The ethylene glycol-mediated sol-gel synthesis of nano AlF3: structural and acidic properties after different post treatments.

In this work, the structure and surface acidity of nano AlF3 prepared by the ethylene glycol-mediated sol-gel process, followed by different post treatments including post-fluorination and calcination, were systematically investigated. FT-IR, elemental analysis, XPS and TG-DTA-MS results indicate the ethylene glycol strongly interacts with the as-prepared AlF3 precursor, thus stabilizing the formed nano particles. MAS NMR spectroscopy combined with in situ FT-IR and HRTEM techniques reveal that AlF6, AlO6-xFx and AlO6 species are present in the resulting X-ray amorphous nano AlF3. The fraction of AlF6 species formed after post-fluorination significantly increases, whereas more AlO6-xFx species are formed just after calcination. After a comparable post-fluorination treatment, the CHClF2 dismutation activity at room temperature indicates that nano AlF3 prepared according the ethylene glycol-mediated route does not possess the same super-strong acidity as HS-AlF3 prepared by the fluorolytic sol-gel method, although NH3-TPD and N2-sorption results indicate larger BET surface areas and high concentration of acid sites for the former as compared to the latter. This might be rationalized based on the absence of terminal fluorine species and the presence of a significant number of AlO6-xFx and AlO6 species in the resulting nano AlF3 as revealed by 27Al, 19F MAS NMR and HRTEM. An interesting consequence is that these oxygen-containing species stabilize the microstructure of AlF3 formed, resulting in improved thermal stability of these phases as compared to "classically" prepared HS-AlF3.

Diagnostic performance of quantitative and qualitative elastography for the differentiation of benign and malignant cervical lymph nodes: A protocol for systematic review and meta-analysis.

BACKGROUND: Studies have shown inconsistent results regarding the diagnostic performance of quantitative and qualitative elastography for the differentiation of benign and malignant cervical lymph nodes. This meta-analysis aimed to estimate the diagnostic performance of ultrasound elastography in patients with cervical lymphadenopathy. METHODS: We will search PubMed, Web of Science, Cochrane Library, and Chinese biomedical databases from their inceptions to the May 30, 2021, without language restrictions. Two authors will independently carry out searching literature records, scanning titles and abstracts, full texts, collecting data, and assessing risk of bias. Review Manager 5.2 and Stata14.0 software will be used for data analysis. RESULTS: This systematic review will determine the accuracy of shear wave elastography and strain elastography in the differential diagnosis between benign and malignant cervical lymph nodes. CONCLUSION: Its findings will provide helpful evidence for the accuracy of shear wave elastography and strain elastography in the differential diagnosis between benign and malignant cervical lymph nodes. SYSTEMATIC REVIEW REGISTRATION: INPLASY202150109.

Diagnostic accuracy of three-dimensional contrast-enhanced ultrasound for focal liver lesions: A protocol for systematic review and meta-analysis.

BACKGROUND: Contrast-enhanced ultrasound (CEUS) examination is a well-established technique for this purpose with several unique advantages. It is a real-time technology with high temporal resolution. With its unique ability to detect microvascular perfusion, it helps in better characterization of FLL.[1-4] Three-dimensional (3D) CEUS with quantitative analysis is updated in recent years. 3D-CEUS is a new ultrasonic diagnostic technique, which can observe the nourishing vessels of lesions from multiple angles. Previous studies showed that 3D-CEUS can detect tumor nourishing vessels to differentiate benign from malignant focal liver lesions (FLLs). However, the results of these studies have been contradictory. Therefore, this meta-analysis tested the hypothesis that 3D-CEUS is accurate in distinguishing benign and malignant FLLs. METHODS: We will search PubMed, Web of Science, Cochrane Library, and Chinese biomedical databases from their inceptions to the April 30, 2021, without language restrictions. Two authors will independently carry out searching literature records, scanning titles and abstracts, full texts, collecting data, and assessing risk of bias. Review Manager 5.2 and Stata14.0 software will be used for data analysis. RESULTS: This systematic review will determine the accuracy of 3D-CEUS in the differential diagnosis between benign and malignant FLLs. CONCLUSION: Its findings will provide helpful evidence for the accuracy of 3D-CEUS in the differential diagnosis between benign and malignant FLLs. SYSTEMATIC REVIEW REGISTRATION: INPLASY202150096.