RESUMEN
Waste resource utilization of petroleum coke is crucial for achieving global carbon emission reduction. Herein, a series of N-doped microporous carbons were fabricated from petroleum coke using a one-pot synthesis method. The as-prepared samples had a large specific surface area (up to 2512 m2/g), a moderate-high N content (up to 4.82 at.%), and high population (55%) of ultra-micropores (<0.7 nm). Regulating the N content and ultra-microporosity led to efficient CO2 adsorption and separation. At ambient pressure, the optimal N-doped petroleum coke-based microporous carbon exhibited the highest CO2 uptake of 4.25 mmol/g at 25°C and 6.57 mmol/g at 0°C. These values are comparable or even better than those of numerous previously reported adsorbents prepared by multistep synthesis, primarily due to the existence of ultra-micropores. The sample exhibited excellent CO2/N2 selectivity at 25°C owing to the abundant basic pyridinic and pyrrolic N species; and showed superior CO2 adsorption-desorption cycling performance, which was maintained at 97% after 10 cycles at 25°C. Moreover, petroleum coke-based microporous carbon, with a considerably high specific surface area and hierarchical pore structure, exhibited excellent electrochemical performance over the N-doped sample, maintaining a favorable specific capacitance of 233.25 F/g at 0.5 A/g in 6 mol/L KOH aqueous electrolyte. This study provides insight into the influence of N-doping on the porous properties of petroleum coke-based carbon. Furthermore, the as-prepared carbons were found to be promising adsorbents for CO2 adsorption, CO2/N2 separation and electrochemical application.
Asunto(s)
Carbono , Coque , Carbono/química , Dióxido de Carbono/química , Adsorción , PorosidadRESUMEN
Background Although metastasis of lateral cervical lymph nodes (LNs) is common in papillary thyroid carcinoma (PTC), correctly diagnosing small metastatic LNs with US remains challenging. The use of contrast-enhanced US (CEUS), especially the postvascular phase of CEUS with perfluorobutane contrast material, might contribute to improved diagnosis of metastatic LNs in PTC. Purpose To assess the diagnostic value of the postvascular phase of CEUS with perfluorobutane in suspicious small lateral cervical LNs (short-axis diameter ≤8 mm) in patients with PTC. Materials and Methods This single-center study prospectively enrolled consecutive participants with confirmed PTC and suspicious LNs at US from October 2020 to October 2021. All participants underwent CEUS, 1 week before biopsy or surgery, with intravenous perfluorobutane contrast material to visualize the LNs in the vascular phase (5-60 seconds after injection) and postvascular phase (10-30 minutes after injection). The reference standard was cytologic and surgical histologic assessment of the LNs. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of sonographic features were calculated, and the diagnostic performance of US, CEUS, and the combination of postvascular phase and US features was assessed using multivariable logistic regression models. Results A total of 135 participants (median age, 36 years [IQR, 30-46 years]; 100 women) with 161 suspicious LNs at US were evaluated, including 67 metastatic and 94 benign LNs. The specificity of perfusion defect as a sonographic feature in the vascular phase reached 96% (90 of 94 LNs), and the negative predictive value of non-isoenhancement (ie, hypoenhancement, partial enhancement, and no enhancement) in the postvascular phase reached 100% (83 of 83 LNs). The area under the receiver operating characteristic curve (AUC) of the combination of postvascular phase and US features was 0.94 (95% CI: 0.89, 0.97), significantly higher than that of US features alone (AUC, 0.73; 95% CI: 0.65, 0.79; P < .001). Conclusion The postvascular phase of CEUS with perfluorobutane demonstrated excellent performance for diagnosing suspicious small lateral cervical LNs in participants with PTC. Published under a CC BY 4.0 license Supplemental material is available for this article. See also the editorial by Gunabushanam in this issue.