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J. T. Elliston S. E. Glover R. H. Filby 《Journal of Radioanalytical and Nuclear Chemistry》2005,263(2):301-306
Summary In the analysis of biological samples with sub ng/g uranium concentrations, pre-concentration has been shown to improve the detection limit for the determination of uranium. Recovery corrected kinetic phosphorescence analysis (KPA) combines pre-concentration and separation of uranium by anion-exchange from human tissues dissolved in 6M HCl, with the radiochemical yield determined by alpha-spectrometry, using 232U as a tracer. Total uranium is determined by KPA after correction for chemical recovery. Twenty-one randomly selected dissolved tissue samples from the United States Transuranium and Uranium Registries (USTUR) Case 0242 were chosen for comparative analyses. The set of samples included dissolved bone and soft tissues. Uranium concentrations for seven of the samples had not been previously reported. Direct KPA could not be used to determine uranium concentrations of five unreported tissues. Three of these tissues had uranium concentrations at or below the KPA LQ value of 0.028 ng/ml and two tissues had known matrix interferences. All seven of the unreported tissues were successfully analyzed by recovery corrected KPA; concentrations ranged from 9 to 1380 ng per tissue, including those that could not be analyzed by direct KPA due to matrix problems. Recovery corrected KPA gives results similar to direct KPA where matrix interferences and low detection limits are not encountered. A comparison of the direct method of KPA versus recovery corrected KPA shows marked improvement for the determination of uranium in samples that heretofore either uranium was not detected or the sample had to be drastically diluted to minimize matrix effects in order to measure uranium. 相似文献
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P.R. Elliston F. Habbal N. Saleh G.E. Watson K.W. Blazey H. Rohrer 《Journal of Physics and Chemistry of Solids》1975,36(9):877-881
Magnetic and optical measurements in the layer compound NaCrO2 are reported. This compound is antiferromagnetic with Tn = 46±2 K and θ = ?400±30 K. Broad antiferromagnetic resonances are observed which cannot be interpreted on any simple model. Optical absorption data are consistent with the appearance of antiferromagnetism. Non-intrinsic fluorescence has also been observed. 相似文献
3.
T. Mitchell P. Sandwall B. Rolfes M. Lobaugh J. Bowen J. Elliston S. E. Glover H. B. Spitz 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(1):223-225
A study was initiated to investigate the chronological deposition of uranium in certain species of trees growing on the site
of a former uranium metal processing facility. The Feed Materials Production Center (FMPC) is located in Fernald, Ohio, and
for roughly 40 years operated as a large scale uranium processing center. Core samples from several species of trees growing
in different locations throughout the site were extracted using a 12.5 mm incremental wood boring drill bit. After extraction,
each core sample was cut and packaged into individual sections representing 4 annual growth rings and submitted for instrumental
neutron activation analysis (INAA). The reaction 235U(n,f)140Ba→140La+γ was evaluated using high resolution germanium gamma-spectroscopy to detect the 1.596 MeV photon emission from the fission
product 140La following a minimum of a 3 week decay. A total of 106 samples representing 7 individual trees of 3 unique species were
irradiated. In addition to the tree-core samples, 18 quality control (QC) samples and 18 standard reference material (SRM)
Fly Ash samples were irradiated with the core samples for determining neutron flux. The activity in any one sample in a batch
was determined by comparison with the amount of natural uranium in the QC standards. No significantly measurable amount of
uranium was detected in any of the tree core samples, although 3 tree core samples were in excess of the minimum detectable
amount (30 ng). 相似文献
4.
R. F. Payne S. B. Clark J. T. Elliston 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(1):269-274
The simultaneous determination of multiple actinide isotopes in samples where total quantity is limited can sometimes present
a unique challenge for radioanalytical chemists. In this study, re-determination of 238Pu, 239+240Pu, and 241Am for soils collected and analyzed approximately three decades ago was the goal, along with direct determination of 241Pu. The soils had been collected in the early 1970’s from a shallow land burial site for radioactive wastes called the Subsurface
Disposal Area (SDA) at the Idaho National Lab (INL), analyzed for 238Pu, 239+240Pu, and 241Am, and any remaining soils after analysis had been archived and stored. We designed an approach to reanalyze the 238Pu, 239+240Pu, and 241Am and determine for the first time 241Pu using a combination of traditional and new radioanalytical methodologies. The methods used are described, along with estimates
of the limits of detection for gamma-and alpha-spectrometry, and liquid scintillation counting. Comparison of our results
to the earlier work documents the ingrowth of 241Am from 241Pu, and demonstrates that the total amount of 241Am activity in these soil samples is greater than would be expected due to ingrowth from 241Pu decay. 相似文献
5.
P.R. Elliston 《Journal of Physics and Chemistry of Solids》1977,38(2):179-181
Antiferromagnetic resonance measurements in rhombohedral NaCrS2 (TN = 17 K) are reported. The data are compared with theory developed by Battles for a collinear easy-plane antiferromagnet with anisotropy in the basal plane. While there is reasonable agreement with this theory, some discrepancies occur. These are presumably related to low-temperature in-plane distortions from hexagonal symmetry, previously postulated by other workers. 相似文献
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Eveleigh D. E. Bok J. D. El-Dorry H. El-Gogary S. Elliston K. Goyal A. Waldron C. Wright R. Wu Y. -M. 《Applied biochemistry and biotechnology》1995,51(1):169-177
Applied Biochemistry and Biotechnology - Cellulose, the world's most abundant organic material, is central to the world's ecosystem. This energy resource is mobilized and recycled by... 相似文献
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J. T. Elliston S. E. Glover R. H. Filby 《Journal of Radioanalytical and Nuclear Chemistry》2001,248(2):487-491
Two typical methods used for the determination of uranium in human autopsy tissues are kinetic phosphorescence analysis (KPA) and alpha-spectrometry, both of which have significant limitations and advantages. KPA is limited because of the amount of sample used (1–10 ml for sample digestion followed by one ml KPA aliquots), no isotopic information is provided, phosphorescence degradation by salts in solution, and even more importantly, it does not provide chemical recovery information. For samples with sub ng uranium concentrations per g of inorganic material, preconcentration is necessary, which may require chemical recovery (other than simple evaporation). While alpha-spectrometry has very good radiometric detection limits for 238U, the very long half-life of 238U (4.468·109 y) restricts its mass detection limit (27 ng). KPA, on the other hand, has a detection limit three orders of magnitude lower (0.02 ng) for natural uranium. A recovery corrected method for the determination of natural uranium in human tissues was developed combining preconcentration of human tissues dissolved in 6M HCl by anion exchange with alpha-spectrometry and kinetic phosphorescence analysis, utilizing 232U as a tracer. Solution aliquots containing up to 6 g of bone ash were pre-concentrated for KPA measurement thereby allowing the use of up to 25% of the original sample solution weight for analysis by KPA. The radiochemical yield of 232U was determined by alpha-spectrometry and the uranium content was determined by KPA. The mean radiochemical yields obtained for human tissue samples range from 65% to 106% with a mean of 85%±8%. 相似文献
8.
J. L. Gels J. T. Elliston J. W. Talnagi S. E. Glover H. B. Spitz 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(1):217-221
A revized method for determining 232Th using a pre-concentration neutron activation analysis (PCNAA) procedure was developed to accommodate irradiation in a dry
irradiation tube environment. 232Th extracted by ion-exchange from a sample was electrodeposited onto 5/8″ diameter vanadium planchets, which are arranged
in a stack and irradiated in the dry tube central irradiation facility (CIF) of the reactor. The higher neutron fluence of
this facility improved sensitivity by approximately 37%, however, the higher temperatures required modifications to the irradiation
procedure. Because the heat in the CIF would melt the plastic spacers used in the original method, a tube of high-purity quartz
was used to contain samples, and high purity quartz spacers were used to separate the vanadium planchets during the irradiation.
Test irradiations have determined that no significant transfer occurred from the disks to the silica disks and no significant
variation in the neutron flux was observed. Finally, a thin film barrier was tested for its ability to reduce recoil contamination
from 229Th onto the detector during alpha spectroscopy. The film was shown to reduce contamination to levels indistinguishable from
normal background. 相似文献
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10.
Adam Elliston Samuel R. A. Collins Craig B. Faulds Ian N. Roberts Keith W. Waldron 《Applied biochemistry and biotechnology》2014,172(7):3621-3634
Waste copier paper is a potential substrate for the production of glucose relevant for manufacture of platform chemicals and intermediates, being composed of 51 % glucan. The yield and concentration of glucose arising from the enzymatic saccharification of solid ink-free copier paper as cellulosic substrate was studied using a range of commercial cellulase preparations. The results show that in all cellulase preparations examined, maximum hydrolysis was only achieved with the addition of beta-glucosidase, despite its presence in the enzyme mixtures. With the use of Accellerase® (cellulase), high substrate loading decreased conversion yield. However, this was overcome if the enzyme was added between 12.5 and 20 FPU g substrate?1. Furthermore, this reaction condition facilitated continual stirring and enabled sequential additions (up to 50 % w/v) of paper to be made to the hydrolysis reaction, degrading nearly all (99 %) of the cellulose fibres and increasing the final concentration of glucose whilst simultaneously making high substrate concentrations achievable. Under optimal conditions (50 °C, pH 5.0, 72 h), digestions facilitate the production of glucose to much improved concentrations of up to 1.33 mol l?1. 相似文献
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