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Polarized attenuated total reflection Fourier transform infrared spectra were recorded on multilayer stacks of native gastric tubulovesicle membranes. The spectral intensity and linear dichroism were measured for average thicknesses ranging between 0 and 100 bilayers. Atomic force microscopy was used to investigate the orientation of the membranes at the top of the stack. Height profiles were obtained along randomly drawn lines and slopes were computed over various distances. Orientation distribution functions were obtained from the slopes and decomposed into Legendre polynomials. It was found that the second Legendre polynomials coefficient characterizing the membrane orientation was always larger than 0.9. It could therefore be concluded that the membrane tilt does not significantly contribute to the infrared dichroism, even for the largest thicknesses tested.

The Common Agricultural Policy (CAP) of the European Union, technological developments, and commercial pressures to maximise returns and minimise costs, have given rise to a marked intensification of agriculture, particularly in the last 30 years. This highly intensified agriculture has resulted in environmental problems such as erosion. More recently, the CAP reform has introduced agri-environmental measures as a means of combating soil erosion. However, even though the 1992 CAP reform was meant to contribute to overall grassland stabilisation, recent studies point to continued agronomic pressures to plough up grassland. This paper presents a brief synthesis of crop trends and environmental impacts on erosion in Upper Normandy, France. Our analysis is based on data from the French agricultural censuses and on some remote sensing results from the FLOODGEN European project. We also used the simulation capacity of the runoff and erosion STREAM model to test the consequences of grassland decrease in agricultural catchments and to show the efficiency of some agri-environmental measures. Results show that Upper Normandy has lost 200,000 ha of permanent grassland between 1970 and 2000. A simulation performed with the STREAM model shows that the ploughing up of 17% of permanent grassland leads to a sharp rise both in runoff volume (>75%) and soil loss (>85%) within a catchment basin.

Mixed Langmuir–Blodgett films of behenic acid (docosanoic acid) and glucose oxidase have been elaborated. The resulting films transferred on muscovite have been studied by scanning force microscopy. The general organization of the mixed film has been observed. Lateral force microscopy coupled with topographic data obtained with the contact mode, and a selective solubilization process have made possible the distinction between enzyme and behenic acid domains. The general organization of the mixed film may be described as quasi circular domains of glucose oxidase surrounded by a behenic acid monolayer. Both of them are organized on a sublayer of glucose oxidase molecules adsorbed on muscovite.

The dynamic organization of a mixed Langmuir film of glucose oxidase and behenic acid has been studied. Samples of the mixed film transferred after different relaxation times were analyzed by UV-Vis and IR spectroscopies and by lateral force microscopy. The results demonstrate that the enzyme molecules present at the air/water interface arc progressively covered by the behenic acid film. Moreover, we observe an increase of the quantity of glucose oxidase in the mixed film with lime, showing that the adsorption of glucose oxidase under the behenic acid film continues during and after the relaxation process.

The formation of behenic acid monolayers at the air/water interface has been studied in the presence of glucose oxidase. When the enzyme is present in the subphase, spreading of behenic acid at the air/water interface leads to the formation of a mixed film of glucose oxidase and behenic acid. The pressure–area isotherms performed with various concentrations of the enzyme in the subphase showed the incorporation of the enzyme in the monolayer. The dynamics of the mixed films was studied by following the evolution of the film area at a constant pressure and the evolution of the pressure at a constant area. Glucose oxidase dramatically stabilizes the behenic acid film. A limit pressure of incorporation of glucose oxidase in the behenic acid film at the air/water interface was observed at 28 m N /m.

Mixed behenic acid/glucose oxidase ( BA GOx ) films were transferred onto CaF2 slides and gold substrates and characterized by IR and/or UV-visible spectroscopies. The results obtained were confirmed by the study of pressure-area isotherms and led to a diagrammatic model of the structure elaborated by Langmuir—Blodgett technology. This structure could present some domains with GOx organized as islets.