Note on the interpretation of electroluminescence images using their spectral information

We show how to use the reciprocity between electroluminescence and solar cell quantum efficiency for the simulation and interpretation of electroluminescence images. The analysis of the spectral properties of the electroluminescence images obtained by using different short- and long-pass filters yields information about surface recombination velocity, bulk diffusion length and reflection of the back side in flat and textured solar cells.     

Potent Inhibition of Acid Sphingomyelinase by Phosphoinositide Analogues

The different mammalian sphingomyelinases are involved in cell regulation, apoptosis and inflammatory events. Recent reports suggest pharmacological potential especially for inhibitors of the acid sphingomyelinase. Phosphatidyl inositol‐3,5bisphosphate (PtdIns3,5P₂) is the most potent selective acid sphingomyelinase inhibitor known to date. In the present study, we synthesized analogues of PtdIns3,5P₂ for initial structure–activity‐relationship (SAR) studies. We identified an inhibitor that is easy to synthesize, that has superior chemical and biophysical properties when compared to PtdIns3,5P₂ and that should be stable against virtually all phospholipases. Last but not least, the new inhibitor partially protected cells from dexamethasone‐induced cell death.     

Processing behavior and mechanical properties of autopolymerizing hypoallergenic denture base polymers

Driven by the phenomenon of increasing irritations and allergic reactions of dental prosthesis carriers preferably due to residual methyl methacrylate monomer in conventional dental materials, autopolymerizing hypoallergenic denture base polymers were prepared as two‐component materials in the shape of paste/paste‐ or powder/liquid systems. The processing behavior of these materials was investigated regarding the processing and solidification times also in dependence on the polymerization catalyst concentration, whereas the whole processing and curing characteristics and the final polymer properties were evaluated by dynamic mechanical analysis in shear mode in the temperature range from ?145°C to 200°C. The mechanical properties of the hypoallergenic denture base polymers were validated regarding stiffness (flexural modulus E') and fracture toughness (maximum factor of loading intensity , total work of fracture ) and the effects of monomer composition, kind of resin powder, impact modification by the liquid component, and water immersion on these properties were investigated. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41378.     

Improved Second Generation Iron Pincer Complexes for Effective Ester Hydrogenation

Hydrogenation of esters to alcohols with a well‐defined iron ^iPr2PNP pincer complex has been recently reported by us and other groups. We now introduce a novel and sterically less hindered ^Et2PNP congener that provides superior catalytic activity in the hydrogenation of various carboxylic acid esters and lactones compared to the known complex. Successful hydrogenation proceeds under relatively mild conditions (60 °C) with lower catalyst loadings.

     

Palladium‐Catalyzed Carbonylative Synthesis of 2,3‐Disubstituted Chromones

An unexpected palladium‐catalyzed carbonylative synthesis of 2,3‐disubstituted chromones has been developed. Starting from 2‐bromofluorobenzenes and ketones, the corresponding chromones were produced in good yields. By control experiments, this transformation was found to proceed through a sequential carbonylation/Claisen–Hasse rearrangement/intramolecular nucleophilic aromatic substitution approach (S_NAr). More specifically, the reaction sequence started with a palladium‐catalyzed carbonylation of the ketone with o‐bromofluorobenzene to give the vinyl benzoates, which subsequently transformed into 1,3‐diketones via a Claisen–Hasse rearrangement. The final products were produced after an intramolecular S_NAr reaction of the in situ formed 1,3‐diketone.

     

Natural production of organic bromine compounds in Berlin Lakes

Berlin surface waters are characterized by elevated concentrations of organic bound bromine (up to 35 microg/L) in late summer. Organic bromine compounds in lakes are of significant importance because human life is closely connected to fresh water. Apart from recreational use, fresh water is frequently used for the production of drinking water, e.g., after bank filtration. Therefore the source, particularly the mechanism responsible for the formation is studied. Field studies indicate that the organic bromine compounds, measured as adsorbable organic bromine (AOBr), are autochthonous. Staggered maxima concentrations of chlorophyll-a, DOC and AOBr indicate that phototrophic organisms might contribute to the AOBr after death. The involvement of phototrophic organisms was established in the laboratory using surface water and/or cultures of organisms. Light and the presence of phototrophic organisms are essential for an AOBr production. Phototrophic organisms incorporate bromide, which is released randomly and after cell death. A part of the incorporated bromide is used for the formation of organic bromine compounds in the cell. After death of the organisms the brominated compounds and the incorporated bromide are released into the water phase, and an extracellular AOBr production can lead to a further formation of AOBr, most probably due to the parallel release of haloperoxidases.     

Aluminium in wild mushrooms and cultivated Agaricus bisporus

 The aluminium content in wild mushrooms (n = 271, 19 species) and in cultivated Agaricus bisporus (n = 15) was determined by graphite furnace atomic absorption spectroscopy. With an aluminium content of 30 – 50 μ/g dry matter (DM) Boletus and Xerocomus species, the most well-known and most popular mushrooms, proved to be poor in aluminium. Several species of the genus Suillus, Macrolepiota rhacodes, Hypholoma capnoides as well as individual samples of Russula ochroleuca and Amanita rubescens contained high aluminium concentrations of about 100 μg/g DM and more. Cultivated Agaricus bisporus had the lowest aluminium content, i. e. 14 μg/g DM. The site, its geological origin as well as the mushroom species influenced the aluminium content in the fruitbodies: these factors require further investigation. Mushrooms do not contribute significantly to aluminium intake by humans. Received: 23 January 1997     

Capacity-achieving probability measure for a reduced number of signaling points

Putting bounding constraints on the input of a channel leads in many cases to a discrete capacity-achieving distribution with a finite support. Given a finite number of signaling points, we determine reduced subsets and the corresponding optimal probability measures to simplify the receiver design. The objective for the subset selection is to keep the channel quality high by maximizing mutual information and cutoff rate. Two approaches are introduced to obtain a capacity-achieving probability measure for the reduced subset. The first one is based on a preceded signaling point selection while the second one chooses the signaling points and corresponding probabilities simultaneously. Numerical results for both approaches show that using only a small number of signaling points achieves a very high mutual information compared to channels utilizing the full set of signaling points.     

WDX-Analysis of the New Superconductors RO1−x F x FeAs and Its Consequences on the Electronic Phase Diagram

Polycrystalline samples of RO_1−x F _x FeAs (0≤x≤0.25) (R=La, Sm, Gd) were investigated by wavelength-dispersive X-ray spectroscopy (WDX) in the electron microscope to determine the composition of the samples, in particular the fluorine content. It was found that the measured fluorine content can deviate considerably from the initial weight. In the lanthanum compound LaO_1−x F _x FeAs, we found good agreement mainly for x≥0.05, but for x<0.05 the fluorine hardly goes into the sample. For the samarium compound we measured less than half the fluorine in the sample as initially weighed at all fluorine concentrations. These measured values are taken into account when drawing the electronic phase diagrams of LaO_1−x F _x FeAs and SmO_1−x F _x FeAs. This leads to a more consistent picture of both of the diagrams in comparison to the plot of the initial weight.