High-Capacity Conductive Nanocellulose Paper Sheets for Electrochemically Controlled Extraction of DNA Oligomers

Highly porous polypyrrole (PPy)-nanocellulose paper sheets have been evaluated as inexpensive and disposable electrochemically controlled three-dimensional solid phase extraction materials. The composites, which had a total anion exchange capacity of about 1.1 mol kg−1, were used for extraction and subsequent release of negatively charged fluorophore tagged DNA oligomers via galvanostatic oxidation and reduction of a 30–50 nm conformal PPy layer on the cellulose substrate. The ion exchange capacity, which was, at least, two orders of magnitude higher than those previously reached in electrochemically controlled extraction, originated from the high surface area (i.e. 80 m2 g−1) of the porous composites and the thin PPy layer which ensured excellent access to the ion exchange material. This enabled the extractions to be carried out faster and with better control of the PPy charge than with previously employed approaches. Experiments in equimolar mixtures of (dT)6, (dT)20, and (dT)40 DNA oligomers showed that all oligomers could be extracted, and that the smallest oligomer was preferentially released with an efficiency of up to 40% during the reduction of the PPy layer. These results indicate that the present material is very promising for the development of inexpensive and efficient electrochemically controlled ion-exchange membranes for batch-wise extraction of biomolecules

Documents pour servir à l'étude du Néolithique : III. — La Station de Ségor

Octobon E., Chainet M. A. Documents pour servir à l'étude du Néolithique : III. — La Station de Ségor. In: Bulletin de la Société préhistorique de France, tome 29, n°9, 1932. pp. 354-407

Documents pour servir à l'étude du Néolithique : III. — La Station de Ségor

Octobon E., Chainet M. A. Documents pour servir à l'étude du Néolithique : III. — La Station de Ségor. In: Bulletin de la Société préhistorique de France, tome 29, n°9, 1932. pp. 354-407

Evidence of extended fine structures in the Auger spectra: A new approach for surface structural studies

International audienc

Fine structure in electron energy-loss and Auger spectra : Applications to the local geometry determination of surfaces and interfaces

International audienc

Simultaneous recovery of heavy metals (Pb, Cd, Zn) from diluted solutions by electroextraction technique

Cadmium is mainly used in galvanoplasty and stabilisation of plastic materials. It accumulates continuously in soils. The analysis of soil samples gave concrete evidence of increase of concentration of this element during the past centunary [1]. Furthermore Cd and Pb attack selectively the kidneys and the liver with enzymatic troubles. The work has enabaled to put into evidence the contribution of the presence of resin to the conventional electrodialysis process. The optimal conditions for the elimination of Cd++, Zn++ and Pb++ ions were determined. These included influence of resin, imposed current density, flow rate of the feeding solution (diluat), different supporting electrolytes used during the electroextraction (HNO3, HCl and H2SO4) and concentration of the solution to be treated [2-3-4]. Furthermore the competition between the electroextraction of the metallic cations Cd++, Zn++and Pb++ was investigated for different mixtures

Initial stages of the electrocrystallization of copper from non-cyanide alkaline bath containing glycine

International audienceAn electrochemical study on the initial stages of copper electrodeposition onto nickel substrate from non-cyanide alkaline bath containing glycine as complexing agent is presented in this work. The studied parameters were copper concentration, glycine concentration, and deposition potential. Upon scanning in the negative direction, one cathodic peak was observed, which is associated to copper electrodeposition from CuL2 complex at pH 10.0 (where L− is the anion form of glycine). Analysis of the chronoamperograms indicates time-dependent nucleation mechanisms. A progressive nucleation mechanism without overlap of diffusion zones, which involved an electron transfer reaction (at short times) and a progressive nucleation mechanism with overlap of diffusion zones (at long times). Non-linear fitting methods were applied to obtain the growth and nucleation kinetic parameters from theoretical equations proposed to describe this system