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During the decommissioning of the 101 reactor hot cell, there are some problems, such as high radiation level, small space, complex environment, etc. In order to complete the recovery of radioactive waste, decommissioning robot system was designed. The experimental verification of waste recovery was carried out on the platform of simulated hot cell. The results show that the robot is driven by hydraulic pressure and has 6 degrees of freedom. The load capacity of the robot is up to 30 kg under the condition of maximum arm span. In the bench examination, the decommissioning robot has high reachability, which can realize the recovery of the waste from the storage well and the ground of the hot cell. The decommission robot design is reasonable and the function can meet the requirements of the hot cell decommissioning. The results can provide technical support for the actual implementation of the project.

The calculation and visualization of the dose field in the decommissioning of nuclear facilities is one of the important functions of the decommissioning virtual simulation system. The dose field simulation tools can provide radiation field distribution and play an important role in determining the decommissioning plan and protecting personnel during the engineering implementation process. This article investigates the development of dose field calculation and visualization in the reactor decommissioning virtual simulation systems. A preliminary technology plan suitable for the development of the decommissioning dose field calculation and visualization display programs of the first Heavy Water Research Reactor (HWRR) in China is proposed. The applicability of the selected scheme is analyzed. The functional requirement and development direction of the HWRR reactor decommissioning dose field tool are preliminarily determined. Furthermore, the reactor vessel of HWRR reactor is modeled, the dose field distribution is calculated and visualized based on the preliminary decommissioning code. This research can provide technical support for the development of the decommissioning simulation system for the first HWRR reactor in China.

ObjectiveTo determine the levels of tetracycline antibiotic residues in eggs and chicken sold on the market in Hangzhou， the pollution sources were explored， and their dietary exposure risk was evaluated.MethodsA total of 66 chicken and 71 egg samples were randomly collected from Hangzhou in 2021 for the detection of tetracycline antibiotics by ultra performance liquid chromatography-tandem mass spectrometry， including tetracycline， oxytetracycline， aureomycin， and doxycycline. The risk of tetracycline antibiotic residues in samples was evaluated by food safety index.ResultsThe detection rate of doxycycline and oxytetracycline in chicken samples were 45.4% and 1.52%， respectively. Tetracycline and aureomycin residues were not detected， and no samples exceeded the standards. Of the four antibiotics， only doxycycline residues were detected in egg samples， and the detection rate and over standard rate were both 1.41%. The overall food safety indices of four tetracyclines were less than one， indicating that eggs and chicken in Hangzhou were safe for consumption.ConclusionTetracycline antibiotics residues were found in eggs and chicken in Hangzhou， while the overall contamination level was low. The safety status of eggs and chicken in Hangzhou was thus considered acceptable.

Abstract Commercialization of Zn‐metal anodes with low cost and high theoretical capacity is hindered by the poor reversibility caused by dendrites growth, side reactions, and the slow Zn2+‐transport and reaction kinetics. Herein, a reversible heterogeneous electrode of Zn‐nanocrystallites/polyvinyl‐phosphonic acrylamide (Zn/PPAm) with fast electrochemical kinetics is designed for the first time: phosphonic acid groups with strong polarity and chelation effect ensure structural reversibility and stability of the three‐dimensional Zn‐storage‐host PPAm network and the Zn/PPAm hybrid; hydrophobic carbon chains suppress side reactions such as hydrogen evolution and corrosion; weak electron‐donating amide groups constitute Zn2+‐transport channels and promote “desolvation” and “solvation” effects of Zn2+ by dragging the PPAm network on the Zn‐metal surface to compress/stretch during Zn plating/stripping, respectively; and the heterostructure and Zn nanocrystallites suppress dendrite growth and enhance electrochemical reactivity, respectively. Thus, the Zn/PPAm electrode shows cycle reversibility of over 6000 h with a hysteresis voltage as low as 31 mV in symmetrical cells and excellent durability and flexibility in fiber‐shaped batteries.

Epigenetically targeted therapeutic development, particularly for SAM-dependent methylations of DNA, mRNA and histones has been proceeding rapidly for cancer treatments over the past few years. However, this approach has barely begun to be exploited for developing new antibiotics, despite an overwhelming global need to counter antimicrobial resistance. Here, we explore whether SAM analogues, some of which are in (pre)clinical studies as inhibitors of human epigenetic enzymes, can also inhibit Clostridioides difficile-specific DNA adenine methyltransferase (CamA), a sporulation regulator present in all C. difficile genomes sequenced to date, but found in almost no other bacteria. We found that SGC0946 (an inhibitor of DOT1L), JNJ-64619178 (an inhibitor of PRMT5) and SGC8158 (an inhibitor of PRMT7) inhibit CamA enzymatic activity in vitro at low micromolar concentrations. Structural investigation of the ternary complexes of CamA-DNA in the presence of SGC0946 or SGC8158 revealed conformational rearrangements of the N-terminal arm, with no apparent disturbance of the active site. This N-terminal arm and its modulation of exchanges between SAM (the methyl donor) and SAH (the reaction product) during catalysis of methyl transfer are, to date, unique to CamA. Our work presents a substantial first step in generating potent and selective inhibitors of CamA that would serve in the near term as chemical probes to investigate the cellular mechanism(s) of CamA in controlling spore formation and colonization, and eventually as therapeutic antivirulence agents useful in treating C. difficile infection.

Abstract An interesting phenomenon that the photocurrent (the difference between illumination and dark current) of a ZnO nanowire (NW) under a specified voltage increased as its length increased in a certain range was observed previously and it was supposed to be mainly due to a special mean free path effect (MFPE) which caused a special distribution of dark electron density along the length with two higher electron density regions near the two ends of the NW, respectively, and the lower one in the middle part. However, such an explanation would be unreasonable and the true reasons should be the growing-process caused variation of the oxygen adsorption capacity along the NW length and the length-dependent lifetime of photogenerated carriers. Based on this understanding, a theoretical model to properly explain this phenomenon is proposed and the calculation results are in good agreement with the experimental data. This work has introduced an improved insight into the theory of the length-dependent photoelectric property of ZnO NWs.