Nuclear Analysis最新文献

Separation and recovery of ¹⁷⁷Lu from radioactive medicine waste is concerned due to its potential application in radiopharmaceuticals. In this paper, two zirconium phosphonate materials (Zr-AMTP-1 and Zr-AMTP-2) were prepared by water-bath and hydrothermal method, respectively, for separating Lu from acidic systems. Both of them exhibited similar sheet-morphology and the typical layered structure like α-ZrP, but Zr-AMTP-2 possessed a wider layered distance due to the existence of [(CH₃)₂NH₂]⁺ in its inter-layers. Remarkably, both two materials exhibited much stronger ability for removal of Lu³⁺ in comparison with α-ZrP, especially in complicated acidic conditions. Notably, Zr-AMTP-2 possess a much higher adsorption capacity for Lu³⁺ (113.91 mg g⁻¹) [almost twice that of Zr-AMTP-1 (60.53 mg g⁻¹)], and quick adsorption rates, which are attributed to its wider layer distance and abundant [(CH₃)₂NH₂]⁺exchange sites. In addition, both two materials have a high selectivity for Lu³⁺ in the mixture solution with the co-existing ions (K⁺, Na⁺ and NO₃⁻). This work posed a new way to develop new adsorbents that could be application in radioactive medicine waste disposal.

A review of the recent works on soft-matters based on small-angle neutron scattering (SANS) is presented. This Review is intended to be a relatively comprehensive source for applying SANS on soft-matters investigation, including the basic principles and theory, the major characteristics of the SANS such as chain labeling and contrast variation/matching based on hydrogen/deuterium replacement, as well as corresponding typical application examples. Through the demonstration of applications in sample systems such as polymer solutions, polymer blend, semi-crystalline polymer, polymer nano-composites, hydrogel, and bio-materials, the advantages of SANS on soft-matters are demonstrated. Specifically, examples of the recent SANS investigation on spectrometer SANS-Suanni of 20 MW China Mianyang Research Reactor (CMRR) were included. As the users of neutron facilities are increasing steeply along with newly established neutron sources as well as experienced ones, this Review is intended to be of interest to the SANS, soft matter, and nano-materials science communities.

Chelidamic acid (denoted as H₃L in this paper) is a naturally occurring derivative of dipicolinic acid that functions as a versatile ligand. The complex formation of chelidamic acid with UO₂²⁺ has been investigated by potentiometry in a 0.1 M NaClO₄ solution. The potentiometry identified 1:1 uranyl–chelidamate complexes (UO₂HL, UO₂L₂⁻), 1:2 uranyl–chelidamate complex (UO₂L₂⁴⁻), and a hydrolytic complex UO₂(OH)₂L²⁻. The possible UO₂H₂L₂²⁻ structure was determine by crystal analysis. Chelidamate molecules coordinate to uranyl mainly through the pyridine–carboxylate chelation pocket (O, N, O), and 4-pyridinol–OH group is protonated. The presence of hydrolysate UO₂(OH)₂L^2– was further confirmed by nuclear magnetic resonance spectroscopy (NMR). In an alkaline aqueous medium under anaerobic conditions, the complex U^VIO₂(OH)₂L²⁻can be electrochemically reduced to pentavalent uranyl.

Crystallization kinetics of polycaprolactone (PCL) with low content of α-cyclodextrin (CD) was investigated. It was found that disordered CD can promote nucleation of PCL significantly after electrospinning, which is possibly related to CD induced slower relaxation of chain deformation. For CDs in the form of channel structure, crystallization of PCL can be either decelerated or accelerated. The opposite trend probably comes from restricted chain diffusion and confinement induced chain extension, respectively, which depends on the distribution of CDs in the initial solution. These results show a simple way to modify chain relaxation and conformation of PCL by blending, which affects the crystallization in different ways.

A visual Small-angle X-ray/neutron scattering data analysis software VSAS has been developed for the quantitative small-angle scattering data processing. VSAS provides a graphical interface which allows visualizing data fitting process to give a smart way to facilitate analysis. Two data processing methods corresponding to the two main functional modes of VSAS are presented, (i) the Guinier and Porod methods, and (ii) the distribution fitting method. Two examples of small-angle X-ray/neutron scattering data analysis using VSAS are presented, and the fitting results are compared to the transmission electron microscope (TEM) observation.

Single crystals of CeAuGa₃ which crystallize in a BaAl₄-type structure are synthesized and their physical properties were investigated by magnetization, transport, and specific heat measurements. The BaAl₄-type CeAuGa₃ is a highly anisotropic ferromagnet with the transition temperature with $T_c=1.8\text{K}$, which is confirmed by the hysteresis loop at low temperatures in magnetization measurements. Crystalline-electric field plays an important role in magnetic properties and the small Sommerfeld coefficient $\gamma =12.6\text{mJ}/{\text{mol K}}^2$ indicates that CeAuGa₃ has a weak Kondo effect. These observations demonstrate that CeAuGa₃ is an interesting example involving the possible interplay of ferromagnetic, crystalline-electric field and Kondo effect.

The radiation effects of silicone rubber under different atmospheres are of great significance to evaluate the aging behavior of materials, and to assess their practical application life. The radiation-induced cross-linking and degradation of polydimethylsiloxane rubber were confirmed firstly by ¹H NMR and high-temperature GPC, respectively. By using the established gas collecting system and gaseous chromatography method, we systematically investigated the gaseous products of irradiated silicone rubber at different oxygen concentrations. With the increase of oxygen concentration, the yield of CH₄ decreases sharply, while the yield of hydrogen changes slightly. It can be further demonstrated that the reduction of CH₄ concentration in the irradiated silicone rubber system is mainly due to the inhibition of CH₄ formation, instead of the CH₄ degradation, indicating that oxygen directly influences the conversion process of methyl radicals. Similarly, by monitoring the oxygen consumption, it is proved that oxygen is directly involved in the degradation process of silicone rubber, and oxygen scavenged the methyl radicals, which supressed the conversion process of methyl radicals to CH₄. Finally, the radiation-induced crosslinking and degradation mechanism of raw silicone rubber was deduced by combining the gaseous products analysis and DFT calculation. It is demonstrated that the release of CH₄ can be used to assess the radiation effect of silicone rubber. This work provides a novel method to understand deeply the radiation-induced crosslinking and degradation mechanism of silicone rubber under different atmospheres.

The nuclear analysis has been of important significance in the field of nuclear science and technology. The developing trends and some frontier topic of nuclear analysis techniques as well as their applications have been presented in this paper. Four categories of nuclear analysis techniques have been mainly reviewed, which include radiochemical analysis, Z-pinch driven dynamic hohlraum for inertial confinement fusion, nuclear reactor analysis method and neutron scattering techniques. The future directions for them have been also summarized and viewed.

Despite extensive theoretical and experimental studies, there is still no universal picture for water dissociation on actinide dioxide surfaces. Based on ab initio molecular dynamics studies, we systematically investigated the influences of surface morphology and stoichiometry of the UO₂ (001) surface on the adsorption behavior of a water molecule. We find that the critical factor corresponding to water dissociation is the existence of surface actinide atoms. On the normal UO₂ (001) surface, surface U atoms are ready to bond with dissociated hydroxyl groups and the adsorbed water molecules dissociate spontaneously upon approaching. Comparatively, the surface U atoms on the oxygen-over surface are fully bonded with oxygen atoms, and the approaching water molecule do not dissociate. On a more realistic trench UO₂ surface, we find that approaching water molecules can steadily adsorb in the trench area after weakly bonding with two oxygen atoms in the trench. Our work reveals the vital role of surface actinide atoms in dissociating approaching water molecules, which is meaningful for macroscopic modellings of actinide corrosion.

In present study, the model Fe–9Cr alloy and two nanostructured ferritic alloys (NFAs) CNA1 and 9YWTV with high application potential in advanced nuclear power systems were selected to systematically investigate the effect of sink strength on helium bubble behavior at elevated temperatures. Helium bubble formation for a constant implanted He concentration of ∼7500 atomic parts per million (appm) was characterized using transmission electron microscopy (TEM) at 500 and 700 °C. A quantitative research and comparison of the influence for a specific sink strength on bubble formation was illustrated. Results showed that the introduction of nanoparticles into NFAs can effectively reduce bubble coarsening by sequestering the implanted helium into dispersed small bubbles due to the sufficient He entrapment by interfaces between the nanoprecipitates and the surrounding matrix. In addition, the NFAs with higher sink strength (9YWTV) revealed a higher suppression effects on bubble growth compared to general particle-free Fe–9Cr alloy and CNA1 with lower sink strength. This can be attributed to the comparable mean free path of He diffusion with the inter-particle distance for high particle density in 9YWTV. Meanwhile, the suppression effects of sinks on bubble growth decreased with increasing temperature from 500 to 700 °C. The sink strength of the order of 10¹⁵ m⁻² and 10¹⁶ m⁻² showed favorable suppression effect on bubble coarsening at 500 °C and 700 °C, respectively.