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91.
Yoshitaka Shimizu Yoko Ohte Xinnu Bao Satoko Otsuka Yuko Kitamaki Keiichiro Ishikawa Toshihide Ihara Kenji Kato 《Accreditation and quality assurance》2008,13(7):389-396
For accurate measurement of concentrations of substances by instrumental analysis, reliable calibration standards are needed.
In Japan, national reference materials are supplied under the national standards dissemination system named the Japan Calibration
Service System (JCSS). In JCSS, calibration standards for the analysis of environmental pollutants are supplied. For the traceability
to the SI of reference materials for calibration in JCSS, the National Metrology Institute of Japan (NMIJ) is developing high-purity
reference materials of volatile organic compounds (VOCs) as NMIJ CRMs. The freezing-point depression method, which has potential
as a primary method of measurement, is employed for the determination of property value. In this paper, a development scheme
of certified reference materials of high-purity VOCs is described.
Presented at BERM-11, October 2007, Tsukuba, Japan. 相似文献
92.
A long path atomic absorption cell has been modified to achieve high sensitvity in the determination of lead after MIBK extraction. This was achieved by using thermal insulation of the absorption cell and positioning the burner at an optimum angle. Insertion of rings inside the cell and oxygen supply line reduced the background noise to a low level while producing high sensitivities. This resulted in a marked improvement in detection limits for some metals in aqueous solution. 相似文献
93.
Ohara K Jacquinet JC Jouanneau D Helbert W Smietana M Vasseur JJ 《Journal of the American Society for Mass Spectrometry》2009,20(1):131-137
A better understanding of the biological roles of carbohydrates requires the use of tools able to provide efficient and rapid structural information. Unfortunately, highly acidic oligomers-such as polysulfated oligosaccharides-are very challenging to characterize because of their high polarity, structural diversity, and sulfate lability. These features pose special problems for matrix-assisted laser desorption/ionization mass spectrometric (MALDI-MS) analysis because polysulfated carbohydrates exhibit poor ionization efficiency and usually do not produce any signal. The present report demonstrates how MALDI-MS can be used to derive structural and compositional information from pure and mixed fractions of polysulfated oligosaccharides. Indeed, pyrenemethylguanidine (pmg, a derivatizing agent and ionization efficiency enhancer) was used for the analysis of di- to decasaccharides, carrying from two to nine sulfate groups. The method is applied to various highly sulfated chondroitin and carrageenan oligosaccharides as well as to the analysis of mixtures of compounds. In the mass spectra, the observation of a unique pmg-complexed ladder of peaks in both ionization modes allows an easy and rapid determination of both the number of sulfate groups carried by the analyte and its molecular weight. Moreover, we have developed a software tool for the rapid and automatic structural elucidation of carrageenans based on the mass spectra obtained. 相似文献
94.
Keitaro Kioka Tsuyoshi Honma Keiichiro Oh-ishi Sindy Reibstein Ning Da Lothar Wondraczek Takayuki Komatsu 《Journal of Non》2012,358(12-13):1523-1529
The crystallization behavior of 30Na2O–25Nb2O5–(45 ? x) SiO2–xAlO1.5 (x = 0, 2.5, and 5) (mol%) glasses was examined and the effect of Al2O3 addition on the formation of perovskite-type NaNbO3 crystals was clarified. It is found from X-ray diffraction analyses and transmission electron microscope observations that NaNbO3 nanocrystals are formed in all glasses and the size of NaNbO3 crystals decreases with the substitution of Al2O3 for SiO2. A crystallized (heat-treated at 684 °C for 5 h) glass with x = 5, which contains NaNbO3 nanocrystals with an average size of 50 nm, shows good optical transparency in the wavelength region of 500–2000 nm and a small hysteresis loop in the polarization–electric field curve. The lines containing NaNbO3 crystals were patterned on the surface of NiO-doped glass with x = 5 by irradiations (power: 1.3–1.4 W, scanning speed: 10 μm/s) of Yb:YVO4 fiber laser (wavelength: 1080 nm). The formation mechanism of NaNbO3 nanocrystals in aluminosilicate glasses was also discussed. 相似文献
95.
We propose a two-pulse excitation to efficiently form a novel sp(3)-bonded nanosize domain with frozen shear in a graphite crystal. This sp(3) structure is well stabilized by shear displacement between two neighboring graphite layers. The shearing motion is induced transiently by the first laser pulse, and is frozen by the second pulse before disappearing, resulting in the efficient formation of the sp(3)-bonded domain with frozen shear. We show this dynamical process qualitatively by molecular dynamics calculations. 相似文献
96.
Keiichiro Hironaka Toru Nagashima Susumu Ikeda Masanobu Azuma Kazuya Takada Hiroyuki Fukuyama 《Journal of Crystal Growth》2010,312(18):2527-2529
Aluminum nitride single crystal fabricated by a novel growth technique “pyrolytic transportation method”, which is advantageous for industrial process because of using α-Al2O3 as a source material instead of aluminum nitride, was characterized. This growth technique shows high growth rate up to 1.6 mm/h. High crystalline quality was indicated by X-ray topogragh and X-ray rocking curve. Full width at half maximum of (0 0 0 2) and (1 0 −1 0) were excellent values of 90 and 148 arcsec, respectively. Homoepitaxial overgrowth by hydride vapor phase epitaxy was successfully conducted. No dislocation was observed at the interface between the substrate and overgrowth layer by transmission electron microscopy. 相似文献
97.
Nobuyasu Hanari Nobuyasu Itoh Keiichiro Ishikawa Ryoko Iwasawa Yoshie Aoyagi Takashi Yarita 《International journal of environmental analytical chemistry》2013,93(6):692-705
A new calibration solution reference material for the determination of perfluorooctane sulfonate anion (PFOS) and its salts has been issued as a certified reference material (CRM) by the National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology (NMIJ/AIST). The purity amount-of-substance fraction of raw material potassium perfluorooctane sulfonate (K-PFOS) was evaluated based on the results obtained using the freezing point depression method, and the purity mass fraction of the raw material was calculated using the average molar mass of impurities, the molar mass of K-PFOS, and the purity amount-of-substance fraction. The certified concentration of this CRM was obtained by multiplying the dilution ratio of the raw material in a prepared solution (methanol) determined from the gravimetric blending method by the purity of the raw material. The preparation concentration of K-PFOS as a certified value of NMIJ CRM 4220-a was determined to be 9.93?mg?kg?1. In addition, the standard uncertainty of the certified value was evaluated from the purity evaluation as well as from sample inhomogeneity, instability, and preparation variation obtained from LC/MS measurements of different gravimetrically prepared solutions of the NMIJ CRM. Consequently, the expanded uncertainty was estimated to be 0.15?mg?kg?1 with a coverage factor k?=?2 corresponding to the half-width of estimated confidence interval of approximately 95%. 相似文献
98.
99.
A general concept for photoinduced structural phase transitions is developed in terms of the hidden multistability of the ground state and the proliferations of optically excited states. Taking the ionic→neutral (I - N) phase transition in the organic charge transfer crystal, TTF—CA, as a typical example for this type of transition, we, at first, theoretically show an adiabatic path of this transition, which starts from a single charge transfer exciton in the ionic phase, but finally reaches a neutral domain with a macroscopic size. In connection with this I—N transition, the concept of the initial condition sensitivity is also developed so as to clarify experimentally observed nonlinear characteristics of this material. In the next, using a more simplified model for the many-exciton system, we theoretically study the early time quantum dynamics of the exciton proliferation, which finally results in the domain formation of a large number of ex-citons. For this purpose, we derive a stepwise iterative equation to describe the exciton proliferation, and clarify the origin of the initial condition sensitivity. 相似文献
100.