Horst W. Hoyer

Diffusion coefficients of cadmium tagged sodium alkyl sulfate micelles—polarographic, electromotive force, and monolayer studies

Abstract By tagging micelles with a cation which is reducible at a dropping mercury electrode a new method for measuring diffusion coefficients has been developed. This method was applied to the determination of the diffusion coefficients of sodium decyl, dodecyl, and tetradecyl sulfate micelles, using Cd++ as a label, giving values of 1.46 × 10−6, 0.76 × 10−6, 0.48 × 10−6cm2/sec, respectively, for these substances. The interactions between the cadmium and the micelle were investigated by doing a monolayer study of the interaction of Cd++ on a spread long-chain sodium sulfate (C20SO4Na). It was found that the Cd++ ions were probably concentrated in the surface region. The activity of a constant amount of Cd++ ions in a varying amount of sodium dodecyl sulfate was studied by measuring the emf of the following cell: Cd electrode//electrolyte//AgCl/Ago. The Cd++ ion concentration left in solution in the presence of micelles is so small that the assumption that all the Cd++ ions are on the surface of the micelle is justified. It is concluded that the polarographic determination of diffusion coefficients of long-chain alkyl sulfate micelles by tagging them with Cd++ ions is valid.

Differential scanning calorimetry studies on the dehydration of deoxyribonucleic acid and polyadenylic acid

Abstract Differential scanning calorimetry (DSC) experiments have been carried out on the desorption of water from polyadenylic acid and deoxyribonucleic acid in the region of less than 10 water molecules per monomer unit. The enthalpy of the desorption process increases from a value essentially that of the vaporization of liquid water to approximately 16,000 cal per mole as the quantity of absorbed water decreases from 10 to 2 water molecules per monomer unit. Equilibrium vapor pressure studies together with the DSC measurements on polyadenylic acid permit calculation of the entropy of the absorbed water as essentially that of liquid water.

Differential Thermal Analysis of Rapid High Pressure Decompositions

Abstract A simple sample handling technique for recording differential thermograms of volatile and/or high pressure producing compounds is described. The calculation of activation energies for several hydrazines and explosives is reported.

Three-Dimensional Perception of Planar Line Segments:

Two-dimensional line drawings can be perceived as three-dimensional images if they are viewed through a grating of parallel lines placed a short distance above the drawing. The position in space of the images is a function of the angle between the lines in the drawing and those in the viewer grating.

Differential thermal analysis with capillary tubes

ZusammenfassungEin Verfahren zur Durchführung von Differential-Thermoanalysen in verschlossenen Kapillarröhrchen wurde beschrieben, womit Aktivierungsenergien und andere kinetische Daten für thermisch induzierte Reaktionen ermittelt werden künnen. Proben von 2 bis 4 mg werden verwendet. Die Ergebnisse entsprechen denen, die mit dem kürzlich beschriebenen Makrosystem ermittelt wurden.