Packing density ratio

Figure 4.13. Effect of Ru packing density on the potentiostatic oxidation of chemisorbed CH3OH at 0.3 V vs. RHE in 0.5 M H2SO4. Legend Packing density (ratio between nr. of surface Ru atoms per Pt surface atoms) in % 14, 35 and 53 [91]. (Reproduced with permission from J Am Chem Soc 2002 124 468-73. Copyright 2002 American Chemical Society.)...

In the past, insufficient attention has been given to the correct choice of bulk density. For example. Fig. 2 shows the bulk density as a function of major consolidation pressure for a typical coal sample. The solids density of the coal has been measured at 1300 kg/m. Hence the packing density ratio may be computed as the ratio of bulk density to solids density. 

The PETN Detonation Pressure, P (also called the CJ Pressure), is shown as a function of packing density in Table 7 and in Fig 4. Note that the measured P values in Fig 4 lie quite close to the theoretical curve developed by Lee Homig (Ref 72), which is based on a Wilkin s type equation of state (see Vol 4, D294-L) with a Grueneisen ratio, r, for the detonation products, that is solely a function of specific volume. Shea et al obtained an effective T = 8.077 p-12.288 (Ref 74)... 

The flow pattern of fluids in gas-liquid-solid (catalyst) reactors is often far from ideal. Special care must be taken to avoid by-passing of the catalyst particles near the reactor walls, where the packing density of the catalyst pellets is lower than in the centre of the bed. By-passing becomes negligible if the ratio of reactor to particles diameter is larger than 10 a ratio of 20 is recommended. Flow maldistributions might be serious in the case of shallow beds. Special devices must be used to equalize the velocity over the cross-section of the reactor before reactants are introduced onto the catalyst bed. 

Figure 33. Dimensionless spoutdiametersasafunctionof dimensionless height for small columns. Case A test case Case B all dimensionless parameters matched, bed diameter halved Case C particle Reynolds number mismatched Case D Froude number mismatched Case E density ratio, Reynolds number mismatched Case F bed Reynolds number mismatched Case G internal friction angle, loose packed voidage mismatched. (From He et al., 1995.)...

Figure 2. Auger signal ratios and packing densities of NA adsorbed at Pt(lll). Experimental conditions adsorption from 10 mM KF adjusted to pH 7 with HF, followed by rinsing with 1 mM HF (pH 3.3) temperature, 23 1 C electron beam at normal incidence, 100 nA, 2000 eV. A. Auger signal ratios 0(/Ipt) and (Ipt/Ip,) for NA adsorbed at -0.2 V vs. Ag/AgCl reference. B. Packing density of NA adsorbed at —0.2 V. Continued on next page.

Figure 5. OH-CH signal ratio (EELS) and packing density (Auger) of NA adsorbed at Pt(lll) vs. electrode potential. A. Ratio of EELS O-H (3566 cm-1) to C-H (3068 cm-1) peak height. B. Packing density of K+ ions. Experimental conditions (A) adsorption from 1 mM NA in 10 mM KF at pH 7, followed by rinsing in 2 mM HF (pH 3) (B) adsorption from 1 mM NA in 10 mM KF at pH 3, followed by rinsing with 0.1 mM KOH (pH 10). EELS conditions as in Figure 4 Auger conditions as in Figure 2.

Intuitively, one would expect a volume contraction on forming a strongly bonded compound from the elements. Indeed, Richards 190, 191) regarded heats of formation as heats of compression. The fractional volume contraction, AV = (molecular volume - 2 atomic vol-ume)/2(atomic volume), has been related to formation heats for NaCl or CsCl type structures 151). Even nonpolar compounds in the condensed state cohere in close-packed arrays. The packing density of difluorine, derived from the ratio of the van der Waals envelope to the molecular volume, is especially low, and a larger contraction would be expected for fluorides than for other halides. This approach has yet to be systematically examined. 

The interlayer region of LDHs can provide a novel environment for photochemical reactions of guest molecules [201-204]. For example, Takagi et al. reported that the controlled photodimerization of a variety of unsaturated carboxylate species intercalated in the interlayer galleries of Mg/Al LDH could occur between the layers [203]. Syn head-to-head cyclodimers were selectively formed in the irradiation of intercalated cinnamate ions, whereas two isomers of syn head-to-head and syn head-to-taU cyclodimers were formed for the case of phenylethenylbenzoates. The product selectivity was shown to be controlled by the Mg/Al ratio of the host LDH, and hence the packing density of the anions in the interlayer region [204]. 

The coercive force of a powder is an extrinsic property, which is influenced by many factors such as size and shape and packing density. Maghemite particles prepared from directly precipitated spindle-type hematite particles showed a tendency of increase in coercive force with decrease in particle size, and increase in their aspect ratios (31). However, a quantitative relationship between the coercive force and size and/or aspect ratio is still not available. 

Aluminized expls exhibit a decrease in performance as their packing density approaches theoretical maximum density (TMD). This effect is more pronounced in compns of high A1 content. Table 9 (from Ref 17) shows equivalent weight ratios (WQd) and relative bubble energies (RBE) of two aluminized expls as a function of %TMD... 

It can be shown that the ratio v3lvg is equal to the ratio of polymer packing densities coefficients in the amorphous and crystalline states, KJKC at Tg, because, by definition, Ka = NA V /va and Kc - NA Vi/yC)where vj is the Van der Waals volume of the chain repeat unit. The calculated values of (ATc)g correlate with the characteristic chain parameter a/o, the relationship between them being expressed by a linear equation... 

Lu Packed Density. Accdg to MIL-STD-1233, Method 400, the packed d of a powdered material is the weight per unit volume of material which has been packed until it has attained the most compact form. Packed d indicates the loading d of loose pyrotechnic powders (See also item E) Relative Density (d ). It is the ratio of the absolute d at t°C to abs d of water at 3.98°C (0.999973 g/cu cm, its maximum d) and is expressed as g/ml. It is also called "density (or specific graviry) relative to water at 4°C ... 

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