Carbon nanotubes (CNTs) are frequently used as torsional devices in nanoelectromechanical systems; thus it is necessary to gain a thorough understanding of the mechanical behavior of tubes under torsion. In this paper, molecular dynamics simulations are carried out to investigate the torsional buckling of single-walled CNTs completely filled with copper atoms. Results show that, due to metal filling, the torsional rigidity of tubes can be dramatically enhanced and the critical torsional angles of filled tubes can be 2–4 times as high as those of empty ones. Furthermore, due to structural asymmetry in chiral metal-filled tubes, there exists a dependence of the torsional behavior on loading directions. The torsional response of metal-filled tubes is dependent on both tube chirality and loading direction. The microstructure of metal atoms may have a strong influence on the mechanical deformation of metal-filled tubes. These results can provide useful guidelines on the application of CNTs as torsional devices, especially in the case where high torsional stability is required.
Epoxy resin based double layer absorbing coatings were prepared, employing carbonyl iron and carbon black as original absorbents in the matching layer and absorbing layer respectively. Carbon fibre powders (CFPs) were introduced as additional absorbent in the two layers. The absorbers were tested to investigate their absorbing performances, including SEM, electromagnetic parameters and reflection loss. The advantage of adding CFP to the absorbing layer in improving the microwave performance was more obvious than that to matching layer. Results showed that an optimal content of CFP/carbon black/epoxy resin in the absorbing layer was 0?25 : 0?25 : 1 with a bandwidth (reflection loss ,210 dB) of 4?5 GHz. The absorption peak shifted to lower frequency when the content of CFP increased, as explained by Maxwell-Garnett equation and quarter wavelength resonance equation. The extra addition of CFP to the coatings was verified to be effective in controlling the wave absorbing properties.
Chromatin modifier metastasis-associated protein 1 (MTA1), closely correlated with the development and progression in breast cancer, has a vital role in multiple cellular processes, including gene expression and cell homeostasis. Although MTA1 is a stress-responsive gene, its role in genotoxic adaptation remains unexplored. The current study sought to investigate the role of MTA1 and its O-GlcNAc modification in breast cancer cells genotoxic adaptation by using quantitative proteomics, ChIP-seq, transcriptome analysis, loss-and gain-of-functions experiments. We demonstrate that O-GlcNAc modification promotes MTA1 to interact with chromatin and regulates target gene expression, contributing to breast cancer cell genotoxic adaptation. MTA1 is modified with O-GlcNAc residues at serine 237/241/246 in adriamycin adaptive breast cancer cells and that modification improves the genome-wide interactions of MTA1 with gene promotor regions by enhancing its association with nucleosome remodeling and histone deacetylation (NuRD) complex. Further, O-GlcNAc- modulated MTA1 chromatin-binding influences the specific transcriptional regulation of genes involved in the adaptation of breast cancer cells to genotoxic stress. Our findings reveal a previously unrecognized role of O-GlcNAc MTA1 in transcriptional regulation and suggest that O-GlcNAc modification is a promising therapeutic target to overcome chemoresistance in breast cancers.
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