RESUMEN
Advanced battery electrodes require a cautious design of microscale particles with built-in nanoscale features to exploit the advantages of both micro- and nano-particles relative to their performance attributes. Herein, the dynamic behavior of nanosized Sn clusters and their host pores in carbon nanofiber) during sodiation and desodiation is revealed using a state-of-the-art 3D electron microscopic reconstruction technique. For the first time, the anomalous expansion of Sn clusters after desodiation is observed owing to the aggregation of clusters/single atoms. Pore connectivity is retained despite the anomalous expansion, suggesting inhibition of solid electrolyte interface formation in the sub-2-nm pores. Taking advantage of the built-in nanoconfinement feature, the CNF film with nanometer-sized interconnected pores hosting Sn clusters (≈2 nm) enables high utilization (95% at a high rate of 1 A g-1) of Sn active sites while maintaining an improved initial Coulombic efficiency of 87%. The findings provide insights into electrochemical reactions in a confined space and a guiding principle in electrode design for battery applications.
RESUMEN
OBJECTIVE: To compare the performances of fecal occult blood quantitive testing instrument and colloidal gold strip method in colorectal cancer screening. METHODS: A representative random population of 9000 subjects aging between 40 and 74 years old were selected from Xuxiang, Haining city, Zhejiang province, by random cluster sampling method in year 2011. The fecal samples from each subject were separately detected by the two methods, namely fecal occult blood quantitive testing instrument and colloidal gold strip method. The positive result was standardized by hemoglobin concentration (HGB) ≥ 100 ng/ml under the application of quantitive testing instrument, or color-developing by colloidal gold strip method. The positive subjects from either method would be provided a further colonoscopy examination for pathological diagnosis. The positive rate and consistency of the two methods were compared, as well as the positive predictive value and population detecting rate of the colorectal cancer and adenoma. RESULTS: A total of 6475 (71.9%) subjects submitted their two fecal samples according to our requirement in 9000 subjects. There were separately 319 positive cases (4.9%) and 146 positive cases (2.3%) by the performances of fecal occult blood quantitive testing instrument and colloidal gold strip method, including 45 positive in both tests (Kappa = 0.168, 95%CI:0.119-0.217).184 out of the 319 positive cases (57.7%) in the test by quantitive testing instrument and 89 out of 146 positive cases (61.0%) in the test by colloidal gold strip method received the colonoscopy examination. There were no significant statistical differences between the two methods in the positive predictive value of colorectal cancer (P > 0.05) , developing adenoma and non-developing adenoma.However, the population detecting rate of the colorectal cancer and developing adenoma were higher in the test by quantitive testing instrument (26 cases, 0.402%) than it in the test by colloidal gold strip method (10 cases, 0.154%). The difference showed statistical significance (χ(2) = 7.131, P < 0.01). CONCLUSION: The performances of fecal occult blood quantitive testing instrument might be better than colloidal gold strip method in colorectal cancer screening. However, the results need to be further verified.