Immunization strategies within managed care.
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Adolescent↗
Biomedical subjects
G Downs
Publications and source records attributed to G Downs.
Detection of resin acid compounds in airborne particulate generated from rosin used as a soldering flux.
Various uses of rosin and exposure to its resin acid constituents have been associated with dermal and pulmonary sensitization. Methodology is presented to detect resin acids common to rosin (such as abietic and dehydroabietic acid) found in aerosol from heated rosin flux. Air filtration, solvent filter extraction, and gas chromatography/mass spectrometry were used to provide qualitative and quantitative information on the resin acid content of aerosol produced during soldering with rosin flux. Abietic acid and dehydroabietic acid were identified and quantified in aerosol derived from heated rosin flux, in samples collected in the field and in laboratory generated samples. Other resin acids (including several apparently oxidized resin acids) were detected, but not quantified. Laboratory mass balance experiments using soldering temperatures and liquid rosin flux showed that much of the nonvolatile material originally present in unheated flux may be captured on a sampling filter following heating and aerosolization. The data presented suggest that resin acids are a major component (with regard to mass) of the airborne contaminants produced during soldering with rosin flux. Abietic acid was shown to be unstable on sampling filters held for a period of weeks, while dehydroabietic acid and total solvent-soluble material were not found to degrade under the same conditions. Rosin aerosol produced in the laboratory using a soldering iron and liquid rosin flux produced particles shown to be of respirable size using scanning electron microscopy.
Abietanes↗
Narrow polarized components in the OH 1612-MHz maser emission from supergiant OH-IR sources.
High-resolution OH 1612-MHz spectra are presented of the supergiant OH-IR sources VY CMa, VX Sgr, IRC 10420 and NML Cyg. The spectra have a resolution of 300 Hz. Narrow components in the spectra have linewidths as small as 550 Hz (0.1 km s-1) but there is no evidence for components narrower than this. These results are in accord with present understanding of maser line-narrowing and of the physical conditions in the OH maser regions. Many of the narrow components have an appreciable degree of circular polarization which is not apparent at the lower frequency resolutions usually employed. The circular polarization indicates the presence of magnetic fields of approximately 1 mG in the circumstellar envelopes, at distances of approximately 3x10(16) cm from the central stars. These fields are strong enough to influence the outflow from the stars, and may help to explain some of the asymmetries which are seen in their circumstellar envelopes.
Astronomical Phenomena↗