We present here a methodology, using holographic interferometry, enabling to
measure the pure surface reaction rate constant of the dissolution of a mineral
in water, unambiguously free from the influence of mass transport. We use that
technique to access to this value for gypsum and we demonstrate that it was
never measured before but could be deduced a posteriori from the literature
results if hydrodynamics is taken into account with accuracy. It is found to be
much smaller than expected. This method enables to provide reliable rate
constants for the test of dissolution models and the interpretation of in situ
measurements, and gives clues to explain the inconsistency between dissolution
rates of calcite and aragonite, for instance, in the literature
A deposited drop of bovine serum albumin salt solution experiences both
gelation and fracturation during evaporation. The cracks appearing at the edge
of the gelling drop are regularly spaced, due to the competition between the
evaporation-induced and relaxation-induced stress evolution. Subsequently, the
mean crack spacing evolves in an unexpected way, being inversely proportional
instead of proportional to the deposit thickness. This evolution has been
ascribed to the change with time of the average shrinkage stress, the crack
patterning being purely elastic instead of evaporation-controlled
We address the mechanical characterization of a calcite paste as a model system to investigate the relation between the microstructure and macroscopic behavior of colloidal suspensions. The ultimate goal is to achieve control of the elastic and yielding properties of calcite which will prove valuable in several domains, from paper coating to paint manufacture and eventually in the comprehension and control of the mechanical properties of carbonate rocks. Rheological measurements have been performed on calcite suspensions over a wide range of particle concentrations. The calcite paste exhibits a typical colloidal gel behavior, with an elastic regime and a clear yield strain above which it enters a plastic regime. The yield strain shows a minimum when increasing the solid concentration, connected to a change in the power law scaling of the storage modulus. In the framework of the classical fractal elasticity model for colloidal suspensions proposed by Shih et al. [Phys. Rev. A, 1990, 42, 4772], we interpret this behavior as a switch with the concentration from the strong-link regime to the weak-link regime, which had never been observed so far in one well-defined system without external or chemical forcing.
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