Achieving intrinsic strengthening of boron nitride nanosheets(BNNSs)in Ti matrix composites was still an unsettled issue due to its severe and uncontrollable interface reaction.In the present study,high-performance BN...Achieving intrinsic strengthening of boron nitride nanosheets(BNNSs)in Ti matrix composites was still an unsettled issue due to its severe and uncontrollable interface reaction.In the present study,high-performance BNNSs/Ti composites were fabricated by using the warm compaction(WC)technique and rapid heat treatment(HT)strategy on the basis of interfacial nano-TiBw design.The intrinsic structure of BNNSs was well-retained and nano-TiBw on partially reacted BNNSs led to a brilliant interface bond-ing and BNNSs intrinsic strengthening.Tensile tests revealed that 0.1 wt.%BNNSs/Ti composites exhibited the tensile strength(UTS)of 876 MPa(61%higher than pure Ti)and the fracture elongation of 22.6%,demonstrating the well-balanced property.By employing the insitu TEM experiment,we solve an existing debate,uncovering the synergistic toughening effect from BNNSs and interfacial nano-TiBw which effectively inhibited the micro-cracks propagation on BNNSs and heterogeneous interface.This work paves a new way for developing high-performance BNNSs/Ti composites by reaction interface manipulation and underscores the importance of maintaining BNNSs intrinsic structure in the Ti matrix.展开更多
A three-dimensional laser absorption model based on ray tracing was established to describe the coupled interaction of a laser beam with particles in the powder layers of pure tungsten(W)material processed by selectiv...A three-dimensional laser absorption model based on ray tracing was established to describe the coupled interaction of a laser beam with particles in the powder layers of pure tungsten(W)material processed by selective laser melting(SLM).The influence of particle size on the powder-to-laser absorptivity and underlying absorption behavior was investigated.An intrinsic relationship between the absorption,distribution of absorbed irradiance within the powder layers,and surface morphology and geometric characteristics(e.g.,contact angle,width and height of tracks,and remelted depth)of the laser scanning tracks is presented here.Simulation conclusions indicate that the absorptivity of the powder layers considerably exceeds the single powder particle value or the dense solid material value.With an increase in particle size,the powder layer absorbs less laser energy.The maximum absorptivity of theWpowder layers reached 0.6030 at the particle size of 5 lm.The distribution of laser irradiance on the particle surface was sensitive to particle size,azimuthal angle,and the position of the powder particles on the substrate.The maximum irradiance in the powder layers decreased from 1.117×10^–3 to 0.85×10^–3W·μm^-2 and the contour of the irradiance distribution in the center of the irradiated area gradually contracted when the particle size increased from 5 to 45 lm.An experimental study on the surface morphologies and cross-sectional geometric characteristics of SLM-fabricated W material was performed,and the experimental results validated the mechanisms of the powder-to-laser-absorption behavior that were obtained in simulations.This work provides a scientific basis for the application of the ray-tracing model to predict the wetting and spreading ability of melted tracks during SLM additive manufacturing in order to yield a sound laser processability.展开更多
Electrochemical measurements on three planes of TiC/Inconel 718 composites fabricated by selective laser melting(SLM) were performed to study the corrosion property. The results showed that the YZplane with dense and ...Electrochemical measurements on three planes of TiC/Inconel 718 composites fabricated by selective laser melting(SLM) were performed to study the corrosion property. The results showed that the YZplane with dense and fine columnar structures possessed high microhardness and superior corrosion resistance in 3.5 wt% NaCl solution. For the XZ-plane, a decreased anti-corrosion property was observed owing to its inhomogeneous microstructures. While the XY-plane with large irregular pores and clustered ring-like structures was more susceptible to corrosion compared with the other two planes. Comparative analysis suggested that the anisotropic corrosion behaviors were significantly dependent on the surface defects, microstructure characteristics and added reinforcements.展开更多
Early childhood caries(ECC)is a significant chronic disease of childhood and a rising public health burden worldwide.ECC may cause a higher risk of new caries lesions in both primary and permanent dentition,affecting ...Early childhood caries(ECC)is a significant chronic disease of childhood and a rising public health burden worldwide.ECC may cause a higher risk of new caries lesions in both primary and permanent dentition,affecting lifelong oral health.The occurrence of ECC has been closely related to the core microbiome change in the oral cavity,which may be influenced by diet habits,oral health management,fluoride use,and dental manipulations.So,it is essential to improve parental oral health and awareness of health care,to establish a dental home at the early stage of childhood,and make an individualized caries management plan.Dental interventions according to the minimally invasive concept should be carried out to treat dental caries.This expert consensus mainly discusses the etiology of ECC,caries-risk assessment of children,prevention and treatment plan of ECC,aiming to achieve lifelong oral health.展开更多
The effects of the deformation in the non-recrystallization region of austenite and the cooling rate on the transformation behavior and microstructure of low-carbon low-alloy steel for pipeline application were studie...The effects of the deformation in the non-recrystallization region of austenite and the cooling rate on the transformation behavior and microstructure of low-carbon low-alloy steel for pipeline application were studied on the thermal-mechanical simulator Gleeble-1500. It was shown that an increase in deformation amount can greatly increase the nucleation site of ferrite when deformed in the non-recrystallization region of austenite, and an increase in nucleation ratio can greatly refine grains. When the cooling rate is accelerated, the driving force of nucleation is increased and the nucleation rate also improves. Ultra-refine grains can be obtained by controlled rolling. The high density of ferrite nucleus, which forms along the austenite grain boundary, twin interface, and deformation band are introduced in the matrix of austenite by the control of hot rolling, after which the microstructure can be refined. It was found that the acicular ferrite has a very fine sub-structure, high dislocation density, and a thin slab with ultra-fine grains. Small M/A islands and cementite are precipitated on the matrix of the slabs by the analysis technique of TEM and SEM.展开更多
Chuanxiong Rhizoma is a widely used Chinese herbal medicine in the past 2000 years.Chuanxiong Rhizoma is composed of volatile oils,phthalide lactones,phenolic acids,polysaccharides and other compounds.To date,more tha...Chuanxiong Rhizoma is a widely used Chinese herbal medicine in the past 2000 years.Chuanxiong Rhizoma is composed of volatile oils,phthalide lactones,phenolic acids,polysaccharides and other compounds.To date,more than 149 compounds in Chuanxiong Rhizoma have been isolated and identified,and some of them have been reported to possess promising biological properties on cardiovascular and central nervous system disorders besides their anti-cancer and antioxidant effects.Modulation of inflammatory mediators and apoptotic factors are believed to contribute to its bioactivities.Analytical methods,such as HPLC,GC and UPLC,are employed for qualitative evaluation of Chuanxiong Rhizoma.In this work,harvest period,growing habitat,processing method and storage,which can affect the quality of Chuanxiong Rhizoma,were also discussed.Comprehensive quality control methods should be developed to ensure the safety,quality and efficacy use of Chuanxiong Rhizoma.Herein,we collected and analyzed the literature of Chuanxiong Rhizoma published on CNKI,ScienceDirect,Springer link,Wiley and PubMed in past two decades,and up-to-date information of Chuanxiong Rhizoma was provided in this paper.We suggested ligustilide,butylidenephthalide and total senkyunolides as the chemical markers to evaluate the quality of Chuanxiong Rhizoma.Additionally,the influences of soil conditions and processing methods on Chuanxiong Rhizoma as future research perspectives should also be further assessed.展开更多
Objective:To summarize the nursing treatment of patients who underwent implantation of a blood flow diverter to treat complex intracranial aneurysms.Methods:Data from 22 patients with complex aneurysms,diagnosed at an...Objective:To summarize the nursing treatment of patients who underwent implantation of a blood flow diverter to treat complex intracranial aneurysms.Methods:Data from 22 patients with complex aneurysms,diagnosed at an interventional center for blood flow diverter implantation between February 2015 and February 2016,treated in the Henan Provincial People’s Hospital(Zhengzhou,China),were retrospectively analyzed.Nursing methods,including preoperative,intraoperative,and postoperative care,were analyzed.Results:All 22 patients underwent successful surgery,with no related complications or hospital mortality,and were cured in hospital.Conclusion:Interventional flow diverter therapy for patients with complex intracranial aneurysms is a new technology,and involves intensive care by nursing staff and appears to be a promising new treatment method.展开更多
LiNi_(0.5)Mn_(1.5)O_(4) and LiMn_(2)O_(4) with novel spinel morphology were synthesized by a hydrothermal and postcalcination process.The synthesized LiMn_(2)O_(4) particles(5–10 lm)are uniform hexahedron,while the L...LiNi_(0.5)Mn_(1.5)O_(4) and LiMn_(2)O_(4) with novel spinel morphology were synthesized by a hydrothermal and postcalcination process.The synthesized LiMn_(2)O_(4) particles(5–10 lm)are uniform hexahedron,while the LiNi_(0.5)Mn_(1.5)O_(4) has spindle-like morphology with the long axis 10–15 lm,short axis 5–8 lm.Both LiMn_(2)O_(4) and LiNi_(0.5)Mn_(1.5)O_(4) show high capacity when used as cathode materials for Li-ion batteries.In the voltage range of 2.5–5.5 V at room temperature,the LiNi_(0.5)Mn_(1.5)O_(4) has a high discharge capacity of 135.04 mA·h·g^(-1) at 20 mAg^(-1),which is close to 147 mA·h·g^(-1)(theoretical capacity of LiNi_(0.5)Mn_(1.5)O_(4)).The discharge capacity of LiMn_(2)O_(4) is 131.08 mA·h·g^(-1) at 20 mAg^(-1).Moreover,the LiNi_(0.5)Mn_(1.5)O_(4) shows a higher capacity retention(76%)compared to that of LiMn_(2)O_(4)(61%)after 50 cycles.The morphology and structure of LiMn_(2)O_(4) and LiNi_(0.5)Mn_(1.5)O_(4) are well kept even after cycling as demonstrated by SEM and XRD on cycled LiMn_(2)O_(4) and LiNi_(0.5)Mn_(1.5)O_(4) electrodes.展开更多
Metal additive manufacturing(AM)technologies have made significant progress in the basic theoretical field since their invention in the 1970s.However,performance instability during continuous processing,such as therma...Metal additive manufacturing(AM)technologies have made significant progress in the basic theoretical field since their invention in the 1970s.However,performance instability during continuous processing,such as thermal history,residual stress accumulation,and columnar grain epitaxial growth,consistently hinders their broad application in standardized industrial production.To overcome these challenges,performance-control-oriented hybrid AM(HAM)technologies have been introduced.These technologies,by leveraging external auxiliary processes,aim to regulate microstructural evolution and mechanical properties during metal AM.This paper provides a systematic and detailed review of performance-control-oriented HAM technology,which is categorized into two main groups:energy field-assisted AM(EFed AM,e.g.ultrasonic,electromagnetic,and heat)technologies and interlayer plastic deformation-assisted AM(IPDed AM,e.g.laser shock peening,rolling,ultrasonic peening,and friction stir process)technologies.This review covers the influence of external energy fields on the melting,flow,and solidification behavior of materials,and the regulatory effects of interlayer plastic deformation on grain refinement,nucleation,and recrystallization.Furthermore,the role of performance-control-oriented HAM technologies in managing residual stress conversion,metallurgical defect closure,mechanical property improvement,and anisotropy regulation is thoroughly reviewed and discussed.The review concludes with an analysis of future development trends in EFed AM and IPDed AM technologies.展开更多
Objective:To forward the magnetic resonance imaging(MRI)based distance between the deepest tumor invasion and mesorectal fascia(DMRF),and to explore its prognosis differentiation value in cT3 stage rectal cancer with ...Objective:To forward the magnetic resonance imaging(MRI)based distance between the deepest tumor invasion and mesorectal fascia(DMRF),and to explore its prognosis differentiation value in cT3 stage rectal cancer with comparison of cT3 substage.Methods:This was a retrospective,multicenter cohort study including cT3 rectal cancer patients undergoing neoadjuvant chemoradiotherapy followed by radical surgery from January 2013 to September 2014.DMRF and cT3 substage were evaluated from baseline MRI.The cutoff of DMRF was determined by disease progression.Multivariate cox regression was used to test the prognostic values of baseline variables.Results:A total of 804 patients were included,of which 226(28.1%)developed progression.A DMRF cutoff of7 mm was chosen.DMRF category,the clock position of the deepest position of tumor invasion(CDTI)and extramural venous invasion(EMVI)were independent predictors for disease progression,and hazard ratios(HRs)were 0.26[95%confidence interval(95%CI),0.13-0.56],1.88(95%CI,1.33-2.65)and 1.57(95%CI,1.13-2.18),respectively.cT3 substage was not a predictor for disease progression.Conclusions:The measurement of DMRF value on baseline MRI can better distinguish cT3 rectal cancer prognosis rather than cT3 substage,and was recommended in clinical evaluation.展开更多
Three types of scanning strategies,including the chessboard scanning strategy,the zigzag scanning strategy and the remelting scanning strategy,were conducted to study the effects of scanning strategies on surface morp...Three types of scanning strategies,including the chessboard scanning strategy,the zigzag scanning strategy and the remelting scanning strategy,were conducted to study the effects of scanning strategies on surface morphology,microstructure,mechanical properties and the grain orientation of selective laser melted pure tungsten.The results showed that the pores and cracks were main defects in SLM-processed tungsten parts.The pores could be eliminated using the remelting scanning strategy.However,the cracks seemed to be inevitable regardless of the applied scanning strategies.The microstructures of SLM-processed tungsten were columnar grains and showed strong epitaxial growth along the building direction.A compressive strength of 923 MPa with an elongation of 7.7%was obtained when the zigzag scanning strategy was applied,which was the highest among the three scanning strategies.By changing the scanning strategies,the texture of SLM-processed tungsten in the direction of processing could be changed.展开更多
MgAl-NH3 LDHs (layered double hydroxides), ZnAl-LDHs and ZnAl-NH3 LDHs with different molar ratio of Al/ammonia were synthesized by co-precipitation method. The synthetic LDHs samples were characterized by XRD, FT-IR,...MgAl-NH3 LDHs (layered double hydroxides), ZnAl-LDHs and ZnAl-NH3 LDHs with different molar ratio of Al/ammonia were synthesized by co-precipitation method. The synthetic LDHs samples were characterized by XRD, FT-IR, TGA-DTG and SEM techniques and tested by Congo red method. In addition, after PVC (Poly vinyl chloride) and DOP (Dioctylphthalate) were added to LDHs, the thermal stability for PVC was characterized by TGA-DTG. The results indicated that LDHs intercalated with ammonia improved thermal stability for PVC significantly, MgAl-NH3 LDHs (Mg2+:Al3+: NH3·H2O = 3:1:0.5) and ZnAl-NH3 LDHs (Zn2+:Al3+:NH3·H2O=2:1:1.5) showed the best thermal stability for PVC, interlayered space of LDHs became larger by intercalating ammonia.展开更多
基金the National Natural Science Foundation of China(No.52301186)the Fundamental Research Funds for the Central Universitiesthe Young Elite Scientists Sponsorship Program by CAST(Grant No.2022QNRC001).
文摘Achieving intrinsic strengthening of boron nitride nanosheets(BNNSs)in Ti matrix composites was still an unsettled issue due to its severe and uncontrollable interface reaction.In the present study,high-performance BNNSs/Ti composites were fabricated by using the warm compaction(WC)technique and rapid heat treatment(HT)strategy on the basis of interfacial nano-TiBw design.The intrinsic structure of BNNSs was well-retained and nano-TiBw on partially reacted BNNSs led to a brilliant interface bond-ing and BNNSs intrinsic strengthening.Tensile tests revealed that 0.1 wt.%BNNSs/Ti composites exhibited the tensile strength(UTS)of 876 MPa(61%higher than pure Ti)and the fracture elongation of 22.6%,demonstrating the well-balanced property.By employing the insitu TEM experiment,we solve an existing debate,uncovering the synergistic toughening effect from BNNSs and interfacial nano-TiBw which effectively inhibited the micro-cracks propagation on BNNSs and heterogeneous interface.This work paves a new way for developing high-performance BNNSs/Ti composites by reaction interface manipulation and underscores the importance of maintaining BNNSs intrinsic structure in the Ti matrix.
文摘A three-dimensional laser absorption model based on ray tracing was established to describe the coupled interaction of a laser beam with particles in the powder layers of pure tungsten(W)material processed by selective laser melting(SLM).The influence of particle size on the powder-to-laser absorptivity and underlying absorption behavior was investigated.An intrinsic relationship between the absorption,distribution of absorbed irradiance within the powder layers,and surface morphology and geometric characteristics(e.g.,contact angle,width and height of tracks,and remelted depth)of the laser scanning tracks is presented here.Simulation conclusions indicate that the absorptivity of the powder layers considerably exceeds the single powder particle value or the dense solid material value.With an increase in particle size,the powder layer absorbs less laser energy.The maximum absorptivity of theWpowder layers reached 0.6030 at the particle size of 5 lm.The distribution of laser irradiance on the particle surface was sensitive to particle size,azimuthal angle,and the position of the powder particles on the substrate.The maximum irradiance in the powder layers decreased from 1.117×10^–3 to 0.85×10^–3W·μm^-2 and the contour of the irradiance distribution in the center of the irradiated area gradually contracted when the particle size increased from 5 to 45 lm.An experimental study on the surface morphologies and cross-sectional geometric characteristics of SLM-fabricated W material was performed,and the experimental results validated the mechanisms of the powder-to-laser-absorption behavior that were obtained in simulations.This work provides a scientific basis for the application of the ray-tracing model to predict the wetting and spreading ability of melted tracks during SLM additive manufacturing in order to yield a sound laser processability.
基金financially supported by the National Natural Science Foundation of China(Nos.51735005 and 51575267)the National Key Research and Development Program “Additive Manufacturing and Laser Manufacturing”(No.2016YFB1100101)
文摘Electrochemical measurements on three planes of TiC/Inconel 718 composites fabricated by selective laser melting(SLM) were performed to study the corrosion property. The results showed that the YZplane with dense and fine columnar structures possessed high microhardness and superior corrosion resistance in 3.5 wt% NaCl solution. For the XZ-plane, a decreased anti-corrosion property was observed owing to its inhomogeneous microstructures. While the XY-plane with large irregular pores and clustered ring-like structures was more susceptible to corrosion compared with the other two planes. Comparative analysis suggested that the anisotropic corrosion behaviors were significantly dependent on the surface defects, microstructure characteristics and added reinforcements.
基金supported by the National Natural Science Foundation of China(82170947)the International Science and Technology Innovation Cooperation Projects of Science and Technology Office of Sichuan Province(2019YFH0025)。
文摘Early childhood caries(ECC)is a significant chronic disease of childhood and a rising public health burden worldwide.ECC may cause a higher risk of new caries lesions in both primary and permanent dentition,affecting lifelong oral health.The occurrence of ECC has been closely related to the core microbiome change in the oral cavity,which may be influenced by diet habits,oral health management,fluoride use,and dental manipulations.So,it is essential to improve parental oral health and awareness of health care,to establish a dental home at the early stage of childhood,and make an individualized caries management plan.Dental interventions according to the minimally invasive concept should be carried out to treat dental caries.This expert consensus mainly discusses the etiology of ECC,caries-risk assessment of children,prevention and treatment plan of ECC,aiming to achieve lifelong oral health.
文摘The effects of the deformation in the non-recrystallization region of austenite and the cooling rate on the transformation behavior and microstructure of low-carbon low-alloy steel for pipeline application were studied on the thermal-mechanical simulator Gleeble-1500. It was shown that an increase in deformation amount can greatly increase the nucleation site of ferrite when deformed in the non-recrystallization region of austenite, and an increase in nucleation ratio can greatly refine grains. When the cooling rate is accelerated, the driving force of nucleation is increased and the nucleation rate also improves. Ultra-refine grains can be obtained by controlled rolling. The high density of ferrite nucleus, which forms along the austenite grain boundary, twin interface, and deformation band are introduced in the matrix of austenite by the control of hot rolling, after which the microstructure can be refined. It was found that the acicular ferrite has a very fine sub-structure, high dislocation density, and a thin slab with ultra-fine grains. Small M/A islands and cementite are precipitated on the matrix of the slabs by the analysis technique of TEM and SEM.
基金The 12thinnovation activity plan-of undergraduates in the Shanghai University of Traditional Chinese Medicine(Grant No.2019SHUTCM060)the Natural Science Foundation of Shanghai(Grant No.19ZR1457700)+1 种基金2020 New Agricultural Science Research and Reform Practice Project of the Ministry of Education2020 Key Undergraduate Education Reform Project of Shanghai Colleges。
文摘Chuanxiong Rhizoma is a widely used Chinese herbal medicine in the past 2000 years.Chuanxiong Rhizoma is composed of volatile oils,phthalide lactones,phenolic acids,polysaccharides and other compounds.To date,more than 149 compounds in Chuanxiong Rhizoma have been isolated and identified,and some of them have been reported to possess promising biological properties on cardiovascular and central nervous system disorders besides their anti-cancer and antioxidant effects.Modulation of inflammatory mediators and apoptotic factors are believed to contribute to its bioactivities.Analytical methods,such as HPLC,GC and UPLC,are employed for qualitative evaluation of Chuanxiong Rhizoma.In this work,harvest period,growing habitat,processing method and storage,which can affect the quality of Chuanxiong Rhizoma,were also discussed.Comprehensive quality control methods should be developed to ensure the safety,quality and efficacy use of Chuanxiong Rhizoma.Herein,we collected and analyzed the literature of Chuanxiong Rhizoma published on CNKI,ScienceDirect,Springer link,Wiley and PubMed in past two decades,and up-to-date information of Chuanxiong Rhizoma was provided in this paper.We suggested ligustilide,butylidenephthalide and total senkyunolides as the chemical markers to evaluate the quality of Chuanxiong Rhizoma.Additionally,the influences of soil conditions and processing methods on Chuanxiong Rhizoma as future research perspectives should also be further assessed.
基金National Natural Science Foundation of China(81601583).
文摘Objective:To summarize the nursing treatment of patients who underwent implantation of a blood flow diverter to treat complex intracranial aneurysms.Methods:Data from 22 patients with complex aneurysms,diagnosed at an interventional center for blood flow diverter implantation between February 2015 and February 2016,treated in the Henan Provincial People’s Hospital(Zhengzhou,China),were retrospectively analyzed.Nursing methods,including preoperative,intraoperative,and postoperative care,were analyzed.Results:All 22 patients underwent successful surgery,with no related complications or hospital mortality,and were cured in hospital.Conclusion:Interventional flow diverter therapy for patients with complex intracranial aneurysms is a new technology,and involves intensive care by nursing staff and appears to be a promising new treatment method.
基金the National Natural Science Foundation of China(52022109 and 51834008)Beijing Municipal Natural Science Foundation(2202047)+1 种基金Science Foundation of China University of Petroleum,Beijing(2462018YJRC041 and 2462020YXZZ016)the Opening Project of State Key Laboratory of Advanced Chemical Power Sources(SKL-ACPS-C-20).
文摘LiNi_(0.5)Mn_(1.5)O_(4) and LiMn_(2)O_(4) with novel spinel morphology were synthesized by a hydrothermal and postcalcination process.The synthesized LiMn_(2)O_(4) particles(5–10 lm)are uniform hexahedron,while the LiNi_(0.5)Mn_(1.5)O_(4) has spindle-like morphology with the long axis 10–15 lm,short axis 5–8 lm.Both LiMn_(2)O_(4) and LiNi_(0.5)Mn_(1.5)O_(4) show high capacity when used as cathode materials for Li-ion batteries.In the voltage range of 2.5–5.5 V at room temperature,the LiNi_(0.5)Mn_(1.5)O_(4) has a high discharge capacity of 135.04 mA·h·g^(-1) at 20 mAg^(-1),which is close to 147 mA·h·g^(-1)(theoretical capacity of LiNi_(0.5)Mn_(1.5)O_(4)).The discharge capacity of LiMn_(2)O_(4) is 131.08 mA·h·g^(-1) at 20 mAg^(-1).Moreover,the LiNi_(0.5)Mn_(1.5)O_(4) shows a higher capacity retention(76%)compared to that of LiMn_(2)O_(4)(61%)after 50 cycles.The morphology and structure of LiMn_(2)O_(4) and LiNi_(0.5)Mn_(1.5)O_(4) are well kept even after cycling as demonstrated by SEM and XRD on cycled LiMn_(2)O_(4) and LiNi_(0.5)Mn_(1.5)O_(4) electrodes.
基金The financial support was provided by National Natural Science Foundation of China(Grant Numbers:52335008,52175409 and 52305469)Jiangsu Provincial Science and Technology Projects in China(Grant Numbers:BE2023026and BE2022069)+1 种基金Natural Science Foundation of Jiangsu Province(No.BK20220530)the Graduate Research Innovation Program of Jiangsu Province in China(Grant Number:KYCX23_3723)。
文摘Metal additive manufacturing(AM)technologies have made significant progress in the basic theoretical field since their invention in the 1970s.However,performance instability during continuous processing,such as thermal history,residual stress accumulation,and columnar grain epitaxial growth,consistently hinders their broad application in standardized industrial production.To overcome these challenges,performance-control-oriented hybrid AM(HAM)technologies have been introduced.These technologies,by leveraging external auxiliary processes,aim to regulate microstructural evolution and mechanical properties during metal AM.This paper provides a systematic and detailed review of performance-control-oriented HAM technology,which is categorized into two main groups:energy field-assisted AM(EFed AM,e.g.ultrasonic,electromagnetic,and heat)technologies and interlayer plastic deformation-assisted AM(IPDed AM,e.g.laser shock peening,rolling,ultrasonic peening,and friction stir process)technologies.This review covers the influence of external energy fields on the melting,flow,and solidification behavior of materials,and the regulatory effects of interlayer plastic deformation on grain refinement,nucleation,and recrystallization.Furthermore,the role of performance-control-oriented HAM technologies in managing residual stress conversion,metallurgical defect closure,mechanical property improvement,and anisotropy regulation is thoroughly reviewed and discussed.The review concludes with an analysis of future development trends in EFed AM and IPDed AM technologies.
基金supported by the National Natural Science Foundation of China(No.82071881,91959116,81971584)National Key R&D Program of China(No.2019YFC0117705)+3 种基金Beijing Municipal Administration of Hospitals Clinical Medicine Development of Special Funding Support(No.ZYLX201803)Beijing Hospitals Authority Ascent Plan(No.DFL20191103)Capital’s Funds for Health Improvement and Research(No.2020-1-2151)Beijing Natural Science Foundation(No.Z200015,Z180001)。
文摘Objective:To forward the magnetic resonance imaging(MRI)based distance between the deepest tumor invasion and mesorectal fascia(DMRF),and to explore its prognosis differentiation value in cT3 stage rectal cancer with comparison of cT3 substage.Methods:This was a retrospective,multicenter cohort study including cT3 rectal cancer patients undergoing neoadjuvant chemoradiotherapy followed by radical surgery from January 2013 to September 2014.DMRF and cT3 substage were evaluated from baseline MRI.The cutoff of DMRF was determined by disease progression.Multivariate cox regression was used to test the prognostic values of baseline variables.Results:A total of 804 patients were included,of which 226(28.1%)developed progression.A DMRF cutoff of7 mm was chosen.DMRF category,the clock position of the deepest position of tumor invasion(CDTI)and extramural venous invasion(EMVI)were independent predictors for disease progression,and hazard ratios(HRs)were 0.26[95%confidence interval(95%CI),0.13-0.56],1.88(95%CI,1.33-2.65)and 1.57(95%CI,1.13-2.18),respectively.cT3 substage was not a predictor for disease progression.Conclusions:The measurement of DMRF value on baseline MRI can better distinguish cT3 rectal cancer prognosis rather than cT3 substage,and was recommended in clinical evaluation.
基金the financial support by Science Challenge Project(Nos.TZ2018006-0301-02 and TZ2018006-0303-03)National Natural Science Foundation of China(No.51735005)National Natural Science Foundation of China for Creative Research Groups(Grant No.51921003)。
文摘Three types of scanning strategies,including the chessboard scanning strategy,the zigzag scanning strategy and the remelting scanning strategy,were conducted to study the effects of scanning strategies on surface morphology,microstructure,mechanical properties and the grain orientation of selective laser melted pure tungsten.The results showed that the pores and cracks were main defects in SLM-processed tungsten parts.The pores could be eliminated using the remelting scanning strategy.However,the cracks seemed to be inevitable regardless of the applied scanning strategies.The microstructures of SLM-processed tungsten were columnar grains and showed strong epitaxial growth along the building direction.A compressive strength of 923 MPa with an elongation of 7.7%was obtained when the zigzag scanning strategy was applied,which was the highest among the three scanning strategies.By changing the scanning strategies,the texture of SLM-processed tungsten in the direction of processing could be changed.
文摘MgAl-NH3 LDHs (layered double hydroxides), ZnAl-LDHs and ZnAl-NH3 LDHs with different molar ratio of Al/ammonia were synthesized by co-precipitation method. The synthetic LDHs samples were characterized by XRD, FT-IR, TGA-DTG and SEM techniques and tested by Congo red method. In addition, after PVC (Poly vinyl chloride) and DOP (Dioctylphthalate) were added to LDHs, the thermal stability for PVC was characterized by TGA-DTG. The results indicated that LDHs intercalated with ammonia improved thermal stability for PVC significantly, MgAl-NH3 LDHs (Mg2+:Al3+: NH3·H2O = 3:1:0.5) and ZnAl-NH3 LDHs (Zn2+:Al3+:NH3·H2O=2:1:1.5) showed the best thermal stability for PVC, interlayered space of LDHs became larger by intercalating ammonia.
