Spaced dosages

Widely spaced dosages are better than narrowly spaced dosages. 

The NOEL depends greatly on the selection of dosage levels unless the selected dosage is just below the threshold for detectable effects, the reported NOEL is an underestimate thus, tightly spaced dosage levels favor the determination of a higher NOEL. 

Abdallah A, Saif M, el-Mawla NG, Abdel-Fattah F, Aly IM. Spaced-dosage treatment of bUhaiziasis with niridazole. J Egypt Med Assoc 1968 51(9) 823-30. 

Figure 2 An experimental design showing unequally spaced dosages and theoretical results used for extrapolation to estimate the no-observed-adverse-effect level (NOAEL) or the no-ob-served-effect level (NOEL). In curve A, some slight degree of toxicity was observed at the lowest dose administered, permitting only the estimation of an NOAEL. In curve B, no toxicity was observed at the lowest dose, and slight toxicity at the intermediate dose, permitting the estimation of a NOEL and a NOAEL.

The primary use for methyl bromide is in the extermination of insect and rodent pests. Methyl bromide is used in space and stmctural fumigation except in California. The material is suitable for the fumigation of food commodities such as dried fmits, grain, flour, and nuts, and the faciHties in which these foods are processed or stored, as weU as for tobacco and many kinds of nursery stock. The usual dosage is 2—4 kg/28 m for 12—24 h. In soil fumigation methyl bromide controls weed seeds, nematodes, wireworms, and soil fungi. The usual dosage is 0.5—1 kg/9 m for 24 h at 16°C and above (82). 

Application of this system in the continuous transfer-hydrogenation reaction of acetophenone gave a stable conversion of about 87%, an ee of 94%, and a space-time yield of 255 g L"1 d"1. A continuous dosage of isopropoxide was necessary in order to compensate for deactivation caused by traces of water in the feed stream. Under these circumstances a TTON of 2360 was reached. Comparison of this system with an enzymatic process showed that both approaches offer different advantages and are therefore complementary. 

Figure 25. Nominally 0.5 um (a) and 1.0 ixm (b) PSTTF lines spaced 1.0 ixm apart in 2.4-ixm thick PMMA (Elvacite 2041). The PSTTF caps are 0.3-iim thick delineated with a 10-uClcm e-beam dosage.

Using 2-5% of the original dosage of AEA is sufficient to increase the air content to the original level and provide a suitable spacing factor [136],... 

It is possible to correct an unsatisfactory AVS by adding more AEA after 45 min, but to lower significantly the value of the spacing factor, the quantity of the admixture that is added must be significant (>30-50% of the normal dosage) to cause a marked increase in air content. 

Neutralized vinsol resin, sulfonated hydrocarbon, and fatty-acid (detergent)-based AEAs give satisfactory AVSs, but at low dosages, only synthetic detergent-based materials can produce an adequate and stable spacing factor. 

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