High‐resolution and high‐brightness full‐colour “Silicon Display” for augmented and mixed reality

High‐brightness micro‐LED display bonded onto silicon backplane has been successfully demonstrated. The 0.38‐inch full‐colour active matrix LED microdisplay system consists of 352 × 198 pixels. Each pixel is 24 μm square composed of red, green, and blue (RGB) subpixels corresponding to a pixel resolution of 1053 ppi. Quantum‐dot materials are formed on III‐nitride blue micro‐LED array to convert blue light into red and green for full‐colour operation. We have confirmed that this microdisplay, which we call “Silicon Display” has wide colour gamut exceeding 120% of sRGB. We describe the advantage of this colour‐converting approach for the full‐colour micro‐LEDs. Progress toward higher resolution is also described. Brightness of more than 30 000 cd/m² has been confirmed at a driving current density of 4 A/cm² for 3000 ppi blue monochrome micro‐LED prepared for full‐colour Silicon Display. We believe our “Silicon Display” is ideally suited for near‐to‐eye displays for augmented and mixed reality.     

Host emission from BaMgAl10O17 and SrMgAl10O17 phosphor: Effects of temperature and defect level

Abstract— Understanding the mechanism of blue‐light emission in Eu‐doped BAM phosphor as well as its sensitive degradation is required because this is a very important material in fluorescent lamps and plasma‐display panels. In this study, both theoretical and experimental investigations on the host emissions in BaMgAl¹⁰O¹⁷ and SrMgAl¹⁰O¹⁷ were performed. Host emissions from BaMgAl¹⁰O¹⁷ and SrMgAl¹⁰O¹⁷ by photoluminescence and thermoluminescence spectra were observed. Photoluminescence spectra suggested that the host emission from SrMgAl¹⁰O¹⁷ was easily quenched by thermal vibrations. The thermoluminescence spectra showed the existence of shallow and deep defect levels in BaMgAl¹⁰O¹⁷ and SrMgAl¹⁰O¹⁷ phosphors. It was shown that SrMgAl¹⁰O¹⁷ and its conduction plane could undergo degradation during irradiation of vacuum‐ultra‐violet (VUV) lights based on the calculated energy of formation of an oxygen vacancy. Moreover, the structural defects, such as oxygen vacancies, would cause localizing levels in the upper level in the valence band and in theconduction band. The results suggest the contribution of the host emission to the energy transfer to the Eu atoms would not be significant and the oxygen vacancies would act as the traps for excited carriers.     

Quantum chemistry and QSPR study on relationship between crystal structure and emission wavelength of Eu2+‐doped phosphors

Abstract— The relationship between crystal structures and emission properties has been computationally investigated for Eu²⁺‐doped phosphors. The electronic structure of the Eu²⁺‐doped BaMgAl¹⁰O¹⁷ phosphor was analyzed by using the quantum chemistry method. The different effects of O and Ba atoms on the Eu 5d states were determined. The presence of O and Ba atoms increases and decreases the energy level of the Eu 5d orbital by forming anti‐bonding and bonding interactions, respectively. According to the electronic‐structure analysis, the structure index that represents the local geometrical information of the Eu atom was defined. The relationship between the crystal structures and the emission wavelengths of the 1 6 Eu²⁺‐doped oxide phosphors were studied by using the quantitative structure‐property relationship (QSPR). The QSPR model suggested that the both O and alkaline‐earth atoms around the Eu atom are of importance in the determination of the emission wavelength. The interaction between the Eu and the nearest O atoms make the Eu²⁺ emission wavelength short. On the other hand, the interaction from the alkaline‐earth atoms around the Eu atom lengthens the Eu²⁺emission wavelength. This evaluation method is useful in selecting the host material that indicates a desirable emission wavelength of the Eu²⁺‐doped phosphors.     

Oxidation of HIPed TiC Ceramics in Dry O2, Wet O2, and H2O Atmospheres

Isothermal oxidation of dense TiC ceramics, fabricated by hot-isostatic pressing at 1630°C and 195 MPa, was performed in Ar/O₂ (dry oxidation), Ar/O₂/H₂O (wet oxidation), and Ar/H₂O (H₂O oxidation) at 900°–1200°C. The weight change measurements of the TiC specimen showed that the dry, wet, and H₂O oxidation at 850°–1000°C is represented by a one-dimensional parabolic rate equation, while the oxidation in the three atmospheres at 1100° and 1200°C proceeds linearly. Cross-sectional observation showed that the dry oxidation produces a lamellar TiO₂ scale consisting of many thin layers, about 5 μm thick, containing many pores and large cracks, while H₂O-containing oxidation decreases pores in number and diminishes cracks in scales. Gas evolution of CO₂ and H₂ with weight change measurement was simultaneously followed by heating the TiC to 1400°C in the three atmospheres. Cracking in the TiO₂ scale accompanied CO₂ evolution, and the H₂O-containing oxidation produced a small amount of H₂. A piece of single crystal TiC was oxidized in ¹⁶O₂/H₂¹⁸O to reveal the contribution of O from H₂O to the oxidation of TiC by secondary ion mass spectrometry.     

Pathogenesis of Babesia caballi infection in experimental horses

OBJECTIVE: The spread of nosocomial multiresistant microorganisms is affected by compliance with infection control measures and antibiotic use. We hypothesized that "colonization pressure" (ie, the proportion of other patients colonized) also is an important variable. We studied the effect of colonization pressure, compliance with infection control measures, antibiotic use, and other previously identified risk factors on acquisition of colonization with vancomycin-resistant enterococci (VRE). METHODS: Rectal colonization was studied daily for 19 weeks in 181 consecutive patients who were admitted to a single medical intensive care unit. A statistical model was created using a Cox proportional hazards regression model including length of stay in the medical intensive care unit until acquisition of VRE, colonization pressure, personnel compliance with infection control measures (hand washing and glove use), APACHE (Acute Physiology and Chronic Health Evaluation) 11 scores, and the proportion of days that a patient received vancomycin or third-generation cephalosporins, sucralfate, and enteral feeding. RESULTS: With survival until colonization with VRE as the end point, colonization pressure was the most important variable affecting acquisition of VRE (hazard ratio [HR], 1.032; 95% confidence interval [C1], 1.012-1.052; P=.002). In addition, enteral feeding was associated with acquisition of VRE (HR, 1.009; 95% CI, 1.000-1.017; P=.05), and there was a trend toward association of third-generation cephalosporin use with acquisition (HR, 1.007; 95% CI, 0.999-1.015; P=.11). The effects of enteral feeding and third-generation cephalosporin use were more important when colonization pressure was less than 50%. Once colonization pressure was 50% or higher, these other variables hardly affected acquisition of VRE. CONCLUSIONS: Acquisition of VRE was affected by colonization pressure, the use of antibiotics, and the use of enteral feeding. However, once colonization pressure was high, it became the major variable affecting acquisition of VRE.     

Flexible high‐resolution full‐color top‐emitting active‐matrix organic light‐emitting diode display

We developed a high‐performance 3.4‐in. flexible active‐matrix organic light‐emitting diode (AMOLED) display with remarkably high resolution using an oxide semiconductor in a backplane, by applying our transfer technology that utilizes metal separation layers. Using this panel, we also fabricated a prototype of a side‐roll display for mobile uses. In these AMOLED displays, a white OLED combined with a color filter was used in order to achieve remarkably high resolution. For the white OLED, a tandem structure in which a phosphorescent emission unit and a fluorescent emission unit are serially connected with an intermediate layer sandwiched between the emission units was employed. Furthermore, revolutionary technologies that enable a reduction in power consumption in both the phosphorescent and fluorescent emission units were introduced to the white tandem OLED.     

Influence of forecast accuracy of photovoltaic power output on capacity optimization of microgrid composition under 30‐minute power balancing control

A microgrid (MG) is one of the measures for enhancing the high penetration of renewable energy (RE)‐based distributed generators (DGs). If a number of MGs are controlled to maintain the predetermined electricity demand including RE‐based DGs as negative demand, they would contribute to supply–demand balancing of the whole electric power system. For constructing an MG economically, capacity optimization of controllable DGs against RE‐based DGs is essential. Using a numerical simulation model developed on the basis of a demonstrative study on an MG using PAFC and NaS battery as controllable DGs and photovoltaic power generation system (PVS) as an RE‐based DG, this study discusses the influence of the forecast accuracy of PVS output on capacity optimization. Three forecast cases with different accuracy are compared. The main results are as follows. Even with no forecast error during every 30‐minute period, the ideal forecast method, the required capacity of NaS batteries reaches about 40% of the PVS capacity for mitigating the instantaneous forecast error within 30 minutes. The required capacity to compensate for forecast error is doubled under the actual forecast method. The influence of forecast error can be reduced by adjusting the scheduled power output of controllable DGs according to weather forecasts. Besides, the required capacity can be reduced significantly if the error of balancing control in an MG is acceptable for a few percent of periods, because the total periods of large forecast error are not frequent. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(2): 20–29, 2013; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22328     

Chemiluminescence of indole and its derivatives induced by electrogenerated superoxide ion in acetonitrile solutions

Electrochemical behavior of the dioxygen (O₂)/superoxide ion (O₂ ⁻) redox couple in acetonitrile (AN) solutions containing indole compounds and no proton acceptor, and their chemiluminescence have been examined using spectroelectrochemical techniques. In AN solutions, in the presence of indole compounds having a substituent at the N-position (e.g. 1-methylindole and 1,2-dimethylindole), these indole compounds did not work as a proton donor to electrogenerated O₂ ⁻, and did not affect the redox reaction of the O₂/O₂ ⁻ couple. On the other hand, the indole compounds bearing a hydrogen at the N-position (e.g. indole, 3-methylindole (3-MI), tryptamine (TP), 3-indolemethanol and 3-indoleacetic acid) acted as a proton donor to O₂ ⁻. In addition, chemiluminescence was observed for some of the indole compounds having a hydrogen at the N-position and an electron-releasing group at the 3-position (i.e. TP, 2,3-dimethylindole, 2-(3-indole)-ethanol and 3-MI). The intensity of chemiluminescence of 3-MI was by far the strongest among those of the above four compounds. The chemiluminescent reaction of the indole compounds seemed to have close connection with electrogeneration of O₂ ⁻, which functioned as a proton acceptor to the indole compounds, and the chemical stability of a radical species (i.e. a one-electron oxidized form of conjugate base of indole compounds) due to the substituent which is present at the 3-position. The chemiluminescence was considered to occur via the formation of 1,2-dioxetane-like intermediates. The reaction mechanisms of chemiluminescence based on the electrogenerated O₂ ⁻ were briefly discussed.