Investigating the electrical crosstalk effect between pixels in high-resolution organic light-emitting diode microdisplays.

Organic light-emitting diode (OLED) microdisplays have received great attention owing to their excellent performance for augmented reality/virtual reality devices applications. However, high pixel density of OLED microdisplay causes electrical crosstalk, resulting in color distortion. This study investigated the current crosstalk ratio and changes in the color gamut caused by electrical crosstalk between sub-pixels in high-resolution full-color OLED microdisplays. A pixel structure of 3147 pixels per inch (PPI) with four sub-pixels and a single-stack white OLED with red, green, and blue color filters were used for the electrical crosstalk simulation. The results showed that the sheet resistance of the top and bottom electrodes of OLEDs rarely affected the electrical crosstalk. However, the current crosstalk ratio increased dramatically and the color gamut decreased as the sheet resistance of the common organic layer decreased. Furthermore, the color gamut of the OLED microdisplay decreased as the pixel density of the panel increased from 200 to 5000 PPI. Additionally, we fabricated a sub-pixel circuit to measure the electrical crosstalk current using a 3147 PPI scale multi-finger-type pixel structure and compared it with the simulation result.

Color gamut change by optical crosstalk in high-resolution organic light-emitting diode microdisplays.

Herein, the color gamut change by optical crosstalk between sub-pixels in high-resolution full-color organic light-emitting diode (OLED) microdisplays was numerically investigated. The color gamut of the OLED microdisplay decreased dramatically as the pixel density of the panel increased from 100 pixels per inch (PPI) to 3000 PPI. In addition, the increase in thickness of the passivation layer between the bottom electrode and the top color filter results in a decrease in the color gamut. We also calculated the color gamut change depending on the pixel structures in the practical OLED microdisplay panel, which had an aspect ratio of 32:9 and a pixel density of 2,490 PPI. The fence angle and height, refractive index of the passivation layer, black matrix width, and white OLED device structure affect the color gamut of the OLED microdisplay panel because of the optical crosstalk effect.

Synthesis, biological evaluation and molecular modelling of 2,4-disubstituted-5-(6-alkylpyridin-2-yl)-1H-imidazoles as ALK5 inhibitors.

A series of 2,4-disubstituted-5-(6-alkylpyridin-2-yl)-1H-imidazoles, 7a-c, 11a-h, and 16a-h has been synthesised and evaluated for their ALK5 inhibitory activity in an enzyme assay and in a cell-based luciferase reporter assay. Incorporation of a quinoxalin-6-yl moiety and a methylene linker at the 4- and 2-position of the imidazole ring, respectively, and a m-CONH2 substituent in the phenyl ring generated a highly potent and selective ALK5 inhibitor 11e. Docking model of ALK5 in complex with 11e showed that it fitted well in the ATP-binding pocket with favourable interactions.

Protocatechuic Acid Enhances Osteogenesis, but Inhibits Adipogenesis in C3H10T1/2 and 3T3-L1 Cells.

Abnormal activation of adipogenesis in mesenchymal stem cells (MSCs) and preadipocyte cells is associated with human metabolic disorders, such as osteoporosis and obesity. This study investigated the biological effects of protocatechuic acid (PCA) on the modulation of osteogenesis and adipogenesis in cultured cells. PCA stimulation of MSCs significantly increased intracellular mineralization during osteogenesis, but reduced lipid accumulation in both MSCs and 3T3-L1 preadipocyte cells during adipogenesis. Reverse transcription-polymerase chain reaction and immunoblotting analyses showed a dose-dependent upregulation of proosteogenic runt-related transcription factor 2 due to induction of ß-catenin. PCA reduced the expression of proadipogenic transcription factor, peroxisome proliferator-activated receptor-γ, and suppressed its promotor activity. These results suggest PCA exerts stimulatory effects on the osteogenesis of MSCs and inhibitory effects on the adipogenesis of MSCs and 3T3-L1 cells. PCA may contribute to maintain a coordinated metabolic balance between adipogenesis and osteogenesis, and thus may be useful for the prevention and alleviation of osteoporosis and obesity.

Synthesis and biological evaluation of 5-(pyridin-2-yl)thiazoles as transforming growth factor-beta type1 receptor kinase inhibitors.

A series of 5-(pyridin-2-yl)thiazoles (14a-l and 15a-l) has been synthesized and evaluated for their ALK5 inhibitory activity in cell-based luciferase reporter assays. Among them, 3-[[5-(6-methylpyridin-2-yl)-4-(quinoxalin-6-yl)thiazol-2-ylamino]methyl]benzamide (15i) and 3-[[5-(6-ethylpyridin-2-yl)-4-(quinoxalin-6-yl)thiazol-2-ylamino]methyl]benzamide (15k) showed more than 95% inhibition at 0.1 microM in luciferase reporter assays using HaCaT cells transiently transfected with p3TP-luc reporter construct and ARE-luciferase reporter construct.

Reversible control of assembly and disassembly of interlocked supermolecules.

Two kinds of interlocked supramolecular complexes that display stimulus-responsive assembly and disassembly have been described. One is a pseudorotaxane driven by hydrogen-bonding interactions between rings 2a and 2b and rods 1a and 1b. The rods contain a binding site for the ring as well as a stimulus-responsive diazo group, both of which are conformationally constrained in parallel by connecting them to a rigid xanthene skeleton. The trans isomer of 1a bearing a rigid binding site cannot form the pseudorotaxanes with the rings 2a and 2b because the neighboring diazophenyl group sterically shields the binding site. However, when trans-1a was converted to the corresponding cis-1a by UV light, the pseudorotaxanes are immediately formed with association constants of 70 +/- 10 M(-1) and (1.1 +/- 0.1) x 10(3) M(-1) for 2a and 2b, respectively, in CDCl3 at 24 +/- 1 degrees C. The pseudorotaxanes are completely disassembled into their molecular component when heated at 80-85 degrees C for 20 min. The assembly and disassembly processes can be reversibly cycled by repeating irradiation and heating alternatively. In the case of the rod 1b that possesses a flexible binding site, both cis and trans isomers can form the corresponding pseudorotaxanes with association constants of (2.0 +/- 0.3) x 10(2) M(-1) for 2a and trans-1b and of (7.4 +/- 0.5) x 10(2) M(-1) for 2a and cis-1b in CDCl3 at 24 +/- 1 degrees C. In this system, therefore, external stimuli can modulate the relative distribution of the pseudorotaxane and its components. Finally, the work was extended to the construction of a kinetically more stable molecular machine based on a rotaxane-like complex 10.11 between a metallocycle 11 and a dumbbell 10. In this system, the complex and its components showed separate sets of the signals, not the averaged, in 1H NMR spectroscopy as expected by the increased kinetic stability.

A pseudorotaxane-based molecular machine controlled by light and thermal stimuli.

A new pseudorotaxane-based molecular machine exhibits extremely efficient switching between assembly and disassembly mode, controlled by the combination of light and thermal stimuli.