Two‐dimensional polymer synthesis through the topochemical polymerization of alkylenediammonium muconate as a multifunctional monomer

Here we demonstrate a unique two‐dimensional polymer synthesis through topochemical polymerization via polymer crystal engineering, which is useful for controlling and designing the polymerization reactivity as well as the polymer chain and crystal structures. We have succeeded in the synthesis of a sheet polymer through the polymerization of alkylenediammonium (Z,Z)‐muconate as a multifunctional 1,3‐diene monomer in the crystalline state under the irradiation of UV and γ‐rays or upon heating in the dark. The photopolymerization reactivity of several muconates and the structural control of the obtained polymer are described. The stereochemical structure of the polymer and the polymerization mechanism are discussed on the basis of the results of IR and NMR spectroscopy, thermogravimetric measurements, and solid‐state hydrolysis for the transformation into poly(muconic acid). © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 3922–3929, 2004     

Novel synthesis of 7-fluoro-8-(trifluoromethyl)- 1H-1,6-naphthyridin-4-one derivatives: intermolecular cyclization of an N-silyl-1-azaallyl anion with perfluoroalkene and subsequent intramolecular skeletal transformation of the resulting pentasubstituted pyridines

In this study, fluorine-containing pentasubstituted pyridine derivatives 9a-m were prepared regioselectively in good yields by the intermolecular cyclization of a variety of N-silyl-1-azaallylic anion intermediates 7, which were generated from a functionalized silane 5 and an aromatic/aliphatic nitrile 6 with perfluoroalkene 8. Also, 7-fluoro-8-(trifluoromethyl)-1H-1,6-naphthyridin-4-one derivatives 11a-k were synthesized in excellent yields by the subsequent base-promoted intramolecular skeletal transformation of the resulting pyridine derivatives 10a-k.     

The instrument accuracy limit for objectively measuring the loudness rating of telephone systems

This paper investigates a sensitivity measurement method for carbon transmitters and a calculation method for the loudness rating of a telephone system. The sensitivity varies depending on the artificial voice used for the measurement and the conditioning procedures. The most preferable methods for obtaining values which coincide with those in the subjective loudness rating test are discussed. With respect to the loudness calculation method, the algorithm, parameter values, ear leakage loss, and voice spectrum are discussed. As a result of these investigations, the deviation between the objective and subjective rating is found to be 0.7 dB for the various types of handset telephones when the measurement conditions are optimized. This deviation is considered to be the limit of measurement accuracy. The performance of currently developed objective measurement instruments is close to this limit. Considering the fluctuations accompanying repetitive subjective measurements, the objective rating corresponds satisfactorily with the subjective rating.     

Preparation of new nitrogen-bridged heterocycles. 51. Syntheses and structures of compounds having two indolizine nuclei in a molecule.

New compounds having two indolizine nuclei in a molecule were prepared in low to moderate yields from the reactions of potassium 2-indolizinethiolates with 1,omega-dihalides such as 1,2-diiodoethane, 1,3-dibromopropane, 1,4-dibromobutane, alpha,alpha'-dichloro-o-xylene, and alpha,alpha'-dichloro-p-xylene. Most of the products had the conformation in which the two indolizine rings in the molecule are as remote as possible, but only 1,2-bis[[(2-indolizinyl)thio]methyl]benzene derivatives, prepared from potassium 2-indolizinethiolates and alpha,alpha'-dichloro-o-xylene, showed a weak attractive interaction between the two indolizine nuclei in the X-ray analysis and the nuclear Overhauser and exchange spectroscopy (NOESY) spectrum.     

Exact Absorption Probabilities for the D3-Brane

We consider a minimal scalar in the presence of a three-brane in ten dimensions. The linearized equation of motion, which is just the wave equation in the three-brane metric, can be solved in terms of associated Mathieu functions. An exact expression for the reflection and absorption probabilities can be obtained in terms of the characteristic exponent of Mathieu's equation. We describe an algorithm for obtaining the low-energy behavior as a series expansion, and discuss the implications for the world-volume theory of D3-branes.