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Journal Articles

NMR chemical shifts of $^{15}$ N-bearing graphene

Wang, X.*; Hou, Z.*; Ikeda, Takashi; Terakura, Kiyoyuki*

Journal of Physical Chemistry C, 118(25), p.13929 - 13935, 2014/06

Times Cited Count：10 Percentile：33.24(Chemistry, Physical)

The NMR chemical shifts of possible N-containing moieties at edges and defects of graphene are investigated by using the first-principles method. Our computations show that pyridine-like and graphite-like N are rather easily identifiable using $^{15}$ N NMR technique, in agreement with experiment. On the other hand, pyridinium-like N is hardly distinguished from pyrrole-like one because these $^{15}$ N nuclei give nearly overlapping signals. However, our simulations suggest that $^{1}$ H NMR is useful to discriminate between them; The NMR chemical shift of $^{1}$ H directly bonded with pyridinium-like and pyrrole-like N is estimated as 0.8 and 10.8 ppm, respectively. The $^{15}$ N NMR signals for various moieties at edges we considered are found to be similar to the corresponding ones at defects except for pyridine-like nitrogens. Conversely, the $^{15}$ N NMR chemical shifts are altered sensitively by the degree of aggregation of pyridine-like $^{15}$ N atoms both along armchair edges and at defect sites.

Journal Articles

Solutions of partial differential equations with the CIP-BS method

Utsumi, Takayuki*; Kimura, Hideo

JSME International Journal, Series B, 47(4), p.761 - 767, 2004/11

In this paper, we show that a new numerical method, the Constrained Interpolation Profile - Basis Set (CIP-BS) method, can solve partial differential equations (PDEs) with high accuracy and can be a universal solver by presenting examples for the solutions of typical parabolic, hyperbolic, and elliptic equations. Here, we present the numerical errors caused by this method, and illustrate that the solutions by the CIP-BS $^{2}$ method, in which fifth order polynomials are used to constrain the values and first and second order spatial derivatives, are highly refined compared to those by the CIP-BS $^{1}$ method, in which third order polynomials are used to constrain the values and first order spatial derivatives. The fact that this method can unambiguously solve PDEs with an one-to-one correspondence to analytical requirements is also shown for PDEs including singular functions like the Dirac delta function with Dirichet or Neumann boundary conditions. This method is straightforwardly applicable to PDEs describing complex physical and engineering problems.

Journal Articles

Solutions of hyperbolic equations with the CIP-BS method

Utsumi, Takayuki*; Yabe, Takashi*; Aoki, Takayuki*; Koga, J. K.; Yamagiwa, Mitsuru

JSME International Journal, Series B, 47(4), p.768 - 776, 2004/11

no abstracts in English

Journal Articles

A Note on the basis set approach in the constrained interpolation profile method

Utsumi, Takayuki*; Yabe, Takashi*; Koga, J. K.; Aoki, Takayuki*; Sekine, Masatoshi*; Ogata, Yoichi*; Matsunaga, Eiichi*

Journal of Computational Physics, 196(1), p.1 - 7, 2004/05

https://doi.org/10.1016/j.jcp.2003.10.019

Times Cited Count：3 Percentile：20.56(Computer Science, Interdisciplinary Applications)

no abstracts in English

Journal Articles

Quick sample preparation for analysis of dioxins in flue gas from municipal solid waste incinerator

Takigami, Machiko; Arai, Hidehiko*; Hirota, Koichi; Taguchi, Mitsumasa; Hakoda, Teruyuki; Kojima, Takuji

Kankyo Kagaku, 14(1), p.13 - 23, 2004/03

https://doi.org/10.5985/jec.14.13

The Japan Atomic Energy Research Institute undertook a pilot scale electron beam decompostion of dioxins in the flue gases from the municipal solid waste incinerator at the Takahama Clean Center. The conventional method, following the Japan Industrial Standards (JIS) method, takes 2 weeks at least to extract and purify dioxins from the flue gases for analysis by GC/MS. However, using a carbon adsorbent, the time required for the extraction of dioxins was shortened from 16 to 2.5 hours. Further improvements in the clean up process enabled the overall time to be reduced to less than a half of that rquired by the JIS method. Using this simplified method allows analysts, who are not practiced in the pretreatment of flue gases, to prepare samples for dioxin analysis by GC/MS. The sampling and pretreatment of the flue gases can, with this process, be completed within 4 days with accuracy comparable to JIS method.

Journal Articles