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Yongjin Wang,Yingchao Zhang,Renbo Song,Liang Huang,Yu Pei 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10
The effect of austenitizing temperature on microstructure evolution and impact toughness of a newly developed Fe–3.0C–2.8Si–2.0Mn–0.9V–0.2Cr bainite ductile iron was investigated in this research. The ductile iron specimens were heat treatedunder different continuous cooling process, involving austenitizing between 900 and 980 °C and followed tempering at200 °C. Optical microscopy, X-ray diffraction, scanning electron microscope and transmission electron microscope tests wereconducted to investigate the microstructure evolution. Impact toughness and Rockwell hardness were measured. The resultsshowed that the microstructure of the ductile iron mainly consisted of graphite, acicular bainite and retained austenite aftercontinuous cooling process. The austenitizing temperature could change the volume fraction and size of bainite and retainedaustenite. There existed a C-area, where retained austenite accumulated near the graphite, except for specimen austenitizedat 920 °C. The impact toughness of specimens increased first and then get worse with the increasing of austenitizing temperature. The impact toughness was related with the volume fraction of bainite and the morphology of retained austenite. The fracture mechanism of the bainite ductile iron belonged to cleavage fracture. Chunky graphite acted as the source ofmicrocrack during the impact process. The bulky retained austenite behaved as a prior path for the microcrack propagation,while the bainite and thin filmy retained austenite limited its propagation.
The New Bubble–Slurry for Sand Conditioning during EPB Shield Tunnelling: A Laboratory Scale Study
Lu Wang,Wei Zhu,Yongjin Qian,Huitang Xing 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5
Spewing is a key issue during earth pressure balance (EPB) shield tunneling in a water-rich sandy stratum. This paper proposed the bubble–slurry as a new type of soil conditioning agent. The foamability and stability of the bubble–slurry were studied, and the volume stability, fluidity, and permeability of bubble–slurry-conditioned sands with hydraulic gradient of 2 to 10 were analyzed. The stability mechanism was explored by the zeta potential and microstructure of the bubble–slurry system. The formulation of bubble–slurry with a half-life of 121 – 383 h was determined through laboratory tests. The results of soil conditioning experiments showed that the bubble–slurry-conditioned soil exhibited appropriate fluidity, excellent volume stability and low permeability in a certain period. The use of bubble–slurry can save approximately 3.0–8.2% of the slurry consumption compared with the method of slurry conditioning. The zeta potential and the distribution of slurry particles of the bubble–slurry system were key mechanisms affecting the stability of the bubble–slurry. The high absolute value of zeta potential of the system increases the dispersion of bubbles, and the slurry particles uniformly distributed on the bubble liquid film and in the Plateau boundary are conducive to enhancing the anti-disturbance ability and inhibiting the decay of bubbles.
Zhang Liuyan,Wang Xiujin,Wu Huishu,Mai Yongjin,Liu Cansen,Jie Xiaohua 한국탄소학회 2020 Carbon Letters Vol.30 No.5
In this paper, graphene-coated Al powders prepared by in situ reduction method were directly used for cold spraying, obtain�ing a graphene-reinforced Al matrix composite coating with more compact structure and better performance. Cross-sectional analysis revealed that compared with the pure Al powders, the graphene-coated Al powders were more severely deformed, and the resulting coating was denser and its porosity was reduced by over 80%. The hardness of the graphene-coated Al coating was increased by 40%, and its brine immersion time was prolonged by nearly three times. However, the graphene increases the pitting sensitivity of the Al coating; so, the enhanced corrosion resistance of the graphene-coated Al coating is mainly attributed to the improvement of its structure densifcation.
Xiang, Dong,Jeong, Hyunhak,Kim, Dongku,Lee, Takhee,Cheng, Yongjin,Wang, Qingling,Mayer, Dirk American Chemical Society 2013 Nano letters Vol.13 No.6
<P>Molecules are promising candidates for electronic device components because of their small size, chemical tunability, and ability to self-assemble. A major challenge when building molecule-based electronic devices is forming reliable molecular junctions and controlling the electrical current through the junctions. Here, we report a three-terminal junction that combines both the ability to form a stable single-molecule junction via the mechanically controllable break junction (MCBJ) technique and the ability to shift the energy levels of the molecule by gating. Using a noncontact side-gate electrode located a few nanometers away from the molecular junction, the conductance of the molecule could be dramatically modulated because the electrical field applied to the molecular junction from the side gate changed the molecular electronic structure, as confirmed by the ab initio calculations. Our study will provide a new design for mechanically stable single-molecule transistor junctions fabricated by the MCBJ method.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/nalefd/2013/nalefd.2013.13.issue-6/nl401067x/production/images/medium/nl-2013-01067x_0006.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nl401067x'>ACS Electronic Supporting Info</A></P>
Rui Yang,Yuqian Liu,Jingjing Xu,Wenting Shang,Xiaoyuan Zhang,Yongjin Wang,Chris Blanchard,Zhongkai Zhou 한국식품과학회 2018 Food Science and Biotechnology Vol.27 No.6
Epigallocatechin gallate (EGCG) is sensitive to heat thus its application in food industry is limited. In this work, rice bran albumin protein (RAP) was used as a carrier for EGCG. RAP-EGCG complexes (RAPE) were prepared with the binding number n of 0.0505:1 (EGCG: RAP, w/w) and binding constant K of (0.74 ± 0.002) 9 104 M-1, which suggests that hydrogen bond/van der Waals forces played important roles in such binding. FTIR analysis demonstrated that EGCG could induce the secondary structure changes of RAP above the ratio of 1.92:1 (EGCG:RAP, w/w). Dynamic light scattering and scanning electron microscope results showed that EGCG could trigger RAP association. Furthermore, the EGCG stability in RAPE was significantly improved than that of free EGCG in 10–60 C. The antioxidant ability of EGCG in RAPE was partially retained. These findings prove that RAP is a potential carrier for polyphenols and is beneficial for mechanism investigation between protein and polyphenols.
Lee, Eunjung,Jung, Dae Young,Kim, Jong Hun,Patel, Payal R.,Hu, Xiaodi,Lee, Yongjin,Azuma, Yoshihiro,Wang, Hsun-Fan,Tsitsilianos, Nicholas,Shafiq, Umber,Kwon, Jung Yeon,Lee, Hyong Joo,Lee, Ki Won,Kim, The Federation of American Societies for Experimen 2015 The FASEB Journal Vol.29 No.8
<P>Insulin resistance is a major characteristic of obesity and type 2 diabetes, but the underlying mechanism is unclear. Recent studies have shown a metabolic role of capsaicin that may be mediated <I>via</I> the transient receptor potential vanilloid type-1 (TRPV1) channel. In this study, TRPV1 knockout (KO) and wild-type (WT) mice (as controls) were fed a high-fat diet (HFD), and metabolic studies were performed to measure insulin and leptin action. The TRPV1 KO mice became more obese than the WT mice after HFD, partly attributed to altered energy balance and leptin resistance in the KO mice. The hyperinsulinemic-euglycemic clamp experiment showed that the TRPV1 KO mice were more insulin resistant after HFD because of the ∼40% reduction in glucose metabolism in the white and brown adipose tissue, compared with that in the WT mice. Leptin treatment failed to suppress food intake, and leptin-mediated hypothalamic signal transducer and activator of transcription (STAT)-3 activity was blunted in the TRPV1 KO mice. We also found that the TRPV1 KO mice were more obese and insulin resistant than the WT mice at 9 mo of age. Taken together, these results indicate that lacking TRPV1 exacerbates the obesity and insulin resistance associated with an HFD and aging, and our findings further suggest that TRPV1 has a major role in regulating glucose metabolism and hypothalamic leptin’s effects in obesity.—Lee, E., Jung, D. Y., Kim, J. H., Patel, P. R., Hu, X., Lee, Y., Azuma, Y., Wang, H.-F., Tsitsilianos, N., Shafiq, U., Kwon, J. Y., Lee, H. J., Lee, K. W., Kim, J. K. Transient receptor potential vanilloid type-1 channel regulates diet-induced obesity, insulin resistance, and leptin resistance.</P>