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Radiation induced grain boundary segregation in ferritic/martensitic steels
Xia, L.D.,Ji, Y.Z.,Liu, W.B.,Chen, H.,Yang, Z.G.,Zhang, C.,Chen, L.Q. Korean Nuclear Society 2020 Nuclear Engineering and Technology Vol.52 No.1
The radiation induced segregation of Cr at grain boundaries (GBs) in Ferritic/Martensitic steels was modeled assuming vacancy and interstitialcy diffusion mechanisms. In particular, the dependence of segregation on temperature and grain boundary misorientation angle was analyzed. It is found that Cr enriches at grain boundaries at low temperatures primarily through the interstitialcy mechanism while depletes at high temperatures predominantly through the vacancy mechanism. There is a crossover from Cr enrichment to depletion at an intermediate temperature where the Cr:Fe vacancy and interstitialcy diffusion coefficient ratios intersect. The bell-shape Cr enrichment response is attributed to the decreasing void sinks inside the grains as temperature rises. It is also shown that low angle grain boundaries (LAGBs) and special Σ coincidence-site lattice (CSL) grain boundaries exhibit suppressed radiation induced segregation (RIS) response while high angle grain boundaries (HAGBs) have high RIS segregation. This different behavior is attributed to the variations in dislocation density at different grain boundaries.
Radiation damage in helium ion – irradiated reduced activation ferritic/martensitic steel
L.D. Xia,W.B. Liu,H.P. Liu,J.H. Zhang,H. Chen,Z.G. Yang,C. Zhang 한국원자력학회 2018 Nuclear Engineering and Technology Vol.50 No.1
Nanocrystalline reduced activation ferritic/martensitic (RAFM) steel samples were prepared using surfacemechanical attrition treatment (SMAT). Un-SMATed and SMATed reduced activation ferritic/martensitic samples were irradiated by helium ions at 200 C and 350 C with 2 dpa and 8 dpa, respectively,to investigate the effects of grain boundaries (GBs) and temperature on the formation of Hebubbles during irradiation. Experimental results show that He bubbles are preferentially trapped at GBsin all the irradiated samples. Bubble denuded zones are clearly observed near the GBs at 350 C, whereasthe bubble denuded zones are not obvious in the samples irradiated at 200 C. The average bubble sizeincreases and the bubble density decreases with an increasing irradiation temperature from 200 C to350 C. Both the average size and density of the bubbles increase with an increasing irradiation dose from2 dpa to 8 dpa. Bubbles with smaller size and lower density were observed in the SMATed samples butnot in the un-SMATed samples irradiated in the same conditions, which indicate t
Santra, Sampa,Tomaras, Georgia D.,Warrier, Ranjit,Nicely, Nathan I.,Liao, Hua-Xin,Pollara, Justin,Liu, Pinghuang,Alam, S. Munir,Zhang, Ruijun,Cocklin, Sarah L.,Shen, Xiaoying,Duffy, Ryan,Xia, Shi-Mao Public Library of Science 2015 PLoS pathogens Vol.11 No.8
<▼1><P>HIV-1 mucosal transmission begins with virus or virus-infected cells moving through mucus across mucosal epithelium to infect CD4<SUP>+</SUP> T cells. Although broadly neutralizing antibodies (bnAbs) are the type of HIV-1 antibodies that are most likely protective, they are not induced with current vaccine candidates. In contrast, antibodies that do not neutralize primary HIV-1 strains in the TZM-bl infection assay are readily induced by current vaccine candidates and have also been implicated as secondary correlates of decreased HIV-1 risk in the RV144 vaccine efficacy trial. Here, we have studied the capacity of anti-Env monoclonal antibodies (mAbs) against either the immunodominant region of gp41 (7B2 IgG1), the first constant region of gp120 (A32 IgG1), or the third variable loop (V3) of gp120 (CH22 IgG1) to modulate <I>in vivo</I> rectal mucosal transmission of a high-dose simian-human immunodeficiency virus (SHIV-BaL) in rhesus macaques. 7B2 IgG1 or A32 IgG1, each containing mutations to enhance Fc function, was administered passively to rhesus macaques but afforded no protection against productive clinical infection while the positive control antibody CH22 IgG1 prevented infection in 4 of 6 animals. Enumeration of transmitted/founder (T/F) viruses revealed that passive infusion of each of the three antibodies significantly reduced the number of T/F genomes. Thus, some antibodies that bind HIV-1 Env but fail to neutralize virus in traditional neutralization assays may limit the number of T/F viruses involved in transmission without leading to enhancement of viral infection. For one of these mAbs, gp41 mAb 7B2, we provide the first co-crystal structure in complex with a common cyclical loop motif demonstrated to be critical for infection by other retroviruses.</P></▼1><▼2><P><B>Author Summary</B></P><P>Antibodies specifically recognize antigenic sites on pathogens and can mediate multiple antiviral functions through engagement of effector cells via their Fc region. Current HIV-1 vaccine candidates induce polyclonal antibody responses with multiple antiviral functions, but do not induce broadly neutralizing antibodies. An improved understanding of whether certain types of non-neutralizing HIV-1 specific antibodies can individually protect against HIV-1 infection may facilitate vaccine development. Here, we test whether non-neutralizing antibodies with multiple antiviral functions mediated through FcR engagement and recognition of virus particles or virus-infected cells can limit infection, despite lacking classical virus neutralization activity. In a passive antibody infusion-rhesus macaque challenge model, we tested the ability of non-neutralizing monoclonal antibodies to limit virus acquisition. We demonstrate that two different types of non-neutralizing antibodies, one that recognizes both virus particles and infected cells (7B2) and another that recognizes only infected cells (A32) were capable of decreasing the number of transmitted founder viruses. Further, we provide the structure of 7B2 in complex with the gp41 cyclical loop motif, a motif critical for entry. These findings provide insights into the role that antibodies with antiviral properties, including virion capture and FcR mediated effector function, may play in protecting against HIV-1 acquisition.</P></▼2>
Yun, S.H.,Xia, L.,Edison, T.N.J.I.,Pandurangan, M.,Kim, D.H.,Kim, S.H.,Lee, Y.R. Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.240 No.-
A novel ethylenediamine (EDA) based chemosensor 5 [dimethyl 2,2'-((3-oxocyclohex-1-ene-1,2-diyl)bis(azanediyl))dibenzoate] has been designed and synthesized for the turn on fluorescence sensing of Cu<SUP>2+</SUP> ions. The molecular geometry configuration of 5 is identified by X-ray diffraction and its corresponding orbital electron distributions are predicted by density functional theory (DFT). The probe 5 exhibits strong and selective complexing ability towards Cu<SUP>2+</SUP> over the other metal ions tested in both acetonitrile and aqueous solvent systems. MeCN-HEPES buffer system is more suitable for the selective fluorescence sensing of Cu<SUP>2+</SUP> ions. In addition, the lowest detection limit is 0.30μM for Cu<SUP>2+</SUP> ions. This probe has also been applied successfully for the confocal fluorescence imaging of MDCK cells. Therefore, this probe can be used in both the environmental and biological systems for the detection of Cu<SUP>2+</SUP>.
Jaeger, S.R.,Kim, K.O.,Lee, S.M.,Hunter, D.C.,Kam, K.,Chheang, S.L.,Jin, D.,Lee, P.Y.,Xia, Y.,Ares, G. Longman Scientific Technical ; Elsevier Science Pu 2017 Food quality and preference Vol.56 No.1
<P>In line with research in non-Western countries becoming main-stream, the need to validate existing research methods with consumers from these populations increase. The present research contributes hereto by quasi-replicating with Korean and Chinese consumers previous research concerning the risk of hedonic product responses being biased by co-elicitation of CATA/RATA questions for sensory product characterisation. Using consumers in several Western countries it was previously reported that bias could occur, but was unlikely to. Eleven studies involving 1000 East Asian consumers confirmed this conclusion. The studies were conducted with diversified populations and across multiple product categories. Across 7 studies, there were no instances where CATA co-elicitation was found to bias hedonic scores. However, in one of four studies where RATA responses were co-elicited bias did occur, and hedonic scores were, on average, lower when RATA responses were co-elicited. It is recommended that the research be replicated with consumers residing in their home countries and extended to other East and South-East Asian counties. (C) 2016 Elsevier Ltd. All rights reserved.</P>