Co-existence of Bi with multiple valence states in zeolites - Controlling the optical properties by annealing atmosphere

We investigate the effect of annealing atmosphere on the optical properties of Bi doped zeolites by diffuse reflectance, steady state and time-resolved photoluminescence (PL), and PL excitation measurements. The results reveal that zeolites can be used as an excellent host material to stabilize multiple Bi centers (Bi³⁺, Bi²⁺, and Bi-related near-infrared (NIR) active centers) in the framework, which shows ultra-broadband emission from visible to NIR range. Annealing in N₂ leads to the partial conversion of Bi³⁺ ions into Bi²⁺ and Bi-related NIR active centers. Our results demonstrate that the broadband NIR emission may be attributed to the electronic transition of Bi low valence state, rather than a higher valence state.     

ITO thin-film transparent conductors: Microstructure and processing

Physical vapor deposition is used for the growth of thin-film indium-tin oxide (ITO) on suitable substrates. Indium-tin oxide is an essential component in many important technologies, including flat-panel display devices where ITO is used as an electrode since it is both transparent to visible light and has a relatively low electrical resistivity. In this review, scanning electron microscopy and transmission electron microscopy images are presented that illustrate the dependence of ITO microstructure on specific growth conditions. For example, it is shown that at a given substrate temperature, the impingement of energetic ions on the growth surface results in small (10–20 nm) subgrain regions within larger (200–600 nm in diameter) columnar grains. Observations of ITO deposited by sputter deposition, by high-density plasma enhanced evaporation, and by simple electron-beam evaporation are presented and discussed.     

Impacts of a heavy storm of rain upon dissolved and particulate organic C, N and P in the main river of a vegetation-rich basin area in Japan

The impacts of a heavy storm of rain upon the dissolved and particulate organic matter (OM), nitrogen (N) and phosphorus (P) in the main river of the vegetation-rich Nagara River basin were investigated using water samples collected along the river line during a critical typhoon-induced heavy rain storm event. Besides, based on a high performance size-exclusion chromatography (HPSEC) system, the variance of dissolved OM (DOM) in its molecular weight (MW) characteristics was also assessed. From the MW standpoint, DOM components merged into the river along the river line resembled those present in its headwater. The MW range changed only slightly from 1010 to 5900 at the upstream (US), to 1130-5900 and 1200-5900 Da at the midstream (MS) and downstream (DS), respectively, while the corresponding weight-averaged MW (M(w)) decreased from 3669 to 3330 and 2962 Da. The heavy storm of rain enhanced the content of DOM; however, apart from a small larger-MW fraction (about 5900-6800 Da), the newly emerged DOM constituents exhibited an MW range similar to those existed before the storm. Due also to the storm of rain, total P and N (TP and TN) changed markedly in the ranges of 6.6-11.9, 8.3-40.6 and 48.4-231.3 microg/l for TP, and 145.4-296.0, 502.2-1168.7 and 1342.7-1927.3 microg/l for TN at the US, MS and DS, respectively. The larger values of TP and TN generally appeared for samples at elevated river water levels. The enhanced presence of P was found largely attributed to its particulate form; while, for N, the contribution from its dissolved form was significant. The newly emerged suspended particles via the storm-water contained lower content of OM, N and P, and a general decreasing trend of the particulate OM, N and P along the river line was also confirmed. The C/N ratio in the dissolved form varied in 0.7-6.7 and decreased downstream, while, that in the particulate form 2.3-17.3. Suspended particles that emerged in the river water during the storm exhibited larger C/N values. N/P in both dissolved and particulate forms varied in the ranges of 2.2-17.1 and 12.9-444.9, respectively, and a general trend of either increasing or decreasing in relation to the storm of rain was not revealed.     

First-principles simulations of removal process in EEM (Elastic Emission Machining)

Interactions between ultra-fine powder [SiO₂] and work [Si (1 0 0) surface] in EEM (Elastic Emission Machining) has been investigated by employing first-principles molecular dynamics (MD) simulations. Calculated results show the possibilities of the atomic removal through the solid phase chemical interaction between surfaces of ultra-fine powders and works.     

Algorithms to Select IDDQ Measurement Vectors for Bridging Faults in Sequential Circuits

In order to reduce IDDQ testing time, it is important to reduce the number of IDDQ measurement vectors, because IDDQ measurement is a time-consuming process. For obtaining minimum number of IDDQ measurement vectors for sequential circuits, fault simulation needs to be performed without fault-dropping, thus requiring very high simulation time. In this paper we propose algorithms to select small number of IDDQ measurement vectors. The proposed algorithms can concurrently simulate multiple faults and use heuristics for selection of IDDQ measurement vectors to reduce simulation time. Experimental results are presented to demonstrate the effectiveness of the proposed method.     

Aqueous solution-based synthesis of rare earth-doped metal oxide thin films

Rare earth-doped TiO₂ thin films have been successfully formed on glass and Si wafer substrates from aqueous solution through equilibrium reaction between metal–fluoro complex and metal oxide, in which Ln³⁺–ethylenediaminetetraacetic acid (EDTA) complex (Ln: rare earth metal) was added into the reaction solution. Ln/Ti ratio and crystalline structure of the film could be controlled by varying the initial concentration of Ln³⁺–EDTA complex solution. The obtained Ln-doped films were densely-packed and had no cracks.     

Decoding of depth and motion in ambiguous binocular perception

We have shown previously that random dots with an interocular time delay (ITD), the time difference of the onset of dots between the two eyes, yield both apparent depth and motion, although depth and velocity are covariant and, thus, ITD is inherently ambiguous. The depth of random dots with ITD was proportional to ITD, suggesting that the visual system assumes a constant velocity of the dots and determines depth on the basis of this constant velocity. We performed psychophysical experiments to investigate whether subjects perceive a constant velocity with a variety of ITDs in random dots aligned along a single vertical line that ensures neither apparent motion nor accidental disparity between the dots. The results showed that subjects perceive a constant velocity for a variety of ITDs with simultaneous perception of depth in proportion to ITD, indicating the priority of depth over velocity in ambiguous binocular perception derived from ITD.     

Transmittance analysis of three-dimensional photonic crystals by the effective medium theory

A simple method for calculating the transmittance of three-dimensional photonic crystals is proposed. The crystals are divided into multilayer thin films, and each film is divided into rectangles with a minute width to calculate the effective permittivity of the film by the effective medium theory. Transmittance of the multilayer thin films is calculated with the matrix method. As the number of atomic layers increases, remarkable stop bands appear. When the refractive index of photonic atoms increases, the stop band shifts to a lower frequency, the band widens, and the number of bands increases. Polarization and incident angle dependences are also analyzed. The limit of application for this calculation method is also discussed.     

Ensemble Stimulation of Embryoid Bodies using Substrate-Embedded Electrodes

Precise control of differentiation processes of pluripotent stem cells is essential for regeneration medicine, and electrical stimulation is one of the promising techniques, particularly for the regulation of neuronal regeneration. In the present study, we developed substrates with embedded electrodes, which allowed ensemble electrical stimulation of embryoid bodies (EBs). Microcavity-array patterns were fabricated on substrates with embedded electrodes. Uniform-size EBs of P19 cells were prepared, inserted one by one in each microcavity, and electrical stimulation was applied through substrate electrodes. Stimulus-induced intracellular calcium transients were successfully monitored by fluorescence imaging. The results suggested that this method would be useful for applying precisely controlled electrical stimulation to a large number of EBs of stem cells. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.