Preliminary steps

Having switched on the apparatus, it should be allowed to equilibrate for about half an hour, so that the electronic system warms up and the conditions settle. During this period the zero mass reading of the balance is likely to drift. The measuring thermocouple system and furnace thermocouples may require reference junctions. If the instrument uses a cold junction reference, at this point the thermos flask should be filled with fresh ice and the sheathed thermocouples inserted. This allows them to cool to 0°C. 

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The principal idea behind the CSP approach is to use input from Classical Molecular Dynamics simulations, carried out for the process of interest as a first preliminary step, in order to simplify a quantum mechanical calculation, implemented in a subsequent, second step. This takes advantage of the fact that classical dynamics offers a reasonable description of many properties of molecular systems, in particular of average quantities. More specifically, the method uses classical MD simulations in order to determine effective... 

Visual and Manual Tests. Synthetic fibers are generally mixed with other fibers to achieve a balance of properties. Acryhc staple may be blended with wool, cotton, polyester, rayon, and other synthetic fibers. Therefore, as a preliminary step, the yam or fabric must be separated into its constituent fibers. This immediately estabUshes whether the fiber is a continuous filament or staple product. Staple length, brightness, and breaking strength wet and dry are all usehil tests that can be done in a cursory examination. A more critical identification can be made by a set of simple manual procedures based on burning, staining, solubiUty, density deterrnination, and microscopical examination. 

If lighter colors than these are desired it is necessary to decolorize all the melanin in the hair in a preliminary step, and then add color back to the desired depth in a second treatment. This is known as a double-process treatment. The decolorization step consists of treating the hair with an alkaline mixture of persulfate salts and peroxide. The persulfate is added to the peroxide as a dry powder immediately before applying to the hair. Although the persulfate salts alone do not have any bleaching effect, the persulfate—peroxide mixture can remove all the melanin in the hair. Dark brown or darker hair can be lightened to a light blonde shade in about an hour. 

If the stock is to receive a second impregnation, it must be rebaked. In the past, stock containing raw impregnating pitch could be graphitized directly. However, the air polluting effect caused by this practice has made rebaking a necessary preliminary step to graphitization in order to achieve effective environmental control. 

Preliminary steps for the initial startup and startup after the overhaul are similar, except for the reservoir and oil requirements on the machine after an overhaul. For an overhauled machine, the oil is drained and tested for condition. If there is no water or metal changes, the oil may be used again. 

First, let us consider batch mixing processes, as exemplified by ordinaiy laboratory practice in solution kinetics. A portion of one solution (say, of the substrate) is added by pipet to a second solution (containing the reagent) in a flask, the flask is shaken to achieve homogeneity, and then samples are withdrawn at known times for analysis, or the solution is subjected to continuous observation as a function of time, for example, by spectrophotometry. For reactions on a time scale (measured by the half-life) of hours or even several minutes, the time consumed in these operations is a negligible portion of the reaction time, but as the half-life of the reaction decreases, it becomes necessary to consider these preliminary steps. Let us distinguish three stages ... 

Figure 21.7.2 demonstrates die preliminary steps for a fault tree analysis (FTA) in addition, die TOP event, bounds, configurations, and unallowed events are specified, and die level of resolution is shown. Once all die limits have been detennined, die fault tree is constructed (Figure 21.7.3). Note tliat every branch of die fault tree ends in a basic fault or cause leading to die TOP event.

Figure 21.7.2 Fault tree analysis (FTA) preliminary steps, ethylene plant.

Isosafrol results from the isomerisation of safrol by heating with alcoholic potash, and this conversion is the preliminary step in the manufacture of heliotropine since isosafrol yields considerably more heliotropine on oxidation than safrol does. Isosafrol has the following constitution —... 

In this connection it should be mentioned that dihalogenomethyl methyl ethers did not furnish the expected / -disuIfone nor the a-halogeno sulfones as preliminary steps in appreciable amounts surprisingly, sulfonyl halides have been isolated as main products of these conversions208 ... 

In the SnIcA and Sn2cA mechanisms (p. 445) there is a preliminary step, the addition of a proton, before the normal SnI or Sn2 process occurs. There are also reactions in which the substrate loses a proton in a preliminary step. In these reactions there is a carbene intermediate. 

In the case of the second boundary-value problem with dv/dn = 0, the boundary condition of second-order approximation is imposed on 7, as a first preliminary step. It is not difficult to verify directly that the difference eigenvalue problem of second-order approximation with the second kind boundary conditions is completely posed by... 

Thermal study is based on experiments which aim at cooling the process fluid. The process fluid temperature can, for instance, easily vary from 20 to 60 °C. Process fluid can be water at room temperature or heated with thermostat, whereas UF is water at 15 °C. Experiments with water are necessary since they allow the study of thermal performances of the reactor regardless of any other phenomenon (reaction, mass transfer, etc.). As a consequence, thermal study is an important preliminary step before performing chemical reactions. For each experiment, the operating protocol is as follows ... 

After this preliminary step, which gives an outline of the heat transfer abihties of the investigated technology, it is possible to consider a chemical reaction and to carry out some energy balances. 

In general, solubilization of appropriate substances in a solution of reversed micelles forming a solid, liquid, or gel core within the reversed micelle is the preliminary step to realize systems easily handled and interesting both from the theoretical and the practical points of view. 

Since no experimental work is available to confront the theoretical model designed to describe C3H2 excited states correctly, test calculations had to be done in a preliminary step. For that purpose, we have chosen ethylene, for which extensive calculations of the vertical spectrum as well as experimental measures are available. It is well known indeed that a correct quantitative and even qualitative description of small rr-electronsystems, is still a challenge for theoretical chemistry. The difficulties are found at each step of the computational approach ... 

In most known examples of catalyzed aromatic nucleophilic substitution (Sr I), the preliminary step aims at producing an aromatic electrophilic radical. Such electrophilicity is obtained, in general " , by substitution on the phenyl ring with a strongly electron-withdrawing substituent (E) which also activates the leaving of the other group (X) and the creation of a transient a radical. 

The position of CFA, as well as that of its related methods, is that of a preliminary step to statistical inference. In this respect, it has been regarded as an... 

The method of PCA can be used in QSAR as a preliminary step to Hansch analysis in order to determine the relevant parameters that must be entered into the equation. Principal components are by definition uncorrelated and, hence, do not pose the problem of multicollinearity. Instead of defining a Hansch model in terms of the original physicochemical parameters, it is often more appropriate to use principal components regression (PCR) which has been discussed in Section 35.6. An alternative approach is by means of partial least squares (PLS) regression, which will be more amply covered below (Section 37.4). 

In our approach to membrane breakdown we have only taken preliminary steps. Among the phenomena still to be understood is the combined effect of electrical and mechanical stress. From the undulational point of view it is not clear how mechanical tension, which suppresses the undulations, can enhance the approach to membrane instability. Notice that pore formation models, where the release of mechanical and electrical energy is considered a driving force for the transition, provide a natural explanation for these effects [70]. The linear approach requires some modification to describe such phenomena. One suggestion is that membrane moduli should depend on both electrical and mechanical stress, which would cause an additional mode softening [111]. We hope that combining this effect with nonlocality will be illuminating. 

Single-stage flash distillation processes are used to make a coarse separation of the light components in a feed often as a preliminary step before a multicomponent distillation column, as in the distillation of crude oil. 

Then the reduction of stored NOx with hydrogen is addressed. The bulk of data points out that the reduction of stored nitrates occurs under near isothermal conditions through a Pt-catalysed surface reaction that does not involve the thermal desorption of the stored nitrates as a preliminary step. A specific role of a Pt—Ba interaction was suggested, which plays a role in the NOx storage phase as well. 

The data clearly indicated that the reduction of NO ad-species is initiated at temperatures well below that of thermal decomposition besides, the temperature onset for the reaction is not affected by the adsorption temperature. This proves that the reduction of stored NO, does not involve as a preliminary step the thermal release of NO in the gas phase, but occurs through a Pt-catalysed chemical route, already active at low temperatures. 

Tiered approach a conservative assessment of, particularly, the exposure can be used in the preliminary steps... 

As a preliminary step towards smaller size, we have tested the equation against the existing data of Barry (1968), James et al (1972) and Thomas and Hinchliffe (1972). One of the authors, EOK, is fortunate to have access to the original Thomas-Hinchliffe data books other data points were read off graphs appearing in the cited... 

In contrast to direct mass spectrometry used in the El mode, ESI often requires specific pretreatments of the samples to purify the components of interest, to increase their yield of ionisation and consequently to improve selectivity and sensitivity. It is thus not a preliminary step of analysis but a method that forms part of an analytical strategy that allows the presence of well preserved high molecular long chain compounds to be shown before their fine characterisation by ESI techniques (Regert et al., 2003a Mirabaud, 2007 Mirabaud et al., 2007). 

Graphite-furnace atomic absorption spectrometry, although element-selective and highly sensitive, is currently unable to directly determine manganese at the lower end of their reported concentration ranges in open ocean waters. Techniques that have been successfully employed in recent environmental investigations have thus used a preliminary step to concentrate the analyte and separate it from the salt matrix prior to determination by atomic absorption spectrometry. 

In conclusion, we are at a very preliminary step on what is probably a long but promising path. The modulation of estrogen action seems a powerful mechanism in the control of CVD risk. Additional advances in the knowledge... 

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