Long‐Lived Flexible Displays Employing Efficient and Stable Inverted Organic Light‐Emitting Diodes

Although organic light‐emitting diodes (OLEDs) are promising for use in applications such as in flexible displays, reports of long‐lived flexible OLED‐based devices are limited due to the poor environmental stability of OLEDs. Flexible substrates such as plastic allow ambient oxygen and moisture to permeate into devices, which degrades the alkali metals used for the electron‐injection layer in conventional OLEDs (cOLEDs). Here, the fabrication of a long‐lived flexible display is reported using efficient and stable inverted OLEDs (iOLEDs), in which electrons can be effectively injected without the use of alkali metals. The flexible display employing iOLEDs can emit light for over 1 year with simplified encapsulation, whereas a flexible display employing cOLEDs exhibits almost no luminescence after only 21 d with the same encapsulation. These results demonstrate the great potential of iOLEDs to replace cOLEDs employing alkali metals for use in a wide variety of flexible organic optoelectronic devices.     

Characterization of mixing performance in a microreactor and its application to the synthesis of porous coordination polymer particles

Here we quantitatively evaluated the mixing performance of a tailor-made microreactor with central-collision type through the iodide/iodate chemical test reaction, and applied the microreactor to the synthesis of zeolitic imidazolate framework-8 (ZIF-8), which is a subclass of porous coordination polymers (PCPs) or metal organic frameworks (MOFs). The chemical test reaction demonstrated excellent mixing performance of the microreactor with a characteristic mixing time shorter than 1 ms, which is approximately 100 times faster than those of a batch reactor and a millimeter-sized Y-shaped mixer. Taking advantage of the rapid and uniform mixing, the microreactor successfully produced ZIF-8 particles with high reproducibility by simply mixing aqueous solutions of zinc nitrate and 2-methylimidazole. The synthesis at room temperature resulted in ZIF-8 particles with chamfered cube shape, while a lower temperature of 5 °C produced raspberry-type spherical particles. We confirmed that prepared ZIF-8 particles have BET surface area of ～1500 m²/g and exhibit the gate adsorption behavior caused by the structural transition of the ZIF-8 framework.     

Do people with social anxiety feel anxious about interacting with a robot?

AI & SOCIETY - To investigate whether people with social anxiety have less actual and “anticipatory” anxiety when interacting with a robot compared to interacting with a person, we...     

Effect of pH on microbial hydrogen fermentation

The influence of initial pH of the culture medium on hydrogen production was studied using sucrose solution and a mixed microbial flora from a soybean‐meal silo. Hydrogen production was not observed at pH values of 3.0, 11.0 and 12.0 but low production was observed at pH values 5.0 and 5.5. The pH of the experimental mixture decreased rapidly and produced hydrogen gas within 30 h. Methane was not detected at initial pH values between 6.0 and 10.0. The sucrose degradation efficiency increased as the initial pH value increased from 3.0 to 9.0. The maximum sucrose degradation efficiency of 95% was observed at pH 9.0. The maximum specific production yields of hydrogen, VFAs and alcohols were 126.9 cm³ g^?1 sucrose (pH of 9.0), 0.7 gCOD g^?1 sucrose (pH of 8.0) and 128.7 mgCOD g^?1 sucrose (pH of 9.0), respectively. The relationship between the hydrogen ion concentration and the specific hydrogen production rate has been mathematically described. The best kinetic parameters on the specific hydrogen production rate were K_OH = 1.0 × 10^?7 mol dm^?3 and K_H = 1.1 × 10^?4 mol dm^?3 (r² = 0.86). The maximum specific hydrogen production rate was 37.0 cm³ g^?1 VSS h^?1. © 2002 Society of Chemical Industry     

Formation energies and site preference of substitutional divalent cations in carbonated apatite

First-principles calculations were performed to examine defect formation energies and site preference of substitutional divalent cations M²⁺ (M = Mg, Cu, Zn, Cd, Sr, Pb, and Ba) in hydroxyapatite (HAp, Ca₁₀(PO₄)₆(OH)₂) and carbonated apatite (CAp). All inequivalent substitutional sites of and M²⁺ were investigated to determine their most preferential sites. For all M²⁺ studied, their defect formation energies for the most stable substitutional sites were lower in CAp than in hydroxyapatite (HAp), demonstrating that M²⁺ are preferentially substituted into CAp over HAp. For Ca sites in CAp, correlations between the defect formation energies and Ca-O bond lengths showed that bigger and smaller M²⁺ than Ca²⁺ are preferentially substituted for Ca sites with longer and shorter bond lengths than those in HAp, respectively. In addition, Ca sites with lower coordination numbers than 6 are preferentially substituted by Zn²⁺ and Cu²⁺ that originally tend to form 4- or 5-fold coordination in their phosphate crystals. substitution is therefore likely to effectively stabilize substitutional foreign ions by modifying bond lengths and coordination numbers of Ca sites from those in pure HAp. These effects may play an important role in enhancing the M²⁺ solubility into CAp.     

Methanogenic digestion using mixed substrate of acetic, propionic and butyric acids

Experiments on methanogenic digestion using high concentrations of mixed substrate were conducted. The major intermediate products of anaerobic digestion such as acetic, propionic and butyric acids were mixed in a ratio of 2:1:1 (COD basis), respectively, and used as a substrate for feeding into continuous-flow chemostat reactors maintained at 35°C. These reactors were operated stably at higher feed substrate concentrations and shorter hydraulic retention times (HRT) than those of using a single component of volatile fatty acids as a substrate. At an HRT of 4.43 days, the methanogenesis occurred normally up to a feed substrate concentration of 70,000 mg COD I⁻¹. At a feed substrate concentration of 20,000 mg COD I⁻¹, the methanogenesis occurred normally up to an HRT of 2.91 days and the minimum SRT for microbial populations was calculated to be 2.42 days. An increase in feed substrate concentration adversely affected the propionate degradation strikingly, while a decrease in HRT significantly adversely affected the acetate and propionate degradation. The methane production was 0.301 g⁻¹ COD utilized, and it was independent of the feed substrate concentration and HRT. Bacilli were predominant in all reactors, but sarcinae appeared in the reactors with high feed substrate concentrations and short HRTs. Phenomena in digester failure due to methanogen washout were also observed.     

Effect of nitrate on corrosion of austenitic stainless steel in boiling nitric acid solution containing chromium ions

The oxidation behavior of chromium and the corrosion behavior of austenitic stainless steel in boiling nitric acid solution containing highly concentrated nitrates were investigated using UV-visible spectroscopic measurements, Raman spectral measurements, immersion tests, and potentiodynamic polarization measurements. The oxidation rate measurement of chromium from Cr(III) to Cr(VI) was performed by 1 M boiling nitric acid solution containing each highly concentrated nitrates: Al(NO₃)₃, Nd(NO₃)₃, Ca(NO₃)₂, Mg(NO₃)₂, and NaNO₃ as a simulant of uranium nitrate in uranium concentrator in reprocessing plants. As a result, the rate of chromium oxidation was different depending on the added nitrates even at the same nitric acid concentration. In addition, the oxidation rate of chromium was increased with increasing the calculated partial pressure of nitric acid in consideration of the hydration of cation of nitrates. Furthermore, the corrosion rate of type 310 stainless steel was accelerated by the solution having a high chromium oxidation rate containing nitrates. These results indicated that the acceleration of the corrosion rate in the solutions depending on the oxidation rate of chromium, and the rate is affected by the salt-effect of nitrates.     

Segmented chirped grating for coarse wavelength division demultiplexing with multimode optical fibers

A chirped grating segmented into partitions each having a constant blaze angle to use in a demultiplexer for coarse wavelength division multiplexing with multimode optical fibers is developed. Its designed configuration utilizes a resonance region to achieve high diffraction efficiency and large dispersion. The width, blaze angle, and diffraction order of each partition were optimized by vector diffraction analysis. The diffraction loss of the manufactured grating was less than 1.5 dB, and polarization-dependent loss was less than 0.6 dB within a wavelength width of at least 70 nm. It is confirmed that a demultiplexer with the developed chirped grating had a wide passband and low cross talk.     

Noncompetitive detection of low molecular weight peptides by open sandwich immunoassay

Small peptides with less than 1000 in molecular weight are not considered amenable to sandwich immunoassays due to their difficulty of simultaneous recognition by two antibodies. As an alternative, we attempted noncompetitive detection of small peptides by open sandwich enzyme-linked immunosorbent assay (OS-ELISA) utilizing the antigen-induced enhancement of antibody VH/VL interaction. Taking fragments of human osteocalcin (BGP), a major non-collagen peptide produced in bone, as model peptides, OS immunoassay was performed using the cloned VH and VL cDNAs from two anti-BGP monoclonal antibodies either recognizing the N- or C-terminal fragment, respectively. When the clones were used for OS-ELISA with immobilized VL fragment and phage-displayed VH fragment, enhanced VH/VL interaction upon BGP addition was observed. Especially the clone for the C-terminal fragment showed a superior detection limit as well as a wider working range than those of competitive assay. The result was reproduced with purified VH-alkaline phosphatase and MBP-VL fusion proteins, where the latter was directly immobilized onto the microplate wells. The minimum detectable fragment was the hexamer including the C-terminus. This simple approach with a single monoclonal antibody with a short measurement time may prove a useful tool in immunodiagnostics as well as in proteomics research.     

Parameterization of aerosol and cirrus cloud effects on reflected sunlight spectra measured from space: application of the equivalence theorem

An original methodology to account for aerosol and cirrus cloud contributions to reflected sunlight is described. This method can be applied to the problem of retrieving greenhouse gases from satellite-observed data and is based on the equivalence theorem with further parameterization of the photon path-length probability density function (PPDF). Monte Carlo simulation was used to validate this parameterization for a vertically nonhomogeneous atmosphere including an aerosol layer and cirrus clouds. Initial approximation suggests that the PPDF depends on four parameters that can be interpreted as the effective cloud height, cloud relative reflectance, and two additional factors to account for photon path-length distribution under the cloud. We demonstrate that these parameters can be efficiently retrieved from the nadir radiance measured in the oxygen A-band and from the H(2)O-saturated area of the CO(2) 2.0 microm spectral band.