A new bomb-combustion system for tritium extraction.

Quantitative extraction of tritium from a sample matrix is critical to efficient measurement of the low-energy pure beta emitter. Oxidative pyrolysis using a tube furnace (Pyrolyser) has been adopted as an industry standard approach for the liberation of tritium (Warwick et al. in Anal Chim Acta 676:93-102, 2010) however pyrolysis of organic-rich materials can be problematic. Practically, the mass of organic rich sample combusted is typically limited to <1 g to minimise the possibility of incomplete combustion. This can have an impact on both the limit of detection that can be achieved and how representative the subsample is of the bulk material, particularly in the case of heterogeneous soft waste. Raddec International Ltd (Southampton, UK), in conjunction with GAU-Radioanalytical, has developed a new high-capacity oxygen combustion bomb (the Hyperbaric Oxidiser; HBO2) to address this challenge. The system is capable of quantitatively combusting samples of 20-30 g under an excess of oxygen, facilitating rapid extraction of total tritium from a wide range sample types.

A study on the levels of radioactivity in fish samples from the experimental lakes area in Ontario, Canada.

To better understand background radiation levels in country foods, a total of 125 fish samples were collected from three lakes (Lake 226, Lake 302 and Lake 305) in the Experimental Lakes Area (ELA) in Ontario of Canada during the summer of 2014. Concentrations of naturally occurring radionuclides ((226)Ra, (210)Pb and (210)Po) as well as anthropogenic radionuclides ((134)Cs and (137)Cs) were measured. This study confirmed that (210)Po is the dominant contributor to radiation doses resulting from fish consumption. While concentrations of (210)Pb and (226)Ra were below conventional detection limits, (210)Po was measured in almost all fish samples collected from the ELA. The average concentration was about 1.5 Bq/kg fresh weight (fw). None of the fish samples analysed in this study contained any detectable levels of (134)Cs. An average (137)Cs level of 6.1 Bq/kg fw was observed in freshwater fishes harvested in the ELA, almost twice that of samples measured in the National Capital Region of Canada in 2014 and more than 20 times higher than the levels observed in marine fish harvested from the Canadian west coast in 2013 and 2014. However, it is important to note that the concentrations of (137)Cs in fish samples from these inland lakes are considered very low from a radiological protection perspective. The resulting radiation dose for people from fish consumption would be a very small fraction of the annual dose from exposure to natural background radiation in Canada. The results indicate that fishes from inland lakes do not pose a radiological health concern.

Antibody light chain variable domains and their biophysically improved versions for human immunotherapy.

We set out to gain deeper insight into the potential of antibody light chain variable domains (VLs) as immunotherapeutics. To this end, we generated a naïve human VL phage display library and, by using a method previously shown to select for non-aggregating antibody heavy chain variable domains (VHs), we isolated a diversity of VL domains by panning the library against B cell super-antigen protein L. Eight domains representing different germline origins were shown to be non-aggregating at concentrations as high as 450 µM, indicating VL repertoires are a rich source of non-aggregating domains. In addition, the VLs demonstrated high expression yields in E. coli, protein L binding and high reversibility of thermal unfolding. A side-by-side comparison with a set of non-aggregating human VHs revealed that the VLs had similar overall profiles with respect to melting temperature (T(m)), reversibility of thermal unfolding and resistance to gastrointestinal proteases. Successful engineering of a non-canonical disulfide linkage in the core of VLs did not compromise the non-aggregation state or protein L binding properties. Furthermore, the introduced disulfide bond significantly increased their T(m)s, by 5.5-17.5 ° C, and pepsin resistance, although it somewhat reduced expression yields and subtly changed the structure of VLs. Human VLs and engineered versions may make suitable therapeutics due to their desirable biophysical features. The disulfide linkage-engineered VLs may be the preferred therapeutic format because of their higher stability, especially for oral therapy applications that necessitate high resistance to the stomach's acidic pH and pepsin.

Results and lessons learned from radiological/nuclear emergency response exercise held in Québec, Canada.

The Ministry of Sustainable Development, Environment and Parks of Québec (Ministère du Développement durable, de l'Environnement et des Parcs du Québec-MDDEP) held a 3-d provincial nuclear emergency response exercise in September 2008 that saw participation from Canadian provincial and federal departments. Nuclear emergency exercises are regularly held in Québec, given the presence of the Gentilly-2 nuclear power plant situated in Bécancour on the St. Lawrence River. The significance of this exercise is that it marks the first exercise held in Canada where environmental samples spiked with relevant radioisotopes were analyzed during the exercise, both on-site and remotely, and where the results of those analyses had a direct impact on the decisions made during the exercise. Following the exercise, samples were sent to two other laboratories that are part of the Canadian National Nuclear Laboratory Network for analysis, providing the first intercomparison exercise for the Network. The results of the analysis of the air and drinking water samples, as well as the lessons learned during the exercise, are presented and discussed in this article.

Radiostrontium and radium analysis in low-level environmental samples following a multi-stage semi-automated chromatographic sequential separation.

Strontium isotopes, (89)Sr and (90)Sr, and (226)Ra being radiotoxic when ingested, are routinely monitored in milk and drinking water samples collected from different regions in Canada. In order to monitor environmental levels of activity, a novel semi-automated sensitive method has been developed at the Radiation Protection Bureau of Health Canada (Ottawa, Canada). This method allows the separation and quantification of both (89)Sr and (90)Sr and has also been adapted to quantify (226)Ra during the same sample preparation procedure. The method uses a 2-stage purification process during which matrix constituents, such as magnesium and calcium that are rich in milk, are removed as well as the main beta-interferences (e.g., (40)K, (87)Rb, (134)Cs, (137)Cs, and (140)Ba). The first purification step uses strong cation exchange (SCX) chromatography with commercially available resins. In a second step, fractions containing the radiostrontium analytes are further purified using high-performance ion chromatography (HPIC). While (89)Sr is quantified by Cerenkov counting immediately after the second purification stage, the same vial is counted again after a latent period of 10-14 days to quantify the (90)Sr activity based on (90)Y ingrowth. Similarly, the activity of (226)Ra, which is separated by SCX only, is determined via the emanation of (222)Rn in a 2-phase aqueous/cocktail system using liquid scintillation counting. The minimum detectable concentration (MDC) for (89)Sr and (90)Sr for a 200 min count time at 95% confidence interval is 0.03 and 0.02 Bq/L, respectively. The MDC for (226)Ra for a 100 min count time is 0.002 Bq/L. Semi-annual intercomparison samples from the USA Department of Energy Mixed Analyte Performance Evaluation Program (MAPEP) were used to validate the method for (89)Sr and (90)Sr. Spiked water samples prepared in-house and from International Atomic Energy Agency (IAEA) were used to validate the (226)Ra assay.

Method comparison for 241Am emergency urine bioassay.

241Am is one of the high-risk radionuclides that might be used in a terrorist attack. 241Am in urine bioassay can identify the contaminated individuals who need immediate medical intervention and decontamination. This paper compares three methods for the measurement of 241Am in urine, namely liquid scintillation counting (LSC), inductively coupled plasma mass spectrometry (ICP-MS) and gamma spectrometry (GS), at two levels, 20 and 2 Bq l(-1). All three methods satisfied the ANSI N13.30 radio-bioassay criteria for accuracy and repeatability. ICP-MS offered the best sensitivity and fastest sample turnaround; however, the ICP-MS system used in this work may not be available in many bioassay laboratories. LSC and GS are more commonly available instruments. GS requires minimal or no sample preparation, which makes it a good candidate method. Moreover, the sample throughput can be significantly improved if the GS and LSC methods are automated.