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221.
Ryoji Kobori Tomonori Ohba Takaomi Suzuki Taku Iiyama Sumio Ozeki Michio Inagaki Akihiro Nakamura Masato Kawai Hirofumi Kanoh Katsumi Kaneko 《Adsorption》2009,15(2):114-122
N2 adsorption isotherms of molecular sieve carbon were measured at 77 K and 303 K. The Ar adsorption isotherms of molecular
sieve carbon samples were also measured at 303 K. The grand canonical Monte Carlo (GCMC) simulation technique was applied
to calculate the N2 and Ar adsorption isotherms at 303 K using the ultramicropore volume determined by H2O adsorption. The comparative method of experimental and simulated isotherms of supercritical N2 and Ar at 303 K gave the width of the micropore mouth of the molecular sieve carbon, which can be applied to the ultramicropore
width determination for other noncrystalline porous solids. 相似文献
222.
Kenichi Murata Masato Suzuki Nobuhumi Nakamura Hiroyuki Ohno 《Electrochemistry communications》2009,11(8):1623-1626
The direct electron transfer reaction of fructose dehydrogenase (FDH) from Gluconobacter sp. on alkanethiol-modified silver nanoparticles (AgNPs) was examined using cyclic voltammetry and surface-enhanced resonance Raman scattering (SERRS). Using cyclic voltammetry, catalytic oxidation currents (based on the direct electron transfer reaction of FDH) were observed from a potential of approximately −100 mV (vs. Ag/AgCl, 3 M NaCl) in the presence of d-fructose, without a mediator. A comparison of the SERRS spectra and the resonance Raman spectra of FDH in solution indicated that the heme c site retained its six-coordinated low-spin heme after immobilization. Moreover, SERRS also demonstrated that the heme c of the adsorbed FDH was the electron transfer site within the enzyme. 相似文献
223.
Kenichi Murata Masato Suzuki Kazuki Kajiya Nobuhumi Nakamura Hiroyuki Ohno 《Electrochemistry communications》2009,11(3):668-671
The direct electron transfer reaction of fructose dehydrogenase (FDH) from Gluconobacter sp. on alkanethiol-modified gold nanoparticles (AuNPs) was examined. AuNP-modified electrodes were simply fabricated by depositing citrate-reduced gold nanoparticles onto a gold electrode and carbon fiber paper and then covering the surface with a self-assembled monolayer of alkanethiols. The immobilization of AuNPs provided a large effective surface area for the adsorption of FDH. Catalytic oxidation currents based on the direct electron transfer reaction of FDH were observed from a potential about ?100 mV (vs. Ag/AgCl, 3 M NaCl) in the presence of d-fructose without a mediator. The current density reached as high as 14.3 ± 0.93 mA/cm2 (at +500 mV), which was achieved in the presence of 200 mM d-fructose by immobilization of FDH on 2-mercaptoethanol-modified AuNP/carbon fiber paper electrodes. 相似文献
224.
Matsumoto T Furutachi H Kobino M Tomii M Nagatomo S Tosha T Osako T Fujinami S Itoh S Kitagawa T Suzuki M 《Journal of the American Chemical Society》2006,128(12):3874-3875
A discrete (mu-eta2:eta2-peroxo)Cu(II)2 complex, [Cu2(O2)(H-L)]2+, is capable of performing not only intramolecular hydroxylation of a m-xylyl linker of a dinucleating ligand but also intermolecular epoxidation of styrene via electrophilic reaction to the C=C bond and hydroxylation of THF by H-atom abstraction. 相似文献
225.
Ikeda M Tanaka Y Hasegawa T Furusho Y Yashima E 《Journal of the American Chemical Society》2006,128(21):6806-6807
We describe the construction of the first double-stranded metallosupramolecular helical polymers. We designed and synthesized a supramolecular duplex comprised of complementary m-terphenyl-based strands bearing a chiral amidine or achiral carboxylic acid together with two pyridine groups at the four ends. Supramolecular polymerization of the duplex with cis-PtPh2(DMSO)2 in 1,1,2,2-tetrachloroethane produced the double-stranded metallosupramolecular polymer with a controlled helicity of which the two complementary metallostrands are intertwined through the amidinium-carboxylate salt bridges. The structures and hydrodynamic dimensions of the metallosupramolecular polymers were characterized by 1H NMR, diffusion-ordered NMR, dynamic light scattering, absorption, and CD measurements. The polymeric structure was also visualized by atomic force microscopy. 相似文献
226.
Iwatsuki M Tomoda H Uchida R Gouda H Hirono S Omura S 《Journal of the American Chemical Society》2006,128(23):7486-7491
Two antimycobacterial agents, lariatins A and B, were isolated from the culture broth of Rhodococcus sp. K01-B0171. Their structures were elucidated by spectral analysis and advanced protein chemical methods to be unique cyclic peptides, which consist of 18 and 20 L-amino acid residues with an internal linkage between the gamma-carboxyl group of Glu8 and the alpha-amino group of Gly1. The three-dimensional structure of lariatin A deduced from NMR data by dynamical simulated annealing method indicates that the tail segment (Trp9-Pro18) passes through the ring segment (Gly1-Glu8) to form a 'lasso' structure. 相似文献
227.
Yamada H Kumauchi M Hamada N Zheng XG Park IH Masuda K Yoshihara K Tokunaga F 《Photochemistry and photobiology》2006,82(6):1422-1425
We report a unique lambdamax shift of the absorption maximum of a photoactive yellow protein (PYP) analogue reconstituted with a fluorinated chromophore (F-PYP). The difference in lambdamax between the free chromophore and the protein was significantly larger than that with the native chromophore. We concluded that the unusual lambdamax shift is caused by the electronegative character of the fluorine atom and not by steric hindrance. This result suggests that formation of a hydrogen bond between the fluorine atom and one or more amino acid residues could neutralize its electron-withdrawing character. The properties of analogues of PYP with brominated and methylated chromophore could be explained as an effect of steric hindrance. 相似文献
228.
Peikov V Sasai R Tanigawa M Petkanchin I Yamaoka K 《Journal of colloid and interface science》2006,295(2):445-456
Steady-state and decay birefringence, expressed in terms of the optical phase retardation per cell length delta/d, was measured on beta-FeOOH in aqueous ionic media at 633 nm and at 25 degrees C by an electric square-pulse technique over a wide range of field strength E to ca. 6 kV/cm. The field-strength dependence of both delta/d and field-free rotational relaxation time tau was determined at the sample concentrations between 0.0011 and 0.055 g/L and in the 0.02-2.0 mM NaCl concentration range. Extrapolation of both delta/d and tau values to infinitely high fields (E(2)-->infinity) could yield birefringence- and weight-average quantities, respectively. Observed tau values were decreased at weak fields but leveled off to ca. 0.3 ms at very high fields due to a slight polydispersity regarding the length and volume of particles. The weight-average relaxation time tau(w) was calculated with Perrin's expressions theoretically from the length, width, and volume of beta-FeOOH particles estimated in the dried state from electron micrograph. These quantities were variously averaged. The size distribution was discussed in terms of observed discrete histogram and theoretical (Weibull and Lansing-Kraemer) distribution functions. The sign of observed delta/d value was always positive. The infinitely high-field (delta/d)(infinity) values and the reduced optical anisotropy factor Delta g/n were evaluated by fitting to theoretical orientation functions. The intrinsic birefringence (n3-n1) could be estimated with the mean refractive index n(p) reported in the literature. For the spindle-shaped particle with an axial ratio of ca. 4, the sign of Delta g/n is always positive, whereas the quantity (n3-n1) was either negative (n(p) > 2.35) or positive (n(p) < 2.05) in sign or nearly zero (ca. n(p) = 2.26), depending critically on the n(p) values. 相似文献
229.
Huang H Okuno T Tsuda K Yoshimura M Kitamura M 《Journal of the American Chemical Society》2006,128(27):8716-8717
Goodwin-Lions-type sp2N/sp3N hybrid ligands R-BINAN-R'-Py possessing a C2 axis binaphthyl skeleton have been designed and synthesized. Combination of the new non-phosphine ligand with Ru(pi-CH2C(CH3)CH2)2(cod) has been revealed to catalyze the hydrogenation of aromatic ketones with high enantioselectivity of up to 99% ee. The reaction proceeds essentially without the need for any bases, but the reactivity is enhanced by the addition of KOt-C4H9 attaining an S/C ratio of up to 10 000. The success should expand the range of possibilities in designing catalysts not only for hydrogenation but also for many other reactions. 相似文献
230.
We have investigated the effects of grafted polymer chains [poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)] on the bending modulus and the intermembrane interactions of lamellar membranes (C(12)E(5) water) by means of a neutron spin-echo and a small-angle x-ray scattering technique. In this study the hydrophilic chain takes the mushroom configuration on the membrane. The bending modulus of the polymer-grafted membranes increases in proportion to the square of the end to end distance of the polymer chain, which agrees well with the theoretical prediction of Hiergeist and Lipowsky [J. Phys. II 6, 1465 (1996)]. From the interlamellar interaction point of view, the mushroom layer is renormalized to the membrane thickness, which enhances the repulsive Helfrich interaction. When the size of the decorated polymer chain increases to the interlamellar distance, however, the mushroom is squeezed so as to optimize the interlamellar potential. Further increase of the grafted polymer size brings a lamellar-lamellar phase separation, where the grafted polymer chains are localized in the dilute lamellar phase and the concentrated lamellar phase forms the onionlike texture. 相似文献