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Sample records for isotope separation factor

  1. Isotope separation

    DOEpatents

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  2. 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.

  3. Isotope separation by photochromatography

    DOEpatents

    Suslick, K.S.

    1975-10-03

    A photochromatographic method for isotope separation is described. An isotopically mixed molecular species is adsorbed on an adsorptive surface, and the adsorbed molecules are irradiated with radiation of a predetermined wavelength which will selectively excite desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thus separate them from the undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes. (BLM)

  4. Isotope separation by photochromatography

    DOEpatents

    Suslick, Kenneth S.

    1977-01-01

    An isotope separation method which comprises physically adsorbing an isotopically mixed molecular species on an adsorptive surface and irradiating the adsorbed molecules with radiation of a predetermined wavelength which will selectively excite a desired isotopic species. Sufficient energy is transferred to the excited molecules to desorb them from the surface and thereby separate them from the unexcited undesired isotopic species. The method is particularly applicable to the separation of hydrogen isotopes.

  5. Method for separating isotopes

    DOEpatents

    Jepson, B.E.

    1975-10-21

    Isotopes are separated by contacting a feed solution containing the isotopes with a cyclic polyether wherein a complex of one isotope is formed with the cyclic polyether, the cyclic polyether complex is extracted from the feed solution, and the isotope is thereafter separated from the cyclic polyether.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. ISOTOPE SEPARATING APPARATUS CONTROL

    DOEpatents

    Barnes, S.W.

    1959-08-25

    An improved isotope separating apparatus of the electromagnetic type, commonly referred to as a calutron, is described. Improvements in detecting and maintaining optimum position and focus of the ion beam are given. The calutron collector is provided with an additional electrode insulated from and positioned between the collecting pockets. The ion beams are properly positioned and focused until the deionizing current which flows from ground to this additional electrode ts a minimum.

  14. High Atomic Weight Isotope Separator.

    DTIC Science & Technology

    This patent discusses a method of separating one isotopic species of a given element from a mixture. Collisionless plasma instabilities slow down the ions and oppositely charged electrodes separate the isotopes.

  15. Method for separating boron isotopes

    DOEpatents

    Rockwood, Stephen D.

    1978-01-01

    A method of separating boron isotopes .sup.10 B and .sup.11 B by laser-induced selective excitation and photodissociation of BCl.sub.3 molecules containing a particular boron isotope. The photodissociation products react with an appropriate chemical scavenger and the reaction products may readily be separated from undissociated BCl.sub.3, thus effecting the desired separation of the boron isotopes.

  16. 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.

  17. 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.

  18. 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.

  19. Hydrograph separation using stable isotopes: Review and evaluation

    NASA Astrophysics Data System (ADS)

    Klaus, J.; McDonnell, J. J.

    2013-11-01

    We reviewed isotope hydrograph separation studies.We examine methods, applications, and limitations.We summarize factors that control the event/pre-event water contributions.We outline new possible research avenues in isotope hydrograph separation.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Beam delivery for stable isotope separation

    NASA Astrophysics Data System (ADS)

    Forbes, Andrew; Strydom, Hendrick J.; Botha, Lourens R.; Ronander, Einar

    2002-10-01

    In the multi-photon dissociation process of Carbon isotope enrichment, IR photons are used to selectively excite a molecule with the given isotopic base element. This enrichment process is very sensitive to the beam's intensity and wavelength. Because the intensity is determined by the propagation of the field, the enrichment factors are also very dependent on the field propagation. In this paper, the influence of the wavelength and intensity of the beam, on the isotope selective dissociation of a CFC compound is investigated both experimentally and theoretically. Consideration is also given to some of the factors that influence the delivery of various beams to the reactor chamber, and their subsequent propagation through the reactor. The results show that suitable beam forming can lead to an improved isotope separation process.

  6. Apparatus and process for separating hydrogen isotopes

    DOEpatents

    Heung, Leung K; Sessions, Henry T; Xiao, Xin

    2013-06-25

    The apparatus and process for separating hydrogen isotopes is provided using dual columns, each column having an opposite hydrogen isotopic effect such that when a hydrogen isotope mixture feedstock is cycled between the two respective columns, two different hydrogen isotopes are separated from the feedstock.

  7. Atomic vapor laser isotope separation

    SciTech Connect

    Stern, R.C.; Paisner, J.A.

    1985-11-08

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power reactor fuel has been under development for over 10 years. In June 1985 the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for the internationally competitive production of uranium separative work. The economic basis for this decision is considered, with an indicated of the constraints placed on the process figures of merit and the process laser system. We then trace an atom through a generic AVLIS separator and give examples of the physical steps encountered, the models used to describe the process physics, the fundamental parameters involved, and the role of diagnostic laser measurements.

  8. The separation of stable isotopes of carbon

    NASA Astrophysics Data System (ADS)

    Oziashvili, E. D.; Egiazarov, A. S.

    1989-04-01

    The present state of work on the separation of carbon isotopes by diffusion, fractional distillation, chemical isotopic exchange, and the selective excitation and dissociation of molecules in electrical discharges or in the field of laser radiation has been examined. The characteristics of new laboratory and industrial assemblies for separating carbon isotopes have been described. Promising directions of study aimed at developing effective technological processes for separating carbon isotopes have been noted. The bibliography contains 148 references.

  9. Laser system for isotope separation

    NASA Astrophysics Data System (ADS)

    Shirayama, Shimpey; Mikatsura, Takefumi; Ueda, Hiroaki; Konagai, Chikara

    1990-06-01

    Atomic vapor laser isotope separation (AVLIS) is regarded as the most promising method to obtain srightly enriched economical nuclear fuel for a nuclear power plant. However, achieving a high power laser seems to be the bottle neck in its industrialization. In 1985, after successful development of high power lasers, the U.S. announced that AVLIS would be used for future methods of uranium enrichment. In Japan , Laser Atomic Separation Enrichment Research Associates of Japan (LASER-J), a joint Japanese utility companies research organization, was founded in April, 1987, to push a development program for laser uranium enrichment. Based on research results obtained from Japanese National Labs, and Universities , Laser-J is now constructing an AVLIS experimental facility at Tokai-mura. It is planned to have a 1-ton swu capacity per year in 1991. Previous to the experimental facility construction , Toshiba proceeded with the preliminary testing of an isotope separation system, under contract with Laser-J. Since the copper vapor laser (CVL) and the dye laser (DL) form a good combination , which can obtain high power tunable visible lights ,it is suitable to resonate uranium atoms. The laser system was built and was successfully operated in Toshiba for two years. The system consist of three copper vapor lasers , three dye lasers and appropriate o Atomic vapor laser isotope separation (AVLIS) is regarded as the most promising method to obtain srightly enriched economical nuclear fuel for a nuclear power plant. However, achieving a high power laser seems to be the bottle neck in its industrialization. In 1985, after successful development of high power lasers, the U.S. announced that AVLIS would be used for future methods of uranium enrichment. In Japan , Laser Atomic Separation Enrichment Research Associates of Japan (LASER-J) , a joint Japanese utility companies research organization , was founded in April, 1987, to push a development program for laser uranium enrichment

  10. 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.

  11. 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.

  12. Method of separating boron isotopes

    SciTech Connect

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

    1984-05-08

    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/.

  13. 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/.

  14. 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.

  15. Hydrogen isotope separation installation for tritium facility

    SciTech Connect

    Andreev, B.M.; Perevezentsev, A.N.; Selivanenko, I.L.; Tenyaev, B.N.; Vedeneev, A.I.; Golubkov, A.N.

    1995-10-01

    The separation of hydrogen isotopes in the hydrogen-palladium system in sectioned separation columns with the simulation of counter-current isotopic exchange is described. The separation efficiency of sectioned columns is investigated with the experimental installation as a function of various parameters. The separation of deuterium-tritium mixtures with high tritium concentrations is tested with the pilot installation operating at room temperature and atmospheric hydrogen pressure. Due to very high separation efficiency, flexibility and simplicity of operation separation installations with sectioned columns are ideally suitable for tritium laboratories and facilities dealing with separation of hydrogen isotopes. Estimation of applicability of sectioned columns for regeneration of exhaust gas in a fuel cycle of thermonuclear reactors, such as JET and ITER, shows the number of advantages of separation installations with sectioned columns. 12 refs., 3 figs., 2 tabs.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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)

  2. Laser Isotope Separation Employing Condensation Repression

    SciTech Connect

    Eerkens, Jeff W.; Miller, William H.

    2004-09-15

    Molecular laser isotope separation (MLIS) techniques using condensation repression (CR) harvesting are reviewed and compared with atomic vapor laser isotope separation (AVLIS), gaseous diffusion (DIF), ultracentrifuges (UCF), and electromagnetic separations (EMS). Two different CR-MLIS or CRISLA (Condensation Repression Isotope Separation by Laser Activation) approaches have been under investigation at the University of Missouri (MU), one involving supersonic super-cooled free jets and dimer formation, and the other subsonic cold-wall condensation. Both employ mixtures of an isotopomer (e.g. {sup i}QF{sub 6}) and a carrier gas, operated at low temperatures and pressures. Present theories of VT relaxation, dimerization, and condensation are found to be unsatisfactory to explain/predict experimental CRISLA results. They were replaced by fundamentally new models that allow ab-initio calculation of isotope enrichments and predictions of condensation parameters for laser-excited and non-excited vapors which are in good agreement with experiment. Because of supersonic speeds, throughputs for free-jet CRISLA are a thousand times higher than cold-wall CRISLA schemes, and thus preferred for large-quantity Uranium enrichments. For small-quantity separations of (radioactive) medical isotopes, the simpler coldwall CRISLA method may be adequate.

  3. 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.

  4. 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.

  5. Isotope separation and advanced manufacturing technology

    NASA Astrophysics Data System (ADS)

    Carpenter, J.; Kan, T.

    This is the fourth issue of a semiannual report for the Isotope Separation and Advanced Materials Manufacturing (ISAM) Technology Program at Lawrence Livermore National Laboratory. Primary objectives include: (1) the Uranium Atomic Vapor Laser Isotope Separation (UAVLIS) process, which is being developed and prepared for deployment as an advanced uranium enrichment capability; (2) Advanced manufacturing technologies, which include industrial laser and E-beam material processing and new manufacturing technologies for uranium, plutonium, and other strategically important materials in support of DOE and other national applications. This report features progress in the ISAM Program from October 1993 through March 1994.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Hydrogen isotope separation utilizing bulk getters

    SciTech Connect

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

    1990-12-11

    This patent describes hydrogen isotope separation utilizing bulk getters. 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.

  11. 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.

  12. 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.

  13. 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.

  14. Production of stable isotopes utilizing the plasma separation process

    NASA Astrophysics Data System (ADS)

    Bigelow, T. S.; Tarallo, F. J.; Stevenson, N. R.

    2005-12-01

    A plasma separation process (PSP) is being operated at Theragenics Corporation's®, Oak Ridge, TN, facility for the enrichment of stable isotopes. The PSP utilizes ion cyclotron mass discrimination to separate isotopes on a relatively large scale. With a few exceptions, nearly any metallic element could be processed with PSP. Output isotope enrichment factor depends on natural abundance and mass separation and can be fairly high in some cases. The Theragenics™ PSP facility is believed to be the only such process currently in operation. This system was developed and formerly operated under the US Department of Energy Advanced Isotope Separation program. Theragenics™ also has a laboratory at the PSP site capable of harvesting the isotopes from the process and a mass spectrometer system for analyzing enrichment and product purity. Since becoming operational in 2002, Theragenics™ has utilized the PSP to separate isotopes of several elements including: dysprosium, erbium, gadolinium, molybdenum and nickel. Currently, Theragenics™ is using the PSP for the separation of 102Pd, which is used as precursor for the production of 103Pd. The 103Pd radioisotope is the active ingredient in TheraSeed®, which is used in the treatment of early stage prostate cancer and being investigated for other medical applications. New industrial, medical and research applications are being investigated for isotopes that can be enriched on the PSP. Pre-enrichment of accelerator or reactor targets offers improved radioisotope production. Theragenics operates 14 cyclotrons for proton activation and has access to HFIR at ORNL for neutron activation of radioisotopes.

  15. 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.

  16. Gas chromatographic separation of hydrogen isotopes using metal hydrides

    SciTech Connect

    Aldridge, F.T.

    1984-05-09

    A study was made of the properties of metal hydrides which may be suitable for use in chromatographic separation of hydrogen isotopes. Sixty-five alloys were measured, with the best having a hydrogen-deuterium separation factor of 1.35 at 60/sup 0/C. Chromatographic columns using these alloys produced deuterium enrichments of up to 3.6 in a single pass, using natural abundance hydrogen as starting material. 25 references, 16 figures, 4 tables.

  17. 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)

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. An isotope separator for small noble gas samples

    NASA Astrophysics Data System (ADS)

    Lehmann, B. E.; Rauber, D. F.; Thonnard, N.; Willis, R. D.

    1987-11-01

    A Wien filter isotope enrichment system has been combined with a small turbomolecular pump to form a closed isotope separator for small noble gas samples. Atoms which leave the exit aperture of the plasma discharge ion source without being ionized are circulated back into the source through a feedback line. The system can be operated for several hours in a closed mode to collect up to 50% of the total number of atoms of a selected isotope (e.g. 81Kr) out of a small gas sample of only 2 × 10 -3 cm 3 STP. Ions are implanted at 10 kV into an aluminized Kapton foil after a flight distance of 150 cm. A beam stabilization system centers the ion beam in two perpendicular directions onto a target aperture to maintain a high enrichment factor of at least 10 3 over extended periods of time. Calibration of the enrichment process is achieved by isotope dilution. The system is a key part of the sample processing for 81Kr and 85Kr analysis by laser resonance ionization spectroscopy for applications in isotope geophysics.

  5. 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.

  6. 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).

  7. 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.

  8. A LINEAR PROGRAMMING MODEL OF THE GASEOUSDIFFUSION ISOTOPE-SEPARATION PROCESS,

    DTIC Science & Technology

    ISOTOPE SEPARATION, LINEAR PROGRAMMING ), (*GASEOUS DIFFUSION SEPARATION, LINEAR PROGRAMMING ), (* LINEAR PROGRAMMING , GASEOUS DIFFUSION SEPARATION), NUCLEAR REACTORS, REACTOR FUELS, URANIUM, PURIFICATION

  9. Cost Estimate for Laser Isotope Separation for RIA

    SciTech Connect

    Scheibner, K

    2004-11-01

    Isotope enrichment of some elements is required in support of the Rare Isotope Accelerator (RIA) in order to obtain the beam intensities, source efficiencies and/or source lifetime required by RIA. The economics of using Atomic Vapor Laser Isotope Separation (AVLIS) technology as well as ElectroMagnetic (EM) separation technology has been evaluated. It is concluded that such an AVLIS would be about 10 times less expensive than a facility based on electromagnetic separation - $17 M versus $170 M. In addition, the AVLIS facility footprint would be about 10 times smaller, and operations would require about 4 years (including 2 years of startup) versus about 11 years for an EM facility.

  10. 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.

  11. Efficient isotope separation by single-photon atomic sorting

    SciTech Connect

    Jerkins, M.; Chavez, I.; Raizen, M. G.; Even, U.

    2010-09-15

    We propose a general and scalable approach to isotope separation. The method is based on an irreversible change of the mass-to-magnetic moment ratio of a particular isotope in an atomic beam, followed by a magnetic multipole whose gradients deflect and guide the atoms. The underlying mechanism is a reduction of the entropy of the beam by the information of a single scattered photon for each atom that is separated. We numerically simulate isotope separation for a range of examples, which demonstrate this technique's general applicability to almost the entire periodic table. The practical importance of the proposed method is that large-scale isotope separation should be possible, using ordinary inexpensive magnets and the existing technologies of supersonic beams and lasers.

  12. 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.

  13. tritium isotope separation by CO 2 laser-induced multiphoton dissociation of CTF 3

    NASA Astrophysics Data System (ADS)

    Makide, Yoshihiro; Hagiwara, Satoru; Tominaga, Takeshi; Takeuchi, Kazuo; Nakane, Ryohei

    1981-08-01

    Isotope separation of tritium at ppm concentration level was achieved by CO 2 laser-induced multiphoton dissociation of CTF 3 in CHF 3 with single-step separation factors exceeding 500. The effects of laser frequency, pulse energy, pulse duration, irradiation geometry, tritium concentration, sample pressure, and buffer gas were investigated.

  14. Cascades for hydrogen isotope separation using metal hydrides

    SciTech Connect

    Hill, F.B.; Grzetic, V.

    1982-01-01

    Designs are presented for continuous countercurrent hydrogen isotope separation cascades based on the use of metal hydrides. The cascades are made up of pressure swing adsorption (PSA) or temperature swing adsorption (TSA) stages. The designs were evolved from consideration of previously conducted studies of the separation performance of four types of PSA and TSA processes.

  15. Tritium Isotope Separation Using Adsorption-Distillation Column

    SciTech Connect

    Fukada, Satoshi

    2005-07-15

    In order to miniaturize the height of a distillation tower for the detritiation of waste water from fusion reactors, two experiments were conducted: (1) liquid frontal chromatography of tritium water eluting through an adsorption column and (2) water distillation using a column packed with adsorbent particles. The height of the distillation tower depends on the height equivalent to a theoretical plate, HETP, and the equilibrium isotope separation factor, {alpha}{sub H-T}{sup equi}. The adsorption action improved not only HETP but also {alpha}{sub H-T}{sup equi}. Since the adsorption-distillation method proposed here can shorten the tower height with keeping advantages of the distillation, it may bring an excellent way for miniaturizing the distillation tower to detritiate a large amount of waste water from fusion reactors.

  16. Electromagnetic separation of stable isotopes at China Institute of Atomic Energy

    NASA Astrophysics Data System (ADS)

    Meiqin, Xiao; Hongyou, Lu; Shijun, Su; Zhizhou, Lin

    1993-09-01

    Electromagnetic separation of stable isotopes at CIAE is described. The separators, the ion sources used, the isotopes separated and their applications are introduced. The improvement of a 180° production separator is also described.

  17. 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.

  18. Atomic vapor laser isotope separation of lead-210 isotope

    SciTech Connect

    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.

  19. Nitrogen isotopes of the mantle: Insights from mineral separates

    NASA Astrophysics Data System (ADS)

    Fischer, Tobias P.; Takahata, Naoto; Sano, Yuji; Sumino, Hirochika; Hilton, David R.

    2005-06-01

    We present the first nitrogen (N) isotope measurements determined by in-vacuo crushing of mineral separates from arc lavas, OIBs (Ocean Island Basalts), and mantle xenoliths. Measured OIB δ15N values range from ~-8‰ for the northern rift zone in Iceland to +3.1‰ for a dunite nodule from Hawaii. Most arc-related olivines show distinctly positive values - up to +6.2‰ (Cerro Negro, Nicaragua). The measured N isotope values in olivine separates are similar to gas samples collected at the same localities, suggesting that both media (olivines and gases) sample volatiles primarily derived from the magma. This observation also implies that N isotope fractionation does not occur during magma degassing, a notion supported by 4He/40Ar* data. Our results indicate a heterogeneous mantle source region, in terms of N isotopic composition, that may have resulted from surface recycling of N at some localities.

  20. 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.

  1. 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.

  2. 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.

  3. METHOD TO TEST ISOTOPIC SEPARATION EFFICIENCY OF PALLADIUM PACKED COLUMNS

    SciTech Connect

    Heung, L; Gregory Staack, G; James Klein, J; William Jacobs, W

    2007-06-27

    The isotopic effect of palladium has been applied in different ways to separate hydrogen isotopes for many years. At Savannah River Site palladium deposited on kieselguhr (Pd/k) is used in a thermal cycling absorption process (TCAP) to purify tritium for over ten years. The need to design columns for different throughputs and the desire to advance the performance of TCAP created the need to evaluate different column designs and packing materials for their separation efficiency. In this work, columns with variations in length, diameter and metal foam use, were tested using an isotope displacement method. A simple computer model was also developed to calculate the number of theoretical separation stages using the test results. The effects of column diameter, metal foam and gas flow rate were identified.

  4. Status of stable isotopes separation at the Electromagnetic Plants of the Russian Research Center, ``Kurchatov Institute''

    NASA Astrophysics Data System (ADS)

    Kouzmine, R. N.; Bondarenko, V. G.; Pigarov, Ju. D.; Staroverov, L. I.; Tchesnokov, V. M.

    1999-12-01

    The four chamber electromagnetic isotope separator was constructed at the Russian Research Center (RRC) "Kurchatov Institute" more than 50 years ago. During this period, the plant was used for the development of ion sources and separation technologies. Isotopes of over 40 different elements have been separated. About 20 years ago, the reconstruction of two chambers was completed. The homogeneous magnetic field in these chambers was replaced with a field which falls-off on the radius ( r) as 1/ r. After reconstruction, the dispersion was increased by a factor of four and the enrichment of the isotopes was increased considerably. Ion beam collection was also facilitated. Many highly enriched isotopes were produced in the new chambers, including Gd, Yb, Zn, Tl, Pd, and others. One of the important problems now, is the reduction of all aspects of production costs for isotopes. A project to perfect the ion-optic scheme (IOS) for two chambers was carried out with the expected result of a dispersion of 44 mm at 1% relative mass difference. As a result of the modified ion source, increased productivity of the separators is expected. Other areas of ion source development in progress include: development of "standard" ion sources for the separators with inhomogeneous fields, development of high-temperature sources for Pd isotopes, and development of an ion source with sputtering supply for Ir, Pt, and other elements.

  5. Pulsed CO laser for isotope separation of uranium

    SciTech Connect

    Baranov, Igor Y.; Koptev, Andrey V.

    2012-07-30

    This article proposes a technical solution for using a CO laser facility for the industrial separation of uranium used in the production of fuel for nuclear power plants, employing a method of laser isotope separation of uranium with condensation repression in a free jet. The laser operation with nanosecond pulse irradiation can provide an acceptable efficiency in the separating unit and a high efficiency of the laser with the wavelength of 5.3 {mu}m. In the present work we also introduce a calculation model and define the parameters of a mode-locked CO laser with a RF discharge in the supersonic stream. The average pulsed CO laser power of 3 kW is sufficient for efficient industrial isotope separation of uranium in one stage.

  6. Chromatographic separation of neodymium isotopes by using chemical exchange process.

    PubMed

    Ismail, I M; Ibrahim, M; Aly, H F; Nomura, M; Fujii, Y

    2011-05-20

    The neodymium isotope effects were investigated in Nd-malate ligand exchange system using the highly porous cation exchange resin SQS-6. The temperature of the chromatographic columns was kept constant at 50°C by temperature controlled water passed through the columns jackets. The separation coefficient of neodymium isotopes, ɛ's, was calculated from the isotopic ratios precisely measured by means of an ICP mass spectrometer equipped with nine collectors as ion detectors. The separation coefficient, ɛ×10(5), were calculated and found to be 1.4, 4.8, 5.4, 10.6, 16.8 and 20.2 for (143)Nd, (144)Nd, (145)Nd, (146)Nd, (148)Nd and (150)Nd, respectively.

  7. Production of rare isotope beams with the NSCL fragment separator

    NASA Astrophysics Data System (ADS)

    Stolz, A.; Baumann, T.; Ginter, T. N.; Morrissey, D. J.; Portillo, M.; Sherrill, B. M.; Steiner, M.; Stetson, J. W.

    2005-12-01

    Rare isotope beams at the National Superconducting Cyclotron Laboratory are produced by projectile fragmentation of medium energy primary beams on beryllium targets. The fragments of interest are selected by the A1900 high-acceptance fragment separator. The A1900 consists of superconducting magnets: four 45° dipoles and eight quadrupole triplets with a maximum magnetic rigidity of 6 Tm. A momentum acceptance of Δp/p = 5% with a solid angle acceptance of ΔΩ = 8 msr makes the A1900 one of the highest-acceptance separators in the world. Detector systems installed within the device allow tracking and unambiguous identification of individual isotopes. During the first three years of operation of the A1900, more than 200 different rare isotope beams approaching both the neutron and proton driplines have been delivered to experiments.

  8. THE SEPARATION OF URANIUM ISOTOPES BY GASEOUS DIFFUSION: A LINEAR PROGRAMMING MODEL,

    DTIC Science & Technology

    URANIUM, ISOTOPE SEPARATION), (*GASEOUS DIFFUSION SEPARATION, LINEAR PROGRAMMING ), (* LINEAR PROGRAMMING , GASEOUS DIFFUSION SEPARATION), MATHEMATICAL MODELS, GAS FLOW, NUCLEAR REACTORS, OPERATIONS RESEARCH

  9. 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)

  10. Rotation and instabilities for isotope and mass separation

    NASA Astrophysics Data System (ADS)

    Rax, J.-M.; Gueroult, R.

    2016-10-01

    Rotating plasmas have the potential to offer unique capabilities for isotope and mass separation. Among the various electric and magnetic field configurations offering mass separation capabilities, rotating plasmas produced through static or oscillating fields are shown to be a leading candidate for tackling the unsolved problem of large-scale plasma separation. The successful development and deployment of industrial-scale plasma separation technologies could, among many other applications, provide an innovative path towards advanced sustainable nuclear energy. In this context, the potential and versatility of plasma rotation induced by rotating magnetic fields is uncovered and analysed. Analytical stability diagrams are derived from rotating ion orbits as a function of ion mass. Based on these findings, the basic principles of a rotating field plasma separator are then introduced. In light of these results, challenges associated with this original separation process are underlined, and the main directions for a future research program aimed at this important unsolved problem of applied plasma physics are identified.

  11. Atomic vapor laser isotope separation using resonance ionization

    SciTech Connect

    Comaskey, B.; Crane, J.; Erbert, G.; Haynam, C.; Johnson, M.; Morris, J.; Paisner, J.; Solarz, R.; Worden, E.

    1986-09-01

    Atomic vapor laser isotope separation (AVLIS) is a general and powerful technique. A major present application to the enrichment of uranium for light-water power-reactor fuel has been under development for over 10 years. In June 1985, the Department of Energy announced the selection of AVLIS as the technology to meet the nation's future need for enriched uranium. Resonance photoionization is the heart of the AVLIS process. We discuss those fundamental atomic parameters that are necessary for describing isotope-selective resonant multistep photoionization along with the measurement techniques that we use. We illustrate the methodology adopted with examples of other elements that are under study in our program.

  12. 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.

  13. Advancement of isotope separation for the production of reference standards

    SciTech Connect

    Jared Horkley; Christopher McGrath; Andrew Edwards; Gaven Knighton; Kevin Carney; Jacob Davies; James Sommers; Jeffrey Giglio

    2012-03-01

    Idaho National Laboratory (INL) operates a mass separator that is currently producing high purity isotopes for use as internal standards for high precision isotope dilution mass spectrometry (IDMS). In 2008, INL began the revival of the vintage 1970’s era instrument. Advancements thus far include the successful upgrading and development of system components such as the vacuum system, power supplies, ion-producing components, and beam detection equipment. Progress has been made in the separation and collection of isotopic species including those of Ar, Kr, Xe, Sr, and Ba. Particular focuses on ion source improvements and developments have proven successful with demonstrated output beam currents of over 10 micro-amps 138Ba and 350nA 134Ba from a natural abundance source charge (approximately 2.4 percent 134Ba). In order to increase production and collection of relatively high quantities (mg levels) of pure isotopes, several advancements have been made in ion source designs, source material introduction, and beam detection and collection. These advancements and future developments will be presented.

  14. Development of Halide and Oxy-Halides for Isotopic Separations

    SciTech Connect

    Martin, Leigh R.; Johnson, Aaron T.; Pfeiffer, Jana; Finck, Martha R.

    2014-10-01

    The goal of this project was to synthesize a volatile form of Np for introduction into mass spectrometers at INL. Volatile solids of the 5f elements are typically those of the halides (e.g. UF6), however fluorine is highly corrosive to the sensitive internal components of the mass separator, and the other volatile halides exist as several different stable isotopes in nature. However, iodide is both mono-isotopic and volatile, and as such presents an avenue for creation of a form of Np suitable for introduction into the mass separator. To accomplish this goal, the technical work in the project sought to establish a novel synthetic route for the conversion NpO2+ (dissolved in nitric acid) to NpI3 and NpI4.

  15. NOVEL CONCEPTS FOR ISOTOPIC SEPARATION OF 3HE/4HE

    SciTech Connect

    Roy, L.; Nigg, H.; Watson, H.

    2012-09-04

    The research outlined below established theoretical proof-of-concept using ab initio calculations that {sup 3}He can be separated from {sup 4}He by taking advantage of weak van der Waals interactions with other higher molecular weight rare gases such as xenon. To the best of our knowledge, this is the only suggested method that exploits the physical differences of the isotopes using a chemical interaction.

  16. 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.

  17. Isotopic separation of lithium ions by capillary zone electrophoresis.

    PubMed

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

    2015-12-01

    Separation of (6)Li and (7)Li isotopes by CZE was demonstrated. The BGE contained 5 mM 4-aminopyridine, 0.9 mM oxalic acid, 0.25 mM CTAB, and 0.25% w/v Tween 20 (рН = 9.2). The running conditions were +25 kV at 30°C with indirect photometric detection at 261 nm. Under optimal experimental conditions, the analysis time was less than 21 min. Separation of Li preparations with mole fraction of (6)Li ranging from 3.44 up to 90.38% was demonstrated.

  18. CO2-laser isotope separation of tritium with pentafluoroethane-T (C2TF5)

    NASA Astrophysics Data System (ADS)

    Makide, Y.; Kato, S.; Tominaga, T.; Takeuchi, K.

    1982-08-01

    Isotope separation of tritium by CO2 laser-induced multiphoton dissociation (MPD) of C2TF5 is reported for the first time. The MPD spectrum obtained for C2TF5 comprised a broad peak at about 940 cm-1 where C2HF5 was nearly transparent. The unimolecular dissociation of C2TF5 was induced with much lower laser fluence than that for CTF3, another working molecule we proposed for laser isotope separation of tritium. The mechanisms and kinetics of the dissociation of C2TF5 and C2HF5 were investigated under various experimental conditions: laser frequency, pulse energy, pulse duration, tritium concentration, sample pressure, buffer gas pressure and irradiation geometry. Single-step separation factors exceeding 500 were achieved with the most efficient P(20) line in 00o 10o0 transition at 944.2 cm-1.

  19. Stable isotope enrichment techniques and ORNL separation status

    NASA Astrophysics Data System (ADS)

    Tracy, J. G.; Bell, W. A.; Veach, A. M.; Caudill, H. H.; Milton, H. T.

    1987-05-01

    The isotope separation program is described, emphasizing present state-of-the-art techniques utilized to achieve specific isotopic requirements. An interesting problem addressed here is the calutron enrichment of rare-earth isotopes where small quantities of feed (< 5 g) are available, and the unresolved feed is to be recovered and recycled. Conventional ion-source units using graphite and stainless steel deteriorate in the halogenating atmosphere or are permeable to rare-earth compounds, reducing the process efficiency. An ion source has been developed using boron nitride for containing the halogenating agent and rare-earth compounds. Tests have been successfully conducted using Lu 2O 3 and the in situ chlorinating technique with CCl 4. Collectively, 166 mg of 176Lu were recovered from two runs using 2.95 and 1.10 g of 44.5% 176Lu. Process efficiency of 10.5% was achieved, and 1.2 g of the unresolved feed were recovered. Material compatibility of the boron nitride, carbon tetrachloride, and lutetium compounds has been established.

  20. 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.

  1. University Isotope Separator at Oak Ridge: The UNISOR Consortium.

    PubMed

    Hamilton, J H

    1974-09-06

    The UNISOR cooperative project, envisioned more than 3 years ago, is now successfully working. Research problems that involve a full range of experiments on nuclei far from beta stability are being investigated jointly by groups of scientists from several institutions. Some of the first work reported (16) included the identification, half-lives, and decay schemes of three new isotopes, (186)T1, (188)T1, and (116)I; the first or new decay schemes of (189)T1, (190)T1, (117)Xe, and (117)I; and the results of the perturbed gamma-gamma directional correlation work in (126)Xe. UNISOR is already stimulating international interest. A report (1) on the new research being planned with an isotope separator on-line to ORIC was presented at a Soviet Academy of Sciences meeting on nuclear structure in 1971. At an international nuclear physics conference in Munich in August 1973, Academician G. N. Flerov, director of the heavy-ion laboratory in Dubna, said the UNISOR project had inspired his laboratory to secure funds for a new, much improved isotope separator which is now installed on-line to their heavy-ion cyclotron to be used for detailed studies of nuclei far from stability. The UNISOR model for research has inspired a second such project, the Atomic Physics Consortium at Oak Ridge (APCOR). After an exploratory conference at Oak Ridge, scientists from ten institutions met in November 1973 to form an organizing committee for APCOR. As with UNISOR, the universities and the AEC will each provide a significant portion of the capital and operating costs. Heavy ions have opened up much new research in atomic physics, but such accelerator-based research represents a real "shift from traditional approaches concerning how, where, and on what time scale atomic physics experiments should be done" (17).

  2. INSTRUMENTS AND METHODS OF INVESTIGATION: Plasma isotope separation based on ion cyclotron resonance

    NASA Astrophysics Data System (ADS)

    Dolgolenko, Dmitrii A.; Muromkin, Yurii A.

    2009-04-01

    Experiments that have been conducted in the USA, France, and Russia to investigate isotopically selective ion cyclotron resonance (ICR) as a tool for plasma isotope separation are analyzed. Because this method runs into difficulties at low values of the relative isotope mass difference ΔM/M, for some elements (for gadolinium, as an example) isotope separation still remains a problem. There are ways to solve it, however, as experimental results and theoretical calculations suggest.

  3. 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.

  4. Separated isotopes: vital tools for science and medicine

    SciTech Connect

    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 as Appendixes 3 to 8. Short reports on alternate separation techniques were presented at the Workshop and are reproduced in Appendixes 9 to 11.

  5. 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.

  6. Isotope separation by selective charge conversion and field deflection

    DOEpatents

    Hickman, Robert G.

    1978-01-01

    A deuterium-tritium separation system wherein a source beam comprised of positively ionized deuterium (D.sup.+) and tritium (T.sup.+) is converted at different charge-exchange cell sections of the system to negatively ionized deuterium (D.sup.-) and tritium (T.sup.-). First, energy is added to the beam to accelerate the D.sup.+ ions to the velocity that is optimum for conversion of the D.sup.+ ions to D.sup.- ions in a charge-exchange cell. The T.sup.+ ions are accelerated at the same time, but not to the optimum velocity since they are heavier than the D.sup.+ ions. The T.sup.+ ions are, therefore, not converted to T.sup.- ions when the D.sup.+ ions are converted to D.sup.- ions. This enables effective separation of the beam by deflection of the isotopes with an electrostatic field, the D.sup.- ions being deflected in one direction and the T.sup.+ ions being deflected in the opposite direction. Next, more energy is added to the deflected beam of T.sup.+ ions to bring the T.sup.+ ions to the optimum velocity for their conversion to T.sup.- ions. In a particular use of the invention, the beams of D.sup.- and T.sup.- ions are separately further accelerated and then converted to energetic neutral particles for injection as fuel into a thermonuclear reactor. The reactor exhaust of D.sup.+ and T.sup.+ and the D.sup.+ and T.sup.+ that was not converted in the respective sections is combined with the source beam and recycled through the system to increase the efficiency of the system.

  7. Hydrogen isotope separation installation for the regeneration of tritium from gas mixtures in tritium facilities

    SciTech Connect

    Andrew, B.M.; Perevezentsev, A.N.; Selivanenko, I.L.

    1994-12-31

    The advantages and disadvantages of different methods for hydrogen isotope separation are considered in terms of their applicability for tritium regeneration in a tritium facility. Due to low inventory, simplicity of operation, flexibility, and safety the methods of separation using solid phases are preferable for tritium facility. The detail consideration of the separation processes with a solid phase reveals that highest efficiency of separation should be achieved in a counter-current separation column, which allow multiplying the thermodynamic isotopic effect. Because of difficulties of the organization of a solid phase motion in a separation column this method did not found practical application for separation of hydrogen isotopic mixtures. The main efforts of a few researches groups were devoted to improve the chromatographic separation process and equipment. The detail comparison of the separation in sectioned column with that in chromatographic as well as in cryodistillation columns show that counter-current separation in a sectioned column is more effective and has other advantages when middle throughput is required. Complete regeneration of an isotopic mixture with separation into three practically pure isotopes independently from isotopic composition of feed can be provided using two sectioned separation columns. Separation installation can operate continuously as well as periodically.

  8. 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.

  9. 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.

  10. Method for separating different isotopes in compounds by means of laser radiation

    SciTech Connect

    Meyer-Kretschmer, G.; Jetter, H.; Toennies, P.

    1984-05-29

    A method is claimed for separating isotopes of a compound having molecules in the gaseous state which comprises exciting the gas with laser radiation having a frequency capable of exciting a selected isotope thereof, interacting the excited gas with electrons having an energy sufficient to form position ions therein and separating the ionized molecules from the other molecules in the gas.

  11. Optical spectroscopy using mass-separated beams: Nuclear properties of unstable indium and tin isotopes

    NASA Astrophysics Data System (ADS)

    Kuehl, T.; Kirchner, R.; Klepper, O.; Marx, D.; Dinger, U.; Eberz, J.; Huber, G.; Lochmann, H.; Menges, R.; Ulm, G.

    1987-05-01

    Collinear fast-beam laser-spectroscopy has been used to measure the hyperfine structure and isotope shift of several indium and tin isotopes. The related experimental techniques are described, including the preparation of mass-separated beams of neutron-deficient indium and tin isotopes at the GSI on-line mass separator following fusion-evaporation reactions. The deviation of the observed dependence of the charge radii upon the neutron number from the expected behaviour is briefly discussed.

  12. Iron isotopic fractionation factor between magnetite and hydrous silicic melt

    NASA Astrophysics Data System (ADS)

    Huang, F.; Lundstrom, C. C.

    2006-12-01

    analysis of pure melt and the magnetite-melt mush with knowledge of the modes providing the ability to back out the fractionation factor. If we can prove attainment of equilibrium, this technique will bypass the difficulty of making pure separates of magnetite and melt. Fe isotopic composition of the melt and melt-magnetite layers will be measured by MC-ICP-MS.

  13. Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation

    PubMed Central

    Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

    2016-01-01

    Light isotopes separation, such as 3He/4He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as 3He/4He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high 3He/4He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application. PMID:26813491

  14. Highly Efficient Quantum Sieving in Porous Graphene-like Carbon Nitride for Light Isotopes Separation

    NASA Astrophysics Data System (ADS)

    Qu, Yuanyuan; Li, Feng; Zhou, Hongcai; Zhao, Mingwen

    2016-01-01

    Light isotopes separation, such as 3He/4He, H2/D2, H2/T2, etc., is crucial for various advanced technologies including isotope labeling, nuclear weapons, cryogenics and power generation. However, their nearly identical chemical properties made the separation challenging. The low productivity of the present isotopes separation approaches hinders the relevant applications. An efficient membrane with high performance for isotopes separation is quite appealing. Based on first-principles calculations, we theoretically demonstrated that highly efficient light isotopes separation, such as 3He/4He, can be reached in a porous graphene-like carbon nitride material via quantum sieving effect. Under moderate tensile strain, the quantum sieving of the carbon nitride membrane can be effectively tuned in a continuous way, leading to a temperature window with high 3He/4He selectivity and permeance acceptable for efficient isotopes harvest in industrial application. This mechanism also holds for separation of other light isotopes, such as H2/D2, H2/T2. Such tunable quantum sieving opens a promising avenue for light isotopes separation for industrial application.

  15. 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.

  16. Isotope separation using tuned laser and electron beam

    NASA Technical Reports Server (NTRS)

    Trajmar, Sandor (Inventor)

    1987-01-01

    The apparatus comprises means for producing an atomic beam containing the isotope of interest and other isotopes. Means are provided for producing a magnetic field traversing the path of the atomic beam of an intensity sufficient to broaden the energy domain of the various individual magnetic sublevels of the isotope of interest and having the atomic beam passing therethrough. A laser beam is produced of a frequency and polarization selected to maximize the activation of only individual magnetic sublevels of the isotope of interest with the portion of its broadened energy domain most removed from other isotopes with the stream. The laser beam is directed so as to strike the atomic beam within the magnetic field and traverse the path of the atomic beam whereby only the isotope of interest is activated by the laser beam. The apparatus further includes means for producing a collimated and high intensity beam of electrons of narrow energy distribution within the magnetic field which is aimed so as to strike the atomic beam while the atomic beam is simultaneously struck by the laser beam and at an energy level selected to ionize the activated isotope of interest but not ground state species included therewith. Deflection means are disposed in the usual manner to collect the ions.

  17. 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....

  18. 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....

  19. Gravitational separation of gases and isotopes in polar ice caps.

    PubMed

    Craig, H; Horibe, Y; Sowers, T

    1988-12-23

    Atmospheric gases trapped in polar ice at the firn to ice transition layer are enriched in heavy isotopes (nitrogen-15 and oxygen-18) and in heavy gases (O(2)/N(2) and Ar/N(2) ratios) relative to the free atmosphere. The maximum enrichments observed follow patterns predicted for gravitational equilibrium at the base of the firn layer, as calculated from the depth to the transition layer and the temperature in the firn. Gas ratios exhibit both positive and negative enrichments relative to air: the negative enrichments of heavy gases are consistent with observed artifacts of vacuum stripping of gases from fractured ice and with the relative values of molecular diameters that govern capillary transport. These two models for isotopic and elemental fractionation provide a basis for understanding the initial enrichments of carbon-13 and oxygen-18 in trapped CO(2), CH(4), and O(2) in ice cores, which must be known in order to decipher ancient atmospheric isotopic ratios.

  20. LLNL medical and industrial laser isotope separation: large volume, low cost production through advanced laser technologies

    SciTech Connect

    Comaskey, B.; Scheibner, K. F.; Shaw, M.; Wilder, J.

    1998-09-02

    The goal of this LDRD project was to demonstrate the technical and economical feasibility of applying laser isotope separation technology to the commercial enrichment (>lkg/y) of stable isotopes. A successful demonstration would well position the laboratory to make a credible case for the creation of an ongoing medical and industrial isotope production and development program at LLNL. Such a program would establish LLNL as a center for advanced medical isotope production, successfully leveraging previous LLNL Research and Development hardware, facilities, and knowledge.

  1. 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

  2. Stable isotope production in the former USSR by electromagnetic separation techniques

    NASA Astrophysics Data System (ADS)

    Kaschejev, N. A.; Polyakov, L. A.; Tunin, V. V.

    1993-09-01

    The present paper gives a brief review of the status of electromagnetic isotope separation techniques in the former USSR. It describes the basic specifications of the equipment as well as the general scheme of the production process, and considers questions relating to the chemical processing of isotopic material and analytical control techniques. Finally, a summary is given of the main separation data obtained during the last ten years, and the prospects of future development and of enhancing the economical effectiveness of isotope production are discussed.

  3. Pooled versus separate measurements of tree-ring stable isotopes.

    PubMed

    Dorado Liñán, Isabel; Gutiérrez, Emilia; Helle, Gerhard; Heinrich, Ingo; Andreu-Hayles, Laia; Planells, Octavi; Leuenberger, Markus; Bürger, Carmen; Schleser, Gerhard

    2011-05-01

    δ(13)C and δ(18)O of tree rings contain time integrated information about the environmental conditions weighted by seasonal growth dynamics and are well established as sources of palaeoclimatic and ecophysiological data. Annually resolved isotope chronologies are frequently produced by pooling dated growth rings from several trees prior to the isotopic analyses. This procedure has the advantage of saving time and resources, but precludes from defining the isotopic error or statistical uncertainty related to the inter-tree variability. Up to now only a few studies have compared isotope series from pooled tree rings with isotopic measurements from individual trees. We tested whether or not the δ(13)C and the δ(18)O chronologies derived from pooled and from individual tree rings display significant differences at two locations from the Iberian Peninsula to assess advantages and constraints of both methodologies. The comparisons along the period 1900-2003 reveal a good agreement between pooled chronologies and the two mean master series which were created by averaging raw individual values (Mean) or by generating a mass calibrated mean (MassC). In most of the cases, pooled chronologies show high synchronicity with averaged individual samples at interannual scale but some differences also show up especially when comparing δ(18)O decadal to multi-decadal variations. Moreover, differences in the first order autocorrelation among individuals may be obscured by pooling strategies. The lack of replication of pooled chronologies prevents detection of a bias due to a higher mass contribution of one sample but uncertainties associated with the analytical process itself, as sample inhomogeneity, seems to account for the observed differences.

  4. Isotopic Effect on Ion Mobility and Separation of Isotopomers by High-Field Ion Mobility Spectrometry

    SciTech Connect

    Shvartsburg, Alexandre A.; Clemmer, David E.; Smith, Richard D.

    2010-10-01

    Since early 1900-s, when vacuum techniques and ion detectors first enabled investigations of gas-phase ions, two approaches to their separation and characterization have emerged - mass spectrometry (MS) and ion mobility spectrometry (IMS).1,2 Though both exploit that distinct charged species move in electric fields differently, MS is performed in vacuum and is based only on the ion mass/charge (m/q) ratio while IMS involves sufficiently dense buffer gases and relies on ion transport properties. The first major discovery enabled by MS was the existence of isotopes by Thomson and Aston,3 and isotopic analyses have since been integral to MS. In particular, the preparative separation of U isotopes using Lawrence’s Calutron was the first industrial application of MS,4 and isotopic labeling is key to MS quantification methods. With IMS, the issue of isotopes was largely ignored as the resolving power (R) was generally too low for their separation. Here, we demonstrate that recently developed high-resolution differential IMS can separate isotopic molecular ions, including nominal isobars with different isotopic content and isotopomers. This capability may enable a new method for isotope separation in a small-scale format at ambient pressure and aid localization of labeled sites in various molecules. Perhaps most importantly, the isotopic shifts depend on the labeled atom position and thus may contain the kind of detailed structural information that is available in solution or solid state using tools such as NMR but has not generally been obtainable for gas-phase ions.

  5. National uses and needs for separated stable isotopes in physics, chemistry, and geoscience research

    NASA Astrophysics Data System (ADS)

    Zisman, M. S.

    Present uses of separated stable isotopes in the fields of physics, chemistry, and the geosciences were surveyed to identify current supply problems and to determine future needs. Demand for separated isotopes remains strong, with 220 different nuclides having been used in the past three years. The largest needs, in terms of both quantity and variety of isotopes, are found in nuclear physics research. Current problems include a lack of availability of many nuclides, unsatisfactory enrichment of rare species, and prohibitively high costs for certain important isotopes. Demand for separated isotopes is expected to remain roughly at present levels, although a shift toward more requests for highly enriched rare isotopes is predicted. Use of neutron rich nuclides below A = 100 for producing exotic ion beams at various accelerators and use of transition metal nuclei for nuclear magnetic resonance spectroscopy are expected to expand. An increase in the need for calibration standards for techniques of radiological dating, such as Sm/Nd and Lu/Hf is predicted, but in relatively small quantities. Most members of the research community would be willing to pay considerably more than they do now to maintain adequate supplies of stable isotopes.

  6. National uses and needs for separated stable isotopes in physics, chemistry, and geoscience research

    SciTech Connect

    Zisman, M.S.

    1982-01-01

    Present uses of separated stable isotopes in the fields of physics, chemistry, and the geosciences have been surveyed to identify current supply problems and to determine future needs. Demand for separated isotopes remains strong, with 220 different nuclides having been used in the past three years. The largest needs, in terms of both quantity and variety of isotopes, are found in nuclear physics research. Current problems include a lack of availability of many nuclides, unsatisfactory enrichment of rare species, and prohibitively high costs for certain important isotopes. It is expected that demands for separated isotopes will remain roughly at present levels, although there will be a shift toward more requests for highly enriched rare isotopes. Significantly greater use will be made of neutron-rich nuclides below A = 100 for producing exotic ion beams at various accelerators. Use of transition metal nuclei for nuclear magnetic resonance spectroscopy will expand. In addition, calibration standards will be required for the newer techniques of radiological dating, such as the Sm/Nd and Lu/Hf methods, but in relatively small quantities. Most members of the research community would be willing to pay considerably more than they do now to maintain adequate supplies of stable isotopes.

  7. Electromagnetic separation of stable isotopes at the Institute of Atomic Energy, Academia Sinica

    NASA Astrophysics Data System (ADS)

    Ming-da, Hua; Gong-pan, Li; Shi-jun, Su; Nai-feng, Mao; Hung-yung, Lu

    1981-07-01

    For almost 20 years the Institute of Atomic Energy, Academia Sinica has been separating stable isotopes of the elements by electromagnetic separators and supplying these materials to research work in many fields of our country. In this article we shall attempt to outline the growth of the effort and describe the present situation.

  8. Nested reactor chamber and operation for Hg-196 isotope separation process

    DOEpatents

    Grossman, M.W.

    1991-10-08

    The present invention is directed to an apparatus for use in [sup 196]Hg separation and its method of operation. Specifically, the present invention is directed to a nested reactor chamber useful for [sup 196]Hg isotope separation reactions avoiding the photon starved condition commonly encountered in coaxial reactor systems. 6 figures.

  9. Nested reactor chamber and operation for Hg-196 isotope separation process

    DOEpatents

    Grossman, Mark W.

    1991-01-01

    The present invention is directed to an apparatus for use in .sup.196 Hg separation and its method of operation. Specifically, the present invention is directed to a nested reactor chamber useful for .sup.196 Hg isotope separation reactions avoiding the photon starved condition commonly encountered in coaxial reactor systems.

  10. Separation of selected stable isotopes by liquid-phase thermal diffusion and by chemical exchange

    NASA Astrophysics Data System (ADS)

    Rutherford, W. M.; Jepson, B. E.; Michaels, E. D.

    Useful applications of enriched stable nuclides are unduly restricted by high cost and limited availability. Recent research on liquid phase thermal diffusion (LTD) has resulted in practical processes for separating S34, CL35, and CL37 in significant quantities (100 to 500 g/yr) at costs much lower than those associated with the electromagnetic (Calutron) process. The separation of the isotopes of bromine by LTD is now in progress and BR79 is being produced in relatively simple equivalent at a rate on the order of 0.5 g/day. The results of recent measurements show that the isotopes of Zn can be separated by LTD of zinc alkyls. The isotopes of calcium can be separated by LTD and by chemical exchange. The LTD process is based on the use of aqueous Ca(NO3)2 as a working fluid.

  11. Isotopic effect on ion mobility and separation of isotopomers by high-field ion mobility spectrometry.

    PubMed

    Shvartsburg, Alexandre A; Clemmer, David E; Smith, Richard D

    2010-10-01

    Distinguishing and separating isotopic molecular variants is important across many scientific fields. However, discerning such variants, especially those producing no net mass difference, has been challenging. For example, single-stage mass spectrometry is broadly employed to analyze isotopes but is blind to isotopic isomers (isotopomers) and, except at very high resolution, species of the same nominal mass (isobars). Here, we report separation of isotopic ions, including isotopomers and isobars, using ion mobility spectrometry (IMS), specifically, the field asymmetric waveform IMS (FAIMS). The effect is not based on the different reduced masses of ion-gas molecule pairs previously theorized to cause isotopic separations in conventional IMS, but appears related to the details of energetic ion-molecule collisions in strong electric fields. The observed separation qualitatively depends on the gas composition and may be improved using gas mixtures. Isotopic shifts depend on the position of the labeled site, which allows its localization and contains information about the ion geometry, potentially enabling a new approach to molecular structure characterization.

  12. Anisotropic alpha emission from on-line separated isotopes

    SciTech Connect

    Wouters, J.; Vandeplassche, D.; van Walle, E.; Severijns, N.; Vanneste, L.

    1986-05-05

    A systematic on-line nuclear-orientation study of heavy isotopes using anisotropic ..cap alpha.. emission is reported for the first time. The anisotrophies recorded for /sup 199/At, /sup 201/At, and /sup 203/At are remarkably pronounced and strongly varying. At lower neutron number the ..cap alpha.. particles are more preferentially emitted perpendicularly to the nuclear-spin direction. This may be interpreted in terms of the high sensitivity of the ..cap alpha..-emission probability to changes in the nuclear shape.

  13. Photo-induced cataphoretic isotope separation. Final report, June 15, 1976-June 15, 1981

    SciTech Connect

    Carruthers, J A

    1981-03-01

    The original studies were undertaken to study the feasibility of radiation-induced cataphoretic separation. This part of the work is concerned with laser-induced cataphoretic separation in neon using a He-Ne 6328A laser. The basic concept of radiation-induced caphoretic isotope separation is based on the preferential excitation of one isotope with the result that one isotope is more readily ionized, and relatively more of its ions move toward the cathode in the dc discharge. For the later part of the work a second radiation source was added, a helical Ne/sup 20/ radiation lamp. Radiation-induced cataphoretic isotope separation has not been observed. Selective excitation has been achieved by both the He-Ne/sup 20/ 6328A laser and the Ne/sup 20/ helical radiation lamp in spite of the fact that the isotope shift is comprable with Doppler-broadened linewidths. Collisional excitation exchange between the Ne/sup 20/ and Ne/sup 22/ atoms does not appear to be a problem for the neon partial pressure range involved. The population of the 3S/sub 2/ and 2p/sub 4/ laser levels (6328A) are apparently too low to offer reasonable expectation of inducing observable cataphoretic isotope separation by means of the 6328A laser radiation, even with the high detection sensitivity of the scanning Fabry-Perot spectrometer sytem. The use of the additional radiation source in the form of a helical Ne/sup 20/ radiation lamp has not improved the effectiveness of the laser 6328A laser. It has become clear from these experiments, however, that for isotope separation in neon it is well to concentrate on using radiation sources that interact mainly with the ls population.

  14. Separation and Analysis of Boron Isotope in High Plant by Thermal Ionization Mass Spectrometry

    PubMed Central

    Xu, Qingcai; Dong, Yuliang; Zhu, Huayu; Sun, Aide

    2015-01-01

    Knowledge of boron and its isotope in plants is useful to better understand the transposition and translocation of boron within plant, the geochemical behavior in the interface between soil and plant, and the biogeochemical cycle of boron. It is critical to develop a useful method to separate boron from the plant for the geochemical application of boron and its isotope. A method was developed for the extraction of boron in plant sample, whose isotope was determined by thermal ionization mass spectrometry. The results indicated that this method of dry ashing coupled with two-step ion-exchange chromatography is powerful for the separation of boron in plant sample with large amounts of organic matters completely. The ratios of boron isotope composition in those plant tissue samples ranged from −19.45‰ to +28.13‰ (total range: 47.58‰) with a mean value of 2.61 ± 11.76‰ SD. The stem and root isotopic compositions were lower than those in flower and leaf. The molecular mechanism of boron isotope may be responsible for the observed variation of boron isotopic composition and are considered as a useful tool for the better understanding of boron cycling process in the environment and for the signature of living systems. PMID:26819618

  15. Isotope separation and advanced manufacturing technology. Volume 2, No. 2, Semiannual report, April--September 1993

    SciTech Connect

    Kan, Tehmanu; Carpenter, J.

    1993-12-31

    This is the second issue of a semiannual report for the Isotope Separation and Advanced Manufacturing (ISAM) Technology Program at Lawrence Livermore National Laboratory. Primary objectives of the ISAM Program include: the Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) process, and advanced manufacturing technologies which include industrial laser materials processing and new manufacturing technologies for uranium, plutonium, and other strategically important materials in support of DOE and other national applications. Topics included in this issue are: production plant product system conceptual design, development and operation of a solid-state switch for thyratron replacement, high-performance optical components for high average power laser systems, use of diode laser absorption spectroscopy for control of uranium vaporization rates, a two-dimensional time dependent hydrodynamical ion extraction model, and design of a formaldehyde photodissociation process for carbon and oxygen isotope separation.

  16. Electromagnetic Separation of Isotopes at Oak Ridge: An informal account of history, techniques, and accomplishments.

    PubMed

    Love, L O

    1973-10-26

    In 1960 I attended a European conference on isotope separation, after which I visited the Niels Bohr Institute in Copenhagen. A staff member there ventured the opinion that the separation of isotopes will be first on the list of important contributions to the peaceful uses of the atom when the Atomic Energy Commission's memoirs are written in the year 2000. In 1968 the AEC Division of Research contracted with the National Research Council of the National Academy of Sciences to conduct a review of the AEC program for the separation of stable isotopes by electromagnetic and thermal diffusion methods. This ad hoc panel comprised seven scientists from the fields of chemistry, classical physics, geochemistry, geophysics, medicine, and physics. In their final report on national uses and needs for separated stable isotopes (9), they referred to the store of separated isotopes as a "real national asset that attains increasing value as science and technology develop" and recommended "continuation of the program as a national resource of great value to the United States." Later, in a discussion of this report with A. M. Weinberg, J. Koch, himself a pioneer in electromagnetic isotope separation and member of the Danish Atomic Energy Program, said he would correct the statement that the Oak Ridge electromagnetic facility is a "national asset" to read "international asset." From my narrow viewpoint after an extended and complete engrossment with this program for so many years, it is gratifying to learn that such men as those mentioned above share my belief that the work has indeed been worthwhile.

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

    SciTech Connect

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

    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 and 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)

  18. A Model of Isotope Separation in Cells at the Early Stages of Evolution.

    PubMed

    Melkikh, A V; Bokunyaeva, A O

    2016-03-01

    The separation of the isotopes of certain ions can serve as an important criterion for the presence of life in the early stages of its evolution. A model of the separation of isotopes during their transport through the cell membrane is constructed. The dependence of the selection coefficient on various parameters is found. In particular, it is shown that the maximum efficiency of the transport of ions corresponds to the minimum enrichment coefficient. At the maximum enrichment, the efficiency of the transport system approaches ½. Calculated enrichment coefficients are compared with experimentally obtained values for different types of cells, and the comparison shows a qualitative agreement between these quantities.

  19. Multi-purpose hydrogen isotopes separation plant design

    SciTech Connect

    Boniface, H.A.; Gnanapragasam, N.V.; Ryland, D.K.; Suppiah, S.; Castillo, I.

    2015-03-15

    There is a potential interest at AECL's Chalk River Laboratories to remove tritium from moderately tritiated light water and to reclaim tritiated, downgraded heavy water. With only a few limitations, a single CECE (Combined Electrolysis and Catalytic Exchange) process configuration can be designed to remove tritium from heavy water or light water and upgrade heavy water. Such a design would have some restrictions on the nature of the feed-stock and tritium product, but could produce essentially tritium-free light or heavy water that is chemically pure. The extracted tritium is produced as a small quantity of tritiated heavy water. The overall plant capacity is fixed by the total amount of electrolysis and volume of catalyst. In this proposal, with 60 kA of electrolysis a throughput of 15 kg*h{sup -1} light water for detritiation, about 4 kg*h{sup -1} of heavy water for detritiation and about 27 kg*h{sup -1} of 98% heavy water for upgrading can be processed. Such a plant requires about 1,000 liters of AECL isotope exchange catalyst. The general design features and details of this multi-purpose CECE process are described in this paper, based on some practical choices of design criteria. In addition, we outline the small differences that must be accommodated and some compromises that must be made to make the plant capable of such flexible operation. (authors)

  20. Anisotropic. cap alpha. -emission of on-line separated isotopes

    SciTech Connect

    Wouters, J.; Vandeplassche, D.; van Walle, E.; Severijns, N.; Van Haverbeke, J.; Vanneste, L.

    1987-12-10

    The technical realization of particle detection at very low temperatures (4K) has made it possible to study for the first time the anisotropic ..cap alpha..-decay of oriented nuclei which have been produced, separated and implanted on line. The measured ..cap alpha..-angular distributions reveal surprising new results on nuclear aspects as well as in solid state physics. The nuclear structure information from these data questions the older ..cap alpha..-decay theoretical interpretation and urges for a reaxamination of the earliest work on anisotropic ..cap alpha..-decay.

  1. Investigation related to hydrogen isotopes separation by cryogenic distillation

    SciTech Connect

    Bornea, A.; Zamfirache, M.; Stefanescu, I.; Preda, A.; Balteanu, O.; Stefan, I.

    2008-07-15

    Research conducted in the last fifty years has shown that one of the most efficient techniques of removing tritium from the heavy water used as moderator and coolant in CANDU reactors (as that operated at Cernavoda (Romania)) is hydrogen cryogenic distillation. Designing and implementing the concept of cryogenic distillation columns require experiments to be conducted as well as computer simulations. Particularly, computer simulations are of great importance when designing and evaluating the performances of a column or a series of columns. Experimental data collected from laboratory work will be used as input for computer simulations run at larger scale (for The Pilot Plant for Tritium and Deuterium Separation) in order to increase the confidence in the simulated results. Studies carried out were focused on the following: - Quantitative analyses of important parameters such as the number of theoretical plates, inlet area, reflux flow, flow-rates extraction, working pressure, etc. - Columns connected in series in such a way to fulfil the separation requirements. Experiments were carried out on a laboratory-scale installation to investigate the performance of contact elements with continuous packing. The packing was manufactured in our institute. (authors)

  2. 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.

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

    SciTech Connect

    Watkins, J.M.; DePaolo, D.J.; Ryerson, F.J.; Peterson, B.

    2011-03-01

    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{sub 2}Si{sub 2}O{sub 8}; denoted AN), albite (NaAlSi{sub 3}O{sub 8}; denoted AB), and diopside (CaMgSi{sub 2}O{sub 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{sub Ca}/D{sub Si} ~ 20 and the efficiency of isotope separation for Ca is much greater than in natural liquid experiments where D{sub Ca}/D{sub Si} ~ 1. In the AB–DI experiment, D{sub Ca}/D{sub 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{sub Mg}/D{sub 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{sub Ca}) to the diffusivity of silicon (D{sub 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{sub cation

  4. A Low Temperature Distillation System for Separating Mixtures of Protium, Deuterium, and Tritium Isotopes

    SciTech Connect

    Embury, Michael, C.; Watkins, Reed A.; Hinckley, Richard; Post, Jr., Arthur H.

    1985-04-30

    A low temperature (24 K) distillation system for separating mixtures of hydrogen isotopes has been designed, fabricated, and delivered for use as the main component of the Hydrogen Isotope Separation System (HISS) at Mound. The HISS will handle feed mixtures of all six isotopic species of hydrogen (H2, HD, HT, D2, DT, T2) and will enrich the tritium while producing a stackable raffinate. Arther D. Little, Inc. (ADL) was the prime contractor for the distillation system. The design and fabrication techniques used for the HISS distillation system are similar to those used for previous stills which were also designed and built by ADL. The distillation system was tested with mixtures of protium and deuterium at the ADL shop. This system, as well as the feed, product, and raffinate handling systems are presently being installed at Mound where integrated testing is scheduled next calendar year.

  5. Packed bed reactor for photochemical .sup.196 Hg isotope separation

    DOEpatents

    Grossman, Mark W.; Speer, Richard

    1992-01-01

    Straight tubes and randomly oriented pieces of tubing having been employed in a photochemical mercury enrichment reactor and have been found to improve the enrichment factor (E) and utilization (U) compared to a non-packed reactor. One preferred embodiment of this system uses a moving bed (via gravity) for random packing.

  6. Installations for separation of hydrogen isotopes by the method of chemical isotopic exchange in the `water-hydrogen` system

    SciTech Connect

    Andreev, B.M.; Sakharovsky, Y.A.; Rozenkevich, M.B.; Magomedbekov, E.P.; Park, Y.S.; Uborskiy, V.V.; Trenin, V.D.; Alekseev, I.A.; Fedorchenko, O.A.; Karpov, S.P.; Konoplev, K.A.

    1995-10-01

    The paper presents the results of more than a year of running a pilot setup for separation of hydrogen isotopes using catalytic isotopic exchange between hydrogen and liquid water. The setup is 5 m high, has the inner diameter of 28 mm, and is equipped with upper and lower reflux devices. The experimental values of HETP vary from 15 cm at T=333 K to 38 cm at T=293 K. The setup is capable of upgrading diluted heavy water with 85-90% deuterium content up to [D{sub 2}O] > 99.95 at.%, yielding daily 4 kg of the product. We also report on the progress in constructing a similar setup for eliminating tritium and an industrial setup, for which the one reported is a prototype. 10 refs., 1 fig., 3 tabs.

  7. Experimental Confirmation of Isotope Fractionation in Thiomolybdates Using Ion Chromatographic Separation and Detection by Multicollector ICPMS.

    PubMed

    Kerl, Carolin F; Lohmayer, Regina; Bura-Nakić, Elvira; Vance, Derek; Planer-Friedrich, Britta

    2017-03-07

    Molybdenum (98)Mo/(95)Mo isotope ratios are a sediment paleo proxy for the redox state of the ancient ocean. Under sulfidic conditions, no fractionation between seawater and sediment should be observed if molybdate (MoO4(2-)) is quantitatively transformed to tetrathiomolybdate (MoS4(2-)) and precipitated. However, quantum mechanical calculations previously suggested that incomplete sulfidation could be associated with substantial fractionation. To experimentally confirm isotope fractionation in thiomolybdates, a new approach for determination of isotope ratios of individual thiomolybdate species was developed that uses chromatography (HPLC-UV) to separate individual thiomolybdates, collecting each peak and analyzing isotope ratios with multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Using commercially available MoO4(2-) and MoS4(2-) standards, the method was evaluated and excellent reproducibility and accuracy were obtained. For species with longer retention times, complete chromatographic peaks had to be collected to avoid isotope fractionation within peaks. Isotope fractionation during formation of thiomolybdates could be experimentally proven for the first time in the reaction of MoO4(2-) with 20-fold or 50-fold excess of sulfide. The previously calculated isotope fractionation for MoS4(2-) was confirmed, and the result for MoO2S2(2-) was in the predicted range. Isotopic fractionation during MoS4(2-) transformation with pressurized air was dominated by kinetic fractionation. Further optimization and online-coupling of the HPLC-MC-ICPMS approach for determination of low concentrations in natural samples will greatly help to obtain more accurate species-selective isotope information.

  8. TCAP HYDROGEN ISOTOPE SEPARATION USING PALLADIUM AND INVERSE COLUMNS

    SciTech Connect

    Heung, L.; Sessions, H.; Xiao, S.

    2010-08-31

    The Thermal Cycling Absorption Process (TCAP) was further studied with a new configuration. Previous configuration used a palladium packed column and a plug flow reverser (PFR). This new configuration uses an inverse column to replace the PFR. The goal was to further improve performance. Both configurations were experimentally tested. The results showed that the new configuration increased the throughput by a factor of more than 2.

  9. The effect of small scale variablity in isotopic composition of precipitation on hydrograph separation results

    NASA Astrophysics Data System (ADS)

    Fischer, Benjamin; van Meerveld, Ilja; Seibert, Jan

    2016-04-01

    Understanding runoff processes is important for predictions of streamflow quantity and quality. The two-component isotope hydrograph separation (IHS) method is a valuable tool to study how catchments transform rainfall into runoff. IHS allows the stormflow hydrograph to be separated into rainfall (event water) and water that was stored in the catchment before the event (pre-event water). To be able to perform an IHS, water samples of baseflow (pre-event water) and stormflow are collected at the stream outlet. Rainfall is usually collected at one location by hand as an event total or sampled sequentially during the event. It is usually assumed that the spatial variability in rainfall and the isotopic composition of rainfall are negligible for small (<10km2) catchments. However, different studies have shown that precipitation can vary within short distances. Subsequently it remains unclear how the spatio-temproal variability of rainfall and the stable isotope composition of rainfall affect the results of an IHS. In this study, we investigated the effects of the spatio-temporal variability in the isotopic composition of rainfall across a small headwater catchment in Switzerland. Rainfall was measured at eight locations and three streams (catchment area of 0.15, 0.23, and 0.7 km2). The isotopic composition of rainfall and streamflow were sampled for 10 different rain events (P: 5 mm intervals, Q: 12 to 51 samples per events). This dataset was used to perform a two-component isotope hydrograph separation. The results show that for some events the spatial variability in total rainfall, mean and maximum rainfall intensity and stable isotope composition of rainfall was high. There was no relation between the stable isotope composition of rainfall and the rainfall sum, rainfall intensity or altitude. The spatial variability of the isotopic composition of rainfall was for 4 out of the 10 events as large as the temporal variability in the isotopic composition. Different

  10. 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

  11. The iron isotope composition of enstatite meteorites: Implications for their origin and the metal/sulfide Fe isotopic fractionation factor

    NASA Astrophysics Data System (ADS)

    Wang, Kun; Savage, Paul S.; Moynier, Frédéric

    2014-10-01

    due to intensive impact-induced shearing stress, or the ultimate destruction of the Shallowater parent body. Analysis of separated enstatite meteorite mineral phases show that the magnetic phase (Fe metal) is systematically enriched in the heavier Fe isotopes when compared to non-magnetic phases (Fe hosted in troilite), which agrees with previous experimental observations and theoretical calculations. The difference between magnetic and non-magnetic phases from enstatite achondrites provides an equilibrium metal-sulfide Fe isotopic fractionation factor of Δ56Femetal-troilite = δ56Femetal - δ56Fetroilite of 0.129 ± 0.060‰ (2 SE) at 1060 ± 80 K, which confirms the predictions of previous theoretical calculations.

  12. 10 CFR Appendix N to Part 110 - Illustrative List of Lithium Isotope Separation Facilities, Plants and Equipment Under NRC's...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ..., Plants and Equipment Under NRC's Export Licensing Authority N Appendix N to Part 110 Energy NUCLEAR... 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....

  13. 10 CFR Appendix N to Part 110 - Illustrative List of Lithium Isotope Separation Facilities, Plants and Equipment Under NRC's...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ..., Plants and Equipment Under NRC's Export Licensing Authority N Appendix N to Part 110 Energy NUCLEAR... 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....

  14. 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

    ..., Plants and Equipment Under NRC's Export Licensing Authority N Appendix N to Part 110 Energy NUCLEAR... 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....

  15. 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.

  16. IRiS—Exploring new frontiers in neutron-rich isotopes of the heaviest elements with a new Inelastic Reaction Isotope Separator

    NASA Astrophysics Data System (ADS)

    Dvorak, J.; Block, M.; Düllmann, Ch. E.; Heinz, S.; Herzberg, R.-D.; Schädel, M.

    2011-10-01

    A dedicated Inelastic Reaction Isotope Separator (IRiS) for multi-nucleon transfer products will be designed and installed at GSI. Research at IRiS will focus on the investigation of new neutron-rich isotopes of the heaviest elements, study of which will advance various research fields, such as nuclear chemistry, nuclear and atomic physics, as well as nuclear astrophysics. The scientific motivation for this project and the alternative design options for the separator and its main components are discussed.

  17. Implications of Plutonium isotopic separation on closed fuel cycles and repository design

    SciTech Connect

    Forsberg, C.

    2013-07-01

    Advances in laser enrichment may enable relatively low-cost plutonium isotopic separation. This would have large impacts on LWR closed fuel cycles and waste management. If Pu-240 is removed before recycling plutonium as mixed oxide (MOX) fuel, it would dramatically reduce the buildup of higher plutonium isotopes, Americium, and Curium. Pu-240 is a fertile material and thus can be replaced by U-238. Eliminating the higher plutonium isotopes in MOX fuel increases the Doppler feedback, simplifies reactor control, and allows infinite recycle of MOX plutonium in LWRs. Eliminating fertile Pu-240 and Pu-242 reduces the plutonium content in MOX fuel and simplifies fabrication. Reducing production of Pu-241 reduces production of Am-241 - the primary heat generator in spent nuclear fuels after several decades. Reducing heat generating Am-241 would reduce repository cost and waste toxicity. Avoiding Am- 241 avoids its decay product Np-237, a nuclide that partly controls long-term oxidizing repository performance. Most of these benefits also apply to LWR plutonium recycled into fast reactors. There are benefits for plutonium isotopic separation in fast reactor fuel cycles (particularly removal of Pu-242) but the benefits are less. (author)

  18. Isotopic incorporation rates and discrimination factors in mantis shrimp crustaceans.

    PubMed

    deVries, Maya S; Del Rio, Carlos Martínez; Tunstall, Tate S; Dawson, Todd E

    2015-01-01

    Stable isotope analysis has provided insights into the trophic ecology of a wide diversity of animals. Knowledge about isotopic incorporation rates and isotopic discrimination between the consumer and its diet for different tissue types is essential for interpreting stable isotope data, but these parameters remain understudied in many animal taxa and particularly in aquatic invertebrates. We performed a 292-day diet shift experiment on 92 individuals of the predatory mantis shrimp, Neogonodactylus bredini, to quantify carbon and nitrogen incorporation rates and isotope discrimination factors in muscle and hemolymph tissues. Average isotopic discrimination factors between mantis shrimp muscle and the new diet were 3.0 ± 0.6 ‰ and 0.9 ± 0.3 ‰ for carbon and nitrogen, respectively, which is contrary to what is seen in many other animals (e.g. C and N discrimination is generally 0-1 ‰ and 3-4 ‰, respectively). Surprisingly, the average residence time of nitrogen in hemolymph (28.9 ± 8.3 days) was over 8 times longer than that of carbon (3.4 ± 1.4 days). In muscle, the average residence times of carbon and nitrogen were of the same magnitude (89.3 ± 44.4 and 72.8 ± 18.8 days, respectively). We compared the mantis shrimps' incorporation rates, along with rates from four other invertebrate taxa from the literature, to those predicted by an allometric equation relating carbon incorporation rate to body mass that was developed for teleost fishes and sharks. The rate of carbon incorporation into muscle was consistent with rates predicted by this equation. Our findings provide new insight into isotopic discrimination factors and incorporation rates in invertebrates with the former showing a different trend than what is commonly observed in other animals.

  19. Isotopic Incorporation Rates and Discrimination Factors in Mantis Shrimp Crustaceans

    PubMed Central

    deVries, Maya S.; del Rio, Carlos Martínez; Tunstall, Tate S.; Dawson, Todd E.

    2015-01-01

    Stable isotope analysis has provided insights into the trophic ecology of a wide diversity of animals. Knowledge about isotopic incorporation rates and isotopic discrimination between the consumer and its diet for different tissue types is essential for interpreting stable isotope data, but these parameters remain understudied in many animal taxa and particularly in aquatic invertebrates. We performed a 292-day diet shift experiment on 92 individuals of the predatory mantis shrimp, Neogonodactylus bredini, to quantify carbon and nitrogen incorporation rates and isotope discrimination factors in muscle and hemolymph tissues. Average isotopic discrimination factors between mantis shrimp muscle and the new diet were 3.0 ± 0.6 ‰ and 0.9 ± 0.3 ‰ for carbon and nitrogen, respectively, which is contrary to what is seen in many other animals (e.g. C and N discrimination is generally 0–1 ‰ and 3–4 ‰, respectively). Surprisingly, the average residence time of nitrogen in hemolymph (28.9 ± 8.3 days) was over 8 times longer than that of carbon (3.4 ± 1.4 days). In muscle, the average residence times of carbon and nitrogen were of the same magnitude (89.3 ± 44.4 and 72.8 ± 18.8 days, respectively). We compared the mantis shrimps’ incorporation rates, along with rates from four other invertebrate taxa from the literature, to those predicted by an allometric equation relating carbon incorporation rate to body mass that was developed for teleost fishes and sharks. The rate of carbon incorporation into muscle was consistent with rates predicted by this equation. Our findings provide new insight into isotopic discrimination factors and incorporation rates in invertebrates with the former showing a different trend than what is commonly observed in other animals. PMID:25835953

  20. 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.

  1. Unbiased isotope equilibrium factors from partial isotope exchange experiments in 3-exchange site systems

    NASA Astrophysics Data System (ADS)

    Agrinier, Pierre; Javoy, Marc

    2016-09-01

    Two methods are available in order to evaluate the equilibrium isotope fractionation factors between exchange sites or phases from partial isotope exchange experiments. The first one developed by Northrop and Clayton (1966) is designed for isotope exchanges between two exchange sites (hereafter, the N&C method), the second one from Zheng et al. (1994) is a refinement of the first one to account for a third isotope exchanging site (hereafter, the Z method). In this paper, we use a simple model of isotope kinetic exchange for a 3-exchange site system (such as hydroxysilicates where oxygen occurs as OH and non-OH groups like in muscovite, chlorite, serpentine, or water or calcite) to explore the behavior of the N&C and Z methods. We show that these two methods lead to significant biases that cannot be detected with the usual graphical tests proposed by the authors. Our model shows that biases originate because isotopes are fractionated between all these exchanging sites. Actually, we point out that the variable mobility (or exchangeability) of isotopes in and between the exchange sites only controls the amplitude of the bias, but is not essential to the production of this bias as previously suggested. Setting a priori two of the three exchange sites at isotopic equilibrium remove the bias and thus is required for future partial exchange experiments to produce accurate and unbiased extrapolated equilibrium fractionation factors. Our modeling applied to published partial oxygen isotope exchange experiments for 3-exchange site systems (the muscovite-calcite (Chacko et al., 1996), the chlorite-water (Cole and Ripley, 1998) and the serpentine-water (Saccocia et al., 2009)) shows that the extrapolated equilibrium fractionation factors (reported as 1000 ln(α)) using either the N&C or the Z methods lead to bias that may reach several δ per mil in a few cases. These problematic cases, may be because experiments were conducted at low temperature and did not reach high

  2. Separation of calcium-48 isotope by crown ether chromatography using ethanol/hydrochloric acid mixed solvent.

    PubMed

    Okumura, Shin; Umehara, Saori; Fujii, Yasuhiko; Nomura, Masao; Kaneshiki, Toshitaka; Ozawa, Masaki; Kishimoto, Tadafumi

    2015-10-09

    Benzo-18-crown-6 ether resin embedded in porous silica beads was synthesized and used as the packing material for chromatographic separation of (48)Ca isotope. The aim of the present work is to develop efficient isotope enrichment process for double β decay nuclide (48)Ca. To this end, ethanol/HCl mixed solvent was selected as the medium for the chromatographic separation. Adsorption of calcium on the resin was studied at different HCl concentrations and different ethanol mixing ratios in batch-wise experiments. A very interesting phenomenon was observed; Ca adsorption is controlled not by the overall HCl concentration of the mixed solvent, but by the initial concentration of added HCl solution. Calcium break-through chromatography experiments were conducted by using 75v/v% ethanol/25v/v% 8M HCl mixed solvent at different flow rates. The isotope separation coefficient between (48)Ca and (40)Ca was determined as 3.8×10(-3), which is larger than that of pure HCl solution system. Discussion is extended to the chromatographic HETP, height equivalent to a theoretical plate.

  3. 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

  4. Extracting Spectroscopic Factors of Argon Isotopes from Transfer Reactions

    NASA Astrophysics Data System (ADS)

    Manfredi, Juan; Lee, J.; Tsang, M. B.; Lynch, W. G.; Barney, J.; Estee, J.; Sweany, S.; Brown, K. W.; Cerizza, G.; Anderson, C.; Setiawan, H.; Loelius, C.; Xu, Z.; Rogers, A. M.; Pruitt, C.; Sobotka, L. G.; Elson, J. M.; Langer, C.; Chajecki, Z.; Chen, G.; Jones, K. L.; Smith, K.; Xiao, Z.; Li, Z.; Winkelbauer, J. R.

    2017-01-01

    A spectroscopic factor (SF) quantifies the single particle occupancy of a given state in a nucleus. For the argon isotopes, there is a discrepancy of the SF between studies that use transfer reactions and knockout reactions. Understanding the SFs of these isotopes, and in particular how the SF changes across the isotopic chain, is important for understanding how single particle structure changes with neutron number. The transfer reactions 34Ar(p,d) and 46Ar(p,d) were measured at the National Superconducting Cyclotron Laboratory (NSCL) using the same beam energy (70 MeV/u) as from the previous knockout measurement. Spectroscopic factors were extracted from measured angular distributions via ADWA calculations. Preliminary findings will be presented. The National Superconducting Cyclotron Laboratory is supported by the NSF (PHY 1102511), and Juan Manfredi is supported by the DOE NNSA Stewardship Science Graduate Fellowship.

  5. 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.

  6. DEMONSTRATION OF THE NEXT-GENERATION TCAP HYDROGEN ISOTOPE SEPARATION PROCESS

    SciTech Connect

    Heung, L; Henry Sessions, H; Steve Xiao, S; Heather Mentzer, H

    2009-01-09

    The first generation of TCAP hydrogen isotope separation process has been in service for tritium separation at the Savannah River Site since 1994. To prepare for replacement, a next-generation TCAP process has been developed. This new process simplifies the column design and reduces the equipment requirements of the thermal cycling system. An experimental twelve-meter column was fabricated and installed in the laboratory to demonstrate its performance. This new design and its initial test results were presented at the 8th International Conference on Tritium Science and Technology and published in the proceedings. We have since completed the startup and demonstration the separation of protium and deuterium in the experimental unit. The unit has been operated for more than 200 cycles. A feed of 25% deuterium in protium was separated into two streams each better than 99.7% purity.

  7. 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.

  8. Separation Of Uranium And Plutonium Isotopes For Measurement By Multi Collector Inductively Coupled Plasma Mass Spectroscopy

    SciTech Connect

    Martinelli, R E; Hamilton, T F; Williams, R W; Kehl, S R

    2009-03-29

    Uranium (U) and plutonium (Pu) isotopes in coral soils, contaminated by nuclear weapons testing in the northern Marshall Islands, were isolated by ion-exchange chromatography and analyzed by mass spectrometry. The soil samples were spiked with {sup 233}U and {sup 242}Pu tracers, dissolved in minerals acids, and U and Pu isotopes isolated and purified on commercially available ion-exchange columns. The ion-exchange technique employed a TEVA{reg_sign} column coupled to a UTEVA{reg_sign} column. U and Pu isotope fractions were then further isolated using separate elution schemes, and the purified fractions containing U and Pu isotopes analyzed sequentially using multi-collector inductively coupled plasma mass spectrometer (MCICP-MS). High precision measurements of {sup 234}U/{sup 235}U, {sup 238}U/{sup 235}U, {sup 236}U/{sup 235}U, and {sup 240}Pu/{sup 239}Pu in soil samples were attained using the described methodology and instrumentation, and provide a basis for conducting more detailed assessments of the behavior and transfer of uranium and plutonium in the environment.

  9. 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.

  10. Theoretical prediction for several important equilibrium Ge isotope fractionation factors

    NASA Astrophysics Data System (ADS)

    Tang, M.; Li, X.; Liu, Y.

    2008-12-01

    As a newly emerging field, the stable isotope geochemistry of germanium (Ge) needs basic equilibrium fractionation factors to explore its unknown world. In this study, the Ge isotope fractionations between systems including the aqueous Ge(OH)4 and GeO(OH)3- which are the dominant Ge species in seawater, the Ge-bearing organic complexes (e.g. Ge-catechol, Ge-oxalic acid and Ge-citric acid), the quartz- (or opal- ), albite-, K-feldspar- and olivine- like mineral structures are studied. It is the first time that some geologically important equilibrium Ge isotope fractionation factors are reported. Surprisingly, up to 5 per mil large isotopic fractionations between these Ge isotope systems are found at 25 degree. These results suggest a potentially broad application for the Ge isotope geochemistry. Our theoretical calculations are based on the Urey model (or Bigeleisen-Mayer equation) and high level quantum chemistry calculations. The B3LYP/6-311+G(d,p) level quantum chemistry method and the explicit solvent model ("water droplet" method) are used. Many different conformers are also used for the aqueous complexes in order to reduce the possible errors coming from the differences of configurations in solution. The accuracy of our calculation of the Ge isotopic fractionations is estimated about 0.2 per mil. Our results show quartz-like or opal-like structure can enrich most heavy Ge isotopes. Relative to quartz (or opal), some Ge isotopic fractionations are (at 25 C): quartz-organic Ge = 4-5,quartz-Ge(OH)4 =0.9,quartz-GeO(OH)3- =1.5,quartz-albite=0.6,quartz-K-feldspar=0.4 and quartz-olivine=3.9 per mil. The large fractionations between inorganic Ge complexes and organic Ge ones could be used to distinguish the possible bio-involving processes. Our results suggest a good explanation to the experimental observations of Siebert et al. (2006) and Rouxel et al. (2006) and provide important constraints to the study of Ge cycle in ocean.

  11. 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.

  12. Extracting Spectroscopic Factors of Argon Isotopes from Transfer Reactions

    NASA Astrophysics Data System (ADS)

    Manfredi, Juan; Tsang, Betty; Lynch, Bill; Barney, Jon; Estee, Justin; Sweany, Sean; Cerizza, Giordano; Iwasaki, Hironori; Loelius, Charles; Ayyad, Yassid; Anderson, Corinne; Xiao, Zhigang; Li, Zihuang; Lee, Jenny; Xu, Zhengyu; Rogers, Andrew; Brown, Kyle; Pruitt, Cole; Sobotka, Lee; Charity, Robert; Langer, Christoph; Chajecki, Zbigniew; Jones, Kate; Smith, Karl; Winkelbauer, Jack

    2016-09-01

    There is a discrepancy of spectroscopic factors (SFs) of argon isotopes depending on the use of transfer reactions or knockout reactions. Understanding how the SFs of these isotopes change across the isotopic chain is important for understanding how single particle structure changes with neutron number. The transfer reactions 34Ar(p,d) and 46Ar(p,d) were measured at the National Superconducting Cyclotron Laboratory using the High Resolution Array (HiRA) to detect the outgoing deuterons and the S800 Spectrometer to detect the heavy recoil. SFs can be extracted from these angular distributions via DWBA calculations. Preliminary findings on the data will be presented. National Nuclear Security Administration Stewardship Science Graduate Fellowship.

  13. Photon Scattering from the Stable Even-Mass Mo Isotopes Below the Neutron-Separation Energy

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Hutcheson, A.; Kwan, E.; Tonchev, A. P.; Tornow, W.; Angell, C.; Hammond, S.; Karwowski, H. J.; Kelley, J. H.; Schwengner, R.; Dönau, F.; Wagner, A.

    2008-10-01

    We present results from photon-scattering experiments on the stable even-mass molybdenum isotopes below the neutron-separation energy carried out with bremsstrahlung at the superconducting electron accelerator ELBE at the Research Center Dresden-Rossendorf in Germany, and with monoenergetic photon beams at the HIγS facility at TUNL. We applied statistical methods in order to correct for the branching and cascade transitions and to determine the photoabsorption cross section. The obtained results allowed us to extend the tail of the Giant Dipole Resonance below the (,) threshold down to 4 MeV. The photoabsorption cross sections deduced from the present experiments show that the dipole strength increases with the neutron number of the Mo isotopes. The experimental results are discussed in the frame of Quasiparticle-Random-Phase-Approximation in a deformed basis which describe the increasing strength as a result of the deformation.

  14. Extraction, separation, and intramolecular carbon isotope characterization of athabasca oil sands acids in environmental samples.

    PubMed

    Ahad, Jason M E; Pakdel, Hooshang; Savard, Martine M; Simard, Marie-Christine; Smirnoff, Anna

    2012-12-04

    Here we report a novel approach to extract, isolate, and characterize high molecular weight organic acids found in the Athabasca oil sands region using preparative capillary gas chromatography (PCGC) followed by thermal conversion/elemental analysis-isotope ratio mass spectrometry (TC/EA-IRMS). A number of different "naphthenic acids" surrogate standards were analyzed as were samples from the bitumen-rich unprocessed McMurray Formation, oil sands process water, groundwater from monitoring wells, and surface water from the Athabasca River. The intramolecular carbon isotope signature generated by online pyrolysis (δ(13)C(pyr)) showed little variation (±0.6‰) within any given sample across a large range of mass fractions separated by PCGC. Oil sand, tailings ponds, and deep McMurray Formation groundwater were significantly heavier (up to ∼9‰) compared to surface water and shallow groundwater samples, demonstrating the potential use of this technique in source apportionment studies.

  15. 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.

  16. Nitrogen Isotopes in Olivine Separates from Volcanic Arcs, Hot Spots and Continental Mantle Xenoliths

    NASA Astrophysics Data System (ADS)

    Fischer, T. P.; Takahata, N.; Sano, Y.; Hilton, D. R.

    2004-12-01

    We report the first nitrogen isotopic data of olivine separates from volcanic arcs (Cerro Negro, Nicaragua; Izalco, El Salvador; Turrialba, Costa Rica; Ichinomegata, Japan). In addition, we report nitrogen isotopic data of olivine separates from ocean islands (Hawaii, Reunion, Iceland) and continental mantle xenoliths (San Carlos, Arizona). Samples were processed by crushing and analyzed using a modified noble gas mass spectrometer (VG3400). N concentrations range from 0.6 to 22 micro ccSTP/g olivine. The 15N/14N ratios (expressed in the δ 15N notation where δ 15N sample = {[(15N/14N)sample/(15N/14N)Air]-1} X 1000) of olivine separates are distinctly different from air (0.0‰ ) and range from lower than mean MORB (- 5 ‰ ) to values characteristic of (subducted) oceanic sediments (+ 7 ‰ ). Positive δ 15N values are found in olivines from volcanic arcs: Cerro Negro 1992 ash (+ 6.2 ± 1.6‰ ), Izalco lava flow (+ 5.1 ± 0.7‰ ), Ichinomengata spinel lherzolite (+ 1.1 ± 0.5 ‰ ) with the exception of Turrialba lava (- 1.7 ± 2.5‰ ). Olivines from hot spots have both positive and negative δ 15N signatures: Iceland, Theistareykir - northern rift zone (- 8± 1.6 ‰ ), Hawaii, dunite from 1801 Kaupulehu flow of Hualuai volcano (+ 3.1 ± 0.3 ‰ ) and Reunion dunite (+ 0.2 ± 0.5‰ ). The San Carlos mantle xenolith has a value of - 1.5 ± 2.5‰ . 40Ar/36Ar ratios of the samples as determined in this study or reported in the literature are significantly higher than air (295.5) in olivines from Ichinomegata, San Carlos, Iceland, Reunion and Hawaii. The olivines from Cerro Negro have a 40Ar/36Ar ratio of 306, close to that of air. The 3He/4He ratios of the samples are higher than the MORB value of 8.0 RA (RA is the 3He/4He of air), the exception being Cerro Negro (6.1 RA). Hawaii, Reunion and Iceland have 3He/4He of 10.3, 12.9 and 12.3 RA, respectively. δ 15N signatures of fumarole gas samples collected at Cerro Negro (+ 4.9 ±0.1 ‰ ), Turrialba (- 1.0 ±0

  17. RAPID SEPARATION METHOD FOR 237NP AND PU ISOTOPES IN LARGE SOIL SAMPLES

    SciTech Connect

    Maxwell, S.; Culligan, B.; Noyes, G.

    2010-07-26

    A new rapid method for the determination of {sup 237}Np and Pu isotopes in soil and sediment samples has been developed at the Savannah River Site Environmental Lab (Aiken, SC, USA) that can be used for large soil samples. The new soil method utilizes an acid leaching method, iron/titanium hydroxide precipitation, a lanthanum fluoride soil matrix removal step, and a rapid column separation process with TEVA Resin. The large soil matrix is removed easily and rapidly using this two simple precipitations with high chemical recoveries and effective removal of interferences. Vacuum box technology and rapid flow rates are used to reduce analytical time.

  18. 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.

  19. Laser enhanced microwave plasma isotope separation. Final report, September 30, 1992--September 29, 1995

    SciTech Connect

    Brake, M.L.; Gilgenbach, R.M.

    1996-06-01

    The experimental research was to focus on laser excitation of a low abundance isotope and then ionize and separate the isotope of low abundance using a microwave/ECR discharge at 2.45 GHz. A small compact electron cyclotron resonance ion source, which uses permanent magnets, was constructed during this project. The dye laser was purchased and later an excimer laser had to also be purchased because it turned out that the dye laser could not be pumped by our copper laser. It was intended that the dye laser be tuned to a wavelength of 670.8 nm, which would excite {sup 6}Li which would then be preferentially ionized by the ECR source and collected with a charged grid. The degree of enrichment was to be determined using thermal ionization mass spectrometry. The final objective of this project was to assess the feasibility of this system to large-scale production of stable isotopes. However the funding of this project was interrupted and we were not able to achieve all of our goals.

  20. Analogy between mission critical detection in distributed systems and 13C isotope separation column

    NASA Astrophysics Data System (ADS)

    Boca, Maria L.; Secara, Mihai

    2015-02-01

    Carbon represents the fourth most abundant chemical element in the world, having two stable and one radioactive isotope. The 13 Carbon 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 [2]. Distributed systems are increasingly being applied in critical real-time applications and their complexity forces programmers to use design methods which guarantee correctness and increase the maintainability of the products. Objectoriented methodologies are widely used to cope with complexity in any kind of system, but most of them lack a formal foundation to allow the analysis and verification of designs, which is one of the main requirements for dealing with concurrent and reactive systems. This research is intended to make an analogy between two tips of industrial processes, one 13C Isotope Separation Column and other one distributed systems. We try to highlight detection of "mission critical "situations for this two processes and show with one is more critical and needs deeply supervisyon [1], [3].

  1. Rapid U separation and its precise isotopic measurements using ICP-QMS

    NASA Astrophysics Data System (ADS)

    Douville, E.; Salle, E.; Gourgiotis, A.; Ayrault, S.; Frank, N.

    2007-12-01

    Here we present a largely simplified analytical separation technique for U from marin carbonates and sediments and U isotopic measurements obtained by inductively coupled plasma-source quadrupole mass spectrometer (ICP-QMS) Xseries II - Thermo Scientific. The separation of U is done from dissolved carbonates and sediments using a single ion exchange column packed with ~500 μg of UTEVA resin from EICHROM industries. The column is pre-cleaned and loaded by several rinses of MilliQ water and 3N HNO3. Then earth alkali, transition metals and lanthanides are eluted quantitatively using 3N HNO3. Pure Th and U solutions are then successively extracted from the column using 3N HCl and 1N HCl at ~100% yield. U solutions at ~25-50 ppb were injected into the ICP-QMS at conventional sample flow rates of approximately 1ml/minute, without particular injection systems such as a desolvator or μ - nebuliser. 30 scans with 180 sweeps and a dwell time of 50 ms per isotope were used to collect 233U, 234U, 235U and 236U on an electron multiplier. Baseline sensitivity was followed on mass 228 with <1cps at ~ 1000cps on mass 234. Then, mass discrimination was corrected using the 233U/236U spike of known isotopic ratio and HU1 reference solutions were used to test the reproducibility and to correct drifts using standard - sample bracketing. Overall ICPMS analyses yield a stunning reproducibility of <0.4 % at 2 σ, which is close to the one obtained by conventional TIMS instruments ~0.2-0.4 %. We have applied this technique to organic rich sediments and marine carbonate samples previously measured by TIMS and found a perfect agreement for both U concentration and its isotopic composition. This rapid and effective chemical purification and isotopic measurement of U allows to process more than 20 samples a day allowing to investigate large numbers of natural samples for weathering, tracer and geochronological studies.

  2. 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.

  3. Recent advances in SRS on hydrogen isotope separation using thermal cycling absorption process

    SciTech Connect

    Xiao, X.; Kit Heung, L.; Sessions, H.T.

    2015-03-15

    TCAP (Thermal Cycling Absorption Process) is a gas chromatograph in principle using palladium in the column packing, but it is unique in the fact that the carrier gas, hydrogen, is being isotopically separated and the system is operated in a semi-continuous manner. TCAP units are used to purify tritium. The recent 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 1/10 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.

  4. Recent great impact by an Isotope Separator On-Line (ISOL) in nuclear and radiochemistry.

    PubMed

    Sakama, Minoru

    2016-01-01

    On April 9 2015, the Letter article titled "Measurement of the first ionization potential of lawrencium, element 103" is now published at News and Views on Nature (2015) which has been performed by our remarkably Japanese colleagues of nuclear and radiochemistry at JAEA (Japan Atomic Energy Agency). In this review, the author will state that the isotope separator on-line (ISOL) our regularly used, one of mass separation techniques, with a thermal surface ionization makes possible for determining the ionization potential of lawrencium based on the fruitful fundations of developing the ISOL system until now and also ever studying searches for unknown nuclei and these nuclear decay properties around actinide region in the past 20 years.

  5. Stable hydrogen isotopic analysis of nanomolar molecular hydrogen by automatic multi-step gas chromatographic separation.

    PubMed

    Komatsu, Daisuke D; Tsunogai, Urumu; Kamimura, Kanae; Konno, Uta; Ishimura, Toyoho; Nakagawa, Fumiko

    2011-11-15

    We have developed a new automated analytical system that employs a continuous flow isotope ratio mass spectrometer to determine the stable hydrogen isotopic composition (δD) of nanomolar quantities of molecular hydrogen (H(2)) in an air sample. This method improves previous methods to attain simpler and lower-cost analyses, especially by avoiding the use of expensive or special devices, such as a Toepler pump, a cryogenic refrigerator, and a special evacuation system to keep the temperature of a coolant under reduced pressure. Instead, the system allows H(2) purification from the air matrix via automatic multi-step gas chromatographic separation using the coolants of both liquid nitrogen (77 K) and liquid nitrogen + ethanol (158 K) under 1 atm pressure. The analytical precision of the δD determination using the developed method was better than 4‰ for >5 nmol injections (250 mL STP for 500 ppbv air sample) and better than 15‰ for 1 nmol injections, regardless of the δD value, within 1 h for one sample analysis. Using the developed system, the δD values of H(2) can be quantified for atmospheric samples as well as samples of representative sources and sinks including those containing small quantities of H(2) , such as H(2) in soil pores or aqueous environments, for which there is currently little δD data available. As an example of such trace H(2) analyses, we report here the isotope fractionations during H(2) uptake by soils in a static chamber. The δD values of H(2) in these H(2)-depleted environments can be useful in constraining the budgets of atmospheric H(2) by applying an isotope mass balance model.

  6. 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.

  7. Comparison of methods for separating small quantities of hydrogen isotopes from an inert gas

    SciTech Connect

    Willms, R.S.; Tuggle, D.; Birdsell, S.; Parkinson, J.; Price, B.; Lohmeir, D.

    1998-03-01

    It is frequent within tritium processing systems that a small amount of hydrogen isotopes (Q{sub 2}) must be separated from an inert gas such as He, Ar and N{sub 2}. Thus, a study of presently available technologies for effecting such a separation was performed. A base case and seven technology alternatives were identified and a simple design of each was prepared. These technologies included oxidation-adsorption-metal bed reduction, oxidation-adsorption-palladium membrane reactor, cryogenic adsorption, cryogenic trapping, cryogenic distillation, hollow fiber membranes, gettering and permeators. It was found that all but the last two methods were unattractive for recovering Q{sub 2} from N{sub 2}. Reasons for technology rejection included (1) the method unnecessarily turns the hydrogen isotopes into water, resulting in a cumbersome and more hazardous operation, (2) the method would not work without further processing, and (3) while the method would work, it would only do so in an impractical way. On the other hand, getters and permeators were found to be attractive methods for this application. Both of these methods would perform the separation in a straightforward, essentially zero-waste, single step operation. The only drawback for permeators was that limited low-partial Q{sub 2} pressure data is available. The drawbacks for getters are their susceptibility to irreversible and exothermic reaction with common species such as oxygen and water, and the lack of long-term operation of such beds. More research is envisioned for both of these methods to mature these attractive technologies.

  8. Theoretical evaluation of isotopic fractionation factors in oxidation reactions of benzene, phenol and chlorophenols.

    PubMed

    Adamczyk, Paweł; Paneth, Piotr

    2011-09-01

    We have studied theoretically the rate determining steps of reactions of benzene with permanganate, perchlorate, ozone and dioxygen in the gas phase and aqueous solution as well as phenol and dichlorophenol in protonated and unprotonated forms in aqueous solution. Kinetic isotope effects were then calculated for all carbon atoms and based on their values isotopic fractionation factors corresponding to compound specific isotopic analysis have been evaluated. The influence of the oxidant, substituents, environment and protonation on the isotopic fractionation factors has been analyzed.

  9. 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.

  10. Breakthrough curve analysis of pressure swing adsorption for hydrogen isotope separation

    SciTech Connect

    Kotoh, K.; Tanaka, M.; Sakamoto, T.; Nakamura, Y.; Asakura, Y.; Uda, T.; Sugiyama, T.

    2008-07-15

    For the purpose of developing an effective system for hydrogen isotope separation, we have been studying the adsorption-desorption dynamic behavior of hydrogen and deuterium in a packed-bed column with synthetic zeolites, aimed at applying the pressure swing adsorption process. The adsorption behavior of molecules in the packed-bed is reflected in the breakthrough curves. To understand the characteristic behaviors of hydrogen isotopes in the packed-bed, we carried out breakthrough experiments in a conventional adsorption process and in a practical process following sequential processes alternating between adsorption and desorption. From the former experiments, the results were obtained that the overall mass transfer was influenced by longitudinal dispersion relating to the superficial velocity and that the process governing the mass transfer within adsorbents was diffusion in the macro-pores of pellets. In the latter experiments, unique profile breakthrough curves were observed. These curves can be described with the numerical simulation assuming the initial distributions in a packed-bed. (authors)

  11. Golan Heights Groundwater Systems: Separation By REE+Y And Stable Isotopes

    NASA Astrophysics Data System (ADS)

    Siebert, C.; Geyer, S.; Knoeller, K.; Roediger, T.; Weise, S.; Dulski, P.; Moeller, P.; Guttman, J.

    2008-12-01

    In a semi-arid to arid country like Israel, all freshwater resources are under (over-) utilization. Particularly, the Golan Heights rank as one of the most important extraction areas of groundwater of good quality and quantity. Additionally the mountain range feed to a high degree the most important freshwater reservoir of Israel, the Sea of Galilee. Hence, knowing the sources and characters of the Golan Heights groundwater systems is an instantaneous demand regarding sustainable management and protection. Within the "German-Israeli-Jordanian-Palestinian Joint Research Program for the Sustainable Utilisation of Aquifer Systems", hundreds of water samples were taken from all over the Jordan-Dead Sea rift-system to understand groundwater flow-systems and salinisation. For that purpose, each sample was analysed for major and minor ions, rare earth elements including yttrium (REY) and stable isotopes of water (d18O, d2H). The REY distribution in groundwater is established during infiltration by the first water-rock interaction and consequently reflects the leachable components of sediments and rocks of the recharge area. In well- developed flow-systems, REY are adsorbed onto pore surfaces are in equilibrium with the percolating groundwater, even if the lithology changes (e.g. inter-aquifer flow). Thus, groundwater sampled from wells and springs still show the REY distribution pattern established in the recharge area. Since high temperatures do not occur in Golan Heights, d2H and d18O are less controlled by water-rock interaction than by climatic and geomorphological factors at the time of replenishment. Applying the REY signature as a grouping criterion of groundwaters, d18O vs. d2H plots yield a new dimension in interpreting isotope data. The combined use of hydrochemical and isotopic methods enabled us to contain the areas of replenishment and the flow-paths of all investigated groundwater in the Golan Heights. Despite location, salinity or temperature of spring or

  12. Identification of new astatine isotopes using the gas-filled magnetic separator, Sassy

    SciTech Connect

    Yashita, S.

    1983-01-01

    A He-filled on-line separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two-neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +/- 0.02 MeV and 180 +/- 80 msec for /sup 194/At, and 7.12 +/- 0.02 MeV and 200 +/- 100 msec for /sup 195/At.

  13. Identification of new astatine isotopes using the gas-filled magnetic separator, SASSY

    SciTech Connect

    Yashita, S.

    1984-02-01

    A He-filled on-line mass separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two- neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +- 0.02 MeV and 180 +- 80 msec for /sup 194/At, and 7.12 +- 0.02 MeV and 200 +- 100 msec for /sup 195/At. 66 references.

  14. New Half-lives of r-process Zn and Ga Isotopes Measured with Electromagnetic Separation

    SciTech Connect

    Madurga, M; Surman, Rebecca; Borzov, Ivan N; Grzywacz, R.; Rykaczewski, Krzysztof Piotr; Gross, Carl J; Miller, D; Stracener, Daniel W; Batchelder, Jon Charles; Brewer, N.T.; Cartegni, L.; Hamilton, J. H.; Hwang, J. K.; Liu, S. H.; Ilyushkin, S.; Karny, M.; Korgul, A.; Krolas, W.; Kuzniak, A.; Mazzocchi, C.; Mendez, II, Anthony J; Miernik, K.; Padgett, Stephen; Paulauskas, S.; Ramayya, A. V.; Winger, J. A.; Wolinska-Cichocka, Marzena; Zganjar, E. F.

    2012-01-01

    The {beta} decays of neutron-rich nuclei near the doubly magic {sup 78}Ni were studied at the Holifield Radioactive Ion Beam Facility using an electromagnetic isobar separator. The half-lives of {sup 82}Zn (228 {+-} 10 ms), {sup 83}Zn (117 {+-} 20 ms), and {sup 85}Ga (93 {+-} 7 ms) were determined for the first time. These half-lives were found to be very different from the predictions of the global model used in astrophysical simulations. A new calculation was developed using the density functional model, which properly reproduced the new experimental values. The robustness of the new model in the {sup 78}Ni region allowed us to extrapolate data for more neutron-rich isotopes. The revised analysis of the rapid neutron capture process in low entropy environments with our new set of measured and calculated half-lives shows a significant redistribution of predicted isobaric abundances strengthening the yield of A > 140 nuclei.

  15. RADIATION STABILITY OF NAFION MEMBRANES USED FOR ISOTOPE SEPARATION BY PROTON EXCHANGE MEMBRANE ELECTROLYSIS

    SciTech Connect

    Fox, E

    2009-05-15

    Proton Exchange Membrane Electrolyzers have potential interest for use for hydrogen isotope separation from water. In order for PEME to be fully utilized, more information is needed on the stability of Nafion when exposed to radiation. This work examines Nafion 117 under varying exposure conditions, including dose rate, total dosage and atmospheric condition. Analytical tools, such as FT-IR, ion exchange capacity, DMA and TIC-TOC were used to characterize the exposed membranes. Analysis of the water from saturated membranes can provide important data on the stability of the membranes during radiation exposure. It was found that the dose rate of exposure plays an important role in membrane degradation. Potential mechanisms for membrane degradation include peroxide formation by free radicals.

  16. Factors affecting the isotopic composition of organic matter. (1) Carbon isotopic composition of terrestrial plant materials.

    PubMed

    Yeh, H W; Wang, W M

    2001-07-01

    The stable isotope composition of the light elements (i.e., H, C, N, O and S) of organic samples varies significantly and, for C, is also unique and distinct from that of inorganic carbon. This is the result of (1) the isotope composition of reactants, (2) the nature of the reactions leading to formation and post-formational modification of the samples, (3) the environmental conditions under which the reactions took place, and (4) the relative concentration of the reactants compared to that of the products (i.e., [products]/[reactants] ratio). This article will examine the carbon isotope composition of terrestrial plant materials and its relationship with the above factors. delta13C(PDB) values of terrestrial plants range approximately from -8 to -38%, inclusive of C3-plants (-22 to -38%), C4-plants (-8 to -15%) and CAM-plants (-13 to -30%). Thus, the delta13C(PDB) values largely reflect the photosynthesis pathways of a plant as well as the genetics (i.e., species difference), delta13C(PDB) values of source CO2, relevant humidity, CO2/O2 ratios, wind and light intensity etc. Significant variations in these values also exist among different tissues, different portions of a tissue and different compounds. This is mainly a consequence of metabolic reactions. Animals mainly inherit the delta13C(PDB) values of the foods they consume; therefore, their delta13C(PDB) values are similar. The delta13C(PDB) values of plant materials, thus, contain information regarding the inner workings of the plants, the environmental conditions under which they grow, the delta13C(PDB) values of CO2 sources etc., and are unique. Furthermore, this uniqueness is passed on to their derivative matter, such as animals, humus etc. Hence, they are very powerful tools in many areas of research, including the ecological and environmental sciences.

  17. Carbon isotope separation and molecular formation in laser-induced plasmas by laser ablation molecular isotopic spectrometry.

    PubMed

    Dong, Meirong; Mao, Xianglei; Gonzalez, Jhanis J; Lu, Jidong; Russo, Richard E

    2013-03-05

    Laser ablation molecular isotopic spectrometry (LAMIS) recently was reported for rapid isotopic analysis by measuring molecular emission from laser-induced plasmas at atmospheric pressure. This research utilized the LAMIS approach to study C2 molecular formation from laser ablation of carbon isotopic samples in a neon gas environment at 0.1 MPa. The isotopic shift for the Swan system of the C2 Δν = 1 band was chosen for carbon isotope analysis. Temporal and spatial resolved measurements of (12)C2, (12)C(13)C, and (13)C2 show that C2 forms from recombination reactions in the plasma. A theoretical simulation was used to determine the temperature from the molecular bands and to extract the isotopic ratio of (12)C/(13)C derived from (12)C2, (12)C(13)C, and (13)C2. Our data show that the ratio of (12)C/(13)C varies with time after the laser pulse and with distance above the sample. (12)C/(13)C deviates from the nominal ratio (2:1) at early times and closest to the sample surface. These measurements provide understanding of the chemical processes in the laser plasma and analytical improvement using LAMIS.

  18. Isotopic separation of snowmelt runoff during an artificial rain-on-snow event

    NASA Astrophysics Data System (ADS)

    Juras, Roman; Pavlasek, Jirka; Šanda, Martin; Jankovec, Jakub; Linda, Miloslav

    2013-04-01

    Rain-on-snow events are common phenomenon in the climate conditions of central Europe, mainly during the spring snowmelt period. These events can cause serious floods in areas with seasonal snow. The snowpack hit by rain is able to store a fraction of rain water, but runoff caused by additional snowmelt also increases. Assessment of the rainwater ratio contributing to the outflow from the snowpack is therefore critical for discharge modelling. A rainfall simulator and water enriched by deuterium were used for the study of rainwater behaviour during an artificial rain-on-snow event. An area of 1 m2 of the snow sample, which was 1.2 m deep, consisting of ripped coarse-grained snow, was sprayed during the experiment with deuterium enriched water. The outflow from the snowpack was measured and samples of outflow water were collected. The isotopic content of deuterium was further analyzed from these samples by means of laser spectroscopy for the purpose of hydrograph separation. The concentration of deuterium in snow before and after the experiment was also investigated. The deuterium enriched water above the natural concentration of deuterium in snowpack was detected in the outflow in 7th minute from start of spraying, but the significant increase of deuterium concentration in outflow was observed in 19th minute. The isotopic hydrograph separation estimated, that deuterium enriched rainwater became the major part (> 50% volumetric) of the outflow in 28th minute. The culmination of the outflow (1.23 l min-1) as well as deuterium enriched rainwater fraction (63.5%) in it occurred in 63th minute, i.e. right after the end of spraying. In total, 72.7 l of deuterium enriched water was sprayed on the snowpack in 62 minutes. Total volume of outflow (after 12.3 hours) water was 97.4 l, which contained 48.3 l of deuterium enriched water (i.e. 49.6 %) and 49.1 l (50.4 %) of the melted snowpack. The volume of 24.4 l of deuterium enriched spray-water was stored in the snowpack. The

  19. Spatial variability in the isotopic composition of rainfall in a small headwater catchment and its effect on hydrograph separation

    NASA Astrophysics Data System (ADS)

    Fischer, Benjamin M. C.; van Meerveld, H. J. (Ilja); Seibert, Jan

    2017-04-01

    Isotope hydrograph separation (IHS) is a valuable tool to study runoff generation processes. To perform an IHS, samples of baseflow (pre-event water) and streamflow are taken at the catchment outlet. For rainfall (event water) either a bulk sample is collected or it is sampled sequentially during the event. For small headwater catchment studies, event water samples are usually taken at only one sampling location in or near the catchment because the spatial variability in the isotopic composition of rainfall is assumed to be small. However, few studies have tested this assumption. In this study, we investigated the spatiotemporal variability in the isotopic composition of rainfall and its effects on IHS results using detailed measurements from a small pre-alpine headwater catchment in Switzerland. Rainfall was sampled sequentially at eight locations across the 4.3 km2 Zwäckentobel catchment and stream water was collected in three subcatchments (0.15, 0.23, and 0.70 km2) during ten events. The spatial variability in rainfall amount, average and maximum rainfall intensity and the isotopic composition of rainfall was different for each event. There was no significant relation between the isotopic composition of rainfall and total rainfall amount, rainfall intensity or elevation. For eight of the ten studied events the temporal variability in the isotopic composition of rainfall was larger than the spatial variability in the rainfall isotopic composition. The isotope hydrograph separation results, using only one rain sampler, varied considerably depending on which rain sampler was used to represent the isotopic composition of event water. The calculated minimum pre-event water contributions differed up to 60%. The differences were particularly large for events with a large spatial variability in the isotopic composition of rainfall and a small difference between the event and pre-event water isotopic composition. Our results demonstrate that even in small catchments

  20. 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.

  1. 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 %.

  2. Factors influencing adoption of manure separation technology in The Netherlands.

    PubMed

    Gebrezgabher, Solomie A; Meuwissen, Miranda P M; Kruseman, Gideon; Lakner, Dora; Oude Lansink, Alfons G J M

    2015-03-01

    Manure separation technologies are essential for sustainable livestock operations in areas with high livestock density as these technologies result in better utilization of manure and reduced environmental impact. Technologies for manure separation have been well researched and are ready for use. Their use, however, has been limited to the Netherlands. This paper investigates the role of farm and farmer characteristics and farmers' attitudes toward technology-specific attributes in influencing the likelihood of the adoption of mechanical manure separation technology. The analysis used survey data collected from 111 Dutch dairy farmers in 2009. The results showed that the age and education level of the farmer and farm size are important variables explaining the likelihood of adoption. In addition to farm and farmer characteristics, farmers' attitudes toward the different attributes of manure separation technology significantly affect the likelihood of adoption. The study generates useful information for policy makers, technology developers and distributors in identifying the factors that impact decision-making behaviors of farmers.

  3. First Principles Calculation on Equilibrium Si Isotope Fractionation Factors and its Implementation on Si Isotope Distributions in Earth Surface Environments

    NASA Astrophysics Data System (ADS)

    Liu, Y.; He, H. T.; Zhu, C.

    2014-12-01

    Several important equilibrium Si isotope fractionation factors are calculated here. We use a so-called volume-variable-cluster-model (VVCM) method for solids and the "water-droplet" method for aqueous species for isotope fractionation calculation at the same quantum chemistry level. The calculation results show that several silicate minerals, such as quartz, feldspar, kaolinite, etc., all enrich heavy Si isotopes relative to aqueous H4SiO4 and can be up to 3.3‰ at 25°C, different from most field observations. Meanwhile stable organosilicon complexes can enrich even lighter Si isotopes than aqueous H4SiO4. For explaining the difference between the calculation results and field observations, we calculate the kinetic isotope effect (KIE) associated with the formation of amorphous silica, and find that amorphous silica will enrich extremely light Si isotopes. From amorphous silica to crystalline quartz, the structural adjustment & transition needs getting rid of small amount of Si to re-organize the structure. Light Si isotopes will be preferentially lost and let the final crystalline quartz with a little bit more heavy Si isotopes. However, such late-stage Si heavy isotope enrichment cannot erase the total isotopic signal, crystalline quartz still inherit much light Si isotopic composition from amorphous quartz. That is the reason for the discrepancy between the calculation results and the field observations, because the formation of amorphous quartz is under a non-equilibrium process but theoretical calculations are for equilibrium isotope fractionations. With accurate equilibrium fractionation factors provided here, Si isotope distributions in earth surface environments including soil, groundwater and plants can be further interpreted. We find that δ30Si variations in soil are mainly driven by secondary minerals precipitation and adsorption. Also, bulk soil δ30Si maybe have a parabolic distribution with soil age, with a minimum value at where allophane is

  4. The importance of snowmelt spatiotemporal variability for isotope-based hydrograph separation in a high-elevation catchment

    NASA Astrophysics Data System (ADS)

    Schmieder, Jan; Hanzer, Florian; Marke, Thomas; Garvelmann, Jakob; Warscher, Michael; Kunstmann, Harald; Strasser, Ulrich

    2016-12-01

    Seasonal snow cover is an important temporary water storage in high-elevation regions. Especially in remote areas, the available data are often insufficient to accurately quantify snowmelt contributions to streamflow. The limited knowledge about the spatiotemporal variability of the snowmelt isotopic composition, as well as pronounced spatial variation in snowmelt rates, leads to high uncertainties in applying the isotope-based hydrograph separation method. The stable isotopic signatures of snowmelt water samples collected during two spring 2014 snowmelt events at a north- and a south-facing slope were volume weighted with snowmelt rates derived from a distributed physics-based snow model in order to transfer the measured plot-scale isotopic composition of snowmelt to the catchment scale. The observed δ18O values and modeled snowmelt rates showed distinct inter- and intra-event variations, as well as marked differences between north- and south-facing slopes. Accounting for these differences, two-component isotopic hydrograph separation revealed snowmelt contributions to streamflow of 35 ± 3 and 75 ± 14 % for the early and peak melt season, respectively. These values differed from those determined by formerly used weighting methods (e.g., using observed plot-scale melt rates) or considering either the north- or south-facing slope by up to 5 and 15 %, respectively.

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

    SciTech Connect

    Liezers, Martin; Olsen, Khris B.; Mitroshkov, Alexandre V.; Duckworth, Douglas C.

    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, 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.

  6. Optimization and comparison of simultaneous and separate acquisition protocols for dual isotope myocardial perfusion SPECT

    NASA Astrophysics Data System (ADS)

    Ghaly, Michael; Links, Jonathan M.; Frey, Eric C.

    2015-07-01

    Dual-isotope simultaneous-acquisition (DISA) rest-stress myocardial perfusion SPECT (MPS) protocols offer a number of advantages over separate acquisition. However, crosstalk contamination due to scatter in the patient and interactions in the collimator degrade image quality. Compensation can reduce the effects of crosstalk, but does not entirely eliminate image degradations. Optimizing acquisition parameters could further reduce the impact of crosstalk. In this paper we investigate the optimization of the rest Tl-201 energy window width and relative injected activities using the ideal observer (IO), a realistic digital phantom population and Monte Carlo (MC) simulated Tc-99m and Tl-201 projections as a means to improve image quality. We compared performance on a perfusion defect detection task for Tl-201 acquisition energy window widths varying from 4 to 40 keV centered at 72 keV for a camera with a 9% energy resolution. We also investigated 7 different relative injected activities, defined as the ratio of Tc-99m and Tl-201 activities, while keeping the total effective dose constant at 13.5 mSv. For each energy window and relative injected activity, we computed the IO test statistics using a Markov chain Monte Carlo (MCMC) method for an ensemble of 1,620 triplets of fixed and reversible defect-present, and defect-absent noisy images modeling realistic background variations. The volume under the 3-class receiver operating characteristic (ROC) surface (VUS) was estimated and served as the figure of merit. For simultaneous acquisition, the IO suggested that relative Tc-to-Tl injected activity ratios of 2.6-5 and acquisition energy window widths of 16-22% were optimal. For separate acquisition, we observed a broad range of optimal relative injected activities from 2.6 to 12.1 and acquisition energy window of widths 16-22%. A negative correlation between Tl-201 injected activity and the width of the Tl-201 energy window was observed in these ranges. The results

  7. Optimization and comparison of simultaneous and separate acquisition protocols for dual isotope myocardial perfusion SPECT

    PubMed Central

    Ghaly, Michael; Links, Jonathan M; Frey, Eric C

    2015-01-01

    Dual-isotope simultaneous-acquisition (DISA) rest-stress myocardial perfusion SPECT (MPS) protocols offer a number of advantages over separate acquisition. However, crosstalk contamination due to scatter in the patient and interactions in the collimator degrade image quality. Compensation can reduce the effects of crosstalk, but does not entirely eliminate image degradations. Optimizing acquisition parameters could further reduce the impact of crosstalk. In this paper we investigate the optimization of the rest Tl-201 energy window width and relative injected activities using the ideal observer (IO), a realistic digital phantom population and Monte Carlo (MC) simulated Tc-99m and Tl-201 projections as a means to improve image quality. We compared performance on a perfusion defect detection task for Tl-201 acquisition energy window widths varying from 4 to 40 keV centered at 72 keV for a camera with a 9% energy resolution. We also investigated 7 different relative injected activities, defined as the ratio of Tc-99m and Tl-201 activities, while keeping the total effective dose constant at 13.5 mSv. For each energy window and relative injected activity, we computed the IO test statistics using a Markov chain Monte Carlo (MCMC) method for an ensemble of 1,620 triplets of fixed and reversible defect-present, and defect-absent noisy images modeling realistic background variations. The volume under the 3-class receiver operating characteristic (ROC) surface (VUS) was estimated and served as the figure of merit. For simultaneous acquisition, the IO suggested that relative Tc-to-Tl injected activity ratios of 2.6–5 and acquisition energy window widths of 16–22% were optimal. For separate acquisition, we observed a broad range of optimal relative injected activities from 2.6 to 12.1 and acquisition energy window of widths 16–22%. A negative correlation between Tl-201 injected activity and the width of the Tl-201 energy window was observed in these ranges. The results

  8. 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.

  9. Isotope Separation and Advanced Manufacturing Technology. ISAM semiannual report, Volume 3, Number 1, October 1993--March 1994

    SciTech Connect

    Carpenter, J.; Kan, T.

    1994-10-01

    This is the fourth issue of a semiannual report for the Isotope Separation and Advanced Materials Manufacturing (ISAM) Technology Program at Lawrence Livermore National Laboratory. Primary objectives include: (I) the Uranium Atomic Vapor Laser Isotope Separation (UAVLIS) process, which is being developed and prepared for deployment as an advanced uranium enrichment capability; (II) Advanced manufacturing technologies, which include industrial laser and E-beam material processing and new manufacturing technologies for uranium, plutonium, and other strategically important materials in support of DOE and other national applications. This report features progress in the ISAM Program from October 1993 through March 1994. Selected papers were indexed separately for inclusion in the Energy Science and Technology Database.

  10. Hydrograph separation using stable isotopes, silica and electrical conductivity: an alpine example

    NASA Astrophysics Data System (ADS)

    Laudon, Hjalmar; Slaymaker, Olav

    1997-12-01

    Hydrograph separation of runoff events in two nested alpine/subalpine basins in the Coast Mountains of British Columbia was carried out using electrical conductivity, specific concentration of silica and the stable isotopes oxygen-18 and deuterium as hydrological tracers. The methods predicted consistent high pre-storm water contribution for the subalpine site (60-90%) but more variable contribution at the alpine basin outlet (25-90%). The pre-storm water contribution is much larger than had previously been expected. Precipitation is believed to run off as overland flow due to the steep slopes in combination with the hydrophobic soils until it can enter the subsurface environment. The rapid influx of stored water is possibly caused by pressure propagation in the macropore system which could be enhanced by the heavily fractured bedrock and permeable landslide debris acting as efficient hydrological conduits. The study suggests that alternative hydrological tracers such as electrical conductivity and silica concentration can be used under certain hydrological and lithological conditions. These alternative tracers should, however, be verified against more conventional tracers before use, as the behaviour depends on specific characteristics of each basin. At the upper basin outlet, both electrical conductivity (EC) and silica underestimated the pre-storm contribution. At the lower station, silica and EC showed a similar pattern to deuterium and oxygen-18 tracers. The calculated pre-storm component using EC was, however, 10-20% lower than the calculated values from the other three tracers. The advantage of using these alternative tracers is that hydrograph separation results can, a priori, be anticipated.

  11. Preparative separation of arsenate from phosphate by IRA-400 (OH) for oxygen isotopic work.

    PubMed

    Tang, Xiaohui; Berner, Zsolt; Khelashvilli, Pirimze; Norra, Stefan

    2013-02-15

    The paper reports about a series of tests carried out to find out the optimal conditions for the preparative separation of arsenate and phosphate from natural waters, using the anion exchange resin Amberlite IRA-400 (OH). Freundlich isotherms have been constructed on basis of data obtained by stirring different amounts of resin (0.05-1.00 g) with solutions containing 1mg/L As and 10mg/L P in form of arsenate and phosphate and the effect of pH and P/As ratio on adsorption was investigated. It was found that at these concentrations 0.5 g of IRA-400 (OH) can adsorb quantitatively arsenate and phosphate within 1h. In a range of 3.6-11.1, pH seems to have no influence on the adsorption behavior of the resin, but at pH 1.5 the adsorption of both arsenate and phosphate drops to values close to zero. Experiments with solutions with P/As ratios in a range between 1 and 30 have shown that the concentration ratios have also little effect on adsorption. An efficient selective desorption of the anions could be achieved with 2 mol/L HNO3 or HCl, but the use of HCl is impracticable if the separation aims at precipitating arsenate for oxygen isotopic work. The reported adsorption/ desorption properties of the resin are supported also by data obtained by investigating the resin particles with a scanning electron microscope equipped with a fluorescence detection device.

  12. Calculations on Isotope Separation by Laser Induced Photodissociation of Polyatomic Molecules. Final Report

    DOE R&D Accomplishments Database

    Lamb, W. E. Jr.

    1978-11-01

    This report describes research on the theory of isotope separation produced by the illumination of polyatomic molecules by intense infrared laser radiation. Newton`s equations of motion were integrated for the atoms of the SF{sub 6} molecule including the laser field interaction. The first year`s work has been largely dedicated to obtaining a suitable interatomic potential valid for arbitrary configurations of the seven particles. This potential gives the correct symmetry of the molecule, the equilibrium configuration, the frequencies of the six distinct normal modes of oscillation and the correct (or assumed) value of the total potential energy of the molecule. Other conditions can easily be imposed in order to obtain a more refined potential energy function, for example, by making allowance for anharmonicity data. A suitable expression was also obtained for the interaction energy between a laser field and the polyatomic molecule. The electromagnetic field is treated classically, and it would be easily possible to treat the cases of time dependent pulses, frequency modulation and noise.

  13. The direct determination of the masses of unstable atoms with the chalk river on-line isotope separator

    NASA Astrophysics Data System (ADS)

    Sharma, K. S.; Schmeing, H.; Evans, H. C.; Hagberg, E.; Hardy, J. C.; Koslowsky, V. T.

    1989-02-01

    A new technique has been developed to measure the spacing of atomic mass doublets of radioactive isotopes directly with an on-line isotope separator. It relies not on ion detection but on observation of the specific radioactive signature of the isotopes under study. Consequently, line shapes and centroids can be determined, free of interference and with great accuracy, even if the corresponding beams strongly overlap or if they are contaminated by unwanted isobars or isomers. In particular, it is of no consequence if one or both members of the doublet are masked by stable background peaks. Doublets are peak matched as in a conventional mass spectrometer. The technique has been evaluated with beams of radioactive nuclides whose masses are known independently. Based on careful calibrations, two new mass values have been obtained: 72Br, 71 936 340 ± 430 μu and 63Ga, 62 939 570 ± 150 μu.

  14. On-line experimental results of an argon gas cell-based laser ion source (KEK Isotope Separation System)

    NASA Astrophysics Data System (ADS)

    Hirayama, Y.; Watanabe, Y. X.; Imai, N.; Ishiyama, H.; Jeong, S. C.; Jung, H. S.; Miyatake, H.; Oyaizu, M.; Kimura, S.; Mukai, M.; Kim, Y. H.; Sonoda, T.; Wada, M.; Huyse, M.; Kudryavtsev, Yu.; Van Duppen, P.

    2016-06-01

    KEK Isotope Separation System (KISS) has been developed at RIKEN to produce neutron rich isotopes with N = 126 to study the β -decay properties for application to astrophysics. The KISS is an element-selective mass-separation system which consists of an argon gas cell-based on laser ion source for atomic number selection and an ISOL mass-separation system. The argon gas cell of KISS is a key component to stop and collect the unstable nuclei produced in a multi-nucleon transfer reaction, where the isotopes of interest will be selectively ionized using laser resonance ionization. We have performed off- and on-line experiments to study the basic properties of the gas cell as well as of the KISS. We successfully extracted the laser-ionized stable 56Fe (direct implantation of a 56Fe beam into the gas cell) atoms and 198Pt (emitted from the 198Pt target by elastic scattering with a 136Xe beam) atoms from the KISS during the commissioning on-line experiments. We furthermore extracted laser-ionized unstable 199Pt atoms and confirmed that the measured half-life was in good agreement with the reported value.

  15. Practical-scale tests of cryogenic molecular sieve for separating low-concentration hydrogen isotopes from helium

    NASA Astrophysics Data System (ADS)

    Willms, R. S.; Taylor, D. J.; Enoeda, Mikio; Okuno, Kenji

    1994-04-01

    Earlier bench-scale work at the Tritium Systems Test Assembly (TSTA) at Los Alamos National Laboratory examined a number of adsorbents for their suitability for separating low-concentration hydrogen (no tritium) from helium. One of the effective adsorbents was Linde 5A molecular sieve. Recently, experiments including tritium were conducted using practical-scale adsorbers. These tests used existing cryogenic molecular sieve beds (CMSB's) which each contain about 1.6 kg of Linde 5A molecular sieve. They are part of the TSTA integrated tritium processing system. Gas was fed to each CMSB at about 13 SLPM with a nominal composition of 99% He, 0.98% H2, and 0.02% HT. In all cases, for an extended period of time, the beds allowed no detectable (via Raman spectroscopy) hydrogen isotopes to escape in the bed effluent. Thereafter, the hydrogen isotopes appeared in the bed exit with a relatively sharp breakthrough curve. This work concludes that cryogenic molecular sieve adsorption is a practical and effective means of separating low-concentration hydrogen isotopes from a helium carrier.

  16. Separating the contributions of vegetation and soil to evapotranspiration using stable isotopes

    NASA Astrophysics Data System (ADS)

    Cuntz, Matthias; Dubbert, Maren; Piayda, Arndt; Correia, Alexandra; Silva, Filipe Costa e.; Kolle, Olaf; Maguás, Cristina; Mosena, Alexander; Pereira, João S.; Rebmann, Corinna; Werner, Christiane

    2015-04-01

    Semi-arid ecosystems contribute about 40% to global net primary productivity, although water-availability limits carbon uptake. Precipitation shows periodical summer droughts and evapotranspiration accounts for up to 95% of water loss of the ecosystem. Thus functional understanding of evapotranspiration and the contributions of evaporation and transpiration from over- and understorey vegetation to water cycling in semi-arid regions is key knowledge in forest management under future climate change. Water isotopes trace water through the compartments of an ecosystem from soil and the vegetation to the atmosphere. They are used to partition evapotranspiration ET into its components evaporation E and transpiration T . The method is, however, sensitive to the knowledge of the isotopic composition of water at the evaporating sites. This led to a discussion recently about the dominance of transpiration in water loss from the terrestrial biosphere, and also how methodological problems could bias these results. Here we present observations from a Portuguese cork-oak woodland. It is a bi-layered system of widely spaced cork-oak trees and a herbaceous layer dominated by native annual forbs and grasses. Water fluxes and their isotopic compositions were measured on bare soil and vegetated plots with a transparent through-flow chamber and a water isotope laser. Soil moisture and temperature were measured in several depths and soil samples were taken for soil water isotope analysis. Based on these observations, we review current strategies of ET partitioning. We highlight pitfalls in the presented strategies and show uncertainty analyses for the different approaches. We show that the isotopic composition of evaporation is very sensitive to the sampling strategy but is described well by a steady-state formulation (Dubbert et al., J Hydrolo 2013). The isotopic composition of transpiration, on the other hand, is not in steady state, most of the time (Dubbert et al., New Phytolo 2014

  17. Gas chromatographic separation of hydrogen isotopes on columns packed with alumina, modified alumina and sol-gel alumina.

    PubMed

    Naik, Y P; Gupta, N K; Pillai, K T; Rao, G A Rama; Venugopal, V

    2012-01-06

    The stationary phase of alumina adsorbents, prepared by different chemical processes, was used to study the separation behaviour of hydrogen isotopes. Three types of alumina, obtained by conventional hydroxide route alumina coated with silicon oxide and alumina prepared by internal gelation process (IGP), were used as packing material to study the separation of HT and T(2) in a mixture at various temperatures. The conventional alumina and silicon oxide coated alumina resolved HT and T(2) at 77K temperature with different retention times. The retention times on SiO(2) coated columns were found to be higher than those of other adsorbents. However, the column filled with IGP alumina was found to be ideal for the separation of HT and T(2) at 240 K. The peaks were well resolved in less than 5 min on this column.

  18. Isotopic anomalies of Ne, Xe, and C in meteorites. I - Separation of carriers by density and chemical resistance

    NASA Technical Reports Server (NTRS)

    Ming, Tang; Lewis, Roy S.; Anders, Edward; Grady, M. M.; Wright, I. P.

    1988-01-01

    The carriers of presolar noble gases were studied by isotopically analyzing 19 separates from the Murray and Murchison C2 chondrites for Ne, Xe, C, and N. It is found that the carriers of Ne-E(H) and Xe-S are resistant to HCl, HF, boiling HClO4, and CrO3-H2SO4, and thus must be either diamond or some resistant carbide or oxide. The carrier of Ne-E(L) may be some form of amorphous carbon with delta C13 of about +340 percent. A new carbon component, C theta, found as 0.2-2-micron inclusions in Murchison spinel, is amorphous and contains little or no noble gas. A new heavy nitrogen component is found which has an abundance of about 1 ppm in the bulk meteorite, combusts at 450-500 C, and may be associated wtih isotopically normal carbon or with C-alpha.

  19. Factors influencing yield of plateletpheresis using intermittent flow cell separator.

    PubMed

    DAS, S S; Chaudhary, R K; Shukla, J S

    2005-10-01

    Platelet recovery in the recipient is influenced by the transfused dose of platelets, which in turn is dependent on the quality of single donor platelets (SDPs) in terms of platelet yield. Various donor factors such as predonation platelet count and Hemoglobin (Hb) concentration affect the platelet yield. A total of 61 plateletpheresis procedures performed on intermittent flow cell separator (MCS3p, Hemonetics) were evaluated for platelet yield. A relationship between predonation platelet count and Hb concentration with yield of platelets was studied using Pearson Correlation. The mean platelet yield was 2.9 +/- 0.64 x 10(11). While a direct relationship was observed between predonation platelet count and yield (r = 0.51, P < 0.001), no such correlation was noticed with donor Hb concentration (r = -0.05, P > 0.005). The yield was > or =3 x 10(11) in >80% of procedures when the predonation platelet count was > or =250 x 10(3)/mm. Optimization of platelet yield, which is influenced by predonation platelet count, is an emerging issue in blood transfusion services. However, further studies in this regard are needed using more advanced cell separators.

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

    SciTech Connect

    Liezers, Martin; Lehn, Scott A; Olsen, Khris B; Farmer, Orville T; Duckworth, Douglas C

    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) HNO3. No redox chemicals or acid concentration changes are required. Plutonium accumulation and release is redox dependent and controlled by the 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.

  1. Plasma centrifuge with vacuum arc discharge applied to the separation of stable isotopes

    NASA Astrophysics Data System (ADS)

    Delbosco, Edson

    1989-09-01

    The results of a vacuum-arc plasma centrifuge experiment are described. A plasma centrifuge is an apparatus where a plasma column is produced due to the interaction of an electric current with an externally applied magnetic field, vector J x vector B. Among the applications of a rotating plasma, this work deals particularly with its utilization in an isotope enrichment device. The main characteristics of the plasma produced in this experiment are presented, with special attention to the plasma column rotation and the isotope enrichment. The analysis of the results is performed using a fluid model for a completely ionized rigid body rotating plasma column in steady state equilibrium. The main results are: (1) rotation frequency of the plasma column in the range 2 x (exp 4) to 3 x 10 (exp 5) rad/s; (2) enrichment of 10 to 30 pct for the magnesium isotopes, and 290 to 490 pct for the carbon-13 isotope; (3) rigid body rotation of the plasma column only for radii smaller than the characteristic radius of the plasma column, r(sub e); (4) linear dependence of the rotation frequency upon the magnetic field strength only for r is less than r(sub e); (5) existence of an optimum value of the magnetic field for maximum enrichment; and (6) dependence of the rotation frequency upon the inverse of the atomic mass.

  2. On isotopic realizability of maps factored through a hyperplane

    NASA Astrophysics Data System (ADS)

    Melikhov, Sergey A.

    2004-08-01

    In this paper we study the isotopic realization problem, which is the question of isotopic realizability of a given (continuous) map f, that is, the possibility of a uniform approximation of f by a continuous family of embeddings g_t, t\\in \\lbrack 0,\\infty), under the condition that f is discretely realizable, that is, that there exists a uniform approximation of f by a sequence of embeddings h_n, n\\in\\mathbb N.For each n\\geqslant3 a map f\\colon S^n\\to\\mathbb R^{2n} is constructed that is discretely but not isotopically realizable and which, unlike all such previously known examples, is a locally flat topological immersion. For each n\\geqslant4 a map f\\colon S^n\\to\\mathbb R^{2n-1}\\subset\\mathbb R^{2n} is constructed that is discretely but not isotopically realizable. It is shown that for n\\equiv0,\\,1\\pmod4 any map f\\colon S^n\\to\\mathbb R^{2n-2}\\subset\\mathbb R^{2n} is isotopically realizable, and for n\\equiv2\\pmod4, so also is every map f\\colon S^n\\to\\mathbb R^{2n-3}\\subset\\mathbb R^{2n}. If n\\geqslant13 and n+1 is not a power of 2, an arbitrary map f\\colon S^n\\to\\mathbb R^{5 \\lbrack n/3 \\rbrack +3}\\subset\\mathbb R^{2n} is isotopically realizable.The main results are devoted to the isotopic realization problem for maps f of the form S^n\\stackrel{f}\\to S^n\\subset\\mathbb R^{2n}, n=2^l-1. It is established that if it has a negative solution, then the inverse images of points under the map f have a certain homology property connected with actions of the group of p-adic integers. The solution is affirmative if f is Lipschitzian and its van Kampen-Skopenkov thread has finite order. In connection with the proof the functors \\operatorname{Ext}_{\\square} and \\operatorname{Ext}_{\\bowtie} in the relative homology algebra of inverse spectra are introduced.

  3. Plutonium isotopes in the atmosphere of Central Europe: Isotopic composition and time evolution vs. circulation factors.

    PubMed

    Kierepko, Renata; Mietelski, Jerzy W; Ustrnul, Zbigniew; Anczkiewicz, Robert; Wershofen, Herbert; Holgye, Zoltan; Kapała, Jacek; Isajenko, Krzysztof

    2016-11-01

    This paper reports evidence of Pu isotopes in the lower part of the troposphere of Central Europe. The data were obtained based on atmospheric aerosol fraction samples collected from four places in three countries (participating in the informal European network known as the Ring of Five (Ro5)) forming a cell with a surface area of about 200,000km(2). We compared our original data sets from Krakow (Poland, 1990-2007) and Bialystok (Poland, 1991-2007) with the results from two other locations, Prague (Czech Republic; 1997-2004) and Braunschweig (Germany; 1990-2003) to find time evolution of the Pu isotopes. The levels of the activity concentration for (238)Pu and for ((239+240))Pu were estimated to be a few and some tens of nBqm(-3), respectively. However, we also noted some results were much higher (even about 70 times higher) than the average concentration of (238)Pu in the atmosphere. The achieved complex data sets were used to test a new approach to the problem of solving mixing isotopic traces from various sources (here up to three) in one sample. Results of our model, supported by mesoscale atmospheric circulation parameters, suggest that Pu from nuclear weapon accidents or tests and nuclear burnt-up fuel are present in the air.

  4. Stable isotope analysis of diet confirms niche separation of two sympatric species of Namib Desert lizard.

    PubMed

    Murray, Ian W; Lease, Hilary M; Hetem, Robyn S; Mitchell, Duncan; Fuller, Andrea; Woodborne, Stephan

    2016-01-01

    We used stable isotopes of carbon and nitrogen to study the trophic niche of two species of insectivorous lizards, the Husab sand lizard Pedioplanis husabensis and Bradfield's Namib day gecko living sympatrically in the Namib Desert. We measured the δ(13) C and δ(15) N ratios in lizard blood tissues with different turnover times (whole blood, red blood cells and plasma) to investigate lizard diet in different seasons. We also measured the δ(13) C and δ(15) N ratios in available arthropod prey and plant tissues on the site, to identify the avenues of nutrient movement between lizards and their prey. Through the use of stable isotope mixing models, we found that the two lizard species relied on a largely non-overlapping but seasonally variable array of arthropods: P. husabensis primarily fed on termites, beetles and wasps, while R. bradfieldi fed mainly on ants, wasps and hemipterans. Nutrients originating from C3 plants were proportionally higher for R. bradfieldi than for P. husabensis during autumn and late autumn/early winter, although not summer. Contrary to the few available data estimating the trophic transfer of nutrients in ectotherms in mixed C3 and C4 /crassulacean acid metabolism (CAM) plant landscapes, we found that our lizard species primarily acquired nutrients that originated from C4 /CAM plants. This work adds an important dimension to the general lack of studies using stable isotope analyses to estimate lizard niche partitioning and resource use.

  5. Effects of environmental and biotic factors on carbon isotopic fractionation during decomposition of soil organic matter.

    PubMed

    Wang, Guoan; Jia, Yufu; Li, Wei

    2015-06-09

    Decomposition of soil organic matter (SOM) plays an important role in the global carbon cycle because the CO2 emitted from soil respiration is an important source of atmospheric CO2. Carbon isotopic fractionation occurs during SOM decomposition, which leads to (12)C to enrich in the released CO2 while (13)C to enrich in the residual SOM. Understanding the isotope fractionation has been demonstrated to be helpful for studying the global carbon cycle. Soil and litter samples were collected from soil profiles at 27 different sites located along a vertical transect from 1200 to 4500 m above sea level (a.s.l.) in the south-eastern side of the Tibetan Plateau. Their carbon isotope ratios, C and N concentrations were measured. In addition, fiber and lignin in litter samples were also analyzed. Carbon isotope fractionation factor (α) during SOM decomposition was estimated indirectly as the slope of the relationship between carbon isotope ratios of SOM and soil C concentrations. This study shows that litter quality and soil water play a significant role in isotope fractionation during SOM decomposition, and the carbon isotope fractionation factor, α, increases with litter quality and soil water content. However, we found that temperature had no significant impact on the α variance.

  6. Effects of environmental and biotic factors on carbon isotopic fractionation during decomposition of soil organic matter

    PubMed Central

    Wang, Guoan; Jia, Yufu; Li, Wei

    2015-01-01

    Decomposition of soil organic matter (SOM) plays an important role in the global carbon cycle because the CO2 emitted from soil respiration is an important source of atmospheric CO2. Carbon isotopic fractionation occurs during SOM decomposition, which leads to 12C to enrich in the released CO2 while 13C to enrich in the residual SOM. Understanding the isotope fractionation has been demonstrated to be helpful for studying the global carbon cycle. Soil and litter samples were collected from soil profiles at 27 different sites located along a vertical transect from 1200 to 4500 m above sea level (a.s.l.) in the south-eastern side of the Tibetan Plateau. Their carbon isotope ratios, C and N concentrations were measured. In addition, fiber and lignin in litter samples were also analyzed. Carbon isotope fractionation factor (α) during SOM decomposition was estimated indirectly as the slope of the relationship between carbon isotope ratios of SOM and soil C concentrations. This study shows that litter quality and soil water play a significant role in isotope fractionation during SOM decomposition, and the carbon isotope fractionation factor, α, increases with litter quality and soil water content. However, we found that temperature had no significant impact on the α variance. PMID:26056012

  7. Effects of environmental and biotic factors on carbon isotopic fractionation during decomposition of soil organic matter

    NASA Astrophysics Data System (ADS)

    Wang, Guoan; Jia, Yufu; Li, Wei

    2015-06-01

    Decomposition of soil organic matter (SOM) plays an important role in the global carbon cycle because the CO2 emitted from soil respiration is an important source of atmospheric CO2. Carbon isotopic fractionation occurs during SOM decomposition, which leads to 12C to enrich in the released CO2 while 13C to enrich in the residual SOM. Understanding the isotope fractionation has been demonstrated to be helpful for studying the global carbon cycle. Soil and litter samples were collected from soil profiles at 27 different sites located along a vertical transect from 1200 to 4500 m above sea level (a.s.l.) in the south-eastern side of the Tibetan Plateau. Their carbon isotope ratios, C and N concentrations were measured. In addition, fiber and lignin in litter samples were also analyzed. Carbon isotope fractionation factor (α) during SOM decomposition was estimated indirectly as the slope of the relationship between carbon isotope ratios of SOM and soil C concentrations. This study shows that litter quality and soil water play a significant role in isotope fractionation during SOM decomposition, and the carbon isotope fractionation factor, α, increases with litter quality and soil water content. However, we found that temperature had no significant impact on the α variance.

  8. Factors influencing stable isotopes and growth of algae in oil sands aquatic reclamation.

    PubMed

    Boutsivongsakd, Monique; Farwell, Andrea J; Chen, Hao; Dixon, D George

    2015-01-01

    Previous studies reported (15)N enrichment of biota in reclamation wetlands that contain oil sands processed material (e.g., processed water and tailings); however, there is little information on the factors controlling (15)N enrichment in these systems. In this microcosm study, the aim was to examine stable C and N isotopes and growth (chlorophyll a [chl a] and dry weight) of algae as a function of exposure to different sources and concentrations of water-soluble fractions (WSF) derived from tailings. Two sources of tailings including mature fine tailings (MFT) and consolidated tailings (CT) and peat-mineral overburden were utilized to generate separate WSF that differed in water quality. In general, there was (15)N enrichment of filamentous algae along the increasing gradient of WSF/nutrient concentrations in both CT and peat microcosms, and among the different sources, algae were more (15)N enriched in CT WSF than in peat WSF. Growth of filamentous algae was inhibited at higher WSF concentrations, possibly due to reduced light availability at elevated levels of fine clay particles in MFT microcosms and colored dissolved organic carbon (DOC) in peat microcosms. Filamentous algae displayed lower biomass and (15)N depletion in 100% peat WSF. This study indicated that both the quality (source) and quantity of WSF affected algal growth and directly and/or indirectly influenced δ(15)N of algae. The distinct (15)N enrichment of primary producers derived from tailings suggest that stable N isotopes might be useful to trace exposure to oil sands processed material in biota that utilize these resources in reclaimed systems constructed with tailings or natural systems that receive tailings dyke seepage.

  9. Lead isotope systematics of some Apollo 17 soils and some separated components from 76501

    NASA Technical Reports Server (NTRS)

    Church, S. E.; Tilton, G. R.

    1974-01-01

    Isotopic lead data from bulk samples of Apollo 17 soils were analyzed, and they define a chord in a concordia diagram, showing the presence of a component or components containing excess radiogenic lead with Pb-207/Pb-206 equal to about 1.32. The chord is distinctly different from the cataclysm chord, for which Pb-207/Pb-206 is approximately 1.45. Nitric acid analysis of plagioclase indicates lead ages of around 4.35 AE, in agreement with previous findings. Agglutinates from soil 76501,34 show loss of approximately 15% of lead.

  10. 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.

  11. Trophic discrimination factors of stable carbon and nitrogen isotopes in hair of corn fed wild boar.

    PubMed

    Holá, Michaela; Ježek, Miloš; Kušta, Tomáš; Košatová, Michaela

    2015-01-01

    Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissue- and species-specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ13C) and nitrogen (Δ15N) isotopes were determined from hair samples. The mean Δ13C and Δ15N in wild boar hair were -2.3‰ and +3.5‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d(-1). Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types.

  12. Trophic Discrimination Factors of Stable Carbon and Nitrogen Isotopes in Hair of Corn Fed Wild Boar

    PubMed Central

    Holá, Michaela; Ježek, Miloš; Kušta, Tomáš; Košatová, Michaela

    2015-01-01

    Stable isotope measurements are increasingly being used to gain insights into the nutritional ecology of many wildlife species and their role in ecosystem structure and function. Such studies require estimations of trophic discrimination factors (i.e. differences in the isotopic ratio between the consumer and its diet). Although trophic discrimination factors are tissue- and species- specific, researchers often rely on generalized, and fixed trophic discrimination factors that have not been experimentally derived. In this experimental study, captive wild boar (Sus scrofa) were fed a controlled diet of corn (Zea mays), a popular and increasingly dominant food source for wild boar in the Czech Republic and elsewhere in Europe, and trophic discrimination factors for stable carbon (Δ13C) and nitrogen (Δ15N) isotopes were determined from hair samples. The mean Δ13C and Δ15N in wild boar hair were –2.3 ‰ and +3.5 ‰, respectively. Also, in order to facilitate future derivations of isotopic measurements along wild boar hair, we calculated the average hair growth rate to be 1.1 mm d-1. Our results serve as a baseline for interpreting isotopic patterns of free-ranging wild boar in current European agricultural landscapes. However, future research is needed in order to provide a broader understanding of the processes underlying the variation in trophic discrimination factors of carbon and nitrogen across of variety of diet types. PMID:25915400

  13. Hydrogen isotope separation in carbon nanotubes: calculation of coupled rotational and translational States at high densities.

    PubMed

    Garberoglio, Giovanni; Johnson, J Karl

    2010-03-23

    The effect of the quantized rotational degrees of freedom of hydrogen on the adsorption and sieving properties in carbon nanotubes is studied using computer simulations. We have developed a highly efficient multiple timestep algorithm for hybrid Monte Carlo sampling of quantized rotor configurations and extended the grand canonical Boltzmann bias method to rigid linear molecules. These new computational tools allow us to calculate accurately the quantum sieving selectivities for cases of extreme two-dimensional confinement as a function of pressure. The para-T2/para-H2 selectivity at 20 K is analyzed as a function of the tube diameter and the density of adsorbed hydrogen. Extraordinarily high selectivities, up to 2.6 x 10(8), are observed in the narrowest nanotube. The quantized nature of the rotational degrees of freedom is found to dramatically affect adsorption and selectivity for hydrogen isotopes adsorbed in very narrow nanotubes. The T2/H2 zero-pressure selectivity increases from 2.4 x 10(4) to 1.7 x 10(8) in the (3,6) nanotube at 20 K when quantum rotations are accounted for. The isotopic selectivity is found to increase with pressure, tending to a constant value at saturation. A simplified mean-field model is used to discuss the origin of this behavior.

  14. Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment

    NASA Astrophysics Data System (ADS)

    Alperin, M. J.; Blair, N. E.; Albert, D. B.; Hoehler, T. M.; Martens, C. S.

    1992-09-01

    The carbon isotopic composition of methane produced in anoxic marine sediment is controlled by four factors: (1) the pathway of methane formation, (2) the isotopic composition of the methanogenic precursors, (3) the isotope fractionation factors for methane production, and (4) the isotope fractionation associated with methane oxidation. The importance of each factor was evaluated by monitoring stable carbon isotope ratios in methane produced by a sediment microcosm. Methane did not accumulate during the initial 42-day period when sediment contained sulfate, indicating little methane production from "noncompetitive" substrates. Following sulfate depletion, methane accumulation proceeded in three distinct phases. First, CO2 reduction was the dominant methanogenic pathway and the isotopic composition of the methane produced ranged from -80 to -94‰. The acetate concentration increased during this phase, suggesting that acetoclastic methanogenic bacteria were unable to keep pace with acetate production. Second, acetate fermentation became the dominant methanogenic pathway as bacteria responded to elevated acetate concentrations. The methane produced during this phase was progressively enriched in 13C, reaching a maximum δ13C value of -42‰. Third, the acetate pool experienced a precipitous decline from >5 mM to <20 μM and methane production was again dominated by CO2 reduction. The δ13C of methane produced during this final phase ranged from -46 to -58‰. Methane oxidation concurrent with methane production was detected throughout the period of methane accumulation, at rates equivalent to 1 to 8% of the gross methane production rate. Thus methane oxidation was too slow to have significantly modified the isotopic signature of methane. A comparison of microcosm and field data suggests that similar microbial interactions may control seasonal variability in the isotopic composition of methane emitted from undisturbed Cape Lookout Bight sediment.

  15. Factors that control the stable carbon isotopic composition of methane produced in an anoxic marine sediment

    NASA Technical Reports Server (NTRS)

    Alperin, M. J.; Blair, Neal E.; Albert, D. B.; Hoehler, T. M.; Martens, C. S.

    1993-01-01

    The carbon isotopic composition of methane produced in anoxic marine sediment is controlled by four factors: (1) the pathway of methane formation, (2) the isotopic composition of the methanogenic precursors, (3) the isotope fractionation factors for methane production, and (4) the isotope fractionation associated with methane oxidation. The importance of each factor was evaluated by monitoring stable carbon isotope ratios in methane produced by a sediment microcosm. Methane did not accumulate during the initial 42-day period when sediment contained sulfate, indicating little methane production from 'noncompetitive' substrates. Following sulfate depletion, methane accumulation proceeded in three distinct phases. First, CO2 reduction was the dominant methanogenic pathway and the isotopic composition of the methane produced ranged from -80 to -94 per thousand. The acetate concentration increased during this phase, suggesting that acetoclastic methanogenic bacteria were unable to keep pace with acetate production. Second, acetate fermentation became the dominant methanogenic pathway as bacteria responded to elevated acetate concentrations. The methane produced during this phase was progressively enriched in C-13, reaching a maximum delta(C-13) value of -42 per thousand. Third, the acetate pool experienced a precipitous decline from greater than 5 mM to less than 20 micro-M and methane production was again dominated by CO2 reduction. The delta(C-13) of methane produced during this final phase ranged from -46 to -58 per thousand. Methane oxidation concurrent with methane production was detected throughout the period of methane accumulation, at rates equivalent to 1 to 8 percent of the gross methane production rate. Thus methane oxidation was too slow to have significantly modified the isotopic signature of methane. A comparison of microcosm and field data suggests that similar microbial interactions may control seasonal variability in the isotopic composition of methane

  16. Development of a fully automated open-column chemical-separation system—COLUMNSPIDER—and its application to Sr-Nd-Pb isotope analyses of igneous rock samples

    NASA Astrophysics Data System (ADS)

    Miyazaki, Takashi; Vaglarov, Bogdan Stefanov; Takei, Masakazu; Suzuki, Masahiro; Suzuki, Hiroaki; Ohsawa, Kouzou; Chang, Qing; Takahashi, Toshiro; Hirahara, Yuka; Hanyu, Takeshi; Kimura, Jun-Ichi; Tatsumi, Yoshiyuki

    A fully automated open-column resin-bed chemical-separation system, named COLUMNSPIDER, has been developed. The system consists of a programmable micropipetting robot that dispenses chemical reagents and sample solutions into an open-column resin bed for elemental separation. After the initial set up of resin columns, chemical reagents, and beakers for the separated chemical components, all separation procedures are automated. As many as ten samples can be eluted in parallel in a single automated run. Many separation procedures, such as radiogenic isotope ratio analyses for Sr and Nd, involve the use of multiple column separations with different resin columns, chemical reagents, and beakers of various volumes. COLUMNSPIDER completes these separations using multiple runs. Programmable functions, including the positioning of the micropipetter, reagent volume, and elution time, enable flexible operation. Optimized movements for solution take-up and high-efficiency column flushing allow the system to perform as precisely as when carried out manually by a skilled operator. Procedural blanks, examined for COLUMNSPIDER separations of Sr, Nd, and Pb, are low and negligible. The measured Sr, Nd, and Pb isotope ratios for JB-2 and Nd isotope ratios for JB-3 and BCR-2 rock standards all fall within the ranges reported previously in high-accuracy analyses. COLUMNSPIDER is a versatile tool for the efficient elemental separation of igneous rock samples, a process that is both labor intensive and time consuming.

  17. Recent developments of the ion sources at Tri University Meson Factory/Isotope Separator and ACcelerator Facility.

    PubMed

    Bricault, P G; Ames, F; Dombsky, M; Labrecque, F; Lassen, J; Mjos, A; Minor, G; Tigelhoefer, A

    2012-02-01

    This paper describes the recent progresses concerning the on-line ion source at the Tri University Meson Factory/Isotope Separator and ACcelerator (TRIUMF/ISAC) Radioactive Ion-Beam Facility; description of the new design of the surface-ion-source for improved stability of the beam intensity, description of the transport path to the east target station at ISAC, description of the new brazing techniques that solved recurrent problems with water leaks on the target/ion source assembly in the vacuum system, finally, recent developments concerning the Forced Electron Beam Induced Arc Discharge (FEBIAD) ion source are reported. In particular, a study on the effect of the plasma chamber volume on the ionization efficiency was completed.

  18. 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.

  19. Key factors of eddy current separation for recovering aluminum from crushed e-waste.

    PubMed

    Ruan, Jujun; Dong, Lipeng; Zheng, Jie; Zhang, Tao; Huang, Mingzhi; Xu, Zhenming

    2017-02-01

    Recovery of e-waste in China had caused serious pollutions. Eddy current separation is an environment-friendly technology of separating nonferrous metallic particles from crushed e-waste. However, due to complex particle characters, separation efficiency of traditional eddy current separator was low. In production, controllable operation factors of eddy current separation are feeding speed, (ωR-v), and Sp. There is little special information about influencing mechanism and critical parameters of these factors in eddy current separation. This paper provided the special information of these key factors in eddy current separation of recovering aluminum particles from crushed waste refrigerator cabinets. Detachment angles increased as the increase of (ωR-v). Separation efficiency increased with the growing of detachment angles. Aluminum particles were completely separated from plastic particles in critical parameters of feeding speed 0.5m/s and detachment angles greater than 6.61deg. Sp/Sm of aluminum particles in crushed waste refrigerators ranged from 0.08 to 0.51. Separation efficiency increased as the increase of Sp/Sm. This enlightened us to develop new separator to separate smaller nonferrous metallic particles in e-waste recovery. High feeding speed destroyed separation efficiency. However, greater Sp of aluminum particles brought positive impact on separation efficiency. Greater Sp could increase critical feeding speed to offer greater throughput of eddy current separation. This paper will guide eddy current separation in production of recovering nonferrous metals from crushed e-waste.

  20. Baseflow separation in a premontane transitional rainforest using stable isotope techniques

    NASA Astrophysics Data System (ADS)

    Miller, G. R.; DuMont, A.; Roark, E.; Cahill, A. T.; Brumbelow, J. K.

    2013-12-01

    Hydrologic, geologic, and biologic processes are critical to understanding the ecosystem in the tropical premontane transitional forests of Costa Rica. Precipitation is significantly lower during the dry season, and incoming rainfall can be completely intercepted and re-evaporated by the canopy during light events. These canopy processes can affect the rates of runoff and infiltration by changing the quantity and timing of rainfall reaching the ground surface. However, the resulting partitioning of stream water sources between event-water and baseflow from groundwater is not well quantified due to limited accessibility and complex subsurface conditions. This study focuses on research conducted at the Texas A&M Soltis Center for Education and Research, near San Ramón, Costa Rica. We have monitored a 2.2 ha watershed there, measuring precipitation and transpiration rates for over two years, and groundwater levels and stream flow rates for nearly one year. Precipitation rates for the watershed averaged 4.4 m/yr since 2010. Stream flow (runoff, spring flow, and baseflow) averaged 0.09 m^3/sec during the 2012-2013 wet seasons. At 1.2 mm/day, transpiration was a relatively minor component of the water budget. Over a 40-day span during summer 2013, we collected a combination of daily and rain-event based samples from locations throughout the watershed. Sources included: the main stream and two small tributaries, groundwater from piezometers, pore water from suction lysimeters, throughfall and stemflow from under canopy collection systems, and xylem water from 8 tree species across the watershed. We then measured stable isotope fractions (δ18O and δD) in the water using a Picarro L2120i CRDS. Isotope ratios for all surface water averaged -5.50‰ for δ18O and -28.00‰ for δD, while that measured under baseflow conditions were -5.45‰ for δ18O and -29.18‰ for δD. These results indicate that baseflow is the dominate source of stream water even in the wet season

  1. Separating Continental Mineral Dust from Cosmic Dust using Platinum Group Element Concentrations and Osmium Isotopes in Ancient Polar Ice

    NASA Astrophysics Data System (ADS)

    Seo, J. H.; Jackson, B.; Osterberg, E. C.; Sharma, M.

    2015-12-01

    The platinum group element (PGEs: Pt, Pd, Rh, Ir, Os, and Ru) accumulation in ancient polar archives have been argued to trace cosmic dust and "smoke" from larger meteors but the PGE concentration data lack specificity. For example, the extent to which the terrestrial volcanism/dust has contributed to the PGE inventory of polar ice cannot be readily evaluated. Since the Os isotope compositions (187Os/188Os ratio) of the terrestrial and extraterrestrial sources are distinctly different from each other, the PGE concentrations when combined with Os isotope composition have the potential to untangle contributions from these sources. Platinum group element concentration determinations in polar ice cores are highly challenging due to their extremely low concentrations (down to 10-15 g/g or fg/g). Here, a new procedure is presented that allows PGEs and Os isotope compositions to be determined from a ~50 g sample of polar ice. Decontaminated ice-melt is spiked with 101Ru, 106Pd, 190Os, 191Ir, and 198Pt and frozen at -20 °C in quartz-glass ampoules. A mixture of purified HNO3 and H2O2 is then added and the sample is heated to 300 °C at 128bar using a High Pressure Asher. This allows all spikes to be equilibrated with the sample PGEs and all Os species are oxidized to OsO4. The resulting OsO4 is extracted using distillation, purified, and measured using negative thermal ionization mass spectrometry. PGEs are then separated and purified using two stage column chromatography and their concentrations determined by isotope dilution using a triple quadruople inductively coupled plasma mass spectrometer coupled to an Apex de-solvation nebulizer. The developed method was applied to modern Greenland firn and snow. The PGE concentrations of the firn are 4.0 fg/g for Ir, 20 fg/g for Ru, 590 fg/g for Pt, 38 fg/g for Pd, and 1.3 fg/g for Os, while those of the snow are 3.0 fg/g for Ir, 53 fg/g for Ru, 360 fg/g for Pt, 32 fg/g for Pd, and 0.4 fg/g for Os, respectively. A comparison

  2. Separation of drainage runoff during rainfall-runoff episodes using the stable isotope method and drainage water temperature

    NASA Astrophysics Data System (ADS)

    Zajíček, Antonín; Kvítek, Tomáš; Pomije, Tomáš

    2014-05-01

    Stabile isotopes of 2H 18O and drainage water temperature were used as natural tracers for separation rainfall-runoff event hydrograph on several tile drained catchments located in Bohemian-Moravian Highland, Czech Republic. Small agricultural catchments with drainage systems built in slopes are typical for foothill areas in the Czech and Moravian highland. Often without permanent surface runoff, the drainage systems represent an important portion of runoff and nitrogen leaching out of the catchment. The knowledge of the drainage runoff formation and the origin of its components are prerequisites for formulation of measures leading to improvement of the drainage water quality and reduction of nutrient leaching from the drained catchments. The results have proved presence of event water in the drainage runoff during rainfall-runoff events. The proportion of event water observed in the drainage runoff varied between 15 - 60 % in the summer events and 0 - 50 % in winter events, while the sudden water temperature change was between 0,1 - 4,2 °C (2 - 35 %). The comparison of isotope separation of the drainage runoff and monitoring the drainage water temperature have demonstrated that in all cases of event water detected in the runoff, a rapid change in the drainage water temperature was observed as well. The portion of event water in the runoff grows with the growing change in water temperature. Using component mixing model, it was demonstrated that water temperature can be successfully used at least as a qualitative and with some degree of inaccuracy as a quantitative tracer as well. The drawback of the non-conservative character of this tracer is compensated by both its economic and technical accessibility. The separation results also resemble results of separations at small streams. Together with a similarly high speed of the discharge reaction to beginning of precipitation, it is obvious that the mechanism of surface runoff formation and drainage runoff formation

  3. Diffusion as a Rate Limiting Factor on the Evolution of Strontium Isotope Ratios in Fractured Rock

    NASA Astrophysics Data System (ADS)

    Johnson, E. G.; Holt, R. M.; McLing, T. L.

    2002-12-01

    In recent years, several approaches have been developed to model the evolution of strontium isotope ratios (87Sr/86Sr) in porous media. In fractured rock, however, diffusion limits the rates of reaction between mobile water and mineral surfaces inside fracture-bounded blocks. Diffusion can limit transfer of fluids with differing isotopic ratios between the mobile and immobile zones leading to longer equilibration times. We develop a diffusion-based mathematical approach for modeling the evolution of ratios that includes sorption, ion exchange, and dissolution in fracture bounded blocks of multiple sizes. Traditional models employing isotopic ratios with the advection-dispersion equation are unable to incorporate diffusion because they are limited by the structure of their equation. Modeling the individual isotopic species separately accounts for the effects of diffusion. The general governing equation is robust in that it does not assume chemical equilibrium reactions. Special cases show the importance of diffusion-limited mass transfer on the evolution of isotopes ratios in fractured rock.

  4. Compositional and isotopic diversity in MORB crystal cargoes: the differing influence of crustal and mantle processes on separate phase populations

    NASA Astrophysics Data System (ADS)

    Winpenny, B.; Maclennan, J.

    2010-12-01

    trace elements and Sr and O isotope ratios in compositionally zoned crystals. By comparing the known liquid compositions of Krafla and Borgarhraun with feldspar trace element and isotopic data, we aim to determine whether the plagioclase crystals are of a) magmatic or b) hydrothermal origin, and if magmatic, whether the crystals are cognate to the carrier melt or of xenocrystic origin. Preliminary O and Sr isotope data suggest that a sub-population of plagioclase crystals from both flows has undergone direct hydrothermal interaction, with others having crystallised from melts contaminated by altered crustal material. Additionally, some of the aspects of the current plagioclase dataset can be explained by concurrent mixing and crystallisation of variable primary mantle melt compositions, in sympathy with the clinopyroxene and olivine data. The contrasting and possibly diverse origins for the chemical and isotopic heterogeneity in separate crystal phase populations in these basaltic flows highlight the need for careful characterisation of individual crystal phases when making inferences from bulk isotopic or chemical analyses on MORB phenocrysts.

  5. Distinctive diet-tissue isotopic discrimination factors derived from the exclusive bamboo-eating giant panda.

    PubMed

    Han, Han; Wei, Wei; Nie, Yonggang; Zhou, Wenliang; Hu, Yibo; Wu, Qi; Wei, Fuwen

    2016-11-01

    Stable isotope analysis is very useful in animal ecology, especially in diet reconstruction and trophic studies. Differences in isotope ratios between consumers and their diet, termed discrimination factors, are essential for studies of stable isotope ecology and are species-specific and tissue-specific. Given the specialized bamboo diet and clear foraging behavior, here, we calculated discrimination factors for carbon and nitrogen isotopes from diet to tissues (tooth enamel, hair keratin and bone collagen) for the giant panda (Ailuropoda melanoleuca), a species derived from meat-eating ancestors. Our results showed that carbon discrimination factor obtained from giant panda tooth enamel (ε (13) Cdiet-enamel = 10.0‰) and nitrogen discrimination factors from hair keratin (Δ(15) Ndiet-hair = 2.2‰) and bone collagen (Δ(15) Ndiet-collagen = 2.3‰) were lower, and carbon discrimination factors from hair keratin (Δ(13) Cdiet-hair = 5.0‰) and bone collagen (Δ(13) Cdiet-collagen = 6.1‰) were higher than those of other mammalian carnivores, omnivores and herbivores. Such distinctive values are likely the result of a low-nutrient and specialized bamboo diet, carnivore-like digestive system and exceptionally low metabolism in giant pandas.

  6. Pygmy dipole strength close to particle-separation energies --The case of the Mo isotopes

    NASA Astrophysics Data System (ADS)

    Rusev, G.; Grosse, E.; Erhard, M.; Junghans, A.; Kosev, K.; Schilling, K.-D.; Schwengner, R.; Wagner, A.

    2006-03-01

    The distribution of electromagnetic dipole strength in 92, 98, 100Mo has been investigated by photon scattering using bremsstrahlung from the new ELBE facility. The experimental data for well-separated nuclear resonances indicate a transition from a regular to a chaotic behaviour above 4MeV of excitation energy. As the strength distributions follow a Porter-Thomas distribution much of the dipole strength is found in weak and in unresolved resonances appearing as fluctuating cross section. An analysis of this quasi-continuum --here applied to nuclear resonance fluorescence in a novel way-- delivers dipole strength functions, which are combining smoothly to those obtained from (γ, n) data. Enhancements at 6.5MeV and at ˜ 9MeV are linked to the pygmy dipole resonances postulated to occur in heavy nuclei.

  7. Towards high precision measurements of nuclear g-factors for the Be isotopes

    NASA Astrophysics Data System (ADS)

    Takamine, A.; Wada, M.; Okada, K.; Ito, Y.; Schury, P.; Arai, F.; Katayama, I.; Imamura, K.; Ichikawa, Y.; Ueno, H.; Wollnik, H.; Schuessler, H. A.

    2016-06-01

    We describe the present status of future high-precision measurements of nuclear g-factors utilizing laser-microwave double and laser-microwave-rf triple resonance methods for online-trapped, laser-cooled radioactive beryllium isotope ions. These methods have applicability to other suitably chosen isotopes and for beryllium show promise in deducing the hyperfine anomaly of 11Be with a sufficiently high precision to study the nuclear magnetization distribution of this one-neutron halo nucleus in a nuclear-model-independent manner.

  8. Proceedings of the XVIIth International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS2015), Grand Rapids, MI, U.S.A., 11-15 May 2015

    NASA Astrophysics Data System (ADS)

    Bollen, Georg; Mittig, Wolfgang; Morrissey, Dave; Schwarz, Stefan; Villari, Antonio

    2016-06-01

    The 17th International Conference on Electromagnetic Isotope Separators and Related Topics (EMIS-2015) was held in Grand Rapids, Michigan, in the United States, from May 11th to 15th, 2015. The EMIS-2015 conference was hosted by Michigan State University. The present volume contains the proceedings of the event.

  9. The Precise Determination of Cd Isotope Ratio in Geological Samples by MC-ICP-MS with Ion Exchange Separation

    NASA Astrophysics Data System (ADS)

    Du, C.; Hu, S.; Wang, D.; Jin, L.; Guo, W.

    2014-12-01

    Cadmium (Cd) is a trace element which occurs at μg g-1 level abundances in the crust. Cd isotopes have great prospects in the study of the cosmogony, the trace of anthropogenic sources, the micronutrient cycling and the ocean productivity. This study develops an optimized technique for the precise and accurate determination of Cd isotopic compositions. Cd was separated from the matrix by elution with AG-MP-1 anionic exchange chromatographic resin. The matrix elements (K, Na, Ca, Al, Fe, and Mg etc.), polyatomic interfered elements (Ge, Ga, Zr, Nb, Ru, and Mo), and isobaric interfered elements (In, Pd and most of Sn) were eluted using HCl with gradient descent concentrations (2, 0.3, 0.06, 0.012 and 0.0012 mol L-1). The same elution procedure was repeated to eliminate the residuel Sn (Sn/Cd < 0.018). The collected Cd was analyzed using MC-ICP-MS, in which the instrumental mass fractionation was controlled by a "sample-standard bracketing" technique. The recovery of Cd larger than 96.85%, and the δ114/110Cd are in the range of -1.43~+0.20‰ for ten geological reference materials (GSD-3a, GSD-5a, GSD-7a, GSD-6, GSD-9, GSD-10, GSD-11, GSD-12, GSD-23, and GSS-1). The δ114/110Cd obtained for GSS-1 soil sample relative to the NIST SRM 3108 Cd solution was 0.20, which was coherent with the literature values (0.08±0.23). This method had a precision of 0.001~0.002% (RSD), an error range of 0.06~0.14 (δ114/110Cd, 2σ), and a long-term reproducibility of 0.12 (δ114/110Cd, 2σ).

  10. Experimental equipment for an advanced ISOL facility[Isotope Separation On-Line Facility

    SciTech Connect

    Baktash, C.; Lee, I.Y.; Rehm, K.E.

    1999-03-01

    This report summarizes the proceedings and recommendations of the Workshop on the Experimental Equipment for an Advanced ISOL Facility which was held at Lawrence Berkeley National Laboratory on July 22--25, 1998. The purpose of this workshop was to discuss the performance requirements, manpower and cost estimates, as well as a schedule of the experimental equipment needed to fully exploit the new physics which can be studied at an advanced ISOL facility. An overview of the new physics opportunities that would be provided by such a facility has been presented in the White Paper that was issued following the Columbus Meeting. The reactions and experimental techniques discussed in the Columbus White Paper served as a guideline for the formulation of the detector needs at the Berkeley Workshop. As outlined a new ISOL facility with intense, high-quality beams of radioactive nuclei would provide exciting new research opportunities in the areas of: the nature of nucleonic matter; the origin of the elements; and tests of the Standard Model. After an introductory section, the following equipment is discussed: gamma-ray detectors; recoil separators; magnetic spectrographs; particle detectors; targets; and apparatus using non-accelerated beams.

  11. Cr isotope fractionation factors for Cr(VI) reduction by a metabolically diverse group of bacteria

    NASA Astrophysics Data System (ADS)

    Basu, Anirban; Johnson, Thomas M.; Sanford, Robert A.

    2014-10-01

    Reduction of Cr(VI) is an important process that determines the geochemical behavior, mobility and bioavailability of Cr in both terrestrial and marine environments. Many metabolically diverse microorganisms possess Cr(VI) reduction capacity. Cr(VI) reduction fractionates Cr isotopes and thus 53Cr/52Cr ratios can be used to monitor Cr(VI) reduction and redox conditions. The magnitude of isotopic fractionation (ε) for a variety of microbial reduction mechanisms must be known for accurate interpretation of observed shifts in 53Cr/52Cr ratios. We determined isotopic fractionation factors for Cr(VI) reduction by metal reducers Geobacter sulfurreducens and Shewanella sp. strain NR, a denitrifying soil bacterium Pseudomonas stutzeri DCP-Ps1, and a sulfate reducer Desulfovibrio vulgaris. All bacteria investigated in this study produced significant Cr isotope fractionation. The fractionation (ε) for G. sulfurreducens, Shewanella sp. (NR), P. stutzeri DCP-Ps1, and D. vulgaris were -3.03‰ ± 0.12‰, -2.17‰ ± 0.22‰, -3.14‰ ± 0.13‰, and -3.01‰ ± 0.11‰, respectively. Despite differences in microbial strains in this study, the ε did not vary significantly except for Shewanella sp. (NR). Our results suggest that strong isotopic fractionation is induced during Cr(VI) reduction under electron donor poor (∼300 μM) conditions.

  12. Team resource management trainer's manual for the atomic vapor laser isotope separation program

    SciTech Connect

    Bennett, Tom

    1998-03-13

    High reliability organizations do exist. They have been defined as those organizations that conduct thousands of high-consequence operations a year, essentially error-free. Naval air carriers, air traffic control, and commercial aviation are some of these kinds of organizations. How did they get that way? What kinds of people staff them? Can we become a high reliability organization? This workshop will look at these questions. When we are done, it will be up to you to determine whether we have the right stuff. There are six goals for this workshop: Describe Team Resource Management and its purpose; Describe Performance Shaping Factors (PSFs) and their role in predicting and managing team performance and errors; Describe the principles for managing human error; Describe TRM's 12 rules-of-thumb (the "Dirty Dozen") and use of safety nets; Conduct Operational Risk Management (ORM); Demonstrate ways to keep TRM working.

  13. Physiological and environmental factors related to carbon isotopic variations in mollusc shell carbonate

    SciTech Connect

    Krantz, D.E.; Williams, D.F.; Jones, D.S.

    1985-01-01

    The carbon isotopic composition of mollusc shell carbonate has been used as a general environmental indicator in numerous studies, but relatively little is known of the factors which affect within-shell variation. Primary control of delta/sup 13/C values in shell carbonate comes from the dissolved bicarbonate source, particularly as related to marine versus fresh water. Present models explain cyclic variations in the delta/sup 13/C profiles of mollusc shells due to upwelling, phytoplankton productivity and stratification, disequilibrium with rapid shell growth, and infaunal versus epifaunal habitat. Carbon and oxygen isotopic profiles in this study were obtained from specimens of Spisula solidissima (surf clam) and Placopecten magellanicus (sea scallop) collected alive from 14 to 57 m water depths off the Virginia coast. Three main factors appear to affect the delta/sup 13/C profiles in these specimens. Isotopically light values commonly associated with the spring and occasionally the fall correspond with seasonal phytoplankton productivity. A significant negative delta/sup 13/C offset of the infaunal Spisula relative to the epifaunal Placopecten probably relates to the inclusion of isotopically more negative pore-water bicarbonate by Spisula. Additionally, occasional transient spikes in both the delta/sup 18/O and delta/sup 13/C profiles correspond to intrusion of reduced-salinity water.

  14. Sludge pretreatment chemistry evaluation: Enhanced sludge washing separation factors

    SciTech Connect

    Colton, N.G.

    1995-03-01

    This report presents the work conducted in Fiscal Year 1994 by the Sludge Pretreatment Chemistry Evaluation Subtask for the Tank Waste Remediation System (TWRS) Tank Waste Treatment Science Task. The main purpose of this task, is to provide the technical basis and scientific understanding to support TWRS baseline decisions and actions, such as the development of an enhanced sludge washing process to reduce the volume of waste that will require high-level waste (HLW) vitrification. One objective within the Sludge Pretreatment Chemistry Evaluation Subtask was to establish wash factors for various SST (single-shell tank) sludges. First, analytical data were compiled from existing tank waste characterization reports. These data were summarized on tank-specific worksheets that provided a uniform format for reviewing and comparing data, as well as the means to verify whether the data set for each tank was complete. Worksheets were completed for 27 SST wastes. The analytical water wash data provided tank-specific information about the fraction of each component that dissolves with water, i.e., an estimate of tank-specific wash factors for evaluating tank-by-tank processing. These wash data were then used collectively to evaluate some of the wash factors that are assumed for the overall SST waste inventory; specifically, wash factors for elements that would be found primarily in sludges. The final step in this study was to incorporate the characterization and wash factor data into a spreadsheet that provides insight into the effect of enhanced sludge washing on individual tank sludges as well as for groups of sludges that may be representative of different waste types. Spreadsheet results include the estimated mass and percentage of each element that would be removed with washing and leaching. Furthermore, estimated compositions are given of the final wash and leach streams and residual solids, in terms of both concentration and dry weight percent.

  15. Team resource management participant's handbook for the atomic vapor laser isotope separation program

    SciTech Connect

    Bennett, Tom

    1998-05-01

    The goal of any operation is to complete tasks efficiently and effectively. Working safely is completely consistent with efficient, reliable operations. Working in an unsafe manner is not effective or ultimately efficient. If someone is hurt, work stops. Following the steps advocated by Team Resource Management (TRM) leads to more safe, efficient, effective work habits. TRM is a method used by teams (i.e., leaders and workers) to conduct technical business. It is used by the aviation industry to improve reliability and safety through formalizing the way it does business. High reliability organizations do exist. They conduct thousands of high-consequence operations a year, essentially error-free. Naval air carriers, air traffic control, and commercial aviation are some of these kinds of organizations. How did they get that way? What kinds of people staff them? Can we become a high reliability organization? This workshop will look at these questions. When we are done, it will be up to you to determine if we have the right stuff. The goals of this workshop are to: Describe Team Resource Management and its purpose; Describe Performance Shaping Factors (PSFs) and their role in predicting and managing team performance and errors; Describe the principles for managing human error; Describe TRM's 12 rules-of-thumb (the "Dirty Dozen") and use of safety nets; Conduct Operational Risk Management (ORM); Demonstrate ways to keep TRM working.

  16. Long-term fertilization alters chemically-separated soil organic carbon pools: Based on stable C isotope analyses

    NASA Astrophysics Data System (ADS)

    Dou, Xiaolin; He, Ping; Cheng, Xiaoli; Zhou, Wei

    2016-01-01

    Quantification of dynamics of soil organic carbon (SOC) pools under the influence of long-term fertilization is essential for predicting carbon (C) sequestration. We combined soil chemical fractionation with stable C isotope analyses to investigate the C dynamics of the various SOC pools after 25 years of fertilization. Five types of soil samples (0–20, 20–40 cm) including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, IN; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into recalcitrant and labile fractions, and the fractions were analysed for C content, C:N ratios, δ13C values, soil C and N recalcitrance indexes (RIC and RIN). Chemical fractionation showed long-term MNPK fertilization strongly increased the SOC storage in both soil layers (0–20 cm = 1492.4 gC m2 and 20–40 cm = 1770.6 gC m2) because of enhanced recalcitrant C (RC) and labile C (LC). The 25 years of inorganic fertilizer treatment did not increase the SOC storage mainly because of the offsetting effects of enhanced RC and decreased LC, whereas no clear SOC increases under the SNPK fertilization resulted from the fast decay rates of soil C.

  17. Long-term fertilization alters chemically-separated soil organic carbon pools: Based on stable C isotope analyses

    PubMed Central

    Dou, Xiaolin; He, Ping; Cheng, Xiaoli; Zhou, Wei

    2016-01-01

    Quantification of dynamics of soil organic carbon (SOC) pools under the influence of long-term fertilization is essential for predicting carbon (C) sequestration. We combined soil chemical fractionation with stable C isotope analyses to investigate the C dynamics of the various SOC pools after 25 years of fertilization. Five types of soil samples (0–20, 20–40 cm) including the initial level (CK) and four fertilization treatments (inorganic nitrogen fertilizer, IN; balanced inorganic fertilizer, NPK; inorganic fertilizer plus farmyard manure, MNPK; inorganic fertilizer plus corn straw residue, SNPK) were separated into recalcitrant and labile fractions, and the fractions were analysed for C content, C:N ratios, δ13C values, soil C and N recalcitrance indexes (RIC and RIN). Chemical fractionation showed long-term MNPK fertilization strongly increased the SOC storage in both soil layers (0–20 cm = 1492.4 gC m2 and 20–40 cm = 1770.6 gC m2) because of enhanced recalcitrant C (RC) and labile C (LC). The 25 years of inorganic fertilizer treatment did not increase the SOC storage mainly because of the offsetting effects of enhanced RC and decreased LC, whereas no clear SOC increases under the SNPK fertilization resulted from the fast decay rates of soil C. PMID:26750143

  18. Characterization of Diesel Fuel by Chemical Separation Combined with Capillary Gas Chromatography (GC) Isotope Ratio Mass Spectrometry (IRMS)

    SciTech Connect

    Harvey, Scott D.; Jarman, Kristin H.; Moran, James J.; Sorensen, Christina M.; Wright, Bob W.

    2011-09-15

    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 between the diesel samples from different sources/locations. The ability to differentiate or correlate diesel samples could be valuable for detecting fuel tax evasion schemes. Two fractionation techniques were used to isolate the n-alkanes from the fuel. Both δ13C and δD values for the n-alkanes were then determined by CSIA in each sample. Plots of δD versus δ13C 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 δ13C, δD, or combined δ13C and δD data on the yielded scores plots that could clearly differentiate the samples, thereby demonstrating the potential of this approach for fingerprinting fuel samples using the δ13C and δD values.

  19. Neutron-Proton Asymmetry Dependence of Spectroscopic Factors in Ar Isotopes

    SciTech Connect

    Lee, Jenny; Tsang, Betty; Shapira, Dan

    2010-01-01

    Spectroscopic factors have been extracted for proton-rich 34Ar and neutron-rich 46Ar using the (p, d) neutron transfer reaction. The experimental results show little reduction of the ground state neutron spectroscopic factor of the proton-rich nucleus 34Ar compared to that of 46Ar. The results suggest that correlations, which generally reduce such spectroscopic factors, do not depend strongly on the neutron-proton asymmetry of the nucleus in this isotopic region as was reported in knockout reactions. The present results are consistent with results from systematic studies of transfer reactions but inconsistent with the trends observed in knockout reaction measurements.

  20. Theoretical calculation of nitrogen isotope equilibrium exchange fractionation factors for various NOy molecules

    NASA Astrophysics Data System (ADS)

    Walters, Wendell W.; Michalski, Greg

    2015-09-01

    The nitrogen stable isotope ratio (15N/14N) of nitrogen oxides (NOx = NO + NO2) and its oxidation products (NOy = NOx + PAN (peroxyacetyl nitrate = C2H3NO5) + HNO3 + NO3 + HONO + N2O5 + ⋯ + particulate nitrates) has been suggested as a tool for partitioning NOx sources; however, the impact of nitrogen (N) equilibrium isotopic fractionation on 15N/14N ratios during the conversion of NOx to NOy must also be considered, but few fractionation factors for these processes have been determined. To address this limitation, computational quantum chemistry calculations of harmonic frequencies, reduced partition function ratios (15β), and N equilibrium isotope exchange fractionation factors (αA/B) were performed for various gaseous and aqueous NOy molecules in the rigid rotor and harmonic oscillator approximations using the B3LYP and EDF2 density functional methods for the mono-substitution of 15N. The calculated harmonic frequencies, 15β, and αA/B are in good agreement with available experimental measurements, suggesting the potential to use computational methods to calculate αA/B values for N isotope exchange processes that are difficult to measure experimentally. Additionally, the effects of solvation (water) on 15β and αA/B were evaluated using the IEF-PCM model, and resulted in lower 15β and αA/B values likely due to the stabilization of the NOy molecules from dispersion interactions with water. Overall, our calculated 15β and αA/B values are accurate in the rigid rotor and harmonic oscillator approximations and will allow for the estimation of αA/B involving various NOy molecules. These calculated αA/B values may help to explain the trends observed in the N stable isotope ratio of NOy molecules in the atmosphere.

  1. Problem of soot aggregates separation and purification for Carbon isotopic composition analyses - burning experiment and real black layers from speleothems examples

    NASA Astrophysics Data System (ADS)

    Hercman, Helena; Zawidzki, Pawel; Majewska, Agata

    2015-04-01

    Burning products are often used as an indicator of fire or prehistoric men activities. When it consists of macroscopically visible black layer it may be studied by different methods. When it is dispersed within sediment it is necessary to apply method for burning product separation. Soot aggregates as a result of incomplete combustion of organic materials are most reliable indication of burning. Size of soot particles is too small to observe by optical microscopy. There are two main advantages of application of transmission electron microscopy (TEM) for investigations of samples formed as a result of organic materials (like wood) combustion. First, it makes possible to investigate not only morphology but also its interior structure. The carbon layers arrangement is characteristic for particles obtained from combustion processes, and it directly confirm that these particles were formed that way. And second, analysis of chemical composition using of EDS spectroscopy in transmission microscope are precise and it spatial resolution is about a few nanometers. Burning chamber for wood burning experiments was constructed. It allows wood burning with controlling of burning temperature, carbon isotopic composition in carbon dioxide of burning atmosphere and carbon dioxide originated during burning. Burning products are collected on the plates with controlling of plates material, temperature and distance from flame. Two types of samples were studied. The first type of samples consisted the products of recent wood burning. The second type of samples consisted of black layers collected from speleothems. Soot aggregates were chemically separated from other burning products collected on plates. Process of chemical separation and purity of soot material were tested by TEM observations. Isotopic carbon composition at each step of soot separation as well as original wood fragments was analysed at the Isotopic Laboratory for Dating and Palaeoenvironment Studies, Polish Academy of

  2. ELECTROMAGNETIC SEPARATION OF ISOTOPES

    DOEpatents

    Barnes, S.W.; Centrell, C.M.

    1960-02-01

    An improved calutron receiver is described having two entrance slots leading to two electrically isolated pockets. A wall of the pocket intended to receive the heavier ions defines one side of the entrance slot to the other pocket and it is so constructed and arranged that the two sides of the wall are substantially equally exposed to the respective ion beams. Thus the per cent rejection of material entering the two entrance slots is the same for each slot.

  3. Upgrade of the resonance ionization laser ion source at ISOLDE on-line isotope separation facility: New lasers and new ion beamsa)

    NASA Astrophysics Data System (ADS)

    Fedosseev, V. N.; Berg, L.-E.; Fedorov, D. V.; Fink, D.; Launila, O. J.; Losito, R.; Marsh, B. A.; Rossel, R. E.; Rothe, S.; Seliverstov, M. D.; Sjödin, A. M.; Wendt, K. D. A.

    2012-02-01

    The resonance ionization laser ion source (RILIS) produces beams for the majority of experiments at the ISOLDE on-line isotope separator. A substantial improvement in RILIS performance has been achieved through a series of upgrade steps: replacement of the copper vapor lasers by a Nd:YAG laser; replacement of the old homemade dye lasers by new commercial dye lasers; installation of a complementary Ti:Sapphire laser system. The combined dye and Ti:Sapphire laser system with harmonics is capable of generating beams at any wavelength in the range of 210-950 nm. In total, isotopes of 31 different elements have been selectively laser-ionized and separated at ISOLDE, including recently developed beams of samarium, praseodymium, polonium, and astatine.

  4. Factors Moderating Children's Adjustment to Parental Separation: Findings from a Community Study in England

    ERIC Educational Resources Information Center

    Cheng, Helen; Dunn, Judy; O'Connor, Thomas G.; Golding, Jean

    2006-01-01

    Research findings show that there is marked variability in children's response to parental separation, but few studies identify the sources of this variation. This prospective longitudinal study examines the factors modifying children's adjustment to parental separation in a community sample of 5,635 families in England. Children's…

  5. The fractionation factors of stable carbon and hydrogen isotope ratios for VOCs

    NASA Astrophysics Data System (ADS)

    Kawashima, H.

    2014-12-01

    Volatile organic compounds (VOCs) are important precursors of ozone and secondary organic aerosols in the atmosphere, some of which are carcinogenic, teratogenic, or mutagenic. VOCs in ambient air originate from many sources, including vehicle exhausts, gasoline evaporation, solvent use, natural gas emissions, and industrial processes, and undergo intricate chemical reactions in the atmosphere. To develop efficient air pollution remediation strategies, it is important to clearly identify the emission sources and elucidate the reaction mechanisms in the atmosphere. Recently, stable carbon isotope ratios (δ13C) of VOCs in some sources and ambient air have been measured by gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS). In this study, we measured δ13C and stable hydrogen isotope ratios (δD) of atmospheric VOCs by using the gas chromatography/thermal conversion/isotope ratio mass spectrometry coupled with a thermal desorption instrument (TD-GC/TC/IRMS). The wider δD differences between sources were found in comparison with the δ13C studies. Therefore, determining δD values of VOCs in ambient air is potentially useful in identifying VOC sources and their reactive behavior in the atmosphere. However, to elucidate the sources and behavior of atmospheric VOCs more accurately, isotopic fractionation during atmospheric reaction must be considered. In this study, we determined isotopic fractionation of the δ13C and δD values for the atmospheric some VOCs under irradiation conditions. As the results, δ13C for target all VOCs and δD for most VOCs were increasing after irradiation. But, the δD values for both benzene and toluene tended to decrease as irradiation time increased. We also estimated the fractionation factors for benzene and toluene, 1.27 and 1.05, respectively, which differed from values determined in previous studies. In summary, we were able to identify an inverse isotope effect for the δD values of benzene and toluene

  6. 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.

  7. 47 CFR 36.3 - Freezing of jurisdictional separations category relationships and/or allocation factors.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... category relationships for the acquiring carrier's post-transfer study area. (e) Any local exchange carrier... relationships and/or allocation factors. 36.3 Section 36.3 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... § 36.3 Freezing of jurisdictional separations category relationships and/or allocation factors....

  8. 47 CFR 36.3 - Freezing of jurisdictional separations category relationships and/or allocation factors.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... category relationships for the acquiring carrier's post-transfer study area. (e) Any local exchange carrier... relationships and/or allocation factors. 36.3 Section 36.3 Telecommunication FEDERAL COMMUNICATIONS COMMISSION... § 36.3 Freezing of jurisdictional separations category relationships and/or allocation factors....

  9. Factors moderating children's adjustment to parental separation: findings from a community study in England.

    PubMed

    Cheng, Helen; Dunn, Judy; O'connor, Thomas G; Golding, Jean

    2006-04-01

    Research findings show that there is marked variability in children's response to parental separation, but few studies identify the sources of this variation. This prospective longitudinal study examines the factors modifying children's adjustment to parental separation in a community sample of 5,635 families in England. Children's behavioral/emotional problems were assessed when children were aged 47 and 81 months; marital quality, maternal depression, socioeconomic circumstances, and demographic variables were assessed prior to the separation from maternal report. Results indicated that 346 mothers separated from their partners in the 3-year period. Preseparation differences were found for measures of family process and parent risk factors, with effect sizes ranging from small to trivial. Parental separation was associated with a significant but modest increase in behavioral/emotional problems, independent of marital quality, maternal depression, socioeconomic circumstances, and demographic variables. Moderation analyses showed that children of cohabiting parents had a greater increase in adjustment problems following parental separation than children of married parents. Further research elucidating the factors that moderate children's adjustment to parental separation is needed to improve our understanding of who may most likely benefit from preventive interventions.

  10. Variability in Isotope Discrimination Factors in Coral Reef Fishes: Implications for Diet and Food Web Reconstruction

    PubMed Central

    Wyatt, Alex S. J.; Waite, Anya M.; Humphries, Stuart

    2010-01-01

    Interpretation of stable isotope ratios of carbon and nitrogen (δ13C and δ15N) is generally based on the assumption that with each trophic level there is a constant enrichment in the heavier isotope, leading to diet-tissue discrimination factors of 3.4‰ for 15N (ΔN) and ∼0.5‰ for 13C (ΔC). Diet-tissue discrimination factors determined from paired tissue and gut samples taken from 152 individuals from 26 fish species at Ningaloo Reef, Western Australia demonstrate a large amount of variability around constant values. While caution is necessary in using gut contents to represent diet due to the potential for high temporal variability, there were significant effects of trophic position and season that may also lead to variability in ΔN under natural conditions. Nitrogen enrichment increased significantly at higher trophic levels (higher tissue δ15N), with significantly higher ΔN in carnivorous species. Changes in diet led to significant changes in ΔN, but not tissue δ15N, between seasons for several species: Acanthurus triostegus, Chromis viridis, Parupeneus signatus and Pomacentrus moluccensis. These results confirm that the use of meta-analysis averages for ΔN is likely to be inappropriate for accurately determining diets and trophic relationships using tissue stable isotope ratios. Where feasible, discrimination factors should be directly quantified for each species and trophic link in question, acknowledging the potential for significant variation away from meta-analysis averages and, perhaps, controlled laboratory diets and conditions. PMID:21060681

  11. Effects of several variable factors on the isotope ratio by HRGC-MS.

    PubMed

    Sawamura, Masayoshi; Satake, Atsushi; Ueno, Takao; Une, Akitoshi; Ukeda, Hiroyuki

    2004-01-01

    In the isotope ratio (Ir) analysis using GC-MS, several variable factors in sampling incidental to any food analysis were investigated for yuzu fruit. The Irs of ten monoterpene hydrocarbons in yuzu essential oils from each of six fruiting positions of three trees were measured. The sign test following t-test of all the Ir values demonstrated that there was no significant difference between both sampling years of 2001 and 2002. There was also no significant variation in the Ir values among the three trees and six fruiting positions in the individual two years.

  12. Theoretical calculation of oxygen equilibrium isotope fractionation factors involving various NOy molecules, radOH, and H2O and its implications for isotope variations in atmospheric nitrate

    NASA Astrophysics Data System (ADS)

    Walters, Wendell W.; Michalski, Greg

    2016-10-01

    The oxygen stable isotope composition (δ18O) of nitrogen oxides [NOx = nitric oxide (NO) + nitrogen dioxide (NO2)] and their oxidation products (NOy = NOx + nitric acid (HNO3) + particulate nitrate (p-NO3-) + nitrate radical (NO3) + dinitrogen pentoxide (N2O5) + nitrous acid (HONO) + …) have been shown to be a useful tool for inferring the proportion of NOx that is oxidized by ozone (O3). However, isotopic fractionation processes may have an influence on δ18O of various NOy molecules and other atmospheric O-bearing molecules pertinent to NOx oxidation chemistry. Here we have evaluated the impacts of O isotopic exchange involving NOy molecules, the hydroxyl radical (radOH), and water (H2O) using reduced partition function ratios (xβ) calculated by hybrid density functional theory. Assuming atmospheric isotopic equilibrium is achieved between NO and NO2 during the daytime, and NO2, NO3, and N2O5 during the nighttime, δ18O-δ15N compositions were predicted for the major atmospheric nitrate formation pathways using our calculated exchange fractionation factors and isotopic mass-balance. Our equilibrium model predicts that various atmospheric nitrate formation pathways, including NO2 + radOH → HNO3, N2O5 + H2O + surface → 2HNO3, and NO3 + R → HNO3 + Rrad will yield distinctive δ18O-δ15N compositions. Our calculated δ18O-δ15N compositions match well with previous atmospheric nitrate measurements, and will potentially help better understand the role oxidation chemistry plays on the N and O isotopic composition of atmospheric nitrate.

  13. 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.

  14. Effective Boson Number- A New Approach for Predicting Separation Energies with the IBM1, Applied to Zr, Kr, Sr isotopes near A = 100

    NASA Astrophysics Data System (ADS)

    Paul, Nancy; van Isacker, Pieter; García Ramos, José Enrique; Aprahamian, Ani

    2011-10-01

    This work uses effective boson numbers in the Interacting Boson Model (IBM1) to predict two neutron separation energies for neutron-rich zirconium, strontium, and krypton isotopes., We determine the functional forms of binding energy and excitation energies as a function of boson number for a given choice of IBM parameters that give a good overall description of the experimental spectra of the isotopic chain. The energy of the first excited 2+ level is then used to extract an effective boson number for a given nucleus, that is in turn used to calculate the separation energies. This method accounts for complex interactions among valence nucleons around magic and semi- magic nuclei and successfully predicts the phase transitional signature in separation energies around A=100 for 92-108Zr, 90-104Sr, and 86-96Kr Supported by the NSF under contract PHY0758100, the Joint Institute for Nuclear Astrophysics grant PHY0822648, University of Notre Dame Nanovic Institute, Glynn Family Honors Program, Center for Undergraduate Scholarly Engagement.

  15. A fully automated system with online sample loading, isotope dimethyl labeling and multidimensional separation for high-throughput quantitative proteome analysis.

    PubMed

    Wang, Fangjun; Chen, Rui; Zhu, Jun; Sun, Deguang; Song, Chunxia; Wu, Yifeng; Ye, Mingliang; Wang, Liming; Zou, Hanfa

    2010-04-01

    Multidimensional separation is often applied for large-scale qualitative and quantitative proteome analysis. A fully automated system with integration of a reversed phase-strong cation exchange (RP-SCX) biphasic trap column into vented sample injection system was developed to realize online sample loading, isotope dimethyl labeling and online multidimensional separation of the proteome samples. Comparing to conventionally manual isotope labeling and off-line fractionation technologies, this system is fully automated and time-saving, which is benefit for improving the quantification reproducibility and accuracy. As phosphate SCX monolith was integrated into the biphasic trap column, high sample injection flow rate and high-resolution stepwise fractionation could be easily achieved. Approximately 1000 proteins could be quantified in approximately 30 h proteome analysis, and the proteome coverage of quantitative analysis can be further greatly improved by prolong the multidimensional separation time. This system was applied to analyze the different protein expression level of HCC and normal human liver tissues. After three times replicated analysis, finally 94 up-regulated and 249 down-regulated (HCC/Normal) proteins were successfully obtained. These significantly regulated proteins are widely validated by both gene and proteins expression studies previously. Such as some enzymes involved in urea cycle, methylation cycle and fatty acids catabolism in liver were all observed down-regulated.

  16. Factors Controlling the Stable Nitrogen Isotopic Composition (δ15N) of Lipids in Marine Animals

    PubMed Central

    Svensson, Elisabeth; Schouten, Stefan; Hopmans, Ellen C.; Middelburg, Jack J.; Sinninghe Damsté, Jaap S.

    2016-01-01

    Lipid extraction of biomass prior to stable isotope analysis is known to cause variable changes in the stable nitrogen isotopic composition (δ15N) of residual biomass. However, the underlying factors causing these changes are not yet clear. Here we address this issue by comparing the δ15N of bulk and residual biomass of several marine animal tissues (fish, crab, cockle, oyster, and polychaete), as well as the δ15N of the extracted lipids. As observed previously, lipid extraction led to a variable offset in δ15N of biomass (differences ranging from -2.3 to +1.8 ‰). Importantly, the total lipid extract (TLE) was highly depleted in 15N compared to bulk biomass, and also highly variable (differences ranging from -14 to +0.7 ‰). The TLE consisted mainly of phosphatidylcholines, a group of lipids with one nitrogen atom in the headgroup. To elucidate the cause for the 15N-depletion in the TLE, the δ15N of amino acids was determined, including serine because it is one of the main sources of nitrogen to N-containing lipids. Serine δ15N values differed by -7 to +2 ‰ from bulk biomass δ15N, and correlated well with the 15N depletion in TLEs. On average, serine was less depleted (-3‰) than the TLE (-7 ‰), possibly due to fractionation during biosynthesis of N-containing headgroups, or that other nitrogen-containing compounds, such as urea and choline, or recycled nitrogen contribute to the nitrogen isotopic composition of the TLE. The depletion in 15N of the TLE relative to biomass increased with the trophic level of the organisms. PMID:26731720

  17. Factors controlling precision and accuracy in isotope-ratio-monitoring mass spectrometry

    NASA Technical Reports Server (NTRS)

    Merritt, D. A.; Hayes, J. M.

    1994-01-01

    The performance of systems in which picomole quantities of sample are mixed with a carrier gas and passed through an isotope-ratio mass spectrometer system was examined experimentally and theoretically. Two different mass spectrometers were used, both having electron-impact ion sources and Faraday cup collector systems. One had an accelerating potential of 10kV and accepted 0.2 mL of He/min, producing, under those conditions, a maximum efficiency of 1 CO2 molecular ion collected per 700 molecules introduced. Comparable figures for the second instrument were 3 kV, 0.5 mL of He/min, and 14000 molecules/ion. Signal pathways were adjusted so that response times were <200 ms. Sample-related ion currents appeared as peaks with widths of 3-30 s. Isotope ratios were determined by comparison to signals produced by standard gases. In spite of rapid variations in signals, observed levels of performance were within a factor of 2 of shot-noise limits. For the 10-kV instrument, sample requirements for standard deviations of 0.1 and 0.5% were 45 and 1.7 pmol, respectively. Comparable requirements for the 3-kV instrument were 900 and 36 pmol. Drifts in instrumental characteristics were adequately neutralized when standards were observed at 20-min intervals. For the 10-kV instrument, computed isotopic compositions were independent of sample size and signal strength over the ranges examined. Nonlinearities of <0.04%/V were observed for the 3-kV system. Procedures for observation and subtraction of background ion currents were examined experimentally and theoretically. For sample/ background ratios varying from >10 to 0.3, precision is expected and observed to decrease approximately 2-fold and to depend only weakly on the precision with which background ion currents have been measured.

  18. Factors Controlling the Stable Nitrogen Isotopic Composition (δ15N) of Lipids in Marine Animals.

    PubMed

    Svensson, Elisabeth; Schouten, Stefan; Hopmans, Ellen C; Middelburg, Jack J; Sinninghe Damsté, Jaap S

    2016-01-01

    Lipid extraction of biomass prior to stable isotope analysis is known to cause variable changes in the stable nitrogen isotopic composition (δ15N) of residual biomass. However, the underlying factors causing these changes are not yet clear. Here we address this issue by comparing the δ15N of bulk and residual biomass of several marine animal tissues (fish, crab, cockle, oyster, and polychaete), as well as the δ15N of the extracted lipids. As observed previously, lipid extraction led to a variable offset in δ15N of biomass (differences ranging from -2.3 to +1.8 ‰). Importantly, the total lipid extract (TLE) was highly depleted in 15N compared to bulk biomass, and also highly variable (differences ranging from -14 to +0.7 ‰). The TLE consisted mainly of phosphatidylcholines, a group of lipids with one nitrogen atom in the headgroup. To elucidate the cause for the 15N-depletion in the TLE, the δ15N of amino acids was determined, including serine because it is one of the main sources of nitrogen to N-containing lipids. Serine δ15N values differed by -7 to +2 ‰ from bulk biomass δ15N, and correlated well with the 15N depletion in TLEs. On average, serine was less depleted (-3‰) than the TLE (-7 ‰), possibly due to fractionation during biosynthesis of N-containing headgroups, or that other nitrogen-containing compounds, such as urea and choline, or recycled nitrogen contribute to the nitrogen isotopic composition of the TLE. The depletion in 15N of the TLE relative to biomass increased with the trophic level of the organisms.

  19. 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

    NASA Astrophysics Data System (ADS)

    Makarov, G. N.; Petin, A. N.

    2016-03-01

    We report the results of studies on the isotope-selective infrared multiphoton dissociation (IR MFD) of SF6 and CF3I 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 SF6 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 a 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.

  20. Factor Study for the Separator Plate of Mcfc Having Uniform Stiffness at Elevated Temperature

    NASA Astrophysics Data System (ADS)

    Lee, Sang-Wook; Kim, Jung-Hyun; Jun, Joong-Hwan

    A molten carbonate fuel cell (MCFC) is composed of several stacks of unit cells. A unit cell is composed of two electrodes and a matrix that is inserted between separator plates. Separator plates should properly contact the electrodes to reduce the electricity loss arising from contact resistance. To this end, a pressure of about 2 kgf/cm2 is usually applied on the top of the stack, which results in the separator plates being somewhat compacted. Furthermore, the stiffness of the separator plates becomes degraded at elevated temperatures due to softening of the plate materials. Therefore, a nonuniform temperature distribution across the separator plates induced by exothermic reactions of the oxidant and reactant gases leads to a non-uniform plate stiffness. This study has firstly evaluated the change in separator plate stiffness as temperature changes by applying pressure to the plates. Secondly, using the Taguchi method, several design factors that affect stiffness have been investigated to determine which has the most influence. Based on these results, a new design for the separators, which allows for uniform stiffness at elevated temperatures, has been proposed.

  1. Nonnegative matrix factorization: a blind spectra separation method for in vivo fluorescent optical imaging.

    PubMed

    Montcuquet, Anne-Sophie; Hervé, Lionel; Navarro, Fabrice; Dinten, Jean-Marc; Mars, Jérôme I

    2010-01-01

    Fluorescence imaging in diffusive media is an emerging imaging modality for medical applications that uses injected fluorescent markers that bind to specific targets, e.g., carcinoma. The region of interest is illuminated with near-IR light and the emitted back fluorescence is analyzed to localize the fluorescence sources. To investigate a thick medium, as the fluorescence signal decreases with the light travel distance, any disturbing signal, such as biological tissues intrinsic fluorescence (called autofluorescence) is a limiting factor. Several specific markers may also be simultaneously injected to bind to different molecules, and one may want to isolate each specific fluorescent signal from the others. To remove the unwanted fluorescence contributions or separate different specific markers, a spectroscopic approach is explored. The nonnegative matrix factorization (NMF) is the blind positive source separation method we chose. We run an original regularized NMF algorithm we developed on experimental data, and successfully obtain separated in vivo fluorescence spectra.

  2. A First Look at Graphite Grains from Orgueil: Morphology, Carbon, Nitrogen and Neon Isotopic Compositions of Individual, Chemically Separated Grains

    NASA Technical Reports Server (NTRS)

    Pravdivtseva, O.; Zinner, E.; Meshik, A. P.; Hohenberg, C. M.; Walker, R. W.

    2004-01-01

    Presolar graphite in Murchison has been extensively studied. It is characterized by a unique Ne isotopic composition, known as the Ne-E(L) component. According to studies by Huss and Lewis, the concentration of Ne-E(L) in Orgueil is about one order of magnitude higher than in Murchison, when normalized to the matrix. This could be due to a higher presolar graphite abundance in Orgueil, or due to a higher Ne-E concentrations per grain. The Ne isotopic compositions in individual presolar graphite grains from Murchison have been measured before. It was shown, that a third of the grains have detectable excesses in 22Ne, characteristic of the Ne-E(L) component. One grain in a hundred had a Ne-22 concentration two orders of magnitude higher than blank.

  3. Movement Precision and Amplitude as Separate Factors in the Control of Movement.

    ERIC Educational Resources Information Center

    Kerr, Robert

    The purpose of this study was to assess Welford's dual controlling factor interpretation of Fitts' Law--describing movement time as being a linear function of movement distance (or amplitude) and the required precision of the movement (or target width). Welford's amplification of the theory postulates that two separate processes ought to be…

  4. Large volume injection in ion chromatography Separation of rubidium and strontium for on-line inductively coupled plasma mass spectrometry determination of strontium isotope ratios.

    PubMed

    García-Ruiz, Silvia; Moldovan, Mariella; García Alonso, J Ignacio

    2007-05-18

    Large volume injection, up to 5 mL, was evaluated and optimised for the on-line ion chromatographic separation of Rb and Sr before ICP-MS measurement of Sr isotope ratios. Flat-topped chromatographic peaks, ideally suited for multicollector ICP-MS isotope ratio measurements, could be obtained when the composition of the mobile phase (nitric acid and 18-crown-6 ether) was identical to the matrix of the sample. Under those conditions rubidium eluted at the dead volume of the column while strontium produced a flat-topped transient signal with several minutes of stable plateau. On-line data acquisition during several minutes at the plateau of Sr signal allowed high precision Sr isotope ratio measurement. The developed procedure was evaluated for Sr isotope ratio measurements on different types of samples, including cider, apples, apple leaves, and soil extracts, in the frame of a long-term project aiming at origin authentication using strontium isotope ratio measurements. It was observed that sample matrix caused broadening of the strontium chromatographic peak and loss of flat-topped peak profile. Under those circumstances the addition of the complexing crown-ether 18-crown-6 both to samples and chromatographic eluent provided two distinct advantages. First, a drastic increase in the retention of strontium was observed which could be modulated by increasing the concentration of nitric acid in the eluent up to 900 mM. This increase in the eluent HNO(3) concentration allowed the application of the method to acid soil digests and other high acidity samples. Second, the matrix of the sample did not affect any more the chromatographic peak profile and similar chromatographic separations could be obtained for samples and standards maintaining the flat-topped Sr peak profile. Sample preparation consisted of a simple 1:10 dilution of the cider or pre-treated solid samples by adding HNO(3) (900 mM) and 18-crown-6 ether (5mM) to obtain similar composition in the sample solution

  5. Solid-state Marx based two-switch voltage modulator for the On-Line Isotope Mass Separator accelerator at the European Organization for Nuclear Research

    SciTech Connect

    Redondo, L. M.; Canacsinh, H.; Ferrao, N.; Mendes, C.; Silva, J. Fernando; Soares, R.; Schipper, J.; Fowler, A.

    2010-07-15

    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.

  6. Improving stable carbon and oxygen isotope geochemical measurements in dolomite: reference material and acid fractionation factor

    NASA Astrophysics Data System (ADS)

    Vandeginste, V.; John, C. M.; Jourdan, A.; Davis, S.

    2010-12-01

    The analysis of stable carbon and oxygen isotope composition is one of the most commonly used techniques in stratigraphic and diagenetic research of carbonate rocks. The wide-spread use and easy access of this long-established method has the side effect that little attention is paid to fundamental calibrations. Dolomite is often measured against a calcite standard (NBS19), and the acid fractionation factor used to calibrate is based on the one for calcite. To date, no reference material exists for dolomite. In this study, which is part of dolomite research in the Qatar Carbonates and Carbon Storage Research Centre project, we focus on two main goals. First, we characterize a current standard of dolomite used for major and minor elemental geochemistry, and assess its suitability as a new dolomite standard for δ18O and δ13C. Second, we attempt to better constrain the acid fractionation factor for dolomite and assess the influence of different dolomite types on this fractionation factor. As only two third of the total oxygen in the carbonate is released in the form of CO2 during acid reaction, a fractionation between the reacting carbonate and the resulting gas will occur. A recent study by Kim et al. (2007) improved on the acid fractionation factors for calcite and aragonite. Often, the acid fractionation factor for dolomite is used to calculate δ18O and δ13C from the values obtained by calibration with the calcite standard. Only two studies (from the 1980’s) have attempted to constrain the acid fractionation factor for dolomite, of which only Rosenbaum and Sheppard (1986) did experiments not only at 25°C, but also at 50 and 100°C. The dataset of the latter authors is, however, very limited and contains only two dolomite samples. We aim at improving the constraints on the acid fractionation factor of dolomite by reacting a wide range of different types of dolomite at a wide range of acid temperature, and compare this to the absolute isotopic composition of

  7. 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.

  8. 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

  9. Spatial separation of groundwater flow paths from a multi-flow system by a simple mixing model using stable isotopes of oxygen and hydrogen as natural tracers

    NASA Astrophysics Data System (ADS)

    Nakaya, Shinji; Uesugi, Kenji; Motodate, Yusuke; Ohmiya, Isao; Komiya, Hiroyuki; Masuda, Harue; Kusakabe, Minoru

    2007-09-01

    Stable isotopes of oxygen and hydrogen have the potential to serve as tracers for both source and flow paths in a groundwater system. The ratios of stable isotopes of oxygen (δ18O) and hydrogen (δD) can be used as natural tracer parameters to separate multiflow groundwater paths by applying a simple inversion analysis method to determine the differences between observed and calculated δ18O and δD data in a simple mixing model. The model presented here assumes that the distribution of natural tracers in the steady state is governed by simple mixing between flow paths with a normal distribution of flow rate. When the inversion analysis and simple mixing model were applied to the multiflow system of the Matsumoto Basin, which is surrounded by Japanese alpine ranges, the end-members of the relationship between observed δ18O and δD could be separated spatially into specific groundwater flow paths in the multiflow system of shallow and deep groundwater flow paths.

  10. Growth variability and stable isotope composition of two larval carangid fishes in the East Australian Current: The role of upwelling in the separation zone

    NASA Astrophysics Data System (ADS)

    Syahailatua, Augy; Taylor, Matthew D.; Suthers, Iain M.

    2011-03-01

    The larvae of two carangid fishes, silver trevally ( Pseudocaranx dentex) and yellowtail scad ( Trachurus novaezelandiae), were compared among coastal water masses and the East Australian Current (EAC). Samples followed a north to south gradient including a southern region of upwelling, generated as the EAC separated from the coast. Mean larval carangid densities were greater in the mixed layer (10-30 m) than the surface, but there was no difference between inshore and offshore stations or along latitudinal gradients. Overall, P. dentex recent larval growth over two days pre-capture was faster than T. novaezelandiae, and faster at inshore, coastal stations than in the EAC. Integrated larval growth rate (mm d -1) was usually faster at inshore stations for both species. T. novaezelandiae were enriched in both nitrogen (δ 15N) and carbon (δ 13C) stable isotopes relative to P. dentex. Larvae of both species captured within the upwelling region were enriched in δ 15N and depleted in δ 13C relative to other sites. Recent larval growth had a significant positive relationship with fluorescence (as a proxy of chlorophyll a biomass), and integrated larval growth rate had a significant positive relationship with fluorescence and larval isotope (δ 15N) composition. Recent and integrated growth of larval T. novaezelandiae and P. dentex was enhanced by EAC separation and upwelling, and also in coastal water; stimulated by food availability, and potentially through exploitation of a different trophic niche.

  11. First calibration measurements of an FTIR absorption spectroscopy system for liquid hydrogen isotopologues for the isotope separation system of fusion power plants

    SciTech Connect

    Groessle, R.; Beck, A.; Bornschein, B.; Fischer, S.; Kraus, A.; Mirz, S.; Rupp, S.

    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 at 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)

  12. Astrophysical S factors for fusion reactions involving C, O, Ne, and Mg isotopes

    SciTech Connect

    Beard, M.; Afanasjev, A.V.; Chamon, L.C.; Gasques, L.R.; Wiescher, M.; Yakovlev, D.G.

    2010-09-15

    Using the Sao Paulo potential and the barrier penetration formalism we have calculated the astrophysical factor S(E) for 946 fusion reactions involving stable and neutron-rich isotopes of C, O, Ne, and Mg for center-of-mass energies E varying from 2 to {approx}18-30 MeV (covering the range below and above the Coulomb barrier). We have parameterized the energy dependence, S(E), by an accurate universal 9-parameter analytic expression and present tables of fit parameters for all the reactions. We also discuss the reduced 3-parameter version of our fit which is highly accurate at energies below the Coulomb barrier, and outline the procedure for calculating the reaction rates. The results can be easily converted to thermonuclear or pycnonuclear reaction rates to simulate various nuclear burning phenomena, in particular, stellar burning at high temperatures and nucleosynthesis in high density environments.

  13. Precise determination of atomic g-factor ratios from a dual isotope magneto-optical trap

    SciTech Connect

    Chan, I.; Barrett, B.; Kumarakrishnan, A.

    2011-09-15

    We demonstrate a technique, for carrying out precise measurements of atomic g-factor ratios, which relies on measurements of Larmor oscillations from coherences between magnetic sublevels in the ground states of {sup 85}Rb and {sup 87}Rb atoms confined in a dual isotope magneto-optical trap. We show that a measurement of g{sub F}{sup (87)}/g{sub F}{sup (85)} with a resolution of 0.69 parts per 10{sup 6} is possible by recording the ratio of Larmor frequencies in the presence of a constant magnetic field. This represents the most precise single measurement of g{sub F}{sup (87)}/g{sub F}{sup (85)} without correcting for systematic effects.

  14. Heterodynes dominate precipitation isotopes in the East Asian monsoon region, reflecting interaction of multiple climate factors

    NASA Astrophysics Data System (ADS)

    Thomas, Elizabeth K.; Clemens, Steven C.; Sun, Youbin; Prell, Warren L.; Huang, Yongsong; Gao, Li; Loomis, Shannon; Chen, Guangshan; Liu, Zhengyu

    2016-12-01

    For the past decade, East Asian monsoon history has been interpreted in the context of an exceptionally well-dated, high-resolution composite record of speleothem oxygen isotopes (δ18Ocave) from the Yangtze River Valley. This record is characterized by a unique spectral response, with variance concentrated predominantly within the precession band and an enigmatic lack of variance at the eccentricity and obliquity bands. Here we examine the spectral characteristics of all existing >250-kyr-long terrestrial water isotope records in Asia, including a new water isotope record using leaf wax hydrogen isotope ratios from the Chinese Loess Plateau. There exist profound differences in spectral characteristics among all orbital-scale Asian water isotope records. We demonstrate that these differences result from latitudinal gradients in the influence of the winter and summer monsoons, both of which impact climate and water isotopes throughout East Asia. Water isotope records therefore do not reflect precipitation during a single season or from a single circulation system. Rather, water isotope records in East Asia reflect the complex interplay of oceanic and continental moisture sources, operating at multiple Earth-orbital periods. These non-linear interactions are reflected in water isotope spectra by the presence of heterodynes. Although complex, we submit that water isotope records, when paired with rapidly developing isotope-enabled model simulations, will have the potential to elucidate mechanisms causing seasonal precipitation variability and moisture source variability in East Asia.

  15. X-ray Intermolecular Structure Factor (XISF): separation of intra- and intermolecular interactions from total X-ray scattering data

    SciTech Connect

    Mou, Q.; Benmore, C. J.; Yarger, J. L.

    2015-06-01

    XISF is a MATLAB program developed to separate intermolecular structure factors from total X-ray scattering structure factors for molecular liquids and amorphous solids. The program is built on a trust-region-reflective optimization routine with the r.m.s. deviations of atoms physically constrained. XISF has been optimized for performance and can separate intermolecular structure factors of complex molecules.

  16. Clustering Algorithm for Unsupervised Monaural Musical Sound Separation Based on Non-negative Matrix Factorization

    NASA Astrophysics Data System (ADS)

    Park, Sang Ha; Lee, Seokjin; Sung, Koeng-Mo

    Non-negative matrix factorization (NMF) is widely used for monaural musical sound source separation because of its efficiency and good performance. However, an additional clustering process is required because the musical sound mixture is separated into more signals than the number of musical tracks during NMF separation. In the conventional method, manual clustering or training-based clustering is performed with an additional learning process. Recently, a clustering algorithm based on the mel-frequency cepstrum coefficient (MFCC) was proposed for unsupervised clustering. However, MFCC clustering supplies limited information for clustering. In this paper, we propose various timbre features for unsupervised clustering and a clustering algorithm with these features. Simulation experiments are carried out using various musical sound mixtures. The results indicate that the proposed method improves clustering performance, as compared to conventional MFCC-based clustering.

  17. Form factors and complete spectrum of XXX antiperiodic higher spin chains by quantum separation of variables

    SciTech Connect

    Niccoli, G.

    2013-05-15

    The antiperiodic transfer matrices associated to higher spin representations of the rational 6-vertex Yang-Baxter algebra are analyzed by generalizing the approach introduced recently in the framework of Sklyanin's quantum separation of variables (SOV) for cyclic representations, spin-1/2 highest weight representations, and also for spin-1/2 representations of the 6-vertex reflection algebra. Such SOV approach allow us to derive exactly results which represent complicate tasks for more traditional methods based on Bethe ansatz and Baxter Q-operator. In particular, we both prove the completeness of the SOV characterization of the transfer matrix spectrum and its simplicity. Then, the derived characterization of local operators by Sklyanin's quantum separate variables and the expression of the scalar products of separate states by determinant formulae allow us to compute the form factors of the local spin operators by one determinant formulae similar to those of the scalar products.

  18. The Western Ghat as the water tower of the South Indian Rivers : a stable isotope investigation on the origin of water and factors affecting the water cycle.

    NASA Astrophysics Data System (ADS)

    Lambs, Luc; Tripti, Muguli; Balakrishna, Keshava

    2014-05-01

    The long stretch (1600 km) of Ghats on the western side (Western Ghats) of Peninsular India separates relatively wetter west coast from drier eastern coast. The western and eastern sides of the Ghats are having distinct isotopic signatures indicating unequal distribution of the moisture sources. South India is characterized by having moisture source for southwest monsoon from Arabian Sea and northeast monsoon from Bay of Bengal. The wetter side of Peninsular region is covered by combination of evergreen tropical forest and grass lands, termed as Shola Forests which support higher vapor recycling process. Very few isotopic studies have been undertaken in these areas, except few places, mainly along the coast lines. This study presents the stable isotope results on rivers and groundwater of the Western Ghats covering Agumbe (Karnataka) to Ooty (Tamil Nadu) and its west coast river basins as observed for the three year period. The stable isotope results on the surface, subsurface and deep water pools show that the mean d18O value range from -4 o to -2 o on the west slope, and from -5 o to -4 o on the east slope, with quite no altitude or amount effect up to 2000 m asl. The more depleted values are found only in higher elevation, like the Doddabeta in the Nilgiri (2637m), with d18O close to -9 o which is exceptional for a tropical area. The hills on the west slope of the Western Ghats as well as in the mountainous Shola forest exhibit strong water vapor recycling as evidenced by high d-excess values. On the contrary on the eastern slope, the drier condition and the numerous impoundments and river damming support strong evaporation process. Thus, the study identifies the profound effect of tropical vegetation and anthropogenic factors on the recharge functioning of river and groundwater pools in Southern India.

  19. Chapter 13 Petrogenesis of the Campanian Ignimbrite: implications for crystal-melt separation and open-system processes from major and trace elements and Th isotopic data

    USGS Publications Warehouse

    Bohrson, W.A.; Spera, F.J.; Fowler, S.J.; Belkin, H.E.; de Vivo, B.; Rolandi, G.

    2006-01-01

    The Campanian Ignimbrite is a large-volume trachytic to phonolitic ignimbrite that was deposited at ???39.3 ka and represents one of a number of highly explosive volcanic events that have occurred in the region near Naples, Italy. Thermodynamic modeling using the MELTS algorithm reveals that major element variations are dominated by crystal-liquid separation at 0.15 GPa. Initial dissolved H2O content in the parental melt is ???3 wt.% and the magmatic system fugacity of oxygen was buffered along QFM+1. Significantly, MELTS results also indicate that the liquid line of descent is marked by a large change in the proportion of melt (from 0.46 to 0.09) at ???884??C, which leads to a discontinuity in melt composition (i.e., a compositional gap) and different thermodynamic and transport properties of melt and magma across the gap. Crystallization of alkali feldspar and plagioclase dominates the phase assemblage at this pseudo-invariant point temperature of ???884??C. Evaluation of the variations in the trace elements Zr, Nb, Th, U, Rb, Sm, and Sr using a mass balance equation that accounts for changing bulk mineral-melt partition coefficients as crystallization occurs indicates that crystal-liquid separation and open-system processes were important. Th isotope data yield an apparent isochron that is ???20 kyr younger than the age of the deposit, and age-corrected Th isotope data indicate that the magma body was an open system at the time of eruption. Because open-system behavior can profoundly change isotopic and elemental characteristics of a magma body, these Th results illustrate that it is critical to understand the contribution that open-system processes make to magmatic systems prior to assigning relevance to age or timescale information derived from such systems. Fluid-magma interaction has been proposed as a mechanism to change isotopic and elemental characteristics of magma bodies, but an evaluation of the mass and thermal constraints on such a process suggests

  20. Separating Autotrophic and Heterotrophic Contributions to Soil Respiration in Maize-Based Agroecosystems Using Stable Carbon Isotope Ratio Mass Spectrometry.

    NASA Astrophysics Data System (ADS)

    Amos, B.; Walters, D. T.; Madhavan, S.; Arkebauer, T. J.; Scoby, D. L.

    2005-12-01

    Any effort to establish a carbon budget for a growing crop by means of a thorough accounting of all C sources and sinks will require the ability to discriminate between autotrophic and heterotrophic contributions to soil surface CO2 flux. Autotrophic soil respiration (Ra) is defined as combined root respiration and the respiration of soil microorganisms residing in the rhizosphere and using root-derived carbohydrates as an energy source, while heterotrophic respiration (Rh) is defined as the respiration of soil microorganisms and macroorganisms not directly under the influence of the live root system and using SOM as an energy source. We partition soil surface CO2 flux into its autotrophic and heterotrophic components by combining root exclusion with stable carbon isotope techniques in production scale (~65 ha) maize-based agroecosystems. After flux measurements, small chambers are placed on collars in both root excluded shields and in non-root excluded soil, ambient headspace CO2 is removed using a soda lime trap, and soil-respired C is allowed to collect in the chambers. Soil respiration samples are then collected in 12mL evacuated exetainers and analyzed for δ13C by means of a Finnigan Delta-S isotope ratio mass spectrometer interfaced with a Thermo Finnigan GasBench II and a cryogenic trap to increase CO2 concentration. These δ13C measurements were made throughout the 2005 growing season in maize fields representing three agroecosystems: irrigated continuous maize, irrigated maize-soybean rotation, and rainfed maize soybean rotation. Estimates of autotrophic and heterotrophic soil respiration along with other results of this study will be presented.

  1. 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

    SciTech Connect

    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 a 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)

  2. Purification of human immunoglobulin G autoantibodies to tumor necrosis factor using affinity chromatography and magnetic separation.

    PubMed

    Sennikov, S V; Golikova, E A; Kireev, F D; Lopatnikova, J A

    2013-04-30

    Autoantibodies to cytokines are important biological effector molecules that can regulate cytokine activities. The aim of the study was to develop a protocol to purify autoantibodies to tumor necrosis factor from human serum, for use as a calibration material to determine the absolute content of autoantibodies to tumor necrosis factor by enzyme-linked immunosorbent assay. The proposed protocol includes a set of affinity chromatography methods, namely, Bio-Gel P6DG sorbent to remove albumin from serum, Protein G Sepharose 4 Fast Flow to obtain a total immunoglobulin G fraction of serum immunoglobulins, and Affi-Gel 15 to obtain specifically antibodies to tumor necrosis factor. The addition of a magnetic separation procedure to the protocol eliminated contaminant tumor necrosis factor from the fraction of autoantibodies to tumor necrosis factor. The protocol generated a pure fraction of autoantibodies to tumor necrosis factor, and enabled us to determine the absolute concentrations of different subclasses of immunoglobulin G autoantibodies to tumor necrosis factor in apparently healthy donors.

  3. Spatial distribution and controlling factors of stable isotopes in meteoric waters on the Tibetan Plateau: Implications for paleoelevation reconstruction

    NASA Astrophysics Data System (ADS)

    Li, Lin; Garzione, Carmala N.

    2017-02-01

    Debates persist about the interpretations of stable isotope based proxies for the surface uplift of the central-northern Tibetan Plateau. These disputes arise from the uncertain relationship between elevation and the δ18 O values of meteoric waters, based on modern patterns of isotopes in precipitation and surface waters. We present a large river water data set (1,340 samples) covering most parts of the Tibetan Plateau to characterize the spatial variability and controlling factors of their isotopic compositions. Compared with the amount-weighted mean annual oxygen isotopic values of precipitation, we conclude that river water is a good substitute for isotopic studies of precipitation in the high flat (e.g., elevation >3,300 m) interior of the Tibetan Plateau in the mean annual timescale. We construct, for the first time based on field data, contour maps of isotopic variations of meteoric waters (δ18 O, δD and d-excess) on the Tibetan Plateau. In the marginal mountainous regions of the Plateau, especially the southern through eastern margins, the δ18 O and δD values of river waters decrease with increasing mean catchment elevation, which can be modeled as a Rayleigh distillation process. However, in the interior of the Plateau, northward increasing trends in δ18 O and δD values are pronounced and present robust linear relations; d-excess values are lower than the marginal regions and exhibit distinct contrasts between the eastern (8 ‰- 12 ‰) and western (<8‰) Plateau. We suggest that these isotopic features of river waters in the interior of the Tibetan Plateau result from the combined effects of: 1) mixing of different moisture sources transported by the South Asian monsoon and Westerly winds; 2) contribution of moisture from recycled surface water; and 3) sub-cloud evaporation. We further provide a sub-cloud evaporation modified Rayleigh distillation and mixing model to simulate the isotopic variations in the western Plateau. Results of this work

  4. Nonnegative matrix factorization: a blind sources separation method to extract content of fluorophores mixture media

    NASA Astrophysics Data System (ADS)

    Zhou, Kenneth J.; Chen, Jun

    2014-03-01

    The fluorophores of malignant human breast cells change their compositions that may be exposed in the fluorescence spectroscopy and blind source separation method. The content of the fluorophores mixture media such as tryptophan, collagen, elastin, NADH, and flavin were varied according to the cancer development. The native fluorescence spectra of these key fluorophores mixture media excited by the selective excitation wavelengths of 300 nm and 340 nm were analyzed using a blind source separation method: Nonnegative Matrix Factorization (NMF). The results show that the contribution from tryptophan, NADH and flavin to the fluorescence spectra of the mixture media is proportional to the content of each fluorophore. These data present a possibility that native fluorescence spectra decomposed by NMF can be used as potential native biomarkers for cancer detection evaluation of the cancer.

  5. Ca isotope stratigraphy across the Cenomanian-Turonian OAE 2: Links between volcanism, seawater geochemistry, and the carbonate fractionation factor

    NASA Astrophysics Data System (ADS)

    Du Vivier, Alice D. C.; Jacobson, Andrew D.; Lehn, Gregory O.; Selby, David; Hurtgen, Matthew T.; Sageman, Bradley B.

    2015-04-01

    The Ca isotope composition of marine carbonate rocks offers potential to reconstruct drivers of environmental change in the geologic past. This study reports new, high-precision Ca isotope records (δ44/40Ca; 2σSD = ± 0.04 ‰) for three sections spanning a major perturbation to the Cretaceous ocean-climate system known as Ocean Anoxic Event 2 (OAE 2): central Colorado, USA (Portland #1 core), southeastern France (Pont d'Issole), and Hokkaido, Japan (Oyubari, Yezo Group). In addition, we generated new data for selected samples from Eastbourne, England (English Chalk), where a previous Ca isotope study was completed using different methodology (Blättler et al., 2011). Strata of the Yezo Group contain little carbonate (∼1 wt.% on average) and accordingly did not yield a clear δ44/40Ca signal. The Portland core and the Pont d'Issole section display comparable δ44/40Ca values, which increase by ∼ 0.10- 0.15 ‰ at the onset of OAE 2 and then decrease to near-initial values across the event. The Eastbourne δ44/40Ca values are higher than previously reported. They are also higher than the δ44/40Ca values for the Portland core and the Pont d'Issole section but define a similar pattern. According to a numerical model of the marine Ca cycle, elevated hydrothermal inputs have little impact on seawater δ44/40Ca values. Elevated riverine (chemical weathering) inputs produce a transient negative isotope excursion, which significantly differs from the positive isotope excursions observed in the Portland, Pont d'Issole, and Eastbourne records. A decrease in the magnitude of the carbonate fractionation factor provides the best explanation for a positive shift in δ44/40Ca values, especially given the rapid nature of the excursion. Because a decrease in the fractionation factor corresponds to an increase in the Ca/CO3 ratio of seawater, we tentatively attribute the positive Ca isotope excursion to transient ocean acidification, i.e., a reduction in the concentration of

  6. Electrostatic separation for recycling waste printed circuit board: a study on external factor and a robust design for optimization.

    PubMed

    Hou, Shibing; Wu, Jiang; Qin, Yufei; Xu, Zhenming

    2010-07-01

    Electrostatic separation is an effective and environmentally friendly method for recycling waste printed circuit board (PCB) by several kinds of electrostatic separators. However, some notable problems have been detected in its applications and cannot be efficiently resolved by optimizing the separation process. Instead of the separator itself, these problems are mainly caused by some external factors such as the nonconductive powder (NP) and the superficial moisture of feeding granule mixture. These problems finally lead to an inefficient separation. In the present research, the impacts of these external factors were investigated and a robust design was built to optimize the process and to weaken the adverse impact. A most robust parameter setting (25 kv, 80 rpm) was concluded from the experimental design. In addition, some theoretical methods, including cyclone separation, were presented to eliminate these problems substantially. This will contribute to efficient electrostatic separation of waste PCB and make remarkable progress for industrial applications.

  7. Cosmic ray isotopes

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1973-01-01

    The isotopic composition of cosmic rays is studied in order to develop the relationship between cosmic rays and stellar processes. Cross section and model calculations are reported on isotopes of H, He, Be, Al and Fe. Satellite instrument measuring techniques separate only the isotopes of the lighter elements.

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

    SciTech Connect

    Paulenova, Alena; Vandegrift, III, George F.

    2013-09-24

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

  9. 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.

  10. 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.

  11. Separable Sustained and Selective Attention Factors Are Apparent in 5-Year-Old Children

    PubMed Central

    Underbjerg, Mette; George, Melanie S.; Thorsen, Poul; Kesmodel, Ulrik S.; Mortensen, Erik L.; Manly, Tom

    2013-01-01

    In adults and older children, evidence consistent with relative separation between selective and sustained attention, superimposed upon generally positive inter-test correlations, has been reported. Here we examine whether this pattern is detectable in 5-year-old children from the healthy population. A new test battery (TEA-ChJ) was adapted from measures previously used with adults and older children and administered to 172 5-year-olds. Test-retest reliability was assessed in 60 children. Ninety-eight percent of the children managed to complete all measures. Discrimination of visual and auditory stimuli were good. In a factor analysis, the two TEA-ChJ selective attention tasks (one visual, one auditory) loaded onto a common factor and diverged from the two sustained attention tasks (one auditory, one motor), which shared a common loading on the second factor. This pattern, which suggests that the tests are indeed sensitive to underlying attentional capacities, was supported by the relationships between the TEA-ChJ factors and Test of Everyday Attention for Children subtests in the older children in the sample. It is possible to gain convincing performance-based estimates of attention at the age of 5 with the results reflecting a similar factor structure to that obtained in older children and adults. The results are discussed in light of contemporary models of attention function. Given the potential advantages of early intervention for attention difficulties, the findings are of clinical as well as theoretical interest. PMID:24376591

  12. Separable sustained and selective attention factors are apparent in 5-year-old children.

    PubMed

    Underbjerg, Mette; George, Melanie S; Thorsen, Poul; Kesmodel, Ulrik S; Mortensen, Erik L; Manly, Tom

    2013-01-01

    In adults and older children, evidence consistent with relative separation between selective and sustained attention, superimposed upon generally positive inter-test correlations, has been reported. Here we examine whether this pattern is detectable in 5-year-old children from the healthy population. A new test battery (TEA-Ch(J)) was adapted from measures previously used with adults and older children and administered to 172 5-year-olds. Test-retest reliability was assessed in 60 children. Ninety-eight percent of the children managed to complete all measures. Discrimination of visual and auditory stimuli were good. In a factor analysis, the two TEA-Ch(J) selective attention tasks (one visual, one auditory) loaded onto a common factor and diverged from the two sustained attention tasks (one auditory, one motor), which shared a common loading on the second factor. This pattern, which suggests that the tests are indeed sensitive to underlying attentional capacities, was supported by the relationships between the TEA-Ch(J) factors and Test of Everyday Attention for Children subtests in the older children in the sample. It is possible to gain convincing performance-based estimates of attention at the age of 5 with the results reflecting a similar factor structure to that obtained in older children and adults. The results are discussed in light of contemporary models of attention function. Given the potential advantages of early intervention for attention difficulties, the findings are of clinical as well as theoretical interest.

  13. Factors influencing separation distances against odour annoyance calculated by Gaussian and Lagrangian dispersion models

    NASA Astrophysics Data System (ADS)

    Piringer, Martin; Knauder, Werner; Petz, Erwin; Schauberger, Günther

    2016-09-01

    Direction-dependent separation distances to avoid odour annoyance, calculated with the Gaussian Austrian Odour Dispersion Model AODM and the Lagrangian particle diffusion model LASAT at two sites, are analysed and compared. The relevant short-term peak odour concentrations are calculated with a stability-dependent peak-to-mean algorithm. The same emission and meteorological data, but model-specific atmospheric stability classes are used. The estimate of atmospheric stability is obtained from three-axis ultrasonic anemometers using the standard deviations of the three wind components and the Obukhov stability parameter. The results are demonstrated for the Austrian villages Reidling and Weissbach with very different topographical surroundings and meteorological conditions. Both the differences in the wind and stability regimes as well as the decrease of the peak-to-mean factors with distance lead to deviations in the separation distances between the two sites. The Lagrangian model, due to its model physics, generally calculates larger separation distances. For worst-case calculations necessary with environmental impact assessment studies, the use of a Lagrangian model is therefore to be preferred over that of a Gaussian model. The study and findings relate to the Austrian odour impact criteria.

  14. The Influence of Kinetic Growth Factors on the Clumped Isotope Composition of Calcite

    NASA Astrophysics Data System (ADS)

    Hunt, J. D.; Watkins, J. M.; Tripati, A.; Ryerson, F. J.; DePaolo, D. J.

    2014-12-01

    Clumped isotope paleothermometry is based on the association of 13C and 18O within carbonate minerals. Although the influence of temperature on equilibrium 13C-18O bond ordering has been studied, recent oxygen isotope studies of inorganic calcite demonstrate that calcite grown in laboratory experiments and in many natural settings does not form in equilibrium with water. It is therefore likely that the carbon and clumped isotope composition of these calcite crystals are not representative of true thermodynamic equilibrium. To isolate kinetic clumped isotope effects that arise at the mineral-solution interface, clumped isotopic equilibrium of DIC species must be maintained. This can be accomplished by dissolving the enzyme carbonic anhydrase (CA) into the solution, thereby reducing the time required for isotopic equilibration of DIC species by approximately two orders of magnitude between pH 7.7 and 9.3. We conduct calcite growth experiments aimed specifically at measuring the pH-dependence of kinetic clumped isotope effects during non-equilibrium precipitation of calcite. We precipitated calcite from aqueous solution at a constant pH and controlled supersaturation over the pH range 7.7-9.3 in the presence of CA. For each experiment, a gas mixture of N2 and CO2 is bubbled through a beaker of solution without seed crystals. As CO2 from the gas dissolves into solution, calcite crystals grow on the beaker walls. The pH of the solution is maintained by use of an autotitrator with NaOH as the titrant. We control the temperature, pH, the pCO2 of the gas inflow, and the gas inflow rate, and monitor the total alkalinity, the pCO2 of the gas outflow, and the amount of NaOH added. A constant crystal growth rate of ~1.6 mmol/m2/hr is maintained over all experiments. Results from these experiments are compared to predictions from a recently-developed isotopic ion-by-ion growth model of calcite. The model describes the rate, temperature and pH dependence of oxygen isotope uptake

  15. Low-energy structure of the even-A {sup 96-104}Ru isotopes via g-factor measurements

    SciTech Connect

    Taylor, M. J.; Bentley, M. A.; Guerdal, G.; Kumbartzki, G.; Benczer-Koller, N.; Sharon, Y. Y.; Stuchbery, A. E.; Berant, Z.; Casperson, R. J.; Casten, R. F.; Heinz, A.; Ilie, G.; McCutchan, E. A.; Qian, J.; Werner, V.; Williams, E.; Winkler, R.; Luettke, R.; Shoraka, B.

    2011-04-15

    The transient-field-perturbed angular correlation technique was used with Coulomb excitation in inverse kinematics to perform a systematic measurement of the g factors of the first excited 2{sub 1}{sup +} states in the stable even-A isotopes {sup 96-104}Ru. The measurements have been made relative to one another under matched kinematic conditions and include a measurement of g(2{sub 1}{sup +})=+0.47(3) in {sup 96}Ru.

  16. Environmental site description for a Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) production plant at the Portsmouth Gaseous Diffusion Plant site

    SciTech Connect

    Marmer, G.J.; Dunn, C.P.; Filley, T.H.; Moeller, K.L.; Pfingston, J.M.; Policastro, A.J.; Cleland, J.H.

    1991-09-01

    Uranium enrichment in the United States has utilized a diffusion process to preferentially enrich the U-235 isotope in the uranium product. In the 1970s, the US Department of Energy (DOE) began investigating more efficient and cost-effective enrichment technologies. In January 1990, the Secretary of Energy approved a plan for the demonstration and deployment of the Uranium Atomic Vapor Laser isotope Separation (U-AVLIS) technology with the near-term goal to provide the necessary information to make a deployment decision by November 1992. Initial facility operation is anticipated for 1999. A programmatic document for use in screening DOE sites to locate a U-AVLIS production plant was developed and implemented in two parts. The first part consisted of a series of screening analyses, based on exclusionary and other criteria, that identified a reasonable number of candidate sites. The final evaluation, which included sensitivity studies, identified the Oak Ridge Gaseous Diffusion Plant (ORGDP) site, the Paducah Gaseous Diffusion Plant (PGDP) site, and the Portsmouth Gaseous Diffusion Plant (PORTS) site as having significant advantages over the other sites considered. This environmental site description (ESD) provides a detailed description of the PORTS site and vicinity suitable for use in an environmental impact statement (EIS). This report is based on existing literature, data collected at the site, and information collected by Argonne National Laboratory (ANL) staff during site visits. The organization of the ESD is as follows. Topics addressed in Sec. 2 include a general site description and the disciplines of geology, water resources, biotic resources, air resources, noise, cultural resources, land use. Socioeconomics, and waste management. Identification of any additional data that would be required for an EIS is presented in Sec. 3.

  17. METHOD OF ISOTOPE CONCENTRATION

    DOEpatents

    Spevack, J.S.

    1957-04-01

    An isotope concentration process is described which consists of exchanging, at two or more different temperature stages, two isotopes of an element between substances that are physically separate from each other and each of which is capable of containing either of the isotopes, and withdrawing from a point between at least two of the temperatare stages one of the substances containing an increased concentration of the desired isotope.

  18. Computational study on the progressive factorization of composite polymer knots into separated prime components.

    PubMed

    Tubiana, Luca

    2014-05-01

    Using Monte Carlo simulations and advanced knot localization methods, we analyze the length and distribution of prime components in composite knots tied on freely jointed rings. For increasing contour length, we observe the progressive factorization of composite knots into separated prime components. However, we observe that a complete factorization, equivalent to the "decorated ring" picture, is not obtained even for rings of contour lengths N ≃ 3 N(0), about tens of times the most probable length of the prime knots tied on the rings. The decorated ring hypothesis has been used in the literature to justify the factorization of composite knot probabilities into the knotting probabilities of their prime components. Following our results, we suggest that such a hypothesis may not be necessary to explain the factorization of the knotting probabilities, at least when polymers excluding volume is not relevant. We rationalize the behavior of the system through a simple one-dimensional model in which prime knots are replaced by slip links randomly placed on a circle, with the only constraint being that the length of the loops has the same distribution as that of the length of the corresponding prime knots.

  19. Alcohol fuel use: Implications for atmospheric levels of aldehydes, organic nitrates, pans, and peroxides: Separating sources using carbon isotopes

    SciTech Connect

    Gaffney, J.S.; Tanner, R.L.

    1988-01-01

    We have developed DiNitroPhenylHydrazone (DNPH) derivatization--high performance liquid chromatographic methods for measuring aldehydes in ambient samples with detection limits of approximately 1ppbV. These methods can be used for air or precipitation studies, and have been used for indoor measurements at much higher levels using shorter integration times. We are using gas chromatographs with electron capture detection (GCECD) to measure ambient levels of peroxyacyl nitrates and organic nitrates. Diffusion tubes with synthetically produced organic nitrates in n-tridecane solution are used to calibrate these systems. These compounds are important means of transporting NO/sub x/ over large scales due to their reduced tropospheric reactivity, low water solubilities, photolytic, and thermal stability. Their chemistries are coupled to aldehyde chemistry and are important greenhouse gases as well as phytotoxins. We have completed preliminary studies in Rio de Janeiro examining the atmospheric chemistry consequences of ethanol fuel usage. The urban air mass has been effected by the direct uncontrolled usage of ethanolgasoline and ethanoldiesel mixtures. We are exploring the use of luminol chemiluminescent detection of peroxides using gas chromatography to separate the various organic and inorganic peroxides. These compounds are coupled to the aldehyde chemistry, particularly in remote chemistries down-wind of urban sources. 13 refs.

  20. Simulating speleothem growth in the laboratory: Determination of stable isotope fractionation factors during precipitation of speleothem calcite

    NASA Astrophysics Data System (ADS)

    Hansen, Maximilian; Schöne, Bernd R.; Spötl, Christoph; Scholz, Denis

    2016-04-01

    We present laboratory experiments aiming to understand the processes affecting the δ13C and δ18O values of speleothems during precipitation of calcite from a thin layer of solution. In particular, we determined the precipitation rates and the isotope fractionation factors in dependence of several parameters, such as temperature, cave pCO2 and supersaturation with respect to calcite. The experiments were performed in a climate box in order to simulate cave conditions and to control them during the experiments[1]. In the experiments, a thin film of a CaCO3-CO2-H2O-solution supersaturated with respect to calcite flew down an inclined marble surface or a sand-blasted borosilicate glass plate, and the drip water was sampled at different distances and, thus, residence times on the plate. Subsequently, pH, electrical conductivity and the δ13C and δ18O values of the dissolved inorganic carbon (DIC) as well as the precipitated CaCO3 were determined. In addition, we determined the stable isotope values of the drip water and the atmosphere inside the box during the experiments. This enabled the identification of carbon and oxygen isotope fractionation factors between all carbonate species. The experiments were conducted at 10, 20 and 30 ° C, a pCO2 of 1000 and 3000 ppmV and with a Ca2+ concentration of 2 and 5 mmol/l. We observed an exponential decay of conductivity with increasing distance of flow documenting progressive precipitation of calcite confirming previous observations[2]. The corresponding time constants of precipitation range from 180 to 660 s. Both the δ13C and δ18O values show a progressive increase along the flow path. The enrichment of the δ13C values seems to be strongly influenced by kinetic isotope fractionation, whereas the δ18O values are in the range of isotopic equilibrium. The fractionation between the precipitated CaCO3 and DIC is between -1 and - 6.5 ‰ for carbon isotopes (13ɛ) and between -1.5 and -3 ‰ for oxygen isotopes (18ɛ). The

  1. Momentum transport cross-section measurements for potassium and rubidium in rare gases and white light-induced separation of rubidium isotopes

    SciTech Connect

    Mugglin, D.T.

    1993-12-31

    This dissertation is concerned with two light-induced kinetic effects, light-induced diffusive pulling and light-induced drift. We use a light-induced diffusive pulling experiment to measure the ground state velocity-changing collision cross section (related to the momentum transport cross section and the diffusion coefficient) and the relative difference ({Delta}{sigma}/{sigma}) of the excited and ground state cross sections with respect to that of the ground state for potassium mixed with inert buffer gases. The measured excited state cross section is a weighted average of the potassium 4{sup 2}P{sub 1/2} and 4{sup 2}P{sub 3/2} fine structure levels, which are mixed by collisions with inert gas atoms. For the ground state cross sections, we obtain the following experimental results for potassium mixed with He, Ne, Ar, Kr, and Xe, respectively: 52 {+-} 4, 57 {+-} 8, 61 {+-} 5, 43 {+-} 5, and 60 {+-}5 {angstrom}{sup 2}. For {Delta}{sigma}/{sigma}, we obtain the following (in the same order): 0.085 {+-} 0.010, 0.058 {+-} 0.006, 0.41 {+-} 0.03, 0.43 {+-} 0.03, and 0.61 {+-} 0.05. For potassium-Ne and potassium-Ar, we combine these measurements with light-induced drift measurements of the ratio {Delta}{sigma}(J = 3/2) : {Delta}{sigma}(J = 1/2) to obtain absolute transport cross sections for the individual 4{sup 2}S{sub 1/2}, 4{sup 2}P{sub 1/2}, and 4{sup 2}P{sub 3/2} levels. We also use the light-induced diffusive pulling experimental method to measure {Delta}{sigma}/{sigma} for Rb-inert gas mixtures. We obtain values for the ground state diffusion cross section for Rb in several of the inert gases as well. We report the first experimental observation of the separation of two isotopes using broadband light by the process of white light-induced drift. For a light source, we use a broadband laser with an acousto-optic modulator as an output coupler. We verify the separation of the {sup 85}Rb and {sup 87}Rb isotopes.

  2. Trophic Discrimination Factors and Incorporation Rates of Carbon- and Nitrogen-Stable Isotopes in Adult Green Frogs, Lithobates clamitans.

    PubMed

    Cloyed, Carl S; Newsome, Seth D; Eason, Perri K

    2015-01-01

    Stable isotope analysis is an increasingly useful ecological tool, but its accuracy depends on quantifying the tissue-specific trophic discrimination factors (TDFs) and isotopic incorporation rates for focal taxa. Despite the technique's ubiquity, most laboratory experiments determining TDFs and incorporation rates have focused on birds, mammals, and fish; we know little about terrestrial ectotherms, and amphibians in particular are understudied. In this study we used two controlled feeding experiments to determine carbon (δ(13)C) and nitrogen (δ(15)N) isotope TDFs for skin, whole blood, and bone collagen and incorporation rates for skin and whole blood in adult green frogs, Lithobates clamitans. The mean (±SD) TDFs for δ(13)C were 0.1‰ (±0.4‰) for skin, 0.5‰ (±0.5‰) for whole blood, and 1.6‰ (0.6‰) for bone collagen. The mean (±SD) TDFs for δ(15)N were 2.3‰ (±0.5‰) for skin, 2.3‰ (±0.4‰) for whole blood, and 3.1‰ (±0.6‰) for bone collagen. A combination of different isotopic incorporation models was best supported by our data. Carbon in skin was the only tissue in which incorporation was best explained by two compartments, which had half-lives of 89 and 8 d. The half-life of carbon in whole blood was 69 d. Half-lives for nitrogen were 75 d for skin and 71 d for whole blood. Our results help fill a taxonomic gap in our knowledge of stable isotope dynamics and provide ecologists with a method to measure anuran diets.

  3. The effect of environmental factors on stable isotopic composition of n-alkanes in Mediterranean olive oils

    NASA Astrophysics Data System (ADS)

    Pedentchouk, Nikolai; Mihailova, Alina; Abbado, Dimitri

    2014-05-01

    Traceability of the geographic origin of olive oils is an important issue from both commercial and health perspectives. This study evaluates the impact of environmental factors on stable C and H isotope compositions of n-alkanes in extra virgin olive oils from Croatia, France, Greece, Italy, Morocco, Portugal, Slovenia, and Spain. The data are used to investigate the applicability of stable isotope methodology for olive oil regional classification in the Mediterranean region. Analysis of stable C isotope composition of n-C29 alkane showed that extra virgin olive oils from Portugal and Spain have the most positive n-C29 alkane delta13C values. Conversely, olive oils from Slovenia, northern and central Italy are characterized by the most negative values. Overall, the n-C29 alkane delta13C values show a positive correlation with the mean air temperature during August-December and a negative correlation with the mean relative humidity during these months. Analysis of stable H isotope composition of n-C29 alkane revealed that the deltaD values are the most positive in olive oils from Greece and Morocco and the most negative in oils from northern Italy. The deltaD values of oils show significant correlation with all the analyses geographical parameters: the mean air temperature and relative humidity during August-December, the total amount of rainfall (the same months) and the annual deltaD values of precipitation. As predictor variables in the Categorical Data Analysis, the n-C29 alkane deltaD values show the most significant discriminative power, followed by the n-C29 alkane delta13C values. Overall, 93.4% of olive oil samples have been classified correctly into one of the production regions. Our findings suggest that an integrated analysis of C and H isotope compositions of n-alkanes extracted from extra virgin olive oil could become a useful tool for geographical provenancing of this highly popular food commodity.

  4. Factors That Contribute to the Improvement in Maternal Parenting after Separation from a Violent Husband or Partner

    ERIC Educational Resources Information Center

    Fujiwara, Takeo; Okuyama, Makiko; Izumi, Mayuko

    2012-01-01

    The authors test the hypothesis that separation from a violent husband or partner improves maternal parenting in Japan and examine how childhood abuse history (CAH), experience of domestic violence (DV), mental health problems, husband or partner's child maltreatment, and other demographic factors affect maternal parenting after such separation. A…

  5. Investigations of the g{sub K}-factors in the {sup 175,177,179}Hf Isotopes

    SciTech Connect

    Yakut, Hakan; Kuliev, Ali; Guliyev, Ekber

    2008-11-11

    In this paper the intrinsic g{sub K} and effective spin g{sub s} factors of the odd-mass {sup 175-179}Hf isotopes have been investigated within the Tamm-Dancoff approximation by using the realistic Saxon-Woods potential. The theoretically calculated g{sub K} and g{sub s}{sup eff} values are compared with experimental data. The comparison of the measured and calculated values of the effective g{sub s} factor shows that the spin polarization explains quite well the observed reduction of g{sub s} from its free-nucleon value.

  6. Methamphetamine reversed maternal separation-induced decrease in nerve growth factor in the ventral hippocampus.

    PubMed

    Dimatelis, J J; Russell, V A; Stein, D J; Daniels, W M

    2014-06-01

    Stress has been suggested to predispose individuals to drug abuse. The early life stress of maternal separation (MS) is known to alter the response to drugs of abuse later in life. Exposure to either stress or methamphetamine has been shown to alter neurotrophic factors in the brain. Changes in neurotrophin levels may contribute to the underlying molecular mechanisms responsible for drug use- and stress-induced behaviours. The purpose of the present study was to investigate the individual effects of MS and methamphetamine administration during adolescence and the combined effects of both stressors on brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) levels in the dorsal and ventral hippocampus (HC) in adulthood. Methamphetamine administration (1 mg/kg, daily from postnatal day (PND) 33 to 36 and from PND 39 to 42), MS and the combination of the two stressors resulted in decreased BDNF levels in both the dorsal and ventral HC. MS decreased NGF levels in the ventral HC which was restored by methamphetamine administration in adolescence. In the dorsal HC, NGF remained unaltered by either stressor alone or in combination. We propose that the restoration of NGF levels in the ventral HC may reflect a possible compensatory mechanism in response to methamphetamine exposure in adolescence following the early life stress of MS.

  7. Nonnegative signal factorization with learnt instrument models for sound source separation in close-microphone recordings

    NASA Astrophysics Data System (ADS)

    Carabias-Orti, Julio J.; Cobos, Máximo; Vera-Candeas, Pedro; Rodríguez-Serrano, Francisco J.

    2013-12-01

    Close-microphone techniques are extensively employed in many live music recordings, allowing for interference rejection and reducing the amount of reverberation in the resulting instrument tracks. However, despite the use of directional microphones, the recorded tracks are not completely free from source interference, a problem which is commonly known as microphone leakage. While source separation methods are potentially a solution to this problem, few approaches take into account the huge amount of prior information available in this scenario. In fact, besides the special properties of close-microphone tracks, the knowledge on the number and type of instruments making up the mixture can also be successfully exploited for improved separation performance. In this paper, a nonnegative matrix factorization (NMF) method making use of all the above information is proposed. To this end, a set of instrument models are learnt from a training database and incorporated into a multichannel extension of the NMF algorithm. Several options to initialize the algorithm are suggested, exploring their performance in multiple music tracks and comparing the results to other state-of-the-art approaches.

  8. Generic Uniqueness of a Structured Matrix Factorization and Applications in Blind Source Separation

    NASA Astrophysics Data System (ADS)

    Domanov, Ignat; Lathauwer, Lieven De

    2016-06-01

    Algebraic geometry, although little explored in signal processing, provides tools that are very convenient for investigating generic properties in a wide range of applications. Generic properties are properties that hold "almost everywhere". We present a set of conditions that are sufficient for demonstrating the generic uniqueness of a certain structured matrix factorization. This set of conditions may be used as a checklist for generic uniqueness in different settings. We discuss two particular applications in detail. We provide a relaxed generic uniqueness condition for joint matrix diagonalization that is relevant for independent component analysis in the underdetermined case. We present generic uniqueness conditions for a recently proposed class of deterministic blind source separation methods that rely on mild source models. For the interested reader we provide some intuition on how the results are connected to their algebraic geometric roots.

  9. 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?

    SciTech Connect

    van Soest, M.C.; Kennedy, B.M.; Evans, W.C.; Mariner, R.H.

    2002-04-30

    Cold bubbling springs in the Separation Creek area, the locus of current uplift at South Sister volcano show strong mantle signatures in helium and carbon isotopes and CO{sub 2}/{sup 3}He. This suggests the presence of fresh basaltic magma in the volcanic plumbing system. Currently there is no evidence to link this system directly to the uplift, which started in 1998. To the contrary, all geochemical evidence suggests that there is a long-lived geothermal system in the Separation Creek area, which has not significantly changed since the early 1990s. There was no archived helium and carbon data, so a definite conclusion regarding the strong mantle signature observed in these tracers cannot yet be drawn. There is a distinct discrepancy between the yearly magma supply required to explain the current uplift (0.006 km{sup 3}/yr) and that required to explain the discharge of CO{sub 2} from the system (0.0005 km{sup 3}/yr). This discrepancy may imply that the chemical signal associated with the increase in magma supply has not reached the surface yet. With respect to this the small changes observed at upper Mesa Creek require further attention, due to the recent volcanic vent in that area it may be the location were the chemical signal related to the uplift can most quickly reach the surface. Occurrence of such strong mantle signals in cold/diffuse geothermal systems suggests that these systems should not be ignored during volcano monitoring or geothermal evaluation studies. Although the surface-expression of these springs in terms of heat is minimal, the chemistry carries important information concerning the size and nature of the underlying high-temperature system and any changes taking place in it.

  10. Single-tube, non-isotopic, multiplex PCR/OLA assay and sequence-coded separation for simultaneous screening of 31 cystic fibrosis mutations

    SciTech Connect

    Brinson, E.C.; Adriano, T.; Bloch, W.

    1994-09-01

    We have developed a rapid, single-tube, non-isotopic assay that screens a patient sample for the presence of 31 cystic fibrosis (CF) mutations. This assay can identify these mutations in a single reaction tube and a single electrophoresis run. Sample preparation is a simple, boil-and-go procedure, completed in less than an hour. The assay is composed of a 15-plex PCR, followed by a 61-plex oligonucleotide ligation assay (OLA), and incorporates a novel detection scheme, Sequence Coded Separation. Initially, the multiplex PCR amplifies 15 relevant segments of the CFTR gene, simultaneously. These PCR amplicons serve as templates for the multiplex OLA, which detects the normal or mutant allele at all loci, simultaneously. Each polymorphic site is interrogated by three oligonucleotide probes, a common probe and two allele-specific probes. Each common probe is tagged with a fluorescent dye, and the competing normal and mutant allelic probes incorporate different, non-nucleotide, mobility modifiers. These modifiers are composed of hexaethylene oxide (HEO) units, incorporated as HEO phosphoramidite monomers during automated DNA synthesis. The OLA is based on both probe hybridization and the ability of DNA ligase to discriminate single base mismatches at the junction between paired probes. Each single tube assay is electrophoresed in a single gel lane of a 4-color fluorescent DNA sequencer (Applied Biosystems, Model 373A). Each of the ligation products is identified by its unique combination of electrophoretic mobility and one of three colors. The fourth color is reserved for the in-lane size standard, used by GENESCAN{sup TM} software (Applied Biosystems) to size the OLA electrophoresis products. The Genotyper{sub TM} software (Applied Biosystems) decodes these Sequence-Coded-Separation data to create a patient summary report for all loci tested.

  11. Determination of Os by isotope dilution-inductively coupled plasma-mass spectrometry with the combination of laser ablation to introduce chemically separated geological samples

    NASA Astrophysics Data System (ADS)

    Sun, Yali; Ren, Minghao; Xia, Xiaoping; Li, Congying; Sun, Weidong

    2015-11-01

    A method was developed for the determination of trace Os in geological samples by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) with the combination of chemical separation and preconcentration. Samples are digested using aqua regia in Carius tubes, and the Os analyte is converted into volatile OsO4, which is distilled and absorbed with HBr. The HBr solution is concentrated for further Os purification using the microdistillation technique. The purified Os is dissolved in 10 μl of 0.02% sucrose-0.005% H3PO4 solution and then evaporated on pieces of perfluoroalkoxy (PFA) film, resulting in the formation of a tiny object (< 3 × 104 μm2 superficial area). Using LA-ICP-MS measurements, the object can give Os signals at least 100 times higher than those provided by routine solution-ICP-MS while successfully avoiding the memory effect. The procedural blank and detection limit in the developed technique are 3.0 pg and 1.8 pg for Os, respectively when 1 g of samples is taken. Reference materials (RM) are analyzed, and their Os concentrations obtained by isotope dilution are comparable to reference or literature values. Based on the individual RM results, the precision is estimated within the range of 0.6 to 9.4% relative standard deviation (RSD), revealing that this method is applicable to the determination of trace Os in geological samples.

  12. Direct measurement of the boron isotope fractionation factor: Reducing the uncertainty in reconstructing ocean paleo-pH

    NASA Astrophysics Data System (ADS)

    Nir, Oded; Vengosh, Avner; Harkness, Jennifer S.; Dwyer, Gary S.; Lahav, Ori

    2015-03-01

    The boron isotopic composition of calcium carbonate skeletons is a promising proxy method for reconstructing paleo-ocean pH and atmospheric CO2 from the geological record. Although the boron isotope methodology has been used extensively over the past two decades to determine ancient ocean-pH, the actual value of the boron isotope fractionation factor (εB) between the two main dissolved boron species, 11B(OH)3 and 10B(OH)-4, has remained uncertain. Initially, εB values were theoretically computed from vibrational frequencies of boron species, resulting in a value of ∼ 19 ‰. Later, spectrophotometric pH measurements on artificial seawater suggested a higher value of ∼ 27 ‰. A few independent theoretical models also pointed to a higher εB value. Here we provide, for the first time, an independent empirical fractionation factor (εB = 26.0 ± 1.0 ‰ ; 25 °C), determined by direct measurements of B(OH)3 in seawater and other solutions. Boric acid was isolated by preferential passage through a reverse osmosis membrane under controlled pH conditions. We further demonstrate that applying the Pitzer ion-interaction approach, combined with ion-pairing calculations, results in a more accurate determination of species distribution in aquatic solutions of different chemical composition, relative to the traditional two-species boron-system approach. We show that using the revised approach reduces both the error in simulating ancient atmospheric CO2 (by up to 21%) and the overall uncertainty of applying boron isotopes for paleo-pH reconstruction. Combined, this revised methodology lays the foundation for a more accurate determination of ocean paleo-pH through time.

  13. 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.

  14. The use of Alpert-Stein Factor Separation Methodology for climate variable interaction studies in hydrological land surface models and crop yield models. In:Factor Separation in the Atmosphere:Application and future prospects

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The Factor Separation Method (FacSep) is a modeling application that has been utilized in the study of biophysical responses to changes in the environment to assess the relative contribution of different atmospheric factors on a biological system. In this chapter we will discuss crop simulation and...

  15. Uranium isotopic fractionation factors during U(VI) reduction by bacterial isolates

    NASA Astrophysics Data System (ADS)

    Basu, Anirban; Sanford, Robert A.; Johnson, Thomas M.; Lundstrom, Craig C.; Löffler, Frank E.

    2014-07-01

    We experimentally determined the magnitude of uranium isotopic fractionation induced by U(VI) reduction by metal reducing bacterial isolates. Our results indicate that microbial U(VI) reduction induces isotopic fractionation; heavier isotopes (i.e., 238U) partition into the solid U(IV) products. The magnitudes of isotopic fractionation (expressed as ε = 1000‰ * (α-1)) for 238U/235U were 0.68‰ ± 0.05‰ and 0.99‰ ± 0.12‰ for Geobacter sulfurreducens strain PCA and strain IFRC-N, respectively. The ε values for Anaeromyxobacter dehalogenans strain FRC-W, strain FRC-R5, a novel Shewanella isolate, and Desulfitobacterium sp. strain Viet1 were 0.72‰ ± 0.15‰, 0.99‰ ± 0.12‰, 0.96‰ ± 0.16‰ and 0.86‰ ± 0.06‰, respectively. Our results show that the maximum ε values of ∼1.0‰ were obtained with low biomass (∼107 cells/mL) and low electron donor concentrations (∼500 μM). These results provide an initial assessment of 238U/235U shifts induced by microbially-mediated U(VI) reduction, which is needed as 238U/235U data are increasingly applied as redox indicators in various geochemical settings.

  16. Dietary shift after 3600 cal yr BP and its influencing factors in northwestern China: Evidence from stable isotopes

    NASA Astrophysics Data System (ADS)

    Ma, Minmin; Dong, Guanghui; Jia, Xin; Wang, Hui; Cui, Yifu; Chen, Fahu

    2016-08-01

    Human diets rely on natural resource availability and can reflect social and cultural values. When environments, societies, and cultures change, diets may also shift. This study traced the extent of dietary change and the factors influencing such change. Through stable carbon and nitrogen isotopic analysis of late Neolithic and early Bronze Age human and animal bone collagen, we found that significant shifts in human diets were closely associated with intercontinental cultural exchanges in Eurasia and climate change in northwestern China. The isotopic evidence indicated that human diets mainly consisted of C4 foodstuffs (presumably millet and/or animals fed with C4 foods) around 4000 calibrated years before the present (cal yr BP), corresponding to the flourishing of millet agriculture in the context of the optimal climate conditions of the mid-Holocene. Subsequently, more C3 foods (probably wheat, barley, and animals fed with C3 foods) were added to human diets post-3600 cal yr BP when the climate became cooler and drier. Such dietary variation is also consistent with the increasing intensity of long-distance exchange after 4000 cal yr BP. While many factors can lead to human dietary shifts (e.g. climate change, population growth, cultural factors, and human migration), climate may have been a key factor in Gansu and Qinghai.

  17. Impact of CO2 and climate on Last Glacial maximum vegetation - a factor separation

    NASA Astrophysics Data System (ADS)

    Claussen, M.; Selent, K.; Brovkin, V.; Raddatz, T.; Gayler, V.

    2013-06-01

    The factor separation of Stein and Alpert (1993) is applied to simulations with the MPI Earth system model to determine the factors which cause the differences between vegetation patterns in glacial and pre-industrial climate. The factors firstly include differences in the climate, caused by a strong increase in ice masses and the radiative effect of lower greenhouse gas concentrations; secondly, differences in the ecophysiological effect of lower glacial atmospheric CO2 concentrations; and thirdly, the synergy between the pure climate effect and the pure effect of changing physiologically available CO2. It is has been shown that the synergy can be interpreted as a measure of the sensitivity of ecophysiological CO2 effect to climate. The pure climate effect mainly leads to a contraction or a shift in vegetation patterns when comparing simulated glacial and pre-industrial vegetation patterns. Raingreen shrubs benefit from the colder and drier climate. The pure ecophysiological effect of CO2 appears to be stronger than the pure climate effect for many plant functional types - in line with previous simulations. The pure ecophysiological effect of lower CO2 mainly yields a reduction in fractional coverage, a thinning of vegetation and a strong reduction in net primary production. The synergy appears to be as strong as each of the pure contributions locally, but weak on global average for most plant functional types. For tropical evergreen trees, however, the synergy is strong on global average. It diminishes the difference between glacial and pre-industrial coverage of tropical evergreen trees, due to the pure climate effect and the pure ecophysiological CO2 effect, by approximately 50 per cent.

  18. Factors influence flexibility resistivity and zinc dendrite penetration rate of inorganic separators for alkaline batteries

    NASA Technical Reports Server (NTRS)

    Sheibley, D. W.

    1975-01-01

    Developmental work resulted in a formulation which can improve the flexibility of the inorganic-organic-type separator for silver-zinc and nickel-zinc alkaline batteries. The effects of various fillers and reactive organic additives on separator volume resistivity are described. The effects of various inert fillers on the zinc dendrite penetration rate of the separator are shown. Conclusions regarding the operating mechanism of the separator are presented.

  19. Generation of Radixenon Isotopes

    SciTech Connect

    McIntyre, Justin I.; Bowyer, Ted W.; Hayes, James C.; Heimbigner, Tom R.; Morris, Scott J.; Panisko, Mark E.; Pitts, W. K.; Pratt, Sharon L.; Reeder, Paul L.; Thomas, Charles W.

    2003-06-30

    Pacific Northwest National Laboratory has developed an automated system for separating Xe from air and can detect the following radioxenon isotopes, 131mXe, 133mXe, 133Xe, and 135Xe. This report details the techniques used to generate the various radioxenon isotopes that are used for the calibration of the detector as well as other isotopes that have the potential to interfere with the fission produced radioxenon isotopes. Fission production is covered first using highly enriched uranium followed by a description and results from an experiment to produce radioxenon isotopes from neutron activation of ambient xenon.

  20. 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.

  1. [Hyperspectral Band Selection Based on Spectral Clustering and Inter-Class Separability Factor].

    PubMed

    Qin, Fang-pu; Zhang, Ai-wu; Wang, Shu-min; Meng, Xian-gang; Hu, Shao-xing; Sun, Wei-dong

    2015-05-01

    With the development of remote sensing technology and imaging spectrometer, the resolution of hyperspectral remote sensing image has been continually improved, its vast amount of data not only improves the ability of the remote sensing detection but also brings great difficulties for analyzing and processing at the same time. Band selection of hyperspectral imagery can effectively reduce data redundancy and improve classification accuracy and efficiency. So how to select the optimum band combination from hundreds of bands of hyperspectral images is a key issue. In order to solve these problems, we use spectral clustering algorithm based on graph theory. Firstly, taking of the original hyperspectral image bands as data points to be clustered , mutual information between every two bands is calculated to generate the similarity matrix. Then according to the graph partition theory, spectral decomposition of the non-normalized Laplacian matrix generated by the similarity matrix is used to get the clusters, which the similarity between is small and the similarity within is large. In order to achieve the purpose of dimensionality reduction, the inter-class separability factor of feature types on each band is calculated, which is as the reference index to choose the representative bands in the clusters furthermore. Finally, the support vector machine and minimum distance classification methods are employed to classify the hyperspectral image after band selection. The method in this paper is different from the traditional unsupervised clustering method, we employ spectral clustering algorithm based on graph theory and compute the interclass separability factor based on a priori knowledge to select bands. Comparing with traditional adaptive band selection algorithm and band index based on automatically subspace divided algorithm, the two sets of experiments results show that the overall accuracy of SVM is about 94. 08% and 94. 24% and the overall accuracy of MDC is about 87

  2. Processing factors that influence casein and serum protein separation by microfiltration.

    PubMed

    Hurt, E; Barbano, D M

    2010-10-01

    Our objective was to demonstrate the effect of various processing factors on the performance of a microfiltration system designed to process skim milk and separate casein (CN) from serum proteins (SP). A mathematical model of a skim milk microfiltration process was developed with 3 stages plus an additional fourth finishing stage to standardize the retentate to 9% true protein (TP) and allow calculation of yield of a liquid 9% TP micellar CN concentrate (MCC) and milk SP isolate (MSPI; 90% SP on a dry basis). The model was used to predict the effect of 5 factors: 1) skim milk composition, 2) heat treatment of skim milk, 3) concentration factor (CF) and diafiltration factor (DF), 4) control of CF and DF, and 5) SP rejection by the membrane on retentate and permeate composition, SP removal, and MCC and MSPI yield. When skim milk TP concentration increased from 3.2 to 3.8%, the TP concentration in the third stage retentate increased from 7.92 to 9.40%, the yield of MCC from 1,000 kg of skim milk increased from 293 to 348 kg, and the yield of MSPI increased from 6.24 to 7.38 kg. Increased heat treatment (72.9 to 85.2°C) of skim milk caused the apparent CN as a percentage of TP content of skim milk as measured by Kjeldahl analysis to increase from 81.97 to 85.94% and the yield of MSPI decreased from 6.24 to 4.86 kg, whereas the third stage cumulative percentage SP removal decreased from 96.96 to 70.08%. A CF and DF of 2× gave a third stage retentate TP concentration of 5.38% compared with 13.13% for a CF and DF of 5×, with the third stage cumulative SP removal increasing from 88.66 to 99.47%. Variation in control of the balance between CF and DF (instead of an equal CF and DF) caused either a progressive increase or decrease in TP concentration in the retentate across stages depending on whether CF was greater than DF (increasing TP in retentate) or CF was less than DF (decreasing TP in retentate). An increased rejection of SP by the membrane from an SP removal

  3. Environmental site description for a Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) production plant at the Oak Ridge Gaseous Diffusion Plant Site

    SciTech Connect

    Not Available

    1991-09-01

    In January 1990, the Secretary of Energy approved a plan for the demonstration and deployment of the Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) technology, with the near-term goal to provide the necessary information to make a deployment decision by November 1992. The U-AVLIS process is based on electrostatic extraction of photoionized U-235 atoms from an atomic vapor stream created by electron-beam vaporization of uranium metal alloy. A programmatic document for use in screening DOE sites to locate the U-AVLIS production plant was developed and implemented in two parts (Wolsko et al. 1991). The first part consisted of a series of screening analyses, based on exclusionary and other criteria, that identified a reasonable number of candidate sites. These sites were then subjected to a more rigorous and detailed comparative analysis for the purpose of developing a short list of reasonable alternative sites for later environmental examination. This environmental site description (ESD) provides a detailed description of the ORGDP site and vicinity suitable for use in an environmental impact statement (EIS). The report is based on existing literature, data collected at the site, and information collected by Argonne National Laboratory (ANL) staff during a site visit. The organization of the ESD is as follows. Topics addressed in Sec. 2 include a general site description and the disciplines of geology, water resources, biotic resources, air resources, noise, cultural resources, land use, socioeconomics, and waste management. Identification of any additional data that would be required for an EIS is presented in Sec. 3. Following the site description and additional data requirements, Sec. 4 provides a short, qualitative assessment of potential environmental issues. 37 refs., 20 figs., 18 tabs.

  4. Strong anion exchange liquid chromatographic separation of protein amino acids for natural 13C-abundance determination by isotope ratio mass spectrometry.

    PubMed

    Abaye, Daniel A; Morrison, Douglas J; Preston, Tom

    2011-02-15

    Amino acids are the building blocks of proteins and the analysis of their (13)C abundances is greatly simplified by the use of liquid chromatography (LC) systems coupled with isotope ratio mass spectrometry (IRMS) compared with gas chromatography (GC)-based methods. To date, various cation exchange chromatography columns have been employed for amino acid separation. Here, we report strong anion exchange chromatography (SAX) coupled to IRMS with a Liquiface interface for amino acid δ(13)C determination. Mixtures of underivatised amino acids (0.1-0.5 mM) and hydrolysates of representative proteins (prawns and bovine serum albumin) were resolved by LC/IRMS using a SAX column and inorganic eluents. Background inorganic carbon content was minimised through careful preparation of alkaline reagents and use of a pre-injector on-line carbonate removal device. SAX chromatography completely resolved 11 of the 16 expected protein amino acids following acid hydrolysis in underivatised form. Basic and neutral amino acids were resolved with 35 mM NaOH in isocratic mode. Elution of the aromatic and acidic amino acids required a higher hydroxide concentration (180 mM) and a counterion (NO 3-, 5-25 mM). The total run time was 70 min. The average δ(13)C precision of baseline-resolved peaks was 0.75‰ (range 0.04 to 1.06‰). SAX is a viable alternative to cation chromatography, especially where analysis of basic amino acids is important. The technology shows promise for (13)C amino acid analysis in ecology, archaeology, forensic science, nutrition and protein metabolism.

  5. Dietary restriction: critical co-factors to separate health span from life span benefits.

    PubMed

    Mendelsohn, Andrew R; Larrick, James W

    2012-10-01

    Dietary restriction (DR), typically a 20%-40% reduction in ad libitum or "normal" nutritional energy intake, has been reported to extend life span in diverse organisms, including yeast, nematodes, spiders, fruit flies, mice, rats, and rhesus monkeys. The magnitude of the life span enhancement appears to diminish with increasing organismal complexity. However, the extent of life span extension has been notoriously inconsistent, especially in mammals. Recently, Mattison et al. reported that DR does not extend life span in rhesus monkeys in contrast to earlier work of Colman et al. Examination of these papers identifies multiple potential confounding factors. Among these are the varied genetic backgrounds and composition of the "normal" and DR diets. In monkeys, the correlation of DR with increased health span is stronger than that seen with life span and indeed may be separable. Recent mechanistic studies in Drosophila implicate non-genetic co-factors such as level of physical activity and muscular fatty acid metabolism in the benefits of DR. These results should be followed up in mammals. Perhaps levels of physical activity among the cohorts of rhesus monkeys contribute to inconsistent DR effects. To understand the maximum potential benefits from DR requires differentiating fundamental effects on aging at the cellular and molecular levels from suppression of age-associated diseases, such as cancer. To that end, it is important that investigators carefully evaluate the effects of DR on biomarkers of molecular aging, such as mutation rate and epigenomic alterations. Several short-term studies show that humans may benefit from DR in as little as 6 months, by achieving lowered fasting insulin levels and improved cardiovascular health. Optimized health span engineering will require a much deeper understanding of DR.

  6. Impact of CO2 and climate on Last Glacial Maximum vegetation - a factor separation

    NASA Astrophysics Data System (ADS)

    Claussen, M.; Selent, K.; Brovkin, V.; Raddatz, T.; Gayler, V.

    2012-11-01

    Differences between glacial and pre-industrial potential vegetation patterns can conceptually be attributed to two factors: firstly to differences in the climate, caused by a strong increase in ice masses and the radiative effect of lower greenhouse gas concentrations, and secondly to differences in the ecophysiological effect of lower glacial atmospheric CO2 concentrations. The synergy emerging from these effects when operating simultaneously can be interpreted as sensitivity of the effect of enhancing physiologically available CO2 on shifting vegetation to climate warming. Alternatively and equally valid, it can be viewed as sensitivity of climatically induced vegetation changes to differences in physiologically available CO2. A first complete factor separation based on simulations with the MPI Earth System Model indicates that the pure climate effect mainly leads to a contraction or a shift in vegetation patterns when comparing glacial with pre-industrial simulation vegetation patterns. Globally, a reduction in fractional coverage of most plant functional types is seen - except for raingreen shrubs which strongly benefit from the colder and drier climate. The ecophysiological effect of CO2 appears to be stronger than the pure climate contribution for many plant functional types - in line with previous simulations. The ecophysiological effect of lower CO2 mainly yields a reduction in fractional coverage, a thinning of vegetation and a strong reduction in net primary production. The synergy appears to be as strong as each of the pure contributions locally. For tropical evergreen trees, the synergy appears strong also on global average. Hence this modelling study suggests that for tropical forests, an increase in CO2 has, on average, a stronger ecophysiological effect in warmer climate than in glacial climate. Alternatively, areal differences in tropical forests induced by climate warming can, on average, be expected to be larger with increasing concentration of

  7. [Separation of coagulation factor VIII with high activity using gigaporous anion exchange chromatography].

    PubMed

    Kang, Limei; Zhang, Yan; Luo, Jian; Li, You; Zhou, Yuefang; Yu, Rong; Su, Zhiguo

    2012-06-01

    A purification process to obtain coagulation factor VIII (F VIII) with high activity from human plasma was established. Based on the analysis of the size ratio between F VIII and matrix porous medium and its effect on the protein activity, a novel purification process designed was superporous ion exchange chromatography (IEC). The operating conditions of gigaporous and traditional anion exchange chromatography were optimized separately. The chromogenic substrate, gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were used to monitor the bioactivity and purity of the chromatographic products. The results showed that the superporous medium could not only protect structure of macro-protein but also enhance its mass transfer, finally giving FVIII product with high activity. The yield of F VIII in superporous chromatography was about five times of commercially agarose chromatography and the specific activity was up to 154 IU/mg protein. Furthermore, we studied the regeneration process of the superporous medium, washing the column with 5 column volumes of 1 mol/L NaOH at a low flow rate, to ensure the chromatographic stability. This purification process is simple, reproducible and suitable for large-scale production.

  8. A Survey of Factors Affecting Blunt Leading-Edge Separation for Swept and Semi-Slender Wings

    NASA Technical Reports Server (NTRS)

    Luckring, James M.

    2010-01-01

    A survey is presented of factors affecting blunt leading-edge separation for swept and semi-slender wings. This class of separation often results in the onset and progression of separation-induced vortical flow over a slender or semi-slender wing. The term semi-slender is used to distinguish wings with moderate sweeps and aspect ratios from the more traditional highly-swept, low-aspect-ratio slender wing. Emphasis is divided between a selection of results obtained through literature survey a section of results from some recent research projects primarily being coordinated through NATO s Research and Technology Organization (RTO). An aircraft context to these studies is included.

  9. Stable isotope composition in Daphnia is modulated by growth, temperature, and toxic exposure: implications for trophic magnification factor assessment.

    PubMed

    Ek, Caroline; Karlson, Agnes M L; Hansson, Sture; Garbaras, Andrius; Gorokhova, Elena

    2015-06-02

    The potential for using stable isotope analysis in risk assessment of environmental contaminants is crucially dependent on the predictability of the trophic transfer of isotopes in food webs. The relationship between contaminant levels and trophic position of consumers is widely used to assess biomagnification properties of various pollutants by establishing trophic magnification factors (TMF). However, contaminant-induced variability of the isotopic composition in biota is poorly understood. Here, we investigated effects of toxic exposure on δ(15)N and δ(13)C values in a consumer, with a main hypothesis that these effects would be largely mediated via growth rate and metabolic turnover of the test animals. The cladoceran Daphnia magna was used in two experiments that were conducted to manipulate growth and body condition (assayed as C:N ratio) by food availability and temperature (Experiment 1) and by toxic exposure to the pesticide lindane (Experiment 2). We found a significant negative effect of growth rate and a positive effect of temperature on the consumer-diet discrimination factor for δ(15)N and δ(13)C, with no effects on the C:N ratio (Experiment 1). In lindane-exposed daphnids, a significant growth inhibition was observed, with concomitant increase in metabolic costs and significantly elevated size-specific δ(15)N and δ(13)C values. Moreover, a significantly higher incorporation of carbon relative to nitrogen, yet a concomitant decrease in C:N ratio was observed in the exposed animals. Together, these results have methodological implications for determining trophic positions and TMF in polluted environments, where elevated δ(15)N values would translate into overestimated trophic positions and underestimated TMF. Furthermore, altered δ(13)C values may lead to erroneous food-chain assignment of the consumer in question.

  10. Onflow liquid chromatography at critical conditions coupled to (1)H and (2)H nuclear magnetic resonance as powerful tools for the separation of poly(methylmethacrylate) according to isotopic composition.

    PubMed

    Hehn, Mathias; Sinha, Pritish; Pasch, Harald; Hiller, Wolf

    2015-03-27

    The present work addresses a major challenge in polymer chromatography by developing a method to separate and analyze polymers with identical molar masses, chemical structures and tacticities that is solely based on differences in isotope composition. For the first time, liquid chromatography at critical conditions (LCCC) was used to separate PMMA regarding the H and D isotopes. At critical conditions of H-PMMA, D-PMMA eluted in the adsorption mode and vice versa. By online onflow LCCC-NMR, both PMMA species were clearly identified. Different from other detectors, NMR can distinguish between H and D. Onflow LCCC-H/NMR and LCCC-D/NMR measurements were carried out and the H/D-blend components were detected. (1)H and (13)C NMR provided the tacticity of protonated PMMA. Double resonance (13)C{H} and triple resonance (13)C{H,D} provided the tacticity of the deuterated samples. Samples with similar tacticities were used to ensure that separation occurs solely regarding the isotope labeling.

  11. The key factor limiting plant growth in cold and humid alpine areas also plays a dominant role in plant carbon isotope discrimination.

    PubMed

    Xu, Meng; Wang, Guoan; Li, Xiaoliang; Cai, Xiaobu; Li, Xiaolin; Christie, Peter; Zhang, Junling

    2015-01-01

    Many environmental factors affect carbon isotope discrimination in plants, yet the predominant factor influencing this process is generally assumed to be the key growth-limiting factor. However, to our knowledge this hypothesis has not been confirmed. We therefore determined the carbon isotope composition (δ(13)C) of plants growing in two cold and humid mountain regions where temperature is considered to be the key growth-limiting factor. Mean annual temperature (MAT) showed a significant impact on variation in carbon isotope discrimination value (Δ) irrespective of study area or plant functional type with either partial correlation or regression analysis, but the correlation between Δ and soil water content (SWC) was usually not significant. In multiple stepwise regression analysis, MAT was either the first or the only variable selected into the prediction model of Δ against MAT and SWC, indicating that the effect of temperature on carbon isotope discrimination was predominant. The results therefore provide evidence that the key growth-limiting factor is also crucial for plant carbon isotope discrimination. Changes in leaf morphology, water viscosity and carboxylation efficiency with temperature may be responsible for the observed positive correlation between Δ and temperature.

  12. Psychological Factors Capable of Preventing the Inhibition of Antibody Responses in Separated Infant Monkeys.

    ERIC Educational Resources Information Center

    Coe, Christopher L.; And Others

    1987-01-01

    Capacity of infant monkeys to mount an antibody response to viral challenge was evaluated after monkeys' removal from their mothers in several social and physical environments. Results indicated that trauma of separation was reduced when infants were familiar with the separation environment or familiar social companions were available. (PCB)

  13. Separation as an Important Risk Factor for Suicide: A Systematic Review

    ERIC Educational Resources Information Center

    Ide, Naoko; Wyder, Marianne; Kolves, Kairi; De Leo, Diego

    2010-01-01

    Examining how different phases of relationship separation effects the development of suicidal behaviors has been largely ignored in suicide studies. The few studies conducted suggest that individuals experiencing the acute phase of marital/de facto separation may be at greater risk of suicide compared with those experiencing long-term separation…

  14. Blind source separation for groundwater pressure analysis based on nonnegative matrix factorization

    NASA Astrophysics Data System (ADS)

    Alexandrov, Boian S.; Vesselinov, Velimir V.

    2014-09-01

    The identification of the physical sources causing spatial and temporal fluctuations of aquifer water levels is a challenging, yet a very important hydrogeological task. The fluctuations can be caused by variations in natural and anthropogenic sources such as pumping, recharge, barometric pressures, etc. The source identification can be crucial for conceptualization of the hydrogeological conditions and characterization of aquifer properties. We propose a new computational framework for model-free inverse analysis of pressure transients based on Nonnegative Matrix Factorization (NMF) method for Blind Source Separation (BSS) coupled with k-means clustering algorithm, which we call NMFk. NMFk is capable of identifying a set of unique sources from a set of experimentally measured mixed signals, without any information about the sources, their transients, and the physical mechanisms and properties controlling the signal propagation through the subsurface flow medium. Our analysis only requires information about pressure transients at a number of observation points, m, where m≥r, and r is the number of unknown unique sources causing the observed fluctuations. We apply this new analysis on a data set from the Los Alamos National Laboratory site. We demonstrate that the sources identified by NMFk have real physical origins: barometric pressure and water-supply pumping effects. We also estimate the barometric pressure efficiency of the monitoring wells. The possible applications of the NMFk algorithm are not limited to hydrogeology problems; NMFk can be applied to any problem where temporal system behavior is observed at multiple locations and an unknown number of physical sources are causing these fluctuations.

  15. Factors controlling the growth rate, carbon and oxygen isotope variation in modern calcite precipitation in a subtropical cave, Southwest China

    NASA Astrophysics Data System (ADS)

    Pu, Junbing; Wang, Aoyu; Shen, Licheng; Yin, Jianjun; Yuan, Daoxian; Zhao, Heping

    2016-04-01

    A prerequisite for using cave speleothems to reconstruct palaeoenvironmental conditions is an accurate understanding of specific factors controlling calcite growth, in particular the isotopic partitioning of oxygen (δ18O) and carbon (δ13C) which are the most commonly used proxies. An in situ monitoring study from April 2008 to September 2009 at Xueyu Cave, Chongqing, SW China, provides insight into the controls on calcite growth rates, drip water composition, cave air parameters and δ18O and δ13C isotopic values of modern calcite precipitation. Both cave air PCO2 and drip water hydrochemical characteristics show obvious seasonality driven by seasonal changes in the external environment. Calcite growth rates also display clear intra-annual variation, with the lowest values occurring during wet season and peak values during the dry season. Seasonal variations of calcite growth rate are primarily controlled by variations of cave air PCO2 and drip water rate. Seasonal δ18O-VPDB and δ13C-VPDB in modern calcite precipitates vary, with more negative values in the wet season than in the dry season. Strong positive correlation of δ18O-VPDB vs. δ13C-VPDB is due to simultaneous enrichment of both isotopes in the calcite. This correlation indicates that kinetic fractionation occurs between parent drip water and depositing calcite, likely caused by the variations of cave air PCO2 and drip rate influenced by seasonal cave ventilation. Kinetic fractionation amplifies the equilibrium fractionation value of calcite δ18O (by ∼1.5‰) and δ13C (by ∼1.7‰), which quantitatively reflects surface conditions during the cave ventilation season. These results indicate that the cave monitoring of growth rate and δ18O and δ13C of modern calcite precipitation are necessary in order to use a speleothem to reconstruct palaeoenvironment.

  16. Economic viability and critical influencing factors assessment of black water and grey water source-separation sanitation system.

    PubMed

    Thibodeau, C; Monette, F; Glaus, M; Laflamme, C B

    2011-01-01

    The black water and grey water source-separation sanitation system aims at efficient use of energy (biogas), water and nutrients but currently lacks evidence of economic viability to be considered a credible alternative to the conventional system. This study intends to demonstrate economic viability, identify main cost contributors and assess critical influencing factors. A technico-economic model was built based on a new neighbourhood in a Canadian context. Three implementation scales of source-separation system are defined: 500, 5,000 and 50,000 inhabitants. The results show that the source-separation system is 33% to 118% more costly than the conventional system, with the larger cost differential obtained by lower source-separation system implementation scales. A sensitivity analysis demonstrates that vacuum toilet flow reduction from 1.0 to 0.25 L/flush decreases source-separation system cost between 23 and 27%. It also shows that high resource costs can be beneficial or unfavourable to the source-separation system depending on whether the vacuum toilet flow is low or normal. Therefore, the future of this configuration of the source-separation system lies mainly in vacuum toilet flow reduction or the introduction of new efficient effluent volume reduction processes (e.g. reverse osmosis).

  17. Isotope production and distribution Programs Fiscal Year (FY) 1995 Financial Statement Audit (ER-FC-96-01)

    SciTech Connect

    1996-02-12

    The charter of the Department of Energy (DOE) Isotope Production and Distribution Program (Isotope Program) covers the production and sale of radioactive and stable isotopes, associated byproducts, surplus materials such as lithium and deuterium, and related isotope services. Services provided include, but are not limited to, irradiation services, target preparation and processing, source encapsulation and other special preparations, analyses, chemical separations, and leasing of stable isotopes for research purposes. Isotope Program products and services are sold worldwide for use in a wide variety of research, development, biomedical, and industrial applications. The Isotope Program reports to the Director of the Office of Nuclear Energy, Science and Technology. The Isotope Program operates under a revolving fund, as established by the Fiscal Year 1990 Energy and Water Appropriations Act (Public Law 101-101). The Fiscal Year 1995 Appropriations Act (Public Law 103-316) modified predecessor acts to allow prices charged for Isotope Program products and services to be based on production costs, market value, the needs of the research community, and other factors. Prices set for small-volume, high-cost isotopes that are needed for research may not achieve full-cost recovery. Isotope Program costs are financed by revenues from the sale of isotopes and associated services and through payments from the isotope support decision unit, which was established in the DOE fiscal year 1995 Energy, Supply, Research, and Development appropriation. The isotope decision unit finances the production and processing of unprofitable isotopes that are vital to the national interest.

  18. Isotopic Clues on Factors Controlling Geochemical Fluxes From Large Watersheds in Eastern Canada

    NASA Astrophysics Data System (ADS)

    Rosa, E.; Helie, J.; Ghaleb, B.; Hillaire-Marcel, C.; Gaillardet, J.

    2008-12-01

    A monitoring and monthly sampling program of the Nelson, Ottawa, St. Lawrence, La Grande and Great Whale rivers was started in September 2007. It provides information on the seasonality and sources of geochemical fluxes into the Hudson Bay and the North Atlantic from watersheds covering more than 2.6 106 km2 of the eastern Canadian boreal domain. Measurements of pH and alkalinity, analyses of major ions, strontium and dissolved silica, 2H and 18O of water, concentrations and isotopic properties of dissolved organic and inorganic carbon (13C) and uranium (234U/238U) were performed. Lithology more than latitudinal climatic gradients controls the river geochemistry. Rivers draining silicate terrains show lower dissolved U concentrations but greater 234U/238U disequilibria than rivers draining carbonates (average of 1.38 vs. 1.23). Groundwater supplies might exert some control on these U- isotope signatures. No clear seasonality is observed in 234U/238U ratios, but U concentrations are correlated to dissolved organic carbon (DOC) concentrations in most rivers. Rivers draining carbonates present higher total dissolved carbon concentrations and higher 13C-contents in dissolved inorganic carbon (DIC), in response to the dissolution of soil carbonates. DOC/DIC ratios above 2.4 are observed in rivers draining silicates; their lower 13C-DIC content directly reflects the organic matter oxidation in soils. Total dissolved solids are one order of magnitude or more greater in rivers draining carbonates, showing the strong difference in chemical weathering rates according to the geological setting. The stability in chemical fluxes and water isotopic compositions in the La Grande River, which hosts hydroelectric reservoirs covering more than 12 000 km2, indicates that it is the most buffered hydrological system among the investigated watersheds. Seasonal fluctuations are observed elsewhere, with maximum geochemical fluxes during the spring snowmelt. 2H-18O content of river water

  19. Dynamic changes of carbon isotope apparent fractionation factor to describe transition to syntrophic acetate oxidation during cellulose and acetate methanization.

    PubMed

    Vavilin, Vasily A; Rytov, Sergey V

    2017-05-01

    To identify predominant metabolic pathway for cellulose methanization new equations that take into account dynamics of 13C are added to the basic model of cellulose methanization. The correct stoichiometry of hydrolysis, acidogenesis, acetogenesis and methanogenesis steps including biomass is considered. Using experimental data by Laukenmann et al. [Identification of methanogenic pathway in anaerobic digesters using stable carbon isotopes. Eng. Life Sci. 2010;10:1-6], who reported about the importance of ace`tate oxidation during mesophilic cellulose methanization, the model confirmed that, at high biomass concentration of acetate oxidizers, the carbon isotope fractionation factor amounts to about 1.085. The same model, suggested firstly for cellulose degradation, was used to describe, secondly, changes in, and in methane and carbon dioxide during mesophylic acetate methanization measured by Grossin-Debattista [Fractionnements isotopiques (13C/12C) engendres par la methanogenese: apports pour la comprehension des processus de biodegradation lors de la digestion anaerobie [doctoral thesis]. 2011. Bordeaux: Universite Bordeaux-1;2011. Available from: http://ori-oai.u-bordeaux1.fr/pdf/2011/GROSSIN-DEBATTISTA_JULIEN_2011.pdf . French].The model showed that under various ammonium concentrations, at dominating acetoclastic methanogenesis, the value decreases over time to a low level (1.016), while at dominating syntrophic acetate oxidation, coupled with hydrogenotrophic methanogenesis, slightly increases, reaching 1.060 at the end of incubation.

  20. Growth factor controls on the distribution and carbon isotope composition of n-alkanes in leaf wax

    NASA Astrophysics Data System (ADS)

    Jia, C.; Xie, S.; Huang, X.

    2012-12-01

    Cuticular wax plays pivotal physiological and ecological roles in the interactions between plants and the environments in which they grow. Plant-derived long-chain alkanes are more resistant to decay than other biochemical polymers. n-Alkane distributions (Carbon Preference Index (CPI) values and Average Chain Length (ACL) values) and carbon isotopic values are used widely in palaeoenvironmental reconstruction. However, there is little information available on how growth stages of the plant might influence the abundance of n-alkanes in the natural environment. In this study, we analyzed n-alkane distributions and carbon isotope data from two tree species (Cinnamomum camphora (L.) Presl. and Liquidambar formosana Hance) collected monthly from 2009 to 2011 in Nanwang Shan, Wuhan, Hubei Province. CPI values for n-alkanes from C. camphora remained stable in autumn and winter but fluctuated dramatically during spring and autumn each year. Positive correlations between CPI values and the relative content of (C27+C29) were observed in both sun and shade leaves of C. camphora from April to July. In L. formosana, CPI values decreased gradually from April to December. A similar trend was observed in all three years suggesting that growth stages rather than temperature or relative humidity affected the CPI values on a seasonal timescale. In the samples of L. formosana ACL values were negatively correlated with CPI values in the growing season (from April to July) and positively correlated with CPI values in the other seasons. The δ13C values of C29 and C31 n-alkanes displayed more negative carbon isotopic values in autumn and winter compared with leaves sampled at the start of the growing season from both trees. The δ13C values of C29 and C31 n-alkanes of L. formosana decreased from April to December. These results demonstrate the importance of elucidating the growing factors that influence the distribution and δ13C values of alkanes in modern leaves prior to using CPI

  1. Factors controlling carbon isotopic composition of land snail shells estimated from lab culturing experiment

    NASA Astrophysics Data System (ADS)

    Zhang, Naizhong; Yamada, Keita; Yoshida, Naohiro

    2014-05-01

    Carbon isotopic composition (δ13C) of land snail shell carbonate is widely applied in reconstructing the C3/C4 vegetation distribution of paleo-environment, which is considered to reflect variations of some environmental parameters [1][2][3]. Land snail shell carbon has three potential sources: diet, atmospheric CO2 and ingested carbonate (limestone) [4]. However, their relative contributions to shell carbonate have not been understood well yet [4][5][6][7][8]. More researches are necessary before we could apply this tool in paleo-environment reconstruction, especially inter-lab culturing experiment. A kind of land snail species, Acusta despecta sieboldiana, was collected at Yokohama, Japan and cultured under suitable environment to lay eggs. The second generations were growing up from eggs to adults around 6-12 months at the temperature of 20°, 25° and 30°, respectively. All of the snails at 25° and 30° and most of those at 20° were fed by cabbage (C3 plant) during their life span while others were fed by corn (C4 plant). To investigate the effect of ingested carbonate, some of them were fed by Ca3(PO4)2 powder while others were fed by CaCO3 powder. δ13C of shells were analyzed by an Isotope Ratio Mass Spectrometry (Thermo Finnigan MAT 253); δ13C of food and snail tissue were measured by a Cavity Ring-Down Spectroscopy (Picarro G1121-i). At the same time, δ13C of eggshell and new born snails were analyzed by a Continuous Flow Isotope Ratio Mass Spectrometry (GasBench II). We confirmed that diet, atmospheric CO2 and ingested limestone could be important sources controlling shell δ13C values. And the temperature could affect shell carbonate δ13C values, too. A simple but credible frame was raised to discuss the mechanism of how each possible source and environmental parameter could affect shell carbonate δ13C values based on previous works [4][6][8] and this study. According to this frame and some reasonable assumptions, we have estimated the

  2. 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.

  3. Informed Source Separation of Atmospheric and Surface Signal Contributions in Shortwave Hyperspectral Imagery using Non-negative Matrix Factorization

    NASA Astrophysics Data System (ADS)

    Wright, L.; Coddington, O.; Pilewskie, P.

    2015-12-01

    Current challenges in Earth remote sensing require improved instrument spectral resolution, spectral coverage, and radiometric accuracy. Hyperspectral instruments, deployed on both aircraft and spacecraft, are a growing class of Earth observing sensors designed to meet these challenges. They collect large amounts of spectral data, allowing thorough characterization of both atmospheric and surface properties. The higher accuracy and increased spectral and spatial resolutions of new imagers require new numerical approaches for processing imagery and separating surface and atmospheric signals. One potential approach is source separation, which allows us to determine the underlying physical causes of observed changes. Improved signal separation will allow hyperspectral instruments to better address key science questions relevant to climate change, including land-use changes, trends in clouds and atmospheric water vapor, and aerosol characteristics. In this work, we investigate a Non-negative Matrix Factorization (NMF) method for the separation of atmospheric and land surface signal sources. NMF offers marked benefits over other commonly employed techniques, including non-negativity, which avoids physically impossible results, and adaptability, which allows the method to be tailored to hyperspectral source separation. We adapt our NMF algorithm to distinguish between contributions from different physically distinct sources by introducing constraints on spectral and spatial variability and by using library spectra to inform separation. We evaluate our NMF algorithm with simulated hyperspectral images as well as hyperspectral imagery from several instruments including, the NASA Airborne Visible/Infrared Imaging Spectrometer (AVIRIS), NASA Hyperspectral Imager for the Coastal Ocean (HICO) and National Ecological Observatory Network (NEON) Imaging Spectrometer.

  4. Summarizing lecture: factors influencing enzymatic H-transfers, analysis of nuclear tunnelling isotope effects and thermodynamic versus specific effects.

    PubMed

    Marcus, R A

    2006-08-29

    In the articles in this Discussion, a wide variety of topics are treated, including reorganization energy, initially introduced for electron transfers ('environmentally assisted tunnelling'), nuclear tunnelling, H/D and 12C/13C kinetic isotope effects (KIEs), the effect of changes of distal and nearby amino acid residues using site-directed mutagenesis, and dynamics versus statistical effects. A coordinate-free form of semi-classical theory is used to examine topics on data such as tunnelling versus 'over-the-barrier' paths and temperature and pressure effects on KIEs. The multidimensional semi-classical theory includes classically allowed and classically forbidden transitions. More generally, we address the question of relating kinetic to thermodynamic factors, as in the electron transfer field, so learning about specific versus thermodynamic effects in enzyme catalysis and KIEs.

  5. Summarizing lecture: factors influencing enzymatic H-transfers, analysis of nuclear tunnelling isotope effects and thermodynamic versus specific effects

    PubMed Central

    Marcus, R.A

    2006-01-01

    In the articles in this Discussion, a wide variety of topics are treated, including reorganization energy, initially introduced for electron transfers (‘environmentally assisted tunnelling’), nuclear tunnelling, H/D and C12/C13 kinetic isotope effects (KIEs), the effect of changes of distal and nearby amino acid residues using site-directed mutagenesis, and dynamics versus statistical effects. A coordinate-free form of semi-classical theory is used to examine topics on data such as tunnelling versus ‘over-the-barrier’ paths and temperature and pressure effects on KIEs. The multidimensional semi-classical theory includes classically allowed and classically forbidden transitions. More generally, we address the question of relating kinetic to thermodynamic factors, as in the electron transfer field, so learning about specific versus thermodynamic effects in enzyme catalysis and KIEs. PMID:16873131

  6. Separation Anxiety Disorder in Childhood as a Risk Factor for Future Mental Illness

    ERIC Educational Resources Information Center

    Lewinsohn, Peter M.; Holm-Denoma, Jill M.; Small, Jason W.; Seeley, John R.; Joiner, Thomas E.

    2008-01-01

    A study to examine the association between childhood separation anxiety disorder (SAD) and the risk of the development of psychopathology during young adulthood was conducted. Results showed that SAD contributed to the risk for the development of internalizing disorders, which are panic and depression, but decreased the risk for externalizing…

  7. Characters and Clues: Factors Affecting Children's Extension of Knowledge through Integration of Separate Episodes

    ERIC Educational Resources Information Center

    Bauer, Patricia J.; King, Jessica E.; Larkina, Marina; Varga, Nicole L.; White, Elizabeth A.

    2012-01-01

    Children build up knowledge about the world and also remember individual episodes. How individual episodes during which children learn new things become integrated with one another to form general knowledge is only beginning to be explored. Integration between separate episodes is called on in educational contexts and in everyday life as a major…

  8. The effects of military-induced separation on family factors and child behavior.

    PubMed

    Kelley, M L

    1994-01-01

    Data from 61 mothers of school-age children were examined before, during, and after military deployment of their husbands. Separations resulted in temporary disruptions in families' reported ability to maintain supportive relationships. Wives of servicemen sent to the Persian Gulf War reported less nurturance and family cohesiveness, and more internalizing and externalizing in children than did those whose husbands' deployment was routine.

  9. 47 CFR 36.3 - Freezing of jurisdictional separations category relationships and/or allocation factors.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Effective July 1, 2001, through June 30, 2017, all local exchange carriers subject to part 36 rules shall... plant categories during the period July 1, 2001, through June 30, 2017, for which it had no separations... for the duration of the freeze. (b) Effective July 1, 2001, through June 30, 2017, local...

  10. 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

  11. Apparatus for extraction and separation of a preferentially photo-dissociated molecular isotope into positive and negative ions by means of an electric field

    NASA Technical Reports Server (NTRS)

    Wilhelm, H. E. (Inventor)

    1978-01-01

    Molecules of one and the same isotope were preferentially photodissociated by a laser and an ultraviolet source, or by multiphoton absorption of laser radiation. The resultant ions were confined with a magnetic field, moved in opposite directions by an electric field, extracted from the photodissociation region by means of screening and accelerating grids, and collected in ducts.

  12. Factors controlling Li concentration and isotopic composition in formation waters and host rocks of Marcellus Shale, Appalachian Basin

    USGS Publications Warehouse

    Phan, Thai T.; Capo, Rosemary C; Stewart, Brian W.; Macpherson, Gwen; Rowan, Elisabeth L.; Hammack, Richard W.

    2015-01-01

    In Greene Co., southwest Pennsylvania, the Upper Devonian sandstone formation waters have δ7Li values of + 14.6 ± 1.2 (2SD, n = 25), and are distinct from Marcellus Shale formation waters which have δ7Li of + 10.0 ± 0.8 (2SD, n = 12). These two formation waters also maintain distinctive 87Sr/86Sr ratios suggesting hydrologic separation between these units. Applying temperature-dependent illitilization model to Marcellus Shale, we found that Li concentration in clay minerals increased with Li concentration in pore fluid during diagenetic illite-smectite transition. Samples from north central PA show a much smaller range in both δ7Li and 87Sr/86Sr than in southwest Pennsylvania. Spatial variations in Li and δ7Li values show that Marcellus formation waters are not homogeneous across the Appalachian Basin. Marcellus formation waters in the northeastern Pennsylvania portion of the basin show a much smaller range in both δ7Li and 87Sr/86Sr, suggesting long term, cross-formational fluid migration in this region. Assessing the impact of potential mixing of fresh water with deep formation water requires establishment of a geochemical and isotopic baseline in the shallow, fresh water aquifers, and site specific characterization of formation water, followed by long-term monitoring, particularly in regions of future shale gas development.

  13. Oxygen isotope composition of water and snow-ice cover of isolated lakes at various stages of separation from the White Sea

    NASA Astrophysics Data System (ADS)

    Lisitzin, A. P.; Vasil'chuk, Yu. K.; Shevchenko, V. P.; Budantseva, N. A.; Krasnova, E. D.; Pantyulin, A. N.; Filippov, A. S.; Chizhova, Ju. N.

    2013-04-01

    This study aimed to analyze the oxygen isotope composition of water, ice, and snow in water bodies isolated from the White Sea and to identify the structural peculiarities of these pools during the winter period. The studies were performed during early spring in Kandalaksha Bay of the White Sea, in Velikaya Salma Strait and in Rugoserskaya Inlet. The studied water bodies differ in their degree of isolation from the sea. In particular, Ermolinskaya Inlet has normal water exchange with the sea; the Lake on Zelenyi Cape represents the first stage of isolation; i. e., it has permanent water exchange with the sea by the tide. Kislo-Sladkoe Lake receives sea water from time to time. Trekhtsvetnoe Lake is totally isolated from the sea and is a typical meromictic lake. Finally, Nizhnee Ershovskoe Lake exhibits some features of a saline water body. The oxygen isotope profile of the water column in Trekhtsvetnoe Lake allows defining three layers; this lake may be called typically meromictic. The oxygen isotope profile of the water column in Kislo-Sladkoe Lake is even from the surface to the bottom. The variability of δ18O is minor in Lake on Zelenyi Cape. A surface layer (0-1 m) exists in Nizhnee Ershovskoe Lake, and the oxygen isotope variability is well pronounced. Deeper, where the freshwater dominates, the values of ?18Îvary insignificantly disregarding the water depth and temperature. This fresh water lake is not affected by the seawater and is not stratified according to the isotope profile. It is found that applying the values of ?18Î and profiles of temperature and salinity may appear as an effective method in defining the water sources feeding the water bodies isolated from the sea environment.

  14. Increased adult hippocampal brain-derived neurotrophic factor and normal levels of neurogenesis in maternal separation rats.

    PubMed

    Greisen, Mia H; Altar, C Anthony; Bolwig, Tom G; Whitehead, Richard; Wörtwein, Gitta

    2005-03-15

    Repeated maternal separation of rat pups during the early postnatal period may affect brain-derived neurotrophic factor (BDNF) or neurons in brain areas that are compromised by chronic stress. In the present study, a highly significant increase in hippocampal BDNF protein concentration was found in adult rats that as neonates had been subjected to 180 min of daily separation compared with handled rats separated for 15 min daily. BDNF protein was unchanged in the frontal cortex and hypothalamus/paraventricular nucleus. Expression of BDNF mRNA in the CA1, CA3, or dentate gyrus of the hippocampus or in the paraventricular hypothalamic nucleus was not affected by maternal separation. All animals displayed similar behavioral patterns in a forced-swim paradigm, which did not affect BDNF protein concentration in the hippocampus or hypothalamus. Repeated administration of bromodeoxyuridine revealed equal numbers of surviving, newly generated granule cells in the dentate gyrus of adult rats from the 15 min or 180 min groups. The age-dependent decline in neurogenesis from 3 months to 7 months of age did not differ between the groups. Insofar as BDNF can stimulate neurogenesis and repair, we propose that the elevated hippocampal protein concentration found in maternally deprived rats might be a compensatory reaction to separation during the neonatal period, maintaining adult neurogenesis at levels equal to those of the handled rats.

  15. Isotopic fractionation factor and hydrogenic potential in 2-hydroxy-1,1,1,5,5,5-hexafluoro-2-penten-4-one

    SciTech Connect

    Kreevoy, M.M.; Ridl, B.A.

    1981-04-02

    The title compound (enol-hexafluoroacetylacetone) has an isotopic fractionation factor of 0.6 +- 0.1. This, and much other information about this compound, can be rationalized if the enolic hydrogen bridges between the two oxygens and is governed by a double minimum potential function with a central maximum of approx. 3000 cm/sup -1/ (8 kcal/mol)(eq 10).

  16. Boron isotopes in deep-sea bamboo corals: pH, vital effects and environmental factors

    NASA Astrophysics Data System (ADS)

    Farmer, J. R.; Hoenisch, B.; Hill, T. M.; LaVigne, M.; Robinson, L. F.

    2011-12-01

    Deep-sea corals are an intriguing archive for reconstructing deep-ocean environmental conditions, in particular with regard to anthropogenic climate change and ocean acidification. However, previous research in deep-sea aragonitic scleractinian corals observed heterogeneity in their geochemical composition that greatly exceeded the magnitude of variability expected from environmental conditions. Here we investigate the boron isotopic composition (δ11B) and B/Ca ratios of the calcitic gorgonian bamboo coral Keratoisis sp. (family Isididae) as potential indicators of seawater-pH at depth. Initial results from a specimen collected alive on Little Joe Seamount, CA (2136m depth) show that the δ11B of surface calcite is within the expected range of aqueous borate-δ11B, based on seawater pH, temperature, pressure and salinity. A radial cross section through an ~5 cm thick internode reveals largely homogeneous δ11B. However, in the centermost 0.5 cm of calcite growth adjacent to the axial core of the coral, a ~2% increase in δ11B corresponds with disequilibrium depletions in δ13C and δ18O, consistent with hypotheses for different growth modes of central calcite perhaps as a result of active calcite deposition along the axial core. Aside from this central region, the geochemical homogeneity and good agreement between coral surface δ11B and seawater borate δ11B suggests that bamboo corals may record deep-ocean carbon chemistry and thus pH. The cosmopolitan distribution of Keratoisis sp. in both living and fossil deep-sea coral communities thus potentially presents the opportunity to reconstruct recent and Holocene deep-water pH at high resolution.

  17. Surgery and parental separation as potential risk factors for abnormal eating attitudes-longitudinal study.

    PubMed

    Bachar, Eytan; Stein, Daniel; Canetti, Laura; Gur, Eitan

    2008-11-01

    Due to the susceptibility of eating disorders (ED) to stressful life events, we wanted to examine longitudinally whether two childhood adversities: (1) surgery and (2) parental separation, will affect abnormal eating attitudes in adolescents. Consecutively for 4 years, the eating attitude test (EAT-26) and the eating disorder inventory-2 (EDI-2) questionnaires were administered to students from grades 7th through 10th and 8th through 11th. Multilevel analysis revealed that parental separation and oral or cosmetic dermatologic surgeries were significantly correlated with EAT-26 and EDI-2 scores throughout the 4 years of the study. Post-hoc interpretation suggests a connection between (A) chirurgic intervention in the oral cavity and problematic eating attitudes, and (B) cosmetic dermatologic surgery and greater awareness to body appearance-a feature which might characterize adolescents who are prone to develop ED.

  18. 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.

  19. Inhibitory properties of separate recombinant Kunitz-type-protease-inhibitor domains from tissue-factor-pathway inhibitor.

    PubMed

    Petersen, L C; Bjørn, S E; Olsen, O H; Nordfang, O; Norris, F; Norris, K

    1996-01-15

    Tissue-factor-pathway inhibitor (TFPI) is a multivalent inhibitor with three tandemly arranged Kunitz- type-protease-inhibitor (KPI) domains. Previous studies [Girard, Y. J., Warren, L. A., Novotny , W. F., Likert, K. M., Brown, S. G., Miletich, J. R & Broze, G. J. (1989) Nature 338, 518-520] by means of site-directed mutagenesis indicated that KPI domain 1 interacts with factor VIIa, that KPI domain 2 interacts with factor Xa, and that KPI domain 3 is apparently without inhibitory function. To elucidate the reaction mechanism of this complex inhibitor, we followed a different approach and studied the inhibitory properties of fragments of TFPI obtained by expression in yeast. Results obtained with TFPI-(1-161)-peptide and separate recombinant TFPI-KPI domains 1, 2 and 3 showed that KPI domain 1 inhibited factor VIIa/tissue factor (Ki = 250 nM), KPI domain 2 inhibited factor Xa (Ki = 90 nM), and that KPI domain 3 was without detectable inhibitory function. Studies with separate KPI domains also showed that KPI domain 2 was mainly responsible for inhibition of trypsin (Ki = 0.1 nM) and chymotrypsin (Ki = 0.75 nM), whereas KPI domain 1 inhibited plasmin (Ki = 26 nM) and cathepsin G (Ki = 200 nM). The structural basis for the interaction between serine proteases and KPI domains is discussed in terms of putative three-dimensional models of the proteins derived by comparative molecular-modelling methods. Studies of factor Xa inhibition by intact TFPI (Ki approximately 0.02 nM) suggested that regions other than the contact area of the KPI domain, interacted strongly with factor Xa. Secondary-site interactions were crucial for TFPI inhibition of factor Xa but was of little or no importance for its inhibition of trypsin.

  20. Microgravity electrophoresis: A study of the factors that affect free-fluid separation

    NASA Technical Reports Server (NTRS)

    1985-01-01

    Electrophoresis experiments have been performed in the microgravity environment of the Space Shuttle. Test particles (fixed human and rabbit erythrocytes) migrated as expected in a static column and test macromolecules (human serum albumin, ovalbumin, hemoglobin A, and Pneumococcus polysaccharide 6B) migrated as expected in a continuous flow apparatus. The concentrations studied exceeded those that can be used in free-fluid separation and purification processes at unit gravity.

  1. MPP1 as a Factor Regulating Phase Separation in Giant Plasma Membrane-Derived Vesicles

    PubMed Central

    Podkalicka, Joanna; Biernatowska, Agnieszka; Majkowski, Michał; Grzybek, Michał; Sikorski, Aleksander F.

    2015-01-01

    The existence of membrane-rafts helps to conceptually understand the spatiotemporal organization of membrane-associated events (signaling, fusion, fission, etc.). However, as rafts themselves are nanoscopic, dynamic, and transient assemblies, they cannot be directly observed in a metabolizing cell by traditional microscopy. The observation of phase separation in giant plasma membrane-derived vesicles from live cells is a powerful tool for studying lateral heterogeneity in eukaryotic cell membranes, specifically in the context of membrane rafts. Microscopic phase separation is detectable by fluorescent labeling, followed by cooling of the membranes below their miscibility phase transition temperature. It remains unclear, however, if this lipid-driven process is tuneable in any way by interactions with proteins. Here, we demonstrate that MPP1, a member of the MAGUK family, can modulate membrane properties such as the fluidity and phase separation capability of giant plasma membrane-derived vesicles. Our data suggest that physicochemical domain properties of the membrane can be modulated, without major changes in lipid composition, through proteins such as MPP1. PMID:25954878

  2. Characters and clues: Factors affecting children’s extension of knowledge through integration of separate episodes

    PubMed Central

    Bauer, Patricia J.; King, Jessica E.; Larkina, Marina; Varga, Nicole L.; White, Elizabeth A.

    2012-01-01

    Children build up knowledge about the world and also remember individual episodes. How individual episodes during which children learn new things become integrated with one another to form general knowledge is only beginning to be explored. Integration between separate episodes is called on in educational contexts and in everyday life as a major means of extending knowledge and organizing information. Bauer and San Souci (2010) provided an initial demonstration that 6-year-olds extend their knowledge by integrating between separate but related episodes; the episodes shared a high level of surface similarity. Experiments 1A and 1B of the current research were tests of integration under low and high levels of surface similarity, respectively. In Experiment 1A, when surface similarity of the episodes was low, 6-year-olds integrated between passages of text, yet their performance was not as robust as observed previously. In Experiment 1B, when surface similarity of the episodes was high, a replication of Bauer and San Souci’s results was observed. In Experiment 2, we tested whether a “hint” to consult the information learned in the passages improved performance even when surface level similarity was low. The hint had a strong facilitating effect. Possible mechanisms of integration between separate yet related episodes are discussed. PMID:22153911

  3. 47 CFR 36.3 - Freezing of jurisdictional separations category relationships and/or allocation factors.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... July 1, 2001, of such intent to be subject to the provisions of § 36.3(b). (c) Effective July 1, 2001... calculate new, composite factors and, if applicable, category relationships based on a weighted average of... the composite allocation factors and, if applicable, the composite category percentage...

  4. Controlling factors of rainwater and water vapor isotopes at Bangalore, India: Constraints from observations in 2013 Indian monsoon

    NASA Astrophysics Data System (ADS)

    Rahul, P.; Ghosh, Prosenjit; Bhattacharya, S. K.; Yoshimura, Kei

    2016-12-01

    Isotopic ratios of rainwaters are believed to decrease with the amount of rainfall. However, analyses of the isotopic composition of rainwater and water vapor samples collected from Bangalore during the monsoon period of 2013 fail to show any simple relationship with the local meteorological parameters whereas show good correlation with the regional integrated convective activity. The correlation is particularly high when the averaging is done over the preceding 8 to 15 days, showing the influence of mixing or residence time scale of atmospheric moisture. This observation emphasizes the role of regional atmospheric circulation driving the isotopic values. A comparison between observed isotope ratios in water vapor and rainwater with Isotope-enabled Global Spectral Model shows discrepancies between the two. The observed values are relatively enriched, indicating a systematic bias in the model values. The higher observed values suggest underestimation of the evaporation in the model, which we estimate to be about 28 ± 15% on average. Simultaneous analyses of rainwater and water vapor isotopic composition again show definitive presence of raindrop evaporation (31 ± 14%). We also documented a distinct pattern of isotopic variation in six samples collected at Bangalore due to mixing of vapor from a cyclonic system in close proximity that originated from the Bay of Bengal. It seems that large-scale isotopic depletion occurs during cyclones caused by Rayleigh fractionation due to massive rainout. These results demonstrate the power of rainwater and water vapor isotope monitoring to elucidate the genesis and dynamics of water recycling within synoptic-scale monsoon systems.

  5. On-line method of determining utilization factor in Hg-196 photochemical separation process

    DOEpatents

    Grossman, Mark W.; Moskowitz, Philip E.

    1992-01-01

    The present invention is directed to a method for determining the utilization factor [U] in a photochemical mercury enrichment process (.sup.196 Hg) by measuring relative .sup.196 Hg densities using absorption spectroscopy.

  6. Towards A Modern Calibration Of The 238U/235U Paleoredox Proxy: Apparent Uranium Isotope Fractionation Factor During U(VI)-U(IV) Reduction In The Black Sea

    NASA Astrophysics Data System (ADS)

    Rolison, J. M.; Stirling, C. H.; Middag, R.; Rijkenberg, M. J. A.; De Baar, H. J. W.

    2015-12-01

    The isotopic compositions of redox-sensitive metals, including uranium (U), in marine sediments have recently emerged as powerful diagnostic tracers of the redox state of the ancient ocean-atmosphere system. Interpretation of sedimentary isotopic information requires a thorough understating of the environmental controls on isotopic fractionation in modern anoxic environments before being applied to the paleo-record. In this study, the relationship between ocean anoxia and the isotopic fractionation of U was investigated in the water column and sediments of the Black Sea. The Black Sea is the world's largest anoxic basin and significant removal of U from the water column and high U accumulation rates in modern underlying sediments have been documented. Removal of U from the water column occurs during the redox transition of soluble U(VI) to relatively insoluble U(IV). The primary results of this study are two-fold. First, significant 238U/235U fractionation was observed in the water column of the Black Sea, suggesting the reduction of U induces 238U/235U fractionation with the preferential removal of 238U from the aqueous phase. Second, the 238U/235U of underlying sediments is related to the water column through the isotope fractionation factor of the reduction reaction but is influenced by mass transport processes. These results provide important constraints on the use of 238U/235U as a proxy of the redox state of ancient oceans.

  7. Equilibrium Iron Isotope Fractionation Factors of Minerals: Reevaluation from the Data of Nuclear Inelastic Resonant X-ray Scattering and Mossbauer Spectroscopy

    SciTech Connect

    Polyakov, Dr. V. B.; Clayton, R. N.; Horita, Juske; Mineev, S. D.

    2007-01-01

    We have critically reevaluated equilibrium iron isotope fractionation factors for oxide and sulfide minerals using recently acquired data obtained by Moessbauer spectroscopy and inelastic nuclear resonant X-ray scattering (INRXS) synchrotron radiation. Good agreement was observed in the iron {beta}-factors of metallic iron ({alpha}-Fe) and hematite calculated using both Moessbauer- and INRXS-derived data, which supports the validity and reliability of the calculations. Based on this excellent agreement, we suggest the use of the present data on the iron {beta}-factors of hematite as a reference. The previous Moessbauer-derived iron {beta}-factor for magnetite has been modified significantly based on the Fe-sublattice density of states obtained from the INRXS experiments. This resolves the disagreement between naturally observed iron isotope fractionation factors for mineral pairs involving magnetite and those obtained from the calculated {beta}-factors. The correctness of iron {beta}-factor for pyrite has been corroborated by the good agreement with experimental data of sulfur isotope geothermometers of pyrite-galena and pyrite-sphalerite. A good correlation between the potential energy of the cation site, the oxidation state of iron and the iron {beta}-factor value has been established. Specifically, ferric compounds, which have a higher potential energy of iron than ferrous compounds, have higher {beta}-factors. A similar dependence of b-factors on the oxidation state and potential energy could be extended to other transition metals. Extremely low values of INRXS-derived iron {beta}-factors for troilite and Fe{sub 3}S significantly widen the range of iron b-factors for covalently bonded compounds.

  8. Behavioral effects of peripheral corticotropin-releasing factor during maternal separation may be mediated by proinflammatory activity

    PubMed Central

    Hennessy, Michael B.; Fitch, Christopher; Jacobs, Sarah; Deak, Terrence; Schiml, Patricia A.

    2013-01-01

    Summary When guinea pig pups are separated from their mothers in a novel environment, an initial period of active behavior (vocalizing, locomotor activity) wanes after an hour or so and is replaced by a second, passive stage characterized by a crouched stance, closed eyes, and extensive piloerection. If pups are given a peripheral injection of 7–14 μg of corticotropin-releasing factor (CRF) prior to testing, the passive behaviors occur immediately upon separation. We found that intracerebroventricular infusion of 1–10 μg of CRF did not increase passive behavior relative to vehicle infusion, but that peripheral injection of the anti-inflammatory cytokine, Interleukin-10, attenuated the passive behavior induced by peripheral CRF injection. These results together with previous findings suggest that peripheral CRF administration affects behavior of separated guinea pig pups through a mechanism that involves peripheral proinflammatory activity. The possible role of endogenous peripheral CRF in the behavioral response of untreated pups during maternal separation is considered. PMID:21255937

  9. Comparing compound-specific and bulk stable nitrogen isotope trophic discrimination factors across multiple freshwater fish species and diets

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The use of nitrogen stable isotopes for estimation of animal trophic position has become an indispensable approach in food web ecology. Compound-specific isotope analysis of amino acids is a new approach for estimating trophic position that may overcome key issues associated with nitrogen stable iso...

  10. Factor analysis as a tool for spectral line component separation 21cm emission in the direction of L1780

    NASA Technical Reports Server (NTRS)

    Toth, L. V.; Mattila, K.; Haikala, L.; Balazs, L. G.

    1992-01-01

    The spectra of the 21cm HI radiation from the direction of L1780, a small high-galactic latitude dark/molecular cloud, were analyzed by multivariate methods. Factor analysis was performed on HI (21cm) spectra in order to separate the different components responsible for the spectral features. The rotated, orthogonal factors explain the spectra as a sum of radiation from the background (an extended HI emission layer), and from the L1780 dark cloud. The coefficients of the cloud-indicator factors were used to locate the HI 'halo' of the molecular cloud. Our statistically derived 'background' and 'cloud' spectral profiles, as well as the spatial distribution of the HI halo emission distribution were compared to the results of a previous study which used conventional methods analyzing nearly the same data set.

  11. Separable projection integrals for higher-order correlators of the cosmic microwave sky: Acceleration by factors exceeding 100

    NASA Astrophysics Data System (ADS)

    Briggs, J. P.; Pennycook, S. J.; Fergusson, J. R.; Jäykkä, J.; Shellard, E. P. S.

    2016-04-01

    We present a case study describing efforts to optimise and modernise ;Modal;, the simulation and analysis pipeline used by the Planck satellite experiment for constraining general non-Gaussian models of the early universe via the bispectrum (or three-point correlator) of the cosmic microwave background radiation. We focus on one particular element of the code: the projection of bispectra from the end of inflation to the spherical shell at decoupling, which defines the CMB we observe today. This code involves a three-dimensional inner product between two functions, one of which requires an integral, on a non-rectangular domain containing a sparse grid. We show that by employing separable methods this calculation can be reduced to a one-dimensional summation plus two integrations, reducing the overall dimensionality from four to three. The introduction of separable functions also solves the issue of the non-rectangular sparse grid. This separable method can become unstable in certain scenarios and so the slower non-separable integral must be calculated instead. We present a discussion of the optimisation of both approaches. We demonstrate significant speed-ups of ≈100×, arising from a combination of algorithmic improvements and architecture-aware optimisations targeted at improving thread and vectorisation behaviour. The resulting MPI/OpenMP hybrid code is capable of executing on clusters containing processors and/or coprocessors, with strong-scaling efficiency of 98.6% on up to 16 nodes. We find that a single coprocessor outperforms two processor sockets by a factor of 1.3× and that running the same code across a combination of both microarchitectures improves performance-per-node by a factor of 3.38×. By making bispectrum calculations competitive with those for the power spectrum (or two-point correlator) we are now able to consider joint analysis for cosmological science exploitation of new data.

  12. Separable projection integrals for higher-order correlators of the cosmic microwave sky: Acceleration by factors exceeding 100

    SciTech Connect

    Briggs, J.P.; Pennycook, S.J.; Fergusson, J.R.; Jäykkä, J.; Shellard, E.P.S.

    2016-04-01

    We present a case study describing efforts to optimise and modernise “Modal”, the simulation and analysis pipeline used by the Planck satellite experiment for constraining general non-Gaussian models of the early universe via the bispectrum (or three-point correlator) of the cosmic microwave background radiation. We focus on one particular element of the code: the projection of bispectra from the end of inflation to the spherical shell at decoupling, which defines the CMB we observe today. This code involves a three-dimensional inner product between two functions, one of which requires an integral, on a non-rectangular domain containing a sparse grid. We show that by employing separable methods this calculation can be reduced to a one-dimensional summation plus two integrations, reducing the overall dimensionality from four to three. The introduction of separable functions also solves the issue of the non-rectangular sparse grid. This separable method can become unstable in certain scenarios and so the slower non-separable integral must be calculated instead. We present a discussion of the optimisation of both approaches. We demonstrate significant speed-ups of ≈100×, arising from a combination of algorithmic improvements and architecture-aware optimisations targeted at improving thread and vectorisation behaviour. The resulting MPI/OpenMP hybrid code is capable of executing on clusters containing processors and/or coprocessors, with strong-scaling efficiency of 98.6% on up to 16 nodes. We find that a single coprocessor outperforms two processor sockets by a factor of 1.3× and that running the same code across a combination of both microarchitectures improves performance-per-node by a factor of 3.38×. By making bispectrum calculations competitive with those for the power spectrum (or two-point correlator) we are now able to consider joint analysis for cosmological science exploitation of new data.

  13. Factors that contribute to the improvement in maternal parenting after separation from a violent husband or partner.

    PubMed

    Fujiwara, Takeo; Okuyama, Makiko; Izumi, Mayuko

    2012-01-01

    The authors test the hypothesis that separation from a violent husband or partner improves maternal parenting in Japan and examine how childhood abuse history (CAH), experience of domestic violence (DV), mental health problems, husband or partner's child maltreatment, and other demographic factors affect maternal parenting after such separation. A self-administered questionnaire survey is conducted for mothers (n = 304) and their children (n = 498) staying in 83 mother-child homes in Japan to assess the mothers' CAH, DV experiences, current mental health problems, and exposure to a husband or partner's child maltreatment. The authors also assess maternal poor parenting (physical and psychological abuse, neglect, no playing, and no praise) before and after admission into the mother-child homes. The total poor parenting score (specifically for neglect, no playing, and no praise) significantly reduces after separation from a violent husband or partner (p = .001, paired t test). However, scores for psychological abuse significantly increase after admission (p < .001, paired t test). CAH, DV, and mental health problems are not associated with a reduced total poor parenting score after admission. Husband or partner's child maltreatment is independently significantly associated with a reduced maternal poor parenting score: A 10% increase in such maltreatment is associated with a 5% reduction in the poor parenting score after separation. Marital status also contributes to the score reduction: The reduction is less in married or divorced mothers than in those who did not marry the partner. Mother-child homes might be useful for improving maternal parenting. Further study is needed to elucidate the mechanism of the impact of separation from a violent husband or partner on maternal parenting.

  14. Carbon isotopes of plant biomarkers record past changes in the carbon cycle, but separating signal from noise is key to reducing uncertainties

    NASA Astrophysics Data System (ADS)

    Diefendorf, A. F.; Freeman, K. H.; Wing, S. L.; Currano, E. D.

    2014-12-01

    The carbon isotopic composition of plant biomarkers (δ13C) can provide unique insights into the past carbon cycle perturbations and associated climate change, however local records are influenced by ecological processes, local climate, as well as changes in the carbon isotope composition of the atmosphere. To examine the sources and amounts of geographic variation, we focused on long-term changes in the carbon cycle. We combined modern calibrations, δ13C of biomarkers in sediment, and Monte Carlo analyses to measure and predict the fractionation of carbon isotopes by plants (Δleaf) and to estimate error. We used data from multiple sites of different ages, in the western U.S. For each age and location, Δleaf was calculated from the δ13C of plant biomarkers and atmospheric δ13C values inferred from marine carbonates. Δleaf values calculated from n-alkanes and triterpenoids (angiosperm biomarkers) were found to be the same at each site. Δleaf calculated from diterpenoids (conifer biomarkers) was 2‰ lower. This is consistent with differences in Δleaf between living angiosperms and conifers. Predicted Δleaf values, from modern calibrations and paleoclimate data, were consistently offset (0.7‰) from measured values indicating that modern calibrations are useful for reconciling past changes in plant fractionation and that vegetation and precipitation, like modern plants, were the key controls on Δleaf in ancient vegetation. However, uncertainties in the measured and predicted Δleaf values were very large (>2‰, 1σ). A one-at-a-time sensitivity analysis indicates that 'biological noise' in modern calibrations explains most of this uncertainty. If the full extent of this biological noise were transferred to sediments, then extracting signal from noise would be challenging. However, we speculate that the process of deposition homogenizes variability at the leaf and tree level thereby reducing 'biological noise' observed in modern calibrations.

  15. Factors determining the average body size of geographically separated Arctodiaptomus salinus (Daday, 1885) populations

    PubMed Central

    Anufriieva, Elena V.; Shadrin, Nickolai V.

    2014-01-01

    Arctodiaptomus salinus inhabits water bodies across Eurasia and North Africa. Based on our own data and that from the literature, we analyzed the influences of several factors on the intra- and inter-population variability of this species. A strong negative linear correlation between temperature and average body size in the Crimean and African populations was found, in which the parameters might be influenced by salinity. Meanwhile, asignificant negative correlation between female body size and the altitude of habitats was found by comparing body size in populations from different regions. Individuals from environments with highly varying abiotic parameters, e.g. temporary reservoirs, had a larger body size than individuals from permanent water bodies. The changes in average body mass in populations were at 11.4 times, whereas, those in individual metabolic activities were at 6.2 times. Moreover, two size groups of A. salinus in the Crimean and the Siberian lakes were observed. The ratio of female length to male length fluctuatedbetween 1.02 and 1.30. The average size of A. salinus in populations and its variations were determined by both genetic and environmental factors. However, the paritiesof these factors were unequal in either spatial or temporal scales. PMID:24668656

  16. Factors affecting temperature rise on the external root surface during ultrasonic retrieval of intracanal separated files.

    PubMed

    Madarati, Ahmad A; Qualtrough, Alison J; Watts, David C

    2008-09-01

    Temperature rise (TR) on the external root surface during ultrasonic removal of separated files (SFs) from 50 lower incisors roots of 10-mm length was investigated. CPR ultrasonic tips (Obtura-Spartan, Fenton, MO) were used dry to retrieve F2 ProTaper (Dentsply, Surrey, UK) segments fractured 2.5 mm from the coronal access in five groups: CPR2, CPR5, and CPR6 at power setting 1 and CPR5 at power settings 2.5 and 5. Temperature changes were inspected at 30-second intervals up to 120 seconds at three different sites: two at mesiodistal and buccolingual surfaces adjacent to the most coronal aspect of the SF and the third adjacent to the most apical aspect. Overall, the highest mean TR was at the buccolingual root surface followed by that at the mesiodistal and the more apical site surfaces. At power setting 1, CPR6 produced a significantly lower TR than CPR5, and both can be used for 120 and 60 seconds, respectively. Power setting 5 is not recommended for the removal of SF because this induces a hazardous TR.

  17. Environmental site description for a Uranium Atomic Vapor Laser Isotope Separation (U-AVLIS) production plant at the Paducah Gaseous Diffusion Plant site

    SciTech Connect

    Marmer, G.J.; Dunn, C.P.; Moeller, K.L.; Pfingston, J.M.; Policastro, A.J.; Yuen, C.R.; Cleland, J.H.

    1991-09-01

    Uranium enrichment in the United States has utilized a diffusion process to preferentially enrich the U-235 isotope in the uranium product. The U-AVLIS process is based on electrostatic extraction of photoionized U-235 atoms from an atomic vapor stream created by electron-beam vaporization of uranium metal alloy. The U-235 atoms are ionized when precisely tuned laser light -- of appropriate power, spectral, and temporal characteristics -- illuminates the uranium vapor and selectively photoionizes the U-235 isotope. A programmatic document for use in screening DOE site to locate a U-AVLIS production plant was developed and implemented in two parts. The first part consisted of a series of screening analyses, based on exclusionary and other criteria, that identified a reasonable number of candidate sites. These sites were subjected to a more rigorous and detailed comparative analysis for the purpose of developing a short list of reasonable alternative sites for later environmental examination. This environmental site description (ESD) provides a detailed description of the PGDP site and vicinity suitable for use in an environmental impact statement (EIS). The report is based on existing literature, data collected at the site, and information collected by Argonne National Laboratory (ANL) staff during a site visit. 65 refs., 15 tabs.

  18. Xeroderma Pigmentosum Group A Protein Loads as a Separate Factor onto DNA Lesions

    PubMed Central

    Rademakers, Suzanne; Volker, Marcel; Hoogstraten, Deborah; Nigg, Alex L.; Moné, Martijn J.; van Zeeland, Albert A.; Hoeijmakers, Jan H. J.; Houtsmuller, Adriaan B.; Vermeulen, Wim

    2003-01-01

    Nucleotide excision repair (NER) is the main DNA repair pathway in mammals for removal of UV-induced lesions. NER involves the concerted action of more than 25 polypeptides in a coordinated fashion. The xeroderma pigmentosum group A protein (XPA) has been suggested to function as a central organizer and damage verifier in NER. How XPA reaches DNA lesions and how the protein is distributed in time and space in living cells are unknown. Here we studied XPA in vivo by using a cell line stably expressing physiological levels of functional XPA fused to green fluorescent protein and by applying quantitative fluorescence microscopy. The majority of XPA moves rapidly through the nucleoplasm with a diffusion rate different from those of other NER factors tested, arguing against a preassembled XPA-containing NER complex. DNA damage induced a transient (∼5-min) immobilization of maximally 30% of XPA. Immobilization depends on XPC, indicating that XPA is not the initial lesion recognition protein in vivo. Moreover, loading of replication protein A on NER lesions was not dependent on XPA. Thus, XPA participates in NER by incorporation of free diffusing molecules in XPC-dependent NER-DNA complexes. This study supports a model for a rapid consecutive assembly of free NER factors, and a relatively slow simultaneous disassembly, after repair. PMID:12897146

  19. 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.

  20. Factors influencing the stable carbon isotopic signature of methane from combustion and biomass burning

    NASA Astrophysics Data System (ADS)

    Chanton, Jeffrey P.; Rutkowski, Christine M.; Schwartz, Candace C.; Ward, Darold E.; Boring, Lindsay

    2000-01-01

    Factors controlling the δ13C of methane released by combustion include the combustion efficiency of the fire and the δ13C of the fuel. Smoldering fires produced 13C-depleted methane relative to hot, flaming fires in controlled forest and grassland burns and within a wood stove. Pine forest burns in the southeastern United States produced methane which ranged from -21 to -30‰, while African grassland burns varied from -17 to -26‰, depending upon combustion phase. African woodland burns produced methane at -30‰. In forest burns in the southeastern United States, the δ13C of methane released with smoldering was significantly 13C depleted relative to methane released under hot flaming conditions. Methane released with smoldering was depleted by 2-3‰ relative to the fuel δ13C, but this difference was not significant. The δ13C of methane produced in a variety of wood stove conditions varied from -9 to -25‰ and also depended upon combustion efficiency. Similar results were found for methane produced by gasoline automobile engines, where the δ13C of methane varied from -9 to -22‰. For combustion occurring within the confining chamber of a wood stove or engine the δ13C of methane was clearly 13C enriched relative to the δ13C of the fuel, possibly because of preferential combustion of 12CH4 in the gas phase. Significant quantities of ethylene (up to 25 to 50% of methane concentrations) were produced in southeastern U.S. forest fires, which may have consequences for physiological and reproductive responses of plants in the ecosystem. Methane production in these fires varied from 0.2 to 8.5% of the carbon dioxide production.

  1. Scattering from phase-separated vesicles. I. An analytical form factor for multiple static domains

    SciTech Connect

    Heberle, Frederick A.; Anghel, Vinicius N. P.; Katsaras, John

    2015-08-18

    This is the first in a series of studies considering elastic scattering from laterally heterogeneous lipid vesicles containing multiple domains. Unique among biophysical tools, small-angle neutron scattering can in principle give detailed information about the size, shape and spatial arrangement of domains. A general theory for scattering from laterally heterogeneous vesicles is presented, and the analytical form factor for static domains with arbitrary spatial configuration is derived, including a simplification for uniformly sized round domains. The validity of the model, including series truncation effects, is assessed by comparison with simulated data obtained from a Monte Carlo method. Several aspects of the analytical solution for scattering intensity are discussed in the context of small-angle neutron scattering data, including the effect of varying domain size and number, as well as solvent contrast. Finally, the analysis indicates that effects of domain formation are most pronounced when the vesicle's average scattering length density matches that of the surrounding solvent.

  2. Isotopic Biogeochemistry

    NASA Technical Reports Server (NTRS)

    Hayes, J. M.

    1985-01-01

    An overview is provided of the biogeochemical research. The funding, productivity, personnel and facilities are reviewed. Some of the technical areas covered are: carbon isotopic records; isotopic studies of banded iron formations; isotope effects in microbial systems; studies of organic compounds in ancient sediments; and development in isotopic geochemistry and analysis.

  3. 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.

  4. Separation factor in the photoassisted catalytic decomposition of tritiated water by Pt/TiO/sub 2/

    SciTech Connect

    Watanabe, K.; Ichimura, K.; Inoue, N.; Matsuura, I.

    1986-02-27

    The hydrogen separation factor was measured for the H/sub 2/O-HTO system in a photoassisted catalytic decomposition along with that for the H/sub 2/O-D/sub 2/O system. It was 15.4 +/- 0.2 for H/sub 2/O-HTO at the initial stage of the reaction. For H/sub 2/O-D/sub 2/O, it was 5.1 +/- 0.05 over a wide mixing ratio. These values are equivalent with those from electrolysis, indicating that the photoassisted decomposition proceeds with the same mechanism as the electrolysis. These results also confirmed that the catalytic process is the rate-determining step. The separation factors, however, decreased with reaction time to 6.2 +/- 0.00 (H/sub 2/O-HTO), 3.6 +/- 0.05 (H/sub 2/O-HDO), and 3.05 +/- 0.05 (D/sub 2/O-HDO) due to the gas-liquid equilibration reaction. 18 references, 2 figures.

  5. Refined separation of combined Fe–Hf from rock matrices for isotope analyses using AG-MP-1M and Ln-Spec chromatographic extraction resins

    PubMed Central

    Cheng, Ting; Nebel, Oliver; Sossi, Paolo A.; Chen, Fukun

    2014-01-01

    A combined procedure for separating Fe and Hf from a single rock digestion is presented. In a two-stage chromatographic extraction process, a purified Fe fraction is first quantitatively separated from the rock matrix using AG-MP-1M resin in HCl. Hafnium is subsequently isolated using a modified version of a commonly applied method using Eichrom LN-Spec resin. Our combined method includes:•Purification of Fe from the rock matrix using HCl, ready for mass spectrometric analysis.•Direct loading of the matrix onto the resin that is used for Hf purification.•Collection of a Fe-free Hf fraction. PMID:26150946

  6. Scattering from phase-separated vesicles. I. An analytical form factor for multiple static domains

    DOE PAGES

    Heberle, Frederick A.; Anghel, Vinicius N. P.; Katsaras, John

    2015-08-18

    This is the first in a series of studies considering elastic scattering from laterally heterogeneous lipid vesicles containing multiple domains. Unique among biophysical tools, small-angle neutron scattering can in principle give detailed information about the size, shape and spatial arrangement of domains. A general theory for scattering from laterally heterogeneous vesicles is presented, and the analytical form factor for static domains with arbitrary spatial configuration is derived, including a simplification for uniformly sized round domains. The validity of the model, including series truncation effects, is assessed by comparison with simulated data obtained from a Monte Carlo method. Several aspects ofmore » the analytical solution for scattering intensity are discussed in the context of small-angle neutron scattering data, including the effect of varying domain size and number, as well as solvent contrast. Finally, the analysis indicates that effects of domain formation are most pronounced when the vesicle's average scattering length density matches that of the surrounding solvent.« less

  7. Using Separable Nonnegative Matrix Factorization Techniques for the Analysis of Time-Resolved Raman Spectra.

    PubMed

    Luce, Robert; Hildebrandt, Peter; Kuhlmann, Uwe; Liesen, Jörg

    2016-09-01

    The key challenge of time-resolved Raman spectroscopy is the identification of the constituent species and the analysis of the kinetics of the underlying reaction network. In this work we present an integral approach that allows for determining both the component spectra and the rate constants simultaneously from a series of vibrational spectra. It is based on an algorithm for nonnegative matrix factorization that is applied to the experimental data set following a few pre-processing steps. As a prerequisite for physically unambiguous solutions, each component spectrum must include one vibrational band that does not significantly interfere with the vibrational bands of other species. The approach is applied to synthetic "experimental" spectra derived from model systems comprising a set of species with component spectra differing with respect to their degree of spectral interferences and signal-to-noise ratios. In each case, the species involved are connected via monomolecular reaction pathways. The potential and limitations of the approach for recovering the respective rate constants and component spectra are discussed.

  8. Battery separators.

    PubMed

    Arora, Pankaj; Zhang, Zhengming John

    2004-10-01

    The ideal battery separator would be infinitesimally thin, offer no resistance to ionic transport in electrolytes, provide infinite resistance to electronic conductivity for isolation of electrodes, be highly tortuous to prevent dendritic growths, and be inert to chemical reactions. Unfortunately, in the real world the ideal case does not exist. Real world separators are electronically insulating membranes whose ionic resistivity is brought to the desired range by manipulating the membranes thickness and porosity. It is clear that no single separator satisfies all the needs of battery designers, and compromises have to be made. It is ultimately the application that decides which separator is most suitable. We hope that this paper will be a useful tool and will help the battery manufacturers in selecting the most appropriate separators for their batteries and respective applications. The information provided is purely technical and does not include other very important parameters, such as cost of production, availability, and long-term stability. There has been a continued demand for thinner battery separators to increase battery power and capacity. This has been especially true for lithiumion batteries used in portable electronics. However, it is very important to ensure the continued safety of batteries, and this is where the role of the separator is greatest. Thus, it is essential to optimize all the components of battery to improve the performance while maintaining the safety of these cells. Separator manufacturers should work along with the battery manufacturers to create the next generation of batteries with increased reliability and performance, but always keeping safety in mind. This paper has attempted to present a comprehensive review of literature on separators used in various batteries. It is evident that a wide variety of separators are available and that they are critical components in batteries. In many cases, the separator is one of the major factors

  9. Stable Isotope Systematics of Martian Perchlorate

    NASA Astrophysics Data System (ADS)

    Martin, P.; Farley, K. A.; Archer, D., Jr.; Atreya, S. K.; Conrad, P. G.; Eigenbrode, J. L.; Fairen, A.; Franz, H. B.; Freissinet, C.; Glavin, D. P.; Mahaffy, P. R.; Malespin, C.; Ming, D. W.; Navarro-Gonzalez, R.; Sutter, B.

    2015-12-01

    Chlorine isotopic compositions in HCl released during evolved gas analysis (EGA) runs have been detected by the Sample Analysis at Mars (SAM) instrument on the Curiosity rover ranging from approximately -9‰ to -50‰ δ37Cl, with two spatially and isotopically separated groups of samples averaging -15‰ and -45‰. These extremely low values are the first such detection of any known natural material; common terrestrial values very rarely exceed ±5‰, and the most extreme isotopic signature yet detected elsewhere in the solar system are values of around +24‰ on the Moon. The only other known location in the solar system with large negative chlorine isotopes is the Atacama Desert, where perchlorate with -14‰ δ37Cl has been detected. The Atacama perchlorate has unusual Δ17O signatures associated with it, indicating a formation mechanism involving O3, which suggests an atmospheric origin of the perchlorate and associated large isotopic anomalies. Identification of non-zero positive Δ17O signatures in the O2 released during EGA runs would allow definitive evidence for a similar process having occurred on Mars. Perchlorate is thought to be the most likely source of HCl in EGA runs due to the simultaneous onset of O2 release. If perchlorate is indeed the HCl source, atmospheric chemistry could be responsible for the observed isotopic anomalies, with variable extents of perchlorate production producing the isotopic variability. However, chloride salts have also been observed to release HCl upon heating; if the timing of O2 release is merely coincidental, observed HCl could be coming from chlorides. At thermodynamic equilibrium, the fractionation factor of perchlorate reduction is 0.93, meaning that differing amounts of post-deposition reduction of isotopically normal perchlorate to chloride could account for the highly variable Cl isotopes. Additionally, post-deposition reduction could account for the difference between the two Cl isotopic groups if perchlorate

  10. Compound-specific stable isotope records of precipitation isotopes and paleotopographic evolution: Patterns of Cenozoic change in the Western U.S.

    NASA Astrophysics Data System (ADS)

    Hren, M. T.

    2014-12-01

    The topography of an orogen reflects the complex interplay between processes that occur at depth in the crust and processes such as erosion and weathering that shape the surface landscape. Reconstructions of paleotopography are critical for evaluating geodynamic models and separating effects of climatic and tectonic change in terrestrial records. Stable isotope paleoaltimetry has proved to be an important tool for understanding changes in topography through time, however this approach is complicated by factors such as mixing of moisture sources, uncertainty over how uplift impacts air mass transport and resultant isotope hydrology, and debate over what some proxies actually record. Hydrogen isotopes of organic molecules provide a means of reconstructing isotopes of ambient water, but these data are also impacted by factors that affect biological processes and stomatal regulation. Despite the myriad factors that can impact isotope fractionation in plant waxes, a growing body of data show these molecules to be an important record of precipitation isotopes when coupled with data that relates to ecosystem type. This study will examine the distribution of hydrogen isotopes of higher plant waxes across the western U.S. at key intervals of the Cenozoic to provide a snapshot of long-wavelength changes to topography and moisture sources from the Eocene to recent. These data demonstrate the utility of biomarker isotopes as a paleohydrologic/paleotopographic proxy and point to long-standing high topography over much of western U.S. throughout the Cenozoic.

  11. Highly tritiated water processing by isotopic exchange

    SciTech Connect

    Shu, W.M.; Willms, R.S.; Glugla, M.; Cristescu, I.; Michling, R.; Demange, D.

    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 applied 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.

  12. Unusual isotopic composition of C-CO2 from sterilized soil microcosms: a new way to separate intracellular from extracellular respiratory metabolisms.

    NASA Astrophysics Data System (ADS)

    Kéraval, Benoit; Alvarez, Gaël; Lehours, Anne Catherine; Amblard, Christian; Fontaine, Sebastien

    2015-04-01

    intact cells were observed by microscopy. These "ghost" cells were completely destroyed by the irradiation-autoclaving combination releasing large amount of soluble C. The soil respiration (O2 consumption and CO2 production) was reduced by irradiation and autoclaving but not stopped, suggesting the presence of an EXOMET. The delta 13C of CO2 released in the irradiated-autoclaved soil was strongly depleted (-70‰) indicating that this extracellular metabolism induced a substantial isotopic fractionation. Our findings suggest that two main oxidative metabolisms co-occur in soils: cell respiration and EXOMET. The isotopic fractionation induced by the EXOMET open perspectives for its quantification in non-sterilized living soils.

  13. Evaluation Of Sensitivity Of Mass-independent Oxygen Isotopes In Aerosol Nitrate To Environmental Factors Using A Photochemical Box Model

    NASA Astrophysics Data System (ADS)

    Dominguez, G.; Wilkins, G.; Jackson, T.; Brothers, L.; McCabe, J.; Thiemens, M. H.

    2007-12-01

    An existing photochemical box model for use in polluted marine boundary layers was modified to allow for the explicit tracking of the mass-independent isotopic composition of oxygen in aerosol nitrate as well as other atmospheric species such as OH and H2O2. This modified model was then used to study the sensitivity of the mass-independent isotopic composition of atmospheric nitrate(HNO3) to variables such as relative humidity, temperature ozone and NOx concentrations. Here we present the results of these studies and compare model predictions of the mass-independent oxygen isotopic composition of aerosol nitrate to measurements taken in fine (<1micron) and coarse (>1 micron) aerosol samples taken in a variety of locations, from coastal urban environments, the tropics (Ecuador), inland California (Riverside), and Antarctica. Regarding Antarctica, we comment on the isotopic composition of OH there and the ramifications of these findings for the isotopic composition of other oxygen bearing compounds in the Antarctic atmosphere.

  14. Controlling factors of Ca isotope fractionation in scleractinian corals evaluated by temperature, pH and light controlled culture experiments

    NASA Astrophysics Data System (ADS)

    Inoue, Mayuri; Gussone, Nikolaus; Koga, Yasuko; Iwase, Akihiro; Suzuki, Atsushi; Sakai, Kazuhiko; Kawahata, Hodaka

    2015-10-01

    In this study, the 44Ca/40Ca ratios of Porites australiensis grown under three different culture experiments composed of temperature, pH and light controlled culture experiments are measured. The temperature dependent isotope fractionation of 0.02‰/°C deduced from this study is similar to inorganic aragonite, but the degree of isotope fractionation is about +0.4‰ offset in corals. These observations agree with earlier results on different coral species, suggesting Ca isotope fractionation during Ca transmembrane transport in corals. While in cultured corals a significant temperature dependence of δ44Ca is observed, the relationships between calcium isotope fractionation and pH as well as light intensity are negligible. Therefore variation of δ44Ca in Porites corals is mainly controlled by temperature. A combination of δ44Ca and Sr/Ca of corals in temperature controlled experiments cannot be explained by Rayleigh type fractionation directly from a fluid, which is seawater-like in terms of δ44Ca and Sr/Ca. Through coral-specific biomineralization processes, overall mean δ44Ca of scleractinian corals including previous studies are different from biogenic aragonites secreted by sclerosponges and pteropods, but are comparable with those of bivalves as well as calcitic coccolithophores and foraminifers. These findings are important for better understanding biomineralization in corals and in order to constrain the Ca isotopic composition of oceanic Ca sinks in response to climate changes and associated with shifts of calcite and aragonite seas.

  15. Differential accelerometer for equivalence principle tests: the common mode rejection factor and separation of signal from noise

    NASA Astrophysics Data System (ADS)

    Iafolla, V.; Lucchesi, D. M.; Nozzoli, S.; Santoli, F.; Lorenzini, E. C.; Shapiro, I. I.; Ashenberg, J.; Bombardelli, C.; Glashow, S.

    Testing the Equivalence Principle EP with an accuracy higher than the present state of the art requires to detect a very small signal out of the instrument s intrinsic noise and to the quite high common mode signals acting on the pair of test masses constituting the differential accelerometer Usually the rotation of the experiment permits to modulate the violation signal at a frequency separated from other signals with frequencies associated with the motion orbital or not of the instrument carrier and gravity gradients The possibility to detect the very small violation signal is related with a very high value for the Common Mode Rejection Factor CMRF and the separation of the differential signal due to a possible EP violation from the differential signal due to the gravity gradients Will be presented an experiment under development by our team TEPEE GReAT to test for a violation of the EP in an Einstein Elevator Particular emphasis on the experimental activity concerning the implementation of the differential accelerometer to its CMRF and the indication on the algorithm to separate the signal from noise sources will be given A numerical simulation of the detector s dynamics in the presence of relevant perturbations having assumed realistic errors and construction imperfections will be also presented In the experiment the detector spins about a horizontal axis while free falling for about 25 s in vacuum inside a co-moving capsule released from a stratospheric balloon A possible EP violation signal of a few parts in 10 15 needs to be extracted from the

  16. Separating method factors and higher order traits of the Big Five: a meta-analytic multitrait-multimethod approach.

    PubMed

    Chang, Luye; Connelly, Brian S; Geeza, Alexis A

    2012-02-01

    Though most personality researchers now recognize that ratings of the Big Five are not orthogonal, the field has been divided about whether these trait intercorrelations are substantive (i.e., driven by higher order factors) or artifactual (i.e., driven by correlated measurement error). We used a meta-analytic multitrait-multirater study to estimate trait correlations after common method variance was controlled. Our results indicated that common method variance substantially inflates trait correlations, and, once controlled, correlations among the Big Five became relatively modest. We then evaluated whether two different theories of higher order factors could account for the pattern of Big Five trait correlations. Our results did not support Rushton and colleagues' (Rushton & Irwing, 2008; Rushton et al., 2009) proposed general factor of personality, but Digman's (1997) α and β metatraits (relabeled by DeYoung, Peterson, and Higgins (2002) as Stability and Plasticity, respectively) produced viable fit. However, our models showed considerable overlap between Stability and Emotional Stability and between Plasticity and Extraversion, raising the question of whether these metatraits are redundant with their dominant Big Five traits. This pattern of findings was robust when we included only studies whose observers were intimately acquainted with targets. Our results underscore the importance of using a multirater approach to studying personality and the need to separate the causes and outcomes of higher order metatraits from those of the Big Five. We discussed the implications of these findings for the array of research fields in which personality is studied.

  17. 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.

  18. Intracellular Cadmium Isotope Fractionation

    NASA Astrophysics Data System (ADS)

    Horner, T. J.; Lee, R. B.; Henderson, G. M.; Rickaby, R. E.

    2011-12-01

    Recent stable isotope studies into the biological utilization of transition metals (e.g. Cu, Fe, Zn, Cd) suggest several stepwise cellular processes can fractionate isotopes in both culture and nature. However, the determination of fractionation factors is often unsatisfactory, as significant variability can exist - even between different organisms with the same cellular functions. Thus, it has not been possible to adequately understand the source and mechanisms of metal isotopic fractionation. In order to address this problem, we investigated the biological fractionation of Cd isotopes within genetically-modified bacteria (E. coli). There is currently only one known biological use or requirement of Cd, a Cd/Zn carbonic anhydrase (CdCA, from the marine diatom T. weissfloggii), which we introduce into the E. coli genome. We have also developed a cleaning procedure that allows for the treating of bacteria so as to study the isotopic composition of different cellular components. We find that whole cells always exhibit a preference for uptake of the lighter isotopes of Cd. Notably, whole cells appear to have a similar Cd isotopic composition regardless of the expression of CdCA within the E. coli. However, isotopic fractionation can occur within the genetically modified E. coli during Cd use, such that Cd bound in CdCA can display a distinct isotopic composition compared to the cell as a whole. Thus, the externally observed fractionation is independent of the internal uses of Cd, with the largest Cd isotope fractionation occurring during cross-membrane transport. A general implication of these experiments is that trace metal isotopic fractionation most likely reflects metal transport into biological cells (either actively or passively), rather than relating to expression of specific physiological function and genetic expression of different metalloenzymes.

  19. 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.

  20. Separation and measurement of Pa, Th, and U isotopes in marine sediments by microwave-assisted digestion and multiple collector inductively coupled plasma mass spectrometry.

    PubMed

    Negre, César; Thomas, Alexander L; Mas, José Luis; Garcia-Orellana, Jordi; Henderson, Gideon M; Masqué, Pere; Zahn, Rainer

    2009-03-01

    This manuscript describes a new protocol for determination of Pa/Th/U in marine sediments. It is based on microwave-assisted digestion and represents an important reduction of working time over conventional hot-plate digestion methods, and the use of HClO(4) is avoided. Although Th and U are completely dissolved with a first microwave step, around 40% of (231)Pa remains undissolved, and a short hot-plate step with reverse aqua regia is required to achieve total digestion and spike equilibration. Next, the method involves a separation of these elements and a further purification of the Pa fraction using Dowex AG1-X8 resin. Separation with Bio-Rad and Sigma-Aldrich resins was compared; although both perform similarly for Th and U, Pa yields are higher with Bio-Rad. Finally, samples are measured using a Nu instruments multiple collector inductively coupled plasma mass spectrometer (MC-ICPMS). Overall chemical yields range around 50% for Pa, 60% for Th, and 70% for U.

  1. Separation and quantification of silver nanoparticles and silver ions using reversed phase high performance liquid chromatography coupled to inductively coupled plasma mass spectrometry in combination with isotope dilution analysis.

    PubMed

    Sötebier, Carina A; Weidner, Steffen M; Jakubowski, Norbert; Panne, Ulrich; Bettmer, Jörg

    2016-10-14

    A reversed phase high performance liquid chromatography coupled to an inductively coupled plasma mass spectrometer (HPLC-ICP-MS) approach in combination with isotope dilution analysis (IDA) for the separation and parallel quantification of nanostructured and ionic silver (Ag) is presented. The main focus of this work was the determination of the ionic Ag concentration. For a sufficient stabilization of the ions without dissolving the nanoparticles (NPs), the eluent had to be initially optimized. The determined Ag ion concentration was in a good agreement with results obtained using ultrafiltration. Further, the mechanism of the NP separation in the HPLC column was investigated. Typical size exclusion effects were found by comparing results from columns with different pore sizes. Since the recovery rates decreased with increasing Ag NP size and large Ag NPs did not elute from the column, additional interactions of the particles with the stationary phase were assumed. Our results reveal that the presented method is not only applicable to Ag NPs, but also to gold and polystyrene NPs. Finally, IDA-HPLC-ICP-MS experiments in single particle mode were performed to determine the particle cut-off size. The comparison with conventional spICP-MS experiments resulted in a similar diameter and particle size distribution.

  2. Calcium isotopes in wine

    NASA Astrophysics Data System (ADS)

    Holmden, C. E.

    2011-12-01

    The δ 44/40Ca values of bottled wine vary between -0.76% to -1.55% on the seawater scale and correlate weakly with inverse Ca concentration and Mg/Ca ratio, such that the lowest δ 44/40Ca values have the highest Ca concentrations and lowest Mg/Ca ratios. The correlation is notable in the sense that the measured wines include both whites and reds sampled from different wine growing regions of the world, and cover a wide range of quality. Trends among the data yield clues regarding the cause of the observed isotopic fractionation. White wines, and wines generally perceived to be of lower quality, have lower δ 44/40Ca values compared to red wines and wines of generally perceived higher quality. Quality was assessed qualitatively through sensory evaluation, price, and scores assigned by critics. The relationship between δ 44/40Ca and wine quality was most apparent when comparing wines of one varietal from one producer from the same growing region. In the vineyard, wine quality is related to factors such as the tonnage of the crop and the ripeness of the grapes at the time of harvesting, the thickness of the skins for reds, the age of the vines, as well as the place where the grapes were grown (terroir). Quality is also influenced by winemaking practices such as fermentation temperature, duration of skin contact, and barrel ageing. Accordingly, the relationship between δ 44/40Ca and wine quality may originate during grape ripening in the vineyard or during winemaking in the cellar. We tested the grape ripening hypothesis using Merlot grapes sampled from a vineyard in the Okanagan, British Columbia, using sugar content (degrees Brix) as an indicator of ripeness. The grapes were separated into pulp, skin, and pip fractions and were analyzed separately. Thus far, there is no clear evidence for a systematic change in δ 44/40Ca values associated with progressive ripening of grapes in the vineyard. On the day of harvesting, the δ 44/40Ca value of juice squeezed from

  3. Model of pediatric pituitary hormone deficiency separates the endocrine and neural functions of the LHX3 transcription factor in vivo

    PubMed Central

    Colvin, Stephanie C.; Malik, Raleigh E.; Showalter, Aaron D.; Sloop, Kyle W.; Rhodes, Simon J.

    2011-01-01

    The etiology of most pediatric hormone deficiency diseases is poorly understood. Children with combined pituitary hormone deficiency (CPHD) have insufficient levels of multiple anterior pituitary hormones causing short stature, metabolic disease, pubertal failure, and often have associated nervous system symptoms. Mutations in developmental regulatory genes required for the specification of the hormone-secreting cell types of the pituitary gland underlie severe forms of CPHD. To better understand these diseases, we have created a unique mouse model of CPHD with a targeted knockin mutation (Lhx3 W227ter), which is a model for the human LHX3 W224ter disease. The LHX3 gene encodes a LIM-homeodomain transcription factor, which has essential roles in pituitary and nervous system development in mammals. The introduced premature termination codon results in deletion of the carboxyl terminal region of the LHX3 protein, which is critical for pituitary gene activation. Mice that lack all LHX3 function do not survive beyond birth. By contrast, the homozygous Lhx3 W227ter mice survive, but display marked dwarfism, thyroid disease, and female infertility. Importantly, the Lhx3 W227ter mice have no apparent nervous system deficits. The Lhx3 W227ter mouse model provides a unique array of hormone deficits and facilitates experimental approaches that are not feasible with human patients. These experiments demonstrate that the carboxyl terminus of the LHX3 transcription factor is not required for viability. More broadly, this study reveals that the in vivo actions of a transcription factor in different tissues are molecularly separable. PMID:21149718

  4. The effects of sex, tissue type, and dietary components on stable isotope discrimination factors (Δ13C and Δ15N) in mammalian omnivores.

    PubMed

    Kurle, Carolyn M; Koch, Paul L; Tershy, Bernie R; Croll, Donald A

    2014-01-01

    We tested the effects of sex, tissue, and diet on stable isotope discrimination factors (Δ(13)C and Δ(15)N) for six tissues from rats fed four diets with varied C and N sources, but comparable protein quality and quantity. The Δ(13)C and Δ(15)N values ranged from 1.7-4.1‰ and 0.4-4.3‰, respectively. Females had higher Δ(15)N values than males because males grew larger, whereas Δ(13)C values did not differ between sexes. Differences in Δ(13)C values among tissue types increased with increasing variability in dietary carbon sources. The Δ(15)N values increased with increasing dietary δ(15)N values for all tissues except liver and serum, which have fast stable isotope turnover times, and differences in Δ(15)N values among tissue types decreased with increasing dietary animal protein. Our results demonstrate that variability in dietary sources can affect Δ(13)C values, protein source affects Δ(15)N values even when protein quality and quantity are controlled, and the isotope turnover rate of a tissue can influence the degree to which diet affects Δ(15)N values.

  5. 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.

  6. The Clinical Significance of Separate Measurements of Carotid Arterial Wall to Assess the Risk Factor for Atherosclerosis

    PubMed Central

    Kim, Ji-Hoon; Kim, Gee-Hee; Moon, Keon-Woong; Yoo, Ki-Dong; Kim, Chul-Min

    2016-01-01

    Background Carotid intima-media thickness (CIMT) is associated with several risk factors for atherosclerosis and has been consistently linked to cardiovascular and cerebrovascular disease. The clinical significance of separate measurements of CIMT, which is the sum of the intima (IT) and media thickness (MT), to use as an assessment of risk for atherosclerosis has not yet been fully established. Methods Among 3377 patients who underwent B-mode ultrasound of carotid arteries and coronary angiography in the Medical Department of St. Mary's Hospital from September 2003 to March 2009, 1146 subjects (M:F = 616:530; mean age, 57.7 ± 12.1 years) who were diagnosed with normal coronary arteries were enrolled in this study. IT, MT, and CIMT of the enrolled patients were manually measured using high-frequency ultrasonography (15 MHz linear array transducer). Results In multivariate logistic regression analysis, age (β = 0.063, p < 0.0001), body mass index (BMI) (β = 0.028, p = 0.018), and hypertension (HTN) (β = 0.046, p = 0.0002) were associated with MT (R2 = 0.256) and the IT/MT ratio (R2 = 0.209). Age (β = 0.065, p < 0.0001), BMI (β = 0.025, p = 0.038), hemoglobin A1c (β = 0.045, p = 0.045), and HTN (β = 0.043, p = 0.0006) correlated with mean CIMT (R2 = 0.230). Age (β = -0.071, p < 0.0001) and BMI (β = -0.046, p = 0.002) were associated with the IT/MT ratio (R2 = 0.219) on the left side. Age (β = 0.093, p < 0.0001) was related to MT (R2 = 0.265) and mean CIMT (R2 = 0.243) on the left side. Conclusion We noted different atherosclerotic risk factors were related to measurements of the arterial wall in different ways. Therefore, separate measurements of CIMT might be a useful method to assess the risk for atherosclerosis. PMID:27081444

  7. Vapor phase exsolution as a controlling factor in hydrogen isotope variation in granitic rocks: the Notch Peak granitic stock, Utah

    USGS Publications Warehouse

    Nabelek, P.I.; O'Neil, J.R.; Papike, J.J.

    1983-01-01

    The Notch Peak granitic stock, western Utah, is comprised of three concentric sequentially intruded rock types, from granite at the rim, to quartz monzonite I, to quartz monzonite II at the core. The ??18O values of whole rocks vary about an average of 9.4 (SMOW), irrespective of the rock type and position relative to contact, suggesting that the three magmas had the same parent. The whole rock ??D values in the stock range from -100 to -55. ??D values increase toward the cores of both quartz monzonite I and quartz monzonite II, resulting in concentric contours. The ??D contours of quartz monzonite II cross-cut those of quartz monzonite I, suggesting little isotopic interaction between these bodies and the absence of a late pervasive fluid phase. There is a positive correlation between ??D values and water content of the samples, where samples from each body define a distinct field. The positive correlation is explained by isotopic fractionation attendant on vapor exsolution from the crystallizing magma. An observed increase in ??D with the degree of chloritization, a trend opposite to that observed in systems where participation of meteoric water has been demonstrated, is the result of subsolidus interaction with the exsolved fluids. These results show that large variations in the hydrogen isotope ratios of a granitoid can arise by exsolution of a vapor phase from the melt on crystallization. In general, magmas with larger modal amount of primary hydrous phases will tend to have higher ??D values than those with small amounts of hydrous phases. Furthermore, the relatively high ??D values of chlorites at Notch Peak confirm the applicability of classical concepts of closed-system deuteric alteration to some granitoid bodies. Thus, meteoric water interaction need not be always invoked to explain hydrogen isotope variation and deuteric alteration in granitoids. ?? 1983.

  8. Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from laboratory culturing experiment

    NASA Astrophysics Data System (ADS)

    Zhang, N.; Yamada, K.; Suzuki, N.; Yoshida, N.

    2014-10-01

    The carbon isotopic composition (δ13C) of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone). However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail subspecies, Acusta despecta sieboldiana, collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on results obtained from previous works and this study, a simple but credible framework is presented to illustrate how each source and environmental parameter affects shell carbonate δ13C values. According to this framework and some reasonable assumptions, we estimated the contributions of different carbon sources for each snail individual: for cabbage-fed (C3 plant) groups, the contributions of diet, atmospheric CO2, and ingested limestone vary in the ranges of 66-80, 16-24, and 0-13%, respectively. For corn-fed (C4 plant) groups, because of the possible food stress (less ability to consume C4 plants), the values vary in the ranges of 56-64, 18-20, and 16-26%, respectively. Moreover, according to the literature and our observations, the subspecies we cultured in this study show preferences towards different plant species for food. Therefore, we suggest that the potential food preference should be considered adequately for some species in paleoenvironment studies. Finally, we inferred that only the isotopic exchange of the calcite-HCO3--aragonite equilibrium during egg laying and hatching of our cultured snails controls carbon isotope fractionation.

  9. Factors controlling shell carbon isotopic composition of land snail Acusta despecta sieboldiana estimated from lab culturing experiment

    NASA Astrophysics Data System (ADS)

    Zhang, N.; Yamada, K.; Suzuki, N.; Yoshida, N.

    2014-05-01

    The carbon isotopic composition (δ13C) of land snail shell carbonate derives from three potential sources: diet, atmospheric CO2, and ingested carbonate (limestone). However, their relative contributions remain unclear. Under various environmental conditions, we cultured one land snail species, Acusta despecta sieboldiana collected from Yokohama, Japan, and confirmed that all of these sources affect shell carbonate δ13C values. Herein, we consider the influences of metabolic rates and temperature on the carbon isotopic composition of the shell carbonate. Based on previous works and on results obtained in this study, a simple but credible framework is presented for discussion of how each source and environmental parameter can affect shell carbonate δ13C values. According to this framework and some reasonable assumptions, we have estimated the contributions of different carbon sources for each snail individual: for cabbage (C3 plant) fed groups, the contributions of diet, atmospheric CO2 and ingested limestone respectively vary as 66-80%, 16-24%, and 0-13%. For corn (C4 plant) fed groups, because of the possible food stress (lower consumption ability of C4 plant), the values vary respectively as 56-64%, 18-20%, and 16-26%. Moreover, we present new evidence that snails have discrimination to choose C3 and C4 plants as food. Therefore, we suggest that food preferences must be considered adequately when applying δ13C in paleo-environment studies. Finally, we inferred that, during egg laying and hatching of our cultured snails, carbon isotope fractionation is controlled only by the isotopic exchange of the calcite-HCO3--aragonite equilibrium.

  10. Synergism and separation factors in lanthanide extraction with mixtures of chelating extractant and amine salts in C{sub 6}H{sub 6}

    SciTech Connect

    Dukov, I.L.; Jordanov, V.M.

    1997-10-01

    The solvent extraction of Pr, Gd, and Yb with 1-phenyl-3-methyl-4-benzoylpyrazol-5-one (HP) and an amine salt (AmHA) has been studied. The composition of the extracted species has been determined as (AmH)[LnP{sub 4}]. The values of the synergistic coefficients and separation factors have been calculated. The effect of the amine salt on the extraction and separation of lanthanides has been discussed.

  11. ADP-ribosylation of translation elongation factor 2 by diphtheria toxin in yeast inhibits translation and cell separation.

    PubMed

    Mateyak, Maria K; Kinzy, Terri Goss

    2013-08-23

    Eukaryotic translation elongation factor 2 (eEF2) facilitates the movement of the peptidyl tRNA-mRNA complex from the A site of the ribosome to the P site during protein synthesis. ADP-ribosylation (ADP(R)) of eEF2 by bacterial toxins on a unique diphthamide residue inhibits its translocation activity, but the mechanism is unclear. We have employed a hormone-inducible diphtheria toxin (DT) expression system in Saccharomyces cerevisiae which allows for the rapid induction of ADP(R)-eEF2 to examine the effects of DT in vivo. ADP(R) of eEF2 resulted in a decrease in total protein synthesis consistent with a defect in translation elongation. Association of eEF2 with polyribosomes, however, was unchanged upon expression of DT. Upon prolonged exposure to DT, cells with an abnormal morphology and increased DNA content accumulated. This observation was specific to DT expression and was not observed when translation elongation was inhibited by other methods. Examination of these cells by electron microscopy indicated a defect in cell separation following mitosis. These results suggest that expression of proteins late in the cell cycle is particularly sensitive to inhibition by ADP(R)-eEF2.

  12. Integration of the AVLIS (atomic vapor laser isotopic separation) process into the nuclear fuel cycle. [Effect of AVLIS feed requirements on overall fuel cycle

    SciTech Connect

    Hargrove, R.S.; Knighton, J.B.; Eby, R.S.; Pashley, J.H.; Norman, R.E.

    1986-08-01

    AVLIS RD and D efforts are currently proceeding toward full-scale integrated enrichment demonstrations in the late 1980's and potential plant deployment in the mid 1990's. Since AVLIS requires a uranium metal feed and produces an enriched uranium metal product, some change in current uranium processing practices are necessitated. AVLIS could operate with a UF/sub 6/-in UF/sub 6/-out interface with little effect to the remainder of the fuel cycle. This path, however, does not allow electric utility customers to realize the full potential of low cost AVLIS enrichment. Several alternative processing methods have been identified and evaluated which appear to provide opportunities to make substantial cost savings in the overall fuel cycle. These alternatives involve varying levels of RD and D resources, calendar time, and technical risk to implement and provide these cost reduction opportunities. Both feed conversion contracts and fuel fabricator contracts are long-term entities. Because of these factors, it is not too early to start planning and making decisions on the most advantageous options so that AVLIS can be integrated cost effectively into the fuel cycle. This should offer economic opportunity to all parties involved including DOE, utilities, feed converters, and fuel fabricators. 10 refs., 11 figs., 2 tabs.

  13. Distinct Trajectories of Separation Anxiety in the Preschool Years: Persistence at School Entry and Early-Life Associated Factors

    ERIC Educational Resources Information Center

    Battaglia, Marco; Touchette, Évelyne; Garon-Carrier, Gabrielle; Dionne, Ginette; Côté, Sylvana M.; Vitaro, Frank; Tremblay, Richard E.; Boivin, Michel

    2016-01-01

    Background: Little is known about how children differ in the onset and evolution of separation anxiety (SA) symptoms during the preschool years, and how SA develops into separation anxiety disorder. In a large, representative population-based sample, we investigated the developmental trajectories of SA symptoms from infancy to school entry, their…

  14. Fractionation of strontium isotopes in cation-exchange chromatography

    SciTech Connect

    Oi, Takao; Ogino, Hideki; Kakihana, Hidetake ); Hosoe, Morikazu )

    1992-04-01

    Strontium isotope fractionation has been observed in cation-exchange chromatography of strontium salts. The heavier isotopes have been found enriched at the front parts of displacement-type chromatograms, which means that the heavier isotopes are preferentially fractionated into the solution phase. The average values of the single-stage separation factor (S) minus one per unit mass difference between isotopes have been 1.0 {times} 10{sup {minus}6} for the strontium chloride system, 2.9 {times} 10{sup {minus}6} for the strontium acetate system, and 3.1 {times} 10{sup {minus}6} for the strontium lactate system at 25C. No evidence of the odd-even anomalous isotope effects has been observed. The isotopic reduced partition function ratios (RPFRs) of the strontium species involved in the present study have been estimated; the RPFRs of the complex species have been found to be larger than that of simple hydrated strontium lactate and strontium acetate systems are larger than that of the strontium chloride system.

  15. PAPIN: A Fortran-IV program to calculate cross section probability tables, Bondarenko and transmission self-shielding factors for fertile isotopes in the unresolved resonance region

    SciTech Connect

    Munoz-Cobos, J.G.

    1981-08-01

    The Fortran IV code PAPIN has been developed to calculate cross section probability tables, Bondarenko self-shielding factors and average self-indication ratios for non-fissile isotopes, below the inelastic threshold, on the basis of the ENDF/B prescriptions for the unresolved resonance region. Monte-Carlo methods are utilized to generate ladders of resonance parameters in the unresolved resonance region, from average resonance parameters and their appropriate distribution functions. The neutron cross-sections are calculated by the single level Breit-Wigner (SLBW) formalism, with s, p and d-wave contributions. The cross section probability tables are constructed by sampling the Doppler-broadened cross sections. The various self-shielded factors are computed numerically as Lebesgue integrals over the cross section probability tables. The program PAPIN has been validated through extensive comparisons with several deterministic codes.

  16. Corticotropin-releasing factor modulates maternal separation-induced ultrasonic vocalization in rat pups via activation of CRF1 receptor.

    PubMed

    Ise, Satoko; Nagano, Norihiro; Okuda, Shoki; Ohta, Hisashi

    2008-10-09

    An infant animal isolated from its mother emits vocalizations spanning from the audible to the ultrasonic. These vocalizations are believed to represent distress signals from the pup. However, the neurobiological basis for vocalizations elicited by isolation has not been well characterized under different environmental conditions. The present study was designed to clarify the role of the corticotropin-releasing factor (CRF) system in vocalizations elicited by isolating a rat pup at ambient temperatures of 37 degrees C (temperature of the nest in which the mother and littermates are present) and 24 degrees C (room temperature). Sprague-Dawley rat pups at 7 days old were isolated from their dam, then the number of vocalizations was measured for 5 min. The number of vocalizations increased when ambient temperature was changed from 37 degrees C to 24 degrees C. Systemic administration of CRF (3 or 10 mg/kg) increased the number of vocalizations at 37 degrees C in a dose-dependent manner. CRF-induced increases in the number of vocalizations at 3 mg/kg were completely blocked by a selective CRF1 receptor antagonist, NBI27914 (3 mg/kg), but not by a selective CRF2 receptor antagonist, K41498 (3 mg/kg). NBI27914 (30 mg/kg), but not K41498 (3 mg/kg), suppressed the increased number of vocalizations at 24 degrees C. These results demonstrate involvement of the CRF-CRF1 receptor regulatory system on the modulation of ultrasonic vocalizations by rat pups separated from their dam.

  17. Atmospheric Pb deposition since the Industrial Revolution recorded by five Swiss peat profiles: Enrichment factors, fluxes, isotopic composition, and sources

    SciTech Connect

    Weiss, D.; Shotyk, W.; Kramers, J.D.; Appleby, P.G.; Cheburkin, A.K.

    1999-05-01

    Atmospheric Pb deposition since the Industrial Revolution was studied in western, central, and southern Switzerland using five rural peat bogs. Similar temporal patterns were found in western and central Switzerland, with two distinct periods of Pb enrichment relative to the natural background: between 1880 and 1920 with enrichments ranging from 40 to 80 times, and between 1960 and 1980 with enrichments ranging from 80 to 100 times. The fluxes also were generally elevated in those time periods: in western Switzerland between 1.16 and 1.55 {micro}g cm{sup {minus}2} y{sup {minus}1} during the second period. Between the Industrial Revolution and 1985, nonradiogenic Pb became increasingly important in all five cores because of the replacement of coal by oil after ca. 1920, the use of Australian Pb in industry, and the extensive combustion of leaded gasoline after 1950. The introduction of unleaded gasoline in 1985 had a pronounced effect on the Pb deposition in all five cores. Enrichments dropped sharply, and the isotopic ratios reverted back toward natural values. The cores from western and central Switzerland showed very similar isotopic trends throughout the time period studied, implying that these sites were influenced contemporaneously by similar pollution sources and atmospheric pathways. Southern Switzerland revealed a different record with respect to the Pb pollution: it was dominated by a single massive Pb enrichment dated between 1930 and 1950.

  18. Factors influencing the separation of oligonucleotides using reversed-phase/ion-exchange mixed-mode high performance liquid chromatography columns.

    PubMed

    Biba, Mirlinda; Jiang, Eileen; Mao, Bing; Zewge, Daniel; Foley, Joe P; Welch, Christopher J

    2013-08-23

    New mixed-mode columns consisting of reversed-phase and ion-exchange separation modes were evaluated for the analysis of short RNA oligonucleotides (∼20mers). Conventional analysis for these samples typically involves using two complementary methods: strong anion-exchange liquid chromatography (SAX-LC) for separation based on charge, and ion-pair reversed-phase liquid chromatography (IP-RPLC) for separation based on hydrophobicity. Recently introduced mixed-mode high performance liquid chromatography (HPLC) columns combine both reversed-phase and ion-exchange modes, potentially offering a simpler analysis by combining the benefits of both separation modes into a single method. Analysis of a variety of RNA oligonucleotide samples using three different mixed-mode stationary phases showed some distinct benefits for oligonucleotide separation and analysis. When using these mixed-mode columns with typical IP-RPLC mobile phase conditions, such as ammonium acetate or triethylammonium acetate as the primary ion-pair reagent, the separation was mainly based on the IP-RPLC mode. However, when changing the mobile phase conditions to those more typical for SAX-LC, such as salt gradients with NaCl or NaBr, very different separation patterns were observed due to mixed-mode interactions. In addition, the Scherzo SW-C18 and SM-C18 columns with sodium chloride or sodium bromide salt gradients also showed significant improvements in peak shape.

  19. Study of factors governing oil-water separation process using TiO₂ films prepared by spray deposition of nanoparticle dispersions.

    PubMed

    Gondal, Mohammed A; Sadullah, Muhammad S; Dastageer, Mohamed A; McKinley, Gareth H; Panchanathan, Divya; Varanasi, Kripa K

    2014-08-27

    Surfaces which possess extraordinary water attraction or repellency depend on surface energy, surface chemistry, and nano- and microscale surface roughness. Synergistic superhydrophilic-underwater superoleophobic surfaces were fabricated by spray deposition of nanostructured TiO2 on stainless steel mesh substrates. The coated meshes were then used to study gravity driven oil-water separation, where only the water from the oil-water mixture is allowed to permeate through the mesh. Oil-water separation efficiencies of up to 99% could be achieved through the coated mesh of pore sizes 50 and 100 μm, compared to no separation at all, that was observed in the case of uncoated meshes of the same material and pore sizes. An adsorbed water on the TiO2 coated surface, formation of a water-film between the wires that form the mesh and the underwater superoleophobicity of the structured surface are the key factors that contribute to the enhanced efficiency observed in oil-water separation. The nature of the oil-water separation process using this coated mesh (in which the mesh allows water to pass through the porous structure but resists wetting by the oil phase) minimizes the fouling of mesh so that the need for frequent replacement of the separating medium is reduced. The fabrication approach presented here can be applied for coating large surface areas and to develop a large-scale oil-water separation facility for oil-field applications and petroleum industries.

  20. Factors influencing base flow in the Swiss Midlands - Can results from different base flow separation methods help to identify these factors?

    NASA Astrophysics Data System (ADS)

    Meyer, Raphael; Schädler, Bruno; Viviroli, Daniel; Weingartner, Rolf

    2010-05-01

    Base flow is a desirable entity to know, for water management in general and particularly for climate change impact studies. Base flow is most often defined as that part of total discharge which origins from delayed storages in a river catchment. During a prolonged period without rain, base flow is the sole contributor to discharge. Base flow therefore makes a river perennial. A high base flow contribution to total annual discharge makes a river more stable in respect of meteorological droughts. Annual base flow from a catchment cannot be determined exactly. Only total discharge can be measured with high accuracy. Therefore, base flow has to be estimated with appropriate methods. Calculating an entity which cannot be verified by measurements is easy. By defining the entity with a calculation procedure, the result is numerically always right. It is actually much more difficult to understand the results, i.e. how these outcomes should be interpreted. The present study investigates the application of three different base flow separation procedures for numerous (up to 40) meso-scale catchments in Switzerland. The methods Demuth (1993), Wittenberg (1999) and Institute of Hydrology (1980) are different approaches to determine base flow, based on daily runoff data. The method Demuth, and the separation of base flow according to Institute of Hydrology, are statistical methods. Demuth is based on the graphical approach of Kille (1970), and the procedure of the Institute of Hydrology is an empirical smoothing method. In contrast to this, the method by Wittenberg does not presume linearity between storage and outflow. Analyzing the results, among each other and in comparison with physiographic characteristics of the catchments under consideration, leads to a more detailed picture of the ongoing processes. At least the dominant control factors for base flow in the Swiss Midlands should be detectable. These are expected to be found first of all among geology and climate, which

  1. Diurnal, seasonal and interannual variability of carbon isotope discrimination at the canopy level in response to environmental factors in a boreal forest ecosystem.

    PubMed

    Chen, Baozhang; Chen, Jing M

    2007-10-01

    Accurate estimation of temporal and spatial variations in photosynthetic discrimination of 13C is critical to carbon cycle research. In this study, a combined ecosystem-boundary layer isotope model, which was satisfactorily validated against intensive campaign data, was used to explore the temporal variability of carbon discrimination in response to environmental driving factors in a boreal ecosystem in the vicinity of Fraserdale Tower, Ontario, Canada (49 degrees 52'30''N, 81 degrees 34'12''W). A 14 year (1990-1996 and 1998-2004) hourly CO2 concentration and meteorological record measured on this tower was used for this purpose. The 14 year mean yearly diurnal amplitude of canopy-level discrimination Delta(canopy) was computed to be 2.8 +/- 0.5 per thousand, and the overall diurnal cycle showed that the greatest Delta(canopy) values occurred at dawn and dusk, while the minima generally appeared in mid-afternoon. The average annual Delta(canopy) varied from 18.3 to 19.7 per thousand with the 14 year average of 19 +/- 0.4 per thousand. The overall seasonality of Delta(canopy) showed a gradually increasing trend from leaf emergence in May-September and with a slight decrease at the end of the growing season in October. Delta(canopy) was negatively correlated to vapour pressure deficit and air temperature across hourly to decadal timescales. A strong climatic control on stomatal regulation of ecosystem isotope discrimination was found in this study.

  2. The δ13C evolution of cave drip water along discreet flow paths in a central Texas cave: Quantifying kinetic isotope fractionation factors

    NASA Astrophysics Data System (ADS)

    Mickler, P. J.; Carlson, P. E.; Banner, J.; Breecker, D.; Stern, L. A.; Baseman, A.

    2015-12-01

    Gaps remain in our understanding of in-cave processes that influence cave water chemistry during speleothem formation. Quantifying environmental controls on the isotopic and chemical evolution of karst groundwater would improve the accuracy of speleothem-based paleoclimate reconstructions. In this study, drip water chemical evolution along flow paths was sampled monthly at two locations in Inner Space Cavern, Texas, over a period of 8 months. In each of the two locations, cave water drips off a stalactite, flows along a flowstone and subsequently drips off a lower stalactite, allowing cave water to be sampled at two points, 1-2 meters apart, along each flow path. The chemical and isotopic evolution of drip water along its flow path shows seasonality, where 1) summer months (high cave-air pCO2) have small variations in δ13C values along the flow paths, high and relatively invariant DIC and Ca values,; and 2) winter months (low cave-air pCO2) generally have large increases in DIC δ13C values along the flow paths, lower DIC and Ca values. The magnitude of the increase in DIC δ13C values along the flow paths, <~1‰ to ~4‰, is controlled by the extent of DIC loss to CO2 degassing and calcite precipitation which is controlled by the pCO2 gradient between drip water and cave air. If the DIC loss is less than 15%, then the evolution of the δ13C value of the DIC reservoir can be modelled using a Rayleigh distillation model and equilibrium fractionation factors between (CO2(g)-HCO3-(aq)) and (CaCO3-HCO3-(aq)). As the loss of the DIC reservoir increases above 15% the DIC δ13C values become progressively higher such that the ɛ (CO2(g)-HCO3-(aq)) values needed to model the observed results change from equilibrium values of ~8‰ to non-equilibrium values up to ~25‰. The variance in magnitude of carbon isotope fractionation during CO2 degassing cannot be attributed to changes in temperature, and thus we infer significant kinetic isotope effects at higher rates of DIC

  3. Fertilizer nitrogen isotope signatures.

    PubMed

    Bateman, Alison S; Kelly, Simon D

    2007-09-01

    There has been considerable recent interest in the potential application of nitrogen isotope analysis in discriminating between organically and conventionally grown crops. A prerequisite of this approach is that there is a difference in the nitrogen isotope compositions of the fertilizers used in organic and conventional agriculture. We report new measurements of delta15N values for synthetic nitrogen fertilizers and present a compilation of the new data with existing literature nitrogen isotope data. Nitrogen isotope values for fertilizers that may be permitted in organic cultivation systems are also reported (manures, composts, bloodmeal, bonemeal, hoof and horn, fishmeal and seaweed based fertilizers). The delta15N values of the synthetic fertilizers in the compiled dataset fall within a narrow range close to 0 per thousand with 80% of samples lying between-2 and 2 per thousand and 98.5% of the data having delta15N values of less than 4 per thousand (mean=0.2 per thousand n=153). The fertilizers that may be permitted in organic systems have a higher mean delta15N value of 8.5 per thousand and exhibit a broader range in delta15N values from 0.6 to 36.7 per thousand (n=83). The possible application of the nitrogen isotope approach in discriminating between organically and conventionally grown crops is discussed in light of the fertilizer data presented here and with regard to other factors that are also important in determining crop nitrogen isotope values.

  4. Oxygen isotope equilibrium between eclogite minerals and its constraints on mineral Sm-Nd chronometer

    NASA Astrophysics Data System (ADS)

    Zheng, Yong-Fei; Wang, Zheng-Rong; Li, Shu-Guang; Zhao, Zi-Fu

    2002-02-01

    Sm-Nd and oxygen isotope analyses were carried out for mineral separates of ultrahigh pressure eclogites from the Sulu terrane in eastern China. The results show a direct correspondence in equilibrium or disequilibrium state between the oxygen and Sm-Nd isotope systems of eclogite minerals. The omphacite-garnet pairs of oxygen isotope equilibrium at eclogite-facies conditions yield meaningful Triassic Sm-Nd isochron ages, whereas those of oxygen isotope disequilibrium give non-Triassic ages of geological meaninglessness. This can be reasonably interpreted by the fact that the rates of oxygen diffusion in garnet and pyroxene are lower than, or close to, those of Nd diffusion, and thus attainment of isotopic equilibrium in the omphacite-garnet O system suggests achievement of Nd isotope equilibrium in the same mineral pairs. The presence or absence of fluid in the eclogite protoliths is a major rate-controlling factor for isotopic equilibration during high-grade metamorphism. It appears that the state of oxygen isotope equilibrium between cogenetic minerals can provide a critical test for the validity of the Sm-Nd mineral chronometer. In addition, the exact timing of the ultrahigh pressure metamorphism in the Dabie-Sulu terranes is constrained at Early Triassic rather than Late Triassic.

  5. Research Directed at Developing a Classical Theory to Describe Isotope Separation of Polyatomic Molecules Illuminated by Intense Infrared Radiation. Final Report for period May 7, 1979 to September 30, 1979; Extension December 31, 1997

    DOE R&D Accomplishments Database

    Lamb, W. E. Jr.

    1981-12-01

    This final report describes research on the theory of isotope separation produced by the illumination of polyatomic molecules by intense infrared laser radiation. This process is investigated by treating the molecule, sulfur hexafluoride, as a system of seven classical particles that obey the Newtonian equations of motion. A minicomputer is used to integrate these differential equations. The particles are acted on by interatomic forces, and by the time-dependent electric field of the laser. We have a very satisfactory expression for the interaction of the laser and the molecule which is compatible with infrared absorption and spectroscopic data. The interatomic potential is capable of improvement, and progress on this problem is still being made. We have made several computer runs of the dynamical behavior of the molecule using a reasonably good model for the interatomic force law. For the laser parameters chosen, we find that typically the molecule passes quickly through the resonance region into the quasi-continuum and even well into the real continuum before dissociation actually occurs. When viewed on a display terminal, the motions are exceedingly complex. As an aid to the visualization of the process, we have made a number of 16 mm movies depicting a three-dimensional representation of the motion of the seven particles. These show even more clearly the enormous complexity of the motions, and make clear the desirability of finding ways of characterizing the motion in simple ways without giving all of the numerical detail. One of the ways to do this is to introduce statistical parameters such as a temperature associated with the distribution of kinetic energies of the single particle. We have made such an analysis of our data runs, and have found favorable indications that such methods will prove useful in keeping track of the dynamical histories.

  6. An application of the theory of planned behaviour to study the influencing factors of participation in source separation of food waste

    SciTech Connect

    Karim Ghani, Wan Azlina Wan Ab.; Rusli, Iffah Farizan; Biak, Dayang Radiah Awang; Idris, Azni

    2013-05-15

    Highlights: ► Theory of planned behaviour (TPB) has been conducted to identify the influencing factors for participation in source separation of food waste using self administered questionnaires. ► The findings suggested several implications for the development and implementation of waste separation at home programme. ► The analysis indicates that the attitude towards waste separation is determined as the main predictors where this in turn could be a significant predictor of the repondent’s actual food waste separation behaviour. ► To date, none of similar have been reported elsewhere and this finding will be beneficial to local Authorities as indicator in designing campaigns to promote the use of waste separation programmes to reinforce the positive attitudes. - Abstract: Tremendous increases in biodegradable (food waste) generation significantly impact the local authorities, who are responsible to manage, treat and dispose of this waste. The process of separation of food waste at its generation source is identified as effective means in reducing the amount food waste sent to landfill and can be reused as feedstock to downstream treatment processes namely composting or anaerobic digestion. However, these efforts will only succeed with positive attitudes and highly participations rate by the public towards the scheme. Thus, the social survey (using questionnaires) to analyse public’s view and influencing factors towards participation in source separation of food waste in households based on the theory of planned behaviour technique (TPB) was performed in June and July 2011 among selected staff in Universiti Putra Malaysia, Serdang, Selangor. The survey demonstrates that the public has positive intention in participating provided the opportunities, facilities and knowledge on waste separation at source are adequately prepared by the respective local authorities. Furthermore, good moral values and situational factors such as storage convenience and

  7. 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.

  8. 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.

  9. Transuranium isotopes

    SciTech Connect

    Hoffman, D.C.

    1985-12-01

    The needs of the research community for the production of transuranium isotopes, the quantities required, the continuity of production desired, and what a new steady state neutron source would have to provide to satisfy these needs are discussed. Examples of past frontier research which need these isotopes as well as an outline of the proposed Large Einsteinium Activation Program, LEAP, which requires roughly ten times the current production of /sup 254/Es are given. 15 refs., 5 figs., 4 tabs.

  10. Isotopic chirality

    SciTech Connect

    Floss, H.G.

    1994-12-01

    This paper deals with compounds that are chiral-at least in part, due to isotope substitution-and their use in tracing the steric course of enzyme reaction in vitro and in vivo. There are other applications of isotopically chiral compounds (for example, in analyzing the steric course of nonenzymatic reactions and in probing the conformation of biomolecules) that are important but they will not be discussed in this context.

  11. An application of the theory of planned behaviour to study the influencing factors of participation in source separation of food waste.

    PubMed

    Karim Ghani, Wan Azlina Wan Ab; Rusli, Iffah Farizan; Biak, Dayang Radiah Awang; Idris, Azni

    2013-05-01

    Tremendous increases in biodegradable (food waste) generation significantly impact the local authorities, who are responsible to manage, treat and dispose of this waste. The process of separation of food waste at its generation source is identified as effective means in reducing the amount food waste sent to landfill and can be reused as feedstock to downstream treatment processes namely composting or anaerobic digestion. However, these efforts will only succeed with positive attitudes and highly participations rate by the public towards the scheme. Thus, the social survey (using questionnaires) to analyse public's view and influencing factors towards participation in source separation of food waste in households based on the theory of planned behaviour technique (TPB) was performed in June and July 2011 among selected staff in Universiti Putra Malaysia, Serdang, Selangor. The survey demonstrates that the public has positive intention in participating provided the opportunities, facilities and knowledge on waste separation at source are adequately prepared by the respective local authorities. Furthermore, good moral values and situational factors such as storage convenience and collection times are also encouraged public's involvement and consequently, the participations rate. The findings from this study may provide useful indicator to the waste management authorities in Malaysia in identifying mechanisms for future development and implementation of food waste source separation activities in household programmes and communication campaign which advocate the use of these programmes.

  12. Effects of (18)O isotopic substitution on the rotational spectra and potential splitting in the OH-OH2 complex: improved measurements for (16)OH-(16)OH2 and (18)OH-(18)OH2, new measurements for the mixed isotopic forms, and ab initio calculations of the (2)A'-(2)A" energy separation.

    PubMed

    Brauer, Carolyn S; Sedo, Galen; Dahlke, Erin; Wu, Shenghai; Grumstrup, Erik M; Leopold, Kenneth R; Marshall, Mark D; Leung, Helen O; Truhlar, Donald G

    2008-09-14

    Rotational spectra have been observed for (16)OH-(16)OH(2), (16)OH-(18)OH(2), (18)OH-(16)OH(2), and (18)OH-(18)OH(2) with complete resolution of the nuclear magnetic hyperfine structure from the OH and water protons. Transition frequencies have been analyzed for each isotopic form using the model of Marshall and Lester [J. Chem. Phys. 121, 3019 (2004)], which accounts for partial quenching of the OH orbital angular momentum and the decoupling of the electronic spin from the OH molecular axis. The analysis accounts for both the ground ((2)A(')) and first electronically excited ((2)A(")) states of the system, which correspond roughly to occupancy by the odd electron in the p(y) and p(x) orbitals, respectively (where p(y) is in the mirror plane of the complex and p(x) is perpendicular to p(y) and the OH bond axis). The spectroscopic measurements yield a parameter, rho, which is equal to the vibrationally averaged (2)A(')-(2)A(") energy separation that would be obtained if spin-orbit coupling and rotation were absent. For the parent species, rho = -146.560 27(9) cm(-1). (18)O substitution on the water increases /rho/ by 0.105 29(10) cm(-1), while substitution on the OH decreases /rho/ by 0.068 64(11) cm(-1). In the OH-OH(2) complex, the observed value of rho implies an energy spacing between the rotationless levels of the (2)A(') and (2)A(") states of 203.76 cm(-1). Ab initio calculations have been performed with quadratic configuration interaction with single and double excitations (QCISD), as well as multireference configuration interaction (MRCI), both with and without the inclusion of spin-orbit coupling. The MRCI calculations with spin-orbit coupling perform the best, giving a value of 171 cm(-1) for the (2)A(')-(2)A(") energy spacing at the equilibrium geometry. Calculations along the large-amplitude bending coordinates of the OH and OH(2) moieties within the complex are presented and are shown to be consistent with a vibrational averaging effect as the main

  13. Adaptive system for automatic stabilization of the power factor for electric drives of separation device by means of serially connected capacitors bank

    NASA Astrophysics Data System (ADS)

    Borisevich, V. D.; Juromskiy, V. M.

    2016-09-01

    A method for designing adaptive systems for automatic extremum search to stabilize the power factor of local electric power system of electric is considered. It consists in application of the serially connected capacitors compensating the reactive component of the total electric power of in parallel connected centrifugal machines usually called as an aggregate. Operation of the system just demands measuring voltage at the output of the static frequency converter for electric drives. The proposed control system is designed to stabilize the power factor close to unity in a case of alteration of parameters of a separation cascade or a single separation device in an aggregate. Such system can be operated continuously or connected occasionally depending on a technological situation. In addition, it totally excludes the phenomenon of overcompensation.

  14. Multiple linear regression for isotopic measurements

    NASA Astrophysics Data System (ADS)

    Garcia Alonso, J. I.

    2012-04-01

    There are two typical applications of isotopic measurements: the detection of natural variations in isotopic systems and the detection man-made variations using enriched isotopes as indicators. For both type of measurements accurate and precise isotope ratio measurements are required. For the so-called non-traditional stable isotopes, multicollector ICP-MS instruments are usually applied. In many cases, chemical separation procedures are required before accurate isotope measurements can be performed. The off-line separation of Rb and Sr or Nd and Sm is the classical procedure employed to eliminate isobaric interferences before multicollector ICP-MS measurement of Sr and Nd isotope ratios. Also, this procedure allows matrix separation for precise and accurate Sr and Nd isotope ratios to be obtained. In our laboratory we have evaluated the separation of Rb-Sr and Nd-Sm isobars by liquid chromatography and on-line multicollector ICP-MS detection. The combination of this chromatographic procedure with multiple linear regression of the raw chromatographic data resulted in Sr and Nd isotope ratios with precisions and accuracies typical of off-line sample preparation procedures. On the other hand, methods for the labelling of individual organisms (such as a given plant, fish or animal) are required for population studies. We have developed a dual isotope labelling procedure which can be unique for a given individual, can be inherited in living organisms and it is stable. The detection of the isotopic signature is based also on multiple linear regression. The labelling of fish and its detection in otoliths by Laser Ablation ICP-MS will be discussed using trout and salmon as examples. As a conclusion, isotope measurement procedures based on multiple linear regression can be a viable alternative in multicollector ICP-MS measurements.

  15. Stable carbon and nitrogen isotope trophic enrichment factors for Steller sea lion vibrissae relative to milk and fish/invertebrate diets

    USGS Publications Warehouse

    Stricker, Craig A.; Christ, Aaron M.; Wunder, Michael B.; Doll, Andrew C.; Farley, Sean D.; Rea, Lorrie D.; Rosen, David A. S.; Scherer, R. D.; Tollit, Dominic J.

    2015-01-01

    Nutritional constraints have been proposed as a contributor to population declines in the endangered Steller sea lion Eumetopias jubatus in some regions of the North Pacific. Isotopic analysis of vibrissae (whiskers) is a potentially useful approach to resolving the nutritional ecology of this species because long-term (up to 8 yr) dietary information is sequentially recorded and metabolically inert once formed. Additionally, vibrissae are grown in utero, potentially offering indirect inference on maternal diet. However, diet reconstruction using isotopic techniques requires a priori knowledge of trophic enrichment factors (TEFs), which can vary relative to diet quality and among animal species. In this study, we provide new TEF estimates for (1) maternal relative to pup vibrissae during both gestation and nursing and (2) adult vibrissae relative to a complex diet. Further, we refine vibrissa-milk TEFs based on an additional 76 animals with an age distribution ranging from 1 to 20 mo. Mother-pup vibrissae TEF values during gestation and nursing were near zero for δ13C and averaged 0.8 and 1.6‰, respectively, for δ15N. In contrast, vibrissa-fish/invertebrate TEFs averaged 3.3 (± 0.3 SD) and 3.7‰ (±0.3) for lipid-free δ13C and δ15N, respectively. Average lipid-free δ13C and δ15N vibrissa-milk TEFs were 2.5 (±0.9) and 1.8‰ (±0.8), respectively, and did not differ among metapopulations. Empirically determined TEFs are critical for accurate retrospective diet modeling, particularly for evaluating the hypothesis of nutritional deficiency contributing to the lack of Steller sea lion population recovery in some regions of Alaska.

  16. Factors Influencing the Stable Oxygen and Hydrogen Isotopic Composition (δ 18O and δ D) of a Subarctic Freshwater Lake Ecosystem

    NASA Astrophysics Data System (ADS)

    Wang, Y.; Wooller, M. J.

    2005-12-01

    Previous studies have shown that the stable oxygen and hydrogen isotopic compositions (δ 18O and δD) in various animal tissues can be used to examine past climates and animal migration pattern. Little attention has been paid to the relative roles of diet and water influencing the overall δ 18O and δD of animal tissues in freshwater ecosystems. It is unclear whether different trophic levels in a freshwater lake ecosystem have an identical relationship to the water that surrounds them. The δ18O and δD values of animal tissues may be controlled by numerous different factors, including metabolic and biosynthetic isotopic fractionation and variations of δ 18O and δD in the food available. We began to examine these issues by analyzing the δ 18O and δD throughout a freshwater aquatic ecosystem at Smith Lake in Alaska. We collected samples representing primary producers and consumers (primary and secondary). Samples included green algae, various aquatic plants, such as Nuphar variegatum (water lily), Polygonum amphibium (water smartweed), Carex utriculata (sedge), Utricularia vulgaris (common bladderwort), Typha latifolia (common cattail), and a range of aquatic invertebrates, including Chironomus. sp (midge), Zygoptera (damselfly), Anisoptera (dragonfly), Dytiscidae (diving beetle) and Euhirudinea (leeches). The δ 18O and δD of Smith Lake water were ~-13.5e and -129.0e, respectively, and we present the δ 18O and δD of the rest of the ecosystem relative to these data. For instance, the δ 18O of chironomus sp. was ~12.1, which is greater than the of the lake water. Preliminary results suggest the extent of the fractionation between δ 18O of chironomids vs. lake water δ 18O is consistent with previous studies. Our data provide an insight into the range of variations that could be expected within a single freshwater ecosystem.

  17. Trophic discrimination factor of nitrogen isotopes within amino acids in the dobsonfly Protohermes grandis (Megaloptera: Corydalidae) larvae in a controlled feeding experiment.

    PubMed

    Ishikawa, Naoto F; Hayashi, Fumio; Sasaki, Yoko; Chikaraishi, Yoshito; Ohkouchi, Naohiko

    2017-03-01

    The trophic discrimination factor (TDF) of nitrogen isotopes ((15)N/(14)N) within amino acids, between a stream-dwelling dobsonfly larva (Protohermes grandis: Megaloptera; Corydalidae) and its diet (chironomid larvae), was determined in controlled feeding experiments. Last-instar larvae of P. grandis were collected from the Yozawa-gawa River, central Japan, and reared in the laboratory. After fed to satiation for 1 month, one group of larvae was each fed one living chironomid larva per day for 4 weeks, while a second group was starved for 8 weeks. The larvae were harvested at intervals and the nitrogen isotopic composition of glutamic acid (δ(15)NGlu) and phenylalanine (δ(15)NPhe) were determined to calculate TDF. The mean TDF of satiated and starved larvae were 7.1‰ ± 0.5‰ (n = 3) and 7.3‰ ± 0.5‰ (n = 5), respectively. Thus, the TDF for P. grandis larvae in this study was similar to that reported for other arthropods (approximately 7‰) and was independent of satiation or starvation. A previous study of wild P. grandis larvae, based on the δ(15)NGlu and δ(15)NPhe values, estimated its trophic position (TP) as approximately 2.0 ± 0.1 (n = 5), a low value close to that of algivores, although they are generally characterized as carnivores (usually accepted as TP ≥ 3). The TDF for P. grandis larvae suggests that their low TPs in nature were caused by incorporation of vascular plant-derived amino acids (with a different δ(15)N profile from that of algae) and not by an unusually low TDF or by the effects of the satiation/starvation on amino acid metabolism.

  18. 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.

  19. Separated Shoulder

    MedlinePlus

    Separated shoulder Overview By Mayo Clinic Staff A separated shoulder is an injury to the ligaments that hold your collarbone (clavicle) to your shoulder blade. In a mild separated shoulder, the ligaments ...

  20. Oxygen and Chlorine Isotopic Fractionation During Microbial Reduction of Perchlorate

    NASA Astrophysics Data System (ADS)

    Beloso, A. D.; Sturchio, N. C.; Böhlke, J. K.; Streger, S. H.; Heraty, L. J.; Hatzinger, P. B.

    2006-12-01

    Perchlorate is a widespread environmental contaminant that has both anthropogenic and natural sources. Stable isotope ratios of O and Cl in perchlorate have been used recently to distinguish perchlorate of different origins. Isotopic ratios may also be useful for identifying the occurrence and extent of biodegradation of perchlorate in natural environments, information that is critical for assessing natural attenuation of this contaminant. For this approach to be useful, however, the extent of isotopic fractionation of both Cl and O by bacteria must be determined, and the influence of environmental variables on this process must be defined. During this laboratory study, the O and Cl isotope ratios of perchlorate were monitored as a function of degradation by two separate bacterial species (Azospira suillum JPLRND and Dechlorospirillum sp. FBR2) at both 10 °C and 22 °C with acetate as the electron donor. Perchlorate was completely degraded by both strains within 280 hr at 22 °C and 615 hr at 10 °C. Measured values of isotopic fractionation factors were ɛ18O = -36.6 to -29.0 ‰ and ɛ37Cl = -14.5 to - 11.5 ‰, and these showed no apparent systematic variation with either temperature or bacterial strain. One experiment using 18O-enriched water (δ18O = 200‰) gave results indistinguishable from those observed in isotopically normal water, indicating little or no isotopic exchange between perchlorate and water during biodegradation. The fractionation factor ratio ɛ18O/ɛ37Cl was nearly invariant in all experiments at 2.50 ± 0.04. These data indicate that isotopic analysis will be useful for documenting perchlorate biodegradation in soils and groundwater. The establishment of a microbial fractionation factor ratio (ɛ18O/ɛ37Cl) also has significance for forensic studies, as these data indicate that fractionation via biodegradation will not cause the reported mass-dependent Cl and O isotopic signatures of synthetic and natural perchlorate to overlap.

  1. Separate and Joint Associations of Occupational and Leisure-Time Sitting with Cardio-Metabolic Risk Factors in Working Adults: A Cross-Sectional Study

    PubMed Central

    Saidj, Madina; Jørgensen, Torben; Jacobsen, Rikke K.; Linneberg, Allan; Aadahl, Mette

    2013-01-01

    Background The workplace is a main setting for prolonged sitting for some occupational groups. Convincing evidence has recently accumulated on the detrimental cardio-metabolic health effects of leisure-time sitting. Yet, much less is known about occupational sitting, and the potential health risk attached compared to leisure-time sitting. Objective To explore the separate and joint associations of occupational and leisure-time sitting with cardio-metabolic risk factors in working adults. Methods All working adults (N = 2544) from the Health2006, a Danish population-based study, were included in this cross-sectional study. Participants reported hours of sitting during work, during leisure-time along with socio-demographic and behavioral characteristics, including physical activity. Cardio-metabolic risk factors (waist circumference, body mass index, body fat percentage, total cholesterol, HDL cholesterol, LDL cholesterol, triglycerides, insulin, hemoglobin A1c and plasma glucose) were measured. Associations were explored by linear regression for leisure-time, occupational, and overall sitting time. Results Statistically significant (p<.05) detrimental associations of leisure-time sitting were observed with all cardio-metabolic risk factors, except hemoglobin A1c and plasma glucose. Similarly, occupational sitting time was significantly detrimentally associated with HDL cholesterol, triglycerides, and insulin. For categories of sitting time, a joint adverse association of sitting much during both work-time and leisure-time was observed. Conclusion The associations of occupational sitting time with cardio-metabolic risk factors were fewer and weaker compared to leisure-time sitting. Yet, the joint associations of occupational and leisure-time sitting with cardio-metabolic risk factors were higher than the separate. Our findings amplify the need for further focus in this area prior to making assumptions about equivalent health risks across sedentary behaviors. To

  2. 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)

  3. Selective photoionisation of lutetium isotopes

    SciTech Connect

    D'yachkov, Aleksei B; Kovalevich, S K; Labozin, Valerii P; Mironov, Sergei M; Panchenko, Vladislav Ya; Firsov, Valerii A; Tsvetkov, G O; Shatalova, G G

    2012-10-31

    A three-stage laser photoionisation scheme intended for enriching the {sup 176}Lu isotope from natural lutetium was considered. An investigation was made of the hyperfine structure of the second excited state 5d6s7s {yields} {sup 4}D{sub 3/2} with an energy of 37194 cm{sup -1} and the autoionisation state with an energy of 53375 cm{sup -1} of the {sup 176}Lu and {sup 175}Lu isotopes. The total electron momentum of the autoionisation level and the constant A of hyperfine magnetic interaction were determined. Due to a small value of the isotopic shift between {sup 176}Lu and {sup 175}Lu, appreciable selectivity of their separation may be achieved with individual hyperfine structure components. The first tentative enrichment of the 176Lu isotope was performed to a concentration of 60 % - 70 %. (laser applications and other topics in quantum electronics)

  4. 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.

  5. Mass-independent isotope effects.

    PubMed

    Buchachenko, Anatoly L

    2013-02-28

    Three fundamental properties of atomic nuclei-mass, spin (and related magnetic moment), and volume-are the source of isotope effects. The mostly deserved and popular, with almost hundred-year history, is the mass-dependent isotope effect. The first mass-independent isotope effect which chemically discriminates isotopes by their nuclear spins and nuclear magnetic moments rather than by their masses was detected in 1976. It was named as the magnetic isotope effect because it is controlled by magnetic interaction, i.e., electron-nuclear hyperfine coupling in the paramagnetic species, the reaction intermediates. The effect follows from the universal physical property of chemical reactions to conserve angular momentum (spin) of electrons and nuclei. It is now detected for oxygen, silicon, sulfur, germanium, tin, mercury, magnesium, calcium, zinc, and uranium in a great variety of chemical and biochemical reactions including those of medical and ecological importance. Another mass-independent isotope effect was detected in 1983 as a deviation of isotopic distribution in reaction products from that which would be expected from the mass-dependent isotope effect. On the physical basis, it is in fact a mass-dependent effect, but it surprisingly results in isotope fractionation which is incompatible with that predicted by traditional mass-dependent effects. It is supposed to be a function of dynamic parameters of reaction and energy relaxation in excited states of products. The third, nuclear volume mass-independent isotope effect is detected in the high-resolution atomic and molecular spectra and in the extraction processes, but there are no unambiguous indications of its importance as an isotope fractionation factor in chemical reactions.

  6. Ultracapacitor separator

    DOEpatents

    Wei, Chang; Jerabek, Elihu Calvin; LeBlanc, Jr., Oliver Harris

    2001-03-06

    An ultracapacitor includes two solid, nonporous current collectors, two porous electrodes separating the collectors, a porous separator between the electrodes and an electrolyte occupying the pores in the electrodes and separator. The electrolyte is a polar aprotic organic solvent and a salt. The porous separator comprises a wet laid cellulosic material.

  7. Distinct Stromal Cell Factor Combinations Can Separately Control Hematopoietic Stem Cell Survival, Proliferation, and Self-Renewal

    PubMed Central

    Wohrer, Stefan; Knapp, David J.H.F.; Copley, Michael R.; Benz, Claudia; Kent, David G.; Rowe, Keegan; Babovic, Sonja; Mader, Heidi; Oostendorp, Robert A.J.; Eaves, Connie J.

    2014-01-01

    Summary Hematopoietic stem cells (HSCs) are identified by their ability to sustain prolonged blood cell production in vivo, although recent evidence suggests that durable self-renewal (DSR) is shared by HSC subtypes with distinct self-perpetuating differentiation programs. Net expansions of DSR-HSCs occur in vivo, but molecularly defined conditions that support similar responses in vitro are lacking. We hypothesized that this might require a combination of factors that differentially promote HSC viability, proliferation, and self-renewal. We now demonstrate that HSC survival and maintenance of DSR potential are variably supported by different Steel factor (SF)-containing cocktails with similar HSC-mitogenic activities. In addition, stromal cells produce other factors, including nerve growth factor and collagen 1, that can antagonize the apoptosis of initially quiescent adult HSCs and, in combination with SF and interleukin-11, produce >15-fold net expansions of DSR-HSCs ex vivo within 7 days. These findings point to the molecular basis of HSC control and expansion. PMID:24910437

  8. Laser Isotope Enrichment for Medical and Industrial Applications

    SciTech Connect

    Leonard Bond

    2006-07-01

    Laser Isotope Enrichment for Medical and Industrial Applications by Jeff Eerkens (University of Missouri), Jay Kunze (Idaho State University), and Leonard Bond (Idaho National Laboratory) The principal isotope enrichment business in the world is the enrichment of uranium for commercial power reactor fuels. However, there are a number of other needs for separated isotopes. Some examples are: 1) Pure isotopic targets for irradiation to produce medical radioisotopes. 2) Pure isotopes for semiconductors. 3) Low neutron capture isotopes for various uses in nuclear reactors. 4) Isotopes for industrial tracer/identification applications. Examples of interest to medicine are targets to produce radio-isotopes such as S-33, Mo-98, Mo-100, W-186, Sn-112; while for MRI diagnostics, the non-radioactive Xe-129 isotope is wanted. For super-semiconductor applications some desired industrial isotopes are Si-28, Ga-69, Ge-74, Se-80, Te-128, etc. An example of a low cross section isotope for use in reactors is Zn-68 as a corrosion inhibitor material in nuclear reactor primary systems. Neutron activation of Ar isotopes is of interest in industrial tracer and diagnostic applications (e.g. oil-logging). . In the past few years there has been a sufficient supply of isotopes in common demand, because of huge Russian stockpiles produced with old electromagnetic and centrifuge separators previously used for uranium enrichment. Production of specialized isotopes in the USA has been largely accomplished using old ”calutrons” (electromagnetic separators) at Oak Ridge National Laboratory. These methods of separating isotopes are rather energy inefficient. Use of lasers for isotope separation has been considered for many decades. None of the proposed methods have attained sufficient proof of principal status to be economically attractive to pursue commercially. Some of the authors have succeeded in separating sulfur isotopes using a rather new and different method, known as condensation

  9. 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.

  10. Magnesium isotope fractionation during continental weathering

    NASA Astrophysics Data System (ADS)

    Teng, F. Z.; Huang, K. J.; Li, W.; Liu, X. M.; Ma, L.

    2014-12-01

    Continental weathering links the atmosphere, hydrosphere and continents as it regulates the CO2 content of the atmosphere, shifts the composition of the continental crust from basaltic to andesitic, and ultimately controls the chemical composition of river waters and seawater. Magnesium is a water-soluble major element in the hydrosphere, continental crust and the mantle, and has three stable isotopes (24Mg, 25Mg and 26Mg). Studies of Mg isotopes during continental weathering may help to document the interactions between hydrosphere, crust and mantle. Previous studies have shown that the continental crust has a heterogeneous but on average heavier Mg isotopic composition than the mantle, whereas the hydrosphere is isotopically light. The complementary characteristics of Mg isotopic compositions between continental and hydrosphere have been attributed to continental weathering, with light Mg isotopes partitioned into water, leaving heavy Mg isotopes behind in the crustal residue. Here we summarize our studies of Mg isotope fractionation in four weathering profiles under various climate conditions. We show that large Mg isotope fractionation can occur during continental weathering. Although the weathered residue is usually enriched in heavier Mg isotopes than unaltered parent rocks, some heavily weathered products can be quite light in Mg isotopic composition. The complicated behaviors of Mg isotopes reflect different control factors during weathering such as parent rock lithology, primary mineral dissolution, secondary mineral formation, ion exchange, vegetation uptake etc. Though studies of natural samples can provide direct evidence on isotope fractionation, more well-controlled laboratory experiments on Mg isotope fractionation between fluids and minerals are needed in order to fully understand the behaviors of Mg isotopes during weathering, which ultimately lays the foundation for making Mg isotope geochemistry an important tool for studying different geological

  11. 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

  12. An estimate of the Germanium isotopic composition of the Ocean.

    NASA Astrophysics Data System (ADS)

    Galy, A.; Rouxel, O.; Mantoura, S.; Elderfield, H.; de La Rocha, C.

    2004-12-01

    Ge is a trace element in seawater whose biogeochemistry is dominated by its Si-like behaviour. Its residence time is poorly constrained but could be close to the mixing time of the ocean. In addition, hydrothermal vents are enriched in Ge (relative to Si) and this excess has been witnessed in the water column. Moreover, Si isotopic variations have been reported in the ocean, related to the precipitation of biogenic opal, while the Si residence time is slightly higher than the Ge residence time. Therefore, variations in the isotopic composition of dissolved Ge in the ocean are expected provided that at least one of the major input or output of Ge has a different isotopic composition. Given the low Ge concentration (around 40 picomol/kg) and the state-of-the art analytical facilities, a direct measurement of the isotopic composition of the seawater is barely conceivable. The major input of Ge into the ocean are the rivers and the hydrothermal vents, while the removal of Ge occurs through the precipitation of biogenic opal and the early diagenesis of passive margins. The mechanism of the later is, however, not well established but could be related to the precipitation of Fe-oxyhydroxide. So the measurement of marine authigenic minerals, biogenic silica and the comparison with an estimate of the bulk silicate Earth (BSE) composition will give some constraints on the Germanium isotopic composition of the ocean. A new technique for the precise and accurate determination of Ge stable isotope compositions has been developed and applied to silicate, sulfide, and biogenic material. The analyses were performed using a continuous flow hydride generation system coupled to a Nu Instrument MC-ICPMS. Samples have been purified through anion and cation exchange resins to separate Ge from matrix elements and potential interferences. Deep sea clays have a similar isotopic composition that MORBs or granites, suggesting that isotopic composition of the dissolved Ge in rivers might not

  13. Liquid-Liquid Phase Separation in a Dual Variable Domain Immunoglobulin Protein Solution: Effect of Formulation Factors and Protein-Protein Interactions.

    PubMed

    Raut, Ashlesha S; Kalonia, Devendra S

    2015-09-08

    Dual variable domain immunoglobulin proteins (DVD-Ig proteins) are large molecules (MW ∼ 200 kDa) with increased asymmetry because of their extended Y-like shape, which results in increased formulation challenges. Liquid-liquid phase separation (LLPS) of protein solutions into protein-rich and protein-poor phases reduces solution stability at intermediate concentrations and lower temperatures, and is a serious concern in formulation development as therapeutic proteins are generally stored at refrigerated conditions. In the current work, LLPS was studied for a DVD-Ig protein molecule as a function of solution conditions by measuring solution opalescence. LLPS of the protein was confirmed by equilibrium studies and by visually observing under microscope. The protein does not undergo any structural change after phase separation. Protein-protein interactions were measured by light scattering (kD) and Tcloud (temperature that marks the onset of phase separation). There is a good agreement between kD measured in dilute solution with Tcloud measured in the critical concentration range. Results indicate that the increased complexity of the molecule (with respect to size, shape, and charge distribution on the molecule) increases contribution of specific and nonspecific interactions in solution, which are affected by formulation factors, resulting in LLPS for DVD-Ig protein.

  14. Equilibrium clumped-isotope effects in doubly substituted isotopologues of ethane

    NASA Astrophysics Data System (ADS)

    Webb, Michael A.; Wang, Yimin; Braams, Bastiaan J.; Bowman, Joel M.; Miller, Thomas F.

    2017-01-01

    We combine path-integral Monte Carlo methods with a new intramolecular potential energy surface to quantify the equilibrium enrichment of doubly substituted ethane isotopologues due to clumped-isotope effects. Ethane represents the simplest molecule to simultaneously exhibit 13C-13C, 13C-D, and D-D clumped-isotope effects, and the analysis of corresponding signatures may provide useful geochemical and biogeochemical proxies of formation temperatures or reaction pathways. Utilizing path-integral statistical mechanics, we predict equilibrium fractionation factors that fully incorporate nuclear quantum effects, such as anharmonicity and rotational-vibrational coupling which are typically neglected by the widely used Urey model. The magnitude of the calculated fractionation factors for the doubly substituted ethane isotopologues indicates that isotopic clumping can be observed if rare-isotope substitutions are separated by up to three chemical bonds, but the diminishing strength of these effects suggests that enrichment at further separations will be negligible. The Urey model systematically underestimates enrichment due to 13C-D and D-D clumped-isotope effects in ethane, leading to small relative errors in the apparent equilibrium temperature, ranging from 5 K at 273.15 K to 30 K at 873.15 K. We additionally note that the rotameric dependence of isotopologue enrichment must be carefully considered when using the Urey model, whereas the path-integral calculations automatically account for such effects due to configurational sampling. These findings are of direct relevance to future clumped-isotope studies of ethane, as well as studies of 13C-13C, 13C-D, and D-D clumped-isotope effects in other hydrocarbons.

  15. Two different factors act separately or together to specify functionally distinct activities at a single transcriptional enhancer.

    PubMed Central

    DeFranco, D; Yamamoto, K R

    1986-01-01

    The expression of genes fused downstream of the Moloney murine sarcoma virus (MoMSV) long terminal repeat is stimulated by glucocorticoids. We mapped the glucocorticoid response element that conferred this hormonal regulation and found that it is a hormone-dependent transcriptional enhancer, designated Sg; it resides within DNA fragments that also carry a previously described enhancer element (B. Levinson, G. Khoury, G. Vande Woude, and P. Gruss, Nature [London] 295:568-572, 1982), here termed Sa, whose activity is independent of the hormone. Nuclease footprinting revealed that purified glucocorticoid receptor bound at multiple discrete sites within and at the borders of the tandemly repeated sequence motif that defines Sa. The Sa and Sg activities stimulated the apparent efficiency of cognate or heterologous promoter utilization, individually providing modest enhancement and in concert yielding higher levels of activity. A deletion mutant lacking most of the tandem repeat but retaining a single receptor footprint sequence lost Sa activity but still conferred Sg activity. The two enhancer components could also be distinguished physiologically: both were operative within cultured rat fibroblasts, but only Sg activity was detectable in rat exocrine pancreas cells. Therefore, the sequence determinants of Sa and Sg activity may be interdigitated, and when both components are active, the receptor and a putative Sa factor can apparently bind and act simultaneously. We concluded that MoMSV enhancer activity is effected by at least two distinct binding factors, suggesting that combinatorial regulation of promoter function can be mediated even from a single genetic element. Images PMID:3023887

  16. THEORETICAL AND EXPERIMENTAL ASPECTS OF ISOTOPIC FRACTIONATION.

    USGS Publications Warehouse

    O'Neil, James R.

    1986-01-01

    Essential to the interpretation of natural variations of light stable isotope ratios is knowledge of the magnitude and temperature dependence of isotopic fractionation factors between the common minerals and fluids. These fractionation factors are obtained in three ways: (1) Semi-empirical calculations using spectroscopic data and the methods of statistical mechanics. (2) Laboratory calibration studies. (3) Measurements of natural samples whose formation conditions are well-known or highly constrained. In this chapter methods (1) and (2) are evaluated and a review is given of the present state of knowledge of the theory of isotopic fractionation and the fraction that influence the isotopic properties of minerals.

  17. Zinc isotope fractionation during surface adsorption by bacteria

    NASA Astrophysics Data System (ADS)

    Kafantaris, F. A.; Borrok, D. M.

    2011-12-01

    The cycling and transport of zinc (Zn) in natural waters is partly controlled by its adsorption and uptake by bacterial communities. These reactions are reflected in changes in the ratios of stable Zn isotopes; however, the magnitudes and directions of these changes are largely unconstrained. In the current work, we attempt to define Zn isotope fractionation factors for bacteria-Zn interactions by performing adsorption experiments with representative Gram-positive (Bacillus subtilis) and Gram-negative (Pseudomonas mendocina) bacteria. Experiments included, (1) pH-dependent adsorption using differing bacteria:Zn ratios, (2) Zn loading at constant pH, and (3) kinetics and reversibility experiments. Results indicate that Zn adsorption is fully reversible for both bacterial species. Moreover, under the same experimental conditions both bacterial species adsorbed Zn to similar extents. Initial isotopic analysis (using a Nu Instruments MC-ICP-MS) demonstrates that, as the extent of adsorption increases, the heavier Zn isotopes are preferentially incorporated as bacterial-surface complexes. Under conditions of low bacteria:Zn ratio, the Δ66Znbacteria-solution was about 0.3% for both bacterial species. This separation factor is similar to that found in other studies involving the complexation of Zn with biologic or organic components. For example, the complexation of Zn with Purified Humic Acid (PHA) resulted in a Δ66ZnPHA-solution of +0.24% [1], and sorption of Zn onto two separate diatom species resulted in Δ66Znsolid-solution of +0.43% and +0.27%, respectively [2]. These results suggest that Zn complexation with functional groups common to bacteria and natural organic matter may be a process that universally incorporates the heavier Zn isotopes. Our current work is focused on quantifying Zn isotope fractionation during metabolic incorporation by separating this effect from surface adsorption reactions. [1] Jouvin et al., (2009) Environ. Sci. Technol., 43(15) 5747

  18. Isotope fractionation

    NASA Astrophysics Data System (ADS)

    Bell, Peter M.

    A rash of new controversy has emerged around the subject of mass-independent isotope fractionation effects, particularly in the case of the oxygen isotopes. To be sure, the controversy has been around for awhile, but it has been given new impetus by the results of a recent study by Mark H. Thiemens and John E. Heidenreich III of the University of California, San Diego (Science, March 4, 1983).Gustav Arrhenius has been trying to convince the planetary science community that chemical effects in isotope fractionation processes could explain observations in meteorites that appear to be outside of the traditionally understood mass-dependent fractionations (G. Arrhenius, J . L. McCrumb, and N. F. Friedman, Astrophys. Space Sci, 65, 297, 1974). Robert Clayton had made the basic observations of oxygen in carbonaceous chondrites that the slope of the δ17 versus δ18 line was 1 instead of the slope of ½ characteristic of terrestrial rocks and lunar samples (Ann. Rev. Nucl. Part. Sci., 28, 501, 1978). The mass-independent effects were ascribed to the apparent contribution of an ancient presolar system component of O16.

  19. Equilibrium Fe isotope fractionation between inorganic aqueous Fe(III) and the siderophore complex, Fe(III)-desferrioxamine B

    NASA Astrophysics Data System (ADS)

    Dideriksen, K.; Baker, J. A.; Stipp, S. L. S.

    2008-05-01

    In oxic oceans, most of the dissolved iron (Fe) exists as complexes with siderophore-like, strongly coordinating organic ligands. Thus, the isotope composition of the little amount of free inorganic Fe that is available for precipitation and preservation in the geological record may largely be controlled by isotope fractionation between the free and complexed iron. We have determined the equilibrium Fe isotope fractionation induced by organic ligand activity in experiments with solutions having co-existing inorganic Fe(III) species and siderophore complexes, Fe-desferrioxamine B (at pH 2). The two differently complexed Fe(III) pools were separated by addition of Na 2CO 3, which led to immediate precipitation of the inorganic Fe without causing significant dissociation of Fe-desferrioxamine complexes. Experiments using enriched 57Fe tracer showed that isotopic equilibration between the 57Fe-labelled inorganic species and the isotopically "normal" siderophore-bound Fe was rapid during the first few seconds and then became slower. Consequently, the data fitted poorly to first and second order reaction equations. However, with a two-stage reaction, the data fit perfectly with a first order equation for the slower stage, indicating that approximately 40% re-equilibration may take place during the separation of the two pools. To further test if the induced precipitation leads to experimental artefacts, the fractionation during precipitation of inorganic Fe was determined. Assuming a Rayleigh-type fractionation during precipitation, this experiment yielded an isotope fractionation factor of α56Fe solution-solid = 1.00027. Calculations based on these results indicate that isotopic re-equilibration is unlikely to significantly affect our determined equilibrium Fe isotope fractionation between inorganically and organically complexed Fe. To determine the equilibrium Fe isotope fractionation between inorganically and organically bound Fe(III), experiments with variable

  20. The nT1 translocation separates vulval regulatory elements from the egl-18 and elt-6 GATA factor genes.

    PubMed

    Koh, Kyunghee; Bernstein, Yelena; Sundaram, Meera V

    2004-03-01

    egl-18 and elt-6 are partially redundant, adjacent genes encoding GATA factors essential for viability, seam cell development, and vulval development in Caenorhabditis elegans. The nT1 reciprocal translocation causes a strong Vulvaless phenotype, and an nT1 breakpoint was previously mapped to the left arm of LGIV, where egl-18/elt-6 are located. Here we present evidence that the nT1 vulval phenotype is due to a disruption of egl-18/elt-6 function specifically in the vulva. egl-18 mutations do not complement nT1 for vulval defects, and the nT1 breakpoint on LGIV is located within approximately 800 bp upstream of a potential transcriptional start site of egl-18. In addition, we have identified a approximately 350-bp cis-regulatory region sufficient for vulval expression just upstream of the nT1 breakpoint. By examining the fusion state and division patterns of the cells in the developing vulva of nT1 mutants, we demonstrate that egl-18/elt-6 prevent fusion and promote cell proliferation at multiple steps of vulval development.

  1. The Impact of Surface Boundary Forcing on Simulation of the 1998 Summer Drought Over the US Midwest Using Factor Separation Technique

    NASA Technical Reports Server (NTRS)

    Stein, Uri; Fox-Rabinovitz, Michael

    1999-01-01

    The factor separation (FS) technique has been utilized to evaluate quantitatively the impact of surface boundary forcings on simulation of the 1988 summer drought over the Midwestern part of the U.S. The four surface boundary forcings used are: (1)Sea Surface Temperature (SST), (2) soil moisture, (3) snow cover, and (4) sea ice. The Goddard Earth Observing System(GEOS) General Circulation Model (GCM) is used to simulate the 1988 U.S. drought. A series of sixteen simulations are performed with climatological and real 1988 surface boundary conditions. The major single and mutual synergistic factors/impacts are analyzed. The results show that SST and soil moisture are the major single pro-drought factors. The couple synergistic effect of SST and soil moisture is the major anti-drought factor. The triple synergistic impact of SST, soil moisture, and snow cover is the strongest pro-drought impact and is, therefore, the main contributor to the generation of the drought. The impact of the snow cover and sea ice anomalies for June 1988 on the drought is significant only when combined with the SST and soil moisture anomalies.

  2. Carbon isotopic fractionation in the biosynthesis of bacterial fatty acids. Ozonolysis of unsaturated fatty acids as a means of determining the intramolecular distribution of carbon isotopes

    NASA Astrophysics Data System (ADS)

    Monson, K. David; Hayes, J. M.

    1982-02-01

    Methods for the determination of 13C abundances at individual olefinic carbon positions have been developed, tested, and shown to perform accurately. (1) The double bond is oxidized with ozone; (2) silver oxide is used to cleave the resulting ozonide quantitatively to carboxylic-acid fragments; (3) a modified Schmidt decarboxylation is used to produce CO 2 quantitatively from the carboxyl groups of the separated cleavage products; (4) the CO 2 is utilized for mass spectrometric analysis. The results of intramolecular isotopic analyses are combined with molecular-average isotopic compositions determined by total combustion in order to show that fatty acids biosynthesized by Escherichia coli grown aerobically with glucose as the sole carbon source and harvested at late log phase are depleted by approximately 3%. in 13C relative to the glucose. This fractionation arises in the formation of acetylcoenzyme A by pyruvate dehydrogenase and is localized at the carboxyl position in the acetyl-CoA product. The isotopic order in that two-carbon subunit is carried through the biosynthesis of fatty acids so that alternate positions in the fatty-acid chains are depleted in 13C by an amount equal to twice the molecular-average depletion. The kinetic isotope effect at C-2 for pyruvate dehydrogenase in vivo is shown to be approximately 2.3%. While it appears that no other fractionation mechanism has controlled the overall depletion of 13C in these fatty acids, a separate process responsible for control of isotopic abundances in the carboxyl groups has been identified and described elsewhere [Monson K.D. and Hayes J.M. (1980) J. Biol. Chem. 255, 11435-11441]. It is concluded that kinetic, rather than thermodynamic, factors have controlled isotopic distributions in these cells and that kinetic factors will be dominant in most biological reactions.

  3. Stable strontium mass dependent isotopic fractionation in authigenic continental barite

    NASA Astrophysics Data System (ADS)

    Griffith, E. M.; Widanagamage, I. H.; Scher, H. D.; Senko, J.

    2013-12-01

    The use of stable Sr-isotopic measurements (δ88Sr) of barite precipitates from terrestrial environments will be evaluated as a new geochemical proxy to identify mode of barite mineralization for use in earth science applications including understanding similar ancient barite deposits. Stable Sr-isotope measurements of barite and waters from three warm artesian springs in the continental United States where barite precipitates under a variety of conditions (e.g., temperatures, saturation states, microbial communities) will be presented. Initial results show a large range of fractionation factors during barite precipitation from aqueous solution between and within some of the field sites of >0.6 permil. The waters range from δ88Sr = -0.04 to +0.50 permil. The solid barite precipitates that have been separated from the bulk sediment using a modified sequential leaching procedure range from δ88Sr = -0.43 to +0.16 permil. Average 2σ for the isotopic analyses is 0.05 permil, similar to previously published estimates for error on this measurement by MC-ICPMS. Barite is a highly stable and widely-distributed mineral found in magmatic, metamorphic, and sedimentary rocks (of all ages), as well as in soils, aerosol dust, and extraterrestrial material. Establishing the controlling parameters of stable Sr-isotopic fractionation in barite is important as barite may be an ideal vehicle to address critical questions in the earth sciences, including early earth biogeochemistry.

  4. Working with Separation

    ERIC Educational Resources Information Center

    Krugman, Dorothy C.

    1971-01-01

    Discusses the role of the caseworker in providing support to children experiencing separation from their families and emphasizes the need to recognize that there are differences between those separation experiences dictated by the needs of children and those dictated by arbitrary or noncasework factors. (AJ)

  5. Lasers utilizing CO2 isotopes

    NASA Astrophysics Data System (ADS)

    Pechenin, Yu V.; Domanov, M. S.

    1980-08-01

    The lasing spectra and energy characteristics were investigated for lasers operating with the isotopes 12C16O2, 13C16O2, 12C18O2, and 12C16O18O. It was found that the output power of a laser utilizing the CO2 isotopes was determined by the content of a particular isotope in the carbon dioxide gas. For equal enrichments, all the isotopes investigated, with the exception of 12C16O18O, gave comparable output powers. The unsaturated gains were identical for the most intense transitions of the symmetric molecules; the gain was a factor of two less for the asymmetric molecule. The gain rose linearly with increasing enrichment. The ultimate specific power output, given by the product of the saturation power density and the gain, was practically independent of the enrichment.

  6. A Stochastic Method for Estimating the Effect of Isotopic Uncertainties in Spent Nuclear Fuel

    SciTech Connect

    DeHart, M.D.

    2001-08-24

    This report describes a novel approach developed at the Oak Ridge National Laboratory (ORNL) for the estimation of the uncertainty in the prediction of the neutron multiplication factor for spent nuclear fuel. This technique focuses on burnup credit, where credit is taken in criticality safety analysis for the reduced reactivity of fuel irradiated in and discharged from a reactor. Validation methods for burnup credit have attempted to separate the uncertainty associated with isotopic prediction methods from that of criticality eigenvalue calculations. Biases and uncertainties obtained in each step are combined additively. This approach, while conservative, can be excessive because of a physical assumptions employed. This report describes a statistical approach based on Monte Carlo sampling to directly estimate the total uncertainty in eigenvalue calculations resulting from uncertainties in isotopic predictions. The results can also be used to demonstrate the relative conservatism and statistical confidence associated with the method of additively combining uncertainties. This report does not make definitive conclusions on the magnitude of biases and uncertainties associated with isotopic predictions in a burnup credit analysis. These terms will vary depending on system design and the set of isotopic measurements used as a basis for estimating isotopic variances. Instead, the report describes a method that can be applied with a given design and set of isotopic data for estimating design-specific biases and uncertainties.

  7. Chiral Separations

    NASA Astrophysics Data System (ADS)

    Stalcup, A. M.

    2010-07-01

    The main goal of this review is to provide a brief overview of chiral separations to researchers who are versed in the area of analytical separations but unfamiliar with chiral separations. To researchers who are not familiar with this area, there is currently a bewildering array of commercially available chiral columns, chiral derivatizing reagents, and chiral selectors for approaches that span the range of analytical separation platforms (e.g., high-performance liquid chromatography, gas chromatography, supercritical-fluid chromatography, and capillary electrophoresis). This review begins with a brief discussion of chirality before examining the general strategies and commonalities among all of the chiral separation techniques. Rather than exhaustively listing all the chiral selectors and applications, this review highlights significant issues and differences between chiral and achiral separations, providing salient examples from specific classes of chiral selectors where appropriate.

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

    NASA Astrophysics Data System (ADS)

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

    1995-01-01

    Less than 15 min are required for the determination of δ13CPDB with a precision of 0.2‰ (1σ, 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 δ 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 sample 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 <1‰.

  9. 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.

  10. Water separator

    NASA Technical Reports Server (NTRS)

    Dunn, W. F.; Austin, I. G. (Inventor)

    1964-01-01

    An apparatus for separating liquids from gases or gaseous fluids is described. Features of the apparatus include: (1) the collection and removal of the moisture in the fluid is not dependent upon, or affected by gravity; (2) all the collected water is cyclically drained from the apparatus irrespective of the attitude of the separator; and (3) a fluid actuator is utilized to remove the collected water from the separator.

  11. High-precision measurements of seawater Pb isotope compositions by double spike thermal ionization mass spectrometry.

    PubMed

    Paul, Maxence; Bridgestock, Luke; Rehkämper, Mark; van DeFlierdt, Tina; Weiss, Dominik

    2015-03-10

    A new method for the determination of seawater Pb isotope compositions and concentrations was developed, which combines and optimizes previously published protocols for the separation and isotopic analysis of this element. For isotopic analysis, the procedure involves initial separation of Pb from 1 to 2L of seawater by co-precipitation with Mg hydroxide and further purification by a two stage anion exchange procedure. The Pb isotope measurements are subsequently carried out by thermal ionization mass spectrometry using a (207)Pb-(204)Pb double spike for correction of instrumental mass fractionation. These methods are associated with a total procedural Pb blank of 28±21 pg (1sd) and typical Pb recoveries of 40-60%. The Pb concentrations are determined by isotope dilution (ID) on 50 mL of seawater, using a simplified version of above methods. Analyses of multiple aliquots of six seawater samples yield a reproducibility of about ±1 to ±10% (1sd) for Pb concentrations of between 7 and 50 pmol/kg, where precision was primarily limited by the uncertainty of the blank correction (12±4 pg; 1sd). For the Pb isotope analyses, typical reproducibilities (±2sd) of 700-1500 ppm and 1000-2000 ppm were achieved for (207)Pb/(206)Pb, (208)Pb/(206)Pb and (206)Pb/(204)Pb, (207)Pb/(204)Pb, (208)Pb/(204)Pb, respectively. These results are superior to literature data that were obtained using plasma source mass spectrometry and they are at least a factor of five more precise for ratios involving the minor (204)Pb isotope. Both Pb concentration and isotope data, furthermore, show good agreement with published results for two seawater intercomparison samples of the GEOTRACES program. Finally, the new methods were applied to a seawater depth profile from the eastern South Atlantic. Both Pb contents and isotope compositions display a smooth evolution with depth, and no obvious outliers. Compared to previous Pb isotope data for seawater, the (206)Pb/(204)Pb ratios are well correlated

  12. Ultrasensitive detection of radioactive cesium isotopes using a magneto-optical trap.

    SciTech Connect

    Di Rosa, M. D.; Crane, S. G.; Kitten, J. J.; Taylor, W. A.; Vieira, D. J.; Zhao, X.

    2002-01-01

    We report the first magneto-optical trapping of mdioactive {sup 135}Cs and {sup 137}Cs and a promising means for detecting these isotopes to ullrasensilive lcvels by a system coupling the magneto-optical trap (MOT) to a mass separator. The mass separator efficiently delivers a 20 kV ion beam of either isotope into a quartzcube MOT cell having in one corner a small-diameter Zr foil, on which the ion beam is focused and into which the ions are implantetl. Inductive heating of thc foil releases {approx}45% of the implanted atoms into a MOT that uses large diameter beams and a dry-film coating to capture 3% of the released vapor. MOT fluorescence signals were found to increasc linearly with the number of foil-implanted atoms over a range of 10{sup 4} to 10{sup 7} in trapped-atom number. The measured slope of MOT signal versus number implanted was equal in the case each isotope to within 4%, signifying our ability to measure {sup 137}Cs/{sup 135}Cs ratios to within 4%. The isotopic selectivities of the mass separator and MOT combine to suppress interfering signal from {sup 133}Cs by a factor of greater than 5 x 10{sup 12} in the case of detecting {sup 135}Cs or {sup 137}Cs. Our present sample detection sensitivity is one million atoms.

  13. Numerical simulation of the gravitational separation in the stratosphere

    NASA Astrophysics Data System (ADS)

    Sugawara, S.; Ishidoya, S.; Morimoto, S.; Aoki, S.; Nakazawa, T.; Honda, H.; Murayama, S.

    2012-12-01

    It has been shown that the gravitational separation effect in the stratosphere can be observable from the measurements of N2, O2 and Ar isotopic ratios and Ar/N2 ratio. The gravitational separation has a possibility to be a new tracer of stratospheric circulation. In this study, theoretical simulations were performed to validate an existence of the gravitational separation in the stratosphere, as well as to evaluate the magnitude of the isotopic discrimination of the atmospheric major components driven by molecular diffusion process. The 2-dimensional model of the middle atmosphere (SOCRATES) developed by NCAR was used to evaluate the gravitational separation in the stratosphere. This model originally includes mass transport processes caused by molecular diffusion to take into account only above the mesosphere, since the molecular diffusion effect has been thought to be negligibly small in the stratosphere, compared with the eddy diffusion effect. In this study, we simply lowered its vertical domain to the tropopause for the calculation of molecular diffusion. We assumed the thermal diffusion factor to be zero, since the thermal diffusion effect would be of no importance in the stratosphere. We simulated the height-latitude distributions of 44CO2 and 45CO2 concentrations, and then calculated the isotopic ratio as a δ value (in per meg). As a result, it is concluded that the magnitude of the gravitational separation in the stratosphere will be significant enough to be detected by recent isotopic measurements. To examine how the CO2 age and the δ value are influenced by changes in the stratospheric circulation, we made numerical simulations under the condition that the meridional mass transport is arbitrarily accelerated on the supposition that the Brewer-Dobson circulation (BDC) is enhanced due to global warming. The relationships between the two variables under the enhanced-BDC condition are clearly different from those under the normal condition, indicating that

  14. Numerical investigation with a coupled single-column lake-atmosphere model: using the Alpert-Stein factor separation methodology to assess the sensitivity of surface interactions

    NASA Astrophysics Data System (ADS)

    Goyette, Stéphane

    2016-06-01

    A coupled single-column atmosphere-lake model, along with the Stein-Alpert factor separation methodology, is used to explore some of the non-linear interactions in the vertical dimension between the lower atmosphere and the deep-Lake Geneva, Switzerland, during three selected periods in 1990. The first from the end of April to the end of May when Lake Geneva was building its stratification, the second from mid-August to mid-September during stable stratification, and the third from the end of November to the end of December during destratification. It is recognized that the large thermal inertia of Lake Geneva reduces the surface annual and diurnal temperature variations for neighbouring regions. However, the question of how the open water and the overlying atmosphere interact and which of these "factors" has the most influence needs much attention. The sole presence of the lake is shown to be a major feature with regard to the surface energy budget components whose contributions counteract those of the lower atmosphere, thus supporting the fact that Lake Geneva acts as a damping factor to the regional climate system. It is also shown that not only did the presence of the lake and the overlying atmosphere independently modulate the surface energy budget, but also the synergistic nonlinear interaction among them, either positive or negative, was often found non-negligible. Moreover, some processes may turn out to be important on short time scales while being negligible on the long term.

  15. Set-up of large laboratory-scale chromatographic separations of poly(ethylene glycol) derivatives of the growth hormone-releasing factor 1-29 analogue.

    PubMed

    Piquet, G; Gatti, M; Barbero, L; Traversa, S; Caccia, P; Esposito, P

    2002-01-25

    In this paper we report the scale-up of the purification of poly(ethylene glycol) (PEG) derivatives of the growth hormone-releasing factor 1-29, from laboratory scale (100 mg of bulk starting material) to larger scale (3 g of bulk), through the use of a cation-exchange TSK-SP-5PW chromatographic column. A one-step purification process capable of purifying large amounts of mono-PEGylated GRF species from the crude reaction mixture was developed. A simple, straightforward stepwise gradient elution separation was developed at laboratory scale and then scaled up with a larger column packed with a chromatographic resin with the same chemistry which maintained the laboratory-scale separation profile. Active material recovery and material purity remained constant through the scale-up from the 13-microm stationary phase to the 25-microm larger column. Overall, the gram GRF equivalent/batch process scale showed to be quite reproducible, and could be considered as a good platform for scale up to production scale.

  16. A separable domain of the p150 subunit of human chromatin assembly factor-1 promotes protein and chromosome associations with nucleoli

    PubMed Central

    Smith, Corey L.; Matheson, Timothy D.; Trombly, Daniel J.; Sun, Xiaoming; Campeau, Eric; Han, Xuemei; Yates, John R.; Kaufman, Paul D.

    2014-01-01

    Chromatin assembly factor-1 (CAF-1) is a three-subunit protein complex conserved throughout eukaryotes that deposits histones during DNA synthesis. Here we present a novel role for the human p150 subunit in regulating nucleolar macromolecular interactions. Acute depletion of p150 causes redistribution of multiple nucleolar proteins and reduces nucleolar association with several repetitive element–containing loci. Of note, a point mutation in a SUMO-interacting motif (SIM) within p150 abolishes nucleolar associations, whereas PCNA or HP1 interaction sites within p150 are not required for these interactions. In addition, acute depletion of SUMO-2 or the SUMO E2 ligase Ubc9 reduces α-satellite DNA association with nucleoli. The nucleolar functions of p150 are separable from its interactions with the other subunits of the CAF-1 complex because an N-terminal fragment of p150 (p150N) that cannot interact with other CAF-1 subunits is sufficient for maintaining nucleolar chromosome and protein associations. Therefore these data define novel functions for a separable domain of the p150 protein, regulating protein and DNA interactions at the nucleolus. PMID:25057015

  17. 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.

  18. 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).

  19. Fractionation of Cu and Zn isotopes during adsorption onto amorphous Fe(III) oxyhydroxide: Experimental mixing of acid rock drainage and ambient river water

    NASA Astrophysics Data System (ADS)

    Balistrieri, Laurie S.; Borrok, David M.; Wanty, Richard B.; Ridley, W. Ian

    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 (αsoln-solid) are 0.99927 ± 0.00008 for Cu and 0.99948 ± 0.00004 for Zn or, alternately, the separation factors (Δsoln-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).

  20. Quantitative Microbial Ecology through Stable Isotope Probing

    PubMed Central

    Mau, Rebecca L.; Schwartz, Egbert; Caporaso, J. Gregory; Dijkstra, Paul; van Gestel, Natasja; Koch, Benjamin J.; Liu, Cindy M.; McHugh, Theresa A.; Marks, Jane C.; Morrissey, Ember M.; Price, Lance B.

    2015-01-01

    Bacteria grow and transform elements at different rates, and as yet, quantifying this variation in the environment is difficult. Determining isotope enrichment with fine taxonomic resolution after exposure to isotope tracers could help, but there are few suitable techniques. We propose a modification to stable isotope probing (SIP) that enables the isotopic composition of DNA from individual bacterial taxa after exposure to isotope tracers to be determined. In our modification, after isopycnic centrifugation, DNA is collected in multiple density fractions, and each fraction is sequenced separately. Taxon-specific density curves are produced for labeled and nonlabeled treatments, from which the shift in density for each individual taxon in response to isotope labeling is calculated. Expressing each taxon's density shift relative to that taxon's density measured without isotope enrichment accounts for the influence of nucleic acid composition on density and isolates the influence of isotope tracer assimilation. The shift in density translates quantitatively to isotopic enrichment. Because this revision to SIP allows quantitative measurements of isotope enrichment, we propose to call it quantitative stable isotope probing (qSIP). We demonstrated qSIP using soil incubations, in which soil bacteria exhibited strong taxonomic variations in 18O and 13C composition after exposure to [18O]water or [13C]glucose. The addition of glucose increased the assimilation of 18O into DNA from [18O]water. However, the increase in 18O assimilation was greater than expected based on utilization of glucose-derived carbon alone, because the addition of glucose indirectly stimulated bacteria to utilize other substrates for growth. This example illustrates the benefit of a quantitative approach to stable isotope probing. PMID:26296731