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141.
Dr. Jun Nakazawa Tomoaki Hori Prof. Dr. T. Daniel P. Stack Prof. Dr. Shiro Hikichi 《化学:亚洲杂志》2013,8(6):1191-1199
Immobilized nickel catalysts SBA*‐ L ‐x/Ni ( L =bis(2‐pyridylmethyl)(1H‐1,2,3‐triazol‐4‐ylmethyl)amine) with various ligand densities ( L content (x)=0.5, 1, 2, 4 mol % Si) have been prepared from azidopropyl‐functionalized mesoporous silicas SBA‐N3‐x. Related homogeneous ligand LtBu and its NiII complexes, [Ni( LtBu )(OAc)2(H2O)] ( LtBu /Ni) and [Ni( LtBu )2]BF4 (2 LtBu /Ni), have been synthesized. The L /Ni ratio (0.9–1.7:1) in SBA*‐ L ‐x/Ni suggests the formation of an inert [Ni L 2] site on the surface at higher ligand loadings. SBA*‐ L ‐x/Ni has been applied to the catalytic oxidation of cyclohexane with m‐chloroperbenzoic acid (mCPBA). The catalyst with the lowest loading shows high activity in its initial use as the homogeneous LtBu /Ni catalyst, with some metal leaching. As the ligand loading increases, the activity and Ni leaching are suppressed. The importance of site‐density control for the development of immobilized catalysts has been demonstrated. 相似文献
142.
Kawaguchi M Ito R Endo N Okanouchi N Sakui N Saito K Nakazawa H 《Journal of chromatography. A》2006,1110(1-2):1-5
A new method that involves liquid phase microextraction (LPME) with in situ derivatization and gas chromatography-mass spectrometry (GC-MS) is described for the determination of trace amounts of bisphenol A (BPA) in river water samples. The LPME conditions, such as the type of extraction solvent and the extraction time, are investigated. Then, the extract is directly injected into GC-MS. The detection limit and the quantification limit of BPA in river water sample are 2 and 10pgml(-1) (ppt), respectively. The calibration curve for BPA is linear with a correlation coefficient of >0.999 in the range of 10-10,000pgml(-1). The average recoveries of BPA in river water samples spiked with 100 and 1000pgml(-1) BPA are 104.1 (RSD: 8.9%) and 98.3 (RSD: 3.2%), respectively, with correction using the added surrogate standard, bisphenol A-(13)C(12). This simple, accurate, sensitive and selective analytical method may be applicable to the determination of trace amounts of BPA in liquid samples. 相似文献
143.
N. Tokoro S. Yamashita A. Igashira-Kamiyama J. Fujioka T. Konno Y. Nakazawa 《Journal of Thermal Analysis and Calorimetry》2010,99(1):149-152
A single crystal calorimetry of a heptacopper(II) complex of [Cu7(μ3-Cl)2(μ3-OH)6-(d-pen-disulfide)3] which has a double-cubane structure supported by d-penicillaminedisulfides has been performed at low-temperature region below 8 K. This compound is a metal complex which contains seven Cu(II)s in a cluster unit. These Cu(II)s are magnetically coupled each other by strong intra-complex interactions. The heat capacities under magnetic fields exhibit Schottky type anomalies explained by the Zeeman splitting of the doublet ground state of the complex. The g-value of the ground state is evaluated as 1.86 from the systematic analysis of the Schottky peak under magnetic fields. The first excited state of the cluster seems to be separated at least by several Kelvins, which is consistent with the theoretical calculations and magnetic susceptibility results. 相似文献
144.
A sensitive and selective method using liquid chromatography (LC)-electrospray mass spectrometry for the determination of growth promoters, trenbolone and zeranol, in bovine muscle and liver has been developed. The LC separation was performed on a Zorbax XDB-C18 column (150x2.1 mm I.D.) using 0.005% acetic acid-acetonitrile (60:40, v/v) as the mobile phase at a flow-rate of 0.2 ml/min. The positive ionization produced typical (M+H)+ molecular ions of alpha-trenbolone and beta-trenbolone. On the other hand, the negative mode produced (M-H)- ion of zeranol. The calibration graphs for alpha-trenbolone, beta-trenbolone and zeranol were rectilinear from 2.5 pg to 1.0 ng with selected ion monitoring. The drugs were extracted with 0.2% metaphosphoric acid-acetonitrile (6:4, v/v), and the extracts were cleaned up on a OASIS HLB (60 mg) cartridge. The recoveries of the hormones from bovine muscle fortified at 2 ng/g were 82.3-85.1%, and detection limits were 0.5 ng/g for each drug. 相似文献
145.
Yoshihiro Yoshimura John W. BrockTsunehisa Makino Hiroyuki Nakazawa 《Analytica chimica acta》2002,458(2):331-336
The purpose of this study is to establish an easy and accurate method for the determination of bisphenol A (BPA) in the human serum. The samples were applied to the C18 solid phase extraction (SPE) column for clean up of samples. The BPA is conjugated with tetrabutylammonium hydrogen sulfate as the counter ion in alkali solution. The ion paired BPA is moves from the aqueous phase to the organic phase as an ion paired extraction. BPA extracted from human serum were derivatized with pentafluorobenzyl bromide (PFBBr). The derivative was analyzed by gas chromatography (GC)/mass spectrometry (MS) using negative chemical ionization (NCI). The instrumental detection limit of BPA was 5 pg/ml (10 fg). The instrumental response between 0.01 and 100 pg/ml of BPA standards was linear (r2=0.998). The recovery of BPA spiked into human serum was 101.0±4.63 (1 pg/ml) and 100.9±3.75 (10 pg/ml), respectively. The concentration of BPA in the human serum from 20 individuals was 0.54 pg/ml. 相似文献
146.
Nakazawa Y Sagane Y Sakurai S Uchino M Sato H Toeda K Takano K 《Applied biochemistry and biotechnology》2011,165(7-8):1494-1506
Phospholipase D (PLD) catalyzes transphosphatidylation, causing inter-conversion of the polar head group of phospholipids and phospholipid hydrolysis. Previously, we cloned PLD103, a PLD with high transphosphatidylation activity, from Streptomyces racemochromogenes strain 10-3. Here, we report the construction of an expression system for the PLD103 gene using Streptomyces lividans as the host bacterium to achieve large-scale production. The phosphatidylcholine (PC) hydrolysis activity of S. lividans transformed with the expression plasmid containing the PLD103 gene was approximately 90-fold higher than that of the original strain. The recombinant PLD103 (rPLD103) found in the supernatant of the transformant culture medium was close to homogeneous. The rPLD103 was indistinguishable from the native enzyme in molecular mass and enzymatic properties. Additionally, rPLD103 had high transphosphatidylation activity on PC as a substrate in a simple aqueous one-phase reaction system and was able to modify the phospholipid content of soybean lecithin. Consequently, the expression system produces a stable supply of PLD, which can then be used in the production of phosphatidyl derivatives from lecithin. 相似文献
147.
Noriyuki Isobe Masahiro Sekine Satoshi Kimura Masahisa Wada Shigenori Kuga 《Cellulose (London, England)》2011,18(2):327-333
Cellulose-synthetic polymer nanocomposite films were prepared by immersion of cellulose gel in polymer solutions followed
by dry casting. The cellulose hydrogel was prepared from aqueous alkali-urea solution. As the synthetic polymer, polystyrene
(PS) and poly(methyl methacrylate) (PMMA) were used. The polymer content could be changed between 10 and 80% by changing polymer
concentration of immersing solution. While the mechanical properties of the cellulose-PMMA composite films showed a nearly
linear dependence on PMMA content, those of cellulose-PS composites showed an anomalous behavior; both tensile strength and
Young’s modulus showed prominent maxima at 15–30 wt% PS contents. This anomaly may have resulted from the specific interaction
between the aromatic ring of PS and the hydrophobic plane of the glucopyranoside. Both PMMA and PS composite films showed
significant improvements in dimensional thermal stability; up to 25 wt% synthetic polymer content, the coefficient of thermal
expansion (CTE) was as low as ca. 30 ppm/K, about 1/3 of the pure polymers. This indicates that the regenerated cellulose
network is effective in suppressing thermal expansion of the synthetic polymers. 相似文献
148.
Namiko Fukuzaki Kazuhiro Nakabayashi Satoshi Nakazawa Shigeaki Murata Tomoya Higashihara Mitsuru Ueda 《Journal of polymer science. Part A, Polymer chemistry》2011,49(1):93-100
A novel highly phosphonated poly(N‐phenylacrylamide) ( PDPAA ) with an ion‐exchange capacity (IEC) of 6.72 mequiv/g was synthesized by the radical polymerization of N‐[2,4‐bis(diethoxyphosphinoyl)phenyl]acrylamide ( DEPAA ), followed by the hydrolysis with trimethylsilyl bromide. Then, the crosslinked PDPAA membrane was successfully prepared by the electrophilic substitution reaction between the aromatic rings of PDPAA and the carbocation formed from hexamethoxymethylmelamine (CYMEL) as a crosslinker in the presence of methanesulfonic acid. The crosslinked PDPAA membrane had high oxidative stability against Fenton's reagent at room temperature. The proton conductivity of the crosslinked PDPAA membrane was 8.8 × 10?2 S/cm at 95% relative humidity (RH) and 80 °C, which was comparable to Nafion 112. Under low RH, the crosslinked PDPAA membrane showed the proton conductivity of 1.9 × 10?3 and 4.7 × 10?5 S/cm at 50 and 30% RH, respectively. The proton conductivity of the crosslinked PDPAA membrane lied in the highest class among the reported phosphonated polymers, and, consequently, the very high local concentration of the acids of PDPAA (IEC = 6.72 mequiv/g) achieved high and effective proton conduction under high RH. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010 相似文献
149.
S. Yamashita K. Hino Y. Inoue Y. Okada R. Hirahara Y. Nakazawa H. Miyasaka M. Yamashita 《Journal of Thermal Analysis and Calorimetry》2008,92(2):439-442
A magnetic-fields dependence of heat capacity of [Mn5(hmp)4(OH)2{N(CN)2}6]2MeCN·2THF (hmp=hydroxymethylpyridinate) is investigated by the thermal relaxation calorimetry technique. This compound is
a three-dimensional system consisting of Mn4 single-molecule magnet (SMM) units and Mn2+ ions, which are linked by the dicyanamide ligands to form a coordination network structure. A sharp peak of C
p being associated with the formation of three-dimensional long-range order is observed around 1.96 K. The thermodynamic discussion
based on the magnetic entropy suggests that both SMMs and Mn2+ ions are involved in the formation of the anitiferromagnetic spin ordering. However, this long-range ordering is very sensitive
to the external magnetic fields which work to change the magnitude of the Zeeman splitting of the SMM levels. The behavior
under magnetic fields is similar to that of the two-dimensional Mn4-network system studied previously. 相似文献
150.
Pisani C Itou M Sakurai Y Yamaki R Ito M Erba A Maschio L 《Physical chemistry chemical physics : PCCP》2011,13(3):933-936
The combination of new experimental and theoretical techniques provides evidence of instantaneous electron correlation effects in directional Compton profiles of crystalline silicon, which cannot be reproduced when reference is made to a density matrix obtained from a single-determinantal wavefunction. These effects are instead accounted for by a recently implemented post-Hartree-Fock periodic scheme, which gives results in quite good agreement with the high-quality experimental data. 相似文献