Useless component

The recovery, regeneration, and repeated reuse of the active catalyst are of prime importance in substantially reducing the overall cost of coal liquefaction. The used catalysts usually remain in the bottoms products, which consist of nondistillable asphaltenes, preasphaltenes, unreacted coal, and minerals. The asphaltenes and preasphaltenes can be recycled with the catalyst in bottoms recycle processes. However, unreacted coal and minerals, if present in the recycle, dilute the catalyst and limit the amount of allowable bottoms recycle because they unnecessarily increase the slurry viscosity and corrosion problems. Hence, these useless components should be removed or at least reduced in concentration. If the catalyst is deactivated, reactivation becomes necessary before reuse. Thus, the design of means for catalyst regeneration and recycle is necessary for an effective coal liquefaction process. Several approaches to achieving these goals are discussed below. 

It is not an exaggeration to say that the evaluation of mechanical separation process/equipment is performed based on the conception of yield and quality. For example, the widely used Newton efficiency is defined in the following manner. In the case of better separator, both the yield and the degree of quality improvement should have higher values. From another viewpoint, the recovery rate of useful component should have a higher value, and the intermix rate of the useless component into product should have lower values for the better separator. In other words, this definition is based on the concept that for a better separator,... 

This definition is based on the consideration that the recovery rate of both the useful and useless components should have a higher value for a good separator. 

Value of the fraction of useful component full range. (The same result is obtained by reversing the viewpoints with regard to not only the useful and useless components but also the product and the residuum.)... 

It is interesting to note that the Voigt model is useless to describe a relaxation experiment. In the latter a constant strain was introduced instantaneously. Only an infinite force could deform the viscous component of the Voigt model instantaneously. By constrast, the Maxwell model can be used to describe a creep experiment. Equation (3.56) is the fundamental differential equation of the Maxwell model. Applied to a creep experiment, da/dt = 0 and the equation becomes... 

Because oxides are usually quite brittle at the temperatures encountered on a turbine blade surface, they can crack, especially when the temperature of the blade changes and differential thermal contraction and expansion stresses are set up between alloy and oxide. These can act as ideal nucleation centres for thermal fatigue cracks and, because oxide layers in nickel alloys are stuck well to the underlying alloy (they would be useless if they were not), the crack can spread into the alloy itself (Fig. 22.3). The properties of the oxide film are thus very important in affecting the fatigue properties of the whole component. 

In contrast molecular interaction kinetic studies can explain and predict changes that are brought about by modifying the composition of either or both phases and, thus, could be used to optimize separations from basic retention data. Interaction kinetics can also take into account molecular association, either between components or with themselves, and contained in one or both the phases. Nevertheless, to use volume fraction data to predict retention, values for the distribution coefficients of each solute between the pure phases themselves are required. At this time, the interaction kinetic theory is as useless as thermodynamics for predicting specific distribution coefficients and absolute values for retention. Nevertheless, it does provide a rational basis on which to explain the effect of mixed solvents on solute retention. 

The beating of a faint source with a high power coherent source is a well known process to detect its phase and amplitude. The same detection equipment allows the evaluation of the power of the source with theoretical limits similar to a noiseless photon counter. Such detection apparatus are limited by the bandwidth of the electronic component as this bandwidth is rapidly increasing, this may be a competitive solution for quantum limited detection in the far infra red. The phase of a thermal source is an useless information ... 

The material presented here is a compilation obtained by critically screening approximately 20,000 references from the literature (mainly from the Petroleum Abstracts Data Base and Patent Data Bases). Only materials that are accessible to the public have been included. The literature was screened from a chemist s point of view. Unfortunately several papers and patents did not disclose the chemical nature of the additives that are proposed for certain applications. In most cases it was not possible to learn the components by looking up cross-references and other sources. Papers of this kind are useless and have been omitted from the reference list. Research and procedures that are obviously not working, as well as wonder additives that are supposedly good for everything you can imagine, have also been left out. 

During catabolic and anabolic processes, a renovation of the molecular cellular components takes place. It should be emphasized that the catabolic and anabolic pathways are independent of each other. Be these pathways coincident and differing in the cycle direction only, the metabolism would have been side-tracked to the so-called useless, or futile, cycles. Such cycles arise in pathology, where a useless turnover of metabolites may occur. To avoid this undesirable contingency, the synthetic and degradative routes in the cell are most commonly separated in space. For example, the oxidation of fatty acids occurs in the mitochondria, while the synthesis thereof proceeds extramitochondrially, in the microsomes. 

The presence of the triethylamine has severely compromised the ability of the mass spectrometer to see the components of interest in the mixture. The triethylamine analysis is not entirely useless, as the UV-visible chromatogram permits knowing where in the TIC chromatogram to look for features of interest. Not being able to use the TIC chromatogram, however, compromises the value of the determination. 

The concentration dependence of z/l vs. c/c0 is plotted in Figure 11.14a. It can be seen that from a Thiele modulus cp > 3 the educt does not reach the internal part of the pore. The inner part of the pore system is useless for catalysis. This is especially relevant if expensive metals serve as active components on a porous carrier, which are then wasted. There are chances to master this diffusion limitation, which will be discussed later in detail. Another important variable is the efficiency factor tj. The efficiency factor r is defined as the quotient of the speed of reaction rs to the maximal possible speed of reaction rsmax. r is related to q> as the quotient of the hyperbolic tangent of the Thiele modulus qy. 

The operation of magnetic sector (Chap. 4.3), linear quadrupole (Chap. 4.4), or quadrupole ion trap (Chap. 4.5) mass spectrometers in the repetitive scanning mode is useful for the identification of the components of a mixture. If quantitation is a major issue (below), selected ion monitoring (SIM) is preferably employed the term multiple ion detection (MID) and some others are also in use. [33] In the SIM mode, the mass analyzer is operated in a way that it alternately acquires only the ionic masses of interest, i.e. it jumps from one m/z value to the next. [34-39] The information obtained from a SIM trace is equivalent to that from a RIC, but no mass spectra are recorded. Thus, the scan time spent on a diagnostically useless m/z range is almost reduced to zero, whereas the detector time for the ions of interest is increased by a factor of 10-100. [40] An analogous improvement in sensitivity (Chap. 5.2.3) is also observed. 

If the simulation doesn t show the model accurately reflecting the component s behavior, this does not necessarily mean the model is useless or wrong (although this is a possibility). People make models to model different aspects of a part and sometimes only cover a subset of the full operating or temperature range. For example, some models may have only AC characteristics modeled accurately and not the transient performance. 

Selectivity means the ability to discriminate one particular element from the others. Innumerable highly sensitive reactions exist which are useless because of the interfering action of other components. Accuracy is an obvious necessity, but it means much more than simple reproducibility on known samples. 

Using simple laboratory equipment, it is possible to detect variations of the density of the order of 1 kg m-3 therefore, density measurements would be useless for diglycidyl ether of bisphenol A and diamino diphenyl methane (DGEBA-DDM), because both components have close Ma values. They would be moderately sensitive for unsaturated polyesters of maleate/ phthalate (1/1) of propylene glycol crosslinked by styrene (36 wt%), and relatively sensitive for DGEBA cured by diamino diphenyl sulphone (DDS) or phthalic anhydride (PA), for which relative variations of the molar ratio y of about 5% could be detected. In certain cases, where some comonomer (PA or styrene) can be lost by evaporation during the cure, density measurements can constitute a simple and efficient method of control way (e.g., for non-filled materials). 

The key feature of photosynthesis is the ability to carry charge spatially away from an excited state reaction centre before the usually highly efficient and biochemically useless recombination can take place. In photosynthetic systems, charge separation occurs about 108 times faster than recombination, a ratio that is impossible to reach in normal chemical reactions. This phenomenon is achieved by the spatial anchoring of the components at particular orientations to one another within a non polar region of the membrane anchored protein, thus preventing free diffusion and allowing a vectorial uphill chemical reaction. 

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