Site types

Site Type of soil Average general penetration (mm/y) 1 -37 m 0-61 m ... 

A kinetic model which accounts for a multiplicity of active centres on supported catalysts has recently been developed. Computer simulations have been used to mechanistically validate the model and examine the effects on Its parameters by varying the nature of the distrlbultons, the order of deactivation, and the number of site types. The model adequately represents both first and second order deactivating polymerizations. Simulation results have been used to assist the interpretation of experimental results for the MgCl /EB/TlCl /TEA catalyst suggesting that... 

Figure 7 shows bands, obtained like those of Figure 4 by fractional subtraction of the NO bands obtained In the absence of Co. These residual bands did not resemble the bands of NO/Co seen In the absence of Mo as well as did those obtained for the Aero 1000 series. Greater variety In site types, reflecting sulfide neighbors or Increased metal-metal Interaction, evidently exists on sulfided catalysts. 

The acid-site types were examined by IR spectroscopy of adsorbed pyridine. For... 

The database provides project profiles that include site background information (e.g., site type, climate, and precipitation), project information (e.g., purpose, scale, and status), cover information (e.g., design, vegetation, and installation), performance and cost information, points of contact, and references. Table 25.5 provides a summary of key information from the database for 34 recent projects with monolithic ET or capillary barrier ET covers.15... 

Site Name and Location Site Type Status of Project Date Installed... 

Site Smuggler Mountain, CO Site type (Mining) Palmerton, PA (Smelter) Jasper County, MO (Smelter) Murray Smelter, UT (Smelter) ... 

Active ingredient Approved product for organic production Examples of pests controlled Major use sites Type of pesticide... 

The Xj is a relative population of adsorption site of type i in the sample and cmax is the Cu+ ions concentration in the sample of the catalyst related to its volume V. F is the rate of flow of the carrier gas, e is a porosity of the layer of the catalyst bed. p is the rate of temperature change. The populations of the Cu+ site types and both desorption energies and desorption entropies for all Cu+ site types were optimized to obtain the best fit with the experimental data. All three experimental Cu-K-FER TPD curves were fitted at once together with all Cu-Na-FER previously measured TPD curves constraining the parameters AHads i and ASads,i to be the same for all samples. 

Due to the presence of low-temperature desorption peak a new desorption site was included to phenomenological model of TPD experiments previously used for the description of the Cu-Na-FER samples [5], The fit of experimental TPD curves was performed in order to obtain adsorption energies and populations for individual site types sites denoted A (A1 pair), B (sites in P channel (A1 at T1 or T2)), C (sites in the M channel and intersection (A1 at T3 or T4)) [3] and D (newly introduced site). The new four-site model was able to reproduce experimental TPD curves (Figure 1). The desorption energy of site D is cu. 82 kJ.mol"1. This value is rather close to desorption energy of 84 kJ.mol"1 found for the site B , however, the desorption entropy obtained for sites B and D are rather different -70 J.K. mol 1 and -130 J.K. mol"1 for sites B and D , respectively. We propose that the desorption site D can be attributed to so-called heterogeneous dual-cation site, where the CO molecule is bonded between monovalent copper ion and potassium cation. The sum of the calculated populations of sites B and D (Figure 2) fits well previously published population of B site for the Cu-Na-FER zeolite [3], Because the population of C type sites was... 

In Dzombak and Morel s (1990) development, hydrous ferric oxide holds two site types, one weakly and the other strongly binding. In their uncomplexed forms, the sites are labeled >(w)FeOH and >(s)FeOH the notation > represents bonding to the mineral structure, and (w) and (s) signify the weak and strong sites. 

To cast the equations in general terms, we use the label Ap to represent each type of surface site. In the case of hydrous ferric oxide, there are two such entries, >(w)FeOH and >(s)FeOH. There are Mp total moles of each site type in the system, divided between uncomplexed and complexed sites. This value is the product of the mass (in moles) of the sorbing mineral and the site density (moles of sites per mole of mineral) for each site type. 

It is useful to compare the capacity for each metal to be sorbed (the amount of each that could sorb if it occupied every surface site) with the metal concentrations in solution. To calculate the capacities, we take into account the amount of ferric precipitate formed in the calculation (0.89 mmol), the number of moles of strongly and weakly binding surface sites per mole of precipitate (0.005 and 0.2, respectively, according to the surface complexation model), and the site types that accept each metal [As(OH)4 and ASO4 sorb on weak sites only, whereas Pb++, Cu++, and Zn++ sorb on both strong and weak]. 

Figure 2. Evolution of diffusive (Jm, continuous line) and internalisation (/u, circles) fluxes with time for a system with two internalisation sites (Section 2.1.2). Fraction of coverages of each site type, 81 and 82, are indicated with dashed lines. Parameters Dm = 10-9m2 s 1,= l(E4molm 3,r0 = l(E4m,Km,i = l(E5molm 3, Am,2 = 10 3 molm 3,rmax,i = 10 8molm 2,rmax,2 = 10 n molm 2, i = 10 2s 1 and kj = 1 s 1...

In the range of linear adsorption behaviour, whatever the number of site types (see Section 2.3.1 for the merging of parameters of two sites), the surface concentration F is related to via an effective linear coefficient, Ah, while the first-order internalisation processes can also be described by an effective first-order constant, k. Thus, equation (39) can be recast, for instance, in terms of r as ... 

If, on the timescale of observation, the degree of coverage of any site type becomes appreciable, the precise nature of the relationship between Fi, F2 and has to be taken into account. For the case of a Langmuirian isotherm (implying sufficiently fast kinetics of adsorption/desorption) this means that equations in (2) are applicable. Two particular cases are described here ... 

In their description of metal ion adsorption, Benjamin and Leckie used an apparent adsorption reaction which included a generic relationship between the removal of a metal ion from solution and the release of protons. The macroscopic proton coefficient was given a constant value, suggesting that x was uniform for all site types and all intensities of metal ion/oxide surface site interaction. Because the numerical value of x is a fundamental part of the determination of K, discussions of surface site heterogeneity, which are formulated in terms similar to Equation 4, cannot be decoupled from observations of the response of x to pH and adsorption density. As will be discussed later, It is not the general concept of surface-site heterogeneity which is affected by what is known of x> instead, it is the specific details of the relationship between K, pH and T which is altered. 

According to an analysis performed by Ferro and Cacciamani (2002), the preferential site occupancies observed in MgCu2-type phases are summarized in Table 3.8. The atoms preferentially present in each site type are indicated. 

A wide range of reversible adsorption kinetic rates was also found by TIR/FRAP for another protein, lysozyme, on a substrate with a different surface charge, alkylated silicon oxide.(61) It is possible that the wide range of rates results from a spectrum of surface binding site types and/or formation of multilayers of adsorbed protein. 

ANTIBODY-HAPTEN INTERACTIONS TYPE 1, 2, 3 COPPER BINDING SITES Type I dehydrogenase,... 

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