Sturm-Liouville Problem for Stationary Differential Operator with Nonlocal Two-Point Boundary Conditions

The Sturm-Liouville problem with various types of two-point boundary conditions is considered in this paper. In the first part of the paper, we investigate the Sturm-Liouville problem in three cases of nonlocal two-point boundary conditions. We prove general properties of the eigenfunctions and eigenvalues for such a problem in the complex case. In the second part, we investigate the case of real eigenvalues. It is analyzed how the spectrum of these problems depends on the boundary condition parameters. Qualitative behavior of all eigenvalues subject to the nonlocal boundary condition parameters is described

Investigation of Negative Critical Points of the Characteristic Function for Problems with Nonlocal Boundary Conditions

In this paper the Sturm-Liouville problem with one classical and the other nonlocal two-point or integral boundary condition is investigated. Critical points of the characteristic function are analyzed. We investigate how distribution of the critical points depends on nonlocal boundary condition parameters. In the first part of this paper we investigate the case of negative critical points

New carbazole-indan-1,3-dione- based host materials for phosphorescent organic light emitting diodes

New carbazole- and indan-1,3-dione -based low molecular weight derivatives were synthesized and characterized by mass spectrometry and 1H NMR spectroscopy. Thermal behaviour of the derivatives was demonstrated by thermo-gravimetric analysis and differential scanning calorimetry. The materials were found to show very high thermal stability having initial thermal degradation temperatures in the range of 398- 401°C. Glass transition temperatures of the amorphous molecular materials were in the rage of 80–114°C. The derivatives were tested as host materials in blue phosphorescent organic light emitting diodes with iridium(III)[bis(4,6-difluorophenyl)- pyridinato-N,C2 ]picolinate as the guests. One of the blue OLED devices demonstrated rather low turn-on voltage of 5.0 V, a maximum luminance efficiency of 2.73 cd/A and maximum brightness of about 220 cd/m2Kauno technologijos universitetasVytauto Didžiojo universitetasŽemės ūkio akademij