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Biomedical subjects

R M Bethea

Publications and source records attributed to R M Bethea.

9 recordsLinked to original sources
PubMed1978

Evaluation of a fluorescent dust tracer technique in cotton ginning.

A technique employing a fluorescent tracer for following the break-up and dispersion of cotton trash has been developed. Senescent cotton leaves were treated with a fluorescent dye, pulverized to match the same particle size distribution as naturally occurring leaf in raw seed cotton and uniformly incorporated into the seed cotton mass prior to processing in a saw-type micro-gin. A control lot was similarly processed, excluding any dye. Airborne samples collected from the major fugitive dust emission points by standard techniques, macro trash samples collected from four locations, and the final condensed lint product clearly show that the use of such tracers is not only feasible but highly useful in determining the locations where respirable dust is emitted. From the fraction of labelled tracer material found at any site, the relative amounts of both total and respirable dust emissions of that plant component can be estimated from the known masses of dyed material added to a given mass of seed cotton. Estimates of the relative severity of fugitive dust emissions from various processing steps in a cotton gin are presented based on vertical elutriator, high volume and multistage cascade impactor sampler data.

Coloring Agents↗
PubMed1977

Occupational dust exposures in West Texas cotton gins.

Total and elutriated dust concentrations were measured by four methods for typical ginning situations. Total and elutriated levels were 0.73 and 0.47 and 0.59 and 0.26 mg/m3 per bale/hr by the gin stands and bale press, respectively. Limited data show the corresponding mass media diameters are 9.2-14.8 and 9.6-18.5 micrometer.

Air Pollutants↗
PubMed1977

Effect of chemical defoliation on leaf and bract content in raw cotton.

Chemical defoliants are applied to about 40% of the U.S. Cotton acreage as a harvest-aid practice prior to machine picking. Raw cottons derived from defoliated and nondefoliated fields were examined for content of bract and leaf trash Chemical defoliation lowered, but did not remove, leaf as a major trash component. The content of bract was unaffected by this harvest-aid practice. The histamine content in green leaf trash was 10X that found in nongreen leaf trash.

Byssinosis↗
PubMed1976

Botanical trash present in cotton before and after saw-type lint cleaning.

The % by weight content of leaf-like, stem, boll, seed, and weed materials sifted (3360 mum greater than particle size greater than or equal to 595 mum) from visible wastes of the Shirley Analyzer was determined for a lint sample taken after ginning but before cleaning and for a second lint sample taken after one stage of saw-type cleaning. The % by weight content for bract and leaf increased with decreasing trash particle size. The content of cotton seed coat fragments decreased with reduction in trash particle size. Approximately 1/4 of the botanical wastes consisted of weed materials, including grass particles. Lint cleaning was ineffective in reducing the % by weight content of leaf-like trash. Some selective removal of stem trash occurred as a function of lint cleaning.

Byssinosis↗
PubMed1976

Variation in trash composition in raw cottons.

Raw cotton from 4 machine picked varieties and 2 machine stripped varieties is examined by stereomicroscope and bright-field microscopy for presence of plant trash(bract, leaf, stem, seed, boll, and weed fragments-size range 841-2000mum) that gives rise to cotton dust during yarn manufacturing operations. Bract was found to be the major trash component in all raw cottons examined. Cotton leaf and non-cotton weed materials were also major trash components in most raw cottons.

Byssinosis↗
PubMed1976

A comparison of cotton dust sampling techniques.

The standard high volume sampler, multistage cascade impactor, and modified vertical elutriators were evaluated for total cotton dust sampling. The effects of changes in performance parameters is reported. Mass median dust diameter found in four textile operations for several cotton grades are reported.

Air Pollutants↗