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 >> 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： The electrochemical properties of perrhenate were studied in hydrochloric acid solution via cyclic voltammetry by disk glassy carbon electrode. The electroreduction of perrhenate was performed at a constant potential -0.33 V (vs. Ag/AgCl) with a potentiostat by a flow type electrolysis cell. It was found that the change of rhenium ion concentration before and after electrolysis was negligible. This means almost no rhenium or rhenium oxides were deposited on the carbon fiber electrode during the electroreduction. The rhenium ion solution changed from colorless into yellow-brown after electrolysis process. UV-Visible spectrophotometry was used to characterize the oxidation states of Re before and after electrolysis. Some obvious peaks were detected after electrolysis, indicating that Re(VII) was reduced to Re(V). The complex behavior and stability of Re(V)-HEDP were discussed for the purpose of electroreduction of Re(VII) or Tc(VII) on radiopharmaceuticals production.
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： The influence of acetate on U(VI) sorption on silica from aqueous solutions was studied at pH 27 by complementary experimental methods of macroscopic measurement, spectroscopic investigation and thermodynamic calculation. Sorption percentage of U(VI) in the absence and in the presence of different acetate concentrations was determined by batch sorption procedures. Attenuated total reflection Fourier transform infra-red spectroscopy (ATR-FTIR) was used to elucidate the mechanisms of uranyl sorption on silica in the presence of acetate, by investigating, in-situ, the changes in the U(VI) sorption on silica surface in presence of ligand: the absorption bands of carboxylate (COO) in the range 13001700 cm-1 and those around 850950 cm-1 of uranyl species as(UO2) are followed. The decrease of U(VI) sorption with increasing acetate concentration was observed. Sorption of U(VI)-acetate (U-Ac) species on silica surface was demonstrated for the first time. ATR-FTIR investigations clearly evidenced the absorption bands characteristic of sorbed U-Ac complexes both from the acetate and uranyl spectral regions those the wavenumbers correspond to sorbed species. No sequence effect of acetate and uranyl on the sorption on silica in ternary systems U(VI)-acetate-silica was observed from the sorption data. From the ATR-FTIR investigations, we can induce that the sorption of U-Ac leads to chemical equilibria and makes possible the modeling of sorption isotherms by surface complexation models. The related thermodynamic constants were modeled using CCM surface complexation modeling.
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： The electrochemical behavior of Pd(II) and Rh(III) in [EMIm]NTf2 ionic liquid has been studied on Pt working electrodes at 298 K by cyclic voltammetry (CV), polarization curve and galvanostatic transient techniques. Cyclic voltammogram of Pd(II) in [EMIm]NTf2 consists of two cathodic current peaks located at 1.37 V(Epc2), corresponding to Pd2+/Pd+, and at 0.69 V (Epc1) corresponding to Pd+/Pd. The transfer coefficient was calculated by the Tafel extrapolation from the polarization curves to be 0.306, which is in agreement with the value reported in an aqueous solution system. For Rh(III) in [EMIm]NTf2, a cathodic current peak (Epc) was observed at -0.39 V, corresponding to Rh3+/Rh, and two oxidation peaks were observed at -0.13 V (Epa1) and 0.37 V (Epa2) during the reverse scan. A significantly negative shift in the cathodic peak potential was observed with the increase of the scan rate, indicating that the reduction of Pd(II) and Rh(III) on the Pt electrode involves kinetic complications. By using the galvanostatic transient technique, the diffusion coefficients of Pd(II) and Rh(III) in [EMIm]NTf2 ionic liquid solution were found to be 10-7 cm2/s. The potential difference between the reduction of Pd(II) to Pd and the reduction of Rh(III) to Rh obtained from the CV curves of the Pd(II) and Rh(III) co-existing [EMIm]NTf2 solution is found to be about 0.74 V, which makes it possible to electrodeposit Pd(II) and Rh(III) separately.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： With the advent of gravitational-wave astronomy and the discovery of more compact binary coalescences, data quality improvement techniques are desired to handle the complex and overwhelming noise in gravitational wave (GW) observational data. Though recent studies have shown promising results for data denoising, they are unable to precisely recover both the GW signal amplitude and phase. To address such an issue, we develop a deep neural network centered workflow, WaveFormer, for significant noise suppression and signal recovery on observational data from the Laser Interferometer Gravitational-Wave Observatory (LIGO). The WaveFormer has a science-driven architecture design with hierarchical feature extraction across a broad frequency spectrum. As a result, the overall noise and glitch are decreased by more than 1 order of magnitude and the signal recovery error is roughly 1% and 7% for the phase and amplitude, respectively. Moreover, we achieve state-of-the-art accuracy on reported binary black hole events of existing LIGO observing runs and substantial 1386 years inverse false alarm rate improvement on average. Our work highlights the potential of large neural networks for GW data quality improvement and can be extended to the data processing analyses of upcoming observing runs.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： With the advent of gravitational-wave astronomy and the discovery of more compact binary coalescences, data quality improvement techniques are desired to handle the complex and overwhelming noise in gravitational wave (GW) observational data. Though recent studies have shown promising results for data denoising, they are unable to precisely recover both the GW signal amplitude and phase. To address such an issue, we develop a deep neural network centered workflow, WaveFormer, for significant noise suppression and signal recovery on observational data from the Laser Interferometer Gravitational-Wave Observatory (LIGO). The WaveFormer has a science-driven architecture design with hierarchical feature extraction across a broad frequency spectrum. As a result, the overall noise and glitch are decreased by more than 1 order of magnitude and the signal recovery error is roughly 1% and 7% for the phase and amplitude, respectively. Moreover, we achieve state-of-the-art accuracy on reported binary black hole events of existing LIGO observing runs and substantial 1386 years inverse false alarm rate improvement on average. Our work highlights the potential of large neural networks for GW data quality improvement and can be extended to the data processing analyses of upcoming observing runs.
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： To isolate and separate thorium from nitric acid solutions, three silica-based anion exchange resins were synthesized. Batch experiments were carried out to investigate adsorption behavior of thorium in nitric acid solutions. Adsorption at different concentrations of nitric acid and thorium, influence of contact time and coexisting metal ions, and effect of NO3- were investigated in detail. It was found that at high HNO3 concentrations, the resins exhibited higher adsorption capacity and better affinity towards thorium. The adsorption kinetics could be described by the pseudo-second order model equation, while the adsorption isotherms were well correlated by the Langmuir model. The maximum capacity towards thorium species on SiPyR-N4 was evaluated at 2728 mg/g-resin. The thermodynamic parameters indicated the adsorption was an exothermic reaction. The presence of NO3- was found to promote the retention of the thorium species.
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： Extraction behavior of lanthanides (La, Eu, Dy, Lu) from HNO3 solution was studied using a novel extraction system with hydrophobic ionic liquid being diluent and isobutyl-BTP being extractant. Compared with that in isobutyl-BTP/cyclohexane extraction system, application of ionic liquid as the extracting phase provided unprecedented enhancement of the extraction performance of isobutyl-BTP for lanthanides. It was found that the isobutyl-BTP/[Cnmim][NTf2] extraction system is favorable to get good extraction at low acidity condition (isobutyl-BTP/ [Cnmim][NTf2] (n=2, 6, 8) systems, isobutyl-BTP/[C2mim][NTf2] extraction system provides the best extraction performance and fastest extraction kinetics within 5 min towards Dy3+. The extraction is spontaneous endothermic and temperature is good for extraction. The transfer of lanthanides, in isobutyl-BTP/[C2mim][NTf2] extraction system, proceeded via a cation exchange mechanism, in contrast to extraction of neutral complex in the cyclohexane system.
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： The water-soluble radiolytic products of 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide ionic liquid ([C2mim][NTf2]) under -radiation, such as CF3SOOH, CF3SO2NH2, HF, and H2SO3, were identified by using 1H NMR, 19F NMR, and ion chromatography. The extraction behavior of Dy3+ using irradiated [C2mim][NTf2] in combination with 2,6-di(5,6-diisobutyl-1,2,4-triazin-3-yl)pyridine (isobutyl-BTP) was studied and the abnormal increase of Dy3+ partitioning after irradiation is mainly attributed to the precipitation formed between Dy3+ and radiolytic products of [C2mim][NTf2] (F- and SO32-). Washing irradiated [C2mim][NTf2] with water provides a simple method for ionic liquid recycling.
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 new anion exchanger with pyridine groups was prepared by grafting of 2-vinyl pyridine onto polypropylene (PP) nonwoven fabrics by pre-irradiation grafting technique, followed by quaternization of pyridine rings in grafted chains in reaction with bromoethane. The results showed that the grafting yield increased with the monomer concentration and conversion ratio of quaternization increased with the time. The grafted and quaternized fabrics were characterized by FT-IR, DSC, SEM and ICP. The possibility of adsorption of perrhenate (ReO4-), a nonradioactive analogue to pertechnetate (99TcO4-), from aqueous solution by anion exchanger was investigated. The experiments performed at pH= 0.16 showed that pH=2.2 was the optimal acidity for ReO4- adsorption, and an adsorption equilibrium was achieved in 30 min. The reaction enthalpy was -12.55 kJ/mol, indicating that the adsorption process is exothermic. XPS tests indicated that the ReO4- uptake was a typical ion exchange between Cl- on anion exchanger and ReO4-.
分类： 光学 >> 量子光学 提交时间： 2023-02-19
摘要： In this work, the radiation responses of silicon photonic passive devices built in silicon-on-insulator (SOI) technology are investigated through high energy neutron and 60Co gamma-ray irradiation. The wavelengths of both micro-ring resonators (MRRs) and Mach-Zehnder interferometers (MZIs) exhibit blue shifts after high-energy neutron irradiation to a fluence of 1*1012 n/cm2; the blue shift is smaller in MZI devices than in MRRs due to different waveguide widths. Devices with SiO2 upper cladding layer show strong tolerance to irradiation. Neutron irradiation leads to slight changes in the crystal symmetry in the Si cores of the optical devices and accelerated oxidization for devices without SiO2 cladding. A 2 um top cladding of SiO2 layer significantly improves the radiation tolerance of these passive photonic devices.
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： The adsorption behavior of 241Am(III) and Eu(III) by silica/polymer-based isoHex-BTP adsorbent (isoHex-BTP/SiO2-P) was investigated by a batch experiment method. isoHex-BTP/SiO2-P exhibited high affinity and selectivity for 241Am(III) over 152Eu(III) in 24 mol/dm3 nitric acid solutions. Within the experimental contact time range of 0.524 h, isoHex-BTP/SiO2-P showed high selectivity for 241Am(III) compared to 152Eu(III) in 3 mol/dm3 nitric acid solution. However, the adsorption kinetics of 241Am(III) and 152Eu(III) was slow. Eu(III) adsorption followed the pseudo-second-order kinetic model, indicating chemical adsorption as the rate-limiting step of the adsorption process. And the adsorption agreed well with the Langmuir adsorption model at various temperatures. The adsorption kinetics and isotherm data indicated that the equilibrium adsorption capacity, the adsorption rate, the maximum adsorption capacity and the adsorption affinity, increased with temperature. The thermodynamic parameters, negative change in Gibbs free energy, and positive change in enthalpy and entropy, suggested that the adsorption of Eu(III) was spontaneous and endothermic process with an increase of entropy.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
摘要： The proposed space-borne laser interferometric gravitational wave (GW) observatory TianQin adopts a geocentric orbit for its nearly equilateral triangular constellation formed by three identical drag-free satellites. The geocentric distance of each satellite is $\approx 1.0 \times 10^{5} ~\mathrm{km}$, which makes the armlengths of the interferometer be $\approx 1.73 \times 10^{5} ~\mathrm{km}$. It is aimed to detect the GWs in $0.1 ~\mathrm{mHz}-1 ~\mathrm{Hz}$. For space-borne detectors, the armlengths are unequal and change continuously which results in that the laser frequency noise is nearly $7-8$ orders of magnitude higher than the secondary noises (such as acceleration noise, optical path noise, etc.). The time delay interferometry (TDI) that synthesizes virtual interferometers from time-delayed one-way frequency measurements has been proposed to suppress the laser frequency noise to the level that is comparable or below the secondary noises. In this work, we evaluate the performance of various data combinations for both first- and second-generation TDI based on the five-year numerically optimized orbits of the TianQin's satellites which exhibit the actual rotating and flexing of the constellation. We find that the time differences of symmetric interference paths of the data combinations are $\sim 10^{-8}$ s for the first-generation TDI and $\sim 10^{-12}$ s for the second-generation TDI, respectively. While the second-generation TDI is guaranteed to be valid for TianQin, the first-generation TDI is possible to be competent for GW signal detection with improved stabilization of the laser frequency noise in the concerned GW frequencies.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Wei Su
Yan Wang
Chen Zhou
Lingfeng Lu
Ze-Bing Zhou
T. Li
Tong Shi
Xin-Chun Hu
Ming-Yue Zhou
Ming Wang
Hsien-Chi Yeh
Han Wang
P. F. Chen
摘要： TianQin is a proposed space-borne gravitational wave (GW) observatory composed of three identical satellites orbiting around the geocenter with a radius of $10^5$ km. It aims at detecting GWs in the frequency range of 0.1 mHz -- 1 Hz. The detection of GW relies on the high precision measurement of optical path length at $10^{-12}$~m level. The dispersion of space plasma can lead to the optical path difference (OPD, $\Delta l$) along the propagation of laser beams between any pair of satellites. Here, we study the OPD noises for TianQin. The Space Weather Modeling Framework is used to simulate the interaction between the Earth magnetosphere and solar wind. From the simulations, we extract the magnetic field and plasma parameters on the orbits of TianQin at four relative positions of the satellite constellation in the Earth magnetosphere. We calculate the OPD noise for single link, Michelson combination, and Time-Delay Interferometry (TDI) combinations ($\alpha$ and $X$). For single link and Michelson interferometer, the maxima of $|\Delta l|$ are on the order of 1 pm. For the TDI combinations, these can be suppressed to about 0.004 and 0.008 pm for $\alpha$ and $X$. The OPD noise of the Michelson combination is colored in the concerned frequency range; while the ones for the TDI combinations are approximately white. Furthermore, we calculate the ratio of the equivalent strain of the OPD noise to that of TQ, and find that the OPD noises for the TDI combinations can be neglected in the most sensitive frequency range of TQ.
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