The effect of thiophene sequence separation on air-stable organic thin-film transistor materials

The relationship between thiophene sequences and organic thin-film transistor (OTFT) characteristics was studied to determine their effect on ionization potential, molecular orientation, and air stability. Two types of molecular structures were used: continuous sequence and divided sequence thiophenes. The length of thiophene sequence did not affect FET characteristics but did affect ionic potential and air stability. Furthermore, materials with divided thiophene sequences showed no change in OTFT characteristics when exposed to air. These results suggest that separation of thiophene sequences can improve air stability, which is a problem of thiophene-based materials.     

Modeling and identification of an electrostatic motor

The present study describes modeling and parameter identification for a high-power electrostatic motor. The motor is a synchronous motor with six phases that is modeled by a six-terminal capacitance network. A method to measure the capacitance coefficient matrix of a network using an LCR tester is proposed and demonstrated. The thrust force of the motor is shown analytically using the proposed model, which shows good agreement with empirical measurements of the motor behavior. Based on the proposed model, the effect of electrode skew is analyzed for force ripple reduction. Using the analysis, a skew motor is fabricated and tested, with the results demonstrating that a skewing electrode with a skew factor π can considerably reduce thrust force ripple.     

Liquid Quinones for Solvent‐Free Redox Flow Batteries

Liquid benzoquinone and naphthoquinone having diethylene glycol monomethyl ether groups are designed and synthesized as redox active materials that dissolve supporting electrolytes. The Li‐ion batteries based on the liquid quinones using LiBF₄/PC show good performance in terms of voltage, capacity, energy efficiency, and cyclability in both static and flow modes. A battery is constructed without using intentionally added organic solvent, and its high energy density (264 W h L^?1) demonstrates the potential of solvent‐free organic redox flow batteries using liquid active materials.     

Synthesis of soluble oligsiloxane-end-capped hyperbranched polyazomethine and their application to CO2/N2 separation membranes

Three soluble hyperbranched polyazomethines containing oligosiloxane end group HBP-PAZ-SiO_n were successfully synthesized. HBP-PAZ-SiO_ns were used as modifiers of ethyl cellulose (EC) and polysulfone (PS) membranes. Blend membranes, HBP-PAZ-SiO_n/EC and HBP-PAZ-SiO_n/PS were prepared by blending the THF solution of HBP-PAZ-SiO_n with ethanol solution of EC and dichloromethane solution of PS, respectively. Surprisingly, the permeabilities for CO₂ of the blend membranes were more than 15–16 times higher than those of pure EC and PS membranes without any drop of pemselectivity to N₂. This unusual improvement has been achieved by both enhancement of diffusivity for carbon dioxide and nitrogen by the oligosiloxane groups and enhancement of affinity of the amino groups with carbon dioxide at the end groups of HBP-PAZ-SiO_n.     

Measurement of carbon sputtering yield by N ion beam and lifetime dependence of resulting foils on thickness

Carbon stripper foils with a higher nitrogen content were made by ion beam sputtering with reactive nitrogen gas. Such foils seem to be very useful as strippers for high-intensity heavy ion accelerators. To know further characteristics of the lifetime of such carbon foils, we have measured the sputtering yield of the carbon source material at a sputtering voltage of 4–15 kV and the lifetime dependence of such foils on thickness. Lifetime measurement was performed with a 3.2 MeV Ne⁺ ion beam. The sputtering yield on average showed 0.75 atoms/ion at over 9 kV sputtering voltage. The lifetime of the foils noticeably depends on the foil thickness, and the thickness range as practical stripper foil is to be around 15 to 33 μg/cm². Two foils made at 13 kV showed extremely long lifetimes of 6800 and 6000 mC/cm² at maximum and the foils made above 10 kV lived longer than about 900 mC/cm², which correspond to about 270 and 40 times longer than commercially available best foils. We measured the thickness ratio of nitrogen to carbon in each foil made at the different sputtering voltages and at the different irradiation stages (mC/cm²) by RBS method. We also inspected the structure of a nitrided carbon foil by transmission electron microscopy.     

Lifetime improvement of slackened thin cluster carbon stripper foils by suppression of carbon buildup

We control the amount of carbon buildup on slackened thin cluster carbon stripper foils (less than 3.5 μg/cm²) by heating with a high-power infrared lamp during beam bombardment. Foil lifetime measurements were performed using 2.0±0.5 μA beams of 3.2 MeV Ne⁺ ions and quantified as the total charge/area before breakage. Lifetimes were obtained up to 1286 mC/cm² at maximum and 1139 mC/cm² on the average; these values are, respectively, approximately 51 times at maximum and 46 times on average greater than the best commercially available foils, when used unheated and unslackened.     

Effect of cell structure on oil absorption of highly oil absorptive polyurethane foam for on-site use

This article reports the effect of cell structure on oil absorption of highly oil-absorptive polyurethane foam (ON-PUR), which is suitable for on-site foaming. We have developed ON-PUR as an oil absorbing polyurethane foam using a very reactive recipe. ON-PUR was synthesized by mixing polyol, water, additives, and polymeric diphenylmethane diisocyanate (P-MDI) using a high-pressure foaming machine. Density, airflow, oil absorption of this foam, and cell structure by microscopy were measured. From these results, it was found that the airflow of this foam increased by crushing, and the oil absorption of this foam increased sharply in a narrow airflow range (from 0.1 to 0.8 scfm). This increase is estimated to be due to the decrease of closed cell structures by crushing treatment. Furthermore, we constituted on-site foaming system in bench scale, which was expected to be applicable to on-site preparation of ON-PUR. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 179–186, 1997     

New type of pressurized cultivation method providing oxygen for piezotolerant yeast

For efficient oxygen supply to pressurized culture, we developed a method using a highly pressurized membrane reactor with an air-saturated medium circulation system. The new method increased the cell growth of aerobic yeast approximately 20 folds larger than that in the case of using a conventional method.     

Oxygen permeation properties and surface modification of acceptor-doped CeO2/MnFe2O4 composites

The preparation and oxygen permeation properties of the (Ce_0.8Pr_0.2)O_2−δ − x vol% MnFe₂O₄ composites, where x = 0 to 35, have been investigated. The samples were prepared by the Pechini method. In the case of Ce_0.8Pr_0.2O_2−δ, an oxygen flux density of 6 μmol⋅cm⁻²⋅s⁻¹ (L = 0.0247 cm) and the maximum methane conversion of 50% were attained at 1000^∘C. Unlike composites consisting of Gd-doped CeO₂ and MnFe₂O₄, the oxygen permeability of the (Ce_0.8Pr_0.2)O_2−δ – x vol% MnFe₂O₄ composites was almost constant regardless of the volume fraction of MnFe₂O₄; however, the optimum volume fraction of MnFe₂O₄ was determined to be 5 to 25 in the context of the chemical and mechanical stabilities under methane conversion atmosphere. In addition, the surface modification of the (Ce_0.8Gd_0.2)O_2−δ – 15 vol% MnFe₂O₄ composite was performed by using the FePt nanoparticles. The catalyst loading of 2.8 mg/cm² on the both side of the 0.3 mm-thick (Ce_0.8Gd_0.2)O_2−δ – 15vol% MnFe₂O₄ composite increased the oxygen flux density from 0.30 to 0.76 μmol⋅cm⁻²⋅s⁻¹ in the case of He/air gradients; however, the effect seems to be reduced in the case of high oxygen flux density caused by a large pO₂ gradient. Moreover, the Langmuir-Blodgett film of the FePt nanoparticles were successfully prepared on the tape-cast (Ce_0.8Gd_0.2)O_2−δ – 15vol% MnFe₂O₄ composite. Hydrophobic treatments for the surface of the composite were crucial to achieve high transfer ratio for the deposition of the LB film.