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BackgroundDetectors based on the third-generation semiconductor material silicon carbide (SiC) offer several important advantages, such as compactness, faster charge-collection times, and easier n/γ identification, and they are widely used in reactor core dose monitoring.PurposeIn this study, the n/γ signal amplitude, neutron fluence rate, and linear response calibration performances were tested systematically for a self-developed third-generation SiC semiconductor detector.MethodsFirstly, the neutron conversion layer material 6LiF (with a 95% abundance of 6Li) was sprayed onto a SiC substrate using electron beam evaporation vacuum coating technology to achieve the optimized thickness of 25 μm for the self-developed third-generation SiC semiconductor detector. Then, 241Am α radioactive source (activity 9.37×103 Bq) was used to observe α particle response signal amplitude, and γ response testing of radiation was conducted in the 137Cs γ source (activity 6.23×107 Bq) environment. In addition, the SiC detector's neutron flux response linearity, γ dose rate response linearity and calibration of neutron fluence rate response linearity were measured in the standard radiation field systems.ResultsThe measurement results show that the SiC semiconductor detector has a linear fit of R² = 0.996 9 in the neutron fluence rate range of 1×103~1×106 cm-2∙s-1, with a good linear response, and the response range of the neutron/gamma dose is 0.005~20 Gy∙h-1.ConclusionThe SiC detectors with such good n/γ performance can be used for real-time and accurate monitoring of neutron and gamma doses in nuclear power field reactors.

The performance of tritium-based nuclear batteries based on two different energy conversion modes, the irradiated voltaic effect and irradiated photovoltaic effect, was studied by using the Monte Carlo method. The influence of the geometrical-physical parameters of energy conversion materials on the electrical output performance of batteries wais investigated. Single-layer and stacked-layer tritium-based nuclear batteries were designed and prepared. The effects of increasing the tritium source intensity and adopting the stacked-layer configuration on the enhancement of the electrical output of the batteries were analyzed. The simulation results showed that Si, SiC, and GaAs photovoltaic modules could be used for irradiated voltaic effect tritium-based nuclear batteries and that their respective optimal thickness parameters allow the electrical output performance to be optimized; the optimal thicknesses were 3.8 μm, 2.2 μm, and 1.7 μm, respectively. For irradiated photovoltaic effect tritium-based nuclear batteries, the thickness of the ZnS:Cu fluorescent layer could be adjusted to maximize the emitted fluorescence irradiance and optimized the electrical output performance. The experimental results showed that increasing the radiation intensity of the tritium source and adopting the stacked-layer configuration could effectively enhance electrical parameters such as the maximum output power of tritium-based nuclear batteries. The maximum output power of the stacked-layer nuclear battery could reach 106.138 nW, which was an increase of more than 64% compared with that of the single-layer configuration.

BackgroundNickel-, iron- and tungsten-based alloys are commonly used as structural materials of reactors. During their operational life, these alloys undergo intense neutron irradiation.PurposeThis study aims to analyze the post-irradiation defect evolution and its mechanisms in these materials for comprehending the effects of irradiation on them.MethodsThe displacement cascades in nickel, iron, and tungsten were examined at various temperatures (300⁓500 K), primary knock-on atom (PKA) energies (, and ) by using molecular dynamics (MD) simulations. Firstly, the model was initially relaxed at each specified temperature under a canonical ensemble for 10 ps, applying periodic boundary conditions in every direction. Then, an atom was randomly chosen as a PKA and assigned kinetic energy to initiate the cascade collision simulation in the micro-canonical ensemble. Finally, the Open Visualization Tool package was employed for visualization and data analysis of the irradiation cascade processes.ResultsThe simulation results reveal that nickel and iron exhibit similar steady-state defects. At lower PKA energies (

African swine fever (ASF) is a devastating disease, which is causing huge economic losses in China. Therefore, it is urgent to provide a rapid, highly specific and sensitive diagnostic method for the detection of African swine fever virus (ASFV), the ASF infectious agent. In this study, a novel quantitative real‐time polymerase chain reaction (qPCR) assay with lyophilized powder reagents (LPR), targeting the major structural protein p72 gene, was established for the detection of ASFV. This assay had many advantages, such as saving time and money, good sensitivity and repeatability. The sensitivity of this assay was 100 copies/μl of ASFV plasmid templates, and the assay showed 10‐fold greater sensitivity than a qPCR assay recommended by OIE. Furthermore, specificity analysis showed that qPCR with LPR for ASFV had no cross‐reactivity with other important swine pathogens. In clinical diagnoses of 218 blood samples of domestic pigs in China, the positive rate of the diagnosis of ASFV by qPCR with the LPR and commercial kit reached 80.73% (176/218) and 76.61% (167/218) respectively. The coincidence rate between the two assays is 92.20% (201/218), and kappa value is 0.768 (p <.0001) by SPSS analysis. The overall agreement between the two assays was 95.87% (209/218). Further Pearson correlation and linear regression analysis showed a significant correlation between the two assays with an R2 value of 0.9438. The entire procedure, from specimen processing to result reporting, can be completed within 2 hr. Our results demonstrated that the qPCR‐LPR assay is a good laboratory diagnostic tool for sensitive and efficient detection of ASFV. [ABSTRACT FROM AUTHOR]

Background Abnormal gut barrier function is the basis of gut inflammatory disease. It is known that house dust mite (HDM) aero-allergens induce inflammation in respiratory mucosa. We have recently reported allergen from Dermatophagoides pteronyssinus (Der p1) to be present in rodent gut. Objective To examine whether Der p1 is present in human gut and to assess its effect on gut barrier function and inflammation. Design Colonic biopsies, gut fluid, serum and stool were collected from healthy adults during endoscopy. Der p1 was measured by ELISA. Effect of HDM was assessed on gut permeability, tight-junction and mucin expression, and cytokine production, in presence or absence of cysteine protease inhibitors or serine protease inhibitors. In vivo effect of HDM was examined in mice given oral HDM or protease-neutralised HDM. Role of HDM in low-grade inflammation was studied in patients with IBS. Results HDM Der p1 was detected in the human gut. In colonic biopsies from healthy patients, HDM increased epithelial permeability (p<0.001), reduced expression of tight-junction proteins and mucus barrier. These effects were associated with increased tumour necrosis factor (TNF)-α and interleukin (IL)-10 production and were abolished by cysteine-protease inhibitor ( p<0.01). HDM effects did not require Th2 immunity. Results were confirmed in vivo in mice. In patients with IBS, HDM further deteriorated gut barrier function, induced TNF-α but failed to induce IL-10 secretion (p<0.001). Conclusions HDM, a ubiquitous environmental factor, is present in the human gut where it directly affects gut function through its proteolytic activity. HDM may be an important trigger of gut dysfunction and warrants further investigation. [ABSTRACT FROM AUTHOR]

The formation of extracellular traps (ETs) has recently been recognized as a novel defense mechanism in several types of innate immune cells. It has been suggested that these structures are toxic to microbes and contribute significantly to killing several pathogens. However, the role of ETs formed by macrophages (METs) in defense against microbes remains little known. In this study, we demonstrated that a subset of murine J774A.1 macrophage cell line (8% to 17%) and peritoneal macrophages (8.5% to 15%) form METs-like structures (METs-LS) in response to Escherichia coli and Candida albicans challenge. We found only a portion of murine METs-LS, which are released by dying macrophages, showed detectable killing effects on trapped E. coli but not C. albicans. Fluorescence and scanning electron microscopy analyses revealed that, in vitro, both microorganisms were entrapped in J774A.1 METs-LS composed of DNA and microbicidal proteins such as histone, myeloperoxidase and lysozyme. DNA components of both nucleus and mitochondrion origins were detectable in these structures. Additionally, METs-LS formation occurred independently of ROS produced by NADPH oxidase, and this process did not result in cell lysis. In summary, our results emphasized that microbes induced METs-LS in murine macrophage cells and that the microbicidal activity of these METs-LS differs greatly. We propose the function of METs-LS is to contain invading microbes at the infection site, thereby preventing the systemic diffusion of them, rather than significantly killing them. [ABSTRACT FROM AUTHOR]

The enteric pathogen Salmonella enterica serovar Typhimurium causes food poisoning resulting in gastroenteritis. The S. Typhimurium effector Salmonella invasion protein A (SipA) promotes gastroenteritis by functional motifs that trigger either mechanisms of inflammation or bacterial entry. During infection of intestinal epithelial cells, SipA was found to be responsible for the early activation of caspase-3, an enzyme that is required for SipA cleavage at a specific recognition motif that divided the protein into its two functional domains and activated SipA in a manner necessary for pathogenicity. Other caspase-3 cleavage sites identified in S. Typhimurium appeared to be restricted to secreted effector proteins, which indicates that this may be a general strategy used by this pathogen for processing of its secreted effectors.

Acrylic acid is a kind of important monomer and basic organic chemical raw material. In the process of catalytic preparation of acrylic acid from lactic acid, in order to monitor the catalytic process effectively and timely, an anion-exchange chromatographic (AEC) method has been established for the simultaneous determination of lactic acid and acrylic acid. The separation was carried out on a Metrohm A Supp 5 anion-exchange column (150 mm x 4.0 mm) with 2 mmol/L Na2CO3 +2 mmol/L NaHCO3 as the mobile phase. The flow rate of the mobile phase was 0.7 mL/min. A chemically suppressed conductivity detector was used. The linear ranges of calibration curves were 0.1-500 mg/L for lactic acid and 0.1-200 mg/L for acrylic acid. The detection limits with S/N = 3 were 0.030 mg/L for lactic acid and 0. 035 mg/L for acrylic acid. The recoveries of lactic acid and acrylic acid were 100.7%-106% and 99.6%-103% with the relative standard deviations of 2.16%-2.49% and 2.42%-2.48%, respectively. This method is accurate, speedy, sensitive and reproducible, and has been successfully used for the determination of lactic acid and acrylic acid in the catalytic reaction product.