Mechanism for Local-Atomic Structure Changes in Chalcogenide-based Threshold-Switching Devices.

Threshold-switching devices based on amorphous chalcogenides are considered for use as selector devices in 3D crossbar memories. However, the fundamental understanding of amorphous chalcogenide is hindered owing to the complexity of the local structures and difficulties in the trap analysis of multinary compounds. Furthermore, after threshold switching, the local structures gradually evolve to more stable energy states owing to the unstable homopolar bonds. Herein, based on trap analysis, DFT simulations, and operando XPS analysis, it is determined that the threshold switching mechanism is deeply related to the charged state of Se-Se homopolar defects. A threshold switching device is demonstrated with an excellent performance through the modification of the local structure via the addition of alloying elements and investigating the time-dependent trap evolution. The results concerning the trap dynamics of local atomic structures in threshold switching phenomena may be used to improve the design of amorphous chalcogenides.

Effect of Marine-Derived Ice-Binding Proteins on the Cryopreservation of Marine Microalgae.

Ice-binding protein (IBPs) protect cells from cryo-injury during cryopreservation by inhibiting ice recrystallization (IR), which is a main cause of cell death. In the present study, we employed two IBPs, one, designated LeIBP from Arctic yeast, and the other, designated FfIBP from Antarctic sea ice bacterium, in the cryopreservation of three economically valuable marine microalgae, Isochrysis galbana, Pavlova viridis, and Chlamydomonas coccoides. Both of the IBPs showed IR inhibition in f/2 medium containing 10% DMSO, indicating that they retain their function in freezing media. Microalgal cells were frozen in 10% DMSO with or without IBP. Post-thaw viability exhibited that the supplementation of IBPs increased the viability of all cryopreserved cells. LeIBP was effective in P. viridis and C. coccoides, while FfIBP was in I. galbana. The cryopreservative effect was more drastic with P. viridis when 0.05 mg/mL LeIBP was used. These results clearly demonstrate that IBPs could improve the viability of cryopreserved microalgal cells.

Marine Antifreeze Proteins: Structure, Function, and Application to Cryopreservation as a Potential Cryoprotectant.

Antifreeze proteins (AFPs) are biological antifreezes with unique properties, including thermal hysteresis(TH),ice recrystallization inhibition(IRI),and interaction with membranes and/or membrane proteins. These properties have been utilized in the preservation of biological samples at low temperatures. Here, we review the structure and function of marine-derived AFPs, including moderately active fish AFPs and hyperactive polar AFPs. We also survey previous and current reports of cryopreservation using AFPs. Cryopreserved biological samples are relatively diverse ranging from diatoms and reproductive cells to embryos and organs. Cryopreserved biological samples mainly originate from mammals. Most cryopreservation trials using marine-derived AFPs have demonstrated that addition of AFPs can improve post-thaw viability regardless of freezing method (slow-freezing or vitrification), storage temperature, and types of biological sample type.

Dibenzothiopheno[6,5-b:6',5'-f]thieno[3,2-b]thiophene (DBTTT): high-performance small-molecule organic semiconductor for field-effect transistors.

We present the synthesis, characterization, and structural analysis of a thiophene-rich heteroacene, dibenzothiopheno[6,5-b:6',5'-f]thieno[3,2-b]thiophene (DBTTT) as well as its application in field-effect transistors. The design of DBTTT is based on the enhancement of intermolecular charge transfer through strong S-S interactions. Crystal structure analysis showed that the intermolecular π-π distance is shortened and that the packing density is higher than those of the electronically equivalent benzene analogue, dinaphtho-[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT). The highest hole mobility we obtained in polycrystalline DBTTT thin-film transistors was 19.3 cm(2)·V(-1)·s(-1), six times higher than that of DNTT-based transistors. The observed isotropic angular mobilities and thermal stabilities at temperatures up to 140 °C indicate the great potential of DBTTT for attaining device uniformity and processability.

Reliable and uniform thin-film transistor arrays based on inkjet-printed polymer semiconductors for full color reflective displays.

Stable uniform performance inkjet-printed polymer transistor arrays, which allow demonstration of flexible full-color displays, were achieved by new ambient processable conjugated copolymer semiconductor, and OTFT devices incorporating this material showed high mobility values>1.0 cm2 V(-1) s(-1). Bias-stress stability of the devices was improved with a channel-passivation layer, which suppresses the density of trap states at the channel interface.

A molecular design principle of lyotropic liquid-crystalline conjugated polymers with directed alignment capability for plastic electronics.

Conjugated polymers with a one-dimensional p-orbital overlap exhibit optoelectronic anisotropy. Their unique anisotropic properties can be fully realized in device applications only when the conjugated chains are aligned. Here, we report a molecular design principle of conjugated polymers to achieve concentration-regulated chain planarization, self-assembly, liquid-crystal-like good mobility and non-interdigitated side chains. As a consequence of these intra- and intermolecular attributes, chain alignment along an applied flow field occurs. This liquid-crystalline conjugated polymer was realized by incorporating intramolecular sulphur-fluorine interactions and bulky side chains linked to a tetrahedral carbon having a large form factor. By optimizing the polymer concentration and the flow field, we could achieve a high dichroic ratio of 16.67 in emission from conducting conjugated polymer films. Two-dimensional grazing-incidence X-ray diffraction was performed to analyse a well-defined conjugated polymer alignment. Thin-film transistors built on highly aligned conjugated polymer films showed more than three orders of magnitude faster carrier mobility along the conjugated polymer alignment direction than the perpendicular direction.