Stress-responsive, highly flexible, and breathable nanocomposite sponges show an electrical conductivity from 1.7 to 166.6 S/cm depending on the applied stress. Key for the responsive electrical conductivity of the sponges is the change of percolation of the silver nanowires. These sponges made of short electrospun fibers and silver nanowires could be applied without any amplifier for the operation of automobile bulbs and as an efficient Joule heater. The time required for electric heating (current on) and cooling is very short. Interestingly, the maximum temperature reached by electric heating depends on the compression status. The higher the compression status, the lower is the maximum temperature, which is in accordance with the understanding of Joule heaters. It is noteworthy that these sponges are thermally, chemically, and mechanically very stable. These conductive sponges will open a new area for novel conductive devices with relevance for real-world applications.
269mechanism of chain growth at the interface of the transition metal and of intrinsic fluorite-type oxide for the dissociation of CO on palladium and the formation of high alcohols in syngas conversion.Some points however remain unclear. Thus a high alcohol selectivity is found on the intrinsic fluorite-type oxide. The catalytic site has been assigned to a set formed by transition-metal atom (or adjacent atoms) and a couple of adjacent vacant anionic sites and anionic sites on the support (Scheme VII). Now we may expect from the intrinsic nature of these oxides an ordered distribution of surface anionic vacancies. Thus the specific nature of the catalytic site may induce some special alcohol selectivity rather than a Schulz-Flory distribution. To test this hypothesis, further work must be undertaken in order to prepare catalysts supported on fluorite-type oxides with a controlled and homogeneous distribution of anionic vacancies.Acknowledgment. Many thanks are due to Mr. Lavergne (Universitt de Paris VI), Mrs. Bacri, and Mr. Vennegues (Universitt de Strasbourg) for TEM, BET, and XRD experiments, respectively.The absorption and fluorescence of 0-, m-, and p-distyrylbenzenes on surfaces of polycrystalline silica and alumina were investigated in the adsorbed state. Time-resolved diffuse reflectance transient absorption spectra were recorded following pulsed nanosecond laser excitation at 354 nm. In each case, a long-lived transient was detected and assigned to radical-cation absorption, and in two cases a short-lived transient was observed and assigned to triplet-triplet absorption. The radicals were also detected by ESR spectroscopy after laser excitation. Experimental observations of the laser fluence dependence of the radical-ion formation efficiency are consistent with a mechanism involving the sequential absorption of two photons during the same laser pulse. It is shown that model calculations for one-and two-photon excitation processes give predictions that are in good agreement with the measurements of the triplet-state and radical-ion production, respectively. The radicals decay by electron-ion recombination. The experimentally observed decay curves are well described by a temperature-activated diffusion model. Decay kinetics are discussed and tested in relation to this theoretical treatment.
Integration of electrogenic microorganisms remains a challenge in biofuel cell technology. Here, synthetic biocomposites ("artificial biofilms") are proposed. Bacteria (Shewanella oneidensis) are embedded in a hydrogel matrix (poly(vinyl alcohol)) via wet- and electrospinning, creating fibers and nonwoven gauzes. The bacteria remain viable and metabolically active. The performance is compared to S. oneidensis suspension cultures and "natural" biofilms. While lower than with the suspension cultures, the power output from the fuel cells with the artificial biofilms is higher than with the natural one. Handling, reproducibility, and stability are also better. Artificial biofilms can therefore contribute to resolving fundamental issues of design, scale up, and monosepsis in biofuel cell technology.
The harmful Esca disease in vine plants caused by wood-inhabiting fungi including Phaeomoniella chlamydospora (Pch) is spreading all across the world. This disease leads to poor vine crops and a slow decline or to a sudden dieback of the vine plants. The pruning wounds of vine plants are the main entry point for Pch. While model experiments with aerosol particles recommend electrospun nonwovens as a suitable barrier to block Pch, tests with living spores show clearly that only electrospun fibrous nonwovens do not prevent Pch invasion. However it is found, that with antifungal additives electrospun nonwovens could be applied successfully for blocking of Pch to infect the substrate. Thereby, a highly useful concept for the protection of vine plants against Esca disease is provided which could also serve as a concept for related plant diseases.
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