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Construction of a Constitutively Activated Gα Mutant in the Maize Pathogen <i>Cochliobolus heterostrophus</i>
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作者 Ofir Degani 《American Journal of Plant Sciences》 2013年第12期2394-2399,共6页
Conserved eukaryotic signaling proteins participate in development and disease in plant pathogenic fungi. Mutants in CGA1, a heterotrimeric G protein Ga subunit gene of the maize pathogen Cochliobolus heterostrophus, ... Conserved eukaryotic signaling proteins participate in development and disease in plant pathogenic fungi. Mutants in CGA1, a heterotrimeric G protein Ga subunit gene of the maize pathogen Cochliobolus heterostrophus, are defective in several developmental pathways. Conidia from CGA1 mutants germinate as abnormal, straight-growing germ tubes that form few appressoria, and the mutants are female-sterile. The CGA1, Gα subunit, is also thought to act as a down regulator of hydrophobin expression and secretion in this fungus and in related Ascomycete species. Although cga1 mutants can cause normal lesions on plants there are host physiology conditions under which full virulence requires signal transduction through CGA1-mediated pathways. A Gα activated mutant, cga1Q204L was created to help establish the role of CGA1 in growth and development, and in mediating hydrophobin secretion and expression. The activated Gα allele was transformed into a cga1 mutant strain. The transgenic lines showed phenotypes resembling the null mutant in development, sporulation and hydrophobicity, indicating a possible role for CGA1 as a stabilizer of these traits. 展开更多
关键词 COCHLIOBOLUS constitutively ACTIVATED G-ALPHA Subunit G-PROTEIN Fungal Signal Transduction
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Analysis on Construction and Property of the Constitutively Desulfurization Engineered Strain
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作者 YU Zhi-jian CHEN Chuan-hong +1 位作者 LI Jiang HUANG De-juan 《Meteorological and Environmental Research》 2012年第8期53-57,共5页
[Objective] The research aimed to study construction and property of the constitutively desulfurization engineered strain. [Method] Des- ulfurization gene dszABC in Pseudomonas delafieldii R-8 strain was cloned into e... [Objective] The research aimed to study construction and property of the constitutively desulfurization engineered strain. [Method] Des- ulfurization gene dszABC in Pseudomonas delafieldii R-8 strain was cloned into expression vector pPR9TT with gap promoter to build a constitutive expression plasmid pRT-C. Then, pRT-C was reintroduced into R-8-0 strain to obtain constitutively engineered strain R-8-C. Moreover, its desulfu- rization property was studied. [ Result ] Strain R-8-C still had higher desulfurization activity in BSM medium with 0.10 mmol/L of Na2 SO4. Within 72 h, its desulfurization activity was 93% of the strain R-8 using DBT as the sole sulfur source, while control (strain R-8) nearly couldn't desulphate. When DBT was the sole sulfur source, in different growth periods, the desulfurization activity of strain R-8-C was all higher than that of the strain R-8. Within 24 h, its activity was 1.3 times of the strain R-8. [ Conclusion] These results were theoretically and technically helpful for understanding regulation mechanism of the desulfurization gene and constructing highly active desulphurization engineering strain. 展开更多
关键词 Bio-desulfurization P. delafieldii constitutively engineered strain DBT China
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Sphingosine 1-phosphate acts as an activator for the porcine Gpr3 of constitutively active G protein-coupled receptors 被引量:2
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作者 Bao-le ZHANG Ye LI +5 位作者 Jian-hua DING Fu-lu DONG Yan-jun HOU Bao-chun JIANG Fang-xiong SHI Yin-xue XU 《Journal of Zhejiang University-Science B(Biomedicine & Biotechnology)》 SCIE CAS CSCD 2012年第7期555-566,共12页
We cloned the complete coding sequences of porcine Gpr3, Gpr6, and Gpr12 genes. Further, on the basis of their high levels of sequence similarity, these genes are identified as a subfamily of G protein-coupled recepto... We cloned the complete coding sequences of porcine Gpr3, Gpr6, and Gpr12 genes. Further, on the basis of their high levels of sequence similarity, these genes are identified as a subfamily of G protein-coupled receptors. These putative protein sequences also showed high sequence identity with other mammalian orthologs, including several highly conserved motifs. A wide expression of the Gpr3 gene in pigs was observed through tissue distribution analysis by reverse transcriptase-polymerase chain reaction (RT-PCR) and real-time PCR, specially in the brain, pituitary, fat, liver and oocyte, where its strong expression was observed. The Gpr3 gene was found to be located on chromosome 6 and a single exon coded for the entire open reading frame. Expression of porcine Gpr3 in HEK293 cells resulted in constitutive activation of adenylate cyclase (AC) similar in amplitude to that produced by fully stimulated Gs coupled receptors. Moreover, sphingosine 1-phosphate (S1P) could increase AC activation via the constitutively active Gpr3 receptor. When a Gpr3-green fluorescent protein (GFP) construct was expressed in HEK293 cells, GFP-labeled Gpr3 protein was shown to be localized in the plasmalemma and subcellular membranes. After S1P treatment, agonist-mediated internalization could be visualized by confocal microscopy. In short, our findings suggest the porcine Gpr3, Gpr6, and Gpr12 genes as a subfamily of G protein-coupled receptors, and porcine Gpr3 was a constitutively active G protein-coupled receptor. Constitutive activation of AG and agonist-mediated internalization of Gpr3 receptor could be modulated by the S1 P, suggesting that S1P might act as an activator for porcine Gpr3 receptor. 展开更多
关键词 G protein-coupled receptor Constitutive activity Sphingosine 1-phosphate Receptor internalization Porcine Gpr3 Molecular cloning
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Constitutively Expressed αB—Crystallin in Heat Schock Transcription Factor 1 Knockout Mice Myocardium
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作者 刘莉 张洪慧 +3 位作者 丁国宪 程蕴琳 晏良军 BENJAMINIvorJ 《Journal of Nanjing Medical University》 2003年第2期67-73,共7页
Objective-To investigate the effects of heat shock transcription factor 1) gene on the constitutivety expressed αB-CrystaUin (aBC) in mice myocardium. Methods-The expression levels of constitutive aBC in HSF1 knockou... Objective-To investigate the effects of heat shock transcription factor 1) gene on the constitutivety expressed αB-CrystaUin (aBC) in mice myocardium. Methods-The expression levels of constitutive aBC in HSF1 knockout (hsf1 - /- ) and HSFl wild type (As/1 + /+) mice myocardium were evaluated by western blot and immunohistochemistry. Results : The αBC levels in hsfl -/- and hsfl +/+ were 68. 42±4. 16, 100. 00±7. 58, respectively (P<0. 05, cytoso-lic fraction) , and 20. 53±1. 01, 37. 55±1. 91, respectively (P<0. 05, pellet fraction). The aBC signals decreased significantly in hsfl -/- myocardium when compared with those in hsfl +/+ myocardium stained with fluorescence immunohistochemistry. Conclusion-HSF1 is an important, but not the only factor, which mediates the constitutively expressed aBC. 展开更多
关键词 heat shock transcription factor 1 gene CONSTITUTIVE αB-Crystallin KNOCKOUT gene expression
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Development and application of rock rheological constitutive model considering dynamic stress field and seepage field 被引量:2
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作者 Yian Chen Guangming Zhao +2 位作者 Wensong Xu Shoujian Peng Jiang Xu 《International Journal of Mining Science and Technology》 2025年第3期467-482,共16页
The generalized rheological tests on sandstone were conducted under both dynamic stress and seepage fields.The results demonstrate that the rheological strain of the specimen under increased stress conditions is great... The generalized rheological tests on sandstone were conducted under both dynamic stress and seepage fields.The results demonstrate that the rheological strain of the specimen under increased stress conditions is greater than that under creep conditions,indicating that the dynamic stress field significantly influences the rheological behaviours of sandstone.Following the rheological tests,the number of small pores in the sandstone decreased,while the number of medium-sized pores increased,forming new seepage channels.The high initial rheological stress accelerated fracture compression and the closure of seepage channels,resulting in reduction in the permeability of sandstone.Based on the principles of generalized rheology and the experimental findings,a novel rock rheological constitutive model incorporating both the dynamic stress field and seepage properties has been developed.Numerical simulations of surrounding rock deformation in geotechnical engineering were carried out using a secondary development version of this model,which confirmed the applicability of the generalized rheological numerical simulation method.These results provide theoretical support for the long-term stability evaluation of engineering rock masses and for predicting the deformation of surrounding rock. 展开更多
关键词 Generalized rheological test Seepage-stress coupling Seepage properties Dynamic stress field Rheological constitutive model
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Hot deformation behavior and microstructure evolution in premium GH4738 alloy 被引量:1
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作者 Min Guo Jun Zhao +2 位作者 Mai-cang Zhang Asad Ullah Hao Wang 《Journal of Iron and Steel Research International》 2025年第9期2947-2963,共17页
The hot deformation behavior of the premium GH4738 alloy was investigated in the temperature range of 1313 to 1353 K at strain rates of 0.01 to 1 s^(−1)using the hot compression test.To accurately predict flow stress,... The hot deformation behavior of the premium GH4738 alloy was investigated in the temperature range of 1313 to 1353 K at strain rates of 0.01 to 1 s^(−1)using the hot compression test.To accurately predict flow stress,three novel strain compensation constitutive equations were developed and rigorously assessed.The results indicate that the power function model(correlation coefficients r=0.98544)demonstrates greater prediction accuracy compared to other functions,with a calculated average activation energy of 507.968 kJ mol−1.Additionally,electron backscattered diffraction technology and transmission electron microscopy were used to analyze the evolution of the alloy microstructure during dynamic recrystallization under different deformation conditions.The results show that under high-temperature and large deformation conditions,the dislocation density and the degree of grain rotation increase,which promotes the formation and growth of new recrystallized grains,so that recrystallization is completed when the deformation amount reaches 30%.Besides,the increase in the temperature not only enhances the thermal activation mechanism,but also improves the grain size uniformity and texture consistency.Meanwhile,the carbide inhibits grain overgrowth by pinning grain boundaries,maintaining a fine and uniform grain structure of the alloy,and thereby improving the plasticity of the material. 展开更多
关键词 Premium GH4738 alloy Strain compensation constitutive equation Microstructure evolution Flow behavior Peak stress constitutive model
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Creep constitutive model for damaged soft rock based on fractional-order nonlinear theory 被引量:1
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作者 BAO Min ZHOU Zihan +1 位作者 CHEN Zhonghui ZHANG Lingfei 《Journal of Mountain Science》 2025年第6期2276-2290,共15页
Investigating the combined effects of mining damage and creep damage on slope stability is crucial,as it can comprehensively reveal the non-linear deformation characteristics of rock under their joint influence.This s... Investigating the combined effects of mining damage and creep damage on slope stability is crucial,as it can comprehensively reveal the non-linear deformation characteristics of rock under their joint influence.This study develops a fractional-order nonlinear creep constitutive model that incorporates the double damage effect and implements a non-linear creep subroutine for soft rock using the threedimensional finite difference method on the FLAC3D platform.Comparative analysis of the theoretical,numerical,and experimental results reveals that the fractional-order constitutive model,which incorporates the double damage effect,accurately reflects the distinct deformation stages of green mudstone during creep failure and effectively captures the non-linear deformation in the accelerated creep phase.The numerical results show a fitting accuracy exceeding 97%with the creep test curves,significantly outperforming the 61%accuracy of traditional creep models. 展开更多
关键词 Mining damage Creep damage FRACTIONAL-ORDER Constitutive model Secondary development
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Creep constitutive model of yellow sandstone under coupling action of unloading and wet-dry cyclic damage 被引量:1
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作者 QIN Zhe LIU Zhen +1 位作者 ZHANG Run-chang FU Hou-li 《Journal of Mountain Science》 2025年第3期1087-1100,共14页
The study focuses on the creep characteristics of significant yellow sandstone for water conservancy, hydropower, and other waterrelated slope excavation unloading rock-graded loading creep characteristics. It conduct... The study focuses on the creep characteristics of significant yellow sandstone for water conservancy, hydropower, and other waterrelated slope excavation unloading rock-graded loading creep characteristics. It conducts a uniaxial graded loading creep test on yellow sandstone under different pre-peak unloading and wetting-drying cycles. The improved nonlinear Nishihara model was obtained by introducing a nonlinear viscous element with an accelerated creep threshold switch. The sensitivity characteristics of the parameters of the improved creep model were analyzed and a nonlinear creep constitutive model was established, considering the unloading-cyclic intrinsic damage induced by water intrusion. The research results show that:(1)With an increase in the unloading point, the porosity of the rock samples initially decreases and then increases. As the number of cyclic water intrusions rises, the porosity of the rock samples gradually increases, reaching a maximum of 9.58% at an unloading point of 70% uniaxial compression stress(0.7 Rc) after five cycles.(2) Total creep deformation increases with the number of cyclic water intrusions;however, with an increase in the unloading ratio, the original samples show an initial decrease, followed by an increase in creep deformation. With a higher unloading ratio and various instances of cyclic water intrusion, the total creep time of the rock samples,compared to the original samples, is reduced by 21.8%and 23.02%. The creep damage mode gradually changes from shear damage to tensile damage.(3) The sensitivity characteristics of the improved creep model parameters show that transient elasticity modulus E1 is affected by the coupling of unloading and cyclic water intrusion. The viscoelastic modulus E2 and viscous coefficient η1 are mainly affected by unloading and cyclic water intrusion.(4) Based on the strain equivalence principle of damage mechanics, the damage treatment of the parameters in the original model is improved to construct a nonlinear creep constitutive model that considers unloading-cyclic water intrusion damage. A parameter inversion and comparison to the traditional Nishihara model reveal an average relative standard deviation of 0.271%,significantly less than 1%, indicating a more accurate nonlinear creep constitutive model. The research results are crucial for analyzing the long-term stability of water-related steep rocky slopes post-excavation and unloading and for preventing and controlling creep-type landslide disasters. 展开更多
关键词 Pre-peak unloading Dry and wet cycles Creep test Deformation characteristics Creep constitutive model
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Undrained mechanical behavior of unsaturated completely weathered granite:Experimental investigation and constitutive modeling 被引量:1
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作者 DU Shao-hua MA Jin-yin +2 位作者 RUAN Bo WU Gen-shui ZHANG Rui-chao 《Journal of Central South University》 2025年第6期2307-2327,共21页
The undrained mechanical behavior of unsaturated completely weathered granite(CWG)is highly susceptible to alterations in the hydraulic environment,particularly under uniaxial loading conditions,due to the unique natu... The undrained mechanical behavior of unsaturated completely weathered granite(CWG)is highly susceptible to alterations in the hydraulic environment,particularly under uniaxial loading conditions,due to the unique nature of this soil type.In this study,a series of unconfined compression tests were carried out on unsaturated CWG soil in an underground engineering site,and the effects of varying the environmental variables on the main undrained mechanical properties were analyzed.Based on the experimental results,a novel constitutive model was then established using the damage mechanics theory and the undetermined coefficient method.The results demonstrate that the curves of remolded CWG specimens with different moisture contents and dry densities exhibited diverse characteristics,including brittleness,significant softening,and ductility.As a typical indicator,the unconfined compression strength of soil specimens initially increased with an increase in moisture content and then decreased.Meanwhile,an optimal moisture content of approximately 10.5%could be observed,while a critical moisture content value of 13.0%was identified,beyond which the strength of the specimen decreases sharply.Moreover,the deformation and fracture of CWG specimens were predominantly caused by shear failure,and the ultimate failure modes were primarily influenced by moisture content rather than dry density.Furthermore,by comparing several similar models and the experimental data,the proposed model could accurately replicate the undrained mechanical characteristics of unsaturated CWG soil,and quantitatively describe the key mechanical indexes.These findings offer a valuable reference point for understanding the underlying mechanisms,anticipating potential risks,and implementing effective control measures in similar underground engineering projects. 展开更多
关键词 completely weathered granite undrained mechanical behavior environmental variable unconfined compression test constitutive model
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Mesoscopic fracture damage evolution and fractal damage constitutive model of heat-treated red sandstone under direct tensile impact loadings 被引量:1
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作者 Shi Liu Yu Jia +1 位作者 Yue Zhai Shaoxu Hao 《Journal of Rock Mechanics and Geotechnical Engineering》 2025年第1期323-340,共18页
Understanding the mesoscopic tensile fracture damage of rock is the basis of evaluating the deterioration process of mechanical properties of heat-damaged rock. For this, tensile tests of rocks under high-temperature ... Understanding the mesoscopic tensile fracture damage of rock is the basis of evaluating the deterioration process of mechanical properties of heat-damaged rock. For this, tensile tests of rocks under high-temperature treatment were conducted with a ϕ75 mm split Hopkinson tension bar (SHTB) to investigate the mesoscopic fracture and damage properties of rock. An improved scanning electron microscopy (SEM) experimental method was used to analyze the tensile fracture surfaces of rock samples. Qualitative and quantitative analyses were performed to assess evolution of mesoscopic damage of heat-damaged rock under tensile loading. A constitutive model describing the mesoscopic fractal damage under thermo-mechanical coupling was established. The results showed that the high temperatures significantly reduced the tensile strength and fracture surface roughness of the red sandstone. The three-dimensional (3D) reconstruction of the fracture surface of the samples that experienced tensile failure at 900 °C showed a flat surface. The standard deviation of elevation and slope angle of specimen fracture surface first increased and then decreased with increasing temperature. The threshold for brittle fracture of the heat-damaged red sandstone specimens was 600 °C. Beyond this threshold temperature, local ductile fracture occurred, resulting in plastic deformation of the fracture surface during tensile fracturing. With increase of temperature, the internal meso-structure of samples was strengthened slightly at first and then deteriorated gradually, which was consistent with the change of macroscopic mechanical properties of red sandstone. The mesoscopic characteristics, such as the number, mean side length, maximum area, porosity, and fractal dimension of crack, exhibited an initial decline, followed by a gradual increase. The development of microcracks in samples had significant influence on mesoscopic fractal dimension. The mesoscopic fractal characteristics were used to establish a mesoscopic fractal damage constitutive model for red sandstone, and the agreement between the theoretical and experimental results validated the proposed model. 展开更多
关键词 High temperature rock mechanics Dynamic direct tension Red sandstone Mesoscopic fracture mechanism Fractal damage constitutive model
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Flow Behavior and Dynamic Recrystallization Mechanism of CSS‑42L Bearing Steel During Hot Compression Deformation 被引量:1
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作者 Tianyi Zeng Zirui Luo +2 位作者 Hao Chen Wei Wang Ke Yang 《Acta Metallurgica Sinica(English Letters)》 2025年第3期465-480,共16页
In this work,fow behavior and dynamic recrystallization(DRX)mechanism of a low carbon martensitic stainless bearing steel,CSS-42L,were investigated using a thermomechanical simulator under the temperature and strain r... In this work,fow behavior and dynamic recrystallization(DRX)mechanism of a low carbon martensitic stainless bearing steel,CSS-42L,were investigated using a thermomechanical simulator under the temperature and strain rate ranges of 900 to 1100℃ and 0.1 to 20 s^(−1),respectively.The Arrhenius-type constitutive equation was established based on the fow stress curves.Moreover,the peak stress decreased with the increase in deformation temperature and the decrease in strain rate.There were two DRX mechanisms during hot deformation of the current studied steel,the main one being discontinuous dynamic recrystallization mechanism,acting through grain boundary bulging and migration,and the auxiliary one being continuous dynamic recrystallization mechanism,working through the rotation of sub-grains.On the basis of microstructural characterizations,power dissipation maps and fow instability maps,the optimized hot deformation parameters for CSS-42L bearing steel were determined as 1050℃/0.1 s^(−1) and 1100℃/1 s^(−1). 展开更多
关键词 CSS-42L bearing steel Hot deformation Flow stress Constitutive equation Discontinuous dynamic recrystallization Continuous dynamic recrystallization
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A novel constitutive model for two-stage creep aging process of 7B50 aluminum alloy and its application in springback prediction 被引量:1
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作者 Ling-zhi XU Can-yu TONG +7 位作者 Chang-zhi LIU Li-hua ZHAN Ming-hui HUANG You-liang YANG Dong-yang YAN Jian-hua YIN Hui XIA Yong-qian XU 《Transactions of Nonferrous Metals Society of China》 2025年第3期734-748,共15页
A new unified constitutive model was developed to predict the two-stage creep-aging(TSCA)behavior of Al-Zn-Mg-Cu alloys.The particular bimodal precipitation feature was analyzed and modeled by considering the primary ... A new unified constitutive model was developed to predict the two-stage creep-aging(TSCA)behavior of Al-Zn-Mg-Cu alloys.The particular bimodal precipitation feature was analyzed and modeled by considering the primary micro-variables evolution at different temperatures and their interaction.The dislocation density was incorporated into the model to capture the effect of creep deformation on precipitation.Quantitative transmission electron microscopy and experimental data obtained from a previous study were used to calibrate the model.Subsequently,the developed constitutive model was implemented in the finite element(FE)software ABAQUS via the user subroutines for TSCA process simulation and the springback prediction of an integral panel.A TSCA test was performed.The result shows that the maximum radius deviation between the formed plate and the simulation results is less than 0.4 mm,thus validating the effectiveness of the developed constitutive model and FE model. 展开更多
关键词 two-stage creep aging process bimodal precipitation constitutive modeling springback prediction Al−Zn−Mg−Cu alloy
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Breaking barriers: MS-BDF tools in the quality control of insect-derived traditional Chinese medicine 被引量:1
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作者 Caixia Yuan Dandan Zhang +2 位作者 Hairong Zhang Jiyang Dong Caisheng Wu 《Journal of Pharmaceutical Analysis》 2025年第6期1403-1405,共3页
Insect-derived traditional Chinese medicine(TCM)constitutes an essential component of TCM,with the earliest records found in“52 Bingfang”(Prescriptions of fifty-two diseases,which is one of the earliest Chinese medi... Insect-derived traditional Chinese medicine(TCM)constitutes an essential component of TCM,with the earliest records found in“52 Bingfang”(Prescriptions of fifty-two diseases,which is one of the earliest Chinese medical prescriptions). 展开更多
关键词 traditional chinese medicine tcm constitutes chinese medical prescriptions prescriptions fifty two diseases ms bdf tools insect derived traditional chinese medicine quality control breaking barriers TCM
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Hot Deformation Characteristics of Fe-Cr-Ni-based Alloys in Advanced Nuclear Applications
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作者 Yang Han Li Bo +4 位作者 Lu Jinwei Xu Long Chen Wanqing Zhou Wei Du Yong 《稀有金属材料与工程》 北大核心 2025年第5期1134-1144,共11页
Thermal deformation characteristics of Fe-Cr-Ni-based alloys for nuclear power plants were investigated using a Gleeble3500 thermal simulation tester.The microstructure evolution law of alloy heat deformation was inve... Thermal deformation characteristics of Fe-Cr-Ni-based alloys for nuclear power plants were investigated using a Gleeble3500 thermal simulation tester.The microstructure evolution law of alloy heat deformation was investigated using the electron backscatter diffraction(EBSD)technique.Results demonstrate that the flow stress curves show typical dynamic recrystallization(DRX)characteristics.According to EBSD analysis,the nucleation and growth of DRX grains are mainly at grain boundaries.The complete DRX occurs at 1100℃/0.01 s^(−1) condition,and the grains are refined.The main DRX nucleation mechanism of the alloy is the grain boundary bowing nucleation.Therefore,the softening mechanism of Fe-Cr-Ni-based alloys for nuclear power plants is the combination of dynamic recovery and DRX.The Arrhenius constitutive model with strain compensation is developed.The correlation coefficient between the predicted and experimental values is 0.9947.The reliable mathematical model of critical stress(strain)and Z parameter is obtained.The critical stress(strain)of DRX increases as the temperature decreases or the strain rate increases.The DRX kinetic model is established by the Avrami model,and a typical S-type curve is obtained.As the strain rate decreases and the temperature increases,the volume fraction of DRX increases. 展开更多
关键词 Fe-Cr-Ni-based alloy EBSD constitutive equation DRX
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Hot Deformation Behavior and Microstructure Evolution of Electrolytic Copper
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作者 Zhang Han Sang Chen +3 位作者 Zhang Yan Xu Yangtao Qiao Jisen Xia Tiandong 《稀有金属材料与工程》 北大核心 2025年第4期920-929,共10页
The hot deformation behavior of electrolytic copper was investigated using a Gleeble-3500 thermal simulation testing machine at temperatures ranging from 500℃ to 800℃ and strain rates ranging from 0.01 s^(-1) to 10 ... The hot deformation behavior of electrolytic copper was investigated using a Gleeble-3500 thermal simulation testing machine at temperatures ranging from 500℃ to 800℃ and strain rates ranging from 0.01 s^(-1) to 10 s^(-1),under 70% deformation conditions.The true stress-true strain curves were analyzed and a constitutive equation was established at a strain of 0.5.Based on the dynamic material model proposed by Prasad,processing maps were developed under different strain conditions.Microstructure of compressed sample was observed by electron backscatter diffraction.The results reveal that the electrolytic copper demonstrates high sensitivity to deformation temperature and strain rate during high-temperature plastic deformation.The flow stress decreases gradually with raising the temperature and reducing the strain rate.According to the established processing map,the optimal processing conditions are determined as follows:deformation temperatures of 600-650℃ and strain rates of 5-10 s^(-1).Discontinuous dynamic recrystallization of electrolytic copper occurs during high-temperature plastic deformation,and the grains are significantly refined at low temperature and high strain rate conditions. 展开更多
关键词 electrolytic copper hot deformation constitutive equation dynamic recrystallization
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Hot Deformation Behavior and Processing Map of Zr-Sn-Nb-Fe-Cr Alloy
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作者 Li Yuli Li Hao +3 位作者 Chen Qiuyu Zhou Xuan Ma Tianyang Sun Taotao 《稀有金属材料与工程》 北大核心 2025年第7期1671-1677,共7页
The hot deformation characteristics of induction quenched Zr-Sn-Nb-Fe-Cr alloy forged rod in the temperature range of 600–900°C and strain rate range of 0.001–1 s^(-1)were studied by Gleeble3800 uniaxial hot co... The hot deformation characteristics of induction quenched Zr-Sn-Nb-Fe-Cr alloy forged rod in the temperature range of 600–900°C and strain rate range of 0.001–1 s^(-1)were studied by Gleeble3800 uniaxial hot compression experiment.The results show that the flow stress decreases with the decrease in strain rate and the increase in deformation temperature in the true stress-true strain curve of Zr-Sn-Nb-Fe-Cr alloy forged rod.Moreover,the hot deformation characteristics of the material can be described by the hyperbolic sine constitutive equation.Under the experimental conditions,the average thermal activation energy(Q)of the alloy was 412.9105 kJ/mol.The microstructure analysis of the processing map and the sample after hot compression shows that the optimum hot working parameters of the alloy are 795–900°C,0.001–0.0068 s^(-1),at the deformation temperature of 600–900°C,and the strain rate of 0.001–1 s^(-1). 展开更多
关键词 zirconium alloy constitutive equation hot deformation processing map
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Constitutive Model and Microstructure Evolution of Asextruded Ti-6554 Alloy Based on Temperature Rise Correction
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作者 Li Changmin Luo Hengjun +6 位作者 Zhao Ning Guo Shiqi Wei Minggang Xiang Wei Cui Mingliang Xie Jing Huang Liang 《稀有金属材料与工程》 北大核心 2025年第9期2189-2198,共10页
The hot deformation behavior of as-extruded Ti-6554 alloy was investigated through isothermal compression at 700–950°C and 0.001–1 s^(−1).The temperature rise under different deformation conditions was calculat... The hot deformation behavior of as-extruded Ti-6554 alloy was investigated through isothermal compression at 700–950°C and 0.001–1 s^(−1).The temperature rise under different deformation conditions was calculated,and the curve was corrected.The strain compensation constitutive model of as-extruded Ti-6554 alloy based on temperature rise correction was established.The microstructure evolution under different conditions was analyzed,and the dynamic recrystallization(DRX)mechanism was revealed.The results show that the flow stress decreases with the increase in strain rate and the decrease in deformation temperature.The deformation temperature rise gradually increases with the increase in strain rate and the decrease in deformation temperature.At 700°C/1 s^(−1),the temperature rise reaches 100°C.The corrected curve value is higher than the measured value,and the strain compensation constitutive model has high prediction accuracy.The precipitation of theαphase occurs during deformation in the twophase region,which promotes DRX process of theβphase.At low strain rate,the volume fraction of dynamic recrystallization increases with the increase in deformation temperature.DRX mechanism includes continuous DRX and discontinuous DRX. 展开更多
关键词 as-extruded Ti-6554 alloy temperature rise correction constitutive model microstructure evolution
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Dynamic behavior of a battery pack based on single reference impact testing of a secondary cell
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作者 Zhen Xiao Wen-rong Fan Wei-song Hu 《中国科学技术大学学报》 北大核心 2025年第2期44-50,43,I0002,共9页
The mechanical properties of secondary cells are crucial to the safety and reliability of battery packs,which can fail due to extrusion and vibration in a vehicle crash.To analyze the structural response of the second... The mechanical properties of secondary cells are crucial to the safety and reliability of battery packs,which can fail due to extrusion and vibration in a vehicle crash.To analyze the structural response of the secondary cell and its other dynamic behaviors,the experiment and some numerical simulations were carried out based on single reference impact testing.Then,an equivalent constitutive relationship of the secondary cell was proposed to reveal the dynamic properties and used to guide the safety estimation of the battery pack.As the input parameter to the finite element model,the equivalent constitutive relationship,including but not limited to the elastic modulus and stain-stress curve,determines the simulation precision of the battery packs.Compared to the experimental results of the natural frequency of the battery pack,the simulation error is below 2%when the elastic modulus of the secondary cell in the battery pack has been verified. 展开更多
关键词 equivalent constitutive relationship secondary cell dynamic property
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Mechanical Constitutive Model for Equivalent Solid of Fission Gas Bubbles in Irradiated U-10Mo Fuels
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作者 Li Yong Yan Feng +2 位作者 Zhang Jing Zang Liye Ding Shurong 《稀有金属材料与工程》 北大核心 2025年第7期1653-1660,共8页
The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclea... The internal pressure within fission gas bubbles(FGBs)in irradiated nuclear fuels drives mechanical interactions with the surrounding fuel skeleton.To investigate the micromechanical stress fields in irradiated nuclear fuels containing pressurized FGBs,a mechanical constitutive model for the equivalent solid of FGBs was developed and validated.This model was based on the modified Van der Waals equation,incorporating the effects of surface tension.Using this model,the micromechanical fields in irradiated U-10Mo fuels with randomly distributed FGBs were calculated during uniaxial tensile testing via the finite element(FE)method.The macroscopic elastic constants of the irradiated U-10Mo fuels were then derived using homogenization theory,and the influences of bubble pressure,bubble size,and porosity on these constants were examined.Results show that adjacent FGBs exhibit mechanical interactions,which leads to distinct stress concentrations in the surrounding fuel skeleton.The macroscopic elastic constants of irradiated U-10Mo fuels decrease with increasing the macroscopic porosity,which can be quantitatively described by the Mori-Tanaka model.In contrast,bubble pressure and size have negligible effects on these constants. 展开更多
关键词 effective mechanical constitutive model fission gas bubbles FE method U-10Mo nuclear fuels macroscopic elastic constants
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Gut microbial characteristics of the damp-heat constitution:a population-based multicenter cross-sectional study
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作者 LI Tianxing ZHU Linghui +9 位作者 WANG Xueke TANG Jun YANG Lingling PANG Guoming LI Huang WANG Liying DONG Yang ZHAO Shipeng LI Yingshuai LI Lingru 《Journal of Traditional Chinese Medicine》 2025年第1期140-151,共12页
OBJECTIVE:To investigate the difference in gut microbiota between population with damp-heat constitution(DHC)and balanced constitution(BC).METHODS:A multi-centered cross-sectional casecontrol study was conducted,which... OBJECTIVE:To investigate the difference in gut microbiota between population with damp-heat constitution(DHC)and balanced constitution(BC).METHODS:A multi-centered cross-sectional casecontrol study was conducted,which included 249 participants with damp-heat constitution or balanced constitution.Baseline information of participants was collected,and stool samples were collected for gut microbiota analysis.Principal coordinate analysis,linear discriminant analysis effect size analysis,receiver operating characteristic,random forest model,and phylogenetic investigation of communities by reconstruction of unobserved states methods were used to reveal the relationship between gut microbiota and the damp-heat constitution.RESULTS:Compared to those in the BC group,the richness and diversity of the microbiota,specifically those of several short-chain fatty acid producing genera such as Barnesiella,Coprobacter,and Butyricimonas,were significantly decreased in the DHC group.Regarding biological functions,flavonoid biosynthesis,propanoate metabolism,and nucleotide sugar metabolism were suppressed,while arachidonic acid metabolism and glutathione metabolism were enriched in the DHC group.Finally,a classifier based on the microbiota was constructed to discriminate between the DHC and BC populations.CONCLUSION:The gut microbiota of the DHC population exhibits significantly reduced diversity and is closely related to inflammation,metabolic disorders,and liver steatosis,which is consistent with clinical observations,thus serving as a potential diagnostic tool for traditional Chinese medicine constitution discrimination. 展开更多
关键词 damp-heat constitution balanced constitution Traditional Chinese medicine constitution MICROBIOTA inflammatory PICRUSt multicenter study cross-sectional studies
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