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671.
When two shear deformations γ1 and γ2 are successively applied to an entangled polymeric system, a composite temporary network is formed. In this article a simple method is proposed for evaluating separately the contributions from the component networks of different deformations, γ1 + γ2 and γ2, to the observed shear and normal stresses. The method is applied to literature data for a polystyrene solution. It is revealed that the entangled chain segments formed between the applications of two deformations relax very rapidly, while those formed prior to the first deformation do not relax for quite a long time. The result is in accord with the conjecture based on the tube model of entanglement that the chain ends lose their orientation as the chain creeps out of an oriented tube. 相似文献
672.
Y. Maki 《Journal of Radioanalytical and Nuclear Chemistry》1975,27(1):33-45
The separation and distribution of the chemical forms of131I produced from thermal neutron-irradiated tellurium compounds were investigated by thin-layer chromatography using alumina as adsorbent and water as developer as well as the effect of iodine carriers added on the distribution of different chemical forms of131I was studied. The effects of both atmospheric oxygen and light were investigated on the oxidation of carrier-free iodide on the thin-layer plate. 相似文献
673.
Kunihiro Osaki Shinichi Kimura Michio Kurata 《Journal of Polymer Science.Polymer Physics》1981,19(3):517-527
The shear stress σ, two components of birefringence, and extinction angle were measured for a concentrated polystyrene solution in step-shear deformation of magnitude of shear 0.3 ≤ γ ≤ 4.0. The stress-optical coefficient did not depend on either γ or time. The first and the second normal-stress differences v1 and v2 were evaluated with the use of the stress-optical law. Over a certain range of long times, σ could be factored as σ = γh(γ)G(t) and the quantity h(γ) agreed with the prediction of the Doi–Edwards theory based on the de Gennes tube model of entangled polymer chains. At short times the effect of γ on σ/γ was smaller than at long times. The relaxation spectrum became approximately independent of γ at the short-time end of the rubbery plateau region. The ratios v1/σ and v2/v1 were independent of time and were in quantitative agreement with those predicted by the Doi–Edwards theory: v1/σ was equal to γ, v2/v1 was negative, and |v2/v1| decreased with increasing γ. 相似文献
674.
Tony Masiello Engelene t.H. Chrysostom Arthur Maki Thomas A. Blake 《Journal of Molecular Spectroscopy》2004,223(1):84-95
Three fundamental modes and several hot bands of 34S18O3 have been investigated using both infrared spectroscopy and coherent anti-Stokes Raman scattering spectroscopy (CARS). Coriolis coupling effects are particularly noticeable in 34S18O3 due to the close proximity of the ν2 and ν4 fundamental vibrations, whose wavenumber values are 477.50864(5) and 502.05565(4) cm−1. The uncertainties in the last digits are shown in parentheses and are two standard deviations. Hot band transitions from ν2, ν4 levels give access to infrared inactive ν2, ν4 combination/overtone levels which interact strongly with levels of the Raman-active ν1 symmetric stretching mode due to indirect Coriolis couplings, l-resonances, and Fermi resonances. The result is a complex ν1 CARS Q-branch spectrum that is the most perturbed of the four SO3 isotopomers we have studied. The relative importance of these interaction terms on the ν1 CARS spectrum is examined in some detail and accurate rovibrational constants are determined for all of the mixed states, leading to deperturbed values of 1004.662(24), 0.0003503(9), and 0.0007066(12) cm−1 for ν1, α1B, and α1C, respectively. The Be value is found to be 0.310875(12) cm−1, which gives an equilibrium bond length re of 141.7339(3) pm, in excellent agreement with values of 141.7340(1) and 141.7347(7) pm reported earlier for 32S16O3 and 34S16O3. 相似文献
675.
The antisera using at final dilution of 1 : 10,000 have been prepared by immunizing synthetic human proinsulin connecting peptide to rabbits for human proinsulin C-peptide radioimmunoassay. The cross reactivities of human proinsulin C-peptide derivatives with the prepared antisera were reduced by leaving amino acid residues from N terminal, although this phenomenon was a little different among antisera. Those results suggested that main antigen determinant in N terminal 31-38 of human proinsulin connecting peptide. The cross reactivities of other animal proinsulin C-peptide and other peptide hormones with the prepared antissera were not recognized at 10(3) p mole/ml. 相似文献
676.
Pyrimido[5,4-]pteridine -oxide (1) oxidizes efficiently benzene, toluene, and anisole under UV irradiation to give the corresponding phenol derivatives 4, though the easiness of the reaction significantly depends upon the nature of the substituents on the benzene ring. 相似文献
677.
Heterodyne frequency measurements have been made on selected deuterium bromide 1-0 band transitions ranging from P(20) to R(17). Difference frequency beat notes between a tunablediode laser whose frequency was locked to the DBr absorption lines and a CO laser whose frequency was either locked or adjusted to a reference synthesized from CO2 laser frequency standards were measured. The beat note frequency was then combined with the measured CO laser frequency to give the DBr frequency. For two of the measurements, frequency-doubled CO2 laser radiation was substituted for the CO laser radiation. The measurements included electric quadrupole split triplets comprising the R(0) and P(1) transitions in the D79Br isotope. New DBr constants have been determined, and a table of frequencies is presented for the calibration of spectrometers and tunable lasers in the wavenumber range 1600 to 1990 cm?1. A table of far-infrared frequencies is also given for DBr covering the range from 50 to 206 cm?1. 相似文献
678.
Michio Kurata 《Journal of Polymer Science.Polymer Physics》1968,6(9):1607-1612
An approximate closed expression for the excluded volume effect of linear polymer molecules is developed with the aid of a uniform expansion model of perturbed chains. The linear expansion factor α for the end-to-end distance is given by (α3 ? 1) + (3/8) (α5 ? α3) = (5/2)z where z is the excluded volume parameter. This equation is numerically close to the Ptitsyn equation in the ordinary range of α; i.e., for 1 ≤ α ≤ 2. 相似文献
679.
680.