Criticality Concerns

Many models have been proposed for adsorption and ion exchange equilibria. The most important factor in selecting a model from an engineering standpoint is to have an accurate mathematical description over the entire range of process conditions. It is usually fairly easy to obtain correcl capacities at selected points, but isotherm shape over the entire range is often a critical concern for a regenerable process. 

Low-temperature solid-state synthesis is preferred in most cases, where appropriate, for obvious reasons such as energy and cost economy and process safety or for critical concerns regarding the accessibility of compounds that are stable only at low temperatures or non-equilibrium phases, i.e., compounds thermodynamically unstable with respect to the obtained phase (e.g., a ternary instead of binary phase). The use of low-temperature eutectics as solvents for the reactants, hydrothermal growth... 

Action is local Action may be systemic, with side-effects a critical concern... 

A special thanks to Dr. C.W. Schimelpfenig, for encouragement over many years when there was none, and whose comments grace these pages Dr. D.L. Carson, whose comments also appear, for his useful criticism concerning the... 

In 1969, with recognition of environmental problems emerging, the resources of the University were put to work for the benefit of the state of California. Essential characteristics of what was needed to resolve environmental problems became apparent from work addressing California s critical concern air quality. These contrasted with basic research themes. 

Since all triacyglycerols (fats) are hydrophobic, they may be extracted from food samples using hydro-phobic solvents such as various ethers. Also, since fat content in processed foods is of critical concern to consumers, this technique has considerable real-world significance. Rubber gloves should be worn, and it is very important that there be no open flames in the laboratory. 

Toxicity of DDSNs is a critical concern for their applications in biological samples. The toxicity of DDSNs depends on size, surface modification, and dye molecule... 

Gasified coal is expected to be the major source of fuel gas for MCFCs, but because coal contains many contaminants in a wide range of concentrations, fuel derived from this source also contains a considerable number of contaminants. A critical concern with these contaminants is the concentration levels that can be tolerated by MCFCs without suffering significant degradation in... 

Although a number of epidemiological studies have reported an increased risk of lung cancer among occupationally exposed beryllium workers, deficiencies in the studies limit any unequivocal conclusion. Specific criticisms concern the lack of consideration of latent effects, of smoking history, and of exposure to other potential carcinogens and the underestimation of expected lung cancer deaths in comparison populations. "... 

In this chapter, three chemometric methods of increasing importance to SEC are examined nonlinear regression, graphics and error propagation analysis. These three methods are briefly described with emphasis on SEC applications and on critical concerns in their correct implementation. In addition to the specific references cited, further information on these methods and others may be found in a recent book vdiich examines chemometrics in both SEC and HPIiC together (J ) as well as in periodic reviews (2) ... 

Low-molecular-weight vapors can cause vapor locking a critical concern at high altitudes in aviation turbine fuels... 

In analogy to the case of the two-dimensional pseudoasymmetric center (see Section 1.1.2.2.) pseudoasymmetric stereogenic units are encountered when enantiomorphic ligands (F/F) are located in positions of the core (with residual ligands), that are reflection equivalent but not rotationally equivalent, i.e., in enantiotopic positions. Again, lowercase letter descriptors (r/s, pjm) are used in order to express invariance to reflection. The previous criticism concerning the term pseudoasymmetric (see Section 1.1.2.2.) also applies here and will be elaborated in Section 1.1.3.5. 

Using the criteria listed in the introduction, we now provide a brief summary of the performance of these materials. With reference to criterion number 5, physical properties, we restrict out discussion here to the effects of radiation damage on the crystalline structure. For materials destined for geological disposal, the long-term performance in natural systems over long periods of time (e.g., 103 to 106 years) is of critical concern. Therefore, we believe that it is necessary to consider one more criterion (6) natural samples exist and allow for an assessment of the... 

The ecotoxicology of pharmaceuticals is of critical concern to the issue of PIE. The all important question is not whether pharmaceuticals are present in the environment-there is ample evidence that they are-but, at the concentrations at which they are found, whether they do any harm The almost universally used paradigm for attempting to answer this question is the comparison of the Predicted Environmental Concentration (PEC) with the Predicted No Effect Concentration (PNEC)-the so called PEC/PNEC ratio. 

A critical concern of all approaches is measurement specificity. The atmosphere is a complex mixture of gases and aerosols with a multitude of opportunities for interferences and artifacts. One means of approaching definite specificity is through spectroscopic techniques. Such techniques are most readily applied to the stratosphere, where the ambient pressure is low enough to avoid serious pressure broadening of spectroscopic features. Stratospheric applications are briefly surveyed in the Measurement Platforms section. 

Gray, B. F. and Morley-Buchanan, T., 1985, Some criticism concerning the Brusselator model of an oscillating chemical reaction. J. Chem. Soc. Faraday Trans. 2 81, 77. 

A critical concern in the use of organofunctional silanes is the effects that the organofunctional groups and the silane ester groups have on the hydrolysis reactions occurring at silicon. 

In environmental studies, the analyst is concerned with stable compounds or stable products in metabolic studies, the question of reactive (therefore unstable) products and intermediates is of critical concern. Thus the reaction must be stopped, and the sample must be processed using techniques that minimize degradation. This is facilitated by the fact that the substrate is known, and the range of possible products can be determined by a variety of methods. 

The following table provides guidance in the selection of optics materials.1 Often, the solubility in (pure) water of a particular material is of critical concern. 

FD-483 trends and warning letters published on the FDA home page or through various industry publications provide tremendous insight into FDA s current areas of critical concern. They should be analyzed within the context of individual company circumstances. 

Of critical concern is the possibility that developmental exposure may result in an acceleration of age-related decline in function. Animal studies have demonstrated that developmental exposure to neurotoxicants such as methylmercury, methylazoxymethanol, and ethanol may cause few or no neurotoxic effects in young animals, but marked effects in ageing animals. Investigations of effects in ageing animals are not included in regulatory guidelines. 

This reaction is the dominant dehalogenation pathway in reduction of halogenated methanes [84] and haloacetic acids [85]. In Fig. 4, this reaction is illustrated for perchloroethene (PCE), where complete dechlorination by this pathway requires multiple hydrogenolysis steps. The relative rates of these steps are a critical concern because they determine whether... 

Overheating of the adhesive is always a critical concern with induction curing. This is especially true when the adhesive cures with a high exotherm, such as epoxy-dicyandiamide systems. Several proprietary epoxy curing agents have been developed that provide lower exotherm yet faster cure rate than typical dicyandiamide reactions.27,28 Tertiary amines and modified polyamines29 are often used to accelerate the cure of dicyandiamide-epoxy... 

---