The integration of boronizing and austempering termed boro-austempering treatment is a new processing route for preparing high strength bainitic steel with high surface hardness and high corrosion resistance.The micro...The integration of boronizing and austempering termed boro-austempering treatment is a new processing route for preparing high strength bainitic steel with high surface hardness and high corrosion resistance.The microstructure and properties of a medium-carbon bainitic steel prepared by boro-austempering treatment were characterized and analyzed.The results show that a single Fe_(2)B layer on bainite substrate was obtained with surface hardness of~1400 HV,and the critical load for adhesive failure of borided layer reached 73.6 N.The silicon-rich α-Fe phase in transition zone was clarified as ferrite,which was formed at the beginning stage of cooling process from boronizing to low-temperature bainite transformation.Moreover,the relative potential differences between Fe_(2)B and bainite matrix,and ferrite and bainite matrix were 75 and 92 mV,respectively,with bainite matrix acting as active anode,indicating that the corrosion resistances of Fe2B and ferrite were better than that of bainite.展开更多
High-temperature confocal laser scanning microscopy(HT-CLSM)is considered as a powerful tool for in situ observation of the phase transformation of steels at elevated temperatures.It breaks the limitation that convent...High-temperature confocal laser scanning microscopy(HT-CLSM)is considered as a powerful tool for in situ observation of the phase transformation of steels at elevated temperatures.It breaks the limitation that conventional approaches on this aspect can only post-mortem the microstructure at room temperature.The working principle and major functions of HT-CLSM in initial are introduced and the utilization in details with HT-CLSM is summarized,including the behaviors of melting-solidifying,austenite reversion,as well as the austenite decomposition(formation of Widmanstätten,pearlite,acicular ferrite,bainite and martensite)in steels.Moreover,a serie of HT-CLSM images are used to explore the growth kinetic of phase at elevated temperatures with additional theoretical calculation models.Finally,the in situ HT-CLSM observations of phase transformation,combined with post-mortem electron backscatter diffraction analysis,is also summarized to elucidate the crystallographic evolution.展开更多
The effects of austenite grain size on the deformed microstructure and mechanical properties of an Fe-20Mn-6Al-0.6C-0.15Si(wt.%)low-density steel were investigated.The microstructure of the experimental steel after so...The effects of austenite grain size on the deformed microstructure and mechanical properties of an Fe-20Mn-6Al-0.6C-0.15Si(wt.%)low-density steel were investigated.The microstructure of the experimental steel after solution treatment was single austenitic phase.The austenite grain size increased with solution temperature and time.A model was established to show the relationship between temperature,time and austenite grain size for the experimental steel.In addition,as the solution temperature increased,the strength decreased,while the elongation first increased and then decreased.This decrease in elongation after solution treatment at 1100℃ for 90 min is contributed to the over-coarse austenite grains.However,after solution treatment at 900℃ for 90 min,the strength-elongation product reached the highest value of 44.4 GPa%.As the austenite grain size increased,the intensity of<111>//tensile direction fiber decreased.This was accompanied by a decrease in dislocation density,resulting in a lower fraction of low-angle grain boundaries and a lower work hardening rate.Therefore,the austenite grain size has a critical influence on the mechanical properties of the low-density steels.Coarser grains lead to a lower yield strength due to the Hall-Petch effect and a lower tensile strength because of lower dislocation strengthening.展开更多
An enantioselective catalytic method for the direct [4 + 1] annulation of yne–allylic acetates with pyrazolones has been realized by a copper-catalyzed remote strategy. A variety of enantioenriched spiropyrazolones a...An enantioselective catalytic method for the direct [4 + 1] annulation of yne–allylic acetates with pyrazolones has been realized by a copper-catalyzed remote strategy. A variety of enantioenriched spiropyrazolones are rapidly accessed in high yields with moderate to good enantiocontrol. The facile follow-up transformations highlight its potential utility in the synthesis of diverse spiropyrazolones building blocks.展开更多
The formation mechanism of acicular ferrite and its microstructural characteristics in 430 ferrite stainless steel with TiC additions were studied by theory and experiment.Using an"edge?to?edge matching"mode...The formation mechanism of acicular ferrite and its microstructural characteristics in 430 ferrite stainless steel with TiC additions were studied by theory and experiment.Using an"edge?to?edge matching"model,a 5.25 mismatch between TiC(FCC structure)and ferritic stainless steel(BCC structure)was identified,which met the mismatch requirement for the heterogeneous nucleation of 430 ferritic stainless steel.TiC was found to be an effective nucleation site for the formation of acicular ferrite in a smelting experiment,as analyzed by metallographic examination,Image-Pro Plus 6.0 analysis software,and SEM–EDS.Furthermore,small inclusions in the size of 2–4?m increased the probability of acicular ferrite nucleation,and the secondary acicular ferrite would grow sympathetically from the initial acicular ferrite to produce multi-dimensional acicular ferrites.Moreover,the addition of Ti C can increase the average microstrain and dislocation density of 430 ferrite stainless steel,as calculated by Williamson-Hall(WH)method,which could play some role in strengthening the dislocation.展开更多
The growth rates of bainite plates in an Fe-C-Mn-Si superbainitie steel were investigated by in situ observation. The lengthening rates of ferrite bainite during both cooling and isothermal holding processes were obse...The growth rates of bainite plates in an Fe-C-Mn-Si superbainitie steel were investigated by in situ observation. The lengthening rates of ferrite bainite during both cooling and isothermal holding processes were observed and the growth rates of bainite plates nucleating at grain boundaries, within grains and on preformed bainite were measured. It is indicated that the lengthening rates of bainite plates during the cooling and isothermal processes were different, and that the growth rates of bainite plates nucleating at different types of sites also demon- strated diversity. The bainite plates initiating at [vain boundaries during cooling grew the fastest, while the plates nucleating on preformed bainite did the slowest. However, the growth rate of the bainite plates nucleating at grain boundaries during isothermal transformation de- creased the most, whereas the bainite plates initiating within grains grew the fastest. In addition, the growth rate of ferrite bainite in the study supported the diffusion transformation mechanism of bainite from the viewooint of ~rowth rate.展开更多
In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel were conducted on a high-temperature laser scanning confocal microscope during continuous heating and subsequent isothermal holding at ...In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel were conducted on a high-temperature laser scanning confocal microscope during continuous heating and subsequent isothermal holding at 850, 1000, and 1100℃ for 30 min. A grain growth model was proposed based on experimental results. It is indicated that the austenite grain size increases with austenitizing temperature and holding time. When the austenitizing temperature is above 1100℃, the austenite grains grow rapidly, and abnormal austenite grains occur. In addition, the effect of heating rate on austenite grain growth was investigated, and the relation between austenite grains and bainite morphology after bainitic transformations was also discussed.展开更多
In 2012,the International Agency for Research on Cancer(IARC)classified diesel particulate matter(DPM)as a carcinogen to human.With the increased usage of diesel equipment in underground mines,miners have a high risk ...In 2012,the International Agency for Research on Cancer(IARC)classified diesel particulate matter(DPM)as a carcinogen to human.With the increased usage of diesel equipment in underground mines,miners have a high risk of over-exposure to DPM,which has drawn many concerns from the public.This study used computational fluid dynamics(CFD)to analyse the DPM dispersion and concentration distribution characteristics in an underground development face based on an onsite experiment.The DPM emitted from a moving loader under a forcing auxiliary ventilation system was simulated.The motion of the load-haul-dump(LHD)in the tunnel was represented by a dynamic mesh method.The species transport approach was applied to study the DPM behaviours.High DPM concentration zones were then identified based on the simulation results.The results could provide guidelines for work practices and be helpful to an optimum auxiliary ventilation design to reduce underground miner exposure.展开更多
The effects of aluminum addition on bainite transformation and properties of carbide-free bainitic steels containing 0.22 wt.% carbon were investigated by two different types of heat treatment processes: continuous co...The effects of aluminum addition on bainite transformation and properties of carbide-free bainitic steels containing 0.22 wt.% carbon were investigated by two different types of heat treatment processes: continuous cooling process (CCP) and isothermal transformation process (ITP). The results indicate that for the CCP treatment, Al addition significantly promoted the ferrite and bainite transformation;however, it did not significantly increase the product of tensile strength and total elongation (PSE). For the ITP treatment, Al addition significantly promoted the kinetics of bainite transformation, and thus, more bainite was formed with Al addition;however, it was found that Al addition resulted in a decrease in tensile strength and an increase in elongation of the tested bainitic steels. Moreover, the effects of Al addition on comprehensive property were profoundly dependent on austempering temperatures. When the austempering temperature was higher (430℃), PSE significantly increased with Al addition, whereas it decreased at the lower austempering temperature (400℃). Therefore, it can be concluded that the effects of Al on properties of bainitic steels were more significant at higher austempering temperatures.展开更多
Exposure to mining-induced particulate matter(PM)including coal dust and diesel particulate matter(DPM)causes severe respirat-ory diseases such as coal workers’pneumoconiosis(CWP)and lung cancer.Limited spatiotempora...Exposure to mining-induced particulate matter(PM)including coal dust and diesel particulate matter(DPM)causes severe respirat-ory diseases such as coal workers’pneumoconiosis(CWP)and lung cancer.Limited spatiotemporal resolution of current PM monitors causes miners to be exposed to unknown PM concentrations,with increased overexposure risk.Low-cost PM sensors offer a potential solution to this challenge with their capability in characterizing PM concentrations with high spatiotemporal resolution.However,their application in underground mines has not been explored.With the aim of examining the potential application of low-cost sensors in underground mines,a critical review of the present status of PM sensor research is conducted.The working principles of present PM monitors and low-cost sensors are com-pared.Sensor error sources are identified,and comprehensive calibration processes are presented to correct them.Evaluation protocols are pro-posed to evaluate sensor performance prior to deployment,and the potential application of low-cost sensors is discussed.展开更多
The purpose of this study was to analyze the value of transrectal shear-wave elastography(SWE)in combination with multivariable tools for predicting adverse pathological features before radical prostatectomy(RP).Preop...The purpose of this study was to analyze the value of transrectal shear-wave elastography(SWE)in combination with multivariable tools for predicting adverse pathological features before radical prostatectomy(RP).Preoperative clinicopathological variables,multiparametric magnetic resonance imaging(mp-MRI)manifestations,and the maximum elastic value of the prostate(Emax)on SWE were retrospectively collected.The accuracy of SWE for predicting adverse pathological features was evaluated based on postoperative pathology,and parameters with statistical significance were selected.The diagnostic performance of various models,including preoperative clinicopathological variables(model 1),preoperative clinicopathological variables+mp-MRI(model 2),and preoperative clinicopathological variables+mp-MRI+SWE(model 3),was evaluated with area under the receiver operator characteristic curve(AUC)analysis.Emax was significantly higher in prostate cancer with extracapsular extension(ECE)or seminal vesicle invasion(SVI)with both P<0.001.The optimal cutoff Emax values for ECE and SVI were 60.45 kPa and 81.55 kPa,respectively.Inclusion of mp-MRI and SWE improved discrimination by clinical models for ECE(model 2 vs model 1,P=0.031;model 3 vs model 1,P=0.002;model 3 vs model 2,P=0.018)and SVI(model 2 vs model 1,P=0.147;model 3 vs model 1,P=0.037;model 3 vs model 2,P=0.134).SWE is valuable for identifying patients at high risk of adverse pathology.展开更多
The purpose of this study was to evaluate the diagnostic performance of multiparametric ultrasound(mpUS;grayscale US,color Doppler US,strain elastography,and contrast-enhanced US)in the assessment of testicular lesion...The purpose of this study was to evaluate the diagnostic performance of multiparametric ultrasound(mpUS;grayscale US,color Doppler US,strain elastography,and contrast-enhanced US)in the assessment of testicular lesions with negative tumoral markers.MpUS imaging data,patient age,serum tumor markers,scrotal pain,cryptorchidism,and related clinical information were retrospectively collected for patients who underwent mpUS examination between January 2013 and December 2019.Histologic results or follow-up examinations were used as the reference standard.In total,83 lesions from 79 patients were included in the analysis.Fifty-six patients were finally diagnosed with benign tumors,and 23 patients were ultimately diagnosed with malignant tumors.Chi-square tests or Fisher's exact tests were used to assess the difference between the two groups.Stepwise multivariate logistic regression analysis showed that lesion diameter(odds ratio[OR]=1.072,P=0.005),vascularization on color Doppler US(OR=4.066,P=0.001),and hyperenhancement during the early phase(OR=6.465,P=0.047)were significant independent risk factors for malignancy;however,when compared with neoplastic lesions,pain(OR=0.136,P<0.001),absence of vascularization on color Doppler US(OR=1.680,P=0.042),and nonenhancement during the late phase(OR=3.461,P=0.031)were strongly associated with nonneoplastic lesions.MpUS features are useful for differentiating testicular lesions with negative tumoral markers and improving the preoperative diagnosis,which may avoid inappropriate radical orchiectomy.展开更多
Prostate-targeted biopsy is usually the preferred method over systematic biopsy because it can effectively detect prostate cancer using only a few puncture cores with fewer complications.With the development of ultras...Prostate-targeted biopsy is usually the preferred method over systematic biopsy because it can effectively detect prostate cancer using only a few puncture cores with fewer complications.With the development of ultrasound,it has gained multimodal technological upgrades,such as the emergence of contrast-enhanced ultrasound,ultrasound elastography,and three-dimensional ultrasonography.Moreover,multimodal ultrasound has played an increasingly significant role in prostate-targeted biopsies.展开更多
A new modeling method has been developed by combining industrial data and metallurgical mechanisms.This method utilizes a series of models to predict the mechanical properties for microalloyed steels with high reliabi...A new modeling method has been developed by combining industrial data and metallurgical mechanisms.This method utilizes a series of models to predict the mechanical properties for microalloyed steels with high reliability and strong generalization.Specifically,the modeling process includes determining the influencing factors,cleaning the actual data,building sub-models for each single factor and for the interactions between the factors,verifying the reproducibility of the sub-models,and building the whole model.The effects of alloying elements(such as C,Si,Nb,and V),precipitation processes of microalloying elements,and processing parameters(such as reheating temperature and coiling temperature)are quantitatively involved in the models.In addition,the obtained models can quantitatively describe the effect of each factor on the mechanical properties,which is impossible by using traditional modeling methods.A practical modeling case is introduced,and the influencing mechanisms of the factors on the mechanical properties are analyzed.The results show that the prediction errors for the tensile strength and yield strength are 2.54%and 3.34%,respectively,which exhibits the advantages of high precision and strong adaptability of the model used to design and develop new steel grades,reduce the number of physical tests,and reduce the development cost of new products.展开更多
Simultaneous thermal analysis（STA） was used to investigate the effects of silicon content on the oxidation kinetics of silicon-containing steels under an atmosphere and heating procedures similar to those used in in...Simultaneous thermal analysis（STA） was used to investigate the effects of silicon content on the oxidation kinetics of silicon-containing steels under an atmosphere and heating procedures similar to those used in industrial reheating furnaces for the production of hot-rolled strips. Our results show that when the heating temperature was greater than the melting point of Fe2SiO4, the oxidation rates of steels with different silicon contents were the same; the total mass gain decreased with increasing silicon content, whereas it increased with increasing oxygen content. The oxidation rates for steels with different silicon contents were constant with respect to time under isothermal conditions. In addition, the starting oxidation temperature, the intense oxidation temperature, and the finishing oxidation temperature increased with increasing silicon content; the intense oxidation temperature had no correlation with the melting of Fe2SiO4. Moreover, the silicon distributed in two forms： as Fe2SiO4 at the interface between the innermost layer of oxide scale and the iron matrix, and as particles containing silicon in grains and grain boundaries in the iron matrix.展开更多
The purpose of this study was to explore transrectal ultrasound(TRUS)findings of prostate cancer(PCa)guided by multiparametric magnetic resonance imaging(mpMRI)and to improve the Prostate Imaging Reporting and Data Sy...The purpose of this study was to explore transrectal ultrasound(TRUS)findings of prostate cancer(PCa)guided by multiparametric magnetic resonance imaging(mpMRI)and to improve the Prostate Imaging Reporting and Data System(PI-RADS)system for avoiding unnecessary mpMRI-guided targeted biopsy(TB).From January 2018 to October 2019,fusion mpMRI and TRUS-guided biopsies were performed in 162 consecutive patients.The study included 188 suspicious lesions on mpMRI in 156 patients,all of whom underwent mpMRI-TRUS fusion imaging-guided TB and 12-core transperineal systematic biopsy(SB).Univariate analyses were performed to investigate the relationship between TRUS features and PCa.Then,logistic regression analysis with generalized estimating equations was performed to determine the independent predictors of PCa and obtain the fitted probability of PCa.The detection rates of PCa based on TB alone,SB alone,and combined SB and TB were 55.9%(105 of 188),52.6%(82 of 156),and 62.8%(98 of 156),respectively.The significant predictors of PCa on TRUS were hypoechogenicity(odds ratio[OR]:9.595,P=0.002),taller-than-wide shape(OR:3.539,P=0.022),asymmetric vascular structures(OR:3.728,P=0.031),close proximity to capsule(OR:3.473,P=0.040),and irregular margins(OR:3.843,P=0.041).We propose subgrouping PI-RADS score 3 into categories 3a,3b,3c,and 3d based on different numbers of TRUS predictors,as the creation of PI-RADS 3a(no suspicious ultrasound features)could avoid 16.7%of mpMRI-guided TBs.Risk stratification of PCa with mpMRI-TRUS fusion imaging-directed ultrasound features could avoid unnecessary mpMRI-TBs.展开更多
基金supported by the National Natural Science Foundation of China(Nos.52274392 and 52104381)Natural Science Foundation of Hubei Province(No.2023AFB023)Knowledge Innovation Program of Wuhan-Basi Research(No.2023010201010133).
文摘The integration of boronizing and austempering termed boro-austempering treatment is a new processing route for preparing high strength bainitic steel with high surface hardness and high corrosion resistance.The microstructure and properties of a medium-carbon bainitic steel prepared by boro-austempering treatment were characterized and analyzed.The results show that a single Fe_(2)B layer on bainite substrate was obtained with surface hardness of~1400 HV,and the critical load for adhesive failure of borided layer reached 73.6 N.The silicon-rich α-Fe phase in transition zone was clarified as ferrite,which was formed at the beginning stage of cooling process from boronizing to low-temperature bainite transformation.Moreover,the relative potential differences between Fe_(2)B and bainite matrix,and ferrite and bainite matrix were 75 and 92 mV,respectively,with bainite matrix acting as active anode,indicating that the corrosion resistances of Fe2B and ferrite were better than that of bainite.
基金support received from the National Natural Science Foundation of China(52274305,U20A20277)the Hubei Province key research and development project(2022BAA021).
文摘High-temperature confocal laser scanning microscopy(HT-CLSM)is considered as a powerful tool for in situ observation of the phase transformation of steels at elevated temperatures.It breaks the limitation that conventional approaches on this aspect can only post-mortem the microstructure at room temperature.The working principle and major functions of HT-CLSM in initial are introduced and the utilization in details with HT-CLSM is summarized,including the behaviors of melting-solidifying,austenite reversion,as well as the austenite decomposition(formation of Widmanstätten,pearlite,acicular ferrite,bainite and martensite)in steels.Moreover,a serie of HT-CLSM images are used to explore the growth kinetic of phase at elevated temperatures with additional theoretical calculation models.Finally,the in situ HT-CLSM observations of phase transformation,combined with post-mortem electron backscatter diffraction analysis,is also summarized to elucidate the crystallographic evolution.
基金supports from National Natural Science Foundation of China(No.U20A20270)China Postdoctoral Science Foundation(No.2022M722486).
文摘The effects of austenite grain size on the deformed microstructure and mechanical properties of an Fe-20Mn-6Al-0.6C-0.15Si(wt.%)low-density steel were investigated.The microstructure of the experimental steel after solution treatment was single austenitic phase.The austenite grain size increased with solution temperature and time.A model was established to show the relationship between temperature,time and austenite grain size for the experimental steel.In addition,as the solution temperature increased,the strength decreased,while the elongation first increased and then decreased.This decrease in elongation after solution treatment at 1100℃ for 90 min is contributed to the over-coarse austenite grains.However,after solution treatment at 900℃ for 90 min,the strength-elongation product reached the highest value of 44.4 GPa%.As the austenite grain size increased,the intensity of<111>//tensile direction fiber decreased.This was accompanied by a decrease in dislocation density,resulting in a lower fraction of low-angle grain boundaries and a lower work hardening rate.Therefore,the austenite grain size has a critical influence on the mechanical properties of the low-density steels.Coarser grains lead to a lower yield strength due to the Hall-Petch effect and a lower tensile strength because of lower dislocation strengthening.
基金financial support from the National Natural Science Foundation of China (Nos. 21801087 and 22201089)。
文摘An enantioselective catalytic method for the direct [4 + 1] annulation of yne–allylic acetates with pyrazolones has been realized by a copper-catalyzed remote strategy. A variety of enantioenriched spiropyrazolones are rapidly accessed in high yields with moderate to good enantiocontrol. The facile follow-up transformations highlight its potential utility in the synthesis of diverse spiropyrazolones building blocks.
基金financially supported by the National Natural Science Foundation of China (No. 51674071)
文摘The formation mechanism of acicular ferrite and its microstructural characteristics in 430 ferrite stainless steel with TiC additions were studied by theory and experiment.Using an"edge?to?edge matching"model,a 5.25 mismatch between TiC(FCC structure)and ferritic stainless steel(BCC structure)was identified,which met the mismatch requirement for the heterogeneous nucleation of 430 ferritic stainless steel.TiC was found to be an effective nucleation site for the formation of acicular ferrite in a smelting experiment,as analyzed by metallographic examination,Image-Pro Plus 6.0 analysis software,and SEM–EDS.Furthermore,small inclusions in the size of 2–4?m increased the probability of acicular ferrite nucleation,and the secondary acicular ferrite would grow sympathetically from the initial acicular ferrite to produce multi-dimensional acicular ferrites.Moreover,the addition of Ti C can increase the average microstrain and dislocation density of 430 ferrite stainless steel,as calculated by Williamson-Hall(WH)method,which could play some role in strengthening the dislocation.
基金financially supported by the National Natural Science Foundation of China(No.51274154)the National High-Tech Research and Development Program of China(No.2012AA03A504)+1 种基金the State Key Laboratory of Development and Application Technology of Automotive Steels(Baosteel Group)the Key Project of Hubei Education Committee,China(No.20121101)
文摘The growth rates of bainite plates in an Fe-C-Mn-Si superbainitie steel were investigated by in situ observation. The lengthening rates of ferrite bainite during both cooling and isothermal holding processes were observed and the growth rates of bainite plates nucleating at grain boundaries, within grains and on preformed bainite were measured. It is indicated that the lengthening rates of bainite plates during the cooling and isothermal processes were different, and that the growth rates of bainite plates nucleating at different types of sites also demon- strated diversity. The bainite plates initiating at [vain boundaries during cooling grew the fastest, while the plates nucleating on preformed bainite did the slowest. However, the growth rate of the bainite plates nucleating at grain boundaries during isothermal transformation de- creased the most, whereas the bainite plates initiating within grains grew the fastest. In addition, the growth rate of ferrite bainite in the study supported the diffusion transformation mechanism of bainite from the viewooint of ~rowth rate.
基金the National Natural Science Foundation of China(No.51274154)the National High-Tech Research and Development Program of China(No.2012AA03A504)+1 种基金the State Key Laboratory of Development and Application Technology of Automo-tive Steels(Baosteel Group)the Key Project of Hubei Education Committee(No.D20121101)
文摘In situ observations of austenite grain growth in Fe-C-Mn-Si super bainitic steel were conducted on a high-temperature laser scanning confocal microscope during continuous heating and subsequent isothermal holding at 850, 1000, and 1100℃ for 30 min. A grain growth model was proposed based on experimental results. It is indicated that the austenite grain size increases with austenitizing temperature and holding time. When the austenitizing temperature is above 1100℃, the austenite grains grow rapidly, and abnormal austenite grains occur. In addition, the effect of heating rate on austenite grain growth was investigated, and the relation between austenite grains and bainite morphology after bainitic transformations was also discussed.
基金the Minerals Research Institute of Western Australia(M495)the computation resources provided by the Pawsey Supercomputing Centre with funding from the Australian Government and the Government of Western Australia.
文摘In 2012,the International Agency for Research on Cancer(IARC)classified diesel particulate matter(DPM)as a carcinogen to human.With the increased usage of diesel equipment in underground mines,miners have a high risk of over-exposure to DPM,which has drawn many concerns from the public.This study used computational fluid dynamics(CFD)to analyse the DPM dispersion and concentration distribution characteristics in an underground development face based on an onsite experiment.The DPM emitted from a moving loader under a forcing auxiliary ventilation system was simulated.The motion of the load-haul-dump(LHD)in the tunnel was represented by a dynamic mesh method.The species transport approach was applied to study the DPM behaviours.High DPM concentration zones were then identified based on the simulation results.The results could provide guidelines for work practices and be helpful to an optimum auxiliary ventilation design to reduce underground miner exposure.
基金The authors gratefully acknowledge the financial supports from National Natural Science Foundation of China (Nos. 51274154 and 51704217)Major Projects of Technological Innovation in Hubei (No. 2017AAA116)the Special Fund of Wuhan University of Science and Technology for Master Students' Short-Term Studying Abroad, and the State Scholarship Fund of China Scholarship Council.
文摘The effects of aluminum addition on bainite transformation and properties of carbide-free bainitic steels containing 0.22 wt.% carbon were investigated by two different types of heat treatment processes: continuous cooling process (CCP) and isothermal transformation process (ITP). The results indicate that for the CCP treatment, Al addition significantly promoted the ferrite and bainite transformation;however, it did not significantly increase the product of tensile strength and total elongation (PSE). For the ITP treatment, Al addition significantly promoted the kinetics of bainite transformation, and thus, more bainite was formed with Al addition;however, it was found that Al addition resulted in a decrease in tensile strength and an increase in elongation of the tested bainitic steels. Moreover, the effects of Al addition on comprehensive property were profoundly dependent on austempering temperatures. When the austempering temperature was higher (430℃), PSE significantly increased with Al addition, whereas it decreased at the lower austempering temperature (400℃). Therefore, it can be concluded that the effects of Al on properties of bainitic steels were more significant at higher austempering temperatures.
文摘Exposure to mining-induced particulate matter(PM)including coal dust and diesel particulate matter(DPM)causes severe respirat-ory diseases such as coal workers’pneumoconiosis(CWP)and lung cancer.Limited spatiotemporal resolution of current PM monitors causes miners to be exposed to unknown PM concentrations,with increased overexposure risk.Low-cost PM sensors offer a potential solution to this challenge with their capability in characterizing PM concentrations with high spatiotemporal resolution.However,their application in underground mines has not been explored.With the aim of examining the potential application of low-cost sensors in underground mines,a critical review of the present status of PM sensor research is conducted.The working principles of present PM monitors and low-cost sensors are com-pared.Sensor error sources are identified,and comprehensive calibration processes are presented to correct them.Evaluation protocols are pro-posed to evaluate sensor performance prior to deployment,and the potential application of low-cost sensors is discussed.
基金This work was supported in part by the National Natural Science Foundation of China(grant No.81725008 and No.81801700)Shanghai Municipal Health Commission(grant No.2019LJ21 and No.SHSLCZDZK03502)+2 种基金Science and Technology Commission of Shanghai Municipality(grant No.19DZ2251100)Fundamental Research Funds for the Central Universities(ZD-11-202151)Scientific Research and Development Fund of Zhongshan Hospital of Fudan University(grant No.2022ZSQD07).
文摘The purpose of this study was to analyze the value of transrectal shear-wave elastography(SWE)in combination with multivariable tools for predicting adverse pathological features before radical prostatectomy(RP).Preoperative clinicopathological variables,multiparametric magnetic resonance imaging(mp-MRI)manifestations,and the maximum elastic value of the prostate(Emax)on SWE were retrospectively collected.The accuracy of SWE for predicting adverse pathological features was evaluated based on postoperative pathology,and parameters with statistical significance were selected.The diagnostic performance of various models,including preoperative clinicopathological variables(model 1),preoperative clinicopathological variables+mp-MRI(model 2),and preoperative clinicopathological variables+mp-MRI+SWE(model 3),was evaluated with area under the receiver operator characteristic curve(AUC)analysis.Emax was significantly higher in prostate cancer with extracapsular extension(ECE)or seminal vesicle invasion(SVI)with both P<0.001.The optimal cutoff Emax values for ECE and SVI were 60.45 kPa and 81.55 kPa,respectively.Inclusion of mp-MRI and SWE improved discrimination by clinical models for ECE(model 2 vs model 1,P=0.031;model 3 vs model 1,P=0.002;model 3 vs model 2,P=0.018)and SVI(model 2 vs model 1,P=0.147;model 3 vs model 1,P=0.037;model 3 vs model 2,P=0.134).SWE is valuable for identifying patients at high risk of adverse pathology.
基金supported in part by the National Natural Science Foundation of China (No.81801700)the Fundamental Research Funds for the Central Universities (No.ZD-11-202151)+2 种基金the Shanghai Municipal Health Commission (No.2019LJ21 and No.SHSLCZDZK03502)the Science and Technology Commission of Shanghai Municipality (No.19DZ2251100)the Scientific Research and Development Fund of Zhongshan Hospital of Fudan University (No.2022ZSQD07).
文摘The purpose of this study was to evaluate the diagnostic performance of multiparametric ultrasound(mpUS;grayscale US,color Doppler US,strain elastography,and contrast-enhanced US)in the assessment of testicular lesions with negative tumoral markers.MpUS imaging data,patient age,serum tumor markers,scrotal pain,cryptorchidism,and related clinical information were retrospectively collected for patients who underwent mpUS examination between January 2013 and December 2019.Histologic results or follow-up examinations were used as the reference standard.In total,83 lesions from 79 patients were included in the analysis.Fifty-six patients were finally diagnosed with benign tumors,and 23 patients were ultimately diagnosed with malignant tumors.Chi-square tests or Fisher's exact tests were used to assess the difference between the two groups.Stepwise multivariate logistic regression analysis showed that lesion diameter(odds ratio[OR]=1.072,P=0.005),vascularization on color Doppler US(OR=4.066,P=0.001),and hyperenhancement during the early phase(OR=6.465,P=0.047)were significant independent risk factors for malignancy;however,when compared with neoplastic lesions,pain(OR=0.136,P<0.001),absence of vascularization on color Doppler US(OR=1.680,P=0.042),and nonenhancement during the late phase(OR=3.461,P=0.031)were strongly associated with nonneoplastic lesions.MpUS features are useful for differentiating testicular lesions with negative tumoral markers and improving the preoperative diagnosis,which may avoid inappropriate radical orchiectomy.
文摘Prostate-targeted biopsy is usually the preferred method over systematic biopsy because it can effectively detect prostate cancer using only a few puncture cores with fewer complications.With the development of ultrasound,it has gained multimodal technological upgrades,such as the emergence of contrast-enhanced ultrasound,ultrasound elastography,and three-dimensional ultrasonography.Moreover,multimodal ultrasound has played an increasingly significant role in prostate-targeted biopsies.
基金National Natural Science Foundation of China(51774219)Youth Science and Technology Program of Wuhan(2016070204010099).
文摘A new modeling method has been developed by combining industrial data and metallurgical mechanisms.This method utilizes a series of models to predict the mechanical properties for microalloyed steels with high reliability and strong generalization.Specifically,the modeling process includes determining the influencing factors,cleaning the actual data,building sub-models for each single factor and for the interactions between the factors,verifying the reproducibility of the sub-models,and building the whole model.The effects of alloying elements(such as C,Si,Nb,and V),precipitation processes of microalloying elements,and processing parameters(such as reheating temperature and coiling temperature)are quantitatively involved in the models.In addition,the obtained models can quantitatively describe the effect of each factor on the mechanical properties,which is impossible by using traditional modeling methods.A practical modeling case is introduced,and the influencing mechanisms of the factors on the mechanical properties are analyzed.The results show that the prediction errors for the tensile strength and yield strength are 2.54%and 3.34%,respectively,which exhibits the advantages of high precision and strong adaptability of the model used to design and develop new steel grades,reduce the number of physical tests,and reduce the development cost of new products.
基金the financial support from the National Natural Science Foundation of China(NSFC)(No.51274154)the State Key Laboratory of Development and Application Technology of Automotive Steels(Baosteel Group)
文摘Simultaneous thermal analysis（STA） was used to investigate the effects of silicon content on the oxidation kinetics of silicon-containing steels under an atmosphere and heating procedures similar to those used in industrial reheating furnaces for the production of hot-rolled strips. Our results show that when the heating temperature was greater than the melting point of Fe2SiO4, the oxidation rates of steels with different silicon contents were the same; the total mass gain decreased with increasing silicon content, whereas it increased with increasing oxygen content. The oxidation rates for steels with different silicon contents were constant with respect to time under isothermal conditions. In addition, the starting oxidation temperature, the intense oxidation temperature, and the finishing oxidation temperature increased with increasing silicon content; the intense oxidation temperature had no correlation with the melting of Fe2SiO4. Moreover, the silicon distributed in two forms： as Fe2SiO4 at the interface between the innermost layer of oxide scale and the iron matrix, and as particles containing silicon in grains and grain boundaries in the iron matrix.
基金This work was supported in part by the National Natural Science Foundation of China(No.81671695,81725008,81801700 and 81927801)Fundamental Research Funds for the Central Universities(No.22120190213)+1 种基金Shanghai Municipal Health Commission(No.2019LJ21 and SHSLCZDZK03502)the Science and Technology Commission of Shanghai Municipality(No.19DZ2251100 and 19441903200).
文摘The purpose of this study was to explore transrectal ultrasound(TRUS)findings of prostate cancer(PCa)guided by multiparametric magnetic resonance imaging(mpMRI)and to improve the Prostate Imaging Reporting and Data System(PI-RADS)system for avoiding unnecessary mpMRI-guided targeted biopsy(TB).From January 2018 to October 2019,fusion mpMRI and TRUS-guided biopsies were performed in 162 consecutive patients.The study included 188 suspicious lesions on mpMRI in 156 patients,all of whom underwent mpMRI-TRUS fusion imaging-guided TB and 12-core transperineal systematic biopsy(SB).Univariate analyses were performed to investigate the relationship between TRUS features and PCa.Then,logistic regression analysis with generalized estimating equations was performed to determine the independent predictors of PCa and obtain the fitted probability of PCa.The detection rates of PCa based on TB alone,SB alone,and combined SB and TB were 55.9%(105 of 188),52.6%(82 of 156),and 62.8%(98 of 156),respectively.The significant predictors of PCa on TRUS were hypoechogenicity(odds ratio[OR]:9.595,P=0.002),taller-than-wide shape(OR:3.539,P=0.022),asymmetric vascular structures(OR:3.728,P=0.031),close proximity to capsule(OR:3.473,P=0.040),and irregular margins(OR:3.843,P=0.041).We propose subgrouping PI-RADS score 3 into categories 3a,3b,3c,and 3d based on different numbers of TRUS predictors,as the creation of PI-RADS 3a(no suspicious ultrasound features)could avoid 16.7%of mpMRI-guided TBs.Risk stratification of PCa with mpMRI-TRUS fusion imaging-directed ultrasound features could avoid unnecessary mpMRI-TBs.
