10 CFR Appendix N to Part 110 - Illustrative List of Lithium Isotope Separation Facilities, Plants and Equipment Under NRC's...

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 2 2013-01-01 2013-01-01 false Illustrative List of Lithium Isotope Separation Facilities... Appendix N to Part 110—Illustrative List of Lithium Isotope Separation Facilities, Plants and Equipment Under NRC's Export Licensing Authority a. Facilities or plants for the separation of lithium isotopes. b...

10 CFR Appendix N to Part 110 - Illustrative List of Lithium Isotope Separation Facilities, Plants and Equipment Under NRC's...

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 2 2011-01-01 2011-01-01 false Illustrative List of Lithium Isotope Separation Facilities... Appendix N to Part 110—Illustrative List of Lithium Isotope Separation Facilities, Plants and Equipment Under NRC's Export Licensing Authority a. Facilities or plants for the separation of lithium isotopes. b...

10 CFR Appendix N to Part 110 - Illustrative List of Lithium Isotope Separation Facilities, Plants and Equipment Under NRC's...

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 2 2010-01-01 2010-01-01 false Illustrative List of Lithium Isotope Separation Facilities... Appendix N to Part 110—Illustrative List of Lithium Isotope Separation Facilities, Plants and Equipment Under NRC's Export Licensing Authority a. Facilities or plants for the separation of lithium isotopes. b...

Student-Related Variables as Predictors of Academic Achievement among Some Undergraduate Psychology Students in Barbados

ERIC Educational Resources Information Center

Fayombo, Grace Adebisi

2011-01-01

This study examined some student-related variables (interest in higher education, psychological resilience and study habit) as predictors of academic achievement among 131 (M (mean) = 28.17, SD (standard deviation) = 1.61) first year psychology students in the Introduction to Developmental Psychology class in UWI (The University of the West…

Conformational effect of dicyclo-hexano-18-crown-6 on isotopic fractionation of zinc: DFT approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boda, A.; Singha Deb, A. K.; Ali, Sk. M.

2014-04-24

Generalized gradient approximated BP86 density functional employing triple zeta valence plus polarization (TZVP) basis set has been used to compute the reduced partition function ratio and isotopic separation factor for zinc isotopes. The isotopic separation factor was found to be in good agreement with the experimental results. The isotopic separation factor was found to depend on the conformation of the crown ether ligand. The trans-trans conformation shows the highest fractionation compared to cis-cis conformer. The present theoretical results can thus be used to plan the isotope separation experiments.

Mathematical Model of Nonstationary Separation Processes Proceeding in the Cascade of Gas Centrifuges in the Process of Separation of Multicomponent Isotope Mixtures

NASA Astrophysics Data System (ADS)

Orlov, A. A.; Ushakov, A. A.; Sovach, V. P.

2017-03-01

We have developed and realized on software a mathematical model of the nonstationary separation processes proceeding in the cascades of gas centrifuges in the process of separation of multicomponent isotope mixtures. With the use of this model the parameters of the separation process of germanium isotopes have been calculated. It has been shown that the model adequately describes the nonstationary processes in the cascade and is suitable for calculating their parameters in the process of separation of multicomponent isotope mixtures.

Laser isotope separation of erbium and other isotopes

DOEpatents

Haynam, Christopher A.; Worden, Earl F.

1995-01-01

Laser isotope separation is accomplished using at least two photoionization pathways of an isotope simultaneously, where each pathway comprises two or more transition steps. This separation method has been applied to the selective photoionization of erbium isotopes, particularly for the enrichment of .sup.167 Er. The hyperfine structure of .sup.167 Er was used to find two three-step photoionization pathways having a common upper energy level.

Separation of Isotopes by Electromigration in Fused Salts; SEPARATION DES ISOTOPES PAR ELECTROMIGRATION EN SELS FONDUS (in French)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menes, F.

1961-12-01

A process is given for the separation of isotopes by reflux electromigration of fused salts. The process is carried out in a countercurrent manner on a fused mixture of a salt containing the isotopic cations with a salt having the same anion and a cation with a mobility as near as possible to that of the isotopic cations. An electrolytic cell for carrying out the process is described. Examples are presented of the process in which lithium-6 and lithium-7 are separated in a LiBr-KBr mixture, and calcium isotopes are separated in CaBr/sub 2/-KBr and CaBr/sub 2/- LiBr systems. (N.W.R.)

Method of isotope separation by chemi-ionization

DOEpatents

Wexler, Sol; Young, Charles E.

1977-05-17

A method for separating specific isotopes present in an isotopic mixture by aerodynamically accelerating a gaseous compound to form a jet of molecules, and passing the jet through a stream of electron donor atoms whereby an electron transfer takes place, thus forming negative ions of the molecules. The molecular ions are then passed through a radiofrequency quadrupole mass filter to separate the specific isotopes. This method may be used for any compounds having a sufficiently high electron affinity to permit negative ion formation, and is especially useful for the separation of plutonium and uranium isotopes.

Laser isotope separation of erbium and other isotopes

DOEpatents

Haynam, C.A.; Worden, E.F.

1995-08-22

Laser isotope separation is accomplished using at least two photoionization pathways of an isotope simultaneously, where each pathway comprises two or more transition steps. This separation method has been applied to the selective photoionization of erbium isotopes, particularly for the enrichment of {sup 167}Er. The hyperfine structure of {sup 167}Er was used to find two three-step photoionization pathways having a common upper energy level. 3 figs.

Integration of Blackboard in the Online Learning Environment

ERIC Educational Resources Information Center

Masino, Monica

2015-01-01

Over the past 5 years there seems to have been an influx of university's across the nation moving their academic programs to the blended environment. While the purpose of distance education is to make education and training more available to persons that may not have time to attend a face-to-face course or training. In 2008, the UWI created the…

The Nexus between Stakeholder Engagement and Instructional Quality: The Case of the UWI Open Campus's Awareness and Professional Development towards a Quality Support Framework

ERIC Educational Resources Information Center

Gilzene-Cheese, Florence

2015-01-01

With changes in the global economic landscape, universities are employing adjunct staff to instruct their online courses in new and expanding programs. Concomitantly, the growth of information and communication technology worldwide has facilitated the creation of classrooms without walls and universities without borders. The challenge for…

Method for discriminative particle selection

DOEpatents

Post, Richard F.

1992-01-01

The invention is a method and means for separating ions or providing an ion beam. The invention generates ions of the isotopes to be separated, and then provides a traveling electric potential hill created by a sequential series of quasi static electric potential hills. By regulating the velocity and potential amplitude of the traveling electric potential hill ionized isotopes are selectively positively or negatively accelerated. Since the ionized isotopes have differing final velocities, the isotopes may be collected separately or used to produce an ion beam of a selected isotope.

Method and apparatus for separation of heavy and tritiated water

DOEpatents

Lee, Myung W.

2001-01-01

The present invention is a bi-thermal membrane process for separating and recovering hydrogen isotopes from a fluid containing hydrogen isotopes, such as water and hydrogen gas. The process in accordance with the present invention provides counter-current cold and hot streams of the fluid separated with a thermally insulating and chemically transparent proton exchange membrane (PEM). The two streams exchange hydrogen isotopes through the membrane: the heavier isotopes migrate into the cold stream, while the lighter isotopes migrate into the hot stream. The heavy and light isotopes are continuously withdrawn from the cold and hot streams respectively.

Increasing Public Access to University Qualifications: Evolution of The University of the West Indies Open Campus

ERIC Educational Resources Information Center

Thomas, Michael L.; Soares, Judith

2009-01-01

This paper traces the evolution of The University of the West Indies' Open Campus (UWIOC), which is expected to expand service and increase access to the underserved communities of the Eastern Caribbean. At present, UWI, which caters to the needs of the 16 far flung countries of the Commonwealth Caribbean, has not been able to fully serve these…

Our Hidden Past: Peacetime

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Ray

Y-12 separated isotopes to win the war, then during the 1950s separated isotopes to save lives. Y-12's calutrons were used for a peacetime mission in the stable isotope program. Y-12 provided stable isotopes for research in medicine, agriculture, industry and biology.

Our Hidden Past: Peacetime

ScienceCinema

Smith, Ray

2018-06-04

Y-12 separated isotopes to win the war, then during the 1950s separated isotopes to save lives. Y-12's calutrons were used for a peacetime mission in the stable isotope program. Y-12 provided stable isotopes for research in medicine, agriculture, industry and biology.

Preparative separation of underivatized amino acids for compound-specific stable isotope analysis and radiocarbon dating of hydrolyzed bone collagen.

PubMed

Tripp, Jennifer A; McCullagh, James S O; Hedges, Robert E M

2006-01-01

Analysis of stable and radioactive isotopes from bone collagen provides useful information to archaeologists about the origin and age of bone artifacts. Isolation and analysis of single amino acids from the proteins can provide additional and more accurate information by removing contamination and separating a bulk isotope signal into its constituent parts. In this paper, we report a new method for the separation and isolation of underivatized amino acids from bone collagen, and their analysis by isotope ratio MS and accelerator MS. RP chromatography is used to separate the amino acids with nonpolar side chains, followed by an ion pair separation to isolate the remaining amino acids. The method produces single amino acids with little or no contamination from the separation process and allows for the measurement of accurate stable isotope ratios and pure samples for radiocarbon dating.

Laser-induced separation of hydrogen isotopes in the liquid phase

DOEpatents

Freund, Samuel M.; Maier, II, William B.; Beattie, Willard H.; Holland, Redus F.

1980-01-01

Hydrogen isotope separation is achieved by either (a) dissolving a hydrogen-bearing feedstock compound in a liquid solvent, or (b) liquefying a hydrogen-bearing feedstock compound, the liquid phase thus resulting being kept at a temperature at which spectral features of the feedstock relating to a particular hydrogen isotope are resolved, i.e., a clear-cut isotope shift is delineated, irradiating the liquid phase with monochromatic radiation of a wavelength which at least preferentially excites those molecules of the feedstock containing a first hydrogen isotope, inducing photochemical reaction in the excited molecules, and separating the reaction product containing the first isotope from the liquid phase.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hitchcock, D.; Colon-Mercado, H.; Krentz, T.

Hydrogen isotope separation is critical to the DOE’s mission in environmental remediation and nuclear nonproliferation. Isotope separation is also a critical technology for the NNSA, and the ability to perform the separations at room temperature with a relatively small amount of power and space would be a major advancement for their respective missions. Recent work has shown that 2-D materials such as graphene and hexagonal boron nitride can act as an isotopic sieve at room temperature; efficiently separating hydrogen isotopes in water with reported separation ratios of 10:1 for hydrogen: deuterium separation for a single pass. The work performed heremore » suggests that this technique has merit, and furthermore, we are investigating optimization and scale up of the required 2-D material based membranes.« less

Urban-wildland fires: how California and other regions of the US can learn from Australia

NASA Astrophysics Data System (ADS)

Stephens, Scott L; Adams, Mark A; Handmer, John; Kearns, Faith R; Leicester, Bob; Leonard, Justin; Moritz, Max A

2009-01-01

Most urban-wildland interface (UWI) fires in California and the other regions of the US are managed in a similar fashion: fire agencies anticipate the spread of fire, mandatory evacuations are ordered, and professional fire services move in and attempt to suppress the fires. This approach has not reduced building losses in California. Conversely, losses and the associated suite of environmental impacts, including reduced air quality, have dramatically increased over the last three decades. In contrast to California, Australia has developed a more effective 'Prepare, stay and defend, or leave early' policy. Using this approach, trained residents decide whether they will stay and actively defend their well-prepared property or leave early before a fire threatens them. Australian strategies have the distinct advantage of engaging and preparing those most affected by such fires: homeowners. Investing more in fire suppression alone, the common response after large UWI fires in California, will not reduce losses. US society has attempted to accommodate many of the natural hazards inherent to the landscapes that we inhabit; by examining the Australian model, we may approach a more sustainable coexistence with fire as well. However, it should be noted that some California communities are so vulnerable that a 'Prepare and leave early' strategy may be the only option.

Photochemical isotope separation

DOEpatents

Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

1987-01-01

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Laser isotope separation

DOEpatents

Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Boyer, Keith; Greiner, Norman R.

1988-01-01

A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

Isotope separation by laser means

DOEpatents

Robinson, C. Paul; Jensen, Reed J.; Cotter, Theodore P.; Greiner, Norman R.; Boyer, Keith

1982-06-15

A process for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium.

Isotope separation by photoselective dissociative electron capture

DOEpatents

Stevens, C.G.

1978-08-29

Disclosed is a method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, [sup 235]UF[sub 6] is separated from a UF[sub 6] mixture by selective excitation followed by dissociative electron capture into [sup 235]UF[sub 5]- and F. 2 figs.

Isotope separation by photoselective dissociative electron capture

DOEpatents

Stevens, Charles G. [Pleasanton, CA

1978-08-29

A method of separating isotopes based on photoselective electron capture dissociation of molecules having an electron capture cross section dependence on the vibrational state of the molecule. A molecular isotope source material is irradiated to selectively excite those molecules containing a desired isotope to a predetermined vibrational state having associated therewith an electron capture energy region substantially non-overlapping with the electron capture energy ranges associated with the lowest vibration states of the molecules. The isotope source is also subjected to electrons having an energy corresponding to the non-overlapping electron capture region whereby the selectively excited molecules preferentially capture electrons and dissociate into negative ions and neutrals. The desired isotope may be in the negative ion product or in the neutral product depending upon the mechanism of dissociation of the particular isotope source used. The dissociation product enriched in the desired isotope is then separated from the reaction system by conventional means. Specifically, .sup.235 UF.sub.6 is separated from a UF.sub.6 mixture by selective excitation followed by dissociative electron capture into .sup.235 UF.sub.5 - and F.

Isotope separation by photodissociation of Van der Waal's molecules

DOEpatents

Lee, Yuan T.

1977-01-01

A method of separating isotopes based on the dissociation of a Van der Waal's complex. A beam of molecules of a Van der Waal's complex containing, as one partner of the complex, a molecular species in which an element is present in a plurality of isotopes is subjected to radiation from a source tuned to a frequency which will selectively excite vibrational motion by a vibrational transition or through electronic transition of those complexed molecules of the molecular species which contain a desired isotope. Since the Van der Waal's binding energy is much smaller than the excitational energy of vibrational motion, the thus excited Van der Waal's complex dissociate into molecular components enriched in the desired isotope. The recoil velocity associated with vibrational to translational and rotational relaxation will send the separated molecules away from the beam whereupon the product enriched in the desired isotope can be separated from the constituents of the beam.

Separation of sulfur isotopes

DOEpatents

DeWitt, Robert; Jepson, Bernhart E.; Schwind, Roger A.

1976-06-22

Sulfur isotopes are continuously separated and enriched using a closed loop reflux system wherein sulfur dioxide (SO.sub.2) is reacted with sodium hydroxide (NaOH) or the like to form sodium hydrogen sulfite (NaHSO.sub.3). Heavier sulfur isotopes are preferentially attracted to the NaHSO.sub.3, and subsequently reacted with sulfuric acid (H.sub.2 SO.sub.4) forming sodium hydrogen sulfate (NaHSO.sub.4) and SO.sub.2 gas which contains increased concentrations of the heavier sulfur isotopes. This heavy isotope enriched SO.sub.2 gas is subsequently separated and the NaHSO.sub.4 is reacted with NaOH to form sodium sulfate (Na.sub.2 SO.sub.4) which is subsequently decomposed in an electrodialysis unit to form the NaOH and H.sub.2 SO.sub.4 components which are used in the aforesaid reactions thereby effecting sulfur isotope separation and enrichment without objectionable loss of feed materials.

Influence of liquid structure on diffusive isotope separation in molten silicates and aqueous solutions

NASA Astrophysics Data System (ADS)

Watkins, James M.; DePaolo, Donald J.; Ryerson, Frederick J.; Peterson, Brook T.

2011-06-01

Molecular diffusion in natural volcanic liquids discriminates between isotopes of major ions (e.g., Fe, Mg, Ca, and Li). Although isotope separation by diffusion is expected on theoretical grounds, the dependence on mass is highly variable for different elements and in different media. Silicate liquid diffusion experiments using simple liquid compositions were carried out to further probe the compositional dependence of diffusive isotopic discrimination and its relationship to liquid structure. Two diffusion couples consisting of the mineral constituents anorthite (CaAl 2Si 2O 8; denoted AN), albite (NaAlSi 3O 8; denoted AB), and diopside (CaMgSi 2O 6; denoted DI) were held at 1450 °C for 2 h and then quenched to ambient pressure and temperature. Major-element as well as Ca and Mg isotope profiles were measured on the recovered quenched glasses. In both experiments, Ca diffuses rapidly with respect to Si. In the AB-AN experiment, D Ca/ D Si ≈ 20 and the efficiency of isotope separation for Ca is much greater than in natural liquid experiments where D Ca/ D Si ≈ 1. In the AB-DI experiment, D Ca/ D Si ≈ 6 and the efficiency of isotope separation is between that of the natural liquid experiments and the AB-AN experiment. In the AB-DI experiment, D Mg/ D Si ≈ 1 and the efficiency of isotope separation for Mg is smaller than it is for Ca yet similar to that observed for Mg in natural liquids. The results from the experiments reported here, in combination with results from natural volcanic liquids, show clearly that the efficiency of diffusive separation of Ca isotopes is systematically related to the solvent-normalized diffusivity - the ratio of the diffusivity of the cation ( D Ca) to the diffusivity of silicon ( D Si). The results on Ca isotopes are consistent with available data on Fe, Li, and Mg isotopes in silicate liquids, when considered in terms of the parameter D cation/ D Si. Cations diffusing in aqueous solutions display a similar relationship between isotopic separation efficiency and Dcation/D, although the efficiencies are smaller than in silicate liquids. Our empirical relationship provides a tool for predicting the magnitude of diffusive isotopic effects in many geologic environments and a basis for a more comprehensive theory of isotope separation in liquid solutions. We present a conceptual model for the relationship between diffusivity and liquid structure that is consistent with available data.

Method for sequential injection of liquid samples for radioisotope separations

DOEpatents

Egorov, Oleg B.; Grate, Jay W.; Bray, Lane A.

2000-01-01

The present invention is a method of separating a short-lived daughter isotope from a longer lived parent isotope, with recovery of the parent isotope for further use. Using a system with a bi-directional pump and one or more valves, a solution of the parent isotope is processed to generate two separate solutions, one of which contains the daughter isotope, from which the parent has been removed with a high decontamination factor, and the other solution contains the recovered parent isotope. The process can be repeated on this solution of the parent isotope. The system with the fluid drive and one or more valves is controlled by a program on a microprocessor executing a series of steps to accomplish the operation. In one approach, the cow solution is passed through a separation medium that selectively retains the desired daughter isotope, while the parent isotope and the matrix pass through the medium. After washing this medium, the daughter is released from the separation medium using another solution. With the automated generator of the present invention, all solution handling steps necessary to perform a daughter/parent radionuclide separation, e.g. Bi-213 from Ac-225 "cow" solution, are performed in a consistent, enclosed, and remotely operated format. Operator exposure and spread of contamination are greatly minimized compared to the manual generator procedure described in U.S. patent application Ser. No. 08/789,973, now U.S. Pat. No. 5,749,042, herein incorporated by reference. Using 16 mCi of Ac-225 there was no detectable external contamination of the instrument components.

Mass dependence of calcium isotope fractionations in crown-ether resin chromatography.

PubMed

Fujii, Yasuhiko; Nomura, Masao; Kaneshiki, Tositaka; Sakuma, Yoichi; Suzuki, Tatsuya; Umehara, Saori; Kishimoto, Tadahumi

2010-06-01

Benzo 18-crown-6-ether resin was synthesised by the phenol condensation polymerisation process in porous silica beads, of which particle diameter was ca 60micro Calcium adsorption chromatography was performed with the synthesised resin packed in a glass column. The effluent was sampled in fractions, and the isotopic abundance ratios of (42)Ca, (43)Ca, (44)Ca, and (48)Ca against (40)Ca were measured by a thermo-ionisation mass spectrometer. The enrichment of heavier calcium isotopes was observed at the front boundary of calcium adsorption chromatogram. The mass dependence of mutual separation of calcium isotopes was analysed by using the three-isotope-plots method. The slopes of three-isotope-plots indicate the relative values of mutual separation coefficients for concerned isotopic pairs. The results have shown the normal mass dependence; isotope fractionation is proportional to the reduced mass difference, (M - M')/MM', where M and M' are masses of heavy and light isotope, respectively. The mass dependence clarifies that the isotope fractionations are originated from molecular vibration. The observed separation coefficient epsilon is 3.1x10(-3) for the pair of (40)Ca and (48)Ca. Productivity of enriched (48)Ca by crown-ether-resin was discussed as the function of the separation coefficient and the height equivalent to the theoretical plate.

Laser isotope separation

DOEpatents

Robinson, C.P.; Reed, J.J.; Cotter, T.P.; Boyer, K.; Greiner, N.R.

1975-11-26

A process and apparatus for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light is described. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photolysis, photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photolysis, photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium.

Photochemical isotope separation

DOEpatents

Robinson, C.P.; Jensen, R.J.; Cotter, T.P.; Greiner, N.R.; Boyer, K.

1987-04-28

A process is described for separating isotopes by selective excitation of isotopic species of a volatile compound by tuned laser light. A highly cooled gas of the volatile compound is produced in which the isotopic shift is sharpened and defined. Before substantial condensation occurs, the cooled gas is irradiated with laser light precisely tuned to a desired wavelength to selectively excite a particular isotopic species in the cooled gas. The laser light may impart sufficient energy to the excited species to cause it to undergo photochemical reaction or even to photoionize. Alternatively, a two-photon irradiation may be applied to the cooled gas to induce photochemical reaction or photoionization. The process is particularly applicable to the separation of isotopes of uranium and plutonium. 8 figs.

Selective IR multiphoton dissociation of molecules in a pulsed gas-dynamically cooled molecular flow interacting with a solid surface as an alternative to low-energy methods of molecular laser isotope separation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Makarov, G N; Petin, A N

2016-03-31

We report the results of studies on the isotope-selective infrared multiphoton dissociation (IR MFD) of SF{sub 6} and CF{sub 3}I molecules in a pulsed, gas-dynamically cooled molecular flow interacting with a solid surface. The productivity of this method in the conditions of a specific experiment (by the example of SF{sub 6} molecules) is evaluated. A number of low-energy methods of molecular laser isotope separation based on the use of infrared lasers for selective excitation of molecules are analysed and their productivity is estimated. The methods are compared with those of selective dissociation of molecules in the flow interacting with amore » surface. The advantages of this method compared to the low-energy methods of molecular laser isotope separation and the IR MPD method in the unperturbed jets and flows are shown. It is concluded that this method could be a promising alternative to the low-energy methods of molecular laser isotope separation. (laser separation of isotopes)« less

Highly effective hydrogen isotope separation in nanoporous metal-organic frameworks with open metal sites: direct measurement and theoretical analysis.

PubMed

Oh, Hyunchul; Savchenko, Ievgeniia; Mavrandonakis, Andreas; Heine, Thomas; Hirscher, Michael

2014-01-28

Separating gaseous mixtures that consist of very similar size is one of the critical issues in modern separation technology. Especially, the separation of the isotopes hydrogen and deuterium requires special efforts, even though these isotopes show a very large mass ratio. Conventionally, H/D separation can be realized through cryogenic distillation of the molecular species or the Girdler-sulfide process, which are among the most energy-intensive separation techniques in the chemical industry. However, costs can be significantly reduced by using highly mass-selective nanoporous sorbents. Here, we describe a hydrogen isotope separation strategy exploiting the strongly attractive open metal sites present in nanoporous metal-organic frameworks of the CPO-27 family (also referred to as MOF-74). A theoretical analysis predicts an outstanding hydrogen isotopologue separation at open metal sites due to isotopal effects, which has been directly observed through cryogenic thermal desorption spectroscopy. For H2/D2 separation of an equimolar mixture at 60 K, the selectivity of 12 is the highest value ever measured, and this methodology shows extremely high separation efficiencies even above 77 K. Our theoretical results imply also a high selectivity for HD/H2 separation at similar temperatures, and together with catalytically active sites, we propose a mechanism to produce D2 from HD/H2 mixtures with natural or enriched deuterium content.

Area Handbook Series: Islands of the Commonwealth Caribbean; A Regional Study

DTIC Science & Technology

1989-01-01

and to improve the satis- fying of basic needs and the quality of life through improved housing, nutrition , education, and environmental conditions...hospitals. Community health aides, positions deemphasized in the 1980s, served to educate the public on nutrition , infant care, family planning, and first...Caribbean Food and Nutrition Institute, at the UWI, also served regional research pur- poses. A national blood bank was located in Kingston. Economy Jamaica

Liquid Surface Levitation Holography. Part 1. Theoretical Analysis.

DTIC Science & Technology

1980-08-11

mass and momentum conservation equations. The inequality Plt >> YV I2hi," in conjunction with the relation hla - 0(Via/ao,,) requires that ,/poC2 a...in the upper fluid be given by r fu = f 4u(wi, w) e2lr i )y e2briO e- i didoi. ( B27 ) The boundary condition ,z = i’ at z = 0 gives = 4At Ybi 2poA

Great Lakes Research Review, 1982. Appendices.

DTIC Science & Technology

1982-11-01

Annul Report - societal impact of the Cladophora problem (p. 6) - long-term, large-scale drift and dispersal pattern; ii the Greit akes (p. 7) C...Nutrient Exchange Processes in Macrophyte Lakes 155 C 479 NWRI Cladophora in the Great Lakes 156 C 494 NWRI Lake Ontario Nutrient Assessment Study (LONAS...Ingested with Drinking Water 136 A 387 UM Cladophora Measurements using Remote Sensing 137 A 387 U.WI. Nutrition of Great Lakes Cladophora 138 A 393

Liquid-phase thermal diffusion isotope separation apparatus and method having tapered column

DOEpatents

Rutherford, William M.

1988-05-24

A thermal diffusion counterflow method and apparatus for separating isotopes in solution in which the solution is confined in a long, narrow, vertical slit which tapers from bottom to top. The variation in the width of the slit permits maintenance of a stable concentration distribution with relatively long columns, thus permitting isotopic separation superior to that obtainable in the prior art.

Liquid-phase thermal diffusion isotope separation apparatus and method having tapered column

DOEpatents

Rutherford, W.M.

1985-12-04

A thermal diffusion counterflow method and apparatus for separating isotopes in solution in which the solution is confined in a long, narrow, vertical slit which tapers from bottom to top. The variation in the width of the slit permits maintenance of a stable concentration distribution with relatively long columns, thus permitting isotopic separation superior to that obtained in the prior art.

Method for isotope separation by photodeflection

DOEpatents

Bernhardt, Anthony F.

1977-01-01

In the method of separating isotopes wherein a desired isotope species is selectively deflected out of a beam of mixed isotopes by irradiating the beam with a directed beam of light of narrowly defined frequency which is selectively absorbed by the desired species, the improvement comprising irradiating the deflected beam with light from other light sources whose frequencies are selected to cause the depopulation of any metastable excited states.

Mathematical modeling of filling of gas centrifuge cascade for nickel isotope separation by various feed flow rate

NASA Astrophysics Data System (ADS)

Ushakov, Anton; Orlov, Alexey; Sovach, Victor P.

2018-03-01

This article presents the results of research filling of gas centrifuge cascade for separation of the multicomponent isotope mixture with process gas by various feed flow rate. It has been used mathematical model of the nonstationary hydraulic and separation processes occurring in the gas centrifuge cascade. The research object is definition of the regularity transient of nickel isotopes into cascade during filling of the cascade. It is shown that isotope concentrations into cascade stages after its filling depend on variable parameters and are not equal to its concentration on initial isotope mixture (or feed flow of cascade). This assumption is used earlier any researchers for modeling such nonstationary process as set of steady-state concentration of isotopes into cascade. Article shows physical laws of isotope distribution into cascade stage after its filling. It's shown that varying each parameters of cascade (feed flow rate, feed stage number or cascade stage number) it is possible to change isotope concentration on output cascade flows (light or heavy fraction) for reduction of duration of further process to set of steady-state concentration of isotopes into cascade.

Dispersion curve estimation via a spatial covariance method with ultrasonic wavefield imaging.

PubMed

Chong, See Yenn; Todd, Michael D

2018-05-01

Numerous Lamb wave dispersion curve estimation methods have been developed to support damage detection and localization strategies in non-destructive evaluation/structural health monitoring (NDE/SHM) applications. In this paper, the covariance matrix is used to extract features from an ultrasonic wavefield imaging (UWI) scan in order to estimate the phase and group velocities of S0 and A0 modes. A laser ultrasonic interrogation method based on a Q-switched laser scanning system was used to interrogate full-field ultrasonic signals in a 2-mm aluminum plate at five different frequencies. These full-field ultrasonic signals were processed in three-dimensional space-time domain. Then, the time-dependent covariance matrices of the UWI were obtained based on the vector variables in Cartesian and polar coordinate spaces for all time samples. A spatial covariance map was constructed to show spatial correlations within the full wavefield. It was observed that the variances may be used as a feature for S0 and A0 mode properties. The phase velocity and the group velocity were found using a variance map and an enveloped variance map, respectively, at five different frequencies. This facilitated the estimation of Lamb wave dispersion curves. The estimated dispersion curves of the S0 and A0 modes showed good agreement with the theoretical dispersion curves. Copyright © 2018 Elsevier B.V. All rights reserved.

Integrated Extraction Chromatographic Separation of the Lithophile Elements Involved in Long-Lived Radiogenic Isotope Systems (Rb-Sr, U-Th-Pb, Sm-Nd, La-Ce, and Lu-Hf) Useful in Geochemical and Environmental Sciences.

PubMed

Pin, Christian; Gannoun, Abdelmouhcine

2017-02-21

A fast and efficient sample preparation method in view of isotope ratio measurements is described, allowing the separation of 11 elements involved, either as "parent" or as "daughter" isotopes, in six radiogenic isotope systems used as chronometers and tracers in earth, planetary, and environmental sciences. The protocol is based on small extraction chromatographic columns, used either alone or in tandem, through which a single nitric acid solution is passed, without any intervening evaporation step. The columns use commercially available extraction resins (Sr resin, TRU resin, Ln resin, RE resin, and again Ln resin for isolating Sr and Pb, LREE then La-Ce-Nd-Sm, Lu(Yb), and Hf, Th, and U, respectively) along with an additional, in-house prepared resin for separating Rb. A simplified scheme is proposed for samples requiring the separation of Sr, Pb, Nd, and Hf only. Adverse effects of troublesome major elements (Fe 3+ , Ti) are circumvented by masking with ascorbic acid and hydrofluoric acid, respectively. Typical recoveries in the 85-95% range are achieved, with procedural blanks of 10-100 pg, negligible with regard to the amounts of analytes processed. The fractions separated are suitable for high precision isotope ratio measurements by TIMS or MC-ICP-MS, as demonstrated by the repeat analyses of several international reference materials of basaltic composition for 87 Sr/ 86 Sr, 208,207,206 Pb/ 204 Pb, 143 Nd/ 144 Nd, 176 Hf/ 177 Hf, and 230 Th/ 232 Th. Concentration data could be obtained by spiking and equilibrating the sample with appropriate isotopic tracers before the onset of the separation process and, finally, measuring the isotope ratios modified by the isotope dilution process.

Development of Improved Burnable Poisons for Commercial Nuclear Power Reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. L. Grossbeck J-P.A. Renier Tim Bigelow

2003-09-30

Burnable poisons are used in nuclear reactors to produce a more level distribution of power in the reactor core and to reduce to necessity for a large control system. An ideal burnable poison would burn at the same rate as the fuel. In this study, separation of neutron-absorbing isotopes was investigated in order to eliminate isotopes that remain as absorbers at the end of fuel life, thus reducing useful fuel life. The isotopes Gd-157, Dy-164, and Er-167 were found to have desirable properties. These isotopes were separated from naturally occurring elements by means of plasma separation to evaluate feasibility andmore » cost. It was found that pure Gd-157 could save approximately $6 million at the end of four years. However, the cost of separation, using the existing facility, made separation cost- ineffective. Using a magnet with three times the field strength is expected to reduce the cost by a factor of ten, making isotopically separated burnable poisons a favorable method of increasing fuel life in commercial reactors, in particular Generation-IV reactors. The project also investigated various burnable poison configurations, and studied incorporation of metallic burnable poisons into fuel cladding.« less

Accuracy of delta 18O isotope ratio measurements on the same sample by continuous-flow isotope-ratio mass spectrometry

USDA-ARS?s Scientific Manuscript database

The doubly labeled water method is considered the reference method to measure energy expenditure. Conventional mass spectrometry requires a separate aliquot of the same sample to be prepared and analyzed separately. With continuous-flow isotope-ratio mass spectrometry, the same sample could be analy...

Atomic vapor laser isotope separation process

DOEpatents

Wyeth, R.W.; Paisner, J.A.; Story, T.

1990-08-21

A laser spectroscopy system is utilized in an atomic vapor laser isotope separation process. The system determines spectral components of an atomic vapor utilizing a laser heterodyne technique. 23 figs.

Isotopic separation of acetaldehyde and methanol from their deuterated isotopologues on a porous layer open tubular column allows quantification by stable isotope dilution without mass spectrometric detection.

PubMed

Schmarr, Hans-Georg; Wacker, Michael; Mathes, Maximilian

2017-01-20

An isotopic separation of acetaldehyde and acetaldehyde-2,2,2-d3 was achieved in a temperature programmed run on a porous layer open tubular (PLOT) capillary column coated with particles of divinylbenzene ethylene glycol/dimethylacrylate (Rt ® -U-BOND). This is the prerequisite for the development of quantitative analytical methods based on a stable isotope dilution assay (SIDA) without a mass spectrometric detection (non-MS SIDA). For routine analysis a flame ionization detector (FID) can thus be applied as a robust and low-cost alternative. In a preliminary study, static headspace extraction and gas chromatographic separation (HS-GC-FID) of acetaldehyde in aqueous solutions was shown as an application. Good linearity was obtained in a calibration range from 0.4 to 40mgL -1 , with peak integration benefitting from the inverse isotope effect encountered on the specific porous polymer. Furthermore, separation of methanol and deuterated methanol (d3) could also be achieved under the same chromatographic conditions. The achieved isotopic separation of these important volatile compounds now allows non-MS SIDA-based methods that are still to be developed. Copyright © 2016 Elsevier B.V. All rights reserved.

Possible application of laser isotope separation

NASA Technical Reports Server (NTRS)

Delionback, L. M.

1975-01-01

The laser isotope separation process is described and its special economic features discussed. These features are its low cost electric power operation, capital investment costs, and the costs of process materials.

Can the waiting-point nucleus 78Ni be studied at an on-line mass-separator?

NASA Astrophysics Data System (ADS)

Wöhr, A.; Andreyev, A.; Bijnens, N.; Breitenbach, J.; Franchoo, S.; Huyse, M.; Kudryavtsev, Y. A.; Piechaczek, A.; Raabe, R. R.; Reusen, I.; Vermeeren, L.; Van Duppen, P.

1997-02-01

Short-lived nickel isotopes have been studied using a chemically selective Ion Guide Laser Ion Source (IGLIS) based on resonance ionisation of atoms at the Leuven Isotope Separator On-Line (LISOL) separator. The decay properties of different Ni isotopes have been studied using β-γ-coincidences. Experimental production rates of proton induced fission of 238U are obtained for 69,71Ni. These numbers are in a strong disagreement with Silberg-Tsao calculations.

Isotope Separation in Concurrent Gas Centrifuges

NASA Astrophysics Data System (ADS)

Bogovalov, S. V.; Borman, V. D.

An analytical equation defining separative power of an optimized concurrent gas centrifuge is obtained for an arbitrary binary mixture of isotopes. In the case of the uranium isotopes the equation gives δU= 12.7(V/700 m/s)2(300 K/T)L, kg SWU/yr, where L and V are the length and linear velocity of the rotor of the gas centrifuge, T is the temperature. This formula well agrees with an empirical separative power of counter current gas centrifuges.

Isotopy of the hydrosphere

NASA Astrophysics Data System (ADS)

Ferronskii, V. I.; Poliakov, V. A.

This book is concerned with the natural relations regarding the distribution of the stable isotopes of hydrogen and oxygen in the hydrosphere, taking into account the most important problems with respect to the dynamics and the origin of waters. The solution of these problems on an isotopic basis is considered. The physicochemical principles of isotope separation are discussed along with the isotopic composition of atmospheric moisture, the isotopic composition of surface continental waters, the hydrogen and oxygen isotopic composition of minerals of magmatic and metamorphic rocks and fluid inclusions, the isotopic composition of groundwaters of modern volcanic regions, and the origin of the earth's hydrosphere in the light of isotopic, cosmochemical, and theoretical studies. Attention is also given to the separation of hydrogen and oxygen isotopes of waters in the underground cycle, the isotopic composition of the deep-formation waters of sedimentary basins, the relationship between surface and ground waters, and the groundwater residence time in an aquifer.

High Throughput Strontium Isotope Method for Monitoring Fluid Flow Related to Geological CO2 Storage

NASA Astrophysics Data System (ADS)

Capo, R. C.; Wall, A. J.; Stewart, B. W.; Phan, T. T.; Jain, J. C.; Hakala, J. A.; Guthrie, G. D.

2012-12-01

Natural isotope tracers, such as strontium (Sr), can be a unique and powerful component of a monitoring strategy at a CO2 storage site, facilitating both the quantification of reaction progress for fluid-rock interactions and the tracking of brine migration caused by CO2 injection. Several challenges must be overcome, however, to enable the routine use of isotopic tracers, including the ability to rapidly analyze numerous aqueous samples with potentially complex chemical compositions. In a field situation, it might be necessary to analyze tens of samples over a short period of time to identify subsurface reactions and respond to unexpected fluid movement in the host formation. These conditions require streamlined Sr separation chemistry for samples ranging from pristine groundwaters to those containing high total dissolved solids, followed by rapid measurement of isotope ratios with high analytical precision. We have optimized Sr separation chemistry and MC-ICP-MS methods to provide rapid and precise measurements of isotope ratios in geologic, hydrologic, and environmental samples. These improvements will allow an operator to independently prepare samples for Sr isotope analysis off-site using fast, low cost chemical separation procedures and commercially available components. Existing vacuum-assisted Sr separation procedures were modified by using inexpensive disposable parts to eliminate cross contamination. Experimental results indicate that the modified columns provide excellent separation of Sr from chemically complex samples and that Sr can be effectively isolated from problematic matrix elements (e.g., Ca, Ba, K) associated with oilfield brines and formation waters. The separation procedure is designed for high sample throughput in which batches of 24 samples can be processed in approximately 2 hours, and are ready for Sr isotope measurements by MC-ICP-MS immediately after collection from the columns. Precise Sr isotope results can be achieved by MC-ICP-MS with a throughput of 4 to 5 samples per hour. Our mean measured value of NIST Sr isotope standard SRM 987 is 0.710265 ± 0.000014 (2σ, n = 94). A range of brines and CO2-rich fluids analyzed by this method yielded results within the analytical uncertainty of 87Sr/86Sr ratios previously determined by standard column separation and thermal ionization mass spectrometry. This method provides a fast and effective way to use Sr isotopes for monitoring purposes related to geological CO2 storage.

Separation efficiency of the MASHA facility for short-lived mercury isotopes

NASA Astrophysics Data System (ADS)

Rodin, A. M.; Belozerov, A. V.; Chernysheva, E. V.; Dmitriev, S. N.; Gulyaev, A. V.; Gulyaeva, A. V.; Itkis, M. G.; Kliman, J.; Kondratiev, N. A.; Krupa, L.; Novoselov, A. S.; Oganessian, Yu. Ts.; Podshibyakin, A. V.; Salamatin, V. S.; Siváček, I.; Stepantsov, S. V.; Vanin, D. V.; Vedeneev, V. Yu.; Yukhimchuk, S. A.; Granja, C.; Pospisil, S.

2014-06-01

The mass-separator MASHA built to identify Super Heavy Elements by their mass-to-charge ratios is described. The results of the off- and on-line measurements of its separation efficiency are presented. In the former case four calibrated leaks of noble gases were used. In the latter the efficiency was measured via 284 MeV Ar beam and with using the hot catcher. The ECR ion source was used in both cases. The -radioactive isotopes of mercury produced in the complete fusion reaction Ar+SmHg+xn were detected at the mass-separator focal plane. The half-lives and the separation efficiency for the short-lived mercury isotopes were measured. Potentialities of the MEDIPIX detector system have been demonstrated for future use at the mass-separator MASHA.

VELOCITY SELECTOR METHOD FOR THE SEPARATION OF ISOTOPES

DOEpatents

Britten, R.J.

1957-12-31

A velocity selector apparatus is described for separating and collecting an enriched fraction of the isotope of a particular element. The invention has the advantage over conventional mass spectrometers in that a magnetic field is not used, doing away with the attendant problems of magnetic field variation. The apparatus separates the isotopes by selectively accelerating the ionized constituents present in a beam of the polyisotopic substance that are of uniform kinetic energy, the acceleration being applied intermittently and at spaced points along the beam and in a direction normal to the direction of the propagation of the uniform energy beam whereby a transverse displacement of the isotopic constituents of different mass is obtained.

System for recovery of daughter isotopes from a source material

DOEpatents

Tranter, Troy J [Idaho Falls, ID; Todd, Terry A [Aberdeen, ID; Lewis, Leroy C [Idaho Falls, ID; Henscheid, Joseph P [Idaho Falls, ID

2009-08-04

A method of separating isotopes from a mixture containing at least two isotopes in a solution is disclosed. A first isotope is precipitated and is collected from the solution. A daughter isotope is generated and collected from the first isotope. The invention includes a method of producing an actinium-225/bismuth-213 product from a material containing thorium-229 and thorium-232. A solution is formed containing nitric acid and the material containing thorium-229 and thorium-232, and iodate is added to form a thorium iodate precipitate. A supernatant is separated from the thorium iodate precipitate and a second volume of nitric acid is added to the thorium iodate precipitate. The thorium iodate precipitate is stored and a decay product comprising actinium-225 and bismuth-213 is generated in the second volume of nitric acid, which is then separated from the thorium iodate precipitate, filtered, and treated using at least one chromatographic procedure. A system for producing an actinium-225/bismuth-213 product is also disclosed.

Water isotope partitioning and ecohydrologic separation in mixed conifer forest explored with a centrifugation water extraction method

NASA Astrophysics Data System (ADS)

Bowers, W.; Mercer, J.; Pleasants, M.; Williams, D. G.

2017-12-01

Isotopic partitioning of water within soil into tightly and loosely bound fractions has been proposed to explain differences between isotopic water sources used by plants and those that contribute to streams and ground water, the basis for the "two water worlds" hypothesis. We examined the isotope ratio values of water in trees, bulk soil, mobile water collected from soil lysimeters, stream water, and GW at three different hillslopes in a mixed conifer forest in southeastern Wyoming, USA. Hillslopes differed in aspect and topographic position with corresponding differences in surface energy balance, snowmelt timing, and duration of soil moisture during the dry summer. The isotopic results support the partitioning of water within the soil; trees apparently used a different pool of water for transpiration than that recovered from soil lysimeters and the source was not resolved with the isotopic signature of the water that was extracted from bulk soil via cryogenic vacuum distillation. Separating and measuring the isotope ratios values in these pools would test the assumption that the tightly bound water within the soil has the same isotopic signature as the water transpired by the trees. We employed a centrifugation approach to separate water within the soil held at different tensions by applying stepwise increases in rotational velocity and pressures to the bulk soil samples. Effluent and the remaining water (cryogenically extracted) at each step were compared. We first applied the centrifugation method in a simple lab experiment using sandy loam soil and separate introductions of two isotopically distinct waters. We then applied the method to soil collected from the montane hillslopes. For the lab experiment, we predicted that effluents would have distinct isotopic signatures, with the last effluent and extracted water more closely representing the isotopic signature of the first water applied. For our field samples, we predicted that the isotopic signature of the water discharged in the last centrifuge step and final extraction would more closely represent the isotopic signature of water extracted from trees. Understanding the isotopic partitioning of water within soil is important for interpreting plant water isotope values within the context of the "two water worlds" hypothesis.

Infrared Lasers in Chemistry.

ERIC Educational Resources Information Center

John, Phillip

1982-01-01

Selected infrared laser chemistry topics are discussed including carbon dioxide lasers, infrared quanta and molecules, laser-induced chemistry, structural isomerization (laser purification, sensitized reactions, and dielectric breakdown), and fundamental principles of laser isotope separation, focusing on uranium isotope separation. (JN)

Separation of the isotopes of boron by chemical exchange reactions

DOEpatents

McCandless, Frank P.; Herbst, Ronald S.

1995-01-01

The isotopes of boron, .sup.10 B and .sup.11 B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF.sub.3 and a liquid BF.sub.3 . donor molecular addition complex formed between BF.sub.3 gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone.

Isotopic determinations of rhenium and osmium in meteorites by using fusion, distillation and ion-exchange separations

USGS Publications Warehouse

Morgan, J.W.; Walker, R.J.

1989-01-01

A stable isotope-dilution method using resonance ionization mass spectrometry is suitable for the determination of rhenium and osmium abundances and osmium isotopic composition in carbonaceous chondrites and iron meteorites. The chemical procedure involves sodium peroxide fusion, followed by distillation of osmium from sulfuric acid/hydrogen peroxide and subsequent anion-exchange separation of rhenium from the same solution. ?? 1989.

Device and method for separating oxygen isotopes

DOEpatents

Rockwood, Stephen D.; Sander, Robert K.

1984-01-01

A device and method for separating oxygen isotopes with an ArF laser which produces coherent radiation at approximately 193 nm. The output of the ArF laser is filtered in natural air and applied to an irradiation cell where it preferentially photodissociates molecules of oxygen gas containing .sup.17 O or .sup.18 O oxygen nuclides. A scavenger such as O.sub.2, CO or ethylene is used to collect the preferentially dissociated oxygen atoms and recycled to produce isotopically enriched molecular oxygen gas. Other embodiments utilize an ArF laser which is narrowly tuned with a prism or diffraction grating to preferentially photodissociate desired isotopes. Similarly, desired mixtures of isotopic gas can be used as a filter to photodissociate enriched preselected isotopes of oxygen.

Separation of the isotopes of boron by chemical exchange reactions

DOEpatents

McCandless, F.P.; Herbst, R.S.

1995-05-30

The isotopes of boron, {sup 10}B and {sup 11}B, are separated by means of a gas-liquid chemical exchange reaction involving the isotopic equilibrium between gaseous BF{sub 3} and a liquid BF{sub 3} donor molecular addition complex formed between BF{sub 3} gas and a donor chosen from the group consisting of: nitromethane, acetone, methyl isobutyl ketone, or diisobutyl ketone. 1 Fig.

Separation of the Isotopes of Calcium by Countercurrent Electromigration in Fused Salts. Final Report; SEPARATION DES ISOTOPES DU CALCIUM PAR ELECTROMIGRATION A CONTRE COURANT EN SELS FONDUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menes, F.; Dirian, G.

1962-12-14

The results obtained up to June 25, 1962, on the separation of Ca isotopes by electromigration in fused salts have been reported in seven progress reports. The data given in these reports are summarized. Later study investigated the improvement of the diaphragm performance using nonclassical methods, preparation of an experiment confirming the performances of the high capacity U tube'' apparatus, and preparation of an installation designed for perfecting the dropping tube'' device. Only preliminary results on these studes are available. (J.S.R.)

ISOTOPE SEPARATORS

DOEpatents

Bacon, C.G.

1958-08-26

An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

New triple oxygen isotope data of bulk and separated fractions from SNC meteorites: Evidence for mantle homogeneity of Mars

NASA Astrophysics Data System (ADS)

Ali, Arshad; Jabeen, Iffat; Gregory, David; Verish, Robert; Banerjee, Neil R.

2016-05-01

We report precise triple oxygen isotope data of bulk materials and separated fractions of several Shergotty-Nakhla-Chassigny (SNC) meteorites using enhanced laser-assisted fluorination technique. This study shows that SNCs have remarkably identical Δ17O and a narrow range in δ18O values suggesting that these meteorites have assimilated negligibly small surface materials (<5%), which is undetectable in the oxygen isotope compositions reported here. Also, fractionation factors in coexisting silicate mineral pairs (px-ol and mask-ol) further demonstrate isotopic equilibrium at magmatic temperatures. We present a mass-dependent fractionation line for bulk materials with a slope of 0.526 ± 0.016 (1SE) comparable to the slope obtained in an earlier study (0.526 ± 0.013; Franchi et al. 1999). We also present a new Martian fractionation line for SNCs constructed from separated fractions (i.e., pyroxene, olivine, and maskelynite) with a slope of 0.532 ± 0.009 (1SE). The identical fractionation lines run above and parallel to our terrestrial fractionation line with Δ17O = 0.318 ± 0.016‰ (SD) for bulk materials and 0.316 ± 0.009‰ (SD) for separated fractions. The conformity in slopes and Δ17O between bulk materials and separated fractions confirm oxygen isotope homogeneity in the Martian mantle though recent studies suggest that the Martian lithosphere may potentially have multiple oxygen isotope reservoirs.

Separation of copper, iron, and zinc from complex aqueous solutions for isotopic measurement

USGS Publications Warehouse

Borrok, D.M.; Wanty, R.B.; Ridley, W.I.; Wolf, R.; Lamothe, P.J.; Adams, M.

2007-01-01

The measurement of Cu, Fe, and Zn isotopes in natural samples may provide valuable information about biogeochemical processes in the environment. However, the widespread application of stable Cu, Fe, and Zn isotope chemistry to natural water systems remains limited by our ability to efficiently separate these trace elements from the greater concentrations of matrix elements. In this study, we present a new method for the isolation of Cu, Fe, and Zn from complex aqueous solutions using a single anion-exchange column with hydrochloric acid media. Using this method we are able to quantitatively separate Cu, Fe, and Zn from each other and from matrix elements in a single column elution. Elution of the elements of interest, as well as all other elements, through the anion-exchange column is a function of the speciation of each element in the various concentrations of HCl. We highlight the column chemistry by comparing our observations with published studies that have investigated the speciation of Cu, Fe, and Zn in chloride solutions. The functionality of the column procedure was tested by measuring Cu, Fe, and Zn isotopes in a variety of stream water samples impacted by acid mine drainage. The accuracy and precision of Zn isotopic measurements was tested by doping Zn-free stream water with the Zn isotopic standard. The reproducibility of the entire column separation process and the overall precision of the isotopic measurements were also evaluated. The isotopic results demonstrate that the Cu, Fe, and Zn column separates from the tested stream waters are of sufficient purity to be analyzed directly using a multicollector inductively coupled plasma mass spectrometer (MC-ICP-MS), and that the measurements are fully-reproducible, accurate, and precise. Although limited in scope, these isotopic measurements reveal significant variations in ??65Cu (- 1.41 to + 0.30???), ??56Fe (- 0.56 to + 0.34???), and ??66Zn (0.31 to 0.49???) among samples collected from different abandoned mines within a single watershed. Hence, Cu, Fe, and Zn isotopic measurements may be a powerful tool for fingerprinting specific metal sources and/or examining biogeochemical reactions within fresh water systems.

Separative analyses of a chromatographic column packed with a core-shell adsorbent for lithium isotope separation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sugiyama, T.; Sugura, K.; Enokida, Y.

2015-03-15

Lithium-6 is used as a blanket material for sufficient tritium production in DT fueled fusion reactors. A core-shell type adsorbent was proposed for lithium isotope separation by chromatography. The mass transfer model in a chromatographic column consisted of 4 steps, such as convection and dispersion in the column, transfer through liquid films, intra-particle diffusion and and adsorption or desorption at the local adsorption sites. A model was developed and concentration profiles and time variation in the column were numerically simulated. It became clear that core-shell type adsorbents with thin porous shell were saturated rapidly relatively to fully porous one andmore » established a sharp edge of adsorption band. This is very important feature because lithium isotope separation requires long-distance development of adsorption band. The values of HETP (Height Equivalent of a Theoretical Plate) for core-shell adsorbent packed column were estimated by statistical moments of the step response curve. The value of HETP decreased with the thickness of the porous shell. A core-shell type adsorbent is, then, useful for lithium isotope separation. (authors)« less

Isotope separation apparatus and method

DOEpatents

Cotter, Theodore P.

1982-12-28

The invention relates to a method and apparatus for laser isotope separation by photodeflection. A molecular beam comprising at least two isotopes to be separated intersects, preferable substantially perpendicular to one broad side of the molecular beam, with a laser beam traveling in a first direction. The laser beam is reflected back through the molecular beam, preferably in a second direction essentially opposite to the first direction. The laser beam comprises .pi.-pulses of a selected wavelength which excite unexcited molecules, or cause stimulated emission of excited molecules of one of the isotopes. Excitation caused by first direction .pi.-pulses moves molecules of the isotope excited thereby in the first direction. Stimulated emission of excited molecules of the isotope is brought about by returning .pi.-pulses traveling in the second direction. Stimulated emission moves emitting molecules in a direction opposite to the photon emitted. Because emitted photons travel in the second direction, emitting molecules move in the first direction. Substantial molecular movement is accomplished by a large number of .pi.-pulse-molecule interactions. A beam corer collects the molecules in the resulting enriched divergent portions of the beam.

Laser separation of lithium isotopes by double resonance enhanced multiphoton ionization of Li/sub 2/

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balz, J.G.; Bernheim, R.A.; Gold, L.P.

1987-01-01

Multiphoton ionization spectra of /sup 7/Li/sub 2/, /sup 6/Li/sub 2/, and /sup 7/Li/sup 6/Li vapors have been measured in the 570--650 nm region using a single, low resolution, multimode cw dye laser. A number of wavelengths provide selective multiphoton ionization of one isotopic species demonstrating the possibility of efficient laser-driven isotopic separation in lithium in this wavelength region.

10 CFR 75.4 - Definitions.

Code of Federal Regulations, 2011 CFR

2011-01-01

... to IAEA Safeguards) means the collection of environmental samples (e.g., air, water, vegetation, soil... uranium or enriching uranium in the isotope 235, zirconium tubes, heavy water or deuterium, nuclear-grade...); (3) A fuel fabrication plant; (4) An enrichment plant or isotope separation plant for the separation...

Chromatographic Separation of Cd from Plants via Anion-Exchange Resin for an Isotope Determination by Multiple Collector ICP-MS.

PubMed

Wei, Rongfei; Guo, Qingjun; Wen, Hanjie; Peters, Marc; Yang, Junxing; Tian, Liyan; Han, Xiaokun

2017-01-01

In this study, key factors affecting the chromatographic separation of Cd from plants, such as the resin column, digestion and purification procedures, were experimentally investigated. A technique for separating Cd from plant samples based on single ion-exchange chromatography has been developed, which is suitable for the high-precision analysis of Cd isotopes by multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The robustness of the technique was assessed by replicate analyses of Cd standard solutions and plant samples. The Cd yields of the whole separation process were higher than 95%, and the 114/110 Cd values of three Cd second standard solutions (Münster Cd, Spex Cd, Spex-1 Cd solutions) relative to the NIST SRM 3108 were measured accurately, which enabled the comparisons of Cd isotope results obtained in other laboratories. Hence, stable Cd isotope analyses represent a powerful tool for fingerprinting specific Cd sources and/or examining biogeochemical reactions in ecological and environmental systems.

The plasma separation process as a pre-cursor for large scale radioisotope production

NASA Astrophysics Data System (ADS)

Stevenson, Nigel R.

2001-07-01

Radioisotope production generally employs either accelerators or reactors to convert stable (usually enriched) isotopes into the desired product species. Radioisotopes have applications in industry, environmental sciences, and most significantly in medicine. The production of many potentially useful radioisotopes is significantly hindered by the lack of availability or by the high cost of key enriched stable isotopes. To try and meet this demand, certain niche enrichment processes have been developed and commercialized. Calutrons, centrifuges, and laser separation processes are some of the devices and techniques being employed to produce large quantities of selective enriched stable isotopes. Nevertheless, the list of enriched stable isotopes in sufficient quantities remains rather limited and this continues to restrict the availability of many radioisotopes that otherwise could have a significant impact on society. The Plasma Separation Process is a newly available commercial technique for producing large quantities of a wide range of enriched isotopes and thereby holds promise of being able to open the door to producing new and exciting applications of radioisotopes in the future.

Meteoritic Sulfur Isotopic Analysis

NASA Technical Reports Server (NTRS)

Thiemens, Mark H.

1996-01-01

Funds were requested to continue our program in meteoritic sulfur isotopic analysis. We have recently detected a potential nucleosynthetic sulfur isotopic anomaly. We will search for potential carriers. The documentation of bulk systematics and the possible relation to nebular chemistry and oxygen isotopes will be explored. Analytical techniques for delta(sup 33), delta(sup 34)S, delta(sup 36)S isotopic analysis were improved. Analysis of sub milligram samples is now possible. A possible relation between sulfur isotopes and oxygen was detected, with similar group systematics noted, particularly in the case of aubrites, ureilites and entstatite chondrites. A possible nucleosynthetic excess S-33 has been noted in bulk ureilites and an oldhamite separate from Norton County. High energy proton (approximately 1 GeV) bombardments of iron foils were done to experimentally determine S-33, S-36 spallogenic yields for quantitation of isotopic measurements in iron meteorites. Techniques for measurement of mineral separates were perfected and an analysis program initiated. The systematic behavior of bulk sulfur isotopes will continue to be explored.

Enhancement of Identity in the Hydraulic Characteristics of a Gas Centrifuge for Isotope Separation

NASA Astrophysics Data System (ADS)

Yatsenko, D. V.; Borisevich, V. D.; Godisov, O. N.

The problem of non-identity in characteristics of the GCs for uranium isotope separation grows up with increase of a rotor speed of rotation. It may lead to noticeable decrease of the separative power of the centrifugal machines. The carried out assessments allowed to get the dependence of the relative separation performance losses on the non-identity in the hydraulic characteristics of the GCs connected in parallel. The results of calculation are compared with that of obtained in experiments.

Apparatus for separating and recovering hydrogen isotopes

DOEpatents

Heung, Leung K.

1994-01-01

An apparatus for recovering hydrogen and separating its isotopes. The apparatus includes a housing bearing at least a fluid inlet and a fluid outlet. A baffle is disposed within the housing, attached thereto by a bracket. A hollow conduit is coiled about the baffle, in spaced relation to the baffle and the housing. The coiled conduit is at least partially filled with a hydride. The hydride can be heated to a high temperature and cooled to a low temperature quickly by circulating a heat transfer fluid in the housing. The spacing between the baffle and the housing maximizes the heat exchange rate between the fluid in the housing and the hydride in the conduit. The apparatus can be used to recover hydrogen isotopes (protium, deuterium and tritium) from gaseous mixtures, or to separate hydrogen isotopes from each other.

Stable Isotope Quantitative N-Glycan Analysis by Liquid Separation Techniques and Mass Spectrometry.

PubMed

Mittermayr, Stefan; Albrecht, Simone; Váradi, Csaba; Millán-Martín, Silvia; Bones, Jonathan

2017-01-01

Liquid phase separation analysis and subsequent quantitation remains a challenging task for protein-derived oligosaccharides due to their inherent structural complexity and diversity. Incomplete resolution or co-detection of multiple glycan species complicates peak area-based quantitation and associated statistical analysis when optical detection methods are used. The approach outlined herein describes the utilization of stable isotope variants of commonly used fluorescent tags that allow for mass-based glycan identification and relative quantitation following separation by liquid chromatography (LC) or capillary electrophoresis (CE). Comparability assessment of glycoprotein-derived oligosaccharides is performed by derivatization with commercially available isotope variants of 2-aminobenzoic acid or aniline and analysis by LC- and CE-mass spectrometry. Quantitative information is attained from the extracted ion chromatogram/electropherogram ratios generated from the light and heavy isotope clusters.

Investigation of the Photochemical Method for Uranium Isotope Separation

DOE R&D Accomplishments Database

Urey, H. C.

1943-07-10

To find a process for successful photochemical separation of isotopes several conditions have to be fulfilled. First, the different isotopes have to show some differences in the spectrum. Secondly, and equally important, this difference must be capable of being exploited in a photochemical process. Parts A and B outline the physical and chemical conditions, and the extent to which one might expect to find them fulfilled. Part C deals with the applicability of the process.

Substance use among university students at the St Augustine campus of the University of the West Indies.

PubMed

Dhanookdhary, A M; Gomez, A M; Khan, R; Lall, A; Murray, D; Prabhu, D; Ragoonath, A; Singh, N; Tewari, S; Youssef, F F

2010-12-01

Substance use and abuse is a well known public health risk that peaks in persons between 18 and 25 years of age and is prevalent among university students. While this has been repeatedly documented in developed nations, there have been limited studies in the English-speaking Caribbean. This study therefore sought to assess the prevalence of alcohol, tobacco and marijuana use among university students in the English-speaking Caribbean and any associated risk factors. The study was designed as a descriptive, cross-sectional study to assess substance use in full-time, undergraduate students of The University of the West Indies (UWI), Trinidad and Tobago, over a six-month period. Questionnaires were distributed and students asked to self-report on their use of alcohol, tobacco and marijuana during the preceding six months. The six-month prevalence rate for alcohol was 70% and 28% of students were identified as regular users. Binge drinking was estimated at 31%. Muslims were least likely to have used alcohol when compared to other religious groupings. The prevalence rate for tobacco and marijuana was 17% and 13%, respectively Ten per cent used all three substances. The use of all three substances was associated with multiple problems. We conclude that substance use is common among many students of the UWI but generally lower than reports from other regions of the world. Despite this, substance use is associated with a number of problems and immediate educational interventions may be necessary to assist students in making informed and responsible choices.

Computer literacy and attitudes of dental students and staff at the University of the West Indies Dental School.

PubMed

Smith, W; Bedayse, S; Lalwah, S L; Paryag, A

2009-08-01

The University of the West Indies (UWI) Dental School is planning to implement computer-based information systems to manage student and patient data. In order to measure the acceptance of the proposed implementation and to determine the degree of training that would be required, a survey was undertaken of the computer literacy and attitude of all staff and students. Data were collected via 230 questionnaires from all staff and students. A 78% response rate was obtained. The computer literacy of the majority of respondents was ranked as 'more than adequate' compared to other European Dental Schools. Respondents < 50 years had significantly higher computer literacy scores than older age groups (P < 0.05). Similarly, respondents who owned an email address, a computer, or were members of online social networking sites had significantly higher computer literacy scores than those who did not (P < 0.05). Sex, nationality and whether the respondent was student/staff were not significant factors. Most respondents felt that computer literacy should be a part of every modern undergraduate curriculum; that computer assisted learning applications and web-based learning activity could effectively supplement the traditional undergraduate curriculum and that a suitable information system would improve the efficiency in the school's management of students, teaching and clinics. The implementation of a computer-based information system is likely to have widespread acceptance among students and staff at the UWI Dental School. The computer literacy of the students and staff are on par with those of schools in the US and Europe.

Tritium monitor

DOEpatents

Chastagner, Philippe

1994-01-01

A system for continuously monitoring the concentration of tritium in an aqueous stream. The system pumps a sample of the stream to magnesium-filled combustion tube which reduces the sample to extract hydrogen gas. The hydrogen gas is then sent to an isotope separation device where it is separated into two groups of isotopes: a first group of isotopes containing concentrations of deuterium and tritium, and a second group of isotopes having substantially no deuterium and tritium. The first group of isotopes containing concentrations of deuterium and tritium is then passed through a tritium detector that produces an output proportional to the concentration of tritium detected. Preferably, the detection system also includes the necessary automation and data collection equipment and instrumentation for continuously monitoring an aqueous stream.

Tritium monitor

DOEpatents

Chastagner, P.

1994-06-14

A system is described for continuously monitoring the concentration of tritium in an aqueous stream. The system pumps a sample of the stream to magnesium-filled combustion tube which reduces the sample to extract hydrogen gas. The hydrogen gas is then sent to an isotope separation device where it is separated into two groups of isotopes: a first group of isotopes containing concentrations of deuterium and tritium, and a second group of isotopes having substantially no deuterium and tritium. The first group of isotopes containing concentrations of deuterium and tritium is then passed through a tritium detector that produces an output proportional to the concentration of tritium detected. Preferably, the detection system also includes the necessary automation and data collection equipment and instrumentation for continuously monitoring an aqueous stream. 1 fig.

Method for laser induced isotope enrichment

DOEpatents

Pronko, Peter P.; Vanrompay, Paul A.; Zhang, Zhiyu

2004-09-07

Methods for separating isotopes or chemical species of an element and causing enrichment of a desired isotope or chemical species of an element utilizing laser ablation plasmas to modify or fabricate a material containing such isotopes or chemical species are provided. This invention may be used for a wide variety of materials which contain elements having different isotopes or chemical species.

Measurement of plutonium isotope ratios in nuclear fuel samples by HPLC-MC-ICP-MS

NASA Astrophysics Data System (ADS)

Günther-Leopold, I.; Waldis, J. Kobler; Wernli, B.; Kopajtic, Z.

2005-04-01

Radioactive isotopes are traditionally quantified by means of radioactivity counting techniques ([alpha], [beta], [gamma]). However, these methods often require extensive matrix separation and sample purification before the identification of specific isotopes and their relative abundance is possible as it is necessary in the frame of post-irradiation examinations on nuclear fuel samples. The technique of multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) is attracting much attention because it permits the precise measurement of the isotope compositions for a wide range of elements combined with excellent limits of detection due to high ionization efficiencies. The present paper describes one of the first applications of an online high-performance liquid chromatographic separation system coupled to a MC-ICP-MS in order to overcome isobaric interferences for the determination of the plutonium isotope composition and concentrations in irradiated nuclear fuels. The described chromatographic separation is sufficient to prevent any isobaric interference between 238Pu present at trace concentrations and 238U present as the main component of the fuel samples. The external reproducibility of the uncorrected plutonium isotope ratios was determined to be between 0.04 and 0.2% (2 s) resulting in a precision in the [per mille sign] range for the isotopic vectors of the irradiated fuel samples.

Exploiting Diffusion Barrier and Chemical Affinity of Metal-Organic Frameworks for Efficient Hydrogen Isotope Separation.

PubMed

Kim, Jin Yeong; Balderas-Xicohténcatl, Rafael; Zhang, Linda; Kang, Sung Gu; Hirscher, Michael; Oh, Hyunchul; Moon, Hoi Ri

2017-10-25

Deuterium plays a pivotal role in industrial and scientific research, and is irreplaceable for various applications such as isotope tracing, neutron moderation, and neutron scattering. In addition, deuterium is a key energy source for fusion reactions. Thus, the isolation of deuterium from a physico-chemically almost identical isotopic mixture is a seminal challenge in modern separation technology. However, current commercial approaches suffer from extremely low separation efficiency (i.e., cryogenic distillation, selectivity of 1.5 at 24 K), requiring a cost-effective and large-scale separation technique. Herein, we report a highly effective hydrogen isotope separation system based on metal-organic frameworks (MOFs) having the highest reported separation factor as high as ∼26 at 77 K by maximizing synergistic effects of the chemical affinity quantum sieving (CAQS) and kinetic quantum sieving (KQS). For this purpose, the MOF-74 system having high hydrogen adsorption enthalpies due to strong open metal sites is chosen for CAQS functionality, and imidazole molecules (IM) are employed to the system for enhancing the KQS effect. To the best of our knowledge, this work is not only the first attempt to implement two quantum sieving effects, KQS and CAQS, in one system, but also provides experimental validation of the utility of this system for practical industrial usage by isolating high-purity D 2 through direct selective separation studies using 1:1 D 2 /H 2 mixtures.

Validation of Electrochemically Modulated Separations Performed On-Line with MC-ICP-MS for Uranium and Plutonium Isotopic Analyses

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liezers, Martin; Olsen, Khris B.; Mitroshkov, Alexandre V.

2010-08-11

The most time consuming process in uranium or plutonium isotopic analyses is performing the requisite chromatographic separation of the actinides. Filament preparation for thermal ionization (TIMS) adds further delays, but is generally accepted due to the unmatched performance in trace isotopic analyses. Advances in Multi-Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS) are beginning to rival the performance of TIMS. Methods, such as Electrochemically Modulated Separations (EMS) can efficiently pre-concentrate U or Pu quite selectively from small solution volumes in a matrix of 0.5 M nitric acid. When performed in-line with ICP-MS, the rapid analyte release from the electrode is fast,more » and large transient analyte signal enhancements of >100 fold can be achieved as compared to more conventional continuous nebulization of the original starting solution. This makes the approach ideal for very low level isotope ratio measurements. In this paper, some aspects of EMS performance are described. These include low level Pu isotope ratio behavior versus concentration by MC-ICP-MS and uranium rejection characteristics that are also important for reliable low level Pu isotope ratio determinations.« less

Method and apparatus for tritiated water separation

DOEpatents

Nelson, David A.; Duncan, James B.; Jensen, George A.

1995-01-01

The present invention is a membrane method and apparatus for separating isotopic water constituents from light water. The method involves providing a supported membrane of an aromatic polyphosphazene and pressurizing the water on one side of the membrane thereby forcing the light water through the supported membrane while isotopic water constituents are retained or vice versa. The apparatus of the present invention includes an aromatic polyphosphazene placed on a porous support and means for pressurizing water through the membrane while certain isotopic water constituents are retained.

Method and apparatus for tritiated water separation

DOEpatents

Nelson, D.A.; Duncan, J.B.; Jensen, G.A.

1995-09-19

The present invention is a membrane method and apparatus for separating isotopic water constituents from light water. The method involves providing a supported membrane of an aromatic polyphosphazene and pressurizing the water on one side of the membrane thereby forcing the light water through the supported membrane while isotopic water constituents are retained or vice versa. The apparatus of the present invention includes an aromatic polyphosphazene placed on a porous support and means for pressurizing water through the membrane while certain isotopic water constituents are retained. 1 fig.

Dry phase reactor for generating medical isotopes

DOEpatents

Mackie, Thomas Rockwell; Heltemes, Thad Alexander

2016-05-03

An apparatus for generating medical isotopes provides for the irradiation of dry-phase, granular uranium compounds which are then dissolved in a solvent for separation of the medical isotope from the irradiated compound. Once the medical isotope is removed, the dissolved compound may be reconstituted in dry granular form for repeated irradiation.

Novel hybrid isotope separation scheme and apparatus

DOEpatents

Maya, Jakob

1991-01-01

A method of yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which the specific isotope is to be isolated, radiating the gas with frequencies characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photoionization reaction of the desired isotope, and collecting the specific isotope ion by suitable ion collection means.

[Baseflow separation methods in hydrological process research: a review].

PubMed

Xu, Lei-Lei; Liu, Jing-Lin; Jin, Chang-Jie; Wang, An-Zhi; Guan, De-Xin; Wu, Jia-Bing; Yuan, Feng-Hui

2011-11-01

Baseflow separation research is regarded as one of the most important and difficult issues in hydrology and ecohydrology, but lacked of unified standards in the concepts and methods. This paper introduced the theories of baseflow separation based on the definitions of baseflow components, and analyzed the development course of different baseflow separation methods. Among the methods developed, graph separation method is simple and applicable but arbitrary, balance method accords with hydrological mechanism but is difficult in application, whereas time series separation method and isotopic method can overcome the subjective and arbitrary defects caused by graph separation method, and thus can obtain the baseflow procedure quickly and efficiently. In recent years, hydrological modeling, digital filtering, and isotopic method are the main methods used for baseflow separation.

Novel hybrid isotope separation scheme and apparatus

DOEpatents

Maya, J.

1991-06-18

A method is described for yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which the specific isotope is to be isolated, radiating the gas with frequencies characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photoionization reaction of the desired isotope, and collecting the specific isotope ion by suitable ion collection means. 3 figures.

Cryogenic separation of an oxygen-argon mixture in natural air samples for the determination of isotope and molecular ratios.

PubMed

Keedakkadan, Habeeb Rahman; Abe, Osamu

2015-04-30

The separation and purification of oxygen-argon mixtures are critical in the high-precision analysis of Δ(17) O and δ(O2 /Ar) for geochemical applications. At present, chromatographic methods are used for the separation and purification of oxygen-argon mixtures or pure oxygen, but these methods require the use of high-purity helium as a carrier gas. Considerable interest has been expressed in the development of a helium-free cryogenic separation of oxygen-argon mixtures in natural air samples. The precise and simplified cryogenic separation of oxygen-argon mixtures from natural air samples presented here was made possible using a single 5A (30/60 mesh) molecular sieve column. The method involves the trapping of eluted gases using molecular sieves at liquid nitrogen temperature, which is associated with isotopic fractionation. We tested the proposed method for the determination of isotopic fractionations during the gas exchange between water and atmospheric air at equilibrium. The dependency of fractionation was studied at different water temperatures and for different methods of equilibration (bubbling and stirring). Isotopic and molecular fractionations during gas desorption from molecular sieves were studied for different amounts and types of molecular sieves. Repeated measurements of atmospheric air yielded a reproducibility (±SD) of 0.021 ‰, 0.044 ‰, 15 per meg and 1.9 ‰ for δ(17) O, δ(18) O, Δ(17) O and δ(O2 /Ar) values, respectively. We applied the method to determine equilibrium isotope fractionation during gas exchange between air and water. Consistent δ(18) O and Δ(17) O results were obtained with the latest two studies, whereas there was a significant difference in δ(18) O values between seawater and deionized water. We have revised a helium-free, cryogenic separation of oxygen-argon mixtures in natural air samples for isotopic and molecular ratio analysis. The use of a single 13X (1/8" pellet) molecular sieve yielded the smallest isotopic and molecular fractionations, and this fractionation by molecular sieves can be corrected by the amount of molecular sieve used in the experiment. The reproducibility of the method was tested by the measurement of the oxygen isotope ratios of dissolved oxygen at equilibrium with atmospheric air. We confirmed that the choice of methods for making air-equilibrated water was not related to the magnitude of isotope fractionation, whereas there was a difference between seawater and deionized water. Copyright © 2015 John Wiley & Sons, Ltd.

Isotope separation apparatus and method

DOEpatents

Feldman, Barry J.

1985-01-01

The invention relates to an improved method and apparatus for laser isotope separation by photodeflection. A molecular beam comprising at least two isotopes to be separated intersects, preferably substantially perpendicular to one broad side of the molecular beam, with a laser beam traveling in a first direction. The laser beam is reflected back through the molecular beam, preferably in a second direction essentially opposite to the first direction. Because the molecules in the beam occupy various degenerate energy levels, if the laser beam comprises chirped pulses comprising selected wavelengths, the laser beam will very efficiently excite substantially all unexcited molecules and will cause stimulated emission of substantially all excited molecules of a selected one of the isotopes in the beam which such pulses encounter. Excitation caused by first direction chirped pulses moves molecules of the isotope excited thereby in the first direction. Stimulated emission of excited molecules of the isotope is brought about by returning chirped pulses traveling in the second direction. Stimulated emission moves emitting molecules in a direction opposite to the photon emitted. Because emitted photons travel in the second direction, emitting molecules move in the first direction. Substantial molecular movement of essentially all the molecules containing the one isotope is accomplished by a large number of chirped pulse-molecule interactions. A beam corer collects the molecules in the resulting enriched divergent portions of the beam.

Isotope separation apparatus

DOEpatents

Arnush, Donald; MacKenzie, Kenneth R.; Wuerker, Ralph F.

1980-01-01

Isotope separation apparatus consisting of a plurality of cells disposed adjacent to each other in an evacuated container. A common magnetic field is established extending through all of the cells. A source of energetic electrons at one end of the container generates electrons which pass through the cells along the magnetic field lines. Each cell includes an array of collector plates arranged in parallel or in tandem within a common magnetic field. Sets of collector plates are disposed adjacent to each other in each cell. Means are provided for differentially energizing ions of a desired isotope by applying energy at the cyclotron resonant frequency of the desired isotope. As a result, the energized desired ions are preferentially collected by the collector plates.

Separation of isotopes by cyclical processes

DOEpatents

Hamrin, Jr., Charles E.; Weaver, Kenny

1976-11-02

Various isotopes of hydrogen are separated by a cyclic sorption process in which a gas stream containing the isotopes is periodically passed through a high pressure column containing a palladium sorbent. A portion of the product from the high pressure column is passed through a second column at lower pressure to act as a purge. Before the sorbent in the high pressure column becomes saturated, the sequence is reversed with the stream flowing through the former low-pressure column now at high pressure, and a portion of the product purging the former high pressure column now at low pressure. The sequence is continued in cyclic manner with the product being enriched in a particular isotope.

Method of separating boron isotopes

DOEpatents

Jensen, R.J.; Thorne, J.M.; Cluff, C.L.

1981-01-23

A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)-dichloroborane as the feed material. The photolysis can readily by achieved with CO/sub 2/ laser radiation and using fluences significantly below those required to dissociate BCl/sub 3/.

Method of separating boron isotopes

DOEpatents

Jensen, Reed J.; Thorne, James M.; Cluff, Coran L.; Hayes, John K.

1984-01-01

A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)dichloroborane as the feed material. The photolysis can readily be achieved with CO.sub.2 laser radiation and using fluences significantly below those required to dissociate BCl.sub.3.

Quantum tunneling of thermal protons through pristine graphene.

PubMed

Poltavsky, Igor; Zheng, Limin; Mortazavi, Majid; Tkatchenko, Alexandre

2018-05-28

Engineering of atomically thin membranes for hydrogen isotope separation is an actual challenge which has a broad range of applications. Recent experiments [M. Lozada-Hidalgo et al., Science 351, 68 (2016)] unambiguously demonstrate an order-of-magnitude difference in permeabilities of graphene-based membranes to protons and deuterons at ambient conditions, making such materials promising for novel separation technologies. Here we demonstrate that the permeability mechanism in such systems changes from quantum tunneling for protons to quasi-classical transport for heavier isotopes. Quantum nuclear effects exhibit large temperature and mass dependence, modifying the Arrhenius activation energy and Arrhenius prefactor for protons by more than 0.5 eV and by seven orders of magnitude correspondingly. Our findings not only shed light on the separation process for hydrogen isotope ions passing through pristine graphene but also offer new insights for controlling ion transport mechanisms in nanostructured separation membranes by manipulating the shape of the barrier and transport process conditions.

Intramolecular carbon and nitrogen isotope analysis by quantitative dry fragmentation of the phenylurea herbicide isoproturon in a combined injector/capillary reactor prior to GC separation.

PubMed

Penning, Holger; Elsner, Martin

2007-11-01

Potentially, compound-specific isotope analysis may provide unique information on source and fate of pesticides in natural systems. Yet for isotope analysis, LC-based methods that are based on the use of organic solvents often cannot be used and GC-based analysis is frequently not possible due to thermolability of the analyte. A typical example of a compound with such properties is isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea), belonging to the worldwide extensively used phenylurea herbicides. To make isoproturon accessible to carbon and nitrogen isotope analysis, we developed a GC-based method during which isoproturon was quantitatively fragmented to dimethylamine and 4-isopropylphenylisocyanate. Fragmentation occurred only partially in the injector but was mainly achieved on a heated capillary column. The fragments were then chromatographically separated and individually measured by isotope ratio mass spectrometry. The reliability of the method was tested in hydrolysis experiments with three isotopically different batches of isoproturon. For all three products, the same isotope fractionation factors were observed during conversion and the difference in isotope composition between the batches was preserved. This study demonstrates that fragmentation of phenylurea herbicides does not only make them accessible to isotope analysis but even enables determination of intramolecular isotope fractionation.

Chromatographic hydrogen isotope separation

DOEpatents

Aldridge, Frederick T.

1981-01-01

Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

Chromatographic hydrogen isotope separation

DOEpatents

Aldridge, F.T.

Intermetallic compounds with the CaCu/sub 5/ type of crystal structure, particularly LaNiCo/sub 4/ and CaNi/sub 5/, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation column. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale multi-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen cn produce large quantities of heavy water at an effective cost for use in heavy water reactors.

Exploring emotional intelligence in a Caribbean medical school.

PubMed

Sa, B; Baboolal, N; Williams, S; Ramsewak, S

2014-03-01

To explore the emotional intelligence (EI) in medical students in a Caribbean medical school and investigate its association with gender, age, year of study and ethnicity. A cross-sectional design using convenient sampling of 304 years two to five undergraduate medical students at the School of Medicine, the University of the West Indies (UWI), St Augustine campus, was conducted. The Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT-V2.0) was administered to test four branches of EI: perceiving emotions, facilitating thought, understanding emotions and managing emotions. Data were analysed using SPSS version 19. T-test, analysis of variance (ANOVA) and r (product moment correlation) were calculated to establish the effects of selected variables (gender, age, year of study and ethnicity) on total and sub-scales EI scores and tested against 0.05 and 0.01 significance levels. The total mean score for EI fell within the average according to MSCEIT standards. Gender analysis showed significantly higher scores for males and for younger age groups (< 25 years). Year of study and ethnicity did not yield any significant effect. These findings of higher EI scores in males and younger students are unusual, given the well-publicized stereotype of the Caribbean male and the perception that advancing age brings maturity and emotional stability. It would be valuable to widen this study by including other UWI campuses and offshore medical schools in the Caribbean. This preliminary study examined a sample of medical students from a well-established Caribbean medical school. Since EI is considered to be important in the assessment and training of medical undergraduates, consideration should be given to introducing interventions aimed at increasing EI.

Exploring Emotional Intelligence in a Caribbean Medical School

PubMed Central

Sa, B; Baboolal, N; Williams, S; Ramsewak, S

2014-01-01

Objective: To explore the emotional intelligence (EI) in medical students in a Caribbean medical school and investigate its association with gender, age, year of study and ethnicity. Design and Methods: A cross-sectional design using convenient sampling of 304 years two to five undergraduate medical students at the School of Medicine, The University of the West Indies (UWI), St Augustine campus, was conducted. The Mayer-Salovey-Caruso Emotional Intelligence Test (MSCEIT-V2.0) was administered to test four branches of EI: perceiving emotions, facilitating thought, understanding emotions and managing emotions. Data were analysed using SPSS version 19. T-test, analysis of variance (ANOVA) and r (product moment correlation) were calculated to establish the effects of selected variables (gender, age, year of study and ethnicity) on total and sub-scales EI scores and tested against 0.05 and 0.01 significance levels. Results: The total mean score for EI fell within the average according to MSCEIT standards. Gender analysis showed significantly higher scores for males and for younger age groups (< 25 years). Year of study and ethnicity did not yield any significant effect. Conclusions: These findings of higher EI scores in males and younger students are unusual, given the well-publicized stereotype of the Caribbean male and the perception that advancing age brings maturity and emotional stability. It would be valuable to widen this study by including other UWI campuses and offshore medical schools in the Caribbean. This preliminary study examined a sample of medical students from a well-established Caribbean medical school. Since EI is considered to be important in the assessment and training of medical undergraduates, consideration should be given to introducing interventions aimed at increasing EI. PMID:25303251

Development and Validation of a Measure of Attitudes toward Fluffy Women

PubMed Central

Barned, C; Lipps, GE

2014-01-01

ABSTRACT Background: There is an absence of research on the newly evolved term “fluffy” which describes body image and personality features among women. Research on “fluffiness” among Caribbean peoples has been limited by the lack of valid and reliable measures of the concept. Objective: This project addresses this problem by exploring the internal consistency reliability and the concurrent and discriminant validity of the Attitudes toward Fluffy Women Scale (ATFW) using a mixture of past and present students from The University of the West Indies (UWI), Mona, and the University of Technology (UTech), Kingston. Method: Past or present students from The UWI, Mona, and UTech, Kingston, were recruited for the study through the use of convenience sampling. A total of 80 students (38 males, 47.5%; 42 females, 52.5%) participated in the study. Results: Overall, the ATFW was found to have an acceptable degree of internal consistency reliability (α = 0.90). The scale also had reasonably good concurrent validity as evidenced by moderate correlations with scores on the Attitudes Toward Obese Persons Scale (r = −0.42) and acceptable discriminant validity as demonstrated through low correlations with a Bogardus Social Distance Scale designed to assess prejudice toward people living with the human immunodeficiency virus [HIV] (r = 0.29). This pattern of scores suggests that the majority of the stable variance underlying the ATFW assesses the “fluffy” concept (17.6%) while a smaller degree of the variability (8%) measures a conceptually similar but distinct concept. Conclusion: The Attitudes toward Fluffy Women scale was found to be a reliable and valid scale for assessing the attitudes of young adults toward fluffy women. PMID:25803379

Process for producing enriched uranium having a .sup.235 U content of at least 4 wt. % via combination of a gaseous diffusion process and an atomic vapor laser isotope separation process to eliminate uranium hexafluoride tails storage

DOEpatents

Horton, James A.; Hayden, Jr., Howard W.

1995-01-01

An uranium enrichment process capable of producing an enriched uranium, having a .sup.235 U content greater than about 4 wt. %, is disclosed which will consume less energy and produce metallic uranium tails having a lower .sup.235 U content than the tails normally produced in a gaseous diffusion separation process and, therefore, eliminate UF.sub.6 tails storage and sharply reduce fluorine use. The uranium enrichment process comprises feeding metallic uranium into an atomic vapor laser isotope separation process to produce an enriched metallic uranium isotopic mixture having a .sup.235 U content of at least about 2 wt. % and a metallic uranium residue containing from about 0.1 wt. % to about 0.2 wt. % .sup.235 U; fluorinating this enriched metallic uranium isotopic mixture to form UF.sub.6 ; processing the resultant isotopic mixture of UF.sub.6 in a gaseous diffusion process to produce a final enriched uranium product having a .sup.235 U content of at least 4 wt. %, and up to 93.5 wt. % or higher, of the total uranium content of the product, and a low .sup.235 U content UF.sub.6 having a .sup.235 U content of about 0.71 wt. % of the total uranium content of the low .sup.235 U content UF.sub.6 ; and converting this low .sup.235 U content UF.sub.6 to metallic uranium for recycle to the atomic vapor laser isotope separation process.

Process for producing enriched uranium having a {sup 235}U content of at least 4 wt. % via combination of a gaseous diffusion process and an atomic vapor laser isotope separation process to eliminate uranium hexafluoride tails storage

DOEpatents

Horton, J.A.; Hayden, H.W. Jr.

1995-05-30

An uranium enrichment process capable of producing an enriched uranium, having a {sup 235}U content greater than about 4 wt. %, is disclosed which will consume less energy and produce metallic uranium tails having a lower {sup 235}U content than the tails normally produced in a gaseous diffusion separation process and, therefore, eliminate UF{sub 6} tails storage and sharply reduce fluorine use. The uranium enrichment process comprises feeding metallic uranium into an atomic vapor laser isotope separation process to produce an enriched metallic uranium isotopic mixture having a {sup 235} U content of at least about 2 wt. % and a metallic uranium residue containing from about 0.1 wt. % to about 0.2 wt. % {sup 235} U; fluorinating this enriched metallic uranium isotopic mixture to form UF{sub 6}; processing the resultant isotopic mixture of UF{sub 6} in a gaseous diffusion process to produce a final enriched uranium product having a {sup 235}U content of at least 4 wt. %, and up to 93.5 wt. % or higher, of the total uranium content of the product, and a low {sup 235}U content UF{sub 6} having a {sup 235}U content of about 0.71 wt. % of the total uranium content of the low {sup 235}U content UF{sub 6}; and converting this low {sup 235}U content UF{sub 6} to metallic uranium for recycle to the atomic vapor laser isotope separation process. 4 figs.

Basic features of boron isotope separation by SILARC method in the two-step iterative static model

NASA Astrophysics Data System (ADS)

Lyakhov, K. A.; Lee, H. J.

2013-05-01

In this paper we develop a new static model for boron isotope separation by the laser assisted retardation of condensation method (SILARC) on the basis of model proposed by Jeff Eerkens. Our model is thought to be adequate to so-called two-step iterative scheme for isotope separation. This rather simple model helps to understand combined action on boron separation by SILARC method of all important parameters and relations between them. These parameters include carrier gas, molar fraction of BCl3 molecules in carrier gas, laser pulse intensity, gas pulse duration, gas pressure and temperature in reservoir and irradiation cells, optimal irradiation cell and skimmer chamber volumes, and optimal nozzle throughput. A method for finding optimal values of these parameters based on some objective function global minimum search was suggested. It turns out that minimum of this objective function is directly related to the minimum of total energy consumed, and total setup volume. Relations between nozzle throat area, IC volume, laser intensity, number of nozzles, number of vacuum pumps, and required isotope production rate were derived. Two types of industrial scale irradiation cells are compared. The first one has one large throughput slit nozzle, while the second one has numerous small nozzles arranged in parallel arrays for better overlap with laser beam. It is shown that the last one outperforms the former one significantly. It is argued that NO2 is the best carrier gas for boron isotope separation from the point of view of energy efficiency and Ar from the point of view of setup compactness.

A modified lead-matrix separation procedure shown for lead isotope analysis in Trojan silver artefacts as an example.

PubMed

Vogl, Jochen; Paz, Boaz; Koenig, Maren; Pritzkow, Wolfgang

2013-03-01

A modified Pb-matrix separation procedure using NH4HCO3 solution as eluent has been developed and validated for determination of Pb isotope amount ratios by thermal ionization mass spectrometry. The procedure is based on chromatographic separation using the Pb·Spec resin and an in-house-prepared NH4HCO3 solution serving as eluent. The advantages of this eluent are low Pb blanks (<40 pg mL(-1)) and the property that NH4HCO3 can be easily removed by use of a heating step (>60 °C). Pb recovery is >95 % for water samples. For archaeological silver samples, however, the Pb recovery is reduced to approximately 50 %, but causes no bias in the determination of Pb isotope amount ratios. The validated procedure was used to determine lead isotope amount ratios in Trojan silver artefacts with expanded uncertainties (k = 2) <0.09 %.

Future Opportunities at the Facility for Rare Isotope Beams

NASA Astrophysics Data System (ADS)

Sherrill, Bradley M.

2018-05-01

This paper overviews the Facility for Rare Isotope Beams, FRIB, its construction status at the time of the conference, and its scientific program. FRIB is based on a high-power, heavy-ion, superconducting linear accelerator that is designed to deliver at least 400kW at 200 MeV/u for all stable-ion beams and produce a large fraction of all possible isotopes of the elements. A three-stage fragment separator will separate rare isotope beams for use in experiments at high energy or stopped and reaccelerated to up to 10MeV/u. The facility is expected to have first beams in 2021. An overview of the planned scientific program, experimental capabilities, and equipment initiatives are presented.

Numerical modelling of the flow and isotope separation in centrifuge Iguasu for different lengths of the rotor

NASA Astrophysics Data System (ADS)

Bogovalov, S. V.; Borisevich, V. D.; Borman, V. D.; Tronin, I. V.; Tronin, V. N.

2016-06-01

Numerical modelling and optimization of the gas flow and isotope separation in the Iguasu gas centrifuge (GC) for uranium enrichment have been performed for different lengths of the rotor. The calculations show that the specific separative power of the GC reduces with the length of the rotor. We show that the reduction of the specific separative power is connected with the growth of the pressure in the optimal regime and corresponding growth of temperature to prevent the working gas sublimation. The specific separative power remains constant with the growth of the rotor length provided that the temperature of the gas is taken to be constant.

Numerical modelling of the flow and isotope separation in centrifuge Iguasu for different lengths of the rotor

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bogovalov, S. V.; Borisevich, V. D.; Borman, V. D.

Numerical modelling and optimization of the gas flow and isotope separation in the Iguasu gas centrifuge (GC) for uranium enrichment have been performed for different lengths of the rotor. The calculations show that the specific separative power of the GC reduces with the length of the rotor. We show that the reduction of the specific separative power is connected with the growth of the pressure in the optimal regime and corresponding growth of temperature to prevent the working gas sublimation. The specific separative power remains constant with the growth of the rotor length provided that the temperature of the gasmore » is taken to be constant.« less

Hydrogen isotope separation utilizing bulk getters

DOEpatents

Knize, R.J.; Cecchi, J.L.

1991-08-20

Tritium and deuterium are separated from a gaseous mixture thereof, derived from a nuclear fusion reactor or some other source, by providing a casing with a bulk getter therein for absorbing the gaseous mixture to produce an initial loading of the getter, partially desorbing the getter to produce a desorbed mixture which is tritium-enriched, pumping the desorbed mixture into a separate container, the remaining gaseous loading in the getter being deuterium-enriched, desorbing the getter to a substantially greater extent to produce a deuterium-enriched gaseous mixture, and removing the deuterium-enriched mixture into another container. The bulk getter may comprise a zirconium-aluminum alloy, or a zirconium-vanadium-iron alloy. The partial desorption may reduce the loading by approximately fifty percent. The basic procedure may be extended to produce a multistage isotope separator, including at least one additional bulk getter into which the tritium-enriched mixture is absorbed. The second getter is then partially desorbed to produce a desorbed mixture which is further tritium-enriched. The last-mentioned mixture is then removed from the container for the second getter, which is then desorbed to a substantially greater extent to produce a desorbed mixture which is deuterium-enriched. The last-mentioned mixture is then removed so that the cycle can be continued and repeated. The method of isotope separation is also applicable to other hydrogen isotopes, in that the method can be employed for separating either deuterium or tritium from normal hydrogen. 4 figures.

Hydrogen isotope separation utilizing bulk getters

DOEpatents

Knize, Randall J.; Cecchi, Joseph L.

1991-01-01

Tritium and deuterium are separated from a gaseous mixture thereof, derived from a nuclear fusion reactor or some other source, by providing a casing with a bulk getter therein for absorbing the gaseous mixture to produce an initial loading of the getter, partially desorbing the getter to produce a desorbed mixture which is tritium-enriched, pumping the desorbed mixture into a separate container, the remaining gaseous loading in the getter being deuterium-enriched, desorbing the getter to a substantially greater extent to produce a deuterium-enriched gaseous mixture, and removing the deuterium-enriched mixture into another container. The bulk getter may comprise a zirconium-aluminum alloy, or a zirconium-vanadium-iron alloy. The partial desorption may reduce the loading by approximately fifty percent. The basic procedure may be extended to produce a multistage isotope separator, including at least one additional bulk getter into which the tritium-enriched mixture is absorbed. The second getter is then partially desorbed to produce a desorbed mixture which is further tritium-enriched. The last-mentioned mixture is then removed from the container for the second getter, which is then desorbed to a substantially greater extent to produce a desorbed mixture which is deuterium-enriched. The last-mentioned mixture is then removed so that the cycle can be continued and repeated. The method of isotope separation is also applicable to other hydrogen isotopes, in that the method can be employed for separating either deuterium or tritium from normal hydrogen.

Hydrogen isotope separation utilizing bulk getters

DOEpatents

Knize, Randall J.; Cecchi, Joseph L.

1990-01-01

Tritium and deuterium are separated from a gaseous mixture thereof, derived from a nuclear fusion reactor or some other source, by providing a casing with a bulk getter therein for absorbing the gaseous mixture to produce an initial loading of the getter, partially desorbing the getter to produce a desorbed mixture which is tritium-enriched, pumping the desorbed mixture into a separate container, the remaining gaseous loading in the getter being deuterium-enriched, desorbing the getter to a substantially greater extent to produce a deuterium-enriched gaseous mixture, and removing the deuterium-enriched mixture into another container. The bulk getter may comprise a zirconium-aluminum alloy, or a zirconium-vanadium-iron alloy. The partial desorption may reduce the loading by approximately fifty percent. The basic procedure may be extended to produce a multistage isotope separator, including at least one additional bulk getter into which the tritium-enriched mixture is absorbed. The second getter is then partially desorbed to produce a desorbed mixture which is further tritium-enriched. The last-mentioned mixture is then removed from the container for the second getter, which is then desorbed to a substantially greater extent to produce a desorbed mixture which is deuterium-enriched. The last-mentioned mixture is then removed so that the cycle can be continued and repeated. The method of isotope separation is also applicable to other hydrogen isotopes, in that the method can be employed for separating either deuterium or tritium from normal hydrogen.

Laser isotope separation by multiple photon absorption

DOEpatents

Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

1987-01-01

Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

Laser isotope separation by multiple photon absorption

DOEpatents

Robinson, C. Paul; Rockwood, Stephen D.; Jensen, Reed J.; Lyman, John L.; Aldridge, III, Jack P.

1977-01-01

Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, in the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO.sub.2 laser light may be used to highly enrich .sup.34 S in natural SF.sub.6 and .sup.11 B in natural BCl.sub.3.

Copper and Zinc isotope composition of CR, CB and CH-like meteorites.

NASA Astrophysics Data System (ADS)

Russell, S.; Zhu, X.; Guo, Y.; Mullane, E.; Gounelle, M.; Mason, T.; Coles, B.

2003-04-01

Copper and zinc isotopes have recently been shown to be variable in isotopic composi-tion among terrestrial and extraterrestrial materials [1-3]. For this study, we have se-lected samples (bulk meteorite and chondrule separates) from the CR meteorite clan: Bencubbin (CB), Renazzo (CR2), NWA 801 (CR2), and HaH237 (CH-like). These meteorites were selected because meteorites from this clan have experienced very little alteration since their initial formation [4] and for their extremely high refrac-tory/volatile element ratios. The latter characteristic may allow a test of the correlation observed by [2] between element ratios and Cu isotope composition. Measurements were performed on NHM/IC Micromass Isoprobe and Oxford Nu MC-ICP-MS using techniques described elsewhere [1,5]. Each of the meteorites measured so far for Cu and Zn are isotopically light compared to the terrestrial mantle. This suggests that the terrestrial value may have been altered from the pristine solar system value, or else there were multiple early solar system components. Zinc isotopic com-positions lie on a fractionation line and range from δ66ZnNIST = -1.4±0.1ppm (bulk NWA801) to -1.9±0.1ppm (separated chondrule, NWA 801). Copper isotope compositions vary from δ65CuNIST976 = -1.5±0.1ppm (bulk Renazzo) to -3.1±0.1ppm (separated chondrule, NWA 801). Two chondrules from NWA 801 have differing Cu isotope values (-3.1±0.1 and -2.0±0.1ppm) and both are lighter than the bulk meteorite (-1.9±0.1ppm), suggesting a lack of equilibration with respect to Cu in this meteorite. The light values for the two separated chondrules, compared the bulk meteorite, hints that chondrules may be isotopically lighter than co-existing matrix, metal and sulphides with respect to Cu. The copper isotope compositions are not as isotopically light as expected for the high refractory/volatile element ratio observed in these chondrites. Thus a model to account for the Cu isotopes in chondrites may require greater com-plexity than one involving simple mixing of two primordial components. References: [1] Zhu et al., Chem. Geol. 163,139-149 (2000). [2] Luck et al., GCA 67 143 (2002). [3] Luck et al., MAPS 35 A100 (2000) [4] Krot et al., MAPS 37 1451-1490 (2002) [5] Mason et al. EOS Trans. AGU abstract V21A-0966 82 (2001)

Development of an on-line flow injection Sr/matrix separation method for accurate, high-throughput determination of Sr isotope ratios by multiple collector-inductively coupled plasma-mass spectrometry.

PubMed

Galler, Patrick; Limbeck, Andreas; Boulyga, Sergei F; Stingeder, Gerhard; Hirata, Takafumi; Prohaska, Thomas

2007-07-01

This work introduces a newly developed on-line flow injection (FI) Sr/Rb separation method as an alternative to the common, manual Sr/matrix batch separation procedure, since total analysis time is often limited by sample preparation despite the fast rate of data acquisition possible by inductively coupled plasma-mass spectrometers (ICPMS). Separation columns containing approximately 100 muL of Sr-specific resin were used for on-line FI Sr/matrix separation with subsequent determination of (87)Sr/(86)Sr isotope ratios by multiple collector ICPMS. The occurrence of memory effects exhibited by the Sr-specific resin, a major restriction to the repetitive use of this costly material, could successfully be overcome. The method was fully validated by means of certified reference materials. A set of two biological and six geological Sr- and Rb-bearing samples was successfully characterized for its (87)Sr/(86)Sr isotope ratios with precisions of 0.01-0.04% 2 RSD (n = 5-10). Based on our measurements we suggest (87)Sr/(86)Sr isotope ratios of 0.713 15 +/- 0.000 16 (2 SD) and 0.709 31 +/- 0.000 06 (2 SD) for the NIST SRM 1400 bone ash and the NIST SRM 1486 bone meal, respectively. Measured (87)Sr/(86)Sr isotope ratios for five basalt samples are in excellent agreement with published data with deviations from the published value ranging from 0 to 0.03%. A mica sample with a Rb/Sr ratio of approximately 1 was successfully characterized for its (87)Sr/(86)Sr isotope signature to be 0.718 24 +/- 0.000 29 (2 SD) by the proposed method. Synthetic samples with Rb/Sr ratios of up to 10/1 could successfully be measured without significant interferences on mass 87, which would otherwise bias the accuracy and uncertainty of the obtained data.

Interactions between surface waters in King George Island, Antarctica - a stable isotope perspective

NASA Astrophysics Data System (ADS)

Perşoiu, Aurel; Bădăluşă, Carmen

2017-04-01

In this paper we present a first study of the isotopic composition of surface waters in the southern peninsulas (Barton, Fildes, Weaver and Potter) of King George Island, Antarctica. We have collected > 200 samples of snow and snowmelt, water (lake, river and spring), ice (glacier ice and permafrost) from the four peninsulas in February 2016 and analyzed them for their oxygen and hydrogen stable isotopic composition. Samples from lake water (50+) indicate a clear west-east depletion trend, suggesting a rain-out process as air masses are moving westward (and are progressively depleted in heavy isotopes) from their origin in the Drake Passage. In both Fildes and Barton Peninsulas, permafrost samples have the heaviest isotopic composition, most probably due to preferential incorporation of heavy isotopes in the ice during freezing (and no fractionation during melting). As permafrost melts, the resulting water mixes with isotopically lighter infiltrated snowmelt, and thus the groundwater has a lower isotopic composition. Further, lake and river (the later fed by lakes) water has the lightest isotopic composition, being derived mostly from the melting of light snow and glacier ice. It seems feasible to separate isotopically water in lakes/rivers (largely fed by melting multi-year glaciers and snow) and water from melting of snow/ground ice This preliminary study suggests that it is possible to separate various water sources in the southern peninsulas of King George Island, and this separation could be used to study permafrost degradation, as well as feeding and migration patterns in the bird fauna, with implications for protection purposes. Acknowledgments. The National Institute of Research and Development for Biological Sciences (Bucharest, Romania) and the Korean polar institute financially supported fieldwork in King George Island. We thank the personal at King Sejong (South Korea), Belingshaussen (Russia) and Carlini (Argentina) stations in King George Island for logistic supports.

RECTIFIED ABSORPTION METHOD FOR THE SEPARATION OF HYDROGEN ISOTOPES

DOEpatents

Hunt, C.D.; Hanson, D.N.

1961-10-17

A method is described for separating and recovering heavy hydrogen isotopes from gaseous mixtures by multiple stage cyclic absorption and rectification from an approximate solvent. In particular, it is useful for recovering such isoteoes from ammonia feedstock streams containing nitrogen solvent. Modifications of the process ranging from isobaric to isothermal are provided. Certain impurities are tolerated, giving advantages over conventional fractional distillation processes. (AEC)

New design studies for TRIUMF's ARIEL High Resolution Separator

NASA Astrophysics Data System (ADS)

Maloney, J. A.; Baartman, R.; Marchetto, M.

2016-06-01

As part of its new Advanced Rare IsotopE Laboratory (ARIEL), TRIUMF is designing a novel High Resolution Separator (HRS) (Maloney et al., 2015) to separate rare isotopes. The HRS has a 180° bend, separated into two 90° magnetic dipoles, bend radius 1.2 m, with an electrostatic multipole corrector between them. Second order correction comes mainly from the dipole edge curvatures, but is intended to be fine-tuned with a sextupole component and a small octupole component in the multipole. This combination is designed to achieve 1:20,000 resolution for a 3 μm (horizontal) and 6 μm (vertical) emittance. A design for the HRS dipole magnets achieves both radial and integral flatness goals of <10-5. A review of the optical design for the HRS is presented, including the study of limiting factors affecting separation, matching and aberration correction. Field simulations from the OPERA-3D (OPERA) [2] models of the dipole magnets are used in COSY Infinity (COSY) (Berz and Makino, 2005) [3] to find and optimize the transfer maps to 3rd order and study residual nonlinearities to 8th order.

Laser-assisted isotope separation of tritium

DOEpatents

Herman, Irving P.; Marling, Jack B.

1983-01-01

Methods for laser-assisted isotope separation of tritium, using infrared multiple photon dissociation of tritium-bearing products in the gas phase. One such process involves the steps of (1) catalytic exchange of a deuterium-bearing molecule XYD with tritiated water DTO from sources such as a heavy water fission reactor, to produce the tritium-bearing working molecules XYT and (2) photoselective dissociation of XYT to form a tritium-rich product. By an analogous procedure, tritium is separated from tritium-bearing materials that contain predominately hydrogen such as a light water coolant from fission or fusion reactors.

ISOTOPE CONVERSION DEVICE

DOEpatents

Wigner, E.P.; Young, G.J.; Ohlinger, L.A.

1957-12-01

This patent relates to nuclear reactors of tbe type utilizing a liquid fuel and designed to convert a non-thermally fissionable isotope to a thermally fissionable isotope by neutron absorption. A tank containing a reactive composition of a thermally fissionable isotope dispersed in a liquid moderator is disposed within an outer tank containing a slurry of a non-thermally fissionable isotope convertible to a thermally fissionable isotope by neutron absorption. A control rod is used to control the chain reaction in the reactive composition and means are provided for circulating and cooling the reactive composition and slurry in separate circuits.

La–Ce isotope measurements by multicollector-ICPMS† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c7ja00256d

PubMed Central

Münker, Carsten; Strub, Erik

2017-01-01

The 138La–138Ce decay system (half-life 1.02 × 1011 years) is a potentially highly useful tool to unravel information about the timing of geological processes and about the interaction of geological reservoirs on earth, complementing information from the more popular 147Sm–143Nd and 176Lu–176Hf isotope systems. Previously published analytical protocols were limited to TIMS. Here we present for the first time an analytical protocol that employs MC-ICPMS, with an improved precision and sensitivity. To perform sufficiently accurate La–Ce measurements, an efficient ion-chromatographic procedure is required to separate Ce from the other rare earth elements (REE) and Ba quantitatively. This study presents an improved ion-chromatographic procedure that separates La and Ce from rock samples using a three-step column separation. After REE separation by cation exchange, Ce is separated employing an Ln Spec column and selective oxidation. In the last step, a cation clean-up chemistry is performed to remove all remaining interferences. Our MC-ICPMS measurement protocol includes all stable Ce isotopes (136Ce, 138Ce, 140Ce and 142Ce), by employing a 1010 ohm amplifier for the most abundant isotope 140Ce. An external reproducibility of ±0.25ε-units (2 r.s.d) has been routinely achieved for 138Ce measurements for as little as 150–600 ng Ce, depending on the sample–skimmer cone combinations being used. Because the traditionally used JMC-304 Ce reference material is not commercially available anymore, a new reference material was prepared from AMES laboratory Ce metal (Cologne-AMES). In order to compare the new material with the previously reported isotopic composition of AMES material prepared at Mainz (Mainz-AMES), Cologne-AMES and JMC-304 were measured relative to each other in the same analytical session, demonstrating isotope heterogeneity between the two AMES and different JMC-304 batches used in the literature. To enable sufficiently precise age correction of radiogenic 138Ce and to perform isochron dating, a protocol was developed where La and Ce concentrations are determined by isotope dilution (ID), using an isotope tracer enriched in 138La and 142Ce. The new protocols were applied to determine the variations of Ce isotope compositions and La–Ce concentrations of certified geochemical reference materials (CRMs): BCR-2, BCR-1, BHVO-2, JR-1, JA-2, JB-3, JG-1, JR-1, JB-1b, AGV-1 and one in-house La Palma standard. PMID:29456283

New Fragment Separation Technology for Superheavy Element Research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shaughnessy, D A; Moody, K J; Henderson, R A

2008-01-28

This project consisted of three major research areas: (1) development of a solid Pu ceramic target for the MASHA separator, (2) chemical separation of nuclear decay products, and (3) production of new isotopes and elements through nuclear reactions. There have been 16 publications as a result of this project, and this collection of papers summarizes our accomplishments in each of the three areas of research listed above. The MASHA (Mass Analyzer for Super-Heavy Atoms) separator is being constructed at the U400 Cyclotron at the Flerov Laboratory of Nuclear Reactions in Dubna, Russia. The purpose of the separator is to physicallymore » separate the products from nuclear reactions based on their isotopic masses rather than their decay characteristics. The separator was designed to have a separation between isotopic masses of {+-}0.25 amu, which would enable the mass of element 114 isotopes to be measured with outstanding resolution, thereby confirming their discovery. In order to increase the production rate of element 114 nuclides produced via the {sup 244}Pu+{sup 48}Ca reaction, a new target technology was required. Instead of a traditional thin actinide target, the MASHA separator required a thick, ceramic-based Pu target that was thick enough to increase element 114 production while still being porous enough to allow reaction products to migrate out of the target and travel through the separator to the detector array located at the back end. In collaboration with UNLV, we began work on development of the Pu target for MASHA. Using waste-form synthesis technology, we began by creating zirconia-based matrices that would form a ceramic with plutonium oxide. We used samarium oxide as a surrogate for Pu and created ceramics that had varying amounts of the starting materials in order to establish trends in material density and porosity. The results from this work are described in more detail in Refs. [1,4,10]. Unfortunately, work on MASHA was delayed in Russia because it was found that the efficiency of transporting products from the target chamber to the detector array was much too low for applications in heavy element experiments where production rates are on the order of one atom per day or less. Work continues on the MASHA separator, and once the efficiency has been improved, we plan to continue our work on the Pu target for future element 114 experiments. Due to the delays of the MASHA separator, work on establishing the identity of heavy element species produced through nuclear reactions focused instead on chemical separations. In particular, element 115 decays through a series of alpha decays, terminating with an element 105 isotope with a long half-life ({approx} 1 day). By chemically separating the element 105 daughter and observing its subsequent fission decay, the identity of the original parent nucleus can be established through the genetic correlation of the initial series of alpha decays. Chemical separations of element 105 were developed in Switzerland, Russia, and at LLNL. Over the course of two experiments, reaction products from the {sup 243}Am+{sup 48}Ca reaction were collected in a copper block and subsequently processed for chemical separation of the Group Five elements [8,9,13,15]. The Group Five elements were initially separated from the Group Four species, and then the samples were sub-divided into tantalum and niobium fractions. All of the fission events were observed in the tantalum fractions, which implied that element 105 behaved more like tantalum under the chemical conditions of these experiments. These experiments were very successful, and not only demonstrated that chemical separation could be performed on single atoms of interest, but also lent proof to the identity of the parent nucleus as element 115. Subsequent analysis of the alpha spectra taken during the experiment further prove that the fission events observed during the two experiments came from element 105 as the decay daughter of element 115 and could not attributed to interference from other background species [16]. The final aspect of this project was the production of new isotopes and elements. All of the experiments were performed in Dubna at the U400 Cyclotron and the results are described in more detail in Refs. [2,3,5-8,11,12,14]. The first experiments were designed to establish the decay properties of isotopes of elements 112, 114, and 116 [5]. Because these isotopic signatures were established through these initial experiments, the discovery of element 118 [11] was possible, since the 118 nuclides decayed into these previously studied isotopes. This was the first successful report of the discovery of element 118, which was reported by the media to a large extent. The last experiment that was performed for this project was the production and detection of a new isotope of element 113 [14].« less

Stormflow-hydrograph separation based on isotopes: the thrill is gone--what's next?

USGS Publications Warehouse

Burns, Douglas A.

2002-01-01

Beginning in the 1970s, the promise of a new method for separatingstormflow hydrographs using18O,2H, and3Hprovedanirresistibletemptation, and was a vast improvement over graphical separationand solute tracer methods that were prevalent at the time. Eventu-ally, hydrologists realized that this new method entailed a plethoraof assumptions about temporal and spatial homogeneity of isotopiccomposition (many of which were commonly violated). Nevertheless,hydrologists forged ahead with dozens of isotope-based hydrograph-separation studies that were published in the 1970s and 1980s.Hortonian overland flow was presumed dead. By the late 1980s,the new isotope-based hydrograph separation technique had movedinto adolescence, accompanied by typical adolescent problems suchas confusion and a search for identity. As experienced hydrologistscontinued to use the isotope technique to study stormflow hydrol-ogy in forested catchments in humid climates, their younger peersfollowed obligingly—again and again. Was Hortonian overland flowreally dead and forgotten, though? What about catchments in whichpeople live and work? And what about catchments in dry climatesand the tropics? How useful were study results when several of theassumptions about the homogeneity of source waters were commonlyviolated? What if two components could not explain the variation ofisotopic composition measured in the stream during stormflow? Andwhat about uncertainty? As with many new tools, once the initialshine wore off, the limitations of the method became a concern—oneof which was that isotope-based hydrograph separations alone couldnot reveal much about the flow paths by which water arrives at astream channel during storms.

Aspects regarding at 13C isotope separation column control using Petri nets system

NASA Astrophysics Data System (ADS)

Boca, M. L.; Ciortea, M. E.

2015-11-01

This paper is intended to show that Petri nets can be also applicable in the chemical industry. It used linear programming, modeling underlying Petri nets, especially discrete event systems for isotopic separation, the purpose of considering and control events in real-time through graphical representations. In this paper it is simulate the control of 13C Isotope Separation column using Petri nets. The major problem with 13C comes from the difficulty of obtaining it and raising its natural fraction. Carbon isotopes can be obtained using many methods, one of them being the cryogenic distillation of carbon monoxide. Some few aspects regarding operating conditions and the construction of such cryogenic plants are known today, and even less information are available as far as the separation process modeling and control are concerned. In fact, the efficient control of the carbon monoxide distillation process represents a necessity for large-scale 13C production. Referring to a classic distillation process, some models for carbon isotope separation have been proposed, some based on mass, component and energy balance equations, some on the nonlinear wave theory or the Cohen equations. For modeling the system it was used Petri nets because in this case it is deal with discrete event systems. In use of the non-timed and with auxiliary times Petri model, the transport stream was divided into sections and these sections will be analyzed successively. Because of the complexity of the system and the large amount of calculations required it was not possible to analyze the system as a unitary whole. A first attempt to model the system as a unitary whole led to the blocking of the model during simulation, because of the large processing times.

Analysis and simulation of industrial distillation processes using a graphical system design model

NASA Astrophysics Data System (ADS)

Boca, Maria Loredana; Dobra, Remus; Dragos, Pasculescu; Ahmad, Mohammad Ayaz

2016-12-01

The separation column used for experimentations one model can be configured in two ways: one - two columns of different diameters placed one within the other extension, and second way, one column with set diameter [1], [2]. The column separates the carbon isotopes based on the cryogenic distillation of pure carbon monoxide, which is fed at a constant flow rate as a gas through the feeding system [1],[2]. Based on numerical control systems used in virtual instrumentation was done some simulations of the distillation process in order to obtain of the isotope 13C at high concentrations. The experimental installation for cryogenic separation can be configured from the point of view of the separation column in two ways: Cascade - two columns of different diameters and placed one in the extension of the other column, and second one column with a set diameter. It is proposed that this installation is controlled to achieve data using a data acquisition tool and professional software that will process information from the isotopic column based on a logical dedicated algorithm. Classical isotopic column will be controlled automatically, and information about the main parameters will be monitored and properly display using one program. Take in consideration the very-low operating temperature, an efficient thermal isolation vacuum jacket is necessary. Since the "elementary separation ratio" [2] is very close to unity in order to raise the (13C) isotope concentration up to a desired level, a permanent counter current of the liquid-gaseous phases of the carbon monoxide is created by the main elements of the equipment: the boiler in the bottom-side of the column and the condenser in the top-side.

The current status of the MASHA setup

NASA Astrophysics Data System (ADS)

Vedeneev, V. Yu.; Rodin, A. M.; Krupa, L.; Belozerov, A. V.; Chernysheva, E. V.; Dmitriev, S. N.; Gulyaev, A. V.; Gulyaeva, A. V.; Kamas, D.; Kliman, J.; Komarov, A. B.; Motycak, S.; Novoselov, A. S.; Salamatin, V. S.; Stepantsov, S. V.; Podshibyakin, A. V.; Yukhimchuk, S. A.; Granja, C.; Pospisil, S.

2017-11-01

The MASHA setup designed as the mass-separator with the resolving power of about 1700, which allows mass identification of superheavy nuclides is described. The setup uses solid ISOL (Isotope Separation On-Line) method. In the present article the upgrade of some parts of MASHA are described: target box (rotating target + hot catcher), ion source based on electron cyclotron resonance, data acquisition, beam diagnostics and control systems. The upgrade is undertaken in order to increase the total separation efficiency, reduce the separation time, of the installation and working stability and make possible continuous measurements at high beam currents. Ion source efficiency was measured in autonomous regime with using calibrated gas leaks of Kr and Xe injected directly to ion source. Some results of the first experiments for production of radon isotopes using the multi-nucleon transfer reaction 48Ca+242Pu are described in the present article. The using of TIMEPIX detector with MASHA setup for neutron-rich Rn isotopes identification is also described.

Hydrogen isotope systematics of phase separation in submarine hydrothermal systems: Experimental calibration and theoretical models

USGS Publications Warehouse

Berndt, M.E.; Seal, R.R.; Shanks, Wayne C.; Seyfried, W.E.

1996-01-01

Hydrogen isotope fractionation factors were measured for coexisting brines and vapors formed by phase separation of NaCl/H2O fluids at temperatures ranging from 399-450??C and pressures from 277-397 bars. It was found that brines are depleted in D compared to coexisting vapors at all conditions studied. The magnitude of hydrogen isotope fractionation is dependent on the relative amounts of Cl in the two phases and can be empirically correlated to pressure using the following relationship: 1000 ln ??(vap-brine) = 2.54(??0.83) + 2.87(??0.69) x log (??P), where ??(vap-brine) is the fractionation factor and ??P is a pressure term representing distance from the critical curve in the NaCl/H2O system. The effect of phase separation on hydrogen isotope distribution in subseafloor hydrothermal systems depends on a number of factors, including whether phase separation is induced by heating at depth or by decompression of hydrothermal fluids ascending to the seafloor. Phase separation in most subseafloor systems appears to be a simple process driven by heating of seawater to conditions within the two-phase region, followed by segregation and entrainment of brine or vapor into a seawater dominated system. Resulting vent fluids exhibit large ranges in Cl concentration with no measurable effect on ??D. Possible exceptions to this include hydrothermal fluids venting at Axial and 9??N on the East Pacific Rise. High ??D values of low Cl fluids venting at Axial are consistent with phase separation taking place at relatively shallow levels in the oceanic crust while negative ??D values in some low Cl fluids venting at 9??N suggest involvement of a magmatic fluid component or phase separation of D-depleted brines derived during previous hydrothermal activity.

Uranium isotope separation from 1941 to the present

NASA Astrophysics Data System (ADS)

Maier-Komor, Peter

2010-02-01

Uranium isotope separation was the key development for the preparation of highly enriched isotopes in general and thus became the seed for target development and preparation for nuclear and applied physics. In 1941 (year of birth of the author) large-scale development for uranium isotope separation was started after the US authorities were warned that NAZI Germany had started its program for enrichment of uranium and might have confiscated all uranium and uranium mines in their sphere of influence. Within the framework of the Manhattan Projects the first electromagnetic mass separators (Calutrons) were installed and further developed for high throughput. The military aim of the Navy Department was to develop nuclear propulsion for submarines with practically unlimited range. Parallel to this the army worked on the development of the atomic bomb. Also in 1941 plutonium was discovered and the production of 239Pu was included into the atomic bomb program. 235U enrichment starting with natural uranium was performed in two steps with different techniques of mass separation in Oak Ridge. The first step was gas diffusion which was limited to low enrichment. The second step for high enrichment was performed with electromagnetic mass spectrometers (Calutrons). The theory for the much more effective enrichment with centrifugal separation was developed also during the Second World War, but technical problems e.g. development of high speed ball and needle bearings could not be solved before the end of the war. Spying accelerated the development of uranium separation in the Soviet Union, but also later in China, India, Pakistan, Iran and Iraq. In this paper, the physical and chemical procedures are outlined which lead to the success of the project. Some security aspects and Non-Proliferation measures are discussed.

High‐precision determination of lithium and magnesium isotopes utilising single column separation and multi‐collector inductively coupled plasma mass spectrometry

PubMed Central

Misra, Sambuddha; Lloyd, Nicholas; Elderfield, Henry; Bickle, Mike J.

2017-01-01

Rationale Li and Mg isotopes are increasingly used as a combined tool within the geosciences. However, established methods require separate sample purification protocols utilising several column separation procedures. This study presents a single‐step cation‐exchange method for quantitative separation of trace levels of Li and Mg from multiple sample matrices. Methods The column method utilises the macro‐porous AGMP‐50 resin and a high‐aspect ratio column, allowing quantitative separation of Li and Mg from natural waters, sediments, rocks and carbonate matrices following the same elution protocol. High‐precision isotope determination was conducted by multi‐collector inductively coupled plasma mass spectrometry (MC‐ICPMS) on the Thermo Scientific™ NEPTUNE Plus™ fitted with 1013 Ω amplifiers which allow accurate and precise measurements at ion beams ≤0.51 V. Results Sub‐nanogram Li samples (0.3–0.5 ng) were regularly separated (yielding Mg masses of 1–70 μg) using the presented column method. The total sample consumption during isotopic analysis is <0.5 ng Li and <115 ng Mg with long‐term external 2σ precisions of ±0.39‰ for δ7Li and ±0.07‰ for δ26Mg. The results for geological reference standards and seawater analysed by our method are in excellent agreement with published values despite the order of magnitude lower sample consumption. Conclusions The possibility of eluting small sample masses and the low analytical sample consumption make this method ideal for samples of limited mass or low Li concentration, such as foraminifera, mineral separates or dilute river waters. PMID:29078008

Isotope ratio mass spectrometry coupled to liquid and gas chromatography for wine ethanol characterization.

PubMed

Cabañero, Ana I; Recio, Jose L; Rupérez, Mercedes

2008-10-01

Two new procedures for wine ethanol 13C/12C isotope ratio determination, using high-performance liquid chromatography and gas chromatography isotope ratio mass spectrometry (HPLC/IRMS and GC/IRMS), have been developed to improve isotopic methods dedicated to the study of wine authenticity. Parameters influencing separation of ethanol from wine matrix such as column, temperature, mobile phase, flow rates and injection mode were investigated. Twenty-three wine samples from various origins were analyzed for validation of the procedures. The analytical precision was better than 0.15 per thousand, and no significant isotopic fractionation was observed employing both separative techniques coupled to IRMS. No significant differences and a very strong correlation (r = 0.99) were observed between the 13C/12C ratios obtained by the official method (elemental analyzer/isotope ratio mass spectrometry) and the proposed new methodology. The potential advantages of the developed methods over the traditional one are speed (reducing time required from hours to minutes) and simplicity. In addition, these are the first isotopic methods that allow 13C/12C determination directly from a liquid sample with no previous ethanol isolation, overcoming technical difficulties associated with sample treatment.

Hybrid isotope separation scheme

DOEpatents

Maya, Jakob

1991-01-01

A method of yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which a scavenger, radiating the gas with a wave length or frequency characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photochemical reaction between the scavenger, and collecting the specific isotope-containing chemical by using a recombination surface or by a scooping apparatus.

Separation of uranium isotopes by chemical exchange

DOEpatents

Ogle, P.R. Jr.

1974-02-26

A chemical exchange method is provided for separating /sup 235/U from / sup 238/U comprising contacting a first phase containing UF/sub 6/ with a second phase containing a compound selected from the group consisting of NOUF/sub 6/, NOUF/sub 7/, and NO/sub 2/UF/sub 7/ until the U Fsub 6/ in the first phase becomes enriched in the /sup 235/U isotope. (Official Gazette)

Laser isotope separation by multiple photon absorption

DOEpatents

Robinson, C.P.; Rockwood, S.D.; Jensen, R.J.; Lyman, J.L.; Aldridge, J.P. III.

1987-04-07

Multiple photon absorption from an intense beam of infrared laser light may be used to induce selective chemical reactions in molecular species which result in isotope separation or enrichment. The molecular species must have a sufficient density of vibrational states in its vibrational manifold that, is the presence of sufficiently intense infrared laser light tuned to selectively excite only those molecules containing a particular isotope, multiple photon absorption can occur. By this technique, for example, intense CO[sub 2] laser light may be used to highly enrich [sup 34]S in natural SF[sub 6] and [sup 11]B in natural BCl[sub 3]. 8 figs.

Isotope separation by selective photodissociation of glyoxal

DOEpatents

Marling, John B.

1976-01-01

Dissociation products, mainly formaldehyde and carbon monoxide, enriched in a desired isotope of carbon, oxygen, or hydrogen are obtained by the selective photodissociation of glyoxal wherein glyoxal is subjected to electromagnetic radiation of a predetermined wavelength such that photon absorption excites and induces dissociation of only those molecules of glyoxal containing the desired isotope.

Isotope ratio analysis of individual sub-micrometer plutonium particles with inductively coupled plasma mass spectrometry.

PubMed

Esaka, Fumitaka; Magara, Masaaki; Suzuki, Daisuke; Miyamoto, Yutaka; Lee, Chi-Gyu; Kimura, Takaumi

2010-12-15

Information on plutonium isotope ratios in individual particles is of great importance for nuclear safeguards, nuclear forensics and so on. Although secondary ion mass spectrometry (SIMS) is successfully utilized for the analysis of individual uranium particles, the isobaric interference of americium-241 to plutonium-241 makes difficult to obtain accurate isotope ratios in individual plutonium particles. In the present work, an analytical technique by a combination of chemical separation and inductively coupled plasma mass spectrometry (ICP-MS) is developed and applied to isotope ratio analysis of individual sub-micrometer plutonium particles. The ICP-MS results for individual plutonium particles prepared from a standard reference material (NBL SRM-947) indicate that the use of a desolvation system for sample introduction improves the precision of isotope ratios. In addition, the accuracy of the (241)Pu/(239)Pu isotope ratio is much improved, owing to the chemical separation of plutonium and americium. In conclusion, the performance of the proposed ICP-MS technique is sufficient for the analysis of individual plutonium particles. Copyright © 2010 Elsevier B.V. All rights reserved.

Hydrogen isotope separation using molecular sieve of synthetic zeolite 3A

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kotoh, K.; Kimura, K.; Nakamura, Y.

2008-07-15

It is known that hydrogen isotope molecules can be adsorbed easily onto synthetic zeolite 4A, 5A, and 13X at the liquid-nitrogen temperature of 77.4 K. We show here that hydrogen and deuterium are not adsorptive onto zeolite 3A at the same temperature. This phenomenon is explained by assuming the molecular sieve function in zeolite-3A-crystalline lattice structure. From a series of pseudo-isobaric experiments, it is also shown that the sieving phenomenon appears in a range above 77.4 K. This behavior is interpreted as resulting on the dependence of sieve's mesh size on temperature, where the sieving effect is considered to appearmore » at a certain temperature. In this interpretation, an isotopic difference between hydrogen and deuterium is suggested to exist in the sieving effect appearance temperatures. This is endorsed in the result of pseudo-isobaric experiments. This temperature deference is very significant because that indicates the possibility of an effective method of hydrogen isotope separation. This possibility is verified through an experimental series of adsorption-desorption with a mixture of H{sub 2} and D{sub 2}, where the gas samples adsorbed through the sieve operated at intentionally selected temperatures are isolated and then analyzed. The result demonstrates remarkable values of isotope separation factor. (authors)« less

A novel procedure for Rubidium separation and its isotope measurements on geological samples by MC-ICP-MS

NASA Astrophysics Data System (ADS)

Ma, J.; Zhang, Z.; Wei, G.; Zhang, L.

2017-12-01

A method including a novel column Rb separation procedure and high-precision Rb isotope measurement in geological materials by using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in standard-sample-bracketing (SSB) mode has been developed. Sr-Spec resin was employed, in which the distribution coefficients for Rb, K, Ba and Sr are different in nitric acid, to sequentially separate them from the matrix. The dissolved samples were loaded on the column in 3 M HNO3, the main matrix such as Al, Ca, Fe, Mg, Mn and Na were removed by rinsing with 4.5 mL HNO3, Rb and K were then sequentially eluted by 3 M HNO3 in different volumes. After that, Ba was eluted by 8 M HNO3, and Sr was finally eluted by Milli-Q water. This enable us to collect the pure Rb, K, Ba and Sr one by one with recovery close to 100% for their isotopic compositions measurement on MC-ICP-MS. We here focus on Rb isotope measurement. The measurement using MC-ICP-MS yielded an internal precision for δ87Rb of < ± 0.03‰ (2SE), and the external precision was generally better than ± 0.06‰ (2SD) based on the long-term results of the Rb standard solutions NIST SRM 984. A series of geological rock standards, were analyzed using this method, and the results indicate significant Rb isotope differences in different geologic materials. This will provide a powerful tool to investigate Rb isotope fractionation during geological processes.Based on this method, Rb isotope compositions from a basaltic weathering profile were carried out. The data show the lighter Rb (85Rb) isotope is preferentially leached from the weathering profile and remains heavy Rb isotope (87Rb) in the weathered residues during the incipient weathering stage. From the moderate to advanced weathering stage, the significant variations of Rb isotope were observed and multiple factors, such as leaching, adsorption, desorption, and precipitation, should play important role in fractionating Rb isotope.

Isotopic Evidence of Unaccounted for Fe and Cu Erythropoietic Pathways

NASA Astrophysics Data System (ADS)

Albarede, F.; Telouk, P.; Lamboux, A.; Jaouen, K.; Balter, V.

2011-12-01

Despite its potential importance for understanding perturbations in the Fe-Cu homeostatic pathways, the natural isotopic variability of these metals in the human body remains unexplored. We measured the Fe, Cu, and Zn isotope compositions of total blood, serum, and red blood cells of ~50 young blood donors by multiple-collector ICP-MS after separation and purification by anion exchange chromatography. Zn is on average 0.2 permil heavier in erythrocytes (δ 66Zn=0.44±0.33 permil) with respect to serum but shows much less overall isotopic variability than Fe and Cu, which indicates that isotope fractionation depends more on redox conditions than on ligand coordination. On average, Fe in erythrocytes (δ 56Fe=-2.59±0.47 permil) is isotopically light by 1-2 permil with respect to serum, whereas Cu in erythrocytes (δ 65Cu=0.56±0.50 permil) is 0.8 percent heavier. Fe and Cu isotope compositions clearly separate erythrocytes of men and women. Fe and Cu from B-type men erythrocytes are visibly more fractionated than all the other blood types. Isotope compositions provide an original method for evaluating metal mass balance and homeostasis. Natural isotope variability shows that the current models of Fe and Cu erythropoiesis, which assume that erythropoiesis is restricted to bone marrow, violate mass balance requirements. It unveils unsuspected major pathways for Fe, with erythropoietic production of isotopically heavy ferritin and hemosiderin, and for Cu, with isotopically light Cu being largely channeled into blood and lymphatic circulation rather than into superoxide dismutase-laden erythrocytes. Iron isotopes provide an intrinsic measuring rod of the erythropoietic yield, while Cu isotopes seem to gauge the relative activity of erythropoiesis and lymphatics.

The influence of kinetics on the oxygen isotope composition of calcium carbonate

NASA Astrophysics Data System (ADS)

Watkins, James M.; Nielsen, Laura C.; Ryerson, Frederick J.; DePaolo, Donald J.

2013-08-01

Paleotemperature reconstructions rely on knowledge of the equilibrium separation of oxygen isotopes between aqueous solution and calcium carbonate. Although oxygen isotope separation is expected on theoretical grounds, the temperature-dependence remains uncertain because other factors, such as slow exchange of isotopes between dissolved CO2-species and water, can obscure the temperature signal. This is problematic for crystal growth experiments on laboratory timescales and for interpreting the oxygen isotope composition of crystals formed in natural settings. We present results from experiments in which inorganic calcite is precipitated in the presence of 0.25 μM dissolved bovine carbonic anhydrase (CA). The presence of dissolved CA accelerates oxygen isotope equilibration between the dissolved carbon species CO2, H2CO3, HCO3-, CO32- and water, thereby eliminating this source of isotopic disequilibrium during calcite growth. The experimental results allow us to isolate, for the first time, kinetic oxygen isotope effects occurring at the calcite-water interface. We present a framework of ion-by-ion growth of calcite that reconciles our new measurements with measurements of natural cave calcites that are the best candidate for having precipitated under near-equilibrium conditions. Our findings suggest that isotopic equilibrium between calcite and water is unlikely to have been established in laboratory experiments or in many natural settings. The use of CA in carbonate precipitation experiments offers new opportunities to refine oxygen isotope-based geothermometers and to interrogate environmental variables other than temperature that influence calcite growth rates.

The Most Useful Actinide Isotope: Americium-241.

ERIC Educational Resources Information Center

Navratil, James D.; And Others

1990-01-01

Reviewed is the discovery, nuclear and chemical properties, and uses of an isotope of Americium (Am-241). Production and separation techniques used in industry are emphasized. Processes are illustrated in flow sheets. (CW)

Stable-isotope customer list and summary of shipments, FY 1982

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davis, W.C.

1983-04-01

This compilation is published as an aid to those concerned with the separation and sale of stable isotopes. The inforamtion is divided into four sections: (1) alphabetical list of domestic and foreign customers, showing the stable isotopes purchased during the fiscal year; (2) alphabetical list of isotopes, cross-referenced to customer numbers and divided into domestic and foreign categories; (3) alphabetical list of states and countries, cross-referenced to customer numbers and indicating geographical concentrations of isotope users; and (4) tabulation of the shipments, quantities, and dollars for domestic, foreign, and project categories for each isotope.

A status of progress for the Laser Isotope Separation (LIS) process

NASA Technical Reports Server (NTRS)

Delionback, L. M.

1976-01-01

An overview of the Laser Isotope Separation (LIS) methodology is given together with illustrations showing a simplified version of the LIS technique, an example of the two-photon photoionization category, and a diagram depicting how the energy levels of various isotope influence the LIS process. Applications were proposed for the LIS system which, in addition to enriching uranium, could in themselves develop into programs of tremendous scope and breadth. These include the treatment of radioactive wastes from light-water nuclear reactors, enriching the deuterium isotope to make heavy-water, and enriching the light isotopes of such elements as titanium for aerospace weight-reducing programs. Economic comparisons of the LIS methodology with the current method of gaseous diffusion indicate an overwhelming advantage; the laser process promises to be 1000 times more efficient. The technique could also be utilized in chemical reactions with the tuned laser serving as a universal catalyst to determine the speed and direction of a chemical reaction.

Hybrid isotope separation scheme

DOEpatents

Maya, J.

1991-06-18

A method is described for yielding selectively a desired enrichment in a specific isotope including the steps of inputting into a spinning chamber a gas from which a scavenger, radiating the gas with a wave length or frequency characteristic of the absorption of a particular isotope of the atomic or molecular gas, thereby inducing a photochemical reaction between the scavenger, and collecting the specific isotope-containing chemical by using a recombination surface or by a scooping apparatus. 2 figures.

High-power CO laser with RF discharge for isotope separation employing condensation repression

NASA Astrophysics Data System (ADS)

Baranov, I. Ya.; Koptev, A. V.

2008-10-01

High-power CO laser can be the effective tool in such applications as isotope separation using the free-jet CRISLA method. The way of transfer from CO small-scale experimental installation to industrial high-power CO lasers is proposed through the use of a low-current radio-frequency (RF) electric discharge in a supersonic stream without an electron gun. The calculation model of scaling CO laser with RF discharge in supersonic stream was developed. The developed model allows to calculate parameters of laser installation and optimize them with the purpose of reception of high efficiency and low cost of installation as a whole. The technical decision of industrial CO laser for isotope separation employing condensation repression is considered. The estimated cost of laser is some hundred thousand dollars USA and small sizes of laser head give possibility to install it in any place.

Attomole quantitation of protein separations with accelerator mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogel, J S; Grant, P G; Buccholz, B A

2000-12-15

Quantification of specific proteins depends on separation by chromatography or electrophoresis followed by chemical detection schemes such as staining and fluorophore adhesion. Chemical exchange of short-lived isotopes, particularly sulfur, is also prevalent despite the inconveniences of counting radioactivity. Physical methods based on isotopic and elemental analyses offer highly sensitive protein quantitation that has linear response over wide dynamic ranges and is independent of protein conformation. Accelerator mass spectrometry quantifies long-lived isotopes such as 14C to sub-attomole sensitivity. We quantified protein interactions with small molecules such as toxins, vitamins, and natural biochemicals at precisions of 1-5% . Micro-proton-induced-xray-emission quantifies elemental abundancesmore » in separated metalloprotein samples to nanogram amounts and is capable of quantifying phosphorylated loci in gels. Accelerator-based quantitation is a possible tool for quantifying the genome translation into proteome.« less

The chemical and isotopic differentiation of an epizonal magma body: Organ Needle pluton, New Mexico

USGS Publications Warehouse

Verplanck, P.L.; Farmer, G.L.; McCurry, M.; Mertzman, S.A.

1999-01-01

Major and trace element, and Nd and Sr isotopic compositions of whole rocks and mineral separates from the Oligocene, alkaline Organ Needle pluton (ONP), southern New Mexico, constrain models for the differentiation of the magma body parental to this compositionally zoned and layered epizonal intrusive body. The data reveal that the pluton is rimmed by lower ??(Nd) (~-5) and higher 87Sr/86Sr (~0.7085) syenitic rocks than those in its interior (??(Nd) ~ 2, 87Sr/86Sr ~0.7060) and that the bulk compositions of the marginal rocks become more felsic with decreasing structural depth. At the deepest exposed levels of the pluton, the ??(Nd)~-5 lithology is a compositionally heterogeneous inequigranular syenite. Modal, compositional and isotopic data from separates of rare earth element (REE)-bearing major and accesory mineral phases (hornblende, titanite, apatite, zircon) demonstrate that this decoupling of trace and major elements in the inequigranular syenite results from accumulation of light REE (LREE)-bearing minerals that were evidently separated from silicic magmas as the latter rose along the sides of the magma chamber. Chemical and isotopic data for microgranular mafic enclaves, as well as for restite xenoliths of Precambrian granite wall rock, indicate that the isotopic distinction between the marginal and interior facies of the ONP probably reflects assimilation of the wall rock by ??(Nd) ~-2 mafic magmas near the base of the magma system. Fractional crystallization and crystal liquid separation of the crystally contaminated magma at the base and along the margins of the chamber generated the highly silicic magmas that ultimately pooled at the chamber top.

A novel method for rapid in vitro radiobioassay

NASA Astrophysics Data System (ADS)

Crawford, Evan Bogert

Rapid and accurate analysis of internal human exposure to radionuclides is essential to the effective triage and treatment of citizens who have possibly been exposed to radioactive materials in the environment. The two most likely scenarios in which a large number of citizens would be exposed are the detonation of a radiation dispersal device (RDD, "dirty bomb") or the accidental release of an isotope from an industrial source such as a radioisotopic thermal generator (RTG). In the event of the release and dispersion of radioactive materials into the environment in a large city, the entire population of the city -- including all commuting workers and tourists -- would have to be rapidly tested, both to satisfy the psychological needs of the citizens who were exposed to the mental trauma of a possible radiation dose, and to satisfy the immediate medical needs of those who received the highest doses and greatest levels of internal contamination -- those who would best benefit from rapid, intensive medical care. In this research a prototype rapid screening method to screen urine samples for the presence of up to five isotopes, both individually and in a mixture, has been developed. The isotopes used to develop this method are Co-60, Sr-90, Cs-137, Pu-238, and Am-241. This method avoids time-intensive chemical separations via the preparation and counting of a single sample on multiple detectors, and analyzing the spectra for isotope-specific markers. A rapid liquid-liquid separation using an organic extractive scintillator can be used to help quantify the activity of the alpha-emitting isotopes. The method provides quantifiable results in less than five minutes for the activity of beta/gamma-emitting isotopes when present in the sample at the intervention level as defined by the Centers for Disease Control and Prevention (CDC), and quantifiable results for the activity levels of alpha-emitting isotopes present at their respective intervention levels in approximately 30 minutes of sample preparation and counting time. Radiation detector spectra -- e.g. those from high-purity germanium (HPGe) gamma detectors and liquid scintillation detectors -- which contain decay signals from multiple isotopes often have overlapping signals: the counts from one isotope's decay can appear in energy channels associated with another isotope's decay, complicating the calculation of each isotope's activity. The uncertainties associated with analyzing these spectra have been traced in order to determine the effects of one isotope's count rate on the sensitivity and uncertainty associated with each other isotope. The method that was developed takes advantage of activated carbon filtration to eliminate quenching effects and to make the liquid scintillation spectra from different urine samples comparable. The method uses pulse-shape analysis to reduce the interference from beta emitters in the liquid scintillation spectrum and improve the minimum detectable activity (MDA) and minimum quantifiable activity (MQA) for alpha emitters. The method uses an HPGe detector to quantify the activity of gamma emitters, and subtract their isotopes' contributions to the liquid scintillation spectra via a calibration factor, such that the pure beta and pure alpha emitters can be identified and quantified from the resulting liquid scintillation spectra. Finally, the method optionally uses extractive scintillators to rapidly separate the alpha emitters from the beta emitters when the activity from the beta emitters is too great to detect or quantify the activity from the alpha emitters without such a separation. The method is able to detect and quantify all five isotopes, with uncertainties and biases usually in the 10-40% range, depending upon the isotopic mixtures and the activity ratios between each of the isotopes.

Advances in the measurement of sulfur isotopes by multi-collector ICP-MS (MC-ICP- MS)

NASA Astrophysics Data System (ADS)

Ridley, W. I.; Wilson, S. A.; Anthony, M. W.

2006-12-01

The demonstrated capability to measure 34S/32S by MC-ICP-MS with a precision (2ó) of ~0.2 per mil has many potential applications in geochemistry. However, a number of obstacles limit this potential. First, to achieve the precision indicated above requires sufficient mass resolution to separate isobaric interferences of 16O2 and 17O2 on 32S and 34S, respectively. These requirements for high resolution mean overall instrument sensitivity is reduced. Second, current methods preclude analysis of samples with complex matrices, a common characteristic of sulfur-bearing geologic materials. Here, we describe and discuss a method that provides both efficient removal of matrix constituents, and provides pre-concentration of S, thus overcoming these obstacles. The method involves the separation of sulfur from matrix constituents by high pressure (1000 psi) ion chromatography (HPIC), followed by isotope measurement using MC-ICP-MS. This combination allows for analysis of liquid samples with a wide range of S concentrations. A powerful advantage of this technique is the efficient separation of many sulfur species from matrix cations and anions (for instance in a seawater or acid mine drainage matrix), as well as the separation of sulfur species, e.g., sulfate, sulfite, thiosulfate, thiocynate, from each other for isotope analysis. The automated HPIC system uses a carbonate-bicarbonate eluent with eluent suppression, and has sufficient baseline separation to collect the various sulfur species as pure fractions. The individual fractions are collected over a specific time interval based upon a pre-determined elution profile and peak retention times. The addition of a second ion exchange column into the system allows pre-concentration of sulfur species by 2-3 orders of magnitude for samples that otherwise would have sulfur concentrations too low to provide precise isotopic ratios. The S isotope ratios are measured by MC-ICP-MS using a desolvating sample introduction system, a standard-sample bracketing method employing standards that are well characterized for sulfur isotope composition using stable isotope gas mass spectrometry. Data are collected in time-resolved mode, which reduces analytical time and allows for flexibility in data integration. Preliminary data indicates that sulfur species do not fractionate during the column chemistry.

Investigation of Cu-, Zn- and Fe-containing human brain proteins using isotopic-enriched tracers by LA-ICP-MS and MALDI-FT-ICR-MS

NASA Astrophysics Data System (ADS)

Becker, J. Susanne; Zoriy, Miroslav; Pickhardt, Carola; Przybylski, Michael; Becker, J. Sabine

2005-04-01

Identification of metal-containing proteins and determination of Cu, Fe, Zn concentration in very small protein volumes is of increasing importance in protein research. Proteins containing metal ions were analyzed directly and simultaneously in separated protein spots in two-dimensional gels (2D gels) by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as an element mass spectrometric technique. In order to study the formation of proteins containing Cu, Zn and Fe in a human brain sample, isotopic-enriched tracers (54Fe, 65Cu and 67Zn) were doped to two-dimensional gels of separated Alzheimer-diseased brain proteins after two-dimensional (2D) gel electrophoresis. The protein spots were screened systematically by LA-ICP-MS with respect to these metal ion intensities. 54Fe/56Fe, 65Cu/63Cu and 67Zn/64Zn isotope ratios in metal-containing proteins were measured directly by LA-ICP-MS. The isotope ratio measurements obtained by LA-ICP-MS indicate certain protein spots with a natural isotope composition of Cu, Zn and/or Fe. These proteins already contained the metal investigated in the original proteins and are stable enough to survive the reducing conditions during gel electrophoresis. On the other hand, proteins with a changed isotope ratio of metals in comparison to the isotope ratio in nature demonstrate the accumulation of tracers within the protein complexes during the tracer experiments in 2D gels. The identification of singular protein spots from Alzheimer-diseased brain separated by 2D gel electrophoresis was attempted by biopolymer mass spectrometry using MALDI-FTICR-MS after excision from the 2D gel and tryptic digestion.

Molybdenum isotopic evidence for the origin of chondrules and a distinct genetic heritage of carbonaceous and non-carbonaceous meteorites

NASA Astrophysics Data System (ADS)

Budde, Gerrit; Burkhardt, Christoph; Brennecka, Gregory A.; Fischer-Gödde, Mario; Kruijer, Thomas S.; Kleine, Thorsten

2016-11-01

Nucleosynthetic isotope anomalies are powerful tracers to determine the provenance of meteorites and their components, and to identify genetic links between these materials. Here we show that chondrules and matrix separated from the Allende CV3 chondrite have complementary nucleosynthetic Mo isotope anomalies. These anomalies result from the enrichment of a presolar carrier enriched in s-process Mo into the matrix, and the corresponding depletion of this carrier in the chondrules. This carrier most likely is a metal and so the uneven distribution of presolar material probably results from metal-silicate fractionation during chondrule formation. The Mo isotope anomalies correlate with those reported for W isotopes on the same samples in an earlier study, suggesting that the isotope variations for both Mo and W are caused by the heterogeneous distribution of the same carrier. The isotopic complementary of chondrules and matrix indicates that both components are genetically linked and formed together from one common reservoir of solar nebula dust. As such, the isotopic data require that most chondrules formed in the solar nebula and are not a product of protoplanetary impacts. Allende chondrules and matrix together with bulk carbonaceous chondrites and some iron meteorites (groups IID, IIIF, and IVB) show uniform excesses in 92Mo, 95Mo, and 97Mo that result from the addition of supernova material to the solar nebula region in which these carbonaceous meteorites formed. Non-carbonaceous meteorites (enstatite and ordinary chondrites as well as most iron meteorites) do not contain this material, demonstrating that two distinct Mo isotope reservoirs co-existed in the early solar nebula that remained spatially separated for several million years. This separation was most likely achieved through the formation of the gas giants, which cleared the disk between the inner and outer solar system regions parental to the non-carbonaceous and carbonaceous meteorites. The Mo isotope dichotomy of meteorites provides a new means to determine the provenance of meteoritic and planetary materials, and to assess genetic links between chondrites and differentiated meteorites.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faye, S. A.; Shaughnessy, D. A.

The objective of this project is to provide a comprehensive study on the production routes and chemical separation requirements for activation products, fission products, and actinides required for the creation of realistic post-detonation surrogate debris. Isotopes that have been prioritized by debris diagnosticians will be examined for their ability to be produced at existing irradiation sources, production rates, and availability of target materials, and chemical separation procedures required to rapidly remove the products from the bulk target matrix for subsequent addition into synthetic debris samples. The characteristics and implications of the irradiation facilities on the isotopes of interest will bemore » addressed in addition to a summary of the isotopes that are already regularly produced. This is a planning document only.« less

Determination of Plutonium Isotope Ratios at Very Low Levels by ICP-MS using On-Line Electrochemically Modulated Separations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liezers, Martin; Lehn, Scott A; Olsen, Khris B

2009-10-01

Electrochemically modulated separations (EMS) are shown to be a rapid and selective means of extracting and concentrating Pu from complex solutions prior to isotopic analysis by inductively coupled plasma mass spectrometry (ICP-MS). This separation is performed in a flow injection mode, on-line with the ICP-MS. A three-electrode, flow-by electrochemical cell is used to accumulate Pu at an anodized glassy carbon electrode by redox conversion of Pu(III) to Pu (IV&VI). The entire process takes place in 2% v/v (0.46M) HNO 3. No redox chemicals or acid concentration changes are required. Plutonium accumulation and release is redox dependent and controlled by themore » applied cell potential. Thus large transient volumetric concentration enhancements can be achieved. Based on more negative U(IV) potentials relative to Pu(IV), separation of Pu from uranium is efficient, thereby eliminating uranium hydride interferences. EMS-ICP-MS isotope ratio measurement performance will be presented for femtogram to attogram level plutonium concentrations.« less

Hydrogen Isotope Measurements of Organic Acids and Alcohols by Pyrolysis-GC-MS-TC-IRMS

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Fu, Qi; Niles, Paul B.

2011-01-01

One possible process responsible for methane generation on Mars is abiotic formation by Fischer-Tropsch-type (FTT) synthesis during serpentinization reactions. Measurement of carbon and hydrogen isotopes of intermediary organic compounds can help constrain the origin of this methane by tracing the geochemical pathway during formation. Of particular interest within the context of this work is the isotopic composition of organic intermediaries produced on the surfaces of mineral catalysts (i.e. magnetite) during hydrothermal experiments, and the ability to make meaningful and reproducible hydrogen isotope measurements. Reported here are results of experiments to characterize the hydrogen isotope composition of low molecular weight organic acids and alcohols. The presence of these organic compounds has been suggested by others as intermeadiary products made during mineral surface catalyzed reactions. This work compliments our previous study characterizing the carbon isotope composition of similar low molecular weight intermediary organic compounds (Socki, et al, American Geophysical Union Fall meeting, Abstr. #V51B-2189, Dec., 2010). Our hydrogen isotope measurements utilize a unique analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-High Temperature Conversion-Isotope Ratio Mass Spectrometry (Py-GC-MS-TC-IRMS). Our technique is unique in that it carries a split of the pyrolyzed GC-separated product to a Thermo DSQ-II? quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of separated organic compounds, therefore both chemical and isotopic measurements can be carried out simultaneously on the same sample.

Separation of Platinum from Palladium and Iridium in Iron Meteorites and Accurate High-Precision Determination of Platinum Isotopes by Multi-Collector ICP-MS.

PubMed

Hunt, Alison C; Ek, Mattias; Schönbächler, Maria

2017-12-01

This study presents a new measurement procedure for the isolation of Pt from iron meteorite samples. The method also allows for the separation of Pd from the same sample aliquot. The separation entails a two-stage anion-exchange procedure. In the first stage, Pt and Pd are separated from each other and from major matrix constituents including Fe and Ni. In the second stage, Ir is reduced with ascorbic acid and eluted from the column before Pt collection. Platinum yields for the total procedure were typically 50-70%. After purification, high-precision Pt isotope determinations were performed by multi-collector ICP-MS. The precision of the new method was assessed using the IIAB iron meteorite North Chile. Replicate analyses of multiple digestions of this material yielded an intermediate precision for the measurement results of 0.73 for ε 192 Pt, 0.15 for ε 194 Pt and 0.09 for ε 196 Pt (2 standard deviations). The NIST SRM 3140 Pt solution reference material was passed through the measurement procedure and yielded an isotopic composition that is identical to the unprocessed Pt reference material. This indicates that the new technique is unbiased within the limit of the estimated uncertainties. Data for three iron meteorites support that Pt isotope variations in these samples are due to exposure to galactic cosmic rays in space.

Compound-specific isotope analysis: Questioning the origins of a trichloroethene plume

USGS Publications Warehouse

Eberts, S.M.; Braun, C.; Jones, S.

2008-01-01

Stable carbon isotope ratios of trichloroethene (TCE), cis-1,2- dichloroethene, and trans-1,2-dichloroethene were determined by use of gas chromatography-combustion-isotope ratio mass spectroscopy to determine whether compound-specific stable carbon isotopes could be used to help understand the origin and history of a TCE groundwater plume in Fort Worth, TX. Calculated ??13C values for total chlorinated ethenes in groundwater samples, which can approximate the ??13C of a spilled solvent if all degradation products are accounted for, were useful for determining whether separate lobes of the plume resulted from different sources. Most notably, values for one lobe, where tetrachloroethene (PCE) has been detected periodically, were outside the range for manufactured TCE but within the range for manufactured PCE, whereas values for a separate lobe, which is downgradient of reported TCE spills, were within the range for manufactured TCE. Copyright ?? Taylor & Francis Group, LLC.

Volatile element depletion and K-39/K-41 fractionation in lunar soils

NASA Technical Reports Server (NTRS)

Church, S. E.; Tilton, G. R.; Wright, J. E.; Lee-Hu, C.-N.

1976-01-01

Evidence for selective loss and isotopic fractionation (in the case of K) of volatile elements during formation of agglutinates by micrometeoritic bombardment of lunar soils is presented. Concentrations and isotopic compositions of volatile elements (K, Rb, Pb) and nonvolatile elements (U, Th, Ba, Sr, rare earths) in separates taken from soils 14163, 14259, 15041, 68501, and 71500 are examined. Rayleigh fractionation calculations applied to K-39/K-41 isotopic data indicate ten-fold recycling of bulk soil, to account for observed isotopic anomalies. The lunar soil fines fraction seems to be a site of deposition for volatile or labile Pb produced during agglutination. Local fines (below 75 microns) are viewed as representative of the parent material for agglutinates formed in situ by micrometeoritic impact. Magnetic separation of agglutinates from soil 68501 revealed a bimodal population, with one class comprising welded blocky magnetic glasses.

Biomedical research applications of electromagnetically separated enriched stable isotopes

NASA Astrophysics Data System (ADS)

Lambrecht, R. M.

The current and projected annual requirements through 1985 for stable isotopes enriched by electromagnetic separation methods were reviewed for applications in various types of biomedical research: (1) medical radiosiotope production, labeled compounds, and potential radio-pharmaceuticals; (2) nutrition, food science, and pharmacology: (3) metallobiochemistry and environmental toxicology; (4) nuclear magnetic resonance, electron paramagnetic resonance, and moessbauer spectroscopy in biochemical, biophysical, and biomedical research; and (5) miscellaneous advances in radioactive and nonradioactive tracer technology. Radioisotopes available from commercial sources or routinely used in clinical nuclear medicine were excluded. Current requirements for enriched stable isotopes in biomedical research are not being satisfied. Severe shortages exist for Mg 26, Ca 43, Zn 70, Se 76, Se 77, Se 78, Pd 102, Cd 111, Cd 113, and Os 190. Many interesting and potentially important investigations in biomedical research require small quantities of specific elements at high isotopic enrichments.

Segregation of isotopes of heavy metals due to light-induced drift: results and problems

NASA Astrophysics Data System (ADS)

Sapar, A.; Aret, A.; Poolamäe, R.; Sapar, L.

2008-04-01

Atutov and Shalagin (1988) proposed light-induced drift (LID) as a physically well understandable mechanism to explain the formation of isotopic anomalies observed in CP stars. We have generalized the theory of LID and applied it to diffusion of heavy elements and their isotopes in quiescent atmospheres of CP stars. Diffusional segregation of isotopes of chemical elements is described by the equations of continuity and diffusion velocity. Computations of evolutionary sequences for the abundances of mercury isotopes in several model atmospheres have been made, using the Fortran 90 program SMART composed by the authors. Results confirm predominant role of LID in separation of isotopes.

Theoretical description of quantum mechanical permeation of graphene membranes by charged hydrogen isotopes

NASA Astrophysics Data System (ADS)

Mazzuca, James W.; Haut, Nathaniel K.

2018-06-01

It has been recently shown that in the presence of an applied voltage, hydrogen and deuterium nuclei can be separated from one another using graphene membranes as a nuclear sieve, resulting in a 10-fold enhancement in the concentration of the lighter isotope. While previous studies, both experimental and theoretical, have attributed this effect mostly to differences in vibrational zero point energy (ZPE) of the various isotopes near the membrane surface, we propose that multi-dimensional quantum mechanical tunneling of nuclei through the graphene membrane influences this proton permeation process in a fundamental way. We perform ring polymer molecular dynamics calculations in which we include both ZPE and tunneling effects of various hydrogen isotopes as they permeate the graphene membrane and compute rate constants across a range of temperatures near 300 K. While capturing the experimentally observed separation factor, our calculations indicate that the transverse motion of the various isotopes across the surface of the graphene membrane is an essential part of this sieving mechanism. An understanding of the multi-dimensional quantum mechanical nature of this process could serve to guide the design of other such isotopic enrichment processes for a variety of atomic and molecular species of interest.

Theoretical description of quantum mechanical permeation of graphene membranes by charged hydrogen isotopes.

PubMed

Mazzuca, James W; Haut, Nathaniel K

2018-06-14

It has been recently shown that in the presence of an applied voltage, hydrogen and deuterium nuclei can be separated from one another using graphene membranes as a nuclear sieve, resulting in a 10-fold enhancement in the concentration of the lighter isotope. While previous studies, both experimental and theoretical, have attributed this effect mostly to differences in vibrational zero point energy (ZPE) of the various isotopes near the membrane surface, we propose that multi-dimensional quantum mechanical tunneling of nuclei through the graphene membrane influences this proton permeation process in a fundamental way. We perform ring polymer molecular dynamics calculations in which we include both ZPE and tunneling effects of various hydrogen isotopes as they permeate the graphene membrane and compute rate constants across a range of temperatures near 300 K. While capturing the experimentally observed separation factor, our calculations indicate that the transverse motion of the various isotopes across the surface of the graphene membrane is an essential part of this sieving mechanism. An understanding of the multi-dimensional quantum mechanical nature of this process could serve to guide the design of other such isotopic enrichment processes for a variety of atomic and molecular species of interest.

Fast, low-level detection of strontium-90 and strontium-89 in environmental samples by collinear resonance ionization spectroscopy

NASA Astrophysics Data System (ADS)

Monz, L.; Hohmann, R.; Kluge, H.-J.; Kunze, S.; Lantzsch, J.; Otten, E. W.; Passler, G.; Senne, P.; Stenner, J.; Stratmann, K.; Swendt, K.; Zimmer, K.; Herrmann, G.; Trautmann, N.; Walter, K.

1993-12-01

Environmental assessment in the wake of a nuclear accident requires the rapid determination of the radiotoxic isotopes 89Sr and 90Sr. Useful measurements must be able to detect 10 8 atoms in the presence of about 10 18 atoms of the stable, naturally occurring isotopes. This paper describes a new approach to this problem using resonance ionization spectroscopy in collinear geometry, combined with classical mass separation. After collection and chemical separation, the strontium from a sample is surface-ionized and the ions are accelerated to an energy of about 30 keV. Initially, a magnetic mass separator provides an isotopic selectivity of about 10 6. The ions are then neutralized by charge exchange and the resulting fast strontium atoms are selectively excited into high-lying atomic Rydberg states by narrow-band cw laser light in collinear geometry. The Rydberg atoms are then field-ionized and detected. Thus far, a total isotopic selectivity of S > 10 10 and an overall efficiency of ξ = 5 × 10 -6 have been achieved. The desired detection limit of 10 8 atoms 90Sr has been demonstrated with synthetic samples.

Modeling of Isotope Fractionation in Stratospheric CO2, N2O, CH4, and O3: Investigations of Stratospheric Chemistry and Transport, Stratosphere-Troposphere Exchange, and Their Influence on Global Isotope Budgets

NASA Technical Reports Server (NTRS)

Boering, Kristie A.; Connell, Peter; Rotman, Douglas

2004-01-01

We investigated the isotopic fractionation of CH4 and hydrogen (H2) in the stratosphere by incorporating isotope-specific rate coefficients into the Lawrence Livermore National Laboratory (LLNL) 2D model and comparing the model results with new observations from the NASA ER-2 aircraft (funded through a separate task under the Upper Atmosphere Research Program). The model results reveal that fractionation which occurs in the stratosphere has a significant influence on isotope compositions in the free troposphere, an important point which had previously been ignored, unrecognized or unquantified for many long-lived trace gases, including CH4 and H2 which we have focused our efforts on to date. Our analyses of the model results and new isotope observations have also been used to test how well the kinetic isotope effects are known, at least to within the uncertainties in model chemistry and transport. Overall, these results represent an important step forward in our understanding of isotope fractionation in the atmosphere and demonstrate that stratospheric isotope fractionation cannot be ignored in modeling studies which use isotope observations in the troposphere to infer the global budgets of CH4 (an important greenhouse gas) and of H2 (a gas whose atmospheric budget must be better quantified, particularly before a large human perturbation from fuel cell use is realized). Our analyses of model results and observations from the NASA ER-2 aircraft are briefly summarized separately below for CH4, H2, and H2O and for the contribution of these modeling studies to date to our understanding of isotope fractionation for N2O, CO2, and O3 as well.

Laser ablation inductively coupled plasma mass spectrometry for direct isotope ratio measurements on solid samples

NASA Astrophysics Data System (ADS)

Pickhardt, Carola; Dietze, Hans-Joachim; Becker, J. Sabine

2005-04-01

Isotope ratio measurements have been increasingly used in quite different application fields, e.g., for the investigation of isotope variation in nature, in geoscience (geochemistry and geochronology), in cosmochemistry and planetary science, in environmental science, e.g., in environmental monitoring, or by the application of the isotope dilution technique for quantification purposes using stable or radioactive high-enriched isotope tracers. Due to its high sensitivity, laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) is today a challenging mass spectrometric technique for the direct determination of precise and accurate isotope ratios in solid samples. In comparison to laser ablation quadrupole ICP-MS (LA-ICP-QMS), laser ablation coupled to a double-focusing sector field ICP-MS (LA-ICP-SFMS) with single ion detection offers a significant improvement of sensitivity at low mass resolution, whereby isotope ratios can be measured with a precision to 0.1% relative standard deviation (R.S.D.). In LA-ICP-SFMS, many disturbing isobaric interferences of analyte and molecular ions can be separated at the required mass resolution (e.g., 40Ar16O+ and 56Fe+ for iron isotope ratio measurements). The precision on isotope ratio measurements was improved by one order of magnitude via the simultaneous detection of mass-separated ion currents of isotopes using multiple ion collectors in LA-ICP-MS (LA-MC-ICP-MS). The paper discusses the state of the art, the challenges and limits in isotope ratio measurements by LA-ICP-MS using different instrumentations at the trace and ultratrace level in different fields of application as in environmental and biological research, geochemistry and geochronology with respect to their precision and accuracy.

Mound Laboratory activities for the Division of Physical Research: July--December 1975

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1976-05-14

Research and development are reported in the following areas: isotope separation and production for Ar, C, He, Kr, Ne, O, S, and Xe; testing of cubic B crystals for superconductivity; metal hydride research on band theory and electronic structure and spin-lattice relaxation times for VH/sub x/; separation chemistry of Pu, /sup 231/Pa, /sup 230/Th, /sup 229/Th, and /sup 234/U; adsorption of U and Pu by bone char; separation research for Ca and S isotopes; molecular beam scattering for Ar--Kr; and transport properties for the systems Ne--Ar, Ne--Kr, and Ar--Kr. (JSR)

Method for isotopic analysis of chlorinated organic compounds

DOEpatents

Holt, Ben D.; Sturchio, Neil C.

1999-01-01

The present invention provides a method for preparing a VOC sample for carbon and chlorine isotope ratio analysis by mass spectrometer. A VOC sample is placed in a combustion tube and reacted with CuO to form CO.sub.2 and CuCl. The CO.sub.2 is then extracted and analyzed for the carbon isotope ratio. The CuCl is separated from the excess CuO and reacted with CH.sub.3 I to form CH.sub.3 Cl, extracted and analyzed for chlorine isotope ratio.

High-Precision Measurement of 13C/12C Isotopic Ratio Using Gas Chromatography-Combustion-Cavity Ring-Down Spectroscopy

NASA Astrophysics Data System (ADS)

Saad, N.; Kuramoto, D. S.; Haase, C.; Crosson, E.; Tan, S.; Zare, R. N.

2009-12-01

Light stable isotope analysis, and in particular, compound specific isotopic analysis (CSIA), is a valuable tool to elucidate pathways and provide a better insight into biological, ecological, and geological systems. We present here the results of compound-specific isotopic carbon analysis of short chain hydrocarbons using the world’s first combination of gas chromatography, combustion interface, and cavity ring-down spectroscopy (GC-C-CRDS). Cavity ring-down spectroscopy (CRDS) is a highly sensitive optical spectroscopy, one application of which is to measure the stable isotopic ratios in small molecules. Because it uses a highly reflective optical cavity with many kilometers effective path length, CRDS provides some of the most sensitive and precise optical absorption measurements. Most optical spectroscopy isotopic analysis measures the quantities of each isotopologue independently using their distinct ro-vibrational spectra. The most common isotopes measured with optical spectroscopy are 13C and 12C in carbon dioxide. However, the isotopes of hydrogen, oxygen, and sulfur have also been measured. Unlike isotope ratio mass spectrometry (IRMS), optical spectroscopy can distinguish among isobars, which have essentially identical m/z ratios. The combination of chemical separation, chemical conversion, and CRDS makes a nearly universal tool for isotopic analysis of mixtures. In addition, CRDS can tolerate a variety of compounds mixed with the target. For example, CRDS can measure carbon dioxide and its isotopic 13C/12C ratio in the presence of oxygen. Using the novel GC-C-CRDS system, we injected a 75-microliter mixture of approximately equal quantities of methane, ethane, and propane into a gas chromatograph using helium as carrier gas. The methane, ethane, and propane were separated in time by 100 to 200 seconds after the chromatograph. Oxygen gas was added, and the hydrocarbons were combusted in a catalytic combustor with platinum and nickel, held at 1150oC. The combusted products were combined with dry nitrogen gas to provide sufficient gas flow for the CRDS analyzer, which measured the 13C/12C isotopic ratio of the separated methane, ethane, and propane, obtaining a precision of 0.95 permil or better. The calibration accuracy was within 3 permil of the values determined using IRMS. The current CRDS-based system is less expensive, does not require highly trained personnel to operate, and is portable, compared with IRMS. We anticipate that advances in spectroscopic analysis will improve the precision and accuracy of the CRDS isotopic measurement, making it comparable with IRMS.

Polyatomic interferences on high precision uranium isotope ratio measurements by MC-ICP-MS: Applications to environmental sampling for nuclear safeguards

DOE PAGES

Pollington, Anthony D.; Kinman, William S.; Hanson, Susan K.; ...

2015-09-04

Modern mass spectrometry and separation techniques have made measurement of major uranium isotope ratios a routine task; however accurate and precise measurement of the minor uranium isotopes remains a challenge as sample size decreases. One particular challenge is the presence of isobaric interferences and their impact on the accuracy of minor isotope 234U and 236U measurements. Furthermore, we present techniques used for routine U isotopic analysis of environmental nuclear safeguards samples and evaluate polyatomic interferences that negatively impact accuracy as well as methods to mitigate their impacts.

Development of high through-put Sr isotope analysis for monitoring reservoir integrity for CO{sub 2} storage.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wall, Andy; Jain, Jinesh; Stewart, Brian

2012-01-01

Recent innovations in multi-collector ICP-mass spectrometry (MC-ICP-MS) have allowed for rapid and precise measurements of isotope ratios in geological samples. Naturally occurring Sr isotopes has the potential for use in Monitoring, Verification, and Accounting (MVA) associated with geologic CO2 storage. Sr isotopes can be useful for: Sensitive tracking of brine migration; Determining seal rock leakage; Studying fluid/rock reactions. We have optimized separation chemistry procedures that will allow operators to prepare samples for Sr isotope analysis off site using rapid, low cost methods.

Separation of Calcium Isotopes by Counter-Current Electro-Migration in Molten Salts; SEPARATION DES ISOTOPES DU CALCIUM PAR ELECTRO-MIGRATION A CONTRECOURANT EN SELS FONDUS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menes, F.; Dirian, G.; Roth, E.

1962-01-01

The method of counter-current electromigration in molten salts was applied to CaBr/sub 2/ with an alkali metal bromide added to the cathode compartment. Enrichments on Ca/sup 46/ greater than a factor of two were obtained at the anode. The mass effect was found to be about 0.06. An estimation of the cost of energy for a process based on this method was made. (auth)

Recent Advances in SRS on Hydrogen Isotope Separation Using Thermal Cycling Absorption Process

DOE PAGES

Xiao, Xin; Sessions, Henry T.; Heung, L. Kit

2015-02-01

The recent Thermal Cycling Absorption Process (TCAP) advances at Savannah River Site (SRS) include compressor-free concept for heating/cooling, push and pull separation using an active inverse column, and compact column design. The new developments allow significantly higher throughput and better reliability from 1/10th of the current production system’s footprint while consuming 60% less energy. Various versions are derived in the meantime for external customers to be used in fusion energy projects and medical isotope production.

Dissolution of barite for the analysis of strontium isotopes and other chemical and isotopic variations using aqueous sodium carbonate

USGS Publications Warehouse

Breit, G.N.; Simmons, E.C.; Goldhaber, M.B.

1985-01-01

A simple procedure for preparing barite samples for chemical and isotopic analysis is described. Sulfate ion, in barite, in the presence of high concentrations of aqueous sodium carbonate, is replaced by carbonate. This replacement forms insoluble carbonates with the cations commonly in barite: Ba, Sr, Ca and Pb. Sulfate is released into the solution by the carbonate replacement and is separated by filtration. The aqueous sulfate can then be reprecipitated for analysis of the sulfur and oxygen isotopes. The cations in the carbonate phase can be dissolved by acidifying the solid residue. Sr can be separated from the solution for Sr isotope analysis by ion-exchange chromatography. The sodium carbonate used contains amounts of Sr which will affect almost all barite 87Sr 86Sr ratios by less than 0.00001 at 1.95?? of the mean. The procedure is preferred over other techniques used for preparing barite samples for the determination of 87Sr 86Sr ratios because it is simple, rapid and enables simultaneous determination of many compositional parameters on the same material. ?? 1985.

Highly Siderophile Elements, 187Re-187 Os and 182Hf-182W Isotopic Systematics of Early Solar System Materials: Constraining the Early Evolution of Chondritic and Achondritic Parent Bodies

NASA Astrophysics Data System (ADS)

Archer, Gregory J.

Highly siderophile element (HSE) abundances and 187Re- 187Os isotopic systematics for H chondrites and ungrouped achondrites, as well as 182Hf-182W isotopic systematics of H and CR chondrites are reported. Achondrite fractions with higher HSE abundances show little disturbance of 187Re-187Os isotopic systematics. By contrast, isotopic systematics for lower abundance fractions are consistent with minor Re mobilization. For magnetically separated H chondrite fractions, the magnitudes of disturbance for the 187Re-187Os isotopic system follow the trend coarse-metal isotopic system follow the trend coarse-metal

Influence of uncertainties of isotopic composition of the reprocessed uranium on effectiveness of its enrichment in gas centrifuge cascades

NASA Astrophysics Data System (ADS)

Smirnov, A. Yu; Mustafin, A. R.; Nevinitsa, V. A.; Sulaberidze, G. A.; Dudnikov, A. A.; Gusev, V. E.

2017-01-01

The effect of the uncertainties of the isotopic composition of the reprocessed uranium on its enrichment process in gas centrifuge cascades while diluting it by adding low-enriched uranium (LEU) and waste uranium. It is shown that changing the content of 232U and 236U isotopes in the initial reprocessed uranium within 15% (rel.) can significantly change natural uranium consumption and separative work (up to 2-3%). However, even in case of increase of these parameters is possible to find the ratio of diluents, where the cascade with three feed flows (depleted uranium, LEU and reprocessed uranium) will be more effective than ordinary separation cascade with one feed point for producing LEU from natural uranium.

Boron isotope fractionation in liquid chromatography with boron-specific resins as column packing material

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oi, Takao; Shimazaki, Hiromi; Ishii, Reiko

1997-07-01

Boron-specific resins with n-methyl glucamine as the functional group were used as column packing material of liquid chromatography for boron isotope separation. The shapes of chromatograms in reverse breakthrough experiments were heavily dependent on the pH of the eluents, and there existed a pH value at which a chromatogram of the displacement type was realized nearly ideally. The value of the single-stage separation factor for the boron isotopes varied between 1.010 and 1.022, depending on the temperature and the form of the resins. The existence of the three-coordinate boron species in addition to the four-coordinate species in the resin phasemore » is suggested.« less

A Mass Spectrometry Study of Isotope Separation in the Laser Plume

NASA Astrophysics Data System (ADS)

Suen, Timothy Wu

Accurate quantification of isotope ratios is critical for both preventing the development of illicit weapons programs in nuclear safeguards and identifying the source of smuggled material in nuclear forensics. While isotope analysis has traditionally been performed by mass spectrometry, the need for in situ measurements has prompted the development of optical techniques, such as laser-induced breakdown spectroscopy (LIBS) and laser ablation molecular isotopic spectrometry (LAMIS). These optical measurements rely on laser ablation for direct solid sampling, but several past studies have suggested that the distribution of isotopes in the ablation plume is not uniform. This study seeks to characterize isotope separation in the laser plume through the use of orthogonal-acceleration time-of-flight mass spectrometry. A silver foil was ablated with a Nd:YAG at 355 nm at an energy of 50 muJ with a spot size of 71 mum, for a fluence of 1.3 J/cm2 and an irradiance of 250 MW/cm2. Flat-plate repellers were used to sample the plume, and a temporal profile of the ions was obtained by varying the time delay on the high-voltage pulse. A spatial profile along the axis of the plume was generated by changing the position of the sample, which yielded snapshots of the isotopic composition with time. In addition, the reflectron time-of-flight system was used as an energy filter in conjunction with the repellers to sample slices of the laser plasma orthogonal to the plume axis. Mass spectrometry of the plume revealed a fast ion distribution and a slow ion distribution. Measurements taken across the entire plume showed the fast 109Ag ions slightly ahead in both space and time, causing the 107Ag fraction to drop to 0.34 at 3 mus, 4 mm from the sample surface. Although measurements centered on the near side of the plume did not show isotope separation, the slow ions on the far side of the plume included much more 109Ag than 107Ag. In addition to examining the isotope content of the ablation plume, this study has developed a mass spectrometry characterization technique that may be useful for investigating chemical reactions during laser ablation.

10 CFR 75.4 - Definitions.

Code of Federal Regulations, 2013 CFR

2013-01-01

...); (3) A fuel fabrication plant; (4) An enrichment plant or isotope separation plant for the separation..., irradiated fuel element chopping machines, and hot cells. Nuclear fuel cycle-related research and development...

10 CFR 75.4 - Definitions.

Code of Federal Regulations, 2014 CFR

2014-01-01

...); (3) A fuel fabrication plant; (4) An enrichment plant or isotope separation plant for the separation..., irradiated fuel element chopping machines, and hot cells. Nuclear fuel cycle-related research and development...

A Critical Look at the Combined Use of Sulfur and Oxygen Isotopes to Study Microbial Metabolisms in Methane-Rich Environments

PubMed Central

Antler, Gilad; Pellerin, André

2018-01-01

Separating the contributions of anaerobic oxidation of methane and organoclastic sulfate reduction in the overall sedimentary sulfur cycle of marine sediments has benefited from advances in isotope biogeochemistry. Particularly, the coupling of sulfur and oxygen isotopes measured in the residual sulfate pool (δ18OSO4 vs. δ34SSO4). Yet, some important questions remain. Recent works have observed patterns that are inconsistent with previous interpretations. We differentiate the contributions of oxygen and sulfur isotopes to separating the anaerobic oxidation of methane and organoclastic sulfate reduction into three phases; first evidence from conventional high methane vs. low methane sites suggests a clear relationship between oxygen and sulfur isotopes in porewater and the metabolic process taking place. Second, evidence from pure cultures and organic matter rich sites with low levels of methane suggest the signatures of both processes overlap and cannot be differentiated. Third, we take a critical look at the use of oxygen and sulfur isotopes to differentiate metabolic processes (anaerobic oxidation of methane vs. organoclastic sulfate reduction). We identify that it is essential to develop a better understanding of the oxygen kinetic isotope effect, the degree of isotope exchange with sulfur intermediates as well as establishing their relationships with the cell-specific metabolic rates if we are to develop this proxy into a reliable tool to study the sulfur cycle in marine sediments and the geological record. PMID:29681890

Scalable and efficient separation of hydrogen isotopes using graphene-based electrochemical pumping

NASA Astrophysics Data System (ADS)

Lozada-Hidalgo, M.; Zhang, S.; Hu, S.; Esfandiar, A.; Grigorieva, I. V.; Geim, A. K.

2017-05-01

Thousands of tons of isotopic mixtures are processed annually for heavy-water production and tritium decontamination. The existing technologies remain extremely energy intensive and require large capital investments. New approaches are needed to reduce the industry's footprint. Recently, micrometre-size crystals of graphene are shown to act as efficient sieves for hydrogen isotopes pumped through graphene electrochemically. Here we report a fully-scalable approach, using graphene obtained by chemical vapour deposition, which allows a proton-deuteron separation factor of around 8, despite cracks and imperfections. The energy consumption is projected to be orders of magnitude smaller with respect to existing technologies. A membrane based on 30 m2 of graphene, a readily accessible amount, could provide a heavy-water output comparable to that of modern plants. Even higher efficiency is expected for tritium separation. With no fundamental obstacles for scaling up, the technology's simplicity, efficiency and green credentials call for consideration by the nuclear and related industries.

Laser photochemical lead isotopes separation for harmless nuclear power engineering

NASA Astrophysics Data System (ADS)

Bokhan, P. A.; Fateev, N. V.; Kim, V. A.; Zakrevsky, D. E.

2016-09-01

The collisional quenching of the metastable 3 P 1,2 and 1 D 2 lead atoms is studied experimentally in the gas flow of the lead atoms, reagent-molecules and a carrier gas Ar. The experimental parameters were similar to the conditions that are required in the operation of the experimental setup for photochemical isotope separation. Excited atoms are generated under electron impact conditions created by a gas glow discharge through the mixture of gases and monitored photoelectrically by attenuation of atomic resonance radiation from hollow cathode 208Pb lamp. The decay of the excited atoms has been studied in the presence various molecules and total cross section data are reported. The flow tube measurements has allowed to separate the physical and chemical quenching channels and measure the rates of the chemical reaction excited lead with N2O, CH2Cl2, SF6 and CuBr molecules. These results are discussed in the prospects of the obtaining isotopically modified lead as a promising coolant in the reactors on the fast-neutron.

The influence of lithology on surface water sources | Science ...

EPA Pesticide Factsheets

Understanding the temporal and spatial variability of surface water sources within a basin is vital to our ability to manage the impacts of climate variability and land cover change. Water stable isotopes can be used as a tool to determine geographic and seasonal sources of water at the basin scale. Previous studies in the Coastal Range of Oregon reported that the variation in the isotopic signatures of surface water does not conform to the commonly observed “rainout effect”, which exhibits a trend of increasing isotopic depletion with rising elevation. The primary purpose of this research is to investigate the mechanisms governing seasonal and spatial variations in the isotopic signature of surface waters within the Marys River Basin, located in the leeward side of the Oregon Coastal Range. Surface water and precipitation samples were collected every 2-3 weeks for isotopic analysis of δ18O and δ2H for one year. Results indicate a significant difference in isotopic signature between watersheds underlain by basalt and sandstone. The degree of separation was the most distinct during the summer when low flows reflect deeper groundwater sources, whereas isotopic signatures during the rainy season (fall and winter) showed a greater degree of similarity between the two lithologies. This indicates that baseflow within streams drained by sandstone versus basalt is being supplied from two distinctly separate water sources. In addition, Marys River flow at the outle

Isotopic Abundances as Tracers of the Processes of Lunar Formation

NASA Astrophysics Data System (ADS)

Pahlevan, K.

2011-12-01

Ever since Apollo, isotopic abundances have been used as tracers to study lunar formation, in particular, to study the sources of the lunar material. In the last decade, however, a number of isotopic similarities have been observed between the lunar samples and the Earth's mantle such that these two reservoirs are now known to be indistinguishable from one another to high precision for a variety of isotopic tracers. This occurs against the backdrop of a Solar System that exhibits widespread heterogeneity with respect to these tracers, a situation that strongly argues that the source of the lunar material is the silicate Earth. To reconcile this observation with the fact that the Moon is thought to result from the collision of two isotopically distinct planetary bodies, a scenario has emerged in which the material from the Moon-forming impactor and the proto-Earth are homogenized in the aftermath of the giant impact. This takes place via turbulent mixing in the time after the giant impact but before lunar accretion while the Earth-Moon system exists in the form of a continuous, high-temperature fluid. Importantly, this high-temperature phase of the evolution occurs in the presence of at least two phases (liquid + vapor) making possible chemical and isotopic fractionation. While equilibrium isotopic fractionation tends to zero at high temperatures, and the post giant impact environment experiences some of the highest temperatures encountered in the Earth sciences, there are several factors that nevertheless make equilibrium isotope effects important probes of this early evolution. (1) Because the vaporization of silicates involves decomposition reactions, the bonding environment for elements in the liquid is often very different from that in the vapor. This difference makes the magnitude of isotopic fractionation intrinsically large, even at the relevant temperatures. (2) Since the isotopic composition of a silicate liquid and co-existing vapor are distinctly different, if the Moon preferentially forms from the liquid or vapor relative to the Earth, mass-dependent isotopic differences at the planetary scale may arise. The large density contrast between liquid and vapor makes phase separation possible. (3) The precision with which planetary isotopic compositions can be determined has increased such that measurements are sensitive to even small degrees of high-temperature phase separation. Using thermodynamic models of silicate liquids to determine the partial vaporization behavior of the major elements, we will present calculations of isotopic fractionation due to liquid-vapor separation for the elements iron, magnesium, silicon, and oxygen. Improvements in analytical precision have largely settled the question of the source of the lunar material - the Earth's mantle - and isotopic measurements are now beginning to yield insight into the high-temperatures processes operating during lunar formation.

Determination of plutonium isotopes (238Pu, 239Pu, 240Pu, 241Pu) in environmental samples using radiochemical separation combined with radiometric and mass spectrometric measurements.

PubMed

Xu, Yihong; Qiao, Jixin; Hou, Xiaolin; Pan, Shaoming; Roos, Per

2014-02-01

This paper reports an analytical method for the determination of plutonium isotopes ((238)Pu, (239)Pu, (240)Pu, (241)Pu) in environmental samples using anion exchange chromatography in combination with extraction chromatography for chemical separation of Pu. Both radiometric methods (liquid scintillation counting and alpha spectrometry) and inductively coupled plasma mass spectrometry (ICP-MS) were applied for the measurement of plutonium isotopes. The decontamination factors for uranium were significantly improved up to 7.5 × 10(5) for 20 g soil compared to the level reported in the literature, this is critical for the measurement of plutonium isotopes using mass spectrometric technique. Although the chemical yield of Pu in the entire procedure is about 55%, the analytical results of IAEA soil 6 and IAEA-367 in this work are in a good agreement with the values reported in the literature or reference values, revealing that the developed method for plutonium determination in environmental samples is reliable. The measurement results of (239+240)Pu by alpha spectrometry agreed very well with the sum of (239)Pu and (240)Pu measured by ICP-MS. ICP-MS can not only measure (239)Pu and (240)Pu separately but also (241)Pu. However, it is impossible to measure (238)Pu using ICP-MS in environmental samples even a decontamination factor as high as 10(6) for uranium was obtained by chemical separation. © 2013 Elsevier B.V. All rights reserved.

Depth profile of 236U/238U in soil samples in La Palma, Canary Islands

PubMed Central

Srncik, M.; Steier, P.; Wallner, G.

2011-01-01

The vertical distribution of the 236U/238U isotopic ratio was investigated in soil samples from three different locations on La Palma (one of the seven Canary Islands, Spain). Additionally the 240Pu/239Pu atomic ratio, as it is a well establish tool for the source identification, was determined. The radiochemical procedure consisted of a U separation step by extraction chromatography using UTEVA® Resin (Eichrom Technologies, Inc.). Afterwards Pu was separated from Th and Np by anion exchange using Dowex 1x2 (Dow Chemical Co.). Furthermore a new chemical procedure with tandem columns to separate Pu and U from the matrix was tested. For the determination of the uranium and plutonium isotopes by alpha spectrometry thin sources were prepared by microprecipitation techniques. Additionally these fractions separated from the soil samples were measured by Accelerator Mass Spectrometry (AMS) to get information on the isotopic ratios 236U/238U, 240Pu/239Pu and 236U/239Pu, respectively. The 236U concentrations [atoms/g] in each surface layer (∼2 cm) were surprisingly high compared to deeper layers where values around two orders of magnitude smaller were found. Since the isotopic ratio 240Pu/239Pu indicated a global fallout signature we assume the same origin as the probable source for 236U. Our measured 236U/239Pu value of around 0.2 is within the expected range for this contamination source. PMID:21481502

Cs-Ba separation using N 2O as a reactant gas in a Multiple Collector-Inductively Coupled Plasma Mass Spectrometer collision-reaction cell: Application to the measurements of Cs isotopes in spent nuclear fuel samples

NASA Astrophysics Data System (ADS)

Granet, M.; Nonell, A.; Favre, G.; Chartier, F.; Isnard, H.; Moureau, J.; Caussignac, C.; Tran, B.

2008-11-01

In the general frameworks of the nuclear fuel cycle and environmental research field, the Cs isotopic composition must be known with high precision and accuracy. The direct determination of Cs isotopes by mass spectrometry techniques is generally hampered by the presence of Ba isobaric interferences however. Here we present a new method which takes advantage of the collision-reaction cell based Multiple Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICPMS) and allows to analyse Cs isotopes in the presence of Ba without prior separation step. The addition of N 2O gas in the cell leads to an antagonistic behavior of Cs + and Ba + as the latter reacts with the gas to form BaO + and BaOH + products whereas Cs + remains unreactive. The efficiency of the method was demonstrated for an UOx sample by comparing the results obtained (1) from the measurements of pure Cs fractions and (2) from Fission Products fractions containing more than 30 ionisable elements in addition to Cs, Ba, and where U and Pu were previously removed by using ion exchange resin. An excellent agreement is achieved between each set of experiments with an external reproducibility always better than 0.5% (RSD, k = 2). This study confirms the strong potential of collision-reaction cell to measure Cs isotopes in presence of interfering Ba, precluding therefore former systematic chemical separations.

Fast isotopic separation of 10 B and 11 B boric acid by capillary zone electrophoresis.

PubMed

Kamencev, Mikhail; Yakimova, Nina; Moskvin, Leonid; Kuchumova, Irina; Tkach, Kirill; Malinina, Yulia

2016-11-01

Fast isotopic separation of 10 B and 11 B boric acid by CZE was demonstrated. The BGE contained 25 mM phenylalanine and 5 mM putrescine (рН 8.95). The running conditions were +25 kV at 20°C with indirect photometric detection at 210 nm. Baseline separation was achieved in less than 9 min. RSD of migration times and corrected peak areas were less than 0.5 and 3%, respectively (n = 5). Linearity was demonstrated in the range 0.2-2 mM for 11 B and 0.2-0.5 mM for 10 B. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Variants of closing the nuclear fuel cycle

NASA Astrophysics Data System (ADS)

Andrianova, E. A.; Davidenko, V. D.; Tsibulskiy, V. F.; Tsibulskiy, S. V.

2015-12-01

Influence of the nuclear energy structure, the conditions of fuel burnup, and accumulation of new fissile isotopes from the raw isotopes on the main parameters of a closed fuel cycle is considered. The effects of the breeding ratio, the cooling time of the spent fuel in the external fuel cycle, and the separation of the breeding area and the fissile isotope burning area on the parameters of the fuel cycle are analyzed.

Integrated Stable Isotope - Reactive Transport Model Approach for Assessment of Chlorinated Solvent Degradation

DTIC Science & Technology

2016-05-01

Certification Program ETH Ethene GC Gas Chromatography GC-IRMS Gas Chromatography Isotope Ratio Mass Spectroscopy H Hydrogen IRMS Isotope...tool for attenuation of chlorinated solvents. The Demonstration Site was Operable Unit 10 at Hill AFB, Utah , a site where groundwater is impacted...techniques. The method involves extraction of the target compounds from environmental sample matrix, followed by separation of the compounds using gas

Sr isotopic tracer study of the Samail ophiolite, Oman.

USGS Publications Warehouse

Lanphere, M.A.; Coleman, R.G.; Hopson, C.A.

1981-01-01

Rb and Sr concentrations and Sr-isotopic compositions were measured in 41 whole-rock samples and 12 mineral separates from units of the Samail ophiolite, including peridotite, gabbro, plagiogranite, diabase dykes, and gabbro and websterite dykes within the metamorphic peridotite. Ten samples of cumulate gabbro from the Wadir Kadir section and nine samples from the Wadi Khafifah section have 87Sr/86Sr ratios of 0.70314 + or - 0.00030 and 0.70306 + or - 0.00034, respectively. The dispersion in Sr- isotopic composition may reflect real heterogeneities in the magma source region. The average Sr-isotopic composition of cumulate gabbro falls in the range of isotopic compositions of modern MORB. The 87Sr/86Sr ratios of noncumulate gabbro, plagiogranite, and diabase dykes range 0.7034-0.7047, 0.7038-0.7046 and 0.7037- 0.7061, respectively. These higher 87Sr/86Sr ratios are due to alteration of initial magmatic compositions by hydrothermal exchange with sea-water. Mineral separates from dykes that cut harzburgite tectonite have Sr-isotopic compositions which agree with that of cumulate gabbro. These data indicate that the cumulate gabbro and the different dykes were derived from partial melting of source regions that had similar long-term histories and chemical compositions.-T.R.

Ion exchange separation of chromium from natural water matrix for stable isotope mass spectrometric analysis

USGS Publications Warehouse

Ball, J.W.; Bassett, R.L.

2000-01-01

A method has been developed for separating the Cr dissolved in natural water from matrix elements and determination of its stable isotope ratios using solid-source thermal-ionization mass spectrometry (TIMS). The separation method takes advantage of the existence of the oxidized form of Cr as an oxyanion to separate it from interfering cations using anion-exchange chromatography, and of the reduced form of Cr as a positively charged ion to separate it from interfering anions such as sulfate. Subsequent processing of the separated sample eliminates residual organic material for application to a solid source filament. Ratios for 53Cr/52Cr for National Institute of Standards and Technology Standard Reference Material 979 can be measured using the silica gel-boric acid technique with a filament-to-filament standard deviation in the mean 53Cr/52Cr ratio for 50 replicates of 0.00005 or less. (C) 2000 Elsevier Science B.V. All rights reserved.

Method for isotopic analysis of chlorinated organic compounds

DOEpatents

Holt, B.D.; Sturchio, N.C.

1999-08-24

The present invention provides a method for preparing a VOC sample for carbon and chlorine isotope ratio analysis by mass spectrometer. A VOC sample is placed in a combustion tube and reacted with CuO to form CO{sub 2} and CuCl. The CO{sub 2} is then extracted and analyzed for the carbon isotope ratio. The CuCl is separated from the excess CuO and reacted with CH{sub 3}I to form CH{sub 3}Cl, extracted and analyzed for chlorine isotope ratio. 9 figs.

ISOTOPE SEPARATING APPARATUS

DOEpatents

Kudravetz, M.K.; Greene, H.B.

1958-09-16

This patent relates to control systems for a calutron and, in particular, describes an electro-mechanical system for interrupting the collection of charged particles when the ratio between the two isotopes being receivcd deviates from a predetermined value. One embodiment of the invention includes means responsive to the ratio between two isotopes being received for opening a normally closed shutter over the receiver entrance when the isotope ratio is the desired value. In another form of the invention the collection operation is interrupted by changing the beam accelerating voltage to deflect the ion beam away from the receiver.

Environmental Forensics: Using Compound-Specific Stable Carbon Isotope Analysis to Track Petroleum Contamination

NASA Astrophysics Data System (ADS)

Imfeld, A.; Ouellet, A.; Gelinas, Y.

2016-12-01

Crude oil and petroleum products are continually being introduced into the environment during transportation, production, consumption and storage. Source identification of these organic contaminants proves challenging due to a variety of factors; samples tend to be convoluted, compounds need to be separated from an unresolved complex mixtures of highly altered aliphatic and aromatic compounds, and chemical composition and biomarker distributions can be altered by weathering, aging, and degradation processes. The aim of our research is to optimize a molecular and isotopic (δ13C, δ2H) method to fingerprint and identify petroleum contaminants in soil and sediment matrices, and to trace the temporal and spatial extent of the contamination event. This method includes the extraction, separation and analysis of the petroleum derived hydrocarbons. Sample extraction and separation is achieved using sonication, column chromatography and urea adduction. Compound identification and molecular/isotopic fingerprinting is obtained by gas chromatography with flame ionization (GC-FID) and mass spectrometer (GC-MS) detection, as well as gas chromatography coupled to an isotope ratio mass spectrometer (GC-IRMS). This method will be used to assist the Centre d'Expertise en Analyse Environnementale du Québec to determine the nature, sources and timing of contamination events as well as for investigating the residual contamination involving petroleum products.

Process for recovering evolved hydrogen enriched with at least one heavy hydrogen isotope

DOEpatents

Tanaka, John; Reilly, Jr., James J.

1978-01-01

This invention relates to a separation means and method for enriching a hydrogen atmosphere with at least one heavy hydrogen isotope by using a solid titaniun alloy hydride. To this end, the titanium alloy hydride containing at least one metal selected from the group consisting of vanadium, chromium, manganese, molybdenum, iron, cobalt and nickel is contacted with a circulating gaseous flow of hydrogen containing at least one heavy hydrogen isotope at a temperature in the range of -20.degree. to +40.degree. C and at a pressure above the dissociation pressure of the hydrided alloy selectively to concentrate at least one of the isotopes of hydrogen in the hydrided metal alloy. The contacting is continued until equilibrium is reached, and then the gaseous flow is isolated while the temperature and pressure of the enriched hydride remain undisturbed selectively to isolate the hydride. Thereafter, the enriched hydrogen is selectively recovered in accordance with the separation factor (S.F.) of the alloy hydride employed.

Extreme isotopic variations in the upper mantle: evidence from Ronda

NASA Astrophysics Data System (ADS)

Reisberg, Laurie; Zindler, Alan

1986-12-01

The Ronda Ultramafic Complex in southern Spain represents a piece of the Earth's mantle which has been tectonically emplaced into the crust. Nd and Sr isotopic analyses are presented for leached, hand-picked Cr-diopside separates prepared from 15 rock and 18 river sediment samples from Ronda. These results demonstrate that within this small, contiguous body there exists the entire range of Nd isotopic compositions, and much of the range of Sr compositions, found in rocks derived from the sub-oceanic mantle. The sediment cpx samples show that the average isotopic composition of the massif becomes progressively less "depleted" moving from SW to NE along the long axis of the massif. The rock cpx samples document 143Nd/ 144Nd variations from 0.5129 to 0.5126 and 87Sr/ 86Sr variations from 0.7031 to 0.7039 within a uniform outcrop less than 10 m in extent. Thus, extreme isotopic fluctuations exist over a wide range of wavelengths. Sr and Nd isotopes are generally inversely correlated, forming a trend on a Nd-Sr diagram that sharply crosscuts that of the "mantle array". Many of the 143Nd/ 144Nd values, and all of the Sm/Nd values, from one section of the massif are lower than that SCV015SCV0 of the bulk earth, implying that this region existed, or was influenced by a component which existed, in a LREE-enriched environment for a significant period of time. Among the sediment cpxs there is a positive correlation between 143Nd/ 144Nd and 147Sm/ 144Nd. The rock cpx separates display considerably more scatter. A simple, single-stage differentiation event starting with a uniform mantle source cannot explain these results. At least one episode of mixing with a LREE-enriched component is required. If these results from Ronda are typical of the upper mantle, basalts with different isotopic compositions need not derive from spatially separated mantle sources.

Present status of the KISS project

NASA Astrophysics Data System (ADS)

Miyatake, H.; Wada, M.; Watanabe, X. Y.; Hirayama, Y.; Schury, P.; Ahmed, M.; Ishiyama, H.; Jeong, S. C.; Kakiguchi, Y.; Kimura, S.; Moon, J. Y.; Mukai, M.; Oyaizu, M.; Park, J. H.

2018-04-01

KISS project aims at finding an astrophysical condition for synthesizing r-process heavy element isotopes, which are characterized as the third peak in the solar abundance pattern. This is an experimental challenge in nuclear physics to measure ground and isomeric state properties of unknown nuclei around the region of N=126 isotones. So far we have constructed and developed new type of mass separation system, KISS (KEK Isotope Separation System) and performed measurements of lifetimes and hyperfine structures of some platinum and iridium neutron-rich radioactive isotopes by applying multi-nucleon transfer reactions and in-gas laser ionization and spectroscopy (IGLIS) methods. In this report, recent physics results, updated KISS performance, and future's research plan including a challenge of a systematic mass measurement with MRTOF (Multi-Reflection Time-Of-Flight mass spectrograph) are presented.

A comparison of lead-isotope measurements on exploration-type samples using inductively coupled plasma and thermal ionization mass spectrometry

USGS Publications Warehouse

Gulson, B.L.; Meier, A.L.; Church, S.E.; Mizon, K.J.

1989-01-01

Thermal ionization mass spectrometry (TI-MS) has long been the method of choice for Pb-isotope determinations. More recently, however, inductively coupled plasma mass spectrometry (ICP-MS) has been used to determine Pb-isotope ratios for mineral exploration. The ICP-MS technique, although not as precise as TI-MS, may promote a wider application of Ph-isotope ratio methods because it allows individual isotopes to be determined more rapidly, generally without need for chemical separation (e.g., Smith et al., 1984; Hinners et al., 1987). To demonstrate the utility of the ICP-MS method, we have conducted a series of Pb-isotope measurements on several suites of samples using both TI-MS and ICP-MS. ?? 1989.

Separation processes using expulsion from dilute supercritical solutions

DOEpatents

Cochran, Jr., Henry D.

1993-01-01

A process for separating isotopes as well as other mixtures by utilizing the behavior of dilute repulsive or weakly attractive elements of the mixtures as the critical point of the solvent is approached.

Methods for separating medical isotopes using ionic liquids

DOEpatents

Luo, Huimin; Boll, Rose Ann; Bell, Jason Richard; Dai, Sheng

2014-10-21

A method for extracting a radioisotope from an aqueous solution, the method comprising: a) intimately mixing a non-chelating ionic liquid with the aqueous solution to transfer at least a portion of said radioisotope to said non-chelating ionic liquid; and b) separating the non-chelating ionic liquid from the aqueous solution. In preferred embodiments, the method achieves an extraction efficiency of at least 80%, or a separation factor of at least 1.times.10.sup.4 when more than one radioisotope is included in the aqueous solution. In particular embodiments, the method is applied to the separation of medical isotopes pairs, such as Th from Ac (Th-229/Ac-225, Ac-227/Th-227), or Ra from Ac (Ac-225 and Ra-225, Ac-227 and Ra-223), or Ra from Th (Th-227 and Ra-223, Th-229 and Ra-225).

Hydrogen Isotope Measurements of Organic Acids and Alcohols by Pyrolysis-GC-MS-TC-IRMS: Application to Analysis of Experimentally Derived Hydrothermal Mineral-Catalyzed Organic Products

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Fu, Qi; Niles, Paul B.; Gibson, Everett K., Jr.

2012-01-01

We report results of experiments to measure the H isotope composition of organic acids and alcohols. These experiments make use of a pyroprobe interfaced with a GC and high temperature extraction furnace to make quantitative H isotope measurements. This work compliments our previous work that focused on the extraction and analysis of C isotopes from the same compounds [1]. Together with our carbon isotope analyses our experiments serve as a "proof of concept" for making C and H isotope measurements on more complex mixtures of organic compounds on mineral surfaces in abiotic hydrocarbon formation processes at elevated temperatures and pressures. Our motivation for undertaking this work stems from observations of methane detected within the Martian atmosphere [2-5], coupled with evidence showing extensive water-rock interaction during Mars history [6-8]. Methane production on Mars could be the result of synthesis by mineral surface-catalyzed reduction of CO2 and/or CO by Fischer-Tropsch Type (FTT) reactions during serpentization [9,10]. Others have conducted experimental studies to show that FTT reactions are plausible mechanisms for low-molecular weight hydrocarbon formation in hydrothermal systems at mid-ocean ridges [11-13]. Our H isotope measurements utilize an analytical technique combining Pyrolysis-Gas Chromatograph-Mass Spectrometry-High Temperature Conversion-Isotope Ratio Mass Spectrometry (Py-GC-MS-TC-IRMS). This technique is designed to carry a split of the pyrolyzed GC-separated product to a Thermo DSQII quadrupole mass spectrometer as a means of making qualitative and semi-quantitative compositional measurements of separated organic compounds, therefore both chemical and isotopic measurements can be carried out simultaneously on the same sample.

Compound Specific Hydrogen Isotope Composition of Type II and III Kerogen Extracted by Pyrolysis-GC-MS-IRMS

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Pernia, Denet; Evans, Michael; Fu, Qi; Bissada, Kadry K.; Curiale, Joseph A.; Niles, Paul B.

2013-01-01

The use of Hydrogen (H) isotopes in understanding oil and gas resource plays is in its infancy. Described here is a technique for H isotope analysis of organic compounds pyrolyzed from oil and gas shale-derived kerogen. Application of this technique will progress our understanding. This work complements that of Pernia et al. (2013, this meeting) by providing a novel method for the H isotope analysis of specific compounds in the characterization of kerogen extracted by analytically diverse techniques. Hydrogen isotope analyses were carried out entirely "on-line" utilizing a CDS 5000 Pyroprobe connected to a Thermo Trace GC Ultra interfaced with a Thermo MAT 253 IRMS. Also, a split of GC-separated products was sent to a DSQ II quadrupole MS to make semi-quantitative compositional measurements of the extracted compounds. Kerogen samples from five different basins (type II and III) were dehydrated (heated to 80 C overnight in vacuum) and analyzed for their H isotope compositions by Pyrolysis-GC-MS-TC-IRMS. This technique takes pyrolysis products separated via GC and reacts them in a high temperature conversion furnace (1450 C) which quantitatively forms H2, following a modified method of Burgoyne and Hayes, (1998, Anal. Chem., 70, 5136-5141). Samples ranging from approximately 0.5 to 1.0mg in size, were pyrolyzed at 800 C for 30s. Compounds were separated on a Poraplot Q GC column. Hydrogen isotope data from all kerogen samples typically show enrichment in D from low to high molecular weight compounds. Water (H2O) average deltaD = -215.2 (V-SMOW), ranging from -271.8 for the Marcellus Shale to -51.9 for the Polish Shale. Higher molecular weight compounds like toluene (C7H8) have an average deltaD of -89.7 0/00, ranging from -156.0 for the Barnett Shale to -50.0 for the Monterey Shale. We interpret these data as representative of potential H isotope exchange between hydrocarbons and sediment pore water during formation within each basin. Since hydrocarbon H isotopes readily exchange with water, these data may provide some useful information on gas-water or oil-water interaction in resource plays, and further as a possible indicator of paleo-environmental conditions. Alternatively, our data may be an indication of H isotope exchange with water and/or acid during the kerogen isolation process. Either of these interpretations will prove useful when deciphering H isotope data derived from kerogen analysis. More experiments are planned to discern these two or other possible scenarios.

Testing sequential extraction methods for the analysis of multiple stable isotope systems from a bone sample

NASA Astrophysics Data System (ADS)

Sahlstedt, Elina; Arppe, Laura

2017-04-01

Stable isotope composition of bones, analysed either from the mineral phase (hydroxyapatite) or from the organic phase (mainly collagen) carry important climatological and ecological information and are therefore widely used in paleontological and archaeological research. For the analysis of the stable isotope compositions, both of the phases, hydroxyapatite and collagen, have their more or less well established separation and analytical techniques. Recent development in IRMS and wet chemical extraction methods have facilitated the analysis of very small bone fractions (500 μg or less starting material) for PO43-O isotope composition. However, the uniqueness and (pre-) historical value of each archaeological and paleontological finding lead to preciously little material available for stable isotope analyses, encouraging further development of microanalytical methods for the use of stable isotope analyses. Here we present the first results in developing extraction methods for combining collagen C- and N-isotope analyses to PO43-O-isotope analyses from a single bone sample fraction. We tested sequential extraction starting with dilute acid demineralization and collection of both collagen and PO43-fractions, followed by further purification step by H2O2 (PO43-fraction). First results show that bone sample separates as small as 2 mg may be analysed for their δ15N, δ13C and δ18OPO4 values. The method may be incorporated in detailed investigation of sequentially developing skeletal material such as teeth, potentially allowing for the investigation of interannual variability in climatological/environmental signals or investigation of the early life history of an individual.

Empirical calibration of the clinopyroxene-garnet magnesium isotope geothermometer and implications

NASA Astrophysics Data System (ADS)

Li, Wang-Ye; Teng, Fang-Zhen; Xiao, Yilin; Gu, Hai-Ou; Zha, Xiang-Ping; Huang, Jian

2016-07-01

The large equilibrium Mg isotope fractionation between clinopyroxene and garnet observed in eclogites makes it a potential high-precision geothermometer, but calibration of this thermometer by natural samples is still limited. Here, we report Mg isotopic compositions of eclogite whole rocks as well as Mg and O isotopic compositions of clinopyroxene and garnet separates from 16 eclogites that formed at different temperatures from the Dabie orogen, China. The whole-rock δ26Mg values vary from -1.20 to +0.10 ‰. Among them, 11 samples display limited δ26Mg variations from -0.36 to -0.17 ‰, similar to those of their protoliths. The mineral separates exhibit very different δ26Mg values, from -0.39 to +0.39 ‰ for clinopyroxenes and from -1.94 to -0.81 ‰ for garnets. The clinopyroxene-garnet Mg isotope fractionation (Δ26Mgclinopyroxene-garnet = δ26Mgclinopyroxene-δ26Mggarnet) varies from 1.05 to 2.15 ‰. The clinopyroxene-garnet O isotope fractionation (Δ18Oclinopyroxene-garnet = δ18Oclinopyroxene-δ18Ogarnet) varies from -1.01 to +0.98 ‰. Equilibrium Mg isotope fractionation between clinopyroxene and garnet in the investigated samples is selected based on both the δ26Mgclinopyroxene versus δ26Mggarnet plot and the state of O isotope equilibrium between clinopyroxene and garnet. The equilibrium Δ26Mgclinopyroxene-garnet and corresponding temperature data obtained in this study, together with those available so far in literatures for natural eclogites, are used to calibrate the clinopyroxene-garnet Mg isotope thermometer. This yields a function of Δ26Mgclinopyroxene-garnet = (0.99 ± 0.06) × 106/ T 2, where T is temperature in Kelvin. The refined function not only provides the best empirically calibrated clinopyroxene-garnet Mg isotope thermometer for precise constraints of temperatures of clinopyroxene- and garnet-bearing rocks, but also has potential applications in high-temperature Mg isotope geochemistry.

A simple distillation method to extract bromine from natural water and salt samples for isotope analysis by multi-collector inductively coupled plasma mass spectrometry.

PubMed

Eggenkamp, H G M; Louvat, P

2018-04-30

In natural samples bromine is present in trace amounts, and measurement of stable Br isotopes necessitates its separation from the matrix. Most methods described previously need large samples or samples with high Br/Cl ratios. The use of metals as reagents, proposed in previous Br distillation methods, must be avoided for multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) analyses, because of risk of cross-contamination, since the instrument is also used to measure stable isotopes of metals. Dedicated to water and evaporite samples with low Br/Cl ratios, the proposed method is a simple distillation that separates bromide from chloride for isotopic analyses by MC-ICP-MS. It is based on the difference in oxidation potential between chloride and bromide in the presence of nitric acid. The sample is mixed with dilute (1:5) nitric acid in a distillation flask and heated over a candle flame for 10 min. The distillate (bromine) is trapped in an ammonia solution and reduced to bromide. Chloride is only distilled to a very small extent. The obtained solution can be measured directly by MC-ICP-MS for stable Br isotopes. The method was tested for a variety of volumes, ammonia concentrations, pH values and distillation times and compared with the classic ion-exchange chromatography method. The method more efficiently separates Br from Cl, so that samples with lower Br/Cl ratios can be analysed, with Br isotope data in agreement with those obtained by previous methods. Unlike other Br extraction methods based on oxidation, the distillation method presented here does not use any metallic ion for redox reactions that could contaminate the mass spectrometer. It is efficient in separating Br from samples with low Br/Cl ratios. The method ensures reproducible recovery yields and a long-term reproducibility of ±0.11‰ (1 standard deviation). The distillation method was successfully applied to samples with low Br/Cl ratios and low Br amounts (down to 20 μg). Copyright © 2018 John Wiley & Sons, Ltd.

Process for radioisotope recovery and system for implementing same

DOEpatents

Meikrantz, David H [Idaho Falls, ID; Todd, Terry A [Aberdeen, ID; Tranter, Troy J [Idaho Falls, ID; Horwitz, E Philip [Naperville, IL

2009-10-06

A method of recovering daughter isotopes from a radioisotope mixture. The method comprises providing a radioisotope mixture solution comprising at least one parent isotope. The at least one parent isotope is extracted into an organic phase, which comprises an extractant and a solvent. The organic phase is substantially continuously contacted with an aqueous phase to extract at least one daughter isotope into the aqueous phase. The aqueous phase is separated from the organic phase, such as by using an annular centrifugal contactor. The at least one daughter isotope is purified from the aqueous phase, such as by ion exchange chromatography or extraction chromatography. The at least one daughter isotope may include actinium-225, radium-225, bismuth-213, or mixtures thereof. A liquid-liquid extraction system for recovering at least one daughter isotope from a source material is also disclosed.

Process for radioisotope recovery and system for implementing same

DOEpatents

Meikrantz, David H.; Todd, Terry A.; Tranter, Troy J.; Horwitz, E. Philip

2007-01-02

A method of recovering daughter isotopes from a radioisotope mixture. The method comprises providing a radioisotope mixture solution comprising at least one parent isotope. The at least one parent isotope is extracted into an organic phase, which comprises an extractant and a solvent. The organic phase is substantially continuously contacted with an aqueous phase to extract at least one daughter isotope into the aqueous phase. The aqueous phase is separated from the organic phase, such as by using an annular centrifugal contactor. The at least one daughter isotope is purified from the aqueous phase, such as by ion exchange chromatography or extraction chromatography. The at least one daughter isotope may include actinium-225, radium-225, bismuth-213, or mixtures thereof. A liquid-liquid extraction system for recovering at least one daughter isotope from a source material is also disclosed.

Modified ion exchange separation for tungsten isotopic measurements from kimberlite samples using multi-collector inductively coupled plasma mass spectrometry.

PubMed

Sahoo, Yu Vin; Nakai, Shun'ichi; Ali, Arshad

2006-03-01

Tungsten isotope composition of a sample of deep-seated rock can record the influence of core-mantle interaction of the parent magma. Samples of kimberlite, which is known as a carrier of diamond, from the deep mantle might exhibit effects of core-mantle interaction. Although tungsten isotope anomaly was reported for kimberlites from South Africa, a subsequent investigation did not verify the anomaly. The magnesium-rich and calcium-rich chemical composition of kimberlite might engender difficulty during chemical separation of tungsten for isotope analyses. This paper presents a simple, one-step anion exchange technique for precise and accurate determination of tungsten isotopes in kimberlites using multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). Large quantities of Ca and Mg in kimberlite samples were precipitated and removed with aqueous H(2)SO(4). Highly pure fractions of tungsten for isotopic measurements were obtained following an anion exchange chromatographic procedure involving mixed acids. That procedure enabled efficient removal of high field strength elements (HFSE), such as Hf, Zr and Ti, which are small ions that carry strong charges and develop intense electrostatic fields. The tungsten yields were 85%-95%. Advantages of this system include less time and less use of reagents. Precise and accurate isotopic measurements are possible using fractions of tungsten that are obtained using this method. The accuracy and precision of these measurements were confirmed using various silicate standard rock samples, JB-2, JB-3 and AGV-1.

Precise Analysis of Gallium Isotopic Composition by MC-ICP-MS.

PubMed

Yuan, Wei; Chen, Jiu Bin; Birck, Jean-Louis; Yin, Zuo Ying; Yuan, Sheng Liu; Cai, Hong Ming; Wang, Zhong Wei; Huang, Qiang; Wang, Zhu Hong

2016-10-04

Though an isotope approach could be beneficial for better understanding the biogeochemical cycle of gallium (Ga), an analogue of the monoisotopic element aluminum (Al), the geochemistry of Ga isotopes has not been widely elaborated. We developed a two-step method for purifying Ga from geological (biological) samples for precise measurement of Ga isotope ratio using multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS). Ga was thoroughly separated from other matrix elements using two chromatographic columns loaded with AG 1-X4 and Ln-spec resin, respectively. The separation method was carefully calibrated using both synthetic and natural samples and validated by assessing the extraction yield (99.8 ± 0.8%, 2SD, n = 23) and the reproducibility (2SD uncertainty better than 0.05‰, n = 116) of the measured isotopic ratio (expressed as δ 71 Ga). The validation of the whole protocol, together with instrumental analysis, was confirmed by the investigation of the matrix effect, the result of a standard addition experiment, and the comparison of Ga isotope measurement on two mass spectrometers-Nu Plasma II and Neptune Plus. Although the measurements using the sample-standard bracketing (SSB) correction method on both instruments resulted in identical δ 71 Ga values for reference materials, the modified empirical external normalization (MEEN) method gave relatively better precision compared to SSB on Neptune. Our preliminary results showed large variation of δ 71 Ga (up to 1.83‰) for 10 standards, with higher values in industrially produced materials, implying potential application of Ga isotopes.

Separation processes using expulsion from dilute supercritical solutions

DOEpatents

Cochran, H.D. Jr.

1993-04-20

A process is described for separating isotopes as well as other mixtures by utilizing the behavior of dilute repulsive or weakly attractive elements of the mixtures as the critical point of the solvent is approached.

Detection of Synthetic Testosterone Use by Novel Comprehensive Two-Dimensional Gas Chromatography Combustion Isotope Ratio Mass Spectrometry (GC×GCC-IRMS)

PubMed Central

Tobias, Herbert J.; Zhang, Ying; Auchus, Richard J.; Brenna, J. Thomas

2011-01-01

We report the first demonstration of Comprehensive Two-dimensional Gas Chromatography Combustion Isotope Ratio Mass Spectrometry (GC×GCC-IRMS) for the analysis of urinary steroids to detect illicit synthetic testosterone use, of interest in sport doping. GC coupled to IRMS (GCC-IRMS) is currently used to measure the carbon isotope ratios (CIR, δ13C) of urinary steroids in anti-doping efforts; however, extensive cleanup of urine extracts is required prior to analysis to enable baseline separation of target steroids. With its greater separation capabilities, GC×GC has the potential to reduce sample preparation requirements and enable CIR analysis of minimally processed urine extracts. Challenges addressed include on-line reactors with minimized dimensions to retain narrow peaks shapes, baseline separation of peaks in some cases, and reconstruction of isotopic information from sliced steroid chromatographic peaks. Difficulties remaining include long-term robustness of on-line reactors and urine matrix effects that preclude baseline separation and isotopic analysis of low concentration and trace components. In this work, steroids were extracted, acetylated, and analyzed using a refined, home-built GC×GCC-IRMS system. 11-hydroxy-androsterone (11OHA) and 11-ketoetiocolanolone (11KE) were chosen as endogenous reference compounds (ERC) because of their satisfactory signal intensity, and their CIR was compared to target compounds (TC) androsterone (A) and etiocholanolone (E). Separately, a GC×GC-qMS system was used to measure testosterone (T)/EpiT concentration ratios. Urinary extracts of urine pooled from professional athletes, and urine from one individual that received testosterone gel (T-gel) and one individual that received testosterone injections (T-shot) were analyzed. The average precisions of δ13C and Δδ13C measurements were SD(δ13C) approximately ± 1‰ (n=11). The T-shot sample resulted in a positive for T use with a T/EpiT ratio of > 9 and CIR measurements of Δδ13C > 5‰, both fulfilling World Anti-Doping Agency criteria. These data show for the first time that synthetic steroid use is detectable by GC×GCC-IRMS without need for extensive urine cleanup. PMID:21846122

Evaluation of carbon isotope flux partitioning theory under simplified and controlled environmental conditions

USDA-ARS?s Scientific Manuscript database

Separation of the photosynthetic (Fp) and respiratory (Fr) fluxes of net CO2 exchange (Fn)remains a necessary step toward understanding the biological and physical controls on carbon cycling between the soil, biomass, and atmosphere. Despite recent advancements in stable carbon isotope partitioning ...

Microscopic model for the isotope effect in the high-Tc oxides

NASA Astrophysics Data System (ADS)

Kresin, V. Z.; Wolf, S. A.

1994-02-01

An unconventional microscopic mechanism relating Tc and the isotope substitution for the doped superconductors such as the high-Tc oxides is proposed. Strong nonadiabaticity, when it is impossible, strictly speaking, to separate fully the nuclear and electronic degrees of freedom, leads to a peculiar dependence of the carrier concentration n on the ionic mass M. This case corresponds, for example, to the isotopic substitution of the axial oxygen in YBa2Cu3O7-x. Because of the dependence of Tc on n, this leads to the dependence of Tc on M, that is to the isotope effect. The minimum value of the isotope coefficient corresponds to Tc=Tmaxc.

Precision mass measurements of neutron-rich Co isotopes beyond N =40

NASA Astrophysics Data System (ADS)

Izzo, C.; Bollen, G.; Brodeur, M.; Eibach, M.; Gulyuz, K.; Holt, J. D.; Kelly, J. M.; Redshaw, M.; Ringle, R.; Sandler, R.; Schwarz, S.; Stroberg, S. R.; Sumithrarachchi, C. S.; Valverde, A. A.; Villari, A. C. C.

2018-01-01

The region near Z =28 and N =40 is a subject of great interest for nuclear structure studies due to spectroscopic signatures in 68Ni suggesting a subshell closure at N =40 . Trends in nuclear masses and their derivatives provide a complementary approach to shell structure investigations via separation energies. Penning trap mass spectrometry has provided precise measurements for a number of nuclei in this region; however, a complete picture of the mass surfaces has so far been limited by the large uncertainty remaining for nuclei with N >40 along the iron (Z =26 ) and cobalt (Z =27 ) chains because these species are not available from traditional isotope separator online rare isotope facilities. The Low-Energy Beam and Ion Trap Facility at the National Superconducting Cyclotron Laboratory is the first and only Penning trap mass spectrometer coupled to a fragmentation facility and therefore presents the unique opportunity to perform precise mass measurements of these elusive isotopes. Here we present the first Penning trap measurements of Co,6968, carried out at this facility. Some ambiguity remains as to whether the measured values are ground-state or isomeric-state masses. A detailed discussion is presented to evaluate this question and to motivate future work. In addition, we perform ab initio calculations of ground-state and two-neutron separation energies of cobalt isotopes with the valence-space in-medium similarity renormalization group approach based on a particular set of two- and three-nucleon forces that predict saturation in infinite matter. We discuss the importance of these measurements and calculations for understanding the evolution of nuclear structure near 68Ni.

Hafnium isotope stratigraphy of ferromanganese crusts

PubMed

Lee; Halliday; Hein; Burton; Christensen; Gunther

1999-08-13

A Cenozoic record of hafnium isotopic compositions of central Pacific deep water has been obtained from two ferromanganese crusts. The crusts are separated by more than 3000 kilometers but display similar secular variations. Significant fluctuations in hafnium isotopic composition occurred in the Eocene and Oligocene, possibly related to direct advection from the Indian and Atlantic oceans. Hafnium isotopic compositions have remained approximately uniform for the past 20 million years, probably reflecting increased isolation of the central Pacific. The mechanisms responsible for the increase in (87)Sr/(86)Sr in seawater through the Cenozoic apparently had no effect on central Pacific deep-water hafnium.

Measurement of stable isotopic enrichment and concentration of long-chain fatty acyl-carnitines in tissue by HPLC-MS.

PubMed

Sun, Dayong; Cree, Melanie G; Zhang, Xiao-Jun; Bøersheim, Elisabet; Wolfe, Robert R

2006-02-01

We have developed a new method for the simultaneous measurements of stable isotopic tracer enrichments and concentrations of individual long-chain fatty acyl-carnitines in muscle tissue using ion-pairing high-performance liquid chromatography-electrospray ionization quadrupole mass spectrometry in the selected ion monitoring (SIM) mode. Long-chain fatty acyl-carnitines were extracted from frozen muscle tissue samples by acetonitrile/methanol. Baseline separation was achieved by reverse-phase HPLC in the presence of the volatile ion-pairing reagent heptafluorobutyric acid. The SIM capability of a single quadrupole mass analyzer allows further separation of the ions of interest from the sample matrixes, providing very clean total and selected ion chromatograms that can be used to calculate the stable isotopic tracer enrichment and concentration of long-chain fatty acyl-carnitines in a single analysis. The combination of these two separation techniques greatly simplifies the sample preparation procedure and increases the detection sensitivity. Applying this protocol to biological muscle samples proves it to be a very sensitive, accurate, and precise analytical tool.

Uncoupling between soil and xylem water isotopic composition: how to discriminate mobile and tightly-bound water?

NASA Astrophysics Data System (ADS)

Martín Gómez, Paula; Aguilera, Mònica; Pemán, Jesús; Gil Pelegrín, Eustaquio; Ferrio, Juan Pedro

2014-05-01

As a general rule, no isotopic fractionation occurs during water uptake and water transport, thus, xylem water reflects source water. However, this correspondence does not always happen. Isotopic enrichment of xylem water has been found in several cases and has been either associated to 'stem processes' like cuticular evaporation 1 and xylem-phloem communication under water stress 2,3 or to 'soil processes' such as species-specific use of contrasting water sources retained at different water potential forces in soil. In this regard, it has been demonstrated that mobile and tightly-bound water may show different isotopic signature 4,5. However, standard cryogenic distillation does not allow to separate different water pools within soil samples. Here, we carried out a study in a mixed adult forest (Pinus sylvestris, Quercus subpyrenaica and Buxus sempervirens) growing in a relatively deep loamy soil in the Pre-Pyrenees. During one year, we sampled xylem from twigs and soil at different depths (10, 30 and 50 cm). We also sampled xylem from trunk and bigger branches to assess whether xylem water was enriched in the distal parts of the tree. We found average deviations in the isotopic signature from xylem to soil of 4o 2o and 2.4o in δ18O and 18.3o 7.3o and 8.9o in δ2H, for P.sylvestris, Q.subpyrenaica and B.sempervirens respectively. Xylem water was always enriched compared to soil. In contrast, we did not find clear differences in isotopic composition between xylem samples along the tree. Declining the hypothesis that 'stem processes' would cause these uncoupling between soil and xylem isotopic values, we tested the possibility to separate mobile and tightly-bound water by centrifugation. Even though we could separate two water fractions in soils close to saturation, we could not recover a mobile fraction in drier soils. In this regard, we welcome suggestions on alternatives to separate different soil fractions in order to find the correspondence between soil and xylem water. References 1. Dawson, T. E. & Ehleringer, J. R. Isotopic enrichment of water in the 'woody' tissues of plants: Implications for plant water source, water uptake, and other studies which use the stable isotopic composition of cellulose. (1993). 2. Cernusak, L. a, Farquhar, G. D. & Pate, J. S. Environmental and physiological controls over oxygen and carbon isotope composition of Tasmanian blue gum, Eucalyptus globulus. Tree Physiol. 25, 129-46 (2005). 3. Bertrand, G. et al. Determination of spatiotemporal variability of tree water uptake using stable isotopes (δ 18 O, δ 2 H) in an alluvial system supplied by a high-altitude watershed, Pfyn forest, Switzerland. Ecohydrology (2012). doi:10.1002/eco.1347 4. Tang, K. & Feng, X. The effect of soil hydrology on the oxygen and hydrogen isotopic compositions of plants ' source water. 185, (2001). 5. Brooks, J. R., Barnard, H. R., Coulombe, R. & McDonnell, J. J. Ecohydrologic separation of water between trees and streams in a Mediterranean climate. Nat. Geosci. 3, 100-104 (2009). Acknowledgements This study was funded by RESILFOR project (AGL 2012-40039-C02-02) and FPU fellowship from the Spanish Ministry of Science and Innovation (FPU12/00648). We thank Instituto de Formación Agroambiental de Jaca and Unidad de Salud de los Bosques de Aragón for their support on field work and we feel very grateful to Miguel Ángel Lázaro for climbing the studied trees, José María Alcaire for one year of rain collection and Pilar Sopeña and Ma Josep Pau for laboratory analysis. Helpful comments by Jordi Voltas on statistical analysis have improved the quality of the work.

CALUTRON RECEIVER

DOEpatents

Barnes, S.W.

1959-08-25

An improvement in a calutron receiver for collecting the isotopes ts described. The electromagnetic separation of the isotopes produces a mass spectrum of closely adjacent beams of ions at the foci regions, and a dividing wall between the two pockets is arranged at an angle. Substantially all of the tons of the less abundant isotope enter one of the pockets and strike one side of the wall directly, while substantially none of the tons entering the other pocket strikes the wall directly.

In-Gel Stable-Isotope Labeling (ISIL): a strategy for mass spectrometry-based relative quantification.

PubMed

Asara, John M; Zhang, Xiang; Zheng, Bin; Christofk, Heather H; Wu, Ning; Cantley, Lewis C

2006-01-01

Most proteomics approaches for relative quantification of protein expression use a combination of stable-isotope labeling and mass spectrometry. Traditionally, researchers have used difference gel electrophoresis (DIGE) from stained 1D and 2D gels for relative quantification. While differences in protein staining intensity can often be visualized, abundant proteins can obscure less abundant proteins, and quantification of post-translational modifications is difficult. A method is presented for quantifying changes in the abundance of a specific protein or changes in specific modifications of a protein using In-gel Stable-Isotope Labeling (ISIL). Proteins extracted from any source (tissue, cell line, immunoprecipitate, etc.), treated under two experimental conditions, are resolved in separate lanes by gel electrophoresis. The regions of interest (visualized by staining) are reacted separately with light versus heavy isotope-labeled reagents, and the gel slices are then mixed and digested with proteases. The resulting peptides are then analyzed by LC-MS to determine relative abundance of light/heavy isotope pairs and analyzed by LC-MS/MS for identification of sequence and modifications. The strategy compares well with other relative quantification strategies, and in silico calculations reveal its effectiveness as a global relative quantification strategy. An advantage of ISIL is that visualization of gel differences can be used as a first quantification step followed by accurate and sensitive protein level stable-isotope labeling and mass spectrometry-based relative quantification.

CENTRIFUGE APPARATUS

DOEpatents

Skarstrom, C.; Urey, H.C.; Cohen, K.

1960-08-01

A high-speed centrifuge for the separation of gaseous isotopes is designed comprising a centrifugal pump mounted on the outlet of a centrifuge bowl and arranged to pump the heavy and light fractions out of the centrifuge bowl in two separate streams.

Modelling aspects regarding the control in 13C isotope separation column

NASA Astrophysics Data System (ADS)

Boca, M. L.

2016-08-01

Carbon represents the fourth most abundant chemical element in the world, having two stable and one radioactive isotope. The 13Carbon isotopes, with a natural abundance of 1.1%, plays an important role in numerous applications, such as the study of human metabolism changes, molecular structure studies, non-invasive respiratory tests, Alzheimer tests, air pollution and global warming effects on plants [9] A manufacturing control system manages the internal logistics in a production system and determines the routings of product instances, the assignment of workers and components, the starting of the processes on not-yet-finished product instances. Manufacturing control does not control the manufacturing processes themselves, but has to cope with the consequences of the processing results (e.g. the routing of products to a repair station). In this research it was fulfilled some UML (Unified Modelling Language) diagrams for modelling the C13 Isotope Separation column, implement in STARUML program. Being a critical process and needing a good control and supervising, the critical parameters in the column, temperature and pressure was control using some PLC (Programmable logic controller) and it was made some graphic analyze for this to observe some critical situation than can affect the separation process. The main parameters that need to be control are: -The liquid nitrogen (N2) level in the condenser. -The electrical power supplied to the boiler. -The vacuum pressure.

PALOMA : an isotope analyzer using static mass spectrometry, coupled with cryogenic and chemical trapping, for the MSL mission to Mars

NASA Astrophysics Data System (ADS)

Chassefiere, E.; Jambon, A.; Berthelier, J.-J.; Goulpeau, G.; Leblanc, F.; Montmessin, F.; Sarda, P.; Agrinier, P.; Fouchet, T.; Waite, H.

The technique of GCMS analysis has to be completed by static mass spectrometry for precise in-situ measurements of the isotopic composition of planetary atmospheres (noble gases, stable isotopes), and volatile outgassed products from solid sample pyrolysis. Static mass spectrometry, coupled with gas separation by cryo-separation and gettering, is commonly used in the laboratory to study volatiles extracted from terrestrial and meteoritic samples. Such an instrument (PALOMA) is presently developed in our laboratories, and it will be coupled with a Pyr-GCMS analyzer (MACE), built by a US consortium of science laboratories and industrials (University of Michigan, Southwest Research Institute, JPL, Ball Aerospace). The MACE/PALOMA experiment will be proposed on the NASA Mars Science Laboratory mission, planned to be launched in 2009. The scientific objectives of PALOMA, coupled with MACE, may be listed as follows : (i) search for isotopic signatures of past life in atmosphere, rock, dust and ice samples, with emphasis on carbon, nitrogen and hydrogen; (ii) accurately measure isotopic composition of atmospheric noble gases, and stable isotopes, in order to better constrain past escape, surface interaction, outgassing history and climate evolution; (iii) precisely measure diurnal/ seasonal variations of isotopic ratios of H2O, CO2, and N2, for improving our understanding of present and past climate, and of the role of water cycle. Main measurement objectives are : (i) C, H, O, N isotopic composition in both organic evolved samples (provided by MACE pyrolysis system) and atmosphere with high accuracy (a few per mil at 1-s level); (ii) noble gas (He, Ne, Ar, Kr, Xe) and stable (C, H, O, N) isotope composition in atmosphere with high accuracy (a few per mil at 1-s level); (iii) molecular and isotopic composition of inorganic evolved samples (salts, hydrates, nitrates, {ldots}), including ices; (iv) diurnal and seasonal monitoring of D/H in water vapor, and water ice.

Hydrogen (H) Isotope Composition of Type II Kerogen Extracted by Pyrolysis-GC-MS-IRMS: Terrestrial Shale Deposits as Martian Analogs

NASA Technical Reports Server (NTRS)

Socki, Richard A.; Pernia, Denet; Evans, Michael; Fu, Qi; Bissada, Kadry K.; Curiale, Joseph A.; Niles, Paul B.

2014-01-01

Described here is a technique for H isotope analysis of organic compounds pyrolyzed from kerogens isolated from gas- and liquids-rich shales. Application of this technique will progress the understanding of the use of H isotopes not only in potential kerogen occurrences on Mars, but also in terrestrial oil and gas resource plays. H isotope extraction and analyses were carried out utilizing a CDS 5000 Pyroprobe connected to a Thermo Trace GC interfaced with a Thermo MAT 253 IRMS. Also, a split of GC-separated products was sent to a DSQ II quadrupole MS to make qualitative and semi-quantitative compositional measurements of these products. Kerogen samples from five different basins (type II and II-S) were dehydrated (heated to 80 C overnight under vacuum) and analyzed for their H isotope compositions by Pyrolysis-GC-MS-TC-IRMS. This technique takes pyrolysis products separated via GC and reacts them in a high temperature conversion furnace (1450 C), which quantitatively forms H2. Samples ranging from 0.5 to 1.0mg in size, were pyrolyzed at 800 C for 30s. and separated on a Poraplot Q GC column. H isotope data from all kerogen samples typically show enrichment in D from low to high molecular weight. H2O average delta D = -215.2 per mille (V-SMOW), ranging from - 271.8 per mille for the Marcellus Shale to -51.9 per mille for a Polish shale. Higher molecular weight compounds like toluene (C7H8) have an average delta D of -89.7 per mille, ranging from -156.0 per mille for the Barnett Shale to -50.0 per mille for the Monterey Shale. We interpret these data as representative of potential H isotope exchange between hydrocarbons and sediment pore water during basin formation. Since hydrocarbon H isotopes readily exchange with water, these data may provide some useful information on gas-water or oil-water interaction in resource plays, and further as a possible indicator of paleoenvironmental conditions. Alternatively, our data may be an indication of H isotope exchange with water and/or acid during the kerogen isolation process. Either of these interpretations will prove useful when deciphering H isotope data derived from kerogen analyses. Understanding the role that these H-bearing compounds play in terrestrial shale paleo-environmental reconstruction may also prove useful as analogs for understanding the interactions of water and potential kerogen/organic compounds on the planet Mars.

Molten Salts and Isotope Separation

NASA Astrophysics Data System (ADS)

Lantelme, Frédéric

2013-02-01

The work on molten salts and isotope separation performed over the years at Université Pierre et Marie Curie and at Collège de France is critically reviewed. This research, closely related to A. Klemm's pioneering contributions, leads among other things to the discovery of the effect now called the `Chemla effect', after the late Professor Marius Chemla. These studies of ionic motions in melts, and liquids in general, have greatly benefitted from recent advances in molecular simulations. Some recent results of such simulations - molecular dynamics (MD) and Brownian dynamics (BD) - as well as of related theoretical work are discussed.

Constraints on the origin of Os-isotope disequilibrium in included and interstitial sulfides in mantle peridotites: Implications for the interpretation of Os-isotope signatures in MORB and Abyssal Peridotites

NASA Astrophysics Data System (ADS)

Lassiter, J. C.

2016-12-01

The use of isotope variations in basalts to probe the composition and evolution of the mantle is predicated on the assumption of local (i.e., grain-scale) isotopic equilibrium during mantle melting (Hofmann & Hart, 1978). However, several studies report Os-isotope disequilibrium in distinct populations of sulfides in some peridotites. In principle, grain-scale isotopic heterogeneity could reflect variable radiogenic ingrowth in ancient sulfides with variable Re/Os, or partial re-equilibration of low-Re/Os sulfides with high-Re/Os silicate phases along grain boundaries during mantle melting (e.g., Alard et al., 2005). Both cases require that sulfides fail to maintain isotopic equilibrium with neighboring phases over geologically long ( Ga) time scales. The preservation of Os-isotope disequilibrium in peridotites has been ascribed to the armoring effect of low-[Os] silicates, which limit diffusive exchange between isolated Os-rich phases. This raises the prospect that peridotite-derived melts may not inherit the Os-isotope composition of their source. The timescale required for diffusive equilibration between separate sulfide grains or between Os-rich sulfides and Os-poor silicates is a function of average sulfide size and spacing, Os diffusivity in armoring silicate minerals, and Os partitioning between silicate and sulfide phases. For typical sulfide abundances and sizes in mantle peridotites, neighboring sulfides are expected to re-equilibrate in less than a few 10s of m.y. at adiabatic mantle temperatures, even for very high (>106) sulfide/silicate KD values. Maintenance of disequilibrium requires very large sulfides (>100 um) separated by several mm and diffusion rates (D < 10-20 m2/s) slower than for most other elements in olivine. Equilibration timescales between sulfides and surrounding silicates are similar, so that large-scale isotopic disequilibrium between sulfides and silicates is also unlikely within the convecting mantle. Instead, observed grain-scale Os-isotope disequilibrium in mantle peridotites likely reflects recent sulfide metasomatism linked to interaction with eclogite- or pyroxenite-derived melts. Interstitial sulfides with radiogenic Os-isotopes provide further evidence for a role of eclogite melting in MORB genesis.

Compound-specific nitrogen isotope analysis of D-alanine, L-alanine, and valine: application of diastereomer separation to delta15N and microbial peptidoglycan studies.

PubMed

Takano, Yoshinori; Chikaraishi, Yoshito; Ogawa, Nanako O; Kitazato, Hiroshi; Ohkouchi, Naohiko

2009-01-01

We have developed an analytical method to determine the compound-specific nitrogen isotope compositions of individual amino acid enantiomers using gas chromatography/combustion/isotope ratio mass spectrometry. A novel derivatization of amino acid diastereomers by optically active (R)-(-)-2-butanol or (S)-(+)-2-butanol offers two advantages for nitrogen isotope analysis. First, chromatographic chiral separation can be achieved without the use of chiral stationary-phase columns. Second, the elution order of these compounds on the chromatogram can be switched by a designated esterification reaction. We applied the method to the compound-specific nitrogen isotope analysis of D- and L-alanine in a peptidoglycan derived from the cell walls of cultured bacteria (Firmicutes and Actinobacteria; Enterococcus faecalis, Staphylococcus aureus, Staphylococcus staphylolyticus, Lactobacillus acidophilus, Bacillus subtilis, Micrococcus luteus, and Streptomyces sp.), natural whole bacterial cells (Bacillus subtilis var. natto), (pseudo)-peptidoglycan from archaea (Methanobacterium sp.), and cell wall from eukaryota (Saccharomyces cerevisiae). We observed statistically significant differences in nitrogen isotopic compositions; e.g., delta15N ( per thousand vs air) in Staphylococcus staphylolyticus for d-alanine (19.2 +/- 0.5 per thousand, n = 4) and L-alanine (21.3 +/- 0.8 per thousand, n = 4) and in Bacillus subtilis for D-alanine (6.2 +/- 0.2 per thousand, n = 3) and L-alanine (8.2 +/- 0.4 per thousand, n = 3). These results suggest that enzymatic reaction pathways, including the alanine racemase reaction, produce a nitrogen isotopic difference in amino acid enantiomers, resulting in 15N-depleted D-alanine. This method is expected to facilitate compound-specific nitrogen isotope studies of amino acid stereoisomers.

Photonuclear Production of Medical Isotopes

NASA Astrophysics Data System (ADS)

Weinandt, Nick

2011-10-01

Every year, more than 20 million people in the United States receive a nuclear medicine procedure. Many of the isotopes needed for these procedures are under-produced. Suppliers of the isotopes are usually located outside the United States, which presents a problem when the desired isotopes have short half-lives. Linear accelerators were investigated as a possible method of meeting isotope demand. Linear accelerators are cheaper, safer, and have lower decommissioning costs compared to nuclear reactors. By using (γ,p) reactions, the desired isotope can be separated from the target material due to the different chemical nature of each isotope. Isotopes investigated were Cu-67, In-111, and Lu-111. Using the results the photon flux Monte Carlo simulations, the expected activity of isotopes can be calculated. After samples were irradiated, a high purity germanium detector and signal processing apparatus were used to count the samples. The activity at the time of irradiation stop was then calculated. The uses of medical isotopes will also be presented. Thanks to Idaho State University, the Idaho Accelerator Center, and the National Science Foundation for supporting the research.

Krypton and xenon in lunar fines

NASA Technical Reports Server (NTRS)

Basford, J. R.; Dragon, J. C.; Pepin, R. O.; Coscio, M. R., Jr.; Murthy, V. R.

1973-01-01

Data from grain-size separates, stepwise-heated fractions, and bulk analyses of 20 samples of fines and breccias from five lunar sites are used to define three-isotope and ordinate intercept correlations in an attempt to resolve the lunar heavy rare gas system in a statistically valid approach. Tables of concentrations and isotope compositions are given.

Enzymatic Kinetic Isotope Effects from Path-Integral Free Energy Perturbation Theory.

PubMed

Gao, J

2016-01-01

Path-integral free energy perturbation (PI-FEP) theory is presented to directly determine the ratio of quantum mechanical partition functions of different isotopologs in a single simulation. Furthermore, a double averaging strategy is used to carry out the practical simulation, separating the quantum mechanical path integral exactly into two separate calculations, one corresponding to a classical molecular dynamics simulation of the centroid coordinates, and another involving free-particle path-integral sampling over the classical, centroid positions. An integrated centroid path-integral free energy perturbation and umbrella sampling (PI-FEP/UM, or simply, PI-FEP) method along with bisection sampling was summarized, which provides an accurate and fast convergent method for computing kinetic isotope effects for chemical reactions in solution and in enzymes. The PI-FEP method is illustrated by a number of applications, to highlight the computational precision and accuracy, the rule of geometrical mean in kinetic isotope effects, enhanced nuclear quantum effects in enzyme catalysis, and protein dynamics on temperature dependence of kinetic isotope effects. © 2016 Elsevier Inc. All rights reserved.

Atmosphere-entry behavior of a modular, disk-shaped, isotope heat source.

NASA Technical Reports Server (NTRS)

Vorreiter, J. W.; Pitts, W. C.; Stine, H. A.; Burns, J. J.

1973-01-01

The authors have studied the entry and impact behavior of an isotope heat source for space nuclear power that disassembles into a number of modules which would enter the earth's atmosphere separately if a flight aborted. These modules are disk-shaped units, each with its own reentry heat shield and protective impact container. In normal operation, the disk modules are stacked inside the generator, but during a reentry abort they separate and fly as individual units of low ballistic coefficient. Flight tests at hypersonic speeds have confirmed that a stack of disks will separate and assume a flat-forward mode of flight. Free-fall tests of single disks have demonstrated a nominal impact velocity of 30 m/sec at sea level for a practical range of ballistic coefficients.

Infrared laser system

DOEpatents

Cantrell, Cyrus D.; Carbone, Robert J.; Cooper, Ralph S.

1977-01-01

An infrared laser system and method for isotope separation may comprise a molecular gas laser oscillator to produce a laser beam at a first wavelength, Raman spin flip means for shifting the laser to a second wavelength, a molecular gas laser amplifier to amplify said second wavelength laser beam to high power, and optical means for directing the second wavelength, high power laser beam against a desired isotope for selective excitation thereof in a mixture with other isotopes. The optical means may include a medium which shifts the second wavelength high power laser beam to a third wavelength, high power laser beam at a wavelength coincidental with a corresponding vibrational state of said isotope and which is different from vibrational states of other isotopes in the gas mixture.

Infrared laser system

DOEpatents

Cantrell, Cyrus D.; Carbone, Robert J.; Cooper, Ralph

1982-01-01

An infrared laser system and method for isotope separation may comprise a molecular gas laser oscillator to produce a laser beam at a first wavelength, Raman spin flip means for shifting the laser to a second wavelength, a molecular gas laser amplifier to amplify said second wavelength laser beam to high power, and optical means for directing the second wavelength, high power laser beam against a desired isotope for selective excitation thereof in a mixture with other isotopes. The optical means may include a medium which shifts the second wavelength high power laser beam to a third wavelength, high power laser beam at a wavelength coincidental with a corresponding vibrational state of said isotope and which is different from vibrational states of other isotopes in the gas mixture.

Design of an EBIS charge breeder system for rare-isotope beams

NASA Astrophysics Data System (ADS)

Park, Young-Ho; Son, Hyock-Jun; Kim, Jongwon

2016-09-01

Rare-isotope beams will be produced by using the isotope separation on-line (ISOL) system at the Rare Isotope Science Project (RISP). A proton cyclotron is the driver accelerator for ISOL targets, and uranium carbide (UCx) will be a major target material. An isotope beam of interest extracted from the target will be ionized and selected by using a mass separator. The beam emittance will then be reduced by using a radio-frequency quadrupole (RFQ) cooler before the beam is injected into the electron-beam ion-source (EBIS) charge breeder (CB). The maximum electron beam current of the EBIS is 3 A from a cathode made of IrCe in an applied magnetic field of 0.2 T. The size of the electron beam is compressed by magnetic fields of up to 6 T caused in the charge-breeding region by a superconducting solenoid. The design of EBIS-CB was performed by using mechanics as well as beam optics. A test stand for the electron gun and its collector, which can take an electron-beam power of 20 kW, are under construction. The gun assembly was first tested by using a high-voltage pulse so as to measure its perveance. The design of the EBIS, along with its test stand, is described.

Simultaneous determination of creatinine and creatine in human serum by double-spike isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) and gas chromatography-mass spectrometry (GC-MS).

PubMed

Fernández-Fernández, Mario; Rodríguez-González, Pablo; Añón Álvarez, M Elena; Rodríguez, Felix; Menéndez, Francisco V Álvarez; García Alonso, J Ignacio

2015-04-07

This work describes the first multiple spiking isotope dilution procedure for organic compounds using (13)C labeling. A double-spiking isotope dilution method capable of correcting and quantifying the creatine-creatinine interconversion occurring during the analytical determination of both compounds in human serum is presented. The determination of serum creatinine may be affected by the interconversion between creatine and creatinine during sample preparation or by inefficient chemical separation of those compounds by solid phase extraction (SPE). The methodology is based on the use differently labeled (13)C analogues ((13)C1-creatinine and (13)C2-creatine), the measurement of the isotopic distribution of creatine and creatinine by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and the application of multiple linear regression. Five different lyophilized serum-based controls and two certified human serum reference materials (ERM-DA252a and ERM-DA253a) were analyzed to evaluate the accuracy and precision of the proposed double-spike LC-MS/MS method. The methodology was applied to study the creatine-creatinine interconversion during LC-MS/MS and gas chromatography-mass spectrometry (GC-MS) analyses and the separation efficiency of the SPE step required in the traditional gas chromatography-isotope dilution mass spectrometry (GC-IDMS) reference methods employed for the determination of serum creatinine. The analysis of real serum samples by GC-MS showed that creatine-creatinine separation by SPE can be a nonquantitative step that may induce creatinine overestimations up to 28% in samples containing high amounts of creatine. Also, a detectable conversion of creatine into creatinine was observed during sample preparation for LC-MS/MS. The developed double-spike LC-MS/MS improves the current state of the art for the determination of creatinine in human serum by isotope dilution mass spectrometry (IDMS), because corrections are made for all the possible errors derived from the sample preparation step.

Mercury Stable Isotopic Composition of Monomethylmercury in Estuarine Sediments and Pure Cultures of Mercury Methylating Bacteria

NASA Astrophysics Data System (ADS)

Janssen, S.; Johnson, M. W.; Barkay, T.; Blum, J. D.; Reinfelder, J. R.

2014-12-01

Tracking monomethylmercury (MeHg) from its source in soils and sediments through various environmental compartments and transformations is critical to understanding its accumulation in aquatic and terrestrial food webs. Advances in the field of mercury (Hg) stable isotopes have allowed for the tracking of discrete Hg sources and the examination of photochemical and bacterial transformations. Despite analytical advances, measuring the Hg stable isotopic signature of MeHg in environmental samples or laboratory experiments remains challenging due to difficulties in the quantitative separation of MeHg from complex matrices with high concentrations of inorganic Hg. To address these challenges, we have developed a MeHg isolation method for sediments and bacterial cultures which involves separation by gas chromatography. The MeHg eluting from the GC is passed through a pyrolysis column and purged onto a gold amalgam trap which is then desorbed into a final oxidizing solution. A MeHg reference standard carried through our separation process retained its isotopic composition within 0.02 ‰ for δ202Hg, and for native estuarine sediments, MeHg recoveries were 80% to 100%. For sediment samples from the Hackensack and Passaic Rivers (New Jersey, USA), δ202Hg values for MeHg varied from -1.2 to +0.58 ‰ (relative to SRM 3133) and for individual samples were significantly different from that of total Hg (-0.38 ± 0.06 ‰). No mass independent fractionation was observed in MeHg or total Hg from these sediments. Pure cultures of Geobacter sulfurreducens, grown under fermentative conditions showed preferential enrichment of lighter isotopes (lower δ202Hg) during Hg methylation. The Hg stable isotope signatures of MeHg in sediments and laboratory methylation experiments will be discussed in the context of the formation and degradation of MeHg in the environment and the bioaccumulation of MeHg in estuarine food webs.

Nuclear spectroscopy of r-process nuclei around N = 126 using KISS

NASA Astrophysics Data System (ADS)

Hirayama, Y.; Watanabe, Y. X.; Miyatake, H.; Schury, P.; Wada, M.; Oyaizu, M.; Kakiguchi, Y.; Mukai, M.; Kimura, S.; Ahmed, M.; Jeong, S. C.; Moon, J. Y.; Park, J. H.

2017-09-01

The beta-decay properties and atomic mass of nuclei with neutron magic number of N = 126 are considered critical for understanding the production of heavy elements such as gold and platinum at astrophysical sites. We will produce and measure the half-lives and masses of the nuclei with Z = 74-77 around N = 126 by using the multinucleon transfer (MNT) reaction of ^{136} Xe/ ^{238} U beams and ^{198} Pt target system. For this purpose, we have constructed the KEK Isotope Separation System (KISS) at RIKEN RIBF facility. KISS consists of an argon gas cell based laser ion source (atomic number selection) and an isotope separation on-line (ISOL) (mass number selection), to produce pure low-energy beams of neutron-rich isotopes around N = 126 . We performed the on-line tests to study the basic properties of the KISS and, successfully extracted laser-ionized nuclei around N = 126.

Estimation of the formation rates of polyatomic species of heavy metals in plutonium analyses using a multicollector ICP-MS with a desolvating nebulizer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mitroshkov, Alexandre V.; Olsen, Khris B.; Thomas, Linda M.

2015-01-01

The analyses of IAEA and environmental samples for Plutonium isotopic content are conducted normally at very low concentrations of Pu–usually in the range of part per trillion level and even more often at the parts per quadrillion level. To analyze such low concentrations, the interferences in the analytical solution must be reduced as much as possible. Polyatomic interferences (PIs), formed by the heavy metals (HMs) from Hf to Bi are known to create the problems for Pu isotopic analyses, because even the relatively high resolution of a modern multicollector ICP-MS is not enough to separate Pu isotopes from this PIsmore » in most of the cases. Desolvating nebulizers (DSN) (e.g. APEX and AridusII) reduce significantly the formation of PIs compare to the use of wet plasma. The purpose of this work was to investigate the rate of formation of PIs, produced by HMs, when high resolution MC ICP-MS with desolvating nebulizer was used for Pu isotopic analyses and to estimate the influence of the metals present in the sample on the results of analyses. The NU Plasma HR Multicollector and AridusII desolvating nebulizer were used in this investigation. This investigation was done for all Pu isotopes normally analyzed by ICP-MS, including ²⁴⁴Pu, with the exception of ²³⁸Pu, which most of the time can’t be analyzed by ICP-MS, because of the overwhelming presence of ²³⁸U in the solutions. The PI formation rates were determined and reported for all 12 HMs from Hf to Bi. Selected IAEA samples were scanned for the presence of HMs and the influence of HMs on the results of Pu isotopic analyses was evaluated. It was found that the implemented separation procedure provides sufficient separation of HM from Pu, although the effect of PIs on the measurement of low level isotopes like ²⁴¹Pu and ²⁴²Pu in some cases can still be observed.« less

Nd and Sm isotopic composition of spent nuclear fuels from three material test reactors

DOE PAGES

Sharp, Nicholas; Ticknor, Brian W.; Bronikowski, Michael; ...

2016-11-17

Rare earth elements such as neodymium and samarium are ideal for probing the neutron environment that spent nuclear fuels are exposed to in nuclear reactors. The large number of stable isotopes can provide distinct isotopic signatures for differentiating the source material for nuclear forensic investigations. The rare-earth elements were isolated from the high activity fuel matrix via ion exchange chromatography in a shielded cell. The individual elements were then separated using cation exchange chromatography. In conclusion, the neodymium and samarium aliquots were analyzed via MC–ICP–MS, resulting in isotopic compositions with a precision of 0.01–0.3%.

Nd and Sm isotopic composition of spent nuclear fuels from three material test reactors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sharp, Nicholas; Ticknor, Brian W.; Bronikowski, Michael

Rare earth elements such as neodymium and samarium are ideal for probing the neutron environment that spent nuclear fuels are exposed to in nuclear reactors. The large number of stable isotopes can provide distinct isotopic signatures for differentiating the source material for nuclear forensic investigations. The rare-earth elements were isolated from the high activity fuel matrix via ion exchange chromatography in a shielded cell. The individual elements were then separated using cation exchange chromatography. In conclusion, the neodymium and samarium aliquots were analyzed via MC–ICP–MS, resulting in isotopic compositions with a precision of 0.01–0.3%.

Data Reduction of Laser Ablation Split-Stream (LASS) Analyses Using Newly Developed Features Within Iolite: With Applications to Lu-Hf + U-Pb in Detrital Zircon and Sm-Nd +U-Pb in Igneous Monazite

NASA Astrophysics Data System (ADS)

Fisher, Christopher M.; Paton, Chad; Pearson, D. Graham; Sarkar, Chiranjeeb; Luo, Yan; Tersmette, Daniel B.; Chacko, Thomas

2017-12-01

A robust platform to view and integrate multiple data sets collected simultaneously is required to realize the utility and potential of the Laser Ablation Split-Stream (LASS) method. This capability, until now, has been unavailable and practitioners have had to laboriously process each data set separately, making it challenging to take full advantage of the benefits of LASS. We describe a new program for handling multiple mass spectrometric data sets collected simultaneously, designed specifically for the LASS technique, by which a laser aerosol is been split into two or more separate "streams" to be measured on separate mass spectrometers. New features within Iolite (https://iolite-software.com) enable the capability of loading, synchronizing, viewing, and reducing two or more data sets acquired simultaneously, as multiple DRSs (data reduction schemes) can be run concurrently. While this version of Iolite accommodates any combination of simultaneously collected mass spectrometer data, we demonstrate the utility using case studies where U-Pb and Lu-Hf isotope composition of zircon, and U-Pb and Sm-Nd isotope composition of monazite were analyzed simultaneously, in crystals showing complex isotopic zonation. These studies demonstrate the importance of being able to view and integrate simultaneously acquired data sets, especially for samples with complicated zoning and decoupled isotope systematics, in order to extract accurate and geologically meaningful isotopic and compositional data. This contribution provides instructions and examples for handling simultaneously collected laser ablation data. An instructional video is also provided. The updated Iolite software will help to fully develop the applications of both LASS and multi-instrument mass spectrometric measurement capabilities.

Electrochemically controlled iron isotope fractionation

NASA Astrophysics Data System (ADS)

Black, Jay R.; Young, Edward D.; Kavner, Abby

2010-02-01

Variations in the stable isotope abundances of transition metals have been observed in the geologic record and trying to understand and reconstruct the physical/environmental conditions that produced these signatures is an area of active research. It is clear that changes in oxidation state lead to large fractionations of the stable isotopes of many transition metals such as iron, suggesting that transition metal stable isotope signatures could be used as a paleo-redox proxy. However, the factors contributing to these observed stable isotope variations are poorly understood. Here we investigate how the kinetics of iron redox electrochemistry generates isotope fractionation. Through a combination of electrodeposition experiments and modeling of electrochemical processes including mass-transport, we show that electron transfer reactions are the cause of a large isotope separation, while mass transport-limited supply of reactant to the electrode attenuates the observed isotopic fractionation. Furthermore, the stable isotope composition of electroplated transition metals can be tuned in the laboratory by controlling parameters such as solution chemistry, reaction overpotential, and solution convection. These methods are potentially useful for generating isotopically-marked metal surfaces for tracking and forensic purposes. In addition, our studies will help interpret stable isotope data in terms of identifying underlying electron transfer processes in laboratory and natural samples.

Atomic and Molecular Beam Scattering: Characterizing Structure and Dynamics of Hybrid Organic-Semiconductor Interfaces and Introducing Novel Isotope Separation Techniques

NASA Astrophysics Data System (ADS)

Nihill, Kevin John

This thesis details a range of experiments and techniques that use the scattering of atomic beams from surfaces to both characterize a variety of interfaces and harness mass-specific scattering conditions to separate and enrich isotopic components in a mixture of gases. Helium atom scattering has been used to characterize the surface structure and vibrational dynamics of methyl-terminated Ge(111), thereby elucidating the effects of organic termination on a rigid semiconductor interface. Helium atom scattering was employed as a surface-sensitive, non-destructive probe of the surface. By means of elastic gas-surface diffraction, this technique is capable of providing measurements of atomic spacing, step height, average atomic displacement as a function of surface temperature, gas-surface potential well depth, and surface Debye temperature. Inelastic time-of-flight studies provide highly resolved energy exchange measurements between helium atoms and collective lattice vibrations, or phonons; a collection of these measurements across a range of incident kinematic parameters allowed for a thorough mapping of low-energy phonons (e.g., the Rayleigh wave) across the surface Brillouin zone and subsequent comparison with complementary theoretical calculations. The scattering of molecular beams - here, hydrogen and deuterium from methyl-terminated Si(111) - enables the measurement of the anisotropy of the gas-surface interaction potential through rotationally inelastic diffraction (RID), whereby incident atoms can exchange internal energy between translational and rotational modes and diffract into unique angular channels as a result. The probability of rotational excitations as a function of incident energy and angle were measured and compared with electronic structure and scattering calculations to provide insight into the gas-surface interaction potential and hence the surface charge density distribution, revealing important details regarding the interaction of H2 with an organic-functionalized semiconductor interface. Aside from their use as probes for surface structure and dynamics, atomic beam sources are also demonstrated to enable the efficient separation of gaseous mixtures of isotopes by means of diffraction and differential condensation. In the former method, the kinematic conditions for elastic diffraction result in an incident beam of natural abundance neon diffracting into isotopically distinct angles, resulting in the enrichment of a desired isotope; this purification can be improved by exploiting the difference in arrival times of the two isotopes at a given final angle. In the latter method, the identical incident velocities of coexpanded isotopes lead to minor but important differences in their incident kinetic energies, and thus their probability of adsorbing on a sufficiently cold surface, resulting in preferential condensation of a given isotope that depends on the energy of the incident beam. Both of these isotope separation techniques are made possible by the narrow velocity distribution and velocity seeding effect offered only by high-Mach number supersonic beam sources. These experiments underscore the utility of supersonically expanded atomic and molecular beam sources as both extraordinarily precise probes of surface structure and dynamics and as a means for high-throughput, non-dissociative isotopic enrichment methods.

Particle Spectrometers for FRIB

NASA Astrophysics Data System (ADS)

Amthor, A. M.

2014-09-01

FRIB promises to dramatically expand the variety of nuclear systems available for direct experimental study by providing rates of many rare isotopes orders of magnitude higher than those currently available. A new generation of experimental systems, including new particle spectrometers will be critical to our ability to take full advantage of the scientific opportunities offered by FRIB. The High-Rigidity Spectrometer (HRS) will allow for experiments with the most neutron-rich and short-lived isotopes produced by in-flight fragmentation at FRIB. The bending capability of the HRS (8 Tm) matches to the rigidity for which rare isotopes are produced at the highest intensity in the FRIB fragment separator. The experimental program will be focused on nuclear structure and astrophysics, and allow for the use of other cutting-edge detection systems for gamma, neutron, and charged-particle detection. Stopped and reaccelerated beam studies will be an important compliment to in-flight techniques at FRIB, providing world-unique, high quality, intense rare isotope beams at low energies up to and beyond the Coulomb barrier--with the completion of ReA12--and serving many of the science goals of the broader facility, from nuclear structure and astrophysics to applications. Two specialized recoil spectrometers are being developed for studies with reaccelerated beams. SECAR, the Separator for Capture Reactions, will be built following ReA3, coupled to a windowless gas jet target, JENSA, and will focus on radiative capture reactions for astrophysics, particularly those needed to improve our understanding of novae and X-ray bursts. A recoil separator following ReA12 is proposed to address a variety of physics cases based on fusion-evaporation, Coulomb excitation, transfer, and deep-inelastic reactions by providing a large angular, momentum and charge state acceptance; a high mass resolving power; and the flexibility to couple to a variety of auxiliary detector systems. Two designs have been proposed to meet these needs, ISLA, the Isochronous Separator with Large Acceptance, and an electromagnetic M/Q separator SUPERB, the Separator for the Unique Products of Experiments with Radioactive Beams.

Observation of the 162Dy-164Dy Isotope Shift for the 0 → 16 717.79 cm-1 Optical Transition.

PubMed

Nardin Barreta, Luiz Felipe; Victor, Alessandro Rogério; Bueno, Patrícia; Dos Santos, Jhonatha Ricardo; da Silveira, Carlos Alberto Barbosa; Neri, José Wilson; Neto, Jonas Jakutis; Sbampato, Maria Esther; Destro, Marcelo Geraldo

2017-08-01

In this work, we report a newly observed isotope shift between 162 Dy and 164 Dy isotopes for the 0 → 16 717.79 cm -1 (598.003 nm) optical transition. We compared the newly observed results against two other lines (597.452 nm and 598.859 nm), which we measured in this work, and were already reported in the literature. The newly observed 162-164 Dy isotope shift, shows at least a 20% larger isotope shift than the isotope shifts for the other two lines investigated. The larger 162-164 isotope shift observed for the 598.003 nm line could lead to an increased isotope selectivity for atomic vapor laser isotope separation (AVLIS). Hence, this line could be a good choice for application in AVLIS. Experimental data available in the literature for the 597.452 nm and 598.859 nm lines, enabled us to perform simulations of spectra for both lines, in order to confirm the accuracy of our experimental measurements.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowman, J.R.; Rohrs, D.T.

The isotopic compositions of hydrogen and oxygen have been determined for spring waters and thermal fluids from the Roosevelt Hot Springs and Cove Fort-Sulphurdale thermal areas, for clay mineral separates from shallow alteration of the acid-sulfate type in the Roosevelt Hot Springs area, and for spring and well waters from the Goshen Valley area of central Utah. The water analyses in the Roosevelt Hot Springs thermal area confirm the origin of the thermal fluids from meteoric water in the Mineral Range. The water analyses in the Cove Fort-Sulphurdale thermal area restrict recharge areas for this system to the upper elevationsmore » of the Pavant and/or Tushar Ranges. The low /sup 18/O shift observed in these thermal fluids (+0.7 permil) implies either high water/rock ratios or incomplete isotope exchange or both, and further suggests minimal interaction between the thermal fluid and marble country rock in the system. Hydrogen and oxygen-isotope data for clay mineral separates from shallow alteration zones in the Roosevelt Hot Springs thermal system suggest that the fluids responsible for the shallow acid-sulfate alteration were in part derived from condensed steam produced by boiling of the deep reservoir fluid. The isotope evidence supports the chemical model proposed by Parry et al. (1980) for origin of the acid-sulfate alteration at Roosevelt Hot Springs. The isotope analyses of spring and well waters from the Goshen Valley area indicate only a general correlation of isotope composition, salinity and chemical temperatures.« less

Design of in-flight fragment separator using high-power primary beams in the energy of a few hundred MeV/u

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, J. Y.; Kim, J. W.; Wan, W.

2015-07-15

An in-flight fragment separator usually requires large acceptance and high momentum resolution to minimize the loss of a rare isotope beam of interest produced at a thin target, which is especially important when {sup 238}U fission reactions in the energy of 200 MeV/u are used. The production target and beam dump are located in the pre-separator, where a beam power of up to 400 kW is dissipated. The area is surrounded by thick radiation shielding walls, which result in long drift spaces between adjacent magnetic components at various locations and an asymmetrical layout. Efforts have been made to minimize non-linearmore » effects in the pre-separator beam optics with trials of different separator configurations and correction schemes using COSY Infinity and GICOSY. The main separator is configured to be mirror symmetric such that correction with hexapole and octupole coils can be more readily applied. The separator configuration was finalized to allow the facility design to proceed and the key components including superconducting magnets have been designed and prototyped. In addition, the separator design has been evaluated using LISE++ including a set of wedge degraders at dispersive focal planes to improve the yield and purity of selected isotope beam.« less

Preserving Plutonium-244 as a National Asset

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patton, Bradley D; Alexander, Charles W; Benker, Dennis

Plutonium-244 (244 Pu) is an extremely rare and long-lived isotope of plutonium with a half-life of 80 million years. Measureable amounts of 244 Pu are found in neither reactor-grade nor weapons-grade plutonium. Production of this isotope requires a very high thermal flux to permit the two successive neutron captures that convert 242 Pu to 243 Pu to 244 Pu, particularly given the short (about 5 hour) half-life of 243 Pu. Such conditions simply do not exist in plutonium production processes. Therefore, 244 Pu is ideal for precise radiochemical analyses measuring plutonium material properties and isotopic concentrations in items containing plutonium.more » Isotope dilution mass spectrometry is about ten times more sensitive when using 244 Pu rather than 242 Pu for determining plutonium isotopic content. The isotope can also be irradiated in small quantities to produce superheavy elements. The majority of the existing global inventory of 244 Pu is contained in the outer housing of Mark-18A targets at the Savannah River Site (SRS). The total inventory is about 20 grams of 244 Pu in about 400 grams of plutonium distributed among the 65 targets. Currently, there are no specific plans to preserve these targets. Although the cost of separating and preserving this material would be considerable, it is trivial in comparison to new production costs. For all practical purposes, the material is irreplaceable, because new production would cost billions of dollars and require a series of irradiation and chemical separation cycles spanning up to 50 years. This paper will discuss a set of options for overcoming the significant challenges to preserve the 244 Pu as a National Asset: (1) the need to relocate the material from SRS in a timely manner, (2) the need to reduce the volume of material to the extent possible for storage, and (3) the need to establish an operational capability to enrich the 244 Pu in significant quantities. This paper suggests that if all the Mark-18A plutonium is separated, it would occupy a small volume and would be inexpensive to store while an enrichment capability is developed. Very small quantities could be enriched in existing mass separators to support critical needs.« less

Hydrogen isotope separation

DOEpatents

Bartlit, John R.; Denton, William H.; Sherman, Robert H.

1982-01-01

A system of four cryogenic fractional distillation columns interlinked with two equilibrators for separating a DT and hydrogen feed stream into four product streams, consisting of a stream of high purity D.sub.2, DT, T.sub.2, and a tritium-free stream of HD for waste disposal.

Continuous production of tritium in an isotope-production reactor with a separate circulation system

DOEpatents

Cawley, W.E.; Omberg, R.P.

1982-08-19

A method is described for producing tritium in a fast breeder reactor cooled with liquid metal. Lithium is allowed to flow through the reactor in separate loops in order to facilitate the production and removal of tritium.

A preliminary study for the production of high specific activity radionuclides for nuclear medicine obtained with the isotope separation on line technique.

PubMed

Borgna, F; Ballan, M; Corradetti, S; Vettorato, E; Monetti, A; Rossignoli, M; Manzolaro, M; Scarpa, D; Mazzi, U; Realdon, N; Andrighetto, A

2017-09-01

Radiopharmaceuticals represent a fundamental tool for nuclear medicine procedures, both for diagnostic and therapeutic purposes. The present work aims to explore the Isotope Separation On-Line (ISOL) technique for the production of carrier-free radionuclides for nuclear medicine at SPES, a nuclear physics facility under construction at INFN-LNL. Stable ion beams of strontium, yttrium and iodine were produced using the SPES test bench (Front-End) to simulate the production of 89 Sr, 90 Y, 125 I and 131 I and collected with good efficiency on suitable targets. Copyright © 2017 Elsevier Ltd. All rights reserved.

CONTROL SYSTEM FOR ISOTOPE SEPARATING APPARATUS

DOEpatents

Barnes, S.W.

1960-01-26

A method is described for controlling the position of the ion beams in a calutron used for isotope separation. The U/sup 238/ beams is centered over the U/sup 235/ receiving pocket, the operator monitoring the beam until a maximum reading is achieved on the meter connected to that pocket. Then both beams are simultaneously shifted by a preselected amount to move the U/sup 235/ beam over the U/sup 235/ pocket. A slotted door is placed over the entrance to that pocket during the U/sup 238/ beam centering to reduce the contamination to the pocket, while allowing enough beam to pass for monitoring purposes.

The New Element Berkelium (Atomic Number 97)

DOE R&D Accomplishments Database

Seaborg, G. T.; Thompson, S. G.; Ghiorso, A.

1950-04-26

An isotope of the element with atomic number 97 has been discovered as a product of the helium-ion bombardment of americium. The name berkelium, symbol Bk, is proposed for element 97. The chemical separation of element 97 from the target material and other reaction products was made by combinations of precipitation and ion exchange adsorption methods making use of its anticipated (III) and (IV) oxidation states and its position as a member of the actinide transition series. The distinctive chemical properties made use of in its separation and the equally distinctive decay properties of the particular isotope constitute the principal evidence for the new element.

Multi-Isotopic evidence from West Eifel Xenoliths

NASA Astrophysics Data System (ADS)

Thiemens, M. M.; Sprung, P.

2015-12-01

Mantle Xenoliths from the West Eifel intraplate volcanic field of Germany provide insights into the nature and evolution of the regional continental lithospheric mantle. Previous isotope studies have suggested a primary Paleoproterozoic depletion age, a second partial melting event in the early Cambrian, and a Variscan metasomatic overprint. Textural and Sr-Nd isotopic observations further suggest two episodes of melt infiltration of early Cretaceous and Quaternary age. We have investigated anhydrous, vein-free lherzolites from this region, focusing on the Dreiser Weiher and Meerfelder Maar localities. Hand separated spinel, olivine, ortho- and clinopryoxene, along with host and bulk rocks were dissolved and purified for Rb-Sr, Sm-Nd, and Lu-Hf analysis on the Cologne/Bonn Neptune MC-ICP-MS. We find an unexpected discontinuity between mineral separates and whole rocks. While the latter have significantly more radiogenic ɛNd and ɛHf, mineral separates imply close-to chondritic compositions. Our Lu-Hf data imply resetting of the Lu-Hf systematic after 200 Ma. Given the vein-free nature of the lherzolites, this appears to date to the second youngest metasomatic episode. We suggest that markedly radiogenic Nd and Hf were introduced during the Quarternary metasomatic episode and most likely reside on grain boundaries.

The setup of an extraction system coupled to a hydrogen isotopes distillation column

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zamfirache, M.; Bornea, A.; Stefanescu, I.

2008-07-15

Among the most difficult problems of cryogenic distillation one stands apart: the extraction of the heavy fraction. By an optimal design of the cycle scheme, this problem could be avoided. A 'worst case scenario' is usually occurring when the extracted fraction consists of one prevalent isotope such as hydrogen and small amounts of the other two hydrogen isotopes (deuterium and/or tritium). This situation is further complicated by two parameters of the distillation column: the extraction flow rate and the hold-up. The present work proposes the conceptual design of an extraction system associated to the cryogenic distillation column used in hydrogenmore » separation processes. During this process, the heavy fraction (DT, T{sub 2}) is separated, its concentration being the highest at the bottom of the distillation column. From this place the extraction of the gaseous phase can now begin. Being filled with adsorbent, the extraction system is used to temporarily store the heavy fraction. Also the extraction system provides samples for the gas Chromatograph. The research work is focused on the existent pilot plant for tritium and deuterium separation from our institute to validate the experiments carried out until now. (authors)« less

[Determination of 235U/238U isotope ratios in camphor tree bark samples by MC-ICP-MS after separation of uranium from matrix elements].

PubMed

Wang, Xiao-Ping; Zhang, Ji-Long

2007-07-01

Twelve camphor (cinnamomum camphora) tree bark samples were collected from Hiroshima and Kyoto, and the matrix element composition and morphology of the outer surface of these camphor tree bark samples were studied by EDXS and SEM respectively. After a dry decomposition, DOWEX 1-X8 anion exchange resin was used to separate uranium from matrix elements in these camphor tree bark samples. Finally, 235U/238 U isotope ratios in purified uranium solutions were determined by MC-ICP-MS. It was demonstrated that the outer surface of these camphor tree bark samples is porous and rough, with Al, Ca, Fe, K, Mg, Si, C, O and S as its matrix element composition. Uranium in these camphor tree bark samples can be efficiently separated and quantitatively recovered from the matrix element composition. Compared with those collected from Kyoto, the camphor tree bark samples collected from Hiroshima have significantly higher uranium contents, which may be due to the increased aerosol mass concentration during the city reconstruction. Moreover, the 235 U/23.U isotope ratios in a few camphor tree bark samples collected from Hiroshima are slightly higher than 0.007 25.

Parasitic production of slow RI-beam from a projectile fragment separator by ion guide Laser Ion Source (PALIS)

NASA Astrophysics Data System (ADS)

Sonoda, Tetsu

2009-10-01

The projectile fragment separator BigRIPS of RIBF at RIKEN provides a wide variety of short-lived radioactive isotope (RI) ions without restrictions on their lifetime or chemical properties. A universal slow RI-beam facility (SLOWRI) to decelerate the beams from BigRIPS using an RF-carpet ion guide has been proposed as a principal facility of RIBF. However, beam time at such a modern accelerator facility is always limited and operational costs are high. We therefore propose an additional scheme as a complementary option to SLOWRI to drastically enhance the usability of such an expensive facility. In BigRIPS, a single primary beam produces thousands of isotopes but only one isotope is used for an experiment while the other >99.99% of isotopes are simply dumped in the slits or elsewhere in the fragment separator. We plan to locate a compact gas cell with 1 bar Ar at the slits. The thermalized ions in the cell will be quickly neutralized and transported to the exit by gas flow and resonantly re-ionized by lasers. Such low energy RI-beams will always be provided without any restriction to the main experiment. It will allow us to run parasitic experiments for precision atomic or decay spectroscopy, mass measurements. Furthermore, the resonance ionization in the cell itself can be used for high-sensitive laser spectroscopy, which will expand our knowledge of the ground state property of unstable nuclei.

Femtosecond Laser Ablation Multicollector ICPMS Analysis of Uranium Isotopes in NIST Glass

DOE Office of Scientific and Technical Information (OSTI.GOV)

Duffin, Andrew M.; Springer, Kellen WE; Ward, Jesse D.

We have utilized femtosecond laser ablation coupled to multi-collector inductively couple plasma mass spectrometry to measure the uranium isotopic content of NIST 61x (x=0,2,4,6) glasses. The uranium content of these glasses is a linear two-component mixing between isotopically natural uranium and the isotopically depleted spike used in preparing the glasses. Laser ablation results match extremely well, generally within a few ppm, with solution analysis following sample dissolution and chemical separation. In addition to isotopic data, sample utilization efficiency measurements indicate that over 1% of ablated uranium atoms reach a mass spectrometer detector, making this technique extremely efficient. Laser sampling alsomore » allows for spatial analysis and our data indicate that rare uranium concentration inhomogeneities exist in NIST 616 glass.« less

Iron speciation and isotope fractionation during silicate weathering and soil formation in an alpine glacier forefield chronosequence

NASA Astrophysics Data System (ADS)

Kiczka, Mirjam; Wiederhold, Jan G.; Frommer, Jakob; Voegelin, Andreas; Kraemer, Stephan M.; Bourdon, Bernard; Kretzschmar, Ruben

2011-10-01

The chemical weathering of primary Fe-bearing minerals, such as biotite and chlorite, is a key step of soil formation and an important nutrient source for the establishment of plant and microbial life. The understanding of the relevant processes and the associated Fe isotope fractionation is therefore of major importance for the further development of stable Fe isotopes as a tracer of the biogeochemical Fe cycle in terrestrial environments. We investigated the Fe mineral transformations and associated Fe isotope fractionation in a soil chronosequence of the Swiss Alps covering 150 years of soil formation on granite. For this purpose, we combined for the first time stable Fe isotope analyses with synchrotron-based Fe-EXAFS spectroscopy, which allowed us to interpret changes in Fe isotopic composition of bulk soils, size fractions, and chemically separated Fe pools over time in terms of weathering processes. Bulk soils and rocks exhibited constant isotopic compositions along the chronosequence, whereas soil Fe pools in grain size fractions spanned a range of 0.4‰ in δ 56Fe. The clay fractions (<2 μm), in which newly formed Fe(III)-(hydr)oxides contributed up to 50% of the total Fe, were significantly enriched in light Fe isotopes, whereas the isotopic composition of silt and sand fractions, containing most of the soil Fe, remained in the range described by biotite/chlorite samples and bulk soils. Iron pools separated by a sequential extraction procedure covered a range of 0.8‰ in δ 56Fe. For all soils the lightest isotopic composition was observed in a 1 M NH 2OH-HCl-25% acetic acid extract, targeting poorly-crystalline Fe(III)-(hydr)oxides, compared with easily leachable Fe in primary phyllosilicates (0.5 M HCl extract) and Fe in residual silicates. The combination of the Fe isotope measurements with the speciation data obtained by Fe-EXAFS spectroscopy permitted to quantitatively relate the different isotope pools forming in the soils to the mineral weathering reactions which have taken place at the field site. A kinetic isotope effect during the Fe detachment from the phyllosilicates was identified as the dominant fractionation mechanism in young weathering environments, controlling not only the light isotope signature of secondary Fe(III)-(hydr)oxides but also significantly contributing to the isotope signature of plants. The present study further revealed that this kinetic fractionation effect can persist over considerable reaction advance during chemical weathering in field systems and is not only an initial transient phenomenon.

Report on Initial Direct Soil Leaching Experiments Using Post-Detonation Debris

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gostic, R.; Knight, K. B.; Borg, L.

2011-08-01

A key challenge of nuclear forensics is reducing the time and manpower effort required to measure nuclear debris compositions. The overall motivation for this work is to explore development of a robust, automated system that can be used to concurrently analyze several elements/isotopes associated with the forensic signature of nuclear materials. The primary focus of this research has been to methodically investigate if rapid partial leaching of post-detonation debris can yield usable elemental and isotopic information for interpretation. The unique requirements of post-detonation nuclear forensics have not been fully adapted to or fully incorporated contemporary chemical separation techniques. Challenges includemore » addressing the range of material matrices or mixed fission product and actinide compositions and concentrations that might be encountered. These include, but are not limited to, puddle melt glass, urban debris, seawater, air filters, iron-rich urban debris, asphalt, and silica sand. Separation of these elements and their subsequent measurement is a key element of related laboratory analysis activity. Existing practices at LLNL rely on proven but time-consuming and labor intensive processes. Significant time and labor savings are possible in chemical separations, however, if rapid processing methods can be adapted to post-detonation debris. Development of a simple and reliable leaching technique could shorten analytical times and would be useful as a field deployable method for the preliminary characterization of actinide isotopic ratios in soils. Measurement of isotopic ratios in the field using modern mass spectrometry capabilities such as Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is desirable, taking advantage of the extended range of isotopic systems measureable using such instruments. Sample introduction to these types of mass spectrometry instruments requires partial leaching or full dissolution of a sample to remove isobaric (same mass) interferences, and, in some cases, to concentrate the elements(s) of interest. To develop a field-deployable mass spectrometry capability, therefore, automated and robust leaching of likely debris samples (ranging from silicates and oxides to metals and urban materials such as concrete and asphalt), followed by separation/purification through cation exchange column chemistry is necessary. In a post-detonation environment, analysis of melt glasses via rapid leaching and ICP-MS could be a viable route to the same goal. This report presents initial leaching experiments on ‘uncontaminated’ soils, as well as data from melt glass from a single nuclear weapons test. Samples were characterized by gamma spectrometry, then aliquoted for rapid leaching experiments. Experiments were conducted using two different rapid acid treatments to leach the soils. Following leaching, the leachate solutions were analyzed by ICP-MS to determine if U isotopic composition. We present these data to address the question as to whether or not rapid (~1 hr) leaching techniques have the potential to yield meaningful U isotopic compositions, without the need for a complete (time consuming) sample dissolution and separation.« less

Isotopic generator for bismuth-212 and lead-212 based on radium

DOEpatents

Hines, J.J.; Atcher, R.W.; Friedman, A.M.

1985-01-30

Disclosed are method and apparatus for providing radionuclides of bismuth-212 and lead-212. Thorium-228 and carrier solution starting material is input to a radiologically contained portion of an isotopic generator system, and radium-224 is separated from thorium-228 which is retained by a strongly basic anion exchange column. The separated radium-224 is transferred to an accessible, strongly acidic cationic exchange column. The cationic column retains the radium-224, and natural radioactive decay generates bismuth-212 and lead-212. The cationic exchange column can also be separated from the contained portion of the system and utilized without the extraordinary safety measures necessary in the contained portion. Furthermore, the cationic exchange column provides over a relatively long time period the short lived lead-212 and bismuth-212 radionuclides which are useful for a variety of medical therapies.

Isotopic generator for bismuth-212 and lead-212 from radium

DOEpatents

Atcher, Robert W.; Friedman, Arnold M.; Hines, John

1987-01-01

A method and apparatus for providing radionuclides of bismuth-212 and lead-212. Thorium-228 and carrier solution starting material is input to a radiologically contained portion of an isotopic generator system, and radium-224 is separated from thorium-228 which is retained by a strongly basic anion exchange column. The separated radium-224 is transferred to an accessible, strongly acidic cationic exchange column. The cationic column retains the radium-224, and natural radioactive decay generates bismuth-212 and lead-212. The cationic exchange column can also be separated from the contained portion of the system and utilized without the extraordinary safety measures necessary in the contained portion. Furthermore, the cationic exchange column provides over a relatively long time period the short lived lead-212 and bismuth-212 radionuclides which are useful for a variety of medical therapies.

Methods for the separation of rhenium, osmium and molybdenum applicable to isotope geochemistry

USGS Publications Warehouse

Morgan, J.W.; Golightly, D.W.; Dorrzapf, A.F.

1991-01-01

Effective methods are described for the chemical separation of rhenium, osmium and molybdenum. The methods are based on distillation and anion-exchange chromatography, and have been the basis for rhenium-osmium isotope studies of ore deposits and meteorites. Successful anion-exchange separation of osmium requires both recognition and careful control of the osmium species in solution; thus, distillation of osmium tetroxide from a mixture of sulfuric acid and hydrogen peroxide is preferred to anion-exchange. Distribution coefficients measured for perrhenate in sulfuric acid media are sufficiently high (Kd > 500) for rhenium to be directly loaded onto an ion-exchange column from a distillation residue and subsequently eluted with nitric acid. Polymerization of molybdenum species during elution is prevented by use of a solution that is 1M in hydrochloric acid and 1M in sodium chloride. ?? 1991.

Hydrogen isotope separation from water

DOEpatents

Jensen, R.J.

1975-09-01

A process for separating tritium from tritium-containing water or deuterium enrichment from water is described. The process involves selective, laser-induced two-photon excitation and photodissociation of those water molecules containing deuterium or tritium followed by immediate reaction of the photodissociation products with a scavenger gas which does not substantially absorb the laser light. The reaction products are then separated from the undissociated water. (auth)

Detecting intraannual dietary variability in wild mountain gorillas by stable isotope analysis of feces

PubMed Central

Blumenthal, Scott A.; Chritz, Kendra L.; Rothman, Jessica M.; Cerling, Thure E.

2012-01-01

We use stable isotope ratios in feces of wild mountain gorillas (Gorilla beringei) to test the hypothesis that diet shifts within a single year, as measured by dry mass intake, can be recovered. Isotopic separation of staple foods indicates that intraannual changes in the isotopic composition of feces reflect shifts in diet. Fruits are isotopically distinct compared with other staple foods, and peaks in fecal δ13C values are interpreted as periods of increased fruit feeding. Bayesian mixing model results demonstrate that, although the timing of these diet shifts match observational data, the modeled increase in proportional fruit feeding does not capture the full shift. Variation in the isotopic and nutritional composition of gorilla foods is largely independent, highlighting the difficulty for estimating nutritional intake with stable isotopes. Our results demonstrate the potential value of fecal sampling for quantifying short-term, intraindividual dietary variability in primates and other animals with high temporal resolution even when the diet is composed of C3 plants. PMID:23236160

Protein Stable Isotope Fingerprinting (P-SIF): A New Tool to Understand Natural Isotopic Heterogeneity of Mixed Microbial Ecosystems

NASA Astrophysics Data System (ADS)

Pearson, A.; Mohr, W.; Tang, T.; Sattin, S.; Bovee, R.

2014-12-01

Protein stable isotope fingerprinting (P-SIF) is a method to measure the carbon isotope ratios of whole proteins separated from complex mixtures, including cultures and environmental samples. The goal of P-SIF is to expose the links between identity and function in microbial ecosystems by (i) determining the ratios of 13C/12C (values of δ13C) for different taxonomic divisions, and (ii) using those values as clues to the metabolic pathways employed by the respective organisms, while (iii) not perturbing the system, i.e., not adding exogenous substrates or isotope labels. To accomplish this, we employ two-dimensional HPLC to resolve a sample containing ca. 5-10 mg of mixed proteins into 960-1440 fractions. Each fraction then is split in two aliquots: The first is digested with trypsin for peptide sequencing, while the second is measured in triplicate using an isotope-ratio mass spectrometer interfaced with a spooling wire microcombustion device. Data from pure cultures show that bacteria have a narrow distribution of protein δ13C values within individual taxa (±0.7-1.2‰, 1σ). This is moderately larger than the mean precision of the triplicate isotope measurements (±0.5‰, 1σ) and may reflect heterogeneous distribution of 13C among the amino acids. When cells from different species are mixed together prior to protein extraction and separation, the results can predict accurately (to within ±1σ) the δ13C values of the original taxa. The number of data points required for this endmember prediction is ≥20/taxon, yielding a theoretical resolution of ca. 10 taxonomic units/sample. Initial tests on environmental samples suggest the approach will be useful to determine the overall trophic breadth of mixed microbial ecosystems.

Hydrogen isotope separation

DOEpatents

Bartlit, J.R.; Denton, W.H.; Sherman, R.H.

Disclosed is a system of four cryogenic fractional distillation columns interlinked with two equilibrators for separating a DT and hydrogen feed stream into four product streams, consisting of a stream of high purity D/sub 2/, DT, T/sub 2/, and a tritium-free stream of HD for waste disposal.

Determination of 241Am in sediments by isotope dilution high resolution inductively coupled plasma mass spectrometry (ID HR ICP-MS).

PubMed

Agarande, M; Benzoubir, S; Bouisset, P; Calmet, D

2001-08-01

Trace levels (pg kg(-1)) of 241Am in sediments were determined by isotope dilution high resolution inductively coupled plasma mass spectrometry (ID HR ICP-MS) using a microconcentric nebulizer. 241Am was isolated from major elements like Ca and Fe by different selective precipitations. In further steps. Am was first separated from other transuranic elements and purified by anion exchange and extraction chromatography prior to the mass spectrometric measurements. The ID HR ICP-MS results are compared with isotope dilution alpha spectrometry.

High-Throughput Method for Strontium Isotope Analysis by Multi-Collector-Inductively Coupled Plasma-Mass Spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wall, Andrew J.; Capo, Rosemary C.; Stewart, Brian W.

2016-09-22

This technical report presents the details of the Sr column configuration and the high-throughput Sr separation protocol. Data showing the performance of the method as well as the best practices for optimizing Sr isotope analysis by MC-ICP-MS is presented. Lastly, this report offers tools for data handling and data reduction of Sr isotope results from the Thermo Scientific Neptune software to assist in data quality assurance, which help avoid issues of data glut associated with high sample throughput rapid analysis.

High-Throughput Method for Strontium Isotope Analysis by Multi-Collector-Inductively Coupled Plasma-Mass Spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hakala, Jacqueline Alexandra

2016-11-22

This technical report presents the details of the Sr column configuration and the high-throughput Sr separation protocol. Data showing the performance of the method as well as the best practices for optimizing Sr isotope analysis by MC-ICP-MS is presented. Lastly, this report offers tools for data handling and data reduction of Sr isotope results from the Thermo Scientific Neptune software to assist in data quality assurance, which help avoid issues of data glut associated with high sample throughput rapid analysis.

Mantle Helium and Carbon Isotopes in Separation Creek Geothermal Springs, Three Sisters Area, Central Oregon: Evidence for Renewed Volcanic Activity or a Long Term Steady State System?

USGS Publications Warehouse

Van Soest, M. C.; Kennedy, B.M.; Evans, William C.; Mariner, R.H.

2002-01-01

Here we present the helium and carbon isotope results from the initial study of a fluid chemistry-monitoring program started in the summer of 2001 near the South Sister volcano in central Oregon. The Separation Creek area which is several miles due west of the volcano is the locus of strong crustal uplift currently occurring at a rate of 4-5 cm/yr (Wicks, et. al., 2001).Helium [RC/RA = 7.44 and 8.61 RA (RC/R A = (3He/4He)sample-. air corrected/(3He/4He)air))] and carbon (??13C = -11.59 to -9.03??? vs PDB) isotope data and CO2/3He (5 and 9 ?? 109) show that bubbling cold springs in the Separation Creek area near South Sister volcano carry a strong mantle signal, indicating the presence of fresh basaltic magma in the volcanic plumbing system. There is no evidence though, to directly relate this signal to the crustal uplift that is currently taking place in the area, which started in 1998. The geothermal system in the area is apparently much longer lived and shows no significant changes in chemistry compared to data from the early 1990s. Hot springs in the area, which are relatively far removed from the volcanic edifice, do not carry a strong mantle signal in helium isotope ratios (2.79 to 5.08 RA), unlike the cold springs, and also do not show any significant changes in helium isotope ratios compared to literature data for the same springs of over two decades ago. The cold springs of the Separation Creek area form a very diffuse but significant low temperature geothermal system, that should, due to its close vicinity to the center of up uplift, be more sensitive to changes in the deeper volcanic plumbing system than the far removed hot springs and therefore require much more study and consideration when dealing with volcano monitoring in the Cascade range or possibly with geothermal exploration in general.

Copper and tin isotopic analysis of ancient bronzes for archaeological investigation: development and validation of a suitable analytical methodology.

PubMed

Balliana, Eleonora; Aramendía, Maite; Resano, Martin; Barbante, Carlo; Vanhaecke, Frank

2013-03-01

Although in many cases Pb isotopic analysis can be relied on for provenance determination of ancient bronzes, sometimes the use of "non-traditional" isotopic systems, such as those of Cu and Sn, is required. The work reported on in this paper aimed at revising the methodology for Cu and Sn isotope ratio measurements in archaeological bronzes via optimization of the analytical procedures in terms of sample pre-treatment, measurement protocol, precision, and analytical uncertainty. For Cu isotopic analysis, both Zn and Ni were investigated for their merit as internal standard (IS) relied on for mass bias correction. The use of Ni as IS seems to be the most robust approach as Ni is less prone to contamination, has a lower abundance in bronzes and an ionization potential similar to that of Cu, and provides slightly better reproducibility values when applied to NIST SRM 976 Cu isotopic reference material. The possibility of carrying out direct isotopic analysis without prior Cu isolation (with AG-MP-1 anion exchange resin) was investigated by analysis of CRM IARM 91D bronze reference material, synthetic solutions, and archaeological bronzes. Both procedures (Cu isolation/no Cu isolation) provide similar δ (65)Cu results with similar uncertainty budgets in all cases (±0.02-0.04 per mil in delta units, k = 2, n = 4). Direct isotopic analysis of Cu therefore seems feasible, without evidence of spectral interference or matrix-induced effect on the extent of mass bias. For Sn, a separation protocol relying on TRU-Spec anion exchange resin was optimized, providing a recovery close to 100 % without on-column fractionation. Cu was recovered quantitatively together with the bronze matrix with this isolation protocol. Isotopic analysis of this Cu fraction provides δ (65)Cu results similar to those obtained upon isolation using AG-MP-1 resin. This means that Cu and Sn isotopic analysis of bronze alloys can therefore be carried out after a single chromatographic separation using TRU-Spec resin. Tin isotopic analysis was performed relying on Sb as an internal standard used for mass bias correction. The reproducibility over a period of 1 month (n = 42) for the mass bias-corrected Sn isotope ratios is in the range of 0.06-0.16 per mil (2 s), for all the ratios monitored.

A target for production of radioxenons

NASA Technical Reports Server (NTRS)

Blue, J. W.; Leonard, R.; Jha, S.; Sodd, V. J.; Vincent, J. S.

1976-01-01

A liquid cesium target has been developed which allows the production and separate identification of the neutron deficient isotopes of xenon. The present report describes irradiations utilizing 34 to 41 MeV protons to produce millicurie quantities of Xe-127 and Xe-129m. At higher energies, however, the target could be used without modification to produce xenon isotopes as light as 119.

Process chemistry of americium-241

DOE Office of Scientific and Technical Information (OSTI.GOV)

Navratil, J.D.

1983-01-01

Americium-241, one of the most useful actinide isotopes, is produced as a by-product of plutonium scrap recovery operations. Rocky Flats has supplied high purity americium oxide to the US Department of Energy's Isotope Pool since 1962. Over the years, the evolving separation and purification processes have included such diverse operations as ion exchange, aqueous precipitation, and both molten-salt and organic-solvent extraction.

Identifying the groundwater basin boundaries, using environmental isotopes: a case study

NASA Astrophysics Data System (ADS)

Demiroğlu, Muhterem

2017-06-01

Groundwater, which is renewable under current climatic conditions separately from other natural sources, in fact is a finite resource in terms of quality and fossil groundwater. Researchers have long emphasized the necessity of exploiting, operating, conserving and managing groundwater in an efficient and sustainable manner with an integrated water management approach. The management of groundwater needs reliable information about changes on groundwater quantity and quality. Environmental isotopes are the most important tools to provide this support. No matter which method we use to calculate the groundwater budget and flow equations, we need to determine boundary conditions or the physical boundaries of the domain. The Groundwater divide line or basin boundaries that separate the two adjacent basin recharge areas from each other must be drawn correctly to be successful in defining complex groundwater basin boundary conditions. Environmental isotope data, as well as other methods provide support for determining recharge areas of the aquifers, especially for karst aquifers, residence time and interconnections between aquifer systems. This study demonstrates the use of environmental isotope data to interpret and correct groundwater basin boundaries giving as an example the Yeniçıkrı basin within the main Sakarya basin.

An Update on the Non-Mass-Dependent Isotope Fractionation under Thermal Gradient

NASA Technical Reports Server (NTRS)

Sun, Tao; Niles, Paul; Bao, Huiming; Socki, Richard; Liu, Yun

2013-01-01

Mass flow and compositional gradient (elemental and isotope separation) occurs when flu-id(s) or gas(es) in an enclosure is subjected to a thermal gradient, and the phenomenon is named thermal diffusion. Gas phase thermal diffusion has been theoretically and experimentally studied for more than a century, although there has not been a satisfactory theory to date. Nevertheless, for isotopic system, the Chapman-Enskog theory predicts that the mass difference is the only term in the thermal diffusion separation factors that differs one isotope pair to another,with the assumptions that the molecules are spherical and systematic (monoatomic-like structure) and the particle collision is elastic. Our previous report indicates factors may be playing a role because the Non-Mass Dependent (NMD) effect is found for both symmetric and asymmetric, linear and spherical polyatomic molecules over a wide range of temperature (-196C to +237C). The observed NMD phenomenon in the simple thermal-diffusion experiments demands quantitative validation and theoretical explanation. Besides the pressure and temperature dependency illustrated in our previous reports, efforts are made in this study to address issues such as the role of convection or molecular structure and whether it is a transient, non-equilibrium effect only.

Simulation and Analysis of Isotope Separation System for Fusion Fuel Recovery System

NASA Astrophysics Data System (ADS)

Senevirathna, Bathiya; Gentile, Charles

2011-10-01

This paper presents results of a simulation of the Fuel Recovery System (FRS) for the Laser Inertial Fusion Engine (LIFE) reactor. The LIFE reaction will produce exhaust gases that will need to be recycled in the FRS along with xenon, the chamber's intervention gas. Solids and liquids will first be removed and then vapor traps are used to remove large gas molecules such as lead. The gas will be reacted with lithium at high temperatures to extract the hydrogen isotopes, protium, deuterium, and tritium in hydride form. The hydrogen isotopes will be recovered using a lithium blanket processing system already in place and this product will be sent to the Isotope Separation System (ISS). The ISS will be modeled in software to analyze its effectiveness. Aspen HYSYS was chosen for this purpose for its widespread use industrial gas processing systems. Reactants and corresponding chemical reactions had to be initialized in the software. The ISS primarily consists of four cryogenic distillation columns and these were modeled in HYSYS based on design requirements. Fractional compositions of the distillate and liquid products were analyzed and used to optimize the overall system.

β-decay spectroscopy of r-process nuclei with N = 126 at KISS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirayama, Y.; Watanabe, Y. X.; Imai, N.

2014-05-02

The β-decay properties of nuclei with N = 126, which are believed to act as progenitors in the rapid neutron capture (r-) process path forming the third peak (A ∼ 195) in the observed r-abundance element distribution, are considered critical for understanding the production of heavy elements such as gold and platinum at astrophysical sites. We have constructed the KEK Isotope Separation System (KISS), which consists of a gas cell based laser ion source (atomic number selection) and an isotope separation on-line (ISOL) (mass number selection), to produce pure low-energy beams of neutron-rich isotopes around N = 126 and tomore » study their β-decay properties, which are also of interest for astrophysics. The isotopes of interest will be produced by multi-nucleon transfer reactions in heavy ion collisions (e.g. {sup 136}Xe projectile on {sup 198}Pt target). KISS will allow us to study unknown isotopes produced in weak reaction channels under low background conditions. We successfully extracted the stable {sup 56}Fe beam from KISS at the last commissioning on-line experiment with the extraction efficiency of 0.25% and beam purity of more than 98%. We can access the nuclei with N = 126 and measure their half-lives using the KISS in the case of the extraction efficiency of 0.1%.« less

Integrated carbon and chlorine isotope modeling: applications to chlorinated aliphatic hydrocarbons dechlorination.

PubMed

Jin, Biao; Haderlein, Stefan B; Rolle, Massimo

2013-02-05

We propose a self-consistent method to predict the evolution of carbon and chlorine isotope ratios during degradation of chlorinated hydrocarbons. The method treats explicitly the cleavage of isotopically different C-Cl bonds and thus considers, simultaneously, combined carbon-chlorine isotopologues. To illustrate the proposed modeling approach we focus on the reductive dehalogenation of chlorinated ethenes. We compare our method with the currently available approach, in which carbon and chlorine isotopologues are treated separately. The new approach provides an accurate description of dual-isotope effects regardless of the extent of the isotope fractionation and physical characteristics of the experimental system. We successfully applied the new approach to published experimental results on dehalogenation of chlorinated ethenes both in well-mixed systems and in situations where mass-transfer limitations control the overall rate of biodegradation. The advantages of our self-consistent dual isotope modeling approach proved to be most evident when isotope fractionation factors of carbon and chlorine differed significantly and for systems with mass-transfer limitations, where both physical and (bio)chemical transformation processes affect the observed isotopic values.

METHOD OF SEPARATING HYDROGEN ISOTOPES

DOEpatents

Salmon, O.N.

1958-12-01

The process of separating a gaseous mixture of hydrogen and tritium by contacting finely dlvided palladium with the mixture in order to adsorb the gases, then gradually heating the palladium and collecting the evolved fractlons, is described. The fraction first given off is richer in trltium than later fractions.

Stable Nickel Isotopes in Fusion Crusts from Iron Meteorites and from Metallic Particles in a Black Wabar Impact Glass

NASA Astrophysics Data System (ADS)

Xue, S.; Herzog, G. F.; Hall, G. S.

1993-07-01

Iron and nickel isotopes may undergo mass fractionation in systems subjected to high-temperature vaporization [1-3]. We report here a search for nickel fractionation in fusion crusts from iron meteorites and in metal-rich material separated from Wabar impact glasses. Fusion-crust bearing samples of Bogou (IA), N'Goureyma (I-an), and Pitts (IB) were potted in epoxy and were "shaved" with a milling machine. Microscopic examination of the shavings showed the presence of some material from the interior of the meteorites as well as from the fusion crust. A fourth meteorite, Cape of Good Hope (IVB), was prepared for use as a reference standard. About 1.4 mg of magnetic material was collected from a 2-g sample of black Wabar impact glass ground in a Spex mill; microscopic examination indicated that adhering silicates comprised ~5% of the sample. These (terrestrial) silicates contain relatively little Ni [4] so their presence does not interfere with the nickel analysis. Nickel was separated from all samples and its isotopic composition determined as in [2]. Results and Discussion: Nickel isotopic abundances are given in Table 1 both as delta values and as an average fractionation, PHI, where PHI is the slope of a plot of delta vs. mass for each sample. Within the precision of our measurements (from 0.3 to 1.5%, depending on the isotope) all the samples had normal (i.e., terrestrial) isotopic abundances of Ni. Clayton et al. [5] reported that delta-18O in fusion crust is lower than in the atmosphere, probably as a result of a kinetic isotope effect, while in metallic deep-sea spheres, heavy oxygen isotopes are enriched. They inferred that the metallic spheres are not the ablation products of larger meteorites. Similarly, the Ni isotopic abundances in fusion crust are normal, while those in deep-sea metallic spheres are enriched in the heavier isotopes [1]. We note, however, that material ablated from the surface of an iron could have undergone fractionation after separation from the incoming meteorite (see [4]). Horz et al. [6] found variable Fe/Ni ratios (from 0.1 to 222) in black melt glasses associated with the Wabar impact. The Fe/Ni ratio in our metal sample is 2, which is considerably lower than that in the bulk meteorite (~12.4). Several lines of evidence suggest that vapor fractionation is to be expected in samples that have Fe/Ni ratios greater than those in the bulk impactor [2-6]. Thus it is not surprising that our first results for Wabar impactites show no Ni isotopic fractionation. Isotopic analyses of Wabar impactites with high Fe/Ni ratios should be made to test the importance of vapor fractionation. References: [1] Herzog G. F. et al. (1992) LPSC XXIII, 527-528. [2] Xue S. et al. (1993) LPSC XXIV, 1547-1548. [3] Davis A. et al. (1993) LPSC XXIV, 373- 374. [4] Mittlefehldt D. W. et al. (1992) Meteoritics, 27, 361-370. [5] Clayton R. N. et al. (1986) EPSL, 79, 235-240. [6] Horz F. et al. (1989) Proc. LPSC 19th, 697-710. Table 1, which appears in the hard copy, shows delta (permil) and average isotope fractionation PHI (%/amu) for Ni isotopes in iron meteorites and black Wabar impact glass.

Returning from the deep: Archean atmospheric fingerprints in modern hotspot lavas (Invited)

NASA Astrophysics Data System (ADS)

Jackson, M. G.; Cabral, R. A.; Rose-Koga, E. F.; Koga, K. T.; Whitehouse, M. J.; Antonelli, M. A.; Farquhar, J.; Day, J. M.; Hauri, E. H.

2013-12-01

Ocean plates transport surface materials, including oceanic crust and sediment, into the mantle at subduction zones. However, the fate of the subducted package--oceanic crust and sediment--in the mantle is poorly understood. A long-standing hypothesis maintains that subducted materials reside in the mantle for an extended, but unknown, period of time and are then recycled back to the Earth's surface in regions of buoyantly upwelling mantle and melted beneath hotspots. Sulfur isotopes provide an important new tool to evaluate the presence of ancient recycled materials in hotspot lavas. Widespread terrestrial mass independently fractionated sulfur (MIF-S) isotope signatures were generated exclusively through atmospheric photochemical reactions until ~2.45 Ga. In fact, the only significant reservoirs of MIF-S containing rocks documented so far are sediments and hydrothermal rocks older than ~2.45 Ga. Armed with this insight, we examined sulfur isotopes in olivine phenocrysts and olivine-hosted sulfides in lavas from the island of Mangaia, Cook Islands. Lavas from this location host unusually radiogenic Pb-isotopic compositions--referred to as a HIMU (high U/Pb) component--and this has been attributed to ancient recycled oceanic crust in the mantle source. In Cabral et al. (2013), we report MIF-S in olivine phenocrysts and olivine-hosted sulfides. The discovery of MIF-S isotopic signatures in young hotspot lavas appears to provide a "timestamp" and "signature" for preservation of subducted Archean surface materials in the mantle sourcing Mangaia lavas. We report new sulfur isotope data on olivine-hosted sulfides from the Mangaia lavas that reinforce our discovery of MIF-S anomalies reported in Cabral et al. (2013). We also report new sulfur isotopic data on Mangaia whole rock powders, and we find no evidence of MIF-S signatures. It is not yet clear why the individual Mangaia sulfides and the olivine separates have more extreme MIF-S than the whole rocks. We consider it likely that the MIF-S anomaly measured in the olivine separates was diminished relative to the olivine-hosted sulfides by incorporation of modern sulfur into the olivine separates by low-temperature processes operating on the rocks during the 20 Ma since eruption: The absence of a MIF-S anomaly in the whole rock that has olivine-hosted sulfides with MIF-S anomalies may be a result of near-complete replacement of the magmatic sulfur (with a MIF-S anomaly) with modern sulfur (with no MIF-S anomaly) during surficial weathering over 20 Ma. The sulfur in the olivine-hosted sulfides with the largest MIF-S anomalies represents a very small proportion of the sulfur in a bulk basaltic rock and therefore do not impart a clear MIF-S anomaly on the bulk rock analysis. Very few data are available to evaluate this hypothesis. Therefore, pairing sulfur isotope measurements with whole rocks, mineral separates and olivine-hosted sulfides with careful petrographic and electron probe analyses of the samples will be critical for evaluating the origin of the sulfides--primary magmatic or secondary--and the origin and distribution of the sulfur-isotopic signatures in OIB.

Existing and emerging technologies for measuring stable isotope labelled retinol in biological samples: isotope dilution analysis of body retinol stores.

PubMed

Preston, Tom

2014-01-01

This paper discusses some of the recent improvements in instrumentation used for stable isotope tracer measurements in the context of measuring retinol stores, in vivo. Tracer costs, together with concerns that larger tracer doses may perturb the parameter under study, demand that ever more sensitive mass spectrometric techniques are developed. GCMS is the most widely used technique. It has high sensitivity in terms of sample amount and uses high resolution GC, yet its ability to detect low isotope ratios is limited by background noise. LCMSMS may become more accessible for tracer studies. Its ability to measure low level stable isotope tracers may prove superior to GCMS, but it is isotope ratio MS (IRMS) that has been designed specifically for low level stable isotope analysis through accurate analysis of tracer:tracee ratios (the tracee being the unlabelled species). Compound-specific isotope analysis, where GC is interfaced to IRMS, is gaining popularity. Here, individual 13C-labelled compounds are separated by GC, combusted to CO2 and transferred on-line for ratiometric analysis by IRMS at the ppm level. However, commercially-available 13C-labelled retinol tracers are 2 - 4 times more expensive than deuterated tracers. For 2H-labelled compounds, GC-pyrolysis-IRMS has now become more generally available as an operating mode on the same IRMS instrument. Here, individual compounds are separated by GC and pyrolysed to H2 at high temperature for analysis by IRMS. It is predicted that GC-pyrolysis-IRMS will facilitate low level tracer procedures to measure body retinol stores, as has been accomplished in the case of fatty acids and amino acids. Sample size requirements for GC-P-IRMS may exceed those of GCMS, but this paper discusses sample preparation procedures and predicts improvements, particularly in the efficiency of sample introduction.

Isotope effects on the optical spectra of semiconductors

NASA Astrophysics Data System (ADS)

Cardona, Manuel; Thewalt, M. L. W.

2005-10-01

Since the end of the cold war, macroscopic amounts of separated stable isotopes of most elements have been available “off the shelf” at affordable prices. Using these materials, single crystals of many semiconductors have been grown and the dependence of their physical properties on isotopic composition has been investigated. The most conspicuous effects observed have to do with the dependence of phonon frequencies and linewidths on isotopic composition. These affect the electronic properties of solids through the mechanism of electron-phonon interaction, in particular, in the corresponding optical excitation spectra and energy gaps. This review contains a brief introduction to the history, availability, and characterization of stable isotopes, including their many applications in science and technology. It is followed by a concise discussion of the effects of isotopic composition on the vibrational spectra, including the influence of average isotopic masses and isotopic disorder on the phonons. The final sections deal with the effects of electron-phonon interaction on energy gaps, the concomitant effects on the luminescence spectra of free and bound excitons, with particular emphasis on silicon, and the effects of isotopic composition of the host material on the optical transitions between the bound states of hydrogenic impurities.

Evaporation loss and evaporation/transpiration partitioning from isotope-based monitoring of Canada's provincial and national river networks

NASA Astrophysics Data System (ADS)

Gibson, J. J.; Birks, S. J.; Stadnyk, T.; Delavau, C. J.

2017-12-01

Stable isotopes of water have been measured since the 1990's as part of hydrometric monitoring programs within Canada's Water Survey of Canada gauging network and Alberta's Long-Term River Network. These datasets are being applied for hydrograph separation of streamflow sources, including rain, snow, groundwater, and surface water, as well as for estimation of watershed evaporation losses and evaporation/transpiration partitioning. Here we describe an innovative isotope mass balance approach, discuss benefits and limitations of the method, and present selected results that illustrate important regional trends in the contemporary hydrology of Canada. Overall, isotopes are shown to be useful for constraining water balance variations across regions with low monitoring density. Recommendations for future activities are identified, including regional comparisons with outputs from isotope-capable distributed hydrologic models.

Isotopic investigation of rivers runoff in glaciated regions of the central Asian arid highlands (southeastern Altai)

NASA Astrophysics Data System (ADS)

Bantcev, Dmitrii; Ganushkin, Dmitriy; Ekaykin, Alexey; Chistyakov, Kirill

2017-04-01

Stable isotopes investigations were carried out during fieldwork in glacier basins of the Mongun-Taiga (southwestern Tuva) and Tsambagarav (northwestern Mongolia) mountain massifs in July, 2016. These Arid highlands are problematic in the context of provision of water resources, and glaciers here play a large part in nourishment of the rivers. Concentrations of the oxygen 18, deuterium and the mineralization were measured in the samples of meltwater, precipitation, water from streams, ice and snow. Sable isotope method was used for separation of the glacier runoff. Average isotopic characteristics for different water sources, such as glacier ice, snow patches and precipitation, were calculated and the contribution of these sources in total runoff was valued. Isotopic method was also used for estimation of contribution of buried ice meltwater from rock glaciers ice cores.

Equilibrium properties of dense hydrogen isotope gases based on the theory of simple fluids.

PubMed

Kowalczyk, Piotr; MacElroy, J M D

2006-08-03

We present a new method for the prediction of the equilibrium properties of dense gases containing hydrogen isotopes. The proposed approach combines the Feynman-Hibbs effective potential method and a deconvolution scheme introduced by Weeks et al. The resulting equations of state and the chemical potentials as functions of pressure for each of the hydrogen isotope gases depend on a single set of Lennard-Jones parameters. In addition to its simplicity, the proposed method with optimized Lennard-Jones potential parameters accurately describes the equilibrium properties of hydrogen isotope fluids in the regime of moderate temperatures and pressures. The present approach should find applications in the nonlocal density functional theory of inhomogeneous quantum fluids and should also be of particular relevance to hydrogen (clean energy) storage and to the separation of quantum isotopes by novel nanomaterials.

The TRIUMF nuclear structure program and TIGRESS

NASA Astrophysics Data System (ADS)

Garrett, P. E.; Andreyev, A.; Austin, R. A. E.; Ball, G. C.; Bandyopadhyay, D.; Becker, J. A.; Boston, A. J.; Boston, H. C.; Chakrawarthy, R. S.; Churchman, R.; Cline, D.; Cooper, R. J.; Cross, D.; Dashdorj, D.; Demand, G. A.; Dimmock, M. R.; Drake, T.; Finlay, P.; Gagnon, K.; Gallant, A. T.; Green, K. L.; Grint, A. N.; Grinyer, G. F.; Hackman, G.; Harkness, L. J.; Hayes, A. B.; Kanungo, R.; Kulp, W. D.; Leach, K. G.; Lee, G.; Leslie, J. R.; Maharaj, R.; Martin, J.-P.; Mattoon, C.; Mills, W. J.; Morton, A. C.; Nelson, L.; Newman, O.; Nolan, P. J.; Padilla-Rodal, E.; Pearson, C. J.; Phillips, A. A.; Porter-Peden, M.; Ressler, J. J.; Ruiz, C.; Sarazin, F.; Schumaker, M. A.; Scraggs, D. P.; Strange, M. D.; Subramanian, M.; Svensson, C. E.; Waddington, J. C.; Wan, J.; Whitbeck, A.; Williams, S. J.; Wood, J. L.; Wong, J. C.; Wu, C. Y.; Zganjar, E. F.

2007-08-01

The isotope separator and accelerator (ISAC) facility located at the TRIUMF laboratory in Vancouver, Canada, is one of the world's most advanced isotope separator on-line-type radioactive ion beam facilities. An extensive γ-ray spectroscopy programme at ISAC is centred around two major research facilities: (i) the 8π γ-ray spectrometer for β-delayed γ-ray spectroscopy experiments with the low-energy beams from ISAC-I, and (ii) the next generation TRIUMF-ISAC gamma-ray escape suppressed spectrometer (TIGRESS) for in-beam experiments with the accelerated radioactive-ion beams. An overview of these facilities and recent results from the diverse programme of nuclear structure and fundamental interaction studies they support is presented.

Photolytic separation of isotopes in cryogenic solution

DOEpatents

Freund, S.M.; Maier, W.B. II; Holland, R.F.; Battie, W.H.

Separation of carbon isotopes by photolysis of CS/sub 2/ in cryogenic solutions of nitrogen, krypton and argon with 206 nm light from an iodine resonance lamp is reported. The spectral distributionn of the ultraviolet absorption depends on solvent. Thus, in liquid nitrogen the photolytic decomposition rate of /sup 13/CS/sub 2/ is greater than that of /sup 12/CS/sub 2/ (because the absorption of 206 nm radiation is greater for /sup 13/CS/sub 2/), whereas in liquid krypton and liquid argon the reverse is true. The shift in ultraviolet spectrum is a general phenomenon readily characterized as a function of solvent polarizability, and exhibits behavior similar to that for vibrational transitions occurring in the infrared.

Photolytic separation of isotopes in cryogenic solution

DOEpatents

Freund, Samuel M.; Maier, II, William B.; Holland, Redus F.; Beattie, Willard H.

1985-01-01

Separation of carbon isotopes by photolysis of CS.sub.2 in cryogenic solutions of nitrogen, krypton and argon with 206 nm light from an iodine resonance lamp is reported. The spectral distribution of the ultraviolet absorption depends on solvent. Thus, in liquid nitrogen the photolytic decomposition rate of .sup.13 CS.sub.2 is greater than that of .sup.12 CS.sub.2 (because the absorption of 206 nm radiation is greater for .sup.13 CS.sub.2), whereas in liquid krypton and liquid argon the reverse is true. The shift in ultraviolet spectrum is a general phenomenon readily characterized as a function of solvent polarizability, and exhibits behavior similar to that for vibrational transitions occurring in the infrared.

High Precision Low-blank Lithium Isotope Ratios in Forams.

NASA Astrophysics Data System (ADS)

Misra, S.; Froelich, P. N.

2007-12-01

We present a high precision (±1‰, 2σ) low blank (<500 fg/ml) method for Li isotope measurements of forams using <2 ng of Li by single collector Quad ICP-MS (Agilent 7500cs). The Li isotope ratio of seawater (δ7Li) recorded in planktonic forams has the potential to constrain the evolution of seawater chemistry and elucidate the factors driving variations of oceanic mass balances linked to the continental and sea floor/hydrothermal silica cycles. In addition a δ7Li record of seawater will complement other long-term recorders of seawater chemistry such as Sr, Os and S isotopes. Li isotope measurements of forams are limited by several factors: low Li concentrations in forams (1-2 ppm), instrument-induced fractionation and mass bias effects, matrix effects, high Li blanks and incomplete recovery of Li during column separation. Modest concentrations of alkali and alkaline earth elements in the matrix result in variable mass bias in measured Li isotope ratios. Even worse, Li strongly fractionates during chromatographic clean-up to remove Na+, Ca2+ and Mg2+, from +100‰ in the leading edge to - 100‰ in the trailing edge of elution peaks (Urey 1938). Consequently, miniscule incomplete recoveries of Li during chromatographic separations can result in large unrecognized isotope fractionation of eluents. Large mass-dependent fractionation caused by a difference of 17% in mass between 6Li and 7Li, makes Li a powerful tracer of geochemical processes, but also promotes large and difficult-to-fix isotope fractionations during laboratory chemical processing. Matrix effects of Na & Ca and of column chromatography on Li isotope ratios were investigated using artificial Li solutions representative of foram compositions (matrix matching). Li/Ca and Li/Na ratios in cleaned forams are 10 μmol/mol and 3 mmol/mol respectively. An ICP-MS tolerance limit of 20 ppb for Na and 20 μM for Ca was established, much higher tolerances than by TIMS. A single step chromatographic method to quantitatively separate Li from matrix elements using both small volume resin (3.4 meq/2ml AG50W-X8) and acid (6 ml of 0.5N HCl) was developed. Our low blank (<0.5 pg/ml) and high yield (>99.99%) column method minimizes errors in measured Li isotope ratios associated with incomplete column recovery and presence of matrix elements. High sensitivity and precision achieved with a 7500cs using cold plasma (600W), soft extraction and peak jumping coupled with very low sample to blank ratios enables high precision (±1‰, 2σ) statistically significant Li isotope measurements using very small mass of Li (0.8 ng). The development of this technique makes possible good quality Li isotope measurements from samples that are mass limited for Li, i.e., reasonable number of picked forams. This will enable us to test interferences regarding chemical cleaning and species effects in planktonic forams along the road toward creating a δ7Li record of seawater for the Cenozoic.

A design study for a compact two stage in-flight separator with a high mass resolution and large acceptance

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hwang, Ji-Gwang; Kim, Eun-San, E-mail: eskim1@knu.ac.kr; Hatanaka, Kichiji

2015-03-15

The rare isotope beam separator with a large angular acceptance and energy acceptance is essential for examining the characteristics of unstable nuclei and exotic nuclear reactions. Careful design, however, is required to compensate for the effects of high order aberrations induced by large aperture magnets, which are used to collect rare isotopes obtained from a high energy primary heavy-ion beam hitting a target. In order to minimize the effect of the high order aberration, the optics was based on the mirror symmetry optics, which provides smaller high order aberrations, for the separation of {sup 132}Sn produced by a fission reactionmore » between the primary beam of {sup 238}U and a relatively thick Pb target. The designed optics provides energy acceptance (full), horizontal angular acceptance, and vertical acceptance of approximately 8%, 60 mrad, and 130 mrad, respectively.« less

A design study for a compact two stage in-flight separator with a high mass resolution and large acceptance.

PubMed

Hwang, Ji-Gwang; Kim, Eun-San; Hatanaka, Kichiji

2015-03-01

The rare isotope beam separator with a large angular acceptance and energy acceptance is essential for examining the characteristics of unstable nuclei and exotic nuclear reactions. Careful design, however, is required to compensate for the effects of high order aberrations induced by large aperture magnets, which are used to collect rare isotopes obtained from a high energy primary heavy-ion beam hitting a target. In order to minimize the effect of the high order aberration, the optics was based on the mirror symmetry optics, which provides smaller high order aberrations, for the separation of (132)Sn produced by a fission reaction between the primary beam of (238)U and a relatively thick Pb target. The designed optics provides energy acceptance (full), horizontal angular acceptance, and vertical acceptance of approximately 8%, 60 mrad, and 130 mrad, respectively.

A design study for a compact two stage in-flight separator with a high mass resolution and large acceptance

NASA Astrophysics Data System (ADS)

Hwang, Ji-Gwang; Kim, Eun-San; Hatanaka, Kichiji

2015-03-01

The rare isotope beam separator with a large angular acceptance and energy acceptance is essential for examining the characteristics of unstable nuclei and exotic nuclear reactions. Careful design, however, is required to compensate for the effects of high order aberrations induced by large aperture magnets, which are used to collect rare isotopes obtained from a high energy primary heavy-ion beam hitting a target. In order to minimize the effect of the high order aberration, the optics was based on the mirror symmetry optics, which provides smaller high order aberrations, for the separation of 132Sn produced by a fission reaction between the primary beam of 238U and a relatively thick Pb target. The designed optics provides energy acceptance (full), horizontal angular acceptance, and vertical acceptance of approximately 8%, 60 mrad, and 130 mrad, respectively.

Selective Hydrogen Isotope Separation via Breathing Transition in MIL-53(Al).

PubMed

Kim, Jin Yeong; Zhang, Linda; Balderas-Xicohténcatl, Rafael; Park, Jaewoo; Hirscher, Michael; Moon, Hoi Ri; Oh, Hyunchul

2017-12-13

Breathing of MIL-53(Al), a flexible metal-organic framework (MOF), leads to dynamic changes as narrow pore (np) transitions to large pore (lp). During the flexible and reversible transition, the pore apertures are continuously adjusted, thus providing the tremendous opportunity to separate mixtures of similar-sized and similar-shaped molecules that require precise pore tuning. Herein, for the first time, we report a strategy for effectively separating hydrogen isotopes through the dynamic pore change during the breathing of MIL-53(Al), a representative of flexible MOFs. The experiment shows that the selectivity for D 2 over H 2 is strongly related to the state of the pore structure of MIL-53(Al). The highest selectivity (S D 2 /H 2 = 13.6 at 40 K) was obtained by optimizing the exposure temperature, pressure, and time to systematically tune the pore state of MIL-53(Al).

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

Progress in the fields of nuclear chemistry, isolation and chemical properties of synthetic elements, chemical separation of isotopes, radiation chemistry, organic chemistry, chemistry of aquecus systems, electrochemistry of corrosion, nonaqueous systems at high temperature, and chemical physics for the year ending June 20, 1961, is reported. Separate abstracts were prepared for each topic. (M.C.G.)

A new geochemical instrument for the precise measurement of isotopic ratios and trace species in planetary atmospheres

NASA Astrophysics Data System (ADS)

Chassefiere, E.; Jambon, A.; Berthelier, J.-J.; Sarda, Ph.; Agrinier, P.

2003-04-01

The technique of GCMS analysis, which has been used with a great success on several past planetary missions, is not adapted for precise measurements of the isotopic composition of planetary atmospheres (noble gases, stable isotopes), and volatile outgassed products from solid sample pyrolysis. Static mass spectrometry, coupled with gas separation by cryo-separation, and chemical trapping, is commonly used in the laboratory to study volatiles extracted from terrestrial and meteoritic samples. This technique allows to reach a precision on isotopic ratios of the order of a few 0.1 ppm for a typical amount of gas of a few micromoles. We are presently studying an instrument based on the same principle for space exploration applications. The PALOMA instrument (PAyload for Local Observation of Mars Atmosphere) will be proposed in response to the AO for the instrumentation of the NASA Mars Smart Lander mission, planned to be launched in 2009. It might be part as well of the EXOMARS mission presently studied at ESA in the frame of the Aurora program. The miniaturization of major key elements, like the cryogenic device, the mass spectrometer, the line and its ensemble of valves, is presently led in our laboratories under CNES funding. The instrument consists of : (i) a gas purification and separation line, using techniques of cryogenic and chemical trapping, and possibly membrane permeation for molecular hydrogen analysis, (ii) a mass spectrometer working in static mode, without carrier gas (both time-of-flight and magnetic solutions are studied), (iii) a turbo-molecular pump that provides the required level of vacuum in the separation line and in the spectrometer. In the specific case of Mars, it is designed to work during typically 2 years (about 1000 measurement cycles), in order to perform accurate measurements of molecular, elemental and isotopic composition and of their diurnal/seasonal variations. The gas is sampled directly from the ambient atmosphere, without need for an external sample distribution system. The general characteristics of the instrument are as following . The mass is 6 kg, for a size of 30 x 30 x 20 cm. The required power, averaged over a complete measurement cycle, is 20 W (peak value : 30 W). The total energy required for one sequence is 100 Wh. This number must be considered as an upper limit, and corresponds to the most complex sequence (noble gas isotope analysis). Sequences used for stable isotopes measurement, and atmospheric molecular composition (trace gases of geological and/or astrobiological interest), are expected to be simpler, and less power-consuming. The anticipated volume of data produced by one observation sequence is estimated to be in the 3-6 kb range. The gas is sampled directly from the ambient atmosphere.

Structural and spectroscopic characterization of various isotopologues of 2-hydroxyacetonitrile using highly correlated ab initio methods

NASA Astrophysics Data System (ADS)

Dalbouha, Samira; Domínguez-Gómez, Rosa M.; Senent, Maria Luisa

2017-06-01

Various isotopologues of 2-hydroxyacetonitrile (OHCH2CN), a detectable astrophysical molecule, are characterized using explicitly correlated coupled cluster theory (CCSD(T)-F12/AVTZ-F12). Rovibrational parameters and far infrared transitions are computed to help the interpretation of the rotational spectra and radioastronomical observations. OHCH2CN displays non-rigid properties. The OH internal rotation intertransforms two conformers, gauche and trans, whose energy separation reaches 1.41 kcal/mol. The process is restricted by energy barriers of V t = 645 cm-1 and V g → g = 425 cm-1. Isotopic effects on the rotational constants and on the torsional energy levels are evaluated for isotopic varieties containing the most abundant cosmological isotopes (13C, 18C, 15N and D). Effects are relevant for ODCH2CN where the ground vibrational state splits in two components separated by 0.51 cm-1. This gap has been evaluated to be 3.20 cm-1 for the main isotopologue.

The SPES High Power ISOL production target

NASA Astrophysics Data System (ADS)

Andrighetto, A.; Corradetti, S.; Ballan, M.; Borgna, F.; Manzolaro, M.; Scarpa, D.; Monetti, A.; Rossignoli, M.; Silingardi, R.; Mozzi, A.; Vivian, G.; Boratto, E.; De Ruvo, L.; Sattin, N.; Meneghetti, G.; Oboe, R.; Guerzoni, M.; Margotti, A.; Ferrari, M.; Zenoni, A.; Prete, G.

2016-11-01

SPES (Selective Production of Exotic Species) is a facility under construction at INFN-LNL (Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Legnaro), aimed to produce intense neutron-rich radioactive ion beams (RIBs). These will be obtained using the ISOL (Isotope Separation On-Line) method, bombarding a uranium carbide target with a proton beam of 40MeV energy and currents up to 200μA. The target configuration was designed to obtain a high number of fissions, up to 1013 per second, low power deposition and fast release of the produced isotopes. The exotic isotopes generated in the target are ionized, mass separated and re-accelerated by the ALPI superconducting LINAC at energies of 10AMeV and higher, for masses in the region of A = 130 amu , with an expected rate on the secondary target up to 109 particles per second. In this work, recent results on the R&D activities regarding the SPES RIB production target-ion source system are reported.

Tracing the pathways of neotropical migratory shorebirds using stable isotopes: a pilot study.

PubMed

Farmer, A; Rye, R; Landis, G; Bern, C; Kester, C; Ridley, I

2003-09-01

We evaluated the potential use of stable isotopes to establish linkages between the wintering grounds and the breeding grounds of the Pectoral Sandpiper (Calidris melanotos), the White-rumped Sandpiper (Calidris fuscicollis), the Baird's Sandpiper (Calidris bairdii), and other Neotropical migratory shorebird species (e.g., Tringa spp.). These species molt their flight feathers on the wintering grounds and hence their flight feathers carry chemical signatures that are characteristic of their winter habitat. The objective of our pilot study was to assess the feasibility of identifying the winter origin of individual birds by: (1) collecting shorebird flight feathers from several widely separated Argentine sites and analyzing these for a suite of stable isotopes; and 2) analyzing the deuterium and 18O isotope data that were available from precipitation measurement stations in Argentina. Isotopic ratios (delta13C, delta15N and delta34S) of flight feathers were significantly different among three widely separated sites in Argentina during January 2001. In terms of relative importance in separating the sites, delta34S was most important, followed by delta15N, and then delta13C. In the complete discriminant analysis, the classification function correctly predicted group membership in 85% of the cases (jackknifed classification matrix). In a stepwise analysis delta13C was dropped from the solution, and site membership was correctly predicted in 92% of cases (jackknifed matrix). Analysis of precipitation data showed that both deltaD and delta18O were significantly related to both latitude and longitude on a countrywide scale (p < 0.001). Other variables, month, altitude, explained little additional variation in these isotope ratios. Several issues were identified that will likely constrain the degree of accuracy one can expect in predicting the geographic origin of birds from Argentina. There was unexplained variation in isotope ratios within and among the different wing feathers from individual birds. Such variation may indicate that birds are not faithful to a local site during their winter stay in Argentina. There was significant interannual variation in the deltaD and delta18O of precipitation. Hence, specific locations may not have a constant signature for some isotopes. Moreover, the fractionation that occurs in wetlands due to evaporation significantly skews local deltaD and delta18O values, which may undermine the strong large-scale gradients seen in the precipitation data. We are continuing the research with universities in Argentina with a focus on expanding the breadth of feather collection and attempting to resolve the identified issues.

Tracing the pathways of Neotropical migratory shorebirds using stable isotopes: A pilot study

USGS Publications Warehouse

Farmer, A.H.; Rye, R.; Landis, G.; Bern, C.; Kester, C.; Ridley, I.

2003-01-01

We evaluated the potential use of stable isotopes to establish linkages between the wintering grounds and the breeding grounds of the Pectoral Sandpiper (Calidris melanotos), the White-rumped Sandpiper (Calidris fuscicollis), the Baird's Sandpiper (Calidris bairdii), and other Neotropical migratory shorebird species (e.g., Tringa spp.). These species molt their flight feathers on the wintering grounds and hence their flight feathers carry chemical signatures that are characteristic of their winter habitat. The objective of our pilot study was to assess the feasibility of identifying the winter origin of individual birds by: (1) collecting shorebird flight feathers from several widely separated Argentine sites and analyzing these for a suite of stable isotopes; and (2) analyzing the deuterium and 18O isotope data that were available from precipitation measurement stations in Argentina. Isotopic ratios (δ13C, δ15N and δ34S) of flight feathers were significantly different among three widely separated sites in Argentina during January 2001. In terms of relative importance in separating the sites, δ34S was most important, followed by δ15N, and then δ13C. In the complete discriminant analysis, the classification function correctly predicted group membership in 85% of the cases (jackknifed classification matrix). In a stepwise analysis δ13C was dropped from the solution, and site membership was correctly predicted in 92% of cases (jackknifed matrix). Analysis of precipitation data showed that both δD and δ18O were significantly related to both latitude and longitude on a countrywide scale (p < 0.001). Other variables, month, altitude, explained little additional variation in these isotope ratios. Several issues were identified that will likely constrain the degree of accuracy one can expect in predicting the geographic origin of birds from Argentina. There was unexplained variation in isotope ratios within and among the different wing feathers from individual birds. Such variation may indicate that birds are not faithful to a local site during their winter stay in Argentina. There was significant interannual variation in the δD and δ18O of precipitation. Hence, specific locations may not have a constant signature for some isotopes. Moreover, the fractionation that occurs in wetlands due to evaporation significantly skews local δD and δ18O values, which may undermine the strong large-scale gradients seen in the precipitation data. We are continuing the research with universities in Argentina with a focus on expanding the breadth of feather collection and attempting to resolve the identified issues.

Late metal-silicate separation on the IAB parent asteroid: Constraints from combined W and Pt isotopes and thermal modelling

NASA Astrophysics Data System (ADS)

Hunt, Alison C.; Cook, David L.; Lichtenberg, Tim; Reger, Philip M.; Ek, Mattias; Golabek, Gregor J.; Schönbächler, Maria

2018-01-01

The short-lived 182Hf-182W decay system is a powerful chronometer for constraining the timing of metal-silicate separation and core formation in planetesimals and planets. Neutron capture effects on W isotopes, however, significantly hamper the application of this tool. In order to correct for neutron capture effects, Pt isotopes have emerged as a reliable in-situ neutron dosimeter. This study applies this method to IAB iron meteorites, in order to constrain the timing of metal segregation on the IAB parent body. The ε182W values obtained for the IAB iron meteorites range from -3.61 ± 0.10 to -2.73 ± 0.09. Correlating εiPt with ε182W data yields a pre-neutron capture ε182W of -2.90 ± 0.06. This corresponds to a metal-silicate separation age of 6.0 ± 0.8 Ma after CAI for the IAB parent body, and is interpreted to represent a body-wide melting event. Later, between 10 and 14 Ma after CAI, an impact led to a catastrophic break-up and subsequent reassembly of the parent body. Thermal models of the interior evolution that are consistent with these estimates suggest that the IAB parent body underwent metal-silicate separation as a result of internal heating by short-lived radionuclides and accreted at around 1.4 ± 0.1 Ma after CAIs with a radius of greater than 60 km.

Overview of the ISOL facility for the RISP

NASA Astrophysics Data System (ADS)

Woo, H. J.; Kang, B. H.; Tshoo, K.; Seo, C. S.; Hwang, W.; Park, Y.-H.; Yoon, J. W.; Yoo, S. H.; Kim, Y. K.; Jang, D. Y.

2015-02-01

The key feature of the Isotope Separation On-Line (ISOL) facility is its ability to provide high-intensity and high-quality beams of neutron-rich isotopes with masses in the range of 80-160 by means of a 70-MeV proton beam directly impinging on uranium-carbide thin-disc targets to perform forefront research in nuclear structure, nuclear astrophysics, reaction dynamics and interdisciplinary fields like medical, biological and material sciences. The technical design of the 10-kW and the 35-kW direct fission targets with in-target fission rates of up to 1014 fissions/s has been finished, and for the development of the ISOL fission-target chemistry an initial effort has been made to produce porous lanthanum-carbide (LaCx) discs as a benchmark for the final production of porous UCx discs. For the production of various beams, three classes of ion sources are under development at RISP (Rare Isotope Science Project), the surface ion source, the plasma ion source (FEBIAD), the laser ion source, and the engineering design of the FEBIAD is in progress for prototype fabrication. The engineering design of the ISOL target/ion source front-end system is also in progress, and a prototype will be used for an off-line test facility in front of the pre-separator. The technical designs of other basic elements at the ISOL facility, such as the RF-cooler, the high-resolution mass separator, and the A/q separator, have been finished, and the results, along with the future plans, are introduced.

Recognizing and overcoming analytical error in the use of ICP-MS for the determination of cadmium in breakfast cereal and dietary supplements.

PubMed

Murphy, Karen E; Vetter, Thomas W

2013-05-01

The potential effect of spectral interference on the accurate measurement of the cadmium (Cd) mass fraction in fortified breakfast cereal and a variety of dietary supplement materials using inductively coupled plasma quadrupole mass spectrometry was studied. The materials were two new standard reference materials (SRMs)--SRM 3233 Fortified Breakfast Cereal and SRM 3532 Calcium Dietary Supplement--as well as several existing materials--SRM 3258 Bitter Orange Fruit, SRM 3259 Bitter Orange Extract, SRM 3260 Bitter Orange-containing Solid Oral Dosage Form, and SRM 3280 Multivitamin/Multielement Tablets. Samples were prepared for analysis using the method of isotope dilution and measured using various operating and sample introduction configurations including standard mode, collision cell with kinetic energy discrimination mode, and standard mode with sample introduction via a desolvating nebulizer system. Three isotope pairs, (112)Cd/(111)Cd, (113)Cd/(111)Cd, and (114)Cd/(111)Cd, were measured. Cadmium mass fraction results for the unseparated samples of each material, measured using the three instrument configurations and isotope pairs, were compared to the results obtained after the matrix was removed via chemical separation using anion exchange chromatography. In four of the six materials studied, measurements using the standard mode with sample introduction via the desolvating nebulizer gave results for the unseparated samples quantified with the (112)Cd/(111)Cd isotope pair that showed a positive bias relative to the matrix-separated samples, which indicated a persistent inference at m/z112 with this configuration. Use of the standard mode, without the desolvating nebulizer, also gave results that showed a positive bias for the unseparated samples quantified with the (112)Cd/(111)Cd isotope pair in three of the materials studied. Collision cell/kinetic energy discrimination mode, however, was very effective for reducing spectral interference for Cd in all of the materials and isotope pairs studied, except in the multivitamin/multielement matrix (SRM 3280) where the large corrections for known isobaric interferences or unidentified interferences compromised the accuracy. For SRM 3280, matrix separation provided the best method to achieve accurate measurement of Cd.

Determination of (87)Sr/(86)Sr and δ(88/86)Sr ratios in plant materials using MC-ICP-MS.

PubMed

Liu, Hou-Chun; Chung, Chuan-Hsiung; You, Chen-Feng; Chiang, Yi-Hsuan

2016-01-01

A protocol for highly accurate and precise determination of Sr isotope ratios in plant materials, (87)Sr/(86)Sr and δ (88/86)Sr, by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) is presented in this study. An Eichrom Sr resin was used for matrix separation and an improved Zr empirical external normalization coupled with standard-sample bracketing method (Zr EEN-SSB) was applied to mass bias correction during Sr isotope MC-ICP-MS measurements. Potential influences of matrix elements, and polyatomic and isobaric interferences on the Sr isotopic determination were further evaluated using NIST SRM 987 Sr isotopic standard spiked with various amount of Ca, Mg, and Rb contents. Concentrations of Ca and Mg lower than 30 ng g(-1) or Rb < 2 ng g(-1) in 150 ng g(-1) Sr analyte were estimated to have only a minor effect on Sr isotope ratios determination. On the other hand, intensity differences between sample and standards (IntSample/IntStandards) represented a large δ (88/86)Sr deviation of <0.9 or >1.3, reflecting the significance of intensity bias attributed to different mass bias behavior. An apple leaf material, NIST SRM 1515, was adopted as the plant material for overall evaluation of sample digestion, matrix separation, and potential spectral interferences on the measurements of Sr isotope ratios. Our results suggest that the partially remaining organic compounds in the incomplete digestion would have a significant bias on the extraction chromatography procedure, resulting in sizable uncertainty in δ (88/86)Sr ratios. Thus, complete digestion of the organic-enriched materials is of great importance for efficiency assurance in matrix separation. Extraction chromatography works well for the total digested samples, where Ca, Mg, and Rb were efficiently removed. The obtained average (87)Sr/(86)Sr and δ (88/86)Sr values for the NIST SRM 1515 apple leaves are 0.71398 ± 0.00004 and 0.23 ± 0.03‰ (2SD, n = 10), respectively.

Chemical resolution of Pu+ from U+ and Am+ using a band-pass reaction cell inductively coupled plasma mass spectrometer.

PubMed

Tanner, Scott D; Li, Chunsheng; Vais, Vladimir; Baranov, Vladimir I; Bandura, Dmitry R

2004-06-01

Determination of the concentration and distribution of the Pu and Am isotopes is hindered by the isobaric overlaps between the elements themselves and U, generally requiring time-consuming chemical separation of the elements. A method is described in which chemical resolution of the elemental ions is obtained through ion-molecule reactions in a reaction cell of an ICPMS instrument. The reactions of "natural" U(+), (242)Pu(+), and (243)Am(+) with ethylene, carbon dioxide, and nitric oxide are reported. Since the net sensitivities to the isotopes of an element are similar, chemical resolution is inferred when one isobaric element reacts rapidly with a given gas and the isobar (or in this instance surrogate isotope) is unreactive or slowly reactive. Chemical resolution of the m/z 238 isotopes of U and Pu can be obtained using ethylene as a reaction gas, but little improvement in the resolution of the m/z 239 isobars is obtained. However, high efficiency of reaction of U(+) and UH(+) with CO(2), and nonreaction of Pu(+), allows the sub-ppt determination of (239)Pu, (240)Pu, and (242)Pu (single ppt for (238)Pu) in the presence of 7 orders of magnitude excess U matrix without prior chemical separation. Similarly, oxidation of Pu(+) by NO, and nonreaction of Am(+), permit chemical resolution of the isobars of Pu and Am over 2-3 orders of magnitude relative concentration. The method provides the potential for analysis of the actinides with reduced sample matrix separation.

Precision mass measurements of cesium isotopes—new entries in the ISOLTRAP chronicles

NASA Astrophysics Data System (ADS)

Atanasov, D.; Beck, D.; Blaum, K.; Borgmann, Ch; Cakirli, R. B.; Eronen, T.; George, S.; Herfurth, F.; Herlert, A.; Kowalska, M.; Kreim, S.; Litvinov, Yu A.; Lunney, D.; Manea, V.; Neidherr, D.; Rosenbusch, M.; Schweikhard, L.; Wienholtz, F.; Wolf, R. N.; Zuber, K.

2017-04-01

Alkali ion beams are among the most intense produced by the ISOLDE facility. These were the first to be studied by the ISOLTRAP mass spectrometer and ever since, new measurements have been regularly reported. Recently the masses of very neutron-rich and short-lived cesium isotopes were determined at ISOLTRAP. The isotope 148Cs was measured directly for the first time by Penning-trap mass spectrometry. Using the new results, the trend of two-neutron separation energies in the cesium isotopic chain is revealed to be smooth and gradually decreasing, similar to the ones of the barium and xenon isotopic chains. Predictions of selected microscopic models are employed for a discussion of the experimental data in the region.

Decay of the neutron-rich isotope 171Ho and the identification of 169Dy

NASA Astrophysics Data System (ADS)

Chasteler, R. M.; Nitschke, J. M.; Firestone, R. B.; Vierinen, K. S.; Wilmarth, P. A.

1990-10-01

Neutron-rich rare-earth isotopes were produced in multinucleon transfer reactions between 170Er ions and natW targets. On-line mass separation was used together with β- and γ-ray spectroscopy in these studies. At mass A=169, the heaviest known dysprosium isotope, 39(8) s,169Dy, was identified. It was observed to β- decay to the ground state of 169Ho or through a level at 1578 keV. In the A=171 mass chain, a partial decay scheme for 55(3)-s 171Ho was determined.

Analytical Chemistry Developmental Work Using a 243Am Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spencer, Khalil J.; Stanley, Floyd E.; Porterfield, Donivan R.

2015-02-24

This project seeks to reestablish our analytical capability to characterize Am bulk material and develop a reference material suitable to characterizing the purity and assay of 241Am oxide for industrial use. The tasks associated with this phase of the project included conducting initial separations experiments, developing thermal ionization mass spectrometry capability using the 243Am isotope as an isotope dilution spike , optimizing the spike for the determination of 241Pu- 241 Am radiochemistry, and, additionally, developing and testing a methodology which can detect trace to ultra- trace levels of Pu (both assay and isotopics) in bulk Am samples .

Applicability of Separation Potentials to Determining the Parameters of Cascade Efficiency in Enrichment of Ternary Mixtures

NASA Astrophysics Data System (ADS)

Palkin, V. A.; Igoshin, I. S.

2017-01-01

The separation potentials suggested by various researchers for separating multicomponent isotopic mixtures are considered. An estimation of their applicability to determining the parameters of the efficiency of enrichment of a ternary mixture in a cascade with an optimum scheme of connection of stages made up of elements with three takeoffs is carried out. The separation potential most precisely characterizing the separative power and other efficiency parameters of stages and cascade schemes has been selected based on the results of the estimation made.

Separation of Bismuth from Lead with (Ethylenediamine)tetraacetic Acid. Application to Radiochemistry; SEPARACAO DE BISMUTO DO CHUMBO COM ACIDO ETILENODIAMINOTETRAACETICO APLICACAO PARA RADIOQUIMICA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lima, F.W.; Abrao, A.

1958-09-01

Bismuth can be separated from lead radiochemically by using (ethylenediamine)tetraacetic acid. The separation is successful when both elements are in trace concentration when one is in trace concentrations and other in macroconcentrations, and when both are in macroconcentrations. A single separation gives more than 90% of both elements. The process involves simple manipulations and can be done in less than fifteen minutes, which is of importance in the separation of short-lived isotopes. (tr-auth)

Neodymium and strontium isotopic dating of diagenesis and low-grade metamorphism of argillaceous sediments

NASA Astrophysics Data System (ADS)

Schaltegger, Urs; Stille, Peter; Rais, Naoual; Piqué, Alain; Clauer, Norbert

1994-03-01

The behaviour of the Rb-Sr and Sm-Nd isotopic systems with increasing degree of Hercynian metamorphic overprint was studied along a transect in Cambrian shales of northwestern Morocco. Clay fractions of < 0.2 to 2-6 μm size from five samples were investigated, representing a range from nonmetamorphic to epizonal metamorphic conditions. The samples were washed in cold l N HC1 prior to digestion to separate soluble/exchangeable Rb, Sr, Sm, and Nd from amounts of these elements fixed in the crystallographic sites of the minerals and to analyze both components separately. The results reveal that the Rb-Sr isotopic system is dominated by Sr hosted by clay mineral phases (both detrital and authigenic illite and chlorite) and carbonate-hosted soluble Sr. Isotopic homogenization of Sr occurred during Hercynian metamorphism, yielding ages between 309 and 349 Ma. The Sm-Nd isotopic system, on the other hand, is dominated by cogenetic apatite and Fe oxide/ hydroxide, both having high contents of leachable REEs. The leachates yield a Sm-Nd isochron age of 523 ± 72 Ma, indicating diagenetic equilibrium between apatite and Fe-oxide/hydroxide. Fine-grained clay fractions of < 0.2 μm size plot onto this reference line, suggesting isotopic equilibrium with the leachates. Size fractions > 0.2 μm show inheritance of a detrital Nd component. The study demonstrates that the diagenesis of the investigated argillaceous sediments can be dated by the Sm-Nd chronometer in authigenic cement phases. The isotopic system of these minerals (apatite, Fe hydroxide/oxide) was homogenized during authigenic mineral growth in a sediment that was flushed by diagenetic fluids and had abundant primary or secondary interconnected pore space. The Hercynian metamorphic overprint caused partial isotopic rehomogenization of the adsorbed and clay-hosted portion of the Sr as well as of the carbonate-hosted Sr. The Sm-Nd system in the cement phases survived this metamorphism. This results in decoupling of the two isotopic systems and allows the dating of diagenesis on the one hand (Sm-Nd) and metamorphism on the other hand (Rb-Sr).

Core formation conditons in planetesimals: constraints from isotope fractionation experiments.

NASA Astrophysics Data System (ADS)

Guignard, J.; Quitté, G.; Toplis, M. J.; Poitrasson, F.

2016-12-01

Planetesimals are small objects (10 to 1000 km) early accreted in the history of the solar system which show a wide variety of thermal history due to the initial amount of radiogenic elements [1] (26Al and 60Fe), from a simple metamorphism to a complete metal-silicate differentiation. Moreover, isotope compositions of siderophile element, e.g. Fe, Ni, and W in meteorites spread on a range that can be attributed to the process of core-mantle segregation. We therefore performed isotope fractionation experiments of nickel and tungsten between metal and silicate in a gas-mixing (CO-CO2) vertical furnace, at different temperatures (from 1270°C to 1600°C), oxygen fugacity (from IW+2 to IW-6) and annealing times (from 20 minutes to 48 hours). The starting silicate is an anorthite-diopside eutectic composition glass, synthesize from the respective oxides. The starting metal is either a nickel or tungsten wire according to the element to study. After each experiment, metal and silicate are mechanically separated and digested in acids. Nickel and Tungsten separation have been made according to the methods developed by [2] and [3] and isotopes measurements have been made using a high resolution MC-ICP-MS (Neptune; Thermofisher©). Results show evidence for a strong kinetic isotope fractionation during the first annealing times with a faster diffusion of lightest isotopes than heaviest. Similar mechanism has been already highlighted for iron isotope fractionation between silicate and metal [4]. Chemical and isotopic equilibrium is also reached in our experiments but the time required dependent on the conditions of temperature and oxygen fugacity. Therefore, at equilibrium, metal-silicate isotope fractionation has also been quantified as well its temperature dependence. These experimental data can be used in order to bring new constraints on the metal silicate segregation in the planetesimals early accreted. [1] Lee T., et al., GRL, 3, 41-44 (1976) [2] Quitté G., and Oberli F., JAAS, 21, 1249-1255 (2006) [3] Breton T., and Quitté G., JAAS, 29, 2284-2293 (2014) [4] Roskosz M., et al., EPSL, 248, 851-867 (2006)

New insight from noble gas and stable isotopes of geothermal/hydrothermal fluids at Caviahue-Copahue Volcanic Complex: Boiling steam separation and water-rock interaction at shallow depth

NASA Astrophysics Data System (ADS)

Roulleau, Emilie; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; Vinet, Nicolas; Bravo, Francisco; Muñoz, Carlos; Sanchez, Juan

2016-12-01

We measured noble gas and stable isotopes of the geothermal and hydrothermal fluids of the Caviahue-Copahue Volcanic Complex (CCVC), one of the most important geothermal systems in Argentina/Chile, in order to provide new insights into fluid circulation and origin. With the exception of Anfiteatro and Chancho-co geothermal systems, mantle-derived helium dominates in the CCVC fluids, with measured 3He/4He ratios up to 7.86Ra in 2015. Their positive δ15N is an evidence for subducted sediment-derived nitrogen, which is commonly observed in subduction settings. Both He-N2-Ar composition and positive correlation between δD-H2O and δ18O-H2O suggest that the fluids from Anfiteatro and Chancho-co (and partly from Pucon-Mahuida as well, on the southern flank of Copahue volcano) represent a meteoric water composition with a minor magmatic contribution. The Ne, Kr and Xe isotopic compositions are entirely of atmospheric origin, but processes of boiling and steam separation have led to fractionation of their elemental abundances. We modeled the CCVC fluid evolution using Rayleigh distillation curves, considering an initial air saturated geothermal water (ASGW) end-member at 250 and 300 °C, followed by boiling and steam separation at lower temperatures (from 200 °C to 150 °C). Between 2014 and 2015, the CCVC hydrogen and oxygen isotopes shifted from local meteoric water-dominated to andesitic water-dominated signature. This shift is associated with an increase of δ13C values and Stotal, HCl and He contents. These characteristics are consistent with a change in the gas ascent pathway between 2014 and 2015, which in turn induced higher magmatic-hydrothermal contribution in the fluid signature. The composition of the magmatic source of the CCVC fluids is: 3He/4He = 7.7Ra, δ15N = + 6‰, and δ13C = - 6.5‰. Mixing models between air-corrected He and N suggest the involvement of 0.5% to 5% of subducted sediments in the magmatic source. The magmatic sulfur isotopic composition is estimated at - 2.38‰ (from COP-2), but most samples show elemental fractionation due to boiling and steam separation followed by various degrees of atmospheric contamination. All these geochemical and isotopic characteristics are the direct consequence of tectonic particularities of the CCVC: NE faults promote the ascent of hydrothermal fluids in the geothermal area whereas WNW faults serve as preferential channels for meteoric water infiltration.

A Procedure to Simultaneously Determine the Calcium, Chromium, and Titanium Isotopic Compositions of Astromaterials

NASA Technical Reports Server (NTRS)

Tappa, M. J.; Simon, J. I; Jordan, M. K.; Young, E. D.

2015-01-01

Many elements display both linear (mass-dependent) and non-linear (mass-independent) isotope anomalies (relative to a common reservoir). In early Solar System objects, with the exception of oxygen, mass-dependent isotope anomalies are most commonly thought to result from phase separation processes such as evaporation and condensation, whereas many mass-independent isotope anomalies likely reflect radiogenic ingrowth or incomplete mixing of presolar components in the proto-planetary disk. Coupling the isotopic characterization of multiple elements with differing volatilities in single objects may provide information regarding the location, source material, and/or processes involved in the formation of early Solar System solids. Here, we follow up on the work presented in, and detail new procedures developed to make high-precision multi-isotope measurements of Calcium, Chromium, and Titanium with small or limited amounts of sample using thermal ionization mass spectrometry and multi-collector ICP-MS, and characterize a suite of chondritic and terrestrial standards.

Highly tritiated water processing by isotopic exchange

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shu, W.M.; Willms, R.S.; Glugla, M.

2015-03-15

Highly tritiated water (HTW) is produced in fusion machines and one of the promising technologies to process it is isotopic exchange. 3 kinds of Pt-catalyzed zeolite (13X-APG, CBV-100-CY and HiSiv-1000) were tested as candidates for isotopic exchange of highly tritiated water (HTW), and CBV-100-CY (Na-Y type with a SiO{sub 2}/Al{sub 2}O{sub 3} ratio of ∼ 5.0) shows the best performance. Small-scale tritium testing indicates that this method is efficient for reaching an exchange factor (EF) of 100. Full-scale non-tritium testing implies that an EF of 300 can be achieved in 24 hours of operation if a temperature gradient is appliedmore » along the column. For the isotopic exchange, deuterium recycled from the Isotope Separation System (deuterium with 1% T and/or 200 ppm T) should be employed, and the tritiated water regenerated from the Pt-catalyzed zeolite bed after isotopic exchange should be transferred to Water Detritiation System (WDS) for further processing.« less

METHOD FOR PRODUCING ISOTOPIC METHANES FROM LITHIUM CARBONATE AND LITHIUM HYDRIDE

DOEpatents

Frazer, J.W.

1959-10-27

A process is descrlbed for the production of methane and for the production of methane containing isotopes of hydrogen and/or carbon. Finely divided lithium hydrlde and litldum carbonate reactants are mixed in intimate contact and subsequently compacted under pressures of from 5000 to 60,000 psl. The compacted lithium hydride and lithium carbenate reactunts are dispised in a gas collecting apparatus. Subsequently, the compact is heated to a temperature in the range 350 to 400 deg C whereupon a solid-solid reaction takes place and gaseous methane is evolved. The evolved methane is contaminated with gaseous hydrogen and a very small amount of CO/sub 2/; however, the desired methane product is separated from sald impurities by well known chemical processes, e.g., condensation in a cold trap. The product methane contalns isotopes of carbon and hydrogen, the Isotopic composition being determined by the carbon isotopes originally present In the lithium carbonate and the hydrogen isotopes originally present in the lithium hydride.

Gaseous isotope separation using solar wind phenomena.

PubMed

Wang, C G

1980-12-01

A large evacuated drum-like chamber fitted with supersonic nozzles in the center, with the chamber and the nozzles corotating, can separate gaseous fluids according to their molecular weights. The principle of separation is essentially the same as that of the solar wind propagation, in which components of the plasma fluid are separated due to their difference in the time-of-flight. The process can inherently be very efficient, serving as a pump as well as a separator, and producing well over 10(5) separative work units (kg/year) for the hydrogen/deuterium mixture at high-velocity flows.

Beam optical design of in-flight fragment separator for high-power heavy ion beam

NASA Astrophysics Data System (ADS)

Yun, C. C.; Kim, Mi-Jung; Kim, D. G.; Song, J. S.; Kim, Myeong-Jin; Kim, J. W.; Kim, J. R.; Wan, W.

2013-12-01

An in-flight fragment separator has been designed for the rare isotope science project (RISP) in Korea. A beam used for the design is 238U in the energy of 200 MeV/u with the maximum beam power of 400 kW. The use of high-power beam requires careful removal of the primary beam by pre-separator, for which its configuration was revised to employ four dipole magnets instead of two. Different configurations of the separator have been tested in search of optimal design in non-linear optics, which was complicated by the space needed for the target, beam dump and radiation shielding. Non-linear optical calculations have been carried out using GICOSY and COSY Infinity including the fringe fields of large-aperture quadrupole magnets. Correction of non-linear terms is made with multipole coils located inside the superconducting quadrupole magnets and by external multipole magnets. Beam simulations using LISE++ and MOCADI have been performed to consider the effects of multiple charge states of the primary and isotope beams produced at the target. Layout of the separator is being finalized, and detailed optics simulation will continue to refine its design.

Protein Stable Isotope Fingerprinting (P-SIF): Multidimensional Protein Chromatography Coupled to Stable Isotope-Ratio Mass Spectrometry

NASA Astrophysics Data System (ADS)

Pearson, A.; Bovee, R. J.; Mohr, W.; Tang, T.

2012-12-01

As metagenomics increases our insight into microbial community diversity and metabolic potential, new approaches are required to determine the biogeochemical expression of this potential within ecosystems. Because stable isotopic analysis of the major bioactive elements (C, N) has been used historically to map flows of substrates and energy among macroscopic food webs, similar principles may apply to microbes. To address this challenge, we have developed a new analytical approach called Protein Stable Isotope Fingerprinting (P-SIF). P-SIF generates natural stable isotopic fingerprints of microbial individual or community proteomes. The main advantage of P-SIF is the potential to bridge the gap between diversity and function, thereby providing a window into the "black box" of environmental microbiology and helping to decipher the roles of uncultivated species. Our method implements a three-way, orthogonal scheme to separate mixtures of whole proteins into subfractions dominated by single or closely-related proteins. Protein extracts first are isoelectrically focused in a gel-free technique that yields 12 fractions separated over a gradient of pH 3-10. Each fraction then is separated by size-exclusion chromatography into 20 pools, ranging from >100kD to ~10kD. Finally, each of these pools is subjected to HPLC and collected in 40 time-slices based on protein hydrophobicity. Theoretical calculation reveals that the true chromatographic resolution of the total scheme is 5000, somewhat less than the 9600 resulting fractions. High-yielding fractions are subjected to δ13C analysis by spooling-wire microcombustion irMS (SWiM-irMS) optimized for samples containing 1-5 nmol carbon. Here we will present the method, results for a variety of pure cultures, and preliminary data for a sample of mixed environmental proteins. The data show the promise of this method for unraveling the metabolic complexity hidden within microbial communities.

Isotopic analyses of nitrogenous compounds from the Murchison meteorite: ammonia, amines, amino acids, and polar hydrocarbons

NASA Technical Reports Server (NTRS)

Pizzarello, S.; Feng, X.; Epstein, S.; Cronin, J. R.

1994-01-01

The combined volatile bases (ammonia, aliphatic amines, and possibly other bases), ammonia, amino acids, and polar hydrocarbons were prepared from the Murchison meteorite for isotopic analyses. The volatile bases were obtained by cryogenic transfer after acid-hydrolysis of a hot-water extract and analyzed by combined gas chromatography-mass spectrometry of pentafluoropropionyl derivatives. The aliphatic amines present in this preparation comprise a mixture that includes both primary and secondary isomers through C5 at a total concentration of > or = 100 nmoles g-1. As commonly observed for meteoritic organic compounds, almost all isomers through C5 are present, and the concentrations within homologous series decrease with increasing chain length. Ammonia was chromatographically separated from the other volatile bases and found at a concentration of 1.1-1.3 micromoles g-1 meteorite. The ammonia analyzed includes contributions from ammonium salts and the hydrolysis of extractable organic compounds, e.g., carboxamides. Stable isotope analyses showed the volatile bases to be substantially enriched in the heavier isotopes, relative to comparable terrestrial compounds delta D < or = +1221%; delta 13C = +22%; delta 15N = +93%). Ammonia, per se, was found to have a somewhat lower delta 15N value (+69%) than the total volatile bases; consequently, a higher delta 15N (>93%) can be inferred for the other bases, which include the amines. Solvent-extractable polar hydrocarbons obtained separately were found to be enriched in 15N (delta 15N = +104%). Total amino acids, prepared from a hydrolyzed hot-water extract by cation exchange chromatography, gave a delta 15N of +94%, a value in good agreement with that obtained previously. Nitrogen isotopic data are also given for amino acid fractions separated chromatographically. The delta 15N values of the Murchison soluble organic compounds analyzed to date fall within a rather narrow range (delta 15N = +94 +/- 8%), an observation consistent with their formation, or formation of their precursors, by interstellar chemistry.

EM reconstruction of dual isotope PET using staggered injections and prompt gamma positron emitters

PubMed Central

Andreyev, Andriy; Sitek, Arkadiusz; Celler, Anna

2014-01-01

Purpose: The aim of dual isotope positron emission tomography (DIPET) is to create two separate images of two coinjected PET radiotracers. DIPET shortens the duration of the study, reduces patient discomfort, and produces perfectly coregistered images compared to the case when two radiotracers would be imaged independently (sequential PET studies). Reconstruction of data from such simultaneous acquisition of two PET radiotracers is difficult because positron decay of any isotope creates only 511 keV photons; therefore, the isotopes cannot be differentiated based on the detected energy. Methods: Recently, the authors have proposed a DIPET technique that uses a combination of radiotracer A which is a pure positron emitter (such as 18F or 11C) and radiotracer B in which positron decay is accompanied by the emission of a high-energy (HE) prompt gamma (such as 38K or 60Cu). Events that are detected as triple coincidences of HE gammas with the corresponding two 511 keV photons allow the authors to identify the lines-of-response (LORs) of isotope B. These LORs are used to separate the two intertwined distributions, using a dedicated image reconstruction algorithm. In this work the authors propose a new version of the DIPET EM-based reconstruction algorithm that allows the authors to include an additional, independent estimate of radiotracer A distribution which may be obtained if radioisotopes are administered using a staggered injections method. In this work the method is tested on simple simulations of static PET acquisitions. Results: The authors’ experiments performed using Monte-Carlo simulations with static acquisitions demonstrate that the combined method provides better results (crosstalk errors decrease by up to 50%) than the positron-gamma DIPET method or staggered injections alone. Conclusions: The authors demonstrate that the authors’ new EM algorithm which combines information from triple coincidences with prompt gammas and staggered injections improves the accuracy of DIPET reconstructions for static acquisitions so they reach almost the benchmark level calculated for perfectly separated tracers. PMID:24506645

METHOD OF SEPARATING ISOTOPES OF URANIUM IN A CALUTRON

DOEpatents

Jenkins, F.A.

1958-05-01

Mass separation devices of the calutron type and the use of uranium hexachloride as a charge material in the calutron ion source are described. The method for using this material in a mass separator includes heating the uranium hexachloride to a temperature in the range of 60 to 100 d C in a vacuum and thereby forming a vapor of the material. The vaporized uranium hexachloride is then ionized in a vapor ionizing device for subsequent mass separation processing.

Re-Os isotopic systematics in chromitites from the Stillwater Complex, Montana, USA

NASA Astrophysics Data System (ADS)

Marcantonio, Franco; Zindler, Alan; Reisberg, Laurie; Mathez, E. A.

1993-08-01

New Re-Os isotopic data on chromitites of the Stillwater Complex demonstrate isotopic equilibrium between cumulate chromite and whole rock. Initial osmium isotopic ratios for the chromitites, chosen for their freshness, are consistent with derivation from a mantle-derived magma that suffered little or no interaction with the continental crust prior to crystallization. Molybdenite, separated from a sample of the G-chromitite, yields a Re-Os age of 2740 Ma, indistinguishable from the age of the intrusion. The presence of molybdenite documents rhenium, and probably osmium, mobilization by hydrothermal fluids that permeated the intrusion shortly after crystallization. Initial osmium isotopic variability observed in chromitites and other rocks from the Stillwater Complex could result from interaction with these fluids. In this context, there is no compelling reason to call on assimilation of crust by mantle-derived magma to explain the osmium or neodymium isotopic variability. Although osmium isotopic systematics have been affected by hydrothermal processes, Re-Os results demonstrate that more than 95 percent of the osmium, and by inference other PGEs in the Stillwater Complex, derive from the mantle.

Paleobiological Implications of the Isotopic Signatures ( 13C, 15N) of Fossil Mammal Collagen in Scladina Cave (Sclayn, Belgium)

NASA Astrophysics Data System (ADS)

Bocherens, Hervé; Billiou, Daniel; Patou-Mathis, Marylène; Bonjean, Dominique; Otte, Marcel; Mariotti, André

1997-11-01

An isotopic investigation of upper Pleistocene mammal bones and teeth from Scladina cave (Sclayn, Belgium) demonstrated the very good quality of collagen preservation. A preliminary screening of the samples used the amount of nitrogen in whole bone and dentine in order to estimate the preserved amount of collagen before starting the extraction process. The isotopic abundances of fossil specimens from still-extant species are consistent with their trophic position. Moreover, the 15N isotopic abundance is higher in dentine than in bone in bears and hyenas, a phenomenon already observed in modern specimens. These results demonstrate that the isotopic compositions of samples from Scladina cave can be interpreted in ecological terms. Mammoths exhibit a high 15N isotopic abundance relative to other herbivores, as was the case in Siberian and Alaskan samples. These results suggest distinctive dietary adaptations in herbivores living in the mammoth steppe. Cave bears are clearly isotopically different from coeval brown bears, suggesting an ecological separation between species, with a pure vegetarian diet for cave bear and an omnivorous diet for brown bear.

Radioactive Cs capture in the early solar system

PubMed Central

Hidaka, Hiroshi; Yoneda, Shigekazu

2013-01-01

Barium isotopic compositions of primitive materials in the solar system are generally affected by s- and r-process nucleosynthetic components that hide the contribution of the isotopic excess of 135Ba formed by decay of radioactive 135Cs. However, the Ba isotopic composition of the chemical separates from chondrules in the Sayama CM2 chondrite shows an excess of 135Ba isotopic abundance up to (0.33 ± 0.06)%, which is independent of the isotopic components from s- and r-process nucleosyntheses. The isotopic excesses of 135Ba correlate with the elemental abundance of Ba relative to Cs, providing chemical and isotopic evidence for the existence of the presently extinct radionuclide 135Cs (t1/2 = 2.3 million years) in the early solar system. The estimated abundance of 135Cs/133Cs = (6.8 ± 1.9) × 10−4 is more than double that expected from the uniform production model of the short-lived radioisotopes, suggesting remobilization of Cs including 135Cs in the chondrules of the meteorite parent body. PMID:23435551

Longitudinal dispersion coefficient depending on superficial velocity of hydrogen isotopes flowing in column packed with zeolite pellets at 77.4 K

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kotoh, K.; Graduate School of Engineering, Kyushu University, Nishi-ku, Fukuoka; Kubo, K.

2015-03-15

Authors have been developing a cryogenic pressure swing adsorption system for hydrogen isotope separation. In the problem of its design and operation, it is necessary to predict the concentration profiles developing in packed beds of adsorbent pellets. The profiling is affected by the longitudinal dispersion of gas flowing in packed beds, in addition to the mass transfer resistance in porous media of adsorbent pellets. In this work, an equation is derived for estimating the packed-bed dispersion coefficient of hydrogen isotopes, by analyzing the breakthrough curves of trace D{sub 2} or HD replacing H{sub 2} adsorbed in synthetic zeolite particles packedmore » columns at the liquefied nitrogen temperature 77.4 K. Since specialized for hydrogen isotopes, this equation can be considered to estimate the dispersion coefficients more reliable for the cryogenic hydrogen isotope adsorption process, than the existing equations. (authors)« less

New technique for study on isotopic fractionation between sea water and foraminiferal growing processes

NASA Astrophysics Data System (ADS)

Cang, Shuxi; Shackleton, N. J.

1990-12-01

The stable isotopic δ18O and δ13C composition of foraminiferal shell calcite varies as a function of many factors including temperature and salinity. In order to understand and interpret the variations in the isotopic composition of foraminiferal shell calcite, research has been recently focused on the role of the “vital effects”. Our examination of the lamella structure of several recent planktonic foraminifera indicates that the secretion of sequential lamellae results in multiple lamillae on earlier chambers and a single lamella on the final chamber. We used a very simple procedure to separate the individual whole test of foraminifera into several chambers and measured the isotopic composition of each growth stage chamber. The results indicate that the stable isotopic composition (carbon and oxygen), particularly that of the last two chambers, of the foraminiferal test varies as a function of the individual growing process.

Isotopic Changes During Digestion: Protein

NASA Astrophysics Data System (ADS)

Tuross, N.

2013-12-01

Nutrient and hydrological inputs traverse a complicated route of pH, enzymatic and cellular processes in digestion in higher animals. The end products of digestion are the starting products for biosynthesis that are often used to interpret past life-ways. Using an artificial gut system, the isotopic changes (dD, d18O, d13C and d15N) of protein are documented. Three separate protein sources are subjected to the conditions, chemical and enzymatic, found in the stomach and upper small intestine with only a small shift in the oxygen isotopic composition of the proteins observed. Middle to lower small intestine parameters produced both greater isotopic effects and significantly lower molecular weight products. The role of the gastric enterocyte and the likely involvement of the internal milieu of this cell in the isotopic composition of amino acids that are transported to the liver are reported.

Secondary neutrons as the main source of neutron-rich fission products in the bombardment of a thick U target by 1 GeV protons

NASA Astrophysics Data System (ADS)

Barzakh, A. E.; Lhersonneau, G.; Batist, L. Kh.; Fedorov, D. V.; Ivanov, V. S.; Mezilev, K. A.; Molkanov, P. L.; Moroz, F. V.; Orlov, S. Yu.; Panteleev, V. N.; Volkov, Yu. M.; Alyakrinskiy, O.; Barbui, M.; Stroe, L.; Tecchio, L. B.

2011-05-01

The diffusion-effusion model has been used to analyse the release and yields of Fr and Cs isotopes from uranium carbide targets of very different thicknesses (6.3 and 148 g/cm2) bombarded by a 1 GeV proton beam. Release curves of several isotopes of the same element and production efficiency versus decay half-life are well fitted with the same set of parameters. Comparison of efficiencies for neutron-rich and neutron-deficient Cs isotopes enables separation of the contributions from the primary ( p + 238U) and secondary (n + 238U) reactions to the production of neutron-rich Cs isotopes. A rather simple calculation of the neutron contribution describes these data fairly well. The FLUKA code describes the primary and secondary-reaction contributions to the Cs isotopes production efficiencies for different targets quite well.

Radioisotope dilution analyses of geological samples using 236U and 229Th

USGS Publications Warehouse

Rosholt, J.N.

1984-01-01

The use of 236U and 229Th in alpha spectrometric measurements has some advantages over the use of other tracers and measurement techniques in isotope dilution analyses of most geological samples. The advantages are: (1) these isotopes do not occur in terrestrial rocks, (2) they have negligible decay losses because of their long half lives, (3) they cause minimal recoil contamination to surface-barrier detectors, (4) they allow for simultaneous determination of the concentration and isotopic composition of uranium and thorium in a variety of sample types, and (5) they allow for simple and constant corrections for spectral inferences, 0.5% of the 238U activity is subtracted for the contribution of 235U in the 236U peak and 1% of the 229Th activity is subtracted from the 230Th activity. Disadvantages in using 236U and 229Th are: (1) individual separates of uranium and thorium must be prepared as very thin sources for alpha spectrometry, (2) good resolution in the spectrometer system is required for thorium isotopic measurements where measurement times may extend to 300 h, and (3) separate calibrations of the 236U and 229Th spike solution with both uranium and thorium standards are required. The use of these tracers in applications of uranium-series disequilibrium studies has simplified the measurements required for the determination of the isotopic composition of uranium and thorium because of the minimal corrections needed for alpha spectral interferences. ?? 1984.

Spectroscopic Measurement of LEAD-204 Isotope Shift and LEAD-205 Nuclear Spin.

NASA Astrophysics Data System (ADS)

Schonberger, Peter

The isotope shift of ('204)Pb and the nuclear spin of 1.4 x 10('7)-y ('205)Pb was determined from a high -resolution optical measurement of the 6p('2) ('3)P(,o) -6p7s('3)P(,1)('o) 283.3-nm resonance line. The value of the shift, relative to ('208)Pb is -140.2(8) x 10('-3)cm(' -1), the negative sign indicating a shift to lower wave numbers. The precision is 3-4 times greater than that of previous measurements. The spin of ('205)Pb l = 5/2 was obtained from the measurement of the relative intensities of its three hyperfine components. This method of absorption spectroscopy determination of ground state nuclear spin is applicable to any stable or longlived isotope. High resolution optical absorption spectra were obtained with a 25.4cm diffraction grating in a 9.1m focal length Czerny-Turner spectrometer. A signal-averaging scanning technique was used to record the spectra. Increased precision in the isotope shift measurement was attained by using separated isotope samples of ('204)Pb and ('207)Pb. A controlled amount of the later was incorporated in the absorption cell to provide internal calibration by its 6p7s ('3)P(,1)('o) hfs separation. Absorption spectra were recorded for several optical thicknesses of the absorber. A single spin value of increased precision was derived from the entire set of combined data.

Biochemical and physiological bases for the use of carbon and nitrogen isotopes in environmental and ecological studies

NASA Astrophysics Data System (ADS)

Ohkouchi, Naohiko; Ogawa, Nanako O.; Chikaraishi, Yoshito; Tanaka, Hiroyuki; Wada, Eitaro

2015-12-01

We review the biochemical and physiological bases of the use of carbon and nitrogen isotopic compositions as an approach for environmental and ecological studies. Biochemical processes commonly observed in the biosphere, including the decarboxylation and deamination of amino acids, are the key factors in this isotopic approach. The principles drawn from the isotopic distributions disentangle the complex dynamics of the biosphere and allow the interactions between the geosphere and biosphere to be analyzed in detail. We also summarize two recently examined topics with new datasets: the isotopic compositions of individual biosynthetic products (chlorophylls and amino acids) and those of animal organs for further pursuing the basis of the methodology. As a tool for investigating complex systems, compound-specific isotopic analysis compensates the intrinsic disadvantages of bulk isotopic signatures. Chlorophylls provide information about the particular processes of various photoautotrophs, whereas amino acids provide a precise measure of the trophic positions of heterotrophs. The isotopic distributions of carbon and nitrogen in a single organism as well as in the whole biosphere are strongly regulated, so that their major components such as amino acids are coordinated appropriately rather than controlled separately.

Production of highly-enriched 134Ba for a reference material for isotope dilution mass spectrometry measurements

DOE PAGES

Horkley, J. J.; Carney, K. P.; Gantz, E. M.; ...

2015-03-17

Isotope dilution mass spectrometry (IDMS) is an analytical technique capable of providing accurate and precise quantitation of trace isotope abundance and assay providing measurement uncertainties below 1 %. To achieve these low uncertainties, the IDMS method ideally utilizes chemically pure “spike” solutions that consist of a single highly enriched isotope that is well-characterized relating to the abundance of companion isotopes and concentration in solution. To address a current demand for accurate 137Cs/137Ba ratio measurements for “age” determination of radioactive 137Cs sources, Idaho National Laboratory (INL) is producing enriched 134Ba isotopes that are tobe used for IDMS spikes to accurately determinemore » 137Ba accumulation from the decay of 137Cs. The final objective of this work it to provide a homogenous set of reference materials that the National Institute of Standards and Technology can certify as standard reference materials used for IDMS. The process that was developed at INL for the separation and isolation of Ba isotopes, chemical purification of the isotopes in solution, and the encapsulation of the materials will be described.« less

Advancing the Theory of Nuclear Reactions with Rare Isotopes: From the Laboratory to the Cosmos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elster, Charlotte

2015-06-01

The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct-reaction calculations, and, by using a new partial-fusion theory, to integrate descriptions of direct and compound-nucleus reactions. Ohio University concentrates its efforts on the first part of the mission. Since direct measurements are often not feasible, indirect methods, e.g. (d,p) reactions, should be used. Those (d,p) reactions may be viewed as three-body reactions and described with Faddeev techniques. Faddeev equations in momentum space have a long tradition of utilizing separable interactions in ordermore » to arrive at sets of coupled integral equations in one variable. While there exist several separable representations for the nucleon-nucleon interaction, the optical potential between a neutron (proton) and a nucleus is not readily available in separable form. For this reason we first embarked in introducing a separable representation for complex phenomenological optical potentials of Woods-Saxon type.« less

Estimation of Some Parameters from Morse-Morse-Spline-Van Der Waals Intermolecular Potential

NASA Astrophysics Data System (ADS)

Coroiu, I.

2007-04-01

Some parameters such as transport cross-sections and isotopic thermal diffusion factor have been calculated from an improved intermolecular potential, Morse-Morse-Spline-van der Waals (MMSV) potential proposed by R.A. Aziz et al. The treatment was completely classical and no corrections for quantum effects were made. The results would be employed for isotope separations of different spherical and quasi-spherical molecules.

VARIATIONS IN ISOTOPIC ABUNDANCES OF STRONTIUM, CALCIUM, AND ARGON AND RELATED TOPICS. Eleventh Annual Progress Report for 1963

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1963-12-01

Separate abstracts were prepared for twenty-eight of the thirty-three papers. The other papers deal with whole-rock Rb- Sr ages of Ontario norite and micropegmatite and the Southern Rhodesia Great Dyke, Sr isotopes in vein type mineral deposits, whole-rock Rb-- Sr studies of volcanics, and accuracy in Sr / sup 87//Sr/sup 86/ measurements. (D.C.W.)

A rapid method for estimation of Pu-isotopes in urine samples using high volume centrifuge.

PubMed

Kumar, Ranjeet; Rao, D D; Dubla, Rupali; Yadav, J R

2017-07-01

The conventional radio-analytical technique used for estimation of Pu-isotopes in urine samples involves anion exchange/TEVA column separation followed by alpha spectrometry. This sequence of analysis consumes nearly 3-4 days for completion. Many a times excreta analysis results are required urgently, particularly under repeat and incidental/emergency situations. Therefore, there is need to reduce the analysis time for the estimation of Pu-isotopes in bioassay samples. This paper gives the details of standardization of a rapid method for estimation of Pu-isotopes in urine samples using multi-purpose centrifuge, TEVA resin followed by alpha spectrometry. The rapid method involves oxidation of urine samples, co-precipitation of plutonium along with calcium phosphate followed by sample preparation using high volume centrifuge and separation of Pu using TEVA resin. Pu-fraction was electrodeposited and activity estimated using 236 Pu tracer recovery by alpha spectrometry. Ten routine urine samples of radiation workers were analyzed and consistent radiochemical tracer recovery was obtained in the range 47-88% with a mean and standard deviation of 64.4% and 11.3% respectively. With this newly standardized technique, the whole analytical procedure is completed within 9h (one working day hour). Copyright © 2017 Elsevier Ltd. All rights reserved.

Carbon isotopic analysis of atmospheric methane by isotope-ratio-monitoring gas chromatography-mass spectrometry

NASA Technical Reports Server (NTRS)

Merritt, Dawn A.; Hayes, J. M.; Des Marais, David J.

1995-01-01

Less than 15 min are required for the determination of delta C(sub PDB)-13 with a precision of 0.2 ppt(1 sigma, single measurement) in 5-mL samples of air containing CH4 at natural levels (1.7 ppm). An analytical system including a sample-introduction unit incorporating a preparative gas chromatograph (GC) column for separation of CH4 from N2, O2, and Ar is described. The 15-min procedure includes time for operation of that system, high-resolution chromatographic separation of the CH4, on-line combustion and purification of the products, and isotopic calibration. Analyses of standards demonstrate that systematic errors are absent and that there is no dependence of observed values of delta on sample size. For samples containing 100 ppm or more CH4, preconcentration is not required and the analysis time is less than 5 min. The system utilizes a commercially available, high-sensitivity isotope-ratio mass spectrometer. For optimal conditions of smaple handling and combustion, performance of the system is within a factor of 2 of the shot-noise limit. The potential exists therefore for analysis of samples as small as 15 pmol CH4 with a standard deviation of less than 1 ppt.

Application of Sr and O isotope relations to the petrogenesis of the alkaline rocks of the Red Hill complex, New Hampshire, USA

USGS Publications Warehouse

Foland, K.A.; Friedman, I.

1977-01-01

The Red Hill ring complex in central New Hampshire is composed of apparently cogenetic syenites, nepheline-sodalite syenite, and granite. The ages and petrogenetic relations among five of the six recognized units have been investigated by rubidiumstrontium and oxygen isotope analysis of whole rocks and separated minerals. Whole-rock samples from three syenite units are consistent with a single Rb-Sr isochron which gives an age of 198??3 m.y. and an initial (87Sr/86Sr)o ratio of 0.70330??0.00016 (??2 sigma; ??=1.42?? 10-11y-1). However, Sr isotope data for two other units, nepheline syenite and granite, are not consistent with this isochron but rather indicate higher initial ratios which range from 0.7033 to about 0.707. Whole-rock O isotope analyses give ??18O values which range from+6.2 to+9.3??? Sr and O isotope analyses on mineral separates indicate that observed whole-rock variations in (87Sr/86Sr)o are primary and are not due to any secondary process. The fact that the isotope systematics correlate with rock type, suggests that crustal interaction is likely to have played a significant role in the development of this over-and undersaturated association. Such process(es), while still not fully delineated, could be of fundamental importance to the genesis of associations of critically undersaturated and oversaturated intrusives. The data support the idea that interaction between magmas and crustal materials strongly influenced the compositional relations of similar complexes elsewhere including those of the White Mountain magma series. ?? 1977 Springer-Verlag.

Biometrics from the carbon isotope ratio analysis of amino acids in human hair.

PubMed

Jackson, Glen P; An, Yan; Konstantynova, Kateryna I; Rashaid, Ayat H B

2015-01-01

This study compares and contrasts the ability to classify individuals into different grouping factors through either bulk isotope ratio analysis or amino-acid-specific isotope ratio analysis of human hair. Using LC-IRMS, we measured the isotope ratios of 14 amino acids in hair proteins independently, and leucine/isoleucine as a co-eluting pair, to provide 15 variables for classification. Multivariate analysis confirmed that the essential amino acids and non-essential amino acids were mostly independent variables in the classification rules, thereby enabling the separation of dietary factors of isotope intake from intrinsic or phenotypic factors of isotope fractionation. Multivariate analysis revealed at least two potential sources of non-dietary factors influencing the carbon isotope ratio values of the amino acids in human hair: body mass index (BMI) and age. These results provide evidence that compound-specific isotope ratio analysis has the potential to go beyond region-of-origin or geospatial movements of individuals-obtainable through bulk isotope measurements-to the provision of physical and characteristic traits about the individuals, such as age and BMI. Further development and refinement, for example to genetic, metabolic, disease and hormonal factors could ultimately be of great assistance in forensic and clinical casework. Copyright © 2014 Forensic Science Society. Published by Elsevier Ireland Ltd. All rights reserved.

Isotopic decoupling during porous melt flow: A case-study in the Lherz peridotite

NASA Astrophysics Data System (ADS)

Le Roux, V.; Bodinier, J.-L.; Alard, O.; O'Reilly, S. Y.; Griffin, W. L.

2009-03-01

Most peridotite massifs and mantle xenoliths show a wide range of isotopic variations, often involving significant decoupling between Hf, Nd and Sr isotopes. These variations are generally ascribed either to mingling of individual components of contrasted isotopic compositions or to time integration of parent-element enrichment by percolating melts/fluids, superimposed onto previous depletion event(s). However, strong isotopic decoupling may also arise during porous flow as a result of daughter-elements fractionation during solid-liquid interaction. Although porous flow is recognized as an important process in mantle rocks, its effects on mantle isotopic variability have been barely investigated so far. The peridotites of the Lherz massif (French Pyrenees) display a frozen melt percolation front separating highly refractory harzburgites from refertilized lherzolites. Isotopic signatures observed at the melt percolation front show a strong decoupling of Hf from Nd and Sr isotopes that cannot be accounted for by simple mixing involving the harzburgite protolith and the percolating melt. Using one dimensional percolation-diffusion and percolation-reaction modeling, we show that these signatures represent transient isotopic compositions generated by porous flow. These signatures are governed by a few critical parameters such as daughter element concentrations in melt and peridotite, element diffusivity, and efficiency of isotopic homogenization rather than by the chromatographic effect of melt transport and the refertilization reaction. Subtle variations in these parameters may generate significant inter-isotopic decoupling and wide isotopic variations in mantle rocks.

Experiments on the Synthesis of Superheavy Elements with 48CA Beams at the Separator Vassilissa

NASA Astrophysics Data System (ADS)

Oganessian, Yu. Ts.; Yeremin, A. V.; Belozerov, A. V.; Chelnokov, M. L.; Chepigin, V. I.; Gorshkov, V. A.; Kabachenko, A. P.; Korotkov, S. P.; Malyshev, O. N.; Popeko, A. G.; Roháč, J.; Sagaidak, R. N.; Hofmann, S.; Münzenberg, G.; Veselsky, M.; Saro, S.; Iwasa, N.; Morita, K.; Giardina, G.

2001-04-01

The study of the decay properties and formation cross sections of the isotopes of elements 110, 112 and 114 were performed at the FLNR JINR with the use of the high intensity 48Ca beams and an electrostatic separator VASSILISSA. 232Th, 238U and 242Pu targets were used in the experiments. At the beam energies corresponding to the calculated cross section maxima of the 3n evaporation channels the isotopes 277110, 283112 and 287114 were produced and identified. The cross section limits were obtained at excitation energies of the compound nucleus corresponding to the maxima of the 4n evaporation channels for the reactions with 232Th and 238U targets.

Study of isomeric states in 198,200,202,206Pb and 206Hg populated in fragmentation reactions

NASA Astrophysics Data System (ADS)

Lalović, N.; Rudolph, D.; Podolyák, Zs; Sarmiento, L. G.; Simpson, E. C.; Alexander, T.; Cortés, M. L.; Gerl, J.; Golubev, P.; Ameil, F.; Arici, T.; Bauer, Ch; Bazzacco, D.; Bentley, M. A.; Boutachkov, P.; Bowry, M.; Fahlander, C.; Gadea, A.; Gellanki, J.; Givechev, A.; Goel, N.; Górska, M.; Gottardo, A.; Gregor, E.; Guastalla, G.; Habermann, T.; Hackstein, M.; Jungclaus, A.; Kojouharov, I.; Kumar, R.; Kurz, N.; Lettmann, M.; Lizarazo, C.; Louchart, C.; Merchán, E.; Michelagnoli, C.; Moeller, Th; Moschner, K.; Patel, Z.; Pietralla, N.; Pietri, S.; Ralet, D.; Reese, M.; Regan, P. H.; Reiter, P.; Schaffner, H.; Singh, P.; Stahl, C.; Stegmann, R.; Stezowski, O.; Taprogge, J.; Thöle, P.; Wendt, A.; Wieland, O.; Wilson, E.; Wood, R.; Wollersheim, H.-J.; Birkenbach, B.; Bruyneel, B.; Burrows, I.; Clément, E.; Désesquelles, P.; Domingo-Pardo, C.; Eberth, J.; González, V.; Hess, H.; Jolie, J.; Judson, D. S.; Menegazzo, R.; Mengoni, D.; Napoli, D. R.; Pullia, A.; Quintana, B.; Rainovski, G.; Salsac, M. D.; Sanchis, E.; Simpson, J.; Valiente Dóbon, J. J.; AGATA Collaboration

2018-03-01

Isomeric states in isotopes in the vicinity of doubly-magic 208Pb were populated following reactions of a relativistic 208Pb primary beam impinging on a 9Be fragmentation target. Secondary beams of 198,200,202,206Pb and 206Hg were isotopically separated and implanted in a passive stopper positioned in the focal plane of the GSI Fragment Separator. Delayed γ rays were detected with the Advanced Gamma Tracking Array (AGATA). Decay schemes were re-evaluated and interpreted with shell-model calculations. The momentum-dependent population of isomeric states in the two-nucleon hole nuclei 206Pb/206Hg was found to differ from the population of multi neutron-hole isomeric states in 198,200,202Pb.

Separated isotopes: Vital tools for science and medicine

NASA Astrophysics Data System (ADS)

Deliberations and conclusions of a workshop on stable isotopes and derived radioisotopes organized by the Subcommittee on Nuclear and Radiochemistry of the National Research Council's Committee on Chemical Sciences at the request of the Department of Energy (DOE) are summarized. The workshop was jointly supported by the National Institutes of Health and DOE's Office of Basic Energy Sciences. An overview with three recommendations resulting from the workshop is followed by reports of the four workshop panels. Background papers were prepared by individuals on the Steering Committee and made available to all participants prior to the Workshop. They are reproduced as Appendixes 3 to 8. Short reports on alternate separation techniques were presented at the Workshop and are reproduced in Appendixes 9 to 11.

Ecohydrologic Separation of Plant Life Forms Across A Soil Moisture Gradient in a Montane Wetland

NASA Astrophysics Data System (ADS)

Mercer, J.; Millar, D.; Williams, D. G.

2016-12-01

Sources of water used by plants can differ from those that flow to groundwater and streams. Such ecohydrologic separation forms the basis for the "two water worlds hypothesis" that challenges commonly held notions of how water moves through terrestrial ecosystems. Yet, recent observations in a humid, low energy wetland environment did not support the presence of ecohydrologic separation. These contrasting results, in the context of general physical principles, suggest that energy gradients along the soil-plant-atmosphere continuum may play a role in defining the magnitude of ecohydrologic separation. We quantified ecohydrologic separation in a montane wetland with pronounced hummocks and hollows located in southeastern Wyoming. The rooting zone in this wetland is fully saturated during the spring, but is prone to water table draw-downs (> 1 m) during the summer, likely producing significant water potential differences between plant and soil water pools. We predict that wetland vegetation will express some degree of ecohydrologic separation, but such expression will differ based on microtopgraphic position and the rooting strategy of different plant life form (i.e., trees, shrubs, graminoids). For example, shallowly rooted graminoids on raised hummocks may use water that is distinctly different from that located in wetter hollows, with water in hollows being more isotopically similar to water leaving the wetland via surface water flows. We collected xylem water from dominant plant life forms in hummocks and hollows, free water (via piezometers) and bulk soil water at depths of 20 and 60 cm, as well as surface water and groundwater. Stable isotope ratios of H and O were determined from samples by either laser spectroscopy or isotope ratio mass spectrometry. Our expected results suggest that most of the water being used by wetland plants will be similar to that leaving the wetland via surface flow. In the context of their being two water worlds in the surrounding forested uplands, we suggest that mountain wetlands may play a more important role in provisioning streamflow than previously thought.

You are not always what we think you eat. Selective assimilation across multiple whole-stream isotopic tracer studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dodds, W. K.; Collins, S. M.; Hamilton, S. K.

Analyses of 21 15N stable isotope tracer experiments, designed to examine food web dynamics in streams around the world, indicated that the isotopic composition of food resources assimilated by primary consumers (mostly invertebrates) poorly reflected the presumed food sources. Modeling indicated that consumers assimilated only 33–50% of the N available in sampled food sources such as decomposing leaves, epilithon, and fine particulate detritus over feeding periods of weeks or more. Thus, common methods of sampling food sources consumed by animals in streams do not sufficiently reflect the pool of N they assimilate. Lastly, Isotope tracer studies, combined with modeling andmore » food separation techniques, can improve estimation of N pools in food sources that are assimilated by consumers.« less

You are not always what we think you eat. Selective assimilation across multiple whole-stream isotopic tracer studies

DOE PAGES

Dodds, W. K.; Collins, S. M.; Hamilton, S. K.; ...

2014-10-01

Analyses of 21 15N stable isotope tracer experiments, designed to examine food web dynamics in streams around the world, indicated that the isotopic composition of food resources assimilated by primary consumers (mostly invertebrates) poorly reflected the presumed food sources. Modeling indicated that consumers assimilated only 33–50% of the N available in sampled food sources such as decomposing leaves, epilithon, and fine particulate detritus over feeding periods of weeks or more. Thus, common methods of sampling food sources consumed by animals in streams do not sufficiently reflect the pool of N they assimilate. Lastly, Isotope tracer studies, combined with modeling andmore » food separation techniques, can improve estimation of N pools in food sources that are assimilated by consumers.« less

Circulation Plasma Centrifuge with Product Flow

NASA Astrophysics Data System (ADS)

Borisevich, V. D.; Potanin, E. P.

2018-05-01

We have analyzed the isotope separation in a high-frequency plasma circulating centrifuge operating with a product flow. The rotation of a weakly ionized plasma is ensured by a rotating magnetic field, while the countercurrent flow (circulation) is produced by a traveling magnetic field. We have calculated the dependences of the enrichment factor and the separative power of the centrifuge on a product flow. The optimal characteristics of the separation unit have been determined.

Evaluating Snowmelt Runoff Processes Using Stable Isotopes in a Permafrost Hillslope

NASA Astrophysics Data System (ADS)

Carey, S. K.

2004-05-01

Conceptual understanding of runoff generation in permafrost regions have been derived primarily from hydrometric information, with isotope and hydrochemical data having only limited application in delineating sources and pathways of water. Furthermore, when stable isotope data are used to infer runoff processes, it often provides conflicting results from hydrometric measurements. In a small subarctic alpine catchment within the Wolf Creek Research Basin, Yukon, Canada, experiments were conducted during the melt period of 2002 and 2003 to trace the stable isotopic signature (d18O) of meltwater from a melting snowpack into permafrost soils and laterally to the stream to identify runoff processes and evaluate sources of error for traditional hydrograph separation studies in snowmelt-dominated permafrost basins. Isotopic variability in the snowpack was recorded at 0.1 m depth intervals during the melt period and compared with the meltwater isotopic signature at the snowpack base collected in lysimeters. Throughout the melt period in both years, there was an isotopic enrichment of meltwater as the season progressed. A downslope transect of wells and piezometers were used to evaluate the influence of infiltrating meltwater and thawing ground on the subsurface d18O signature. As melt began, meltwater infiltrated the frozen porous organic layer, leading to liquid water saturation in the unsaturated pore spaces. Water sampled during this initial melt stage show soil water d18O mirroring that of the meltwater signal. As the melt season progressed, frozen soil began to melt, mixing enriched pre-melt soil water with meltwater. This mixing increased the overall value of d18O obtained from the soil, which gradually increased as thaw progressed. At the end of snowmelt, soil water had a d18O value similar to values from the previous fall, suggesting that much of the initial snowmelt water had been flushed from the hillslope. Results from the hillslope scale are compared with two-component hydrograph separations and sources of error are discussed.

VAPOR PRESSURE ISOTOPE EFFECTS IN THE MEASUREMENT OF ENVIRONMENTAL TRITIUM SAMPLES.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhne, W.

2012-12-03

Standard procedures for the measurement of tritium in water samples often require distillation of an appropriate sample aliquot. This distillation process may result in a fractionation of tritiated water and regular light water due to the vapor pressure isotope effect, introducing either a bias or an additional contribution to the total tritium measurement uncertainty. The magnitude of the vapor pressure isotope effect is characterized as functions of the amount of water distilled from the sample aliquot and the heat settings for the distillation process. The tritium concentration in the distillate is higher than the tritium concentration in the sample earlymore » in the distillation process, it then sharply decreases due to the vapor pressure isotope effect and becomes lower than the tritium concentration in the sample, until the high tritium concentration retained in the boiling flask is evaporated at the end of the process. At that time, the tritium concentration in the distillate again overestimates the sample tritium concentration. The vapor pressure isotope effect is more pronounced the slower the evaporation and distillation process is conducted; a lower heat setting during the evaporation of the sample results in a larger bias in the tritium measurement. The experimental setup used and the fact that the current study allowed for an investigation of the relative change in vapor pressure isotope effect in the course of the distillation process distinguish it from and extend previously published measurements. The separation factor as a quantitative measure of the vapor pressure isotope effect is found to assume values of 1.034 {+-} 0.033, 1.052 {+-} 0.025, and 1.066 {+-} 0.037, depending on the vigor of the boiling process during distillation of the sample. A lower heat setting in the experimental setup, and therefore a less vigorous boiling process, results in a larger value for the separation factor. For a tritium measurement in water samples, this implies that the tritium concentration could be underestimated by 3 - 6%.« less

Copper isotope fractionation during surface adsorption and intracellular incorporation by bacteria

PubMed Central

Navarrete, Jesica U.; Borrok, David M.; Viveros, Marian; Ellzey, Joanne T.

2011-01-01

Copper isotopes may prove to be a useful tool for investigating bacteria–metal interactions recorded in natural waters, soils, and rocks. However, experimental data which attempt to constrain Cu isotope fractionation in biologic systems are limited and unclear. In this study, we utilized Cu isotopes (δ65Cu) to investigate Cu–bacteria interactions, including surface adsorption and intracellular incorporation. Experiments were conducted with individual representative species of Gram-positive (Bacillus subtilis) and Gram-negative (Escherichia coli) bacteria, as well as with wild-type consortia of microorganisms from several natural environments. Ph-dependent adsorption experiments were conducted with live and dead cells over the pH range 2.5–6. Surface adsorption experiments of Cu onto live bacterial cells resulted in apparent separation factors (Δ65Cusolution–solid = δ65Cusolution – δ65Cusolid) ranging from +0.3‰ to +1.4‰ for B. subtilis and +0.2‰ to +2.6‰ for E. coli. However, because heat-killed bacterial cells did not exhibit this behavior, the preference of the lighter Cu isotope by the cells is probably not related to reversible surface adsorption, but instead is a metabolically-driven phenomenon. Adsorption experiments with heat-killed cells yielded apparent separation factors ranging from +0.3‰ to –0.69‰ which likely reflects fractionation from complexation with organic acid surface functional group sites. For intracellular incorporation experiments the lab strains and natural consortia preferentially incorporated the lighter Cu isotope with an apparent Δ65Cusolution–solid ranging from ~+1.0‰ to +4.4‰. Our results indicate that live bacterial cells preferentially sequester the lighter Cu isotope regardless of the experimental conditions. The fractionation mechanisms involved are likely related to active cellular transport and regulation, including the reduction of Cu(II) to Cu(I). Because similar intracellular Cu machinery is shared by fungi, plants, and higher organisms, the influence of biological processes on the δ65Cu of natural waters and soils is probably considerable. PMID:21785492

10 CFR 110.40 - Commission review.

Code of Federal Regulations, 2010 CFR

2010-01-01

... Canada. (5) An export involving assistance to end uses related to isotope separation, chemical reprocessing, heavy water production, advanced reactors, or the fabrication of nuclear fuel containing...

Resonance ionization laser ion sources for on-line isotope separators (invited).

PubMed

Marsh, B A

2014-02-01

A Resonance Ionization Laser Ion Source (RILIS) is today considered an essential component of the majority of Isotope Separator On Line (ISOL) facilities; there are seven laser ion sources currently operational at ISOL facilities worldwide and several more are under development. The ionization mechanism is a highly element selective multi-step resonance photo-absorption process that requires a specifically tailored laser configuration for each chemical element. For some isotopes, isomer selective ionization may even be achieved by exploiting the differences in hyperfine structures of an atomic transition for different nuclear spin states. For many radioactive ion beam experiments, laser resonance ionization is the only means of achieving an acceptable level of beam purity without compromising isotope yield. Furthermore, by performing element selection at the location of the ion source, the propagation of unwanted radioactivity downstream of the target assembly is reduced. Whilst advances in laser technology have improved the performance and reliability of laser ion sources and broadened the range of suitable commercially available laser systems, many recent developments have focused rather on the laser/atom interaction region in the quest for increased selectivity and/or improved spectral resolution. Much of the progress in this area has been achieved by decoupling the laser ionization from competing ionization processes through the use of a laser/atom interaction region that is physically separated from the target chamber. A new application of gas catcher laser ion source technology promises to expand the capabilities of projectile fragmentation facilities through the conversion of otherwise discarded reaction fragments into high-purity low-energy ion beams. A summary of recent RILIS developments and the current status of laser ion sources worldwide is presented.

Insights into plant water uptake from xylem-water isotope measurements in two tropical catchments with contrasting moisture conditions

USGS Publications Warehouse

Evaristo, Jaivime; McDonnell, Jeffrey J.; Scholl, Martha A.; Bruijnzeel, L. Adrian; Chun, Kwok P.

2016-01-01

Water transpired by trees has long been assumed to be sourced from the same subsurface water stocks that contribute to groundwater recharge and streamflow. However, recent investigations using dual water stable isotopes have shown an apparent ecohydrological separation between tree-transpired water and stream water. Here we present evidence for such ecohydrological separation in two tropical environments in Puerto Rico where precipitation seasonality is relatively low and where precipitation is positively correlated with primary productivity. We determined the stable isotope signature of xylem water of 30 mahogany (Swietenia spp.) trees sampled during two periods with contrasting moisture status. Our results suggest that the separation between transpiration water and groundwater recharge/streamflow water might be related less to the temporal phasing of hydrologic inputs and primary productivity, and more to the fundamental processes that drive evaporative isotopic enrichment of residual soil water within the soil matrix. The lack of an evaporative signature of both groundwater and streams in the study area suggests that these water balance components have a water source that is transported quickly to deeper subsurface storage compared to waters that trees use. A Bayesian mixing model used to partition source water proportions of xylem water showed that groundwater contribution was greater for valley-bottom, riparian trees than for ridge-top trees. Groundwater contribution was also greater at the xeric site than at the mesic–hydric site. These model results (1) underline the utility of a simple linear mixing model, implemented in a Bayesian inference framework, in quantifying source water contributions at sites with contrasting physiographic characteristics, and (2) highlight the informed judgement that should be made in interpreting mixing model results, of import particularly in surveying groundwater use patterns by vegetation from regional to global scales. 

Preliminary results from a microvolume, dynamically heated analytical column for preconcentration and separation of simple gases prior to stable isotopic analysis

NASA Astrophysics Data System (ADS)

Panetta, Robert James; Seed, Mike

2016-04-01

Stable isotope applications that call for preconcentration (i.e., greenhouse gas measurements, small carbonate samples, etc.) universally call for cryogenic fluids such as liquid nitrogen, dry ice slurries, or expensive external recirculation chillers. This adds significant complexity, first and foremost in the requirements to store and handle such dangerous materials. A second layer of complexity is the instrument itself - with mechanisms to physically move either coolant around the trap, or move a trap in or out of the coolant. Not to mention design requirements for hardware that can safely isolate the fluid from other sensitive areas. In an effort to simplify the isotopic analysis of gases requiring preconcentration, we have developed a new separation technology, UltiTrapTM (patent pending), which leverage's the proprietary Advanced Purge & Trap (APT) Technology employed in elemental analysers from Elementar Analysensysteme GmbH products. UltiTrapTM has been specially developed as a micro volume, dynamically heated GC separation column. The introduction of solid-state cooling technology enables sub-zero temperatures without cryogenics or refrigerants, eliminates all moving parts, and increases analytical longevity due to no boiling losses of coolant . This new technology makes it possible for the system to be deployed as both a focussing device and as a gas separation device. Initial data on synthetic gas mixtures (CO2/CH4/N2O in air), and real-world applications including long-term room air and a comparison between carbonated waters of different origins show excellent agreement with previous technologies.

Identification of New Neutron-Rich Isotopes in the Rare-Earth Region Produced by 345 MeV/nucleon 238U

NASA Astrophysics Data System (ADS)

Fukuda, Naoki; Kubo, Toshiyuki; Kameda, Daisuke; Inabe, Naohito; Suzuki, Hiroshi; Shimizu, Yohei; Takeda, Hiroyuki; Kusaka, Kensuke; Yanagisawa, Yoshiyuki; Ohtake, Masao; Tanaka, Kanenobu; Yoshida, Koichi; Sato, Hiromi; Baba, Hidetada; Kurokawa, Meiko; Ohnishi, Tetsuya; Iwasa, Naohito; Chiba, Ayuko; Yamada, Taku; Ideguchi, Eiji; Go, Shintaro; Yokoyama, Rin; Fujii, Toshihiko; Nishibata, Hiroki; Ieki, Kazuo; Murai, Daichi; Momota, Sadao; Nishimura, Daiki; Sato, Yoshiteru; Hwang, Jongwon; Kim, Sunji; Tarasov, Oleg B.; Morrissey, David J.; Simpson, Gary

2018-01-01

A search for new isotopes in the neutron-rich rare-earth region has been carried out using a 345 MeV/nucleon 238U beam at the RIKEN Nishina Center RI Beam Factory. Fragments produced were analyzed and identified using the BigRIPS in-flight separator. We observed a total of 29 new neutron-rich isotopes: 153Ba, 154,155,156La, 156,157,158Ce, 156,157,158,159,160,161Pr, 162,163Nd, 164,165Pm, 166,167Sm, 169Eu, 171Gd, 173,174Tb, 175,176Dy, 177,178Ho, and 179,180Er.

Lead isotope systematics of some igneous rocks from the Egyptian Shield

NASA Technical Reports Server (NTRS)

Gillespie, J. G.; Dixon, T. H.

1983-01-01

Lead isotope data on whole-rock samples and two feldspar separates for a variety of Pan-African (late Precambrian) igneous rocks for the Egyptian Shield are presented. It is pointed out that the eastern desert of Egypt is a Late Precambrian shield characterized by the widespread occurrence of granitic plutons. The lead isotope ratios may be used to delineate boundaries between Late Precambrian oceanic and continental environments in northeastern Africa. The samples belong to three groups. These groups are related to a younger plutonic sequence of granites and adamellites, a plutonic group consisting of older tonalites to granodiorites, and the Dokhan volcanic suite.

Identification of neutron deficient niobium, molybdenum and technetium isotopes

NASA Astrophysics Data System (ADS)

Gross, C. J.

We report on the in-beam identification of fourteen new isotopes in the A=80-90 region. Heavy-ion reactions with a recoil separator or charged particle and neutron detectors provided identification of γ-rays from these new niobium, molybdenum, and technetium isotopes. The procedures used are described and energy level systematics are discussed. The energy levels appear to be organized into rotational bands in nuclei with N≤44 while those with N ≥ 46 have more single-particle-like transitions. Lifetime measurements in 87Mo and 87Nb indicate that g {9}/{2} particle alignment strongly influences the collectivity of these nuclei.

Systematization of cross sections for the production of residual nuclei on separated tin isotopes in reactions induced by various-energy protons

DOE Office of Scientific and Technical Information (OSTI.GOV)

Balabekyan, A. R., E-mail: balabekyan@ysu.am; Danagulyan, A. S.; Drnoyan, J. R.

2011-05-15

Cross sections for the production of residual nuclei on the isotopes {sup 112,118,120,124}Sn irradiated with 0.66-, 1.0-, 3.65-, and 8.1-GeV proton beams were investigated. A ten-parameter semiempirical formula was used to systematize the cross sections in question. A comparative analysis of parameter values obtained at different proton energies was performed.

Analysis of hydrogen isotope mixtures

DOEpatents

Villa-Aleman, Eliel

1994-01-01

An apparatus and method for determining the concentrations of hydrogen isotopes in a sample. Hydrogen in the sample is separated from other elements using a filter selectively permeable to hydrogen. Then the hydrogen is condensed onto a cold finger or cryopump. The cold finger is rotated as pulsed laser energy vaporizes a portion of the condensed hydrogen, forming a packet of molecular hydrogen. The desorbed hydrogen is ionized and admitted into a mass spectrometer for analysis.

Illuminating hydrological processes at the soil-vegetation-atmosphere interface with water stable isotopes

NASA Astrophysics Data System (ADS)

Sprenger, Matthias; Leistert, Hannes; Gimbel, Katharina; Weiler, Markus

2016-09-01

Water stable isotopes (18O and 2H) are widely used as ideal tracers to track water through the soil and to separate evaporation from transpiration. Due to the technical developments in the last two decades, soil water stable isotope data have become easier to collect. Thus, the application of isotope methods in soils is growing rapidly. Studies that make use of soil water stable isotopes often have a multidisciplinary character since an interplay of processes that take place in the vadose zone has to be considered. In this review, we provide an overview of the hydrological processes that alter the soil water stable isotopic composition and present studies utilizing pore water stable isotopes. The processes that are discussed include the water input as precipitation or throughfall, the output as evaporation, transpiration, or recharge, and specific flow and transport processes. Based on the review and supported by additional data and modeling results, we pose a different view on the recently proposed two water world hypothesis. As an alternative to two distinct pools of soil water, where one pool is enriched in heavy isotopes and used by the vegetation and the other pool does not undergo isotopic fractionation and becomes recharge, the water gets successively mixed with newly introduced rainwater during the percolation process. This way, water initially isotopically enriched in the topsoil loses the fractionation signal with increasing infiltration depth, leading to unfractionated isotopic signals in the groundwater.

Improved Multiple-Species Cyclotron Ion Source

NASA Technical Reports Server (NTRS)

Soli, George A.; Nichols, Donald K.

1990-01-01

Use of pure isotope 86Kr instead of natural krypton in multiple-species ion source enables source to produce krypton ions separated from argon ions by tuning cylcotron with which source used. Addition of capability to produce and separate krypton ions at kinetic energies of 150 to 400 MeV necessary for simulation of worst-case ions occurring in outer space.

Isotopic composition of reduced and oxidized sulfur in the Canary Islands: implications for the mantle S cycle

NASA Astrophysics Data System (ADS)

Beaudry, P.; Longpre, M. A.; Wing, B. A.; Bui, T. H.; Stix, J.

2017-12-01

The Earth's mantle contains distinct sulfur reservoirs, which can be probed by sulfur isotope analyses of volcanic rocks and gases. We analyzed the isotopic composition of reduced and oxidized sulfur in a diverse range of volcanically derived materials spanning historical volcanism in the Canary Islands. Our sample set consists of subaerial volcanic tephras from three different islands, mantle and sedimentary xenoliths, as well as lava balloon samples from the 2011-2012 submarine El Hierro eruption and associated crystal separates. This large sample set allows us to differentiate between the various processes responsible for sulfur isotope heterogeneity in the Canary archipelago. Our results define an array in triple S isotope space between the compositions of the MORB and seawater sulfate reservoirs. Specifically, the sulfide values are remarkably homogeneous around d34S = -1 ‰ and D33S = -0.01 ‰, while sulfate values peak at d34S = +4 ‰ and D33S = +0.01 ‰. Lava balloons from the El Hierro eruption have highly enriched sulfate d34S values up to +19.3 ‰, reflecting direct interaction between seawater sulfate and the erupting magma. Several sulfate data points from the island of Lanzarote also trend towards more positive d34S up to +13.8 ‰, suggesting interaction with seawater sulfate-enriched lithologies or infiltration of seawater within the magmatic system. On the other hand, the modal values and relative abundances of S2- and S6+ in crystal separates suggest that the Canary Island mantle source has a d34S around +3 ‰, similar to the S-isotopic composition of a peridotite xenolith from Lanzarote. We infer that the S2- and S6+ modes reflect isotopic equilibrium between those species in the magmatic source, which requires 80 % of the sulfide to become oxidized after melting, consistent with measured S speciation. This 34S enrichment of the source could be due to the recycling of hydrothermally-altered oceanic crust, which has been previously suggested for the Canary Island hotspot on the basis of radiogenic isotope characteristics.

Development of procedure for measurement of Pb isotope ratios in seawater by application of seaFAST sample pre-treatment system and Sector Field Inductively Coupled Plasma Mass Spectrometry

NASA Astrophysics Data System (ADS)

Vassileva, Emilia; Wysocka, Irena

2016-12-01

Anthropogenic Pb in the oceans, derived from high-temperature industrial processes, fuel combustion and incineration can have an isotopic signature distinct from naturally occurring Pb, supplied by rock weathering. To identify the different pollution sources accurately and to quantify their relative contributions, Pb isotope ratios are widely used. Due to the high salt content (approximately 3.5% of total dissolved solids) and very low levels of Pb (typically from 1 to 100 ng L- 1) in seawater the determination of Pb isotope ratios requires preliminary matrix separation and analyte preconcentration. An analytical protocol for the measurements of Pb isotope ratios in seawater combining seaFAST sample pre-treatment system and Sector Field Inductively Coupled Plasma Mass Spectrometry (SF ICP-MS) was developed. The application of seaFAST system was advantageous, because of its completely closed working cycle and small volumes of chemicals introduced in pre-treatment step, resulting in very low detection limits and procedural blanks. The preconcentration/matrix separation step was also of crucial importance for minimizing the isobaric and matrix interferences, coming from the seawater. In order to differentiate between anthropogenic and natural Pb sources, particular attention was paid to the determination of 204Pb isotope because of its implication in some geological interpretations. The validation of the analytical procedure was effectuated according to the recommendations of the ISO/IEC 17025 standard. The method was validated by processing the common Pb isotope reference material NIST SRM 981. All major sources of uncertainty were identified and propagated together following the ISO/GUM guidelines. The estimation of the total uncertainty associated to each measurement result was fundamental tool for sorting the main sources of possible biases. The developed analytical procedure was applied to the coastal and open seawater samples, collected in different regions of the world and revealed that the procedure is applicable for the measurement of Pb isotope ratios in seawater with combined uncertainty adequate to discuss the origin of Pb pollution in the ocean.

Changes in erosion and ocean circulation recorded in the Hf isotopic compositions of North Atlantic and Indian Ocean ferromanganese crusts

USGS Publications Warehouse

Piotrowski, Alexander M.; Lee, Der-Chuen; Christensen, John N.; Burton, Kevin W.; Halliday, Alex N.; Hein, James R.; Günther, Detlef

2000-01-01

High-resolution Hf isotopic records are presented for hydrogenetic Fe–Mn crusts from the North Atlantic and Indian Oceans. BM1969 from the western North Atlantic has previously been shown to record systematically decreasing Nd isotopic compositions from about 60 to ∼4 Ma, at which time both show a rapid decrease to unradiogenic Nd composition, thought to be related to the increasing influence of NADW or glaciation in the northern hemisphere. During the Oligocene, North Atlantic Hf became progressively less radiogenic until in the mid-Miocene (∼15 Ma) it reached +1. It then shifted gradually back to an ϵHf value of +3 at 4 Ma, since when it has decreased rapidly to about −1 at the present day. The observed shifts in the Hf isotopic composition were probably caused by variation in intensity of erosion as glaciation progressed in the northern hemisphere. Ferromanganese crusts SS663 and 109D are from about 5500 m depth in the Indian Ocean and are now separated by ∼2300 km across the Mid-Indian Ridge. They display similar trends in Hf isotopic composition from 20 to 5 Ma, with the more northern crust having a composition that is consistently more radiogenic (by ∼2 ϵHf units). Paradoxically, during the last 20 Ma the Hf isotopic compositions of the two crusts have converged despite increased separation and subsidence relative to the ridge. A correlatable negative excursion at ∼5 Ma in the two records may reflect a short-term increase in erosion caused by the activation of the Himalayan main central thrust. Changes to unradiogenic Hf in the central Indian Ocean after 5 Ma may alternatively have been caused by the expanding influence of NADW into the Mid-Indian Basin via circum-Antarctic deep water or a reduction of Pacific flow through the Indonesian gateway. In either case, these results illustrate the utility of the Hf isotope system as a tracer of paleoceanographic changes, capable of responding to subtle changes in erosional regime not readily resolved using other isotope systems.

Soil, the orphan hydrological compartment: evidence from O and H stable isotopes?

NASA Astrophysics Data System (ADS)

Hissler, Christophe; Legout, Arnaud; Barnich, François; Pfister, Laurent

2015-04-01

O and H stable isotopes have been successfully used for decades for studying the exchange of waters between the hydrosphere, the pedosphere and the biosphere. They greatly contribute to improve our understanding of soil-water-plant interactions. In particular, the recent hydrological concept of "two water worlds" (separation of meteoric water that infiltrates the soil as (i) mobile water, which can reach the groundwater and can enter the stream, and as (ii) tightly bound water, which is trapped in the soil microporosity and used by plants) calls for a substantial revision of our perceptual models of runoff generation. Nevertheless, there is a need for testing the applicability of this concept over a large range of ecosystemic contexts (i.e.soil and vegetation types). To date, many investigations have focused on the relationship between the various processes triggering isotope fractionation within soils. So far, the dominating perception is that the isotope profile of water observed in soils is solely due to evaporative fractionation and its shape is dependent on climate and soil parameters. However, as of today the influence of biogeochemical processes on the spatio-temporal variability of δ18O and δD of the soil solutions has been rarely quantified. O and H exchanges between soil water and other soil compartments (living organisms, minerals, exchange capacity, organic matter) remain poorly known and require deeper investigations. Eventually, we need to better understand the distribution of O and H isotopes throughout the soil matrix. In order to address these issues, we have designed and carried out two complementary isotope experiments that use one liter soil columns of a 2mm-sieved and air-dried soil. Our objectives were (1) to observe the temporal evolution of the water O and H isotopic composition starting from the field capacity to the complete drying of the soil and (2) to determine the impact of soil biogeochemical properties on the isotopic composition of different water types in soil (weakly-, moderately- and tightly-bound). Our results show that mobile and tightly bound water may have different hydrogen isotopic signatures and that their respective isotopic signatures may vary between horizons and soil types. However, it is not yet possible to quantify the contribution of different bio-physico-chemical processes to the oxygen and hydrogen isotopic composition of the soil water because the techniques at hand for water separation are not yet reliable enough. Prior to this type of quantifications, we need to focus in a next step at the improvement of water extraction methods.

Rapid fusion method for the determination of refractory thorium and uranium isotopes in soil samples

DOE PAGES

Maxwell, Sherrod L.; Hutchison, Jay B.; McAlister, Daniel R.

2015-02-14

Recently, approximately 80% of participating laboratories failed to accurately determine uranium isotopes in soil samples in the U.S Department of Energy Mixed Analyte Performance Evaluation Program (MAPEP) Session 30, due to incomplete dissolution of refractory particles in the samples. Failing laboratories employed acid dissolution methods, including hydrofluoric acid, to recover uranium from the soil matrix. The failures illustrate the importance of rugged soil dissolution methods for the accurate measurement of analytes in the sample matrix. A new rapid fusion method has been developed by the Savannah River National Laboratory (SRNL) to prepare 1-2 g soil sample aliquots very quickly, withmore » total dissolution of refractory particles. Soil samples are fused with sodium hydroxide at 600 ºC in zirconium crucibles to enable complete dissolution of the sample. Uranium and thorium are separated on stacked TEVA and TRU extraction chromatographic resin cartridges, prior to isotopic measurements by alpha spectrometry on cerium fluoride microprecipitation sources. Plutonium can also be separated and measured using this method. Batches of 12 samples can be prepared for measurement in <5 hours.« less

Modeling the Removal of Xenon from Lithium Hydrate with Aspen HYSYS

NASA Astrophysics Data System (ADS)

Efthimion, Phillip; Gentile, Charles

2011-10-01

The Laser Inertial Fusion Engine (LIFE) project mission is to provide a long-term, carbon-free source of sustainable energy, in the form of electricity. A conceptual xenon removal system has been modeled with the aid of Aspen HYSYS, a chemical process simulator. Aspen HYSYS provides excellent capability to model chemical flow processes, which generates outputs which includes specific variables such as temperature, pressure, and molar flow. The system is designed to strip out hydrogen isotopes deuterium and tritium. The base design bubbles plasma exhaust laden with x filled with liquid helium. The system separates the xenon from the hydrogen, deuterium, and tritium with a lithium hydrate and a lithium bubbler. After the removal of the hydrogen and its isotopes, the xenon is then purified by way of the process of cryogenic distillation. The pure hydrogen, deuterium, and tritium are then sent to the isotope separation system (ISS). The removal of xenon is an integral part of the laser inertial fusion engine and Aspen HYSYS is an excellent tool to calculate how to create pure xenon.

A Summary of Actinide Enrichment Technologies and Capability Gaps

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patton, Bradley D.; Robinson, Sharon M.

2017-01-01

The evaluation performed in this study indicates that a new program is needed to efficiently provide a national actinide radioisotope enrichment capability to produce milligram-to-gram quantities of unique materials for user communities. This program should leverage past actinide enrichment, the recent advances in stable isotope enrichment, and assessments of the future requirements to cost effectively develop this capability while establishing an experience base for a new generation of researchers in this vital area. Preliminary evaluations indicate that an electromagnetic isotope separation (EMIS) device would have the capability to meet the future needs of the user community for enriched actinides. Themore » EMIS technology could be potentially coupled with other enrichment technologies, such as irradiation, as pre-enrichment and/or post-enrichment systems to increase the throughput, reduce losses of material, and/or reduce operational costs of the base EMIS system. Past actinide enrichment experience and advances in the EMIS technology applied in stable isotope separations should be leveraged with this new evaluation information to assist in the establishment of a domestic actinide radioisotope enrichment capability.« less

Fission fragment yields from heavy-ion-induced reactions measured with a fragment separator

NASA Astrophysics Data System (ADS)

Tarasov, O. B.; Delaune, O.; Farget, F.; Morrissey, D. J.; Amthor, A. M.; Bastin, B.; Bazin, D.; Blank, B.; Cacéres, L.; Chbihi, A.; Fernández-Dominguez, B.; Grévy, S.; Kamalou, O.; Lukyanov, S. M.; Mittig, W.; Pereira, J.; Perrot, L.; Saint-Laurent, M.-G.; Savajols, H.; Sherrill, B. M.; Stodel, C.; Thomas, J. C.; Villari, A. C.

2018-04-01

The systematic study of fission fragment yields under different initial conditions has provided valuable experimental data for benchmarking models of fission product yields. Nuclear reactions using inverse kinematics coupled to the use of a high-resolution spectrometer with good fragment identification are shown here to be a powerful tool to measure the inclusive isotopic yields of fission fragments. In-flight fusion-fission was used in this work to produce secondary beams of neutron-rich isotopes in the collisions of a 238U beam at 24 MeV/u with 9Be and 12C targets at GANIL using the LISE3 fragment separator. Unique identification of the A, Z, and atomic charge state, q, of fission products was attained with the Δ E- TKE-B ρ- ToF measurement technique. Mass, and atomic number distributions are reported for the two reactions. The results show the importance of different reaction mechanisms in the two cases. The optimal target material for higher yields of neutron-rich high- Z isotopes produced in fusion-fission reactions as a function of projectile energy is discussed.

Hyperfine structure and isotope shift of /sup 208/Bi in the 3067-A resonance line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamontagne, J.J.

1982-01-01

The hyperfine structure of /sup 208/Bi (I = 5) was measured using the 3067 A spectral line from the 6p/sup 2/7s (/sup 4/P/sub 1/2/) - 6p/sup 3/ (/sup 4/S/sub 3/2/) transition. After production of the isotope at the Princeton University Cyclotron, chemical separation, and mass separation, some 10/sup 12/ atoms were used to produce an absorption spectrum. The monochromator, Czerny-Turner design), had a 9.1 m focal length with a 25 cm diffraction grating used in autocollimation near 63/sup 0/. The spectrum was recorded on photographic plates. Measurements were made of the position of the components. From these the value /supmore » 208/A (/sup 4/P/sub 1/2) = 166 (1.5) mK was obtained. Neglecting hyperfine anomalies this gives /sup 208/A (/sup 4/S/sub 3/2/) = 15.07 (.1). The isotope shift /sup 208/Bi-/sup 208/Bi was measured to be 50.58 (7.5) mK.« less

Mass measurements of neutron-deficient Y, Zr, and Nb isotopes and their impact on rp and νp nucleosynthesis processes

NASA Astrophysics Data System (ADS)

Xing, Y. M.; Li, K. A.; Zhang, Y. H.; Zhou, X. H.; Wang, M.; Litvinov, Yu. A.; Blaum, K.; Wanajo, S.; Kubono, S.; Martínez-Pinedo, G.; Sieverding, A.; Chen, R. J.; Shuai, P.; Fu, C. Y.; Yan, X. L.; Huang, W. J.; Xu, X.; Tang, X. D.; Xu, H. S.; Bao, T.; Chen, X. C.; Gao, B. S.; He, J. J.; Lam, Y. H.; Li, H. F.; Liu, J. H.; Ma, X. W.; Mao, R. S.; Si, M.; Sun, M. Z.; Tu, X. L.; Wang, Q.; Yang, J. C.; Yuan, Y. J.; Zeng, Q.; Zhang, P.; Zhou, X.; Zhan, W. L.; Litvinov, S.; Audi, G.; Uesaka, T.; Yamaguchi, Y.; Yamaguchi, T.; Ozawa, A.; Fröhlich, C.; Rauscher, T.; Thielemann, F.-K.; Sun, B. H.; Sun, Y.; Dai, A. C.; Xu, F. R.

2018-06-01

Using isochronous mass spectrometry at the experimental storage ring CSRe in Lanzhou, the masses of 82Zr and 84Nb were measured for the first time with an uncertainty of ∼10 keV, and the masses of 79Y, 81Zr, and 83Nb were re-determined with a higher precision. The latter are significantly less bound than their literature values. Our new and accurate masses remove the irregularities of the mass surface in this region of the nuclear chart. Our results do not support the predicted island of pronounced low α separation energies for neutron-deficient Mo and Tc isotopes, making the formation of Zr-Nb cycle in the rp-process unlikely. The new proton separation energy of 83Nb was determined to be 490(400) keV smaller than that in the Atomic Mass Evaluation 2012. This partly removes the overproduction of the p-nucleus 84Sr relative to the neutron-deficient molybdenum isotopes in the previous νp-process simulations.

Noble gases in Mars atmosphere: new precise analysis with Paloma

NASA Astrophysics Data System (ADS)

Sarda, Ph.; Paloma Team

2003-04-01

The Viking mission embarked a mass spectrometer designed by Alfred O. Nier that yielded the first determination of the elemental and isotopic composition of noble gases in Mars atmosphere. For example, the 40Ar/36Ar ratio in martian air is roughly 10 fold that in terrestrial air. This extraordinary accomplishment, however, has furnished only partial results with large analytical uncertainties. For example, we do not know the isotopic composition of helium, and only very poorly that of Ne, Kr and Xe. In planetary science, it is fundamental to have a good knowledge of the atmosphere because this serves as a reference for all further studies of volatiles. In addition, part of our present knowledge of Mars atmosphere is based on the SNC meteorites, and again points to important differences between the atmospheres of Earth and Mars. For example the 129Xe/132Xe ratio of martian atmosphere would be twice that of terrestrial air and the 36Ar/38Ar ratio strongly different from the terrestrial or solar value. There is a need for confirming that the atmospheric components found in SNC meteorites actually represents the atmosphere of Mars, or to determine how different they are. Paloma is an instrument designed to generate elemental and isotopic data for He, Ne, Ar, Kr and Xe (and other gases) using a mass spectrometer with a purification and separation line. Gas purification and separation did not exist on the Vicking instrument. Because Paloma includes purification and separation, we expect strong improvement in precision. Ne, Ar and Xe isotope ratios should be obtained with an accuracy of better than 1%. Determination of the presently unknown ^3He/^4He ratio is also awaited from this experiment. Knowledge of noble gas isotopes in Mars atmosphere will allow some insight into major planetary processes such as degassing (^3He/^4He, 40Ar/36Ar, 129Xe/130Xe, 136Xe/130Xe), gravitational escape to space (^3He/^4He, 20Ne/22Ne), hydrodynamic escape and/or impact erosion of the atmosphere (20Ne/22Ne, 21Ne/22Ne, 38Ar/36Ar, Xe isotopes), input of solar wind and galactic comic rays (^3He/^4He, 20Ne/22Ne, 21Ne/22Ne). Comparison with the Earth may also shed light on long standing problems such as the large isotopic mass fractionation of the Xe isotopes and the so-called missing xenon problem. Possible variations of Kr and Xe abundances due to adsorption phenomena related to the climatic cycle will be searched for by measuring along at least one martian year.

Helium isotope enrichment by resonant tunneling through nanoporous graphene bilayers.

PubMed

Mandrà, Salvatore; Schrier, Joshua; Ceotto, Michele

2014-08-21

Graphene is impermeable to gases, but introducing subnanometer pores can allow for selective gas separation. Because graphene is only one atom thick, tunneling can play an important role, especially for low-mass gases such as helium, and this has been proposed as a means of separating (3)He from (4)He. In this paper, we consider the possibility of utilizing resonant tunneling of helium isotopes through nanoporous graphene bilayers. Using a model potential fit to previously reported DFT potential energy surfaces, we calculate the thermal rate constant as a function of interlayer separation using a recently described time-independent method for arbitrary multibarrier potentials. Resonant transmission allows for the total flux rate of (3)He to remain the same as the best-known single-barrier pores but doubles the selectivity with respect to (4)He when the optimal interlayer spacing of 4.6 Å is used. The high flux rate and selectivity are robust against variations of the interlayer spacing and asymmetries in the potential that may occur in experiment.

Solid-state Marx based two-switch voltage modulator for the On-Line Isotope Mass Separator accelerator at the European Organization for Nuclear Research

NASA Astrophysics Data System (ADS)

Redondo, L. M.; Silva, J. Fernando; Canacsinh, H.; Ferrão, N.; Mendes, C.; Soares, R.; Schipper, J.; Fowler, A.

2010-07-01

A new circuit topology is proposed to replace the actual pulse transformer and thyratron based resonant modulator that supplies the 60 kV target potential for the ion acceleration of the On-Line Isotope Mass Separator accelerator, the stability of which is critical for the mass resolution downstream separator, at the European Organization for Nuclear Research. The improved modulator uses two solid-state switches working together, each one based on the Marx generator concept, operating as series and parallel switches, reducing the stress on the series stacked semiconductors, and also as auxiliary pulse generator in order to fulfill the target requirements. Preliminary results of a 10 kV prototype, using 1200 V insulated gate bipolar transistors and capacitors in the solid-state Marx circuits, ten stages each, with an electrical equivalent circuit of the target, are presented, demonstrating both the improved voltage stability and pulse flexibility potential wanted for this new modulator.

The development of a new technical platform to measure soil organic nitrogen cycling processes by microbes

NASA Astrophysics Data System (ADS)

Hu, Yuntao; Richter, Andreas; Wanek, Wolfgang

2016-04-01

Soil organic matter (SOM) decomposition is one of the most important processes of the global nitrogen cycle, having strong implications on soil N availability, terrestrial carbon cycling and soil carbon sequestration. During SOM decomposition low-molecular weight organic nitrogen (LMWON) is released which can be taken up by microbes (and plants). The breakdown of high-molecular weight organic nitrogen (HMWON, e.g. proteins, peptidoglycan, chitin, nucleic acids) represents the bottleneck of soil HMWON decomposition and is performed by extracellular enzymes released mainly by soil microorganisms. Despite that, the current understanding of the controls of these processes is incomplete. The only way to measure gross decomposition rates of these polymers is to use isotope pool dilution (IPD) techniques. In IPD approaches the product pool is isotopically enriched (by e.g. 15N) and the isotope dilution of this pool is measured over time. We have pioneered an IPD for protein and cellulose depolymerization, but IPD approaches for other polymers, specifically for important microbial necromass components such as chitin (fungi) and peptidoglycan (bacteria), or nucleic acids have not yet been developed. Here we present a workflow based on a universally applicable technical platform that allows to estimate the gross depolymerization rate of SOM (HMWON) at the molecular level, using ultra high performance liquid chromatography/high resolution Orbitrap mass spectrometry (UPLC/HRMS) combined with IPD techniques. The necessary isotopically labeled organic polymers (chitin, peptidoglycan and others) are extracted from laboratory bacterial and fungal cultures grown in fully isotopically labeled nutrient media (15N, 13C or both). A purification scheme for the different polymers is currently established. Labeled potential decomposition products (e.g. amino sugars and muropeptides from peptidoglycan, amino sugars and chitooligosaccharides from chitin, nucleotides and nucleosides from nucleic acids) are prepared by enzymatic and/or acid digestion of the polymers. Different UPLC separation columns (Hypercarb, HiliC and C18) make it possible to separate more than 100 related monomers and oligomers produced during polymer decomposition, a prerequisite for analyzing the concentrations and isotope kinetics of decomposition products in complex soil samples. The benchtop Orbitrap mass analyzer has a nominal mass resolving power of 100,000 (FWHM at m/z 200), which enables us to separate compounds that are 13C- and 15N-labelled (mass difference: 0.00632) in the same compound, allowing tracing carbon and nitrogen isotopes in the same compound in IPD experiments. With the accurate masses, retention times and the isotopic pattern we can quantify and qualify the target decomposition products and their isotope kinetics during soil incubation experiments. This will enable us to estimate in situ decomposition rates of the major organic nitrogen polymers in soils, allowing new insights into the major controls of the most important step in soil organic nitrogen recycling.

An isotope hydrology study of the Kilauea volcano area, Hawaii

USGS Publications Warehouse

Scholl, M.A.; Ingebritsen, S.E.; Janik, C.J.; Kauahikaua, J.P.

1995-01-01

Isotope tracer methods were used to determine flow paths, recharge areas, and relative age for ground water in the Kilauea volcano area on the Island of Hawaii. Stable isotopes in rainfall show three distinct isotopic gradients with elevation, which are correlated with trade-wind, rain shadow, and high-elevation climatological patterns. Temporal variations in isotopic composition of precipitation are controlled more by the frequency of large storms than b.y seasonal temperature fluctuations. Consistency in results between two separate areas with rainfall caused by tradewinds and thermally-driven upslope airflow suggests that isotopic gradients with elevation may be similar on other islands in the tradewind belt, especially the other Hawaiian Islands, which have similar climatology and temperature lapse rates. Areal contrasts in ground-water stable isotopes and tritium indicate that the volcanic ri~ zones compartmentalize the regional ground-water system. Tritium levels in ground water within and downgradient of Kilauea's ri~ zones indicate relatively long residence times. Part of Kilauea's Southwest Ri~ Zone appears to act as a conduit for water from higher elevation, but there is no evidence for extensive down-ri~ flow in the lower East Ri~ Zone.

Simultaneous stable carbon isotopic analysis of wine glycerol and ethanol by liquid chromatography coupled to isotope ratio mass spectrometry.

PubMed

Cabañero, Ana I; Recio, Jose L; Rupérez, Mercedes

2010-01-27

A novel procedure was established for the simultaneous characterization of wine glycerol and ethanol (13)C/(12)C isotope ratio, using liquid chromatography/isotope ratio mass spectrometry (LC-IRMS). Several parameters influencing separation of glycerol and ethanol from wine matrix were optimized. Results obtained for 35 Spanish samples exposed no significant differences and very strong correlations (r = 0.99) between the glycerol (13)C/(12)C ratios obtained by an alternative method (gas chromatography/isotope ratio mass spectrometry) and the proposed new methodology, and between the ethanol (13)C/(12)C ratios obtained by the official method (elemental analyzer/isotope ratio mass spectrometry) and the proposed new methodology. The accuracy of the proposed method varied from 0.01 to 0.19 per thousand, and the analytical precision was better than 0.25 per thousand. The new developed LC-IRMS method it is the first isotopic method that allows (13)C/(12)C determination of both analytes in the same run directly from a liquid sample with no previous glycerol or ethanol isolation, overcoming technical difficulties associated with complex sample treatment and improving in terms of simplicity and speed.

Application of Stable Isotope-Assisted Metabolomics for Cell Metabolism Studies

PubMed Central

You, Le; Zhang, Baichen; Tang, Yinjie J.

2014-01-01

The applications of stable isotopes in metabolomics have facilitated the study of cell metabolisms. Stable isotope-assisted metabolomics requires: (1) properly designed tracer experiments; (2) stringent sampling and quenching protocols to minimize isotopic alternations; (3) efficient metabolite separations; (4) high resolution mass spectrometry to resolve overlapping peaks and background noises; and (5) data analysis methods and databases to decipher isotopic clusters over a broad m/z range (mass-to-charge ratio). This paper overviews mass spectrometry based techniques for precise determination of metabolites and their isotopologues. It also discusses applications of isotopic approaches to track substrate utilization, identify unknown metabolites and their chemical formulas, measure metabolite concentrations, determine putative metabolic pathways, and investigate microbial community populations and their carbon assimilation patterns. In addition, 13C-metabolite fingerprinting and metabolic models can be integrated to quantify carbon fluxes (enzyme reaction rates). The fluxome, in combination with other “omics” analyses, may give systems-level insights into regulatory mechanisms underlying gene functions. More importantly, 13C-tracer experiments significantly improve the potential of low-resolution gas chromatography-mass spectrometry (GC-MS) for broad-scope metabolism studies. We foresee the isotope-assisted metabolomics to be an indispensable tool in industrial biotechnology, environmental microbiology, and medical research. PMID:24957020

Abstracts of the 24th international isotope society (UK group) symposium: synthesis and applications of labelled compounds 2015.

PubMed

Aigbirhio, F I; Allwein, S; Anwar, A; Atzrodt, J; Audisio, D; Badman, G; Bakale, R; Berthon, F; Bragg, R; Brindle, K M; Bushby, N; Campos, S; Cant, A A; Chan, M Y T; Colbon, P; Cornelissen, B; Czarny, B; Derdau, V; Dive, V; Dunscombe, M; Eggleston, I; Ellis-Sawyer, K; Elmore, C S; Engstrom, P; Ericsson, C; Fairlamb, I J S; Georgin, D; Godfrey, S P; He, L; Hickey, M J; Huscroft, I T; Kerr, W J; Lashford, A; Lenz, E; Lewinton, S; L'Hermite, M M; Lindelöf, Å; Little, G; Lockley, W J S; Loreau, O; Maddocks, S; Marguerit, M; Mirabello, V; Mudd, R J; Nilsson, G N; Owens, P K; Pascu, S I; Patriarche, G; Pimlott, S L; Pinault, M; Plastow, G; Racys, D T; Reif, J; Rossi, J; Ruan, J; Sarpaki, S; Sephton, S M; Simonsson, R; Speed, D J; Sumal, K; Sutherland, A; Taran, F; Thuleau, A; Wang, Y; Waring, M; Watters, W H; Wu, J; Xiao, J

2016-04-01

The 24th annual symposium of the International Isotope Society's United Kingdom Group took place at the Møller Centre, Churchill College, Cambridge, UK on Friday 6th November 2015. The meeting was attended by 77 delegates from academia and industry, the life sciences, chemical, radiochemical and scientific instrument suppliers. Delegates were welcomed by Dr Ken Lawrie (GlaxoSmithKline, UK, chair of the IIS UK group). The subsequent scientific programme consisted of oral presentations, short 'flash' presentations in association with particular posters and poster presentations. The scientific areas covered included isotopic synthesis, regulatory issues, applications of labelled compounds in imaging, isotopic separation and novel chemistry with potential implications for isotopic synthesis. Both short-lived and long-lived isotopes were represented, as were stable isotopes. The symposium was divided into a morning session chaired by Dr Rebekka Hueting (University of Oxford, UK) and afternoon sessions chaired by Dr Sofia Pascu (University of Bath, UK) and by Dr Alan Dowling (Syngenta, UK). The UK meeting concluded with remarks from Dr Ken Lawrie (GlaxoSmithKline, UK). Copyright © 2016 John Wiley & Sons, Ltd.

Constraints on post-depositional isotope modifications in East Antarctic firn from analysing temporal changes of isotope profiles

NASA Astrophysics Data System (ADS)

Münch, Thomas; Kipfstuhl, Sepp; Freitag, Johannes; Meyer, Hanno; Laepple, Thomas

2017-09-01

The isotopic composition of water in ice sheets is extensively used to infer past climate changes. In low-accumulation regions their interpretation is, however, challenged by poorly constrained effects that may influence the initial isotope signal during and after deposition of the snow. This is reflected in snow-pit isotope data from Kohnen Station, Antarctica, which exhibit a seasonal cycle but also strong interannual variations that contradict local temperature observations. These inconsistencies persist even after averaging many profiles and are thus not explained by local stratigraphic noise. Previous studies have suggested that post-depositional processes may significantly influence the isotopic composition of East Antarctic firn. Here, we investigate the importance of post-depositional processes within the open-porous firn (≳ 10 cm depth) at Kohnen Station by separating spatial from temporal variability. To this end, we analyse 22 isotope profiles obtained from two snow trenches and examine the temporal isotope modifications by comparing the new data with published trench data extracted 2 years earlier. The initial isotope profiles undergo changes over time due to downward advection, firn diffusion and densification in magnitudes consistent with independent estimates. Beyond that, we find further modifications of the original isotope record to be unlikely or small in magnitude (≪ 1 ‰ RMSD). These results show that the discrepancy between local temperatures and isotopes most likely originates from spatially coherent processes prior to or during deposition, such as precipitation intermittency or systematic isotope modifications acting on drifting or loose surface snow.

Carbon isotope ratios and isotopic correlations between components in fruit juices

NASA Astrophysics Data System (ADS)

Wierzchnicki, Ryszard

2013-04-01

Nowadays food products are defined by geographical origin, method of production and by some regulations concerning terms of their authenticity. Important data for confirm the authenticity of product are providing by isotopic methods of food control. The method checks crucial criteria which characterize the authenticity of inspected product. The European Union Regulations clearly show the tendency for application of the isotopic methods for food authenticity control (wine, honey, juice). The aim of the legislation steps is the protection of European market from possibility of the commercial frauds. Method of isotope ratio mass spectrometry is very effective tool for the use distinguishably the food products of various geographical origin. The basic problem for identification of the sample origin is the lack of databases of isotopic composition of components and information about the correlations of the data. The subject of the work was study the isotopic correlations existing between components of fruits. The chemical and instrumental methods of separation: water, sugars, organic acids and pulp from fruit were implemented. IRMS technique was used to measure isotopic composition of samples. The final results for original samples of fruits (apple, strawberry etc.) will be presented and discussed. Acknowledgement: This work was supported by the Polish Ministry of Science and Higher Education under grant NR12-0043-10/2010.

Production of platinum radioisotopes at Brookhaven Linac Isotope Producer (BLIP)

NASA Astrophysics Data System (ADS)

Smith, Suzanne V.; McCutchan, Elizabeth; Gürdal, Gülhan; Lister, Christopher; Muench, Lisa; Nino, Michael; Sonzogni, Alexandro; Herman, Michal; Nobre, Gustavo; Cullen, Chris; Chillery, Thomas; Chowdury, Partha; Harding, Robert

2017-09-01

The accelerator production of platinum isotopes was investigated at the Brookhaven Linac Isotope Producer (BLIP). In this study high purity natural platinum foils were irradiated at 53.2, 65.7, 105.2, 151.9, 162.9 and 173.3.MeV. The irradiated foils were digested in aqua regia and then converted to their hydrochloride salt with concentrated hydrochloric acid before analyzing by gamma spectrometry periodically for at least 10 days post end of bombardment. A wide range of platinum (Pt), gold (Au) and iridium (Ir) isotopes were identified. Effective cross sections at BLIP for Pt-188, Pt-189, Pt-191 and Pt-195m were compared to literature and theoretical cross sections determined using Empire-3.2. The majority of the effective cross sections (<70 MeV) confirm those reported in the literature. While the absolute values of the theoretical cross sections were up to a factor of 3 lower, Empire 3.2 modeled thresholds and maxima correlated well with experimental values. Preliminary evaluation into a rapid separation of Pt isotopes from high levels of Ir and Au isotopes proved to be a promising approach for large scale production. In conclusion, this study demonstrated that with the use of isotopically enriched target material accelerator production of selected platinum isotopes is feasible over a wide proton energy range.

Development of fast-release solid catchers for rare isotopes

NASA Astrophysics Data System (ADS)

Nolen, Jerry; Greene, John; Elam, Jeffrey; Mane, Anil; Sampathkumaran, Uma; Winter, Raymond; Hess, David; Mushfiq, Mohammad; Stracener, Daniel; Wiendenhoever, Ingo

2015-04-01

Porous solid catchers of rare isotopes are being developed for use at high power heavy ion accelerator facilities such as RIKEN, FRIB, and RISP. Compact solid catchers are complementary to helium gas catchers for parasitic harvesting of rare isotopes in the in-flight separators. They are useful for short lived isotopes for basic nuclear physics research and longer-lived isotopes for off-line applications. Solid catchers can operate effectively with high intensity secondary beams, e.g. >> 1E10 atoms/s with release times as short as 10-100 milliseconds. A new method using a very sensitive and efficient RGA has been commissioned off-line at Argonne and is currently being shipped to Florida State University for in-beam measurements of the release curves using stable beams. The same porous solid catcher technology is also being evaluated for use in targets for the production of medical isotopes such as 211-At. Research supported by the U.S. DOE Office of Nuclear Physics under the SBIR Program and Contract # DE-AC02-06CH11357 and a University of Chicago Comprehensive Cancer Center/ANL Pilot Project.

Isotopic evidence bearing on Late Triassic extinction events, Queen Charlotte Islands, British Columbia, and implications for the duration and cause of the Triassic/Jurassic mass extinction

USGS Publications Warehouse

Ward, P.D.; Garrison, G.H.; Haggart, J.W.; Kring, D.A.; Beattie, M.J.

2004-01-01

Stable isotope analyses of Late Triassic to earliest Jurassic strata from Kennecott Point in the Queen Charlotte Islands, British Columbia, Canada shows the presence of two distinct and different organic carbon isotope anomalies at the Norian/Rhaetian and Rhaetian/Hettangian (=Triassic/Jurassic) stage boundaries. At the older of these boundaries, which is marked by the disappearance of the bivalve Monotis, the isotope record shows a series of short-lived positive excursions toward heavier values. Strata approaching this boundary show evidence of increasing anoxia. At the higher boundary, marked by the disappearance of the last remaining Triassic ammonites and over 50 species of radiolarians, the isotopic pattern consists of a series of short duration negative anomalies. The two events, separated by the duration of the Rhaetian age, comprise the end-Triassic mass extinction. While there is no definitive evidence as to cause, the isotopic record does not appear similar to that of the impact-caused Cretaceous/Tertiary boundary extinction. ?? 2004 Published by Elsevier B.V.

Isotopic excesses of proton-rich nuclei related to space weathering observed in a gas-rich meteorite Kapoeta

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hidaka, Hiroshi; Yoneda, Shigekazu, E-mail: hidaka@hiroshima-u.ac.jp, E-mail: s-yoneda@kahaku.go.jp

2014-05-10

The idea that solar system materials were irradiated by solar cosmic rays from the early Sun has long been suggested, but is still questionable. In this study, Sr, Ba, Ce, Nd, Sm, and Gd isotopic compositions of sequential acid leachates from the Kapoeta meteorite (howardite) were determined to find systematic and correlated variations in their isotopic abundances of proton-rich nuclei, leading to an understanding of the irradiation condition by cosmic rays. Significantly large excesses of proton-rich isotopes (p-isotopes), {sup 84}Sr, {sup 130}Ba, {sup 132}Ba, {sup 136}Ce, {sup 138}Ce, and {sup 144}Sm, were observed, particularly in the first chemical separate, whichmore » possibly leached out of the very shallow layer within a few μm from the surface of regolith grains in the sample. The results reveal the production of p-isotopes through the interaction of solar cosmic rays with the superficial region of the regolith grains before the formation of the Kapoeta meteorite parent body, suggesting strong activity in the early Sun.« less

Reduction of Solvent Effect in Reverse Phase Gradient Elution LC-ICP-MS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sullivan, Patrick Allen

2005-12-17

Quantification in liquid chromatography (LC) is becoming very important as more researchers are using LC, not as an analytical tool itself, but as a sample introduction system for other analytical instruments. The ability of LC instrumentation to quickly separate a wide variety of compounds makes it ideal for analysis of complex mixtures. For elemental speciation, LC is joined with inductively coupled plasma mass spectrometry (ICP-MS) to separate and detect metal-containing, organic compounds in complex mixtures, such as biological samples. Often, the solvent gradients required to perform complex separations will cause matrix effects within the plasma. This limits the sensitivity ofmore » the ICP-MS and the quantification methods available for use in such analyses. Traditionally, isotope dilution has been the method of choice for LC-ICP-MS quantification. The use of naturally abundant isotopes of a single element in quantification corrects for most of the effects that LC solvent gradients produce within the plasma. However, not all elements of interest in speciation studies have multiple naturally occurring isotopes; and polyatomic interferences for a given isotope can develop within the plasma, depending on the solvent matrix. This is the case for reverse phase LC separations, where increasing amounts of organic solvent are required. For such separations, an alternative to isotope dilution for quantification would be is needed. To this end, a new method was developed using the Apex-Q desolvation system (ESI, Omaha, NE) to couple LC instrumentation with an ICP-MS device. The desolvation power of the system allowed greater concentrations of methanol to be introduced to the plasma prior to destabilization than with direct methanol injection into the plasma. Studies were performed, using simulated and actual linear methanol gradients, to find analyte-internal standard (AIS) pairs whose ratio remains consistent (deviations {+-} 10%) over methanol concentration ranges of 5%-35% (simulated) and 8%-32% (actual). Quadrupole (low resolution) and sector field (high resolution) ICP-MS instrumentation were utilized in these studies. Once an AIS pair is determined, quantification studies can be performed. First, an analysis is performed by adding both elements of the AIS pair post-column while performing the gradient elution without sample injection. A comparison of the ratio of the measured intensities to the atomic ratio of the two standards is used to determine a correction factor that can be used to account for the matrix effects caused by the mobile phase. Then, organic and/or biological molecules containing one of the two elements in the AIS pair are injected into the LC column. A gradient method is used to vary the methanol-water mixture in the mobile phase and to separate out the compounds in a given sample. A standard solution of the second ion in the AIS pair is added continuously post-column. By comparing the ratio of the measured intensities to the atomic ratio of the eluting compound and internal standard, the concentration of the injected compound can be determined.« less

SERVOMOTOR CONTROL SYSTEM

DOEpatents

MacNeille, S.M.

1958-12-01

Control systems for automatic positioning of an electric motor operated vapor valve are described which is operable under the severe conditions existing in apparatus for electro-magnetlcally separating isotopes. In general, the system includes a rotor for turning the valve comprising two colls mounted mutually perpendicular to each other and also perpendicular to the magnetic field of the isotope separating apparatus. The coils are furnished with both a-c and d- c current by assoclate control circuitry and a position control is provided for varying the ratlo of the a-c currents in the coils and at the same time, but in an inverse manner, the ratio between the d-c currents in the coils is varied. With the present system the magnitude of the motor torque is constant for all valves of the rotor orientatlon angle.

Exclusive quasi-free proton knockout from oxygen isotopes at intermediate energies

NASA Astrophysics Data System (ADS)

Kawase, Shoichiro; Uesaka, Tomohiro; Tang, Tsz Leung; Beaumel, Didier; Dozono, Masanori; Fukunaga, Taku; Fujii, Toshihiko; Fukuda, Naoki; Galindo-Uribarri, Alfredo; Hwang, Sanghoon; Inabe, Naoto; Kawabata, Takahiro; Kawahara, Tomomi; Kim, Wooyoung; Kisamori, Keiichi; Kobayashi, Motoki; Kubo, Toshiyuki; Kubota, Yuki; Kusaka, Kensuke; Lee, Cheongsoo; Maeda, Yukie; Matsubara, Hiroaki; Michimasa, Shin'ichiro; Miya, Hiroyuki; Noro, Tetsuo; Nozawa, Yuki; Obertelli, Alexandre; Ogata, Kazuyuki; Ota, Shinsuke; Padilla-Rodal, Elizabeth; Sakaguchi, Satoshi; Sakai, Hideyuki; Sasano, Masaki; Shimoura, Susumu; Stepanyan, Samvel; Suzuki, Hiroshi; Suzuki, Tomokazu; Takaki, Motonobu; Takeda, Hiroyuki; Tamii, Atsushi; Tokieda, Hiroshi; Wakasa, Tomotsugu; Wakui, Takashi; Yako, Kentaro; Yasuda, Jumpei; Yanagisawa, Yoshiyuki; Yokoyama, Rin; Yoshida, Kazuki; Yoshida, Koichi; Zenihiro, Juzo

2018-02-01

The dependence of the single-particle strength on the difference between proton and neutron separation energies is studied for oxygen isotopes in a wide range of isospins. The cross sections of the quasi-free (p,2p) reaction on ^{14,16,18,22,24}O were measured at intermediate energies. The measured cross sections are compared to predictions based on the distorted wave impulse approximation and shell-model psd valence-space spectroscopic factors. The reduction factors, which are the ratio of the experimental cross sections to the theoretical predictions, show no apparent dependence on the proton-neutron separation energy difference. The result is compatible with the result of the (e,e^'p) reaction on stable targets and with the predictions of recent ab initio calculations.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bigeleisen, J.

In tribute to Harold Urey, the author cites Urey's accomplishments as a scientist and public servant and gives insight of the man. Some of his accomplishments in science are: discovered deuterium for which he received the Nobel prize in 1934; worked with Rittenberg and Greiff on the theory and calculation of the differences in the thermodynamic properties of isotopic compounds; with Thode, Hutchison and others, separated the isotopes of the light elements by chemical methods on a laboratory scale; during World War II headed the Substitute Alloy Materials Laboratories of Columbia University where his group developed industrial scale processes formore » the separation of /sup 2/H, /sup 10/B, and /sup 235/U; with his associates developed the /sup 18/O paleotemperature scale; made fundamental contributions to a widely accepted theory of the origin of the earth. (ATT)« less

Separated isotopes: vital tools for science and medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1982-01-01

Deliberations and conclusions of a Workshop on Stable Isotopes and Derived Radioisotopes organized by the Subcommittee on Nuclear and Radiochemistry of the National Research Council's Committee on Chemical Sciences at the request of the Department of Energy (DOE) are summarized. The workshop was jointly supported by the National Institutes of Health and DOE's Office of Basic Energy Sciences. An overview with three recommendations resulting from the Workshop is followed by reports of the four Workshop panels. Background papers were prepared by individuals on the Steering Committee and made available to all participants prior to the Workshop. They are reproduced asmore » Appendixes 3 to 8. Short reports on alternate separation techniques were presented at the Workshop and are reproduced in Appendixes 9 to 11.« less

Multiple taxon multiple locality approach to providing oxygen isotope evidence for warm-blooded theropod dinosaurs

NASA Astrophysics Data System (ADS)

Fricke, Henry C.; Rogers, Raymond R.

2000-09-01

Oxygen isotope ratios of fossil remains of coexisting taxa from several different localities can be used to help investigate dinosaur thermoregulation. Focusing on the Late Cretaceous, oxygen isotope ratios of crocodile tooth enamel from four separate localities exhibit less of a decrease with latitude than do ratios of tooth enamel from coexisting theropod dinosaurs. A shallower latitudinal gradient for crocodiles is consistent with how oxygen isotope ratios should vary for heterothermic animals having body temperatures coupled with their environments (“cold blooded”), while a steeper gradient for theropods is consistent with how these ratios should vary for homeothermic animals having constant body temperatures independent of their environments (“warm blooded”). This inferred homoethermy in theropods is likely due to higher rates of metabolic heat production relative to crocodiles and is not an artifact of body size.

Observation of New Neutron-rich Isotopes among Fission Fragments from In-flight Fission of 345 MeV/nucleon 238U: Search for New Isotopes Conducted Concurrently with Decay Measurement Campaigns

NASA Astrophysics Data System (ADS)

Shimizu, Yohei; Kubo, Toshiyuki; Fukuda, Naoki; Inabe, Naohito; Kameda, Daisuke; Sato, Hiromi; Suzuki, Hiroshi; Takeda, Hiroyuki; Yoshida, Koichi; Lorusso, Giuseppe; Watanabe, Hiroshi; Simpson, Gary S.; Jungclaus, Andrea; Baba, Hidetada; Browne, Frank; Doornenbal, Pieter; Gey, Guillaunme; Isobe, Tadaaki; Li, Zhihuan; Nishimura, Shunji; Söderström, Pär-Anders; Sumikama, Toshiyuki; Taprogge, Jan; Vajta, Zsolt; Wu, Jin; Xu, Zhengyu; Odahara, Atsuko; Yagi, Ayumi; Nishibata, Hiroki; Lozeva, Radomira; Moon, Changbum; Jung, HyoSoon

2018-01-01

The search for new isotopes using the in-flight fission of a 238U beam has been conducted concurrently with decay measurements, during the so-called EURICA campaigns, at the RIKEN Nishina Center RI Beam Factory. Fission fragments were analyzed and identified in flight using the BigRIPS separator. We have identified the following 36 new neutron-rich isotopes: 104Rb, 113Zr, 116Nb, 118,119Mo, 121,122Tc, 125Ru, 127,128Rh, 129,130,131Pd, 132Ag, 134Cd, 136,137In, 139,140Sn, 141,142Sb, 144,145Te, 146,147I, 149,150Xe, 149,150,151Cs, 153,154Ba, and 154,155,156,157La.

New mass anchor points for neutron-deficient heavy nuclei from direct mass measurements of radium and actinium isotopes

NASA Astrophysics Data System (ADS)

Rosenbusch, M.; Ito, Y.; Schury, P.; Wada, M.; Kaji, D.; Morimoto, K.; Haba, H.; Kimura, S.; Koura, H.; MacCormick, M.; Miyatake, H.; Moon, J. Y.; Morita, K.; Murray, I.; Niwase, T.; Ozawa, A.; Reponen, M.; Takamine, A.; Tanaka, T.; Wollnik, H.

2018-06-01

The masses of the exotic isotopes Ac-214210 and Ra-214210 have been measured with a multireflection time-of-flight mass spectrograph. These isotopes were obtained in flight as fusion-evaporation products behind the gas-filled recoil ion separator GARIS-II at RIKEN. The new direct mass measurements serve as an independent and direct benchmark for existing α -γ spectroscopy data in this mass region. Further, new mass anchor points are set for U and Np nuclei close to the N =126 shell closure for a future benchmark of the Z =92 subshell for neutron-deficient heavy isotopes. Our mass results are in general in good agreement with the previously indirectly determined mass values. Together with the measurement data, reasons for possible mass ambiguities from decay-data links between ground states are discussed.

Performance and limits of liquid chromatography isotope ratio mass spectrometry system for halogenated compounds

NASA Astrophysics Data System (ADS)

Gilevska, Tetyana; Gehre, Matthias; Richnow, Hans

2014-05-01

Compound Specific Isotope Analysis (CSIA) has been an important step for the assessment of the origin and fate of compounds in environmental science.[1] Biologically or pharmaceutically important compounds often are not amenable for gas chromatographic separation because of high polarity and lacking volatility, thermostability. In 2004 liquid chromatography isotope ratio mass spectrometry (LC-IRMS) became commercially available. LC-IRMS system intent a quantitative conversion of analytes separation into CO2 via wet oxidation with sodium persulfate in the presence of phosphoric acid while analytes are still dissolved in the aqueous liquid phase.[2] The aim of this study is to analyze the oxidation capacity of the interface of the LC-IRMS system and determine which parameters could improve oxidation of compounds which are resistant to persulfate oxidation. Oxidation capacity of the liquid chromatography isotope ratio mass spectrometry system was tested with halogenated acetic acid and a set of aromatic compounds with different substitutes. Acetic acid (AA) was taken as a model compound for complete oxidation and compared to the oxidation of other analytes on a molar basis. Correct values were obtained for di- and mono chlorinated and fluorinated and also for tribrominated acetic acid and for all studied aromatic compounds. Incomplete oxidation for trichloroacetic (TCAA) and trifluoroacetic (TFAA) acid was revealed with lower recovery compared to acetic acid and isotope fractionation leading to depleted carbon isotope composition compared to values obtained with an elementary analyzer connected to an isotope mass spectrometer Several optimization steps were tried in order to improve the oxidation of TCAA and TFAA: (i) increasing the concentration of the oxidizing agent, (ii) variation of flow rate of the oxidizing and acid solution, (iii) variation of flow rate of liquid chromatography pump (iv) addition of a catalyzer. These modifications lead to longer reaction time in the coil and increase in the concentration of radical but complete combustion of highly chlorinated or fluorinated compounds was not achieved. Due to these findings the limit for a LC-IRMS system for similar structure compounds can be predicted. 1. Elsner, M., et al., Current challenges in compound-specific stable isotope analysis of environmental organic contaminants. Analytical and Bioanalytical Chemistry, 2012. 403(9): p. 2471-2491. 2. Krummen, M., et al., A new concept for isotope ratio monitoring liquid chromatography/mass spectrometry. Rapid Communications in Mass Spectrometry, 2004. 18(19): p. 2260-2266.

Contrasting Effects of Carbon and Sulfur on Fe-Isotope Fractionation between Metal and Silicate Melt during Planetary Core Formation

NASA Astrophysics Data System (ADS)

Elardo, S. M.; Shahar, A.

2015-12-01

There are numerous studies that show well-resolved Fe isotope fractionations in igneous materials from different planetary bodies. Potential explanations for these fractionations include a non-chondritic bulk planetary Fe isotopic composition, and equilibrium fractionation between Fe-alloys or minerals and silicate melts during planetary differentiation, mantle melting, or fractional crystallization. This is further complicated by the fact that these processes are not mutually exclusive, making the interpretation of Fe isotope data a complex task. Here we present new experimental results investigating the effect of C on Fe isotope fractionation between molten peridotite and an Fe-alloy. Experiments were conducted at 1 GPa and 1850° C for 0.5 - 3 hours on a mixture of an 54Fe-spiked peridotite and Fe-metal with and without Ni metal in an end-loaded piston cylinder at the Geophysical Laboratory. Carbon saturation was achieved with a graphite capsule, and resulted in C contents of the Fe-alloy in our experiments ranging from 3.8 - 4.9 wt. %. The metal and silicate phases from half of each experiment were separated manually and dissolved in concentrated acids. Iron was separated from matrix elements by anion exchange chromatagraphy. Iron-isotopic compositions were determined with the Nu Plasma II MC-ICP-MS at GL. The other half of each experiment was used for quantitative microbeam analysis. Equilibrium was assessed with a time series and the three-isotope exchange method. The Ni-free experiments resulted in no resolvable Fe isotope fractionation between the Fe-C-alloy and molten silicate. This is in contrast to the results of Shahar et al. (2015) which showed a fractionation for Δ57Fe of ~0.18 ‰ between a peridotite and an Fe-alloy with a similar S abundance to C in these experiments. The one experiment thus far that contained Ni (~4 wt. % in the alloy) showed a resolvable fractionation between the Fe-Ni-C alloy and silicate of ~0.10 ‰. Shahar et al. found a similar magnitude fractionation to our Ni bearing experiment in experiments with no C or S. The difference in temperature (1650° C in Shahar et al. vs. 1850° C here) may be partially responsible for these discrepancies. Ongoing experiments will further investigate the effects of C and other light elements on Fe isotope fractionation during core segregation.

Production and recovery of Americium-241

DOE Office of Scientific and Technical Information (OSTI.GOV)

Navratil, J.D.

1984-01-01

Americium-241, one of the most useful actinide isotopes, is produced as a by-product of plutonium scrap recovery operations. Rocky Flats (RF) has supplied high-purity americium oxide to the US Department of Energy's Isotope Pool since 1962. Over the years, the evolving separation and purification processes have included such diverse operations as aqueous precipitation, ion exchange, and both molten-salt and organic-solvent extraction. A review is presented of the production and recovery processes of americium-241. 5 references.

Current developments with TRIUMF's titanium-sapphire laser based resonance ionization laser ion source. An overview

NASA Astrophysics Data System (ADS)

Lassen, J.; Li, R.; Raeder, S.; Zhao, X.; Dekker, T.; Heggen, H.; Kunz, P.; P. Levy, C. D.; Mostanmand, M.; Teigelhöfer, A.; Ames, F.

2017-11-01

Developments at TRIUMF's isotope separator and accelerator (ISAC) resonance ionization laser ion source (RILIS) in the past years have concentrated on increased reliability for on-line beam delivery of radioactive isotopes to experiments, as well as increasing the number of elements available through resonance ionization and searching for ionization schemes with improved efficiency. The current status of these developments is given with a list of two step laser ionization schemes implemented recently.

Beam dynamics simulations of post low energy beam transport section in RAON heavy ion accelerator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jin, Hyunchang, E-mail: hcjin@ibs.re.kr; Jang, Ji-Ho; Jang, Hyojae

RAON (Rare isotope Accelerator Of Newness) heavy ion accelerator of the rare isotope science project in Daejeon, Korea, has been designed to accelerate multiple-charge-state beams to be used for various science programs. In the RAON accelerator, the rare isotope beams which are generated by an isotope separation on-line system with a wide range of nuclei and charges will be transported through the post Low Energy Beam Transport (LEBT) section to the Radio Frequency Quadrupole (RFQ). In order to transport many kinds of rare isotope beams stably to the RFQ, the post LEBT should be devised to satisfy the requirement ofmore » the RFQ at the end of post LEBT, simultaneously with the twiss parameters small. We will present the recent lattice design of the post LEBT in the RAON accelerator and the results of the beam dynamics simulations from it. In addition, the error analysis and correction in the post LEBT will be also described.« less

High-precision optical measurements of 13C/12C isotope ratios in organic compounds at natural abundance

PubMed Central

Zare, Richard N.; Kuramoto, Douglas S.; Haase, Christa; Tan, Sze M.; Crosson, Eric R.; Saad, Nabil M. R.

2009-01-01

A continuous-flow cavity ring-down spectroscopy (CRDS) system integrating a chromatographic separation technique, a catalytic combustor, and an isotopic 13C/12C optical analyzer is described for the isotopic analysis of a mixture of organic compounds. A demonstration of its potential is made for the geochemically important class of short-chain hydrocarbons. The system proved to be linear over a 3-fold injection volume dynamic range with an average precision of 0.95‰ and 0.67‰ for ethane and propane, respectively. The calibrated accuracy for methane, ethane, and propane is within 3‰ of the values determined using isotope ratio mass spectrometry (IRMS), which is the current method of choice for compound-specific isotope analysis. With anticipated improvements, the low-cost, portable, and easy-to-use CRDS-based instrumental setup is poised to evolve into a credible challenge to the high-cost and complex IRMS-based technique. PMID:19564619

High-spin level structure and Ground-state phase transition in the odd-mass 103-109Rh isotopes in the framework of exactly solvable sdg interacting boson-fermion model

NASA Astrophysics Data System (ADS)

Ghapanvari, M.; Ghorashi, A. H.; Ranjbar, Z.; Jafarizadeh, M. A.

2018-03-01

In this article, the negative-parity states in the odd-mass 103 - 109Rh isotopes in terms of the sd and sdg interacting-boson fermion models were studied. The transitional interacting boson-fermion model Hamiltonians in sd and sdg-IBFM versions based on affine SU (1 , 1) Lie Algebra were employed to describe the evolution from the spherical to deformed gamma unstable shapes along with the chain of Rh isotopes. In this method, sdg-IBFM Hamiltonian, which is a three level pairing Hamiltonian was determined easily via the exactly solvable method. Some observables of the shape phase transitions such as energy levels, the two neutron separation energies, signature splitting of the γ-vibrational band, the α-decay and double β--decay energies were calculated and examined for these isotopes. The present calculation correctly reproduces the spherical to gamma-soft phase transition in the Rh isotopes. Some comparisons were made with sd-IBFM.

Physics overview of AVLIS

NASA Astrophysics Data System (ADS)

Solarz, R. W.

1985-02-01

Atomic vapor laster isotope separation (AVLIS) represents the largest-scale potential application of tunable lasers that has received serious attention. The underlying physical principles were identified and optimized, the major technology components were developed, and the integrated enrichment performance of the process was tested. The central physical processes are outlined, progress to date on the technology elements is reviewed, and scaling laws are fomulated. Two primary applications are the production of light-water reactor fuel and the conversion of fuel-grade plutonium to weapons-grade material. A variety of applications exist that all potentially use a common base of AVLIS technology. These include missions such as the enrichment of mercury isotopes to improve fluorescent lamp efficiency, the enrichment of iodine isotopes for medical isotope use, and the cleanup of strontium from defense waste for recovering strontium isotopes for radiothermal mechanical generators. The ability to radidly assess the economic and technical feasibility of each mission is derived from the general applicability of AVLIS physics and AVLIS technology.

Characterization of diesel fuel by chemical separation combined with capillary gas chromatography (GC) isotope ratio mass spectrometry (IRMS).

PubMed

Harvey, Scott D; Jarman, Kristin H; Moran, James J; Sorensen, Christina M; Wright, Bob W

2012-09-15

The purpose of this study was to perform a preliminary investigation of compound-specific isotope analysis (CSIA) of diesel fuels to evaluate whether the technique could distinguish diesel samples from different sources/locations. The ability to differentiate or correlate diesel samples could be valuable for discovering fuel tax evasion schemes or for environmental forensic studies. Two urea adduction-based techniques were used to isolate the n-alkanes from the fuel. Both carbon isotope ratio (δ(13)C) and hydrogen isotope ratio (δD) values for the n-alkanes were then determined by CSIA in each sample. The samples investigated had δ(13)C values that ranged from -30.1‰ to -26.8‰, whereas δD values ranged from -83‰ to -156‰. Plots of δD versus δ(13)C with sample n-alkane points connected in order of increasing carbon number gave well-separated clusters with characteristic shapes for each sample. Principal components analysis (PCA) with δ(13)C, δD, or combined δ(13)C and δD data was applied to extract the maximum information content. PCA scores plots could clearly differentiate the samples, thereby demonstrating the potential of this approach for distinguishing (e.g., fingerprinting) fuel samples using δ(13)C and δD values. Copyright © 2012 Elsevier B.V. All rights reserved.

Rapid determination of actinides in seawater samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.

2014-03-09

A new rapid method for the determination of actinides in seawater samples has been developed at the Savannah River National Laboratory. The actinides can be measured by alpha spectrometry or inductively-coupled plasma mass spectrometry. The new method employs novel pre-concentration steps to collect the actinide isotopes quickly from 80 L or more of seawater. Actinides are co-precipitated using an iron hydroxide co-precipitation step enhanced with Ti +3 reductant, followed by lanthanum fluoride co-precipitation. Stacked TEVA Resin and TRU Resin cartridges are used to rapidly separate Pu, U, and Np isotopes from seawater samples. TEVA Resin and DGA Resin were usedmore » to separate and measure Pu, Am and Cm isotopes in seawater volumes up to 80 L. This robust method is ideal for emergency seawater samples following a radiological incident. It can also be used, however, for the routine analysis of seawater samples for oceanographic studies to enhance efficiency and productivity. In contrast, many current methods to determine actinides in seawater can take 1–2 weeks and provide chemical yields of ~30–60 %. This new sample preparation method can be performed in 4–8 h with tracer yields of ~85–95 %. By employing a rapid, robust sample preparation method with high chemical yields, less seawater is needed to achieve lower or comparable detection limits for actinide isotopes with less time and effort.« less

High precision tungsten isotope analysis using MC-ICP-MS and application for terrestrial samples

NASA Astrophysics Data System (ADS)

Suzuki, K.; Takamasa, A.

2017-12-01

Tungsten has five isotopes (M = 180, 182, 183, 184, 186), and 182W isotope is a rediogenic isotope produced by b-decay of 182Hf. Its half life is short (8.9 m.y.), and 182W isotope has been investigated to understand the early Earth geochemical evolution. Both Hf and W are highly refractory elements. As Hf is a lithophile and W is a siderophile elements, 182Hf-182W system could give constraints on metal-silicate (core-mantle) differentiation such as especially early Earth system because of its larege fractionation betwenn core-mantle and short half life. Improvement of analytical techniques of W isotope analyses leads to findings of W isotope anomaly (mostly positive) in old komatiites (2.4 - 3.8 Ga) and young volcanic rocks (12 Ma Ontong Java Plateau and 6 Ma Baffin Bay). In our study, high-precision W isotope ratio measurement with MC-ICP-MS (Thermo co. Ltd., NEPTUNE PLUS). We have measured W standard solution (SRM 3163) and obtained the isotopic compositions with an precision of ± 5ppm. However, the standard solution, which separated by cation or anion exchange resin, has systematical 183W/184W drift to -5ppm. These phenomena was also reported by Willbold et al. (2011). Therefore, we used the standard solution for correction of isotopic fractionation of samples which was processed by the same method as that of the samples. We will present the data of terrestrial samples obtained by the technique dveloped in this study.

Determination of compound-specific Hg isotope ratios from transient signals using gas chromatography coupled to multicollector inductively coupled plasma mass spectrometry (MC-ICP/MS).

PubMed

Dzurko, Mark; Foucher, Delphine; Hintelmann, Holger

2009-01-01

MeHg and inorganic Hg compounds were measured in aqueous media for isotope ratio analysis using aqueous phase derivatization, followed by purge-and-trap preconcentration. Compound-specific isotope ratio measurements were performed by gas chromatography interfaced to MC-ICP/MS. Several methods of calculating isotope ratios were evaluated for their precision and accuracy and compared with conventional continuous flow cold vapor measurements. An apparent fractionation of Hg isotopes was observed during the GC elution process for all isotope pairs, which necessitated integration of signals prior to the isotope ratio calculation. A newly developed average peak ratio method yielded the most accurate isotope ratio in relation to values obtained by a continuous flow technique and the best reproducibility. Compound-specific isotope ratios obtained after GC separation were statistically not different from ratios measured by continuous flow cold vapor measurements. Typical external uncertainties were 0.16 per thousand RSD (n = 8) for the (202)Hg(/198)Hg ratio of MeHg and 0.18 per thousand RSD for the same ratio in inorganic Hg using the optimized operating conditions. Using a newly developed reference standard addition method, the isotopic composition of inorganic Hg and MeHg synthesized from this inorganic Hg was measured in the same run, obtaining a value of delta (202)Hg = -1.49 +/- 0.47 (2SD; n = 10). For optimum performance a minimum mass of 2 ng per Hg species should be introduced onto the column.

Multiple tag labeling method for DNA sequencing

DOEpatents

Mathies, Richard A.; Huang, Xiaohua C.; Quesada, Mark A.

1995-01-01

A DNA sequencing method described which uses single lane or channel electrophoresis. Sequencing fragments are separated in said lane and detected using a laser-excited, confocal fluorescence scanner. Each set of DNA sequencing fragments is separated in the same lane and then distinguished using a binary coding scheme employing only two different fluorescent labels. Also described is a method of using radio-isotope labels.

High Precision 142Nd/144Nd and 143Nd/144Nd Isotope Ratio Measurements in Rock Samples

NASA Astrophysics Data System (ADS)

Ali, A.; Srinivasan, G.

2009-05-01

The long-lived 147Sm-143Nd system with a half-life (T1/2) of 106 Gyr is generally used for geochronology. The short-lived 146Sm-142Nd system (T1/2= 103 Myr) is used as a geological tracer to track early (˜500 Ma) silicate differentiation [1] events in different planetary bodies. The isotope composition measurements by thermal ionization mass spectrometry (TIMS) require purification of Nd using chemical separation methods. This is important as an impure sample will give both a very poor ion yield and cause beam instability in the mass spectrometer, potentially resulting in a poor analysis [2]. The separation of Nd for 143Nd isotope measurement is, fairly straightforward because there is no isobaric interference of any other REE. While 142Nd isotope analysis needs chemically separated Nd fraction to be ˜100% Ce-free as latter is composed of a substantial amount of 142Ce isotope. A 4-steps technique, modified from Caro et al., [3], for the separation of Nd is established at the Cosmochemistry Laboratory of University of Toronto, Canada and applied to the measurement of Nd isotope ratios in geological reference sample BCR-2 (USGS, Columbia River basalt) using TIMS. Results of the isotopic ratios obtained for BCR-2 are in good agreement with published values [e.g., 4]. Analytical work on the samples discovered as the oldest rocks on Earth [5] from Nuvvuagittuq greenstone belt in Québec, Canada and various meteorites is in progress. An account of the procedures involved is briefly described here. All working solutions and acids were prepared using >18.2 MΩ.cm-1 H2O from a Milli-Q water system. Experiments were performed under Class 100 clean work bench with acid-cleaned apparatus and plastic-ware. The whole rock powders were weighed (20-30 mg) and dissolved in a mixture of HF and HNO3 using PFA vials and heated at 110°C. Further decomposition was done in Teflon bomb in the oven at 205°C. Later on contents of the Teflon bomb were transferred to vials and fluorides were removed with a mixtures of HClO4 and HCl. Finally the digested samples were dissolved in 4N HCl prior to the column chromatography. The separation of alkalis and REE was achieved with 2 ml BioRad column using AG®50W-X12 resin; following which the separation of Nd and Sm fractions was achieved using Ln-Spec resin in PFA column. Results: Triple filament geometry was used to measure Nd as a metal in multi-dynamic mode using Isoprobe-T TIMS. About 600x10-9 g of JNdi-1 standard [6] produced a 142Nd beam strength of ~5×10-11 A; 400 cycles constituted one measurement, where each cycle consisted of 4 sequences of 10 second counting time. A set of ˜10 measurements of JNdi-1 gave extremely accurate and precise ratios for 142/144, 143/144 and 145/144 with internal precision better than 4 ppm and an external precision of less than 7 ppm in all cases. The BCR-2 samples were loaded ˜200 ng (factor of 4 less than JNdi-1) and therefore their operating signal strength for 142Nd was ˜1×10-11 A. Based on our analyses we conclude that the internal precision for BCR-2 samples in the range of 8-9 ppm and their external precision is comparable to JNdi-1. References: [1] Caro et al, (2008) Nature 452, 336-339; [2] Míková & Denková, (2007) Geosciences 52, 221-226; [3] Caro et al, (2003) Nature 432, 428-432; [4] Raczek et al., (2003) Geostandards Newsletter 27, No.2, 173-179; [5] O'Neil et al, (2008) Science 321, 1828-1831; [6] Tanaka et al., (2000) Chem Geol, 168, 279-281.

Isotopic anomalies of H2 and C in the peat from the Tunguska meteorite impact area

NASA Astrophysics Data System (ADS)

Kolesnikov, E. M.

Core samples of peat collected at the site of the Tunguska meteorite impact were mixed with CuO and burned inside evacuated and sealed quartz ampules. As a result, the organic components of peat were transformed to H2O and CO2 which were then separated and analyzed using a mass spectrometer. Results show that layers located above the level dated by 1908 are characterized by lighter H2 isotopes and heavier C isotopes, compared with lower layers. These effects are ascribed to the conservation and gradual redistribution of cosmic matter (e.g., regular chondrites, achondrites, and C4-type carbon chondrites) in the upper peat layers.

Determination of uranium and thorium in materials associated with real time electronic solar neutrino detectors

NASA Astrophysics Data System (ADS)

Fassett, J. D.; Kelly, W. R.

1992-07-01

The application of isotope dilution thermal ionization mass spectrometry to the determination of both uranium and thorium in four different target materials used or proposed for electronic neutrino detectors is described. Isotope dilution analysis is done using highly enriched 233U and 230Th separated isotopes. Sensitivity of the technique is such that sub-picogram amounts of material are readily measured. The overall limit to measurement is caused by contamination of these elements during the measurement process. Uranium is more easily measured than thorium because both the instrumental sensitivity is higher and contamination is better controlled. The materials analyzed were light and heavy water, pseudocumene, and mineral oil.

Stable hydrogen and carbon isotope ratios of extractable hydrocarbons in the Murchison meteorite

NASA Technical Reports Server (NTRS)

Krishnamurthy, R. V.; Epstein, S.; Pizzarello, S.; Cronin, J. R.; Yuen, G. U.

1991-01-01

A fairly fool-proof method to ensure that the compounds isolated from meteorites are truly part of the meteorites and not an artifact introduced by exposure to the terrestrial environment, storage, or handling is presented. The stable carbon and hydrogen isotope ratios in several of the chemical compounds extracted from the Murchison meteorite were measured. The results obtained by studying the amino acids in this meteorite gave very unusual hydrogen and carbon isotope ratios. The technique was extended to the different classes of hydrocarbons and the hydrocarbons were isolated using a variety of separation techniques. The results and methods used in this investigation are described in this two page paper.

Reactive transport modeling of stable carbon isotope fractionation in a multi-phase multi-component system during carbon sequestration

DOE PAGES

Zhang, Shuo; DePaolo, Donald J.; Zheng, Liange; ...

2014-12-31

Carbon stable isotopes can be used in characterization and monitoring of CO 2 sequestration sites to track the migration of the CO 2 plume and identify leakage sources, and to evaluate the chemical reactions that take place in the CO 2-water-rock system. However, there are few tools available to incorporate stable isotope information into flow and transport codes used for CO 2 sequestration problems. We present a numerical tool for modeling the transport of stable carbon isotopes in multiphase reactive systems relevant to geologic carbon sequestration. The code is an extension of the reactive transport code TOUGHREACT. The transport modulemore » of TOUGHREACT was modified to include separate isotopic species of CO 2 gas and dissolved inorganic carbon (CO 2, CO 3 2-, HCO 3 -,…). Any process of transport or reaction influencing a given carbon species also influences its isotopic ratio. Isotopic fractionation is thus fully integrated within the dynamic system. The chemical module and database have been expanded to include isotopic exchange and fractionation between the carbon species in both gas and aqueous phases. The performance of the code is verified by modeling ideal systems and comparing with theoretical results. Efforts are also made to fit field data from the Pembina CO 2 injection project in Canada. We show that the exchange of carbon isotopes between dissolved and gaseous carbon species combined with fluid flow and transport, produce isotopic effects that are significantly different from simple two-component mixing. These effects are important for understanding the isotopic variations observed in field demonstrations.« less

Separation Potential for Multicomponent Mixtures: State-of-the Art of the Problem

NASA Astrophysics Data System (ADS)

Sulaberidze, G. A.; Borisevich, V. D.; Smirnov, A. Yu.

2017-03-01

Various approaches used in introducing a separation potential (value function) for multicomponent mixtures have been analyzed. It has been shown that all known potentials do not satisfy the Dirac-Peierls axioms for a binary mixture of uranium isotopes, which makes their practical application difficult. This is mainly due to the impossibility of constructing a "standard" cascade, whose role in the case of separation of binary mixtures is played by the ideal cascade. As a result, the only universal search method for optimal parameters of the separation cascade is their numerical optimization by the criterion of the minimum number of separation elements in it.

Hf and Nd Isotopic and REE Investigations of Magnetite in a Proterozoic IOCG system: Fingerprinting Sources and Timing of Mineralisation

NASA Astrophysics Data System (ADS)

Schaefer, B. F.

2016-12-01

The Stuart Shelf on the margin of the Gawler Craton, South Australia, contains numerous economic and sub-econmic IOCG mineralised systems, including the giant Olympic Dam Cu-Au-U deposit. Hematite and magnetite have played a critical in the genesis of all of these deposits, and increasingly it appears that magnetite has been in equilibrium with either the final mineralised assemblage or was critical in transporting metals during the ore forming event. 14 magnetites and one hematite from three separate styles of iron oxide mineralisation associated with the Prominent Hill Cu-Au deposit were selected for detailed analysis. The REE and isotopic separations were all conducted by low blank wet chemistry and isotopes determined by TIMS (Nd) and MC-ICPMS (Hf). Magnetites associated with skarn style mineralsiation proximal to the ore body are unformly depleted in REE, whereas hematite within the ore and magmatic magmatites and whole rock gabbros from the nearby 1590Ma White Hill Gabbro intrusion are all relatively LREE enriched and display a comparable range in REE. Significantly however, magnetite separates almost invariably display more evolved Hf isotopic signatures than the host lithologies adjacent the economic mineralisation (dacites and metasediments at Prominent Hill mine) implying that the magnetites were sourcing their REE inventory dominantly from the local crust rather than a mantle derived source. In contrast, the magmatic magnetites from the White Hill Complex display Nd and Hf isotopes which are slightly more primitive, recording a greater relative mantle component, however still requiring a significant crustal input. Significantly, the hematite which contains the Au mineralisation preserves ɛNd (1590) = -4.04 and ɛHf (1590) = -6.05 essentially identical to the magmatic magnetites and their host gabbros in the White Hill complex and the basalts and dacites of the host Gawler Range Volcanics (ɛNd (1590) = -7.10 - -3.72 and ɛHf (1590) = -7.69 - -1.89). Therefore it would appear that the mineralising event was driven by the intrusion of the White Hills Complex and proximal Gawler Range Volcanics.

EM reconstruction of dual isotope PET using staggered injections and prompt gamma positron emitters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andreyev, Andriy, E-mail: andriy.andreyev-1@philips.com; Sitek, Arkadiusz; Celler, Anna

2014-02-15

Purpose: The aim of dual isotope positron emission tomography (DIPET) is to create two separate images of two coinjected PET radiotracers. DIPET shortens the duration of the study, reduces patient discomfort, and produces perfectly coregistered images compared to the case when two radiotracers would be imaged independently (sequential PET studies). Reconstruction of data from such simultaneous acquisition of two PET radiotracers is difficult because positron decay of any isotope creates only 511 keV photons; therefore, the isotopes cannot be differentiated based on the detected energy. Methods: Recently, the authors have proposed a DIPET technique that uses a combination of radiotracermore » A which is a pure positron emitter (such as{sup 18}F or {sup 11}C) and radiotracer B in which positron decay is accompanied by the emission of a high-energy (HE) prompt gamma (such as {sup 38}K or {sup 60}Cu). Events that are detected as triple coincidences of HE gammas with the corresponding two 511 keV photons allow the authors to identify the lines-of-response (LORs) of isotope B. These LORs are used to separate the two intertwined distributions, using a dedicated image reconstruction algorithm. In this work the authors propose a new version of the DIPET EM-based reconstruction algorithm that allows the authors to include an additional, independent estimate of radiotracer A distribution which may be obtained if radioisotopes are administered using a staggered injections method. In this work the method is tested on simple simulations of static PET acquisitions. Results: The authors’ experiments performed using Monte-Carlo simulations with static acquisitions demonstrate that the combined method provides better results (crosstalk errors decrease by up to 50%) than the positron-gamma DIPET method or staggered injections alone. Conclusions: The authors demonstrate that the authors’ new EM algorithm which combines information from triple coincidences with prompt gammas and staggered injections improves the accuracy of DIPET reconstructions for static acquisitions so they reach almost the benchmark level calculated for perfectly separated tracers.« less

Chemical separation of Mo and W from terrestrial and extraterrestrial samples via anion exchange chromatography.

PubMed

Nagai, Yuichiro; Yokoyama, Tetsuya

2014-05-20

A new two-stage chemical separation method was established using an anion exchange resin, Eichrom 1 × 8, to separate Mo and W from four natural rock samples. First, the distribution coefficients of nine elements (Ti, Fe, Zn, Zr, Nb, Mo, Hf, Ta, and W) under various chemical conditions were determined using HCl, HNO3, and HF. On the basis of the obtained distribution coefficients, a new technique for the two-stage chemical separation of Mo and W, along with the group separation of Ti-Zr-Hf, was developed as follows: 0.4 M HCl-0.5 M HF (major elements), 9 M HCl-0.05 M HF (Ti-Zr-Hf), 9 M HCl-1 M HF (W), and 6 M HNO3-3 M HF (Mo). After the chemical procedure, Nb remaining in the W fraction was separated using 9 M HCl-3 M HF. On the other hand, Nb and Zn remaining in the Mo fraction were removed using 2 M HF and 6 M HCl-0.1 M HF. The performance of this technique was evaluated by separating these elements from two terrestrial and two extraterrestrial samples. The recovery yields for Mo, W, Zr, and Hf were nearly 100% for all of the examined samples. The total contents of the Zr, Hf, W, and Mo in the blanks used for the chemical separation procedure were 582, 9, 29, and 396 pg, respectively. Therefore, our new separation technique can be widely used in various fields of geochemistry, cosmochemistry, and environmental sciences and particularly for multi-isotope analysis of these elements from a single sample with significant internal isotope heterogeneities.

Precise and accurate isotope ratio measurements by ICP-MS.

PubMed

Becker, J S; Dietze, H J

2000-09-01

The precise and accurate determination of isotope ratios by inductively coupled plasma mass spectrometry (ICP-MS) and laser ablation ICP-MS (LA-ICP-MS) is important for quite different application fields (e.g. for isotope ratio measurements of stable isotopes in nature, especially for the investigation of isotope variation in nature or age dating, for determining isotope ratios of radiogenic elements in the nuclear industry, quality assurance of fuel material, for reprocessing plants, nuclear material accounting and radioactive waste control, for tracer experiments using stable isotopes or long-lived radionuclides in biological or medical studies). Thermal ionization mass spectrometry (TIMS), which used to be the dominant analytical technique for precise isotope ratio measurements, is being increasingly replaced for isotope ratio measurements by ICP-MS due to its excellent sensitivity, precision and good accuracy. Instrumental progress in ICP-MS was achieved by the introduction of the collision cell interface in order to dissociate many disturbing argon-based molecular ions, thermalize the ions and neutralize the disturbing argon ions of plasma gas (Ar+). The application of the collision cell in ICP-QMS results in a higher ion transmission, improved sensitivity and better precision of isotope ratio measurements compared to quadrupole ICP-MS without the collision cell [e.g., for 235U/238U approximately 1 (10 microg x L(-1) uranium) 0.07% relative standard deviation (RSD) vs. 0.2% RSD in short-term measurements (n = 5)]. A significant instrumental improvement for ICP-MS is the multicollector device (MC-ICP-MS) in order to obtain a better precision of isotope ratio measurements (with a precision of up to 0.002%, RSD). CE- and HPLC-ICP-MS are used for the separation of isobaric interferences of long-lived radionuclides and stable isotopes by determination of spallation nuclide abundances in an irradiated tantalum target.

Production of selenium-72 and arsenic-72

DOEpatents

Phillips, Dennis R.

1993-01-01

Methods for producing selenium-72, separating it from its daughter isotope arsenic-72, and generating multiple portions of a solution containing arsenic-72 from a reusable parent substance comprised of selenium-72.

Induced natural convection thermal cycling device

DOEpatents

Heung, Leung Kit [Aiken, SC

2002-08-13

A device for separating gases, especially isotopes, by thermal cycling of a separation column using a pressure vessel mounted vertically and having baffled sources for cold and heat. Coils at the top are cooled with a fluid such as liquid nitrogen. Coils at the bottom are either electrical resistance coils or a tubular heat exchange. The sources are shrouded with an insulated "top hat" and simultaneously opened and closed at the outlets to cool or heat the separation column. Alternatively, the sources for cold and heat are mounted separately outside the vessel and an external loop is provided for each circuit.

Techniques for the conversion to carbon dioxide of oxygen from dissolved sulfate in thermal waters

USGS Publications Warehouse

Nehring, N.L.; Bowen, P.A.; Truesdell, A.H.

1977-01-01

The fractionation of oxygen isotopes between dissolved sulfate ions and water provides a useful geothermometer for geothermal waters. The oxygen isotope composition of dissolved sulfate may also be used to indicate the source of the sulfate and processes of formation. The methods described here for separation, purification and reduction of sulfate to prepare carbon dioxide for mass spectrometric analysis are modifications of methods by Rafter (1967), Mizutani (1971), Sakai and Krouse (1971), and Mizutani and Rafter (1969). ?? 1976.

β-decay half-lives of new neutron-rich rare-earth isotopes 159Pm,162Sm, and 166Gd

NASA Astrophysics Data System (ADS)

Ichikawa, S.; Asai, M.; Tsukada, K.; Haba, H.; Nagame, Y.; Shibata, M.; Sakama, M.; Kojima, Y.

2005-06-01

The new neutron-rich rare-earth isotopes 159Pm, 162Sm, and 166Gd produced in the proton-induced fission of 238U were identified using the JAERI on-line isotope separator (JAERI-ISOL) coupled to a gas-jet transport system. The half-lives of 159Pm, 162Sm, and 166Gd were determined to be 1.5 ± 0.2, 2.4 ± 0.5, and 4.8 ± 1.0 s respectively. The partial decay scheme of 166Gd was constructed from γγ-coincidence data. A more accurate half-life value of 25.6 ± 2.2 s was obtained for the previously identified isotope 166Tb. The half-lives measured in the present study are in good agreement with the theoretical predictions calculated by the second generation of the gross theory with the atomic masses evaluated by Audi and Wapstra.

NanoSIMS Determination of Carbon and Oxygen Isotopic Compositions of Presolar Graphites from the Murchison Meteorite

NASA Technical Reports Server (NTRS)

Stadermann, F. J.; Croat, T. K.; Bernatowicz, T.

2004-01-01

Graphite from the Murchison density separate KFC1 (2.15 - 2.20 g/cu cm) has previously been studied by combined SEM/EDX and ion microprobe analysis. These studies found several distinct morphological types of graphites and C isotopic compositions that vary over more than 3 orders of magnitude, clearly establishing their presolar origin. Subsequent TEM measurements of a subset of these particles found abundant embedded crystals of metal (Zr, Mo, Ti, Ru) carbides which were incorporated during the growth of the graphites. A new TEM study of a large set of KFC1 graphites led to the discovery of another type of presolar material, Ru-Fe metal. Here we report results of the C and O isotopic measurements in the same graphite sections, which makes it possible for the first time to directly correlate isotopic and TEM data of KFC1 grains.

Development of a laser system of the laboratory AVLIS complex for producing isotopes and radionuclides

NASA Astrophysics Data System (ADS)

D'yachkov, A. B.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Panchenko, V. Ya.; Firsov, V. A.; Tsvetkov, G. O.

2018-01-01

The use of atomic vapour laser isotope separation (AVLIS) for solving a number of urgent problems (formation of 177Lu radionuclides for medical applications, 63Ni radionuclides for betavoltaic power supplies and 150Nd isotope for searching for neutrinoless double β decay and neutrino mass) is considered. An efficient three-step scheme of photoionisation of neodymium atoms through the 50474-cm-1 autoionising state with radiation wavelengths of the corresponding stages of λ1 = 6289.7 Å, λ2 = 5609.4 Å and λ3 = 5972.1 Å is developed. The average saturation intensity of the autoionising transition is ˜6 W cm-2, a value consistent with the characteristics of the previously developed photoionisation schemes for lutetium and nickel. A compact laser system for the technological AVLIS complex, designed to produce radionuclides and isotopes under laboratory conditions, is developed based on the experimental results.

Post-eruptive alteration of silicic ignimbrites and lavas, Gran Canaria, Canary Islands - Strontium, neodymium, lead, and oxygen isotopic evidence

NASA Technical Reports Server (NTRS)

Cousens, Brian L.; Spera, Frank J.; Dobson, Patrick F.

1993-01-01

The isotopic composition of lavas from oceanic islands provides important information about the composition and evolution of the earth's mantle. Isotopic analyses of Miocene comenditic, pantelleritic, and trachyphonolitic ignimbrites and lavas from the Canary islands were performed. Results provide evidence for posteruptive mobility of Rb and Sr during low temperature postemplacement interaction with circulating ground water. Calculated Sr isotope ratios define a magmatic trend in the stratigraph section. 87Sr/86Sr ratios in hydrated vitrophyte and devitrified matrix separates indicate significant posteruptive interaction with meteoric water starting soon after deposition. This process extends patchily through the entire pyroclastic flow and may be ongoing. 87Sr/86Sr ratios determined by whole rock analysis of silicic rocks from oceanic islands are suspect and should not be incorporated into mantle tracer studies. Anorthoclase phenocrysts are resistant to these processes and may produce useful data.

Isotope-Encoded Carboxyl Group Footprinting for Mass Spectrometry-Based Protein Conformational Studies

NASA Astrophysics Data System (ADS)

Zhang, Hao; Liu, Haijun; Blankenship, Robert E.; Gross, Michael L.

2016-01-01

We report an isotope-encoding method coupled with carboxyl-group footprinting to monitor protein conformational changes. The carboxyl groups of aspartic/glutamic acids and of the C-terminus of proteins can serve as reporters for protein conformational changes when labeled with glycine ethyl ester (GEE) mediated by carbodiimide. In the new development, isotope-encoded "heavy" and "light" GEE are used to label separately the two states of the orange carotenoid protein (OCP) from cyanobacteria. Two samples are mixed (1:1 ratio) and analyzed by a single LC-MS/MS experiment. The differences in labeling extent between the two states are represented by the ratio of the "heavy" and "light" peptides, providing information about protein conformational changes. Combining isotope-encoded MS quantitative analysis and carboxyl-group footprinting reduces the time of MS analysis and improves the sensitivity of GEE and other footprinting.

Isotope-encoded Carboxyl Group Footprinting for Mass Spectrometry-based Protein Conformational Studies

PubMed Central

Zhang, Hao; Liu, Haijun; Blankenship, Robert E.; Gross, Michael L.

2015-01-01

We report an isotope-encoding method coupled with carboxyl-group footprinting to monitor protein conformational changes. The carboxyl groups of aspartic/glutamic acids and of the C-terminus of proteins can serve as reporters for protein conformational changes when labeled with glycine ethyl ester (GEE) mediated by carbodiimide. In the new development, isotope-encoded “heavy” and “light” GEE are used to label separately the two states of the Orange Carotenoid Protein (OCP) from cyanobacteria. Two samples are mixed (1:1 ratio) and analyzed by a single LC-MS/MS experiment. The differences in labeling extent between the two states are represented by the ratio of the “heavy” and “light” peptides, providing information about protein conformational changes. Combining isotope-encoded MS quantitative analysis and carboxyl-group footprinting reduces the time of MS analysis and improves the sensitivity of GEE and other footprinting. PMID:26384685

Automatic measurements and computations for radiochemical analyses

USGS Publications Warehouse

Rosholt, J.N.; Dooley, J.R.

1960-01-01

In natural radioactive sources the most important radioactive daughter products useful for geochemical studies are protactinium-231, the alpha-emitting thorium isotopes, and the radium isotopes. To resolve the abundances of these thorium and radium isotopes by their characteristic decay and growth patterns, a large number of repeated alpha activity measurements on the two chemically separated elements were made over extended periods of time. Alpha scintillation counting with automatic measurements and sample changing is used to obtain the basic count data. Generation of the required theoretical decay and growth functions, varying with time, and the least squares solution of the overdetermined simultaneous count rate equations are done with a digital computer. Examples of the complex count rate equations which may be solved and results of a natural sample containing four ??-emitting isotopes of thorium are illustrated. These methods facilitate the determination of the radioactive sources on the large scale required for many geochemical investigations.

River Valley pluton, Ontario - A late-Archean/early-Proterozoic anorthositic intrusion in the Grenville Province

NASA Technical Reports Server (NTRS)

Ashwal, Lewis D.; Wooden, Joseph L.

1989-01-01

This paper presents Nd, Sr, and Pb isotopic data indicating a late-Archean/early-Proterozoic age for the River Valley anorthositic pluton of the southwestern Grenville Province of Sudbury, Ontario. Pb-Pb isotopic data on 10 whole-rock samples ranging in composition from anorthosite to gabbro yield an age of 2560 + or - 155 Ma. The River Valley pluton is thus the oldest anorthositic intrusive yet recognized within the Grenville Province. The Sm-Nd isotopic system records an age of 2377 + or - 68 Ma. High Pb-208/Pb-204 of deformed samples relative to igneous-textured rocks implies Th introduction and/or U loss during metamorphism in the River Valley area. Rb-Sr data from igneous-textured and deformed samples and from mineral separates give an age of 2185 + or - 105 Ma, indicating substantial disturbance of the Rb-Sr isotopic system.

The oxygen isotope composition of Almahata Sitta

NASA Astrophysics Data System (ADS)

Rumble, Douglas; Zolensky, Michael E.; Friedrich, Jon M.; Jenniskens, Peter; Shaddad, Muawia H.

2010-10-01

Eleven fragments of the meteorite Almahata Sitta (AHS) have been analyzed for oxygen isotopes. The fragments were separately collected as individual stones from the meteorite's linear strewn field in the Nubian Desert. Each of the fragments represents a sample of a different and distinct portion of asteroid 2008 TC3. Ten of the fragments span the same range of values of δ18O, δ17O, and Δ17O, and follow the same trend along the carbonaceous chondrite anhydrous minerals (CCAM) line as monomict and polymict members of the ureilite family of meteorites. The oxygen isotope composition of fragment #25 is consistent with its resemblance petrographically to an H5 ordinary chondrite. Our results demonstrate that a single small asteroidal parent body, asteroid 2008 TC3, only 4 m in length, encompassed the entire range of variation in oxygen isotope compositions measured for monomict and polymict ureilites.

Nuclear quantum shape-phase transitions in odd-mass systems

NASA Astrophysics Data System (ADS)

Quan, S.; Li, Z. P.; Vretenar, D.; Meng, J.

2018-03-01

Microscopic signatures of nuclear ground-state shape-phase transitions in odd-mass Eu isotopes are explored starting from excitation spectra and collective wave functions obtained by diagonalization of a core-quasiparticle coupling Hamiltonian based on energy density functionals. As functions of the physical control parameter—the number of nucleons—theoretical low-energy spectra, two-neutron separation energies, charge isotope shifts, spectroscopic quadrupole moments, and E 2 reduced transition matrix elements accurately reproduce available data and exhibit more-pronounced discontinuities at neutron number N =90 compared with the adjacent even-even Sm and Gd isotopes. The enhancement of the first-order quantum phase transition in odd-mass systems can be attributed to a shape polarization effect of the unpaired proton which, at the critical neutron number, starts predominantly coupling to Gd core nuclei that are characterized by larger quadrupole deformation and weaker proton pairing correlations compared with the corresponding Sm isotopes.

Observation of the isotope effect in sub-kelvin reactions

NASA Astrophysics Data System (ADS)

Lavert-Ofir, Etay; Shagam, Yuval; Henson, Alon B.; Gersten, Sasha; Kłos, Jacek; Żuchowski, Piotr S.; Narevicius, Julia; Narevicius, Edvardas

2014-04-01

Quantum phenomena in the translational motion of reactants, which are usually negligible at room temperature, can dominate reaction dynamics at low temperatures. In such cold conditions, even the weak centrifugal force is enough to create a potential barrier that keeps reactants separated. However, reactions may still proceed through tunnelling because, at low temperatures, wave-like properties become important. At certain de Broglie wavelengths, the colliding particles can become trapped in long-lived metastable scattering states, leading to sharp increases in the total reaction rate. Here, we show that these metastable states are responsible for a dramatic, order-of-magnitude-strong, quantum kinetic isotope effect by measuring the absolute Penning ionization reaction rates between hydrogen isotopologues and metastable helium down to 0.01 K. We demonstrate that measurements of a single isotope are insufficient to constrain ab initio calculations, making the kinetic isotope effect in the cold regime necessary to remove ambiguity among possible potential energy surfaces.

Isotope Labeling for Solution and Solid-State NMR Spectroscopy of Membrane Proteins

PubMed Central

Verardi, Raffaello; Traaseth, Nathaniel J.; Masterson, Larry R.; Vostrikov, Vitaly V.; Veglia, Gianluigi

2013-01-01

In this chapter, we summarize the isotopic labeling strategies used to obtain high-quality solution and solid-state NMR spectra of biological samples, with emphasis on integral membrane proteins (IMPs). While solution NMR is used to study IMPs under fast tumbling conditions, such as in the presence of detergent micelles or isotropic bicelles, solid-state NMR is used to study the structure and orientation of IMPs in lipid vesicles and bilayers. In spite of the tremendous progress in biomolecular NMR spectroscopy, the homogeneity and overall quality of the sample is still a substantial obstacle to overcome. Isotopic labeling is a major avenue to simplify overlapped spectra by either diluting the NMR active nuclei or allowing the resonances to be separated in multiple dimensions. In the following we will discuss isotopic labeling approaches that have been successfully used in the study of IMPs by solution and solid-state NMR spectroscopy. PMID:23076578

Isotope-Encoded Carboxyl Group Footprinting for Mass Spectrometry-Based Protein Conformational Studies

DOE PAGES

Zhang, Hao; Liu, Haijun; Blankenship, Robert E.; ...

2015-09-18

Here, we report an isotope-encoding method coupled with carboxyl-group footprinting to monitor protein conformational changes. The carboxyl groups of aspartic/glutamic acids and of the C-terminus of proteins can serve as reporters for protein conformational changes when labeled with glycine ethyl ester (GEE) mediated by carbodiimide. In the new development, isotope-encoded “heavy” and “light” GEE are used to label separately the two states of the orange carotenoid protein (OCP) from cyanobacteria. Two samples are mixed (1:1 ratio) and analyzed by a single LC-MS/MS experiment. The differences in labeling extent between the two states are represented by the ratio of the “heavy”more » and “light” peptides, providing information about protein conformational changes. Combining isotope-encoded MS quantitative analysis and carboxyl-group footprinting reduces the time of MS analysis and improves the sensitivity of GEE and other footprinting.« less

Investigating the Relationship Between Soil Water Mobility and Stable Isotope Composition with Implications for the Ecohydrologic Separation Hypothesis

NASA Astrophysics Data System (ADS)

Shuler, J.; McNamara, J. P.; Benner, S. G.; Kohn, M. J.; Evans, S.

2017-12-01

The ecohydrologic separation (ES) hypothesis states that streams and plants return different soil water compartments to the atmosphere and that these compartments bear distinct isotopic compositions that can be used to infer soil water mobility. Recent studies have found isotopic evidence for ES in a variety of ecosystems, though interpretations of these data vary. ES investigations frequently suffer from low sampling frequencies as well as incomplete or missing soil moisture and matric potential data to support assumptions of soil water mobility. We sampled bulk soil water every 2-3 weeks in the upper 1 m of a hillslope profile from May 2016 to July 2017 in a semi-arid watershed outside Boise, ID. Twig samples of three plant species were also collected concurrently. Plant and soil water samples extracted via cryogenic vacuum distillation were analyzed for δ2H and δ18O composition. Soil moisture and soil matric potential sensors were installed at five and four depths in the profile, respectively. Shallow bulk soil water was progressively enriched in both isotopes over the growing season and plotted along a soil evaporation line in a plot of δ2H versus δ18O. Plant water during the growing season plotted below both the Local Meteoric Water Line and soil evaporation line. Plant water isotopic composition could not be traced to any source sampled in this study. Additionally, soil moisture and matric potential data revealed that soils were well-drained and that mobile soil water was unavailable throughout most of the growing season at the depths sampled. Soil water isotopic composition alone failed to predict mobility as observed in soil moisture and matric potential data. These results underscore the need for standard hydrologic definitions for the mobile and immobile compartments of soil water in future studies of the ES hypothesis and ecohydrologic processes in general.

Determination of ultra-low level plutonium isotopes (239Pu, 240Pu) in environmental samples with high uranium.

PubMed

Xing, Shan; Zhang, Weichao; Qiao, Jixin; Hou, Xiaolin

2018-09-01

In order to measure trace plutonium and its isotopes ratio ( 240 Pu/ 239 Pu) in environmental samples with a high uranium, an analytical method was developed using radiochemical separation for separation of plutonium from matrix and interfering elements including most of uranium and ICP-MS for measurement of plutonium isotopes. A novel measurement method was established for extensively removing the isobaric interference from uranium ( 238 U 1 H and 238 UH 2 + ) and tailing of 238 U, but significantly improving the measurement sensitivity of plutonium isotopes by employing NH 3 /He as collision/reaction cell gases and MS/MS system in the triple quadrupole ICP-MS instrument. The results show that removal efficiency of uranium interference was improved by more than 15 times, and the sensitivity of plutonium isotopes was increased by a factor of more than 3 compared to the conventional ICP-MS. The mechanism on the effective suppress of 238 U interference for 239 Pu measurement using NH 3 -He reaction gases was explored to be the formation of UNH + and UNH 2 + in the reactions of UH + and U + with NH 3 , while no reaction between NH 3 and Pu + . The detection limits of this method were estimated to be 0.55 fg mL -1 for 239 Pu, 0.09 fg mL -1 for 240 Pu. The analytical precision and accuracy of the method for Pu isotopes concentration and 240 Pu/ 239 Pu atomic ratio were evaluated by analysis of sediment reference materials (IAEA-385 and IAEA-412) with different levels of plutonium and uranium. The developed method were successfully applied to determine 239 Pu and 240 Pu concentrations and 240 Pu/ 239 Pu atomic ratios in soil samples collected in coastal areas of eastern China. Copyright © 2018 Elsevier B.V. All rights reserved.

Paloma: In-situ Measurement of The Elemental and Isotopic Composition of The Mars Atmosphere

NASA Astrophysics Data System (ADS)

Chassefiere, E.; Jambon, A.; Berthelier, J.-J.; Correia, J.-J.; Covinhes, J.; Goulpeau, G.; Leblanc, F.; Malique, Ch.; Sarda, P.; Schaetzel, P.; Sabroux, J.-C.; Ferry, C.; Richon, P.; Pineau, J.-F.; Desjean, M.-C.

The PALOMA instrument, presently under study in the frame of the NASA/CNES Mars exploration program, is devoted to the accurate measurement of isotopic and el- emental ratios in Mars atmosphere. It consists of a mass spectrometer coupled with a gas preparation line for separation of reactive and noble gas species, and noble gas species (and reactive gases) from each other, by chemical and cryogenic trapping, and possibly permeation techniques. This instrument, ranked among the most important four types of measurement recommended by the US Committee on Planetary and Lu- nar Exploration (COMPLEX), will be proposed as a part of the payload of the 07 NASA smart landers. The general objectives of PALOMA are to provide instanta- neous and time-varying patterns of noble gas isotopic spectra, and stable isotopes. Such measurements will allow to improve our general understanding of volatile cy- cles on Mars, and to better decipher the history of the atmosphere and climate. Past escape processes, exchanges between solid planet and atmosphere, post-accretional addition of volatil-rich matter from comets, are expected to have imprinted specific isotopic signatures. Although these signatures are strongly interlocked, a compara- tive Earth-Mars approach may allow to discriminate between them, and therefore to reconstruct the history of Martian volatiles. The evolution of atmospheric mass and composition may have had a major impact on climate evolution, e.g. through massive escape of carbon dioxide and water. In addition, precise measurements of isotopes in the present Mars atmosphere are the most promising way on the short term to confirm that SNC meteorites are from Martian origin. PALOMA also includes a small separate device for measuring ambient natural radioactivity, which might provide information about the presence of a near subsurface permafrost, possible residual volcanic activity, vertical mixing rate in the boundary layer.

Residency of rhenium and osmium in a heavy crude oil

NASA Astrophysics Data System (ADS)

DiMarzio, Jenna M.; Georgiev, Svetoslav V.; Stein, Holly J.; Hannah, Judith L.

2018-01-01

Rhenium-osmium (Re-Os) isotope geochemistry is an emerging tool for the study of oil formation and migration processes, and a new technology for petroleum exploration. Little is known, however, about the residency of Re and Os within asphaltene and maltene sub-fractions of crude oil. This information is crucial for understanding the 187Re-187Os radiometric clock held in petroleum systems and for interpreting geochronology for key processes such as oil formation, migration, and biodegradation. In this study, a heavy crude oil was separated into soluble (maltene, MALT) and insoluble (asphaltene, ASPH) fractions using n-heptane as the asphaltene-precipitating agent. The asphaltenes were separated sequentially into sub-fractions using two different solvent pairs (heptane-dichloromethane and acetone-toluene), and the bulk maltenes were separated into saturate, aromatic, and resin (SAR) fractions using open column chromatography. Each asphaltene and maltene sub-fraction was analyzed for Re and Os. The asphaltene sub-fractions and the bulk ASPH, MALT, and crude oil were analyzed for a suite of trace metals by ICP-MS. Our results show that Re and Os concentrations co-vary between the asphaltene sub-fractions, and that both elements are found mostly in the more polar and aromatic sub-fractions. Significant Re and Os are also present in the aromatic and resin fractions of the maltenes. However, each asphaltene and maltene sub-fraction has a distinct isotopic composition, and sub-fractions are not isochronous. This suggests that asphaltene sub-fractionation separates Re-Os complexes to the point where the isotopic integrity of the geochronometer is compromised. The mobility of individual Re and Os isotopes and the decoupling possibilities between radiogenic 187Os produced from 187Re remain elusive, but their recognition in this study is a critical first step. Re and Os correlate strongly with Mo and Cd in the asphaltene sub-fractions, suggesting that these metals occupy similar sites. Re-Os and Ni-V budgets also show some similarities, indicating that at least some Re (and possibly Os) could be present in metalloporphyrin form. We conclude that progressive asphaltene precipitation during migration and mixing of oils can change the isotopic ratios of the resultant oil. A sense of process is key to interpretation of Re-Os data for tar mats and live oils, whether isochronous or scattered datasets result. Optimally, by combining data from source rocks, oils, and asphaltenes generated along the migration pathway, we can construct temporal histories for whole petroleum systems.

Using isotopes of dissolved inorganic carbon species and water to separate sources of recharge in a cave spring, northwestern Arkansas, USA Blowing Spring Cave

USGS Publications Warehouse

Knierim, Katherine J.; Pollock, Erik; Hays, Phillip D.

2013-01-01

Blowing Spring Cave in northwestern Arkansas is representative of cave systems in the karst of the Ozark Plateaus, and stable isotopes of water (δ18O and δ2H) and inorganic carbon (δ13C) were used to quantify soil-water, bedrock-matrix water, and precipitation contributions to cave-spring flow during storm events to understand controls on cave water quality. Water samples from recharge-zone soils and the cave were collected from March to May 2012 to implement a multicomponent hydrograph separation approach using δ18O and δ2H of water and dissolved inorganic carbon (δ13C–DIC). During baseflow, median δ2H and δ18O compositions were –41.6‰ and –6.2‰ for soil water and were –37.2‰ and –5.9‰ for cave water, respectively. Median DIC concentrations for soil and cave waters were 1.8 mg/L and 25.0 mg/L, respectively, and median δ13C–DIC compositions were –19.9‰ and –14.3‰, respectively. During a March storm event, 12.2 cm of precipitation fell over 82 h and discharge increased from 0.01 to 0.59 m3/s. The isotopic composition of precipitation varied throughout the storm event because of rainout, a change of 50‰ and 10‰ for δ2H and δ18O was observed, respectively. Although, at the spring, δ2H and δ18O only changed by approximately 3‰ and 1‰, respectively. The isotopic compositions of precipitation and pre-event (i.e., soil and bedrock matrix) water were isotopically similar and the two-component hydrograph separation was inaccurate, either overestimating (>100%) or underestimating (<0%) the precipitation contribution to the spring. During the storm event, spring DIC and δ13C–DIC decreased to a minimum of 8.6 mg/L and –16.2‰, respectively. If the contribution from precipitation was assumed to be zero, soil water was found to contribute between 23 to 72% of the total volume of discharge. Although the assumption of negligible contributions from precipitation is unrealistic, especially in karst systems where rapid flow through conduits occurs, the hydrograph separation using inorganic carbon highlights the importance of considering vadose-zone soil water when analyzing storm chemohydrographs.

Production of platinum radioisotopes at Brookhaven Linac Isotope Producer (BLIP)

DOE PAGES

Smith, Suzanne V.; Mccutchan, Elizabeth; Gurdal, Gulhan; ...

2017-09-13

The accelerator production of platinum isotopes was investigated at the Brookhaven Linac Isotope Producer (BLIP). In this paper high purity natural platinum foils were irradiated at 53.2, 65.7, 105.2, 151.9, 162.9 and 173.3 MeV. The irradiated foils were digested in aqua regia and then converted to their hydrochloride salt with concentrated hydrochloric acid before analyzing by gamma spectrometry periodically for at least 10 days post end of bombardment. A wide range of platinum (Pt), gold (Au) and iridiu m (Ir) isotopes were identified. Effective cross sections at BLIP for Pt-188, Pt-189, Pt-191 and Pt-195m were compared to literature and theoreticalmore » cross sections determined using Empire-3.2. The majority of the effective cross sections (<70 MeV) confirm those reported in the literature. While the absolute values of the theoretical cross sections were up to a factor of 3 lower, Empire 3.2 modeled thresholds and maxima correlated well with experimental values. Preliminary evaluation into a rapid separation of Pt isotopes from high levels of Ir and Au isotopes proved to be a promising approach for large scale production. In conclusion, this study demonstrated that with the use of isotopically enriched target material accelerator production of selected platinum isotopes is feasible over a wide proton energy range.« less

Heterodyne laser spectroscopy system

DOEpatents

Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

1990-01-01

A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency, and provides spectral analysis of a laser beam.

Production of selenium-72 and arsenic-72

DOEpatents

Phillips, D.R.

1993-04-20

Methods are described for producing selenium-72, separating it from its daughter isotope arsenic-72, and generating multiple portions of a solution containing arsenic-72 from a reusable parent substance comprised of selenium-72.

Study of the Photon Strength Functions for Gadolinium Isotopes with the DANCE Array

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dashdorj, D.; Mitchell, G. E.; Baramsai, B.

2009-03-10

The gadolinium isotopes are interesting for reactor applications as well as for medicine and astrophysics. The gadolinium isotopes have some of the largest neutron capture cross sections. As a consequence they are used in the control rod in reactor fuel assembly. From the basic science point of view, there are seven stable isotopes of gadolinium with varying degrees of deformation. Therefore they provide a good testing ground for the study of deformation dependent structure such as the scissors mode. Decay gamma rays following neutron capture on Gd isotopes are detected by the DANCE array, which is located at flight pathmore » 14 at the Lujan Neutron Scattering Center at Los Alamos National Laboratory. The high segmentation and close packing of the detector array enable gamma-ray multiplicity measurements. The calorimetric properties of the DANCE array coupled with the neutron time-of-flight technique enables one to gate on a specific resonance of a specific isotope in the time-of-flight spectrum and obtain the summed energy spectrum for that isotope. The singles gamma-ray spectrum for each multiplicity can be separated by their DANCE cluster multiplicity. Various photon strength function models are used for comparison with experimentally measured DANCE data and provide insight for understanding the statistical decay properties of deformed nuclei.« less

Quantifying Uranium Isotope Ratios Using Resonance Ionization Mass Spectrometry: The Influence of Laser Parameters on Relative Ionization Probability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Isselhardt, Brett H.

2011-09-01

Resonance Ionization Mass Spectrometry (RIMS) has been developed as a method to measure relative uranium isotope abundances. In this approach, RIMS is used as an element-selective ionization process to provide a distinction between uranium atoms and potential isobars without the aid of chemical purification and separation. We explore the laser parameters critical to the ionization process and their effects on the measured isotope ratio. Specifically, the use of broad bandwidth lasers with automated feedback control of wavelength was applied to the measurement of 235U/ 238U ratios to decrease laser-induced isotopic fractionation. By broadening the bandwidth of the first laser inmore » a 3-color, 3-photon ionization process from a bandwidth of 1.8 GHz to about 10 GHz, the variation in sequential relative isotope abundance measurements decreased from >10% to less than 0.5%. This procedure was demonstrated for the direct interrogation of uranium oxide targets with essentially no sample preparation. A rate equation model for predicting the relative ionization probability has been developed to study the effect of variation in laser parameters on the measured isotope ratio. This work demonstrates that RIMS can be used for the robust measurement of uranium isotope ratios.« less

Boundary-value problem for a counterrotating electrical discharge in an axial magnetic field. [plasma centrifuge for isotope separation

NASA Technical Reports Server (NTRS)

Hong, S. H.; Wilhelm, H. E.

1978-01-01

An electrical discharge between two ring electrodes embedded in the mantle of a cylindrical chamber is considered, in which the plasma in the anode and cathode regions rotates in opposite directions under the influence of an external axial magnetic field. The associated boundary-value problem for the coupled partial differential equations describing the azimuthal velocity and radial current-density fields is solved in closed form. The velocity, current density, induced magnetic induction, and electric fields are presented for typical Hartmann numbers, magnetic Reynolds numbers, and geometry parameters. The discharge is shown to produce anodic and cathodic plasma sections rotating at speeds of the order 1,000,000 cm/sec for conventional magnetic field intensities. Possible application of the magnetoactive discharge as a plasma centrifuge for isotope separation is discussed.

U-Th-Pb isotopic systematics of lunar norite 78235

NASA Technical Reports Server (NTRS)

Premo, W. R.; Tatsumoto, M.

1991-01-01

A pristine high-Mg noritic cumulate thought to be relict deep-seated lunar crust is studied with an eye to obtaining evidence of initial Pb isotopic composition and U/Pb ratios of early lunar magma sources and possibly of a primary magma ocean. A leaching procedure was conducted on polymineralic separates to assure the removal of secondary Pb components. The Pb from leached separates do not form a linear trend on the Pb-Pb diagram, indicating open-system behavior either from mixtures of Pb or postcrystallization disturbances. Calculated initial Pb compositions and corresponding U-238/Pb-204 (mu) values are presented, with the assumption of reasonably precise radiometric ages from the literature for norite 78236. The results obtained support the contention that high-Mg suite rocks are coeval with the ferroan anorthosites, both being produced during the earliest stages of lunar evolution.

First calibration measurements of an FTIR absorption spectroscopy system for liquid hydrogen isotopologues for the isotope separation system of fusion power plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Groessle, R.; Beck, A.; Bornschein, B.

2015-03-15

Fusion facilities like ITER and DEMO will circulate huge amounts of deuterium and tritium in their fuel cycle with an estimated throughput of kg per hour. One important capability of these fuel cycles is to separate the hydrogen isotopologues (H{sub 2}, D{sub 2}, T{sub 2}, HD, HT, DT). For this purpose the Isotope Separation System (ISS), using cryogenic distillation, as part of the Tritium Enrichment Test Assembly (TRENTA) is under development at Tritium Laboratory Karlsruhe. Fourier transform infrared absorption spectroscopy (FTIR) has been selected to prove its capability for online monitoring of the tritium concentration in the liquid phase atmore » the bottom of the distillation column of the ISS. The actual research-development work is focusing on the calibration of such a system. Two major issues are the identification of appropriate absorption lines and their dependence on the isotopic concentrations and composition. For this purpose the Tritium Absorption IR spectroscopy experiment has been set up as an extension of TRENTA. For calibration a Raman spectroscopy system is used. First measurements, with equilibrated mixtures of H{sub 2}, D{sub 2} and HD demonstrate that FTIR can be used for quantitative analysis of liquid hydro-gen isotopologues and reveal a nonlinear dependence of the integrated absorbance from the D{sub 2} concentration in the second vibrational branch of D{sub 2} FTIR spectra. (authors)« less

Stable isotopic indicators of nitrous oxide and methane sources in Los Angeles, California

NASA Astrophysics Data System (ADS)

Townsend-Small, A.; Pataki, D.; Tyler, S.; Trumbore, S.

2008-12-01

As urbanization increasingly encroaches upon agricultural landscapes, there are greater potential sources of greenhouse gases and other atmospheric contaminants. Measurements of the isotopic composition of trace gases have the potential to distinguish between pollutant sources and quantify the proportional contribution of agricultural activities to the total atmospheric pool. In this study, we are measuring the isotopic composition of greenhouse gases N2O and CH4 emitted from cropland, animal feeding operations, and urban activities in the South Coast Air Basin in southern California. The ultimate goal of our project is to utilize atmospheric measurements of the isotopic composition of N2O and CH4 combined with studies of source signatures to determine the proportional contributions of cropland, animal operations, and urban sources of greenhouse gases to the atmosphere. Measurements of the δ13C of methane show excellent separation between urban sources, such as vehicle emissions, power plants, oil refineries, landfills, and sewage treatment plants and agricultural sources like cows, biogas, and cattle feedlots. For nitrous oxide, soil N2O sources showed good separation from wastewater treatment facilities using δ15N and δ18O. Within soil N2O sources, the isotopic composition of N2O from cropland soils was similar to N2O emissions from urban turfgrass. These data indicate that nitrification may be as important a source of N2O as denitrification in urban soils. We are also measuring N2O fluxes from soils and from sewage treatment processes, and preliminary data indicate that urban N2O fluxes are higher than initially assumed by managers and regulatory agencies.

The value and throughput of rest Thallium-201/stress Technetium -99m sestamibi dual-isotope myocardial SPECT.

PubMed

Okudan, Berna; Smitherman, Thomas C

2004-06-01

Myocardial perfusion scintigraphy is an established method in cardiology for the diagnosis and evaluation of coronary artery disease (CAD). Thallium-201 and Tc-99m sestamibi myocardial perfusion imaging has been widely accepted as non-invasive diagnostic procedure for detection of CAD, risk stratification and myocardial viability assessment. But, standard Tl-201 redistribution and same day or 2-day rest/stress Tc-99m sestamibi protocols are time-consuming. Hence, the dual isotope rest thallium-201/stress technetium-99m sestamibi gated single-photon emission tomography protocol has gained increasing popularity for these applications. Combining the use of thallium-201 with technetium-99m agents permits optimal image resolution and simultaneous assessment of viability. Dual-isotope imaging may be separate or simultaneous acquisition set-up. The more rapid completion of these studies is appreciated as an advantage by patients, technologists, interpreting and referring physicians, nurses and hospital management. Simultaneous imaging has the potential advantages of precise pixel registration and artifacts, if present, are identical in both thallium and sestamibi, and require only one set of imaging. Also, there are some disadvantages of spillover of activity from the Tc-99m to the Tl-201 window. Fortunately, despite this problem it can be overcome. Separate acquisition dual isotope also has some disadvantages. Difference in defect resolution in attenuation and scatter between T-201 and Tc-99m sestamibi potentially results in interpretation problems. But, studies about cost-effectiveness of dual isotope imaging showed that some selective elimination of the rest studies may decrease the cost of the nuclear procedures and should be considered in the current care health system.

Variation in nitrate isotopic signatures in sewage for source apportionment with urbanization: a case study in Beijing, China.

PubMed

Xian, Chaofan; Ouyang, Zhiyun; Li, Yanmin; Xiao, Yang; Ren, Yufen

2016-11-01

Nitrate (NO 3 - ) pollution is a severe problem in urban aquatic systems especially within megacity undergoing rapid urbanization, and mostly, sewage is supposed as the prevailing NO 3 - source. A dual isotope approach (δ 15 N-NO 3 - and δ 18 O-NO 3 - ) was applied to explore the variation in NO 3 - isotopic signatures in sewage processed by wastewater treatment plants (WWTPs) in Beijing from 2014 to 2015. We found that the raw and treated sewage owned the different NO 3 - isotopic signatures, including δ 15 N from 1.1 to 24.7 ‰ and δ 18 O from 1.6 to 22.8 ‰ in raw sewage, as well as δ 15 N from 6.1 to 22.8 ‰ and δ 18 O from 1.6 to 13.2 ‰ in treated effluents. The WWTP processing would result in the enrichment of NO 3 - isotopic compositions in discharged effluents with NO 3 - concentrations increasing. Besides, advanced sewage treatment technology with more pollutant N reduction may raise the heavier NO 3 - isotopic compositions further. The NO 3 - isotope value ranges of urban sewage and manure should be separated, and the seasonal and tighter NO 3 - isotope value ranges are supposed to improve the accuracy of source apportionment. The NO 3 - isotope value ranges conducted in this study might provide useful information for tracing NO 3 - sources towards the implementation of efficient water pollution control in Beijing.

RAPID DETERMINATION OF ACTINIDES IN URINE BY INDUCTIVELY-COUPLED PLASMA MASS SPECTROMETRY AND ALPHA SPECTROMETRY: A HYBRID APPROACH

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maxwell, S.; Jones, V.

2009-05-27

A new rapid separation method that allows separation and preconcentration of actinides in urine samples was developed for the measurement of longer lived actinides by inductively coupled plasma mass spectrometry (ICP-MS) and short-lived actinides by alpha spectrometry; a hybrid approach. This method uses stacked extraction chromatography cartridges and vacuum box technology to facilitate rapid separations. Preconcentration, if required, is performed using a streamlined calcium phosphate precipitation. Similar technology has been applied to separate actinides prior to measurement by alpha spectrometry, but this new method has been developed with elution reagents now compatible with ICP-MS as well. Purified solutions are splitmore » between ICP-MS and alpha spectrometry so that long- and short-lived actinide isotopes can be measured successfully. The method allows for simultaneous extraction of 24 samples (including QC samples) in less than 3 h. Simultaneous sample preparation can offer significant time savings over sequential sample preparation. For example, sequential sample preparation of 24 samples taking just 15 min each requires 6 h to complete. The simplicity and speed of this new method makes it attractive for radiological emergency response. If preconcentration is applied, the method is applicable to larger sample aliquots for occupational exposures as well. The chemical recoveries are typically greater than 90%, in contrast to other reported methods using flow injection separation techniques for urine samples where plutonium yields were 70-80%. This method allows measurement of both long-lived and short-lived actinide isotopes. 239Pu, 242Pu, 237Np, 243Am, 234U, 235U and 238U were measured by ICP-MS, while 236Pu, 238Pu, 239Pu, 241Am, 243Am and 244Cm were measured by alpha spectrometry. The method can also be adapted so that the separation of uranium isotopes for assay is not required, if uranium assay by direct dilution of the urine sample is preferred instead. Multiple vacuum box locations may be set-up to supply several ICP-MS units with purified sample fractions such that a high sample throughput may be achieved, while still allowing for rapid measurement of short-lived actinides by alpha spectrometry.« less

Evolution of the upper mantle beneath the southern Baikal rift zone: an Sr-Nd isotope study of xenoliths from the Bartoy volcanoes

NASA Astrophysics Data System (ADS)

Ionov, D. A.; Kramm, U.; Stosch, H.-G.

1992-06-01

Anhydrous and amphibole-bearing peridotite xenoliths occur in roughly equal quantitites in the Bartoy volcanic field about 100 km south of the southern tip of Lake Baikal in Siberia (Russia). Whole-rock samples and pure mineral separates from nine xenoliths have been analyzed for Sr and Nd isotopes in order to characterize the upper mantle beneath the southern Baikal rift zone. In an Sr-Nd isotope diagram both dry and hydrous xenoliths from Bartoy plot at the junction between the fields of MORB and ocean island basalts. This contrasts with data available on two other localities around Lake Baikal (Tariat and Vitim) where peridotites typically have Sr-Nd isotope compositions indicative of strong long-term depletion in incompatible elements. Our data indicate significant chemical and isotopic heterogeneity in the mantle beneath Bartoy that may be attributed to its position close to an ancient suture zone separating the Siberian Platform from the Mongol-Okhotsk mobile belt and occupied now by the Baikal rift. Two peridotites have clinopyroxenes depleted in light rare earth elements (LREE) with Sr and Nd model ages of about 2 Ga and seem to retain the trace element and isotopic signatures of old depleted lithospheric mantle, while all other xenoliths show different degrees of LREE-enrichment. Amphiboles and clinopyroxenes in the hydrous peridotites are in Sr-Nd isotopic disequilibrium. If this reflects in situ decay of 147Sm and 87Rb rather than heterogeneities produced by recent metasomatic formation of amphiboles then 300 400 Ma have passed since the minerals were last in equilibrium. This age range then indicates an old enrichment episode or repeated events during the Paleozoic in the lithospheric mantle initially depleted maybe ˜2 Ga ago. The Bartoy hydrous and enriched dry peridotites, therefore, are unlikely to represent fragments of a young asthenospheric bulge which, according to seismic reflection studies, reached the Moho at the axis of the Baikal rift zone a few Ma ago. By contrast, hydrous veins in peridotites may be associated with rift formation processes.

Neutron Capture Experiments on Unstable Nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schwantes, Jon M.; Sudowe, Ralf; Folden, Charles M., III

2005-01-15

The overall objective of this project is the measurement of neutron capture cross sections of importance to stewardship science and astrophysical modeling of nucleosynthesis, while at the same time helping to train the next generation of scientists with expertise relevant to U.S. national nuclear security missions and to stewardship science. A primary objective of this project is to study neutron capture cross sections for various stable and unstable isotopes that will contribute to the Science Based Stockpile Stewardship (SBSS) program by providing improved data for modeling and interpretation of nuclear device performance. Much of the information obtained will also bemore » important in astrophysical modeling of nucleosynthesis. Measurements of these neutron capture cross sections are being conducted in collaboration with researchers at the Los Alamos Neutron Science Center (LANSCE) facility using the unique Detector for Advanced Neutron Capture Experiments (DANCE). In our early discussions with the DANCE group, decisions were made on the first cross sections to be measured and how our expertise in target preparation, radiochemical separations chemistry, and data analysis could best be applied. The initial emphasis of the project was on preparing suitable targets of both natural and separated stable europium isotopes in preparation for the ultimate goal of preparing a sufficiently large target of radioactive 155Eu (t1/2 = 4.7 years) and other radioactive and stable species for neutron cross-section measurements at DANCE. Our Annual Report, ''Neutron Capture Experiments on Unstable Nuclei'' by J. M. Schwantes, R. Sudowe, C. M. Folden III, H. Nitsche, and D. C. Hoffman, submitted to NNSA in December 2003, gives details about the initial considerations and scope of the project. During the current reporting period, electroplated targets of natural Eu together with valuable, stable, and isotopically pure 151Eu and 153Eu, and isotopically separated 154Sm were measured for the first time at the DANCE facility in early 2004. The Eu targets, suitable blanks, Be backing foils, and standards had been sent to the DANCE group in early fall 2003. Some preliminary data analysis was performed and more sophisticated analysis has begun. We developed plans for a suitable computer system for data analysis within our group at Berkeley and had meetings with counterparts at Lawrence Livermore National Laboratory (LLNL) and LANL concerning analysis of these data. Our major emphasis in 2004 has been to develop the separations and processes ultimately required to prepare radioactive targets of 4.7-year 155Eu. Efforts continued to devise an optimum multiprocess procedure suitable for use in separating radioactive 155Eu already produced by irradiation of stable 154Sm in a high neutron flux reactor at the Institut Laue-Langevin in France and shipped to LANL (the 22-min 155Sm neutron-capture product decays to 155Eu). This separation is extremely demanding because the highly radioactive 155Eu must be isolated from about 20 times as much mass of samarium before a target can be prepared for DANCE measurements. After all the procedures have been fully tested the radioactive 155Eu will be separated. The same electroplating methods already used successfully to prepare stable Eu isotope targets will be used to prepare the 155Eu target for DANCE. Discussions were held with LANL radiochemists in the Chemistry (C) Division about appropriate facilities at LANL for conducting the full-scale separation and purification of the radioactive targets. Three more multiprocess separations were developed that generated less chemical and radioactive waste, but they must still be adapted for processing hundred-milligram quantities. Until these separations can be successfully implemented at this scale, standard HPLC procedures will be used for separating and preparing radioactive 155Eu, 2.6-year 147Pm, and 1.9-year 171Tm target materials. Future directions beyond the preparation of radioactive lanthanide targets include closer collaboration with both LLNL and LANL to prepare actinide targets such as plutonium, americium, and curium. Also, the applicability of established and novel techniques will be evaluated for rapid separations of Am and Cm required in the irradiation of 241Am. Lastly, we will conduct a series of experiments aimed at enhancing current methods used to electrodeposit lanthanide and actinide targets on thin Ti and Be backings.« less

Origin of Xylitol in Chewing Gum: A Compound-Specific Isotope Technique for the Differentiation of Corn- and Wood-Based Xylitol by LC-IRMS.

PubMed

Köster, Daniel; Wolbert, Jens-Benjamin; Schulte, Marcel S; Jochmann, Maik A; Schmidt, Torsten C

2018-02-28

The sugar replacement compound xylitol has gained increasing attention because of its use in many commercial food products, dental-hygiene articles, and pharmaceuticals. It can be classified by the origin of the raw material used for its production. The traditional "birch xylitol" is considered a premium product, in contrast to xylitol produced from agriculture byproducts such as corn husks or sugar-cane straw. Bulk stable-isotope analysis (BSIA) and compound-specific stable-isotope analysis (CSIA) by liquid-chromatography isotope-ratio mass spectrometry (LC-IRMS) of chewing-gum extracts were used to determine the δ 13 C isotope signatures for xylitol. These were applied to elucidate the original plant type the xylitol was produced from on the basis of differences in isotope-fractionation processes of photosynthetic CO 2 fixation. For the LC-IRMS analysis, an organic-solvent-free extraction protocol and HPLC method for the separation of xylitol from different artificial sweeteners and sugar-replacement compounds was successfully developed and applied to the analysis of 21 samples of chewing gum, from which 18 could be clearly related to the raw-material plant class.

Isotopic and Chemical Evidence for Primitive Aqueous Alteration in the Tagish Lake Meteorite

NASA Astrophysics Data System (ADS)

Sakuma, Keisuke; Hidaka, Hiroshi; Yoneda, Shigekazu

2018-01-01

Aqueous alteration is one of the primitive activities that occurred on meteorite parent bodies in the early solar system. The Tagish Lake meteorite is known to show an intense parent body aqueous alteration signature. In this study, quantitative analyses of the alkaline elements and isotopic analyses of Sr and Ba from acid leachates of TL (C2-ungrouped) were performed to investigate effects of aqueous alteration. The main purpose of this study is to search for isotopic evidence of extinct 135Cs from the Ba isotopic analyses in the chemical separates from the Tagish Lake meteorite. Barium isotopic data from the leachates show variable 135Ba isotopic anomalies (ε = ‑2.6 ∼ +3.6) which correlatewith 137Ba and 138Ba suggesting a heterogeneous distribution of s- and r-rich nucleosynthetic components in the early solar system. The 87Rb–87Sr and 135Cs–135Ba decay systems on TL in this study do not provide any chronological information. The disturbance of the TL chronometers is likely a reflection of the selective dissolution of Cs and Rb given the relatively higher mobility of Cs and Rb compared to Ba and Sr, respectively, during fluid mineral interactions.

Method for ultra-trace cesium isotope ratio measurements from environmental samples using thermal ionization mass spectrometry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Snow, Mathew S.; Snyder, Darin C.; Mann, Nick R.

2015-05-01

135Cs/ 137Cs isotope ratios can provide the age, origin and history of environmental Cs contamination. Relatively high precision 135Cs/ 137Cs isotope ratio measurements from samples containing femtogram quantities of 137Cs are needed to accurately track contamination resuspension and redistribution following environmental 137Cs releases; however, mass spectrometric analyses of environmental samples are limited by the large quantities of ionization inhibitors and isobaric interferences which are present at relatively high concentrations in the environment. We report a new approach for Cs purification from environmental samples. An initial ammonium molybdophosphate-polyacrylonitrile (AMP-PAN) column provides a robust method for extracting Cs under a wide varietymore » of sample matrices and mass loads. Cation exchange separations using a second AMP-PAN column result in more than two orders of magnitude greater Cs/Rb separation factors than commercially available strong cation exchangers. Coupling an AMP-PAN cation exchanging step to a microcation column (AG50W resin) enables consistent 2-4% (2σ) measurement errors for samples containing 3-6,000 fg 137Cs, representing the highest precision 135Cs/ 137Cs ratio measurements currently reported for soil samples at the femtogram level.« less

Tooth enamel maturation reequilibrates oxygen isotope compositions and supports simple sampling methods

NASA Astrophysics Data System (ADS)

Trayler, Robin B.; Kohn, Matthew J.

2017-02-01

Oxygen isotope and major element zoning patterns of several disparate ungulate teeth were collected to evaluate the timing and geometry of enamel formation, records of isotope zoning, and tooth enamel sampling strategies. Isotopic zoning in mammalian tooth enamel encodes a sub-annual time series of isotopic variation of an animal's body water composition, with a damping factor that depends on the specifics of how enamel mineralizes. Enamel formation comprises two stages: precipitation of appositional enamel with a high CO3:PO4 ratio, followed by precipitation of maturational enamel with a lower CO3:PO4. If appositional and maturational enamel both contribute to isotope compositions (but with different CO3:PO4), and if isotope compositions vary seasonally, paired δ18O values from CO3 and PO4 profiles should show a spatial separation. CO3 isotope patterns should be shifted earlier seasonally than PO4 isotope patterns. Such paired profiles for new and published data show no resolvable shifts, i.e. CO3 and PO4 δ18O profiles show coincident maxima and minima. This coincidence suggests that enamel maturation reequilibrates appositional isotope compositions. If enamel maturation establishes enamel isotope compositions, the geometry of maturation, not apposition, should be considered when devising sampling protocols. X-ray maps of Ca zoning show that the majority of enamel (inner and middle layers) mineralizes heavily at a high angle to the external tooth surface and the enamel-dentine junction over length scales of 2-4 mm, while the outer enamel surface mineralizes more slowly. These data suggest that isotopic sampling strategies should parallel maturational geometry and focus on interior enamel to improve data fidelity. The magnitude of isotopic damping is also smaller than implied in previous studies, so tooth enamel zoning more closely reflects original body water isotopic variations than previously assumed.

Isotopic variations of dissolved copper and zinc in stream waters affected by historical mining

USGS Publications Warehouse

Borrok, D.M.; Nimick, D.A.; Wanty, R.B.; Ridley, W.I.

2008-01-01

Zinc and Cu play important roles in the biogeochemistry of natural systems, and it is likely that these interactions result in mass-dependent fractionations of their stable isotopes. In this study, we examine the relative abundances of dissolved Zn and Cu isotopes in a variety of stream waters draining six historical mining districts located in the United States and Europe. Our goals were to (1) determine whether streams from different geologic settings have unique or similar Zn and Cu isotopic signatures and (2) to determine whether Zn and Cu isotopic signatures change in response to changes in dissolved metal concentrations over well-defined diel (24-h) cycles. Average ??66Zn and ??65Cu values for streams varied from +0.02??? to +0.46??? and -0.7??? to +1.4???, respectively, demonstrating that Zn and Cu isotopes are heterogeneous among the measured streams. Zinc or Cu isotopic changes were not detected within the resolution of our measurements over diel cycles for most streams. However, diel changes in Zn isotopes were recorded in one stream where the fluctuations of dissolved Zn were the largest. We calculate an apparent separation factor of ???0.3??? (66/64Zn) between the dissolved and solid Zn reservoirs in this stream with the solid taking up the lighter Zn isotope. The preference of the lighter isotope in the solid reservoir may reflect metabolic uptake of Zn by microorganisms. Additional field investigations must evaluate the contributions of soils, rocks, minerals, and anthropogenic components to Cu and Zn isotopic fluxes in natural waters. Moreover, rigorous experimental work is necessary to quantify fractionation factors for the biogeochemical reactions that are likely to impact Cu and Zn isotopes in hydrologic systems. This initial investigation of Cu and Zn isotopes in stream waters suggests that these isotopes may be powerful tools for probing biogeochemical processes in surface waters on a variety of temporal and spatial scales.

Fractionation of Cu and Zn isotopes during adsorption onto amorphous Fe(III) oxyhydroxide: Experimental mixing of acid rock drainage and ambient river water

USGS Publications Warehouse

Balistrieri, L.S.; Borrok, D.M.; Wanty, R.B.; Ridley, W.I.

2008-01-01

Fractionation of Cu and Zn isotopes during adsorption onto amorphous ferric oxyhydroxide is examined in experimental mixtures of metal-rich acid rock drainage and relatively pure river water and during batch adsorption experiments using synthetic ferrihydrite. A diverse set of Cu- and Zn-bearing solutions was examined, including natural waters, complex synthetic acid rock drainage, and simple NaNO3 electrolyte. Metal adsorption data are combined with isotopic measurements of dissolved Cu (65Cu/63Cu) and Zn (66Zn/64Zn) in each of the experiments. Fractionation of Cu and Zn isotopes occurs during adsorption of the metal onto amorphous ferric oxyhydroxide. The adsorption data are modeled successfully using the diffuse double layer model in PHREEQC. The isotopic data are best described by a closed system, equilibrium exchange model. The fractionation factors (??soln-solid) are 0.99927 ?? 0.00008 for Cu and 0.99948 ?? 0.00004 for Zn or, alternately, the separation factors (??soln-solid) are -0.73 ?? 0.08??? for Cu and -0.52 ?? 0.04??? for Zn. These factors indicate that the heavier isotope preferentially adsorbs onto the oxyhydroxide surface, which is consistent with shorter metal-oxygen bonds and lower coordination number for the metal at the surface relative to the aqueous ion. Fractionation of Cu isotopes also is greater than that for Zn isotopes. Limited isotopic data for adsorption of Cu, Fe(II), and Zn onto amorphous ferric oxyhydroxide suggest that isotopic fractionation is related to the intrinsic equilibrium constants that define aqueous metal interactions with oxyhydroxide surface sites. Greater isotopic fractionation occurs with stronger metal binding by the oxyhydroxide with Cu > Zn > Fe(II).

Copper isotopic zonation in the Northparkes porphyry Cu-Au deposit, SE Australia

NASA Astrophysics Data System (ADS)

Li, Weiqiang; Jackson, Simon E.; Pearson, Norman J.; Graham, Stuart

2010-07-01

Significant, systematic Cu isotopic variations have been found in the Northparkes porphyry Cu-Au deposit, NSW, Australia, which is an orthomagmatic porphyry Cu deposit. Copper isotope ratios have been measured in sulfide minerals (chalcopyrite and bornite) by both solution and laser ablation multi-collector inductively coupled plasma-mass spectrometry (MC-ICP-MS). The results from both methods show a variation in δ 65Cu of hypogene sulfide minerals of greater than 1‰ (relative to NIST976). Significantly, the results from four drill holes through two separate ore bodies show strikingly similar patterns of Cu isotope variation. The patterns are characterized by a sharp down-hole decrease from up to 0.8‰ (0.29 ± 0.56‰, 1 σ, n = 20) in the low-grade peripheral alteration zones (phyllic-propylitic alteration zone) to a low of ˜-0.4‰ (-0.25 ± 0.36‰, 1 σ, n = 30) at the margins of the most mineralized zones (Cu grade >1 wt%). In the high-grade cores of the systems, the compositions are more consistent at around 0.2‰ (0.19 ± 0.14‰, 1 σ, n = 40). The Cu isotopic zonation may be explained by isotope fractionation of Cu between vapor, solution and sulfides at high temperature, during boiling and sulfide precipitation processes. Sulfur isotopes also show an isotopically light shell at the margins of the high-grade ore zones, but these are displaced from the low δ 65Cu shells, such that there is no correlation between the Cu and S isotope signatures. Fe isotope data do not show any discernable variation along the drill core. This work demonstrates that Cu isotopes show a large response to high-temperature porphyry mineralizing processes, and that they may act as a vector to buried mineralization.

Isotopic separation of He-3/He-4 from solar wind gases evolved from the lunar regolith

NASA Astrophysics Data System (ADS)

Wilkes, William R.; Wittenberg, Layton J.

The potential benefits of He-3 when utilized in a nuclear fusion reactor to provide clean, safe electricity in the 21st century for the world's inhabitants has been documented. Unfortunately, He is scarce on earth. Large quantities of He-3, perhaps a million tons, are embedded in the lunar regolith, presumably implanted by the solar wind together with other elements, notably He-4, H, C, and N. Several studies have suggested processing the lunar regolith and recovering these valuable solar wind gases. Once released, these gases can be separated for use. The separation of helium isotopes is described in this paper. He-3 constitutes only 400 at. ppm of lunar He, too dilute to separate economically by distillation alone. A 'superfluid' separator is being considered to preconcentrate the He-3. The superfluid separator consists of a porous filter in a tube maintained at a temperature of 2.17 K or less. Although the He-4, which is superfluid below 2.17 K, flows readily through the filter, the He is blocked by the filter, and becomes enriched at the feed end. He can be enriched to about 10 percent in such a system. The enriched product from the superfluid separation serves as a feed to a distillation apparatus operating at a pressure of 9 kPa, with a boiler temperature of 2.4 K, and a condenser temperature of 1.6 K. Under constant flow conditions, a 99.9 percent enriched He product can be produced in this apparatus. The heat rejection load of the refrigeration equipment necessary to cool the separation operations would be conducted during the lunar nights.

Numerical modeling and optimization of the Iguassu gas centrifuge

NASA Astrophysics Data System (ADS)

Bogovalov, S. V.; Borman, V. D.; Borisevich, V. D.; Tronin, V. N.; Tronin, I. V.

2017-07-01

The full procedure of the numerical calculation of the optimized parameters of the Iguassu gas centrifuge (GC) is under discussion. The procedure consists of a few steps. On the first step the problem of a hydrodynamical flow of the gas in the rotating rotor of the GC is solved numerically. On the second step the problem of diffusion of the binary mixture of isotopes is solved. The separation power of the gas centrifuge is calculated after that. On the last step the time consuming procedure of optimization of the GC is performed providing us the maximum of the separation power. The optimization is based on the BOBYQA method exploring the results of numerical simulations of the hydrodynamics and diffusion of the mixture of isotopes. Fast convergence of calculations is achieved due to exploring of a direct solver at the solution of the hydrodynamical and diffusion parts of the problem. Optimized separative power and optimal internal parameters of the Iguassu GC with 1 m rotor were calculated using the developed approach. Optimization procedure converges in 45 iterations taking 811 minutes.

Radiochemical Applications of Insoluble Sulfate Columns. Analytical Possibilities in the Field of the Fission Product Solutions; APLICACIONES RADIO-QUIMICAS DE LAS COLUMNAS DE PRECIPITADOS DE SULFATOS INSOLUBLES. CONTRIBUCION AL ESTUDIO DE LAS SOLUCIONES ENVEJECIDAS DE PRODUCTOS DE FISION

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barrachina, M.; Sauvagnac, R.

1962-01-01

The heterogeneous ion-isotopic exchange column is used to determine the radiochemical composition of raw solutions used in the industrial recuperation of long-lived fission products, The separation of the radioelements is made by small columns, 1--3 cm height, of BaSO/sub 4/ or SrSO/sub 4/, under selected experimental conditions. These columns behave like inorganic exchangers, working by adsorption or ion-isotopic exchange depending on the cases, and they provide selective separation of fission products employing very small volumes of fixing and eluting solutions. By coupling the separative capabilities of these columns and the liquid--liquid extraction with the 2-thenoyltrifluoroacetone and the di-2 ethylexyl orthophosphoricmore » acid, a set of new radiochemical methods, for the determination of Sr/sup 90/, Y/sup 90/, Ce/sup 144/ - Pr/sup 144/, and Pm/sup 147/ in the fission product solutions of Marcoule, were developed. (auth)« less

Rapid determination of actinides in asphalt samples

DOE PAGES

Maxwell, Sherrod L.; Culligan, Brian K.; Hutchison, Jay B.

2014-01-12

A new rapid method for the determination of actinides in asphalt samples has been developed that can be used in emergency response situations or for routine analysis If a radiological dispersive device (RDD), Improvised Nuclear Device (IND) or a nuclear accident such as the accident at the Fukushima Nuclear Power Plant in March, 2011 occurs, there will be an urgent need for rapid analyses of many different environmental matrices, including asphalt materials, to support dose mitigation and environmental clean up. The new method for the determination of actinides in asphalt utilizes a rapid furnace step to destroy bitumen and organicsmore » present in the asphalt and sodium hydroxide fusion to digest the remaining sample. Sample preconcentration steps are used to collect the actinides and a new stacked TRU Resin + DGA Resin column method is employed to separate the actinide isotopes in the asphalt samples. The TRU Resin plus DGA Resin separation approach, which allows sequential separation of plutonium, uranium, americium and curium isotopes in asphalt samples, can be applied to soil samples as well.« less

Geochemistry of thermal water from selected wells, Boise, Idaho

USGS Publications Warehouse

Mariner, R.H.; Young, H.W.; Parliman, D.J.; Evans, William C.

1989-01-01

Samples of thermal water from selected wells in the Boise area were analyzed for chemical composition; stable isotopes of hydrogen, oxygen, and dissolved carbon; radioactive carbon; and dissolved-gas concentrations. Chemically, the waters are virtually identical to those of the adjacent Idaho batholith. Isotopically, the thermal waters are more depleted in deuterium and oxygen-18 than coldwater springs in the presumed recharge area. Chemical and isotopic data indicate the presence of two separate geothermal systems. Radioactive carbon and dissolved helium concentrations are interpreted to indicate recharge during the Pleistocene. Hot water in or southeast of Boise probably recharged 20,000 to 30,000 years ago, and warm water 2.5 miles northwest of Boise probably recharged at least 15,000 years ago.

Determination of uranium isotopes in environmental samples by anion exchange in sulfuric and hydrochloric acid media.

PubMed

Popov, L

2016-09-01

Method for determination of uranium isotopes in various environmental samples is presented. The major advantages of the method are the low cost of the analysis, high radiochemical yields and good decontamination factors from the matrix elements, natural and man-made radionuclides. The separation and purification of uranium is attained by adsorption with strong base anion exchange resin in sulfuric and hydrochloric acid media. Uranium is electrodeposited on a stainless steel disk and measured by alpha spectrometry. The analytical method has been applied for the determination of concentrations of uranium isotopes in mineral, spring and tap waters from Bulgaria. The analytical quality was checked by analyzing reference materials. Copyright © 2016 Elsevier Ltd. All rights reserved.

Atomic vapor laser isotope separation of lead-210 isotope

DOEpatents

Scheibner, K.F.; Haynam, C.A.; Johnson, M.A.; Worden, E.F.

1999-08-31

An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207. 5 figs.

Atomic vapor laser isotope separation of lead-210 isotope

DOEpatents

Scheibner, Karl F.; Haynam, Christopher A.; Johnson, Michael A.; Worden, Earl F.

1999-01-01

An isotopically selective laser process and apparatus for removal of Pb-210 from natural lead that involves a one-photon near-resonant, two-photon resonant excitation of one or more Rydberg levels, followed by field ionization and then electrostatic extraction. The wavelength to the near-resonant intermediate state is counter propagated with respect to the second wavelength required to populate the final Rydberg state. This scheme takes advantage of the large first excited state cross section, and only modest laser fluences are required. The non-resonant process helps to avoid two problems: first, stimulated Raman Gain due to the nearby F=3/2 hyperfine component of Pb-207 and, second, direct absorption of the first transition process light by Pb-207.

Heterodyne laser spectroscopy system

DOEpatents

Wyeth, Richard W.; Paisner, Jeffrey A.; Story, Thomas

1989-01-01

A heterodyne laser spectroscopy system utilizes laser heterodyne techniques for purposes of laser isotope separation spectroscopy, vapor diagnostics, processing of precise laser frequency offsets from a reference frequency and the like, and provides spectral analysis of a laser beam.

Origin of Spinel Framboids in Calcium-Aluminum-Rich Inclusions

NASA Astrophysics Data System (ADS)

Yoshizaki, T.; Nakashima, D.; Nakamura, T.; Ishida, H.; Sakamoto, N.

2017-07-01

Mineralogical, petrological and O-isotopic study of a CV CAI suggests that spinel framboids in the CAI were originally mini-CAIs that condensed separately under different conditions and subsequently aggregated to form the inclusion.

Isotope dilution inductively coupled plasma quadrupole mass spectrometry in connection with a chromatographic separation for ultra trace determinations of platinum group elements (Pt, Pd, Ru, Ir) in environmental samples.

PubMed

Müller, M; Heumann, K G

2000-09-01

An isotope dilution inductively coupled plasma quadrupole mass spectrometric (ID-ICP-QMS) method was developed for the simultaneous determination of the platinum group elements Pt, Pd, Ru, and Ir in environmental samples. Spike solutions, enriched with the isotopes 194Pt, 108Pd, 99Ru, and 191Ir, were used for the isotope dilution step. Interfering elements were eliminated by chromatographic separation using an anion-exchange resin. Samples were dissolved with aqua regia in a high pressure asher. Additional dissolution of possible silicate portions by hydrofluoric acid was usually not necessary. Detection limits of 0.15 ng x g(-1), 0.075 ng x g(-1), and 0.015 ng x g(-1) were achieved for Pt, Pd, Ru, and Ir, respectively, using sample weights of only 0.2 g. The reliability of the ID-ICP-QMS method was demonstrated by analyzing a Canadian geological reference material and by participating in an interlaboratory study for the determination of platinum and palladium in a homogenized road dust sample. Surface soil, sampled at different distances from a highway, showed concentrations in the range of 0.1-87 ng x g(-1). An exponential decrease of the platinum and palladium concentration with increasing distance and a small anthropogenic contribution to the natural background concentration of ruthenium and iridium was found in these samples.

The Radio Frequency Fragment Separator for Rare Isotope Beams at the NSCL

NASA Astrophysics Data System (ADS)

Stoker, Joshua; Andreev, Vladimir; Bazin, Daniel; Becerril, Ana; Doleans, Marc; Gorelov, Dimitry; Glennon, Patrick; Grimm, Terry; Lawton, Don; Mantica, Paul; Marti, Felix; Ottarson, Jack; Schatz, Hendrik; Vincent, John; Wagner, Jim; Wu, Xiaoyu; Zeller, Al

2006-10-01

Secondary beams at the National Superconducting Cyclotron Laboratory (NSCL) are separated through a combined application of magnetic rigidity and energy loss filtering. Design and construction of a Radio Frequency Fragment Separator (RFFS) for further beam purification is underway. The RFFS will apply a time-varying electromagnetic field to induce transverse beam separation. This method relies on velocity differences of the beam species to selectivey apply separation to unwanted fragments. The technical design of the RFFS and the expected purification of exotic beams are shown in detail[1]. [1] Gorelev, D. et al., ``RF Kicker System for Secondary Beams at the NSCL'' Proc of Part Accel Conf 2005, Knoxville, TN

Numerical Modeling of Dependence of Separative Power of the Gas Centrifuge on the Length of Rotor

NASA Astrophysics Data System (ADS)

Bogovalov, S. V.; Borisevich, V. D.; Borman, V. D.; Tronin, I. V.; Tronin, V. N.

Numerical modelling and optimization of the gas flow and isotope separation in the Iguasu gas centrifuge (GC) for uranium enrichment have been performed for different lengths of the rotor. The calculations show that the specific separative power of the GC reduces with the length of the rotor. We show that the reduction of the specific separative power is connected with the growth of the pressure in the optimal regime and corresponding growth of temperature to prevent the working gas sublimation. The specific separative power remains constant with the growth of the rotor length provided that the temperature of the rotor is taken to be constant.

Mixed-mode chromatography/isotope ratio mass spectrometry.

PubMed

McCullagh, James S O

2010-03-15

Liquid chromatography coupled to molecular mass spectrometry (LC/MS) has been a standard technique since the early 1970s but liquid chromatography coupled to high-precision isotope ratio mass spectrometry (LC/IRMS) has only been available commercially since 2004. This development has, for the first time, enabled natural abundance and low enrichment delta(13)C measurements to be applied to individual analytes in aqueous mixtures creating new opportunities for IRMS applications, particularly for the isotopic study of biological molecules. A growing number of applications have been published in a range of areas including amino acid metabolism, carbohydrates studies, quantification of cellular and plasma metabolites, dietary tracer and nucleic acid studies. There is strong potential to extend these to new compounds and complex matrices but several challenges face the development of LC/IRMS methods. To achieve accurate isotopic measurements, HPLC separations must provide baseline-resolution between analyte peaks; however, the design of current liquid interfaces places severe restrictions on compatible flow rates and in particular mobile phase compositions. These create a significant challenge on which reports associated with LC/IRMS have not previously focused. Accordingly, this paper will address aspects of chromatography in the context of LC/IRMS, in particular focusing on mixed-mode separations and their benefits in light of these restrictions. It aims to provide an overview of mixed-mode stationary phases and of ways to improve high aqueous separations through manipulation of parameters such as column length, temperature and mobile phase pH. The results of several practical experiments are given using proteogenic amino acids and nucleosides both of which are of noted importance in the LC/IRMS literature. This communication aims to demonstrate that mixed-mode stationary phases provide a flexible approach given the constraints of LC/IRMS interface design and acts as a practical guide for the development of new chromatographic methods compatible with LC/IRMS applications. Copyright 2010 John Wiley & Sons, Ltd.

Analytical Validation of Accelerator Mass Spectrometry for Pharmaceutical Development: the Measurement of Carbon-14 Isotope Ratio.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keck, B D; Ognibene, T; Vogel, J S

2010-02-05

Accelerator mass spectrometry (AMS) is an isotope based measurement technology that utilizes carbon-14 labeled compounds in the pharmaceutical development process to measure compounds at very low concentrations, empowers microdosing as an investigational tool, and extends the utility of {sup 14}C labeled compounds to dramatically lower levels. It is a form of isotope ratio mass spectrometry that can provide either measurements of total compound equivalents or, when coupled to separation technology such as chromatography, quantitation of specific compounds. The properties of AMS as a measurement technique are investigated here, and the parameters of method validation are shown. AMS, independent of anymore » separation technique to which it may be coupled, is shown to be accurate, linear, precise, and robust. As the sensitivity and universality of AMS is constantly being explored and expanded, this work underpins many areas of pharmaceutical development including drug metabolism as well as absorption, distribution and excretion of pharmaceutical compounds as a fundamental step in drug development. The validation parameters for pharmaceutical analyses were examined for the accelerator mass spectrometry measurement of {sup 14}C/C ratio, independent of chemical separation procedures. The isotope ratio measurement was specific (owing to the {sup 14}C label), stable across samples storage conditions for at least one year, linear over 4 orders of magnitude with an analytical range from one tenth Modern to at least 2000 Modern (instrument specific). Further, accuracy was excellent between 1 and 3 percent while precision expressed as coefficient of variation is between 1 and 6% determined primarily by radiocarbon content and the time spent analyzing a sample. Sensitivity, expressed as LOD and LLOQ was 1 and 10 attomoles of carbon-14 (which can be expressed as compound equivalents) and for a typical small molecule labeled at 10% incorporated with {sup 14}C corresponds to 30 fg equivalents. AMS provides an sensitive, accurate and precise method of measuring drug compounds in biological matrices.« less

LU-HF Age of Martian Meteorite Larkman Nunatek 06319

NASA Technical Reports Server (NTRS)

Shafer, J. T.; Brandon, A. D.; Lapen, T. J.; Righter, M.; Beard, B.; Peslier, A. H.

2009-01-01

Lu-Hf isotopic data were collected on mineral separates and bulk rock powders of LAR 06319, yielding an age of 197+/- 29 Ma. Sm-Nd isotopic data and in-situ LA-ICP-MS data from a thin section of LAR 06319 are currently being collected and will be presented at the 2009 LPSC. These new data for LAR 06319 extend the existing data set for the enriched shergottite group. Martian meteorites represent the only opportunity for ground truth investigation of the geochemistry of Mars [1]. At present, approximately 80 meteorites have been classified as Martian based on young ages and distinctive isotopic signatures [2]. LAR 06319 is a newly discovered (as part of the 2006 ANSMET field season) martian meteorite that represents an important opportunity to further our understanding of the geochemical and petrological constraints on the origin of Martian magmas. Martian meteorites are traditionally categorized into the shergottite, nakhlite, and chassignite groups. The shergottites are further classified into three distinct isotopic groups designated depleted, intermediate, and enriched [3,4] based on the isotope systematics and compositions of their source(s).

Capture of heavy hydrogen isotopes in a metal-organic framework with active Cu(I) sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weinrauch, Ingrid; Savchenko, Ievgeniia L.; Denysenko, D.

The production of pure deuterium and the removal of tritium from nuclear waste are the key challenges in separation of light isotopes. Presently, the technological methods are extremely energy- and cost-intensive. Here we report the capture of heavy hydrogen isotopes from hydrogen gas by selective adsorption at Cu(I) sites in a metal-organic framework. At the strongly binding Cu(I) sites (32 kJ mol -1) nuclear quantum effects result in higher adsorption enthalpies of heavier isotopes. The capture mechanism takes place most efficiently at temperatures above 80 K, when an isotope exchange allows the preferential adsorption of heavy isotopologues from the gasmore » phase. Large difference in adsorption enthalpy of 2.5 kJ mol -1 between D 2 and H 2 results in D 2-over-H 2 selectivity of 11 at 100 K, to the best of our knowledge the largest value known to date. Combination of thermal desorption spectroscopy, Raman measurements, inelastic neutron scattering and first principles calculations for H 2/D 2 mixtures allows the prediction of selectivities for tritium-containing isotopologues.« less

Capture of heavy hydrogen isotopes in a metal-organic framework with active Cu(I) sites

DOE PAGES

Weinrauch, Ingrid; Savchenko, Ievgeniia L.; Denysenko, D.; ...

2017-03-06

The production of pure deuterium and the removal of tritium from nuclear waste are the key challenges in separation of light isotopes. Presently, the technological methods are extremely energy- and cost-intensive. Here we report the capture of heavy hydrogen isotopes from hydrogen gas by selective adsorption at Cu(I) sites in a metal-organic framework. At the strongly binding Cu(I) sites (32 kJ mol -1) nuclear quantum effects result in higher adsorption enthalpies of heavier isotopes. The capture mechanism takes place most efficiently at temperatures above 80 K, when an isotope exchange allows the preferential adsorption of heavy isotopologues from the gasmore » phase. Large difference in adsorption enthalpy of 2.5 kJ mol -1 between D 2 and H 2 results in D 2-over-H 2 selectivity of 11 at 100 K, to the best of our knowledge the largest value known to date. Combination of thermal desorption spectroscopy, Raman measurements, inelastic neutron scattering and first principles calculations for H 2/D 2 mixtures allows the prediction of selectivities for tritium-containing isotopologues.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ionita, G.; Stefanescu, I.

The nature and performance of our patented catalysts, with platinum on carbon and polytetrafluorethylene [Pt/C/PTFE] and platinum on styrenedivynilbenzene and polystyrene [Pt/STB/PS], used in a water-hydrogen isotope exchange process are presented. The behaviour of the two catalysts in tritiated water was tested by determining their physical and structural characteristics as well as the catalytic activity before and after immersion in tritiated water. The test results emphasized that the two catalysts are highly active in the hydrogen - water vapor (H{sub 2(g)}-H{sub 2}O{sub (v)}) isotopic exchange and highly stable to tritium radiation. It was discovered that Pt/SDB/PS catalyst proved to bemore » quite unstable in the hydrogen- water vapor - water (H{sub 2(g)}-H{sub 2}O{sub (v)}-H{sub 2}O{sub (1)}) isotopic exchange, while the Pt/C/PTFE catalyst was highly stable. Thus, the Pt/C/PTFE catalyst was chosen for hydrogen isotope separation by liquid hydrogen cryogenic distillation combined with water - hydrogen isotopic exchange in a demonstration scale plant. 5 refs., 8 figs., 2 tabs.« less