112 research outputs found
CHARACTERIZATION OF LABELED PROGENITOR DERIVED ENDOTHELIAL CELLS FOR TISSUE ENGINEERING APPLICATIONS
Oral Communication presented at the ";Forum des Jeunes Chercheurs";, Brest (France) 2011
Slater to Mott crossover in the metal to insulator transition of Nd2Ir2O7
We present an angle-resolved photoemission study of the electronic structure
of the three-dimensional pyrochlore iridate Nd2Ir2O7 through its magnetic
metal-insulator transition. Our data reveal that metallic Nd2Ir2O7 has a
quadratic band, touching the Fermi level at the Gamma point, similarly to that
of Pr2Ir2O7. The Fermi node state is, therefore, a common feature of the
metallic phase of the pyrochlore iridates. Upon cooling below the transition
temperature, this compound exhibits a gap opening with an energy shift of
quasiparticle peaks like a band gap insulator. The quasiparticle peaks are
strongly suppressed, however, with further decrease of temperature, and
eventually vanish at the lowest temperature, leaving a non-dispersive flat band
lacking long-lived electrons. We thereby identify a remarkable crossover from
Slater to Mott insulators with decreasing temperature. These observations
explain the puzzling absence of Weyl points in this material, despite its
proximity to the zero temperature metal-insulator transition
Treating clinical mastitis in dairy cows with essential oils
Clinical mastitis is the main concern in dairy farming today, but there are very few drugs that are compatible with organic specifications. Our study was conducted in order to evaluate the therapeutic efficiency of the intramammary infusion of three essential oils, Thymus vulgaris, Rosmarinus verbenone and Laurus nobilis. Fifty-five cases of mastitis were treated with 10 ml of a mixture of the three oils (1.5% each in sunflower oil). Forty-five others were treated with 10 ml of a mixture of Thymus vulgaris and Rosmarinus verbenone (6% of each in sunflower oil or in water). The recovery rate was only 40%, which is deemed unsatisfactory
Early lean mass sparing effect of high-protein diet with excess leucine during long-term bed rest in women
Muscle inactivity leads to muscle atrophy. Leucine is known to inhibit protein degradation and to promote protein synthesis in skeletal muscle. We tested the ability of a high-protein diet enriched with branched-chain amino acids (BCAAs) to prevent muscle atrophy during long-term bed rest (BR). We determined body composition (using dual energy x-ray absorptiometry) at baseline and every 2-weeks during 60 days of BR in 16 healthy young women. Nitrogen (N) balance was assessed daily as the difference between N intake and N urinary excretion. The subjects were randomized into two groups: one received a conventional diet (1.1 ± 0.03 g protein/kg, 4.9 ± 0.3 g leucine per day) and the other a high protein, BCAA-enriched regimen (1.6 ± 0.03 g protein-amino acid/kg, 11.4 ± 0.6 g leucine per day). There were significant BR and BR × diet interaction effects on changes in lean body mass (LBM) and N balance throughout the experimental period (repeated measures ANCOVA). During the first 15 days of BR, lean mass decreased by 4.1 ± 0.9 and 2.4 ± 2.1% (p < 0.05) in the conventional and high protein-BCAA diet groups, respectively, while at the end of the 60-day BR, LBM decreased similarly in the two groups by 7.4 ± 0.7 and 6.8 ± 2.4%. During the first 15 days of BR, mean N balance was 2.5 times greater (p < 0.05) in subjects on the high protein-BCAA diet than in those on the conventional diet, while we did not find significant differences during the following time intervals. In conclusion, during 60 days of BR in females, a high protein-BCAA diet was associated with an early protein-LBM sparing effect, which ceased in the medium and long term
Giant spin splitting of the two-dimensional electron gas at the surface of SrTiO3
Two-dimensional electron gases (2DEGs) forming at the interfaces of transition metal oxides(1-3) exhibit a range of properties, including tunable insulator-superconductor-metal transitions(4-6), large magnetoresistance(7), coexisting ferromagnetism and superconductivity(8,9), and a spin splitting of a few meV (refs 10,11). Strontium titanate (SrTiO3), the cornerstone of such oxide-based electronics, is a transparent, non-magnetic, wide-bandgap insulator in the bulk, and has recently been found to host a surface 2DEG (refs 12-15). The most strongly confined carriers within this 2DEG comprise two subbands, separated by an energy gap of 90 meV and forming concentric circular Fermi surfaces(12,13,15). Using spin-and angle-resolved photoemission spectroscopy (SARPES), we show that the electron spins in these subbands have opposite chiralities. Although the Rashba effect might be expected to give rise to such spin textures, the giant splitting of almost 100 meV at the Fermi level is far larger than anticipated(16,17). Moreover, in contrast to a simple Rashba system, the spin-polarized subbands are non-degenerate at the Brillouin zone centre. This degeneracy can be lifted by time-reversal symmetry breaking, implying the possible existence of magnetic order. These results show that confined electronic states at oxide surfaces can be endowed with novel, non-trivial properties that are both theoretically challenging to anticipate and promising for technological applications
Devil's staircase transition of the electronic structures in CeSb
Solids with competing interactions often undergo complex phase transitions
with a variety of long-periodic modulations. Among such transition, devil's
staircase is the most complex phenomenon, and for it, CeSb is the most famous
material, where a number of the distinct phases with long-periodic
magnetostructures sequentially appear below the Neel temperature. An evolution
of the low-energy electronic structure going through the devil's staircase is
of special interest, which has, however, been elusive so far despite the
40-years of intense researches. Here we use bulk-sensitive angle-resolved
photoemission spectroscopy and reveal the devil's staircase transition of the
electronic structures. The magnetic reconstruction dramatically alters the band
dispersions at each transition. We moreover find that the well-defined band
picture largely collapses around the Fermi energy under the long-periodic
modulation of the transitional phase, while it recovers at the transition into
the lowest-temperature ground state. Our data provide the first direct evidence
for a significant reorganization of the electronic structures and spectral
functions occurring during the devil's staircase.Comment: 22 pages, 5 figure
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