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3. Dislocation loop formation during proton irradiation of zirconium

Author

Xu, Xiao Dan, Frankel, Philipp, and Preuss, Michael

Subjects
irradiation growth, zirconium, dislocation loop, X-ray diffraction, Transmission electron microscopy, proton irradiation, nuclear materials
Abstract

Zirconium components in the nuclear reactor core undergo continuous neutron irradiation throughout its lifetime. Irradiation causes the displacement of atoms and the production of point defects, self-interstitial atoms and vacancies, which may further reconfigure into dislocation loops which are unique features of irradiation-damage. The evolution of dislocation loops in zirconium alloys are relevant to a macroscopic shape change known as irradiation-induced growth (IIG), characterized by a lengthening along prismatic crystallographic directions and a corresponding shrinkage along the basal pole direction. In neutron irradiated zirconium, prismatic a-loops of both vacancy and interstitial nature appear starting from a low radiation dose, and vacancy-type basal c-loops are later observed at higher doses correlating with an accelerated breakaway growth phenomenon. This work is part of a global collective effort to understand dislocation loop evolution and irradiation growth. We used proton-irradiation as a surrogate for neutron-irradiation to generate a variety of irradiation-damage microstructures, corresponding to a series of irradiation conditions, in both a commercial alloy, Zircaloy-4, and a nominally pure zirconium. We used state-of-the-art characterization techniques such as bright field scanning transmission electron microscopy (BF STEM) in tandem with X-ray diffraction (XRD) line profile analysis in an attempt to fully characterize dislocation loops in terms of their nature, size, distribution, and density. Pure zirconium specimens proton-irradiated to 4dpa at 350C had conveniently larger a-loops than usually found in their commercial alloy counterparts, allowing us to successfully use TEM techniques to characterize the nature of the loops. In this specimen, we observed the alignment of a-loops both parallel to the basal plane traces and parallel to the 10-10 directions. Loops in alignment with one another were of identical Burgers vectors, either all vacancy or all interstitial in nature. In an effort to validate and optimize the use of XRD line profile analysis for the study of irradiation microstructure, we measured the diffraction profile of Zircaloy-4 and pure Zr with a range of proton-irradiated damage microstructures using three slightly different experimental geometries, one of which was in the laboratory setting, and two were using synchrotron X-ray diffractometers. We found that diffraction line profile analysis produced dislocation density results that were reproducible within experimental error when comparing data from different diffraction geometries. Satellite peaks associated with irradiation-induced dislocation loops, however, varied in relative volume fraction from experiment to experiment, suggesting a significant grain-to-grain variation in the average nature of dislocation loops. Furthermore, using high energy synchrotron transmission X-ray diffraction, we performed a novel depth profiling experiment on proton-irradiated Zircaloy-4 and an alloy of Zr-0.1%Fe. We measured the ways in which dislocation loop density and strain broadening varied with respect to depth below the irradiation surface, and we found a saturation of irradiation-induced strain broadening occurring from a low dose 0.7dpa, above which a-loop nucleation was hindered and a-loops grew in size to maintain a steady-state strain. We discuss our results with respect to known phases of IIG to form an updated hypothesis of the mechanisms by which irradiation-damage evolves within zirconium alloys.

Published
2020

14. Dirigent gene family identification and expression profiling of Vigna angularis responsive to Uromyces vignae infection.

Author

KE Xi-Wang, YUAN Meng-Qi, XU Xiao-Dan, YIN Li-Hua, GUO Yong-Xia, and ZUO Yu-Hu

Abstract

To clarify the role of Dirigent (DIR) gene family of adzuki bean (Vigna angularis) in response to Uromyces vignae infection, genome-wide identification of the DIR family genes of V. angularis (VaDIRs) was conducted. A total of 33 VaDIRs in the V. angularis genome were identified, among which 29 members were located on 8 chromosomes, respectively. Phylogenetic analysis showed that VaDIRs consisted of 4 subfamilies (DIR-a, DIR-b/d, DIR-e, and DIR-f). Cis-acting elements analysis of the promoter of VaDIRs indicated that all members of VaDIRs contained hormones and pathogen responsive elements. Transcriptomic data of the rust resistant cultivar at different times after inoculation revealed that 17 VaDIRs members were differentially expressed, among which 6 VaDIRs were significantly upregulated at 24 hours post inoculation (hpi), and 2 members were highly expressed both at 24 and 48 hpi. The relative expression of the genes mentioned above were further confirmed in different resistant cultivars responsive to U. vignae infection by qRT-PCR. Results demonstrated that VaDIR14, VaDIR16, and VaDIR33 in resistant cultivar were significantly induced than those in the susceptible cultivar during the fungal infection. In short, our results indicated that members of VaDIRs could be used as positive regulators in resistant cultivar to prevent U. vignae infection. [ABSTRACT FROM AUTHOR]

Published
2022
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23. Retraction: Antidepressant-Like Activity of YL-0919: A Novel Combined Selective Serotonin Reuptake Inhibitor and 5-HT1A Receptor Agonist.

Author

Chen, Hong-xia, Jin, Zeng-liang, Zhang, Li-ming, Xue, Rui, Xu, Xiao-dan, Zhao, Nan, Qiu, Zhi-kun, Wang, Xian-wang, Zhang, You-zhi, Yang, Ri-fang, and Li, Yun-feng

Subjects
SEROTONIN uptake inhibitors
Abstract

The article titled "Retraction: Antidepressant-Like Activity of YL-0919: A Novel Combined Selective Serotonin Reuptake Inhibitor and 5-HT1A Receptor Agonist" has been retracted by the corresponding author due to lack of confidence in the results. The authors discovered methodological errors in Tables 3 and 4, which rendered the results unreliable. It was found that YL-0919 is not a selective SERT/5-HT1A receptor agonist as previously reported. The experimental conditions used in the study led to significant degradation of the collected membrane protein, and the buffer used affected the binding results. The authors and the publisher apologize for the oversight. [Extracted from the article]

Published
2024
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26. Endoscopic treatment for choledocholithiasis in asymptomatic patients.

Author

Xu, Xiao‐Dan, Qian, Jian‐Qing, Dai, Jian‐Jun, and Sun, Zhen‐Xing

Subjects
*ENDOSCOPIC retrograde cholangiopancreatography, *BILE ducts, *REGRESSION analysis, *MULTIVARIATE analysis, *ODDS ratio
Abstract

Background and Aim: A few small retrospective studies recently found that endoscopic retrograde cholangiopancreatography (ERCP) in asymptomatic compared with symptomatic common bile duct stones (CBDSs) patients appeared to increase the risk of post‐ERCP pancreatitis (PEP). This study aimed to determine the risk of ERCP in asymptomatic CBDS patients. Methods: A total of 327 consecutive patients with native papilla were invited to participate into the study and divided into two groups: 53 in the asymptomatic group and 274 in the symptomatic group, who underwent CBDS removal by ERCP. Patient's characteristics and outcomes were analyzed. Results: A total of 46 (14.1%) patients had ERCP‐related complications, including PEP, cholangitis, perforation, and bleeding. The overall complication rate in the asymptomatic group was higher than in the control group (26.4% vs 11.7%, P < 0.01). PEP was the most common complication (30/327, 9.2%). Of the 30 cases of PEP, 25 (83.3%) were mild, and the severity in both groups was similar (9/1/1 vs 16/2/1, P > 0.05). The incidence rate of PEP in the asymptomatic group was higher than in the symptomatic group (20.8% vs 6.9%, P < 0.01). Multivariate regression analysis identified asymptomatic CBDSs (odds ratio = 0.241, 95% confidence interval: 0.092–0.628) as being independently associated with PEP occurrence. Conclusion: Asymptomatic CBDSs were associated with increased incidence of PEP compared with symptomatic CBDSs. [ABSTRACT FROM AUTHOR]

Published
2020
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