RESUMO
Nanostructure morphologies of transition metal dichalcogenides (TMDs) are gaining much interest owing to their catalytic, sensing, and energy storage capabilities. Here, we report the synthesis of highly dense MoO2/MoS2 core-shell nanoparticles, a new form of TMD nanostructure, via chemical vapor deposition using new growth geometry where a thin film of MoO3 was used as a source substrate for Mo as opposed to using MoO3 powder used in conventional studies. To grow the MoO2/MoS2 core-shell nanoparticles, we precisely control the carrier gas flow rate and sulfur vapor introduction time with respect to the melting of a MoO3 thin film used for Mo precursor. Scanning electron microscope image shows dense coverage of nanoparticles of 50-120 nm in size. The transmission electron microscopy image shows that the nanoparticles consist of crystalline MoO2 core covered with a few layer MoS2 shell. Raman and energy dispersive spectroscopy characterizations further confirm the chemical composition of the nanoparticle containing MoO2 and MoS2. We discuss the growth conditions under which the nanoparticles grow and elucidate its growth mechanism. We also discuss how a small but controllable changes in growth condition could lead to other highly dense growth of vertical/lateral MoO2/MoS2 plates in both source and growth substrates due to the unique growth geometry used in this study.
RESUMO
BACKGROUND: Accurate identification of bacterial infections in patients presenting at the emergency department is crucial for early and rational antibiotic treatment. In this situation, using a cut-off of 0.25 microg/L for procalcitonin allows for carefully monitoring of febrile patients. Most previous studies have been performed with the reference B.R.A.H.M.S PCT KRYPTOR assay. The goal of this study was to compare this test with the VIDAS B.R.A.H.M.S PCT((R)) assay and to validate clinically relevant cut-off thresholds. METHODS: This prospective study was conducted in adults presenting to the emergency departments of a tertiary hospital. We included 305 consecutive patients that had procalcitonin requested. Procalcitonin was measured first with the KRYPTOR, then with the VIDAS systems. Statistical analysis consisted in Passing and Bablok and Bland-Altman plots. RESULTS: In the overall cohort, 176 patients had procalcitonin concentrations measured using both methods and were well correlated. The Bland-Altman plot exhibited a bias of 0.108 [95% confidence interval: -0.044 to 0.260]. The concordance at different procalcitonin cut-off thresholds, respectively of 0.1, 0.25, 0.5 and 2 microg/L, indicated that above 0.25 microg/L, the kappa coefficient was >0.80. CONCLUSIONS: A highly significant correlation was observed between the two automated assays. Procalcitonin concentrations obtained from both methods led to the same clinical interpretation.
