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Sample records for bulk speciation methods

  1. Complementary arsenic speciation methods: A review

    Energy Technology Data Exchange (ETDEWEB)

    Nearing, Michelle M., E-mail: michelle.nearing@rmc.ca; Koch, Iris, E-mail: koch-i@rmc.ca; Reimer, Kenneth J., E-mail: reimer-k@rmc.ca

    2014-09-01

    The toxicity of arsenic greatly depends on its chemical form and oxidation state (speciation) and therefore accurate determination of arsenic speciation is a crucial step in understanding its chemistry and potential risk. High performance liquid chromatography with inductively coupled mass spectrometry (HPLC–ICP-MS) is the most common analysis used for arsenic speciation but it has two major limitations: it relies on an extraction step (usually from a solid sample) that can be incomplete or alter the arsenic compounds; and it provides no structural information, relying on matching sample peaks to standard peaks. The use of additional analytical methods in a complementary manner introduces the ability to address these disadvantages. The use of X-ray absorption spectroscopy (XAS) with HPLC–ICP-MS can be used to identify compounds not extracted for HPLC–ICP-MS and provide minimal processing steps for solid state analysis that may help preserve labile compounds such as those containing arsenic-sulfur bonds, which can degrade under chromatographic conditions. On the other hand, HPLC–ICP-MS is essential in confirming organoarsenic compounds with similar white line energies seen by using XAS, and identifying trace arsenic compounds that are too low to be detected by XAS. The complementary use of electrospray mass spectrometry (ESI–MS) with HPLC–ICP-MS provides confirmation of arsenic compounds identified during the HPLC–ICP-MS analysis, identification of unknown compounds observed during the HPLC–ICP-MS analysis and further resolves HPLC–ICP-MS by identifying co-eluting compounds. In the complementary use of HPLC–ICP-MS and ESI–MS, HPLC–ICP-MS helps to focus the ESI–MS selection of ions. Numerous studies have shown that the information obtained from HPLC–ICP-MS analysis can be greatly enhanced by complementary approaches. - Highlights: • HPLC–ICP-MS is the most common method used for arsenic speciation. • HPLC limitations include

  2. Complementary arsenic speciation methods: A review

    International Nuclear Information System (INIS)

    Nearing, Michelle M.; Koch, Iris; Reimer, Kenneth J.

    2014-01-01

    The toxicity of arsenic greatly depends on its chemical form and oxidation state (speciation) and therefore accurate determination of arsenic speciation is a crucial step in understanding its chemistry and potential risk. High performance liquid chromatography with inductively coupled mass spectrometry (HPLC–ICP-MS) is the most common analysis used for arsenic speciation but it has two major limitations: it relies on an extraction step (usually from a solid sample) that can be incomplete or alter the arsenic compounds; and it provides no structural information, relying on matching sample peaks to standard peaks. The use of additional analytical methods in a complementary manner introduces the ability to address these disadvantages. The use of X-ray absorption spectroscopy (XAS) with HPLC–ICP-MS can be used to identify compounds not extracted for HPLC–ICP-MS and provide minimal processing steps for solid state analysis that may help preserve labile compounds such as those containing arsenic-sulfur bonds, which can degrade under chromatographic conditions. On the other hand, HPLC–ICP-MS is essential in confirming organoarsenic compounds with similar white line energies seen by using XAS, and identifying trace arsenic compounds that are too low to be detected by XAS. The complementary use of electrospray mass spectrometry (ESI–MS) with HPLC–ICP-MS provides confirmation of arsenic compounds identified during the HPLC–ICP-MS analysis, identification of unknown compounds observed during the HPLC–ICP-MS analysis and further resolves HPLC–ICP-MS by identifying co-eluting compounds. In the complementary use of HPLC–ICP-MS and ESI–MS, HPLC–ICP-MS helps to focus the ESI–MS selection of ions. Numerous studies have shown that the information obtained from HPLC–ICP-MS analysis can be greatly enhanced by complementary approaches. - Highlights: • HPLC–ICP-MS is the most common method used for arsenic speciation. • HPLC limitations include

  3. Speciation of arsenic in bulk and rhizosphere soils from artisanal cooperative mines in Bolivia.

    Science.gov (United States)

    Acosta, Jose A; Arocena, Joselito M; Faz, Angel

    2015-11-01

    Soils near artisanal and small-scale gold mines (ASGM) have high arsenic (As) contents due to the presence of arsenopyrite in gold ores and accelerated accumulations due to mine wastes disposal practices and other mining activities. We determined the content and speciation to understand the fate and environmental risks of As accumulations in 24 bulk and 12 rhizosphere soil samples collected in the Virgen Del Rosario and the Rayo Rojo cooperative mines in the highlands of Bolivia. Mean total As contents in bulk and rhizosphere soils ranged from 13 to 64 mg kg(-1) and exceeded the soil environmental quality guidelines of Canada. Rhizosphere soils always contained at least twice the As contents in the bulk soil. Elemental mapping using 4×5 μm synchrotron-generated X-ray micro-beam revealed As accumulations in areas enriched with Fe. Results of As-X-ray Absorption Near Edge Spectroscopy (As-XANES) showed that only As(V) species was detectable in all samples regardless of As contents, size fractions and types of vegetation. Although the toxicity of As(V) is less than As(III), we suggest that As uptake of commonly-grazed vegetation by alpaca and llama must be determined to fully understand the environmental risks of high As in soils near ASGM in Bolivia. In addition, knowledge on the speciation of the As bio-accessible fraction will provide another useful information to better understand the fate and transfer of As from soils into the food chain in environments associated with the ASGM in Bolivia and other parts of the world. Copyright © 2014 Elsevier Ltd. All rights reserved.

  4. Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs

    KAUST Repository

    Yutkin, Maxim P.

    2017-08-25

    Low-salinity waterflooding (LSW) is ineffective when reservoir rock is strongly water-wet or when crude oil is not asphaltenic. Success of LSW relies heavily on the ability of injected brine to alter surface chemistry of reservoir crude-oil brine/rock (COBR) interfaces. Implementation of LSW in carbonate reservoirs is especially challenging because of high reservoir-brine salinity and, more importantly, because of high reactivity of the rock minerals. Both features complicate understanding of the COBR surface chemistries pertinent to successful LSW. Here, we tackle the complex physicochemical processes in chemically active carbonates flooded with diluted brine that is saturated with atmospheric carbon dioxide (CO2) and possibly supplemented with additional ionic species, such as sulfates or phosphates. When waterflooding carbonate reservoirs, rock equilibrates with the injected brine over short distances. Injected-brine ion speciation is shifted substantially in the presence of reactive carbonate rock. Our new calculations demonstrate that rock-equilibrated aqueous pH is slightly alkaline quite independent of injected-brine pH. We establish, for the first time, that CO2 content of a carbonate reservoir, originating from CO2-rich crude oil and gas, plays a dominant role in setting aqueous pH and rock-surface speciation. A simple ion-complexing model predicts the calcite-surface charge as a function of composition of reservoir brine. The surface charge of calcite may be positive or negative, depending on speciation of reservoir brine in contact with the calcite. There is no single point of zero charge; all dissolved aqueous species are charge determining. Rock-equilibrated aqueous composition controls the calcite-surface ion-exchange behavior, not the injected-brine composition. At high ionic strength, the electrical double layer collapses and is no longer diffuse. All surface charges are located directly in the inner and outer Helmholtz planes. Our evaluation of

  5. Nickel speciation in several serpentine (ultramafic) topsoils via bulk synchrotron-based techniques

    Energy Technology Data Exchange (ETDEWEB)

    Siebecker, Matthew G.; Chaney, Rufus L.; Sparks, Donald L.

    2017-07-01

    Serpentine soils have elevated concentrations of trace metals including nickel, cobalt, and chromium compared to non-serpentine soils. Identifying the nickel bearing minerals allows for prediction of potential mobility of nickel. Synchrotron-based techniques can identify the solid-phase chemical forms of nickel with minimal sample treatment. Element concentrations are known to vary among soil particle sizes in serpentine soils. Sonication is a useful method to physically disperse sand, silt and clay particles in soils. Synchrotron-based techniques and sonication were employed to identify nickel species in discrete particle size fractions in several serpentine (ultramafic) topsoils to better understand solid-phase nickel geochemistry. Nickel commonly resided in primary serpentine parent material such as layered-phyllosilicate and chain-inosilicate minerals and was associated with iron oxides. In the clay fractions, nickel was associated with iron oxides and primary serpentine minerals, such as lizardite. Linear combination fitting (LCF) was used to characterize nickel species. Total metal concentration did not correlate with nickel speciation and is not an indicator of the major nickel species in the soil. Differences in soil texture were related to different nickel speciation for several particle size fractionated samples. A discussion on LCF illustrates the importance of choosing standards based not only on statistical methods such as Target Transformation but also on sample mineralogy and particle size. Results from the F-test (Hamilton test), which is an underutilized tool in the literature for LCF in soils, highlight its usefulness to determine the appropriate number of standards to for LCF. EXAFS shell fitting illustrates that destructive interference commonly found for light and heavy elements in layered double hydroxides and in phyllosilicates also can occur in inosilicate minerals, causing similar structural features and leading to false positive results in

  6. Metal speciation: survey of environmental methods of analysis

    Energy Technology Data Exchange (ETDEWEB)

    Mach, M.H.; Nott, B.; Scott, J.W.; Maddalone, R.F.; Whiddon, N.T. [TRW, Redondo Beach, CA (United States). Chemistry Technology Dept.

    1996-07-01

    As part of a recent task under the EPRI Analytical Methods Qualification Program (RP 1851), TRW has surveyed the methods available for monitoring metal species in typical utility aqueous discharge streams. Methods for determining the individual species of these metals can become important in a regulatory sense as the EPA transitions to assessment of environmental risk based on bioavailability. For example, EPA considers methyl mercury and Cr(VI) much more toxic to the aquatic environment than inorganic mercury or Cr(III). The species of a given element can also differ in their transport and bioaccumulation. Methods for speciation generally include a selective separation step followed by standard metals analysis. Speciation, therefore, is mainly derived from the separation step and not from the method of final quantisation. Examples of separation/analysis include: selective extraction followed by graphite furnace atomic absorption or ICP-MS; separation by GC followed by metals detection; chelation and/or direct separation by LC followed by UV measurement or metals detection; and ion chromatography with conductivity, UV, or metals detection. There are a number of sampling issues associated with metal species such as stabilization (maintaining oxidation state), absorption, and filtration that need to be addressed in order to obtain and maintain a representative sample for analysis. 45 refs., 1 tab.

  7. Evaluation of mercury speciation by EPA (Draft) Method 29

    Energy Technology Data Exchange (ETDEWEB)

    Laudal, D.L.; Heidt, M.K. [Energy & Environmental Research Center, Grand Forks, ND (United States); Nott, B. [Electric Power Research Institute, Palo Alto, CA (United States)

    1995-11-01

    The 1990 Clean Air Act Amendments require that the U.S. Environmental protection Agency (EPA) assess the health risks associated with mercury emissions. Also, the law requires a separate assessment of health risks posed by the emission of 189 tract chemicals (including mercury) for electric utility steam-generating units. In order to conduct a meaningful assessment of health and environmental effects, we must have, among other things, a reliable and accurate method to measure mercury emissions. In addition, the rate of mercury deposition and the type of control strategies used may depend upon the type of mercury emitted (i.e., whether it is in the oxidized or elemental form). It has been speculated that EPA (Draft) Method 29 can speciate mercury by selective absorption; however, this claim has yet to be proven. The Electric Power Research Institute (EPRI) and the U.S. Department of Energy (DOE) have contracted with the Energy & Environmental Research Center (EERC) at University of North Dakota to evaluate EPA (Draft) Method 29 at the pilot-scale level. The objective of the work is to determine whether EPA (Draft) Method 29 can reliably quantify and speciate mercury in the flue gas from coal-fired boilers.

  8. Bulk solubility and speciation of plutonium(VI) in phosphate-containing solutions

    International Nuclear Information System (INIS)

    Weger, H.T.; Okajima, S.; Cunnane, J.C.; Reed, D.T.

    1992-01-01

    The solubility and speciation of Pu(VI) with phosphate as a function of pH was investigated to determine the ability of phosphate to act as an actinide getter. The general properties were first investigated and are reported here with the goal of performing more quantitative experiments in the future. Solubility was approached from oversaturation at initial pH = 4, 10 and 13.4. Absorption spectra were recorded, the solution filtered and the filtrate counted. Absorption spectra were obtained at varying phosphate concentrations and at pH of 2.7 to 11.9. The effect of complexation on the 833 mn Pu(VI) band was characterized. Evidence for three phosphate complexes was obtained for pH -5 to 10 -6 M Pu(VI) was measured in the filtrate at pH ≤ 10 that were passed through a 50 mn filter. Pu(VI) complexes with phosphate over hydroxide at pH ≤ 11.6, but at pH ≥ 11.9, only hydrolyzed Pu(VI) was detected. At pH = 12, the concentration of Pu(VI) was as high as 10 -4 M

  9. AN ANALYTICAL METHOD FOR CHEMICAL SPECIATION OF SELENIUM IN SOIL

    Directory of Open Access Journals (Sweden)

    Constantin Luca

    2010-10-01

    Full Text Available Selenium is an essential microelement, sometimes redoubtable, through its beneficial role - risk depending on its concentration in the food chain, at low dose is an important nutrient in the life of humans and animals, contrary at high doses, it becomes toxic. Selenium may be find itself in the environment (soil, sediment, water in many forms (oxidized, reduced, organometallic which determine their mobility and toxicity. Determination of chemical speciation (identification of different chemical forms provides much more complete information for a better understanding of the behavior and the potential impact on the environment. In this work we present the results of methodological research on the extraction of sequential forms of selenium in the soil and the coupling of analytical methods capable of identifying very small amounts of selenium in soils An efficient scheme of sequential extractions forms of selenium (SES consisting in atomic absorption spectrometry coupled with hydride generation (HGAAS has been developed into five experimental steps, detailed in the paper. This operational scheme has been applied to the analysis of chemical speciation in the following areas: the Bărăgan Plain and Central Dobrogea of Romania.

  10. Field Deployable Method for Arsenic Speciation in Water.

    Science.gov (United States)

    Voice, Thomas C; Flores Del Pino, Lisveth V; Havezov, Ivan; Long, David T

    2011-01-01

    Contamination of drinking water supplies by arsenic is a world-wide problem. Total arsenic measurements are commonly used to investigate and regulate arsenic in water, but it is well understood that arsenic occurs in several chemical forms, and these exhibit different toxicities. It is problematic to use laboratory-based speciation techniques to assess exposure as it has been suggested that the distribution of species is not stable during transport in some types of samples. A method was developed in this study for the on-site speciation of the most toxic dissolved arsenic species: As (III), As (V), monomethylarsonic acid (MMA) and dimethylarsenic acid (DMA). Development criteria included ease of use under field conditions, applicable at levels of concern for drinking water, and analytical performance.The approach is based on selective retention of arsenic species on specific ion-exchange chromatography cartridges followed by selective elution and quantification using graphite furnace atomic absorption spectroscopy. Water samples can be delivered to a set of three cartridges using either syringes or peristaltic pumps. Species distribution is stable at this point, and the cartridges can be transported to the laboratory for elution and quantitative analysis. A set of ten replicate spiked samples of each compound, having concentrations between 1 and 60 µg/L, were analyzed. Arsenic recoveries ranged from 78-112 % and relative standard deviations were generally below 10%. Resolution between species was shown to be outstanding, with the only limitation being that the capacity for As (V) was limited to approximately 50 µg/L. This could be easily remedied by changes in either cartridge design, or the extraction procedure. Recoveries were similar for two spiked hard groundwater samples indicating that dissolved minerals are not likely to be problematic. These results suggest that this methodology can be use for analysis of the four primary arsenic species of concern in

  11. Transport methods as complementary tools for speciation purposes

    International Nuclear Information System (INIS)

    Fourest, B.; Sladkov, V.

    2005-01-01

    Transport methods, and especially capillary electrophoresis, are shown to bring with a high simplicity and efficiently useful complementary data to solve some speciation problems. Their application in this aim is particularly interesting in the case of actinides or solutions resulting from the radioactive waste management. In the present article, three examples are proposed to illustrate this point. In the first one, the open-end capillary method is applied to point out the hydrolyzed species of Pa(V) over a wide pH range. The difficulties overcome in this case are related to the very low concentration and specific properties of the element under consideration. The second illustration concerns the complexation of uranyl by the anionic forms of some long-lived fission products (MO x n- , with M=I and Se). For the study of these systems, capillary electrophoresis appears to be a method particularly simple and efficient. The last example deals with the quantification of selenate and selenite ions in the presence of nitrate. Capillary electrophoresis is found to be especially appropriate to the simultaneous determination of these two anionic species in such media. (orig.)

  12. Development of analytical methods for iodine speciation in fresh water

    International Nuclear Information System (INIS)

    Takaku, Yuichi; Ohtsuka, Yoshihito; Hisamatsu, Shun'ichi

    2007-01-01

    Analytical methods for physicochemical speciation of iodine in fresh water samples were developed to elucidate its behavior in the environment. The methods combined inductively coupled plasma mass spectrometry (ICP-MS) with size exclusion high performance liquid chromatography (SEC) or capillary electrophoresis (CE). Freshwater samples were collected from Lake Towada and rivers surrounding the lake. After filtration through a 0.45 μm pore size membrane filter, iodine in the water samples was pre-concentrated with an ultra-filtration filter which had a cut-off size of 10 kDa. The fraction with molecular size over 10 kDa was concentrated to 100 times in the original water, and then introduced into the SEC-ICP-MS. Molecular size chromatograms of all river and lake water samples showed two peaks for iodine concentrations: 40 kDa and 20 kDa. The method for separately determining two valence states of inorganic iodine, I - and IO 3 - , was also developed using the CE-ICP-MS system and it was successfully applied to the fresh water samples. Analysis results of surface water samples in Lake Towada and rivers surrounding the lake indicated that the chemical form of inorganic iodine in all samples was IO 3 - . Additional lake water samples were collected from Lake O-ike-higashi in the Juni-ko area at Shirakami-Sanchi, which is a UNESCO natural world heritage. The lake has a strong thermocline during all seasons; its bottom layer is in a highly reductive state. Depth profiles of I - and IO 3 - clearly showed that I - was not detected in the surface layer, but it was predominant in the bottom layer, and vice versa for IO 3 - . As this separation method is rapid and sensitive, it will be widely used in the future. (author)

  13. Determining uranium speciation in Fernald soils by molecular spectroscopic methods

    International Nuclear Information System (INIS)

    Allen, P.G.; Berg, J.M.; Crisholm-Brause, C.J.; Conradson, S.D.; Donohoe, R.J.; Morris, D.E.; Musgrave, J.A.; Tait, C.D.

    1994-07-01

    This progress report describes new experimental results and interpretations for data collected from October 1, 1992, through September 30, 1993, as part of the Characterization Task of the Uranium in Soils Integrated Demonstration of the Office of Technology Development, Office of Environmental Restoration and Waste Management of the US Department of Energy. X-ray absorption, optical luminescence, and Raman vibrational spectroscopies were used to determine uranium speciation in contaminated soils from the US DOE's former uranium production facility at Fernald, Ohio. These analyses were carried out both before and after application of one of the various decontamination technologies being developed within the Integrated Demonstration. This year the program focused on characterization of the uranium speciation remaining in the soils after decontamination treatment. X-ray absorption and optical luminescence spectroscopic data were collected for approximately 40 Fernald soil samples, which were treated by one or more of the decontamination technologies

  14. Carbon nanotubes grown on bulk materials and methods for fabrication

    Science.gov (United States)

    Menchhofer, Paul A [Clinton, TN; Montgomery, Frederick C [Oak Ridge, TN; Baker, Frederick S [Oak Ridge, TN

    2011-11-08

    Disclosed are structures formed as bulk support media having carbon nanotubes formed therewith. The bulk support media may comprise fibers or particles and the fibers or particles may be formed from such materials as quartz, carbon, or activated carbon. Metal catalyst species are formed adjacent the surfaces of the bulk support material, and carbon nanotubes are grown adjacent the surfaces of the metal catalyst species. Methods employ metal salt solutions that may comprise iron salts such as iron chloride, aluminum salts such as aluminum chloride, or nickel salts such as nickel chloride. Carbon nanotubes may be separated from the carbon-based bulk support media and the metal catalyst species by using concentrated acids to oxidize the carbon-based bulk support media and the metal catalyst species.

  15. Comparison of three molecular methods for the detection and speciation of Plasmodium vivax and Plasmodium falciparum

    Directory of Open Access Journals (Sweden)

    Price Ric N

    2007-09-01

    Full Text Available Abstract Background Accurate diagnosis of Plasmodium spp. is essential for the rational treatment of malaria. Despite its many disadvantages, microscopic examination of blood smears remains the current "gold standard" for malaria detection and speciation. PCR assays offer an alternative to microscopy which has been shown to have superior sensitivity and specificity. Unfortunately few comparative studies have been done on the various molecular based speciation methods. Methods The sensitivity, specificity and cost effectiveness of three molecular techniques were compared for the detection and speciation of Plasmodium falciparum and Plasmodium vivax from dried blood spots collected from 136 patients in western Thailand. The results from the three molecular speciation techniques (nested PCR, multiplex PCR, and real-time PCR were used to develop a molecular consensus (two or more identical PCR results as an alternative gold standard. Results According to the molecular consensus, 9.6% (13/136 of microscopic diagnoses yielded false negative results. Multiplex PCR failed to detect P. vivax in three mixed isolates, and the nested PCR gave a false positive P. falciparum result in one case. Although the real-time PCR melting curve analysis was the most expensive method, it was 100% sensitive and specific and least time consuming of the three molecular techniques investigated. Conclusion Although microscopy remains the most appropriate method for clinical diagnosis in a field setting, its use as a gold standard may result in apparent false positive results by superior techniques. Future studies should consider using more than one established molecular methods as a new gold standard to assess novel malaria diagnostic kits and PCR assays.

  16. Bulk Electric Load Cost Calculation Methods: Iraqi Network Comparative Study

    Directory of Open Access Journals (Sweden)

    Qais M. Alias

    2016-09-01

    Full Text Available It is vital in any industry to regain the spent capitals plus running costs and a margin of profits for the industry to flourish. The electricity industry is an everyday life touching industry which follows the same finance-economic strategy. Cost allocation is a major issue in all sectors of the electric industry, viz, generation, transmission and distribution. Generation and distribution service costing’s well documented in the literature, while the transmission share is still of need for research. In this work, the cost of supplying a bulk electric load connected to the EHV system is calculated. A sample basic lump-average method is used to provide a rough costing guide. Also, two transmission pricing methods are employed, namely, the postage-stamp and the load-flow based MW-distance methods to calculate transmission share in the total cost of each individual bulk load. The three costing methods results are then analyzed and compared for the 400kV Iraqi power grid considered for a case study.

  17. Chromium speciation in environmental samples using a solid phase spectrophotometric method

    Science.gov (United States)

    Amin, Alaa S.; Kassem, Mohammed A.

    2012-10-01

    A solid phase extraction technique is proposed for preconcentration and speciation of chromium in natural waters using spectrophotometric analysis. The procedure is based on sorption of chromium(III) as 4-(2-benzothiazolylazo)2,2'-biphenyldiol complex on dextran-type anion-exchange gel (Sephadex DEAE A-25). After reduction of Cr(VI) by 0.5 ml of 96% concentrated H2SO4 and ethanol, the system was applied to the total chromium. The concentration of Cr(VI) was calculated as the difference between the total Cr and the Cr(III) content. The influences of some analytical parameters such as: pH of the aqueous solution, amounts of 4-(2-benzothiazolylazo)2,2'-biphenyldiol (BTABD), and sample volumes were investigated. The absorbance of the gel, at 628 and 750 nm, packed in a 1.0 mm cell, is measured directly. The molar absorptivities were found to be 2.11 × 107 and 3.90 × 107 L mol-1 cm-1 for 500 and 1000 ml, respectively. Calibration is linear over the range 0.05-1.45 μg L-1 with RSD of <1.85% (n = 8.0). Using 35 mg exchanger, the detection and quantification limits were 13 and 44 ng L-1 for 500 ml sample, whereas for 1000 ml sample were 8.0 and 27 ng L-1, respectively. Increasing the sample volume can enhance the sensitivity. No considerable interferences have been observed from other investigated anions and cations on the chromium speciation. The proposed method was applied to the speciation of chromium in natural waters and total chromium preconcentration in microwave digested tobacco, coffee, tea, and soil samples. The results were simultaneously compared with those obtained using an ET AAS method, whereby the validity of the method has been tested.

  18. Speciative determination of phosphorus in environmental water by the isotope exchange method

    International Nuclear Information System (INIS)

    Ikeda, N.; Yoshikawa, M.; Murakami, S.; Kunika, J.

    1988-01-01

    An isotope exchage method for the speciative determination of phosphorus (PO 4 3- ,PO 3 3- and total P) in natural water samples is proposed by using the exchange system of molybdophosphate in the aqueous phase and tetraphenylarsonium molybdophosphate in the organic phase. In this exchange system, only PO 4 3- exchanges and is determined. When the sample water is treated with Br 2 water in advance, the amount of PO 4 3- +PO 3 3- can be obtained. When the sample is treated with H 2 SO 4 and HNO 3 , the amount of total P can be determined. (author) 4 refs.; 5 tabs

  19. Redox speciation of final repository relevant elements using separation methods in combination with ICP mass spectrometry

    International Nuclear Information System (INIS)

    Graser, Carl-Heinrich

    2015-01-01

    The long-term safety assessment for nuclear waste repositories requires a detailed understanding of the chemistry of actinide elements in the geosphere. The development of advanced analytical tools is required to gain detailed insights into actinide redox speciation in a given system. The mobility of radionuclides is mostly determined by the geochemical conditions which control the redox state of radionuclides. Besides the longlived radionuclides plutonium (Pu) and neptunium (Np), which are key elements in high level nuclear waste, iron (Fe) represents a main component in natural systems controlling redox related geochemical processes. Analytical techniques for determining oxidation state distribution for redox sensitive radionuclides and other metal ions often have a lack of sensitivity. The detection limits of these methods (i.e. UV/vis, TRLFS, XANES) are in general in the range of ≥ 10 -6 mol.L -1 . As a consequence ultrasensitive new analytical techniques are required. Capillary electrophoresis (CE) and ion chromatography (IC) are powerful separation methods for metal ions. In the course of this thesis different speciation method for iron, neptunium and plutonium were optimized. With the optimized setup redox speciation analysis of these elements in different samples were done. Furthermore CE hyphenated to inductively coupled plasma sector field mass spectrometry (CE - ICP - SF - MS) was used to measure the redox speciation of Pu (III, IV, V, VI), Np (IV, V, VI) and Fe (II, III) at concentrations lower than 10 -7 mol.L -1 . CE coupling and separation parameters such as sample gas pressure, make up flow rate, capillary position, auxiliary gas flow, as well as the electrolyte system were optimized to obtain the maximum sensitivity. The methodes detection limits are 10 -12 mol.L -1 for Np and Pu. The various oxidation state species of Pu and Np in different samples were separated by application of an acetate based electrolyte system. The separation of Fe (II

  20. An empirical method to estimate bulk particulate refractive index for ocean satellite applications

    Digital Repository Service at National Institute of Oceanography (India)

    Suresh, T.; Desa, E.; Mascarenhas, A.A.M.Q.; Matondkar, S.G.P.; Naik, P.; Nayak, S.R.

    An empirical method is presented here to estimates bulk particulate refractive index using the measured inherent and apparent optical properties from the various waters types of the Arabian Sea. The empirical model, where the bulk refractive index...

  1. Application of the Rietveld method to assess chromium(VI) speciation in chromite ore processing residue

    International Nuclear Information System (INIS)

    Chrysochoou, Maria; Dermatas, Dimitris

    2007-01-01

    The Rietveld method allows the quantification of crystalline phases and amorphous material identified by X-ray powder diffraction (XRPD) and other diffraction methods. The method assists in determining the speciation of contaminants in solid matrices both qualitatively and quantitatively in a statistically defensible approach, as it does not focus on a microscale. Rietveld was applied to chromite ore processing residue (COPR), a cementitious waste containing hexavalent chromium. Calcium aluminum chromium oxide hydrates (CACs) were the crystalline phases identified by XRPD that bind Cr 6+ in COPR according to their chemical formula. Rietveld quantification, combined with mass balances on Cr 6+ , showed that CACs may bind Cr 6+ in variable percentages, ranging from 25% to 85%. Analysis of duplicate samples showed that material variability is the predominant factor of uncertainty in evaluating the role of CACs in Cr 6+ speciation, provided that a consistent quantification strategy is pursued. The choice of strategy was performed on the basis of the pertinent literature, preliminary analyses of the equipment and the software settings, and mass balances. The correlation between the average CAC-bound Cr 6+ concentration and the total Cr 6+ for five samples (R 2 = 0.94), extracted from different zones and soil borings, suggests that CACs are a primary sink for Cr 6+ in COPR

  2. Field and laboratory arsenic speciation methods and their application to natural-water analysis

    Science.gov (United States)

    Bednar, A.J.; Garbarino, J.R.; Burkhardt, M.R.; Ranville, J.F.; Wildeman, T.R.

    2004-01-01

    The toxic and carcinogenic properties of inorganic and organic arsenic species make their determination in natural water vitally important. Determination of individual inorganic and organic arsenic species is critical because the toxicology, mobility, and adsorptivity vary substantially. Several methods for the speciation of arsenic in groundwater, surface-water, and acid mine drainage sample matrices using field and laboratory techniques are presented. The methods provide quantitative determination of arsenite [As(III)], arsenate [As(V)], monomethylarsonate (MMA), dimethylarsinate (DMA), and roxarsone in 2-8min at detection limits of less than 1??g arsenic per liter (??g AsL-1). All the methods use anion exchange chromatography to separate the arsenic species and inductively coupled plasma-mass spectrometry as an arsenic-specific detector. Different methods were needed because some sample matrices did not have all arsenic species present or were incompatible with particular high-performance liquid chromatography (HPLC) mobile phases. The bias and variability of the methods were evaluated using total arsenic, As(III), As(V), DMA, and MMA results from more than 100 surface-water, groundwater, and acid mine drainage samples, and reference materials. Concentrations in test samples were as much as 13,000??g AsL-1 for As(III) and 3700??g AsL-1 for As(V). Methylated arsenic species were less than 100??g AsL-1 and were found only in certain surface-water samples, and roxarsone was not detected in any of the water samples tested. The distribution of inorganic arsenic species in the test samples ranged from 0% to 90% As(III). Laboratory-speciation method variability for As(III), As(V), MMA, and DMA in reagent water at 0.5??g AsL-1 was 8-13% (n=7). Field-speciation method variability for As(III) and As(V) at 1??g AsL-1 in reagent water was 3-4% (n=3). ?? 2003 Elsevier Ltd. All rights reserved.

  3. Estimating forest canopy bulk density using six indirect methods

    Science.gov (United States)

    Robert E. Keane; Elizabeth D. Reinhardt; Joe Scott; Kathy Gray; James Reardon

    2005-01-01

    Canopy bulk density (CBD) is an important crown characteristic needed to predict crown fire spread, yet it is difficult to measure in the field. Presented here is a comprehensive research effort to evaluate six indirect sampling techniques for estimating CBD. As reference data, detailed crown fuel biomass measurements were taken on each tree within fixed-area plots...

  4. Speciation and detection of arsenic in aqueous samples: A review of recent progress in non-atomic spectrometric methods

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Jian [State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen 361102 (China); Department of Chemistry and Biochemistry, University of Texas, 700 Planetarium Place, Arlington, TX 76019 (United States); Sengupta, Mrinal K. [Department of Chemistry and Biochemistry, University of Texas, 700 Planetarium Place, Arlington, TX 76019 (United States); Thermo Fisher Scientific, Dionex Products, 445 Lakeside Drive, Sunnyvale, CA, 94085 (United States); Yuan, Dongxing [State Key Laboratory of Marine Environmental Science, College of the Environment and Ecology, Xiamen University, Xiamen 361102 (China); Dasgupta, Purnendu K., E-mail: Dasgupta@uta.edu [Department of Chemistry and Biochemistry, University of Texas, 700 Planetarium Place, Arlington, TX 76019 (United States)

    2014-06-01

    Highlights: • Compilation of principal official documents and major review articles, including the toxicology and chemistry of As. • Review of non-atomic spectrometric methods for speciation and detection of arsenic in aqueous samples (2005–2013) of the performance of field-usable methods. - Abstract: Inorganic arsenic (As) displays extreme toxicity and is a class A human carcinogen. It is of interest to both analytical chemists and environmental scientists. Facile and sensitive determination of As and knowledge of the speciation of forms of As in aqueous samples are vitally important. Nearly every nation has relevant official regulations on permissible limits of drinking water As content. The size of the literature on As is therefore formidable. The heart of this review consists of two tables: one is a compilation of principal official documents and major review articles, including the toxicology and chemistry of As. This includes comprehensive official compendia on As speciation, sample treatment, recommended procedures for the determination of As in specific sample matrices with specific analytical instrument(s), procedures for multi-element (including As) speciation and analysis, and prior comprehensive reviews on arsenic analysis. The second table focuses on the recent literature (2005–2013, the coverage for 2013 is incomplete) on As measurement in aqueous matrices. Recent As speciation and analysis methods based on spectrometric and electrochemical methods, inductively coupled plasma-mass spectrometry, neutron activation analysis and biosensors are summarized. We have deliberately excluded atomic optical spectrometric techniques (atomic absorption, atomic fluorescence, inductively coupled plasma-optical emission spectrometry) not because they are not important (in fact the majority of arsenic determinations are possibly carried out by one of these techniques) but because these methods are sufficiently mature and little meaningful innovation has been

  5. Speciation and detection of arsenic in aqueous samples: A review of recent progress in non-atomic spectrometric methods

    International Nuclear Information System (INIS)

    Ma, Jian; Sengupta, Mrinal K.; Yuan, Dongxing; Dasgupta, Purnendu K.

    2014-01-01

    Highlights: • Compilation of principal official documents and major review articles, including the toxicology and chemistry of As. • Review of non-atomic spectrometric methods for speciation and detection of arsenic in aqueous samples (2005–2013) of the performance of field-usable methods. - Abstract: Inorganic arsenic (As) displays extreme toxicity and is a class A human carcinogen. It is of interest to both analytical chemists and environmental scientists. Facile and sensitive determination of As and knowledge of the speciation of forms of As in aqueous samples are vitally important. Nearly every nation has relevant official regulations on permissible limits of drinking water As content. The size of the literature on As is therefore formidable. The heart of this review consists of two tables: one is a compilation of principal official documents and major review articles, including the toxicology and chemistry of As. This includes comprehensive official compendia on As speciation, sample treatment, recommended procedures for the determination of As in specific sample matrices with specific analytical instrument(s), procedures for multi-element (including As) speciation and analysis, and prior comprehensive reviews on arsenic analysis. The second table focuses on the recent literature (2005–2013, the coverage for 2013 is incomplete) on As measurement in aqueous matrices. Recent As speciation and analysis methods based on spectrometric and electrochemical methods, inductively coupled plasma-mass spectrometry, neutron activation analysis and biosensors are summarized. We have deliberately excluded atomic optical spectrometric techniques (atomic absorption, atomic fluorescence, inductively coupled plasma-optical emission spectrometry) not because they are not important (in fact the majority of arsenic determinations are possibly carried out by one of these techniques) but because these methods are sufficiently mature and little meaningful innovation has been

  6. Porosity, Bulk Density, and Volume Reduction During Drying: Review of Measurement Methods and Coefficient Determinations

    NARCIS (Netherlands)

    Qiu, J.; Khalloufi, S.; Martynenko, A.; Dalen, van G.; Schutyser, M.A.I.; Almeida-Rivera, C.

    2015-01-01

    Several experimental methods for measuring porosity, bulk density and volume reduction during drying of foodstuff are available. These methods include among others geometric dimension, volume displacement, mercury porosimeter, micro-CT, and NMR. However, data on their accuracy, sensitivity, and

  7. A new method of preventing bulk-Si CMOS devices from latchup

    International Nuclear Information System (INIS)

    Xu Xianguo; Xu Xi

    2004-01-01

    A new method, pseudo-latchup path method, has been put forward that is based on latchup effects of bulk-Si CMOS devices. After we study the design of pseudo-latchup path method in detail, a practice and the corresponding simulation result by computer are given in this text. Pseudo-latchup path method can be used to prevent permanent latchup, but it cannot be used to eliminate the dose rate upset of bulk-Si CMOS devices. (authors)

  8. Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative

    Energy Technology Data Exchange (ETDEWEB)

    Bulut, Volkan Numan; Ozdes, Duygu; Bekircan, Olcay; Gundogdu, Ali; Duran, Celal [Department of Chemistry, Karadeniz Technical University, Faculty of Arts and Sciences, 61080 Trabzon (Turkey); Soylak, Mustafa [Department of Chemistry, Erciyes University, Faculty of Arts and Sciences, 38039 Kayseri (Turkey)], E-mail: soylak@erciyes.edu.tr

    2009-01-19

    A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H{sub 2}SO{sub 4} and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N = 10) was found 0.7 {mu}g L{sup -1}. The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values.

  9. Carrier element-free coprecipitation (CEFC) method for the separation, preconcentration and speciation of chromium using an isatin derivative

    International Nuclear Information System (INIS)

    Bulut, Volkan Numan; Ozdes, Duygu; Bekircan, Olcay; Gundogdu, Ali; Duran, Celal; Soylak, Mustafa

    2009-01-01

    A new, simple, rapid and sensitive separation, preconcentration and speciation procedure for chromium in environmental liquid and solid samples has been established. The present speciation procedure for Cr(III) and Cr(VI) is based on combination of carrier element-free coprecipitation (CEFC) and flame atomic absorption spectrometric (FAAS) determinations. In this method a newly synthesized organic coprecipitant, 5-chloro-3-[4-(trifluoromethoxy) phenylimino]indolin-2-one (CFMEPI), was used without adding any carrier element for coprecipitation of chromium(III). After reduction of chromium(VI) by concentrated H 2 SO 4 and ethanol, the procedure was applied for the determination of total chromium. Chromium(VI) was calculated as the difference between the amount of total chromium and chromium(III). The optimum conditions for coprecipitation and speciation processes were investigated on several commonly tested experimental parameters, such as pH of the solution, amount of coprecipitant, sample volume, etc. No considerable interference was observed from the other investigated anions and cations, which may be found in natural water samples. The preconcentration factor was found to be 40. The detection limit for chromium(III) corresponding to three times the standard deviation of the blank (N = 10) was found 0.7 μg L -1 . The present procedure was successfully applied for speciation of chromium in several liquid and solid environmental samples. In order to support the accuracy of the method, the certified reference materials (CRM-TMDW-500 Drinking Water and CRM-SA-C Sandy Soil C) were analyzed, and standard APDC-MIBK liquid-liquid extraction method was performed. The results obtained were in good agreement with the certified values

  10. Methods for Investigating Mercury Speciation, Transport, Methylation, and Bioaccumulation in Watersheds Affected by Historical Mining

    Science.gov (United States)

    Alpers, C. N.; Marvin-DiPasquale, M. C.; Fleck, J.; Ackerman, J. T.; Eagles-Smith, C.; Stewart, A. R.; Windham-Myers, L.

    2016-12-01

    Many watersheds in the western U.S. have mercury (Hg) contamination from historical mining of Hg and precious metals (gold and silver), which were concentrated using Hg amalgamation (mid 1800's to early 1900's). Today, specialized sampling and analytical protocols for characterizing Hg and methylmercury (MeHg) in water, sediment, and biota generate high-quality data to inform management of land, water, and biological resources. Collection of vertically and horizontally integrated water samples in flowing streams and use of a Teflon churn splitter or cone splitter ensure that samples and subsamples are representative. Both dissolved and particulate components of Hg species in water are quantified because each responds to different hydrobiogeochemical processes. Suspended particles trapped on pre-combusted (Hg-free) glass- or quartz-fiber filters are analyzed for total mercury (THg), MeHg, and reactive divalent mercury. Filtrates are analyzed for THg and MeHg to approximate the dissolved fraction. The sum of concentrations in particulate and filtrate fractions represents whole water, equivalent to an unfiltered sample. This approach improves upon analysis of filtered and unfiltered samples and computation of particulate concentration by difference; volume filtered is adjusted based on suspended-sediment concentration to minimize particulate non-detects. Information from bed-sediment sampling is enhanced by sieving into multiple size fractions and determining detailed grain-size distribution. Wet sieving ensures particle disaggregation; sieve water is retained and fines are recovered by centrifugation. Speciation analysis by sequential extraction and examination of heavy mineral concentrates by scanning electron microscopy provide additional information regarding Hg mineralogy and geochemistry. Biomagnification of MeHg in food webs is tracked using phytoplankton, zooplankton, aquatic and emergent vegetation, invertebrates, fish, and birds. Analysis of zooplankton in

  11. Bulk superhard B-C-N nanocomposite compact and method for preparing thereof

    Science.gov (United States)

    Zhao, Yusheng; He, Duanwei

    2004-07-06

    Bulk, superhard, B-C-N nanocomposite compact and method for preparing thereof. The bulk, superhard, nanocomposite compact is a well-sintered compact and includes nanocrystalline grains of at least one high-pressure phase of B-C-N surrounded by amorphous diamond-like carbon grain boundaries. The bulk compact has a Vicker's hardness of about 41-68 GPa. It is prepared by ball milling a mixture of graphite and hexagonal boron nitride, encapsulating the ball-milled mixture, and sintering the encapsulated ball-milled mixture at a pressure of about 5-25 GPa and at a temperature of about 1000-2500 K.

  12. A new measurement method for quantification and speciation of technetium-99 in sample at environmental concentrations

    International Nuclear Information System (INIS)

    Kasprzak, L.M.; Aubert, C.; Cossonnet, C.; Fattahi, M.

    2006-01-01

    Technetium-99 is a pure β- emitter and important long half-lived multi-valent radionuclide to be considered in radiation protection of the environment and the public. It a fission product of both 235 U and 239 Pu with approximately a 6% yield. The most stable and very mobile form of Tc is the pertechnetate anion (TcO 4 - ). Therefore, environmental monitoring requires the knowledge of the redox and chemical properties of this element in order to predict its behaviour and transfer in the environment. Given the extremely low concentration of 99 Tc in the environment (10 -10 M to 10 -12 M), its determination currently necessitates an enrichment and separation from the sample matrix prior to instrumental measurement. To this end, the development of a suitable analytical technique is required. The advantages of Capillary Electrophoresis (CE) as a powerful separation technique can be combined with the atomic specificity, multi-elemental character and extremely high sensitivity of an inductively coupled plasma mass spectrometer (ICP-MS) for trace metal-speciation studies in different fields of interest. However, the coupling of both commercially available instruments deserves particular attention if separative resolution, high analyte transport efficiency and sensitive detection are to be achieved. In, that technical vein, the interface itself may be considered as the 'key to success'. Several attempts to develop interfaces for CE-ICP-MS have been described over the last few years. However, the 99 Tc quantification by ICP-MS can be disturbed by isobaric overlaps 99 Ru and interferences induced by the matrix, including those associated with hydride formation ( 98 Mo 1 H (23.8%), 98 Ru 1 H (1.9%)). The aim of the present study was to develop a rapid and efficient method for the determination of 99 Tc in environmental samples by CE-ICP-MS without preliminary classical radiochemical separation to eliminate the interfering elements. In this paper, we describe the development

  13. A new measurement method for quantification and speciation of technetium-99 in sample at environmental concentrations

    Energy Technology Data Exchange (ETDEWEB)

    Kasprzak, L.M. [IRSN/DEI/STEME/LMRE, ORSAY, F-91400 (France); SUBATECH, EMN-IN2P3/CNRS-Universit Nantes, F-44307 (France); Aubert, C.; Cossonnet, C. [IRSN/DEI/STEME/LMRE, ORSAY, F-91400 (France); Fattahi, M. [SUBATECH, EMN-IN2P3/CNRS-Universit Nantes, F-44307 (France)

    2006-07-01

    Technetium-99 is a pure {beta}- emitter and important long half-lived multi-valent radionuclide to be considered in radiation protection of the environment and the public. It a fission product of both {sup 235}U and {sup 239}Pu with approximately a 6% yield. The most stable and very mobile form of Tc is the pertechnetate anion (TcO{sub 4}{sup -}). Therefore, environmental monitoring requires the knowledge of the redox and chemical properties of this element in order to predict its behaviour and transfer in the environment. Given the extremely low concentration of {sup 99}Tc in the environment (10{sup -10} M to 10{sup -12} M), its determination currently necessitates an enrichment and separation from the sample matrix prior to instrumental measurement. To this end, the development of a suitable analytical technique is required. The advantages of Capillary Electrophoresis (CE) as a powerful separation technique can be combined with the atomic specificity, multi-elemental character and extremely high sensitivity of an inductively coupled plasma mass spectrometer (ICP-MS) for trace metal-speciation studies in different fields of interest. However, the coupling of both commercially available instruments deserves particular attention if separative resolution, high analyte transport efficiency and sensitive detection are to be achieved. In, that technical vein, the interface itself may be considered as the 'key to success'. Several attempts to develop interfaces for CE-ICP-MS have been described over the last few years. However, the {sup 99}Tc quantification by ICP-MS can be disturbed by isobaric overlaps {sup 99}Ru and interferences induced by the matrix, including those associated with hydride formation ({sup 98}Mo{sup 1}H (23.8%), {sup 98}Ru{sup 1}H (1.9%)). The aim of the present study was to develop a rapid and efficient method for the determination of {sup 99}Tc in environmental samples by CE-ICP-MS without preliminary classical radiochemical separation to

  14. Technique of Critical Current Density Measurement of Bulk Superconductor with Linear Extrapolation Method

    International Nuclear Information System (INIS)

    Adi, Wisnu Ari; Sukirman, Engkir; Winatapura, Didin S.

    2000-01-01

    Technique of critical current density measurement (Jc) of HTc bulk ceramic superconductor has been performed by using linear extrapolation with four-point probes method. The measurement of critical current density HTc bulk ceramic superconductor usually causes damage in contact resistance. In order to decrease this damage factor, we introduce extrapolation method. The extrapolating data show that the critical current density Jc for YBCO (123) and BSCCO (2212) at 77 K are 10,85(6) Amp.cm - 2 and 14,46(6) Amp.cm - 2, respectively. This technique is easier, simpler, and the use of the current flow is low, so it will not damage the contact resistance of the sample. We expect that the method can give a better solution for bulk superconductor application. Key words. : superconductor, critical temperature, and critical current density

  15. Bulk characterization methods for non-centrosymmetric materials: second-harmonic generation, piezoelectricity, pyroelectricity, and ferroelectricity.

    Science.gov (United States)

    Ok, Kang Min; Chi, Eun Ok; Halasyamani, P Shiv

    2006-08-01

    Characterization methods for bulk non-centrosymmetric compounds are described. These methods include second-harmonic generation, piezoelectricity, pyroelectricity, and ferroelectricity. In this tutorial review with each phenomenon, details are given of the measurement techniques along with a brief history and background. Finally, data interpretation is discussed.

  16. Improvement of a magnetization method on a small-size superconducting bulk magnet system

    International Nuclear Information System (INIS)

    Yokoyama, K.; Oka, T.; Noto, K.

    2011-01-01

    This paper proposed an effective magnetizing method of high-T c bulk superconductors. The magnetic pass was artificially formed by field-cooling using a permanent magnet. The trapped field was increased by 20-25% as compared with the conventional method. We observed that the channel was formed partially in the trapped field distribution. A pulsed-filed magnetization (PFM) is an important technique for industrial applications of superconducting bulk magnets, and several advanced PFM methods are proposed to enhance the trapped field. In the well-known IMRA method, the channel through the magnetic flux is formed by the flux flow caused by heat generation when applying the strong pulsed-field, and the magnetic flux is made to penetrate into the bulk through the channel in the following pulse application. On the other hand, large applied field leads to large heat generation, and, therefore, the trapped field is decreased greatly. This paper proposes an effective magnetizing method in which the channel composed of magnetic field is artificially formed by field-cooling (FC) using a permanent magnet and the magnetic flux by PFM is induced to the channel. To confirm the validity of this method, the bulk was magnetized by FC using Nd-Fe-B magnets of the rectangular and the ring shapes, and thereafter, a pulsed-field of 6.2 T was applied. As a result, the trapped field of the bulk magnetized by FC using the ring magnet was increased by about 20-25% as compared with that of the conventional PFM, and, moreover, it was observed that the channel was formed partially by measurement of the magnetic field distribution.

  17. Use of thermal neutron reflection method for chemical analysis of bulk samples

    International Nuclear Information System (INIS)

    Papp, A.; Csikai, J.

    2014-01-01

    Microscopic, σ β , and macroscopic, Σ β , reflection cross-sections of thermal neutrons averaged over bulk samples as a function of thickness (z) are given. The σ β values are additive even for bulk samples in the z=0.5–8 cm interval and so the σ βmol (z) function could be given for hydrogenous substances, including some illicit drugs, explosives and hiding materials of ∼1000 cm 3 dimensions. The calculated excess counts agree with the measured R(z) values. For the identification of concealed objects and chemical analysis of bulky samples, different neutron methods need to be used simultaneously. - Highlights: • Check the proposed analytical expression for the description of the flux. • Determination of the reflection cross-sections averaged over bulk samples. • Data rendered to estimate the excess counts for various materials

  18. Use of thermal neutron reflection method for chemical analysis of bulk samples

    Energy Technology Data Exchange (ETDEWEB)

    Papp, A., E-mail: papppa@atomki.hu [Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI), 4001 Debrecen, Pf. 51 (Hungary); Csikai, J. [Institute of Nuclear Research of the Hungarian Academy of Sciences, (ATOMKI), 4001 Debrecen, Pf. 51 (Hungary); Institute of Experimental Physics, University Debrecen (IEP), 4010 Debrecen-10, Pf. 105 (Hungary)

    2014-09-11

    Microscopic, σ{sub β}, and macroscopic, Σ{sub β}, reflection cross-sections of thermal neutrons averaged over bulk samples as a function of thickness (z) are given. The σ{sub β} values are additive even for bulk samples in the z=0.5–8 cm interval and so the σ{sub βmol}(z) function could be given for hydrogenous substances, including some illicit drugs, explosives and hiding materials of ∼1000 cm{sup 3} dimensions. The calculated excess counts agree with the measured R(z) values. For the identification of concealed objects and chemical analysis of bulky samples, different neutron methods need to be used simultaneously. - Highlights: • Check the proposed analytical expression for the description of the flux. • Determination of the reflection cross-sections averaged over bulk samples. • Data rendered to estimate the excess counts for various materials.

  19. Determination of prilocaine HCl in bulk drug and pharmaceutical formulation by GC-NPD method

    Directory of Open Access Journals (Sweden)

    Atila Alptug

    2013-01-01

    Full Text Available The novel analytical method was developed and validated for determination of prilocaine HCl in bulk drug and pharmaceutical formulation by gas chromatography-nitrogen phosphorus detection (GC-NPD. The chromatographic separation was performed using a HP-5MS column. The calibration curve was linear over the concentration range of 40-1000 ng ml-1 with a correlation coefficient of 0.9998. The limits of detection (LOD and quantification (LOQ of method were 10 ng ml-1 and 35 ng ml-1, respectively. The within-day and between-day precision, expressed as the percent relative standard deviation (RSD% was less than 5.0%, and accuracy (percent relative error was better than 4.0%. The developed method can be directly and easily applied for determination of prilocaine HCl in bulk drug and pharmaceutical formulation using internal standard methodology.

  20. HPTLC Method Development and Validation of Zolpidem Tartrate in Bulk and Marketed Formulation

    OpenAIRE

    Abhay R. Shirode; Bharti G. Jadhav; Vilasrao J. Kadam

    2015-01-01

    High performance thin layer chromatography (HPTLC) offers many advantages over HPLC. It reduces the cost of analysis as compare to HPLC. The mobile phase consumption per sample is extremely low in HPTLC, hence reducing the acquisition and disposal cost. Considering the cost and suitability of analysis for estimation of zolpidem tartrate in bulk and its marketed formulation, HPTLC method was developed and validated. The Camag HPTLC system, employed with software winCATS (ver.1.4.1.8) was used ...

  1. Voltammetric methods for determination and speciation of inorganic arsenic in the environment-A review

    Energy Technology Data Exchange (ETDEWEB)

    Mays, Douglas E. [Centre for Clean Water and Sustainable Technologies, Department of Chemistry and Biochemistry, George Mason University, Fairfax, VA 20120 (United States); Hussam, Abul, E-mail: ahussam@gmu.edu [Centre for Clean Water and Sustainable Technologies, Department of Chemistry and Biochemistry, George Mason University, Fairfax, VA 20120 (United States)

    2009-07-30

    The measurement of inorganic arsenic in the environment has received considerable attention over the past 40+ years due to its toxicity and prevalence in drinking water. This paper provides an overview of voltammetric techniques used since 2001. More than fifty papers from refereed analytical chemistry journals on the speciation and measurement of inorganic arsenic (As(III) and As(V)) in practical and environmental samples are included. The present review shows that stripping voltammetry is a sensitive and inexpensive technique. The new approaches include development of novel measurement protocols through media variation, development and use of new boron doped diamond electrodes modified with metals, nano Au-modified electrodes on carbon or carbon nano-tubes, novel rotating disc and vibrating electrodes to enhance mass transfer, and modified Hg(l) and thin film Bi on carbon for cathodic stripping voltammetry are discussed. Although, majority of the papers were of exploratory in nature, the trend towards developing a commercial standalone instrument for field use is still in progress.

  2. Bulk synthesis of nanocrystalline urania powders by citrate gel-combustion method

    Science.gov (United States)

    Sanjay Kumar, D.; Ananthasivan, K.; Venkata Krishnan, R.; Amirthapandian, S.; Dasgupta, Arup

    2016-01-01

    Bulk quantities (60 g) of nanocrystalline (nc) free flowing urania powders with crystallite size ranging from 38 to 252 nm have been synthesized for the first time by the citrate gel combustion method. A systematic study of the influence of the fuel (citric acid) to oxidant (nitrate) ratio (R) on the characteristics of the urania powders has been carried out for the first time. Mixture with an "R" value of 0.25 exhibited a vigorous auto-ignition reaction. This reaction was investigated with Differential Scanning Calorimetry (DSC) and in-situ thermogravimetry coupled with differential thermal analysis and mass spectrometry (TG-DTA-MS). The bulk density, specific surface area, X-ray crystallite size, residual carbon and size distribution of particles of this powder were unique. Microscopic and microstructural investigation of selected samples revealed the presence of nanocrystals with irregular exfoliated morphology; their Electron Energy Loss Spectra testified the covalency of the U-O bond.

  3. Bulk synthesis of nanocrystalline urania powders by citrate gel-combustion method

    International Nuclear Information System (INIS)

    Sanjay Kumar, D.; Ananthasivan, K.; Venkata Krishnan, R.; Amirthapandian, S.; Dasgupta, Arup

    2016-01-01

    Bulk quantities (60 g) of nanocrystalline (nc) free flowing urania powders with crystallite size ranging from 38 to 252 nm have been synthesized for the first time by the citrate gel combustion method. A systematic study of the influence of the fuel (citric acid) to oxidant (nitrate) ratio (R) on the characteristics of the urania powders has been carried out for the first time. Mixture with an “R” value of 0.25 exhibited a vigorous auto-ignition reaction. This reaction was investigated with Differential Scanning Calorimetry (DSC) and in-situ thermogravimetry coupled with differential thermal analysis and mass spectrometry (TG-DTA-MS). The bulk density, specific surface area, X-ray crystallite size, residual carbon and size distribution of particles of this powder were unique. Microscopic and microstructural investigation of selected samples revealed the presence of nanocrystals with irregular exfoliated morphology; their Electron Energy Loss Spectra testified the covalency of the U–O bond. - Highlights: • Bulk quantities of nanocrystalline urania were prepared for the first time using citrate gel combustion method. • Volume combustion was observed in mixtures with fuel to nitrate ratio (R) 0.25. • The value of R was found to significantly influence the characteristics of the final product. • Typical exfoliated microstructure and nanopores were observed. • Established correlation between particle size distribution and bulk density, X-ray crystallite size and lattice strain. • Relationship between fuel to nitrate (R) mole ratio and physical characteristics of powders were also established.

  4. A Generalizable Top-Down Nanostructuring Method of Bulk Oxides: Sequential Oxygen-Nitrogen Exchange Reaction.

    Science.gov (United States)

    Lee, Lanlee; Kang, Byungwuk; Han, Suyoung; Kim, Hee-Eun; Lee, Moo Dong; Bang, Jin Ho

    2018-05-27

    A thermal reaction route that induces grain fracture instead of grain growth is devised and developed as a top-down approach to prepare nanostructured oxides from bulk solids. This novel synthesis approach, referred to as the sequential oxygen-nitrogen exchange (SONE) reaction, exploits the reversible anion exchange between oxygen and nitrogen in oxides that is driven by a simple two-step thermal treatment in ammonia and air. Internal stress developed by significant structural rearrangement via the formation of (oxy)nitride and the creation of oxygen vacancies and their subsequent combination into nanopores transforms bulk solid oxides into nanostructured oxides. The SONE reaction can be applicable to most transition metal oxides, and when utilized in a lithium-ion battery, the produced nanostructured materials are superior to their bulk counterparts and even comparable to those produced by conventional bottom-up approaches. Given its simplicity and scalability, this synthesis method could open a new avenue to the development of high-performance nanostructured electrode materials that can meet the industrial demand of cost-effectiveness for mass production. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Development and application of an ultratrace method for speciation of organotin compounds in cryogenically archived and homogenized biological materials

    Energy Technology Data Exchange (ETDEWEB)

    Point, David; Davis, W.C.; Christopher, Steven J.; Ellisor, Michael B.; Pugh, Rebecca S.; Becker, Paul R. [Hollings Marine Laboratory, National Institute of Standards and Technology, Analytical Chemistry Division, Charleston, SC (United States); Donard, Olivier F.X. [Laboratoire de Chimie Analytique BioInorganique et Environnement UMR 5034 du CNRS, Pau (France); Porter, Barbara J.; Wise, Stephen A. [National Institute of Standards and Technology, Analytical Chemistry Division, Gaithersburg, MD (United States)

    2007-04-15

    An accurate, ultra-sensitive and robust method for speciation of mono, di, and tributyltin (MBT, DBT, and TBT) by speciated isotope-dilution gas chromatography-inductively coupled plasma-mass spectrometry (SID-GC-ICPMS) has been developed for quantification of butyltin concentrations in cryogenic biological materials maintained in an uninterrupted cryo-chain from storage conditions through homogenization and bottling. The method significantly reduces the detection limits, to the low pg g{sup -1} level (as Sn), and was validated by using the European reference material (ERM) CE477, mussel tissue, produced by the Institute for Reference Materials and Measurements. It was applied to three different cryogenic biological materials - a fresh-frozen mussel tissue (SRM 1974b) together with complex materials, a protein-rich material (whale liver control material, QC03LH03), and a lipid-rich material (whale blubber, SRM 1945) containing up to 72% lipids. The commutability between frozen and freeze-dried materials with regard to spike equilibration/interaction, extraction efficiency, and the absence of detectable transformations was carefully investigated by applying complementary methods and by varying extraction conditions and spiking strategies. The inter-method results enabled assignment of reference concentrations of butyltins in cryogenic SRMs and control materials for the first time. The reference concentrations of MBT, DBT, and TBT in SRM 1974b were 0.92 {+-} 0.06, 2.7 {+-} 0.4, and 6.58 {+-} 0.19 ng g{sup -1} as Sn (wet-mass), respectively; in SRM 1945 they were 0.38 {+-} 0.06, 1.19 {+-} 0.26, and 3.55 {+-} 0.44 ng g{sup -1}, respectively, as Sn (wet-mass). In QC03LH03, DBT and TBT concentrations were 30.0 {+-} 2.7 and 2.26 {+-} 0.38 ng g{sup -1} as Sn (wet-mass). The concentration range of butyltins in these materials is one to three orders of magnitude lower than in ERM CE477. This study demonstrated that cryogenically processed and stored biological materials are

  6. Bulk heterojunction organic photovoltaic cell fabricated by the electrospray deposition method using mixed organic solvent

    Energy Technology Data Exchange (ETDEWEB)

    Fukuda, Takeshi; Takagi, Kenji; Asano, Takashi [Department of Functional Materials Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); RIKEN, 2-1 Hirosawa, Wakou-shi, Saitama 351-0198 (Japan); Honda, Zentaro; Kamata, Norihiko; Ueno, Keiji; Shirai, Hajime [Department of Functional Materials Science, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Ju, Jungmyoung; Yamagata, Yutaka; Tajima, Yusuke [RIKEN, 2-1 Hirosawa, Wakou-shi, Saitama 351-0198 (Japan)

    2011-07-15

    A high-efficiency bulk heterojunction organic photovoltaic cell (OPV) was achieved by the electrospray deposition method. The surface roughness of the P3HT:PCBM thin film can be reduced using the mixed solvent consisting of o-dichlorobenzene (o-DCB) and acetone. The effect of acetone concentration is related to its dielectric constant. Under an optimized concentration of acetone in o-DCB (20 vol%), the P3HT/PCBM active layer with a smooth surface can be formed, and the power conversion efficiency of the OPV was 1.9%. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  7. A heuristic and hybrid method for the tank allocation problem in maritime bulk shipping

    DEFF Research Database (Denmark)

    Vilhelmsen, Charlotte; Larsen, Jesper; Lusby, Richard Martin

    2016-01-01

    In bulk shipping, ships often have multiple tanks and carry multiple inhomogeneous products at a time. When operating such ships it is therefore a major challenge to decide how to best allocate cargoes to available tanks while taking into account tank capacity, safety restrictions, ship stability...... finding a feasible solution. We have developed a heuristic that can efficiently find feasible cargo allocations. Computational results show that it can solve 99 % of the considered instances within 0.4 s and all of them if allowed longer time. We have also modified an optimality based method from...... the literature. The heuristic is much faster than this modified method on the vast majority of considered instances. However, the heuristic struggles on two instances which are relatively quickly solved by the modified optimality based method. These two methods therefore complement each other nicely and so, we...

  8. A Heuristic and Hybrid Method for the Tank Allocation Problem in Maritime Bulk Shipping

    DEFF Research Database (Denmark)

    Vilhelmsen, Charlotte; Larsen, Jesper; Lusby, Richard Martin

    In bulk shipping, ships often have multiple tanks and carry multiple inhomogeneous products at a time. When operating such ships it is therefore a major challenge to decide how to best allocate cargoes to available tanks while taking into account tank capacity, safety restrictions, ship stability...... finding a feasible solution. We have developed a heuristic that can efficiently find feasible cargo allocations. Computational results show that it can solve 99% of the considered instances within 0.4 seconds and all of them if allowed longer time. We have also modified an optimality based method from...... the literature. The heuristic is much faster than this modified method on the vast majority of considered instances. However, the heuristic struggles on two instances which are relatively quickly solved by the modified optimality based method. These two methods therefore complement each other nicely and so, we...

  9. Molecular-dynamics method for the simulation of bulk-solid interfaces at high temperatures

    International Nuclear Information System (INIS)

    Lutsko, J.F.; Wolf, D.; Yip, S.; Phillpot, S.R.; Nguyen, T.

    1988-01-01

    A new method for the molecular-dynamics simulation of bulk planar interfaces at high temperatures is presented. The method uses the basic Parrinello-Rahman (constant-stress) scheme, modified for the application to inhomogeneous systems. Since our computational cell contains only one interface with two-dimensional (2D) periodic border conditions, we are able to study isolated interfaces all the way up to melting. The interaction between boundaries which may lead to their annihilation at higher temperatures, which is a problem when 3D periodic borders are applied, is thus avoided. As an application, the method is used to study the stability of a grain boundary at high temperatures. Observations on a possible connection between grain-boundary migration and ''premelting'' are discussed

  10. Speciative determination of total V and dissolved inorganic vanadium species in environmental waters by catalytic–kinetic spectrophotometric method

    Directory of Open Access Journals (Sweden)

    Ramazan Gürkan

    2017-02-01

    Full Text Available A kinetic determination of V(V as a catalyst was spectrophotometrically performed by using the indicator reaction of Gallamine blue (GB+ and bromate at pH 2.0. The reaction was followed by measuring absorbance change for a fixed-time of 3 min at 537 nm. The variables such as reagent concentration, pH, buffer concentration, ionic strength and temperature were optimized to improve the selectivity and sensitivity. Under the optimized conditions, the determination of V(V was performed in the range 1–100 μg L−1 with limits of detection and quantification of 0.31 and 0.94 μg L−1. The developed kinetic method is sufficiently sensitive, selective and simple. It was successfully applied to the speciative determination of total V and inorganic dissolved vanadium species, V(V and V(IV in environmental water samples. The oxidizing property of permanganate is used to differentiate between V(IV and V(V species. The V(IV content was found by subtracting the V(V content from those of total V. The recovery is above 95% for V(V spiked samples. Additionally, the accuracy was validated by analysis of a certified water sample, CRM TMDA-53.3, and the results were in good agreement with the certified value.

  11. A Heuristic and Hybrid Method for the Tank Allocation Problem in Maritime Bulk Shipping

    DEFF Research Database (Denmark)

    Vilhelmsen, Charlotte; Larsen, Jesper; Lusby, Richard Martin

    Many bulk ships have multiple tanks and can thereby carry multiple inhomogeneous products at a time. A major challenge when operating such ships is how to best allocate cargoes to available tanks while taking tank capacity, safety restrictions, ship stability and strength as well as other...... ship route. We have developed a randomised heuristic for eciently nding feasible allocations and computational results show that it can solve 99% of the considered instances within 0.5 seconds and all of them if allowed longer time. The heuristic is designed to work as an ecient subproblem solver...... and in such a setting with running times below e.g. 5 seconds, the heuristic clearly outperforms an earlier method by consistently solving more instances and eectively cutting 84% of the average running time. Furthermore, we have combined our heuristic with a modied version of the earlier method to derive a hybrid...

  12. An Efficient Method to Search Real-Time Bulk Data for an Information Processing System

    International Nuclear Information System (INIS)

    Kim, Seong Jin; Kim, Jong Myung; Suh, Yong Suk; Keum, Jong Yong; Park, Heui Youn

    2005-01-01

    The Man Machine Interface System (MMIS) of System-integrated Modular Advanced ReacTor (SMART) is designed with fully digitalized features. The Information Processing System (IPS) of the MMIS acquires and processes plant data from other systems. In addition, the IPS provides plant operation information to operators in the control room. The IPS is required to process bulky data in a real-time. So, it is necessary to consider a special processing method with regards to flexibility and performance because more than a few thousands of Plant Information converges on the IPS. Among other things, the processing time for searching for data from the bulk data consumes much more than other the processing times. Thus, this paper explores an efficient method for the search and examines its feasibility

  13. Flux pinning properties of impurity doped MgB2 bulks synthesized by diffusion method

    International Nuclear Information System (INIS)

    Ueda, Shinya; Shimoyama, Jun-ichi; Yamamoto, Akiyasu; Katsura, Yukari; Iwayama, Isao; Horii, Shigeru; Kishio, Kohji

    2005-01-01

    Doping effects of carbon-containing impurities on the critical current properties and microstructure were systematically studied for highly dense MgB 2 bulks prepared by the diffusion method starting from magnesium and boron which are separately packed in sealed stainless tubes. Obtained samples exhibited improved critical current density, J c , simply by an increase of effective current pass. A non-doped MgB 2 recorded almost double high J c at 20 K compared with those of the conventional porous MgB 2 bulks having ∼50% of the theoretical density, while irreversibility field, H irr , did not largely change. J c under high magnetic fields were enhanced by doping of carbon-containing impurities, such as SiC and B 4 C. Optimal doping levels of SiC and B 4 C for high critical current properties at 20 K are found to be ∼2% and 5%, respectively, as nominal carbon concentration at boron site. Difference in the optimal doping levels is originated from the difference in their reactivity

  14. A simple method of genomic DNA extraction suitable for analysis of bulk fungal strains.

    Science.gov (United States)

    Zhang, Y J; Zhang, S; Liu, X Z; Wen, H A; Wang, M

    2010-07-01

    A simple and rapid method (designated thermolysis) for extracting genomic DNA from bulk fungal strains was described. In the thermolysis method, a few mycelia or yeast cells were first rinsed with pure water to remove potential PCR inhibitors and then incubated in a lysis buffer at 85 degrees C to break down cell walls and membranes. This method was used to extract genomic DNA from large numbers of fungal strains (more than 92 species, 35 genera of three phyla) isolated from different sections of natural Ophiocordyceps sinensis specimens. Regions of interest from high as well as single-copy number genes were successfully amplified from the extracted DNA samples. The DNA samples obtained by this method can be stored at -20 degrees C for over 1 year. The method was effective, easy and fast and allowed batch DNA extraction from multiple fungal isolates. Use of the thermolysis method will allow researchers to obtain DNA from fungi quickly for use in molecular assays. This method requires only minute quantities of starting material and is suitable for diverse fungal species.

  15. Methods for analysis of the distribution and speciation of iron and zinc in the cereal grain

    DEFF Research Database (Denmark)

    Hansen, Thomas Hesselhøj

    , a novel high-throughput micro digestion method was developed, enabling the analysis of total element concentrations in small tissue fractions, such as the embryo of cereal grains. The method is based on small closed bombs that are microwaved and was validated for sample amounts between 1-20 mg using...

  16. Bulk Electrical Cable Non-Destructive Examination Methods for Nuclear Power Plant Cable Aging Management Programs

    Energy Technology Data Exchange (ETDEWEB)

    Glass, Samuel W. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Jones, Anthony M. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Fifield, Leonard S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Hartman, Trenton S. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2016-09-01

    This Pacific Northwest National Laboratory milestone report describes progress to date on the investigation of nondestructive test methods focusing particularly on bulk electrical test methods that provide key indicators of cable aging and damage. The work includes a review of relevant literature as well as hands-on experimental verification of inspection capabilities. As nuclear power plants consider applying for second, or subsequent, license renewal to extend their operating period from 60 years to 80 years, it is important to understand how the materials installed in plant systems and components will age during that time and develop aging management programs to assure continued safe operation under normal and design basis events (DBE). Normal component and system tests typically confirm the cables can perform their normal operational function. The focus of the cable test program, however, is directed toward the more demanding challenge of assuring the cable function under accident or DBE. The industry has adopted 50% elongation at break (EAB) relative to the un-aged cable condition as the acceptability standard. All tests are benchmarked against the cable EAB test. EAB, however, is a destructive test so the test programs must apply an array of other nondestructive examination (NDE) tests to assure or infer the overall set of cable’s system integrity. Assessment of cable integrity is further complicated in many cases by vendor’s use of dissimilar material for jacket and insulation. Frequently the jacket will degrade more rapidly than the underlying insulation. Although this can serve as an early alert to cable damage, direct test of the cable insulation without violating the protective jacket becomes problematic. This report addresses the range of bulk electrical NDE cable tests that are or could be practically implemented in a field-test situation with a particular focus on frequency domain reflectometry (FDR). The FDR test method offers numerous advantages

  17. Mercury speciation analysis in seafood by species-specific isotope dilution: method validation and occurrence data

    Energy Technology Data Exchange (ETDEWEB)

    Clemens, Stephanie; Guerin, Thierry [Agence Nationale de Securite Sanitaire de l' Alimentation, Laboratoire de Securite des Aliments de Maisons-Alfort, Unite des Contaminants Inorganiques et Mineraux de l' Environnement, ANSES, Maisons-Alfort (France); Monperrus, Mathilde; Donard, Olivier F.X.; Amouroux, David [IPREM UMR 5254 CNRS - Universite de Pau et des Pays de l' Adour, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, Institut des Sciences Analytiques et de Physico-chimie pour l' Environnement et les Materiaux, Pau Cedex (France)

    2011-11-15

    Methylmercury (MeHg) and total mercury (THg) in seafood were determined using species-specific isotope dilution analysis and gas chromatography combined with inductively coupled plasma mass spectrometry. Sample preparation methods (extraction and derivation step) were evaluated on certified reference materials using isotopically enriched Hg species. Solid-liquid extraction, derivation by propylation and automated agitation gave excellent accuracy and precision results. Satisfactory figures of merit for the selected method were obtained in terms of limit of quantification (1.2 {mu}g Hg kg{sup -1} for MeHg and 1.4 {mu}g Hg kg{sup -1} for THg), repeatability (1.3-1.7%), intermediate precision reproducibility (1.5% for MeHg and 2.2% for THg) and trueness (bias error less than 7%). By means of a recent strategy based on accuracy profiles ({beta}-expectation tolerance intervals), the selected method was successfully validated in the range of approximately 0.15-5.1 mg kg{sup -1} for MeHg and 0.27-5.2 mg kg{sup -1} for THg. Probability {beta} was set to 95% and the acceptability limits to {+-}15%. The method was then applied to 62 seafood samples representative of consumption in the French population. The MeHg concentrations were generally low (1.9-588 {mu}g kg{sup -1}), and the percentage of MeHg varied from 28% to 98% in shellfish and from 84% to 97% in fish. For all real samples tested, methylation and demethylation reactions were not significant, except in one oyster sample. The method presented here could be used for monitoring food contamination by MeHg and inorganic Hg in the future to more accurately assess human exposure. (orig.)

  18. A novel fast gas chromatography method for higher time resolution measurements of speciated monoterpenes in air

    Science.gov (United States)

    Jones, C. E.; Kato, S.; Nakashima, Y.; Kajii, Y.

    2014-05-01

    Biogenic emissions supply the largest fraction of non-methane volatile organic compounds (VOC) from the biosphere to the atmospheric boundary layer, and typically comprise a complex mixture of reactive terpenes. Due to this chemical complexity, achieving comprehensive measurements of biogenic VOC (BVOC) in air within a satisfactory time resolution is analytically challenging. To address this, we have developed a novel, fully automated Fast Gas Chromatography (Fast-GC) based technique to provide higher time resolution monitoring of monoterpenes (and selected other C9-C15 terpenes) during plant emission studies and in ambient air. To our knowledge, this is the first study to apply a Fast-GC based separation technique to achieve quantification of terpenes in ambient air. Three chromatography methods have been developed for atmospheric terpene analysis under different sampling scenarios. Each method facilitates chromatographic separation of selected BVOC within a significantly reduced analysis time compared to conventional GC methods, whilst maintaining the ability to quantify individual monoterpene structural isomers. Using this approach, the C9-C15 BVOC composition of single plant emissions may be characterised within a 14.5 min analysis time. Moreover, in-situ quantification of 12 monoterpenes in unpolluted ambient air may be achieved within an 11.7 min chromatographic separation time (increasing to 19.7 min when simultaneous quantification of multiple oxygenated C9-C10 terpenoids is required, and/or when concentrations of anthropogenic VOC are significant). These analysis times potentially allow for a twofold to fivefold increase in measurement frequency compared to conventional GC methods. Here we outline the technical details and analytical capability of this chromatographic approach, and present the first in-situ Fast-GC observations of 6 monoterpenes and the oxygenated BVOC (OBVOC) linalool in ambient air. During this field deployment within a suburban forest

  19. Comparison of comprehensive two-dimensional gas chromatography coupled with sulfur-chemiluminescence detector to standard methods for speciation of sulfur-containing compounds in middle distillates.

    Science.gov (United States)

    Ruiz-Guerrero, Rosario; Vendeuvre, Colombe; Thiébaut, Didier; Bertoncini, Fabrice; Espinat, Didier

    2006-10-01

    The monitoring of total sulfur content and speciation of individual sulfur-containing compounds in middle distillates is required for efficient catalyst selection and for a better understanding of the kinetics of the reactions involved in hydrotreament processes. Owing to higher resolution power and enhanced sensitivity, comprehensive two-dimensional gas chromatography (GCxGC) hyphenated to sulfur chemiluminescence detection (SCD) has recently evolved as a powerful tool for improving characterization and identification of sulfur compounds. The aim of this paper is to compare quantitatively GCxGC-SCD and various other methods commonly employed in the petroleum industry, such as X-ray fluorescence, conventional GC-SCD, and high-resolution mass spectrometry, for total sulfur content determination and speciation analysis. Different samples of middle distillates have been analyzed to demonstrate the high potential and important advantages of GCxGC-SCD for innovative and quantitative analysis of sulfur-containing compounds. More accurate and detailed results for benzothiophenes and dibenzothiophenes are presented, showing that GCxGC-SCD should become, in the future, an essential tool for sulfur speciation analysis.

  20. Bulk Synthesis and Characterization of Ti3Al Nanoparticles by Flow-Levitation Method

    Directory of Open Access Journals (Sweden)

    Shanjun Chen

    2013-01-01

    Full Text Available A novel bulk synthesis method for preparing high pure Ti3Al nanoparticles was developed by flow-levitation method (FL. The Ti and Al vapours ascending from the high temperature levitated droplet were condensed by cryogenic Ar gas under atmospheric pressure. The morphology, crystalline structure, and chemical composition of Ti3Al nanoparticles were, respectively, investigated by transmission electron microscopy, X-ray diffraction, and inductively coupled plasma atomic emission spectrometry. The results indicated that the Ti3Al powders are nearly spherical-shaped, and the particle size ranges from several nanometers to 100 nm in diameter. Measurements of the d-spacing from X-ray (XRD and electron diffraction studies confirmed that the Ti3Al nanoparticles have a hexagonal structure. A thin oxidation coating of 2-3 nm in thickness was formed around the particles after exposure to air. Based on the XPS measurements, the surface coating of the Ti3Al nanoparticles is a mixture of Al2O3 and TiO2. The production rate of Ti3Al nanoparticles was estimated to be about 3 g/h. This method has a great potential in mass production of Ti3Al nanoparticles.

  1. A Robust Analysis Method For Δ13c Signal Of Bulk Organic Matter In Speleothems

    Science.gov (United States)

    Bian, F.; Blyth, A. J.; Smith, C.; Baker, A.

    2017-12-01

    Speleothems preserve organic matter that is derived from both the surface soil and cave environments. This organic matter can be used to understand paleoclimate and paleoenvironments. However, a stable and quick micro-analysis method to measure the δ13C signals from speleothem organic matter separate from the total δ13C remains absent. And speleothem organic geochemistry is still relatively unexplored compared to inorganic geochemistry. In this research, for the organic matter analysis, bulk homogeneous power samples were obtained from one large stalagmite. These were dissolved by phosphoric acid to produce the aqueous solution. Then, the processed solution was degassed through a rotational vacuum concentrator. A liquid chromatograph was coupled to IRMS to control the oxidization and the measurement of analytes. This method is demonstrated to be robust for the analysis of speleothem d13C organic matter analysis under different preparation and instrumental settings, with the low standard deviation ( 0.2‰), and low sample consumption (<25 mg). Considering the complexity of cave environments, this method will be useful in further investigations the δ13C of entrapped organic matter and environmental controls in other climatic and ecological contexts, including the determination of whether vegetation or soil microbial activity is the dominant control on speleothem d13C of organic matter.

  2. Bulk synthesis of monodisperse magnetic FeNi3 nanopowders by flow levitation method.

    Science.gov (United States)

    Chen, Shanjun; Chen, Yan; Kang, Xiaoli; Li, Song; Tian, Yonghong; Wu, Weidong; Tang, Yongjian

    2013-10-01

    In this work, a novel bulk synthesis method for monodisperse FeNi3 nanoparticles was developed by flow levitation method (FL). The Fe and Ni vapours ascending from the high temperature levitated droplet was condensed by cryogenic Ar gas under atmospheric pressure. X-ray diffraction was used to identify and characterize the crystal phase of prepared powders exhibiting a FeNi3 phase. The morphology and size of nanopowders were observed by transmission electron microscopy (TEM). The chemical composition of the nanoparticles was determined with energy dispersive spectrometer (EDS). The results indicated that the FeNi3 permalloy powders are nearly spherical-shaped with diameter about 50-200 nm. Measurement of the magnetic property of nanopowders by a superconducting quantum interference device (SQUID, Quantum Design MPMS-7) showed a symmetric hysteresis loop of ferromagnetic behavior with coercivity of 220 Oe and saturation magnetization of 107.17 emu/g, at 293 K. At 5 K, the obtained saturation magnetization of the sample was 102.16 emu/g. The production rate of FeNi3 nanoparticles was estimated to be about 6 g/h. This method has great potential in mass production of FeNi3 nannoparticles.

  3. Rapid, Simple, and Sensitive Spectrofluorimetric Method for the Estimation of Ganciclovir in Bulk and Pharmaceutical Formulations

    Directory of Open Access Journals (Sweden)

    Garima Balwani

    2013-01-01

    Full Text Available A new, simple, rapid, sensitive, accurate, and affordable spectrofluorimetric method was developed and validated for the estimation of ganciclovir in bulk as well as in marketed formulations. The method was based on measuring the native fluorescence of ganciclovir in 0.2 M hydrochloric acid buffer of pH 1.2 at 374 nm after excitation at 257 nm. The calibration graph was found to be rectilinear in the concentration range of 0.25–2.00 μg mL−1. The limit of quantification and limit of detection were found to be 0.029 μg mL−1 and 0.010 μg mL−1, respectively. The method was fully validated for various parameters according to ICH guidelines. The results demonstrated that the procedure is accurate, precise, and reproducible (relative standard deviation <2% and can be successfully applied for the determination of ganciclovir in its commercial capsules with average percentage recovery of 101.31 ± 0.90.

  4. Predicting the effective response of bulk polycrystalline ferroelectric ceramics via improved spectral phase field methods

    Science.gov (United States)

    Vidyasagar, A.; Tan, W. L.; Kochmann, D. M.

    2017-09-01

    Understanding the electromechanical response of bulk polycrystalline ferroelectric ceramics requires scale-bridging approaches. Recent advances in fast numerical methods to compute the homogenized mechanical response of materials with heterogeneous microstructure have enabled the solution of hitherto intractable systems. In particular, the use of a Fourier-based spectral method as opposed to the traditional finite element method has gained significant interest in the homogenization of periodic microstructures. Here, we solve the periodic, electro-mechanically-coupled boundary value problem at the mesoscale of polycrystalline ferroelectrics in order to extract the effective response of barium titanate (BaTiO3) and lead zirconate titanate (PZT) under applied electric fields. Results include the effective electric hysteresis and the associated butterfly curve of strain vs. electric field for mean stress-free electric loading. Computational predictions of the 3D polycrystalline response show convincing agreement with our experimental electric cycling and strain hysteresis data for PZT-5A. In addition to microstructure-dependent effective physics, we also show how finite-difference-based approximations in the spectral solution scheme significantly reduce instability and ringing phenomena associated with spectral techniques and lead to spatial convergence with h-refinement, which have been major challenges when modeling high-contrast systems such as polycrystals.

  5. Speciation Analysis of Radionuclides in the Environment - NSK-B SPECIATION project report 2009

    DEFF Research Database (Denmark)

    Hou, Xiaolin; Aldahan, Ala; Possnert, Göran

    . Speciation of radionuclides in soils and sediments includes: Sequential extraction of radionuclides in sediments and of trace elements in soil samples. Sequential extraction of radionuclides in aerosols and particles has also been performed. Further-more, sorption experiments have been performed......, sediments, particles); and (3) Intercomparison excise for speciation analysis of radionu-clides in soil and sediment. This report summarizes the work completed in the project partners’ laboratories, Method developments include: Development of an rapid and in-suit separation method for the speciation...... analysis of 129I in seawater samples; Development of a simple method for the speciation analysis of 129I in fresh water and seawater samples; Development of an on-line HPLC-ICP-MS method for the direct speciation analysis of 127I in water and leachate samples; Speciation of radionuclides in water includes...

  6. Development of a definitive method for iodine speciation in aquatic systems

    International Nuclear Information System (INIS)

    Reifenhaeuser, C.; Heumann, K.G.

    1990-01-01

    A definitive method of isotope dilution mass spectrometry (IDMS) was developed to determine four different iodine species in aquatic systems (iodide, iodate and two organoiodine compounds: one of the organic species is chromatographically elutable from a column filled with an anion exchanger resin, the other one is not). The iodine species were analysed after the isotope dilution step with an enriched 129 I spike and after their chromatographic separation. The total iodine concentration was measured after decomposition of organic compounds in the aquatic system by UV irradiation. Different types of natural water samples (river water, water of a pond, moorland lake water) were analysed and important water parameters like pH-value, redox potential, oxygen content and dissolved organic carbon were measured for each of these samples. The total iodine concentration in the different samples differed only slightly in the range of 2-7 μg/l. In most of the moorland lake water samples only the two organoiodine species could be detected. In these samples the concentration of iodide and iodate was less than the detection limit of 0.5 μg/l and 0.1 μg/l, respectively. On the other hand, all four iodine species could be determined in most of the river water samples. Positive correlations were found for the oxygen content of the water samples and the iodate concentration as well as for the redox potential and the anionic organoiodine compound. (orig.)

  7. The speciation of iodine in the environment

    International Nuclear Information System (INIS)

    Bulman, R.A.

    1986-01-01

    The speciation of iodine in the environment is discussed under the following topics: (i) sea surface to atmosphere, (ii) chemistry in bulk seawater, (iii) iodine in rocks, (iv) iodine in soils, (v) iodine in plants and (vi) iodine in solidified wastes. (author)

  8. Spectrophotometric and spectrofluorimetric methods for the determination of saxagliptin and vildagliptin in bulk and pharmaceutical preparations

    Directory of Open Access Journals (Sweden)

    Marwa S. Moneeb

    2013-12-01

    Full Text Available New simple and sensitive spectrophotometric and spectrofluorimetric methods have been developed and validated for the determination of saxagliptin (SAX and vildagliptin (VDG in bulk and pharmaceutical preparations. The spectrophotometric methods were based on derivatization of the investigated drugs with two reagents: 1,2-naphthoquinone-4-sulfonic acid sodium salt (NQS and 4-chloro-7-nitrobenzofurazan (NBD-Cl. For further increase in the sensitivity, the D1 spectra of the reactions products were also recorded. For NQS reaction, Beer’s law was obeyed over the ranges of 5–30 and 7–45 μg mL−1 for the absorbance readings; and 3–32 and 5–50 μg mL−1 for the derivative readings of SAX and VDG, respectively. For NBD-Cl reaction, Beer’s law was obeyed over the ranges of 3–20 and 4.5–35 μg mL−1 for the absorbance readings; and 1.5–25 and 2.5–40 μg mL−1 for the derivative readings of SAX and VDG, respectively. Spectrofluorimetric methods were developed based on the fact that the derivatized investigated drugs with NBD-Cl reagent are highly fluorescent products. The fluorescence concentration plots were linear over the ranges of 0.02–0.25 and 0.03–0.37 μg mL−1 for SAX and VDG, respectively. The fluorescence measurement enabled the detection of SAX and VDG at concentrations of about 3 and 7 ng mL−1, respectively. The proposed methods have been validated and successfully applied to the determination of the investigated drugs in their pharmaceutical preparations. The results obtained were statistically compared to those obtained from reference methods.

  9. Uranium theoretical speciation for drinking water from private drilled wells in Sweden – Implications for choice of removal method

    International Nuclear Information System (INIS)

    Norrström, Ann Catrine; Löv, Åsa

    2014-01-01

    Highlights: • Neutral charge uranium complexes dominated in the pH range 6.7–7.8. • The Ca concentration influence which calcium-UO 2 carbonate complexes was formed. • In the acidic pH range several different U complexes can comprise a large fraction of total complexes. • It is crucial to include all relevant chemical compounds in the model. • Before removal method is selected, some crucial parameters should be measured. - Abstract: Elevated concentrations of uranium (U) from natural sources have been measured in drinking water from private drilled wells in Sweden and many other countries world-wide. Although U is a radioactive element, radioactivity is not the main concern, but rather chemical toxicity, e.g. kidney damage. Uranium chemistry is complex and U in water has a very high tendency to form complexes with other compounds. Since speciation is crucial for the properties of U, and therefore the removal efficiency, this study determined theoretical U species in drinking water from private drilled wells using the geochemical model Visual MINTEQ. The drinking water samples used in modelling were from two datasets: (1) 76 water samples selected from a previous survey of 722 wells; and (2) samples of drinking water from 21 private wells sampled in May 2013. The results showed that neutrally charged U complexes dominated in the pH range 6.7–7.8, which is common in private drilled wells. This has important implications for removal method, since charge is an important factor for U removal efficiency. In the alkaline pH range, one of two calcium-UO 2 carbonate complexes dominated and calcium (Ca) concentration proved to be a key factor determining the Ca-UO 2 carbonate complex formed: the neutral Ca 2 UO 2 (CO 3 ) 3 0 (aq) or the negative CaUO 2 (CO 3 ) 3 2− . Complexes with organic carbon (C) varied greatly in the acidic range, indicating that it is crucial to measure organic C content in the water since it is critical for the dissolved organic matter

  10. Repetitive forging (RF) using inclined punches as a new bulk severe plastic deformation method

    Energy Technology Data Exchange (ETDEWEB)

    Babaei, A. [Department of Mechanical Engineering, University College of Engineering, University of Tehran, Tehran 11155-4563 (Iran, Islamic Republic of); Faraji, G., E-mail: ghfaraji@ut.ac.ir [Department of Mechanical Engineering, University College of Engineering, University of Tehran, Tehran 11155-4563 (Iran, Islamic Republic of); Department of Engineering Design and Manufacture, University of Malaya, 50603 Kuala Lumpur (Malaysia); Mashhadi, M.M. [Department of Mechanical Engineering, University College of Engineering, University of Tehran, Tehran 11155-4563 (Iran, Islamic Republic of); Hamdi, M. [Department of Engineering Design and Manufacture, University of Malaya, 50603 Kuala Lumpur (Malaysia)

    2012-12-15

    A new bulk severe plastic deformation method based on repetitive forging (RF) using inclined punches is proposed. This process consists of two half cycles. In the first half cycle, a square cross section deforms to parallelogram by forging with two inclined punches, and the parallelogram cross section is forged back to square using two flat punches in the second half cycle. This method was applied to commercially pure copper and significant grain refinement was achieved after four passes of RF. The results showed that significant improvement in the mechanical properties was obtained. Notable increase of yield and ultimate strengths corresponding to 358 MPa and 381 MPa after four passes of RF from the initial values of 121 MPa and 230.5 MPa is detectable. Microhardness increases to about 100 Hv after four passes of RF from the initial value of 53 Hv. Finite element (FE) results illustrate that RF is able to impose extremely high plastic strains to the materials. In the RF process, the processed samples have the same dimensions and geometry as those of the initial sample without any waste material and there is no need for back pressure.

  11. Spectrophotometric methods for the simultaneous estimation of ofloxacin and tinidazole in bulk and pharmaceutical dosage form

    Directory of Open Access Journals (Sweden)

    Kareti Srinivasa Rao

    2011-01-01

    Full Text Available Aim: This work deals with the simultaneous estimation of Ofloxacin (OFL and Tinidazole (TNZ in in bulk and pharmaceutical dosage form, without prior separation, by three different techniques (Simultaneous equation, Absorbance ratio method and First order derivative method. Materials and Methods: The present work was carried out on Shimadzu electron UV1800 double beam UV-Visible spectrophotometer. The absorption spectra of reference and test solutions were carried out in 1 cm matched quartz cell over the range of 200 - 400 nm. Standard gift sample of OFL and TNZ obtain from Torrent pharmaceuticals Ltd., Baddi, Himachal Pradesh. Combined OFL and TNZ tablets were purchased from local market. Methanol from Merck Ltd and distilled water are used as solvent. Results: The first method is the application of simultaneous equation. Where the linearity ranges for OFL and TNZ were 5-30 μg/ml and 10-50 μg/ml respectively. The second method is the determination of ratio of absorbance at 278nm, the maximum absorption of TNZ and isobestic wavelength 283 nm, the linearity ranges for OFL and TNZ were 5-30 μg/ml and 10-50μg/ml respectively. The third method is the first order derivative method, where the linearity ranges for OFL and TNZ were 5-30 μg/ml and 10-50 μg/ml respectively. The results of the analysis have been validated statistically and by recovery studies, where the percentage recovery was found to be 100.9±0.49 and 97.30±0.20 using the simultaneous equation method, 98±0.45 and 100.4±0.48 using the graphical absorbance ratio method and 99.10±0.40 and 84.70±0.70 using first derivative method, for OFL and TNZ respectively. Conclusions: The proposed procedures are rapid, simple, require no preliminary separation steps and can be used for routine analysis of both drugs in quality control laboratories.

  12. Comparison and limitations of three different bulk etch rate measurement methods used for gamma irradiated PM-355 detectors

    Energy Technology Data Exchange (ETDEWEB)

    Fazal-ur-Rehman E-mail: fazalr@kfupm.edu.sa; Abu-Jarad, F.; Al-Jarallah, M.I.; Farhat, M

    2001-06-01

    Samples of Nuclear Track Detectors (PM-355) were exposed to high gamma doses from 1x10{sup 5} Gy (10 Mrad) up to 1.2x10{sup 6} Gy (120 Mrad) at an incremental dose of 1x10{sup 5} Gy (10 Mrad). The gamma source was a 9.03 PBq (244 kCi) Co-60 source used for sterilization of medical syringes. The bulk etch rate (V{sub b}) was measured for various high gamma doses by three different methods: 1--thickness change method; 2--mass change method; 3--fission track diametric method. The study gives a comparison and limitations of these three methods used for bulk etch rate measurements in the detectors as a function of high gamma doses. The track etch rate (V{sub t}) and the sensitivity (V) of the detector were also measured using the fission track diametric method. It was observed that V{sub b} increases with the increase of the gamma absorbed dose at a fixed etching time in each bulk etch measuring method. The bulk etch rate decreases exponentially with the etching time at a fixed gamma absorbed dose in all three methods. The thickness change and mass change methods have successfully been applied to measure V{sub b} at higher gamma doses up to 1.2x10{sup 6} Gy (120 Mrad). The bulk etch rate determined by the mass change and thickness change methods was almost the same at a certain gamma dose and etching time whereas it was quite low in the case of the fission track diametric method due to its limitations at higher doses. Also in this method it was not possible to measure the fission fragment track diameters at higher doses due to the quick disappearance of the fission tracks and therefore the V{sub b} could not be estimated at higher gamma doses.

  13. 40 CFR Appendix E to Subpart E of... - Interim Method of the Determination of Asbestos in Bulk Insulation Samples

    Science.gov (United States)

    2010-07-01

    ... interpretation of point count data 3 is available. This method is applicable to all bulk samples of friable... matrices are not currently available. Data obtained for samples containing a single asbestos type in a... and characterization of fibrous and nonfibrous amphiboles for analytical methods development, pp. 295...

  14. Speciation analysis of radionuclides in the environment. NKS-B speciation project report 2007

    Energy Technology Data Exchange (ETDEWEB)

    Xiaolin Hou (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Aldahan, A. (Uppsala Univ., Dept. of Earth Science, Uppsala (Sweden)); Possnert, G. (Uppsala Univ., Tandem Lab., Uppsala (Sweden)); Lujaniene, G. (Institute of Physics, Vilnius (Lithuania)); Lehto, J. (Univ. of Helsinki, Dept. of Chemistry, Helsinki (Finland)); Salbu, B. (Norwegian Univ. of Life Sciences (UMB), AAs (Norway))

    2008-07-15

    This report describes the work carried out under the NUK-B project SPECIATION 2007. In 2007, the project partners had two meeting in April and November, organized a NUK seminar on speciation and hot particles. SPECIATION 2007 t mainly focused on two issues on speciation (1) further development of speciation methods for radionuclides, and (2) investigation of speciation of radionuclides in environment. The report summarized the work done in partners labs, which includes: (1) Further development on the speciation of 129I and 127I in water samples; (2) Speciation method for 129I and 127I in air; (3) Dynamic system for fractionation of Pu and Am in soil and sediment; (4) Investigation on Re-absorption of Pu during the fractionation of Pu in soil and sediment; (5) Speciation of 129I in North Sea surface water; (6) Partition of 137Cs and 129I in the Nordic lake sediment, pore-water and lake water; (7) Sequential extraction of Pu in soil, sediment and concrete samples, (8) Pu sorption to Mn and Fe oxides in the geological materials, (10) Investigation of the adsorbed species of lanthanides and actinides on clays surfaces. In addition, two review articles on the speciation of plutonium and iodine in environmental are planned to be submitted to an international journal for publication. (au)

  15. Speciation analysis of radionuclides in the environment. NKS-B speciation project report 2007

    International Nuclear Information System (INIS)

    Hou, Xiaolin; Aldahan, A.; Possnert, G.; Lujaniene, G.; Lehto, J.; Salbu, B.

    2008-07-01

    This report describes the work carried out under the NUK-B project SPECIATION 2007. In 2007, the project partners had two meeting in April and November, organized a NUK seminar on speciation and hot particles. SPECIATION 2007 t mainly focused on two issues on speciation (1) further development of speciation methods for radionuclides, and (2) investigation of speciation of radionuclides in environment. The report summarized the work done in partners labs, which includes: (1) Further development on the speciation of 129I and 127I in water samples; (2) Speciation method for 129I and 127I in air; (3) Dynamic system for fractionation of Pu and Am in soil and sediment; (4) Investigation on Re-absorption of Pu during the fractionation of Pu in soil and sediment; (5) Speciation of 129I in North Sea surface water; (6) Partition of 137Cs and 129I in the Nordic lake sediment, pore-water and lake water; (7) Sequential extraction of Pu in soil, sediment and concrete samples, (8) Pu sorption to Mn and Fe oxides in the geological materials, (10) Investigation of the adsorbed species of lanthanides and actinides on clays surfaces. In addition, two review articles on the speciation of plutonium and iodine in environmental are planned to be submitted to an international journal for publication. (au)

  16. STABILIZATION OF DEWATERED SEWAGE SLUDGE BY AEROBIC COMPOSTING METHOD: USING SAWDUST AS BULKING AGENTS

    Directory of Open Access Journals (Sweden)

    A PARVARESH

    2002-12-01

    Full Text Available Introduction. Sludge production from municipal wastewater treatment plants should have quality standards before disposal in to the environment. Environmental specialists classified sewage sludge as a hazardous waste because of high organic compounds and pathogenic microorganisms. They belive that sewage should be stabilized before disposal and so composting of sewage sludge is an effective and economical method to stabilize. Sewage sludge compost could be used to improve soil structure and enrich the soil with nutrients. Methods. To evaluate the optimum conditions of aerobic compost, the mixture of dewatered sewage sludge from Isfahan municipal waste water treatment plant and sawdust as bulking agent were used. Pilot scale study were performed in Isfahan municipal waste water treatment plant. To perform this research project, the dewatered sewage sludge with humidity between 78 to 82 percent were mixed with sawdust. Turning over method of the piles with one week interval were applied to aerate the mixture. Temperature of the piles were monitored at different depths daily. Other parameters such as N, G, organic matters and pH were determined weekly. Total and fecal coli form, and salmonella were determined at the beginning and end of the composting process, also heavy metals were measured at the same time. Results. The results of this study showed that after days, temperature of the mixture reached up to 55 G, and were stabled for 15 days. Humidity, organic matter, organic carbon and GIN ratio of the mixture decreased over the period of the study, due to increasing the temperature. Also organic matter and humidity mainly decreased in thermofilic phase. The number of total and fecal coliform and also salmonella decreased to A class standards of US.EPA at the end of the operation. Discussion. The results of the study also showed that, this type of composting method is reliable, and simple to schedule, with high flexibility and low odor

  17. Comparison of two experimental speciation methods with a theoretical approach to monitor free and labile Cd fractions in soil solutions

    International Nuclear Information System (INIS)

    Parat, C.; Cornu, J.-Y.; Schneider, A.; Authier, L.; Sapin-Didier, V.; Denaix, L.; Potin-Gautier, M.

    2009-01-01

    This work focused on the suitability of two techniques to monitor cadmium speciation in soil solutions collected during a 7-day incubation of a contaminated soil. Anodic stripping voltammetry (ASV) and ion exchange were performed on soil solutions collected daily and results were compared with calculations obtained with the speciation software Visual MINTEQ. The electrochemically labile Cd fraction was greater than the exchange-estimated free Cd fraction during the first 6 days, after which it decreased sharply during the last 2 days to reach values close to the exchange-estimated free Cd fraction. Further investigations showed that the increase in pH was mainly responsible for the reduction. However, calculations performed with Visual MINTEQ software clearly demonstrated that a change in the nature of organic matter and/or its complexing capacity also needed to be taken into consideration.

  18. Determining uranium speciation in contaminated soils by molecular spectroscopic methods: Examples from the Uranium in Soils Integrated Demonstration

    International Nuclear Information System (INIS)

    Allen, P.G.; Berg, J.M.; Chisholm-Brause, C.J.; Conradson, S.D.; Donohoe, R.J.; Morris, D.E.; Musgrave, J.A.; Tait, C.D.

    1994-01-01

    The US Department of Energy's former uranium production facility located at Fernald, OH (18 mi NW of Cincinnati) is the host site for an Integrated Demonstration for remediation of uranium-contaminated soils. A wide variety of source terms for uranium contamination have been identified reflecting the diversity of operations at the facility. Most of the uranium contamination is contained in the top ∼1/2 m of soil, but uranium has been found in perched waters indicating substantial migration. In support of the development of remediation technologies and risk assessment, we are conducting uranium speciation studies on untreated and treated soils using molecular spectroscopies. Untreated soils from five discrete sites have been analyzed. We have found that ∼80--90% of the uranium exists as hexavalent UO 2 2+ species even though many source terms consisted of tetravalent uranium species such as UO 2 . Much of the uranium exists as microcrystalline precipitates (secondary minerals). There is also clear evidence for variations in uranium species from the microscopic to the macroscopic scale. However, similarities in speciation at sites having different source terms suggest that soil and groundwater chemistry may be as important as source term in defining the uranium speciation in these soils. Characterization of treated soils has focused on materials from two sites that have undergone leaching using conventional extractants (e.g., carbonate, citrate) or novel chelators such as Tiron. Redox reagents have also been used to facilitate the leaching process. Three different classes of treated soils have been identified based on the speciation of uranium remaining in the soils. In general, the effective treatments decrease the total uranium while increasing the ratio of U(IV) to U(VI) species

  19. Power System Decomposition for Practical Implementation of Bulk-Grid Voltage Control Methods

    Energy Technology Data Exchange (ETDEWEB)

    Vallem, Mallikarjuna R.; Vyakaranam, Bharat GNVSR; Holzer, Jesse T.; Elizondo, Marcelo A.; Samaan, Nader A.

    2017-10-19

    Power system algorithms such as AC optimal power flow and coordinated volt/var control of the bulk power system are computationally intensive and become difficult to solve in operational time frames. The computational time required to run these algorithms increases exponentially as the size of the power system increases. The solution time for multiple subsystems is less than that for solving the entire system simultaneously, and the local nature of the voltage problem lends itself to such decomposition. This paper describes an algorithm that can be used to perform power system decomposition from the point of view of the voltage control problem. Our approach takes advantage of the dominant localized effect of voltage control and is based on clustering buses according to the electrical distances between them. One of the contributions of the paper is to use multidimensional scaling to compute n-dimensional Euclidean coordinates for each bus based on electrical distance to perform algorithms like K-means clustering. A simple coordinated reactive power control of photovoltaic inverters for voltage regulation is used to demonstrate the effectiveness of the proposed decomposition algorithm and its components. The proposed decomposition method is demonstrated on the IEEE 118-bus system.

  20. A new method for evaluating structural stability of bulk metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Lei; Jia, Haoling [Key Laboratory of Aerospace Materials and Performance, Ministry of Education, School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Xie, Shenghui; Zeng, Xierong [College of Materials Science and Engineering, Shenzhen University and Shenzhen Key Laboratory of Special Functional Materials, ShenZhen 518060 (China); Zhang, Tao [Key Laboratory of Aerospace Materials and Performance, Ministry of Education, School of Materials Science and Engineering, Beihang University, Beijing 100191 (China); Ma, Chaoli, E-mail: machaoli@buaa.edu.c [Key Laboratory of Aerospace Materials and Performance, Ministry of Education, School of Materials Science and Engineering, Beihang University, Beijing 100191 (China)

    2010-08-15

    This paper proposed a new method for evaluating the structural stability of bulk metallic glasses (BMGs) based on dilatometric measurements. During heating in the dilatometric experiments, the BMGs expanded continuously with increasing temperature. When the temperature reached the glass transition temperature (T{sub g}), viscous shrinkage occurred due to the viscosity of material becoming lower. Since the inhomogeneous nature of the metallic glasses at atomic level, the processes of rigid expansion and the viscous shrinkage co-exist in a certain temperature region. The expansion stopped completely at a temperature (named T{sub p} here) beyond T{sub g}. The values of the temperature region, {Delta}T{sub gp} = T{sub p} - T{sub g}, and the corresponding time interval ({Delta}t{sub gp}) and the activation energy (E{sub p}) corresponding to the expansion processes, are the reflection of the structural stability of BMGs. Investigating the co-existing processes kinetically and thermodynamically, we can make an insight into the structural stability of metallic glasses. Based on this idea, the thermal expansion behaviors of Mg-, Pd-, Zr-, Ti- and Fe-based BMG were studied, and their structural stability was evaluated by the parameters of {Delta}T{sub gp}, {Delta}t{sub gp} and E{sub p}.

  1. Separation/Preconcentration and Speciation Analysis of Trace Amounts of Arsenate and Arsenite in Water Samples Using Modified Magnetite Nanoparticles and Molybdenum Blue Method

    Directory of Open Access Journals (Sweden)

    Mohammad Ali Karimi

    2014-01-01

    Full Text Available A new, simple, and fast method for the separation/preconcentration and speciation analysis of arsenate and arsenite ions using cetyltrimethyl ammonium bromide immobilized on alumina-coated magnetite nanoparticles (CTAB@ACMNPs followed by molybdenum blue method is proposed. The method is based on the adsorption of arsenate on CTAB@ACMNPs. Total arsenic in different samples was determined as As(V after oxidation of As(III to As(V using potassium permanganate. The arsenic concentration has been determined by UV-Visible spectrometric technique based on molybdenum blue method and amount of As(III was calculated by subtracting the concentration of As(V from total arsenic concentration. MNPs and ACMNPs were characterized by VSM, XRD, SEM, and FT-IR spectroscopy. Under the optimal experimental conditions, the preconcentration factor, detection limit, linear range, and relative standard deviation (RSD of arsenate were 175 (for 350 mL of sample solution, 0.028 μg mL−1, 0.090–4.0 μg mL−1, and 2.8% (for 2.0 μg mL−1, n=7, respectively. This method avoided the time-consuming column-passing process of loading large volume samples in traditional SPE through the rapid isolation of CTAB@ACMNPs with an adscititious magnet. The proposed method was successfully applied to the determination and speciation of arsenic in different water samples and suitable recoveries were obtained.

  2. Three-dimensional Finite Elements Method simulation of Total Ionizing Dose in 22 nm bulk nFinFETs

    Energy Technology Data Exchange (ETDEWEB)

    Chatzikyriakou, Eleni, E-mail: ec3g12@soton.ac.uk; Potter, Kenneth; Redman-White, William; De Groot, C.H.

    2017-02-15

    Highlights: • Simulation of Total Ionizing Dose using the Finite Elements Method. • Carrier generation, transport and trapping in the oxide. • Application in three-dimensional bulk FinFET model of 22 nm node. • Examination of trapped charge in the Shallow Trench Isolation. • Trapped charge dependency of parasitic transistor current. - Abstract: Finite Elements Method simulation of Total Ionizing Dose effects on 22 nm bulk Fin Field Effect Transistor (FinFET) devices using the commercial software Synopsys Sentaurus TCAD is presented. The simulation parameters are extracted by calibrating the charge trapping model to experimental results on 400 nm SiO{sub 2} capacitors irradiated under zero bias. The FinFET device characteristics are calibrated to the Intel 22 nm bulk technology. Irradiation simulations of the transistor performed with all terminals unbiased reveal increased hardness up to a total dose of 1 MRad(SiO{sub 2}).

  3. Speciation analysis of radionuclides in the environment - NSK-B SPECIATION project report 2009

    International Nuclear Information System (INIS)

    Hou, X.; Aldahan, A.; Possnert, G.; Lujaniene, G.; Lehto, J.; Skipperud, L.; Lind, O.C.; Salbu, B.

    2009-10-01

    The second stage of the NKS-B project SPECIATION was complemented in 2008-2009, which mainly focus on three aspects: (1) Further improvement and development of methods for speciation analysis of radionuclides; (2) Investigation of speciation of some radionuclides in the environment (water, sediments, particles); and (3) Intercomparison excise for speciation analysis of radionuclides in soil and sediment. This report summarizes the work completed in the project partners' laboratories. Method developments include: Development of an rapid and in-suit separation method for the speciation analysis of 129I in seawater samples; Development of a simple method for the speciation analysis of 129I in fresh water and seawater samples; Development of an on-line HPLC-ICP-MS method for the direct speciation analysis of 127I in water and leachate samples; Speciation of radionuclides in water includes: Speciation of 129I and 127I in time-series precipitation samples collected in Denmark 2001-2006 and its application for the investigation of geochemistry and atmospheric chemistry of iodine, Speciation of radionuclides in Ob and Yenisey Rivers, and Speciation of 129I and 127I in Lake Heimdalen water. Speciation of radionuclides in soils and sediments includes: Sequential extraction of radionuclides in sediments and of trace elements in soil samples. Sequential extraction of radionuclides in aerosols and particles has also been performed. Furthermore, sorption experiments have been performed to investigate the association of Pu, Am and Cs with different geological materials. The intercomparison exercises included sequential extraction of Pu, 137Cs, U, Th, and 129I in one soil and one sediment standard reference materials (NIST-4354, IAEA-375) and Pu in sediment collected from the Lake Heimdalen, Norway. (author)

  4. Speciation analysis of radionuclides in the environment - NSK-B SPECIATION project report 2009

    Energy Technology Data Exchange (ETDEWEB)

    Hou, X. (Technical Univ. of Denmark, Risoe National Lab. for Sustainable Energy, Roskilde (Denmark)); Aldahan, A. (Uppsala Univ., Dept. of Earth Science (Sweden)); Possnert, G. (Uppsala Univ., Tandem Lab. (Sweden)); Lujaniene, G. (Univ. of Helsinki, Lab. of Radiochemistry (Finland)); Lehto, J. (Institute of Physics (Lithuania)); Skipperud, L.; Lind, O.C.; Salbu, B. (Norwegian Univ. of Life Sciences, Isotope Lab., AAs (Norway))

    2009-10-15

    The second stage of the NKS-B project SPECIATION was complemented in 2008-2009, which mainly focus on three aspects: (1) Further improvement and development of methods for speciation analysis of radionuclides; (2) Investigation of speciation of some radionuclides in the environment (water, sediments, particles); and (3) Intercomparison excise for speciation analysis of radionuclides in soil and sediment. This report summarizes the work completed in the project partners' laboratories. Method developments include: Development of an rapid and in-suit separation method for the speciation analysis of 129I in seawater samples; Development of a simple method for the speciation analysis of 129I in fresh water and seawater samples; Development of an on-line HPLC-ICP-MS method for the direct speciation analysis of 127I in water and leachate samples; Speciation of radionuclides in water includes: Speciation of 129I and 127I in time-series precipitation samples collected in Denmark 2001-2006 and its application for the investigation of geochemistry and atmospheric chemistry of iodine, Speciation of radionuclides in Ob and Yenisey Rivers, and Speciation of 129I and 127I in Lake Heimdalen water. Speciation of radionuclides in soils and sediments includes: Sequential extraction of radionuclides in sediments and of trace elements in soil samples. Sequential extraction of radionuclides in aerosols and particles has also been performed. Furthermore, sorption experiments have been performed to investigate the association of Pu, Am and Cs with different geological materials. The intercomparison exercises included sequential extraction of Pu, 137Cs, U, Th, and 129I in one soil and one sediment standard reference materials (NIST-4354, IAEA-375) and Pu in sediment collected from the Lake Heimdalen, Norway. (author)

  5. Iodine speciation in coastal and inland bathing waters and seaweeds extracts using a sequential injection standard addition flow-batch method.

    Science.gov (United States)

    Santos, Inês C; Mesquita, Raquel B R; Bordalo, Adriano A; Rangel, António O S S

    2015-02-01

    The present work describes the development of a sequential injection standard addition method for iodine speciation in bathing waters and seaweeds extracts without prior sample treatment. Iodine speciation was obtained by assessing the iodide and iodate content, the two inorganic forms of iodine in waters. For the determination of iodide, an iodide ion selective electrode (ISE) was used. The indirect determination of iodate was based on the spectrophotometric determination of nitrite (Griess reaction). For the iodate measurement, a mixing chamber was employed (flow batch approach) to explore the inherent efficient mixing, essential for the indirect determination of iodate. The application of the standard addition method enabled detection limits of 0.14 µM for iodide and 0.02 µM for iodate, together with the direct introduction of the target water samples, coastal and inland bathing waters. The results obtained were in agreement with those obtained by ICP-MS and a colorimetric reference procedure. Recovery tests also confirmed the accuracy of the developed method which was effectively applied to bathing waters and seaweed extracts. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Electrical method for the measurements of volume averaged electron density and effective coupled power to the plasma bulk

    Science.gov (United States)

    Henault, M.; Wattieaux, G.; Lecas, T.; Renouard, J. P.; Boufendi, L.

    2016-02-01

    Nanoparticles growing or injected in a low pressure cold plasma generated by a radiofrequency capacitively coupled capacitive discharge induce strong modifications in the electrical parameters of both plasma and discharge. In this paper, a non-intrusive method, based on the measurement of the plasma impedance, is used to determine the volume averaged electron density and effective coupled power to the plasma bulk. Good agreements are found when the results are compared to those given by other well-known and established methods.

  7. New method for introducing nanometer flux pinning centers into single domain YBCO bulk superconductors

    International Nuclear Information System (INIS)

    Yang, W.M.; Wang, Miao

    2013-01-01

    Highlights: • Single domain YBCO bulks with Bi 2 O 3 additions fabricated by TSIG process. • Nanoscale Y 2 Ba 4 CuBiOx(YBi2411) particles introduced by Bi 2 O 3 additions. • The YBi2411 particles are about 150 nm, can act as effective flux pinning centers. • The optimal addition of Bi 2 O 3 is 0.7wt% to achieve higher levitation force. • The result is helpful to improve the quality of REBCO bulk superconductors. -- Abstract: Single domain YBCO superconductors with different additions of Bi 2 O 3 have been fabricated by top seeded infiltration and growth process (TSIG). The effect of Bi 2 O 3 additions on the growth morphology, microstructure and levitation force of the YBCO bulk superconductor has been investigated. The results indicate that single domain YBCO superconductors can be fabricated with the additions of Bi 2 O 3 less than 2 wt%; Bi 2 O 3 can be reacted with Y 2 BaCuO 5 and liquid phase and finally form Y 2 Ba 4 CuBiO x (YBi2411) nanoscale particles; the size of the YBi2411 particles is about 100 nm, which can act as effective flux pinning centers. It is also found that the levitation force of single domain YBCO bulks is increasing from 13 N to 34 N and decreasing to 11 N with the increasing of Bi 2 O 3 addition from 0.1 wt% to 0.7 wt% and 2 wt%. This result is helpful for us to improve the physical properties of REBCO bulk superconductors

  8. A Semi-Analytical Extraction Method for Interface and Bulk Density of States in Metal Oxide Thin-Film Transistors.

    Science.gov (United States)

    Chen, Weifeng; Wu, Weijing; Zhou, Lei; Xu, Miao; Wang, Lei; Ning, Honglong; Peng, Junbiao

    2018-03-11

    A semi-analytical extraction method of interface and bulk density of states (DOS) is proposed by using the low-frequency capacitance-voltage characteristics and current-voltage characteristics of indium zinc oxide thin-film transistors (IZO TFTs). In this work, an exponential potential distribution along the depth direction of the active layer is assumed and confirmed by numerical solution of Poisson's equation followed by device simulation. The interface DOS is obtained as a superposition of constant deep states and exponential tail states. Moreover, it is shown that the bulk DOS may be represented by the superposition of exponential deep states and exponential tail states. The extracted values of bulk DOS and interface DOS are further verified by comparing the measured transfer and output characteristics of IZO TFTs with the simulation results by a 2D device simulator ATLAS (Silvaco). As a result, the proposed extraction method may be useful for diagnosing and characterising metal oxide TFTs since it is fast to extract interface and bulk density of states (DOS) simultaneously.

  9. A Semi-Analytical Extraction Method for Interface and Bulk Density of States in Metal Oxide Thin-Film Transistors

    Directory of Open Access Journals (Sweden)

    Weifeng Chen

    2018-03-01

    Full Text Available A semi-analytical extraction method of interface and bulk density of states (DOS is proposed by using the low-frequency capacitance–voltage characteristics and current–voltage characteristics of indium zinc oxide thin-film transistors (IZO TFTs. In this work, an exponential potential distribution along the depth direction of the active layer is assumed and confirmed by numerical solution of Poisson’s equation followed by device simulation. The interface DOS is obtained as a superposition of constant deep states and exponential tail states. Moreover, it is shown that the bulk DOS may be represented by the superposition of exponential deep states and exponential tail states. The extracted values of bulk DOS and interface DOS are further verified by comparing the measured transfer and output characteristics of IZO TFTs with the simulation results by a 2D device simulator ATLAS (Silvaco. As a result, the proposed extraction method may be useful for diagnosing and characterising metal oxide TFTs since it is fast to extract interface and bulk density of states (DOS simultaneously.

  10. High Quality, Low Cost Bulk Gallium Nitride Substrates Grown by the Electrochemical Solution Growth Method

    Energy Technology Data Exchange (ETDEWEB)

    Seacrist, Michael [SunEdison Inc., St. Peters, MO (United States)

    2017-08-15

    The objective of this project was to develop the Electrochemical Solution Growth (ESG) method conceived / patented at Sandia National Laboratory into a commercially viable bulk gallium nitride (GaN) growth process that can be scaled to low cost, high quality, and large area GaN wafer substrate manufacturing. The goal was to advance the ESG growth technology by demonstrating rotating seed growth at the lab scale and then transitioning process to prototype commercial system, while validating the GaN material and electronic / optical device quality. The desired outcome of the project is a prototype commercial process for US-based manufacturing of high quality, large area, and lower cost GaN substrates that can drive widespread deployment of energy efficient GaN-based power electronic and optical devices. In year 1 of the project (Sept 2012 – Dec 2013) the overall objective was to demonstrate crystalline GaN growth > 100um on a GaN seed crystal. The development plan included tasks to demonstrate and implement a method for purifying reagent grade salts, develop the reactor 1 process for rotating seed Electrochemical Solution Growth (ESG) of GaN, grow and characterize ESG GaN films, develop a fluid flow and reaction chemistry model for GaN film growth, and design / build an improved growth reactor capable of scaling to 50mm seed diameter. The first year’s project objectives were met in some task areas including salt purification, film characterization, modeling, and reactor 2 design / fabrication. However, the key project objective of the growth of a crystalline GaN film on the seed template was not achieved. Amorphous film growth on the order of a few tenths of a micron has been detected with a film composition including Ga and N, plus several other impurities originating from the process solution and hardware. The presence of these impurities, particularly the oxygen, has inhibited the demonstration of crystalline GaN film growth on the seed template. However, the

  11. Miniaturized preconcentration methods based on liquid-liquid extraction and their application in inorganic ultratrace analysis and speciation: A review

    International Nuclear Information System (INIS)

    Pena-Pereira, Francisco; Lavilla, Isela; Bendicho, Carlos

    2009-01-01

    Liquid-liquid extraction (LLE) is widely used as a pre-treatment technique for separation and preconcentration of both organic and inorganic analytes from aqueous samples. Nevertheless, it has several drawbacks, such as emulsion formation or the use of large volumes of solvents, which makes LLE expensive and labour intensive. Therefore, miniaturization of conventional liquid-liquid extraction is needed. The search for alternatives to the conventional LLE using negligible volumes of extractant and the minimum number of steps has driven the development of three new miniaturized methodologies, i.e. single-drop microextraction (SDME), hollow fibre liquid-phase microextraction (HF-LPME) and dispersive liquid-liquid microextraction (DLLME). The aim of this paper is to provide an overview of these novel preconcentration approaches and their potential use in analytical labs involved in inorganic (ultra)trace analysis and speciation. Relevant applications to the determination of metal ions, metalloids, organometals and non-metals are included

  12. Standard Test Method for Water Absorption, Bulk Density, Apparent Porosity, and Apparent Specific Gravity of Fired Whiteware Products

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2006-01-01

    1.1 This test method covers procedures for determining water absorption, bulk density, apparent porosity, and apparent specific gravity of fired unglazed whiteware products. 1.2 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  13. Major and trace elements in mouse bone measured by surface and bulk sensitive methods

    International Nuclear Information System (INIS)

    Benkoe, I.; Geresi, K.; Ungvari, E.; Szabo, B.; Paripas, B.

    2011-01-01

    Complete text of publication follows. In the past years an increasing research interest turned to the accurate determination of the components of bone samples. These investigations focused on both the major and trace elements in the bone. Work in this field is strongly motivated because various major and trace element concentrations can be good indicators of several diseases. Number of studies also focused on the determination of the components both in the organic and inorganic parts of the bone separately, because they both have role during bone remodeling processes. Also important to note that bone can be one of the final destinations in the body where toxic elements are deposited. In this work we performed various surface and bulk sensitive analyses for the mouse bone samples to determine its major and trace element components. We have shown concentration profiles for various major and observable trace elements of the mouse bone. We found, in accordance with our expectation, that the mostly surface sensitive XPS technique is not suitable to determine the concentration of the trace elements in bone samples. It was also shown that XPS is a valuable tool not only in the determination of the chemical states of the major components of the bone powder but in the quantitative determination of their relative concentrations. Both the major and the trace elements of the bone samples are determined using PIXE and SNMS spectra. Although the information depths are very different for PIXE (a few tens of micrometer) and for XPS analysis (a few nanometers), our present PIXE result, using the bone sample in its original form for the concentration ratio between Ca and P is in excellent agreement with the XPS results using calcinated mouse bone powder. Discrepancy in Ca/Mg ratio (PIXE: 35.7 and XPS: 12.7) maybe due to many factors, which influence this ratio in bone samples. In the case of PIXE we studied native bones and determined composition of the compact bone at outside

  14. Evaluation of alternative methods of simulating asymmetric bulk heating in fusion reactor blanket/shield components

    International Nuclear Information System (INIS)

    Deis, G.A.; Longhurst, G.R.; Miller, L.G.; Wadkins, R.P.; Wessol, D.E.

    1981-10-01

    As a part of Phase O, Test Program Element-II of the Office of Fusion Energy First Wall/Blanket/Shield Engineering Test Program, a study was conducted by EG and G Idaho, Inc., to identify, characterize, and recommend alternative approaches for simulating fusion bulk heating in blanket/shield components. This is the report on that effort. Since the usefulness of any simulation approach depends upon the particular experiment considered, classes of problem types (thermal-hydraulic, thermomechanical, etc.) and material types (structure, solid breeder, etc.) are developed. The evaluation of the various simulation approaches is performed for the various significant combinations of problem class and material class. The simulation approaches considered are discrete-source heating, direct resistance, electromagnetic induction, microwave heating, and nuclear heating. From the evaluations performed for each experiment type, discrete - source heating emerges as a good approach for bulk heating simulation in thermal - hydraulics experiments, and nuclear heating appears to be a good approach in experiments addressing thermomechanics and combined thermal-hydraulic/thermomechanics

  15. A new turn-on fluorimetric method for the rapid speciation of Cr(III)/Cr(VI) species in tea samples with rhodamine-based fluorescent reagent

    Science.gov (United States)

    Özyol, Esra; Saçmacı, Şerife; Saçmacı, Mustafa; Ülgen, Ahmet

    2018-02-01

    A new fluorimetric method with rhodamine-based fluorescent agent was developed for the rapid speciation of Cr(III)/Cr(VI) in tea, soil and water samples. The system, which utilizes a fluorescent reagent, was used for the first time after synthesis/characterization of 3‧,6‧-bis(diethylamino)-2-{[(1E)-(2,4-dimethoxyphenyl)methylene] amino}spiro[isoindole-1,9‧-xanthen]-3(2H)-one (BDAS). The reagent responds instantaneously at room temperature in a 1:1 stoichiometric manner to the amount of Cr(III). The selectivity of this system for Cr(III) over other metal ions is remarkably high, and its sensitivity is below 0.01 mg L- 1 in aqueous solutions which enables a simplification without any pretreatment of the real sample. The method has a wide linear range of 0.1-10 mg L- 1 and a detection limit of 0.15 μg L- 1 for Cr(III) while the relative standard deviation was 0.1% for 0.1 mg L- 1 Cr(III) concentration. The results of detection and recovery experiments for Cr(III) in tea, soil and water were satisfactory, indicating that the method has better feasibility and application potential in the routine determination and speciation of Cr(III)/Cr(VI). The results of analysis of the certified reference material (INCT-TL-1 tea sample and CWW-TM-D waste water) are in good agreement with the certified value.

  16. The heterogeneous response method applied to couple the average pin cell and bulk moderator in cluster geometry

    International Nuclear Information System (INIS)

    Lerner, A.M.

    1986-01-01

    The first step towards evaluation of the neutron flux throughout a fuel cluster usually consists of obtaining the multigroup flux distribution in the average pin cell and in the circular outside system of shroud and bulk moderator. Here, an application of the so-called heterogeneous response method (HRM) is described to find this multigroup flux. The rather complex geometry is reduced to a microsystem, the average pin cell, and the outside or macrosystem of shroud and bulk moderator. In each of these systems, collision probabilities are used to obtain their response fluxes caused by sources and in-currents. The two systems are then coupled by cosine currents across that fraction of the average pin-cell boundary, called 'window', that represents the average common boundary between pin cells and the outside system. (author)

  17. Comparison of various methods to determine bulk specific gravity of cores : an investigation of high values using AASHTO T275 - paraffin-coated method.

    Science.gov (United States)

    2012-07-01

    A report from a MoDOT asphalt paving project was that unexpected results were obtained when adhering to the standard for determination of bulk specific gravity of compacted asphalt mixture (Gmb) specimens, AASHTO T 166. The test method requires speci...

  18. Speciation of radionuclides in the environment

    International Nuclear Information System (INIS)

    Gunten, H.R. von; Benes, P.

    1994-02-01

    Methods for the determination of the speciation of radionuclides in aerosols, in aquatic solutions, in sediments, soils and rocks are reviewed. At present, most of the results about speciation are deduced from model calculations, model experiments, and separation of species (forms) of radionuclides, e.g., by sequential extraction procedures. Methods of direct determination of speciation of radionuclides (e.g. by laser induced spectroscopy) are in general not yet sensitive enough for a measurement of the very low concentrations of radionuclides in the environment. The methodological part of this paper is followed by a review of the very abundant literature about speciation of important radionuclides in the environment, i.e. in the atmosphere, hydrosphere and lithosphere. The review does not include the biosphere. Literature up to spring 1993 is included (with a few more recent additions). (author)

  19. Development and Validation of RP-HPLC Method for the Determination of Adefovir Dipivoxil in Bulk and in Pharmaceutical Formulation

    Directory of Open Access Journals (Sweden)

    Zaheer Ahmed

    2009-01-01

    Full Text Available A rapid and sensitive RP-HPLC method with UV detection (262 nm for routine analysis of adefovir dipivoxil in bulk and in pharmaceutical formulation was developed. Chromatography was performed with mobile phase containing a mixture of acetonitrile and phosphate buffer (50:50, v/v with flow rate 1.0 mL min-l. In the range of 5.0-100 µg/mL, the linearity of adefovir dipivoxil shows a correlation co-efficient of 0.9999. The proposed method was validated by determining sensitivity accuracy, precision, robustness stability, specificity, selectivity and system suitability parameters.

  20. Silicene-terminated surface of calcium and strontium disilicides: properties and comparison with bulk structures by computational methods

    Science.gov (United States)

    Brázda, Petr; Mutombo, Pingo; Ondráček, Martin; Corrêa, Cinthia Antunes; Kopeček, Jaromír; Palatinus, Lukáš

    2018-05-01

    The bulk and surface structures of calcium and strontium disilicides are investigated by computational methods using density functional theory. The investigated structures are R6, R3 and P1-CaSi2 and P1-SrSi2. The investigated properties are the cleavage energy at the silicene sheet, buckling of the bulk and surface silicene layers, charge transfer from calcium to silicon, band structure of bulk and surface-terminated structures and adsorption energies on H atoms and H2 molecules on the silicene-terminated surface of the R3 phase. The cleavage energy at the silicene surface is low in all cases. Structures P1-CaSi2 and R3-CaSi2 contain silicene sheets with different coordination to Ca, while R6-CaSi2 contains both types of the sheets. It is shown that the properties of the two types of silicene-like sheets in R6-CaSi2 are similar to those of the corresponding sheets in P1-CaSi2 and R3-CaSi2, and the thermodynamically stable R6 phase is a good candidate for experimental investigation of silicene-terminated surface in calcium disilicide.

  1. Development of a new, rapid and sensitive HPTLC method for estimation of Milnacipran in bulk, formulation and compatibility study

    Directory of Open Access Journals (Sweden)

    Gautam Singhvi

    2017-05-01

    Full Text Available A simple, sensitive and rapid high performance thin layer chromatographic (HPTLC method has been developed and validated for quantitative determination of Milnacipran Hydrochloride (MIL in bulk and formulations. The chromatographic development was carried out on HPTLC plates precoated with silica gel 60 F254 using a mixture of acetonitrile, water and ammonia (6:0.6:1.6 (v/v/v as mobile phase. Detection was carried out densitometrically at 220 nm. The Rf value of drug was found to be 0.63 ± 0.02. The method was validated as per ICH guideline with respect to linearity, accuracy, precision, robustness etc. The calibration curve was found to be linear over a range of 100–1000 ng μL−1 with a regression coefficient of 0.999. The accuracy was found to be very high (99.12–100.87%. %RSD values for intra-day and inter-day variation were not more than 1.43. The method has demonstrated high sensitivity and specificity. The method was applied for compatibility studies also. The method is new, simple and economic for routine estimation of MIL in bulk, preformulation studies and pharmaceutical formulation to help the industries as well as researchers for their sensitive determination of MIL rapidly at low cost in routine analysis.

  2. Radionuclide speciation in the environment: a review

    International Nuclear Information System (INIS)

    Moulin, V.; Moulin, C.

    2001-01-01

    Speciation determination is of prime importance to explain and evaluate the mobility, the toxicity and the risk resulting from the presence of trace elements in natural systems, in particular in the case of radionuclides, in the framework of environment and waste management purposes. The present paper will then focus more specifically on the physico-chemical speciation of radionuclides, and more particularly of actinides, in the environment, with emphasis on the behavior in solution: from a chemical point of view (with important ligands including colloidal phases) using experimental data and speciation calculations, as well as from a more technical point of view (with analytical methods for in situ speciation determination and thermodynamic data determination). A review of recent papers (mainly from CEA) is presented. (orig.)

  3. Stability indicating high performance thin layer chromatographic method for quantitation of venlafaxine in bulk and pharmaceutical dosage form

    Directory of Open Access Journals (Sweden)

    Sunil K Dubey

    2015-01-01

    Full Text Available Background: Venlafaxine (VEN is a phenethylamine bicyclic compound, chemically, 1-(2-[dimethyl amino]-1-[4-methoxy phenyl] ethyl cyclo-hexan-1ol hydrochloride. It is a antidepressant. It inhibits the reuptake of serotonin, nor adrenaline and dopamine to a lesser extent at the presynaptic membrane. Aim: A simple, rapid, precise, accurate, and economical high performance thin layer chromatographic (HPTLC method has been developed and validated for the determination of VEN both as a bulk drug and in formulation. Materials and Methods: The method uses aluminum plates precoated with silica gel 60 F254 as the stationary phase and dichloromethane:acetonitrile:N-hexane:triethylamine: 0.5:0.5:4:0.7 (v/v/v/v as mobile phase. Results: This system gave compact spots for VEN (R f = 0.46 ± 0.05. Forced degradation studies were done by subjecting VEN to acid and alkali hydrolysis, oxidation, and reduction. The peak of the degradation product was well resolved from that of the pure drug and had significant different R f values. Analysis of VEN was performed in the absorbance mode at 225 nm. The limit of detection and quantification were 12.48 and 37.81 ng/spot respectively. Conclusions: The developed method was validated and found to be simple, specific, accurate and precise and can be used for routine quality control analysis of VEN in bulk and pharmaceutical formulation.

  4. The determination of bulk (apparent) density of plant fibres by density method

    International Nuclear Information System (INIS)

    Sharifah Hanisah Syed Abd Aziz; Raja Jamal Raja hedar; Zahid Abdullah

    2004-01-01

    The absolute density of plant fibres excludes all pores and lumen and therefore is a measure of the solid matter of the fibres. On the other hand the bulk density, which is being discussed here, includes all the solid matter and the pores of the fibres. In this work, the apparent density of the fibre was measured by using the Archimedes principle, which involves the immersion of a known weight of fibre into a solvent of lower density than the fibre. Toluene with a density of about 860 kg/m3 was chosen as a solvent. A tuft of fibre was weighed and recorded as W fa . The fibre was then immersed in toluene, which wetted the fibre, and made to rest on the weighing pan submerged in the solvent and the weight of the immersed fibre was recorded as W fs . The apparent density was then calculated using the equation. All the measurements were taken at room temperature. The fibre samples were not oven dried prior to measurement. (Author)

  5. Development and Validation of UV Spectrophotometric Method For Determination of Bisoprolol Fumarate in Bulk and Pharmaceutical Dosage Forms

    Directory of Open Access Journals (Sweden)

    Shahinaz Mohammed

    2017-10-01

    Full Text Available In this study a simple, accurate and precise UV- spectrophotometric method was developed for the estimation of bisoprolol fumarate (BF in bulk and tablet dosage form. The method was based on measurement of absorbance of BF aqueous solution at 225 nm. Validation was conducted in accordance to ICH guidelines. The calibration curve was linear in the concentration range 5.0-30.0 µg/mL with correlation coefficient not less than 0.996. The limit of detection and limit of quantification were 0.22 μg/ml and 0.66 μg/ml, respectively. Intraday and intermediate precision of the developed method were reflected by the low RSD% values (1.19 and 0.854, respectively. The recovery percentage was 100.6 ± 0.6%, n=3. The proposed method was applied for the assay of BF in three different brands.

  6. Arsenic speciation results

    Data.gov (United States)

    U.S. Environmental Protection Agency — Linear combination fitting results of synchrotron data to determine arsenic speciation in soil samples. This dataset is associated with the following publication:...

  7. Chemical Speciation - General Information

    Science.gov (United States)

    This page includes general information about the Chemical Speciation Network that is not covered on the main page. Commonly visited documents, including calendars, site lists, and historical files for the program are listed here

  8. Searching for speciation genes

    DEFF Research Database (Denmark)

    Holt, Benjamin George; Côté, Isabelle M; Emerson, Brent C

    2011-01-01

    Closely related species that show clear phenotypic divergence, but without obvious geographic barriers, can provide opportunities to study how diversification can occur when opportunities for allopatric speciation are limited. We examined genetic divergence in the coral reef fish genus Hypoplectrus...

  9. A rapid alpha spectrometric method for estimation of 233U in bulk of thorium

    International Nuclear Information System (INIS)

    Rao, K.S.; Sankar, R.; Dhami, P.S.; Tripathi, S.C.; Gandhi, P.M.

    2015-01-01

    Analytical methods play important role in entire nuclear fuel cycle. Almost all the methods find applications in some way or the other in nuclear industry. Methods which cannot be directly used owing to selectivity, find application after chemical separation of analyte from interfering components. The analytical techniques used in PUREX process are almost well matured whereas in THOREX process the analytical techniques are constantly evolving as regards to simplicity, accuracy and time of analysis

  10. Method development for speciation analysis of nanoparticle and ionic forms of gold in biological samples by high performance liquid chromatography hyphenated to inductively coupled plasma mass spectrometry

    Science.gov (United States)

    Malejko, Julita; Świerżewska, Natalia; Bajguz, Andrzej; Godlewska-Żyłkiewicz, Beata

    2018-04-01

    A new method based on coupling high performance liquid chromatography (HPLC) to inductively coupled plasma mass spectrometry (ICP MS) has been developed for the speciation analysis of gold nanoparticles (AuNPs) and dissolved gold species (Au(III)) in biological samples. The column type, the composition and the flow rate of the mobile phase were carefully investigated in order to optimize the separation conditions. The usefulness of two polymeric reversed phase columns (PLRP-S with 100 nm and 400 nm pore size) to separate gold species were investigated for the first time. Under the optimal conditions (PLRP-S400 column, 10 mmol L-1 SDS and 5% methanol as the mobile phase, 0.5 mL min-1 flow rate), detection limits of 2.2 ng L-1 for Au(III), 2.8 ng L-1 for 10 nm AuNPs and 3.7 ng L-1 for 40 nm AuNPs were achieved. The accuracy of the method was proved by analysis of reference material RM 8011 (NIST) of gold nanoparticles of nominal diameter of 10 nm. The HPLC-ICP MS method has been successfully applied to the detection and size characterization of gold species in lysates of green algae Acutodesmus obliquus, typical representative of phytoplankton flora, incubated with 10 nm AuNPs or Au(III).

  11. Uranium speciation in plants

    International Nuclear Information System (INIS)

    Guenther, A.; Bernhard, G.; Geipel, G.; Reich, T.; Rossberg, A.; Nitsche, H.

    2003-01-01

    Detailed knowledge of the nature of uranium complexes formed after the uptake by plants is an essential prerequisite to describe the migration behavior of uranium in the environment. This study focuses on the determination of uranium speciation after uptake of uranium by lupine plants. For the first time, time-resolved laser-induced fluorescence spectroscopy and X-ray absorption spectroscopy were used to determine the chemical speciation of uranium in plants. Differences were detected between the uranium speciation in the initial solution (hydroponic solution and pore water of soil) and inside the lupine plants. The oxidation state of uranium did not change and remained hexavalent after it was taken up by the lupine plants. The chemical speciation of uranium was identical in the roots, shoot axis, and leaves and was independent of the uranium speciation in the uptake solution. The results indicate that the uranium is predominantly bound as uranyl(VI) phosphate to the phosphoryl groups. Dandelions and lamb's lettuce showed uranium speciation identical to lupine plants. (orig.)

  12. New spectrofluorimetric method for the determination of nizatidine in bulk form and in pharmaceutical preparations

    Science.gov (United States)

    Karasakal, Ayça; Ulu, Sevgi Tatar

    2013-08-01

    A simple, accurate and highly sensitive spectrofluorimetric method has been developed for determination of nizatidine in pure form and in pharmaceutical dosage forms. The method is based on the reaction between nizatidine and 1-dimethylaminonaphthalene-5-sulphonyl chloride in carbonate buffer, pH 10.5, to yield a highly fluorescent derivative peaking at 513 nm after excitation at 367 nm. Various factors affecting the fluorescence intensity of nizatidin-dansyl derivative were studied and conditions were optimized. The method was validated as per ICH guidelines. The fluorescence concentration plot was rectilinear over the range of 25-300 ng/mL. Limit of detection and limit of quantification were calculated as 11.71 and 35.73 ng/mL, respectively. The proposed method was successfully applied to pharmaceutical preparations.

  13. Development and Validation of HPLC Analytical Method for Chlorantraniliprole in Bulk and in the Formulation

    Directory of Open Access Journals (Sweden)

    Kapupara Pankaj P.

    2018-03-01

    Full Text Available Background: Chlorantraniliprole is widely used as a pesticide. It is only soluble in dimethyl formamide. However, most of the reported methods used acetonitrile and other solvents.

  14. A Newly Improved Modified Method Development and Validation of Bromofenac Sodium Sesquihydrate in Bulk Drug Manufacturing

    OpenAIRE

    Sunil Kumar Yelamanchi V; Useni Reddy Mallu; I. V Kasi Viswanath; D. Balasubramanyam; G. Narshima Murthy

    2016-01-01

    The main objective of this study was to develop a simple, efficient, specific, precise and accurate newly improved modified Reverse Phase High Performance Liquid Chromatographic Purity (or) Related substance method for bromofenac sodium sesquihydrate active pharmaceuticals ingredient dosage form. Validation of analytical method is the confirmation by examination and the provision of objective evidence that the particular requirements for a specific intended use are fulfilled as per ICH, USP...

  15. Uranium speciation in biofilms studies by laser fluorescence techniques

    International Nuclear Information System (INIS)

    Arnold, Thuro; Grossmann, Kay; Baumann, Nils

    2010-01-01

    Biofilms may immobilize toxic heavy metals in the environment and thereby influence their migration behaviour. The mechanisms of these processes are currently not understood, because the complexity of such biofilms creates many discrete geochemical microenvironments which may differ from the surrounding bulk solution in their bacterial diversity, their prevailing geochemical properties, e.g. pH and dissolved oxygen concentration, the presence of organic molecules, e.g. metabolites, and many more, all of which may affect metal speciation. To obtain such information, which is necessary for performance assessment studies or the development of new cost-effective strategies for cleaning waste waters, it is very important to develop new non-invasive methods applicable to study the interactions of metals within biofilm systems. Laser fluorescence techniques have some superior features, above all very high sensitivity for fluorescent heavy metals. An approach combining confocal laser scanning microscopy and laser-induced fluorescence spectroscopy for study of the interactions of biofilms with uranium is presented. It was found that coupling these techniques furnishes a promising tool for in-situ non-invasive study of fluorescent heavy metals within biofilm systems. Information on uranium speciation and uranium redox states can be obtained.

  16. Spectrophotometric method for quantitative determination of triclabendazole in bulk and pharmaceutical

    Directory of Open Access Journals (Sweden)

    Alankar Shrivastava

    2011-01-01

    Full Text Available Background: Triclabendazole (TCBZ, 6-chloro-5(2-3 dichlorophenoxy-2-methyl thio-benzimidazole, an halogenated benzimidazole (BZD thiol derivative, shows high efficacy against both the immature and mature stages of Fasciola hepatica in sheep and cattle, which is a differential feature compared to other available trematodicidal drugs. As a consequence of its excellent activity against the liver fluke, it has been extensively used and this has inevitably promoted the selection of TCBZ-resistant populations, which is now a worrying problem in several areas of the world. We propose simple ultraviolet spectrophotometric method for the estimation of triclabendazole in 0.1 methanolic HCl for the estimation of the drug. Method was validated as per ICH guidelines. Materials and Methods: Spectral absorbance measurements were made on Shimadzu UV-1800 with 10 mm matched quartz cells and dilutions were made in 0.1 M methanolic HCl. Results: The LOD and LOQ of triclabendazole at 305 nm were found to be 0.068434 and 2.73×10-4 μg/ml respectively. The calibration was linear in the range of 1-10 μg/ml. Analytical parameters such as stability, selectivity, accuracy, and precision have been established for the method in Endex and Fasinex tablets and evaluated statistically to assess the application of the method. Conclusion: Method passes all parameters with in desirable limits and found to be simple, stable, sensitive, reproducible, and accurate for the routine analysis of the drug in pharmaceutical formulations and in pharmaceutical investigations involving triclabendazole.

  17. Bulk-scaffolded hydrogen storage and releasing materials and methods for preparing and using same

    Science.gov (United States)

    Autrey, S Thomas [West Richland, WA; Karkamkar, Abhijeet J [Richland, WA; Gutowska, Anna [Richland, WA; Li, Liyu [Richland, WA; Li, Xiaohong S [Richland, WA; Shin, Yongsoon [Richland, WA

    2011-06-21

    Compositions are disclosed for storing and releasing hydrogen and methods for preparing and using same. These hydrogen storage and releasing materials exhibit fast release rates at low release temperatures without unwanted side reactions, thus preserving desired levels of purity and enabling applications in combustion and fuel cell applications.

  18. Simultaneous Estimation of Ibuprofen and Phenylephrine Hydrochloride in Bulk and Combined Dosage Form by First Derivative UV Spectrophotometry Method

    Directory of Open Access Journals (Sweden)

    Mehul Patel

    2013-01-01

    Full Text Available A simple, precise, rapid, and economic method was developed for the simultaneous determination of Ibuprofen and Phenylephrine HCl in bulk and combined dosage form. This method involves first-order derivative spectroscopy using 248 nm and 237 nm as zero crossing points for Ibuprofen and Phenylephrine HCl, respectively. For spectrophotometric method 0.1 N NaOH was used as a solvent. The linearity was established over the concentration range of 12–72 μg/mL and 1.5–22 μg/mL for Ibuprofen and Phenylephrine HCl with correlation coefficient (r2 of 0.9972 and 0.9981, respectively. The mean % recoveries were found to be in the range of 98.88% and 98.54% for Ibuprofen and Phenylephrine HCl, respectively. Interday and intraday studies showed repeatability of the method. The method was found to be specific and robust. The method was successfully applied to pharmaceutical formulation, with no interference from excipients as indicated by the recovery study. Results of analysis were validated statistically and by recovery studies.

  19. Structure and performance of polymer-derived bulk ceramics determined by method of filler incorporation

    Science.gov (United States)

    Konegger, T.; Schneider, P.; Bauer, V.; Amsüss, A.; Liersch, A.

    2013-12-01

    The effect of four distinct methods of incorporating fillers into a preceramic polymer matrix was investigated with respect to the structural and mechanical properties of the resulting materials. Investigations were conducted with a polysiloxane/Al2O3/ZrO2 model system used as a precursor for mullite/ZrO2 composites. A quantitative evaluation of the uniformity of filler distribution was obtained by employing a novel image analysis. While solvent-free mixing led to a heterogeneous distribution of constituents resulting in limited mechanical property values, a strong improvement of material homogeneity and properties was obtained by using solvent-assisted methods. The results demonstrate the importance of the processing route on final characteristics of polymer-derived ceramics.

  20. MATHEMATICAL OPTIMIZATION METHODS TO ESTABLISH ACTIVE PHASES ON HETEROGENEOUS CATALYSIS: CASE OF BULK TRANSITION METAL SULPHIDES

    Directory of Open Access Journals (Sweden)

    Iván Machín

    2015-03-01

    Full Text Available This paper presents a set of procedures based on mathematical optimization methods to establish optimal active sulphide phases with higher HDS activity. This paper proposes a list of active phases as a guide for orienting the experimental work in the search of new catalysts that permit optimize the HDS process. Studies in this paper establish Co-S, Cr-S, Nb-S and Ni-S systems have the greatest potential to improve HDS activity.

  1. Prevailing ship financing methods applied to major dry-bulk companies

    OpenAIRE

    Χριστοδούλου, Αγγελική

    2015-01-01

    Shipping finance of 2014 has altered substantially regarding that of last decades and the shipping companies’ traditional capital structure of bank lending along with shareholders equity gives way to sophisticated and innovative financing methods forming a new capital structure which is more complicated but serves better the present-day financial needs. Not only constitutes the scope of this dissertation to exhibit the current ship-financing instruments but also to seek the optimal capital st...

  2. Fabrication of ordered bulk heterojunction organic photovoltaic cells using nanopatterning and electrohydrodynamic spray deposition methods.

    Science.gov (United States)

    Park, Sung-Eun; Kim, Sehwan; Kim, Kangmin; Joe, Hang-Eun; Jung, Buyoung; Kim, Eunkyoung; Kim, Woochul; Min, Byung-Kwon; Hwang, Jungho

    2012-12-21

    Organic photovoltaic cells with an ordered heterojunction (OHJ) active layer are expected to show increased performance. In the study described here, OHJ cells were fabricated using a combination of nanoimprinting and electrohydrodynamic (EHD) spray deposition methods. After an electron donor material was nanoimprinted with a PDMS stamp (valley width: 230 nm, period: 590 nm) duplicated from a Si nanomold, an electron acceptor material was deposited onto the nanoimprinted donor layer using an EHD spray deposition method. The donor-acceptor interface layer was observed by obtaining cross-sectional images with a focused ion beam (FIB) microscope. The photocurrent generation performance of the OHJ cells was evaluated with the current density-voltage curve under air mass (AM) 1.5 conditions. It was found that the surface morphology of the electron acceptor layer affected the current and voltage outputs of the photovoltaic cells. When an electron acceptor layer with a smooth thin (250 nm above the valley of the electron donor layer) surface morphology was obtained, power conversion efficiency was as high as 0.55%. The electrohydrodynamic spray deposition method used to produce OHJ photovoltaic cells provides a means for the adoption of large area, high throughput processes.

  3. Speciation from photon to ion detection

    International Nuclear Information System (INIS)

    Moulin, C.

    2001-01-01

    New analytical techniques allowing to perform speciation in the framework of the nuclear fuel cycle are more and more needed. Among them, several laser-based analytical techniques present several advantages (non intrusive). Hence, Thermal Lensing (TL)/Photoacoustic (LIPAS), Time Resolved selective, sensitive Laser-Induced Fluorescence (TRLIF) have been used for actinides/lanthanides interaction and speciation studies in inorganic and organic matrices, Laser Ablation-Optical Emission Spectroscopy (LA-OES or LIBS) for direct studies on solids, liquids,... where in situ measurements (elemental or isotopic) are mandatory. In complementary to these photon-based methods, new ion detection methods such as ElectroSpray-Mass Spectrometry (ES-MS) seems promising for speciation studies. Principle, advantages and limitations as well as results obtained and trends for these different methods will be presented. (author)

  4. Mechanochemical Effects on the Synthesis of Copper Orthophosphate and cyclo-Tetraphosphate Bulks by the Hydrothermal Hot Pressing Method

    Directory of Open Access Journals (Sweden)

    Isao Tanaka

    2009-01-01

    Full Text Available Copper orthophosphate, Cu3(PO42, and cyclo-tetraphosphates, Cu2P4O12, were synthesized using phosphoric acid and basic copper carbonate, and then treated with a planetary mill for up to 360 minutes. The un-milled and milled samples were characterized by X-ray diffraction (XRD and Fourier transform infrared (FT-IR spectroscopy. SEM images, particle size distribution, specific surface area, UV-Vis reflectance spectra were also used to evaluate the materials. The un-milled and milled materials were used to fabricate copper phosphate bulks by a hydrothermal hot pressing method. The influence of powder condition on the sintering behavior of the copper phosphates was studied.

  5. Spectrophotometric method for estimation of amiloride in bulk and tablet dosage form

    Directory of Open Access Journals (Sweden)

    Aitha Vijaya Lakshmi

    2015-01-01

    Full Text Available Introduction: Amiloride chemically, 3,5-diamino-6-chloro-N-(diaminomethylene pyrazine-2-carboxamide. It is used in the management of congestive heart failure, available as Amifru tab, Amimide. It causes adverse effects like Nausea, diarrhea and dizziness. Materials: 0.1 N Hydrochloric acid, 0.1 N Sodium hydroxide and 1 mg/ml amiloride drug solution were required. Spectral and absorbance measurements were made using ELICO UV-160 double beam Spectrophotometer. Method: Amiloride drug solution concentration range of 25 to 125ug/ml in 0.1N HCl medium was scanned over the wave length range of 235-320 against blank prepared in 0.1N NaOH solution. Two wavelengths are selected one at positive peak 245 nm and another at negative peak 290 nm, the amplitude is calculated from these values. Results and Discussion: The sum of the absolute values at these wavelengths is called amplitude. The amplitude is proportional to the amount of drug. High accuracy, reproducibility and low t-values were reported from the calibration curve plotted with the amplitude verses amount of drug. So the proposed method is simple, less time consuming and it can be successfully adopted for the estimation of amiloride.

  6. Electrical properties of bulk InP synthesized by modified horizontal Bridgman method

    International Nuclear Information System (INIS)

    Pak, K.; Matsui, M.; Fukuhara, H.; Nishinaga, T.; Nakamura, T.; Yasuda, Y.

    1986-01-01

    High purity polycrystalline InP has been required for preparation of starting materials in LEC pulling. Usually, these materials are synthesized by the horizontal Bridgman (HB) or gradient freeze (GF) method. The major problem for InP synthesis has been attributed to silicon contamination during the growth, as shown by several workers. In a previous paper, the authors proposed a model in which the silicon contamination would occur due to the transport of SiO and In/sub 2/O gas species from the In-P melt to the phosphorus region by the reaction of the melt with the quartz boat in the HB growth system and suggested that the Si concentration in the In-P melt would have an intimate correlation with the temperature in the phosphorus region. However, the effect of the temperature in the phosphorus region on the electrical properties has not been studied in details as of yet. In this note, a modified horizontal Bridgman (MHB) method was developed to reduce the residual donor impurities, and the reduction mechanism is discussed

  7. Method of aeration disinfecting and drying grain in bulk and pretreating seeds and a transverse blow silo grain dryer therefor

    Science.gov (United States)

    Danchenko, Vitaliy G [Dnipropetrovsk, UA; Noyes, Ronald T [Stillwater, OK; Potapovych, Larysa P [Dnipropetrovsk, UA

    2012-02-28

    Aeration drying and disinfecting grain crops in bulk and pretreating seeds includes passing through a bulk of grain crops and seeds disinfecting and drying agents including an ozone and air mixture and surrounding air, subdividing the disinfecting and drying agents into a plurality of streams spaced from one another in a vertical direction, and passing the streams at different heights through levels located at corresponding heights of the bulk of grain crops and seeds transversely in a substantially horizontal direction.

  8. Development and Validation of UV-Visible Spectrophotometric Methods for Simultaneous Estimation of Thiocolchicoside and Dexketoprofen in Bulk and Tablet Dosage Form

    OpenAIRE

    M. T. Harde; S. B. Jadhav; D. L. Dharam; P. D. Chaudhari

    2012-01-01

    Development and validation of two simple, accurate, precise and economical UV Spectrophotometric methods for simultaneous estimation of Thiocolchicoside and Dexketoprofen in bulk and in tablet dosage form. The methods employed were Method-1 Absorbance correction method and Method-2 First order derivative spectroscopic method. In method-1 Absorbance is measured at two wavelengths 370nm at which Dexketoprofen has no absorbance and 255nm at which both the drug have considerable absorbance. In me...

  9. Changes in zinc speciation with mine tailings acidification in a semi-arid weathering environment

    Science.gov (United States)

    Hayes, Sarah M.; O’Day, Peggy A.; Webb, Sam M.; Maier, Raina M.; Chorover, Jon

    2011-01-01

    High concentrations of residual metal contaminants in mine tailings can be transported easily by wind and water, particularly when tailings remain unvegetated for decades following mining cessation, as is the case in semi-arid landscapes. Understanding the speciation and mobility of contaminant metal(loid)s, particularly in surficial tailings, is essential to controlling their phytotoxicities and to revegetating impacted sites. In prior work, we showed that surficial tailings samples from the Klondyke State Superfund Site (AZ, USA), ranging in pH from 5.4 to 2.6, represent a weathering series, with acidification resulting from sulfide mineral oxidation, long-term Fe hydrolysis, and a concurrent decrease in total (6,000 to 450 mg kg−1) and plant-available (590 to 75 mg kg−1) Zn due to leaching losses and changes in Zn speciation. Here, we used bulk and micro-focused Zn K-edge X-ray absorption spectroscopy (XAS) data and a six-step sequential extraction procedure to determine tailings solid phase Zn speciation. Bulk sample spectra were fit by linear combination using three references: Zn-rich phyllosilicate (Zn0.8talc), Zn sorbed to ferrihydrite (ZnadsFeOx), and zinc sulfate (ZnSO4·7H2O). Analyses indicate that Zn sorbed in tetrahedral coordination to poorly-crystalline Fe and Mn (oxyhydr)oxides decreases with acidification in the weathering sequence, whereas octahedral zinc in sulfate minerals and crystalline Fe oxides undergoes a relative accumulation. Micro-scale analyses identified hetaerolite (ZnMn2O4), hemimorphite (Zn4Si2O7(OH)2·H2O) and sphalerite (ZnS) as minor phases. Bulk and micro-focused spectroscopy complement the chemical extraction results and highlight the importance of using a multi-method approach to interrogate complex tailings systems. PMID:21761897

  10. CONCAWE effluent speciation project

    Energy Technology Data Exchange (ETDEWEB)

    Leonards, P.; Comber, M.; Forbes, S.; Whale, G.; Den Haan, K.

    2010-09-15

    In preparation for the implementation of the EU REACH regulation, a project was undertaken to transfer the high-resolution analytical method for determining hydrocarbon blocks in petroleum products by comprehensive two-dimensional gas chromatography (GCxGC) to a laboratory external to the petroleum industry (Institute for Environmental Studies (IVM) of the VU University of Amsterdam). The method was validated and used for the analysis of petroleum hydrocarbons extracted from refinery effluents. The report describes the technology transfer and the approaches used to demonstrate the successful transfer and application of the GCxGC methodology from analysing petroleum products to the quantitative determination of hydrocarbon blocks in refinery effluents. The report describes all the methods used for all the determinations on the effluent samples along with an overview of the results obtained which are presented in summary tables and graphs. These data have significantly improved CONCAWE's knowledge of what refineries emit in their effluents. A total of 111 Effluent Discharge Samples from 105 CONCAWE refineries in Europe were obtained in the period June 2008 to March 2009. These effluents were analysed for metals, standard effluent parameters (including COD, BOD), oil in water, BTEX and volatile organic compounds. The hydrocarbon speciation determinations and other hydrocarbon analyses are also reported. The individual refinery analytical results are included into this report, coded as per the CONCAWE system. These data will be, individually, communicated to companies and refineries. The report demonstrates that it is feasible to conduct a research programme to investigate the fate and effects of hydrocarbon blocks present in discharged refinery effluents.

  11. Development and validation of a simple spectrophotometric method for the determination of methyldopa in both bulk and marketed dosage formulations

    Directory of Open Access Journals (Sweden)

    Paulo Roberto da Silva Ribeiro

    2014-09-01

    Full Text Available A simple, precise, sensitive, rapid, specific and economical spectrophotometric method was developed to determine methyldopa (MTD content in bulk and pharmaceutical dosage formulations. The proposed method was based on the formation of a colored product from the nitrosation reaction of MTD with sodium nitrite in an acid medium. The resultant nitroso derivative species reacts further with sodium hydroxide and is converted it into a more stable compound. This yellow nitrosation product exhibited an absorption maximum at 430 nm. Beer's Law was obeyed in a concentration range of 6.37 to 82.81 μg mL-1 MTD with an excellent coefficient of determination (R2 = 0.9998. No interference was observed from common excipients in formulations. The results showed the method to be simple, accurate and readily applied for the determination of MTD in pure form and in pharmaceutical preparations. The analytical results obtained for these products using the proposed method are in agreement with those of the Brazilian Pharmacopoeia procedure at a 95% confidence level.

  12. SWeRF--A method for estimating the relevant fine particle fraction in bulk materials for classification and labelling purposes.

    Science.gov (United States)

    Pensis, Ingeborg; Luetzenkirchen, Frank; Friede, Bernd

    2014-05-01

    In accordance with the European regulation for classification, labelling and packaging of substances and mixtures (CLP) as well as the criteria as set out in the Globally Harmonized System (GHS), fine fraction of crystalline silica (CS) has been classified as a specific target organ toxicity, the specific organ in this case being the lung. Generic cut-off values for products containing a fine fraction of CS trigger the need for a method for the quantification of the fine fraction of CS in bulk materials. This article describes the so-called SWeRF method, the size-weighted relevant fine fraction. The SWeRF method combines the particle size distribution of a powder with probability factors from the EN 481 standard and allows the relevant fine fraction of a material to be calculated. The SWeRF method has been validated with a number of industrial minerals. This will enable manufacturers and blenders to apply the CLP and GHS criteria for the classification of mineral products containing RCS a fine fraction of CS.

  13. Equivalence of the equilibrium and the nonequilibrium molecular dynamics methods for thermal conductivity calculations: From bulk to nanowire silicon

    Science.gov (United States)

    Dong, Haikuan; Fan, Zheyong; Shi, Libin; Harju, Ari; Ala-Nissila, Tapio

    2018-03-01

    Molecular dynamics (MD) simulations play an important role in studying heat transport in complex materials. The lattice thermal conductivity can be computed either using the Green-Kubo formula in equilibrium MD (EMD) simulations or using Fourier's law in nonequilibrium MD (NEMD) simulations. These two methods have not been systematically compared for materials with different dimensions and inconsistencies between them have been occasionally reported in the literature. Here we give an in-depth comparison of them in terms of heat transport in three allotropes of Si: three-dimensional bulk silicon, two-dimensional silicene, and quasi-one-dimensional silicon nanowire. By multiplying the correlation time in the Green-Kubo formula with an appropriate effective group velocity, we can express the running thermal conductivity in the EMD method as a function of an effective length and directly compare it to the length-dependent thermal conductivity in the NEMD method. We find that the two methods quantitatively agree with each other for all the systems studied, firmly establishing their equivalence in computing thermal conductivity.

  14. A simple differential steady-state method to measure the thermal conductivity of solid bulk materials with high accuracy.

    Science.gov (United States)

    Kraemer, D; Chen, G

    2014-02-01

    Accurate measurements of thermal conductivity are of great importance for materials research and development. Steady-state methods determine thermal conductivity directly from the proportionality between heat flow and an applied temperature difference (Fourier Law). Although theoretically simple, in practice, achieving high accuracies with steady-state methods is challenging and requires rather complex experimental setups due to temperature sensor uncertainties and parasitic heat loss. We developed a simple differential steady-state method in which the sample is mounted between an electric heater and a temperature-controlled heat sink. Our method calibrates for parasitic heat losses from the electric heater during the measurement by maintaining a constant heater temperature close to the environmental temperature while varying the heat sink temperature. This enables a large signal-to-noise ratio which permits accurate measurements of samples with small thermal conductance values without an additional heater calibration measurement or sophisticated heater guards to eliminate parasitic heater losses. Additionally, the differential nature of the method largely eliminates the uncertainties of the temperature sensors, permitting measurements with small temperature differences, which is advantageous for samples with high thermal conductance values and/or with strongly temperature-dependent thermal conductivities. In order to accelerate measurements of more than one sample, the proposed method allows for measuring several samples consecutively at each temperature measurement point without adding significant error. We demonstrate the method by performing thermal conductivity measurements on commercial bulk thermoelectric Bi2Te3 samples in the temperature range of 30-150 °C with an error below 3%.

  15. RP-HPLC-DAD method for the determination of phenylepherine, paracetamol, caffeine and chlorpheniramine in bulk and marketed formulation

    Directory of Open Access Journals (Sweden)

    A.P. Dewani

    2014-11-01

    Full Text Available A simple, specific and accurate isocratic RP-HPLC-DAD method was developed for the simultaneous determination of phenylephrine, paracetamol, caffeine and chlorpheniramine in bulk and tablet dosage form. The four contents are present in variable concentrations and have variable chromatographic behavior making the process of analysis very difficult. For present studies a reversed-phase C-18 column (150 mm × 4.5 mm i.d., particle size 5 μm with mobile phase consisting of acetonitrile, methanol and 10 Mm phosphate buffer 16:22:62 (v/v (pH of buffer 2.5 ± 0.02, adjusted with ortho phosphoric acid was used. The flow rate was 1.0 ml/min and eluents were monitored at 280 nm. The mean retention times of phenylephrine, paracetamol, caffeine and chlorpheniramine were found to be 1.8, 3.1, 5.2 and 10.9 min, respectively. The method was validated in terms of linearity, range, specificity, accuracy, precision and robustness. The proposed method was successfully applied to the estimation of phenylephrine, paracetamol, caffeine and chlorpheniramine in combined tablet dosage form.

  16. Ultrafiltration technique in conjunction with competing ligand exchange method for Ni–humics speciation in aquatic environment

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Boissel, M.; Reuillon, A.; Babu, P.V.R.; Parthiban, G.

    The combination of ultrafiltration technique with competing ligand exchange method provides a better understanding of interactions between Ni and different molecular weight fractions of humic acid (HA) at varying pH in aquatic environment...

  17. Stability-Indicating RP-HPLC Method for Determination of Guanfacine Hydrochloride in Bulk Drugs and in Pharmaceutical Dosage Form

    Directory of Open Access Journals (Sweden)

    Vinod K. Ahirrao

    2011-04-01

    Full Text Available A novel stability-indicating RP-HPLC method was developed and validated for quantitative determination of guanfacine hydrochloride in bulk drug and in pharmaceutical dosage form. An isocratic, reversed phase HPLC method was developed to separate the drug from the degradation products, using Apollo, C18 (250mm x 4.6mm, 5µm column with mobile phase of 50mM Ammonium acetate (volatile buffer and acetonitrile (65:35, v/v. UV detection has been done at wavelength 220 nm. The guanfacine hydrochloride was subjected to the stress conditions of hydrolysis (acid, base, oxidation, photolysis and thermal degradation. The stressed samples were analyzed by the proposed method. The analyte peak shape was excellent. The described method shows excellent linearity over a range of 30 – 450 µg/mL. The correlation coefficient for guanfacine hydrochloride was 0.999. The limit of detection for Guanfacine hydrochloride is 0.011 µg/mL and the limit of quantification is 0.038 µg/mL respectively.Degradation was observed for guanfacine hydrochloride in base, thermal and in 30% H2O2 conditions. The drug was found to be stable in the other stress conditions attempted. The degradation products were well resolved from main peak. The percentage recovery of guanfacine hydrochloride was ranged from (99.2% to 100.5% in pharmaceutical dosage form. The developed method was validated with respect to the linearity, accuracy (recovery, precision, specificity and robustness. The forced degradation studies prove the stability indicating power of the method.

  18. Development and validation of a simple and robust method for arsenic speciation in human urine using HPLC/ICP-MS.

    Science.gov (United States)

    Sen, Indranil; Zou, Wei; Alvaran, Josephine; Nguyen, Linda; Gajek, Ryszard; She, Jianwen

    2015-01-01

    In order to better distinguish the different toxic inorganic and organic forms of arsenic (As) exposure in individuals, we have developed and validated a simple and robust analytical method for determining the following six As species in human urine: arsenous (III) acid (As-III), As (V) acid, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine (AsB), and arsenocholine. In this method, human urine is diluted using a pH 5.8 buffer, separation is performed using an anion exchange column with isocratic HPLC, and detection is achieved using inductively coupled plasma-MS. The method uses a single mobile phase consisting of low concentrations of both phosphate buffer (5 mM) and ammonium nitrate salt (5 mM) at pH 9.0; this minimizes the column equilibration time and overcomes challenges with separation between AsB and As-III. In addition, As-III oxidation is prevented by degassing the sample preparation buffer at pH 5.8, degassing the mobile phase online at pH 9.0, and by the use of low temperature (-70 °C) and flip-cap airtight tubes for long term storage of samples. The method was validated using externally provided reference samples. Results were in agreement with target values at varying concentrations and successfully passed external performance test criteria. Internal QC samples were prepared and repeatedly analyzed to assess the method's long-term precision, and further analyses were completed on anonymous donor urine to assess the quality of the method's baseline separation. Results from analyses of external reference samples agreed with target values at varying concentrations, and results from precision studies yielded absolute CV values of 3-14% and recovery from 82 to 115% for the six As species. Analysis of anonymous donor urine confirmed the well-resolved baseline separation capabilities of the method for real participant samples.

  19. A novel method for the quantification, characterisation and speciation of silver nanoparticles in earthworms exposed in soil

    NARCIS (Netherlands)

    Makama, S.I.; Peters, R.J.B.; Undas, A.K.; Brink, van den N.W.

    2015-01-01

    Currently, metal engineered nanoparticles (ENPs) in tissues are generally quantified based on total concentrations after acid digestion of samples. Electron microscopy has also been used for non-quantitative characterisation of NPs in situ, and can be enhanced with tissue-processing methods that can

  20. Development of off-line layer chromatographic and total reflection X-ray fluorescence spectrometric methods for arsenic speciation

    Energy Technology Data Exchange (ETDEWEB)

    Mihucz, Victor G. [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); Moricz, Agnes M. [L. Eoetvoes University, Department of Chemical Technology and Environmental Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Kroepfl, Krisztina [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Szikora, Szilvia [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary); Tatar, Eniko [Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary); L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary); Parra, Lue Meru Marco [Universidad Centro-occidental Lisandro Alvarado, Decanato de Agronomia, Departamento de Quimica y Suelos Unidad de Analisis Instrumental, Apartado Postal 4076, Cabudare 3023 (Venezuela); Zaray, Gyula [Joint Research Group of Environmental Chemistry of Hungarian Academy of Sciences and L. Eoetvoes University, P. O. Box 32, H-1518 Budapest (Hungary) and Hungarian Satellite Centre of Trace Elements Institute to UNESCO, P. O. Box 32, H-1518 Budapest (Hungary) and L. Eoetvoes University, Department of Inorganic and Analytical Chemistry, P.O. Box 32, H-1518 Budapest (Hungary)]. E-mail: zaray@ludens.elte.hu

    2006-11-15

    Rapid and low cost off-line thin layer chromatography-total reflection X-ray fluorescence spectrometry and overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods have been developed for separation of 25 ng of each As(III), As(V), monomethyl arsonic acid and dimethylarsinic acid applying a PEI cellulose stationary phase on plastic sheets and a mixture of acetone/acetic acid/water = 2:1:1 (v/v/v) as eluent system. The type of eluent systems, the amounts (25-1000 ng) of As species applied to PEI cellulose plates, injection volume, development distance, and flow rate (in case of overpressured thin layer chromatography) were taken into consideration for the development of the chromatographic separation. Moreover, a microdigestion method employing nitric acid for the As spots containing PEI cellulose scratched from the developed plates divided into segments was developed for the subsequent total reflection X-ray fluorescence spectrometry analysis. The method was applied for analysis of root extracts of cucumber plants grown in As(III) containing modified Hoagland nutrient solution. Both As(III) and As(V) were detected by applying the proposed thin layer chromatography/overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods.

  1. Development of off-line layer chromatographic and total reflection X-ray fluorescence spectrometric methods for arsenic speciation

    International Nuclear Information System (INIS)

    Mihucz, Victor G.; Moricz, Agnes M.; Kroepfl, Krisztina; Szikora, Szilvia; Tatar, Eniko; Parra, Lue Meru Marco; Zaray, Gyula

    2006-01-01

    Rapid and low cost off-line thin layer chromatography-total reflection X-ray fluorescence spectrometry and overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods have been developed for separation of 25 ng of each As(III), As(V), monomethyl arsonic acid and dimethylarsinic acid applying a PEI cellulose stationary phase on plastic sheets and a mixture of acetone/acetic acid/water = 2:1:1 (v/v/v) as eluent system. The type of eluent systems, the amounts (25-1000 ng) of As species applied to PEI cellulose plates, injection volume, development distance, and flow rate (in case of overpressured thin layer chromatography) were taken into consideration for the development of the chromatographic separation. Moreover, a microdigestion method employing nitric acid for the As spots containing PEI cellulose scratched from the developed plates divided into segments was developed for the subsequent total reflection X-ray fluorescence spectrometry analysis. The method was applied for analysis of root extracts of cucumber plants grown in As(III) containing modified Hoagland nutrient solution. Both As(III) and As(V) were detected by applying the proposed thin layer chromatography/overpressured thin layer chromatography-total reflection X-ray fluorescence spectrometry methods

  2. Rapid allopatric speciation in logperch darters (Percidae: Percina).

    Science.gov (United States)

    Near, Thomas J; Benard, Michael F

    2004-12-01

    Theory predicts that clades diversifying via sympatric speciation will exhibit high diversification rates. However, the expected rate of diversification in clades characterized by allopatric speciation is less clear. Previous studies have documented significantly higher speciation rates in freshwater fish clades diversifying via sympatric versus allopatric modes, leading to suggestions that the geographic pattern of speciation can be inferred solely from knowledge of the diversification rate. We tested this prediction using an example from darters, a clade of approximately 200 species of freshwater fishes endemic to eastern North America. A resolved phylogeny was generated using mitochondrial DNA gene sequences for logperches, a monophyletic group of darters composed of 10 recognized species. Divergence times among logperch species were estimated using a fossil calibrated molecular clock in centrarchid fishes, and diversification rates in logperches were estimated using several methods. Speciation events in logperches are recent, extending from 4.20 +/- 1.06 million years ago (mya) to 0.42 +/- 0.22 mya, with most speciation events occurring in the Pleistocene. Diversification rates are high in logperches, at some nodes exceeding rates reported for well-studied adaptive radiations such as Hawaiian silverswords. The geographic pattern of speciation in logperches was investigated by examining the relationship between degree of sympatry and the absolute age of the contrast, with the result that diversification in logperches appears allopatric. The very high diversification rate observed in the logperch phylogeny is more similar to freshwater fish clades thought to represent examples of sympatric speciation than to clades representing allopatric speciation. These results demonstrate that the geographic mode of speciation for a clade cannot be inferred from the diversification rate. The empirical observation of high diversification rates in logperches demonstrates that

  3. Sample preparation method for the speciation of polybrominated diphenyl ethers and their methoxylated and hydroxylated analogues in diverse environmental matrices.

    Science.gov (United States)

    Sun, Jianteng; Liu, Jiyan; Liu, Qian; Qu, Guangbo; Ruan, Ting; Jiang, Guibin

    2012-01-15

    A reliable analytical method was developed here for the simultaneous separation, identification and quantification of ten polybrominated diphenyl ethers (PBDEs), nine methoxylated PBDEs (MeO-PBDEs) and ten hydroxylated PBDEs (OH-PBDEs) in various environmental matrices, including water, soil, sediment, plant, mollusk and fish. PBDEs and MeO-PBDEs were measured by gas chromatography coupled with mass spectrometry (GC/MS) and liquid chromatography coupled with electrospray ionization (negative)-tandem quadrupole mass spectrometry (LC/ESI(-)-MS/MS) for the separation and determination of OH-PBDEs without prior derivatization. After preliminary sample cleaning using acid silica gel, water-impregnated silica column separation of PBDEs, MeO-PBDEs and OH-PBDEs was proved to be rapid, simple, and efficient. For phenolic analytes, the method detection limits (MDLs) were 3.2-11.6pg/L in water sample and 2.8-18.4pg/g dry weight in solid samples. For neutral compounds, MDLs were 48.8-150.3pg/L in water sample and 46.5-170.8pg/g dry weight in solid samples. The method was validated using six kinds of environmental samples spiked with all analytes at three concentration levels (0.3ng, 2ng and 5ng, respectively) for recovery (71-113%) and repeatability determination (4-12%RSD). Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Optimization and characterization of bulk hexagonal boron nitride single crystals grown by the nickel-chromium flux method

    Science.gov (United States)

    Hoffman, Tim

    Hexagonal boron nitride (hBN) is a wide bandgap III-V semiconductor that has seen new interest due to the development of other III-V LED devices and the advent of graphene and other 2-D materials. For device applications, high quality, low defect density materials are needed. Several applications for hBN crystals are being investigated, including as a neutron detector and interference-less infrared-absorbing material. Isotopically enriched crystals were utilized for enhanced propagation of phonon modes. These applications exploit the unique physical, electronic and nanophotonics applications for bulk hBN crystals. In this study, bulk hBN crystals were grown by the flux method using a molten Ni-Cr solvent at high temperatures (1500°C) and atmospheric pressures. The effects of growth parameters, source materials, and gas environment on the crystals size, morphology and purity were established and controlled, and the reliability of the process was greatly improved. Single-crystal domains exceeding 1mm in width and 200microm in thickness were produced and transferred to handle substrates for analysis. Grain size dependence with respect to dwell temperature, cooling rate and cooling temperature were analyzed and modeled using response surface morphology. Most significantly, crystal grain width was predicted to increase linearly with dwell temperature, with single-crystal domains exceeding 2mm in at 1700°C. Isotopically enriched 10B and 11B hBN crystal were produced using a Ni-Cr-B flux method, and their properties investigated. 10B concentration was evaluated using SIMS and correlated to the shift in the Raman peak of the E2g mode. Crystals with enrichment of 99% 10B and >99% 11B were achieved, with corresponding Raman shift peaks at 1392.0 cm-1 and 1356.6 cm-1, respectively. Peak FWHM also decreased as isotopic enrichment approached 100%, with widths as low as 3.5 cm-1 achieved, compared to 8.0 cm-1 for natural abundance samples. Defect selective etching was

  5. The development of chemical speciation analysis

    International Nuclear Information System (INIS)

    Martin, R.; Santana, J.L.; Lima, L.; De La Rosa, D.; Melchor, K.

    2003-01-01

    The knowledge of many metals species on the environmental, its bioaccumulation, quantification and its effect in human body has been studied by a wide researchers groups in the last two decades. The development of speciation analysis has an vertiginous advance close to the developing of novel analytical techniques. Separation and quantification at low level is a problem that's has been afford by a coupling of high resolution chromatographic techniques like HPLC and HRGC with a specific method of detection (ICP-MS or CV-AAS). This methodological approach make possible the success in chemical speciation nowadays

  6. Gas chromatographic sulphur speciation in heavy crude oil using a modified standard D5623 method and microfluidic Deans switching.

    Science.gov (United States)

    Heshka, Nicole E; Choy, Joanne M; Chen, Jinwen

    2017-12-29

    A modification to American Society for Testing and Materials (ASTM) method D5623 is proposed to enable successful and repeatable analysis of heavy crude oil samples. A two-dimensional gas chromatography configuration was implemented, with separation of sulphur compounds occurring on two columns. A Deans switch is used to enable heart-cutting of volatile sulphur compounds onto a DB-Sulfur stationary phase, and separation occurs concurrently with the backflushing of the primary column. The use of a sulphur-selective detector increases selectivity, and 22 volatile sulphur species are quantified in less than 15min, which is almost half the time of the original ASTM method. Samples ranging from light distillation cuts to whole crudes (boiling from 100°C to >750°C) were analyzed with minimal sample preparation. The calculated limit of detection was 0.7mg/kg, repeatability was 3% relative standard deviation (RSD), and a linear range of 1-250mg/kg was obtained, with an R 2 value of 0.994 or better, depending on the compound. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  7. Optimization of cloud point extraction and solid phase extraction methods for speciation of arsenic in natural water using multivariate technique.

    Science.gov (United States)

    Baig, Jameel A; Kazi, Tasneem G; Shah, Abdul Q; Arain, Mohammad B; Afridi, Hassan I; Kandhro, Ghulam A; Khan, Sumaira

    2009-09-28

    The simple and rapid pre-concentration techniques viz. cloud point extraction (CPE) and solid phase extraction (SPE) were applied for the determination of As(3+) and total inorganic arsenic (iAs) in surface and ground water samples. The As(3+) was formed complex with ammonium pyrrolidinedithiocarbamate (APDC) and extracted by surfactant-rich phases in the non-ionic surfactant Triton X-114, after centrifugation the surfactant-rich phase was diluted with 0.1 mol L(-1) HNO(3) in methanol. While total iAs in water samples was adsorbed on titanium dioxide (TiO(2)); after centrifugation, the solid phase was prepared to be slurry for determination. The extracted As species were determined by electrothermal atomic absorption spectrometry. The multivariate strategy was applied to estimate the optimum values of experimental factors for the recovery of As(3+) and total iAs by CPE and SPE. The standard addition method was used to validate the optimized methods. The obtained result showed sufficient recoveries for As(3+) and iAs (>98.0%). The concentration factor in both cases was found to be 40.

  8. Systems and Methods for Implementing Bulk Metallic Glass-Based Strain Wave Gears and Strain Wave Gear Components

    Science.gov (United States)

    Hofmann, Douglas C. (Inventor); Wilcox, Brian (Inventor)

    2016-01-01

    Bulk metallic glass-based strain wave gears and strain wave gear components. In one embodiment, a strain wave gear includes: a wave generator; a flexspline that itself includes a first set of gear teeth; and a circular spline that itself includes a second set of gear teeth; where at least one of the wave generator, the flexspline, and the circular spline, includes a bulk metallic glass-based material.

  9. ARSENIC SPECIATION ANALYSIS IN HUMAN SALIVA

    Science.gov (United States)

    Background: Determination of arsenic species in human saliva is potentially useful for biomonitoring of human exposure to arsenic and for studying arsenic metabolism. However, there is no report on the speciation analysis of arsenic in saliva. Methods: Arsenic species in saliva ...

  10. Method to reduce levitation force decay of the bulk HTSC above the NdFeB guideway due to lateral movement

    Energy Technology Data Exchange (ETDEWEB)

    Ma, G T; Lin, Q X; Wang, J S; Wang, S Y; Deng, Z G; Lu, Y Y; Liu, M X; Zheng, J [Applied Superconductivity Lab, Mail Stop 152 Southwestern Jiaotong University, Chengdu, Sichuan 610031 (China)], E-mail: asclab@asclab.cn

    2008-06-15

    A magnetic levitation vehicle using bulk high-T{sub c} superconductors (HTSC) is considered as a promising transportation type thanks to its lateral inherent stability, but previous studies have found that the levitation force (LF) decays due to lateral movement. In this paper, a pre-load method is presented to reduce the LF decay, and the experimental results indicate that this method is very applicable in supressing this decay in spite of the applied field and material property of the bulk HTSC, and this effect can be ascribed to the reduction of the hysteresis loss in the bulk HTSC, i.e. more trapped magnetic flux after the pre-load case. In the end, experimental results indicate that the Halbach PMG has an advantage to reduce the cost of the PMG, but its rate of LF decay is also larger due to lateral movement.

  11. Study on the influence of X-ray tube spectral distribution on the analysis of bulk samples and thin films: Fundamental parameters method and theoretical coefficient algorithms

    International Nuclear Information System (INIS)

    Sitko, Rafal

    2008-01-01

    Knowledge of X-ray tube spectral distribution is necessary in theoretical methods of matrix correction, i.e. in both fundamental parameter (FP) methods and theoretical influence coefficient algorithms. Thus, the influence of X-ray tube distribution on the accuracy of the analysis of thin films and bulk samples is presented. The calculations are performed using experimental X-ray tube spectra taken from the literature and theoretical X-ray tube spectra evaluated by three different algorithms proposed by Pella et al. (X-Ray Spectrom. 14 (1985) 125-135), Ebel (X-Ray Spectrom. 28 (1999) 255-266), and Finkelshtein and Pavlova (X-Ray Spectrom. 28 (1999) 27-32). In this study, Fe-Cr-Ni system is selected as an example and the calculations are performed for X-ray tubes commonly applied in X-ray fluorescence analysis (XRF), i.e., Cr, Mo, Rh and W. The influence of X-ray tube spectra on FP analysis is evaluated when quantification is performed using various types of calibration samples. FP analysis of bulk samples is performed using pure-element bulk standards and multielement bulk standards similar to the analyzed material, whereas for FP analysis of thin films, the bulk and thin pure-element standards are used. For the evaluation of the influence of X-ray tube spectra on XRF analysis performed by theoretical influence coefficient methods, two algorithms for bulk samples are selected, i.e. Claisse-Quintin (Can. Spectrosc. 12 (1967) 129-134) and COLA algorithms (G.R. Lachance, Paper Presented at the International Conference on Industrial Inorganic Elemental Analysis, Metz, France, June 3, 1981) and two algorithms (constant and linear coefficients) for thin films recently proposed by Sitko (X-Ray Spectrom. 37 (2008) 265-272)

  12. Method optimization and quality assurance in speciation analysis using high performance liquid chromatography with detection by inductively coupled plasma mass spectrometry

    DEFF Research Database (Denmark)

    Larsen, Erik Huusfeldt

    1998-01-01

    Achievement of optimum selectivity, sensitivity and robustness in speciation analysis using high performance liquid chromatography (HPLC) with inductively coupled mass spectrometry (ICP-MS) detection requires that each instrumental component is selected and optimized with a view to the ideal....... The optimized anion and cation exchange HPLC-ICP-MS systems were used for arsenic speciation in contaminated ground water and in an in-house shrimp reference sample. For the purpose of verification, HPLC coupled with tandem mass spectrometry with electrospray ionization was additionally used for arsenic...... a mass balance of the analytes in each fraction of the extraction procedure, by recovery of spikes and by employing and comparing independent techniques. The urgent need for reference materials certified for elemental species is stressed....

  13. A simple method using on-line continuous leaching and ion exchange chromatography coupled to inductively coupled plasma mass spectrometry for the speciation analysis of bio-accessible arsenic in rice.

    Science.gov (United States)

    Horner, Nolan S; Beauchemin, Diane

    2012-03-02

    A simple method for the speciation analysis of bio-accessible arsenic (As) in rice was developed using a continuous on-line leaching method to release the bio-accessible fraction. The continuous on-line leaching method has several advantages over commonly used batch methods including quicker and easier sample preparation, reduced risk of contamination and access to real time leaching data. The bio-accessibility of As in the samples was monitored using inductively coupled plasma mass spectrometry (ICP-MS). Results from a certified reference material as well as cooked and uncooked white rice showed that the majority of As was leached by saliva. Results obtained using the continuous on-line leaching method were comparable to those obtained using a batch method. Speciation analysis of the saliva leachate was performed using ion exchange chromatography coupled to ICP-MS. The four most toxic forms of As (As(III), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA) and As(V)) were clearly separated within 5 min in a single chromatographic run. Over 92% of bio-accessible As in the certified reference material and uncooked white rice sample was in the form of DMA and As(V), whereas it was present as DMA and As(III) in the cooked white rice. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Simultaneous measurement of thermal conductivity and heat capacity of bulk and thin film materials using frequency-dependent transient thermoreflectance method.

    Science.gov (United States)

    Liu, Jun; Zhu, Jie; Tian, Miao; Gu, Xiaokun; Schmidt, Aaron; Yang, Ronggui

    2013-03-01

    The increasing interest in the extraordinary thermal properties of nanostructures has led to the development of various measurement techniques. Transient thermoreflectance method has emerged as a reliable measurement technique for thermal conductivity of thin films. In this method, the determination of thermal conductivity usually relies much on the accuracy of heat capacity input. For new nanoscale materials with unknown or less-understood thermal properties, it is either questionable to assume bulk heat capacity for nanostructures or difficult to obtain the bulk form of those materials for a conventional heat capacity measurement. In this paper, we describe a technique for simultaneous measurement of thermal conductivity κ and volumetric heat capacity C of both bulk and thin film materials using frequency-dependent time-domain thermoreflectance (TDTR) signals. The heat transfer model is analyzed first to find how different combinations of κ and C determine the frequency-dependent TDTR signals. Simultaneous measurement of thermal conductivity and volumetric heat capacity is then demonstrated with bulk Si and thin film SiO2 samples using frequency-dependent TDTR measurement. This method is further testified by measuring both thermal conductivity and volumetric heat capacity of novel hybrid organic-inorganic thin films fabricated using the atomic∕molecular layer deposition. Simultaneous measurement of thermal conductivity and heat capacity can significantly shorten the development∕discovery cycle of novel materials.

  15. Arsenic Speciation in Groundwater: Role of Thioanions

    Science.gov (United States)

    The behavior of arsenic in groundwater environments is fundamentally linked to its speciation. Understanding arsenic speciation is important because chemical speciation impacts reactivity, bioavailability, toxicity, and transport and fate processes. In aerobic environments arsen...

  16. Speciated Elemental and Isotopic Characterization of Atmospheric Aerosols - Recent Advances

    Science.gov (United States)

    Shafer, M.; Majestic, B.; Schauer, J.

    2007-12-01

    /labile components of PM, while simultaneously providing critical oxidation state speciation data. Importantly, the LWG- LPS can be deployed in a semi-real-time configuration to probe fine temporal scale variations in atmospheric processing or sources of PM. The sXAS is providing complementary oxidation state speciation of bulk PM. Using examples from our research; we will illustrate the capabilities and applications of these new methods.

  17. Bulk-Fill Resin Composites

    DEFF Research Database (Denmark)

    Benetti, Ana Raquel; Havndrup-Pedersen, Cæcilie; Honoré, Daniel

    2015-01-01

    the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization...... for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low......-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk...

  18. Redox speciation of final repository relevant elements using separation methods in combination with ICP mass spectrometry; Redoxspeziation von endlagerrelevanten Elementen mit Hilfe von Trennmethoden gekoppelt an ein Massenspektrometer mit induktiv gekoppeltem Plasma

    Energy Technology Data Exchange (ETDEWEB)

    Graser, Carl-Heinrich

    2015-12-18

    The long-term safety assessment for nuclear waste repositories requires a detailed understanding of the chemistry of actinide elements in the geosphere. The development of advanced analytical tools is required to gain detailed insights into actinide redox speciation in a given system. The mobility of radionuclides is mostly determined by the geochemical conditions which control the redox state of radionuclides. Besides the longlived radionuclides plutonium (Pu) and neptunium (Np), which are key elements in high level nuclear waste, iron (Fe) represents a main component in natural systems controlling redox related geochemical processes. Analytical techniques for determining oxidation state distribution for redox sensitive radionuclides and other metal ions often have a lack of sensitivity. The detection limits of these methods (i.e. UV/vis, TRLFS, XANES) are in general in the range of ≥ 10{sup -6} mol.L{sup -1}. As a consequence ultrasensitive new analytical techniques are required. Capillary electrophoresis (CE) and ion chromatography (IC) are powerful separation methods for metal ions. In the course of this thesis different speciation method for iron, neptunium and plutonium were optimized. With the optimized setup redox speciation analysis of these elements in different samples were done. Furthermore CE hyphenated to inductively coupled plasma sector field mass spectrometry (CE - ICP - SF - MS) was used to measure the redox speciation of Pu (III, IV, V, VI), Np (IV, V, VI) and Fe (II, III) at concentrations lower than 10{sup -7} mol.L{sup -1}. CE coupling and separation parameters such as sample gas pressure, make up flow rate, capillary position, auxiliary gas flow, as well as the electrolyte system were optimized to obtain the maximum sensitivity. The methodes detection limits are 10{sup -12} mol.L{sup -1} for Np and Pu. The various oxidation state species of Pu and Np in different samples were separated by application of an acetate based electrolyte system

  19. Method of altering the effective bulk density of solid material and the resulting product: hollow polymeric particles

    International Nuclear Information System (INIS)

    Kool, L.B.; Nolen, R.L.; Solomon, D.E.

    1981-01-01

    Hollow spherical particles are made by spraying a mixture of powdered solid material with a solution of a film-forming polymer in a solvent therefor into a heated chamber where the solvent evaporates. The powder is thereby captured in the wall of the hollow polymer particles formed. Such particles are used to form a suspension in a fluid material. The hollow particles are of such size and wall thickness, in relation to the bulk density of the powdered solid material, that the bulk density of each hollow spherical particle is commensurate with the density of the fluid material. The particles thereby remain in suspension over a substantial period of time with little or no agitation of the fluid. (author)

  20. Speciation of long-lived radionuclides in the environment

    Energy Technology Data Exchange (ETDEWEB)

    Xiaolin Hou

    2008-11-15

    This project started in November 2005 and ended in November 2008, the work and research approaches are summarized in this report. This project studied the speciation of radionuclides in environment. A number of speciation analytical methods are developed for determination of species of 129I, 99Tc, isotopes of Pu, and 237Np in seawater, fresh water, soil, sediment, vegetations, and concrete. The developed methods are used for the investigation of the chemical speciation of these radionuclides as well as their environmental behaviours, especially in Danish environment. In addition the speciation of Pu isotopes in waste samples from the decommissioning of Danish nuclear facilities is also investigated. The report summarizes these works completed in this project. Through this research project, a number of research papers have been published in the scientific journals, the research results has also been presented in the Nordic and international conference/meeting and communicated to international colleagues. Some publications are also enclosed to this report. (au)

  1. Chemical speciation of long-lived radionuclides in the environment

    International Nuclear Information System (INIS)

    Xiaolin Hou

    2008-11-01

    This project started in November 2005 and ended in November 2008, the work and research approaches are summarized in this report. This project studied the speciation of radionuclides in environment. A number of speciation analytical methods are developed for determination of species of 129 I, 99 Tc, isotopes of Pu, and 237 Np in seawater, fresh water, soil, sediment, vegetations, and concrete. The developed methods are used for the investigation of the chemical speciation of these radionuclides as well as their environmental behaviours, especially in Danish environment. In addition the speciation of Pu isotopes in waste samples from the decommissioning of Danish nuclear facilities is also investigated. The report summarizes these works completed in this project. Through this research project, a number of research papers have been published in the scientific journals, the research results has also been presented in the Nordic and international conference/meeting and communicated to international colleagues. Some publications are also enclosed to this report. (au)

  2. Hitchhiking to speciation.

    Directory of Open Access Journals (Sweden)

    Daven C Presgraves

    Full Text Available The modern evolutionary synthesis codified the idea that species exist as distinct entities because intrinsic reproductive barriers prevent them from merging together. Understanding the origin of species therefore requires understanding the evolution and genetics of reproductive barriers between species. In most cases, speciation is an accident that happens as different populations adapt to different environments and, incidentally, come to differ in ways that render them reproductively incompatible. As with other reproductive barriers, the evolution and genetics of interspecific hybrid sterility and lethality were once also thought to evolve as pleiotripic side effects of adaptation. Recent work on the molecular genetics of speciation has raised an altogether different possibility-the genes that cause hybrid sterility and lethality often come to differ between species not because of adaptation to the external ecological environment but because of internal evolutionary arms races between selfish genetic elements and the genes of the host genome. Arguably one of the best examples supporting a role of ecological adaptation comes from a population of yellow monkey flowers, Mimulus guttatus, in Copperopolis, California, which recently evolved tolerance to soil contaminants from copper mines and simultaneously, as an incidental by-product, hybrid lethality in crosses with some off-mine populations. However, in new work, Wright and colleagues show that hybrid lethality is not a pleiotropic consequence of copper tolerance. Rather, the genetic factor causing hybrid lethality is tightly linked to copper tolerance and spread to fixation in Copperopolis by genetic hitchhiking.

  3. Speciation analysis of radionuclides

    International Nuclear Information System (INIS)

    Salbu, B.

    2010-01-01

    Full text: Naturally occurring and artificially produced radionuclides in the environment can be present in different physico-chemical forms (i. e. radionuclide species) varying in size (nominal molecular mass), charge properties and valence, oxidation state, structure and morphology, density, complexing ability etc. Low molecular mass (LMM) species are believed to be mobile and potentially bioavailable, while high molecular mass (HMM) species such as colloids, polymers, pseudocolloids and particles are considered inert. Due to time dependent transformation processes such as mobilization of radionuclide species from solid phases or interactions of mobile and reactive radionuclide species with components in soils and sediments, however, the original distribution of radionuclides deposited in ecosystems will change over time and influence the ecosystem behaviour. To assess the environmental impact from radionuclide contamination, information on radionuclide species deposited, interactions within affected ecosystems and the time-dependent distribution of radionuclide species influencing mobility and biological uptake is essential. The development of speciation techniques to characterize radionuclide species in waters, soils and sediments should therefore be essential for improving the prediction power of impact and risk assessment models. The present paper reviews fractionation techniques which should be utilised for radionuclide speciation purposes. (author)

  4. Developing bulk exchange spring magnets

    Science.gov (United States)

    Mccall, Scott K.; Kuntz, Joshua D.

    2017-06-27

    A method of making a bulk exchange spring magnet by providing a magnetically soft material, providing a hard magnetic material, and producing a composite of said magnetically soft material and said hard magnetic material to make the bulk exchange spring magnet. The step of producing a composite of magnetically soft material and hard magnetic material is accomplished by electrophoretic deposition of the magnetically soft material and the hard magnetic material to make the bulk exchange spring magnet.

  5. Preparation by Poly(Acrylic Acid) Sol-Gel Method and Thermoelectric Properties of γ-Na x CoO2 Bulk Materials

    Science.gov (United States)

    Li, Xiaoyu; Zhang, Li; Tang, Xinfeng

    2017-11-01

    γ-Na x CoO2 single-phase powders have been synthesized by a poly(acrylic acid) (PAA) sol-gel (SG) method, and γ-Na x CoO2 bulk ceramic fabricated using spark plasma sintering. The effects of the PAA concentration on the sample phase composition and morphology were investigated. The thermoelectric properties of the γ-Na x CoO2 bulk ceramic were also studied. The results show that the PAA concentration did not significantly affect the crystalline phase of the product. However, agglomeration of γ-Na x CoO2 crystals was suppressed by the steric effect of PAA. The Na x CoO2 bulk ceramic obtained using the PAA SG method had higher crystallographic anisotropy, better chemical homogeneity, and higher density than the sample obtained by solid-state reaction (SSR), leading to improved thermoelectric performance. The PAA SG sample had power factor (in-plane PF = σS 2) of 0.61 mW m-1 K-2 and dimensionless figure of merit ( ZT) along the in-plane direction of 0.19 at 900 K, higher than for the SSR sample (in-plane PF = 0.51 mW m-1 K-2, in-plane ZT = 0.17). These results demonstrate that a simple and feasible PAA SG method can be used for synthesis of Na x CoO2 ceramics with improved thermoelectric properties.

  6. Trace element speciation in the environment

    International Nuclear Information System (INIS)

    Heumann, Klaus G.

    2001-01-01

    The production of methylated heavy metal species in the ocean was reviewed and shown to be correlated with biological parameters demonstrating them to be of biogenic origin. Methods for the determination of the species were discussed. The potential for the use of isotopic spiking either in 'species specific' or 'non-species specific' formats was identified as a valuable tool in the struggle for accuracy, specificity and precision in speciation analysis. The value of using a size exclusion chromatographic method in conjunction with non-species specific spiking IDMS was highlighted with an example illustrating the molecular mass fractions associated with halogenated species from a humic sample. Additional recommendations that the Agency might wish to consider when evaluating its potential role as a service to Member States engaged in speciation activities are also given

  7. Development and Validation of a Stability-Indicating RP-HPLC Method for Rapid Determination of Doxycycline in Pharmaceutical Bulk and Dosage Forms

    OpenAIRE

    Shabnam Pourmoslemi, Soroush Mirfakhraee, Saeid Yaripour, Ali Mohammadi

    2016-01-01

    Background: A rapid stability-indicating RP-HPLC method for analysis of doxycycline in the presence of its degradation products was developed and validated. Methods: Forced degradation studies were carried out on bulk samples and capsule dosage forms of doxycycline using acid, base, H2O2, heat, and UV light as described by ICH for stress conditions to demonstrate the stability-indicating power of the method. Separations were performed on a Perfectsil® Target ODS column (3-5µm, 125 mm×4 mm), u...

  8. Speciation of arsenic and mercury in feed: why and how?

    DEFF Research Database (Denmark)

    Hedegaard, Rikke Susanne Vingborg; Sloth, Jens Jørgen

    2011-01-01

    The understanding of the mechanisms of biological activities and biotransformation of trace elements such as arsenic and mercury has improved during recent years with the help of chemical speciation studies. However, the most important practical application of elemental speciation is in the area ...... in feed as well as initiatives for the establishment of standardized methods for determination of inorganic arsenic and methylmercury are presented.......The understanding of the mechanisms of biological activities and biotransformation of trace elements such as arsenic and mercury has improved during recent years with the help of chemical speciation studies. However, the most important practical application of elemental speciation is in the area...... of toxicology. Toxicological knowledge on the individual trace element species can lead to more specific legislation of hazardous substances found in feed. Examples here are arsenic, where the inorganic forms are the most toxic, and mercury, where the organic form methylmercury is more toxic than inorganic...

  9. Speciation and internal dosimetry: from chemical species to dosimetric models

    International Nuclear Information System (INIS)

    Paquet, F.; Frelon, S.; Cote, G.; Madic, C.

    2004-01-01

    Speciation studies refer to the distribution of species in a particular sample or matrix. These studies are necessary to improve the description, understanding and prediction of trace element kinetics and toxicity. In case of internal contamination with radionuclides, speciation studies could help to improve both the biokinetic and dosimetric models for radionuclides. There are different methods to approach the speciation of radionuclide in a biological system, depending on the degree of accuracy needed and the level of uncertainties accepted. Among them, computer modelling and experimental determination are complementary approaches. This paper describes what is known about speciation of actinides in blood, GI-tract, liver and skeleton and of their consequences in terms of internal dosimetry. The conclusion is that such studies provide very valuable data and should be targeted in the future on some specific tissues and biomolecules. (authors)

  10. The contribution of chemical speciation to internal dosimetry

    International Nuclear Information System (INIS)

    Paquet, F.; Frelon, S.; Cote, G.; Madic, C.

    2003-01-01

    Speciation studies refer to the distribution of species in a particular sample or matrix. These studies are necessary to improve the description, understanding and prediction of trace element kinetics and toxicity. In the case of internal contamination with radionuclides, speciation studies could help to improve both the biokinetic and dosimetric models for radionuclides. There are different methods to approach the speciation of radionuclides in a biological system, depending on the degree of accuracy needed and the level of uncertainties accepted. Among them, computer modelling and experimental determination are complementary approaches. This paper describes what is known about speciation of actinides in blood, GI tract, liver and skeleton and of their consequences in terms of internal dosimetry. The conclusion is that such studies provide very valuable data and should be targeted in the future on some specific tissues and biomolecules. (author)

  11. Self-consistent approach for neutral community models with speciation

    Science.gov (United States)

    Haegeman, Bart; Etienne, Rampal S.

    2010-03-01

    Hubbell’s neutral model provides a rich theoretical framework to study ecological communities. By incorporating both ecological and evolutionary time scales, it allows us to investigate how communities are shaped by speciation processes. The speciation model in the basic neutral model is particularly simple, describing speciation as a point-mutation event in a birth of a single individual. The stationary species abundance distribution of the basic model, which can be solved exactly, fits empirical data of distributions of species’ abundances surprisingly well. More realistic speciation models have been proposed such as the random-fission model in which new species appear by splitting up existing species. However, no analytical solution is available for these models, impeding quantitative comparison with data. Here, we present a self-consistent approximation method for neutral community models with various speciation modes, including random fission. We derive explicit formulas for the stationary species abundance distribution, which agree very well with simulations. We expect that our approximation method will be useful to study other speciation processes in neutral community models as well.

  12. Effect of cooking method on the fatty acid content of reduced-fat and PUFA-enriched pork patties formulated with a konjac-based oil bulking system.

    Science.gov (United States)

    Salcedo-Sandoval, Lorena; Cofrades, Susana; Ruiz-Capillas, Claudia; Jiménez-Colmenero, Francisco

    2014-12-01

    The effect of cooking methods (electric grilling and pan-frying in olive oil) on the composition of reduced-fat and reduced-fat/PUFA enriched pork patties was studied. Fat reduction was performed by replacing pork backfat (38% and 100%) with konjac gel and PUFA-enrichment by replacing pork backfat (49%) with a konjac-based oil bulking system stabilizing a healthier oil combination (olive, linseed and fish oils). Cooking losses (13%-27%) were affected (pcooking procedure. Compared with raw products, cooked samples had higher (pcooked, the PUFA levels in the medium-fat/improved sample containing the oil bulking system ranged between 1.4 and 1.6g/100g (0.47-0.51 from n-3 PUFAs), with EPA+DHA concentrations of around 75mg/100g. Konjac materials were successfully used to produce pork patties with a better lipid composition. Copyright © 2014. Published by Elsevier Ltd.

  13. Development and Validation of a Stability-Indicating RP-HPLC Method for Rapid Determination of Doxycycline in Pharmaceutical Bulk and Dosage Forms

    Directory of Open Access Journals (Sweden)

    Shabnam Pourmoslemi, Soroush Mirfakhraee, Saeid Yaripour, Ali Mohammadi

    2016-06-01

    Full Text Available Background: A rapid stability-indicating RP-HPLC method for analysis of doxycycline in the presence of its degradation products was developed and validated. Methods: Forced degradation studies were carried out on bulk samples and capsule dosage forms of doxycycline using acid, base, H2O2, heat, and UV light as described by ICH for stress conditions to demonstrate the stability-indicating power of the method. Separations were performed on a Perfectsil® Target ODS column (3-5µm, 125 mm×4 mm, using a mobile phase consisting of methanol-50 mM ammonium acetate buffer (containing 0.1% v/v trifluoroacetic acid and 0.1% v/v triethylamine, pH 2.5 (50:50 v/v at room temperature. The flow rate was 0.8 mL/min. Results: The method linearity was investigated in the range of 25–500 µg/mL (r > 0.9999. The LOD and LOQ were 5 and 25 µg/mL, respectively. The method selectivity was evaluated by peak purity test using a diode array detector. There was no interference among detection of doxycycline and its stressed degradation products. Total peak purity numbers were in the range of 0.94-0.99, indicating the homogeneity of DOX peaks. Conclusion: These data show the stability-indicating nature of the method for quality control of doxycycline in bulk samples and capsule dosage forms.

  14. Simple method for resistance measurements on thin films and bulk of high T_c superconducting materials

    Science.gov (United States)

    Alzetta, G.; Arimondo, E.; Celli, R. M.; Fuso, F.

    1994-08-01

    Two experimental techniques for measuring resistivity behaviour of high T_c ceramic superconductors in bulk or thin films are described. Particular attention has been given to the development of a four point contact system, easy to use for reliable resistance measurements under repeated, wide thermal cycles. On expose deux méthodes de mesure de la résistivité des supraconducteurs HTc en forme de couches minces déposées sur un substrat ou des céramiques frittées. Le dispositif de mesure, qui a été réalisé avec quatre contacts élastiques, permet d'obtenir des résultats reproductibles dans de très larges intervalles de température.

  15. Grain alignment in bulk YBa2Cu3Ox superconductor by a low temperature phase transformation method

    International Nuclear Information System (INIS)

    Selvamanickam, V.; Goyal, A.; Kroeger, D.M.

    1994-01-01

    A quench and directional phase transformation process has been developed to achieve grain alignment in bulk YBa 2 Cu 3 O x superconductors at temperatures about 100 degree C below the peritectic temperature. Isothermal phase transformation of quenched precursors at 890 degree C for 3 min is found to result in the formation of more than 75% of YBa 2 Cu 3 O x phase without any formation of Y 2 BaCuO 5 . Phase transformation at higher temperatures leads to rapid formation of Y 2 BaCuO 5 in addition to YBa 2 Cu 3 O x . A well-aligned microstructure is achieved by directional phase transformation of the quenched compacts as a rate of 10 mm/h. The magnetic field dependence of the critical current density at 77 K of the directionally phase transformed material compares well with that of melt-textured YBCO and is superior to that of magnetically aligned and sintered YBCO

  16. Flowability of bulk solids used in shale fracturing grouts as determined by the Jenike and Johanson method

    International Nuclear Information System (INIS)

    McDaniel, E.W.; Weeren, H.O.

    1979-09-01

    Smooth operation of the shale fracturing facility at Oak Ridge National Laboratory requires that an even, uninterrupted flow of dry solids be delivered to a mixer at a rate of approximately 1200 lb/min. Some operational difficulties have been experienced with the dry solids system at the existing facility. Occasionally the solids flow from a bin was difficult to initiate or was irregular, particularly when the storage bin was nearly empty. A new shale fracturing facility is now being designed with a solids handling system that will eliminate the current problems. This report describes the tests made to obtain the necessary information about bulk-flow properties of the dry solids that are required for the facility modifications. Flow properties of fly ash, attapulgite, pottery clay, and a blended solids mix were determined in a Jenike and Johanson Flowfactor Tester. Tests with this unit involve the consolidation of a solid at a given pressure and the measurement of the force required to create a shear plane. The procedure is repeated several times at different consolidating pressures to determine a locus of points that can be displayed graphically. Results indicate that a bottom-hopper opening of about 4 ft will be required on the new, bulk storage bins if mass flow is to be achieved. It was also found that the existing bins are quite unsuitable for either their present function or their proposed function. Since these bins have served moderately well for 14 years, the effect of aeration is obviously major; these tests indicate only an upper limit to the size of the hopper opening that will be required. Pottery clay and attapulgite were found to have flow characteristics considerably inferior to blended solids. It is known, however, that attapulgite clay will flow from the existing bins, and modification of the bin bottoms to enlarge the openings does not appear to be justified

  17. Combustion and emissions control in diesel-methane dual fuel engines: The effects of methane supply method combined with variable in-cylinder charge bulk motion

    International Nuclear Information System (INIS)

    Carlucci, Antonio P.; Laforgia, Domenico; Saracino, Roberto; Toto, Giuseppe

    2011-01-01

    Highlights: → We studied dual fuel combustion in diesel engines. → Bulk flow structure of in-cylinder charge and methane supply method were investigated. → Swirl charge motion is capable to enhance air-methane mixture oxidation at low loads. → Methane port injection is capable to reduce unburned hydrocarbons and nitric oxides. - Abstract: In this paper, the results of an extensive experimental campaign about dual fuel combustion development and the related pollutant emissions are reported, paying particular attention to the effect of both the in-cylinder charge bulk motion and methane supply method. A diesel common rail research engine was converted to operate in dual fuel mode and, by activating/deactivating the two different inlet valves of the engine (i.e. swirl and tumble), three different bulk flow structures of the charge were induced inside the cylinder. A methane port injection method was proposed, in which the gaseous fuel was injected into the inlet duct very close to the intake valves, in order to obtain a stratified-like air-fuel mixture up to the end of the compression stroke. For comparison purposes, a homogeneous-like air-fuel mixture was obtained injecting methane more upstream the intake line. Combining the different positions of the methane injector and the three possible bulk flow structures, seven different engine inlet setup were tested. In this way, it was possible to evaluate the effects on dual fuel combustion due to the interaction between methane injector position and charge bulk motion. In addition, methane injection pressure and diesel pilot injection parameters were varied setting the engine at two operating conditions. For some interesting low load tests, the combustion development was studied more in detail by means of direct observation of the process, using an in-cylinder endoscope and a digital CCD camera. Each combustion image was post-processed by a dedicated software, in order to extract only those portions with flame

  18. The measurement of moisture content and dry bulk-density of the top layer of agricultural soils, with minimum calibration, using a gamma-ray attenuation method

    International Nuclear Information System (INIS)

    Van der Westhuizen, M.; Van der Bank, D.J.; Meulke, M.

    1978-06-01

    Various methods of measuring moisture content and dry bulk-density of soil by means of gamma-ray attenuation are discussed. A new method is described in which the same parameters can be measured in consecutive determinations, but for which only one sample of unknown volume is needed for calibration. This method employs a radioactive source in a lead container in an aluminium tube in the soil. From the container the gamma rays follow a path at an angle upwards through the soil towards the detector. The method was tested in a number of experiments and the results are given in tables and graphs. The conclusion is that this method, which is fairly easy and quick to use, is accurate enough for most applications [af

  19. The importance of element speciation in water analysis - a plea for further investigations

    International Nuclear Information System (INIS)

    Frimmel, F.H.; Gremm, T.

    1994-01-01

    Water analysis is dominated by parameters given in laws and recommendations concerning water quality. Speciation has been broadly neglected. This might be due to the difficulties in defining speciation and in determining species at low concentrations. This paper addresses the physical, chemical and biological approaches to speciation and gives examples for methods which are suited for species determination in aquatic systems. Metals and non-metallic elements are covered as well. It is obvious that speciation is a key for understanding the function of aquatic ecosystems and their technical utilization. (orig.)

  20. Spatial and Temporal Variability in Sediment P Distribution and Speciation in Coastal Louisiana

    Science.gov (United States)

    Bowes, K.; White, J. R.; Maiti, K.

    2017-12-01

    Excess loading of phosphorus (P) and nitrogen (N) into aquatic systems leads to degradation of water quality and diminished important ecosystem services. In the Northern Gulf of Mexico (NGOM), excess P and N loading has led to a seasonally present hypoxic area with less than 2 mg/L O2 in bottom waters, approximating 26,000 km2 in 2017. A sequential extraction (SEDEX) method was performed on surficial sediments from five different coastal and shelf sites as a function of distance from the Mississippi River mouth in the NGOM. To better quantify temporal variability in P distribution and speciation, samples were collected during both low (August) and high (May) river flow regimes. Sequential extraction techniques have been successful in separating pools of P into exchangeable or loosely sorbed P, Fe-P, Authigenic-P, Detrital-P, and Organic-P. Preliminary results suggest Authigenic-P is approximately 3-6 times more concentrated in NGOM sediments than all other P pools. Fractionation results did not show a consistent trend with sediment depth. Sediment samples had an average moisture content of 58.72% ± 12.06% and an average bulk density of 0.582 ± 0.275 g/cm3. Continued analysis of P speciation and cycling in NGOM sediments is critical in understanding the driving force behind coastal eutrophication and informing effective nutrient management strategies.

  1. Quantitative comparison of in house irma/ria methods using reagents supplied in bulk with assays based on commercial kits

    International Nuclear Information System (INIS)

    Sajid, K.M.; Jafri, S.R.A.

    1997-01-01

    Due to high cost of commercial kit assays, local trials were started to establish low cost immunoassay techniques at MINAR, Multan. First available alternate of commercial kits was the use of matched reagents supplied in bulk by NETRIA through INMOL, Lahore under IAEA assistance. As quality is crucial in RIA estimations this laboratory collected passive quality control data of 50, 51 and 52 in-house assay batches of T3,T4 and TSH to compare with the same number of last Amerlex RIAs(successive lots). A qualitative comparison based on computerized data analysis shows linear correlation between the results of two assay systems with low and acceptable precision in T3 and T4 assays. In TSH assays both systems show high imprecision although Amerlex RIA system is relatively more precise than in-house TSH- IRMA. T3 and T4 assays in both the systems show wide working ranges covering all clinical regions. In TSH, working ranges of both the techniques do not cover all clinical regions. In-house TSH assay excludes below 5.5 mulU/ml, whereas Amerlex excludes levels below 4.5 mulL/ml. This may reduce the clinical efficacy of these tests. Amerlex-M T3 and T4 assays show high negative drift with relatively less between variation, whereas in-house assays show low positive drift with high between batch variation. (author)

  2. Selenium Speciation and Management in Wet FGD Systems

    Energy Technology Data Exchange (ETDEWEB)

    Searcy, K; Richardson, M; Blythe, G; Wallschlaeger, D; Chu, P; Dene, C

    2012-02-29

    rapidly than it sorbs to ferric solids. Though it was not possible to demonstrate a decrease in selenium concentrations to levels below the project'ale testing were evident at the pilot scale. Specifically, reducing oxidation air rate and ORP tends to either retain selenium as selenite in the liquor or shift selenium phase partitioning to the solid phase. Oxidation air flow rate control may be one option for managing selenium behavior in FGD scrubbers. Units that cycle load widely may find it more difficult to impact ORP conditions with oxidation air flow rate control alone. Because decreasing oxidation air rates to the reaction tank showed that all new selenium reported to the solids, the addition of ferric chloride to the pilot scrubber could not show further improvements in selenium behavior. Ferric chloride addition did shift mercury to the slurry solids, specifically to the fine particles. Several competing pathways may govern the reporting of selenium to the slurry solids: co-precipitation with gypsum into the bulk solids and sorption or co-precipitation with iron into the fine particles. Simultaneous measurement of selenium and mercury behavior suggests a holistic management strategy is best to optimize the fate of both of these elements in FGD waters. Work conducted under this project evaluated sample handling and analytical methods for selenium speciation in FGD waters. Three analytical techniques and several preservation methods were employed. Measurements of selenium speciation over time indicated that for accurate selenium speciation, it is best to conduct measurements on unpreserved, filtered samples as soon after sampling as possible. The capital and operating costs for two selenium management strategies were considered: ferric chloride addition and oxidation air flow rate control. For ferric chloride addition, as might be expected the reagent makeup costs dominate the overall costs, and range from 0.22 to 0.29 mills/kWh. For oxidation air flow rate

  3. Solid phase microextraction speciation analysis of triclosan in aqueous mediacontaining sorbing nanoparticles

    NARCIS (Netherlands)

    Zielinska, K.

    2014-01-01

    Solid phase microextraction (SPME) is applied in the speciation analysis of the hydrophobic compound triclosan in an aqueous medium containing sorbing SiO2 nanoparticles (NPs). It is found that these NPs, as well as their complexes with triclosan, partition between the bulk medium and the solid

  4. Speciation needs in relation with environmental and biological purposes

    International Nuclear Information System (INIS)

    Moulin, V.; Ansoborlo, E.; Bion, L.; Doizi, D.; Moulin, C.; Cote, G.; Madic, C.; Van Der Lee, J.

    2004-01-01

    Radionuclides can occur in the environment either through chronic releases of nuclear facilities, or due to incidents or accidents. In order to study their behaviour in the environment (migration, retention, transfer, and in human organisms (metabolism, retention, excretion), it is of prime importance to know their solution chemistry, and more particularly thermodynamic constants, which will allow to determine their speciation. In fact, speciation governs the migration, the bioavailability and the toxicity of elements. Moreover, this knowledge is also of great interest for decorporation or decontamination purposes. In this framework, a CEA working group on speciation has been created in order to share data both on thermodynamic constants and on speciation analytical methods, interesting chemists, environmentalists and biologists. It has been focused, in a first time, on actinides, namely Th, U, Pu, Am, Np, taking into account their most important oxidation states occurring in environmental or biological environments: Th(IV), U(IV, VI), Pu(III, IV, VI), Am(III), Np(IV, V). A particular attention was devoted to the choice of ligands (inorganic and organic) for being the most representative of environmental and biological media. The thermodynamic database used is BASSIST for Base Applied to Speciation in Solution and at Interfaces and Solubility (developed by CEA), in interaction with the code JCHESS. Different examples will be then presented on the selection of data (thermodynamic constants, ligands of interest) through benchmark exercises (case of U(VI), Am(III), Pu(IV)) which will show the lacks or weakness of knowledge. Speciation diagrams will support these discussions. Moreover, analytical methods to determine thermodynamic constants or direct speciation will also be presented and discussed. (author)

  5. Development of a chromatographic separation method hyphenated to electro-spray ionization mass spectrometry (ESI-MS) and inductively coupled plasma mass spectrometry (ICP-MS): application to the lanthanides speciation analysis

    International Nuclear Information System (INIS)

    Beuvier, Ludovic

    2015-01-01

    This work focuses on the development of a chromatographic separation method coupled to both ESI-MS and ICP-MS in order to achieve the comprehensive speciation analysis of lanthanides in aqueous phase representative of back-extraction phases of advanced spent nuclear fuel treatment processes. This analytical method allowed the separation, the characterization and the quantitation of lanthanides complexes holding poly-aminocarboxylic ligands, such as DTPA and EDTA, used as complexing agents in these processes. A HILIC separation method of lanthanides complexes has been developed with an amide bonded stationary phase. A screening of a wide range of mobile phase compositions demonstrated that the adsorption mechanism was predominant. This screening allowed also obtaining optimized separation conditions. Faster analysis conditions with shorter amide column packed with sub 2 μm particles reduced analysis time by 2.5 and 25% solvent consumption. Isotopic and structural characterization by HILIC ESI-MS was performed as well as the development of external calibration quantitation method. Analytical performances of quantitation method were determined. Finally, the development of the HILIC coupling to ESI-MS and ICP-MS was achieved. A simultaneous quantitation method by ESI-MS and ICP-MS was performed to determine the species quantitative distribution in solution. Analytical performances of quantitation method were also determined. (author) [fr

  6. A NOVEL METHOD FOR QUANTITATIVE DETERMINATION OF ACECLOFENAC IN BULK DRUG AND TABLETS USING SODIUM SALICYLATE AS A HYDROTROPIC SOLUBILIZING AGENT

    Directory of Open Access Journals (Sweden)

    Shruti Moondra

    2010-03-01

    Full Text Available In titrimetric analysis costlier organic solvents are more often employed tosolubilize the poorly water-soluble drugs. Volatility and pollution are drawbacks of suchsolvents. Various techniques are employed to enhance the aqueous solubility of poorlywater-soluble drugs. Hydrotropic solubilization phenomenon has been widely used toenhance the aqueous solubility of large number of poorly water-soluble drugs. Aqueoussolubility of aceclofenac bulk drug [a poorly water-soluble NSAID] was enhanced to agreat extent i.e., 400 folds with 2.5 M sodium salicylate. The primary objective of thepresent investigation was to employ this hydrotropic solution to extract the drug from itsdosage forms, precluding the use of costlier organic solvents. The proposed method ofanalysis is new, simple, accurate, environmentally friendly and reproducible. Statisticaldata proved the accuracy, reproducibility and the precision of the proposed method. Theresults of titrimetric analysis by use of hydrotropy compared very well with the results ofPharmacopoeial method.

  7. X exceptionalism in Caenorhabditis speciation.

    Science.gov (United States)

    Cutter, Asher D

    2017-11-13

    Speciation genetics research in diverse organisms shows the X-chromosome to be exceptional in how it contributes to "rules" of speciation. Until recently, however, the nematode phylum has been nearly silent on this issue, despite the model organism Caenorhabditis elegans having touched most other topics in biology. Studies of speciation with Caenorhabditis accelerated with the recent discovery of species pairs showing partial interfertility. The resulting genetic analyses of reproductive isolation in nematodes demonstrate key roles for the X-chromosome in hybrid male sterility and inviability, opening up new understanding of the genetic causes of Haldane's rule, Darwin's corollary to Haldane's rule, and enabling tests of the large-X effect hypothesis. Studies to date implicate improper chromatin regulation of the X-chromosome by small RNA pathways as integral to hybrid male dysfunction. Sexual transitions in reproductive mode to self-fertilizing hermaphroditism inject distinctive molecular evolutionary features into the speciation process for some species. Caenorhabditis also provides unique opportunities for analysis in a system with XO sex determination that lacks a Y-chromosome, sex chromosome-dependent sperm competition differences and mechanisms of gametic isolation, exceptional accessibility to the development process and rapid experimental evolution. As genetic analysis of reproductive isolation matures with investigation of multiple pairs of Caenorhabditis species and new species discovery, nematodes will provide a powerful complement to more established study organisms for deciphering the genetic basis of and rules to speciation. © 2017 John Wiley & Sons Ltd.

  8. CHURCH, Category, and Speciation

    Directory of Open Access Journals (Sweden)

    Rinderknecht Jakob Karl

    2018-01-01

    Full Text Available The Roman Catholic definition of “church”, especially as applied to groups of Protestant Christians, creates a number of well-known difficulties. The similarly complex category, “species,” provides a model for applying this term so as to neither lose the centrality of certain examples nor draw a hard boundary to rule out border cases. In this way, it can help us to more adequately apply the complex ecclesiology of the Second Vatican Council. This article draws parallels between the understanding of speciation and categorization and the definition of Church since the council. In doing so, it applies the work of cognitive linguists, including George Lakoff, Zoltan Kovecses, Giles Fauconnier and Mark Turner on categorization. We tend to think of categories as containers into which we sort objects according to essential criteria. However, categories are actually built inductively by making associations between objects. This means that natural categories, including species, are more porous than we assume, but nevertheless bear real meaning about the natural world. Taxonomists dispute the border between “zebras” and “wild asses,” but this distinction arises out of genetic and evolutionary reality; it is not merely arbitrary. Genetic descriptions of species has also led recently to the conviction that there are four species of giraffe, not one. This engagement will ground a vantage point from which the Council‘s complex ecclesiology can be more easily described so as to authentically integrate its noncompetitive vision vis-a-vis other Christians with its sense of the unique place held by Catholic Church.

  9. Cancer: beyond speciation.

    Science.gov (United States)

    Vincent, Mark D

    2011-01-01

    A good account of the nature of cancer should provide not only a description of its consistent features, but also how they arise, how they are maintained, why conventional chemotherapy succeeds, and fails, and where to look for better targets. Cancer was once regarded as enigmatic and inexplicable; more recently, the "mutation theory," based on random alterations in a relatively small set of proto-oncogenes and tumor suppressor genes, has enjoyed widespread acceptance. The "mutation theory," however, is noticeable for its failure to explain the basis of differential chemosensitivity, for providing a paucity of targets, especially druggable ones, and for justifying the development of targeted therapies with, in general, disappointingly abbreviated clinical benefit. Furthermore, this theory has mistakenly predicted a widespread commonality of consistent genetic abnormalities across the range of cancers, whereas the opposite, that is, roiling macrogenomic instability, is generally the rule. In contrast, concerning what actually is consistent, that is, the suite of metabolic derangements common to virtually all, especially aggressive, cancers, the "Mutation Theory" has nothing to say. Other hypotheses merit serious consideration "aneuploidy theories" posit whole-genome instability and imbalance as causally responsible for the propagation of the tumor. Another approach, that is, "derepression atavism," suggests cancer results from the release of an ancient survival program, characterized by the emergence of remarkably primitive features such as unicellularity, fermentation, and immortality; existential goals are served by heuristic genomic instability coupled with host-to-tumor biomass interconversion, mediated by the Warburg effect, a major component of the program. Carcinogenesis is here seen as a process of de-speciation; however, genomic nonrestabilization raises issues as to where on the tree of life cancers belong, as a genuinely alternative modus vivendi

  10. Speciation analysis of 129I in seawater using coprecipitation and accelerator mass spectrometry and its applications

    DEFF Research Database (Denmark)

    Xing, Shan; Hou, Xiaolin; Aldahan, Ala

    2017-01-01

    Speciation analysis of long-lived 129I in seawater can provide useful information on the source of water masses. This paper presents an improved method for speciation analysis of 129I based on coprecipitation of iodide as AgI with Ag2SO3 and AgCl. By adding a small amount of 127I carrier...

  11. Sympatric Speciation in Threespine Stickleback: Why Not?

    Directory of Open Access Journals (Sweden)

    Daniel I. Bolnick

    2011-01-01

    Full Text Available Numerous theoretical models suggest that sympatric speciation is possible when frequency-dependent interactions such as intraspecific competition drive disruptive selection on a trait that is also subject to assortative mating. Here, I review recent evidence that both conditions are met in lake populations of threespine stickleback (Gasterosteus aculeatus. Nonetheless, sympatric speciation appears to be rare or absent in stickleback. If stickleback qualitatively fit the theoretical requirements for sympatric speciation, why do they not undergo sympatric speciation? I present simulations showing that disruptive selection and assortative mating in stickleback, though present, are too weak to drive speciation. Furthermore, I summarize empirical evidence that disruptive selection in stickleback drives other forms of evolutionary diversification (plasticity, increased trait variance, and sexual dimorphism instead of speciation. In conclusion, core assumptions of sympatric speciation theory seem to be qualitatively reasonable for stickleback, but speciation may nevertheless fail because of (i quantitative mismatches with theory and (ii alternative evolutionary outcomes.

  12. Spectrophotometric and spectrofluorimetric methods for determination of certain biologically active phenolic drugs in their bulk powders and different pharmaceutical formulations

    Science.gov (United States)

    Omar, Mahmoud A.; Badr El-Din, Kalid M.; Salem, Hesham; Abdelmageed, Osama H.

    2018-03-01

    Two simple and sensitive spectrophotometric and spectrofluorimetric methods for the determination of terbutaline sulfate, fenoterol hydrobromide, etilefrine hydrochloride, isoxsuprine hydrochloride, ethamsylate, doxycycline hyclate have been developed. Both methods were based on the oxidation of the cited drugs with cerium (IV) in acid medium. The spectrophotometric method was based on measurement of the absorbance difference (ΔA), which represents the excess cerium (IV), at 317 nm for each drug. On the other hand, the spectrofluorimetric method was based on measurement of the fluorescent of the produced cerium (III) at emission wavelength 354 nm (λexcitation = 255 nm) for the concentrations studied for each drug. For both methods, the variables affecting the reactions were carefully investigated and the conditions were optimized. Linear relationships were found between either ΔA or the fluorescent of the produced cerium (III) values and the concentration of the studied drugs in a general concentration range of 2.0-24.0 μg mL- 1, 20.0-24.0 ng mL- 1 with good correlation coefficients in the following range 0.9990-0.9999, 0.9990-0.9993 for spectrophotometric and spectrofluorimetric methods respectively. The limits of detection and quantitation of spectrophotometric method were found in general concentration range 0.190-0.787 and 0.634-2.624 μg mL- 1respectively. For spectrofluorimetric method, the limits of detection and quantitation were found in general concentration range 4.77-9.52 and 15.91-31.74 ng mL- 1 respectively. The stoichiometry of the reaction was determined, and the reactions pathways were postulated. The analytical performance of the methods, in terms of accuracy and precision, were statistically validated and the results obtained were satisfactory. The methods have been successfully applied to the determination of the cited drugs in their commercial pharmaceutical formulations. Statistical comparison of the results with the reference methods

  13. Stability indicating RP-HPLC method for simultaneous determination of pantoprazole sodium and itopride hydrochloride in bulk and capsule

    Directory of Open Access Journals (Sweden)

    Krishna R. Gupta

    2011-03-01

    Full Text Available A stability indicating reversed-phase HPLC method has been developed and subsequently validated for simultaneous estimation of pantoprazole present as pantoprazole sodium sesquihydrate (PSS, and itopride hydrochloride from their combination product. The proposed RP-HPLC method utilizes a Phenomenex® C18, 5 µm, 250 mm X 4.6 mm i.d. column, mobile phase consisting of phosphate buffer and acetonitrile in the proportion of 55:45 (v/v with apparent pH adjusted to 5.0, and UV detection at 289.0 nm using a UV detector. PAN, ITH and their combination drug product were exposed to thermal, photolytic, hydrolytic and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. The described method was linear over a range of 4-20 µg/mL for PAN and 15-75 µg/mL for ITH. The mean recoveries were 100.02 and 99.88 for PAN and ITH, respectively. Chromatographic peak purity data of PAN and ITH indicated no co-eluting peaks with the main peaks of drugs which demonstrated the specificity of assay method for their estimation in presence of degradation products. The proposed method can be useful in the quality control of combination drug products.

  14. Extensive range overlap between heliconiine sister species: evidence for sympatric speciation in butterflies?

    Science.gov (United States)

    Rosser, Neil; Kozak, Krzysztof M; Phillimore, Albert B; Mallet, James

    2015-06-30

    Sympatric speciation is today generally viewed as plausible, and some well-supported examples exist, but its relative contribution to biodiversity remains to be established. We here quantify geographic overlap of sister species of heliconiine butterflies, and use age-range correlations and spatial simulations of the geography of speciation to infer the frequency of sympatric speciation. We also test whether shifts in mimetic wing colour pattern, host plant use and climate niche play a role in speciation, and whether such shifts are associated with sympatry. Approximately a third of all heliconiine sister species pairs exhibit near complete range overlap, and analyses of the observed patterns of range overlap suggest that sympatric speciation contributes 32%-95% of speciation events. Müllerian mimicry colour patterns and host plant choice are highly labile traits that seem to be associated with speciation, but we find no association between shifts in these traits and range overlap. In contrast, climatic niches of sister species are more conserved. Unlike birds and mammals, sister species of heliconiines are often sympatric and our inferences using the most recent comparative methods suggest that sympatric speciation is common. However, if sister species spread rapidly into sympatry (e.g. due to their similar climatic niches), then assumptions underlying our methods would be violated. Furthermore, although we find some evidence for the role of ecology in speciation, ecological shifts did not show the associations with range overlap expected under sympatric speciation. We delimit species of heliconiines in three different ways, based on "strict and " "relaxed" biological species concepts (BSC), as well as on a surrogate for the widely-used "diagnostic" version of the phylogenetic species concept (PSC). We show that one reason why more sympatric speciation is inferred in heliconiines than in birds may be due to a different culture of species delimitation in the two

  15. Characteristics of a Bulk High-Critical Temperature Superconductor Fabricated by the Shock Compaction Method: Possible Use as a Highly Sensitive Magnetic Sensor

    International Nuclear Information System (INIS)

    Fujita, H; Maeji, Y; Yamagata, K; Itoh, M; Kezuka, H; Kikuchi, M; Atou, T; Kawasaki, M; Fukuoka, K

    2006-01-01

    A magnetic sensor, constructed of bulk Bi-Pb-Sr-Ca-Cu-O (BPSCCO), was fabricated by use of the shock compaction method, employing a propellant gun-system, and then sintered under through use of an electronic furnace. The specimen as a magnetic sensor was maintained in the superconducting state at 77.4 K, under a current density J of approximately 40 A/cm 2 in the absence of an excitation magnetic field B ex . The superconducting state was then broken and the specimen exposed to a B ex value of 40x10 -4 T. That is, the resistance R meas of the specimen occurred when exposed to 40x10 -4 T under a constant J of 40 A/cm 2 . The magnetic sensitivity S of the specimen was approximately 13 %/(10 -4 T) over the range of measurement of the magnetic field B meas from 0 to ±5x10 -4 T, under a constant 40x10 -4 T for the value of B ex , being approximately 13 times greater than that of a giant magnetoresistance (GMR) sensor. It was, consequently, determined that it was possible to apply the bulk BPSCCO specimen as a highly sensitive magnetic sensor

  16. Characteristics of a Bulk High-Critical Temperature Superconductor Fabricated by the Shock Compaction Method: Possible Use as a Highly Sensitive Magnetic Sensor

    Energy Technology Data Exchange (ETDEWEB)

    Fujita, H [Interdisci. Grad. School of Sci. and Engi., Grad. School of Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan); Maeji, Y [Interdisci. Grad. School of Sci. and Engi., Grad. School of Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan); Yamagata, K [Relia. Eval. Technol. Center, Nitto Denko Corp., Onomichi, Hiroshima 722-0212 (Japan); Itoh, M [Interdisci. Grad. School of Sci. and Engi., Grad. School of Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan); Kezuka, H [Faculty of Bionics, Tokyo University of Technol., Hachioji, Tokyo 192-0982 (Japan); Kikuchi, M [Kansen Fukushi Research Center, Tohoku Fukushi University Sendai, Miyagi 989-3201 (Japan); Atou, T [Insti. for Mate. Research, Tohoku University Sendai, Miyagi 980-8577 (Japan); Kawasaki, M [Insti. for Mate. Research, Tohoku University Sendai, Miyagi 980-8577 (Japan); Fukuoka, K [Insti. for Mate. Research, Tohoku University Sendai, Miyagi 980-8577 (Japan)

    2006-06-01

    A magnetic sensor, constructed of bulk Bi-Pb-Sr-Ca-Cu-O (BPSCCO), was fabricated by use of the shock compaction method, employing a propellant gun-system, and then sintered under through use of an electronic furnace. The specimen as a magnetic sensor was maintained in the superconducting state at 77.4 K, under a current density J of approximately 40 A/cm{sup 2} in the absence of an excitation magnetic field B{sub ex}. The superconducting state was then broken and the specimen exposed to a B{sub ex} value of 40x10{sup -4} T. That is, the resistance R{sub meas} of the specimen occurred when exposed to 40x10{sup -4} T under a constant J of 40 A/cm{sup 2}. The magnetic sensitivity S of the specimen was approximately 13 %/(10{sup -4} T) over the range of measurement of the magnetic field B{sub meas} from 0 to {+-}5x10{sup -4} T, under a constant 40x10{sup -4} T for the value of B{sub ex}, being approximately 13 times greater than that of a giant magnetoresistance (GMR) sensor. It was, consequently, determined that it was possible to apply the bulk BPSCCO specimen as a highly sensitive magnetic sensor.

  17. A validated RP-HPLC method for simultaneous determination of propranolol and valsartan in bulk drug and gel formulation

    Science.gov (United States)

    Imam, Syed Sarim; Ahad, Abdul; Aqil, Mohammed; Sultana, Yasmin; Ali, Asgar

    2013-01-01

    Objective: A simple, precise, and stability indicating high performance liquid chromatography (HPLC) method was developed and validated for the simultaneous determination of propranolol hydrochloride and valsartan in pharmaceutical dosage form. Materials and Methods: The method involves the use of easily available inexpensive laboratory reagents. The separation was achieved on Hypersil ODS C-18 column (250*4.6 mm, i.d., 5 μm particle size) with isocratic flow with UV detector. The mobile phase at a flow rate of 1.0 mL/min consisted of acetonitrile, methanol, and 0.01 M disodium hydrogen phosphate (pH 3.5) in the ratio of 50:35:15 v/v. Results: A linear response was observed over the concentration range 5-50 μg/mL of propranolol and the concentration range 4-32 μg/mL of valsartan. Limit of detection and limit of quantitation for propranolol were 0.27 μg/mL and 0.85 μg/mL, and for valsartan were 0.45 μg/mL and 1.39 μg/mL, respectively. The method was successfully validated in accordance to ICH guidelines acceptance criteria for linearity, accuracy, precision, specificity, robustness. Conclusion: The analysis concluded that the method was selective for simultaneous estimation of propranolol and valsartan can be potentially used for the estimation of these drugs in combined dosage form. PMID:23559826

  18. New Stability Indicating RP-HPLC Method for the Estimation of Cefpirome Sulphate in Bulk and Pharmaceutical Dosage Forms

    OpenAIRE

    Rao, Kareti Srinivasa; Kumar, Keshar Nargesh; Joydeep, Datta

    2011-01-01

    A simple stability indicating reversed-phase HPLC method was developed and subsequently validated for estimation of Cefpirome sulphate (CPS) present in pharmaceutical dosage forms. The proposed RP-HPLC method utilizes a LiChroCART-Lichrosphere100, C18 RP column (250 mm ? 4mm ? 5 ?m) in an isocratic separation mode with mobile phase consisting of methanol and water in the proportion of 50:50 % (v/v), at a flow rate 1ml/min, and the effluent was monitored at 270 nm. The retention time of CPS wa...

  19. New Stability Indicating RP-HPLC Method for the Estimation of Cefpirome Sulphate in Bulk and Pharmaceutical Dosage Forms.

    Science.gov (United States)

    Rao, Kareti Srinivasa; Kumar, Keshar Nargesh; Joydeep, Datta

    2011-01-01

    A simple stability indicating reversed-phase HPLC method was developed and subsequently validated for estimation of Cefpirome sulphate (CPS) present in pharmaceutical dosage forms. The proposed RP-HPLC method utilizes a LiChroCART-Lichrosphere100, C18 RP column (250 mm × 4mm × 5 μm) in an isocratic separation mode with mobile phase consisting of methanol and water in the proportion of 50:50 % (v/v), at a flow rate 1ml/min, and the effluent was monitored at 270 nm. The retention time of CPS was 2.733 min and its formulation was exposed to acidic, alkaline, photolytic, thermal and oxidative stress conditions, and the stressed samples were analyzed by the proposed method. The described method was linear over a range of 0.5-200μg/ml. The percentage recovery was 99.46. F-test and t-test at 95% confidence level were used to check the intermediate precision data obtained under different experimental setups; the calculated value was found to be less than the critical value.

  20. Bulk derivatization and cation exchange restricted access media-based trap-and-elute liquid chromatography–mass spectrometry method for determination of trace estrogens in serum

    International Nuclear Information System (INIS)

    Beinhauer, Jana; Bian, Liangqiao; Fan, Hui; Šebela, Marek; Kukula, Maciej; Barrera, Jose A.

    2015-01-01

    Highlights: • Analysis of estrogens in small volume samples at low parts-per-trillion concentration. • Charged bulk derivatization facilitates on-line ion exchange sample preparation. • On-line WCX restricted access media traps analytes, but not proteins and lipids. • Complete preparation and LC–MS/MS analysis completed in 30 min/sample. - Abstract: Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p-toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL −1 , and demonstrated good linearity of R 2 from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL −1 . Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified

  1. Speciation of animal fat: Needs and challenges.

    Science.gov (United States)

    Hsieh, Yun-Hwa Peggy; Ofori, Jack Appiah

    2017-05-24

    The use of pork fat is a concern for Muslims and Jews, who for religious reasons avoid consuming anything that is pig-derived. The use of bovine materials, including beef fat, is prohibited in Hinduism and may also pose a risk of carrying the infectious agent for bovine spongiform encephalopathy. Vegetable oils are sometimes adulterated with animal fat or pork fat with beef fat for economic gain. The development of methods to determine the species origin of fat has therefore become a priority due to the complex and global nature of the food trade, which creates opportunities for the fraudulent use of these animal fats as food ingredients. However, determining the species origin of fats in processed foods or composite blends is an arduous task as the adulterant has a composition that is very similar to that of the original fat or oil. This review examines some of the methods that have been developed for fat speciation, including both fat-based and DNA-based methods, their shortcomings, and the need for additional alternatives. Protein-based methods, specifically immunoassays targeting residual proteins in adipose tissue, that are being explored by researchers as a new tool for fat speciation will also be discussed.

  2. Azeotropic mixture used for development and validation of Lornoxicam in bulk and its tablet dosage form by spectrophotometric method

    Directory of Open Access Journals (Sweden)

    Prajesh Prajapati

    2012-08-01

    Full Text Available A novel, safe, economic and sensitive method of spectrophotometric estimation has been developed using Azeoptropic mixture (water:methanol: 60:40, v/v for the quantitative determination of Lornoxicam, a practically water-insoluble drug. Hence, Lornoxicam stock solution was prepared in Azeoptropic mixture. Lornoxicam showed maximum absorbance at 383 nm. Beer's law was obeyed in the concentration range 4–24 μg/mL with regression coefficient of 0.999. The method was validated in terms of linearity (R2=0.999, precision (CV for intra-day and inter-day was 0.28–0.68 and 0.12–0.92, respectively, accuracy (98.03–100.59% w/w and specificity. This method is simple, precise, accurate, sensitive and reproducible and can be used for the routine quality control testing of the marketed formulations. Keywords: Analgesic, Chlortenoxicam, Lornoxicam, Oxicam, Spectrophotometric, Azeotropic mixture

  3. Neutral Models with Generalised Speciation

    NARCIS (Netherlands)

    Haegeman, Bart; Etienne, Rampal S.

    Hubbell's neutral theory claims that ecological patterns such as species abundance distributions can be explained by a stochastic model based on simple assumptions. One of these assumptions, the point mutation assumption, states that every individual has the same probability to speciate. Etienne et

  4. Investigating ecological speciation in non-model organisms

    DEFF Research Database (Denmark)

    Foote, Andrew David

    2012-01-01

    Background: Studies of ecological speciation tend to focus on a few model biological systems. In contrast, few studies on non-model organisms have been able to infer ecological speciation as the underlying mechanism of evolutionary divergence. Questions: What are the pitfalls in studying ecological...... speciation in non-model organisms that lead to this bias? What alternative approaches might redress the balance? Organism: Genetically differentiated types of the killer whale (Orcinus orca) exhibiting differences in prey preference, habitat use, morphology, and behaviour. Methods: Review of the literature...... on killer whale evolutionary ecology in search of any difficulty in demonstrating causal links between variation in phenotype, ecology, and reproductive isolation in this non-model organism. Results: At present, we do not have enough evidence to conclude that adaptive phenotype traits linked to ecological...

  5. Liquid chromatographic method for simultaneous determination of citalopram with NSAIDs in bulk drug, pharmaceutical formulation and human serum

    International Nuclear Information System (INIS)

    Ali, S.N.; Akram, S.

    2017-01-01

    A high performance liquid chromatographic method was developed and validated to simultaneously quantify citalopram with piroxicam, celecoxib and diclofenac sodium. Chromatographic analysis was performed at ambient temperature using Shimadzu Shim-pack CLC-ODS (M) 25M column linked to a UV-visible detector adjusted at 230 nm, employing 80:20 (v/v) methanol: water (pH 3.5) as mobile phase with flow rate 1.0 mL min-1. Validation was performed in the ranges 0.6-20, 0.9-28, 0.6-20 and 1.0-32 mu g mL-1 with lowest level corresponding to detection limit 16.45, 23.33, 27.66 and 14.44 ng mL-1 respectively. With-in the day precision ranged from 0.14-1.67% and between-day precision from 0.40-1.50%, accuracies were 99.61-100.86%. The analytes were successfully detected without any observable interference in pharmaceutical formulation and human serum samples demonstrating effectiveness of method. (author)

  6. Stability-indicating liquid chromatographic method for quantification of new anti-epileptic drug lacosamide in bulk and pharmaceutical formulation

    Directory of Open Access Journals (Sweden)

    Chhalotiya Usmangani K.

    2012-01-01

    Full Text Available An isocratic stability indicating reversed-phase liquid chromatographic determination was developed for the quantitative determination of lacosamide in the pharmaceutical dosage form. A Hypersil C-18, 4.5μm column with mobile phase containing acetonitrile-water (20:80, v/v was used. The flow rate was 1.0 mL min-1 and effluents were monitored at 258 nm. The retention time of lacosamide was 8.9 min. The method was found to be linear in the concentration range of 5-100 μg/ml and the recovery was found to be in the range of 99.15 - 100.09 %. The limit of detection and limit of quantification were found to be 2 μg/ml and 5 μg/ml, respectively. Lacosamide stock solutions were subjected to acid and alkali hydrolysis, chemical oxidation and dry heat degradation. The drug was found to be stable to the dry heat and acidic condition attempted. The proposed method was validated and successfully applied to the estimation of lacosamide in tablet dosage forms.

  7. Development and validation of a stability-indicating RP–HPLC method for estimation of atazanavir sulfate in bulk

    Directory of Open Access Journals (Sweden)

    S. Dey

    2017-04-01

    Full Text Available A stability-indicating reverse phase–high performance liquid chromatography (RP–HPLC method was developed and validated for the determination of atazanavir sulfate in tablet dosage forms using C18 column Phenomenix (250 mm×4.6 mm, 5 μm with a mobile phase consisting of 900 mL of HPLC grade methanol and 100 mL of water of HPLC grade. The pH was adjusted to 3.55 with acetic acid. The mobile phase was sonicated for 10 min and filtered through a 0.45 μm membrane filter at a flow rate of 0.5 mL/min. The detection was carried out at 249 nm and retention time of atazanavir sulfate was found to be 8.323 min. Linearity was observed from 10 to 90 μg/mL (coefficient of determination R2 was 0.999 with equation, y=23.427x+37.732. Atazanavir sulfate was subjected to stress conditions including acidic, alkaline, oxidation, photolysis and thermal degradation, and the results showed that it was more sensitive towards acidic degradation. The method was validated as per ICH guidelines.

  8. The EU network on trace element speciation in full swing

    DEFF Research Database (Denmark)

    Cornelis, R.; Camara, C.; Ebdon, L.

    2000-01-01

    health and hygiene. The network covers a number of important issues including organotin compounds, chromium and nickel species, chemical characterisation of environmental and industrial particulate samples, risk assessment, selenium and a series of other essential and toxic elements in food, as well......The EC-funded thematic network 'Speciation 21' links scientists in analytical chemistry working in method development for the chemical speciation of trace elements, and potential users from industry and representatives of legislative agencies, in the field of environment, food and occupational...

  9. Speciation of Long-Lived Radionuclides in the Environment

    DEFF Research Database (Denmark)

    Hou, Xiaolin

    , isotopes of Pu, and 237Np in seawater, fresh water, soil, sediment, vegetations, and concrete. The developed methods are used for the investigation of the chemical speciation of these radionuclides as well as their environmental behaviours, especially in Danish environment. In addition the speciation of Pu...... isotopes in waste samples from the decommissioning of Danish nuclear facilities is also investigated. The report summarizes these works completed in this project. Through this research project, a number of research papers have been published in the scientific journals, the research results has also been...

  10. Optimization of Forced Degradation Using Experimental Design and Development of a Stability-Indicating Liquid Chromatographic Assay Method for Rebamipide in Bulk and Tablet Dosage Form

    Directory of Open Access Journals (Sweden)

    Sandeep SONAWANE

    2016-09-01

    Full Text Available A novel stability-indicating RP-HPLC assay method was developed and validated for quantitative determination of rebamipide in bulk and tablet dosage form. Rebamipide (drug and drug product solutions were exposed to acid and alkali hydrolysis, thermal stress, oxidation by hydrogen peroxide and photodegradation. Experimental design has been used during forced degradation to determine significant factors responsible for degradation and to obtain optimal degradation conditions. In addition, acid and alkali hydrolysis was performed using a microwave oven. The chromatographic method employed the HiQ sil C-18HS (250 × 4.6 mm; 5 μm column with mobile phase consisting of 0.02 M potassium phosphate (pH adjusted to 6.8 and methanol (40:60, v/v and the detection was performed at 230 nm. The procedure was validated for specificity, linearity, accuracy, precision and robustness. There was no interference observed of excipients and degradation products in the determination of the active pharmaceutical ingredient. The method showed good accuracy and precision (intra and inter day and the response was linear in a range from 0.5 to 5 μg mL−1. The method was found to be simple and fast with less trial and error experimentation by making use of experimental design. Also, it proved that microwave energy can be used to expedite hydrolysis of rebamipide.

  11. A Simple and Specific Stability- Indicating RP-HPLC Method for Routine Assay of Adefovir Dipivoxil in Bulk and Tablet Dosage Form.

    Science.gov (United States)

    Darsazan, Bahar; Shafaati, Alireza; Mortazavi, Seyed Alireza; Zarghi, Afshin

    2017-01-01

    A simple and reliable stability-indicating RP-HPLC method was developed and validated for analysis of adefovir dipivoxil (ADV).The chromatographic separation was performed on a C 18 column using a mixture of acetonitrile-citrate buffer (10 mM at pH 5.2) 36:64 (%v/v) as mobile phase, at a flow rate of 1.5 mL/min. Detection was carried out at 260 nm and a sharp peak was obtained for ADV at a retention time of 5.8 ± 0.01 min. No interferences were observed from its stress degradation products. The method was validated according to the international guidelines. Linear regression analysis of data for the calibration plot showed a linear relationship between peak area and concentration over the range of 0.5-16 μg/mL; the regression coefficient was 0.9999and the linear regression equation was y = 24844x-2941.3. The detection (LOD) and quantification (LOQ) limits were 0.12 and 0.35 μg/mL, respectively. The results proved the method was fast (analysis time less than 7 min), precise, reproducible, and accurate for analysis of ADV over a wide range of concentration. The proposed specific method was used for routine quantification of ADV in pharmaceutical bulk and a tablet dosage form.

  12. Analytical Method Development and Validation for the Simultaneous Estimation of Abacavir and Lamivudine by Reversed-phase High-performance Liquid Chromatography in Bulk and Tablet Dosage Forms.

    Science.gov (United States)

    Raees Ahmad, Sufiyan Ahmad; Patil, Lalit; Mohammed Usman, Mohammed Rageeb; Imran, Mohammad; Akhtar, Rashid

    2018-01-01

    A simple rapid, accurate, precise, and reproducible validated reverse phase high performance liquid chromatography (HPLC) method was developed for the determination of Abacavir (ABAC) and Lamivudine (LAMI) in bulk and tablet dosage forms. The quantification was carried out using Symmetry Premsil C18 (250 mm × 4.6 mm, 5 μm) column run in isocratic way using mobile phase comprising methanol: water (0.05% orthophosphoric acid with pH 3) 83:17 v/v and a detection wavelength of 245 nm and injection volume of 20 μl, with a flow rate of 1 ml/min. In the developed method, the retention times of ABAC and LAMI were found to be 3.5 min and 7.4 min, respectively. The method was validated in terms of linearity, precision, accuracy, limits of detection, limits of quantitation, and robustness in accordance with the International Conference on Harmonization guidelines. The assay of the proposed method was found to be 99% - 101%. The recovery studies were also carried out and mean % recovery was found to be 99% - 101%. The % relative standard deviation from reproducibility was found to be performance liquid chromatography, UV: Ultraviolet, ICH: International Conference on Harmonization, ABAC: Abacavir, LAMI: Lamivudine, HIV: Human immunodeficiency virus, AIDS: Acquired immunodeficiency syndrome, NRTI: Nucleoside reverse transcriptase inhibitors, ARV: Antiretroviral, RSD: Relative standard deviation, RT: Retention time, SD: Standard deviation.

  13. Relative Bioavailability and Bioaccessability and Speciation of ...

    Science.gov (United States)

    Background: Assessment of soil arsenic (As) bioavailability may profoundly affect the extent of remediation required at contaminated sites by improving human exposure estimates. Because small adjustments in soil As bioavailability estimates can significantly alter risk assessments and remediation goals, convenient, rapid, reliable, and inexpensive tools are needed to determine soil As bioavailability. Objectives: We evaluated inexpensive methods for assessing As bioavailability in soil as a means to improve human exposure estimates and potentially reduce remediation costs. Methods: Nine soils from residential sites affected by mining or smelting activity and two National Institute of Standards and Technology standard reference materials were evaluated for As bioavailability, bioaccessibility, and speciation. Arsenic bioavailability was determined using an in vivo mouse model, and As bioaccessibility was determined using the Solubility/Bioavailability Research Consortium in vitro assay. Arsenic speciation in soil and selected soil physicochemical properties were also evaluated to determine whether these parameters could be used as predictors of As bio¬availability and bioaccessibility. Results: In the mouse assay, we compared bioavailabilities of As in soils with that for sodium arsenate. Relative bioavailabilities (RBAs) of soil As ranged from 11% to 53% (mean, 33%). In vitro soil As bioaccessibility values were strongly correlated with soil As RBAs (R

  14. Resolving uncertainty in chemical speciation determinations

    Science.gov (United States)

    Smith, D. Scott; Adams, Nicholas W. H.; Kramer, James R.

    1999-10-01

    Speciation determinations involve uncertainty in system definition and experimentation. Identification of appropriate metals and ligands from basic chemical principles, analytical window considerations, types of species and checking for consistency in equilibrium calculations are considered in system definition uncertainty. A systematic approach to system definition limits uncertainty in speciation investigations. Experimental uncertainty is discussed with an example of proton interactions with Suwannee River fulvic acid (SRFA). A Monte Carlo approach was used to estimate uncertainty in experimental data, resulting from the propagation of uncertainties in electrode calibration parameters and experimental data points. Monte Carlo simulations revealed large uncertainties present at high (>9-10) and low (monoprotic ligands. Least-squares fit the data with 21 sites, whereas linear programming fit the data equally well with 9 sites. Multiresponse fitting, involving simultaneous fluorescence and pH measurements, improved model discrimination. Deconvolution of the excitation versus emission fluorescence surface for SRFA establishes a minimum of five sites. Diprotic sites are also required for the five fluorescent sites, and one non-fluorescent monoprotic site was added to accommodate the pH data. Consistent with greater complexity, the multiresponse method had broader confidence limits than the uniresponse methods, but corresponded better with the accepted total carboxylic content for SRFA. Overall there was a 40% standard deviation in total carboxylic content for the multiresponse fitting, versus 10% and 1% for least-squares and linear programming, respectively.

  15. Fractionation, characterization and speciation of heavy metals in ...

    African Journals Online (AJOL)

    Speciation of heavy metals in soils determines the availability for metals for plant uptake and potential for contamination of groundwater following application of composts to agricultural lands. Methods used to characterize heavy metals in solid phase of composts and compost amended soils include physical fractionation ...

  16. Speciation of Zinc Mixed Ligand Complexes in Salt Water Systems ...

    African Journals Online (AJOL)

    Speciation of Zinc Mixed Ligand Complexes in Salt Water Systems. ... method has been used to study heavy metal interaction in model lake water in KNO3 ... is of no consequential effect because in its normal state, the [OH-] of the lake water is ...

  17. Speciation and migration of 129I in soil profiles

    DEFF Research Database (Denmark)

    Luo, Maoyi; Hou, Xiaolin; Zhou, Weijian

    2013-01-01

    A method has been developed for speciation analysis of ultra low level 129I in soil using sequential extraction combined with coprecipitation for separation of carrier free iodine and AMS measurement of 129I. Two loess profiles collected from northwest China were analyzed for species of 129I...

  18. Bulk oil clauses

    International Nuclear Information System (INIS)

    Gough, N.

    1993-01-01

    The Institute Bulk Oil Clauses produced by the London market and the American SP-13c Clauses are examined in detail in this article. The duration and perils covered are discussed, and exclusions, adjustment clause 15 of the Institute Bulk Oil Clauses, Institute War Clauses (Cargo), and Institute Strikes Clauses (Bulk Oil) are outlined. (UK)

  19. Bulk derivatization and cation exchange restricted access media-based trap-and-elute liquid chromatography–mass spectrometry method for determination of trace estrogens in serum

    Energy Technology Data Exchange (ETDEWEB)

    Beinhauer, Jana [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Bian, Liangqiao [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Fan, Hui [Department of Chemistry and Biochemistry, The University of Texas at Arlington, Arlington, TX (United States); Šebela, Marek [Department of Biochemistry, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Centre of the Region Haná for Biotechnological and Agricultural Research - Department of Protein Biochemistry and Proteomics, Faculty of Science, Palacký University, Šlechtitelů 11, CZ-783 71 Olomouc (Czech Republic); Kukula, Maciej [Shimadzu Center for Advanced Analytical Chemistry, The University of Texas at Arlington, Arlington, TX (United States); Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); Barrera, Jose A. [Shimadzu Institute for Research Technologies, The University of Texas at Arlington, Arlington, TX (United States); and others

    2015-02-09

    Highlights: • Analysis of estrogens in small volume samples at low parts-per-trillion concentration. • Charged bulk derivatization facilitates on-line ion exchange sample preparation. • On-line WCX restricted access media traps analytes, but not proteins and lipids. • Complete preparation and LC–MS/MS analysis completed in 30 min/sample. - Abstract: Estrone (E1), estradiols (α/β-E2), and estriol (E3) are four major metabolically active estrogens exerting strong biological activities at very low circulating concentrations. This paper reports a sensitive and efficient method with automated, on-line clean-up and detection to determine trace estrogens in a small volume of serum samples using liquid chromatography–electrospray ionization–tandem mass spectrometry directly, without off-line liquid–liquid or solid-phase extraction pretreatments. Serum aliquots (charcoal stripped fetal bovine serum, 100 μL) were spiked with four estrogen standards and their corresponding isotope-labeled internal standards, then bulk derivatized with 2-fluoro-1-methyl-pyridium p-toluenesulfonate (2-FMP) to establish the calibration curves and perform method validation. Calibration was established in the concentration ranges of 5–1000 pg mL{sup −1}, and demonstrated good linearity of R{sup 2} from 0.9944 to 0.9997 for the four derivatized estrogens. The lower detection limits obtained were 3–7 pg mL{sup −1}. Good accuracy and precision in the range of 86–112% and 2.3–11.9%, respectively, were observed for the quality control (QC) samples at low, medium, and high concentration levels. The stability tests showed that the derivatized serum samples were stable 8 h after derivatization at room temperature and at least to 48 h if stored at −20 °C. The method was applied to measure trace estrogens in real human and bovine serum samples, and three of four estrogen compounds studied were observed and quantified.

  20. Simultaneous speciation neutron activation analysis for trace elements

    International Nuclear Information System (INIS)

    Chatt, A.; Kiceniuk, J.W.; Menendez Sanchez, W.; Bottaro, C.

    2006-01-01

    Among the various forms of neutron activation technique being developed in our laboratory, much emphasis has been placed over the last ten years or so on the development of simultaneous speciation neutron activation analysis (SSNAA). This technique can now be used for the simultaneous determination of various species of a number of elements. Almost all speciation techniques consist of two steps. The first step involves the separation of species from the sample followed by the second step of element-specific detection. A number of characteristic features of NAA, which other techniques normally do not possess, can be advantageously exploited in SSNAA. For example, SSNAA can be used for: (i) multielement speciation with high specificity, (ii) speciation of chemically dissimilar elements such as Cd, Mn and Se, (iii) speciation of elements such as Cl, Br and I which are rather difficult to determine by most other techniques, etc. We have developed SSNAA methods for assaying various arsenic species, namely As(III), As(V), dimethyl arsonic acid (DMA), monomethylarsinic acid (MMA), arsenobetaine (AsB), organically bound arsenic (OBAs), and lipid-soluble arsenic (LSAs) in marine fish samples. We have extended these methods to include simultaneous determination of various species of As, Sb and Se in water. We have also developed SSNAA methods employing biochemical techniques for the simultaneous separation, preconcentration and characterization of metalloproteins and protein-bound trace element species of As, Br, Cd, Cu, Mn, Se, and Zn. We have developed methods for the simultaneous separation and characterization of organohalogen compounds in fish. An overview of the SSNAA methods being developed in our laboratory will be presented. (author)

  1. NICKEL SPECIATION OF URBAN PARTICULATE MATTER

    Energy Technology Data Exchange (ETDEWEB)

    Kevin C. Galbreath; Charlene R. Crocker; Carolyn M. Nyberg; Frank E. Huggins; Gerald P. Huffman

    2003-10-01

    A four-step sequential Ni extraction method, summarized in Table AB-1, was evaluated for identifying and quantifying the Ni species occurring in urban total suspended particulate (TSP) matter and fine particulate matter (<10 {micro}m [PM{sub 10}] and <2.5 {micro}m [PM{sub 2.5}] in aerodynamic diameter). The extraction method was originally developed for quantifying soluble, sulfidic, elemental, and oxidic forms of Ni that may occur in industrial atmospheres. X-ray diffraction (XRD) and x-ray absorption fine structure (XAFS) spectroscopy were used to evaluate the Ni species selectivity of the extraction method. Uncertainties in the chemical speciation of Ni in urban PM{sub 10} and PM{sub 2.5} greatly affect inhalation health risk estimates, primarily because of the large variability in acute, chronic, and cancer-causing effects for different Ni compounds.

  2. The speciation of dissolved elements in aquatic solution. Radium and actinides

    International Nuclear Information System (INIS)

    Haesaenen, E.

    1994-01-01

    In the publication, the chemistry and speciation of radium, thorium, protactinium, uranium, neptunium, lutonium, americium and curium in ground-water environment is reviewed. Special attention is given to the transuranium elements, which have a central role in the repository of nuclear wastes. The most important methods used in the speciation of these elements is presented. The laser-induced methods, developed in the 1980's, are especially discussed. These have made it possible, e.g., to speciate the transuranium elements in their very low, actual repository ground-water concentrations (10-100 ng/l). (54 refs., 10 figs., 3 tabs.)

  3. Aspects of speciation in foodstuffs

    International Nuclear Information System (INIS)

    Crews, Helen M.

    2001-01-01

    Food is the primary source of trace elements for humans and it is now generally accepted that the bioavailability of a given element and its behaviour in the body depends upon its chemical form. This point was illustrated with the example of arsenic speciation in fish in which bioaccumulation takes place in the marine food chain, however, the species of arsenic ingested by man when the fish is consumed are not toxic. It was pointed out that species information will be vital in deciding upon realistic average dietary requirements for trace elements, particularly because both deficiency or excess of an element can have detrimental consequences on an individual's health. Two examples of speciation studies with food (Cd and Se) were presented and the importance of the use of label technology which will allow studies of target analytes at physiological levels, was stressed

  4. Solid phase microextraction method using a novel polystyrene oleic acid imidazole polymer in micropipette tip of syringe system for speciation and determination of antimony in environmental and food samples.

    Science.gov (United States)

    Panhwar, Abdul Haleem; Tuzen, Mustafa; Hazer, Baki; Kazi, Tasneem Gul

    2018-07-01

    A simple, rapid and sensitive solid phase microextraction method was used for the speciation of inorganic antimony (Sb) by using a novel synthesized polymeric material in micropipette tip of syringe system. In present methodology, the specie of Sb (III) made hydrophobic complex with diethyl dithiocarbamate (DDTC) at pH 5.5 and subsequently adsorbed on polystyrene oleic acid imidazole polymer (POIP), whereas Sb(V) did not made complex and adsorbed on the polymer, remained in aqueous solutions. The strategy of multivariate was carried out to screen out the different variables and assessed the optimum values of their experimental values for the extraction efficiency of analyte. Then the analyte was sorbed on the polymer in micropipette tip of syringe system was quantitatively eluted by different types of acids at different levels for 2-6 aspirating/dispensing cycles. The extracted Sb(III) ions with modifiers were directed into the graphite furnace atomic absorption spectrometry for analysis. The limit of detection (LOD), limit of quantification (LOQ) and preconcentration factor (PF) for Sb(III) was found to be 6 ng L -1 , 20 ng L -1 and 100. The RSD value was found to be 4.2%. The standard addition method and certified reference materials were checked for accuracy and validity of method. The developed method was effectively applied for the determination of total and inorganic species of Sb(III) and Sb(V) in different types of water samples, whereas only total Sb was determined in acid digested soil, Tuna fish, rice, spinach, black tea, mixed fruit juice and ice tea samples. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. Optimization of an anion-exchange high performance liquid chromatography-inductively coupled plasma-mass spectrometric method for the speciation analysis of oxyanion-forming metals and metalloids in leachates from cement-based materials.

    Science.gov (United States)

    Mulugeta, Mesay; Wibetoe, Grethe; Engelsen, Christian J; Lund, Walter

    2010-10-01

    A method was developed for the speciation analysis of the oxyanions of As(III), As(V), Cr(VI), Mo(VI), Sb(III), Sb(V), Se(IV), Se(VI) and V(V) in leachates from cement-based materials, based on anion-exchange HPLC coupled with ICP-MS. The method was optimized in a two-step multivariate approach: the effect of sample pH and mobile phase composition on resolution, peak symmetry and analysis time was studied. Optimum conditions were then identified for the significant experimental factors by studying their interdependence. A mobile phase composition of 20 mM ammonium nitrate, 50 mM ammonium tartrate and pH 9.5 was found to be a compromise optimum for the separation of the target analytes using isocratic elution. The optimum condition provided separation of the analytes in less than 6 min, at a mobile phase flow rate of 1.0 mL/min. The signal intensities of the analytes were improved by adding 1% methanol to the mobile phase. The limit of detection of the method was in the range 0.2-2.2 μg/L for the various species. The effect of sample constituents was studied using spiked concrete leachates. The method was used to determine the target oxyanionic species in leachates generated from a concrete material in the pH range 3.5-12.4; CrO(4)(2-), MoO(4)(2-) and VO(4)(3-) were detected in most of the leachates. Copyright © 2010 Elsevier B.V. All rights reserved.

  6. An experimental design approach for optimization of spectrophotometric method for estimation of cefixime trihydrate using ninhydrin as derivatizing reagent in bulk and pharmaceutical formulation

    Directory of Open Access Journals (Sweden)

    Yogita B. Wani

    2017-01-01

    Full Text Available The aim of the present work is to use experimental design to screen and optimize experimental variables for developing a spectrophotometric method for determining cefixime trihydrate content using ninhydrin as a derivatizing reagent. The method is based on the reaction of the amino group of cefixime with ninhydrin in an alkaline medium to form a yellow-colored derivative (λmax 436 nm. A two-level full factorial design was utilized to screen the effect of ninhydrin reagent concentration (X1, volume of ninhydrin reagent (X2, heating temperature (X3 and heating time (X4 on the formation of the cefixime–ninhydrin complex Y (absorbance. One way ANOVA and Pareto ranking analyses have shown that the ninhydrin reagent concentration (X1, volume of ninhydrin reagent (X2 and heating temperature (X3 were statistically significant factors (P < 0.05 affecting the formation of the cefixime–ninhydrin complex Y (absorbance. A Box-Behnken experimental design with response surface methodology was then utilized to evaluate the main, interaction and quadratic effects of these three factors on the selected response. With the help of a response surface plot and contour plot the optimum values of the selected factors were determined and used for further experiments. These values were a ninhydrin reagent concentration (X1 of 0.2% w/v, volume of ninhydrin reagent (X2 of 1 mL and heating temperature (X3 of 80 °C. The proposed method was validated according to the ICH Q2 (R1 method validation guidelines. The results of the present study have clearly shown that an experimental design concept may be effectively applied to the optimization of a spectrophotometric method for estimating the cefixime trihydrate content in bulk and pharmaceutical formulation with the least number of experimental runs possible.

  7. Bulk metallic glass matrix composites

    International Nuclear Information System (INIS)

    Choi-Yim, H.; Johnson, W.L.

    1997-01-01

    Composites with a bulk metallic glass matrix were synthesized and characterized. This was made possible by the recent development of bulk metallic glasses that exhibit high resistance to crystallization in the undercooled liquid state. In this letter, experimental methods for processing metallic glass composites are introduced. Three different bulk metallic glass forming alloys were used as the matrix materials. Both ceramics and metals were introduced as reinforcement into the metallic glass. The metallic glass matrix remained amorphous after adding up to a 30 vol% fraction of particles or short wires. X-ray diffraction patterns of the composites show only peaks from the second phase particles superimposed on the broad diffuse maxima from the amorphous phase. Optical micrographs reveal uniformly distributed particles in the matrix. The glass transition of the amorphous matrix and the crystallization behavior of the composites were studied by calorimetric methods. copyright 1997 American Institute of Physics

  8. MODELING MONOMETHYLMERCURY AND TRIBUTYLTIN SPECIATION WITH EPA'S GEOCHEMICAL SPECIATION MODEL MINTEQA2

    Science.gov (United States)

    Given the complexity of the various, simultaneous (and competing) equilibrium reactions governing the speciation of ionic species in aquatic systems, EPA has developed and distributed the geochemical speciation model MINTEQA2 (Brown and Allison, 1987, Allison et al., 1991; Hydrog...

  9. Development of anion-exchange/reversed-phase high performance liquid chromatography-inductively coupled plasma-mass spectrometry methods for the speciation of bio-available iodine and bromine from edible seaweed.

    Science.gov (United States)

    Romarís-Hortas, Vanessa; Bermejo-Barrera, Pilar; Moreda-Piñeiro, Antonio

    2012-05-04

    Anion exchange high performance liquid chromatography hyphenated with inductively coupled plasma-mass spectrometry has been novelly applied to assess inorganic (iodide and iodate) and organic (3-iodotyrosine - MIT, and 3,5-diiodotyrosine - DIT) iodine species in a single chromatographic run. The optimized operating conditions (Dionex IonPac AS7, gradient elution with 175 mM ammonium nitrate plus 15% (v/v) methanol, pH 3.8, as a mobile phase and flow rates within the 0.5-1.5 mL min(-1) range) have also been used to perform inorganic bromine speciation analysis (bromide and bromate). The developed method has been applied for determining the bio-available contents of iodine and bromine species in dialyzates from edible seaweed. Reverse phase high performance liquid chromatography (Zorbax Eclipse XDB-C8, gradient elution with 0.2% (m/m) acetic acid, and 0.2% (m/m) acetic acid in methanol, as mobile phases, and a constant flow rate of 0.75 mL min(-1)) also hyphenated with inductively coupled plasma-mass spectrometry was used to confirm the presence of organic iodine species (MIT and DIT) in the dialyzates. The verification of the presence of iodinated amino acids (MIT and DIT) in the extracts was also performed by reverse phase high performance liquid chromatography-electrospray ionization-mass spectrometry (LTQ Orbitrap). The developed methods have provided good repeatability (RSD values lower than 10% for both anion exchange and reverse phase separations) and analytical recoveries within the 90-105% range for all cases. The in vitro bio-availability method consisted of a simulated gastric and an intestinal digestion/dialysis (10 kDa molecular weight cut-off - MWCO) two-stage procedure. Iodide and MIT were the main bio-available species quantified, whereas bromide was the major bromine species found in the extracts. Copyright © 2012 Elsevier B.V. All rights reserved.

  10. Purex process modelling - do we really need speciation data?

    International Nuclear Information System (INIS)

    Taylor, R.J.; May, I.

    2001-01-01

    The design of reprocessing flowsheets has become a complex process requiring sophisticated simulation models, containing both chemical and engineering features. Probably the most basic chemical data needed is the distribution of process species between solvent and aqueous phases at equilibrium, which is described by mathematical algorithms. These algorithms have been constructed from experimentally determined distribution coefficients over a wide range of conditions. Distribution algorithms can either be empirical fits of the data or semi-empirical equations, which describe extraction as functions of process variables such as temperature, activity coefficients, uranium loading, etc. Speciation data is not strictly needed in the accumulation of distribution coefficients, which are simple ratios of analyte concentration in the solvent phase to that in the aqueous phase. However, as we construct process models of increasing complexity, speciation data becomes much more important both to raise confidence in the model and to understand the process chemistry at a more fundamental level. UV/vis/NIR spectrophotometry has been our most commonly used speciation method since it is a well-established method for the analysis of actinide ion oxidation states in solution at typical process concentrations. However, with the increasing availability to actinide science of more sophisticated techniques (e.g. NMR; EXAFS) complementary structural information can often be obtained. This paper will, through examples, show how we have used spectrophotometry as a primary tool in distribution and kinetic experiments to obtain data for process models, which are then validated through counter-current flowsheet trials. It will also discuss how spectrophotometry and other speciation methods are allowing us to study the link between molecular structure and extraction behaviour, showing how speciation data really is important in PUREX process modelling. (authors)

  11. Effects of graphite doping on critical current density and microstructure of MgB2 bulks by an improved Mg-diffusion method

    International Nuclear Information System (INIS)

    Pan, X.F.; Zhao, Y.; Feng, Y.; Yang, Y.; Cheng, C.H.

    2008-01-01

    abstract: A series of graphite-doped MgB 2 bulks with high density have been successfully prepared by an improved Mg-diffusion method in ambient pressure. The effects of graphite doping on lattice parameters, T c , J c and microstructure of MgB 2 have been investigated. The results show that compared to the nano-C-doped or CNTs-doped MgB 2 , C is not easy to substitute B in graphite-doped MgB 2 . However, at the same C content, the graphite-doped MgB 2 has a higher J c . At 10 K and self-field, the J c for MgB 1.985 C 0.015 reaches 0.58 MA/cm 2 . For the MgB 1.945 C 0.055 , at 5 K, 7 T and 10 K, 6 T the J c achieves 10,000 A/cm 2 which is two orders of magnitude higher than that for the undoped sample. In addition to improving electron scattering and intergranular connectivity, the unreacted graphite in the graphite-doped MgB 2 is proposed to be responsible to the excellent J c properties of MgB 2 in high fields, due to depressed grain growth and enhanced grain boundary flux pinning

  12. The chemical speciation and analysis of trace elements in sediment with Neutron Activation Analytical method(NAA) and atomic mass spectrometry

    International Nuclear Information System (INIS)

    Nam, Sang-Ho; Kim, Jae-Jin; Chung, Yong-Sam; Kim, Sun-Ha

    2003-01-01

    In this research, first of all, the analytical methods for the determination of major elements in sediment have been developed with ICP-MS (Inductively Coupled Plasma Mass Spectrometry). The analytical results of major elements (Al, Ca, K, Fe, Mg) with Cool ICP-MS were much better than those with normal ICP-MS. The analytical results were compared with those of NAA (Neutron Activation Analysis). NAA were a little superior to ICP-MS for the determination of major elements in sediment as a non-destructive trace analytical trace analytical method. The analytical methods for the determination of minor elements (Cr, Ce, U, Co, Pb, As, Se) have been also developed with ICP-MS. The analytical results by standard calibration curve with ICP-MS were not accurate due to the matrix interferences. Thus, the internal standard method was applied, then the analytical results for minor elements with ICP-MS were greatly improved. The analytical results obtained by ICP-MS were compared with those obtained by NAA. It showed that the two analytical methods have great capabilities for the determination of minor elements in sediments. Accordingly, the NAA will plan an important role in analysis of environment sample with complex matrix. ICP-MS also will play an important role because it has a great capability for the determination of Pb that could not be determined by NAA

  13. Speciation and solubility of neptunium in underground environments by paper electrophoresis

    International Nuclear Information System (INIS)

    Nagasaki, S.; Tanaka, Satoru; Takahashi, Yoichi

    1988-01-01

    Speciation and solubility of neptunium were studied using paper electrophoresis, ion exchange and ultrafiltration. Among these methods, the paper electrophoresis was found to be suitable for measuring speciation and solubility of neptunium of low concentration, if chemical species had opposite charge to each other or dissolved species had a charge. Using paper electrophoresis, hydrolysis constants of NpO 2 OH 0 and NpO 2 - (OH) 2 - and solubility product of NpO 2 were obtained and ionic-strength dependence of speciation was observed. (author) 9 refs.; 3 figs.; 2 tabs

  14. Uranium speciation in Fernald soils

    International Nuclear Information System (INIS)

    Morris, D.E.; Conradson, S.D.; Tait, C.D.; Chisholm-Brause, C.J.; Berg, J.; Musgrave, J.

    1992-01-01

    This report details progress made from January 1 to May 31, 1992 in this analytical support task to determine the speciation of uranium in contaminated soil samples from the Fernald Environmental Management Project site under the auspices of the Uranium in Soils Integrated Demonstration funded through the US DOE's Office of Technology Development. The authors' efforts have focused on characterization of soil samples collected by S.Y. Lee (Oak Ridge National Laboratory) from five locales at the Fernald site. These were chosen to sample a broad range of uranium source terms. On the basis of x-ray absorption spectroscopy data, they have determined that the majority of uranium (> 80--90%) exists in the hexavalent oxidation state for all samples examined. This is a beneficial finding from the perspective of remediation, because U(VI) species are more soluble in general than uranium species in other oxidation states. Optical luminescence data from many of the samples show the characteristic structured yellow-green emission from the uranyl (UO 2 2+ ) moiety. The luminescence data also suggest that much of the uranium in these soils is present as well-crystallized UO 2 2+ species. Some clear spectroscopic distinctions have been noted for several samples that illustrate significant differences in the speciation (1) from site to site, (2) within different horizons at the same site, and (3) within different size fractions of the soils in the same horizon at the same site. This marked heterogeneity in uranyl speciation suggests that several soil washing strategies may be necessary to reduce the total uranium concentrations within these soils to regulatory limits

  15. Ion-pair chromatography coupled to inductively coupled plasma-mass spectrometry (IPC-ICP-MS) as a method for thiomolybdate speciation in natural waters.

    Science.gov (United States)

    Lohmayer, Regina; Reithmaier, Gloria Maria Susanne; Bura-Nakić, Elvira; Planer-Friedrich, Britta

    2015-03-17

    Molybdenum precipitates preferentially under reducing conditions; therefore, its occurrence in sediment records is used as an indicator of paleoredox conditions. Although thiomolybdates (MoO4-xSx(2-) with x = 1-4) supposedly are necessary intermediates in the process of molybdenum precipitation under anoxic conditions, there is no information about their abundance in natural environments, because of a lack of element-specific methods with sufficiently low detection limits. Here, we optimized ion-pair chromatographic separation for coupling to an inductively coupled plasma-mass spectrometry detector (IPC-ICP-MS). 2-Propanol (10%-25% gradient) replaced the previously used acetonitrile (25%-75%) as the solvent, to reduce the carbon load into the plasma. In synthetic solutions, formation of thiomolybdates was found to occur spontaneously in the presence of excess sulfide and the degree of thiolation was highest at pH 7. Excess hydroxyl led to a transformation of thiomolybdates to molybdate. Under acidic to neutral conditions, precipitation of molybdenum and hydrolysis of tetrathiomolybdate were observed. Flash-freezing was found to be suitable to stabilize tetrathiomolybdate, with 2 mM) negatively affected the detection of molybdate, which eluted mainly in the dead volume, but had no negative effect on higher thiolated molybdates. Detection limits were ∼10 nM. With the newly developed IPC-ICP-MS method, thiomolybdates were found to form spontaneously in euxinic marine waters after adding a molybdate spike and occur naturally in sulfidic geothermal waters.

  16. Speciation of Pb in industrially polluted soils

    DEFF Research Database (Denmark)

    Jensen, Pernille Erland; Ottosen, Lisbeth M.; Pedersen, Anne Juul

    2006-01-01

    This study was aimed at elucidating the importance of original Pb-speciation versus soil-characteristics to mobility and distribution of Pb in industrially polluted soils. Ten industrially polluted Danish surface soils were characterized and Pb speciation was evaluated through SEM-EDX studies...

  17. Contribution of neutron activation analysis and radioanalytical techniques to trace element speciation in environmental analysis

    International Nuclear Information System (INIS)

    Gallorini, M.; Orvini, E.; Sabbioni, E.; Pietra, R.

    1984-01-01

    The feasibility of the NAA in contributing to trace element speciation in environmental and biological samples is shown by a few selected applications. They are: (i) the determination of different species of vanadium, arsenic and selenium in freshwater. The pre-irradiation treatments in which the different chemical species are selectively isolated are critically evaluated. Problems arising from possible contaminations or losses and from blanks are discussed; (ii) the use of NAA in metallobiochemical speciation once biochemical methods of cellular fractionation for the isolation of metallobiocomplexes are developed. Examples concern the biochemical speciation of vanadium in human blood and the development of a method for speciation of inorganic and organic arsenic compounds in biological samples. The use of radioanalytical techniques in developing the separation procedures of different trace metal chemical and biochemical species is also briefly discussed. 24 references, 5 figures, 4 tables

  18. Effects of graphite doping on critical current density and microstructure of MgB{sub 2} bulks by an improved Mg-diffusion method

    Energy Technology Data Exchange (ETDEWEB)

    Pan, X.F. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Zhao, Y. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia)], E-mail: yshao@home.swjtu.edu.cn; Feng, Y. [Northwest Institute for Nonferrous Metal Research, P.O. Box 51, Xi' an, Shaanxi 710016 (China); Western Superconductivity Technology Company, Xi' an (China); Yang, Y. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); Cheng, C.H. [Key Laboratory of Magnetic Levitation and Maglev Trains (Ministry of Education of China), Superconductivity R and D Center (SRDC), Mail Stop 165, Southwest Jiaotong University, Chengdu, Sichuan 610031 (China); School of Materials Science and Engineering, University of New South Wales, Sydney 2052, NSW (Australia)

    2008-09-15

    abstract: A series of graphite-doped MgB{sub 2} bulks with high density have been successfully prepared by an improved Mg-diffusion method in ambient pressure. The effects of graphite doping on lattice parameters, T{sub c}, J{sub c} and microstructure of MgB{sub 2} have been investigated. The results show that compared to the nano-C-doped or CNTs-doped MgB{sub 2}, C is not easy to substitute B in graphite-doped MgB{sub 2}. However, at the same C content, the graphite-doped MgB{sub 2} has a higher J{sub c}. At 10 K and self-field, the J{sub c} for MgB{sub 1.985}C{sub 0.015} reaches 0.58 MA/cm{sup 2}. For the MgB{sub 1.945}C{sub 0.055}, at 5 K, 7 T and 10 K, 6 T the J{sub c} achieves 10,000 A/cm{sup 2} which is two orders of magnitude higher than that for the undoped sample. In addition to improving electron scattering and intergranular connectivity, the unreacted graphite in the graphite-doped MgB{sub 2} is proposed to be responsible to the excellent J{sub c} properties of MgB{sub 2} in high fields, due to depressed grain growth and enhanced grain boundary flux pinning.

  19. Advances in Ecological Speciation: an integrative approach.

    Science.gov (United States)

    Faria, Rui; Renaut, Sebastien; Galindo, Juan; Pinho, Catarina; Melo-Ferreira, José; Melo, Martim; Jones, Felicity; Salzburger, Walter; Schluter, Dolph; Butlin, Roger

    2014-02-01

    The role of natural selection in promoting reproductive isolation has received substantial renewed interest within the last two decades. As a consequence, the study of ecological speciation has become an extremely productive research area in modern evolutionary biology. Recent innovations in sequencing technologies offer an unprecedented opportunity to study the mechanisms involved in ecological speciation. Genome scans provide significant insights but have some important limitations; efforts are needed to integrate them with other approaches to make full use of the sequencing data deluge. An international conference 'Advances in Ecological Speciation' organized by the University of Porto (Portugal) aimed to review current progress in ecological speciation. Using some of the examples presented at the conference, we highlight the benefits of integrating ecological and genomic data and discuss different mechanisms of parallel evolution. Finally, future avenues of research are suggested to advance our knowledge concerning the role of natural selection in the establishment of reproductive isolation during ecological speciation. © 2013 John Wiley & Sons Ltd.

  20. Speciation of actinides in marine waters

    International Nuclear Information System (INIS)

    Roberts, R.A.

    1984-01-01

    The oxidation state distribution of plutonium in seawater, pore water from marine sediments, and a series of model solutions similar to seawater was measured using a TTA solvent extraction technique and α liquid scintillation counting methods. Electromigration was used to compare migration behavior of americium in 0.7M NaCl solutions (pH 6.5 to 8.0) with the behavior calculated from predicted speciation. In all pH 8 solutions studied, Pu(VI) was rapidly reduced to Pu(V). In 0.7M NaCl, pH 8.0, and artifical seawater (no organics), the Pu(V) formed was stable. In real seawater (with organic components), a rapid reduction of Pu(VI) to Pu(IV) was also observed. The Pu(V) formed in seawater was metastable; a very slow reduction to Pu(IV) occurred. This reduction was catalyzed by light. Humic acid (obtained from marine sediments from the Bahama Islands), was added to 0.7M NaCl, pH 8.0 solutions to determine its effect on Pu redox reactions. The effect was similar to the reductions in seawater. Increasing the humic acid concentration decreased the amount of Pu(V) which was formed and favored the IV state. The americium electromigration experiments showed a +0.12 net charge for the Am complexes formed in 0.7M NaCl solutions from pH 7.0 to 8.0. This value was smaller than the charge of +0.94 calculated from predicted speciation

  1. Large area bulk superconductors

    Science.gov (United States)

    Miller, Dean J.; Field, Michael B.

    2002-01-01

    A bulk superconductor having a thickness of not less than about 100 microns is carried by a polycrystalline textured substrate having misorientation angles at the surface thereof not greater than about 15.degree.; the bulk superconductor may have a thickness of not less than about 100 microns and a surface area of not less than about 50 cm.sup.2. The textured substrate may have a thickness not less than about 10 microns and misorientation angles at the surface thereof not greater than about 15.degree.. Also disclosed is a process of manufacturing the bulk superconductor and the polycrystalline biaxially textured substrate material.

  2. Microfabricated Bulk Piezoelectric Transformers

    Science.gov (United States)

    Barham, Oliver M.

    Piezoelectric voltage transformers (PTs) can be used to transform an input voltage into a different, required output voltage needed in electronic and electro- mechanical systems, among other varied uses. On the macro scale, they have been commercialized in electronics powering consumer laptop liquid crystal displays, and compete with an older, more prevalent technology, inductive electromagnetic volt- age transformers (EMTs). The present work investigates PTs on smaller size scales that are currently in the academic research sphere, with an eye towards applications including micro-robotics and other small-scale electronic and electromechanical sys- tems. PTs and EMTs are compared on the basis of power and energy density, with PTs trending towards higher values of power and energy density, comparatively, indicating their suitability for small-scale systems. Among PT topologies, bulk disc-type PTs, operating in their fundamental radial extension mode, and free-free beam PTs, operating in their fundamental length extensional mode, are good can- didates for microfabrication and are considered here. Analytical modeling based on the Extended Hamilton Method is used to predict device performance and integrate mechanical tethering as a boundary condition. This model differs from previous PT models in that the electric enthalpy is used to derive constituent equations of motion with Hamilton's Method, and therefore this approach is also more generally applica- ble to other piezoelectric systems outside of the present work. Prototype devices are microfabricated using a two mask process consisting of traditional photolithography combined with micropowder blasting, and are tested with various output electri- cal loads. 4mm diameter tethered disc PTs on the order of .002cm. 3 , two orders smaller than the bulk PT literature, had the followingperformance: a prototype with electrode area ratio (input area / output area) = 1 had peak gain of 2.3 (+/- 0.1), efficiency of 33 (+/- 0

  3. US EPA's SPECIATE 4.4 Database: Development and Uses

    Science.gov (United States)

    SPECIATE is the U.S. Environmental Protection Agency’s (EPA) repository of volatile organic gas and particulate matter (PM) speciation profiles of air pollution sources. EPA released SPECIATE 4.4 in early 2014 and, in total, the SPECIATE 4.4 database includes 5,728 PM, volatile o...

  4. Trace and ultratrace level elemental and speciation analysis

    International Nuclear Information System (INIS)

    Arunachalam, J.

    2012-01-01

    Accurate determination of elements present at parts per million and billion levels in various matrices is a growing requirement in different fields. In environmental sciences various trace elements need to be analyzed so as establish the dispersal models of pollutants or the adequacy of effluent treatment prior to discharge into water bodies. The issues of bioaccumulation and magnification are important in aquatic systems. In nutrition and biochemistry one has to establish the bio-availability of essential and toxic elemental species as toxic elements prevent assimilation of essential elements. Fission and fusion technologies use a variety of structural materials requiring many trace elements to be present at levels strictly below the specified levels. Ultra-pure bulk semiconductor materials are required for fabrication devices. In metallurgy and materials sciences too, various trace elements are known to influence the properties. In the emerging fields like nanotechnology, it is necessary to understand the passage and accumulation of nano-particles inside the cells, through trace analysis. Many analytical techniques exist which can provide the concentration information in the bulk materials with good accuracy. They include ICP-AES, FAAS, and ICP-MS, which are solution based techniques. Direct solid state analytical techniques are Glow Discharge Mass Spectrometry (GDMS) and XRF. Accelerator based ion-beam analysis techniques can provide information on concentration and depth profiles of different elements in layered structures. Hyphenated techniques such as HPLC/lC-ICPMS, are helpful in identifying various chemical oxidation states in which a given element might be present in a matrix, which is termed as speciation analysis. This presentation will include the existing analytical competencies and the laboratory requirements for trace and ultra trace element elemental and speciation analyses and their applications. (author)

  5. Trace metal characterization and speciation in geothermal effluent by multiple scanning anodic stripping voltammetry and atomic absorption analysis

    Energy Technology Data Exchange (ETDEWEB)

    Kowalski, B.R.

    1979-05-25

    Recent studies have shown geothermal power plants to have a significant environmental impact on the ground water of the area. The heavy metals arsenic and mercury are special problems, as both are concentrated by flora and fauna exposed to the effluent waters. Because the toxicity of these and other metallic pollutants present in geothermal effluent depends on the chemical form, or speciation, of the particular metal, any serious study of the environmental impact of a geothermal development should include studies of trace metal speciation, in addition to trace metal concentration. This proposal details a method for determining metal speciation in dilute waters. The method is based on ion-exchange and backed by atomic absorption spectrometry and multiple scanning anodic stripping voltammetry. Special laboratory studies will be performed on mercury, arsenic and selenium speciation in synthetic geothermal water. The method will be applied to three known geothermal areas in Washington and Oregon, with emphasis on the speciation of mercury, arsenic and selenium in these waters. The computer controlled electrochemical instrumentation was built and tested. Using this instrumentation, a new experimental procedure was developed to determine the chemical form (speciation) of metal ions in very dilute solutions (ng/ml). This method was tested on model systems including Pb, Cd, and As with C1/sup -/, CO/sub 3//sup 2 -/ and glycine ligands. Finally, the speciation of lead in a geothermal water was examined and the PbC1/sup +/ complex was observed and quantified.

  6. Pb speciation results in amended soils

    Data.gov (United States)

    U.S. Environmental Protection Agency — The dataset shows the distribution of Pb phases resulting from various amendments to change Pb speciation. This dataset is associated with the following publication:...

  7. Evolution: sympatric speciation the eusocial way

    DEFF Research Database (Denmark)

    Boomsma, Jacobus Jan; Nash, David Richard

    2014-01-01

    Sympatric speciation normally requires particular conditions of ecological niche differentiation. However, ant social parasites have been suspected to arise sympatrically, because (dis)loyalty to eusocial kin-structures induces disruptive selection for dispersal and inbreeding. A new study docume...

  8. Dearborn GC-MS organic speciation data

    Data.gov (United States)

    U.S. Environmental Protection Agency — Ambient particulate matter organic speciation data from July - August, 2011. This dataset is associated with the following publication: Lynam, M., T. Dvonch, J....

  9. Aerosol Chemical Speciation Monitor (ACSM) Instrument Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Watson, Thomas B. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2017-08-15

    The Aerodyne Aerosol Chemical Speciation Monitor (ACSM) measures particle mass loading and chemical composition in real time for non-refractory sub-micron aerosol particles. The ACSM is designed for long-term unattended deployment and routine monitoring applications.

  10. Coulombic Fluids Bulk and Interfaces

    CERN Document Server

    Freyland, Werner

    2011-01-01

    Ionic liquids have attracted considerable interest in recent years. In this book the bulk and interfacial physico-chemical characteristics of various fluid systems dominated by Coulomb interactions are treated which includes molten salts, ionic liquids as well as metal-molten salt mixtures and expanded fluid metals. Of particular interest is the comparison of the different systems. Topics in the bulk phase concern the microscopic structure, the phase behaviour and critical phenomena, and the metal-nonmetal transition. Interfacial phenomena include wetting transitions, electrowetting, surface freezing, and the electrified ionic liquid/ electrode interface. With regard to the latter 2D and 3D electrochemical phase formation of metals and semi-conductors on the nanometer scale is described for a number of selected examples. The basic concepts and various experimental methods are introduced making the book suitable for both graduate students and researchers interested in Coulombic fluids.

  11. Research on the chemical speciation of actinides

    International Nuclear Information System (INIS)

    Jung, Euo Chang; Park, K. K.; Cho, H. R.

    2012-04-01

    A demand for the safe and effective management of spent nuclear fuel and radioactive waste generated from nuclear power plant draws increasing attention with the growth of nuclear power industry. The objective of this project is to establish the basis of research on the actinide chemistry by using highly sensitive and advanced laser-based spectroscopic systems. Researches on the chemical speciation of actinides are prerequisite for the development of technologies related to nuclear fuel cycles, especially, such as the safe management of high level radioactive wastes and the chemical examination of irradiated nuclear fuels. For supporting these technologies, laser-based spectroscopies have been applied for the chemical speciation of actinide in aqueous solutions and the quantitative analysis of actinide isotopes in spent nuclear fuels. In this report, results on the following subjects have been summarized. Development of TRLFS technology for the chemical speciation of actinides, Development of laser-induced photo-acoustic spectroscopy (LPAS) system, Application of LIBD technology to investigate dynamic behaviors of actinides dissolution reactions, Development of nanoparticle analysis technology in groundwater using LIBD, Chemical speciation of plutonium complexes by using a LWCC system, Development of LIBS technology for the quantitative analysis of actinides, Evaluation on the chemical reactions between actinides and humic substances, Spectroscopic speciation of uranium-ligand complexes in aqueous solution, Chemical speciation of actinides adsorbed on metal oxides surfaces

  12. Research on the chemical speciation of actinides

    International Nuclear Information System (INIS)

    Jung, Euo Chang; Park, K. K.; Cho, H. R.

    2010-04-01

    A demand for the safe and effective management of spent nuclear fuel and radioactive waste generated from nuclear power plant draws increasing attention with the growth of nuclear power industry. The objective of this project is to establish the basis of research on the actinide chemistry by using advanced laser-based highly sensitive spectroscopic systems. Researches on the chemical speciation of actinides are prerequisite for the development of technologies related to nuclear fuel cycles, especially, such as the safe management of high level radioactive wastes and the chemical examination of irradiated nuclear fuels. For supporting these technologies, laser-based spectroscopies have been performed for the chemical speciation of actinide in an aqueous solutions and the quantitative analysis of actinide isotopes in spent nuclear fuels. In this report, results on the following subjects have been summarized. (1) Development of TRLFS technology for chemical speciation of actinides, (2) Development of LIBD technology for measuring solubility of actinides, (3) Chemical speciation of plutonium complexes by using a LWCC system, (4) Development of LIBS technology for the quantitative analysis of actinides, (5) Development of technology for the chemical speciation of actinides by CE, (6) Evaluation on the chemical reactions between actinides and humic substances, (7) Chemical speciation of actinides adsorbed on metal oxides surfaces, (8) Determination of actinide source terms of spent nuclear fuel

  13. Superductile bulk metallic glass

    International Nuclear Information System (INIS)

    Yao, K.F.; Ruan, F.; Yang, Y.Q.; Chen, N.

    2006-01-01

    Usually, monolithic bulk metallic glasses undergo inhomogeneous plastic deformation and exhibit poor ductility (<2%) at room temperature. We report a newly developed Pd-Si binary bulk metallic glass, which exhibits a uniform plastic deformation and a large plastic engineering strain of 82% and a plastic true strain of 170%, together with initial strain hardening, slight strain softening and final strain hardening characteristics. The uniform shear deformation and the ultrahigh plasticity are mainly attributed to strain hardening, which results from the nanoscale inhomogeneity due to liquid phase separation. The formed nanoscale inhomogeneity will hinder, deflect, and bifurcate the propagation of shear bands

  14. Solving mercury (Hg) speciation in soil samples by synchrotron X-ray microspectroscopic techniques

    International Nuclear Information System (INIS)

    Terzano, Roberto; Santoro, Anna; Spagnuolo, Matteo; Vekemans, Bart; Medici, Luca; Janssens, Koen; Goettlicher, Joerg; Denecke, Melissa A.; Mangold, Stefan; Ruggiero, Pacifico

    2010-01-01

    Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg -1 . Hg chemical forms were identified and quantified by sequential extractions and bulk- and micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as μ-XRF, μ-XRD and μ-XANES were necessary to solve bulk Hg speciation, in both soil fractions 3 S 2 Cl 2 ), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction <2 μm. No interaction among Hg-species and soil components was observed. All the observed Hg-species originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution. - Direct mercury (Hg) speciation in chlor-alkali plant contaminated soils enabled the identification of potentially dangerous Hg-S/Cl amorphous species.

  15. Speciation, in the nuclear fuel cycle by spectroscopic techniques

    International Nuclear Information System (INIS)

    Colette, S.; Plancque, G.; Allain, F.; Lamouroux, C.; Steiner, V.; Amekraz, B.; Moulin, C.

    2000-01-01

    New analytical techniques allowing to perform speciation in the framework of the nuclear fuel cycle are more and more needed. They have to be selective (since matrix encountered are very complex), sensitive (in order to work at representative concentration and below solubility limit), as well as non intrusive (in order to keep the image of the real solution). Among them, laser-based analytical techniques present these advantages together with the possibility to perform remote measurements via fiber optics. Hence, Time-Resolved Laser-Induced Fluorescence (TRLIF) has been used for actinides/lanthanides interaction and speciation studies in inorganic and organic matrices from the reprocessing to waste storage. Moreover, new ion detection methods such as Electro-Spray - Mass Spectrometry (ES-MS) seems promising for speciation studies. Hence, it is the first time that it is possible to directly couple a liquid at atmospheric pressure to a mass detection working at reduced pressure with a soft mode of ionisation that should allow to give informations on chemical species present. Principle, advantages and limitations as well as results obtained with the use of TRLIF and ES-MS on different systems of interest including actinides, lanthanides, fission products in interaction with simple organic molecules to very complex structure will be presented and discussed. (authors)

  16. Speciation, in the nuclear fuel cycle by spectroscopic techniques

    Energy Technology Data Exchange (ETDEWEB)

    Colette, S.; Plancque, G.; Allain, F.; Lamouroux, C.; Steiner, V.; Amekraz, B.; Moulin, C. [CEA/Saclay, Dept, des Procedes d' Enrichissement (DPE), 91 - Gif-sur-Yvette (France)

    2000-07-01

    New analytical techniques allowing to perform speciation in the framework of the nuclear fuel cycle are more and more needed. They have to be selective (since matrix encountered are very complex), sensitive (in order to work at representative concentration and below solubility limit), as well as non intrusive (in order to keep the image of the real solution). Among them, laser-based analytical techniques present these advantages together with the possibility to perform remote measurements via fiber optics. Hence, Time-Resolved Laser-Induced Fluorescence (TRLIF) has been used for actinides/lanthanides interaction and speciation studies in inorganic and organic matrices from the reprocessing to waste storage. Moreover, new ion detection methods such as Electro-Spray - Mass Spectrometry (ES-MS) seems promising for speciation studies. Hence, it is the first time that it is possible to directly couple a liquid at atmospheric pressure to a mass detection working at reduced pressure with a soft mode of ionisation that should allow to give informations on chemical species present. Principle, advantages and limitations as well as results obtained with the use of TRLIF and ES-MS on different systems of interest including actinides, lanthanides, fission products in interaction with simple organic molecules to very complex structure will be presented and discussed. (authors)

  17. Auctioning Bulk Mobile Messages

    NARCIS (Netherlands)

    S. Meij (Simon); L-F. Pau (Louis-François); H.W.G.M. van Heck (Eric)

    2003-01-01

    textabstractThe search for enablers of continued growth of SMS traffic, as well as the take-off of the more diversified MMS message contents, open up for enterprises the potential of bulk use of mobile messaging , instead of essentially one-by-one use. In parallel, such enterprises or value added

  18. Diffusion or bulk flow

    DEFF Research Database (Denmark)

    Schulz, Alexander

    2015-01-01

    is currently matter of discussion, called passive symplasmic loading. Based on the limited material available, this review compares the different loading modes and suggests that diffusion is the driving force in apoplasmic loaders, while bulk flow plays an increasing role in plants having a continuous...

  19. Ferromagnetic bulk glassy alloys

    International Nuclear Information System (INIS)

    Inoue, Akihisa; Makino, Akihiro; Mizushima, Takao

    2000-01-01

    This paper deals with the review on the formation, thermal stability and magnetic properties of the Fe-based bulk glassy alloys in as-cast bulk and melt-spun ribbon forms. A large supercooled liquid region over 50 K before crystallization was obtained in Fe-(Al, Ga)-(P, C, B, Si), Fe-(Cr, Mo, Nb)-(Al, Ga)-(P, C, B) and (Fe, Co, Ni)-Zr-M-B (M=Ti, Hf, V, Nb, Ta, Cr, Mo and W) systems and bulk glassy alloys were produced in a thickness range below 2 mm for the Fe-(Al, Ga)-(P, C, B, Si) system and 6 mm for the Fe-Co-(Zr, Nb, Ta)-(Mo, W)-B system by copper-mold casting. The ring-shaped glassy Fe-(Al, Ga)-(P, C, B, Si) alloys exhibit much better soft magnetic properties as compared with the ring-shaped alloy made from the melt-spun ribbon because of the formation of the unique domain structure. The good combination of high glass-forming ability and good soft magnetic properties indicates the possibility of future development as a new bulk glassy magnetic material

  20. Selfish X chromosomes and speciation.

    Science.gov (United States)

    Patten, Manus M

    2017-12-27

    In two papers published at about the same time almost thirty years ago, Frank (Evolution, 45, 1991a, 262) and Hurst and Pomiankowski (Genetics, 128, 1991, 841) independently suggested that divergence of meiotic drive systems-comprising genes that cheat meiosis and genes that suppress this cheating-might provide a general explanation for Haldane's rule and the large X-effect in interspecific hybrids. Although at the time, the idea was met with skepticism and a conspicuous absence of empirical support, the tide has since turned. Some of the clearest mechanistic explanations we have for hybrid male sterility involve meiotic drive systems, and several other cases of hybrid sterility are suggestive of a role for meiotic drive. In this article, I review these ideas and their descendants and catalog the current evidence for the meiotic drive model of speciation. In addition, I suggest that meiotic drive is not the only intragenomic conflict to involve the X chromosome and contribute to hybrid incompatibility. Sexually and parentally antagonistic selection pressures can also pit the X chromosome and autosomes against each other. The resulting intragenomic conflicts should lead to co-evolution within populations and divergence between them, thus increasing the likelihood of incompatibilities in hybrids. I provide a sketch of these ideas and interpret some empirical patterns in the light of these additional X-autosome conflicts. © 2017 John Wiley & Sons Ltd.

  1. Molecular activation analysis for chemical speciation studies

    International Nuclear Information System (INIS)

    Chai-Chifang

    1998-01-01

    The term of Molecular Activation Analysis (MAA) refers to an activation analysis method that is able to provide information about the chemical species of elements in system of interests, though its definition has remained to be assigned. Its development is strongly stimulated by the urgent need to know the chemical species of elements, because the total concentrations are often without any meaning when assessing health or environmental risks of trace elements.In practice, the MAA is a combination of conventional instrumental or radiochemical activation analysis and physical, chemical or biochemical separation techniques. The MAA is able to play a particular role in speciation studies. However, the critical point in the MAA is that it is not permitted to change the primitive chemical species of elements in systems, or the change has to be under control; in the meantime it is not allowed to form the 'new artifact' originally not present in systems. Some practical examples of MAA for chemical species research performed recently in our laboratory will be presented as follows: Chemical species of platinum group elements in sediment; Chemical species of iodine in marine algae; Chemical species of mercury in human tissues; Chemical species of selenium in corn; Chemical species of rare earth elements in natural plant, etc. The merits and limitations of MAA will be described as well. (author)

  2. Speciation of arsenic, selenium, and chromium in wildfire impacted soils and ashes

    Science.gov (United States)

    Wolf, Ruth E.; Hoefen, Todd M.; Hageman, Philip L.; Morman, Suzette A.; Plumlee, Geoffrey S.

    2010-01-01

    In 2007-09, California experienced several large wildfires that damaged large areas of forest and destroyed many homes and buildings. The U.S. Geological Survey collected samples from the Harris, Witch, Grass Valley, Ammo, Santiago, Canyon, Jesusita, and Station fires for testing to identify any possible characteristics of the ashes and soils from burned areas that may be of concern for their impact on water quality, human health, and endangered species. The samples were subjected to analysis for bulk chemical composition for 44 elements by inductively coupled plasma mass spectrometry (ICP-MS) after acid digestion and de-ionized water leach tests for pH, alkalinity, conductivity, and anions. Water leach tests generated solutions ranging from pH 10-12, suggesting that ashes can generate caustic alkalinity in contact with rainwater or body fluids (for example, sweat and fluids in the respiratory tract). Samples from burned residential areas in the 2007 fires had elevated levels for several metals, including: As, Pb, Sb, Cu, Zn, and Cr. In some cases, the levels found were above the U.S. Environmental Protection Agency (USEPA) preliminary remediation goals (PRG) for soils. Speciation analyses were conducted on de-ionized water and simulated lung fluid leachates for As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI). All species were determined in the same analytical run using an ion-pairing HPLC-ICP-MS method. For leachates containing high levels of total Cr, the majority of the chromium was present in the hexavalent, Cr(VI), form. Higher total and hexavalent chromium levels were observed for samples collected from burned residential areas. Arsenic was also generally present in the more oxidized, As(V), form. Selenium (IV) and (VI) were present, but typically at levels below 2 ppb for most samples. Stability studies of leachate solutions under different storage conditions were performed and the suitability of different sample preservation methods for speciation

  3. How Facilitation May Interfere with Ecological Speciation

    Directory of Open Access Journals (Sweden)

    P. Liancourt

    2012-01-01

    Full Text Available Compared to the vast literature linking competitive interactions and speciation, attempts to understand the role of facilitation for evolutionary diversification remain scarce. Yet, community ecologists now recognize the importance of positive interactions within plant communities. Here, we examine how facilitation may interfere with the mechanisms of ecological speciation. We argue that facilitation is likely to (1 maintain gene flow among incipient species by enabling cooccurrence of adapted and maladapted forms in marginal habitats and (2 increase fitness of introgressed forms and limit reinforcement in secondary contact zones. Alternatively, we present how facilitation may favour colonization of marginal habitats and thus enhance local adaptation and ecological speciation. Therefore, facilitation may impede or pave the way for ecological speciation. Using a simple spatially and genetically explicit modelling framework, we illustrate and propose some first testable ideas about how, when, and where facilitation may act as a cohesive force for ecological speciation. These hypotheses and the modelling framework proposed should stimulate further empirical and theoretical research examining the role of both competitive and positive interactions in the formation of incipient species.

  4. Speciation of zinc in contaminated soils

    International Nuclear Information System (INIS)

    Stephan, Chadi H.; Courchesne, Francois; Hendershot, William H.; McGrath, Steve P.; Chaudri, Amar M.; Sappin-Didier, Valerie; Sauve, Sebastien

    2008-01-01

    The chemical speciation of zinc in soil solutions is critical to the understanding of its bioavailability and potential toxic effects. We studied the speciation of Zn in soil solution extracts from 66 contaminated soils representative of a wide range of field conditions in both North America and Europe. Within this dataset, we evaluated the links among the dissolved concentrations of zinc and the speciation of Zn 2+ , soil solution pH, total soil Zn, dissolved organic matter (DOM), soil organic matter (SOM) and the concentrations of different inorganic anions. The solid-liquid partitioning coefficient (K d ) for Zn ranged from 17 to 13,100 L kg -1 soil. The fraction of dissolved Zn bound to DOM varied from 60% to 98% and the soil solution free Zn 2+ varied from 40% to 60% of the labile Zn. Multiple regression equations to predict free Zn 2+ , dissolved Zn and the solid-liquid partitioning of Zn are given for potential use in environmental fate modeling and risk assessment. The multiple regressions also highlight some of the most important soil properties controlling the solubility and chemical speciation of zinc in contaminated soils. - We studied the relationships among the chemical speciation of Zn in soil solution extracts from 66 contaminated soils and various physicochemical properties of the soils

  5. Speciation by Symbiosis: the Microbiome and Behavior.

    Science.gov (United States)

    Shropshire, J Dylan; Bordenstein, Seth R

    2016-03-31

    Species are fundamental units of comparison in biology. The newly discovered importance and ubiquity of host-associated microorganisms are now stimulating work on the roles that microbes can play in animal speciation. We previously synthesized the literature and advanced concepts of speciation by symbiosis with notable attention to hybrid sterility and lethality. Here, we review recent studies and relevant data on microbes as players in host behavior and behavioral isolation, emphasizing the patterns seen in these analyses and highlighting areas worthy of additional exploration. We conclude that the role of microbial symbionts in behavior and speciation is gaining exciting traction and that the holobiont and hologenome concepts afford an evolving intellectual framework to promote research and intellectual exchange between disciplines such as behavior, microbiology, genetics, symbiosis, and speciation. Given the increasing centrality of microbiology in macroscopic life, microbial symbiosis is arguably the most neglected aspect of animal and plant speciation, and studying it should yield a better understanding of the origin of species. Copyright © 2016 Shropshire and Bordenstein.

  6. Characterisation of bulk solids

    Energy Technology Data Exchange (ETDEWEB)

    D. McGlinchey [Glasgow Caledonian University, Glasgow (United Kingdom). Centre for Industrial Bulk Solids Handling

    2005-07-01

    Handling of powders and bulk solids is a critical industrial technology across a broad spectrum of industries, including minerals processing. With contributions from leading authors in their respective fields, this book provides the reader with a sound understanding of the techniques, importance and application of particulate materials characterisation. It covers the fundamental characteristics of individual particles and bulk particulate materials, and includes discussion of a wide range of measurement techniques, and the use of material characteristics in design and industrial practice. Contents: Characterising particle properties; Powder mechanics and rheology; Characterisation for hopper and stockpile design; Fluidization behaviour; Characterisation for pneumatic conveyor design; Explosiblility; 'Designer' particle characteristics; Current industrial practice; and Future trends. 130 ills.

  7. Atmospheric speciation of mercury in two contrasting Southeastern US airsheds

    Science.gov (United States)

    Gabriel, Mark C.; Williamson, Derek G.; Brooks, Steve; Lindberg, Steve

    Simultaneous measurement of gaseous elemental, reactive gaseous, and fine particulate mercury took place in Tuscaloosa AL, (urban airshed) and Cove Mountain, TN (non-urban airshed) during the summers of 2002 and 2003. The objective of this research was to (1) summarize the temporal distribution of each mercury specie at each site and compare to other speciation data sets developed by other researchers and (2) provide insight into urban and non-urban mercury speciation effects using various statistical methods. Average specie concentrations were as follows: 4.05 ng m -3 (GEM), 13.6 pg m -3 (RGM), 16.4 pg m -3 (Hg-p) for Tuscaloosa; 3.20 ng m -3 (GEM), 13.6 pg m -3 (RGM), 9.73 pg m -3 (Hg-p) for Cove Mountain. As a result of urban airshed impacts, short periods of high concentration for all mercury species was common in Tuscaloosa. At Cove Mountain a consistent mid-day rise and evening drop for mercury species was found. This pattern was primarily the result of un-impacted physical boundary layer movement, although, other potential impacts were ambient photochemistry and air-surface exchange of mercury. Meteorological parameters that are known to heavily impact mercury speciation were similar for the study period for Tuscaloosa and Cove Mountain except for wind speed (m s -1), which was higher at Cove Mountain. For both sites statistically significant ( p<0.0001), inverse relationships existed between wind speed and Hg 0 concentration. A weaker windspeed-Hg 0 correlation existed for Tuscaloosa. By analyzing Hg concentration—wind speed magnitude change at both sites it was found that wind speed at Cove Mountain had a greater influence on Hg 0 concentration variability than Tuscaloosa by a factor of 3. Using various statistical tests, we concluded that the nature of Tuscaloosa's atmospheric mercury speciation was the result of typical urban airshed impacts. Cove Mountain showed atmospheric mercury speciation characteristics indicative of a non-urban area along with

  8. Micromegas in a bulk

    International Nuclear Information System (INIS)

    Giomataris, I.; De Oliveira, R.; Andriamonje, S.; Aune, S.; Charpak, G.; Colas, P.; Fanourakis, G.; Ferrer, E.; Giganon, A.; Rebourgeard, Ph.; Salin, P.

    2006-01-01

    In this paper, we present a novel way to manufacture the bulk Micromegas detector. A simple process based on the Printed Circuit Board (PCB) technology is employed to produce the entire sensitive detector. Such a fabrication process could be extended to very large area detectors made by the industry. The low cost fabrication together with the robustness of the electrode materials will make it attractive for several applications ranging from particle physics and astrophysics to medicine

  9. Effects of pH on the speciation of radionuclides in groundwater of beishan area, gansu province, China

    International Nuclear Information System (INIS)

    Zhanshi, Zhang; Wenbin, Zhou; Xianhua, Fan

    2002-01-01

    Speciation of radioactive nuclides is one of the most important factors in the study of migration and precipitation of the nuclides related to deep geological disposal of high level radwastes (HLW). Theoretical speciation analysis with thermodynamic equilibrium codes is an effective method. The authors have employed the EQ3NR, a computer program for geochemical aqueous speciation-solubility calculation, to evaluate the speciation of the key nuclides in the groundwater of Beishan Area, a potential area for hosting the HLW Repository of China. The calculated results showed that pH value as well as chemical composition of the water had a great impact on the speciation of key nuclides, such as Np, Pu, Am, U and Th, which would be released from HLW to the groundwater of Beishan Area. In addition, it was found that the speciation of nuclides varied from one to another. However, under alkaline conditions, the speciations were relatively simpler and hydroxyl complexes and carbonate complexes were dominant. (author)

  10. Quantitative HPLC-ICP-MS analysis of antimony redox speciation in complex sample matrices: new insights into the Sb-chemistry causing poor chromatographic recoveries

    DEFF Research Database (Denmark)

    Hansen, Claus; Schmidt, Bjørn; Larsen, Erik Huusfeldt

    2011-01-01

    In solution antimony exists either in the pentavalent or trivalent oxidation state. As Sb(III) is more toxic than Sb(V), it is important to be able to perform a quantitative speciation analysis of Sb’s oxidation state. The most commonly applied chromatographic methods used for this redox speciation...

  11. Anaerobic Digestion Alters Copper and Zinc Speciation.

    Science.gov (United States)

    Legros, Samuel; Levard, Clément; Marcato-Romain, Claire-Emmanuelle; Guiresse, Maritxu; Doelsch, Emmanuel

    2017-09-19

    Anaerobic digestion is a widely used organic waste treatment process. However, little is known on how it could alter the speciation of contaminants in organic waste. This study was focused on determining the influence of anaerobic digestion on the speciation of copper and zinc, two metals that generally occur at high concentration in organic waste. Copper and zinc speciation was investigated by X-ray absorption spectroscopy in four different raw organic wastes (predigestion) and their digested counterparts (postdigestion, i.e., digestates). The results highlighted an increase in the digestates of the proportion of amorphous or nanostructured copper sulfides as well as amorphous or nanostructured zinc sulfides and zinc phosphate as compared to raw waste. We therefore suggest that the environmental fate of these elements would be different when spreading either digestates or raw waste on cropland.

  12. Loss of speciation rate will impoverish future diversity

    OpenAIRE

    Rosenzweig, Michael L.

    2001-01-01

    Human activities have greatly reduced the amount of the earth's area available to wild species. As the area they have left declines, so will their rates of speciation. This loss of speciation will occur for two reasons: species with larger geographical ranges speciate faster; and loss of area drives up extinction rates, thus reducing the number of species available for speciation. Theory predicts steady states in species diversity, and fossils suggest that these have t...

  13. Hydrogen speciation in hydrated layers on nuclear waste glass

    International Nuclear Information System (INIS)

    Aines, R.D.; Weed, H.C.; Bates, J.K.

    1987-01-01

    The hydration of an outer layer on nuclear waste glasses is known to occur during leaching, but the actual speciation of hydrogen (as water or hydroxyl groups) in these layers has not been determined. As part of the Nevada Nuclear Waste Storage Investigations Project, we have used infrared spectroscopy to determine hydrogen speciations in three nuclear waste glass compositions (SRL-131 and 165, and PNL 76-68), which were leached at 90 0 C (all glasses) or hydrated in a vapor-saturated atmosphere at 202 0 C (SRL-131 only). Hydroxyl groups were found in the surface layers of all the glasses. Molecular water was found in the surface of SRL-131 and PNL 76-68 glasses that had been leached for several months in deionized water, and in the vapor-hydrated sample. The water/hydroxyl ratio increases with increasing reaction time; molecular water makes up most of the hydrogen in the thick reaction layers on vapor-phase hydrated glass while only hydroxyl occurs in the least reacted samples. Using the known molar absorptivities of water and hydroxyl in silica-rich glass the vapor-phase layer contained 4.8 moles/liter of molecular water, and 0.6 moles water in the form hydroxyl. A 15 μm layer on SRL-131 glass formed by leaching at 90 0 C contained a total of 4.9 moles/liter of water, 2/3 of which was as hydroxyl. The unreacted bulk glass contains about 0.018 moles/liter water, all as hydroxyl. The amount of hydrogen added to the SRL-131 glass was about 70% of the original Na + Li content, not the 300% that would result from alkali=hydronium ion interdiffusion. If all the hydrogen is then assumed to be added as the result of alkali-H + interdiffusion, the molecular water observed may have formed from condensation of the original hydroxyl groups

  14. Transuranium element behavior in the environment: What speciation studies can tell us

    International Nuclear Information System (INIS)

    Cleveland, J.M.

    1989-01-01

    Some of the transuranium elements - especially plutonium - can exist in the environment in several different oxidation states which differ chemically from one another as much as if they were different elements. Hence an understanding of the environmental chemistry of these elements requires knowledge of their oxidation-state distribution, or speciation, under a variety of realistic conditions. Such studies are in their infancy, but already several chemical speciation methods have yielded results indicating the uniqueness of transuranic environment chemistry; for example, dioxoplutonium(V), which is unstable in the acid solutions employed in laboratory and processing plant, is often the most prevalent plutonium oxidation state in natural waters. More sensitive and less invasive physical speciation methods under development will hopefully permit the extension of these studies to a wider variety of environmental conditions and to determinations of sorbed species necessary for an understanding of sorption processes

  15. Incidence and Speciation of Candida Species among Non-gravid ...

    African Journals Online (AJOL)

    This study investigated the incidence and speciation of Candida species among non-gravid young females, using commercially available chromogenic Candida speciation media (CHROM agar) for the identification/speciation of medically important yeast and yeastlike organisms in a routine clinical mycology laboratory.

  16. EPAs SPECIATE 4.4 Database: Development and Uses

    Science.gov (United States)

    SPECIATE is the U.S. Environmental Protection Agency’s (EPA) repository of source category-specific particulate matter (PM), volatile organic gas, and other gas speciation profiles of air pollutant emissions. Abt Associates, Inc. developed SPECIATE 4.4 through a collaborat...

  17. Changes in zinc speciation with mine tailings acidification in a semiarid weathering environment.

    Science.gov (United States)

    Hayes, Sarah M; O'Day, Peggy A; Webb, Sam M; Maier, Raina M; Chorover, Jon

    2011-09-01

    High concentrations of residual metal contaminants in mine tailings can be transported easily by wind and water, particularly when tailings remain unvegetated for decades following mining cessation, as is the case in semiarid landscapes. Understanding the speciation and mobility of contaminant metal(loid)s, particularly in surficial tailings, is essential to controlling their phytotoxicities and to revegetating impacted sites. In prior work, we showed that surficial tailings samples from the Klondyke State Superfund Site (AZ, USA), ranging in pH from 5.4 to 2.6, represent a weathering series, with acidification resulting from sulfide mineral oxidation, long-term Fe hydrolysis, and a concurrent decrease in total (6000 to 450 mg kg(-1)) and plant-available (590 to 75 mg kg(-1)) Zn due to leaching losses and changes in Zn speciation. Here, we used bulk and microfocused Zn K-edge X-ray absorption spectroscopy (XAS) data and a six-step sequential extraction procedure to determine tailings solid phase Zn speciation. Bulk sample spectra were fit by linear combination using three references: Zn-rich phyllosilicate (Zn(0.8)talc), Zn sorbed to ferrihydrite (Zn(adsFeOx)), and zinc sulfate (ZnSO(4) · 7H(2)O). Analyses indicate that Zn sorbed in tetrahedral coordination to poorly crystalline Fe and Mn (oxyhydr)oxides decreases with acidification in the weathering sequence, whereas octahedral zinc in sulfate minerals and crystalline Fe oxides undergoes a relative accumulation. Microscale analyses identified hetaerolite (ZnMn(2)O(4)), hemimorphite (Zn(4)Si(2)O(7)(OH)(2) · H(2)O) and sphalerite (ZnS) as minor phases. Bulk and microfocused spectroscopy complement the chemical extraction results and highlight the importance of using a multimethod approach to interrogate complex tailings systems.

  18. Microimaging and tomography with chemical speciation

    Energy Technology Data Exchange (ETDEWEB)

    Rau, C. E-mail: rau@esrf.fr; Somogyi, A.; Simionovici, A

    2003-01-01

    Materials science deals with the study of the morphology of samples, their chemical composition and the relation between both. One general problem is the preservation of the sample throughout the different analyses, like it is often the case for classical chemical analysis. Destruction-free chemical speciation in three dimensions with micrometer resolution can be achieved by combining X-ray spectroscopy and imaging techniques. Highly brilliant radiation is needed for this purpose available at 3rd generation synchrotrons such as the ESRF. X-ray absorption near-edge spectroscopy (XANES) is a non-destructive well-known and established technique in chemistry. By scanning the X-ray energy in the vicinity (50-100 eV) of the absorption edge of an element, information can be obtained about the oxidation state of the probed atoms. The (conventional) technique mainly employed until now applies to homogeneous, specifically prepared flat samples where the measured signal can be considered as the average over the whole irradiated volume. This restriction for samples is partially released when the XANES method is combined with imaging techniques. 2D resolved data is acquired using area detectors or by scanning with a focussed beam. X-ray absorption tomography is a method of choice for investigating the 3D structure of objects and its dual energy version is used for getting information about the 3D distribution of a given element within the sample. Although the combination of XANES and tomography seems to be a natural extension of dual-energy tomography, in practice several experimental problems have to be overcome in order to obtain useable data. In the following we describe the results of XANES imaging and tomography obtained measuring a phantom sample of pure molybdenum compounds using a FreLoN 2000 camera system at the ESRF undulator beamline ID22. This system allowed making volume resolved distinctions between different oxidation states with spatial resolution in the

  19. Actinide speciation in the environment

    International Nuclear Information System (INIS)

    Choppin, G.R.

    2007-01-01

    Nuclear test explosions and nuclear reactor wastes and accidents have released large amounts of radioactivity into the environment. Actinide ions in waters often are not in a state of thermodynamic equilibrium and their solubility and migration behavior is related to the form in which the nuclides are introduced into the aquatic system. Chemical speciation, oxidation state, redox reactions, and sorption characteristics are necessary in predicting solubility of the different actinides, their migration behaviors and their potential effects on marine biota. The most significant of these variables is the oxidation state of the metal ion as the simultaneous presence of more than one oxidation state for some actinides in a solution complicates actinide environmental behavior. Both Np(V)O 2 + and Pu(V)O 2 + , the most significant soluble states in natural oxic waters, are relatively noncomplexing and resistant to hydrolysis and subsequent precipitation. The solubility of NpO 2 + can be as high as 10 -4 M while that of PuO 2 + is much more limited by reduction to the insoluble tetravalent species, Pu(OH) 4 , (pK sp ≥56) but which can be present in the pentavalent form in aqautic phases as colloidal material. The solubility of hexavalent UO 2 2+ in sea water is relatively high due to formation of carbonate complexes. The insoluble trivalent americium hydroxocarbonate, Am(OH)(CO 3 ) is the limiting species for the solubility of Am(III) in sea water. Thorium(IV) is present as Th(OH) 4 , in colloidal form. The chemistry of actinide ions in the environment is reviewed to show the spectrum of reactions that can occur in natural waters which must be considered in assessing the environmental behavior of actinides. Much is understood about sorption of actinides on surfaces, the mode of migration of actinides in such waters and the potential effects of these radioactive species on marine biota, but much more understanding of the behavior of the actinides in the environment is

  20. WHATIF-AQ, Geochem Speciation and Saturation of Aqueous Solution

    International Nuclear Information System (INIS)

    Nielsen, Ole John; Jensen, Bror Skytte

    1988-01-01

    1 - Description of program or function: WHATIF-AQ is part of a family of programs for calculations of geochemistry in the near-field of radioactive waste with temperature gradients. The program calculates speciation and saturation indices for an aqueous solution at temperatures in the range 0 - 125 degrees C. The chemical equilibrium is determined by solving a set of nonlinear equations consisting of the equilibrium constant and mass balance constraints. 2 - Method of solution: The set of equations is solved using a generalized Newton-Raphson technique

  1. Modified Extraction-Free Ion-Pair Methods for the Determination of Flunarizine Dihydrochloride in Bulk Drug, Tablets, and Human Urine

    Science.gov (United States)

    Prashanth, K. N.; Basavaiah, K.

    2018-01-01

    Two simple and sensitive extraction-free spectrophotometric methods are described for the determination of flunarizine dihydrochloride. The methods are based on the ion-pair complex formation between the nitrogenous compound flunarizine (FNZ), converted from flunarizine dihydrochloride (FNH), and the acidic dye phenol red (PR), in which experimental variables were circumvented. The first method (method A) is based on the formation of a yellow-colored ion-pair complex (1:1 drug:dye) between FNZ and PR in chloroform, which is measured at 415 nm. In the second method (method B), the formed drug-dye ion-pair complex is treated with ethanolic potassium hydroxide in an ethanolic medium, and the resulting base form of the dye is measured at 580 nm. The stoichiometry of the formed ion-pair complex between the drug and dye (1:1) is determined by Job's continuous variations method, and the stability constant of the complex is also calculated. These methods quantify FNZ over the concentration ranges 5.0-70.0 in method A and 0.5-7.0 μg/mL in method B. The calculated molar absorptivities are 6.17 × 103 and 5.5 × 104 L/mol·cm-1 for method A and method B, respectively, with corresponding Sandell sensitivity values of 0.0655 and 0.0074 μg/cm2. The methods are applied to the determination of FNZ in pure drug and human urine.

  2. Potential application of SERS for arsenic speciation in biological matrices.

    Science.gov (United States)

    Yang, Mingwei; Matulis, Shannon; Boise, Lawrence H; McGoron, Anthony J; Cai, Yong

    2017-08-01

    Speciation of arsenic is usually carried out using chromatography-based methods coupled with spectroscopic determination; however, the inevitable procedures involving sample preparation and separation could potentially alter the integrity of the arsenic metabolites present in biological samples. Surface-enhanced Raman spectroscopy (SERS) could be a promising alternative for providing a reliable arsenic analysis under the influence of a cellular matrix. A method for arsenic speciation using SERS in cellular matrix was developed in this study and four arsenicals were selected, including arsenite (As III ), arsenate (As V ), monomethylarsonic acid (MMA V ) and dimethylarsinic acid (DMA V ). Silver nanoparticles in the form of colliodal suspension with different surface charges, i.e., coated with citrate (AgNPs-Citrate) and spermine (AgNPs-Spermine) were employed as SERS substrates. Adsorption of arsenicals on nanoparticles in colloidal suspensions and the cellular matrix and the pH, size, and zeta potential of the colloidal suspensions were investigated for a better understanding of the SERS signal response of arsenicals in the colloidal suspensions or under the influence of cellular matrix. Arsenicals showed substantially different SERS responses in the two colloidal suspensions, mainly because of the distinct difference in the interaction between the arsenicals and the nanoparticles. Arsenic speciation in cell lysate could be successfully carried out in AgNPs-Spermine suspension, while AgNPs-Citrate could not yield significant SERS signals under the experimental conditions. This study proved that AgNPs-Spermine colloidal suspension could be a promising SERS substrate for studying arsenic metabolism in a biological matrix, reducing the bias caused by traditional techniques that involve sample extraction and pretreatment.

  3. Electrochemical metal speciation in colloidal dispersions

    NARCIS (Netherlands)

    Wonders, J.H.A.M.

    1995-01-01

    The term "heavy metals" is connected with toxicity. They form strong complexes with enzymes, other proteins and DNA in living organisms, which causes dysfunctioning and hence poisoning. In combination with the uptake mechanism of the organism, speciation of heavy metal determines the

  4. Magic cues versus magic preferences in speciation

    NARCIS (Netherlands)

    Maan, Martine E.; Seehausen, Ole

    Question: How does divergent natural selection lead to divergence in mating traits and the evolution of reproductive isolation? Background: Ecological speciation of non-allopatric taxa usually requires the evolution of an association between selective mating and the traits underlying ecological

  5. Biogeochemical speciation of Fe in ocean water

    NARCIS (Netherlands)

    Hiemstra, T.; Riemsdijk, van W.H.

    2006-01-01

    The biogeochemical speciation of Fe in seawater has been evaluated using the consistent Non-Ideal Competitive Adsorption model (NICA¿Donnan model). Two types of data sets were used, i.e. Fe-hydroxide solubility data and competitive ligand equilibration/cathodic stripping voltammetry (CLE/CSV) Fe

  6. Biosensor for metal analysis and speciation

    Science.gov (United States)

    Aiken, Abigail M.; Peyton, Brent M.; Apel, William A.; Petersen, James N.

    2007-01-30

    A biosensor for metal analysis and speciation is disclosed. The biosensor comprises an electron carrier immobilized to a surface of an electrode and a layer of an immobilized enzyme adjacent to the electrode. The immobilized enzyme comprises an enzyme having biological activity inhibited by a metal to be detected by the biosensor.

  7. Analytical methodologies for aluminium speciation in environmental and biological samples--a review.

    Science.gov (United States)

    Bi, S P; Yang, X D; Zhang, F P; Wang, X L; Zou, G W

    2001-08-01

    It is recognized that aluminium (Al) is a potential environmental hazard. Acidic deposition has been linked to increased Al concentrations in natural waters. Elevated levels of Al might have serious consequences for biological communities. Of particular interest is the speciation of Al in aquatic environments, because Al toxicity depends on its forms and concentrations. In this paper, advances in analytical methodologies for Al speciation in environmental and biological samples during the past five years are reviewed. Concerns about the specific problems of Al speciation and highlights of some important methods are elucidated in sections devoted to hybrid techniques (HPLC or FPLC coupled with ET-AAS, ICP-AES, or ICP-MS), flow-injection analysis (FIA), nuclear magnetic resonance (27Al NMR), electrochemical analysis, and computer simulation. More than 130 references are cited.

  8. Analytical developments in ICP-MS for arsenic and selenium speciation. Application to granitic waters

    International Nuclear Information System (INIS)

    Garraud, Herve

    1999-01-01

    Nuclear waste storage in geological areas needs the understanding of the physico-chemistry of groundwaters interactions with surrounding rocks. Redox potential measurements and speciation, calculated from geochemical modelling are not significant for the determination of water reactivity. We have thus chosen to carry out experimental speciation by developing sensitive analytical tools with respect of specie chemical identity. We have studied two redox indicators from reference sites (thermal waters from Pyrenees, France): arsenic and selenium. At first, we have determined the concentrations in major ions (sulphide, sulphate, chloride, fluoride, carbonate, Na, K, Ca). Speciation was conducted by HPLC hyphenated to quadrupole ICP-MS and high resolution ICP-MS. These analyses have shown the presence of two new arsenic species in solution, in addition of a great reactivity of these waters during stability studies. A sampling, storage and analysis method is described. (author) [fr

  9. Factors Controlling Redox Speciation of Plutonium and Neptunium in Extraction Separation Processes

    Energy Technology Data Exchange (ETDEWEB)

    Paulenova, Alena [Principal Investigator; Vandegrift, III, George F. [Collaborator

    2013-09-24

    The objective of the project was to examine the factors controlling redox speciation of plutonium and neptunium in UREX+ extraction in terms of redox potentials, redox mechanism, kinetics and thermodynamics. Researchers employed redox-speciation extractions schemes in parallel to the spectroscopic experiments. The resulting distribution of redox species w studied uring spectroscopic, electrochemical, and spectro-electrochemical methods. This work reulted in collection of data on redox stability and distribution of redox couples in the nitric acid/nitrate electrolyte and the development of redox buffers to stabilize the desired oxidation state of separated radionuclides. The effects of temperature and concentrations on the redox behavior of neptunium were evaluated.

  10. Polarographic validation of chemical speciation models

    International Nuclear Information System (INIS)

    Duffield, J.R.; Jarratt, J.A.

    2001-01-01

    It is well established that the chemical speciation of an element in a given matrix, or system of matrices, is of fundamental importance in controlling the transport behaviour of the element. Therefore, to accurately understand and predict the transport of elements and compounds in the environment it is a requirement that both the identities and concentrations of trace element physico-chemical forms can be ascertained. These twin requirements present the analytical scientist with considerable challenges given the labile equilibria, the range of time scales (from nanoseconds to years) and the range of concentrations (ultra-trace to macro) that may be involved. As a result of this analytical variability, chemical equilibrium modelling has become recognised as an important predictive tool in chemical speciation analysis. However, this technique requires firm underpinning by the use of complementary experimental techniques for the validation of the predictions made. The work reported here has been undertaken with the primary aim of investigating possible methodologies that can be used for the validation of chemical speciation models. However, in approaching this aim, direct chemical speciation analyses have been made in their own right. Results will be reported and analysed for the iron(II)/iron(III)-citrate proton system (pH 2 to 10; total [Fe] = 3 mmol dm -3 ; total [citrate 3- ] 10 mmol dm -3 ) in which equilibrium constants have been determined using glass electrode potentiometry, speciation is predicted using the PHREEQE computer code, and validation of predictions is achieved by determination of iron complexation and redox state with associated concentrations. (authors)

  11. Bulk and Surface Aqueous Speciation of Calcite: Implications for Low-Salinity Waterflooding of Carbonate Reservoirs

    KAUST Repository

    Yutkin, Maxim P.; Mishra, Himanshu; Patzek, Tadeusz; Lee, John; Radke, Clayton J.

    2017-01-01

    and surface equilibria draws several important inferences about the proposed LSW oil-recovery mechanisms. Diffuse double-layer expansion (DLE) is impossible for brine ionic strength greater than 0.1 molar. Because of rapid rock/brine equilibration

  12. Bulk velocity extraction for nano-scale Newtonian flows

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Wenfei, E-mail: zwenfei@gmail.com [Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures of Hebei Province, Yanshan University, Qinhuangdao 066004 (China); Sun, Hongyu [Key Laboratory of Mechanical Reliability for Heavy Equipments and Large Structures of Hebei Province, Yanshan University, Qinhuangdao 066004 (China)

    2012-04-16

    The conventional velocity extraction algorithm in MDS method has difficulty to determine the small flow velocity. This study proposes a new method to calculate the bulk velocity in nano-flows. Based on the Newton's law of viscosity, according to the calculated viscosities and shear stresses, the flow velocity can be obtained by numerical integration. This new method can overcome the difficulty existed in the conventional MDS method and improve the stability of the computational process. Numerical results show that this method is effective for the extraction of bulk velocity, no matter the bulk velocity is large or small. -- Highlights: ► Proposed a new method to calculate the bulk velocity in nano-flows. ► It is effective for the extraction of small bulk velocity. ► The accuracy, convergence and stability of the new method is good.

  13. Bulk velocity extraction for nano-scale Newtonian flows

    International Nuclear Information System (INIS)

    Zhang, Wenfei; Sun, Hongyu

    2012-01-01

    The conventional velocity extraction algorithm in MDS method has difficulty to determine the small flow velocity. This study proposes a new method to calculate the bulk velocity in nano-flows. Based on the Newton's law of viscosity, according to the calculated viscosities and shear stresses, the flow velocity can be obtained by numerical integration. This new method can overcome the difficulty existed in the conventional MDS method and improve the stability of the computational process. Numerical results show that this method is effective for the extraction of bulk velocity, no matter the bulk velocity is large or small. -- Highlights: ► Proposed a new method to calculate the bulk velocity in nano-flows. ► It is effective for the extraction of small bulk velocity. ► The accuracy, convergence and stability of the new method is good.

  14. Bulk muscles, loose cables.

    Science.gov (United States)

    Liyanage, Chamari R D G; Kodali, Venkata

    2014-10-17

    The accessibility and usage of body building supplements is on the rise with stronger internet marketing strategies by the industry. The dangers posed by the ingredients in them are underestimated. A healthy young man came to the emergency room with palpitations and feeling unwell. Initial history and clinical examination were non-contributory to find the cause. ECG showed atrial fibrillation. A detailed history for any over the counter or herbal medicine use confirmed that he was taking supplements to bulk muscle. One of the components in these supplements is yohimbine; the onset of symptoms coincided with the ingestion of this product and the patient is symptom free after stopping it. This report highlights the dangers to the public of consuming over the counter products with unknown ingredients and the consequential detrimental impact on health. 2014 BMJ Publishing Group Ltd.

  15. Novel kinetic spectrophotometric method for estimation of certain biologically active phenolic sympathomimetic drugs in their bulk powders and different pharmaceutical formulations

    Science.gov (United States)

    Omar, Mahmoud A.; Badr El-Din, Khalid M.; Salem, Hesham; Abdelmageed, Osama H.

    2018-03-01

    A simple, selective and sensitive kinetic spectrophotometric method was described for estimation of four phenolic sympathomimetic drugs namely; terbutaline sulfate, fenoterol hydrobromide, isoxsuprine hydrochloride and etilefrine hydrochloride. This method is depended on the oxidation of the phenolic drugs with Folin-Ciocalteu reagent in presence of sodium carbonate. The rate of color development at 747-760 nm was measured spectrophotometrically. The experimental parameters controlling the color development were fully studied and optimized. The reaction mechanism for color development was proposed. The calibration graphs for both the initial rate and fixed time methods were constructed, where linear correlations were found in the general concentration ranges of 3.65 × 10- 6-2.19 × 10- 5 mol L- 1 and 2-24.0 μg mL- 1 with correlation coefficients in the following range 0.9992-0.9999, 0.9991-0.9998 respectively. The limits of detection and quantitation for the initial rate and fixed time methods were found to be in general concentration range 0.109-0.273, 0.363-0.910 and 0.210-0.483, 0.700-1.611 μg mL- 1 respectively. The developed method was validated according to ICH and USP 30 -NF 25 guidelines. The suggested method was successfully implemented to the estimation of these drugs in their commercial pharmaceutical formulations and the recovery percentages obtained were ranged from 97.63% ± 1.37 to 100.17% ± 0.95 and 97.29% ± 0.74 to 100.14 ± 0.81 for initial rate and fixed time methods respectively. The data obtained from the analysis of dosage forms were compared with those obtained by reported methods. Statistical analysis of these results indicated no significant variation in the accuracy and precision of both the proposed and reported methods.

  16. Development of superconductor bulk for superconductor bearing

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Chan Joong; Jun, Byung Hyuk; Park, Soon Dong (and others)

    2008-08-15

    Current carrying capacity is one of the most important issues in the consideration of superconductor bulk materials for engineering applications. There are numerous applications of Y-Ba-Cu-O (YBCO) bulk superconductors e.g. magnetic levitation train, flywheel energy storage system, levitation transportation, lunar telescope, centrifugal device, magnetic shielding materials, bulk magnets etc. Accordingly, to obtain YBCO materials in the form of large, single crystals without weak-link problem is necessary. A top seeded melt growth (TSMG) process was used to fabricate single crystal YBCO bulk superconductors. The seeded and infiltration growth (IG) technique was also very promising method for the synthesis of large, single-grain YBCO bulk superconductors with good superconducting properties. 5 wt.% Ag doped Y211 green compacts were sintered at 900 .deg. C {approx} 1200 .deg.C and then a single crystal YBCO was fabricated by an infiltration method. A refinement and uniform distribution of the Y211 particles in the Y123 matrix were achieved by sintering the Ag-doped samples. This enhancement of the critical current density was ascribable to a fine dispersion of the Y211 particles, a low porosity and the presence of Ag particles. In addition, we have designed and manufactured large YBCO single domain with levitation force of 10-13 kg/cm{sup 2} using TSMG processing technique.

  17. Speciation and migration of 129I in soil profiles

    International Nuclear Information System (INIS)

    Luo, Maoyi; Hou, Xiaolin; Zhou, Weijian; He, Chaohui; Chen, Ning; Liu, Qi; Zhang, Luoyuan

    2013-01-01

    A method has been developed for speciation analysis of ultra low level 129 I in soil using sequential extraction combined with coprecipitation for separation of carrier free iodine and AMS measurement of 129 I. Two loess profiles collected from northwest China were analyzed for species of 129 I and 127 I. Similar partitioning of 129 I and 127 I was observed in the loess profiles, the distribution of iodine isotopes followed an order of organic > leachable > reducible > residue. The 129 I concentrations and 129 I/ 127 I ratios decreased exponentially with the depth, and 2 orders of magnitude lower in the deepest layer (60 and 90 cm) compared with the top layer, indicating a significant contribution of anthropogenic input in the upper layer, and high retention of 129 I in soil. The mobility of 129 I in different fractions decreased in an order of leachable > organic > oxides > residue. The results suggest that migration of iodine downwards in the soil profile is a slow process; the oxides and residue are the less mobile fractions of iodine. Highlights: ► 129 I concentration decreases exponentially with the depth of soil profile. ► The mobility of 129 I in fractions decreases: leachable > organic > oxides > residue. ► Iodine shows less mobility in oxides and residue fractions. ► High organic soil content can effectively reduce the migration of 129 I in the environment. ► Carrier free iodine AMS is an effective method for natural 129 I speciation analysis in the environment

  18. Plant invasion and speciation along elevational gradients on the oceanic island La Palma, Canary Islands

    DEFF Research Database (Denmark)

    Steinbauer, Manuel; Irl, Severin David Howard; González-Mancebo, Juana Maria

    2017-01-01

    and anthropogenic filters, thus controlling the dispersal and establishment of species. Here, we investigate speciation and invasion processes along elevational gradients. Methods: We assess the vascular plant species richness as well as the number and percentage of endemic species and non-native species...

  19. Status of determining transuranic nuclides speciation in aqueous solution with laser spectrometry

    International Nuclear Information System (INIS)

    Wang Bo; Liu Dejun; Yao Jun; Chen Xi; Long Haoqi; Zeng Jishu; Su Xiguang; Fan Xianhua

    2007-01-01

    The knowledge about speciation of transuranic nuclides in aqueous solution is a basis for understanding the chemical and migration behavior of transuranic nuclides in aqueous solution. The speciation of transuranic nuclides with trace concentration is complicated in near neutral aqueous solutions, including change of oxidation state, complexation and colloid generation, etc. The concentrations of transuranium in near neutral aqueous solution usually below the sensitivity range of method such as conventional absorption spectroscopy. The radioactive analysis method has a very low detection limits for radionuclides, however, it wouldn' t allow the direct measurement of the transuranic species. In contrast with these methods, laser spectroscopy is an ideal method with high sensitivity, and non-contact and non-destructive for determining the speciation of transuranic nuclides. This paper summarizes the status and application of LIPAS (Laser-induced Photoacoustic Spectrometry), LIBD (Laser-induced Breakdown Detection) and TRLFS (Time-resolved Laser Fluorescence Spectrometry) to determine the speciation of transuranic nuclides with trace concentration in aqueous solutions. (authors)

  20. Speciation of actinides in aqueous solution by time-resolved laser-induced fluorescence spectroscopy (TRLFS)

    International Nuclear Information System (INIS)

    Kimura, Takaumi; Kato, Yoshiharu; Meinrath, G.; Yoshida, Zenko; Choppin, G.R.

    1995-01-01

    Time-resolved laser-induced fluorescence spectroscopy (TRLFS) as a sensitive and selective method has been applied to the speciation of actinides in aqueous solution. Studies on hydrolysis and carbonate complexation of U(VI) and on determination of hydration number of Cm(III) are reported. (author)

  1. Quantification of the boron speciation in alkali borosilicate glasses by electron energy loss spectroscopy

    DEFF Research Database (Denmark)

    Cheng, D.S.; Yang, G.; Zhao, Y.Q.

    2015-01-01

    developed a method based on electron energy loss spectroscopy (EELS) data acquisition and analyses, which enables determination of the boron speciation in a series of ternary alkali borosilicate glasses with constant molar ratios. A script for the fast acquisition of EELS has been designed, from which...

  2. Sulfur Speciation of Crude Oils by Partial Least Squares Regression Modeling of Their Infrared Spectra

    NARCIS (Netherlands)

    de Peinder, P.; Visser, T.; Wagemans, R.W.P.; Blomberg, J.; Chaabani, H.; Soulimani, F.; Weckhuysen, B.M.

    2013-01-01

    Research has been carried out to determine the feasibility of partial least-squares regression (PLS) modeling of infrared (IR) spectra of crude oils as a tool for fast sulfur speciation. The study is a continuation of a previously developed method to predict long and short residue properties of

  3. QbD-Based Development and Validation of a Stability-Indicating HPLC Method for Estimating Ketoprofen in Bulk Drug and Proniosomal Vesicular System.

    Science.gov (United States)

    Yadav, Nand K; Raghuvanshi, Ashish; Sharma, Gajanand; Beg, Sarwar; Katare, Om P; Nanda, Sanju

    2016-03-01

    The current studies entail systematic quality by design (QbD)-based development of simple, precise, cost-effective and stability-indicating high-performance liquid chromatography method for estimation of ketoprofen. Analytical target profile was defined and critical analytical attributes (CAAs) were selected. Chromatographic separation was accomplished with an isocratic, reversed-phase chromatography using C-18 column, pH 6.8, phosphate buffer-methanol (50 : 50v/v) as a mobile phase at a flow rate of 1.0 mL/min and UV detection at 258 nm. Systematic optimization of chromatographic method was performed using central composite design by evaluating theoretical plates and peak tailing as the CAAs. The method was validated as per International Conference on Harmonization guidelines with parameters such as high sensitivity, specificity of the method with linearity ranging between 0.05 and 250 µg/mL, detection limit of 0.025 µg/mL and quantification limit of 0.05 µg/mL. Precision was demonstrated using relative standard deviation of 1.21%. Stress degradation studies performed using acid, base, peroxide, thermal and photolytic methods helped in identifying the degradation products in the proniosome delivery systems. The results successfully demonstrated the utility of QbD for optimizing the chromatographic conditions for developing highly sensitive liquid chromatographic method for ketoprofen. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  4. Foliar or root exposures to smelter particles: Consequences for lead compartmentalization and speciation in plant leaves

    International Nuclear Information System (INIS)

    Schreck, Eva; Dappe, Vincent; Sarret, Géraldine; Sobanska, Sophie; Nowak, Dorota; Nowak, Jakub; Stefaniak, Elżbieta Anna; Magnin, Valérie; Ranieri, Vincent; Dumat, Camille

    2014-01-01

    In urban areas with high fallout of airborne particles, metal uptake by plants mainly occurs by foliar pathways and can strongly impact crop quality. However, there is a lack of knowledge on metal localization and speciation in plants after pollution exposure, especially in the case of foliar uptake. In this study, two contrasting crops, lettuce (Lactuca sativa L.) and rye-grass (Lolium perenne L.), were exposed to Pb-rich particles emitted by a Pb-recycling factory via either atmospheric or soil application. Pb accumulation in plant leaves was observed for both ways of exposure. The mechanisms involved in Pb uptake were investigated using a combination of microscopic and spectroscopic techniques (electron microscopy, laser ablation, Raman microspectroscopy, and X-ray absorption spectroscopy). The results show that Pb localization and speciation are strongly influenced by the type of exposure (root or shoot pathway) and the plant species. Foliar exposure is the main pathway of uptake, involving the highest concentrations in plant tissues. Under atmospheric fallouts, Pb-rich particles were strongly adsorbed on the leaf surface of both plant species. In lettuce, stomata contained Pb-rich particles in their apertures, with some deformations of guard cells. In addition to PbO and PbSO 4 , chemical forms that were also observed in pristine particles, new species were identified: organic compounds (minimum 20%) and hexagonal platy crystals of PbCO 3 . In rye-grass, the changes in Pb speciation were even more egregious: Pb–cell wall and Pb–organic acid complexes were the major species observed. For root exposure, identified here as a minor pathway of Pb transfer compared to foliar uptake, another secondary species, pyromorphite, was identified in rye-grass leaves. Finally, combining bulk and spatially resolved spectroscopic techniques permitted both the overall speciation and the minor but possibly highly reactive lead species to be determined in order to better

  5. Foliar or root exposures to smelter particles: Consequences for lead compartmentalization and speciation in plant leaves

    Energy Technology Data Exchange (ETDEWEB)

    Schreck, Eva [Université de Toulouse, INP, UPS, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, Avenue de l' Agrobiopole, 31326 Castanet-Tolosan (France); CNRS, EcoLab, 31326 Castanet-Tolosan (France); Géosciences Environnement Toulouse (GET), Observatoire Midi Pyrénées, Université de Toulouse, CNRS, IRD, 14 Avenue E. Belin, F-31400 Toulouse (France); Dappe, Vincent [LASIR (UMR CNRS 8516), Université de Lille 1, Bât. C5, 59655 Villeneuve d' Ascq Cedex (France); Sarret, Géraldine [ISTerre, UMR 5275, Université Grenoble I, CNRS, F-38041 Grenoble (France); Sobanska, Sophie [LASIR (UMR CNRS 8516), Université de Lille 1, Bât. C5, 59655 Villeneuve d' Ascq Cedex (France); Nowak, Dorota; Nowak, Jakub; Stefaniak, Elżbieta Anna [Department of Chemistry, John Paul II Catholic University of Lublin, Al. Kraśnicka 102, 20-718 Lublin (Poland); Magnin, Valérie [ISTerre, UMR 5275, Université Grenoble I, CNRS, F-38041 Grenoble (France); Ranieri, Vincent [CEA-INAC, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Dumat, Camille, E-mail: camille.dumat@ensat.fr [Université de Toulouse, INP, UPS, EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), ENSAT, Avenue de l' Agrobiopole, 31326 Castanet-Tolosan (France); CNRS, EcoLab, 31326 Castanet-Tolosan (France)

    2014-04-01

    In urban areas with high fallout of airborne particles, metal uptake by plants mainly occurs by foliar pathways and can strongly impact crop quality. However, there is a lack of knowledge on metal localization and speciation in plants after pollution exposure, especially in the case of foliar uptake. In this study, two contrasting crops, lettuce (Lactuca sativa L.) and rye-grass (Lolium perenne L.), were exposed to Pb-rich particles emitted by a Pb-recycling factory via either atmospheric or soil application. Pb accumulation in plant leaves was observed for both ways of exposure. The mechanisms involved in Pb uptake were investigated using a combination of microscopic and spectroscopic techniques (electron microscopy, laser ablation, Raman microspectroscopy, and X-ray absorption spectroscopy). The results show that Pb localization and speciation are strongly influenced by the type of exposure (root or shoot pathway) and the plant species. Foliar exposure is the main pathway of uptake, involving the highest concentrations in plant tissues. Under atmospheric fallouts, Pb-rich particles were strongly adsorbed on the leaf surface of both plant species. In lettuce, stomata contained Pb-rich particles in their apertures, with some deformations of guard cells. In addition to PbO and PbSO{sub 4}, chemical forms that were also observed in pristine particles, new species were identified: organic compounds (minimum 20%) and hexagonal platy crystals of PbCO{sub 3}. In rye-grass, the changes in Pb speciation were even more egregious: Pb–cell wall and Pb–organic acid complexes were the major species observed. For root exposure, identified here as a minor pathway of Pb transfer compared to foliar uptake, another secondary species, pyromorphite, was identified in rye-grass leaves. Finally, combining bulk and spatially resolved spectroscopic techniques permitted both the overall speciation and the minor but possibly highly reactive lead species to be determined in order to

  6. Contribution of analytical techniques coupled to the knowledge of the uranium speciation in natural conditions

    International Nuclear Information System (INIS)

    Petit, J.

    2009-06-01

    To understand the transport mechanisms and the radionuclides behaviour in the bio-geosphere is necessary to evaluate healthy and environmental risks of nuclear industry. These mechanisms are monitored by radioelements speciation, namely the distribution between their different physico-chemical forms in the environment. From this perspective, this PhD thesis deals with uranium speciation in a natural background. A detailed summary of uranium biogeochemistry has been written, which enables to restrict the PhD issue to uranium complexation with oxalic acid, a hydrophilic organic acid with good binding properties, ubiquitous in soil waters. Analytical conditions have been established by means of speciation diagrams. The speciation diagrams building by means of literature stability constants has allowed to define the analytical conditions of complex formation. The chosen analytical technique is the hyphenation of a separative technique (liquid chromatography LC or capillary electrophoresis CE) with mass spectrometry (ICPMS). The studied complexes presence in the synthetic samples has been confirmed with UV/visible spectrophotometry. LC-ICPMS analyses have proved the lability of the uranyl-organic acid complexes, namely their tendency to dissociate during analysis, which prevents from studying uranium speciation. CE-ICPMS study of labile complexes from a metal-ligand system has been made possible by employing affinity capillary electrophoresis, which enables to determine stability constants and electrophoretic mobilities. This PhD thesis has allowed to compare the different mathematical treatments of binding isotherm and to take into account ionic strength and real ligand concentration. Affinity CE has been applied successfully to lanthanum-oxalate (model system) and uranium-oxalate systems. The obtained results have been applied to a real system (situated in Le Bouchet). This shows the contribution of the developed method to the modelling of uranium speciation. (author)

  7. Chromosomal Speciation in the Genomics Era: Disentangling Phylogenetic Evolution of Rock-wallabies.

    Science.gov (United States)

    Potter, Sally; Bragg, Jason G; Blom, Mozes P K; Deakin, Janine E; Kirkpatrick, Mark; Eldridge, Mark D B; Moritz, Craig

    2017-01-01

    The association of chromosome rearrangements (CRs) with speciation is well established, and there is a long history of theory and evidence relating to "chromosomal speciation." Genomic sequencing has the potential to provide new insights into how reorganization of genome structure promotes divergence, and in model systems has demonstrated reduced gene flow in rearranged segments. However, there are limits to what we can understand from a small number of model systems, which each only tell us about one episode of chromosomal speciation. Progressing from patterns of association between chromosome (and genic) change, to understanding processes of speciation requires both comparative studies across diverse systems and integration of genome-scale sequence comparisons with other lines of evidence. Here, we showcase a promising example of chromosomal speciation in a non-model organism, the endemic Australian marsupial genus Petrogale . We present initial phylogenetic results from exon-capture that resolve a history of divergence associated with extensive and repeated CRs. Yet it remains challenging to disentangle gene tree heterogeneity caused by recent divergence and gene flow in this and other such recent radiations. We outline a way forward for better integration of comparative genomic sequence data with evidence from molecular cytogenetics, and analyses of shifts in the recombination landscape and potential disruption of meiotic segregation and epigenetic programming. In all likelihood, CRs impact multiple cellular processes and these effects need to be considered together, along with effects of genic divergence. Understanding the effects of CRs together with genic divergence will require development of more integrative theory and inference methods. Together, new data and analysis tools will combine to shed light on long standing questions of how chromosome and genic divergence promote speciation.

  8. Detecting Hidden Diversification Shifts in Models of Trait-Dependent Speciation and Extinction.

    Science.gov (United States)

    Beaulieu, Jeremy M; O'Meara, Brian C

    2016-07-01

    The distribution of diversity can vary considerably from clade to clade. Attempts to understand these patterns often employ state-dependent speciation and extinction models to determine whether the evolution of a particular novel trait has increased speciation rates and/or decreased extinction rates. It is still unclear, however, whether these models are uncovering important drivers of diversification, or whether they are simply pointing to more complex patterns involving many unmeasured and co-distributed factors. Here we describe an extension to the popular state-dependent speciation and extinction models that specifically accounts for the presence of unmeasured factors that could impact diversification rates estimated for the states of any observed trait, addressing at least one major criticism of BiSSE (Binary State Speciation and Extinction) methods. Specifically, our model, which we refer to as HiSSE (Hidden State Speciation and Extinction), assumes that related to each observed state in the model are "hidden" states that exhibit potentially distinct diversification dynamics and transition rates than the observed states in isolation. We also demonstrate how our model can be used as character-independent diversification models that allow for a complex diversification process that is independent of the evolution of a character. Under rigorous simulation tests and when applied to empirical data, we find that HiSSE performs reasonably well, and can at least detect net diversification rate differences between observed and hidden states and detect when diversification rate differences do not correlate with the observed states. We discuss the remaining issues with state-dependent speciation and extinction models in general, and the important ways in which HiSSE provides a more nuanced understanding of trait-dependent diversification. © The Author(s) 2016. Published by Oxford University Press, on behalf of the Society of Systematic Biologists. All rights reserved

  9. Liquid phase microextraction for the analysis of trace elements and their speciation

    International Nuclear Information System (INIS)

    Hu, Bin; He, Man; Chen, Beibei; Xia, Linbo

    2013-01-01

    Trace/ultra-trace elements and their speciation analysis in complex matrices usually require sample preparation procedures to achieve sample clean-up and analyte preconcentration. Sample preparation is often the bottleneck in trace elements and their speciation analysis which has a direct impact on accuracy, precision and limits of detection and is often the rate-determining step of the analytical process. Recent trends in sample preparation include miniaturization, automation, high-throughput performance and reduction in solvent/sample consumption and operation time. Liquid-phase microextraction (LPME) technique as a novel and promising alternative in sample preparation can meet these requirements and has become a very efficient sample preparation technique. This review updates the state of art of LPME for trace elements and their speciation analysis and discusses its promising prospects. The major thrust of the article highlights the applications of LPME including single-drop microextraction (SDME), hollow fiber-liquid phase microextraction (HF-LPME), dispersive liquid liquid microextraction (DLLME) and solidified floating organic drop microextraction (SFODME) to the fields of elemental and their speciation analysis by atomic spectrometry-based methods, especially inductively coupled plasma mass spectrometry. General and specific concepts, different extraction formats and characteristics of LPME are described and compared, along with examples of recent innovations and applications presented to demonstrate its potential for trace elements and their speciation analysis in biological and environmental fields. Moreover, the application potential and an outlook on the combination of LPME and atomic spectrometry-based techniques for inorganic analysis are commentated. - Highlights: • The state of art of LPME for trace elements and their speciation analysis is updated. • Different extraction formats of LPME are described. • The application potential and future

  10. Oxidation state analyses of uranium with emphasis on chemical speciation in geological media

    International Nuclear Information System (INIS)

    Ervanne, H.

    2004-01-01

    This thesis focuses on chemical methods suitable for the determination of uranium redox species in geological materials. Nd-coprecipitation method was studied for the determination of uranium oxidation states in ground waters. This method is ideally suited for the separation of uranium oxidation states in the field, which means that problems associated with the instability of U(IV) during transport are avoided. An alternative method, such as ion exchange, is recommended for the analysis of high saline and calcium- and iron-rich ground waters. U(IV)/Utot was 2.8-7.2% in ground waters in oxidizing conditions and 60-93% in anoxic conditions. From thermodynamic model calculations applied to results from anoxic ground waters it was concluded that uranium can act as redox buffer in granitic ground waters. An ion exchange method was developed for the analysis of uranium oxidation states in different solid materials of geological origin. These included uranium minerals, uraniumbearing minerals, fracture coatings and bulk rock. U(IV)/Utot was 50-70% in uraninites, 5.8-8.7% in secondary uranium minerals, 15-49% in different fracture coatings and 64- 77% in samples from deep bedrock. In the uranium-bearing minerals, U(IV)/Utot was 33-43% (allanites), 5.9% (fergusonite) and 93% (monazite). Although the ion exchange method gave reliable results, there is a risk for the conversion of uranium oxidation states during analysis of heterogeneous samples due to the redox reactions that take place in the presence of some iron compounds. This risk was investigated in a study of several common iron-bearing minerals. The risk for conversion of uranium oxidation states can be screened by sample selection and minimized with use of a redox buffer compound such as polyacrylic acid (PAA). In studies of several carboxylic acids, PAA was found to be the most suitable for extending the application of the method. The stability of uranium oxidation states during analysis and the selectivity

  11. RP-HPLC Method Development and Validation for the Determination and Stability Indicative Studies of Montelukast in Bulk and its Pharmaceutical Formulations

    Directory of Open Access Journals (Sweden)

    A. Patnaik

    2012-01-01

    Full Text Available A simple, precise, accurate, economical and reproducible HPLC method for estimation of montelukast in tablet dosage form has been developed. Quantitative HPLC was performed with Shimadzu LC2010c HT with Winchrom Software with UV-Visible detector (SPD-IOA, PUMP (LC-IOAT and (LC-IOATvp. Phenomenex C8, 5 μm, 25 cm × 4.6 mm i.d. column was used in the study. The mobile phase of ACN: Acetate buffer= 6.5:3.5 of pH 3 were used in this study. The conditions optimized were: flow rate (1 mL/minute, wavelength (222 nm and run time was 20 min. Retention time was found to be 3.08 min. The linearity was found to be in the concentration range of 10-100 μg/mL. The developed method was evaluated in the assay of commercially available tablet moni containing 10 mg of montelukast. The amount of drug in tablet was found to be 10.34 mg/tab for the brand. Results of analysis were validated statistically and by recovery studies. The recovery studies 99.67% was indicative of the accuracy of proposed method. The precision was calculated as repeatability, inter and intraday variation (%RSD for the drug. By using the method, stability of the drug has been studied.

  12. Speciation and Localization of Arsenic in White and Brown Rice Grains

    Energy Technology Data Exchange (ETDEWEB)

    Meharg, Andrew A.; Lombi, Enzo; Williams, Paul N.; Scheckel, Kirk G.; Feldmann, Joerg; Raab, Andrea; Zhu, Yongguan; Islam, Rafiql (EPA); (Bangladesh); (UCopenhagen); (Aberdeen); (Chinese Aca. Sci.)

    2008-06-30

    Synchrotron-based X-ray fluorescence (S-XRF) was utilized to locate arsenic (As) in polished (white) and unpolished (brown) rice grains from the United States, China, and Bangladesh. In white rice As was generally dispersed throughout the grain, the bulk of which constitutes the endosperm. In brown rice As was found to be preferentially localized at the surface, in the region corresponding to the pericarp and aleurone layer. Copper, iron, manganese, and zinc localization followed that of arsenic in brown rice, while the location for cadmium and nickel was distinctly different, showing relatively even distribution throughout the endosperm. The localization of As in the outer grain of brown rice was confirmed by laser ablation ICP?MS. Arsenic speciation of all grains using spatially resolved X-ray absorption near edge structure (?-XANES) and bulk extraction followed by anion exchange HPLC?ICP?MS revealed the presence of mainly inorganic As and dimethylarsinic acid (DMA). However, the two techniques indicated different proportions of inorganic:organic As species. A wider survey of whole grain speciation of white (n = 39) and brown (n = 45) rice samples from numerous sources (field collected, supermarket survey, and pot trials) showed that brown rice had a higher proportion of inorganic arsenic present than white rice. Furthermore, the percentage of DMA present in the grain increased along with total grain arsenic.

  13. Solving mercury (Hg) speciation in soil samples by synchrotron X-ray microspectroscopic techniques.

    Science.gov (United States)

    Terzano, Roberto; Santoro, Anna; Spagnuolo, Matteo; Vekemans, Bart; Medici, Luca; Janssens, Koen; Göttlicher, Jörg; Denecke, Melissa A; Mangold, Stefan; Ruggiero, Pacifico

    2010-08-01

    Direct mercury (Hg) speciation was assessed for soil samples with a Hg concentration ranging from 7 up to 240 mg kg(-1). Hg chemical forms were identified and quantified by sequential extractions and bulk- and micro-analytical techniques exploiting synchrotron generated X-rays. In particular, microspectroscopic techniques such as mu-XRF, mu-XRD and mu-XANES were necessary to solve bulk Hg speciation, in both soil fractions soil samples were metacinnabar (beta-HgS), cinnabar (alpha-HgS), corderoite (Hg(3)S(2)Cl(2)), and an amorphous phase containing Hg bound to chlorine and sulfur. The amount of metacinnabar and amorphous phases increased in the fraction soil components was observed. All the observed Hg-species originated from the slow weathering of an inert Hg-containing waste material (K106, U.S. EPA) dumped in the area several years ago, which is changing into a relatively more dangerous source of pollution. Copyright 2010 Elsevier Ltd. All rights reserved.

  14. Utility of Hantzsch reaction for development of highly sensitive spectrofluorimetric method for determination of alfuzosin and terazosin in bulk, dosage forms and human plasma.

    Science.gov (United States)

    Hammad, Mohamed A; Omar, Mahmoud A; Salman, Baher I

    2017-09-01

    A highly sensitive, cheap, simple and accurate spectrofluorimetric method has been developed and validated for the determination of alfuzosin hydrochloride and terazosin hydrochloride in their pharmaceutical dosage forms and in human plasma. The developed method is based on the reaction of the primary amine moiety in the studied drugs with acetylacetone and formaldehyde according to the Hantzsch reaction, producing yellow fluorescent products that can be measured spectrofluorimetrically at 480 nm after excitation at 415 nm. Different experimental parameters affecting the development and stability of the reaction products were carefully studied and optimized. The fluorescence-concentration plots of alfuzosin and terazosin were rectilinear over a concentration range of 70-900 ng ml -1 , with quantitation limits 27.1 and 32.2 ng ml -1 for alfuzosin and terazosin, respectively. The proposed method was validated according to ICH guidelines and successfully applied to the analysis of the investigated drugs in dosage forms, content uniformity test and spiked human plasma with high accuracy. Copyright © 2017 John Wiley & Sons, Ltd.

  15. Paradigms in isotope dilution mass spectrometry for elemental speciation analysis

    International Nuclear Information System (INIS)

    Meija, Juris; Mester, Zoltan

    2008-01-01

    Isotope dilution mass spectrometry currently stands out as the method providing results with unchallenged precision and accuracy in elemental speciation. However, recent history of isotope dilution mass spectrometry has shown that the extent to which this primary ratio measurement method can deliver accurate results is still subject of active research. In this review, we will summarize the fundamental prerequisites behind isotope dilution mass spectrometry and discuss their practical limits of validity and effects on the accuracy of the obtained results. This review is not to be viewed as a critique of isotope dilution; rather its purpose is to highlight the lesser studied aspects that will ensure and elevate current supremacy of the results obtained from this method

  16. Speciation and zoogeography of amphibian in Sundaland

    Directory of Open Access Journals (Sweden)

    Nia Kurniawan

    2015-12-01

    Full Text Available Sundaland is an interesting area to be explored based on its geological history, topography, and climate. Sundaland consists of Penisular Malaysia, Sumatra, Borneo, and Java which experienced some emergence and submergence process in the past. During 1981-2015, most of research in Sundaland found that amphibian family in Sundaland was dominated by Bufonidae, Ranidae, Microhylidae, Megophrydae, Rachophoridae, and Dicroglossidae which experienced lot of speciation in its history. Among of 4 major islands in Sundaland, Borneo has the highest number of species diversity, then Peninsular Malaysia, Sumatra, and Java. During those years, Sumatra and Java got least concern by researcher. Therefore, it is suggested for further study to explore more in Sumatra and Java. Keywords: Sundaland, amphibian, speciation, zoogeography.

  17. Curing characteristics of flowable and sculptable bulk-fill composites

    OpenAIRE

    Miletic, Vesna; Pongpruenska, Pong; De Munck, Jan; Brooks, Neil R; Van Meerbeek, Bart

    2016-01-01

    OBJECTIVES: The aim of this study was to determine and correlate the degree of conversion (DC) with Vickers hardness (VH) and translucency parameter (TP) with the depth of cure (DoC) of five bulk-fill composites. MATERIALS AND METHODS: Six specimens per group, consisting of Tetric EvoCeram Bulk Fill ("TEC Bulk," Ivoclar Vivadent), SonicFill (Kerr), SDR Smart Dentin Replacement ("SDR," Dentsply), Xenius base ("Xenius," StickTech; commercialized as EverX Posterior, GC), Filtek Bul...

  18. Speciation studies of cobalt in sea water

    International Nuclear Information System (INIS)

    Toteja, R.S.D.; Sudersanan, M.; Iyer, R.K.

    1995-01-01

    Recent results on the speciation of cobalt in simulated and actual sea water is reported using ion exchangers. The influence of magnesium ions in affecting the composition of ion exchangers and subsequent interpretation of the results is discussed. The results indicated that Co +2 may predominate in both the simulated and actual sea water and the presence of other constituents in sea water does not affect the nature of complex species present. (author). 2 refs., 3 tabs., 1 fig

  19. Tungsten Speciation in Firing Range Soils

    Science.gov (United States)

    2011-01-01

    satisfactorily, such as: which tungsten mineral phase is present in soil and to what extent is adsorption important in regu- lating soil solution concentrations... soil solution rather than discrete mineral phases. Information provided in this report will assist the following organizations in future decision...the soil solution ERDC TR-11-1 43 must affect tungsten speciation in other ways. The precipitation of soil minerals also would limit tungsten

  20. Characterization of etch pit formation via the Everson-etching method on CdZnTe crystal surfaces from the bulk to the nanoscale

    International Nuclear Information System (INIS)

    Teague, Lucile C.; Duff, Martine C.; Cadieux, James R.; Soundararajan, Raji; Shick, Charles R.; Lynn, Kelvin G.

    2011-01-01

    A combination of atomic force microscopy, optical microscopy, and mass spectrometry was employed to study CdZnTe crystal surface and used etchant solution following exposure of the CdZnTe crystal to the Everson etch solution. We discuss the results of these studies in relationship to the initial surface preparation methods, the performance of the crystals as radiation spectrometers, the observed etch pit densities, and the chemical mechanism of surface etching. Our results show that the surface features that are exposed to etchants result from interactions with the chemical components of the etchants as well as pre-existing mechanical polishing.

  1. Development and Validation of Stability-Indicating Method for Estimation of Chlorthalidone in Bulk and Tablets with the Use of Experimental Design in Forced Degradation Experiments

    Directory of Open Access Journals (Sweden)

    Sandeep Sonawane

    2016-01-01

    Full Text Available Chlorthalidone was subjected to various forced degradation conditions. Substantial degradation of chlorthalidone was obtained in acid, alkali, and oxidative conditions. Further full factorial experimental design was applied for acid and alkali forced degradation conditions, in which strength of acid/alkali, temperature, and time of heating were considered as independent variables (factors and % degradation was considered as dependent variable (response. Factors responsible for acid and alkali degradation were statistically evaluated using Yates analysis and Pareto chart. Furthermore, using surface response curve, optimized 10% degradation was obtained. All chromatographic separation was carried out on Phenomenex HyperClone C 18 column (250 × 4.6 mm, 5 μ, using mobile phase comprising methanol : acetonitrile : phosphate buffer (20 mM (pH 3.0 adjusted with o-phosphoric acid: 30 : 10 : 60% v/v. The flow rate was kept constant at 1 mL/min and eluent was detected at 241 nm. In calibration curve experiments, linearity was found to be in the range of 2–12 μg/mL. Validation experiments proved good accuracy and precision of the method. Also there was no interference of excipients and degradation products at the retention time of chlorthalidone, indicating specificity of the method.

  2. The genetics of speciation by reinforcement.

    Directory of Open Access Journals (Sweden)

    Daniel Ortiz-Barrientos

    2004-12-01

    Full Text Available Reinforcement occurs when natural selection strengthens behavioral discrimination to prevent costly interspecies matings, such as when matings produce sterile hybrids. This evolutionary process can complete speciation, thereby providing a direct link between Darwin's theory of natural selection and the origin of new species. Here, by examining a case of speciation by reinforcement in Drosophila,we present the first high-resolution genetic study of variation within species for female mating discrimination that is enhanced by natural selection. We show that reinforced mating discrimination is inherited as a dominant trait, exhibits variability within species, and may be influenced by a known set of candidate genes involved in olfaction. Our results show that the genetics of reinforced mating discrimination is different from the genetics of mating discrimination between species, suggesting that overall mating discrimination might be a composite phenomenon, which in Drosophila could involve both auditory and olfactory cues. Examining the genetics of reinforcement provides a unique opportunity for both understanding the origin of new species in the face of gene flow and identifying the genetic basis of adaptive female species preferences, two major gaps in our understanding of speciation.

  3. First passage time to allopatric speciation.

    Science.gov (United States)

    Yamaguchi, Ryo; Iwasa, Yoh

    2013-12-06

    Allopatric speciation is a mechanism to evolve reproductive isolation; it is caused by the accumulation of genetic differences between populations while they are geographically isolated. Here, we studied a simple stochastic model for the time until speciation caused by geographical isolation in fragmented populations that experience recurrent but infrequent migration between subpopulations. We assumed that mating incompatibility is controlled by a number of loci that behave as neutral characters in the accumulation of novel mutations within each population. Genetic distance between populations was defined as the number of incompatibility-controlling loci that differ between them. Genetic distance increases through the separate accumulation of mutations in different populations, but decreases after a successful migration event followed by genetic mixing between migrants and residents. We calculated the time to allopatric speciation, which occurs when the genetic distance exceeds a specified threshold. If the number of invasive individuals relative to the resident population is not very large, diffusion approximation provides an accurate prediction. There is an intermediate optimal rate of migration that maximizes the rate of species creation by recurrent invasion and diversification. We also examined cases that involved more than two populations.

  4. Arsenic speciation and sorption in natural environments

    Science.gov (United States)

    Campbell, Kate M.; Nordstrom, D. Kirk

    2014-01-01

    Aqueous arsenic speciation, or the chemical forms in which arsenic exists in water, is a challenging, interesting, and complicated aspect of environmental arsenic geochemistry. Arsenic has the ability to form a wide range of chemical bonds with carbon, oxygen, hydrogen, and sulfur, resulting in a large variety of compounds that exhibit a host of chemical and biochemical properties. Besides the intriguing chemical diversity, arsenic also has the rare capacity to capture our imaginations in a way that few elements can duplicate: it invokes images of foul play that range from sinister to comedic (e.g., “inheritance powder” and arsenic-spiked elderberry wine). However, the emergence of serious large-scale human health problems from chronic arsenic exposure in drinking water has placed a high priority on understanding environmental arsenic mobility, toxicity, and bioavailability, and chemical speciation is key to these important questions. Ultimately, the purpose of arsenic speciation research is to predict future occurrences, mitigate contamination, and provide successful management of water resources.

  5. High Performance Liquid Chromatographic Method for the Determination of Piroxicam, Naproxen, Diclofenac Sodium, and Mefenamic Acid in Bulk Drug and Pharmaceutical Preparations

    Directory of Open Access Journals (Sweden)

    Sarmad Bahjat Dikran

    2018-03-01

    Full Text Available A simple accurate and rapid reversed phase high performance liquid chromatographic method has been developed and validated for the determination of four nonsteroidal anti-inflammatory drugs;  Piroxicam(PX,  Naproxen(NAP,  Diclofenac sodium(DCL and Mefenamic acid(MFNC in their pure form and different commercial pharmaceutical formulation. The separation was performed on a NUCLEODUR® 100-5 C18ec (250 × 4.6 mm i.d.; particle size 5 μm column as stationary phase with a mobile phase comprising of acetonitrile: deionized water acidified with 1% acetic acid in gradient mode. The flow rate was 1.5 mL.min-1 at the temperature 35 ºC and detection was carried out at 264 nm. Separation has been completed within 8 min. The retention times of Piroxicam, Naproxen, Diclofenac sodium, and Mefenamic acid were 4.267 min, 4.785 min, 6.555 min, and 7.683 min respectively. The linearity for Piroxicam was in the range of 3–200 μg.mL-1 and for Naproxen and Mefenamic acid was in the range 1-200 μg.mL-1, while for Diclofenac sodium was in the range 1.5–200 μg.mL-1. The proposed method was successfully applied for the determination of these drugs in their pure form and different pharmaceutical preparations (tablets, capsules, and ampoule and there is no interference with additives.

  6. Thermodynamics proposes, kinetics decides, speciation dares: speciation of actinides in biological media

    International Nuclear Information System (INIS)

    Ansoborlo, E.

    2005-06-01

    After having recalled the content and purpose of his research thesis, the author proposes a detailed overview of the research works he performed thereafter in the field of the speciation of actinides at the level of the organism entry gates and in target tissues. These works therefore concern four important areas of research in radioprotection: bio-kinetic, toxicology, decorporation, and dosimetry studies. The author outlines how speciation studies can be useful for these different areas, and to better understand and describe, and therefore foresee, the biokinetics and toxicity of radionuclides

  7. Electrospray mass spectrometry for actinides and lanthanide speciation

    International Nuclear Information System (INIS)

    Moulin, C.; Amekraz, B.; Colette, S.; Doizi, D.; Jacopin, C.; Lamouroux, C.; Plancque, G.

    2006-01-01

    Electrospray mass spectrometry (ES-MS) is a new speciation technique that has the great interest to be able to probe the element, the ligand and the complex in order to reach the speciation. This paper will focus on the use of ES-MS for the speciation of actinides/lanthanides on several systems of interest in various fields such as the interaction between DTPA (decorporant) and europium, HEBP and uranium, BTP (new extracting agent) and lanthanides with comparison with known chemistry as well as whenever possible with other speciation techniques

  8. Low Thermal Conductivity of RE-Doped SrO(SrTiO3)1 Ruddlesden Popper Phase Bulk Materials Prepared by Molten Salt Method

    Science.gov (United States)

    Putri, Yulia Eka; Said, Suhana Mohd; Refinel, Refinel; Ohtaki, Michitaka; Syukri, Syukri

    2018-04-01

    The SrO(SrTiO3)1 (Sr2TiO4) Ruddlesden Popper (RP) phase is a natural superlattice comprising of alternately stacking perovskite-type SrTiO3 layers and rock salt SrO layers along the crystallographic c direction. This paper discusses the properties of the Sr2TiO4 and (La, Sm)-doped Sr2TiO4 RP phase synthesized via molten salt method, within the context of thermoelectric applications. A good thermoelectric material requires high electrical conductivity, high Seebeck coefficient and low thermal conductivity. All three conditions have the potential to be fulfilled by the Sr2TiO4 RP phase, in particular, the superlattice structure allows a higher degree of phonon scattering hence resulting in lowered thermal conductivity. In this work, the Sr2TiO4 RP phase is doped with Sm and La respectively, which allows injection of charge carriers, modification of its electronic structure for improvement of the Seebeck coefficient, and most significantly, reduction of thermal conductivity. The particles with submicron size allows excessive phonon scattering along the boundaries, thus reduces the thermal conductivity by fourfold. In particular, the Sm-doped sample exhibited even lower lattice thermal conductivity, which is believed to be due to the mismatch in the ionic radius of Sr and Sm. This finding is useful as a strategy to reduce thermal conductivity of Sr2TiO4 RP phase materials as thermoelectric candidates, by employing dopants of differing ionic radius.

  9. Chromium speciation in solid matrices and regulation: a review

    Energy Technology Data Exchange (ETDEWEB)

    Unceta, N. [University of the Basque Country, Department of Analytical Chemistry, Faculty of Pharmacy, Vitoria-Gasteiz (Spain); Seby, F. [Ultra Traces Analyses Aquitaine (UT2A), Helioparc Pau-Pyrenees, Pau (France); Malherbe, J.; Donard, O.F.X. [Universite de Pau et des Pays de l' Adour, Helioparc Pau-Pyrenees, Laboratoire de Chimie Analytique Bio-Inorganique et Environnement, IPREM, UMR CNRS 5254, Pau (France)

    2010-06-15

    In recent years, the extensive use of chromium in industrial processes has led to the promotion of several directives and recommendations by the European Union, that try to limit and regulate the presence of Cr(VI) in the environment and to protect industrial workers using chromium and end-users of manufactured products. As a consequence, new standard methods and analytical procedures have been published at the EU level for Cr(VI) determination in soil, sludge, sediment, and similar waste materials, workplace atmospheres, cement, packaging materials, industrially produced samples, and corrosion-protection layers on some components of vehicles and electrical and electronic equipment. The objective of this article is to summarize the different directives and recommendations and to critically review the currently existing standard methods and the methods published in the literature for chromium speciation in the above mentioned solid matrices, putting the emphasis on the different extraction procedures which have been developed for each matrix. Particular attention has been paid to Cr(III) and Cr(VI) inter-conversions that can occur during extraction and efforts to minimize these unwanted reactions. Although the use of NaOH-Na{sub 2}CO{sub 3} solutions with hot plate extraction seems to be the more widespread procedure, species transformation can still occur and several studies suggest that speciated isotope-dilution mass spectrometry (SIDMS) could be a suitable tool for correction of these interconversions. Besides, recent studies have proved the role of Cr(III) in chromium toxicology. As a consequence, the authors suggest an update of standard methods in the near future. (orig.)

  10. Calculation and design for SSRF's bulk shield

    Energy Technology Data Exchange (ETDEWEB)

    Fang, K.M. [Shanghai Institute of Applied Physics, Chinese Academy of Science (China)]. E-mail: fangkm@sinap.ac.cn; Xu, X.J. [Shanghai Institute of Applied Physics, Chinese Academy of Science (China); Cai, J.H. [Shanghai Institute of Applied Physics, Chinese Academy of Science (China)

    2006-12-15

    Shielding design objectives for the SSRF are chosen, assumptions for beam loss rates are given, the methods used on the APS by Moe are summarized and introduced to make calculation and design on bulk shield, the factor of skyshine is also considered, design thicknesses for SSRF's bulk shield are presented.

  11. Laser-induced photoacoustic spectroscopy for the speciation of transuranic elements in natural aquatic systems

    International Nuclear Information System (INIS)

    Kim, J.I.; Stumpe, R.; Klenze, R.

    1990-08-01

    Laser-induced Photoacoustic Spectroscopy (LPAS) is a new elegant instrumentation for the chemical speciation of acoustic transuranium (TRU) ions in very dilute concentrations (> 10 -8 mol L -1 ). The paper describes the principle of LPAS and its application to the study of the chemical behaviour of TRU ions in natural aquatic systems, the knowledge of which has become increasingly in demand in connection with the safety analysis of nuclear waste disposal in the geosphere. The first part of the paper describes the principle, instrumentation and characteristics of LPAS in aqueous solution, taking particular examples from our own experience. The theoretical estimation of the speciation sensitivity is demonstrated and the result is compared with experiment. The second part deals with the spectral work in aqueous solution and then with the aplication of LPAS for the speciation of TRU ions in groundwater. Some examples demonstrated are hydrolysis reaction, complexation and colloid generation of the Am 3+ ion. Speciation sensitivities of U, Np, Pu and Am of different oxidation states in a variety of aqueous solutions are summarized. The application is of course open to a broad field of microchemistry in which the conventional spectrophotometric method has difficulty with sensitivity. (orig.)

  12. Laser-induced photoacoustic spectroscopy for the speciation of transuranic elements in natural aquatic systems

    International Nuclear Information System (INIS)

    Kim, J.I.; Stumpe, R.; Klenze, R.

    1991-01-01

    Laser-induced photoacoustic spectroscopy (LPAS) is a new elegant instrumentation for the chemical speciation of aquatic transuranium (TRU) ions in very dilute concentrations (>10 -8 mol L -1 ). The paper describes the principle of LPAS and its application to the study of the chemical behaviour of TRU ions in natural aquatic systems, the knowledge of which has become increasingly in demand in connection with the safety analysis of nuclear waste disposal in the geosphere. The first part of the paper describes the principle, instrumentation and characteristics of LPAS in aqueous solution, taking particular examples from our own experience. The theoretical estimation of the speciation sensitivity is demonstrated and the result is compared with experiment. The second part deals with the spectral work in aqueous solution and then with the application of LPAS for the speciation of TRU ions in groundwater. Some examples demonstrated are hydrolysis reaction, complexation and colloid generation of the Am 3+ ion. Speciation sensitivities of U, Np, Pu and Am of different oxidation states in a variety of aqueous solutions are summarized. The application is of course open to a broad field of microchemistry in which the conventional spectrophotometric method has difficulty with sensitivity

  13. Coupling pervaporation to AAS for inorganic and organic mercury determination. A new approach to speciation of Hg in environmental samples.

    Science.gov (United States)

    Fernandez-Rivas, C; Muñoz-Olivas, R; Camara, C

    2001-12-01

    The design and development of a new approach for Hg speciation in environmental samples is described in detail. This method, consisting of the coupling of pervaporation and atomic absorption spectrometry, is based on a membrane phenomenon that combines the evaporation of volatile analytes and their diffusion through a polymeric membrane. It is proposed here as an alternative to gas chromatography for speciation of inorganic and organic Hg compounds, as the latter compounds are volatile and can be separated by applying the principles mentioned above. The interest of this method lies in its easy handling, low cost, and rapidity for the analysis of liquid and solid samples. This method has been applied to Hg speciation in a compost sample provided by a waste water treatment plant.

  14. Speciation of organic aerosols in the Saharan Air Layer and in the free troposphere westerlies

    Directory of Open Access Journals (Sweden)

    M. I. García

    2017-07-01

    Full Text Available We focused this research on the composition of the organic aerosols transported in the two main airflows of the subtropical North Atlantic free troposphere: (i the Saharan Air Layer – the warm, dry and dusty airstream that expands from North Africa to the Americas at subtropical and tropical latitudes – and (ii the westerlies, which flow from North America over the North Atlantic at mid- and subtropical latitudes. We determined the inorganic compounds (secondary inorganic species and elemental composition, elemental carbon and the organic fraction (bulk organic carbon and organic speciation present in the aerosol collected at Izaña Observatory,  ∼  2400 m a.s.l. on the island of Tenerife. The concentrations of all inorganic and almost all organic compounds were higher in the Saharan Air Layer than in the westerlies, with bulk organic matter concentrations within the range 0.02–4.0 µg m−3. In the Saharan Air Layer, the total aerosol population was by far dominated by dust (93 % of bulk mass, which was mixed with secondary inorganic pollutants ( <  5 % and organic matter ( ∼  1.5 %. The chemical speciation of the organic aerosols (levoglucosan, dicarboxylic acids, saccharides, n-alkanes, hopanes, polycyclic aromatic hydrocarbons and those formed after oxidation of α-pinene and isoprene, determined by gas chromatography coupled with mass spectrometry accounted for 15 % of the bulk organic matter (determined by the thermo-optical transmission technique; the most abundant organic compounds were saccharides (associated with surface soils, secondary organic aerosols linked to oxidation of biogenic isoprene (SOA ISO and dicarboxylic acids (linked to several primary sources and SOA. When the Saharan Air Layer shifted southward, Izaña was within the westerlies stream and organic matter accounted for  ∼  28 % of the bulk mass of aerosols. In the westerlies, the organic aerosol species determined

  15. Mining the bulk positron lifetime

    International Nuclear Information System (INIS)

    Aourag, H.; Guittom, A.

    2009-01-01

    We introduce a new approach to investigate the bulk positron lifetimes of new systems based on data-mining techniques. Through data mining of bulk positron lifetimes, we demonstrate the ability to predict the positron lifetimes of new semiconductors on the basis of available semiconductor data already studied. Informatics techniques have been applied to bulk positron lifetimes for different tetrahedrally bounded semiconductors in order to discover computational design rules. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  16. Some actinide speciation using laser induced photoacoustic spectroscopy

    International Nuclear Information System (INIS)

    Pollard, P.M.; McMillan, J.W.; Phillips, G.; Thomason, H.P.; Ewart, F.T.

    1988-01-01

    Laser induced photoacoustic spectroscopy is an attractive method for the speciation of actinides in solutions from nuclear disposal studies because it is essentially non-invasive and has a reasonably high sensitivity, down to ca 10 -8 M. A novel true dual beam system has been constructed and commissioned at Harwell with a performance at least equal to any others in existence. It is based on a XeCl excimer laser and a dye laser, beam splitter, two laser power monitors and photoacoustic cells. The wavelength scanning, data collection, and spectra processing and display are controlled by an Apricot computer. The sample and reference cells are housed in an inert atmosphere glove box. Early applications of the equipment described include measurements of Am and Np species under varying conditions of pH, Eh and carbonate concentration. The observations show some correlation with predictions made using the geochemical modelling code PHREEQE. (orig.)

  17. Arsenic speciation in solids using X-ray absorption spectroscopy

    Science.gov (United States)

    Foster, Andrea L.; Kim, Chris S.

    2014-01-01

    Synchrotron-based X-ray absorption spectroscopy (XAS) is an in situ, minimally-destructive, element-specific, molecular-scale structural probe that has been employed to study the chemical forms (species) of arsenic (As) in solid and aqueous phases (including rocks, soils, sediment, synthetic compounds, and numerous types of biota including humans) for more than 20 years. Although several excellent reviews of As geochemistry and As speciation in the environment have been published previously (including recent contributions in this volume), the explosion of As-XAS studies over the past decade (especially studies employing microfocused X-ray beams) warrants this new review of the literature and of data analysis methods.

  18. Hexaferrite multiferroics: from bulk to thick films

    Science.gov (United States)

    Koutzarova, T.; Ghelev, Ch; Peneva, P.; Georgieva, B.; Kolev, S.; Vertruyen, B.; Closset, R.

    2018-03-01

    We report studies of the structural and microstructural properties of Sr3Co2Fe24O41 in bulk form and as thick films. The precursor powders for the bulk form were prepared following the sol-gel auto-combustion method. The prepared pellets were synthesized at 1200 °C to produce Sr3Co2Fe24O41. The XRD spectra of the bulks showed the characteristic peaks corresponding to the Z-type hexaferrite structure as a main phase and second phases of CoFe2O4 and Sr3Fe2O7-x. The microstructure analysis of the cross-section of the bulk pellets revealed a hexagonal sheet structure. Large areas were observed of packages of hexagonal sheets where the separate hexagonal particles were ordered along the c axis. Sr3Co2Fe24O41 thick films were deposited from a suspension containing the Sr3Co2Fe24O41 powder. The microstructural analysis of the thick films showed that the particles had the perfect hexagonal shape typical for hexaferrites.

  19. Measurement method of moving vehicle in the magnetic levitation and propulsion system using high-Tc superconducting bulks; Koon chodendo barukutai wo riyoshita fujo suishin shisutemu no suishin tokusei keisoku shuho

    Energy Technology Data Exchange (ETDEWEB)

    Fuwa, Y.; Mizuma, T.

    1999-06-07

    The transportation system using simple magnetic levitation system got in the combination of high-temperature superconductivity bulk body and permanent magnet, which caught a quantum magnetic flux, is devised in great numbers, and the model equipment has also been manufactured. In the meantime, a grasp of levitation and guide characteristics is necessary for the case in which this levitation system is applied to the simple individual transportation system, and the measurement of the levitation characteristics is indispensable for the reason. In the conventional research, the measurement of the levitation characteristics has not been very much made. There was due to be no technique which measured kinetic characteristics of noncontacting surfacing and running travel body. In this study, measuring method for measuring these levitation characteristics was devised, and it was applied to actual measurement by the production of the model test equipment. Through this measurement, the purpose of this study is to show with that it is applicable for the real test equipment as this measuring method judges possibility of application to simple transportation system. (NEDO)

  20. Plutonium Speciation, Solubilization and Migration in Soils

    International Nuclear Information System (INIS)

    Neu, M.; Runde, W.

    1999-01-01

    This report summarizes research completed in the first half of a three-year project. As outlined in the authors' proposal they are focusing on (1) characterizing the plutonium at an actinide contaminated site, RFETS, including determining the origin, dispersion, and speciation of the plutonium, (2) studying environmentally important plutonium complexes, primarily hydroxides and carbonates, and (3) examining the interactions of plutonium species with manganese minerals. In the first year the authors focused on site based studies. This year they continue to characterize samples from the RFETS, study the formation and structural and spectroscopic features of environmentally relevant Pu species, and begin modeling the environmental behavior of plutonium

  1. Speciation of arsenic in biological samples.

    Science.gov (United States)

    Mandal, Badal Kumar; Ogra, Yasumitsu; Anzai, Kazunori; Suzuki, Kazuo T

    2004-08-01

    Speciation of arsenicals in biological samples is an essential tool to gain insight into its distribution in tissues and its species-specific toxicity to target organs. Biological samples (urine, hair, fingernail) examined in the present study were collected from 41 people of West Bengal, India, who were drinking arsenic (As)-contaminated water, whereas 25 blood and urine samples were collected from a population who stopped drinking As contaminated water 2 years before the blood collection. Speciation of arsenicals in urine, water-methanol extract of freeze-dried red blood cells (RBCs), trichloroacetic acid treated plasma, and water extract of hair and fingernail was carried out by high-performance liquid chromatography (HPLC)-inductively coupled argon plasma mass spectrometry (ICP MS). Urine contained arsenobetaine (AsB, 1.0%), arsenite (iAs(III), 11.3), arsenate (iAs(V), 10.1), monomethylarsonous acid (MMA(III), 6.6), monomethylarsonic acid (MMA(V), 10.5), dimethylarsinous acid (DMA(III), 13.0), and dimethylarsinic acid (DMA(V), 47.5); fingernail contained iAs(III) (62.4%), iAs(V) (20.2), MMA(V) (5.7), DMA(III) (8.9), and DMA(V) (2.8); hair contained iAs(III) (58.9%), iAs(V) (34.8), MMA(V) (2.9), and DMA(V) (3.4); RBCs contained AsB (22.5%) and DMA(V) (77.5); and blood plasma contained AsB (16.7%), iAs(III) (21.1), MMA(V) (27.1), and DMA(V) (35.1). MMA(III), DMA(III), and iAs(V) were not found in any plasma and RBCs samples, but urine contained all of them. Arsenic in urine, fingernails, and hair are positively correlated with water As, suggesting that any of these measurements could be considered as a biomarker to As exposure. Status of urine and exogenous contamination of hair urgently need speciation of As in these samples, but speciation of As in nail is related to its total As (tAs) concentration. Therefore, total As concentrations of nails could be considered as biomarker to As exposure in the endemic areas.

  2. Speciation of arsenic in biological samples

    International Nuclear Information System (INIS)

    Mandal, Badal Kumar; Ogra, Yasumitsu; Anzai, Kazunori; Suzuki, Kazuo T.

    2004-01-01

    Speciation of arsenicals in biological samples is an essential tool to gain insight into its distribution in tissues and its species-specific toxicity to target organs. Biological samples (urine, hair, fingernail) examined in the present study were collected from 41 people of West Bengal, India, who were drinking arsenic (As)-contaminated water, whereas 25 blood and urine samples were collected from a population who stopped drinking As contaminated water 2 years before the blood collection. Speciation of arsenicals in urine, water-methanol extract of freeze-dried red blood cells (RBCs), trichloroacetic acid treated plasma, and water extract of hair and fingernail was carried out by high-performance liquid chromatography (HPLC)-inductively coupled argon plasma mass spectrometry (ICP MS). Urine contained arsenobetaine (AsB, 1.0%), arsenite (iAs III , 11.3), arsenate (iAs V , 10.1), monomethylarsonous acid (MMA III , 6.6), monomethylarsonic acid (MMA V , 10.5), dimethylarsinous acid (DMA III , 13.0), and dimethylarsinic acid (DMA V , 47.5); fingernail contained iAs III (62.4%), iAs V (20.2), MMA V (5.7), DMA III (8.9), and DMA V (2.8); hair contained iAs III (58.9%), iAs V (34.8), MMA V (2.9), and DMA V (3.4); RBCs contained AsB (22.5%) and DMA V (77.5); and blood plasma contained AsB (16.7%), iAs III (21.1), MMA V (27.1), and DMA V (35.1). MMA III , DMA III , and iAs V were not found in any plasma and RBCs samples, but urine contained all of them. Arsenic in urine, fingernails, and hair are positively correlated with water As, suggesting that any of these measurements could be considered as a biomarker to As exposure. Status of urine and exogenous contamination of hair urgently need speciation of As in these samples, but speciation of As in nail is related to its total As (tAs) concentration. Therefore, total As concentrations of nails could be considered as biomarker to As exposure in the endemic areas

  3. Nanopatterned Bulk Metallic Glass Biosensors.

    Science.gov (United States)

    Kinser, Emily R; Padmanabhan, Jagannath; Yu, Roy; Corona, Sydney L; Li, Jinyang; Vaddiraju, Sagar; Legassey, Allen; Loye, Ayomiposi; Balestrini, Jenna; Solly, Dawson A; Schroers, Jan; Taylor, André D; Papadimitrakopoulos, Fotios; Herzog, Raimund I; Kyriakides, Themis R

    2017-12-22

    Nanopatterning as a surface area enhancement method has the potential to increase signal and sensitivity of biosensors. Platinum-based bulk metallic glass (Pt-BMG) is a biocompatible material with electrical properties conducive for biosensor electrode applications, which can be processed in air at comparably low temperatures to produce nonrandom topography at the nanoscale. Work presented here employs nanopatterned Pt-BMG electrodes functionalized with glucose oxidase enzyme to explore the impact of nonrandom and highly reproducible nanoscale surface area enhancement on glucose biosensor performance. Electrochemical measurements including cyclic voltammetry (CV) and amperometric voltammetry (AV) were completed to compare the performance of 200 nm Pt-BMG electrodes vs Flat Pt-BMG control electrodes. Glucose dosing response was studied in a range of 2 mM to 10 mM. Effective current density dynamic range for the 200 nm Pt-BMG was 10-12 times greater than that of the Flat BMG control. Nanopatterned electrode sensitivity was measured to be 3.28 μA/cm 2 /mM, which was also an order of magnitude greater than the flat electrode. These results suggest that nonrandom nanotopography is a scalable and customizable engineering tool which can be integrated with Pt-BMGs to produce biocompatible biosensors with enhanced signal and sensitivity.

  4. Dynamic speciation analysis and bioavailability of metals in aquatic systems

    NARCIS (Netherlands)

    Leeuwen, van H.P.; Town, R.M.; Buffle, J.; Cleven, R.F.M.J.; Davison, W.; Puy, J.; Riemsdijk, van W.H.; Sigg, L.

    2005-01-01

    Dynamic metal speciation analysis in aquatic ecosystems is emerging as a powerful basis for development of predictions of bioavailability and reliable risk assessment strategies. A given speciation sensor is characterized by an effective time scale or kinetic window that defines the measurable metal

  5. Parasites Promote and When Might They Constrain Ecological Speciation?

    Directory of Open Access Journals (Sweden)

    Anssi Karvonen

    2012-01-01

    Full Text Available Research on speciation and adaptive radiation has flourished during the past decades, yet factors underlying initiation of reproductive isolation often remain unknown. Parasites represent important selective agents and have received renewed attention in speciation research. We review the literature on parasite-mediated divergent selection in context of ecological speciation and present empirical evidence for three nonexclusive mechanisms by which parasites might facilitate speciation: reduced viability or fecundity of immigrants and hybrids, assortative mating as a pleiotropic by-product of host adaptation, and ecologically-based sexual selection. We emphasise the lack of research on speciation continuums, which is why no study has yet made a convincing case for parasite driven divergent evolution to initiate the emergence of reproductive isolation. We also point interest towards selection imposed by single versus multiple parasite species, conceptually linking this to strength and multifariousness of selection. Moreover, we discuss how parasites, by manipulating behaviour or impairing sensory abilities of hosts, may change the form of selection that underlies speciation. We conclude that future studies should consider host populations at variable stages of the speciation process, and explore recurrent patterns of parasitism and resistance that could pinpoint the role of parasites in imposing the divergent selection that initiates ecological speciation.

  6. Self-consistent approach for neutral community models with speciation

    NARCIS (Netherlands)

    Haegeman, Bart; Etienne, Rampal S.

    Hubbell's neutral model provides a rich theoretical framework to study ecological communities. By incorporating both ecological and evolutionary time scales, it allows us to investigate how communities are shaped by speciation processes. The speciation model in the basic neutral model is

  7. The neutral theory of biodiversity with random fission speciation

    NARCIS (Netherlands)

    Etienne, Rampal S.; Haegeman, Bart

    The neutral theory of biodiversity and biogeography emphasizes the importance of dispersal and speciation to macro-ecological diversity patterns. While the influence of dispersal has been studied quite extensively, the effect of speciation has not received much attention, even though it was already

  8. What do we need to know about speciation?

    NARCIS (Netherlands)

    Butlin, Roger; Debelle, Allan; Kerth, Claudius; Snook, Rhonda R.; Beukeboom, Leo W.; Castillo Cajas, Ruth; Diao, Wenwen; Maan, Martine E.; Paolucci, Silvia; Weissing, Franz J.; van de Zande, Louis; Hoikkala, Anneli; Geuverink, Elzemiek; Jennings, Jackson; Kankare, Maaria; Knott, K. Emily; Tyukmaeva, Venera I.; Zoumadakis, Christos; Ritchie, Michael G.; Barker, Daniel; Immonen, Elina; Kirkpatrick, Mark; Noor, Mohamed; Macias Garcia, Constantino; Schmitt, Thomas; Schilthuizen, Menno

    Speciation has been a major focus of evolutionary biology research in recent years, with many important advances. However, some of the traditional organising principles of the subject area no longer provide a satisfactory framework, such as the classification of speciation mechanisms by geographical

  9. Speciation imperatives for waste management and environmental pollution

    International Nuclear Information System (INIS)

    Wymer, R.G.

    2001-01-01

    This paper addresses speciation requirements in the context of problems produced by nuclear energy and nuclear weapons production. These problems are primarily in the areas of waste management, material contamination, and environmental pollution. They pose difficult and important measurement and speciation challenges. Examples of speciation requirements in the context of national and international regulations are presented to exemplify and make quantitative the types of problems posed by waste management, material contamination, and environmental pollution. The importance of identifying species present in the natural environment as well as in wastes from chemical and physical processing and from waste management activities and accidental releases is addressed. Differing speciation requirements for macro and micro concentrations of species are discussed. The role of speciation in modelling studies is discussed. (author)

  10. Integration of bulk piezoelectric materials into microsystems

    Science.gov (United States)

    Aktakka, Ethem Erkan

    Bulk piezoelectric ceramics, compared to deposited piezoelectric thin-films, provide greater electromechanical coupling and charge capacity, which are highly desirable in many MEMS applications. In this thesis, a technology platform is developed for wafer-level integration of bulk piezoelectric substrates on silicon, with a final film thickness of 5-100microm. The characterized processes include reliable low-temperature (200°C) AuIn diffusion bonding and parylene bonding of bulk-PZT on silicon, wafer-level lapping of bulk-PZT with high-uniformity (+/-0.5microm), and low-damage micro-machining of PZT films via dicing-saw patterning, laser ablation, and wet-etching. Preservation of ferroelectric and piezoelectric properties is confirmed with hysteresis and piezo-response measurements. The introduced technology offers higher material quality and unique advantages in fabrication flexibility over existing piezoelectric film deposition methods. In order to confirm the preserved bulk properties in the final film, diaphragm and cantilever beam actuators operating in the transverse-mode are designed, fabricated and tested. The diaphragm structure and electrode shapes/sizes are optimized for maximum deflection through finite-element simulations. During tests of fabricated devices, greater than 12microm PP displacement is obtained by actuation of a 1mm2 diaphragm at 111kHz with integration of a 50-80% efficient power management IC, which incorporates a supply-independent bias circuitry, an active diode for low-dropout rectification, a bias-flip system for higher efficiency, and a trickle battery charger. The overall system does not require a pre-charged battery, and has power consumption of <1microW in active-mode (measured) and <5pA in sleep-mode (simulated). Under lg vibration at 155Hz, a 70mF ultra-capacitor is charged from OV to 1.85V in 50 minutes.

  11. The rate test of speciation: estimating the likelihood of non-allopatric speciation from reproductive isolation rates in Drosophila.

    Science.gov (United States)

    Yukilevich, Roman

    2014-04-01

    Among the most debated subjects in speciation is the question of its mode. Although allopatric (geographical) speciation is assumed the null model, the importance of parapatric and sympatric speciation is extremely difficult to assess and remains controversial. Here I develop a novel approach to distinguish these modes of speciation by studying the evolution of reproductive isolation (RI) among taxa. I focus on the Drosophila genus, for which measures of RI are known. First, I incorporate RI into age-range correlations. Plots show that almost all cases of weak RI are between allopatric taxa whereas sympatric taxa have strong RI. This either implies that most reproductive isolation (RI) was initiated in allopatry or that RI evolves too rapidly in sympatry to be captured at incipient stages. To distinguish between these explanations, I develop a new "rate test of speciation" that estimates the likelihood of non-allopatric speciation given the distribution of RI rates in allopatry versus sympatry. Most sympatric taxa were found to have likely initiated RI in allopatry. However, two putative candidate species pairs for non-allopatric speciation were identified (5% of known Drosophila). In total, this study shows how using RI measures can greatly inform us about the geographical mode of speciation in nature. © 2013 The Author(s). Evolution © 2013 The Society for the Study of Evolution.

  12. Uranium(VI) speciation by spectroscopy

    International Nuclear Information System (INIS)

    Meinrath, G.

    1997-01-01

    The application of UV-Vis and time-resolved laser-induced fluorescence (TRLF) spectroscopies to direct of uranium(VI) in environmental samples offers various prospects that have, however, serious limitations. While UV-Vis spectroscopy is probably not sensitive enough to detect uranium(VI) species in the majority of environmental samples, TRLFS is principially able to speciate uranium(VI) at very low concentration levels in the nanomol range. Speciation by TRLFS can be based on three parameters: excitation spectrum, emission spectrum and lifetime of the fluorescence emission process. Due to quenching effects, the lifetime may not be expected to be as characteristics as, e.g., the emission spectrum. Quenching of U(VI) fluorescence by reaction with organic substances, inorganic ions and formation of carbonate radicals is one important limiting factor in the application of U(VI) fluorescence spectroscopy. Fundamental photophysical criteria are illustrated using UV-Vis and fluorescence spectra of U(VI) hydrolysis and carbonato species as examples. (author)

  13. Chromium fractionation and speciation in natural waters.

    Science.gov (United States)

    Pereira, Catarinie Diniz; Techy, João Gabriel; Ganzarolli, Edgard Moreira; Quináia, Sueli Pércio

    2012-05-01

    It is common for leather industries to dump chromium-contaminated effluent into rivers and other bodies of water. Thus, it is crucial to know the impacts caused by this practice to the environment. A study on chromium partitioning and speciation, with determination at trace levels, was carried out in a potentially contaminated creek. Chromium fractionation and speciation was performed using a flow-injection preconcentration system and detection by flame atomic absorption spectrometry. High levels of this element were found in the particulate material (449-9320 mg kg(-1)), which indicates its compatibility with this fraction. The concentration of Cr(iii) in the water samples collected ranged from 5.2-105.2 μg L(-1). Cr(vi) was always below of the DL (0.3 μg L(-1)). Chromium accumulation observed in the sediment (873-1691 mg kg(-1)) may confirm contamination due to the long term release of contaminated effluents in the creek.

  14. Sodium Flux Growth of Bulk Gallium Nitride

    Science.gov (United States)

    Von Dollen, Paul Martin

    This dissertation focused on development of a novel apparatus and techniques for crystal growth of bulk gallium nitride (GaN) using the sodium flux method. Though several methods exist to produce bulk GaN, none have been commercialized on an industrial scale. The sodium flux method offers potentially lower cost production due to relatively mild process conditions while maintaining high crystal quality. But the current equipment and methods for sodium flux growth of bulk GaN are generally not amenable to large-scale crystal growth or in situ investigation of growth processes, which has hampered progress. A key task was to prevent sodium loss or migration from the sodium-gallium growth melt while permitting N2 gas to access the growing crystal, which was accomplished by implementing a reflux condensing stem along with a reusable sealed capsule. The reflux condensing stem also enabled direct monitoring and control of the melt temperature, which has not been previously reported for the sodium flux method. Molybdenum-based materials were identified from a corrosion study as candidates for direct containment of the corrosive sodium-gallium melt. Successful introduction of these materials allowed implementation of a crucible-free containment system, which improved process control and can potentially reduce crystal impurity levels. Using the new growth system, the (0001) Ga face (+c plane) growth rate was >50 mum/hr, which is the highest bulk GaN growth rate reported for the sodium flux method. Omega X-ray rocking curve (?-XRC) measurements indicated the presence of multiple grains, though full width at half maximum (FWHM) values for individual peaks were 1020 atoms/cm3, possibly due to reactor cleaning and handling procedures. This dissertation also introduced an in situ technique to correlate changes in N2 pressure with dissolution of nitrogen and precipitation of GaN from the sodium-gallium melt. Different stages of N2 pressure decay were identified and linked to

  15. Modelling of bulk superconductor magnetization

    International Nuclear Information System (INIS)

    Ainslie, M D; Fujishiro, H

    2015-01-01

    This paper presents a topical review of the current state of the art in modelling the magnetization of bulk superconductors, including both (RE)BCO (where RE = rare earth or Y) and MgB 2 materials. Such modelling is a powerful tool to understand the physical mechanisms of their magnetization, to assist in interpretation of experimental results, and to predict the performance of practical bulk superconductor-based devices, which is particularly important as many superconducting applications head towards the commercialization stage of their development in the coming years. In addition to the analytical and numerical techniques currently used by researchers for modelling such materials, the commonly used practical techniques to magnetize bulk superconductors are summarized with a particular focus on pulsed field magnetization (PFM), which is promising as a compact, mobile and relatively inexpensive magnetizing technique. A number of numerical models developed to analyse the issues related to PFM and optimise the technique are described in detail, including understanding the dynamics of the magnetic flux penetration and the influence of material inhomogeneities, thermal properties, pulse duration, magnitude and shape, and the shape of the magnetization coil(s). The effect of externally applied magnetic fields in different configurations on the attenuation of the trapped field is also discussed. A number of novel and hybrid bulk superconductor structures are described, including improved thermal conductivity structures and ferromagnet–superconductor structures, which have been designed to overcome some of the issues related to bulk superconductors and their magnetization and enhance the intrinsic properties of bulk superconductors acting as trapped field magnets. Finally, the use of hollow bulk cylinders/tubes for shielding is analysed. (topical review)

  16. Speciation of chromium, copper, iron, manganese, nickel, and zinc of sediment from the Densu River by sequential extraction

    International Nuclear Information System (INIS)

    Carboo, D.; Brimah, A.K.; Debrah, C.

    1999-04-01

    Total concentrations of the broad metal spectrum and speciation of Cr, Cu, Fe, Ni, Mn and Zn in sediments of River Densu are studied in order to establish the extent of pollution and their capacity of remobilization. Eight composite samples were analyzed, major components of the sediments were studied using Instrumental Neutron Activation Analysis (INAA) and Atomic Absorption Spectrophotometer (AAS). From the results obtained, it can be concluded that the sediment has Cd value above the normal range. The distribution of the elements in various fractions depends largely on the element. Most of the elements have the bulk of their concentration in the residual fraction. (author)

  17. The Development of Molybdenum Speciation as a Paleoredox Tool

    Science.gov (United States)

    Rodley, J.; Peacock, C.; Mosselmans, J. F. W.; Poulton, S.

    2017-12-01

    The redox state of the oceans has changed throughout geological time and an understanding of these changes is essential to elucidate links between ocean chemistry, climate and life. Due to its abundance in seawater and redox-sensitive nature, molybdenum has enormous potential as a paleoredox proxy. Although a significant amount of research has been done on molybdenum in ancient and modern sediments in terms of its concentrations and isotopic ratios there remains a limited understanding of the drawdown mechanisms of molybdenum under different redox conditions restricting its use in identifying a range of redox states. In order to address these uncertainties, we have developed a novel sequential extraction technique to examine molybdenum concentrations in six sediment fractions from modern samples that represent oxic, nitrogenous, ferruginous and euxinic environments. In addition we use µ-XRF and µ-XANES synchrotron spectroscopy to examine the molybdenum speciation within these fractions and environments. To interpret our µ-XANES data we have developed an extensive library of molybdenum XANES standards that represent molybdenum sequestration by the sediment fractions identified from the sequential extraction. To further verify our synchrotron results we developed a series of µ-XANES micro-column experiments to examine preferential uptake pathways of molybdenum to different sediment phases under a euxinic water column. The initial data from both the sequential extraction and µ-XANES methods indicate that molybdenum is not limited to a single burial pathway in any of the redox environments. We find that each of the redox environments can be characterised by a limited set of molybdenum phase associations, with molybdenum adsorption to pyrite likely the dominant burial pathway. These findings agree with existing research for molybdenum speciation in euxinic environments suggesting that both pyrite and sulphidised organic matter act as important molybdenum sinks. Our

  18. Method and Apparatus of Measuring Velocity and Sound Attenuation Coefficient in Bulk Materials Based on the Analysis of the Structure of Sound-Insulation Materials on the Basis of Perlite

    Science.gov (United States)

    Kapranov, B. I.; Mashanov, A. P.

    2017-04-01

    This paper presents the results of research and describes the apparatus for measuring the acoustic characteristics of bulk materials. Ultrasound, it has passed through a layer of bulk material, is further passes through an air gap. The presence of air gap prevents from measuring tract mechanical contacts, but complicates the measurement technology Studies were conducted on the example of measuring the acoustic characteristics of the widely used perlite-based sound-proofing material.

  19. Can groundwater be successfully implemented as a bulk water ...

    African Journals Online (AJOL)

    that groundwater can be developed as a potential viable bulk-water supply source. This paper attempts .... fracturing, even when using conventional geophysical methods. Gneiss and/or ..... will start to be self-sufficient in about 2018 and 2019.

  20. Bulk metallic glass for low noise fluxgate, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The team of Prime Photonics, Virginia Tech, and Utron Kinetics propose to demonstrate a method for fabrication of a bulk, amorphous, cobalt-rich material that...

  1. Renormalization group approach to causal bulk viscous cosmological models

    International Nuclear Information System (INIS)

    Belinchon, J A; Harko, T; Mak, M K

    2002-01-01

    The renormalization group method is applied to the study of homogeneous and flat Friedmann-Robertson-Walker type universes, filled with a causal bulk viscous cosmological fluid. The starting point of the study is the consideration of the scaling properties of the gravitational field equations, the causal evolution equation of the bulk viscous pressure and the equations of state. The requirement of scale invariance imposes strong constraints on the temporal evolution of the bulk viscosity coefficient, temperature and relaxation time, thus leading to the possibility of obtaining the bulk viscosity coefficient-energy density dependence. For a cosmological model with bulk viscosity coefficient proportional to the Hubble parameter, we perform the analysis of the renormalization group flow around the scale-invariant fixed point, thereby obtaining the long-time behaviour of the scale factor

  2. EPA’s SPECIATE 4.4 Database:Development and Uses

    Science.gov (United States)

    SPECIATE is the U.S. Environmental Protection Agency's (EPA)repository of volatile organic gas and particulate matter (PM) speciation profiles for air pollution sources. EPA released SPECIATE 4.4 in early 2014 and, in total, the SPECIATE 4.4 database includes 5,728 PM, VOC, total...

  3. Kinetic speciation and bioavailability of copper and nickel in mangrove sediments

    Digital Repository Service at National Institute of Oceanography (India)

    Chakraborty, P.; Chakraborty, S.; Ramteke, D.; Chennuri, K.

    speciation (and dynamic/labile complexes) of metals in soils and sediments. The approaches include batch techniques (Beauchemin et al., 2002; Bermond and Varrault, 2004; Yu and Klarup, 1994), flow techniques (Beauchemin et al., 2002; Shiowatana et al... and mobility of metal and its migration in a polluted or naturally contaminated soils/sediments (Beauchemin et al., 2002; Bermond and Varrault, 2004; Fangueiro et al., 2002). This method is capable of determining kinetically distinguishable metal complexes...

  4. Induction detection of concealed bulk banknotes

    International Nuclear Information System (INIS)

    Fuller, Christopher; Chen, Antao

    2011-01-01

    Bulk cash smuggling is a serious issue that has grown in volume in recent years. By building on the magnetic characteristics of paper currency, induction sensing is found to be capable of quickly detecting large masses of banknotes. The results show that this method is effective in detecting bulk cash through concealing materials such as plastics, cardboards, fabrics and aluminum foil. The significant difference in the observed phase between the received signals caused by conducting materials and ferrite compounds, found in banknotes, provides a good indication that this process can overcome the interference by metal objects in a real sensing application. This identification strategy has the potential to not only detect the presence of banknotes, but also the number, while still eliminating false positives caused by metal objects

  5. Induction detection of concealed bulk banknotes

    Science.gov (United States)

    Fuller, Christopher; Chen, Antao

    2012-06-01

    The smuggling of bulk cash across borders is a serious issue that has increased in recent years. In an effort to curb the illegal transport of large numbers of paper bills, a detection scheme has been developed, based on the magnetic characteristics of bank notes. The results show that volumes of paper currency can be detected through common concealing materials such as plastics, cardboard, and fabrics making it a possible potential addition to border security methods. The detection scheme holds the potential of also reducing or eliminating false positives caused by metallic materials found in the vicinity, by observing the stark difference in received signals caused by metal and currency. The detection scheme holds the potential to detect for both the presence and number of concealed bulk notes, while maintaining the ability to reduce false positives caused by metal objects.

  6. Sexual selection and magic traits in speciation with gene flow

    Directory of Open Access Journals (Sweden)

    Maria R. SERVEDIO, Michael KOPP

    2012-06-01

    Full Text Available The extent to which sexual selection is involved in speciation with gene flow remains an open question and the subject of much research. Here, we propose that some insight can be gained from considering the concept of magic traits (i.e., traits involved in both reproductive isolation and ecological divergence. Both magic traits and other, “non-magic”, traits can contribute to speciation via a number of specific mechanisms. We argue that many of these mechanisms are likely to differ widely in the extent to which they involve sexual selection. Furthermore, in some cases where sexual selection is present, it may be prone to inhibit rather than drive speciation. Finally, there are a priori reasons to believe that certain categories of traits are much more effective than others in driving speciation. The combination of these points suggests a classification of traits that may shed light on the broader role of sexual selection in speciation with gene flow. In particular, we suggest that sexual selection can act as a driver of speciation in some scenarios, but may play a negligible role in potentially common categories of magic traits, and may be likely to inhibit speciation in common categories of non-magic traits [Current Zoology 58 (3: 507–513, 2012].

  7. Bulk viscosity and cosmological evolution

    International Nuclear Information System (INIS)

    Beesham, A.

    1996-01-01

    In a recent interesting paper, Pimentel and Diaz-Rivera (Nuovo Cimento B, 109(1994) 1317) have derived several solutions with bulk viscosity in homogeneous and isotropic cosmological models. They also discussed the properties of these solutions. In this paper the authors relate the solutions of Pimentel and Diaz-Rivera by simple transformations to previous solutions published in the literature, showing that all the solutions can be derived from the known existing ones. Drawbacks to these approaches of studying bulk viscosity are pointed out, and better approaches indicated

  8. Application of Hyphenated Techniques in Speciation Analysis of Arsenic, Antimony, and Thallium

    Directory of Open Access Journals (Sweden)

    Rajmund Michalski

    2012-01-01

    Full Text Available Due to the fact that metals and metalloids have a strong impact on the environment, the methods of their determination and speciation have received special attention in recent years. Arsenic, antimony, and thallium are important examples of such toxic elements. Their speciation is especially important in the environmental and biomedical fields because of their toxicity, bioavailability, and reactivity. Recently, speciation analytics has been playing a unique role in the studies of biogeochemical cycles of chemical compounds, determination of toxicity and ecotoxicity of selected elements, quality control of food products, control of medicines and pharmaceutical products, technological process control, research on the impact of technological installation on the environment, examination of occupational exposure, and clinical analysis. Conventional methods are usually labor intensive, time consuming, and susceptible to interferences. The hyphenated techniques, in which separation method is coupled with multidimensional detectors, have become useful alternatives. The main advantages of those techniques consist in extremely low detection and quantification limits, insignificant interference, influence as well as high precision and repeatability of the determinations. In view of their importance, the present work overviews and discusses different hyphenated techniques used for arsenic, antimony, and thallium species analysis, in different clinical, environmental and food matrices.

  9. Application of Hyphenated Techniques in Speciation Analysis of Arsenic, Antimony, and Thallium

    Science.gov (United States)

    Michalski, Rajmund; Szopa, Sebastian; Jabłońska, Magdalena; Łyko, Aleksandra

    2012-01-01

    Due to the fact that metals and metalloids have a strong impact on the environment, the methods of their determination and speciation have received special attention in recent years. Arsenic, antimony, and thallium are important examples of such toxic elements. Their speciation is especially important in the environmental and biomedical fields because of their toxicity, bioavailability, and reactivity. Recently, speciation analytics has been playing a unique role in the studies of biogeochemical cycles of chemical compounds, determination of toxicity and ecotoxicity of selected elements, quality control of food products, control of medicines and pharmaceutical products, technological process control, research on the impact of technological installation on the environment, examination of occupational exposure, and clinical analysis. Conventional methods are usually labor intensive, time consuming, and susceptible to interferences. The hyphenated techniques, in which separation method is coupled with multidimensional detectors, have become useful alternatives. The main advantages of those techniques consist in extremely low detection and quantification limits, insignificant interference, influence as well as high precision and repeatability of the determinations. In view of their importance, the present work overviews and discusses different hyphenated techniques used for arsenic, antimony, and thallium species analysis, in different clinical, environmental and food matrices. PMID:22654649

  10. Speciation issues in food control - are we ready?

    International Nuclear Information System (INIS)

    Sloth, J.J.; Hedegaard, R.V.; Julshamn, K.; Trier, X.T.; Larsen, E.H.

    2009-01-01

    Full text: Our understanding of the mechanisms of biological activities and biotransformation of trace elements has improved during recent years with the help of chemical speciation studies. However, the most important practical application of elemental speciation is in the area of toxicology. Toxicological knowledge on the individual chemical elemental species should lead to more specific legislation of hazardous substances. Presently, European legislation concerning food safety is based on total element concentrations expressed as maximum limits. The lecture focuses on the present situation for speciation in food control and discusses the latest and expected future developments within this area. (author)

  11. Selenium speciation from farm to faeces

    International Nuclear Information System (INIS)

    Larsen, E.H.; Kapolna, E.; Hillestroem, P.R.; Laursen, K.; Budek, A.; Husted, S.; Buegel, S.

    2009-01-01

    Full text:The content and speciation of Se were studied in food crops originating from organic and conventional cultivation schemes. Additionally, carrots and onions were biofortified and intrinsically labelled using foliar spraying with isotopically enriched 77 SeO 3 -2 . HPLC-ICPMS and HPLC-ESIMS/MS analysis revealed that Se was mainly metabolized to 77 SeMet and to Me 77 SeCys, also in carrot. The 77 Se plants were processed to food (50 μg 77 Se/d) for a human intervention study. The isotopic enrichment by 77 Se as well as 67 Zn and 65 Cu in urine and faeces was determined by ICP(DRC)MS and the mineral absorption rates estimated. (author)

  12. Chemical speciation of radionuclides migrating in groundwaters

    International Nuclear Information System (INIS)

    Robertson, D.; Schilk, A.; Abel, K.; Lepel, E.; Thomas, C.; Pratt, S.; Cooper, E.; Hartwig, P.; Killey, R.

    1994-04-01

    In order to more accurately predict the rates and mechanisms of radionuclide migration from low-level waste disposal facilities via groundwater transport, ongoing studies are being conducted at field sites at Chalk River Laboratories to identify and characterize the chemical speciation of mobile, long-lived radionuclides migrating in groundwaters. Large-volume water sampling techniques are being utilized to separate and concentrate radionuclides into particular, cationic, anionic, and nonionic chemical forms. Most radionuclides are migrating as soluble, anionic species that appear to be predominantly organoradionuclide complexes. Laboratory studies utilizing anion exchange chromatography have separated several anionically complexed radionuclides, e.g., 60 Co and 106 Ru, into a number of specific compounds or groups of compounds. Further identification of the anionic organoradionuclide complexes is planned utilizing high resolution mass spectrometry. Large-volume ultra-filtration experiments are characterizing the particulate forms of radionuclides being transported in these groundwaters

  13. Sex chromosomes and speciation in Drosophila

    Science.gov (United States)

    Presgraves, Daven C.

    2010-01-01

    Two empirical rules suggest that sex chromosomes play a special role in speciation. The first is Haldane's rule— the preferential sterility and inviability of species hybrids of the heterogametic (XY) sex. The second is the disproportionately large effect of the X chromosome in genetic analyses of hybrid sterility. Whereas the causes of Haldane's rule are well established, the causes of the ‘large X-effect’ have remained controversial. New genetic analyses in Drosophila confirm that the X is a hotspot for hybrid male sterility factors, providing a proximate explanation for the large X-effect. Several other new findings— on faster X evolution, X chromosome meiotic drive, and the regulation of the X chromosome in the male-germline— provide plausible evolutionary explanations for the large X-effect. PMID:18514967

  14. Bulk monitoring and segregation of radioactive wastes

    Energy Technology Data Exchange (ETDEWEB)

    Beddow, H.; Adsley, I.; Pearman, I.; Sweeney, A.; Davies, M., E-mail: helen.beddow@nuvia.co.uk [Nuvia Limited, Harwell Oxford, Didcot, Oxfordshire (United Kingdom)

    2014-07-01

    Several sites in the UK are contaminated by radioactive legacy wastes. These include; radium luminising sites and more recently the oil, and (potentially) fracking industries; sites contaminated from thorium gas mantle factories; old nuclear research sites; nuclear power sites, and the Sellafield reprocessing site. Nuvia has developed a suite of technologies to map the location of and to recover and process wastes during remedial operations. The main method for delineating contaminated areas in-situ is by use of the Groundhog system, whilst bulk monitoring methods employ the Gamma Excavation Monitor, the High Resolution Assay Monitor, and the Conveyor Active Particle System. (author)

  15. Bulk monitoring and segregation of radioactive wastes

    International Nuclear Information System (INIS)

    Beddow, H.; Adsley, I.; Pearman, I.; Sweeney, A.; Davies, M.

    2014-01-01

    Several sites in the UK are contaminated by radioactive legacy wastes. These include; radium luminising sites and more recently the oil, and (potentially) fracking industries; sites contaminated from thorium gas mantle factories; old nuclear research sites; nuclear power sites, and the Sellafield reprocessing site. Nuvia has developed a suite of technologies to map the location of and to recover and process wastes during remedial operations. The main method for delineating contaminated areas in-situ is by use of the Groundhog system, whilst bulk monitoring methods employ the Gamma Excavation Monitor, the High Resolution Assay Monitor, and the Conveyor Active Particle System. (author)

  16. Selective arsenic speciation analysis of human urine reference materials using gradient elution ion-exchange HPLC-ICP-MS

    DEFF Research Database (Denmark)

    Sloth, Jens Jørgen; Larsen, Erik Huusfeldt; Julshamn, K.

    2004-01-01

    identical with the reference values given for total arsenic. The obtained values for arsenobetaine and dimethylarsinic acid were identical with the values certified for the NIES No. 18 urine CRM. The speciation data presented here may be valuable for the quality assurance of analytical method development...

  17. Selenium speciation analysis of Misgurnus anguillicaudatus selenoprotein by HPLC-ICP-MS and HPLC-ESI-MS/MS

    Science.gov (United States)

    Analytical methods for selenium (Se) speciation were developed using high performance liquid chromatography (HPLC) coupled to either inductively coupled plasma mass spectrometry (ICP-MS) or electrospray ionization tandem mass spectrometry (ESI-MS/MS). Separations of selenomethionine (Se-Met) and sel...

  18. Zirconium based bulk metallic glasses

    International Nuclear Information System (INIS)

    Dey, G.K.; Neogy, S.; Savalia, R.T.; Tewari, R.; Srivastava, D.; Banerjee, S.

    2006-01-01

    Metallic glasses have come into prominence in recent times because their nanocrystalline atomic arrangement imparts many useful and unusual properties to these metallic solids. In this study, bulk glasses have been obtained in Zr based multicomponent alloy by induction melting these alloys in silica crucibles and casting these in form of rods 3 and 6 mm in diameter in a copper mould

  19. Longitudinal bulk acoustic mass sensor

    DEFF Research Database (Denmark)

    Hales, Jan Harry; Teva, Jordi; Boisen, Anja

    2009-01-01

    A polycrystalline silicon longitudinal bulk acoustic cantilever is fabricated and operated in air at 51 MHz. A mass sensitivity of 100 Hz/fg (1 fg=10(-15) g) is obtained from the preliminary experiments where a minute mass is deposited on the device by means of focused ion beam. The total noise...

  20. Bulk viscosity of molecular fluids

    Science.gov (United States)

    Jaeger, Frederike; Matar, Omar K.; Müller, Erich A.

    2018-05-01

    The bulk viscosity of molecular models of gases and liquids is determined by molecular simulations as a combination of a dilute gas contribution, arising due to the relaxation of internal degrees of freedom, and a configurational contribution, due to the presence of intermolecular interactions. The dilute gas contribution is evaluated using experimental data for the relaxation times of vibrational and rotational degrees of freedom. The configurational part is calculated using Green-Kubo relations for the fluctuations of the pressure tensor obtained from equilibrium microcanonical molecular dynamics simulations. As a benchmark, the Lennard-Jones fluid is studied. Both atomistic and coarse-grained force fields for water, CO2, and n-decane are considered and tested for their accuracy, and where possible, compared to experimental data. The dilute gas contribution to the bulk viscosity is seen to be significant only in the cases when intramolecular relaxation times are in the μs range, and for low vibrational wave numbers (<1000 cm-1); This explains the abnormally high values of bulk viscosity reported for CO2. In all other cases studied, the dilute gas contribution is negligible and the configurational contribution dominates the overall behavior. In particular, the configurational term is responsible for the enhancement of the bulk viscosity near the critical point.

  1. INORGANIC ARSENIC SPECIATION IN THE ATMOSPHERE: STUDY IN ISFAHAN

    Directory of Open Access Journals (Sweden)

    A KALANTARI

    2000-06-01

    Full Text Available Introduction. Arsenic is one of the most hazardous elements that associate with airborne particulate matter in the atmosphere. Among the different species of arsenic, ASIII has the most toxic and carcinogenic property between any other kind of this element. Arsenic speciation is important in environmental studies. Methods. We collected 59 samples of airborne particulate matter from the atmosphere in Isfahan in a three months period by a high volume air sampler with a flow rate of 1 m3 min-1. Air particulates were collected on the paper filter (Whatman No.41. Four different digestive procedures were examined in order to find the best method. At last we chose digestion of filter with HCI (10-4N due to its feasibility, cost benefit and efficacy. Other methods that examined were digestion of filter with a mixture of HN03 and H2O2, with a mixture of HNO3 and H2O2 and with HCI (1 N. The determination of As3+ and As5+ concentrations were performed by hydrIde generation atomic absorption spectrometry. The effect of Ph on the absorption signal was also investigated in arsenic speciation. Results. Average of total saspended particles (TSP in July, August, and September 1998 were 223, 172, and 247 mg.m3 respectively. The recovery of arsenic from airborne particulate matter was almost the same for the different digestion methods. The concentration and volume of NaBH4 was optimized for determining of different species of arsenic. At pH=5, Asv didn't produce any absorption signal. So, the determination of ASm was carried out easilyat the above mentioned pH. The concentrations of total arsenic were determined in 47 samples. The mean concentrations of total arsenic in July, August and September were 3.31, 2.01 and 2.6, respectively. Discussion. More than 50 percent of total atmospheric arsenic exists as ASIII which is the most toxic and carcinogenic forms of this element. So, it is recommended to make a suitable policy for decreasing of this hazardous

  2. Speciated arsenic in air: measurement methodology and risk assessment considerations.

    Science.gov (United States)

    Lewis, Ari S; Reid, Kim R; Pollock, Margaret C; Campleman, Sharan L

    2012-01-01

    Accurate measurement of arsenic (As) in air is critical to providing a more robust understanding of arsenic exposures and associated human health risks. Although there is extensive information available on total arsenic in air, less is known on the relative contribution of each arsenic species. To address this data gap, the authors conducted an in-depth review of available information on speciated arsenic in air. The evaluation included the type of species measured and the relative abundance, as well as an analysis of the limitations of current analytical methods. Despite inherent differences in the procedures, most techniques effectively separated arsenic species in the air samples. Common analytical techniques such as inductively coupled plasma mass spectrometry (ICP-MS) and/or hydride generation (HG)- or quartz furnace (GF)-atomic absorption spectrometry (AAS) were used for arsenic measurement in the extracts, and provided some of the most sensitive detection limits. The current analysis demonstrated that, despite limited comparability among studies due to differences in seasonal factors, study duration, sample collection methods, and analytical methods, research conducted to date is adequate to show that arsenic in air is mainly in the inorganic form. Reported average concentrations of As(III) and As(V) ranged up to 7.4 and 10.4 ng/m3, respectively, with As(V) being more prevalent than As(III) in most studies. Concentrations of the organic methylated arsenic compounds are negligible (in the pg/m3 range). However because of the variability in study methods and measurement methodology, the authors were unable to determine the variation in arsenic composition as a function of source or particulate matter (PM) fraction. In this work, the authors include the implications of arsenic speciation in air on potential exposure and risks. The authors conclude that it is important to synchronize sample collection, preparation, and analytical techniques in order to generate

  3. Use of imidazole 4,5-dicarboxylic acid in vanadium speciation

    International Nuclear Information System (INIS)

    Banerjee, D.; Mondal, B.C.; Das, D.; Das, A.K.

    2003-01-01

    A new resin has been synthesized by fictionalization of polystyrene-divinylbenzene (8 %) with imidazole 4,5-dicarboxylic acid through -N=N- bonding. The resulting resin has been characterized by elemental analysis, thermogravimetric analysis, infrared spectroscopy, hydrogen ion capacity and metal ion capacity. The speciation study of vanadium has been studied by using this resin and the maximum exchange capacity was found to be 0.45 mmol g -1 for V 4+ and that for V 5+ was 1.57 mmol g -1 at pH 3 for both. The eluents malonic acid and sodium hydroxide have been used for the selective separation of vanadium(IV) and vanadium(V) species respectively. The effects of diverse ions on the sorption and recovery of each species have been studied. Finally, the developed method has been applied for the speciation and determination of these two species in natural water samples. (author)

  4. Genetic structure and bio-climatic modeling support allopatric over parapatric speciation along a latitudinal gradient

    Directory of Open Access Journals (Sweden)

    Rossetto Maurizio

    2012-08-01

    Full Text Available Abstract Background Four of the five species of Telopea (Proteaceae are distributed in a latitudinal replacement pattern on the south-eastern Australian mainland. In similar circumstances, a simple allopatric speciation model that identifies the origins of genetic isolation within temporal geographic separation is considered as the default model. However, secondary contact between differentiated lineages can result in similar distributional patterns to those arising from a process of parapatric speciation (where gene flow between lineages remains uninterrupted during differentiation. Our aim was to use the characteristic distributional patterns in Telopea to test whether it reflected the evolutionary models of allopatric or parapatric speciation. Using a combination of genetic evidence and environmental niche modelling, we focused on three main questions: do currently described geographic borders coincide with genetic and environmental boundaries; are there hybrid zones in areas of secondary contact between closely related species; did species distributions contract during the last glacial maximum resulting in distributional gaps even where overlap and hybridisation currently occur? Results Total genomic DNA was extracted from 619 individuals sampled from 36 populations representing the four species. Seven nuclear microsatellites (nSSR and six chloroplast microsatellites (cpSSR were amplified across all populations. Genetic structure and the signature of admixture in overlap zones was described using the Bayesian clustering methods implemented in STUCTURE and NewHybrids respectively. Relationships between chlorotypes were reconstructed as a median-joining network. Environmental niche models were produced for all species using environmental parameters from both the present day and the last glacial maximum (LGM. The nSSR loci amplified a total of 154 alleles, while data for the cpSSR loci produced a network of six chlorotypes. STRUCTURE revealed

  5. Genetic structure and bio-climatic modeling support allopatric over parapatric speciation along a latitudinal gradient.

    Science.gov (United States)

    Rossetto, Maurizio; Allen, Chris B; Thurlby, Katie A G; Weston, Peter H; Milner, Melita L

    2012-08-20

    Four of the five species of Telopea (Proteaceae) are distributed in a latitudinal replacement pattern on the south-eastern Australian mainland. In similar circumstances, a simple allopatric speciation model that identifies the origins of genetic isolation within temporal geographic separation is considered as the default model. However, secondary contact between differentiated lineages can result in similar distributional patterns to those arising from a process of parapatric speciation (where gene flow between lineages remains uninterrupted during differentiation). Our aim was to use the characteristic distributional patterns in Telopea to test whether it reflected the evolutionary models of allopatric or parapatric speciation. Using a combination of genetic evidence and environmental niche modelling, we focused on three main questions: do currently described geographic borders coincide with genetic and environmental boundaries; are there hybrid zones in areas of secondary contact between closely related species; did species distributions contract during the last glacial maximum resulting in distributional gaps even where overlap and hybridisation currently occur? Total genomic DNA was extracted from 619 individuals sampled from 36 populations representing the four species. Seven nuclear microsatellites (nSSR) and six chloroplast microsatellites (cpSSR) were amplified across all populations. Genetic structure and the signature of admixture in overlap zones was described using the Bayesian clustering methods implemented in STUCTURE and NewHybrids respectively. Relationships between chlorotypes were reconstructed as a median-joining network. Environmental niche models were produced for all species using environmental parameters from both the present day and the last glacial maximum (LGM).The nSSR loci amplified a total of 154 alleles, while data for the cpSSR loci produced a network of six chlorotypes. STRUCTURE revealed an optimum number of five clusters

  6. Time-dependent changes of zinc speciation in four soils contaminated with zincite or sphalerite.

    Science.gov (United States)

    Voegelin, Andreas; Jacquat, Olivier; Pfister, Sabina; Barmettler, Kurt; Scheinost, Andreas C; Kretzschmar, Ruben

    2011-01-01

    The long-term speciation of Zn in contaminated soils is strongly influenced by soil pH, clay, and organic matter content as well as Zn loading. In addition, the type of Zn-bearing contaminant entering the soil may influence the subsequent formation of pedogenic Zn species, but systematic studies on such effects are currently lacking. We therefore conducted a soil incubation study in which four soils, ranging from strongly acidic to calcareous, were spiked with 2000 mg/kg Zn using either ZnO (zincite) or ZnS (sphalerite) as the contamination source. The soils were incubated under aerated conditions in moist state for up to four years. The extractability and speciation of Zn were assessed after one, two, and four years using extractions with 0.01 M CaCl(2) and Zn K-edge X-ray absorption fine structure (XAFS) spectroscopy, respectively. After four years, more than 90% of the added ZnO were dissolved in all soils, with the fastest dissolution occurring in the acidic soils. Contamination with ZnO favored the formation of Zn-bearing layered double hydroxides (LDH), even in acidic soils, and to a lesser degree Zn-phyllosilicates and adsorbed Zn species. This was explained by locally elevated pH and high Zn concentrations around dissolving ZnO particles. Except for the calcareous soil, ZnS dissolved more slowly than ZnO, reaching only 26 to 75% of the added ZnS after four years. ZnS dissolved more slowly in the two acidic soils than in the near-neutral and the calcareous soil. Also, the resulting Zn speciation was markedly different between these two pairs of soils: Whereas Zn bound to hydroxy-interlayered clay minerals (HIM) and octahedrally coordinated Zn sorption complexes prevailed in the two acidic soils, Zn speciation in the neutral and the calcareous soil was dominated by Zn-LDH and tetrahedrally coordinated inner-sphere Zn complexes. Our results show that the type of Zn-bearing contaminant phase can have a significant influence on the formation of pedogenic Zn

  7. Gap-related trapped magnetic flux dependence between single and combined bulk superconductors

    Science.gov (United States)

    Deng, Z.; Miki, M.; Felder, B.; Tsuzuki, K.; Shinohara, N.; Uetake, T.; Izumi, M.

    2011-05-01

    Aiming at examining the trapped-flux dependence between single and combined bulk superconductors for field-pole applications, three rectangular Y 1.65Ba 2Cu 3O 7-x (YBCO) bulks with a possibly compact combination were employed to investigate the trapped-flux characteristics of single and combined bulks with a field-cooling magnetization (FCM) method. A gap-related dependence was found between them. At lower gaps of 1 mm and 5 mm, the peak trapped fields and total magnetic flux of combined bulks are both smaller than the additive values of each single bulk, which can be ascribed to the demagnetization influences of the field around the bulk generated by the adjacent ones. While, at larger gaps like 10 mm, the situation becomes reversed. The combined bulks can attain bigger peak trapped fields as well as total magnetic flux, which indicates that the magnetic field by the bulk combination can reach higher gaps, thanks to the bigger magnetic energy compared with the single bulk. The presented results show that, on one hand, it is possible to estimate the total trapped magnetic flux of combined bulks by an approximate additive method of each single bulk while considering a demagnetization factor; on the other hand, it also means that the performance of combined bulks will be superior to the addition of each single bulk at larger gaps, thus preferable for large-scaled magnet applications.

  8. Solid phase extraction for the speciation and preconcentration of inorganic selenium in water samples: a review.

    Science.gov (United States)

    Herrero Latorre, C; Barciela García, J; García Martín, S; Peña Crecente, R M

    2013-12-04

    Selenium is an essential element for the normal cellular function of living organisms. However, selenium is toxic at concentrations of only three to five times higher than the essential concentration. The inorganic forms (mainly selenite and selenate) present in environmental water generally exhibit higher toxicity (up to 40 times) than organic forms. Therefore, the determination of low levels of different inorganic selenium species in water is an analytical challenge. Solid-phase extraction has been used as a separation and/or preconcentration technique prior to the determination of selenium species due to the need for accurate measurements for Se species in water at extremely low levels. The present paper provides a critical review of the published methods for inorganic selenium speciation in water samples using solid phase extraction as a preconcentration procedure. On the basis of more than 75 references, the different speciation strategies used for this task have been highlighted and classified. The solid-phase extraction sorbents and the performance and analytical characteristics of the developed methods for Se speciation are also discussed. Copyright © 2013 Elsevier B.V. All rights reserved.

  9. Stability of Tl(III) in the context of speciation analysis of thallium in plants.

    Science.gov (United States)

    Sadowska, Monika; Biaduń, Ewa; Krasnodębska-Ostręga, Beata

    2016-02-01

    The paper presents both "good" and "bad" results obtained during speciation analysis of thallium in plant tissues of a hyperaccumulator of this metal. The object was white mustard - Sinapis alba L. In this plant there were found traces of trivalent thallium. The crucial point of this study (especially in the case of so unstable thallium form as Tl(III)) was to prove that the presence of Tl(III) was not caused by the procedure of sample preparation itself, and that the whole analytical method provides reliable results. Choice of the method for conservation of the initial speciation, extraction with the highest efficiency and proving the correctness of the obtained data were the most difficult parts of the presented study. It was found that: both freezing and drying cause significant changes in the speciation of thallium; quantitative analysis could be performed only with fresh tissues of mustard plants; only short-term storage of an extract from fresh plant tissues is possible; the methodology is not the source of thallium (III); only the presence of DTPA can greatly limit the reduction of TI(III) to TI(I) (up to 1-3%); the UV irradiation results in disintegration of TI(III)DTPA in the presence of plant matrix (reduction up to 90%). Copyright © 2015 Elsevier Ltd. All rights reserved.

  10. Carbon speciation in ash, residual waste and contaminated soil by thermal and chemical analyses.

    Science.gov (United States)

    Kumpiene, Jurate; Robinson, Ryan; Brännvall, Evelina; Nordmark, Désirée; Bjurström, Henrik; Andreas, Lale; Lagerkvist, Anders; Ecke, Holger

    2011-01-01

    Carbon in waste can occur as inorganic (IC), organic (OC) and elemental carbon (EC) each having distinct chemical properties and possible environmental effects. In this study, carbon speciation was performed using thermogravimetric analysis (TGA), chemical degradation tests and the standard total organic carbon (TOC) measurement procedures in three types of waste materials (bottom ash, residual waste and contaminated soil). Over 50% of the total carbon (TC) in all studied materials (72% in ash and residual waste, and 59% in soil) was biologically non-reactive or EC as determined by thermogravimetric analyses. The speciation of TOC by chemical degradation also showed a presence of a non-degradable C fraction in all materials (60% of TOC in ash, 30% in residual waste and 13% in soil), though in smaller amounts than those determined by TGA. In principle, chemical degradation method can give an indication of the presence of potentially inert C in various waste materials, while TGA is a more precise technique for C speciation, given that waste-specific method adjustments are made. The standard TOC measurement yields exaggerated estimates of organic carbon and may therefore overestimate the potential environmental impacts (e.g. landfill gas generation) of waste materials in a landfill environment. Copyright © 2010 Elsevier Ltd. All rights reserved.

  11. Speciation of the plutonium at trace levels by capillary electrophoresis-ICP-MS coupling

    International Nuclear Information System (INIS)

    Ambard, Ch.

    2007-01-01

    The CE-ICP-MS coupling allowed the development of new analytical methods for the study of plutonium (Pu) speciation at trace levels including complexation studies of this element by organic and inorganic ligands. First, a method, called dual detection, based on the simultaneous use of the UV-Visible spectrophotometer integrated in the capillary electrophoresis and the ICP-MS was developed and validated. It allows the unambiguous determination of electrophoretic mobilities for separated chemical species and gives a powerful tool for speciation studies. Then, the influence on Pu redox speciation of the buffer from the background electrolyte was evaluated. This study showed the implications of the electrolyte constituents' choice on Pu redox equilibrium in the sample. Furthermore, the CE-ICP-MS coupling was used for studying the Pu complexation at trace levels by some organic (NTA and DTPA) and inorganic ligands (carbonates). The behaviour of Pu valence +III, +IV and +VI was studied in the presence of buffer at near neutral pH. Different species of Pu were observed depending on the initial oxidation state of the plutonium. The study showed the potential of poly-amino-carboxylic acids, such as NTA and DTPA, for dissolving Pu precipitates, regardless its initial speciation. Finally, the carbonation of pentavalent neptunium, as an analogue of Pu(V), was achieved at very low concentration of Np (10 -8 mol.L -1 ). The formation of NpO 2 (CO 3 ) - at 25 C and 2,5*10 -2 mol.L -1 ionic strength was measured by CE-ICP-MS and found to consistent with literature data. (author)

  12. Speciation of the plutonium at trace levels by capillary electrophoresis-ICP-MS coupling

    International Nuclear Information System (INIS)

    Ambard, Ch.

    2007-01-01

    The CE-ICP-MS coupling allowed the development of new analytical methods for the study of plutonium speciation at trace levels including complexation studies of this element by organic and inorganic ligands. First, a method, called dual detection, based on the simultaneous use of the UV-Visible spectrophotometer integrated in the capillary electrophoresis and the ICPMS was developed and validated. It allows the unambiguous determination of electrophoretic mobilities for separated chemical species and gives a powerful tool for speciation studies. Then, the influence on plutonium redox speciation of the buffer from the background electrolyte was evaluated. This study showed the implications of the electrolyte constituents' choice on plutonium redox equilibrium in the sample. Furthermore, the CE-ICP-MS coupling was used for studying the plutonium complexation at trace levels by some organic (NTA and DTPA) and inorganic ligands (carbonates). The behaviour of plutonium valence +III, +IV and +VI was studied in the presence of buffer at near neutral pH. Different species of plutonium were observed depending on the initial oxidation state of the plutonium. This study showed the potential of poly-amino-carboxylic acids, such as NTA and DTPA, for dissolving plutonium precipitates, regardless its initial speciation. Finally, the carbonation of pentavalent neptunium, as an analogue of Pu(V), was achieved at very low concentration of Np (10 -8 mol.L -1 ). The formation constant of NpO 2 (CO 3 )- at 25 deg. C and 2,5 x 10 -2 mol.L -1 ionic strength was measured by CE-ICP-MS and found to be consistent with literature data. (author)

  13. saosakwe@yahoo.com Chemical Speciation and Mobility of Some

    African Journals Online (AJOL)

    Michael Horsfall

    ABSTRACT: The mobility of some heavy metals (Fe, Co, Ni and Mn) in soils around ... Sampling and Analysis: Soil samples were collected ..... Speciation Studies of trace elements levels in .... Characterization of Radioactive Particles in the.

  14. Pb Speciation Data to Estimate Lead Bioavailability to Quail

    Data.gov (United States)

    U.S. Environmental Protection Agency — Linear combination fitting data for lead speciation of soil samples evaluated through an in-vivo/in-vitro correlation for quail exposure. This dataset is associated...

  15. Speciation and Persistence of Dimethoate in the Aquatic Environment

    African Journals Online (AJOL)

    Speciation and Persistence of Dimethoate in the Aquatic Environment: Characterization in Terms of a Rate Model that Takes Into Account Hydrolysis, Photolysis, Microbial Degradation and Adsorption of the Pesticide by Colloidal and Sediment Particles.

  16. Genomic support for speciation and specificity of baculoviruses

    NARCIS (Netherlands)

    Jakubowska, A.K.

    2010-01-01

    Keywords: baculovirus, insects, speciation, genomics, phylogeny, host specificity

    The Baculoviridae comprise a large family of double-stranded DNA viruses infecting
    arthropods. In this thesis two baculoviruses, Leucoma salicis nucleopolyhedrovirus
    (LesaNPV) and Agrotis

  17. Surface barrier and bulk pinning in MgB$_2$ superconductor

    OpenAIRE

    Pissas, M.; Moraitakis, E.; Stamopoulos, D.; Papavassiliou, G.; Psycharis, V.; Koutandos, S.

    2001-01-01

    We present a modified method of preparation of the new superconductor MgB$_2$. The polycrystalline samples were characterized using x-ray and magnetic measurements. The surface barriers control the isothermal magnetization loops in powder samples. In bulk as prepared samples we always observed symmetric magnetization loops indicative of the presence of a bulk pinning mechanism. Magnetic relaxation measurements in the bulk sample reveal a crossover of surface barrier to bulk pinning.

  18. How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

    Science.gov (United States)

    Kam, K.; Lemke, K.

    2014-12-01

    The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with

  19. Development of the DGT technique for in-situ Pu speciation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Cusnir, R.; Bochud, F.; Froidevaux, P. [Institute of Radiation Physics, Lausanne University Hospital, Rue du Grand-Pre 1, CH-1007 Lausanne (Switzerland); Steinmann, P. [Federal Office of Public Health, Swarzenburgstrasse 165, CH-3003 Bern (Switzerland)

    2014-07-01

    Toxic effects of artificial radionuclides are strongly dependent on the surrounding chemical environment which determines the bioavailability of contaminant species. Speciation of plutonium in the environment is of particular interest since it is a long-life actinide contributing to the dose exposure via ingestion with water and food in case of radioactive discharge. Furthermore, natural colloids present in waters, as main carriers of dissolved trace metals, can transport plutonium over significant distances from contaminated sites. The diffusive gradients in thin films (DGT) technique is an efficient instrument for passive sampling of trace metals. It allows for in-situ monitoring of mean concentrations of bioavailable contaminant species (1). A DGT sampler consists of two gel layers: a polyacrylamide hydrogel diffusion layer allowing to diffuse labile metal species to the second, binding layer, impregnated with ion-exchange resin. Resin elution and further analysis allow determining the amount of the bioavailable fraction of trace metals in the bulk solution, which can be calculated from the relationship: C{sub bulk}= (M x Δg)/(D x t x A) where M is the measured metal species inventory in the resin, Δg the thickness of the diffusion layer, D the diffusion coefficient of the species in the gel, t the time of deployment, A the diffusion area. To our knowledge, the DGT has not yet been applied for Pu speciation measurements and the D value is unknown. Here we propose the use of DGT to monitor the dissolved phase and labile complexes of plutonium in the aquatic environment. We have first measured the diffusion coefficient of plutonium in the hydrogel. Experiments were carried out in a diffusion cell (2) and with commercially available DGT samplers exposed in standardized solutions containing {sup 239}Pu at pico-molar concentrations. Both approaches give comparable D values in the range of 2.30 x 10{sup -6} - 2.45 x 10{sup -6} cm{sup 2} s{sup -1}. We then studied

  20. High resolution microprofiling, fractionation and speciation at sediment water interfaces

    Science.gov (United States)

    Fabricius, Anne-Lena; Duester, Lars; Ecker, Dennis; Ternes, Thomas A.

    2016-04-01

    Within aquatic environments, the exchange between the sediment and the overlaying water is often driven by steep gradients of, e.g., the oxygen concentration, the redox potential or the pH value at the sediment water interface (SWI). Important transport processes at the SWI are sedimentation and resuspension of particulate matter and diffusional fluxes of dissolved substances. To gain a better understanding of the key factors and processes determining the fate of substances at the SWI, methods with a spatial high resolution are required that enable the investigation of several sediment parameters in parallel to different analytes of interest in the sediment pore water. Moreover, beside the total content, questions concerning the speciation and fractionation are of concern in studying the different (transport) processes. Due to the availability of numerous micro-sensors and -electrodes (e.g., O2, redox potential, pH value, H2S, N2O) and the development of methods for pore water sampling [1], the toolbox to study the heterogeneous and often dynamic conditions at the SWI at a sub-millimetre scale were considerably improved. Nevertheless, the methods available for pore water sampling often require the installation of the sampling devices at the sampling site and/or intensive preparation procedures that may influence the conditions at the area studied and/or the characteristics of the samples taken. By combination of a micro profiling system with a new micro filtration probe head connected to a pump and a fraction collector, a micro profiling and micro sampling system ("missy") was developed that enables for the first time a direct, automate and low invasive sampling of small volumes (content of metal(loid)s, but also their fractionation (size dependent and micelle mediated) or speciation related distributions along sediment depth profiles in parallel to different sediment parameters (O2, redox and pH). Together with the results of missy-experiments, the results of

  1. Equilibrium Measurements of the NH3-CO2-H2O System: Speciation Based on Raman Spectroscopy and Multivariate Modeling

    Directory of Open Access Journals (Sweden)

    Maths Halstensen

    2017-01-01

    Full Text Available Liquid speciation is important for reliable process design and optimization of gas-liquid absorption process. Liquid-phase speciation methods are currently available, although they involve tedious and time-consuming laboratory work. Raman spectroscopy is well suited for in situ monitoring of aqueous chemical reactions. Here, we report on the development of a method for speciation of the CO2-NH3-H2O equilibrium using Raman spectroscopy and PLS-R modeling. The quantification methodology presented here offers a novel approach to provide rapid and reliable predictions of the carbon distribution of the CO2-NH3-H2O system, which may be used for process control and optimization. Validation of the reported speciation method which is based on independent, known, NH3-CO2-H2O solutions shows estimated prediction uncertainties for carbonate, bicarbonate, and carbamate of 6.45 mmol/kg H2O, 34.39 mmol/kg H2O, and 100.9 mmol/kg H2O, respectively.

  2. The reality and importance of founder speciation in evolution.

    Science.gov (United States)

    Templeton, Alan R

    2008-05-01

    A founder event occurs when a new population is established from a small number of individuals drawn from a large ancestral population. Mayr proposed that genetic drift in an isolated founder population could alter the selective forces in an epistatic system, an observation supported by recent studies. Carson argued that a period of relaxed selection could occur when a founder population is in an open ecological niche, allowing rapid population growth after the founder event. Selectable genetic variation can actually increase during this founder-flush phase due to recombination, enhanced survival of advantageous mutations, and the conversion of non-additive genetic variance into additive variance in an epistatic system, another empirically confirmed prediction. Templeton combined the theories of Mayr and Carson with population genetic models to predict the conditions under which founder events can contribute to speciation, and these predictions are strongly confirmed by the empirical literature. Much of the criticism of founder speciation is based upon equating founder speciation to an adaptive peak shift opposed by selection. However, Mayr, Carson and Templeton all modeled a positive interaction of selection and drift, and Templeton showed that founder speciation is incompatible with peak-shift conditions. Although rare, founder speciation can have a disproportionate importance in adaptive innovation and radiation, and examples are given to show that "rare" does not mean "unimportant" in evolution. Founder speciation also interacts with other speciation mechanisms such that a speciation event is not a one-dimensional process due to either selection alone or drift alone. (c) 2008 Wiley Periodicals, Inc.

  3. Electrochemical metal speciation in natural and model polyelectrolyte systems

    OpenAIRE

    Hoop, van den, M.A.G.T.

    1994-01-01

    The purpose of the research described in this thesis was to examine the applicability of electro-analytical techniques in obtaining information on the speciation of metals, i.e. their distribution over different physico-chemical forms, in aquatic systems containing charged macromolecules. In chapter 1 a general introduction is given to (i) metal speciation in aquatic systems, (ii) (bio)polyelectrolytes and their counterion distributions and (iii) electrochemical ...

  4. How humans drive speciation as well as extinction

    DEFF Research Database (Denmark)

    Bull, Joseph William; Maron, M.

    2016-01-01

    influence upon divergence in microorganisms. Even if human activities resulted in no net loss of species diversity by balancing speciation and extinction rates, this would probably be deemed unacceptable. We discuss why, based upon ‘no net loss’ conservation literature— considering phylogenetic diversity...... and other metrics, risk aversion, taboo trade-offs and spatial heterogeneity. We conclude that evaluating speciation alongside extinction could result in more nuanced understanding of biosphere trends, clarifying what it is we actually value about biodiversity....

  5. Investigation of chemical bond characteristics, thermal expansion coefficients and bulk moduli of alpha-R2MoO6 and R2Mo2O7 (R = rare earths) by using a dielectric chemical bond method.

    Science.gov (United States)

    Li, Huaiyong; Zhang, Siyuan; Zhou, Shihong; Cao, Xueqiang

    2009-09-01

    Theoretical researches are performed on the alpha-R2MoO6 (R = Y, Gd, Tb Dy, Ho, Er, Tm and Yb) and pyrochlore-type R2Mo2O7 (R = Y, Nd, Sm, Gd, Tb and Dy) rare earth molybdates by using chemical bond theory of dielectric description. The chemical bonding characteristics and their relationship with thermal expansion property and compressibility are explored. The calculated values of linear thermal expansion coefficient (LTEC) and bulk modulus agree well with the available experimental values. The calculations reveal that the LTECs and the bulk moduli do have linear relationship with the ionic radii of the lanthanides: the LTEC decreases from 6.80 to 6.62 10(-6)/K and the bulk modulus increases from 141 to 154 GPa when R goes in the order Gd, Tb Dy, Ho, Er, Tm, and Yb in the alpha-R2MoO6 series; while in the R2Mo2O7 series, the LTEC ranges from 6.80 to 6.61 10(-6)/K and the bulk modulus ranges from 147 to 163 GPa when R varies in the order Nd, Sm, Gd, Tb and Dy. Copyright 2008 Wiley Periodicals, Inc.

  6. LJUNGSKILE 1.0 A Computer Program for Investigation of Uncertainties in Chemical Speciation

    International Nuclear Information System (INIS)

    Ekberg, Christian; Oedegaard-Jensen, Arvid

    2002-11-01

    combine the both variables in a way that adequate pH/CO 2 partial pressure pairs are matched in the input vectors while LHS does not account for such correlations. Taken the generally rather poor degree of consistency, comparability and completeness in the existent thermodynamic data, however, such argumentation -justified as it is from a fundamental point of view- seems to be premature. It should be mentioned, however, that viable ways to account for correlation in input parameters have been reported in literature. The LJUNGSKILE program is written in C++ using the Borland C++ builder. The program is divided into two major parts. One part containing the chemical calculations and one containing the statistical methods used. The basic idea is to make many runs with PHREEQC and in each run the stability constants of interest are changed slightly within their respective confidence interval according to the statistical method used. Then, after each such cycle, if this option was selected, one of the factors may be changed by given increments to a given level, e.g. changing pH, and thus create a speciation diagram versus pH with uncertainty bands for each species concentration

  7. Cobalamin Concentrations in Fetal Liver Show Gender Differences: A Result from Using a High-Pressure Liquid Chromatography-Inductively Coupled Plasma Mass Spectrometry as an Ultratrace Cobalt Speciation Method.

    Science.gov (United States)

    Bosle, Janine; Goetz, Sven; Raab, Andrea; Krupp, Eva M; Scheckel, Kirk G; Lombi, Enzo; Meharg, Andrew A; Fowler, Paul A; Feldmann, Jörg

    2016-12-20

    Maternal diet and lifestyle choices may affect placental transfer of cobalamin (Cbl) to the fetus. Fetal liver concentration of Cbl reflects nutritional status with regards to vitamin B12, but at these low concentration current Cbl measurement methods lack robustness. An analytical method based on enzymatic extraction with subsequent reversed-phase-high-pressure liquid chromatography (RP-HPLC) separation and parallel ICPMS and electrospray ionization (ESI)-Orbitrap-MS to determine specifically Cbl species in liver samples of only 10-50 mg was developed using 14 pig livers. Subsequently 55 human fetal livers were analyzed. HPLC-ICPMS analysis for cobalt (Co) and Cbl gave detection limits of 0.18 ng/g and 0.88 ng/g d.m. in liver samples, respectively, with a recovery of >95%. Total Co (Co t ) concentration did not reflect the amount of Cbl or vitamin B12 in the liver. Cbl bound Co contributes only 45 ± 15% to Co t . XRF mapping and μXANES analysis confirmed the occurrence of non-Cbl cobalt in pig liver hot spots indicating particular Co. No correlations of total cobalt nor Cbl with fetal weight or weeks of gestation were found for the human fetal livers. Although no gender difference could be identified for total Co concentration, female livers were significantly higher in Cbl concentration (24.1 ± 7.8 ng/g) than those from male fetuses (19.8 ± 7.1 ng/g) (p = 0.04). This HPLC-ICPMS method was able to quantify total Co t and Cbl in fetus liver, and it was sensitive and precise enough to identify this gender difference.

  8. Calculated Bulk Properties of the Actinide Metals

    DEFF Research Database (Denmark)

    Skriver, Hans Lomholt; Andersen, O. K.; Johansson, B.

    1978-01-01

    Self-consistent relativistic calculations of the electronic properties for seven actinides (Ac-Am) have been performed using the linear muffin-tin orbitals method within the atomic-sphere approximation. Exchange and correlation were included in the local spin-density scheme. The theory explains...... the variation of the atomic volume and the bulk modulus through the 5f series in terms of an increasing 5f binding up to plutonium followed by a sudden localisation (through complete spin polarisation) in americium...

  9. Effects of water management on arsenic and cadmium speciation and accumulation in an upland rice cultivar.

    Science.gov (United States)

    Hu, Pengjie; Ouyang, Younan; Wu, Longhua; Shen, Libo; Luo, Yongming; Christie, Peter

    2015-01-01

    Pot and field experiments were conducted to investigate the effects of water regimes on the speciation and accumulation of arsenic (As) and cadmium (Cd) in Brazilian upland rice growing in soils polluted with both As and Cd. In the pot experiment constant and intermittent flooding treatments gave 3-16 times higher As concentrations in soil solution than did aerobic conditions but Cd showed the opposite trend. Compared to arsenate, there were more marked changes in the arsenite concentrations in the soil solution as water management shifted, and therefore arsenite concentrations dominated the As speciation and bioavailability in the soil. In the field experiment As concentrations in the rice grains increased from 0.14 to 0.21 mg/kg while Cd concentrations decreased from 0.21 to 0.02 mg/kg with increasing irrigation ranging from aerobic to constantly flooding conditions. Among the various water regimes the conventional irrigation treatment produced the highest rice grain yield of 6.29 tons/ha. The As speciation analysis reveals that the accumulation of dimethylarsinic acid (from 11.3% to 61.7%) made a greater contribution to the increase in total As in brown rice in the intermittent and constant flooding treatments compared to the intermittent-aerobic treatment. Thus, water management exerted opposite effects on Cd and As speciation and bioavailability in the soil and consequently on their accumulation in the upland rice. Special care is required when irrigation regime methods are employed to mitigate the accumulation of metal(loid)s in the grain of rice grown in soils polluted with both As and Cd. Copyright © 2014. Published by Elsevier B.V.

  10. Moving Speciation Genetics Forward: Modern Techniques Build on Foundational Studies in Drosophila.

    Science.gov (United States)

    Castillo, Dean M; Barbash, Daniel A

    2017-11-01

    The question of how new species evolve has been examined at every level, from macroevolutionary patterns of diversification to molecular population genetic analyses of specific genomic regions between species pairs. Drosophila has been at the center of many of these research efforts. Though our understanding of the speciation process has grown considerably over the past few decades, very few genes have been identified that contribute to barriers to reproduction. The development of advanced molecular genetic and genomic methods provides promising avenues for the rapid discovery of more genes that contribute to speciation, particularly those involving prezygotic isolation. The continued expansion of tools and resources, especially for species other than Drosophila melanogaster , will be most effective when coupled with comparative approaches that reveal the genetic basis of reproductive isolation across a range of divergence times. Future research programs in Drosophila have high potential to answer long-standing questions in speciation. These include identifying the selective forces that contribute to divergence between populations and the genetic basis of traits that cause reproductive isolation. The latter can be expanded upon to understand how the genetic basis of reproductive isolation changes over time and whether certain pathways and genes are more commonly involved. Copyright © 2017 by the Genetics Society of America.

  11. [Treatment of tannery wastewater by infiltration percolation: chromium removal and speciation in soil].

    Science.gov (United States)

    Tiglyene, S; Jaouad, A; Mandi, L

    2008-06-01

    The aim of this paper was, on one hand, to study the treatment of raw tannery effluent by infiltration percolation system and, on the other hand, to determine the distribution and speciation of chromium in the used soil. The system pilot consisted of columns filled to 15 cm of gravel and 60 cm of soil (88% of sand). The columns irrigated by raw tannery wastewater with a daily hydraulic load of 5 cm per day (approximately 10 L every day). The water flowed vertically through the soil. The speciation of Cr was investigated by using selective five steps sequential extraction method. The results indicated that the pH of the treated wastewater increases by three units in comparison to the raw wastewater. The electrical conductivity of the effluent increases also after treatment. Over the whole experimental period, results revealed significant performances of infiltration percolation system for organic load reduction. The mean elimination rate was 74% for total COD. In addition, there was a significant accumulation of organic carbon (62%) in the surface strata for the system. The total chromium undergoes an overall removal of 98%. After seven months of experiment, the results indicated that the whole retention of Cr occurring in the surface horizon of the soil (69%). Furthermore, the speciation study of Cr in the soil revealed that the oxidizable fraction is the most represented 55%. The reducible and residual phases represent 17.5% and 18.5%, respectively. The carbonate fraction presented 9% while exchangeable fraction presented only 0.02%.

  12. Steam Gasification of Sawdust Biochar Influenced by Chemical Speciation of Alkali and Alkaline Earth Metallic Species

    Directory of Open Access Journals (Sweden)

    Dongdong Feng

    2018-01-01

    Full Text Available The effect of chemical speciation (H2O/NH4Ac/HCl-soluble and insoluble of alkali and alkaline earth metallic species on the steam gasification of sawdust biochar was investigated in a lab-scale, fixed-bed reactor, with the method of chemical fractionation analysis. The changes in biochar structures and the evolution of biochar reactivity are discussed, with a focus on the contributions of the chemical speciation of alkali and alkaline earth metallic species (AAEMs on the steam gasification of biochar. The results indicate that H2O/NH4Ac/HCl-soluble AAEMs have a significant effect on biochar gasification rates. The release of K occurs mainly in the form of inorganic salts and hydrated ions, while that of Ca occurs mainly as organic ones. The sp3-rich or sp2-sp3 structures and different chemical-speciation AAEMs function together as the preferred active sites during steam gasification. H2O/HCl-soluble AAEMs could promote the transformation of biochar surface functional groups, from ether/alkene C-O-C to carboxylate COO− in biochar, while they may both be improved by NH4Ac-soluble AAEMs. H2O-soluble AAEMs play a crucial catalytic role in biochar reactivity. The effect of NH4Ac-soluble AAEMs is mainly concentrated in the high-conversion stage (biochar conversion >30%, while that of HCl-soluble AAEMs is reflected in the whole activity-testing stage.

  13. The variability in iron speciation in size fractionated residual oil fly ash particulate matter (ROFA PM).

    Science.gov (United States)

    Pattanaik, Sidhartha; Huggins, Frank E; Huffman, Gerald P

    2016-08-15

    Ambient particulate matter (PM) containing iron can catalyze Fenton reaction leading to the production of reactive oxygen species in cells. It can also catalyze atmospheric redox reaction. These reactions are governed by the physicochemical characteristics of iron in ambient PM. As a surrogate for ambient PM, we prepared residual oil fly ash PM (ROFA PM) in a practical fire tube boiler firing residual oils with varying sulfur and ash contents. The ROFA particles were resolved into fine PM or PM2.5 (aerodynamic diameter (AD)iron speciation in PM2.5+ was ascertained using X-ray absorption spectroscopy and leaching method while that in PM2.5 was reported earlier. The results of both studies are compared to get an insight into the variability in the iron speciation in different size fractions. The results show the predominance of ferric sulfate, with a minor spinal ferrite in both PM (i.e. ZnxNi1-xFe2O4 in PM2.5, ZnFe2O4 in PM2.5+). The iron solubility in ROFA PM depends on its speciation, mode of incorporation of iron into particle's carbonaceous matrix, the grade and composition of oils, and pH of the medium. The soluble fraction of iron in PM is critical in assessing its interaction with the biological systems and its toxic potential. Copyright © 2016 Elsevier B.V. All rights reserved.

  14. Sorption Speciation of Lanthanides/Actinides on Minerals by TRLFS, EXAFS and DFT Studies: A Review

    Directory of Open Access Journals (Sweden)

    Xiaoli Tan

    2010-11-01

    Full Text Available Lanthanides/actinides sorption speciation on minerals and oxides by means of time resolved laser fluorescence spectroscopy (TRLFS, extended X-ray absorption fine structure spectroscopy (EXAFS and density functional theory (DFT is reviewed in the field of nuclear disposal safety research. The theoretical aspects of the methods are concisely presented. Examples of recent research results of lanthanide/actinide speciation and local atomic structures using TRLFS, EXAFS and DFT are discussed. The interaction of lanthanides/actinides with oxides and minerals as well as their uptake are also of common interest in radionuclide chemistry. Especially the sorption and inclusion of radionuclides into several minerals lead to an improvement in knowledge of minor components in solids. In the solid-liquid interface, the speciation and local atomic structures of Eu(III, Cm(III, U(VI, and Np(IV/VI in several natural and synthetic minerals and oxides are also reviewed and discussed. The review is important to understand the physicochemical behavior of lanthanides/actinides at a molecular level in the natural environment.

  15. Elemental speciation of neptunium in ultra trace amount ranges

    International Nuclear Information System (INIS)

    Stoebener, Nils

    2013-01-01

    In the presented work, the detection of the isotope Np-237 with resonance ionization mass spectrometry (RIMS) was developed and optimized. In RIMS, sample atoms are excited and ionized with laser radiation in several, resonant steps and are subsequently detected by a mass spectrometer. Energy levels suitable for the excitation and ionization of Np-237 were identified using resonance ionization spectroscopy (RIS). With RIS, more than 300 previously unknown electronic states and autoionizing resonances of Np-237 were identified. Using in-source-RIMS, a limit of detection of 9E+5 atoms was demonstrated for the isotope. The mobility of Np in the environment strongly depends on its elemental speciation. Therefore, safety assessments of proposed nuclear waste repositories require analytical methods for the detection of Np species. CE (capillary electrophoresis) was hyphenated to ICP-MS (inductively coupled plasma mass spectrometry) to examine the distribution of the Np redox species Np(IV) and Np(V), which was possible at Np concentrations as low as 1E-9 mol/L. The method was used to study the interaction of the element with Opalinus Clay at varying conditions. CE-ICP-MS revealed, that under the presence of Fe(II), Np(V) is reduced to Np(IV), which is sorbed onto the clay. This leads to a higher overall Np sorption.

  16. Bulk Superconductors in Mobile Application

    Science.gov (United States)

    Werfel, F. N.; Delor, U. Floegel-; Rothfeld, R.; Riedel, T.; Wippich, D.; Goebel, B.; Schirrmeister, P.

    We investigate and review concepts of multi - seeded REBCO bulk superconductors in mobile application. ATZ's compact HTS bulk magnets can trap routinely 1 T@77 K. Except of magnetization, flux creep and hysteresis, industrial - like properties as compactness, power density, and robustness are of major device interest if mobility and light-weight construction is in focus. For mobile application in levitated trains or demonstrator magnets we examine the performance of on-board cryogenics either by LN2 or cryo-cooler application. The mechanical, electric and thermodynamical requirements of compact vacuum cryostats for Maglev train operation were studied systematically. More than 30 units are manufactured and tested. The attractive load to weight ratio is more than 10 and favours group module device constructions up to 5 t load on permanent magnet (PM) track. A transportable and compact YBCO bulk magnet cooled with in-situ 4 Watt Stirling cryo-cooler for 50 - 80 K operation is investigated. Low cooling power and effective HTS cold mass drives the system construction to a minimum - thermal loss and light-weight design.

  17. Development of speciation analysis for selenium in nutritional supplements by the determination of the seleno-methionine; Developpement de l'analyse de speciation du selenium dans des complements alimentaires par la determination de la selenomethionine

    Energy Technology Data Exchange (ETDEWEB)

    Sannac, S.; Labarraque, G.; Fisicaro, P. [Laboratoire National de Metrologie et d' Essai (LNE), 75 - Paris (France); Sannac, S.; Pannier, F.; Potin-Gautier, M. [Pau Univ. et des Pays de l' Adour, CNRS/UMR 5254, Lab. de Chimie Analytique, Bio-Inorganique et Environnement (IPREM), 64 (France)

    2009-07-01

    The development of a reference method in analytical chemistry is presented. Liquid chromatography with inductively coupled plasma mass spectrometry is employed to perform in speciation analysis. Applications are developed for the determination of seleno-methionine in nutritional supplements. The use of isotope dilution, a primary method, is required to enable measurement traceability. Method validation is ensured by the study of a certified reference material. (authors)

  18. Speciation of Bio-Available Iodine in Abalone (Haliotis discus hannai) by High-Performance Liquid Chromatography Hyphenated with Inductively Coupled Plasma-Mass Spectrometry Using an In Vitro Method.

    Science.gov (United States)

    Doh, Han Sol; Park, Hyun Jin

    2018-06-01

    Abalone is one of the most valuable marine products found in East Asia because it is rich in nutritious substances including iodine. In this study, the in vitro dialyzability approach was used to assess the bio-available iodine species in abalone. Iodide, iodate, 3-iodo-L-tyrosine (MIT), and 3,5-diiodo-L-tyrosine (DIT) were separated by high-performance liquid chromatography hyphenated with inductively coupled plasma-mass spectrometry (HPLC-ICP-MS). To assure the consistency, reliability, and accuracy of the data, the method was validated. Comparison of the total iodine in abalone muscle and viscera indicated that abalone muscle showed greater digestion/absorption efficiency than abalone viscera (digestion efficiency: 68.13 ± 2.59% and 47.88 ± 5.76% and absorption efficiency: 59.78 ± 2.93% and 35.12 ± 1.43% for abalone viscera and muscle, respectively). However, evaluation of the sum of the analyzed iodine species targeted in this study by HPLC-ICP-MS indicated that abalone muscle showed lower digestion efficiency and similar absorption efficiency compared to that of abalone viscera (digestion efficiency: 35.52 ± 5.41% and 28.84 ± 1.83%; absorption efficiency: 23.56 ± 4.38% and 27.56 ± 1.51% for abalone viscera and muscle, respectively). The main forms of iodine detected in abalone muscle were iodide and MIT, whereas iodide was the major form in abalone viscera. The bio-available iodine in abalone was quantified via an in vitro method employing HPLC-ICP-MS. The results of this study indicated that abalone is feasible as a new iodine source and may prospectively find application in iodine-fortified foods. © 2018 Institute of Food Technologists®.

  19. Sediment phosphorus speciation and mobility under dynamic redox conditions

    Science.gov (United States)

    Parsons, Chris T.; Rezanezhad, Fereidoun; O'Connell, David W.; Van Cappellen, Philippe

    2017-07-01

    Anthropogenic nutrient enrichment has caused phosphorus (P) accumulation in many freshwater sediments, raising concerns that internal loading from legacy P may delay the recovery of aquatic ecosystems suffering from eutrophication. Benthic recycling of P strongly depends on the redox regime within surficial sediment. In many shallow environments, redox conditions tend to be highly dynamic as a result of, among others, bioturbation by macrofauna, root activity, sediment resuspension and seasonal variations in bottom-water oxygen (O2) concentrations. To gain insight into the mobility and biogeochemistry of P under fluctuating redox conditions, a suspension of sediment from a hypereutrophic freshwater marsh was exposed to alternating 7-day periods of purging with air and nitrogen gas (N2), for a total duration of 74 days, in a bioreactor system. We present comprehensive data time series of bulk aqueous- and solid-phase chemistry, solid-phase phosphorus speciation and hydrolytic enzyme activities demonstrating the mass balanced redistribution of P in sediment during redox cycling. Aqueous phosphate concentrations remained low ( ˜ 2.5 µM) under oxic conditions due to sorption to iron(III) oxyhydroxides. During anoxic periods, once nitrate was depleted, the reductive dissolution of iron(III) oxyhydroxides released P. However, only 4.5 % of the released P accumulated in solution while the rest was redistributed between the MgCl2 and NaHCO3 extractable fractions of the solid phase. Thus, under the short redox fluctuations imposed in the experiments, P remobilization to the aqueous phase remained relatively limited. Orthophosphate predominated at all times during the experiment in both the solid and aqueous phase. Combined P monoesters and diesters accounted for between 9 and 16 % of sediment particulate P. Phosphatase activities up to 2.4 mmol h-1 kg-1 indicated the potential for rapid mineralization of organic P (Po), in particular during periods of aeration when the

  20. Uranium Speciation and Bioavailability in Aquatic Systems: An Overview

    Directory of Open Access Journals (Sweden)

    Scott J. Markich

    2002-01-01

    Full Text Available The speciation of uranium (U in relation to its bioavailability is reviewed for surface waters (fresh- and seawater and their sediments. A summary of available analytical and modeling techniques for determining U speciation is also presented. U(VI is the major form of U in oxic surface waters, while U(IV is the major form in anoxic waters. The bioavailability of U (i.e., its ability to bind to or traverse the cell surface of an organism is dependent on its speciation, or physicochemical form. U occurs in surface waters in a variety of physicochemical forms, including the free metal ion (U4+ or UO22+ and complexes with inorganic ligands (e.g., uranyl carbonate or uranyl phosphate, and humic substances (HS (e.g., uranyl fulvate in dissolved, colloidal, and/or particulate forms. Although the relationship between U speciation and bioavailability is complex, there is reasonable evidence to indicate that UO22+ and UO2OH+ are the major forms of U(VI available to organisms, rather than U in strong complexes (e.g., uranyl fulvate or adsorbed to colloidal and/or particulate matter. U(VI complexes with inorganic ligands (e.g., carbonate or phosphate and HS apparently reduce the bioavailability of U by reducing the activity of UO22+ and UO2OH+. The majority of studies have used the results from thermodynamic speciation modeling to support these conclusions. Time-resolved laser-induced fluorescence spectroscopy is the only analytical technique able to directly determine specific U species, but is limited in use to freshwaters of low pH and ionic strength. Nearly all of the available information relating the speciation of U to its bioavailability has been derived using simple, chemically defined experimental freshwaters, rather than natural waters. No data are available for estuarine or seawater. Furthermore, there are no available data on the relationship between U speciation and bioavailability in sediments. An understanding of this relationship has been

  1. Gap-related trapped magnetic flux dependence between single and combined bulk superconductors

    International Nuclear Information System (INIS)

    Deng, Z.; Miki, M.; Felder, B.; Tsuzuki, K.; Shinohara, N.; Uetake, T.; Izumi, M.

    2011-01-01

    Highlights: → Rectangular YBCO bulks to realize a compact combination. → The gap effect was added to consider in the trapped flux density mapping. → The trapped-flux dependence between single and combined bulks is gap related. → It is possible to estimate the total magnetic flux of bulk combinations. - Abstract: Aiming at examining the trapped-flux dependence between single and combined bulk superconductors for field-pole applications, three rectangular Y 1.65 Ba 2 Cu 3 O 7-x (YBCO) bulks with a possibly compact combination were employed to investigate the trapped-flux characteristics of single and combined bulks with a field-cooling magnetization (FCM) method. A gap-related dependence was found between them. At lower gaps of 1 mm and 5 mm, the peak trapped fields and total magnetic flux of combined bulks are both smaller than the additive values of each single bulk, which can be ascribed to the demagnetization influences of the field around the bulk generated by the adjacent ones. While, at larger gaps like 10 mm, the situation becomes reversed. The combined bulks can attain bigger peak trapped fields as well as total magnetic flux, which indicates that the magnetic field by the bulk combination can reach higher gaps, thanks to the bigger magnetic energy compared with the single bulk. The presented results show that, on one hand, it is possible to estimate the total trapped magnetic flux of combined bulks by an approximate additive method of each single bulk while considering a demagnetization factor; on the other hand, it also means that the performance of combined bulks will be superior to the addition of each single bulk at larger gaps, thus preferable for large-scaled magnet applications.

  2. Gap-related trapped magnetic flux dependence between single and combined bulk superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z., E-mail: zgdeng@gmail.co [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan); Miki, M.; Felder, B.; Tsuzuki, K.; Shinohara, N.; Uetake, T.; Izumi, M. [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan)

    2011-05-15

    Highlights: {yields} Rectangular YBCO bulks to realize a compact combination. {yields} The gap effect was added to consider in the trapped flux density mapping. {yields} The trapped-flux dependence between single and combined bulks is gap related. {yields} It is possible to estimate the total magnetic flux of bulk combinations. - Abstract: Aiming at examining the trapped-flux dependence between single and combined bulk superconductors for field-pole applications, three rectangular Y{sub 1.65}Ba{sub 2}Cu{sub 3}O{sub 7-x} (YBCO) bulks with a possibly compact combination were employed to investigate the trapped-flux characteristics of single and combined bulks with a field-cooling magnetization (FCM) method. A gap-related dependence was found between them. At lower gaps of 1 mm and 5 mm, the peak trapped fields and total magnetic flux of combined bulks are both smaller than the additive values of each single bulk, which can be ascribed to the demagnetization influences of the field around the bulk generated by the adjacent ones. While, at larger gaps like 10 mm, the situation becomes reversed. The combined bulks can attain bigger peak trapped fields as well as total magnetic flux, which indicates that the magnetic field by the bulk combination can reach higher gaps, thanks to the bigger magnetic energy compared with the single bulk. The presented results show that, on one hand, it is possible to estimate the total trapped magnetic flux of combined bulks by an approximate additive method of each single bulk while considering a demagnetization factor; on the other hand, it also means that the performance of combined bulks will be superior to the addition of each single bulk at larger gaps, thus preferable for large-scaled magnet applications.

  3. Behavioural divergence, interfertility and speciation: a review.

    Science.gov (United States)

    Pillay, Neville; Rymer, Tasmin L

    2012-11-01

    Behavioural compatibility between mates is fundamental for maintaining species boundaries and is achieved through appropriate communication between males and females. A breakdown in communication will lead to behavioural divergence and reduced interfertility. In this review, we summarise the current knowledge on male signals and female perception of these signals, integrating the literature from several taxa. We advocate that signaller-perceiver coevolution, which is usually under strong stabilising selection to enable mating, forms the basis of species-specific mate recognition systems. The mechanisms (phylogeny, geography, ecology, biology) shaping signaller-perceiver systems are briefly discussed to demonstrate the factors underpinning the evolution of signaller-perceiver couplings. Since divergence and diversification of communication systems is driven by changes in the mechanical properties of sensory pathways and morphology of sensory organs, we highlight signal modalities (auditory, olfactory, visual, tactile) and their importance in communication, particularly in mate selection. Next, using available examples and generating a stylised model, we suggest how disruption (biological, ecological, stochastic) of signaller-perceiver systems drives behavioural divergence and consequently results in reduced interfertility and speciation. Future studies should adopt an integrative approach, combining multiple parameters (phylogeny, adaptive utility of communication systems, genetics and biomechanical/biochemical properties of signals and perception) to explore how disruption of signaller-perceiver systems results in behavioural divergence and reduced interfertility. Finally, we question the impact that rapid environmental change will have on disruption of communication systems, potentially interfering with signaller-perceiver couplings. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Speciation of plutonium during sorption and diffusion in Opalinus clay

    International Nuclear Information System (INIS)

    Kaplan, Ugras

    2013-01-01

    well as on OPA thin sections and diffusion samples. Pu L III -edge EXAFS spectra of powder samples showed that an innersphere sorption of Pu(IV) species on OPA surface was formed, independent from the initial Pu oxidation states in solution. By combining the applied spatially resolved methods, it was possible for the first time to determine the elemental distribution of Pu and other elements contained in OPA using μ-XRF. Pu L III -edge μ-XANES spectra on Pu hot spots of thin sections and diffusion samples confirmed that less mobile Pu(IV) is the dominating species on OPA after sorption and diffusion processes. In addition, for the first time a diffusion profile of Pu in OPA was measured using μ-XRF. The speciation of Pu with μ-XANES showed that Pu(V) was reduced progressively along its diffusion path to Pu(IV). By μ-XRD the clay mineral illite was identified as the main mineral phase in areas where Pu was enriched and iron(II)-bearing siderite could be one of the redox-active mineral phases contained in OPA. The results of this work show that OPA is a suitable option for the geological disposal with regard to the safety of a nuclear repository.

  5. Guidelines for terms related to chemical speciations and fractionation of elements : definitions, structural aspects, and methodological approaches (IUPAC Recommendations 2000)

    NARCIS (Netherlands)

    Templeton, D.M.; Ariese, F.; Cornelis, R.; Danielsson, L.G.; Muntau, H.; Leeuwen, van H.P.; Lobínski, R.

    2000-01-01

    This paper presents definitions of concepts related to speciation of elements, more particularly speciation analysis and chemical species. Fractionation is distinguished from speciation analysis, and a general outline of fractionation procedures is given. We propose a categorization of species

  6. Particulate matter speciation profiles for light-duty gasoline vehicles in the United States.

    Science.gov (United States)

    Sonntag, Darrell B; Baldauf, Richard W; Yanca, Catherine A; Fulper, Carl R

    2014-05-01

    Representative profiles for particulate matter particles less than or equal to 2.5 microm (PM2.5) are developed from the Kansas City Light-Duty Vehicle Emissions Study for use in the US. Environmental Protection Agency (EPA) vehicle emission model, the Motor Vehicle Emission Simulator (MOVES), and for inclusion in the EPA SPECIATE database for speciation profiles. The profiles are compatible with the inputs of current photochemical air quality models, including the Community Multiscale Air Quality Aerosol Module Version 6 (AE6). The composition of light-duty gasoline PM2.5 emissions differs significantly between cold start and hot stabilized running emissions, and between older and newer vehicles, reflecting both impacts of aging/deterioration and changes in vehicle technology. Fleet-average PM2.5 profiles are estimated for cold start and hot stabilized running emission processes. Fleet-average profiles are calculated to include emissions from deteriorated high-emitting vehicles that are expected to continue to contribute disproportionately to the fleet-wide PM2.5 emissions into the future. The profiles are calculated using a weighted average of the PM2.5 composition according to the contribution of PM2.5 emissions from each class of vehicles in the on-road gasoline fleet in the Kansas City Metropolitan Statistical Area. The paper introduces methods to exclude insignificant measurements, correct for organic carbon positive artifact, and control for contamination from the testing infrastructure in developing speciation profiles. The uncertainty of the PM2.5 species fraction in each profile is quantified using sampling survey analysis methods. The primary use of the profiles is to develop PM2.5 emissions inventories for the United States, but the profiles may also be used in source apportionment, atmospheric modeling, and exposure assessment, and as a basis for light-duty gasoline emission profiles for countries with limited data. PM2.5 speciation profiles were

  7. XPS and EPXMA investigation and chemical speciation of aerosol samples formed in LWR core melting experiments

    International Nuclear Information System (INIS)

    Moers, H.; Jenett, H.; Kaufmann, R.; Klewe-Nebenius, H.; Pfennig, G.; Ache, H.J.

    1985-09-01

    Aerosol samples consisting of fission products and elements of light water reactor structural materials were collected during simulating in a laboratory scale the heat-up phase of a core melt accident. The aerosol particles were formed in a steam atmosphere at temperatures between 1200 and 1900 0 C of the melting charge. The investigation of the samples by use of X-ray photoelectron spectroscopy (XPS) permitted the chemical speciation of the detected aerosol constituents silver, cadmium, indium, tellurium, iodine, and cesium. A comparison of the elemental analysis results obtained from XPS with those achieved from electron probe X-ray micro analysis (EPXMA) revealed that aerosol particle surface and aerosol particle bulk are principally composed of the same elements and that these compositions vary with release temperature. In addition, quantitative differences between the composition of surface and bulk have only been observed for those aerosol samples which were collected at higher melting charge temperatures. In order to obtain direct information on chemical species below the surface selected samples were argon ion bombarded. Changes in composition and chemistry were monitored by XPS, and the results were interpreted in light of the effects, which were observed when appropriate standard samples were sputtered. (orig.) [de

  8. Analysis and speciation of the tritium in environmental matrices

    International Nuclear Information System (INIS)

    Bacchetta, Audrey

    2014-01-01

    This study deals with environmental monitoring. The main aims are (i) the optimisation of the analytical procedure for the tritium in organic form determination, and (ii) the identification of the tritium bearing molecules which are responsible for its transfer from the environment to man. The study was divided into three stages. First an analytical method was developed to determine hydrogen content of several samples, which is a key element to calculate accurate organically bound tritium activities. Secondly, the impact of the organically bound tritium fractions separation (labile exchange) for the determination of the representative fraction of the level of environmental tritium activity was then evaluated. For that, the amount of solubilised sample was estimated. Finally, the speciation of tritium in environmental samples was investigated. Several molecules classes and organic compounds dissolved in the labile exchanges solvent were identified. The results show that the distribution of tritium in organisms depends on both properties of the chemical bond in which it is involved and chemical properties of tritium bearing molecules. The identified compounds belong to the molecules classes such as carbohydrates or amino acids, constitutive of living organisms. It would now be of interest to study the tritium distribution in an environmental sample to target molecules of interest and study the impact of tritium from the environment to man. (author) [fr

  9. Speciation of cadmium mixed ligand complexes in salt water lakes

    Directory of Open Access Journals (Sweden)

    John L. Kituyi

    2003-06-01

    Full Text Available Amalgam voltammetry has been used to study heavy metal interaction in model lake water in KNO3 at 23 oC at concentration levels of genuine lake water. The hanging drop amalgam electrode was prepared in situ before exchanging the medium for the sample solution. Half-wave potentials at two metal ion concentrations were measured, one at the actual concentration in the lake while the other at a much lower one. The experimentally determined shifts in half-wave potentials are used to compute several formation constants. At the natural [CO32-] of 0.5 M in the lake, the main contributor to the speciation of cadmium is [Cd(CO3Cl2]2-. At high [Cd2+], the DPASV detects the presence of free Cd2+ ions, hence, potential polluting effect, while the amalgam reports [Cd(CO32Cl] 3- to be dominant above [CO32-] = 0.8 M. There is a variation in the number of complexes detected, their stabilities and percentage distribution in the two methods. Cd2+ ion concentration also affects the number of complexes formed and their stabilities.

  10. NEARSOL, Aqueous Speciation and Solubility of Actinides for Waste Disposal

    International Nuclear Information System (INIS)

    Leach, S.J.; Pryke, D.C.

    1989-01-01

    A - Description of program or function: NEARSOL models the aqueous speciation and solubility of actinides under near-field conditions for disposal using a simple thermodynamic approach. B - Method of solution: The program draws information from a thermodynamic data base consisting of solubility products and complex formation constants for all known species, and standard electrode potentials, at 25 C, corrected for ionic strength effects. By minimising the free energy of the system through a series of iterations, a precipitating solid phase is predicted which limits the solubility, and the concentration of the main aqueous species are calculated as a function of pH. Initially the program evaluates only hydroxide and carbonate species, but the effect of sulphate, phosphate and fluoride anions can also be included. The program is simple to use, requiring inputs of: 1. Actinide(s); 2. pH range; 3. Ionic strength; 4. Redox conditions; 5. Ligand concentrations. Functions are included to calculate the distribution of the protonated and un-protonated forms of carbonate and phosphate and the value of Eh as a function of pH under disposal conditions as required. The program can further evaluate the role of free calcium ions. C - Restrictions on the complexity of the problem: None

  11. Arsenic, Antimony, Chromium, and Thallium Speciation in Water and Sediment Samples with the LC-ICP-MS Technique

    Directory of Open Access Journals (Sweden)

    Magdalena Jabłońska-Czapla

    2015-01-01

    Full Text Available Chemical speciation is a very important subject in the environmental protection, toxicology, and chemical analytics due to the fact that toxicity, availability, and reactivity of trace elements depend on the chemical forms in which these elements occur. Research on low analyte levels, particularly in complex matrix samples, requires more and more advanced and sophisticated analytical methods and techniques. The latest trends in this field concern the so-called hyphenated techniques. Arsenic, antimony, chromium, and (underestimated thallium attract the closest attention of toxicologists and analysts. The properties of those elements depend on the oxidation state in which they occur. The aim of the following paper is to answer the question why the speciation analytics is so important. The paper also provides numerous examples of the hyphenated technique usage (e.g., the LC-ICP-MS application in the speciation analysis of chromium, antimony, arsenic, or thallium in water and bottom sediment samples. An important issue addressed is the preparation of environmental samples for speciation analysis.

  12. Ordered bulk degradation via autophagy

    DEFF Research Database (Denmark)

    Dengjel, Jörn; Kristensen, Anders Riis; Andersen, Jens S

    2008-01-01

    During amino acid starvation, cells undergo macroautophagy which is regarded as an unspecific bulk degradation process. Lately, more and more organelle-specific autophagy subtypes such as reticulophagy, mitophagy and ribophagy have been described and it could be shown, depending on the experimental...... at proteasomal and lysosomal degradation ample cross-talk between the two degradation pathways became evident. Degradation via autophagy appeared to be ordered and regulated at the protein complex/organelle level. This raises several important questions such as: can macroautophagy itself be specific and what...

  13. Speciation fingerprints of binary mixtures by the optimized sequential two-phase separation

    International Nuclear Information System (INIS)

    Macasek, F.

    1995-01-01

    The analysis of the separation methods suitable for chemical speciation of radionuclides and metals, and advantages of sequential (double) distribution technique were discussed. The equilibria are relatively easy to control and the method enables to minimize a matrix composition adjustment, and therefore it minimizes also the disturbance of original (native) state of elements. The technique may consist in the repeat solvent extraction of sample, or the replicate equilibration with sorbent. The common condition of applicability is a linear separation isotherm of the species, what is mostly a reasonable condition in case of trace concentrations. The equations used for simultaneous fitting were written in general form. 1 tab., 1 fig., 2 refs

  14. Speciation analysis of 129I and its applications in environmental research

    DEFF Research Database (Denmark)

    Zhang, Luyuan; Hou, Xiaolin

    2013-01-01

    129I, a long-lived radionuclide, is important in view of geological repository of nuclear waste, and environmental tracing applications related to diverse natural processes of iodine. The environmental behaviors and bioavailability of 129I are highly related to its species. A number of methods have...... been reported for speciation analysis of 129I in a variety of environmental samples. These methods have been applied in many researches, including conversion processes of iodine species in marine and terrestrial systems, migration and retention of iodine in soil and sediment, geochemical cycling...

  15. Chemical speciation analysis and environmental behaviour of 127I and 12

    International Nuclear Information System (INIS)

    Hansen, Violeta

    2011-10-01

    showed a lower adsorption capacity of inorganic and organic iodine species. Adsorption of iodine species onto activated charcoal and DEAE 32 cellulose from seawater samples shows that only about 10% of the total iodine in seawater can be adsorbed onto those materials. Adsorption of iodine species from water samples onto activated charcoal/DEAE is not a suitable method for quantifying the total iodine in freshwater and seawater. An investigation was conducted in order to decompose organic iodine using K 2 S 2 O 8 in water samples for developing a method for quantification of aquatic organic iodine ( 129 I and 127 I). The results show that iodine was quantitatively removed even when the concentration of organic iodine compounds in the studied sample was very high. Due to this, oxidation of iodine organic matter by using K 2 S 2 O 8 followed by reduction of iodine species and precipitation with silver can be a potential method for determination of total iodine in fresh water samples. An improvement was made of the method for 129 I and 127 I speciation analysis in soil and sediment samples involving the extraction and fractionation of organic matter. The improved method was further used for the partitioning of 127 I and 129 I in marine sediments and soils. Sequential extraction results point out that partitioning of 127 I and 129 I within the organic fraction in soil and marine sediments is controlled by pH conditions where pH values below 5.0-5.5 promote occurrence of 127 I and 129 I in the humic acid, while at pH > 6 the partitioning was in the fulvic acid fraction. Anoxic conditions seemed to increase the mobility and availability of iodine compared to oxic, while suboxic conditions (soils) reduced the availability of the water soluble fraction compared to the subaqueous (marine) one. The distribution of 129 I/ 127 I values differed significantly between phases and samples, indicating that equilibrium with stable iodine have not yet been reached for a large fraction of

  16. Genomics of Rapid Incipient Speciation in Sympatric Threespine Stickleback.

    Directory of Open Access Journals (Sweden)

    David A Marques

    2016-02-01

    Full Text Available Ecological speciation is the process by which reproductively isolated populations emerge as a consequence of divergent natural or ecologically-mediated sexual selection. Most genomic studies of ecological speciation have investigated allopatric populations, making it difficult to infer reproductive isolation. The few studies on sympatric ecotypes have focused on advanced stages of the speciation process after thousands of generations of divergence. As a consequence, we still do not know what genomic signatures of the early onset of ecological speciation look like. Here, we examined genomic differentiation among migratory lake and resident stream ecotypes of threespine stickleback reproducing in sympatry in one stream, and in parapatry in another stream. Importantly, these ecotypes started diverging less than 150 years ago. We obtained 34,756 SNPs with restriction-site associated DNA sequencing and identified genomic islands of differentiation using a Hidden Markov Model approach. Consistent with incipient ecological speciation, we found significant genomic differentiation between ecotypes both in sympatry and parapatry. Of 19 islands of differentiation resisting gene flow in sympatry, all were also differentiated in parapatry and were thus likely driven by divergent selection among habitats. These islands clustered in quantitative trait loci controlling divergent traits among the ecotypes, many of them concentrated in one region with low to intermediate recombination. Our findings suggest that adaptive genomic differentiation at many genetic loci can arise and persist in sympatry at the very early stage of ecotype divergence, and that the genomic architecture of adaptation may facilitate this.

  17. Pollinator-Driven Speciation in Sexually Deceptive Orchids

    Directory of Open Access Journals (Sweden)

    Shuqing Xu

    2012-01-01

    Full Text Available Pollinator-mediated selection has been suggested to play a major role for the origin and maintenance of the species diversity in orchids. Sexually deceptive orchids are one of the prime examples for rapid, pollinator-mediated plant radiations, with many species showing little genetic differentiation, lack of postzygotic barriers, but strong prezygotic reproductive isolation. These orchids mimic mating signals of female insects and employ male insects as pollinators. This kind of sexual mimicry leads to highly specialised pollination and provides a good system for investigating the process of pollinator-driven speciation. Here, we summarise the knowledge of key processes of speciation in this group of orchids and conduct a meta-analysis on traits that contribute to species differentiation, and thus potentially to speciation. Our study suggests that pollinator shift through changes in floral scent is predominant among closely related species in sexually deceptive orchids. Such shifts can provide a mechanism for pollinator-driven speciation in plants, if the resulting floral isolation is strong. Furthermore, changes in floral scent in these orchids are likely controlled by few genes. Together these factors suggest speciation in sexually deceptive orchids may happen rapidly and even in sympatry, which may explain the remarkable species diversity observed in this plant group.

  18. Speciation and Health Risks of Atmospheric Nanoparticulates

    Science.gov (United States)

    Nguyen, Kennedy

    Exposure to air pollution causes several adverse health effects such as asthma, respiratory disease, cardiovascular disease, cancer, and premature death; and the San Joaquin Valley is one of the most heavily polluted regions in the US. The mountains that surround the valley allow air pollution, including particulate matter, to remain stagnant, prolonging the exposure of valley populations to it. The primary sources of particulate matter for this region are aluminosilicate dust from agricultural activities, and soot emissions from diesel trucks and vehicular traffic. A substantial fraction of emitted material is nanoparticulate matter (testing in cell culture studies, and correlation of particulate properties and sources with their negative health impacts. These results can help identify the sources of air pollution to prioritize for mitigation for the greatest health benefit. In addition, further chemical speciation can help monitor the results of such mitigation efforts. Here, natural particulate matter samples from Merced and Fresno, two cities in the San Joaquin Valley, were analyzed. Ultrafine particles present were 40 to 50 nm in diameter and mostly composed of aluminum, silicon, oxygen, and iron hydroxide. XAS data confirmed the presence of the aluminosilicate as smectite clay and the iron hydroxide as ferrihydrite. Furthermore, a chemical speciation study investigated industrial emissions of air particulate matter. Samples were analyzed using electron microscopy for elemental composition and size distribution, and found to contain fine metal particulates (lead and iron) that can lead to lung inflammation. From characterization data, in order to create a simplified proxy particle system for cell culture studies, amorphous silica particles were synthesized using a modified Stober Synthesis and coated with iron hydroxide. A range of iron hydroxide concentrations (0.06 to 1.63 mmol of iron per gram of silica) were used to test the effect of iron contamination on

  19. Study of Np speciation in citrate medium

    Energy Technology Data Exchange (ETDEWEB)

    Bonin, L.; Den Auwer, C.; Ansoborlo, E.; Moisy, P. [CEA Valrho - DEN/DRCP/SCPS, Bagnols sur Ceze (France); Cote, G. [ENSP - LECA, UMR 7575, Paris (France)

    2007-07-01

    In the framework of the French Environmental Nuclear Toxicology program, additional experiments related to the decorporation of actinides are planned. Decorporation is the removal or release from target organs (bones, liver, kidney..), tissues or cells of radioactive material previously incorporated in them, using chelating agents or other administrated pharmaceutical agents. The contradictory data on the neptunium complexation behaviour within blood and its transfer to target organs, as well as the inefficiency of therapeutic treatments, led us to study the complexation of this element with biological constituents. Within this purpose, the in vitro behaviour of Np(IV) and Np(V) in simple media simulating biological fluids was studied. This study was more specifically focused on the behaviour of neptunium with citrate ion, which is an essential component in a number of metalloenzyme active sites. In order to determine the speciation of this system, spectrophotometry was more particularly used. Concerning the complexation phenomenon, the existence of several complexes of Np(V) with various acido-basic forms of the citrate anion was observed; regarding Np(IV), complexes with Cit{sup 3-} have been observed. From the quantitative study of these equilibria, the values of the absolute constants for the complexation of Np(IV) and Np(V) with citrate were determined. Concerning the stability of neptunium towards oxydo-reduction, it was confirmed that Np(VI) was very quickly reduced to Np(V) by the citrate anions, whereas Np(IV) was stable. In the case of Np(V), it was observed that, depending on the pH and the citrate concentration, Np(V) was unstable and was reduced to Np(IV). The E-pH diagrams, constructed using the stability constants determined in this study, showed that this instability was due to the Np(V) disproportionation. (orig.)

  20. Voltammetric Investigation Of Hydrothermal Iron Speciation

    Directory of Open Access Journals (Sweden)

    Charlotte eKleint

    2016-05-01

    Full Text Available Hydrothermal vent fluids are highly enriched in iron (Fe compared to ambient seawater, and organic ligands may play a role in facilitating the transport of some hydrothermal Fe into the open ocean. This is important since Fe is a limiting micronutrient for primary production in large parts of the world`s surface ocean. We have investigated the concentration and speciation of Fe in several vent fluid and plume samples from the Nifonea vent field, Coriolis Troughs, New Hebrides Island Arc, South Pacific Ocean using competitive ligand exchange - adsorptive cathodic stripping voltammetry (CLE - AdCSV with salicylaldoxime (SA as the artificial ligand. Our results for total dissolved Fe (dFe in the buoyant hydrothermal plume samples showed concentrations up to 3.86 µM dFe with only a small fraction between 1.1% and 11.8% being chemically labile. Iron binding ligand concentrations ([L] were found in µM level with strong conditional stability constants up to log K[L],Fe3+ of 22.9. Within the non-buoyant hydrothermal plume above the Nifonea vent field, up to 84.7% of the available Fe is chemically labile and [L] concentrations up to 97 nM were measured. [L] was consistently in excess of Felab, indicating that all available Fe is being complexed, which in combination with high Felab values in the non-buoyant plume, signifies that a high fraction of hydrothermal dFe is potentially being transported away from the plume into the surrounding waters, contributing to the global oceanic Fe budget.

  1. Determination of Tolterodine tartrate in bulk and formulation by ...

    African Journals Online (AJOL)

    Purpose: To develop a new simple, accurate, precise and fully validated extractive colorimetric method for the determination of tolterodine tartrate (TL) in bulk and in tablet dosage form, Method: A chloroform extractable orange red complex formed between the acid dye, tropaeolin OOO-1 and tolterodine in acid media is the ...

  2. A modelling exercise on the importance of ternary alkaline earth carbonate species of uranium(VI) in the inorganic speciation of natural waters

    International Nuclear Information System (INIS)

    Vercouter, Thomas; Reiller, Pascal E.; Ansoborlo, Eric; Février, Laureline; Gilbin, Rodolphe; Lomenech, Claire; Philippini, Violaine

    2015-01-01

    Highlights: • The U(VI) speciation in natural waters has been modelled through a modelling exercise. • The results evidence the importance of alkaline earth U(VI) carbonate complexes. • Possible solubility-controlling phases were reported and discussed. • The differences were related to the choice and reliability of thermodynamic data. • Databases need to be improved for reliable U(VI) speciation calculations. - Abstract: Predictive modelling of uranium speciation in natural waters can be achieved using equilibrium thermodynamic data and adequate speciation software. The reliability of such calculations is highly dependent on the equilibrium reactions that are considered as entry data, and the values chosen for the equilibrium constants. The working group “Speciation” of the CETAMA (Analytical methods establishment committee of the French Atomic Energy commission, CEA) has organized a modelling exercise, including four participants, in order to compare modellers’ selections of data and test thermodynamic data bases regarding the calculation of U(VI) inorganic speciation. Six different compositions of model waters were chosen so that to check the importance of ternary alkaline earth carbonate species of U(VI) on the aqueous speciation, and the possible uranium solid phases as solubility-limiting phases. The comparison of the results from the participants suggests (i) that it would be highly valuable for end-users to review thermodynamic constants of ternary carbonate species of U(VI) in a consistent way and implement them in available speciation data bases, and (ii) stresses the necessary care when using data bases to avoid biases and possible erroneous calculations

  3. Microhardness of bulk-fill composite materials

    OpenAIRE

    Kelić, Katarina; Matić, Sanja; Marović, Danijela; Klarić, Eva; Tarle, Zrinka

    2016-01-01

    The aim of the study was to determine microhardness of high- and low-viscosity bulk-fill composite resins and compare it with conventional composite materials. Four materials of high-viscosity were tested, including three bulk-fills: QuiXfi l (QF), x-tra fil (XTF) and Tetric EvoCeram Bulk Fill (TEBCF), while nanohybrid composite GrandioSO (GSO) served as control. The other four were low-viscosity composites, three bulk-fill materials: Smart Dentin Replacement (SDR), Venus Bulk Fill (VBF) and ...

  4. Handling of bulk solids theory and practice

    CERN Document Server

    Shamlou, P A

    1990-01-01

    Handling of Bulk Solids provides a comprehensive discussion of the field of solids flow and handling in the process industries. Presentation of the subject follows classical lines of separate discussions for each topic, so each chapter is self-contained and can be read on its own. Topics discussed include bulk solids flow and handling properties; pressure profiles in bulk solids storage vessels; the design of storage silos for reliable discharge of bulk materials; gravity flow of particulate materials from storage vessels; pneumatic transportation of bulk solids; and the hazards of solid-mater

  5. Simultaneous speciation of trace elements using chemical separation and neutron activation

    International Nuclear Information System (INIS)

    Chatt, A.

    2003-01-01

    Speciation neutron activation analysis (SNAA) is a sophisticated analytical technique which can be developed for studying the simultaneous speciation of a number of elements in a variety of matrices. The advantages of SNAA are demonstrated with typical examples such as (i) arsenic speciation in sea foods and water, and simultaneous speciation of (ii) arsenic, antimony and selenium in water, (iii) chlorine, bromine and iodine in fish, (iv) lanthanides in simulated vitrified waste, and (v) trace elements bound to proteins. (author)

  6. ISSEBETS 2009. 7. International Symposium on Speciation of Elements in Biological, Environmental and Toxicological Sciences

    International Nuclear Information System (INIS)

    2009-01-01

    The 7th ISSEBETS was held in August 2009 in city of Eger, Hungary. The main topics were: speciation of essential and toxic elements in food, in traditional drugs, designing functional foods through applied speciation, metallomics and metalloproteomics, metal species in health and disease, cycling of elemental species in the environment, speciation related regulations and legislation, metal environmental, bioremediation, quality assurance of speciation analysis. (S.I.)

  7. Evolution of uranium distribution and speciation in mill tailings, COMINAK Mine, Niger

    International Nuclear Information System (INIS)

    Déjeant, Adrien; Galoisy, Laurence; Roy, Régis; Calas, Georges; Boekhout, Flora; Phrommavanh, Vannapha; Descostes, Michael

    2016-01-01

    This study investigated the evolution of uranium distribution and speciation in mill tailings from the COMINAK mine (Niger), in production since 1978. A multi-scale approach was used, which combined high resolution remote sensing imagery, ICP-MS bulk rock analyses, powder X-ray diffraction, Scanning Electron Microscopy, Focused Ion Beam — Transmission Electron Microscopy and X-ray Absorption Near Edge Spectroscopy. Mineralogical analyses showed that some ore minerals, including residual uraninite and coffinite, undergo alteration and dissolution during tailings storage. The migration of uranium and other contaminants depends on (i) the chemical stability of secondary phases and sorbed species (dissolution and desorption processes), and (ii) the mechanical transport of fine particles bearing these elements. Uranium is stabilized after formation of secondary uranyl sulfates and phosphates, and adsorbed complexes on mineral surfaces (e.g. clay minerals). In particular, the stock of insoluble uranyl phosphates increases with time, thus contributing to the long-term stabilization of uranium. At the surface, a sulfate-cemented duricrust is formed after evaporation of pore water. This duricrust limits water infiltration and dust aerial dispersion, though it is enriched in uranium and many other elements, because of pore water rising from underlying levels by capillary action. Satellite images provided a detailed description of the tailings pile over time and allow monitoring of the chronology of successive tailings deposits. Satellite images suggest that uranium anomalies that occur at deep levels in the pile are most likely former surface duricrusts that have been buried under more recent tailings. - Highlights: • The evolution of U distribution and speciation in mill tailings is investigated. • High resolution satellite images provide useful information on tailings evolution. • U and many other elements are enriched in a sulfate-rich duricrust. • Formation of

  8. Evolution of uranium distribution and speciation in mill tailings, COMINAK Mine, Niger

    Energy Technology Data Exchange (ETDEWEB)

    Déjeant, Adrien, E-mail: adrien.dejeant@normalesup.org [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Case 115, 4 place Jussieu, 75005 Paris (France); Université Paris Diderot — Paris VII, 5 rue Thomas Mann, 75013 Paris (France); Galoisy, Laurence [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Case 115, 4 place Jussieu, 75005 Paris (France); Université Pierre et Marie Curie — Paris VI, 4 place Jussieu, 75005 Paris (France); Roy, Régis [AREVA Mines — Geoscience Department, Tour AREVA, 1 place Jean Millier, 92084 Paris, La Défense (France); Calas, Georges; Boekhout, Flora [Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie, Case 115, 4 place Jussieu, 75005 Paris (France); Université Pierre et Marie Curie — Paris VI, 4 place Jussieu, 75005 Paris (France); Phrommavanh, Vannapha; Descostes, Michael [AREVA Mines — R& D Department, BAL 0414C-2, Tour AREVA, 1 place Jean Millier, 92084 Paris, La Défense (France)

    2016-03-01

    This study investigated the evolution of uranium distribution and speciation in mill tailings from the COMINAK mine (Niger), in production since 1978. A multi-scale approach was used, which combined high resolution remote sensing imagery, ICP-MS bulk rock analyses, powder X-ray diffraction, Scanning Electron Microscopy, Focused Ion Beam — Transmission Electron Microscopy and X-ray Absorption Near Edge Spectroscopy. Mineralogical analyses showed that some ore minerals, including residual uraninite and coffinite, undergo alteration and dissolution during tailings storage. The migration of uranium and other contaminants depends on (i) the chemical stability of secondary phases and sorbed species (dissolution and desorption processes), and (ii) the mechanical transport of fine particles bearing these elements. Uranium is stabilized after formation of secondary uranyl sulfates and phosphates, and adsorbed complexes on mineral surfaces (e.g. clay minerals). In particular, the stock of insoluble uranyl phosphates increases with time, thus contributing to the long-term stabilization of uranium. At the surface, a sulfate-cemented duricrust is formed after evaporation of pore water. This duricrust limits water infiltration and dust aerial dispersion, though it is enriched in uranium and many other elements, because of pore water rising from underlying levels by capillary action. Satellite images provided a detailed description of the tailings pile over time and allow monitoring of the chronology of successive tailings deposits. Satellite images suggest that uranium anomalies that occur at deep levels in the pile are most likely former surface duricrusts that have been buried under more recent tailings. - Highlights: • The evolution of U distribution and speciation in mill tailings is investigated. • High resolution satellite images provide useful information on tailings evolution. • U and many other elements are enriched in a sulfate-rich duricrust. • Formation of

  9. Speciation of phosphorus in the continental shelf sediments in the Eastern Arabian Sea

    Science.gov (United States)

    Acharya, Shiba Shankar; Panigrahi, Mruganka Kumar; Kurian, John; Gupta, Anil Kumar; Tripathy, Subhasish

    2016-03-01

    The distributions of various forms of phosphorus (P) and their relation with sediment geochemistry in two core sediments near Karwar and Mangalore offshore have been studied through the modified SEDEX procedure (Ruttenberg et al., 2009) and bulk chemical analysis. The present study provides the first quantitative analysis of complete phosphorus speciation in the core sediments of the Eastern Arabian shelf. The chemical index of alteration (CIA), chemical Index of Weathering (CIW) and Al-Ti-Zr ternary diagram suggest low to moderate source area weathering of granodioritic to tonalitic source rock composition, despite the intense orographic rainfall in the source area. Due to the presence of same source rock and identical oxic depositional environment, the studied sediments show the same range of variation of total phosphorus (24 to 83 μmol/g) with a down-depth depleting trend. Organic bound P and detrital P are the two major chemical forms followed by iron-bound P, exchangeable/loosely bound P and authigenic P. The authigenic P content in the sediments near Mangalore coast varies linearly with calcium (r=0.88) unlike that of Karwar coast. The different reactive-phosphorus pools exhibit identical depleting trend with depth. This indicates that the phosphorus released from the organic matter and Fe bound fractions are prevented from precipitating as authigenic phosphates in the deeper parts of the sediment column. The low concentration of total P, dominance of detrital non-reactive fraction of P and inhibition of formation of authigenic phosphate result in the absence of active phosphatization in the Eastern Arabian Shelf in the studied region. High sedimentation rate (35-58 cm/kyr) and absence of winnowing effect appear to be the dominant factor controlling the P-speciation in the studied sediments.

  10. Patterns of plant speciation in the Cape floristic region.

    Science.gov (United States)

    van der Niet, Timotheüs; Johnson, Steven D

    2009-04-01

    Plant species have accumulated in the Cape region of southern Africa to a much greater degree than in areas of equivalent size in the rest of the subcontinent. Although this could be a consequence simply of lower extinction rates in the Cape, most researchers have invoked high rates of ecological speciation, driven by unique aspects of the Cape environment, as the primary explanation for this richness. To assess these ideas, we analyzed the frequencies of ecological shifts among 188 sister species pairs obtained from molecular phylogenies of eight Cape clades. Ecological shifts were evident in 80% of sister species pairs, with general habitat, pollinator, and fire-survival strategy shifts being especially frequent. Contrary to an established idea that shifts in soil type are frequently associated with speciation of Cape taxa, these shifts were relatively rare, occurring in just 17% of species pairs. More cases of sister species divergence are accompanied solely by floral than by vegetative diversification, suggesting an important role for pollinator-driven speciation. In an analysis of two large orchid genera that have radiated in both the Cape and the rest of southern Africa, the frequency of ecological shifts (general habitat, soil type, altitude and flowering time), did not differ between sister species pairs in the Cape region and those outside it. Despite suggestions that Cape plants tend to have small range sizes and show fine-scale patterns of speciation, range size did not differ significantly between species in the Cape and those outside it. We conclude that ecological speciation is likely to have been important for radiation of the Cape flora, but there is no evidence as yet for special "Cape" patterns of ecological speciation.

  11. Towards accounting for dissolved iron speciation in global ocean models

    Directory of Open Access Journals (Sweden)

    A. Tagliabue

    2011-10-01

    Full Text Available The trace metal iron (Fe is now routinely included in state-of-the-art ocean general circulation and biogeochemistry models (OGCBMs because of its key role as a limiting nutrient in regions of the world ocean important for carbon cycling and air-sea CO2 exchange. However, the complexities of the seawater Fe cycle, which impact its speciation and bioavailability, are simplified in such OGCBMs due to gaps in understanding and to avoid high computational costs. In a similar fashion to inorganic carbon speciation, we outline a means by which the complex speciation of Fe can be included in global OGCBMs in a reasonably cost-effective manner. We construct an Fe speciation model based on hypothesised relationships between rate constants and environmental variables (temperature, light, oxygen, pH, salinity and assumptions regarding the binding strengths of Fe complexing organic ligands and test hypotheses regarding their distributions. As a result, we find that the global distribution of different Fe species is tightly controlled by spatio-temporal environmental variability and the distribution of Fe binding ligands. Impacts on bioavailable Fe are highly sensitive to assumptions regarding which Fe species are bioavailable and how those species vary in space and time. When forced by representations of future ocean circulation and climate we find large changes to the speciation of Fe governed by pH mediated changes to redox kinetics. We speculate that these changes may exert selective pressure on phytoplankton Fe uptake strategies in the future ocean. In future work, more information on the sources and sinks of ocean Fe ligands, their bioavailability, the cycling of colloidal Fe species and kinetics of Fe-surface coordination reactions would be invaluable. We hope our modeling approach can provide a means by which new observations of Fe speciation can be tested against hypotheses of the processes present in governing the ocean Fe cycle in an

  12. Composition of COH fluids at 1 GPa: an experimental study on speciation and solubility

    Science.gov (United States)

    Tiraboschi, Carla; Tumiati, Simone; Recchia, Sandro; Ulmer, Peter; Pettke, Thomas; Fumagalli, Patrizia; Poli, Stefano

    2014-05-01

    convoying evolved gases to a QMS through a heated line to avoid the condensation of water. This type of analyzer ensures superior performances in terms of selectivity of molecules to be detected, high acquisition rates and extended linear response range. The influence of dissolved solutes on fluid speciation has been evaluated by comparing experiments in the pure COH system and in the COH+forsterite system. To determine the solubility of forsterite in COH fluids we performed a second set of experiments at the same P , T and fO2 conditions above. Fluids trapped in a diamond layer were analysed by the cryogenic LA-ICP-MS technique described by Aerts et al. (2010). With this method the aqueous part of the COH fluid is frozen prior the opening and maintained frozen during the analysis to avoid any precipitation of solutes. The results will highlight the importance of fluids for the mass transport in subduction zones. Comparison between experimental data and thermodynamic calculation will also be shown. References: Aerts, M., Hack, A.C., Reusser, E., Ulmer, P. (2010) Am. Mineral. 95, 1523-1526. Newton, R.C., Manning, C.E. (2002) Geochim. Cosmochim. Ac. 66, 4165-4176.

  13. High temperature superconductor bulk materials. Fundamentals - processing - properties control - application aspects

    International Nuclear Information System (INIS)

    Krabbes, G.; Fuchs, G.; Canders, W.R.; May, H.; Palka, R.

    2006-01-01

    This book presents all the features of bulk high temperature superconducting materials. Starting from physical and chemical fundamentals, the authors move on to portray methods and problems of materials processing, thoroughly working out the characteristic properties of bulk superconductors in contrast to long conductors and films. The authors provide a wide range of specific materials characteristics with respect to the latest developments and future applications guiding from fundamentals to practical engineering examples. This book contains the following chapters: 1. Fundamentals 2. Growth and melt processing of YBCO 3. Pinning-relevant defects in bulk YBCO 4. Properties of bulk YBCO 5. Trapped fields 6. Improved YBCO based bulk superconductors and functional elements 7. Alternative systems 8. Peak effect 9. Very high trapped fields in YBCO permanent magnets 10. Engineering aspects: Field distribution in bulk HTSC 11. Inherently stable superconducting magnetic bearings 12. Application of bulk HTSCs in electromagnetic energy converters 13. Applications in magnet technologies and power supplies

  14. Simultaneous Speciation of Arsenic, Selenium, and Chromium by HPLC-ICP-MS

    Science.gov (United States)

    Wolf, Ruth E.; Morman, Suzette A.; Morrison, Jean M.; Lamothe, Paul J.

    2008-01-01

    An adaptation of an analytical method developed for chromium speciation has been utilized for the simultaneous determination of As(III), As(V), Se(IV), Se(VI), Cr(III), and Cr(VI) species using high performance liquid chromatography (HPLC) separation with ICP-MS detection. Reduction of interferences for the determination of As, Se, and Cr by ICP-MS is a major consideration for this method. Toward this end, a Dynamic Reaction Cell (DRC) ICP-MS system was used to detect the species eluted from the chromatographic column. A variety of reaction cell gases and conditions may be utilized, and the advantages and limitations of the gases tested to date will be presented and discussed. The separation and detection of the As, Se, and Cr species of interest can be achieved using the same chromatographic conditions in less than 2 minutes by complexing the Cr(III) with EDTA prior to injection on the HPLC column. Practical aspects of simultaneous speciation analysis will be presented and discussed, including issues with HPLC sample vial contamination, standard and sample contamination, species stability, and considerations regarding sample collection and preservation methods. The results of testing to determine the method's robustness to common concomitant element and anion effects will also be discussed. Finally, results will be presented using the method for the analysis of a variety of environmental and geological samples including waters, soil leachates and simulated bio-fluid leachates.

  15. Bulk handling benefits from ICT

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2007-11-15

    The efficiency and accuracy of bulk handling is being improved by the range of management information systems and services available today. As part of the program to extend Richards Bay Coal Terminal, Siemens is installing a manufacturing execution system which coordinates and monitors all movements of raw materials. The article also reports recent developments by AXSMarine, SunGuard Energy, Fuelworx and Railworx in providing integrated tools for tracking, managing and optimising solid/liquid fuels and rail car maintenance activities. QMASTOR Ltd. has secured a contract with Anglo Coal Australia to provide its Pit to Port.net{reg_sign} and iFuse{reg_sign} software systems across all their Australians sites, to include pit-to-product stockpile management. 2 figs.

  16. Bulk analysis using nuclear techniques

    International Nuclear Information System (INIS)

    Borsaru, M.; Holmes, R.J.; Mathew, P.J.

    1983-01-01

    Bulk analysis techniques developed for the mining industry are reviewed. Using penetrating neutron and #betta#-radiations, measurements are obtained directly from a large volume of sample (3-30 kg) #betta#-techniques were used to determine the grade of iron ore and to detect shale on conveyor belts. Thermal neutron irradiation was developed for the simultaneous determination of iron and aluminium in iron ore on a conveyor belt. Thermal-neutron activation analysis includes the determination of alumina in bauxite, and manganese and alumina in manganese ore. Fast neutron activation analysis is used to determine silicon in iron ores, and alumina and silica in bauxite. Fast and thermal neutron activation has been used to determine the soil in shredded sugar cane. (U.K.)

  17. Efficient Bulk Operations on Dynamic R-Trees

    DEFF Research Database (Denmark)

    Arge, Lars Allan; Hinrichs, Klaus; Vahrenhold, Jan

    2002-01-01

    In recent years there has been an upsurge of interest in spatial databases. A major issue is how to manipulate efficiently massive amounts of spatial data stored on disk in multidimensional spatial indexes (data structures). Construction of spatial indexes (bulk loading ) has been studied...... intensively in the database community. The continuous arrival of massive amounts of new data makes it important to update existing indexes (bulk updating ) efficiently. In this paper we present a simple, yet efficient, technique for performing bulk update and query operations on multidimensional indexes. We...... present our technique in terms of the so-called R-tree and its variants, as they have emerged as practically efficient indexing methods for spatial data. Our method uses ideas from the buffer tree lazy buffering technique and fully utilizes the available internal memory and the page size of the operating...

  18. Speciation of phosphorus in Lake Dang of Ngaoundere-Cameroon.

    Science.gov (United States)

    Bertrand, Noumi Guy; Marie, Sieliechi Joseph; Fidèle, Fabane; Jean-Marie, Dangwang Dikdim

    2015-02-01

    In this study, we investigated the nature of phosphate phase present in sediment of Lake Dang. The phosphate speciation was determined by sequential extraction method. The concentration of phosphate in solution was measured by the ammonium molybdate method with ascorbic acid as the reducing agent. Water and sediment (surface and bottom) were sampled at eight points around the lake by taking into account activities around the lake during dry and rainy seasons. The results showed five forms of phosphorus presents in the sediments. The rank order obtained was Res-P phosphorus (P-L + P-Ca + P-Fe) than organic phase. The average phosphorus (P) content was 133, 86, and 52 μg g(-1) for the surface layer (A, 0-5 cm), medium layer (B, 5-10 cm), and bottom layer (C, 10-15 cm), respectively. This P-content depletion with depth can be explained mainly by oxygen depletion with depth which enhance P desorption. Except P-L form, the P contents were higher in rainy season compared to the dry season. The results of principal component analysis indicate that inorganic phosphorus (P-L + P-Ca + P-Fe) were linked and were provided mainly by car-washing. It appears clearly that phosphorus content vary significantly during the seasons. These results showed also that the amount of (P-Fe) is higher than the others whatever the season. This P form is easily labile and bioavailable which suggest that it can unfortunately enhance greatly the eutrophication of Lake Dang.

  19. Chemical Speciation of Long-lived Radionuclide Technetium-99 and its Environmental Behaviour

    DEFF Research Database (Denmark)

    Shi, Keliang

    issue for understanding its fate and behaviour in ecosystem. This thesis aims to develop series of analytical methods for rapid and accurate determination of total 99Tc in environmental samples (e.g., seaweed, soil, and seawater), as well as speciation analysis of 99Tc in seaweeds. The application of 99...... - sorption at different concentrations of H+ was deduced. With the application of two small TEVA columns (1.5 mL for each), decontamination factors of >104 for molybdenum and >105 for ruthenium and recovery of 60-95% for technetium were achieved for different environmental samples. An absolute detection...

  20. Identification of novel peptides for horse meat speciation in highly processed foodstuffs.

    Science.gov (United States)

    Claydon, Amy J; Grundy, Helen H; Charlton, Adrian J; Romero, M Rosario

    2015-01-01

    There is a need for robust analytical methods to support enforcement of food labelling legislation. Proteomics is emerging as a complementary methodology to existing tools such as DNA and antibody-based techniques. Here we describe the development of a proteomics strategy for the determination of meat species in highly processed foods. A database of specific peptides for nine relevant animal species was used to enable semi-targeted species determination. This principle was tested for horse meat speciation, and a range of horse-specific peptides were identified as heat stable marker peptides for the detection of low levels of horse meat in mixtures with other species.

  1. Passive Dosing to Determine the Speciation of Hydrophobic Organic Chemicals in Aqueous Samples

    DEFF Research Database (Denmark)

    Birch, Heidi; Gouliarmou, V.; Lützhøft, Hans-Christian Holten

    2010-01-01

    A new analytical approach to determine the speciation of hydrophobic organic analytes is presented. The freely dissolved concentration in a sample is controlled by passive dosing from silicone (poly(dimethylsiloxane)), and the total sample concentration at equilibrium is measured. The free fraction...... is determined as the ratio between measured concentrations in pure water and sample. C-14-labeled fluoranthene served as model analyte, and total sample concentrations were easily measured by liquid scintillation counting. The method was applied to surface water, stormwater runoff, and wastewater...... (SPME). This analytical approach combines simplicity with high precision, and it does not require any phase separation steps....

  2. Bulk-fill resin composites: polymerization contraction, depth of cure, and gap formation.

    Science.gov (United States)

    Benetti, A R; Havndrup-Pedersen, C; Honoré, D; Pedersen, M K; Pallesen, U

    2015-01-01

    The bulk-filling of deep, wide dental cavities is faster and easier than traditional incremental restoration. However, the extent of cure at the bottom of the restoration should be carefully examined in combination with the polymerization contraction and gap formation that occur during the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk-fill materials produced a significantly larger depth of cure and polymerization contraction. Although most of the bulk-fill materials exhibited a gap formation similar to that of the conventional resin composite, two of the low-viscosity bulk-fill resin composites, x-tra base and Venus Bulk Fill, produced larger gaps.

  3. Radiation effects in bulk and nanostructured silicon

    Energy Technology Data Exchange (ETDEWEB)

    Holmstrom, E.

    2012-07-01

    Understanding radiation effects in silicon (Si) is of great technological importance. The material, being the basis of modern semiconductor electronics and photonics, is subjected to radiation already at the processing stage, and in many applications throughout the lifetime of the manufactured component. Despite decades of research, many fundamental questions on the subject are still not satisfactorily answered, and new ones arise constantly as device fabrication shifts towards the nanoscale. In this study, methods of computational physics are harnessed to tackle basic questions on the radiation response of bulk and nanostructured Si systems, as well as to explain atomic-scale phenomena underlying existing experimental results. Empirical potentials and quantum mechanical models are coupled with molecular dynamics simulations to model the response of Si to irradiation and to characterize the created crystal damage. The threshold displacement energy, i.e., the smallest recoil energy required to create a lattice defect, is determined in Si bulk and nanowires, in the latter system also as a function of mechanical strain. It is found that commonly used values for this quantity are drastically underestimated. Strain on the nanowire causes the threshold energy to drop, with an effect on defect production that is significantly higher than in an another nanostructure with similar dimensions, the carbon nanotube. Simulating ion irradiation of Si nanowires reveals that the large surface area to volume ratio of the nanostructure causes up to a three-fold enhancement in defect production as compared to bulk Si. Amorphous defect clusters created by energetic neutron bombardment are predicted, on the basis of their electronic structure and abundance, to cause a deleterious phenomenon called type inversion in Si strip detectors in high-energy physics experiments. The thinning of Si lamellae using a focused ion beam is studied in conjunction with experiment to unravel the cause for

  4. Transformation of bulk alloys to oxide nanowires

    Science.gov (United States)

    Lei, Danni; Benson, Jim; Magasinski, Alexandre; Berdichevsky, Gene; Yushin, Gleb

    2017-01-01

    One dimensional (1D) nanostructures offer prospects for enhancing the electrical, thermal, and mechanical properties of a broad range of functional materials and composites, but their synthesis methods are typically elaborate and expensive. We demonstrate a direct transformation of bulk materials into nanowires under ambient conditions without the use of catalysts or any external stimuli. The nanowires form via minimization of strain energy at the boundary of a chemical reaction front. We show the transformation of multimicrometer-sized particles of aluminum or magnesium alloys into alkoxide nanowires of tunable dimensions, which are converted into oxide nanowires upon heating in air. Fabricated separators based on aluminum oxide nanowires enhanced the safety and rate capabilities of lithium-ion batteries. The reported approach allows ultralow-cost scalable synthesis of 1D materials and membranes.

  5. Combining item and bulk material loss-detection uncertainties

    International Nuclear Information System (INIS)

    Eggers, R.F.

    1982-01-01

    Loss detection requirements, such as five formula kilograms with 99% probability of detection, which apply to the sum of losses from material in both item and bulk form, constitute a special problem for the nuclear material statistician. Requirements of this type are included in the Material Control and Accounting Reform Amendments described in the Advance Notice of Proposed Rule Making (Federal Register, 46(175):45144-46151). Attribute test sampling of items is the method used to detect gross defects in the inventory of items in a given control unit. Attribute sampling plans are designed to detect a loss of a specificed goal quantity of material with a given probability. In contrast to the methods and statistical models used for item loss detection, bulk material loss detection requires all the material entering and leaving a control unit to be measured and the calculation of a loss estimator that will be tested against an appropriate alarm threshold. The alarm threshold is determined from an estimate of the error inherent in the components of the loss estimator. In this paper a simple grahical method of evaluating the combined capabilities of bulk material loss detection methods and item attribute testing procedures will be described. Quantitative results will be given for several cases, indicating how a decrease in the precision of the item loss detection method tends to force an increase in the precision of the bulk loss detection procedure in order to meet the overall detection requirement. 4 figures

  6. Speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Li Xun [Department of Chemistry, Beijing Normal University, Beijing 100875 (China); Department of Chemistry and Life Science, Gannan Teachers College, Ganzhou 341000 (China); Jia Jing [Department of Chemistry, Beijing Normal University, Beijing 100875 (China); Wang Zhenghao [Department of Chemistry, Beijing Normal University, Beijing 100875 (China)]. E-mail: zhwang@bnu.edu.cn

    2006-02-23

    A simple procedure was developed for the speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry (EcHG-AAS), without pre-reduction of As(V). Glassy carbon was selected as cathode material in the flow cell. An optimum catholyte concentration for simultaneous generation of arsine from As(III) and As(V) was 0.06 mol l{sup -1} H{sub 2}SO{sub 4}. Under the optimized conditions, adequate sensitivity and difference in ratio of slopes of the calibration curves for As(III) and As(V) can be achieved at the electrolytic currents of 0.6 and 1 A. The speciation of inorganic arsenic can be performed by controlling the electrolytic currents, and the concentration of As(III) and As(V) in the sample can be calculated according to the equations of absorbance additivity obtained at two selected electrolytic currents. The calibration curves were linear up to 50 ng ml{sup -1} for both As(III) and As(V) at 0.6 and 1 A. The detection limits of the method were 0.2 and 0.5 ng ml{sup -1} for As(III) and As(V) at 0.6 A, respectively. The relative standard deviations were of 2.1% for 20 ng ml{sup -1} As(III) and 2.5% for 20 ng ml{sup -1} As(V). The method was validated by the analysis of human hair certified reference material and successfully applied to speciation of soluble inorganic arsenic in Chinese medicine.

  7. Speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry

    International Nuclear Information System (INIS)

    Li Xun; Jia Jing; Wang Zhenghao

    2006-01-01

    A simple procedure was developed for the speciation of inorganic arsenic by electrochemical hydride generation atomic absorption spectrometry (EcHG-AAS), without pre-reduction of As(V). Glassy carbon was selected as cathode material in the flow cell. An optimum catholyte concentration for simultaneous generation of arsine from As(III) and As(V) was 0.06 mol l -1 H 2 SO 4 . Under the optimized conditions, adequate sensitivity and difference in ratio of slopes of the calibration curves for As(III) and As(V) can be achieved at the electrolytic currents of 0.6 and 1 A. The speciation of inorganic arsenic can be performed by controlling the electrolytic currents, and the concentration of As(III) and As(V) in the sample can be calculated according to the equations of absorbance additivity obtained at two selected electrolytic currents. The calibration curves were linear up to 50 ng ml -1 for both As(III) and As(V) at 0.6 and 1 A. The detection limits of the method were 0.2 and 0.5 ng ml -1 for As(III) and As(V) at 0.6 A, respectively. The relative standard deviations were of 2.1% for 20 ng ml -1 As(III) and 2.5% for 20 ng ml -1 As(V). The method was validated by the analysis of human hair certified reference material and successfully applied to speciation of soluble inorganic arsenic in Chinese medicine

  8. Enhanced bulk heterojunction devices prepared by thermal and solvent vapor annealing processes

    Science.gov (United States)

    Forrest, Stephen R.; Thompson, Mark E.; Wei, Guodan; Wang, Siyi

    2017-09-19

    A method of preparing a bulk heterojunction organic photovoltaic cell through combinations of thermal and solvent vapor annealing are described. Bulk heterojunction films may prepared by known methods such as spin coating, and then exposed to one or more vaporized solvents and thermally annealed in an effort to enhance the crystalline nature of the photoactive materials.

  9. Electrochemical metal speciation in natural and model polyelectrolyte systems

    NARCIS (Netherlands)

    Hoop, van den M.A.G.T.

    1994-01-01

    The purpose of the research described in this thesis was to examine the applicability of electro-analytical techniques in obtaining information on the speciation of metals, i.e. their distribution over different physico-chemical forms, in aquatic systems containing charged macromolecules.

  10. Speciation and determination of priority metals in sediments of Oyun ...

    African Journals Online (AJOL)

    This work was carried out to determine the concentrations, bioavailability and mobility of priority metals in sediments of Oyun River, Sango, Ilorin, Nigeria. The river sediments were sampled at six selected locations and the samples were analyzed for some certain priority metals to determine the concentration, speciation and ...

  11. Speciation and phase separation of water in quartz (A review ...

    African Journals Online (AJOL)

    By sp3-hybridization of electron bonds, the water molecule exhibits a tetrahedral charged structure, leading to various water point defects in the form of substitution of ... The formation of combined defect [SiO4]-H2O-M+ [M3+O4] upon water speciation (M+ is metallic ion), is an indication of the presence of hydrous species.

  12. Heavy metal speciation and their accumulation in sediments of Lake ...

    African Journals Online (AJOL)

    UFUOMA

    Key words: Heavy metals, chemical speciation, sediments, Burullus, Lake. INTRODUCTION ..... fuel for use in internal combustion engines and in making batteries. ..... (Tuner, 1989). According to this model, human risk assessment was .... 593 - 594. Hökanson L (1980). "Ecological Risk Index for Aquatic Pollution. Control.

  13. Comparative Studies of the Speciation Patterns of Nickel and ...

    African Journals Online (AJOL)

    Results of speciation stdies of nickel and chromium in wastewater, surface and groundwater systems using flame atomic absorption spectrometry (FAAS), graphite furnace atomic absorption spectrometry (GFAAS) and differential pulse adsorptive cathodic stripping voltammetry (DPAdCSV) are presented. Dimethylglyoxime ...

  14. Behavioural isolation may facilitate homoploid hybrid speciation in cichlid fish

    NARCIS (Netherlands)

    Selz, O. M.; Thommen, R.; Maan, M. E.; Seehausen, O.

    Hybrid speciation is constrained by the homogenizing effects of gene flow from the parental species. In the absence of post-mating isolation due to structural changes in the genome, or temporal or spatial premating isolation, another form of reproductive isolation would be needed for homoploid

  15. The molecular basis of speciation: from patterns to processes, rules ...

    Indian Academy of Sciences (India)

    male; large X-effect; meiotic drive; genomic conflict. Abstract. The empirical study of speciation has brought us closer to unlocking the origins of life's vast diversity. By examining recently formed species, a number of general patterns, or rules, ...

  16. Mitochondrial Recombination and Introgression during Speciation by Hybridization.

    Science.gov (United States)

    Leducq, Jean-Baptiste; Henault, Mathieu; Charron, Guillaume; Nielly-Thibault, Lou; Terrat, Yves; Fiumera, Heather L; Shapiro, B Jesse; Landry, Christian R

    2017-08-01

    Genome recombination is a major source of genotypic diversity and contributes to adaptation and speciation following interspecies hybridization. The contribution of recombination in these processes has been thought to be largely limited to the nuclear genome because organelles are mostly uniparentally inherited in animals and plants, which prevents recombination. Unicellular eukaryotes such as budding yeasts do, however, transmit mitochondria biparentally, suggesting that during hybridization, both parents could provide alleles that contribute to mitochondrial functions such as respiration and metabolism in hybrid populations or hybrid species. We examined the dynamics of mitochondrial genome transmission and evolution during speciation by hybridization in the natural budding yeast Saccharomyces paradoxus. Using population-scale mitochondrial genome sequencing in two endemic North American incipient species SpB and SpC and their hybrid species SpC*, we found that both parental species contributed to the hybrid mitochondrial genome through recombination. We support our findings by showing that mitochondrial recombination between parental types is frequent in experimental crosses that recreate the early step of this speciation event. In these artificial hybrids, we observed that mitochondrial genome recombination enhances phenotypic variation among diploid hybrids, suggesting that it could play a role in the phenotypic differentiation of hybrid species. Like the nuclear genome, the mitochondrial genome can, therefore, also play a role in hybrid speciation. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Heavy metal speciation and their accumulation in sediments of Lake ...

    African Journals Online (AJOL)

    Several sediment samples in Lake Burullus have been affected by the discharges of heavy metals through different drains. The study aimed to analyze the chemical speciation of these metals. In particular, the chemical forms of Cd, Cu, Fe, Mn, Pb and Zn in sediments collected in spring season were studied using a ...

  18. Mercury speciation with fluorescent gold nanocluster as a probe.

    Science.gov (United States)

    Yang, Jian-Yu; Yang, Ting; Wang, Xiao-Yan; Chen, Ming-Li; Yu, Yong-Liang; Wang, Jian-Hua

    2018-05-11

    Fluorescent nanoparticles are widely used for sensing biologically significant species. However, it is rarely reported for the discrimination or speciation of metal species. In this work, we report for the first time the speciation of mercury (Hg 2+ ) and methylmercury (CH 3 Hg + ) by taking advantage of the fluorescence feature of folic acid-capped gold nanoclusters (FA-AuNCs). FA-Au NCs exhibit an average size of 2.08±0.15 nm and a maximum emission at λ ex /λ em = 280/440 nm with a quantum yield of 27.3%. It is interesting that Hg 2+ causes a significant quench on the fluorescence of FA-Au NCs, whereas CH 3 Hg + leads to a remarkable fluorescence enhancement. Based on this discriminative fluorescent response between Hg 2+ and CH 3 Hg + , a novel nanosensor for the speciation of CH 3 Hg + and Hg 2+ was developed, providing limits of detection (LOD) of 28 nM for Hg 2+ and 25 nM for CH 3 Hg + within 100-1000 nM. This sensing system is highly selective to mercury. Its practical applications were further demonstrated by the analysis of CH 3 Hg + and the speciation of mercury (CH 3 Hg + and Hg 2+ ) in environmental water and fish samples.

  19. Geometry, charge distribution, and surface speciation of phosphate on goethite.

    NARCIS (Netherlands)

    Rahnemaie, R.; Hiemstra, T.; Riemsdijk, van W.H.

    2007-01-01

    The surface speciation of phosphate has been evaluated with surface complexation modeling using an interfacial charge distribution (CD) approach based on ion adsorption and ordering of interfacial water. In the CD model, the charge of adsorbed ions is distributed over two electrostatic potentials in

  20. Speciation of Fe in Fe-modified zeolite catalysts

    Czech Academy of Sciences Publication Activity Database

    Smoláková, L.; Grygar, Tomáš; Čapek, L.; Schneeweiss, Oldřich; Zbořil, R.

    2010-01-01

    Roč. 647, č. 1 (2010), s. 8-19 ISSN 1572-6657 Institutional research plan: CEZ:AV0Z40320502; CEZ:AV0Z20410507 Keywords : solid state speciation * Fe2O3 * heterogeneous catalysts Subject RIV: CB - Analytical Chemistry, Separation Impact factor: 2.732, year: 2010

  1. Speciation Studies of Some Toxic Metal Complexes of Glycylglycine ...

    African Journals Online (AJOL)

    NICO

    mixtures apart from its established utility in understanding ... Chemical speciation of metals is important for an understand- ... Titrations with differ- ent ratios (1:2.5, 1:3.5 and 1:5) of metal-ligand were performed with 0.4 mol L–1 sodium hydroxide solution. The mixtures obtained from PG and water are non-ideal due.

  2. Speciation of Candida isolates obtained from diarrheal stool

    Directory of Open Access Journals (Sweden)

    Beena Uppal

    2016-01-01

    Conclusion Candida diarrhea was mostly seen in individuals younger than 12 years, most commonly caused by C. krusei. Resistance to fluconazole was high. A rising resistance to amphotericin B is alarming. Speciation of Candida is important to see the difference in antifungal susceptibility in different species.

  3. FINE PARTICULATE MATTER (PM) AND ORGANIC SPECIATION OF FIREPLACE EMISSIONS

    Science.gov (United States)

    This paper presents a summary of fireplace particle size and organic speciation data gathered to date in an on-going project. Tests are being conducted in a residential wood combustion (RWC) laboratory on three factory-built fireplaces. RWC wood smoke particles <10?m (PM10) con...

  4. Speciation and bioavailability of copper in Lake Tjeukemeer

    NARCIS (Netherlands)

    Verweij, W.

    1991-01-01

    Chapter 1: introduction

    In this thesis an account is given of a research project dealing with the chemical speciation and bioavailability of copper in Lake Tjeukemeer, a lake in the north of the Netherlands. The reason for the initiation of this project was a lack of

  5. Distribution and Speciation of Mercury in Mine Waste Dumps

    Czech Academy of Sciences Publication Activity Database

    Hojdová, Maria; Navrátil, Tomáš; Rohovec, Jan

    2008-01-01

    Roč. 80, č. 3 (2008), s. 237-241 ISSN 0007-4861 R&D Projects: GA AV ČR(CZ) KJB300130615 Institutional research plan: CEZ:AV0Z30130516 Keywords : mercury * mine waste * mercury speciation * thermo-desorption analysis Subject RIV: DD - Geochemistry Impact factor: 0.609, year: 2008

  6. Phytotoxicity and bioavailablity of nickel: chemical speciation and bioaccumulation

    NARCIS (Netherlands)

    Weng, L.P.; Lexmond, T.M.; Wolthoorn, A.; Temminghoff, E.J.M.; Riemsdijk, van W.H.

    2003-01-01

    The effect of pH on the bioaccumulation of nickel (Ni) by plants is opposite when using a nutrient solution or a soil as a growing medium. This paradox can be understood if the pH effect on the bioaccumulation, on the chemical speciation in the soil solution, and on the binding to the soil of Ni are

  7. Coupling brane fields to bulk supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Parameswaran, Susha L. [Uppsala Univ. (Sweden). Theoretical Physics; Schmidt, Jonas [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2010-12-15

    In this note we present a simple, general prescription for coupling brane localized fields to bulk supergravity. We illustrate the procedure by considering 6D N=2 bulk supergravity on a 2D orbifold, with brane fields localized at the fixed points. The resulting action enjoys the full 6D N=2 symmetries in the bulk, and those of 4D N=1 supergravity at the brane positions. (orig.)

  8. Interrelated temperature dependence of bulk etch rate and track length saturation time in CR-39 detector

    International Nuclear Information System (INIS)

    Azooz, A.A.; Al-Jubbori, M.A.

    2013-01-01

    Highlights: • New empirical parameterization of CR-39 bulk etch rate. • Bulk etch rates measurements using two different methods give consistent results. • Temperature independence of track saturation length. • Two empirical relation between bulk etch rate and temperature are suggested. • Simple inverse relation between bulk etch rate and track saturation time. -- Abstract: Experimental measurements of the etching solution temperature dependence of bulk etch rate using two independent methods revealed a few interesting properties. It is found that while the track saturation length is independent of etching temperature, the etching time needed to reach saturation is strongly temperature-dependent. It is demonstrated that there is systematic simple inverse relation between track saturation time, and etching solution temperature. In addition, and although, the relation between the bulk etch rate and etching solution temperature can be reasonably described by a modified form of the Arrhenius equation, better fits can be obtained by another equation suggested in this work

  9. Longitudinal and bulk viscosities of expanded rubidium

    International Nuclear Information System (INIS)

    Zaheri, Ali Hossein Mohammad; Srivastava, Sunita; Tankeshwar, K

    2003-01-01

    First three non-vanishing sum rules for the bulk and longitudinal stress auto-correlation functions have been evaluated for liquid Rb at six thermodynamic states along the liquid-vapour coexistence curve. The Mori memory function formalism and the frequency sum rules have been used to calculate bulk and longitudinal viscosities. The results thus obtained for the ratio of bulk viscosity to shear viscosity have been compared with experimental and other theoretical predictions wherever available. The values of the bulk viscosity have been found to be more than the corresponding values of the shear viscosity for all six thermodynamic states investigated here

  10. Speciation analysis of cobalt in foods by high-performance liquid chromatography and neutron activation analysis

    International Nuclear Information System (INIS)

    Muto, Toshio; Koyama, Motoko

    1994-01-01

    A combined method by coupling high-performance liquid chromatography (HPLC, as a separation method) with neutron activation analysis (as a detection method) have been applied to the speciation analysis of cobalt in daily foods (e.g. egg, fish and milk). Cobalt species including free cobalt, vitamin B 12 and protein-bound cobalt were separated with a preparative HPLC and a centrifuge. Subsequently, the determination of cobalt in the separated species was made by neutron activation analysis. The results showed that the content of the total cobalt in the foods was found to lie in the range 0.4-11ng/g(0.4-11ppb) based on wet weight. The compositions of free cobalt, vitamin B 12 and protein-bound cobalt were ranged 16-43%, 55-73%, 2.3-17%, respectively. These experimental evidences suggest that the combination of HPLC and neutron activation analysis is expected to be a useful tool for speciation analysis of trace elements in biological as well as environmental materials. (author)

  11. Detection and speciation of transuranium elements in synthetic groundwater via pulsed-laser excitation

    International Nuclear Information System (INIS)

    Beitz, J.V.; Bowers, D.L.; Doxtader, M.M.; Maroni, V.A.; Reed, D.T.

    1987-01-01

    High sensitivity methods for detection and speciation of complexed transuranium ions in synthetic basalt groundwater, and simplified analogs, are being developed which exploit advances in pulsed laser technology. The first demonstration of high sensitivity detection of a transuranium ion at temperatures significantly above ambient is reported using laser photoacoustic spectroscopy (LPAS). The existence of enhanced LPAS signal amplitudes with increasing temperature in aqueous solution is confirmed in LPAS spectra recorded at 30 C, 60 C and 90 C using micromolar concentrations of /sup 241/Am/sup 3+/. A detection sensitivity of 8.5 parts per trillion (weight basis) of /sup 244/Cm/sup 3+/ in a simplified basalt groundwater at 22 C has been achieved using laser-induced fluorescence spectroscopy (LIF). This corresponds to 1 x 10/sup 8/ Cm/sup 3+/ ions in the laser beam. The detailed spectroscopic information obtained by this method points to the existence of previously unobserved Cm/sup 3+/ species. A brief assessment of the applicability and sensitivity of LPAS and LIF methods for speciating transuranium ions in near-neutral pH aqueous solution, such as the groundwater expected in a basalt nuclear waste repository, is presented. 27 refs., 3 figs

  12. Bulk sample self-attenuation correction by transmission measurement

    International Nuclear Information System (INIS)

    Parker, J.L.; Reilly, T.D.

    1976-01-01

    Various methods used in either finding or avoiding the attenuation correction in the passive γ-ray assay of bulk samples are reviewed. Detailed consideration is given to the transmission method, which involves experimental determination of the sample linear attenuation coefficient by measuring the transmission through the sample of a beam of gamma rays from an external source. The method was applied to box- and cylindrically-shaped samples

  13. Large-scale Homogenization of Bulk Materials in Mammoth Silos

    NARCIS (Netherlands)

    Schott, D.L.

    2004-01-01

    This doctoral thesis concerns the large-scale homogenization of bulk materials in mammoth silos. The objective of this research was to determine the best stacking and reclaiming method for homogenization in mammoth silos. For this purpose a simulation program was developed to estimate the

  14. Aspects of silicon bulk lifetimes

    Science.gov (United States)

    Landsberg, P. T.

    1985-01-01

    The best lifetimes attained for bulk crytalline silicon as a function of doping concentrations are analyzed. It is assumed that the dopants which set the Fermi level do not contribute to the recombination traffic which is due to the unknown defect. This defect is assumed to have two charge states: neutral and negative, the neutral defect concentration is frozen-in at some temperature T sub f. The higher doping concentrations should include the band-band Auger effect by using a generalization of the Shockley-Read-Hall (SRH) mechanism. The generalization of the SRH mechanism is discussed. This formulation gives a straightforward procedure for incorporating both band-band and band-trap Auger effects in the SRH procedure. Two related questions arise in this context: (1) it may sometimes be useful to write the steady-state occupation probability of the traps implied by SRH procedure in a form which approximates to the Fermi-Dirac distribution; and (2) the effect on the SRH mechanism of spreading N sub t levels at one energy uniformly over a range of energies is discussed.

  15. Mass production of bulk artificial nacre with excellent mechanical properties.

    Science.gov (United States)

    Gao, Huai-Ling; Chen, Si-Ming; Mao, Li-Bo; Song, Zhao-Qiang; Yao, Hong-Bin; Cölfen, Helmut; Luo, Xi-Sheng; Zhang, Fu; Pan, Zhao; Meng, Yu-Feng; Ni, Yong; Yu, Shu-Hong

    2017-08-18

    Various methods have been exploited to replicate nacre features into artificial structural materials with impressive structural and mechanical similarity. However, it is still very challenging to produce nacre-mimetics in three-dimensional bulk form, especially for further scale-up. Herein, we demonstrate that large-sized, three-dimensional bulk artificial nacre with comprehensive mimicry of the hierarchical structures and the toughening mechanisms of natural nacre can be facilely fabricated via a bottom-up assembly process based on laminating pre-fabricated two-dimensional nacre-mimetic films. By optimizing the hierarchical architecture from molecular level to macroscopic level, the mechanical performance of the artificial nacre is superior to that of natural nacre and many engineering materials. This bottom-up strategy has no size restriction or fundamental barrier for further scale-up, and can be easily extended to other material systems, opening an avenue for mass production of high-performance bulk nacre-mimetic structural materials in an efficient and cost-effective way for practical applications.Artificial materials that replicate the mechanical properties of nacre represent important structural materials, but are difficult to produce in bulk. Here, the authors exploit the bottom-up assembly of 2D nacre-mimetic films to fabricate 3D bulk artificial nacre with an optimized architecture and excellent mechanical properties.

  16. Running with rugby balls: bulk renormalization of codimension-2 branes

    Science.gov (United States)

    Williams, M.; Burgess, C. P.; van Nierop, L.; Salvio, A.

    2013-01-01

    We compute how one-loop bulk effects renormalize both bulk and brane effective interactions for geometries sourced by codimension-two branes. We do so by explicitly integrating out spin-zero, -half and -one particles in 6-dimensional Einstein-Maxwell-Scalar theories compactified to 4 dimensions on a flux-stabilized 2D geometry. (Our methods apply equally well for D dimensions compactified to D - 2 dimensions, although our explicit formulae do not capture all divergences when D > 6.) The renormalization of bulk interactions are independent of the boundary conditions assumed at the brane locations, and reproduce standard heat-kernel calculations. Boundary conditions at any particular brane do affect how bulk loops renormalize this brane's effective action, but not the renormalization of other distant branes. Although we explicitly compute our loops using a rugby ball geometry, because we follow only UV effects our results apply more generally to any geometry containing codimension-two sources with conical singularities. Our results have a variety of uses, including calculating the UV sensitivity of one-loop vacuum energy seen by observers localized on the brane. We show how these one-loop effects combine in a surprising way with bulk back-reaction to give the complete low-energy effective cosmological constant, and comment on the relevance of this calculation to proposed applications of codimension-two 6D models to solutions of the hierarchy and cosmological constant problems.

  17. Applicability of multisyringe chromatography coupled to cold-vapor atomic fluorescence spectrometry for mercury speciation analysis

    International Nuclear Information System (INIS)

    Guzmán-Mar, J.L.; Hinojosa-Reyes, L.; Serra, A.M.; Hernández-Ramírez, A.; Cerdà, V.

    2011-01-01

    Graphical abstract: An automatic system, based on the applicability of multisyringe chromatography (MSC) coupled to cold-vapor atomic fluorescence spectrometry (CV/AFS) detection is developed for mercury speciation. Highlights: ► The on-line coupling of MSC to CV/AFS was developed for mercury speciation analysis. ► The speciation of MeHg + , Hg 2+ and EtHg + was achieved on a RP C18 monolithic column. ► The hyphenated system provided higher sample throughput compared to HPLC–CV/AFS. ► The limits of detection for mercury species were comparable or better than those reported by HPLC–CV/AFS. ► The developed method also provided low instrumental and operational costs. - Abstract: In this paper, a novel automatic approach for the speciation of inorganic mercury (Hg 2+ ), methylmercury (MeHg + ) and ethylmercury (EtHg + ) using multisyringe chromatography (MSC) coupled to cold-vapor atomic fluorescence spectrometry (CV/AFS) was developed. For the first time, the separation of mercury species was accomplished on a RP C18 monolithic column using a multi-isocratic elution program. The elution protocol involved the use of 0.005% 2-mercapthoethanol in 240 mM ammonium acetate (pH 6)–acetonitrile (99:1, v/v), followed by 0.005% 2-mercapthoethanol in 240 mM ammonium acetate (pH 6)–acetonitrile (90:10, v/v). The eluted mercury species were then oxidized under post-column UV radiation and reduced using tin(II) chloride in an acidic medium. Subsequently, the generated mercury metal were separated from the reaction mixture and further atomized in the flame atomizer and detected by AFS. Under the optimized experimental conditions, the limits of detection (3σ) were found to be 0.03, 0.11 and 0.09 μg L −1 for MeHg + , Hg 2+ and EtHg + , respectively. The relative standard deviation (RSD, n = 6) of the peak height for 3, 6 and 3 μg L −1 of MeHg + , Hg 2+ and EtHg + (as Hg) ranged from 2.4 to 4.0%. Compared with the conventional HPLC–CV/AFS hyphenated systems

  18. Speciation of trace elements in the environmental studies

    International Nuclear Information System (INIS)

    Reddy, A.V.R.

    2012-01-01

    Elements present at trace levels, often referred as trace elements, play an important role in the environment and in the functioning of life on our planet. Trace elements in environment present as free metal ions or incorporated into colloids or attached to particulate matter or exist in different physical and chemical forms. It is well established that some elements are highly toxic and some are essential, but can become toxic at higher doses. It is also now known that the forms of elements (speciation) and their amounts are more important than the chemical dose of the elements as their interaction depends on different species. For example, Cr(VI) ions are considered far more toxic than Cr(III), whereas As(III) is more toxic than As(V). Similarly, in the case of mercury, both methylmercury and inorganic mercury are toxic but they show different levels of toxicity. Thus the adverse effects depend on the nature of species of the elements and therefore speciation studies are of paramount importance in many areas like toxicology, environmental chemistry and geochemisty. In view of this, speciation studies is a challenge to analytical chemists as the measurement methodologies have to be carefully developed, validated and applied. The grand challenge is to obtain quality data ensuring traceability, as the data obtained will be used in modeling for predicting the environmental impacts. In this talk importance of speciation and challenges to environmental analytical chemists will be discussed along with the following three speciation studies on Cr, U and Hg which were carried out in our laboratories

  19. Sex chromosomes and speciation in birds and other ZW systems.

    Science.gov (United States)

    Irwin, Darren E

    2018-02-14

    Theory and empirical patterns suggest a disproportionate role for sex chromosomes in evolution and speciation. Focusing on ZW sex determination (females ZW, males ZZ; the system in birds, many snakes, and lepidopterans), I review how evolutionary dynamics are expected to differ between the Z, W and the autosomes, discuss how these differences may lead to a greater role of the sex chromosomes in speciation and use data from birds to compare relative evolutionary rates of sex chromosomes and autosomes. Neutral mutations, partially or completely recessive beneficial mutations, and deleterious mutations under many conditions are expected to accumulate faster on the Z than on autosomes. Sexually antagonistic polymorphisms are expected to arise on the Z, raising the possibility of the spread of preference alleles. The faster accumulation of many types of mutations and the potential for complex evolutionary dynamics of sexually antagonistic traits and preferences contribute to a role for the Z chromosome in speciation. A quantitative comparison among a wide variety of bird species shows that the Z tends to have less within-population diversity and greater between-species differentiation than the autosomes, likely due to both adaptive evolution and a greater rate of fixation of deleterious alleles. The W chromosome also shows strong potential to be involved in speciation, in part because of its co-inheritance with the mitochondrial genome. While theory and empirical evidence suggest a disproportionate role for sex chromosomes in speciation, the importance of sex chromosomes is moderated by their small size compared to the whole genome. © 2018 John Wiley & Sons Ltd.

  20. Evaluation of mercury speciation and removal through air pollution control devices of a 190 MW boiler.

    Science.gov (United States)

    Wu, Chengli; Cao, Yan; Dong, Zhongbing; Cheng, Chinmin; Li, Hanxu; Pan, Weiping

    2010-01-01

    Air pollution control devices (APCDs) are installed at coal-fired power plants for air pollutant regulation. Selective catalytic reduction (SCR) and wet flue gas desulfurization (FGD) systems have the co-benefits of air pollutant and mercury removal. Configuration and operational conditions of APCDs and mercury speciation affect mercury removal efficiently at coal-fired utilities. The Ontario Hydro Method (OHM) recommended by the U.S. Environmental Protection Agency (EPA) was used to determine mercury speciation simultaneously at five sampling locations through SCR-ESP-FGD at a 190 MW unit. Chlorine in coal had been suggested as a factor affecting the mercury speciation in flue gas; and low-chlorine coal was purported to produce less oxidized mercury (Hg2+) and more elemental mercury (Hg0) at the SCR inlet compared to higher chlorine coal. SCR could oxidize elemental mercury into oxidized mercury when SCR was in service, and oxidation efficiency reached 71.0%. Therefore, oxidized mercury removal efficiency was enhanced through a wet FGD system. In the non-ozone season, about 89.5%-96.8% of oxidized mercury was controlled, but only 54.9%-68.8% of the total mercury was captured through wet FGD. Oxidized mercury removal efficiency was 95.9%-98.0%, and there was a big difference in the total mercury removal efficiencies from 78.0% to 90.2% in the ozone season. Mercury mass balance was evaluated to validate reliability of OHM testing data, and the ratio of mercury input in the coal to mercury output at the stack was from 0.84 to 1.08.