分类: 核科学技术 >> 核材料与工艺技术 提交时间: 2023-06-18 合作期刊: 《Nuclear Science and Techniques》
摘要: A macroporous silica-based silver loaded adsorbent was synthesized by grafting the silver complexes of thiourea (Ag(tu)3NO3) into a silica-based copolymer support (SiO2-P). The adsorbent was used to uptake iodide anions (I-) by batch and column techniques. The kinetic and saturated adsorption experiments were carried out by varying the shaking times and initial concentration of I-. The experiments found that the kinetic adsorption of I- was controlled by a pseudo second order model and the saturated adsorption of I- was controlled by the chemisorption mechanism, which followed a Langmuir adsorption equation. The breakthrough curve of I- had a S-shaped profile. The column efficiency was estimated to be over 90%.
分类: 核科学技术 >> 辐射物理与技术 提交时间: 2023-06-01
摘要: In recent years, graphics processing units (GPUs) have been applied to accelerate Monte Carlo (MC) simulations for proton dose calculation in radiotherapy. Nonetheless, current GPU platforms, such as CUDA and OpenCL, suffer from cross-platform limitation or relatively high programming barrier. However, the Taichi toolkit, which was developed to overcome these difficulties, has been successfully applied to high-performance numerical computations. Based on the class II condensed history simulation scheme with various proton-nucleus interactions, we developed a proton MC transport GPU-accelerated engine using the Taichi toolkit. Dose distributions in homogeneous and heterogeneous materials were calculated for 110, 160, and 200 MeV protons and were compared with those obtained by full MC simulations using Topas. The gamma passing rates were greater than 0.99 and 0.95 with criteria of 2 mm, 2% and 1 mm, 1%, respectively, in all the tested conditions. Moreover, the calculation speed was at least 5800 times faster than that of Topas, and the number of lines of code was approximately 10 times lesser than those of CUDA or OpenCL. Our study provides a highly accurate, efficient, and easy-to-use proton dose calculation engine for algorithm developers, students, and medical physicists.
分类: 材料科学 >> 材料科学(综合) 提交时间: 2023-12-05
摘要: This study synthesized copper-substituted lead apatite using the hydrothermal method, starting from hydroxyapatite precursors. For stability, it is recommended to maintain copper substitution below x=2 in the Pb10-xCux(PO4)O apatite. The introduction of copper appropriately reduces the lattice constant, in line with DFT theoretical calculations. Non-equilibrium heat treatment introduces additional charge carriers; oxygen-rich tempering shifts the sample to paramagnetism, while anaerobic tempering leads to complex and unique hysteresis loops. Non-equilibrium annealing can increase carrier concentration, but its efficacy is limited. Although some improvements have been observed, further exploration involving additional element doping or seeking interfaces with suitable conductive phases is needed to achieve superconductivity.
分类: 生物学 >> 生物物理学 提交时间: 2016-05-12
摘要: The NLR family apoptosis inhibitory proteins (NAIPs) bind conserved bacterial ligands, such as the bacterial rod protein PrgJ, and recruit NLR family CARD-containing protein 4 (NLRC4) as the inflammasome adapter to activate innate immunity. We found that the PrgJ-NAIP2-NLRC4 inflammasome is assembled into multisubunit disk-like structures through a unidirectional adenosine triphosphatase polymerization, primed with a single PrgJ-activated NAIP2 per disk. Cryo-electron microscopy (cryo-EM) reconstruction at subnanometer resolution revealed a similar to 90 degrees hinge rotation accompanying NLRC4 activation. Unlike in the related heptameric Apaf-1 apoptosome, in which each subunit needs to be conformationally activated by its ligand before assembly, a single PrgJ-activated NAIP2 initiates NLRC4 polymerization in a domino-like reaction to promote the disk assembly. These insights reveal the mechanism of signal amplification in NAIP-NLRC4 inflammasomes.