Chao-Yang Liu

This study aims to propose and evaluate DR-CycleGAN, a disentangled unsupervised network by introducing a novel content-consistency loss, for removing arterial-phase motion artifacts in gadoxetic acid-enhanced liver MRI examinations. From June 2020 to July 2021, gadoxetic acid-enhanced liver MRI data were retrospectively collected in this center to establish training and testing datasets. Motion artifacts were semi-quantitatively assessed using a five-point Likert scale (1 = no artifact, 2 = mild, 3 = moderate, 4 = severe, and 5 = non-diagnostic) and quantitatively evaluated using the structural similarity index (SSIM) and peak signal-to-noise ratio (PSNR). The datasets comprised a training dataset (308 examinations, including 58 examinations with artifact grade = 1 and 250 examinations with artifact grade ≥ 2), a paired test dataset (320 examinations, including 160 examinations with artifact grade = 1 and paired 160 examinations with simulated motion artifacts of grade ≥ 2), and an unpaired test dataset (474 examinations with artifact grade ranging from 1 to 5). The performance of DR-CycleGAN was evaluated and compared with a state-of-the-art network, Cycle-MedGAN V2.0. As a result, in the paired test dataset, DR-CycleGAN demonstrated significantly higher SSIM and PSNR values and lower motion artifact grades compared to Cycle-MedGAN V2.0 (0.89 ± 0.07 vs. 0.84 ± 0.09, 32.88 ± 2.11 vs. 30.81 ± 2.64, and 2.7 ± 0.7 vs. 3.0 ± 0.9, respectively; p < 0.001 each). In the unpaired test dataset, DR-CycleGAN also exhibited a superior motion artifact correction performance, resulting in a significant decrease in motion artifact grades from 2.9 ± 1.3 to 2.0 ± 0.6 compared to Cycle-MedGAN V2.0 (to 2.4 ± 0.9, p < 0.001). In conclusion, DR-CycleGAN effectively reduces motion artifacts in the arterial phase images of gadoxetic acid-enhanced liver MRI examinations, offering the potential to enhance image quality.

A series of N‐unsubstituted/substituted fullerotetrahydroquinolines without a directly attached nitrogen atom were synthesized in moderate to good yields via a one‐pot two‐step reaction of [60]fullerene with arylamines and paraformaldehyde in the presence of trifluoromethanesulfonic acid and p‐toluenesulfonic acid monohydrate. Aromatic primary amines produce N‐unsubstituted fullereotetrahydroquinolines, while aromatic secondary amines give N‐substituted fullereotetrahydroquinoline derivatives. As precursors, N‐unsubstituted fullerotetrahydroquinolines could be further derivatized by the N‐alkylation/acylation/carboamidation reactions to produce a large variety of N‐substituted fullerotetrahydroquinolines containing Cl, NO₂, C(O), and C(O)NH functional groups, which may have applications in the field of perovskite‐based solar cells. Plausible reaction pathways for the formation of N‐unsubstituted/substituted fullerotetrahydroquinolines were suggested to elucidate the above‐mentioned reaction process. magnified image

A series of scarce amino-substituted cyclopentafullerenes instead of the expected N-alkyl-2,5-disubstituted fulleropyrrolidines were synthesized in moderate to excellent yields via the simple one-step reaction of [60]fullerene with cheap and easily available β-substituted propionaldehydes and secondary amines in the absence/presence of magnesium perchlorate. The in situ generation of allylic amines from β-substituted propionaldehydes and secondary amines played a crucial role in the successful preparation of amino-substituted cyclopentafullerenes without additional carbons. With the addition of magnesium perchlorate, secondary amines containing ethyl group(s) could produce novel amino-substituted cyclopentafullerenes with two additional carbons. All the obtained cyclopentafullerenes displayed high stereoselectivity with cis isomers as the exclusive or major products. Plausible reaction mechanisms are proposed to elucidate the above-mentioned reaction process.

A facile one-step reaction of [60]fullerene with cinnamaldehydes and amines promoted by magnesium perchlorate/ferric perchlorate under air conditions afforded a series of rare amino-substituted cyclopentafullerenes in moderate to good yields. Stereoselectivity was readily achieved. Secondary amines exclusively produced N,N-disubstituted cyclopentafullerenes as cis isomers, while arylamines gave N-monosubstituted cyclopentafullerenes with a preference of cis isomers as major products. N-Monosubstituted cyclopentafullerenes could be further converted into other scarce cyclopentafullerenes in the presence of acid chloride or paraformaldehyde. A possible reaction pathway was proposed to elucidate the formation of amino-substituted cyclopentafullerenes.

A simple one‐step reaction of [60]fullerene with cinnamaldehydes and primary/secondary amines without the addition of any inorganic salts afforded rare arylvinyl‐substituted fulleropyrrolidines in moderate to good yields with high stereoselectivity. Secondary amines produced N ‐alkyl‐2/5‐arylvinyl fulleropyrrolidines with a preference of trans isomers as major products, while primary amines exclusively gave 2‐aryl‐5‐arylvinyl fulleropyrrolidines as cis isomers. A plausible formation mechanism for fulleropyrrolidines was proposed to elucidate the above reaction process.

The reaction of [60]fullerene with amines and 2,2-disubstituted acetaldehydes in the absence of metal salts afforded a series of novel fulleropyrrolidin-2-ols in moderate yields.

The magnesium perchlorate-mediated reaction of [60]fullerene with aldehydes and triethylamine generated a series of rare amino-substituted cyclopentafullerenes with high stereoselectivity.