Insights into enhanced immobilization of uranyl carbonate from seawater by Fe-doped MXene.

Extracting uranium from seawater not only reduces radioactive contamination in seawater but also provides a source of uranium energy. However, due to the low concentration of uranium in seawater and the high salinity of seawater, extraction of uranium from seawater is challenging. In this work, we demonstrated a simple strategy to synthesize Fe-doped MXene (Fe@Ti3C2Tx) via a hydrothermal method and applied for uranium enrichment in seawater. The Fe@Ti3C2Tx exhibited excellent adsorption performance in high salinity environments. The removal capacity of Fe@Ti3C2Tx was determined to be 526.6 mg/g for UO2(CO3)22- at 328 K with quick reaction equilibrium (∼ 30 min). Kinetic and thermodynamic analyses of UO2(CO3)22- elimination process on Fe@Ti3C2Tx surface revealed it to be a spontaneous and endothermic single-phase elimination process. FT-IR and XPS analyses further indicated that the removal mechanism of UO2(CO3)22- by Fe@Ti3C2Tx was surface complexation. Our study suggests that Fe@Ti3C2Tx can provide a feasible solution for uranium enrichment in seawater.

COF-based membranes for liquid phase separation: Preparation, mechanism and perspective.

Covalent organic frameworks (COFs) are a new kind of crystalline porous materials composed of organic molecules connected by covalent bonds, processes the characteristics of low density, large specific surface area, adjustable pore size and structure, and easy to functionalize, which have been widely used in the field of membrane separation technology. Recently, there are more and more researches focusing on the preparation methods, separation application, and mechanism of COF membranes, which need to be further summarized and compared. In this review, we primarily summarized several conventional preparation methods, such as two-phase interfacial polymerization, in-situ growth on substrate, unidirectional diffusion method, layer-by-layer assembly method, mixed matrix membranes, and so on. The advantages and disadvantages of each method are briefly summarized. The application potential of COF membrane in liquid separation are introduced from four aspects: dyeing wastewater treatment, heavy metal removal, seawater desalination and oil-water separation. Then, the mechanisms including pore structure, hydrophilic/hydrophobic, electrostatic repulsion/attraction and Donnan effect are introduced. For the efficient removal of different kind of pollutions, researchers can select different ligands to construct membranes with specific pore size, hydrophily, salt or organic rejection ability and functional group. The ideas for the design and preparation of COF membranes are introduced. Finally, the future direction and challenges of the next generation of COF membranes in the field of separation are prospected.

The diagnostic performance of high-resolution magnetic resonance-vessel wall imaging in differentiating atherosclerosis-associated moyamoya vasculopathy from moyamoya disease.

OBJECTIVES: To evaluate the diagnostic performance of high-resolution magnetic resonance-vessel wall imaging (HRMR-VWI) in differentiating moyamoya disease (MMD) from atherosclerosis-associated moyamoya vasculopathy (AS-MMV) and investigate an accurate approach for the differential diagnosis. METHODS: Adult patients who were diagnosed as MMD or AS-MMV and underwent HRMR-VWI were retrospectively included. The three vessel wall features (outer diameter (OD), remodeling index (RI), and pattern of vessel wall thickening) of middle cerebral artery (MCA) in identifying MMD from AS-MMV were assessed and compared. Furthermore, subgroup analysis stratified by degree of luminal stenosis was performed and the cutoff values of different vessel wall features in differentiating MMD from AS-MMV were also calculated. RESULTS: A total of 265 patients (160 cases of MMD and 105 AS-MMV) were included. Patients with AS-MMV had greater OD and RI and were more likely to exhibit eccentric thickening of vessel wall compared to those with MMD (all p < 0.001). The ROC analysis showed that the AUC value of OD was greater than that of RI (0.912 vs. 0.889, p = 0.007) in differentiating MMD from AS-MMV, and their corresponding cutoff values were 1.77 mm and 0.27, respectively. And the AUC value of pattern of vessel wall thickening was 0.786 in non-occluded patients. With the increase of lumen stenosis, the discrimination power of the three indicators enhanced correspondingly. CONCLUSIONS: HRMR-VWI is valuable in distinguishing MMD from AS-MMV. The OD of MCA has better diagnostic performance in differentiating AS-MMV from MMD compared to RI and pattern of vessel wall thickening. CLINICAL RELEVANCE STATEMENT: The outer diameter of the involved artery proved to be both accurate and convenient in distinguishing atherosclerosis-associated moyamoya vasculopathy from moyamoya disease and may provide a quantitative reference for clinical diagnosis. KEY POINTS: High-resolution magnetic resonance-vessel wall imaging is valuable in distinguishing atherosclerosis-associated moyamoya vasculopathy from moyamoya disease. Compared to remodeling index and pattern of vessel wall thickening, outer diameter is more accurate in differentiating atherosclerosis-associated moyamoya vasculopathy from moyamoya disease. With the increase of lumen stenosis, the discrimination power of outer diameter, remodeling index, and pattern of vessel wall thickening enhanced correspondingly.