Compact Solids

Thin plates, disks, or sheets of various materials, e. g., polymers, crystals, glasses, paper, cellophane, textile goods, leaves, or microscopic sections, are prepared for spectroscopic examination by being fixed between two frames that are fitted for use in typical sample holders. If the dimensions of the samples are very small, they must be positioned between two silica plates. Spectrophotometers that are fitted with a second sample holder directly in front of the end-on multiplier, (i. e., a multiplier located near the entrance of light in the silica window of the tube) are quite useful. Thus, the stray light can also be included in the detector. 

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Branching occurs to some extent and can be controlled. Minimum branching results in a high-density polyethylene because of its closely packed molecular chains. More branching gives a less compact solid known as low-density polyethylene. 

Depression method. At locations where natural or artificial depressions exist, it is often possible to use them effectively for land-filling operations. Canyons, ravines, dty borrow pits, and quarries have oeen used for this purpose. The techniques to place and compact solid wastes in depression landfills vary with the geometiy of the site, the characteristics of the cover material, the hydrology and geology of the site, and access of the site. 

Komddie, /, comedy, kompakt, a. compact, solid, firm, rugged. Kompendium, n. compendium, abridgment, summary, abstract,... 

Later we will describe both oxidation and reduction processes that are in agreement with the electrochemically stimulated conformational relaxation (ESCR) model presented at the end of the chapter. In a neutral state, most of the conducting polymers are an amorphous cross-linked network (Fig. 3). The linear chains between cross-linking points have strong van der Waals intrachain and interchain interactions, giving a compact solid [Fig. 14(a)]. By oxidation of the neutral chains, electrons are extracted from the chains. At the polymer/solution interface, positive radical cations (polarons) accumulate along the polymeric chains. The same density of counter-ions accumulates on the solution side. 

In spatial dimensions or in partial volumes of compact solids, or... 

Table 8 Typical Properties of Some Common Drugs and Excipients Determined at a Compact Solid fraction of 0.8 to 0.9...

The visual observation of the condenser coils shows, in the visible zone, a compact solid, glassy structure. Inclusions of permanent gasses resulting in snow like surfaces were not seen. 

A high vacuum laser ion source is combined with a dynamic (ToF-MS) or static mass spectrometer (Mattauch-Herzog instrument) for the separation of the ion beams formed and used in LIMS for multi-element major, minor and trace analysis of compact solid samples (bulk analysis).74... 

Powders are porous materials and their bulk and relative densities can change with consolidation (6). However, a powder s true density is the density of its solid phase only and thus is independent of the state of consolidation. The true density of organic excipients typically ranges from 1.0 to 1.6g/cm3 while inorganic excipients (e.g., calcium phosphate) show values greater than 2g/cm3. True density is used to determine powder or compact solid fraction (SF) (see below) and it may be a consideration when selecting excipients if segregation is a concern. True density is often determined by gas pycnometry. 

We now analyze mechanical-displacement flow in a straight channel of constant cross-sectional area, as shown in Fig. 4.11 (with the upper plate at rest). A column of compacted solids of length L is compressed between two rams. The one on the left exerts a force Fo on the solids and it is opposed by a smaller force FL on the right. Thus, friction on the channel walls also opposes the applied resultant force. 

A differential force balance with the following assumptions (a) the compacted solids are either at a steady motion or in a state of incipient slip on the wall (friction at the wall is fully mobilized) (b) axial and radial stresses vary only with the axial distance x (c) the ratio of the radial-to-axial stresses is a constant K, independent of location (d) the coefficient of friction is constant and independent of compaction and (e) temperature effects in the case of steady motion are negligible, results in... 

If the initial solid substance is a chemical compound (an intermetallic, a silicide, etc), then its oxidation can proceed via two different mechanisms, depending on the experimental conditions. Two oxides are formed in the severe oxidation (combustion) usually resulting in the disintegration of the compact solid phase. In the partial (soft) oxidation the chemical compound undergoes a partial decomposition giving another chemical compound of the same class and an oxide. 

Brendle, M. and Colin, G., The Frictional and Transfer Behaviour of Compacted Solid Lubricants on Smooth Metallic Surfaces, Proc. 7th Leeds/Lyon Symp. Friction and Traction, Leeds, 1980. 

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