Core formation concomitant

Eventually, models that involved successive changes in accretion and core formation replaced these. How volatiles played into this was not explained except that changes in oxidation state were incorporated. An advanced example of such a model is that presented by Newsom (1990). He envisaged the history of accretion as involving stages that included concomitant core formation stages (discussed under core formation). 

Exponentially Decreasing Accretion with Concomitant Core Formation... 

For bodies the size of Earth, core formation did not occur as one single event but took place continuously during planetary growth. To determine realistic core formation ages for bodies like the Earth the W isotope evolution during continuous core formation must be considered (8, 35-38). During protracted accretion with concomitant core formation, the ratio of Earth s mantle... 

Figure 8.20 Structure and phase sequence of prototypical bent-core mesogen NOBOW (8) are given, along with space-filling model showing one of many conformational minima obtained using MOPAC with AMI force field. With observation by Tokyo Tech group of polar EO switching for B2 smectic phases formed by mesogens of this type, banana LC field was bom. Achiral, polar C2v layer structure, with formation of macroscopic spontaneous helix in polarization field (and concomitant chiral symmetry breaking), was proposed to account for observed EO behavior.

P13-like contact between P9.1 and P2.1. The molecule further compacts in the presence of200 mM Na+ ions, with a concomitant formation of more native tertiary contacts and reorganization of the PI 3 contact to its native form. Finally, only divalent ions (10 mM Mg2-1-) drive the formation of all the native tertiary contacts within the catalytic core of the ribozyme, thereby generating its fully compact form ( 45 A). [Reprinted from Uchida et al. (2003), Copyright (2003), with permission from Elsevier.]... 

Scheme 6.7. Concomitant carbonylation and hyperbranched polyaramide formation. Rigid, tetrahedral, adamantane-based cores provided enhanced solubility characteristics.

HDL particle. Apo A1 is a cofactor for LCAT (A. Jonas, 2000) and the conversion of cholesterol to CE (Section 2.2) induces the formation of a neutral lipid core and the concomitant change in particle shape. Triacylglycerol molecules are introduced into the core of spherical HDL as a consequence of CE transfer protein activity. The apo A1 amphipathic a-helices are embedded among the PL molecules on the surface of spherical HDL (Fig. 7) but the detailed conformations of the apo A1 molecules are not known. Spherical HDL in plasma can be remodeled via a fusion event into large and small particles by PL transfer protein (K.A. Rye, 2001). Some HDL particles contain both apo A1 and apo A2 molecules and the interactions between these two proteins need to be understood. The presence of apo A2 inhibits HDL remodeling by CE transfer protein and the dissociation of apo A1 molecules to create pre-p-HDL. It seems that apo A2 interacts with apo A1 and reduces the ability of the latter to desorb from the HDL particle surface (K.A. Rye, 2003). 

Formation of the correct disulfide pattern in proteins occurs concomitantly with acquisition of the correct folded form and it is driven by the thermodynamic stability of the native 3D structure. In the initial stages of protein folding processes thermodynamically stable local structures may play an important role (229-232). Thereby short range interactions are essentially implicated to promote stable core structures around which the rest of the protein chain will fold. These sequence-specific short range interactions may suffice for folding of isolated protein fragments Into stable native-like structures as well demonstrated with the bovine pancreatic trypsin inhibitor mono-cystinyl fragment 20-33/43-58 (233). 

A comparison between the Si 2p spectra of the different Si(100)2xl-AM surfaces is presented in Fig. 10. The intensity of the surface component S suggests that it corresponds to emission from the whole uppermost Si layer for Na and K interfaces, while it seems to correspond to half a monolayer for the Rb and Cs interfaces. The values of the S energy splitting with respect to the bulk is presented in Table 9 for different AM. Theoretical calculations predict the formation of symmetric dimers after AM adsorption. This conclusion was supported from the corresponding Si 2p core levels from Na and K interfaces. On the contrary, the Si 2p core levels obtained for Rb and Cs interfaces do not differ much flum those of the clean surface, which suggests a weaker modification of the surface by the adsotbed AM atoms, and the Si dimers may remain asymmetric in this case. The difference in the modification on the Si dimers by the different AM atoms must be related to the Si-AM or AM-AM interactioa A concomitant surface band gap decrease when the size of the AM atom increases has also been detected by inverse photoemission [93Joh]. 

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