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Analysis on clogging of submerged entry nozzle in continuous casting of high strength steel with rare earth

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Journal of Iron and Steel Research International 2022年第1期29卷 34-43页

作者： Wei Liang Jing Li Bin Lu jian-guo zhi Shuai Zhang Yang liu State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Inner Mongolia Baotou Steel Union Co. Ltd.Baotou 014010Inner MongoliaChina

The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied based on the plant trials and thermodynamic *** was found that Ce_(2)O_(3) and CeAlO_(3) in tundish molten steel were transformed into Ce_(2)O_(2)S+CaO-Al_(2)O_(3) with the size of 2-3 lm during *** the flow velocity of molten steel on surface of the SEN was slow due to the boundary layer effect,Ce_(2)O_(3) inclusion in molten steel reacted with Al_(2)O_(3) in the SEN refractory to form *** the continuous erosion of molten steel and reaction,the compositions of CeAlO_(3),Al_(2)O_(3) and CaO were aggregated,and the clogging layers with different zones were formed on surface of the ***,a small amount of molten steel remaining in the arc zone and corner zone of the SEN formed solidified *** calcium treatment is canceled,the reaction probability between inclusions in molten steel and refractory should be reduced by improving the material and shape of the SEN.

关键词： Rare earth inclusion Tundish Submerged entry nozzle Clogging Thermodynamic calculation

Microstructure and microhardness of directionally solidified NiAl-W eutectic alloy

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Rare Metals 2020年第10期39卷 1174-1180页

作者： jian-Jun Gao zhi-Long Zhao Lu-Feng Wei Kai Cui Lin liu School of Mechanical Engineering and Automation Fuzhou UniversityFuzhou 350108China School of Mechanical Engineering Northwestern Polytechnical UniversityXi'an 710072China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi'an 710072China

The microstructure and microhardness of directionally solidified NiAl-W eutectic alloys at growth rates of 2-25μm·s^-1 were investigated by a Bridgman crystal growing facility at a temperature gradient of 300 K·cm^-*** view of the competitive growth between W dendritic and eutectic phases,W dendritic phase was eliminated,whereas the fully eutectic phase was prominent in the steady progress of the directionally solidified NiAl-W eutectic *** the growth rate(V)increased,both the structure and solid/liquid interface of the directionally solidified NiAl-W eutectic alloys changed from planar to *** the fibrous spacing(d)and the diameter(a)decreased with increase in growth rate(V).The Vickers microhardness(H)of the directionally solidified NiAl-W eutectic alloys decreased with fibrous spacing(d)or diameter(a)*** relationships of H to d and a were H=371.58 d^(-0.09)and H=297.70 a^(-0.09),respectively.

关键词： Microstructure Directional solidification Eutectic alloy Microhardness

Parasitoid wasps as effective biological control agents

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Journal of Integrative Agriculture 2019年第4期18卷 705-715页

作者： WANG zhi-zhi liu Yin-quan SHI Min HUANG jian-hua CHEN Xue-xin Ministry of Agriculture Key Lab of Molecular Biology of Crop Pathogens and Insects Zhejiang University State Key Lab of Rice Biology Zhejiang University Institute of Insect Sciences Zhejiang University

Biological control(biocontrol) is a safe, sustainable approach that takes advantage of natural enemies such as predators, parasitic insects or pathogens to manage pests in agroecosystems. Parasitoid wasps, a very large evolutionary group of hymenopteran insects, are well-known biological control agents for arthropod pests in agricultural and forest ecosystems. Here, we summarize the recent progress on the application of parasitoid wasps in biocontrol in China for the last five years. These include species diversity of parasitoid wasps, identification of dominant parasitoid wasps associated with insect pests and biocontrol practices(three types of biological control, i.e., classical, augmentative and conservation biological control) in several Chinese agroecosystems. We then treat different mass-rearing and release technologies and the commercialization of several parasitoid wasp species. We also summarize other work that may have a potential use in biocontrol, including the effect of plant volatiles on parasitoids and recent advance in the molecular mechanisms underlying the host regulation by parasitoid wasps. Future research area and applied perspectives are also discussed, noting that advances in biocontrol technologies in Chinese agriculture informs research at the global level.

关键词： parasitoid wasp predator biological control/biocontrol biological control/biocontrol agent cereal crop vegetable crop mass-rearing field release plant volatile parasitoid-host interaction

Reasonable selection of yield criteria for quantitative analysis of unsaturated soil slope stability

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Journal of Mountain Science 2016年第7期13卷 1304-1312页

作者： liu Zi-zhen YAN zhi-xin REN zhi-hua QIU Zhan-hong DUAN jian School of Civil Engineering and Architecture Taizhou UniversityTaizhou 318000China School of Civil Engineering and Mechanics Lanzhou UniversityLanzhou 730000China Yunnan Province Highway Science and Technology Research Institute Kunming 650051China

The yield criterion parameters of the soil material change with different values of the cohesion and the angle of friction because of sustained rainfall infiltration. Based on the Mohr-Coulomb(M-C) and Drucker-Prager(D-P) yield criteria, some reasonable yield criteria selections were discussed for quantitative analysis of unsaturated soil slope stability. Moreover, a critical point was found at the effective angle of friction equaling to 16.5° by transformation of parameters related to unsaturated soil under sustained rainfall. When the effective angle of friction more than 16.5° through parameter transformation of different yield criteria under natural condition, the calculation result of the safety factor was such that: f(DP1) > f(M-C) > f(equivalent M-C) > f(DP2) > f(DP3). While the effective angle of friction less than 16.5°, through parameter transformation, the safety factors were in the following order: f(DP1) > f(M-C) > f(DP2) > f(equivalent M-C) > f(DP3). The calculated results from a case study showed that the equivalent M-C yield criterion should be the best at evaluating soil slope stability before rainfall; the DP2 yield criterion should be selected to calculate the soil slope stability at the effective angle of friction less than 16.5° under sustained rainfall. The yield criterion should be selected or adjusted reasonably to calculate the safety factor of unsaturated soil slopes before and during sustained rainfall.

关键词： Unsaturated soil slope Yield criteria Parameter transformation Rainfall Safety factor

Microstructure of a Ti–50wt% Ta alloy produced via laser powder bed fusion

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Acta Metallurgica Sinica(English Letters) 2020年第7期33卷 981-990页

作者： Lei-Lei Xing Cong-Cong Zhao Hao Chen zhi-jian Shen Wei liu School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China Jihua Laboratory 13th FloorChengye buildingNanping West Road No.13GuichengNanhai districtFoshan cityGuangdong province 528000China Arrhenius Laboratory Department of Materials and Environmental ChemistryStockholm University10691StockholmSweden

Ti-Ta alloys have been widely studied for biomedical applications due to their high biocompatibility and corrosion *** this work,nearly fully dense and in situ alloyed Ti-50 wt% Ta samples were fabricated by the laser powder bed fusion(LPBF) of mechanically mixed *** increased exposure time,and thereby increased laser energy density,insoluble Ta particles were almost dissolved,and a Ti-50 wt% Ta alloy was *** and dendritic structures were formed due to constitutional undercooling,which was caused by the high cooling rate of LPBF *** retained βphases and α " phases were observed in the LPBFed Ti-50 wt% Ta *** α" phase was found at the boundary of the cellular structures,where the tantalum content was not high enough to suppress the bcc lattice transition completely but could suppress the β phase→α’ phase transition.

关键词： alloy Microstructure corrosion

Importance of incorporating systemic cerebroarterial hemodynamics into computational modeling of blood flow in intracranial aneurysm

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Journal of Hydrodynamics 2020年第3期32卷 510-522页

作者： zhi-qiang Zhang Li-jian Xu Rong liu Xiao-sheng liu Bing-Zhao Fu-you Liang School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration(CISSE) Shanghai 200240China Institute of Textiles and Clothing The Hong Kong Polytechnic UniversityHong KongChina Department of Radiology Ren Ji HospitalShanghai Jiao Tong University School of MedicineShanghai 200127China Department of Neurosurgery Ren Ji HospitalShanghai Jiao Tong University School of MedicineShanghai 200127China Institute for Personalized Medicine Sechenov UniversityMoscow 119991Russia

The importance of properly treating boundary conditions (BCs) in numerical simulation of hemodynamics in intracranial aneurysm (IA) has been increasingly recognized. In this study, we constructed three types of computational model for each IA to investigate how the outcome of numerical simulation is affected by the treatment of BCs. The first type of model (i.e., Type-A model) was obtained by applying 3-D hemodynamic modeling to the entire cerebral arterial network, with its solution being taken as the reference for evaluating the performance of the other two types of model (i.e., Type-B and Type-C models) in which 3-D modeling was confined to the aneurysm region. In addition, patient-specific 1-D models of the cerebral arterial network were developed to provide hemodynamic information for setting the inflow/outflow BCs of the 3-D models. Numerical tests on three IAs revealed that prescribing the outflow BCs of a localized 3-D aneurysm model based on 1-D model-simulated outflow division (i.e., Type-B model) instead of imposing the free outflow BC on all outlets (i.e., Type-C model) helped to improve the fidelity of the simulation of intra-aneurysmal hemodynamics, but could not guarantee a complete reproduction of the reference solution obtained by the Type-A model. Moreover, it was found that the outcome of hemodynamic simulation was more sensitive to the treatment of BCs when an aneurysm was located at arterial bifurcation rather than sidewall. These findings highlight the importance of taking into account systemic cerebroarterial hemodynamics in computational modeling of hemodynamics in IAs, especially those located at bifurcations.

关键词： Intracranial aneurysm systemic cerebroarterial hemodynamics boundary conditions computational model

Softening–melting behavior of mixed burden based on low-magnesium sinter and fluxed pellets

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International Journal of Minerals,Metallurgy and Materials 2021年第4期28卷 621-628页

作者： Gui-lin Wang jian Kang jian-liang Zhang Yao-zu Wang zhi-yu Wang Zheng-jian liu Chen-yang Xu School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China School of Chemical Engineering The University of QueenslandSt LuciaQLD 4072Australia Institute of Artificial Intelligence University of Science and Technology BeijingBeijing 100083China Baosteel Zhanjiang Iron and Steel Co. Ltd.Zhanjiang 524072China

A low MgO content in sinter is conducive to reduce the MgO content in blast furnace *** study investigated the effect of MgO content in sinter on the softening–melting behavior of the mixed burden based on fluxed *** the MgO content increased from 1.31 wt% to 1.55 wt%, the melting temperature of sinter increased to 1521℃.Such an increase was due to the formation of the high-meltingpoint slag *** reduction degradation index of sinter with 1.31 wt% MgO content was better than that of *** initial softening temperature of the mixed burden increased from 1104 to 1126℃ as MgO content in sinter increased from 1.31 wt% to 1.55 wt%, and the melting temperature decreased from 1494 to 1460℃.The permeability index(S-value) of mixed burden decreased to 594.46 kPa·℃ under a high MgO content with 1.55 wt%, indicating that the permeability was *** slag phase composition of burden was mainly akermarite(Ca_(2)MgSiO_(7)) when the MgO content in sinter was 1.55 wt%.The melting point of akermarite is 1450℃, which is lower than other phases.

关键词： magnesia softening–melting behavior low-magnesium sinter fluxed pellets slag

Relationship between martensite microstructure and ductility of H13 steel from aspect of crystallography

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Journal of Iron and Steel Research International 2021年第10期28卷 1268-1281页

作者： jian Zhu zhi-hao Zhang jian-xin Xie Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing100083China Key Laboratory for Advanced Materials Processing(MOE) University of Science and Technology BeijingBeijing100083China

Based on the parent austenite orientation reconstruction method,it is aimed to reveal the origination of high angle grain boundaries(HAGBs)and its relationship with ductility of H13 *** orientation relationship between martensite and parent austenite of quenched H13 samples was(123.5°,9.3°,192.5°),which agreed with the Kurdumov–Sachs *** variant distribution of quenched samples was dominated by close-packed plane group,and its high length fraction of V1/V2 inter-variant boundaries of calculated 62.6%was mainly contributed to HAGBs(>45°).When the quenched H13 samples underwent the pre-tempering treatment,their density of HAGBs(>45°)notably increased from 1.33 to 2.39μm^(−1),which improved its total elongation from 8.3%to 11.5%.Compared with the quenched H13 samples,the length fraction of V1/V2 inter-variant boundaries of H13 samples with pre-tempering for 5,10 and 60 min was reduced by 6.7%,7.0%and 7.5%,*** pre-tempering treatment,V1/V3&V5 variant pairs,etc.,merged V1/V2 variant pair by strain-induced grain boundary migration,which decreased the length fraction of V1/V2 inter-variant boundaries by 7.0%.The pre-tempering treatment significantly increased HAGBs(>45°)of H13 samples by sub-grains coarsening and strain-induced grain boundary migration mechanism.

关键词： H13 steel Pre-tempering treatment Variant selection Parent austenite orientation reconstruction High angle grain boundary

Cellular model of neuronal atrophy induced by DYNC111 deficiency reveals protective roles of RAS-RAF-MEK signaling

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Protein & Cell 2016年第9期7卷 638-650页

作者： zhi-Dong liu Su Zhang jian-Jin Hao Tao-Rong Xie jian-Sheng Kang Key Laboratory of Nutrition and Metabolism Institute for Nutritional Sciences Shanghai Institutes for Biological Sciences Chinese Academy of Sciences Shanghai 200231 China University of Chinese Academy of Sciences Beijing 100049 China

Neuronal atrophy is a common pathological feature occurred in aging and neurodegenerative diseases. A variety of abnormalities including motor protein mal- function and mitochondrial dysfunction contribute to the loss of neuronal architecture; however, less is known about the intracallular signaling pathways that can pro- tect against or delay this pathogenic process. Here, we show that the DYNClll deficiency, a neuron-specific dynein intermediate chain, causes neuronal atrophy in primary hippocampal neurons. With this cellular model, we are able to find that activation of *** signaling protects against neuronal atrophy induced by DYNClll deficiency, which relies on MEK-dependent autophagy in neuron. Moreover, we further reveal that BRAF also protects against neuronal atrophy induced by mitochondrial impairment. These findings demon- strate protective roles of the RAS-RAF-MEK axis against neuronal atrophy, and imply a new therapeutic target for clinical intervention.

关键词： RAS-RAF-MEK pathway atrophy dyneinintermediate chain mitochondria hippocampal neuron,autophagy