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81.
Tomohiro Narukawa Takayoshi Kuroiwa Izumi Narushima Koichi Chiba 《Analytical sciences》2008,24(3):355-360
The sensitivity of graphite furnace atomic absorption spectrometry (GFAAS) to arsenobetaine (AB) was 1.3-times higher than to inorganic As. In order to understand the mechanism underlying this observation, the atomization processes for both chemical species were investigated in terms of the enthalpy change (DeltaH) during the atomization process in GFAAS. The enthalpy change of AB was slightly lower than that of inorganic As, which suggested that AB was atomized more efficiently than was inorganic As. Moreover, it was observed that some co-existing organic materials enhanced the analytical sensitivity of inorganic As. The sensitivity difference between inorganic As and AB depended upon the mechanisms of their atomization processes. 相似文献
82.
Akio Tsuboi Petr Kol Takeshi Ishikawa Yoshinori Kamiya Hirokatsu Masuoka 《Journal of Polymer Science.Polymer Physics》2001,39(12):1255-1262
The sorption of C2 and C3 hydrocarbons in two ethylene–propylene copolymers and a propylene homopolymer and the simultaneous dilation of the polymers were measured at temperatures of 287–363 K and pressures up to 4 MPa. The sorption isotherms were well described by the Flory–Huggins theory of dissolution. Dilation isotherms in the form of elongation versus pressure were similar in shape to the corresponding sorption isotherms. Solubility coefficients, partial molar volumes, and Flory–Huggins interaction parameters were determined from these isotherms. The thermal expansivities of the hydrocarbons dissolved in the polymers were 0.002–0.005 K?1, and the Flory–Huggins interaction parameters depended not only on temperature but also on concentration. At 323 K, the calculated solubilities of propylene in the ethylene–propylene‐rubber regions of the copolymers were 1.8 times higher than in the amorphous regions of the propylene homopolymer. © 2001 John Wiley & Sons, Inc. J Polym Sci Part B: Polym Phys 39: 1255–1262, 2001 相似文献
83.
Yutaka Nishigaichi Ken-ichi Tamura Narifumi Ueda Hidetoshi Iwamoto Akio Takuwa 《Tetrahedron letters》2008,49(13):2124-2127
Using a single allyltin reagent with a chiral nitrogen functionality, binary and remote asymmetric induction was realized toward various aldehydes. Either syn- or anti-1,4-amino-alcohols were selectively obtained with the use of Yb(OTf)3 or SnCl4, respectively. The structures of both diastereomers were identified by means of X-ray analysis. 相似文献
84.
85.
Sorbitol was readily converted by heating in hydrophobic ionic liquids by the presence of ion exchange resins. Chemoseletivity of the dehydration depended on the choice of ion exchange resin; Nafion selectively produced isosorbide while Amberlite gave 1,5-anhydrosorbitol along with unreacted sorbitol. Ionic liquids used in the reaction were readily recovered by simple extraction procedure. With these procedures, we succeeded to prepare isosorbide in pure form, not contaminated with either ionic liquids or acid catalyst, by simple experimental procedure. 相似文献
86.
Akio Saito 《Tetrahedron letters》2010,51(17):2247-3204
PIDA [phenyliodine(III) diacetate] in AcOH or AcOH-HFIP (hexafluoroisopropanol) efficiently promotes the formation of 2,5-disubstituted oxazoles via the oxidative cycloisomerization of propargylamide derivatives. 相似文献
87.
Protein dynamics evolves in a high-dimensional space, comprising aharmonic, strongly correlated motional modes. Such correlation often plays an important role in analyzing protein function. In order to identify significantly correlated collective motions, here we employ independent subspace analysis based on the subspace joint approximate diagonalization of eigenmatrices algorithm for the analysis of molecular dynamics (MD) simulation trajectories. From the 100 ns MD simulation of T4 lysozyme, we extract several independent subspaces in each of which collective modes are significantly correlated, and identify the other modes as independent. This method successfully detects the modes along which long-tailed non-Gaussian probability distributions are obtained. Based on the time cross-correlation analysis, we identified a series of events among domain motions and more localized motions in the protein, indicating the connection between the functionally relevant phenomena which have been independently revealed by experiments. 相似文献
88.
Tomohiro Narukawa Takayoshi Kuroiwa Izumi Narushima Yasujiro Jimbo Toshihiro Suzuki Koichi Chiba 《Analytical and bioanalytical chemistry》2010,397(2):493-499
Arsenate [As(V)] solution reference material, National Metrology Institute of Japan (NMIJ) certified reference material (CRM)
7912-a, for speciation of arsenic species was developed and certified by NMIJ, the National Institute of Advanced Industrial
Science and Technology. High-purity As2O3 reagent powder was dissolved in 0.8 M HNO3 solution and As(III) was oxidized to As(V) with HNO3 to prepare 100 mg kg-1 of As(V) candidate CRM solution. The solution was bottled in 400 bottles (50 mL each). The concentration of As(V) was determined
by four independent analytical techniques—inductively coupled plasma mass spectrometry, inductively coupled plasma optical
emission spectrometry, graphite furnace atomic absorption spectrometry, and liquid chromatography inductively coupled plasma
mass spectrometry—according to As(V) calibration solutions, which were prepared from the arsenic standard of the Japan Calibration
Service system and whose species was guaranteed to be As(V) by NMIJ. The uncertainties of all the measurements and preparation
procedures were evaluated. The certified value of As(V) in the CRM is (99.53 ± 1.67) mg kg-1 (k = 2). 相似文献
89.
The matrix-isolation infrared spectrum of a thermally evaporated ionic liquid, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([Emim][OTf]), was measured by FTIR spectroscopy and analyzed with the aid of DFT calculations. The main chemical species in the observed IR spectrum was mainly identified as the 1:1 cation-anion pair, which corresponds to the second stable ion-pair structure bonded through five hydrogen bonds between three O atoms of the anion side and four H atoms of the cation. 相似文献
90.
Yoichi Shibusawa Atsushi Shoji Chihiro Suzuka Akio Yanagida Yoichiro Ito 《Journal of chromatography. A》2010,1217(20):3457-3460
Nucleic acid constituents such as nucleobases, nucleosides and nucleotides were separated by counter-current chromatography using type J coil planet centrifuge. The separation was performed with a hydrophilic solvent system composed of 1-propanol/800 mM potassium phosphate buffer (pH 7.4) (1:1, v/v) by eluting the lower aqueous phase at a flow-rate of 0.5 ml/min. Eight selected nucleic acid constituents (4.0 mg, 0.5 mg of each), uridine monophosphate (UMP), adenosine monophosphate (AMP), deoxyadenosine monophosphate (dAMP), uridine, urasile, deoxy uridine, adenosine and adenine were well resolved within 160 min. 相似文献