An evaluation of microextraction/capillary column gas chromatography for monitoring industrial outfalls

Microextraction and capillary-column gas chromatography techniques are applied to plant discharge streams for repetitive wastewater discharge permit analyses. This combination allows the analyst to reduce sample preparation since microextraction replaces both purge-and-trap for volatiles and microextraction for semi-volatiles. An additional advantage is the elimination of a concentration step, which is often a major contributor to low method recoveries. The overall procedure is shown to be more precise than purge-and-trap but slightly less precise than conventional extraction. The results of each method are shown to be equivalent.     

Apparate

Ohne Zusammenfassung     

Untersuchung von Fetten und ?len.

Ohne Zusammenfassung     

UnyLinker dimer impurity characterization and process improvement

Herein, we describe the isolation and characterization of a UnyLinker dimer which, if left uncontrolled, can become incorporated in oligonucleotide products. The dimer is formed as a result of an unusual intermolecular osmium-catalyzed etherification. We demonstrate that by simply replacing H₂O₂ as the co-oxidant with NMO, none of the UnyLinker dimer impurity is formed.     

Integral equation formulation for buoyancy-driven convection problems

An integral equation formulation for buoyancy-driven convection problems is developed and illustrated. Buoyancy-driven convection in a bounded cylindrical geometry with a free surface is studied for a range of aspect ratios and Nusselt numbers. The critical Rayleigh number, the nature of the cellular motion, and the heat transfer enhancement are computed using linear theory. Green's functions are used to convert the linear problem into linear Fredholm integral equations. Theorems are proved which establish the properties of the eigenvalues and eigenfunctions of the linear integral operator which appears in these equations.