Mass balance studies of volatile chlorinated hydrocarbon phytoremediation

In field-scale mass balance studies of poplar remediation of carbon tetrachloride (CT), more than 95% of the mass of CT was degraded with all of the CT chlorine accountable as chloride ion accumulation in the soil. Atmospheric loss of CT through leaf transpiration and trunk diffusion was insignificant. These findings are consistent with previously reported uptake and degradation of trichloroethylene (TCE) by poplar. Poplar phytoremediation of CT and TCE results in little decrease in aqueous concentration, since water is taken up at about the same rate as the chlorinated compounds. From this result we predict that phytoirrigation--the application of pumped contaminated groundwater to planted systems--will result in concentrations of the pollutants at the bottom of the root zone that are higher than permitted regulatory levels. Such plantations will be susceptible to loss of contaminants during rainfall events, possibly resulting in pollution of uncontaminated soil. Greenhouse studies of pollutant profiles in the media beneath poplar trees that were surface irrigated with TCE and CT confirmed that regulatory concentrations of these pollutants were not achieved in the root zone of the poplar; rather concentrations fell by less than 50%.     

Optical rotatory dispersion of E. coli ribosomes and their constituents

Investigations have been made on the optical rotatory dispersion properties of E. coli ribosomes and their constituent RNA and proteins. The results indicate that (1) no conformational changes are involved in the formation of a 70S particle from the 50S and 308 subunits, (2) the E. coli ribosomal proteins are similar to most globular proteins with little α-helix content, and (3) the conformation of RNA and proteins inside the ribosome is very similar to that in the free state.     

The effect of temperature on the activity of (Naplus plus K plus)-ATPase

The marked temperature dependence of product formation by microsomal preparations of ouabain-sensitive (Na⁺ + K⁺)-ATPase prepared from rabbit renal cortex has been confirmed by extremely sensitive pH measurement. It was possible to confine measurements of H⁺ release to a change of less than 0.02 pH units. With periods of observation not exceeding 20 sec, the linearity of H⁺ release could be maintained. Below 14 ° there is no detectable H⁺ release which is sensitive to inhibition by 0.2 mm ouabain. Above this critical temperature, however, the reaction increases markedly throughout the range examined. The ouabain-insensitive or “residual” ATPase of these preparations also shows a dependence upon temperature, but only above a critical temperature of 24 °.     

Studies of Human Olfaction from the University of Pennsylvania Smell and Taste Center

This paper, presented in part as an invited lecture on the occasionof Professor E.P. Köster's retirement from Utrecht University,summarizes a large body of human studies performed at the Universityof Pennsylvania Smell and Taste Center during the last 17 years.Details of the development of standardized olfactory tests areprovided, including their validation and application in a widevariety of clinical and laboratory settings. Included are studiesrelated to transduction mechanisms in olfactory coding and factorsthat adversely influence olfactory function (e.g. age, gender,smoking, exposure to environmental chemicals, numerous diseases).A brief discussion of the strengths and weaknesses of the olfactoryvector hypothesis for neurodegenerative diseases is also presented.Chem. Senses 22: 565–586, 1997.