Regulating Efficient and Selective Single-atom Catalysts for Electrocatalytic CO2 Reduction.

Anchoring transition metal (TM) atoms on suitable substrates to form single-atom catalysts (SACs) is a novel approach to constructing electrocatalysts. Graphdiyne with sp-sp2 hybridized carbon atoms and uniformly distributed pores have been considered as a potential carbon material for supporting metal atoms in a variety of catalytic processes. Herein, density functional theory (DFT) calculations were performed to study the single TM atom anchoring on graphdiyne (TM1 -GDY, TM=Sc, Ti, V, Cr, Mn, Co and Cu) as the catalysts for CO2 reduction. After anchoring metal atoms on GDY, the catalytic activity of TM1 -GDY (TM=Mn, Co and Cu) for CO2 reduction reaction (CO2 RR) are significantly improved comparing with the pristine GDY. Among the studied TM1 -GDY, Cu1 -GDY shows excellent electrocatalytic activity for CO2 reduction for which the product is HCOOH and the limiting potential (UL ) is -0.16 V. Mn1 -GDY and Co1 -GDY exhibit superior catalytic selectivity for CO2 reduction to CH4 with UL of -0.62 and -0.34 V, respectively. The hydrogen evolution reaction (HER) by TM1 -GDY (TM=Mn, Co and Cu) occurs on carbon atoms, while the active sites of CO2 RR are the transition metal atoms . The present work is expected to provide a solid theoretical basis for CO2 conversion into valuable hydrocarbons.

Usefulness of the Contrast-Enhanced Ultrasound Liver Imaging Reporting and Data System in Diagnosing Focal Liver Lesions by Inexperienced Radiologists.

OBJECTIVES: To evaluate the usefulness of the contrast-enhanced ultrasound (CEUS) Liver Imaging Reporting and Data System (LI-RADS) in diagnosing focal liver lesions (FLLs) by inexperienced radiologists. METHODS: Images and clinical data from 258 patients at risk for hepatocellular carcinoma who underwent CEUS were collected retrospectively. Two trained inexperienced radiologists and 2 experienced radiologists reviewed all CEUS clips. Each inexperienced radiologist assigned a CEUS LI-RADS category for each observation and labeled it benign or malignant independently. Each experienced radiologist labeled each lesion malignant or benign independently using a conventional diagnostic method. Interobserver agreement of CEUS LI-RADS was analyzed by the κ test. The overall diagnostic accuracy of the LI-RADS category and conventional diagnosis was described by the sensitivity, specificity, positive predictive value, and negative predictive value. All test results were considered significant at P < .05. RESULTS: A κ value of 0.774 indicated that the CEUS LI-RADS algorithm resulted in substantial consistency between the inexperienced radiologists. For the diagnosis of hepatocellular carcinoma, the sensitivity, specificity, positive predictive value, and negative predictive value were improved significantly in inexperienced radiologists using the CEUS LI-RADS compared to conventional methods. The overall diagnostic accuracy of the experienced radiologists was almost equal to that of CEUS LI-RADS categories assigned by the inexperienced radiologists. CONCLUSIONS: The CEUS LI-RADS algorithm can not only obtain substantial consistency among inexperienced radiologists but also have excellent diagnostic efficacy in the differentiation of benign from malignant FLLs compared to conventional methods. As a comprehensive algorithm, the CEUS LI-RADS can act as a guide for trainees in learning how to diagnose FLLs.

Comparison of Contrast-Enhanced Ultrasound versus Contrast-Enhanced Magnetic Resonance Imaging for the Diagnosis of Focal Liver Lesions Using the Liver Imaging Reporting and Data System.

The aim of this retrospective study was to evaluate the Liver Imaging Reporting and Data System (LI-RADS) categorization of focal liver lesions (FLLs) on contrast-enhanced ultrasound (CEUS) in comparison with contrast-enhanced magnetic resonance imaging (CE-MRI). A total of 63 patients with 84 FLLs were included in the final study population, after review of the electronic medical records and clinical data. Two trained radiologists evaluated all CEUS and CE-MRI images independently. They assigned a LI-RADS category to each FLL and assessed major features based on CEUS LI-RADS Version 2017 and computed tomography/MRI LI-RADS Version 2018. The generalized estimating equation method was used to compare the diagnostic performance of the LI-RADS algorithm between CEUS and CE-MRI. The sensitivity of LR-5/LR-TIV (tumor in vein) categories for diagnosing hepatocellular carcinoma (HCC) differed significantly between CEUS and CE-MRI (88.9% [40/45], 95% confidence interval [CI]: 76.5%-95.2%), versus 64.4% (29/45; 95% CI: 49.8%-76.8%), p = 0.006; 82.2% (37/45; 95% CI: 68.7%-90.7%), versus 62.2% (28/45; 95% CI: 47.6%-74.9%), p = 0.034. Inter-observer agreement was substantial for assigning LR-5 on both CEUS and CE-MRI. For both reviewers, there was a higher frequency of LR-5 (44.0% vs. 25.0%, p = 0.009; 42.9% vs. 26.2%, p = 0.023) in CEUS compared with CE-MRI. Arterial phase hyper-enhancement (APHE) was less frequently observed on CEUS than on CE-MRI (46.4% vs. 61.9%, p = 0.044). However, the washout appearance was observed more frequently on CEUS than on CE-MRI (50.0% vs. 28.6%, p = 0.004). Inter-observer agreement between the two reviewers on APHE and washout appearance was excellent for both CEUS and CE-MRI. These findings suggest that CEUS had a much higher sensitivity than CE-MRI in the diagnosis of HCC using LI-RADS, and although the frequencies of major features differed, inter-observer agreement between the two reviewers on major features of HCC was excellent for both CEUS and CE-MRI.