Anomalous pressure behavior of tangential modes in single-wall carbon nanotubes

Using the molecular dynamics simulations and the force constant model we have studied the Raman-active tangential modes (TMs) of a (10, 0) single-wall carbon nanotube (SWNT) under hydrostatic pressure. With increasing pressure, the atomic motions in the three TMs present obvious diversities. The pressure derivative of E1g, A1g, and E2g mode frequency shows an increased value (), a constant value (), and a negative value () above 5.3 GPa, respectively. The intrinsic characteristics of TMs consumedly help to understand the essence of the experimental T band of CNT. The anomalous pressure behavior of the TMs frequencies may be originated from the tube symmetry alteration from D10h to D2h then to C2h.Comment: 15 pages, 3 pages, submitted to Phys. Rev.

Phylogeographic analyses of an epiphytic foliose lichen show multiple dispersal events westward from the Hengduan Mountains of Yunnan into the Himalayas.

Lobaria pindarensis is an endemic species of the Himalayas and the Hengduan Mountains. Little information is available on the phylogeography genetics and colonization history of this species or how its distribution patterns changed in response to the orographic history of the Himalayas and Hengduan Mountains. Based on samples covering a major part of the species' distribution range, we used 443 newly generated sequences of nine loci for molecular coalescent analyses in order to reconstruct the evolutionary history of L. pindarensis, and to reconstruct the species' ancestral phylogeographic distributions using Bayesian binary MCMC analyses. The results suggest that current populations originated from the Yunnan region of the Hengduan Mountains in the middle Pliocene, and that the Himalayas of Bhutan were colonized by a lineage that diverged from Yunnan ca. 2.72 Ma. The analysis additionally indicates that the Nepal and Xizang areas of the Himalayas were colonized from Yunnan as well, and that there was later a second dispersal event from Yunnan to Bhutan. We conclude that the change in climate and habitat related to the continuous uplift of the Himalayas and the Hengduan Mountains in the late Pliocene and middle Pleistocene influenced the geographic distribution pattern of L. pindarensis

Tris(ethyl­enediammonium) bis­[(2-amino­ethyl)ammonium] bis­[bis­(μ5-hydrogen phosphato)penta-μ2-oxido-deca­oxido­penta­molybdenum(VI)] deca­hydrate

The title compound, (C2H10N2)3(C2H9N2)2[Mo5(HPO4)2O15]·10H2O, was prepared under hydro­thermal conditions at pH 5.0. The structure contains mono- and diprotonated ethyl­enediamine cations, [Mo5O15(HPO4)2]4− anions and uncoord­in­ated water mol­ecules. The [Mo5O15(HPO4)2]4− hetero­poly­oxometallate anion is made up of five MoO6 octa­hedra sharing an edge and forming a ring, which is closed by common corners of the terminal MoO6 octa­hedron. The ring is topped on both sides by two slightly distorted PO4 tetra­hedra, sharing three corners with three MoO6 octa­hedra. The terminal oxygen atoms of the PO4 units are protonated. Together with the anions, the water mol­ecules and the ethyl­enediammonium cations are involved in N—H⋯O and O—H⋯O hydrogen bonding, forming a three-dimensional supra­molecular network