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In special applications such as reactor in-core detection and deep space exploration missions, nuclear detection systems must contend with high-temperature environments. The temperature sensitivity of front-end electronics degrades detection system performance in high temperatures. This study proposes using silicon carbide junction field-effect transistors (SiC-JFETs) as input transistors of preamplifiers to reduce output noise at high temperatures. The theoretical analysis and Technology Computer Aided Design (TCAD) simulation were used to demonstrate how the electrical properties and noise contribution of SiC-JFET change with increasing temperature. Results show that SiC-JFET has a wider operating temperature range and fewer performance variations as the temperature rises from 300 to 675 K when compared to Si-JFET with the same structure. SiC-JFET always has lower noise than Si-JFET when the structures are identical. When the two devices have the same transconductance, SiC-JFET produces less noise at high temperature and long shaping time. Furthermore, the output noise of a nuclear spectrometer with SiC detectors and capacitance-matched JFETs was calculated and analyzed. When the temperature exceeds 324 K or the shaping time is longer than $3.5~\mu \text{s}$ , SiC-JFET can obtain lower noise, and the equivalent noise charge (ENC) reduces thousands of electrons at most. This research lays the groundwork for building SiC-JFET-based charge-sensitive preamplifier (CSA) and front-end circuits with high-temperature resistance and low noise.

In this article, we propose a double-trench-type silicon carbide (SiC) neutron detector and model it using the concept of a unit cell on the GEANT4 platform. When the low-level discriminator (LLD) value was fixed at 300 keV, the structural parameters of this double-trench-type SiC neutron detector were optimized to maximize the intrinsic detection efficiency. Compared with the single trench type, the double-trench-type SiC neutron detector can significantly improve the neutron intrinsic detection efficiency within a limited trench depth, which was especially suitable for the current technological status that SiC materials can only be used for shallow trench etching. Apart from optimizing the structural parameters, the energy deposition spectra in the SiC detector region by the generated secondary charged particles upon thermal neutron interaction in neutron conversion materials ( $^{{10}}\text{B}$ and 6LiF) have also been estimated. It can be found that the double-trench-type SiC neutron detector counts significantly increased in the low-energy range, while the counts in the high-energy range are only slightly decreased. This is also the essential reason why the intrinsic detection efficiency of the double-trench-type SiC neutron detector was significantly improved compared to the single-trench-type SiC neutron detector.

AbstractFast neutron radiography (FNR) has a great potential as a nondestructive technique for testing large objects. A FNR system developed based on a deuterium-tritium neutron generator is presented. Resolution of the FNR system is analyzed using the modulation transfer function (MTF). FNR experiments based on film and charge-coupled device imaging are carried out, respectively. The experimental results of image resolution are compared with the results of MTF calculation. Moreover, the impacts of various system components on signal degradation are discussed in this paper.

ABSTRACTCircular RNAs (circRNAs) are a type of important non-coding RNAs that widely involve in the physiological and pathophysiological process. Recent research has established a link between circHIPK3 and the malignant activity of cancer cells. However, circHIPK3’ role in esophageal squamous cell carcinoma (ESCC) still needs more focus. To determine the prognostic value of circHIPK3 in patients with ESCC, the expression of circHIPK3 was quantified in 32 pairs of ESCC using real-time polymerase chain reaction (RT-qPCR). Then, the correlation between circHIPK3 expression and clinical characteristics of patients was also analyzed. The function of circHIPK3 in the development of ESCC was investigated using cell biology studies and bioinformatics. The results showed that the expression of circHIPK3 was considerably higher in tumor tissues from ESCC patients than that of adjacent tissues, which was associated with a poor prognosis. Additionally, silencing of circHIPK3 expression retarded esophageal cancer cell proliferation, migration and epithelial-mesenchymal transition (EMT) in vitro, as well as the growth in vivo. Mechanistically, we discovered that circHIPK3 behaved like a sponge, absorbing microRNA-124 (miR-124) and promoting serine/threonine kinase 3 (AKT3) expression. Our findings indicate that circHIPK3 acts as an oncogene in ESCC and that the circHIPK3-AKT3axis may be a therapeutic target for patients with ESCC.

Objectives:Resveratrol has been implicated in the differentiation and development of human umbilical cord mesenchymal stem cells. The differentiation of into esophageal fibroblasts is a promising strategy for esophageal tissue engineering. However, the pharmacological effect and underlying mechanism of resveratrol on human umbilical cord mesenchymal stem cells differentiation are unknown. Here, we investigated the effects and mechanism of resveratrol on the differentiation of human umbilical cord mesenchymal stem cells. Methods:Using a transwell-membrane coculture system to culture human umbilical cord mesenchymal stem cells and esophageal fibroblasts, we examined how resveratrol act on the differentiation of human umbilical cord mesenchymal stem cells. Immunocytochemistry, Sirius red staining, quantitative real-time PCR, and Western blotting were performed to examine collagen synthesis and possible signaling pathways in human umbilical cord mesenchymal stem cells. Results:We found that resveratrol promoted collagen synthesis and AKT phosphorylation. However, co-treatment of cells with resveratrol and the PI3K inhibitor LY294002 inhibited collagen synthesis and AKT phosphorylation. We demonstrated that resveratrol down-regulated the expression of IL-6, TGF-β, caspase-9, and Bax by activating the AKT pathway in human umbilical cord mesenchymal stem cell. Furthermore, resveratrol inhibited phosphorylated NF-ĸB in human umbilical cord mesenchymal stem cells. Conclusion:Our data suggest that resveratrol promotes the differentiation of human umbilical cord mesenchymal stem cells into fibroblasts. The underlying mechanism is associated with the downregulation of IL-6 and TGF-β via the AKT pathway and by inhibiting the NF-ĸB pathway. Resveratrol may be useful for esophageal tissue engineering.

Circular RNAs (circRNAs) are novel RNA molecules that play important roles in chemoresistance in different cancers, including breast and gastric cancers. However, whether circRNAs are involved in the response to chemotherapy in small cell lung cancer (SCLC) remains largely unknown. In this study, we observed that cESRP1 (circular RNA epithelial splicing regulatory protein-1) expression was significantly downregulated in the chemoresistant cells compared with the parental chemosensitive cells. cESRP1 enhanced drug sensitivity by repressing miR-93-5p in SCLC. Cytoplasmic cESRP1 could directly bind to miR-93-5p and inhibit the posttranscriptional repression mediated by miR-93-5p, thereby upregulating the expression of the miR-93-5p downstream targets Smad7/p21(CDKN1A) and forming a negative feedback loop to regulate transforming growth factor-β (TGF-β) mediated epithelial-mesenchymal transition. Furthermore, cESRP1 overexpression and TGF-β pathway inhibition both altered tumour responsiveness to chemotherapy in an acquired chemoresistant patient-derived xenograft model. Importantly, cESRP1 expression was downregulated in SCLC patient tissues and was associated with survival. Our findings reveal, for the first time, that cESRP1 plays crucial a role in SCLC chemosensitivity by sponging miR-93-5p to inhibit the TGF-β pathway, suggesting that cESRP1 may serve as a valuable prognostic biomarker and a potential therapeutic target in SCLC patients.

AbstractIn this paper, an online reactor neutron spectrum measurement method is presented. The basic theory of this method is based on the unfolding of few-channel data, in which three miniature ionization chambers are applied. The neutron spectrum can be unfolded with the count rates and response functions of the three detectors through an unfolding program. In order to investigate the feasibility of this method, simulation tests have been performed with the reference neutron spectra and neutron spectra from the China LEAd-based Reactor (CLEAR). The research results show that this method can provide an alternative means for an online neutron spectrum measurement in the reactors. This method is suitable to be applied in fast neutron reactors due to the miniature size of ionization chambers and fission threshold of 238U.