The mass spectra of some corticosteroid boronates

The mass spectra of methyl, n-butyl, t-butyl, phenyl and cyclohexyl boronates of various classes of steroid are reported and discussed. Steroid types represented are 17α, 21-dihydroxy-20-ketones, 17α, 20, 21-triols, 17α, 20-diols, 20, 21-ketols. Each gives rise to characteristic fragmentation modes, although derivatives of the 20α- and 20β-hydroxy compounds have similar spectra.     

A 119mSn Mössbauer study of the degradation of organotin stabilised PVC by gamma-irradiation

The technique of ^119mSn Mössbauer spectroscopy has been used to study the changes which occur in three organotin stabilisers within a PVC matrix when exposed to doses of γ-irradiation up to 20 Mrad. The stabilisers studied were dioctyltinbis(iso-octylthioglycollate) [Oct₂Sn(IOTG)₂], dibutyltinbis(iso-octylthioglycollate) [Bu₂Sn(IOTG)₂] and dibutyltinbis(iso-octylmaleate) [Bu₂Sn(IOM)₂] incorporated into the PVC at the appropriate commercial level by conventional hot milling techniques or solvent casting. Extended doses up to 20 Mrad showed that the final degradation product for all three stabilisers is SnCl₄ and that the rate of degradation depends not only upon the type of stabiliser but also upon the extent of thermo-mechanical damage suffered by the PVC during processing. Mössbauer spectra were recorded at intermediate doses in the range 0·1 to 10 Mrad and yielded complex spectra containing unresolved lines corresponding to mixtures of original stabilisers and degradation products. Intermediate degradation products are proposed and rapid conversion to SnCl₄ is observed to start at doses greater than 3 Mrad.     

Excitation spectrum of helium II: A series representation

A series representation is described which has pressure dependent phonon dispersion, and which is consistent with neutron scattering and calorimetric data.     

Influence of a water rinse on the structure and properties of poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) films

Poly(3,4-ethylene dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) films exhibit a complex structure of interconnected conductive PEDOT domains in an insulating PSS matrix that controls their electrical properties. This structure is modified by a water rinse, which removes PSS with negligible PEDOT loss. Upon PSS removal, film thickness is reduced by 35%, conductivity is increased by 50%, and a prominent dielectric relaxation is eliminated. These results suggest that the removed PSS is not associated with PEDOT and that the conductive domain network is not substantially altered by the removal of a significant fraction of insulator. The removal of PSS may benefit organic light emitting diode fabrication by reducing acid attack on indium tin oxide electrodes and lead to more robust performance in switching circuits by extending the working frequency range.