Application of plutonium radiochronometry to the analysis of plutonium age dating reference materials

Journal of Radioanalytical and Nuclear Chemistry - Radiochronometry is an important tool for nuclear forensic analysis. Plutonium has a wide array of parent/progeny pairs that can be measured to...     

Nonenzymatic protocol for Pseudomonas aeruginosa DNA preparation and rapid subtyping by mini pulsed-field gel electrophoresis.

The fastest protocol for Pseudomonas aeruginosa subtyping by contour clamped homogeneous electric field (CHEF) electrophoresis takes around 20 h. It includes enzymatic sample preparation, DNA restriction and fragment separation. Here, P. aeruginosa cells embedded in agarose miniplugs were lysed and deproteinized by incubating the miniplugs for 30 min in a single nonenzymatic solution. DNA molecules were digested for 2 h with 5 U of XbaI, and fragments were separated in 4.96 h by miniCHEF electrophoresis at 10 V/cm. Total time for P. aeruginosa subtyping was 8 h. Control experiments included DNA preparation by enzymatic or nonenzymatic protocols, different times of DNA restriction and comparisons of DNA separations done by miniCHEF or CHEF electrophoresis. Both methods and chambers gave similar results, but the rapid nonenzymatic method and the miniCHEF gave them in less time. Cells grown in broth or on plates were useful for nonenzymatic DNA preparation. Thirteen P. aeruginosa isolates were successfully fingerprinted using the protocol described here.     

Bioinspired Design Provides High‐Strength Benzoxazine Structural Adhesives

A synthetic strategy to incorporate catechol functional groups into benzoxazine thermoset monomers was developed, leading to a family of bioinspired small‐molecule resins and main‐chain polybenzoxazines derived from biologically available phenols. Lap‐shear adhesive testing revealed a polybenzoxazine derivative with greater than 5 times improved shear strength on aluminum substrates compared to a widely studied commercial benzoxazine resin. Derivative synthesis identified the catechol moiety as an important design feature in the adhesive performance and curing behavior of this bioinspired thermoset. Favorable mechanical properties comparable to commercial resin were maintained, and glass transition temperature and char yield under nitrogen were improved. Blending of monomers with bioinspired main‐chain polybenzoxazine derivatives provided formulations with enhanced shear adhesive strengths up to 16 MPa, while alloying with commercial core–shell particle‐toughened epoxy resins led to shear strengths exceeding 20 MPa. These results highlight the utility of bioinspired design and the use of biomolecules in the preparation of high‐performance thermoset resins and adhesives with potential utility in transportation and aerospace industries and applications in advanced composites synthesis.     

Variable temperature photoelectron spectroscopy. The adiabatic ionization potential of the iodine molecule

Vibrational structure is resolved in the first two bands in the Ne I photoelectron spectrum of iodine. The adiabatic IP is established by temperature variation, and spectroscopic IP for both bands are found to correspond to production of ions with three vibrational quanta. A photoionization value for the first IP corresponds to ions with two vibrational quanta. Structure is also observed in the corresponding bands of iodine bromide.     

Static and Dynamic Distortions in Five-Coordinate Complexes of cobalt(II) and rhodium(I)

Five-coordinate complexes have been prepared, of the general formulae [CoX(L'L₃)]⁺ and [RhX(L'L₃)], where X = halogen and L'L₃ = a quadridentate tripod-like ligand containing various Group V donor atom sets. The electronic spectra and magnetism of the cobalt(II) series can be interpreted on the basis of a low-spin d⁷-ion in a trigonal bipyramidal environment distorted by a static Jahn-Teller effect. Electronic spectral data for the trigonal bipyramidal rhodium(I) series show that the low-energy ¹A → ¹E ligand field transition is split at room temperature, but that the splitting collapses on reducing the temperature. This behaviour has been attributed to the operation of a dynamic Jahn-Teller effect.     

Improving Quantitative Measurements for the Evaporative Light Scattering Detector

A study was undertaken to evaluate a generic calibration routine for the evaporative light scattering detector (ELSD). The calibration routine was designed for use with gradient HPLC-ELSD in order to adjust for the effects of the non-linear response curve and the variation in response with mobile phase composition. A single calibrant was employed with an automated injection protocol to enable rapid capture of the calibration information. The study assessed the validity of the calibration method and the suitability of the calibrant for the quantitation and purity estimation of a series of structurally unrelated compounds. The calibration routine was demonstrated to improve the quality of quantitative estimates and purity estimates given by the gradient HPLC-ELSD. The average error in quantitation for the series of materials was 8.3%.