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The Energyhub@Sea concept is one of the four research applications of the Space@Sea project funded by the EU’s Horizon 2020 research program (GA number: 774253). The focus of this paper is the evaluation of the energy demands of an energy self-sufficient maintenance platform at the location of Helgoland in the North Sea. In view of this, a standardized modular floater was developed as an offshore wind operation and maintenance base, which in the following paper is referred to as an O&M hub. The O&M hub is intended to be equipped with accommodation facilities and various renewable energy infrastructure as well as spare parts logistics, enabling the platform to perform maintenance of offshore gearless wind turbines with a capacity of up to 10 MW. To be energy self-sustaining, an energy supply system for the hub was developed and simulated at a resolution of ten minutes by means of the Top-Energy simulation software, a commercial software tool. As a basis for the simulation, an approach for the automated determination of flexible load profiles, in resolutions of up to ten minutes was developed. This load profile generator creates load profiles on the basis of environmental conditions, technical characteristics, and expected behaviors of the inhabitants. On the basis of the generated load profiles, a first layout (referred to as baseline scenario) for the different components of the energy system was evaluated and tested through simulation. In a second step, three optimization scenarios were developed and simulated with regards to the financial feasibility of the Energyhub.

Volatile isoprenoids regulate plant performance and atmospheric processes, and Amazon forests comprise the dominant source to the global atmosphere. Still, there is a poor understanding of how isoprenoid emission capacities vary in response to ecophysiological and environmental controls in Amazonian ecosystems. We measured isoprenoid emission capacities of three Amazonian hyperdominant tree species – Protium hebetatum, Eschweilera grandiflora, Eschweilera coriacea – across seasons and along a topographic and edaphic environmental gradient in the central Amazon. From wet to dry season, both photosynthesis and isoprene emission capacities strongly declined, while emissions increased among the heavier isoprenoids: monoterpenes and sesquiterpenes. Plasticity across habitats was most evident in P. hebetatum, which emitted sesquiterpenes only in the dry season, at rates that significantly increased along the hydro-topographic gradient from white sands (shallow root water access) to uplands (deep water table). We suggest that emission composition shifts are part of a plastic response to increasing abiotic stress (e.g. heat and drought) and reduced photosynthetic supply of substrates for isoprenoid synthesis. Our comprehensive measurements suggest that more emphasis should be placed on other isoprenoids, besides isoprene, in the context of abiotic stress responses. Shifting emission compositions have implications for atmospheric responses because of the strong variation in reactivity among isoprenoid compounds.

International audience; The marks of prehistoric human societies on tropical forests can still be detected today. Levis et al. performed a basin-wide comparison of plant distributions, archaeological sites, and environmental data. Plants domesticated by pre-Columbian peoples are much more likely to be dominant in Amazonian forests than other species. Furthermore, forests close to archaeological sites often have a higher abundance and richness of domesticated species. Thus, modern-day Amazonian tree communities across the basin remain largely structured by historical human use.Science, this issue p. 925The extent to which pre-Columbian societies altered Amazonian landscapes is hotly debated. We performed a basin-wide analysis of pre-Columbian impacts on Amazonian forests by overlaying known archaeological sites in Amazonia with the distributions and abundances of 85 woody species domesticated by pre-Columbian peoples. Domesticated species are five times more likely than nondomesticated species to be hyperdominant. Across the basin, the relative abundance and richness of domesticated species increase in forests on and around archaeological sites. In southwestern and eastern Amazonia, distance to archaeological sites strongly influences the relative abundance and richness of domesticated species. Our analyses indicate that modern tree communities in Amazonia are structured to an important extent by a long history of plant domestication by Amazonian peoples.

We present an experimental equipment for studying the charge carrier distribution in the interior of bipolar 4H-SiC high power devices by means of laser absorption measurements. Since the light absorption coefficient in a semiconductor depends on the electron and hole concentration, the attenuation of a laser beam transmitted through a sample is an integral function of the local charge carrier density. In order to detect the tiny changes in the light intensity caused by the plasma-optical effect, a highly sensitive measurement set-up has been developed. Its crucial components are a low-noise blue laser and a high-speed and broad-band photo-diode amplifier circuit. Sample preparation is sophisticated and requires special care. We investigated charge carrier profiles in 4H-SiC pin-diodes in the high-injection regime at current densities between 175 A/cm² and 350 A/cm². The measured charge carrier profiles are in good agreement with computer simulations.

Reconfigurable passive superconducting devices for the mm-wave regime offer a large spectrum of novel applications in scientific and industrial remote sensing. We developed a surface mounted Niobium (Nb) MEMS technology that can be integrated with a wide range of cryogenic semiconductor and superconducting circuits. A first generation of circuits using our Niobium SupraMEMS has been optimized for radio astronomical applications. In this paper we present the micro-mechanical and electrical characterization of the devices. Mechanical modeling results in an improved understanding of the specific behavior of metallic cryogenic MEMS devices. The influence of the fabrication procedure on the mechanical properties of the devices and the resulting limitations are discussed. A particular design for improved tuning range has been investigated.

Aim Titanium-coated grafts for breast augmentation are available since 2001 and are used clinically. The titan surface is supposed to improve the tissue compatibility and to lower the infection rate. It was the aim of the present study to validate the antibacterial efficiency of titanium-coated silicone. Material and methods C3H/HcN mice were assigned to four different groups (n=6/group). Silicone without (group I and III) or with (group II and IV) titanium were implanted subcutaneously. Following this in groups III and IV a local contamination was induced with 2 x 10 (7) CFU/0.1 ml Staphylococcus aureus ATCC 25923. Groups I and II were not infected. 14 days after primary operation all animals were euthanized and the grafts harvested. Specimens were examined for signs of infections by macroscopy, histology and microbiology. Results In group I none of the grafts were infected (0/5). In group II (silicone, + titanium, no contamination) one infection was evident due to biting of the animal (1/6). In group III (silicone, no titanium, contamination) an infection was detected in all mice (6/6). The use of titanium, however, did not significantly reduce the infection rate in contaminated animals (group IV, 5/6). Interestingly, tissue integration of titanium-coated grafts was macroscopically reduced compared to non- titanium-coated grafts (group II vs. I). Conclusion The titanium-coated silicone grafts were not effective in protecting infection in vivo. The decreased tissue integration of titanium-coated grafts, however, might reduce the rate of capsular contracture. This potential advantage of titanium needs to be validated in controlled clinical trials.

Objectives. To evaluate the efficacy of silver- or Triclosan-coated prosthetic material compared to Rifampin bonded Dacron concerning their resistance to infection following subcutaneous implantation and contamination with Staphylococcus aureus . Design. Animal experimental study in mice. Material and methods. Thirty-six C3H/HcN mice (Charles River Lab., Sulzfeld, Germany) with a weight between 24 and 27 g were randomised into six groups counting six animals each. Group I: control, gel-sealed dacron graft, group II: gel-sealed dacron graft and local contamination, group III: Intergard ® -Silver-prosthesis and contamination, group IV: silver/gel-sealed dacron prosthesis (test graft) and contamination, group V: Rifampin-bonded gel-sealed graft and contamination, group VI: Triclosan/collagen-coated dacron graft and contamination. Dacron graft material 0.8×1 cm was subcutaneously implanted in mice. Local contamination with 2×10 7 /0.2 ml S. aureus ATCC 25923 was carried out in groups II to VI. On day 14 the animals were killed and the grafts were explanted. The microscopic, histologic and microbiological evaluation of the graft material and the perigraft tissue was performed. Results. In control group I no case of infection was detected. In group II, 6 of 6 animals showed infection. In group III (Intergard ® -Silver) and group IV (silver/gel-test graft) were 6 of 6, in group V (Rifampin) only 1 of 6 grafts and in group VI (Triclosan) 4 of 6 grafts were infected. The difference between the low rate of infection in group V (Rifampin) in comparison to the completely infected groups III and IV (Silver) as well as the control group II was significant. Treatment of grafts with Triclosan could prevent infection only in 1/3 of the cases in group IV. Conclusion. Silver coating failed to prevent graft infection material. A potential antimicrobial property was evident for Triclosan whereas Rifampin-bonded grafts exhibit a significantly reduced infection rate. Thus, silver-coated vascular grafts cannot ensure protection from vascular graft infection.

Pseudomorphic Si 1− x Ge x /Si multi-quantum well p–i–n photodiodes have been grown on (1 1 0) Si by molecular beam epitaxy. Using waveguide geometry we have obtained an external quantum efficiency of 17% at 1.32 μm (TE-polarisation) with a Ge mole fraction of x =0.5. At λ =1.52 μm (TE-polarisation) an external quantum efficiency of 7% has been achieved. From the dependence of photocurrent on device length effective interband absorption coefficients for x =0.5 and 0.37 have been determined quantitatively.

We report progress in the processing and application of poly(phenylene vinylene), PPV, as the emissive layer in electroluminescent diodes, LEDs. Photoluminescence efficiencies above 60% for solid films of PPV are now achieved and single-layer EL diodes achieve luminous efficiencies above 2 Lumen W−1 and peak brightnesses up to 90 000 cd m−2. We discuss measurements of photoconductivity, photovoltaic response, photoluminescence excitation spectra and stimulated emission in films of PPV. We consider that the photoexcited state in these films of PPV is the intrachain singlet exciton. We demonstrate that PPV of this type can show stimulated emission in sub-picosecond pump-probe experiments and can be used as the active lasing medium when incorporated in suitable microcavity structures.

We present a joint experimental and theoretical investigation of the electronic excitations in transition metal‐containing phenylene ethynylenes. The influence of the metal on the nature of the lowest singlet and triplet excited states is characterized. We find that π conjugation occurs through the metal sites, which deeply modifies the optical properties of the conjugated chains. We also analyze the chain‐length dependence of the singlet–singlet, S0→S1, singlet–triplet, S0→T1, and triplet–triplet, T1→Tn, transition energies; both experimental data and theoretical results indicate that the lowest triplet exciton, T1, is strongly localized on a single phenylene ring while the S1 and Tn states extend over a few repeating units. Finally, we estimate the geometric relaxation phenomena occurring in the lowest excited states and perform a Huang–Rhys analysis of the triplet emission spectrum in model systems.

Vertical n-MOSFETs with channel lengths of 85 nm have been grown by MBE. For drain-to-source voltages V/sub DS/>3.3 V, these transistors exhibit hysteresis behavior similar to the reported behavior of fully depleted SOI-MOSFETs. Our results also show a gate voltage controlled turn-off of the drain current when the transistor is operating in the hysteresis mode. We have analyzed this behavior in vertical n-MOSFETs using 2-D device simulation and our results show a threshold value for the hole concentration across the source-channel junction which is required for the forward biasing of this junction. For a transistor operating in the hysteresis mode, we show that the potential barrier height for electron injection across the source-channel junction increases for increasing negative gate voltages during retrace. This results in a gate controlled turn-off of the drain current for SOI and vertical n-MOSFETs operating in the regenerative mode.

We report photocurrent and photoluminescence measurements on blends of the organometallic polymer Pt-poly-yne and C 60 . Due to efficient intersystem crossing, triplet excitons with a binding energy of at least 0.8 eV are created after photoexcitation of Pt-poly-yne. We find that electrons are transferred from Pt-poly-yne onto C 60 by efficient ionization of the triplet exciton. This process gives rise to a photocurrent quantum yield of up to 1–2% in photocells fabricated in a layer structure of indium-tin oxide (ITO)/Pt-poly-yne and 7 wt.% C 60 /aluminium. Evidence for the ionization of the strongly bound triplet excitons is provided by studies of luminescence in the blends. There is only partial quenching of the singlet emission band, but complete quenching of the triplet emission band, and the lifetime of the triplet emission at room temperature is reduced from 2 to 0.1 μs upon addition of 7 wt.% C 60 .

Processible conjugated polymers can be used to fabricate a range of thin-film diodes which can be designed to show good characteristics, both as electroluminescent diodes and also as photoconductive diodes. We discuss the present understanding of the operation of light-emitting diodes which use conjugated polymers for both charge transport and emission. We highlight the improvement to the electroluminescence efficiency that can be produced by the use of two polymer layers selected so that the heterojunction between the two layers is able to confine charge and thus, bring about electron-hole capture to generate excitons at this interface. The nature of these diodes allows fabrication of microcavity structures in which the emission characteristics of the polymer are strongly modified by the allowed cavity modes. This can be used to control the colour of emission and sharpness of the emission bands.

Si:Al, Si:Sb and Si:B surface phases capped by amorphous Si layers were grown by MBE. The formation of the buried interfaces was studied by low-energy electron diffraction and Auger electron spectroscopy which revealed that, except for the stable Si(111)√3 × √3 -B, the majority of the surface phases suffer either from in-plane redistribution (i.e. break-up of surface reconstruction) or surface segregation of the dopant atoms. The electrical characterization of the grown samples included conductivity and Hall effect measurements between 20 and 300 K. It was found that, while the buried Si(111)√3 × √3 -B shows metallic behaviour, the buried Si:Al and Si:Sb surface phases show negligible activation of dopants.

Electronic devices grown by molecular beam epitaxy on a nanometer scale are presented. The use of a vertical device design in combination with delta-doping layers increases the performance of these devices. The vertical design offers the possibility of three dimensional device integration and allows the scaling of MOS field effect transistors down to its physical limits. The excellent crystal quality and doping profile is demonstrated by the very good performance of the grown devices.

We have studied MBE grown amorphous silicon, which was recrystallized at different temperatures for one hour, with a pulsed positron beam. A positron lifetime of 538±10 ps in the as-grown state is attributed to microvoids containing at least 10 vacancies. An incompletely recrystallized sample annealed at 500°C shows an additional long lifetime from ortho-positronium (o-Ps) pick-off annihilation. The o-Ps component disappears for samples, recrystallized at 700°C and above, and the defect lifetime steadily decreases with higher annealing temperature until a value of 310 ps is reached for the layer annealed at 1200°C. This value is explained by positron trapping at dislocations or small vacancy defects stabilized by dislocations or impurities.

We report investigations of electroluminescence and photoluminescence in several soluble ladder-type oligo( para -phenylene)s which we have used in a range of single- and double-layer electroluminescence devices. In double-layer devices which incorporate a thin film of poly(phenylenevinylene) (PPV) as a hole transport layer, yellow emission with 0.6% internal quantum efficiency can be achieved. We find that pure blue emission can be obtained by diluting the luminescent polymer into a poly(9-vinylene carbazole) (PVK) matrix. This gives a blue-emitting electroluminescent device with more than 0.1% internal quantum efficiency.

We have carried out measurements of the photovoltaic effect in a platinum-containing poly-yne. A photocell was fabricated with the platinum poly-yne sandwiched between indium-tin oxide (ITO) and aluminium electrodes. A strong photoresponse was seen at the threshold of the singlet exciton absorption near 3.2 eV, with a quantum yield for carrier generation of up to 0.6%. This is comparable to that found in similar devices made with poly(phenylenevinylene) (PPV). It is known that the presence of the platinum atom gives very efficient crossover from singlet to triplet exciton, and we discuss here the effect of triplet excitons on the photogeneration of charge carriers. We also analyse the spectral response of the photocurrent in terms of charge carrier ranges.

We present a comparative study of two isostructural platinum and palladium poly‐ynes, poly[trans(bis(tributylphosphine))M(1,4) phenylenediethynylene], where M represents either platinum or palladium. Optical excitations are associated with the π‐molecular orbitals, and with strong spin–orbit coupling provided by the transition metal, both singlet and triplet excitations can be measured. The platinum and palladium polymers show similar low‐temperature photoluminescence and photoinduced absorption spectra, with a blue‐shift for the palladium polymer of around 5% for electronic transitions with respect to the platinum polymer. For Pt (Pd) we see strong singlet absorption peaks at 3.26 eV (3.49 eV), and weaker triplet absorption peaks at 2.43 eV (≊2.5 eV) at room temperature. Strong photoluminescence from triplet to ground state peaks at 2.38 eV (2.5 eV), and weak photoluminescence from the excited singlet peaks at 3.06 eV (3.2 eV) at low temperatures. Photoinduced absorption that peaks at 1.49 eV (1.72 eV) i...

Delta-doped Si(100):Sb superlattices with period varying from 1.5 to 100 nm have been characterized by resistivity and Hall-effect measurements. Extremely high mean electron concentrations up to 8 × 10 20 cm −3 and electron mobilities exceeding the values for uniformly-doped bulk Si by a factor of about two have been achieved in short-period superlattices.

Using an Extended Huckel approach, we investigate the electronic structure of a class of metal-containing polyynes (oligomers and polymers). These systems contain square-planar coordinated platinum sites linked by conjugated sequences of acetylenic units. We mainly focus on the evolution of the first optical transition as a function of the molecule size when going from short oligomers to the polymer. Our primary interest is in establishing the contribution of the metal atoms in the conjugation path.

We have measured the optical properties of poly[trans(bis(tributylphosphine))platinum(1,4) phenylenediethynylene)]. In this polymer, conjugated phenylenediethynylene units are linked by square-planar coordinated platinum to form a linear chain. We consider that in contrast to hydrocarbon conjugated polymers, the presence of the heavy metal atom on the chain allows transitions between the singlet and triplet manifolds. We see π conjugation that extends through the metal sites. Strong singlet π-π ∗ absorption peaks at 3.26 eV, and weaker triplet absorption peaks at 2.43 eV at room temperature. Strong photoluminescence from triplet to ground state peaks at 2.38 eV, and weak photolumiscence from the excited singlet peaks at 3.06 eV at low temperatures also see photoinduced absorption which peaks at 1.49 eV, and which shows the same temperature and temporal dependence as the strong luminescence, with a lifetime of 30 μsecs at 10 K. We associate this feature with a triplet to triplet transition. We consider that these measurements provide a direct probe of the exchange energy for the excitons which are primarily located on the π-conjugated section of the chain.

A method for the mesa growth of silicon MBE layers with lateral dimensions down to the nanometer scale is presented. The use of micro-shadow masks, which are compatible to ultra-high-vacuum conditions, allows the epitaxial deposition of laterally structured MBE layers. The electrical characteristics of locally grown p-i-n diodes demonstrate an excellent crystal quality.

Titanium-coated grafts for breast augmentation are available since 2001 and are used clinically. The titan surface is supposed to improve the tissue compatibility and to lower the infection rate. It was the aim of the present study to validate the antibacterial efficiency of titanium-coated silicone.C3H/HcN mice were assigned to four different groups (n=6/group). Silicone without (group I and III) or with (group II and IV) titanium were implanted subcutaneously. Following this in groups III and IV a local contamination was induced with 2 x 10 (7) CFU/0.1 ml Staphylococcus aureus ATCC 25923. Groups I and II were not infected. 14 days after primary operation all animals were euthanized and the grafts harvested. Specimens were examined for signs of infections by macroscopy, histology and microbiology.In group I none of the grafts were infected (0/5). In group II (silicone, + titanium, no contamination) one infection was evident due to biting of the animal (1/6). In group III (silicone, no titanium, contamination) an infection was detected in all mice (6/6). The use of titanium, however, did not significantly reduce the infection rate in contaminated animals (group IV, 5/6). Interestingly, tissue integration of titanium-coated grafts was macroscopically reduced compared to non- titanium-coated grafts (group II vs. I).The titanium-coated silicone grafts were not effective in protecting infection in vivo. The decreased tissue integration of titanium-coated grafts, however, might reduce the rate of capsular contracture. This potential advantage of titanium needs to be validated in controlled clinical trials.

We have developed modified poly(p-phenylene vinylene) (PPV) to improve its performance in organic electroluminescent devices. Encapsulated single-layer devices with this PPV on indium–tin oxide and a calcium cathode have been operated in air for >7000 h at 20 °C and >1100 h at 80 °C without noticeable degradation. Devices fabricated with this PPV, a conducting polymer layer as anode, and a sputtered low work-function alloy as cathode have efficiencies of over 2 lm/W, brightnesses of >600 Cd/m2 at 4 V, and lifetimes of >1400 h driven at ∼100 Cd/m2 initial brightness.

Background Several studies indicate impaired wound healing after trauma and shock. Wound immune cell dysfunction seems to be responsible for altered wound healing after trauma-hemorrhage (T-H). In this respect, administration of the amino acid L-arginine normalized wound immune cell function under those conditions. It remains unknown, however, whether L-arginine improves impaired wound healing after T-H. Methods To study this, male C3H/HeN mice were subjected to a midline laparotomy (i.e., soft tissue trauma induced), and polyvinyl sponges were implanted subcutaneously at the wound site before hemorrhage (35 +/- 5 mm Hg for 90 minutes) or were subjected to sham operation. During resuscitation, mice received 300 mg/kg body weight L-arginine or saline (vehicle). Seven days thereafter, hydroxyproline (OHP), a metabolite of collagen synthesis, was measured in the wound fluid using high-performance liquid chromatography. Collagen types I and III were determined in the wound by Western blot analysis. In addition, wound breaking strength was measured 10 days after T-H or sham operation. Results The results indicate that OHP was significantly decreased in T-H mice. L-arginine, however, restored depressed OHP in the wound fluid in the T-H animals. Similarly, L-arginine treatment prevented a significant depression of collagen I synthesis after T-H. Collagen III was not significantly affected by T-H or L-arginine. Most important, L-arginine increased maximal wound breaking strength after severe blood loss. Therefore, L-arginine improves wound healing after T-H by increasing collagen synthesis. Conclusion Because L-arginine improves wound healing, the results suggest that L-arginine might represent a novel and useful adjunct to fluid resuscitation for decreasing wound complications after trauma and severe blood loss.

A vertical MOSFET with a channel length of 85 nm has been fabricated by molecular beam epitaxy. Compared to previous work, the electrical behaviour has been greatly improved, allowing the use of standard simulation tools for analysing the I-V characteristics. From experimental and theoretical results, we conclude that for vertical MOSFETs, the useful minimum channel length is not limited by the technological constraints but by the physical limits of the electrical performance. The useful minimum channel length is estimated to be 80 nm.

A set of the different Si:Al and Si:B surface phases capped by amorphous Si layers were grown by molecular beam epitaxy (MBE). The formation of the buried interfaces was studied by low‐energy electron diffraction and Auger electron spectroscopy. The conductivity and Hall effect measurements of the grown samples revealed that only the buried Si(111)√3×√3−B surface phase manifests itself as a highly doped degenerated layer, while all the buried Si:Al surface phases covered by amorphous Si show negligible activation of dopants. The difference in electrical properties of the buried surface phases are discussed in terms of the characteristics of their atomic structure.

Pseudomorphic Si1−xGex/Si multi‐quantum well structures for waveguide applications have been grown on (110) Si by molecular beam epitaxy. In a series of samples the Ge fraction x has been varied from x=0.25 to x=0.37 and x=0.50, respectively. We have used photocurrent spectroscopy on mesa diodes to demonstrate that the absorption edge of the strained Si1−xGex quantum wells can be tuned from 1.3 to 1.55 μm by the Ge fraction x. Realization and characterization of single‐mode (110) Si1−xGex rib waveguides with end facets of high optical quality, prepared by cleaving, is reported.

Recently an effective implementation for wavelet transformed operators on three-dimensional data was derived. This novel data structure is used to transform an FDTD scheme with a fast WT into a multi-resolution version. Our approach combines the favorable characteristics, tics of a FDTD scheme and the possibility to resolve the electromagnetic field on locally different resolutions. Since small wavelet coefficients are not updated during the time loop the six field components are computed within such a multi-scale grid instead of the single-resolution Yee grid of FDTD. Finally, resonator structures have been simulated to evaluate the efficiency and applicability of our approach.

A novel epitaxial growth method for fabricating mesa patterns on a micrometer scale has been investigated. Electrical devices have been prepared employing this technique and their characteristics are in good agreement with those of mesa etched devices.