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Objective·To investigate the imaging features of computed tomography (CT) and magnetic resonance imaging (MRI) in the patients with Kimura disease (KD) in the head and neck.Methods·Sixty-four cases of KD in the head and neck comfirmed by histopathology were retrospectively collected from 2009 to 2023 in Shanghai Ninth People′s Hospital, Shanghai Jiao Tong University School of Medicine. All patients completed CT and/or MRI enhancement imaging before surgery. Clinical and imaging characteristics were collected, recorded and analyzed, including age, gender, peripheral blood eosinophilic ratio, serum IgE level, the lesion location, shape, size, CT density and degree of enhancement, MRI signal intensity and degree of enhancement, apparent diffusion coefficient (ADC), time-signal intensity curve (TIC) patterns, wash-in rate, and time to peak (TTP).Results·The average age of the 64 KD patients was (40±19) years, and 92.2% were males. A total of 73.5% of the patients showed an elevated ratio of peripheral blood eosinophil, and all 10 tested patients exhibited increased serum IgE levels. There were 82 extranodal (subcutaneous and glandular) lesions and 144 lymph node lesions detected by CT and MRI. Among the extranodal lesions, 80.5% were subcutaneous or glandular patchy lesions with unclear boundaries, and the rest were nodular lesions with clear boundaries. All lesions exhibited isodensity on CT scans and showed isointensity on T1-weighted imaging (T1WI) and hyperintensity on T2-weighted imaging (T2WI) in MRI. Most extranodal lesions tended to show heterogeneous enhancement, while most lymph node lesions showed homogeneous enhancement. The median ADCs of the extranodal lesions and the lymph node lesions were 1.04×10-3 mm2/s and 0.67×10-3 mm2/s, respectively, which were significantly different (P=0.000). The dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) results showed that the TIC patterns of extranodal lesions were predominantly type Ⅰ and Ⅱ, accounting for 57.5% and 42.5%, respectively; while the TIC patterns of lymph node lesions were predominantly type Ⅱ (96.6%). The difference in the TTP and the wash-in rate between the extranodal lesions and the lymph node lesions were both statistically significant (P=0.000).Conclusion·Extranodal lesions and lymph node lesions of KD both show isodensity on CT, and isointensity on T1WI and hyperintensity on T2WI in MRI. Extranodal lesions often show high ADC, TIC type Ⅰ or Ⅱ, and mostly heterogeneous enhancement; lymph node lesions often show low ADC, TIC type Ⅱ, and mostly homogenous enhancement.

The nuclear reactor system is complex and the operating environment is harsh, resulting in the complex phenomena of multi-physics coupling. The multi-physics coupling codes developed in the early stage shows limitations on codes' scalability and generality. Therefore, it is of great significance to build a multi-physics coupling framework and conduct research on key technologies in coupling problems, which may accelerate the development process of autonomous multi-physics coupling platform in China. In this paper, the multi-dimensional and multi-physics coupling finite element analysis platform for nuclear reactor developed by XJTU-NuTHeL was introduced. The main work consisted of the development of thermal-hydraulic model, the research of fuel performance analysis technology and the establishment of multi-physics coupling framework. In terms of thermal-hydraulic calculation, XJTU-NuTHeL conducted a series of studies on pressurized water reactors and advanced reactors grounded in the advanced multi-physics coupling framework, and developed the nuclear reactor system safety analysis code, NUSAC. In addition, a subchannel analysis model tailored for liquid metal fast reactors was established, and the fully coupled subchannel transient analysis code, FLARE, was developed. NUSAC and FLARE were then verified against relevant codes and experimental data. In the realm of fuel performance analysis, considering the wide application of finite element method in solid mechanics and its versatile modeling capabilities, XJTU-NuTHeL developed a fuel performance analysis code, BEEs, based on finite element method. The code could not only conduct multi-physics coupling analysis for traditional rod fuels under steady and transient conditions, but also extends its applicability to accident tolerant fuels and other fuels with diverse geometric shapes. This paper focused on the study and analysis of coated particle dispersed fuel and plate type fuel. The multi-scale simulation results of coated particle dispersed fuels, as well as the thermomechanical and corrosion behavior of plate type fuels were shown. In the context of multi-physics coupling analysis, the efficiency and accuracy of different mesh grid mapping schemes were studied and a multi-physics coupling framework was established. An example of the framework was then presented, showcasing the integration of the fuel performance code BEEs, the Monte Carlo neutron physics code OpenMC, and reactor system safety analysis code NUSAC. The keys parameters of mechanics, thermal-hydraulic and neutronics were obtained and analyzed through the coupling different codes. The multi-dimensional and multi-physics coupling finite element analysis platform built in this paper can provide a strong support for the high-fidelity numerical simulation of nuclear reactor multi-scale and multi-physics coupling.

Objective·To investigate the effect of ceria nanoparticles-polyethylene glycol (CeNP-PEG) on scavenging reactive oxygen species (ROS) and alleviating disease activity in dextran sulphate sodium (DSS)-induced colitis mice.Methods·CeNP was synthesized with the hydrates of cerium acetate, oleamine, and xylene, which was modified with polyethylene glycol-stearyl phosphatidylethanolamine (mPEG-DPSE) to obtain CeNP-PEG. Then CeNP-PEG was purified. The particle size and zeta potential of CeNP-PEG were measured by using transmission electron microscopy (TEM) and dynamic light scattering (DLS). Mouse macrophages (Raw264.7) were cultured in vitro and induced to a pro-inflammatory phenotype (M1 phenotype). M1 macrophages were treated with 0.5 µg/mL and 1.0 µg/mL CeNP-PEG, respectively, and then Western blotting was used to detect the expression changes of the proteins related with nuclear factor-κB (NF-κB) signaling pathway. DSS-induced colitis mice models were constructed, and CeNP-PEG (1.0 mg/mL) was intravenously administrated for 3 times via tail vein during the modeling period. Meanwhile, the body weight, fecal characteristics, and frequency of rectal bleeding in mice were monitored in the normal control group (Normal group), the model group (DSS group), and the CeNP-PEG treatment group. The disease activity index (DAI) was calculated to evaluate the intestinal inflammation. The level of ROS in mouse intestinal tissues was detected by dihydroethidine (DHE) staining and the mRNA expression levels of inflammatory cytokines interferon-γ (Ifn-γ), interleukin-6 (Il-6), Il-1β and tumor necrosis factor-α (Tnf-α) were detected by real-time quantitative PCR (RT-qPCR).Results·The hydrated particle size of synthesized CeNP-PEG was (6.96±0.27) nm, and the average zeta potential was (-6.02±1.31) mV. Western blotting results showed that the expression of p-P65 increased in the pro-inflammatory macrophages compared with the control group. The expression of NF-κB inhibitor-α (IκB-α) decreased, and their expressions tended to recover after the intervention of different concentrations of CeNP-PEG. In the DSS-induced colitis models, mice in the CeNP-PEG treatment group lost less weight than those in the DSS group (P=0.000) and had lower DAI scores (P=0.000). The RT-qPCR results of intestinal tissues showed that the mRNA levels of Ifn-γ, Il-1β, Il-6 and Tnf-α in the DSS group were significantly up-regulated compared with those in the Normal group (P=0.000), and all of them significantly decreased in the CeNP-PEG treatment group. The results of DHE staining showed that the fluorescence intensity of intestinal tissues in the DSS group was significantly enhanced than that in the Normal group, and the fluorescence intensity decreased in the CeNP-PEG treatment group.Conclusion·CeNP-PEG can inhibit the expression of intestinal inflammatory factors and the activation of NF-κB-related inflammatory pathway of pro-inflammatory macrophages, eliminate intestinal ROS, improve the intestinal inflammatory microenvironment, and alleviate the disease activity of DSS-induced colitis in mice.

BackgroundHeat pipe cooled reactor (HPR) has many characteristics, such as reliability, inherent safety, small volume, modularity, and solid core. The nuclear fuel of solid core is seriously affected by high temperature, strong irradiation, and solid constraint when operating, which affect the heat transfer performance and mechanical properties of the core seriously. The stress and gap heat transfer caused by the contact between monolith and other components change nonlinearly with the increase of burnup, and they influence each other. Therefore, the coupled irradiation-thermal-mechanical behavior of the monolith is a complex multi-physics phenomena.PurposeThis study aims to develop a coupled irradiation-thermal-mechanical model to explore the characteristics of gap variation, heat transfer and mechanics during the lifetime of solid core.MethodsFirst of all, based on the geometric parameter and material of a typical solid core of HPR with fuel rod composed of UO2 pellets and 316 stainless steel cladding, a coupled irradiation-thermal-mechanical model was developed and applied to the finite element multi-physics field analysis software COMSOL. The calculation parameter settings mainly referred to the design parameters of the MegaPower reactor. Then, a thermal conductivity model changing with the increase of burnup for UO2, the gap heat transfer model and mechanical contact were introduced in the gaps in the solid core, and both irradiation-induced deformation effect including densification and fission product swelling, and creep effect of UO2 pellets and 316 stainless steel monolith were taken into account. Finally, the model was applied to calculating the typical HPR and the characteristics of gap variation, heat transfer and mechanics were analyzed.ResultsAnalysis results show that pellet temperature and creep of monolith and cladding increase after complete contact between monolith and cladding. A smaller average number of heat pipes around the fuel rod result in higher temperature and stress distribution in the nearby area, and the cladding in this area has a risk of creep failure during its lifetime caused by internal pressure of the fuel rod and contact pressure between the monolith and cladding.ConclusionsThe gap contact can affect the heat transfer and mechanical properties of the solid core of HPR, and even result in an increase in the risk of cladding failure.

BackgroundThe enrichment of nuclear fuel may significantly influence the fuel performance of a reactor.PurposeThis study aims to explore the effect of U3Si2-Al plate-type fuel enrichment on its performance,MethodsThe fuel performance analysis code BEEs-Plates, neutronics Monte Carlo code OpenMC, and the one-dimensional system analysis code ZEBRA were coupled together within the MOOSE (Multiphysics Object-Oriented Simulation Environment) framework. Then the coupling code was employed to conduct the multiphysics coupling calculation for JRR-3 (Japanese Research Reactor No.3) fuel assembly enriched at 15%, 20%, and 25%. The data exchange among the three codes were realized with the help of interpolation transfer method implemented in MOOSE. Additionally, neutron physical parameters and fuel performance parameters after 231 d of operation were analyzed when the average fuel consumption of the module was 125.71 GWd∙tU-1.ResultsThe calculation results indicate that the max power density of fuel assembly enriched at 25% is 18% higher than the assembly enriched at 15%. Due to the high thermal conductivity of aluminum, the temperature difference in the fuel assembly is almost negligible whilst there is a significant difference in the fast neutron fluence. The results of fuel temperature and fast neutron fluence show that the volumetric strain is more obviously affected by the fuel temperature. Specifically, the plastic strain of the assembly with 25% enrichment is approximately 40% higher than that of the assembly with 15% enrichment.ConclusionThe analysis results of this study suggest that the assembly with a higher enrichment is more prone to failure.

Blistering usually occurs in plate-type fuels because of the absence of the gap between the cladding and the fuel meat. It can narrow coolant channels and deteriorate the local heat transfer, resulting in the increase of cladding temperature and plastic deformation, which threatens the integrity of fuel elements. Much research work mainly focuses on the causes of blistering and its effect on fuel elements, while few measures to reduce blistering were proposed. In view of the effect that Cr coating can effectively reduce the ballooning of fuel rod cladding during loss of coolant accident (LOCA), a design to apply Cr coating to plate-type fuels to restrain their blistering was proposed. In order to study the effect of Cr coating on the blistering of plate-type fuel elements, the simulation of a blistering test was conducted based on the MOOSE framework. The material properties of Zr and Cr were added, and the thermal creep, as well as plastic behavior after irradiation hardening was considered according to the characteristics of blistering. In addition, the effect of temperature and thickness of Cr coating on blistering were also analyzed and some important results were obtained. The simulation of the blistering test indicates that the reduction of blistering for the plate-type fuel cladding by Cr coating is not as significant as that of ballooning for the fuel rod cladding. The reason for the difference and the difference between the two phenomena were analyzed. The results also show that due to its low yield stress, Cr coating is likely to enter the plastic stage when the cladding blisters, which cannot effectively prevent the occurrence of blistering. However, owing to the low creep rate of Cr even at a relatively high temperature, the height of blistering can be reduced, and the higher the temperature, the more obvious the reduction effect. Under the premise of keeping the overall thickness of the cladding and the coating unchanged, even if the presence of Cr coating will reduce the thickness of cladding and thus reduce its mechanical strength, it can still effectively reduce the blistering height at high temperatures, and the thicker the coating, the more obvious the reduction effect. Nevertheless, adding Cr coating to the cladding of the original thickness has the most significant effect. From the results above, the main conclusion can be drawn: The thin coating can hardly affect the overall mechanical properties of the cladding, but it can effectively inhibit the creep, thereby reducing the blistering height.