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Abstract  

It is a well-known result of Solecki that every nonlocally compact Polish group with a two-sided invariant metric contains continuum many pairwise disjoint sets which are Haar ambivalent. Inspired by a recent result of Zajíček, we give such an explicit and natural collection in the space of continuous functions on the interval. Our collection involves functions which have infinite derivatives and knot points.

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Abstract  

During the drainage of nuclear reactors for decommissioning or maintenance the activity is plated out on the steel surfaces can be a major dose burden to workers and has to be considered for final disposal. A simple model has been developed to correlate the kinetics of plate-out of radioactive materials on stainless steel surfaces at ambient temperature.

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Abstract  

The effects which an iron(III) based smoke suppressing compound have on the thermal stability of some acrylonitrile–butadiene–styrene/chlorinated poly(vinyl chloride) (ABS/CPVC) polymer blends have been investigated. Thermogravimetric analysis (TG) experiments have shown that there are three distinctive stages occurring during the thermal breakdown of these blends both when the iron compound is absent and present in the polymer formulations. The most important effect which the iron compound has when it is present in these blends is to modify the decomposition chemistry which takes place and the effect becomes more pronounced as the concentration of CPVC present in the blends increases. Other important effects are that the iron compound stabilises the blends so that mass loss is significantly reduced (by up to 50% in some cases) and the onset temperature of decomposition is raised. Flammability data generated during earlier work is supported by the TG results obtained in this work especially in the important area of smoke formation and suppression.

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Abstract  

Cross-linked polymers have particular rheological responses during reprocessing, e. g. if the material is recycled, special processing conditions are required. Other virgin polymers can be used as a blending component to enhance rheological properties. Bi-layer film of EVA/LLDPE was produced on a blown film line and cross-linked by high-energy radiation. This film was ‘agglomerated’ then reprocessed in a twin-screw extruder with virgin LLDPE and blown into film. The miscibility of the blend components was then studied using a TA Instruments temperature modulated differential scanning calorimeter (TMDSC). It was found that the cross-linked EVA/LLDPE scrap and the LLDPE have a slight miscibility in the liquid state. A bigger portion of LLDPE was miscible (dissolved) in EVA in low LLDPE blends. A positive deviation in the heat capacity of the LLDPE component compared to the additivity rule indicated melting to be more reversible in the first heating cycle. This initial miscibility was attributed to being induced by high shear during processing. A smaller positive deviation also occurred in the second heating cycle. This was attributed to intrinsic miscibility.

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Abstract  

The analysis of antimony in soil is an important component in the assessment of environmental risk associated with the discharge of munitions at small arms ranges. Proficiency testing samples associated with accreditation to the ISO 17025 standard have been examined for their antimony content using Instrument Neutron Activation Analysis (INAA) and using microwave assisted in situ hydrofluoric acid or nitric acid digestion, or nitrate ashing, followed by ICP-MS analysis. Data are compared with the proficiency testing criteria associated with accreditation and with consensus data. All three techniques afford data which are consistent with accredited analyses. However, the antimony concentrations obtained are method dependant, and generally as follows; INAA > in situ HF > nitrate ashing > nitric acid. In situ HF data and nitrate ashing data are systematically higher and lower than consensus values, respectively, but within the acceptable accreditation range. INAA is the only technique which affords a concentration for antimony in the certified reference material PACS-2 (10.0 ± 0.1 μg g−1) which is not statistically different from its certified value (11.3 ± 1.3 μg g−1).

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Abstract  

A cloud point extraction method followed by inductively coupled plasma-mass spectrometry (ICP-MS) has been developed for the detection of trivalent lanthanides (Ln(III)) in aqueous samples. Ammonium pyrrolodinedithiocarbamate (APDC) was used as the chelating ligand with 2 wt% Triton X-114 as the surfactant. Various experimental parameters were investigated and the extraction efficiency, distribution ratios and concentration factors for the extraction of lanthanum (La), neodymium (Nd), europium (Eu) and thulium (Tm) were determined.

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Similarity between seed bank and aboveground vegetation is frequently studied in order to better understand how community composition is affected by factors such as disturbance and succession. Grassland plant communities are known to be sensitive to shifts in precipitation and increases in temperature associated with climate change, but we do not know if and how these factors interact to affect the similarity between seed bank and aboveground vegetation. Also unknown is how the impact of grazing, the dominant land-use in grasslands, will interact with climatic conditions to affect similarity. We manipulated precipitation and temperature, and cut vegetation (as a proxy for grazing) at a grassland site for three years. Percent cover of aboveground vegetation was estimated in the third year, and compared with persistent seed bank samples taken in the year prior from the same plots. Similarity increased with reduced precipitation, was unresponsive to warming, and decreased with clipping. The aboveground community responded strongly to the treatments, while the seed bank community did less so, suggesting similarity responses were largely driven by changes in aboveground vegetation. Because of the importance of the seed bank in vegetation regeneration, understanding the relationship between seed bank and aboveground vegetation will improve our understanding of plant community dynamics under climate change and varied management (grazing) intensities.

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Abstract  

A high-level waste (HLW) remediation process scheduled to begin in 2007 at the Savannah River Site is the Modular Caustic Side Solvent Extraction (CSSX) Unit (MCU). The MCU will use a hydrocarbon solvent (diluent) containing a cesium extractant, a calix[4]arene compound, to extract radioactive cesium from caustic HLW. The resulting decontaminated HLW waste or raffinate will be processed into grout at the Saltstone Production Facility (SPF). The cesium containing CSSX stream will undergo washing with dilute nitric acid followed by stripping of the cesium nitrate into a very dilute nitric acid or the strip effluent stream and the CSSX solvent will be recycled. The Defense Waste Processing Facility (DWPF) will receive the strip effluent stream and immobilize the cesium into borosilicate glass. Excess CSSX solvent carryover from the MCU creates a potential flammability problem during DWPF processing. Bench-scale DWPF process testing was performed with simulated waste to determine the fate of the CSSX solvent components. A simple high performance liquid chromatography (HPLC) method was developed to identify the modifier (which is used to increase Cs extraction and extractant solubility) and extractant within the DWPF process. The diluent and triocytlamine (which is used to suppress impurity effect and ion-pair disassociation) were determined using gas chromatography mass spectroscopy (GCMS). To close the organic balance, two types of sample preparation methods were needed. One involved extracting aqueous samples with methylene chloride or hexane, and the second was capturing the off gas of the DWPF process using carbon tubes and rinsing the tubes with carbon disulfide for analysis. This paper addresses the development of the analytical methods and the bench-scale simulated waste study results.

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Summary Cold pressed linseed oil and paints prepared using the inorganic pigments; lead white and red lead, were characterized using non-isothermal differential scanning calorimetry (DSC) in an air atmosphere to determine the effect of the pigment on the oxidative polymerisation of the drying oil medium. For each paint sample, the onset temperature for oxidation was reduced from 166°C to the range 50 to 60°C when a heating rate of 5 K min-1 was used. In order to determine the rate of drying, the non-isothermal experiments were carried out using a range of heating rates. A change in the mechanism oxidative polymerization was observed as the heating rate was increased.

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Abstract  

The use of depleted uranium in military ordinance has led to an increasing need to determine isotope-specific uranium concentrations in environmental matrices. To this end, gamma-ray spectrometry, ICP-MS and INAA methods have been validated, in accordance with the ISO 17025 standard. Reporting limits of 0.21 (U-235) and 0.91 (U-238) ng/L were obtained by ICP-MS analysis of water. Higher reporting limits were obtained for INAA (U-238 only) validations of water and gamma-ray spectrometric validations of soil and water. Accredited methods have been used to determine uranium concentration and isotope ratio of samples obtained from the Defence Research and Development Canada Valcartier, Quebec.

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