Residue-packing densities

There are several indications that a crystalline solid is the most appropriate state to model the protein interior (Chothia, 1984). The very fact that protein structures can be determined to high resolution by X-ray diffraction is indicative of the crystalline nature of the protein. Additionally, the packing density and volume properties of amino acid residues in proteins are characteristic of amino acid crystals (Richards, 1974, 1977). In spite of the apparent crystallinity of the protein interior, most model compound studies have investigated either the transfer of compounds from an organic liquid into water (see, for example, Nozaki and Tanford, 1971 Gill et al., 1976 Fauch-ere and Pliska, 1983), or the association of solute molecules in aqueous solution (see, for example, Schellman, 1955 Klotz and Franzen, 1962 Susi et al., 1964 Gill and Noll, 1972). Both these approaches tacitly assume a liquidlike protein interior. 

Miyazawa S, Jernigan RL. Residue-residue potentials with a favorable contact pair term and an unfavorable high packing density term, for simulation and threading. J. Mol. Biol. 1996 256 623-644. 

There are four ways in which ethylene oxide may be retained in products at the end of sterilization cycles. These are as gaseous ethylene oxide, as. ethylene oxide dissolved in water, as ethylene oxide within but not attached to the product or packaging material, and as molecularly adsorbed or absorbed ethylene oxide [13]. The total amount of residual ethylene oxide and the balance among the four forms of residue at the end of sterilization are functions of the sterilization process conditions, the composition of the product, the size of the product, the packaging materials, and the packing density. Dissipation of residues after sterilization is a function of the product- and packaging-related factors listed above plus the conditions in which the product is being held (aeration). 

In the long run, corrugated cardboard boxes and wooden pallets may allow residues to hang around the load and the product longer than necessary. Loads should not be left to aerate in conditions where ventilation may be restricted by too great packing densities or where some pallets may occlude air movement around others. 

First, let us consider the matters required for LiCoO. The specification of LiCoOj supplied by a certain company is shown in Table 2.4 as an example. Naturally, the most important property is the electrode density, which is related to the packing density and the density of the sheet electrode. These data are important for the battery manufacturers in order to stuff the cathode active material, such as LiCoOj, into the battery case with constant volume as much as possible. Currently, it seems that 96 wt% of the cathode mixture is LiCoO and the residual 4 wt% is the binder and the conductor, such as carbon. Thus, it is important to stuff electroactive LiCoOj even 1% more. The electrode density within the battery case is increased by the increase in both cathode sheet density and packing density, which leads to the improvement of cell capacity. 

With the increase in packing density of dynamic RAMs, soft errors caused by alpha particles are becoming an increasingly important cause of device malfunctioning. (For further information on soft errors see Section 10.3.) Alpha particles are emitted from uranium and thorium isotopes residual in most packaging materials and thin films of polyimides deposited upon a chip surface have been successfully evaluated as alpha particle barriers. Polyimides can be made pure enough to contain no detectable amounts of uranium or thorium and a 40 xm thick film may reduce the soft error generation rate by up to 1000 times. A typical example of a commercially available polyimide alpha particle barrier is DuPont s Pyralin PIH 61454. 

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