通讯机构：
[Feng, Zhi-Gang] U;Univ South China, Sch Nucl Resource Engn, Hengyang 421001, Peoples R China.
摘要：
Five soil profiles were sampled around a uranium waste rock dump in South China, which included two unpolluted and three potentially uranium-polluted profiles. Through the comparison of the uranium distribution characteristics and the analysis of the uranium chemical forms of these profiles, the following conclusions can be drawn: (1) significant uranium pollution to the surrounding soils was caused by the dump, and the average uranium in these soils, such as the profiles WP1, WP2 and WP3, was 633.6, 9 and 2.7 times more enriched than the background value; (2) the exotic uranium, which was preferentially aggregated in the upper layer of the soils near the pollution source, would be gradually precipitated in the lower layer of the soils away from the pollution source; (3) the input flux of the exotic uranium of each chemical form would be larger in the soils closer to the pollution source.
摘要：
The anaerobic microcosms amended with 30 mM bicarbonate and without bicarbonate were established, respectively, and the reduction of U(VI) in the microcosms by functionalized indigenous microbial communities was investigated. Results of the chemical extraction and XANES analysis showed that the proportions of U(IV) in the microcosms amended with bicarbonate were 10 % lower than without bicarbonate at day 46. The amount of Cellulomonadaceae, Desulfovibrionaceae, Peptococcaceae and Veillonellaceae amended with bicarbonate was lower than without bicarbonate, so the reduction of U(VI) was less. The experimental results show that the high concentration bicarbonate has a significantly inhibitory effect on the reduction of U(VI).
摘要：
To investigate the relationship between nonlinear parameters and spontaneous combustion tendency of sulfide ores, nine different sulfide ore samples were taken from a pyrite mine in China, and induced spontaneous combustion experiment was carried out in the laboratory. Different stages of the induced spontaneous combustion process were studied by integrating wavelet technology and nonlinear dynamics theory. The results show that ignition points of all the ore samples are above 330 ~°C, indicating that sulfide ores of the pyrite mine are difficult to combust spontaneously under normal mining conditions. Spontaneous combustion process includes three stages: incubation stage, development stage and approaching stage. The average temperature rising rate of the three stages are 1.0~oC/min,2.0~oC/min and 4.2~oC/min, respectively. During the spontaneous combustion process, mean values of approximate entropy and correlation dimension increase at first, and then decrease in the following stage. The mean value of the maximum Lyapunov exponent increases with the passage of reaction time. In a whole, correlation among the three nonlinear parameters firstly weakens, then enhances, and the best correlation period is at approaching stage. As ignition point increases, the maximum Lyapunov exponent of approaching stage decreases. Therefore, combustible tendency of sulfide ores could be qualitatively evaluated based on the maximum Lyapunov exponent of this stage.
摘要：
A new method, named relocation, was proposed to reduce the impact of sensor errors systematically, especially when available data of sensors are abundant. The procedure includes evaluating the reliability of every sensors datum, processing the initial location by the credible data, and selecting a set of equations with optimal noise tolerance according to the relative relationship between the initial location and sensors location, then calculating the final location by k-mean voting. The results obtained in this research include comparing traditional location method with the presented method in both simulation and field experiment. In the field experiment, the location error of relocation method reduced 41.8% compared with traditional location method. The results suggested that relocation method can improve the fault-tolerant performance significantly.
摘要：
This study aimed to evaluate the biological effects of gamma irradiation on zebrafish embryos. Different doses of gamma rays (0.01, 0.05, 0.1, 0.5 and 1 Gy) were used to irradiate zebrafish embryos at three developmental stages (stage 1, 6 h post-fertilization (hpf); stage 2, 12 hpf; stage three, 24 hpf), respectively. The survival, malformation and hatching rates of the zebrafish embryos were measured at the morphological endpoint of 96 hpf. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx) and glutathione S-transferase (GST) were assayed. Morphology analysis showed that gamma irradiation inhibited hatching and induced developmental toxicity in a dose-dependent manner. Interestingly, after irradiation the malformation rate changed not only in a dose-dependent manner but also in a developmental stage-dependent manner, indicating that the zebrafish embryos at stage 1 were more sensitive to gamma rays than those at other stages. Biochemical analysis showed that gamma irradiation modulated the activities of antioxidant enzymes in a dose-dependent manner. A linear relationship was found between GPx activity and irradiation dose in 0.1–1 Gy group, and GPx was a suitable biomarker for gamma irradiation in the dose range from 0.1 to 1 Gy. Furthermore, the activities of SOD, CAT, GR and GPx of the zebrafish embryos at stage 3 were found to be much higher than those at other stages, indicating that the zebrafish embryos at stage 3 had a greater ability to protect against gamma rays than those at other stages, and thus the activities of antioxidant enzymes changed in a developmental stage-dependent manner.
摘要：
Acidophilic microorganisms involved in uranium bioleaching are usually suppressed by dissolved fluoride ions, eventually leading to reduced leaching efficiency. However, little is known about the regulation mechanisms of microbial resistance to fluoride. In this study, the resistance of Acidithiobacillus ferrooxidans ATCC 23270 to fluoride was investigated by detecting bacterial growth fluctuations and ferrous or sulfur oxidation. To explore the regulation mechanism, a whole genome microarray was used to profile the genome-wide expression. The fluoride tolerance of A. ferrooxidans cultured in the presence of FeSO4 was better than that cultured with the S0 substrate. The differentially expressed gene categories closely related to fluoride tolerance included those involved in energy metabolism, cellular processes, protein synthesis, transport, the cell envelope, and binding proteins. This study highlights that the cellular ferrous oxidation ability was enhanced at the lower fluoride concentrations. An overview of the cellular regulation mechanisms of extremophiles to fluoride resistance is discussed.
摘要：
A kind of functional plant composite adsorbent was prepared through diethylenetriamine modifing the Cycas revoluta leaves for low concentration of U(VI) in waste water. The dynamic behavior of the adsorption, the Langmuir and Freundlich equations and the thermodynamic parameters was were also examined in the present study. The experimental results showed that diethylenetriamine functionalized Cycas revoluta leaves used for low concentration of uranium possessed many advantages such as widely raw material sources, simple and economy for preparation, less adsorbent dosage, short balance time, high adsorption efficiency, good chemical and mechanical stability, and can be effective regeneration or reused.
摘要：
Tailings from mining and milling of uranium ores potentially are large volumes of low-level radioactive materials. A typical environmental problem associated with uranium tailings is radon exhalation, which can significantly pose risks to environment and human health. In order to reduce these risks, it is essential to study the dynamical nature and underlying mechanism of radon exhalation from uranium mill tailings. This motivates the conduction of this study, which is based on the fractal and chaotic methods (e.g. calculating the Hurst exponent, Lyapunov exponent and correlation dimension) and laboratory experiments of the radon exhalation rates. The experimental results show that the radon exhalation rate from uranium mill tailings is highly oscillated. In addition, the nonlinear analyses of the time series of radon exhalation rate demonstrate the following points: (1) the value of Hurst exponent much larger than 0.5 indicates non-random behavior of the radon time series; (2) the positive Lyapunov exponent and non-integer correlation dimension of the time series imply that the radon exhalation from uranium tailings is a chaotic dynamical process; (3) the required minimum number of variables should be five to describe the time evolution of radon exhalation. Therefore, it can be concluded that the internal factors, including heterogeneous distribution of radium, and randomness of radium decay, as well as the fractal characteristics of the tailings, can result in the chaotic evolution of radon exhalation from the tailings.
作者机构：
[Zheng, Jifang; Yuan, Yan; Zhao, Tingting] Univ South China, Sch Pharmaceut & Biol Sci, Inst Biol, Changsheng West Rd 28, Hengyang City, Hunan, Peoples R China.;[Tang, Xiaoqing] Univ South China, Coll Med, Inst Neurosci, Changsheng West Rd 28, Hengyang City, Hunan, Peoples R China.;[Hu, Nan] Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium Mi, Changsheng West Rd 28, Hengyang City, Hunan, Peoples R China.
通讯机构：
[Zheng, Jifang] U;Univ South China, Sch Pharmaceut & Biol Sci, Inst Biol, Changsheng West Rd 28, Hengyang City, Hunan, Peoples R China.
摘要：
The mechanism of uranium-induced kidney cell cytotoxicity is not fully understood. Nrf2 is a transcription factor which can regulate gene expression of cystathionine β-synthase (CBS) and cystathionine γ-lyase (CSE) which are responsible for endogenous H2S formation. H2S is recognized as the gaseous mediator that exerts antioxidative and cytoprotective effects. Here, we assessed the in vitro effects of uranyl acetate on Nrf2 gene expression and endogenous H2S production in a stable rat kidney cell line (NRK-52E). The results imply that uranium treatment decreased cell viability and increased LDH release, indicating uranium-induced cytotoxicity. Uranium intoxication increased intracellular ROS and MDA contents, depleted GSH levels, and impaired SOD and CAT activities, which resulted in oxidative stress injuries. Uranium intoxication reduced CBS and CSE gene expression and endogenous H2S production. Uranium contamination decreased Nrf2 protein expression and nuclear translocation. RNA silencing of Nrf2 gene expression in kidney cells which had not been treated by uranium decreased CBS and CSE gene expression and endogenous H2S generation, which mirrored the effects of uranium exposure. In contrast, treating uranium-exposed kidney cells with Nrf2 activator (sulforaphane) preserved the protein levels of Nrf2, CBS and CSE, and endogenous H2S formation. Administration of NaHS (an H2S donor) to uranium-intoxicated kidney cells reduced cell damage and alleviated oxidative stress. These data imply that uranium-induced kidney cell cytotoxicity is mediated by decreased endogenous H2S production due to the down-regulation of CBS and CSE gene expression and reduced Nrf2 levels. Supplementary H2S generation and/or Nrf2 activation can mitigate the adverse effects of uranium on kidney cells.
The mechanism of uranium-induced kidney cell cytotoxicity is not fully understood.
摘要：
In this study, a one-dimensional steady-state mathematical model of radon transport in fragmented uranium ore was established according to Fick's law and radon transfer theory in an air-water interface. The model was utilized to obtain an analytical solution for radon concentration in the air-water, two-phase system under steady state conditions, as well as a corresponding radon exhalation rate calculation formula. We also designed a one-dimensional experimental apparatus for simulating radon diffusion migration in the uranium ore with various water levels to verify the mathematical model. The predicted results were in close agreement with the measured results, suggesting that the proposed model can be readily used to determine radon concentrations and exhalation rates in fragmented uranium ore with varying water levels.
摘要：
Anthraquinone-2-sulfonate (AQS) was employed in humus substitutes to evaluate the effects and influencing factors of U(VI) reduction-by Shewanella oneidensis MR-1 (S. oneidensis MR-1) under anaerobic-condition. The removal rate of U(VI) at 30 ℃ reaches 99.0% afterd 96 h with the pH value of 7.0 and AQS concentration of 1.0 mmol/L. The effective concentrations of AQS as the accelerator for U(VI) bioreduction are approximately 0.5-1.0 mmol/L. The bioreduction of U(VI) is inhibited when the concentration of AQS exceeds 2.0 mmol/L. The coexistence of ions, such as Cu~(2+), Cr~(6+), Mn~(2+), shows a remarkable negative effect on the U(VI) reduction, and Zn~(2+) shows less influence on the process compared with other tested ions. The U(VI) reduction is remarkably inhibited when the concentration of nitrate ion exceeds 1.0-mmol/L. Otherwise, no difference is found when the nitrate ion concentration is less than 0.5 mmol/L. Sulfate ion (<5.0 mmol/L) slightly promotes the U(VI) reduction. Zero-valent iron (ZVI) promotes the U(VI) reduction by S. oneidensis, and the reduction rate improves with increasing the amount of ZVI in the range of 0-2.0 g/L. The XPS result indicates that uranium deposits on the cell surface are in U(VI) and U(IV) forms, and the majority of uranium in the solution is stable UO_2.
摘要：
To verifying the feasibility of uranium recovery with fungal metabolic products in large-scale applications, column leaching and ion exchange of uranium was carried out. The uranium recovery reached 81.76 % in 14 days. The ion exchange curve for the leach solution obtained with the metabolic products of Aspergillus niger was in the shape of a wave. The elution curve was similar to that of leaching with H2SO4. The results indicate that leaching with the metabolic products of A. niger is a promising and environmentally friendly method for exploitation of low grade uranium ores in large-scale applications.
作者：
Feng, Z. G.*;Zhang, B.;Duan, X. Z.;Chen, R.;Wang, X. L.;...
期刊：
Journal of Residuals Science & Technology,2015年12(SUPPL-1):S159-S163 ISSN：1544-8053
通讯作者：
Feng, Z. G.
作者机构：
[Ma, Q.; Han, S. L.; Zhang, B.; Duan, X. Z.; Chen, R.; Feng, Z. G.; Wang, X. L.] Univ South China, Sch Nucl Resource Engn, Hengyang 421001, Peoples R China.;[Zhang, B.; Chen, R.; Wang, X. L.] Univ South China, Key Discipline Lab Natl Def Biotechnol Uranium &, Hengyang 421001, Peoples R China.
通讯机构：
[Feng, Z. G.] U;Univ South China, Sch Nucl Resource Engn, Hengyang 421001, Peoples R China.
摘要：
Six uranium tailings samples from the shallow depth of two large-scale uranium tailings ponds in South China, which were affected by pedogenesis, were analyzed to determine the occurrence modes of uranium. The results demonstrated that an average of nearly 80% of the uranium in the samples was mobile and potentially mobile, indicating that this type of uranium tailings could significantly threaten their ambient environment when their contents of uranium were relatively high. In this sense, the possibility of the in-situ immobilization of active uranium in the uranium tailings was discussed. The experimental data indicated that the active uranium could be immobilized through its reaction with phosphate, which was theoretically feasible and promising in curbing uranium pollution.
