Precautions 606 INDEX

Workers in the metals treatment industry are exposed to fumes, dusts, and mists containing metals and metal compounds, as well as to various chemicals from sources such as grinding wheels and lubricants. Exposure can be by inhalation, ingestion, or skin contact. Historically, metal toxicology was concerned with overt effects such as abdominal coHc from lead toxicity. Because of the occupational health and safety standards of the 1990s such effects are rare. Subtie, chronic, or long-term effects of metals treatment exposure are under study. An index to safety precautions for various metal treatment processes is available (6). As additional information is gained, standards are adjusted. 

The tendency towards explosive decomposition noted for dihalo-2,4-hexadiyne derivatives appears to be associated more with the co-existence of halo- and acetylene functions in the same molecule, than with its being a polyacetylene. Haloacetylenes should be used with exceptional precautions [1], Explosions may occur during distillation of bromoacetylenes when bath temperatures are too high, or if air is admitted to a hot vacuum-distillation residue [2], Precautions necessary in isolating and handling such compounds on the small (1 g) scale are detailed [3], Individually indexed compounds are ... 

Many compounds containing either single or multiple bonds between N and S show a considerable degree of instability. Information is given on hazards of, and precautions in handling derivatives of cyclic N-S compounds [1], Individually indexed compounds are ... 

Care is required with these compounds since many explode on heating [1], A number of triazene derivatives bearing hydrogen, or cyano, hydroxy or nitroso groups on the terminal nitrogen of the chain are unstable, mainly to heat [2], Purification of triazenes by vacuum sublimation carries the risk of explosion [3], Further examples of unstable triazenes and precautions are given [4,5], Individually indexed compounds are ... 

The second approach using gradient mode to assess log P values first proposed by Valko et al. is the use of the chromatographic hydro phobicity index (CHI) obtained from a single fast gradient run (<15 min) [103]. Since CHI is considered as a relevant parameter for QSAR studies, it was demonstrated using LSER that differences occur between CHI parameters and true log P because C HI (and log k) are sensitive to H-bond acidity ability whereas log P is not [104]. Thus, CHIs have to be used with precaution. 

The light-scattering apparatus and procedure have been formerly described (15). The only modification and precaution with polybutadienes were to use the appropriate refractive index differential for each polymer as this was observed to decrease with vinyl content values used were 0.118, 0.112, and 0.106 dl/gram for 2, 10, and 20% vinyl polybutadienes in cyclohexane at 25 °C and 546 m//,. 

Analysis of ternary mixtures of certain drugs including salicylamide were studied by plotting the refractive index isotherms of the fused mass and the isotherms of the primary crystals on triangular concentration diagrams. The influence of each factor upon the quantitative determination could be found. In each case there was an area unsuitable for measurement where the isotherms were practically parallel when this was not the case, quantitative determination was possible. Precaution should be taken to prevent loss of highly volatile components (7l). 

Precautions The tricyclic antidepressants should be used with caution in manic-depressive patients, since they may unmask manic behavior. The tricyclic antidepressants have a narrow therapeutic index for example, 5 to 6 times the maximal daily dose of imipramine can be lethal. Depressed patients who are suicidal should be given only limited quantities of these drugs and should be monitored closely. Drug interactions with the tricyclic antidepressants are shown in Figure 12.5. 

Unfortunately, enzyme activity measurements are considerably more complex than simply quantifying enzyme proteins or the production ofmetaboHtes. Achieving efficient extraction of proteins of interest can be challenging and the cellular environment or environments in which the enzyme operates may be difficult to simulate in vitro. In this section we consider general approaches to activity assays (e.g., strategies and types of assays), practical considerations (e.g., precautions and controls), kinetic measurements, and interpretation (e.g., deciding whether an enzyme activity can serve as an index of a metabolic rate). 

Several techniques have been developed to measure the electro-optic susceptibility of single crystals or thin films. All are based on the measurement of variation of the refractive index of a material induced by the applied external field. We will shortly describe the modulation ellipsometry technique [18,19], which is relatively simple in use and can be applied to thin films, provided that some precautions are undertaken [20]. 

In the 1980s, many programs were developed to automatically perform this indexing process (for example [LOU 82, WER 85]). The calculations are usually quick, but leave the user in the dark , since he takes no part in the process. The success in lattice identification is essentially determined by the quality of the measurements. Most of the time, a measurement error which is smaller than a hundredth of a degree is required. This a severe condition and it calls for strong precautions when making the measurements. 

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