Search

An improved colorimetric method for the determination of boron was developed by investigating the effects of temperature, time, reagent concentration and composition of the reaction mixture on colour development with azomethine-H. Among 15 ions studied, only fluoride, aluminum, ferric and cupric ions interfered with colour development at below 10,000 ppm in sample aliquot. Tolerable concentrations for these ions were 5,000 ppm fluoride, 3,000 ppm aluminum, 2,500 ppm cupric and 200 ppm ferric ion. The method accounted for known additions of boron to nomal hydrochloric acid extract of plant material, to hot water extract of soil and to effluent. Boron determinations in these samples and sewage sludge extract were in close agreement with results obtained by the carmine method. The proposed azomethine-H method was found advantageous since use of concentrated sulphuric acid is avoided and smaller variations in results and superior precision are obtained.

1. 1. In surgically delivered rat infants the administration of puromycin at 3 or 6 hours after delivery leads to potentiation of the postnatal synthesis of tyrosine aminotransferase but puromycin given at delivery effectively prevents production of enzyme activity. 2. 2. Zone sedimentation analysis shows the enzyme activity ‘ induced ’ by puromycin to be of normal size. 3. 3. Hormonal ‘ cocktails ’ containing insulin, hydrocortisone, and adrenaline produce 3 forms of tyrosine aminotransferase in 2-day postnatal rats, adrenaline produces only I form, and puromycin is an apparent inducer in some litters of animals. All these treatments produce tyrosine aminotransferase of the same sedimentation behaviour. 4. 4. Form C of the enzyme is produced by 5 hours after birth of the rat, and when compared with the multiple forms of the enzyme produced by the triple hormonal cocktail, has the same sedimentation characteristics. 5. 5. In a certain proportion of 2-day postnatal rat litters enzyme activity can be increased by adrenaline or puromycin and both agents either are consistently effective or are both ineffective. 6. 6. In ‘ inducible ’ litters, RNase digestion of either liver extracts or the polysomemicrosome fraction increases the enzyme activity in vitro but has no effect in ‘ pre-induced ’ or ‘ non-inducible ’ preparations. 7. 7. The data are interpreted as indicating the operation of a control mechanism working at an enzyme release step in the tyrosine aminotransferase system and taken together with other work it is suggested that this mechanism operates on form C of tyrosine aminotransferase and is mediated at the intracellular level by cyclic AMP.

Smelting and electroplating of metals, motor oils, motor vehicle tires, and fungicide sprays are sources of cadmium in the environment. The factors affecting plant uptake and phytotoxicity of cadmium added to soils were investigated. For a set of 30 surface soils, the addition of 50 mg Cd (from CdCl/sub 2/) to 500 g of soil reduced yield and sharply increased Cd levels in analyzed portions of radish and lettuce plants when compared to those plants grown on control soil. For the treated soil, plant Cd was significantly related to Cd in the soil. From among 18 potential independent variables, stepwise linear regressions to predict Cd found in plant parts harvested from treated soils included a measure of the relative ability of soils to absorb Cd, acetate-soluble Cd in the soil, soil reaction, and organic matter as significantly contributing independent variables. Plant Cd levels were significantly correlated with amounts of nickel, iron, zinc, and copper in the same plant portion. 22 references.

The extent of cadmium contamination of soils in the Lower Fraser Valley (SW, BC, Canada) was evaluated. Nitric acid-soluble cadmium in the surface samples among 33 agricultural soils averaged 0.88 ppM. However, nitric acid-soluble cadmium reached as high as 95 ppM in a surface sample taken near a battery smelter, but this level decreased considerably with distance and depth. The effect of soil application of carbonate, nitrate, chloride, sulfate, and phosphate salts of calcium on cadmium uptake by oats was determined in a growth chamber study involving soils taken near a battery smelter and from farmland. Oats grown on the contaminated soils contained very high amounts of cadmium in the roots, with smaller amounts in the above-ground portions. Soil treatments affected the cadmium content of roots significantly but did not affect the cadmium content of tops.

The thermal conductivity of polycrystalline ytterbium between 90K and 300K was found to increase with temperature. The additional contribution to the thermal conductivity is likely to be due to the bipolar term.