Temperature-dependent structural changes

The alternate proposal is that both the multiline and g = 4.1 EPR signals arise from the same tetranuclear Mn complex (18,24-25). The conversion of the g = 4.1 EPR signal into the multiline EPR signal upon incubation at 200 K in the dark can then be explained by a temperature-dependent structural change in the Mn site upon... 

The coagulation of hydrolysed aluminium salts has been studied using A1 NMR spectroscopy. The hydrolysis of mixed solutions of Al , Ga ", Ln , and Zr" has been studied by Al and Ga NMR spectroscopy. A C and A1 NMR study of the interaction between Al and tiron, salicylic acid, and phthaUc add has been reported. B, A1, and Si NMR studies of the temperature dependent structural changes in borate, borosilicate, and boro-aluminate Uquids have been reported. The interaction of aluminosilicates by HF has been investigated. Aluminium in polysilicic acid has been speciated using A1 NMR spectroscopy. C, A1 and P NMR spectroscopy has been used to study the formation of Al-NTA-phosphate complexes. The selfdiffusion coefficients of the ATP complex of Al have been studied by H and P pulsed-field gradient NMR spectroscopy. H NMR spectroscopy has been used to study the interaction of Al with phosphatidylcholine vesicles. ... 

Unlike aqueous solutions, a typical Arrhenius dependence for the reverse systems is maintained only before a certain critical temperature (T ), while above this temperature a decrease in occurs with tanperature. The value of is found to coincide with the percolation threshold temperature. We assume that the same temperature induced structural changes of the reverse micelles are responsible for the clnstering of the reverse... 

It is cautioned that this kind of an excellent spectral resolution of [3- C]Ala-bR from PM could be again severely deteriorated, when spectra are recorded either under the conditions of lower humidity than relative humidity (r.h.) 90% or at a temperature below — 10°C. This may be a consequence of similarity of the data between the temperature-dependent spectral change and the dehydration/rehydra-tion behavior of PM studied by measurements of the lamellar spacing by neutron diffraction. Still, no sufficient structural information relating to a 3D structure is available from loops or N- or C-terminal residues under such conditions, however. It is again emphasized that better spectral resolution can be achieved only when the NMR spectra are recorded for C-labeled proteins of 2D crystalline lattice at ambient temperature. 

Diamagnetism, paramagnetism, temperature-dependent spin-changes, spin relaxations, cooperative phenomena, ferromagnetism, ferrimagnetism, antiferromagnetism, determination of transition temperature, determination of magnetic structure... 

Time-temperature superposition is of interest in two contexts. For the experimentalist it is the basis of a technique for substantially increasing the range of times or frequencies over which linear behavior can be determined. And for the polymer scientist, it may provide additional information about molecular structure. It was Ferry [1] who first provided a scientific basis for this procedure. The essence of the concept is that if all the relaxation phenomena involved in G t) have the same temperature dependency, then changing the temperature of a measurement will have the same effect on the data as shifting the data horizontally on the log(time) or log(frequency) axis. Let us say that a change in the temperature from a reference value Tg to a different temperature T has the following effect on all the relaxation times ... 

Above 81.5 K the C(2x 1) structure becomes the more stable. Two important points are, first, that a change from one surface structure to another can occur without any bulk phase change being required and, second, that the energy difference between dtemative surface structures may not be very large, and the free energy difference can be quite temperature-dependent. 

---