Subjects: Nuclear Science and Technology >> Other Disciplines of Nuclear Science submitted time 2024-05-08
Abstract: 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.
Subjects: Nuclear Science and Technology >> Nuclear Science and Technology submitted time 2023-12-10
Abstract: X-ray photon correlation spectroscopy (XPCS) has emerged as a powerful tool for probing the nanoscale
dynamics of soft condensed matter and strongly correlated materials owing to its high spatial resolution and
penetration capabilities. This technique requires high brilliance and beam coherence, which are not directly
available at modern synchrotron beamlines in China. To facilitate future XPCS experiments, we modified the
optical setup of the newly commissioned BL10U1 USAXS beamline at the Shanghai Synchrotron Radiation
Facility (SSRF). Subsequently, we performed XPCS measurements on silica suspensions in glycerol, which
were opaque owing to their high concentrations. Images were collected using a high frame rate area detector.
A comprehensive analysis was performed, yielding correlation functions and several key dynamic parameters.
All the results were consistent with the theory of Brownian motion and demonstrated the feasibility of XPCS at
SSRF. Finally, by carefully optimizing the setup and analyzing the algorithms, we achieved a time resolution of
2 ms, which enabled the characterization of millisecond dynamics in opaque systems.
Subjects: Physics >> Nuclear Physics submitted time 2023-07-06
Abstract: Proton computed tomography (CT) has a distinct practical significance in clinical applications. It eliminates 3–5% errors caused by the transformation of Hounsfield unit (HU) to relative stopping power (RSP) values when using X-ray CT for positioning and treatment planning systems (TPSs). Following the development of FLASH proton therapy, there are increased requirements for accurate and rapid positioning in TPSs. Thus, a new rapid proton CT imaging mode is proposed based on sparsely sampled projections. The proton beam was boosted to 350 MeV by a compact proton linear accelerator (linac). In this study, the comparisons of the proton scattering with the energy of 350 MeV and 230 MeV are conducted based on GEANT4 simulations. As the sparsely sampled information associated with beam acquisitions at 12 angles 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 on Monte Carlo simulations. Considering the estimation of the most likely path (MLP), the prior image-constrained compressed sensing (PICCS) algorithm is used to reconstruct images from two different phantoms using sparse proton projections of 350 MeV parallel proton beam. The results show that it is feasible to realize the proton image reconstruction with the rapid proton CT imaging proposed in this paper. It can produce RSP maps with much higher accuracy for TPSs and fast positioning to achieve ultra-fast imaging for real-time image-guided radiotherapy (IGRT) in clinical proton therapy applications.