分类: 核科学技术 >> 核科学技术其他学科 提交时间: 2024-05-08
摘要: In this study, to efficiently remove Pb(II) from aqueous environments, a novel L-serine-modified polyethylene/polypropylene nonwoven fabric sorbent (NWF-serine) was fabricated through the radiation grafting of glycidyl methacrylate and subsequent L-serine modification. The effect of the absorbed dose was investigated in the range of 5–50 kGy. NWF-serine was characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Batch adsorption tests were conducted to investigate the influences of pH, adsorption time, temperature, initial concentration, and sorbent dosage on the Pb(II) adsorption performance of NWF-serine. The results indicated that Pb(II) adsorption onto NWF-serine was an endothermic process, following the pseudo-second-order kinetic model and Langmuir isotherm model. The saturated adsorption capacity was 198.1 mg/g. NWF-serine exhibited Pb(II) removal rates of 99.8% for aqueous solutions with initial concentrations of 100 mg/L and 82.1% for landfill leachate containing competitive metal ions such as Cd, Cu, Ni, Mn, and Zn. Furthermore, NWF-serine maintained 86% of its Pb(II) uptake after five use cycles. The coordination of the carboxyl and amino groups with Pb(II) was confirmed using X-ray photoelectron spectroscopy and extended X-ray absorption fine structure analysis.
分类: 核科学技术 >> 核科学与技术 提交时间: 2023-12-10
摘要: X-ray photon correlation spectroscopy (XPCS) has emerged as a powerful tool for probing nanoscale dynamics of soft condensed matter and strongly correlated materials, offering high spatial resolution and high penetration capability. This technique requires high brilliance and beam coherence, which are not directly available at modern synchrotron beamlines in China. To pave the way for future XPCS experiments, we first modified the optical setup of the newly commissioned BL10U1 USAXS beamline at the Shanghai Synchrotron Radiation Facility (SSRF). Subsequently, we carried out XPCS measurements on silica suspensions of glycerol, which were opaque in appearance due to high concentrations. Image series were collected by a high frame-rate area detector. Comprehensive analysis was carried out, yielding the correlation functions and several key dynamic parameters. All results agree well with the theory of Brownian motion, demonstrating the feasibility of XPCS at SSRF. Eventually, by carefully optimizing the setup and analyzing algorithms, we achieved a time resolution of 2 ms, enabling characterization of millisecond dynamics in opaque systems.
分类: 物理学 >> 核物理学 提交时间: 2023-07-06
摘要: Proton computed tomography (CT) has a distinct practical significance in clinical applications. It eliminates 35% errors caused by the transformation of Hounsfield unit (HU) to relative stopping power (RSP) valueswhen using X-ray CT for positioning andtreatment planning systems (TPSs). Following the development of FLASH proton therapy, there are increased requirements for accurate and rapid positioning in TPSs. Thus, anewrapid proton CT imaging mode is proposed based on sparsely sampled projections. The proton beam wasboosted to 350 MeV by a compact proton linear accelerator (linac). In this study,thecomparisons of the proton scattering with the energyof 350 MeV and 230 MeV are conducted based on GEANT4simulations.Asthe sparsely sampledinformation associated with beam acquisitions at 12angles is not enough for reconstruction, X-ray CT is used as a prior image. The RSP map generated by converting the X-ray CT was constructed based onMonte Carlo simulations. Consideringtheestimationof the most likely path (MLP), the prior image-constrained compressed sensing (PICCS) algorithm isused to reconstruct images from twodifferent phantoms using sparse protonprojections of 350 MeV parallel proton beam. The results show that it is feasible to realize the proton image reconstruction with the rapid protonCT imaging proposed in this paper. It can produce RSP maps withmuchhigher accuracy for TPSs and fast positioning to achieve ultra-fast imaging for real-time image-guided radiotherapy(IGRT) in clinical proton therapyapplications.