Separation specifications

Extraction (discussed in Chapter 5) uses the selective adsorption of a component in a liquid to separate specific molecules from a stream. In application extraction may be coupled with its cousins, extractive distillation and azeotropic distillation, to improve extraction efficiency. Typical refinery extraction applications involve aromatics recovery (UDEX) and lubricants processing (furfural, NMP). Extractive distillation and azeotropic distillation are rarely employed in a refinery. The only... 

Solution A liquid mixture of dissolved substances, displaying no phase separation. Specific gravity Weight of a particle, substance or chemical solution in relation to an equal volume of water. 

Maximum benefit from Gas Chromatography and Mass Spectrometry will be obtained if the user is aware of the information contained in the book. That is, Part I should be read to gain a practical understanding of GC/MS technology. In Part II, the reader will discover the nature of the material contained in each chapter. GC conditions for separating specific compounds are found under the appropriate chapter headings. The compounds for each GC separation are listed in order of elution, but more important, conditions that are likely to separate similar compound types are shown. Part II also contains information on derivatization, as well as on mass spectral interpretation for derivatized and underivatized compounds. Part III, combined with information from a library search, provides a list of ion masses and neutral losses for interpreting unknown compounds. The appendices in Part IV contain a wealth of information of value to the practice of GC and MS. 

The art of good documentation is the art of leaving things out but in a consistent and useful way so that your documents are well structured, concise, and readable. In a sense, our ideal documentation would look like a cross between Knuth s Web of literate programming and a clear structure that separates specifications and external views of things from their internals. 

The reason for using these join mles for actions is that each action specification could have been written without knowledge of the other specification or of its attributes. When I write my preconditions I do not know what other preconditions you may want to impose on that action we both should be confident that, when our separate specifications are joined together, each can rely on its restrictions still being in force. The same principle applied to postconditions. 

Hence, these two different styles of writing specs can be used to accomplish these two different goals of composing separate specifications. More details on dealing with exception conditions in specifications appear in Section 8.4, Action Exceptions and Composing Specs. 

When you join type specifications, you are combining the descriptions themselves and not directly the types (sets of objects) they specify. In the usual case, two type specifications are joined when a package, P1, imports two other packages—P2 and P3—each of which provides separate specifications (Ts1 and Ts2) for the same type, T. Within package P1, the resulting specification of type T is the specification that results from a join ... 

Pattern 14.30, Specify components (p.615) motivates the extra effort involved in separating specification of expected behavior from its implementation. Pattern 14.31, Bridge requirements and specifications (p.617) outlines a pragmatic view of requirements, as stated and understood by a user, and the more precise specifications that a developer might use to understand what must be built. Pattern 14.32, Use-case led system specification (p.619) explains why a use-case driven approach to requirements capture is prudent, but should always be interleaved with tools of more precise specifications. 

GC is particularly useful in soil analysis because of both the wide variety of columns available for separating specific mixtures and because of the variety of very sensitive detectors available. There are specific columns for separation of gases commonly found in the soil atmosphere and specific columns for the analysis of herbicides, insecticides, and pollutants. 

Intermetallic chemistry is closely connected to the subject matter of inorganic chemistry several groups of substances, for instance, may be conveniently presented in the systematic descriptive sections of both subjects. There are, however, several distinctive features which justify separate specific treatment. We just underline here a few characteristics of intermetallic chemistry which, we believe, are peculiar to the domain of descriptive chemistry and to which special chapters are dedicated in this book. 

Porosity. It is implicit in the permeability requirement typically lithium-ion battery separators have a porosity of 40%. Control of porosity is very important for battery separators. Specification of percent porosity is commonly an integral part of separator acceptance criteria. 

There is one separate tRNA for each amino acid and one separate specific synthetase. The enzyme must bind not only the correct amino acid but also the correct tRNA, so that each synthetase has specific recognition sites for both. Transfer RNAs contain a three-base sequence that is an anticodon, which binds to its complementary codon on messenger RNA. The importance of the synthetase in relation to fidelity of translating the information in messenger RNA is indicated by the fact that, once an amino acid is bound to tRNA, its identity as an amino acid is dictated by the anticodon site on the transfer RNA and not by the amino acid itself. (The enzyme can be considered as a dictionary, since it provides a cross-reference between the nucleic acid and amino acid languages.)... 

Supercritical fluids were soon found to be highly efficient extraction media, chiefly because of their high solvating power, their low viscosities (intermediate between a gas and a liquid), and their low surface tensions that enable their penetration deep into the extraction matrix. Supercritical fluid extraction (SEE) used in isolation is generally not selective enough to separate specific solutes from the matrix without further cleanup or resolution from coextracted species prior to qualitative and quantitative analysis. Consequently, for analytical applications, SFE is usually used in combination with chromatographic techniques to improve the overall selectivity in the isolation of specific solutes. The combined use of SFE with chromatographic techniques is quite recent. 

Separation by Selective Oxidation or Reduction. Since a change of oxidation is accompanied by a substantial change in properties, selective oxidation or reduction provides a remarkably clean and efficient way of separating specific lanthanides. 

Complementary structures of biological materials, especially those of proteins, often result in specific recognitions and various types of biological affinity. These include many pairs of substances, such as enzyme-inhibitor, enzyme-substrate (analog), enzyme-coenzyme, hormone-receptor, and antigen-antibody, as summarized in Table 11.2. Thus, bioaffinity represents a useful approach to separating specific biological materials. 

When all of the coefficients are known, this can be solved for the concentrations of component i in every stage. A straightforward method for solving a tridiagonal matrix is known as the Thomas algorithm to which references are made in Sec. 13.10, Basis for Computer Evaluation of Multicomponent Separations Specifications. ... 

Chapter 8 constitutes a separate specification of abrasiveness test results for a number of materials, to give the reader an idea of the range of problems that can be tackled in a laboratory using the methods described in the book. These results, not necessarily to be interpreted as hardness, could not be brought within the scope of Chapter 4 on methods. 

Immunoaffinity chromatography makes use of immobilized antigen molecules to bind and separate specific antibody from a complex mixture. After the preparation of an... 

An investigation was made to determine the feasibility of the combination process of volatility amplification of nonvolatile mixtures by the addition of supercritical fluids followed by contacting the vapor with molecular sieves to separate specific materials from the mixtures. Two potential advantages of this novel combination become possible. 

The exclusive consideration of common factors seems to be promising, especially for such environmental analytical problems, as is shown by the variance splitting of the investigated data material (Tab. 7-2). Errors in the analytical process and feature-specific variances can be separated from the common reduced solution by means of estimation of the communalities. This shows the advantage of the application of FA, rather than principal components analysis, for such data structures. Because the total variance of the data sets has been investigated by principal components analysis, it is difficult to separate specific factors from common factors. Interpretation with regard to environmental analytical problems is, therefore at the very least rendered more difficult, if not even falsified for those analytical results which are relatively strongly affected by errors. 

If the mouse does not show a heightened response to the startle stimulus in the testing trials, it may have cognitive deficits. Memory should be examined in separate, specific tests to ensure accurate data interpretation. 

The ability to separate specific solution components from the liquid phase with a supercritical or near-critical solvent component has been demonstrated for a few selected systemsQ). Generally, the solvents are single component inorganic gases or light hydrocarbons. 

Specification of the separation. A separation is specified by defining column feed flow rate and composition, overhead solute concentration (alternatively, solute recovery), and the concentration of solute (if any) in the lean solvent. If the purpose of absorption is to generate a specific solution, as in acid manufacture, the solution concentration completes the separation specification. For all other purposes, one specifying variable (e.g., rich solvent concentration or solvent flow rate) remains to be specified and is usually set by optimization as outlined below. 

Mujtaba and Macchietto (1988) and Mujtaba (1989) used two typical binary mixtures and a variety of separation specifications to demonstrate how optimal recycle policies can be obtained and to assess the validity of the degree of difficulty measure. The mixtures were 1) Benzene-Toluene 2) Butane-Pentane. For simplicity ideal equilibrium and Antoine s vapour pressure equations were used. The light component was always the first one. 

Usually separation specifications in multicomponent mixtures are imposed on a particular (key) component of the cut, e.g. on component 1 in main-cut 1, on component 2 in main-cut 2 and likewise. Of course, it is possible to set intuitively some of the heavier component compositions to zero during lighter cuts and some of the lighter component compositions to zero during heavier cuts. But it is really difficult to specify independently the compositions of the preceding and few successive component compositions in a particular cut. 

---