Topological polymer chemistry: systematic classification of nonlinear polymer topologies.

Nonlinear polymer topologies composed of cyclic and branched polymer segments are systematically classified by reference to constitutional isomerism in a series of alkanes (CnH2n+2), monocycloalkanes (CnH2n), and polycycloalkanes (CnH2n-2, CnH2n-4, etc). Thus, the total number of chain ends (termini) and of branch points (junctions) are maintained as invariant parameters, as well as the number of branches at each junction and the connectivity of junction. On the other hand, the distance between two adjacent junctions and that between the junction and terminus are taken as variant parameters. On the basis of the classification of polymer topologies, a novel synthetic strategy by an "electrostatic self-assembly and covalent fixation" technique has been proposed to construct a variety of topologically unique polymer architectures.     

Effect of mirabilitum in formularization: change of prolyl endopeptidase inhibitory activity and of constituents using the preparation method of Tokaku-joki-to

To clarify the effect of Mirabilitum in formularization, change of prolyl endopeptidase inhibitory activity and of constituents using the preparation method of a Kampo formula Tokaku-joki-to ([Japanese characters: see text], Persia and Rhubarb combination) was examined by the liquid chromatography-mass spectroscopy (LC-MS) method. Mirabilitum under boiling condition caused qualitative and quantitative change of the constituents through hydrolysis which caused a change of its activity. This was considered to be the main reason the classical Chinese medical book "Shang han lun ([Japanese characters: see text])" specified that Mirabilitum should be added at a later stage of decoction.     

Electrical properties of calcia-doped ceria with oxygen ion conduction

The electrical conductivity of sintered specimens of (CeO₂)_1−x(CaO)_x was investigated by employing a standard four-probe dc technique as a function of temperature between 400°C and 900°C, composition from 0.10x0.80, and oxygen partial pressure from 10⁻¹⁸ to 1 atm. The temperature and composition dependence of the emf have been carried out with a concentration cell. X-ray diffraction studies indicated that a cubic fluorite crystal remained in all specimens studied, although the solubility limit of CaO in CeO₂ was assumed to lie close to 23 mol% from the change of the lattice constant. The magnitude of the conductivity decreased slightly with increase of the dopant concentrations up to x=0.50. The conductivity of these specimens was about 100 times larger than that of calcia-stabilized zirconia at 600°C with a smaller activation energies of 0.83–0.89 eV. With further increasing dopant concentrations, the magnitude of the conductivity was found to decrease remarkably. With an increase in the dopant concentration, the domain of primarily ionic conduction extended to a lower partial pressure. The conductivity of (CeO₂)_0.50(CaO)_0.50 was found to be primarily ionic down to 10⁻¹² atm even at 900°C. These results indicate that CaO-doped CeO₂ may be more an attractive candidate for fuel cells and other applications.     

Synthetic studies on β-lactam antibiotics. 13. Transformation of 6-epipenicillins to 2R-{(1S, 5R)-2-oxa-6-oxo-4,7- diazabicyclo[3.2.0]hept-3-en-7-yl}-3-methylbut-3-enoates

Reaction of 2β-unsubstituted or functionalized-methyl 6-epipenicillin sulfoxides $\text{2}$ with tervalent phosphorus compounds gave azetidinone-epi-oxazolines $\text{3}$, important intermediates in synthesis of 7α-methoxy-1-oxacephems. Preparation of the 2β-functionalized-methyl substrates is described also.     

Compact Branched Optical Waveguides Using High-Index-Contrast Stacked Structure

We have developed a novel branched optical waveguide using a stacked directional coupler, which consists of two Si₃N₄ core layers (each 0.3 μm thick) stacked with a thin (0.2 μm) SiO₂ film in between. Using this stacked high-index-contrast system, the size of the multiple branched waveguides can be dramatically reduced compared with the conventional Y-shaped branches. A four-branch optical waveguide is designed and fabricated, and good performance of distribution power of 25 ± 4% to each branch has been achieved.     

The Bando-Calabi-Futaki character and its lifting to a group character

 The Bando-Calabi-Futaki character of a compact K?hler manifold is an obstruction to the existence of K?hler metrics with constant scalar curvature, which is a generalization of the Futaki character of a Fano manifold. In this paper, we shall establish an interpretation of the Bando-Calabi-Futaki character as a secondary characteristic class. By using this interpretation, we shall also prove that the Bando-Calabi-Futaki character can be lifted to a group character. Received: 26 October 2000 / Revised version: 25 October 2001 / Published online: 16 October 2002 RID="★" ID="★" Partly supported by the Grant-in-Aid for Encouragement of Young Scientists (No. 09740047), The Ministry of Education, Science, Sports and Culture, Japan Mathematics Subject Classification (2000): 32Q20, 32Q15, 32M05, 57R30     

Site-specific phonon density of states discerned using electronic states

We have performed the measurement of the site-specific phonon densities of states (PDOS) discerned using electronic states. As far as we know, no general method could give the site-specific PDOS, although oscillating properties of the individual atoms in nonequivalent positions are not necessarily equivalent. However, the combination of the energy and time domain measurements of the nuclear resonant scattering of synchrotron radiation allows the identification of site-specific PDOS. We measured the site-specific PDOS of iron atoms in magnetite, which is a mixed valent compound, and the difference between partial phonon densities of the iron sites was clearly observed.     

Highly selective growth of vertically aligned double‐walled carbon nanotubes by a controlled heating method and their electric double‐layer capacitor properties

Vertically aligned double‐walled carbon nanotubes (DWCNTs) with the highest selectivity of 90% were synthesized by a controlled heating method and their electric double‐layer capacitor characteristics were evaluated. DWCNT arrays had a specific capacitance of 83 F/g, which is one of the highest values among CNT arrays in a nonaqueous solution and is almost equivalent to that for single‐walled CNT (SWCNT) arrays reported previously. At the same specific capacitance, DWCNTs with superior structural properties are more promising for practical capacitors than SWCNTs. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)