Rapid and sensitive method for the determination of propylene oxide in cigarette mainstream smoke by gas chromatography-mass spectrometry

A rapid method using gas chromatography-mass spectrometry for the analysis of propylene oxide in cigarette mainstream smoke is reported. Validation data show the method, which requires a minimum of sample preparation, to be selective, sensitive, reliable, and robust. Propylene oxide is found in the University of Kentucky Reference Cigarettes 1R4F and 2R4F at concentrations of 0.93 and 0.65 microg/cigarette, respectively, with a quantitation limit of 0.135 microg/cigarette.     

Triphasic nanocolloids

Triphasic nanocolloids, that is, nanocolloids with three distinct compartments, were successfully produced by use of electrified co-jetting. Simultaneous manipulation of the three parallel liquid with laminar flows yielded a liquid droplet with three interfaces between the jetting liquids. Under a high electric potential, a single liquid jet was produced from the triple point of the droplet. Separation between the phases was maintained throughout the jetting process and resulted in triphasic nanocolloids. Poly(ethylene oxide), poly(acrylic acid), and poly(acrylamide-co-acrylic acid) solutions were used and verified to be compatible with the process. Fluorescent-labeled biomolecules were selectively incorporated in each phase of the nanocolloids, and confocal laser scanning microscopy was employed for the characterization. Scanning electron microscopy results verified that the sizes of the colloids are in the range of nanocolloids. This simple and versatile technique to fabricate multicompartment nanocolloids is expected to have great impact on drug delivery, molecular imaging, and smart displays.     

Multivariate statistical assessment of polluted soils

This study deals with the application of several multivariate statistical methods (cluster analysis, principal components analysis, multiple regression on absolute principal components scores) for assessment of soil pollution by heavy metals. The sampling was performed in a heavily polluted region and the chemometric analysis revealed four latent factors, which describe 84.5 % of the total variance of the system, responsible for the data structure. These factors, whose identity was proved also by cluster analysis, were conditionally named “ore specific”, “metal industrial”, “cement industrial”, and “steel production” factors. Further, the contribution of each identified factor to the total pollution of the soil by each metal pollutant in consideration was determined.     

Application of the Novel Tandem Process Diels‐Alder Reaction/Ireland‐Claisen Rearrangement to the Synthesis of rac‐Juvabione and rac‐Epijuvabione

The novel tandem process Diels‐Alder reaction/Ireland‐Claisen rearrangement shows a high diastereoselectivity for the Ireland‐Claisen rearrangement starting from the endo‐product of the Diels‐Alder reaction. Based on this mechanistic knowledge, the novel tandem process could be applied to the synthesis of rac‐juvabione.     

On the asymptotic limit of the Navier-Stokes system on domains with rough boundaries

We study the asymptotic behavior of solutions to the incompressible Navier-Stokes system considered on a sequence of spatial domains, whose boundaries exhibit fast oscillations with amplitude and characteristic wave length proportional to a small parameter. Imposing the complete slip boundary conditions we show that in the asymptotic limit the fluid sticks completely to the boundary provided the oscillations are non-degenerate, meaning not oriented in a single direction.     

Ways of selective polycondensation of L‐lysine towards linear α‐ and ε‐poly‐L‐lysine

Polylysines (PL) are highly interesting polymers due to their biocompatibility and their high number of reactive amino groups. So far it was not possible to synthesize them directly from L ‐lysine. Here, we describe two different synthesis routes to selectively polymerize lysine in one batch without the use of protection groups. Applying 1‐ethyl‐3‐(3‐dimethylaminopropyl) carbodiimide as activating agent for the polycondensation of L ‐lysine in water gave selectively linear ε‐PLL. In contrast to this, the polymerization of L ‐lysine in chloroform in the presence of dicyclohexyl carbodiimide and 18‐crown‐6 ether selectively afforded pure α‐PLL. We also assessed the capability of polylysine derivatization by polymer analog reactions with acetic anhydride, methyl iodide and 2,4,6‐trinitrobenzenesulfonic acid. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5053–5063, 2008