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161.
162.
Hisatoyo Morinaga Yusuke Ujihara Naho Yuto Daisuke Nagai Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2011,49(24):5210-5216
Metal‐free controlled ring‐opening polymerization of glycidyl phenyl ether (GPE) was achieved using tetra‐n‐butylammonium fluoride (Bu4NF) as an initiator in the presence of water and ethanol as chain transfer agents (CTAs). Number‐averaged molecular weight of poly(GPE) increased with an increase of [GPE]0/([Bu4NF]0 + [CTA]0) values, showing relatively narrow molecular weight distributions. NMR spectroscopic analysis exhibited a formation of ethoxy groups as well as FCH2 at the initiating polymer chain‐end when ethanol was used as the CTA in the polymerization. These results indicate that Bu4NF acts as a catalyst as well as the initiator for this polymerization system. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
163.
In this study, water penetration and the interaction between water and a pharmaceutical excipient in a tablet were investigated using near-infrared (NIR) spectroscopy and perturbation-correlation moving-window two-dimensional correlation spectroscopy (PCMW-2DCS). The penetration rate of water into a tablet was mainly dependent on the porosity of the tablet and was less dependent on the type of excipient. This behavior was well described by the Lucas–Washburn theory. The PCMW-2DCS technique revealed that there are two-staged interaction changes in NIR spectra of the water–powder interactions. The first and second changes corresponded to the water–solid interaction and the dissolution of the solid, respectively. The diffusion-controlled dissolution model by Nernst well explained these results. 相似文献
164.
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166.
Modern modeling approaches for circuit analysis lead to differential-algebraic equations (DAEs). The index of a DAE is a measure
of the degree of numerical difficulty. In general, the higher the index is, the more difficult it is to solve the DAE. The
index of the DAE arising from the modified nodal analysis (MNA) is determined uniquely by the structure of the circuit. Instead,
we consider a broader class of analysis method called the hybrid analysis. For linear time-invariant electric circuits, we
devise a combinatorial algorithm for finding an optimal hybrid analysis in which the index of the DAE to be solved attains
the minimum. The optimal hybrid analysis often results in a DAE with lower index than MNA.
相似文献
167.
168.
Takashi Kamimura Masaki Sato Takao Iwata 《Journal of magnetism and magnetic materials》1987,70(1-3):209-210
Transitions related to the spin-glass phase in Mn1−xTixSb
are revisited from the nonlinear ac susceptibility. Near the tricritical point (x≈0.8), the transition between ferromagnetic and reentrant spin-glass states is sharp. At x0.8, an anomally is found slightly above the temperature of usual spin-glass freezing. 相似文献
169.
170.
Hierarchical porous γ-alumina is successfully fabricated from a precursor solution consisting of surfactants, polystyrene
(PS) spheres, inorganic salts and solvents. After calcinations, uniform macropores are closely packed. The macropore size
coincides with the original PS sphere size. These macropores are connected by small windows. In addition, the macropore walls
have mesoporous structures, as confirmed by SAXS measurement and TEM observation. After calcination at 900 °C, the amorphous
alumina frameworks are converted to the crystallized γ-alumina phase. Even after crystallization, the existence of uniform
mesopores and high surface are well retained, though the mesoporous ordering is lower. 相似文献