Optical Amplification on the 3P0 3F2 Transition in Praseodymium-doped Fluorozirconate Fiber

Small-signal amplification on the 3P0 3F2 transition in a praseodymium-doped fluorozirconate optical fiber at the 632.8-nm He-Ne wavelength, has realized a slope efficiency of 0.15 dB mW and up to 14 dB gain. Spectroscopic and fiber parame ters, including the pump absorption cross section (sigma a 0.14 0.02 10 24 m2), p the signal emission cross section (sigma e 2.1 0.2 10 24 m2), and the 3P state ( ) s 0 lifetime tau 3 49.8 0.3 mus , determined experimentally, independently of the gain, were used to model the performance of the amplifier. The predictions of the rate equation model were in good agreement with the measured gain.     

Polymerization of Ion-Pair Comonomers of Related Structures

Two ion-pair comonomers of 2-methacryloyloxyethyltrimethyl-ammonium 2-methacryloyloxyethanesulfonate (METMAMES) and 3-acrylamido-3-methylbutyltrimethylammonium 2-acrylamido-2-methylpropanesulfonate have been synthesized. The spontaneous and radical homocopolymerizations of these monomer pairs, wherein no nonpolymerizable counterions are present, have also been studied. Moreover, the intrinsic viscosity of the homocopolymer derived from METMA MES was found to increase with increasing KCl concentration in aqueous solutions.     

Unexpected distribution phenomenon resulting from Cantor series expansions

We explore in depth the number theoretic and statistical properties of certain sets of numbers arising from their Cantor series expansions. As a direct consequence of our main theorem we deduce numerous new results as well as strengthen the known ones.     

Metallic Free Carbon Nanotube Cluster Modified Screen Printed Electrodes for the Sensing of Nicotine in Artificial Saliva

We demonstrate that metallic free carbon nanotube cluster modified screen printed electrodes provide an advantageous sensing methodology for nicotine. The electrochemical oxidation of nicotine is possible at low potentials compared to other commercially available carbon electrodes. Using the carbon nanotube cluster modified screen printed electrodes a detection range of 10 to 1000 μM is possible with a limit of detection of 2 μM. The sensing protocol is shown to be viable in artificial saliva and is promising as a portable and rapid sensor for nicotine in oral fluid (saliva) in areas such as health/life insurance, instances where smoking is banned and also as a point of care test to help improve smoking quit rates.     

Probing Akt-inhibitor interaction by chemical cross-linking and mass spectrometry

The serine/threonine kinase Akt is a critical enzyme that regulates cell survival. As high Akt activity has been shown to contribute to the pathogenesis of various human malignancies, inhibition of Akt activation is a promising therapeutic strategy for cancers. We have previously demonstrated that changes in Akt interdomain arrangements from a closed to open conformation occur upon Akt-membrane interaction, which in turn allows Akt phosphorylation/activation. In the present study, we demonstrate a novel strategy to discern mechanisms for Akt inhibition based on Akt conformational changes using chemical cross-linking and ¹⁸O labeling mass spectrometry. By quantitative comparison of two interdomain cross-linked peptides, which represent the proximity of the domains involved, we found that the binding of Akt to an inhibitor (PI analog) caused the open interdomain conformation where the PH and regulatory domains moved away from the kinase domain, even before interacting with membranes, subsequently preventing translocation of Akt to the plasma membrane. In contrast, the interdomain conformation remained unchanged after incubating with another type of inhibitor (peptide TCL1). Subsequent interaction with unilamellar vesicles suggested that TCL1 impaired particularly the opening of the PH domain for exposing T308 for phosphorylation at the plasma membrane. This novel approach based on the conformation-based molecular interaction mechanism should be potentially useful for drug discovery efforts for specific Akt inhibitors or anti-tumor agents.