Detection limit estimated from slope of calibration curve: an application to competitive ELISA.

This paper theoretically derives a general rule that while the slope of the semi-logarithmic plot (Y vs. log X) of a calibration curve varies depending on analyte concentration, X, the slope takes a specific value at the detection limit (L(D)). This rule holds good irrespective of the shape of the calibration curve (linear or non-linear) and in this paper, is applied to competitive ELISA (enzyme linked immunosorbent assay). The following relationship is deduced: slope of log-dose B/B0 at L(D) = [relative standard deviation (RSD) of blank responses] / 0.13. The L(D) obtained from the above-mentioned slope corresponds to the dose at which the RSD of dose estimates is 0.3 (= 30%). A commercial kit for 17alpha-hydroxyprogesterone is taken as an example.     

Poly(γ-alkyl L-glutamates). II. Optical rotatory dispersion studies in organic solvents

Conformations of a series of poly(γ-alkyl L -glutamates) (ethyl, n-propyl, n-butyl, isobutyl, and isoamyl) were studied by ORD and infrared absorption methods. All except the n-propyl ester were found to be in helical form in nonpolar non-aromatic solvents such as ethyl acetate, chloroform, ethylene dichloride, methylene chloride, carbon tetrachloride, 2-chloroethanol, dimethylformamide, and dioxane. In such cases, the Cotton effects due to the n–π* transition of peptide bonds occurred near 234 mμ and were of a magnitude similar to those found for poly(γ-benzyl L -glutamate) and poly-L -methionine in nonpolar non-aromatic organic solvents. These four polypeptides in aromatic nonpolar solvents, such as benzene, benzyl alcohol, pyridine, and m-cresol, were also found to be in helical form, although the ORD parameters differed considerably from the values in non-aromatic solvents. An essential cause seems to be the interaction of π electrons on peptide bonds with π electrons in the solvents. Helix-coil transitions of these esters in chloroform-dichloroacetic acid mixtures (dichloroacetic acid seems to be a random coil-forming solvent) were expressed by the Shechter-Blout formulation. This was not true, however, for helix–coil transitions in benzyl alcohol–dichloroacetic acid mixtures. The dependence of the helical stability of these polypeptides in chloroform solution upon the side-chain length and upon temperature is discussed.     

Soluble magnesium and titanium catalyst components for ethylene polymerization

The catalyst system comprised of a heptane solution of magnesiumoctoate-H₂O-Tetrabutoxytitanium/diethylaluminumchloride was highly active for ethylene polymerization at a high temperature. High productivity for the catalyst system at a low temperature was achieved by the aging of the catalyst components. The effect of different orders of addition of the catalyst components on productivity was investigated to assume the role of each components in the formation of active species.     

Isothermal vapor-liquid equilibria for the binary systems propylene-carbon dioxide,propylene-ethylene and propylene-ethane at high pressure

isothermal vapor-liquid equilibria for the binary systems propylene-carbon dioxide, propylene-ethylene and propylene-ethane have been measured at 283.15 and 298.15 K using a static method.The equilibrium data obtained have been correlated with the total-pressure method using both the Redlich-Kwong equation of state modified by Soave and the perturbation equation proposed by Gubbins and Twu. From normal probability plots of the residuals in the correlations versus the theoretical residuals in the normal distribution, the applicability of each of these two equations has been tested statistically.Furthermore, the fugacity coefficients calculated from the virial equation have been compared with those obtained from the correlations for the low-pressure regions.     

Continuous hydrogenation reactions in a tube reactor packed with Pd/C

Continuous flow of the substrate solution and hydrogen gas through a tube reactor packed with Pd/C catalyst brings about a highly reactive and efficient hydrogenation system, which converts 4-cyanobenzaldehyde to the benzyl alcohol derivatives at 25 degrees C, and at 90 degrees C, the cyano group becomes reduced to give the corresponding amine and toluene derivatives within 2 min.