Melting experiments

In particular, the laser melting experiment produced two well-differentiated populations of carbon clusters (a) spheroidal diamond particles with a radial texture... 

A problem with studies on inert gas is that the interactions are so weak. Alkali halides are important commercial compounds because of their role in extractive metallurgy. A deal of effort has gone into corresponding calculations on alkali halides such as LiCl, with a view to understanding the structure and properties of ionic melts. Experience suggests that calculations at the Hartree-Fock level of theory are adequate, provided that a reasonable basis set is chosen. Figure 17.7 shows the variation of the anisotropy and incremental mean pair polarizability as a function of distance. 

Newman S, Macdougall JD, Finkel RC (1986) Petrogenesis and °Th- U disequilibrium at Mt. Shasta, Califonua, and in the Cascades. Contrib Mineral Petrol 93 195-206 Nichols GT, Wylhe PJ Stem CR (1994) Subduction zone melting of pelagic sediments constrained by melting experiments. Nature 371 785-788... 

Temperature and pH effects on hemopexin, its domains, and the respective heme complexes have also been examined using absorbance and CD spectroscopy, which reflect stability of the heme iron-bis-histidyl coordination of hemopexin and of the conformation of protein, rather than overall thermodynamic unfolding of the protein. Using these spectral methods to follow temperature effects on hemopexin stability yielded results generally comparable to the DSC findings, but also revealed interesting new features (Fig. 14) (N. Shipulina et al., unpublished). Melting experiments showed that apo-hemopexin loses tertiary... 

In order to confirm formation of the oT15/oA15 duplex, additional techniques were used to characterize the complex. Stoichiometery analysis (Job s plot binding) supported the formation of a 1 1 complex. CD-assisted melting experiments performed on the... 

Hurwitz S. and Navon O. (1994) Bubble nucleation in rhyolitic melts experiments at high pressure, temperature, and water content. Earth Planet. Sci. Lett. 122, 267-280. 

Recall that the secondary-structure model for RNA is a model - and a crude one at that. It neglects pseudo knots and other tertiary interactions, does not take deviations from the additive nearest neighbor energy model into account, and is based on thermodynamic parameters extracted from melting experiments by means of multidimensional fitting procedures. Thus, you cannot expect perfect predictions for each individual sequence. Rather, the accuracy is on the order of 50% of the base pairs for the minimum free energy structure. 

A so-called kissing-loop complex forms by Watson-Crick base pairing between the loops of two hairpins. Melting experiments with one such complex, between hairpins named tar and tar, easily resolve disruption of... 

Equation (21.34) can only be used to fit data for which Kohs is small, 5T.02, under the initial conditions of the experiment ([Mg2+] = 0). We use a melting experiment under the buffer conditions of the isothermal titration to establish a value for Kohs at the titration temperature. If a significant fraction of the RNA is folded in the absence of Mg2+, baseline (s) are subtracted by an appropriate method and the data are normalized to the appropriate range of 9, 9 = Kohs/(1 + Kohs) for the initial zero Mg2+ concentration point and 1.0 for the maximum value of 9. The following equation works well for fitting these curves ... 

Because of the potential source of error just noted, it is advisable to have independent confirmation of Kohs in the absence of Mg2+. For the A-riboswitch RNA, moderate concentrations of the most tightly binding ligand (2,6-diaminopurine) do in fact stabilize the native structure to some degree at 20 °C from the melting experiments used to generate Fig. 21.4B,... 

It is useful at this point to consider the polymer melt experience as it flows from the reservoir into, through, and out of the capillary tube. In the entrance region shown in... 

The polymer melt experience briefly described above is complex and varied it involves steady, accelerating, fully developed, and exit flows and strain recovery. It is not surprising, then, that this apparently simple experiment is used to study not only the viscous but also the elastic nature of polymer melts. 

DTA experiments indicated a second transition zone 0 + a occurs between 1710 10 °C (X-phase) and 1575 15 °C (Y-phase). Finally a continuous liquidus-solidus relation characterizes the high-temperature a-solid solution series with melting temperatures of 1770 10 °C (X-phase) and 1700 35 °C (Y-phase). Melting experiments performed with various X—Y phase mixed crystals resulted in inhomogeneous quenched products. Since a small vapor loss could hardly be prevented, some exsolved molybdenum metal was always observed. 

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