Journal of Radioanalytical and Nuclear Chemistry最新文献

This paper provides insights into the radioactivity levels in soils and marine sediments from selected monitoring sites in Singapore. The environmental samples were measured for naturally occurring (e.g., ⁴⁰K, ²³⁸U, ²³⁵U, ²³⁴U and ²³²Th) and anthropogenic (e.g., ⁹⁰Sr, ¹³⁷Cs, ²³⁹Pu and ²⁴⁰Pu) radionuclides. Additionally, the ¹³⁷Cs activity in surface seawater was analysed. In soil, the decay series of ²³²Th and ²³⁸U are the highest contributors to the total radioactivity, while in sediments, ⁴⁰K is the main contributor to the total radioactivity. The massic activities of anthropogenic radionuclides in soil (⁹⁰Sr: 0.24–0.34 Bq kg⁻¹; ¹³⁷Cs: < 0.3–0.65 Bq kg⁻¹; ^239+240Pu: 0.002–0.057 Bq kg⁻¹) and sediment (⁹⁰Sr: 0.15–0.17 Bq kg⁻¹; ¹³⁷Cs: < 0.46–0.54 Bq kg⁻¹; ^239+240Pu: 0.239–0.294 Bq kg⁻¹), and the activity concentration of ¹³⁷Cs in seawater (¹³⁷Cs: 1.1 mBq kg⁻¹), are low and comparable to the values reported for the region. The Pu isotope data demonstrates that the main source of anthropogenic radionuclides in soil (²⁴⁰Pu/²³⁹Pu atom ratios: 0.17–0.19) is the global fallout from nuclear weapons testings (NWTs); in sediments (²⁴⁰Pu/²³⁹Pu atom ratios: 0.24–0.26), contributions from the Pacific Proving Grounds (PPG) have also been identified. This study also highlights significant differences in radioactivity levels in soils between the northern and central regions of Singapore, which are attributed to soil disturbances in the northern region as a result of intensive anthropogenic activities carried out in the 1980s.

This study demonstrates the construction and operation of a portable, solid-state thermal neutron sensor that utilizes a photodiode coated with a thin layer of boron-10 (¹⁰B). The boron layer was created using pulsed laser deposition and analyzed with neutron depth profiling (NDP) and scanning electron microscopy (SEM). The sensor's response to both thermal and cold neutrons was evaluated under varying neutron fluence rates. Additionally, the impact of the angles between the neutron beam and the sensor surface was examined. SEM results showed a porous ¹⁰B film structure, while NDP indicated a nearly uniform distribution of the isotope throughout the film. The electronic signal generated by the sensor exhibited a linear response to neutron fluence rates. However, the measured intrinsic efficiencies were lower than those of commercially available gas-phase detectors, with thermal neutrons yielding an efficiency of (1.17 ± 0.01) % and cold neutrons at (1.78 ± 0.01) %. Potential design upgrades that could increase the sensor's efficiency in the future are also discussed.

^99mTc, as the most widely used radioactive nuclide in diagnostic imaging, whose supply heavily relies on the ⁹⁹Mo. Neutron activation technology, as an alternative to uranium fission technique, has become a pivotal route for producing ⁹⁹Mo. A critical aspect of its practical application lies in enhancing the sorption capacity of the column chromatography packing materials for the low specific activity molybdenum product. This study synthesizes two types of iron-cerium bimetallic composite materials, iron-cerium alkoxide (ICA) and iron-cerium oxide (ICO), as novel column chromatography packing materials compatible with low specific activity ⁹⁹Mo. Characterization techniques such as TEM, XRD, and BET were employed to reveal the surface morphology and mesoporous structure of ICA and ICO. An evaluation of their sorption performance showed that both ICA and ICO exhibited rapid sorption kinetics (< 10 min) and excellent sorption selectivity. Notably, ICA demonstrated a static sorption capacity of 207 mg Mo/g and a dynamic sorption capacity of 180 mg Mo/g, surpassing most reported adsorbents. Mechanistic studies using XPS, FT-IR, and zeta potential measurement suggest that the sorption of Mo onto both ICA and ICO is primarily governed by electrostatic interactions. Additionally, the sorption mechanism for ICA also includes ion exchange and surface complexation. With Re being the most common non-radioactive substitute for ^99mTc, desorption separation experiments revealed that ICA has a Re elution rate of over 75%, confirming its potential as a promising candidate material in low specific activity ⁹⁹Mo/^99mTc generators.

Using a high-purity germanium detector (HPGe), the natural and artificial radioactivity in soil samples taken from agricultural regions near the Al-Kasak oil refinery were examined. According to estimates, the average specific activities of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs were 20, 15, 283, and 3.6 Bq kg⁻¹, respectively. The specific activities of ²²⁶Ra, ²³²Th, ⁴⁰K, and ¹³⁷Cs in the soil samples were comparatively lower than the average values of these radionuclides worldwide. The investigation also analyzed several radiological hazard indices. The hazard indices calculated in this study were utilized to assess the potential health risks associated with radiation in the soil. The results indicate that these indices are significantly below their permissible limits. Therefore, the soil in the study area does not pose any excessive radiation exposure to the inhabitants and can be safely used as construction material without presenting an immediate radiological threat to the public.

A practical approach has been developed to estimate the thermal neutron self-shielding correction of Egyptian monazite sand, a primary source of rare earth elements (REEs), thorium (Th) and phosphorus (P) with uranium (U) quantity, consequently, the k₀ Neutron Activation analysis (k₀-NAA) method can be used to accurately quantify the elemental content. Assessment of neutron self-shielding correction was based on the optimization of the mass-specific count rate mathematical relationship by practical treatments including the using of inert diluting substance namely silicon dioxide (SiO₂). It demonstrated that neutron self-shielding underestimated the elements' concentration in the sample by 59.2%. k₀-NAA method detected REEs at 56.48%, Th at 5.67%, U at 0.381%. The approach was evaluated using synthetic monazite and also compared with ICP-MS and theoretical calculations. The overall performance of the method proved to be acceptable.

This study used oxidative pre-treatment and leaching methods to examine the extraction efficiency of uranium oxide (UO₂) from UO₂ ore. A 4-hour oxidative pre-treatment at 75 °C using a solution of 0.1 g of KMnO₄, 3 mL of NaClO, and 12 mL of water at pH 0.3 was one of the ideal settings. After this treatment, 100 mL of deionized water at room temperature showed a leaching rate of 99.9% after 24 h. The results showed that leaching efficiency was much increased by acidic conditions. These findings providing insights to improve extraction in the uranium industry.

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Radiosynovectomy is a treatment for patients with rheumatoid arthritis (RA) that affects joints by injecting beta-emitting radiopharmaceuticals into the synovial membrane of inflamed joints. In this study, we established ³²Phosphorus labelled hydroxyapatite (³²P-HAp) using gamma-irradiated hydroxyapatite material from bovine. Our results showed that gamma-irradiation of bovine HAp tends to agglomerate the particle and form a micro-sized HAp. In addition, irradiated HAp exhibited Ca/P ratio higher than non-irradiated HAp. The ex-vivo biodistribution studies exhibited a high accumulation of irradiated ³²P-HAp in the inflamed joints, resulting in good therapeutic effectiveness. Our study demonstrated the potential of ³²P-HAp from irradiated bovine hydroxyapatite for radiosynovectomy therapy.

In the present paper, the health risks to astronauts due to space radiation exposure and the excess cancer risk (ECR) caused by high-level natural radiation exposure area residents were estimated manes on the National Aeronautics and Space Administration (NASA) Space Cancer Risk (NSCR)-2012 model and RESRAD code, respectively. The total risk of exposure-induced cancer (REIC) and total risk of exposure-induced death (REID) were calculated for different ages and genders. In contrast, the mortality and morbidity due to High Natural Background Radiation Exposure areas (HNBRAs) were simulated for different genders and ages. The results showed that the morbidity of the HNBRAs area for males and females was less than the REIC value of the 6-month mission at the International Space Station (ISS). Also, the results indicated that the mortality of the HNBRAs area was equal to the REIC 6-month mission for males. The mortality rate in the HNBRA area was higher than the average rate for females in the REIC 6-month mission.

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This study reveals the transformation of the Super Uranyl-binding Protein (SUP) gene with high uranium selectivity and binding affinity into Deinococcus Radiodurans, a genetically modified bacterium with high uranium adsorption capacity and resistance to radiation. The optimal adsorption conditions and mechanism of Deino-SUP for uranium under different environmental conditions were investigated. The results demonstrated the successful construction of Deino-SUP, a recombinant strain with excellent uranium adsorption capacity and radiation resistance. The adsorption of uranium by Deino-SUP is mainly controlled by chemisorption, and the adsorption rate of uranium by Deino-SUP is better than that by Deino-wt.

The technique of adsorption is commonly employed to capture volatile radionuclides, finding extensive use in various fields, including gas treatment in nuclear power plants, protection of personnel, and capture systems for medical radioactive isotopes. An adequate mathematical description is essential for the design, calculation, and prediction of the output concentration and distribution of radionuclides in the sorbent bed over time. The theory of chromatography for non-radioactive adsorptives can now be considered detailed. However, its applications for radioactive gases are not as numerous and are generally limited to the simplest cases (stationary adsorption mode, linear isotherm). The present investigation improves upon the current model of the equilibrium adsorption layer by incorporating the radioactive decay of the adsorptive. At any given time, the complete description of the radionuclide distribution in the mobile and solid phase can be obtained through the resulting equation system, regardless of the type of adsorption isotherm. Simple analytical solutions were also obtained for the most practical case of linear adsorption isotherm. The frontal adsorption of the short-lived isotope ²²⁰Rn on activated AG-3 at 30 °C was studied in the air flow rate from 1 to 8 l/min (superficial linear air velocity from 50 to 430 cm/min). The experimental results were fully corresponded to the theoretical representations described in the paper.