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Influence of layer thickness on formation quality,microstructure,mechanical properties,and corrosion resistance of WE43 magnesium alloy fabricated by laser powder bed fusion

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Journal of Magnesium and Alloys 2024年第4期12卷 1367-1385页

作者： Bangzhao Yin Jinge Liu bo peng Mengran Zhou Bingchuan Liu Xiaolin Ma Caimei Wang peng Wen Yun Tian Yufeng Zheng State Key Laboratory of Tribology in Advanced Equipment Beijing100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Institute for Precision Medicine Tsinghua UniversityBeijing102218China Department of Orthopaedics Peking University Third HospitalBeijing 100191China Beijing AKEC Medical Co. Ltd.Beijing 102200China School of Materials Science and Engineering Peking UniversityBeijing 100871China Engineering Research Center of bone and Joint Precision Medicine Ministry of EducationBeijing 100191China

Laser powder bed fusion(L-PBF)of Mg alloys has provided tremendous opportunities for customized production of aeronautical and medical *** thickness(LT)is of great significance to the L-PBF process but has not been studied for Mg *** this study,WE43 Mg alloy bulk cubes,porous scaffolds,and thin walls with layer thicknesses of 10,20,30,and 40μm were *** required laser energy input increased with increasing layer thickness and was different for the bulk cubes and porous *** tended to occur at the connection joints in porous scaffolds for LT40 and could be eliminated by reducing the laser energy *** thin wall parts,a large overhang angle or a small wall thickness resulted in porosity when a large layer thicknesses was used,and the porosity disappeared by reducing the layer thickness or laser energy input.A deeper keyhole penetration was found in all occasions with porosity,explaining the influence of layer thickness,geometrical structure,and laser energy input on the *** the samples achieved a high fusion quality with a relative density of over 99.5%using the optimized laser energy *** increased layer thickness resulted to more precipitation phases,finer grain sizes and decreased grain *** the similar high fusion quality,the tensile strength and elongation of bulk samples were significantly improved from 257 MPa and 1.41%with the 10μm layer to 287 MPa and 15.12%with the 40μm layer,in accordance with the microstructural *** effect of layer thickness on the compressive properties of porous scaffolds was ***,the corrosion rate of bulk samples accelerated with increasing the layer thickness,mainly attributed to the increased number of precipitation phases.

关键词： Magnesium alloy WE43 Laser powder bed fusion Layer thickness Process optimization

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Isospin-sensitive observables as a probe of proton transition momentum in the HMT

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Chinese Physics C 2019年第11期43卷 106-111页

作者： Fang Zhang Hai-bo peng Jiang-Tao Zhao School of Nuclear Science and Technology Lanzhou UniversityLanzhou 730000China

Based on the IBUU transport model, the effect of proton transition momentum on collective flows is studied in ^40Ca + ^40Ca,^112Sn + ^112Sn, and ^197Au + ^197Au collisions at an incident beam energy of 400 MeV/A with impact parameter b=6 fm. It is found that in a neutron rich system, the difference between neutron and proton elliptic flow is largely affected by the proton transition momentum. At beam energies around (and particularly below) the pion production threshold, the π^-/π^+ ratio is greatly sensitive to proton transition momentum in asymmetric nuclear matter. This study may help us to understand the nucleon momentum distribution in nuclei, which is important for the equation of state of asymmetric nuclear matter, such as neutron stars.

关键词： heavy ion collisions short range correlation collective flow charged pion production

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Improving corrosion resistance of additively manufactured WE43 magnesium alloy by high temperature oxidation for biodegradable applications

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Journal of Magnesium and Alloys 2024年第3期12卷 940-953页

作者： Jinge Liu Bangzhao Yin Fei Song Bingchuan Liu bo peng peng Wen Yun Tian Yufeng Zheng Xiaolin Ma Caimei Wang State Key Laboratory of Tribology in Advanced Equipment Beijing100084China Department of Mechanical Engineering Tsinghua UniversityBeijing 100084China Department of Orthopaedics Beijing Tsinghua Changgung HospitalInstitute for Precision MedicineTsinghua UniversityBeijing102218China Department of Orthopaedics Peking University Third HospitalBeijing 100191China Engineering Research Center of bone and Joint Precision Medicine Ministry of EducationBeijing 100191China School of Materials Science and Engineering Peking UniversityBeijing 100871China Beijing AKEC Medical Co. Ltd.Beijing 102200China

Laser powder bed fusion(L-PBF)has been employed to additively manufacture WE43 magnesium(Mg)alloy biodegradable implants,but WE43 L-PBF samples exhibit excessively rapid *** this work,dense WE43 L-PBF samples were built with the relativity density reaching 99.9%.High temperature oxidation was performed on the L-PBF samples in circulating air via various heating temperatures and holding *** oxidation and diffusion at the elevated temperature generated a gradient structure composed of an oxide layer at the surface,a transition layer in the middle and the *** oxide layer consisted of rare earth(RE)oxides,and became dense and thick with increasing the holding *** matrix was composed ofα-Mg,RE oxides and Mg_(24)RE_(5) *** precipitates almost disappeared in the transition *** passivation effect was observed in the samples treated by a suitable high temperature *** original L-PBF samples lost 40%weight after 3-day immersion in Hank’s solution,and broke into fragments after 7-day *** casted and solution treated samples lost roughly half of the weight after 28-day *** high temperature oxidation samples,which were heated at 525℃ for 8 h,kept the structural integrity,and lost only 6.88%weight after 28-day *** substantially improved corrosion resistance was contributed to the gradient structure at the *** one hand,the outmost dense layer of RE oxides isolated the corrosive medium;on the other hand,the transition layer considerably inhibited the corrosion owing to the lack of ***,high temperature oxidation provides an efficient,economic and safe approach to inhibit the corrosion of WE43 L-PBF samples,and has promising prospects for future clinical applications.

关键词： Laser powder bed fusion Biodegradable magnesium alloy High temperature oxidation Corrosion resistance WE43.

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Identification of quantitative trait loci for growth traits in red swamp crayfish(Procambarus clarkii)

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Aquaculture and Fisheries 2023年第6期8卷 727-736页

作者： Junxiao Sun Cuirong Luo bo peng Guohui peng Yunfei Tan Xufeng Bai National Key Laboratory of Crop Genetic Improvement Shuangshui ShuanglüInstituteHuazhong Agricultural UniversityWuhan430070China Hubei Hongshan Laboratory Wuhan430070China College of Fisheries Huazhong Agricultural UniversityWuhan430070China College of Life Science and Technology Huazhong Agricultural UniversityWuhan430070China Engineering Research Center of Green Development for Conventional Aquatic Biological Industry in the Yangtze River Economic Belt Ministry of EducationWuhan430070China

Genetic breeding is an important approach to improve the economic traits of aquaculture ***,the genetic basis for important economic traits of red swamp crayfish,including growth-related traits,has not yet been *** the present study,two full-sib families and two natural populations were employed to identify quantitative trait loci(QTLs)for growth-related traits of red swamp *** total,28 QTLs for five growth-related traits,including body weight,body length,carapace length,carapace width,and abdomen length,were repeatedly identified in more than two families/populations,by means of association analysis;nine of these displayed a heterosis *** phenotypic variations of the five investigated traits explained by the 28 QTLs ranged from 4.2%to 19.0%.Eight additive and three heterosis QTLs were further successfully validated using comparative analysis of favoured alleles between the small and big size crayfish groups in the natural *** conclusion,this study investigated the genetic basis of growth-related traits in red swamp crayfish,which is of great significance for their application in the future molecular breeding of the species.

关键词： Red swamp crayfish(Procambarus clarkii) Growth-related traits Simple sequence repeats Association analysis Quantitative trait loci

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Experimental Investigation of Multi-Mode Vortex-Induced Vibration of Flexible Risers with Different Mass Ratios

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China Ocean Engineering 2023年第1期37卷 1-15页

作者： WANG Yu LOU Min REN Xiao-hui LIANG Wei-xing LI Xiang DANG peng-bo School of Petroleum Engineering China University of Petroleum(East China)Qingdao 266580China Key Laboratory of Unconventional Oil&Gas Development(China University of Petroleum(East China)) Ministry of EducationQingdao 266580China College of Civil Engineering and Architecture Shandong University of Science and TechnologyQingdao 266590China

Experiments were conducted on risers with different mass ratios to study the effect of mode conversion and spanwise correlation. The slenderness ratio of the riser model was set as 169, and the Reynolds numbers are 1600-14400. The dynamic responses of riser models versus reduced velocity were analyzed, and the spanwise displacement, frequency,and trajectory of the mode conversion from the lower to the higher mode were explored. The results revealed that the riser model with a higher mass ratio excites a higher number of modes. The conversion region of multi-mode competition exists and narrows with the increasing mass ratio. Mode conversion is continuous and manifests as the transmission of peaks and troughs in mode shape: the peaks and troughs of mode shape move up in the mode stable development region and move down in the mode conversion region. The single-mode dominating vibration exhibits a standing wave feature, and the traveling wave feature is significant in the mode conversion region. Furthermore, the frequency jump is always transmitted from the trough to the peak of the mode shape, and finally, all the axial positions vibrate at the same frequency. The trajectory in the mode conversion region deviates from the 8-shape and recovers the standard8-shape at the middle and late stages of the mode stable development region.

关键词： vortex-induced vibration dynamic response mode conversion mass ratio mode weight

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Increased hippocampal Disrupted-In-Schizophrenia 1 expression in mice exposed prenatally to lead

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Neural Regeneration Research 2012年第25期7卷 1939-1945页

作者： Yuanyuan You Liguang Sun bo peng Yan Li Songbin Ben Shuang Gao Department of Biochemical and Molecular Biology China Medical University Shenyang 110001 Liaoning Province China Outpatient Department of China Medical University Shenyang 110001 Liaoning Province China Department of Biochemical and Molecular Biology Jilin Medical College Jilin 132013 Jilin Province China School of Life Science Liaoning University Shenyang 110036 Liaoning Province China School of Public Health China Medical University Shenyang 110001 Liaoning Province China

Disrupted-in-Schizophrenia 1 is a susceptibility gene for schizophrenia and other psychiatric disorders. Developmental lead exposure can cause neurological disorders similar to hyperactivity disorder, dyslexia and schizophrenia. In the present study, we examined the impact of developmental lead exposure, administered in vitro and in vivo, on hippocampal Disrupted-In- Schizophrenia 1 expression. Our results show that in cultured hippocampal neurons, in vitro exposure to 0.1-10 pM lead, inhibited neurite growth and increased Disrupted-In-Schizophrenia 1 mRNA and protein expression dose-dependently. In addition, blood lead levels in mice were increased with increasing mouse maternal lead （0.01-1 mM） exposure. Hippocampal neurons from these mice showed a concomitant increase in Disrupted-in-Schizophrenia 1 mRNA and protein expression. Overall our findings suggest that in vivo and in vitro lead exposure increases Disrupted-In-Schizophrenia 1 expression in hippocampal neurons dose-dependently, and consequently may influence synapse formation in newborn neurons.

关键词： lead exposure Disrupted-In-Schizophrenia 1 hippocampus neuron neurotoxicity synapse neuralregeneration

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Inclusions for Ultra-pure Ferritic Stainless Steels Containing 21% Chromium

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Journal of Iron and Steel Research International 2013年第10期20卷 70-74页

作者： WANG Hong-po SUN Li-feng peng bo JIANG Mao-fa College of Materials and Metallurgy Northeastern University

As stabilizing elements added into ultra-pure ferritic stainless steels, niobium and titanium react with car- bon and nitrogen to form carbonitrides and have great effects on the ratio of equiaxed zone and the grain size of solidi- fication structure of ingots, which remarkably affect the quality of cold-rolled sheets. Combined with thermodynamic calculation, style and precipitation progress of inclusions in ultra-pure ferritic stainless steels were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy and energy dispersive spectros- copy. The results indicate that the inclusions are mainly Ti-Al-N- O system inclusions in ultra-pure ferritic stainless steels. Al2Oa starts to precipitate firstly and then TiOx and TiN precipitates sequently. The inclusions are mainly single TiN particles and complex inclusions with Al2O3-Ti2O3 as cores and covered with TiN under the condition of 0.31% titanium addition and mainly Al2O3 under the condition of 0.01% titanium addition. A few （Nb,Ti）N parti- cles precipitate because of no enough titanium to react with nitrogen when titanium addition is 0.01 %. In addition, fine Nb（C, N） particles with size of less than 500 nm precipitate at relatively low temperature.

关键词： ultra-pure ferritic stainless steel ingot inclusion stabilizing element

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A BiGRU joint optimized attention network for recognition of drilling conditions

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Petroleum Science 2023年第6期20卷 3624-3637页

作者： Ying Qiao Hong-Min Xu Wen-Jun Zhou bo peng Bin Hu Xiao Guo National Key Laboratory of Oil and Gas Reservoir Geology and Exploitation Southwest Petroleum UniversityChengdu610500SichuanChina School of Computer Science Southwest Petroleum UniversityChengdu610500SichuanChina Information Management Center of Sinopec Southwest Oil and Gas Branch Chengdu610500SichuanChina

The identification and recording of drilling conditions are crucial for ensuring drilling safety and efficiency. However, the traditional approach of relying on the subjective determination of drilling masters based on experience formulas is slow and not suitable for rapid drilling. In this paper, we propose a drilling condition classification method based on a neural network model. The model uses an improved Bidirectional Gated Recurrent Unit (BiGRU) combined with an attention mechanism to accurately classify seven common drilling conditions simultaneously, achieving an average accuracy of 91.63%. The model also demonstrates excellent generalization ability, real-time performance, and accuracy, making it suitable for actual production. Additionally, the model has excellent expandability, which enhances its potential for further application.

关键词： Drilling condition classification BiGRU Machine learning Attention mechanism

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Inverse kinematics model of parallel macro-micro manipulator system

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Chinese Science Bulletin 2000年第24期45卷 2221-2226页

作者： WANG Wenli DUAN Baoyan LIU Hong NAN Rendong peng bo School of Mechanical and Electronic Engineering Xidian UniversityXi’an 710071China Beijing Astronomy Observatory China Academy of SciencesBeijing 100012China

An improved design, which employs the integration of optic, mechanical and electronic technologies for the next generation large radio telescope, is presented in this note. The authors propose the concept of parallel macro-micro manipulator system from the feed support structure with a rough tuning subsystem based on a cable structure and a fine tuning subsystem based on the Stewart platform. According to the requirement of astronomical observation, the inverse kinematics model of this parallel macro-micro manipulator system is deduced. This inverse kinematics model is necessary for the computer-controlled motion of feed.

关键词： large radio telescope parallel manipulator kinematics.

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Synthesis, Crystal Structure and Optical Properties of Europium Trifluoroacetate Complexes with 1,10-Phenanthroline and 2,2＇-Bipyridine

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Chinese Journal of Chemistry 2011年第2期29卷 267-272页

作者： She Jiangbo Cui Xiaoxia Hou Chaoqi Gao Chao Wei Wei peng bo State Key Laboratory of Transient Optics and Photonics Xi'an Institute of Optics and Precision Mechanics Chi- nese Academy of Science (CAS) Xi'an Shaanxi 710119 China Institute of Advanced Materials Nanjing University of Posts and Telecommunications Nanjing Jiangsu 210003 China

Two europium trifluoroacetate complexes, Eu（CF3COO）*** （1） and Eu（CF3COO）3·bpy （2）（where phen= 1,10-phenanthroline, bpy=2,2＇-bipyridine）, were synthesized and characterized by elemental analysis, Fourier transform infrared spectroscopy （FT-IR）, photoluminescence （PL） spectroscopy and thermogravimetric analysis （TA）. Single-crystal X-ray structure has been determined for the complex [Eu2（CF3COO）6·（phen）3·（H2O）2]·EtOH. The crystal structure of [Eu2（CF3COO）6·（phen）3·（H2O）2]·EtOH shows that two different coordination styles with europium ions coexist in the same crystal and have entirely different coordination geometries and numbers. This crystal can be considered as an 1 ： 1 adduct of [Eu（CF3COO）3·（Phen）2·H2O]·EtOH （9-coordination part） and Eu（CF3COO）3·phen·H2O （8-coordination part）. The excitation spectra of the two complexes demonstrate that the energy collected by ＂antenna ligands＂ is transferred to Eu3＋ ions efficiently. The room-temperature PL spectra of the complexes are composed of the typical Eu3＋ ions red emission, due to transitions between 5D0→7FJ（J=0→4）. The lifetimes of 5D0 of Eu3＋ in the complexes were examined using time-resolved spectroscopic analysis, and the life- time values of Eu（CF3COO）3·phen and Eu（CF3COO）3·bpy were fitting with bi-exponential （2987 and 353 us） and monoexponential （3191 us） curves, respectively. In order to elucidate the energy transfer process of the europium complexes, the energy levels of the relevant electronic states had been estimated. The thermal analyses indicate that they are all quite stable to heat.

关键词： europium complex luminescent property Judd-Ofelt theory thermal decomposition structure elucidation lanthanides

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