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BackgroundLost radioactive sources needs to be quickly retrieved, positioning of radioactive source in complex environment is the key to find the lost radioactive source. [Propose] This study aims to develope a novel approach for the rapid positioning of orphan sources using a NaI(Tl) array detection device.MethodFirst of all, by leveraging the shadow effect between array detectors, a response curve between gamma-ray incidence angles and counts was obtained through the use of Monte Carlo simulation software. Then, the support vector machine (SVM) method was employed to establish a predictive mathematical model for the counting rate of array detectors as a function of gamma-ray incidence angle, utilizing. Finally, a radioactive source localization physical experiment platform was constructed, and a series of incidence angle response experiments were conducted for the validation of this approach applied to radioactive source localization under varying conditions.ResultsEexperimental results demonstrate that, through the use of the SVM regression prediction model, the maximum average deviation of the angle is 9.21° whilst the minimum is 1.77° for the angle prediction of an orphan 137Cs point source.ConclusionsThis method can achieve rapid and accurate localization of an orphan radioactive source.

As one of the most promising alternatives to graphite negative electrodes, silicon oxide (SiOx) has been hindered by its fast capacity fading. Solid electrolyte interphase (SEI) aging on silicon SiOx has been recognized as the most critical yet least understood facet. Herein, leveraging 3D focused ion beam-scanning electron microscopy (FIB-SEM) tomographic imaging, we reveal an exceptionally characteristic SEI microstructure with an incompact inner region and a dense outer region, which overturns the prevailing belief that SEIs are homogeneous structure and reveals the SEI evolution process. Through combining nanoprobe and electron energy loss spectroscopy (EELS), it is also discovered that the electronic conductivity of thick SEI relies on the percolation network within composed of conductive agents (e.g., carbon black particles), which are embedded into the SEI upon its growth. Therefore, the free growth of SEI will gradually attenuate this electron percolation network, thereby causing capacity decay of SiOx. Based on these findings, a proof-of-concept strategy is adopted to mechanically restrict the SEI growth via applying a confining layer on top of the electrode. Through shedding light on the fundamental understanding of SEI aging for SiOx anodes, this work could potentially inspire viable improving strategies in the future. Observing the evolution of the solid electrolyte interphase on SiOx-based electrodes in Li-ion batteries is challenging. Here, authors use three-dimensional tomography to visualize the growth of the interphase on single SiOx particles and propose a mechanical confinement strategy to prevent aging. [ABSTRACT FROM AUTHOR]

Transmission electron microscope (TEM) is thought as one powerful tool to imaging the atomic-level structure of organic inorganic hybrid perovskite (OIHP) materials, which provides valuable and essential guidance toward high performance OIHP-related devices. However, these OIHPs exhibit poor electron beam stability, severely limiting their practical applications in TEM. Here in this article, the application of TEM to obtain atomic-scale image of OIHPs, main obstacles in identifying the degradation product and future prospects of TEM in the characterization of OIHP materials are reviewed and presented. Three potential strategies (sample protection, low temperature technology, and low-dose technologies) are also proposed to overcome the current drawback of TEM technology. [ABSTRACT FROM AUTHOR]

For developing commercially viable LiNi 1- x - y Mn x Co y O 2 (NCM), it is necessary to alleviate the irreversible chemical process upon Li-ion insertion/extraction, which primarily accounts for prevailing capacity loss, impedance buildup as well as low columbic efficiency. To resolve this issue, we herein propose a simple but novel method to alter the chemical composition by a facile treatment of H 2 O 2 , which remarkably reduces the cation mixing of Li + /Ni 2+ and residual lithium on the cathode. The tailored composition contributes great resistance to the structural reconstruction and enhancement in structural reversibility, as shown by in situ Raman and high-resolution transmission electron microscope (HRTEM) results. Thus, the modified sample outperforms the pristine one; it exhibits cyclability with 95.7% capacity retention over 300 cycles, high columbic efficiency and enhanced rate capability., Competing Interests: The authors declare no conflict of interest., (This journal is © The Royal Society of Chemistry.)