Coulomb blockade behaviors in individual Au nanoparticles as observed through noncontact atomic force spectroscopy at room temperature

Hattori, Shigeki,Kano, Shinya,Azuma, Yasuo,Tanaka, Daisuke,Sakamoto, Masanori,Teranishi, Toshiharu,Majima, Yutaka IOP Pub 2012 Nanotechnology Vol.23 No.18

<P>Coulomb blockade behaviors in individual Au nanoparticles of 2 nm core diameter in double-barrier structures have been studied by means of noncontact atomic force spectroscopy (NC-AFS) at room temperature. The Au nanoparticles with a 1-decanethiol ligand were chemisorbed by 1,10-decanedithiol molecules of a mixed 1-octanethiol/1,10-decanedithiol self-assembled monolayer coated on a Au(111) surface; these particles were observed through NC-AFS. NC-AFS measurements of the cantilever frequency shift–sample voltage (&Dgr;f–V<SUB>S</SUB>) curves were sequentially conducted on three Au nanoparticles under the same experimental conditions; the &Dgr;f–V<SUB>S</SUB> curves were found to deviate from the parabolic (&Dgr;f<SUB>N</SUB>) curve in the cases where no extra charge existed on the Au core. The experimental &Dgr;f<SUB>CB</SUB>(=&Dgr;f − &Dgr;f<SUB>N</SUB>) and &Dgr;f<SUB>CB</SUB>/V curves agree well with the theoretical curves obtained using a golden-rule calculation and the same parabolic parameters. All the results, through NC-AFS, suggest Coulomb blockade behaviors in the Au nanoparticles at room temperature.</P>

ADVANTAGES OF THE AKARI FIR ALL-SKY MAPS

YASUO DOI,SATOSHI TAKITA,TAKAFUMI OOTSUBO,KO ARIMATSU,MASAHIRO TANAKA,TAKAHIRO MORISHIMA,MITSUNOBU KAWADA,SHUJI MATSUURA,YOSHIMI KITAMURA,MAKOTO HATTORI,TAKAO NAKAGAWA,GLENN WHITE,NORIO IKEDA 한국천문학회 2017 天文學論叢 Vol.32 No.1

We present the {\it AKARI} far-infrared (FIR) all-sky maps and describe its characteristics, calibration accuracy and scientific capabilities. The {\it AKARI} FIR survey has covered 97\% of the whole sky in four photometric bands, which cover continuously 50--180 micron with band central wavelengths of 65, 90, 140, and 160 microns. The data have been publicly released in 2014 \citep{2015PASJ...67...50D} with improved data quality that have been achieved since the last internal data release \citep{2012PKAS...27..111D}. The accuracy of the absolute intensity is $\leq10$\% for the brighter regions. Quantitative analysis of the relative intensity accuracy and its dependence upon spatial scan numbers has been carried out. The data for the first time reveal the whole sky distribution ofinterstellar matter with arcminute-scale spatial resolutions at the peakof dust continuum emission, enabling us to investigate large-scaledistribution of interstellar medium in great detail. The filamentarystructure covering the whole sky is well traced by the all-sky maps. We describe advantages of the AKARI FIR all-sky maps for the study of interstellar matter comparing to other observational data.

AKARI FAR-INFRARED ALL-SKY SURVEY MAPS

Doi, Yasuo,Komugi, Shinya,Kawada, Mitsunobu,Takita, Satoshi,Arimatsu, Ko,Ikeda, Norio,Kato, Daisuke,Kitamura, Yoshimi,Nakagawa, Takao,Ootsubo, Takafumi,Morishima, Takahiro,Hattori, Makoto,Tanaka, Masa The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4

Far-infrared observations provide crucial data for the investigation and characterisation of the properties of dusty material in the Interstellar Medium (ISM), since most of its energy is emitted between ~ 100 and $200{\mu}m$. We present the first all-sky image from a sensitive all-sky survey using the Japanese AKARI satellite, in the wavelength range $50-180{\mu}m$. Covering > 99% of the sky in four photometric bands with four filters centred at $65{\mu}m$, $90{\mu}m$, $140{\mu}m$, and $160{\mu}m$ wavelengths, this achieved spatial resolutions from 1 to 2 arcmin and a detection limit of < 10 MJy $sr^{-1}$, with absolute and relative photometric accuracies of < 20%. All-sky images of the Galactic dust continuum emission enable astronomers to map the large-scale distribution of the diffuse ISM cirrus, to study its thermal dust temperature, emissivity and column density, and to measure the interaction of the Galactic radiation field and embedded objects with the surrounding ISM. In addition to the point source population of stars, protostars, star-forming regions, and galaxies, the high Galactic latitude sky is shown to be covered with a diffuse filamentary-web of dusty emission that traces the potential sites of high latitude star formation. We show that the temperature of dust particles in thermal equilibrium with the ambient interstellar radiation field can be estimated by using $90{\mu}m$, $140{\mu}m$, and $160{\mu}m$ data. The FIR AKARI full-sky maps provide a rich new data set within which astronomers can investigate the distribution of interstellar matter throughout our Galaxy, and beyond.

Effects of Strong Wind and Ozone on Localized Tree Decline in the Tanzawa Mountains of Japan

Suto, Hitoshi,Hattori, Yasuo,Tanaka, Nobukazu,Kohno, Yoshihisa Korean Society for Atmospheric Environment 2008 Asian Journal of Atmospheric Environment (AJAE) Vol.2 No.2

The numerical simulation of wind and ozone ($O_3$) transport in mountainous regions was performed with a computational fluid dynamics technique. A dry deposition model for $O_3$ was designed to estimate $O_3$ deposition in complex terrain, and the qualitative validity of the predicted $O_3$ concentration field was confirmed by comparison with observed data collected with passive samplers. The simulation revealed that wind velocity increases around ridge lines and peaks of mountains. The areas with strong wind corresponded well with the sites of tree decline at high altitudes, suggesting that it is an important factor in the localization of tree/forest decline. On the other hand, there is no direct relationship between forest decline and $O_3$ concentration. The $O_3$ concentration, however, tends to increase as wind velocity becomes higher, thus the $O_3$ concentration itself may be a potential secondary factor in the localized decline phenomena. While the diffusion flux of $O_3$ is not related to localized tree decline, the pattern of advection flux is related to those of high wind velocity and localized tree decline. These results suggest that strong wind with large advection flux of $O_3$ may play a key role in the promotion of tree/forest decline at high mountain ridges and peaks.

SMALL-SCALE STRUCTURE OF THE ZODIACAL DUST CLOUD OBSERVED IN FAR-INFRARED WITH AKARI

TAKAFUMI OOTSUBO,YASUO DOI,SATOSHI TAKITA,SHUJI MATSUURA,MITSUNOBU KAWADA,TAKAO NAKAGAWA,KO AROMATSU,MASAHIRO TANAKA,TORU KONDO,DAISUKE ISHIHARA,Fumihiko Usui,MAKOTO HATTORI 한국천문학회 2017 天文學論叢 Vol.32 No.1

The zodiacal light emission is the thermal emission from the interplanetary dust and the dominant diffuse radiation in the mid- to far-infrared wavelength region. Even in the far-infrared, the contribution of the zodiacal emission is not negligible at the region near the ecliptic plane. The AKARI far-infrared all-sky survey covered 97\% of the whole sky in four photometric bands with band central wavelengths of 65, 90, 140, and 160~$\mu$m. AKARI detected the small-scale structure of the zodiacal dust cloud, such as the asteroidal dust bands and the circumsolar ring, in far-infrared wavelength region. Although the most part of the zodiacal light structure in the AKARI far-infrared all-sky image can be well reproduced with the DIRBE zodiacal light model, there are discrepancies in the small-scale structures. In particular, the intensity and the ecliptic latitude of the peak position of the asteroidal dust bands cannot be reproduced precisely with the DIRBE models. The AKARI observational data during more than one year has advantages over the 10-month DIRBE data in modeling the full-sky zodiacal dust cloud. The resulting small-scale zodiacal light structure template has been used to subtract the zodiacal light from the AKARI all-sky maps.

THE FILAMENTARY WEB OF STAR FORMATION

White, Glenn J.,Doi, Yasuo,Komugi, Shinya,Kawada, Mitsunobu,Takita, Satoshi,Arimatsu, Ko,Ikeda, Norio,Kato, Daisuke,Kitamura, Yoshimi,Nakagawa, Takao,Ootsubo, Takafumi,Morishima, Takahiro,Hattori, Mak The Korean Astronomical Society 2012 天文學論叢 Vol.27 No.4

Following the first Public Release of the AKARI Point Source catalogues, we have worked on the production of a new far-infrared All-Sky Diffuse mapping product. In this paper we report first results from the All Sky diffuse maps that will shortly be released to the community, based on analysis of data from the Far Infrared Surveyor ($65{\mu}m-160{\mu}m$) instrument. These data are likely to have a strong impact on studies of extended structures, and the diffuse ISM.

Similarity of energy balance in mechanically ventilated compartment fires: An insight into the conditions for reduced-scale fire experiments

Suto Hitoshi,Matsuyama Ken,Hattori Yasuo 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.8

When evaluating energy balance and temperature in reduced-scale fire experiments, which are conducted as an alternative to full-scale fire experiments, it is important to consider the similarity in the scale among these experiments. In this paper, a method considering the similarity of energy balance is proposed for setting the conditions for reduced-scale experiments of mechanically ventilated compartment fires. A small-scale fire experiment consisting of various cases with different compartment geometries (aspect ratios between 0.2 and 4.7) and heights of vents and fire sources was conducted under mechanical ventilation, and the energy balance in the quasi-steady state was evaluated. The results indicate the following: (1) although the compartment geometry varies the energy balance in a mechanically ventilated compartment, the variation in the energy balance can be evaluated irrespective of the compartment size and geometry by considering scaling factor F (∝heffAwRT, where heff is the effective heat transfer coefficient, Aw is the total wall area, and RT is the ratio of the spatial mean gas temperature to the exhaust temperature); (2) the value of RT, which is a part of F, reflects the effects of the compartment geometry and corresponds to the distributions of the gas temperature and wall heat loss

Effects of aspect ratio on laboratory simulation of tornado-like vortices

Tang, Zhuo,Zuo, Delong,James, Darryl,Eguch, Yuzuru,Hattori, Yasuo Techno-Press 2018 Wind and Structures, An International Journal (WAS Vol.27 No.2

Experiments were conducted in a large-scale Ward-type tornado simulator to study tornado-like vortices. Both flow velocities and the pressures at the surface beneath the vortices were measured. An interpretation of these measurements enabled an assessment of the mean flow field as well as the mean and fluctuating characteristics of the surface pressure deficit, which is a manifestation of the flow fluctuation aloft. An emphasis was placed on the effect of the aspect ratio of the tornado simulator on the characteristics of the simulated flow and the corresponding surface pressure deficit, especially the evolution of these characteristics due to the transition of the flow from a single-celled vortex to a two-celled vortex with increasing swirl ratio.

An Evaluation Method for Tornado Missile Strike Probability with Stochastic Correlation

Yuzuru Eguchi,Takahiro Murakami,Hiromaru Hirakuchi,Soichiro Sugimoto,Yasuo Hattori 한국원자력학회 2017 Nuclear Engineering and Technology Vol.49 No.2

An efficient evaluation method for the probability of a tornado missile strike without usingthe Monte Carlo method is proposed in this paper. A major part of the proposed probabilityevaluation is based on numerical results computed using an in-house code, Tornado-bornemissile analysis code, which enables us to evaluate the liftoff and flight behaviors of unconstrainedobjects on the ground driven by a tornado. Using the Tornado-borne missileanalysis code, we can obtain a stochastic correlation between local wind speed and flightdistance of each object, and this stochastic correlation is used to evaluate the conditionalstrike probability, QV(r), of a missile located at position r, where the local wind speed is V. Incontrast, the annual exceedance probability of local wind speed, which can be computedusing a tornado hazard analysis code, is used to derive the probability density function,p(V). Then, we finally obtain the annual probability of tornado missile strike on a structurewith the convolutional integration of product of QV(r) and p(V) over V. The evaluationmethod is applied to a simple problem to qualitatively confirm the validity, and to quantitativelyverify the results for two extreme cases in which an object is located just in thevicinity of or far away from the structure.

Effects of aspect ratio on laboratory simulation of tornado-like vortices

Zhuo Tang,Delong Zuo,Darryl James,Yuzuru Eguchi,Yasuo Hattori 한국풍공학회 2018 Wind and Structures, An International Journal (WAS Vol.27 No.2

Experiments were conducted in a large-scale Ward-type tornado simulator to study tornado-like vortices. Both flow velocities and the pressures at the surface beneath the vortices were measured. An interpretation of these measurements enabled an assessment of the mean flow field as well as the mean and fluctuating characteristics of the surface pressure deficit, which is a manifestation of the flow fluctuation aloft. An emphasis was placed on the effect of the aspect ratio of the tornado simulator on the characteristics of the simulated flow and the corresponding surface pressure deficit, especially the evolution of these characteristics due to the transition of the flow from a single-celled vortex to a two-celled vortex with increasing swirl ratio.