Electrical Conductivity and Dielectric Properties of Bi4_{4}Ti3_{3}O12_{12}

The present paper deals with the investigation of electrical and dielectric properties of structures based on Bi$_{4}$Ti$_{3}$O$_{12}$ films. It has been found that the nonlinearity of the $I - U$ characteristics in Me-Bi$_{4}$Ti$_{3}$O$_{12}$-Me structures is attributed to intercrystalline potential barriers. The height of the intercrystalline barrier ($\Phi_{0}=0.12$ eV) and the mean size of crystallise ($L=0.3~\mu$m) have been determined. At rather low temperatures, the hopping conductivity with a mean length of hopping, $\sim 2.6 \times 10^{19}$ cm$^{-3}$ eV$^{-1}$, is shown to be a dominant process at the charge transfer. It has been found that the electrical conductivity ($\sigma$) in the direction parallel to the $C$-axis (“sandwich” configuration) shows an anomaly in the phase transition region ($\sim 950$ K), while in the direction perpendicular to the $C$-axis, a simple bending of $\sigma$ vs. $T$ is observed. The latter is explained by the change of spontaneous polarization in Bi$_{4}$Ti$_{3}$O$_{12}$ films. The temperature dependence of the dielectric constant and the dielectric loss tangent have the maxima in the range of the phase transition temperature. The dielectric constant values are $\sim 650 \sim 120$ for the structures of “sandwich” and planar configurations, respectively. This fact indicates the presence of a polarization component in the given direction. The diffusion of the phase transition is explained by the imperfection of the film structure

Mortality from esophagectomy for esophageal cancer across low, middle, and high-income countries: An international cohort study.

BACKGROUND No evidence currently exists characterising global outcomes following major cancer surgery, including esophageal cancer. Therefore, this study aimed to characterise impact of high income countries (HIC) versus low and middle income countries (LMIC) on the outcomes following esophagectomy for esophageal cancer. METHOD This international multi-center prospective study across 137 hospitals in 41 countries included patients who underwent an esophagectomy for esophageal cancer, with 90-day follow-up. The main explanatory variable was country income, defined according to the World Bank Data classification. The primary outcome was 90-day postoperative mortality, and secondary outcomes were composite leaks (anastomotic leak or conduit necrosis) and major complications (Clavien-Dindo Grade III - V). Multivariable generalized estimating equation models were used to produce adjusted odds ratios (ORs) and 95% confidence intervals (CI). RESULTS Between April 2018 to December 2018, 2247 patients were included. Patients from HIC were more significantly older, with higher ASA grade, and more advanced tumors. Patients from LMIC had almost three-fold increase in 90-day mortality, compared to HIC (9.4% vs 3.7%, p < 0.001). On adjusted analysis, LMIC were independently associated with higher 90-day mortality (OR: 2.31, CI: 1.17-4.55, p = 0.015). However, LMIC were not independently associated with higher rates of anastomotic leaks (OR: 1.06, CI: 0.57-1.99, p = 0.9) or major complications (OR: 0.85, CI: 0.54-1.32, p = 0.5), compared to HIC. CONCLUSION Resections in LMIC were independently associated with higher 90-day postoperative mortality, likely reflecting a failure to rescue of these patients following esophagectomy, despite similar composite anastomotic leaks and major complication rates to HIC. These findings warrant further research, to identify potential issues and solutions to improve global outcomes following esophagectomy for cancer