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Some Characteristics of Positive and Bipolar Lightning Flashes Recorded on the Säntis Tower in 2010 and 2011
No full textSCI-STI-FRDES
Comparison between macaques’ and humans’ kinematics of prehension: the role of morphological differences and control mechanisms
No full textLAS
The GigaView multiprocessor multidisk image server
No full textProfessionals in various fields such as medical imaging, biology, and civil engineering require rapid access to huge amounts of pixmap image data. Multimedia interfaces further increase the need for large image databases. To fulfil these requirements, the GigaView parallel image server architecture relies on arrays of intelligent disk nodes, each disk node being composed of one processor and one disk. This contribution reviews the design of the GigaView hardware and file system, compares it to other storage servers available on the market, and evaluates fields of applications for the architectureLS
Charge Generation and Photovoltaic Operation of Solid-State Dye-Sensitized Solar Cells Incorporating a High Extinction Coefficient Indolene-Based Sensitizer
No full textAn investigation of the function of an indolene-based organic dye, termed D149, incorporated in to solid-state dye-sensitized solar cells using 2,2',7,7'- tetrakis(N,N-di-p-methoxypheny-amine)-9,9' - spirobifluorene (spiro-OMeTAD) as the hole transport material is reported. Solar cell performance characteristics are unprecedented. under low light levels, with the solar cells delivering up to 70% incident photon-to-current efficiency (IPCE) and over 6% power conversion efficiency as measured under simulated air mass (AM) 1.5 sun light at 1 and 10 mW cm(-2). However, a considerable nonlinearity. in the photocurrent as intensities approach "full sun" conditions is observed and the devices deliver up to 4.2% power conversion efficiency under simulated sun light of 100 mW cm(-2). The influence of dye-loading upon solar cell operation is investigated and the thin films are probed via photoinduced absorption (PIA) spectroscopy, tune-correlated single-photon counting (TCSPC), and photoluminescence quantum efficiency (PLQE) measurements in order to deduce the cause for the non ideal solar cell performance. The data ! suggest that electron transfer from the photoexcited sensitizer into the TiO2 is only between 10 to 50% efficient and that ionization of the photo excited dye via hole transfer directly to spiro-OMeTAD dominates the charge generation process: A persistent dye bleaching signal is also observed and assigned to a remarkably high density of electrons "trapped" within the dye phase, equivalent to 1.8 x 10(17) cm(-3) under full sun illumination. it is believed that this localized space charge build-up upon the sensitizer is responsible for the non-linearity of photocurrent with intensity and nonoptimum solar. cell performance under full sun conditions.LP
The critical role of the underlayer material and thickness in growing vertically aligned carbon nanotubes and nanofibers on metallic substrates by chemical vapor deposition
No full textVertically aligned carbon nanotubes and nanofibers are grown on metallic Ta and Pd underlayers at temperatures below 500°C. Controlling the size of the grains of the underlayer film is critical because this leads to a more uniform distribution of catalyst dots, which in turn results in vertical alignment of the carbon nanostructures. Rapid and limited heating and appropriate materials selection can also be used to limit catalyst/underlayer reactions that hinder or suppress carbon nanostructure growth or that lead to entangled growth. Control of catalyst reactivity with metallic underlayers is significant because growth on conductive substrates is notoriously difficult, but needed for many applications such as the use of carbon nanostructures in microelectronic circuits. © 2010 WILEY-VCH Verlag GmbH & Co. KGaA.NANOLA
Photonic and Optoelectronic Devices Based on Mesoscopic Thin Films
No full textDye-sensitized solar cells (DSCs) are one of the most promising environmental friendly and low material costs photovoltaic devices. DSCs accomplish the separation of the optical absorption and charge separation processes by the association of a sensitizer as light absorbing material with a wide band gap semiconductor. The mesoscopic morphology of the semiconductor produces an interface with a huge area endowing these systems with intriguing optoelectronic properties. In recent years the DSC has made excellent progress. Conversion efficiencies over 12% and excellent stability have been reached rendering it a credible alternative to conventional p-n junction photovoltaic devices. Commercial exploitation of DSCs started in 2009. In addition to the DSC, Laboratory of Photonics and Interfaces performs research in the field of photoelectrochemical water splitting and materials design for organic light emitting diodes.LP
Electric vehicle charging station using fuel cell technology: Two different scenarios and thermodynamic analysis
No full textThis study evaluates two different scenarios of an integrated system to generate electricity for a charging station using proton exchange membrane fuel cell (PEMFC) and solid oxide fuel cell (SOFC). To improve the efficiency, the exhaust heat of these two fuel cells are recovered by two different bottoming power cycles of Kalina Cycle (KC) and Organic Rankine Cycle (ORC). The system is designed for a 100 kW charging station capable to charge five cars simultaneously, assuming a standard car used in daily life with a battery capacity of 36 kWh and a range of 220 km. Thermodynamic analysis of the system is performed in different current densities from 0.5 A/cm(2) to 0.8 A/cm(2). In the first scenario, results indicated that the overall energy efficiency of the system is 58.47% at 0.5 A/cm(2) and 49% at 0.8 A/cm(2), while that of the second scenario is 43.21% at 0.5 A/cm(2) and 35% at 0.8 A/cm(2). To improve the dynamic response of the system, a high capacity battery and a supercapacitor were integrated to the fuel cell system. It was found that a hybrid combination of the battery and supercapacitor improve the performance of the system. (C) 2021 The Author(s). Published by Elsevier Ltd.SCI-STI-JV
Electronic relaxation induced by interaction between diatomics in low-temperature matrixes
No full textFluorescence (phosphorescence) excitation spectra as well as luminescence spectra and decay times were investigated for NO in N2 and mixed N2/Kr matrixes. All Rydberg states rapidly relax to the ground state in mixed matrixes with the N2 molar fraction exceeding cN2 = 0.35. This dependence on the N2 concn. is attributed to the complete fluorescence quenching of all NO mols. with at least one N2 nearest neighbor. The vibrational levels of the B 2P valence states strongly coupled to the Rydberg state are also depopulated. The general picture of relaxation channels is discussed. [on SciFinder (R)]LS
Microbial Ecology of Methanotrophy in Streams Along a Gradient of CH4 Availability
No full textDespite the recognition of streams and rivers as sources of methane (CH4) to the atmosphere, the role of CH4 oxidation (MOX) in these ecosystems remains poorly understood to date. Here, we measured the kinetics of MOX in stream sediments of 14 sites to resolve the ecophysiology of CH4 oxidizing bacteria (MOB) communities. The streams cover a gradient of land cover and associated physicochemical parameter and differed in stream- and porewater CH4 concentrations. Michealis–Menten kinetic parameter of MOX, maximum reaction velocity (Vmax), and CH4 concentration at half Vmax (KS) increased with CH4 supply. KS values in the micromolar range matched the CH4 concentrations measured in shallow stream sediments and indicate that MOX is mostly driven by low-affinity MOB. 16S rRNA gene sequencing identified MOB classified as Methylococcaceae and particularly Crenothrix. Their relative abundance correlated with pmoA gene counts and MOX rates, underscoring their pivotal role as CH4 oxidizers in stream sediments. Building on the concept of enterotypes, we identify two distinct groups of co-occurring MOB. While there was no taxonomic difference among the members of each cluster, one cluster contained abundant and common MOB, whereas the other cluster contained rare operational taxonomic units (OTUs) specific to a subset of streams. These integrated analyses of changes in MOB community structure, gene abundance, and the corresponding ecosystem process contribute to a better understanding of the distal controls on MOX in streams.RIVE