Selective catch and release of a synthetically useful phosphine ligand

The selective catch and release of the synthetically useful (o-biphenyl)(t-butyl)₂P from basic and non basic compounds, utilizing solid phase supported sulfonic acid sources is demonstrated.     

High-performance liquid chromatographic determination of 4-methylimidazole in sheep plasma and in ammoniated tall fescue hay

A method for 4-methylimidazole (4MI) extraction and quantitation in body fluids and forage samples was developed. The procedures involve ion-pair extraction of the compound with the quantitation done by ion-pair liquid chromatography. The results indicate that this high-performance liquid chromatographic method is sensitive, reproducible and more rapid than others that have been previously used. The mean recovery of 4MI from plasma and tall fescue (Festuca arundinacea) hay samples were above 95 and 85%, respectively. The versatility of the procedure makes it suitable for the determination of 4MI in body fluids and in forage samples.     

Screw dislocation pile-ups in two phase materials of finite rigidity

The arrangement of discrete screw dislocations piled-up under the action of a uniform applied stress against the welded interface between different elastically isotropic half-spaces has been determined by representing the pile-up as a continuous distribution of infinitesimal dislocations. The dislocation slip plane is inclined at an arbitrary angle $\text{1}\text{2}\text{aπ}$ to the normal to the interface, assuming a to be a rational number. The singular integral equation expressing the condition for static equilibrium of the dislocations under a constant applied stress is solved by a method based on the Wiener-Hoph technique with the Mellin transform, and from this solution the mean density of dislocations and the stress field of the pile-up are determined.     

Adsorption of sophorolipid biosurfactants on their own and mixed with sodium dodecyl benzene sulfonate, at the air/water interface

The adsorption of the lactonic (LS) and acidic (AS) forms of sophorolipid and their mixtures with the anionic surfactant sodium dodecyl benzene sulfonate (LAS) has been measured at the air/water interface by neutron reflectivity, NR. The AS and LS sophorolipids adsorb with Langmuir-like adsorption isotherms. The more hydrophobic LS is more surface active than the AS, with a lower critical micellar concentration, CMC, and stronger surface adsorption, with an area/molecule ～70 ?(2) compared with 85 ?(2) for the AS. The acidic sophorolipid shows a maximum in its adsorption at the CMC which appears to be associated with a mixture of different isomeric forms. The binary LS/AS and LS/LAS mixtures show a strong surface partitioning in favor of the more surface active and hydrophobic LS component but are nevertheless consistent with ideal mixing at the interface. In contrast, the surface composition of the AS/LAS mixture is much closer to the solution composition, but the surface mixing is nonideal and can be accounted for by regular solution theory, RST. In the AS/LS/LAS ternary mixtures, the surface adsorption is dominated by the sophorolipid, and especially the LS component, in a way that is not consistent with the observations for the binary mixtures. The extreme partitioning in favor of the sophorolipid for the LAS/LS/AS (1:2) mixtures is attributed to a reduction in the packing constraints at the surface due to the AS component. Measurements of the surface structure reveal a compact monolayer for LS and a narrow solvent region for LS, LS/AS, and LS/LAS mixtures, consistent with the more hydrophobic nature of the LS component. The results highlight the importance of the relative packing constraints on the adsorption of multicomponent mixtures, and the impact of the lactonic form of the sophorolipid on the adsorption of the sophorolipid/LAS mixtures.     

Comparison of yellow poplar pretreatment between NREL digester and sunds hydrolyzer

Single-stage cocurrent dilute acid pretreatments were carried out on yellow poplar (Liriodendron tulipifera) sawdust using an as-installed and short residence time modified pilot-scale Sunds hydrolyzer and a 4-L bench-scale NREL digester (steam explosion reactor). Pretreatment conditions for the Sunds hydrolyzer, installed in the NREL process development unit (PDU), which operates at 1 t/d (bone-dry t) feed rate, spanned the temperature range of 160 – 210°C, 0.1 – 1.0% (w/w) sulfuric acid, and 4-10-min residence times. The batch pretreatments of yellow poplar sawdust in the bench-scale digester were carried out at 210 and 230°C, 0.26% (w/w) sulfuric acid, and 1-, 3-, and 4-min residence times. The dilute acid prehydrolysis solubilized more than 90% of the hemicellulose, and increased the enzymatic digestibility of the cellulose that remained in the solids. Compositional analysis of the pretreated solids and liquors and mass balance data show that the two pretreatment devices had similar pretreatment performance.     

Combined surgical medialization and nerve-muscle pedicle reinnervation for unilateral vocal fold paralysis: Improved functional results and prevention of long-term deterioration of voice

Including those patients that were the subject of our previous report in 1990 (1) a total of 52 patients with unilateral vocal fold paralysis have been managed by combined surgical medialization and nerve-muscle pedicle reinnervation. The technique has been modified only slightly since 1985, when the first such surgery was performed. Short- and long-term voice results determined by a panel of sophisticated listeners are reported, as well as details of patient selection and complications. Better functional results were noted than were observed with surgical medialization alone, and long-term deterioration of the voice improvement initially achieved was prevented with this technique.