Main LUC types in the Seine-et-Marne department in 2003.

<p>Main LUC types in the Seine-et-Marne department in 2003.</p

Self-Interference of Exciton Emission in Organic Single Crystals Visualized by Energy-Momentum Spectroscopy

We employ energy-momentum spectroscopy on isolated organic single crystals with micrometer-sized dimensions. The single crystals are grown from a thiophene-based oligomer and are excellent low-loss active waveguides that support multiple guided modes. Excitation of the crystals with a diffraction-limited laser spot results in emission into guided modes as well as into quasi-discrete radiation modes. These radiation modes are mapped in energy-momentum space and give rise to dispersive interference patterns. On the basis of the known geometry of the crystals, especially the height, the characteristics of the interference maxima allow one to determine the energy dependence of two components of the anisotropic complex refractive index. Moreover, the method is suited to identify the orientation of molecules within (and around) a crystalline structure

Averaged temporal variation of the standardized three composition and seven configuration variables from the multivariate analyses for the overall landscapes of the study area between 1982 and 2003 (DLUC for dominant LUC, MLUC for minority LUC).

<p>Averaged temporal variation of the standardized three composition and seven configuration variables from the multivariate analyses for the overall landscapes of the study area between 1982 and 2003 (DLUC for dominant LUC, MLUC for minority LUC).</p

Standard deviations of the standardized temporal changes (Chg_LandVar_i) for the composition and configuration variables and their sum (DLUC for dominant LUC, MLUC for minority LUC).

<p>Standard deviations of the standardized temporal changes (Chg_LandVar_i) for the composition and configuration variables and their sum (DLUC for dominant LUC, MLUC for minority LUC).</p

Areas of the six LUC types in 1982 and 2003 in hectares, their respective proportion of the study area as a percentage, and their percentage change with respect to their area in 1982.

<p>Areas of the six LUC types in 1982 and 2003 in hectares, their respective proportion of the study area as a percentage, and their percentage change with respect to their area in 1982.</p

Matrix conversion of LUC changes between 1982 and 2003 in hectares.

<p>Matrix conversion of LUC changes between 1982 and 2003 in hectares.</p

Maps of the changes in the amplitude of the temporal composition and configuration between 1982 and 2003.

<p>The amplitudes are computed as the sum of the absolute values of the changes of the standardized composition and configuration variables between 1982 and 2003.</p

Ecological Engineering Approaches to Improve Hydraulic Properties of Infiltration Basins Designed for Groundwater Recharge

Infiltration systems are increasingly used in urban areas for groundwater recharge. The reduction of sediment permeability by physical and/or biological processes is a major problem in management of infiltration systems often requiring expensive engineering operations for hydraulic performance maintenance. To reduce these costs and for the sake of sustainable development, we proposed to evaluate the ability of ecological engineering approaches to reduce the biological clogging of infiltration basins. A 36-day field-scale experiment using enclosures was performed to test the influences of abiotic (light reduction by shading) and biotic (introduction of the macrophyte <i>Vallisneria spiralis</i> (L.) or the gastropod <i>Viviparus viviparus</i> (Linnaeus, 1758)) treatments to limit benthic biofilm biomass and to maintain or even increase hydraulic performances. We coupled biological characterization of sediment (algal biomass, bacterial abundance, total organic carbon, total nitrogen, microbial enzymatic activity, photosynthetic activity, and photosystem II efficiency) with hydraulic conductivity measurements to assess the effects of treatments on sediment permeability. The grazer <i>Viviparus viviparus</i> significantly reduced benthic biofilm biomass and enhanced hydraulic conductivity. The other treatments did not produce significant changes in hydraulic conductivity although <i>Vallisneria spiralis</i> affected photosynthetic activity of biofilm. Finally, our results obtained with <i>Viviparus viviparus</i> are promising for the development of ecological engineering solutions to prevent biological fouling in infiltration systems

Consequences of a Single Double Bond within a Side Group on the Ordering of Supramolecular Polymers

By combining atomic force microscopy experiments and full-atomistic computer simulations, we compared the two-dimensional ordering dynamics of two variants of supramolecular polymers of bis-urea molecules which differed only by a single <i>cis</i>-double bond in their side groups. At early stages of ordering, the double bonds favored kinks at the level of individual molecules, which induced transient steric constraints hindering the spontaneous formation of long supramolecular polymers. In addition, due to these kinks, molecule–substrate interactions were disturbed. At later stages, however, due to a progressively increasing number of established directional hydrogen bonds between molecules, the self-assembly process improved and thereby increased the length of the supramolecular polymers. Large domains of micrometer-long and aligned supramolecular polymers were formed, epitaxially guided by the graphite substrate and having a constant width consistent with the length of the molecule. Thus, introducing flexible (kinked) side chains can reduce the nucleation probability and slow the growth of supramolecular polymers due to incommensurablility with the crystalline substrate. Such an elementary control of nucleation and growth via the introduction of a single double bond represents a powerful pathway for the formation of large ordered domains of aligned one-dimensional supramolecular polymers

Revealing Order and Disorder in Films and Single Crystals of a Thiophene-Based Oligomer by Optical Spectroscopy

Depending on processing conditions, ordered microstructures of conjugated oligomers or polymers exhibit variable amounts of grain boundaries, lattice disorder, and amorphous (disordered) regions. These structural details can be determined very precisely. Their correlations with optical or electronic properties, however, are very difficult to establish, because, for example, optical spectra are usually averaged over regions with different degrees of disorder. In an attempt to facilitate the interpretation of optical spectra, we performed systematic studies on thin films and μm-sized single crystals of thiophene-based conjugated molecules, which allowed identifying the relative contributions of ordered and disordered regions in optical emission spectra. A detailed multipeak analysis of the emission spectra showed that the peak positions, the energies of the emitted photons, showed only minor changes, independent if highly ordered or rather disordered samples were examined. However, the relative emission intensity changed significantly between samples. In particular, for highly ordered single crystals the purely electronic 0–0 transition nearly vanished, that is, it was essentially optically forbidden as theoretically predicted. Thus, changes in emission probability are correlated with the degree of structural order in semiconducting conjugated systems and provide a possibility to quantify structural order