Relative Efficiency Index Research Articles

Efficiency of Granulated Insecticides Influenced by Solvents Used for Impregnation12

In mosquito larviciding and other aquatic insect pest control programs, quick kill of the larvae of the insects before they can change into pupae and adults is necessary. The use of granulated insecticides in such control measures has great possibilities, provided the formulations are capable of releasing a large portion of the toxicants within 24 hours after treatment. Formulations that release the toxicant slower are not desirable except possibly in certain prelarviciding treatments for mosquito control. The efficiency of 44 petroleum solvents was investigated in a study of the various physical and chemical factors influencing and regulating the rate and magnitude of release of toxicants from granular formulations. The solvents had a wide range of physical and chemical properties. A 2% parathion impregnated formulation was prepared using 30/60 mesh, AA-LVM attapulgite granules. The granules were dropped into water and the rate of parathion release was determined by bioassaying aliquots of the treated water against fourth-instar larvae of Culex quinquefaseiatus Say. The rate and magnitude of release for almost all of the petroleum solvents (aromatics, paraffins, and naphthenes) were found to be affected to a great extent by the flash point, minimum and maximum boiling points, distillation range and evaporation rate of these solvents. It was further noted that there existed an inverse relationship between the rate and extent of release and these physical characteristics of the solvents. With an increase in the values of these properties there was a tendency for slower releases and vice versa. A simple formula has been presented which illustrates this relationship, as follows: REI = FP × IBP (EP-IBP) 105 Where REI is relative efficiency index, FP is flash point, IBP is initial boiling point, and EP is end point. Solvents with higher REI values generally resulted in formulations releasing parathion slower than those prepared with solvents having lower REI values. Solvents with extreme distillation properties are easily separated by this formula. By selecting suitable solvents to impregnate granules with the toxicant solution, it is possible to prepare a wide array of granular formulations which will give either slow, intermediate, or rapid release of the toxicant depending on the particular solvent. The studies reported are aimed at gross separation of petroleum solvents into highly efficient, less efficient and inefficient solvents which might be used for impregnation of granular carriers with parathion.

Studies of the Energy Requirements of Chickens: 4. Evidence for a Linear Relationship Between Dietary Productive Energy Level and the Efficiency of Egg Production

COMPARATIVE studies of the efficiency of utilization of rations for egg production are made difficult by the well known fact that gross efficiency, measured as feed requirement per dozen eggs produced, is markedly affected by rate of production. Because of this relationship relatively small differences in egg production rate, which may be of limited or no significance in themselves, have the effect of masking or magnifying the respective differences between rations in efficiency of feed utilization.Bird and Whitson (1946) were the first to attempt to circumvent this difficulty by comparing the observed rate of feed consumption to that predicted by the Byerly (1941) partition equation on the basis of the observed rate of production, average body weight and weight gains. From the observed and predicted rates of feed consumption, an index of relative efficiency was calculated for each ration under study.Lillie and coworkers (1952), using a similar procedure, …

A study in soil cultivation. The effects of varying soil consolidation on growth and development of rain-grown cotton

1. Experiments were carried out in four seasons at Barberton, South Africa, occupying approximately 2¼ acres of ground. Three soil treatments were used, viz. Normal (N), Compressed (C) and Grubbed (loosened) (G).2. Measures of consolidation of the soil were made with a specially designed apparatus, and large differences established (pp. 516–520).3. Estimations of water content and nitrate content were carried out. No great differences were found (pp. 520–524).4. Fortnightly samples of the plants were taken, from which numerical data were collected designed to estimate morphological development (primary data, pp. 526–529).5. Derived data on net assimilation rate, relative leaf-growth rate and efficiency index were calculated (pp. 529–533).6. Growth in total dry weight was found to conform approximately with an exponential law up to the time of flowering. Up to this stage also net assimilation rate was found to remain constant.7. Growth differences between treatments were related to variation in net assimilation rate only (p. 531).8. The results were analysed statistically. Significant results alone are emphasized.9. In all respects growth and development on the consolidated soil was more rapid than that on the grubbed soil, normal being generally intermediate.10. The results are discussed with reference to the question of nitrogen supply, water supply and aeration of the soil.