Silicon-organic hybrid electro-optical devices

Organic materials combined with strongly guiding silicon waveguides open the route to highly efficient electro-optical devices. Modulators based on the so-called silicon-organic hybrid (SOH) platform have only recently shown frequency responses up to 100 GHz, high-speed operation beyond 112 Gbit/s with fJ/bit power consumption. In this paper, we review the SOH platform and discuss important devices such as Mach-Zehnder and IQ-modulators based on the linear electro-optic effect. We further show liquid-crystal phase-shifters with a voltage-length product as low as V pi L = 0.06 V.mm and sub-mu W power consumption as required for slow optical switching or tuning optical filters and devices

Vermeidung von saatgutbürtigen Krankheiten: Strategien für den Öko-Landbau

Due to legal provisions on the use of organic seed and the generally occurring expansion of organic agriculture the significance of healthy seed in organic farming is increasing. In a project the currently available as well as promising methods and substances shall be tested and evaluated for their use in practice. Results of exemplary investigations concerning the control of Ustilago nuda in spring wheat and spring barley by thermal treatment as well as the control of Tilletia caries in spring wheat by different plant strengtheners are presented

Strategien zur Bekämpfung von Streifen- und Netzfleckenkrankheit der Gerste im Ökologischen Landbau

Barley leaf stripe (Drechslera graminea) and net blotch (Drechslera teres) are important seed transmitted diseases in organic barley cultivation in Europe. In the poster different measures and agents to control both diseases are investigated and discussed. Our research reveals that barley leaf stripe as well as net blotch can be sufficiently controlled in organic farming by physical methods (warm water and hot air treatment) or by the alcoholic plant strengtheners Lebermooser and - less effectively - by Milsana®. The plant protection product Cedomon® was not always sufficiently effective to control barley leaf stripe and net blotch. Depending on the imposed measure and on the barley type (hulless, hulled), variety and seed origin more or less adverse side effects on germination were observed and should thus be considered

Strategien zur Bekämpfung von Brandkrankheiten bei Getreide im Ökologischen Landbau

Getreidebrände als saatgutübertragbare Erkrankungen der Ähre haben im Ökologischen Landbau stärkere Bedeutung erlangt, weil eine Beizung mit hochwirksamen Fungiziden unterbleibt. Eine Bekämpfung ist jedoch zwingend notwendig, weil in der Regel Ertragseinbußen eintreten und die Sporen toxikologisch bedenklich sind. Zudem droht der Saatgutvermehrung Schaden, denn bereits mehr als drei bzw. fünf befallene Pflanzen pro 150 m² führen zur Aberkennung des Basis- bzw. Z-Saatgutes. Resistente Sorten stehen kaum zur Verfügung, denn wegen der Saatbeizung bestand für die Züchtung seit Jahrzehnten keine Notwendigkeit, sich einer Resistenzzüchtung zu widmen. Das spiegelt sich auch in den Zulassungskriterien des Bundessortenamtes wider, wo die Anfälligkeit der Sorten auf Brandkrankheiten nicht berücksichtigt wird. Bei den relevanten Brandkrankheiten handelt es sich bei allen Triticum-Arten um Steinbrand (Tilletia tritici), Zwergsteinbrand (Tilletia controversa) und Flugbrand (Ustilago tritici), bei Gerste um Flugbrand (U. nuda) und Hartbrand (U. hordei) sowie bei Hafer um Flugbrand (U. avenae). Die Bekämpfung der Getreidebrände im Öko-Landbau ist spätestens seit der EU-Verordnung Nr. 1452/2003, welche die Verwendung von Saatgut aus ökologischem Anbau vorschreibt, eine vordringliche Aufgabe der Forschung. In Deutschland werden derzeit verschiedene Forschungsvorhaben zu dieser Problematik durchgeführt (Wilbois et al. 2005; Spieß 2006)

Исследование датчиков рН и удельной электрической проводимости фирмы WTW в системе автоматизированного контроля качества очистки сточных вод

We demonstrate the suitability of microcavities based on circular grating resonators (CGRs) as fast switches. This type of optical resonator is characterized by a high quality factor and very small mode volume. The waveguide-coupled CGRs are fabricated with silicon-on-insulator technology compatible with standard complementary metal-oxide semiconductor (CMOS) processing. The linear optical properties of the CGRs are investigated by transmission spectroscopy. From 3D finite-difference time-domain simulations of isolated CGRs, we identify the measured resonances. We probe the spatial distribution and the parasitic losses of a resonant optical mode with scanning near-field optical microscopy. We observe fast all-optical switching within a few picoseconds by optically generating free charge carriers within the cavity. (C) 2009 Optical Society of Americ

Low-power silicon-organic hybrid (SOH) modulators for advanced modulation formats

We demonstrate silicon-organic hybrid (SOH) electro-optic modulators that enable quadrature phase-shift keying (QPSK) and 16-state quadrature amplitude modulation (16QAM) with high signal quality and record-low energy consumption. SOH integration combines highly efficient electro-optic organic materials with conventional silicon-on-insulator (SOI) slot waveguides, and allows to overcome the intrinsic limitations of silicon as an optical integration platform. We demonstrate QPSK and 16QAM signaling at symbol rates of 28 GBd with peak-to-peak drive voltages of 0.6 Vpp. For the 16QAM experiment at 112 Gbit/s, we measure a bit error ratio of 5.1 × 10-5 and a record-low energy consumption of only 19 fJ/bit

T160‐phosphorylated CDK2 defines threshold for HGF‐dependent proliferation in primary hepatocytes

Liver regeneration is a tightly controlled process mainly achieved by proliferation of usually quiescent hepatocytes. The specific molecular mechanisms ensuring cell division only in response to proliferative signals such as hepatocyte growth factor (HGF) are not fully understood. Here, we combined quantitative time-resolved analysis of primary mouse hepatocyte proliferation at the single cell and at the population level with mathematical modeling. We showed that numerous G1/S transition components are activated upon hepatocyte isolation whereas DNA replication only occurs upon additional HGF stimulation. In response to HGF, Cyclin:CDK complex formation was increased, p21 rather than p27 was regulated, and Rb expression was enhanced. Quantification of protein levels at the restriction point showed an excess of CDK2 over CDK4 and limiting amounts of the transcription factor E2F-1. Analysis with our mathematical model revealed that T160 phosphorylation of CDK2 correlated best with growth factor-dependent proliferation, which we validated experimentally on both the population and the single cell level. In conclusion, we identified CDK2 phosphorylation as a gate-keeping mechanism to maintain hepatocyte quiescence in the absence of HGF

High-speed, low-power optical modulators in silicon

Silicon modulators are maturing and it is anticipated that they are going to substitute state-of-the art modulators. We review current silicon modulator approaches and then discuss the silicon-organic hybrid (SOH) approach in more detail. The SOH approach has recently enabled the operation with an energy consumption of 60 fJ/bit and demonstrated the generation of up to 112 Gbit/s per polarization in a compact silicon modulator of 1.5 mm length

Silicon-Organic Hybrid MZI Modulator Generating OOK, BPSK and 8-ASK Signals for up to 84 Gbit/s

We report on high-speed multilevel signal generation and arbitrary pulse shaping with silicon-organic hybrid (SOH) Mach-Zehnder interferometer (MZI) modulators. Pure phase modulation exploiting the linear electrooptic effect allows the generation of multiple modulations formats at highest speed such as 40-Gbit/s on-off-keying (OOK) and binary-phase-shift keying (BPSK) and 28-Gbd 4-ASK and 8-ASK with data rates up to 84 Gbit/s. Additionally, beside NRZ pulse shaping, for the first time, Nyquist pulse shaping with silicon modulators is demonstrated to enable multiplexing at highest spectral efficiency