A triplex

The single-action pump is usually available with three, five and even seven pistons. The odd number of pistons allows the pump to be rotationally balanced, and the use of at least three pistons reduces the discharge pulsation of these single-acting pumps. A three piston pump single-action pump is called a triplex pump. A five piston, or seven piston single-acting pump is called a multiplex pump. 

Mud pumps consume more than 60% of all the horsepower used in rotary drilling. Mud pumps are used to circulate drilling fluid through the mud circulation system while drilling. A pump with two fluid cylinders, as shown in Figure 4-99, is called a duplex pump. A three-fluid-cylinder pump, as shown in Figure 4-100, is called a triplex pump. Duplex pumps are usually double action, and triplex pumps are usually single action. 

Fig. 9 Hole transport dynamics and structures for hairpins possessing GTGG and crossstrand GACC hole transport sequences, a triplex hole transport system, and a two-step hole transport system...

Alternative 2 consists of preliminary treatment followed by dual-media pressure filtration, and two-stage air stripping (Figure 8.4). The preliminary treatment step for iron removal would be exactly the same as specified under Alternative 1. The filters would be recommended to remove suspended matter and particulate iron prior to the air strippers. The required filtration capacity could be provided with either a duplex system of two 60-in.-diameter filters or a triplex system of three 42-in-diameter filters. 

Yoon and Chae28 have described the DCA-induced photochemical conversion of the cyclopentadiene derivatives 63 into several products. However, only the awri-Bredt adduct 64 is different from those obtained by thermal activation. The experimental data collected have implicated a triplex intermediate 65 in the formation of 64. This triplex is the result of interaction between the diene, the non-conjugated alkene component and the sensitizer. While a mixture of cyclopentadienes was used, it is likely that the products 64 are formed exclusively from the 2-isomer 66. 

Peptide nucleic acids (PNAs with a peptide like backbone) also bind via the major groove (Neilsen, 1999). PNAs form a triplex (Lohse et al, 1999), which then result in the displacement of the non-complementary oligopyrimidine DNA strand. This has been extensively reviewed by Hurley (2002). 

The proposed mechanism for exciplex quenching involves formation of a triplex l(t-lT(R3N)2 ) in which the amine dimer cation radical (62) has formed a 3-electron a bond. 

We will discuss briefly the reactive species such as an exciplex and radical ion species generated by the excitation of organic molecules in the electron-donor (D)-acceptor (A) system. An exciplex is produced usually in nonpolar solvents by an interaction of an electronically excited molecule D (or A ) with a ground-state molecule A (or D). It is often postulated as an important intermediate in the photocycloaddition between D and A. In the case of D = A, an excimer is formed as an excited reactive species to cause photodimerization. In some cases, a ter-molecular interaction of an exciplex with another D or A generates a triplex, which is also a reactive intermediate for photocycloaddition. The evidence for the formation of excimers, exciplexes, and triplexes are shown in the fluorescence quenching. Excimer and exciplex emission is, in some cases, observed and an emission of triplex rarely appears. 

Enantioselective triplex Diels-AIder reaction. 1,3-Cyclohexadiene is known to undergo Diels-AIder reactions with electron-rich dienes when irradiated with arene sensitizers. The reaction is presumed to involve a triplex involving the sensitizer (15, 129). The first enantioselective example of this Diels-AIder reaction has been achieved using (-)-l as sensitizer. Thus irradiation of 1,3-cyclohexadiene with trans-P-methylstyrene in the presence of (-)-l at -65° provides the endo-adduct 2 in 15% ee (equation I). The enantioselectivity decreases with an increase of the temperature, being 1% at 25°. 

Dorr, Lewis, and co-workers found evidence through quenching experiments and flash spectroscopy for a triplex in the system trans-stilbene — amine — benzene — [105]. They quenched singlet excited trans-stilbene with various mono- and diamines and found a steric effect on the quenching constant The a, co-diamines (dabco, diaminoethane, -propane and -butane) quenched the stilbene fluorescence more efficiently than the monoamines, depending on the chain length between the amino groups. This was ascribed to the formation of cyclic radical cations, with a N-N three electron a-bond. In this case, an exciplex between diamine and stilbene is formed. 

Whether the role of the second olefinic partner is catalytic or a triplex intermediate is involved is not yet clear. The role of triplexes in photoreactions of aromatic compounds with olefins may be even more complex. For example, excited biphenyl forms both a fluorescent dual and triple exciplex with 2,3-dimethyl-2-butene [120]. The possibility of these two pathways of deactivation can explain the inefficient photocycloaddition in the particular case of 1biphenyl /cyclopentene [121]. 

In 1983, Jones et al. [104] reported on the photosensitized [4 + 2]-cyclodimeriza-tion of 1,3-cyclohexadiene. They found evidence for a tight complex as an intermediate of the Diels-Alder adducts rather than free radical cations. These findings extended an earlier work of Libman [109] but, however, left a decision open pro or against a triplex intermediate. In a series of papers, Schuster and coworkers elegantly extended these preliminary discoveries to its generalization as the Triplex-Diels-Alder Reaction . 

A triplex has been proposed as an intermediate in some photoreactions. Yang and co-workers [54] found that addition of 1,3-dienes to anthracene excimers leads to different products than does its adition to monomeric excited arenes. Lewis and co-workers [55, 56] found that stilbene excimers can be intercepted by dimethyl fumarate to give an oxetane through a presumed triplex. More recently, Schuster and co-workers [57,58] studied the Triplex Diels-Alder reaction of 1,3-dienes with enol, alkene, and acetylenic dienophiles. Take 9,10-dicyanonaphthalene (DCN)/indene (IN)/l,3-cyclohexadiene (CHD) system as an example ... 

The lower-right panel of figure 6.3 presents data on the effects of NaCl on activity of MDH from pig heart and two vascular plants that differ in salt tolerance (Greenway and Osmond, 1972). Despite NaCl not being a physiologically appropriate salt to use to examine salt effects, these results do illustrate some important points. First, as shown by the comparison of A triplex spongiosa (salt tolerant) and... 

Figure 1 shows a triplex plunger pump and its flow pulsation at a volumetric efficiency of 95 %. The volumetric efficiency, representing the ratio of the actual volume flow Q to the theoretical flow (equation (1)), depends essentially on the fluid and working chamber elasticity... 

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