Secondary cycle

This list is by no means exhaustive. Many other amines have been employed from time to time, and novel materials are occasionally tested under high temperature conditions to control problems specific to critical units, especially in PWR secondary cycles and other power applications. 

In this case, the crosslinking density is the sum of the effective crosslinking density and the secondary cyclization, since both crosslinkages are elastically effective. The calculation conditions are the same as Figure 1 except that the number of secondary cycles formed per effective crosslinkage T) is 20. 

The catalytic cycle is shown on page 539 (the secondary cycle is shut off by maintaining a low concentration of olefin) ... 

When characterizing polymer networks, the following definitions are typically applied [150] and are illustrated in Fig. 7. When a radical on a polymer chain propagates through a pendant double (i.e. a double bond from a monomer with one double bond already reacted), a crosslink, secondary cycle, or primary cycle can be formed. A crosslink forms when the radical reacts with a pendant... 

Fig. 10. Kinetic gelation model prediction of the relative fraction of crosslinks, primary cycles, and secondary cycles as a function of double bond conversion for the polymerization of a multifunctional monomer...

When the secondary reaction cycle shown in Scheme 6D.3 was discovered, it became clear that an increase in the rate of hydrolysis of trioxogly colate 10 should reduce the role played by this cycle. The addition of nucleophiles such as acetate (tetraethylammonium acetate is used) to osmylations is known to facilitate hydrolysis of osmate esters. Addition of acetate ion to catalytic ADs by using NMO as cooxidant was found to improve the enantiomeric purity for some diols, presumably as a result of accelerated osmate ester hydrolysis [16]. The subsequent change to potassium ferricyanide as cooxidant appears to result in nearly complete avoidance of the secondary cycle (see Section 4.4.2.2.), but the turnover rate of the new catalytic cycle may still depend on the rate of hydrolysis of the osmate ester 9. The addition of a sulfonamide (usually methanesulfonamide) has been found to enhance the rate of hydrolysis for osmate esters derived from 1,2-disubstituted and trisubstituted olefins [29]. However, for reasons that are not yet understood, addition of a sulfon-amide to the catalytic AD of terminal olefins (i.e., monosubstituted and 1,1-disubstituted olefins) actually slows the overall rate of the reaction. Therefore, when called for, the sulfonamide is added to the reaction at the rate of one equivalent per equivalent of olefin. This enhancement in rate of osmate hydrolysis allows most sluggish dihydroxylation reactions to be mn at 0°C rather than at room temperature [29]. 

Moreover, the secondary cycle was utilized to develop a new procedure for racemic osmium-catalyzed dihydroxylation. Dihydroxylation with citric acid as... 

In peaceful uses of nuclear reactions, electrical power plants can be driven by a nuclear reactor very close to criticality, with careful control of neutron flux excess heat from the well-shielded nuclear reactor is driven off by a liquid (H20, Na, or Hg), which in a secondary cycle or a tertiary cycle generates electricity by turning induction turbines. 

Figure 1 (a) The primary and secondary cycles (b) the water-based phosphate cycle (c) the land-based phosphate cycle (Reproduced by permission of The Royal Society of Chemistry)... 

Synthesis of Camphor.— The relationship of camphor to pinene, the terpene present in turpentine, is of especial interest and importance in connection with its synthesis. Pinene is the unsaturated di-cyclic terpene related to the saturated di-cyclic terpene pinane (p. 823). In both of these terpenes the di-cyclic arrangement is different from that in camphane and Bornylene in that the isopropyl group in forming the secondary cycle joins the meta carbons instead of the para. Now pinene, by addition of hydrogen chloride, forms a hydrochloride which has been referred to as artificial camphor. This hydrochloride is identical with the hydrochloric acid ester of Bomeol and may be converted into Bomeol by hydrolysis. Now as Bomeol can be oxidized to camphor we may thus obtain true synthetic camphor from pinene. The reactions, involving an intermediate product and then rearrangement of the secondary cycle in pinene, are as follows ... 

Infected plant parts may themselves become a source for further infection. These secondary cycles, as they are called, often are important in intensifying the disease. Purposely destroying diseased plants or those suspected of harboring disease is a way to keep disease from spreading to healthy plants. 

Using the potassium ferricyanide cooxidant system, the non-enantioselective secondary cycle appears to have been suppressed, consequently higher enantiomeric excesses are obtained. The mechanism for the catalytic process is outhned... 

Thomas, M.B., Wood, S.N. and Lomer, C.J. (1995) Biological control of locusts and grasshoppers using a fungal pathogen the importance of secondary cycling. Proceedings of the Royal Society, London, B, 259, 265-270. 

Thus, the efficiency of the NOx catalyzed destruction of odd oxygen depends on the competition between photolysis and reaction with atomic oxygen for the NO2 radical the rate-limiting step for the destruction of odd oxygen is therefore provided by the NO2 + O reaction. Other secondary cycles should also be noted ... 

P-elimination occurs and formation of the Pd—H bond results in loss of CP. This is followed by attack by CP with H atom migration to give a cr-bonded CH(OH)CH3 group. Elimination of CH3CHO, H and CP with reduction of Pd(II) to Pd(0) occurs in the last step. To keep the cycle going, Pd(0) is now oxidized by Cu (equation 26.3). The secondary cycle in Figure 26.2 shows the reduction of Cu to Cu+ and reoxidation of the latter by O2 in the presence of (equation 26.4). 

Figure 9.4 Different types of crosslinkages (a) intermolecular, (b) intramolecular, yielding a primary cycle, and (c) intramolecular, yielding a secondary cycle.

In oilfields, after the primary and secondary cycles of oil recovery, chemicals may be injected to drive out additional oil in an enhanced oil recovery process, which may involve creating in situ emulsions in the reservoir. Figure 7 shows a reservoir schematic with such a chemical flood. 

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