential molten region.Ultimately,a dip angle of 45°is optimal for retaining the most suitable water fraction and mantle wedge area,thereby maintaining the largest MPR;(3)convergence rate variation has a much larger influence on magma production rate than dip angle variation.When the convergence rate varies from 2 to 10 cm/a,the largest time-averaged MPR is 64.0 times the smallest one,whereas when the slab dip varies from 30°to 60°,the largest time-averaged MPR is only 3.5 times the smallest one.These findings align with numerous instances observed in modern-day subduction zones. 展开更多
关键词 island-arc magmatism production rate(MPR) convergence rate slab dip angle mantle wedge temperature hydration fraction mantle melting
在线阅读 下载PDF
On load dependence of detachment rate of kinesin motor
10
作者 Xiao-Xuan Shi Yao Wang +1 位作者 Yu-Ru Liu Ping Xie 《Chinese Physics B》 2025年第1期498-505,共8页
Kinesin is an archetypal microtubule-based molecular motor that can generate force to transport cargo in cells. The load dependence of the detachment rate is an important factor of the kinesin motor, the determination... Kinesin is an archetypal microtubule-based molecular motor that can generate force to transport cargo in cells. The load dependence of the detachment rate is an important factor of the kinesin motor, the determination of which is critically related to the chemomechanical coupling mechanism of the motor. Here, we use three models for the load dependence of the detachment rate of the kinesin motor to study theoretically and numerically the maximal force generated and microtubuleattachment duration of the motor. By comparing the theoretical and numerical results with the available experimental data,we show that only one model can explain well the available experimental data, indicating that only this model can be applicable to the kinesin motor. 展开更多
关键词 KINESIN detachment rate generated force chemomechanical coupling mechanism optical trapping
原文传递
Park Integrated Energy System Optimization Considering Carbon Excess Ratio and Electric Vehicle Coupling
11
作者 Yanjie Liu Ximin Cao Yanchi Zhang 《Energy Engineering》 2025年第8期3377-3398,共22页
Under the“dual carbon”goals,this paper constructs an optimization model of the comprehensive energy system in the park.A stepwise carbon excess rate mechanism and an electric vehicle coupling strategy are proposed:A... Under the“dual carbon”goals,this paper constructs an optimization model of the comprehensive energy system in the park.A stepwise carbon excess rate mechanism and an electric vehicle coupling strategy are proposed:A carbon quota trading system is established based on the baseline method,and the stepwise function is adopted to quantify the cost of excess carbon emissions;Introduce the price demand response and the two-way interaction mechanism of electric Vehicle vehicle-to-grid(V2G)to enhance the flexible regulation ability.Aiming at the uncertainty of wind and solar output,a typical scene set is generated by combining Latin hypercube sampling with the scene reduction method.The goal is to minimize the operating cost and maximize the consumption of renewable energy,and it is solved through the CPLEX solver in the MATLAB platform.Through simulation verification of the proposed models and methods in various scenarios,the simulation results show that under the coupling of the carbon excess rate trading mechanism,the demand response mechanism,and the vehicle-to-grid interaction of electric vehicles,the total daily operating cost of the system decreases by 25.3%,reduce the dual pressure of energy consumption costs and the economic environment,and achieve the coordinated optimization of economic and ecological benefits. 展开更多
关键词 Carbon excess rate electric vehicles integrated energy system user comfort
在线阅读 下载PDF
Flexibility versus Simplicity: A Comparative Study of Survival Models for HIV AIDS Failure Rates
12
作者 Nahashon Mwirigi 《Open Journal of Modelling and Simulation》 2025年第1期65-88,共24页
Modeling HIV/AIDS progression is critical for understanding disease dynamics and improving patient care. This study compares the Exponential and Weibull survival models, focusing on their ability to capture state-spec... Modeling HIV/AIDS progression is critical for understanding disease dynamics and improving patient care. This study compares the Exponential and Weibull survival models, focusing on their ability to capture state-specific failure rates in HIV/AIDS progression. While the Exponential model offers simplicity with a constant hazard rate, it often fails to accommodate the complexities of dynamic disease progression. In contrast, the Weibull model provides flexibility by allowing hazard rates to vary over time. Both models are evaluated within the frameworks of the Cox Proportional Hazards (Cox PH) and Accelerated Failure Time (AFT) models, incorporating critical covariates such as age, gender, CD4 count, and ART status. Statistical evaluation metrics, including Akaike Information Criterion (AIC), Bayesian Information Criterion (BIC), log-likelihood, and Pseudo-R2, were employed to assess model performance across diverse patient subgroups. Results indicate that the Weibull model consistently outperforms the Exponential model in dynamic scenarios, such as younger patients and those with co-infections, while maintaining robustness in stable contexts. This study highlights the trade-off between flexibility and simplicity in survival modeling, advocating for tailored model selection to balance interpretability and predictive accuracy. These findings provide valuable insights for optimizing HIV/AIDS management strategies and advancing survival analysis methodologies. 展开更多
关键词 HIV/AIDS Progression Survival Analysis Weibull Distribution Exponential Distribution Accelerated Failure Time (AFT) Model Cox Proportional Hazards (Cox PH) Model Hazard rate Modeling
暂未订购
Energy flow rate equation for river networks
13
作者 Sai-yu Yuan Jia-wei Lin Hong-wu Tang 《Water Science and Engineering》 2025年第2期221-224,共4页
Rational allocation of water flow energy in river networks is essential to addressing water-related issues in river network areas.However,current methods of calculating the spatiotemporal distribution of flow energy i... Rational allocation of water flow energy in river networks is essential to addressing water-related issues in river network areas.However,current methods of calculating the spatiotemporal distribution of flow energy in river networks lack precision and efficiency.This paper introduces a novel hydrodynamic representation,the energy flow rate,defined as the product of the flow rate and kinetic energy head,to quantify the kinetic energy stored and transported in river networks.A linear equation system for the energy flow rate in a river network has been theoretically derived,enabling rapid calculations under steady flow conditions.A simplified equation is proposed to describe the exponential decay of the energy flow rate,accompanied by potential energy conversion.The coefficients in the linear equation system are determined using control equations at flow confluence and diversion nodes.This study provides foundational insights that can be used to develop new hydrodynamic modeling strategies to regulate water flow energy and achieve coordinated management of water-related issues in river networks. 展开更多
关键词 River network Energy flow rate Hydrodynamic reconstruction Flow energy allocation Integrated management
在线阅读 下载PDF
Thermal effects on the strain rate-dependent behavior of highly compacted GMZ01 bentonite
14
作者 Pengju Qin Weimin Ye +1 位作者 Qiong Wang Yonggui Chen 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第1期453-464,共12页
Investigation of thermal effects on the strain rate-dependent properties of compacted bentonite is crucial for the long-term safety assessment of deep geological repository for disposal of high-level radioactive waste... Investigation of thermal effects on the strain rate-dependent properties of compacted bentonite is crucial for the long-term safety assessment of deep geological repository for disposal of high-level radioactive waste.In the present work,cylindrical GMZ01 bentonite specimens were compacted with suction-controlled by the vapor equilibrium technique.Then,a series of temperature-and suction-controlled stepwise constant rate of strain(CRS)tests was performed and the rate-dependent compressibility behavior of the highly compacted GMZ01 bentonite was investigated.The plastic compressibility parameterλ,the elastic compressibility parameterκ,the yield stress p0,as well as the viscous parameterαwere determined.Results indicate thatλ,κandαdecrease and p0 increases as suction increases.Upon heating,parametersλ,αand p0 decrease.It is also found that p0 increases linearly with increasing CRS in a double-logarithm coordinate.Based on the experimental results,a viscosity parameterα(s,T)was fitted to capture the effects of suction s and temperature T on the relationship between yield stress and strain rate.Then,an elastic-thermo-viscoplastic model for unsaturated soils was developed to describe the thermal effects on the rate-dependent behavior of highly compacted GMZ01 bentonite.Validation showed that the calculated results agreed well to the measured ones. 展开更多
关键词 Highly compacted bentonite rate-dependent behavior Constant rate of strain Temperature Elastic-thermo-viscoplastic model
在线阅读 下载PDF
Nighttime reactions of a series of unsaturated alcohols with NO_(3)•:Kinetics,products and mechanisms study
15
作者 Yanyong Xu Shengrui Tong +5 位作者 Weiran Li Meifang Chen Lin Hu Hailiang Zhang Sufan Wang Maofa Ge 《Journal of Environmental Sciences》 2025年第5期331-346,共16页
Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation a... Unsaturated alcohols are a class of Biogenic volatile organic compounds(BVOCs)emitted in large quantities by plants when damaged or under adverse environmental conditions,and studies on their atmospheric degradation at night are still lacking.We used chamber experiments to study the gas-phase reactions of three unsaturated alcohols,E-2-penten-1-ol,Z-2-hexen-1-ol and Z-3-hepten-1-ol,with NO_(3)radicals(NO_(3)•)during the night.The rate constants of these reactions were(11.7±1.76)×10^(−13),(8.55±1.33)×10^(−13)and(6.08±0.47)×10^(−13)cm^(3)/(molecule·s)at 298K and 760 Torr,respectively.In contrast,the reaction rate of similar substances with ozone was about 10^(−18)cm^(3)/(molecule·s),which indicates that the reaction with NO_(3)•is themain oxidation pathway for unsaturated alcohols at night.Small molecule aldehydes and ketones were the main gas-phase organic products of the reaction of three aldehydes and ketones with NO_(3)•,and the total small molecule aldehydes and ketones yields can reach between 45%-60%.They mainly originate from the breakage of alkoxy radicals,and different breakage sites determine different product distributions.In addition,the SOA yields of the three unsaturated alcohols with NO_(3)•were 7.1%±1.0%,12.5%±1.9%and 30.0%±4.5%,respectively,whichweremuch higher than those of similarly structured substances with O_(3)or OH radicals(•OH).The results of high-resolution mass spectrometry shows that the main components of Secondary organic aerosol(SOA)of the three unsaturated alcohols are dimeric compounds containing several nitrate groups,which are formed through the polymerization of oxyalkyl radicals. 展开更多
关键词 Unsaturated alcohols Reaction rate Aldehyde and ketone products Secondary organic aerosol components Reaction mechanism
原文传递
Measurement of unsaturated soil shear strength through drainedvented triaxial tests
16
作者 Yuxin Zhao Xu Li Li Liu 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第9期5709-5727,共19页
This study presents an in-depth investigation into the shear strength characteristics of unsaturated soils,focusing on the influenceof shear rate and initial water saturation(S_(r0)).Utilizing the drained-vented(DV)tr... This study presents an in-depth investigation into the shear strength characteristics of unsaturated soils,focusing on the influenceof shear rate and initial water saturation(S_(r0)).Utilizing the drained-vented(DV)triaxial test method,the present study investigated the shear strength behavior of silty clay under various shear rates and water saturation levels,and compared the outcomes with traditional suction-controlled(SC)and constant water content(CW)tests.The findingshighlight the pivotal role of excess pore water pressure dissipation during shearing,which significantlyaffects the shear strength of both saturated and unsaturated soils.Notably,for soils with high initial water saturation,a decrease in shear strength is observed with an increase in shear rate,which is attributed to the rise in pore water pressure.Conversely,for soils with low initial water saturation,the shear rate exhibits minimal impact on shear strength due to negligible water drainage.The research delineates the optimal shear rates for DV tests based on the initial water saturation:a slower rate of 0.0028 mm/min for samples with high water saturation(S_(r0)>66%)and a faster rate of 0.8 mm/min for samples with low water saturation(S_(r0)≤66%).A novel testing methodology for determining unsaturated soil shear strength under DV conditions is introduced,streamlining the measurement process and significantly reducing testing time.This method not only promises substantial cost savings but also aligns closely with natural engineering conditions,offering valuable guidance for geotechnical applications. 展开更多
关键词 Unsaturated soils Shear strength Shear rate Drained-vented(DV)triaxial test Silty clay Rapid measurement method
在线阅读 下载PDF
Two new shaped coal pillars designed to protect the subsurface pipeline in the gas-coal integrated mining field
17
作者 Yixin Zhao Jiandong Ren Zhongbo Sun 《International Journal of Mining Science and Technology》 2025年第3期325-344,共20页
In the gas-coal integrated mining field,the conventional design method of pipeline coal pillars leads to a large amount of coal pillars being unrecovered and overlooks the pipeline's safety requirements.Considerin... In the gas-coal integrated mining field,the conventional design method of pipeline coal pillars leads to a large amount of coal pillars being unrecovered and overlooks the pipeline's safety requirements.Considering the coal pillar recovery rate and pipeline's safety requirements,two new shaped coal pillar design approaches for subsurface pipelines were developed.Firstly,the deformation limitations for measuring pipeline safety are categorized into two:no deformation is permitted,and deformation is acceptable within elastic limits.Subsequently,integrating the key stratum theory(KST)and cave angle,a fishbone-shaped coal pillar design approach that does not permit pipeline deformation is established.Meanwhile,combined with the ground subsidence and the pipeline's elastic deformation limit,a grille-shaped coal pillar design approach that accepts deformation pipelines within elastic limits is established.Those two new approaches clarify parameters including mined width,coal pillar width and mined length.Finally,the case study shows that the designed mined width,coal pillar width and mined length of the fishbone-shaped coal pillar are 90,80,and 130 m,while those of the grille-shaped are 320,370,and640 m.Compared with the conventional method,the fishbone-shaped and grille-shaped coal pillar design approaches recovered coal pillar resources of 2.65×10~6and 5.81×10~6t on the premise of meeting the pipeline safety requirements,and the recovery rates increased by 20.5%and 45.0%,with expenditures representing only 56.46%and 20.02%of the respective benefits.These new approaches provide managers with diverse options for protecting pipeline safety while promoting coal pillar recovery,which is conducive to the harmonic mining of gas-coal resources. 展开更多
关键词 Subsurface pipeline Coal pillar recovery rate Safe requirement Fishbone-shaped coal pillar Grille-shaped coal pillar Gas-coal integrated mining field
在线阅读 下载PDF
Glomerular filtration rate and comorbidity factors in elderly hospitalizations 被引量:1
18
作者 Hatice Hamarat 《World Journal of Nephrology》 2025年第1期93-98,共6页
BACKGROUND With an increase in the elderly population,the frequency of hospitalizations in recent years has also risen at a rapid pace.This,in turn,has resulted in poor outcomes and costly treatments.Hospitalization r... BACKGROUND With an increase in the elderly population,the frequency of hospitalizations in recent years has also risen at a rapid pace.This,in turn,has resulted in poor outcomes and costly treatments.Hospitalization rates increase in elderly patients due to a decline in glomerular filtration rate(GFR).AIM To investigate the connection between GFR and comorbidity and reasons for hospitalization in elderly patients.METHODS We analyzed patients aged 75 years and over who were admitted to the internal medicine clinic of a tertiary hospital in Eskisehir.At admission,we calculated GFR values using the Modification of Diet in Renal Disease study formula and classified them into six categories:G1,G2,G3a,G3b,G4,and G5.We analyzed associations with hospitalization diagnoses and comorbidity factors.RESULTS The average age of the patients was 80.8 years(±4.5 years).GFR was 57.287±29.5 mL/kg/1.73 m2 in women and 61.3±31.5 mL/kg/1.73 m2 in men(P=0.106).Most patients were admitted to the hospital at G2 stage(32.8%).The main reasons for hospitalization were anemia(34.4%and 28.6%)and malnutrition(20.9%and 20.8%)in women and men,respectively(P=0.078).The most frequent comor-bidity leading to hospitalization was arterial hypertension(n=168,28%),fo-llowed by diabetes(n=166,27.7%)(P=0.001).CONCLUSION When evaluating geriatric patients,low GFR alone does not provide sufficient information.Patients’comorbid factors should also be taken into account.There is no association between low GFR during hospitalization and hospitalization-Hamarat H.Aging and GFR related diagnoses.Knowing the GFR value before hospitalization will be more informative in such studies. 展开更多
关键词 AGING Glomerular filtration rate HOSPITALIZATION COMORBIDITY Elderly hospitalizations
暂未订购
Strain rate dependence of dynamic recrystallization and texture evolution in hot compressed Mg-Gd-Er-Zr alloy 被引量:1
19
作者 Ning Ding Wenbo Du +3 位作者 Shubo Li Ke Liu Xian Du Zijian Yu 《Journal of Magnesium and Alloys》 2025年第1期161-171,共11页
Hot deformation with high strain rate has been paid more attention due to its high efficiency and low cost,however,the strain rate dependent dynamic recrystallization(DRX)and texture evolution in hot deformation proce... Hot deformation with high strain rate has been paid more attention due to its high efficiency and low cost,however,the strain rate dependent dynamic recrystallization(DRX)and texture evolution in hot deformation process,which affect the formability of metals,are lack of study.In this work,the DRX behavior and texture evolution of Mg-8Gd-1Er-0.5Zr alloy hot compressed with strain rates of 0.1 s^(−1),1 s^(−1),10 s^(−1) and 50 s^(−1) are studied,and the corresponding dominant mechanisms for DRX and texture weakening are discussed.Results indicated the DRX fraction was 20%and the whole texture intensity was 16.89 MRD when the strain rate was 0.1 s^(−1),but they were 76%and 6.55 MRD,respectively,when the strain rate increased to 50 s^(−1).The increment of DRX fraction is suggested to result from the reduced DRX critical strain and the increased dislocation density as well as velocity,while the weakened whole texture is attributed to the increased DRX grains.At the low strain rate of 0.1 s^(−1),discontinuous DRX(DDRX)was the dominant,but the whole texture was controlled by the deformed grains with the preferred orientation of{0001}⊥CD,because the number of DDRX grains was limited.At the high strain rate of 50 s^(−1),continuous DRX(CDRX)and twin-induced DRX(TDRX)were promoted,and more DRX grains resulted in orientation randomization.The whole texture was mainly weakened by CDRX and TDRX grains,in which CDRX plays a major role.The results of present work are significant for understanding the hot workability of Mg-RE alloys with a high strain rate. 展开更多
关键词 Dynamic recrystallization Texture Hot compression Strain rate Mg-Gd-Er-Zr alloy
在线阅读 下载PDF
Md CIb HLH1 modulates sugar metabolism and accumulation in apple fruits by coordinating carbohydrate synthesis and allocation 被引量:1
20
作者 Jianqiang Yu Xiaolong Liu +7 位作者 Wenyan Wang Lili Zhang Chukun Wang Quanyan Zhang Jiahui Wang Mengchi Du Lixia Sheng Dagang Hu 《Horticultural Plant Journal》 2025年第2期578-592,共15页
The content of soluble sugars is a vital parameter that indicates the quality of fleshy fruits such as apple(Malus domestica Borkh.).Studying the patterns of accumulation of soluble sugars and regulatory mechanisms as... The content of soluble sugars is a vital parameter that indicates the quality of fleshy fruits such as apple(Malus domestica Borkh.).Studying the patterns of accumulation of soluble sugars and regulatory mechanisms associated with fruit development is crucial for breeding improved fruit varieties.Here,we report that MdCIbHLH1,a low temperature-induced b HLH transcription factor,inhibits the accumulation of soluble sugars by regulating sugar-metabolizing enzyme activities,photosynthetic performance,and the expression of sugar-related genes in developing apple fruits.MdCIbHLH1 inhibits MdFBP and MdPEPCK expression,thus blocking the conversion of acids to sugars in apple fruits.We also discovered that MdCIbHLH1 decreases the photosynthetic rate and carbohydrate accumulation in apple leaves.Our results suggest that soluble sugar accumulation in apple fruits is influenced by multiple factors,including metabolic status,photosynthesis,and carbohydrate allocation.MdCIbHLH1 is critically involved in controlling the accumulation of soluble sugars by coordinating carbohydrate synthesis and allocation,thus influencing sugar transport and its metabolism during the development of apple fruits. 展开更多
关键词 Fruit quality APPLE BHLH Sugar metabolism and transportation Photosynthetic rates
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部