Tensile strain and compress strain can greatly affect the thermal conductivity of graphene nanoribbons (GNRs). However, the effect of GNRs under shear strain, which is also one of the main strain effect, has not been studied systematically yet. In this work, we employ reverse nonequilibrium molecular dynamics (RNEMD) to the systematical study of the thermal conductivity of GNRs (with model size of 4 nm × 15 nm) under the shear strain. Our studies show that the thermal conductivity of GNRs is not sensitive to the shear strain, and the thermal conductivity decreases only 12–16% before the pristine structure is broken. Furthermore, the phonon frequency and the change of the micro-structure of GNRs, such as band angel and bond length, are analyzed to explore the tendency of thermal conductivity. The results show that the main influence of shear strain is on the in-plane phonon density of states (PDOS), whose G band (higher frequency peaks) moved to the low frequency, thus the thermal conductivity is decreased. The unique thermal properties of GNRs under shear strains suggest their great potentials for graphene nanodevices and great potentials in the thermal managements and thermoelectric applications.

We perform classical molecular dynamics to investigate the effects of mechanical strain on singlelayer black phosphorus nanoresonators at different temperatures. We find that the resonant frequency is highly anisotropic in black phosphorus due to its intrinsic puckered configuration, and that the quality factor in the armchair direction is higher than in the zigzag direction at room temperature. The quality factors are also found to be intrinsically larger than graphene and MoS2 nanoresonators. The quality factors can be increased by more than a factor of two by applying tensile strain, with uniaxial strain in the armchair direction being most effective. However, there is an upper bound for the quality factor increase due to nonlinear effects at large strains, after which the quality factor decreases. The tension induced nonlinear effect is stronger along the zigzag direction, resulting in a smaller maximum strain for quality factor enhancement. Black phosphorus (BP) is a new two-dimensional nanomaterial that is comprised of atomic layers of phosphorus stacked via van der Waals forces 1 . BP brings a number of unique properties unavailable in other two-dimensional crystals material. For example, BP has anisotropic properties due to its puckered configuration. [2][3][4][5] While most existing experiments have been focused on potential electronic applications of BP 6-8 , a recent experiment showed that the resonant vibration response of BP resonators (BPR) can be achieved at a very high frequency. 9 However, there have been no theoretical studies on the intrinsic dissipation in BPRs to-date. In particular, it is interesting and important to characterize the effects of mechanical strain on the quality (Q)-factors of BPRs given its anisotropic crystal structure, and furthermore considering that mechanical strain can act as an efficient tool to manipulate various physical properties in the BP structure. 10-17 For example, a large uniaxial strain in the direction normal to the SLBP plane can even induce a semiconductor-metal transition. [18][19][20][21] We thus investigate the mechanical strain effect on the BPRs of armchair and zigzag directions, at different temperatures.In this work, we examine the effect of mechanical tension on single-layer BPR (SLBPR) via classical molecular dynamical (MD) simulations. Both uniaxial and biaxial tension are found to increase the quality factor of the SLBPR, as the resonant frequency is enhanced by the applied tension. However, the Q-factor decreases beyond a critical strain value due to the introduction of nonlinear energy dissipation, which becomes dominant at large tensile strains. As a result, there is a critical strain at which the quality factor reaches the maximum value, which is about 4% and 8% at 50 K for mechanical tension along the zigzag and armchair directions, respectively. We find that the nonlinear dissipation is stronger if the BPR is stretched along the zigzag direction, which results in a smaller critical strain. Fig. 1 shows the structure of SLBP of dimension 5...

The nucleoporin Nup124p is a host protein required for the nuclear import of both, retrotransposon Tf1-Gag as well as the retroviral HIV-1 Vpr in fission yeast. The human nucleoporin Nup153 and the Saccharomyces cerevisiae Nup1p were identified as orthologs of Nup124p. In this study, we show that all three nucleoporins share a large FG/FXFG-repeat domain and a C-terminal peptide sequence, GRKIxxxxxRRKx, that are absolutely essential for Tf1 retrotransposition. Though the FXFG domain was essential, the FXFG repeats themselves could be eliminated without loss of retrotransposon activity, suggesting the existence of a common element unrelated to FG/FXFG motifs. The Nup124p C-terminal peptide, GRKIAVPRSRRKR, was extremely sensitive to certain single amino acid changes within stretches of the basic residues. On the basis of our comparative study of Nup124p, Nup1p, and Nup153 domains, we have developed peptides that specifically knockdown retrotransposon activity by disengaging the Tf1-Gag from its host nuclear transport machinery without any harmful consequence to the host itself. Our results imply that those domains challenged a specific pathway affecting Tf1 transposition. Although full-length Nup1p or Nup153 does not complement Nup124p, the functionality of their conserved domains with reference to Tf1 activity suggests that these three proteins evolved from a common ancestor.

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