Oxygen-vacancy-mediated Negative Differential Resistance in La and Mg co-substituted BiFeO3 Thin Film

The conductive characteristics of Bi0.9La0.1Fe0.96Mg0.04O3(BLFM) thin film are investigated at various temperatures and a negative differential resistance (NDR) is observed in the thin film, where a leakage current peak occurs upon application of a downward electric field above 80 oC. The origin of the NDR behavior is shown to be related to the ionic defect of oxygen vacancies (VO..) present in the film. On the basis of analyzing the leakage mechanism and surface potential behavior, the NDR behavior can be understood by considering the competition between the polarized distribution and neutralization of VO..

A class of multilevel parallel preconditioning strategies

In this paper, we introduce a class of recursive multilevel preconditioning strategies suited for solving large sparse linear systems of equations on modern day architectures. They are based on a reordering of the input matrix into a nested bordered block diagonal form, which allows a nested formulation of the preconditioners. The first one, which we refer to as nested SSOR (NSSOR), requires only the factorization of diagonal blocks at the innermost level of the recursive formulation. Hence, its construction is embarassingly parallel, and the memory requirements are very limited. Next two are nested versions of Modified ILU preconditioner with row sum (NMILUR) and colsum (NMILUC) property. We compare these methods in terms of iteration number, memory requirements, and overall solve time, with ILU(0) with natural ordering and nested dissection ordering, and MILU. We find that NSSOR compares favorably with ILU(0) with nested dissection ordering, while NMILUR and NMILUC outperform the other methods for certain matrices in our test set. It is proved that the NSSOR method is convergent when the input matrix is SPD. The preconditioners are designed to be suitable for parallel computing.Dans ce papier nous décrivons une classe de préconditionneurs multiniveaux parallèles pour résoudre des systèmes linéaires de grande taille. Ils se basent sur une renumérotation de la matrice d'entrée en forme block diagonale bornée et emboitée, qui permet une définition emboitée des préconditionneurs. Nous prouvons qu'un des préconditionneurs, NSSOR, converge quand la matrice d'entrée est symmétrique et définie positive. Les préconditionneurs sont adaptés au calcul parallèle

BIOANALYTICAL METHOD DEVELOPMENT AND VALIDATION OF ENTRECTINIB IN RAT PLASMA BY LIQUID CHROMATOGRAPHY–TANDEM MASS SPECTROMETRY

Objective: The objective of the study was to develop and validate the bioanalytical liquid chromatography–mass spectrometry (LCMS/MS) method for the estimation of entrectinib in bulk and pharmaceutical drugs in rat plasma. Methods: Chromatographic separation of entrectinib with D4-entrectinib as internal standard (IS) was achieved using Waters Alliance high-performance liquid chromatography system, quaternary gradient pump of e2695, using Luna, 250×4.6 mm, 5 μm column and the mobile phase containing 0.1% formic acid and acetonitrile (ACN) within the ratio of 70:30% v/v. The flow was 1.0 ml/min; detection was carried out by absorption at 294 nm using a photodiode array detector at ambient temperature. Results: The peak of entrectinib was eluted at retention times of 5.225 min. The multiple reaction monitoring was 560.6/475.1 (m/z) for entrectinib and 580.6/496.3 (m/z) for IS entrectinib (D4). The linearity range was 1–20 ng/ml with a regression coefficient of 0.999. % relative standard deviation of peak areas of all measurements always <2.0. Conclusion: The method was successfully validated and it had been found to be within limits for accuracy, precision, and linearity and it is stable under analytical conditions used

Origin of the Enhanced Polarization in La and Mg Co-substituted BiFeO3 Thin Film during the Fatigue Process

We have studied the polarization fatigue of La and Mg co-substituted BiFeO3 thin film, where a polarization peak is observed during the fatigue process. The origin of such anomalous behavior is analyzed on the basis of the defect evolution using temperature-dependent impedance spectroscopy. It shows that the motion of oxygen vacancies (VO..) is associated with a lower energy barrier, accompanied by the injection of electrons into the film during the fatigue process. A qualitative model is proposed to explain the fatigue behavior, which involves the modification of the Schottky barrier upon the accumulation of VO.. at the metal-dielectric interface