分类： 天文学 >> 天文学 提交时间： 2023-02-19
Nan Liu
Jens Barosch
Larry R. Nittler
Conel M. O D. Alexander
Jianhua Wang
Sergio Cristallo
Maurizio Busso
Sara Palmerini
摘要： We report NanoSIMS Si and Mg-Al isotopic data (and C, N, and Ti isotopic data when available) for 85 submicron- to micron-sized presolar SiC grains from the CM2 Murchison meteorite, including 60 MS, 8 AB1, 8 X, 7 AB2, and 2 Y grains. The MS and Y grain data demonstrate that (1) C and N contamination mainly appears as surface contamination, and sufficient presputtering is needed to expose a clean grain surface for obtaining intrinsic C and N signals, and (2) Mg and Al contamination appears as adjacent grains and rims, and high-resolution imaging and the choice of small regions of interest during data reduction together are effective in suppressing the contamination. Our results strongly indicate that previous studies on presolar SiC grains could have sampled differing degrees of contamination for C, N, Mg, and Al. Compared to the literature data, our new MS and Y grains are in better agreement with carbon star observations for both the C and N isotopic ratios. By comparing our new, tighter distributions of 12C/13C, 14N/15N, and initial 26Al/27Al ratios for MS and Y grains with FRUITY AGB stellar models, we provide more stringent constraints on the occurrence of cool bottom processing and the production of 26Al in N-type carbon stars, classical asymptotic giant branch stars.
分类： 工程与技术科学 >> 工程与技术科学其他学科 提交时间： 2023-01-03 合作期刊: 《2022年第三届艺术设计、传播与工程科学研讨会》
摘要： In order to better realize the cultural and regional development of urban furniture design, achieve the purpose of promoting minority culture and inheriting excellent regional culture. This paper from the aspects of pattern, color, modelling three artistic features analysis was carried out on the architectural culture of dong, and build according to the principles and methods of dong architectural culture gene mapping, extract the cultural factor, after in artistic exaggeration, deformation, increase, decrease, finally the corresponding cultural factor into urban furniture design, The city furniture which not only meets the functional needs but also has the cultural implication is obtained. While spreading and carrying forward national culture, it also provides a new design idea for urban furniture design.
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