Magnesium and its alloys have been initially applied to biliary tract surgery.Currently,few reports on the degradation behavior of magnesium in the bile environment were investigated.Thus,in-depth research on the degr...Magnesium and its alloys have been initially applied to biliary tract surgery.Currently,few reports on the degradation behavior of magnesium in the bile environment were investigated.Thus,in-depth research on the degradation behavior of Mg and its alloys in bile is beneficial to the further application of Mg in biliary tract surgery.In this study,the degradation behavior of HP-Mg(HPM)and Mg-2 wt.%Zn(MZ2)alloys in human bile and Hanks balanced salt solution(HBSS)was systematically investigated.The MZ2 alloy biliary stent was implanted into the porcine common bile duct to study the degradation behavior of MZ2 alloy in vivo,and to verify the biosafety of MZ2 alloys degradation in the bile duct.It was found that the degradation product layer formed by MZ2 alloys in bile consisted of three layers,including organic matter(fatty acid,etc.),calcium and magnesium phosphate,and Mg(OH)2/MgO,respectively from the outside to the inside.The multi-layered degradation product layer slowed down the corrosion of the Mg matrix.During the 21 days of stent implantation,the degradation rate of the MZ2 stent was about 0.83 mm/y,there was no blockage and stenosis of the tube diameter,and the bile drainage function was normal.展开更多
BACKGROUND Older patients with liver cancer often experience impaired pulmonary function post-surgery,increasing complications and recovery challenges.AIM To investigate the effects of evidence-based stratified manage...BACKGROUND Older patients with liver cancer often experience impaired pulmonary function post-surgery,increasing complications and recovery challenges.AIM To investigate the effects of evidence-based stratified management and stepwise training in the perioperative pulmonary rehabilitation of older patients with liver cancer,providing a basis for clinical application.METHODS In total,120 older patients with liver cancer who underwent surgery at our hospital between February 2023 and February 2025 were selected and randomly divided into study and control groups,with 60 patients in each group.All the patients underwent radical hepatectomy.Postoperatively,the control group received routine nursing management and rehabilitation training,while the study group received evidence-based stratified management combined with stepwise training for a continuous intervention period of one week.Time to first ambulation,length of hospital stays,and average hospitalization costs were recorded.Oxygen saturation(SPO_(2))was measured on postoperative day 1 and day 3.The 6-minute walk distance and Borg scale scores were assessed on postoperative day 1 and day 7,respectively.The postoperative complication rates were recorded.RESULTS The study group had a significantly shorter time to first ambulation,shorter hospital stays,and lower average hospitalization costs than the control group(P<0.05).On postoperative day 1,there was no significant difference in SPO_(2)between the groups(P>0.05);however,on postoperative day 3,the study group had significantly higher SPO_(2)(P<0.05).On postoperative day 7,the study group showed a significantly longer 6-minute walk distance and lower Borg scores than the control group(P<0.05).The incidence of postoperative complications in the study group was 3.33%,which was significantly lower than that in the control group(13.33%;P<0.05).CONCLUSION Implementing evidence-based stratified management combined with stepwise training in the perioperative pulmonary rehabilitation of older patients with liver cancer is improves lung function,reduces complications,and promotes effective recovery,demonstrating significant clinical value.展开更多
This study examines the potential impacts o climate change on Lake Biwa,Japan’s largest freshwate lake,with a focus on temperature,wind speed,and pre cipitation variations.Leveraging data from the IPCC Sixth Assessme...This study examines the potential impacts o climate change on Lake Biwa,Japan’s largest freshwate lake,with a focus on temperature,wind speed,and pre cipitation variations.Leveraging data from the IPCC Sixth Assessment Report,including CCP scenarios,projecting a significant temperature rise of 3.3–5.7℃in the case o very high GHG emission power,the research investigates how these shifts may influence dissolved oxygen levels in Lake Biwa.Through a one-dimensional model incorporat ing sediment redox reactions,various scenarios where ai temperature and wind speed are changed are simulated.I is revealed that a 5℃increase in air temperature leads to decreasing 1-2 mg/L of dissolved oxygen concentrations from the surface layer to the bottom layer,while a decrease in air temperature tends to elevate 1–3 mg/L of oxygen lev els.Moreover,doubling wind speed enhances surface laye oxygen but diminishes it in deeper layers due to increased mixing.Seasonal variations in wind effects are noted with significant surface layer oxygen increases from 0.4to 0.8 mg/L during summer to autumn,increases from 0.4 to 0.8 mg/L in autumn to winter due to intensified vertica mixing.This phenomenon impacts the lake’s oxygen cycle year-round.In contrast,precipitation changes show limited impact on oxygen levels,suggesting minor influence com pared to other meteorological factors.The study suggests the necessity of comprehensive three-dimensional models that account for lake-specific and geographical factors fo accurate predictions of future water conditions.A holistic approach integrating nutrient levels,water temperature,and river inflow is deemed essential for sustainable management of Lake Biwa’s water resources,particularly in addressing precipitation variations.展开更多
The mechanical properties of stratified rocks are closely related not only to the stress state but also to the inherent structural anisotropy,which can be represented by the occurrence of bedding planes.This research ...The mechanical properties of stratified rocks are closely related not only to the stress state but also to the inherent structural anisotropy,which can be represented by the occurrence of bedding planes.This research aims to enhance the understanding of the anisotropic deformation and failure behaviors of stratified rocks by proposing a novel coupled elastoplastic-damage constitutive model.In this constitutive model,a scalar anisotropic parameter(stress-structure mixed invariant)based on the Pietruszczak–Mroz anisotropic theory is incorporated into a nonlinear yield surface,which accounts for the combined effects of the stress state and bedding structure on the anisotropic strength behaviors of stratified rocks.A damage-driven function governs the expansion and contraction of the anisotropic yield surface in the pre-peak strain hardening and post-peak strain-softening regions.The strength and deformation characteristics under multiaxial stress conditions are represented by incorporating the Lode's angle into the yield and plastic potential functions.Numerical simulations are conducted to facilitate a comparison with the conventional and true triaxial compression test data for several stratified rocks.The simulation results demonstrate good agreement with the test data,validating the effectiveness of the proposed constitutive model.This study provides theoretical and technical support for addressing engineering challenges involving stratified rocks.展开更多
Geological sequestration of carbon dioxide(CO_(2))entails the long-term storage of captured emissions from CCUS(Carbon Capture,Utilization,and Storage)facilities in deep saline aquifers to mitigate greenhouse gas accu...Geological sequestration of carbon dioxide(CO_(2))entails the long-term storage of captured emissions from CCUS(Carbon Capture,Utilization,and Storage)facilities in deep saline aquifers to mitigate greenhouse gas accumulation.Among various trapping mechanisms,dissolution trapping is particularly effective in enhancing storage security.However,the stratified structure of saline aquifers plays a crucial role in controlling the efficiency of CO_(2) dissolution into the resident brine.In this study,a two-dimensional numerical model of a stratified saline aquifer is developed,integrating both two-phase flow and mass transfer dynamics.The model captures the temporal evolution of gas saturation,reservoir pressure,and CO_(2) dissolution behavior under varying geological and operational conditions.Specifically,the effects of porosity heterogeneity,permeability distribution,and injection rate on the dissolution process are examined,and sequestration efficiencies across distinct stratigraphic layers are compared.Simulation results reveal that in the early phase of CO_(2) injection,the plume spreads radially along the lower portion of the aquifer.With continued injection,high-saturation regions expand upward and eventually accumulate beneath the shale and caprock layers.Pressure within the reservoir rises in response to CO_(2) injection,propagating both vertically and laterally.CO_(2) migration and dissolution are strongly influenced by reservoir properties,with progressive dissolution occurring in the pore spaces of individual layers.High-porosity zones favor CO_(2) accumulation and enhance local dissolution,whereas low-porosity regions facilitate vertical diffusion.An increase in porosity from 0.25 to 0.30 reduces the radial extent of dissolution in the high-permeability layer by 16.5%.Likewise,increasing permeability promotes radial dispersion;each 10 mD increment extends the CO_(2) dissolution front by approximately 18 m.Elevated injection rates intensify both vertical and lateral plume migration:every 0.25×10^(−6) m/s increase in rate yields an average 100–120 m increase in radial dissolution distance within high-permeability zones.展开更多
This study examined gender differences in modal choice among residents of coastal communities of Yenagoa metropolis in Bayelsa State, Nigeria. The Four-Step model of transportation planning and modal choice provided t...This study examined gender differences in modal choice among residents of coastal communities of Yenagoa metropolis in Bayelsa State, Nigeria. The Four-Step model of transportation planning and modal choice provided the theoretical basis for this study. A survey research design involving a stratified sampling technique was adopted. The descriptives on transport modes, amount and time spent revealed that 10 (76.9%) males and 3 (23.1%) females preferred bicycle as means of transportation, 7 (58.3%) males and 5 (41.7%) females preferred motorcycle, while a significant proportion 90 (53.9%) males and 77 (46.1%) females preferred tricycle, 80 (63.0%) males and 47 (37.0%) females preferred cars/taxis, and 12 (46.2%) males and 14 (53.8%) females preferred mass transit bus. However, 14 (46.7%) males and 16 (53.3%) females in marshy terrain and coastal locations preferred canoes and boats. The result of the logistic regression model revealed that gender modal preference is more likely to be influenced by mode of transportation with a beta weight of 1.140, safety considerations 1.139, ownership of transport 1.135 and distance to place of work 1.073. Hence, this study recommends that a combination of these factors should be incorporated into transport planning to achieve effective transport planning and sustainable development in the Yenagoa metropolis.展开更多
The backfill should keep stable in the primary stope when mining an adjacent secondary stope in subsequent open stoping mining methods,and the large-size mined-out area is usually backfilled by multiple backfilling be...The backfill should keep stable in the primary stope when mining an adjacent secondary stope in subsequent open stoping mining methods,and the large-size mined-out area is usually backfilled by multiple backfilling before the recovery of a secondary stope,resulting in a layered structure of backfill in stope.Therefore,it is significant to investigate the deformation responses and mechanical properties of stratified cemented tailings backfill(SCTB)with different layer structures to remain self-standing as an artificial pillar in the primary stope.The current work examined the effects of enhance layer position(1/3,1/2,and 2/3)and thickness ratio(0,0.1,0.2,and 0.3)on the mechanical properties,deformation,energy evolution,microstructures,and failure modes of SCTB.The results demonstrate that the incorporation of an enhance layer significantly strengthens the deformation and strength of SCTB.Under a confining pressure of 50 kPa,the peak deviatoric stress rises from 525.6 to 560.3,597.1,and 790.5 kPa as the thickness ratio of enhance layer is increased from 0 to 0.1,0.2,and 0.3,representing a significant increase of 6.6%,13.6%,and 50.4%.As the confining pressure increases,the slopes of the curves in the elastic stage become steep,and the plastic phase is extended accordingly.Additionally,the incorporation of the enhance layer significantly improves the energy storage linit of SCTB specimen.As the thickness ratio of the enhance layer increases from 0 to 0.1,0.2,and 0.3,the elastic energy rises from 0.54 to 0.67,0.84,and 1.00 MJ·m^(-3),representing a significant increase of 24.1%,55.6%,and 85.2%.The internal friction angles and cohesions of the SCTB specimens are higher than those of the CTB specimens,however,the cohesion is more susceptible to enhance layer position and thickness ratio than the internal friction angle.The failure style of the SCTB specimen changes from shear failure to splitting bulging failure and shear bulging failure with the presence of an enhance layer.The crack propagation path is significantly blocked by the enhance layer.The findings are of great significance to the application and stability of the SCTB in subsequent stoping backfilling mines.展开更多
To ensure the airtightness of salt cavern oil storage in layered salt rock,this study investigates the porosity and permeability characteristics and seepage laws of the surrounding rock of the storage caverns under th...To ensure the airtightness of salt cavern oil storage in layered salt rock,this study investigates the porosity and permeability characteristics and seepage laws of the surrounding rock of the storage caverns under the erosion of crude oil and brine.Salt rock,interlayer,and cap rock samples from the Jintan salt cavern storage in Jiangsu,China,were used.The porosity and permeability changes of the samples were measured under different static water pressures,different erosion times,and different working conditions(crude oil erosion and brine erosion).Finally,based on the theory of single-phase liquid stable seepage,liquid seepage models for interlayer and cap rock were established.The results show that the porosity and permeability parameters of the surrounding rock are not affected by stress changes under different working conditions.The wetting of crude oil covers the pore structure inside the surrounding rock,enhancing its airtightness macroscopically and thus favoring the long-term airtightness of the salt cavern oil storage.In contrast,brine erosion destroys the pore structure inside the surrounding rock,severely deteriorating its airtightness macroscopically,which seriously affects the lifespan of the storage cavern and is detrimental to the long-term airtightness of the salt cavern oil storage.Based on the assumption of single-phase liquid stable seepage,the leakage of the storage cavern was calculated.The calcu-lations of gas and liquid leakage were corrected according to the airtightness standards of gas storage caverns and combined with existing simulation parameters,which to some extent proved the accuracy of the liquid seepage models for interlayer and cap rock.展开更多
Iread with great interest the recent article by Shin,et al.[1]the authors present an important exploration into the use of drug-coated balloon(DCB)in patients aged≥75 years,a demographic increasingly encountered in m...Iread with great interest the recent article by Shin,et al.[1]the authors present an important exploration into the use of drug-coated balloon(DCB)in patients aged≥75 years,a demographic increasingly encountered in modern cardiovascular practice.The authors conducted a retrospective analysis involving 2050 elderly patients(aged≥75 years)undergoing successful percutaneous coronary intervention(PCI).展开更多
Stratified flow is a common phenomenon in horizontal tubes of two-phase flow systems. However, the existing methods for calculating the wetted angle of the flat interface model and the central angle of the two-circle ...Stratified flow is a common phenomenon in horizontal tubes of two-phase flow systems. However, the existing methods for calculating the wetted angle of the flat interface model and the central angle of the two-circle model rely on solving implicit transcendental equations, which require iterative numerical root-finding methods,thereby introducing computational complexity and inefficiency. This paper proposes the high-precision explicit approximate solutions for the two models, directly correlating the geometric parameters with the flow parameters, thus significantly enhancing the efficiency and accuracy of two-phase flow analysis.展开更多
We present a method to unify the calculation of Green＇s functions for an electromagnetic（EM） transmitting source embedded in a homogeneous stratified medium.A virtual interface parallel to layer interfaces is intro...We present a method to unify the calculation of Green＇s functions for an electromagnetic（EM） transmitting source embedded in a homogeneous stratified medium.A virtual interface parallel to layer interfaces is introduced through the source location.The potentials for Green＇s function are derived by decomposing the partial wave solutions to Helmholtz＇s equations into upward and downward within boundaries.The amplitudes of the potentials in each stratum are obtained recursively from the initial amplitudes at the source level.The initial amplitudes are derived by coupling with the transmitting sources and following the discontinuity of the tangential electric and magnetic fields at the source interface.Only the initial terms are related to the transmitting sources and thus need to be modified for different transmitters,whereas the kernel connected with the stratified media stays unchanged.Hence,the present method can be easily applied to EM transmitting sources with little modification.The application of the proposed method to the marine controlled-source electromagnetic method（MCSEM） demonstrates its simplicity and flexibility.展开更多
Test results of reducing two stroke motorcycle emissions with new type carburettors and electronic fuel injection systems are presented. Analyses and comparison between different systems are discussed. The adoption o...Test results of reducing two stroke motorcycle emissions with new type carburettors and electronic fuel injection systems are presented. Analyses and comparison between different systems are discussed. The adoption of electronically controlled injection and corresponding electronic control technique is an effective measure of prolonged vitality to improve emissions from two stroke motorcycles. Suggestions about the strategic steps of China′s motorcycle emission control are proposed.展开更多
The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher voc...The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher vocational education and quality-oriented education. This thesis argues for the need of stratified English teaching in high vocational colleges.展开更多
Multiple filling of gobs will lead to a layered structure of the backfill.To explore the influence of layering structure on the mechanical properties and failure modes of backfill,different backfill specimens were pre...Multiple filling of gobs will lead to a layered structure of the backfill.To explore the influence of layering structure on the mechanical properties and failure modes of backfill,different backfill specimens were prepared with a cement/sand ratio of 1:4,a slurry concentration of 75%,and backfilling times of 1,2,3 and 4,separately.Triaxial cyclic loading and unloading experiments were carried out.The results show that with an increase in backfilling time,the peak strength of backfill decreases as a polynomial function and the peak strain increases as an exponential function.The cyclic load enhances the linear characteristic of backfill deformation.The loading and unloading deformation moduli have a linear negative correlation with the backfilling time.The unloading deformation modulus is always slightly higher than the loading deformation modulus.The failure modes of stratified backfill are mainly characterized by conjugate shear failure at the upper layer and tensile failure across the layer plane,and there is usually no damage in the lower layer away from the loading area.展开更多
An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of th...An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of the Yangtze Block during 140–135 Ma under extensional tectonic circumstances following the collision between the North China and Yangtze blocks. The main orebodies of the Dongguashan copper deposit, a typical diplogenetic stratified deposit among many polymetallic ore deposits in China, are hosted by strata between Upper Devonian sandstone and Carboniferous limestone, and its mineralization was genetically related to the Qingshanjiao intrusive. The Rb-Sr isotopic isochron of the Qingshanjiao intrusive yields an age of about 136.5±1.4 Ma. The ore-forming fluid reflected by the inclusion fluid in quartz veins is characterized by high temperature and high salinity, and its age was also determined by Rb -Sr isotope dating as 134±11 Ma. Oxygen and hydrogen isotope composition data suggest that the ore-forming fluid was derived mainly from magmatism. By integrating these isotopic dating data, characteristics of fluid inclusions and the geology of the deposit, the mineralization of the Dongguashan copper deposit is divided into two stages. First, a stratiform sedimentary deposit or protore layer formed in the Late Devonian to the Early Carboniferous, while in the second stage the pre-existing protore was superimposed by hydrothermal fluid that was derived from the Yanshanian magmatic activities occurring around 135 Ma ago. This two-stage mineralization formed the Dongguashan statiform copper deposit. Associated “porphyry” mineralization found in the bottom of and in surrounding intrusive rocks of the orebodies might have occurred in the same period as a second-stage mineralization of this deposit.展开更多
In order to capture the mechanism of roadway instability in deep mines, a new approach of Physically Finite Elemental Slab Assemblage (PFESA) is proposed in order to construct a large-scale physical model simulating t...In order to capture the mechanism of roadway instability in deep mines, a new approach of Physically Finite Elemental Slab Assemblage (PFESA) is proposed in order to construct a large-scale physical model simulating the geologically horizontal strata. We carried out physical modeling on the deformation and failure processes of roadways subjected to a plane loading scheme. Our laboratory tests were based on work which incorporated infrared (IR) detection, IR radiation temperature (IRT) statistics, image feature extraction and 2D Fourier transformation, from resulting thermographies. The IRT characterizes the mechanical responses from the roadway after loading with two stages, i.e., IRT evolving at higher levels corresponded to shallow mining (≤500 m) during which the roadway deformed gradually (referred to as the "steady deformation stage"); IRT evolving in a quasi-cyclical manner with multiple peaks corresponded to deep mining (800–2600 m), in which the failure mode for the roadway are dominated by breakage and collapse (called the "unsteady deformation stage"). The IR images and 2D Fourier spectra illustrate detailed information in terms of initiation, nucleation and coalescence of the damage to rock masses and the eventual failure of roadways subject to external loading.展开更多
Combining the advantages of the stratified sampling and the importance sampling, a stratified importance sampling method （SISM） is presented to analyze the reliability sensitivity for structure with multiple failure...Combining the advantages of the stratified sampling and the importance sampling, a stratified importance sampling method （SISM） is presented to analyze the reliability sensitivity for structure with multiple failure modes. In the presented method, the variable space is divided into several disjoint subspace by n-dimensional coordinate planes at the mean point of the random vec- tor, and the importance sampling functions in the subspaces are constructed by keeping the sampling center at the mean point and augmenting the standard deviation by a factor of 2. The sample size generated from the importance sampling function in each subspace is determined by the contribution of the subspace to the reliability sensitivity, which can be estimated by iterative simulation in the sampling process. The formulae of the reliability sensitivity estimation, the variance and the coefficient of variation are derived for the presented SISM. Comparing with the Monte Carlo method, the stratified sampling method and the importance sampling method, the presented SISM has wider applicability and higher calculation efficiency, which is demonstrated by numerical examples. Finally, the reliability sensitivity analysis of flap structure is illustrated that the SISM can be applied to engineering structure.展开更多
Because of gravitational differentiation of multi-phase fluids, gas-water flow is usually stratified in highly inclined or horizontal gas wells. By using electrode arrays to scan flowing fluids, electromagnetic tomogr...Because of gravitational differentiation of multi-phase fluids, gas-water flow is usually stratified in highly inclined or horizontal gas wells. By using electrode arrays to scan flowing fluids, electromagnetic tomography can identify the flow patterns of mixed fluid from the different electrical properties of gas and water. The responses for different gas-water interface locations were calculated and then physical measurements were undertaken. We compared the results of the numerical simulation with the experimental data, and found that the response characteristics were consistent in the circumstances of uniform physical fields and stratified flows. By analyzing the signal characteristics, it is found that, with the change of the interface location, the response curves showed ＂steps＂ whose position and width were decided by the location of fluid interface. The measurement accuracy of this method depended on the vertical distance between adjacent electrodes. The results showed that computer simulation can simulate the measurement of the electromagnetic tomography accurately, so the physical experiment can be replaced.展开更多
BACKGROUND:The study aimed to evaluate the predictive role of interleukin-6(IL-6)and chronic obstructive pulmonary disease(COPD)assessment test(CAT)score in mechanical ventilation(MV)in COPD patients at the acute exac...BACKGROUND:The study aimed to evaluate the predictive role of interleukin-6(IL-6)and chronic obstructive pulmonary disease(COPD)assessment test(CAT)score in mechanical ventilation(MV)in COPD patients at the acute exacerbation stage in the emergency department(ED).METHODS:For a one-year period,among adult patients in the ED who met the criteria of acute exacerbation of COPD,158 who received MV within 48 hours after admission were compared to 294 who didn't require MV within the same period after admission.IL-6 level and CAT score were compared between the two groups.The predicted value of IL-6 and CAT score was assessed by logistic regression analysis and a receiver operating characteristic(ROC)curve.RESULTS:The IL-6 and CAT scores in the 158 MV patients were much higher than those without.IL-6 and CAT scores were independent predictors of MV within 48 hours using logistic regression analysis(IL-6:odds ratio[OR]1.053,95%confidence interval[CI]1.039–1.067,P<0.001;CAT score:OR 1.122,95%CI 1.086–1.159,P<0.001).The combination of IL-6 and CAT scores(area under ROC curve[AUC]0.826,95%CI 0.786–0.866,P<0.001)improved the accuracy of predicting MV within 48 hours when compared with IL-6(AUC 0.752,95%CI 0.703–0.800,P<0.001)and CAT scores alone(AUC 0.739,95%CI 0.692–0.786,P<0.001).The sensitivity and specificity were 69.6%,74.1%,75.32%and 63.6%,respectively.CONCLUSION:The combined of IL-6 and CAT scores is useful for evaluating the risk of COPD patients at acute exacerbation in ED,and can provide a predictive value for MV or not within 48 hours.展开更多
基金supported by the Sci-ence and technology commission of Shanghai Municipal-ity(No.19441905600)the Shanghai Jiao Tong University Interdisciplinary(Biomedical Engineering)Research Fund(No.ZH2018ZDA09)+2 种基金Clinical Research Plan of SHDC(No.SHDC2020CR3036B)China Postdoctoral Science Founda-tion(No.2021M702090)Changshu Science and Technology Program(Industrial)Project(No.CG202107).
文摘Magnesium and its alloys have been initially applied to biliary tract surgery.Currently,few reports on the degradation behavior of magnesium in the bile environment were investigated.Thus,in-depth research on the degradation behavior of Mg and its alloys in bile is beneficial to the further application of Mg in biliary tract surgery.In this study,the degradation behavior of HP-Mg(HPM)and Mg-2 wt.%Zn(MZ2)alloys in human bile and Hanks balanced salt solution(HBSS)was systematically investigated.The MZ2 alloy biliary stent was implanted into the porcine common bile duct to study the degradation behavior of MZ2 alloy in vivo,and to verify the biosafety of MZ2 alloys degradation in the bile duct.It was found that the degradation product layer formed by MZ2 alloys in bile consisted of three layers,including organic matter(fatty acid,etc.),calcium and magnesium phosphate,and Mg(OH)2/MgO,respectively from the outside to the inside.The multi-layered degradation product layer slowed down the corrosion of the Mg matrix.During the 21 days of stent implantation,the degradation rate of the MZ2 stent was about 0.83 mm/y,there was no blockage and stenosis of the tube diameter,and the bile drainage function was normal.
文摘BACKGROUND Older patients with liver cancer often experience impaired pulmonary function post-surgery,increasing complications and recovery challenges.AIM To investigate the effects of evidence-based stratified management and stepwise training in the perioperative pulmonary rehabilitation of older patients with liver cancer,providing a basis for clinical application.METHODS In total,120 older patients with liver cancer who underwent surgery at our hospital between February 2023 and February 2025 were selected and randomly divided into study and control groups,with 60 patients in each group.All the patients underwent radical hepatectomy.Postoperatively,the control group received routine nursing management and rehabilitation training,while the study group received evidence-based stratified management combined with stepwise training for a continuous intervention period of one week.Time to first ambulation,length of hospital stays,and average hospitalization costs were recorded.Oxygen saturation(SPO_(2))was measured on postoperative day 1 and day 3.The 6-minute walk distance and Borg scale scores were assessed on postoperative day 1 and day 7,respectively.The postoperative complication rates were recorded.RESULTS The study group had a significantly shorter time to first ambulation,shorter hospital stays,and lower average hospitalization costs than the control group(P<0.05).On postoperative day 1,there was no significant difference in SPO_(2)between the groups(P>0.05);however,on postoperative day 3,the study group had significantly higher SPO_(2)(P<0.05).On postoperative day 7,the study group showed a significantly longer 6-minute walk distance and lower Borg scores than the control group(P<0.05).The incidence of postoperative complications in the study group was 3.33%,which was significantly lower than that in the control group(13.33%;P<0.05).CONCLUSION Implementing evidence-based stratified management combined with stepwise training in the perioperative pulmonary rehabilitation of older patients with liver cancer is improves lung function,reduces complications,and promotes effective recovery,demonstrating significant clinical value.
基金Open Access funding provided by Kobe UniversityThis research was partially performed by the Environment Research and Technology Development Fund(2RL-2301)of the Environmental Restoration and Conservation Agency provided by Ministry of the Environment of Japan.
文摘This study examines the potential impacts o climate change on Lake Biwa,Japan’s largest freshwate lake,with a focus on temperature,wind speed,and pre cipitation variations.Leveraging data from the IPCC Sixth Assessment Report,including CCP scenarios,projecting a significant temperature rise of 3.3–5.7℃in the case o very high GHG emission power,the research investigates how these shifts may influence dissolved oxygen levels in Lake Biwa.Through a one-dimensional model incorporat ing sediment redox reactions,various scenarios where ai temperature and wind speed are changed are simulated.I is revealed that a 5℃increase in air temperature leads to decreasing 1-2 mg/L of dissolved oxygen concentrations from the surface layer to the bottom layer,while a decrease in air temperature tends to elevate 1–3 mg/L of oxygen lev els.Moreover,doubling wind speed enhances surface laye oxygen but diminishes it in deeper layers due to increased mixing.Seasonal variations in wind effects are noted with significant surface layer oxygen increases from 0.4to 0.8 mg/L during summer to autumn,increases from 0.4 to 0.8 mg/L in autumn to winter due to intensified vertica mixing.This phenomenon impacts the lake’s oxygen cycle year-round.In contrast,precipitation changes show limited impact on oxygen levels,suggesting minor influence com pared to other meteorological factors.The study suggests the necessity of comprehensive three-dimensional models that account for lake-specific and geographical factors fo accurate predictions of future water conditions.A holistic approach integrating nutrient levels,water temperature,and river inflow is deemed essential for sustainable management of Lake Biwa’s water resources,particularly in addressing precipitation variations.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52109143 and 12062026)the Open Research Fund of State Key Laboratory of Simulation and Regulation of Water Cycle in River Basin(China Institute of Water Resources and Hydropower Research)(Grant No.IWHRSKL-KF202305).
文摘The mechanical properties of stratified rocks are closely related not only to the stress state but also to the inherent structural anisotropy,which can be represented by the occurrence of bedding planes.This research aims to enhance the understanding of the anisotropic deformation and failure behaviors of stratified rocks by proposing a novel coupled elastoplastic-damage constitutive model.In this constitutive model,a scalar anisotropic parameter(stress-structure mixed invariant)based on the Pietruszczak–Mroz anisotropic theory is incorporated into a nonlinear yield surface,which accounts for the combined effects of the stress state and bedding structure on the anisotropic strength behaviors of stratified rocks.A damage-driven function governs the expansion and contraction of the anisotropic yield surface in the pre-peak strain hardening and post-peak strain-softening regions.The strength and deformation characteristics under multiaxial stress conditions are represented by incorporating the Lode's angle into the yield and plastic potential functions.Numerical simulations are conducted to facilitate a comparison with the conventional and true triaxial compression test data for several stratified rocks.The simulation results demonstrate good agreement with the test data,validating the effectiveness of the proposed constitutive model.This study provides theoretical and technical support for addressing engineering challenges involving stratified rocks.
基金supported by the National Natural Science Foundation of China(No.52306187)the Fundamental Research Funds for the Central Universities of China(Grant No.3132024205)the Open Fund of Key Laboratory of Ocean Energy Utilization and Energy Conservation of Ministry of Education(Grant No.LOEC-202004).
文摘Geological sequestration of carbon dioxide(CO_(2))entails the long-term storage of captured emissions from CCUS(Carbon Capture,Utilization,and Storage)facilities in deep saline aquifers to mitigate greenhouse gas accumulation.Among various trapping mechanisms,dissolution trapping is particularly effective in enhancing storage security.However,the stratified structure of saline aquifers plays a crucial role in controlling the efficiency of CO_(2) dissolution into the resident brine.In this study,a two-dimensional numerical model of a stratified saline aquifer is developed,integrating both two-phase flow and mass transfer dynamics.The model captures the temporal evolution of gas saturation,reservoir pressure,and CO_(2) dissolution behavior under varying geological and operational conditions.Specifically,the effects of porosity heterogeneity,permeability distribution,and injection rate on the dissolution process are examined,and sequestration efficiencies across distinct stratigraphic layers are compared.Simulation results reveal that in the early phase of CO_(2) injection,the plume spreads radially along the lower portion of the aquifer.With continued injection,high-saturation regions expand upward and eventually accumulate beneath the shale and caprock layers.Pressure within the reservoir rises in response to CO_(2) injection,propagating both vertically and laterally.CO_(2) migration and dissolution are strongly influenced by reservoir properties,with progressive dissolution occurring in the pore spaces of individual layers.High-porosity zones favor CO_(2) accumulation and enhance local dissolution,whereas low-porosity regions facilitate vertical diffusion.An increase in porosity from 0.25 to 0.30 reduces the radial extent of dissolution in the high-permeability layer by 16.5%.Likewise,increasing permeability promotes radial dispersion;each 10 mD increment extends the CO_(2) dissolution front by approximately 18 m.Elevated injection rates intensify both vertical and lateral plume migration:every 0.25×10^(−6) m/s increase in rate yields an average 100–120 m increase in radial dissolution distance within high-permeability zones.
文摘This study examined gender differences in modal choice among residents of coastal communities of Yenagoa metropolis in Bayelsa State, Nigeria. The Four-Step model of transportation planning and modal choice provided the theoretical basis for this study. A survey research design involving a stratified sampling technique was adopted. The descriptives on transport modes, amount and time spent revealed that 10 (76.9%) males and 3 (23.1%) females preferred bicycle as means of transportation, 7 (58.3%) males and 5 (41.7%) females preferred motorcycle, while a significant proportion 90 (53.9%) males and 77 (46.1%) females preferred tricycle, 80 (63.0%) males and 47 (37.0%) females preferred cars/taxis, and 12 (46.2%) males and 14 (53.8%) females preferred mass transit bus. However, 14 (46.7%) males and 16 (53.3%) females in marshy terrain and coastal locations preferred canoes and boats. The result of the logistic regression model revealed that gender modal preference is more likely to be influenced by mode of transportation with a beta weight of 1.140, safety considerations 1.139, ownership of transport 1.135 and distance to place of work 1.073. Hence, this study recommends that a combination of these factors should be incorporated into transport planning to achieve effective transport planning and sustainable development in the Yenagoa metropolis.
基金financially supported by the Fundamental Research Funds for the Central Universities,China(No.2023JCCXNY01)Guangxi Key Technologies R&D Program,China(No.2022AB31022).
文摘The backfill should keep stable in the primary stope when mining an adjacent secondary stope in subsequent open stoping mining methods,and the large-size mined-out area is usually backfilled by multiple backfilling before the recovery of a secondary stope,resulting in a layered structure of backfill in stope.Therefore,it is significant to investigate the deformation responses and mechanical properties of stratified cemented tailings backfill(SCTB)with different layer structures to remain self-standing as an artificial pillar in the primary stope.The current work examined the effects of enhance layer position(1/3,1/2,and 2/3)and thickness ratio(0,0.1,0.2,and 0.3)on the mechanical properties,deformation,energy evolution,microstructures,and failure modes of SCTB.The results demonstrate that the incorporation of an enhance layer significantly strengthens the deformation and strength of SCTB.Under a confining pressure of 50 kPa,the peak deviatoric stress rises from 525.6 to 560.3,597.1,and 790.5 kPa as the thickness ratio of enhance layer is increased from 0 to 0.1,0.2,and 0.3,representing a significant increase of 6.6%,13.6%,and 50.4%.As the confining pressure increases,the slopes of the curves in the elastic stage become steep,and the plastic phase is extended accordingly.Additionally,the incorporation of the enhance layer significantly improves the energy storage linit of SCTB specimen.As the thickness ratio of the enhance layer increases from 0 to 0.1,0.2,and 0.3,the elastic energy rises from 0.54 to 0.67,0.84,and 1.00 MJ·m^(-3),representing a significant increase of 24.1%,55.6%,and 85.2%.The internal friction angles and cohesions of the SCTB specimens are higher than those of the CTB specimens,however,the cohesion is more susceptible to enhance layer position and thickness ratio than the internal friction angle.The failure style of the SCTB specimen changes from shear failure to splitting bulging failure and shear bulging failure with the presence of an enhance layer.The crack propagation path is significantly blocked by the enhance layer.The findings are of great significance to the application and stability of the SCTB in subsequent stoping backfilling mines.
基金financial supports of the National Natural Science Foundation of China Youth Science Foundation Project(52204152,52204111,52204153)the Postdoctoral Innovation Talent Support Program(BX2020275)the Postdoctoral Science Foun-dation(2020M683521).
文摘To ensure the airtightness of salt cavern oil storage in layered salt rock,this study investigates the porosity and permeability characteristics and seepage laws of the surrounding rock of the storage caverns under the erosion of crude oil and brine.Salt rock,interlayer,and cap rock samples from the Jintan salt cavern storage in Jiangsu,China,were used.The porosity and permeability changes of the samples were measured under different static water pressures,different erosion times,and different working conditions(crude oil erosion and brine erosion).Finally,based on the theory of single-phase liquid stable seepage,liquid seepage models for interlayer and cap rock were established.The results show that the porosity and permeability parameters of the surrounding rock are not affected by stress changes under different working conditions.The wetting of crude oil covers the pore structure inside the surrounding rock,enhancing its airtightness macroscopically and thus favoring the long-term airtightness of the salt cavern oil storage.In contrast,brine erosion destroys the pore structure inside the surrounding rock,severely deteriorating its airtightness macroscopically,which seriously affects the lifespan of the storage cavern and is detrimental to the long-term airtightness of the salt cavern oil storage.Based on the assumption of single-phase liquid stable seepage,the leakage of the storage cavern was calculated.The calcu-lations of gas and liquid leakage were corrected according to the airtightness standards of gas storage caverns and combined with existing simulation parameters,which to some extent proved the accuracy of the liquid seepage models for interlayer and cap rock.
文摘Iread with great interest the recent article by Shin,et al.[1]the authors present an important exploration into the use of drug-coated balloon(DCB)in patients aged≥75 years,a demographic increasingly encountered in modern cardiovascular practice.The authors conducted a retrospective analysis involving 2050 elderly patients(aged≥75 years)undergoing successful percutaneous coronary intervention(PCI).
基金supported by the General Research Fund from the Research Grants Council of the Hong Kong Special Administrative Region of China (No. PolyU 15210624)。
文摘Stratified flow is a common phenomenon in horizontal tubes of two-phase flow systems. However, the existing methods for calculating the wetted angle of the flat interface model and the central angle of the two-circle model rely on solving implicit transcendental equations, which require iterative numerical root-finding methods,thereby introducing computational complexity and inefficiency. This paper proposes the high-precision explicit approximate solutions for the two models, directly correlating the geometric parameters with the flow parameters, thus significantly enhancing the efficiency and accuracy of two-phase flow analysis.
基金supported by CNSF(Granted No.40874050)Chinese High Technology Project(Granted No.2011YQ05006010)
文摘We present a method to unify the calculation of Green＇s functions for an electromagnetic（EM） transmitting source embedded in a homogeneous stratified medium.A virtual interface parallel to layer interfaces is introduced through the source location.The potentials for Green＇s function are derived by decomposing the partial wave solutions to Helmholtz＇s equations into upward and downward within boundaries.The amplitudes of the potentials in each stratum are obtained recursively from the initial amplitudes at the source level.The initial amplitudes are derived by coupling with the transmitting sources and following the discontinuity of the tangential electric and magnetic fields at the source interface.Only the initial terms are related to the transmitting sources and thus need to be modified for different transmitters,whereas the kernel connected with the stratified media stays unchanged.Hence,the present method can be easily applied to EM transmitting sources with little modification.The application of the proposed method to the marine controlled-source electromagnetic method（MCSEM） demonstrates its simplicity and flexibility.
文摘Test results of reducing two stroke motorcycle emissions with new type carburettors and electronic fuel injection systems are presented. Analyses and comparison between different systems are discussed. The adoption of electronically controlled injection and corresponding electronic control technique is an effective measure of prolonged vitality to improve emissions from two stroke motorcycles. Suggestions about the strategic steps of China′s motorcycle emission control are proposed.
文摘The practice of stratified English teaching is determined by the features of vocational education. In addition, it is an inexorable trend of current higher education reform, and also a fundamental demand of higher vocational education and quality-oriented education. This thesis argues for the need of stratified English teaching in high vocational colleges.
基金the National Natural Science Foundation of China(No.51374033)the Key Projects of the National Key Research and Development Program(No.YS2017YFSF040004).
文摘Multiple filling of gobs will lead to a layered structure of the backfill.To explore the influence of layering structure on the mechanical properties and failure modes of backfill,different backfill specimens were prepared with a cement/sand ratio of 1:4,a slurry concentration of 75%,and backfilling times of 1,2,3 and 4,separately.Triaxial cyclic loading and unloading experiments were carried out.The results show that with an increase in backfilling time,the peak strength of backfill decreases as a polynomial function and the peak strain increases as an exponential function.The cyclic load enhances the linear characteristic of backfill deformation.The loading and unloading deformation moduli have a linear negative correlation with the backfilling time.The unloading deformation modulus is always slightly higher than the loading deformation modulus.The failure modes of stratified backfill are mainly characterized by conjugate shear failure at the upper layer and tensile failure across the layer plane,and there is usually no damage in the lower layer away from the loading area.
基金supported by the National Science Foundation of China(grant Nos.49873016,40221301)the Ph.D.Programs Foundation of the Ministry of Education of China(No.20020284035)
文摘An important diplogenetic mineralization event superimposed on pre-existing exhalation sediments in the Tongling area, Anhui province, was triggered by widespread granitic magmatism along the northeastern margin of the Yangtze Block during 140–135 Ma under extensional tectonic circumstances following the collision between the North China and Yangtze blocks. The main orebodies of the Dongguashan copper deposit, a typical diplogenetic stratified deposit among many polymetallic ore deposits in China, are hosted by strata between Upper Devonian sandstone and Carboniferous limestone, and its mineralization was genetically related to the Qingshanjiao intrusive. The Rb-Sr isotopic isochron of the Qingshanjiao intrusive yields an age of about 136.5±1.4 Ma. The ore-forming fluid reflected by the inclusion fluid in quartz veins is characterized by high temperature and high salinity, and its age was also determined by Rb -Sr isotope dating as 134±11 Ma. Oxygen and hydrogen isotope composition data suggest that the ore-forming fluid was derived mainly from magmatism. By integrating these isotopic dating data, characteristics of fluid inclusions and the geology of the deposit, the mineralization of the Dongguashan copper deposit is divided into two stages. First, a stratiform sedimentary deposit or protore layer formed in the Late Devonian to the Early Carboniferous, while in the second stage the pre-existing protore was superimposed by hydrothermal fluid that was derived from the Yanshanian magmatic activities occurring around 135 Ma ago. This two-stage mineralization formed the Dongguashan statiform copper deposit. Associated “porphyry” mineralization found in the bottom of and in surrounding intrusive rocks of the orebodies might have occurred in the same period as a second-stage mineralization of this deposit.
基金Projects 2006CB202200 supported by the Special Funds for the Major State Basic Research ProjectIRT0656 by the Innovative Team Development Project of the State Educational Ministry of China
文摘In order to capture the mechanism of roadway instability in deep mines, a new approach of Physically Finite Elemental Slab Assemblage (PFESA) is proposed in order to construct a large-scale physical model simulating the geologically horizontal strata. We carried out physical modeling on the deformation and failure processes of roadways subjected to a plane loading scheme. Our laboratory tests were based on work which incorporated infrared (IR) detection, IR radiation temperature (IRT) statistics, image feature extraction and 2D Fourier transformation, from resulting thermographies. The IRT characterizes the mechanical responses from the roadway after loading with two stages, i.e., IRT evolving at higher levels corresponded to shallow mining (≤500 m) during which the roadway deformed gradually (referred to as the "steady deformation stage"); IRT evolving in a quasi-cyclical manner with multiple peaks corresponded to deep mining (800–2600 m), in which the failure mode for the roadway are dominated by breakage and collapse (called the "unsteady deformation stage"). The IR images and 2D Fourier spectra illustrate detailed information in terms of initiation, nucleation and coalescence of the damage to rock masses and the eventual failure of roadways subject to external loading.
基金National Natural Science Foundation of China (10572117,10802063,50875213)Aeronautical Science Foundation of China (2007ZA53012)+1 种基金New Century Program For Excellent Talents of Ministry of Education of China (NCET-05-0868)National High-tech Research and Development Program (2007AA04Z401)
文摘Combining the advantages of the stratified sampling and the importance sampling, a stratified importance sampling method （SISM） is presented to analyze the reliability sensitivity for structure with multiple failure modes. In the presented method, the variable space is divided into several disjoint subspace by n-dimensional coordinate planes at the mean point of the random vec- tor, and the importance sampling functions in the subspaces are constructed by keeping the sampling center at the mean point and augmenting the standard deviation by a factor of 2. The sample size generated from the importance sampling function in each subspace is determined by the contribution of the subspace to the reliability sensitivity, which can be estimated by iterative simulation in the sampling process. The formulae of the reliability sensitivity estimation, the variance and the coefficient of variation are derived for the presented SISM. Comparing with the Monte Carlo method, the stratified sampling method and the importance sampling method, the presented SISM has wider applicability and higher calculation efficiency, which is demonstrated by numerical examples. Finally, the reliability sensitivity analysis of flap structure is illustrated that the SISM can be applied to engineering structure.
文摘Because of gravitational differentiation of multi-phase fluids, gas-water flow is usually stratified in highly inclined or horizontal gas wells. By using electrode arrays to scan flowing fluids, electromagnetic tomography can identify the flow patterns of mixed fluid from the different electrical properties of gas and water. The responses for different gas-water interface locations were calculated and then physical measurements were undertaken. We compared the results of the numerical simulation with the experimental data, and found that the response characteristics were consistent in the circumstances of uniform physical fields and stratified flows. By analyzing the signal characteristics, it is found that, with the change of the interface location, the response curves showed ＂steps＂ whose position and width were decided by the location of fluid interface. The measurement accuracy of this method depended on the vertical distance between adjacent electrodes. The results showed that computer simulation can simulate the measurement of the electromagnetic tomography accurately, so the physical experiment can be replaced.
基金supported by grants from Dongzhimen Hospital Fund of Special Talent(2018RC01)Beijing University of Chinese Medicine Fund of Project(2019-JYB-XJSJJ-025)
文摘BACKGROUND:The study aimed to evaluate the predictive role of interleukin-6(IL-6)and chronic obstructive pulmonary disease(COPD)assessment test(CAT)score in mechanical ventilation(MV)in COPD patients at the acute exacerbation stage in the emergency department(ED).METHODS:For a one-year period,among adult patients in the ED who met the criteria of acute exacerbation of COPD,158 who received MV within 48 hours after admission were compared to 294 who didn't require MV within the same period after admission.IL-6 level and CAT score were compared between the two groups.The predicted value of IL-6 and CAT score was assessed by logistic regression analysis and a receiver operating characteristic(ROC)curve.RESULTS:The IL-6 and CAT scores in the 158 MV patients were much higher than those without.IL-6 and CAT scores were independent predictors of MV within 48 hours using logistic regression analysis(IL-6:odds ratio[OR]1.053,95%confidence interval[CI]1.039–1.067,P<0.001;CAT score:OR 1.122,95%CI 1.086–1.159,P<0.001).The combination of IL-6 and CAT scores(area under ROC curve[AUC]0.826,95%CI 0.786–0.866,P<0.001)improved the accuracy of predicting MV within 48 hours when compared with IL-6(AUC 0.752,95%CI 0.703–0.800,P<0.001)and CAT scores alone(AUC 0.739,95%CI 0.692–0.786,P<0.001).The sensitivity and specificity were 69.6%,74.1%,75.32%and 63.6%,respectively.CONCLUSION:The combined of IL-6 and CAT scores is useful for evaluating the risk of COPD patients at acute exacerbation in ED,and can provide a predictive value for MV or not within 48 hours.
