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1.
Katsunari Inoue Kazuaki Kato Norimitsu Tohnai Mikiji Miyata 《Journal of polymer science. Part A, Polymer chemistry》2004,42(18):4648-4655
We studied simulations by computer graphics to estimate the steric mechanism of the asymmetric polymerization of prochiral diene monomers in channels of inclusion compounds of steroidal bile acids, such as deoxycholic acid (DCA) and cholic acid. We applied a hierarchization method to interpret the crystal structures of bile acids, clarifying that the chiral host molecules associated to form characteristic 21-helical assemblies with uneven surfaces. A detailed analysis of the uneven channels in a close-packing state indicated that there were many possible arrangements of the monomers in the channels. The plausible arrangements in the channel could explain a previous study, which showed that the polymerization in the DCA channel yielded chiral polymers with a predominant configuration from prochiral diene monomers, such as 2-methyl-trans-1,3-pentadiene. On the basis of such simulation studies of the arrangements of guest monomers in the channel, we examined a plausible steric mechanism for asymmetric inclusion polymerization. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4648–4655, 2004 相似文献
2.
Hiroaki Miyagawa Michael J. Rich Lawrence T. Drzal 《Journal of Polymer Science.Polymer Physics》2004,42(23):4391-4400
The thermophysical and mechanical properties of a nanocomposite material composed of amine‐cured diglycidyl ether of bisphenol A (DGEBA) reinforced with organomontmorillonite clay are reported. The storage modulus at 100 °C, which was above the glass‐transition temperature (Tg), increased approximately 350% with the addition of 10 wt % (6.0 vol %) of clay. Below the Tg, the storage modulus at 30 °C increased 50% relative to the value of unfilled epoxy. It was determined that the Tg linearly increased as a function of clay volume percent. The tensile modulus of epoxy at room temperature increased approximately 50% with the addition of 10 wt % of clay. The reinforcing effect of the organoclay nanoplatelets is discussed with respect to the Tandon–Weng and Halpin–Tsai models. A pseudoinclusion model is proposed to describe the behavior of randomly oriented, uniformly dispersed platelets in nanocomposite materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4391–4400, 2004 相似文献
3.
The effect of α‐cyclodextrin (α‐CD) on the crystallization behavior of poly(3‐hydroxybutyrate) (PHB) was investigated with polarized optical microscopy, differential scanning calorimetry, and wide‐angle X‐ray diffraction. We found that the addition of α‐CD can greatly accelerate the crystallization of PHB and that α‐CD has a potential not only to enhance the nucleation but also to accelerate the crystallization of PHB. Compared to a conventional nucleation agent, such as talc, α‐CD is a natural product and has many advantages because it is environmentally friendly and safe to humans. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3461–3469, 2004 相似文献
4.
Takashi Yoshitake Ryuji Iizuka Kaoru Fujino Osamu Inoue Kenji Yamagata Hitoshi Nohta Masatoshi Yamaguchi 《Analytical sciences》2004,20(12):1687-1690
An improved high-performance liquid-chromatographic (HPLC) assay for the simultaneous determination of serotonin (5-HT) and 5-hydroxyindole-3-acetic acid (5-HIAA) in human urine is reported. Following the automated precolumn derivatization of urinary 5-HT and 5-HIAA with benzylamine, the derivatives are separated by isocratic elution on a reversed-phase C18 semi-microbore column, and are fluorometrically detected at an excitation wavelength of 345 nm and an emission wavelength of 480 nm. The detection limits of 5-HT and 5-HIAA are 7 and 5 nmol/l in urine (0.7 and 0.5 fmol/20-microl injection). The proposed automatic method permits a highly selective and sensitive determination of 5-HT and 5-HIAA in human urine without any sample purification. 相似文献
5.
6.
Hiroaki Mukaidani 《Journal of Mathematical Analysis and Applications》2004,300(1):17-29
The guaranteed cost control problem via the decentralized robust control for nonlinear uncertain large-scale systems that have delay in both state and control input is considered. Sufficient conditions for the existence of guaranteed cost controllers are given in terms of linear matrix inequality (LMI). It is shown that the decentralized local state feedback controllers can be obtained by solving the LMI. 相似文献
7.
8.
9.
Tomohiro Kyotani Sonoko Kakui Takehito Mizuno Naoto Shimotsuma Soushi Inoue Junji Saito 《Analytical sciences》2006,22(7):1031-1034
A zeolite NaA (LTA) membrane supported by an alumina porous support tube for pervaporation (PV) dehydration of ethanol was characterized by transmission electron microscopy (TEM) using a focused ion beam (FIB) thin-layer specimen preparation technique and by Fourier transform infrared attenuated total reflectance method (FTIR-ATR) using a diamond prism as the waveguide. FIB-TEM clearly presented cross-section images up to about 15 microm depth from the membrane surface. FTIR-ATR monitored the Si-O asymmetric stretching vibration spectrum. The Si-O spectrum was compared with the TEM image and their relationships were discussed. By combining the two methods, we could study the thickness of surface LTA crystals, the grain boundary, the LTA/alumina interface structure and the crystallinity and density of materials inside of the alumina porous support. Consequently, fine structure changes of the LTA membrane corresponding to the hydrothermal synthesis condition could be sensitively detected. 相似文献
10.
Multiderivations of Coxeter arrangements 总被引:3,自引:0,他引:3
Hiroaki Terao 《Inventiones Mathematicae》2002,148(3):659-674
Let V be an ℓ-dimensional Euclidean space. Let G⊂O(V) be a finite irreducible orthogonal reflection group. Let ? be the corresponding Coxeter arrangement. Let S be the algebra of polynomial functions on V. For H∈? choose α
H
∈V
* such that H=ker(α
H
). For each nonnegative integer m, define the derivation module D
(m)
(?)={θ∈Der
S
|θ(α
H
)∈Sα
m
H
}. The module is known to be a free S-module of rank ℓ by K. Saito (1975) for m=1 and L. Solomon-H. Terao (1998) for m=2. The main result of this paper is that this is the case for all m. Moreover we explicitly construct a basis for D
(m)
(?). Their degrees are all equal to mh/2 (when m is even) or are equal to ((m−1)h/2)+m
i
(1≤i≤ℓ) (when m is odd). Here m
1≤···≤m
ℓ are the exponents of G and h=m
ℓ+1 is the Coxeter number. The construction heavily uses the primitive derivation D which plays a central role in the theory of flat generators by K. Saito (or equivalently the Frobenius manifold structure
for the orbit space of G). Some new results concerning the primitive derivation D are obtained in the course of proof of the main result.
Oblatum 27-XI-2001 & 4-XII-2001?Published online: 18 February 2002 相似文献