First step

The secondary reactions are parallel with respect to ethylene oxide but series with respect to monoethanolamine. Monoethanolamine is more valuable than both the di- and triethanolamine. As a first step in the flowsheet synthesis, make an initial choice of reactor which will maximize the production of monoethanolamine relative to di- and triethanolamine. 

As an example, consider again the manufacture of vinyl chloride. In the first step of this process, ethylene and chlorine are reacted to form dichloroethane ... 

It now appears that many hormones (e.g. glucagon and adrenaline) in both animals and plants exert their effects by, as a first step, decreasing or increasing cyclic AMP within the cell. This may possibly occur by modification of the activity of the enzyme AMP cyclase which generates cyclic AMP from ATP. 

HSCH -CHNHj-COjH. Cysteine is a reduction product of cystine. It is the first step in the breakdown of cystine in the body, one molecule of cystine splitting to give two molecules of cysteine. Cysteine is soluble in water but the solution is unstable, and is reoxidized to cystine. 

Along the same lines, a distillation can be simulated by gas phase chromatography. As in a refinery, distillation in the laboratory is very often the first step to be carried out, because it gives the yields in different cuts gasoline, kerosene, etc., and makes further characterization of the cuts possible. 

If no prior drilling activities have been recently carried out in the area, usually an environmental impact assessment (EIA) will be carried out as a first step. An EIA is usually undertaken to ... 

In the first step, a screening process will be applied to separate the major potential hazards these will be addressed in more detail. QRA techniques are used to evaluate the extent of the risk arising from hazards with the potential to cause major accidents, based on the prediction of the likelihood and magnitude of the event. This assessment will be based on engineering judgement and statistics of previous performance. Where necessary, risk reduction measures will be applied until the level of risk is acceptable. This of course is an emotive subject, since it implies placing a value on human life. 

Appraisal activity should be based upon the information required. The first step is therefore to determine what uncertainties appraisal is trying to reduce, and then what information is required to tie down those uncertainties. For example, if fluid contacts are a major source of uncertainty, drilling wells to penetrate the contacts is an appropriate tool seismic data or well testing may not be. Other examples of appraisal tools are ... 

Forward modelling is the first step for inverting data for the reconstruction of the defect. For this purpose, the specialised code is better adapted because it is faster than the general code. 

The first step will establish certain minimum requirements for those parameters that are defined in part 1 inherent unsharpness, contrast sensitivity, distortion, and homogeneity. The result will be three different equipment classes SC1, SC2, SC3 (see table 1). 

The sensitivity curves are plots of maximum achieved sensitivity as a function of thickness of the object for a given focal spot size and source to detector distance. The best attainable sensitivity in image intensifier systems is a function of tube voltage, current, scattered radiation and the screen gamma. As a first step, stainless steel plates with thicknesses ranging from 5 mm-30 mm in steps of 5 mm were chosen. These plates had a length of 950 mm and width of 280 mm. The plate is positioned very close and at the center to the LI. tube. The extraneous... 

As a first step in the direction outlined here some manufacturers and BAM last year discussed the problems and the possible procedures of such a system of quality assurance. As a result of this meeting round robin tests for the harmonization of the measurements of film system parameters and a possible procedure of surveillance of the quality of film systems were proposed. Closely related to these the BAM offers to perform the classification of film systems. But as during the production of films variations of the properties of the different batches cannot be avoided, the results of measurements of films of a single batch will be restricted to this charge, while only the measurements and mean of several batches of a film type will give representative values of its properties. This fact is taken into account already in section 4 of the standard EN 584-1 which can be interpreted as a kind of continuous surveillance. In accordance with this standard a film system caimot be certified on the base of measurements of a single emulsion only. 

The first step involved massive testing at ANDREX laboratory to determine the optimal detection process. Two imaging methods were discussed, one using a linear detector array, the other using a high resolution image intensifier. 

The figures 9 and 10 show the A-Scans of these two steps. Figure 9 presents the velocity measurement of the longitudinal wave parallel to the surface in the first step and figure 10 presents the A-Scan of the thickness measurement in the second step. 

The Fischer-Tropsch reaction is essentially that of Eq. XVIII-54 and is of great importance partly by itself and also as part of a coupled set of processes whereby steam or oxygen plus coal or coke is transformed into methane, olefins, alcohols, and gasolines. The first step is to produce a mixture of CO and H2 (called water-gas or synthesis gas ) by the high-temperature treatment of coal or coke with steam. The water-gas shift reaction CO + H2O = CO2 + H2 is then used to adjust the CO/H2 ratio for the feed to the Fischer-Tropsch or synthesis reactor. This last process was disclosed in 1913 and was extensively developed around 1925 by Fischer and Tropsch [268]. 

With the density fiinctional theory, the first step in the constmction of a pseudopotential is to consider the solution for an isolated atom [27]. If the atomic wavefiinctions are known, tire pseudo-wavefiinction can be constmcted by removing the nodal stmcture of the wavefiinction. For example, if one considers a valence... 

The importance of surface science is most often exliibited in studies of adsorption on surfaces, especially in regards to teclmological applications. Adsorption is the first step in any surface chemical reaction or film-growdi process. The mechanisms of adsorption and the properties of adsorbate-covered surfaces are discussed in section Al.7.3. 

Wlien a surface is exposed to a gas, the molecules can adsorb, or stick, to the surface. Adsorption is an extremely important process, as it is the first step in any surface chemical reaction. Some of die aspects of adsorption that surface science is concerned with include the mechanisms and kinetics of adsorption, the atomic bonding sites of adsorbates and the chemical reactions that occur with adsorbed molecules. 

A DIET process involves tliree steps (1) an initial electronic excitation, (2) an electronic rearrangement to fonn a repulsive state and (3) emission of a particle from the surface. The first step can be a direct excitation to an antibondmg state, but more frequently it is simply the removal of a bound electron. In the second step, the surface electronic structure rearranges itself to fonn a repulsive state. This rearrangement could be, for example, the decay of a valence band electron to fill a hole created in step (1). The repulsive state must have a sufficiently long lifetime that the products can desorb from the surface before the state decays. Finally, during the emission step, the particle can interact with the surface in ways that perturb its trajectory. 

Now let tj approach t. Then, by the result of the first step, the first factor on the right-hand side vanishes. Hence,... 

The first step is to divide the total potential into two parts a reference part and the remainder treated as a perturbation. A coupling parameter X is introduced to serve as a switch which turns the perturbation on or off. 

The fomiation of molecules was the first step toward local gravitational collapses which led to, among other things, the production of this encyclopedia. 

The initial step in alkane hydrogenolysis is the dissoeiative adsorption, or reaetive stieking of the alkane. One might suspeet that this first step may be the key to the stnieture sensitivity of this reaetion over Ni surfaees. Indeed, the reaetive stieking of alkanes has been shown to depend markedly on surfaee stnieture... 

The first step consists of the molecular adsorption of CO. The second step is the dissociation of O2 to yield two adsorbed oxygen atoms. The third step is the reaction of an adsorbed CO molecule with an adsorbed oxygen atom to fonn a CO2 molecule that, at room temperature and higher, desorbs upon fomiation. To simplify matters, this desorption step is not included. This sequence of steps depicts a Langmuir-Hinshelwood mechanism, whereby reaction occurs between two adsorbed species (as opposed to an Eley-Rideal mechanism, whereby reaction occurs between one adsorbed species and one gas phase species). The role of surface science studies in fomuilating the CO oxidation mechanism was prominent. 

Modem photochemistry (IR, UV or VIS) is induced by coherent or incoherent radiative excitation processes [4, 5, 6 and 7]. The first step within a photochemical process is of course a preparation step within our conceptual framework, in which time-dependent states are generated that possibly show IVR. In an ideal scenario, energy from a laser would be deposited in a spatially localized, large amplitude vibrational motion of the reacting molecular system, which would then possibly lead to the cleavage of selected chemical bonds. This is basically the central idea behind the concepts for a mode selective chemistry , introduced in the late 1970s [127], and has continuously received much attention [10, 117. 122. 128. 129. 130. 131. 132. 133. 134... 

The reactant P is again taken as a pool chemical, so the first step has a constant rate. The rate of the second step depends on the concentration of the intennediate A and on the temperature T and this step is taken as exothennic. (In the simplest case, is taken to be independent of T and the first step is thennoneutral.) Again, the steady state is found to be nnstable over a range of parameter values, with oscillations being observed. 

Double potential steps are usefiil to investigate the kinetics of homogeneous chemical reactions following electron transfer. In this case, after the first step—raising to a potential where the reduction of O to occurs under diffrision control—the potential is stepped back after a period i, to a value where tlie reduction of O is mass-transport controlled. The two transients can then be compared and tlie kinetic infomiation obtained by lookmg at the ratio of... 

Peteanu L A, Schoenlein R W, Wang Q, Mathles R A and Shank C V 1993 The first step In vision occurs In femtoseconds complete blue and red spectral studies Proc. Natl Acad. Sc/. USA 90 11 762-6... 

Schoenlein R W, Peteanu LA, Mathies R A and Shank C V 1991 The first step in vision femtosecond isomerization of rhodopsin Sc/ence 254 412-15... 

A first step towards a systematic improvement over DFT in a local region is the method of Aberenkov et al [189]. who calculated a correlated wavefiinction embedded in a DFT host. However, this is achieved using an analytic embedding potential fiinction fitted to DFT results on an indented crystal. One must be cautious using a bare indented crystal to represent the surroundings, since the density at the surface of the indented crystal will have inappropriate Friedel oscillations inside and decay behaviour at the indented surface not present in the real crystal. 

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