Problems created

The problem with the fiowsheet shown in Fig. 10.5 is that the ferric chloride catalyst is carried from the reactor with the product. This is separated by washing. If a reactor design can be found that prevents the ferric chloride leaving the reactor, the effluent problems created by the washing and neutralization are avoided. Because the ferric chloride is nonvolatile, one way to do this would be to allow the heat of reaction to raise the reaction mixture to the boiling point and remove the product as a vapor, leaving the ferric chloride in the reactor. Unfortunately, if the reaction mixture is allowed to boil, there are two problems ... 

The prevacuum technique, as its name implies, eliminates air by creating a vacuum. This procedure faciUtates steam penetration and permits more rapid steam penetration. Consequendy this results in shorter cycle times. Prevacuum cycles employ either a vacuum pump/steam (or air) ejector combination to reduce air residuals in the chamber or rely on the pulse-vacuum technique of alternating steam injection and evacuation until the air residuals have been removed. Pulse-vacuum techniques are generally more economical vacuum pumps or vacuum-pump—condenser combinations may be employed. The vacuum pumps used in these systems are water-seal or water-ring types, because of the problems created by mixing oil and steam. Prevacuum cycles are used for fabric loads and wrapped or unwrapped instmments (see Vacuum technology). 

The optimum predictive maintenance program developed in earlier chapters is predicated on vibration analysis as the principle technique for the program. It is also the most sensitive to problems created by the use of the wrong transducer or mounting technique. 

A) The use of a calibration graph. This overcomes any problems created due to non-linear absorbance/concentration features and means that any unknown concentration run under the same conditions as the series of standards can be determined directly from the graph. The procedure requires that all standards and samples are measured in the same fixed-path-length cell, although the dimensions of the cell and the molar absorption coefficient for the chosen absorption band are not needed as these are constant throughout all the measurements. 

Within these tortuous systems there exists considerable opportunity for process contamination, corrosion, and equipment malfunction to occur, with cause-and-effect problems creating further impact downstream and placing additional demands on monitoring and control efforts. 

The moiutoring framework should be designed to miiumize the iirfluence of such factors or to control for them in the analysis process. While no moiutoring strategy can account for all possible complexities, the authors believe this monitoring framework has identified the best currently available solutions to address problems created by these confounding factors. 

The problem with the flowsheet shown in Figure 28.5 is that the ferric chloride catalyst is carried from the reactor with the product. This is separated by washing. If a design of reactor can be found that prevents the ferric chloride leaving the reactor, the effluent problems created by the... 

During the past years, several approaches have been suggested to the Commission of the European Communities, in order to reduce the problem created by the large number of reaction to fire tests. 

Solves the waste disposal problems created by land bans... 

The above represent the past and present of the most common enzyme-mediated methods of antigen detection. There are alternate procedures available, involving such methods as antibiotin antibody steps that combine the avidin-biotin systems with a further antibiotin/antienzyme sandwich for still greater sensitivity. Also, there are methods that follow a PAP procedure with a biotinylated antibody to the PAP immunoglobulin followed by ABC detection (15). The obvious problem created with this approach is the tremendous... 

The problems created by sulfur have changed as the industry progressed just over twenty-five years ago the main problems were to make straight-run gasoline and kerosene without offensive odor and of suitably low sulfur content. Since then the complexities... 

In summary, spatial separation of reaction mixtures from the lamp jacket is one of the most efficient means of preventing filming (see also earlier comments on laser photolysis). In addition, as shown in Figure 7, the same principles of design may be used for solving problems created by inner filters. 

Let us examine some of the problems created by these factors ... 

The third problem that needs to be controlled is that of spectral cross-over and the possibility of incorrect instrument compensation. As an example of a case in which controls for nonspecific staining, autofluorescence, and compensation are all critical, let us look at the staining of B lymphocytes for the CD5 marker present with only low density on their surface. As well as the problems created by nonspecific staining and by autofluorescence, the problem of spectral cross-over between fluorescein and phycoerythrin can particularly confuse the interpretation of results from this kind of experiment. Look at Figure 6.5. What we are interested in is the number of B lymphocytes that possess the CD5 surface antigen. These cells will appear in quadrant 2 of a contour plot of fluorescein fluorescence... 

As for hybrid modeling, the problem of the foundations of MM is seen from a somewhat different perspective. A priori there is no limitation for employing that or any other MM scheme as a classical component of a hybrid model. In practice, however, different MM schemes behave differently when tailored to a QM treated part. Indeed, it is not clear how to handle the bond-dipole based electrostatic energy employed in the MM2 and MM3 schemes, if some bond must be broken, as their ends are expected to be treated by different methods. It applies even more to the schemes with charge equilibration. We shall try to describe the problems created by these inconsistencies as related to the current hybrid methods in the next section, with the analysis of the current state of the art, from the point of view of the general theory of electron variables separation. 

---