Two Distinct Stages

Pseudorabies virus apparently causes delayed, but not early, virion-associated shut-off. The inhibition of cellular protein synthesis by PRY is prevented by actinomycin (Ben-Porat et ah, 1971 Ihara et al., 1984). By labeling proteins during the hour immediately following reversal of a cycloheximide block it was shown that host pro- 

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A mechanism consistent with these facts is presented m Figure 19 7 The six steps are best viewed as a combination of two distinct stages Formation of a tetrahedral intermediate characterizes the first stage (steps 1-3) and dissociation of this tetra hedral intermediate characterizes the second (steps 4-6)... 

All these facts—the observation of second order kinetics nucleophilic attack at the carbonyl group and the involvement of a tetrahedral intermediate—are accommodated by the reaction mechanism shown m Figure 20 5 Like the acid catalyzed mechanism it has two distinct stages namely formation of the tetrahedral intermediate and its subsequent dissociation All the steps are reversible except the last one The equilibrium constant for proton abstraction from the carboxylic acid by hydroxide is so large that step 4 is for all intents and purposes irreversible and this makes the overall reaction irreversible... 

The RSST charts also point out another important difference between resoles and novolacs. Fig. 2 shows that resole reactions take place in two distinct stages with initiation temperatures at about 40-50°C and 100-140°C, respectively. 

A small number of pyrroles undergo addition of acetylenedi-carboxylic acid across the 2,5-positions yielding adducts similar to those obtained from cyclopentadiene. In the case of 1-benzylpyrrole and the acid, some (13) is formed, probably through the intermediary of a species such as (8) a strong case has been made for the supposition that the Diels-Alder reaction occurs in two distinct stages,... 

There are two distinct stages in viscosity change with the addition of NBR in the blend. First, there is a rapid rise of viscosity with the initial addition of NBR, then beyond 50% of NBR, viscosity increases slowly, except for the preheated blends where viscosity decreases marginally at the higher level of NBR. 

In these developments there were two distinct stages the first one, which dealt with the nearly linear oscillations, found its perfect algorithm in the theories of Poincare (both topological and analytical), which constitute the major part of this review here the discoveries were most striking as well as systematic. Numerous phenomena that had remained as riddles for many years, sometimes even for centuries, were systematically explained. We indicate in Part I of this chapter the qualitative aspect of this progress and in Part II, the quantitative one. 

The bottom-up approach contains two distinct stages. First, by successive backpropagation steps one builds a decision policy. Then, this uncovered policy is evaluated and refined, and its expected benefits confirmed before any implementation actually takes place. This two-stage process is conceptually similar to dynamic programming solution strategies, where first a decision policy is constructed by backward induction, and then one finds a realization of the process for the given policy, in order to check its expected performance (Bradley et al., 1977). 

The reduction of cyanopentaamminecobalt(III) by Cr in acidic perchlorate media proceeds in two distinct stages ... 

The main process of combustion of blackpowder was studied exhaustively by Nobel and Abel and by Berthelot. These experimental results were examined in much greater detail by Debus, who has provided a self-consistent account of the chemical reactions involved. Debus considers that the overall reaction can be divided into two distinct stages (a) a rapid oxidation process and (b) a slower reduction process. 

Incorporation of a 2% level of either ZnSn(OH) or ZnSnO into the resin, leads to marked differences in its thermal degradation profile. The initial decomposition comprises two distinct stages, the major step occurring at a lower temperature than that of the untreated polymer, which may be indicative of promotion of bromine volatilisation by the zinc stannates. Furthermore, the amount of residue burnt off in the char oxidation step is greatly increased in the tin-containing samples, and the temperature at which this process occurs is significantly higher than in the base resin. 

Allenes are reduced in two distinct stages. In the first stage, the major products are olefins, accompanied by a small amount of the alkane, while in the second stage the olefins produced are reduced to alkanes. The selectivity of reduction varies with the metal34, and for allene itself at various temperatures it decreased in the following series of metals ... 

These results are explained by extending the models of Kumar and Kuloor discussed earlier in Sections IV and V. At any orientation, the bubble is again considered to be formed in two distinct stages, but the conditions for the termination of the two stages are different in this case. 

In an early study in rats, subcutaneous injections of triphenyl phosphite caused two distinct stages of neurotoxic action. The early, rapidly developing stage was characterized by fine or coarse tremor, usually involving the large muscle groups. The tremor disappeared in surviving animals within a few hours. The... 

The Isometric ion plots of Figures A and 5 indicate that evolution of benzene from the silicone-epoxy samples occurs in two distinct stages, with the low temperature peak attributable to residual solvent species. Above 200°C, thermal degradation processes involving scission of the Si-phenyl bond occur and account for the increased formation rate of benzene. The other high temperature volatile products are similar to those observed for the novolac epoxy samples, and are attributed to decomposition of the epoxy fraction of samples D and E. 

In this work two distinct stages in the process were identified ... 

The proposed explanation for the formation of the fractal-type gel network shown in Figure 7.11 involves two distinct stages (Firoozmand et al., 2007), as indicated below. 

When 0,(y-diazidoazobenzene (10) is heated, nitrogen is liberated in two distinct stages one mole at the surprisingly low temperature of 58° yielding 2-(o-azidophenyl>2H-benzo-triazole (11) and the second mole at approximately 17Gl0 to give dibenzo-1,3a,4,6a-tetraazapentalene (12).1H 1M It seems quite reasonable that 11 is formed by a concerted process and 12 by a nitrene intermediate. 

Secondary Processes. Snelling et al. (917) followed the consumption of 03 as a function of time after flash photolysis of 03. The results show that the ozone consumption occurs in two distinct stages, a very fast process (less than 50 fisec) followed by a slow process lasting many milliseconds. The fast process is attributed to the reaction... 

Sequential Processes. In many cases (anhydride cured-epoxies, amine-cured epoxies, etc.), thermal degradation curves, for instance gravimetric ones, exhibit two distinct stages (Lehuy et al., 1991). The first one corresponds to a relatively fast, pseudo-first-order process, whereas the sec-... 

Figure 9.22 DTA-TGA trace for Ni(NCS)2(4-Phpy)4 4C6H6 showing the endothemic loss first of benzene and then the 4-phenylpyridine ligands in two distinct stages. (Reprinted with permission from IUCr).

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