The charge carrier localization in the cubic perovskite BaOsO3 revealed by an optical study.

We present the optical conductivity spectra for the newly discovered cubic perovskite structure BaOsO3 at various temperatures. The compound exhibits metallic behaviour above 50 K, but becomes non-metallic below 50 K. However, below 550 cm(-1), neither the typical Drude response nor an energy gap is observed in optical conductivity spectra from 300 K to 10 K. A broad peak centred at about 550 cm(-1) is observed in the real part of optical conductivity σ1(ω). The structure could be well reproduced by the localization modified Drude model. The life time of the carrier, deduced from σ1(ω) in terms of the localization modified Drude model, decreases with T varying from 300 K to 100 K, then increases slightly at 10 K. The study indicates that the compound is at the boundary of metal-insulator transition.

Structural phase transition in IrTe2: a combined study of optical spectroscopy and band structure calculations.

Ir(1-x)Pt(x)Te2 is an interesting system showing competing phenomenon between structural instability and superconductivity. Due to the large atomic numbers of Ir and Te, the spin-orbital coupling is expected to be strong in the system which may lead to nonconventional superconductivity. We grew single crystal samples of this system and investigated their electronic properties. In particular, we performed optical spectroscopic measurements, in combination with density function calculations, on the undoped compound IrTe2 in an effort to elucidate the origin of the structural phase transition at 280 K. The measurement revealed a dramatic reconstruction of band structure and a significant reduction of conducting carriers below the phase transition. We elaborate that the transition is not driven by the density wave type instability but caused by the crystal field effect which further splits/separates the energy levels of Te (p(x), p(y)) and Te p(z) bands.

Pharmacokinetics of azithromycin in serum and sinus fluid after administration of extended-release and immediate-release formulations in patients with acute bacterial sinusitis.

As high drug levels at the infection site are desirable for optimal activity, this study explored whether one dose of azithromycin extended release (AZ-ER) achieved higher azithromycin exposure in sinus fluid than azithromycin immediate release (AZ-IR) in adults with acute bacterial sinusitis. Subjects received AZ-ER (2g single dose; n=5) or AZ-IR (500mg daily for 3 days; n=4) and blood and sinus aspirates were collected until 120 h after initial dosing. Within 24 h, exposure was four- and three-fold higher with AZ-ER than with AZ-IR in serum and sinus fluid, respectively. Sinus fluid exposure was five- and three-fold higher than serum for AZ-IR and AZ-ER, respectively. Azithromycin concentrations in sinus fluid were maintained up to 120 h.

Comparative pharmacokinetics of voriconazole administered orally as either crushed or whole tablets.

Voriconazole is a triazole antifungal agent used to treat serious, invasive fungal infections including aspergillosis and candidemia. Limitations with existing formulations of voriconazole including restricted utility in patients with renal dysfunction (intravenous preparation) and the unavailability of an oral suspension in some countries make the administration of crushed tablets desirable in many clinical scenarios. However, concerns that this approach may alter the systemic absorption of voriconazole exist. Therefore, an open-label, randomized, two-way crossover comparative pharmacokinetic (PK) study using healthy volunteers was performed to compare these methods of tablet administration. In a random sequence, subjects received voriconazole tablets either crushed or whole. The voriconazole dose was 400 mg every 12 h for 1 day orally followed by 200 mg every 12 h orally for 5.5 days. Study periods were separated by 7 days. PK parameters were determined by the noncompartmental method. An equivalence approach with no-effect boundaries of 80 to 125% was used to assess bioequivalence. Twenty healthy subjects (10 males; aged 20 to 43 years) were enrolled in and completed the study. The adjusted mean areas under the plasma concentration-time curve from 0 to tau, where tau equals 12 h, for the crushed and whole tablet groups were 9,793 and 11,164 ng . h/ml, respectively (ratio, 87.72; 90% confidence interval [CI], 80.97, 95.04). The ratio of the maximum concentration of drug in serum for the crushed tablet versus whole tablet arms was 94.94 (90% CI, 86.51, 104.22). The only difference noted between groups was a slightly faster time to maximum concentration of drug in serum when subjects received crushed tablets, 0.5 h versus 1.5 h (90% CI, -0.75, -0.25). Treatment-related adverse events occurred in 12 subjects receiving whole tablets and 9 subjects receiving crushed tablets; all were mild. The administration of crushed voriconazole tablets is bioequivalent to whole-tablet administration.