The mechanism of iron uptake by the dry biomass of the brown seaweed Sargassum fluitans was investigated at the molecular level using different instrumental techniques. Transmission electron microscopy (TEM) and the chemical microanalysis by electron dispersive spectroscopy (EDS) of the biomass exposed to iron solutions confirmed the deposition of the metal mainly in the cell wall. The analysis of the Fe(II)-exposed biomass by X-ray photoelectron spectroscopy (XPS) indicated the presence of Fe in two states of oxidation in the biomass exposed to ferrous iron solution, whereas only Fe(III) was present in ferric ironexposed biomass, suggesting a partial oxidation of Fe(II) when in contact with the biomass. In both Fe(II)-and Fe(III)exposed samples, XPS indicated iron complexation with sulfate groups in the biomass. The FTIR analysis of metalloaded biomass samples revealed the chelating character of the ion complexation to carboxyl groups as well as the complexation of Fe(III) with sulfur of sulfonate groups in the biomass. This work confirmed the participation of carboxyl groups in the uptake of both Fe(II) and Fe(III), and of sulfonate groups in the uptake of Fe(III) by S. fluitans biomass.

No abstract

No abstract

For thin films where the attenuatioa length is of the same order of magnitude as the film thickness, an exponential fit of the experimental depth profile is proposed. The ratio of the sputtering rates of AI,O, and Ta,O, is thus found to be 0.72 (kO.14).The consistency between measurements performed in the &rent laboratories is excellent in many instances but certain problems are identified, which would deserve further work.

No abstract

No abstract

Apexes of commercial pyramidal silicon scanning microscopy tips were magnetically functionalized by means of local focused electron beam induced deposition. High aspect ratio supertips and local tip coatings with varying apex diameters can be produced by varying exposure time, beam current, and scan mode. The carbonyl precursor Co2(CO)8 was used as source of magnetic metal. Tip performance was tested with magnetic force microscopy (tapping / lift-retrace mode) and magnetically actuated cantilever atomic force microscopy. The deposit contains 34±2 at.% Co, dispersed as 2-5 nm metal nanocrystals in a carbonaceous matrix. Specific surface reactions and Boudouard reactions are proposed to explain the resulting deposit composition measured by Auger spectroscopy. The electrical resistivity is 104 higher than bulk Co resistivity.

This paper presents a study of polymer surfaces modified by laser ablation using poly(ethylene terephthalate) (PET) as a model system. The surface properties induced by static and dynamic ablation with the 193-nm pulsed radiation of an ArF excimer laser (4 x 10(7) W/cm2) in air have been successfully used to control the electroosmotic flow (EOF) in photoablated PET microchannels. Through the creation of well-defined static ablation patterns onto the walls of a trapezoidal channel, it was found that the resulting reduction in the EOF could be controlled. For example, a reduction of 25% in the EOF was observed in 42-microm-deep microchannels when using a static ablation pattern treating 50% of the total wall surface area. A numerical study describing the fluidic behavior induced by a static pattern is also presented. Moreover, X-ray photoelectron spectroscopy has been used to point out surface changes between static and dynamic ablation, thereby demonstrating an ability to create new functionalities in microchannels by laser treatment.