Impurity grid

The impurity grid acts as a hypothetical model to define what could potentially form during the drug substance synthesis. Since any material from this grid which actually forms will be a PRI or in the mother liquors, these are the least important component of the KPSS. If any of the impurity grid substances are included in the KPSS, they may need to be synthesized. 

Process-Related Impurities (PRIs) e Isolated components Raw materials Isolated ntermediates Mother Liquors Un-recrystallized bulk lots Pur. Deg. or Stability samples Phase Equilibrium Supernatants Isolated Fractions Synthesis - Imouritv Grid... 

First the presence of barium and oxygen in the film was checked by X-ray analysis and electron energy loss spectroscopy respectively. It was taken as a signature of the ionomer films which were found to cover the whole grid. Silicon also appeared as a trace Impurity of unknown origin. 

The detailed interactions between the SiH radicals and silicon surfaces can be captured by MD simulations of radical impingement at a grid of locations on the surface with varying radical molecular orientation with respect to the surface. Tlie reactions of SiH with the pristine Si(001)-(2 x 1) surface can be classified broadly into two classes (Ramahngam et al., 1998b). The radical either adsorbs dissociatively onto the surface or penetrates below the top surface layer into the substrate also resulting in dissociation. The H atom that is released upon radical dissociation becomes an interstitial impurity of the substrate Si lattice and it can migrate rapidly or channel deeper into the substrate. These reactions can be represented as... 

This chapter reviews the effects of additives in the positive active-material of the lead acid battery. Common materials found in the oxide and the positive-plate paste, such as lead oxides, basie lead sulfates, and lead earbonate, are not included. Additives and impurities that derive from grid eorrosion or from the reaction of the plate with the electrolyte are also beyond the seope of this chapter. 

As positive grid corrosion is an important influence on the expected lifetime of standby batteries, there have been many investigations of the parameters that influence the corrosion rate. It has been established that many parameters influence grid corrosion and growth. The most important are (i) alloy composition (ii) grid design (iii) casting conditions (iv) positive active material (v) impurities that accelerate corrosion (vi) battery temperature and (vii) potential of the positive plate. 

Flooded batteries operated in RAPS systems require water maintenance on a regular basis. Unfortunately, it is not uncommon for owner/operators to neglect this tedious task. This situation can affect the performance of the system and can ultimately result in premature failure of the batteries. Problems can also arise if the water used for topping up contains excessive amounts of impurities. For example, the presence of chloride ion leads to enhanced corrosion of the positive grids [11]. Also, some RAPS systems are located in areas where access is very difficult, e.g., microwave repeater stations on the tops of mountains. Hence, the cost of maintaining flooded batteries can be very high. 

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