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Effect of nano-CeO<sub>2</sub> on cobalt-based alloy laser coatings
Li, Mingxi,Zhang, Shihong,Li, Huisheng,He, Yizhu,Yoon, Jae-Hong,Cho, Tong-Yul Elsevier 2008 Journal of materials processing technology Vol. No.
<P><B>Abstract</B></P><P>Cobalt-based alloy coatings with/without nano-CeO<SUB>2</SUB> addition prepared by a 5kW CO<SUB>2</SUB> laser on Q235 low carbon steel were introduced. The effects of nanoparticles on the macro-quality, microstructure, phase composition, and wear resistance of the coatings were investigated. The microstructure and phases composition of the coatings were analyzed using Olympus-Pme-3 type microscope, Philip Xl 30 type scanning electron microscope and XD-3A type X-ray diffractometer (XRD). The wear resistance was tested using MM-200 type sliding wear machine, and the wear mechanism was analyzed by JSM-35C type scanning electron microscope (SEM). The results showed that defect (such as crack, gas hole, etc.) -free coatings were obtained. There existed γ-Co and Cr<SUB>23</SUB>C<SUB>6</SUB> in cobalt-based alloy coatings. Another two phases of CeCo<SUB>2</SUB> and ϵ-Co were identified with nanoparticles addition. Fine microstructure and equiaxed dendrite were obtained by adding nano-CeO<SUB>2</SUB>. The relative wear resistance is improved with the increased amount of nano-CeO<SUB>2</SUB>, and the coatings with the best wear resistance when laser power was 2.0kW by adding 1.5wt.% CeO<SUB>2</SUB>. The mechanism was found from abrasive/adhesive wear to fretting wear. The wear resistance decreased with 2.0wt.% CeO<SUB>2</SUB> addition.</P>
Cloning and functional characterization of two GsSnRK1 gene promoters from wild soybean
Chen Jun,Li Qiang,Zhang Pengmin,Lu Haoran,Bian Ya,Jian Yi,Wang Yizhu,Ding Xiaodong,Xiao Jialei 한국식물생명공학회 2021 Plant biotechnology reports Vol.15 No.5
Sucrose non-fermenting-related protein kinase 1 (SnRK1) belongs to a plant serine/threonine protein kinase family, and is part of a large interactive network of signaling pathways in plants to regulate many aspects of growth and development, and its gene expressions are highly responsive to multiple external stimuli. To functionally characterize the role of different SnRK1 members in wild soybean and identify the expression patterns of novel SnRK1 promoters for transgenic research, in this study, we performed an in silico analysis of the SnRK1 gene family in wild soybean and found GsSnRK1.1 and GsSnRK1.2 are main SnRK1 isoforms in wild soybean. The promoter fragments of both GsSnRK1.1 and GsSnRK1.2 were isolated, and a series of 5′-deletion and the full-length versions of both GsSnRK1.1 and GsSnRK1.2 promoters were fused with GUS reporter gene to generate expression vectors. The GUS activities in different tissues of seedling and adult growth stages of transgenic Arabidopsis plants were determined, and the GUS activities in transgenic Arabidopsis plants under NaCl, NaHCO3, PEG, ABA, MeJA and SA were also analyzed. The results showed that GsSnRK1.1 and GsSnRK1.2 genes have different expression patterns and both promoters may contain enhancers and silencers. In addition, NaCl, NaHCO3, ABA, MeJA, and PEG treatments enhanced, whereas SA treatment decreased the GUS activity under the control of both GsSnRK1.1 and GsSnRK1.2 promoters, which may be due to the distributions of various cis-elements in both GsSnRK1.1 and GsSnRK1.2 promoter regions. These results will contribute to a better understanding of the underlying mechanisms of GsSnRK1 genes in response to various abiotic stresses, and as stress-inducible promoters, GsSnRK1.1 and GsSnRK1.2 promoters can be candidates for practical application in agriculture.
Oxidation Behavior of CoCrFeMnNi High-Entropy Alloy Fabricated by Selective Laser Melting
Xiquan Jia,Zhenlin Xu,Yizhu He,Shengxuan Zhou,Xiaojie Du,Hui Zhang,Aiqin Mao 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.10
The present study investigated the microstructure and oxidation behavior of the CoCrFeMnNi high-entropy alloy (HEA) prepared by selective laser melting (SLM). The microstructure of the as-built sample comprised layer-by-layer overlapping melt pools, columnar grains, and cellular structures. The melt pool boundaries (MPBs) and cellular structures disappeared, and the dislocation density decreased after annealing at 900 °C. The high-temperature oxidation behavior of the CoCrFeMnNi HEA was investigated via oxidation kinetics, morphology observation, and oxidation product analysis. The oxidation kinetics followed the parabolic law at 800 to 1000 ℃. There were three layers of oxide scale at all temperatures. At 800 to 1000 °C, the inner oxide layer was Cr2O3; the intermediate layer consisted of Cr-oxides and Mn-oxides. The outer oxide layer mainly consisted of Mn2O3 at 800 to 900 °C and Mn3O4 at 1000 °C. At 1000 °C, the fast diffusion channels provided by MPBs led to preferential oxidation in the as-built HEA. And the preferential oxidation behavior in the annealed HEA was inhibited due to the removal of MPBs by annealing. At each temperature, the annealed HEA showed relatively better oxidation resistance than the as-built sample.
BiOCl/SnS2 Core-Shell Photocatalyst for the Degradation of Organic Pollutants
Hui Meng,Tingting Wang,Hongbin Chen,Yizhu Liu,Xiang Yu,Yi Zhu,Yuanming Zhang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.8
BiOCl/SnS2 core-shell heterojunction is prepared by a facile and economic hydrothermal method. The obtained BiOCl/SnS2 heterojunction displays high photocatalytic activity in the degradation of Rhodamine B (RhB). The high performance is explained by the fast separation of the photoinduced electron–hole pairs promoted by the heterojunction. The cycle life of the heterojunction is also improved compared with individual BiOCl or SnS2.
Dongbao Huang,Zhenlin Xu,Xiquan Jia,Haitao Yu,Yizhu He,Zhenqi Dong,Shenshen Li,Hui Zhang 대한금속·재료학회 2024 METALS AND MATERIALS International Vol.30 No.1
To solve the corrosion problem of the copper plates caused by fluoride ions, the Ni55 and CoCrNi medium-entropy alloycoatings were prepared via high-velocity oxygen fuel technology. The corrosion resistance of the Ni55 and CoCrNi coatingsin NaF solution was compared through electrochemical experiments and immersion corrosion experiments. The Ni55coating contained complex precipitated phases, resulting in preferential corrosion at the phase boundaries between the γ-Nisolid solution and the precipitated phases. The composition of the CoCrNi coating was more homogeneously distributed,and mainly uniform corrosion occurred. The corrosion products of the two coatings in the NaF solution were both complexescomposed of metal oxides and fluorides. Compared with the Ni55 coating, the passive film formed on the CoCrNi coatinghad a more uniform and protective property; therefore, the CoCrNi coating had better corrosion resistance. This researchcan pave a pathway for developing coating on copper and its alloys with excellent corrosion resistance.