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- Samikannu, Ajaikumar, et al.
(author)
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Highly dispersed NbOPO4/SBA-15 as a versatile acid catalyst upon production of renewable jet-fuel from bio-based furanics via hydroxyalkylation-alkylation (HAA) and hydrodeoxygenation (HDO) reactions
- 2020
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In: Applied Catalysis B. - : Elsevier. - 0926-3373 .- 1873-3883. ; 272
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Journal article (peer-reviewed)abstract
- Herein, we report the synthesis of a highly active and mesoporous Brønsted acidic NbOPO4/SBA-15 catalyst. The prepared catalysts were thoroughly characterized by means of analytical techniques such as XRD, FT-IR, XPS, NH3-TPD, SEM-EDS, TEM, TGA, 31P-MAS-NMR and N2-physisorption. The H3PO4 free deposition method was found to be effective for preserving the structure of Silica based carrier. In terms of catalytic performance, these materials demonstrated high activity upon C-C coupling of 2-methyl furan with carbonyl compounds and outperforming bulk NbOPO4, Nb2O5/SBA-15 and traditional solid acid catalysts (Al-MCM-41, Si/Al and H-ZSM-5). The NbOPO4/SBA-15 catalysts were stable and maintained high activity upon reuse and continuous operation (∼65 h). Furthermore, the Pd loaded counterparts (Pd/NbOPO4/SBA-15 and Pd/Nb2O5/SBA-15) also functioned as bifunctional catalysts and exhibited excellent activity upon subsequent hydrodeoxygenation of C-C coupling products. Most importantly, in terms of jet-fuel range hydrocarbons selectivity, these catalysts outperformed monofunctional Pd/carbon and aluminosilicate based bifunctional catalysts.
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| 2. |
- Sandstedt, Mårten, et al.
(author)
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Improved coronary calcification quantification using photon-counting-detector CT : an ex vivo study in cadaveric specimens
- 2021
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In: European Radiology. - : SPRINGER. - 0938-7994 .- 1432-1084. ; 31:9, s. 6621-6630
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Journal article (peer-reviewed)abstract
- Objectives To compare the accuracy of coronary calcium quantification of cadaveric specimens imaged from a photon-counting detector (PCD)-CT and an energy-integrating detector (EID)-CT. Methods Excised coronary specimens were scanned on a PCD-CT scanner, using both the PCD and EID subsystems. The scanning and reconstruction parameters for EID-CT and PCD-CT were matched: 120 kV, 9.3-9.4 mGy CTDIvol, and a quantitative kernel (D50). PCD-CT images were also reconstructed using a sharper kernel (D60). Scanning the same specimens using micro-CT served as a reference standard for calcified volumes. Calcifications were segmented with a half-maximum thresholding technique. Segmented calcified volume differences were analyzed using the Friedman test and post hoc pairwise Wilcoxon signed rank test with the Bonferroni correction. Image noise measurements were compared between EID-CT and PCD-CT with a repeated-measures ANOVA test and post hoc pairwise comparison with the Bonferroni correction. A p < 0.05 was considered statistically significant. Results The volume measurements in 12/13 calcifications followed a similar trend: EID-D50 > PCD-D50 > PCD-D60 > micro-CT. The median calcified volumes in EID-D50, PCD-D50, PCD-D60, and micro-CT were 22.1 (IQR 10.2-64.8), 21.0 (IQR 9.0-56.5), 18.2 (IQR 8.3-49.3), and 14.6 (IQR 5.1-42.4) mm(3), respectively (p < 0.05 for all pairwise comparisons). The average image noise in EID-D50, PCD-D50, and PCD-D60 was 60.4 (+/- 3.5), 56.0 (+/- 4.2), and 113.6 (+/- 8.5) HU, respectively (p < 0.01 for all pairwise comparisons). Conclusion The PCT-CT system quantified coronary calcifications more accurately than EID-CT, and a sharp PCD-CT kernel further improved the accuracy. The PCD-CT images exhibited lower noise than the EID-CT images.
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