Biospinning: Change of water contents in drawn silk

Changes of the water content in drawn silk during drying were investigated by thermal analysis and ¹H pulse NMR. Water in liquid silk by drawing extruded from the inside of the silk filament into ambient air. The water contents in the drawn silk decreased with drying time. Assuming the nonfreezing water has a concentration of 10 wt % in the liquid silk, the percentage distribution of water in liquid silk is composed of 10 wt % nonfreezing water, 40 wt % freezing water, and 30 wt % free water. This 40 wt % freezing water in the liquid silk may be important for the formation of fine pores on the surface of drawn silk. The apparent pore radius, which was calculated from the results of thermal analysis, on the surface of drawn silk decreased to 5.0 nm and finally to 2.0 nm. The calculated apparent fine pore formed on the surface by drawing was 4.0 nm. © 2002 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 274–280, 2003     

Low Loss Polarization Maintaining Photonic Crystal Fiber

A low loss polarization maintaining photonic crystal fiber has been fabricated. The fiber loss was 1.3 dB/km at 1550 nm. The polarization crosstalk for a 100-m fiber was ?5 dB at 1550 nm.     

Conversion of disilanes to functional monosilanes: XII. The palladium(0)-catalyzed dechlorinative silylation of benzylic chlorides with methylchlorodisilanes. A facile route to benzylmethylchlorosilanes

This paper describes the facile dechlorinative silylation of benzylic chlorides of types XC₆H₄CH₂Cl (X = H, Me and Cl) and ClCH₂C₆H₄CH₂Cl (o-, m- and p-isomers) with methylchlorodisilanes ClMe₂SiSiMe₂Cl, ClMe₂SiSiMeCl₂ and Cl₂MeSiSiMeCl₂ in the presence of Pd(PPh₃)₄ to give the corresponding benzylmethylchlorosilanes in good to high yields.     

Kinetic analysis of photopolymerization reaction of lauryl acrylate with a photoinduced chemical reaction calorimeter

Calorimetric studies on kinetics of photopolymerization reactions made previously have been limited by the structures of the calorimeters. This report suggests a thermal-leak type of calorimeter for carrying out kinetic analysis of the photopolymerization reaction. The method was applied to the photopolymerization system consisting of lauryl acrylate and benzoin methyl ether. The results obtained illustrate the utility of this apparatus.     

On the accelerated iterative method for estimating the optimum overrelaxation parameter

This paper is concerned with the iterative method for estimating the optimum overrelaxation parameter. The improved power method (IP method) with the greatest rate of convergence is derived and compared with the Chebyshev polynomial iterative method (CP method) and the other iterative methods. Two algorithms (algorithms A and B) based on the IP method are presented. Some numerical results are shown.     

A new synthesis of deglyco-bleomycin A2 aiming at the total synthesis of bleomycin

An improved route to synthesize deglyco-bleomycin A2, the aglycon of bleomycin A2, aiming at the total synthesis of bleomycin is described. The new route is characterized by the stepwise elongation of the amino acid constituents and the use of a thiol ester obtained by aldol condensation.     

Chlorine distribution and structure–property relationship of chlorinated polypropylene

High-resolution proton magnetic resonance (PMR) spectroscopy was used to determine the chlorine distribution of chlorinated polypropylenes in 1,1,2,2,-tetrachloroethane solution and suspension (5–25 wt % chlorine). The determination is based on measuring the relative amounts of methyl and methylene groups which are α, β, and γ to chlorinecontaining groups in chlorinated polypropylenes. The results obtained from the 100 MHz and 220 MHz PMR spectrometers were compared with the theoretical predictions provided by Frendsdorff and Ekiner, based on the statistics of substitution polymers. Furthermore, the PMR data were correlated with infrared and differential scanning calorimetry data to obtain the structural and crystalline properties. The comparison showed that the suspension-chlorinated polypropylenes show structure heterogeneity and thermal instability, whereas polymers chlorinated in solution with gaseous chlorine show a random chlorine distribution and thermal stability compared with the former.