Mid-range order

Another remarkable result are the differences between materials that were treated by different methods in order to extract the silica (Fig. 2, d, e, f) the treatments clearly affect their SiK edge XANES spectra, i.e. the materials differ in mid-range order. Infrared spectra (not shown here) support these findings. So, our idea of treating the biological materials as mildly as possible is justified. Former analytical investigations on the solid-state properties of biogenic silica may not have considered this aspect sufficiently. 

The detection of mid-range order at a length scale of 4-10 A in biogenic silicas is of special significance since it is generally assumed that the biominerals are templated by biological macromolecules, e.g. peptides, proteins or polymeric hydrocarbons [15]. The repetitive units of these macromolecules have characteristic length scales of 4-10 A. 

Blast resistant doors arc not "off the shelf items, They are built to order and manufacturers generally require 6 to 8 weeks after notification of approval of the shop drawings and design data to schedule and fabricate low-range doors, 10-12 weeks for mid-range doors, and 12 weeks or more for high-range doors. 

Macroscopic experiments allow determination of the capacitances, potentials, and binding constants by fitting titration data to a particular model of the surface complexation reaction [105,106,110-121] however, this approach does not allow direct microscopic determination of the inter-layer spacing or the dielectric constant in the inter-layer region. While discrimination between inner-sphere and outer-sphere sorption complexes may be presumed from macroscopic experiments [122,123], direct determination of the structure and nature of surface complexes and the structure of the diffuse layer is not possible by these methods alone [40,124]. Nor is it clear that ideas from the chemistry of isolated species in solution (e.g., outer-vs. inner-sphere complexes) are directly transferable to the surface layer or if additional short- to mid-range structural ordering is important. Instead, in situ (in the presence of bulk water) molecular-scale probes such as X-ray absorption fine structure spectroscopy (XAFS) and X-ray standing wave (XSW) methods are needed to provide this information (see Section 3.4). To date, however, there have been very few molecular-scale experimental studies of the EDL at the metal oxide-aqueous solution interface (see, e.g., [125,126]). 

We must, of course, have a value of in order to be able to use these equations for the calculation of the room temperature rate constant ky If we only require a rough estimation of kj then we can assume a mid-range value of E, say 75 kj mol, for these calculations. 

Only short-range ordering and dislocation phenomena should be seen in the mid-infrared spectral region. Far infrared spectroscopy should yield interesting information on long-range order and dislocation phenomena in zeolite lattices. 

However, this maximum is for a solid phase, wherein spheres are so closely packed that long-range order is preserved and there is little, if any, net diffusion of spheres. For the pure hard-sphere Mid, the upper boxmd on T) is even less the fluid-solid phase transition occurs at ii = 2ii a /3 = 0.494 [12]. For it < 0.494 the substance is fluid and long-range order is disrupted by molecular motions. Without attractive forces between spheres, no vapor-liquid phase transition occurs and we refer to the material at Ti < 0.494 as merely "fluid." The hard-sphere phase diagram is shown in Figure 4.8. 

Absorption maxima are on the order of 530 nm. Strong oscillator strengths are also observed. Series O-R, XIO = N, demonstrated low to moderate pg, excellent f and A, in the range of550 nm. These compounds have variable FOM performance and have moderate pg and mid-range cp values. 

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