RESUMO
The development of low-cost and long-lasting all-climate cathode materials for the sodium ion battery has been one of the key issues for the success of large-scale energy storage. One option is the utilization of earth-abundant elements such as iron. Here, we synthesize a NASICON-type tuneable Na4Fe3(PO4)2(P2O7)/C nanocomposite which shows both excellent rate performance and outstanding cycling stability over more than 4400 cycles. Its air stability and all-climate properties are investigated, and its potential as the sodium host in full cells has been studied. A remarkably low volume change of 4.0% is observed. Its high sodium diffusion coefficient has been measured and analysed via first-principles calculations, and its three-dimensional sodium ion diffusion pathways are identified. Our results indicate that this low-cost and environmentally friendly Na4Fe3(PO4)2(P2O7)/C nanocomposite could be a competitive candidate material for sodium ion batteries.
RESUMO
BACKGROUND: The differential diagnosis of severe acute respiratory syndrome (SARS) in patients with cancer can be challenging. Although diagnostic criteria for SARS have been issued by the World Health Organization (WHO), simple adoption of the established criteria may lead to overdiagnosis in patients with cancer or to an increase in the risk of spreading SARS within cancer hospitals. METHODS: The authors report their experience with the exclusion and quarantine of patients with cancer during the peak of the SARS epidemic in Beijing, China. The patients included 4 males and 7 females with a median age of 66 years (range, 39-73 years). RESULTS: All 11 patients met the WHO diagnostic criteria for probable SARS. Among those 11 patients with probable SARS, only 1 had confirmed SARS; for the other 10 patients, the possibility of SARS infection was ruled out. CONCLUSIONS: Special attention must be paid to patients with cancer who have symptoms similar to those seen in SARS. Although the WHO diagnostic criteria for SARS should be widely accepted, they are not definite or practical in certain populations.