Effects of Diphenyl Dichalcogenides on the Radical Polymerization of Diethynyl Disulfide Derivative

Radical reaction of bis(4-prop-2-ynyloxyphenyl) disulfide (1) with 2,2′-azobis(isobutyronitrile) as an initiator provided a polymer with dithioalkene units (2). The ¹H and ¹³C NMR spectra of 2 showed that 2 had mainly E-form dithioalkene structure. The radical reactions of 1 and diphenyl diselenide (3) or diphenyl ditelluride (5) were also carried out. At higher temperature than 70 °C, polymers were obtained with less amount of AIBN than in the case of the homopolymerization of 1. Addition of 3 or 5 in the reaction mixture appeared to promote the radical reaction. Moreover, the obtained structure has high contents of thio-seleno alkene or thio-telluro alkene than expected, which is due to difference of the chalcogen radical reactivity and difference of capture ability of the dichalcogenide.

Negative photoinduced current and negative differential characteristics of new optoelectronic sensors with InAs/GaAs nanostructure for visual recognition

Negative photo-induced currents and negative differential characteristics of photoinduced current have been obtained successfully under weak photoexcitations at 300 K for a new optoelectronic sensor including a carrier-storage layer of InAs/GaAs short period superlattice. The phenomena are useful to imitate the selectivity functions in visual recognition, which is based on the difference-of-Gaussian functionlike distribution of light sensitivity in the receptive fields in visual cortex. The phenomena are strongly dependent on the material of the carrier-storage layer, where the photogenerated carriers are separated spatially due to the Schottky forward voltage. The carrier separation is more enhanced as the ratio of electron mobility to hole mobility becomes higher for the material of the carrier-storage layer. This means the In-rich InGaAs material is superior to the Ga-rich one. In addition, compared with In _x Ga_1-x As alloy, the improved surface morphology, the high electron mobility at room temperature and the narrow energy bandgap are observed in the case of InAs/GaAs short period superlattice. That is the InAs/GaAs short period superlattice is superior to In _x Ga_1-x As alloy as the material for the carrier-storage layer.     

Corporate productivity and the stages of ICT development

A number of studies have considered the impact of Information and Communication Technology (ICT) on corporate productivity, including the relationship of ICT to corporate structure and business processes. Comparatively less attention, however, has been directed toward the relationship between corporate productivity and the various stages of ICT application development; to date, the only work in this direction has been the proposal of some conceptual frameworks for the development stages of ICT, and no empirical studies have been conducted. In this paper, using individual data from the 2006 Information and Communication Technology Survey conducted by Japan’s Ministry of Economy, Trade and Industry, we use estimated production functions to quantify how productivity changes with the stages of ICT development. When we classify ICT applications into four stages of sophistication—nonperforming ICT assets, section-wide system applications, company-wide system applications, and inter-corporate system applications—we find that the impact of ICT on productivity increases with each successive stage of sophistication. For instance, when we use a production function that assesses the impact of the ICT development stage on Total Factor Productivity (TFP), we find that companies that have developed company-wide system applications exhibit added-value productivity some 1.07-fold higher than companies that have only progressed as far as the development of section-wide system applications. We also find that companies that have developed inter-corporate system applications exhibit added-value productivity some 1.11-fold higher than companies with only company-wide system applications.     

Thermoluminescence and induced absorption in X-ray-irradiated CdS-doped glasses

Thermoluminescence of X-ray-irradiated CdS-doped glasses has been measured, and relation between thermoluminescence and induced absorption in the X-ray-irradiated CdS-doped glasses has been investigated. The effect of thermal annealing and the X-ray energy dependence of thermoluminescence is different from that on the induced absorption. Therefore, defects, which are responsible for thermoluminescence, are considered to be different from those responsible for the induced absorption.     

Room temperature redox reaction by oxide ion migration at carbon/Gd-doped CeO2 heterointerface probed by an in situ hard x-ray photoemission and soft x-ray absorption spectroscopies

Abstract

In situ hard x-ray photoemission spectroscopy (HX-PES) and soft x-ray absorption spectroscopy (SX-XAS) have been employed to investigate a local redox reaction at the carbon/Gd-doped CeO₂ (GDC) thin film heterointerface under applied dc bias. In HX-PES, Ce3d and O1s core levels show a parallel chemical shift as large as 3.2 eV, corresponding to the redox window where ionic conductivity is predominant. The window width is equal to the energy gap between donor and acceptor levels of the GDC electrolyte. The Ce M-edge SX-XAS spectra also show a considerable increase of Ce³⁺ satellite peak intensity, corresponding to electrochemical reduction by oxide ion migration. In addition to the reversible redox reaction, two distinct phenomena by the electrochemical transport of oxide ions are observed as an irreversible reduction of the entire oxide film by O₂ evolution from the GDC film to the gas phase, as well as a vigorous precipitation of oxygen gas at the bottom electrode to lift off the GDC film. These in situ spectroscopic observations describe well the electrochemical polarization behavior of a metal/GDC/metal capacitor-like two-electrode cell at room temperature.     

Extracting mobile objects by sequential background detection on a video

This paper describes a technique for extracting moving objects from a video image sequence taken by a slowly moving camera as well as a fixed camera. The background subtraction method is effective for extracting moving objects from a video. But the latest background image should be employed for the subtraction in the mobile camera case and in order not to be influenced by the light intensity change. A temporal median technique is proposed in this paper which detects the background at every moment. The camera motion is estimated using a local correlation map and the temporal median filter is applied to the common image area among a set of successive image frames to extract the background. The technique was applied to the video images obtained at a junction from a hand-held camera and those taken at a pedestrians crossing by a camera fixed in a car and successfully detected pedestrians. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

A novel gossip-based sensing coverage algorithm for dense wireless sensor networks

Wireless sensor networks (WSNs) have been widely studied and usefully employed in many applications such as monitoring environments and embedded systems. WSNs consist of many nodes spread randomly over a wide area; therefore, the sensing regions of different nodes may overlap partially. This is called the “sensing coverage problem”. In this paper, we define a maximum sensing coverage region (MSCR) problem and present a novel gossip-based sensing-coverage-aware algorithm to solve the problem. In the algorithm, sensor nodes gossip with their neighbors about their sensing coverage region. In this way, nodes decide locally to forward packets (as an active node) or to disregard packets (as a sleeping or redundant node). Being sensing-coverage-aware, the redundant node can cut back on its activities whenever its sensing region is k-covered by enough neighbors. With the distributed and low-overhead traffic benefits of gossip, we spread energy consumption to different sensor nodes, achieve maximum sensing coverage with minimal energy consumption in each individual sensor node, and prolong the whole network lifetime. We apply our algorithm to improve LEACH, a clustering routing protocol for WSNs, and develop a simulation to evaluate the performance of the algorithm.