Ghadiri

Trost and Ghadiri have found a Lewis-acid-mediated intramolecular cyclization of allyl sulfones. When the allyl sulfone 40 is treated with AlClj, polycondensed aromatic system 41 can be obtained in good yield (equation 24). The mechanism probably involves... 

However, there is evidence that reactions of aluminium hydride produced in situ involve single-electron-transfer (SET) processesThe reactions described by Trost and Ghadiri have most likely not been studied in sufficient detail to permit an adequate description of the reaction mechanism to be given at this stage. It is, however, quite likely that the Grignard reactions catalyzed by copper(II) and nickel(II) complexes , as developed by julia - and by Masaki , do involve SET processes, although, if this is so, the preservation of stereochemistry in some of the examples described by these workers is quite remarkable. (In this context, the reader s attention is drawn to Reference 196, end of this section.)... 

Ghadiri MR, Granja JR,Milligan RA,McRee DE, Khazanovich N (1993) Nature 366 324... 

The scientific world was amazed to hear that David Lee, from the laboratory of Reza Ghadiri (Scripps Research Institute, La Jolla, California), had found a self-replicating peptide (Lee et al., 1996) there are analogies to the experiments with oligonucleotides (see Sect. 6.4). Lee was able to show that a certain peptide, containing 32 amino acids, can both function as a matrix and also support its own synthesis autocatalytically. The information transfer is clearly more complex than that involved in nucleic acid replication. In the case of this particular peptide, both the... 

Severin K, Lee DH, Martinez JA, Vieth M, Ghadiri MR (1998b) Angew Chem Int Ed 37 126... 

The minimal cell, as the simplest system which has all the required properties of life (metabolism, self-reproduction and the ability to evolve), is presently studied as part of a new research discipline synthetic biology. This includes subjects such as synthesis in branches of biological systems, for example, of new RNA species, new peptides and new nucleic acid analogues, as well as the synthesis of peptide nucleic acids. One example is the work of M. R. Ghadiri and G. von Kiedrowski on self-replication of oligonucleotides and oligopeptides (Luisi, 2006b). 

Leman, L., Orgel, L. and Ghadiri, M.R. (2004). Carbonyl sulfide - mediated prebiotic formation of... 

Ghadiri et al. (1992b, 1994, 1995) developed a more fundamental approach. They consider the particles entrained into the jet and relate the production of attrited fines to the attrition rates obtained from single particle impact tests (cf. Sec. 4.3). According to their model, it should be possible to predict jet attrition rates in fluidized beds on the basis of single particle impact tests combined with a detailed description of the jet hydrodynamics. 

The discrepancies between the exponents found by different authors are not astonishing considering the different methods of measurement and evaluation. For example, Ghadiri et al. (1992a) included the initial breakage in their calculation of the attrition rate, whereas Werther and Xi (1993) measured the attrition rate under steady state conditions (cf. Fig. 2). 

Again, as in the case of jet attrition, attention must be paid in the experimental determination of Ra bub to the isolation of the attrition that is due to bubbles. There are basically two ways to do this. The one is to use a porous plate distributor in order to avoid any grid jets. The other is the procedure suggested by Ghadiri et al. (1992a) which is depicted in Fig. 7 the measurement of the production rate of fines at different values of the static bed height permits to eliminate the grid jet effects. 

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