SUNKEN HOLLOW CARBON SPHERES SUPPORTED Pt ELECTROCATALYST FOR EFFICIENT METHANOL OXIDATION AND OXYGEN REDUCTION REACTION

XINHONG ZHAO,PENG WANG,NAIFEI REN 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.7

Sunken hollow carbon spheres (SHCs) are prepared by using glucose as carbon source andpolystyrene spheres (PSs) as templates. Pt particles are then loaded on the SHCs as electro-catalyst and used for catalyzing both methanol oxidation and oxygen reduction reaction (ORR)in acidic media. Physical measurements show that the SHCs are formed due to sinking of hollowcarbon spheres. It can be imagined that the SHCs have the similar speci¯c surface area ashollow carbon spheres with reduced volume. Moreover, the SHCs have high surface area(786 : 3 m 2 ・ g-1 ) with hollow and sunken structure are bene¯cial for the uniform dispersion ofthe noble metal particles and e±ciently improve the mass transfer in catalytic reactions. Thecyclic voltammogram measurements show that the current densities on Pt/SHC electrocatalystare 2.1 times (1284 mA ・ mg-1Pt) that on commercial Pt/C for methanol oxidation and 1.5 times(163 : 7 mA ・ mg-1Pt) that on Pt/C for ORR at the same Pt loadings, being promising candidatefor fuel cell electrocatalyst.

Influence of ultrasonic impact treatment on microstructure and mechanical properties of nickel-based alloy overlayer on austenitic stainless steel pipe butt girth joint

Zhao Xilong,Ren Kangming,Lu Xinhong,He Feng,Jiang Yuekai 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.11

Ultrasonic impact treatment (UIT) is carried out on the Ni-based alloy stainless steel pipe gas tungsten arc welding (GTAW) girth weld, the differences of microstructure, microhardness and shear strength distribution of the joint before and after ultrasonic shock are studied by microhardness test and shear punch test. The results show that after UIT, the plastic deformation layer is formed on the outside surface of the Ni-based alloy overlayer, single-phase austenite and g type precipitates are formed in the overlayer, and a large number of columnar crystals are formed on the bottom side of the overlayer. The average microhardness of the overlayer increased from 221 H V to 254 H V by 14.9%, the shear strength increased from 696 MPa to 882 MPa with an increase of 26.7% and the transverse average residual stress decreased from 102.71 MPa (tensile stress) to 18.33 MPa (compressive stress), the longitudinal average residual stress decreased from 114.87 MPa (tensile stress) to 84.64 MPa (compressive stress). The fracture surface has been appeared obvious shear lip marks and a few dimples. The element migrates at the fusion boundary between the Ni-based alloy overlayer and the austenitic stainless steel joint, which is leaded to form a local martensite zone and appear hot cracks. The welded joint is cooled by FA solidification mode, which is forming a large number of late and skeleton ferrite phase with an average microhardness of 190 H V and no obvious change in shear strength. The base metal is all austenitic phase with an average microhardness of 206 H V and shear strength of 696 MPa

Investigation on microstructure and mechanical properties of ni-based alloy overlayer by ultrasonic impact treatment

Xilong Zhao,Kangming Ren,Xinhong Lu,Feng He,Yuekai Jiang 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.8

Ultrasonic impact treatment (UIT) was performed on the Ni-based alloy overlayer of austenitic stainless steel pipe girth weld. The difference of microstructure, microhardness and maximum shear strength distribution of the joint before and after UIT was studied by autobiographic test and shear punch test. The electrode potential data were tested by a threeelectrode electrochemical workstation and tafel curve was drawn. The results show that a grain refinement layer of about 30 um and a transition layer of about 60 um are formed in the overlayer of nickel-based alloy after UIT. Meanwhile, the transition layer has high corrosion sensitivity to oxalic acid solution, and the main precipitates in the overlayer are austenite and M23C6. In 3.5 % NaCl solution, the self-corrosion potential is -432 mV. The average microhardness of the overlayer of nickel-based alloy is 270 HV, which is 18.9 % higher than that of the sample without UIT. In the meantime, the maximum shear strength of nickel-based alloy is 955 MPa, which is 9.6 % higher than the sample without UIT. It is found that the ferrite is mainly lath and skeleton with no obvious change under UIT or not. Meanwhile, an average microhardness is 191 HV, and shear strength is 678 MPa. The microstructure of the welded joint is mainly consisted of austenite phase and ferrite phase, and FA solidification mode has been a major influence in the welding process. At the boundary between overlayer and circumferential welded joint of 304 austenitic stainless steel, reheat cracks in this area are occurred easily. Due to the migration of carbon, local martensite bands will be formed which will lead to large heterogeneity of microhardness.

Preventive effect of Lactobacillus plantarum HFY09 on HCl/ethanol-induced gastric injury in mice

Li Fang,Sun Hailan,Ran Guangjun,Liu Xinhong,Yi Ruokun,Tan Fang,Zhao Xin,Liu Huazhi 한국응용생명화학회 2020 Applied Biological Chemistry (Appl Biol Chem) Vol.63 No.5

The aim of this study was to investigate the effect of Lactobacillus plantarum HFY09 on gastric injury induced by HCl/ ethanol in Kunming mice. The results showed that HFY09-H inhibited any increases in gastric juice volume, maintained the normal pH value of gastric acid, and reduced the damage caused to the gastric mucosa and gastric wall, the inhibition rate on the injury area reaches 63.70%. Compared with the negative control group, HFY09 increased the levels of serum somatostatin (SS) and vasoactive intestinal peptide (VIP), and also decreased the levels of substance P (SP), endothelin-1 (ET-1), interleukin-6 (IL-6), interleukin-12 (IL-12), tumor necrosis factor-α (TNF-α), and interferon-γ (IFN-γ). In addition, real time fluorescent quantitative PCR (Q-PCR) also confirmed that high-dose HFY09 ( 109 CFU/kg/ day) upregulated the mRNA expression of copper/zinc superoxide dismutase (Cu/Zn-SOD), manganese superoxide dismutase (Mn-SOD), catalase (CAT), endothelial nitric oxide synthase (eNOS), and neuronal nitric oxide synthase (nNOS), and downregulated the expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2). At the same time, the results of the HFY09 treatment group were similar to those of the ranitidine treatment group. These results indicate that HFY09 can prevent gastric injury induced by HCl/ethanol in vivo. Therefore, HFY09 may play a potential role in the treatment of gastric diseases.

A Lectin Receptor Kinase Positively Regulates ABA Response During Seed Germination and Is Involved in Salt and Osmotic Stress Response

Keqin Deng,Qiming Wang,Jianxin Zeng,Xinhong Guo,Xiaoying Zhao,Dongying Tang,Xuanming Liu 한국식물학회 2009 Journal of Plant Biology Vol.52 No.6

Lectin receptor-like kinases (LecRK) are widespread in higher plants; however, little is known about their physiological roles. In this study, At1g70130 (designated LecRK-b2), an Arabidopsis LecRK gene, has been investigated. LecRK-b2 was predominantly expressed during seed germination, and its expression was ceased following germination. The expression of LecRK-b2 was induced by abscisic acid (ABA), salt, and osmotic stress. LecRK-b2 lossof- function mutation slightly reduced the ABA sensitivity during seed germination, and this reduced sensitivity was demonstrated not due to lower ABA accumulation level in the seeds. Dual-luciferase transient expression assay confirmed that the transcription factor ABSCISIC ACID INSENSITIVE3 (ABI3) could activate the luciferase under driving of LecRK-b2 promoter. LecRK-b2 transcription level was found to be down-regulated in abi3 during seed germination. Furthermore, LecRK-b2 loss-of-function mutation reduced the salt and osmotic sensitivity during early development stage of Arabidopsis. Taken together, these results suggest that LecRK-b2 functions as a positive regulator of the ABA response during the seed germination and is involved in salt and osmotic stress response in the early development stage.

A R2R3-type MYB transcription factor gene from soybean, GmMYB12, is involved in flavonoids accumulation and abiotic stress tolerance in transgenic Arabidopsis

Feibing Wang,Xuqin Ren,Fan Zhang,Mingyang Qi,Huiyun Zhao,Xinhong Chen,Yuxiu Ye,Jiayin Yang,Shuguang Li,Yi Zhang,Yuan Niu,Qing Zhou 한국식물생명공학회 2019 Plant biotechnology reports Vol.13 No.3

The R2R3-type MYB transcription factors have been shown to increase flavonoids accumulation by regulating the expression of key enzyme genes related to flavonoid biosynthesis pathway. However, the roles and underlying mechanisms of the soybean GmMYB12 gene in regulation of flavonoids accumulation and tolerance to abiotic stresses are rarely known. In the present study, the GmMYB12 gene was isolated and its function was characterized. Sequence and yeast one-hybrid analyses showed that GmMYB12 contained two MYB domains and belonged to R2R3-MYB protein with transactivation activity. Subcellular localization analysis in onion epidermal cells indicated that GmMYB12 was localized to the nucleus. Overexpression of GmMYB12 increased the production of downstream flavonoids and the expression of related genes in the flavonoid biosynthesis pathway. It also improved resistance to salt and drought stresses during seed germination, root development, and growing stage. Further component and enzymatic analyses showed significant increases of proline content, pyrroline-5-carboxylate synthase (P5CS), superoxide dismutase (SOD), and peroxidase (POD) activities, as well as significant reduction of H2O2 and malonaldehyde (MDA) content under salt and drought stresses in transgenic plants. Meanwhile, the expression level of AtP5CS, AtSOD and AtPOD genes was up-regulated against salt and drought stresses. Together, our finding indicated that changing the expression level of GmMYB12 in plants alters the accumulation of flavonoids and regulates plantlet tolerance to abiotic stress by regulating osmotic balance, protecting membrane integrity and maintaining ROS homeostasis. The GmMYB12 gene has the potential to be used to increase the content of valuable flavonoids and improve the tolerance to abiotic stresses in plants