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J Hazard Mater ; 429: 128369, 2022 05 05.
Artigo em Inglês | MEDLINE | ID: mdl-35236039


To properly manage nuclear wastes is critical to sustainable utilization of nuclear power and environment health. Here, we show an innovative carbiding strategy for sustainable management of radioactive graphite through digestion of carbon in H2O2. The combined action of intermolecular oxidation of graphite by MoO3 and molybdenum carbiding demonstrates success in gasifying graphite and sequestrating uranium for a simulated uranium-contaminated graphite waste. The carbiding process plays a triple role: (1) converting graphite into atomic carbon digestible in H2O2, (2) generating oxalic ligands in the presence of H2O2 to favor U-precipitation, and (3) delivering oxalic ligands to coordinate to MoVI-oxo anionic species to improve sample batching capacity. We demonstrate > 99% of uranium to be sequestrated for the simulated waste with graphite matrix completely gasifying while no detectable U-migration occurred during operation. This method has further been extended to removal of surface carbon layers for graphite monolith and thus can be used to decontaminate monolithic graphite waste with emission of a minimal amount of secondary waste. We believe this work not only provides a sustainable approach to tackle the managing issue of heavily metal contaminated graphite waste, but also indicates a promising methodology toward surface decontamination for irradiated graphite in general.

Grafite , Resíduos Radioativos , Radioatividade , Urânio , Carbono , Digestão , Resíduos Perigosos , Peróxido de Hidrogênio , Molibdênio , Resíduos Radioativos/análise , Resíduos Radioativos/prevenção & controle
ACS Appl Mater Interfaces ; 12(34): 38106-38112, 2020 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-32799447


Platinum-based single-atom catalysts (SACs) are among the most promising candidates for the practical applications of electrochemical hydrogen evolution reaction (HER), but their catalytic efficiency remains to be further enhanced. Herein, a well-designed nanoarray-structured nitrogen-doped graphite foil (NNGF) substrate is introduced to support Pt SACs in Pt-N4 construction (Pt1/NNGF) for HER. Within NNGF, the constructed nanoarray-structured surficial layer for supporting Pt SACs could enhance the exposure of active sites to the electrolyte and improve the reaction and diffusion kinetics; meanwhile, the retained graphite structures in bulk NNGF provide not only the required electrical conductivity but also the mechanical stability and flexibility. Because of such double-layer structures of NNGF, stable Pt-N4 construction, and binder-free advantages, the Pt1/NNGF electrode exhibits a low overpotential of 0.023 V at 10 mA cm-2 and a small Tafel slope of 29.1 mV dec-1 as well as an excellent long-term durability.

Artigo em Chinês | MEDLINE | ID: mdl-25417307


OBJECTIVE: To explore the surgical indications, decompression and fusion method, and fusion level selection of degenerative lumbar scoliosis (DLS) and multi-segment lumbar spinal stenosis. METHODS: Between April 2000 and November 2011, 46 cases of DLS and multi-segment lumbar spinal stenosis were treated with multi-level decompression by fenestration and crept enlargement plus internal fixation by interbody and posterior-lateral bone graft fusion (5 segments or above). Of 46 cases, 25 were male and 21 were female, with a mean age of 70.2 years (range, 65-81 years) and with a mean disease duration of 6.4 years (range, 4 years and 6 months to 13 years). X-ray films showed that the lumbar Cobb angle was (26.7 ± 10.0) degrees, and the lumbar lordotic angle was (20.3 ± 8.8)degrees. The lumbar CT and MRI images showed three-segment stenosis in 24 cases, four-segment stenosis in 17 cases, and five-segment stenosis in 5 cases. A total of 165 stenosed segments included 12 L1,2, 34 L2,3, 43 L3,4, 45 L4,5, and 31 L5 and S1. Visual analogue scale (VAS) score, Oswestry disability index (ODI), and Japanese Orthopedic Association (JOA) score (29 points) were employed to evaluate effectiveness. RESULTS: Thirteen patients had leakage of cerebrospinal fluid during operation, and no infection was found after corresponding treatment; pulmonary infection and urinary system infection occurred in 4 and 2 patients respectively, who relieved after received antibiotic therapy; 8 patients with poor wound healing received dressing change, adequate drainage, debridement and suture. No death, paralysis, central nervous system infection, or other complication was observed in these patients. Forty-six cases were followed up 12-72 months (mean, 36.2 months). Lumbago and backache and intermittent claudication of lower extremity were obviously improved. During follow-up, no screw incising, loosening and broken screws, or pseudarthrosis was noted under X-ray film and CT scanning. At last follow-up, the lumbar Cobb angle was reduced to (9.8 ± 3.6) degrees, while the lumbar lordotic angle was increased to (34.1 ± 9.4) degrees, which were significantly improved when compared with preoperative ones (t = 16.935, P = 0.000; t = 15.233, P = 0.000). At last follow-up, VAS, ODI, and JOA scores were 3.2 ± 1.2, 35.5% ± 14.0%, and 26.6 ± 5.7 respectively, showing significant differences when compared with preoperative scores (8.0 ± 2.2, 60.8% ± 13.3%, and 12.9 ± 3.4) (t = 19.857, P = 0.000; t = 16.642, P = 0.000; t = 15.922, P = 0.000). CONCLUSION: Multi-segment decompression by fenestration and crept enlargement plus internal fixation by interbody and posterior-lateral bone graft fusion is helpful to relieve nerve compression symptoms, rebuild spinal balance, and improve the life quality of the patients. It is a very effective way to treat DLS and multi-segment lumbar spinal stenosis.

Descompressão Cirúrgica , Vértebras Lombares/cirurgia , Escoliose/cirurgia , Fusão Vertebral , Estenose Espinal/cirurgia , Idoso , Idoso de 80 Anos ou mais , Dor nas Costas , Parafusos Ósseos , Transplante Ósseo , Feminino , Seguimentos , Fixação Interna de Fraturas , Humanos , Dor Lombar , Região Lombossacral , Imageamento por Ressonância Magnética , Masculino , Complicações Pós-Operatórias , Resultado do Tratamento