Response Characteristics of Pressure-Sensitive Conductive Elastomer Sensors Using OFC Electrode with Triangular Wave Concavo-Convex Surfaces.

The sensor response of pressure-sensitive conductive elastomers using polymeric materials can be adjusted by altering the type and quantity of fillers used during manufacturing. Another method involves modifying the surface shape of the elastomer. This study investigates the sensor response by altering the surface shape of an electrode using a readily available pressure-sensitive conductive elastomer. By employing an oxygen-free copper electrode with a flat surface (with surface roughness parameters Ra = 0.064 µm and Rz = 0.564 µm) as a baseline, we examined the sensor system's characteristics. Electrodes were fabricated with triangular wave concavo-convex surfaces, featuring tip angles of 60, 90, and 120°. Improved sensor responses were observed with electrodes having tip angles of 60 and 90°. Additionally, even with varying conductive properties of elastomers, the conductance of the elastomer sensor increased similarly when using an electrode with a 90° tip angle. This study demonstrates the potential for expanding the applications of conductive elastomer sensors, highlighting the noteworthy improvement in sensor response and performance achieved by altering the surface shape of electrodes used with commercially available conductive elastomers.

Evaluation of rooting characteristics of Ephedra cuttings by anatomy and promising strain selection based on rooting characteristics and alkaloid content.

The differences in rooting characteristics of cuttings prepared from E. sinica strains were investigated and found that cuttings prepared from strains with high rooting characteristics showed approximately 90% of the cuttings were rooted, whereas cuttings prepared from low rooting characteristics did not root. To understand the reason for this substantial difference, the anatomy of nodes was examined and found that adventitious roots were generated from the cortex and parenchyma in pith. Calculations of the correlation coefficients between the rooting rate and the value of anatomy indicated that the rooting rate was positively correlated with the parenchyma in pith in the node. On the basis of the positive correlation, it is possible to estimate the rooting characteristics of new strains without having to prepare cuttings. Next, we conducted a screening for E. sinica strains on the basis of total alkaloids content [ephedrine (E) + pseudoephedrine (PE)] and selected strains having no less than 0.7% total alkaloids content as defined by the Japanese Pharmacopoeia 18th edition. Strains having characteristic E or PE content were uncovered: E-rich strains had 100% E content and PE-rich strains had 99% PE content. We were able to select E. sinica strains on the basis of two factors: high rooting rate of cuttings and high or characteristic alkaloid content. These strains are valuable for breeding.

Seasonal variation of alkaloids and polyphenol in Ephedra sinica cultivated in Japan and controlling factors.

We investigated the seasonal variation of alkaloids (ephedrine and pseudoephedrine), total polyphenol, and sugar contents in Ephedra sinica cultivated in Japan and elucidated the controlling factors for the variation. In 2018, alkaloids and polyphenol contents increased dramatically from May to July, decreased to their lowest in October, and slightly increased again in November. The reduction of alkaloids and polyphenol contents in the autumn may be affected by precipitation in summer. In 2020, alkaloids and polyphenol contents started to decrease in late July when rainfall was abundant from July to August. In contrast, sucrose and starch contents continued to increase until September and remained high until October. Vascular bundles and fiber developed, and herbal stem weight increased from August to October. Alkaloids and total polyphenol contents tended to increase in November. At the same time, starch and sucrose contents decreased dramatically, whereas glucose and fructose contents increased. Sugar content decreased from October and was lowest in November. The seasonal variation of alkaloids and total polyphenol contents exhibited a contrasting tendency to the seasonal variation of sugar content and tissue development. The seasonal variation of alkaloids and total polyphenol contents was caused by the seasonal variation of sugar content and tissue development. In addition, it is suggested that anatomy may be used for alkaloids content estimation in Ephedra plants.

Highly luminescent MAPbI3 perovskite quantum dots with a simple purification process via ultrasound-assisted bead milling.

Organic-inorganic hybrid lead halide perovskite quantum dots (QDs) have various excellent optical properties, and they have drastically enhanced the field of light-emitting diode (LED) research. However, red-emissive CH3NH3 (MA) PbI3 QDs have worse optical properties compared with those of green-emissive MAPbBr3 QDs due to their instability under high-moisture and high-temperature conditions. Therefore, it is quite difficult to prepare MAPbI3 QDs with good optical properties via bottom-up methods using conditions involving high temperature and high-solubility solvents. On the other hand, top-down methods for preparing MAPbI3 QDs under an air atmosphere have attracted attention; however, there are issues, such as PL emission with a wide FWHM being obtained due to the wide particle-size distribution. In this research, red-emissive MAPbI3 QDs were prepared via an ultrasound-assisted bead milling (UBM) method, and the MAPbI3 QDs were purified using various carboxylate esters. As a result, we solved the issue of the wide particle-size distribution unique to top-down methods via purifying the MAPbI3 QDs, and they achieved the following excellent optical properties: a FWHM of 44 to 48 nm and a PLQY of over 60%. Notably, a fabricated LED device with MAPbI3 QDs purified using methyl acetate showed a PL peak at 738 nm and a FWHM of 49 nm, resulting in an excellent EQE value of 3.2%.

Li@C60 thin films: characterization and nonlinear optical properties.

Organic materials have attracted considerable attention in nonlinear optical (NLO) applications as they have several advantages over inorganic materials, including high NLO response, and fast response time as well as low-cost and easy fabrication. Lithium-containing C60 (Li@C60) is promising for NLO over other organic materials because of its strong NLO response proven by theoretical and experimental studies. However, the low purity of Li@C60 has been a bottleneck for applications in the fields of solar cells, electronics and optics. In 2010, highly purified Li@C60 was finally obtained, encouraging further studies. In this study, we demonstrate a facile method to fabricate thin films of Li@C60 and their strong NLO potential for high harmonic generation by showing its comparatively strong emission of degenerate-six-wave mixing, a fifth-order NLO effect.

Water-mediated polyol synthesis of pencil-like sharp silver nanowires suitable for nonlinear plasmonics.

We report a simple method to control the end shape of silver nanowires by adding pure water in the conventional polyol synthesis. The use of 0.2-0.4% (v/v) water in ethylene glycol as a solvent provides pencil-like silver nanowires with sharp ends in a high yield. We have demonstrated remote excitation of SHG on the sharp nanowires, promising a point light source for super resolution microscopy.

Photoconductive Properties of Dibenzotetrathiafulvalene-Tetracyanoquinodimethane (DBTTF-TCNQ) Nanorods Prepared by the Reprecipitation Method.

Charge-transfer complex crystals have been extensively studied because of their metallic conductivity, photoconductivity, ambipolar charge transport, and high career mobility. Numerous studies of their applications for organic electric devices such as organic field effect transistors and solar cells have reported. However, bulky single crystals of charge-transfer complexes are difficult to handle, specifically to be made into a form of a thin film. Recently, nano/micro crystallization of charge-transfer crystal is attracted to realize thin film applications. In this paper, charge transfer complex nanorods composed of dibenzotetrathiafulvalene-tetracyanoquinodimethane (DBTTF-TCNQ) were prepared by the reprecipitation method. The as-formed nanorods possess a kinetically metastable crystal structure different from the thermodynamically stable bulk crystal prepared by slow evaporation of the solvent. From photoconductive measurement, nanorod stacks show a significant photosensitivity (354.57 µA/W) on par with bulk crystal (417.14 µA/W). These results suggest dibenzotetrathiafulvalene-tetracyanoquinodimethane (DBTTF-TCNQ) nanorods have a favorable crystal structure for carrier transport due to the difference of molecular stacking assembly.