Invited; Progress of p-channel oxide-TFT development and how we improve the performances

It is well known that n-channel oxide-TFTs, i.e. a-IGZO-TFT is a great success in TFT back-plane technology for the state-of-art AMFPDs because of their excellent device performances including high-mobility and low-off current characteristics and good mass-product liability compatible with large sized glass substrates. There are remaining issues such as the development of higher electron mobility and better stability channels and intense device and material developments still take place. Therefore, several high mobility n-channel oxide-TFT have been developed already. (Fig.1) On the other hand, the absence of practical device quality of p-type channel oxide-TFT still remains the largest issue in an oxide semiconductor and is recognized as the technological barrier that should be overcome for next-generation oxide device technology because many circuit applications such as CMOS require a counterpart of n-channel-TFTs. Please click Download on the upper right corner to see the full abstract

Analytical Formulas of Molecular Ion Abundances and N2H+ Ring in Protoplanetary Disks

We investigate the chemistry of ion molecules in protoplanetary disks, motivated by the detection of N$_2$H$^+$ ring around TW Hya. While the ring inner radius coincides with the CO snow line, it is not apparent why N$_2$H$^+$ is abundant outside the CO snow line in spite of the similar sublimation temperatures of CO and N$_2$. Using the full gas-grain network model, we reproduced the N$_2$H$^+$ ring in a disk model with millimeter grains. The chemical conversion of CO and N$_2$ to less volatile species (sink effect hereinafter) is found to affect the N$_2$H$^+$ distribution. Since the efficiency of the sink depends on various parameters such as activation barriers of grain surface reactions, which are not well constrained, we also constructed the no-sink model; the total (gas and ice) CO and N$_2$ abundances are set constant, and their gaseous abundances are given by the balance between adsorption and desorption. Abundances of molecular ions in the no-sink model are calculated by analytical formulas, which are derived by analyzing the full-network model. The N$_2$H$^+$ ring is reproduced by the no-sink model, as well. The 2D (R-Z) distribution of N$_2$H$^+$, however, is different among the full-network model and no-sink model. The column density of N$_2$H$^+$ in the no-sink model depends sensitively on the desorption rate of CO and N$_2$, and the flux of cosmic ray. We also found that N$_2$H$^+$ abundance can peak at the temperature slightly below the CO sublimation, even if the desorption energies of CO and N$_2$ are the same.Comment: accepted to Ap

Ambipolar oxide thin-film transistor-based artificial synapses

Many intelligent behaviors, such as learning and perception, are affected by external environmental stimuli in the human nervous system. Therefore, one of the significant challenges is to develop an artificial synapse device with reconfigurable excitatory and inhibitory responses for artificial intelligence systems with human-like perceptual capability. Please click Download on the upper right corner to see the full abstract

On-chip constructive cell-Network study (I): Contribution of cardiac fibroblasts to cardiomyocyte beating synchronization and community effect

<p>Abstract</p> <p>Backgrounds</p> <p>To clarify the role of cardiac fibroblasts in beating synchronization, we have made simple lined-up cardiomyocyte-fibroblast network model in an on-chip single-cell-based cultivation system.</p> <p>Results</p> <p>The synchronization phenomenon of two cardiomyocyte networks connected by fibroblasts showed (1) propagation velocity of electrophysiological signals decreased a magnitude depending on the increasing number of fibroblasts, not the lengths of fibroblasts; (2) fluctuation of interbeat intervals of the synchronized two cardiomyocyte network connected by fibroblasts did not always decreased, and was opposite from homogeneous cardiomyocyte networks; and (3) the synchronized cardiomyocytes connected by fibroblasts sometimes loses their synchronized condition and recovered to synchronized condition, in which the length of asynchronized period was shorter less than 30 beats and was independent to their cultivation time, whereas the length of synchronized period increased according to cultivation time.</p> <p>Conclusions</p> <p>The results indicated that fibroblasts can connect cardiomyocytes electrically but do not significantly enhance and contribute to beating interval stability and synchronization. This might also mean that an increase in the number of fibroblasts in heart tissue reduces the cardiomyocyte 'community effect', which enhances synchronization and stability of their beating rhythms.</p

On-chip constructive cell-network study (II): on-chip quasi-in vivo cardiac toxicity assay for ventricular tachycardia/fibrillation measurement using ring-shaped closed circuit microelectrode with lined-up cardiomyocyte cell network

<p>Abstract</p> <p>Backgrounds</p> <p>Conventional <it>in vitro </it>approach using human ether-a-go-go related gene (hERG) assay has been considered worldwide as the first screening assay for cardiac repolarization safety. However, it does not always oredict the potential QT prolongation risk or pro-arrhythmic risk correctly. For adaptable preclinical strategiesto evaluate global cardiac safety, an on-chip quasi-<it>in vivo </it>cardiac toxicity assay for lethal arrhythmia (ventricular tachyarrhythmia) measurement using ring-shaped closed circuit microelectrode chip has been developed.</p> <p>Results</p> <p>The ventricular electrocardiogram (ECG)-like field potential data, which includes both the repolarization and the conductance abnormality, was acquired from the self-convolutied extracellular field potentials (FPs) of a lined-up cardiomyocyte network on a circle-shaped microelectrode in an agarose microchamber. When Astemisol applied to the closed-loop cardiomyocyte network, self-convoluted FP profile of normal beating changed into an early afterdepolarization (EAD) like waveform, and then showed ventricular tachyarrhythmias and ventricular fibrilations (VT/Vf). QT-prolongation-like self-convoluted FP duration prolongation and its fluctuation increase was also observed according to the increase of Astemizole concentration.</p> <p>Conclusions</p> <p>The results indicate that the convoluted FPs of the quasi<it>-in vivo </it>cell network assay includes both of the repolarization data and the conductance abnormality of cardiomyocyte networks has the strong potential to prediction lethal arrhythmia.</p

Fluorescent Gelators for Detection of Explosives

Carbazole-, quinoline-, benzothiazole-, and stilbene-containing fluorescent gelators are synthesized by connecting gelation-driving segments, and their gelation abilities are studied with 13 solvents. Fibrous thin-layer films are prepared on quartz plates from the solutions or gels, and they are studied as chemosensors for explosives. Fluorescence quenching of the films upon exposure to saturated TNT or RDX vapor is used to evaluate the abilities of the films to detect explosives. The relationship between the thickness of the thin-layer film and the quenching efficiency upon exposure to TNT is studied. The morphologies of the thin-layer films are observed by dynamic force mode scanning probe microscopy and discussed with regard to their fluorescence quenching. The interactions among chromophores in the gels, thin-layer films, and solutions are studied by variable-temperature spectroscopy. The mechanism of TNT detection is discussed from the viewpoint of the HOMO and LUMO energy levels.ArticleBULLETIN OF THE CHEMICAL SOCIETY OF JAPAN.89(11):1391-1401(2016)journal articl

Tracking sectoral allocation of official development assistance: a comparative study of the 29 Development Assistance Committee countries, 2011–2018

Background: Official development assistance (ODA) is one of the most important means for donor countries to foster diplomatic relations with low- and middle-income countries and contribute to the welfare of the international community. Objective: This study estimated the sectoral allocation of gross disbursements of ODA of the 29 Development Assistance Committee (DAC) member countries of the Organisation for Economic Co-operation and Development (OECD) for the duration of 2011 to 2018, by aid type (bilateral, multilateral, and both aids). Methods: Data from the OECD iLibrary were used. The sector definition was based on the OECD sector classification. For core funding to multilateral agencies that do not specialize in each aid sector, we estimated ODA and its flows based on the OECD methodology for calculating imputed multilateral ODA. Results: For all 29 countries, during the period of 2014–2018 where data were available for all the countries, the sector with the highest average annual ODA contribution was health at 20.34 billion USD (13.21%), followed by humanitarian aid at 18.04 billion (11.72%). Humanitarian aid has increased in the sectoral share rankings in both bilateral and multilateral aid, and the sectoral share for refugees in donor countries has increased in bilateral aid. While the 29 countries show relatively similar trends for sectoral shares, some countries and sectors display unique trends. For instance, infrastructure and energy sectors in bilateral aid of Japan are particularly high accounts for 48.48% of the total bilateral ODA of the country in 2018. Conclusions: This paper evaluated ODA trends by major donors of DAC countries in the pre-COVID-19 pandemic periods. We hope that our estimates will contribute to the review of the strategic decision-making and the effective implementation of future ODA policy discussions in the DAC countries while ensuring transparency