Relating viscoelastic nanoindentation creep and load relaxation experiments

Indentation load relaxation (ILR) experiments with indentation depths in the submicron range are described. Under appropriate conditions, the ILR data are found to yield flow curves of the same shape as those based on conventional load relaxation data. Variations in flow properties as a function of depth in submicron metal films deposited on a hard substrate are detected by the experiments described.

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Indentation Load Relaxation Experiments on Al-Si Metallizations

MRS Proceedings ◽

10.1557/proc-188-165 ◽

1990 ◽

Vol 188 ◽

Cited By ~ 1

Author(s):

W. R. LaFontaine ◽

B. Yost ◽

R. D. Black ◽

Che-Yu Li

Keyword(s):

Flow Behavior ◽

Indentation Load ◽

Load Relaxation ◽

Depth Of Penetration ◽

Flow Curves ◽

Bulk Specimen ◽

Load Relaxation Test ◽

Relaxation Experiments ◽

Film Substrate ◽

Penetration Depths

ABSTRACTIndentation load relaxation (ILR) experiments with indentation depths in the submicron range are described. The observed flow behavior of a 1μm thick A1-2%Si film deposited on a silicon substrate depended on the depth of penetration. For shallow penetration depths, the shape of the flow curves obtained from this sample are similar to those obtained from a conventional load relaxation test of a bulk specimen. For penetration depths close to the film/substrate interface, the influence of the substrate on the film's deformation behavior was observed.

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Correlation between electrical and rheological measurements on sewage sludge

Water Practice & Technology ◽

10.2166/wpt.2007.002 ◽

2007 ◽

Vol 2 (1) ◽

Author(s):

E. Dieudé-Fauvel ◽

J.-C. Baudez ◽

P. Coussot ◽

H. Van Damme

Keyword(s):

Sewage Sludge ◽

Rheological Parameters ◽

Clear Correlation ◽

Electrical Measurements ◽

Rheological Measurements ◽

Sludge Characterization ◽

Relaxation Experiments ◽

Rheological Experiments ◽

The One ◽

Microstructure Of The Material

In order to improve sewage sludge characterization for both dewatering and agricultural spreading, we have studied their electrical and rheological properties. On the one hand, electrical measurements give a picture of the microstructure of the material (charges, particles mobility), whereas on the other hand, rheological experiments describe its macrostructure (consistency). The interactions of the matter are the link between them. Our results showed that sludge becomes more conductive when its dry content (for a defined composition) or the temperature increases, and also during aging. In parallel its apparent viscosity increases with the dry content but decreases with the temperature or during aging. In each case a clear correlation was found between electrical and rheological parameters. This relationship clearly depends on sludge composition, and also on parameters such as the temperature, the observation frequency, the velocity range in the case of relaxation experiments. Finally, those types of experiments can be correlated to improve the comprehension of sludge structure and consistency characterization.

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Conformational dynamics and thermodynamics of protein–ligand binding studied by NMR relaxation

Biochemical Society Transactions ◽

10.1042/bst20110750 ◽

2012 ◽

Vol 40 (2) ◽

pp. 419-423 ◽

Cited By ~ 46

Author(s):

Mikael Akke

Keyword(s):

Ligand Binding ◽

Bound States ◽

Conformational Dynamics ◽

Nmr Relaxation ◽

Titration Calorimetry ◽

Conformational Entropy ◽

Chain Order ◽

Ligand Interactions ◽

Galectin 3 ◽

Relaxation Experiments

Protein conformational dynamics can be critical for ligand binding in two ways that relate to kinetics and thermodynamics respectively. First, conformational transitions between different substates can control access to the binding site (kinetics). Secondly, differences between free and ligand-bound states in their conformational fluctuations contribute to the entropy of ligand binding (thermodynamics). In the present paper, I focus on the second topic, summarizing our recent results on the role of conformational entropy in ligand binding to Gal3C (the carbohydrate-recognition domain of galectin-3). NMR relaxation experiments provide a unique probe of conformational entropy by characterizing bond-vector fluctuations at atomic resolution. By monitoring differences between the free and ligand-bound states in their backbone and side chain order parameters, we have estimated the contributions from conformational entropy to the free energy of binding. Overall, the conformational entropy of Gal3C increases upon ligand binding, thereby contributing favourably to the binding affinity. Comparisons with the results from isothermal titration calorimetry indicate that the conformational entropy is comparable in magnitude to the enthalpy of binding. Furthermore, there are significant differences in the dynamic response to binding of different ligands, despite the fact that the protein structure is virtually identical in the different protein–ligand complexes. Thus both affinity and specificity of ligand binding to Gal3C appear to depend in part on subtle differences in the conformational fluctuations that reflect the complex interplay between structure, dynamics and ligand interactions.

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