Concurrency electronic systems

There was no indication during the inspection that the XXXX system [and associated electronic records and signatures] was being validated. In fact there was no evidence that a concurrent manual system was in place. [FDA Warning Letter, 2001]... 

The SN(AE) p,° reactions at C-3 usually proceed very smoothly since the C-3 carbon is very susceptible to a nucleophilic attack and elimination of the nucleofugic substituent from the C-3 adduct allows the triazine ring to gain its 6-rr-electron system. In some cases, however, the concurrent addition at C-5 occurs, resulting in a lower yield of the SN(AE),ps" product at C-3 or causing transformations of the ring (Scheme 35) (see also Section VI). 

The primary radical attacks the vinyl group in the monomer first and then the free electron is transferred from this group to the central metal ion. This process is facilitated by the presence of a conjugated chain (a long coplanar 7t-electronic system). Chain propagation does not start until after the complete reduction of Cu(ll) to Cu(l). A concurrent stage consists of P-elimination of a... 

The interpretation of MCD spectra requires a close interaction with theory. So far, this has been nearly exclusively semiempirical theory, but the time appears ripe for ab initio calculations, at least for the smaller among r-electron systems, including not only purely electronic but also vibronic effects. Concurrently, high-resolution spectra will need to be measured for many of the molecules for which only low-resolution spectra are available today. A qualitatively higher level of understanding of electronically excited states of n systems can be expected to emerge from this combination. 

An electronic system is a concurrent parallel system. All circuits in an electronic assembly are continuously operating. In contrast, software systems incorporate the notion of program flow, in which the sequence of instructions executed is explidtly stated through features such as loops and conditional statements. 

Several proposals have been made to fit the borderline reactions into a well-defined mechanistic scheme. Most of these adopt one of two viewpoints either (1) borderline substrates undergo concurrent SnI and Sn2 processes, with the particular system determining which mechanism, if either, predominates or (2) all Sn reactions are related by essentially the same mechanism, which differs from case to case in the detailed disposition of electrons in the transition state. In this view pure SnI and Sn2 processes are merely the extreme limiting forms of a single mechanism, and the borderline mechanism is a merged process having some features of both. 

LDMS is particularly well suited for the analysis of porphyrins.35-39 The heme molecule—a 22 rc-electron conjugated protoporphyrin system (Figure 8.1)—is an efficient photo-absorber in the visible and near UV (with an absorption maximum—the Soret band—near 400nm). This feature, concurrently with its low ionization potential, warrants that direct LDMS will possess extremely low limits for heme detection. The uses of IR or UV LDMS for structural characterization of natural porphyrins and their metabolites, synthetic monomeric porphyrins (e.g., used in photodynamic therapy), porphyrin polymers, and multimeric arrays, have been well documented.41148 In addition fast atom bombardment MS has been used to characterize purified hemozoin, isolated from the spleens and livers of Plasmodium yoelii infected mice.49... 

Formulas of Ionic Compounds As we mentioned earlier, compounds (like atoms) must be electrically neutral. The net charge on an ionic compound must be zero. When a metal gives its electrons away to form a cation, there has to be some other species, often a nonmetal, present to accept the electrons. Thus, whenever a cation is forming, there is also a concurrent formation of an anion. Chemical systems have to remain electrically neutral. 

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