Authors:Sherrod Maxwell, Brian Culligan, Angel Kelsey-Wall, and Patrick Shaw
A new rapid method for the determination of actinides in food samples has been developed at the Savannah River Site Environmental
Lab (Aiken, SC, USA) that can be used for emergency response or routine food samples. If a radiological dispersive device
or improvised nuclear device event occurs, there will be a urgent need for rapid analyzes of many different environmental
matrices, as well as food samples, to support dose mitigation and protect general populations from radioactivity that may
enter the food chain. The recent accident at Fukushima nuclear power plant in March, 2011 reinforces the need to have rapid
analyzes for radionuclides in environmental and food samples. The new method to determine actinides in food samples utilizes
a furnace ashing step, a rapid sodium hydroxide fusion method, a lanthanum fluoride matrix removal step, and a column separation
process with stacked TEVA, TRU, and DGA resin cartridges. The furnace ashing and rapid fusion steps are performed in relatively
inexpensive, reusable zirconium crucibles. Alpha emitters are prepared using rare earth micro precipitation for counting by
alpha spectrometry. The method showed high chemical recoveries and effective removal of interferences. The determination of
actinides in food samples can be performed in less than 8 h for 10 g samples with excellent quality for emergency samples
using short count times. Larger food samples (100 g) may be processed in 24 h or less. The rapid fusion technique is a rugged
sample digestion method that ensures that any refractory actinide particles are effectively digested. This method can be used
to meet the derived intervention level guidelines recommended by the U.S. Food and Drug Administrations.
Authors:Carmen Rodríguez-Tenreiro, Carmen Alvarez-Lorenzo, Ángel Concheiro, and J. Torres-Labandeira
The interactions between Carbopol and β-cyclodextrin (BCD) or hydroxypropyl-β-cyclodextrin (HPBCD) were studied by differential
scanning calorimetry (DSC) and FTIR spectroscopy. Aqueous solutions of both components were desiccated by freeze-drying or
heating in an oven (films) at various temperatures. The use of different drying procedures allowed their influence on the
interactions to be studied. The evolution of the Carbopol glass-transition was also evaluated by DSC using first heating runs
up to different temperatures. Disappearance of the Carbopol glass-transition was observed in the freeze-dried systems prepared
with either of the cyclodextrins and in the films that contained HPBCD. The changes in the FTIR band of Carbopol at 1700 cm-1 confirmed the existence of interactions with both cyclodextrins, especially with HPBCD. This information may be useful for
optimising the solubilizing capacity and controlled release performance of aqueous Carbopol-cyclodextrin systems.
Authors:M. Woodring, J. Ely, L. Angel, I. Wright, M. Eslinger, A. Pospical, and J. Ellis
Pacific Northwest National Laboratory (PNNL) has deployed a large array of radiation portal monitors for the Department of
Homeland Security and U.S. Customs and Border Protection. These portal monitors scan incoming vehicles crossing the U.S. border
and shipping containers leaving international ports for radioactive material via gamma-ray and neutron detection. Data produced
and captured by these systems are recorded for every vehicle related to radiation signature, sensor/system status, local background,
as well as a host of other variables. Within the Radiation Portal Monitor Project at PNNL, state-of-health observation and
analysis for the whole RPM array using these data to determine functionality and performance is ongoing. Advanced state-of-health
analysis and monitoring algorithms are being developed. Preparations are underway to incorporate the more difficult state-of-health
monitoring of the mobile RPM and Advanced Spectroscopic Portals.
Authors:K. Bower, A. Angel, R. Gibson, T. Robinson, D. Knobeloch, and B. Smith
Advances in liquid scintillation counting (LSC) technologies, such as imporved scintillation cocktail formulations and alpha-beta radiation discrimination, make LSC suitable for applications in uranium process chemistry. Ease of use, low cost, and the huge dynamic range of LSC are distinct advantages for analytical support of actinide processing. All uranium isotopes decay primarily with alpha radiation emission. The immediate short-lived daughters of238U are234Th and234Pa. These nuclides are beta emitters having energy bands that overlap the uranium bands in a liquid scintillation spectrum. The resolution of these overlapping bands by alpha-beta radiation discrimination is useful for uranium quantification and purity verification. Protactinium-234 is a high-energy beta emitter that can be further identified and quantified from it's Cherenkov radiation. Energy spectra were collected on the Packard 2500AB liquid scintillator analyzer for uranyl solutions in diisopropylnaphthalene and pseudocumene based scintillator cocktails. Calibration curves were prepared for nitric, hydrochloric, and sulfuric acid media. Base titrations demonstrated the effect of acid quenching on those system. Ion exchange and water soluble polymer extraction studies are readily followed using liquid scintillation methods.
Authors:Brecht Egle, Juan Muñoz, Nerea Alonso, Wim De Borggraeve, Antonio de la Hoz, Angel Díaz-Ortiz, and Jesús Alcázar
The first example of an alkyl–aryl Negishi coupling in a practical, sustainable, and high-yielding process using a silica-supported catalyst in flow is described. Excellent conversions and good functional group compatibility were obtained under very mild conditions. Functionalized alkyl groups were also introduced to provide access to synthetically useful molecules and to demonstrate the versatility of the method. The scalability was assessed, and a throughput of 7.5 mmol/h of processed substrate was achieved. All crude products were free from phosphine derivatives and ready for use in subsequent reaction steps.
Authors:Valeria Palermo, Ángel G. Sathicq, Patricia G. Vázquez, Horacio J. Thomas, and Gustavo P. Romanelli
In this research, we report the preparation of doped PMo Keggin heteropolyacids where Mo is partially replaced by V, Bi, and Bi–V. These catalysts were characterized by means of ICP-AES analysis, 31P-NMR, UV–visible spectra, FT-IR spectra, thermal analysis, and textural properties. In addition, the activities of the synthesized catalysts were evaluated in the selective oxidation of sulfides to sulfoxides/sulfones. The incorporation of V, Bi and Bi–V into the structure of H3PMo12O40 increases the catalytic activity. The two most active catalysts, those with V and V–Bi were supported on aminopropyl-functionalized silica (SiO2NH2) and they were found to be and efficient heterogeneous catalysts for the selective oxidation of diphenylsulfide to the corresponding sulfoxide/sulfone.
Authors:Nerea Alonso, M. Muñoz Juan de, Brecht Egle, Johannes L. Vrijdag, Wim M. De Borggraeve, Antonio de la Hoz, Angel Díaz-Ortiz, and Jesús Alcázar
The first continuous flow carbonylation reaction using aryl formates as CO precursor is reported. The reaction is practical, scalable and high yielding. The use of a flow protocol safely allows expanding the scope to activated chlorides, nitrogen heterocycles and to the selective introduction of an ester group in dihalo-derivatives. Further selective reduction of the ester formed to an aldehyde in flow is also described.