Vol.31,

Ischemic stroke is one of the leading causes of death worldwide, and effective treatment strategies in the chronic phase of this disease remain insufficient. Homeostasis of metals in the brain plays an important role in maintaining normal brain function. However, the dynamic spatial distributions of iron, zinc, calcium, potassium, and copper in a rat brain following ischemic stroke and the association between structural distribution and function remain to be elucidated. In this study, we used a synchrotron radiation-based micro-X-ray fluorescence technique to image element mapping changes in special rat brain regions after ischemic stroke, showing the distribution characteristics of iron, zinc, calcium, potassium, and copper. We demonstrated, for the first time, the consistent dynamic spatial distributions of metal elements at a series of time points (3 h, 4.5 h, 6 h, 12 h, 1 d, 3 d, 5 d, 7 d, 10 d, 14 d, 28 d) after brain ischemia, which revealed that the homeostasis of iron, zinc, calcium, potassium, and copper in the brain was disturbed with distinctive change trends, providing clear insights in understanding the underlying pathogenesis of stroke from a novel perspective, thus laying the foundation of further developing new drug targets for stroke treatment.

505

The SC200 proton therapy system commissioned by the Hefei CAS Ion Medical and Technical Devices Co., Ltd. (HFCIM; Hefei, China) and the Joint Institute for Nuclear Research (JINR; Dubna, Russia) has made significant progress. A main radial beam diagnostic system (MRBDS) equipped with a new type of train probe was developed to satisfy the requirements of beam diagnosis. In this paper, the detailed design of the mechanical structure and electronics system of the MRBDS is presented. The electronics system, which includes hardware and software components, was tested and calibrated. The results show that measurement errors can be significantly reduced by the designed calibration procedures. The repeatability of the mechanical structure was also verified, and the experimental results indicate that the unidirectional repeatability of the positioning is better than 0.3 mm. Finally, the MRBDS was used to measure the phase lag of the particles in the beam, and the results showed a high degree of agreement with theoretical calculations, which proved the applicability and high efficiency of the MRBDS.

477

Silicon microstrip detectors are widely used in experiments for space astronomy. Before the detector is assembled, extensive characterization of the silicon microstrip sensors is indispensable and challenging. This work electrically evaluates a series of sensor parameters, including the depletion voltage, bias resistance, metal strip resistance, total leakage current, strip leakage current, coupling capacitance, and interstrip capacitance. Two methods are used to accurately measure the strip leakage current, and the test results match each other well. In measuring the coupling capacitance, we extract the correct value based on a SPICE model and two-port network analysis. In addition, the expression of the measured bias resistance is deduced based on the SPICE model.

585

The irradiation behavior of graphite is essential for its applications in the nuclear industry. However, the behavioral differences of graphite remain obscure because of the very limited comprehension of its microstructural differences. One typical structure, the quinoline insoluble (QI) particle, was investigated using IG-110 and NBG-18 graphite. After irradiation, the QI particles on the polished surface were proven to become hillocks, which were easily identifiable via scanning electron microscopy (SEM). Thus, a method that combined ion irradiation and SEM characterization was proposed to study the distribution and concentration of QI particles in graphite. During irradiation, the QI particles were found to evolve into densified spheres, which were weakly bonded with the surrounding graphite structures, thereby indicating that the densification of QI particles did not evidently contribute to graphite dimensional shrinkage. A much higher concentration of QI particles in NBG-18 than IG-110, which was suggested to be responsible for the smaller maximum dimensional shrinkage of former over the latter during irradiation, was characterized.

634

The digital reactor protection system (RPS) is one of the most important digital instrumentation and control (I&C) systems utilized in nuclear power plants (NPPs). It ensures a safe reactor trip when the safety-related parameters violate the operational limits and conditions of the reactor. Achieving high reliability and availability of digital RPS is essential to maintaining a high degree of reactor safety and cost savings. The main objective of this study is to develop a general methodology for improving the reliability of the RPS in NPP, based on a Bayesian Belief Network (BBN) model. The structure of BBN models is based on the incorporation of failure probability and downtime of the RPS I&C components. Various architectures with dual state nodes for the I&C components were developed for reliability sensitive analysis and availability optimization of the RPS and to demonstrate the effect of I&C components on the failure of the entire system. A reliability framework clarified as a Reliability Block Diagram (RBD) transformed into a BBN representation was constructed for each architecture to identify which one will fit the required reliability. The results showed that the highest availability obtained using the proposed method was 0.9999998. There are 120 experiments using two common component importance measures that are applied to define the impact of I&C modules, which revealed that some modules are more risky than others and have a larger effect on the failure of the digital RPS.

653

The LaBr₃(Ce) detector has attracted much attention in recent years because of its superior characteristics compared with other scintillating materials in terms of resolution and efficiency. However, it has a relatively high intrinsic background radiation because of the naturally occurring radioisotopes in lanthanum, actinium, and their daughter nuclei. This limits its applications in low-counting rate experiments. In this study, we identified the radioactive isotopes in the ϕ3" × 3" Saint-Gobain B380 detector by a coincidence measurement using a Clover detector in a low-background shielding system. Moreover, we carried out a Geant4 simulation of the experimental spectra to evaluate the activities of the main internal radiation components. The total activity of the background radiation of B380 is determined to be 1.523 (34) Bq/cm³. The main sources include ¹³⁸La at 1.428 (34) Bq/cm³, ²⁰⁷Tl at 0.0135 (13) Bq/cm³, ²¹¹Bi at 0.0136 (15) Bq/cm³, ²¹⁵Po at 0.0135 (3) Bq/cm³, ²¹⁹Rn at 0.0125 (12) Bq/cm³, ²²³Fr at 0.0019 (11) Bq/cm³, ²²³Ra at 0.0127 (10) Bq/cm³, ²²⁷Th at 0.0158 (22) Bq/cm³, and ²²⁷Ac at 0.0135 (13) Bq/cm³. Of these, the activities of ²⁰⁷Tl, ²¹¹Po, ²¹⁵Po, ²²³Fr, and ²²⁷Ac are deduced for the first time from the secular equilibrium established in the decay chain of ²²⁷Ac.

512

This paper describes the design and preliminary test of the low-level radio frequency (LLRF) part of the C band high-gradient test facility for the Shanghai Soft X-ray Free-Electron Laser (SXFEL)-Linear Accelerator (LINAC). Before installation, the accelerating structures should be tested and conditioned. During the conditioning process, breakdown detection is needed to protect the accelerating structures and klystron from damage. The PCI extensions for instrumentation-based LLRF system and auto-conditioning algorithm are designed and applied in the LLRF part of the C band high-gradient test facility. 3 C band accelerating structures and 1 pulse compressor have completed conditioning and were installed in the SXFEL-LINAC.

558

This paper introduces some latest developments regarding the X-ray imaging methodology and applications of the X-ray imaging and biomedical application beamline (BL13W1) at the Shanghai Synchrotron Radiation Facility in the past five years. The photon energy range of the beamline is 8–72.5 keV. Several sets of X-ray imaging detectors with different pixel sizes (0.19–24 μm) are used to realize X-ray microcomputed tomography (X-ray micro-CT) and X-ray in-line phase-contrast imaging. To satisfy the requirements of user experiments, new X-ray imaging methods and image processing techniques are developed. In vivo dynamic micro-CT experiments with living insects are performed in 0.5 s (sampling rate of 2 Hz, 2 tomograms/s) with a monochromatic beam from a wiggler source and in 40 ms (sampling rate of 25 Hz, 25 tomograms/s) with a white beam from a bending magnet source. A new X-ray imaging method known as move contrast X-ray imaging is proposed, with which blood flow and moving tissues in raw images can be distinguished according to their moving frequencies in the time domain. Furthermore, X-ray speckle-tracking imaging with twice exposures to eliminate the edge enhancement effect is developed. A high-precision quantification method is realized to measure complex three-dimensional blood vessels obtained via X-ray micro-CT. X-ray imaging methods, such as three-dimensional X-ray diffraction microscopy, small-angle X-ray scattering CT, and X-ray fluorescence CT are developed, in which the X-ray micro-CT imaging method is combined individually with other contrast mechanisms such as diffraction, scattering, and fluorescence contrasts. Moreover, an X-ray nano-CT experiment is performed with a 100 nm spatial resolution. Typical user experimental results from the fields of material science, biomedicine, paleontology, physics, chemistry, and environmental science obtained on the beamline are provided.

641

Rhenium-188 is prospectively effective for both diagnosis and radiotherapy as it appropriately emits gamma rays and beta particles. Lacosamide (LCM) is a newly approved anti-epileptic medication for focal drug-resistant epilepsy. Rhenium-188 was separated with high elution yield and high purity using the new ¹⁸⁸W/¹⁸⁸Re generator based on the ZrSiW gel matrix. ¹⁸⁸Re-LCM was prepared with high radiochemical yield and high purity. Biodistribution of ¹⁸⁸Re-LCM in normal Swiss albino mice was investigated to determine its utility as a potential brain therapy agent. The ¹⁸⁸W/¹⁸⁸Re generator was used to obtain ¹⁸⁸Re based on the ZrSi¹⁸⁸W gel matrix, and the chemical, radiochemical, and radionuclidic purity of the obtained ¹⁸⁸Re was determined using inductively coupled plasma optical emission spectrometry (ICP-AES), a paper chromatography technique, and high-purity germanium (HPGe) detection, respectively, to assess its validity for LCM labeling. Various factors, such as the pH, reaction time, and LCM quantity, were therefore studied in order to improve the yield and purity of ¹⁸⁸Re-LCM, as determined by various chromatographic techniques such as electrophoresis, thin layer chromatography (TLC), and high-pressure liquid chromatography (HPLC). ¹⁸⁸Re was obtained with a high elution yield (75±3%) and a low ¹⁸⁸W breakthrough (0.001±0.0001%). The maximum radiochemical yield of ¹⁸⁸Re-LCM (87.5±1.8%) was obtained using 50 μl LCM (4 mM), 250 μl stannous chloride (4.4 mM) at pH 4, 100 μl ¹⁸⁸Re (37 MBq), within 30 min, at room temperature (25±3 °C), as determined by TLC, electrophoresis, and HPLC techniques. Biodistribution analysis showed that ¹⁸⁸Re-LCM was primarily localized in the brain (5.1%) with a long residence time (240 min).

671

In the process of in situ leaching of uranium, the microstructure controls and influences the flow distribution, percolation characteristics, and reaction mechanism of lixivium in the pores of reservoir rocks, and directly affects the leaching of useful components. In this study, the pore throat, pore size distribution, and mineral composition of low-permeability uranium-bearing sandstone were quantitatively analyzed by high pressure mercury injection (HPMI), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), and wavelength dispersive X-ray fluorescence (WD-XRF). The distribution characteristics of pores and minerals in the samples were qualitatively analyzed using energy dispersive scanning electron microscopy (EDS-SEM) and multi-resolution CT images. Image registration with the landmarks algorithm provided by FEI Avizo was used to accurately match the CT images with different resolutions. The multi-scale and multi-mineral digital core model of low-permeability uranium-bearing sandstone is reconstructed through pore segmentation and mineral segmentation of fusion core scanning images. The results show that the pore structure of low-permeability uranium-bearing sandstone is complex and has multi-scale and multi-crossing characteristics. The intergranular pores determine the main seepage channel in the pore space, and the secondary pores have poor connectivity with other pores. Pyrite and coffinite are isolated from the connected pores and surrounded by a large number of clay minerals and ankerite cements, which increases the difficulty of uranium leaching. Clays and a large amount of ankerite cement filled in the primary and secondary pores and pore-throats of the low-permeability uranium-bearing sandstone, which significantly reduces the porosity of the movable fluid and results in low overall permeability of the cores. The multi-scale and multi-mineral digital core proposed in this study provides a basis for characterizing macroscopic and microscopic pore-throat structures and mineral distributions of low-permeability uranium-bearing sandstone, and can better understand the seepage characteristics.

686