An investigation of the rheological relationships between shear stress shear rate apparent bulk viscosity temperature was carried out by examining the viscous flow of slightly milled native Hevea rubber (i) The Eisenschitz's equation for non-Newtonian flow has been verified by the experiments on the dependence of shear rate on shear stress. By this equation, the apparent viscosity can be referred to the Newtonian viscosity η_0 (at σ=0). The parameter (G_i=3.30×10~5 dynes/cm~2), interpreted as an internal...

An investigation of the rheological relationships between shear stress shear rate apparent bulk viscosity temperature was carried out by examining the viscous flow of slightly milled native Hevea rubber (i) The Eisenschitz's equation for non-Newtonian flow has been verified by the experiments on the dependence of shear rate on shear stress. By this equation, the apparent viscosity can be referred to the Newtonian viscosity η_0 (at σ=0). The parameter (G_i=3.30×10~5 dynes/cm~2), interpreted as an internal modulus of rigidity, was found to be practically independent of temperature in the range of 50-90℃, thus agreeing with the results by treating Saunder and Treloar's data. (ii) For the shear rate dependence of apparent viscosity, when the number of Khun segments per unit volume was taken into account for the calculation of retardation time τ_1=2.84η_0 [J_e]_∞, the Debye-Bueche's equation was found to be able to fit into our data at moderate low shear rates. The values of steady-state elastic compliance [J_e]_∞ were determined by elastic-recovery experiments. Furthermore, the internal shear modulus Gi could be thus calculated by combining the Eisenschitz's equation with the Debye-Bueche's one. (iii) From the experiments on the temperature dependence of viscous flow under various stresses, the apparent activation energy ΔE_η was found to be 12.7 kcal/mole; and therefrom, by estimation, the unit of flow-the Eyring segment would be 30 carbon atoms long. All determinations of the flow rate under constant stress were carried out in a Hppler parallel-plate plastometer, used as a viscoelasticity-rheometer according to the theory developed by Dienes.

β-Dichroine is one of the three alkaioids isolated by Chou et al. from Dichroa febrifuga Lour., a Chinese antimalarial herb. The antimalarial activity of this alkaloid has been shown to be 50 times that of quinine. Besides, many other aspects of the pharmacology of the dichroines have been described. This paper reports a method for the determination of β-dichroine in biological materials and the absorption, distribution, and excretion of this alkaloid in rats. The biological materials (tissue homogenates, blood,...

β-Dichroine is one of the three alkaioids isolated by Chou et al. from Dichroa febrifuga Lour., a Chinese antimalarial herb. The antimalarial activity of this alkaloid has been shown to be 50 times that of quinine. Besides, many other aspects of the pharmacology of the dichroines have been described. This paper reports a method for the determination of β-dichroine in biological materials and the absorption, distribution, and excretion of this alkaloid in rats. The biological materials (tissue homogenates, blood, urine, bile, and diluted faeces) were saturated with sodium chloride and extracted with chloroform at pH9. The chloroform layer was reacted with methyl orange reagent and the β-dichroine content deterined colorimetrically. This method was shown to possess a high degree of specificity for β-dichroine in tissues. Since normal excreta contains substances which behave similarly as β-dichroine, an eight-plate countercurrent distribution analysis was applied to study the excretion of the alkaloid. When given orally to rats,β-dichroine disappeared rapidly from the gastro-intestinal tract since one hour after a dose of 10 mg/kg only 58％ of the administered dose could be recovered from the GI-tract. However, about 30％ still remained four hours after administration of the drug. One hour after β-dichroine was given intravenously to a rat, the highest concentration was found in the kidneys. Moderate levels were found in the heart, spleen, liver, fat, and muscle, whereas very low levels were present in the blood. Only 16％ of an administered dose was excreted in the urine in a 24-hour period. Very little was excreted in the faeces and no β-dichroine was found in the bile.

In reference to a theorem proved by Sugawara and Kanazawa together with recent studies of asymptotic behaviour by Omnes, the subtration in the dispersion relations of Gi(t) and Ti,(t) is discussed. The contributions to the r,(t) and Fπ,(0 by the "far away" singularities are accounted for more carefully; the results so obtained seem to agree pretty well with both the electric and magnetic isotopic vector form factors; the Ti,(t) satisfies the requirement proposed by Vick from the analysis of π-N scattering...

In reference to a theorem proved by Sugawara and Kanazawa together with recent studies of asymptotic behaviour by Omnes, the subtration in the dispersion relations of Gi(t) and Ti,(t) is discussed. The contributions to the r,(t) and Fπ,(0 by the "far away" singularities are accounted for more carefully; the results so obtained seem to agree pretty well with both the electric and magnetic isotopic vector form factors; the Ti,(t) satisfies the requirement proposed by Vick from the analysis of π-N scattering data. Our calculation also shows that the total isotopic vector charge and magnetic moment are mainly due to the 2π intermediate state contribution; it is very probable that there exist no core point charge and magnetic moment at all.