RESUMO
The stochastic tunneling-basin hopping method (STUN-BH) was utilized to obtain the most stable peptide S7 configuration (Ac-Ser-Ser-Phe-Pro-Gln-Pro-Asn-CONH2) adsorbed on Au(111) facet. After the most stable S7 configuration was found, molecular dynamics (MD) simulation was conducted to investigate the thermal stability between S7 and Au facet at 300 K in both vacuum and water environment. Moreover, further design sets of peptide sequences on Au(111) facet were used to compare with S7. All molecular simulations were carried out by the large-scale atomic/molecular massively parallel simulator (LAMMPS). The Amber99sb-ILDN force field was employed for modeling the interatomic interaction of peptides, and the TIP3P water was used for the water environment. The CHARMM-METAL force field was introduced to model the S7, PF8 (Ac-Pro-Phe-Ser-Pro-Phe-Ser-Pro-Phe-CONH2) and FS8 (Ac-Phe-Ser-Phe-Ser-Phe-Ser-Phe-Ser-CONH2) interactions with Au(111). The MD simulation results demonstrate that the morphology of Pro affects the adsorption stability of Phe. Therefore, we designed two sequences, PF8 and FS8, to confirm our simulation result through experiment. The present study also develops a novel low-temperature plasma synthesis method to evaluate the facet selecting performance of the designed peptide sequences of S7, PF8, and FS8. The experimental results suggest that the reduced Au atom seed is captured with the designed peptide sequences and slowing growing under room temperature for 72 hours. The experimental results are in the excellent agreement with the simulation finding that the Pro in the designed peptide sequences plays a critical role in the facet selection for Au atom stacking.
RESUMO
OBJECTIVE: To evaluate the clinical value of retrospective electrocardiogram (ECG) -editing technique in dual-source computed tomography (CT) coronary angiography in patients with arrhythmia. METHODS: Totally 73 patients with arrhythmia during dual-source CT coronary angiography were included into this study. A retrospective gating technique and ECG-editing technique (Insert Sync; Disable Sync; Delete Sync; Shift R-peak) were used in patients who needed ECG-editing. Two experienced radiologists evaluated in consensus all pre-editing and post-editing reconstructed images and recorded scores according to the American Heart Association guidelines on coronary segmentation on a per segment basis. Image quality of all coronary segments was assessed using a four-point grading scale from excellent (4 scores) to non-assessable (1 score) . RESULTS: The overall mean image quality of 34 patients who did not need ECG-editing was 3.42 ± 0.20. In 39 patients who needed ECG-editing, the overall mean image quality before and after ECG-editing was 2.39?0.37 and 3.22?0.24. The mean image quality in every segment between pre-editing and post-editing was also significantly different (P<0.01) . CONCLUSION: ECG-editing technique can remarkably improve image quality of coronary artery segments by reducing or even eliminating the artifact produced by arrhythmia during dual-source CT coronary angiography.
