Gel electrophoresis for elemental speciation purposes

This work has shown that gel electrophoresis is a relevant fractionation method for trace elements bound to or complexed by macromolecules. Furthermore, detection methods of the trace elements that do not rely on the use of radiotracers were applied, making this combination relevant for materials of human origin, where the use of radioactive material is restricted for reasons of safety

Aluminum Alloy Stamping with a First Warm Step and a Second Cold Step

This paper describes a way to simultaneously improve the formability and final strength of 6xxx aluminum alloys by doing a two-step stamping process, namely a warm forming step followed by a cold forming step

Capabilities and limitations of gel electrophoresis for elemental speciation : a laboratory's experience

Gel electrophoresis is a fractionation/separation technique that yields valuable information in the field of metalloproteomics, often referred to as metallomics. This paper is based on four years of practical experience of the authors' lab in this domain and highlights the capabilities and limitations of gel electrophoresis. Pitfalls of the technique were recognized by identifying the origin of artefacts in the separation, species degradation being the most important. Gel electrophoresis can be accomplished under either native or denaturing conditions. The speciation of vanadium and selenium among serum and yeast proteins, respectively, is sued to illustrate these two major modes. The most powerful approach is two-dimensional denaturing gel electrophoresis. This review of the methods used in our laboratory also descries the application of the two major detection techniques, autoradiography on the one hand and electrothermal vaporization - or laser ablation (LA)-inductively coupled plasma-mass spectrometry (ICP-MS) on the other

Contributions of Satellite Images in the Diachronic Study of the Stanley-Pool Sub Basin (Congo- Brazzaville)

With increased population now days, there is a marked change in morphology of the land when it comes the analysis of space images (satellite) using remote sensing. This study covers a sample application of the use of spatial imagery for mapping land cover in the Stanley-Pool (Congo - Brazzaville). The approach used here is based on confrontation of satellite data acquired on different dates (2001-2005). These images were chosen because of realization a demographic growth during this period. The results of this study show a great advance in land occupation which affected the whole of the autonomous port of Brazzaville

Diffusion rates of Cu adatoms on Cu(111) in the presence of an adisland nucleated at FCC or HCP sites

The surface diffusion of Cu adatoms in the presence of an adisland at FCC or HCP sites on Cu(111) is studied using the EAM potential derived by Mishin {\it et al.} [Phys. Rev. B {\bf 63} 224106 (2001)]. The diffusion rates along straight (with close-packed edges) steps with (100) and (111)-type microfacets (resp. step A and step B) are first investigated using the transition state theory in the harmonic approximation. It is found that the classical limit beyond which the diffusion rates follow an Arrhenius law is reached above the Debye temperature. The Vineyard attempt frequencies and the (static) energy barriers are reported. Then a comparison is made with the results of more realistic classical molecular dynamic simulations which also exhibit an Arrhenius-like behavior. It is concluded that the corresponding energy barriers are completely consistent with the static ones within the statistical errors and that the diffusion barrier along step B is significantly larger than along step A. In contrast the prefactors are very different from the Vineyard frequencies. They increase with the static energy barrier in agreement with the Meyer-Neldel compensation rule and this increase is well approximated by the law proposed by Boisvert {\it et al.} [Phys. Rev. Lett. {\bf 75} 469 (1995)]. As a consequence, the remaining part of this work is devoted to the determination of static energy barriers for a large number of diffusion events that can occur in the presence of an adisland. In particular, it is found that the corner crossing diffusion process for triangular adislands is markedly different for the two types of borders (A or B). From this set of results the diffusion rates of the most important atomic displacements can be predicted and used as input in Kinetic Monte-Carlo simulations

Verdad, racionalidad, universidad. Perspectivas sobre la universidad y la teología en la actualidad

The university teaching of theology, which was historically considered as the highest discipline, is often times deemed a problem. It seems that one of the principal causes of this state of affairs is the conflict, conceived by some thinkers, between reason and authority. Pope Benedict XVI offers both a diagnosis and a remedy to the «crisis of university» by developing the idea of «extended rationality». Through this idea, secular universities could, without compromising its demand of rationality, provide room for theology, even though it does not adopt the way theology is imparted in confessional universities.La enseñanza de la teología en la universidad se plantea a menudo como un problema, y sin embargo, históricamente fue considerada la disciplina más alta. Parece que uno de los principales motivos de esta situación es el conflicto que algunos ven entre razón y autoridad (1). El papa Benedicto XVI ha presentado a la vez un diagnóstico y un remedio a la «crisis de la universidad», desarrollando de diversas maneras la idea de una «racionalidad ampliada» (2). Por esta vía, la universidad secular podría abrir un espacio a la enseñanza de la teología manteniendo al mismo tiempo su exigencia de racionalidad, incluso si la naturaleza de esta enseñanza pudiera adoptar una forma distinta a la de la teología que se imparte en las universidades confesionales (3)

Enhancement of the electronic contribution to the low temperature specific heat of Fe/Cr magnetic multilayer

We measured the low temperature specific heat of a sputtered $(Fe_{23\AA}/Cr_{12\AA})_{33}$ magnetic multilayer, as well as separate $1000\AA$ thick Fe and Cr films. Magnetoresistance and magnetization measurements on the multilayer demonstrated antiparallel coupling between the Fe layers. Using microcalorimeters made in our group, we measured the specific heat for $4<T<30 K$ and in magnetic fields up to $8 T$ for the multilayer. The low temperature electronic specific heat coefficient of the multilayer in the temperature range $4<T<14 K$ is $\gamma_{ML}=8.4 mJ/K^{2}g-at$. This is significantly larger than that measured for the Fe or Cr films (5.4 and $3.5 mJ/K^{2}mol$ respectively). No magnetic field dependence of $\gamma_{ML}$ was observed up to $8 T$. These results can be explained by a softening of the phonon modes observed in the same data and the presence of an Fe-Cr alloy phase at the interfaces.Comment: 20 pages, 5 figure