Compositional alternative explanation

Alternative explanations of the high conductivity of composite materials obtained by polymerization filling are given in works [62, 63] where conductivity higher than that of the graphite proper is attributed to a polymer interlayer between graphite particles, are, in our opinion, insufficiently convincing and cannot explain the whole of the experimental data. 

Philosophers of antiquity had offered composition and structure as alternative explanations for chemical behavior. These were thought to be exclusive views, but they became one when joined by Daltons inspired conception of a quantized atomic weight. By permanently solving the problem of composition, Daltons theory also made possible the open-ended exploitation of molecular structure, the central theme of organic chemistry. 

The alternative explanation for the phenomenon is that bacterial communities respond physiologically to changes in DOM inputs rather than by replacing populations. Bacteria obviously have some capacity to physiologically adapt, but their reservoir of genetic information is limited, and fundamental parameters such as uptake rates and substrate affinities are determined by cell size and enzyme structure, which may be difficult to modulate. Microcosm studies suggest that changes in productivity and enzyme kinetics measured 24-48 h after DOM amendment are associated with displacements in community composition as measured by DNA comparison techniques (see Chapter 14). 

The depletion in FeO may be understood in at least two ways. First, the crystalline grains may be equilibrium condensates from a hot solar nebular composition gas with iron sequestered to metals or sulfides (see e.g. Chapter 4). In this case the condensed grains either had to condense slowly to form crystal domains, or had been reheated and thermally annealed at a later epoch. The second, alternative explanation is that ferromagnesian amorphous silicate grains were thermally annealed in a reducing environment, e.g. in the presence of carbon. Heating such precursors leads to the formation of metallic spheroids embedded between the forsterite crystals, as the initial FeO component is reduced (see e.g. Fig. 8.3 and Connolly et al. 1994 Jones Danielson 1997 Leroux et al. 2003 Davoisne et al. 2006). Because carbon is ubiquitously present in primitive Solar System materials, this pathway offers a natural explanation to the observed FeO-poor silicate crystals. It is yet to be determined whether low-temperature crystallization processes, discussed in Section 8.1.1, would also lead to FeO depletion. 

ESMS has been used to characterize the intermediate Nin-complexes formed in the coupling reaction of 2-bromo-6-methylpyridine in the presence of Raney nickel (Scheme 1) [45]. The composition of the intermediate had already been determined previously by elemental analysis, but the ES mass spectra, showing a strong peak for the ion [Ni2(dmbp)2Br3]+, pointed to a dimeric structure. It was concluded that this ion was formed by the loss of Br from the dimeric structure 1. An alternative explanation is that the intermediate has the more common four-coordinate structure 2, and that the observed peak was due to the ion-paired species [Ni2(dmbp)2Br2]2++Br. The dimeric nature of the intermediate was confirmed by a cross experiment when mixtures of differently substituted pyridines were reacted, mixed ligand dinickel species were observed in the ES mass spectra. 

Alternative Explanations for the Isotopic Composition of Precambrian Chert... 

MCM-1 sample No.34 synthesized with Pr4N-OH shows hydroxyl vibrations at 3740 cm 1 and 3670 cm 1. The chemical composition given in Table IV suggests that isomorphous substitution according to mechanism 2 does not occur in this material. If the 3670 cm 1 band represents Al-OH-Si groups, there should be a contribution of mechanism 2 and the P content should be lower than 50%. An alternative explanation is that the 3670 cm 1 band in this sample represents P-OH groups, associated with the excess of P in the sample. 

This indicates that for any feed composition, the copolymer formed will have an equimolar regularly alternating composition. The chemistry behind these systems has been extensively discussed in the literature, and the charge-transfer complex concept was for a long time the prevailing theory to explain this behavior [73-75]. More recently, Hall and Padias [76, 77] have proposed an alternate explanation based on polar effects when an electron-donor and an electron-acceptor monomer interact. This last theory has the additional virtue of explaining the fact that many... 

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