Fabrication and Characterization of Colossal Electroresistance Chip Devices Composed of Polycrystalline Lanthanum-Doped Strontium Titanate and Palladium Electrodes

A colossal electroresistance (CER) multilayered chip device composed of polycrystalline 0.8-at% La-doped SrTiO₃ and Pd electrodes has been successfully fabricated. Polycrystalline SrTiO₃ devices exhibit large hysteresis in their current–voltage ( I – V ) characteristics after the forming process. Further, their resistance states can be switched by applying voltage pulses above ±50 V, and the resistance changes by approximately two orders of magnitude (from ∼600 Ω to ∼80 kΩ). These resistance-switching behaviors demonstrate that even ceramics can exhibit resistance changes as large as thin-film devices and provide the possibility of new switching devices with the memory effect composed of ceramics.     

Regeneration of initial activity of a pitch-based ACF for NO–NH3 reaction at ambient temperature

The reactivity of adsorbed NO (including NO₂) and NH₃ in the presence of 4.0% oxygen in He was examined over a pitch-based ACF calcined at 800°C. Regeneration at 30°C by 4% O₂ in He without NH₃ was found to be optimum for the recovery of the initial activity with complete removal of NO within 3 h, with minimum leaks of adsorbed NO and NH₃. A higher temperature of 40°C for regeneration increased the liberation of adsorbed NO, and NH₃ over ACF was rather slow at a lower temperature of 25°C, slow regeneration being achieved. Oxygen appears necessary to regenerate the ACF through enhancing the reaction of adsorbed NO and NH₃ for the initial activity, which was ascribed to the catalytic activity for NO–NH₃ and adsorption of both NO and NH₃. NH₃ in the gas phase appears to inhibit the regeneration reaction of adsorbed species, by using the leaking amount during the regeneration.     

In vivo EPR dosimetry to quantify exposures to clinically significant doses of ionising radiation

As a result of terrorism, accident or war, populations potentially can be exposed to doses of ionising radiation that could cause direct clinical effects within days or weeks. There is a critical need to determine the magnitude of the exposure to individuals so that those with significant risk can have appropriate procedures initiated immediately, while those without a significant probability of acute effects can be reassured and removed from the need for further consideration in the medical/emergency system. It is extremely unlikely that adequate dosemeters will be worn by the potential victims, and it also will be unlikely that prompt and accurate dose reconstruction at the level of individuals will be possible. Therefore, there is a critical need for a method to measure the dose from radiation-induced effects that occur within the individual. In vivo EPR measurements of radiation-induced changes in the enamel of teeth is a method, perhaps the only such method, which can differentiate among doses sufficiently to classify individuals into categories for treatment with sufficient accuracy to facilitate decisions on medical treatment. In its current state, the in vivo EPR dosemeter can provide estimates of absorbed dose of +/- 0.5 Gy in the range from 1 to >10 Gy. The lower limit and the precision are expected to improve, with improvements in the resonator and the algorithm for acquiring and calculating the dose. In its current state of development, the method is already sufficient for decision-making action for individuals with regard to acute effects from exposure to ionising radiation for most applications related to terrorism, accidents or nuclear warfare.     

Thermoresponsive Emission Switching via Lower Critical Solution Temperature Behavior of Organic–Inorganic Perovskite Nanoparticles

Lead halide perovskites have shown much promise for high‐performing solar cells due to their inherent electronic nature, and though the color of bright‐light emitters based on perovskite nanoparticles can be tuned by halide mixing and/or size control, dynamic switching using external stimuli remains a challenge. This article reports an unprecedented lower critical solution temperature (LCST) for toluene solutions containing methylammonium lead bromide (MAPbBr₃), oleic acid, alkylamines, and dimethylformamide. The delicate interplay of these molecules and ions allows for the reversible formation and decomposition of MAPbBr₃ nanoparticles upon heating and cooling, which is accompanied by green and blue photoemissions at each state. An intermediate 1D crystal with PbBr₂‐amine coordination is found to play pivotal role in this, and a mechanistic insight is provided based on a three‐state model. In addition to a high quantum yield (up to 85%), this system allows for control over the cloud point (30?80 °C) through compositional engineering and the luminescent color (blue to red) via halogen exchange, thus making it a versatile solution for developing functional molecular organic–inorganic LCST quantum dots.     

Effect of adding Pd nanoparticles to dimercaptan-polyaniline cathodes for lithium polymer battery

The electrochemical properties of 2,5-dimercapto-1,3,4-thiadiazole (DMcT)—polyaniline (PAn) composite films containing Pd nanoparticles (average diameter: 28 nm) were investigated. Compared to DMcT–PAn composite film, the DMcT–PAn composite film containing Pd nanoparticles showed enhanced redox current and discharge capacity. The enhanced activity is attributed to the nanosize dispersion of the Pd catalyst particles within the DMcT–PAn matrix. UV-Vis spectroscopy and X-ray photoelectron spectroscopy (XPS) results confirmed the interactions between DMcT and Pd nanoparticles. We have obtained the positive effect of Pd nanoparticles addition on the redox activity of the DMcT–PAn composite.     

New thermosetting resin from bisphenol A‐based benzoxazine and bisoxazoline

Bisphenol A‐based benzoxazine was prepared from bisphenol A, formaline, and aniline. Curing reaction of bisphenol A‐based benzoxazine with bisoxazoline and the properties of the cured resin were investigated. Consequently, using triphenylphosphite as a catalyst, for the first time the ring‐opening reaction of benzoxazine ring occurred at 170°C, and then the phenolic hydroxyl group generated by the ring‐opening reaction of the benzoxazine ring reacted with the oxazoline ring at 200°C. The melt viscosity of the molding compound was kept 0.1–1 Pa · s at 140°C even after 1.5 h, and increased rapidly at 180°C. It was realized that the molding compound showed good flowability below 140°C, curing reaction proceeded above 180°C rapidly. The cured resin from bisphenol A‐based benzoxazine and bisoxazoline showed good heat resistance, water resistance, electrical insulation, and mechanical properties, compared with the cured resin from bisphenol A‐type novolac and bisoxazoline. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1551–1558, 1999     

Effects of Frequency and Aeration Rate on Ultrasonic Oxidation of a Surfactant

The oxidation of surfactant (polyoxyethylene alkyl ether, C₁₄H₂₉O(CH₂CH₂)₇H, hereafter referred to as SS-70) induced by high power ultrasound is examined. The influences of aeration, bubble distribution, and frequency on the degradation rate are investigated. SS-70 is decomposed totally in a few hours. The optimum frequency for the degradation is observed. The decomposition rate of the surfactant is enhanced by the aeration and depends on the shape of the reactor. The optimum condition for the degradation process of ultrasonic oxidation is discussed.     

SO2 oxidation over the V2O5/TiO2 SCR catalyst

The effects of V₂O₅ loading of the V₂O₅/TiO₂ SCR catalyst on SO₂ oxidation activity were examined by infrared spectroscopy (DRIFT) and SO₂ oxidation measurement. Vanadium oxide added to the catalyst was found to be well dispersed over the TiO₂ carrier until covered with monolayer V₂O₅. The rate of SO₂ oxidation increased almost linearly with V₂O₅ loading below the monolayer capacity and attained saturation with further increase. The hydroxyl groups bonded to vanadium atoms, V–OH, might be altered by SO₂ oxidation. Both V=O and V–OH groups are likely involved in the adsorption and desorption of SO₂ and SO₃.