With the increasing number of vehicles,manual security inspections are becoming more laborious at road checkpoints.To address it,a specialized Road Checkpoints Robot(RCRo)system is proposed,incorporated with enhanced ...With the increasing number of vehicles,manual security inspections are becoming more laborious at road checkpoints.To address it,a specialized Road Checkpoints Robot(RCRo)system is proposed,incorporated with enhanced You Only Look Once(YOLO)and a 6-degree-of-freedom(DOF)manipulator,for autonomous identity verification and vehicle inspection.The modified YOLO is characterized by large objects’sensitivity and faster detection speed,named“LF-YOLO”.The better sensitivity of large objects and the faster detection speed are achieved by means of the Dense module-based backbone network connecting two-scale detecting network,for object detection tasks,along with optimized anchor boxes and improved loss function.During the manipulator motion,Octree-aided motion control scheme is adopted for collision-free motion through Robot Operating System(ROS).The proposed LF-YOLO which utilizes continuous optimization strategy and residual technique provides a promising detector design,which has been found to be more effective during actual object detection,in terms of decreased average detection time by 68.25%and 60.60%,and increased average Intersection over Union(Io U)by 20.74%and6.79%compared to YOLOv3 and YOLOv4 through experiments.The comprehensive functional tests of RCRo system demonstrate the feasibility and competency of the multiple unmanned inspections in practice.展开更多
AIM:To evaluate whether the application of sorafenib during the peri-operative period of liver transplantation improves prognosis in liver cancer patients.METHODS:We searched Pub Med,EMBASE and MEDLINE for eligible ar...AIM:To evaluate whether the application of sorafenib during the peri-operative period of liver transplantation improves prognosis in liver cancer patients.METHODS:We searched Pub Med,EMBASE and MEDLINE for eligible articles.A total of 4 studieswere found that fulfilled the previously agreed-upon standards.We then performed a systematic review and meta-analysis on the enrolled trials that met the inclusion criteria.RESULTS:Out of the 104 studies identified in the database,82 were not clinical experiments,and 18 did not fit the inclusion standards.Among the remaining 4 articles,only 1 was related to the preoperative use of sorafenib,whereas the other 3 were related to its postoperative use.As the heterogeneity among the 4 studies was high,with an I2 of 86%,a randomized effect model was applied to pool the data.The application of sorafenib before liver transplantation had a hazard ratio(HR) of 3.29 with a 95% confidence interval(CI) of 0.33-32.56.The use of sorafenib after liver transplantation had an HR of 1.44(95%CI:0.27-7.71).The overall pooled HR was 1.68(95%CI:0.41-6.91).CONCLUSION:The results showed that the use of sorafenib during the peri-operative period of liver transplantation did not improve patient survival significantly.In fact,sorafenib could even lead to a worse prognosis,as its use may increase the hazard of poor survival.展开更多
The magnetic properties of highly grain-oriented electrical steel vary along different directions. In order to investigate these properties, standard Epstein samples were cut at different angles to the rolling directi...The magnetic properties of highly grain-oriented electrical steel vary along different directions. In order to investigate these properties, standard Epstein samples were cut at different angles to the rolling direction. The hard magnetization direction was found at an angle of 60° to the rolling direction. To compare the measured and fitting curves, when the magnetic field intensity is higher than 7000 A/m, it is appropriate to simulate the relation of magnetic permeability and magnetization angle using the conventional elliptical model. When the magnetic field intensity is less than 3000 A/m, parabolic fitting models should be used; but when the magnetic field intensity is between 3000 and 7000 A/m, hybrid models with high accuracy, as proposed in this paper, should be applied. Piecewise relation models of magnetic permeability and magnetization angle are significant for improving the accuracy of electromagnetic engineering calculations of electrical steel, and these new models could be applied in further industrial applications.展开更多
Diabetes is a chronic disease characterized by hyperglycemia,of which type 2 diabetes mellitus(T2DM)accounts for about 95%[1].In addition,the prevalence of T2DM is still rising,seriously threatening human health.As th...Diabetes is a chronic disease characterized by hyperglycemia,of which type 2 diabetes mellitus(T2DM)accounts for about 95%[1].In addition,the prevalence of T2DM is still rising,seriously threatening human health.As the mechanism of T2DM is not fully understood,most of the current drugs for the treatment of T2DM focus on lowering blood glucose without solving its underlying problem.This review discusses the application of ginseng-jujube-licorice group in T2DM based on theory of traditional Chinese medicine and research of modern pharmacology,in order to provide a reference for the development of new drugs and future research.展开更多
The effect of ball scribing on iron loss of conventional grain-oriented ( CGO) and high-permeability grain-oriented ( HGO) electrical steel was investigated. In this paper,ball scribing was achieved by self- designed ...The effect of ball scribing on iron loss of conventional grain-oriented ( CGO) and high-permeability grain-oriented ( HGO) electrical steel was investigated. In this paper,ball scribing was achieved by self- designed ball scribing instrument and a computer-controlled system capable of providing high accuracy and automatic measurements was developed for the magnetisation and measurement at high and low flux densities. The results showed that after ball scribing,iron loss of two types of steel ( C711 and H668 ) apparently decreases ( 5. 5% and 8. 2% respectively after 16mm scribing at 1. 2T) ,and at high and low flux densities, CGO and HGO electrical steel performs differently. Through the formation and development of free magnetic poles and secondary magnetic domains due to compressive stress,primary magnetic domain spacing of grain- oriented electrical steel becomes smaller,which reflects as a reduction of iron loss in the macroscopic magnetic properties. Through iron loss formula derivation,the effect of domain refinement on grain-oriented electrical steel was also interpreted.展开更多
BACKGROUND The corona virus disease 2019(COVID-19)has been a pandemic for more than one year and estimated to affect the whole world in the near future.CASE SUMMARY Here we reported that one COVID-19 patient with vesi...BACKGROUND The corona virus disease 2019(COVID-19)has been a pandemic for more than one year and estimated to affect the whole world in the near future.CASE SUMMARY Here we reported that one COVID-19 patient with vesicles was treated by bullectomy.The patient’s perioperative laboratory tests were analyzed.The pathological findings of bullectomy were described and compared with those of common bulla cases.CONCLUSION This patient with vesicles underwent bullectomy and had a poor prognosis.He showed diffuse alveolar damage and extensive necrosis in bullectomy specimen.We hope our report will be of interest for clinicians who will treat COVID-19 patients in the future.展开更多
Understanding the fracture behavior of fused silica in contact sliding is important to the fabrication of damage-free optics.This study develops an analytical method to characterize the stress field in fused silica un...Understanding the fracture behavior of fused silica in contact sliding is important to the fabrication of damage-free optics.This study develops an analytical method to characterize the stress field in fused silica under contact sliding by extending the embedded center of dilation(ECD)model and considering the depth of yield region.The effects of densification on the stress fields were considered by scratch volume analysis and finite element analysis.Key mechanisms,such as crack initiation and morphology evolution were comprehensively investigated by analyzing the predicted stress fields and principal stress trajectories.The predictions were validated by Berkovich scratching experiment.It was found that partial conical,median and lateral cracks could emerge in the loading stage of the contact sliding,but radial and lateral cracks could be initiated during unloading.It was also found that the partial conical crack had the lowest initiation load.The intersection of long lateral cracks makes the material removal greater.展开更多
The thermal scratch significantly influences the surface quality of the cold rolled stainless steel strip. In or der to establish a precise mathematical model of oil film thickness in deformation zone, the lubrication...The thermal scratch significantly influences the surface quality of the cold rolled stainless steel strip. In or der to establish a precise mathematical model of oil film thickness in deformation zone, the lubrication in cold rolling process of B443NT stainless steel strip was studied in the laboratory. According to the principle of statistics, a math- ematical model of critical oil film thickness in deformation zone for thermal scratch was built, with fitting and regres- sion analytical method, and then based on temperature comparison method, the criterion for deciding thermal scratch defect was put forward. Storing and calling data through SQI. Server 2005, a software on thermal scratch control was developed in the Microsoft Visual Studio 2008 environment by MFC technique for stainless steel in tandem cold roll- ing, and then it was used into the practical production. Statistical results demonstrated that the hit rate of thermal scratch arrives at 91.47%, the occurrence rate of thermal scratch is decreased by 87.81%, and rolling speed is in- creased by 7.3%. The developed software is of significance to the control of products quality of stainless steel strips, and the analysis and solution to the problem of thermal scratch defects in tandem cold rolling.展开更多
The thermal scratch significantly influences the surface quality of the stainless steel in cold strip rolling. The thermal scratch has a close relation to the rolling parameters, the rolls surface and the emulsions us...The thermal scratch significantly influences the surface quality of the stainless steel in cold strip rolling. The thermal scratch has a close relation to the rolling parameters, the rolls surface and the emulsions used in rolling. In order to explain the thermal scratch on the strip surface, the cold roiling process of SUS430 stainless steel strip was investigated in the laboratory. The thermal scratch defect occurs frequently in the second rolling pass （maximum reduction in height is 32.3 ~）, especially on the lower surface of strips. When concentration and temperature of the emulsion are the same, the thermal scratch on the surface o{ the strip is aggravated with increasing the roll surface roughness. With the same roll surface roughness and emulsion concentration, the thermal scratch is obviously more severe at an emulsion temperature of 63 ℃ than 55 ℃. With the same roll surface roughness and emulsion tempera- ture, the thermal scratch is distinctly weaker at the emulsion concentration of 6 % than that of 3 %.展开更多
Background：A single drilled tunnel from the lateral mastoid cortex to the cochlea via the facial recess is essential for minimally invasive cochlear implant surgery.This study aimed to explore the safety profile of t...Background：A single drilled tunnel from the lateral mastoid cortex to the cochlea via the facial recess is essential for minimally invasive cochlear implant surgery.This study aimed to explore the safety profile of this kind of new image-guided and bi-planar device-assisted surgery procedure in vitro.Methods：Image-guided minimally invasive cochlear implantations were performed on eight cadaveric temporal bone specimens.The main procedures were：（1） temporal bone specimens were prepared for surgery and fiducial markers were registered.（2） computed tomography （CT） scans were performed for future reference.（3） CT scan images were processed and drill path was planned to minimize cochlear damage.（4） bi-planar device-assisted drilling was performed on the specimens using the registration.（5） surgical safety was evaluated by calculating the deviation between the drill and the planned paths,and by measuring the closest distance between the drilled path and critical anatomic structures.Results：Eight cases were operated successfully to the basal turn of the cochlear with intact facial nerves （FNs）.The deviations from target points and entrance points were 0.86 mm （0.68-1.00 mm） and 0.44 mm （0.30-0.96 mm）,respectively.The angular error between the planned and the drilled trajectory was 1.74° （1.26-2.41°）.The mean distance from the edge of the drilled path to the FN and to the external canal was 0.60 mm （0.35-0.83 mm） and 1.60 mm （1.30-2.05 mm）,respectively.In five specimens,the chorda tympani nerves were well preserved.In all cases,no injury happened to auditory ossicles.Conclusions：This exploratory study demonstrated the safety of the newly developed image-guided minimally invasive cochlear implantation assisted by the bi-planar device and established the operational procedures.Further,more in vitro experiments are needed to improve the system operation and its safety.展开更多
Magnetic shielding of grain-oriented silicon steel was investigated. Ball scribing with spacing of 2 to 16 mm was performed at peak flux densities of 8.0 mT to 1.3 T. Magnetic shielding efficiency was calculated, incl...Magnetic shielding of grain-oriented silicon steel was investigated. Ball scribing with spacing of 2 to 16 mm was performed at peak flux densities of 8.0 mT to 1.3 T. Magnetic shielding efficiency was calculated, including absorption, reflection and inner multi-reflection shielding efficiencies. Magnetic shielding efficiency （MSE） increase ratios after different scribing spacing were compared, and thickness requirement to achieve absorption shielding of 50 dB was also calculated. The results show that magnetic shielding efficiencies of C711 and H668 silicon steels increase by 4.79 and 3.15 dB respectively after scribing of 16 mm. Before scribing, shielding efficiency of H668 steel was higher than that of C711 steel, while after scribing, both absorption and shielding efficiency gaps were largely abridged between C711 and H668 steels. Plate thickness of C711 steel could be reduced from 3.18 mm without scribing to 2. 20 mm after scribing of 16 mm. There is no apparent thickness reduction at lower flux densities; while the peak flux density is above 0.3 T, the shielding effect becomes apparent, and the thickness could be reduced from 2.28 mm without scribing to 1.70 mm with scribing spacing of 16 ram. Magnetizing process and its effect on variation of magnetic shielding were also analyzed.展开更多
Action recognition and localization in untrimmed videos is important for many applications and have attracted a lot of attention. Since full supervision with frame-level annotation places an overwhelming burden on man...Action recognition and localization in untrimmed videos is important for many applications and have attracted a lot of attention. Since full supervision with frame-level annotation places an overwhelming burden on manual labeling effort, learning with weak video-level supervision becomes a potential solution. In this paper, we propose a novel weakly supervised framework to recognize actions and locate the corresponding frames in untrimmed videos simultaneously. Considering that there are abundant trimmed videos publicly available and well-segmented with semantic descriptions, the instructive knowledge learned on trimmed videos can be fully leveraged to analyze untrimmed videos. We present an effective knowledge transfer strategy based on inter-class semantic relevance. We also take advantage of the self-attention mechanism to obtain a compact video representation, such that the influence of background frames can be effectively eliminated. A learning architecture is designed with twin networks for trimmed and untrimmed videos, to facilitate transferable self-attentive representation learning. Extensive experiments are conducted on three untrimmed benchmark datasets (i.e., THUMOS14, ActivityNet1.3, and MEXaction2), and the experimental results clearly corroborate the efficacy of our method. It is especially encouraging to see that the proposed weakly supervised method even achieves comparable results to some fully supervised methods.展开更多
Microstructural evolution and mechanical properties of cryogenic rolled Fe-36Ni steel were investigated. The annealed Fe-36Ni steel was rolled at cryogenic temperature（ 123-173 K） with 20%- 90% rolling reduction in ...Microstructural evolution and mechanical properties of cryogenic rolled Fe-36Ni steel were investigated. The annealed Fe-36Ni steel was rolled at cryogenic temperature（ 123-173 K） with 20%- 90% rolling reduction in thickness.The deformation process was accompanied by twinning at cryogenic temperature,and the mean thickness of deformation twins was about 200 nm with 20% rolling reduction. When the rolling reduction was above 40%,twinning was suppressed due to the stress concentration in the tested steel. Deformation microstructure of Fe-36Ni steel consisted of both twin boundaries and dislocations by cryogenic rolling（ CR）,while it only contained dislocations after rolling at room temperature（ RT）. The tensile strength of Fe-36Ni steel was improved to 930 MPa after 90% reduction at cryogenic temperature,while the tensile strength after 90% reduction at RT was only 760 MPa. More dislocations could be produced as the nucleation sites of recrystallization during CR process.展开更多
Based on the rigid-plastic finite element method（FEM）, the shear stress field of deformation region for high manganese austenite steel during hot asymmetrical rolling process was analyzed. The influences of rolling ...Based on the rigid-plastic finite element method（FEM）, the shear stress field of deformation region for high manganese austenite steel during hot asymmetrical rolling process was analyzed. The influences of rolling parameters, such as the velocity ratio of upper to lower rolls, the initial temperature of workpiece and the reduction rate, on the shear deformation of three nodes in the upper, center and lower layers were discussed. As the rolling parameters change, distinct shear deformation appears in the upper and lower layers, but the shear deformation in the center layer appears only when the velocity ratio is more than 1.00, and the absolute value of the shear stress in this layer is changed with rolling parameters. A mathematical model which reflected the change of the maximal absolute shear stress for the center layer was established, by which the maximal absolute shear stress for the center layer can be easily calculated and the appropriate rolling technology can be designed.展开更多
Thermo-mechanical process and continuous cooling process were carried out on 20CrNi2MoV steel. Three cooling rates were implemented to optimize the mechanical properties. The microstructure evolution, precipitation be...Thermo-mechanical process and continuous cooling process were carried out on 20CrNi2MoV steel. Three cooling rates were implemented to optimize the mechanical properties. The microstructure evolution, precipitation behavior, and strengthening mechanisms were systematically investigated, and the fracture mechanisms were analyzed via combination of impact fracture morphologies and deflection-load curves. The experimental results indicate that the transformed microstructure of experimental steel is all complex consisting of granular bainitic ferrite and bainitic ferrite with dispersed martensite/austenite （M/A） constituents in the matrix at cooling rates of 13, 21, and 29 ℃/s. When the cooling rate increases, the grain of the steel is obviously refined. The sizes of the bainitic ferrite are 5.8, 4.7, and 3.1 μm under cooling rates of 13, 21, and 29 ℃/s, respectively. The refinement of the bainitic ferrite plays a dominant role in strength increasing and also contributes to high crack propagation energy. However, the morphologies of M/A constituents obtained under different cooling rates contribute to different crack initiation energies and then affect the impact property.展开更多
It is a common technical difficulty to improve the strength of low magnetic stainless steel plates on the premise of ensuring ductility,corrosion resistance,and low magnetism.In this paper,the chemical composition of ...It is a common technical difficulty to improve the strength of low magnetic stainless steel plates on the premise of ensuring ductility,corrosion resistance,and low magnetism.In this paper,the chemical composition of low magnetic stainless steels with excellent paramagnetic stabilities and corrosion resistances was formulated through composition design and calculation.Through the alloying of Nb,V,and N and the controlled hot rolling process,large numbers of uniformly distributed high-temperature second phase particles were formed in the steel plate,and low magnetic stainless steel 35 mm plate with yield strength,ultimate tensile strength and elongation of 407 MPa,739 MPa and 54%respectively were obtained.The main strengthening strategies of the steel were solid solution strengthening and precipitation strengthening.The precipitation law and types of the high-temperature second phase in the steel were explored.The micro structure of the steel plate was characterized by scanning electron microscope,electron probe microanalysis,and transmission electron microscope.The magnetic properties of the steel plate were tested by a vibrating sample magnetometer.The relative magnetic permeability of the hot rolled plate was 1.0063 which met the requirement of low magnetism.展开更多
The effect of martensite–austenite(M–A)constituents formed in thermo-mechanical controlled process on impact toughness of 20CrNi2MoV steel was investigated.The variation in fraction,size and morphology of M–A const...The effect of martensite–austenite(M–A)constituents formed in thermo-mechanical controlled process on impact toughness of 20CrNi2MoV steel was investigated.The variation in fraction,size and morphology of M–A constituent and its effect on toughness under different cooling rates were carried out.The result shows that there was no significant change in the fraction of M–A constituent under different cooling rates,but the distribution and size of M–A constituent were greatly influenced by cooling rate,which consequently influenced toughness.The amount of large blocky M–A constituents decreased from 4.7%to 1.7%,while that of elongated M–A constituents increased from 3.8%to 8.6%with the cooling rate increasing from 7 to 26°C/s,and the corresponding impact energy decreased from 132 to 84 J.The deterioration of impact toughness could be related to the increase in the elongated M–A constituents.The elongated M–A constituents existing along the prior austenite grain boundaries in samples of 26°C/s could easily lead to the formation of cleavage crack,which then results in the lower crack initiation energy than that of low cooling rate samples.展开更多
The effects of two alloying elements,i.e.,yttrium(Y)and zirconium(Zr),on the inclusion,microstructure,tensile property and impact toughness of reduced activation ferritic/martensitic(RAFM)steel are analyzed.The size a...The effects of two alloying elements,i.e.,yttrium(Y)and zirconium(Zr),on the inclusion,microstructure,tensile property and impact toughness of reduced activation ferritic/martensitic(RAFM)steel are analyzed.The size and number of particles were determined by optical microscopy,and the particle types were examined by scanning electron microscopy.The size of?20% and?85% of the inclusions lied in the range of 0.5-1.0μm and 0.5-3.0μm,respectively.In Y-and Y-Zr-containing specimens,the density of the fine inclusions,with a size less than 0.5μm,was found to be 1.06×10^17 and 9.82×10^16 m^-3.respectively.All specimens were normalized at 1323 K for 30 min and tempered at 923 and 1023 K for 90 min,resulting in the formation of tempered martensite with M23C6 carbides and MX precipitates.Zr-containing RAFM steel tempered at 923 K formed M23C6 carbides and nano-sized carbides with Zr,conferring superior strength balance and impact toughness.The yield strength of alloy reached 695 MPa,and a low ductile-brittle transition temperature of 238 K was maintained.展开更多
In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tr...In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tribological properties of Cu-based composites were investigated systematically. The results show that Cu matrix reacts with NbSo.2Sel.8 to produce Cu2Se and Cu0.38NbSo.2Se1.8 during sintering process, which influences the physical and tribological properties of Cu-based composites significantly. Specially, with NbS0.2Se1.8 content increasing, the density of Cu/ NbSo.2Se1.8 composites decreases, and the hardness increases firstly and then decreases, while the electric resistivity in- creases slightly. In addition, the incorporation of NbSo.2Se1.8 enhances the tribological properties of Cu greatly, which is attributed to the lubricating effect of Cuo,38NbSo.2Se1.8 and the reinforcement effect of Cu2Se. In particular, when the content of NbSo.2Sel.8 is 6 wt%, the Cu-based composite has the best tribological properties.展开更多
Microstructure and mechanical properties in core of a carburizing 20CrNi2MoV bearing steel subjected to cryogenic treatment were investigated.Conventional treatment sample was quenched and tempered at 180℃ for 2 h.Cr...Microstructure and mechanical properties in core of a carburizing 20CrNi2MoV bearing steel subjected to cryogenic treatment were investigated.Conventional treatment sample was quenched and tempered at 180℃ for 2 h.Cryogenic treatment samples were quenched,cryogenically treated at−80 and−196℃ for 4 h,slowly returned to room temperature and thereafter tempered at 180℃ for 2 h,and finally tempered at 180℃ for 2 h.The scanning electron microscope,electron backscattering diffraction,X-ray diffraction and transmission electron microscope were adopted for microstructure characterization.The results show that cryogenic treatment increases the fraction of high-angle grain boundaries and the precipitation of finely dispersed carbides in the matrix,decreases the volume fraction of inter-lath retained austenite,and hence improves the strength and hardness.Compared with the conventional treatment,the hardness,yield strength and ultimate tensile strength of the steel after cryogenic treatment are increased by 11.7%,12.6%and 18.3%,respectively,while the impact energy is decreased by 9.8%.展开更多
基金supported by the National Key Research and Development Program of China(grant number:2017YFC0806503)。
文摘With the increasing number of vehicles,manual security inspections are becoming more laborious at road checkpoints.To address it,a specialized Road Checkpoints Robot(RCRo)system is proposed,incorporated with enhanced You Only Look Once(YOLO)and a 6-degree-of-freedom(DOF)manipulator,for autonomous identity verification and vehicle inspection.The modified YOLO is characterized by large objects’sensitivity and faster detection speed,named“LF-YOLO”.The better sensitivity of large objects and the faster detection speed are achieved by means of the Dense module-based backbone network connecting two-scale detecting network,for object detection tasks,along with optimized anchor boxes and improved loss function.During the manipulator motion,Octree-aided motion control scheme is adopted for collision-free motion through Robot Operating System(ROS).The proposed LF-YOLO which utilizes continuous optimization strategy and residual technique provides a promising detector design,which has been found to be more effective during actual object detection,in terms of decreased average detection time by 68.25%and 60.60%,and increased average Intersection over Union(Io U)by 20.74%and6.79%compared to YOLOv3 and YOLOv4 through experiments.The comprehensive functional tests of RCRo system demonstrate the feasibility and competency of the multiple unmanned inspections in practice.
基金Supported by National Natural Science Foundation of China,No.81172349 and No.30872491
文摘AIM:To evaluate whether the application of sorafenib during the peri-operative period of liver transplantation improves prognosis in liver cancer patients.METHODS:We searched Pub Med,EMBASE and MEDLINE for eligible articles.A total of 4 studieswere found that fulfilled the previously agreed-upon standards.We then performed a systematic review and meta-analysis on the enrolled trials that met the inclusion criteria.RESULTS:Out of the 104 studies identified in the database,82 were not clinical experiments,and 18 did not fit the inclusion standards.Among the remaining 4 articles,only 1 was related to the preoperative use of sorafenib,whereas the other 3 were related to its postoperative use.As the heterogeneity among the 4 studies was high,with an I2 of 86%,a randomized effect model was applied to pool the data.The application of sorafenib before liver transplantation had a hazard ratio(HR) of 3.29 with a 95% confidence interval(CI) of 0.33-32.56.The use of sorafenib after liver transplantation had an HR of 1.44(95%CI:0.27-7.71).The overall pooled HR was 1.68(95%CI:0.41-6.91).CONCLUSION:The results showed that the use of sorafenib during the peri-operative period of liver transplantation did not improve patient survival significantly.In fact,sorafenib could even lead to a worse prognosis,as its use may increase the hazard of poor survival.
基金financially supported by of the National Natural Science Foundation of China(Nos.51174057 and 51274062)the National High Technology Research and Development Program of China(No.2012AA03A503)the Research Fund for the Doctoral Program of Higher Education of China(No.20130042110040)
文摘The magnetic properties of highly grain-oriented electrical steel vary along different directions. In order to investigate these properties, standard Epstein samples were cut at different angles to the rolling direction. The hard magnetization direction was found at an angle of 60° to the rolling direction. To compare the measured and fitting curves, when the magnetic field intensity is higher than 7000 A/m, it is appropriate to simulate the relation of magnetic permeability and magnetization angle using the conventional elliptical model. When the magnetic field intensity is less than 3000 A/m, parabolic fitting models should be used; but when the magnetic field intensity is between 3000 and 7000 A/m, hybrid models with high accuracy, as proposed in this paper, should be applied. Piecewise relation models of magnetic permeability and magnetization angle are significant for improving the accuracy of electromagnetic engineering calculations of electrical steel, and these new models could be applied in further industrial applications.
基金supported by the Sichuan Famous Chinese Medicine Studio Construction Project.
文摘Diabetes is a chronic disease characterized by hyperglycemia,of which type 2 diabetes mellitus(T2DM)accounts for about 95%[1].In addition,the prevalence of T2DM is still rising,seriously threatening human health.As the mechanism of T2DM is not fully understood,most of the current drugs for the treatment of T2DM focus on lowering blood glucose without solving its underlying problem.This review discusses the application of ginseng-jujube-licorice group in T2DM based on theory of traditional Chinese medicine and research of modern pharmacology,in order to provide a reference for the development of new drugs and future research.
基金Sponsored by the National Natural Science Foundation of China (Grant No. 51174057 and 51274062)National High Technology Research and Development Program (Grant No. 2012AA03A503)
文摘The effect of ball scribing on iron loss of conventional grain-oriented ( CGO) and high-permeability grain-oriented ( HGO) electrical steel was investigated. In this paper,ball scribing was achieved by self- designed ball scribing instrument and a computer-controlled system capable of providing high accuracy and automatic measurements was developed for the magnetisation and measurement at high and low flux densities. The results showed that after ball scribing,iron loss of two types of steel ( C711 and H668 ) apparently decreases ( 5. 5% and 8. 2% respectively after 16mm scribing at 1. 2T) ,and at high and low flux densities, CGO and HGO electrical steel performs differently. Through the formation and development of free magnetic poles and secondary magnetic domains due to compressive stress,primary magnetic domain spacing of grain- oriented electrical steel becomes smaller,which reflects as a reduction of iron loss in the macroscopic magnetic properties. Through iron loss formula derivation,the effect of domain refinement on grain-oriented electrical steel was also interpreted.
文摘BACKGROUND The corona virus disease 2019(COVID-19)has been a pandemic for more than one year and estimated to affect the whole world in the near future.CASE SUMMARY Here we reported that one COVID-19 patient with vesicles was treated by bullectomy.The patient’s perioperative laboratory tests were analyzed.The pathological findings of bullectomy were described and compared with those of common bulla cases.CONCLUSION This patient with vesicles underwent bullectomy and had a poor prognosis.He showed diffuse alveolar damage and extensive necrosis in bullectomy specimen.We hope our report will be of interest for clinicians who will treat COVID-19 patients in the future.
基金supported by the National Natural Science Foundation of China(Grant Nos.52293401,52205494,52293405)the State Key Laboratory of Mechanical System and Vibration in China(Grant No.MSV202103)+2 种基金the Key Research and Development Projects of Shaanxi Province in China(Grant No.2021GXLH-Z-051)the Shenzhen Key Laboratory of Cross-scale Manufacturing Mechanics Project(Grant No.ZDSYS20200810171201007)the Guangdong Specific Discipline Project(Grant No.2020ZDZX2006).
文摘Understanding the fracture behavior of fused silica in contact sliding is important to the fabrication of damage-free optics.This study develops an analytical method to characterize the stress field in fused silica under contact sliding by extending the embedded center of dilation(ECD)model and considering the depth of yield region.The effects of densification on the stress fields were considered by scratch volume analysis and finite element analysis.Key mechanisms,such as crack initiation and morphology evolution were comprehensively investigated by analyzing the predicted stress fields and principal stress trajectories.The predictions were validated by Berkovich scratching experiment.It was found that partial conical,median and lateral cracks could emerge in the loading stage of the contact sliding,but radial and lateral cracks could be initiated during unloading.It was also found that the partial conical crack had the lowest initiation load.The intersection of long lateral cracks makes the material removal greater.
基金Sponsored by National Natural Science Foundation of China(51174057,51274062)National High Technology Research and Development Program of China(2012AA03A503)
文摘The thermal scratch significantly influences the surface quality of the cold rolled stainless steel strip. In or der to establish a precise mathematical model of oil film thickness in deformation zone, the lubrication in cold rolling process of B443NT stainless steel strip was studied in the laboratory. According to the principle of statistics, a math- ematical model of critical oil film thickness in deformation zone for thermal scratch was built, with fitting and regres- sion analytical method, and then based on temperature comparison method, the criterion for deciding thermal scratch defect was put forward. Storing and calling data through SQI. Server 2005, a software on thermal scratch control was developed in the Microsoft Visual Studio 2008 environment by MFC technique for stainless steel in tandem cold roll- ing, and then it was used into the practical production. Statistical results demonstrated that the hit rate of thermal scratch arrives at 91.47%, the occurrence rate of thermal scratch is decreased by 87.81%, and rolling speed is in- creased by 7.3%. The developed software is of significance to the control of products quality of stainless steel strips, and the analysis and solution to the problem of thermal scratch defects in tandem cold rolling.
基金Sponsored by National Natural Science Foundation of China(51174057,51274062)National High-technology Researchand Development Program of China(2012AA03A503)
文摘The thermal scratch significantly influences the surface quality of the stainless steel in cold strip rolling. The thermal scratch has a close relation to the rolling parameters, the rolls surface and the emulsions used in rolling. In order to explain the thermal scratch on the strip surface, the cold roiling process of SUS430 stainless steel strip was investigated in the laboratory. The thermal scratch defect occurs frequently in the second rolling pass （maximum reduction in height is 32.3 ~）, especially on the lower surface of strips. When concentration and temperature of the emulsion are the same, the thermal scratch on the surface o{ the strip is aggravated with increasing the roll surface roughness. With the same roll surface roughness and emulsion concentration, the thermal scratch is obviously more severe at an emulsion temperature of 63 ℃ than 55 ℃. With the same roll surface roughness and emulsion tempera- ture, the thermal scratch is distinctly weaker at the emulsion concentration of 6 % than that of 3 %.
文摘Background：A single drilled tunnel from the lateral mastoid cortex to the cochlea via the facial recess is essential for minimally invasive cochlear implant surgery.This study aimed to explore the safety profile of this kind of new image-guided and bi-planar device-assisted surgery procedure in vitro.Methods：Image-guided minimally invasive cochlear implantations were performed on eight cadaveric temporal bone specimens.The main procedures were：（1） temporal bone specimens were prepared for surgery and fiducial markers were registered.（2） computed tomography （CT） scans were performed for future reference.（3） CT scan images were processed and drill path was planned to minimize cochlear damage.（4） bi-planar device-assisted drilling was performed on the specimens using the registration.（5） surgical safety was evaluated by calculating the deviation between the drill and the planned paths,and by measuring the closest distance between the drilled path and critical anatomic structures.Results：Eight cases were operated successfully to the basal turn of the cochlear with intact facial nerves （FNs）.The deviations from target points and entrance points were 0.86 mm （0.68-1.00 mm） and 0.44 mm （0.30-0.96 mm）,respectively.The angular error between the planned and the drilled trajectory was 1.74° （1.26-2.41°）.The mean distance from the edge of the drilled path to the FN and to the external canal was 0.60 mm （0.35-0.83 mm） and 1.60 mm （1.30-2.05 mm）,respectively.In five specimens,the chorda tympani nerves were well preserved.In all cases,no injury happened to auditory ossicles.Conclusions：This exploratory study demonstrated the safety of the newly developed image-guided minimally invasive cochlear implantation assisted by the bi-planar device and established the operational procedures.Further,more in vitro experiments are needed to improve the system operation and its safety.
基金Item Sponsored by National Natural Science Foundation of China(51174057,51274062)National High Technology Research and Development Program of China(2012AA03A503)
文摘Magnetic shielding of grain-oriented silicon steel was investigated. Ball scribing with spacing of 2 to 16 mm was performed at peak flux densities of 8.0 mT to 1.3 T. Magnetic shielding efficiency was calculated, including absorption, reflection and inner multi-reflection shielding efficiencies. Magnetic shielding efficiency （MSE） increase ratios after different scribing spacing were compared, and thickness requirement to achieve absorption shielding of 50 dB was also calculated. The results show that magnetic shielding efficiencies of C711 and H668 silicon steels increase by 4.79 and 3.15 dB respectively after scribing of 16 mm. Before scribing, shielding efficiency of H668 steel was higher than that of C711 steel, while after scribing, both absorption and shielding efficiency gaps were largely abridged between C711 and H668 steels. Plate thickness of C711 steel could be reduced from 3.18 mm without scribing to 2. 20 mm after scribing of 16 mm. There is no apparent thickness reduction at lower flux densities; while the peak flux density is above 0.3 T, the shielding effect becomes apparent, and the thickness could be reduced from 2.28 mm without scribing to 1.70 mm with scribing spacing of 16 ram. Magnetizing process and its effect on variation of magnetic shielding were also analyzed.
基金supported by National Natural Science Foundation of China(Nos.61871378,U2003111,62122013 and U2001211).
文摘Action recognition and localization in untrimmed videos is important for many applications and have attracted a lot of attention. Since full supervision with frame-level annotation places an overwhelming burden on manual labeling effort, learning with weak video-level supervision becomes a potential solution. In this paper, we propose a novel weakly supervised framework to recognize actions and locate the corresponding frames in untrimmed videos simultaneously. Considering that there are abundant trimmed videos publicly available and well-segmented with semantic descriptions, the instructive knowledge learned on trimmed videos can be fully leveraged to analyze untrimmed videos. We present an effective knowledge transfer strategy based on inter-class semantic relevance. We also take advantage of the self-attention mechanism to obtain a compact video representation, such that the influence of background frames can be effectively eliminated. A learning architecture is designed with twin networks for trimmed and untrimmed videos, to facilitate transferable self-attentive representation learning. Extensive experiments are conducted on three untrimmed benchmark datasets (i.e., THUMOS14, ActivityNet1.3, and MEXaction2), and the experimental results clearly corroborate the efficacy of our method. It is especially encouraging to see that the proposed weakly supervised method even achieves comparable results to some fully supervised methods.
基金Item Sponsored by Research Fund for the Central Universities of China(N130607002)National Natural Science Foundation of China(51174057,51274062)Research Fund for the Doctoral Program of Higher Education of China(20130042110040)
文摘Microstructural evolution and mechanical properties of cryogenic rolled Fe-36Ni steel were investigated. The annealed Fe-36Ni steel was rolled at cryogenic temperature（ 123-173 K） with 20%- 90% rolling reduction in thickness.The deformation process was accompanied by twinning at cryogenic temperature,and the mean thickness of deformation twins was about 200 nm with 20% rolling reduction. When the rolling reduction was above 40%,twinning was suppressed due to the stress concentration in the tested steel. Deformation microstructure of Fe-36Ni steel consisted of both twin boundaries and dislocations by cryogenic rolling（ CR）,while it only contained dislocations after rolling at room temperature（ RT）. The tensile strength of Fe-36Ni steel was improved to 930 MPa after 90% reduction at cryogenic temperature,while the tensile strength after 90% reduction at RT was only 760 MPa. More dislocations could be produced as the nucleation sites of recrystallization during CR process.
基金Item Sponsored by National Natural Science Foundation of China(51274062)
文摘Based on the rigid-plastic finite element method（FEM）, the shear stress field of deformation region for high manganese austenite steel during hot asymmetrical rolling process was analyzed. The influences of rolling parameters, such as the velocity ratio of upper to lower rolls, the initial temperature of workpiece and the reduction rate, on the shear deformation of three nodes in the upper, center and lower layers were discussed. As the rolling parameters change, distinct shear deformation appears in the upper and lower layers, but the shear deformation in the center layer appears only when the velocity ratio is more than 1.00, and the absolute value of the shear stress in this layer is changed with rolling parameters. A mathematical model which reflected the change of the maximal absolute shear stress for the center layer was established, by which the maximal absolute shear stress for the center layer can be easily calculated and the appropriate rolling technology can be designed.
基金financially supported by the National High Technology Research and Development Program of China(No.2012AA03A503)the National Natural Science Foundation of China(Nos.51174057 and 51274062)Research Fund for the Doctoral Program of Higher Education of China(No.20130042110040)
文摘Thermo-mechanical process and continuous cooling process were carried out on 20CrNi2MoV steel. Three cooling rates were implemented to optimize the mechanical properties. The microstructure evolution, precipitation behavior, and strengthening mechanisms were systematically investigated, and the fracture mechanisms were analyzed via combination of impact fracture morphologies and deflection-load curves. The experimental results indicate that the transformed microstructure of experimental steel is all complex consisting of granular bainitic ferrite and bainitic ferrite with dispersed martensite/austenite （M/A） constituents in the matrix at cooling rates of 13, 21, and 29 ℃/s. When the cooling rate increases, the grain of the steel is obviously refined. The sizes of the bainitic ferrite are 5.8, 4.7, and 3.1 μm under cooling rates of 13, 21, and 29 ℃/s, respectively. The refinement of the bainitic ferrite plays a dominant role in strength increasing and also contributes to high crack propagation energy. However, the morphologies of M/A constituents obtained under different cooling rates contribute to different crack initiation energies and then affect the impact property.
基金supported by the National Key Research Project of China(2016YFB0300402)。
文摘It is a common technical difficulty to improve the strength of low magnetic stainless steel plates on the premise of ensuring ductility,corrosion resistance,and low magnetism.In this paper,the chemical composition of low magnetic stainless steels with excellent paramagnetic stabilities and corrosion resistances was formulated through composition design and calculation.Through the alloying of Nb,V,and N and the controlled hot rolling process,large numbers of uniformly distributed high-temperature second phase particles were formed in the steel plate,and low magnetic stainless steel 35 mm plate with yield strength,ultimate tensile strength and elongation of 407 MPa,739 MPa and 54%respectively were obtained.The main strengthening strategies of the steel were solid solution strengthening and precipitation strengthening.The precipitation law and types of the high-temperature second phase in the steel were explored.The micro structure of the steel plate was characterized by scanning electron microscope,electron probe microanalysis,and transmission electron microscope.The magnetic properties of the steel plate were tested by a vibrating sample magnetometer.The relative magnetic permeability of the hot rolled plate was 1.0063 which met the requirement of low magnetism.
文摘The effect of martensite–austenite(M–A)constituents formed in thermo-mechanical controlled process on impact toughness of 20CrNi2MoV steel was investigated.The variation in fraction,size and morphology of M–A constituent and its effect on toughness under different cooling rates were carried out.The result shows that there was no significant change in the fraction of M–A constituent under different cooling rates,but the distribution and size of M–A constituent were greatly influenced by cooling rate,which consequently influenced toughness.The amount of large blocky M–A constituents decreased from 4.7%to 1.7%,while that of elongated M–A constituents increased from 3.8%to 8.6%with the cooling rate increasing from 7 to 26°C/s,and the corresponding impact energy decreased from 132 to 84 J.The deterioration of impact toughness could be related to the increase in the elongated M–A constituents.The elongated M–A constituents existing along the prior austenite grain boundaries in samples of 26°C/s could easily lead to the formation of cleavage crack,which then results in the lower crack initiation energy than that of low cooling rate samples.
基金National Natural Science Foundation of China(Nos.51874081 and 51574063)Fundamental Research Funds for the Central Universities(N150204012).
文摘The effects of two alloying elements,i.e.,yttrium(Y)and zirconium(Zr),on the inclusion,microstructure,tensile property and impact toughness of reduced activation ferritic/martensitic(RAFM)steel are analyzed.The size and number of particles were determined by optical microscopy,and the particle types were examined by scanning electron microscopy.The size of?20% and?85% of the inclusions lied in the range of 0.5-1.0μm and 0.5-3.0μm,respectively.In Y-and Y-Zr-containing specimens,the density of the fine inclusions,with a size less than 0.5μm,was found to be 1.06×10^17 and 9.82×10^16 m^-3.respectively.All specimens were normalized at 1323 K for 30 min and tempered at 923 and 1023 K for 90 min,resulting in the formation of tempered martensite with M23C6 carbides and MX precipitates.Zr-containing RAFM steel tempered at 923 K formed M23C6 carbides and nano-sized carbides with Zr,conferring superior strength balance and impact toughness.The yield strength of alloy reached 695 MPa,and a low ductile-brittle transition temperature of 238 K was maintained.
基金financially supported by the National Nature Science Foundation of China(Nos.51405199 and21301075)the Natural Science Foundation of Jiangsu Province(Nos.BK20140551 and BK20140562)+4 种基金the Postdoctoral Science Foundation of China(No.2014M561579)the Postdoctoral Science Foundation of Jiangsu Province(No.1401106C)the Opening Foundation of Jiangsu Province Material Tribology Key Laboratory(No.Kjsmcx201304)the Senior Intellectuals Fund of Jiangsu University(No.13JDG099)the Industry-Academy-Research Union Foundation of Jiangsu Province(No.BY2013065-05)
文摘In this study, S-doped NbSea （NbSo.aSel.8） powders were fabricated, and the corresponding Cu-based composites （Cu/NbSo.eSe1.8） were obtained by powder metallurgy technique. The phase compositions, physical, and tribological properties of Cu-based composites were investigated systematically. The results show that Cu matrix reacts with NbSo.2Sel.8 to produce Cu2Se and Cu0.38NbSo.2Se1.8 during sintering process, which influences the physical and tribological properties of Cu-based composites significantly. Specially, with NbS0.2Se1.8 content increasing, the density of Cu/ NbSo.2Se1.8 composites decreases, and the hardness increases firstly and then decreases, while the electric resistivity in- creases slightly. In addition, the incorporation of NbSo.2Se1.8 enhances the tribological properties of Cu greatly, which is attributed to the lubricating effect of Cuo,38NbSo.2Se1.8 and the reinforcement effect of Cu2Se. In particular, when the content of NbSo.2Sel.8 is 6 wt%, the Cu-based composite has the best tribological properties.
基金The authors are grateful to the funding by National High Technology Research and Development Program of China(863 Program,Grant No.2012AA03A503).
文摘Microstructure and mechanical properties in core of a carburizing 20CrNi2MoV bearing steel subjected to cryogenic treatment were investigated.Conventional treatment sample was quenched and tempered at 180℃ for 2 h.Cryogenic treatment samples were quenched,cryogenically treated at−80 and−196℃ for 4 h,slowly returned to room temperature and thereafter tempered at 180℃ for 2 h,and finally tempered at 180℃ for 2 h.The scanning electron microscope,electron backscattering diffraction,X-ray diffraction and transmission electron microscope were adopted for microstructure characterization.The results show that cryogenic treatment increases the fraction of high-angle grain boundaries and the precipitation of finely dispersed carbides in the matrix,decreases the volume fraction of inter-lath retained austenite,and hence improves the strength and hardness.Compared with the conventional treatment,the hardness,yield strength and ultimate tensile strength of the steel after cryogenic treatment are increased by 11.7%,12.6%and 18.3%,respectively,while the impact energy is decreased by 9.8%.
