Variation of composition

Prussian Blue. Reaction of [Fe(CN)3] with an excess of aqueous h on(Ill) produces the finely divided, intensely blue precipitate Pmssian Blue [1403843-8] (tetrairon(Ill) tris(hexakiscyanoferrate)), Fe4[Fe(CN)3]. Pmssian Blue is identical to Turnbull s Blue, the name which originally was given to the material produced by reaction of [Fe(CN)3] with excess aqueous h on(Il). The soHd contains or has absorbed on its surface a large and variable number of water molecules, potassium ions (if present in the reaction), and h on(Ill) oxide. The h on(Il) centers are low spin and diamagnetic h on(Ill) centers are high spin. Variations of composition and properties result from variations in reaction conditions. Rapid precipitation in the presence of potassium ion affords a colloidal suspension of Pmssian Blue [25869-98-1] which has the approximate composition KFe[Fe(CN)3]. Pmssian Blue compounds are used as pigments in inks and paints and its formation on sensitized paper is utilized in the production of blueprints. 

Composition The law of mass aclion is expressed as a rate in terms of chemical compositions of the participants, so ultimately the variation of composition with time must be found. The composition is determined in terms of a property that is measured by some instrument and cahbrated in terms of composition. Among the measures that have been used are titration, pressure, refractive index, density, chromatography, spectrometry, polarimetry, conduclimetry, absorbance, and magnetic resonance. In some cases the composition may vary linearly with the observed property, but in every case a calibration is needed. Before kinetic analysis is undertaken, the data are converted to composition as a function of time (C, t), or to composition and temperature as functions of time (C, T, t). In a steady CSTR the rate is observed as a function of residence time. 

Kubaschewski and Hopkins consider the conditions of the gaseous phase which influence the rate of corrosion of metals apart from major variations of composition, they refer also to the effects of minor impurities, gas pressure, flow rate and ionisation. 

Fig. 9-13. Analytical data obtained by point-to-point exploration with a microprobe, showing the variation of composition of a copper-zinc alloy in a region of diffusion. (After Castaing and Guinier, Anal. Chem., 25, 724.)...

Furthermore, in the more general case we are concerned with a variation of composition and sequence length distribution not only as a function of retention volume but within each chromatogram area segment (or "slice ) at each retention volume. A significant polydispcrsity of one of these properties within a chromatogram slice can easily invalidate the polymer analysis described above. 

In its basic form, a broad-focussed electron beam probe provides compositional information on a relatively large area (— 1 mm2), to a depth of the order of 1 nm. To obtain information about the variation of composition with depth, controlled... 

Effects of Variation of Composition and Block Sequence on Properties of Copolymers Containing Semicrystalline Block(s)... 

Mai A, HaanappelVAC, UhlenbruckS, TietzF, and Stover D. Ferrite-based perovskites as cathode materials for anode-supported solid oxide fuel cells, Part I. Variation of composition. Solid State Ionics 2006 176 1341-1350. 

Most of the published composition/size distribution data have been obtained by analyzing cascade impactor samples. Some of these data suffer from poor size classification as a result of particle bounce or reentrainment, seriously limiting size resolution. Even when this problem is overcome, the data obtained with conventional cascade impactors are not capable of resolving many details of the distribution of submicron particles. These instruments typically classify only those particles larger than 0.3-0.5 tam aerodynamic diameter. All smaller particles are collected on a filter downstream of the impactor. Some measurements of the variation of composition with size below this limit have been attempted by aerodynamically classifying resuspended ash ( ). These data suffer from incomplete disapregation as well as poor classification of the smaller particles. 

We emphasize that the use of g in these equations may be justified only if /—a, because of the Edwards cancellation theorem (Section 6). We should expect a metal-insulator transition to occur for some value of in the neighbourhood of For several liquid systems there is experimental evidence that the interference term in (52) is absent. Thus for liquid TeTl alloys, with variation of composition and temperature, for a less than the Ioffe-Regel value e2/3hai the conductivity is proportional to the square of the Pauli paramagnetic susceptibility and then to 2. These results are due to Cutler (1977). Warren (1970a, b, 1972a, b) examined... 

The most important character of all of the berthierine compositions is their low silica content. The variation of compositions found for pellets from the recent sediments appears to be the result of the crystallization of a chlorite structure with full octahedral occupancy. The meta-berthierines fall within the limits deduced for synthetic magnesian 7 X chlorites, limits which are also near full octahedral occupancy. 

The only way out of this dilemma, is the conclusion that the equivalent lattice points are occupied indiscriminately by the two types of atom. (A large number of unit cells is concerned in the formation of an X-ray reflection local irregular variations of composition are not detected.) In agreement with this conclusion is the fact that the length of the unit cell edge of such an alloy lies between those of the pure components— indeed, the relation between unit cell size and composition is almost exactly linear. 

The mechanical and thermal properties of a range of poly(ethylene)/ poly(ethylene-propylene) (PE/PEP) copolymers have been examined by Mohajer et al. (1982). They studied the effect of variation of composition and copolymer architecture on the polymer properties by synthesizing a range of PE-PEP-PE and PEP-PE-PEP triblocks and PE-PF.P diblocks with high molecular weights (M > 200 kg mol (.The crystallinity, density and melting enthalpy for all copolymers were found to be linearly dependent on the PE content, indicating microphase separation of PE and rubbery PEP in the solid state. The... 

Now let us consider what is going to happen to the above DMM picture under the variation of composition (chemical substitution) and/or geometry, both reducing the symmetry of the CLS. An interplay between these two types of perturbation is the main concern in the LD theory of ligand influence. 

Homogeneous two-dimensional model This model accounts for radial variation of composition and temperature in the bed that may be present for large heats of reaction. Corresponding material and energy balances are ... 

Fig. II. C. 2 Variation of composition in a nozzle to show transition to frozen flow...

Table 1. Acetylacetone Variation of composition at equilibrium with solvent and the chemical shift of the enol proton, d(OHO)...

All data except for the upper curves of Figures 1 and 5 are described by straight lines, the equations for which are listed in Tables II, III, and IV. Their identification is consistent with that used in the figures. Figure 3 lines are listed as a single composition in Table III, since the precision of measurements did not permit the demonstration of the variation of composition with vapor pressure which... 

A metastable broad single-phase region and many additional phases, termed microphases, are indicated by the measurements. The consecutively numbered data are plotted in the figures. Each curve must represent a different structure and its continuous variation of composition with pressure. In interpreting these results it is assumed, on the basis of experimental evidence, that we are dealing with homogeneous samples and that the system is thermodynamically at equilibrium with respect to a particular microphase structure when each datum point is taken. In addition, a particular microphase structure may be, and frequently is, metastable relative to other closely related structures in the same family or to other structures in different families. 

Recently, a sufficiently exact method to predict conditions at the hot spot has been developed (8>) and therefore the volume averaged conditions can be estimated assuming a linear variation of composition and a parabolic variation of temperature up to the hot spot ... 

Lin et al. [17] studied the dynamics of copolymers adsorbed on an air-water interface. These measurements complemented the static measurements described above and in Fig. 4. The extent of the polymer films perpendicular to the surface is small compared to penetration distance and wavelength so that EWDLS is most sensitive to variation of composition in the plane of the interface. Figure 7 shows the measured normalized autocorrelation I (/) for different surface pressures. Frames a-d were taken during the first compression of the monolayer, and frames e-h were taken during the second compression. The difference between the two sets of measurements is an indication of structural changes induced by compression cycling. The frames e-g can be compared to the data in Fig. 4. The solid lines in the three frames are fits to a sum of two exponential functions, each with a characteristic decay time. The fast decay constant has a characteristic associated with diffusive motion of the disks. The slow decay constant ( several seconds) was ascribed to the dynamics of the associations of disks. 

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