In the present work, an analytical method has been developed for the determination of the amount of man-made beryllium metal and/or beryllium compounds in soil in addition to the amount of native ...beryllium that is present. The method is based on the premise that if high-fired beryllium oxide can be extracted efficiently, then beryllium metal and acid-soluble beryllium salts would also be extracted efficiently.
The proposed method involves the addition of 9 mL of an aqueous solution of 5% (wt/vol) ammonium bifluoride (ABF) to a 10-mL tube with 250 mg of dried, sieved soil. The tube is placed in a convection oven at 70 ᵒC and is mechanically rocked for 60 min to mix the sample while it is being heated. Beryllium oxide, beryllium metal and beryllium salts would include virtually all of the anthropogenic (man-made) beryllium compounds that might contaminate soil. Compounds that may be naturally present in soil, such as beryllium silicates and beryllium aluminosilicates, are not extracted efficiently by ABF solution under these conditions. As a second step after the initial extraction of the sample of soil with ABF solution, the soil is completely dissolved in a mixture of strong acids and that acid solution is then analyzed to determine the residual beryllium.
The ratio of the extractable to residual beryllium in the same aliquot of native soil can be measured for a soil type in a local region and then used to calculate the amount of anthropogenic beryllium in soil. Therefore, the method may have application in the measurement of beryllium-contaminated soil at sites where beryllium oxide, beryllium metal and/or beryllium salts may have been used.
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•Beryllium was partially extracted from soil with ammonium-bifluoride solution.•Soils samples with solution were rocked while they were heated in an oven.•R is the ratio of extracted beryllium to residual beryllium in native soil.•Anthropogenic beryllium is calculated with R from extracted and residual beryllium.
The analytical characteristics of U isotopic analysis with laser-induced breakdown spectroscopy (LIBS) were investigated by analyzing a series of U3O8–Li2B4O7 fused glassy disks. The 235U isotopic ...contents in the samples ranged from natural abundance at ~0.72 atom-% to a highly enriched level at ~94 atom-%. Isotopic information of the sample was extracted from the LIBS spectra through multivariate nonlinear spectral fitting, which is theoretical in basis and does not require calibration with isotopically enriched standards. A database consisting of twelve U-line pairs, which can be used for multiple-line-pair spectral fitting, was constructed for the spectral region from 424.300 to 424.500 nm. The use of twelve line pairs in the fitting was found to offer superior performance than the use of only a single line pair (424.412 nm for 235U and 424.437 nm for 238U). The analytical accuracies (biases) in absolute 235U / (235U + 238U) ratios were about ±4% for the single-line-pair fitting, and improved to around ±1% for the multiple-line-pair fitting. In both cases, precisions, expressed as standard deviations from ten repetitive measurements, each with an accumulation of LIBS signals from 100 laser shots, were found to be similar and within 0.2% in absolute 235U / (235U + 238U) ratios. Although hyperfine structure and Stark broadening can be incorporated into the algorithm as fitting parameters, the inclusion of these two effects caused overfitting, which degraded analytical accuracies. The best multiple-line-pair fitting algorithm was found to be the one with the least fitting parameters i.e., one global linewidth (namely, neglecting Stark broadening) and without inclusion of hyperfine structure, which consequently mandates a detector delay time sufficiently long so that almost all the Stark effect subsides.
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•Performed uranium isotopic analysis with atmospheric-pressure LIBS•U-235 content range from natural (0.72%) to highly enriched level (~94%)•Isotopic analysis performed with spectral fitting (requires no calibration standard)•Compared several fitting algorithms to extract isotopic information from LIBS spectra
In the present work, an analytical method has been developed for the determination of the amount of man-made beryllium metal and/or beryllium compounds in soil in addition to the amount of native ...beryllium that is present. The method is based on the premise that if high-fired beryllium oxide can be extracted efficiently, then beryllium metal and acid-soluble beryllium salts would also be extracted efficiently.
The unique properties associated with beryllium metal ensures the continued use in many industries despite the documented health and environmental risks. While engineered safeguards and personal ...protective equipment can reduce risks associated with working with the metal, it has been mandated by the Environmental Protection Agency (EPA) and Occupational Safety and Health Administration (OSHA) that the workplace air and surfaces must be monitored for toxic levels. While many methods have been developed to monitor levels down to the low μg/m3, the complexity and expense of these methods have driven the investigation into alternate methodologies. Herein, we use a combination of the previously developed fluorescence Be(II) ion detection reagent, 10-hydroxybenzohquinoline (HBQ), with an optical field enhanced silicon nanopillar array, creating a new surface immobilized (si-HBQ) platform. The si-HBQ platform allows the positive control of the reagent for demonstrated reusability and a pillar diameter based tunable enhancement. Furthermore, native silicon nanopillars are overcoated with thin layers of porous silicon oxide to develop an analytical platform capable of a 0.0006 μg/L limit of detection (LOD) using sub-μL sample volumes. Additionally, we demonstrate a method to multiplex the introduction of the sample to the platform, with minimal 5.2% relative standard deviation (RSD) at 0.1 μg/L, to accommodate the potentially large number of samples needed to maintain industrial compliance. The minimal sample and reagent volumes and lack of complex and highly specific instrumentation, as well as positive control and reusability of traditionally consumable reagents, create a platform that is accessible and economically advantageous.
Genomic imprinting, representing parent-specific expression of alleles at a locus, raises many questions about how--and especially why--epigenetic silencing of mammalian genes evolved. We present the ...first in-depth study of how a human imprinted domain evolved, analyzing a domain containing several imprinted genes that are involved in human disease. Using comparisons of orthologous genes in humans, marsupials, and the platypus, we discovered that the Prader-Willi/Angelman syndrome region on human Chromosome 15q was assembled only recently (105-180 million years ago). This imprinted domain arose after a region bearing UBE3A (Angelman syndrome) fused with an unlinked region bearing SNRPN (Prader-Willi syndrome), which had duplicated from the non-imprinted SNRPB/B'. This region independently acquired several retroposed gene copies and arrays of small nucleolar RNAs from different parts of the genome. In their original configurations, SNRPN and UBE3A are expressed from both alleles, implying that acquisition of imprinting occurred after their rearrangement and required the evolution of a control locus. Thus, the evolution of imprinting in viviparous mammals is ongoing.
Chemical processes involved in the development of latent fingerprints using the cyanoacrylate fuming method have been studied. Two major types of latent prints have been investigated-clean and oily ...prints. Scanning electron microscopy (SEM) has been used as a tool for determining the morphology of the polymer developed separately on clean and oily prints after cyanoacrylate fuming. A correlation between the chemical composition of an aged latent fingerprint, prior to development, and the quality of a developed fingerprint has been observed in the morphology. The moisture in the print prior to fuming has been found to be more important than the moisture in the air during fuming for the development of a useful latent print. In addition, the amount of time required to develop a high quality latent print has been found to be within 2 min. The cyanoacrylate polymerization process is extremely rapid. When heat is used to accelerate the fuming process, typically a period of 2 min is required to develop the print. The optimum development time depends upon the concentration of cyanoacrylate vapors within the enclosure.
Melanotic neuroectodermal tumor of infancy is a rare condition that typically presents within the first 6 months of life. It rarely metastasizes but is locally aggressive. Melanotic neuroectodermal ...tumor of infancy has been reported under several other names including retinal anlage tumor and melanotic progonoma. Most commonly, melanotic neuroectodermal tumor of infancy originates in the maxilla.1-3 Tumors in previously reported orbital cases have arisen from adjacent structures or from orbital bone.4-6 Recommended treatment of melanotic neuroectodermal tumor of infancy has consisted of complete excision with wide tissue margins, although success has been reported after incomplete resection. For those patients in whom surgical resection is not possible, various chemotherapy approaches have been reported with mixed results ranging from failure to sustained tumor regression.2,8,9 We report a case of orbital melanotic neuroectodermal tumor of infancy adherent to sclera and successfully treated with chemotherapy and subtotal excision.
The current interest in returning to the Moon and Mars by 2030 makes cost effective and low mass health monitoring sensors essential for spacecraft development. In space, there are many surface ...measurements that are required to monitor the condition of the spacecraft including: surface temperature, radiation dose, and impact. Through the use of phosphors, these conditions can be monitored. Practical space-based phosphor sensors will depend heavily upon research investigating the resistance of phosphors to ionizing radiation and the ability to anneal or self-heal from damage caused by ionizing radiation. The cathodoluminescence (CL) testing was performed using the low energy electron system located at the NASA Marshall Space Flight Center (MSFC) in Huntsville, Alabama. For the materials tested, several interesting results were observed. For most materials, increases in both beam energy and current density improved the CL fluorescence yield. It was also noted that YAG:Nd,Ce has the greatest near infrared intensity for any of the tested materials. The evaluation of dopant concentration in YPO 4 :Nd showed minimal differences in spectral shape and intensity. While the total electron dose was small, the intention was to maximize the number of irradiated materials
Perfluoroalkyl substances were determined in liver tissues and blood of polar bears (Ursus maritimus) from five locations in the North American Arctic and two locations in the European Arctic. ...Concentrations of perfluorooctane sulfonate (PFOS), perfluorohexane sulfonate, heptadecafluorooctane sulfonamide, and perfluoroalkyl carboxylates with C8−C15 perfluorinated carbon chains were determined using liquid chromatography tandem mass spectrometry. PFOS concentrations were significantly correlated with age at four of seven sampling locations, while gender was not correlated to concentration for any compound measured. Populations in South Hudson Bay (2000−2730 ng/g wet wt), East Greenland (911−2140 ng/g wet wt), and Svalbard (756−1290 ng/g wet wt) had significantly (P < 0.05) higher PFOS concentrations than western populations such as the Chukchi Sea (435−729 ng/g wet wt). Concentrations of perfluorocarboxylic acids (PFCAs) with adjacent chain lengths (i.e., C9:C10 and C10:C11) were significantly correlated (P < 0.05), suggesting PFCAs have a common source within a location, but there were differences in proportions of PFCAs between eastern and western location sources. Concentrations of PFOS in liver tissue at five locations were correlated with concentrations of four polychlorinated biphenyl congeners (180, 153, 138, and 99) in adipose tissue of bears in the same populations, suggesting similar transport pathways and source regions of PFOS or precursors.
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