Fluorescent Tracer Technique Research Articles

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.

Fluorescent tracer method for protein SH groups. II

An improved fluorescent tracer technique for protein SH groups is described using a fluorescent thiol reagent, N-(7-dimethylamino-4-methylcoumarinyl)-maleimide. The direct measurement with a scanning fluorometer of the fluorophore-labeled proteins separated by SDS polyacrylamide gel electrophoresis achieved a simple, precise, and sensitive determination of the SH group of the order of picomoles per band. In addition, the direct recording of peaks enabled us to analyze more complex protein systems, compared with our previously reported method using an extraction step from gel slices. As an application, we compared the reactivity of the SH groups of proteins in glycerinated muscle fibers under two conditions, in rigor and in contraction.

Cerebral circulation after cardiac arrest. Microangiographic and protein tracer studies.

The effects of ventricular fibrillation and subsequent resuscitation on the microcirculation of the verebral cortex were studied with microangiographic and fluorescent protein tracer techniques. Immediately after revival, a transient period of impaired cerebral perfusion occurred before complete recovery from circulatory arrest was obtained. A circulatory arrest of longer than ten minutes, followed by four to six hours of resuscitation, caused defects of cortical capillary filling in both microangiography and Trypan blue fluorescence. This was considered to represent impairment of cortical perfusion, most likely due to edema. Cardiac arrest up to 12 minutes and subsequent resuscitation per se caused no blood-brain barrier damage. Minimal blood-brain barrier damage occurred in one dog following uncomplicated revival from a 14-minute arrest and in animals with prolonged hypertension post-resuscitation. Up to three consecutive carotid angiographies did not cause blood-brain barrier damage in the postischemic brain.

Fonction de transfert d'un réservoir agité en système continu: II Variation des constantes de temps avec et sans différence de densité initiate

AbstractThe analysis of the dynamic behavior of a continuous stirred tank reactor with a fluorescent tracer has indicated that the short‐circuit of a fraction of the liquid feed constitutes the only non‐ideality in this case. There is no dead space or piston flow in the reactor when the density difference is zero.The variation of the transfer function time constants was also studied as a first approximation, in a reactor with a density difference between the liquid feed and the reactor contents. This had led to the determination of an ideality criterion which includes the main causes of the non‐ideal mixing. The fluorescent tracer technique has permitted the isolation of the effects of physical parameters on the degree of short‐circuit from the effects on other causes of non‐ideal mixing.

A fluorescent tracer technique for determination of the liquid distribution of field crop sprayers

A fluorescent tracer technique is described for the examination of evenness of liquid distribution by moving field crop sprayers and the sensitivity of different types of nozzles to the movement of a spray boom.

FIELD INVESTIGATIONS CONCERNING THE SELECTIVE PHYTOTOXICITY OF DI‐ALLATE TO AVENA SPP. IN WHEAT AND BARLEY

Summary. The following factors influencing the selectivity of di‐allate against Avena spp. in spring wheat and barley have been investigated in seven field experiments: (a) depth and degree to which the herbicide is mixed with the soil, (b) time of application of the herbicide relative to sowing the crop, (c) implement used to incorporate the herbicide with the soil, (d) depth of germination of the Avena spp.Di‐allate and tri‐allate incorporated relatively deeply before drilling the crop controlled Avena spp, much more effectively than when incorporated shallowly by chain‐harrowing after drilling, but the pre‐drilling treatments were also more toxic to the crop.In wheat, di‐allate incorporated shallowly after drilling was slightly more selective than when incorporated more deeply before drilling but in barley there was no evidence to favour either time of application. Pre‐drilling treatments incorporated by a rotary cultivator were a little more selective to both crops than those incorporated by springtine harrows.Tri‐allate was more selective than di‐allate, in wheat, when incorporated before drilling the crop. There was no evidence regarding its selectivity as a post‐drilling treatment.The initial distribution of the herbicide in the soil, after incorporation by: (a) spring‐tine harrowing once, (b) rotary cultivating once or twice, or (c) chain harrowing once, was measured in one experiment by a fluorescent tracer technique. The results showed that ordinary farm implements give a very uneven distribution (both vertical and lateral) of herbicide in the soil.In the field, di‐allate and tri‐allate incorporated with the soil shallowly after drilling proved to be less selective and less active than similar treatments in the glasshouse. It is suggested that the reduced selectivity of these treatments in the field is due to loss of herbicide by vaporization and retention of the herbicide by the soil under dry conditions.The importance of the various factors influencing the selectivity of di‐allate and triallate in the field is discussed in the light of the results of these experiments and those of other research workers (particularly Parker, 1963).Essais de plein champ sur la phytotoxicité sélective du di‐allate envers les Avena spp. dans le blé et l'orge

Application of Fluorescent Tracing Techniques to Hydrologic Studies

This article discusses the use of Rhodamine B as a suitable tracer in hydrologic studies.