Memorial: The lost giant in Japan, Kyojiro Someya (1923-2000); Lost giant in Japan, Kyojiro Someya (1923-2000)

Kyojiro Someya, Professor emeritus of Waseda University, died suddenly before dawn on January 3, 2000, as he neared the age of 77. He had completed the correction of proofs of his last book, Accounting and Management of Cash Flow, on the day before, but to our regret could not write the preface. His academic achievements were his brilliant activities at home and abroad and his publication of over 90 books, including 24 coauthored, and more than 200 papers

Metal-fixed multiwalled carbon nanotube patterned emitters using photolithography and electrodeposition technique

We have demonstrated that patterned Cu-multiwalled carbon nanotube (MWCNT) composite emitters can be fabricated using a unique electrodeposition technique including a photolithography process. Well-regulated, patterned Cu-MWCNT composite emitters 50 mu m in diameter were formed on the conductive substrates. The MWCNTs were fixed on the patterned composite emitters. The field emission properties were studied by a diode-type measurement system. The field emission electric field was relatively low (1.5 V mu m(-1) for 1x10(-5) mu A cm(-2), 2.5 V mu m(-1) for 10 mu A cm(-2)). These composite emitters can be expected to be applied in field emission displays and other field emission devices. (C) 2008 The Electrochemical Society.ArticleELECTROCHEMICAL AND SOLID STATE LETTERS. 11(9):D72-D74 (2008)journal articl

Effects of Additives on Cu-MWCNT Composite Plating Films

The effects of plating bath additives on copper-multiwalled carbon nanotube (MWCNT) composite platings were studied. An acidified cupric sulfate electrolyte containing MWCNTs and polyacrylic acid as a dispersing agent was used as the base plating bath. Chloride ions (Cl⁻), poly(ethylene glycol), bis(3-sulfopropyl)disulfide (SPS), and Janus green B (JGB) were examined as additives. The surface morphologies and cross-sectional microstructures of the electrodeposited films were investigated, and the MWCNT content of the films was determined. Furthermore, the electrical resistivity and field emission properties of the films were evaluated. The simultaneous addition of Cl⁻, SPS, and JGB to the base plating bath was effective for forming smooth Cu-MWCNT composite films with a high MWCNT content over a wider range of current densities. The optimal bath composition was 0.85 mol dm⁻³　CuSO₄・5H₂O+0.55 mol dm⁻³ H₂SO₄+100 ppm PA5000+2 g dm⁻³ MWCNTs+2 ppm SPS + 2 ppm JGB +50 ppm Cl⁻. Cu-MWCNT composite films containing 0.15–0.33 mass % MWCNTs with smooth surface morphologies were formed in the current density range of 0.5–5 A dm⁻². The electrical resistivity of the films was around 2 μΩ cm, and they showed obvious field emission properties.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETYjournal articl

Field emission properties of Cu/multiwalled carbon nanotube composite films fabricated by an electrodeposition technique

Composite films of Cu and multiwalled carbon nanotubes (MWCNTs) were fabricated by an electrodeposition technique, and their field emission properties were examined. Commercially available MWCNTs with various diameters (60-150 nm) were used. The microstructure of the composite films was analyzed by scanning electron microscopy and the field emission properties were measured using a diode-type system. Cu/MWCNT composite films with homogeneous dispersion of MWCNTs were fabricated using each type of MWCNT. Bare MWCNTs were present on the surface of the composite films and the ends of the protruding tips were fixed by the deposited copper matrix. The composite films produced clear emission currents and the corresponding Fowler-Nordheim (F-N) plots showed that these were field emission currents. The turn-on electric field tended to decrease with decreasing MWCNT diameter. A light-emitting device incorporating the Cu/MWCNT composite film as a field emitter was fabricated, and its light-emitting properties were investigated. Light emission with a brightness of around 100 cd m(-2) was observed for approximately 100 h.ArticleJOURNAL OF APPLIED ELECTROCHEMISTRY. 43(4):399-405 (2013)journal articl

Cu-MWCNT Composite Films Fabricated by Electrodeposition

Copper–multiwalled carbon nanotube (MWCNT) composite plating using a sulfuric base bath was studied. A dispersing agent was used to disperse the MWCNTs into the plating bath. The effects of electrodeposition conditions on the surface morphology, microstructure, and MWCNT content in the composite films were examined. The internal stress, hardness, electrical conductivity, and thermal conductivity of the composite films were also investigated. The current density remarkably affected the surface morphologies of the films, and a relatively smooth surface was obtained at lower current densities. The bath temperature affected the microstructure of the composite films; a compact microstructure was formed at a lower temperature. The MWCNT content in the composite film increased with increasing MWCNT concentration in the plating bath, reaching a maximum value of 0.55 mass %. However, MWCNTs in the composite films tended to agglomerate for high MWCNT concentrations in the plating bath. An internal tensile stress was induced in the films. The hardness of the films was around 150 HV, and the electrical resistivity was approximately 2–2.5μΩ cm. The thermal conductivity of the Cu–0.42 mass % MWCNT composite film was 355 W m⁻¹ K⁻¹.ArticleJOURNAL OF THE ELECTROCHEMICAL SOCIETYjournal articl

Complementing regional ground GNSS-STEC computerized ionospheric tomography (CIT) with ionosonde data assimilation

A near-real-time computerized ionospheric tomography (CIT) technique was developed over the East Asian sector to specify the 3-D electron density field. The technique is based on a plethora of Global Navigation Satellite System observables within the region of interest which is bounded horizontally 110°–160°E and 10°–60°N and extending from 80 to 25, 000 km in altitude. Prior to deployment, studies validated the CIT results using ionosonde, middle-upper atmosphere radar and occultation data and found the technique to adequately reconstruct the regional ionosphere vertical structure. However, with room for improvement in estimating the peak height and avoiding physically unrealistic negative densities in the final solution, we present preliminary results from a technique that addresses these issues by incorporating CIT results into a data assimilation (DA) technique. The DA technique adds ionosonde bottomside measurements into CIT results, thereby improving the accuracy of the reconstructed bottomside 3-D structure. More specifically, on average CIT NmF2 and hmF2 improve by more than 60%. Further, during analysis, ionospheric electron densities are assumed to be better described by probability log-normal distribution, which introduces the positivity constraint that is mandatory in ionospheric imaging

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早大学位記番号:新8426早稲田大