Polytypism and Unexpected Strong Interlayer Coupling of two-Dimensional Layered ReS2

The anisotropic two-dimensional (2D) van der Waals (vdW) layered materials, with both scientific interest and potential application, have one more dimension to tune the properties than the isotropic 2D materials. The interlayer vdW coupling determines the properties of 2D multi-layer materials by varying stacking orders. As an important representative anisotropic 2D materials, multilayer rhenium disulfide (ReS2) was expected to be random stacking and lack of interlayer coupling. Here, we demonstrate two stable stacking orders (aa and a-b) of N layer (NL, N>1) ReS2 from ultralow-frequency and high-frequency Raman spectroscopy, photoluminescence spectroscopy and first-principles density functional theory calculation. Two interlayer shear modes are observed in aa-stacked NL-ReS2 while only one interlayer shear mode appears in a-b-stacked NL-ReS2, suggesting anisotropic-like and isotropic-like stacking orders in aa- and a-b-stacked NL-ReS2, respectively. The frequency of the interlayer shear and breathing modes reveals unexpected strong interlayer coupling in aa- and a-b-NL-ReS2, the force constants of which are 55-90% to those of multilayer MoS2. The observation of strong interlayer coupling and polytypism in multi-layer ReS2 stimulate future studies on the structure, electronic and optical properties of other 2D anisotropic materials

A visible, targeted high-efficiency gene delivery and transfection strategy

<p>Abstract</p> <p>Background</p> <p>To enhance myocardial angiogenic gene expression, a novel gene delivery strategy was tested. Direct intramyocardial injection of an angiogenic gene with microbubbles and insonation were applied in a dog animal model. Dogs received one of the four different treatments in conjunction with either the enhanced green fluorescence protein (EGFP) gene or the hepatocyte growth factor (HGF) gene: gene with microbubbles (MB) and ultrasound (US); gene with US; gene with MB; or the gene alone.</p> <p>Results</p> <p>Distribution of MB and the gene in the myocardium was visualized during the experiment. Compared with the EGFP gene group, an average 14.7-fold enhancement in gene expression was achieved in the EGFP+MB/US group (P < 0.01). Compared with the HGF gene group, an average 10.7-fold enhancement in gene expression was achieved in the HGF+MB/US group (P < 0.01). In addition, capillary density increased from 20.8 ± 3.4/mm2 in the HGF gene group to 146.7 ± 31.4/mm2 in HGF+MB/US group (P < 0.01).</p> <p>Conclusions</p> <p>Thus, direct intramyocardial injection of an angiogenic gene in conjunction with microbubbles plus insonation synergistically enhances angiogenesis. This method offers an observable gene delivery procedure with enhanced expression efficiency of the delivered gene.</p

Kerr-Sen Black Hole as Accelerator for Spinning Particles

It has been proved that arbitrarily high-energy collision between two particles can occur near the horizon of an extremal Kerr black hole as long as the energy $E$ and angular momentum $L$ of one particle satisfies a critical relation, which is called the BSW mechanism. Previous researchers mainly concentrate on geodesic motion of particles. In this paper, we will take spinning particle which won't move along a timelike geodesic into our consideration, hence, another parameter $s$ describing the particle's spin angular momentum was introduced. By employing the Mathisson-Papapetrou-Dixon equation describing the movement of spinning particle, we will explore whether a Kerr-Sen black hole which is slightly different from Kerr black hole can be used to accelerate a spinning particle to arbitrarily high energy. We found that when one of the two colliding particles satisfies a critical relation between the energy $E$ and the total angular momentum $J$, or has a critical spinning angular momentum $s_c$, a divergence of the center-of-mass energy $E_{cm}$ will be obtained.Comment: Latex,17 pages,1 figure,minor revision,accepted by PR