Near-infrared nitrofluorene substitued aza-Boron-dipyrromethenes dyes

The synthesis, spectroscopic properties, and TD-DFT calculations of new aza-Boron-dipyromethene dyes featuring pendant nitrofluorenylethynyl substituents are described. This functionalization allows for moving the luminescence in the NIR, conserving a good quantum yield efficiency.     

Hypercyclic subspaces and weighted shifts

We first generalize the results of León-Saavedra and Müller (2006) [10] on hypercyclic subspaces to sequences of operators on Fréchet spaces with a continuous norm. Then we study the particular case of iterates of an operator T   and show a simple criterion for having no hypercyclic subspace. Finally we deduce from this criterion a characterization of weighted shifts with hypercyclic subspaces on the spaces l^p$l^p$ or _c0$c_0$, on the space of entire functions and on certain Köthe sequence spaces. We also prove that if P is a non-constant polynomial and D   is the differentiation operator on the space of entire functions then P(D)$P(D)$ possesses a hypercyclic subspace.     

Photo-SRM: laser-induced dissociation improves detection selectivity of Selected Reaction Monitoring mode

Selected Reaction Monitoring (SRM) carried out on triple‐quadrupole mass spectrometers coupled to liquid chromatography has been a reference method to develop quantitative analysis of small molecules in biological or environmental matrices for years and is currently emerging as a promising tool in clinical proteomic. However, sensitive assays in complex matrices are often hampered by the presence of co‐eluted compounds that share redundant transitions with the target species. On‐the‐fly better selection of the precursor ion by high‐field asymmetric waveform ion mobility spectrometry (FAIMS) or increased quadrupole resolution is one way to escape from interferences. In the present work we document the potential interest of substituting classical gas‐collision activation mode by laser‐induced dissociation in the visible wavelength range to improve the specificity of the fragmentation step. Optimization of the laser beam pathway across the different quadrupoles to ensure high photo‐dissociation yield in Q2 without detectable fragmentation in Q1 was assessed with sucrose tagged with a push‐pull chromophore. Next, the proof of concept that photo‐SRM ensures more specific detection than does conventional collision‐induced dissociation (CID)‐based SRM was carried out with oxytocin peptide. Oxytocin was derivatized by the thiol‐reactive QSY® 7 C₅‐maleimide quencher on cysteine residues to shift its absorption property into the visible range. Photo‐SRM chromatograms of tagged oxytocin spiked in whole human plasma digest showed better detection specificity and sensitivity than CID, that resulted in extended calibration curve linearity. We anticipate that photo‐SRM might significantly improve the limit of quantification of classical SRM‐based assays targeting cysteine‐containing peptides. Copyright © 2011 John Wiley & Sons, Ltd.     

A Maleimide‐functionalized Tetraphenylethene for Measuring and Imaging Unfolded Proteins in Cells

Collapse of the protein homeostasis (proteostasis) can lead to accumulation and aggregation of unfolded proteins, which has been found to associate with a number of disease conditions including neurodegenerative diseases, diabetes and inflammation. Here we report a maleimide‐functionalized tetraphenylethene (TPE)‐derivatized fluorescent dye, TPE‐NMI, which shows fluorescence turn‐on property upon reacting with unfolded proteins in vitro and in live cells under proteostatic stress conditions. The level of unfolded proteins can be measured by flow cytometry and visualized with confocal microscopy.     

Strain control in germanium nanowires: the use of a silicon nitride shell

The core–shell geometry is a strong tool for inducing and controlling strains in nano‐objects in order to tune their optoelectronic properties. We synthesized and characterized core–shell nanostructures by depositing a non‐epitaxial silicon nitride shell around germanium nanowires. Scanning electron microscopy as well as energy dispersive X‐ray spectroscopy confirms the structural integrity of the heterostructures, and grazing incidence X‐ray diffraction measurements reveal the presence of a radial tensile strain in the Ge nanowires. A control of this strain is then demonstrated up to 0.3% by adjusting the SiN_x shell thickness versus Ge nanowire diameter. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

An example of a nonregular semimonotoneQ-matrix

In their paper, Aganagic and Cottle gave necessary and sufficient conditions for aP ₀-matrix to be aQ-matrix. In his paper, Pang showed that the same characterization holds for anL-matrix.In this paper, we show that a similar characterization for anE ₀-matrix (semimonotone orL ₁-matrix) is not possible. This is done by providing a counterexample to the inclusionE ₀ Q R ₀, thus answering in the negative a question first posed by Pang.     

Photometrische Fluoridbestimmung im Wasser mit Lanthan-Alizarinkomplexan nach Wasserdampf-S?uredestillation

Zusammenfassung Kleine Fhioridmengen im Wasser können aus dem Abdampfrückstand durch Destillation mit überhitztem Wasserdampf nach Seel unter Verwendung von Schwefelsäure rasch isoliert werden. Die photometrische Fluoridbestimmung in den Destillaten im Bereich von 0–30 g F^– erfolgt mit einer einzigen acetonhaltigen und gepufferten Lanthan-Alizarinkomplexanlösung. Dieses Verfahren benötigt einen Zeitaufwand von etwa 45 min, seine Standardabweichung beträgt ± 0,18.

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Photometric determination of fluoride in water using Lanthanum-Alizarin complexane after steam-acid distillation

Small amounts of fluoride in water can be quickly isolated from the residue after evaporation by distillation with superheated steam according to Seel using sulphuric acid. A single acetone containing and buffered lanthanum-alizarin complexane solution is employed for the photometric determination of fluoride in the distillate in the range of 0–30 g F^–. The whole procedure requires about 45 min. The standard deviation is ± 0.18.

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Der Deutschen Forschungsgemeinschaft sind wir für die erhebliche Förderung dieser Arbeit zu Dank verpflichtet.     

ChemInform Abstract: An ab initio Investigation of Bismuth Hydration.

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