Refractive Indices and Densities of H2O and CO(2) Films Condensed on Cryogenic Surfaces

Using an interference technique, the refractive index of both H(2)O and CO(2) films was determined at visible and near ir wavelengths as the gases were being condensed on a liquid nitrogen cooled surface. For these same films, the density was also measured. The results for the refractive index at a wavelength of 0.589 microm was 1.26 +/- 0.01 for H(2)O films and 1.43 +/- 0.01 for CO(2) films. The density of the H(2)O films was 0.81 +/- 0.02 g/cm(3), and for CO(2) films it was 1.67 +/- 0.03 g/cm(3).

Oxygen and the Ecology of Armillariella Elegans Heim

Oxygen is important in the ecology of A. elegans because it affects both the rate of growth and form ofrhizomorphs. Maximum growth is dependent on high rates of oxygen diffusion within the central canals of rhizomorphs but partial pressures of oxygen in excess of 0�04 atm in contact with the outside surfaces of rhizomorphs are inhibitory.

Effect on left ventricular performance of stimulation of an afferent nerve from muscle

The effect on left ventricular performance of electrical stimulation of the cut central end of the quadriceps nerve was studied in open-chest dogs. Stimulation of the nerve at 2 to 4 times threshold for the flexion reflex, which presumably activated intermediate-sized afferent fibers, caused a decrease in heart rate and arterial pressure. Stimulation at 5 to 25 times threshold, which presumably activated small-sized, high-threshold afferent fibers, increased heart rate, arterial pressure, and cardiac output. When heart rate, arterial pressure, and cardiac output were controlled, activation of high-threshold afferent fibers caused a significant increase in the maximal rate of pressure rise, stroke power, and mean rate of ejection of the left ventricle without an increase in the end-diastolic pressure. These same fibers may in some way be activated during muscular exercise and be partially responsible for the increase in left ventricular contractility that occurs during that time.

Isolation and Identification of Canthaxanthin from Micrococcus roseus

Cooney , J. J. (University of Dayton, Dayton, Ohio), H. W. Marks, Jr., and Anne M. Smith . Isolation and identification of canthaxanthin from Micrococcus roseus . J. Bacteriol. 92: 342–345. 1966.—The principal colored carotenoid of Micrococcus roseus was purified by solvent partitioning followed by column and thin-layer chromatography. Absorption spectra, partition coefficients, and infrared spectra suggested that the pigment was a diketo derivative of β-carotene. The pigment was subjected to reduction, and the reduced pigment was subsequently dehydrated. Spectral data and partition coefficients of these derivatives indicated that the original pigment was canthaxanthin (4′,4′-diketo-β-carotene). The pigment was an all- trans isomer; it does not exist as an ester in M. roseus . Canthaxanthin has not previously been identified as a bacterial pigment.