Anharmonic phonon decay in cubic GaN

We present a Raman scattering study of optical phonons in zincblende (cubic) GaN for temperatures ranging from 80 to 750 K. The experiments were performed on high quality, cubic GaN films grown by molecular beamepitaxy on GaAs (001) substrates. The observed temperature dependence of the optical phonon frequencies and linewidths is analyzed in the framework of anharmonic decay theory, and possible decay channels are discussed in the light of density-functional theory calculations. The LO mode relaxation is found to occur via asymmetric decay into acoustic phonons, with an appreciable contribution of higher order processes. The TO mode linewidth shows a weak temperature dependence and its frequency downshift is primarily determined by the lattice thermal expansion. The LO phonon lifetime is derived from the observed Raman linewidth and an excellent agreement with previous theoretical predictions is foun

Derivation of induced pluripotent stem cells (iPSCs) by retroviral transduction of skin fibroblasts from four patients suffering 7q11.23 microduplication syndrome

Skin fibroblasts were obtained from four patients with 7q11.23 microduplication syndrome carrying the reciprocal rearrangement of Williams-Beuren syndrome at the 7q11.23 genomic region. Induced pluripotent stem cells (iPSCs) were generated by retroviral infection of fibroblasts with polycystronic vectors. The generated iPSC clones ESi058B, ESi057B, ESi070A and ESi071A had the 7q11.23 duplication with no additional genomic alterations, a stable karyotype, expressed pluripotency markers and could differentiate towards the three germ layers in vitro via embryoid body formation and in vivo by teratoma formation. Patient's derived iPSCs are a valuable resource for in vitro modeling of 7q11.23 microduplication syndrome

Genetic and epigenetic methylation defects and implication of the ERMN gene in autism spectrum disorders

Autism spectrum disorders (ASD) are highly heritable and genetically complex conditions. Although highly penetrant mutations in multiple genes have been identified, they account for the etiology of <1/3 of cases. There is also strong evidence for environmental contribution to ASD, which can be mediated by still poorly explored epigenetic modifications. We searched for methylation changes on blood DNA of 53 male ASD patients and 757 healthy controls using a methylomic array (450K Illumina), correlated the variants with transcriptional alterations in blood RNAseq data, and performed a case-control association study of the relevant findings in a larger cohort (394 cases and 500 controls). We found 700 differentially methylated CpGs, most of them hypomethylated in the ASD group (83.9%), with cis-acting expression changes at 7.6% of locations. Relevant findings included: (1) hypomethylation caused by rare genetic variants (meSNVs) at six loci (ERMN, USP24, METTL21C, PDE10A, STX16 and DBT) significantly associated with ASD (q-value <0.05); and (2) clustered epimutations associated to transcriptional changes in single-ASD patients (n = 4). All meSNVs and clustered epimutations were inherited from unaffected parents. Resequencing of the top candidate genes also revealed a significant load of deleterious mutations affecting ERMN in ASD compared with controls. Our data indicate that inherited methylation alterations detectable in blood DNA, due to either genetic or epigenetic defects, can affect gene expression and contribute to ASD susceptibility most likely in an additive manner, and implicate ERMN as a novel ASD gene

Electron effective mass and mobility in heavily doped n-GaAsN probed by Raman scattering

We investigate inelastic light scattering by longitudinal optic phonon-plasmon coupled modes LOPCMs in a series of heavily Se-doped, n-type GaAs1−xNx epilayers with x 0.4%. We perform a line shape analysis of the LOPCM spectra to estimate the optical effective mass, mopt , and the scattering time of the conduction electrons in GaAsN. We use these results to evaluate an effective carrier mobility for our samples. The values thus obtained, which we compare with measured electron Hall mobilities, indicate that the x-dependence of the mobility in GaAs1−xNx is dominated by the scattering time, rather than by the variation of the electron effective mass. The Raman analysis yields mopt values that are lower than those obtained from the band anticrossing model. © 2008 American Institute of Physics.This work is supported by the Spanish Government Projects MAT 2004-0664 and MAT2007-63617, and Ramon y Cajal Program and the EPSRC, United Kingdom. 1M. Henini, Dilute Nitride Semiconductors Elsevier Science, AmsterdamPeer reviewe

Surface acoustic wave velocity and elastic constants of cubic GaN

We present high-resolution surface Brillouin scattering measurements on cubic GaN layers grown on GaAs substrate. By using a suitable scattering geometry, scattering by surface acoustic waves is recorded for different azimuthal angles, and the surface acoustic wave velocities are determined. A comparison of experimental results with numerical simulations of the azimuthal dependence of the surface wave velocity shows good agreement and allows a consistent set of elastic constants for c-GaN to be determined

High-pressure lattice dynamics in wurtzite and rocksalt indium nitride investigated by means of Raman spectroscopy

We present an experimental and theoretical lattice-dynamical study of InN at high hydrostatic pressures. We perform Raman scattering measurements on five InN epilayers, with different residual strain and free electron concentrations. The experimental results are analyzed in terms of ab initio lattice-dynamical calculations on both wurtzite InN (w-InN) and rocksalt InN (rs-InN) as a function of pressure. Experimental and theoretical pressure coefficients of the optical modes in w-InN are compared, and the role of residual strain on the measured pressure coefficients is analyzed. In the case of the LO band, we analyze and discuss its pressure behavior considering the double-resonance mechanism responsible for the selective excitation of LO phonons with large wave vectors in w-InN. The pressure behavior of the L− coupled mode observed in a heavily doped n-type sample allows us to estimate the pressure dependence of the electron effective mass in w-InN. The results thus obtained are in good agreement with k⋅p theory. The wurtzite-to-rocksalt phase transition on the upstroke cycle and the rocksalt-to-wurtzite backtransition on the downstroke cycle are investigated, and the Raman spectra of both phases are interpreted in terms of DFT lattice-dynamical calculations. ©2013 American Physical SocietyWork was supported by the Spanish Ministerio de Economia y Competitividad through Projects MAT2010-16116, MAT2010-21270-C04-04 and MALTA Consolider Ingenio 2010 (CSD2007-00045).Ibánez, J.; Oliva, R.; Manjón Herrera, FJ.; Segura, A.; Yamaguchi, T.; Nanishi, Y.; Cuscó, R.... (2013). High-pressure lattice dynamics in wurtzite and rocksalt indium nitride investigated by means of Raman spectroscopy. Physical Review B. 88:115202-1-115202-13. https://doi.org/10.1103/PhysRevB.88.115202S115202-1115202-1388Wu, J. (2009). When group-III nitrides go infrared: New properties and perspectives. Journal of Applied Physics, 106(1), 011101. doi:10.1063/1.3155798Pinquier, C., Demangeot, F., Frandon, J., Pomeroy, J. W., Kuball, M., Hubel, H., … Gil, B. (2004). Raman scattering in hexagonal InN under high pressure. Physical Review B, 70(11). doi:10.1103/physrevb.70.113202Pinquier, C., Demangeot, F., Frandon, J., Chervin, J.-C., Polian, A., Couzinet, B., … Maleyre, B. (2006). Raman scattering study of wurtzite and rocksalt InN under high pressure. Physical Review B, 73(11). doi:10.1103/physrevb.73.115211Yao, L. D., Luo, S. D., Shen, X., You, S. J., Yang, L. X., Zhang, S. J., … Xie, S. S. (2010). Structural stability and Raman scattering of InN nanowires under high pressure. Journal of Materials Research, 25(12), 2330-2335. doi:10.1557/jmr.2010.0290Ibáñez, J., Manjón, F. J., Segura, A., Oliva, R., Cuscó, R., Vilaplana, R., … Artús, L. (2011). High-pressure Raman scattering in wurtzite indium nitride. Applied Physics Letters, 99(1), 011908. doi:10.1063/1.3609327Uehara, S., Masamoto, T., Onodera, A., Ueno, M., Shimomura, O., & Takemura, K. (1997). Equation of state of the rocksalt phase of III–V nitrides to 72 GPa or higher. Journal of Physics and Chemistry of Solids, 58(12), 2093-2099. doi:10.1016/s0022-3697(97)00150-9Duan, M.-Y., He, L., Xu, M., Xu, M.-Y., Xu, S., & Ostrikov, K. (Ken). (2010). Structural, electronic, and optical properties of wurtzite and rocksalt InN under pressure. Physical Review B, 81(3). doi:10.1103/physrevb.81.033102Davydov, V. Y., Klochikhin, A. A., Smirnov, A. N., Strashkova, I. Y., Krylov, A. S., Lu, H., … Gwo, S. (2009). Selective excitation ofE1(LO)andA1(LO)phonons with large wave vectors in the Raman spectra of hexagonal InN. Physical Review B, 80(8). doi:10.1103/physrevb.80.081204Cuscó, R., Ibáñez, J., Alarcón-Lladó, E., Artús, L., Yamaguchi, T., & Nanishi, Y. (2009). Raman scattering study of the long-wavelength longitudinal-optical-phonon–plasmon coupled modes in high-mobility InN layers. Physical Review B, 79(15). doi:10.1103/physrevb.79.155210Ernst, S., Goñi, A. R., Syassen, K., & Cardona, M. (1995). LO-Phonon-plasmon modes in n-GaAs and n-InP under pressure. Journal of Physics and Chemistry of Solids, 56(3-4), 567-570. doi:10.1016/0022-3697(94)00242-8Ernst, S., Goñi, A. R., Syassen, K., & Cardona, M. (1996). Plasmon Raman scattering and photoluminescence of heavily dopedn-type InP near the Γ-X crossover. Physical Review B, 53(3), 1287-1293. doi:10.1103/physrevb.53.1287Lin, Y. C., Chiu, C. H., Fan, W. C., Chia, C. H., Yang, S. L., Chuu, D. S., … Chou, W. C. (2007). Raman scattering of longitudinal-optical-phonon-plasmon coupling in Cl-doped ZnSe under high pressure. Journal of Applied Physics, 102(12), 123510. doi:10.1063/1.2826936Gonze, X., Beuken, J.-M., Caracas, R., Detraux, F., Fuchs, M., Rignanese, G.-M., … Allan, D. C. (2002). First-principles computation of material properties: the ABINIT software project. Computational Materials Science, 25(3), 478-492. doi:10.1016/s0927-0256(02)00325-7Goedecker, S., Teter, M., & Hutter, J. (1996). Separable dual-space Gaussian pseudopotentials. Physical Review B, 54(3), 1703-1710. doi:10.1103/physrevb.54.1703Troullier, N., & Martins, J. L. (1991). Efficient pseudopotentials for plane-wave calculations. Physical Review B, 43(3), 1993-2006. doi:10.1103/physrevb.43.1993Wu, M. F., Zhou, S. Q., Vantomme, A., Huang, Y., Wang, H., & Yang, H. (2006). High-precision determination of lattice constants and structural characterization of InN thin films. Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films, 24(2), 275-279. doi:10.1116/1.2167970Ueno, M., Yoshida, M., Onodera, A., Shimomura, O., & Takemura, K. (1994). Stability of the wurtzite-type structure under high pressure: GaN and InN. Physical Review B, 49(1), 14-21. doi:10.1103/physrevb.49.14Serrano, J., Bosak, A., Krisch, M., Manjón, F. J., Romero, A. H., Garro, N., … Kuball, M. (2011). InN Thin Film Lattice Dynamics by Grazing Incidence Inelastic X-Ray Scattering. Physical Review Letters, 106(20). doi:10.1103/physrevlett.106.205501Giannozzi, P., de Gironcoli, S., Pavone, P., & Baroni, S. (1991). Ab initiocalculation of phonon dispersions in semiconductors. Physical Review B, 43(9), 7231-7242. doi:10.1103/physrevb.43.7231Gonze, X., & Lee, C. (1997). Dynamical matrices, Born effective charges, dielectric permittivity tensors, and interatomic force constants from density-functional perturbation theory. Physical Review B, 55(16), 10355-10368. doi:10.1103/physrevb.55.10355Weinstein, B. A. (1977). Phonon dispersion of zinc chalcogenides under extreme pressure and the metallic transformation. Solid State Communications, 24(9), 595-598. doi:10.1016/0038-1098(77)90369-6Yakovenko, E. V., Gauthier, M., & Polian, A. (2004). High-pressure behavior of the bond-bending mode of AIN. Journal of Experimental and Theoretical Physics, 98(5), 981-985. doi:10.1134/1.1767565Ibáñez, J., Segura, A., García-Domene, B., Oliva, R., Manjón, F. J., Yamaguchi, T., … Artús, L. (2012). High-pressure optical absorption in InN: Electron density dependence in the wurtzite phase and reevaluation of the indirect band gap of rocksalt InN. Physical Review B, 86(3). doi:10.1103/physrevb.86.035210Serrano, J., Romero, A. H., Manjón, F. J., Lauck, R., Cardona, M., & Rubio, A. (2004). Pressure dependence of the lattice dynamics of ZnO: Anab initioapproach. Physical Review B, 69(9). doi:10.1103/physrevb.69.094306Cuscó, R., Ibáñez, J., Domenech-Amador, N., Artús, L., Zúñiga-Pérez, J., & Muñoz-Sanjosé, V. (2010). Raman scattering of cadmium oxide epilayers grown by metal-organic vapor phase epitaxy. Journal of Applied Physics, 107(6), 063519. doi:10.1063/1.3357377Cuscó, R., Alarcón-Lladó, E., Ibáñez, J., Yamaguchi, T., Nanishi, Y., & Artús, L. (2009). Raman scattering study of background electron density in InN: a hydrodynamical approach to the LO-phonon–plasmon coupled modes. Journal of Physics: Condensed Matter, 21(41), 415801. doi:10.1088/0953-8984/21/41/415801Cuscó, R., Ibáñez, J., Alarcón-Lladó, E., Artús, L., Yamaguchi, T., & Nanishi, Y. (2009). Photoexcited carriers and surface recombination velocity in InN epilayers: A Raman scattering study. Physical Review B, 80(15). doi:10.1103/physrevb.80.155204Wang, X., Che, S.-B., Ishitani, Y., & Yoshikawa, A. (2006). Experimental determination of strain-free Raman frequencies and deformation potentials for the E2 high and A1(LO) modes in hexagonal InN. Applied Physics Letters, 89(17), 171907. doi:10.1063/1.2364884Perlin, P., Jauberthie-Carillon, C., Itie, J. P., San Miguel, A., Grzegory, I., & Polian, A. (1992). Raman scattering and x-ray-absorption spectroscopy in gallium nitride under high pressure. Physical Review B, 45(1), 83-89. doi:10.1103/physrevb.45.83Perlin, P., Suski, T., Ager, J. W., Conti, G., Polian, A., Christensen, N. E., … Haller, E. E. (1999). Transverse effective charge and its pressure dependence in GaN single crystals. Physical Review B, 60(3), 1480-1483. doi:10.1103/physrevb.60.1480Halsall, M. P., Harmer, P., Parbrook, P. J., & Henley, S. J. (2004). Raman scattering and absorption study of the high-pressure wurtzite to rocksalt phase transition of GaN. Physical Review B, 69(23). doi:10.1103/physrevb.69.235207Goñi, A. R., Siegle, H., Syassen, K., Thomsen, C., & Wagner, J.-M. (2001). Effect of pressure on optical phonon modes and transverse effective charges inGaNandAlN. Physical Review B, 64(3). doi:10.1103/physrevb.64.035205Watson, G. H., Daniels, W. B., & Wang, C. S. (1981). Measurements of Raman intensities and pressure dependence of phonon frequencies in sapphire. Journal of Applied Physics, 52(2), 956-958. doi:10.1063/1.328785Manjón, F. J., Errandonea, D., Romero, A. H., Garro, N., Serrano, J., & Kuball, M. (2008). Lattice dynamics of wurtzite and rocksalt AlN under high pressure: Effect of compression on the crystal anisotropy of wurtzite-type semiconductors. Physical Review B, 77(20). doi:10.1103/physrevb.77.205204Domènech-Amador, N., Cuscó, R., Artús, L., Stoica, T., & Calarco, R. (2012). Longer InN phonon lifetimes in nanowires. Nanotechnology, 23(8), 085702. doi:10.1088/0957-4484/23/8/085702Gorczyca, I., Plesiewicz, J., Dmowski, L., Suski, T., Christensen, N. E., Svane, A., … Speck, J. S. (2008). Electronic structure and effective masses of InN under pressure. Journal of Applied Physics, 104(1), 013704. doi:10.1063/1.2953094Cardona, M., & Güntherodt, G. (Eds.). (1984). Light Scattering in Solids IV. Topics in Applied Physics. doi:10.1007/3-540-11942-6Artús, L., Cuscó, R., Ibáñez, J., Blanco, N., & González-Díaz, G. (1999). Raman scattering by LO phonon-plasmon coupled modes inn-type InP. Physical Review B, 60(8), 5456-5463. doi:10.1103/physrevb.60.5456Ib��ez, J., Cusc�, R., & Art�s, L. (2001). Raman Scattering Determination of Free Charge Density Using a Modified Hydrodynamical Model. physica status solidi (b), 223(3), 715-722. doi:10.1002/1521-3951(200102)223:33.0.co;2-oKasic, A., Schubert, M., Saito, Y., Nanishi, Y., & Wagner, G. (2002). Effective electron mass and phonon modes inn-type hexagonal InN. Physical Review B, 65(11). doi:10.1103/physrevb.65.115206Demangeot, F., Pinquier, C., Frandon, J., Gaio, M., Briot, O., Maleyre, B., … Gil, B. (2005). Raman scattering by the longitudinal optical phonon in InN: Wave-vector nonconserving mechanisms. Physical Review B, 71(10). doi:10.1103/physrevb.71.104305Thakur, J. S., Haddad, D., Naik, V. M., Naik, R., Auner, G. W., Lu, H., & Schaff, W. J. (2005). A1(LO)phonon structure in degenerate InN semiconductor films. 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Defective minor spliceosome mRNA processing results in isolated familial growth hormone deficiency

The molecular basis of a significant number of cases of isolated growth hormone deficiency remains unknown. We describe three sisters affected with severe isolated growth hormone deficiency and pituitary hypoplasia caused by biallelic mutations in the RNPC3 gene, which codes for a minor spliceosome protein required for U11/U12 small nuclear ribonucleoprotein (snRNP) formation and splicing of U12-type introns. We found anomalies in U11/U12 di-snRNP formation and in splicing of multiple U12-type introns in patient cells. Defective transcripts include preprohormone convertases SPCS2 and SPCS3 and actin-related ARPC5L genes, which are candidates for the somatotroph-restricted dysfunction. The reported novel mechanism for familial growth hormone deficiency demonstrates that general mRNA processing defects of the minor spliceosome can lead to very narrow tissue-specific consequences.Peer reviewe

Lemierre Syndrome associated with dental infections : report of one case and review of the literature

The first publication on Lemierre Syndrome appears in 1936 by Lemierre. It is defined as an ?oropharynx bacterial infection characterized by the thrombophlebitis in the internal jugular vein, derived in a systemic septic embolism?. In 81% of the cases, the Fusobacterium necrophorum is the most frequent etiologic agent. Fever is the most common symptom, but it can depending on the primary infection, tonsillitis, mastoiditis or odontogenic infection. According to the literature the mortality is very low, but with a significant morbidity, that is why the diagnosis and early treatment is very important. The diagnosis it´s clinical, even though the CT scan and other diagnosis methods (echography, MRI) help to determine the extent of the infection. It?s necessary to administrate the antibiotics endovenous at high dose, (keeping in mind that the most frequent micro organism is anaerobic), and vital support measures if neccessary. We present a case report of Lemierre Syndrome associated to an odonthogenic infection caused by the 4.8 molar

Whole genome sequencing and de novo assembly of Staphylococcus pseudintermedius: a pangenome approach to unravelling pathogenesis of canine pyoderma

Background Staphylococcus pseudintermedius is the main aetiological agent of canine pyoderma. Whole genome sequencing is the most comprehensive way of obtaining relevant genomic information about micro-organisms. Hypothesis/Objectives Oxford Nanopore technology enables quality sequencing and de novo assembly of the whole genome of S. pseudintermedius. Whole genome analysis of S. pseudintermedius may help to better understand the pathogenesis of canine pyodermas. Methods and materials Twenty-two strains of S. pseudintermedius isolated from the skin of five healthy dogs and 33 strains isolated from skin of 33 dogs with pyoderma were analysed. DNA was extracted and sequenced using Oxford Nanopore MinION, a new technology that delivers longer reads in a hand-held device. The pangenome was analysed and visualised with Anvi’o 6.1. Results Nanopore technology allowed the sequencing and de novo assembly of the genomes of 55 S. pseudintermedius strains isolated from healthy dogs and from dogs with pyoderma. The average genome size of S. pseudintermedius was 2.62 Mbp, with 48% being core genome. Pyoderma isolates contained a higher number of antimicrobial resistance genes, yet the total number of virulence factors genes did not change between isolates from healthy dogs and from dogs with pyoderma. Genomes of meticillin-resistant S. pseudintermedius (MRSP) strains were larger than those of meticillin-susceptible (MSSP) strains (2.80 Mbp versus 2.59 Mbp), as a consequence of a greater presence of antimicrobial resistance genes, phages and prophages. Conclusions and clinical importance This technique allows much more precise and easier characterisation of canine S. pseudintermedius populations and may lead to a better understanding of the pathogenesis of canine pyodermas.info:eu-repo/semantics/publishedVersio