Size matching

Granulation processes offer a number of important advantages. The most significant are decreased pollution problems and the abiUty to produce granules of almost any reasonable size allowing close size matching with granular ammonium phosphates and potassium chloride in the preparation of NPK fertilizers (26). 

Alkaline earth oxides (AEO = MgO, CaO, and SrO) doped with 5 mol% Nd203 have been synthesised either by evaporation of nitrate solutions and decomposition, or by sol-gel method. The samples have been characterised by chemical analysis, specific surface area measurement, XRD, CO2-TPD, and FTIR spectroscopy. Their catalytic properties in propane oxidative dehydrogenation have been studied. According to detailed XRD analyses, solid solution formation took place, leading to structural defects which were agglomerated or dispersed, their relative amounts depending on the preparation procedure and on the alkaline-earth ion size match with Nd3+. Relationships between catalyst synthesis conditions, lattice defects, basicity of the solids and catalytic performance are discussed. 

At variance with the evaporated samples, Am and did not change much for the sol-gel ones, in spite of the difference between AE cation radii size (Fig. lb, c). It can be suggested that the sol-gel method succeeded in better introduction of Nd into a solid solution (supported by the TPD results) which also depended to a lower extent on the cation radii size match. The increase of the lattice anisotropy AO (Fig. Id) and the trend of the local strain values to decrease or remain about constant (Fig. lc) indicated that there was competition between disorder sources of different nature dispersed lattice defects and Nd3+ agglomerates. 

All these methods have found applications in theoretical considerations of numerous problems more or less directly related to solvent extraction. The MM calculated structures and strain energies of cobalt(III) amino acid complexes have been related to the experimental distribution of isomers, their thermodynamic stability, and some kinetic data connected with transition state energies [15]. The influence of steric strain upon chelate stability, the preference of metal ions for ligands forming five- and six-membered chelate rings, the conformational isomerism of macrocyclic ligands, and the size-match selectivity were analyzed [16] as well as the relation between ligand structures, coordination stereochemistry, and the thermodynamic properties of TM complexes [17]. 

The S/N of individual spectra is optimized when each sample is contained within a size-matched RF coil. As mentioned in the introduction to this chapter, this implies that the coils must be small in order for a number of them to fit inside the homogeneous region of the magnet. The first implementation using multiple coils was by MacNamara and co-workers [12], who connected four coils in parallel to make the circuit shown in Figure 8.2.2. 

Size match between host cavity and guest cation. In fact, the flexible [18] crown-6 is a reasonably good size match for all of the alkali metal cations, although it is optimum for K+. 

A striking illustration of the rigidifying, preorganising effects of the three-dimensional cavity of the cryptands may be seen in the data given in Figure 3.37. Clearly, even though the size match is... 

In both the chloride and bromide structures, the halide was also found to be encapsulated, but was positioned more centrally within the cavity, as explained by a better size match between the ligand and halide (Figure 7B) [48], In both cases the cryptand is hexaprotonated and all six of the protonated amines exhibit hydrogen bonding with the internal halide, with average NH—X distances of 3.30 A for chloride and 3.39 A for bromide. The distance between the bridgehead amines is 7.40 A and 7.50 A for the chloride and bromide complexes, respectively. 

Make sure to get the in-line filters with the connector size matching the diameter of the pump tubing. 

We showed experimentally that hydroxydanaidal is the only basis of measure by which the female gauges male size during precopulatory interaction. Females failed to differentiate between males that differed in body mass or PA content if the males lacked hydroxydanaidal, but they chose between males that were size-matched and PA-free, if one of the males was given an experimental subsidy of... 

A chemical reaction can be viewed as a phenomenon dealing with molecular shape (topology) changes. Whether a particular reaction will take place will depend upon whether the product can fit within the space occupied by the reactant. The space occupied by the reactant is the reaction cavity. Since the boundaries of a reaction cavity are undefined in an isotropic solution, size matching of the reactant, products and the reaction cavity is not important in this medium. On the other hand, when the reaction cavity has a well-defined boundary, as in most organized assemblies (especially in solid state), size matching can become important and occasionally may even become the sole factor controlling the feasibility of a reaction (Fig. 8). 

For Rh, the size match with P is better and square antiprismatic cavities are seen for [Rh9(CO)2ip]2" and [Rhi0(CO)22P]3 . Both of these clusters possess 11 skeletal pairs of electrons and obey Wade s rule for nido- and c/oso-clusters, respectively. Arsenic analogues of these compounds are known. 

X-ray fluorescence has been used extensively in air pollution work however, it has not been used much in industrial hygiene work. XRF has one immediate advantage that it is nondestructive. The many limitations in XRF has been the particle size matching of samples to standards. Many laboratories are working on potential corrections both physically or... 

In the sol-gel preparation of supported metals, a metal precursor is usually added directly to the solution prior to gelling. Regardless of whether the metal precursor participates in hydrolysis and/or condensation, it will become part of the network as the gel forms. Thus, any parameters that are important in solution chemistry (Table 1) could affect the properties of the metal upon activation. An example is the work of Zou and Gonzalez [39] cited in Section 2.I.4.3.A. When these authors used water content as a variable to change the pore size distribution of a series of Pt/Si02 catalysts, they found that the particle size distribution of reduced Pt (in the form of crystallites) is also dependent on the hydrolysis ratio. The average Pt particle size nearly doubles (from about 1.7 to 3nm) as the hydrolysis ratio increases from 10 to 60. As noted earlier, the stability of these catalysts, in terms of the resistance of Pt particles towards sintering, is a function of how well the pore diameter and particle size match. 

As discussed in section 3.2, hybrid frameworks provide a unique opportunity to create interesting enantiomerically pure (homochiral), porous networks. One of the motivations for so doing is the possible applications of such networks in the area of chiral separations, which was first demonstrated in 2000 by Rosseinsky and co-workers.83 In more recent work, a homochiral network based upon nickel benzene-1,3,5-tricar-boxylate showed a modest enantiomeric excess (ee) of 8% for the adsorption of a simple naphthol derivative.84 In general, it is found that the enantiomeric discrimination depends upon the relative sizes of the cavities and the sorbate molecules, with better selectivity being found when the size match is close. It also appears that ee values are higher for catalytic applications than chiral separations, as described in the following section. 

The results described in the preceding section indicate that the size-match of a resolving agent and a target racemate is important to achieve high efficiency of... 

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