a b s t r a c tAlthough China's nuclear power industry is relatively young and the management of its spent nuclear fuel is not yet a concern, China's commitment to nuclear energy and its rapid pace of development require detailed analyses of its future spent fuel management policies. The purpose of this study is to provide an overview of China's fuel cycle program and its reprocessing policy, and to suggest strategies for managing its future fuel cycle program. The study is broken into four sections. The first reviews China's current nuclear fuel cycle program and facilities. The second discusses China's current spent fuel management methods and the storage capability of China's 13 operational nuclear power plants. The third estimates China's total accumulated spent fuel, its required spent fuel storage from present day until 2035, when China expects its first commercialized fast neutron reactors to be operational, and its likely demand for uranium resources. The fourth examines several spent fuel management scenarios for the present period up until 2035; the financial cost and proliferation risk of each scenario is evaluated. The study concludes that China can and should maintain a reprocessing operation to meet its R&D activities before its fast reactor program is further developed.
SUMMARYThe rapid expansion of nuclear energy in China has intensified concerns regarding spent fuel management. However, the consequences of failure or delay in developing approaches to managing spent fuel in China have not yet been explicitly analyzed. Thus, a dynamic analysis of transitions in nuclear fuel cycles in China to 2050 was conducted. This multidisciplinary study compares the environmental, security, and economic consequences of choices among ongoing technology development options for spent fuel management. Four transition scenarios were identified: the direct disposal of PWR (Pressurized Water Reactor) spent fuel, the recycling of PWR spent fuel through PWR-MOX (Mixed Oxides), the PWR-MOX followed by fast reactors, and the recycling of PWR spent fuel using fast reactors. Direct disposal would have the lowest cost of electricity generation under the current market conditions, while the reprocessing and recycling of PWR spent fuel would benefit the Chinese nuclear power program by reducing the generation of high level waste (67-82%), saving natural U resources (9-17%), and reducing Pu management risk (24-58%). Moreover, a fast reactor system would provide better performance than one-time recycling through PWR-MOX. The latter also poses high risks in managing the build-up of separated Pu.
Context: Bergenin, isolated from the herb of Bergenia purpurascens (Hook. f. et Thoms.) Engl., has anti-inflammatory, antitussive, and wound healing activities. However, whether bergenin affects the activity of human liver cytochrome P450 (CYP) enzymes remains unclear.Materials and methods: In this study, the inhibitory effects of bergenin (100 μM) on the eight human liver CYP isoforms (i.e., 1A2, 3A4, 2A6, 2E1, 2D6, 2C9, 2C19 and 2C8) were investigated, enzyme kinetics and time-dependent inhibition studies were also performed in vitro using human liver microsomes (HLMs).Results: The results showed that bergenin inhibited the activity of CYP3A4, 2E1 and 2C9, with IC50 values of 14.39, 22.83 and 15.11 μM, respectively, but other CYP isoforms were not affected. Enzyme kinetic studies showed that bergenin was not only a non-competitive inhibitor of CYP3A4, but also a competitive inhibitor of CYP2E1 and 2C9, with Ki values of 7.71, 11.39 and 8.89 μM, respectively. In addition, bergenin is a time-dependent inhibitor for CYP3A4 with Kinact/KI value of 0.025/3.50 μM−1 min−1.Discussion and conclusions: The in vitro studies of bergenin with CYP isoforms indicate that bergenin has the potential to cause pharmacokinetic drug interactions with other co-administered drugs metabolized by CYP3A4, 2E1 and 2C9. Further clinical studies are needed to evaluate the significance of this interaction.
1. The oral bioavailability of puerarin is poor which hindered its clinical performance. 2. This study investigates the effects of verapamil on the pharmacokinetics of puerarin in rats. 3. The pharmacokinetics of orally administered puerarin (50 mg/kg) with or without verapamil pretreatment (10 mg/kg/day for 7 days) were investigated. The plasma concentration of puerarin was determined using LC-MS/MS method, and the pharmacokinetics profiles were calculated and compared. Caco-2 cell transwell model was also used to investigate the effects of verapamil on the transport pf puerarin. 4. The results showed that when the rats were pretreated with verapamil, the maximum concentration (C) of puerarin increased from 683.7 ± 51.2 to 933.5 ± 75.8 ng/mL (P < 0.05), and the area under the concentration-time curve from zero to infinity (AUC) also increased from 3687.3 ± 444.6 to 5006.1 ± 658.6 μg·h/L (P < 0.05). The Caco-2 cell transwell experiments indicated that verapamil could decrease the efflux ratio of puerarin from 1.90 to 1.19 through inhibiting the activity of P-gp. 5. In conclusion, these results indicated that verapamil could affect the pharmacokinetics of puerarin, possibly by increasing the systemic exposure of puerarin by inhibiting the activity of P-gp.
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