Bulk concentration major

However, surface segregation (cs / Cb) has a radical effect on AE, as can clearly be seen in Fig. 6.3(b). Cu/Ni alloys are known (Kelley and Ponec 1981, Ouannasser et al 1997) to have an enriched Cu concentration in the surface layer for all bulk concentrations. As a result, the alloy shows a more Cu-like behaviour than it would if it were non-segregated. In particular, AE has a value significantly closer to that for pure Cu than in the case where cs = Cb, and this occurs at all bulk concentrations c. The smallest change in AE occurs in Cu-rich alloys, which is understandable, because these alloys have mostly Cu in the surface layer anyway, so the effect of surface segregation is relatively small. Thus, surface segregation has a lesser effect in these alloys than in Ni-rich ones, which have mostly Ni in the bulk, but may have a Cu majority in the surface layer. Clearly, then, the concentration cs of the surface layer is the primary parameter in determining the chemisorption properties of the DBA. 

The model discretization or the number of collocation points necessary for accurate representation of the profiles within the reactor bed has a major effect on the dimensionality and thus the solution time of the resulting model. As previously discussed, radial collocation with one interior collocation point generally adequately accounts for radial thermal gradients without increasing the dimensionality of the system. However, multipoint radial collocation may be necessary to describe radial concentration profiles. The analysis of Section VI,E shows that, even with very high radial mass Peclet numbers, the radial concentration is nearly uniform and that the axial bulk concentration and radial and axial temperatures are nearly unaffected by assuming uniform radial concentration. Thus model dimensionality can be kept to a minimum by also performing the radial concentration collocation with one interior collocation point. 

The majority of studies examining natural variability or experimental manipulation suggest the response to specific DOM components (known or presumed) is much stronger than the response to changes in bulk concentrations. These findings underscore the need to identify which components of DOM are generating the metabolic heterogeneity we observe in the real world. 

Because surface binding causes bulk concentration depletion, protein solution was flowed continuously through the channels until the bulk concentration became stabile. This required an aliquot roughly equal to 4 or 5 times the channel volume in the microchannels with the lowest protein concentration, while the highest concentration channels required considerably less flow, as expected. A line profile generated from the epifluorescence image of these channels is shown in Fig. 6.10b. The majority of the signal emanated from the bulk. 

Equation (20) is an approximation being valid only in the depletion layer, where the majority carrier density at the surface (ns for n-type ps for p-type) is smaller than the corresponding bulk concentration. The thickness of the space charge layer can be defined by the relation dsc = eeo/C which is valid for a normal capacitor. Inserting Eq. (20), for the thickness of the space charge layer, one obtains ... 

GD-MS is of use for the direct determination of major, minor and trace bulk concentrations in electrically-conductive and semi-conductor solids down to concentrations of 1 ng/g. Because of the limited ablation (10-1000 nm/s), the analysis times especially when samples are inhomogeneous are long. It has been applied specifically to the characterization of materials such as Al, Cd, Ga, In, Si, Te, GaAs and CdTe. 

The center range, where the capacity curve is rather flat, i.s characterized by a majority carrier density being depleted with respect to the bulk concentration, i.e. Ms < (j (depletion region) whereas tig pg. In this range the capacity is mainly determined by the linear term in Eq. (5.24) which originates from the ionized donors. 

Bidk vanadium pentaoxide is quite active but low selective catalyst of hydrocaibons partial oxidation. It was established by XRD that the higher content of the phosphorus additive in it [12] the weaker peaks attributed to V2O) in bulk catalysts and, simultaneously, P-VOPO4 phase reflections appeared. The latter became the major component of VPO catalyst at fp > 0.67. The constituents of the prepared sample were found to be also 6 0)2P207, VO(POj)2 and some amorphous compounds. At this takes place, all the cations were considered by authors [12] to be bonded in vanadyl groiqis V=0 and phosphorus atoms form Bronsted acidic center each. It has been found an increased concentration of phosphorus over the surface as compared to the biilk and the higher phosphorus content in the sample the grown bulk concentration of the reduced vanadium ions were observed. 

The nature of the surfactant polar groups can influence the nucleation process in two major ways. The polar groups may serve as sites for heterogeneous nucleation this effect would be specific to particular surfactant-solid combinations. Adsorption and/or complexation of the reactant species by the polar groups will result in changes in the local concentrations at the interface and in the bulk of the water pool. Complexation will reduce the bulk concentration of the reactant species, and for nucleation within the water pool this will have the effect of decreasing the tendency toward nucleation (see Fig. 5f). 

It is well known that resins are good dispersing agents for asphaltenes in crude oil. From previous results, the resin films are not strongly influenced by bulk concentration or the nature of the spreading solvent. Hence, it is of major interest to study mixed films of resins and asphaltenes. Figure 5 shows the surfaee eoncentration of asphaltene/resin mixtures necessary to aehieve a surface pressure equal to 10 mN/m, when both solvent aromaticity and bulk concentration of resins are varied with the bulk concentration of asphaltenes is fixed (4mg/ml). 

The ISP consumes virtually all the world s production of bulk concentrates, materials that usually contain 45-60% of zinc plus lead and with at least 10% of each metal. The ability of the ISP to accept bulk concentrates was a major factor in determining the viability of the McArthur River mine in Australia. Tests over many years had been unable to determine a method of separating the zinc and lead in the ore with accqrtable recoveries. However, much better recoveries could be obtained if a bulk concentrate was produced. Table II shows the results of flotation tests to produce selective and bulk concentrates, as given in the paper by Lee etal.(3). 

The development of the mine to produce bulk concentrates and the need for assured outlets for a major part of its ouq>ut led to the decision of Mount Isa Mines Ltd. to acquire the Avonmouth and Duisburg ISP smelters. 

Since the lead smelter owned by OAO Kazzinc has ten years of experience in smelting lead-zinc sulphide concentrates by the Kivcet technology, a method of comparing physical and chemical properties of the bulk concentrate to the characteristics of typical lead-zinc raw materials has been developed. This method was used to decide on the feed composition and process operating conditions. Two major features of the bulk concentrate that affect the results of the smelting in the Kivcet unit were examined the calorific value and the desulphurization rate. 

A space-charge region is also formed, and the bands bent, when a potential is apphed to the electrode. As above, the band edges remain pinned at the electrode/solution interface, which arises because the potential drop between the bulk semiconductor and the solution is essentially entirely across the space-charge region rather than at the semiconductor interface. As a consequence, the intrinsic electron transfer rate constant is independent of applied potential. Nevertheless the current (and hence the effective rate constant) does depend on the apphed potential because the concentration of electrons (the majority carriers) at the electrode surface relative to its bulk concentration has a Boltzmann dependence on the energy difference between the band edge and the interior of the electrode. (The Fermi Dirac distribution reduces to a Boltzmann distribution when E > Fp-)... 

The capacity-potential relation, given by Eq. (10), is the so-called Mott-Schottky equation which is strictly valid only in the exhaustion region, i.e., for space charges in which the majority carrier density at the surface is smaller than the corresponding bulk concentration < o for n-type and Ps < po for p-type electrodes). 

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