PCP system

Theoretical studies of catalytic alkane-dehydrogenation reactions by [(PCP )IrH2], PCP rf-C6H3(CH2P112)2-l, 3 and [cpIr(PH3)(H)]+, suggest that they proceed through similar steps in both cases namely (i) alkane oxidation, (ii) dihydride reductive elimination, (iii) /3-II transfer from alkyl ligand to metal, (iv) elimination of olefin.402 The calculated barriers to steps (i), (ii), and (iv) are more balanced for the PCP system than for cp(PH3). 

Pincer complexes catalyze a variety of other organic reactions [49-51]. Hence, this work is currently being extended to other metals, and other more readily accessible PCP systems. For example, as shown in Scheme 3, lO-Rfs can be converted to the iridium hydride chloride complex 15-Rfs. Closely related dihydride complexes catalyze dehydrogenations of alkanes at high temperatures [52], However, no efforts to develop recoverable catalysts have been reported to date. 

This is markedly higher than the TONs typically observed for phosphine-based Ir—PCP systems (ca. 250 under identical conditions). Electron-withdrawing substituents such as C5F5 (5e) and 3,5-(CF3)2-C6H3 (5f) considerably improve the catalytic activity (Table 12.1). Notably, the MeO-substituted Ir—PCP complex 5c seems to operate differently, and remains active over a longer time range than the other phosphinite complexes, thus reaching final TONs that are comparable to those of 5f. 

The result of theoretical investigations have suggested that cleavage of a B—H bond occurs to initiate ammonia borane dehydrogenation [38]. Alternatively, the oxidative N—H addition of ammonia to the dehydrogenated intermediate C may constitute a feasible reaction pathway due, in particular, to the fact that ammonia and aniline oxidative addition to la and related iridium-PCP systems has been reported experimentally [39]. 

In passing, it may be of interest to point out that in 2004, the New York state government sponsored a study to determine the technical and economic feasibility of using large PCP systems for underground freight transport in New York City. The study found that all of the six applications investigated are technically feasible, and five of them are also cost-effective. 

York, K. Predicting the Performance of a PCP System Using a Linear Induction Motor for Capsule Propulsion M.S. Thesis, Department of Civil Engineering. University of Missouri-Columbia Columbia, MO, 1999. 

The same cycle is followed during the reactions of linear alkanes to form linear alk-enes. Although the thermod)mamics for dehydrogenation of cyclooctene are more favorable than those for the dehydrogenation of linear alkanes, primary C-H bonds typically undergo oxidative addition faster than secondary C-H bonds, as discussed in Chapter 6. Thus, linear alkanes react faster than cyclic alkanes. However, the accumulation of a-olefin inhibits the catalytic process. An T) -olefin complex formed from the a-olefin becomes the resting state of the catalytic cycle for reactions catalyzed by the POCOP system, instead of the vinyl hydride complex that is the resting state of the PCP system. The accumulation of the olefin complex that lies off the cycle leads to a lower concentration of the iridium complexes within the cycle and slower reactions as the concentration of a-olefin product increases. 

This paper presents a review of development in the pneumatic capsule pipeline (PCP) system and its potential future developments. Two commercial PCP systems have been installed in Japan. One is to transport 2 million tons of limestone annually from the mine to the cement works. It has been in operation since 1983 without environmental pollution, with its availability being as high as 94 - 98 %. The other was commissioned for tunneling of Japan s bullet train from 1991 to 1994. This application is an epoch-making tunneling project with cleanliness and safety. Sumitomo Metal Industries, Ltd. (SMI) is also studying the application of the PCP system to municipal solid wastes, parcels, etc. It is anticipated that the 21st century will see widespread uses of the PCP system by virtue of its effectiveness without enviroiunental impacts. 

The PCP system has a long history from the point of feasibility study and engineering-design, since its invention in the 19th century, however its use for commercial operations is very limited. Recent industrial concerns and trends such as environmental issues have enhanced the attention of the PCP system due to its environmental friendliness and its effectively diversified applications. This paper firstly traces SMI s experiences and operational scheme, as well as SMI s recent potential application, then explains the future technological developments in Japan. 

Up to now two commercial PCP systems have been installed in Japan. One is to transport limestone from the mine to the cement works and the other is to transport excavated earth from the excavating machine to the disposal area and ready mixed concrete in return. 

The outline of the PCP System is shown in Fig. 3. This system transports 100 cubic meter of excavated earth and 40 cubic meters of ready-mixed concrete every hour by launching capsule trains every 150 seconds[2]. The following shows the six components which compose this whole system ... 

Pneumogstis carini pneumonia (PCP), the most common of the opportunistic infections, occurs in more than 80% of AIDS patients (13). Toxoplasmosis, a proto2oan infection of the central nervous system, is activated in AIDS patients when the 004 count drops and severe impairment of ceU-mediated immunity occurs. Typically, patients have a mass lesion(s) in the brain. These mass lesions usually respond well to therapy and can disappear completely. Fungal infections, such as CTyptococcalmeningitis, are extremely common in AIDS patients, and Histop/asma capsulatum appears when ceU-mediated immunity has been destroyed by the HIV vims, leading to widespread infection of the lungs, Hver, spleen, lymph nodes, and bone marrow. AIDS patients are particularly susceptible to bacteremia caused by nontyphoidal strains of Salmonella. Bacteremia may be cleared by using antibiotic therapy. 

Harano and colleagues [48] found that the reactivity of the Diels-Alder reaction of cyclopentadienones with unactivated olefins is enhanced in phenolic solvents. Scheme 6.28 gives some examples of the cycloadditions of 2,5-bis-(methoxycar-bonyl)-3,4-diphenylcyclopentadienone 45 with styrene and cyclohexene in p-chlorophenol (PCP). Notice the result of the cycloaddition of cyclohexene which is known to be a very unreactive dienophile in PCP at 80 °C the reaction works, while no Diels-Alder adduct was obtained in benzene. PCP also favors the decarbonylation of the adduct, generating a new conjugated dienic system, and therefore a subsequent Diels-Alder reaction is possible. Thus, the thermolysis at 170 °C for 10 h of Diels-Alder adduct 47, which comes from the cycloaddition of 45 with 1,5-octadiene 46 (Scheme 6.29), gives the multiple Diels-Alder adduct 49 via decarbonylated adduct 48. In PCP, the reaction occurs at a temperature about 50 °C lower than when performed without solvent, and product 49 is obtained by a one-pot procedure in good yield. 

PCP is commonly used as a wood preservative having both antifungal and insecticide properties. It has also been used in a range of areas for antifungal, antibacterial, general herbicide, and slime prevention in both industrial and consumer applications. Chronic exposure to PCP has effects on the liver, kidneys, and immune system. PCP also has the potential to cause reproductive problems and has been listed as a probable carcinogen. 

The binding of PCP to its receptor initiates a series of coupled neurochemical events eventually leading to the expression of behavior. One such coupling reaction was described by BLAUSTEIN as a blockade of transmembrane channels that transport K+ into the neuronal cells. Since K+ movements are part of the process of neurotransmission between neurons, this effect of PCP may explain the results of studies by MARWAH and by JOHNSON, in which several neurotransmitter systems were shown to be involved in the actions... 

Figure 2 shows the elution profiles of several neuropeptides and the PCP-like material. When the PCP-active fractions were rechromatographed over a flatter gradient and in a different solvent system, it was clear that bombesin- and substance P-immunoreactiv-ity no longer coeluted with the PCP-like material. 

This laboratory, as well as others, has shown unequivocally that PCP affects a variety of parameters related to neurotransmission in several neuronal systems. This paper has focused on evidence for the involvement of dopaminergic, cholinergic, and glutama-tergic pathways, and evidence of their interactions in the rat striatum. However, the effects of PCP undoubtedly involve other neuronal systems in other brain areas. Thus, it must be borne in mind that the data discussed in this paper cannot possibly account for the more complex behavioral effects of PCP. 

French, E. Vantini, G. Contrera s, P. Pi 11 a pi 1, C. and Quirion, R. Phencyclidine (PCP) binding in the nucleus accumbens and PCP-induced hyperactivity are decreased following 60HDA lesions of the mesolimbic dopamine system. Neurosci Abst 10 1205, 1984. 

In rodents, PCP produces not only ataxia, but also stereotyped behavior and hyperactivity. The PCP-induced stereotyped behavior is thought to be due to changes in serotonergic and dopaminergic systems (Nabeshima et al. 1983 Martin et al. 1979 Sturgeon et al. 1981). It is not known whether PCP receptors mediate PCP-induced hyperactivity or stereotyped behavior or even the effect on neurotransmitter systems. It is also possible that mu, kappa, or sigma opioid receptors are involved (Castellani et al. 1982). 

The area under the PCP concentration-time curve (AUC) from the time of antibody administration to the last measured concentration (Cn) was determined by the trapezoidal rule. The remaining area from Cn to time infinity was calculated by dividing Cn by the terminal elimination rate constant. By using dose, AUC, and the terminal elimination rate constant, we were able to calculate the terminal elimination half-life, systemic clearance, and the volume of distribution. Renal clearance was determined from the total amount of PCP appearing in the urine, divided by AUC. Unbound clearances were calculated based on unbound concentrations of PCP. The control values are from studies performed in our laboratory on dogs administered similar radioactive doses (i.e., 2.4 to 6.5 pg of PCP) (Woodworth et al., in press). Only one of the dogs (dog C) was used in both studies. 

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