Folgeprodukte halogenierter Aldehyde. VII [1] Die Synthese von Di-(1,2,2,2-tetrachloräthyl)-chlorphosphat und Tri-(1,2,2,2-tetrachloräthyl)-phosphat

Derivatives of Halogenated Aldehydes. VII. The Synthesis of Di-(1,2,2,2-tetrachloroethyl) phosphorochloridate and Tri-(1,2,2,2-tetrachloroethyl) phosphate Reaction of phosphorus pentachloride with an excess of chloral in carbon tetrachloride yields a mixture of the tetrachloroethoxy-phosphorus-chlorides 1 — 4 . Following elimination of pentachloroethane by heating gives a mixture of phosphorus oxychloride, tetrachloroethyl phosphorodichloridate 6 , di-(tetrachloroethyl)phosphorochloridate 7 and tri-(tetrachloroethyl) phosphate 8 , which are separated by distillation in vacuo. The data of i.r., n.m.r. and mass spectra are concordant with the assigned structures.     

New Methods for Preparing Submicrometer Powders of The Tungstate‐Ion Conductor Sc2(WO4)3 and its Al and In Analogs

Two new methods for preparing submicrometer powders of M₂(WO₄)₃, M = Sc, In, and Al via combustion synthesis are reported. Stoichiometric combinations of trivalent metal nitrates, ammonium metatungstate, and either urea or carbohydrazide as the fuel were reacted at 550°C, producing amorphous or poorly crystallized powders with an average particle size ranging from 164 to 350 nm. Calcining the powders at 800°C for 1 h produced well‐crystallized, phase‐pure powders with an average particle size ranging from 210 to 711 nm. Powders sintered at 1000°C for 14 h resulted in pellets that were 87%–95% of the theoretical density, which is notably higher than typically obtained from powders prepared by solid‐state reaction. Whereas there was little difference in the microstructure of Al₂(WO₄)₃ pellets prepared with the two different powders, the carbohydrazide‐derived powders resulted in In₂(WO₄)₃ and Sc₂(WO₄)₃ pellets with a larger grain size than those prepared with urea‐derived powders. The electrical conductivity of the sintered pellets, while comparable to that reported for polycrystalline M₂(WO₄)₃ prepared by solid‐state reaction, was strongly influenced by grain‐boundary effects.     

Oxidative degradation of polyamide reverse osmosis membranes: Studies of molecular model compounds and selected membranes

Selected aromatic amides were used to model the chemical reactivity of aromatic polyamides found in thin‐film composite reverse osmosis (RO) membranes. Chlorination and possible amide bond cleavage of aromatic amides upon exposure to aqueous chlorine, which can lead to membrane failure, were investigated. Correlations are made of the available chlorine concentration, pH, and exposure time with chemical changes in the model compounds. From the observed reactivity trends, insights are obtained into the mechanism of RO membrane performance loss upon chlorine exposure. Two chemical pathways for degradation are shown, one at constant pH and another that is pH‐history dependent. An alternative strategy is presented for the design of chlorine‐resistant RO membranes, and an initial performance study of RO membranes incorporating this strategy is reported. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1173–1184, 2003     

Discovery of an Allosteric Ligand Binding Site in SMYD3 Lysine Methyltransferase

SMYD3 is a multifunctional epigenetic enzyme with lysine methyltransferase activity and various interaction partners. It is implicated in the pathophysiology of cancers but with an unclear mechanism. To discover tool compounds for clarifying its biochemistry and potential as a therapeutic target, a set of drug-like compounds was screened in a biosensor-based competition assay. Diperodon was identified as an allosteric ligand; its R and S enantiomers were isolated, and their affinities to SMYD3 were determined (K_D=42 and 84 μM, respectively). Co-crystallization revealed that both enantiomers bind to a previously unidentified allosteric site in the C-terminal protein binding domain, consistent with its weak inhibitory effect. No competition between diperodon and HSP90 (a known SMYD3 interaction partner) was observed although SMYD3–HSP90 binding was confirmed (K_D=13 μM). Diperodon clearly represents a novel starting point for the design of tool compounds interacting with a druggable allosteric site, suitable for the exploration of noncatalytic SMYD3 functions and therapeutics with new mechanisms of action.     

Separation of Indium from Acid Sulfate-Containing Solutions by Ion Exchange with Impregnated Resins

Indium separation using ion exchange resins from acidic polymetallic and very diluted solutions are investigated. Since the selectivity of commercial ion exchange resins have proven to be too low for an effective separation from solutions with high content of other metals, Lewatit® TP 208 was impregnated with common extractants to enhance its properties. By resin impregnation with D2EHPA and Cyanex 272, not only the selective indium recovery was reached but also the resin capacity was increased approx. two times. The best loading and elution performance were shown by Cyanex 272-impregnated Lewatit® TP 208, increasing the indium purity in the eluate from 0.75 % to 85 %.     

Electrochemical characterisation of air electrodes based on La0.6Sr0.4CoO3 and carbon nanotubes

The efficiency of fuel cells suffers from the high activation polarisation at the cathode, where the oxygen reduction reaction takes place. In order to improve the performance, air electrodes composed of carbon nanotubes (CNTs) and the perovskite La_0.6Sr_0.4CoO₃ are produced by two different methods and investigated. In the first method CNTs are directly grown on the perovskite and in the second method CNTs and perovskite are combined by ultrasonic mixing. Their catalytic activity towards oxygen reduction in alkaline solution is evaluated by polarisation curves and electrochemical impedance spectroscopy. Best performance shows the electrode composed of 25 wt% CNTs, 55 wt% La_0.6Sr_0.4CoO₃ and 20 wt% PTFE as binder, produced by ultrasonic mixing. The Nyquist plot of this electrode displays two potential-dependent semi-circles, accounting for processes on the catalyst surface and for processes depending on the morphology of the electrode.     

Phenology of vegetation in Southern England from Envisat MERIS terrestrial chlorophyll index (MTCI) data

Given the close association between climate change and vegetation response, there is a pressing requirement to monitor the phenology of vegetation and understand further how its metrics vary over space and time. This article explores the use of the Envisat MERIS terrestrial chlorophyll index (MTCI) data set for monitoring vegetation phenology, via its estimates of chlorophyll content. The MTCI was used to construct the phenological profile of and extract key phenological event dates from woodland and grass/heath land in Southern England as these represented a range of chlorophyll contents and different phenological cycles. The period 2003–2008 was selected as this was known to be a period with temperature and phenological anomalies. Comparisons of the MTCI-derived phenology data were made with ground indicators and climatic proxy of phenology and with other vegetation indices: MERIS global vegetation index (MGVI), MODIS normalized difference vegetation index (NDVI) and MODIS enhanced vegetation index (EVI). Close correspondence between MTCI and canopy phenology as indicated by ground observations and climatic proxy was evident. Also observed was a difference between MTCI-derived phenological profile curves and key event dates (e.g. green-up, season length) and those derived from MERIS MGVI, MODIS NDVI and MODIS EVI. The research presented in this article supports the use of the Envisat MTCI for monitoring vegetation phenology, principally due to its sensitivity to canopy chlorophyll content, a vegetation property that is a useful proxy for the canopy physical and chemical alterations associated with phenological change.