Fracture propagation mechanisms in coalbed methane(CBM) reservoirs are very complex due to the development of the internal cleat system. In this paper, the characteristics of initiation and propagation of hydraulic fr...Fracture propagation mechanisms in coalbed methane(CBM) reservoirs are very complex due to the development of the internal cleat system. In this paper, the characteristics of initiation and propagation of hydraulic fractures in coal specimens at different angles between the face cleat and the maximum horizontal principal stress were investigated with hydraulic fracturing tests. The results indicate that the interactions between the hydraulic fractures and the cleat system have a major effect on fracture networks. "Step-like’’ fractures were formed in most experiments due to the existence of discontinuous butt cleats. The hydraulic fractures were more likely to divert or propagate along the butt cleat with an increase in the angles and a decrease in the horizontal principal stress difference. An increase in the injection rate and a decrease in the fracturing fluid viscosity were more conducive to fracture networks. In addition, the influence on fracture propagation of the residual coal fines in the wellbore was also studied. The existence of coal fines was an obstacle in fracturing, and no effective connection can be formed between fractures. The experimental investigation revealed the fracture propagation mechanisms and can provide guidance for hydraulic fracturing design of CBM reservoirs.展开更多
For the public having a better understanding of solar activities,the Educational Adaptive-optics Solar Telescope(EAST)was built in July 2021 and is located at the Shanghai Astronomy Museum.The EAST consists of a 65 cm...For the public having a better understanding of solar activities,the Educational Adaptive-optics Solar Telescope(EAST)was built in July 2021 and is located at the Shanghai Astronomy Museum.The EAST consists of a 65 cm aperture solar telescope with a 177-element adaptive optics system and two-channel high resolution imaging system at the Hαand TiO bands,in addition to three full disk solar telescopes at CaK,Hαand TiO bands equipped on the tube of the main telescope.In this paper,the configuration of the EAST is described.Its performance and on-sky observational results are presented.The EAST,to our knowledge,is the most advanced solar telescope for the popularization of science in the world.Due to its excellent performance,the data acquired by the EAST can also be used for research on solar physics and space weather prediction.展开更多
Traditionally,fi sh carcass is headed and gutted to prepare a skin-on fi llet in surimi production.In this study,tail and/or belly of grass carp carcass were further cut off in the fi lleting step.Yield,composition,ge...Traditionally,fi sh carcass is headed and gutted to prepare a skin-on fi llet in surimi production.In this study,tail and/or belly of grass carp carcass were further cut off in the fi lleting step.Yield,composition,gelling properties and aroma profile of surimi as affected by filleting methods were investigated by SDS-PAGE,ELISA,SEM,magnetic resonance imaging(MRI)and electron nose.Cutting tail off increased surimi yield by 14.0%,whereas cutting belly off decreased it by 11.2%.Cutting tail or belly off signifi cantly decreased fat content,but did not change protein content,ash content,cathepsin(B,H and L)contents,nor protein patterns.Both breaking force and whiteness of surimi gel signifi cantly increased after cutting tail off.Cutting belly off slightly increased whiteness of surimi gel.The microstructure of all the surimi gels was compact and uniform,with fractal dimensions(Df)ranging from 2.81 to 2.85.As for the macrostructure,cutting tail off apparently improved the integrity of surimi gel while cutting belly off did not.Aroma profi les of the surimi prepared under different fi lleting methods could be clearly distinguished by linear discriminant analysis(LDA).Our results indicate that cutting tail off contribute positively to surimi production.展开更多
3β-Hydroxysteroid-△24 reductase （DHCR24） is a multifunctional enzyme that localizes to the endoplasmic reticulum and has neuroprotective and cholesterol-synthesizing activities. DHCR24 overexpression confers neuro...3β-Hydroxysteroid-△24 reductase （DHCR24） is a multifunctional enzyme that localizes to the endoplasmic reticulum and has neuroprotective and cholesterol-synthesizing activities. DHCR24 overexpression confers neuroprotection against apoptosis caused by amyloid β deposition. The present study aimed to construct two recombinant adenoviruses driving DHCR24 expression specifically in neurons. Two SYN1 promoter DNA fragments were obtained from human （h） and rat （r）. Recombinant Ad-r（h）SYN1-DHCR24 was transfected into AD-293, N2A （mouse neuroblastoma）, and MIN6 （mouse pancreatic carcinoma） cells. Western blot analysis showed DHCR24 was specially expressed in 293 and N2A cells, but no specific band was found in MIN6 cells. This demonstrates that the recombinant adenoviruses successfully express DHCR24, and no expression is observed in non-neuronal cells. TUNEL assay results showed apoptosis was inhibited in adenovirus-transfected neurons. Detecting reactive oxygen species by immunoflu- orescence, we found that adenovirus transfection inhibits apoptosis through scavenging excess reactive oxygen species. Our findings show that the recombinant DHCR24 adenoviruses induce neuron-specific DHCR24 expression, and thereby lay the foundation for further studies on DHCR24 gene therapy for Alzheimer＇s disease.展开更多
[Objective] The aim was to study the heat stress mechanism of differentially expressed genes in rat jejunal mucosal. [Method] Variable cluster analysis and cluster analysis of samples on the differentially expressed h...[Objective] The aim was to study the heat stress mechanism of differentially expressed genes in rat jejunal mucosal. [Method] Variable cluster analysis and cluster analysis of samples on the differentially expressed heat stress genes in rat jejunal mucosal were carried out with SAS software, and statistics of distribution of the differentially expressed genes on chromosomes were conducted. [Result] The differentially expressed genes were divided into seven categories, of which, the upregulated genes included three categories(i.e.: Category A: Hspa1 a, Hspa1 b,Hspb1, Hsph1, Dnaja4, Ahsa2 and P4ha1; Category B: Cyp1a2, Zbtb16, Gucy2 g,Fgb, Cyp4a3 and Etv2; and Category C: Cyp1a2, Chac1 and Cyp4b1) and the down-regulated genes included four categories(i.e.: Category D: Tlr2, Noxo1,LOC286989 and Aspg; Category E: RGD1560395, Alb and BQ194726; Category F:Ccl4, Gzmk, AI228153, Anxa10, S100a9 and Ascl5; and Category G: Reg1 a and Slc13a1). The classification, function and reasons of differential expression for each gene category were analyzed. [Conclusion] Most of the three categories of up-regulated genes were related to the heat shock proteins; and most of the four categories of down-regulated genes were related to the immunity, providing reference for discussion of the heat stress mechanism.展开更多
目的:监测溶瘤病毒M1在组织中的传播情况,以更好地控制给药剂量,确保安全性。方法:建立一种基于TaqMan的实时定量PCR检测法,用于对组织中溶瘤病毒M1的检测和定量,并检测静脉注射病毒后多种实验动物体内的病毒载量和分布。结果:我们以一...目的:监测溶瘤病毒M1在组织中的传播情况,以更好地控制给药剂量,确保安全性。方法:建立一种基于TaqMan的实时定量PCR检测法,用于对组织中溶瘤病毒M1的检测和定量,并检测静脉注射病毒后多种实验动物体内的病毒载量和分布。结果:我们以一对特异的引物(Q3)和标准RNA开始SYBR Green RT-qPCR研究。通过优化实验方法发现当退火温度高于62℃时可降低基质效应,但却影响了扩增效率。因此我们建立了一步法TaqMan RT-qPCR实验,重新设计了一对Q3短引物(Q3S)。运用一步TaqMan RT-qPCR检测法和Q3S引物,在混有SD大鼠或食蟹猴基质RNA的背景下,均能特异性检测到低拷贝数的标准RNA。经验证,该方法适用于检测M1病毒在小鼠、SD大鼠和食蟹猴体内的组织分布。结论:利用Q3S引物构建的TaqMan一步法RT-qPCR能够定量检测不同动物不同组织样品中的M1病毒,具有特异性和敏感性,可进一步应用于临床样品的检测。展开更多
Objective:To explore the therapeutic effect of Bufei Huaxian Decoction plus prednisone on patients with idiopathic pulmonary fibrosis. Methods:80 patients with idiopathic pulmonary fibrosis treated in our hospital fro...Objective:To explore the therapeutic effect of Bufei Huaxian Decoction plus prednisone on patients with idiopathic pulmonary fibrosis. Methods:80 patients with idiopathic pulmonary fibrosis treated in our hospital from January 2018 to January 2019 were randomly divided into prednisone group and combination group, 40 cases in each group. Prenisone group was treated with prednisone, while Bufei Huaxian Decoction plus prednisone was used in combination group. Maximum expiratory flow (PEF), forced expiratory volume (FEV1) and forced vital capacity (FVC) were measured. Hyaluronidase (HA), laminin (LN), procollagen type Ⅲ (PCIII), transforming growth factor-β1 (TGF-β1) and hypersensitive C-reactive eggs were detected by enzyme-linked immunosorbent assay (ELISA). The levels of hs-CRP, TNF-α and glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), malondialdehyde (MDA) were measured by immunoturbidimetry. The levels of T lymphocyte subsets and therapeutic effects were compared between the two groups. Results:After treatment, the levels of PEF, FEV1 and FVC in the combined group were higher than those in the prednisone group (P<0.05). After treatment, the levels of HA, LN and PC-Ⅲ in the combined group were lower than those in the prednisone group (P<0.05). After treatment, the serum levels of TGF-β1, hs-CRP and TNF-α in the combined group were lower than those in the prednisone group (P<0.05). After treatment, the serum GSH-Px and SOD levels in the combined group were higher than those in the prednisone group, and MDA levels were lower than those in the prednisone group (P<0.05). After treatment, the levels of CD8 + in the combined group were lower than those in the prednisone group, and the levels of CD4 + and CD3 + were higher than those in the prednisone group (P<0.05). The total effective rate of combined group 95.00% was higher than that of prednisone group 80.00% (P<0.05). Conclusions:Bufei Huaxian Decoction plus prednisone can improve the pulmonary function of patients with idiopathic pulmonary fibrosis, reduce the severity of pulmonary fibrosis, and enhance the antioxidant capacity and immune function of patients. The therapeutic effect is remarkable.展开更多
The microstructure and stress rupture properties of Inconel 706 alloy microalloyed with phosphorus are examined under stabilizing and unstabilizing heat treatment conditions.It was found that applying the stabilizing ...The microstructure and stress rupture properties of Inconel 706 alloy microalloyed with phosphorus are examined under stabilizing and unstabilizing heat treatment conditions.It was found that applying the stabilizing treatment resulted in a 98% increment in the stress rupture life and a 215% increment in the elongation tested at 650℃/690 MPa for the alloy compared to that under the unstabilizing heat treatment condition.The stabilizing treatment led to the precipitation of rod-shaped and needle-shaped n phases at the grain boundaries.Morphologies of γ'-γ" co-precipitates in the grain interior were noncompact form and compact form for the alloy under unstabilizing and stabilizing heat treatment conditions,respectively.Based on the microstructure characterizations,the improvement of stress rupture properties by the stabilizing treatment was attributed to the precipitation of n phases at the grain boundaries,which can hinder cracks initiation and propagation and relieve the stress concentration.展开更多
The microstructure evolutions and nucleation mechanisms of GH4169G alloy were studied by optical microscope, electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The hot compression test...The microstructure evolutions and nucleation mechanisms of GH4169G alloy were studied by optical microscope, electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The hot compression tests were performed different imposed reductions in the range of true strain from 0.12 to 1.2 at the temperatures of 930 °-1050 ° with strain rates of 0.01 s^-1-l s^-1. It is found that cumulative and local misorientation increase firstly and then decrease when the strain is increased due to the progress of dynamic recrystallization (DRX). The low angle boundaries (LAGBs) rapidly develop to high angle boundaries (HAGBs) at relatively high deformation temperature or the low strain rate. There are three DRX mechanisms observed for GH4169 G alloy during hot deformation. Discontinuous dynamic recrystallization (DDRX) as the dominant mechanism for GH4169 G alloy is characterized by typical necklace structures and bulged-original boundaries. Besides, different deformation bands with dislocation cells formed in deformed matrix at low temperature and large strain, which indicates that continuous dynamic recrystallization (CDRX) contributed to the DRX process. The twin boundaries lost their coherent characteristics and provide sites for nucleation, which also accelerates the nucleation of DRX.展开更多
The uniform corrosion behavior of model FeCrAl alloys as well as commercial Zircaloy-4 as reference material were investigated in 360℃borated and lithiated water.The results reveal that FeCrAl alloys exhibited better...The uniform corrosion behavior of model FeCrAl alloys as well as commercial Zircaloy-4 as reference material were investigated in 360℃borated and lithiated water.The results reveal that FeCrAl alloys exhibited better corrosion resistance than Zircaloy-4.It is found that the oxide films formed on the FeCrAl alloys are composed of outer Fe_(3)O_(4)layer,inner layer consisting of compact spinel layer and porous spinel layer,and transition layer containing Al-Cr-rich oxides and matrix enriched with Fe°.The spinel oxides in the inner layer are FeFe_(2-x-y-z)Cr_(x)Al_(y)MozO_(4).The corrosion mechanism of FeCrAl alloys in high temperature water is discussed.展开更多
The condition of the motor oil in civilian cars is difficult to monitor;hence,we propose a method to evaluate the degree of degradation of motor oil using an on‐board diagnostic(OBD)system.Three civilian cars and fou...The condition of the motor oil in civilian cars is difficult to monitor;hence,we propose a method to evaluate the degree of degradation of motor oil using an on‐board diagnostic(OBD)system.Three civilian cars and four motor oils(containing mineral oils and synthetic oils)were subjected to five groups of road tests under urban traffic and high‐way conditions.The operation information,oil service time,mileage,engine operation time,idle time of the engine,and number of start‐ups of the engine were obtained using the proposed OBD system.Physiochemical properties and changes in the components of motor oils during road tests were analyzed in laboratory.The theoretical model of the comprehensive indicators of driving parameters and oil properties were established.The proposed method was successfully applied to different cars,motor oils,and operating conditions in road tests.All the theoretical models had high accuracy and precision.Herein,we provide a method to monitor the oil condition with real‐time driving parameters and provide a reference for end users to change their motor oil reasonably.展开更多
Effect of segregation behaviors of P at different cooling rates on the precipitation of γ" and γ' phases and the corresponding strength are investigated. The precipitation of γ" and γ' phases dur...Effect of segregation behaviors of P at different cooling rates on the precipitation of γ" and γ' phases and the corresponding strength are investigated. The precipitation of γ" and γ' phases during cooling is sensi-tive to P concentration. With increasing the concentration of Pf the amount of γ" and γ' particles increases after air cooling. With decreasing the cooling rate, the accelerating effect of P on the precipitation of γ" and γ' phases decreased first and then increased, which demonstrates the concentration of P dissolved in the grain interior decreases first and then increases. The different effects of P on γ"and γ' phases with different cooling rates were analyzed by the kinetic characteristic of nonequilibrium grain-boundary seg-regation. The characteristic of nonequilibrium grain-boundary segregation of P in superalloy is further confirmed, and the phenomenon caused by critical cooling rate is captured.展开更多
基金funded by the National Science and Technology Major Project of China (2016ZX05046004-003)Northeast Petroleum University Innovation Foundation for Postgraduate (YJSCX2017-010NEPU and YJSCX2017-009NEPU)
文摘Fracture propagation mechanisms in coalbed methane(CBM) reservoirs are very complex due to the development of the internal cleat system. In this paper, the characteristics of initiation and propagation of hydraulic fractures in coal specimens at different angles between the face cleat and the maximum horizontal principal stress were investigated with hydraulic fracturing tests. The results indicate that the interactions between the hydraulic fractures and the cleat system have a major effect on fracture networks. "Step-like’’ fractures were formed in most experiments due to the existence of discontinuous butt cleats. The hydraulic fractures were more likely to divert or propagate along the butt cleat with an increase in the angles and a decrease in the horizontal principal stress difference. An increase in the injection rate and a decrease in the fracturing fluid viscosity were more conducive to fracture networks. In addition, the influence on fracture propagation of the residual coal fines in the wellbore was also studied. The existence of coal fines was an obstacle in fracturing, and no effective connection can be formed between fractures. The experimental investigation revealed the fracture propagation mechanisms and can provide guidance for hydraulic fracturing design of CBM reservoirs.
基金supported by the National Natural Science Foundation of China(NSFC,Grant Nos.11727805,11703029,11733005 and 12103057)。
文摘For the public having a better understanding of solar activities,the Educational Adaptive-optics Solar Telescope(EAST)was built in July 2021 and is located at the Shanghai Astronomy Museum.The EAST consists of a 65 cm aperture solar telescope with a 177-element adaptive optics system and two-channel high resolution imaging system at the Hαand TiO bands,in addition to three full disk solar telescopes at CaK,Hαand TiO bands equipped on the tube of the main telescope.In this paper,the configuration of the EAST is described.Its performance and on-sky observational results are presented.The EAST,to our knowledge,is the most advanced solar telescope for the popularization of science in the world.Due to its excellent performance,the data acquired by the EAST can also be used for research on solar physics and space weather prediction.
基金Authors gratefully acknowledge financial support from the National Key R&D Program of China(2018YFD0901003)China Agricultural Research System(CARS-45-28).
文摘Traditionally,fi sh carcass is headed and gutted to prepare a skin-on fi llet in surimi production.In this study,tail and/or belly of grass carp carcass were further cut off in the fi lleting step.Yield,composition,gelling properties and aroma profile of surimi as affected by filleting methods were investigated by SDS-PAGE,ELISA,SEM,magnetic resonance imaging(MRI)and electron nose.Cutting tail off increased surimi yield by 14.0%,whereas cutting belly off decreased it by 11.2%.Cutting tail or belly off signifi cantly decreased fat content,but did not change protein content,ash content,cathepsin(B,H and L)contents,nor protein patterns.Both breaking force and whiteness of surimi gel signifi cantly increased after cutting tail off.Cutting belly off slightly increased whiteness of surimi gel.The microstructure of all the surimi gels was compact and uniform,with fractal dimensions(Df)ranging from 2.81 to 2.85.As for the macrostructure,cutting tail off apparently improved the integrity of surimi gel while cutting belly off did not.Aroma profi les of the surimi prepared under different fi lleting methods could be clearly distinguished by linear discriminant analysis(LDA).Our results indicate that cutting tail off contribute positively to surimi production.
基金financially supported by the National Natural Science Foundation of China(General Program),No.31271494Excellent Talent Support Program of Liaoning Province,No.LJQ2011004
文摘3β-Hydroxysteroid-△24 reductase （DHCR24） is a multifunctional enzyme that localizes to the endoplasmic reticulum and has neuroprotective and cholesterol-synthesizing activities. DHCR24 overexpression confers neuroprotection against apoptosis caused by amyloid β deposition. The present study aimed to construct two recombinant adenoviruses driving DHCR24 expression specifically in neurons. Two SYN1 promoter DNA fragments were obtained from human （h） and rat （r）. Recombinant Ad-r（h）SYN1-DHCR24 was transfected into AD-293, N2A （mouse neuroblastoma）, and MIN6 （mouse pancreatic carcinoma） cells. Western blot analysis showed DHCR24 was specially expressed in 293 and N2A cells, but no specific band was found in MIN6 cells. This demonstrates that the recombinant adenoviruses successfully express DHCR24, and no expression is observed in non-neuronal cells. TUNEL assay results showed apoptosis was inhibited in adenovirus-transfected neurons. Detecting reactive oxygen species by immunoflu- orescence, we found that adenovirus transfection inhibits apoptosis through scavenging excess reactive oxygen species. Our findings show that the recombinant DHCR24 adenoviruses induce neuron-specific DHCR24 expression, and thereby lay the foundation for further studies on DHCR24 gene therapy for Alzheimer＇s disease.
基金Supported by General Program of Science and Technology Development Project of Beijing Municipal Education(KM201110020010)Non-profit Industry Technology Projectof the Ministry of Agriculture funded by Funding Program for Academic Human Resources Development in Institutions of Higher Learning Under the Jurisdiction of Beijing Municipality of China[201003060-(9-10)]
文摘[Objective] The aim was to study the heat stress mechanism of differentially expressed genes in rat jejunal mucosal. [Method] Variable cluster analysis and cluster analysis of samples on the differentially expressed heat stress genes in rat jejunal mucosal were carried out with SAS software, and statistics of distribution of the differentially expressed genes on chromosomes were conducted. [Result] The differentially expressed genes were divided into seven categories, of which, the upregulated genes included three categories(i.e.: Category A: Hspa1 a, Hspa1 b,Hspb1, Hsph1, Dnaja4, Ahsa2 and P4ha1; Category B: Cyp1a2, Zbtb16, Gucy2 g,Fgb, Cyp4a3 and Etv2; and Category C: Cyp1a2, Chac1 and Cyp4b1) and the down-regulated genes included four categories(i.e.: Category D: Tlr2, Noxo1,LOC286989 and Aspg; Category E: RGD1560395, Alb and BQ194726; Category F:Ccl4, Gzmk, AI228153, Anxa10, S100a9 and Ascl5; and Category G: Reg1 a and Slc13a1). The classification, function and reasons of differential expression for each gene category were analyzed. [Conclusion] Most of the three categories of up-regulated genes were related to the heat shock proteins; and most of the four categories of down-regulated genes were related to the immunity, providing reference for discussion of the heat stress mechanism.
基金the China Postdoctoral Science Foundation Project(No.2018M640875)National Major Scientific and Technological Special Project for Significant New Drugs Development(No.2018ZX09733002)。
文摘目的:监测溶瘤病毒M1在组织中的传播情况,以更好地控制给药剂量,确保安全性。方法:建立一种基于TaqMan的实时定量PCR检测法,用于对组织中溶瘤病毒M1的检测和定量,并检测静脉注射病毒后多种实验动物体内的病毒载量和分布。结果:我们以一对特异的引物(Q3)和标准RNA开始SYBR Green RT-qPCR研究。通过优化实验方法发现当退火温度高于62℃时可降低基质效应,但却影响了扩增效率。因此我们建立了一步法TaqMan RT-qPCR实验,重新设计了一对Q3短引物(Q3S)。运用一步TaqMan RT-qPCR检测法和Q3S引物,在混有SD大鼠或食蟹猴基质RNA的背景下,均能特异性检测到低拷贝数的标准RNA。经验证,该方法适用于检测M1病毒在小鼠、SD大鼠和食蟹猴体内的组织分布。结论:利用Q3S引物构建的TaqMan一步法RT-qPCR能够定量检测不同动物不同组织样品中的M1病毒,具有特异性和敏感性,可进一步应用于临床样品的检测。
基金Scientific research project of Guangdong traditional Chinese Medicine Bureau(No.20171246)“Three famous medical and health projects”in Shenzhen(No.SZSM201812063).
文摘Objective:To explore the therapeutic effect of Bufei Huaxian Decoction plus prednisone on patients with idiopathic pulmonary fibrosis. Methods:80 patients with idiopathic pulmonary fibrosis treated in our hospital from January 2018 to January 2019 were randomly divided into prednisone group and combination group, 40 cases in each group. Prenisone group was treated with prednisone, while Bufei Huaxian Decoction plus prednisone was used in combination group. Maximum expiratory flow (PEF), forced expiratory volume (FEV1) and forced vital capacity (FVC) were measured. Hyaluronidase (HA), laminin (LN), procollagen type Ⅲ (PCIII), transforming growth factor-β1 (TGF-β1) and hypersensitive C-reactive eggs were detected by enzyme-linked immunosorbent assay (ELISA). The levels of hs-CRP, TNF-α and glutathione peroxidase (GSH-Px), superoxide dismutase (SOD), malondialdehyde (MDA) were measured by immunoturbidimetry. The levels of T lymphocyte subsets and therapeutic effects were compared between the two groups. Results:After treatment, the levels of PEF, FEV1 and FVC in the combined group were higher than those in the prednisone group (P<0.05). After treatment, the levels of HA, LN and PC-Ⅲ in the combined group were lower than those in the prednisone group (P<0.05). After treatment, the serum levels of TGF-β1, hs-CRP and TNF-α in the combined group were lower than those in the prednisone group (P<0.05). After treatment, the serum GSH-Px and SOD levels in the combined group were higher than those in the prednisone group, and MDA levels were lower than those in the prednisone group (P<0.05). After treatment, the levels of CD8 + in the combined group were lower than those in the prednisone group, and the levels of CD4 + and CD3 + were higher than those in the prednisone group (P<0.05). The total effective rate of combined group 95.00% was higher than that of prednisone group 80.00% (P<0.05). Conclusions:Bufei Huaxian Decoction plus prednisone can improve the pulmonary function of patients with idiopathic pulmonary fibrosis, reduce the severity of pulmonary fibrosis, and enhance the antioxidant capacity and immune function of patients. The therapeutic effect is remarkable.
基金supported by the National Natural Science Foundation of China(No.52173034)the Science and Technology Innovation Program of Hunan Province of China(Nos.2023JJ30081,2022JJ40523 and 2021JJ50009)+1 种基金the Science Research Foundation of Hunan Provincial Education Department of China(No.21A0546)the Changsha Municipal Science and Technology Project(No.kq2203005).
文摘The microstructure and stress rupture properties of Inconel 706 alloy microalloyed with phosphorus are examined under stabilizing and unstabilizing heat treatment conditions.It was found that applying the stabilizing treatment resulted in a 98% increment in the stress rupture life and a 215% increment in the elongation tested at 650℃/690 MPa for the alloy compared to that under the unstabilizing heat treatment condition.The stabilizing treatment led to the precipitation of rod-shaped and needle-shaped n phases at the grain boundaries.Morphologies of γ'-γ" co-precipitates in the grain interior were noncompact form and compact form for the alloy under unstabilizing and stabilizing heat treatment conditions,respectively.Based on the microstructure characterizations,the improvement of stress rupture properties by the stabilizing treatment was attributed to the precipitation of n phases at the grain boundaries,which can hinder cracks initiation and propagation and relieve the stress concentration.
文摘The microstructure evolutions and nucleation mechanisms of GH4169G alloy were studied by optical microscope, electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). The hot compression tests were performed different imposed reductions in the range of true strain from 0.12 to 1.2 at the temperatures of 930 °-1050 ° with strain rates of 0.01 s^-1-l s^-1. It is found that cumulative and local misorientation increase firstly and then decrease when the strain is increased due to the progress of dynamic recrystallization (DRX). The low angle boundaries (LAGBs) rapidly develop to high angle boundaries (HAGBs) at relatively high deformation temperature or the low strain rate. There are three DRX mechanisms observed for GH4169 G alloy during hot deformation. Discontinuous dynamic recrystallization (DDRX) as the dominant mechanism for GH4169 G alloy is characterized by typical necklace structures and bulged-original boundaries. Besides, different deformation bands with dislocation cells formed in deformed matrix at low temperature and large strain, which indicates that continuous dynamic recrystallization (CDRX) contributed to the DRX process. The twin boundaries lost their coherent characteristics and provide sites for nucleation, which also accelerates the nucleation of DRX.
基金jointly supported by the National Natural Science Foundation of China[51671201,51971230]the National Science and Technology Major Project[2017ZX06002003-004-002]the Key Programs of the Chinese Academy of Sciences[Research on the Development of Nuclear Power Materials and Service Security Technology,ZDRW-CN-2017-1]。
文摘The uniform corrosion behavior of model FeCrAl alloys as well as commercial Zircaloy-4 as reference material were investigated in 360℃borated and lithiated water.The results reveal that FeCrAl alloys exhibited better corrosion resistance than Zircaloy-4.It is found that the oxide films formed on the FeCrAl alloys are composed of outer Fe_(3)O_(4)layer,inner layer consisting of compact spinel layer and porous spinel layer,and transition layer containing Al-Cr-rich oxides and matrix enriched with Fe°.The spinel oxides in the inner layer are FeFe_(2-x-y-z)Cr_(x)Al_(y)MozO_(4).The corrosion mechanism of FeCrAl alloys in high temperature water is discussed.
基金financial support from the National Natural Science Foundation of China(No.51575402)
文摘The condition of the motor oil in civilian cars is difficult to monitor;hence,we propose a method to evaluate the degree of degradation of motor oil using an on‐board diagnostic(OBD)system.Three civilian cars and four motor oils(containing mineral oils and synthetic oils)were subjected to five groups of road tests under urban traffic and high‐way conditions.The operation information,oil service time,mileage,engine operation time,idle time of the engine,and number of start‐ups of the engine were obtained using the proposed OBD system.Physiochemical properties and changes in the components of motor oils during road tests were analyzed in laboratory.The theoretical model of the comprehensive indicators of driving parameters and oil properties were established.The proposed method was successfully applied to different cars,motor oils,and operating conditions in road tests.All the theoretical models had high accuracy and precision.Herein,we provide a method to monitor the oil condition with real‐time driving parameters and provide a reference for end users to change their motor oil reasonably.
文摘Effect of segregation behaviors of P at different cooling rates on the precipitation of γ" and γ' phases and the corresponding strength are investigated. The precipitation of γ" and γ' phases during cooling is sensi-tive to P concentration. With increasing the concentration of Pf the amount of γ" and γ' particles increases after air cooling. With decreasing the cooling rate, the accelerating effect of P on the precipitation of γ" and γ' phases decreased first and then increased, which demonstrates the concentration of P dissolved in the grain interior decreases first and then increases. The different effects of P on γ"and γ' phases with different cooling rates were analyzed by the kinetic characteristic of nonequilibrium grain-boundary seg-regation. The characteristic of nonequilibrium grain-boundary segregation of P in superalloy is further confirmed, and the phenomenon caused by critical cooling rate is captured.
