Fragmentation model

One of the more challenging things to understand in these multiple-fragment models is the evolution of the present-day surviving thin old disk, particularly since a recent accretion of the thick disk could destroy the thin disk. Further, in these models stars should not form in a thin disk at all until after most of the merging is complete, since otherwise disks have too small a scale-length (Navarro Steinmetz 1997). A solution to both these issues may be that the local old thin disk is also accreted in these models. Here the recent results of many authors (cf... 

Brush-heap model, see Random-fragmentation model... 

Ramsey theory, 22 201-204 Random-fragmentation model, Szilard-Chalmers reaction and, 1 270 Random-walk process, correlated pair recombination, post-recoil annealing effects and, 1 288-290 Rare-earth carbides, neutron diffraction studies on, 8 234-236 Rare-earth ions energy transfer, 35 383 hydration shell, 34 212-213 Rare gases... 

Rorije, E., Peijnenburg, W.J. and Klopman, G. (1998) Structural requirements for anaerobic biodegradation of organic chemicals a fragment model analysis. Environ. Toxicol. Chem., 17 (10), 1943-1950. 

Figure 24. Fragmentation model for computing contributions of different fragmentation channels to the observed signal intensities.

Approximate Conformation Optimization from Fragment Models... 

Hydrocarbon Fragments - Modeling by Molecular Orbital and Cluster Chemistry. A basic guideline for metal surface coordination chemistry with respect to hydrocarbon or hydrocarbon derivatives may be formulated as follows If the stereochemistry of the chemisorption state allows C-H hydrogen atoms to closely approach surface metal atoms then the chemisorption state should be further stabilized by the formation of a three-center two-electron C-H-metal bond. This effect should be more pronounced the more electron deficient the metal surface. There should be an activation of the C-H bond and the hydrogen atom should become more protonic in character. If the C-H bond is sufficiently weakened by this interaction then C-H bond cleavage should result. 

Two alternative mechanisms of ATP hydrolysis that appear both steri-cally and chemically reasonable can be suggested. The first possibility would be a direct in-line attack by a H2O molecule on the y-phosphate of ATP, with Asp-206 acting as a proton acceptor. The plausibility of this alternative was initially suggested by the comparison of the actin and HSC70 ATPase fragment structures, and more specifically by superposition of a CaATP nucleotide, with the conformation observed in actin, on the ATPase fragment model (Flaherty et ai, 1991). An HgO molecule appears to intercalate between the carboxyl of Asp-206 and the hypothet-... 

Alexander S. G. and Agnor C. B. (1998) N-body simulations of late stage planetary formation with a simple fragmentation model. Icarus 132, 113-124. 

The hot-zone model differs from the random-fragmentation model in an important respect. The random-fragmentation model is based upon free radical recombinations. The authors model suggests that in view of the relatively low concentration of free radicals present in the hot zone, chemical reactions with the parent species may also play an important part. The picture may be further complicated by ion-molecule reactions (71). 

D.L. Tabb, A. Saraf, J.R. Yates, III, GutenTag High-throughput sequence tagging via an empirically derived fragmentation model. Anal. Chem., 75 (2003) 6415. 

Some fairly hindered catalysts, such as the rosindones [97] and metal porphyrins [98] are as efficient as AQ at low concentrations in delignifying wood and/or fragmenting models. This observation is contrary to what one would expect with an adduct mechanism metal ion complexes have been proposed to fragment lignin models by SET pathways. Moreover, carbohydrates have been shown to facilitate p-ether cleavage in lignin models [99] and can also transfer electrons to QMs [87]. 

Chen W, Gordon MS. The effective fragment model for solvation internal rotation in formamide. J Chem Phys 1996 105 11081-11090. 

B. Liu and A. D. McLean, ]. Chem. Phys., 91, 2348 (1989). The Interacting Correlated Fragments Model for Weak Interactions, Basis Set Superposition Error, and the Helium Dimer Potential. 

Table 3. Values of parameters used in fragmentation model and predicted range of particle sizes...

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