Rapid screening method for the determination of diethylstilbestrol in edible animal tissue by column liquid chromatography with electrochemical detection

A rapid and sensitive screening method for the determination of residues of diethylstilbestrol in edible animal tissue is described. The analyte was extracted from the tissue with tert.-butyl methyl ether, reextracted with 1 M sodium hydroxide and further cleaned up by solid-phase extraction with C18 cartridges. Analysis was performed by isocratic elution with a phosphate-buffered mobile phase, methanol-0.05 M phosphate buffer pH 3.5 (67:33), on a Nucleosil 5-microns C18 column with electrochemical detection at +0.90 V. The average recovery of trans-diethylstilbestrol in spiked samples is 66%, with a standard deviation of 14% (n = 22) in the range 0.5-2.0 microgram/kg. The detection limit is 0.1-0.2 microgram/kg, although at this level other compounds may interfere and give rise to false positive results.     

Dynamic response of shear induced structure solutions in permeable rock

Additives for improving the flow uniformity during secondary oil recovery are partially retained in the rock. The flow improval effects continue to be observed even when the chemical solution is succeeded by pure water. Considerable flushing with water is required before the old permeability of the rock is restored to its original higher level. This effect is extremely advantageous for the application to water flooding profiles in oil recovery. It makes possible an alternating water slug/chemical solution flooding program which further reduces the already relatively small amount of chemicals required in the operation.     

Water Plasticizes Only a Small Part of the Amorphous Phase in Nylon‐6

It is known that Polyamide 6 absorbs water in its amorphous phase. The exact composition of the amorphous phase will determine the uptake process. The heterogeneity in the amorphous phase with respect to plasticization by water uptake is quantified in this paper using NMR relaxometry. It is shown that water occupies and plasticizes only a small part (∼6%) of the nylon matrix. This part is located in between the crystalline domains where polymer chain mobility is higher. At low moisture content (<4%) water molecules are tightly bound to the polymer and have the same dynamics. A highly mobile pool of guest‐hydrogen nuclei is detected starting at a moisture content of 4%. Here, water is absorbed in clusters and the interaction between the polymer chains and water molecules decreases, leading to decoupling of the dynamics of water and polymer.

     

Functionalized dienes via thermolysis of allylic sulfoxides

Thermolysis of allylic sulfoxides is a useful method for the synthesis of functionalized dienes.     

Entropy and Entanglement Bounds for Reduced Density Matrices of Fermionic States

Unlike bosons, fermions always have a non-trivial entanglement. Intuitively, Slater determinantal states should be the least entangled states. To make this intuition precise we investigate entropy and entanglement of fermionic states and prove some extremal and near extremal properties of reduced density matrices of Slater determinantal states.     

Stability and activity of carbon nanofiber-supported catalysts in the aqueous phase reforming of ethylene glycol

Nickel, cobalt, copper and platinum nanoparticles supported on carbon nano-fibers were evaluated with respect to their stability, catalytic activity and selectivity in the aqueous phase reforming of ethylene glycol (230 C, autogenous pressure, batch reactor). The initial surface-specific activities for ethylene glycol reforming were in a similar range but decreased in the order of Pt (15.5 h1 ) >Co(13.0 h1 ) >Ni(5.2 h1 ) while the Cu catalyst only showed low dehydrogenation activity. The hydrogen molar selectivity decreased in the order of Pt (53%)>Co(21%)>Ni (15%) as a result of the production of methane over the latter two catalysts. Over the Co catalyst acids were formed in the liquid phase while alcohols were formed over Ni and Pt. Due to the low pH of the reaction mixture, especially in the case of Co (as a result of the formed acids), significant cobalt leaching occurs which resulted in a rapid deactivation of this catalyst. Investigations of the spent catalysts with various techniques showed that metal particle growth is responsible for the deactivation of the Pt and Ni catalysts. In addition, coking might also contribute to the deactivation of the Ni catalyst.