Reaction of a sterically protected diphosphane with n-butyl lithium leads to a bicyclic diphosphanide structure. The bicyclic structure, in which each lithium atom coordinates to only one solvent ...molecule, is retained in solution. Display omitted
•Sterically protected diphosphanes have been synthesized.•Experimental data concerning stereochemistry correlates with DFT calculations.•Solid state structures are reported for three novel diphosphanes.•Distribution of products strongly depends on n-BuLi:educt ratios.
Reaction of two equivalents of lithium hypersilylphosphanide (hypersilyl, Hyp=tris(trimethylsilyl)silyl) with dichlorotetramethyldisilane at low temperatures gives HypPH–SiMe2–21, a compound with high steric protection on both phosphane functionalities. Dehydrogenation reaction of 1 with n-butyl lithium yields the dilithiated 2.1.1 bicyclic phosphanide salt HypPLi–SiMe2–22. The bicyclic structure is confirmed by NMR spectroscopy and X-ray diffraction analysis. As a major byproduct during the synthesis of 1 as well as via reaction of 2 with dichlorotetramethyldisilane, 1,4-diphospha-cyclosilahexane HypP–(SiMe2)2–23 is obtained. X-Ray diffraction analysis shows exclusive formation of the trans-conformer 3a in the solid state, which is supported by calculations at the level of density functional theory (DFT).
Hintergrund/Einleitung:
Bei der Leberregeneration kommt es innerhalb von Stunden nach 2/3-Leberresektion zu einer Zunahme des Zellvolumens, was als als proliferativer Stimulus von Bedeutung sein ...könnte.
Zielsetzung:
Da Osmolyt- und Ionentransporter an der Regulation des Zellvolumens beteiligt sind, wurde die Regulation von Transportproteinen bei der Leberregeneration mittels Microarray-Genchipanalyse untersucht.
Material und Methoden:
Bei Wistar-Ratten wurde eine 2/3-Leberresektion durchgeführt. Kontrolltiere wurden einer Scheinoperation ohne Leberresektion unterzogen. Zu den Zeitpunkten 3h, 6h, 12h, 24h, 36h und 48h wurde Lebergewebe entnommen. Gesamt-RNA der Rattenlebern diente als Template für die Analyse mittels eines für Rattenleber spezifischen Microarrays, in dem aus etwa 400 Genen verschiedene Transportergene enthalten waren. Zur weiteren Analyse ausgewählter Gene wurden Proteinlysate der verschiedenen Rattenlebern per SDS-PAGE aufgetrennt und einer Immunodetektion unterzogen.
Ergebnisse u. Schlussfolgerungen:
Auf RNA-Ebene ist eine differenzierte Regulation von Transportergenen in den ersten 48h der Leberregeneration zu verzeichnen. Zu den herabregulierten Genen zählen die Osmolyttransporter BGT1 und SMIT, die kanalikulären Transporter MRP2 und BSEP, sowie die sinusoidalen Transporter NTCP und OATP1–4. Zu den heraufregulierten Transportergenen zählen insbesondere der Na-Kalium-2-Chlorid-Kotransporter 1 (NKCC1), die Aminosäuretransporter ATA2 und Slc3A2, sowie OATP5. Hitzeschockproteine werden ebenfalls heraufreguliert. Die NKCC1-Expression wurde auf Protein- und RNA-Ebene weiter untersucht. Schon in den ersten Stunden nach 2/3-Leberresektion kommt es zu einer Induktion des NKCC1- Proteins. Die maximale Steigerung (ca. 5fach) der NKCC1-Expression ist nach 24h erreicht, danach sinkt die Expression wieder langsam ab. Da NKCC1 der wichtigste Ionentransporter für die Zellvolumen-regulatorische K+-Aufnahme ist, könnte seine Induktion von Bedeutung bei der Regulation der Leberregeneration sein. Die genaue physiologische Bedeutung muss jedoch in weiteren Untersuchungen geklärt werden.
A bio-optical model coupled with the radiative transfer model Hydrolight was used to create 18,000 synthetic ocean colour spectra corresponding to open ocean and coastal waters. The bio-optical model ...took into account the optical properties of the three oceanic constituents, chlorophyll-a, suspended non-chlorophyllous particles and coloured dissolved organic matter (CDOM) as well as of normal seawater. The resulting spectra were input into multilayer perceptron neural network algorithms with the aim of computing the original concentrations of chlorophyll-a, non-chlorophyllous particles and CDOM initially input into the bio-optical model. The process of training the neural networks is essential for the accuracy of the inversion the neural net performs on the coupled bio-optical and radiative transfer models. The objective of this paper is to investigate the performance difference of a neural network trained with untransformed as opposed to logarithmically transformed data.
Artificial radiance sets were used as inputs to Multi-layer Perceptron and multilinear regression algorithms to study their retrieval capabilities for optically active constituents in sea water. The ...radiative transfer model Hydrolight was used to produce 18,000 artificial reflectance spectra representing various case 1 and case 2 water conditions. The remote sensing reflectances were generated at the Medium Resolution Imaging Spectrometer (MERIS) wavebands 412, 442, 490, 510, 560, 620, 665 and 682 nm from randomly generated triplet combinations of chlorophyll a, non-chlorophyllous particles and CDOM (Coloured Dissolved Organic Matter) concentrations. These reflectances were contaminated with different noise terms, before they were used to assess the performance of multilayer perceptron and multilinear regression algorithms. The potential of both algorithms for retrieving optically active constituents was demonstrated with the neural network showing more accurate results for case 2 scenarios.
The radiative transfer model Hydrolight was used to produce 18 000 artificial reflectance spectra representing case 1 and case 2 water conditions. Remote sensing reflectances were generated at the ...MERIS wavebands 412, 442, 490, 510, 560, 620, 665 and 682 nm from randomly generated triplet combinations of chlorophyll a, non-chlorophyllous particles and coloured dissolved organic matter concentrations. These spectra were used to train multilayer perceptron neural network algorithms to perform the inversion from input reflectances to these three optically active substances. A method is proposed that establishes the neural network output error sensitivity towards changes in the individual input reflectance channels. From the output error produced for each reflectance change, a hypothesis about the importance of each band can be made. Results suggest a strong weight associated to the 620 nm band for the estimation of all three substances.
In April 2000 a base line survey was conducted on the larval distribution of commercial fish species off the west, north and south coasts of Ireland. Ichthyoplankton samples and in situ CTD data were ...collected, whilst simultaneously capturing remote sensing images of chlorophyll and sea surface temperatures. The survey sampling area covered the Celtic Sea from the Irish south coast to 49 degree N, the western shelf including the Porcupine Bank and the northern shelf up to the Stanton Bank. The sample grid design was based on the international mackerel & horse mackerel egg survey with station spacings of 0.5 degree latitude and 0.5 degree longitude. Ichthyoplankton samples were collected with a Gulf III plankton sampler, which was deployed on oblique tows from the surface to within 5 metres of the bottom (200m max). A self-logging CTD sensor (Promonitor) was attached to the Gulf and recorded depth, temperature and salinity profiles for each deployment. Results from the Promonitor CTD showed that strong temperature and salinity gradients were encountered during the survey. Lowest temperatures coincided with lowest salinity in the North Channel of the Irish Sea while highest salinities and temperatures were found to the south west of Ireland.Thermal fronts were found in the eastern Celtic Sea and on the north west coast of Ireland.The AVHRR images showed a progressive increase in surface temperatures in the Celtic Sea and west of Ireland. Highest surface chlorophyll concentrations were associated with cooler less saline water in the Irish Sea and the coastal areas around Ireland. In the western Celtic Sea surface chlorophyll concentrations increased as the survey progressed to form a phytoplankton bloom towards the end of the survey. Larvae of interest showed distinct distribution patterns, with some species being confined to particular areas or spawning grounds while others were spread over the whole survey area. The survey identified two important larval hotspots: Cod larvae were concentrated in the eastern Celtic Sea, where other gadoid species such as haddock, whiting, pollack and saithe were also found in high numbers.This area is associated with the Celtic Sea front and shows increased primary productivity, which could present a favourable environment for successful larval survival. Stations in the southwest of Ireland sustained high concentrations of hake, megrim and mackerel larvae. The waters with high numbers of these three species stretched from shallow inshore stations to deeper ones along the continental shelf and were characterised by high temperatures and salinities. SeaWIFS satellite images suggest the formation of a phytoplankton bloom within this larval hotspot, which would provide the necessary resources for successful larval growth.
Commission of the European Communities (FP7-KBBE-2007-1 project no. 212881)
MEFEPO (Making the European Fisheries Ecosystem Plan Operational) is a group of ecologists, economists, management experts ...and fisheries scientists who are trying to make ecosystem based fisheries management a reality in Europe. This Atlas is intended for policy makers, managers and interested stakeholders. Its purpose is to provide an ecosystem overview of the North Western Waters area (NWW) Regional Advisory Council (RAC) area. The Atlas includes general summary information on the physical and chemical features, habitat types, biological features, birds, mammals, fishing activity and other human activities of the NWW region. Background material on four NWW case study fisheries is presented (North East Atlantic Mackerel, Northern Hake, Dublin Bay Prawn and Scallops). This NWW Atlas was produced by the Marine Institute, Ireland as part of the EU funded MEFEPO project.
The Sentinel-3 (S3) mission is developed as part of the Copernicus Space Component (CSC) Programme to fulfil the space-based observation requirements in response to European policy priorities with a ...particular emphasis on the Copernicus core services as identified by the Commission.
The Sentinel-3 (S3) mission is developed as part of the Copernicus Space Component (CSC) Programme to fulfil the space-based observation requirements in response to European policy priorities with a ...particular emphasis on the Copernicus core services as identified by the Commission. The Sentinel-3 main objectives are to measure sea-surface topography, sea- and land-surface temperature and ocean- and land-surface colour in support of ocean forecasting systems, and for environmental and climate monitoring. A series of Sentinel-3 satellites will ensure global, frequent and near-real time ocean, ice and land monitoring, with the provision of observation data in routine, long term (up to 20 years of operations) and continuous fashion, with a consistent quality and a high level of reliability and availability. Sentinel-3 carries an Ocean and Land Colour Instrument (OLCI), a Sea and Land Surface Temperature Radiometer (SLSTR), a SAR Radar altimeter (SRAL) supported by a Microwave Radiometer (MWR) and a suite of orbit determination instruments. A full description of Sentinel-3 can be found in Donlon et al (2012). The paper will focus on S3 optical payloads described in Nieke et al (2015) and Coppo et al (2015).
