[en] A process for treating low radioactive uranium wastewater by ultrasonic combined flocculation and precipitation has been developed and optimized. By using arsenazo III spectrophotometry to detect the mass concentration of uranium ions, the optimal coupling mode of ultrasonic flocculation and the optimal values of pH value, flocculant dosage, and ultrasonic power were obtained through single factor experiments. The conclusion drawn is that the optimal coupling method is to first add flocculants, then treat the solution with ultrasound, and finally stir the solution. The optimal values for each single factor are: the initial pH value of the solution is 9, the dosage of flocculant is 80 mg/L, and the sound energy density is 0.36 W/ml.The Box Behnken response surface experiment was designed using Design-Expert software. After completing the response surface experiment, a regression model for uranium ion removal rate was obtained. The highest uranium ion removal rate under theoretical conditions was obtained by solving the model.The predicted values of uranium ions removal rate of 95.68% was obtained with an acoustic energy density of 0.436 W/ml and a flocculant dosage of 88 mg/L at pH 9.It was observed that the actual experimental data under the same conditions are 95.41% The order of the influence factors of each process parameter on the uranium ion removal rate is: pH > flocculant dosage > ultrasonic power. Among them, there was a significant interaction between ultrasonic power and flocculant dosage. (author)

[en] To accurately measure and evaluate the radiation dose of ²²⁰Rn and its progeny, a ²²⁰Rn chamber with an airflow model has been developed and studied, but it is difficult to take into consideration many relevant factors such as adsorption, wall attachment, and decay. This paper proposes the concept of cyclic loss rate of ²²⁰Rn progeny based on progeny supplement technology, establishes a theoretical formula to calculate the cyclic loss rate, and analyzes the relationship between cyclic loss rate, fan frequency, and aerosol particle size through both experiments and modelling methods. The feasibility of the cyclic loss rate model is experimentally verified. (author)

[en] Objective: To evaluate the contrast-enhanced CT value in the diagnosis of giant cell tumor. Methods: From 2461 bone tumors and tumor-like lesions with contrast enhanced CT, 408 osteolytic lesions were selected and analyzed retrospectively. Three ROI were selected for every lesion, then the average post-contrast CT value and average △ΔCT value of every lesion were calculated by two observers independently. Thirty lesions which were randomly selected from the 408 lesions were measured by two doctors to assess the overall precision of measurements. Contrast agents Iohexol (350 mg I/ml), Iopromide (370 mg I/nl) and Iobitridol (350 mg I/ml) were recorded in 148 GCT and 408 osteolytic lesions. The two observed values were analyzed respectively by using the One-way ANOVA. The 408 lesions were divided into giant cell tumor (GCT) and non-giant cell tumor (non-GCT) according to pathological results, and ROC curve analysis was carried out to get the cutoff values for the diagnosis of GCT and their sensitivity, specificity were determined. Results: There was no significant difference of the average post contrast CT values between two observers (t = 0.178, P > 0.05), nor the average ΔCT values (t = 0.682, P > 0.05), and the overall precision was 11.94%. There was no significant difference amongst the three groups average post contrast CT values (126.41 ± 27.13), (128.90 ± 23.12), (127.61 ± 23.02) HU for the 142 giant cell tumors (F = 0.10, P > 0.05), nor the average ΔCT values (82.72 ± 24.83), (81.94 ± 21.71), (84.06 ± 19.45) HU (F = 0.05, P > 0.05). There was no significant difference amongst the three groups average post contrast CT values (99.15 ± 36.44), (107.08 ± 39.28), (105.75 ± 31.17) HU for the 408 lesions (F = 1.905, P > 0.05), nor the average ΔCT values (58.63 ± 33.23), (64.40 ± 36.38), (63.04 ± 28.50) HU (F = 1.149, P > 0.05). The average post contrast CT values of GCT and non-GCT were (127.05 ± 25.69) and (88.07 ± 34.08) HU respectively; The average ΔCT values of GCT and non-GCT were (82.78 ± 23.38) and (48.43 ± 31.68) HU respectively. If average post contrast CT value ≥ 96.5 HU was used as cutoff value, the sensitivity and specificity for the diagnosis of GCT were 89.44% and 62.41% respectively. If average ΔCT value ≥ 41.5 HU was chosen, then the sensitivity and specificity were 98.59% and 48.12% respectively. Conclusion: The cutoff values were ≥ 96.5 HU for average post contrast CT value and ≥ 41.5 HU for average ΔCT value in the diagnosis of GCT, which both had high sensitivity and low specificity, and average ΔCT value < 41.5 HU was helpful to exclude the diagnosis of GCT. (authors)

[en] Measuring the conductivity changes of sensing materials to detect a wide range of radiation energy and dosage is one of the major sensing mechanisms of radiation sensors. Carbon nanotube (CNT) filled composites are suitable for sensing radiation because of the extraordinary electrical properties of CNTs and the CNT-network formed inside the polymer matrix. Although the use of CNT-based nanocomposites as potential radiation sensing materials has been widely studied, there is still a lack of theoretical models to analyze the relationship between electrical conductivity and radiation dosages. In this article, we propose a 3D model to describe the electrical conductivity of CNT-based nanocomposites when being irradiated by ionizing radiation. The Monte Carlo method has been employed to calculate radiation intensity, CNT concentration and alignment’s influence on the electrical conductivity. Our simulation shows a better agreement when CNT loading is between the percolation threshold and 3% volume fraction. Radiation experiments have been performed to verify the reliability of our model to illustrate a power function relationship between the electrical conductivity of a CNT-filled polymer and radiation intensity. In addition, the predicted alignment to obtain the best sensitivity for radiation sensing has been discussed to help with CNT-network building in the fabrication process. (paper)

[en] Perovskite CaTiO₃:Yb³⁺,Er³⁺ nanocubes with tunable upconversion luminescence (UCL) were prepared by a solvothermal method. The structure and morphology of the final product after being sintered at 700 °C for 2 h were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The upconversion emissions of CaTiO₃:Yb³⁺,Er³⁺ under the excitation of 980 nm diodes laser consist of two typical emission bands from ⁴F_9/2 → ⁴I_15/2 and ⁴S_3/2, ²H_11/2 → ⁴I_15/2 transitions. The UCL properties depending on the doping contents of Yb³⁺ to Er³⁺ were investigated in detail. The maximum R/G ratio was observed at Yb³⁺ concentration of 15 mol%. The multiphotonic upconversion mechanism of controllable red-to-green ratio in CaTiO₃:Yb³⁺,Er³⁺ nanocubes was addressed based on both steady state and transient spectroscopy data.