Effect of calcium and trace metals (Cd, Cu, Mn, Ni, Zn) on root iron uptake in relation to chemical properties of the root-excreted ligands.

Interferences of major cations (Ca, Mg) and trace metals (TM, i.e. Cd, Cu, Mn, Ni and Zn) in root Fe uptake were evaluated.

Ecological flexibility and adaptation to past climate change in the Middle Nile Valley: A multiproxy investigation of dietary shifts between the Neolithic and Kerma periods at Kadruka 1 and Kadruka 21.

Human responses to climate change have long been at the heart of discussions of past economic, social, and political change in the Nile Valley of northeastern Africa. Following the arrival of Neolithic groups in the 6th millennium BCE, the Northern Dongola Reach of Upper Nubia witnessed a cultural florescence manifested through elaborate funerary traditions. However, despite the wealth of archaeological data available from funerary contexts, including evidence for domesticated animals and plants as grave goods, the paucity of stratified habitation contexts hinders interpretation of local subsistence trajectories.

4000-year-old hair from the Middle Nile highlights unusual ancient DNA degradation pattern and a potential source of early eastern Africa pastoralists.

Petrous bones and teeth are the skeletal elements most often targeted by researchers for ancient DNA (aDNA) extraction, and the sources of the majority of previously published ancient African genomes. However, the high temperature environments that characterise much of Africa often lead to poor preservation of skeletal remains. Here, we successfully reconstruct and analyse genome-wide data from the naturally mummified hair of a 4000-year-old individual from Sudan in northeastern Africa, after failed attempts at DNA extraction from teeth, petrous, and cranium of this and other individuals from the Kadruka cemeteries.

New developments of the Gas Research Institute method for the permeability measurement of porous media.

This work reports on new developments of an unsteady-state method to measure the permeability and porosity of permeable porous materials, extending the so-called Gas Research Institute method beyond its classical use. These extensions allow one to carry out measurements on samples having a cylindrical shape in the case of one- or three-dimensional (or axisymmetric) flows. They rely on the derivation of the quasi-analytical solutions that are required to interpret the experimental data by solving an inverse problem.

Longitudinal relaxation rate measurements for different signals unveiled by nutation spectroscopy: Application to the characterization of two arrangements experienced by water in a clay network.

Nutation consists in monitoring the motion of nuclear magnetization under the application of a radiofrequency (rf) field. With an appropriate amplitude of the rf field, the nutation frequency depends on the NMR relaxation times. This property offers the possibility of differentiating species having the same Larmor frequency but differing by their relaxation times.

Solvation force and adsorption isotherm of a fluid mixture in nanopores of complex geometry based on fundamental measure theory.

A novel method based on the fundamental measure theory is developed to calculate the solvation force and adsorption isotherm of a Lennard-Jones fluid mixture in complex geometries. Fast Fourier transform and 3D-voxel discretization are used for accurately computing the confined fluid densities in a closed pore of arbitrary geometry. Given the fluid densities, the solvation force distribution at the solid surface can be calculated using a new formulation from either mechanical or thermodynamic approach.

Proton nutation spectroscopy. Application to the quantitation of water in a kaolinite sample.

Nutation consists in monitoring the motion of nuclear magnetization under the application of a radio-frequency field. Depending on the amplitude of the rf field, the nutation frequency may be sensitive to the two longitudinal and transverse relaxation rates R and R, hence the possibility of differentiating species having the same resonance frequency in the laboratory frame (the Larmor frequency) but differing by their relaxation rates, as it may occur for the composite proton NMR signal of water in complex systems. Thus, Fourier transform of the nutation curve should provide separate peaks associated with the different species involved in a composite classical NMR signal.

Measurement of short transverse relaxation times by pseudo-echo nutation experiments.

Very short NMR transverse relaxation times may be difficult to measure by conventional methods. Nutation experiments constitute an alternative approach. Nutation is, in the rotating frame, the equivalent of precession in the laboratory frame.

Electro-osmosis in kaolinite with pH-dependent surface charge modelling by homogenization.

A new three-scale model to describe the coupling between pH-dependent flows and transient ion transport, including adsorption phenomena in kaolinite clays, is proposed. The kaolinite is characterized by three separate nano/micro and macroscopic length scales. The pore (micro)-scale is characterized by micro-pores saturated by an aqueous solution containing four monovalent ions and charged solid particles surrounded by thin electrical double layers.

Sol-gel and isotropic/nematic transitions in aqueous suspensions of natural nontronite clay. Influence of particle anisotropy. 2. Gel structure and mechanical properties.

After size-selection, the phase behavior of aqueous suspensions of nontronite clay was analyzed by osmotic pressure measurements, rheological experiments, and small-angle X-ray scattering. All the measurements confirm that for ionic strength < or =10(-3) M/L, the system is purely repulsive. By combining results from osmotic pressure measurements and X-ray scattering, it appears that the pressure of the system can be well-described using a simple Poisson-Boltzmann treatment based on the interaction between charged infinite parallel planes.

Macroscale modeling of cartilage: mixture theory versus homogenization.

The equations governing the electro-chemo-hydro-mechanical processes in cartilage are derived using the periodic homogenization technique. First the equations at the microscale are recalled. Then the homogenization technique is applied to propagate the physics to the macroscale.