Vibrational properties of SrVO2 H with large spin-phonon coupling

The antiferromagnetic transition metal oxyhydride SrVO2H is distinguished by its stoichiometric composition and an ordered arrangement of H atoms. The tetragonal structure is related to the cubic perovskite and consists of alternating layers of VO2 and SrH. d2 V(III) attains a sixfold coordination by four O and two H atoms. The latter are arranged in a trans fashion, which produces H-V-H chains along the tetragonal axis. Here, we investigate the vibrational properties of SrVO2H by inelastic neutron scattering and infrared spectroscopy combined with phonon calculations based on density functional theory. The H-based vibrational modes divide into a degenerate bending motion perpendicular to the H-V-H chain direction and a highly dispersed stretching motion along the H-V-H chain direction. The bending motion, with a vibrational frequency of approximately 800 cm-1, is split into two components separated by about 50 cm-1, owing to the doubled unit cell from the antiferromagnetic structure. Interestingly, spin-phonon coupling stiffens the H-based modes by 50-100cm-1 although super-exchange coupling via H is very small. Frequency shifts of the same order of magnitude also occur for V-O modes. It is inferred that SrVO2H displays the hitherto largest recognized coupling between magnetism and phonons in a material

Correction: Multigene Assessment of the Species Boundaries and Sexual Status of the Basidiomycetous Yeasts Cryptococcus flavescens and C. terrestris (Tremellales).

This work was supported by funds from FCT-Fundacao para a Ciencia e a Tecnologia, Portugal (www.fct.pt), project PTDC/BIA-MIC/113051/2009. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Cryptococcus flavescens and C. terrestris are phenotypically indistinguishable sister species that belong to the order Tremellales (Tremellomycetes, Basidiomycota) and which may be mistaken for C. laurentii based on phenotype. Phylogenetic separation between C. flavescens and C. terrestris was based on rDNA sequence analyses, but very little is known on their intraspecific genetic variability or propensity for sexual reproduction. We studied 59 strains from different substrates and geographic locations, and used a multilocus sequencing (MLS) approach complemented with the sequencing of mating type (MAT) genes to assess genetic variation and reexamine the boundaries of the two species, as well as their sexual status. The following five loci were chosen for MLS: the rDNA ITS-LSU region, the rDNA IGS1 spacer, and fragments of the genes encoding the largest subunit of RNA polymerase II (RPB1), the translation elongation factor 1 alpha (TEF1) and the p21-activated protein kinase (STE20). Phylogenetic network analyses confirmed the genetic separation of the two species and revealed two additional cryptic species, for which the names Cryptococcus baii and C. ruineniae are proposed. Further analyses of the data revealed a high degree of genetic heterogeneity within C. flavescens as well as evidence for recombination between lineages detected for this species. Strains of C. terrestris displayed higher levels of similarity in all analysed genes and appear to make up a single recombining group. The two MAT genes (STE3 and SXI1/SXI2) sequenced for C. flavescens strains confirmed the potential for sexual reproduction and suggest the presence of a tetrapolar mating system with a biallelic pheromone/receptor locus and a multiallelic HD locus. In C. terrestris we could only sequence STE3, which revealed a biallelic P/R locus. In spite of the strong evidence for sexual recombination in the two species, attempts at mating compatible strains of both species on culture media were unsuccessful.publishersversionpublishe

Custom designed dynamic videokeratometer

The human eye is a complex dynamic system that undergoes fine rotations and deformations. Usually information about the eye globe deformation and micromovements are averaged and lost when using commercial measuring devices, although they provide important information about the eye’s physiology and the visual process. We have constructed a dynamic topographer from an existing Placido projection head and a video camera. The algorithms of calibration, data processing and topographic reconstruction are also explained in this paper. With our system, the CCD parameters and the algorithms can be controlled offering many possibilities for eye researchers. Obtained results show that the system is reliable for measuring eye dynamics. Some applications of the device are also outlined.This work has been partially supported by the Spanish Ministry of Education and Science through the project no. FIS2005-05053. H. Kasprzak acknowledges the University of Alicante its economical support through the project Senior 08/07. D. Mas acknowledges the support of the Generalitat Valenciana through the project BEST-2008-148

Phylogenetic trees based on (A) partial <i>STE3</i> nucleotide sequences of <i>Cryptococcus flavescens</i> and <i>C</i>. <i>terrestris</i>, (B) partial <i>SXI2</i> nucleotide sequences of <i>Cryptococcus flavescens</i>, and (C) different mating types of <i>Cryptococcus flavescens</i> inferred from the analysis of the P/R (A) and HD (B) loci.

<p>The numbers given on branches are frequencies (>70%) with which a given branch appeared in 1,000 bootstrap replications. The scale indicates the number of expected substitutions accumulated per site. Accession numbers of nucleotide sequences are provided in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120400#pone.0120400.s007" target="_blank">S1 Table</a>.</p

Schematic representation of <i>Cryptococcus flavescens</i> gene cluster organization of (A) <i>MAT</i> A2 inferred based on the NRRL Y-50378 genome sequence; (B) <i>MAT</i> A1 gene organization predicted based on PCR-approaches (dashed arrows); and (C) HD locus inferred based on the NRRL Y-50378 genome sequence.

<p>Schematic representation of <i>Cryptococcus flavescens</i> gene cluster organization of (A) <i>MAT</i> A2 inferred based on the NRRL Y-50378 genome sequence; (B) <i>MAT</i> A1 gene organization predicted based on PCR-approaches (dashed arrows); and (C) HD locus inferred based on the NRRL Y-50378 genome sequence.</p