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91.
92.
Imae T Hirota T Funayama K Aoi K Okada M 《Journal of colloid and interface science》2003,263(1):306-311
Binding of poly(amido amine) dendrimer to sodium hyaluronate (NaHA) in aqueous 0.25 M NaCl solution has been investigated by static light scattering. It was observed that the apparent weight-average molecular weight and the radius of gyration increase with the ratio of NH(2) terminal groups in the dendrimer to the carboxylate groups in the NaHA, [NH(2)]/[COO(-)]. Up to [NH(2)]/[COO(-)]=31, the observed variation of molecular weight was reproduced by the "average binding" model, where an average number of dendrimers binds to each NaHA chain. Based on the "critical binding" model, the maximum number, n(max), of dendrimers which can bind to a NaHA chain was calculated to be n(max)=300 for a solution of [NH(2)]/[COO(-)]=56. The obtained value corresponds to the binding of one dendrimer per 1.5 repeating units on a NaHA chain. It is suggested from the observed radius of gyration that, while the dendrimer-NaHA complexes of [NH(2)]/[COO(-)] up to 5 maintain a wormlike character similar to NaHA without bound dendrimers, those of [NH(2)]/[COO(-)] above 10 behave like rigid rods. It is concluded that the hydrogen-bonding interaction, besides the electrostatic interaction, should play an important role in the formation of the NaHA-dendrimer complexes. 相似文献
93.
Akutagawa T Shitagami K Nishihara S Takeda S Hasegawa T Nakamura T Hosokoshi Y Inoue K Ikeuchi S Miyazaki Y Saito K 《Journal of the American Chemical Society》2005,127(12):4397-4402
Nanoscale molecular rotors that can be driven in the solid state have been realized in Cs2([18]crown-6)3[Ni(dmit)2]2 crystals. To provide interactions between the molecular motion of the rotor and the electronic system, [Ni(dmit)2]- ions, which bear one S=1/2 spin on each molecule, were introduced into the crystal. Rotation of the [18]crown-6 molecules within a Cs2([18]crown-6)3 supramolecule above 220 K was confirmed using X-ray diffraction, NMR, and specific heat measurements. Strong correlations were observed between the magnetic behavior of the [Ni(dmit)2]- ions and molecular rotation. Furthermore, braking of the molecular rotation within the crystal was achieved by the application of hydrostatic pressure. 相似文献
94.
Hideo Sawada Tamikazu Narumi Atsushi Kajiwara Katsuya Ueno Kazuo Hamazaki 《Colloid and polymer science》2006,284(5):551-555
Fluoroalkyl end-capped oligomers reacted with tetraethoxysilane and silica/nanoparticles under alkaline conditions to afford
fluoroalkyl end-capped oligomers/silica nanoparticles (mean diameters: 31–54 nm) with a good dispersibility and stability
in organic media. Interestingly, the isolated fluorinated particle powders were found to afford nanometer size-controlled
colloidal particles with a good redispersibility and stability in these media. In addition, fluoroalkyl end-capped oligomers/silica
nanoparticles-encapsulated guest molecules such as stable organic radicals and ionic liquids were prepared under similar conditions.
These fluorinated nanoparticles-encapsulated guest molecules were applied to a new type of surface-modification agent, and
these particles were able to disperse well above the poly (methyl methacrylate) films. 相似文献
95.
Munehide Ishiguro Katsuya Nakaishi Tomo Nakajima 《Colloids and surfaces. A, Physicochemical and engineering aspects》2003,230(1-3):81-88
Acid rain is supposed to influence soil structures, because soils have pH-dependent charges. The adverse effects of acid rain on soils must be assessed. Although repulsive potential energy among soil clay particles generates swelling and dispersion, thereby changing the soil’s hydraulic conductivity, the relationship between hydraulic conductivity and repulsive potential energy has not been evaluated. Moreover, research into repulsive potential energy in multivalent counterionic systems has been rare. In this paper, repulsive potential energies for a volcanic ash soil (allophanic Andisol), which is characterized by a number of pH-dependent charges, were evaluated in a multivalent counterionic system. Changes in saturated hydraulic conductivity (K) of volcanic ash soil during dilute acid leaching and their relationship with the repulsive potential energies were examined. When nitric acid at pH 3 or 4 was leached, K decreased rapidly. On the other hand, the decrease in K attenuated as the proportion of sulfate in the dilute acid increased. Electrophoretic mobilities were measured and the zeta potentials were estimated. From the zeta potentials and the calculation of repulsive potential energies between the clay particles in the NO3–SO4 system, we concluded that the decrease in K for an acid solution with a high proportion of nitrate was due to swelling and dispersion of the soil induced by electrostatic repulsive potential energy. Because sulfate formed complexes on the clay surface, the repulsive potential energy decreased as the proportion of sulfate in the dilute acid increased. Then, the flocculation of the soil was maintained, thereby inhibiting the decrease in K. 相似文献
96.
Summary
Spectrophotometric Determination of Aluminium with Chromal Blue G in the Presence of Cetyltrimethylammonium Chloride
Chromal Blue G (C. I. 43835) in the presence of cetyltrimethylammonium chloride is proposed for the spectrophotometric determination of microgram amounts of aluminium. The stoichiometric ratio of aluminium to Chromal Blue G is 14. Beer's law is obeyed from 0.01 to 0.16 ppm of aluminium. The molar absorptivity is 1.62×1051·mole–1·cm–1 at 660 nm. 相似文献
97.
Duan Li Ou Pierre M. Chevalier Iain A. Mackinnon Katsuya Eguchi Ronald Boisvert Kai Su 《Journal of Sol-Gel Science and Technology》2003,26(1-3):407-412
Silicon containing materials have traditionally been used in microelectronic fabrication. Semi-conductor devices often have one or more arrays of patterned interconnect levels that serve to electrically couple the individual circuit elements forming an integrated circuit. These interconnect levels are typically separated by an insulating or dielectric film. Previously, a silicon oxide film was the most commonly used material for such dielectric films having dielectric constants (k) near 4.0. However, as the feature size is continuously scaling down, the relatively high k of such silicon oxide films became inadequate to provide efficient electrical insulation. As such, there has been an increasing market demand for materials with even lower dielectric constant for Interlayer Dielectric (ILD) applications, yet retaining thermal and mechanical integrity. We wish to report here our investigations on the preparation of ultra-low k ILD materials using a sacrificial approach whereby organic groups are burnt out to generate low k porous ORMOSIL films. We have been able to prepare a variety of organically modified silicone resins leading to highly microporous thin films, exhibiting ultra-low k from 1.80 to 2.87, and good to high modulus, 1.5 to 5.5 GPa. Structure property influences on porosity, dielectric constant and modulus will be discussed. 相似文献
98.
Yoshio Hamashima Sadao Yamamoto Tadatoshi Kubota Katsuya Tokura Koji Ishikura Kyogi Minami Fumihiko Matsubara Masaaki Yamaguchi Ikuo Kikkawa Wataru Nagata 《Tetrahedron letters》1979,20(51):4947-4950
Synthesis of optically active 3′-nor-type 1-oxacephems from 6-APA was described. -Nitrobenzyl 7β-amino-3-chloro-7α-methoxy-1-oxa-3-cephem-4-carboxylate was also prepared. 相似文献
99.
Reaction of the laterally lithiated (S)-4-isopropyl-2-(2-methoxy-6-methylphenyl)oxazoline with p-tolualdehyde gave an inseparable mixture of the addition products in low diastereoselectivity. However, the (S,S)-product cyclized to the corresponding 3,4-dihydroisocoumarin faster than the (S,R)-product on silica gel, which allowed to be produced both enantiomers of 8-methoxy-3-(p-tolyl)-3,4-dihydroisocoumarin in moderate to good optical purity [S-enantiomer: 75% ee; R-enantiomer: 96% ee]. This procedure was applied to the short-step synthesis of optically active 3,4-dihydroisocoumarin natural products such as (R)-8-hydroxy-3-(1-tridecyl)-3,4-dihydroisocoumarin and (R)-phyllodulcin. 相似文献
100.