Single carbon nanotube optical spectroscopy.

This Minireview discusses novel insights into the electronic structure of carbon nanotubes obtained using single-molecule fluorescence spectroscopy. Fluorescence spectra from single nanotubes are well described by a single, Lorentzian lineshape. Nanotubes with identical structures fluoresce with different energies due to local electronic perturbations. Carbon nanotube fluorescence unexpectedly does not-show any intensity or spectral fluctuations at 300 K The lack of intensity blinking or bleaching demonstrates that carbon nanotubes have the potential to provide a stable, single-molecule infrared photon source, allowing for the exciting possibility of applications in quantum optics and biophotonics.     

New developments in quantitative polymerase chain reaction applied to control the quality of heparins

Heparin is a widely used intravenous anticoagulant comprised of a very complex mixture of glucosaminoglycan chains, mainly derived from porcine intestinal mucosa. Recent contamination of heparin with oversulfated (OS) chondroitin sulfate resulted in a significant number of deaths, triggering a rapid revision of product monographs and the introduction of new analytical methods to limit as far as possible the chances of another occurrence of such a phenomenon. The distribution of heparin-processing units across the globe prevents their complete fool-proof auditing. Therefore, the implementation of additional orthogonal analytical techniques for quality control (QC) of heparin batches is highly important. We perform routine quantitative polymerase chain reaction (Q-PCR) release tests to confirm the quality of all crude heparin batches received by sanofi-aventis. The routine test used provides information on the animal species of origin as requested by the US Pharmacopoeia (USP) and European Pharmacopoiea monographs. Here, we demonstrate that the Q-PCR test is inhibited by OS glycosaminoglycans at concentrations as low as 0.5% (w/w versus heparin) and can be used as an additional safeguard to monitor levels of potentially harmful contaminants without any increased workload. In response to a request from the USP, we also describe the development of a Q-PCR method for monitoring nucleotidic impurities in pure heparin, which is able to detect amplifiable DNA at concentrations lower than 0.1 ng DNA per milligram of heparin. This increased sensitivity makes this modified Q-PCR method a potential candidate for inclusion as a QC requirement in future monographs.     

Den Einfu? einiger Variabler auf die Intensit?t der R?ntgenfluorescenz-strahlung

Zusammenfassung 1-Naphthol kuppelt beim Erwärmen mit Kalium-p-nitrophenylantidiazotat in 2%iger Sodalösung zu einem Azofarbstoff, dessen Alkalisalz in Alkoholen mit blauer Farbe löslich ist. Diese Verbindung ist in Amylalkohol extrahierbar, worauf sich ein spezifischer Nachweis begründen läßt. Der Chemismus der Umsetzung wird diskutiert. Bei Ausführung als Tüpfelreaktion wird eine Erfassungsgrenze von 0,5g erhalten.