The evolution of octahedral rotations of orthorhombic LaVO3 in superlattices with cubic SrVO3

We have studied the octahedral rotations in LaVO3 SrVO3 superlattices, keeping the thickness of the orthorhombic LaVO3 layers constant and increasing the thickness of cubic SrVO3 layers. We have found that for a small thickness of SrVO3, the octahedral rotations in LaVO3 are maintained, while for an increasing thickness, these rotations are suppressed. This observation cannot be explained by purely elastic effects due to the lattice mismatch between the two materials, but the absence of rotations in SrVO3 is a crucial ingredient, illustrating the concept of interface engineering of octahedral rotation

Type-II Superconductivity in Ternary Zirconium Pnictide Chalcogenide Single Crystals

Layered Pnictides are proven to be a great reservoir for superconductors in the past and ternary zirconium pnictide chalcogenides of ZrXY-type (X = P, As; Y = S, Se) might be a platform for new superconductors. The superconducting properties of carefully grown (chemical transport reaction) single crystals of ZrP1.54S0.46 with a transition temperature of Tc = 3.5 K are investigated. This compound (PbFCl structure type) contains square planar nets: One of the nets is completely occupied (no vacancies) by P, the other one characterized by a random distribution of P and S (full occupation: no vacancies). Besides zero-field-cooling (zfc), field-cooling (fc), and remanent moment (rem) measurements, especially magnetization and ac susceptibility measurements are performed. A nearly ideal type-II behavior with a Ginzburg-Landau parameter κ = 24 is found. The magnetization curves between Bc1 and Bc2 for increasing field are in excellent agreement with theoretical calculations performed by E. H. Brandt based on the Ginzburg-Landau theory. The decreasing branches of the magnetization curves are asymmetric about the field axis indicating weak pinning and also large diamagnetic behavior

Estudio farmacocinético de propofol en equinos

Se estudian las características farmacocinéticas de propofol en 6 caballos. Se determinaron parámetros farmacocinéticos de propofol cuantificando sus concentraciones sanguíneas en función del tiempo por HPLC, tras su administración de 2.4 mg/kg por vía endovenosa al grupo de animales. Los datos de concentración se interpretaron por un modelo abierto de 2 compartimentos, obteniéndose, entre otros, los valores de t1/2a, t1/2b,Vdc, Vdss, Vdb, Cltotaly MRT. Las variables farmacodinámicas se encuentran acordes a la disposición cinética de este fármaco. El análisisde los parámetros farmacocinéticos del propofol indica que éste posee una rápida y pronta distribución a los tejidos y una rápida eliminación del organismo. El propofol se presenta como una alternativa anestésica factible de ser incorporada dentro de un protocolo anestésico en caballos. Los parámetros farmacocinéticos obtenidos contribuyen para una correcta dosificación ya sea para mantener un estado de anestesia por infusión continua o por inyecciones repetidasPharmacokinetic variables of propofol were studied in 6 horses. Blood concentration of propofol at different times, after a single dose of 2.4mg/kg bw, was determined by HPLC. An open two compartment model was used to evaluate blood concentrations of propofol. Values of t1/2a,t1/2b, Vdc, Vdss,Vdb, Cltotal y MRT were obtained.The pharmacodynamic values show a narrow relationship with the pharmacokinetic disposition of this drug. Propofol s pharmacokinetic disposition presented a rapid distribution and removal from organic tissues. It is concluded that propofol is an alternative to be considered in anaesthetic protocolsin horses, and the pharmacokinetic variables presented contribute to determinethe appropriate dose to be give

Low-energy excitations of a linearly Jahn-Teller coupled orbital quintet

The low-energy spectra of the single-mode h x (G+H) linear Jahn-Teller model is studied by means of exact diagonalization. Both eigenenergies and photoemission spectral intensities are computed. These spectra are useful to understand the vibronic dynamics of icosahedral clusters with partly filled orbital quintet molecular shells, for example C60 positive ions.Comment: 14 pages revte

Vacuum Polarization and the Electric Charge of the Positron

We show that higher-order vacuum polarization would contribute a measureable net charge to atoms, if the charges of electrons and positrons do not balance precisely. We obtain the limit $|Q_e+Q_{\bar e}| < 10^{-18} e$ for the sum of the charges of electron and positron. This also constitutes a new bound on certain violations of PCT invariance.Comment: 9 pages, 1 figure attached as PostScript file, DUKE-TH-92-38. Revised versio