Provenance and sedimentary environments of the Proterozoic São Roque Group, SE-Brazil: Contributions from petrography, geochemistry and Sm-Nd isotopic systematics of metasedimentary rocks

NASA Astrophysics Data System (ADS)

Henrique-Pinto, R.; Janasi, V. A.; Tassinari, C. C. G.; Carvalho, B. B.; Cioffi, C. R.; Stríkis, N. M.

2015-11-01

The Proterozoic metasedimentary sequences exposed in the São Roque Domain (Apiaí Terrane, Ribeira Belt, southeast Brazil) consist of metasandstones and meta-felspathic wackes with some volcanic layers of within-plate geochemical signature (Boturuna Formation), a passive margin turbidite sequence of metawackes and metamudstones (Piragibu Formation), and volcano-sedimentary sequences with MORB-like basalts (Serra do Itaberaba Group; Pirapora do Bom Jesus Formation). A combination of zircon provenance studies in metasandstones, whole-rock geochemistry and Sm-Nd isotopic systematics in metamudstones was used to understand the provenance and tectonic significance of these sequences, and their implications to the evolution of the Precambrian crust in the region. Whole-rock geochemistry of metamudstones, dominantly from the Piragibu Formation, points to largely granitic sources (as indicated for instance by LREE-rich moderately fractionated REE patterns and subtle negative Eu anomalies) with some mafic contribution (responding for higher contents of Fe2O3, MgO, V, and Cr) and were subject to moderate weathering (CIA - 51 to 85). Sm-Nd isotope data show three main peaks of Nd TDM ages at ca. 1.9, 2.1 and 2.4 Ga; the younger ages define an upper limit for the deposition of the unit, and reflect greater contributions from sources younger than the >2.1 Ga basement. The coincident age peaks of Nd TDM and U-Pb detrital zircons at 2.1-2.2 Ga and 2.4-2.5 Ga, combined with the possible presence of a small amount of zircons derived from mafic (gabbroid) sources with the same ages, as indicated by a parallel LA-ICPMS U-Pb dating study in metapsammites, are suggestive that these were major periods of crustal growth in the sources involving not only crust recycling but also some juvenile addition. A derivation from similar older Proterozoic sources deposited in a passive margin basin is consistent with the main sedimentary sequences in the São Roque Domain being broadly coeval and in part laterally continuous. The coincident age, Sm-Nd isotope signature and geographic proximity make the exposures of basement orthogneisses in the Apiaí Terrane candidates for source material to the São Roque Domain. Additional sources with younger Nd TDM could be juvenile 2.2 Ga basement from the southern portion of the São Francisco Craton and its marginal belts (e.g., Mineiro Belt and Juiz de Fora Complex).

The efficacy of facial skin cancer treatment with high-energy pulsed neodymium and Nd:YAG lasers.

PubMed

Moskalik, Konstantin; Kozlov, Alexander; Demin, Eugeny; Boiko, Ernest

2009-04-01

The aim of this study was to assess the curative and cosmetic efficacy of treatment for facial skin cancer using neodymium laser irradiation. Due to the complex anatomy of the area, therapy for facial skin cancer is difficult. Laser irradiation was used for the treatment of 3461 patients with 3624 facial skin cancer lesions of stages T(1-2)N(0)M(0:) 3346 basal cell skin cancers, 188 limited basal cell skin cancer recurrences, and 90 squamous cell skin cancers. Pulsed neodymium (Nd) and Nd:YAG lasers were used as the energy sources. The patients were followed-up from 3 mo to 5 y or more. Patients with basal cell skin cancer treated by irradiation with the Nd laser developed recurrences in 1.8% of cases, and patients treated with the Nd:YAG laser had a recurrence rate of 2.5%. Recurrences following treatment for basal cell skin cancer, and those of squamous cell skin cancer, after irradiation with the Nd laser appeared in 3.7% and 4.4% of patients, respectively. Overall, the frequency of facial skin cancer recurrences after treatment with laser irradiation was 2.1% of all the irradiated tumors. Neodymium laser irradiation is an effective method to treat facial skin cancer of stages T(1-2)N(0)M(0), and results in acceptable cosmetic results.

Geochemical Constrains on MORB Composition and Magma Sources at East Pacific Rise Between 1°S and 2°S

NASA Astrophysics Data System (ADS)

Zhang, Wei; Zeng, Zhigang; Cui, Lukai; Yin, Xuebo

2018-04-01

The East Pacific Rise (EPR) is a typical fast spreading ridge. To gain a better understanding of the magmatism under ridges, Mid Ocean Ridge Basalts (MORBs) with remarkably heterogeneous compositions are obtained from (EPR) 1°-2°S and multielement geochemical and radioisotope analyses are conducted. Results show that these MORBs have wide variation ranges in trace element concentrations and isotopic ratios. Sample 07 has low concentrations of incompatible elements, and very low 87Sr/86Sr, and high 143Nd/144Nd from 0.70213 to 0.702289 and 0.513234 to 0.513289, respectively. However, other samples show enrichment in incompatible elements to varying degrees, and medium values of 87Sr/86Sr and 143Nd/144Nd from 0.702440 to 0.702680 and 0.513086 to 0.513200, respectively. This study proposes that one depleted source and two enriched sources contribute to the formation of MORBs from EPR 1°-2°S. Samples 02 and 10 are formed by mixing between one enriched source and one depleted source, while sample 07 is crystallized from the depleted source with no mixing process involved. However, the formation of samples 06 and 11 are different, and thus further research is required to determine genesis.

Mantle heterogeneity and crustal recycling in Archean granite-greenstone belts - Evidence from Nd isotopes and trace elements in the Rainy Lake area, Superior Province, Ontario, Canada

NASA Technical Reports Server (NTRS)

Shirey, Steven B.; Hanson, Gilbert N.

1986-01-01

Crustal evolution in the Rainy Lake area, Ontario is studied in terms of geochemical characteristics. The Nd isotope data are examined for heterogeneity of the Archean mantle, and the Sm/Nd depletion of the mantle is analyzed. The Nd isotope systematics of individual rock suites is investigated in order to understand the difference between crust and mantle sources; the precursors and petrogenetic processes are discussed. The correlation between SiO2 content and Nd values is considered. Rapid recycling of crustal components, which were previously derived from depleted mantle sources, is suggested based on the similarity of the initial Nd isotopic composition for both mantle-derived and crustally-derived rocks.

Microstructure evolution and coercivity enhancement in Nd-Fe-B thin films diffusion-processed by R-Al alloys (R=Nd, Pr)

NASA Astrophysics Data System (ADS)

Xie, Yigao; Yang, Yang; Zhang, Tongbo; Fu, Yanqing; Jiang, Qingzheng; Ma, Shengcan; Zhong, Zhenchen; Cui, Weibin; Wang, Qiang

2018-05-01

Diffusion process by Nd-Al and Pr-Al alloys was compared and investigated in Nd-Fe-B thin films. Enhanced coercivity 2.06T and good squareness was obtained by using Pr85Al15 and Nd85Al15 alloys as diffusion sources. But the coercivity of diffusion-processed thin films by Pr70Al30 and Pr55Al45 alloys decreased to 2.04T and 1.82T. High ambient coercivity of 2.26T was achieved in diffusion-processed thin film by Nd70Al30 leading to an improved coercivity thermal stability because Nd2Fe14B grains were enveloped by Nd-rich phase as seen by transmission electron microscopy Nd-loss image. Meanwhile, microstructure-dependent parameters α and Neff were improved. However, high content of Al in diffusion-processed thin film by Nd55Al45 lead to degraded texture and coercivity.

Study of visible luminescence spectra from Nd3+ doped TPO glass upon 808 nm excitation

NASA Astrophysics Data System (ADS)

Azam, Mohd; Rai, Vineet Kumar

2018-05-01

The Nd3+ doped TPO glasses have been prepared by melting and quenching method using the high temperature electric furnace. The upconversion (UC) spectra of Nd3+ doped TPO glasses at different concentration of rare ions have been recorded in the 400-700 nm wavelength range upon 808 nm laser excitation source. In the UC emission process, there are four bands centered at ˜495 nm, 546 nm, 602 nm and 653 nm respectively in the visible range were observed. But the green and red bands centered at˜546 nm and ˜653 nm corresponding to the 4G7/2 → 4I9/2 and 4G7/2 → 4I13/2 transitions respectively have been observed as the strong bands. The UC emission mechanism was observed as two photon process. The material can be used as a good NIR to visible upconverter and non-colour tunable display.

Strontium and neodymium isotopes in hot springs on the East Pacific Rise and Guaymas Basin

NASA Technical Reports Server (NTRS)

Piepgras, D. J.; Wasserburg, G. J.

1985-01-01

Solutions collected from 21 deg N, East Pacific Rise (Epr) and Guaymas Basin, Gulf of California, are analyzed for Nd isotopic composition and Sm and Nd concentrations. The results indicate extensive but not complete isotopic exchange with Sr in the depleted oceanic crust and that Sr concentrations in these solutions are buffered. In contrast, the Nd data exhibit a wide range in isotopic composition and concentration between vents. Many samples show substantial contributions from MORB, but all have isotopic compositions below MORB, in spite of enrichments in Nd up to 100 times seawater. It is shown that the fluids must exchange Nd with a sedimentary reservoir having an isotopic composition less than Pacific seawater. Low-temperature reactions with metalliferous sediments on the flanks of the EPR may provide such a source. Using a simple box method, estimates of the hydrothermal fluxes of Nd are compared to fluxes which are necessary to maintain a radiogenic isotopic composition of about -3 in the Pacific against the influx of Antarctic waters. It is concluded that erosion from island arcs is the main source of radiogenic Nd in the Pacific.

Hadean silicate differentiation revealed by anomalous 142Nd in the Réunion hotspot source

NASA Astrophysics Data System (ADS)

Peters, B. J.; Carlson, R.; Day, J. M.; Horan, M.

2017-12-01

Geochemical and geophysical data show that volcanic hotspots can tap ancient domains sequestered in Earth's deep mantle. Evidence from stable and long-lived radiogenic isotope systems has demonstrated that many of these domains result from tectonic and differentiation processes that occurred more than two billion years ago. Recent advances in the analysis of short-lived radiogenic isotopes have further shown that some hotspot sources preserve evidence for metal-silicate differentiation occurring within the first one percent of Earth's history. Despite these discoveries, efforts to detect variability in the lithophile 146Sm-142Nd (t1/2 = 103 Ma) system in Phanerozoic hotspot lavas have not yet detected significant global variation. We report 142Nd/144Nd ratios in Réunion Island basalts that are statistically distinct from the terrestrial Nd standard ranging to both higher and lower 142Nd/144Nd. Variations in 142Nd/144Nd, which total nearly 15 ppm on Réunion, are correlated with 3He/4He among both anomalous and non-anomalous samples. Such behavior implies that there were analogous changes in Sm/Nd and (U+Th)/3He that occurred during a Hadean silicate differentiation event and were not completely overprinted by the depleted mantle. Variations in the 142Nd-143Nd compositions of Réunion basalts can be explained by a single Hadean melting event producing enriched and depleted domains that partially re-mixed after 146Sm was no longer extant. Assuming differentiation occurred at pressures where perovskite is stable, anomalies of the magnitude observed in Réunion basalts require melting of at least 50% across a wide depth range, and up to 90% for melting at pressures near those of the deepest mantle. Models with best fits to Nd isotope data suggest this differentiation occurred around 4.40 Ga and mixing occurred after 4 Ga. This two-stage differentiation process nearly erased the ancient, anomalous 142Nd composition of the Réunion source and produced the relatively invariant 143Nd signature that is a hallmark of Réunion hotspot lavas. Given growing evidence that the Réunion hotspot source represents an unusually ancient, primitive mantle domain, these new data argue that Réunion is a critical source of information regarding the formation and preservation of ancient heterogeneities in Earth's deep interior.

Evolution of Nd and Pb isotopes in Central Pacific seawater from ferromanganese crusts

USGS Publications Warehouse

Ling, H.F.; Burton, K.W.; O'Nions, R. K.; Kamber, B.S.; Von Blanckenburg, F.; Gibb, A.J.; Hein, J.R.

1997-01-01

Hydrogenetic ferromanganese crusts incorporate elements from ambient seawater during their growth on seamounts. By analysing Nd, Pb and Be isotope profiles within crusts it is possible to reconstruct seawater tracer histories. Depth profiles of 10Be/9Be ratios in three Pacific ferromanganese crusts have been used to obtain growth rates which are between 1.4 and 3.8 mm/Ma. Nd and Pb isotopes provide intact records of isotopic variations in Pacific seawater over the last 20 Ma or more. There were only small changes in Pb isotope composition in the last 20 Ma. This indicates a constant Pb composition for the erosional sources and suggests further that erosional Nd inputs may have been uniform too. ??ND values vary considerably with time and most probably reflect changes in ocean circulation. The ??ND values of the crusts not only vary as a function of age but also as a function of water depth. From 25 to 0 Ma, crust VA13/2 from 4.8 km water depth has a similar pattern of ??ND variation to the two shallower crusts from 1.8 and 2.3 km, but about 1.0 to 1.5 units more negative. This suggests that ??ND stratification in Pacific seawater, as demonstrated for the present day, has been maintained for at least 20 Ma. Each crust shows a decrease in ??ND from 3-5 Ma to the present, which is interpreted in terms of an increase in the NADW component present in the Pacific. From 10 to 3-5 Ma ago the crusts show an increase in ??ND. This suggests a decreasing role for a deep water source with ??ND less than circum-Pacific sources. In this regard the Panamanian gateway restriction from ???10 Ma with final closure at 3-5 Ma may have played an important role in reducing access of Atlantic-derived Nd to the Pacific.

Reconstruction of the North Atlantic end-member of the Atlantic Meridional Overturning Circulation over glacial-interglacial cycles

NASA Astrophysics Data System (ADS)

Kim, J.; Seguí, M. J.; Knudson, K. P.; Yehudai, M.; Goldstein, S. L.; Pena, L. D.; Basak, C.; Ferretti, P.

2017-12-01

North Atlantic Deep Water (NADW) represents the major water mass that drives the Atlantic Meridional Ocean Circulation (AMOC), which undergoes substantial reorganization with changing climate. In order to understand its impact on ocean circulation and climate through time, it is necessary to constrain its composition. We report Nd isotope ratios of Fe-Mn oxide encrusted foraminifera and fish debris from DSDP Site 607 (41.00N 32.96W, 3427m), in the present-day core of NADW, and ODP 1063 (33.68N 57.62W, 4585m), on the deep abyssal plain at the interface between NADW and Antarctic Bottom Water. We provide a new North Atlantic paleocirculation record covering 2 Ma. At Site 607 interglacial ɛNd-values are consistently similar to present-day NADW (ɛNd -13.5), with median ɛNd-values of -14.3 in the Early Pleistocene and -13.8 in the Late Pleistocene. Glacial ɛNd-values are higher by 1 ɛNd-unit in the Early Pleistocene, and 1.5-2 ɛNd-units in the Late Pleistocene. Site 1063 shows much greater variability, with ɛNd ranging from -10 to -26. We interpret the North Atlantic AMOC source as represented by the Site 607 interglacial ɛNd-values, which has remained nearly stable throughout the entire period. The higher glacial ɛNd-values reflect incursions of some southern-sourced waters to Site 607, which is supported by coeval shifts to lower benthic foraminiferal d13C. In contrast, the Site 1063 ɛNd-values do not appear to reflect the AMOC end-member, and likely reflects local effects from a bottom source. A period of greatly disrupted ocean circulation marks 950-850 Ma, which may have been triggered by enhanced ice growth in the Northern Hemisphere that began around 1.2 Ma, as suggested by possible input events of Nd from the surrounding cratons into the North Atlantic observed in Site 607. Interglacial AMOC only recovers to the previously observed vigor over 200 ka following the disruption, whereas further intensified SSW incursion into the deep North Atlantic come to characterize the mid-late Pleistocene glacial intervals.

On the origin of cratonic `high-mu' isotopic signatures

NASA Astrophysics Data System (ADS)

Reimink, J. R.; Carlson, R.; Shirey, S. B.; Pearson, D. G.; Kamber, B. S.

2017-12-01

Some Archean cratons (i.e. Slave, Wyoming) contain Neoarchean granitoids with initial Pb isotopic compositions indicative of derivation from sources characterized by high time-integrated U/Pb ratios (high-mu [1]). Single-stage high-m precursor source reservoir separation from the depleted mantle occurred no later than 3.9 Ga [2]. However, multi-stage separation could have occurred in the Hadean, suggesting that recycling or reworking of Eoarchean/Hadean crust played a significant role in the generation of Neoarchean granitic crust in many cratons. The Sm-Nd system is similar to the U-Pb system in that it has a short-lived parent-daughter pair (146Sm-142Nd) that is sensitive to very early differentiation events, as well as a long-lived parent-daughter pair (147Sm-143Nd) that is sensitive to differentiation throughout all of Earth history. The 103 Ma half-life of 146Sm makes it sensitive only to Sm/Nd fractionation that occurred in the Hadean, providing a useful tracker for very early differentiation events. Indeed, evidence for Neoarchean remelting of ancient crust in another craton has come from analyses of the paired Sm-Nd isotope systems from the Hudson Bay terrane of the northeastern Superior Province. These results indicate that the source of 2.7 Ga Hudson Bay terrane granitoids was Hadean mafic crust, and not Eoarchean felsic crust [3]. Here, we present new data from Neoarchean granites located in the Slave and Wyoming cratons, along with modeling of the dual paired-isotope systems of U-Pb and Sm-Nd to achieve a tighter constraint on the composition of the precursors and the timing of their melting. Combining our newly collected 142Nd data with the high-m signature of these Neoarchean rocks, we evaluate precursor source separation ages along with the source Sm/Nd and U/Pb compositions. In the simplest end-member scenarios, use of the 142Nd system allows us to test whether the cratonic high-mu signature was created by melting of Hadean mafic crust or Eoarchean felsic crust. Differences between these models have major implications for the longevity of mafic crust on the ancient Earth as well as the growth rate and recycling history of the continents. [1] Oversby, 1978, EPSL; [2] Kamber et al., 2003, CMP; [3] O'Neil and Carlson, 2017; Science

Increasing influence of exotic terranes as sources of shales from the Sevier and Taconic Foreland basins : Evidence from Nd isotopes

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

Samson, S.D.; Andersen, C.B.

1994-03-01

The influence of outboard tectonostratigraphic terranes as a source of sediment to Ordovician foreland basins is unknown. To determine if there were changes in provenance, or changes in the importance of a given source region, the authors have analyzed shales from two foreland basins, the Tactonic Foreland basin of central New York and the Sevier Foreland basin of Tennessee, for their Nd isotopic compositions. Shales from the Taconic basin include those from the lower portion of Utica shale, Corynoides americanus graptolite Zone, and the uppermost portion of the Utica shale, including the Geniculograptus pygmaeus graptolite Zone. Initial [epsilon][sub Nd] valuesmore » for the oldest Taconic basin shales are [minus]12. Initial [epsilon][sub Nd] values for the younger Taconic basin shales range from [minus]9.7 to [minus]8.4. This increase in [epsilon][sub Nd] may reflect an increased influence of terranes outboard of the Laurentian margin. Samples from the Sevier basin include those from the Blockhouse and Tellico Formations. A sample of the lower Blockhouse Fm. has an initial [epsilon][sub Nd] of [minus]9.4, while mid-formation levels have [epsilon][sub Nd] = [minus]8.8. Initial [epsilon][sub Nd] ranges from [minus]8.0 to [minus]7.2 from Tellico Formation shales. Thus a trend towards increasing [epsilon][sub Nd] with decreasing age is also seen in the Sevier basin. This again suggests the possibility of an increasing influence from nearby terranes. The fact that the [epsilon][sub Nd] values are higher in the Sevier basin than in the Taconic basin indicates that the Sevier shales received detritus with a less evolved isotopic composition. This may reflect fundamentally different sources, such as a more juvenile terrane as an important source of Sevier basin shales.« less

Lu-Hf and Sm-Nd evolution in lunar mare basalts

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

Unruh, D.M.; Stille, P.; Patchett, P.J.

1984-02-15

Lu-Hf and Sm-Nd data for mare basalts combined with Rb-Sr and total REE data taken from the literature suggest that the mare basalts were derived by small (< or =10%) degrees of partial melting of cumulate sources, but that the magma ocean from which these sources formed was light REE and Hf-enriched. Calculated source compositions range fromm lherzolite to olivine websterite. Nonmodal melting of small amounts of ilmenite (< or =3%) in the sources seems to be required by the Lu/Hf data. A comparison of the Hf and Nd isotopic characteristics between the mare basalts and terrestrial oceanic basalts revealsmore » that the epsilonHf/epsilonNd ratios of low-Ti mare basalts are much higher than in terrestrial oceanic basalts. The results are qualitatively consistent with the hypothesis that terrestrial basalt sources are partial melt residues whereas mare basalt sources are cumulates. Alternatively, the results may imply that the terrestrial mantle has evolved in two (or more) stages of evolution, and that the net effect was depletion of the mantle during the first approx.1-3 b.y. followed by enrichment during the last 1-2 b.y.; or simply that there is a difference in Lu-Hf crystal-liquid partitioning (relative to Sm-Nd) between the lunar and terrestrial mantles.« less

Os, Nd and Sr isotope and trace element geochemistry of the Muli picrites: Insights into the mantle source of the Emeishan Large Igneous Province

NASA Astrophysics Data System (ADS)

Li, Jie; Xu, Ji-Feng; Suzuki, Katsuhiko; He, Bin; Xu, Yi-Gang; Ren, Zhong-Yuan

2010-09-01

A suite of picrites and basalts from the Muli area, in the northwestern part of the Emeishan continental flood basalt province, provides new and valuable information on the geochemistry of the Emeishan Large Igneous Province (LIP) and its source. The Muli picrites can be classified as type-1 or type-2. The former shows ocean-island basalt-like trace element characteristics, with γ Os (260 Ma) values and ɛ Nd (260 Ma) values ranging from + 7.5 to + 11.5 and from + 6.0 to + 7.8, respectively. This is the first time that picrites with highly radiogenic Os and high Os contents (up to 3.3 ppb) have been recognized in the Emeishan LIP. These characteristics probably reflect a relatively enriched component in the Emeishan LIP source. The type-2 picrites are characterized by non-radiogenic γ Os (260 Ma) values ranging from - 4.2 to - 0.3, and they may be further subdivided into type-2A and type-2B picrites. Type-2A picrites contain moderate amounts of the light rare earth elements (LREEs), have low Ce N/Yb N values (1.1-2.0), and a relatively high initial ɛ Nd (+ 5.0 to + 6.6). In terms of Os and Nd isotopes, the Muli type-2A picrites are similar to the Song Da komatiites of Vietnam and the Gorgona Island picrites, revealing the existence of a depleted mantle component in the Emeishan LIP source. In contrast with the type-2A picrites, type-2B lavas exhibit a negative Nb anomaly and relatively lower initial ɛ Nd and γ Os values (Nb/La > 1.8; ɛ Nd (260 Ma) = - 5.5 to + 6.4; γ Os (260 Ma) = - 4.2 to - 1.9), suggesting that the type-2B lavas have a depleted mantle source, similar to type-2A, but that the type-2B lavas are also influenced by various degrees of mixing of depleted plume-derived melt, sub-continental lithospheric mantle, and/or continental crust. Given that the basalts in the Muli area show similar geochemical features to those of the type-2B picrites, their origins are inferred to be similar.

Hf-Nd isotopic variability in mineral dust from Chinese and Mongolian deserts: implications for sources and dispersal

PubMed Central

Zhao, Wancang; Sun, Youbin; Balsam, William; Lu, Huayu; Liu, Lianwen; Chen, Jun; Ji, Junfeng

2014-01-01

Mineral dust provenances are closely related to the orogenic processes which may have distinct Hf-Nd isotopic signatures. Here we report the clay-sized (<2 μm) Hf-Nd isotope data from Asian dust sources to better constrain the source and transport dynamics of dust deposition in the North Pacific. Our results show that there is a more positive radiogenic Hf isotopic composition with clay-sized fractions than the corresponding bulk sample and a decoupling of the Hf-Nd couplets in the clay formation during the weathering process. The clay-sized Hf-Nd isotopic compositions of the desert samples from the Sino-Korean-Tarim Craton (SKTC) are different from those of the Gobi and deserts from the Central Asian Orogeny Belt (CAOB) due to varying tectonic and weathering controls. The Hf-Nd isotopic compositions of dust in the North Pacific central province (NPC) match closely with those from the Taklimakan, Badain Jaran and adjacent Tengger deserts, implying that the NPC dust was mainly transported from these potential sources by the westerly jet. Our study indicates that dusts from the CAOB Gobi deserts either didn't arrive in NPC or were quantitatively insignificant, but they were likely transported to the North Pacific margin province (NPM) by East Asian winter monsoon. PMID:25060781

Hf-Nd isotopic variability in mineral dust from Chinese and Mongolian deserts: implications for sources and dispersal.

PubMed

Zhao, Wancang; Sun, Youbin; Balsam, William; Lu, Huayu; Liu, Lianwen; Chen, Jun; Ji, Junfeng

2014-07-25

Mineral dust provenances are closely related to the orogenic processes which may have distinct Hf-Nd isotopic signatures. Here we report the clay-sized (<2 μm) Hf-Nd isotope data from Asian dust sources to better constrain the source and transport dynamics of dust deposition in the North Pacific. Our results show that there is a more positive radiogenic Hf isotopic composition with clay-sized fractions than the corresponding bulk sample and a decoupling of the Hf-Nd couplets in the clay formation during the weathering process. The clay-sized Hf-Nd isotopic compositions of the desert samples from the Sino-Korean-Tarim Craton (SKTC) are different from those of the Gobi and deserts from the Central Asian Orogeny Belt (CAOB) due to varying tectonic and weathering controls. The Hf-Nd isotopic compositions of dust in the North Pacific central province (NPC) match closely with those from the Taklimakan, Badain Jaran and adjacent Tengger deserts, implying that the NPC dust was mainly transported from these potential sources by the westerly jet. Our study indicates that dusts from the CAOB Gobi deserts either didn't arrive in NPC or were quantitatively insignificant, but they were likely transported to the North Pacific margin province (NPM) by East Asian winter monsoon.

Geochemical and Isotopic Evidences of the Magmatic Sources in the Eastern Sector of the Trans-Mexican Volcanic Belt: Xihuingo-Chichicuautla Volcanic Field

NASA Astrophysics Data System (ADS)

Valadez, S.; Martinez-serrano, R.; Juarez-Lopez, K.; Solis-Pichardo, G.; Perez-Arvizu, O.

2011-12-01

The study of magmatism in the Trans-Mexican Volcanic Belt (TMVB) has great importance due to several features such as its obliquity with respect to the Middle American Trench and its petrological and geochemical variability, which are not common in most typical volcanic arcs. Although several papers have contributed significantly to the understanding of most important magmatic processes in this province, there are still several questions such as the characterization of magmatic sources. In the present work, we provide new stratigraphic, petrographic, geochemical and Sr, Nd and Pb isotopic data as well as some K-Ar age determinations from the Xihuingo-Chichicuautla volcanic field (XCVF), located at the eastern part of the TMVB, with the aim to identify the magmatic sources that produced the main volcanic rocks. The volcanic structures in the XCVF are divided in two main groups according to the petrographic and geochemical compositions: 1) dacitic domes, andesitic lava flows and some dacitic-rhyolitic ignimbrites and 2) scoria cones, shield volcanoes and associated lava flows of basalt to basaltic-andesite composition. Distribution of most volcanic structures is probably controlled by NE-SW fault and fractures system. This fault system was studied by other authors who established that volcanic activity started ca. 13.5 Ma ago, followed by a volcanic hiatus of ca. 10 Ma, and the late volcanic activity began ca. 3 to 1 Ma. In this work we dated 2 rock samples by K-Ar method, which yielded ages of 402 and 871 Ka, which correspond to the most recent volcanic activity in this study area. The volcanic rocks of the XCVF display compositions from basalts to rhyolites but in general all rocks show trace element patterns typical of magmatic arcs. However, we can identify two main magmatic sources: a depleted magmatic source represented by dacitic-andesitic rocks which present a LILE enrichment with respect to HFSE indicating that a magmatic source was modified by fluids derived from the subduction processes. These magmas probably suffered fractional crystallization and minor assimilation in the continental crust. Sr, Nd isotopic compositions for this first group display the most radiogenic values (87Sr/86Sr from 0.7046 to 0.7047 and ɛNd from 2.2 to 2.8). The second source for the basaltic-andesite and basalt could be associated with an enriched mantle. These rocks present a minor LILE enrichment with respect to HSFE, and Sr and Nd isotopic values less radiogenic than the felsic rocks of the first group (87Sr/86Sr from 0.7040 to 0.7045 and ɛNd from 3.1 to 4.8). According to these evidences we can establish that the magmas emplaced in the study area were produced from a heterogeneous mantle source with complex magmatic processes combined with different interaction degrees between the magmas and continental crust.

Agile Methods: Selected DoD Management and Acquisition Concerns

DTIC Science & Technology

2011-10-01

SIDRE Software Intensive Innovative Development and Reengineering/Evolution SLIM Software Lifecycle Management -Estimate SLOC source lines of code...ISBN #0321502752 Coaching Agile Teams Lyssa Adkins ISBN #0321637704 Agile Project Management : Creating Innovative Products – Second Edition Jim...Accessed July 13, 2011. [Highsmith 2009] Highsmith, J. Agile Project Management : Creating Innovative Products, 2nd ed. Addison- Wesley, 2009

Photoionization study of the F2+ ion via the screening constant by unit nuclear charge method

NASA Astrophysics Data System (ADS)

Dieng, M.; Tine, M.; Sow, M.; Diop, B.; Guèye, M.; Faye, M.; Sakho, I.; Biaye, M.; Wagué, A.

2014-03-01

In this paper, we have tabulated energy resonances of the 2s22p2 (1D)nd (2L), 2s22p2 (1S)nd (2L) and 2s22p3 (3D)np Rydberg series originating from the 2s22p3(2Po) and from the 2s22p3 (2Do) metastable states of F2+. In addition, energy resonances of the 2s2p3(5So)np (4P) Rydberg series originating from the 2s22p3 (4So) ground-state of F2+are also reported. Calculations are performed using the Screening constant by unit nuclear charge (SCUNC) method. Analysis of the present data is achieved by calculating the quantum defects and the effective nuclear charges for each series. The present results agree very well with the Advanced Light Source experiments on F2+ (Aguilar et al., 2005). Upto n=30, the present quantum defects are almost constant and the effective charge decreases regularly toward the electric charge of the F3+ core ion along each series.

A method for combined Sr-Nd-Hf isotopic analysis of <10 mg dust samples: implication for ice core science

NASA Astrophysics Data System (ADS)

Ujvari, Gabor; Wegner, Wencke; Klötzli, Urs

2017-04-01

Aeolian mineral dust particles below the size of 10-20 μm often experience longer distance transport in the atmosphere, and thus Aeolian dust is considered an important tracer of large-scale atmospheric circulation. Since ice core dust is purely Aeolian in origin, discrimination of its potential source region(s) can contribute to a better understanding of past dust activity and climatic/environmental causes. Furthermore, ice core dust source information provides critical experimental constraints for model simulations of past atmospheric circulation patterns [1,2]. However, to identify dust sources in past dust archives such as ice cores, the mineralogy and geochemistry of the wind-blown dust material must be characterized. While the amount of dust in marine cores or common terrestrial archives is sufficient for different types of analyses and even for multiple repeat measurements, dust content in ice cores is usually extremely low even for the peak dusty periods such as the Last Glacial Maximum (LGM) (5-8 mg dust/kg ice; [3]). Since the most powerful dust fingerprinting methods, such as REE composition and Sr-Nd-Pb isotopic analyses are destructive there is a clear need to establish sequential separation techniques of Sr, Nd, Pb and other REEs to get the most information out of small (5-10 mg) dust samples recovered from ice cores. Although Hf isotopes have recently been added as a robust tool of aerosol/dust source discrimination (e.g. [4,5,6,7]), precise Hf isotopic measurements of small (<10 mg) dust samples are still challenging due to the small Hf amounts (on the order of 1-10 ng) and often compromised by potential problems arising during ion exchange chemistry. In this pilot study an improved method for chemical separation of Sr, Nd and Hf by Bast et al. [8] was applied, which allows the precise isotope analysis of sub-ng amounts of Hf by MC-ICPMS. This ion exchange chromatography procedure has been combined with established methods of separating and purifying Sr and Nd for subsequent TIMS isotopic measurements. International rock standard BCR-2 (10 mg aliquot) gave 87Sr/86Sr, 143Nd/144Nd and 176Hf/177Hf isotopic ratios of 0.705127±0.000004 (2σ), 0.512625±0.000004 and 0.282853±0.000006, respectively. These data are in good agreement with the certified values (0.705000±0.0000011, 0.512637±0.000013 and 0.282866±0.000011; [9]) demonstrating that the experimental procedures and setup allow for valid 176Lu and 176Yb corrections and results in reliable 176Hf/177Hf (and also 87Sr/86Sr, 143Nd/144Nd) ratios. Along with the standards 50, 10 and 5 mg aliquots of the fine (<10 μm) fractions of three wind-blown loess sediment samples from Central Europe (NUS), China (BEI) and the US (JUD) were processed (all acetic acid treated for carbonate removal, i.e. aluminosilicate fractions were analysed). Sr isotopic compositions varied between the aliquots within a range of ˜0.00007 for the three samples. Comparison of these values with previously obtained 87Sr/86Sr isotopic ratios from the same samples (different acid/sample amounts) reveals that these values are very sensitive to the acetic acid treatment (acid molarity and amount). By contrast, Nd isotopic ratios do not seem to be affected by acid treatment and these signatures are extremely stable both within run (0.000008 variability for the three aliquots, i.e. 0.15 ɛNd unit) and between runs of different laboratories (0.00006, ca 1 ɛNd unit). Hf isotopic compositions varied within 1 (NUS) and 5 ɛHf units (BEI) between the three aliquots, but the BEI sample always gave more positive ɛHf values (mostly below -4.7) than the Central European sample (NUS, above -6.5, mostly around -8). JUD gave two values of -4.9 and -7.9. It should be further studied using other dust samples if the slightly larger dispersion in 176Hf/177Hf for the different aliquots of BEI is a unique feature or not. Nevertheless, the ca. 3-7 ɛHf unit difference between the Central European and Chinese dust sample provides an opportunity to better discriminate last glacial Greenland dust sources [7] in Nd-Hf space. This study was supported by the OMAA 92öu7 project, the OTKA PD-108639 grant and the Bolyai János Research Fellowship (to GÚ). References [1] Biscaye et al., 1997. J. Geophys. Res. 102, 26765-26781; [2] Svensson et al., 2000. J. Geophys. Res. 105, 4637-4656; [3] Ruth et al., 2003. J. Geophys. Res. 108(D3), 4098; [4] Aciego et al., 2009. Chem. Geol. 266, 194-204; [5] Aarons et al., 2013. Chem. Geol. 349(350), 18-26; [6] Zhao et al., 2015. Geophys. Res. Lett. 42, 5661-5669; [7] Újvári et al., 2015. Geophys. Res. Lett. 42, 10399-10408; [8] Bast et al., 2015. J. Anal. Atom. Spectrom. 30, 2323; [9] Jweda et al., 2016. Geostand. Geoanal. Res. 40, 101-105.

Long Term Measurement of the Vapor Pressure of Gold in the Au-C System

NASA Technical Reports Server (NTRS)

Copland, Evan H.

2009-01-01

Incorporating the {Au(s,l) + graphite} reference in component activity measurements made with the multiple effusion-cell vapor source mass spectrometry (multicell KEMS) technique provides a fixed temperature defining ITS-90 (T(sub mp)(Au) = 1337.33K) and a systematic method to check accuracy. Over a 2 year period delta H sub(298)Au was determined by the 2nd and 3rd law methods in 25 separate experiments and were in the ranges 362.2 plus or minus 3.3 kJmol(sup -1) and 367.8 plus or minus 1.1 kJmol(sup -1), respectively. This 5 kJmol-1 discrepancy is transferred directly to the measured activities. This is unacceptable and the source of this discrepancy needs to be understood and corrected. Accepting the 2nd law value increases p(Au) by about 50 percent, brings the 2nd and 3rd law values into agreement and removes the T dependence in the 3rd law values. While compelling, there is no way to independently determine instrument sensitivities, S(sub Au), with T in a single experiment with KEMS. This lack of capability is stopping a deeper understanding of this problem. In addition, the Au-C phase diagram suggests a eutectic invariant reaction: L-Au(4.7at%C) = FCC-Au(0.08at%C) + C(graphite) at T(sub e) approximately 1323K. This high C concentration in Au(l) must reduce p(Au) in equilibrium with {Au(s,l) + graphite} and raises some critical questions about the Gibbs free energy functions of Au(s,l) and the Au fixed point (T(sub mp)(Au) = 1337.33K) which is always measured in graphite.

The Impact Induced Demagnetization Mechanism in NdFeB Permanent Magnets

NASA Astrophysics Data System (ADS)

Li, Yan-Feng; Zhu, Ming-Gang; Li, Wei; Zhou, Dong; Lu, Feng; Chen, Lang; Wu, Jun-Ying; Qi, Yan; Du, An

2013-09-01

Compression of unmagnetized Nd2Fe14B permanent magnets is executed by using shock waves with different pressures in a one-stage light gas gun system. The microstructure, crystal structure, and magnetic properties of the magnets are examined with scanning electronic microscopy, x-ray diffraction, hysteresis loop instruments, and a vibrating sample magnetometer, respectively. The NdFeB magnets display a demagnetization phenomenon after shock wave compression. The coercivity dropped from about 21.4 kOe to 3.2 kOe. The critical pressure of irreversible demagnetization of NdFeB magnets should be less than 4.92 GPa. The coercivity of the NdFeB magnets compressed by shock waves could be recovered after annealing at 900°C and 520°C for 2 h, sequentially. The chaotic orientation of Nd2Fe14B grains in the compressed magnets is the source of demagnetization.

Ubiquitous radiogenic Os in Miocene to recent basalts from diverse mantle domains beneath the Colorado Plateau, USA

NASA Astrophysics Data System (ADS)

Schlieder, T.; Reid, M. R.; Widom, E.; Blichert-Toft, J.

2015-12-01

The source of magmatism and mechanisms responsible for the observed geochemical signatures in Miocene to Recent Colorado Plateau (CP) basalts has been a renewed focus of investigation in light of Earthscope results. We report new Os and Nd isotopic data for magnesian basalts (Mg#=62-72) and interpret them in light of previously reported Hf isotope data to help constrain contributions from olivine-poor source lithologies and subduction-derived metasomatism in the genesis of recent CP volcanism. The basalts studied span a large range in Hf isotope compositions and represent melts last equilibrated at a variety of depths beneath the Colorado Plateau and its transition zones. We distinguished at least three mantle domains on the basis of paired Hf-Nd isotope, other isotopic, and geochemical characteristics of CP lavas. Domain 1 likely represents a depleted, variably metasomatized, lithospheric source, with relatively radiogenic ɛHf (+5.2 to +11.8) and highly variable ɛNd (-6.2 to +6.2). Domain 2 could represent either ancient or Farallon subduction-modified mantle and is displaced above the Hf-Nd mantle array (ɛHf=+1.0 to +7.3; ɛNd=-6.1 to -3.5). Domain 3 may be melts of pyroxenite/mica-rich veins or layers within lithospheric mantle and is characterized by unradiogenic Hf and Nd (ɛHf=-12.9 to +0.6; ɛNd=-10.0 to -2.9). The isotopic variability in CP-related lavas can largely be attributed to contributions from these mantle domains. Preliminary Os isotope data show no correlation with proxies for differentiation or crustal contamination. Osmium and Hf isotope compositions are negatively correlated between domains 1 and 2 (187Os/188Os=0.31 to 0.59), whereas the Os isotope ratios in two domain 3 basalts have both lower and higher values (187Os/188Os=0.25 and 0.68). Significantly, Os isotope signatures are highly radiogenic (vs. values of <0.12 for SW US peridotite xenoliths [1]), overlapping and extending the range for inferred melts of pyroxene- and mica-rich veins and/or layers [2]. Thus mafic magmatism associated with the CP appears to ubiquitously tap sources at least locally modified by processes such as recycling of ancient oceanic crust, introduction of terrigenous sediments, or subduction-related metasomatism. [1] Lee et al., Nature, 2001. [2] Carlson and Nowell, G-Cubed, 2001.

Effects of Molar Ratios and Sintering Times on Crystal Structures and Surface Morphology of Nd1+xFeO3 Oxide Alloy Prepared by using Solid Reaction Method

NASA Astrophysics Data System (ADS)

Sujiono, E. H.; Agus, J.; Samnur, S.; Triyana, K.

2018-05-01

The effects of molar ratios and sintering times on crystal structures and surface morphology on NdFeO3 oxide alloy have been studied. NdFeO3 oxide alloy formed by chemical preparation with solid reaction method using raw oxide Fe2O3 (99.9 %) and Nd2O3 (99.9 %) powders. In this article we reported the effects of molar ratios x = (–0.1, –0.2 and –0.3) and sintering times for 15 h and 20 h on crystal structures and surface morphology of Nd1+xFeO3 synthesized by solid-state reaction method. The results indicate that variation of molar ratio and sintering time has influenced the FWHM, crystalline size and grain size. The Nd1+xFeO3 have a major phase is NdFeO3, and other minor phases are Fe2O3, Nd2O3 and Nd(OH)3. The dominant intensity of hkl (121) with a value in FWHM, crystallite size, and grain size an indication the results will be applied as a gas sensor material as the focus of the further study.

Neodymium isotopes in authigenic phases, bottom waters and detrital sediments in the Gulf of Alaska and their implications for paleo-circulation reconstruction

NASA Astrophysics Data System (ADS)

Du, Jianghui; Haley, Brian A.; Mix, Alan C.

2016-11-01

The isotopic composition of neodymium (εNd) extracted from sedimentary Fe-Mn oxyhydroxide offers potential for reconstructing paleo-circulation, but its application depends on extraction methodology and the mechanisms that relate authigenic εNd to bottom water. Here we test methods to extract authigenic εNd from Gulf of Alaska (GOA) sediments and assess sources of leachate Nd, including potential contamination from trace dispersed volcanic ash. We show that one dominant phase is extracted via leaching of core-top sediments. Major and trace element geochemistry demonstrate that this phase is authigenic Fe-Mn oxyhydroxide. Contamination of leachate (authigenic) Nd from detrital sources is insignificant (<1%); our empirical results are consistent with established kinetic mineral dissolution rates and theory. Contamination of extracted εNd from leaching of volcanic ash is below analytical uncertainty. However, the εNd of core-top leachates in the GOA is consistently more radiogenic than bottom water. We infer that authigenic phases record pore water εNd, and the relationships of εNd among bottom waters, pore waters, authigenic phases and detrital sediments are primarily governed by the exposure time of bottom water to sea-floor sediments, rate of exchange across the sediment-water interface and the reactivity and composition of detrital sediments. We show that this conceptual model is applicable on the Pacific basin scale and provide a new framework to understand the role of authigenic phases in both modern and paleo-applications, including the use of authigenic εNd as a paleo-circulation tracer.

5 Ma of plume source evolution in the Niihau - Kauai - North Arch magmas, Hawaii

NASA Astrophysics Data System (ADS)

Beguelin, P.; Bizimis, M.; McIntosh, E. C.; Cousens, B.; Clague, D. A.

2017-12-01

The Hawaiian islands of Kauai, Niihau and Kaula form a 200 km wide platform across the plume track and record the longest activity record of Hawaiian volcanism ( > 5Ma) [1]. We present new Hf and high precision Pb (MC-ICP-MS with Tl addition) isotope data on 56 previously characterized [2] shield, post-shield and rejuvenated stage lavas from Kauai and Niihau, and on rejuvenated lavas from the North Arch volcanic field, 250 km NE of Kauai. These samples cover nearly the full eruptive history of Kauai and Niihau, and complete an across-plume transect of rejuvenated volcanism, along with published Kaula values [3]. In Nd-Hf-Sr-Pb isotope spaces [2], shield and post-shield lavas from Kauai and Niihau partially overlap the Koolau shield lavas (KSDP, Oahu [4]). Rejuvenated lavas from Kauai and Niihau show a 3 ɛNd units variability and overlap North Arch at a common depleted composition at ɛNd 9 and ɛHf 14. Kauai rejuvenated lavas in part overlap shield and post-shield lavas in Nd-Hf, but extend to lower ɛHf values for a given 87Sr/86Sr and ɛNd. In contrast Niihau rejuvenated lavas have higher ɛHf for a given ɛNd and 87Sr/86Sr compared to all Hawaiian shield lavas. The Niihau data cannot be explained by contribution of a proximal shield stage plume source (e.g. Niihau or Kauai). Instead it is consistent with mixing between a depleted mantle source and an enriched component with high Nd/Hf, Sr/Hf ratios, akin to a carbonatite with low ɛHf and ɛNd, and with their trace element systematics [5] . ICP-MS Pb isotope data for rejuvenated lavas from Kaula, Niihau, Kauai, and North Arch form three distinct arrays, confirming heterogeneity in the rejuvenated source. Our data is consistent with the presence of an enriched, Koolau-like component in the source of shield, post-shield and rejuvenated volcanism in Kauai and Niihau. The rejuvenated sources are heterogeneous across the plume, with the most isotopically depleted values seen in the distal North Arch volcanic field. [1] Garcia et al. (2016) GCA 185 278-301. [2] Cousens & Clague (2015) J. of Pet., egv045 [3] Bizimis et al. (2013) G3, 14(10), 4458-4478. [4] Salters et al. (2006) Contrib. to Min. and Pet. 151(3), 297-312. [5] Dixon et al. (2008) G3 9(9).

Improvement of a plasma uniformity of the 2nd ion source of KSTAR neutral beam injector.

PubMed

Jeong, S H; Kim, T S; Lee, K W; Chang, D H; In, S R; Bae, Y S

2014-02-01

The 2nd ion source of KSTAR (Korea Superconducting Tokamak Advanced Research) NBI (Neutral Beam Injector) had been developed and operated since last year. A calorimetric analysis revealed that the heat load of the back plate of the ion source is relatively higher than that of the 1st ion source of KSTAR NBI. The spatial plasma uniformity of the ion source is not good. Therefore, we intended to identify factors affecting the uniformity of a plasma density and improve it. We estimated the effects of a direction of filament current and a magnetic field configuration of the plasma generator on the plasma uniformity. We also verified that the operation conditions of an ion source could change a uniformity of the plasma density of an ion source.

Nd2Fe14C-based magnet with better permanent magnetic properties prepared by a simple mechanochemical method

NASA Astrophysics Data System (ADS)

Geng, Hongmin; Ji, Yuan; Zhang, Jingjing; Gao, Yuchao; Yan, Yu; Wang, Wenquan; Su, Feng; Du, Xiaobo

2017-11-01

Nd2Fe14C-based magnet is prepared by a mechanochemical method, namely high-energy ball-milling Nd2Fe11Bx (x = 0-0.15) alloy in heptane (C7H16), followed by annealing to 850 °C in vacuum. Under the action of high-energy ball-milling, Nd2Fe11Bx react with heptane to form NdH2+δ, Fe-(CB), C, etc. H2 is released and Nd2Fe17, Nd2Fe17Cx (x = 0-3), Nd2Fe14C, Nd carbides and α-Fe are formed in the subsequent annealing. C amount depends on ball-milling time t. Long time ball milling or high C content suppresses the formation of 2:17 phase and favors the formation of 2:14:1 phase in the final products. Excessive ball-milling results in the quick increase of α-Fe. The maximum of magnetically hard Nd2Fe14C is obtained at t = 4 h. For Nd2Fe11 samples, there exists considerable quantity of Nd carbides and α-Fe phase appears earlier and increases rapidly with extending the ball-milling time t. The addition of B element shortens the ball-milling time of the formation of maximum Nd2Fe14C and prominently suppresses the formation of Nd carbide and α-Fe. The optimum magnetic properties, coercivity iHc of 1193.7 kA/m, remanence Mr of 580.9 kA/m, maximum magnetic energy product (BH)max of 91.7 kJ/m3 is approaching to its theoretic value of 99.2 kJ/m3 for isotropic Nd2Fe14C magnet, are obtained in Nd2Fe11B0.06 alloy ball milled for 3.5 h.

Rb-Sr And Sm-Nd Ages, and Petrogenesis of Depleted Shergottite Northwest Africa 5990

NASA Technical Reports Server (NTRS)

Shih, C. Y.; Nyquist, L. E.; Reese, Y.; Irving, A. J.

2011-01-01

Northwest Africa (NWA) 5990 is a very fresh Martian meteorite recently found on Hamada du Draa, Morocco and was classified as an olivine-bearing diabasic igneous rock related to depleted shergottites [1]. The study of [1] also showed that NWA 5990 resembles QUE 94201 in chemical, textural and isotopic aspects, except QUE 94201 contains no olivine. The depleted shergottites are characterized by REE patterns that are highly depleted in LREE, older Sm-Nd ages of 327-575 Ma and highly LREE-depleted sources with Nd= +35+48 [2-7]. Age-dating these samples by Sm-Nd and Rb-Sr methods is very challenging because they have been strongly shocked and contain very low abundances of light rare earth elements (Sm and Nd), Rb and Sr. In addition, terrestrial contaminants which are commonly present in desert meteorites will compromise the equilibrium of isotopic systems. Since NWA 5990 is a very fresh meteorite, it probably has not been subject to significant desert weathering and thus is a good sample for isotopic studies. In this report, we present Rb-Sr and Sm-Nd isotopic results for NWA 5990, discuss the correlation of the determined ages with those of other depleted shergottites, especially QUE 94201, and discuss the petrogenesis of depleted shergottites.

Gateways and Water Mass Mixing in the Late Cretaceous North Atlantic

NASA Astrophysics Data System (ADS)

Asgharian Rostami, M.; Martin, E. E.; MacLeod, K. G.; Poulsen, C. J.; Vande Guchte, A.; Haynes, S.

2017-12-01

Regions of intermediate/deep water formation and water-mass mixing in the North Atlantic are poorly defined for the Late Cretaceous, a time of gateway evolution and cooler conditions following the Mid Cretaceous greenhouse. Improved proxy data combined with modeling efforts are required to effectively evaluate the relationship between CO2, paleogeography, and circulation during this cooler interval. We analyzed and compiled latest Cretaceous (79 - 66 Ma) ɛNd and δ13C records from seven bathyal (paleodepths 0.2 - 2 km) and eight abyssal (paleodepths > 2 km) sites in the North Atlantic. Data suggest local downwelling of Northern Component Water (NCW; ɛNd -9.5 and δ13C 1.7 ‰) is the primary source of intermediate/deep water masses in the basin. As this water flows southward and ages, δ13C values decrease and ɛNd values increase; however, additional chemical changes at several sites require mixing with contributions from several additional water masses. Lower ɛNd ( -10) and higher δ13C ( 1.9 ‰) values in the deep NW part of the basin indicate proximal contributions from a region draining old continental crust, potentially representing deep convection following opening of the Labrador Sea. In the deep NE Iberian Basin, higher ɛNd ( -7) and lower δ13C ( 0.8 ‰) during the Campanian suggest mixing with a Tethyan source (ɛNd -7 and δ13C 0.1 ‰) whose importance decreased with restriction of that gateway in the Maastrichtian. Data from bathyal sites suggest additional mixing. In the SE Cape Verde region, observed ɛNd variations from -10 in the Campanian to -13 and -12 in the early and late Maastrichtian, respectively, may record variations in output rates of Tethyan and/or NCW sources and Demerara Bottom Water (ɛNd -16), a proposed warm saline intermediate water mass formed in shallow, equatorial seas. Pacific inflow through the Caribbean gateway impacts intermediate sites at Blake Nose (ɛNd values -8), particularly the shallowest site during the late Maastrichtian, although this influence is greatly reduced relative to the Mid Cretaceous. We compare our proxy-based interpretations of North Atlantic intermediate/deep water circulation with model simulations of the Late Cretaceous performed using NCAR CESM1.2 that test the sensitivity of circulation to changes in atmospheric CO2 and paleogeographic gateways.

The Effect of Molar Ratio on Crystal Structure and Morphology of Nd1+XFeO3 (X=0.1, 0.2, and 0.3) Oxide Alloy Material Synthesized by Solid State Reaction Method

NASA Astrophysics Data System (ADS)

Zharvan, V.; Kamaruddin, Y. N. I.; Samnur, S.; Sujiono, E. H.

2017-05-01

Perovskite is an oxide alloy which has a structure of ABO3 (A = La, Nd, Sm, Gd; B = Fe, CO, Ni) and has an excellent catalytic activity and gas-sensitive properties. NdFeO3 and its derivatives are important candidates for gas sensors. In this study, the effect of molar ratio (x=0.1, 0.2 and 0.3) on crystal structure and morphology of Nd1+xFeO3 synthesized by solid state reaction method has been studied. Nd1+xFeO3 samples were prepared using Nd2O3 (99.99 %) and Fe2O3 (99.99 %) as precursors. All of the samples were characterized using XRD to identify the phase and using SEM to identify the morphology. The synthesized Nd1+xFeO3 samples showed that molar ratio strongly influences the intensity, FWHM, and crystalline size. The samples of Nd1+xFeO3 have homogenous morphology and have three major phases, i.e. NdFeO3, Nd(OH)3 and Nd2O3 with crystalline sizes of NdFeO3 of 137.0±0.1 nm, 152.2±0.1 nm and 137.0±0.1 nm for Nd1.1FeO3, Nd1.2FeO3, and Nd1.3FeO3, respectively. These results indicated that the sample of Nd1.2FeO3 was a good candidate for a gas sensor material.

Multi-wavelength emission through self-induced second-order wave-mixing processes from a Nd3+ doped crystalline powder random laser

NASA Astrophysics Data System (ADS)

Moura, André L.; Jerez, Vladimir; Maia, Lauro J. Q.; Gomes, Anderson S. L.; de Araújo, Cid B.

2015-09-01

Random lasers (RLs) based on neodymium ions (Nd3+) doped crystalline powders rely on multiple light scattering to sustain laser oscillation. Although Stokes and anti-Stokes Nd3+ RLs have been demonstrated, the optical gain obtained up to now was possibly not large enough to produce self-frequency conversion. Here we demonstrate self-frequency upconversion from Nd3+ doped YAl3(BO3)4 monocrystals excited at 806 nm, in resonance with the Nd3+ transition 4I9/2 → 4F5/2. Besides the observation of the RL emission at 1062 nm, self-converted second-harmonic at 531 nm, and self-sum-frequency generated emission at 459 nm due to the RL and the excitation laser at 806 nm, are reported. Additionally, second-harmonic of the excitation laser at 403 nm was generated. These results exemplify the first multi-wavelength source of radiation owing to nonlinear optical effect in a Nd3+ doped crystalline powder RL. Contrary to the RLs based on dyes, this multi-wavelength light source can be used in photonic devices due to the large durability of the gain medium.

One pot synthesis of exchange coupled Nd2Fe14B/alpha-Fe by pechini type sol-gel method.

PubMed

Hussain, Abid; Jadhav, Abhijit P; Baek, Yeon Kyung; Choi, Hul Jin; Lee, Jaeho; Kang, Young Soo

2013-11-01

In this work, a combination of nanoparticles of Nd2Fe14B hard magnetic phase and alpha-Fe soft magnetic phase were synthesized by one pot chemical synthesis technique using sol-gel method. A gel of Nd-Fe-B was prepared using NdCl3 x 6H2O, FeCl3 x 6H2O, H3BO3, citric acid, and ethylene glycol by pechini type sol-gel method. The gel was subsequently calcined and annealed to obtain the mixed oxide powders. The produced metal oxide particles were identified with XRD, SEM, TEM to obtain the crystal structure, shape and domain structure of them. The nanoparticles of mixed phase of Nd2Fe14B/alpha-Fe were obtained from these oxides by a process of reduction-diffusion in vacuum by employing CaH2 as reducing agent. During this process it was optimized by controlling temperature, reaction time and concentration of the reducing agent (CaH2). The phase formation of Nd2Fe14B was resulted by the direct diffusion of NdH2, Fe and B. The magnetic property of produced hard and soft phases was successfully identified with vibrating sample magnetometer (VSM). The mixed domains of the hard and soft phases were identified with selected area electron diffraction method (SAED) patterns.

Diode pumped, regenerative Nd:YAG ring amplifier for space application

NASA Technical Reports Server (NTRS)

Coyle, D. B.; Kay, Richard B.; Degnan, John J.; Krebs, Danny J.; Seery, Bernard D.

1992-01-01

The study reviews the research and development of a prototype laser used to study one possible method of short-pulse production and amplification, in particular, a pulsed Nd:YAG ring laser pumped by laser diode arrays and injected seeded by a 100-ps source. The diode array pumped, regenerative amplifier consists of only five optical elements, two mirrors, one thin film polarizer, one Nd:YAG crystal, and one pockels cell. The pockels cell performed both as a Q-switch and a cavity dumper for amplified pulse ejection through the thin film polarizer. The total optical efficiency was low principally due to the low gain provided by the 2-bar pumped laser head. After comparison with a computer model, a real seed threshold of about 10 exp -15 J was achieved because only about 0.1 percent of the injected energy mode-matched with the ring.

Sr-Nd-Hf Isotopic Analysis of <10 mg Dust Samples: Implications for Ice Core Dust Source Fingerprinting

NASA Astrophysics Data System (ADS)

Újvári, Gábor; Wegner, Wencke; Klötzli, Urs; Horschinegg, Monika; Hippler, Dorothee

2018-01-01

Combined Sr-Nd-Hf isotopic data of two reference materials (AGV-1/BCR2) and 50, 10, and 5 mg aliquots of carbonate-free fine grain (<10 μm) separates of three loess samples (Central Europe/NUS, China/BEI, USA/JUD) are presented. Good agreement between measured and reference Sr-Nd-Hf isotopic compositions (ICs) demonstrate that robust isotopic ratios can be obtained from 5 to 10 mg size rock samples using the ion exchange/mass spectrometry techniques applied. While 87Sr/86Sr ratios of dust aluminosilicate fractions are affected by even small changes in pretreatments, Nd isotopic ratios are found to be insensitive to acid leaching, grain-size or weathering effects. However, the Nd isotopic tracer is sometimes inconclusive in dust source fingerprinting (BEI and NUS both close to ɛNd(0) -10). Hafnium isotopic values (<10 μm fractions) are homogenous for NUS, while highly variable for BEI. This heterogeneity and vertical arrays of Hf isotopic data suggest zircon depletion effects toward the clay fractions (<2 μm). Monte Carlo simulations demonstrate that the Hf IC of the dust <10 μm fraction is influenced by both the abundance of zircons present and maturity of crustal rocks supplying this heavy mineral, while the <2 μm fraction is almost unaffected. Thus, ɛHf(0) variations in the clay fraction are largely controlled by the Hf IC of clays/heavy minerals having high Lu/Hf and radiogenic 176Hf/177Hf IC. Future work should be focused on Hf IC of both the <10 and <2 μm fractions of dust from potential source areas to gain more insight into the origin of last glacial dust in Greenland ice cores.

Method and system for knowledge discovery using non-linear statistical analysis and a 1st and 2nd tier computer program

DOEpatents

Hively, Lee M [Philadelphia, TN

2011-07-12

The invention relates to a method and apparatus for simultaneously processing different sources of test data into informational data and then processing different categories of informational data into knowledge-based data. The knowledge-based data can then be communicated between nodes in a system of multiple computers according to rules for a type of complex, hierarchical computer system modeled on a human brain.

Tracking Hadean processes in modern basalts with 142-Neodymium

NASA Astrophysics Data System (ADS)

Horan, M. F.; Carlson, R. W.; Walker, R. J.; Jackson, M.; Garçon, M.; Norman, M.

2018-02-01

The short-lived 146Sm→142 Nd isotope system (t1/2 = 103 Ma) provides constraints on the timing and processes of terrestrial silicate fractionation during the early Hadean. Although some Archean terranes preserve variability in 142Nd/144Nd, no anomalies have been resolved previously in young rocks. This study provides high precision 142Nd/144Nd data on a suite of ocean island basalts from Samoa and Hawaii previously shown to have variable depletions in 182W/184W that are inversely correlated with 3He/4He ratios. Improved analytical techniques and multiple replicate analyses of Nd show a variation in μ142 Nd values between -1.3 and +2.7 in the suite, relative to the JNdi standard. Given the reproducibility of the standard (±2.9 ppm, 2 SD), two Samoan samples exhibit resolved variability in their 142Nd/144Nd ratios outside of their 95% confidence intervals, suggesting minor variability in the Samoan hotspot. One sample from Samoa has a higher μ142 Nd of +2.7, outside the 95% confidence interval (±1.0 ppm) of the average of the JNdi standard. Limited, but resolved, variation in 142Nd/144Nd within the suite suggests the preservation of early Hadean silicate differentiation in the sources of at least some basalts from Samoa. Larger variations of 182W/184W and 3He/4He ratios in the same samples suggest that metal-silicate separation and mantle outgassing left a more persistent imprint on the accessible mantle compared to 142Nd/144Nd ratios which are impacted by early silicate differentiation.

Investigation on demagnetization of Nd2Fe14B permanent magnets induced by irradiation

NASA Astrophysics Data System (ADS)

Li, Zhefu; Jia, Yanyan; Liu, Renduo; Xu, Yuhai; Wang, Guanghong; Xia, Xiaobin

2017-12-01

Nd2Fe14B is an important component of insertion devices, which are used in synchrotron radiation sources, and could be demagnetized by irradiation. In the present study, the Monte Carlo code FLUKA was used to analyze the irradiation field of Nd2Fe14B, and it was confirmed that the main demagnetization particle was neutron. Nd2Fe14B permanent magnet samples were irradiated by Ar ions at different doses to simulate neutron irradiation damage. The hysteresis loops were measured using a vibrating sample magnetometer, and the microstructure evolutions were characterized by transmission electron microscopy. Moreover, the relationship between them was discussed. The results indicate that the decrease in saturated magnetization is caused by the changes in microstructure. The evolution of single crystals into an amorphous structure is the reason for the demagnetization phenomenon of Nd2Fe14B permanent magnets when considering its microscopic structure.

Chemical separation of Nd from geological samples for chronological studies using (146)Sm-(142)Nd and (147)Sm-(143)Nd systematics.

PubMed

Kagami, Saya; Yokoyama, Tetsuya

2016-09-21

Sm-Nd dating, which involves long-lived (147)Sm-(143)Nd and short-lived (146)Sm-(142)Nd systematics, has been widely used in the field of geosciences. To obtain precise and accurate ages of geological samples, the determination of highly precise Nd isotope ratios with nearly complete removal of Ce and Sm is indispensable to avoid mass spectral interference. In this study, we developed a three-step column chemistry procedure for separating Nd from geological samples that includes cation exchange chromatography for separating major elements from rare earth elements (REEs), oxidative extraction chromatography using Ln Resin coupled with HNO3 + KBrO3 for separating tetravalent Ce from the remaining REEs, and final purification of Nd using Ln Resin. This method enables high recovery of Nd (>91%) with effective separation of Nd from Ce and Sm (Ce/Nd < 1.2 × 10(-5) and Sm/Nd < 5.2 × 10(-6)). In addition, we devised a new method for determining Sm/Nd ratios with the isotope dilution inductively coupled plasma mass spectrometry method using (145)Nd- and (149)Sm-enriched spikes coupled with a group separation of REEs using TRU Resin. Applying the techniques developed in this study, we determined the Sm-Nd whole-rock isochron age of basaltic eucrites, yielding 4577 - 88(+ 55) Ma and 4558 ± 300 Ma for (146)Sm-(142)Nd and (147)Sm-(143)Nd systematics, respectively. Copyright © 2016 Elsevier B.V. All rights reserved.

Lunar Crustal History from Isotopic Studies of Lunar Anorthosites

NASA Technical Reports Server (NTRS)

Nyquist, Laurence E.; Shih, C.-Y.; Bogard, D. D.; Yamaguchi, A.

2010-01-01

Anorthosites occur ubiquitously within the lunar crust at depths of approx.3-30 km in apparent confirmation of the Lunar Magma Ocean (LMO) hypothesis. [1]. We will present recent chronological studies of anorthosites [2] that are relevant both to the LMO hypothesis and also to the lunar cataclysm hypothesis. Old (approx.4.4 Ga) Sm-Nd ages have been determined for some Apollo 16 anorthosites, and primitive initial Sr-87/Sr-86 ratios have been measured for several, but well-defined Rb-Sr ages concordant with the Sm-Nd ages have not been determined until now. Lunar anorthosite 67075, a Feldspathic Fragmental Breccia (FFB) collected near the rim of North Ray Crater, has concordant Sm-Nd and Rb-Sr ages of 4.47+/-0.07 Ga and 4.49+/-0.07 Ga, respectively. Initial Nd-143/Nd-144 determined from the Sm-Nd isochron corresponds to E(sub Nd,CHUR) = 0.3+/-0.5 compared to a Chondritic Uniform Reservoir, or E(sub Nd,HEDPB) = -0.6+/-0.5 compared to the initial Nd-143/Nd-144 of the HED Parent Body [3]. Lunar anorthosites tend to have E(sub Nd) > 0 when compared to CHUR, apparently inconsistent with derivation from a single lunar magma ocean. Although E(sub Nd) < 0 for some anorthosites, if lunar initial Nd-143/Nd-144 is taken equal to HEDR for the HED parent body [3], enough variability remains among the anorthosite data alone to suggest that lunar anorthosites do not derive from a single source, i.e., they are not all products of the LMO. An anorthositic clast from desert meteorite Dhofar 908 has an Ar-39-Ar-40 age of 4.42+/-0.04 Ga, the same as the 4.36-4.41+/-0.035 Ga Ar-39-Ar-40 age of anorthositic clast Y-86032,116 in Antarctic meteorite Yamato- 86032 [3,4]. Conclusions: (i) Lunar anorthosites come from diverse sources. Orbital geochemical studies confirm variability in lunar crustal composition [1, 5]. We suggest that the variability extends to anorthosites alone as shown by the Sm-Nd data (Fig. 2) and the existence of magnesian anorthosites (MAN, [6]) and "An93 anorthosites" [3,4]. (ii) Anorthositic clasts in lunar meteorites retain "high" Ar-Ar ages compared to Apollo anorthosites. This is perhaps a hint that "cataclysmic" impacts were on average less energetic in the mostly farside source regions of these meteorites than on the lunar nearside.

Role of melting process and melt-rock reaction in the formation of Jurassic MORB-type basalts (Alpine ophiolites)

NASA Astrophysics Data System (ADS)

Renna, Maria Rosaria; Tribuzio, Riccardo; Sanfilippo, Alessio; Thirlwall, Matthew

2018-04-01

This study reports a geochemical investigation of two thick basalt sequences, exposed in the Bracco-Levanto ophiolite (northern Apennine, Italy) and in the Balagne ophiolite (central-northern Corsica, France). These ophiolites are considered to represent an oceanward and a continent-near paleogeographic domain of the Jurassic Liguria-Piedmont basin. Trace elements and Nd isotopic compositions were examined to obtain information about: (1) mantle source and melting process and (2) melt-rock reactions during basalt ascent. Whole-rock analyses revealed that the Balagne basalts are slightly enriched in LREE, Nb, and Ta with respect to the Bracco-Levanto counterparts. These variations are paralleled by clinopyroxene chemistry. In particular, clinopyroxene from the Balagne basalts has higher CeN/SmN (0.4-0.3 vs. 0.2) and ZrN/YN (0.9-0.6 vs. 0.4-0.3) than that from the Bracco-Levanto basalts. The basalts from the two ophiolites have homogeneous initial Nd isotopic compositions (initial ɛ Nd from + 8.8 to + 8.6), within typical depleted mantle values, thereby excluding an origin from a lithospheric mantle source. These data also reject the involvement of contaminant crustal material, as associated continent-derived clastic sediments and radiolarian cherts have a highly radiogenic Nd isotopic fingerprint ( ɛ Nd at the time of basalt formation = - 5.5 and - 5.2, respectively). We propose that the Bracco-Levanto and the Balagne basalts formed by partial melts of a depleted mantle source, most likely containing a garnet-bearing enriched component. The decoupling between incompatible elements and Nd isotopic signature can be explained either by different degrees of partial melting of a similar asthenospheric source or by reaction of the ascending melts with a lower crustal crystal mush. Both hypotheses are reconcilable with the formation of these two basalt sequences in different domains of a nascent oceanic basin.

Spectroscopic investigations of neodymium doped barium bismuth fluoroborate glasses

NASA Astrophysics Data System (ADS)

Mariselvam, K.; Arun Kumar, R.; Manasa, P.

2018-06-01

A new series of neodymium doped barium bismuth fluoroborate glasses with the chemical composition of (70-x)H3BO3 + 5Bi2O3 + 10BaCO3 + 7.5CaF2 + 7.5ZnO + xNd2O3 (where x = 0.05, 0.1, 0.25, 0.5, 1, 2 (in wt.%) have been prepared by the conventional melt quenching method. The powder X-ray diffraction pattern confirms the amorphous nature of the prepared glasses. The Urbach energy reveals the minimum disorderness of the glass samples. Judd-Ofelt intensity parameters (Ωλ = 2, 4 and 6) were derived from the absorption spectrum and were used to calculate the emission properties. The near infrared emission spectra recorded with 808 nm laser diode excitation for different concentrations of Nd3+ ions and the emission for the 4F3/2 → 4I11/2 transition at 1060 nm found to be high intense. The measured decay curves for 4F3/2 fluorescent level exhibit single exponential nature with shortening of lifetime with increase in concentration. The laser parameters such as stimulated emission cross-section, branching ratios, gain band width and optical gain values are found to be high for BBFB:Nd3+ (0.5 wt%) glass. Hence, the results suggested that the present BBFB:Nd3+ (0.5 wt%) glass could be used as an efficient infrared laser source around 1.06 μm region.

An extremely low U Pb source in the Moon: UThPb, SmNd, RbSr, and 40Ar 39Ar isotopic systematics and age of lunar meteorite Asuka 881757

USGS Publications Warehouse

Misawa, K.; Tatsumoto, M.; Dalrymple, G.B.; Yanai, K.

1993-01-01

We have undertaken UThPb, SmNd, RbSr, and 40Ar 39Ar isotopic studies on Asuka 881757, a coarse-grained basaltic lunar meteorite whose chemical composition is close to low-Ti and very low-Ti (VLT) mare basalts. The PbPb internal isochron obtained for acid leached residues of separated mineral fractions yields an age of 3940 ?? 28 Ma, which is similar to the U-Pb (3850 ?? 150 Ma) and Th-Pb (3820 ?? 290 Ma) internal isochron ages. The Sm-Nd data for the mineral separates yield an internal isochron age of 3871 ?? 57 Ma and an initial 143Nd 144Nd value of 0.50797 ?? 10. The Rb-Sr data yield an internal isochron age of 3840 ?? 32 Ma (??(87Rb) = 1.42 ?? 10-11 yr-1) and a low initial 87Sr 86Sr ratio of 0.69910 ?? 2. The 40Ar 39Ar age spectra for a glass fragment and a maskelynitized plagioclase are relatively flat and give a weighted mean plateau age of 3798 ?? 12 Ma. We interpret these ages to indicate that the basalt crystallized from a melt 3.87 Ga ago (the Sm-Nd age) and an impact event disturbed the Rb-Sr system and completely reset the K-Ar system at 3.80 Ga. The slightly higher Pb-Pb age compared to the Sm-Nd age could be due to the secondary Pb (from terrestrial and/or lunar surface Pb contamination) that remained in the residues after acid leaching. Alternatively, the following interpretation is also possible; the meteorite crystallized at 3.94 Ga (the Pb-Pb age) and the Sm-Nd, Rb-Sr, and K-Ar systems were disturbed by an impact event at 3.80 Ga. The crystallization age obtained here is older than those reported for low-Ti basalts (3.2-3.5 Ga) and for VLT basalts (3.4 Ga), but similar to ages of some mare basalts, indicating that the basalt may have formed from a magma related to a basin-forming event (Imbrium?). The age span for VLT basalts from different sampling sites suggest that they were erupted over a wide area during an interval of at least ~500 million years. The impact event that thermally reset the K-Ar system of Asuka 881757 must have been post-Imbrium (perhaps Orientale) in age. The lead isotopic composition of Asuka 881757 is nonradiogenic compared with typical Apollo mare basalts and the estimated 238U 204Pb (??) value for the basalt source is 10 ?? 3. This source-?? value is the lowest so far measured for lunar rocks. A large positive ??{lunate}Nd value (7.4 ?? 0.5) and the time averaged 147Sm 144Nd ratio for the basalt source are similar to those for some Apollo 12, 15, and 17 basalts, suggesting a LREE-depleted mantle, which is consistent with the global magma ocean hypothesis. The U-Th-Pb, Sm-Nd, and Rb-Sr data on Asuka 881757 suggest that the basalt was derived from a low U Pb, low Rb Sr, and high Sm Nd source region, mainly composed of olivine and orthopyroxene with minor amounts of plagioclase (or clinopyroxene) and with sulfides enriched in volatile chalcophile elements. The basalt source may be deep in origin and different in chemistry from those previously estimated from studies of Apollo and Luna mare basalts, indicating heterogeneous sources for mare basalts. ?? 1993.

Lunar initial Nd-143/Nd-144 - Differential evolution of the lunar crust and mantle

NASA Technical Reports Server (NTRS)

Lugmair, G. W.; Marti, K.

1978-01-01

The Sm-Nd evolution of Apollo 15 green glass is discussed. The ICE age (intercept with chondritic evolution) of 3.8 + or - 0.4 eons overlaps the range of reported (Ar-39)-(Ar-40) ages and implies a distinct source region for green glass, characterized by very low and unfractionated REE abundances. Evidence is presented that LINd (lunar initial Nd) is compatible with a 'chondritic'-type Nd isotopic evolution as observed in the Juvinas meteorite. This normalization is used to study the Sm-Nd system of various lunar rock types. The results obtained from a limited number of rocks clearly indicate differential Sm-Nd evolution for the lunar crust and mantle. High-Ti basalts returned by the Apollo 11 and 17 missions were derived from distinct source regions. The Nd-143 evolution in KREEP requires a source region which is clearly distinct from any mantle reservoir.

Coercivity enhancement of Nd-Fe-B hot-deformed magnets by the eutectic grain boundary diffusion process using Nd-Ga-Cu and Nd-Fe-Ga-Cu alloys

NASA Astrophysics Data System (ADS)

Liu, Lihua; Sepehri-Amin, H.; Sasaki, T. T.; Ohkubo, T.; Yano, M.; Sakuma, N.; Kato, A.; Shoji, T.; Hono, K.

2018-05-01

Nd80Ga15Cu5 and Nd62Fe14Ga20Cu4 alloys were used as diffusion sources for the eutectic grain boundary diffusion process, applying to 4 mm-thick Nd-Fe-B hot-deformed magnets. Both samples showed nearly same coercivity of 2.2 T, while the sample processed with Nd62Fe14Ga20Cu4 showed smaller remanence deterioration from 1.50 T to 1.30 T, in contrast to that of the sample processed with Nd80Ga15Cu5 to 1.08 T. Mr/Ms of the initial sample and the samples processed with Nd62Fe14Ga20Cu4 and Nd80Ga15Cu5 were 0.946, 0.934 and 0.917, respectively, suggesting that the sample processed with Nd62Fe14Ga20Cu4 retains stronger c-axis texture after the diffusion process. Nd-rich phases with Ia3 ¯ and fcc structures were observed in the sample processed with Nd80Ga15Cu5, while the Nd-rich phases with the Ia3 ¯ and hcp structures were found in the sample processed with Nd62Fe14Ga20Cu4, all of which are the phases commonly observed in Nd-Fe-B sintered magnets.

Petrology and geochemistry of the Tasse mantle xenoliths of the Canadian Cordillera: A record of Archean to Quaternary mantle growth, metasomatism, removal, and melting

NASA Astrophysics Data System (ADS)

Polat, Ali; Frei, Robert; Longstaffe, Fred J.; Thorkelson, Derek J.; Friedman, Eyal

2018-07-01

Mantle xenoliths hosted by the Quaternary Tasse alkaline basalts in the Canadian Cordillera, southeastern British Columbia, are mostly spinel lherzolite originating from subcontinental lithospheric mantle. The xenoliths contain abundant feldspar veins, melt pockets and spongy clinopyroxene, recording extensive alkaline metasomatism and partial melting. Feldspar occurs as veins and interstitial crystal in melt pockets. Melt pockets occur mainly at triple junctions, along grain boundaries, and consist mainly of olivine, cpx, opx and spinel surrounded by interstitial feldspar. The Nd, Sr and Pb isotopic compositions of the xenoliths indicate that their sources are characterized by variable mixtures of depleted MORB mantle and EM1 and EM2 mantle components. Large variations in εNd values (-8.2 to +9.6) and Nd depleted mantle model ages (TDM = 66 to 3380 Ma) are consistent with multiple sources and melt extraction events, and long-term (>3300 Ma) isolation of some source regions from the convecting mantle. Samples with Archean and Paleoproterozoic Nd model ages are interpreted as either have been derived from relict Laurentian mantle pieces beneath the Cordillera or have been eroded from the root of the Laurentian craton to the east and transported to the base of the Cordilleran lithosphere by edge-driven convection currents. The oxygen isotope compositions of the xenoliths (average δ18O = +5.1 ± 0.5‰) are similar to those of depleted mantle. The average δ18O values of olivine (+5.0 ± 0.2‰), opx (+5.9 ± 0.6‰), cpx (+6.0 ± 0.6‰) and spinel (+4.5 ± 0.2‰) are similar to mantle values. Large fractionations for olivine-opx, olivine-cpx and opx-cpx pairs, however, reflect disequilibrium stemming from metasomatism and partial melting. Whole-rock trace element, Nd, Sr, Pb and O isotope compositions of the xenoliths and host alkaline basalts indicate different mantle sources for these two suites of rocks. The xenoliths were derived from shallow lithospheric sources, whereas the alkaline basalts originated from a deeper asthenospheric mantle source.

Detrital sources and water mass circulation in the tropical North Atlantic during the Late Cretaceous to Paleogene

NASA Astrophysics Data System (ADS)

Martin, E. E.; Pugh, E.; Kamenov, G. D.; MacLeod, K. G.

2014-12-01

Seawater Nd isotopes from fossil fish teeth in Campanian to Paleogene calcareous claystone on Demerara Rise in the tropical North Atlantic record a change from epsilon Nd values of -17 to -11 during the late Maastrichtian. This shift has been identified in three different Ocean Drilling Program (ODP) sites that span from 600 to 1500 m paleodepths (ODP sites 1259, 1260 and 1261) and has been interpreted as a transition from a warm saline intermediate water mass formed on the South American margin, referred to as Demerara Bottom Water, to a source from the North Atlantic. A study of corresponding detrital Sr, Nd and Pb isotopes was undertaken to confirm the isotopic values derived from fish teeth record water mass compositions rather than diagenesis or boundary exchange. Several leaching procedures designed to remove Fe-Mn oxide coatings and the seawater signature they carry from the detrital fractions were tested. Sr isotopic data indicate a 0.02 M hydroxylamine hydrochloride (HH) leach was ineffective at removing the Fe-Mn oxides whereas a 1.0 M HH leach produced detrital Sr isotopic values that were consistent for all three sites and plotted farther from the seawater value. Detrital isotopic results can be divided into three intervals: 1) 73 - 66 Ma, when DBW is present, 2) 66 - 61 Ma, during the transition to North Atlantic sources, and 3) <61 Ma, when North Atlantic sources appear to dominate. During interval 1, detrital Nd isotopes increase gradually, while Sr and Pb isotopic ratios are relatively constant. Leading into interval 2, detrital Nd isotopes are fairly constant while there is a stepwise increase in Sr and Pb isotopes. Leading into interval 3, there is a large increase in Nd and decrease in Sr isotopes and a slight decrease in Pb isotopes. The subtle differences in the timing of changes in fish teeth and detrital Nd isotopes suggest the seawater signal is responding to changes in water mass rather than changes in sediment composition (boundary exchange). The timing of the changes in detrital inputs indicates changes in provenance may correlate with the rearrangement of the currents transporting sediment to the region associated with the transition from a water mass sourced from the tropics to a more northern source.

Implications of Eocene-age Philippine Sea and forearc basalts for initiation and early history of the Izu-Bonin-Mariana arc

NASA Astrophysics Data System (ADS)

Yogodzinski, Gene M.; Bizimis, Michael; Hickey-Vargas, Rosemary; McCarthy, Anders; Hocking, Benjamin D.; Savov, Ivan P.; Ishizuka, Osamu; Arculus, Richard

2018-05-01

Whole-rock isotope ratio (Hf, Nd, Pb, Sr) and trace element data for basement rocks at ocean drilling Sites U1438, 1201 and 447 immediately west of the KPR (Kyushu-Palau Ridge) are compared to those of FAB (forearc basalts) previously interpreted to be the initial products of IBM subduction volcanism. West-of-KPR basement basalts (drill sites U1438, 1201, 447) and FAB occupy the same Hf-Nd and Pb-Pb isotopic space and share distinctive source characteristics with εHf mostly > 16.5 and up to εHf = 19.8, which is more radiogenic than most Indian mid-ocean ridge basalts (MORB). Lead isotopic ratios are depleted, with 206Pb/204Pb = 17.8-18.8 accompanying relatively high 208Pb/204Pb, indicating an Indian-MORB source unlike that of West Philippine Basin plume basalts. Some Sr isotopes show affects of seawater alteration, but samples with 87Sr/86Sr < 0.7034 and εNd > 8.0 appear to preserve magmatic compositions and also indicate a common source for west-of-KPR basement and FAB. Trace element ratios resistant to seawater alteration (La/Yb, Lu/Hf, Zr/Nb, Sm/Nd) in west-of-KPR basement are generally more depleted than normal MORB and so also appear similar to FAB. At Site U1438, only andesite sills intruding sedimentary rocks overlying the basement have subduction-influenced geochemical characteristics (εNd ∼ 6.6, εHf ∼ 13.8, La/Yb > 2.5, Nd/Hf ∼ 9). The key characteristic that unites drill site basement rocks west of KPR and FAB is the nature of their source, which is more depleted in lithophile trace elements than average MORB but with Hf, Nd, and Pb isotope ratios that are common in MORB. The lithophile element-depleted nature of FAB has been linked to initiation of IBM subduction in the Eocene, but Sm-Nd model ages and errorchron relationships in Site U1438 basement indicate that the depleted character of the rocks is a regional characteristic that was produced well prior to the time of subduction initiation and persists today in the source of modern IBM arc volcanic rocks with Sm/Nd > 0.34 and εNd ∼ 9.0.

Signal or noise? Separating grain size-dependent Nd isotope variability from provenance shifts in Indus delta sediments, Pakistan

NASA Astrophysics Data System (ADS)

Jonell, T. N.; Li, Y.; Blusztajn, J.; Giosan, L.; Clift, P. D.

2017-12-01

Rare earth element (REE) radioisotope systems, such as neodymium (Nd), have been traditionally used as powerful tracers of source provenance, chemical weathering intensity, and sedimentary processes over geologic timescales. More recently, the effects of physical fractionation (hydraulic sorting) of sediments during transport have called into question the utility of Nd isotopes as a provenance tool. Is source terrane Nd provenance resolvable if sediment transport strongly induces noise? Can grain-size sorting effects be quantified? This study works to address such questions by utilizing grain size analysis, trace element geochemistry, and Nd isotope geochemistry of bulk and grain-size fractions (<63μm, 63-125 μm, 125-250 μm) from the Indus delta of Pakistan. Here we evaluate how grain size effects drive Nd isotope variability and further resolve the total uncertainties associated with Nd isotope compositions of bulk sediments. Results from the Indus delta indicate bulk sediment ɛNd compositions are most similar to the <63 µm fraction as a result of strong mineralogical control on bulk compositions by silt- to clay-sized monazite and/or allanite. Replicate analyses determine that the best reproducibility (± 0.15 ɛNd points) is observed in the 125-250 µm fraction. The bulk and finest fractions display the worst reproducibility (±0.3 ɛNd points). Standard deviations (2σ) indicate that bulk sediment uncertainties are no more than ±1.0 ɛNd points. This argues that excursions of ≥1.0 ɛNd points in any bulk Indus delta sediments must in part reflect an external shift in provenance irrespective of sample composition, grain size, and grain size distribution. Sample standard deviations (2s) estimate that any terrigenous bulk sediment composition should vary no greater than ±1.1 ɛNd points if provenance remains constant. Findings from this study indicate that although there are grain-size dependent Nd isotope effects, they are minimal in the Indus delta such that resolvable provenance-driven trends can be identified in bulk sediment ɛNd compositions over the last 20 k.y., and that overall provenance trends remain consistent with previous findings.

Abnormal variation of magnetic properties with Ce content in (PrNdCe)2Fe14B sintered magnets prepared by dual alloy method

NASA Astrophysics Data System (ADS)

Xue-Feng, Zhang; Jian-Ting, Lan; Zhu-Bai, Li; Yan-Li, Liu; Le-Le, Zhang; Yong-Feng, Li; Qian, Zhao

2016-05-01

Resource-saving (PrNdCe)2Fe14B sintered magnets with nominal composition (PrNd)15-x Ce x Fe77B8 (x = 0-10) were prepared using a dual alloy method by mixing (PrNd)5Ce10Fe77B8 with (PrNd)15Fe77B8 powders. For Ce atomic percent of 1% and 2%, coercivity decreases dramatically. With further increase of Ce atomic percent, the coercivity increases, peaks at 6.38 kOe in (PrNd)11Ce4Fe77B8, and then declines gradually. The abnormal dependence of coercivity is likely related to the inhomogeneity of rare earth chemical composition in the intergranular phase, where PrNd concentration is strongly dependent on the additive amount of (PrNd)5Ce10Fe77B8 powders. In addition, for Ce atomic percent of 8%, 7%, and 6% the coercivity is higher than that of magnets prepared by the conventional method, which shows the advantage of the dual alloy method in preparing high abundant rare earth magnets. Project supported by the National Natural Science Foundation of China (Grant Nos. 51461033, 51571126, 51541105, and 11547032), the Natural Science Foundation of Inner Mongolia, China (Grant No. 2013MS0110), and the Inner Mongolia University of Science and Technology Innovation Fund, China.

Note: A pulsed laser ion source for linear induction accelerators

NASA Astrophysics Data System (ADS)

Zhang, H.; Zhang, K.; Shen, Y.; Jiang, X.; Dong, P.; Liu, Y.; Wang, Y.; Chen, D.; Pan, H.; Wang, W.; Jiang, W.; Long, J.; Xia, L.; Shi, J.; Zhang, L.; Deng, J.

2015-01-01

We have developed a high-current laser ion source for induction accelerators. A copper target was irradiated by a frequency-quadrupled Nd:YAG laser (266 nm) with relatively low intensities of 108 W/cm2. The laser-produced plasma supplied a large number of Cu+ ions (˜1012 ions/pulse) during several microseconds. Emission spectra of the plasma were observed and the calculated electron temperature was about 1 eV. An induction voltage adder extracted high-current ion beams over 0.5 A/cm2 from a plasma-prefilled gap. The normalized beam emittance measured by a pepper-pot method was smaller than 1 π mm mrad.

A New ɛNd Record Covering Termination II

NASA Astrophysics Data System (ADS)

Deaney, E. L.; Thornalley, D. J.; van de Flierdt, T.; Kreissig, K.; Barker, S.

2014-12-01

The 143Nd/144Nd ratio (ɛNd) of seawater is used as a quasi-conservative tracer to examine past changes in water mass composition of the deep ocean. Records of ɛNd across the last deglaciation (Termination 1, T1) provide valuable information about water mass mixing that has improved our understanding of the ocean dynamics relevant to the process of deglaciation. However, questions remain concerning end-member source characteristics and regional hydrographic processes. Here we present a high resolution record of ɛNd derived from fish debris from ODP site 1063 across Termination 2. The different external and internal forcing (e.g. insolation versus freshwater) applicable to T2 make this a useful comparator for studies focused on T1. Accordingly we find large (up to 4 ɛNd units) fluctuations across T2 that can be related to high latitude climate changes as recorded by ice cores and other high resolution climate archives. We also identify periods of extremely negative values that require new explanations for changing end-member compositions. Our results have important implications for understanding North Atlantic deep water formation processes during critical climate transitions.

Physical properties of nanoparticles Nd added Bi1.7Pb0.3Sr2Ca2Cu3Oy superconductors

NASA Astrophysics Data System (ADS)

Abbas, Muna; Abdulridha, Ali; Jassim, Amal; Hashim, Fouad

2018-05-01

Bi1.7Pb0.3Sr2Ca2Cu3Oy bulks were synthesized, with the addition of Nd2O3 nanoparticles, by the solid state reaction method. The concentrations of Nd were varied from 0.1 to 0.6. The superconducting properties of the samples were investigated and studied to determine the influence of Nd2O3 addition on superconducting properties and microstructural development. The structural characteristics of the synthesized superconductor samples were carried out through X-ray diffractions. DC Four point probe method was used to study the electrical resistivity behavior and to evaluate the transition temperature (TC) for all samples. It was found that: 0.2 weight percentage of Nd2O3 yield the highest TC 123 K for highest volume fraction of 2223-phase, while excessive addition decreased both of them. The results point to compelling indications of correlations between charge carriers and superconductivity. Energy-dispersive X-ray spectroscopy (EDX) analysis for Bi1.7Pb0.3Nd0.2Sr2Ca2Cu3Oy superconductor shows that Nd may be substituted at Ca sites creating point defects, which act as flux pinning centers. Scanning electron microscopy (SEM) was employed to examine the microstructure of some samples. Their results showed precipitation of Nd nanoparticles on the surface as plate-like grains.

Controlled synthesis, characterization and photoluminescence property of olive-like tetragonal α-Nd{sub 2}(MoO{sub 4}){sub 3}

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

Zhang, Youjin, E-mail: zyj@ustc.edu.cn; Zheng, Ao; Yang, Xiaozhi

2012-09-15

Highlights: ► The olive-like tetragonal α-Nd{sub 2}(MoO{sub 4}){sub 3} was gained with EDTA assisted hydrothermal method. ► The product was characterized by XRD, XPS, FTIR, FESEM, and PL. ► The possible formation mechanism for olive-like α-Nd{sub 2}(MoO{sub 4}){sub 3} was proposed. ► The PL in visible region of the olive-like α-Nd{sub 2}(MoO{sub 4}){sub 3} was studied. -- Abstract: The olive-like tetragonal α-Nd{sub 2}(MoO{sub 4}){sub 3} was obtained by a convenient and facile complex agent assisted hydrothermal method. The product was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR) spectroscopy, field-emission scanning electron microscopy (FESEM) andmore » photoluminescence (PL). The possible formation mechanism of the olive-like α-Nd{sub 2}(MoO{sub 4}){sub 3} was proposed. The photoluminescence property in visible region of the olive-like tetragonal α-Nd{sub 2}(MoO{sub 4}){sub 3} was studied.« less

The Sm-(146,147)-Nd-(142,143) formation interval for the lunar mantle and implications for lunar evolution

NASA Technical Reports Server (NTRS)

Nyquist, L. E.; Shih, C.-Y.; Wiesmann, H.; Bansal, B. M.

1993-01-01

Small anomalies in the isotopic abundance of Nd-142 have been measured for two A17 high-Ti basalts, ilmenite basalt 12056, olivine-pigeonite basalt 12039, feldspathic basalt 12038, and two KREEP basalts. These anomalies correlate with Sm-147/Nd-144 for the basalt source regions as calculated from initial Nd-143/Nd-144 ratios in the basalts, and are interpreted to be from decay of Sm-146 (t sub 1/2 = 103 Ma) in distinct lunar mantle reservoirs. A three-stage model for evolution of Nd-143/Nd-144 and Nd-142/Nd-144 yields reservoir Sm-147/Nd-144 ratios which, with the Nd-142/Nd-144 ratios in the basalts, form a 'mantle isochron' giving a lunar mantle formation interval of 94+2230 Ma (2c(rho)). Calculated reservoir Sm/Nd ratios are in the range expected from some earlier models of basalt petrogenesis. The isochron value of Nd-142/Nd-144 at Sm-147/Nd-144 sub CHUR = 0.1967 is within error limits of the average Nd-142/Nd-144 measured for an L6 chondrite, an H5 chondrite, and the Orgueil carbonaceous chondrite. Evolution of Nd-143 and Nd-142 for high-Ti basalt 70135 was modeled precisely, starting from chondritic relative REE and Nd-isotopic abundances and using the initial (Sm-146/Sm-144) sub 0 ratio inferred from a previous study of angrite LEW86010 as the initial solar system value of this parameter. We infer that the initial Sm/Nd ratio in precursor lunar materials was very nearly chondritic (within approximately 8 percent) prior to lunar differentiation.

Komatiites of the Onverwacht Group, S. Africa: REE geochemistry, Sm/Nd age and mantle evolution

NASA Astrophysics Data System (ADS)

Jahn, Bor-Ming; Gruau, G.; Glikson, A. Y.

1982-08-01

Komatiites of the Tjakastad Subgroup of the Onverwacht Group (S. Africa) were dated by the Sm/Nd method. A whole-rock isochron yields an age of 3.56±0.24 (2 σ) AE, with initial 143Nd/144Nd ratio of 0.50818±23 (2 σ), corresponding to ɛ Nd( T)= + 1.9±4.5. This age is interpreted as the time of initial Onverwacht volcanism. This result agrees with earlier Sm/Nd data of Hamilton et al. (1979) and is consistent with the Rb-Sr result of Jahn and Shih (1974). Komatiites may be divided into 3 groups based on the typology of heavy REE distributions (Jahn and Gruau 1981). According to this scheme, the Onverwacht komatiites of the present study belong to two groups: the predominant Group II rocks showing (Gd/Yb)N≃1.4, CaO/Al2O3 = 1.33, Al2O3/TiO2≃10.6; and the subordinate Group III rocks with (Gd/Yb)N<1.0; CaO/Al2O3≃0.6 and A12O3/ TiO2≃40. This contrasting feature is best explained by garnet fractionation within the mantle sources. Younger komatiites (˜2.7 AE) from Finland, Canada, Rhodesia, and Australia have (Gd/Yb)N≃1.0, CaO/ Al2O3<1.1 and Al2O3/TiO2≃21 based on 58 analyses. These ratios are nearly chondritic or of the bulk earth value (Anders 1977). It appears that some late Archean komatiites are different in chemistry from many early Archean komatiites. This may imply that the upper mantle chemistry has evolved through Archean times. However, the age connotation of the chemical parameters, such as CaO/Al2O3, (Gd/Yb)N or Al2O3/TiO2 ratio has not been firmly established. The characteristic “high” CaO/Al2O3 or (Gd/Yb)N ratios in many Onverwacht Group rocks can also be explained as a result of local short-term mantle heterogeneity.

Survey of NASA V and V Processes/Methods

NASA Technical Reports Server (NTRS)

Pecheur, Charles; Nelson, Stacy

2002-01-01

The purpose of this report is to describe current NASA Verification and Validation (V&V) techniques and to explain how these techniques are applicable to 2nd Generation RLV Integrated Vehicle Health Management (IVHM) software. It also contains recommendations for special V&V requirements for IVHM. This report is divided into the following three sections: 1) Survey - Current NASA V&V Processes/Methods; 2) Applicability of NASA V&V to 2nd Generation RLV IVHM; and 3) Special 2nd Generation RLV IVHM V&V Requirements.

Holocene provenance shift of suspended particulate matter in the Amazon River basin

NASA Astrophysics Data System (ADS)

Höppner, Natalie; Lucassen, Friedrich; Chiessi, Cristiano M.; Sawakuchi, André O.; Kasemann, Simone A.

2018-06-01

The strontium (Sr), neodymium (Nd) and lead (Pb) isotope signatures of suspended particulate matter (SPM) in rivers reflect the radiogenic isotope signatures of the rivers' drainage basin. These signatures are not significantly affected by weathering, transport or depositional cycles, but document the sedimentary contributions of the respective sources. We report new Sr, Nd and Pb isotope ratios and element concentrations of modern SPM from the Brazilian Amazon River basin and document the past evolution of the basin by analyzing radiogenic isotopes of a marine sediment core from the slope off French Guiana archiving the last 40 kyr of Amazon River SPM, and the Holocene section of sediment cores raised between the Amazon River mouth and the slope off French Guiana. The composition of modern SPM confirms two main source areas, the Andes and the cratonic Shield. In the marine sediment core notable changes occurred during the second phase of Heinrich Stadial 1 (i.e. increased proportion of Shield rivers SPM) and during the last deglaciation (i.e. increased proportion of Madeira River SPM) together with elsewhere constant source contributions. Furthermore, we report a prominent offset in Sr and Nd isotopic composition between the average core value (εNd: -11.7 ± 0.9 (2SD), 87Sr/86Sr: 0.7229 ± 0.0016 (2SD)) and the average modern Amazon River SPM signal (εNd: -10.5 ± 0.5 (2SD), 87Sr/86Sr: 0.7213 ± 0.0036 (2SD)). We suggest that a permanent change in the Amazon River basin sediment supply during the late Holocene to a more Andean dominated SPM was responsible for the offset.

The Early Differentiation History of Mars from W-182-Nd-142 Isotope Systematics in the SNC Meteorites

NASA Technical Reports Server (NTRS)

Foley, C. Nicole; Wadhwa, M.; Borg, L. E.; Janney, P. E.; Hines, R.; Grove, T. L.

2005-01-01

We report here the results of an investigation of W and Nd isotopes in the SNC (Shergottite-Nakhlite-Chassignite (martian)) meteorites. We have determined that epsilon W-182 values in the nakhlites are uniform within analytical uncertainties and have an average value of approx. 3. Also, while epsilon W-182 values in the shergottites have a limited range (from 0.3-0.7), their epsilon Nd-142 values vary considerably (from -0.2-0.9). There appears to be no correlation between epsilon W-182 and epsilon Nd-142 in the nakhlites and shergottites. These results shed new light on early differentiation processes on Mars, particularly on the timing and nature of fractionation in silicate reservoirs. Assuming a two-stage model, the metallic core is estimated to have formed at approx. 12 Myr after the beginning of the solar system. Major silicate differentiation established the nakhlite source reservoir before approx. 4542 Ma and the shergottite source reservoirs at 4525 [sup +19 sub -21] Ma. These ages imply that, within the uncertainties afforded by the Hf-182-W-182 and Sm-146-Nd-142 chronometers, the silicate differentiation events that established the source reservoirs of the nakhlites and shergottites may have occurred contemporaneously, possibly during crystallization of a global magma ocean. The distinct W-182-Nd-142 isotope systematics in the nakhlites and the shergottites imply the presence of at least three isotopically distinct silicate reservoirs on Mars, two of which are depleted in incompatible lithophile elements relative to chondrites, and the third is enriched. The two depleted silicate reservoirs most likely reside in the Martian mantle, while the enriched reservoir could be either in the crust or the mantle. Therefore, the W-182-Nd-142 isotope systematics indicate that the nakhlites and the shergottites originated from distinct source reservoirs and cannot be petrogenetically related. A further implication is that the source reservoirs of the nakhlites and shergottites on Mars have been isolated since their establishment before approx. 4.5 Ga. Therefore, there has been no giant impact or efficient global mantle convection to thoroughly homogenize the Martian mantle following the establishment of the SNC source reservoirs.

Tracing Nile sediment sources by Sr and Nd isotope signatures (Uganda, Ethiopia, Sudan)

NASA Astrophysics Data System (ADS)

Padoan, Marta; Garzanti, Eduardo; Harlavan, Yehudit; Villa, Igor Maria

2011-06-01

Strontium and neodymium isotopes, measured on diverse mud and sand fractions of sediment in transit along all major Nile branches, identify detritus sourced from Precambrian basements, Mesozoic strata, and Tertiary volcanic rocks exposed along the shoulders of the East African rift and in Ethiopian highlands. Sr and Nd isotopic ratios reflect the weighted average of detrital components generated in different catchments, allowing us to discriminate provenance, calculate sediment budgets, and investigate grain-size and hydraulic-sorting effects. 87Sr/ 86Sr and 143Nd/ 144Nd range, respectively, from as high as 0.722 and as low as 0.5108 for sediment derived from Archean gneisses in northern Uganda, to 0.705 and 0.5127 for sediment derived from Neoproterozoic Ethiopian and Eritrean basements. 87Sr/ 86Sr and 143Nd/ 144Nd, ranging 0.705-0.709 and 0.5124-0.5130 for Blue Nile tributaries, are 0.704-0.705 and 0.5127-0.5128 for largely volcaniclastic sediments of River Tekeze-Atbara, and 0.705-0.706 and 0.5126-0.5127 for main Nile sediments upstream Lake Nasser. Model mantle derivation ages ( tDM), oldest in Uganda where sediment is principally derived from the Congo Craton (3.4-3.0 Ga for Victoria and Albert Nile), progressively decrease northward across the Saharan Metacraton, from 2.6 Ga (Bahr el Jebel in South Sudan), to 2.4-2.2 Ga (Bahr ez Zeraf across the Sudd), and finally 1.6-1.3 Ga (White Nile upstream Khartoum). Instead, tDM ages of Sobat mud increase from 0.9 to 1.5 Ga across the Machar marshes. TDM ages are younger for sediments shed by Ethiopian (1.2-0.7 Ga) and Eritrean basements (1.5-1.2 Ga), and youngest for sediments shed from Ethiopian flood basalts (0.3-0.2 Ga). Integrated geochemical, mineralogical, and settling-equivalence analyses suggest influence on the Nd isotopic signal by volcanic lithic grains and titanite rather than by LREE-rich monazite or allanite. Because contributions by ultradense minerals is subordinate, intrasample variability of Sr and Nd ratios is minor. In Blue Nile, Atbara and main Nile sediments of mixed provenance, however, the Nd ratio tends to be higher and tDM ages lower in largely volcaniclastic mud than in mixed volcaniclastic/metamorphiclastic sand. The complete geochemical database presented here, coupled with high-resolution bulk-petrography and heavy-mineral data, provides a key to reconstructing erosion patterns and detrital fluxes across the whole Nile basin, and to investigate and understand how sources of sediment have changed in the historical and pre-historical past in relation to shifting climatic zones across arid northern Africa.

Stratified NH and ND emission in the prestellar core 16293E in L1689N

NASA Astrophysics Data System (ADS)

Bacmann, A.; Daniel, F.; Caselli, P.; Ceccarelli, C.; Lis, D.; Vastel, C.; Dumouchel, F.; Lique, F.; Caux, E.

2016-03-01

Context. High degrees of deuterium fractionation are commonly found in cold prestellar cores and in the envelopes around young protostars. As it brings strong constraints to chemical models, deuterium chemistry is often used to infer core history or molecule formation pathways. Whereas a large number of observations are available regarding interstellar deuterated stable molecules, relatively little is known about the deuteration of hydride radicals, as their fundamental rotational transitions are at high frequencies where the atmosphere is mostly opaque. Aims: Nitrogen hydride radicals are important species in nitrogen chemistry, as they are thought to be related to ammonia formation. Observations have shown that ammonia is strongly deuterated, with [NH2D]/[NH3] ~ 10%. Models predict similarly high [ND]/[NH] ratios, but so far only one observational determination of this ratio is available, towards the envelope of the protostar IRAS16293-2422. To test model predictions, we aim here to determine [ND]/[NH] in a dense, starless core. Methods: We observed NH and ND in 16293E with the HIFI spectrometer on board the Herschel Space Observatory as part of the CHESS guaranteed time key programme, and derived the abundances of these two species using a non local thermodynamic equilibrium radiative transfer model. Results: Both NH and ND are detected in the source, with ND in emission and NH in absorption against the continuum that arises from the cold dust emission. Our model shows, however, that the ND emission and the NH absorption originate from different layers in the cloud, as further evidenced by their different velocities. In the central region of the core, we can set a lower limit to the [ND]/[NH] ratio of ≳2%. This estimate is consistent with recent pure gas-phase models of nitrogen chemistry. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.

The Phillips pluton, Maine, USA: evidence of heterogeneous crustal sources and implications for granite ascent and emplacement mechanisms in convergent orogens

NASA Astrophysics Data System (ADS)

Pressley, Rachel A.; Brown, Michael

1999-03-01

The Phillips pluton (age of 403.8±1.3 Ma) was assembled at a crustal level below the contemporary brittle-plastic transition during regional dextral-reverse transpressive deformation. The pluton is composed dominantly of medium- to coarse-grained leucogranite sensu lato (s.l.), but within its bounds includes decametric massive outcrop of fine- to medium-grained granodiorite (s.l.). In places, the leucogranite contains centimetric enclaves apparently of the granodiorite. Granodiorite is host to more biotite than muscovite, and more calcic, oscillatory-zoned plagioclase, compared to the leucogranite. Pegmatitic granite and composite pegmatite-aplite occur as metric sheets within the pluton and as larger bodies outside the pluton to the SW. Magmatic fabrics, defined by biotite schlieren, occur locally in the leucogranite; the attitude of these fabrics and layering within the leucogranite are concordant with the NE-striking, steeply-dipping country rock foliation. K 2O contents, Rb/Sr ratios, Rb, Sr and Ba covariations, and chondrite-normalized rare earth element (REE) patterns of leucogranite are consistent with high-to-moderate a(H 2O) muscovite dehydration equilibrium eutectic melting of a predominantly pelite source similar to metasedimentary rocks of the surrounding central Maine belt (CMB). The REE patterns and Rb/Sr ratios of granodiorite also suggest derivation from a metasedimentary source, but more likely by moderate-to-low a(H 2O) (muscovite-) biotite dehydration equilibrium eutectic to non-eutectic (minimum) melting of a protolith dominated by greywacke in which garnet and plagioclase were residual phases. Both granite (s.l.) types have heterogeneous initial Nd isotope compositions. Samples of granodiorite define a range in ɛNd (404 Ma) of -1.8 to +0.1 (±0.3 2 σ uncertainty), and samples of leucogranite define a range in ɛNd (404 Ma) of -8.0 to -5.3 (±0.3 2 σ uncertainty). This bimodal distribution suggests that melts were derived from a minimum of two sources. The data are consistent with these sources being CMB metasedimentary rocks ( ɛNd (404 Ma)<-4) for the leucogranite, and Avalon-like (peri-Gondwanan) metasedimentary crust ( ɛNd (404 Ma)>-4) for the granodiorite. The range of Nd isotope compositions within each granite type most likely reflects isotopic heterogeneity inherited from the source. These data imply that the integrity of individual melt batches was maintained during ascent, and that extensive mixing of melt batches during emplacement at this level in the pluton did not occur, although centimetric enclaves have intermediate Nd isotope compositions consistent with small-scale interactions between magmas. We infer that the Phillips pluton represents the root of a larger pluton, and that what remains of this larger pluton is the feeder constructed from multiple melt batches arrested during waning flow of granite magma through a crustal-scale shear zone system.

Near-infrared luminescence of Bi2ZnOB2O6:Nd3+/PMMA composite

NASA Astrophysics Data System (ADS)

Jaroszewski, K.; Głuchowski, P.; Chrunik, M.; Jastrząb, R.; Majchrowski, A.; Kasprowicz, D.

2018-01-01

Near-infrared luminescence of a novel polymer composite system: PMMA doped with Bi2ZnOB2O6:Nd3+ microparticles, is reported for the first time. Luminescence properties of Bi2ZnOB2O6:Nd3+/PMMA were analyzed on the basis on excitation and emission spectra as well as fluorescence decay profiles. Excitation spectra monitored at 1062 nm (4F3/2 → 4I11/2) indicate numerous bands related to the optical transition of Nd3+ ions: from the 4I9/2 ground state to the 4D3/2, 2P1/2, 2K15/2, 4G7/2 + 4G9/2, 2K13/2, 4G5/2 + 2G7/2, 2H11/2, 4F9/2, 4F7/2 + 4S3/2, 4F5/2 + 2H9/2, 4F3/2 excited states. Many of them may be utilized to excite near-infrared emission of Nd3+ ions. In particular, distinctive Nd3+ emissions of the 4F3/2 → 4I9/2 and 4F3/2 → 4I11/2 transitions were detected, under excitation at 514 nm. The fluorescence decay profiles monitored at 1062 nm, excited at 514 nm, show relatively long emission lifetime of the 4F3/2 → 4I11/2 transition equal to 85 μs. Raman spectroscopy was used to determine vibrational properties and homogeneity of Bi2ZnOB2O6:Nd3+/PMMA composites. The obtained results suggest that Bi2ZnOB2O6:Nd3+/PMMA composite may be applied as an effective source of near-infrared emission in a new integrated optoelectronic devices.

Continental-scale transport of sediments by the Baltic Ice Stream elucidated by coupled grain size and Nd provenance analyses

NASA Astrophysics Data System (ADS)

Boswell, Steven M.; Toucanne, Samuel; Creyts, Timothy T.; Hemming, Sidney R.

2018-05-01

We introduce a methodology for determining the transport distance of subglacially comminuted and entrained sediments. We pilot this method on sediments from the terminal margin of the Baltic Ice Stream, the largest ice stream of the Fennoscandian Ice Sheet during the Last Glacial Maximum. A strong correlation (R2 = 0.83) between the εNd and latitudes of circum-Baltic river sediments enables us to use εNd as a calibrated measure of distance. The proportion of subglacially transported sediments in a sample is estimated from grain size ratios in the silt fraction (<63 μm). Coupled εNd and grain size analyses reveal a common erosion source for the Baltic Ice Stream sediments located near the Åland sill, more than 850 km upstream from the terminal moraines. This result is in agreement with both numerical modeling and geomorphological investigations of Fennoscandinavian erosion, and is consistent with rapid ice flow into the Baltic basins prior to the Last Glacial Maximum. The methodology introduced here could be used to infer the distances of glacigenic sediment transport from Late Pleistocene and earlier glaciations.

Is There Segregation of Rare Earth Ions in Garnet Optical Ceramics?

NASA Astrophysics Data System (ADS)

Boulon, Georges; Epicier, T.; Zhao, W.; Guzik, M.; Pan, Y.; Jiang, B.

Research on advanced optical materials for a large variety of applications is always increasing. As an example, we can note high progress in solid-state laser sources like laser-diode (LD) - pumped solid-state lasers (DPSSL) including developments of new materials and high-power laser diode led to high-power and tuneable solid-state lasers. A wide variety of materials has been studied to develop more efficient and high power microchip lasers [1]. In end-pumping schemes, in particular, materials with a short absorption length for the LD pump beam are strongly anticipated for highly efficient operations because of the excellent match between the mode and pump beam profiles. High Nd3+ concentrations were so considered such as NdP5O14, LiNdP4O12 (LNP), and NdAl3(BO3)O4. However, crystal growths of these compositions are not so easy. Cubic crystals are much more researched. When looking at the literature for actual applications, we see immediately the importance of cubic garnet crystals for which dodecahedral (Y3+), octahedral (Al3+) and tetrahedral (Al3+) sites are considered as a reservoir for many activators like: Ce3+, Nd3+, Er3+, Tm3+, Ho3+, Yb3+ rare earth ions in dodecahedral symmetry sites and transition metal ions like Cr3+ in the octahedral symmetry sites or Cr4+ in the tetrahedral symmetry sites. Among garnet crystals, Y3Al5O12 (YAG) host is the most used, commercially produced by the Czochralski method. However, in the case of the most used Nd3+: YAG laser crystal, the Nd3+ concentration that affects the performance in laser applications, is strongly limited to 0.2-1.4 Nd3+ at. % as a result of the segregation distribution coefficient [1].

East Asian origin of central Greenland last glacial dust: just one possible scenario?

NASA Astrophysics Data System (ADS)

Újvári, Gábor; Stevens, Thomas; Svensson, Anders; Klötzli, Urs Stephan; Manning, Christina; Németh, Tibor; Kovács, János

2016-04-01

Dust in Greenland ice cores is used to reconstruct the activity of dust emitting regions and atmospheric circulation for the last glacial period. However, the source dust material to Greenland over this period is the subject of considerable uncertainty. Here we use new clay mineral and Sr-Nd isotopic data from eleven loess samples collected around the Northern Hemisphere and compare the 87Sr/86Sr and 143Nd/144Nd isotopic signatures of fine (<10 μm) separates to existing Greenland ice core dust data (GISP2, GRIP; [1]; [2]). Smectite contents and kaolinite/chlorite (K/C) ratios allow exclusion of continental US dust emitting regions as potential sources, because of the very high (>3.6) K/C ratios and extremely high (>~70%) smectite contents. At the same time, Sr-Nd isotopic compositions demonstrate that ice core dust isotopic compositions can be explained by East Asian (Chinese loess) and/or Central/East Central European dust contributions. Central/East Central European loess Sr-Nd isotopic compositions overlap most with ice core dust, while the Sr isotopic signature of Chinese loess is slightly more radiogenic. Nevertheless, an admixture of 90‒10 % from Chinese loess and circum-Pacific volcanic material would also account for the Sr‒Nd isotopic ratios of central Greenland LGM dust. At the same time, sourcing of ice core dust from Alaska, continental US and NE Siberia seems less likely based on Sr and Nd isotopic signatures. The data demonstrate that currently no unique source discrimination for Greenland dust is possible using both published and our new data [3]. Thus, there is a need to identify more diagnostic tracers. Based on initial Hf isotope analyses of fine separates of three loess samples (continental US, Central Europe, China), an apparent dependence of Hf isotopic signatures on the relative proportions of radiogenic clay minerals (primarily illite) was found, as these fine dust fractions are apparently zircon-free. The observed difference between major potential source regions in 176Hf/177Hf that reach several ɛHf units and the first order clay mineralogy dependence of Hf isotopic signatures means there is strong potential for distinguishing between the two hypothesized Greenland dust sources using Hf isotopes [3]. [1] Biscaye P.E., Grousset F.E., Revel M., Van der Gaast S., Zielinski G.A., Vaars A., Kukla G. (1997). Asian provenance of glacial dust (stage 2) in the Greenland Ice Sheet Project 2 Ice Core, Summit, Greenland. Journal of Geophysical Research 102, 26765-26781. [2] Svensson A., Biscaye P.E., Grousset F.E. (2000) Characterization of late glacial continental dust in the Greenland Ice Core Project ice core. Journal of Geophysical Research 105, 4637-4656. [3] Újvári G., Stevens T., Svensson A., Klötzli U.S., Manning, C., Németh T., Kovács J., Sweeney M.R., Gocke M., Wiesenberg G.L.B., Markovic S.B., Zech M. (in press). Two possible source regions for Central Greenland last glacial dust. Geophysical Research Letters, doi: 10.1002/2015GL066153.

Extraction of seawater-derived neodymium from different phases of deep sea sediments by selective leaching

NASA Astrophysics Data System (ADS)

Blaser, P.; Lippold, J. A.; Frank, N.; Gutjahr, M.; Böhm, E.

2014-12-01

In order to deduce reliable information about the interaction of the oceans with the climate system as a whole in the past, the reconstruction of water mass circulation is crucial. The analysis of seawater-derived neodymium isotopes (143Nd/144Nd, expressed as ɛNd) in marine sediments provides a unique proxy for deep water provenance in particular in the Atlantic [1]. The ɛNd signature and thus the mixing proportion of the local bottom water masses is archived in authigenic phases in the sediment. Obtaining seawater ɛNd from authigenic accretions bound to foraminiferal tests has lately become the preferred since most reliable method [2]. Attempts have also been made to extract the Nd-rich authigenic metal fraction by leaching it off the bulk sediment and thereby use this proxy with less effort, in the highest possible resolution and in sediments where foraminifera are not sufficiently present. However, often other sedimentary components are also leached in the process and contaminate the extracted Nd [3,4]. In this project several core-top and older sediments across the Atlantic have been leached in ten consecutive steps with either dilute buffered acetic acid or an acid-reductive solution. The leachates were analysed on their elemental and Nd isotope compositions, as well as rare earth element (REE) distributions. By graduating the total leaching procedure into smaller stages the results display which processes take place in the course of sediment leaching in the laboratory and which components of the sediment are most reactive. Thus, they help to better evaluate the quality of sediment leaches for ɛNd analysis. Clearly, organic calcite acts as a fast reacting buffer and at the point where its amount is sufficiently reduced the leaching of other components commences and the Nd concentration peaks. Corruption of the extracted ɛNd signal by non-authigenic sources in many cases occured early in the leaching sequence, indicating that only very cautious leaching can reliably extract an authigenic ɛNd signal from diverse sedimentary environments. References: [1] Crocket, K. C. et al. (2011), Geology 39, 515-518 [2] Tachikawa, K. et al. (2014), Quat. Sci. Rev. 88, 1-13 [3] Elmore, A. C. et al. (2011), G³ Vol. 12/9 [4] Wilson, D. J. et al. (2013), GCA 109, 197-221

A source-depleted Early Jurassic granitic pluton from South China: Implication to the Mesozoic juvenile accretion of the South China crust

NASA Astrophysics Data System (ADS)

Zhou, Zuo-Min; Ma, Chang-Qian; Wang, Lian-Xun; Chen, Shu-Guang; Xie, Cai-Fu; Li, Yong; Liu, Wei

2018-02-01

Source-depleted granites were rarely reported in South China. Hereby we identified such a granitic pluton, the Tiandong pluton, at Northeastern Guangdong province in Southeastern (SE) China. Whole-rock Sr-Nd and zircon Hf isotopes of the Tiandong granites both revealed obviously depleted source signatures, with initial isotopic values of initial 87Sr/86Sr = 0.7032-0.7040, εNd(t) = 1.1-1.5, and εHf(t) = 6-13, respectively. Zircon U-Pb dating implied the granite was intruded in Early Jurassic (188 Ma). The dominant minerals of the Tiandong granite consist of K-feldspar, plagioclase, quartz and biotite, with accessory mineral assemblage of apatite + zircon + magnetite. Based on the mineralogy and the depleted isotopic signature, the granites chemically show I-type affinity such as low Zr + Nb + Ce + Y (131.6 to 212.2), 104 × Ga/Al (2.12-2.27), A/CNK values < 1.1 (0.97-1.03), corundum molecule < 1 (0-0.55) and extremely low P2O5 contents (0.05 wt%). The one-stage and two-stage depleted mantle Nd model ages (TDM = 0.89 to 0.84 Ga, T2DM = 0.88 to 0.85 Ga) are consistent. TDM(Hf) values of 0.31-0.63 Ga are also indistinguishable from T2DM(Hf) values of 0.35-0.75 Ga. The Nd and Hf isotopic compositions confirm that the Tiandong granites are juvenile crustal accretion but decoupled Nd-Hf isotopic systems. The juvenile crust is likely to originate from a mixed source of the primary asthenospheric mantle and the subordinate EMII. Combined with early studies of adjacent rocks, we propose that the early Jurassic ( 200-175 Ma) magmatism as evidenced by the Tiandong granites might be driven by upwelling of asthenosphere and subsequent underplating of mafic melts in an intra-plate extensional setting as a response to far-field stress during early stage subduction of the paleo-pacific plate.

Geochemical characteristics of Cretaceous carbonatites from Angola

NASA Astrophysics Data System (ADS)

Alberti, A.; Castorina, F.; Censi, P.; Comin-Chiaramonti, P.; Gomes, C. B.

1999-12-01

The Early Cretaceous (138-130 Ma) carbonatites and associated alkaline rocks of Angola belong to the Paraná-Angola-Etendeka Province and occur as ring complexes and other central-type intrusions along northeast trending tectonic lineaments, parallel to the trend of coeval Namibian alkaline complexes. Most of the Angolan carbonatite-alkaline bodies are located along the apical part of the Moçamedes Arch, a structure representing the African counterpart of the Ponta Grossa Arch in southern Brazil, where several alkaline-carbonatite complexes were also emplaced in the Early Cretaceous. Geochemical and isotopic (C, 0, Sr and Nd) characteristics determined for five carbonatitic occurrences indicate that: (1) the overall geochemical composition, including the OC isotopes, is within the range of the Early and Late Cretaceous Brazilian occurrences from the Paraná Basin; (2) the La versus {La}/{Yb} relationships are consistent with the exsolution of CO i2-rich melts from trachyphonolitic magmas; and (3) the {143Nd}/{144Nd} and {87Sr}/{86Sr} initial ratios are similar to the initial isotopic ratios (129 Ma) of alkaline complexes in northwest Namibia. In contrast, the Lupongola carbonatites have a distinctly different {143Nd}/{144Nd} initial ratio, suggesting a different source. The Angolan carbonatites have SrNd isotopic compositions ranging from bulk earth to time-integrated depleted sources. Since those from eastern Paraguay (at the western fringe of the Paraná-Angola-Etendeka Province) and Brazil appear to be related to mantle-derived melts with time-integrated enriched or B.E. isotopic characteristics, it is concluded that the carbonatites of the Paraná-Angola-Etendeka Province have compositionally distinct mantle sources. Such mantle heterogeneity is attributed to 'metasomatic processes', which would have occurred at ca 0.6-0.7 Ga (Angola, northwest Namibia and Brazil) and ca 1.8 Ga (eastern Paraguay), as suggested by Nd-model ages.

Pb, Sr, and Nd isotopic compositions of a suite of Large Archean, igneous rocks, eastern Beartooth Mountains - Implications for crust-mantle evolution

NASA Technical Reports Server (NTRS)

Wooden, J. L.; Mueller, P. A.

1988-01-01

Compositionally diverse Late Archean rocks (2.74-2.79 Ga old) from the eastern Beartooth Mountains (Montana and Wyoming) were studied and shown to have the same initial Pb, Sr, and Nd isotopic ratios. Lead and Sr initial ratios are higher and Nd initial values lower than predicted for rocks derived from model mantle sources and strongly indicate the involvement of an older crustal reservoir in the genesis of these rocks. A model involving subduction of continental detritus and contamination of the overlying mantle is suggested.

Cainozoic Orogenic Magmatism In The Western-central Mediterranean Area: Implications For The Subduction-modified Mantle Sources

NASA Astrophysics Data System (ADS)

Beccaluva, L.; Bianchini, G.; Coltorti, M.; Siena, F.; Verde, M.

In this contribution new REE and Sr-Nd isotopic data carried out on Cainozoic subduction-related volcanic rocks from the western-central Mediterranean are dis- cussed within a general review of the Cainozoic orogenic magmatism of the area. These volcanic events are related to subduction processes which occurred along the Paleo-European margin at least since Eocene and migrated (trough passive sinking and slab roll-back) southeastward up to the present in the peri-Tyrrhenian margin of Italy. Orogenic rocks from Provence (34-20 Ma) are characterised by 87Sr/86Sr be- tween 0.70453 and 0.70579, and 143Nd/144Nd between 0.51292 and 0.51265, which are consistent with mantle sources modified by subduction fluids released by altered oceanic crust. Sr-Nd isotopic composition of orogenic rocks from Sardinia (32-13 Ma), show a more complex picture: some compositions with relatively low 87Sr/86Sr (<0.706) and high 143Nd/144Nd (>0.5125), are compatible with the subduction of pure oceanic crust, while compositions with very high 87Sr/86Sr (up to 0.7113) and low 143Nd/144Nd (down to 0.51219) require additional components of continental crust affinity in the mantle wedge (partial fusion of subducted terrigenous sediments?). As concerns the Aeolian volcanics (< 1.3 Ma), compositions are compatible with man- tle sources solely enriched by fluid components from subducted oceanic crust. How- ever, it is interesting to note that shoshonites from the younger series of Stromboli display distinctly higher 87Sr/86Sr (up to 0.7075) and lower 143Nd/144Nd composi- tion (down to 0.51242), thus requiring once again recycle of continental crust materials in their mantle sources. The influence of such continental crust-derived components appear to be even more important in the mantle sources of the Campania volcanics, where extreme Sr-Nd isotopic compositions are recorded (87Sr/86Sr up to 0.7097; 143Nd/144Nd down to 0.5122).

Sources of granite magmatism in the Embu Terrane (Ribeira Belt, Brazil): Neoproterozoic crust recycling constrained by elemental and isotope (Sr-Nd-Pb) geochemistry

NASA Astrophysics Data System (ADS)

Alves, Adriana; Janasi, Valdecir de Assis; Campos Neto, Mario da Costa

2016-07-01

Whole rock elemental and Sr-Nd isotope geochemistry and in situ K-feldspar Pb isotope geochemistry were used to identify the sources involved in the genesis of Neoproterozoic granites from the Embu Terrane, Ribeira Belt, SE Brazil. Granite magmatism spanned over 200 Ma (810-580 Ma), and is dominated by crust-derived relatively low-T (850-750 °C, zircon saturation) biotite granites to biotite-muscovite granites. Two Cryogenian plutons show the least negative εNdt (-8 to -10) and highest mg# (30-40) of the whole set. Their compositions are strongly contrasted, implying distinct sources for the peraluminous (ASI ∼ 1.2) ∼660 Ma Serra do Quebra-Cangalha batholith (metasedimentary rocks from relatively young upper crust with high Rb/Sr and low Th/U) and the metaluminous (ASI = 0.96-1.00) ∼ 630 Ma Santa Catarina Granite. Although not typical, the geochemical signature of these granites may reflect a continental margin arc environment, and they could be products of a prolonged period of oceanic plate consumption started at ∼810 Ma. The predominant Ediacaran (595-580 Ma) plutons have a spread of compositions from biotite granites with SiO2 as low as ∼65% (e.g., Itapeti, Mauá, Sabaúna and Lagoinha granites) to fractionated muscovite granites (Mogi das Cruzes, Santa Branca and Guacuri granites; up to ∼75% SiO2). εNdT are characteristically negative (-12 to -18), with corresponding Nd TDM indicating sources with Paleoproterozoic mean crustal ages (2.0-2.5 Ga). The Guacuri and Santa Branca muscovite granites have the more negative εNdt, highest 87Sr/86Srt (0.714-0.717) and lowest 208Pb/206Pb and 207Pb/206Pb, consistent with an old metasedimentary source with low time-integrated Rb/Sr. However, a positive Nd-Sr isotope correlation is suggested by data from the other granites, and would be consistent with mixing between an older source predominant in the Mauá granite and a younger, high Rb/Sr source that is more abundant in the Lagoinha granite sample. The Ediacaran granites are coeval with profuse granite magmatism attributed to continental arc magmatism in northern Ribeira and Araçuaí belts. However, their evolved compositions with low mg# and dominantly peraluminous character are unlike those of magmatic arc granites, and they are more likely products of post-collisional magmatism or correspond to an inner belt of crust-derived granites.

Pb isotope compositions of modern deep sea turbidites

NASA Astrophysics Data System (ADS)

Hemming, S. R.; McLennan, S. M.

2001-01-01

Modern deep sea turbidite muds and sands collected from Lamont piston cores represent a large range in age of detrital sources as well as a spectrum of tectonic settings. Pb isotope compositions of all but three of the 66 samples lie to the right of the 4.56 Ga Geochron, and most also lie along a slope consistent with a time-integrated κ ( 232Th/ 238U) between 3.8 and 4.2. Modern deep sea turbidites show a predictable negative correlation between both Pb and Sr isotope ratios and ɛNd and ɛHf, clearly related to the age of continental sources. However, the consistency between Pb and Nd isotopes breaks down for samples with very old provenance ( ɛNd<-20) that are far less radiogenic than predicted by the negative correlation. The correlations among Sr, Nd and Hf isotopes also become more scattered in samples with very old provenance. The unradiogenic Pb isotopic character of modern sediments with Archean Nd model ages is consistent with a model where Th and U abundances of the Archean upper crust are significantly lower than the post-Archean upper crust.

Tunable cw Single-Frequency Source for Injection Seeding 2-micrometer Lasers

DTIC Science & Technology

1990-06-01

Nd:glass Slab Asilomar, CA, January, 1989. Laser for X-ray Lithography ," presented at Lasers 11. R. L. Byer, "Solid State Lasers for Accelerator 89, New...Alumni Association (Stanford Club of M.K. Reed and R.L. Byer, "A Nd:glass Slab Connecticut), April, 1989. Laserfor X-ray Lithography ," to be...and R.L. Byer, "A Nd:Glass Slab asymmetric quantum wells," invited paper QWA1 Laser for Soft X-ray Lithography ", paper MB4, International Quantum

Effects of different sources of fructans on body weight, blood metabolites and fecal bacteria in normal and obese non-diabetic and diabetic rats.

PubMed

Rendón-Huerta, Juan A; Juárez-Flores, Bertha; Pinos-Rodríguez, Juan M; Aguirre-Rivera, J Rogelio; Delgado-Portales, Rosa E

2012-03-01

Fructans contribute significantly to dietary fiber with beneficial effects on gastrointestinal physiology in healthy individuals and offer a promising approach to treating some diseases. Two experiments (Experiment 1 = rats with normal weight; Experiment 2 = obese rats) were developed to compare the effects of three fructan sources (Cichorium intybus L. Asteraceae, Helianthus tuberosus L. Asteraceae and Agave angustifolia ssp. tequilana Haw, Agavaceae) on body weight change, blood metabolites and fecal bacteria in non-diabetic (ND) and diabetic (D) rats. In Experiment 1 total body weight gain and daily feed intake in D and ND rats decreased (P < 0.05) with supplements of fructan. Only in D rats, blood glucose concentrations, fecal Clostrodium spp. counts, and liver steatosis decreased, while blood HDL concentrations and fecal Lactobacillus spp. and Bifidobacterium spp. counts increased due to fructans. In Experiment 2, total body weight gain and feed intake in ND and D rats were also decreased by fructans. In ND rats, fructan decreased blood glucose concentrations. In D rats, fructans from A. angustifolia ssp. tequilana decreased blood cholesterol and LDL and liver steatosis. For both ND and D rats, fecal Lactobacillus spp. and Bifidobacterium spp. counts were higher (P < 0.05) with fructan supplements.

Influences of neodymium doping on magnetic and electrochemical properties of Li3V2(PO4)3/C synthesized via a sol-gel method

NASA Astrophysics Data System (ADS)

Liu, Liying; Qiu, Yongbin; Mai, Yongzhi; Wu, Qibai; Zhang, Haiyan

2015-11-01

A series of neodymium doped Li3V2-xNdx(PO4)3/C cathode materials have been successfully synthesized by a citric acid assisted sol-gel method. Nd doped samples (x ≤ 0.10) have well developed monoclinic structure of Li3V2(PO4)3 with enlarged unit cell volume. All samples present typical characteristics of paramagnetism in 4 < T ≤ 300 K, but the magnetic susceptibilities of Nd doped samples increase with Nd content (except for x = 0.15). Nd doped composites show better electrochemical property than that of the undoped one. Among them, the Li3V1.95Nd0.05(PO4)3/C displays the highest capacity and best cycle stability. The Li3V1.95Nd0.05(PO4)3/C presents the first discharge capacity of 129.2 mAh g-1 at 1 C rate in the voltage range of 3.0-4.3 V, 21.7% higher than that of Li3V2(PO4)3/C. And no capacity loss occurs after 100 cycles. The high structural stability, low charge-transfer resistance and rapid Li+ diffusion due to the presence of Nd3+ are mainly responsible for the superior electrochemical performance of Nd doped Li3V2(PO4)3/C cathode materials.

Rb-Sr and Sm-Nd chronology and genealogy of mare basalts from the Sea of Tranquility

NASA Technical Reports Server (NTRS)

Papanastassiou, D. A.; Depaolo, D. J.; Wasserburg, G. J.

1977-01-01

Rb-Sr and Sm-Nd ages of two Apollo 11 mare basalts, high-K basalt 10072 and low-K basalt 10062, are reported. Rb-Sr, Sm-Nd, and Ar-40-Ar-39 ages are in good agreement and indicate an extensive time interval for filling of the Sea of Tranquility, presumably by thin lava flows, in agreement with similar observations for the Ocean of Storms. Initial Sr and Nd isotopic compositions on Apollo 11 basalts reveal at least two parent sources producing basalts. The Sm-Nd isotopic data demonstrate that low-K and high-Ti basalts from Apollo 11 and 17 derived from distinct reservoirs, while low-Ti Apollo 15 mare basalt sources have Sm/Nd similar to the sources of Apollo 11 basalts. Groupings of mare basalt based on Ti content and on isotopic data do not coincide.

Note: A pulsed laser ion source for linear induction accelerators

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

Zhang, H., E-mail: bamboobbu@hotmail.com; School of Physics, Peking University, Beijing 100871; Zhang, K.

2015-01-15

We have developed a high-current laser ion source for induction accelerators. A copper target was irradiated by a frequency-quadrupled Nd:YAG laser (266 nm) with relatively low intensities of 10{sup 8} W/cm{sup 2}. The laser-produced plasma supplied a large number of Cu{sup +} ions (∼10{sup 12} ions/pulse) during several microseconds. Emission spectra of the plasma were observed and the calculated electron temperature was about 1 eV. An induction voltage adder extracted high-current ion beams over 0.5 A/cm{sup 2} from a plasma-prefilled gap. The normalized beam emittance measured by a pepper-pot method was smaller than 1 π mm mrad.

Mantle contribution and tectonic transition in the Aqishan-Yamansu Belt, Eastern Tianshan, NW China: Insights from geochronology and geochemistry of Early Carboniferous to Early Permian felsic intrusions

NASA Astrophysics Data System (ADS)

Du, Long; Long, Xiaoping; Yuan, Chao; Zhang, Yunying; Huang, Zongying; Wang, Xinyu; Yang, Yueheng

2018-04-01

Late Paleozoic is a key period for the accretion and collision of the southern Central Asian Orogenic Belt (CAOB). Here, we present new zircon U-Pb ages, whole-rock geochemistry and Sr-Nd isotopic compositions for four Late Paleozoic felsic plutons in Eastern Tianshan (or Tienshan in some literatures) in order to constrain the tectonic evolution of the southern CAOB. The granodioritic pluton and its dioritic enclaves were synchronously formed in the Early Carboniferous (336 ± 3 Ma and 335 ± 2 Ma, respectively). These rocks are depleted in Nb, Ta and Ti, and enriched in Rb, Ba, Th and U related to the primitive mantle, which show typical features of arc rocks. They both have similar Sr-Nd isotopic ratios to those granitic rocks from the eastern Central Tianshan Block and have the latest Mesoproterozoic two stage Nd model ages (TDM2) (1111-1195 Ma for the granodioritic pluton and 1104-1108 Ma for the enclaves, respectively), indicating that their source magmas may have been derived from the Mesoproterozoic crust. The albitophyric pluton was also emplaced in the Early Carboniferous (333 ± 3 Ma). Rocks of this pluton have similar εNd(t) values (-0.69 to -0.37) and TDM2 ages (1135-1161 Ma) to those of the granodioritic rocks, suggest similar crustal source for both types of rocks. In contrast, the K-feldspar granitic and monzonitic plutons were emplaced in the Early Permian (292 ± 3 Ma and 281 ± 2 Ma, respectively). Samples of the K-feldspar granitic pluton have high K2O + Na2O, FeO/MgO, Ga/Al, HFSE (e.g., Zr and Hf) and low CaO, Sr and Ba, exhibiting characteristics of A2-type granites, which probably emplaced in a post-collisional extension environment. They have higher εNd(t) values (+2.77 to +3.27) and more juvenile TDM2 ages (799-841 Ma) than the Early Carboniferous plutons, suggesting that they were derived from relatively younger crustal sources. The monzonitic granites are metaluminous to weakly peraluminous with A/CNK ranging from 0.93 to 1.05, and have very low P2O5, indicating characteristics of I-type granites. They also have positive εNd(t) values (+2.22 to +2.34) and juvenile TDM2 ages (868-878 Ma), suggesting this pluton was also produced by partial melting of relatively young crustal source. Based on an isotopic mixing simulation, significant mantle contributions were added to the magma source of both the Early Carboniferous and the Early Permian felsic rocks. The mantle contribution changes from 60% in the Early Carboniferous to 75% in the Early Permian. The remarkably increasing of mantle materials in the magma source of the felsic rocks in the Aqishan-Yamansu belt was most likely induced by the tectonic transition from an Early Carboniferous continental arc to an Early Permian post-collisional extension environment.

Teachers' Perceptions of Students with Speech Sound Disorders: A Quantitative and Qualitative Analysis

ERIC Educational Resources Information Center

Overby, Megan; Carrell, Thomas; Bernthal, John

2007-01-01

Purpose: This study examined 2nd-grade teachers' perceptions of the academic, social, and behavioral competence of students with speech sound disorders (SSDs). Method: Forty-eight 2nd-grade teachers listened to 2 groups of sentences differing by intelligibility and pitch but spoken by a single 2nd grader. For each sentence group, teachers rated…

Scheduling of flow shop problems on 3 machines in fuzzy environment with double transport facility

NASA Astrophysics Data System (ADS)

Sathish, Shakeela; Ganesan, K.

2016-06-01

Flow shop scheduling is a decision making problem in production and manufacturing field which has a significant impact on the performance of an organization. When the machines on which jobs are to be processed are placed at different places, the transportation time plays a significant role in production. Further two different transport agents where 1st takes the job from 1st machine to 2nd machine and then returns back to the first machine and the 2nd takes the job from 2nd machine to 3rd machine and then returns back to the 2nd machine are also considered. We propose a method to minimize the total make span; without converting the fuzzy processing time to classical numbers by using a new type of fuzzy arithmetic and a fuzzy ranking method. A numerical example is provided to explain the proposed method.

Highly Efficient Nd:yag Lasers for Free-space Optical Communications

NASA Technical Reports Server (NTRS)

Sipes, D. L., Jr.

1985-01-01

A highly efficient Nd:YAG laser end-pumped by semiconductor lasers as a possible free-space optical communications source is discussed. Because this concept affords high pumping densities, a long absorption length, and excellent mode-matching characteristics, it is estimated that electrical-to-optical efficiencies greater than 5% could be achieved. Several engineering aspects such as resonator size and configuration, pump collecting optics, and thermal effects are also discussed. Finally, possible methods for combining laser-diode pumps to achieve higher output powers are illustrated.

Using Nd and Sr isotopes to trace dust and volcanic inputs to soils on French Guadeloupe Island

NASA Astrophysics Data System (ADS)

Guo, J.; Pereyra, Y.; Ma, L.; Gaillardet, J.; Sak, P. B.; Bouchez, J.

2017-12-01

Soil is at the central part of the Critical Zone for its important roles in sustaining ecosystems and agriculture. At French Guadeloupe, a tropical humid volcanic island, previous studies have shown that the mineral nutrient elements such as K, Na, Ca, and Mg are highly depleted in the surface soil. And mineral nutrients introduced by dusts are an important mineral nutrient source for vegetation growth in this area. It is important to understand and quantify the sources of the mineral dust added to surface soils. Nd isotope ratios, due to their distinct signatures between two unique end-members in soils for this area: the young volcanic areas like Guadeloupe and the dust source region from the old continental shields like Sahara Desert, can be a robust tracer to understand this critical process. Nevertheless, Sr isotope ratios can trace the inputs of marine aerosols. Here we present a new Nd isotope study on Guadeloupe soil depth profiles, combined with previous Sr isotope data, to fingerprint the sources of dust and volcanic inputs into soils. Soil samples from three surface profiles (0 - 1000cm deep) at different locations of the Guadeloupe Island were systematically analyzed. The results show distinct depth variations for Nd isotope signature along profiles. For all profiles, deep soils are relatively consisted with bedrock value (ɛNd: 5.05). But in surface soils (0-600cm), unlike Sr isotope ratios that are significantly modified by marine aerosol input, Nd isotope ratios show similar decrease (to ɛNd:-10) and frequent fluctuations toward the surface, suggesting dust is the dominant source of Nd in these soils. This conclusion is further supported by REE and other trace element data. Thus, with a simplified two end-member model, Sahara dust contributes the Nd percentages in soils varying from 10.7% at the deepest profiles to 69.5% on surface, showing a significant amount of Nd on the surface soil came from dust source. The deep soil profiles are also characterized by the presence of Nd isotope spikes with negative values, suggesting dust signatures at depth. Such a feature could be related to the presence of a paleo-soil surface at the spike depth that was buried by later volcanic eruption. Both Nd and Sr isotopes hence show dust and volcanic inputs are important factors for soil developments on French Guadeloupe Island.

Progress towards Growth and Characterization of Rare-Earth Nanoparticles using the Inverse Micelle Method

NASA Astrophysics Data System (ADS)

Romero, Dulce G.; Ho, Pei-Chun

2008-03-01

Nano-sized particles and clusters have promising electrical, chemical, and magnetic properties as compared to the bulk materials. Due to their reduced dimensionality, it makes their physical properties significantly different from the bulk material. The nano-sized materials have great potential for technical applications, such as, magnetic information storage, imaging, medical devices, and magnetic refrigeration. In this report, we will present the preliminary results on the growth and characterization of rare-earth metallic nanoparticles of Gd and Nd synthesized by the inverse micelle method [1]. These results will be compared to the bulk properties of Gd and Nd, as well as, to those exhibited by metallic nanoparticles, such as Co (by inverse micelle), and Gd (by laser evaporation cluster source), which have been found to show superparamagnetic behavior, enhanced magnetization, and self-organization [2-4]. [1] X.M. Lin, et al. Langmuir. 14, 7140 (1998). [2] D.C. Douglass, et al. Phys. Rev. B. 47, 19 (1993). [3] C. Petit, et al. Advanced Materials. 10, 259 (1998). [4] J.P. Chen, et al. Phys. Rev. B. 51, 11527 (1995).

Growth of Nd doped (Lu, Gd)3(Ga, Al)5O12 single crystal by the micro pulling down method and their scintillation properties

NASA Astrophysics Data System (ADS)

Kamada, Kei; Kurosawa, Shunsuke; Yamaji, Akihiro; Shoji, Yasuhiro; Pejchal, Jan; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

2015-03-01

Nd 1 mol% doped (Lu, Gd)3(Ga, Al)5O12 (LGGAG) single crystals were grown by the micro-pulling down (μ-PD) method. Luminescence and scintillation properties such as absorption, excitation and emission spectra, light yield and decay time were evaluated. Nd1%:Lu3Al5O12 showed the highest light output of around 8200 photons/MeV among the grown crystals. Scintillation decay time of Nd:Y3Al5O12 was 1.32 μs (36%) 2.02 μs (64%). Nd:Lu3Ga3Al2O12 was relatively high dense scintillator of 7.38 g/cm3 with good light yield of 6800 photons/MeV and scintillation decay time of 0.20 μs (5%) 2.60 μs (95%).

Diode-pumped femtosecond mode-locked Nd, Y-codoped CaF2 laser

NASA Astrophysics Data System (ADS)

Zhu, Jiangfeng; Zhang, Lijuan; Gao, Ziye; Wang, Junli; Wang, Zhaohua; Su, Liangbi; Zheng, Lihe; Wang, Jingya; Xu, Jun; Wei, Zhiyi

2015-03-01

A passively mode-locked femtosecond laser based on an Nd, Y-codoped CaF2 disordered crystal was demonstrated. The Y3+-codoping in Nd : CaF2 markedly suppressed the quenching effect and improved the fluorescence quantum efficiency and emission spectra. With a fiber-coupled laser diode as the pump source, the continuous wave tuning range covering from 1042 to 1076 nm was realized, while the mode-locked operation generated 264 fs pulses with an average output power of 180 mW at a repetition rate of 85 MHz. The experimental results show that the Nd, Y-codoped CaF2 disordered crystal has potential in a new generation diode-pumped high repetition rate chirped pulse amplifier.

The Hadean upper mantle conundrum: evidence for source depletion and enrichment from Sm-Nd, Re-Os, and Pb isotopic compositions in 3.71 Gy boninite-like metabasalts from the Isua Supracrustal Belt, Greenland

NASA Astrophysics Data System (ADS)

Frei, Robert; Polat, Ali; Meibom, Anders

2004-04-01

Here we present Sm-Nd, Re-Os, and Pb isotopic data of carefully screened, least altered samples of boninite-like metabasalts from the Isua Supracrustal Belt (ISB, W Greenland)that characterize their mantle source at the time of their formation. The principal observations of this study are that by 3.7-3.8 Ga melt source regions existed in the upper mantle with complicated enrichment/depletion histories. Sm-Nd isotopic data define a correlation line with a slope corresponding to an age of 3.69 ± 0.18 Gy and an initial εNd value of +2.0 ± 4.7. This Sm-Nd age is consistent with indirect (but more precise) U-Pb geochronological estimates for their formation between 3.69-3.71 Ga. Relying on the maximum formation age of 3.71 Gy defined by the external age constraints, we calculate an average εNd [T = 3.71 Ga] value of +2.2 ± 0.9 (n = 18, 1σ) for these samples, which is indicative of a strongly depleted mantle source. This is consistent with the high Os concentrations, falling in the range between 1.9-3.4 ppb, which is similar to the estimated Os concentration for the primitive upper mantle. Re-Os isotopic data (excluding three outliers) yield an isochron defining an age of 3.76 ± 0.09 Gy (with an initial γOs value of 3.9 ± 1.2), within error consistent with the Sm-Nd age and the indirect U-Pb age estimates. An average initial γOs [T = 3.71 Ga] value of + 4.4 ± 1.2 (n = 8; 2σ) is indicative of enrichment of their source region during, or prior to, its melting. Thus, this study provides the first observation of an early Archean upper mantle domain with a distinctly radiogenic Os isotopic signature. This requires a mixing component characterized by time-integrated suprachondritic Re/Os evolution and a Os concentration high enough to strongly affect the Os budget of the mantle source; modern sediments, recycled basaltic crust, or the outer core do not constitute suitable candidates. At this point, the nature of the mantle or crustal component responsible for the radiogenic Os isotopic signature is not known. Compared with the Sm-Nd and Re-Os isotope systems, the Pb isotope systematics show evidence for substantial perturbation by postformational hydrothermal-metasomatic alteration processes accompanying an early Archean metamorphic event at 3510 ± 65 Ma and indicate that the U-Th-Pb system was partially opened to Pb-loss on a whole rock scale. Single stage mantle evolution models fail to provide a solution to the Pb isotopic data, which requires that a high-μ component was mixed with the depleted mantle component before or during the extrusion of the basalts. Relatively high 207Pb/204Pb ratios (compared to contemporaneous mantle), support the hypothesis that erosion products of the ancient terrestrial protocrust existed for several hundred My before recycling into the mantle before ∼3.7 Ga. Our results are broadly consistent with models favoring a time-integrated Hadean history of mantle depletion and with the existence of an early Hadean protocrust, the complement to the Hadean depleted mantle, which after establishment of subduction-like processes was, at least locally, recycled into the upper mantle before 3.7 Ga. Thus, already in the Hadean, the upper mantle seems to be characterized by geochemical heterogeneity on a range of length scales; one property that is shared with the modern upper mantle. However, a simple two component mixing scenario between depleted mantle and an enriched-, crustal component with a modern analogue can not account for the complicated and contradictory geochemical properties of this particular Hadean upper mantle source.

Lu-Hf AND Sm-Nd EVOLUTION IN LUNAR MARE BASALTS.

USGS Publications Warehouse

Unruh, D.M.; Stille, P.; Patchett, P.J.; Tatsumoto, M.

1984-01-01

Lu-Hf and Sm-Nd data for mare basalts combined with Rb-Sr and total REE data taken from the literature suggest that the mare basalts were derived by small ( less than equivalent to 10%) degrees of partial melting of cumulate sources, but that the magma ocean from which these sources formed was light REE and hf-enriched. Calculated source compositions range from lherzolite to olivine websterite. Nonmodal melting of small amounts of ilmenite ( less than equivalent to 3%) in the sources seems to be required by the Lu/Hf data. A comparison of the Hf and Nd isotopic characteristics between the mare basalts and terrestrial oceanic basalts reveals that the epsilon Hf/ epsilon Nd ratios in low-Ti mare basalts are much higher than in terrestrial ocean basalts.

Methods for the Determination of Chemical Substances in Marine and Estuarine Environmental Matrices - 2nd Edition

EPA Science Inventory

This NERL-Cincinnati publication, “Methods for the Determination of Chemical Substances in Marine and Estuarine Environmental Matrices - 2nd Edition” was prepared as the continuation of an initiative to gather together under a single cover a compendium of standardized laborato...

Rb-Sr and Sm-Nd Isotopic Studies of Lunar Green and Orange Glasses

NASA Technical Reports Server (NTRS)

Shih, C.-Y.; Nyquist, L. E.; Reese, Y.

2012-01-01

Lunar volcanic glassy beads have been considered as quenched basaltic magmas derived directly from deep lunar mantle during fire-fountaining eruptions [1]. Since these sub-mm size glassy melt droplets were cooled in a hot gaseous medium during free flight [2], they have not been subject to mineral fractionations. Thus, they represent primary magmas and are the best samples for the investigation of the lunar mantle. Previously, we presented preliminary Rb- Sr and Sm-Nd isotopic results for green and orange glassy samples from green glass clod 15426,63 and orange soil 74220,44, respectively [3]. Using these isotopic data, initial Sr-87/Sr-86 and Nd ratios for these pristine mare glass sources can be calculated from their respective crystallization ages previously determined by other age-dating techniques. These isotopic data were used to evaluate the mineralogy of the mantle sources. In this report, we analyzed additional glassy samples in order to further characterize isotopic signatures of their source regions. Also, we'll postulate a relationship between these two major mare basalt source mineralogies in the context of lunar magma ocean dynamics.

Mantle evolution on Mars: Constraints from Lu-Hf and Sm-Nd isotope systematics of SNC meteorites

NASA Astrophysics Data System (ADS)

Scherer, E. E.; Kurahashi, E.; Mezger, K.

2012-12-01

The long-lived 176Lu-176Hf and 147Sm-143Nd isotope systems are commonly employed to track the evolution of complementary mantle and crust reservoirs. The four elements involved are refractory and lithophile, and thus their relative abundances are not expected to have been changed by accretion or core formation. Subsequent silicate differentiation processes, however, e.g., the formation of crust by extraction of melts from the mantle, will fractionate Lu/Hf and Sm/Nd. This typically leaves a depleted mantle with higher Lu/Hf and Sm/Nd values than those of the undifferentiated, presumably chondritic parental reservoir. On the other hand, these same values in crustal rocks tend to be lower than those of their source. (Apparent exceptions are the Martian shergottites, which tend to have lower Lu/Hf as expected, but Sm/Nd higher than their presumed sources. Such decoupling of the two isotope systems may be explained by two-stage melting [e.g., 1, 5].) The ensuing chemical variability among secondary and later generation silicate reservoirs causes their isotopic compositions (e.g., 176Hf/177Hf and 143Nd/144Nd) to diverge from that of the bulk silicate planet over hundreds of millions of years. The resulting isotopic diversity preserved (SNC) meteorites is being used to constrain the differentiation history, melting mineralogy, and dynamics of the Martian mantle [e.g., 1-8]. However, interpretations based on the initial isotope compositions of Hf and Nd strongly depend on the accuracy of crystallization ages. The ages of shergottites in particular are debated (e.g., [3,4,7]). To resolve this issue and gain a better understanding of Martian mantle evolution, we are investigating the Lu-Hf and Sm-Nd systematics of bulk SNC meteorites and constructing internal (mineral) isochrons. Eleven bulk Martian meteorites (5 shergottites, 4 nakhlites, and 2 chassignites) were digested without prior leaching in high-pressure autoclaves for 5 days. Initial ɛ176Hf and ɛ143Nd values range from +49.0 to +51.3 and +34.7 to +47.8, respectively, for depleted shergottites, -13.3 to -17.4 and -6.3 to -6.5 for enriched shergottites, +1.8 to +14.5 and +13.4 to +15.6 for nakhlites, and +16.3 to +24.9 and +15.3 to +15.4 for chassignites. These data agree well with those of earlier studies [e.g., 2-8]. The initial ɛ143Nd of nakhlites and chassignites vary little relative to ɛ176Hf. The time-integrated 176Lu/177Hf and 147Sm/144Nd of all investigated source reservoirs form a narrow trend within the terrestrial MORB + OIB field, with the sources of nakhlites and chassignites located between those of depleted and enriched shergottites. Shergottites themselves display a large range of 147Sm/144Nd with higher values at a given 176Lu/177Hf relative to MORB + OIB. Evidence for both young (474-150 Ma) and old (> 4 Ga) shergottite ages will be evaluated and the effects of these disparate ages on models of silicate differentiation on Mars will be illustrated. [1] Borg et al., (1997) GCA 61:4915-4931. [2] Blichert-Toft J. et al. (1999) EPSL 173:25-39. [3] Bouvier A. et al. (2005) EPSL 240:221-233. [4] Bouvier A. et al. (2008) EPSL 266:105-124. [5] Debaille V. et al. (2008) EPSL 269:186-199. [6] Debaille V. et al. (2009) Nature Geosci. 2:548-552. [7] Shafer J. T. et al. (2010) GCA 74:7307-7328. [8] Lapen T. J. et al. (2010) Science 328:347-351.

Magnetocaloric effect in Gd1-x Ndx Zn2

NASA Astrophysics Data System (ADS)

Matsumoto, Keisuke T.; Hiraoka, Koichi

2017-09-01

The magnetization of Gd1-xNdxZn2 (0 < x ⩽ 1) was measured to study the effect of Nd substitution in GdZn2 with a Curie temperature of 85 K and a spin-reorientation transition temperature of 58 K on the magnetocaloric effect. The Nd counterpart NdZn2 shows antiferromagnetic order at 23 K. Samples of Gd1-xNdxZn2 (0 < x ⩽ 1) were prepared by the melt-growth method. In Nd-substituted systems, the anomaly due to spin-reorientation disappeared. For x ⩾ 0.6 , field-induced metamagnetic transitions were observed, indicating an antiferromagnetic ground state. This complex magnetism may originate from competition between ferromagnetic and antiferromagnetic interactions. Magnetic entropy change ΔSm was calculated based on the magnetization measurements. ΔSm was suppressed by Nd substitution for x values up to 0.6. For x = 1 (NdZn2), the maximum value of ΔSm was -9 J/K kg, which is almost the same as those of other Nd-based magnetocaloric materials.

Analysis of laser pumping and thermal effects based on element analysis

NASA Astrophysics Data System (ADS)

Cui, Li; Liu, Zhijia; Zhang, Yizhuo; Han, Juan

2018-03-01

Thermal effect is a plateau that limits the output of high-power, high beam quality laser, and thermal effects become worse with the increase of pump power. We can reduce the effects caused by thermal effects from pumping, laser medium shape, cooling method and other aspects. In this article, by using finite element analysis software, the thermal effects between Nd:Glass and Nd:YAG laser crystal was analyzed and compared. The causes of generation for thermal effects, and factors that influence the distribution in laser medium were analyzed, including the light source, the laser medium shape and the working mode. Nd:Glass is more suitable for low repetition frequency, high energy pulsed laser output, due to its large size, line width and so on, and Nd:YAG is more suitable for continue or high repetition rate laser output, due to its higher thermal conductivity.

Terahertz Spectroscopy and Global Analysis of the Rotational Spectrum of Doubly Deuterated Amidogen Radical ND2

NASA Astrophysics Data System (ADS)

Melosso, Mattia; Degli Esposti, Claudio; Dore, Luca

2017-11-01

The deuteration mechanism of molecules in the interstellar medium is still being debated. Observations of deuterium-bearing species in several astronomical sources represent a powerful tool to improve our understanding of the interstellar chemistry. The doubly deuterated form of the astrophysically interesting amidogen radical could be a target of detection in space. In this work, the rotational spectrum of the ND2 radical in its ground vibrational and electronic {X}2{B}1 state has been investigated between 588 and 1131 GHz using a frequency modulation millimeter/submillimeter-wave spectrometer. The ND2 molecule has been produced in a free-space glass absorption cell by discharging a mixture of ND3 and Ar. Sixty-four new transition frequencies involving J values from 2 to 5 and K a values from 0 to 4 have been measured. A global analysis including all the previous field-free pure rotational data has been performed, allowing for a more precise determination of a very large number of spectroscopic parameters. Accurate predictions of rotational transition frequencies of ND2 are now available from a few gigahertz up to several terahertz.

Geologically Controlled Isotope-Time Patterns Reveal Early Differentiation and Crust Formation Processes

NASA Astrophysics Data System (ADS)

Bennett, V. C.; Nutman, A. P.

2014-12-01

The mechanisms of continental crust production and evolution in the early Earth remain controversial, as are questions of the relative roles of early differentiation versus subsequent tectonic procssing in creating Earth's chemical signatures. Here we present geologic observations integrated with whole rock major, trace element and Sm-Nd isotopic signatures and combined with U-Pb and Lu-Hf isotopic compositions of zircon populations from the same rocks, from the most extensive early rock record comprising the 3.9 Ga to 3.6 Ga terranes of southwest Greenland. These data reveal repeated patterns of formation of juvenile TTG crust and associated mafic and ultramafic rocks in convergent margin settings followed by formation of more evolved granites [1]. Our new zircon Lu-Hf data from rare 3.6-3.7 Ga tonalites within the Itsaq Gneiss Complex, obtained from single component, non-migmatitic gneisses with simple zircon populations, limited within sample Hf isotopic variability and accurate U-Pb ages, now document extraction of juvenile tonalites from a near chondritic mantle source between 3.9 Ga and 3.6 Ga. The more evolved, granitic rocks in each area show slightly negative initial ɛHf in accord with crustal reworking of the older (3.8-3.9 Ga) gniesses. There is no evidence for Hadean material in the sources of the granitoids. The Hf isotope-time patterns are consistent with juvenile crust production from a mantle source that experienced only modest amounts of prior crustal extraction. They are distinct from those predicted by reprocessing of an enriched Hadean mafic crust, as has been proposed for this region [2] and for the source of the Hadean Jack Hills zircons [3]. The well-documented, time decreasing, positive 142Nd anomalies [e.g., 4] from these rocks are further evidence of crustal derivation from a convecting mantle source, rather than reworking of an enriched mafic lithosphere. The 143Nd isotopic -time patterns are more complex, reflecting the interplay between early Sm/Nd fractionation processes as required by the 142Nd data, juvenile crustal growth and in some cases geologic disturbance of the whole rock Sm-Nd system. [1] Nutman, et al, (2013) Amer. Jour. Sci. 313, 877-911. [2] Naeraa et al.. (2012) Nature 485, 627-631. [3] Kemp et al., (2010) EPSL 296, 45-56. [4] Bennett et al., (20070 Science 318, 1907.

Sr-Nd-Hf isotopic fingerprinting of transatlantic dust derived from North Africa

NASA Astrophysics Data System (ADS)

Zhao, Wancang; Balsam, William; Williams, Earle; Long, Xiaoyong; Ji, Junfeng

2018-03-01

Long-range transport of African dust plays an important role in understanding dust-climate relationships including dust source areas, dust pathways and associated atmospheric and/or oceanic processes. Clay-sized Sr-Nd-Hf isotopic compositions can be used as geochemical fingerprints to constrain dust provenance and the pathways of long-range transported mineral dust. We investigated the clay-sized Sr-Nd-Hf isotopic composition of surface samples along four transects bordering the Sahara Desert. The transects are from Mali, Niger/Benin/Togo, Egypt and Morocco. Our results show that the Mali transect on the West African Craton (WAC) produces lower εNd (εNd-mean = -16.38) and εHf (εHf-mean = -9.59) values than the other three transects. The Egyptian transect exhibits the lowest 87Sr/86Sr ratios (87Sr/86Srmean = 0.709842), the highest εHf (εHf-mean = -0.34) and εNd values of the four transects. Comparison of the clay-sized Sr-Nd-Hf isotopic values from our North African samples to transatlantic African dust collected in Barbados demonstrates that the dust's provenance is primarily the western Sahel and Sahara as well as the central Sahel. Summer emission dust is derived mainly from the western Sahel and Sahara regions. The source of transatlantic dust in spring and autumn is more varied than in the summer and includes dust not only from western areas, but also south central areas. Comparison of the Sr-Nd-Hf isotopic fingerprints between the source and sink of transatlantic dust also suggests that a northwestward shift in dust source occurs from the winter, through the spring and into the summer. The isotopic data we develop here provide another tool for discriminating changes in dust archives resulting from paleoenvironmental evolution of source regions.

Clay mineralogy, strontium and neodymium isotope ratios in the sediments of two High Arctic catchments (Svalbard)

NASA Astrophysics Data System (ADS)

Hindshaw, Ruth S.; Tosca, Nicholas J.; Piotrowski, Alexander M.; Tipper, Edward T.

2018-03-01

The identification of sediment sources to the ocean is a prerequisite to using marine sediment cores to extract information on past climate and ocean circulation. Sr and Nd isotopes are classical tools with which to trace source provenance. Despite considerable interest in the Arctic Ocean, the circum-Arctic source regions are poorly characterised in terms of their Sr and Nd isotopic compositions. In this study we present Sr and Nd isotope data from the Paleogene Central Basin sediments of Svalbard, including the first published data of stream suspended sediments from Svalbard. The stream suspended sediments exhibit considerable isotopic variation (ɛNd = -20.6 to -13.4; 87Sr / 86Sr = 0.73421 to 0.74704) which can be related to the depositional history of the sedimentary formations from which they are derived. In combination with analysis of the clay mineralogy of catchment rocks and sediments, we suggest that the Central Basin sedimentary rocks were derived from two sources. One source is Proterozoic sediments derived from Greenlandic basement rocks which are rich in illite and have high 87Sr / 86Sr and low ɛNd values. The second source is Carboniferous to Jurassic sediments derived from Siberian basalts which are rich in smectite and have low 87Sr / 86Sr and high ɛNd values. Due to a change in depositional conditions throughout the Paleogene (from deep sea to continental) the relative proportions of these two sources vary in the Central Basin formations. The modern stream suspended sediment isotopic composition is then controlled by modern processes, in particular glaciation, which determines the present-day exposure of the formations and therefore the relative contribution of each formation to the stream suspended sediment load. This study demonstrates that the Nd isotopic composition of stream suspended sediments exhibits seasonal variation, which likely mirrors longer-term hydrological changes, with implications for source provenance studies based on fixed end-members through time.

Large volume recycling of oceanic lithosphere over short time scales: geochemical constraints from the Caribbean Large Igneous Province

NASA Astrophysics Data System (ADS)

Hauff, F.; Hoernle, K.; Tilton, G.; Graham, D. W.; Kerr, A. C.

2000-01-01

Oceanic flood basalts are poorly understood, short-term expressions of highly increased heat flux and mass flow within the convecting mantle. The uniqueness of the Caribbean Large Igneous Province (CLIP, 92-74 Ma) with respect to other Cretaceous oceanic plateaus is its extensive sub-aerial exposures, providing an excellent basis to investigate the temporal and compositional relationships within a starting plume head. We present major element, trace element and initial Sr-Nd-Pb isotope composition of 40 extrusive rocks from the Caribbean Plateau, including onland sections in Costa Rica, Colombia and Curaçao as well as DSDP Sites in the Central Caribbean. Even though the lavas were erupted over an area of ˜3×10 6 km 2, the majority have strikingly uniform incompatible element patterns (La/Yb=0.96±0.16, n=64 out of 79 samples, 2σ) and initial Nd-Pb isotopic compositions (e.g. 143Nd/ 144Nd in=0.51291±3, ɛNdi=7.3±0.6, 206Pb/ 204Pb in=18.86±0.12, n=54 out of 66, 2σ). Lavas with endmember compositions have only been sampled at the DSDP Sites, Gorgona Island (Colombia) and the 65-60 Ma accreted Quepos and Osa igneous complexes (Costa Rica) of the subsequent hotspot track. Despite the relatively uniform composition of most lavas, linear correlations exist between isotope ratios and between isotope and highly incompatible trace element ratios. The Sr-Nd-Pb isotope and trace element signatures of the chemically enriched lavas are compatible with derivation from recycled oceanic crust, while the depleted lavas are derived from a highly residual source. This source could represent either oceanic lithospheric mantle left after ocean crust formation or gabbros with interlayered ultramafic cumulates of the lower oceanic crust. High 3He/ 4He in olivines of enriched picrites at Quepos are ˜12 times higher than the atmospheric ratio suggesting that the enriched component may have once resided in the lower mantle. Evaluation of the Sm-Nd and U-Pb isotope systematics on isochron diagrams suggests that the age of separation of enriched and depleted components from the depleted MORB source mantle could have been ≤500 Ma before CLIP formation and interpreted to reflect the recycling time of the CLIP source. Mantle plume heads may provide a mechanism for transporting large volumes of possibly young recycled oceanic lithosphere residing in the lower mantle back into the shallow MORB source mantle.

The Northwest Africa 8159 martian meteorite: Expanding the martian sample suite to the early Amazonian

NASA Astrophysics Data System (ADS)

Herd, Christopher D. K.; Walton, Erin L.; Agee, Carl B.; Muttik, Nele; Ziegler, Karen; Shearer, Charles K.; Bell, Aaron S.; Santos, Alison R.; Burger, Paul V.; Simon, Justin I.; Tappa, Michael J.; McCubbin, Francis M.; Gattacceca, Jérôme; Lagroix, France; Sanborn, Matthew E.; Yin, Qing-Zhu; Cassata, William S.; Borg, Lars E.; Lindvall, Rachel E.; Kruijer, Thomas S.; Brennecka, Gregory A.; Kleine, Thorsten; Nishiizumi, Kunihiko; Caffee, Marc W.

2017-12-01

Northwest Africa (NWA) 8159 is an augite-rich shergottite, with a mineralogy dominated by Ca-, Fe-rich pyroxene, plagioclase, olivine, and magnetite. NWA 8159 crystallized from an evolved melt of basaltic composition under relatively rapid conditions of cooling, likely in a surface lava flow or shallow sill. Redox conditions experienced by the melt shifted from relatively oxidizing (with respect to known Martian lithologies, ∼QFM) on the liquidus to higher oxygen fugacity (∼QFM + 2) during crystallization of the groundmass, and under subsolidus conditions. This shift resulted in the production of orthopyroxene and magnetite replacing olivine phenocryst rims. NWA 8159 contains both crystalline and shock-amorphized plagioclase (An50-62), often observed within a single grain; based on known calibrations we bracket the peak shock pressure experienced by NWA 8159 to between 15 and 23 GPa. The bulk composition of NWA 8159 is depleted in LREE, as observed for Tissint and other depleted shergottites; however, NWA 8159 is distinct from all other martian lithologies in its bulk composition and oxygen fugacity. We obtain a Sm-Nd formation age of 2.37 ± 0.25 Ga for NWA 8159, which represents an interval in Mars geologic time which, until recently, was not represented in the other martian meteorite types. The bulk rock 147Sm/144Nd value of 0.37 ± 0.02 is consistent with it being derived directly from its source and the high initial ε143Nd value indicates this source was geochemically highly depleted. Cr, Nd, and W isotopic compositions further support a unique mantle source. While the rock shares similarities with the 2.4-Ga NWA 7635 meteorite, there are notable distinctions between the two meteorites that suggest differences in mantle source compositions and conditions of crystallization. Nevertheless, the two samples may be launch-paired. NWA 8159 expands the known basalt types, ages and mantle sources within the Mars sample suite to include a second igneous unit from the early Amazonian.

Low temperature diffusion process using rare earth-Cu eutectic alloys for hot-deformed Nd-Fe-B bulk magnets

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

Akiya, T., E-mail: akiya.takahiro@nims.go.jp; Sepehri-Amin, H.; Ohkubo, T.

2014-05-07

The low temperature grain boundary diffusion process using RE{sub 70}Cu{sub 30} (RE = Pr, Nd) eutectic alloy powders was applied to sintered and hot-deformed Nd-Fe-B bulk magnets. Although only marginal coercivity increase was observed in sintered magnets, a substantial enhancement in coercivity was observed when the process was applied to hot-deformed anisotropic bulk magnets. Using Pr{sub 70}Cu{sub 30} eutectic alloy as a diffusion source, the coercivity was enhanced from 1.65 T to 2.56 T. The hot-deformed sample expanded along c-axis direction only after the diffusion process as RE rich intergranular layers parallel to the broad surface of the Nd{sub 2}Fe{sub 14}B are thickened inmore » the c-axis direction.« less

Second-order spherical optoelectronic detector for 3D multi-particles wave emission and propagation in space time domains

NASA Astrophysics Data System (ADS)

Romano, Francesco; Cimmino, Rosario F.

2017-09-01

This paper concerns a feasibility study on a 2nd order spherical, or three-dimensional, angular momentum and linear momentum detector for photonic radiation applications. It has been developed in order to obtain a paraxial approximation of physical events observed under Coulomb gauge condition, which is essential to compute both the longitudinal and transverse rotational components of the observed 3-D vortex field, generally neglected by conventional detection systems under current usage. Since light and laser beams are neither full transversal or rotational phenomena, to measure directly and in the same time both the energy, mainly not-rotational, related to the relevant part of the linear momentum and the potential solenoidal energy (vortex), related to the angular momentum, 2nd order spherical, or 3-D, detector techniques are required. In addition, direct 2nd order measure techniques enable development of TEM + DEM [17] studies, therefore allowing for monochromatic complex wave detection with a paraxial accuracy in the relativistic time-space domain. Light and optic or Electromagnetic 2nd order 3-D AnM energy may usefully be used in tre-dimensional optical TEM, noTEM, DEM vortex or laser communications The paper illustrates an innovative quadratic order 3-D spherical model detector applied to directly measure a light source power spectrum and compares the performances of this innovative technique with those obtained with a traditional 1st order system. Results from a number of test experiments conducted in cooperation with INAF Observatories of ArcetriFlorence and Medicina-Bologna (Italy), and focused on telescopic observations of the inter-stellar electromagnetic radiations, are also summarized. The innovative quadratic-order spherical detector turns out to be optimal for optical and/or radio telescopes application, optical and optoelectronic sensors development and gravitational wave 2nd order detectors implementation. Although the proposed method is very innovative, it shows a very good adherence with results obtained with the conventional techniques in current usage.

Sources and processes affecting the distribution of dissolved Nd isotopes and concentrations in the West Pacific

NASA Astrophysics Data System (ADS)

Behrens, Melanie K.; Pahnke, Katharina; Schnetger, Bernhard; Brumsack, Hans-Jürgen

2018-02-01

In the Atlantic, where deep circulation is vigorous, the dissolved neodymium (Nd) isotopic composition (expressed as ɛNd) is largely controlled by water mass mixing. In contrast, the factors influencing the ɛNd distribution in the Pacific, marked by sluggish circulation, is not clear yet. Indication for regional overprints in the Pacific is given based on its bordering volcanic islands. Our study aims to clarify the impact and relative importance of different Nd sources (rivers, volcanic islands), vertical (bio)geochemical processes and lateral water mass transport in controlling dissolved ɛNd and Nd concentration ([Nd]) distributions in the West Pacific between South Korea and Fiji. We find indication for unradiogenic continental input from South Korean and Chinese rivers to the East China Sea. In the tropical West Pacific, volcanic islands supply Nd to surface and subsurface waters and modify their ɛNd to radiogenic values of up to +0.7. These radiogenic signatures allow detailed tracing of currents flowing to the east and differentiation from westward currents with open ocean Pacific ɛNd composition in the complex tropical Pacific zonal current system. Modified radiogenic ɛNd of West Pacific intermediate to bottom waters upstream or within our section also indicates non-conservative behavior of ɛNd due to boundary exchange at volcanic island margins, submarine ridges, and with hydrothermal particles. Only subsurface to deep waters (3000 m) in the open Northwest Pacific show conservative behavior of ɛNd. In contrast, we find a striking correlation of extremely low (down to 2.77 pmol/kg Nd) and laterally constant [Nd] with the high-salinity North and South Pacific Tropical Water, indicating lateral transport of preformed [Nd] from the North and South Pacific subtropical gyres into the study area. This observation also explains the previously observed low subsurface [Nd] in the tropical West Pacific. Similarly, Western South Pacific Central Water, Antarctic Intermediate Water, and Lower Circumpolar Deep Water in the southern and equatorial West Pacific are marked by vertically and laterally almost invariant [Nd] indicating a dominance of conservative behavior of [Nd]. In contrast, Central and Intermediate Water in the North West Pacific are characterized by increasing [Nd] with depth reflecting Nd release from particles. Overall, our data demonstrate a dominant lateral transport control on [Nd] distributions and clear non-conservative modification of ɛNd in the West Pacific. The latter affords tracing of surface and subsurface zonal transport in the tropical Pacific, but prevents the use of ɛNd as strictly conservative tracer of the major meridionally circulating water masses in the West Pacific between 15°S and 28°N.

New data for paleoprotherozoic PGE-bearing anorthosite of Kandalaksha massif (Baltic shield): U-Pb and Sm-Nd ages

NASA Astrophysics Data System (ADS)

Steshenko, Ekaterina; Bayanova, Tamara; Serov, Pavel

2015-04-01

The aims of this researches were to study the isotope U-Pb age of zircon and rutile and Sm-Nd (rock forming and sulphide minerals) on Kandalaksha anorthosite massif due to study of polimetamorphic history. In marginal zone firstly have been obtained the presence of sulphide mineralization with PGE (Chashchin, Petrov , 2013). Kandalaksha massif is located in the N-E part of Baltic shield and consists of three parts. Marginal zone (mesocratic metanorite) lies at the base of the massif. Main zone is composed of leucocratic metagabbro. The upper zone is alteration of mataanorthosite and leucocratic metagabbro. All rocks were subjected to granulate polymetamorphism. Two fractions of single grains from anorthosite of the massif gave precise U-Pb age, which is equal to 2450± 3 Ma. Leucocratic gabbro-norite were dated by U-Pb method, with age up to 2230 ± 10 Ma. This age reflects the time of granulite metamorphism according to data of (Mitrofanov, Nirovich, 2003). Two fractions of rutile have been analyzed by U-Pb method and reflect age of 1700 ± 10 Ma. It is known that the closure temperature of U-Pb system rutile is 400-450 ° C (Mezger et.al., 1989), thus cooling processes of massif rocks to these temperatures was about 1.7 Ga. These data reflect one of the stages of metamorphic alteration of the massif. Three stages of metamorphism are distinguished by Sm-Nd method. Isotope Sm-Nd dating on Cpx-WR line gives the age of 2311 Ma which suggested of high pressure granulite metamorphism. Moreover Cpx-Pl line reflect the age 1908 Ma of low pressure granulite metamorphism. Also two-points (Grt-Rt) Sm-Nd isochrone yield the age 1687 Ma of the last metamorphic alterations in Kandalaksha anorthosite massif. Model Sm-Nd age of the leucocratic gabbro-norite is 2796 Ma with positive ɛNd (+0.32). It means that the source of gabbro-norite was mantle reservoir. All investigations are devoted to memory of academician PAS F. MItrofanov which was a leader of scientific school for geology, geochemistry and metallogenesis of ore deposits. The studies are contribution by RFBR OFI-M 13-05-12055, 13-05-00493, Department of Earth Sciences RAS (programs 2 and 4), and IGCP-SIDA 599.

Thermal effects on cavity stability of chromium- and neodymium-doped gadolinium scandium gallium garnet laser under solar-simulator pumping

NASA Technical Reports Server (NTRS)

Kim, Kyong H.; Venable, Demetrius D.; Brown, Lamarr A.; Lee, Ja H.

1991-01-01

Results are presented on testing a Cr- and Nd-codoped Gd-Sc-Ga-garnet (Cr:Nd:GSGG) crystal and a Nd:YAG crystal (both of 3.2 mm diam and 76-mm long) for pulsed and CW laser operations using a flashlamp and solar simulator as pumping sources. Results from experiments with the flashlamp show that, at pulse lengths of 0.11, 0.28, and 0.90 ms, the slope efficiency of the Cd:Nd:GSGG crystal was higher than that of the Nd:YAG crystal and increased with pulse width. With the solar simulator, however, the CW laser operation of the Cr:Nd:GSGG crystal was limited to intensities not greater than 1500 solar constants, while the Nd:YAG laser successfully performed for all pump beam intensities available. It was found that the exposure for several minutes of the Cr:Nd:GSGG crystal to pump beam intensity of 3000 solar constants led to its damage by thermal cracking, indicating that a better solar-pumped CW laser performance may be difficult to realize with rod geometry.

Biologically recycled continental iron is a major component in banded iron formations

PubMed Central

Li, Weiqiang; Beard, Brian L.; Johnson, Clark M.

2015-01-01

Banded iron formations (BIFs) record a time of extensive Fe deposition in the Precambrian oceans, but the sources and pathways for metals in BIFs remain controversial. Here, we present Fe- and Nd-isotope data that indicate two sources of Fe for the large BIF units deposited 2.5 billion y ago. High-εNd and -δ56Fe signatures in some BIF samples record a hydrothermal component, but correlated decreases in εNd- and δ56Fe values reflect contributions from a continental component. The continental Fe source is best explained by Fe mobilization on the continental margin by microbial dissimilatory iron reduction (DIR) and confirms for the first time, to our knowledge, a microbially driven Fe shuttle for the largest BIFs on Earth. Detailed sampling at various scales shows that the proportions of hydrothermal and continental Fe sources were invariant over periods of 100–103 y, indicating that there was no seasonal control, although Fe sources varied on longer timescales of 105–106 y, suggesting a control by marine basin circulation. These results show that Fe sources and pathways for BIFs reflect the interplay between abiologic (hydrothermal) and biologic processes, where the latter reflects DIR that operated on a basin-wide scale in the Archean. PMID:26109570

Biologically recycled continental iron is a major component in banded iron formations.

PubMed

Li, Weiqiang; Beard, Brian L; Johnson, Clark M

2015-07-07

Banded iron formations (BIFs) record a time of extensive Fe deposition in the Precambrian oceans, but the sources and pathways for metals in BIFs remain controversial. Here, we present Fe- and Nd-isotope data that indicate two sources of Fe for the large BIF units deposited 2.5 billion y ago. High-εNd and -δ(56)Fe signatures in some BIF samples record a hydrothermal component, but correlated decreases in εNd- and δ(56)Fe values reflect contributions from a continental component. The continental Fe source is best explained by Fe mobilization on the continental margin by microbial dissimilatory iron reduction (DIR) and confirms for the first time, to our knowledge, a microbially driven Fe shuttle for the largest BIFs on Earth. Detailed sampling at various scales shows that the proportions of hydrothermal and continental Fe sources were invariant over periods of 10(0)-10(3) y, indicating that there was no seasonal control, although Fe sources varied on longer timescales of 10(5)-10(6) y, suggesting a control by marine basin circulation. These results show that Fe sources and pathways for BIFs reflect the interplay between abiologic (hydrothermal) and biologic processes, where the latter reflects DIR that operated on a basin-wide scale in the Archean.

Luminescence mechanism and energy transfer in doubly-doped BaY2F8:Tm,Nd VUV scintillator

NASA Astrophysics Data System (ADS)

Pejchal, J.; Nikl, M.; Moretti, F.; Vedda, A.; Fukuda, K.; Kawaguchi, N.; Yanagida, T.; Yokota, Y.; Yoshikawa, A.

2010-11-01

Doubly-doped BaY2F8:Tm,Nd scintillation crystals were grown by modified micro-pulling-down method. Nd co-doping was chosen to enhance the energy transfer from the host lattice to the Nd3+ luminescence center via the 5d-levels of Tm3+, due to the overlap of Tm3+ 5d-4f emission spectrum with the Nd3+ 4f-5d absorption. The energy transfer was clearly evidenced in the BaY2F8:Tm,Nd. This process is not complicated by an energy migration to killer centers and/or cross-relaxation. The radioluminescence process is complicated by an energy transfer from the host lattice exciton states to the lower f-levels of Tm3+ ion.

Geochemistry, Nd-Pb Isotopes, and Pb-Pb Ages of the Mesoproterozoic Pea Ridge Iron Oxide-Apatite–Rare Earth Element Deposit, Southeast Missouri

USGS Publications Warehouse

Ayuso, Robert A.; Slack, John F.; Day, Warren C.; McCafferty, Anne E.

2016-01-01

Iron oxide-apatite and iron oxide-copper-gold deposits occur within ~1.48 to 1.47 Ga volcanic rocks of the St. Francois Mountains terrane near a regional boundary separating crustal blocks having contrasting depleted-mantle Sm-Nd model ages (TDM). Major and trace element analyses and Nd and Pb isotope data were obtained to characterize the Pea Ridge deposit, improve identification of exploration targets, and better understand the regional distribution of mineralization with respect to crustal blocks. The Pea Ridge deposit is spatially associated with felsic volcanic rocks and plutons. Mafic to intermediate-composition rocks are volumetrically minor. Data for major element variations are commonly scattered and strongly suggest element mobility. Ratios of relatively immobile elements indicate that the felsic rocks are evolved subalkaline dacite and rhyolite; the mafic rocks are basalt to basaltic andesite. Granites and rhyolites display geochemical features typical of rocks produced by subduction. Rare earth element (REE) variations for the rhyolites are diagnostic of rocks affected by hydrothermal alteration and associated REE mineralization. The magnetite-rich rocks and REE-rich breccias show similar REE and mantle-normalized trace element patterns.Nd isotope compositions (age corrected) show that: (1) host rhyolites have ɛNd from 3.44 to 4.25 and TDM from 1.51 to 1.59 Ga; (2) magnetite ore and specular hematite rocks display ɛNd from 3.04 to 4.21 and TDM from 1.6 to 1.51 Ga, and ɛNd from 2.23 to 2.81, respectively; (3) REE-rich breccias have ɛNd from 3.04 to 4.11 and TDM from 1.6 to 1.51 Ga; and (4) mafic to intermediate-composition rocks range in ɛNd from 2.35 to 3.66 and in TDM from 1.66 to 1.56. The ɛNd values of the magnetite and specular hematite samples show that the REE mineralization is magmatic; no evidence exists for major overprinting by younger, crustal meteoric fluids, or by externally derived Nd. Host rocks, breccias, and magnetite ore shared a common origin from a similar source.Lead isotope ratios are diverse: (1) host rhyolite has 206Pb/204Pb from 24.261 to 50.091; (2) Pea Ridge and regional galenas have 206Pb/204Pb from 16.030 to 33.548; (3) REE-rich breccia, magnetite ore, and specular hematite rock are more radiogenic than galena; (4) REE-rich breccias have high 206Pb/204Pb (38.122–1277.61) compared to host rhyolites; and (5) REE-rich breccias are more radiogenic than magnetite ore and specular-hematite rock, having 206Pb/204Pb up to 230.65. Radiogenic 207Pb/206Pb age estimates suggest the following: (1) rhyolitic host rocks have ages of ~1.50 Ga, (2) magnetite ore is ~1.44 Ga, and (3) REE-rich breccias are ~1.48 Ga. These estimates are broadly consistent and genetically link the host rhyolite, REE-rich breccia, and magnetite ore as being contemporaneous.Alteration style and mineralogical or textural distinctions among the magnetite-rich rocks and REE-rich breccias do not correlate with different isotopic sources. In our model, magmatic fluids leached metals from the coeval felsic rocks (rhyolites), which provided the metal source reflected in the compositions of the REE-rich breccias and mineralized rocks. This model allows for the likelihood of contributions from other genetically related felsic and intermediate to more mafic rocks stored deeper in the crust. The deposit thus records an origin as a magmatic-hydrothermal system that was not affected by Nd and Pb remobilization processes, particularly if these processes also triggered mixing with externally sourced metal-bearing fluids. The Pea Ridge deposit was part of a single, widespread, homogeneous mixing system that produced a uniform isotopic composition, thus representing an excellent example of an igneous-dominated system that generated coeval magmatism and REE mineralization. Geochemical features suggest that components in the Pea Ridge deposit originated from sources in an orogenic margin. Basaltic magmatism produced by mantle decompression melting provided heat for extracting melts from the middle or lower crust. Continual addition of mafic magmas to the base of the subcontinental lithosphere, in a back-arc setting, remelted calc-alkaline rocks enriched in metals that were stored in the crust.The St. Francois Mountains terrane is adjacent to the regional TDM line (defined at a value of 1.55 Ga) that separates ~1600 Ma basement to the west, from younger basements to the east. Data for Pea Ridge straddle the TDM values proposed for the line. The Sm-Nd isotope system has been closed since formation of the deposit and the original igneous signatures have not been affected by cycles of alteration or superimposed mineralizing events. No evidence exists for externally derived Nd or Sm. The source region for metals within the Pea Ridge deposit had a moderate compositional variation and the REE-rich breccias and mineralized rocks are generally isotopically homogeneous. The Pea Ridge deposit thus constitutes a distinctive isotopic target for use as a model in identifying other mineralized systems that may share the same metal source in the St. Francois Mountains terrane and elsewhere in the eastern Granite-Rhyolite province.

Comparison between a CO2 and a Nd-YAG laser with fibertom system in the treatment of frenulum breve

NASA Astrophysics Data System (ADS)

Wozniak, Jakub; Dydowicz, Piotr; Jedrzejczak, Piotr; Opala, Tomasz; Wilczak, Maciej; Pisarska-Krawczyk, Magdalena; Pisarski, Tadeusz

1997-10-01

The study showed the treatment of frenulum breve in 24 patients. Nine of them were treated with CO2 and eight ones with Nd:YAG lasers. In seven males the classical surgical procedures were done. All patients were treated in Department of Reproduction, Institute of Gynecology and Obstetrics, Karol Marcinkowski School of Medical Sciences, Poznan, Poland between March 1995 and September 1996. All procedures were collected successful and no serious complications were observed. The all males are still under control in our department. The use of lasersurgery is the safe and efficient method in treatment of frenulum breve. Lasersurgery may be conducting as the out-patient procedure or one-day surgery because of possibility of NLA and local anesthesia. The use of CO2 seems to be the better method than Nd:YAG laser with fibertom system in treatment of frenulum breve because of shorter time of healing. There are no differences between hemostasis achieved by CO2 and Nd:YAG lasers. The incision effect is the same, when CO2 and Nd:YAG laser with fibertom system are used.

Novel hydrogen decrepitation behaviors of (La, Ce)-Fe-B strips

NASA Astrophysics Data System (ADS)

Jin, Jiaying; Bai, Guohua; Zhang, Yujing; Peng, Baixing; Liu, Yongsheng; Ma, Tianyu; Yan, Mi

2018-05-01

La and Ce substitution for Nd in the 2:14:1-type sintered magnet is of commercial interest to reduce the material cost and to balance the utilization of rare earth (RE) sources. As hydrogen decrepitation (HD) is widely utilized to prepare the magnetic powders during magnets fabrication, incorporating La and Ce into the Nd-Fe-B permanent magnets, however, may exert complex influences on the decrepitation behavior. In the present work, through a comparative study of the HD behaviors between the (La, Ce)-Fe-B strips and the conventional Nd-Fe-B ones, we find that similar to the Nd-Fe-B system, increasing hydrogen pressures from 2.5 to 5.5 MPa do not break the 2:14:1 tetragonal structure of (La, Ce)-Fe-B strips. The enhanced hydrogen absorption behaviors are observed with increasing pressure, which are still inferior to that of the Nd-Fe-B strips. This should be ascribed to the higher oxygen affinity of La and Ce than that of Nd, leading to the decreased amount of active RE-rich phase and limited hydrogen diffusion channel. As a result, the hydrogen absorption of 2:14:1 matrix phase is significantly suppressed, dramatically weakening the exothermic effect. This finding suggests that La and Ce with stable 2:14:1 tetragonal structure upon HD process are promising alternatives for Nd, despite that more precise oxygen control is necessary for the microstructure modification and magnetic performance enhancement of (La, Ce)-Fe-B sintered magnets.

VUV and UV Sources and Spectroscopic Applications

DTIC Science & Technology

1991-12-01

Toyoshima, H . Onuki , N. Washida, and T. Ibuki, J. Chem. Phys. 85, 4867 (1986). 17 J. Heidberg, R. Daghighi-Ruhi. H . von Weyssenhoff. and A. Habekost, Mat...20.0 1Sp r 3r 33867.2±0.39 14.3658 6.37±0.105 13.0±10.09 N.D. 18pa 31: h h h h h 16pm 3T8 33938.4±0.3 15.435 6.30±0.15 N.D. N.D. 19pa 3E 33987.0±0.3...photodissociation often results in the rupture of the weakest bond in the molecule, which may yield, for example, ABC + h -- AB + C (2.3) rather than the desired

A fundamental mode Nd:GdVO4 laser pumped by a large aperture 808 nm VCSEL

NASA Astrophysics Data System (ADS)

Hao, Y. Q.; Ma, J. L.; Yan, C. L.; Liu, G. J.; Ma, X. H.; Gong, J. F.; Feng, Y.; Wei, Z. P.; Wang, Y. X.; Zhao, Y. J.

2013-05-01

A fundamental mode Nd:GdVO4 laser pumped by a vertical cavity surface emitting laser (VCSEL) is experimentally demonstrated. The VCSEL has a circular output-beam which makes it easier for it to be directly coupled to a Nd:GdVO4 microcrystal. In our research, a large aperture 808 nm VCSEL, with a multi-ring-shaped aperture (MRSA) and an almost Gaussian-shaped far-field profile, is used as the pumping source. Experimental results for the Nd:GdVO4 laser pumped by the VCSEL are presented. The maximum output peak power of 0.754 W is obtained under a pump peak power of 1.3 W, and the corresponding opto-optic conversion efficiency is 58.1%. The average slope efficiency is 65.8% from the threshold pump power of 0.2 W to the pump power of 1.3 W. The laser beam quality factors are measured to be {M}x2=1.2 0 and {M}y2=1.1 5.

Preparation and Characterization of Zirconia-Coated Nanodiamonds as a Pt Catalyst Support for Methanol Electro-Oxidation

PubMed Central

Lu, Jing; Zang, Jianbing; Wang, Yanhui; Xu, Yongchao; Xu, Xipeng

2016-01-01

Zirconia-coated nanodiamond (ZrO2/ND) electrode material was successfully prepared by one-step isothermal hydrolyzing from ND-dispersed ZrOCl2·8H2O aqueous solution. High-resolution transmission electron microscopy reveals that a highly conformal and uniform ZrO2 shell was deposited on NDs by this simple method. The coating obtained at 90 °C without further calcination was mainly composed of monoclinic nanocrystalline ZrO2 rather than common amorphous Zr(OH)4 clusters. The ZrO2/NDs and pristine ND powder were decorated with platinum (Pt) nanoparticles by electrodeposition from 5 mM chloroplatinic acid solution. The electrochemical studies indicate that Pt/ZrO2/ND catalysts have higher electrocatalytic activity and better stability for methanol oxidation than Pt/ND catalysts in acid. PMID:28335361

Recent Progress in the Development of Neodymium Doped Ceramic Yttria

NASA Technical Reports Server (NTRS)

Prasad, Narasimha S.; Edwards, Chris; Trivedi, Sudhir B.; Kutcher, Susan; Wang, Chen-Chia; Kim, Joo-Soo; Hommerich, Uwe; Shukla, Vijay; Sadangi, Rajendra; Kear, Bernard

2007-01-01

Solid-state lasers play a significant role in providing the technology necessary for active remote sensing of the atmosphere. Neodymium doped yttria (Nd:Y2O3) is considered to be an attractive material due to its possible lasing wavelengths of aprrox.914 nm and approx.946 nm for ozone profiling. These wavelengths when frequency tripled can generate UV light at approx.305 nm and approx.315 nm, which is particularly useful for ozone sensing using differential absorption lidar technique. For practical realization of space based UV transmitter technology, ceramic Nd:Y2O3 material is considered to possess great potential. A plasma melting and quenching method has been developed to produce Nd3+ doped powders for consolidation into Nd:Y2O3 ceramic laser materials. This far-from-equilibrium processing methodology allows higher levels of rare earth doping than can be achieved by equilibrium methods. The method comprises of two main steps: (a) plasma melting and quenching to generate dense, and homogeneous doped metastable powders, (b) pressure assisted consolidation of these powders by hot isostatic pressing to make dense nanocomposite ceramics. Using this process, several 1" x 1" ceramic cylinders have been produced. The infrared transmission of undoped Y2O3 ceramics was as high as approx.75% without anti-reflection coating. In the case of Nd:Y2O3 ceramics infrared transmission values of approx.50% were achieved. Furthermore, Nd:Y2O3 samples with dopant concentrations of up to approx.2 at. % were prepared without significant emission quenching.

Synthesis and characterization of iron based superconductor Nd-1111

NASA Astrophysics Data System (ADS)

Alborzi, Z.; Daadmehr, V.

2018-06-01

Polycrystalline sample of NdFeAsO0.8F0.2 was prepared by one-step solid-state reaction method. The structural and electrical properties of sample were characterized through XRD pattern and the 4-probe method. The critical temperature was obtained at 56 K. The crystal structure was tetragonal with P4/nmm:2 symmetry group.

2nd-Order CESE Results For C1.4: Vortex Transport by Uniform Flow

NASA Technical Reports Server (NTRS)

Friedlander, David J.

2015-01-01

The Conservation Element and Solution Element (CESE) method was used as implemented in the NASA research code ez4d. The CESE method is a time accurate formulation with flux-conservation in both space and time. The method treats the discretized derivatives of space and time identically and while the 2nd-order accurate version was used, high-order versions exist, the 2nd-order accurate version was used. In regards to the ez4d code, it is an unstructured Navier-Stokes solver coded in C++ with serial and parallel versions available. As part of its architecture, ez4d has the capability to utilize multi-thread and Messaging Passage Interface (MPI) for parallel runs.

Structural and optical properties of nano-sized K3Nd(PO4)2:Yb3+ orthophosphate.

PubMed

Mizer, D; Macalik, L; Tomaszewski, P E; Lisiecki, R; Godlewska, P; Matraszek, A; Szczygieł, I; Zawadzki, M; Hanuza, J

2009-09-01

Nanocrystals of tripotassium neodymium bis-phosphate(V) doped with ytterbium ions, K3Nd(PO4)2: Yb3+, were synthesized by Pechini method. The obtained grains, having an average size of about 40 nm, were characterised by X-ray, electron microscopic, electron absorption, luminescence and IR studies. Moreover, fluorescence decay studies were carried out at room temperature. The energy transfer from the Nd3+ to Yb3+ was described and discussed. The results were compared to those of the K3Nd(PO4)2 bulk crystal.

Sm-Nd and Rb-Sr Ages for MIL 05035: Implications for Surface and Mantle Sources

NASA Technical Reports Server (NTRS)

Nyquist, L. E.; Shih, C-Y.; Reese, Y. D.

2007-01-01

The Sm-Nd and Rb-Sr ages and also the initial Nd and Sr isotopic compositions of MIL 05035 are the same as those of A-881757. Comparing the radiometric ages of these meteorites to lunar surface ages as modeled from crater size-frequency distributions as well as the TiO2 abundances and initial Sr-isotopic compositions of other basalts places their likely place of origin as within the Australe or Humboldtianum basins. If so, a fundamental west-east lunar asymmetry in compositional and isotopic parameters that likely is due to the PKT is implied.

Variable sources for Cretaceous to recent HIMU and HIMU-like intraplate magmatism in New Zealand

NASA Astrophysics Data System (ADS)

van der Meer, Q. H. A.; Waight, T. E.; Scott, J. M.; Münker, C.

2017-07-01

Continental intraplate magmas with isotopic affinities similar to HIMU are identified worldwide. Involvement of an asthenospheric HIMU or HIMU-like source is contested because the characteristic radiogenic Pb compositions coupled with unradiogenic Sr and intermediate Nd and Hf compositions can also result from in-situ ingrowth in metasomatised lithospheric mantle. Sr-Nd-Pb-Hf isotopic compositions of late Cretaceous lamprophyre dikes from Westland, New Zealand, provide new insights into the formation of a HIMU-like alkaline intraplate magmatic province under the Zealandia continent. The oldest (102-100 Ma) calc-alkaline lamprophyres are compositionally similar to the preceding arc-magmatism (206Pb/204Pb(i) = 18.6, 207Pb/204Pb(i) = 15.62, 208Pb/204Pb(i) = 38.6, 87Sr/86Sr(i) = 0.7063-0.7074, εNd(i) = -2.1 - +0.1 and εHf(i) = -0.2 - +2.3) and are interpreted as melts originating from subduction-modified lithosphere. Alkaline dikes erupted on the inboard Gondwana margin shortly after cessation of subduction (92-84 Ma) have heterogeneous isotopic properties: 206Pb/204Pb(i) = 18.7 to 19.4, 207Pb/204Pb(i) = 15.60 to 15.65, 208Pb/204Pb(i) = 38.6 to 39.4, 87Sr/86Sr(i) = 0.7031 to 0.7068, εNd(i) = +4.5 to +8.0 and εHf(i) = +5.1 to +8.0. Melt compositions point to an amphibole-bearing spinel facies lithospheric mantle source enriched by metasomatism that introduced, amongst many elements, U + Th which lead to rapid ingrowth to HIMU-like compositions. Importantly, this HIMU-like source enrichment appears to have completely originated from the complex local subduction history. A coeval episode of alkaline magmatism (mainly 98-82 Ma) occurred outboard of Gondwana's former active margin and on the Hikurangi oceanic plateau (accreted to Zealandia in the Early Cretaceous) with compositions closer to true HIMU (206Pb/204Pb(i) ≈ 20.5, 207Pb/204Pb(i) ≈ 15.7, 208Pb/204Pb(i) ≈ 40.0, εNd(i) ≈ 4.5 and εHf(i) ≈ 4.0). In contrast to the inboard HIMU-like magmas, the radiogenic 207Pb/204Pb and relatively unradiogenic Nd and Hf require an ancient enriched source component. This magmatism is interpreted to represent melting of a fossilised HIMU source that resided under the Hikurangi Plateau. These genetically distinct but isotopically similar intraplate reservoirs were separated by the down-going slab under Gondwana's former active margin. Ancient HIMU magmatism was locally replaced by the young HIMU-like type which became dominant across Zealandia during the Late Cretaceous. Our research suggests that the sources for alkaline intraplate magmas with compositions similar to ocean island basalts can be formed either with or without the involvement of a plume-derived component.

Nandrolone decanoate negatively reverses the beneficial effects of exercise on cardiac muscle via sarcolemmal, but not mitochondrial K(ATP) channel.

PubMed

Bayat, Gholamreza; Javan, Mohammad; Safari, Fatemeh; Khalili, Azadeh; Shokri, Saeed; Goudarzvand, Mahdi; Salimi, Mehdi; Hajizadeh, Sohrab

2016-03-01

ATP-sensitive potassium channels are supposed to have a substantial role in improvement of cardiac performance. This study was performed to evaluate whether nandrolone decanoate (ND) and (or) exercise training could affect the expression of cardiac K(ATP) channel subunits. Thirty-five male albino Wistar rats were randomly divided into 5 groups, including sedentary control (SC), sedentary vehicle (SV), sedentary ND (SND), exercise control (EC), and exercise and ND (E+ND). Exercise training was performed on a treadmill 5 times per week. ND was injected (10 mg/kg/week, i.m.) to the rats in the SND and E+ND groups. Following cardiac isolation, the expression of both sarcolemmal and mitochondrial subunits of K(ATP) channel was measured using Western blot method. The expression of sarcolemmal, but not mitochondrial, subunits of K(ATP) channel (Kir6.2 and SUR2) of EC group was significantly higher compared with SC group while ND administration (SND group) did not show any change in their expression. In the E+ND group, ND administration led to decrease of the over-expression of sarcolemmal Kir6.2 and SUR2 which was previously induced by exercise. There was no significant association between the mitochondrial expression of either Kir6.2 or SUR2 proteins and administration of ND or exercise. Supra-physiological dosage of ND negatively reverses the effects of exercise on the cardiac muscle expression of sarcolemmal, but not mitochondrial, K(ATP) channel subunits.

Nd-isotopes in selected mantle-derived rocks and minerals and their implications for mantle evolution

USGS Publications Warehouse

Basu, A.R.; Tatsumoto, M.

1980-01-01

The Sm-Nd systematics in a variety of mantle-derived samples including kimberlites, alnoite, carbonatite, pyroxene and amphibole inclusions in alkali basalts and xenolithic eclogites, granulites and a pyroxene megacryst in kimberlites are reported. The additional data on kimberlites strengthen our earlier conclusion that kimberlites are derived from a relatively undifferentiated chondritic mantle source. This conclusion is based on the observation that the e{open}Nd values of most of the kimberlites are near zero. In contrast with the kimberlites, their garnet lherzolite inclusions show both time-averaged Nd enrichment and depletion with respect to Sm. Separated clinopyroxenes in eclogite xenoliths from the Roberts Victor kimberlite pipe show both positive and negative e{open}Nd values suggesting different genetic history. A whole rock lower crustal scapolite granulite xenolith from the Matsoku kimberlite pipe shows a negative e{open}Nd value of -4.2, possibly representative of the base of the crust in Lesotho. It appears that all inclusions, mafic and ultramafic, in kimberlites are unrelated to their kimberlite host. The above data and additional Sm-Nd data on xenoliths in alkali basalts, alpine peridotite and alnoite-carbonatites are used to construct a model for the upper 200 km of the earth's mantle - both oceanic and continental. The essential feature of this model is the increasing degree of fertility of the mantle with depth. The kimberlite's source at depths below 200 km in the subcontinental mantle is the most primitive in this model, and this primitive layer is also extended to the suboceanic mantle. However, it is clear from the Nd-isotopic data in the xenoliths of the continental kimberlites that above 200 km the continental mantle is distinctly different from their suboceanic counterpart. ?? 1980 Springer-Verlag.

Petrogenesis of the postcollisional Middle Devonian monzonitic to granitic magmatism of the Sierra de San Luis, Argentina

NASA Astrophysics Data System (ADS)

López de Luchi, Mónica G.; Siegesmund, Siegfried; Wemmer, Klaus; Nolte, Nicole

2017-09-01

Middle Devonian granitoids intruded the Eastern Sierras Pampeanas basement ca. 600 km east of the inferred proto-Pacific margin of Gondwana along which a ca. 390 Ma collisional event developed. In the Sierra de San Luis, voluminous Middle Devonian (393-382 Ma) batholiths are composed of I- to A-type hybrid Monzonite and Granite suites. Shoshonite and subordinated high-K series, stocks, synplutonic dikes and enclaves make up the Monzonite Suite; rocks are metaluminous alkali-calcic magnesian porphyritic or equigranular monzonite, quartz monzonite, monzodiorite and scarce monzogabbro. High-K and subordinated shoshonite series metaluminous to mildly peraluminous magnesian alkali-calcic to calc-alkalic porphyritic or equigranular quartz monzonite, granodiorite, monzogranite and equigranular leucomonzogranites make up the Granite Suite plutons and batholiths. Only a small group of highly evolved granites are ferroan. SiO2 (46-62%), Cr, Ni, V, Sc, LILE, LREE, Th, Zr and variable, Sr/Y, (La/Yb)N and (Tb/Yb)N, smooth Eu/Eu*, moderate Na2O (ca 3.5), and troughs at Nb and Ta for Monzonite Suite rocks suggest an subduction-related enriched lithospheric mantle source. Sm-Nd data (TDM 0.98-1.08 Ga, εNd(380 Ma) 0.66-1.47) and 87Sr/86Sri (0.703520-0.704203) are compatible with an enriched mantle source. The metaluminous porphyritic quartz monzonite-monzogranite and the mildly peraluminous equigranular biotite monzogranites of the Granite Suite are characterized by relatively moderate Al2O3, CaO, and 87Sr/86Sri, high LILE, Cr, variable Sr/Y, (La/Yb)N and Eu/Eu* and low Rb/Sr (< 1.2) suggest a mafic source. The porphyritic monzogranite (TDM 1.20-1.28 Ga, εNd(380Ma) - 3.02 to - 3.3, 87Sr/86Sri 0.706578-0.707027) and the biotite monzogranites (TDM 1.31 Ga, εNd(380Ma) - 3.3, 87Sr/86Sri 0.707782) would share a common source. The equigranular alkali-calcic leucomonzogranites are characterized by Rb/Sr > 1.5, ASI 1.05-1.18, and Ga/Al 2.6-3.9, εNd(380 Ma) - 3.74 to - 3.95 and (87Sr/86Sr)i 0.710743-0.712955 which would point to metasedimentary or felsic igneous crustal sources. Nevertheless their TDM 1.36-1.38 Ga is considerably younger than the mean 1.8-1.6 Ga Eastern Sierras Pampeanas crustal residence age and less radiogenic. Middle Devonian magmatism would record an episode of crustal growth by enriched mantle derived magma input and variable degrees of partial melting of a lower crustal source at the waning stages of the Achalian orogeny.

Field Applicable Method to Reduce Dental Emergencies.

DTIC Science & Technology

1982-04-15

removed from a lower right 2nd molar and an orthodontic band was cemented and the tooth restored with the 70 percEnt SnF 2-polycarboxylate cement. 51 dAK...Martens & Mpqkin (1972) using only the buccal surfaces of 20 teeth (from 2nd premolars to 2nd pre - molars of both maxillary and mandibular arches). The...34 effect (Table 1, Fig. 3). Salivary and Urinary Fluoride Levels The pre -experimental baseline for salivary and urinary fluoride were 0.039 + 0.015 and

Mafic dikes at Kahel Tabelbala (Daoura, Ougarta Range, south-western Algeria): New insights into the petrology, geochemistry and mantle source characteristics

NASA Astrophysics Data System (ADS)

Mekkaoui, Abderrahmane; Remaci-Bénaouda, Nacéra; Graïne-Tazerout, Khadidja

2017-09-01

New petrological, geochemical and Sr-Nd isotopic data of the Late Triassic and Early Jurassic Kahel Tabelbala (KT) mafic dikes (south-western Algeria) offer a unique opportunity to examine the nature of their mantle sources and their geodynamic significance. An alkaline potassic Group 1 of basaltic dikes displaying relatively high MgO, TiO2, Cr and Ni, La/YbN ∼ 15, coupled with low 87Sr/86Sri ∼ 0.7037 and relatively high ɛNd(t) ∼ +3, indicates minor olivine and clinopyroxene fractionation and the existence of a depleted mantle OIB source. Their parental magma was generated from partial melting in the garnet-lherzolite stability field. A tholeiitic Group 2 of doleritic dikes displaying low MgO, Cr and Ni contents, La/YbN ∼ 5, positive Ba, Sr and Pb anomalies, the absence of a negative Nb anomaly coupled with moderate 87Sr/86Sri ∼ 0.7044 and low ɛNd(t) ∼ 0 (BSE-like), indicates a contamination of a mantle-derived magma that experienced crystal fractionation of plagioclase and clinopyroxene. This second group, similar to the low-Ti tholeiitic basalts of the Central Atlantic Magmatic Province (CAMP), was derived from partial melting in the peridotite source within the spinel stability field. Lower Mesozoic continental rifting could have been initiated by a heterogeneous mantle plume that supplied source components beneath Daoura, in the Ougarta Range.

Czochralski and modified Bridgman-Stockbarger growth of pure, Cd 2+ and Nd 3+ doped benzil single crystals

NASA Astrophysics Data System (ADS)

Aggarwal, M. D.; Wang, W. S.; Tambwe, M.

1993-03-01

Pure, Cd2+ and Nd3+-doped benzil C6H5COCOC6H5 have been grown from melt using the Czochralski and modified Bridgman-Stockbarger methods. Angle-tuned second harmonic generation of pure benzil from Nd:YAG laser radiation of λ = 1.06 μm with a conversion efficiency η = I2w/Iw = 0.4% has been demonstrated. We have used a Nd:YAG pulse laser to measure the radiation damage threshold as 15.9 MW/cm2 (c-axis) and 23.9 MW/cm2 (a-axis) under the conditions that laser pulse width is 10 ns. Under the same conditions, the conversion efficiency of Nd3+ and Cd2+-doped benzil, η= I2w/Iw = 1.1%, has been demonstrated. The radiation threshold is higher than for pure benzil crystals.

Two Distinct Sets of Magma Sources in Cretaceous Rocks From Magnet Cove, Prairie Creek, and Other Igneous Centers of the Arkansas Alkaline Province, USA

NASA Astrophysics Data System (ADS)

Duke, G. I.; Carlson, R. W.; Eby, G. N.

2008-12-01

Two distinct sets of magma sources from the Arkansas alkaline province (~106-89 Ma) are revealed by Sr-Nd-Pb isotopic compositions of olivine lamproites vs. other alkalic rock types, including carbonatite, ijolite, lamprophyres, tephrite, malignite, jacupirangite, phonolite, trachyte, and latite. Isotopic compositions of diamond-bearing olivine lamproites from Prairie Creek and Dare Mine Knob point to Proterozoic lithosphere as an important source, and previous Re-Os isotopic data indicate derivation from subcontinental mantle lithosphere. Both sources were probably involved in lamproite generation. Magnet Cove carbonatites and other alkalic magmas were likely derived from an asthenospheric source. Lamproite samples are isotopically quite different from other rock types in Sr-Nd-Pb isotopic space. Although three lamproite samples from Prairie Creek have a large range of SiO2 contents (40-60 wt %), initial values of ɛNd (-10 to -13), 206Pb/204Pb (16.61-16.81), 207Pb/204Pb (15.34-15.36), and 208Pb/204Pb (36.57-36.76) are low and similar. Only 87Sr/86Sr(i) displays a wide range in the Prairie Creek lamproites (0.70627-0.70829). A fourth lamproite from Dare Mine Knob has the most negative ɛNd(i) of -19. Lamproite isotope values show a significant crustal component and isotopically overlap subalkalic rhyolites from the Black Hills (SD), which assimilated Proterozoic crust. Six samples of carbonatite, ijolite, and jacupirangite from Magnet Cove and Potash Sulphur Springs exhibit the most depleted Sr-Nd isotopic signatures of all samples. For these rock types, 87Sr/86Sr(i) is 0.70352 - 0.70396, and ɛNd(i) is +3.8 - +4.3. Eight other rock types have a narrow range of ɛNd(i) (+1.9 - +3.7), but a wide range of 87Sr/86Sr(i) (0.70424 - 0.70629). These 14 samples comprise a fairly tight cluster of Pb isotopic values: 206Pb/204Pb (18.22-19.23), 207Pb/204Pb (15.54-15.62), and 208Pb/204Pb (38.38-38.94), suggesting very little crustal assimilation. They are most similar to EM-2 (sub-group of OIB). Published ages of crustal amphibolite xenoliths from the Prairie Creek lamproite are Proterozoic (~1.32- 1.47 Ga), in keeping with isotopic evidence for crustal assimilation, including Tdm = 1.3-1.7 Ga. Published ages of lamproite (~106 Ma) indicate that these magmas intruded first, whereas carbonatites and other alkalic magmas were later (~102 to ~89 Ma). Asthenospheric upwelling first melted lithospheric mantle and crust, producing lamproitic magmas; asthenospheric magmas followed as swelling of the lithosphere ensued.

Longitudinal spin Seebeck effect in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} prepared on gadolinium gallium garnet (001) by metal organic decomposition method

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

Asada, H., E-mail: asada@yamaguchi-u.ac.jp; Kuwahara, A.; Sakata, N.

2015-05-07

Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} thin films with the Ga composition x = 0, 0.5, and 1.0 are prepared on (001) oriented gadolinium gallium garnet substrates by a metal organic decomposition method. Only (001) peaks are observed in x-ray diffraction patterns for all the films, suggesting that the highly oriented Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} thin films were formed. Increasing Ga composition, the saturation magnetization decreases, and the perpendicular easy axis is enhanced due to the decrease of the shape anisotropy. Longitudinal spin Seebeck effects (LSSEs) in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} thin films with a Pt layer of 10 nm in thicknessmore » were investigated. Magnetic field dependence of the thermoelectric voltage caused by the LSSE in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} films indicates the hysteresis loop with the small coercivity reflecting the magnetization curve. The decrease of LSSE voltage in Nd{sub 2}BiFe{sub 5−x}Ga{sub x}O{sub 12} is clearly observed with the decrease of Fe composition.« less

A study of low threshold and high gain Nd3+ ions doped SiO2-B2O3-Na2CO3-NaF-CaF2 glasses for NIR laser applications

NASA Astrophysics Data System (ADS)

Megala, Rajesh; Gowthami, T.; John Sushma, N.; Kamala, S.; Deva Prasad Raju, B.

2018-05-01

Fluoroborosilicate glasses of composition 35SiO2-25B2O3-10Na2CO3-15NaF-15CaF2-xNd2O3 (where x = 0.1, 0.5. 1.0, 2.0 mol%) were prepared by melt quenching technique and various physical properties have been calculated. From the absorption spectra J-O Intensity parameters Ωλ (λ = 2, 4, 6) and radiative properties are evaluated by using J-O theory. The high values of Ω2 = 4.213 × 10-20 cm2, Ω4 = 5.345 × 10-20 cm2, Ω6 = 5.526 × 10-20 cm2 suggest that among the prepared glasses 0.5 mol% Nd glass is more asymmetric, more covalent and rigid in nature. The emission spectra were recorded with 808 nm laser as excitation source. The strong NIR emissions were observed at 876 nm, 1056 nm, 1328 nm corresponding to the transitions 4F3/2 → 4I9/2, 4F3/2 → 4I11/2, 4F3/2 → 4I13/2 respectively. Stimulated emission cross -section (σemi) and Gain bandwidth (σemi × Δλeff) were calculated. For 0.5 mol% Nd these values are found to be 3.30 × 10-20 cm2, 11 × 10-26 cm2. From the decay curve analysis the lifetime values for 4F3/2 level have been determined and these values are decreased with increase in Nd3+ ions concentration. These results may suggest that the prepared SBNCNd05 (Nd = 0.5 mol%) glass could be useful for 1056 nm laser applications.

1st- and 2nd-order motion and texture resolution in central and peripheral vision

NASA Technical Reports Server (NTRS)

Solomon, J. A.; Sperling, G.

1995-01-01

STIMULI. The 1st-order stimuli are moving sine gratings. The 2nd-order stimuli are fields of static visual texture, whose contrasts are modulated by moving sine gratings. Neither the spatial slant (orientation) nor the direction of motion of these 2nd-order (microbalanced) stimuli can be detected by a Fourier analysis; they are invisible to Reichardt and motion-energy detectors. METHOD. For these dynamic stimuli, when presented both centrally and in an annular window extending from 8 to 10 deg in eccentricity, we measured the highest spatial frequency for which discrimination between +/- 45 deg texture slants and discrimination between opposite directions of motion were each possible. RESULTS. For sufficiently low spatial frequencies, slant and direction can be discriminated in both central and peripheral vision, for both 1st- and for 2nd-order stimuli. For both 1st- and 2nd-order stimuli, at both retinal locations, slant discrimination is possible at higher spatial frequencies than direction discrimination. For both 1st- and 2nd-order stimuli, motion resolution decreases 2-3 times more rapidly with eccentricity than does texture resolution. CONCLUSIONS. (1) 1st- and 2nd-order motion scale similarly with eccentricity. (2) 1st- and 2nd-order texture scale similarly with eccentricity. (3) The central/peripheral resolution fall-off is 2-3 times greater for motion than for texture.

Synthesis and Characterization of Nd(3+)-Doped CaF2 Nanoparticles.

PubMed

Yuan, Dan; Li, Weiwei; Mei, Bingchu; Song, Jinghong

2015-12-01

The Ca(1-x)F(2+x):Nd(x) nanoparticles were synthesized by chemical direct precipitation method. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Image analyzer, absorption spectrum and transmittance were taken to characterization the phases, morphologies, sizes, size distribution and optical properties of the samples. The results indicate that the Ca(1-x)F(2+x):Nd(x) samples can be rationally modified in size and morphology by altering the Nd3+ ions doping concentration. With increasing concentration of Nd3+ ions, the particle size decreased from 24 to 14 nm, the intensity of the diffraction peaks decreased, the Ca(1-x)F(2+x):Nd(x) particles aggregated ion of the formed clusters which should have an effect on both speed and orientation of the particles growth. The transmittance of ceramics with a thickness of 2 mm showed that the transmittance can reach 90% when the doping concentration was 5%, which should be profitable for LD pumping.

Spectrophotometric methods for the determination of urea in real samples using silver nanoparticles by standard addition and 2nd order derivative methods

NASA Astrophysics Data System (ADS)

Ali, Nauman; Ismail, Muhammad; Khan, Adnan; Khan, Hamayun; Haider, Sajjad; Kamal, Tahseen

2018-01-01

In this work, we have developed simple, sensitive and inexpensive methods for the spectrophotometric determination of urea in urine samples using silver nanoparticles (AgNPs). The standard addition and 2nd order derivative methods were adopted for this purpose. AgNPs were prepared by chemical reduction of AgNO3 with hydrazine using 1,3-di-(1H-imidazol-1-yl)-2-propanol (DIPO) as a stabilizing agent in aqueous medium. The proposed methods were based on the complexation of AgNPs with urea. Using this concept, urea in the urine samples was successfully determined spectrophotometric methods. The results showed high percent recovery with ± RSD. The recoveries of urea in the three urine samples by spectrophotometric standard addition were 99.2% ± 5.37, 96.3% ± 4.49, 104.88% ± 4.99 and that of spectrophotometric 2nd order derivative method were 115.3% ± 5.2, 103.4% ± 2.6, 105.93% ± 0.76. The results show that these methods can open doors for a potential role of AgNPs in the clinical determination of urea in urine, blood, biological, non-biological fluids.

Mantle transition zone-derived EM1 component beneath NE China: Geochemical evidence from Cenozoic potassic basalts

NASA Astrophysics Data System (ADS)

Wang, Xiao-Jun; Chen, Li-Hui; Hofmann, Albrecht W.; Mao, Fu-Gen; Liu, Jian-Qiang; Zhong, Yuan; Xie, Lie-Wen; Yang, Yue-Heng

2017-05-01

The isotopic characteristics of the sub-oceanic mantle are well established, but in continental regions these properties are usually obscured, and therefore controversial, because of the potential effects of crustal contamination together with lithospheric mantle metasomatism and melting. The so-called EM1 (Enriched Mantle-1) signature, characterized by low 206Pb/204Pb and 143Nd/144Nd ratios, is particularly problematic in this respect because EM1-type OIB sources are commonly attributed to recycled crust and/or lithospheric mantle. In this paper we show that a suite of Cenozoic potassic basalts from NE China displays many previously unrecognized correlations between chemical and isotopic parameters, which tightly constrain the isotopic characteristics of an extreme EM1-type mantle source located in the asthenosphere. Its radiogenic isotopes are similar to, but even more extreme than, those of the oceanic endmember composition represented by the Pitcairn hotspot, namely 206Pb/204Pb ≤ 16.5, 143Nd/144Nd ≤ 0.5123 (or εNd ≤ - 6.4), 176Hf/177Hf ≤ 0.2825 (or εHf ≤ - 10.1). These characteristics require a source of recycled crustal material of Precambrian age (∼2.2 Ga). An important new constraint is the Mg isotopic composition of δ26 Mg (≤ - 0.6 ‰), which is lower than normal mantle (δ26 Mg = - 0.25 ± 0.07 ‰) and lower crustal values (δ26 Mg = - 0.29 ± 0.15 ‰), but consistent with sedimentary carbonate (δ26 Mg = - 5.57 ‰ to - 0.38 ‰). The endmember EM1 source produced high-SiO2 melts with low MgO, CaO/Al2O3 and δ26 Mg values, exceptionally high K/U ≅ 50,000, Ba/Th ≅ 400, low U/Pb ≅ 0.06, and positive Zr and Hf anomalies. The chemical and isotopic parameters of this potassic basalt suite form binary mixing arrays, one end point of which is the inferred asthenospheric EM1 reservoir, whereas the other is a more ordinary, depleted mantle component, which is also sampled by local lithospheric mantle xenoliths. These binary arrays include well-developed correlations between Sr, Nd, Hf, Pb and Mg isotopes, negative correlations of 206Pb/204Pb with K2 O, K/U, Hf/Hf*, positive correlations of δ26 Mg with MgO, and 143Nd/144Nd with Fe2OT3 and U/Pb. We propose that the EM1 reservoir contains recycled ancient carbonate-bearing sediments, subducted into the mantle transition zone, where K, Rb, Ba and Pb are sequestered by K-hollandite as suggested by Murphy et al. (2002) for the Gaussberg lamproites. Loss of small amounts of carbonate melt extracted Th, U and some of the LREE, while retaining K, Rb, Ba, Pb, Zr and Hf in the residue, thereby generating the observed trace element anomalies. In Cenozoic time, this deep EM1 reservoir ascended into the shallow asthenosphere and underwent low-degree partial melting, at pressures below the stability field of K-hollandite, thereby releasing K, Rb and Ba into the melt. The partial melts ascended through subcontinental lithosphere and were progressively modified by interaction with the lithospheric mantle, thus accounting for the linear chemical and isotopic trends noted above. This interaction imposed a progressively more depleted character on the erupted melt, both in terms of isotopic composition and trace element enrichment.

Bond-selective photodissociation of partially deuterated ammonia molecules: Photodissociations of vibrationally excited NHD2 in the 5νNH state and NH2D in the 5νND state

NASA Astrophysics Data System (ADS)

Akagi, Hiroshi; Yokoyama, Keiichi; Yokoyama, Atsushi

2004-03-01

Ultraviolet photodissociation of NHD2 excited to the fourth overtone state of the NH stretching mode (5νNH) and NH2D excited to that of the ND stretching mode (5νND) has been investigated by using a crossed laser and molecular beams method. Branching ratio between the NH and ND bond dissociations has been determined by utilizing a (2+1) resonance enhanced multiphoton ionization scheme of H and D atoms. For the photolysis of NHD2 in the 5νNH state, the NH dissociation cross section is 5.1±1.4 times as large as the ND dissociation cross section per bond. On the other hand, for the photolysis of NH2D in the 5νND state, the ratio of the NH dissociation cross section per bond to the ND dissociation cross section decreases to 0.68±0.16. In comparison with the branching ratios for the photolysis of vibrationally unexcited NH2D and NHD2 [Koda and Back, Can. J. Chem. 55, 1380 (1977)], the present results indicate that the excitation of the NH stretching mode enhances the NH dissociation with ca. two times larger NH/ND branching ratio, whereas the excitation of the ND stretching mode results in the preferential ND dissociation with ca. 3-4 times larger ND/NH branching ratio than that for the vibrational ground states. The mechanism of the bond-selective enhancement has been discussed in terms of the energetics and dynamics of wave packet.

DAMP-Mediated Innate Immune Failure and Pneumonia after Trauma

DTIC Science & Technology

2017-10-01

Correlation Between Chemotaxis and Ca2+ release AUC ND6 ND3 ND4 ND5 COX1 6 similarity of amino acid sequences based upon their component residues. We used... correlation to chemotaxis studies. These findings give us confidence that our mechanistic studies in mice can be able be used translationally to...evaluated time-dependent changes in peripheral blood in trauma patients to identify changes correlated with infection. Methods: Total leukocytes were

Treatment of reverse osmosis (RO) concentrate by the combined Fe/Cu/air and Fenton process (1stFe/Cu/air-Fenton-2ndFe/Cu/air).

PubMed

Ren, Yi; Yuan, Yue; Lai, Bo; Zhou, Yuexi; Wang, Juling

2016-01-25

To decompose or transform the toxic and refractory reverse osmosis (RO) concentrate and improve the biodegradability, 1stFe/Cu/air-Fenton-2ndFe/Cu/air were developed to treat RO concentrate obtained from an amino acid production plant in northern China. First, their operating conditions were optimized thoroughly. Furthermore, 5 control experiments were setup to confirm the superiority of 1stFe/Cu/air-Fenton-2ndFe/Cu/air and synergistic reaction between Fe/Cu/air and Fenton. The results suggest that the developed method could obtain high COD removal (65.1%) and BOD5/COD ratio (0.26) due to the synergistic reaction between Fe/Cu/air and Fenton. Under the optimal conditions, the influent and effluent of 1stFe/Cu/air-Fenton-2ndFe/Cu/air and 5 control experiments were analyzed by using UV, FTIR, EEM and LC, which confirm the superiority of 1stFe/Cu/air-Fenton-2ndFe/Cu/air. Therefore, the developed method in this study is a promising process for treatment of RO concentrate. Copyright © 2015 Elsevier B.V. All rights reserved.

Submarine groundwater discharge of rare earth elements: Evidence of an important trace element flux to coastal waters

NASA Astrophysics Data System (ADS)

Johannesson, K. H.; Chevis, D.; Burdige, D. J.; Cable, J. E.; Martin, J. B.; Roy, M.

2008-12-01

Johannesson and Burdige [2007, EPSL 253, 129] suggested that submarine groundwater discharge (SGD) represents a substantial, unrecognized source of Nd to the oceans. Based on a globally averaged terrestrial SGD flux equal to 6 percent of the global river discharge and mean groundwater Nd concentrations obtained from the literature, we estimated a global SGD Nd flux that was within a factor of 2 of the previously proposed missing global Nd flux. To test our hypothesis that SGD is an important source of Nd to the oceans, rare earth element (REE) concentrations were measured in SGD samples collected beneath a coastal lagoon on the Florida Atlantic coast (Indian River Lagoon). Shale (PAAS)-normalized REE patterns for all SGD samples exhibit substantial enrichments in the heavy REEs (HREE) compared to the light REEs (LREE) as shown by their PAAS-normalized Yb/Nd ratios, which range from 5 to 73 (mean = 16). SGD from piezometers located 10 m and 22.5 m from shore exhibit PAAS-normalized REE plots that are most similar to the patterns of the overlying lagoon (surface) water. For example, mean PAAS-normalized Yb/Nd ratios for groundwaters sampled from the 10 m and 22.5 m piezometers are 6.7 and 8.3, which compare well with the PAAS- normalized Yb/Nd ratio of water column samples (8.7). In contrast, the mean PAAS-normalized Yb/Nd ratio of terrestrial-derived groundwater from the piezometer at the shoreline is 41. Neodymium concentrations of the SGD samples range from 230 to 2400 pmol/kg (mean = 507 pmol/kg), and thus are substantially higher than reported for open ocean seawater (typical Nd = 20 pmol/kg). Based on SGD fluxes previously determined with seepage meters, porewater Cl concentrations, and Rn-222 deficiencies of porewaters [Martin et al., 2007, Water Resour. Res. 43, W0544, doi: 10.1029/2006WR005266], we estimate daily inputs of Nd to the Indian River Lagoon of 50 to 2100 umoles for the terrestrial-derived component of SGD, and 171 mmoles for the marine component of SGD (81 to 3400 times greater). Residence times of Nd in the portion of the lagoon studied are estimated to range from 6 to more than 250 years based on the terrestrial-derived SGD flux of Nd, compared to 26 days using the marine-derived SGD flux of Nd. The substantially shorter residence time determined using the marine-derived SGD component compares well with the estimated flushing time for this portion of the estuary (~3 weeks). The similarity between SGD and lagoon water Nd concentrations and PAAS-normalized REE patterns, in conjunction with the larger, marine-derived SGD flux of Nd, strongly suggests that recirculation of lagoon water and subsequent SGD exerts the principal control on Nd concentrations in the lagoon. The elevated Nd concentration for deep groundwater (186 cmbsf) located 22.5 m from shore also agrees well with another study that reported recirculated, marine SGD as a source of REEs to coastal waters [Duncan and Shaw, 2003, Aquatic Geochem. 9, 233]. Thus, our observations demonstrate the importance of recirculated, marine SGD to these lagoon surface waters, and further support our hypothesis that SGD contributes substantial fluxes of Nd to the coastal oceans.

The Mesoarchean Tiejiashan-Gongchangling potassic granite in the Anshan-Benxi area, North China Craton: Origin by recycling of Paleo- to Eoarchean crust from U-Pb-Nd-Hf-O isotopic studies

NASA Astrophysics Data System (ADS)

Dong, Chunyan; Wan, Yusheng; Xie, Hangqiang; Nutman, Allen P.; Xie, Shiwen; Liu, Shoujie; Ma, Mingzhu; Liu, Dunyi

2017-10-01

Mesoarchean and older potassic granites are important indicators of recycling of ancient continental crust early in Earth's history. This study of integrated whole rock and zircon geochemistry and geochronology reports the age and identification of the source materials of the > 200 km2 Mesoarchean Tiejiashan-Gongchangling granite in the Anshan-Benxi area, North China Craton, the largest pre-Neoarchean granite domain in the craton. SHRIMP U-Pb zircon dating on 15 samples indicates the magmatic crystallization of the granites between 2.95 and 3.0 Ga and reveals a superimposed tectonothermal event at 2.91 Ga. The granites are characterized by high SiO2 and K2O, low CaO, FeOt, MgO and TiO2 with peraluminuous features. They show large variations in (La/Yb)n and strong negative Eu and Ba anomalies and Nb, P and Ti depletions. Whole rock Nd and magmatic zircon Hf isotopic compositions show large variations, but with most having εNd(t) and εHf(t) values < 0, with tDM(Nd) and tDM(Hf) values varying from 3.3 to 3.9 Ga and 3.3 to 4.0 Ga, respectively. Magmatic zircons without very strong lead loss (discordance ≤ 20%) have δ18O values of + 3.14 to + 8.39. 3.3-3.7 Ga xenocrystic zircons occur in some samples. The granite formed as a result of recycling of Paleo- to Eoarchean continental material in an intracontinental environment, with little if any contribution from Mesoarchean mantle sources. The sources could be predominantly unaltered ancient gneisses, together with yet to be identified Paleo- to Eoarchean materials affected by early low temperature alteration (weathered rocks or clastic sediment).

Coercivity enhancement mechanism in Dy-substituted Nd-Fe-B nanoparticles synthesized by sol-gel base method followed by a reduction-diffusion process

NASA Astrophysics Data System (ADS)

Rahimi, Hamed; Ghasemi, Ali; Mozaffarinia, Reza; Tavoosi, Majid

2017-05-01

In current work, Nd15-xDyxFe77.5B7.5 (at%) nanoparticles with different Dy-content (x=0.0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0) were synthesized by sol-gel method followed by a reduction-diffusion process. The effects of Dy on the magnetic properties and the relations between the microstructure and the coercivity of Dy-substituted Nd-Fe-B nanoparticles have been studied. The coercivity of Nd-Fe-B nanoparticles with the addition of Dy first increase, reaches a maximum, and then starts to decrease. The coercivity of Dy-substituted Nd-Fe-B nanoparticle synthesized by sol-gel method increased from 938.9 to 1663.9 kA/m while the remanence decreased slightly from 1.16 to 1.06 T. The results show that with an increase in Dy content the variation of maximum energy product ((BH)max), lowest-order uniaxial magnetocrystalline anisotropy constant (Ku1), and Curie temperature (Tc) had a trend as same as the coercivity. The Henkel plot showed that the existence of exchange coupling interaction between grains, and the exchange coupling interactions increased with increasing x from 0.0 to 2.0 and then decrease with further increasing x≥2.5. The optimum magnetic properties of Nd-Fe-B nanoparticles with (BH)max =40.38 MGOe, Hc=1663.9 kA/m, Br=1.08 T were obtained by substituted 2.0 at% Dy. The effects of increasing temperature on magnetic properties of Dy-substituted Nd-Fe-B nanoparticle magnets with 2.0 at% Dy was investigated. The reduced spin-reorientation temperature was obtained for Dy-substituted Nd-Fe-B nanoparticles with 2.0 at% Dy. Below 100 K a spin-reorientation transition was takes place. The temperature coefficient of coercivity (β) was -0.36, -0.46, -0.41, -0.34, -0.29, -0.24, -0.25%/°C at different temperature 50, 100, 150, 200, 250, 300, 350 °C, respectively. Mössbauer spectroscopy was applied to study the composition and properties of Dy-substituted Nd-Fe-B magnet. Microstructure analysis showed a homogeneous distribution of Dy in produced samples. The possible reason for observed magnetic behavior is improving the intrinsic material parameter and optimizing the microstructure by a uniform enhancement of magnetocrystalline anisotropy by formation the nanocrystalline compound (Nd,Dy)2Fe14B.

Novel Antigen Identification Method for Discovery of Protective Malaria Antigens by Rapid Testing of DNA Vaccines Encoding Exons from the Parasite Genome

DTIC Science & Technology

2004-03-01

EAA21673 1,443 — — Xeroderma pigmentosum G N&I region, helix-hairpin-helix class P.f., P.k., P.b., P.v. PY02286 EAA21722 696 — — Hypothetical protein...ND PY01828 Gene gun 0.1 2,560 640 Pos IM 0.1 Neg Neg ND CSP Gene gun 0.1 2,560 Neg Neg IM 2.7* 2,560 Neg ND a Parasite burden in liver is in...negative; Pos , positive; ND, not done. c Sera tested at a single dilution (1:80). VOL. 72, 2004 DISCOVERY OF PROTECTIVE MALARIA PARASITE ANTIGENS 1599

Low temperature texture development in Nd2Fe14B/α-Fe nanocomposite magnets via equal channel angular pressing

NASA Astrophysics Data System (ADS)

Besley, L.; Garitaonandia, J. S.; Molotnikov, A.; Kishimoto, H.; Kato, A.; Davies, C.; Suzuki, K.

2018-05-01

While suitable texture has been developed in Nd2Fe14B/α-Fe nanocomposites via thermomechanical processing methods such as die upsetting by incorporating low melting point eutectic Nd-Cu additives, significant grain coarsening occurs during this process due to the high temperature and long timescales involved, resulting in a loss of exchange coupling. Equal channel angular pressing (ECAP) is a severe plastic deformation technique which has been successfully used to produce a suitable texture in single-phase Nd2Fe14B at temperatures on the order of 500°C while preserving grain sizes on the order of 20-30nm. We investigate the development of texture in a commercial Nd2Fe14B/α-Fe nanocomposite alloy with added Nd90Cu10 produced via ECAP and then characterise it using texture x-ray diffraction and magnetic measurements. It is found that initial texture can be developed in this nanocomposite system at T = 520°C via ECAP. The average grain size of Nd2Fe14B as measured via X-ray diffraction after ECAP remains below 50nm with a developed texture. The effect of varying the amount of Nd90Cu10 additive is also investigated. It is found that with decreasing Nd90Cu10, the degree of texture is reduced while the volume fraction of α-Fe increases. This work demonstrates the development of texture in nanocomposite Nd2Fe14B/α-Fe with Nd-Cu additives whilst maintaining a grain size of approximately 50nm.

Demagnetization of Nd 2Fe 14B, Pr 2Fe 14B, and Sm 2Co 17 Permanent Magnets in Spallation Irradiation Fields

DOE PAGES

Simos, Nikolaos; Ozaki, S.; Mokhov, N.; ...

2018-02-27

Prompted by the need for radiation-resistant permanent magnets for insertion devices (IDs) of high-brilliance next-generation synchrotrons such as the National Synchrotron Light Source II, the demagnetization of Nd 2Fe 14B and Pr 2Fe 14B was studied after exposure to a mixed irradiating field. Degradation and damage of the permanent magnetic material by components of electromagnetic showers induced in magnets by intense high-energy electron beams will alter the magnetic field structure of the IDs. Plate-like Nd 2Fe 14B magnets were irradiated to 1.8 Grad dose and were evaluated against Pr 2Fe 14B magnets irradiated to a lower dose of 20 Mrad.more » In addition, annular Sm 2Co 17 and Nd 2Fe 14B magnets integrated within a ferrofluidic feedthrough (FFFT) rotary seal were also irradiated to dose levels of 2 Grad for Sm 2Co 17 and 20 Mrad for Nd 2Fe 14B. Post-irradiation measurements of the magnetic intensity revealed that severe demagnetization exceeding 85% occurs in Nd 2Fe 14B magnets after only 50 Mrad dose and over 87% for Pr 2Fe 14B after 10 Mrad dose. The annular-shaped Sm 2Co 17 magnets of the FFFTs were almost insensitive to irradiation up to a dose of 2 Grad. Annular-shaped Nd 2Fe 14B magnets also showed resistance to demagnetization, a direct consequence of the annular shape which is characterized by the removal of the stronger demagnetizing field present at the center of a disk-like magnet. As a result, the sensitivity of boron-based permanent magnets to neutron energy (thermal versus fast) was also assessed via specifically designed experiments and discussed.« less

Demagnetization of Nd 2Fe 14B, Pr 2Fe 14B, and Sm 2Co 17 Permanent Magnets in Spallation Irradiation Fields

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

Simos, Nikolaos; Ozaki, S.; Mokhov, N.

Prompted by the need for radiation-resistant permanent magnets for insertion devices (IDs) of high-brilliance next-generation synchrotrons such as the National Synchrotron Light Source II, the demagnetization of Nd 2Fe 14B and Pr 2Fe 14B was studied after exposure to a mixed irradiating field. Degradation and damage of the permanent magnetic material by components of electromagnetic showers induced in magnets by intense high-energy electron beams will alter the magnetic field structure of the IDs. Plate-like Nd 2Fe 14B magnets were irradiated to 1.8 Grad dose and were evaluated against Pr 2Fe 14B magnets irradiated to a lower dose of 20 Mrad.more » In addition, annular Sm 2Co 17 and Nd 2Fe 14B magnets integrated within a ferrofluidic feedthrough (FFFT) rotary seal were also irradiated to dose levels of 2 Grad for Sm 2Co 17 and 20 Mrad for Nd 2Fe 14B. Post-irradiation measurements of the magnetic intensity revealed that severe demagnetization exceeding 85% occurs in Nd 2Fe 14B magnets after only 50 Mrad dose and over 87% for Pr 2Fe 14B after 10 Mrad dose. The annular-shaped Sm 2Co 17 magnets of the FFFTs were almost insensitive to irradiation up to a dose of 2 Grad. Annular-shaped Nd 2Fe 14B magnets also showed resistance to demagnetization, a direct consequence of the annular shape which is characterized by the removal of the stronger demagnetizing field present at the center of a disk-like magnet. As a result, the sensitivity of boron-based permanent magnets to neutron energy (thermal versus fast) was also assessed via specifically designed experiments and discussed.« less

The formation and optical properties of planar waveguide in laser crystal Nd:YGG by carbon ion implantation

NASA Astrophysics Data System (ADS)

Zhao, Jin-Hua; Qin, Xi-Feng; Wang, Feng-Xiang; Jiao, Yang; Guan, Jing; Fu, Gang

2017-10-01

As one kind of prominent laser crystal, Nd:Y3Ga5O12 (Nd:YGG) crystal has outstanding performance on laser excitation at multi-wavelength which have shown promising applications in optical communication field. In addition, Nd:YGG crystal has potential applications in medical field due to its ability of emit the laser at 1110 nm. Optical waveguide structure with high quality could improve the efficiency of laser emission. In this work, we fabricated the optical planar waveguide on Nd:YGG crystal by medium mass ion implantation which was convinced an effective method to realize a waveguide structure with superior optical properties. The sample is implanted by C ions at energy of 5.0 MeV with the fluence of 1 × 1015 ions/cm2. We researched the optical propagation properties in the Nd:YGG waveguide by end-face coupling and prism coupling method. The Nd ions fluorescent properties are obtained by a confocal micro-luminescence measurement. The fluorescent properties of Nd ions obtained good reservation after C ion implantation. Our work has reference value for the application of Nd:YGG crystal in the field of optical communication.

Early onset of magma ocean crystallization revealed by coupled 146,147Sm-142,143Nd systematics of Nulliak ultramafics (3.78 Ga, Labrador)

NASA Astrophysics Data System (ADS)

Morino, P.; Caro, G.; Reisberg, L. C.

2015-12-01

Early onset of magma ocean crystallization revealed by coupled 146,147Sm-142,143Nd systematics of Nulliak ultramafics (3.78 Ga, Labrador) Precillia Morino1, Guillaume Caro1, Laurie Reisberg 1 1CRPG-CNRS, Université de Lorraine, Nancy, France Coupled 146,147Sm-142,143Nd systematics provides constraints on the timing of magma ocean crystallization on Mars, the Moon and Vesta. Estimates for the Earth's mantle, however, are less accurate owing to the sparsity of Eoarchean mantle-derived rocks with undisturbed 147Sm-143Nd systematics. This study attempts to establish a coherent 142,143Nd dataset for the Eoarchean mantle using well-preserved ultramafic rocks from the Nulliak assemblage (Labrador). Samples include meta-dunites, -pyroxenites and -peridotites exhibiting only minor serpentinization and limited element mobility. The presence of "Barberton type" komatiitic compositions (low Al/Ti, HREE depletion) is suggestive of a deep mantle source. 146,147Sm-142,143Nd and 187Re-187Os analyses yield a crystallization age of 3.78±0.09 Ga with ɛ143Ndi=1.5±0.2 and ɛ142Nd=8.6±2 ppm. This 142,143Nd signature yields a model age of mantle differentiation of 4.43±0.05 Ga (assuming a BSE with chondritic Sm/Nd and ɛ142Nd=0). Superchondritic Sm/Nd compositions for the BSE would translate into older model ages. Irrespective of the choice of primitive mantle composition, Nulliak ultramafics provide differentiation ages 100 Ma older than those estimated from Akilia tonalites but remarkably similar to that estimated from the 2.7 Ga Theo's flow (Abitibi). If Nulliak ultramafics originated from deep melting of a hot plume, their model age could reflect the early onset of magma ocean crystallization in the lowermost mantle.

An efficient continuous-wave 591 nm light source based on sum-frequency mixing of a diode pumped Nd:GdVO4-Nd:CNGG laser

NASA Astrophysics Data System (ADS)

Zhao, Y. D.; Liu, J. H.

2013-08-01

We report a laser architecture to obtain continuous-wave (CW) yellow-orange light sources at the 591 nm wavelength. An 808 nm diode pumped a Nd:GdVO4 crystal emitting at 1063 nm. A part of the pump power was then absorbed by the Nd:CNGG crystal. The remaining pump power was used to pump a Nd:CNGG crystal emitting at 1329 nm. Intracavity sum-frequency mixing at 1063 and 1329 nm was then realized in a LiB3O5 (LBO) crystal to reach the yellow-orange radiation. We obtained a CW output power of 494 mW at 591 nm with a pump laser diode emitting 17.8 W at 808 nm.

Lu-Hf and Sm-Nd Isotopic Studies of Shergottites and Nakhlites: Implications for Martian Mantle Sources

NASA Technical Reports Server (NTRS)

Debaille, V.; Yin, Q.-Z.; Brandon, A. D.; Jacobsen, B.; Treiman, A. H.

2007-01-01

We present a new Lu-Hf and Sm-Nd isotope systematics study of four enriched shergottites (Zagami, Shergotty, NWA856 and Los Angeles), and three nakhlites (Nakhla, MIL03346 and Yamato 000593) in order to further understand processes occurring during the early differentiation of Mars and the crystallization of its magma ocean. Two fractions of the terrestrial petrological analogue of nakhlites, the Archaean Theo's flow (Ontario, Canada) were also measured. The coupling of Nd and Hf isotopes provide direct insights on the mineralogy of the melt sources. In contrast to Sm/Nd, Lu/Hf ratios can be very large in minerals such as garnet. Selective partial melting of garnet bearing mantle sources can therefore lead to characteristic Lu/Hf signatures that can be recognized with Hf-176/Hf-177Hf ratios.

(U) Second-Order Sensitivity Analysis of Uncollided Particle Contributions to Radiation Detector Responses Using Ray-Tracing

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

Favorite, Jeffrey A.

The Second-Level Adjoint Sensitivity System (2nd-LASS) that yields the second-order sensitivities of a response of uncollided particles with respect to isotope densities, cross sections, and source emission rates is derived in Refs. 1 and 2. In Ref. 2, we solved problems for the uncollided leakage from a homogeneous sphere and a multiregion cylinder using the PARTISN multigroup discrete-ordinates code. In this memo, we derive solutions of the 2nd-LASS for the particular case when the response is a flux or partial current density computed at a single point on the boundary, and the inner products are computed using ray-tracing. Both themore » PARTISN approach and the ray-tracing approach are implemented in a computer code, SENSPG. The next section of this report presents the equations of the 1st- and 2nd-LASS for uncollided particles and the first- and second-order sensitivities that use the solutions of the 1st- and 2nd-LASS. Section III presents solutions of the 1st- and 2nd-LASS equations for the case of ray-tracing from a detector point. Section IV presents specific solutions of the 2nd-LASS and derives the ray-trace form of the inner products needed for second-order sensitivities. Numerical results for the total leakage from a homogeneous sphere are presented in Sec. V and for the leakage from one side of a two-region slab in Sec. VI. Section VII is a summary and conclusions.« less

Geochemical and NdSr isotopic composition of deep-sea turbidites: Crustal evolution and plate tectonic associations

NASA Astrophysics Data System (ADS)

McLennan, S. M.; Taylor, S. R.; McCulloch, M. T.; Maynard, J. B.

1990-07-01

Petrographic, geochemical, and isotopic data for turbidites from a variety of tectonic settings exhibit considerable variability that is related to tectonic association. Passive margin turbidites (Trailing Edge, Continental Collision) display high framework quartz (Q) content in sands, evolved major element compositions (high Si/Al, K/Na), incompatible element enrichments (high Th/Sc, La/Sc, La/Yb), negative Eu-anomalies and variable Th/U ratios. They have low 143Nd /144Nd and high 87Sr /86Sr ( ɛNd = -26 to -10; 87Sr /86Sr = 0.709 to 0.734 ), indicating a dominance of old upper crustal sources. Active margin settings (Fore Arc, Continental Arc, Back Arc, Strike Slip) commonly exhibit quite different compositions. Th/Sc varies from <0.01 to 1.8, and ɛNd varies from -13.8 to +8.3. Eu-anomalies range from no anomaly ( Eu/Eu ∗ = 1.0 ) to Eu-depletions typical of post-Archean shales ( Eu/Eu ∗ = 0.65 ). Active margin data are explained by mixtures of young arc-derived material, with variable composition and old upper crustal sources. Major element data indicate that passive margin turbidites have experienced more severe weathering histories than those from active settings. Most trace elements are enriched in muds relative to associated sands because of dilution effects from quartz and calcite and concentration of trace elements in clays. Exceptions include Zr, Hf (heavy mineral influence) and Tl (enriched in feldspar) which display enrichments in sands. Active margin sands commonly exhibit higher Eu/Eu ∗ than associated muds, resulting from concentration of plagioclase during sorting. Some associated sands and muds, especially from active settings, have systematic differences in Th/Sc ratios and Nd-isotopic composition, indicating that various provenance components may separate into different grain-size fractions during sedimentary sorting processes. Trace element abundances of modern turbidites, from both active and passive settings, differ from Archean turbidites in several important ways. Modern turbidites have less uniformity, for example, in Th/Sc ratios. On average, modern turbidites have greater depletions in Eu (lower Eu/Eu ∗) than do Archean turbidites, suggesting that the processes of intracrustal differentiation (involving plagioclase fractionation) are of greater importance for crustal evolution at modern continental margins than they were during the Archean. Modern turbidites do not display HREE depletion, a feature commonly seen in Archean data. HREE depletion ( Gd N/Yb N > 2.0 ) in Archean sediments results from incorporation of felsic igneous rocks that were in equilibrium (or their sources were in equilibrium) with garnet sometime in their history. Absence of HREE depletion at modern continental margins suggests that processes of crust formation (or mantle source compositions) may have differed. Differences in trace element abundances for Archean and modern turbidites add support to suggestions that upper continental crust compositions and major processes responsible for continental crust differentiation differed during the Archean. Neodymium model ages, thought to approximate average provenance age, are highly variable ( TDMND = 0-2.6 Ga) in modern turbidites, in contrast with studies that indicate Nd-model ages of lithified Phanerozoic sediment are fairly constant at about 1.5-2.0 Ga. This variability indicates that continental margin sediments incorporate new mantle-derived components, as well as continental crust of widely varying age, during recycling. The apparent dearth of ancient sediments with Nd-model age similar to stratigraphic age supports the suggestion that preservation potential of sediments is related to tectonic setting. Many samples from active settings have isotopic compositions similar to or only slightly evolved from mantle-derived igneous rocks. Subduction of active margin turbidites should be considered in models of crust-mantle recycling. For short-term recycling, such as that postulated for island arc petrogenesis, arc-derived turbidites cannot be easily recognized as a source component because of the lack of time available for isotopic evolution. If turbidites were incorporated into the sources of ocean island volcanics, the isotopic signatures would be considerably more evolved since most models call for long mantle storage times (1.0-2.0 Ga), prior to incorporation. Four provenance components are recognized on the basis of geochemistry and Nd-isotopic composition: (1) Old Upper Continental Crust (old igneous/metamorphic terranes, recycled sediment); (2) Young Undifferentiated Arc (young volcanic/plutonic source that has not experienced plagioclase fractionation); (3) Young Differentiated Arc (young volcanic/plutonic source that has experienced plagioclase fractionation); (4) MORB (minor). Relative proportions of these components are influenced by the plate tectonic association of the provenance and are typically (but not necessarily) reflected in the depositional basin. Provenance of quartzose (mainly passive settings) and non-quartzose (mainly active settings) turbidites can be characterized by bulk composition (e.g., Th/Sc) and Nd-isotopic composition (reflecting age).

Magnetic properties and magnetization reversal mechanism of Nd-Fe-B nanoparticles synthesized by a sol-gel method

NASA Astrophysics Data System (ADS)

Rahimi, Hamed; Ghasemi, Ali; Mozaffarinia, Reza; Tavoosi, Majid

2017-12-01

Nd-Fe-B oxide powders with various pH were prepared using chloride and nitrate precursors including NdCl3·6H2O, FeCl3·6H2O, H3BO3, Nd2O3, Fe(NO3)3·9H2O, HNO3, citric acid (CA), ethylene glycol (EG) by Pechini type sol-gel method. The pH of chloride and nitrate base sols were 0 and 2.2, respectively. Mixed oxide powders were obtained by calcination and annealing the gels. These oxides by using a reduction-diffusion process under high vacuum and employing CaH2 as reducing agent at 800 °C were hated to prepare Nd2Fe14B nanoparticles. The role of pH on phase, morphologies, microstructure, and magnetic properties of the powders were investigated. The results show that with a decrease in pH, the average particle size and coercivity of Nd-Fe-B oxide powders were decreased and increased, respectively. Nd2Fe14B nanoparticles were formed successfully after reduction process. The average particle size of reduction treated products were 30 and 65 nm for powders which made of chloride and nitrate base metal salts, respectively. Final powders which made of chloride and nitrate base metal salts had a saturation magnetization of 127.7 emu/g and 122.8 emu/g while the coercivity of samples were 3.32 kOe and 1.82 kOe, respectively. The experimental results in the angular dependence of coercivity indicated that the normalized coercivity of the permanent magnets Hc(θ)/Hc(0) obeys the 1/cosθ law and intermediate between the 1/cosθ law and Stoner-Wohlfarth formula for different Nd2Fe14B magnets which made of nitrate and chloride base metal salts, respectively. Also, the results show that different Nd2Fe14B magnets which made of nitrate and chloride base metal salts had the maximum energy product of 5 and 16 MGOe, respectively. The Henkel plot showed that magnetic phases in synthesized NdFeB magnets which made of chloride and nitrate base metal salts were coupled by exchange and dipolar interactions, respectively. Different average particle size, morphology and microstructure were the reasons for variation of magnetic properties.

Using mineral geochemistry to decipher slab, mantle, and crustal input in the generation of high-Mg andesites and basaltic andesites from the northern Cascade Arc

USGS Publications Warehouse

Sas, May; DeBari, Susan; Clynne, Michael A.; Rusk, Brian G.

2017-01-01

To better understand the role of slab melt in the petrogenesis of North Cascades magmas, this study focuses on petrogenesis of high-Mg lavas from the two northernmost active volcanoes in Washington. High-Mg andesites (HMA) and basaltic andesites (HMBA) in the Cascade Arc have high Mg# [molar Mg/(Mg+Fe2+)] relative to their SiO2 contents, elevated Nd/Yb, and are Ni- and Cr-enriched. The rock units examined here include the Tarn Plateau HMBA (51.8–54.0 wt% SiO2, Mg# 68–70) and Glacier Creek HMA (58.3–58.7 wt% SiO2, Mg# 63–64) from the Mount Baker Volcanic Field, and the Lightning Creek HMBA (54.8–54.6 SiO2, Mg# 69–73) from Glacier Peak. This study combines major and trace element compositions of minerals and whole rocks to test several petrogenetic hypotheses and to determine which, if any, are applicable to North Cascades HMA and HMBA. In the Tarn Plateau HMBA, rare earth element (REE) equilibrium liquids calculated from clinopyroxene compositions have high Nd/Yb that positively correlates with Mg#. This correlation suggests an origin similar to that proposed for Aleutian adakites, where intermediate, high Nd/Yb slab-derived melts interact with the overlying mantle to become Mg-rich, and subsequently mix with low Nd/Yb, mantle-derived mafic magmas with lower Mg#. In the Glacier Creek HMA, elevated whole-rock MgO and SiO2 contents resulted from accumulation of xenocrystic olivine and differentiation processes, respectively, but the cause of high Nd/Yb is less clear. However, high whole-rock Sr/P (fluid mobile/fluid immobile) values indicate a mantle source that was fluxed by an enriched, hydrous slab component, likely producing the observed high Nd/Yb REE signature. The Lightning Creek HMBA is a hybridized rock unit with at least three identifiable magmatic components, but only one of which has HMA characteristics. Cr and Mg contents in Cr-spinel and olivine pairs in this HMA component suggest that its source is a strongly depleted mantle, and high whole-rock Sr/P values indicate mantle melting that was induced through hydration, likely adding the component responsible for the observed high Nd/Yb REE pattern. The elevated SiO2 contents (54.6 wt%) of the HMA component resulted from differentiation or high degrees of partial melting of ultramafic material through the addition of H2O. Therefore the Lightning Creek HMBA is interpreted to have originated from a refractory mantle source that underwent melting through interaction with an enriched slab component. Our results indicate that in addition to slab-derived fluids, slab-derived melts also have an important role in the production of HMA and HMBA in the north Cascade Arc.

Low-threshold, CW, all-solid-state Ti:Al2O3 laser

NASA Technical Reports Server (NTRS)

Harrison, James; Finch, Andrew; Rines, David M.; Rines, Glen A.; Moulton, Peter F.

1991-01-01

A CW Ti:Al2O3 ring laser with a threshold power of 119 mW is demonstrated. It provides a tunable source of single-frequency, diffraction-limited radiation that is suitable for injection seeding. The Ti:Al2O3 laser is operated with a diode-laser-pumped, frequency-doubled, Nd:YAG laser as the sole pump source.

182W and HSE constraints from 2.7 Ga komatiites on the heterogeneous nature of the Archean mantle

NASA Astrophysics Data System (ADS)

Puchtel, Igor S.; Blichert-Toft, Janne; Touboul, Mathieu; Walker, Richard J.

2018-05-01

While the isotopically heterogeneous nature of the terrestrial mantle has long been established, the origin, scale, and longevity of the heterogeneities for different elements and isotopic systems are still debated. Here, we report Nd, Hf, W, and Os isotopic and highly siderophile element (HSE) abundance data for the Boston Creek komatiitic basalt lava flow (BCF) in the 2.7 Ga Abitibi greenstone belt, Canada. This lava flow is characterized by strong depletions in Al and heavy rare earth elements (REE), enrichments in light REE, and initial ε143Nd = +2.5 ± 0.2 and intial ε176Hf = +4.2 ± 0.9 indicative of derivation from a deep mantle source with time-integrated suprachondritic Sm/Nd and Lu/Hf ratios. The data plot on the terrestrial Nd-Hf array suggesting minimal involvement of early magma ocean processes in the fractionation of lithophile trace elements in the mantle source. This conclusion is supported by a mean μ142Nd = -3.8 ± 2.8 that is unresolvable from terrestrial standards. By contrast, the BCF exhibits a positive 182W anomaly (μ182W = +11.7 ± 4.5), yet is characterized by chondritic initial γ187Os = +0.1 ± 0.3 and low inferred source HSE abundances (35 ± 5% of those estimated for the present-day Bulk Silicate Earth, BSE). Collectively, these characteristics are unique among Archean komatiite systems studied so far. The deficit in the HSE, coupled with the chondritic Os isotopic composition, but a positive 182W anomaly, are best explained by derivation of the parental BCF magma from a mantle domain characterized by a predominance of HSE-deficient, differentiated late accreted material. According to the model presented here, the mantle domain that gave rise to the BCF received only ∼35% of the present-day HSE complement in the BSE before becoming isolated from the rest of the convecting mantle until the time of komatiite emplacement at 2.72 Ga. These new data provide strong evidence for a highly heterogeneous Archean mantle in terms of absolute HSE abundances and W isotopic composition, and also indicate slow mixing, on a timescale of at least 1.8 billion years. Additionally, the data are consistent with a stagnant-lid plate tectonic regime in the Hadean and Archean, prior to the onset of modern-style plate tectonics.

The Northwest Africa 8159 martian meteorite: Expanding the martian sample suite to the early Amazonian

DOE PAGES

Herd, Christopher D. K.; Walton, Erin L.; Agee, Carl B.; ...

2017-09-01

Northwest Africa (NWA) 8159 is an augite-rich shergottite, with a mineralogy dominated by Ca-, Fe-rich pyroxene, plagioclase, olivine, and magnetite. NWA 8159 crystallized from an evolved melt of basaltic composition under relatively rapid conditions of cooling, likely in a surface lava flow or shallow sill. Redox conditions experienced by the melt shifted from relatively oxidizing (with respect to known Martian lithologies, ~QFM) on the liquidus to higher oxygen fugacity (~QFM + 2) during crystallization of the groundmass, and under subsolidus conditions. This shift resulted in the production of orthopyroxene and magnetite replacing olivine phenocryst rims. NWA 8159 contains both crystallinemore » and shock-amorphized plagioclase (An 50–62), often observed within a single grain; based on known calibrations we bracket the peak shock pressure experienced by NWA 8159 to between 15 and 23 GPa. The bulk composition of NWA 8159 is depleted in LREE, as observed for Tissint and other depleted shergottites; however, NWA 8159 is distinct from all other martian lithologies in its bulk composition and oxygen fugacity. Here, we obtain a Sm-Nd formation age of 2.37 ± 0.25 Ga for NWA 8159, which represents an interval in Mars geologic time which, until recently, was not represented in the other martian meteorite types. The bulk rock 147Sm/ 144Nd value of 0.37 ± 0.02 is consistent with it being derived directly from its source and the high initial ε 143Nd value indicates this source was geochemically highly depleted. Cr, Nd, and W isotopic compositions further support a unique mantle source. While the rock shares similarities with the 2.4-Ga NWA 7635 meteorite, there are notable distinctions between the two meteorites that suggest differences in mantle source compositions and conditions of crystallization. Nevertheless, the two samples may be launch-paired. Finally, NWA 8159 expands the known basalt types, ages and mantle sources within the Mars sample suite to include a second igneous unit from the early Amazonian.« less

The Northwest Africa 8159 martian meteorite: Expanding the martian sample suite to the early Amazonian

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

Herd, Christopher D. K.; Walton, Erin L.; Agee, Carl B.

Northwest Africa (NWA) 8159 is an augite-rich shergottite, with a mineralogy dominated by Ca-, Fe-rich pyroxene, plagioclase, olivine, and magnetite. NWA 8159 crystallized from an evolved melt of basaltic composition under relatively rapid conditions of cooling, likely in a surface lava flow or shallow sill. Redox conditions experienced by the melt shifted from relatively oxidizing (with respect to known Martian lithologies, ~QFM) on the liquidus to higher oxygen fugacity (~QFM + 2) during crystallization of the groundmass, and under subsolidus conditions. This shift resulted in the production of orthopyroxene and magnetite replacing olivine phenocryst rims. NWA 8159 contains both crystallinemore » and shock-amorphized plagioclase (An 50–62), often observed within a single grain; based on known calibrations we bracket the peak shock pressure experienced by NWA 8159 to between 15 and 23 GPa. The bulk composition of NWA 8159 is depleted in LREE, as observed for Tissint and other depleted shergottites; however, NWA 8159 is distinct from all other martian lithologies in its bulk composition and oxygen fugacity. Here, we obtain a Sm-Nd formation age of 2.37 ± 0.25 Ga for NWA 8159, which represents an interval in Mars geologic time which, until recently, was not represented in the other martian meteorite types. The bulk rock 147Sm/ 144Nd value of 0.37 ± 0.02 is consistent with it being derived directly from its source and the high initial ε 143Nd value indicates this source was geochemically highly depleted. Cr, Nd, and W isotopic compositions further support a unique mantle source. While the rock shares similarities with the 2.4-Ga NWA 7635 meteorite, there are notable distinctions between the two meteorites that suggest differences in mantle source compositions and conditions of crystallization. Nevertheless, the two samples may be launch-paired. Finally, NWA 8159 expands the known basalt types, ages and mantle sources within the Mars sample suite to include a second igneous unit from the early Amazonian.« less

Experimental comparative study on morphological effects of different lasers on the liver.

PubMed

Godlewski, G; Miro, L; Chevalier, J M; Bureau, J P

1982-01-01

Three types of laser radiation were compared as to their capabilities in hepatic surgery using 17 New Zealand rabbits. In four animals, subtotal scalpel lobectomy was performed, the hepatic pedicle being clamped. Hemostasis is obtained by means of argon or Nd YAG laser as long as the internal diameter of the vessels encountered is less than 4.5 mm. Nd YAG laser requires a power output four times higher than argon laser to obtain hemostasis. In six animals limited resection was performed by means of Nd YAG and CO2 lasers. CO2 radiation supplied insufficient hemostasis whenever the vessel diameter was more than 1 mm despite an excellent cutting power. Nd YAG radiation created an important necrosis zone due to thermal diffusion. In seven animals various focal hepatic lesions produced by the three types of laser were compared. Argon laser induced superficial and regularly round lesion, Nd YAG laser deeper, cauliflower-like lesions with thermal diffusion following especially vessels. Veins presented thrombosis of their blood content and coagulation necrosis of their wall. The amount of glycogenic granulation decreased. The CO2 laser induced very sharp punctual lesion without necrosis. Electron-microscopic sections revealed faint shadowy liver cells closet to the thermal source and bubbled mitochondria containing disrupted critea around the lesion. In later lesions Nd YAG laser produced more extensive fibrosis than argon or CO2 laser. After first clinical trials we believe that laser irradiation is actually an adjuvant safety factor in current hepatic surgery, whereas the Nd YAG laser could be of real interest in metastatic carcinoma destruction in liver.

Geochemical characterization of critical dust source regions in the American West

NASA Astrophysics Data System (ADS)

Aarons, Sarah M.; Blakowski, Molly A.; Aciego, Sarah M.; Stevenson, Emily I.; Sims, Kenneth W. W.; Scott, Sean R.; Aarons, Charles

2017-10-01

The generation, transport, and deposition of mineral dust are detectable in paleoclimate records from land, ocean, and ice, providing valuable insight into earth surface conditions and cycles on a range of timescales. Dust deposited in marine and terrestrial ecosystems can provide critical nutrients to nutrient-limited ecosystems, and variations in dust provenance can indicate changes in dust production, sources and transport pathways as a function of climate variability and land use change. Thus, temporal changes in locations of dust source areas and transport pathways have implications for understanding interactions between mineral dust, global climate, and biogeochemical cycles. This work characterizes dust from areas in the American West known for dust events and/or affected by increasing human settlement and livestock grazing during the last 150 years. Dust generation and uplift from these dust source areas depends on climate and land use practices, and the relative contribution of dust has likely changed since the expansion of industrialization and agriculture into the western United States. We present elemental and isotopic analysis of 28 potential dust source area samples analyzed using Thermal Ionization Mass Spectrometry (TIMS) for 87Sr/86Sr and 143Nd/144Nd composition and Multi-Collector Inductively Coupled Plasma Mass Spectrometer (MC-ICPMS) for 176Hf/177Hf composition, and ICPMS for major and trace element concentrations. We find significant variability in the Sr, Nd, and Hf isotope compositions of potential source areas of dust throughout western North America, ranging from 87Sr/86Sr = 0.703699 to 0.740236, εNd = -26.6 to 2.4, and εHf = -21.7 to -0.1. We also report differences in the trace metal and phosphorus concentrations in the geologic provinces sampled. This research provides an important resource for the geochemical tracing of dust sources and sinks in western North America, and will aid in modeling the biogeochemical impacts of increased dust generation and deposition caused by higher drought frequency and human activity.

Direct Functionalization of an Acid-Terminated Nanodiamond with Azide: Enabling Access to 4-Substituted-1,2,3-Triazole-Functionalized Particles

DOE PAGES

Kennedy, Zachary C.; Barrett, Christopher A.; Warner, Marvin G.

2017-03-01

Azides on the periphery of nanodiamond materials (ND) are of great utility because they have been shown to undergo Cu-catalyzed and Cu-free cycloaddition reactions with structurally diverse alkynes, affording particles tailored for applications in biology and materials science. However, current methods employed to access ND featuring azide groups typically require either harsh pretreatment procedures or multiple synthesis steps and use surface linking groups that may be susceptible to undesirable cleavage. Here in this paper we demonstrate an alternative single-step approach to producing linker-free, azide-functionalized ND. Our method was applied to low-cost, detonation-derived ND powders where surface carbonyl groups undergo silver-mediatedmore » decarboxylation and radical substitution with azide. ND with directly grafted azide groups were then treated with a variety of aliphatic, aromatic, and fluorescent alkynes to afford 1-(ND)-4-substituted-1,2,3-triazole materials under standard copper-catalyzed cycloaddition conditions. Surface modification steps were verified by characteristic infrared absorptions and elemental analyses. High loadings of triazole surface groups (up to 0.85 mmol g –1) were obtained as determined from thermogravimetric analysis. The azidation procedure disclosed is envisioned to become a valuable initial transformation in numerous future applications of ND.« less

Inference of segmented color and texture description by tensor voting.

PubMed

Jia, Jiaya; Tang, Chi-Keung

2004-06-01

A robust synthesis method is proposed to automatically infer missing color and texture information from a damaged 2D image by (N)D tensor voting (N > 3). The same approach is generalized to range and 3D data in the presence of occlusion, missing data and noise. Our method translates texture information into an adaptive (N)D tensor, followed by a voting process that infers noniteratively the optimal color values in the (N)D texture space. A two-step method is proposed. First, we perform segmentation based on insufficient geometry, color, and texture information in the input, and extrapolate partitioning boundaries by either 2D or 3D tensor voting to generate a complete segmentation for the input. Missing colors are synthesized using (N)D tensor voting in each segment. Different feature scales in the input are automatically adapted by our tensor scale analysis. Results on a variety of difficult inputs demonstrate the effectiveness of our tensor voting approach.

Laser Demonstration of Diode-Pumped Nd3+-Doped Fluorapatite Anisotropic Ceramics

NASA Astrophysics Data System (ADS)

Akiyama, Jun; Sato, Yoichi; Taira, Takunori

2011-02-01

We report the first demonstration of a diode-pumped anisotropic ceramic laser that uses microdomain-controlled neodymium-doped hexagonal fluorapatite [Nd3+:Ca10(PO4)6F2, Nd:FAP] polycrystalline ceramics as the gain medium, which were fabricated by the rare-earth-assisted magnetic grain-orientation control method, as a step toward achieving giant micro photonics. The laser delivers 1063.10 and 1063.22 nm output beams when pumped with a central wavelength of 807.5 nm and a 2 nm bandwidth diode laser operating in quasi-continuous-wave (QCW) mode. We obtained a maximum QCW peak power of 255 mW with an uncoated 2 at. % Nd:FAP material.

An alternative method for determining daily bladder perception.

PubMed

Erdem, Erim; Karazindiyanoglu, Sinan; Ulger, Suleyman

2010-01-01

To avoid the unphysiologic nature of cystometry, we searched a new tool for evaluating bladder perceptions. The study group consisted of 25 (14 girls and 11 boys) primary monosymptomatic enuretic children with a mean age of 11 (range 8-16). Four children were excluded due to neuromuscular dysfunctions of the bladder, which was demonstrated with the help of cystometry. All children filled a voiding chart 3 times daily to record the duration elapsed till normal desire (ND(daily)) and strong desire (SD(daily)). During cystometry, the amounts of infused medium (cystometric ND(ml) and cystometric SD(ml)) and the duration (cystometric ND(sec) and cystometric SD(sec)), till ND and SD were perceived and recorded. Mean cystometric ND(ml) was 209.9 +/- 107.2 and ND(sec), 318.1 +/- 135.5, whereas mean cystometric SD(ml) was 273.0 +/- 103.1 and SD(sec), 415.7 +/- 136.8. To evaluate the reliability of elapsed time instead of milliliters, as a parameter, cystometric ND/SD values were calculated and a strong correlation was found between the 2 (ND/SD(sec) = 0.77 +/- 0.19 and ND/SD(ml) = 0.77 +/- 0.19, r = 0.9795, P = .000). Although there was a strong correlation between 3 ND(daily) (r = 0.9576, P = .000), between 3 SD(daily) (r = 0.9706, P = .000), and 3 ND/SD(daily) (r = 0.8706, P = .000), no significant correlation was determined between mean ND(daily) and cystometric ND(sec) (r = 0.3410, P = .2032), and also between mean SD(daily) and cystometric SD(sec) (r = 0.2740, P = .2402). Daily durations of sensations do not correlate with those perceived during cystometry. However, as the results of 3 consecutive daily recordings have a strong correlation, comparison of the reliability of these methods is still needed. 2010 Elsevier Inc. All rights reserved.

Lanthanide (Nd, Gd) compounds with garnet and monazite structures. Powders synthesis by "wet" chemistry to sintering ceramics by Spark Plasma Sintering

NASA Astrophysics Data System (ADS)

Potanina, Ekaterina; Golovkina, Ludmila; Orlova, Albina; Nokhrin, Aleksey; Boldin, Maksim; Sakharov, Nikita

2016-05-01

Complex oxide Y2.5Nd0.5Al5O12 with garnet structure and phosphates NdPO4 and GdPO4 with monazite structure were obtained by using precipitation methods. Ceramics Y2.5Nd0.5Al5O12 and NdPO4 were processed by Spark Plasma Sintering (SPS). Relative density more 98%, sintering time did not exceed 8 min, sintering temperature 1330-1390 °C. Leaching rates of elements from ceramics were 10-6-10-7 g/(cm2 d). The process of ceramics sintering has two-stage character: the first step of sintering-compaction process is related to the plastic flow of the material, the second step-to the process of grain boundary diffusion and grain growth.

Changes in Sediment Provenance to the Southeast Newfoundland Ridge from the late Eocene to the Early Oligocene; Northern Hemisphere Glaciation or Deep Water Circulation?

NASA Astrophysics Data System (ADS)

Scher, H. D.; Romans, B.; Moffett, Z. J.; Buckley, W. P.; Gibson, K.

2013-12-01

We report radiogenic isotope results from IODP Site U1411 (41° 37.10' N; 48° 59.98' W; 3300 m) on the Southeast Newfoundland Ridge (SENR) that span the Eocene Oligocene Transition (EOT). Neodymium (Nd) and strontium (Sr) isotope compositions of decarbonated and acid-reduced bulk sediments (i.e., the terrigenous fraction) are consistent with sources from ancient cratons on the Canadian, Greenland, and Fennoscandian shields. Down-core Nd isotope records were generated from the terrigenous fraction and fossil fish teeth at a resolution of 50 kyr spanning the late Eocene to the early Oligocene (ca. 37.5 to 32 Ma). The Nd isotope record of the terrigenous fraction reveals variability on two time scales. First, a long-term shift to less radiogenic ɛNd values occurs from the late Eocene to the early Oligocene. In the late Eocene the baseline ɛNd value is -14 and decreases to -18 in the early Oligocene. The main phase of the long-term shift begins after 34.6 Ma. Second, there are two short-lived excursions toward less radiogenic ɛNd values during the Eocene. Both excursions are on the order of 200 - 300 kyr and involve a shift from the late Eocene baseline ɛNd value of -14 to -18. The older excursion is from 37.3 to 37.0 Ma and the younger excursion from 36.2 to 36.0 Ma. The fossil fish tooth Nd isotope record indicates that the source of Nd to bottom waters at U1411 did not change over the investigated interval. Fossil fish tooth ɛNd values average -10.3 × 0.8 ɛNd (2σ, n=75). This level of ɛNd variability is very low compared to other Nd isotope records spanning the EOT. Both the long and short-term terrigenous ɛNd variability indicates changes in sediment provenance to the study site. A change in sediment provenance can be attributed to either 1) a change in the strength or position of the Deep Western Boundary Current that supplies sediment to the site or 2) an influx of sediment to the North Atlantic resulting from enhanced weathering/erosion on adjacent continents. There is not a long term trend nor prominent inflections in the fossil fish tooth ɛNd record that are associated with terrigenous ɛNd values so it does not appear likely that changes in sediment provenance were accompanied by a reorganization of deep water masses. Thus the preliminary results are cautiously interpreted as reflecting a sedimentological response to an overall increase in weathering/erosion of ancient continental crust, possibly on Greenland, over the investigated interval. In this context these results may reflect the emplacement of northern hemisphere ice sheets in the latest Eocene, preceded by prominent short-lived glacial events in the Eocene. The first short-lived event falls within polarity chron C17n.1n, which corresponds with the timing of a known Eocene glaciation on Antarctica and suggests that the greenhouse climate in the late Eocene supported a bipolar glacial event. We are currently generating a record of relative paleo-bottom current intensity from U1411 using the sortable silt proxy to further evaluate the role of bottom currents in terrigenous sediment provenance on the SENR.

Enterprise Terrain Data Standards for Joint Training

DTIC Science & Technology

2017-10-03

e.g., bombs /shells, vehicles, etc.) or environmental factors (e.g., weather). • Riverine and ocean surface and bathymetry. o Wave/swell generation...Attachment 2 Terrain Generation Capability St an da rd iz ed S ch em a & At tr ib ut es...F or m at Pl at fo rm In de pe nd en t O pe ra tin g Sy st em In de pe nd en t Geospatial Source & Industry Formats Utilized by the Specification

Duration of a Magma Ocean and Subsequent Mantle Overturn in Mars: Evidence from Nakhlites

NASA Technical Reports Server (NTRS)

Debaille, V.; Brandon, A. D.; Yin, Q.-Z.; Jacobsen, B.

2008-01-01

It is now generally accepted that the heat produced by accretion, short-lived radioactive elements such as Al-26, and gravitational energy from core formation was sufficient to at least partially melt the silicate portions of terrestrial planets resulting in a global-scale magma ocean. More particularly, in Mars, the geochemical signatures displayed by shergottites, are likely inherited from the crystallization of this magma ocean. Using the short-lived chronometer Sm-146 - Nd-142 (t(sup 1/2) = 103 Myr), the duration of the Martian magma ocean (MMO) has been evaluated to being less than 40 Myr, while recent and more precise ND-142/ND-144 data were used to evaluate the longevity of the MMO to approximately 100 Myr after the solar system formation. In addition, it has been proposed that the end of the crystallization of the MMO may have triggered a mantle overturn, as a result of a density gradient in the cumulate layers crystallized at different levels. Dating the mantle overturn could hence provide additional constraint on the duration of the MMO. Among SNC meteorites, nakhlites are characterized by high epsilon W-182 of approximately +3 and an epsilon Nd-142 similar to depleted shergottites of +0.6-0.9. It has hence been proposed that the source of nakhlites was established very early in Mars history (approximately 8-10 Myr). However, the times recorded in HF-182-W-182 isotope system, i.e. when 182Hf became effectively extinct (approximately 50 Myr after solar system formation) are less than closure times recorded in the Sm-146-Nd-142 isotope system (with a full coverage of approximately 500 Myr after solar system formation). This could result in decoupling between the present-day measured epsilon W-182 and epsilon Nd-142 as the SM-146 may have recorded later differentiation events in epsilon ND-142 not observed in epsilon W-182 values. With these potential complexities in short-lived chronological data for SNC's in mind, new Hf-176/Hf-177, Nd-143/Nd-144 and Nd-142/Nd-144 were obtained for three nakhlites (Nakhla, MIL03346 and Yamato000593). These new data are combined with previous epsilon W-182 data, to investigate potential discrepancies between the Hf-182-W-182 and Sm-146-Nd-142 systematics, and the relationship between the source of nakhlites and a crystallizing magma ocean

Occurrence and profiling of multiple nitrosamines in source water and drinking water of China.

PubMed

Wang, Wanfeng; Yu, Jianwei; An, Wei; Yang, Min

2016-05-01

The occurrence of multiple nitrosamines was investigated in 54 drinking water treatment plants (DWTPs) from 30 cities across major watersheds of China, and the formation potential (FP) and cancer risk of the dominant nitrosamines were studied for profiling purposes. The results showed that N-nitrosodimethylamine (NDMA), N-nitrosodiethylamine (NDEA) and N-nitrosodi-n-butylamine (NDBA) were the most abundant in DWTPs, and the concentrations in source water and finished water samples were not detected (ND) -53.6ng/L (NDMA), ND -68.5ng/L (NDEA), ND -48.2ng/L (NDBA). The frequencies of detection in source waters were 64.8%, 61.1% and 51.8%, and 57.4%, 53.7%, and 37% for finished waters, respectively. Further study indicated that the FPs of the three main nitrosamines during chloramination were higher than those during chlorination and in drinking water. The results of Principal Components Analysis (PCA) showed that ammonia was the most closely associated factor in nitrosamine formation in the investigated source water; however, there was no significant correlation between nitrosamine-FPs and the values of dominant water-quality parameters. The advanced treatment units (i.e., ozonation and biological activated carbon) used in DWTPs were able to control the nitrosamine-FPs effectively after disinfection. The target pollutants posed median and maximum cancer risks of 2.99×10(-5) and 35.5×10(-5) to the local populations due to their occurrence in drinking water. Copyright © 2016 Elsevier B.V. All rights reserved.

The history of a continent from U-Pb ages of zircons from Orinoco River sand and Sm-Nd isotopes in Orinoco basin river sediments

USGS Publications Warehouse

Goldstein, S.L.; Arndt, N.T.; Stallard, R.F.

1997-01-01

We report SHRIMP U-Pb ages of 49 zircons from a sand sample from the lower Orinoco River, Venezuela, and Nd model ages of the fine sediment load from the main river and tributaries. The U-Pb ages reflect individual magmatic or metamorphic events, the Sm-Nd model ages reflect average crustal-residence ages of the sediment sources. Together they allow delineation of the crust-formation history of the basement precursors of the sediments. The U-Pb ages range from 2.83 to 0.15 Ga, and most are concordant or nearly so. Discrete age groupings occur at ??? 2.8, ??? 2.1, and ??? 1.1 Ga. The oldest group contains only three samples but is isolated from its closest neighbors by a ??? 600 Ma age gap. Larger age groupings at ??? 2.1 and ??? 1.1 Ga make up about a third and a quarter of the total number of analyses, respectively. The remaining analyses scatter along concordia, and most are younger than 1.6 Ga. The ??? 2.8 and ??? 2.1 Ga ages correspond to periods of crust formation of the Imataca and Trans-Amazonian provinces of the Guyana Shield, respectively, and record intervals of short but intensive continental growth. These ages coincide with ??? 2.9 and ??? 2.1 Ga Nd model ages of sediments from tributaries draining the Archean and Proterozoic provinces of the Guyana Shield, respectively, indicating that the U-Pb ages record the geological history of the crystalline basement of the Orinoco basin. Zircons with ages corresponding to the major orogenies of the North Atlantic continents (the Superior at ??? 2.7 Ga and Hudsonian at 1.7-1.9 Ga) were not found in the Orinoco sample. The age distribution may indicate that South and North America were separated throughout their history. Nd model ages of sediments from the lower Orinoco River and Andean tributaries are ??? 1.9 Ga, broadly within the range displayed by major rivers and dusts. This age does not coincide with known thermal events in the region and reflects mixing of sources with different crust-formation ages. The igneous and metamorphic history of these sources, as recorded by the detrital zircons, is that of the Orinoco basin basement. This implies that, despite evidence of fast sedimentary recycling, global similarities in Nd crustal-residence ages, and the probability of cross-continent mixing through continental drift, the sedimentary material carried by individual rivers is mainly derived from the crystalline basement in the basin. The global semblance in Nd isotope ratios in major river sediments and atmospheric dusts results from the averaging effect of large-scale sampling of the continents, which are heterogeneous in age on smaller regional scales. A large portion of the continental crust in the Orinoco basin formed during the Trans-Amazonian orogeny at 2.0-2.1 Ga, and smaller portions formed both earlier, at ??? 2.8 Ga, and later, after 1.6 Ga. These observations, which are consistent with the relative sizes of crustal age provinces in the Orinoco basin, indicate that sediments from the lower Orinoco and Andean tributaries contain 25-35% of material added to the crust since Trans-Amazonian times. Nd model ages of these sediments underestimate the average crust-formation age of the basement of the Orinoco basin by only about 10%. If this relationship holds in other river basins, then Nd model ages of major rivers and wind blown particulates indicate that the mean age of the continental crust is ??? 1.9-2 Ga. ?? 1997 Elsevier Science B.V.

Ultrafast-based projection-reconstruction three-dimensional nuclear magnetic resonance spectroscopy.

PubMed

Mishkovsky, Mor; Kupce, Eriks; Frydman, Lucio

2007-07-21

Recent years have witnessed increased efforts toward the accelerated acquisition of multidimensional nuclear magnetic resonance (nD NMR) spectra. Among the methods proposed to speed up these NMR experiments is "projection reconstruction," a scheme based on the acquisition of a reduced number of two-dimensional (2D) NMR data sets constituting cross sections of the nD time domain being sought. Another proposition involves "ultrafast" spectroscopy, capable of completing nD NMR acquisitions within a single scan. Potential limitations of these approaches include the need for a relatively slow 2D-type serial data collection procedure in the former case, and a need for at least n high-performance, linearly independent gradients and a sufficiently high sensitivity in the latter. The present study introduces a new scheme that comes to address these limitations, by combining the basic features of the projection reconstruction and the ultrafast approaches into a single, unified nD NMR experiment. In the resulting method each member within the series of 2D cross sections required by projection reconstruction to deliver the nD NMR spectrum being sought, is acquired within a single scan with the aid of the 2D ultrafast protocol. Full nD NMR spectra can thus become available by backprojecting a small number of 2D sets, collected using a minimum number of scans. Principles, opportunities, and limitations of the resulting approach, together with demonstrations of its practical advantages, are here discussed and illustrated with a series of three-dimensional homo- and heteronuclear NMR correlation experiments.

Optical properties of Nd3+ doped bismuth zinc borate glasses

NASA Astrophysics Data System (ADS)

Shanmugavelu, B.; Venkatramu, V.; Ravi Kanth Kumar, V. V.

2014-03-01

Glasses with compositions of (100-x) (Bi2ZnOB2O6) - x Nd2O3 (where x = 0.1, 0.3, 0.5, 1 and 2 mol%) were prepared by melt quenching method and characterized through optical absorption, emission and decay curve measurements. Optical absorption spectra have been analyzed using Judd-Ofelt theory. The emission spectra exhibit three peaks at 919, 1063 and 1337 nm corresponding to 4F3/2 to 4I9/2, 4I11/2 and 4I13/2 transitions in the near infrared region. The emission intensity of the 4F3/2 to 4I11/2 transition increases with increase of Nd3+ concentration up to 1 mol% and then concentration quenching is observed for 2 mol% of Nd3+ concentration. The lifetimes for the 4F3/2 level are found to decrease with increase in Nd2O3 concentration in the glasses. The decay curves of the glass up to 0.3 mol% of Nd3+ exhibit single exponential nature and thereafter the curves become nonexponential nature (0.5, 1 and 2 mol%). The nonexponential curve has been fitted to the Inokuti-Hirayama model to understand the nature of energy transfer process.

Optical properties of Nd3+ doped bismuth zinc borate glasses.

PubMed

Shanmugavelu, B; Venkatramu, V; Ravi Kanth Kumar, V V

2014-03-25

Glasses with compositions of (100-x) (Bi2ZnOB2O6) -x Nd2O3 (where x=0.1, 0.3, 0.5, 1 and 2 mol%) were prepared by melt quenching method and characterized through optical absorption, emission and decay curve measurements. Optical absorption spectra have been analyzed using Judd-Ofelt theory. The emission spectra exhibit three peaks at 919, 1063 and 1337 nm corresponding to (4)F3/2 to (4)I9/2, (4)I11/2 and (4)I13/2 transitions in the near infrared region. The emission intensity of the (4)F3/2 to (4)I11/2 transition increases with increase of Nd(3+) concentration up to 1 mol% and then concentration quenching is observed for 2 mol% of Nd(3+) concentration. The lifetimes for the (4)F3/2 level are found to decrease with increase in Nd2O3 concentration in the glasses. The decay curves of the glass up to 0.3 mol% of Nd(3+) exhibit single exponential nature and thereafter the curves become nonexponential nature (0.5, 1 and 2 mol%). The nonexponential curve has been fitted to the Inokuti-Hirayama model to understand the nature of energy transfer process. Copyright © 2013 Elsevier B.V. All rights reserved.

Development of lasers optimized for pumping Ti:Al2O3 lasers

NASA Technical Reports Server (NTRS)

Rines, Glen A.; Schwarz, Richard A.

1994-01-01

Laboratory demonstrations that were completed included: (1) an all-solid-state, broadly tunable, single-frequency, Ti:Al2O3 master oscillator, and (2) a technique for obtaining 'long' (nominally 100- to 200-ns FWHM) laser pulses from a Q-switched, Nd oscillator at energy levels commensurate with straightforward amplification to the joule level. A diode-laser-pumped, Nd:YLF laser with intracavity SHG was designed, constructed, and evaluated. With this laser greater than 0.9 W of CW, output power at 523.5 nm with 10 W of diode-laser pump power delivered to the Nd:YLF crystal was obtained. With this laser as a pump source, for the first time, to our knowledge, an all solid-state, single frequency, Ti:Al203 laser with sufficient output power to injection seed a high-energy oscillator over a 20-nm bandwidth was demonstrated. The pulsed laser work succeeded in demonstrating pulse-stretching in a Q-switched Nd:YAG oscillator. Pulse energies greater than 50-mJ were obtained in pulses with 100- to 200-ns pulsewidths (FWHM).

Scintillation properties of YAlO3 doped with Lu and Nd perovskite single crystals

NASA Astrophysics Data System (ADS)

Akatsuka, Masaki; Usui, Yuki; Nakauchi, Daisuke; Kato, Takumi; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2018-05-01

YAlO3 (YAP) single crystals doped with Lu and Nd were grown by the Floating Zone (FZ) method to evaluate their scintillation properties particularly emissions in the near-infrared (NIR) range. The Nd concentration was fixed to 0 or 1 mol% while the Lu concentration was varied from 0 to 30%. When X-ray was irradiated, the scintillation of Nd-doped samples was observed predominantly at 1064 nm due to 4F3/2 → 4I11/2 transition of Nd3+. In contrast, a weak emission around 700 nm appeared in the samples doped with only Lu, and the emission origin was attributed to defect centers. In the Nd3+-doped samples, the decay time was 94-157 μs due to the 4f-4f transitions of Nd3+ whereas the Lu-doped samples showed signal with the decay time of 1.45-1.54 ms. The emission origin of the latter signal was attributed to the perovskite lattice defect.

The nature of Mesoarchaean seawater and continental weathering in 2.85 Ga banded iron formation, Slave craton, NW Canada

NASA Astrophysics Data System (ADS)

Haugaard, Rasmus; Ootes, Luke; Creaser, Robert A.; Konhauser, Kurt O.

2016-12-01

Banded iron formations (BIF) have been extensively used as proxies to infer the chemical composition of ancient bulk seawater. However, their proximity to ancient crust suggests that they might also be used to reveal the composition of emergent continental landmass at the time of their deposition. Here we use the combination of geochemistry and Sm-Nd isotopes on a layer-by-layer basis to interpret the relative contributions of hydrothermal, hydrogenous and terrestrial input to one of the oldest documented Superior-type BIF in the world. The ∼2.85 Ga Central Slave Cover Group BIF is deposited within a rift basin related to a continental margin and is found associated with basement gneisses, as well as shoreline and shallow-shelf type facies, such as fuchsitic quartzite and pebble-to-cobble conglomerate, that confirm a near-shore depositional setting for the BIF. The BIF ranges from a pure chemical oxide (magnetite)-silicate (grunerite + actinolite) sediment with low Al2O3 (<1 wt.%) into a mixture of chemical and clastic sediment characterized by higher Al2O3 (⩽10 wt.%) and the occurrence of ferro-hornblende, biotite and garnet. The silica bands have low trace metal content (e.g., Ni), low ∑REE (average of 6 ppm) and a shale-normalized rare earth and yttrium (REY) pattern that is HREE-to-LREE enriched with (Pr/Yb)SN values reaching <0.2. The iron bands are more enriched, with average ∑REE of 26 and with a more uniform and less fractionated REY pattern (average (Pr/Yb)SN of 0.5). During active rifting of the basement, excess of Eu2+ impacted the basin yielding seawater with Eu anomalies [(Eu/Eu∗)SN] as high as 3.85 (average 2.75), larger than similarly-aged BIF. High-resolution geochemistry shows that there is more silica (19.4 wt.% SiO2) in the iron bands than iron (8.7 wt.% Fe2O3) in the silica bands, implying that dissolved Fe2+ came to the BIF site in pulses and that silica likely represents background deposition. Consistently radiogenic εNd(t) values for the iron bands (average +1.7) show that the dissolved REY in the source water during ferric iron precipitation was provided by submarine hydrothermal fluids with relatively uniform 143Nd/144Nd. The silica bands, by contrast, reveal high variation in seawater 143Nd/144Nd as evident from the bimodal εNd(t) distribution with one segment exhibiting negative εNd(t) values averaging -1.1 and another with positive εNd(t) values averaging +2.5. This suggests input of dissolved REY into the upper seawater from weathering of isotopically different crustal components in the source region. Collectively, we speculate that the low REY in the upper seawater and the overall low Ni content implies a highly weathered crustal surface that was unable to contribute a significant dissolved load to the shelf environment.

Sr, Nd, and Pb isotopes of ultramafic xenoliths in volcanic rocks of Eastern China: enriched components EMI and EMII in subcontinental lithosphere

USGS Publications Warehouse

Tatsumoto, M.; Basu, A.R.; Wankang, H.; Junwen, W.; Guanghong, X.

1992-01-01

The UThPb, SmNd, and RbSr isotopic systematics of mafic and ultramafic xenolithic rocks and associated megacrystic inclusions of aluminous augite and garnet, that occur in three alkalic volcanic suites: Kuandian in eastern Liaoning Province, Hanluoba in Hebei Province, and Minxi in western Fujian Province, China are described. In various isotopic data plots, the inclusion data invariably fall outside the isotopic ranges displayed by the host volcanic rocks, testifying to the true xenolithic nature of the inclusions. The major element partitioning data on Ca, Mg, Fe, and Al among the coexisting silicate minerals of the xenoliths establish their growth at ambient mantle temperatures of 1000-1100??C and possible depths of 70-80 km in the subcontinental lithosphere. Although the partitioning of these elements reflects equilibrium between coexisting minerals, equilibria of the Pb, Nd, and Sr isotopic systems among the minerals were not preserved. The disequilibria are most notable with respect to the 206Pb 204Pb ratios of the minerals. On a NdSr isotopic diagram, the inclusion data plot in a wider area than that for oceanic basalts from a distinctly more depleted component than MORB with higher 143Nd 144Nd and a much broader range of 87Sr 86Sr values, paralleling the theoretical trajectory of a sea-water altered lithosphere in NdSr space. The garnets consistently show lower ?? and ?? values than the pyroxenes and pyroxenites, whereas a phlogopite shows the highest ?? and ?? values among all the minerals and rocks studied. In a plot of ??207 and ??208, the host basalts for all three areas show lower ??207 and higher ??208 values than do the xenoliths, indicating derivation of basalts from Th-rich (relative to U) sources and xenoliths from U-rich sources. The xenolith data trends toward the enriched mantle components, EMI and EMII-like, characterized by high 87Sr 86Sr and ??207 values but with slightly higher 143Nd 144Nd. The EMI trend is shown more distinctly by the host basalts. The EMII mantle domain may be present in the Chinese continental lithosphere just above the EMI domain of the basalt source at the lower part of the lithosphere. We argue that the ancient depleted continental lithosphere was metasomatized, imparting the EMI signature, in earlier times ( > 1000 m.y.), and U migrated upward, resulting in high Th U ratios in the lower portion of the lithosphere. Observed high Th U, Rb Sr, 87Sr 86Sr and ??208, low Sm Nd ratios, and a large negative ??Nd in phlogopite pyroxenite with a depleted mantle model age of 2.9 Ga, support our contention that metasomatized continental lower mantle lithosphere is the source for the EMI component. We also suggest that the EMII signature may have been introduced later (less than ??? 500 Ma) by another metasomatic event during the subduction of an oceanic plate, which was partially responsible for some of the observed inter-mineral isotopic disequilibria. ?? 1992.

Petrogenesis of Early Cretaceous granitoids from southwest Zhejiang, NE South China Block and its geodynamic implication

NASA Astrophysics Data System (ADS)

Pan, Fa-Bin; Liu, Rong; Jin, Chong; Jia, Bao-Jian; He, Xiaobo; Gao, Zhong; Tao, Lu; Zhou, Xiao-Chun; Zhang, Li-Qi

2018-05-01

In situ zircon U-Pb ages, whole-rock major and trace elements, and Sr-Nd isotopic compositions of the Sucun, Yunfeng, and Jingning intrusions from southwest Zhejiang, NE South China Block, are presented to trace their petrogenesis and shed light on its lithosphere evolution. LA-ICP-MS U-Pb zircon dating shows that the Sucun quartz monzonite and Jingning monzogranite were emplaced at 135 Ma, and the Yunfeng quartz monzonite and Jingning granite were emplaced at 104 and 112 Ma, respectively. All these intrusions are metaluminous to weakly peraluminous and lie within high-K calc-alkaline to shoshonite series field (SiO2 = 66-76 wt%, A/CNK = 0.95-1.09, K2O/Na2O = 0.78-1.77). The Yunfeng quartz monzonite clearly have lower K2O and total REE contents, and higher CaO, Na2O, Al2O3, P2O5, MgO, and TiO2 contents, and relatively less enriched Sr-Nd isotopic compositions than those of the Sucun quartz monzonite, indicating that the Yunfeng quartz monzonite were derived from partial melting of a more juvenile lower crust sources compared with the magma source of the Sucun quartz monzonite. The Jingning monzogranite exhibit similar major elements covariations and Nd isotopic compositions, but higher Ba, Sr, and Eu contents and lower Rb, Th, and U contents than those of the Jingning granite. The geochemical features imply that the Jingning monzogranite and granite were fluid-present and fluid-absent anatexis products of the same Paleoproterozoic crustal source, respectively. Whole-rock Sr-Nd isotopic data imply that the estimated amounts of juvenile mantle-derived melts input into the mature crust show southeastward decreasing trend away from the Jiangshan-Shaoxing fault. We propose that roll-back and retreat of the Paleo-Pacific subducting plate might cause extensive asthenosphere mantle upwelling in East China, and the mantle-derived melts tend to rise through the regional main fault zones and preferentially modify the lithosphere nearby these faults.

Importance of the Lu-Hf isotopic system in studies of planetary chronology and chemical evolution

USGS Publications Warehouse

Patchett, P.J.

1983-01-01

The 176Lu-176Hf isotope method and its applications in earth sciences are discussed. Greater fractionation of Lu/Hf than Sm/Nd in planetary magmatic processes makes 176Hf 177Hf a powerful geochemical tracer. In general, proportional variations of 176Hf 177Hf exceed those of 143Nd l44Nd by factors of 1.5-3 in terrestrial and lunar materials. Lu-Hf studies therefore have a major contribution to make in understanding of terrestrial and other planetary evolution through time, and this is the principal importance of Lu-Hf. New data on basalts from oceanic islands show unequivocally that whereas considerable divergences occur in 176Hf 177Hf- 87Sr 86Sr and 143Nd l44Nd- 87Sr 86Sr diagrams, 176Hf 177Hf and 143Nd 144Nd display a single, linear isotopic variation in the suboceanic mantle. These discordant 87Sr 86Sr relationships may allow, with the acquisition of further Hf-Nd-Sr isotopic data, a distinction between processes such as mantle metasomatism, influence of seawater-altered material in the magma source, or recycling of sediments into the mantle. In order to evaluate the Hf-Nd isotopic correlation in terms of mantle fractionation history, there is a need for measurements of Hf distribution coefficients between silicate minerals and liquids, and specifically for a knowledge of Hf behavior in relation to rareearth elements. For studying ancient terrestrial Hf isotopic variations, the best quality Hf isotope data are obtained from granitoid rocks or zircons. New data show that very U-Pb discordant zircons may have upwardly-biased 176Hf 177Hf, but that at least concordant to slightly discordant zircons appear to be reliable carriers of initial 176Hf 177Hf. Until the controls on addition of radiogenic Hf to zircon are understood, combined zircon-whole rock studies are recommended. Lu-Hf has been demonstrated as a viable tool for dating of ancient terrestrial and extraterrestrial samples, but because it offers little advantage over existing methods, is unlikely to find wide application in pure chronological studies. ?? 1983.

Design of LaPO4:Nd3+ materials by using ionic liquids

NASA Astrophysics Data System (ADS)

Cybinska, J.; Guzik, M.; Lorbeer, C.; Zych, E.; Guyot, Y.; Boulon, G.; Mudring, A.-V.

2017-01-01

Monoclinic monazite-type Nd3+-doped lanthanum orthophosphate (LaPO4:Nd3+) nanoparticles were prepared by microwave treatment of simple lanthanide precursors such as Nd(OAc)3•xH2O, OAc = acetate) with task-specific dihydrogen phosphate ionic liquids (ILs) 1-butyl-1-methylpyrrolidinium dihydrogenphosphate- BmPyrH2PO4 (IL1) and 2-hydroxyethyl-N,N,N-trimethylammonium, [choline][H2PO4] (IL2) as the reaction medium, reactant and in-situ nanoparticle stabilizer. This synthesis route possesses many advantages as it is a fast and facile preparation method of the desired phosphate nanomaterials without the necessity for post-reaction heat treatment to obtain the anhydrous high temperature monazite phosphate phase. The nano-sized phosphors Nd3+:LaPO4 were carefully analyzed by the powder X-ray diffraction, electron microscopy and spectroscopic techniques taking advantage of the Nd3+ spectroscopic probe to analyze in detail the structural properties. Applied high resolution low temperature absorption and emission techniques allowed to complete the structural information unavailable from the XRD powder patterns. A clear influence of the used task-specific dihydrogen phosphate ILs on the structure, morphology, luminescence intensity and lifetimes of the obtained Nd3+:LaPO4 was found. It is worth noting that the Nd3+ luminescence in LaPO4 has never been reported up to now.

Simplified quantification and whole-body distribution of [18F]FE-PE2I in nonhuman primates: prediction for human studies.

PubMed

Varrone, Andrea; Gulyás, Balázs; Takano, Akihiro; Stabin, Michael G; Jonsson, Cathrine; Halldin, Christer

2012-02-01

[(18)F]FE-PE2I is a promising dopamine transporter (DAT) radioligand. In nonhuman primates, we examined the accuracy of simplified quantification methods and the estimates of radiation dose of [(18)F]FE-PE2I. In the quantification study, binding potential (BP(ND)) values previously reported in three rhesus monkeys using kinetic and graphical analyses of [(18)F]FE-PE2I were used for comparison. BP(ND) using the cerebellum as reference region was obtained with four reference tissue methods applied to the [(18)F]FE-PE2I data that were compared with the kinetic and graphical analyses. In the whole-body study, estimates of adsorbed radiation were obtained in two cynomolgus monkeys. All reference tissue methods provided BP(ND) values within 5% of the values obtained with the kinetic and graphical analyses. The shortest imaging time for stable BP(ND) estimation was 54 min. The average effective dose of [(18)F]FE-PE2I was 0.021 mSv/MBq, similar to 2-deoxy-2-[(18)F]fluoro-d-glucose. The results in nonhuman primates suggest that [(18)F]FE-PE2I is suitable for accurate and stable DAT quantification, and its radiation dose estimates would allow for a maximal administered radioactivity of 476 MBq in human subjects. Copyright © 2012 Elsevier Inc. All rights reserved.

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

Nazareth, A.S.; Sood, D.K.; Zmood, R.B.

A focusing grid broad beam Kaufman source, using argon ions on a target of nominal composition Nd{sub 2}Fe{sub 14}B has been employed to sputter deposit magnetic thin films of thicknesses ranging from 800 {angstrom} to 1300 {angstrom} on silicon-(111) substrates at room temperature. These films were characterized for their composition depth profile by Rutherford Backscattering Spectroscopy, while x-ray diffraction was used to study the crystallographic structure. Due to a close match between (111) Si with (220) Nd{sub 2}Fe{sub 14}B lattice spacings, preferred crystallographic texturing was expected, and experimental results showed a greatly enhanced (220) texture. The degradation in magnetic propertiesmore » was attributed to the presence of oxygen in the films as indicated by concentration depth profiles. It is premised that another significant role of oxygen may be to relieve the misfit strain across the interface by its incorporation within the Nd{sub 2}Fe{sub 14}B phase.« less

New development of laser ion source for highly charged ion beam production at Institute of Modern Physics (invited).

PubMed

Zhao, H Y; Zhang, J J; Jin, Q Y; Liu, W; Wang, G C; Sun, L T; Zhang, X Z; Zhao, H W

2016-02-01

A laser ion source based on Nd:YAG laser has been being studied at the Institute of Modern Physics for the production of high intensity high charge state heavy ion beams in the past ten years, for possible applications both in a future accelerator complex and in heavy ion cancer therapy facilities. Based on the previous results for the production of multiple-charged ions from a wide range of heavy elements with a 3 J/8 ns Nd:YAG laser [Zhao et al., Rev. Sci. Instrum. 85, 02B910 (2014)], higher laser energy and intensity in the focal spot are necessary for the production of highly charged ions from the elements heavier than aluminum. Therefore, the laser ion source was upgraded with a new Nd:YAG laser, the maximum energy of which is 8 J and the pulse duration can be adjusted from 8 to 18 ns. Since then, the charge state distributions of ions from various elements generated by the 8 J Nd:YAG laser were investigated for different experimental conditions, such as laser energy, pulse duration, power density in the focal spot, and incidence angle. It was shown that the incidence angle is one of the most important parameters for the production of highly charged ions. The capability of producing highly charged ions from the elements lighter than silver was demonstrated with the incidence angle of 10° and laser power density of 8 × 10(13) W cm(-2) in the focal spot, which makes a laser ion source complementary to the superconducting electron cyclotron resonance ion source for the future accelerator complex especially in terms of the ion beam production from some refractory elements. Nevertheless, great efforts with regard to the extraction of intense ion beams, modification of the ion beam pulse duration, and reliability of the ion source still need to be made for practical applications.

New development of laser ion source for highly charged ion beam production at Institute of Modern Physics (invited)

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

Zhao, H. Y., E-mail: zhaohy@impcas.ac.cn; Zhang, J. J.; Jin, Q. Y.

2016-02-15

A laser ion source based on Nd:YAG laser has been being studied at the Institute of Modern Physics for the production of high intensity high charge state heavy ion beams in the past ten years, for possible applications both in a future accelerator complex and in heavy ion cancer therapy facilities. Based on the previous results for the production of multiple-charged ions from a wide range of heavy elements with a 3 J/8 ns Nd:YAG laser [Zhao et al., Rev. Sci. Instrum. 85, 02B910 (2014)], higher laser energy and intensity in the focal spot are necessary for the production ofmore » highly charged ions from the elements heavier than aluminum. Therefore, the laser ion source was upgraded with a new Nd:YAG laser, the maximum energy of which is 8 J and the pulse duration can be adjusted from 8 to 18 ns. Since then, the charge state distributions of ions from various elements generated by the 8 J Nd:YAG laser were investigated for different experimental conditions, such as laser energy, pulse duration, power density in the focal spot, and incidence angle. It was shown that the incidence angle is one of the most important parameters for the production of highly charged ions. The capability of producing highly charged ions from the elements lighter than silver was demonstrated with the incidence angle of 10° and laser power density of 8 × 10{sup 13} W cm{sup −2} in the focal spot, which makes a laser ion source complementary to the superconducting electron cyclotron resonance ion source for the future accelerator complex especially in terms of the ion beam production from some refractory elements. Nevertheless, great efforts with regard to the extraction of intense ion beams, modification of the ion beam pulse duration, and reliability of the ion source still need to be made for practical applications.« less

Selective Extraction and Recovery of Nd and Dy from Nd-Fe-B Magnet Scrap by Utilizing Molten MgCl2

NASA Astrophysics Data System (ADS)

Shirayama, Sakae; Okabe, Toru H.

2018-06-01

Fundamental experiments are conducted with the aim of developing an efficient recycling process for rare earth elements (REEs) from neodymium-iron-boron (Nd-Fe-B) permanent magnet scrap. Molten magnesium dichloride (MgCl2) was chosen as an extraction medium, which can selectively chlorinate and extract REEs in magnet alloys. Dysprosium-containing Nd-Fe-B magnet alloy was immersed in molten MgCl2 at 1273 K (1000 °C) for 3 to 12 hours. The results of the experiments clearly show that the REEs in the magnetic alloy were successfully extracted into the molten salt, while the Fe-B alloy remained in a solid form. The extraction ratios of Nd and Dy were at most 87 and 78 mass pct, respectively. After the extraction experiment, excess MgCl2 and Mg were removed by vacuum distillation and the rare earth chlorides were recovered. Thus, the feasibility of this method for efficient recovery of rare earths using molten MgCl2 is demonstrated.

Selective Extraction and Recovery of Nd and Dy from Nd-Fe-B Magnet Scrap by Utilizing Molten MgCl2

NASA Astrophysics Data System (ADS)

Shirayama, Sakae; Okabe, Toru H.

2018-02-01

Fundamental experiments are conducted with the aim of developing an efficient recycling process for rare earth elements (REEs) from neodymium-iron-boron (Nd-Fe-B) permanent magnet scrap. Molten magnesium dichloride (MgCl2) was chosen as an extraction medium, which can selectively chlorinate and extract REEs in magnet alloys. Dysprosium-containing Nd-Fe-B magnet alloy was immersed in molten MgCl2 at 1273 K (1000 °C) for 3 to 12 hours. The results of the experiments clearly show that the REEs in the magnetic alloy were successfully extracted into the molten salt, while the Fe-B alloy remained in a solid form. The extraction ratios of Nd and Dy were at most 87 and 78 mass pct, respectively. After the extraction experiment, excess MgCl2 and Mg were removed by vacuum distillation and the rare earth chlorides were recovered. Thus, the feasibility of this method for efficient recovery of rare earths using molten MgCl2 is demonstrated.

Structure and magnetic properties of Nd2Fe14B fine particles produced by spark erosion

NASA Astrophysics Data System (ADS)

Wan, H.; Berkowitz, A. E.

1994-11-01

At present Nd2Fe14B is the best permanent magnet because of its extremely high coercivity and energy product. Optimum properties of Nd2Fe14B magnets can be attained by producing single domain particles, and then aligning and compacting them. Due to the reactivity of the Nd constitutent, it is challenging to produce and handle a large amount of fine particles of this material. We have prepared fine particles of Nd2Fe14B by spark erosion with various dielectric media. Yield, size, size distribution, structure, and magnetic properties are discussed. The Nd2Fe14B particles were made by the sharker pot spark erosion method. Relaxation oscillators or a pulse generator were used to power the park erosion. Commercial Neomax 35 was employed as the primary material. The dielectric media were liquid Ar, Ar gas, and hydrocarbons, which provided an oxygen free environment. Structure and size were studied by transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray diffraction. Magnetic properties were measured by vibrating sample magnetometer (VSM) with temperatures in range of 4.2-1200 K. The particles produced in these three different dielectric media had different microstructures and crystal structures. The particles made in Ar gas were pure Nd2Fe14B phase. The particles made in liquid Ar were a mixture of amorphous and crystalline Nd2Fe14B, because the liquid Ar provided a much higher quench rate than Ar gas, which produced some amorphous Nd2Fe14B. Upon annealing, the amorphous particles became crystalline. The fine particles produced in hydrocarbons, such as pentane and dodecane, had more complex mixed phases, since the rare earth reacted with the hydrocarbons during the sparking process. The phases were NdC2, alpha-Fe, and amorphous and crystalline Nd2Fe14B. The effects of power parameters, such as voltage and capacitance, on particle size were investigated. Particle sizes from 20 nm to 50 microns were obtained.

Enhancing students' critical thinking in science: A two-year design based exploration in a large undergraduate science course

NASA Astrophysics Data System (ADS)

Yoo, Suhyun

The purpose of this study was to explore how to enhance students' critical thinking in an introductory undergraduate science course. As a design experiment, this study aimed to design, develop, implement, and refine learning activities, and investigate how the learning activities worked in fostering students' critical thinking in a large size classroom context. In this study, critical thinking in science was framed with six categories, 1) identifying decisions, 2) evaluating decisions, 3) providing own decision, 4) argument and justification for own decision, 5) presenting supporting data/evidence, and 6) integrating other perspectives, as the result of literature review. To enhance critical thinking, three design principles, 1) authentic task, 2) question prompts, and 3) peer interaction, were associated with the learning activities for two consecutive years. The research context was within a large general science course and the learning activities for a module were designed, implemented and refined for two years. Specially, changes in design strategies were made in the two design principles, question prompts and peer interaction, after the 1st implementation. With regard to the use of question prompts, the students of the 2nd year were provided with procedural and elaborative question prompts, while those of the 1st year only received procedural question prompts embedded in the Group and Community Discussion Charts. Second, instead of being engaged six times in two types of discussions, group and community discussions, the students of the 2nd year were required to take part in a community discussion twice and to prepare for the discussion by learning about and understanding important aspects of dealing with the hurricane situation. For individual preparation, elaborative question prompts were embedded in the Individual Worksheet. Quantitative and qualitative research methods were taken to investigate how the two different designs of the 1st and 2nd years worked for enhancing critical thinking in a large-size classroom. Data came from the students' written documents during and after the learning activities. The result from the descriptive and comparative analysis on the written documents for two years indicated that there were changes in patterns of reasoning between the two years. It was evident that the groups engaged in decision-making for communities of the 2nd year showed more concrete and shaped reasoning than those of the 1st year. The result of the t-test indicated that there was a significant difference in critical thinking demonstrated in individual reports between the students of the 1st and the 2nd years. The students of the 2nd year demonstrated better levels of critical thinking than those of the 1st year. Specially, among the six categories of critical thinking, the students of the 2nd year demonstrated better levels in three categories, 1) providing one's own decision, 2) argumentation and justification for one's own decision, and 3) integrating other perspectives, than those of the 1st year. By the multiple-case study method, four themes were found to explain what made students demonstrated higher levels of critical thinking: 1) understanding of one's assigned role, 2) linking roles to make decisions, 3) answers to the question prompts, and 4) use of data and source, were raised in explaining the different pattern between the students with higher and lower levels of critical thinking. Also, a trend was visible across artifacts for higher performing students in both years.

Cold Multiphoton Matrix Assisted Laser Desorption/Ionization (MALDI)

NASA Astrophysics Data System (ADS)

Harris, Peter; Cooke, William; Tracy, Eugene

2008-05-01

We present evidence of a cold multiphoton MALDI process occurring at a Room Temperature Ionic Liquid (RTIL)/metal interface. Our RTIL, 1-Butyl-3-methylimidazolium hexafluorophosphate, remains a stable liquid at room temperatures, even at pressures lower than 10-9 torr. We focus the 2^nd harmonic of a pulsed (2ns pulse length) Nd:YAG laser onto a gold grid coated with RTIL to generate a cold (narrow velocity spread) ion source with temporal resolution comparable to current MALDI ion sources. Unlike conventional MALDI, we believe multiphoton MALDI does not rely on collisional ionization within the ejection plume, and thus produces large signals at laser intensities just above threshold. Removing the collisional ionization process allow us to eject material from smaller regions of a sample, enhancing the suitability of multiphoton MALDI as an ion imaging technique.

The Sm-Nd history of KREEP. [in lunar rocks

NASA Technical Reports Server (NTRS)

Lugmair, G. W.; Carlson, R. W.

1978-01-01

Sm-Nd whole rock measurements on a variety of KREEP-rich samples from different landing sites are reported. Despite a variation of Nd and Sm concentrations of almost a factor of 3, the Sm-Nd ratios, as well as the Nd-143/Nd-144 values, show an extremely close grouping. No systematic differences between samples from different landing sites are resolved. These results are taken to be indicative of a moon-wide process having been responsible for the generation of the KREEP source reservoir, 4.36 plus or minus 0.06 AE ago, as estimated from model age calculation.

Reconstruction of intermediate water circulation in the tropical North Atlantic during the past 22,000 years

NASA Astrophysics Data System (ADS)

Xie, Ruifang C.; Marcantonio, Franco; Schmidt, Matthew W.

2014-09-01

Decades of paleoceanographic studies have reconstructed a well-resolved water mass structure for the deep Atlantic Ocean during the Last Glacial Maximum (LGM). However, the variability of intermediate water circulation in the tropics over the LGM and deglacial abrupt climate events is still largely debated. This study aims to reconstruct intermediate northern- and southern-sourced water circulation in the tropical North Atlantic during the past 22 kyr and attempts to confine the boundary between Antarctic Intermediate Water (AAIW) and northern-sourced intermediate water (i.e., upper North Atlantic Deep Water (NADW) or Glacial North Atlantic Intermediate Water) in the past. High-resolution Nd isotopic compositions of fish debris and acid-reductive leachate of bulk sediment in core VM12-107 (1079 m depth) from the Southern Caribbean are not in agreement. We suggest that the leachate method does not reliably extract the Nd isotopic compositions of seawater at this location, and that it needs to be tested in more detail in various oceanic settings. The fish debris εNd values display a general decrease from the early deglaciation to the end of the Younger Dryas, followed by a greater drop toward less radiogenic values into the early Holocene. We propose a potentially more radiogenic glacial northern endmember water mass and interpret this pattern as recording a recovery of the upper NADW during the last deglaciation. Comparing our new fish debris Nd isotope data to authigenic Nd isotope studies in the Florida Straits (546 and 751 m depth), we propose that both glacial and deglacial AAIW do not penetrate beyond the lower depth limit of modern AAIW in the tropical Atlantic.

Molten salt synthesis, visible and near-IR region spectral properties of europium or neodymium doped CoNb2O6 columbite niobate.

PubMed

Ekmekçi, Mete Kaan; Erdem, Murat; Başak, Ali Sadi

2015-03-28

Pure Nd(3+)- or Eu(3+)-doped CoNb2O6 powders have been prepared by a molten salt synthesis method using a Li2SO4-Na2SO4 or NaCl-KCl salt mixture as a flux at relatively low temperatures as compared to the solid state reaction method. X-ray diffraction patterns of pure CoNb2O6 samples indicated an orthorhombic single phase. For Eu(3+)-doped CoNb2O6 samples, the luminescence of Eu(3+) was observed at 615 nm as red emission while the Nd(3+) doped sample showed a typical emission at 1064 nm varying with the Eu(3+) or Nd(3+) doping concentrations. These luminescence characteristics of the doped samples may be attributed to the energy transfer between rare earth ions and CoO6 octahedral groups in the columbite structure.

Redox properties of undoped 5 nm diamond nanoparticles.

PubMed

Holt, Katherine B; Ziegler, Christoph; Caruana, Daren J; Zang, Jianbing; Millán-Barrios, Enrique J; Hu, Jingping; Foord, John S

2008-01-14

This paper demonstrates the promoting effects of 5 nm undoped detonation diamond nanoparticles on redox reactions in solution. An enhancement in faradaic current for the redox couples Ru(NH(3))(6)(3+/2+) and Fe(CN)(6)(4-/3-) was observed for a gold electrode modified with a drop-coated layer of nanodiamond (ND), in comparison to the bare gold electrode. The ND layer was also found to promote oxygen reduction. Surface modification of the ND powders by heating in air or in a hydrogen flow resulted in oxygenated and hydrogenated forms of the ND, respectively. Oxygenated ND was found to exhibit the greatest electrochemical activity and hydrogenated ND the least. Differential pulse voltammetry of electrode-immobilised ND layers in the absence of solution redox species revealed oxidation and reduction peaks that could be attributed to direct electron transfer (ET) reactions of the ND particles themselves. It is hypothesised that ND consists of an insulating sp(3) diamond core with a surface that has significant delocalised pi character due to unsatisfied surface atoms and C[double bond, length as m-dash]O bond formation. At the nanoscale surface properties of the particles dominate over those of the bulk, allowing ET to occur between these essentially insulating particles and a redox species in solution or an underlying electrode. We speculate that reversible reduction of the ND may occur via electron injection into available surface states at well-defined reduction potentials and allow the ND particles to act as a source and sink of electrons for the promotion of solution redox reactions.

Effect of U on the electronic properties of neodymium gallate (NdGaO3): theoretical and experimental studies.

PubMed

Reshak, Ali Hussain; Piasecki, M; Auluck, S; Kityk, I V; Khenata, R; Andriyevsky, B; Cobet, C; Esser, N; Majchrowski, A; Swirkowicz, M; Diduszko, R; Szyrski, W

2009-11-19

We have performed a density functional calculation for the centrosymmetric neodymium gallate using a full-potential linear augmented plane wave method with the LDA and LDA+U exchange correlation. In particular, we explored the influence of U on the band dispersion and optical transitions. Our calculations show that U = 0.55 Ry gives the best agreement with our ellipsometry data taken in the VUV spectral range with a synchrotron source. Our LDA+U (U = 0.55) calculation shows that the valence band maximum (VBM) is located at T and the conduction band minimum (CBM) is located at the center of the Brillouin zone, resulting in a wide indirect energy band gap of about 3.8 eV in excellent agreement with our experiment. The partial density of states show that the upper valence band originates predominantly from Nd-f and O-p states, with a small admixture of Nd-s/p and Ga-p B-p states, while the lower conduction band prevailingly originates from the Nd-f and Nd-d terms with a small contribution of O-p-Ga-s/p states. The Nd-f states in the upper valence band and lower conduction band have a significant influence on the energy band gap dispersion which is illustrated by our calculations. The calculated frequency dependent optical properties show a small positive uniaxial anisotropy.

Sodium D2 resonance radiation in single-pass sum-frequency generation with actively mode-locked Nd:YAG lasers

NASA Astrophysics Data System (ADS)

Saito, Norihito; Akagawa, Kazuyuki; Ito, Mayumi; Takazawa, Akira; Hayano, Yutaka; Saito, Yoshihiko; Ito, Meguru; Takami, Hideki; Iye, Masanori; Wada, Satoshi

2007-07-01

We report on a sodium D2 resonance coherent light source achieved in single-pass sum-frequency generation in periodically poled MgO-doped stoichiometric lithium tantalate with actively mode-locked Nd:YAG lasers. Mode-locked pulses at 1064 and 1319 nm are synchronized with a time resolution of 37 ps with the phase adjustment of the radio frequencies fed to acousto-optic mode lockers. An output power of 4.6 W at 589.1586 nm is obtained, and beam quality near the diffraction limit is also achieved in a simple design.

Sodium D2 resonance radiation in single-pass sum-frequency generation with actively mode-locked Nd:YAG lasers.

PubMed

Saito, Norihito; Akagawa, Kazuyuki; Ito, Mayumi; Takazawa, Akira; Hayano, Yutaka; Saito, Yoshihiko; Ito, Meguru; Takami, Hideki; Iye, Masanori; Wada, Satoshi

2007-07-15

We report on a sodium D(2) resonance coherent light source achieved in single-pass sum-frequency generation in periodically poled MgO-doped stoichiometric lithium tantalate with actively mode-locked Nd:YAG lasers. Mode-locked pulses at 1064 and 1319 nm are synchronized with a time resolution of 37 ps with the phase adjustment of the radio frequencies fed to acousto-optic mode lockers. An output power of 4.6 W at 589.1586 nm is obtained, and beam quality near the diffraction limit is also achieved in a simple design.

Waveguide Multimode Directional Coupler for Harvesting Harmonic Power from the Output of Traveling-Wave Tube Amplifiers

NASA Technical Reports Server (NTRS)

Simons, Rainee N.; Wintucky, Edwin G.

2017-01-01

This paper presents the design, fabrication, and test results for a novel waveguide multimode directional coupler (MDC). The coupler fabricated from dissimilar frequency band waveguides, is capable of isolating power at the 2nd harmonic frequency from the fundamental power at the output port of traveling-wave tube amplifiers. Test results from proof-of-concept demonstrations are presented for Ku/Ka-band and Ka/E-band MDCs, which demonstrate sufficient power in the 2nd harmonic for a space borne beacon source for mm-wave atmospheric propagation studies.

The success and complementarity of Sm-Nd and Lu-Hf garnet geochronology

NASA Astrophysics Data System (ADS)

Baxter, E. F.; Scherer, E. E.

2013-12-01

Garnet's potential as a direct chronometer of tectonometamorphic processes and conditions was first realized over 30 years ago. Since then, the Sm-Nd and Lu-Hf systems have emerged as the most effective, with both permitting age precision < ×1 Myr. Both have proven successful not merely in dating garnet growth itself, but rather in constraining the ages, durations, and rates of particular earth processes or conditions that can be directly linked to garnet growth via chemical, thermodynamic, or petrographic, means. Appreciating important differences between Sm-Nd and Lu-Hf in terms of contaminant phases, partitioning, daughter element diffusivity, and isotopic analysis makes these two systems powerfully complementary when used and interpreted in concert. Well established, robust analytical methods mitigate the effects of ubiquitous mineral inclusions (monazite is most significant for Sm-Nd; zircon is most significant for Lu-Hf), improving the precision and accuracy of garnet dates from both systems. Parent-daughter ratios tend to be higher for Lu-Hf leading to the potential for better age precision in general. The Lu-176 decay rate is faster than Sm-147, meaning that Lu-Hf provides better age precision potential for young (Cenozoic) samples. However, Sm-Nd provides better precision potential for older (Precambrian) samples primarily because of the higher precisions on the parent-daughter ratios (i.e., 147Sm/144Nd) that can be achieved by ID-TIMS analysis. For dating microsampled zones or growth rings in single garnet crystals, Sm-Nd has proven most successful owing to more uniform distribution of Sm, and established methods to measure <10 ng quantities of Nd at high precision via TIMS. However, new MC-ICP-MS sample introduction technologies are closing this gap for small samples. For analyses of bulk garnet that grew over a protracted interval, Lu-Hf dates are expected to be older than Sm-Nd dates owing to differences in Lu and Sm zonation (i.e. Lu tends to be strongly sequestered by garnet cores, whereas Sm is more evenly distributed). Thus, Lu-Hf is often useful for targeting nucleation times (and earliest growth zones), whereas Sm-Nd is preferable when targeting the mid- to later stages (and outermost growth zones) of garnet. Depending on grain size and heating duration, most garnets can retain their primary growth chronology up to about 700 C, and thus they are one of the few metamorphic minerals that faithfully record prograde metamorphic processes and conditions. For granulite facies rocks (e.g., > about 700 C), higher retentivity (i.e., slower diffusivity) for Hf than for Nd can lead to older Lu-Hf (growth) ages compared to Sm-Nd (partially reset) dates for the same sample. Finally, as with all geochronometers, decay constant uncertainties and sources of systematic error in methods (e.g., spike calibrations) should be considered when comparing absolute Lu-Hf and Sm-Nd dates to each other or to other chronometers.

Sr and Nd isotopes of suspended sediments from rivers of the Amazon basin

NASA Astrophysics Data System (ADS)

Hatting, Karina; Santos, Roberto V.; Sondag, Francis

2014-05-01

The Rb-Sr and Sm-Nd isotopic systems are important tools to constrain the provenance of sediment load in river systems. This study presents the isotopic composition of Sr and Nd isotopes and major and minor elements in suspended sediments from the Marañón-Solimões, Amazonas and Beni-Madeira rivers. The data were used to constrain the source region of the sediments and to better understand the main seasonal and spatial transport processes within the basin based on the variations of the chemical and isotopic signals. They also allow establishing a relationship between sediment concentrations and flow rate values. The study presents data collected during a hydrological year between 2009 and 2010. The Marañón-Solimões River presents low Sr isotopic values (0.7090-0.7186), broad EpslonNd(0) range (-15.17 to -8.09) and Nd model (TDM) ages varying from 0.99 to 1.81 Ga. Sources of sediments to the Marañón-Solimões River include recent volcanic rocks in northern Peru and Ecuador, as well as rocks with long crustal residence time and carbonates from the Marañón Basin, Peru. The Beni-Madeira River has more radiogenic Sr isotope values (0.7255-0.7403), more negative EpslonNd(0) values (-20.46 to -10.47), and older Nd isotope model ages (from 1.40 to 2.35 Ga) when compared to the Marañón-Solimões River. These isotope data were related to the erosion of Paleozoic and Cenozoic foreland basins that are filled with Precambrian sediments derived from the Amazonian Craton. These basins are located in Bolivian Subandina Zone. The Amazon River presents intermediate isotopic values when compared to those found in the Marañón-Solimões and Beni-Madeira rivers. Its Sr isotope ratios range between 0.7193 and 0.7290, and its EpslonNd(0) values varies between -11.09 and -9.51. The Nd isotope model ages of the suspended sediments vary between 1.28 and 1.77 Ga. Concentrations of soluble and insoluble elements indicate a more intense weathering activity in sediments of the Beni-Madeira River. This river has a larger difference in the Sr isotopic composition between the diluted and solid phases, which has been assigned to the high level of weathering of its sediment source area. In the Beni-Madeira River sub-basin dominates weathering of silicate rocks, while in the Marañón-Solimões River sub-basin there also weathering of carbonate and evaporitic rocks.

2nd & 3rd Generation Vehicle Subsystems

NASA Technical Reports Server (NTRS)

2000-01-01

This paper contains viewgraph presentation on the "2nd & 3rd Generation Vehicle Subsystems" project. The objective behind this project is to design, develop and test advanced avionics, power systems, power control and distribution components and subsystems for insertion into a highly reliable and low-cost system for a Reusable Launch Vehicles (RLV). The project is divided into two sections: 3rd Generation Vehicle Subsystems and 2nd Generation Vehicle Subsystems. The following topics are discussed under the first section, 3rd Generation Vehicle Subsystems: supporting the NASA RLV program; high-performance guidance & control adaptation for future RLVs; Evolvable Hardware (EHW) for 3rd generation avionics description; Scaleable, Fault-tolerant Intelligent Network or X(trans)ducers (SFINIX); advance electric actuation devices and subsystem technology; hybrid power sources and regeneration technology for electric actuators; and intelligent internal thermal control. Topics discussed in the 2nd Generation Vehicle Subsystems program include: design, development and test of a robust, low-maintenance avionics with no active cooling requirements and autonomous rendezvous and docking systems; design and development of a low maintenance, high reliability, intelligent power systems (fuel cells and battery); and design of a low cost, low maintenance high horsepower actuation systems (actuators).

Radiogenic isotope evidence for transatlantic atmospheric dust transport

NASA Astrophysics Data System (ADS)

Kumar, Ashwini; Abouchami, Wafa; Garrison, Virginia H.; Galer, Stephen J. G.; Andreae, Meinrat O.

2013-04-01

Early studies by Prospero and colleagues [1] have shown that African dust reaches all across the Atlantic and into the Caribbean. It may contribute to fertilizing the Amazon rainforest [2,3,4], in addition to enhancing the ocean biological productivity via delivery of iron, a key nutrient element[5]. Radiogenic isotope ratios (Sr, Nd, Pb) are robust tracers of dust sources and can thus provide information on provenance and pathways of dust transport. Here we report Sr, Nd and Pb isotope data on atmospheric aerosols, collected in 2008 on quartz filters, from three different locations in Mali (12.6° N, 8.0° W; 555 m a.s.l.), Tobago (11.3° N, 60.5° W; 329 m a.s.l.) and the U.S. Virgin Islands (17.7° N, 64.6° W; 27 m a.s.l.) to investigate the hypothesis of dust transport across the Atlantic. About 2 cm2 of filter were acid-leached in 0.5 N HBr for selective removal of the anthropogenic labile Pb component (leachate) and possibly the fine soluble particle fraction. The remainder of the filter was subsequently dissolved using a mixture of HF and HNO3 acids, and should be representative of the silicate fraction. Isotopic compositions were measured by TIMS on a ThermoFisher Triton at MPIC, with Pb isotope ratios determined using the triple-spike method. Significant Pb isotope differences between leachates and residues were observed. The variability in Pb isotopic composition among leachates may be attributed to variable and distinct anthropogenic local Pb sources from Africa and South America [6], however, residues are imprinted by filter blank contribution suggesting to avoid the quartz fiber filter for isotopic study of aerosols. The Nd and Sr isotope ratios of aerosol leachates show similar signatures at all three locations investigated. The nearly identical Nd and Sr isotopic compositions in the Mali, Tobago and Virgin islands leachates are comparable to those obtained on samples from the Bodélé depression, Northern Chad [7] and suggest a possible common source origin. These results identify an African source signal, in aerosols from the Virgin Islands and Tobago collected during African dusts incursion, and thus provides evidence for transatlantic dust transport during the spring/summer season. This, in turn, is entirely consistent with 7-day back-trajectory analysis at these locations as well as recent seasonal AOD maps [8]. [1] Prospero et al. (1970) Earth Planet. Sci. Lett. 9, 287-293. [2] Swap et al. (1992) Tellus 44, 133-149. [3] Koren et al. (2006) Environ. Res. Lett. 1, 014005. [4] Ben-Ami et al. (2010) Atmos. Chem. Phys. 10, 7533-7544. [5] Duce & Tindale (1991) Lim Ocean., 36, 1715-1726. [6] Bollhöfer & Rosman (2000) Geochim. Cosmochim. Acta 64, 3251-3262. [7] Abouchami et al. (in prep.) [8] Ridley et al. (2012) J. Geophys. Res. 117, D02202.

Laser-stimulated desorption of organic molecules from surfaces, as a method of increasing the efficiency of ion mobility spectrometry analysis.

PubMed

Akmalov, Artem E; Chistyakov, Alexander A; Kotkovskii, Gennadii E

2017-08-01

Application of laser-induced desorption was investigated as a method of increasing the efficiency of gas phase analyzers on principles of field asymmetric ion mobility spectrometry. Mass spectrometric data of investigations of laser desorption of pentaerythritoltetranitrate molecules and cyclotetramethylenetetranitramine molecules from quartz substrate under vacuum were obtained. Laser sources a Nd 3+ :YAG with nanosecond pulse duration (λ = 532 nm) and a continuous wave diode laser (λ = 440 nm) were used. It was shown that both laser sources have different desorption abilities. This is expressed in various time of appearance of desorbed products that is caused by different heating mechanisms of surface layer. The desorbed quantity under action of both laser sources exceeds the detection threshold for all modern gas phase analyzers. It should be noted that despite the presence of surface dissociation of explosives under laser radiation, the quantity of nondissociated molecules is large enough for detection by ion mobility and field asymmetric ion mobility spectrometers. The optimal parameters of laser radiation for effective removal (evaporation) molecules of low-volatile compounds from surfaces are defined. The conclusion about preferable use of a Nd 3+ :YAG laser for increasing the detection ability of detectors based on ion mobility spectrometry was made.

Geochemical and isotopic investigation of the Laiwu-Zibo carbonatites from western Shandong Province, China, and implications for their petrogenesis and enriched mantle source

NASA Astrophysics Data System (ADS)

Ying, Jifeng; Zhou, Xinhua; Zhang, Hongfu

2004-08-01

Major and trace element and Nd-Sr isotope data of the Mesozoic Laiwu-Zibo carbonatites (LZCs) from western Shandong Province, China, provide clues to the petrogenesis and the nature of their mantle source. The Laiwu-Zibo carbonatites can be petrologically classified as calcio-, magnesio- and ferro-carbonatites. All these carbonatites show a similarity in geochemistry. On the one hand, they are extremely enriched in Ba, Sr and LREE and markedly low in K, Rb and Ti, which are similar to those global carbonatites, on the other hand, they have extremely high initial 87Sr/ 86Sr (0.7095-0.7106) and very low ɛNd (-18.2 to -14.3), a character completely different from those global carbonatites. The small variations in Sr and Nd isotopic ratios suggest that crustal contamination can not modify the primary isotopic compositions of LZC magmas and those values are representatives of their mantle source. The Nd-Sr isotopic compositions of LZCs and their similarity to those of Mesozoic Fangcheng basalts imply that they derived from an enriched lithospheric mantle. The formation of such enriched lithospheric mantle is connected with the major collision between the North China Craton (NCC) and the Yangtze Craton. Crustal materials from the Yangtze Craton were subducted beneath the NCC and melts derived from the subducted crust of the Yangtze Craton produced an enriched Mesozoic mantle, which is the source for the LZCs and Fangcheng basalts. The absence of alkaline silicate rocks, which are usually associated with carbonatites suggest that the LZCs originated from the mantle by directly partial melting.

Hadean silicate differentiation preserved by anomalous 142Nd/144Nd ratios in the Réunion hotspot source

NASA Astrophysics Data System (ADS)

Peters, Bradley J.; Carlson, Richard W.; Day, James M. D.; Horan, Mary F.

2018-03-01

Active volcanic hotspots can tap into domains in Earth’s deep interior that were formed more than two billion years ago. High-precision data on variability in tungsten isotopes have shown that some of these domains resulted from differentiation events that occurred within the first fifty million years of Earth history. However, it has not proved easy to resolve analogous variability in neodymium isotope compositions that would track regions of Earth’s interior whose composition was established by events occurring within roughly the first five hundred million years of Earth history. Here we report 142Nd/144Nd ratios for Réunion Island igneous rocks, some of which are resolvably either higher or lower than the ratios in modern upper-mantle domains. We also find that Réunion 142Nd/144Nd ratios correlate with helium-isotope ratios (3He/4He), suggesting parallel behaviour of these isotopic systems during very early silicate differentiation, perhaps as early as 4.39 billion years ago. The range of 142Nd/144Nd ratios in Réunion basalts is inconsistent with a single-stage differentiation process, and instead requires mixing of a conjugate melt and residue formed in at least one melting event during the Hadean eon, 4.56 billion to 4 billion years ago. Efficient post-Hadean mixing nearly erased the ancient, anomalous 142Nd/144Nd signatures, and produced the relatively homogeneous 143Nd/144Nd composition that is characteristic of Réunion basalts. Our results show that Réunion magmas tap into a particularly ancient, primitive source compared with other volcanic hotspots, offering insight into the formation and preservation of ancient heterogeneities in Earth’s interior.

Accretion timescale and impact history of Mars deduced from the isotopic systematics of martian meteorites

DOE PAGES

Borg, Lars E.; Brennecka, Gregory A.; Symes, Steven J. K.

2015-12-12

High precision Sm-Nd isotopic analyses have been completed on a suite of 11 martian basaltic meteorites in order to better constrain the age of silicate differentiation on Mars associated with the formation of their mantle sources. Our data is used to evaluate the merits and disadvantages of various mathematical approaches that have been employed in previous work on this topic. Ages determined from the Sm-Nd isotopic systematics of individual samples are strongly dependent on the assumed Nd isotopic composition of the bulk planet. This assumption is problematic given differences observed between the Nd isotopic composition of Earth and chondritic meteoritesmore » and the fact that these materials are both commonly used to represent bulk planetary Nd isotopic compositions. Ages determined from the slope of Sm-146-Nd-142 whole rock isochrons are not dependent on the assumed Nd-142/Nd-144 ratio of the planet, but require the sample suite to be derived from complementary, contemporaneously-formed reservoirs. In this work, we present a mathematical expression that defines the age of formation of the source regions of such a suite of samples that is based solely on the slope of a Nd-143-Nd-142 whole rock isochron and is also independent of any a priori assumptions regarding the bulk isotopic composition of the planet. This expression is also applicable to mineral isochrons and has been used to successfully calculate Nd-143-Nd-142 model crystallization ages of early refractory solids as well as lunar samples. This permits ages to be obtained using only Nd isotopic measurements without the need for Sm-147/Nd-144 isotope dilution determinations. When used in conjunction with high-precision Nd isotopic measurements completed on martian meteorites this expression yields an age of formation of the martian basaltic meteorite source regions of 4504 +/- 6 Ma. Because the Sm-Nd model ages for the formation of martian source regions are commonly interpreted to record the age at which large scale mantle reservoirs formed during planetary differentiation associated with magma ocean solidification, the age determined here implies that magma ocean solidification occurred several tens of millions of years after the beginning of the Solar System. Recent thermal models, however, suggest that Mars-sized bodies cool rapidly in less than similar to 5 Ma after accretion ceases, even in the presence of a thick atmosphere. In assuming these models are correct, an extended period of accretion is necessary to provide a mechanism to keep portions of the martian mantle partially molten until 4504 Ma. Late accretional heating of Mars could either be associated with protracted accretion occurring at a quasi-steady state or alternatively be associated with a late giant impact. If this scenario is correct, then accretion of Mars-sized bodies takes up to 60 Ma and is likely to be contemporaneous with the core formation and possibly the onset of silicate differentiation. This further challenges the concept that isotopic equilibrium is attained during primordial evolution of planets, and may help to account for geochemical evidence implying addition of material into planetary interiors after core formation was completed.« less

Accretion timescale and impact history of Mars deduced from the isotopic systematics of martian meteorites

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

Borg, Lars E.; Brennecka, Gregory A.; Symes, Steven J. K.

High precision Sm-Nd isotopic analyses have been completed on a suite of 11 martian basaltic meteorites in order to better constrain the age of silicate differentiation on Mars associated with the formation of their mantle sources. Our data is used to evaluate the merits and disadvantages of various mathematical approaches that have been employed in previous work on this topic. Ages determined from the Sm-Nd isotopic systematics of individual samples are strongly dependent on the assumed Nd isotopic composition of the bulk planet. This assumption is problematic given differences observed between the Nd isotopic composition of Earth and chondritic meteoritesmore » and the fact that these materials are both commonly used to represent bulk planetary Nd isotopic compositions. Ages determined from the slope of Sm-146-Nd-142 whole rock isochrons are not dependent on the assumed Nd-142/Nd-144 ratio of the planet, but require the sample suite to be derived from complementary, contemporaneously-formed reservoirs. In this work, we present a mathematical expression that defines the age of formation of the source regions of such a suite of samples that is based solely on the slope of a Nd-143-Nd-142 whole rock isochron and is also independent of any a priori assumptions regarding the bulk isotopic composition of the planet. This expression is also applicable to mineral isochrons and has been used to successfully calculate Nd-143-Nd-142 model crystallization ages of early refractory solids as well as lunar samples. This permits ages to be obtained using only Nd isotopic measurements without the need for Sm-147/Nd-144 isotope dilution determinations. When used in conjunction with high-precision Nd isotopic measurements completed on martian meteorites this expression yields an age of formation of the martian basaltic meteorite source regions of 4504 +/- 6 Ma. Because the Sm-Nd model ages for the formation of martian source regions are commonly interpreted to record the age at which large scale mantle reservoirs formed during planetary differentiation associated with magma ocean solidification, the age determined here implies that magma ocean solidification occurred several tens of millions of years after the beginning of the Solar System. Recent thermal models, however, suggest that Mars-sized bodies cool rapidly in less than similar to 5 Ma after accretion ceases, even in the presence of a thick atmosphere. In assuming these models are correct, an extended period of accretion is necessary to provide a mechanism to keep portions of the martian mantle partially molten until 4504 Ma. Late accretional heating of Mars could either be associated with protracted accretion occurring at a quasi-steady state or alternatively be associated with a late giant impact. If this scenario is correct, then accretion of Mars-sized bodies takes up to 60 Ma and is likely to be contemporaneous with the core formation and possibly the onset of silicate differentiation. This further challenges the concept that isotopic equilibrium is attained during primordial evolution of planets, and may help to account for geochemical evidence implying addition of material into planetary interiors after core formation was completed.« less

Structure, spectroscopic properties and laser performance of Nd:YNbO4 at 1066 nm

NASA Astrophysics Data System (ADS)

Ding, Shoujun; Peng, Fang; Zhang, Qingli; Luo, Jianqiao; Liu, Wenpeng; Sun, Dunlu; Dou, Renqin; Sun, Guihua

2016-12-01

We have demonstrated continuous wave (CW) laser operation of Nd:YNbO4 crystal at 1066 nm for the first time. A maximum output power of 1.12 W with the incident power of 5.0 W is successfully achieved corresponding to an optical-to-optical conversion efficiency of 22.4% and a slope efficiency of 24.0%. The large absorption cross section (8.7 × 10-20 cm2) and wide absorption band (6 nm) at around 808 nm indicates the good pumping efficiency by laser diodes (LD). The small emission cross section (29 × 10-20 cm2) and relative long lifetime of the 4F3/2 → 4I11/2 transition indicates good energy storage capacity of Nd:YNbO4. Moreover, the raw materials of Nd:YNbO4 are stable, thus, it can grow high-quality and large-size by Czochralski (CZ) method. Therefore the Nd:YNbO4 crystal is a potentially new laser material suitable for LD pumping.

Chromium Isotopes in Carbonates - a Tracer for Climate Change and for Reconstructing the Redox state of Ancient Seawater

NASA Astrophysics Data System (ADS)

Frei, R.; Gaucher, C.; Dossing, L. N.; Sial, A. N.

2011-12-01

Strontium and carbon isotopes of marine carbonates are routinely applied for chemostratigraphic cross correlations of time-equivalent sedimentary sequences and for calibration of the compositional evolution of seawater throughout Earth's history, mainly for the purpose of reconstructing ancient climatic changes. We here present results of a new isotopic tracer system - stable chromium isotopes - applied to a late Ediacaran (Vendian) marine carbonate sequence exposed in the Calera de Recalde syncline, Arroyo del Soldado Group, Uruguay. The aim was to compare Cr isotope signatures directly to δ13C, 87Sr/86Sr and 143Nd/144Nd fluctuations in a well defined stratigraphic profile comprising sediments that were deposited during cold-warm periods accompanied by sea-level changes in response to glaciation-deglaciation at higher latitudes. The studied section is characterized by a pronounced negative (down to -3.3%) δ13C excursion in carbonates paralleled by a decrease of 87Sr/86Sr values. Chromium isotope signatures over this section also show a correlated decrease in δ53Cr (δ53Cr = [(53Cr/52Cr)sample/(53Cr/52Cr)SRM979)-1] x 1000) values from ~+0.29to -0.17% which mirrors a decrease in positively fractioned seawater signatures to slightly negative values characteristic of high-temperature magmatic sources. Linear correlations between δ53Cr and ɛNd(T=570 Ma), 87Sr/86Sr and Cr concentrations can be explained by mixing between two major input sources of Cr, Nd and Sr into the shallow seawater: 1) a source characterized by negative δ53Cr values of ~-0.2% , low 87Sr/86Sr values of ~0.707, and elevated 147Sm/144Nd values of ~0.13, recognized as a subaqueous hydrothermal dominated input source, and 2) a source characterized by positively fractionated δ53Cr values of ~+0.2%, higher 87Sr/86Sr values of ~0.708, and lower 147Sm/144Nd values of ~0.11, a source which is strongly affected by continentally derived input. Chromium isotopes provide a powerful tool for reconstructing the redox state of ancient seawater since positive values indicate that, at least locally, Neoproterozoic shallow ocean waters were sufficiently oxidized to fractionate chromium and/or that oxygen levels of the atmosphere were sufficient to transform Cr(III) into the more mobile hexavalent Cr(VI) formed during weathering processes on land. The fact that 87Sr/86Sr values, despite δ13C fluctuations, remain low (indicative of a strong hydrothermal input into the basin at his time) implies that CO2 limitation was the cause of negative δ13C and δ53Cr excursions in otherwise nutrient rich late Vendian basins, and that glaciation is only one more consequence of a tectonically driven, biologically mediated system. In such a scenario, glaciation acts as an amplifier of δ53Cr signals. These signals in marine carbonates are a sensitive tracer for redox processes in the ocean and/or on land and have the potential to contribute significantly to the reconstruction of climatic changes, particularly those that are associated with major glaciation periods in Earth's history.

Geochemical and multi-isotopic ( 87Sr/ 86Sr, 143Nd/ 144Nd, 238U/ 235U) perspectives of sediment sources, depositional conditions, and diagenesis of the Marcellus Shale, Appalachian Basin, USA

DOE PAGES

Phan, Thai T.; Gardiner, James B.; Capo, Rosemary C.; ...

2017-10-25

Here, we investigate sediment sources, depositional conditions and diagenetic processes affecting the Middle Devonian Marcellus Shale in the Appalachian Basin, eastern USA, a major target of natural gas exploration. Multiple proxies, including trace metal contents, rare earth elements (REE), the Sm-Nd and Rb-Sr isotope systems, and U isotopes were applied to whole rock digestions and sequentially extracted fractions of the Marcellus shale and adjacent units from two locations in the Appalachian Basin. The narrow range of εNd values (from –7.8 to –6.4 at 390 Ma) is consistent with derivation of the clastic sedimentary component of the Marcellus Shale from amore » well-mixed source of fluvial and eolian material of the Grenville orogenic belt, and indicate minimal post-depositional alteration of the Sm-Nd system. While silicate minerals host >80% of the REE in the shale, data from sequentially extracted fractions reflect post-depositional modifications at the mineralogical scale, which is not observed in whole rock REE patterns.« less

Geochemical and multi-isotopic ( 87Sr/ 86Sr, 143Nd/ 144Nd, 238U/ 235U) perspectives of sediment sources, depositional conditions, and diagenesis of the Marcellus Shale, Appalachian Basin, USA

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

Phan, Thai T.; Gardiner, James B.; Capo, Rosemary C.

Here, we investigate sediment sources, depositional conditions and diagenetic processes affecting the Middle Devonian Marcellus Shale in the Appalachian Basin, eastern USA, a major target of natural gas exploration. Multiple proxies, including trace metal contents, rare earth elements (REE), the Sm-Nd and Rb-Sr isotope systems, and U isotopes were applied to whole rock digestions and sequentially extracted fractions of the Marcellus shale and adjacent units from two locations in the Appalachian Basin. The narrow range of εNd values (from –7.8 to –6.4 at 390 Ma) is consistent with derivation of the clastic sedimentary component of the Marcellus Shale from amore » well-mixed source of fluvial and eolian material of the Grenville orogenic belt, and indicate minimal post-depositional alteration of the Sm-Nd system. While silicate minerals host >80% of the REE in the shale, data from sequentially extracted fractions reflect post-depositional modifications at the mineralogical scale, which is not observed in whole rock REE patterns.« less

Deglacial dust provenance changes in the Eastern Equatorial Pacific and implications for ITCZ movement

NASA Astrophysics Data System (ADS)

Xie, Ruifang C.; Marcantonio, Franco

2012-02-01

The provenance of eolian dust supplied to deep-sea sediments has the potential to offer insights into changes in past atmospheric circulation. Specifically, measuring temporal changes in dust provenance can shed light on changes in the mean position of the Intertropical Convergence Zone (ITCZ), a region acting as a barrier separating wind-blown material derived from northern versus southern hemisphere sources. Here we have analyzed Nd, Sr, and Pb isotope ratios in the operationally-defined detrital component extracted from deep-sea sediments in the eastern equatorial Pacific (EEP) along a meridional transect at 110°W from 3°S to 7°N (ODP Leg 138, sites 848-853). Sr isotope results show that barite Sr has a significant influence on 87Sr/86Sr isotope ratios of samples in the upwelling zone of the EEP. However, sites located >3° or more away from the equator (sites 852 and 853) are believed to not be affected by barite Sr and provide useful detrital Sr signals. 208Pb/206Pb and 207Pb/206Pb ratios in all cores fall into the Pb-isotope space of five potential dust sources (Asia, North and Central/South America, Sahara, and Australia), with no distinct isotopic fingerprinting of the dominant source(s). ɛNd values were most valuable for discerning detrital source provenance, and their values at all sites, ranging from -5.46 to -3.25, were more unradiogenic for sediments deposited during the last glacial than for those deposited during the Holocene. There are distinct latitudinal trends in the ɛNd values, with more radiogenic values further south and less radiogenic values further north, excluding site 848. This distinction holds true for both Holocene and last glacial periods. For the most southerly site, 848, we invoke, for the first time, a distinct southern hemisphere Australian source as being responsible for the unradiogenic Nd isotope ratios. Both average last glacial and Holocene ɛNd values show similar sharp gradients along the transect between 5.29°N and 2.77°N, suggesting little movement of the glacial ITCZ in the EEP. However, during the deglacial, this gradient is stronger and shifted further north between 5.29°N and 7.21°N, suggesting a more northerly, possibly stronger, deglacial ITCZ.

Northwest Africa 8159: An approximately 2.3 Billion Year Old Martian Olivine-Bearing Augite Basalt

NASA Technical Reports Server (NTRS)

Simon, J. I.; Peters, T. J.; Tappa, M. J.; Agee, C. B.

2014-01-01

Based on petrology, mineralogy, and bulk composition, the new NWA 8159 martian meteorite is distinct from all known samples from Mars. In particular, the augite compositional trends are unique, but most similar to those of nakhite intercumulus. Whether NWA 8159 represents a new lithology or is related to a known meteorite group remains to be determined. Sr and Nd isotopic analyses will allow comparison of source characteristics with SNC and other new ungrouped meteorites (e.g., NWA 7635). Here we report initial Rb-Sr and Sm-Nd isotopic results for NWA 8159 with the objective to determine its formation age and to potentially identify similarities and potential source affinities with other martian rocks.

Spatial distribution, source apportionment and ecological risk assessment of residual organochlorine pesticides (OCPs) in the Himalayas.

PubMed

Devi, Ningombam Linthoingambi; Yadav, Ishwar Chandra; Raha, Priyankar; Shihua, Qi; Dan, Yang

2015-12-01

The Indian Himalayan Region (IHR) is one of the important mountain ecosystems among the global mountain system which support wide variety of flora, fauna, human communities and cultural diversities. Surface soil samples collected from IHR were analysed for 23 organochlorine pesticides (OCPs). The concentration of ∑OCPs ranged from 0.28 to 2143.96 ng/g (mean 221.54 ng/g) and was mostly dominated by DDTs. The concentration of ∑DDTs ranged from 0.28 to 2126.94 ng/g (mean 216.65 ng/g). Other OCPs such as HCHs, endosulfan and heptachlor, Aldrin and dieldrin were detected in lower concentration in IHR. Their concentrations in soil samples ranged from ND to 2.79 ng/g for HCHs, ND to 2.83 ng/g for endosulfans, NDto 1.46 ng/g for heptachlor, ND to 2.12 ng/g for Aldrin and ND to 1.81 ng/g for dieldrin. Spatial distribution of OCPs suggested prevalence of DDTs and HCHs at Guwahati and Itanagar, respectively. The close relationship between total organic carbon (TOC) and part of OCP compounds (especially α- and γ-HCH) indicated the important role of TOC in accumulation, binding and persistence of OCP in soil. Diagnostic ratio of DDT metabolites and HCH isomers showed DDT contamination is due to recent application of technical DDT and dicofol, and HCH contamination was due to mixture of technical HCH and lindane source. This was further confirmed by principal component analysis. Ecological risk analysis of OCP residues in soil samples concluded the moderate to severe contamination of soil.

Analogical Transfer by Spanish-English Bilinguals: Implications for Educational and Employment Settings

ERIC Educational Resources Information Center

Fukumine, Eri; Kennison, Shelia M.

2016-01-01

The present research investigated analogical transfer during problem solving by bilinguals. In a study with 50 Spanish-English bilinguals, participants solved a target problem whose solution was similar to that of a preceding source problem. The source problem was always presented in the 2nd language; the target problem was always presented in the…

Origin of increased terrigenous supply to the NE South American continental margin during Heinrich Stadial 1 and the Younger Dryas

NASA Astrophysics Data System (ADS)

Zhang, Yancheng; Chiessi, Cristiano M.; Mulitza, Stefan; Zabel, Matthias; Trindade, Ricardo I. F.; Hollanda, Maria Helena B. M.; Dantas, Elton L.; Govin, Aline; Tiedemann, Ralf; Wefer, Gerold

2015-12-01

We investigate the redistribution of terrigenous materials in the northeastern (NE) South American continental margin during slowdown events of the Atlantic Meridional Overturning Circulation (AMOC). The compilation of stratigraphic data from 108 marine sediment cores collected across the western tropical Atlantic shows an extreme rise in sedimentation rates off the Parnaíba River mouth (about 2°S) during Heinrich Stadial 1 (HS1, 18-15 ka). Sediment core GeoB16206-1, raised offshore the Parnaíba River mouth, documents relatively constant 143Nd/144Nd values (expressed as εNd(0)) throughout the last 30 ka. Whereas the homogeneous εNd(0) data support the input of fluvial sediments by the Parnaíba River from the same source area directly onshore, the increases in Fe/Ca, Al/Si and Rb/Sr during HS1 indicate a marked intensification of fluvial erosion in the Parnaíba River drainage basin. In contrast, the εNd(0) values from sediment core GeoB16224-1 collected off French Guiana (about 7°N) suggest Amazon-sourced materials within the last 30 ka. We attribute the extremely high volume of terrigenous sediments deposited offshore the Parnaíba River mouth during HS1 to (i) an enhanced precipitation in the catchment region and (ii) a reduced North Brazil Current, which are both associated with a weakened AMOC.

Strategic coating of NdFeB magnets with Dy to improve the coercivity of permanent magnets

DOE PAGES

Ucar, Huseyin; Parker, David S.; Nlebedim, I. C.; ...

2015-12-25

Here, we present a method, supported by theoretical analysis, for optimizing the usage of the critical rare earth element dysprosium in Nd 2Fe 14B (NdFeB)-based permanent magnets. In this method, we use Dy selectively in locations such as magnet edges and faces, where demagnetization factors are most significant, rather than uniformly throughout the bulk sample. A 200 nm thick Dy film was sputtered onto commercial N-38, NdFeB magnets with a thickness of 3 mm and post-annealed at temperatures from 600 - 700 C. Magnets displayed enhanced coercivities after post-annealing. Furthermore, our experimental results indicate as large as a 5 percentmore » increase in the energy product of NdFeB magnets, achieved for a total Dy weight percentage of 0.06 percent, much less than that used in commercial grade Dy-NdFeB magnets. Finally, by assuming all Dy diffused into NdFeB magnets, the improvement in energy product corresponds to a saving of over 1% Dy (critical element). Magnets manufactured using this technique will therefore be higher performing and significantly less expensive than those made presently.« less

Production of cold beams of ND{sub 3} with variable rotational state distributions by electrostatic extraction of He and Ne buffer-gas-cooled beams

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

Twyman, Kathryn S.; Bell, Martin T.; Heazlewood, Brianna R.

2014-07-14

The measurement of the rotational state distribution of a velocity-selected, buffer-gas-cooled beam of ND{sub 3} is described. In an apparatus recently constructed to study cold ion-molecule collisions, the ND{sub 3} beam is extracted from a cryogenically cooled buffer-gas cell using a 2.15 m long electrostatic quadrupole guide with three 90° bends. (2+1) resonance enhanced multiphoton ionization spectra of molecules exiting the guide show that beams of ND{sub 3} can be produced with rotational state populations corresponding to approximately T{sub rot} = 9–18 K, achieved through manipulation of the temperature of the buffer-gas cell (operated at 6 K or 17 K),more » the identity of the buffer gas (He or Ne), or the relative densities of the buffer gas and ND{sub 3}. The translational temperature of the guided ND{sub 3} is found to be similar in a 6 K helium and 17 K neon buffer-gas cell (peak kinetic energies of 6.92(0.13) K and 5.90(0.01) K, respectively). The characterization of this cold-molecule source provides an opportunity for the first experimental investigations into the rotational dependence of reaction cross sections in low temperature collisions.« less

Subduction-modified oceanic crust in the sources of continental picrite dikes from the Karoo LIP?

NASA Astrophysics Data System (ADS)

Heinonen, J. S.; Carlson, R. W.; Riley, T. R.; Luttinen, A. V.; Horan, M. F.

2013-12-01

The Ahlmannryggen mountain range in East Antarctica hosts unusual LILE-depleted, but Fe- and Ti-enriched ultramafic dikes (Group 3) that belong to the Jurassic (~180 Ma) Karoo continental flood basalt (CFB) province. Their high initial ɛNd (+5 to +9) indicates their origin within the sublithospheric mantle beneath the Gondwana supercontinent. Using the new Pb and Os isotopic data and previously published geochemical and mineral chemical data, we try to constrain their mantle sources. The dikes that lack evidence of crustal contamination exhibit very radiogenic ɛNd (+8.6 to +9.0), relatively radiogenic 206Pb/204Pb (18.2-18.4) and 87Sr/86Sr (0.7035-0.7037), and unradiogenic 187Os/188Os (0.124-0.125) at 180 Ma. These isotopic compositions are unlike those typical of MORBs, excluding depleted mantle as the sole source contributor. The Pb isotopic composition of the dikes plots close to the 4.43 Ga geochron and hence is compatible with derivation from an early-depleted reservoir (EDR), recently suggested to be a major source component in CFBs. However, the high ɛNd of the dikes exceeds the ɛNd estimated for EDR (+4.9 to +8.5 at 180 Ma) and the relative Nb, Fe, and Ti enrichment (pyroxenite fingerprint) of the dikes is not readily ascribed to EDR source. Based on our isotopic and trace element modeling, we regard that the mantle source of the picrite dikes contained seawater-altered and subduction-modified MORB with a recycling age of 0.8 Ga. Such a source component would explain the unusual combination of elevated initial 87Sr/86Sr, ɛNd, and 206Pb/204Pb, relative depletion in fluid-mobile LILE, U, Th, Pb, and LREE, and relative enrichment in Nb, Fe, Ti, and other HFSE. Behavior of Re and Os in subduction environments is not well constrained, but loss of Re from recycled MORB, as observed in some subduction-associated eclogites and blueschists, and predominant contribution of Os from depleted peridotite matrix could have produced the observed low 187Os/188Os. Pyroxenite sources also are consistent with mineral chemical data (e.g., high-Ni olivine) for the picrite dikes. Such peculiar sources were likely not a predominant component in Karoo magmatism in general. Nevertheless, less subduction-modified or more enriched (e.g., additional sediment component) recycled crustal signatures would be difficult to distinguish from the 'lithospheric signatures' of many common CFBs. In addition to depleted mantle or EDR components that have been identified in the high-Mg dikes of the adjacent Vestfjella mountain range, a variety of recycled source components could thus be hiding in the geochemical jungle of the Karoo (and other) CFBs.

Sr and Nd isotope composition of the metamorphic, sedimentary and ultramafic xenoliths of Lanzarote (Canary Islands): Implications for magma sources

NASA Astrophysics Data System (ADS)

Aparicio, Alfredo; Tassinari, Colombo C. G.; García, Roberto; Araña, Vicente

2010-01-01

The lavas produced by the Timanfaya eruption of 1730-1736 (Lanzarote, Canary Islands) contain a great many sedimentary and metamorphic (metasedimentary), and mafic and ultramafic plutonic xenoliths. Among the metamorphosed carbonate rocks (calc-silicate rocks [CSRs]) are monomineral rocks with forsterite or wollastonite, as well as rocks containing olivine ± orthopyroxene ± clinopyroxene ± plagioclase; their mineralogical compositions are identical to those of the mafic (gabbros) and ultramafic (dunite, wherlite and lherzolite) xenoliths. The 87Sr/ 86Sr (around 0.703) and 143Nd/ 144Nd (around 0.512) isotope ratios of the ultramafic and metasedimentary xenoliths are similar, while the 147Sm/ 144Nd ratios show crustal values (0.13-0.16) in the ultramafic xenoliths and mantle values (0.18-0.25) in some CSRs. The apparent isotopic anomaly of the metamorphic xenoliths can be explained in terms of the heat source (basaltic intrusion) inducing strong isotopic exchange ( 87Sr/ 86Sr and 143Nd/ 144Nd) between metasedimentary and basaltic rocks. Petrofabric analysis also showed a possible relationship between the ultramafic and metamorphic xenoliths.

Natural aerosols explain seasonal and spatial patterns of Southern Ocean cloud albedo

PubMed Central

McCoy, Daniel T.; Burrows, Susannah M.; Wood, Robert; Grosvenor, Daniel P.; Elliott, Scott M.; Ma, Po-Lun; Rasch, Phillip J.; Hartmann, Dennis L.

2015-01-01

Atmospheric aerosols, suspended solid and liquid particles, act as nucleation sites for cloud drop formation, affecting clouds and cloud properties—ultimately influencing the cloud dynamics, lifetime, water path, and areal extent that determine the reflectivity (albedo) of clouds. The concentration Nd of droplets in clouds that influences planetary albedo is sensitive to the availability of aerosol particles on which the droplets form. Natural aerosol concentrations affect not only cloud properties themselves but also modulate the sensitivity of clouds to changes in anthropogenic aerosols. It is shown that modeled natural aerosols, principally marine biogenic primary and secondary aerosol sources, explain more than half of the spatiotemporal variability in satellite-observed Nd. Enhanced Nd is spatially correlated with regions of high chlorophyll a, and the spatiotemporal variability in Nd is found to be driven primarily by high concentrations of sulfate aerosol at lower Southern Ocean latitudes (35o to 45oS) and by organic matter in sea spray aerosol at higher latitudes (45o to 55oS). Biogenic sources are estimated to increase the summertime mean reflected solar radiation in excess of 10 W m–2 over parts of the Southern Ocean, which is comparable to the annual mean increases expected from anthropogenic aerosols over heavily polluted regions of the Northern Hemisphere. PMID:26601216

Constraining Mantle Differentiation Processes with La-Ce and Sm-Nd Isotope Systematics

NASA Astrophysics Data System (ADS)

Willig, M.; Stracke, A.

2016-12-01

Cerium (Ce) and Neodymium (Nd) isotopic ratios in oceanic basalts reflect the time integrated La-Ce and Sm-Nd ratios, and hence the extent of light rare earth element element (LREE) depletion or enrichment of their mantle sources. New high precision Ce-Nd isotope data from several ocean islands define a tight array in ԑCe-ԑNd space with ԑNd = -8.2±0.4 ԑCe + 1.3±0.9 (S.D.), in good agreement with previous data [1, 2]. The slope of the ԑCe-ԑNd array and the overall isotopic range are sensitive indicators of the processes that govern the evolution of the mantle's LREE composition. A Monte Carlo approach is employed to simulate continuous mantle-crust differentiation by partial melting and recycling of crustal materials. Partial melting of mantle peridotites produces variably depleted mantle and oceanic crust, which evolve for different time periods, before the oceanic crust is recycled back into the mantle including small amounts of continental crust (GLOSS [3]). Subsequently, depleted mantle and recycled materials of variable age and composition melt, and the respective melts mix in different proportions. Mixing lines strongly curve towards depleted mantle, and tend to be offset from the data for increasingly older and more depleted mantle. Observed ԑCe-ԑNd in ridge [1] and ocean island basalts and the slope of the ԑCe-ԑNd array therefore define upper limits for the extent and age of LREE depletion preserved in mantle peridotites. Very old average mantle depletion ages (> ca. 1-2 Ga) for the bulk of the mantle are difficult to reconcile with the existing ԑCe-ԑNd data, consistent with the range of Nd-Hf-Os model ages in abyssal peridotites [4-6]. Moreover, unless small amounts of continental crust are included in the recycled material, it is difficult to reproduce the relatively shallow slope of the ԑCe-ԑNd array, consistent with constraints from the ԑNd - ԑHf mantle array [7]. [1] Makishima and Masuda, 1994 Chem. Geol. 118, 1-8. [2] Doucelance et al., 2014 EPSL 407, 175-186. [3] Plank, 2014 ToG, 607-629. [4] Stracke et al., 2011 EPSL 308, 359-368. [5] Mallick et al., 2014 G-cubed 15, 2438-2453. [6] Harvey et al., 2006 EPSL 244, 606-621. [7] Chauvel et al. 2008. Nat. Geosci. 1, 64 - 67.

An Operationally Simple Method for Separating the Rare-Earth Elements Neodymium and Dysprosium.

PubMed

Bogart, Justin A; Lippincott, Connor A; Carroll, Patrick J; Schelter, Eric J

2015-07-06

Rare-earth metals are critical components of electronic materials and permanent magnets. Recycling of consumer materials is a promising new source of rare earths. To incentivize recycling there is a clear need for simple methods for targeted separations of mixtures of rare-earth metal salts. Metal complexes of a tripodal nitroxide ligand [{(2-(t) BuNO)C6 H4 CH2 }3 N](3-) (TriNOx(3-) ), feature a size-sensitive aperture formed of its three η(2) -(N,O) ligand arms. Exposure of metal cations in the aperture induces a self-associative equilibrium comprising [M(TriNOx)thf]/ [M(TriNOx)]2 (M=rare-earth metal). Differences in the equilibrium constants (Keq ) for early and late metals enables simple Nd/Dy separations through leaching with a separation ratio SNd/Dy =359. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Diode-pumped passively Q-switched Nd:GdTaO4 laser based on tungsten disulfide nanosheets saturable absorber at 1066 nm

NASA Astrophysics Data System (ADS)

Li, M. X.; Jin, G. Y.; Li, Y.

2018-05-01

In this paper, we investigated the passively Q-switched Nd:GdTaO4 laser based on tungsten disulfide (WS2) saturable absorber (SA). The preparation method of WS2 SA was to attach the WS2-alcohol dispersion onto the quartz substrates. The diode-pumped passively Q-switched Nd:GdTaO4 laser operated at a central wavelength of 1066 nm. The stable pulse output could be obtained at the single pulse width of 560 ns. In a word, WS2 seems to be a suitable saturable absorber for solid state lasers.

Mantle transition zone input to kimberlite magmatism near a subduction zone: Origin of anomalous Nd-Hf isotope systematics at Lac de Gras, Canada

NASA Astrophysics Data System (ADS)

Tappe, Sebastian; Graham Pearson, D.; Kjarsgaard, Bruce A.; Nowell, Geoff; Dowall, David

2013-06-01

Late Cretaceous-Eocene kimberlites from the Lac de Gras area, central Slave craton, show the most extreme Nd-Hf isotope decoupling observed for kimberlites worldwide. They are characterized by a narrow range of moderately enriched Nd isotope compositions (ɛNd(i)=-0.4 to -3.5) that contrasts strongly with their moderately depleted to highly enriched ɛHf(i) values (+3.9 to -9.9). Although digestion of cratonic mantle material in proto-kimberlite melt can theoretically produce steep arrays in Nd-Hf isotope space, the amount of contaminant required to explain the Lac de Gras data is unrealistic. Instead, it is more plausible that mixing of compositionally discrete melt components within an isotopically variable source region is responsible for the steep Nd-Hf isotope array. As development of strongly negative ΔɛHf requires isotopic aging of a precursor material with Sm/Nd≫Lu/Hf for billion-year timescales, a number of models have been proposed where ancient MORB crust trapped in the mantle transition zone is the ultimate source of the extreme Hf isotope signature. However, we provide a conceptual modification and demonstrate that OIB-type domains within ancient subducted oceanic lithosphere can produce much stronger negative ΔɛHf during long-term isolation. Provided that these OIB-type domains have lower melting points compared with associated MORB crust, they are among the first material to melt within the transition zone during thermal perturbations. The resulting hydrous alkali silicate melts react strongly with depleted peridotite at the top of the transition zone and transfer negative ΔɛHf signatures to less dense materials, which can be more easily entrained within upward flowing mantle. Once these entrained refertilized domains rise above 300 km depth, they may become involved in CO2- and H2O-fluxed redox melting of upper mantle peridotite beneath a thick cratonic lid. We argue that incorporation of ancient transition zone material, which includes ultradeep diamonds, into the convecting upper mantle source region of Lac de Gras kimberlites was due to vigorous mantle return flow. This occurred in direct response to fast and complex subduction along the western margin of North America during the Late Cretaceous.

46 CFR 59.01-2 - Incorporation by reference.

Code of Federal Regulations, 2011 CFR

2011-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING REPAIRS TO BOILERS... Engineering Standards (CG-521), 2100 2nd St., SW., Stop 7126, Washington, DC 20593-7126, and is available from the sources listed below. (b) American Society of Mechanical Engineers (ASME) International, Three...

46 CFR 59.01-2 - Incorporation by reference.

Code of Federal Regulations, 2012 CFR

2012-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING REPAIRS TO BOILERS... Engineering Standards (CG-ENG), 2100 2nd St., SW., Stop 7126, Washington, DC 20593-7126, and is available from the sources listed below. (b) American Society of Mechanical Engineers (ASME) International, Three...

46 CFR 59.01-2 - Incorporation by reference.

Code of Federal Regulations, 2010 CFR

2010-10-01

... Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING REPAIRS TO BOILERS... Engineering Standards (CG-521), 2100 2nd St., SW., Stop 7126, Washington, DC 20593-7126, and is available from the sources listed below. (b) American Society of Mechanical Engineers (ASME) International, Three...

Evaluation damage threshold of optical thin-film using an amplified spontaneous emission source

NASA Astrophysics Data System (ADS)

Zhou, Qiong; Sun, Mingying; Zhang, Zhixiang; Yao, Yudong; Peng, Yujie; Liu, Dean; Zhu, Jianqiang

2014-10-01

An accurate evaluation method with an amplified spontaneous emission (ASE) as the irradiation source has been developed for testing thin-film damage threshold. The partial coherence of the ASE source results in a very smooth beam profile in the near-field and a uniform intensity distribution of the focal spot in the far-field. ASE is generated by an Nd: glass rod amplifier in SG-II high power laser facility, with pulse duration of 9 ns and spectral width (FWHM) of 1 nm. The damage threshold of the TiO2 high reflection film is 14.4J/cm2 using ASE as the irradiation source, about twice of 7.4 J/cm2 that tested by a laser source with the same pulse duration and central wavelength. The damage area induced by ASE is small with small-scale desquamation and a few pits, corresponding to the defect distribution of samples. Large area desquamation is observed in the area damaged by laser, as the main reason that the non-uniformity of the laser light. The ASE damage threshold leads to more accurate evaluations of the samples damage probability by reducing the influence of hot spots in the irradiation beam. Furthermore, the ASE source has a great potential in the detection of the defect distribution of the optical elements.

Significant reduction of saturation magnetization and microwave-reflection loss in barium-natural ferrite via Nd3+ substitution

NASA Astrophysics Data System (ADS)

Widanarto, W.; Ardenti, E.; Ghoshal, S. K.; Kurniawan, C.; Effendi, M.; Cahyanto, W. T.

2018-06-01

To minimize the signal degradation, many electronic devices require efficient microwave absorbers with very low reflection-losses within the X-band. We prepared a series of trivalent neodymium-ion (Nd3+) substituted barium-natural ferrite using a modified solid-state reaction method. The effect of the Nd3+-ion content on the structure, surface morphology, magnetic properties, and microwave reflection loss was studied. The composites were characterized using X-ray diffraction, a vibrating sample magnetometer, scanning electron microscopy, and a vector network analyzer. The XRD patterns of the sample without Nd3+ reveal the presence of BaFe12O19 (hexagonal) and BaFe2O4 (rhombohedral) phases. Furthermore, a new hexagonal crystal phase of Ba6Nd2Fe4O15 appeared after substituting Nd3+. The average size of the prepared barium-natural ferrite particles was estimated to be between 0.4 and 0.8 μm. Both saturation magnetization and microwave reflection losses of these barium-ferrites were significantly reduced by increasing the Nd3+ content.

Determination of organophosphate diesters in urine samples by a high-sensitivity method based on ultra high pressure liquid chromatography-triple quadrupole-mass spectrometry.

PubMed

Su, Guanyong; Letcher, Robert J; Yu, Hongxia

2015-12-24

Organophosphate (OP) diesters in urine samples have potential use as biomarkers of organism exposure to environmentally relevant OP triester precursors and in particular OP triester flame retardants. This present study developed a quantitatively sensitive ultra high pressure liquid chromatography (UHPLC-MS) based method for urine and the determination of OP diesters (i.e. diphenyl phosphate (DPHP), bis(2-chloroethyl) phosphate (BCEP), bis(2-chloroisopropyl) phosphate (BDCIPP), di-n-butyl phosphate (DNBP), di(2-ethylhexyl) phosphate (DEHP), bis(1-chloro-2-propyl) phosphate (BCIPP), and bis(2-butoxyethyl) phosphate (BBOEP)). Fortified with the 7 OP diesters, 1mL of human urine sample was cleaned up using weak anion exchange solid phase extraction and eluted with high ionic strength ammonium acetate buffer. Subsequently, 4 non-chlorinated OP diesters were directly determined using UHPLC-electrospray(-)-triple quadrupole-MS (UHPLC-ESI(-)-QqQ-MS), and UHPLC-ESI(+)-QqQ-MS was used for determination of 3 chlorinated OP diesters after methylation using diazomethane. Recovery efficiencies of OP diesters ranged from 88 to 160% at three spiking levels (0.4, 2 and 10ng/mL urine). Matrix effects (MEs) and method limits of quantification (MLOQs) were 15-134% and 0.10-0.32ng/mL urine, respectively. Concentrations of OP diesters in n=12 urine samples (from 4 Canadian residents, 2014) varied as follows, nd-<0.28 (DNBP), nd-1.29 (DPHP), nd-<0.28 (DEHP), <0.16-12.33 (BCEP), nd-1.17 (BCDIPP) and nd-0.68ng/mL (BCIPP). Copyright © 2015. Published by Elsevier B.V.

Optically Controlled Devices and Ultrafast Laser Sources for Signal Processing.

DTIC Science & Technology

1987-06-30

A2 are input/output cavity coupling elements. C1 and C2 are coaxial cables. The resistance (R) and inductance L) provide isolation between the DC power ...the same power . 3. The continuously operating phosphate Nd:glass laser has been modelocked for the first time ever to generate 7 ps pulses. We have...media in a modelocked laser to understand the fundamental pulse generation mechanism. 2. Develop compact, high- power sources of short pulses using

Reconciling the shadow of a subduction signature with rift geochemistry and tectonic environment in Eastern Marie Byrd Land, Antarctica

NASA Astrophysics Data System (ADS)

LeMasurier, Wesley E.; Choi, Sung Hi; Hart, Stanley R.; Mukasa, Sam; Rogers, Nick

2016-09-01

Basalt-trachyte volcanoes in the Marie Byrd Land (MBL) Cenozoic province lie along the Amundsen Sea coast on the north flank of the West Antarctic rift. Basalts here are characterized by OIB-like geochemistry, restricted ranges of 87Sr/86Sr (0.702535-0.703284) and 143Nd/144Nd (0.512839-0.513008) and a wide range of 206Pb/204Pb (19.357-20.934). Basalts at three MBL volcanoes display two anomalies compared with the above and with all other basalts in West Antarctica. They include 143Nd/144Nd (0.512778-0.512789) values at Mt. Takahe and Mt. Siple that are 2σ lower than other West Antarctic basalts, and Ba/Nb, Ba/La, and Ba/Th values at Mt. Murphy and Mt. Takahe that are 3-8 times higher than normal OIB. Isotope and trace element data do not support crustal and lithospheric mantle contamination, or the presence of residual mantle amphibole or phlogopite as explanations of these anomalies. The apparent coincidence of these anomalies with the site of a pre-Cenozoic convergence zone along the Gondwanaland margin suggests a subduction influence. Major episodes of subduction and granitic plutonism took place in MBL during the Devonian, Permian, and Late Cretaceous. Relicts in the source region, of components from these subducted slabs, provide a credible explanation for the uncoupling of Ba from other large ion lithophile elements (LILE), for its erratic distribution, and for the anomalously low 143Nd/144Nd at Mt. Takahe. The last episode of subduction ended 85 Ma, and was followed by continental break-up, rifting and lithospheric attenuation that produced the West Antarctic rift as we know it today. Thus, the enigmatic geochemical signatures in these three volcanoes seem to have been preserved roughly 61-85 m.y. after subduction ended. New calculations of source melting depth and a new determination of lithospheric thickness suggest that the source of the anomalies resides in a fossil mélange diapir that rose from the Cretaceous subducting slab, became attached to the base of the lithosphere at 80-100 km depth, and remained there during the subsequent plate motion and source remobilization history of this region.

Change in the Nd isotopic composition of the bottom water and detrital sediments on the Bering Slope over the last 500 kyrs with implications for the formation of the North Pacific Intermediate Water

NASA Astrophysics Data System (ADS)

Jang, K.; Huh, Y.; Han, Y.

2015-12-01

The Bering Sea is a potential location for the formation of the North Pacific Intermediate/Deep Water (NPIW/NPDW) and may play an important role in the global heat distribution. We reconstructed the neodymium isotopic ratio (ɛNd) of authigenic Fe-Mn oxide coatings and detrital sediments on the Bering Slope (IODP Expedition 323 site U1345; water depth 1008 m) over the last 500 kyrs. The ɛNd is a quasi-conservative water mass tracer. We compared three different leaching techniques to assure that authigenic signals are captured without contamination from terrigenous sources: (1) leaching (3 hours) with 0.02 M hydroxylamine hydrochloride (HH) in 25% buffered acetic acid after decarbonation; sediment/solution (v/v) > 10, (2) leaching (1 hour) with 0.02 M HH in 25% buffered acetic acid without decarbonation; sediment/solution ~ 1, and (3) leaching (1 hour) with 0.005 M HH in 1.5% buffered acetic acid-0.003 M Na-EDTA without decarbonation; sediment/solution > 40. The low Al concentrations and less radiogenic ɛNdvalues indicated that method (2) is the most appropriate leaching process. The average ɛNd of the authigenic fraction over the last 500 kyrs is -3.3 ± 0.9 (1σ, n=38), with large temporal fluctuations. The ɛNd of authigenic and detrital fractions are well correlated (r2 ~ 0.66), suggesting that the bottom water composition in the Bering Sea was governed by terrigenous inflow from surrounding areas. Radiogenic ɛNd peaks (up to -1.9) seem to be influenced by radiogenic water inflow from the the Kamchatka or Aluetian arcs. The high bulk density and low b* values imply higher terrigenous versus biological contribution and enhanced sea ice formation. Subsequent brine formation would have triggered sinking of radiogenic surface water, forming the NPIW. On the other hand, non-radiogenic ɛNd troughs (down to -5.3) are observed at times of low bulk density and high b* values. We presume higher biological productivity which is supported by the high opal content at these intervals (Kanematsu et al., 2013). Sea level rise and boundary exchange with terrigenous sediment derived from N. America is a likely mechanism. This work was supported by the Basic Science Research Program through the NRF funded by Ministry of Science, ICT and Future Planning (No. 2014 0498836)

Decomposing Sources of Response Slowing in the PRP Paradigm

ERIC Educational Resources Information Center

Jentzsch, Ines; Leuthold, Hartmut; Ulrich, Rolf

2007-01-01

The mechanism underlying the reaction time (RT2) slowing to the 2nd of 2 successively presented stimuli (S1 and S2) in the psychological refractory period paradigm was investigated. Stimulus onset synchrony (SOA) between S1 and S2, contrast of S2, and Task 2 set-level compatibility was manipulated. Specifically, the authors used a…

Origin of depleted components in basalt related to the Hawaiian hot spot: Evidence from isotopic and incompatible element ratios

NASA Astrophysics Data System (ADS)

Frey, F. A.; Huang, S.; Blichert-Toft, J.; Regelous, M.; Boyet, M.

2005-02-01

The radiogenic isotopic ratios of Sr, Nd, Hf, and Pb in basaltic lavas associated with major hot spots, such as Hawaii, document the geochemical heterogeneity of their mantle source. What processes created such heterogeneity? For Hawaiian lavas there has been extensive discussion of geochemically enriched source components, but relatively little attention has been given to the origin of depleted source components, that is, components with the lowest 87Sr/86Sr and highest 143Nd/144Nd and 176Hf/177Hf. The surprisingly important role of a depleted component in the source of the incompatible element-enriched, rejuvenated-stage Hawaiian lavas is well known. A depleted component also contributed significantly to the ˜76-81 Ma lavas erupted at Detroit Seamount in the Emperor Seamount Chain. In both cases, major involvement of MORB-related depleted asthenosphere or lithosphere has been proposed. Detroit Seamount and rejuvenated-stage lavas, however, have important isotopic differences from most Pacific MORB. Specifically, they define trends to relatively unradiogenic Pb isotope ratios, and most Emperor Seamount lavas define a steep trend of 176Hf/177Hf versus 143Nd/144Nd. In addition, lavas from Detroit Seamount and recent rejuvenated-stage lavas have relatively high Ba/Th, a characteristic of lavas associated with the Hawaiian hot spot. It is possible that a depleted component, intrinsic to the hot spot, has contributed to these young and old lavas related to the Hawaiian hot spot. The persistence of such a component over 80 Myr is consistent with a long-lived source, i.e., a plume.

Investigation of luminescent properties of LaF3:Nd3+ nanoparticles

NASA Astrophysics Data System (ADS)

Wyrwas, Marek; Miluski, Piotr; Zmojda, Jacek; Kochanowicz, Marcin; Jelen, Piotr; Sitarz, Maciej; Dorosz, Dominik

2015-09-01

Lanthanum fluoride nanoparticles doped with Nd3+ ions obtained via solvothermal method have been presented. Doped nanoparticles were prepared in two-step method. Firstly rare-earth chlorides were synthesized from oxides and then they were used to prepare LaF3 particles. The luminescence spectra shows typical for crystalline materials Stark splitting at 880 nm corresponding 4F3/2 to 4I9/2 level transition and 1060 nm matching 4F3/2 to 4I11/2 level transition. The highest luminescence intensity was achieved for sample doped with 0.75% wt. of Nd3+, and the longest decay time for sample doped with 0.5% wt. which reached 328 μs. The XRD pattern analysis confirmed that obtained material consists of crystalline LaF3, the grain size was estimated from Sherrer's formula and equaled about 25nm.

Dielectric and AC conductivity studies of Nd substituted 0.8BaTiO{sub 3}-0.2(Bi{sub 0.5(1-x)}Nd{sub 0.5x}K{sub 0.5})TiO{sub 3} lead free ceramics

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

Ramesh, M. N. V.; Ramesh, K. V., E-mail: kv-ramesh5@yahoo.co.in

2016-05-23

0.8BaTiO{sub 3} – 0.2(Bi{sub 0.5(1-x)}Nd{sub 0.5x}K{sub 0.5})TiO{sub 3} (0.01 ≤ x ≤ 0.06) lead free ceramic materials have been prepared by solid state reaction method and followed by high energy ball milling process. X-ray diffraction studies confirm the tetragonal structure of the materials at room temperature. Lattice parameters and density are decreasing with increase of Nd substitution. Microstructure studies were done by using Scanning electron microscope and it found that grain size is decreasing with increase of Nd substitution. Temperature and frequency dependent dielectric studies reveal relaxor behaviour of the materials. Dielectric constant, dielectric loss and Curie temperature are decreasingmore » with Nd substitution. Maximum Curie temperature of 195°C was observed at 1 MHz for x=0.01 Nd substituted sample. Degree of diffuseness was calculated from the modified Curie-Weiss law and it is increasing with Nd substitution. AC conductivity is increasing with increase of Nd substitution and observed maximum activation energy of 0.52 eV for x=0.02 Nd substituted sample.« less

Pharmaceuticals and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs) in stormwater canals and Bayou St. John in New Orleans, Louisiana, USA.

PubMed

Boyd, Glen R; Palmeri, Jordan M; Zhang, Shaoyuan; Grimm, Deborah A

2004-10-15

Samples were collected from two stormwater canals and a recreational urban waterway known as Bayou St. John in New Orleans, Louisiana, USA and analyzed for a range of pharmaceuticals and personal care products (PPCPs) and endocrine disrupting chemicals (EDCs). Concentrations of 7 PPCPs and EDCs were measured by a method that provides for simultaneous extraction and quantification of the following compounds: clofibric acid, naproxen, ibuprofen, fluoxetine, clorophene, triclosan, bisphenol A. The method also was used as an indicator of the occurrence of estrogenic compounds by targeting estrone and 17beta-estradiol. The two canals (Orleans and London) are used to drain a portion of the city's stormwater directly into the Mississippi River or Lake Pontchartrain. Bayou St. John is located between the two canals and supplied with water from Lake Pontchartrain. Results from the 6-month sampling period indicated the following concentration ranges for the two stormwater canals: naproxen (ND - 145 ng/l), ibuprofen (ND - 674 ng/l), triclosan (ND - 29 ng/l) and bisphenol A (1.9-158 ng/l). Concentrations of these target analytes increased with cumulative rainfall. For bayou waters, only naproxen (2.1-4.8 ng/l) and bisphenol A (0.9-44 ng/l) were detected. Estrone was detected but determined non-quantifiable for multiple sampling events at the 3 sites. None of the other target analytes (clofibric acid, fluoxetine, clorophene, and 17beta-estradiol) were detected above their method detection levels. Results of this study demonstrate the occurrence of PPCPs and EDCs in New Orleans stormwater canals and Bayou St. John. Results also demonstrate the use of this analytical technique as an indicator of non-point source sewage contamination in New Orleans stormwater canals.

Electromagnetic and Microwave-Absorbing Properties of Plate-Like Nd-Ce-Fe Powder

NASA Astrophysics Data System (ADS)

Qiao, Ziqiang; Pan, Shunkang; Xiong, Jilei; Cheng, Lichun; Lin, Peihao; Luo, Jialiang

2017-01-01

Plate-like Ce x Nd2- x Fe17 ( x = 0.0, 0.1, 0.2, 0.3, 0.4) powders have been synthesized by an arc melting and high-energy ball milling method. The structure of the Nd-Ce-Fe powders was investigated by x-ray diffraction analysis. Their morphology and particle size distribution were evaluated by scanning electron microscopy and laser particle analysis. The saturation magnetization and electromagnetic parameters of the powders were characterized using vibrating-sample magnetometry and vector network analysis, respectively. The results reveal that the Ce x Nd2- x Fe17 ( x = 0.0, 0.1, 0.2, 0.3, 0.4) powders consisted of Nd2Fe17 single phase with different Ce contents. The particle size and saturation magnetization decreased with increasing Ce content. The resonant frequencies of ɛ″ and μ″ moved towards lower frequency with increasing Ce concentration. The minimum reflection loss value decreased as the Ce content was increased. The minimum reflection loss and absorption peak frequency of Ce0.2Nd1.8Fe17 with coating thickness of 1.8 mm were -22.5 dB and 7 GHz, respectively. Increasing the values of the complex permittivity and permeability could result in materials with good microwave absorption properties.

Structural, Geochemical, and Isotopic Studies on Magmatic Dyke Swarms of the South Shetland Islands Volcanic Arc, West Antarctica - Revealing the Geodynamic History

NASA Astrophysics Data System (ADS)

Kraus, S.; Miller, H.

2003-12-01

Between 2000 and 2002 areas of up to 100,000 m2 have been mapped at several locations of the South Shetland Islands, mainly on King George and Livingston Islands. A structural analysis of the dykes and the host rocks was undertaken, and about 250 dykes were sampled for geochemical studies. On Livingston Island six different strike directions were identified, yielding a reliable relative time sequence as deduced from field-relationships. Geochemically, these dykes can be separated into five different groups, correlating with the different strike directions, one of those groups comprising two directions. Analysis of the structural data shows, that at least on Livingston Island only minor changes of the tensional situation occurred. Geochemical data reveal that all dykes of the South Shetland Islands belong to a calc-alkaline, arc-related suite, ranging from primitive basalts to highly differentiated rhyolites. Interpretation of Sr isotopic data of the dykes proves difficult, as there are indications for sea-water induced Sr-alteration. Nd isotopic analysis yield better results, revealing a three-stage development from the oldest dykes (ɛ Nd -0.2 to 0.6) on Livingston Island towards a second, younger group (ɛ Nd 2.8 to 4.2, also Livingston), terminating with a third one (ɛ Nd 5.2 to 7.6), which includes the youngest dykes on Livingston and all dykes on King George and also Penguin Island. Either two mantle sources were involved, or the amount of crustal contamination changed considerately with time. It may have been high during initial arc volcanism, because of a still unstretched crust, then decreasing continually with progressing volcanism. In any case, the pattern reflects a chronological sequence corresponding with other authors' hypothesis of a migrating arc volcanism from SW to NE, i.e. from Livingston (older dykes) towards King George Island (younger dykes). Pb isotopic data, plottet together with MORB- and sediment-samples dredged from the Drake Passage, indicate a three-component mixture of the arc magma. Mixing of MORB- and sediment-sources alone cannot explain the observed pattern. An additional source, maybe the crust underlying the South Shetland block, was involved.

On the Assessment of Psychometric Adequacy in Correlation Matrices.

ERIC Educational Resources Information Center

Dziuban, Charles D.; Shirkey, Edwin C.

Three techniques for assessing the adequacy of correlation matrices for factor analysis were applied to four examples from the literature. The methods compared were: (1) inspection of the off diagonal elements of the anti-image covariance matrix S(to the 2nd) R(to the -1) and S(to the 2nd); (2) the Measure of Sampling Adequacy (M.S.A.), and (3)…

Spatial variations in geochemical characteristics of the modern Mackenzie Delta sedimentary system

NASA Astrophysics Data System (ADS)

Vonk, Jorien E.; Giosan, Liviu; Blusztajn, Jerzy; Montlucon, Daniel; Graf Pannatier, Elisabeth; McIntyre, Cameron; Wacker, Lukas; Macdonald, Robie W.; Yunker, Mark B.; Eglinton, Timothy I.

2015-12-01

The Mackenzie River in Canada is by far the largest riverine source of sediment and organic carbon (OC) to the Arctic Ocean. Therefore the transport, degradation and burial of OC along the land-to-ocean continuum for this riverine system is important to study both regionally and as a dominant representative of Arctic rivers. Here, we apply sedimentological (grain size, mineral surface area), and organic and inorganic geochemical techniques (%OC, δ13C-OC and Δ14C-OC, 143Nd/144Nd, δ2H and δ18O, major and trace elements) on particulate, bank, channel and lake surface sediments from the Mackenzie Delta, as well as on surface sediments from the Mackenzie shelf in the Beaufort Sea. Our data show a hydrodynamic sorting effect resulting in the accumulation of finer-grained sediments in lake and shelf deposits. A general decrease in organic carbon (OC) to mineral surface area ratios from river-to-sea furthermore suggests a loss of mineral-bound terrestrial OC during transport through the delta and deposition on the shelf. The net isotopic value of the terrestrial OC that is lost en route, derived from relationships between δ13C, OC and surface area, is -28.5‰ for δ13C and -417‰ for Δ14C. We calculated that OC burial efficiencies are around 55%, which are higher (∼20%) than other large river systems such as the Amazon. Old sedimentary OC ages, up to 12 14C-ky, suggest the delivery of both a petrogenic OC source (with an estimated contribution of 19 ± 9%) as well as a pre-aged terrestrial OC source. We calculated the 14C-age of this pre-aged, biogenic, component to be about 6100 yrs, or -501‰, which illustrates that terrestrial OC in the watershed can reside for millennia in soils before being released into the river. Surface sediments in lakes across the delta (n = 20) showed large variability in %OC (0.92-5.7%) and δ13C (-30.7‰ to -23.5‰). High-closure lakes, flooding only at exceptionally high water levels, hold high sedimentary OC contents (>2.5%) and young biogenic OC with a terrestrial or an autochthonous source whereas no-closure lakes, permanently connected to a river channel, hold sediments with pre-aged, terrestrial OC. The intermediate low-closure lakes, flooding every year during peak discharge, display the largest variability in OC content, age and source, likely reflecting variability in for example the length of river-lake connections, the distance to sediment source and the number of intermediate settling basins. Bank, channel and suspended sediment show variable 143Nd/144Nd values, yet there is a gradual but distinct spatial transition in 143Nd/144Nd (nearly three ε units; from -11.4 to -13.9) in the detrital fraction of lake surface sediments from the western to the eastern delta. This reflects the input of younger Peel River catchment material in the west and input of older geological source material in the east, and suggests that lake sediments can be used to assess variability in source watershed patterns across the delta.

Enrichment of 18O in the mantle sources of the Antarctic portion of the Karoo large igneous province

NASA Astrophysics Data System (ADS)

Heinonen, Jussi S.; Luttinen, Arto V.; Whitehouse, Martin J.

2018-03-01

Karoo continental flood basalt (CFB) province is known for its highly variable trace element and isotopic composition, often attributed to the involvement of continental lithospheric sources. Here, we report oxygen isotopic compositions measured with secondary ion mass spectrometry for hand-picked olivine phenocrysts from 190 to 180 Ma CFBs and intrusive rocks from Vestfjella, western Dronning Maud Land, that form an Antarctic extension of the Karoo province. The Vestfjella lavas exhibit heterogeneous trace element and radiogenic isotope compositions (e.g., ɛ Nd from - 16 to + 2 at 180 Ma) and the involvement of continental lithospheric mantle and/or crust in their petrogenesis has previously been suggested. Importantly, our sample set also includes rare primitive dikes that have been derived from depleted asthenospheric mantle sources ( ɛ Nd up to + 8 at 180 Ma). The majority of the oxygen isotopic compositions of the olivines from these dike rocks (δ18O = 4.4-5.2‰; Fo = 78-92 mol%) are also compatible with such sources. The olivine phenocrysts in the lavas, however, are characterized by notably higher δ18O (6.2-7.5‰; Fo = 70-88 mol%); and one of the dike samples gives intermediate compositions (5.2‒6.1‰, Fo = 83-87 mol%) between the other dikes and the CFBs. The oxygen isotopic compositions do not correlate with radiogenic isotope compositions susceptible to crustal assimilation (Sr, Nd, and Pb) or with geochemical indicators of pyroxene-rich mantle sources. Instead, δ18O correlates positively with enrichments in large-ion lithophile elements (especially K) and 187Os. We suggest that the oxygen isotopic compositions of the Vestfjella CFB olivines primarily record large-scale subduction-related metasomatism of the sub-Gondwanan mantle (base of the lithosphere or deeper) prior to Karoo magmatism. The overall influence of such sources to Karoo magmatism is not known, but, in addition to continental lithosphere, they may be responsible for some of the geochemical heterogeneity observed in the CFBs.

Influence of the Amazon River on the Nd isotope composition of deep water in the western equatorial Atlantic during the Oligocene-Miocene transition

NASA Astrophysics Data System (ADS)

Stewart, Joseph A.; Gutjahr, Marcus; James, Rachael H.; Anand, Pallavi; Wilson, Paul A.

2016-11-01

Dissolved and particulate neodymium (Nd) are mainly supplied to the oceans via rivers, dust, and release from marine sediments along continental margins. This process, together with the short oceanic residence time of Nd, gives rise to pronounced spatial gradients in oceanic 143Nd/144Nd ratios (εNd). However, we do not yet have a good understanding of the extent to which the influence of riverine point-source Nd supply can be distinguished from changes in mixing between different water masses in the marine geological record. This gap in knowledge is important to fill because there is growing awareness that major global climate transitions may be associated not only with changes in large-scale ocean water mass mixing, but also with important changes in continental hydroclimate and weathering. Here we present εNd data for fossilised fish teeth, planktonic foraminifera, and the Fe-Mn oxyhydroxide and detrital fractions of sediments recovered from Ocean Drilling Project (ODP) Site 926 on Ceara Rise, situated approximately 800 km from the mouth of the River Amazon. Our records span the Mi-1 glaciation event during the Oligocene-Miocene transition (OMT; ∼23 Ma). We compare our εNd records with data for ambient deep Atlantic northern and southern component waters to assess the influence of particulate input from the Amazon River on Nd in ancient deep waters at this site. εNd values for all of our fish teeth, foraminifera, and Fe-Mn oxyhydroxide samples are extremely unradiogenic (εNd ≈ - 15); much lower than the εNd for deep waters of modern or Oligocene-Miocene age from the North Atlantic (εNd ≈ - 10) and South Atlantic (εNd ≈ - 8). This finding suggests that partial dissolution of detrital particulate material from the Amazon (εNd ≈ - 18) strongly influences the εNd values of deep waters at Ceara Rise across the OMT. We conclude that terrestrially derived inputs of Nd can affect εNd values of deep water many hundreds of kilometres from source. Our results both underscore the need for care in reconstructing changes in large-scale oceanic water-mass mixing using sites proximal to major rivers, and highlight the potential of these marine archives for tracing changes in continental hydroclimate and weathering.

Radiogenic Isotope Constraints on Plume - Lithosphere Interaction Beneath the Snake River Plain

NASA Astrophysics Data System (ADS)

Hanan, B. B.; Shervais, J. W.; Vetter, S. K.

2006-12-01

The Snake River Plain (SRP), an 800 km swath of volcanic centers that stretch across southern Idaho to western Wyoming-Montana, represents about 16 Myr of volcanic activity that took place as the NA continent migrated over a relatively fixed magma source, or hotspot. Volcanic activity in the SRP began with the eruption of the main phase of the Columbia River Basalt Group (CRBG) at about 16.5 - 15 Ma through Paleozoic- Mesozoic lithosphere accreted to the Precambrian NA continental margin (1). At about 15 Ma, volcanism shifted to the east, across the cratonic margin into the SRP, and advanced with time to its current position on the Yellowstone Plateau (YP). Published major element, trace element, and He isotope systematics of the basaltic rocks are consistent with a deep, sub-lithospheric mantle source, similar to the source of ocean island basalts (OIBs). In contrast, the radiogenic isotopes of Pb, Sr, and Nd are indistinguishable from sub- continental mantle lithosphere (SCML) that underlies the SRP and YP. This conundrum has been a major problem for plume-oriented models for the SRP-YP hotspot. The Wyoming craton underlying the SRP has a stabilization age of around 2.8 Ga under the YP and eastern SRP area (2). Deep crustal xenoliths show a pattern of decreasing age (about 3.2-2.5 Ga) from east to west along the SRP (3,4). Compared to other Archean rocks, the Pb and Sr initial ratios are higher, and the Nd initial ratios are lower than expected for a depleted upper mantle source, suggesting a small amount of crustal material mixed into the SCML during late Archean subduction events (2). Concentrations of radiogenic incompatible elements in OIB-plume sources are nearly 100 times lower than found in the craton. Assimilation of small percentage fractional melts of the craton into large volume, larger degree partial melts derived from the plume mantle source would result in hybrid magmas whose isotopic compositions are controlled by the isotopic composition of the continental component. We tested this prediction with fifty basalts from along the SRP analyzed for major and trace contents and Pb, Sr, and Nd isotopes. The SRP Pb isotope results are consistent with mixing between an OIB-like plume component with 1% to 4% melt derived from about 2.8 Ga Wyoming-like enriched SCML and show that the relative amount of plume-like OIB component increases from 90-98% in the YP, to 98-99% in the central and western SRP. Basalts of the main phase CRBG (5), the central and eastern SRP, and the YP (6) show an overall decrease in 206Pb/204Pb and ^{143}Nd/^{144}Nd, variable 87Sr/86Sr, and increase in 207Pb/206Pb and ^{208}Pb/206Pb from west to east with distance from the Yellowstone caldera, with OIB-like values in Oregon and Washington toward values typical of the lower crust and lithosphere of the Wyoming Province along the SRP and YP. These results are consistent with a progressive decrease in craton thickness from east to west approaching the craton margin, a concomitant decrease in the age, and compositional heterogeneity in the lower crust and SCML beneath the SRP. (1) Camp and Ross, JGR 109, 2004; (2) Wooden and Mueller, EPSL 87, 1988; (3) Leeman et al., EPSL 75, 1985; (4) Wolf et al., GSA Abstracts with Programs 37, 2005; (5) Hooper, G3 1, 2000; (6) Doe, JGR 87, 1982.

Installation Restoration Program. Stage 3. Remedial Investigation/ Feasibility Study. Elmendorf Air Force Base, Alaska. Volume 5. Appendix G

DTIC Science & Technology

1990-05-01

Pentachloronitrobenzene ND mg/kg 2.5 S P henaceti n NO mg/kg 2- Picoline ND mg/kgI Pronamideh NO mg/kg 2.5I benzene ND mg/kg 2.5 2, 6-Di chi orophenol ND mg/kg 2.5 I...mg/kg 2.5 Pentachloronitrobenzene NO mg/kg 2.5 Phenaceti n ND mg/kg 2.5 2- Picoline ND mg/kg 2.5 Pronamide ND mg/kg 2.5 1 ,2,4,5-Tetrachloro benzene ND...Phenacetin ND mg/kg 2.5 2- Picoline ND mg/kg 2.5 Pronami de ND mg/kg 2.5 1,2,4,5-Tetrachlorobenzene ND mg/kg 2.5 2, 6-Di chi orophenol ND mg/kg 2.5 2-Methyl

Squamous cell carcinoma of cervical lymph nodes from an unknown primary site: The impact of neck dissection.

PubMed

Lou, Jianlin; Wang, Shengye; Wang, Kejing; Chen, Chao; Zhao, Jianqiang; Guo, Liang

2015-10-01

To investigate the treatment strategies of squamous cell carcinoma of cervical lymph nodes from an unknown primary site (SCCUP) and the value of neck dissection (ND). The study included 133 patients referred to the Zhejiang Cancer Hospital from 2001 to 2012, with 109 males and 24 females. Distribution of patients by N status was as follows: N1 - 14 cases; N2a - 21 cases; N2b - 78 cases; N2c - 7 cases; and N3 - 13 cases. 104 patients underwent surgeries of ND while 29 patients underwent nonsurgical treatment. Among 104 patients, 24 underwent classic radical ND, 16 modified ND, 53 selective ND, and 11 extended ND. The selection of surgical strategy was determined by the extent and location of disease. According to the range of ND, 50 patients underwent ND for Levels I-V, 46 for Levels II-V, 4 for Levels I-III, 3 for Levels II-VI, and 1 for Levels I-VI. The data were analyzed with SPSS version 16.0. The differences between groups were calculated by χ2 tests. The actual overall survival (OS) rates were calculated by the Kaplan-Meier method. Different factors affecting the OS were determined by the log-rank test on univariate analysis. Cox regression was used to evaluate the multivariate analysis. The 5-year OS rate of the whole cohort was 67.1%; and the median survival time was 70.0 months. The 5-year OS of ND group and of the non-ND group were 71.3% and 53.2%, respectively (P = 0.061). Cox analysis indicated that N stage (P = 0.000), bilateral neck metastasis (P = 0.001), extracapsular spread (ES) (P = 0.016), and ND (P = 0.028) were independent prognostic factors for the OS of SCCUP. 25 patients (18.8%) had neck recurrence or residue. The locoregional failure rate of ND group and of the non-ND group were 13.5% and 37.9%, respectively (P = 0.003). Logistic regression analysis indicated that higher N stage was the main risk factor for locoregional failure (P = 0.015). N stage, bilateral neck metastasis, ES, and ND were the main factors for the survival rate of SCCUP. N3 stage was the independent risk factor for locoregional failure. ND could significantly increase the locoregional control and may benefit the survival rate.

Near Infrared Optical Properties of Whole Human Blood and Blood Containing Nanoparticulates

NASA Astrophysics Data System (ADS)

Mimun, Lawrence C.; Yust, Brian; Nash, Kelly L.; Sardar, Dhiraj K.

2010-10-01

Whole human blood is optically characterized in the near infrared (NIR) with and without the addition of nanocrystals. The optical properties were obtained using the double-integrating sphere technique at the Nd excitation wavelength of 808 nm. Y2O3 and Nd^3+:Y2O3 nanoparticles were added in predetermined amounts to water, blood plasma, and whole blood samples, from which a computational analysis was conducted using the Kubelka-Munk calculational method, the Inverse Adding Doubling Method, and the Magic Light Monte Carlo Method to characterized the optical properties such as the absorption (μa) and scattering coefficients (μs) and the scattering anisotropy (g). Through comparison with control samples, the optical properties of each component (blood, plasma, and nanoparticles) can be determined individually, thus illuminating any changes due to the biological environment. The emission from the Nd^3+:Y2O3 particles through the blood is also detected thus exhibiting their usefulness as real world biological markers.

GlobiPack v. 1.0

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

Bartlett, Roscoe

2010-03-31

GlobiPack contains a small collection of optimization globalization algorithms. These algorithms are used by optimization and various nonlinear equation solver algorithms.Used as the line-search procedure with Newton and Quasi-Newton optimization and nonlinear equation solver methods. These are standard published 1-D line search algorithms such as are described in the book Nocedal and Wright Numerical Optimization: 2nd edition, 2006. One set of algorithms were copied and refactored from the existing open-source Trilinos package MOOCHO where the linear search code is used to globalize SQP methods. This software is generic to any mathematical optimization problem where smooth derivatives exist. There is nomore » specific connection or mention whatsoever to any specific application, period. You cannot find more general mathematical software.« less

The third/second generation PTH assay ratio as a marker for parathyroid carcinoma: evaluation using an automated platform.

PubMed

Cavalier, Etienne; Betea, Daniela; Schleck, Marie-Louise; Gadisseur, Romy; Vroonen, Laurent; Delanaye, Pierre; Daly, Adrian F; Beckers, Albert

2014-03-01

Parathyroid carcinoma (PCa) is rare and often difficult to differentiate initially from benign disease. Because PCa oversecretes amino PTH that is detected by third-generation but not by second-generation PTH assays, the normal 3rd/2nd generation PTH ratio (<1) is inverted in PCa (ie, >1). The objective of the investigation was to study the utility and advantages of automated 3rd/2nd generation PTH ratio measurements using the Liaison XL platform over existing manual techniques. The study was conducted at a tertiary-referral academic center. This was a retrospective laboratory study. Eleven patients with advanced PCa (mean age 56.0 y). The controls were patients with primary-hyperparathyroidism (n = 144; mean age 53.8 y), renal transplantation (n = 41; mean age 50.6 y), hemodialysis (n = 80; mean age 65.2 y), and healthy elderly subjects (n = 40; mean age 72.6 y). The median (interquartile range) 3rd/2nd generation PTH ratio was 1.16 (1.10-1.38) in the PCa group, which was significantly higher than the control groups: hemodialysis: 0.74 (0.71-0.75); renal transplant: 0.77 (0.73-0.79); primary hyperparathyroidism: 0.76 (0.74-0.78); healthy elderly: 0.80 (0.74-0.83). An inverted 3rd/2nd-generation PTH ratio (>1) was seen in 9 of 11 PCa patients (81.8%) and in 7 of 305 controls (2.3%): 3 of 80 hemodialysis (3.8%), and 4 of 144 primary-hyperparathyroidism patients (2.8%). Of four PCa patients who had a normal PTH ratio with the manual method, two had an inverted 3rd/2nd-generation PTH ratio with the automated method. Study of the 3rd/2nd-generation PTH ratio in large patient populations should be feasible using a mainstream automated platform like the Liaison XL. The current study confirms the utility of the inverted 3rd/2nd-generation PTH ratio as a marker of PCa (sensitivity: 81.8%; specificity: 97.3%).

Crystal Field Excitations Across High Tc Phase Diagram in La1 . 6 - x Nd0 . 4 Srx CuO4

NASA Astrophysics Data System (ADS)

Ma, Qianli; Maharaj, Dalini; Buhariwalla, Connor; Kolesnikov, Alexander; Stone, Matthew; Gaulin, Bruce

The family of high Tc superconductors(SC) La1 . 6 - x Nd0 . 4 Srx CuO4 (Nd-LSCO) has been studied as it displays a complex picture of the canonical hole-doped high Tc phase diagram. It displays static charge and spin stripe order over a range of Sr doping, which are optimized around x=0.125. Nd-LSCO evolves from an AFM insulating phase at x=0, to a region (0.05 0 . 25 . Here I present time-of-flight inelastic neutron scattering data of the Nd3+ crystalline electric field (CEF) levels on polycrystalline samples of Nd-LSCO over a range of compositions up to x=0.4. The experiments were performed on the SEQUOIA chopper spectrometer at the Spallation Neutron Source, and observe the evolution of the splitting of the J=9/2 multiplet appropriate to Nd3+ as a function of Sr concentrations (x=0.04,0.12,0.2,0.24 and 0.4) and (4K, 35K and 200K) temperature. We observe sharp CEF transitions near 21 meV and 27 meV at low x, evolve to a single transition near 24meV near x=0.1, in agreement with the onset of a superconducting ground state. NSERC.

1.083 μm laser operation in Nd,Mg:LiTaO3 crystal

NASA Astrophysics Data System (ADS)

Hu, P. C.; Hang, Y.; Li, R.; Gong, J.; Yin, J. G.; Zhao, C. C.; He, X. M.; Yu, T.; Zhang, L. H.; Chen, W. B.; Zhu, Y. Y.

2011-10-01

Nd,Mg:LiTaO3 single crystal with high optical quality was grown by Czochralski technique. Absorption and fluorescence spectra were investigated. The peak absorption cross section at 806.5 nm and peak emission cross section at 1091 nm are 6.81×10-20 and 3.28×10-20 cm2, respectively. The fluorescence lifetime was measured to be 129 μs. With a laser-diode as the pump source, a maximum 375 mW continuous-wave laser output at 1083 nm has been obtained with a slope efficiency of 7.2% with respect to the pump power.

Screening for an Allergic Response to 2nd Generation Biofuel Sources

EPA Science Inventory

Abstract for March 2014 Society of Toxicology Annual Meeting The use of cellulosic biofuels crops can potentially reduce our carbon footprint. However, they may have unintended ecological and health effects such as increased competitiveness and allergenicity...

Sediment provenance in the Laxmi Basin of the Arabian Sea during the last 800 kyrs

NASA Astrophysics Data System (ADS)

Khim, B. K.; Horikawa, K.; Asahara, Y.; Kim, J. E.; Ikehara, M.; Lee, J.

2017-12-01

International Ocean Discovery Program Expedition 355 conducted to drill 1109.4 m penetration at Site U1456 in the Laxmi Basin of the Arabian Sea. Four lithologic units are defined onboard at Site U1456 (Pandey et al., 2016). Unit I is 121 m long, consisting mostly of pelagic carbonates (nannofossil ooze and/or foraminifera-rich nannofossil ooze) interbedded with thin terrigenous (clay, silt, and sand) turbidite layers. The age model of Unit I was determined by the correlation of δ18O fluctuations of planktonic foraminifera (Globigerinoides ruber) to LR04 stacks, estimating 1.2 Ma. A total of 60 samples, collected in the context of magnetic susceptibility (MS) changes at a discrete interval from a composite section (Holes U1456A and U1456C) of Unit I, were analyzed to measure Nd and Sr isotopes of detrital fraction. Based on Nd and Sr isotopes, the sediment provenance in the Laxmi Basin during the last 800 kyrs was traced in response to the monsoon activity between the interglacial and glacial periods. ɛNd and 87Sr/86Sr vary in a range from -12.4 to -8.0 and from 0.712 to 0.727, respectively. The correlation between ɛNd and 87Sr/86Sr is quite linear, indicating that the sediments were provided mainly by two dominant sources. Considering the ɛNd and 87Sr/86Sr end-members of sediment sources (i.e., river sediments), the Tapi River and Narmada River are the main contributors of sediments to Site U1456 with a little influence by the modern Indus River. However, the glacial sediments from the Indus River and the Mahi River may supply an additional fraction, leading to less ɛNd and more 87Sr/86Sr at Site U1456. Judged by the sediment sources, the sediments in the Laxmi Basin are characterized by the mixture of different provenances. In addition, it should be noted that the low ɛNd and high 87Sr/86Sr values coincide largely with high MS and vice versa, irrespectively of the glacial-interglacial change. Thus, rather than the sediment provenances, ɛNd and 87Sr/86Sr values of the detrital fraction in the Laxmi Basin of the Arabian Sea have been more controlled by the sedimentary processes (pelagic, hemi-pelagic and turbidite) and depositional conditions related with the sea level changes in response to the Arabian Sea monsoon activity between the glacial and interglacial periods during the last 800 kyrs.

Sources of international migration statistics in Africa.

PubMed

1984-01-01

The sources of international migration data for Africa may be classified into 2 main categories: administrative records and 2) censuses and survey data. Both categories are sources for the direct measurement of migration, but the 2nd category can be used for the indirect estimation of net international migration. The administrative records from which data on international migration may be derived include 1) entry/departure cards or forms completed at international borders, 2) residence/work permits issued to aliens, and 3) general population registers and registers of aliens. The statistics derived from the entry/departure cards may be described as 1) land frontier control statistics and 2) port control statistics. The former refer to data derived from movements across land borders and the latter refer to information collected at international airports and seaports. Other administrative records which are potential sources of statistics on international migration in some African countries include some limited population registers, records of the registration of aliens, and particulars of residence/work permits issued to aliens. Although frontier control data are considered the most important source of international migration statistics, in many African countries these data are too deficient to provide a satisfactory indication of the level of international migration. Thus decennial population censuses and/or sample surveys are the major sources of the available statistics on the stock and characteristics of international migration. Indirect methods can be used to supplement census data with intercensal estimates of net migration using census data on the total population. This indirect method of obtaining information on migration can be used to evaluate estimates derived from frontier control records, and it also offers the means of obtaining alternative information on international migration in African countries which have not directly investigated migration topics in their censuses or surveys.

Strontium and neodymium isotopic evidence for the heterogeneous nature and development of the mantle beneath Afar (Ethiopia)

NASA Astrophysics Data System (ADS)

Betton, P. J.; Civetta, L.

1984-11-01

Neodymium isotope and REE analyses of recent volcanic rocks and spinel lherzolite nodules from the Afar area are reported. The 143Nd/ 144Nd ratios of the volcanic rocks range from 0.51286 to 0.51304, similar to the range recorded from Iceland. However, the 87Sr/ 86Sr ratios display a distinctly greater range (0.70328-0.70410) than those reported from the primitive rocks of Iceland. Whole rock samples and mineral separates from the spinel lherzolite nodules exhibit uniform 143Nd/ 144Nd ratios (ca. 0.5129) but varied 87Sr/ 86Sr ratios in the range 0.70427-0.70528. The Sr sbnd Nd isotope variations suggest that the volcanic rocks may have been produced by mixing between two reservoirs with distinct isotopic compositions. Two possible magma reservoirs in this area are the source which produced the "MORB-type" volcanics in the Red Sea and Gulf of Aden and the anomalous source represented by the nodule suite. The isotopic composition of the volcanics is compatible with mixing between these two reservoirs. It is shown that the anomalous source with a high 87Sr/ 86Sr ratio cannot have been produced by simple processes of partial melting and mixing within normal mantle. Instead the high 87Sr/ 86Sr is equated with a fluid phase. A primitive cognate fluid, subducted seawater or altered oceanic lithosphere may have been responsible for the generation of the source with a high 87Sr/ 86Sr ratio.

Origin and evolution of the Nakhla meteorite inferred from the Sm-Nd and U-Pb systematics and REE, Ba, Sr, Rb and K abundances

NASA Technical Reports Server (NTRS)

Nakamura, N.; Unruh, D. M.; Tatsumoto, M.; Hutchison, R.

1982-01-01

Analyses of whole rock and mineral separates from the Nakhla meteorite are carried out by means of Sm-Nd and U-Tn-Pb systematics and by determining their REE, Ba, Sr, Rb, and K concentrations. Results show that the Sm-Nd age of the meteorite is 1.26 + or - 0.7 b.y., while the high initial epsilon(Nd) value of +16 suggests that Nakhla was derived from a light REE-depleted, old planetary mantle source. A three-stage Sm-Nd evolution model is developed and used in combination with LIL element data and estimated partition coefficients in order to test partial melting and fractional crystallization models and to estimate LIL abundances in a possible Nakhla source. The calculations indicate that partial melting of the source followed by extensive fractional crystallization of the partial melt could account for the REE abundances in the Nakhla constituent minerals. It is concluded that the significantly younger age of Nakhla than the youngest lunar rock, the young differentiation age inferred from U-Th-Pb data, and the estimated LIL abundances suggest that this meteorite may have been derived from a relatively large, well-differentiated planetary body such as Mars.

Effect of Nd doping on structural, dielectric and thermodynamic properties of PZT (65/35) ceramic

NASA Astrophysics Data System (ADS)

Mohiddon, Md Ahamad; Kumar, Abhishek; Yadav, K. L.

2007-05-01

The influence of neodymium (Nd) addition on the phase formation and dielectric properties of Pb(Zr 0.65Ti 0.35)O 3 composition prepared from mixed oxide method was analyzed. Pellets were sintered in air and PbZrO 3 (PZ) atmosphere separately. Non-perovskite ZrO 2 phase was observed in samples which were sintered in air, also grain size was found to decrease with Nd doping in non-PZ environment samples. Decrease in transition temperature by 80 °C with increasing Nd concentration was observed in both set of samples. Maximum dielectric constant and dielectric losses are found to decrease with Nd doping. Complex impedance analysis revealed that grain boundary resistance increases with Nd doping. Thermodynamic parameters such as change in enthalpy, free energy and change in entropy were studied.

Draft Genome Sequence of Pseudoalteromonas sp. Strain ND6B, an Oil-Degrading Isolate from Eastern Mediterranean Sea Water Collected at a Depth of 1,210 Meters

DOE PAGES

Harris, Austin P.; Techtmann, Stephen M.; Stelling, Savannah C.; ...

2014-11-26

We report the draft genome of Pseudoalteromonas sp. strain ND6B, which is able to grow with crude oil as a carbon source. Strain ND6B was isolated from eastern Mediterranean Sea deep water at a depth of 1,210 m. The genome of strain ND6B provides insight into the oil-degrading ability of the Pseudoalteromonas species.

Composite, all-ceramics, high-peak power Nd:YAG/Cr(4+):YAG monolithic micro-laser with multiple-beam output for engine ignition.

PubMed

Pavel, Nicolaie; Tsunekane, Masaki; Taira, Takunori

2011-05-09

A passively Q-switched Nd:YAG/Cr(4+):YAG micro-laser with three-beam output was realized. A single active laser source made of a composite, all-ceramics Nd:YAG/Cr(4+):YAG monolithic cavity was pumped by three independent lines. At 5 Hz repetition rate, each line delivered laser pulses with ~2.4 mJ energy and 2.8-MW peak power. The M(2) factor of a laser beam was 3.7, and stable air breakdowns were realized. The increase of pump repetition rate up to 100 Hz improved the laser pulse energy by 6% and required ~6% increase of the pump pulse energy. Pulse timing of the laser-array beams can by adjusted by less than 5% tuning of an individual line pump energy, and therefore simultaneous multi-point ignition is possible. This kind of laser can be used for multi-point ignition of an automobile engine. © 2011 Optical Society of America

Rock magnetic parameters and Sr-Nd isotopes as tracers of continental erosion in Red Sea and in Gulf of Aden during the last 20,000 years

NASA Astrophysics Data System (ADS)

Rojas, V.; Bouilloux, A.; Meynadier, L.; Valet, J.-P.; Joron, J.-L.

2012-04-01

Over the past 20,000 years earth climate has undergone important changes that include the transition from the last glaciation to the Holocene with the retreat of glaciers, the modification of atmospheric circulation systems and hydrologic regimes. The production and transport of matter into the ocean was influenced by these variations in climatic conditions. In this study we considered the Red Sea and the Gulf of Aden as basins that offer a particular geographic and geological setting and that could be of interest in understanding climate variations and their effects in local erosion. The study of two cores in each side of the Bab-el-Mandeb strait (MD 92-1002 in the Gulf of Aden and MD 92-1008 in the Red Sea) allows the comparison between the open ocean and a more isolated basin. Additionally, this is an intertropical region influenced by African and Asian monsoons whose intensities can vary depending on climate and wind patterns. Erosion and matter transfer from the continents to these basins in response to climate changes can be studied using different approaches including rock magnetism, sedimentology and radiogenic isotopes. Neodymium isotope ratios (expressed here in ɛNd) are a useful tracer of oceanic sediments sources and type of transport and can be used as a signature of specific water masses. The main sources of Nd in oceans are fluvial and eolian inputs originated from the erosion of the continental crust. We measured ɛNd values in both cores of the silicate and carbonate phases, which correspond respectively to detrital and dissolved Nd. We observe differences between the isotopic records of the two basins. In the Gulf of Aden detrital and dissolved ɛNd values show large changes linked to the Glacial-Interglacial transition, in agreement with other studies in the equatorial Indian Ocean. Both signals decreased by 1.5 ɛNd units between the LGM and the Holocene. By comparing these results with those from the Red Sea, we observe a less clear decrease in ɛNd values (0.5 ɛNd units for the detrital fraction), reflecting the greater communication of the Gulf of Aden basin with the open ocean. Variations in the detrital ɛNd values suggest a change of the eolian particles source from the Sahara region during glacial periods, to the Arabian-Nubian shield during interglacial periods. An increase of the dissolved ɛNd values in both basins between 15 and 10 kyr indicates an intensification of precipitation in this region and, as a consequence, a preferential alteration of the basaltic terrain. The ɛNd data are compared with magnetic susceptibility and magnetic mineralogy data in order to discriminate between influences of continental erosion and weathering, and redox conditions in the basins during the considered period of time. We found an overall covariation of magnetic parameters with the detrital ɛNd and sea water ɛNd of both cores except for the H1 event in the Gulf of Aden. Strontium isotope measurements of the detrital fractions are in progress to constrain the origin of the sources.

Sr-Nd-Pb isotopic constraints on the nature of the mantle sources involved in the genesis of the high-Ti tholeiites from northern Paraná Continental Flood Basalts (Brazil)

NASA Astrophysics Data System (ADS)

Rocha-Júnior, Eduardo R. V.; Marques, Leila S.; Babinski, Marly; Nardy, Antônio J. R.; Figueiredo, Ana M. G.; Machado, Fábio B.

2013-10-01

There has been little research on geochemistry and isotopic compositions in tholeiites of the Northern region from the Paraná Continental Flood Basalts (PCFB), one of the largest continental provinces of the world. In order to examine the mantle sources involved in the high-Ti (Pitanga and Paranapanema) basalt genesis, we studied Sr, Nd, and Pb isotopic systematics, and major, minor and incompatible trace element abundances. The REE patterns of the investigated samples (Pitanga and Paranapanema magma type) are similar (parallel to) to those of Island Arc Basalts' REE patterns. The high-Ti basalts investigated in this study have initial (133 Ma) 87Sr/86Sr ratios of 0.70538-0.70642, 143Nd/144Nd of 0.51233-0.51218, 206Pb/204Pb of 17.74-18.25, 207Pb/204Pb of 15.51-15.57, and 208Pb/204Pb of 38.18-38.45. These isotopic compositions do not display any correlation with Nb/Th, Nb/La or P2O5/K2O ratios, which also reflect that these rocks were not significantly affected by low-pressure crustal contamination. The incompatible trace element ratios and Sr-Nd-Pb isotopic compositions of the PCFB tholeiites are different to those found in Tristan da Cunha ocean island rocks, showing that this plume did not play a substantial role in the PCFB genesis. This interpretation is corroborated by previously published osmium isotopic data (initial γOs values range from +1.0 to +2.0 for high-Ti basalts), which also preclude basalt generation by melting of ancient subcontinental lithospheric mantle. The geochemical composition of the northern PCFB may be explained through the involvement of fluids and/or small volume melts related to metasomatic processes. In this context, we propose that the source of these magmas is a mixture of sublithospheric peridotite veined and/or interlayered with mafic components (e.g., pyroxenites or eclogites). The sublithospheric mantle (dominating the osmium isotopic compositions) was very probably enriched by fluids and/or magmas related to the Neoproterozoic subduction processes. This sublithospheric mantle region may have been frozen and coupled to the base of the Parana basin lithospheric plate above which the Paleozoic subsidence and subsequent Early Cretaceous magmatism occurred.

Geochemical and Nd isotopic constraints for the origin of Late Archean turbidites from the Yellowknife area, Northwest Territories, Canada

NASA Astrophysics Data System (ADS)

Yamashita, Katsuyuki; Creaser, Robert A.

1999-10-01

A detailed geochemical and isotopic study of Late Archean turbidites and volcanic rocks from the Yellowknife area, Slave province, was undertaken to constrain the nature of exposed crust at the time of 2.6 to 2.7 Ga crustal consolidation. The ɛNdT values of the volcanic rocks range from +1.7 to -4.4. This variation can be produced by assimilation of pre-2.8 Ga basement by a depleted mantle-derived magma, possibly followed by fractional crystallization. The turbidites are typically metamorphosed to greenschist to amphibolite facies, and where metamorphosed to greenschist facies, different units of Bouma sequence can be observed. The different units of Bouma sequence were sampled and analyzed separately to evaluate the possible differences in geochemical and isotopic signatures. The geochemical data presented here is in accord with the previously proposed model that argues for a mixture of 20% mafic-intermediate volcanic rocks, +55% felsic volcanic rocks, and +25% granitic rocks as a source of these turbidites. However, our revised calculation with the new data presented here argues for 1 to 2% input from an ultramafic source, as well as somewhat higher input from mafic-intermediate volcanic sources in the upper shale units compared to the lower sand units. The ɛNdT values of the turbidites generally are lower in the upper shale units compared to the lower sand units. Detailed inspection of trace-element data suggest that this is not an artifact of rare earth element-rich heavy minerals concentrating in the lower sand units of the turbidites, but rather is a result of “unmixing” of detritus with different ɛNdT values during sediment transportation and deposition. The upper shale units of the turbidites are isotopically compatible with a derivation mainly from crustally contaminated volcanic rocks, similar to those exposed in the Yellowknife area. The lower sand units contain a higher proportion of westerly derived plutonic rock detritus, characterized by higher ɛNdT, suggesting that there are area(s) west of Yellowknife not underlain by older (2.8-4.0 Ga) basement. The trace-element characteristics of these turbidites (i.e., Cr, Ni, La, Th, Sc, Eu/Eu∗, and GdN/YbN) are distinct from those of typical post-Archean turbidites. This observation is consistent with the models that predict that the chemical composition of the upper continental crust was slightly different in the Archean compared to post-Archean time.

Two-photon momentum density in La2-xSrxCuO4 and Nd2-xCexCuO4

NASA Astrophysics Data System (ADS)

Blandin, P.; Massidda, S.; Barbiellini, B.; Jarlborg, T.; Lerch, P.; Manuel, A. A.; Hoffmann, L.; Gauthier, M.; Sadowski, W.; Walker, E.; Peter, M.; Yu, Jaejun; Freeman, A. J.

1992-07-01

We present calculations of the electron-positron momentum density for the high-Tc superconductors La2-xSrxCuO4 and Nd2-xCexCuO4, together with experimental two-dimensional angular correlation of annihilation radiation (2D-ACAR) for Nd2-xCexCuO4. The calculations are based on first-principles electronic structure obtained using the full-potential linearized augmented-plane-wave and the linear muffin-tin orbital methods. Our results indicate a non-negligible overlap of the positron wave function with the CuO2 plane electrons responsible for the Fermi surfaces in these compounds. Therefore, these compounds may be well suited for investigating Fermi-surface-related effects. After the folding of umklapp terms according to Lock, Crisp, and West, the predicted Fermi-surface breaks are mixed with strong effects induced by the positron wave function in La2-xSrxCuO4, while their resolution is better in Nd2-xCexCuO4. A comparison of our calculations with the most recent experimental results for La2-xSrxCuO4 shows good agreement. For Nd2-xCexCuO4 good agreement is observed between theoretical and experimental 2D-ACAR profiles.

Born Lucky: The Institutional Sources behind the Third United States Army Headquarters’ Procedures in Northwest Europe, 1944-45

DTIC Science & Technology

2014-05-22

Engineer Bn., Co. B, 942nd Engineer Avn . Bn., Third US Army, 1 August 1944- 9 May 1945: Vol. I, The Operations, After Action Report (Germany...practitioners are willing to investigate the possibilities. 69 BIBLIOGRAPHY 652nd Engineer Bn., Co. B, 942nd Engineer Avn . Bn. Third US Army, 1 August

Changes in Equatorial Atlantic Ocean Thermohaline Circulation Across the Mid-Pleistocene Transition

NASA Astrophysics Data System (ADS)

Yehudai, M.; Kim, J.; Seguí, M. J.; Goldstein, S. L.; Pena, L. D.; Haynes, L.; Hoenisch, B.; Farmer, J. R.; Ford, H. L.; Raymo, M. E.; Bickert, T.

2016-12-01

The Mid-Pleistocene Transition (MPT) marked a change in the duration of glacial-interglacial cycles from 41 to 100kyr between 1.3-0.7 Ma. A recent study (Pena and Goldstein, Science, 2014) from the Southern Atlantic Ocean found evidence for major disruptions in the global thermohaline circulation (THC) between MIS 25-21 ( 950-850ka), which may have triggered intensified glacial periods and the onset of the 100 kyr cycles. We report new Nd isotope data on Fe-Mn oxide encrusted foraminifera and fish debris from ODP Site 926 (3.719N, 42.908W, 3598m) between 1.2-0.4 Ma, in order to evaluate changes in the THC in the equatorial Atlantic, through comparison with North and South Atlantic sites. The ODP 926 ɛNd values fall in-between those in the North Atlantic (DSDP 607) and South Atlantic (ODP 1088 and 1090) throughout the studied interval, consistent with mixing between northern and southern end-members, and supporting the interpretation that the data represent the THC signal at this site. Pre-MPT data show smaller glacial-interglacial differences compared to the greater post-MPT glacial-interglacial variability. As Pena and Goldstein (2014) observed in the South Atlantic, during MIS 23 at 900 ka, ɛNd values do not shift significantly toward North Atlantic more negative values, consistent with a weak THC through this critical weak interglacial. Comparing ODP 926 and DSDP 607 data, ɛNd values converge during most interglacial peaks (excepting MIS 23) and diverge otherwise. This observation indicates that northern-sourced water masses dominate the site during peak interglacials, and confirms that the THC has been strongest during peak interglacials throughout the studied interval. Otherwise, diverging ɛNd values indicate a stronger southern-source signal and weaker northern-source signal at the ODP 926 site. This confirms that there was an active but variable THC system before, during, and after the MPT, with stronger deep water export from the North Atlantic during interglacials.

Nd, Pb, Sr, and O isotopic characterization of Saudi Arabian Shield terranes

USGS Publications Warehouse

Stoeser, D.B.; Frost, C.D.

2006-01-01

New Nd, Sr and O isotopic data for granitoid rocks of the Saudi Arabian Shield are presented together with published Nd, Pb, Sr and O isotopic data and all available geologic and geochronologic information to re-evaluate the terranes defined for the Saudi Arabian part of the Arabian-Nubian Shield. Three groups of terranes are identified: 1) the western arc terranes, 2) the eastern arc terranes, and 3) the Khida terrane. The Khida terrane is the only terrane composed of pre-Neoproterozoic continental crust. The western arc terranes are of oceanic arc affinity, and have the least radiogenic Pb and Sr and most radiogenic Nd isotopic compositions and some of the lowest ??18O values of any rocks of the Saudi Arabian Shield. Although some previous studies have characterized the eastern arc terranes as of continental affinity, this study shows that they too are composed of Neoproterozoic oceanic arcs, although their sources have slightly elevated 208Pb/204Pb, Nd, Sri, and ??18O values compared to the western arc terranes. These data suggest that either the isotopic composition of the mantle source for the western arc terranes is more depleted than that of the eastern arc terranes or the eastern arc terranes have been mixed with a small amount of cratonic source material, or both. We further elaborate on the Hulayfah-Ad Dafinah fault zone as a major boundary within the Saudi Arabian portion of the East African Orogen. With further study, its northern extension may be shown to pass through what has been defined as the Hail terrane, and its southern extension appears to lie under cover east of the Tathlith-Malahah terrane and extend into Yemen. It may represent the collision zone between East and West Gondwana, and at the very least it is an important suture between groups of arc terranes of contrasting isotopic composition caught between two converging continents.

Extreme isotopic variations in the upper mantle: evidence from Ronda

NASA Astrophysics Data System (ADS)

Reisberg, Laurie; Zindler, Alan

1986-12-01

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

The peculiar geochemical signatures of São Miguel (Azores) lavas: Metasomatised or recycled mantle sources?

NASA Astrophysics Data System (ADS)

Beier, Christoph; Stracke, Andreas; Haase, Karsten M.

2007-07-01

The island of São Miguel, Azores consists of four large volcanic systems that exhibit a large systematic intra-island Sr-Nd-Pb-Hf isotope and trace element variability. The westernmost Sete Cidades volcano has moderately enriched Sr-Nd-Pb-Hf isotope ratios. In contrast, lavas from the easternmost Nordeste volcano have unusually high Sr and Pb and low Nd and Hf isotope ratios suggesting a long-term evolution with high Rb/Sr, U/Pb, Th/Pb, Th/U and low Sm/Nd and Lu/Hf parent-daughter ratios. They have trace element concentrations similar to those of the HIMU islands, with the exception of notably higher alkali element (Cs, Rb, K, Ba) and Th concentrations. The time-integrated parent-daughter element evolution of both the Sete Cidades and Nordeste source matches the incompatibility sequence commonly observed during mantle melting and consequently suggests that the mantle source enrichment is caused by a basaltic melt, either as a metasomatic agent or as recycled oceanic crust. Our calculations show that a metasomatic model involving a small degree basaltic melt is able to explain the isotopic enrichment but, invariably, produces far too enriched trace element signatures. We therefore favour a simple recycling model. The trace element and isotopic signatures of the Sete Cidades lavas are consistent with the presence of ancient recycled oceanic crust that has experienced some Pb loss during sub-arc alteration. The coherent correlation of the parent-daughter ratios (e.g. Rb/Sr, Th/U, U/Pb) and incompatible element ratios (e.g. Nb/Zr, Ba/Rb, La/Nb) with the isotope ratios in lavas from the entire island suggest that the Sete Cidades and Nordeste source share a similar genetic origin. The more enriched trace element and isotopic variations of Nordeste can be reproduced by recycled oceanic crust in the Nordeste source that contains small amounts of evolved lavas (˜ 1-2%), possibly from a subducted seamount. The rare occurrence of enriched source signatures comparable to Nordeste may be taken as circumstantial evidence that stirring processes in the Earth's mantle are not able to homogenise material within the size of seamounts over timescales of mantle recycling.

Nd3+-doped heavy metal oxide based multicomponent borate glasses for 1.06 μm solid-state NIR laser and O-band optical amplification applications

NASA Astrophysics Data System (ADS)

Lakshminarayana, G.; Kaky, Kawa M.; Baki, S. O.; Lira, A.; Meza-Rocha, A. N.; Falcony, C.; Caldiño, U.; Kityk, I. V.; Méndez-Blas, A.; Abas, A. F.; Alresheedi, M. T.; Mahdi, M. A.

2018-04-01

Nd3+-doped glasses in the composition (50-x) B2O3-10 PbO-10 BaO-10 Al2O3-10 ZnO-10 Na2O-(x) Nd2O3 (x = 0.0, 0.1, 0.25, 0.5, 0.75, 1.0, 1.5, and 2.0 mol %) were fabricated using melt quenching method. Upon 592 nm visible and 808 nm LD excitations, the luminescence spectra show a strong 4F3/2 → 4I11/2 (1.06 μm) emission transition, and two less intense 4F3/2 → 4I9/2 (0.89 μm) and 4F3/2 → 4I13/2 (1.331 μm) emission transitions. The intensity of such emissions increases up to 0.5 mol % Nd3+, and above this doping level, quenching occurs. For 0.5 mol % Nd3+-doped glass, following Judd-Ofelt intensity parameters and emission spectrum, AR, τR, βR and βexp, including Δλeff,σem(λp), (σem × (Δλeff)) and (σem × (τrad)), are derived for Nd3+ ion 4F3/2 → 4I11/2 and 4F3/2 → 4I13/2 fluorescence transitions. The highest σem(λp) for the 1.06 and 1.331 μm fluorescence bands are found to be 6.216 × 10-20 and 2.295 × 10-20cm2, respectively. The 4F3/2 level lifetimes are found to decrease with an increase in Nd2O3 content and the decay curves of the glass up to 1.5 mol % Nd3+ exhibit single exponential nature. From 'τexp' of the Nd3+: 4F3/2 level, quantum efficiency (η), (σem × (τexp)), and saturation intensity (IS) are 48.87%, 51.09 × 10-25 cm2s and 3.67 × 108 W/m2, respectively, for the 0.5 mol % Nd3+-doped glass. Higher thermal stability, very low χ, high AR, large βexp., moderate τR, large gain bandwidth and high optical gain values indicate that 0.5 mol % Nd3+-doped glass could be a potential gain medium for solid-state NIR lasers at 1.06 μm. Moreover, for the 1.331 μm emission, large Δλeff and the theoretical gain coefficient value of 1.579 dB/cm, evaluated with an excited Nd3+ ion fractional factor of 0.6, indicate that this glass might be a promising candidate in developing O-band optical fiber amplifiers.

Interactions between barley grain processing and source of supplemental dietary fat on nitrogen metabolism and urea-nitrogen recycling in dairy cows.

PubMed

Gozho, G N; Hobin, M R; Mutsvangwa, T

2008-01-01

The objective of this study was to determine the effects of methods of barley grain processing and source of supplemental fat on urea-N transfer to the gastrointestinal tract (GIT) and the utilization of this recycled urea-N in lactating dairy cows. Four ruminally cannulated Holstein cows (656.3 +/- 27.7 kg of BW; 79.8 +/- 12.3 d in milk) were used in a 4 x 4 Latin square design with 28-d periods and a 2 x 2 factorial arrangement of dietary treatments. Experimental diets contained dry-rolled barley or pelleted barley in combination with whole canola or whole flaxseed as supplemental fat sources. Nitrogen balance was measured from d 15 to 19, with concurrent measurements of urea-N kinetics using continuous intrajugular infusions of [15N 15N]-urea. Dry matter intake and N intake were higher in cows fed dry-rolled barley compared with those fed pelleted barley. Nitrogen retention was not affected by diet, but fecal N excretion was higher in cows fed dry-rolled barley than in those fed pelleted barley. Actual and energy-corrected milk yield were not affected by diet. Milk fat content and milk fat yield were higher in cows fed dry-rolled barley compared with those fed pelleted barley. Source of supplemental fat did not affect urea-N kinetics. Urea-N production was higher (442.2 vs. 334.3 g of N/d), and urea-N entering the GIT tended to be higher (272.9 vs. 202.0 g of N/d), in cows fed dry-rolled barley compared with those fed pelleted barley. The amount of urea-N entry into the GIT that was returned to the ornithine cycle was higher (204.1 vs. 159.5 g of N/d) in cows fed dry-rolled barley than in pelleted barley-fed cows. The amount of urea-N recycled to the GIT and used for anabolic purposes, and the amounts lost in the urine or feces were not affected by dietary treatment. Microbial nonammonia N supply, estimated using total urinary excretion of purine derivatives, was not affected by diet. These results show that even though barley grain processing altered urea-N entry into the GIT, the utilization of this recycled urea-N for microbial production was unaffected as the additional urea-N, which entered the GIT was returned to ureagenesis.

Isotopic Equilibrium in Mature Oceanic Lithosphere: Insights From Sm-Nd Isotopes on the Corsica (France) Ophiolites

NASA Astrophysics Data System (ADS)

Rampone, E.; Hofmann, A. W.; Raczek, I.; Romairone, A.

2003-12-01

In mature oceanic lithosphere, formed at mid-ocean ridges, residual mantle peridotites and associated magmatic crust are, in principle, linked by a cogenetic relationship, because the times of asthenospheric mantle melting and magmatic crust production are assumed to be roughly coheval. This implies that oceanic peridotites and associated magmatic rocks should have similar isotopic compositions. Few isotope studies have been devoted to test this assumption. At mid-ocean ridges, similar Nd isotopic compositions in basalts and abyssal peridotites have been found by Snow et al. (1994), thus indicating that oceanic peridotites are indeed residues of MORB melting. By contrast, Salters and Dick (2002) have documented Nd isotope differences between abyssal peridotites and associated basalts, with peridotites showing higher 143Nd/144Nd values, and they concluded that an enriched pyroxenitic source component is required to explain the low end of the 143Nd/144Nd variation of the basalts. Here we present Sm/Nd isotope data on ophiolitic mantle peridotites and intruded gabbroic rocks from Mt.Maggiore (Corsica, France), interpreted as lithosphere remnants of the Jurassic Ligurian Tethys ocean. The peridotites are residual after low-degree (<10%) fractional melting. In places, spinel peridotites grade to plagioclase-rich impregnated peridotites. Clinopyroxene separates from both spinel- and plagioclase- peridotites display high 147Sm/144Nd (0.49-0.59) and 143Nd/144Nd (0.513367-0.513551) ratios, consistent with their depleted signature. The associated gabbros have Nd isotopic compositions typical of MORB (143Nd/144Nd = 0.51312-0.51314). Sm/Nd data on plag, whole rock and cpx from an olivine gabbro define an internal isochron with an age of 162 +/- 10 Ma, and an initial epsilon Nd value (9.0) indicating a MORB-type source. In the Sm-Nd isochron diagram, the peridotite data also conform to the above linear array, their initial (160 Ma) epsilon Nd values varying in the range 7.6-8.9. Sm/Nd isotopic compositions of the peridotites are therefore consistent with a Jurassic age of melting and melt impregnation, and point to isotopic compositional similarities between depleted peridotites and associated magmatic rocks. In a regional geodynamic context, Sm/Nd isotope data for the Mt.Maggiore gabbro-peridotite association represent the first record of the attainment of a mature oceanic stage of the Ligurian Tethys ocean. Also, the data presented provide striking evidence of the existence of isotopic equilibrium between melts and their mantle residue. References Snow et al. (1994), Nature 371, 57-60. Salters and Dick (2002), Nature 418,68-72.

Growth and optical properties of Co,Nd:LaMgAl11O19

NASA Astrophysics Data System (ADS)

Xu, Peng; Xia, Changtai; Di, Juqing; Xu, Xiaodong; Sai, Qinglin; Wang, Lulu

2012-12-01

Nd,Co:LaMgAl11O19 (abbreviated as Co,Nd:LMA) was grown using the Czochralski method. The structure, polarized absorption spectrum, fluorescence spectrum, and fluorescence decay time were analyzed. The as-grown crystal had very wide absorption bands at 794 nm, which can be pumped by GaAs laser diode without temperature stabilization. Two strong emission bands were present at 1056 nm and 1082 nm with full-width at half-maximum (FWHM) of 6 and 8 nm, respectively. The large FWHM is due to the inhomogeneity of the Nd ion sites. The lifetimes of the 4F3/2 manifold of Co,Nd:LMA at room temperature monitored at 905 nm, 1056 nm, and 1344 nm were 292, 288, and 350 μs, respectively, which was caused by the different contribution of the three different sites with D3h and C2v symmetry. The absorption band of Co is from 1.3 μm to 1.6 μm, and Co,Nd:LMA still has a strong emission around the 1.38 μm, indicating that the Co,Nd:LMA can be applied as a potential self-Q-switched material operating at 1.3 μm.

Serca2a and Na{sup +}/Ca{sup 2+} exchanger are involved in left ventricular function following cardiac remodelling of female rats treated with anabolic androgenic steroid

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

Nascimento, Andrews Marques do; Lima, Ewelyne Mira

Anabolic-androgenic steroids are misused, including by women, but little is known about the cardiovascular effects of these drugs on women. Aim: To evaluated the effects of nandrolone decanoate (ND) and resistive physical exercise on cardiac contractility in young female rats. Main methods: Female Wistar rats were separated into 4 groups: C (untrained animals); E (animals were submitted to resistance exercise by jumping in water 5 times per week); ND (animals were treated with ND, 20 mg/kg/week for 4 weeks); and NDE (trained and treated). The haemodynamic parameters (+ dP/dt{sub max}, − dP/dt{sub min} and Tau) were assessed in the leftmore » ventricle. The heart was collected for histological analyses and collagen deposition. The gastrocnemius muscle was weighed, and hypertrophy was assessed by the ratio of their weights to gastrocnemius/tibia length. The expression of calcium handling proteins was measured by western blot analysis. Results: ND treatment and physical exercise increased cardiac contractility and relaxation. In addition, ND promoted increases in phospholamban phosphorylated (p-PLB) and isoforms of sarcoplasmic/endoplasmic reticulum calcium ATPase 2 (SERCA2a) expression, while resistance exercise increased the phosphorylation of PLB and expression of Na{sup +}/Ca{sup 2+} exchangers (NCX). Cardiac hypertrophy and collagen deposition were observed after ND treatment. Conclusion: Regulatory components of cytosolic calcium, such as SERCA2a and p-PLB, play important roles in modulating the contractility and relaxation effects of ND in females. - Highlights: • ND and resistive exercise enhanced the cardiac function and increased expression of cytosolic calcium regulatory components.« less

Application of the dual-kinetic-balance sets in the relativistic many-body problem of atomic structure

NASA Astrophysics Data System (ADS)

Beloy, Kyle; Derevianko, Andrei

2008-05-01

The dual-kinetic-balance (DKB) finite basis set method for solving the Dirac equation for hydrogen-like ions [V. M. Shabaev et al., Phys. Rev. Lett. 93, 130405 (2004)] is extended to problems with a non-local spherically-symmetric Dirac-Hartree-Fock potential. We implement the DKB method using B-spline basis sets and compare its performance with the widely- employed approach of Notre Dame (ND) group [W.R. Johnson, S.A. Blundell, J. Sapirstein, Phys. Rev. A 37, 307-15 (1988)]. We compare the performance of the ND and DKB methods by computing various properties of Cs atom: energies, hyperfine integrals, the parity-non-conserving amplitude of the 6s1/2-7s1/2 transition, and the second-order many-body correction to the removal energy of the valence electrons. We find that for a comparable size of the basis set the accuracy of both methods is similar for matrix elements accumulated far from the nuclear region. However, for atomic properties determined by small distances, the DKB method outperforms the ND approach.

Temperature sensor based on ladder-level assisted thermal coupling and thermal-enhanced luminescence in NaYF4: Nd³⁺.

PubMed

Tian, Xiuna; Wei, Xiantao; Chen, Yonghu; Duan, Changkui; Yin, Min

2014-12-01

NaYF4: Nd³⁺ microprisms were synthesized by a hydrothermal method. The bands of near-infrared (NIR) luminescence originating from the 4F3/2, 4F5/2 and 4F7/2 levels of Nd³⁺ ions in NaYF4: Nd³⁺ microcrystals were measured under 574.8 nm excitation at various temperatures from 323 to 673 K. The fluorescence intensity ratios (FIRs) between any two of the three bands change monotonically with temperature and agree with the prediction assuming thermal couplings. A large relative temperature sensitivity of 1.12% K⁻¹ at 500K is reached with the FIR of 4F7/2 to 4F3/2 levels. In addition, anti-Stokes fluorescence from 4F5/2 level (740 nm) and 4F5/2,7/2 levels (740 nm and 803 nm) of Nd³⁺ ions was studied meticulously under 793.8 nm and 864.2 nm excitations, respectively. The intensities were shown to be greatly enhanced as temperature increases, and the 740 nm band from 4F7/2 level at 458 K increases in intensity by 170 fold relative to that at 298 K under the 793.8 nm excitation.

Near-infrared-to-near-infrared down-shifting and upconversion luminescence of KY{sub 3}F{sub 10} with single dopant of Nd{sup 3+} ion

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

Lin, Huihong; State Key Laboratory of Luminescence Materials and Devices and Institute of Optical Communication Materials, South China University of Technology, Guangzhou 510641; Yu, Ting

2016-01-25

We have studied the structural and near-infrared (NIR) luminescent properties of KY{sub 3}F{sub 10} phosphors, singly doped with Nd{sup 3+} serving as both sensitizer and activator. With a single laser diode at the wavelength of 808 nm as a pump source, simultaneous NIR-to-NIR upconversion (UC) and down-shifting (DS) emissions are effectively achieved, due to the specific energy levels of Nd{sup 3+} dopant and the low phonon energy of the host. The luminescence mechanism related to energy transfer is discussed. The luminescence can be modulated through controlling the population of Nd{sup 3+}:{sup 4}F{sub 3/2} state in our experiment. Interestingly, both UC andmore » DS emissions of the material fall within the dual biological window, suggesting that the prepared phosphors have potential applications in the bioimaging field.« less

[Louse-borne typhus potential and new technologies in prediction of epidemic louse-borne typhus outburst].

PubMed

Boev, B V; Lobanov, A V; Khudobin, V V

2008-01-01

Features of louse-borne typhus in Russia in the middle of 20th century are considered. Study of the infection source, blood serum in patient after epidemic louse-borne typhus (ELBT) and agent (louse) was performed on territory with high morbidity of pediculosis and ELBT in the years of 2nd world war. New materials of seroimmunological examinations are represented. Priority data of lice morphology based on morphometrical data of lice, collected in Russia and world collection in Berlin are shown. Methods of ELBT prediction are given, special attention is paid to development of mathematic prognostic models based on new technologies.

Characterization of pulsed (plasma focus) neutron source with image plate and application to neutron radiography

NASA Astrophysics Data System (ADS)

Andola, Sanjay; Niranjan, Ram; Shaikh, A. M.; Rout, R. K.; Kaushik, T. C.; Gupta, S. C.

2013-02-01

Plasma focus device of Mather type developed in house has been used first time for neutron radiography of different objects. The device gives (1.2±0.3) ×109 neutrons per pulse produced by D-D fusion reaction with a pulse width of 50±5 ns. The method involves exposing sample to be radiographed to thermalized D-D neutrons and recording the image on Fuji-film BAS-ND image plates. The thermal neutron component of the moderated beam was estimated using two image plates: a conventional IP for X-rays and gamma rays, and an IP doped with Gd for detecting neutrons.

Correlation between impurity distribution and location of ferroelectric domain walls in Nd : Mg : LiNbO 3 single crystal

NASA Astrophysics Data System (ADS)

Naumova, I. I.; Evlanova, N. F.; Blokhin, S. A.; Lavrishchev, S. V.

1998-04-01

Using selective chemical etching, scanning electron microscope (SEM) and wave dispersive X-ray (WDX) microanalysis we showed that the ferroelectric domain walls coincide with the maxima and minima Nd-impurity modulation in a periodically poled Nd : Mg : LiNbO 3 crystal grown by the Czochralski method along the normal to the (0 1 1¯ 2) face. Asymmetric form of the Nd-modulation produces nonequal positive and negative domains for one period. Variations of instantaneous rate of growth were estimated for facet and nonfacet crystal region in the framework of Burton-Prim-Slichter theory.

Sr-Nd isotopes constrain on the deposit history of the basins in the Gulf of Mexico

NASA Astrophysics Data System (ADS)

Li, Y.; Jiang, S.

2015-12-01

The Brazos-Trinity Basin IV and Ursa Basin are situated on the northern slope of the Gulf of Mexico. The Ursa basin lies in the center of late Pleistocene Mississippi River deposition, received the sediment deposition during Marine Isotope Stage (MIS) 2- 4. The Brazos-Trinity Basin IV belongs to a part of the Brazos-Trinity fan, it recorded the turbidite deposition and hemiplegic deposition during MIS1- 5. The Sr and Nd isotopic composition of the detrital composition of the sediment in both basins indicates the change of the sediment provenance during the basin-filled process. In the Ursa basin, The difference of 87Sr/86Sr ratio and ɛNd of the detrital component between MIS1,2 (87Sr/86Sr ~ 0.7219 - 0.7321, ɛNd ~ -12 - -13.4) and MIS3,4(87Sr/86Sr ~ 0.7310 - 0.7354, ɛNd ~ -16 - -17.9) is suggested to be related with the provenance change of the detrital particles since LGM. The addition of detrital particle from Appalachians with less radiogenic 87Sr/86Sr and positive ɛNd altered the character of the sediment of the Mississippi River during the last glaciation and deglaciation. In the Brazos-Trinity Basin IV, the narrow range of 87Sr/86Sr and ɛNd indicate that the sediment source of Brazos-Trinity Basin IV had not changed obviously during MIS5e to MIS2, mostly from coastal rivers such as Brazos River, Trinity River and Sabine River. The pre-fan with 87Sr/86Sr ~0.735 and ɛNd ~ -14.5 to -16.9, which is very similar to the deep sediment in the Ursa Basin with 87Sr/86Sr ~0.733 to 0.735 and ɛNd ~ -16 to -18. It is suggested that sediments of the pre-fan of the Brazos-Trinity Basin IV were supplied from the ancestral Mississippi River Delta during the low sea level (MIS 6). During the MIS5, the discharge of Mississippi River is thought switched to its present course, ~300 km to the east.

Physiological Indices of Bilingualism: Oral-Motor Coordination and Speech Rate in Bengali-English Speakers

ERIC Educational Resources Information Center

Chakraborty, Rahul; Goffman, Lisa; Smith, Anne

2008-01-01

Purpose: To examine how age of immersion and proficiency in a 2nd language influence speech movement variability and speaking rate in both a 1st language and a 2nd language. Method: A group of 21 Bengali-English bilingual speakers participated. Lip and jaw movements were recorded. For all 21 speakers, lip movement variability was assessed based on…

Screening-Constant-by-Unit-Nuclear-Charge method investigations of high lying (1D2,1S0) ns, nd Rydberg series in the photoionization spectra of the halogen-like ion Kr+

NASA Astrophysics Data System (ADS)

Sakho, I.

2014-01-01

Energy positions and quantum defects of the 4s24p4 (1D2,1S0) ns, nd Rydberg series originating from the 4s24p52P3/2∘ ground state and from the 4s24p52P1/2∘ metastable state of Kr+ are reported. Calculations are performed using the Screening Constant by Unit Nuclear Charge (SCUNC) method. The results obtained are in suitable agreement with recent experimental data from the combined ASTRID merged-beam set up and Fourier Transform Ion Cyclotron Resonance device (Bizau et al., 2011), ALS measurements (Hinojosa et al., 2012), and multi-channel R-matrix eigenphase derivative calculations (McLaughlin and Balance, 2012). In addition, analysis of the 4s24p4(1D2)nd and the 4s24p4(1S0)nd resonances is given via the SCUNC procedure. The excellent results obtained from our work point out that the SCUNC formalism may be used to confirm the results of the analysis from the standard quantum-defect expansion formulas. Eventual errors occurring in the analysis can then be automatically detected and corrected via the SCUNC procedure.

Installation Restoration Program. Remedial Investigation Report. Site 1. Fire Training Area. Volk Field Air National Guard Base, Camp Douglas, WI. Volume 2

DTIC Science & Technology

1990-07-01

trobenzen. 660’ ug/KG Phenacet in 6600 ug/KG 2- Picoline 660’ ug/KG Pronamide 10000 ug/KG 1,2,4, 5-Tetrachlorobenzene 660’ ug/KO 0 Denotes instrument...Phenacetin ND 2- Picoline ND Pronamide ND 1,26,4,5-Tetrachlorobenzene -*ND *EPA has not yet determined detection limits for these compounds E-158 I Pr...ND N-Nitrosopiperidine - ND Pentachlorobenzene ND Pentachloromitrobenzene -*ND Phenacetin ND 2- Picoline ND Pronamide - *ND 1,2,4,5

Micro-Raman spectroscopy of natural and synthetic indigo samples.

PubMed

Vandenabeele, Peter; Moens, Luc

2003-02-01

In this work indigo samples from three different sources are studied by using Raman spectroscopy: the synthetic pigment and pigments from the woad (Isatis tinctoria) and the indigo plant (Indigofera tinctoria). 21 samples were obtained from 8 suppliers; for each sample 5 Raman spectra were recorded and used for further chemometrical analysis. Principal components analysis (PCA) was performed as data reduction method before applying hierarchical cluster analysis. Linear discriminant analysis (LDA) was implemented as a non-hierarchical supervised pattern recognition method to build a classification model. In order to avoid broad-shaped interferences from the fluorescence background, the influence of 1st and 2nd derivatives on the classification was studied by using cross-validation. Although chemically identical, it is shown that Raman spectroscopy in combination with suitable chemometric methods has the potential to discriminate between synthetic and natural indigo samples.

Tunable femtosecond laser based on the Nd3+:BaLaGa 3O 7 disordered crystal

NASA Astrophysics Data System (ADS)

Agnesi, A.; Pirzio, F.; Tartara, L.; Ugolotti, E.; Zhang, H.; Wang, J.; Yu, H.; Petrov, V.

2014-03-01

We demonstrate clear inhomogeneous linewidth broadening for the disordered laser crystal Nd:BaLaGa3O7 (Nd:BLG), which is very promising for the replacement of Nd:glass for ultrafast sources in multiwatt power applications. A Nd:BLG laser oscillator passively mode-locked and pumped by a Ti:sapphire laser generated pulses of 316-fs duration at 1060 nm, whose spectrum completely fills the fluorescence peak at such wavelength. More interestingly, sub-picosecond pulses were smoothly tunable in a 20-nm range, from 1070 to 1090 nm. The shortest pulses achieved were 290 fs long, centered at 1075 nm.

Neodymium cobalt oxide as a chemical sensor

NASA Astrophysics Data System (ADS)

Abdel-Latif, I. A.; Rahman, Mohammed M.; Khan, Sher Bahadar

2018-03-01

Chemical sensing and electrical transport properties of neodymium coblate, NdCoO3, was investigated in this work. It was prepared by using co-precipitation method. Pure neodymium chloride and cobalt chloride were mixing in the presence of sodium hydroxide and the obtained co-precipitated powder was calcined at 850 and 1000 °C. The synthesized composites, as-grown (NdCoO3-I), calcined at 850 °C (NdCoO3-II), and calcined at 1000 °C (NdCoO3-III) were studied in details in terms of their morphological and structural properties. The X-ray analysis confirmed that the synthesized products are well crystalline possessing single phase orthorhombic crystal system of space group Pbnm(62). The crystallite size of NdCoO3-I, NdCoO3-II, and NdCoO3-III is 22, 111, and 338 nm, respectively which reflect that crystallite size is increasing with increase in firing temperature. The DC resistivity was measured as a function of temperature in the temperature range from room temperature up to 200 °C. All NdCoO3 are semiconductor in this range of temperature but showed different activation energy which strongly depends on the crystallite size of the products. The activation energy decreased with increase in crystallite size, 0.798, 0.414 and 0.371 eV for NdCoO3-I, NdCoO3-II, and NdCoO3-III, respectively. Thus resistivity increases with increase in crystallite size of NdCoO3. All NdCoO3 products were tested as chemical sensor for acetone by electrochemical approaches and showed excellent sensitivity. Among the NdCoO3 samples, NdCoO3-III showed the highest sensitivity (3.4722 μAcm-2 mM-1) compared to other compositions and gradually decreased to 3.2407 μAcm-2 mM-1 with decreasing the crystallite size of NdCoO3-II. It is also observed that the sensitivity drastically decreased to 0.76253 μAcm-2 mM-1 in the case of NdCoO3-I. It is introduced an efficient route for the detection of environmental unsafe chemicals by electrochemical approach for the safety of healthcare and environmental fields in broad scales.

Re-exchange of Fe and Cu at the interface in sintered Nd-Fe-B magnets: A method to eliminate Fe precipitation at grain boundaries

NASA Astrophysics Data System (ADS)

Yang, YuQi; Si, HengGang; Yang, Hao; Zhang, Lan; Huang, DongFang; Chen, BaiYi; Xu, Fang; Hu, YongMei; Han, BaoJun

2018-01-01

According to the decoupling hypothesis for magnetic grains, the coercivity in sintered Nd-Fe-B magnets is increased after Cu doping, which is due to the formation of non-magnetic grain boundaries. However, this method partially fails, and ferromagnetic Fe-segregation occurs at the grain boundary. We discovered both experimentally and through calculation that the Fe content at the grain boundaries can be tuned across a wide range by introducing another element of Ag. Segregated Fe at high temperature at the grain boundary re-dissolves into Nd2Fe14B grains during annealing at low temperature. Both configurable and magnetic entropies contribute a large driving force for the formation of nonmagnetic grain boundaries. Almost zero Fe content could be achieved at the grain boundaries of sintered Nd-Fe-B magnet.

The effect of diamond nanoparticles on redox and immune parameters in rats.

PubMed

Niemiec, Tomasz; Szmidt, Maciej; Sawosz, Ewa; Grodzik, Marta; Mitura, Katarzyna

2011-10-01

The objective of the study was to evaluate the effect of nanodiamond (ND) particles manufactured by detonation method (size of grains 2-10 nm) on organism health status. Wistar rats were administrated with diamond nanoparticles colloid by intravenous and intraperitoneal injection. Both routes of administration increased superoxide dismutase (SOD) activity and at the same time decreased activity of glutathione reductase (GR) and glutathione peroxidase (GPx) within erythrocytes. ND did not significantly affect neither total antioxidative state (TAS) nor thiobarbituric acid reactive substances (TBARS) in examined animals blood plasma. This study was also designed to examine the effect of ND on the phagocytosis activity and oxidative burst of innate immune cells. Both intravenous and intraperitoneal administration of ND hydrocolloid decreased the number of the phagocytosing neutrophiles stimulated by E. coli. Independently of the injection method nanodiamond increased the number of cells with stimulated oxidative burst and it suppressed the mechanism of oxygen dependent bacteria elimination.

The Chronology and Petrogenesis of the Mare Basalt Clast from Lunar Meteorite Dhofar 287: Rb-Sr and Sm- Nd Isotopic Studies

NASA Technical Reports Server (NTRS)

Shih, C.-Y.; Nyquist, L. E.; Reese, Y.; Wiesmann, H.; Nazarov, M. A.; Taylor, L. A.

2002-01-01

The Sm-Nd isochron for lunar mare basalt meteorite Dhofar 287A yields T = 3.46 +/- 0.03 Ga and Nd = 0.6 +/- 0.3. Its Rb-Sr isotopic system is severely altered. The basalt is unique, probably coming from an enriched mantle source. Additional information is contained in the original extended abstract.

Flux pinning properties of GdBCO bulk through the infiltration and growth process

NASA Astrophysics Data System (ADS)

Zhang, Y. F.; Wang, J. J.; Zhang, X. J.; Pan, C. Y.; Zhou, W. L.; Xu, Y.; Liu, Y. S.; Izumi, M.

2017-06-01

REBa2Cu3O7-δ(RE123 or REBCO, RE=rare earth elements, Gd, Y, Nd, etc.) bulk high temperature superconductors (HTS) have been used in lots of aspects, such as in magnetic levitation, et al., owing to the performance of high magnetic flux trapping. GdBCO superconductor bulk with 25 mm diameter has been successfully fabricated by top-seeded infiltration and growth (TSIG) method. We chose YBa2Cu3O7-δ (Y123) particles as the liquid source, which provide enough liquid sources during the growth and encourage the growth along a-b plane of GdBCO bulk. Then the existence of Y123 liquid source partly decreases the effect of the sub-grain boundaries in a-growth sectors and improves the properties of GdBCO bulk. The shape of the trapped field is close to circle. The critical current density of C2 and B2 (JC ) enhances. The superconducting transition temperature (TC ) is around 94.5K in the different position and keeps the superconducting properties. It is the important experimental data for the engineering applications of the superconductor bulk.

Effect of neodymium substitutions on electromagnetic properties in low temperature sintered NiCuZn ferrite

NASA Astrophysics Data System (ADS)

Wu, C. P.; Tung, M. J.; Ko, W. S.; Wang, Y. P.; Tong, S. Y.; Yang, M. D.

2015-11-01

Nd3+ ions substituted Ni0.37Cu0.14Zn0.52Fe2O4 (Nd3+ ions content=0, 0.01, 0.04, 0.6, 1.5 wt%) were prepared by the usual standard ceramic method at 1030 °C sintering temperature, and the composition dependence of the physical and magnetic properties has been investigated. SEM micrographs and EDX analysis revealed that it is no obvious impurities up to Nd3+ ions content wt%=0.04. For higher Nd3+ ions content samples (0.6 and 1.5 wt%), there are two kind of impurities Cu-rich and Nd-rich iron oxide phase. The saturation magnetization of the 0.01 wt% Nd3+ions content sample is higher as result of that the A-B sites distance and YK-angles are shorter and smaller. The saturation magnetization of 0.04-1.5 wt% Nd3+ ion content sample are reduced, since the total magnetic moments of the AB site are decreased. For the 0.6 wt% sample, the Curie temperature increasing is as result of the Cu-rich iron oxide separating out. The maximum enhancements of permeability μ‧ are improved to 11.2% (0.04 wt%) and 29.2% (0.6 wt%) at the 6.7 and 13.8 MHz, respectively. However, it is notice that small amount substitutions of Nd3+ increase the high frequency electromagnetic characteristics, can be applied to NFC technology and WPT technologies.

Efficient upconversion emission in Ho3+/Nd3+ co-doped oxyfluorosilicate glasses

NASA Astrophysics Data System (ADS)

Devarajulu, G.; Raju, B. Deva Prasad

2018-04-01

We report on an efficient Ho3+ and Ho3+/Nd3+ co-doped oxyfluorosilicate glasses upon excitation with an 808 nm laser diode. The detailed fluorescence have been studied under this excitation source and energy transfer mechanisms in Ho3+/Nd3+ co-doped oxyfluorosilicate glasses. The upconversion peaks at 486, 547 and 596 nm were observed in Nd3+/Ho3+ co-doped sample. The intensity of upconversion emission transitions in Ho3+ depends on the neodymium codopent concentration. These results indicate that Nd3+ ions can be potentially used as sensitizer for Ho3+ ions to stimulate the intense upconversion emission. The energy transfer mechanism between Nd3+ and Ho3+ was analyzed pursuant to the absorption spectra, upconversion spectra and the energy level structures of Nd3+ and Ho3+ ions have been briefly discussed.

Polyamidoamine-Decorated Nanodiamonds as a Hybrid Gene Delivery Vector and siRNA Structural Characterization at the Charged Interfaces.

PubMed

Lim, Dae Gon; Rajasekaran, Nirmal; Lee, Dukhee; Kim, Nam Ah; Jung, Hun Soon; Hong, Sungyoul; Shin, Young Kee; Kang, Eunah; Jeong, Seong Hoon

2017-09-20

Nanodiamonds have been discovered as a new exogenous material source in biomedical applications. As a new potent form of nanodiamond (ND), polyamidoamine-decorated nanodiamonds (PAMAM-NDs) were prepared for E7 or E6 oncoprotein-suppressing siRNA gene delivery for high risk human papillomavirus-induced cervical cancer, such as types 16 and 18. It is critical to understand the physicochemical properties of siRNA complexes immobilized on cationic solid ND surfaces in the aspect of biomolecular structural and conformational changes, as the new inert carbon material can be extended into the application of a gene delivery vector. A spectral study of siRNA/PAMAM-ND complexes using differential scanning calorimetry and circular dichroism spectroscopy proved that the hydrogen bonding and electrostatic interactions between siRNA and PAMAM-NDs decreased endothermic heat capacity. Moreover, siRNA/PAMAM-ND complexes showed low cell cytotoxicity and significant suppressing effects for forward target E6 and E7 oncogenic genes, proving functional and therapeutic efficacy. The cellular uptake of siRNA/PAMAM-ND complexes at 8 h was visualized by macropinocytes and direct endosomal escape of the siRNA/PAMAM-ND complexes. It is presumed that PAMAM-NDs provided a buffering cushion to adjust the pH and hard mechanical stress to escape endosomes. siRNA/PAMAM-ND complexes provide a potential organic/inorganic hybrid material source for gene delivery carriers.

M-H characteristics and demagnetization resistance of samarium-cobalt permanent magnets to 300 C

NASA Technical Reports Server (NTRS)

Niedra, Janis M.

1992-01-01

The influence of temperature on the M-H demagnetization characteristics of permanent magnets is important information for the full utilization of the capabilities of samarium-cobalt magnets at high temperatures in demagnetization-resistant permanent magnet devices. In high temperature space power converters, such as free-piston Stirling engine driven linear alternators, magnet demagnetization can occur as a long-term consequence of thermal agitation of domains and of metallurgical change, and also as an immediate consequence of too large an applied field. Investigated here is the short-term demagnetization resistance to applied fields derived from basic M-H data. This quasistatic demagnetization data was obtained for commercial, high-intrinsic-coercivity, Sm2Co17-type magnets from 5 sources, in the temperature range 23 to 300 C. An electromagnet driven, electronic hysteresigraph was used to test the 1-cm cubic samples. The observed variation of the 2nd quadrant M-H characteristics was a typical rapid loss of M-coercivity and a relatively lesser loss of remanence with increasing temperature. The 2nd quadrant M-H curve knee point is used to define the limits of operation safe against irreversible demagnetization due to an excessive bucking field for a given flux density swing at temperature. Such safe operating area plots are shown to differentiate the high temperature capabilities of the samples from different sources. For most of the samples, their 2nd quadrant M-H loop squareness increased with temperature, reaching a peak or a plateau above 250 C.

Effect of ammonium carbonate to metal ions molar ratio on synthesis and sintering of Nd:YAG nanopowders

NASA Astrophysics Data System (ADS)

Liu, Qiang; Chen, Cong; Dai, Jiawei; Hu, Zewang; Chen, Haohong; Li, Jiang

2018-06-01

Using the nanopowders synthesized by a reverse co-precipitation method, neodymium doped yttrium aluminum garnet (Nd:YAG) transparent ceramics were fabricated by vacuum sintering method. The influence of ammonium carbonate to metal ions (NH4HCO3/M3+) molar ratio (R value) on the properties of Nd:YAG precursors and powders, as well as the densification, microstructure, and transmittance of the resultant ceramics was systematically investigated. The results show that the precursors have similar compositions and the calcined powders have pure Y3Al5O12 (YAG) phase. However, the R value is closely related to the morphologies of the precursors and powders. It is found that the powder with R = 3.0 has strongest agglomeration and the powders with R = 3.2-4.0 show better dispersity. Using these powders as starting materials, the corresponding ceramics were sintered at 1720 °C for 20 h in vacuum. As a result, the ceramic with R = 3.2 obtains the best transmittance of about 72% at the wavelength of 1064 nm. The grain growth exponent and activation energy of the Nd:YAG ceramics fabricated from the powder with R = 3.2 were also studied.

Design of a new electron cyclotron resonance ion source at Oshima National College of Maritime Technology

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

Asaji, T., E-mail: asaji@oshima-k.ac.jp; Hirabara, N.; Izumihara, T.

A new electron cyclotron resonance ion/plasma source has been designed and will be built at Oshima National College of Maritime Technology by early 2014. We have developed an ion source that allows the control of the plasma parameters over a wide range of electron temperatures for material research. A minimum-B magnetic field composed of axial mirror fields and radial cusp fields was designed using mainly Nd-Fe-B permanent magnets. The axial magnetic field can be varied by three solenoid coils. The apparatus has 2.45 GHz magnetron and 2.5–6.0 GHz solid-state microwave sources.

Gd Ba Cu O bulk superconductors fabricated by a seeded infiltration growth technique under reduced oxygen partial pressure

NASA Astrophysics Data System (ADS)

Iida, K.; Babu, N. H.; Shi, Y. H.; Cardwell, D. A.; Murakami, M.

2006-06-01

Single-grain Gd-Ba-Cu-O (GdBCO) bulk superconductors have been grown by a seeded infiltration and growth (SIG) technique under a 1% O2+N2 atmosphere using a generic MgO-doped Nd-Ba-Cu-O (MgO-NdBCO) seed placed on the sample surface at room temperature (the so-called the cold-seeding method). Partial melting of the MgO-NdBCO seeds fabricated in air under notionally identical thermal processing conditions, however, limited the reliability of this bulk GdBCO single-grain process. The observed seed decomposition is attributed to the dependence of the peritectic temperature Tp of MgO-doped Nd1+xBa2-xCu3Oy solid solution (MgO-doped Nd-123ss, where ss indicates solid solution) compounds on both oxygen partial pressure during the melt process and the level of solid solution (x). The peritectic decomposition temperature of MgO-doped Nd-123ss, with x ranging from 0 to 0.5 under p(O2) = 1.00 atm, was observed to remain constant at 1120 °C. Tp was observed to decrease linearly as a function of solid solution level, on the other hand, under oxygen partial pressures of both p(O2) = 0.21 and 0.01 atm. Based on these results, MgO-doped NdBCO seed crystals should be grown under reduced oxygen partial pressure in order to obtain a stable MgO-doped NdBCO seed crystal suitable for cold-seeding processes of large-grain (RE)BCO bulk superconductors (where RE is a rare earth element).

Interactive Visualization and Analysis of Geospatial Data Sets - TrikeND-iGlobe

NASA Astrophysics Data System (ADS)

Rosebrock, Uwe; Hogan, Patrick; Chandola, Varun

2013-04-01

The visualization of scientific datasets is becoming an ever-increasing challenge as advances in computing technologies have enabled scientists to build high resolution climate models that have produced petabytes of climate data. To interrogate and analyze these large datasets in real-time is a task that pushes the boundaries of computing hardware and software. But integration of climate datasets with geospatial data requires considerable amount of effort and close familiarity of various data formats and projection systems, which has prevented widespread utilization outside of climate community. TrikeND-iGlobe is a sophisticated software tool that bridges this gap, allows easy integration of climate datasets with geospatial datasets and provides sophisticated visualization and analysis capabilities. The objective for TrikeND-iGlobe is the continued building of an open source 4D virtual globe application using NASA World Wind technology that integrates analysis of climate model outputs with remote sensing observations as well as demographic and environmental data sets. This will facilitate a better understanding of global and regional phenomenon, and the impact analysis of climate extreme events. The critical aim is real-time interactive interrogation. At the data centric level the primary aim is to enable the user to interact with the data in real-time for the purpose of analysis - locally or remotely. TrikeND-iGlobe provides the basis for the incorporation of modular tools that provide extended interactions with the data, including sub-setting, aggregation, re-shaping, time series analysis methods and animation to produce publication-quality imagery. TrikeND-iGlobe may be run locally or can be accessed via a web interface supported by high-performance visualization compute nodes placed close to the data. It supports visualizing heterogeneous data formats: traditional geospatial datasets along with scientific data sets with geographic coordinates (NetCDF, HDF, etc.). It also supports multiple data access mechanisms, including HTTP, FTP, WMS, WCS, and Thredds Data Server (for NetCDF data and for scientific data, TrikeND-iGlobe supports various visualization capabilities, including animations, vector field visualization, etc. TrikeND-iGlobe is a collaborative open-source project, contributors include NASA (ARC-PX), ORNL (Oakridge National Laboratories), Unidata, Kansas University, CSIRO CMAR Australia and Geoscience Australia.

Electronic polarizability, optical basicity and interaction parameter for Nd2O3 doped lithium-zinc-phosphate glasses

NASA Astrophysics Data System (ADS)

Algradee, M. A.; Sultan, M.; Samir, O. M.; Alwany, A. Elwhab B.

2017-08-01

The Nd3+-doped lithium-zinc-phosphate glasses were prepared by means of conventional melt quenching method. X-ray diffraction results confirmed the glassy nature of the studied glasses. The physical parameters such as the density, molar volume, ion concentration, polaron radius, inter-ionic distance, field strength and oxygen packing density were calculated using different formulae. The transmittance and reflectance spectra of glasses were recorded in the wavelength range 190-1200 nm. The values of optical band gap and Urbach energy were determined based on Mott-Davis model. The refractive indices for the studied glasses were evaluated from optical band gap values using different methods. The average electronic polarizability of the oxide ions, optical basicity and an interaction parameter were investigated from the calculated values of the refractive index and the optical band gap for the studied glasses. The variations in the different physical and optical properties of glasses with Nd2O3 content were discussed in terms of different parameters such as non-bridging oxygen and different concentrations of Nd cation in glass system.

Treatment of deep underlying reticular veins by Nd:Yag laser and IPL source.

PubMed

Colaiuda, S; Colaiuda, F; Gasparotti, M

2000-10-01

The purpose of this paper is to estimate the efficacy of Nd:Yag laser and IPL combined action for the treatment of deep (up to 5 mm) and large (up to 3 mm in diameter) reticular varicosity of the lower extremity. A group of 38 subjects (2 male and 36 female) aged from 34 to 65 years were treated for deep reticular varicosity of the legs. All patients underwent various clinical analyses in order to evaluate and exclude pre-existing cardiovascular pathology, coagulation disorders as well as pathology due to saphena incontinence. Also, for the first three months they underwent ambulatory specialistic treatments at 21-days intertreatment interval. A reduction of venous network of 80-90% after 2 treatment sessions with Nd:Yag laser was obtained in 84% of subjects. Successive 3 treatment sessions with IPL have achieved complete vanishing of the treated venous network in 36 patients (95%). A combined action of Nd:Yag laser and IPL has demonstrated its particular efficacy in non-invasive treatment of deep and extensive reticolar varicosity of the lower extremity, considering also that it is well tolerated by patients and applicable in each single case on out patient basis.

The isotopic and chemical evolution of Mount St. Helens

USGS Publications Warehouse

Halliday, A.N.; Fallick, A.E.; Dickin, A.P.; Mackenzie, A.B.; Stephens, W.E.; Hildreth, W.

1983-01-01

Isotopic and major and trace element analysis of nine samples of eruptive products spanning the history of the Mt. St. Helens volcano suggest three different episodes; (1) 40,000-2500 years ago: eruptions of dacite with ??{lunate}Nd = +5, ??{lunate}Sr = -10, variable ??18O, 206Pb/204Pb ??? 18.76, Ca/Sr ??? 60, Rb/Ba ??? 0.1, La/Yb ??? 18, (2) 2500-1000 years ago: eruptions of basalt, andesite and dacite with ??{lunate}Nd = +4 to +8, ??{lunate}Sr = -7 to -22, variable ??18O (thought to represent melting of differing mantle-crust reservoirs), 206Pb/204Pb = 18.81-18.87, variable Ca/Sr, Rb/Ba, La/Yb and high Zr, (3) 1000 years ago to present day: eruptions of andesite and dacite with ??{lunate}Nd = +6, ??{lunate}Sr = -13, ??18O ???6???, variable 206Pb/204Pb, Ca/Sr ??? 77, Rb/Ba = 0.1, La/Yb ??? 11. None of the products exhibit Eu anomalies and all are LREE enriched. There is a strong correlation between 87Sr/86Sr and differentiation indices. These data are interpreted in terms of a mantle heat source melting young crust bearing zircon and garnet, but not feldspar, followed by intrusion of this crustal reservoir by mantle-derived magma which caused further crustal melting and contaminated the crustal magma system with mafic components. Since 1000 years ago all the eruptions have been from the same reservoir which has displayed a much more gradual re-equilibration of Pb isotopic compositions than other components suggesting that Pb is being transported via a fluid phase. The Nd and Sr isotopic compositions lie along the mantle array and suggest that the mantle underneath Mt. St. Helens is not as depleted as MORB sources. There is no indication of seawater involvement in the source region. ?? 1983.

The Atlantic Meridional Overturning Circulation over time: a Nd isotope perspective

NASA Astrophysics Data System (ADS)

Goldstein, S. L.; Pena, L. D.; Yehudai, M.; Seguí, M. J.; Kim, J.; Knudson, K. P.; Basak, C.

2017-12-01

The Atlantic Meridional Overturning Circulation (AMOC) is a major means for distributing heat between the tropics and the high latitudes, and thus its temporal variability has major impacts on ice age cycles. We present a summary of work in-progress to generate north-south profiles of the AMOC from the North Atlantic to the Southern Ocean, at various time slices over the past 2 Ma, based on Nd isotopes in Fe-Mn oxide encrusted foraminifera and fish debris. Our sites show a consistent north-south gradient in the North Atlantic source water (NSW) signal strength throughout, providing strong evidence that the data represent the fluctuations of the AMOC. The North Atlantic data show strong evidence that the eNd of the NSW end-member remained similar to today through this time interval (Kim et al. this meeting). We have identified 5 modes of the AMOC circulation. The most common ones are the (1) "interglacial norm" where the NSW signal remains strong into the South Atlantic similar to the present-day, and the (2) "glacial norm" where moderate southern source water (SSW) signals extend into the deep North Atlantic. Less common are the (3) "weak AMOC" mode, typical of Heinrich events, the Mid-Pleistocene Transition (MPT), and MIS 10,16, where even the deep North Atlantic shows a strong SSW signal, and its counterpart the (4) "ultra-strong AMOC", in MIS 9, 11, 19, 21 and 25, when the NSW signal is unusually strong south of the equator. Finally, during the (5) "pre-MPT" mode, in MIS 26 and 27, uniquely low Nd isotope ratios in the North Atlantic signals major input of Nd from the Canadian Shield directly preceding the MPT AMOC crisis (Pena and Goldstein, Science 2014), reflecting events there that likely triggered it. Overall we expect that the AMOC profiles will be useful as a means to directly relate climate to concurrent ocean circulation through time.

Laser-produced plasma EUV source using a colloidal microjet target containing tin dioxide nanoparticles

NASA Astrophysics Data System (ADS)

Higashiguchi, Takeshi; Dojyo, Naoto; Sasaki, Wataru; Kubodera, Shoichi

2006-10-01

We realized a low-debris laser-produced plasma extreme ultraviolet (EUV) source by use of a colloidal microjet target, which contained low-concentration (6 wt%) tin-dioxide nanoparticles. An Nd:YAG laser was used to produce a plasma at the intensity on the order of 10^11 W/cm^2. The use of low concentration nanoparticles in a microjet target with a diameter of 50 μm regulated the neutral debris emission from a target, which was monitored by a silicon witness plate placed 30 cm apart from the source in a vacuum chamber. No XPS signals of tin and/or oxygen atoms were observed on the plate after ten thousand laser exposures. The low concentration nature of the target was compensated and the conversion efficiency (CE) was improved by introducing double pulses of two Nd:YAG lasers operated at 532 and 1064 nm as a result of controlling the micro-plasma characteristics. The EUV CE reached its maximum of 1.2% at the delay time of approximately 100 ns with the main laser intensiy of 2 x10^11 W/cm^2. The CE value was comparable to that of a tin bulk target, which, however, produced a significant amount of neutral debris.

Effect of magnetic soft phase on the magnetic properties of bulk anisotropic Nd2Fe14B/α-Fe nanocomposite permanent magnets

NASA Astrophysics Data System (ADS)

Li, Yuqing; Yue, Ming; Zhao, Guoping; Zhang, Hongguo

2018-01-01

The effects of soft phase with different particle sizes and distributions on the Nd2Fe14B/α-Fe nanocomposite magnets have been studied by the micro-magnetism simulation. The calculated results show that smaller and/or scattered distribution of soft phase can benefit to the coercivity (H ci) of the nanocomposite magnets. The magnetization moment evolution during magnetic reversal is systematically analyzed. On the other hand, magnetic properties of anisotropic Nd-Fe-B/α-Fe nanocomposite magnets prepared by hot pressing and hot deformation methods also provide evidences for the calculated results.

Nanocrystalline NiNd0.01Fe1.99O4 as a gas sensor

NASA Astrophysics Data System (ADS)

Shinde, Tukaram J.; Gadkari, Ashok B.; Jadhav, Sarjerao R.; Kumar, Surender; Dalawai, Sanjeev P.; Vasambekar, Pramod N.

2015-06-01

Nanocrystalline NiNd0.01Fe1.99O4 has been synthesized by oxalate co-precipitation method and was characterized by X-ray diffraction technique. X-ray diffraction analysis confirms the formation of single phase cubic spinel structure. Crystallite size of the ferrite lies in the nano-particle range. The gas sensing properties of nanocrystalline ferrite were studied for gases like Cl2, LPG and C2H5OH. It was observed that NiNd0.01Fe1.99O4 is more sensitive towards chlorine followed by LPG at an operating temperature 277 °C compared to ethanol.

Investigations of shot reproducibility for the SMP diode at 4.5 MV.

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

Bennett, Nichelle; Crain, Marlon D.; Droemer, Darryl W.

In experiments conducted on the RITS-6 accelerator, the SMP diode exhibits sig- ni cant shot-to-shot variability. Speci cally, for identical hardware operated at the same voltage, some shots exhibit a catastrophic drop in diode impedance. A study is underway to identify sources of shot-to-shot variations which correlate with diode impedance collapse. To remove knob emission as a source, only data from a shot series conducted with a 4.5-MV peak voltage are considered. The scope of this report is limited to sources of variability which occur away from the diode, such as power ow emission and trajectory changes, variations in pulsedmore » power, dustbin and transmission line alignment, and di erent knob shapes. We nd no changes in the transmission line hardware, alignment, or hardware preparation methods which correlate with impedance collapse. However, in classifying good versus poor shots, we nd that there is not a continuous spectrum of diode impedance behavior but that the good and poor shots can be grouped into two distinct impedance pro les. This result forms the basis of a follow-on study focusing on the variability resulting from diode physics. 3« less

Second-Order Sensitivity Analysis of Uncollided Particle Contributions to Radiation Detector Responses

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

Cacuci, Dan G.; Favorite, Jeffrey A.

This work presents an application of Cacuci’s Second-Order Adjoint Sensitivity Analysis Methodology (2nd-ASAM) to the simplified Boltzmann equation that models the transport of uncollided particles through a medium to compute efficiently and exactly all of the first- and second-order derivatives (sensitivities) of a detector’s response with respect to the system’s isotopic number densities, microscopic cross sections, source emission rates, and detector response function. The off-the-shelf PARTISN multigroup discrete ordinates code is employed to solve the equations underlying the 2nd-ASAM. The accuracy of the results produced using PARTISN is verified by using the results of three test configurations: (1) a homogeneousmore » sphere, for which the response is the exactly known total uncollided leakage, (2) a multiregion two-dimensional (r-z) cylinder, and (3) a two-region sphere for which the response is a reaction rate. For the homogeneous sphere, results for the total leakage as well as for the respective first- and second-order sensitivities are in excellent agreement with the exact benchmark values. For the nonanalytic problems, the results obtained by applying the 2nd-ASAM to compute sensitivities are in excellent agreement with central-difference estimates. The efficiency of the 2nd-ASAM is underscored by the fact that, for the cylinder, only 12 adjoint PARTISN computations were required by the 2nd-ASAM to compute all of the benchmark’s 18 first-order sensitivities and 224 second-order sensitivities, in contrast to the 877 PARTISN calculations needed to compute the respective sensitivities using central finite differences, and this number does not include the additional calculations that were required to find appropriate values of the perturbations to use for the central differences.« less

Second-Order Sensitivity Analysis of Uncollided Particle Contributions to Radiation Detector Responses

DOE PAGES

Cacuci, Dan G.; Favorite, Jeffrey A.

2018-04-06

This work presents an application of Cacuci’s Second-Order Adjoint Sensitivity Analysis Methodology (2nd-ASAM) to the simplified Boltzmann equation that models the transport of uncollided particles through a medium to compute efficiently and exactly all of the first- and second-order derivatives (sensitivities) of a detector’s response with respect to the system’s isotopic number densities, microscopic cross sections, source emission rates, and detector response function. The off-the-shelf PARTISN multigroup discrete ordinates code is employed to solve the equations underlying the 2nd-ASAM. The accuracy of the results produced using PARTISN is verified by using the results of three test configurations: (1) a homogeneousmore » sphere, for which the response is the exactly known total uncollided leakage, (2) a multiregion two-dimensional (r-z) cylinder, and (3) a two-region sphere for which the response is a reaction rate. For the homogeneous sphere, results for the total leakage as well as for the respective first- and second-order sensitivities are in excellent agreement with the exact benchmark values. For the nonanalytic problems, the results obtained by applying the 2nd-ASAM to compute sensitivities are in excellent agreement with central-difference estimates. The efficiency of the 2nd-ASAM is underscored by the fact that, for the cylinder, only 12 adjoint PARTISN computations were required by the 2nd-ASAM to compute all of the benchmark’s 18 first-order sensitivities and 224 second-order sensitivities, in contrast to the 877 PARTISN calculations needed to compute the respective sensitivities using central finite differences, and this number does not include the additional calculations that were required to find appropriate values of the perturbations to use for the central differences.« less

Nd:YAG laser therapy in bronchogenic tumors

NASA Astrophysics Data System (ADS)

Benov, Emil; Kostadinov, D.; Mitchev, K.; Vlasov, V.

1993-03-01

In 2 years 53 patients with tumors of the tracheobronchial tree have been treated by photocoagulation therapy. Forty cases of them were with different types of cancer and 13 cases with benign lesions of the trachea or bronchi. As a laser source we used an Nd:YAG laser, MBB, Germany. At first the tumor was irradiated with a power of 25 - 30 W, following power up to 90 W. The median energy dose was 3,500 J/sq cm for each patient. The treatment was executed under local anesthesia with a rigid or flexible bronchoscope. In all of the cases with benign tumors we obtained a stable positive effect. In 15 cases of carcinoma we attained a recanalization and restoration of the ventilation to the treated area -- 37.5%. The only complication due to the procedure was the death of one patient with a tracheal cancer and myasthenia gravis. Photocoagulation therapy is an effective method for benign tumors. In cases with carcinoma this therapy is used with palliative purpose -- recanalization of the bronchus. Laser endobronchial therapy shows an immediate positive effect in the treatment of airway obstruction.

Spectral lines and characteristic of temporal variations in photoionized plasmas induced with laser-produced plasma extreme ultraviolet source

NASA Astrophysics Data System (ADS)

Saber, I.; Bartnik, A.; Wachulak, P.; Skrzeczanowski, W.; Jarocki, R.; Fiedorowicz, H.

2017-11-01

Spectral lines for Kr/Ne/H2 photoionized plasma in the ultraviolet and visible (UV/Vis) wavelength ranges have been created using a laser-produced plasma (LPP) EUV source. The source is based on a double-stream gas puff target irradiated with a commercial Nd:YAG laser. The laser pulses were focused onto a gas stream, injected into a vacuum chamber synchronously with the EUV pulses. Spectral lines from photoionization in neutral Kr/Ne/H2 and up to few charged states were observed. The intense emission lines were associated with the Kr transition lines. Experimental and theoretical investigations on intensity variations for some ionic lines are presented. A decrease in the intensity with the delay time between the laser pulse and the spectrum acquisition was revealed. Electron temperature and electron density in the photoionized plasma have been estimated from the characteristic emission lines. Temperature was obtained using Boltzmann plot method, assuming that the population density of atoms and ions are considered in a local thermodynamic equilibrium (LTE). Electron density was calculated from the Stark broadening profile. The temporal evaluation of the plasma and the way of optimizing the radiation intensity of LPP EUV sources is discussed.

Kinetic analysis of IMP split dose method for two consecutive measurement of cerebral blood flow

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

Nishizawa, S.; Yonekura, Y.; Tanaka, F.

1994-05-01

The split dose method for two consecutive measurements of cerebral blood flow (CBF) with I-123 IMP seems to offer a great merit to the SPECT study of the brain. However, because of complexity of the dynamics of IMP, it is not clear if microsphere (MS) model permits a estimation of CBF for the 2nd dose. We applied kinetic (KN) analysis based on 2 compartment model to the dynamic SPECT scan data, and compared the results with those obtained by MS model. Dynamic SPECT (1-min scans for 50 min) was performed using 3-head SPECT camera in 5 patients to test themore » reproducibility of measured CBF and in 9 patients to test the vascular response to acetazolamide (ACZ). Two doses of IMP (111 MBq each) were injected at the time of, and 25 min after, the scan initiation. ACZ (1g) was administered at 13 min. Arterial blood samples were drawn manually during the scan and an octanol extracted input function was obtained. Dynamic scan data for 22 min was used for CBF by KN analysis (K1), and 4-min scan data at 5 min for CBF by MS model (Km), for each dose. For 2nd CBF by MS model, simple subtraction of brain activity due to the I st dose was done using 4-min scan data just prior to the 2nd dose. Reproducibility of measured CBF by KN analysis was excellent (r=0.949, 1st K1=39.2{plus_minus}5.6 and 2nd K1=38.5{plus_minus}6.6 ml/l00g/min: mean{plus_minus}SD). Vascular response to ACZ was good (1st K1=42.4{plus_minus}7.8 to 2nd K1=67.9{plus_minus}10.0) in areas without ischemia, but poor (1st K1=41.1{plus_minus}8.5 to 2nd K1=46.1{plus_minus}11.1) in ischemic areas. Compared to KN analysis, MS model underestimated 3.5% for the 1st CBF measurement and 12.8% for the 2nd. However, excellent correlation was observed not only between 1st K1 and Km (r=0.993, slope=0.920) but between 2nd K1 and Km (r=0.994, slope=0.814), and the results permitted a reasonable correction for Km.« less

OPO performance with a long pulse length, single frequency Nd:YAG laser pump. [Optical Parametric Oscillators

NASA Technical Reports Server (NTRS)

Kozlovsky, W. J.; Gustafson, E. K.; Eckardt, R. C.; Byer, R. L.

1988-01-01

With the advent of new nonlinear materials and single-frequency pump sources, there is renewed interest in optical parametric oscillators (OPOs). A single-mode diode-laser-pumped monolithic Nd:YAG nonplanar ring laser that is both amplified and frequency doubled is used to pump a monolithic MgO:LiNbO3 pulsed singly resonant OPO. The OPO signal output was temperature tuned from 834 to 958 nm, producing an idler tuning from 1.47 to 1.2 microns. Efforts toward a CW all-solid-state doubly resonant OPO are also described.

Photocatalytic Water Splitting for O2 Production under Visible Light Irradiation Using NdVO4-V2O5 Hybrid Powders

PubMed Central

Chiang, Tzu Hsuan; Chen, Tso-Ming

2017-01-01

The study investigated photocatalytic water splitting for O2 production under visible light irradiation using neodymium vanadium oxide (NdVO4) and vanadium oxide (V2O5) hybrid powders. The results in a sacrificial agent of 0.01 M AgNO3 solution were obtained, and the highest photocatalytic O2 evolution was 2.63 μmol/h, when the hybrid powders were prepared by mixing Nd and V at a volume ratio of 1:3 at a calcination temperature of 350 °C for 1 h. The hybrid powders were synthesized by neodymium nitrate and ammonium metavanadate using the glycothermal method in ethylene glycol at 120 °C for 1 h. The hybrid powders consisted of two shapes, NdVO4 nanoparticles and the cylindrical V2O5 particles, and they possessed the ability for photocatalytic oxygen (O2) evolution during irradiation with visible light. The band gaps and structures of the hybrid powders were analyzed using UV-visible spectroscopy and transmission electron microscopy. PMID:28772692

Isotopic evolution of Mauna Kea volcano: Results from the initial phase of the Hawaii Scientific Drilling Project

USGS Publications Warehouse

Lassiter, J.C.; DePaolo, D.J.; Tatsumoto, M.

1996-01-01

We have examined the Sr, Nd, and Pb isotopic compositions of Mauna Kea lavas recovered by the first drilling phase of the Hawaii Scientific Drilling Project. These lavas, which range in age from ???200 to 400 ka, provide a detailed record of chemical and isotopic changes in basalt composition during the shied/postshield transition and extend our record of Mauna Kea volcanism to a late-shield period roughly equivalent to the last ???100 ka of Mauna Loa activity. Stratigraphic variations in isotopic composition reveal a gradual shift over time toward a more depleted source composition (e.g., higher 143Nd/144Nd, lower 87Sr/86Sr, and lower 3He/4He). This gradual evolution is in sharp contrast with the abrupt appearance of alkalic lavas at ???240 ka recorded by the upper 50 m of Mauna Kea lavas from the core. Intercalated tholeiitic and alkalic lavas from the uppermost Mauna Kea section are isotopically indistinguishable. Combined with major element evidence (e.g., decreasing SiO2 and increasing FeO) that the depth of melt segregation increased during the transition from tholeiitic to alkalic volcanism, the isotopic similarity of tholeiitic and alkalic lavas argues against significant lithosphere involvement during melt generation. Instead, the depleted isotopic signatures found in late shield-stage lavas are best explained by increasing the proportion of melt generated from a depleted upper mantle component entrained and heated by the rising central plume. Direct comparison of Mauna Kea and Mauna Loa lavas erupted at equivalent stages in these volcanoes' life cycles reveals persistent chemical and isotopic differences independent of the temporal evolution of each volcano. The oldest lavas recovered from the drillcore are similar to modern Kilauea lavas, but are distinct from Mauna Loa lavas. Mauna Kea lavas have higher 143Nd/144Nd and 206Pb/204Pb and lower 87Sr/86Sr. Higher concentrations of incompatible trace elements in primary magmas, lower SiO2, and higher FeO also indicate that Mauna Kea lavas formed through smaller degrees of partial melting at greater depth than Mauna Loa lavas. These chemical and isotopic differences are consistently found between volcanoes along the western "Loa" and eastern "Kea" trends and reflect large-scale variations in source composition and melting environment. We propose a simple model of a radially zoned plume centered beneath the Loa trend. Loa trend lavas generated from the hot plume axis reflect high degrees of partial melting from a source containing a mixture of enriched plume-source material and entrained lower mantle. Kea trend lavas, in contrast, are generated from the cooler, peripheral portions of the plume, record lower degrees of partial melting, and tap a source containing a greater proportion of depleted upper mantle.

Relevance of Videogames in the Learning and Development of Young Children

ERIC Educational Resources Information Center

Zhao, Zhuxuan; Linaza-Iglesias, José L.

2015-01-01

Introduction: The study was carried out with children of 2nd, 4th and 6th grades of elementary school in order to explore what and how will children learn from a completely new videogame. Method: We organized children from 2nd, 4th and 6th grades of elemental school, giving them chance to play a freshly released videogame by that time. We formed…

Ore genesis dating: implication of Sm-Nd method using sulfide minerals for mafic-ultramafic layered intrusions of Fennoscandian Shield

NASA Astrophysics Data System (ADS)

Serov, Pavel; Bayanova, Tamara; Steshenko, Ekaterina; Ekimova, Nadezhda

2015-04-01

The main method of dating the ore process was the Re-Os method of sulfides (Luck, Allegre, 1983; Walker et. al., 1991). However, studies of Re-Os systematics of sulfide minerals do not always give the correct ages and showing the disturbances of the Re-Os systematics. At the same time, Sm-Nd age of sulfides in good agreement with the U-Pb dating on zircon and baddeleyite and suggests that the Sm-Nd system of sulfides is more resistant to secondary alteration processes. Our studies have shown that along with rock-forming, ore minerals (sulfides) can be used to determine the ore genesis time of industrially important geological sites, since exactly with the sulfides the industry Pt-Pd mineralization is closely connected. In to Sm-Nd measurements steadily introduce new minerals-geochronometers (i.e. titanite, burbancite, eudialite etc.). Of these, sulfides of PGE-bearing layered intrusions are quite important in terms of dating the process of ore origin. Studying the REE distribution in the sulfides of MOR hydrothermal sources has shown possible REE presence in the sulfide lattice (Rimskaya-Korsakova et. al., 2003). These are difficult to carry out because the concentrations of Sm and Nd isotopes in sulfides are much lower than those in chondrites (Rimskaya-Korsakova et. al., 2003). In (Kong et. al., 2000) sulfides from two metamorphosed chondrites were studied by instrumental neutron activation analysis (INAA) and ion probe. As shown, the level of REE in the sulfide phase determined by the ion probe is quite similar to that obtained by INAA. Although the concentrations of REE in the enstatite and the Fe, Si, Cr-rich inclusions are comparable to those in sulfide, estimates based on mass balance calculations show that the silicate inclusions would not noticeably contribute to the REE budget in sulfides (Kong et. al., 2000). For the first time in Russian geochemistry laboratories using sulfide and rock-forming minerals and WR in Sm-Nd method have been dated impregnated and brecciform ores of the following objects - Pilguyarvi Cu-Ni deposits, Pechenga (1965±87 Ma); impregnated (2433±83 Ma) and redeposited (1903±24 Ma) ores of Ahmavaara intrusion (Finland); Kolvitsa massif metagabbro (1990±92 Ma, which reflect the age of Sm-Nd system closure in sulfide minerals); olivine orthopyroxenites of Sopcha 'Ore bed' (2442±59 Ma); ore gabbronorites of Penikat PGE-bearing layered intrusion (2426±38 Ma (Ekimova et.al., 2011); Pt-Pd gabbro-pegmatite ores (2476± 41 Ma, which agrees well with the U-Pb zircon age - 2470±9 Ma (Bayanova, 2004) and gabbronorites (2483±86 Ma) of PGE Kievey deposit and Fedorova Tundra metagabbroids (2494±54 Ma); Monchetundra gabbronorites - 2489±49 Ma. All investigations are devoted to memory of academician RAS, professor F. Mitrofanov (Russia), he was a leader of scientific school for geology, geochemistry and metallogenesis of ore deposits. The studies were supported by the RFBR 13-05-00493, OFI-M 13-05-12055, Department of Earth Sciences RAS (programs 2 and 4), IGCP-599.

The Potential Effects of Minimum Wage Changes on Naval Accessions

DTIC Science & Technology

2017-03-01

price floor affects the market’s demand for labor and utilizes the two-sector and search models to demonstrate how the minimum wage market ...and search models to demonstrate how the minimum wage market correlates to military ascensions. Finally, the report examines studies that show the...that Derives from a Price Floor. Source: “Price Floor” (n.d.). .....14 Figure 3. Price Floor below the Market . Source: “Price Floor” (n.d

NIR-to-NIR Deep Penetrating Nanoplatforms Y2O3:Nd3+/Yb3+@SiO2@Cu2S toward Highly Efficient Photothermal Ablation.

PubMed

Zhang, Zhiyu; Suo, Hao; Zhao, Xiaoqi; Sun, Dan; Fan, Li; Guo, Chongfeng

2018-05-02

A difunctional nano-photothermal therapy (PTT) platform with near-infrared excitation to near-infrared emission (NIR-to-NIR) was constructed through core-shell structures Y 2 O 3 :Nd 3+ /Yb 3+ @SiO 2 @Cu 2 S (YRSC), in which the core Y 2 O 3 :Nd 3+ /Yb 3+ and shell Cu 2 S play the role of bioimaging and photothermal conversion function, respectively. The structure and composition of the present PTT agents (PTAs) were characterized by powder X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectra. The NIR emissions of samples in the biological window area were measured by photoluminescence spectra under the excitation of 808 nm laser; further, the penetration depth of NIR emission at different wavelengths in biological tissue was also demonstrated by comparing with visible (vis) emission from Y 2 O 3 :Yb 3+ /Er 3+ @SiO 2 @Cu 2 S and NIR emission from YRSC through different injection depths in pork muscle tissues. The photo-thermal conversion effects were achieved through the outer ultrasmall Cu 2 S nanoparticles simultaneously absorb NIR light emission from the core Y 2 O 3 :Nd 3+/ Yb 3+ and the 808 nm excitation source to generate heat. Further, the heating effect of YRSC nanoparticles was confirmed by thermal imaging and ablation of YRSC to Escherichia coli and human hepatoma (HepG-2) cells. Results indicate that the YRSC has potential applications in PTT and NIR imaging in biological tissue.

Improvement of the field-trapping capabilities of bulk Nd Ba Cu O superconductors using Ba Cu O substrates

NASA Astrophysics Data System (ADS)

Matsui, Motohide; Nariki, Shinya; Sakai, Naomichi; Iwafuchi, Kengo; Murakami, Masato

2006-07-01

We used Ba-Cu-O substrates to fabricate bulk Nd-Ba-Cu-O superconductors using a top-seeded melt-growth method. There were several advantages for the use of Ba-Cu-O substrate compared to conventional substrate materials such as MgO, ZrO2, Al2O3, RE123 and RE211 (RE = rare earth). The Ba-Cu-O did not react with the precursor and minimized liquid loss. Accordingly, the introduction of large-sized cracks was suppressed. We also found that Tc values were high at the bottom regions, which was ascribed to the beneficial effect of Ba-Cu-O in suppressing Nd/Ba substitution. As a result, we obtained bulk Nd-Ba-Cu-O superconductors that exhibited fairly good field-trapping capabilities, even at the bottom surfaces.

Pb, Sr, and Nd isotopic compositions of a suite of Late Archean, igneous rocks, eastern Beartooth Mountains: implications for crust-mantle evolution

USGS Publications Warehouse

Wooden, J.L.; Mueller, P.A.

1988-01-01

A series of compositionally diverse, Late Archean rocks (2.74-2.79 Ga old) from the eastern Beartooth Mountains, Montana and Wyoming, U.S.A., have the same initial Pb, Sr, and Nd isotopic ratios. Lead and Sr initial ratios are higher and Nd initial ratios lower than would be expected for rocks derived from model mantle sources and strongly indicate the involvement of an older crustal reservoir in the genesis of these rocks. Crustal contamination during emplacement can be ruled out for a variety of reasons. Instead a model involving subduction of continental detritus and contamination of the overlying mantle as is often proposed for modern subduction environments is preferred. This contaminated mantle would have all the isotopic characteristics of mantle enriched by internal mantle metasomatism but would require no long-term growth or changes in parent to daughter element ratios. This contaminated mantle would make a good source for some of the Cenozoic mafic volcanics of the Columbia River, Snake River Plain, and Yellowstone volcanic fields that are proposed to come from ancient, enriched lithospheric mantle. The isotopic characteristics of the 2.70 Ga old Stillwater Complex are a perfect match for the proposed contaminated mantle which provides an alternative to crustal contamination during emplacement. The Pb isotopic characteristics of the Late Archean rocks of the eastern Beartooth Mountains are similar to those of other Late Archean rocks of the Wyoming Province and suggest that Early Archean, upper crustal rocks were common in this terrane. The isotopic signatures of Late Archean rocks in the Wyoming Province are distinctive from those of other Archean cratons in North America which are dominated by a MORB-like, Archean mantle source (Superior Province) and/or a long-term depleted crustal source (Greenland). ?? 1988.

Phonon transport control by nanoarchitecture including epitaxial Ge nanodots for Si-based thermoelectric materials

PubMed Central

Yamasaka, Shuto; Nakamura, Yoshiaki; Ueda, Tomohiro; Takeuchi, Shotaro; Sakai, Akira

2015-01-01

Phonon transport in Si films was controlled using epitaxially-grown ultrasmall Ge nanodots (NDs) with ultrahigh density for the purpose of developing Si-based thermoelectric materials. The Si/Ge ND stacked structures, which were formed by the ultrathin SiO2 film technique, exhibited lower thermal conductivities than those of the conventional nanostructured SiGe bulk alloys, despite the stacked structures having a smaller Ge fraction. This came from the large thermal resistance caused by phonon scattering at the Si/Ge ND interfaces. The phonon scattering can be controlled by the Ge ND structure, which was independent of Si layer structure for carrier transport. These results demonstrate the effectiveness of ultrasmall epitaxial Ge NDs as phonon scattering sources, opening up a route for the realisation of Si-based thermoelectric materials. PMID:26434678

The Herschel-SPIRE Point Source Catalog Version 2

NASA Astrophysics Data System (ADS)

Schulz, Bernhard; Marton, Gábor; Valtchanov, Ivan; María Pérez García, Ana; Pintér, Sándor; Appleton, Phil; Kiss, Csaba; Lim, Tanya; Lu, Nanyao; Papageorgiou, Andreas; Pearson, Chris; Rector, John; Sánchez Portal, Miguel; Shupe, David; Tóth, Viktor L.; Van Dyk, Schuyler; Varga-Verebélyi, Erika; Xu, Kevin

2018-01-01

The Herschel-SPIRE instrument mapped about 8% of the sky in Submillimeter broad-band filters centered at 250, 350, and 500 microns (1199, 857, 600 GHz) with spatial resolutions of 17.9”, 24.2”, and 35.4” respectively. We present here the 2nd version of the SPIRE Point Source Catalog (SPSC). Stacking on WISE 22 micron catalog sources led to the identification of 108 maps, out of 6878, that had astrometry offsets of greater than 5”. After fixing these deviations and re-derivation of all affected map-mosaics, we repeated the systematic and homogeneous source extraction performed on all maps, using an improved version of the 4 different photometry extraction methods that were already employed in the generation of the first version catalog. Only regions affected by strong Galactic emission, mostly in the Galactic Plane, were excluded, as they exceeded the limits of the available source extraction methods. Aimed primarily at point sources, that allow for the best photometric accuracy, the catalog contains also significant fractions of slightly extended sources. With most SPIRE maps being confusion limited, uncertainties in flux densities were established as a function of structure noise and flux density, based on the results of artificial source insertion experiments into real data along a range of celestial backgrounds. Many sources have been rejected that do not pass the imposed SNR threshold, especially at flux densities approaching the extragalactic confusion limit. A range of additional flags provide information on the reliability of the flux information, as well as the spatial extent and orientation of a source. The catalog should be particularly helpful for determining cold dust content in extragalactic and galactic sources with low to moderate background confusion. We present an overview of catalog construction, detailed content, and validation results, with focus on the improvements achieved in the second version that is soon to be released.

Residential Selection across the Life Course: Adolescent Contextual and Individual Determinants of Neighborhood Disadvantage in Mid-Adulthood

PubMed Central

Gustafsson, Per E.; San Sebastian, Miguel; Janlert, Urban; Theorell, Töres; Westerlund, Hugo; Hammarström, Anne

2013-01-01

Background Numerous cross-sectional studies have examined neighborhood effects on health. Residential selection in adulthood has been stressed as an important cause of selection bias but has received little empirical attention, particularly its determinants from the earlier life course. The present study aims to examine whether neighborhood, family, school, health behaviors and health in adolescence are related to socioeconomic disadvantage of one's neighborhood of residence in adulthood. Methods Based on the prospective Northern Swedish Cohort (analytical N = 971, 90.6% retention rate), information was collected at age 16 years concerning family circumstances, school adjustment, health behaviors and mental and physical health. Neighborhood register data was linked to the cohort and used to operationalize aggregated measures of neighborhood disadvantage (ND) at age 16 and 42. Data was analyzed with linear mixed models, with ND in adulthood regressed on adolescent predictors and neighborhood of residence in adolescence as the level-2 unit. Results Neighborhood disadvantage in adulthood was clustered by neighborhood of residence in adolescence (ICC = 8.6%). The clustering was completely explained by ND in adolescence. Of the adolescent predictors, ND (b = .14 (95% credible interval = .07–.22)), final school marks (b = −.18 (−.26–−.10)), socioeconomic disadvantage (b = .07 (.01–.14)), and, with borderline significance, school peer problems (b = .07 (−.00–.13)), were independently related to adulthood ND in the final adjusted model. In sex-stratified analyses, the most important predictors were school marks (b = −.21 (−.32–−.09)) in women, and neighborhood of residence (ICC = 15.5%) and ND (b = .20 (.09–.31)) in men. Conclusions These findings show that factors from adolescence – which also may impact on adult health – could influence the neighborhood context in which one will live in adulthood. This indicates that residential selection bias in neighborhood effects on health research may have its sources in early life. PMID:24278263

Large magnetic response in (Bi4Nd)Ti3(Fe0.5Co0.5)O15 ceramic at room-temperature

NASA Astrophysics Data System (ADS)

Yang, F. J.; Su, P.; Wei, C.; Chen, X. Q.; Yang, C. P.; Cao, W. Q.

2011-12-01

Ceramics of Nd/Co co-substituted Bi5Ti3FeO15, i.e., (Bi4Nd)Ti3(Fe0.5Co0.5)O15 were prepared by the conventional solid-state reaction method. The X-ray diffraction pattern demonstrates that the sample of the layered perovskite phase was successfully obtained, even if little Bi-deficient pyrochlore Bi2Ti2O7 also existed. The ferroelectric and magnetic Curie temperatures were determined to be 1077 K and 497 K, respectively. The multiferroic property of the sample at room temperature was demonstrated by ferroelectric and magnetic measurements. Remarkably, by Nd/Co co-substituting, the sample exhibited large magnetic response with 2Mr = 330 memu/g and 2Hc = 562 Oe at applied magnetic field of 8 kOe at room temperature. The present work suggests the possibility of doped Bi5Ti3FeO15 as a potential multiferroic.

The feasibility and concurrent validity of performing the Movement Assessment Battery for Children - 2nd Edition via telerehabilitation technology.

PubMed

Nicola, Kristy; Waugh, Jemimah; Charles, Emily; Russell, Trevor

2018-06-01

In rural and remote communities children with motor difficulties have less access to rehabilitation services. Telerehabilitation technology is a potential method to overcome barriers restricting access to healthcare in these areas. Assessment is necessary to guide clinical reasoning; however it is unclear which paediatric assessments can be administered remotely. The Movement Assessment Battery for Children - 2nd Edition is commonly used by various health professionals to assess motor performance of children. The aim of this study was to investigate the feasibility and concurrent validity of performing the Movement Assessment Battery for Children - 2nd Edition remotely via telerehabilitation technology compared to the conventional in-person method. Fifty-nine children enrolled in a state school (5-11 years old) volunteered to perform one in-person and one telerehabilitation mediated assessment. The order of the method of delivery and the therapist performing the assessment were randomized. After both assessments were complete, a participant satisfaction questionnaire was completed by each child. The Bland-Altman limits of agreement for the total test standard score were -3.15 to 3.22 which is smaller than a pre-determined clinically acceptable margin based on the smallest detectable change. This study establishes the feasibility and concurrent validity of the administration of the Movement Assessment Battery for Children - 2nd Edition via telerehabilitation technology. Overall, participants perceived their experience with telerehabilitation positively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Abrupt Late Holocene Shift in Atmospheric Circulation Recorded by Mineral Dust in the Siple Dome Ice Core, Antarctica

NASA Astrophysics Data System (ADS)

Koffman, B. G.; Goldstein, S. L.; Kaplan, M. R.; Winckler, G.; Bory, A. J. M.; Biscaye, P.

2015-12-01

Atmospheric dust directly influences Earth's climate by altering the radiative balance and by depositing micronutrients in the surface ocean, affecting global biogeochemical cycling. In addition, mineral dust particles provide observational evidence constraining past atmospheric circulation patterns. Because dust can originate from both local and distant terrestrial sources, knowledge of dust provenance can substantially inform our understanding of past climate history, atmospheric transport pathways, and differences in aerosol characteristics between glacial and interglacial climate states. Dust provenance information from Antarctic ice cores has until now been limited to sites in East Antarctica. Here we present some of the first provenance data from West Antarctica. We use Sr-Nd isotopes to characterize dust extracted from late Holocene ice (~1000-1800 C.E.) from the Siple Dome ice core. The data form a tight array in Sr-Nd isotope space, with 87Sr/86Sr ranging between ~0.7087 and 0.7102, and ɛNd ranging between ~ -7 and -16. This combination is unique for Antarctica, with low Nd and low Sr isotope ratios compared to high-elevation East Antarctic sites, requiring a dust source from ancient (Archean to early Proterozoic) and unweathered continental crust, which mixes with young volcanic material. Both components are likely sourced from Antarctica. We also observe significant, systematic variability in Sr and Nd isotopic signatures through time, reflecting changes in the mixing ratio of these sources, and hypothesize that these changes are driven by shifts in circulation patterns. A large change occurs over about 10 years at ca. 1125 C.E. (ΔɛNd = +3 and Δ87Sr/86Sr = -0.0014). This shift coincides with changes in climate proxies in Southern Hemisphere paleoclimate records reflecting variability in the Westerlies. We therefore interpret the shift in dust provenance at Siple Dome to be related to larger-scale circulation changes. In general, the observed shifts in the particle source signatures indicate that dust transport pathways to and around the West Antarctic Ice Sheet are highly responsive to perturbations in atmospheric circulation, and can record rapid shifts in provenance.

Fiber optic systems in the UV region

NASA Astrophysics Data System (ADS)

Huebner, Michael; Meyer, H.; Klein, Karl-Friedrich; Hillrichs, G.; Ruetting, Martin; Veidemanis, M.; Spangenberg, Bernd; Clarkin, James P.; Nelson, Gary W.

2000-05-01

Mainly due to the unexpected progress in manufacturing of solarization-reduced all-silica fibers, new fiber-optic applications in the UV-region are feasible. However, the other components like the UV-sources and the detector- systems have to be improved, too. Especially, the miniaturization is very important fitting to the small-sized fiber-optic assemblies leading to compact and mobile UV- analytical systems. Based on independent improvements in the preform and fiber processing, UV-improved fibers with different properties have been developed. The best UV-fiber for the prosed applications is selectable by its short and long-term spectral behavior, especially in the region from 190 to 350 nm. The spectrum of the UV-source and the power density in the fiber have an influence on the nonlinear transmission and the damaging level; however, hydrogen can reduce the UV-defect concentration. After determining the diffusion processes in the fiber, the UV-lifetime in commercially available all-silica fibers can be predicted. Newest results with light from deuterium-lamps, excimer- lasers and 5th harmonics of Nd:YAG laser will be shown. Many activities are in the field of UV-sources. In addition to new UV-lasers like the Nd:YAG laser at 213 nm, a new low- power deuterium-lamp with smaller dimensions has been introduced last year. Properties of this lamp will be discussed, taking into account some of the application requirements. Finally, some new applications with UV-fiber optics will be shown; especially the TLC-method can be improved significantly, combining a 2-row fiber-array with a diode-array spectrometer optimized for fiber-optics.

Windows Memory Forensic Data Visualization

DTIC Science & Technology

2014-06-12

clustering characteristics (Bastian, et al, 2009). The software is written in Java and utilizes the OpenGL library for rendering graphical content...Toolkit 2 nd ed. Burlington MA: Syngress. D3noob. (2013, February 8). Using a MYSQL database as a source of data. Message posted to http

Sr and Nd Data for Upper Eocene Spherule Layers

NASA Technical Reports Server (NTRS)

Liu, Shaobin; Glass, B. P.; Ngo, H. H.; Papanastassiou, D. A.; Wasserburg, G. J.

2001-01-01

Sr and Nd data for clinopyroxene-bearing (cpx) spherules from three sites support conclusions that there is only one cpx spherule layer and that the source crater may be Popigai. Additional information is contained in the original extended abstract.

Antarctic climate, Southern Ocean circulation patterns, and deep water formation during the Eocene

NASA Astrophysics Data System (ADS)

Huck, Claire E.; van de Flierdt, Tina; Bohaty, Steven M.; Hammond, Samantha J.

2017-07-01

We assess early-to-middle Eocene seawater neodymium (Nd) isotope records from seven Southern Ocean deep-sea drill sites to evaluate the role of Southern Ocean circulation in long-term Cenozoic climate change. Our study sites are strategically located on either side of the Tasman Gateway and are positioned at a range of shallow (<500 m) to intermediate/deep ( 1000-2500 m) paleowater depths. Unradiogenic seawater Nd isotopic compositions, reconstructed from fish teeth at intermediate/deep Indian Ocean pelagic sites (Ocean Drilling Program (ODP) Sites 738 and 757 and Deep Sea Drilling Project (DSDP) Site 264), indicate a dominant Southern Ocean-sourced contribution to regional deep waters (ɛNd(t) = -9.3 ± 1.5). IODP Site U1356 off the coast of Adélie Land, a locus of modern-day Antarctic Bottom Water production, is identified as a site of persistent deep water formation from the early Eocene to the Oligocene. East of the Tasman Gateway an additional local source of intermediate/deep water formation is inferred at ODP Site 277 in the SW Pacific Ocean (ɛNd(t) = -8.7 ± 1.5). Antarctic-proximal shelf sites (ODP Site 1171 and Site U1356) reveal a pronounced erosional event between 49 and 48 Ma, manifested by 2 ɛNd unit negative excursions in seawater chemistry toward the composition of bulk sediments at these sites. This erosional event coincides with the termination of peak global warmth following the Early Eocene Climatic Optimum and is associated with documented cooling across the study region and increased export of Antarctic deep waters, highlighting the complexity and importance of Southern Ocean circulation in the greenhouse climate of the Eocene.

Petrology and geochemistry of late-stage intrusions of the A-type, mid-Proterozoic Pikes Peak batholith (Central Colorado, USA): Implications for petrogenetic models

USGS Publications Warehouse

Smith, D.R.; Noblett, J.; Wobus, R.A.; Unruh, D.; Douglass, J.; Beane, R.; Davis, C.; Goldman, S.; Kay, G.; Gustavson, B.; Saltoun, B.; Stewart, J.

1999-01-01

The ~1.08 Ga anorogenic, A-type Pikes Peak batholith (Front Range, central Colorado) is dominated by coarse-grained, biotite ?? amphibole syenogranites and minor monzogranites, collectively referred to as Pikes Peak granite (PPG). The batholith is also host to numerous small, late-stage plutons that have been subdivided into two groups (e.g. Wobus, 1976. Studies in Colorado Field Geology, Colorado School of Mines Professional Contributions, Colorado): (1) a sodic series (SiO2= ~44-78 wt%; K/Na=0.32-1.36) composed of gabbro, diabase, syenite/quartz syenite and fayalite and sodic amphibole granite; and (2) a potassic series (SiO2= ~ 70-77 wt%; K/Na=0.95-2.05), composed of biotite granite and minor quartz monzonite. Differences in major and trace element and Nd isotopic characteristics for the two series indicate different petrogenetic histories. Potassic granites of the late-stage intrusions appear to represent crustal anatectic melts derived from tonalite sources, based on comparison of their major element compositions with experimental melt products. In addition, Nd isotopic characteristics of the potassic granites [??(Nd)(1.08 Ga) = -0.2 to -2.7] overlap with those for tonalites/granodiorites [ca 1.7 Ga Boulder Creek intrusions; ??(Nd)(1.08 Ga) = -2.4 to -3.6] exposed in the region. Some of the partial melts evolved by fractionation dominated by feldspar. The late-stage potassic granites share geochemical characteristics with most of the PPG, which is also interpreted to have an anatectic origin involving tonalitic crust. The origin of monzogranites associated with the PPG remains unclear, but mixing between granitic and mafic or intermediate magmas is a possibility. Syenites and granites of the sodic series cannot be explained as crustal melts, but are interpreted as fractionation products of mantle-derived mafic magmas with minor crustal input. High temperature and low oxygen fugacity estimates (e.g. Frost et al., 1988. American Mineralogist 73, 727-740) support a basalt fractionation origin, as do ??(Nd) values for sodic granitoids [??(Nd)(1.08 Ga) = +2.2 to -0.7], which are higher than ??(Nd) values for Colorado crust at 1.08 Ga (ca -1.0 to -4.0). Enrichments in incompatible elements (e.g. rare earth elements, Rb, Y) and depletions in compatible elements (e.g. Cr, Sr, Ba) in the sodic granitoids compared to coeval mafic rocks are also consistent with fractionation. Accessory mineral fractionation, release of fluorine-rich volatiles and/or removal of pegmatitic fluids could have modified abundances of Ce, Nb, Zr and Y in some sodic granitoid magmas. Gabbros and mafic dikes associated with the sodic granitoids have ??(Nd)(1.08 Ga) of -3.0 to +3.5, which are lower than depleted mantle at 1.08 Ga, and their trace element characteristics suggest derivation from mantle sources that were previously affected by subduction-related processes. However, it is difficult to characterize the mantle component in these magmas, because assimilation of crust during magma ascent could also result in their observed geochemical features. The Pikes Peak batholith is composed of at least two petrogenetically different granite types, both of which exhibit geochemical characteristics typical of A-type granites. Models proposed for the petrogenesis of the granitoids imply the existence of mafic rocks at depth and addition of juvenile material to the crust in central Colorado at ~ 1.1 Ga.

Generation and Evolution of Quaternary Magmas Beneath Tengchong: Sr-Nd-Pb-Hf Isotope and Zircon U-series Age Constraints

NASA Astrophysics Data System (ADS)

Zou, H.; Ma, M.; Fan, Q.; Xu, B.; Li, S. Q.; Zhao, Y.; King, D. T., Jr.

2017-12-01

The Tengchong volcanic field on the southeastern margin of the Tibetan Plateau represents rare Quaternary volcanic eruptions on the plateau. The Quaternary Tengchong volcanic field formed high-potassium calc-alkaline volcanic rocks that include trachybasalts, basaltic trachyandesites, trachyandesites, and dacites. Herein, we present comprehensive Nd-Sr-Pb-Hf isotopic and elemental data for trachybasalts, basaltic trachyandesites, and trachyandesites from four young Tengchong volcanoes at Maanshan, Dayingshan, Heikongshan, and Laoguipo, in order to understand their magma genesis and evolution. Nd-Sr-Pb-Hf isotopes for the primitive Tengchong magma (trachybasalts with SiO2 <52.5 wt. % and MgO >5.5% wt. %) reflect a heterogeneous enriched mantle source. High Th/U, Th/Ta, and Rb/Nb ratios and Nd-Sr-Pb-Hf isotope characteristics of the primitive magmas suggest that the enriched mantle beneath Tengchong formed as a result of subduction of clay-rich sediments, which probably came from the Indian continental plate. Partial melting of the enriched mantle was generated by deep continental subduction coupled with recent regional extension in the Tengchong area. With regard to the evolved magmas (basaltic trachyandesites and trachyandesites), good correlations between SiO2 content and the ratios 87Sr/86Sr, 143Nd/144Nd, 206Pb/204Pb, and 177Hf/176Hf strongly suggest that the combined assimilation and fractional crystallization (AFC) was an important process during magma evolution to form these basaltic trachyandesites and trachyandesites. Uranium-series zircon dating on these evolved lavas from Tengchong is used to constrain their magma evolution and residence timescales.

Natural Aerosols Explain Seasonal and Spatial Patterns of Southern Ocean Cloud Albedo

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

McCoy, Daniel; Burrows, Susannah M.; Wood, R.

2015-07-17

Small particles called aerosols act as nucleation sites for cloud drop formation, affecting clouds and cloud properties – ultimately influencing the cloud dynamics, lifetime, water path and areal extent that determine the reflectivity (albedo) of clouds. The concentration Nd of droplets in clouds that influences planetary albedo is sensitive to the availability of aerosol particles on which the droplets form. Natural aerosol concentrations not only affect cloud properties themselves, but also modulate the sensitivity of clouds to changes in anthropogenic aerosols. Here, it is shown that modeled natural aerosols, principally marine biogenic primary and secondary aerosol sources, explain more thanmore » half of the spatiotemporal variability in satellite-observed Nd. Enhanced Nd over regions of high biological activity is found to be driven primarily by high concentrations of sulfate aerosol at lower Southern Ocean latitudes (35-45°S) and by organic matter in sea spray aerosol at higher latitudes (45-55°S). Biogenic sources are estimated to increase the summertime mean reflected solar radiation in excess of 10 W m-2 over parts of the Southern Ocean, which is comparable to the annual mean increases expected from anthropogenic aerosols over heavily polluted regions of the Northern Hemisphere.« less

Structure Evolution and Multiferroic Properties in Cobalt Doped Bi4NdTi3Fe1-xCoxO15-Bi3NdTi2Fe1-xCoxO12-δ Intergrowth Aurivillius Compounds

PubMed Central

Zhang, D. L.; Huang, W. C.; Chen, Z. W.; Zhao, W. B.; Feng, L.; Li, M.; Yin, Y. W.; Dong, S. N.; Li, X. G.

2017-01-01

Here, we report the structure evolution, magnetic and ferroelectric properties in Co-doped 4- and 3-layered intergrowth Aurivillius compounds Bi4NdTi3Fe1-xCoxO15-Bi3NdTi2Fe1-xCoxO12-δ. The compounds suffer a structure evolution from the parent 4-layered phase (Bi4NdTi3FeO15) to 3-layered phase (Bi3NdTi2CoO12-δ) with increasing cobalt doping level from 0 to 1. Meanwhile the remanent magnetization and polarization show opposite variation tendencies against the doping level, and the sample with x = 0.3 has the largest remanent magnetization and the smallest polarization. It is believed that the Co concentration dependent magnetic properties are related to the population of the Fe3+ -O-Co3+ bonds, while the suppressed ferroelectric polarization is due to the enhanced leakage current caused by the increasing Co concentration. Furthermore, the samples (x = 0.1–0.7) with ferromagnetism show magnetoelectric coupling effects at room temperature. The results indicate that it is an effective method to create new multiferroic materials through modifying natural superlattices. PMID:28272495

Double NIR laser stimulation and enhancing the thermal sensitivity of Er3+/Tm3+/Nd3+ doped multilayer core-shell nanoparticles.

PubMed

Ba, Zhaojing; Hu, Min; Zhao, Yiming; Wang, Yiqing; Wang, Jing; Zhang, Zhenxi

2018-08-31

Non-contact thermal sensors are important devices to study cellular processes and monitor temperature in vivo. Herein, a novel highly sensitive nanothermometer based on NaYF 4 :Yb,Er@ NaYF 4 @NaYF 4 :Yb,Tm@ NaYF 4 :Nd (denoted as Er@Y@Tm@Nd) was prepared by a facile solvothermal method. When excited by the near-infrared (NIR) light of 808 and 980 nm, the as-prepared Er@Y@Tm@Nd nanoparticles could emit both blue and green light, respectively, since the lanthanide cations responsible for these emissions are gathered inside this nanostructure. The green and blue light intensity ratio exhibits obvious temperature dependence in the range of the physiological temperature. Additionally, the fluorescence intensity of Er 3+ and Tm 3+ are also greatly enhanced due to the multilayer structure that implies avoiding the Er 3+ and Tm 3+ energy cross-relaxation by introduction of a NaYF 4 wall between them. The as-prepared core-shell-shell-shell structure with Er 3+ and Tm 3+ in different layers improves dozens of times of the thermal sensitivity based on the non-thermal coupling levels of the probe: the maximum values for the sensitivity are 2.95% K -1 (I Er-521 /I Tm-450 ) and 6.30% K -1 (I Tm-474 /I Er-541 ) when excited by 980 and 808 nm laser sources, respectively. These values are well above those previously reported (<0.7% K -1 ), indicating that the prepared nanostructures are temperature sensors with excellent thermal sensitivity and sensitive to NIR wavelength excitation that makes them highly preferred for thermal detection.

Petrogenesis of Late Triassic ultramafic rocks from the Andong Ultramafic Complex, South Korea

NASA Astrophysics Data System (ADS)

Kim, Nak Kyu; Choi, Sung Hi

2016-11-01

To constrain the source and tectonomagmatic processes that gave rise to the Andong Ultramafic Complex (AUC) in South Korea, we determined the clinopyroxene Sr-Nd-Hf-Pb isotope and trace element compositions as well as the whole-rock and mineral compositions for the Late Triassic (ca. 222 Ma) ultramafic rocks from the complex. They are composed of dunites, wehrlites, pyroxene/hornblende peridotites, and pyroxenites. The constituent minerals are olivines, diopsides/augites, bronzites, calcic-amphiboles, and spinels. Clinopyroxenes exhibit a convex-upward rare earth element (REE) pattern, with an apex at Sm. The whole-rock compositions plot away from the residual mantle peridotite trends, with variable but lower Al2O3 and SiO2 contents, and higher CaO, FeO*, and TiO2 contents at a given value of MgO. Estimated equilibrium temperatures for the AUC rocks range from 420 to 780 °C. These observations, together with the absence of reaction or melt impregnation textures, indicate that the AUC ultramafic rocks are magmatic cumulates emplaced within the crust rather than residual mantle or mantle-melt reaction products. The AUC clinopyroxenes have compositions intermediate between the oceanic island basalt- and arc basalt-related cumulate clinopyroxenes. The AUC spinels have lower Cr#s than the arc-related magmatic cumulate spinels. They plot within the field for spinels from mid-ocean ridge basalts (MORB) on a TiO2 vs. Cr# diagram. However, the AUC clinopyroxenes have much more radiogenic Sr ([87Sr/86Sr]i = 0.70554 to 0.70596), unradiogenic Nd ([εNd]i = - 1.0 to - 0.3), and Hf ([εHf]i = + 4.4 to + 6.6) isotopic compositions than those of the MORB or fore-arc basalts (FAB). In the Sr-Nd isotopic correlation diagram, the AUC clinopyroxenes plot in the enriched extension of the "mantle array". They also have more elevated 207Pb/204Pb ratios at a given 206Pb/204Pb than those of the MORB or FAB. In the Nd-Hf isotope space, the AUC clinopyroxenes have somewhat elevated 176Hf/177Hf ratios at a given 143Nd/144Nd compared to the "mantle-crust" array. These observations indicate that the sub-continental lithospheric mantle (SCLM) overprinted by secondary volatile-rich silicate melts might be the principal source of the AUC magmatism. Heat from the upwelling asthenosphere, through the slab window produced by detachment of the oceanic slab from the buoyant continental lithosphere during continental collision between the North and South China Cratons, might lead to partial melting of the overlying metasomatized SCLM, resulting in the post-collisional Triassic magmatism in South Korea.

Tracing Tethyan Phosphogenesis From Temporal Variations of 44Ca/42Ca and 143Nd/144Nd Isotope Ratios in Francolites and P Accumulation

NASA Astrophysics Data System (ADS)

Soudry, D.; Glenn, C.; Nathan, Y.; Segal, I.; Vonderhaar, D.

2004-12-01

Measurements of 44Ca/42Ca and 143Nd/144 isotope ratios in carbonate fluorapatite (CFA) through the Cretaceous-Eocene of the Negev (Israel) and of other sites in the Tethys margins, together with quantified rates of P and Ca accumulation and bulk sedimentation, allow us to understand variations of Tethyan phosphogenesis in time and space. The data provide a ˜ 90 m.y. (Hauterivian-Eocene) record of the Ca and Nd isotopic composition in 72 CFA samples representing 25 time-stratigraphic phosphate levels. Similar temporal changes are displayed by δ 44Ca and ɛ NdT. δ 44Ca is much lighter in the Hauterivian-Albian (δ 44Ca = - 0. 19 to - 0.06 ‰ ; n = 9) than in the Campanian-Eocene (δ 44Ca = + 0.29 to + 0.40 ‰ ; n = 41), whereas ɛ NdT increases from continental crust-like values in the Hauterivian-Albian (ɛ NdT = -12.8 to - 10.9; n = 8) to more radiogenic Pacific-like values (ɛ NdT = - 7.5 to - 6.2; n = 27) in the Campanian. Both δ 44Ca and ɛ NdT peaks in the Campanian coincide with the peak of Tethyan phosphogenesis in the Negev, marked by a sharp rise in P accumulation rates (from < 200 μ mole.cm-2 kyr-1 in pre-Campanian times to ˜ 1700 < 200 μ mole.cm-2 kyr-1 in the Campanian) and by a decrease in the rates of Ca accumulation and bulk sedimentation. The coincident increases of δ 44Ca, ɛ NdT, and P accumulation in the Negev during the Campanian is interpreted as the combined effect of the Late Cretaceous global sea level rise, the development of a long-transit, westward-flowing circumglobal Tethyan current enhanced by widening of the Caribbean threshold at those times, and a favorable paleolatitude (8° -15° ) of the south Tethys shelf in the path of easterly winds. Extensive flooding of continental platforms, induced by the Late Cretaceous global sea level rise, probably reduced the influx of riverine Ca to oceans and increased carbonate deposition on shelves both causing seawater enrichment with heavy Ca. Similarly, intensification of ocean circulation, causing more incursion of Pacific water masses into the Tethys, probably also led to increase both the input of radiogenic Nd into the Tethys and the availability of dissolved P in photic waters. The much lower ɛ NdT values recorded in N. Africa CFA during Eocene times (ɛ NdT = - 10.0 to - 9.4) suggests Atlantic waters as main source of dissolved P for fuelling phosphate deposition in this area.

The composition and distribution of the rejuvenated component across the Hawaiian plume: Hf-Nd-Sr-Pb isotope systematics of Kaula lavas and pyroxenite xenoliths

NASA Astrophysics Data System (ADS)

Bizimis, Michael; Salters, Vincent J. M.; Garcia, Michael O.; Norman, Marc D.

2013-10-01

Rejuvenated volcanism refers to the reemergence of volcanism after a hiatus of 0.5-2 Ma following the voluminous shield building stage of Hawaiian volcanoes. The composition of the rejuvenated source and its distribution relative to the center of the plume provide important constraints on the origin of rejuvenated volcanism. Near-contemporaneous lavas from the Kaula-Niihau-Kauai ridge and the North Arch volcanic field that are aligned approximately orthogonally to the plume track can constrain the lateral geochemical heterogeneity and distribution of the rejuvenated source across the volcanic chain. Nephelinites, phonolites and pyroxenite xenoliths from Kaula Island have radiogenic Hf, Nd and unradiogenic Sr isotope compositions consistent with a time-integrated depleted mantle source. The pyroxenites and nephelinites extend to the lowest 208Pb/204Pb reported in Hawaiian rocks. These data, along with new Pb isotope data from pyroxenites from the Salt Lake Crater (Oahu) redefine the composition of the depleted end-member of the Hawaiian rejuvenated source at 208Pb/204Pb=37.35±0.05, 206Pb/204Pb = 17.75±0.03, ɛNd = 9-10, ɛHf ˜16-17 and 87Sr/88Sr <0.70305. The revised isotope composition also suggests that this depleted component may contribute to LOA and KEA trend shield stage Hawaiian lavas, consistent with the rejuvenated source being part of the Hawaiian plume and not entrained upper mantle. The isotope systematics of rejuvenated magmas along the Kaula-Niihau-Kauai-North Arch transect are consistent with a larger proportion of the rejuvenated depleted component in the periphery of the plume track rather than along its axis.

Sm-Nd-Pu timepieces in the Angra dos Reis meteorite

NASA Technical Reports Server (NTRS)

Lugmair, G. W.; Marti, K.

1977-01-01

Isotope ratios and age estimations are presented for the ultramafic pyroxenite Angra dos Reis meteorite. A pyroxene-phosphate internal isochron age of 4.55 plus or minus 0.04 eons was obtained, in agreement with reported Pb-Pb ages. It is suggested that Sm-146 decay led to an increase in the ratio of Nd-142 to Nd-144 in pyroxene, which is greater than the ratio of the Nd isotopes in phosphates. The effect of Pu-244 on the fission xenon components in pyroxene and phosphate is examined. The ratios of Pu-244 to Nd, U-238, and Th-232 are compared for pyroxene and phosphate separates. The exposure age of the meteorite, as obtained by the Kr-81 to Kr-83 method, was found to be 55.5 plus or minus 1.2 million years.

Higher social intelligence can impair source memory.

PubMed

Barber, Sarah J; Franklin, Nancy; Naka, Makiko; Yoshimura, Hiroki

2010-03-01

Source monitoring is made difficult when the similarity between candidate sources increases. The current work examines how individual differences in social intelligence and perspective-taking abilities serve to increase source similarity and thus negatively impact source memory. Strangers first engaged in a cooperative storytelling task. On each trial, a single word was shown to both participants, but only 1 participant was designated to add a story sentence, using this assigned word. As predicted, social intelligence negatively predicted performance in a subsequent source-monitoring task. In a 2nd study, preventing participants from being able to anticipate their partner's next contribution to the story eliminated the effect.

Linking measures of adolescent nicotine dependence to a common latent continuum.

PubMed

Strong, David R; Kahler, Christopher W; Colby, Suzanne M; Griesler, Pamela C; Kandel, Denise

2009-01-01

Using the theoretical model of nicotine dependence (ND) operationalized within the Diagnostic and Statistical Manual of Mental Disorder, fourth Edition (DSM-IV: American Psychiatric [American Psychiatric Association, 1994. Diagnostic and Statistical Manual of Mental Disorders. 4th ed. American Psychiatric Association, Washington, DC]) as a frame of reference, we used methods based in item response theory to link alternative instruments assessing adolescent nicotine dependence severity to a common latent continuum. A multi-ethnic cohort of 6th-10th graders selected from the Chicago Public Schools (CPS) completed five household interviews over 2 years. Youth who reported at least some cigarette use in the last 30 days prior to the interviews at waves W3-W5 completed measures of DSM-IV ND, the Modified Fagertrom Tolerance Questionnaire (mFTQ: Prokhorov et al., 1998) and the Nicotine Dependence Syndrome Scale (NDSS: Shiffman et al., 2004), yielding samples of 253, 241, and 296 respondents at W3-W5, respectively. Confirmatory factor analysis supported a primary dimension of ND. Each instrument's items had complementary and stable relationships to ND across multiple waves of assessment. By aligning symptoms along a common latent ND continuum, we evaluated the consistency of symptoms from different instruments that target similar content. Further, these methods allowed for the examination of the DSM-IV as a continuous index of ND, evaluation of the degree of heterogeneity in levels of ND within groups above and below diagnostic thresholds, and the utility of using the pattern or particular DSM-IV symptoms that led to each score in further differentiating levels of ND. Finally, we examined concurrent validity of the ND continuum and levels of current of smoking at each wave of assessment.

Comparative electronic structure of a lanthanide and actinide diatomic oxide: Nd versus U

NASA Astrophysics Data System (ADS)

Krauss, M.; Stevens, W. J.

2003-01-01

Using a modified version of the Alchemy electronic structure code and relativistic pseudopotentials, the electronic structure of the ground and low lying excited states of UO, NdO, and NdO + have been calculated at the Hartree-Fock (HF) and multiconfiguration self-consistent field (MCSCF) levels of theory. Including results from an earlier study of UO + this provides the information for a comparative analysis of a lanthanide and an actinide diatomic oxide. UO and NdO are both described formally as M +2 O -2 and the cations as M +3 O -2 , but the HF and MCSCF calculations show that these systems are considerably less ionic due to large charge back-transfer in the πorbitals. The electronic states putatively arise from the ligand field (oxygen anion) perturbed f 4 , sf 3 , df 3 , sdf 2 , or s 2 f 2 states of M +2 and f 3 , sf 2 or df 2 states of M +3 . Molecular orbital results show a substantial stabilization of the sf 3 or s 2 f 2 configurations relative to the f 4 or df 3 configurations that are the even or odd parity ground states in the M +2 free ion. The compact f and d orbitals are more destabilized by the anion field than the diffuse s orbital. The ground states of the neutral species are dominated by orbitals arising from the M +2 sf 3 term, and all the potential energy curves arising from this configuration are similar, which allows an estimate of the vibrational frequencies for UO and NdO of 862 cm -1 and 836 cm -1 , respectively. For NdO + and UO + the excitation energies for the Ωstates were calculated with a valence configuration interaction method using ab initio effective spin-orbit operators to couple the molecular orbital configurations. The results for NdO + are very comparable with the results for UO + , and show the vibrational and electronic states to be interleaved.

Laser discrimination by stimulated emission of a phosphor

NASA Technical Reports Server (NTRS)

Mathur, V. K.; Chakrabarti, K.

1991-01-01

A method for discriminating sources of UV, near infrared, and far infrared laser radiation was discovered. This technology is based on the use of a single magnesium sulfide phosphor doubly doped with rare earth ions, which is thermally/optically stimulated to generate colors correlatable to the incident laser radiation. The phosphor, after initial charging by visible light, exhibits green stimulated luminescence when exposed to a near infrared source (Nd: YAG laser). On exposure to far infrared sources (CO2 laser) the phosphor emission changes to orange color. A UV laser produces both an orange red as well as green color. A device using this phosphor is useful for detecting the laser and for discriminating between the near infrared, far infrared, and UV lasers. The technology is also capable of infrared laser diode beam profiling since the radiation source leaves an imprint on the phosphor that can be photographed. Continued development of the technology offers potential for discrimination between even smaller bandwidths within the infrared spectrum, a possible aid to communication or wavemixing devices that need to rapidly identify and process optical signals.

Surface Structure as a Foundation of Nanotechnology

NASA Astrophysics Data System (ADS)

Robinson, Ian

2007-03-01

The three generations of synchrotron sources achieved to date, parasitic, dedicated and undulator-based, have each time revolutionized the field of X-ray diffraction. Surface structure determination, demonstrated (but very difficult) already with Coolidge tube sources, benefited from the enormous flux gain in the first generation, such as SSRL. Dedicated 2nd-generation sources, such as NSLS, allowed in-situ surface preparation and reliable steady beams to be available when a surface was ready to measure. Third generation sources, such as APS, enormously improved the brightness, hence coherence, and thus allowed access to the surfaces of nanoparticles. This talk will illustrate how these technological advances led to two significant scientific breakthroughs. The concept of crystal truncation rods (CTR) led to new views of how the surface is a modification of, but still an extension of the bulk crystal structure. The development of lensless coherent x-ray diffraction (CXD) imaging has allowed access to the structure of nanocrystalline materials by three-dimensional phase mapping of the particle interiors. The structural principles of these new nano materials are being investigated at present using these new methods.

Simultaneous in situ determination of both U-Th-Pb and Sm-Nd isotopes in monazite by laser ablation using a magnetic sector ICP-MS and a multicollector ICP-MS

NASA Astrophysics Data System (ADS)

Goudie, D. J.; Fisher, C. M.; Hanchar, J. M.; Davis, W. J.; Crowley, J. L.; Ayers, J. C.

2012-12-01

We present a method for the simultaneous in situ determination of U-Th-Pb and Sm-Nd isotopes in monazite, using a laser ablation (LA) system coupled to both a magnetic sector inductively coupled plasma mass spectrometer (HR) ICP-MS and a multicollector (MC) ICP-MS. The ablated material is split using a glass Y-connector and transported simultaneously to both mass spectrometers via helium carrier gas. The MC-ICP-MS is configured to provide relative Ce, Gd, and Eu contents, in addition to Sm and Nd. This approach obtains both age (U-Pb), tracer isotope (Sm-Nd), and REE element data (Ce, Gd, and Eu), in the same ablation volume, thus reducing sampling problems associated with fine-scale zoning and other internal structures. The accuracy and precision of the U-Pb data are demonstrated using six well characterized monazite reference materials from the Geological Survey of Canada (three of which are currently used as SHRIMP standards) and agree well with previously determined ID-TIMS ages. The accuracy of the Sm-Nd isotopic data was assessed by comparison to TIMS measurements on a well-characterized in-house monazite standard. The dual LA-ICP-MS method was applied to the Birch Creek Pluton (BCP) in the White Mountains, California in a case study to test the utility of U-Th-Pb dating coupled with Sm-Nd (and Ce, Gd, Eu) isotopic data for solving geologic problems. Previous work on the Cretaceous BCP [1] used Th-Pb ages coupled with O isotopic data to constrain hydrothermal fluid events, as recorded in monazite. The original study suggested that the high delta 18O monazite in Paleozoic country rocks adjacent to the BCP grew in response to fluid alternation associated with the intrusion of the BCP, based on overlapping age with the BCP. New monazite split-stream U-Pb and Sm-Nd data show that monazite from the BCP pluton and monazite from altered country rock have homogenous and overlapping initial Nd isotopic composition, further strengthening the proposal that monazite in altered country rock can be a tracer of fluid alternation events. The split-stream U-Pb ages agrees with new high precision ID-TIMS U-Pb ages from the same monazite grains. These results demonstrate how monazite age and Sm-Nd isotopic data, coupled with delta 18O, can identify hydrothermal monazite and constrain the timing and potential sources of fluid events. [1] Ayers et al., Geology 34 (2006) 653-656.

Magnetocaloric effect in layered NdMn2Ge0.4Si1.6

NASA Astrophysics Data System (ADS)

Wang, J. L.; Campbell, S. J.; Cadogan, J. M.; Studer, A. J.; Zeng, R.; Dou, S. X.

2011-06-01

A giant magnetocaloric effect has been observed in NdMn2Ge0.4Si1.6 associated with the first-order magnetic phase transition from antiferromagnetism to ferromagnetism around TC=36K. The magnetic entropy change -ΔSM and adiabatic temperature change ΔTad have been determined from magnetization and specific heat measurements (B =0-5 T) with -ΔSM calculated by the Maxwell relation and Clausius-Clapeyron method. The values -ΔSMmax=12.3 J kg-1 K-1 and refrigerant capacity ˜95 J/kg for ΔB =0-2 T as derived from the Maxwell relation, together with the small hysteresis (thermal <0.5 K; magnetic field <0.1 T), indicate the potential of NdMn2Ge0.4Si1.6 for refrigeration applications.

OIB signatures in basin-related lithosphere-derived alkaline basalts from the Batain basin (Oman) - Constraints from 40Ar/39Ar ages and Nd-Sr-Pb-Hf isotopes

NASA Astrophysics Data System (ADS)

Witte, M.; Jung, S.; Pfänder, J. A.; Romer, R. L.; Mayer, B.; Garbe-Schönberg, D.

2017-08-01

Tertiary rift-related intraplate basanites from the Batain basin of northeastern Oman have low SiO2 (< 45.6 wt.%), high MgO (> 9.73 wt.%) and moderate to high Cr and Ni contents (Cr > 261 ppm, Ni > 181 ppm), representing near primary magmas that have undergone fractionation of mainly olivine and magnetite. Rare earth element systematics and p-T estimates suggest that the alkaline rocks are generated by different degrees of partial melting (4-13%) of a spinel-peridotite lithospheric mantle containing residual amphibole. The alkaline rocks show restricted variations of 87Sr/86Sr and 143Nd/144Nd ranging from 0.70340 to 0.70405 and 0.51275 to 0.51284, respectively. Variations in Pb isotopes (206Pb/204Pb: 18.59-18.82, 207Pb/204Pb: 15.54-15.56, 208Pb/204Pb: 38.65-38.98) of the alkaline rocks fall in the range of most OIB. Trace element constraints together with Sr-Nd-Pb isotope composition indicate that assimilation through crustal material did not affect the lavas. Instead, trace element variations can be explained by melting of a lithospheric mantle source that was metasomatized by an OIB-type magma that was accumulated at the base of the lithosphere sometimes in the past. Although only an area of less than 1000 km2 was sampled, magmatic activity lasted for about 5.5 Ma with a virtually continuous activity from 40.7 ± 0.7 to 35.3 ± 0.6 Ma. During this period magma composition was nearly constant, i.e. the degree of melting and the nature of the tapped source did not change significantly over time.

Nd-Sr isotopic and geochemical systematics in Cambrian boninites and tholeiites from Victoria, Australia

NASA Astrophysics Data System (ADS)

Nelson, D. R.; Crawford, A. J.; McCulloch, M. T.

1984-11-01

Rocks with boninitic affinities have been recognised in a number of “ophiolites”, including the Cambrian Heathcote and Mt Wellington Greenstone Belts of Victoria. Boninites and high-Mg andesites from the Heathcote Greenstone Belt show a restricted range of initial ɛ Nd values of between +3.3 to +5.8. Extremely refractory boninites from the Mt Wellington Greenstone Belt have ɛ Nd ranging from +1.3 to -9. Ti/Zr is positively correlated with Sm/Nd with the Heathcote lavas generally possessing greater depletion of Ti and enrichment of Zr relative to the middle and heavy REE with increasing LREE/HREE. These data are consistent with the generation of boninites by partial melting of refractory peridotite following invasion by LREE- and Zr-enriched, low ɛ Nd fluids. Tholeiites overlying the boninites in both greenstone belts have flat REE patterns and ɛ Nd˜+5, lower than that anticipated for lavas derived from depleted MORB source reservoirs in the Cambrian, suggesting that their source was also contaminated by a LREE-enriched, low ɛ Nd component similar to that involved in the generation of the Howqua boninites. The added components have characteristics compatible with their derivation from subducted altered oceanic crust and/or from wet subducted sediments. The identification of boninites and other low-Ti lavas in the Victorian greenstone belts is strong evidence for island arc development in southeastern Australia during the Lower Cambrian and provides further support for a subduction-related origin for many ophiolites.

Evolution of continental crust and mantle heterogeneity: Evidence from Hf isotopes

USGS Publications Warehouse

Jonathan, Patchett P.; Kouvo, O.; Hedge, C.E.; Tatsumoto, M.

1982-01-01

We present initial 176Hf/177 Hf ratios for many samples of continental crust 3.7-0.3 Gy old. Results are based chiefly on zircons (1% Hf) and whole rocks: zircons are shown to be reliable carriers of essentially the initial Hf itself when properly chosen on the basis of U-Pb studies. Pre-3.0 Gy gneisses were apparently derived from an unfractionated mantle, but both depleted and undepleted mantle are evident as magma sources from 2.9 Gy to present. This mantle was sampled mainly from major crustal growth episodes 2.8, 1.8 and 0.7 Gy ago, all of which show gross heterogeneity of 176Hf/177Hf in magma sources from ??Hf=0 to +14, or about 60% of the variability of the present mantle. The approximate ??Hf=2??Nd relationship in ancient and modern igneous rocks shows that 176Lu/177Hf fractionates in general twice as much as 147Sm/144Nd in mantle melting processes. This allows an estimation of the relative value of the unknown bulk solid/liquid distribution coefficient for Hf. DLu/DHf=??? 2.3 holds for most mantle source regions. For garnet to be an important residual mantle phase, it must hold Hf strongly in order to preserve Hf-Nd isotopic relationships. The ancient Hf initials are consistent with only a small proportion of recycled older cratons in new continental crust, and with quasi-continuous, episodic growth of the continental crust with time. However, recycling of crust less than 150 My old cannot realistically be detected using Hf initials. The mantle shows clearly the general positive ??Hf resulting from a residual geochemical state at least back to 2.9 Gy ago, and seems to have repeatedly possessed a similar degree of heterogeneity, rather than a continuously-developing depletion. This is consistent with a complex dynamic disequilibrium model for the creation, maintenance and destruction of heterogeneity in the mantle. ?? 1981 Springer-Verlag.

Study on magnetic properties of (Nd0.8Ce0.2)2-xFe12Co2B (x = 0-0.6) alloys

NASA Astrophysics Data System (ADS)

Tan, G. S.; Xu, H.; Yu, L. Y.; Tan, X. H.; Zhang, Q.; Gu, Y.; Hou, X. L.

2017-09-01

In the present work, (Nd0.8Ce0.2)2-xFe12Co2B (x = 0-0.6) permanent alloys are prepared by melt-spinning method. The hard magnetic properties of (Nd0.8Ce0.2)2-xFe12Co2B (x = 0-0.6) alloys annealed at optimum temperatures have been investigated systematically. Depending on the Nd, Ce concentration, the maximum energy product ((BH)max) and remanence (Br) increase gradually with x in the range of 0 ≤ x ≤ 0.4, whereas decrease gradually in the alloys with 0.4 < x ≤ 0.6. It is found that the optimum magnetic properties are obtained at x = 0.4: Hci = 4.9 kOe, Br = 10.1 kG, (BH)max = 13.7 MGOe. Specifically, magnetic field heat treatment below the Curie temperature is applied for (Nd0.8Ce0.2)1.6Fe12Co2B (x = 0.4) annealed ribbons. The magnetic properties Br, (BH)max and squareness are all enhanced after the magnetic field heat treatment. The (BH)max shows a substantial increase from 13.7 MGOe to 16.0 MGOe after the heat treatment at 623 K with a magnetic field of 1 T, which gets 17% improvement compared with that of the sample without a magnetic field heat treatment. We demonstrate that the magnetic field heat treatment plays a certain role in the magnetization reversal behavior and can improve the microstructure of (Nd0.8Ce0.2)1.6Fe12Co2B alloy.

Loss of Life, Evacuation and Emergency Management - Application of Dutch Models to US Case Studies

DTIC Science & Technology

2012-12-18

Risks to people M es o: Z on e or lo ca tio n Instability tests Jonkman 1953 D eK ay a nd M cC le lla nd G ra ha m Katrina HEC -FIA...mortality functions (Jonkman) o 2.2.2 New Orleans / Katrina mortality functions (Jonkman) o 2.2.3 HEC FIA approach (USACE) o 2.2.4. Loss of life methods...comparison (USACE) • 2.3 Dutch Evacuation and Evacuaid approach (Kolen) o 2.3.1 Evacuation approach implemented in HEC FIA (USACE) o 2.3.2 Evacuation

Sr and Nd isotopic and trace element compositions of Quaternary volcanic centers of the Southern Andes

USGS Publications Warehouse

Futa, K.; Stern, C.R.

1988-01-01

Isotopic compositions of samples from six Quaternary volcanoes located in the northern and southern extremities of the Southern Volcanic Zone (SVZ, 33-46??S) of the Andes and from four centers in the Austral Volcanic Zone (AVZ, 49-54??S) range for 87Sr 86Sr from 0.70280 to 0.70591 and for 143Nd 144Nd from 0.51314 to 0.51255. The ranges are significantly greater than previously reported from the southern Andes but are different from the isotopic compositions of volcanoes in the central and northern Andes. Basalts and basaltic andesites from three centers just north of the Chile Rise-Trench triple junction have 87Sr 86Sr, 143Nd 144Nd, La Yb, Ba La, and Hf Lu that lie within the relatively restricted ranges of the basic magmas erupted from the volcanic centers as far north as 35??S in the SVZ of the Andes. The trace element and Sr and Nd isotopic characteristics of these magmas may be explained by source region contamination of subarc asthenosphere, with contaminants derived from subducted pelagic sediments and seawater-altered basalts by dehydration of subducted oceanic lithosphere. In the northern extremity of the SVZ between 33?? and 34??S, basaltic andesites and andesites have higher 87Sr 86Sr, Rb Cs, and Hf Lu, and lower 143Nd 144Nd than basalts and basaltic andesites erupted farther south in the SVZ, which suggests involvement of components derived from the continental crust. In the AVZ, the most primitive sample, high-Mg andesite from the southernmost volcanic center in the Andes (54??S) has Sr and Nd isotopic compositions and K Rb and Ba La similar to MORB. The high La Yb of this sample suggests formation by small degrees of partial melting of subducted MORB with garnet as a residue. Samples from centers farther north in the AVZ show a regionally regular northward increase in SiO2, K2O, Rb, Ba, Ba La, and 87Sr 86Sr and decrease in MgO, Sr, K Rb, Rb Cs, and 143Nd 144Nd, suggesting increasingly greater degrees of fractional crystallization and associated intra-crustal contamination. ?? 1988.

Early Silurian to Early Carboniferous ridge subduction in NW Junggar: Evidence from geochronological, geochemical, and Sr-Nd-Hf isotopic data on alkali granites and adakites

NASA Astrophysics Data System (ADS)

Zhang, Chen; Santosh, M.; Liu, Luofu; Luo, Qun; Zhang, Xin; Liu, Dongdong

2018-02-01

The Central Asian Orogenic Belt (CAOB) evolved through a long-lived orogeny involving multiple episodes of subduction and accretion marking a major phase of continental growth during the Paleozoic. The northern part of the Western Junggar region (NW Junggar) offers a window into these processes, particularly to constrain the timing of closure of the Paleo-Asian Ocean. Here we report geochemical, geochronological, and isotopic data from K-feldspar granites and adakitic rocks from the NW Junggar region. Zircon U-Pb ages suggest that the granites were emplaced during Early Silurian to the Early Carboniferous (434-328 Ma). The granites show geochemical characteristics similar to those of A-type granites, with high SiO2 (71.13-76.72 wt%), Na2O + K2O (8.00-9.59 wt%), and Al2O3 (12.28-14.08 wt%), but depleted Sr, Nb, Ta and Eu. They display moderate to high positive εNd(t) and εHf(t) values (4.26-8.21 and 7.69-14.60, respectively) and young Nd and Hf model ages (T2DM-Nd = 489-740 Ma and T2DM-Hf = 471-845 Ma), suggesting magma derivation through partial melting of lower crust in the Boshchekul-Chingiz and Zharma-Saur arcs. The adakites are characterized by high Sr content (406.5-751.6 ppm), and low Y (13.8-16.4 ppm) and Yb (1.5-1.8 ppm) content, yielding relatively high Sr/Y ratios (25.38-49.41) similar to those of modern adakites. They have high positive εNd(t) and εHf(t) values (7.85-8.25 and 13.23-15.97, respectively) and young Nd and Hf model ages (T2DM-Nd = 429-535 Ma and T2DM-Hf = 355-550 Ma), indicating that their source magmas were likely derived from partial melting of the oceanic crust beneath the Boshchekul-Chingiz arc. The petrogenesis and distribution of the A-type granites and adakites, as well as the tectonic architecture of the region, suggest that a ridge subduction event might have occurred during the Early Silurian to Early Carboniferous. In combination with previous studies in the Chinese Altai, we suggest a two-sided ridge subduction model for the Junggar-Altai region.

Age, geochemical and Sr Nd Pb isotopic constraints for mantle source characteristics and petrogenesis of Teru Volcanics, Northern Kohistan Terrane, Pakistan

NASA Astrophysics Data System (ADS)

Khan, S. D.; Stern, R. J.; Manton, M. I.; Copeland, P.; Kimura, J. I.; Khan, M. A.

2004-11-01

This paper presents new geochemical and geochronology data for the Teru Volcanic Formation (previously known as the Shamran Volcanics) exposed west of Gilgit in the Kohistan terrane of the Pakistani Himalayas. The Teru Volcanic Formation ranges from basalt through andesite to rhyolite and has subalkaline and midalkaline affinities. Trace-element compositions and isotopic characteristics suggest these magmas were formed in a subduction zone setting; isotopic studies also support this conclusion. It is suggested that these lavas originated from a depleted mantle source, which experienced contamination by variable subduction components. Model mixing calculations using 87Sr/ 86Sr and 143Nd/ 144Nd data suggest that addition of 0.2-0.6% of Indus margin sediments and/or 2-4% of fluids derived from Indus margin sediment can generate the compositional variation of the Teru Volcanic Formation. Two samples from the Teru Volcanic Formation yielded 40Ar/ 39Ar ages of 43.8+0.5 and 32.5+0.4 Ma. These ages make the volcanic rocks of the Teru Volcanic Formation the youngest reported in the Kohistan terrane. These volcanic rocks unconformably overly the Shunji Pluton, which has a 65 Ma Rb-Sr whole-rock isochron age. The results of this research suggest that subduction-related volcanism was active until 33 Ma in the India-Asia collision zone.

A combined Sm-Nd, Rb-Sr, and U-Pb isotopic study of Mg-suite norite 78238: Further evidence for early differentiation of the Moon

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

Edmunson, J; E.Borg, L; Nyquist, L E

2008-11-17

Lunar Mg-suite norite 78238 was dated using the Sm-Nd, Rb-Sr, and U-Pb isotopic systems in order to constrain the age of lunar magma ocean solidification and the beginning of Mg-suite magmatism, as well as to provide a direct comparison between the three isotopic systems. The Sm-Nd isotopic system yields a crystallization age for 78238 of 4334 {+-} 37 Ma and an initial {var_epsilon}{sub Nd}{sup 143} value of -0.27 {+-} 0.74. The age-initial {var_epsilon}{sub Nd}{sup 143} (T-I) systematics of a variety of KREEP-rich samples, including 78238 and other Mg-suite rocks, KREEP basalts, and olivine cumulate NWA 773, suggest that lunar differentiationmore » was completed by 4492 {+-} 61 Ma assuming a Chondritic Uniform Reservoir bulk composition for the Moon. The Rb-Sr isotopic systematics of 78238 were disturbed by post-crystallization processes. Nevertheless, selected data points yield two Rb-Sr isochrons. One is concordant with the Sm-Nd crystallization age, 4366 {+-} 53 Ma. The other is 4003 {+-} 95 Ma and is concordant with an Ar-Ar age for 78236. The {sup 207}Pb-{sup 206}Pb age of 4333 {+-} 59 Ma is concordant with the Sm-Nd age. The U-Pb isotopic systematics of 78238 yield linear arrays equivalent to younger ages than the Pb-Pb system, and may reflect fractionation of U and Pb during sample handling. Despite the disturbed nature of the U-Pb systems, a time-averaged {mu} ({sup 238}U/{sup 204}Pb) value of the source can be estimated at 27 {+-} 30 from the Pb-Pb isotopic systematics. Because KREEP-rich samples are likely to be derived from source regions with the highest U/Pb ratios, the relatively low {mu} value calculated for the 78238 source suggests the bulk Moon does not have an exceedingly high {mu} value.« less

Petrogenesis and tectonics of the Acasta Gneiss Complex derived from integrated petrology and 142Nd and 182W extinct nuclide-geochemistry

NASA Astrophysics Data System (ADS)

Reimink, Jesse R.; Chacko, Thomas; Carlson, Richard W.; Shirey, Steven B.; Liu, Jingao; Stern, Richard A.; Bauer, Ann M.; Pearson, D. Graham; Heaman, Larry M.

2018-07-01

The timing and mechanisms of continental crust formation represent major outstanding questions in the Earth sciences. Extinct-nuclide radioactive systems offer the potential to evaluate the temporal relations of a variety of differentiation processes on the early Earth, including crust formation. Here, we investigate the whole-rock 182W/184W and 142Nd/144Nd ratios and zircon Δ17O values of a suite of well-studied and lithologically-homogeneous meta-igneous rocks from the Acasta Gneiss Complex, Northwest Territories, Canada, including the oldest-known zircon-bearing rocks on Earth. In the context of previously published geochemical data and petrogenetic models, the new 142Nd/144Nd data indicate that formation of the Hadean-Eoarchean Acasta crust was ultimately derived from variable sources, both in age and composition. Although 4.02 Ga crust was extracted from a nearly bulk-Earth source, heterogeneous μ142Nd signatures indicate that Eoarchean rocks of the Acasta Gneiss Complex were formed by partial melting of hydrated, Hadean-age mafic crust at depths shallower than the garnet stability field. By ∼3.6 Ga, granodioritic-granitic rocks were formed by partial melting of Archean hydrated mafic crust that was melted at greater depth, well into the garnet stability field. Our 182W results indicate that the sources to the Acasta Gneiss Complex had homogeneous, high-μ182W on the order of +10 ppm-a signature ubiquitous in other Eoarchean terranes. No significant deviation from the terrestrial mass fractionation line was found in the triple oxygen isotope (16O-17O-18O) compositions of Acasta zircons, confirming homogeneous oxygen isotope compositions in Earth's mantle by 4.02 Ga.

Neodymium isotopic variations in Northwest Pacific waters

NASA Astrophysics Data System (ADS)

Amakawa, Hiroshi; Nozaki, Yoshiyuki; Alibo, Dia Sotto; Zhang, Jing; Fukugawa, Kiyotaka; Nagai, Hisao

2004-02-01

Four vertical profiles of the concentration and isotopic composition of Nd in seawater were obtained in the western North Pacific. Two profiles from the Kuroshio Current regime showed congruently that although the Nd concentration increases gradually with depth, its isotopic composition varies significantly with depth depending upon the water mass occupying the water column. The high-salinity Kuroshio waters originating from the North Pacific Tropical Water (NPTW) carry the least radiogenic Nd (ɛ Nd = -7.4 to -8.7) to this region at ˜250 m from the western margin continental shelves, most likely from the East China Sea. The Nd isotopic compositions in the North Pacific Intermediate Water (NPIW) that occurs at 600 to 1000 m in the subtropical region are fairly uniform at ɛ Nd = -3.7. The profile data from the ˜38° to 40°N Kuroshio/Oyashio mixed water region off Sanriku of Honshu, Japan, also suggest that the newest NPIW with ɛ Nd = -3.2 is formed there by the mixing of various source waters, and the radiogenic component of Nd is derived mainly from the Oyashio waters. In the Pacific Deep Water (PDW) below ˜1000 m, the Nd isotopic composition is neither vertically nor horizontally homogeneous, suggesting that it serves as a useful tracer for sluggish deep water circulation as well. Two profiles from the Izu-Ogasawara Trench showed a minimum ɛ Nd value at ˜2000 m, suggesting that there exists a horizontal advective flow in the vicinity of Honshu, Japan. There is some evidence from other chemical properties to support this observation. The waters below 4000 m including those within the trench in the subtropical region have ɛ Nd values of around -5, suggesting that the deep waters are fed from the south along the western boundary, ultimately from the Antarctic Bottom Water (AABW) in the South Pacific. This extends up to ˜40°N along the Japanese Islands. In the subarctic region (>˜42°N), the waters have more radiogenic Nd with ɛ Nd > -4.0 throughout the water column, presumably due to the supply of Nd by weathering in such igneous provinces as the Kuril-Kamchatska-Aleutian Island chain. The lateral inhomogeneity of the Nd isotopic composition in PDW suggests that there may be different circulation and mixing regimes in the North Pacific Basin.

High output power of differently cut Nd:MgO:LiTaO3 CW lasers

NASA Astrophysics Data System (ADS)

Sun, D. H.; Liu, S. D.; Wang, D. Z.; Sang, Y. H.; Kang, X. L.; Liu, H.; Bi, Y.; Yan, B. X.; He, J. L.; Wang, J. Y.

2013-04-01

A high-quality Nd3+ and Mg2+ co-doped LiTaO3 (Nd:MgO:LT) crystal was grown by the Czochralski method. The polarized absorption spectra and fluorescence spectra were studied, and the absorption cross section was calculated by Judd-Ofelt (J-O) theory. The laser performance with different sample cuts of the crystal was investigated for the first time, and it was found that Nd:MgO:LT crystal with different cutting directions (a and c) exhibits different laser properties. By optimizing a partial reflectivity mirror in the laser experimental setting, a high continuous wave output power of 3.58 W was obtained at 1092 and 1076 nm with an optical-to-optical conversion efficiency of 22.78% and slope efficiency of 26.06%. The results indicate that Nd:MgO:LT crystal is a promising candidate for the manufacture of Nd3+ doped periodically poled MgO:LiTaO3 crystal (Nd:PPMgOLT), which should have considerable applications in self-frequency doubling and optical parametric oscillation laser devices.

Synthesis and characterization of Nd3+: Yb3+ co-doped near infrared sensitive fluorapatite nanoparticles as a bioimaging probe

NASA Astrophysics Data System (ADS)

Karthi, S.; Kumar, G. A.; Sardar, D. K.; Santhosh, C.; Girija, E. K.

2018-03-01

Trivalent Nd and Yb co-doped rod shaped hexagonal phase fluorapatite (FAP) nanoparticles of length and width about 32 and 13 nm, respectively were prepared by hydrothermal method and investigated the ability for 980 nm emission via Nd3+ → Yb3+ energy transfer with the objective of utilizing them in biomedical imaging. Nd3+ → Yb3+ energy transfer in FAP was studied as a function of both Nd3+ and Yb3+ concentrations and found that when Yb3+ concentration was 10 mol% the FAP phase has partially turned in to YbPO4 phase. The Yb3+ emission intensity at 980 nm significantly increased up to 5 mol% Yb3+ doping and then reduced drastically for further increase in its concentration. Nd3+ →Yb3+ energy transfer rates were evaluated from the decay curves and found that a transfer rate of 71% for 2 mol% Nd3+ co-doped with 5 mol% Yb3+. The cytocompatibility test with fibroblast like cells using MTT assay revealed that the nanoparticles are compatible with the cells.

Mesoproterozoic orangeites of Karelia (Kostomuksha-Lentiira): evidence for composition of mantle lithosphere

NASA Astrophysics Data System (ADS)

Kargin, Alexey; Nosova, Anna; Larionova, Yulia; Kononova, Voctoria; Borisovskiy, Sergey; Kovalchuk, Elena; Griboedova, Irina

2014-05-01

The 1.23-1.20 Ga old diamondiferous lamproites and orangeites (kimberlites of II group) of the Kostomuksha-Taloveys and the Lentiira-Kuhmo dyke fields intrude the Archaean crust of the Karelian craton, NE of the East European Platform. Mineral (a trend of compositional evolution of mica, presence of carbonate minerals in basis, composition of olivine) and geochemical (major elements, ratio of trace elements, primitive mantle normalized trace elements patterns) characteristics of these rocks suggest an orangeitic rather than lamproitic or lamprophyric nature. The composition of Phl-Ol orangeites suggests intensive processes of fractional crystallization for their melts. Cpx-Phl-Ol orangeites indicate higher intensity of lithospheric mantle assimilation then other orangeitic types. Phl-Carb orangeites of the Taloveys area and Cpx-Phl-Ol one of the Lentiira area are closest to primary melts. The Ol-Phl-Cpx orangeites of the Lentiira area contain three generations of unaltered olivine that vary in composition and origin: a) xenocryst derived from depleted mantle peridotite; b) orangeitic olivine phenocryst and c) and olivine like early stage crystallization of megacryst assemblage or a product of metasomatic interaction between mantle peridotite and protokimberlitic melt. Orangeites of Kostomuksha-Lentiira have low- and medium-radiogenic value of (87Sr/86Sr)1200 that range from 0.7038 to 0.7067. Phl-Carb orangeites of Taloveys have less radiogenic isotopic composition of Nd (eNd -11 ... -12) then Cpx-Phl-Ol and Phl-Ol orangeites of Kostomuksha (eNd -6.9 ... -9.4). The study of Sm-Nd and Rb-Sr isotopic systems suggests that an ancient metasomatic mantle source took part in origin of orangeites. We propose a two-steps model of origin of their source (Kargin et al., 2014): 1) The metasomatic component of mantle source (like as MARID-type veins) formed during Lapland-Kola and/or Svecofennian orogeny events (2.1-1.8 Ga ago). 2) The intrusion of orangeites is comparable by time and geological setting with back-arc extensions (such as magmatism of CSDG) during the first stage of Sveconorwegian orogeny, initial stage of assembly of the supercontinent Rodinia (1.31-1.14 Ga). These back-arc extensions inspired of asthenosphere-derived melts to metasomatic lithospheric mantle and a generation of orangeitic melts. Kargin A.V., Nosova A.A., Larionova Yu.O. et al. Mesoproterozoic orangeites (kimberlites II) of Western Karelia: mineralogical, geochemical and Nd-Sr isotopic-geochemical characteristics // Petrology. 2014. V.2. in press.

A novel Norrie disease pseudoglioma gene mutation, c.-1_2delAAT, responsible for Norrie disease in a Chinese family

PubMed Central

Zhang, Xin-Yu; Jiang, Wei-Ying; Chen, Lu-Ming; Chen, Su-Qin

2013-01-01

AIM To investigate the genetic findings and phenotypic characteristics of a Chinese family with Norrie disease (ND). METHODS Molecular genetic analysis and clinical examinations were performed on a Chinese family with ND. Mutations in the Norrie disease pseudoglioma (NDP) gene were detected by direct sequencing. Haplotypes were constructed and compared with the phenotypes in the family. Evolutionary comparisons and mutant open reading frame (ORF) prediction were also undertaken. RESULTS Two family members with ocular manifestations were diagnosed with ND. No signs of sensorineural hearing loss were observed in either patient, while one of them showed signs of mild mental retardation. A novel heterozygous mutation in the NDP gene, c.-1_2delAAT, was detected in both patients. The mutation and the mutation bearing haplotype co-segregated with the ND phenotype in males and was transmitted from their mothers and/or grandmothers (II:2). The male without ND did not harbor the mutation. The mutation occurred at the highly conserved nucleotides. ORF finder predicted that the mutation would lead to the production of a truncated protein that lacks the first 11 N-terminal amino acids. CONCLUSION A novel mutation, c.-1_2delAAT in the NDP gene, was identified in a Chinese family with ND. This mutation caused ND without obvious sensorineural hearing loss. Mental disorder was found in one but not the other patients. The clinical heterogeneity in the family indicated that other genetic variants and epigenetic factors may also play a role in the disease presentation. PMID:24392318

Mathematical simulation of the thermal diffusion in dentine irradiated with Nd:YAG laser using finite difference method

NASA Astrophysics Data System (ADS)

Moriyama, Eduardo H.; Zangaro, Renato A.; Lobo, Paulo D. d. C.; Villaverde, Antonio G. J. B.; Watanabe-Sei, Ii; Pacheco, Marcos T. T.; Otsuka, Daniel K.

2002-06-01

Thermal damage in dental pulp during Nd:YAG laser irradiation have been studied by several researchers; but due to dentin inhomogeneous structure, laser interaction with dentin in the hypersensitivity treatment are not fully understood. In this work, heat distribution profile on human dentine samples irradiated with Nd:YAG laser was simulated at surface and subjacent layers. Calculations were carried out using the Crank-Nicolson's finite difference method. Sixteen dentin samples with 1,5 mm of thickness were evenly distributed into four groups and irradiated with Nd:YAG laser pulses, according to the following scheme: (I) 1 pulse of 900 mJ, (II) 2 pulses of 450 mJ, (III) 3 pulses of 300 mJ, (IV) 6 pulses of 150 mJ; corresponding to a total laser energy of 900 mJ. The pulse interval was 300ms, the pulse duration of 900 ms and irradiated surface area of 0,005 mm2. Laser induced morphological changes in dentin were observed for all the irradiated samples. The heat distribution throughout the dentin layer, from the external dentin surface to the pulpal chamber wall, was calculated for each case, in order to obtain further information about the pulsed Nd:YAG laser-oral hard tissue interaction. The simulation showed significant differences in the final temperature at the pulpal chamber, depending on the exposition time and the energy contained in the laser pulse.

Integrating care for neurodevelopmental disorders by unpacking control: A grounded theory study

PubMed Central

Waxegård, Gustaf; Thulesius, Hans

2016-01-01

Background To establish integrated healthcare pathways for patients with neurodevelopmental disorders (ND) such as autism spectrum disorder and attention-deficit hyperactivity disorder is challenging. This study sets out to investigate the main concerns for healthcare professionals when integrating ND care pathways and how they resolve these concerns. Methods Using classic grounded theory (Glaser), we analysed efforts to improve and integrate an ND care pathway for children and youth in a Swedish region over a period of 6 years. Data from 42 individual interviews with a range of ND professionals, nine group interviews with healthcare teams, participant observation, a 2-day dialogue conference, focus group meetings, regional media coverage, and reports from other Swedish regional ND projects were analysed. Results The main concern for participants was to deal with overwhelming ND complexity by unpacking control, which is control over strategies to define patients’ status and needs. Unpacking control is key to the professionals’ strivings to expand constructive life space for patients, to squeeze health care to reach available care goals, to promote professional ideologies, and to uphold workplace integrity. Control-seeking behaviour in relation to ND unpacking is ubiquitous and complicates integration of ND care pathways. Conclusions The Unpacking control theory expands central aspects of professions theory and may help to improve ND care development. PMID:27609793

Dissolved Pesticide and Organic Carbon Concentrations Detected in Surface Waters, Northern Central Valley, California, 2001-2002

DTIC Science & Technology

2004-01-01

Date (mm/dd/yy) Time Metolachlor Molinate Napro- pamide Oxyfluorfen Pendi- methalin Piperonyl butoxide Simazine Thiobencarb Trifluralin 01/04/01 0910...Metolachlor Molinate Napro- pamide Oxyfluorfen Pendi- methalin Piperonyl butoxide Simazine Thiobencarb Trifluralin 01/04/01 1015 7.8 14.8 nd nd nd 22.2 nd 8.6...Metolachlor Molinate Napropamide Oxyfluorfen Pendimethalin Piperonyl butoxide Simazine Trifluralin 01/04/01 1200 nd 16.2 nd nd nd nd 43.2 nd 01/09/01

Neodymium isotope heterogeneity of ordinary and carbonaceous chondrites and the origin of non-chondritic 142Nd compositions in the Earth

NASA Astrophysics Data System (ADS)

Fukai, Ryota; Yokoyama, Tetsuya

2017-09-01

We present high-precision Nd isotope compositions for ordinary and carbonaceous chondrites determined using thermal ionization mass spectrometry with dynamic and multistatic methods. The ordinary chondrites had uniform and non-terrestrial μ142 Nd , μ148 Nd , and μ150 Nd values, with data that plot along the mixing line between s-process and terrestrial components in μ150 Nd versus μ148 Nd and μ142 Nd versus μ148,150Nd diagrams. In contrast, the carbonaceous chondrites were characterized by larger anomalies in their μ142 Nd , μ148 Nd , and μ150 Nd values compared to ordinary chondrites. Importantly, the data for carbonaceous chondrites plot along the s-process and terrestrial mixing line in a μ150 Nd versus μ148 Nd diagram, whereas they have systematically lower μ142 Nd values than the s-process and terrestrial mixing line in μ142 Nd versus μ148,150Nd diagrams. This shift likely results from the incorporation of calcium- and aluminum-rich inclusions (CAIs), indicating that the Nd isotopic variability in the ordinary chondrites and CAI-free carbonaceous chondrites was caused solely by the heterogeneous distribution of s-process nuclides. The isotopic variation most likely results from nebular thermal processing that caused selective destruction of s-process-depleted (or r-process-enriched) dust grains in the inner Solar System where the parent bodies of ordinary chondrites formed, whereas such grains were preserved in the region of carbonaceous chondrite parent body formation. The Nd isotope dichotomy between ordinary and bulk aliquots of carbonaceous chondrites can be related to the presence of Jupiter, which may have separated two isotopically distinct reservoirs that were present in the solar nebula. After correcting for s-process anomalies and CAI contributions to the Nd isotopes observed in the chondrites, we obtained a μ142 Nd value (- 2.4 ± 4.8 ppm) that was indistinguishable from the terrestrial value. Our results corroborate the interpretation that a missing reservoir (e.g., a hidden enriched reservoir, erosional loss of crust) is not required to explain the observed differences in 142Nd/144Nd ratios between chondrites and terrestrial materials.

Evaluation of Salivary Profile among Adult Type 2 Diabetes Mellitus Patients in South India

PubMed Central

K.M, Prathibha; Johnson, Priscilla; Ganesh, Mathangi; Subhashini, Arcot S.

2013-01-01

Background: A lack of consensus on the possible association between diabetes and salivary dysfunction motivated us to conduct this investigation on the salivary parameters in diabetic and non diabetic subjects. This could also make the use of saliva as an alternative to that of blood in the diagnosis/monitoring of diabetes mellitus. Objectives: To compare the salivary flow rates and the salivary physical and biochemical parameters of diabetic (D) and non diabetic (ND) subjects. Material and Methods: The participants in this study included 30 non diabetic subjects and 30 diabetic volunteers who had Type 2 Diabetes mellitus for a minimum of 2 years. Unstimulated whole saliva was collected in the fasting state. Salivary pH, flow rate and organic and inorganic constituents were evaluated. Data which was collected was statistically analysed and interpreted. Results: Salivary pH (ND=7.09±0.29, D=6.69±0.35), flow rate (ND=0.67±0.07, D=0.46±0.02) and salivary amylase (ND=92.51±13.74, D=19.20±1.8) were significantly lower in diabetics. They had significantly higher levels of salivary glucose (ND=4.33 ± 0.29, D=17.31±2.05), total proteins (ND=424.46±237.34, D=877.29±603.84), sodium (ND=4.31±0.65, D=14.42±1.83) and potassium (ND=20.84±0.71, D=25.95±1.56) and lower levels of calcium (ND=6.39±0.5, D=4.22±0.12) in comparison to those in the non-diabetic group. Conclusion: Significant variations were observed in salivary physical and biochemical parameters between diabetics and non diabetics. Evaluation of salivary parameters can be a cost effective and a non invasive alternative for screening, diagnosis and monitoring of diabetes, to blood. PMID:24086848

Characterization of pulsed (plasma focus) neutron source with image plate and application to neutron radiography

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

Andola, Sanjay; Niranjan, Ram; Rout, R. K.

Plasma focus device of Mather type developed in house has been used first time for neutron radiography of different objects. The device gives (1.2{+-}0.3) Multiplication-Sign 10{sup 9} neutrons per pulse produced by D-D fusion reaction with a pulse width of 50{+-}5 ns. The method involves exposing sample to be radiographed to thermalized D-D neutrons and recording the image on Fuji-film BAS-ND image plates. The thermal neutron component of the moderated beam was estimated using two image plates: a conventional IP for X-rays and gamma rays, and an IP doped with Gd for detecting neutrons.

Selective attention to sound location or pitch studied with event-related brain potentials and magnetic fields.

PubMed

Degerman, Alexander; Rinne, Teemu; Särkkä, Anna-Kaisa; Salmi, Juha; Alho, Kimmo

2008-06-01

Event-related brain potentials (ERPs) and magnetic fields (ERFs) were used to compare brain activity associated with selective attention to sound location or pitch in humans. Sixteen healthy adults participated in the ERP experiment, and 11 adults in the ERF experiment. In different conditions, the participants focused their attention on a designated sound location or pitch, or pictures presented on a screen, in order to detect target sounds or pictures among the attended stimuli. In the Attend Location condition, the location of sounds varied randomly (left or right), while their pitch (high or low) was kept constant. In the Attend Pitch condition, sounds of varying pitch (high or low) were presented at a constant location (left or right). Consistent with previous ERP results, selective attention to either sound feature produced a negative difference (Nd) between ERPs to attended and unattended sounds. In addition, ERPs showed a more posterior scalp distribution for the location-related Nd than for the pitch-related Nd, suggesting partially different generators for these Nds. The ERF source analyses found no source distribution differences between the pitch-related Ndm (the magnetic counterpart of the Nd) and location-related Ndm in the superior temporal cortex (STC), where the main sources of the Ndm effects are thought to be located. Thus, the ERP scalp distribution differences between the location-related and pitch-related Nd effects may have been caused by activity of areas outside the STC, perhaps in the inferior parietal regions.

An Archaean Tonalite-Trondhjemite-Granodiorite Association of the Kursk Block (Voronezh Massif): Composition, Age, and Correlation with the Ukrainian Shield

NASA Astrophysics Data System (ADS)

Savko, K. A.; Samsonov, A. V.; Larionov, A. N.; Korish, E. Kh.; Bazikov, N. S.

2018-01-01

Framing of the Archaean greenstone belts of the Kursk Block (KB) of the East Sarmatia preserves rocks of the TTG association: those do not form massifs with distinct boundaries, but occur as fields gradually transiting into gneisses and migmatites. According to Sm-Nd isotope-geochemical data, the TTG are characterized by positive values of ɛNd(2960) = +0.3…+1.6 and protolith model ages of T Nd( DM) = 3100-3200 Ma. Magmatic protoliths of the Kursk Block TTG were formed about 2960 Ma by melting from a juvenile basite source. These age estimates are significantly younger than heterochronous (3.19, 3.13 and 3.07 Ga) TTGs of the Middle Dnieper granite-greenstone terrane. On the other hand, the similarity of ɛNd(T) implies a single source of their protoliths. Consequently, the KB TTGs, apparently, are a result of transformation of an older sial crust preserved within the Middle Dnieper Block.

Growth of continental crust: Clues from Nd isotopes and Nb-Th relationships in mantle-derived magmas

NASA Astrophysics Data System (ADS)

Arndt, N. T.; Chauvel, C.; Jochum, K.-P.; Gruau, G.; Hofmann, A. W.

Isotope and trace element geochemistry of Precambrian mantle derived rocks and implications for the formation of the continental crust is discussed. Epsilon Nd values of Archean komatiites are variable, but range up to at least +5, suggesting that the Archean mantle was heterogeneous and, in part, very depleted as far back as 3.4 to 3.5 Ga. This may be taken as evidence for separation of continental crust very early in Earth history. If these komatiite sources were allowed to evolve in a closed system, they would produce modern day reservoirs with much higher epsilon Nd values than is observed. This implies recycling of some sort of enriched material, perhaps subducted sediments, although other possibilities exist. Archean volcanics show lower Nb/Th than modern volcanics, suggesting a more primitive mantle source than that observed nowadays. However, Cretaceous komatiites from Gorgona island have similar Nb/Th to Archean volcanics, indicating either the Archean mantle source was indeed more primitive, or Archean magmas were derived from a deep ocean island source like that proposed for Gorgona.

Growth of continental crust: Clues from Nd isotopes and Nb-Th relationships in mantle-derived magmas

NASA Technical Reports Server (NTRS)

Arndt, N. T.; Chauvel, C.; Jochum, K.-P.; Gruau, G.; Hofmann, A. W.

1988-01-01

Isotope and trace element geochemistry of Precambrian mantle derived rocks and implications for the formation of the continental crust is discussed. Epsilon Nd values of Archean komatiites are variable, but range up to at least +5, suggesting that the Archean mantle was heterogeneous and, in part, very depleted as far back as 3.4 to 3.5 Ga. This may be taken as evidence for separation of continental crust very early in Earth history. If these komatiite sources were allowed to evolve in a closed system, they would produce modern day reservoirs with much higher epsilon Nd values than is observed. This implies recycling of some sort of enriched material, perhaps subducted sediments, although other possibilities exist. Archean volcanics show lower Nb/Th than modern volcanics, suggesting a more primitive mantle source than that observed nowadays. However, Cretaceous komatiites from Gorgona island have similar Nb/Th to Archean volcanics, indicating either the Archean mantle source was indeed more primitive, or Archean magmas were derived from a deep ocean island source like that proposed for Gorgona.

Crystalline perfection and optical studies of L-Histidinium dihydrogen phosphate orthophosphoric acid (LHDP) single crystals

NASA Astrophysics Data System (ADS)

Ittyachan, Reena; Arunkumar, A.; Bhagavannarayana, G.

2015-10-01

Single crystals of L-Histidinium dihydrogenphosphate orthophosphoric acid (LHDP) were grown by slow evaporation solution growth technique. The grown crystals were confirmed by single crystal X-ray diffraction techniques. The HRXRD rocking curve measurements revealed the crystalline perfection of grown crystal and the absence of structural grain boundaries. The lower optical cut-off wavelength for this crystal was observed at 240 nm. The third order nonlinear refractive index (n2), nonlinear absorption coefficient (β) and susceptibility (χ(3)) were calculated by Z-scan studies using Nd: YAG laser as a source. The single shot laser damage threshold of grown crystal was measured to be 6.286 GW/cm2 using Nd: YAG laser.

High Power Microwaves on the Future Battlefield: Implications for U.S. Defense

DTIC Science & Technology

2010-02-17

Group, 2007), Chapters 7-10, and Steven H. Gold, Gregory S . Nusinovich, “Review of High - Power Microwave Source Research,” Review of Scientific...Edl Schamiloglu. High Power Microwaves. 2nd ed. Boca Raton, FL: CRC Press, Taylor and Francis Group, 2007. Bertin, Michael S . “Critical Directed...Gold, Steven H., Gregory S . Nusinovich. “Review of High - Power Microwave Source Research.” Review of Scientific Instruments 68, no. 11 (November

Judd-Ofelt Parameters via Bayesian Inference

NASA Astrophysics Data System (ADS)

Silva, Valdeir A.; Silva, José W.; de Morais, Paulo C.; Dantas, Noelio O.

2018-04-01

Bayesian inference was used as a new approach to calculate of rare earth (RE) ion spectroscopic parameters within the Judd-Ofelt theory using the Li2O-B2O3-Al2O3 glass system doped with Nd2O3 and TiO2. This system was synthesized by the fusion method, and the physical properties of the as-synthesized material were investigated. Optical absorption, photoluminescence, micro-Raman, mass density, refractive index, and radiative lifetime calcuations were performed. We investigated the effects of crystal field changes on Nd3+-ions caused due to co-doping with increasing TiO2 content. We observed that co-doping with TiO2 altered the radiative transition rates A( J, J '), favored symmetry enhancement around the Nd3+-ions, and promoted the onset of vibrational modes, contributed to the attenuation of O-H bonds, and substantially increased the spectroscopic quality, χ.

Estimating the Submarine Groundwater Discharge Flux of Rare Earth Elements to the Indian River Lagoon, Fl, USA, Using the 1-D Vertical - Flow Equation

NASA Astrophysics Data System (ADS)

Chevis, D. A.; Johannesson, K. H.; Burdige, D.; Cable, J. E.; Martin, J. B.

2013-12-01

Understanding the sources and sinks of trace elements like the rare earth elements (REE) in the oceans has important implications for quantifying their global geochemical cycles, their application as paleoceanographic tracers, and in discerning the geochemical reactions that mobilize, sequester, and fractionate REEs in the environment. This understanding is critical for neodymium (Nd) because radiogenic Nd isotopes are commonly used in paleoceanographic studies over glacial-interglacial to million year time scales. The submarine groundwater discharge (SGD) flux of each REE for the Indian River Lagoon, Fl, USA, was calculated using a modified form of the 1-dimensional vertical-flow equation that accounts for diffusion, advection, and non-local mass transfer processes. The SGD REE flux is comprised of two sources: a near shore, heavy REE (HREE) enriched advective source chiefly composed of terrestrial SGD, and a light REE (LREE) and middle REE (MREE) enriched source that originates from reductive dissolution of Fe (III) oxides/hydroxides in the subterranean estuary. This SGD flux mixture of REE sources is subsequently transported by groundwater seepage and bioirrigation to the overlying lagoon water column. The total SGD flux of REEs reveals that the subterranean estuary of the Indian River Lagoon is a source for LREE and MREEs, and a sink for the HREEs, to the local coastal ocean. The calculated SGD flux of Nd presented in this study is estimated at 7.69×1.02 mmol/day, which is roughly equivalent to the effective local river flux to the Indian River Lagoon. Although our re-evaluated SGD flux of Nd to the Indian River Lagoon is lower than estimates in our previous work, it nonetheless represents a substantial input to the coastal ocean.

Near-infrared photoluminescence in La0.98AlO3: 0.02Ln3+(Ln = Nd/Yb) for sensitization of c-Si solar cells

NASA Astrophysics Data System (ADS)

Sawala, N. S.; Koparkar, K. A.; Bajaj, N. S.; Omanwar, S. K.

2016-05-01

The host matrix LaAlO3 was synthesized by conventional solid state reaction method in which the Nd3+ ions and Yb3+ ions successfully doped at 2mol% concentrations. The phase purity was confirmed by X ray powder diffraction (XRD) method. The photoluminescence (PL) properties were studied by spectrophotometer in near infra red (NIR) and ultra violet visible (UV-VIS) region. The Nd3+ ion doped LaAlO3 converts a visible (VIS) green photon (587 nm) into near infrared (NIR) photon (1070 nm) while Yb3+ ion doped converts ultra violet (UV) photon (221 nm) into NIR photon (980 nm). The La0.98AlO3: 0.02Ln3+(Ln = Nd / Yb) can be potentiality used for betterment of photovoltaic (PV) technology. This result further indicates its potential application as a luminescence converter layer for enhancing solar cells performance.

Constant Chinese Loess Plateau dust source since the Late Miocene

NASA Astrophysics Data System (ADS)

Bird, Anna; Millar, Ian; Stevens, Thomas; Rodenburg, Tanja; Rittner, Martin; Vermeesch, Pieter; Lu, Huayu

2017-04-01

The dramatic deepening of northern hemisphere glaciation at the Pliocene-Pleistocene boundary is accompanied by major changes in global climate. The role of the global atmospheric dust cycle in this event is not clear; in particular, whether, changes in the dust cycle influenced climates change, or resulted from it. Miocene and Quaternary wind-blown Chinese loess records past dust-cycle history, influences of aridification and monsoon circulation. Previous work on the vast Chinese Loess Plateau is in conflict over whether changes in dust source occur at the Pliocene-Pleistocene boundary (2.59 Ma), or at 1.2 Ma, despite these intervals marking major shifts in monsoon dynamics (Sun 2005; Nie et al. 2014a). Here we present Sr, Nd and Hf isotopic data from multiple sites and show that the dust source remains the same across these boundaries. The use of isotope tracers from multiple sites allows us to demonstrate that shifts in sediment geochemistry can be explained by grain-size and weathering changes. Nd and Hf isotopes show that the dust was dominantly sourced from the Tibetan Plateau, with some input from bedrock underlying the Badain Jaran/Tengger deserts. This shows that a major established and constant dust source on the northern Tibetan Plateau has been active and unchanged since the late Miocene, despite dramatically changing climate conditions. Changes in loess accumulation are therefore a function of climate change in the Tibetan Plateau source regions rather than due to expanding source areas controlled by aridification over a widening area over the Pliocene and Quaternary.

Evaluation of the photocatalytic activity of Ln3+-TiO2 nanomaterial using fluorescence technique for real wastewater treatment.

PubMed

Saif, M; Aboul-Fotouh, S M K; El-Molla, S A; Ibrahim, M M; Ismail, L F M

2014-07-15

Evaluation the photocatalytic activity of different Ln(3+) modified TiO2 nanomaterials using fluorescence based technique has rarely been reported. In the present work, xmol Ln(3+) modified TiO2 nanomaterials (Ln = Nd(3+), Sm(3+), Eu(3+), Gd(3+), Dy(3+) and Er(3+) ions; x = 0.005, 0.008, 0.01, 0.02 and 0.03) were synthesized by sol-gel method and characterized using different advanced techniques. The photocatalytic efficiency of the modified TiO2 expressed in the charge carrier separation and OH radicals formation were assigned using TiO2 fluorescence quenching and fluorescence probe methods, respectively. The obtained fluorescence measurements confirm that doping treatment significantly decreases the electron-hole recombination probability in the obtained Ln(3+)/TiO2. Moreover, the rate of OH radicals formation is increased by doping. The highly active nanoparticles (0.02Gd(3+)/TiO2 and 0.01Eu(3+)/TiO2) were applied for industrial wastewater treatment using solar radiation as a renewable energy source. Copyright © 2014 Elsevier B.V. All rights reserved.

Effectiveness Leadership of Principal

ERIC Educational Resources Information Center

Kempa, Rudolf; Ulorlo, Marthen; Wenno, Izaak Hendrik

2017-01-01

Effective principal leadership is a leadership that can foster cooperative efforts and maintain an ideal working climate in schools. The purpose of this research is to know the effectiveness leadership of the principal of the 2nd State Junior High School of Ambon, with qualitative approach. Data sources include school principals, vice principals,…

Development of a two photon/laser induced fluorescence technique for the detection of atmospheric OH radicals

NASA Technical Reports Server (NTRS)

Bradshaw, John

1990-01-01

The development of a new mid-IR laser source was the primary goal. Backward propagating stimulated D2 Raman frequency down conversion of a commercially available 1.06 micron Nd:YAG laser was shown to generate an efficient source of 1.56 micron radiation with near diffraction limited beam quality. The efficient generation of a 2.9 micron laser source was also achieved using backward propagating CH4 Raman frequency down conversion of the 1.56 micron pump. Slightly higher efficiencies were obtained for frequency down conversion of the 1.06 micron Nd:YAG using the H2 Raman shift yielding a near diffraction limited source in the 200 mJ range at 1.9 micron. Similar conversion efficiencies are anticipated as a result of extending the wavelength coverage of recently available Ti:sapphire pulse laser to not only cover the 740 to 860 nm fundamental wavelength range but also the .95 to 1.15 and 1.06 to 1.33 micron range using D2 and H2, respectively. The anticipated sensitivity of a TP-LIF OH sensor using this mid-IR source would give signal limited detection of 1.4 x 10(exp 5) OH/cu cm under boundary layer conditions and 5.5 x 10(exp 4) OH/cu cm under free troposphere sampling conditions for a five minute signal integration period. This level of performance coupled with the techniques non-perturbing nature and freedom from both interferences and background would allow reliable tropospheric OH measurement to be obtained under virtually any ambient condition of current interest, including interstitial and sampling.

Ab initio molecular dynamics simulations of ion-solid interactions in zirconate pyrochlores

DOE PAGES

Xiao, Haiyan Y.; Weber, William J.; Zhang, Yanwen; ...

2015-01-31

In this paper, an ab initio molecular dynamics method is employed to study low energy recoil events in zirconate pyrochlores (A 2Zr 2O 7, A = La, Nd and Sm). It shows that both cations and anions in Nd 2Zr 2O 7 and Sm 2Zr 2O 7 are generally more likely to be displaced than those in La 2Zr 2O 7. The damage end states mainly consist of Frenkel pair defects, and the Frenkel pair formation energies in Nd 2Zr 2O 7 and Sm 2Zr 2O 7 are lower than those in La 2Zr 2O 7. These results suggest thatmore » the order–disorder structural transition more easily occurs in Nd 2Zr 2O 7 and Sm 2Zr 2O 7 resulting in a defect-fluorite structure, which agrees well with experimental observations. Our calculations indicate that oxygen migration from 48f and 8b to 8a sites is dominant under low energy irradiation. A number of new defects, including four types of cation Frenkel pairs and six types of anion Frenkel pairs, are revealed by ab initio molecular dynamics simulations. The present findings may help to advance the fundamental understanding of the irradiation response behavior of zirconate pyrochlores.« less

Chronologic implications for slow cooling of troctolite 76535 and temporal relationships between the Mg-suite and the ferroan anorthosite suite

NASA Astrophysics Data System (ADS)

Borg, Lars E.; Connelly, James N.; Cassata, William S.; Gaffney, Amy M.; Bizzarro, Martin

2017-03-01

Ages have been obtained using the 87Rb-87Sr, 147Sm-143Nd, and 146Sm-142Nd isotopic systems for one of the most slowly cooled lunar rocks, Apollo 17 Mg-suite troctolite 76535. The 147Sm-143Nd, 146Sm-142Nd, and Rb-Sr ages derived from plagioclase, olivine, and pyroxene mineral isochrons yield concordant ages of 4307 ± 11 Ma, 4299+29/-35 Ma, and 4279 ± 52 Ma, respectively. These ages are slightly younger than the age determined on ferroan anorthosite suite (FAS) rock 60025 and are therefore consistent with the traditional magma ocean model of lunar differentiation in which the Mg-suite is intruded into the anorthositic crust. However, the Sm-Nd ages record when the rock passed below the closing temperature of the Sm-Nd system in this rock at ∼825 °C, whereas the Rb-Sr age likely records the closure temperature of ∼650 °C. A cooling rate of 3.9 °C/Ma is determined using the ages reported here and in the literature and calculated closure temperatures for the Ar-Ar, Pb-Pb, Rb-Sr, and Sm-Nd systems. This cooling rate is in good agreement with cooling rates estimated from petrographic observations. Slow cooling can lower apparent Sm-Nd crystallization ages by up to ∼80 Ma in the slowest cooled rocks like 76535, and likely accounts for some of the variation of ages reported for lunar crustal rocks. Nevertheless, slow cooling cannot account for the overlap in FAS and Mg-suite rock ages. Instead, this overlap appears to reflect the concordance of Mg-suite and FAS magmatism in the lunar crust as indicated by ages calculated for the solidus temperature of 76535 and 60025 of 4384 ± 24 Ma and 4383 ± 17, respectively. Not only are the solidus ages of 76535 and 60025 nearly concordant, but the Sm-Nd isotopic systematics suggest they are derived from reservoirs that were minimally differentiated prior to ∼4.38 Ga. Although the Sr isotopic composition of 60025 indicates its source was minimally differentiated, the Sr isotopic composition of 76535 indicates it underwent fractionation just prior to solidification of the 76535. These observations are consistent with both a magma ocean or a serial magmatism model of lunar differentiation. In either model, differentiation of lunar source regions must occur near the solidification age of thee samples. Perhaps the best estimate for the formation age of lunar source regions is the Rb-Sr model age of the 76535 source region age of 4401 ± 32 Ma. This is in good agreement with Sm-Nd model ages for the formation of ur-KREEP and suggests that differentiation of a least part of the Moon could not have occurred prior to ∼4.43 Ga.

A major change in North Atlantic deep water circulation 1.6 million years ago

NASA Astrophysics Data System (ADS)

Khélifi, N.; Frank, M.

2014-07-01

The global ocean-climate system has been highly sensitive to the formation and advection of deep overflow water from the Nordic Seas as integral part of the Atlantic Meridional Overturning Circulation (AMOC) but its evolution over the Pliocene-Pleistocene global cooling is not fully understood. In particular, changes in the sources and mixing of prevailing deep waters that were involved in driving overturning throughout the Pliocene-Pleistocene climate transitions are not well constrained. Here we investigate the evolution of a substantial deep southward return overflow of the AMOC over the last 4 million years. We present new records of the bottom-water radiogenic neodymium isotope (ϵNd) variability obtained from three sediment cores (DSDP site 610 and ODP sites 980/981 and 900) at water depths between 2170 and 5050 m in the northeast Atlantic. We find that prior to the onset of major Northern Hemisphere glaciation (NHG) ∼3 million years ago (Ma), ϵNd values primarily oscillated between -9 and -11 at all sites, consistent with enhanced vertical mixing and weak stratification of the water masses during the warmer-than-today Pliocene period. From 2.7 Ma to ∼2.0 Ma, the ϵNd signatures of the water masses gradually became more distinct, which documents a significant advection of Nordic Seas overflow deep water coincident with the intensification of NHG. Most markedly, however, at ∼1.6 Ma the interglacial ϵNd signatures at sites 610 (2420 m water depth (w.d.)) and 980/981 (2170 m w.d.) synchronously and permanently shifted by 2 to 3 ϵNd units to less radiogenic values, respectively. Since then the difference between glacial and interglacial ϵNd values has been similar to the Late Quaternary at each site. A decrease of ∼2ϵNd units at 1.6 Ma was also recorded for the deepest water masses by site 900 (∼5050 m w.d.), which thereafter, however, evolved to more radiogenic values again until the present. This major ϵNd change across the 1.6 Ma transition reflects a significant reorganization of the overturning circulation in the northeast Atlantic paving the way for the more stratified water column with distinct water masses prevailing thereafter.

Impact of Nd3+ ions on physical and optical properties of Lithium Magnesium Borate glass

NASA Astrophysics Data System (ADS)

Mhareb, M. H. A.; Hashim, S.; Ghoshal, S. K.; Alajerami, Y. S. M.; Saleh, M. A.; Dawaud, R. S.; Razak, N. A. B.; Azizan, S. A. B.

2014-11-01

Enhancing the up-conversion efficiency of borate glass via optimized doping of rare earth ions is an ever-ending quest in lasing glass. Neodymium (Nd3+) doped Lithium Magnesium Borate (LMB) glasses are prepared using the melt-quenching method. X-ray diffraction (XRD), Fourier transformed infrared (FTIR), UV-Vis-NIR absorption and Photoluminescence (PL) spectroscopic characterizations are made to examine the influence of Nd3+ concentration on physical properties and optical properties. Nd3+ contents dependent density, molar volume, refractive index, ion concentration, Polaron radius, inter nuclear distance, field strength, energy band gap and oscillator strength are calculated. XRD patterns confirm the amorphous nature of all glasses and the FTIR spectra reveal the presence of BO3 and BO4 functional groups. UV-Vis-IR spectra exhibit ten prominent bands centered at 871, 799, 741, 677, 625, 580, 522, 468, 426, 349 nm corresponding to the transitions from the ground state to 4F3/2, (4F5/2 + 2H9/2), (4F7/2 + 4S3/2), 4F9/2, 2H11/2, (4G5/2 + 2G7/2), (2K13/2 + 4G7/2 + 4G9/2), (2G9/2 + 2D3/2 + 2P3/2), (2P1/2 + 2D5/2), (4D3/2 + 4D5/2) excited states, respectively. A hyper-sensitive transition related to (4G5/2 + 2G7/2) level is evidenced at 580 nm. The room temperature up-conversion emission spectra at 800 nm excitation displays three peaks centered at 660, 610 and 540 nm. Glass with 0.5 mol% of Nd3+ showing an emission enhancement by a factor to two is attributed to the energy transfer between Mg2+ and Nd3+ ions. Our results suggest that these glasses can be nominated for solid state lasers and other photonic devices.

Neutron investigation of Nd 2- x- yCe xLa yCuO 4 (0 ⩽ x ⩽ 0.2; y = 0.5, 1)

NASA Astrophysics Data System (ADS)

Gutmann, M.; Allenspach, P.; Fauth, F.; Furrer, A.; Zolliker, M.; Rosenkranz, S.; Eccleston, R. S.

1997-02-01

We present neutron diffraction and crystal field (CF) spectroscopy results obtained for the electron-doped superconductor precursor material Nd 2- x- yCe xLa yCuO 4 (0 ⩽ x ⩽ 0.2; y = 0.5, 1). Samples were prepared via a sol-gel methods. The lattice constants as a function of Ce-doping show the well-known behavior common to this class of compounds, i.e. the a parameter increases while the c parameter decreases with increasing Ce amount. The presence of La expands the unit cell in all directions compared to the mother compound Nd 2CuO 4 while preserving the T‧-structure for the above mentioned range. The CF spectra clearly show the presence of electronic inhomogeneities associated with electron doping from Ce 4+ on one Cu-site in the CuO 2-planes.

Ab initio calculation of electronic structure and magnetic properties of R2Fe14BNx (R = Pr,Nd)

NASA Astrophysics Data System (ADS)

Tian, Guang; Zha, Liang; Yang, Wenyun; Qiao, Guanyi; Wang, Changsheng; Yang, Yingchang; Yang, Jinbo

2018-05-01

The site preference of N atom for R2Fe14BNx (R= Pr, Nd) and the interstitial nitrogen effect on the magnetic properties have been studied by the first-principles method. It was found that the nitrogen is more likely to occupy the 4e site for Pr2Fe14BNx compound, while 4f site for Nd2Fe14BNx. When N atoms entering some specific crystal sites (such as 2a and 4f), the total magnetic moments of these compounds are not reduced, but slightly increased. Although the doping of N may reduce the total magnetic moments of some R2Fe14B compounds in the cases of optimal occupancy, the volumetric effect caused by N doping can still change the electron density distributions of Fe near the Fermi level, improving the magnetic ordering temperature of such compounds.

The U-Th-Pb, Sm-Nd, and Ar-Ar isotopic systematics of lunar meteorite Yamato-793169

NASA Technical Reports Server (NTRS)

Torigoye, Noriko; Misawa, Keji; Dalrymple, G. Brent; Tatsumoto, Mitsunobu

1993-01-01

U-Th-Pb, Sm-Nd, and (Ar-40)-(Ar-39) isotopic studies were performed on Yamato (Y)-793169, an unbrecciated diabasic lunar meteorite whose chemical composition is close to low Ti(LT) and very low-Ti (VLT) mare basalts. The isotopic data indicate that the meteorite was formed earlier than 3.9 Ga from a source with low U/Pb and high Sm/Nd and was distributed by a thermal event at 751 Ma. due to the small sample size (104 mg), a plagioclase crystal and glass grains were handpicked for Ar analysis, leaving four fractions for the U-Th-Pb and Sm-Nd studies; a fine-grained fraction (less than 63 microns; Fine) and three medium-grained fractions (63-150 microns). Medium-grained fractions were divided by density; a heavy fraction (rho greater than 3.3) consisting mainly of pyroxene (PX1), a lighter fraction (rho less than 2.8) consisting of plagioclase (PL), and a middle density fraction (predominantly pyroxene; PX2). The fractions were washed with acetone and alcohol, and then leached in 0.01 HBr and 0.1N HBr in order to remove any terrestrial Pb contamination. Analysis of the HBr leaches revealed that this meteorite was heavily contaminated with terrestrial Pb during its residence in Antarctic ice.

Thermodynamic Studies on NdFeO 3(s)

NASA Astrophysics Data System (ADS)

Parida, S. C.; Dash, Smruti; Singh, Ziley; Prasad, R.; Jacob, K. T.; Venugopal, V.

2002-02-01

The enthalpy increments and the standard molar Gibbs energy of formation of NdFeO3(s) have been measured using a high-temperature Calvet microcalorimeter and a solid oxide galvanic cell, respectively. A λ-type transition, related to magnetic order-disorder transformation (antiferromagnetic to paramagnetic), is apparent from the heat capacity data at ∼687 K. Enthalpy increments, except in the vicinity of transition, can be represented by a polynomial expression: {H°m(T)-H°m(298.15 K)}/J·mol-1 (±0.7%)=-53625.6+146.0(T/K) +1.150×10-4(T/K)2 +3.007×106(T/K)-1; (298.15≤T/K ≤1000). The heat capacity, the first differential of {H°m(T)-H°m(298.15 K)} with respect to temperature, is given by Cop, m/J·K-1·mol-1=146.0+2.30×10-4(T/K)-3.007×106(T/K)-2. The reversible emf's of the cell, (-) Pt/{NdFeO3(s) +Nd2O3(s)+Fe(s)}//YDT/CSZ//{Fe(s)'FeO'(s)}/Pt(+), were measured in the temperature range from 1004 to 1208 K. It can be represented within experimental error by a linear equation: E/V:(0.1418±0.0003)-(3.890±0.023)×10-5(T/K). The Gibbs energy of formation of solid NdFeO3 calculated by the least-squares regression analysis of the data obtained in the present study, and data for Fe0.95O and Nd2O3 from the literature, is given by ΔfG°m(NdFeO3, s)/kJ·mol-1(±2.0)=-1345.9+0.2542(T/K); (1000≤T/K ≤1650). The error in ΔfG°m(NdFeO3, s, T) includes the standard deviation in emf and the uncertainty in the data taken from the literature. Values of ΔfH°m(NdFeO3, s, 298.15 K) and S°m(NdFeO3, s, 298.15 K) calculated by the second law method are -1362.5 (±6) kJ·mol-1 and 123.9 (±2.5) J·K-1·mol-1, respectively. Based on the thermodynamic information, an oxygen potential diagram for the system Nd-Fe-O was developed at 1350 K.

The ESS neutrino facility for CP violation discovery

NASA Astrophysics Data System (ADS)

Baussan, Eric; Bouquerel, Elian; Dracos, Marcos

2017-09-01

The comparatively large value of the neutrino mixing angle θ 13 measured in 2012 by neutrino reactor experiments has opened the possibility to observe for the first time CP violation in the leptonic sector. The measured value of θ 13 also privileges the 2nd oscillation maximum for the discovery of CP violation instead of the usually used 1st oscillation maximum. The sensitivity at the 2nd oscillation maximum is about three times higher than at the 1st oscillation maximum implying a significantly lower sensitivity to systematic errors. Measuring at the 2nd oscillation maximum necessitates a very intense neutrino beam with the appropriate energy. The world’s most intense pulsed spallation neutron source, the European Spallation Source, has a proton linac with 5 MW power and 2 GeV energy. This linac also has the potential to become the proton driver of the world’s most intense neutrino beam with very high potential for the discovery of neutrino CP violation. The physics performance of that neutrino Super Beam in conjunction with a megaton Water Cherenkov neutrino detector installed ca 1000 m down in a mine at a distance of about 500 km from ESS has been evaluated. In addition, the use of such a detector will make it possible to extent the physics program to proton decay, atmospheric neutrinos and astrophysics searches. The ESS proton linac upgrade, the accumulator ring needed for proton pulse compression, the target station optimization and the physics potential are described. In addition to the production of neutrinos, this facility will also be a copious source of muons which could be used to feed a low energy nuSTORM facility, a future neutrino factory or a muon collider. The ESS linac, under construction, will reach full operation at 5 MW by 2023 after which the upgrades for the neutrino facility could start.

New laser surface treatments: cleaning, derusting, deoiling, depainting, deoxidizing, and degreasing

NASA Astrophysics Data System (ADS)

Daurelio, Giuseppe; Chita, Giuseppe; Cinquepalmi, Massimo

1997-08-01

Many materials as substrates and surface products have been tested. Typically ferrous (Carbon Steels and Stainless Steels) and non ferrous (Al and Cu metals and its alloys) ones have been employed. Some epoxy, polyurethane, polyester and acrylic paints in different thickness and color have been tested. Many types of the surface rust and oxide on different bulk material have been undertaken to test. Similarly some different types of oils and greases, usually used in industry against the oxidation, have been studied. Anyway many types of dirt, grit, calcareous one and so on, present on industrial components, have been laser cleaned without using solvents, acid baths and other ones. Different types of laser sources have been employed: an axial fast flow, 1.5 KW CO2 c.w. and pulsed laser source, emitting a 10.6 micrometers beam; a portable CO2 laser, c.w. (1 to 25 W) and pulsed (1 to 100 Hz and 400 ms max pulse duration) source, emitting a 10.6 micrometers beam with a multi-articulated seven mirrors guiding device and focussing head; a portable Nd-YAG laser, Q-switched and normal-mode source. 1st harmonic 1.06 micrometers (6 ns pulse duration), 2nd harmonic 532 nm (120 microsecond(s) duration pulse- 1J max per-pulse) wavelengths, multi-articulated seven mirrors beam guiding device, 20 Hz repetition rate. This lets shots with 600 mJ max energy per pulse and 100 MW peak power per-pulse with a very low beam divergence, 0.5 mrad at full angle; a transverse fast flow 2.5 kW CO2 laser.

Fabrication and characterization of carbon/oxygen-implanted waveguides in Nd3+-doped phosphate glasses

NASA Astrophysics Data System (ADS)

Liu, Chun-Xiao; Xu, Jun; Fu, Li-Li; Zheng, Rui-Lin; Zhou, Zhi-Guang; Li, Wei-Nan; Guo, Hai-Tao; Lin, She-Bao; Wei, Wei

2015-06-01

Optical planar waveguides in Nd3+-doped phosphate glasses are fabricated by a 6.0-MeV carbon ion implantation with a dose of 6.0×1014 ions/cm2 and a 6.0-MeV oxygen ion implantation at a fluence of 6.0×1014 ions/cm2, respectively. The guided modes and the corresponding effective refractive indices were measured by a modal 2010 prism coupler. The refractive index profiles of the waveguides were analyzed based on the stopping and range of ions in matter and the RCM reflectivity calculation method. The near-field light intensity distributions were measured and simulated by an end-face coupling method and a finite-difference beam propagation method, respectively. The comparison of optical properties between the carbon-implanted waveguide and the oxygen-implanted waveguide was carried out. The microluminescence and Raman spectroscopy investigations reveal that fluorescent properties of Nd3+ ions and glass microstructure are well preserved in the waveguide region, which suggests that the carbon/oxygen-implanted waveguide is a good candidate for integrated photonic devices.

A model for Cryogenian iron formation

NASA Astrophysics Data System (ADS)

Cox, Grant M.; Halverson, Galen P.; Poirier, André; Le Heron, Daniel; Strauss, Justin V.; Stevenson, Ross

2016-01-01

The Neoproterozoic Tatonduk (Alaska) and Holowilena (South Australia) iron formations share many characteristics including their broadly coeval (Sturtian) ages, intimate association with glaciogenic sediments, and mineralogy. We show that these shared characteristics extend to their neodymium (εNd) and iron isotope (δ56Fe) systematics. In both regions δ56Fe values display a distinct up-section trend to isotopically heavier values, while εNd values are primitive and similar to non-ferruginous mudstones within these successions. The δ56Fe profiles are consistent with oxidation of ferruginous waters during marine transgression, and the εNd values imply that much of this iron was sourced from the leaching of continental margin sediments largely derived from continental flood basalts. Rare earth element data indicate a secondary hydrothermal source for this iron.

Age and source of terrigenous rocks of the turan group of the bureya terrane of the eastern part of the central Asian foldbelt: Results of geochemical (Sm-Nd) and geochronological (U-Pb LA-ICP-MS) studies

NASA Astrophysics Data System (ADS)

Sorokin, A. A.; Smirnov, Yu. V.; Kotov, A. B.; Kovach, V. P.

2014-06-01

According to Sm-Nd isotopic-geochemical studies, the t Nd(DM) of the terrigenous rocks of the Turan Group of the Bureya terrane is 1.4-1.5 Ga and their sources are Precambrian rocks and (or) younger effusive rocks, the formation of which is related to the reworking of the Late Precambrian continental crust. The U-Pb LA-ICP-MS geochronological studies indicate dominant Vendian-Cambrian (588-483 Ma) and Late Riphean (865-737 Ma) detrital zircons. Our data point to their accumulation at the beginning of the Paleozoic rather than in the Precambrian as is accepted in modern stratigraphic schemes.

Hafnium isotope results from mid-ocean ridges and Kerguelen.

USGS Publications Warehouse

Patchett, P.J.

1983-01-01

176Hf/177Hf ratios are presented for oceanic volcanic rocks representing both extremes of the range of mantle Hf-Nd-Sr isotopic variation. Hf from critical mid-ocean ridge basalts shows that 176Hf/177Hf does indeed have a greater variability than 143Nd/144Nd and 87Sr/86Sr in the depleted mantle. This extra variation is essentially of a random nature, and can perhaps be understood in terms of known Rb/Sr-Sm/Nd-Lu/Hf fractionation relationships. At the other extreme of mantle isotopic compositions, 176Hf/177Hf ratios for igneous rocks from the Indian Ocean island of Kerguelen show a closely similar variation to published 143Nd/144Nd ratios for the same samples. Comparison of Hf-Nd-Sr isotopic relatonships for Tristan da Cunha, Kerguelen and Samoa reveals divergences in the mantle array for ocean-island magma sources, and perhaps suggests that these irregularities are largely the result of an extra component of 87Sr/86Sr variation.-G.R.

Hafnium isotope results from mid-ocean ridges and Kerguelen

USGS Publications Warehouse

Jonathan, Patchett P.

1983-01-01

176Hf/177Hf ratios are presented for oceanic volcanics representing both extremes of the range of mantle HfNdSr isotopic variation. Hf from critical mid-ocean ridgebasalts shows that 176Hf/177Hf does indeed have a greater variability than 143Nd/144Nd and 87Sr/86Sr in the depleted mantle. This extra variation is essentially of a random nature, and can perhaps be understood in terms of known Rb/SrSm/NdLu/Hf fractionation relationships. At the other extreme of mantle isotopic composition, 176Hf/177Hf ratios for igneous rocks from the Indian Ocean island of Kerguelen show a closely similar variation to published 143Nd/144Nd ratios for the same samples. Comparison of HfNdSr c relationships for Tristan da Cunha, Kerguelen and Samoa reveals divergences in the mantle array for ocean island magma sources, and perhaps suggests that these irregularities are largely the result of an extra component of 87Sr/86Sr variation. ?? 1983.

Synthesis and Thermodynamic Stability of Ba2B‧B″O6 and Ba3B*B″2O9 Perovskites Using the Molten Salt Method

NASA Astrophysics Data System (ADS)

Meng, Wei; Virkar, Anil V.

1999-12-01

A number of mixed perovskites of the types Ba2B‧B″O6 (BaB‧1/2B″1/2O3) and Ba3B*B″2O9 (BaB*1/3B″2/3O3) where B‧=Gd, La, Nd, Sm, or Y; B″=Nb and B*=Ca were synthesized by a conventional calcination process, as well as by the molten salt method. The former consists of calcining appropriate mixtures of oxide or carbonate precursors in air at elevated temperatures (∼1250°C). The latter method consists of adding appropriate mixtures of oxide or carbonate precursors to a molten salt bath at relatively low temperatures (on the order of 300 to 500°C) so that the requisite compound is formed by dissolution-reprecipitation. X-ray diffraction confirmed the formation of a single-phase perovskite in each case with calcination at 1250°C. In a molten salt bath, however, all except Ba2LaNbO6 and Ba2NdNbO6 formed the perovskite structure. On the contrary, powders of Ba2LaNbO6 and Ba2NdNbO6 formed by a high-temperature calcination process readily decomposed when introduced into the molten salt bath. The formation of the requisite perovskite at a temperature as low as 350°C in a molten salt suggests that: (a) The perovskite is stable at 350°C. (b) The molten salt exhibits sufficient precursor solubility for the dissolution-reprecipitation process to occur in a reasonable time. Similarly, the decomposition of Ba2LaNbO6 and Ba2NdNbO6 in a molten salt bath shows that these materials are thermodynamically unstable at the temperature of the molten salt bath.

Nature and origin of the sedimentary pile subducting in the Nankai Through

NASA Astrophysics Data System (ADS)

Chauvel, C.; Garcon, M.; Yobregat, E.; Chipoulet, C.; Labanieh, S.

2013-12-01

Nd-Hf isotopes and trace and major element concentrations were measured on bulk sediments recovered at Site C0012 during IODP Expedition 322 and 333 in the Shikoku basin. We analyzed the composition of different lithologies such as clay, claystone, sand, sandstone, and ash layers, all through the sedimentary pile, from the surface to the sediment-basalt interface, in order to identify compositional trends and source variations with depth. Major and trace element contents of the background sediments (hemipelagic mudstone) are very homogenous and span a relatively small range of values throughout the entire sedimentary pile. Their composition resembles that of the average upper continental crust of Rudnick and Gao (2003, Treatise on Geochemistry, Vol.3, p. 1-64). Nd and Hf isotopes are more variable, relatively unradiogenic (-8 < ɛNd < -3 ; -4 < ɛHf < +5) but display no systematic variations with depth (Fig. 1). Such isotopic compositions indicate that the background sedimentation of the Shikoku basin may consist of volcaniclastic material from the Izu-Bonin and/or Ryukyu arcs, detrital material eroded from SW Japan and relatively high amount of an evolved continental-derived component, probably Chinese loess as already suggested by Mahomet (2005, Sediment. Geol., 182, p.183-199). Compared to the background sedimentation, volcanic ash layers and volcaniclastic sandstones have very different trace element patterns and more radiogenic Nd-Hf isotopic signature (Fig. 1). Our results allow us to distinguish at least two different volcanic sources for these deposits. At the bottom of the sedimentary pile, siliciclastic sandstones with a mid-Miocene age are present; they have remarkably low ɛNd and ɛHf values (i.e. ɛNd < -8 and ɛHf < -5). Such isotopic compositions clearly demonstrate that their source cannot be the Japanese mainland, as suggested by previous studies (e.g. Underwood et al, 2009, Exp.322 PR ; Fergusson, 2003, Proc. ODP, Sci. Results 190/196). These sandstones are also too coarse to result from an accumulation of Chinese loess transported by wind (particles usually finer than 40 μm). Given the location of the Shikoku basin at 15Ma, we suggest that the siliciclastic sandstones mainly consists of detrital materials transported by Chinese rivers up to the sea in the Shikoku basin. Variations of ɛNd as a function of depth. Potential sediment sources are indicated by color bands

Carbon and Neodymium Isotopic Fingerprints of Atlantic Deep Ocean Circulation During the Warm Pliocene

NASA Astrophysics Data System (ADS)

Riesselman, C. R.; Scher, H.; Robinson, M. M.; Dowsett, H. J.; Bell, D. B.

2012-12-01

Earth's future climate may resemble the mid-Piacenzian Age of the Pliocene, a time when global temperatures were sustained within the range predicted for the coming century. Surface and deep water temperature reconstructions and coupled ocean-atmosphere general circulation model simulations by the USGS PRISM (Pliocene Research Interpretation and Synoptic Mapping) Group identify a dramatic North Atlantic warm surface temperature anomaly in the mid-Piacenzian (3.264 - 3.025 Ma), accompanied by increased evaporation. The anomaly is detected in deep waters at 46°S, suggesting enhanced meridional overturning circulation and more southerly penetration of North Atlantic Deep Water (NADW) during the PRISM interval. However deep water temperature proxies are not diagnostic of water mass and some coupled model simulations predict transient decreases in NADW production in the 21st century, presenting a contrasting picture of future climate. We present a new multi-proxy investigation of Atlantic deep ocean circulation during the warm mid-Piacenzian, using δ13C of benthic foraminifera as a proxy for water mass age and the neodymium isotopic composition of fossil fish teeth (ɛNd) as a proxy for water mass source and mixing. This reconstruction utilizes both new and previously published data from DSDP and ODP cores along equatorial (Ceara Rise), southern mid-latitude (Walvis Ridge), and south Atlantic (Meteor Rise/Agulhas Ridge) depth transects. Additional end-member sites in the regions of modern north Atlantic and Southern Ocean deep water formation provide a Pliocene baseline for comparison. δ13C throughout the Atlantic basin is remarkably homogenous during the PRISM interval. δ13C values of Cibicidoides spp. and C. wuellerstorfi largely range between 0‰ and 1‰ at North Atlantic, shallow equatorial, southern mid-latitude, and south Atlantic sites with water depths from 2000-4700 m; both depth and latitudinal gradients are generally small (~0.3‰). However, equatorial Ceara Rise sites below 3500 m diverge, with δ13C values as low as -1.2‰ at ~3.15 Ma. The uniquely negative δ13C values at deep Ceara rise sites suggest that, during PRISM warmth, the oldest Atlantic deep waters may have resided along the modern deep western boundary current, while younger deep water masses were concentrated to the south and east. In the modern Atlantic, the ɛNd value of southern-sourced waters is more radiogenic than that of northern-sourced waters, providing a complimentary means to characterize Pliocene water mass geometry. ɛNd values from shallow (2500 m) and deep (4700 m) Walvis Ridge sites average -10 and -11 respectively; the shallow site is somewhat more radiogenic than published coretop ɛNd (-12), suggesting enhanced Pliocene influence of southern-sourced water masses. Ongoing analytical efforts will fingerprint Piacenzian ɛNd from north and south deep water source regions and will target additional depth transect ɛNd, allowing us to investigate the possibility that "older" carbon isotopic signatures at western equatorial sites reflect entrainment of proto-NADW while "younger" signatures at southern and eastern sites reflect the influence of southern-sourced deep water.

Rare earth patterns in shergottite phosphates and residues

NASA Technical Reports Server (NTRS)

Laul, J. C.

1987-01-01

Leaching experiments with 1M HCl on ALHA 77005 powder show that rare earth elements (REE) are concentrated in accessory phosphate phases (whitlockite, apatite) that govern the REE patterns of bulk shergottites. The REE patterns of whitlockite are typically light REE-depleted with a negative Eu anomaly and show a hump at the heavy REE side, while the REE pattern of apatite (in Shergotty) is light REE-enriched. Parent magmas are calculated from the modal compositions of residues of ALHA 77005, Shergotty, and EETA 79001. The parent magmas lack a Eu anomaly, indicating that plagioclase was a late-stage crystallizing phase and that it probably crystallized before the phosphates. The parent magmas of ALHA 77005 and Shergotty have similar REE patterns, with a subchondritic Nd/Sm ratio. However, the Sm/Nd isotopoics require a light REE-depleted source for ALHA 77005 (if the crystallization age is less than 600 Myr) and a light REE-enriched source for Shergotty. Distant Nd and Sr isotopic signatures may suggest different source regions for shergottites.

Geochemical evidence for the provenance of aeolian deposits in the Qaidam Basin, Tibetan Plateau

NASA Astrophysics Data System (ADS)

Du, Shisong; Wu, Yongqiu; Tan, Lihua

2018-06-01

The main purpose of this study is to analyse the material source of different grain-size components of dune sand in the Qaidam Basin. We determined the trace and rare earth element (REE) compositions and Sr-Nd isotopic compositions of the coarse (75-500 μm) and fine (<75 μm) fractions of surface sediment samples. The comparison of the immobile trace element and REE compositions, Sr-Nd isotopic compositions and multidimensional scaling (MDS) results of the dune sands with those of different types of sediments in potential source areas revealed the following information. (1) The fine- and coarse-grained fractions of dune sands in the Qaidam Basin exhibit distinctly different elemental concentrations, elemental patterns and characteristic parameters of REE. Moreover, Sr-Nd isotopic differences also exist between different grain-size fractions of aeolian sand, which means that different grain-size fractions of these dune sands have different source areas. (2) The geochemical characteristics of the coarse particles of dune sand exhibit obvious regional heterogeneity and generally record a local origin derived from local fluvial sediments and alluvial/proluvial sediments. The coarse- and fine-grained dune sand in the southern Qaidam Basin mainly came from Kunlun Mountains, whereas the coarse- and fine-grained dune sand in the northeastern Qaidam Basin mainly came from Qilian Mountains. (3) The fine-grained fractions of sediments throughout the entire Qaidam Basin may have been affected by the input of foreign materials from the Tarim Basin.

High Precision 142Nd/144Nd and 143Nd/144Nd Isotope Ratio Measurements in Rock Samples

NASA Astrophysics Data System (ADS)

Ali, A.; Srinivasan, G.

2009-05-01

The long-lived 147Sm-143Nd system with a half-life (T1/2) of 106 Gyr is generally used for geochronology. The short-lived 146Sm-142Nd system (T1/2= 103 Myr) is used as a geological tracer to track early (˜500 Ma) silicate differentiation [1] events in different planetary bodies. The isotope composition measurements by thermal ionization mass spectrometry (TIMS) require purification of Nd using chemical separation methods. This is important as an impure sample will give both a very poor ion yield and cause beam instability in the mass spectrometer, potentially resulting in a poor analysis [2]. The separation of Nd for 143Nd isotope measurement is, fairly straightforward because there is no isobaric interference of any other REE. While 142Nd isotope analysis needs chemically separated Nd fraction to be ˜100% Ce-free as latter is composed of a substantial amount of 142Ce isotope. A 4-steps technique, modified from Caro et al., [3], for the separation of Nd is established at the Cosmochemistry Laboratory of University of Toronto, Canada and applied to the measurement of Nd isotope ratios in geological reference sample BCR-2 (USGS, Columbia River basalt) using TIMS. Results of the isotopic ratios obtained for BCR-2 are in good agreement with published values [e.g., 4]. Analytical work on the samples discovered as the oldest rocks on Earth [5] from Nuvvuagittuq greenstone belt in Québec, Canada and various meteorites is in progress. An account of the procedures involved is briefly described here. All working solutions and acids were prepared using >18.2 MΩ.cm-1 H2O from a Milli-Q water system. Experiments were performed under Class 100 clean work bench with acid-cleaned apparatus and plastic-ware. The whole rock powders were weighed (20-30 mg) and dissolved in a mixture of HF and HNO3 using PFA vials and heated at 110°C. Further decomposition was done in Teflon bomb in the oven at 205°C. Later on contents of the Teflon bomb were transferred to vials and fluorides were removed with a mixtures of HClO4 and HCl. Finally the digested samples were dissolved in 4N HCl prior to the column chromatography. The separation of alkalis and REE was achieved with 2 ml BioRad column using AG®50W-X12 resin; following which the separation of Nd and Sm fractions was achieved using Ln-Spec resin in PFA column. Results: Triple filament geometry was used to measure Nd as a metal in multi-dynamic mode using Isoprobe-T TIMS. About 600x10-9 g of JNdi-1 standard [6] produced a 142Nd beam strength of ~5×10-11 A; 400 cycles constituted one measurement, where each cycle consisted of 4 sequences of 10 second counting time. A set of ˜10 measurements of JNdi-1 gave extremely accurate and precise ratios for 142/144, 143/144 and 145/144 with internal precision better than 4 ppm and an external precision of less than 7 ppm in all cases. The BCR-2 samples were loaded ˜200 ng (factor of 4 less than JNdi-1) and therefore their operating signal strength for 142Nd was ˜1×10-11 A. Based on our analyses we conclude that the internal precision for BCR-2 samples in the range of 8-9 ppm and their external precision is comparable to JNdi-1. References: [1] Caro et al, (2008) Nature 452, 336-339; [2] Míková & Denková, (2007) Geosciences 52, 221-226; [3] Caro et al, (2003) Nature 432, 428-432; [4] Raczek et al., (2003) Geostandards Newsletter 27, No.2, 173-179; [5] O'Neil et al, (2008) Science 321, 1828-1831; [6] Tanaka et al., (2000) Chem Geol, 168, 279-281.

Electron doping effect on structural and magnetic phase transitions in Sr{sub 2-x}Nd{sub x}FeMoO{sub 6} double perovskites

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

Azad, A.K.; Eriksson, S.-G.; Khan, Abdullah

2006-05-15

Polycrystalline Sr{sub 2-x}Nd{sub x}FeMoO{sub 6} (x=0.0, 0.1, 0.2, 0.4) materials have been synthesized by a citrate co-precipitation method and studied by neutron powder diffraction (NPD) and magnetization measurements. Rietveld analysis of the temperature-dependent NPD data shows that the compounds (x=0.0, 0.1, 0.2) crystallize in the tetragonal symmetry in the range 10-400K and converts to cubic symmetry above 450K. The unit cell volume increases with increasing Nd{sup 3+} concentration, which is an electronic effect in order to change the valence state of the B-site cations. Antisite defects at the Fe-Mo sublattice increases with the Nd{sup 3+} doping. The Curie temperature wasmore » increased from 430K for x=0 to 443K for x=0.4. The magnetic moment of the Fe-site decreases while the Mo-site moment increases with electron doping. The antiferromagnetic arrangement causes the system to show a net ferrimagnetic moment.« less

Identifying the origins of local atmospheric deposition in the steel industry basin of Luxembourg using the chemical and isotopic composition of the lichen Xanthoria parietina.

PubMed

Hissler, Christophe; Stille, Peter; Krein, Andreas; Geagea, Majdi Lahd; Perrone, Thierry; Probst, Jean-Luc; Hoffmann, Lucien

2008-11-01

Trace metal atmospheric contamination was assessed in one of the oldest European industrial sites of steel production situated in the southern part of the Grand-Duchy of Luxembourg. Using elemental ratios as well as Pb, Sr, and Nd isotopic compositions as tracers, we found preliminary results concerning the trace metal enrichment and the chemical/isotopic signatures of the most important emission sources using the lichen Xanthoria parietina sampled at 15 sites along a SW-NE transect. The concentrations of these elements decreased with increasing distance from the historical and actual steel-work areas. The combination of the different tracers (major elements, Rare Earth Element ratios, Pb, Sr and Nd isotopes) enabled us to distinguish between three principal sources: the historical steel production (old tailings corresponding to blast-furnace residues), the present steel production (industrial sites with arc electric furnace units) and the regional background (baseline) components. Other anthropogenic sources including a waste incinerator and major roads had only weak impacts on lichen chemistry and isotopic ratios. The correlation between the Sr and Nd isotope ratios indicated that the Sr-Nd isotope systems represented useful tools to trace atmospheric emissions of factories using scrap metal for steel production.

The geochemistry of primitive volcanic rocks of the Ankaratra volcanic complex, and source enrichment processes in the genesis of the Cenozoic magmatism in Madagascar

NASA Astrophysics Data System (ADS)

Melluso, L.; Cucciniello, C.; le Roex, A. P.; Morra, V.

2016-07-01

The Ankaratra volcanic complex in central Madagascar consists of lava flows, domes, scoria cones, tuff rings and maars of Cenozoic age that are scattered over 3800 km2. The mafic rocks include olivine-leucite-nephelinites, basanites, alkali basalts and hawaiites, and tholeiitic basalts. Primitive samples have high Mg# (>60), high Cr and Ni concentrations; their mantle-normalized patterns peak at Nb and Ba, have troughs at K, and smoothly decrease towards the least incompatible elements. The Ankaratra mafic rocks show small variation in Sr-Nd-Pb isotopic compositions (e.g., 87Sr/86Sr = 0.70377-0.70446, 143Nd/144Nd = 0.51273-0.51280, 206Pb/204Pb = 18.25-18.87). These isotopic values differ markedly from those of Cenozoic mafic lavas of northern Madagascar and the Comoro archipelago, typical Indian Ocean MORB and oceanic basalt end-members. The patterns of olivine nephelinitic magmas can be obtained through 3-10% partial melting of a mantle source that was enriched by a Ca-rich alkaline melt, and that contained garnet, carbonates and phlogopite. The patterns of tholeiitic basalts can be obtained after 10-12% partial melting of a source enriched with lower amounts of the same alkaline melt, in the spinel- (and possibly amphibole-) facies mantle, hence in volumes where carbonate is not a factor. The significant isotopic change from the northernmost volcanic rocks of Madagascar and those in the central part of the island implicates a distinct source heterogeneity, and ultimately assess the role of the continental lithospheric mantle as source region. The source of at least some volcanic rocks of the still active Comoro archipelago may have suffered the same time-integrated geochemical and isotopic evolution as that of the northern Madagascar volcanic rocks.

A graphical method for identifying the six types of non-deep physiological dormancy in seeds.

PubMed

Soltani, E; Baskin, C C; Baskin, J M

2017-09-01

We present a new seed dormancy classification scheme for the non-deep level of the class physiological dormancy (PD), which contains six types. Non-deep PD is divided into two sublevels: one for seeds that exhibit a dormancy continuum (types 1, 2 and 3) and the other for those that do not exhibit a dormancy continuum (types 4, 5 and 6). Analysis of previous studies showed that different types of non-deep PD also can be identified using a graphical method. Seeds with a dormancy (D) ↔ conditional dormancy (CD) ↔ non-dormancy (ND) cycle have a low germination percentage in the early stages of CD, and during dormancy loss the germination capacity increases. However, seeds with a CD/ND (i.e. D→CD↔ND) cycle germinate to a high percentage at a narrow range of temperatures in the early stages of CD. Cardinal temperatures for seeds with either a D/ND or a CD/ND cycle change during dormancy loss: the ceiling temperature increases in seeds with Type 1, the base temperature decreases in seeds with Type 2 and the base and ceiling temperatures decrease and increase, respectively, in seeds with Type 3. Criteria for distinguishing the six types of non-deep PD and models of the temperature functions of seeds with types 1, 2 and 3 with both types of dormancy cycles are presented. The relevancy of our results to modelling the timing of weed seedling emergence is briefly discussed. © 2017 German Botanical Society and The Royal Botanical Society of the Netherlands.

Hemostatic properties of the free-electron laser

NASA Astrophysics Data System (ADS)

Cram, Gary P., Jr.; Copeland, Michael L.

1998-09-01

We have investigated the hemostatic properties of the free-electron laser (FEL) and compared these properties to the most commonly used commercial lasers in neurosurgery, CO 2 and Nd:YAG, using an acute canine model. Arterial and venous vessels, of varying diameters from 0.1 to 1.0 mm, were divided with all three lasers. Analysis of five wavelengths of the FEL (3.0, 4.5, 6.1, 6.45, and 7.7 microns) resulted in bleeding without evidence of significant coagulation, regardless of whether the vessel was an artery or vein. Hemorrhage from vessels less than 0.4 mm diameter was subsequently easily controlled with Gelfoam® (topical hemostatic agent) alone, whereas larger vessels required bipolar electrocautery. No significant charring, or contraction of the surrounding parenchyma was noted with any of the wavelengths chosen from FEL source. The CO 2 laser, in continuous mode, easily coagulated vessels with diameters of 4 mm and less, while larger vessels displayed significant bleeding requiring bipolar electrocautery for control. Tissue charring was noted with application of the CO 2 laser. In super pulse mode, the CO 2 laser exhibited similar properties, including significant charring of the surrounding parenchyma. The Nd:YAG coagulated all vessels tested up to 1.4 mm, which was the largest diameter cortical artery found, however this laser displayed significant and extensive contraction and retraction of the surrounding parenchyma. In conclusion, the FEL appears to be a poor hemostatic agent. Our results did not show any benefit of the FEL over current conventional means of achieving hemostasis. However, control of hemorrhage was easily achieved with currently used methods of hemostasis, namely Gelfoam® or bipolar electrocuatery. Although only cortical vessels in dogs were tested, we feel this data can be applied to all animals, including humans, and the peripheral, as well as central, vasculature, as our data on the CO 2 and Nd:YAG appear to closely support previous reports of hemostasis of these two lasers obtained in other models.

Generation of syntectonic calc-alkaline, magnesian granites through remelting of pre-tectonic igneous sources - U-Pb zircon ages and Sr, Nd and Pb isotope data from the Donkerhoek granite (southern Damara orogen, Namibia)

NASA Astrophysics Data System (ADS)

Schwark, L.; Jung, S.; Hauff, F.; Garbe-Schönberg, D.; Berndt, J.

2018-06-01

The 541 ± 4 Ma-old magnesian, weakly peraluminous, calc-alkalic Donkerhoek Onanis granite is part of the ca. 6000 km2 large Donkerhoek batholith in the Southern Zone of the Damara orogen of Namibia. Linear major and trace element variations and decreasing MgO, FeO, Al2O3, CaO, K2O, Na2O, Ba and Sr concentrations with increasing SiO2 indicate that this part of the batholith represent a coherent mass and underwent fractional crystallization processes. The Donkerhoek Onanis granites are isotopically evolved (initial εNd: -4.7 to -12.3, initial 87Sr/86Sr: 0.7099-0.7157) with moderately radiogenic Pb isotope ratios (206Pb/204Pb: 17.26-18.22; 207Pb/204Pb: 15.59-15.67; 208Pb/204Pb: 37.60-38.06). Beside heterogeneities imparted by the sources, an evaluation of LREE fractionation and Nd isotope data suggests that AFC processes also modified some samples. Based on the chemical and isotope data, the Donkerhoek Onanis granites cannot be derived by partial melting of Al- and Fe-rich metasedimentary rocks of the Kuiseb formation in which they intruded. Instead, melting of meta-igneous crustal sources with Proterozoic crustal residence ages is more likely. Three igneous to meta-igneous rock suites from the area (Matchless amphibolites, Proterozoic mafic to felsic gneisses from the southern Kalahari craton basement, syn-tectonic Salem granodiorites to granites) are potential sources. An evaluation of chemical and isotope data suggests that remelting of early syn-orogenic Salem-type granites is the most likely process which would also explain the existence of ca. 563 ± 4 Ma-old zircon in the Donkerhoek Onanis granites. Comparison of the Donkerhoek Onanis granites with experimentally derived melt compositions from an intermediate igneous parent indicates temperatures between 800 and 850 °C. It is suggested that the Pan-African igneous activity in this part of the Damara Belt was a moderate-temperature intra-crustal event. Although there are some compositional similarities with juvenile granites generated in subduction zones, unradiogenic Pb isotope ratios and moderately radiogenic Sr and unradiogenic Nd isotopes suggest that reprocessed crustal rocks are more likely sources. Previously obtained high δ18O values of the Donkerhoek Onanis granites ranging from 11.8 to 13.6‰, covering the range of δ18O values obtained on Salem-type granites from the area (12.5-13.3‰) confirm this view. In contrast to igneous processes along active continental margins that produce juvenile batholiths with calc-alkaline affinities, this igneous event was not a major crust-forming episode and the Donkerhoek Onanis granites represent reprocessed crustal material.

Occurrence of phthalic acid esters in source waters: a nationwide survey in China during the period of 2009-2012.

PubMed

Liu, Xiaowei; Shi, Jianghong; Bo, Ting; Zhang, Hui; Wu, Wei; Chen, Qingcai; Zhan, Xinmin

2014-01-01

The first nationwide survey of six phthalic acid esters (PAEs) (diethyl phthalate (DEP); dimethyl phthalate (DMP); di-n-butyl phthalate (DBP); butyl benzyl phthalate (BBP); bis(2-ethylhexyl) phthalate (DEHP); di-n-octyl phthalate (DnOP)) in source waters was conducted in China. The results showed these PAEs were ubiquitous in source waters. DBP and DEHP were the most frequently detected with high concentrations ranging nd-1.52 μg/L and nd-6.35 μg/L, respectively. These PAEs concentrations (except DBP) in surface water (rivers, lakes and reservoirs) were generally higher than those in groundwater; DBP had high concentrations in groundwater in Northeast China (Liao River Basin) and North China (Hai River Basin). Their concentrations in the northern regions were generally higher than those in the southern and eastern regions; particularly, in North China. Three short-chain PAEs (DMP, DEP and DBP) were detected with high concentrations in Hai River Basin, Pearl River Basin and Yellow River Basin. Copyright © 2013 Elsevier Ltd. All rights reserved.

Impact of event positioning algorithm on performance of a whole-body PET scanner using one-to-one coupled detectors

NASA Astrophysics Data System (ADS)

Surti, S.; Karp, J. S.

2018-03-01

The advent of silicon photomultipliers (SiPMs) has introduced the possibility of increased detector performance in commercial whole-body PET scanners. The primary advantage of these photodetectors is the ability to couple a single SiPM channel directly to a single pixel of PET scintillator that is typically 4 mm wide (one-to-one coupled detector design). We performed simulation studies to evaluate the impact of three different event positioning algorithms in such detectors: (i) a weighted energy centroid positioning (Anger logic), (ii) identifying the crystal with maximum energy deposition (1st max crystal), and (iii) identifying the crystal with the second highest energy deposition (2nd max crystal). Detector simulations performed with LSO crystals indicate reduced positioning errors when using the 2nd max crystal positioning algorithm. These studies are performed over a range of crystal cross-sections varying from 1  ×  1 mm2 to 4  ×  4 mm2 as well as crystal thickness of 1 cm to 3 cm. System simulations were performed for a whole-body PET scanner (85 cm ring diameter) with a long axial FOV (70 cm long) and show an improvement in reconstructed spatial resolution for a point source when using the 2nd max crystal positioning algorithm. Finally, we observe a 30-40% gain in contrast recovery coefficient values for 1 and 0.5 cm diameter spheres when using the 2nd max crystal positioning algorithm compared to the 1st max crystal positioning algorithm. These results show that there is an advantage to implementing the 2nd max crystal positioning algorithm in a new generation of PET scanners using one-to-one coupled detector design with lutetium based crystals, including LSO, LYSO or scintillators that have similar density and effective atomic number as LSO.

Tracing crustal contamination along the Java segment of the Sunda Arc, Indonesia

NASA Astrophysics Data System (ADS)

Jolis, E. M.; Troll, V.; Deegan, F.; Blythe, L.; Harris, C.; Freda, C.; Hilton, D.; Chadwick, J.; Van Helden, M.

2012-04-01

Arc magmas typically display chemical and petrographic characteristics indicative of crustal input. Crustal contamination can take place either in the mantle source region or as magma traverses the upper crust (e.g. [1]). While source contamination is generally considered the dominant process (e.g. [2]), late-stage crustal contamination has been recognised at volcanic arcs too (e.g. [3]). In light of this, we aim to test the extent of upper crustal versus source contamination along the Java segment of the Sunda arc, which, due its variable upper crustal structure, is an exemplary natural laboratory. We present a detailed geochemical study of 7 volcanoes along a traverse from Anak-Krakatau in the Sunda strait through Java and Bali, to characterise the impact of the overlying crust on arc magma composition. Using rock and mineral elemental geochemistry, radiogenic (Sr, Nd and Pb) and, stable (O) isotopes, we show a correlation between upper crustal composition and the degree of upper crustal contamination. We find an increase in 87Sr/86Sr and δ18O values, and a decrease in 143Nd/144Nd values from Krakatau towards Merapi, indicating substantial crustal input from the thick continental basement present. Volcanoes to the east of Merapi and the Progo-Muria fault transition zone, where the upper crust is thinner, in turn, show considerably less crustal input in their isotopic signatures, indicating a stronger influence of the mantle source. Our new data represent a systematic and high-resolution arc-wide sampling effort that allows us to distinguish the effects of the upper crust on the compositional spectrum of individual volcanic systems along the Sunda arc. [1] Davidson, J.P, Hora, J.M, Garrison, J.M & Dungan, M.A 2005. Crustal Forensics in Arc Magmas. J. Geotherm. Res. 140, 157-170; [2] Debaille, V., Doucelance, R., Weis, D., & Schiano, P. 2005. Geochim. Cosmochim. Acta, 70,723-741; [3] Gasparon, M., Hilton, D.R., & Varne, R. 1994. Earth Planet. Sci. Lett., 126, 15-22.

Back-arc basalts from the Loncopue graben (Province of Neuquen, Argentina)

NASA Astrophysics Data System (ADS)

Varekamp, J. C.; Hesse, A.; Mandeville, C. W.

2010-11-01

Young basaltic back-arc volcanoes occur east of the main Andes chain at about 37.5°-39°S in the Loncopue graben, Province of Neuquen, Argentina. These olivine-rich basalts and trachybasalts have up to 8% MgO, with high Ni and Cr contents, but highly variable incompatible element concentrations. Mafic lava flows and cinder cones at the southern end of the graben lack phenocrystic plagioclase. The northern samples have relative Ta-Nb depletions and K, Pb and LREE enrichment. These samples strongly resemble rocks of the nearby arc volcanoes Copahue and Caviahue, including their Fe-Ti enrichment relative to the main Andes arc rocks. The Sr, Nd and Pb isotope ratios show that the source regions of these back-arc basalts are enriched in subducted components that were depleted in the aqueous mobile elements such as Cs, Sr and Ba as a result of prior extractions from the subducted complex below the main arc. Some mafic flows show slightly low 206Pb/ 204Pb and 143Nd/ 144Nd values as well as incompatible trace element ratios similar to southern Patagonia plateau back-arc basalts, suggesting contributions from an EM1 mantle source. Geothermometry and barometry suggest that the basalts crystallized and fractionated small amounts of olivine and spinel at ˜ 35 km depth at temperatures of 1170-1220 °C, at about QFM + 0.5 to QFM + 1 with 1-2% H 2O, and then rose rapidly to the surface. The Loncopue graben back-arc basalts are transitional in composition between the South Patagonia back-arc plateau basalts and the Caviahue and Copahue arc volcanoes to the northwest. The EM1 source endmember is possibly the subcontinental lithospheric mantle. Strong variations in incompatible element enrichment and isotopic compositions between closely spaced cinder cones and lava flows suggest a heterogeneous mantle source for the Loncopue graben volcanics.

Pb-Sr-Nd isotopes in surficial materials at the Pebble Porphyry Cu-Au-Mo Deposit, Southwestern Alaska: can the mineralizing fingerprint be detected through cover?

USGS Publications Warehouse

Ayuso, Robert A.; Kelley, Karen D.; Eppinger, Robert G.; Forni, Francesca

2013-01-01

The Cretaceous Pebble porphyry Cu-Au-Mo deposit is covered by tundra and glacigenic sediments. Pb-Sr-Nd measurements were done on sediments and soils to establish baseline conditions prior to the onset of mining operations and contribute to the development of exploration methods for concealed base metal deposits of this type. Pebble rocks have a moderate range for 206Pb/204Pb = 18.574 to 18.874, 207Pb/204Pb = 15.484 to 15.526, and 208,Pb/204Pb = 38.053 to 38.266. Mineralized granodiorite shows a modest spread in 87Sr/86Sr (0.704354–0.707621) and 143Nd/144Nd (0.512639–0.512750). Age-corrected (89 Ma) values for the granodiorite yield relatively unradiogenic Pb (e.g., 207Pb/204Pb 87Sr/86Sr, and positive values of ɛNd (1.00–4.52) that attest to a major contribution of mantle-derived source rocks. Pond sediments and soils have similar Pb isotope signatures and 87Sr/86Sr and 143Nd/144Nd values that resemble the mineralized granodiorites. Glacial events have obscured the recognition of isotope signatures of mineralized rocks in the sediments and soils. Baseline radiogenic isotope compositions, prior to the onset of mining operations, reflect natural erosion, transport and deposition of heterogeneous till sheets that included debris from barren rocks, mineralized granodiorite and sulfides from the Pebble deposit, and other country rocks that pre- and postdate the mineralization events. Isotopic variations suggest that natural weathering of the deposit is generally reflected in these surficial materials. The isotope data provide geochemical constraints to glimpse through the extensive cover and together with other geochemical observations provide a vector to concealed mineralized rocks genetically linked with the Pebble deposit.

Discovery of Extremely Embedded X-ray Sources in the R Coronae Australis Star Forming Core

NASA Technical Reports Server (NTRS)

Hamaguchi, Ken-Ji; Corcoran, Michael F.; Petre, Rob; White, Nicholas E.; Stelzer, Beate; Nedachi, Ko; Kobayashi, Naoto

2004-01-01

We detected three extremely embedded X-ray sources in the R Corona Australis (R CrA) star forming core, IRS 7 region. Two weak X-ray sources are associated with the VLA centimeter radio sources 10E & W, whereas the third brightest source detected in the two XMM-Newton observations on March 2003 has no counterpart at any wavelengths. The large K-band upper-limit (19.4m) measured with the University of Hawaii 88-inch Telescope and strong absorption derived in X-rays (N(sub H) approx. 2.8 x 10(exp 23)/sq cm equivalent to A(sub v) approx. 180 m) indicate that the source is younger than typical Class I protostars, i.e. a Class 0 protostar or an intermittent phase between Class 0 and Class I protostars. The X-ray luminosity was less than one thirtieth (log L(sub x) less than or approx. equals 29.3 ergs/s) in the former Chandra observation in October 2000, which suggests that the X-ray activity, probably generated by magnetic activity, is triggered by an intermittent mass accretion episode such as FU Ori type outbursts. Because the source was detected at high significance in the XMM-Newton observations (approx. 2,000 cnts), X-ray properties of such young protostars can be well investigated for the first time. The light curves were constant in the 1st observation and increased linearly by a factor of two during 30 ksec in the 2nd observation. Both spectra showed iron K lines originated in hot thin-thermal plasma and fluorescence by cold gas. They can be reproduced by an absorbed thin-thermal plasma model with a Gaussian component at 6.4 keV (kT approx. 3-4 keV, L(sub x) approx. 7-20 x 10(exp 30) ergs/s). The rising timescale of the light curves in the 2nd observation was too slow for magnetically generated X-ray flares, whereas large equivalent width of the fluorescence iron K line in the 1st observation (approx. 810 eV) requires strong partial covering of the X-ray source. These results suggest that a confined hot (perhaps accretion) spot on the protostellar core was behind the star in the 1st observation and just appeared in the 2nd observation due to the core rotation with period of greater than or approx. 22.8 days, which is much slower than the break-up velocity previously assumed for young protostars. This means that the source had quiescent X-ray activity during the observations with an order of magnitude stronger level than Class I (older) protostars. We also consider whether the X-ray source associated with 10E could be shock heated plasma by a collision of a jet emanating from the tentative Class 0 object.

Late Cambrian - Early Ordovician turbidites of Gorny Altai (Russia): Compositions, sources, deposition settings, and tectonic implications

NASA Astrophysics Data System (ADS)

Kruk, Nikolai N.; Kuibida, Yana V.; Shokalsky, Sergey P.; Kiselev, Vladimir I.; Gusev, Nikolay I.

2018-06-01

The Cambrian-Ordovician transition was the time of several key events in the history of Central Asia. They were the accretion of Mariana-type island arc systems to the Siberian continent, the related large-scale orogeny and intrusions of basaltic and granitic magma and the formation of a huge turbidite basin commensurate with the Bengal Gulf basin in the western part of the Central Asian orogenic belt (CAOB). The structure of the basin, as well as the sources and environments of deposition remain open to discussion. This paper presents new major- and trace-element data on Late-Cambrian-Early Ordovician turbidites from different parts of the Russian Altai and a synthesis of Nd isotope composition and ages of detrital zircons. The turbidites share chemical similarity with material shed from weathered continental arcs. Broad variations of CIA (39-73) and ICV (0.63-1.66) signatures in sandstones suggest origin from diverse sources and absence of significant sorting. Trace elements vary considerably and have generally similar patterns in rocks from different terranes. On the other hand, there are at least two provinces according to Nd isotope composition and age of detrital zircons. Samples from eastern Russian Altai contain only Phanerozoic zircons and have Nd isotope ratios similar to those in Early Cambrian island arcs (εNdt + 4.4… + 5.4; TNd(DM)-2-st = 0.8-0.9 Ga). Samples from central, western, and southern parts of Russian Altai contain Precambrian zircons (some as old as Late Archean) and have a less radiogenic Nd composition (εNdt up to -3.6; TNd(DM)-2-st up to 1.5 Ga). The chemical signatures of Late Cambrian to Early Ordovician turbidites indicate a provenance chemically more mature than the island arc rocks, and the presence of zircons with 510-490 Ma ages disproves their genetic relation with island arcs. The turbidite basin formed simultaneously with peaks of granitic and alkali-basaltic magmatism in the western Central Asian orogen and resulted from interplay of plate tectonic and plume tectonic processes.

Nanocrystalline NiNd{sub 0.01}Fe{sub 1.99}O{sub 4} as a gas sensor

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

Shinde, Tukaram J., E-mail: pshindetj@yahoo.co.in; Gadkari, Ashok B.; Jadhav, Sarjerao R.

2015-06-24

Nanocrystalline NiNd{sub 0.01}Fe{sub 1.99}O{sub 4} has been synthesized by oxalate co-precipitation method and was characterized by X-ray diffraction technique. X-ray diffraction analysis confirms the formation of single phase cubic spinel structure. Crystallite size of the ferrite lies in the nano-particle range. The gas sensing properties of nanocrystalline ferrite were studied for gases like Cl{sub 2}, LPG and C{sub 2}H{sub 5}OH. It was observed that NiNd{sub 0.01}Fe{sub 1.99}O{sub 4} is more sensitive towards chlorine followed by LPG at an operating temperature 277 °C compared to ethanol.

Momentum density and Fermi surface of Nd2-xCexCuO4-δ

NASA Astrophysics Data System (ADS)

Shukla, A.; Barbiellini, B.; Hoffmann, L.; Manuel, A. A.; Sadowski, W.; Walker, E.; Peter, M.

1996-02-01

High-temperature positron two-dimensional angular correlation of annihilation radiation (2D-ACAR) measurements have recently been succesfully applied to map parts of the Fermi surface of YBa2Cu3O7-δ. Using the same principle, we have been able to observe with a bulk sensitive method, the Fermi surface of Nd2-xCexCuO4-δ. Although positron trapping by defects and correlation effects are strong, positron 2D-ACAR measurements provide a signal from the Fermi surface which agrees with band-structure calculations, confirming earlier surface sensitive photoemission experiments.

Zircon U-Pb geochronology, Sr-Nd-Hf isotopic composition and geological significance of the Late Triassic Baijiazhuang and Lvjing granitic plutons in West Qinling Orogen

NASA Astrophysics Data System (ADS)

Duan, Meng; Niu, Yaoling; Kong, Juanjuan; Sun, Pu; Hu, Yan; Zhang, Yu; Chen, Shuo; Li, Jiyong

2016-09-01

The Qinling Orogen was a consequence of continental collision of the South China Craton with the North China Craton in the Triassic and caused widespread granitoid magmatism. However, the petrogenesis of these granitoids remains controversial. In this paper, we choose the Baijiazhuang (BJZ) and Lvjing (LJ) plutons in the West Qinling Orogen for a combined study of the zircon U-Pb geochronology, whole-rock major and trace element compositions and Sr-Nd-Hf isotopic characteristics. We obtained zircon crystallization ages of 216 Ma and 212 Ma for the BJZ and the LJ plutons, respectively. The granitoid samples from both plutons have high K2O metaluminous to peraluminous compositions. They are enriched in large ion lithophile elements (LILEs), light rare earth elements (LREEs) and depleted in high field-strength elements (HFSEs) with significant negative Eu anomalies. The BJZ samples have initial Sr isotopic ratios of 0.7032 to 0.7078, εNd(t) of - 10.99 to - 8.54 and εHf (t) of - 10.22 to - 6.41. The LJ granitoids have initial Sr isotopic ratios of 0.7070 to 0.7080, εNd(t) of - 5.37 to - 4.58 and εHf(t) of - 3.64 to - 1.78. The enriched isotopic characteristics of the two plutons are consistent with their source being dominated by ancient continental crust. However, two BJZ samples show depleted Sr isotope compositions, which may infer possible involvement of mantle materials. Mantle-derived melt, which formed from partial melting of mantle wedge peridotite facilitated by dehydration of the subducted/subducting Mianlue ocean crust, provide the required heat for the crustal melting while also contributing to the compositions of these granitoids. That is, the two granitic plutons are magmatic responses to the closure of the Mianlue ocean basin and the continental collision between the Yangtze and South Qinling crustal terranes. (143Nd/144Nd)i = (143Nd/144Nd) - (147Sm/144Nd) × (eλt - 1), εNd(t) = [(143Nd/144Nd) / (143Nd/144Nd)CHUR(t) - 1] × 104, (143Nd/144Nd)CHUR(t) = 0.512638-0.1967 × (eλt - 1), TDM = 1/λ × ln{1 + [((143Nd/144Nd) - 0.51315) / ((147Sm/144Nd) - 0.21317)]}, λ Sm-Nd = 6.54 × 10- 12a- 1. (176Hf/177Hf)i = [(176Hf/177Hf) - (176Lu/177Hf) × (eλt - 1), εHf(t) = [(176Hf/177Hf) / (176Hf/177Hf)CHUR(t) - 1] × 104, TDM1 = 1/λ × ln[1 + ((176Hf/177Hf)Sample - (176Hf/177Hf)DM)/((176Lu/177Hf)Sample - (176Lu/177Hf)DM)], TDM2 = TDM1 - (TDM1 - t)((fCC - fSample) / (fCC - fDM)), fLu-Hf = (176Lu/177Hf)Sample / (176Lu/177Hf)CHUR-1, (176Lu/177Hf)CHUR = 0.0332, (176Hf/177Hf)CHUR, 0 = 0.282785, (176Lu/177Hf)DM = 0.0384, (176Hf/177Hf)DM = 0.28325, fCC, fSample, fDM are their own fLu-Hf, λ = 1.867 × 10- 11a- 1.

Deglacial Dust Provenance Changes in the Eastern Equatorial Pacific and Implications for ITCZ Movement

NASA Astrophysics Data System (ADS)

Xie, R.; Marcantonio, F.

2009-12-01

The provenance of the eolian dust component of deep-sea sediments has the potential to offer insights into changes in past atmospheric circulation patterns. Measuring temporal changes in dust provenance can shed more light on changes in the position of the Intertropical Convergence Zone (ITCZ), a region in which dust is removed from the upper troposphere by deep convection and scavenged by precipitation. The ITCZ should, therefore, act as a barrier separating wind-blown northern versus southern sources. Perhaps the best way to trace for provenance of dust sources is through the measurement of radiogenic isotope ratios. Here, we have analyzed Nd, Sr, and Pb isotope ratios in the detrital components extracted from deep-sea sediments in the eastern equatorial Pacific (EEP) along a meridional transect at 110W from 3S to 7N (ODP Leg 138, Sites 848 - 853). At each site, the sediments ranged in age from 0 to 25 ka. Detrital component extraction involved the chemical removal of the biogenic and authigenic sedimentary fractions. Preliminary detrital Nd isotope ratios show a range of 2.4 ɛNd units (from -5.7 to -3.3). There are distinct latitudinal trends in the ɛNd values, with more radiogenic values further south and less radiogenic values further north. This distinction holds true for both Holocene and glacial time. The difference in Nd isotope ratios at any one site between Holocene and glacial is smaller for the sites furthest North. The greatest Holocene-glacial differences in ɛNd occur at sites south of 3N, suggesting a distinct detrital component boundary at this latitude. The sites furthest north (7N and 5.29N) show the greatest variability in detrital 87Sr/86Sr isotope ratios, while sites furthest south (equator and 1.5N) show negligible variability. The detrital component of sediment at Site 851 (2.77N) has a Sr isotope variability that is intermediate between the northern and southern values, again suggesting a detrital boundary of some sort. We interpreted these preliminary results to suggest that the ITCZ position was displaced toward the south, with a paleo-position located between Site 851 (2.77N) and Site 852 (5.29N), from its average current location, which is approximately 7N. This supports one hypothesis put forward by McGee et al. [1], based on changes in dust flux for the same transect, that the ITCZ was displaced toward the south during the last glacial period. [1] McGee et al., 2007, EPSL 257, 215-230 .

Evaluation of the performance of small diode pumped UV solid state (DPSS) Nd:YAG lasers as new radiation sources for atmospheric pressure laser ionization mass spectrometry (APLI-MS).

PubMed

Kersten, Hendrik; Lorenz, Matthias; Brockmann, Klaus J; Benter, Thorsten

2011-06-01

The performance of a KrF* bench top excimer laser and a compact diode pumped UV solid state (DPSS) Nd:YAG laser as photo-ionizing source in LC-APLI MS is compared. The commonly applied bench-top excimer laser, operating at 248 nm, provides power densities of the order of low MW/cm(2) on an illuminated area of 0.5 cm(2) (8 mJ/pulse, 5 ns pulse duration, beam waist area 0.5 cm(2), 3 MW/cm(2)). The DPSS laser, operating at 266 nm, provides higher power densities, however, on a two orders of magnitude smaller illuminated area (60 μJ/pulse, 1 ns pulse duration, beam waist area 2 × 10(-3) cm(2), 30 MW/cm(2)). In a common LC-APLI MS setup with direct infusion of a 10 nM pyrene solution, the DPSS laser yields a significantly smaller ion signal (0.9%) and signal to noise ratio (1.4%) compared with the excimer laser. With respect to the determined low detection limits (LODs) for PAHs of 0.1 fmol using an excimer laser, LODs in DPSS laser LC-APLI MS in the low pmol regime are expected. The advantages of the DPSS laser with respect to applicability (size, cost, simplicity) may render this light source the preferred one for APLI applications not focusing on ultimately high sensitivities. Furthermore, the impact of adjustable ion source parameters on the performance of both laser systems is discussed in terms of the spatial sensitivity distribution described by the distribution of ion acceptance (DIA) measurements. Perspectives concerning the impact on future APLI-MS applications are given.

Effect of Soil Moisture on Chlorine Deposition (POSTPRINT)

DTIC Science & Technology

2014-01-01

obtained nd prepared for extraction (10 mL deionized water, 18 M/cm) nd subsequent analysis by ion chromatography [16] to measure l− concentrations. Ion ...Photobiol. A: Chem. 86 (1995) 1–7. 16] Determination of Inorganic Anions by Ion Chromatography , EPA Method 9056A, 2007, http://www.epa.gov/wastes/hazard...examine Cl2 eposition into soils with moisture contents from 0 to 0.2 (w/w) and ith varying organic matter contents. We use the chloride ion (Cl−) s

A Sr-Nd isotopic study of sand-sized sediment provenance and transport for the San Francisco Bay coastal system

USGS Publications Warehouse

Rosenbauer, Robert J.; Foxgrover, Amy C.; Hein, James R.; Swarzenski, Peter W.; Barnard, P.L.; Jaffee, B.E.; Schoellhamer, D.H.

2013-01-01

A diverse suite of geochemical tracers, including 87Sr/86Sr and 143Nd/144Nd isotope ratios, the rare earth elements (REEs), and select trace elements were used to determine sand-sized sediment provenance and transport pathways within the San Francisco Bay coastal system. This study complements a large interdisciplinary effort (Barnard et al., 2012) that seeks to better understand recent geomorphic change in a highly urbanized and dynamic estuarine-coastal setting. Sand-sized sediment provenance in this geologically complex system is important to estuarine resource managers and was assessed by examining the geographic distribution of this suite of geochemical tracers from the primary sources (fluvial and rock) throughout the bay, adjacent coast, and beaches. Due to their intrinsic geochemical nature, 143Nd/144Nd isotopic ratios provide the most resolved picture of where sediment in this system is likely sourced and how it moves through this estuarine system into the Pacific Ocean. For example, Nd isotopes confirm that the predominant source of sand-sized sediment to Suisun Bay, San Pablo Bay, and Central Bay is the Sierra Nevada Batholith via the Sacramento River, with lesser contributions from the Napa and San Joaquin Rivers. Isotopic ratios also reveal hot-spots of local sediment accumulation, such as the basalt and chert deposits around the Golden Gate Bridge and the high magnetite deposits of Ocean Beach. Sand-sized sediment that exits San Francisco Bay accumulates on the ebb-tidal delta and is in part conveyed southward by long-shore currents. Broadly, the geochemical tracers reveal a complex story of multiple sediment sources, dynamic intra-bay sediment mixing and reworking, and eventual dilution and transport by energetic marine processes. Combined geochemical results provide information on sediment movement into and through San Francisco Bay and further our understanding of how sustained anthropogenic activities which limit sediment inputs to the system (e.g., dike and dam construction) as well as those which directly remove sediments from within the Bay, such as aggregate mining and dredging, can have long-lasting effects

Evolution of Tethyan phosphogenesis along the northern edges of the Arabian--African shield during the Cretaceous--Eocene as deduced from temporal variations of Ca and Nd isotopes and rates of P accumulation

NASA Astrophysics Data System (ADS)

Soudry, D.; Glenn, C. R.; Nathan, Y.; Segal, I.; VonderHaar, D.

2006-09-01

The evolution of Tethyan phosphogenesis during the Cretaceous-Eocene is examined to try to explain fluctuations of phosphogenesis through time, and whether or not they reflect long-term changes in ocean circulation or in continental weathering. Twenty-seven time-stratigraphic phosphate levels in various Tethyan sites, covering a time span of about 90 Myr from the Hauterivian to the Eocene, were analyzed for 44Ca/ 42Ca and 143Nd/ 144Nd in their carbonate fluorapatite (CFA) fraction. P and Ca accumulation rates and bulk sedimentation rates were quantified throughout the Cretaceous-Eocene Negev sequence to examine how changes in 44Ca/ 42Ca and 143Nd/ 144Nd are reflected in the intensity of phosphogenesis. A clear-cut change occurs in ɛNd( T) and δ44Ca and in the rates of P and Ca accumulation and bulk sedimentation through the time analyzed. ɛNd( T) is much lower in the Hauterivian-Lower Cenomanian (- 12.8 to - 10.9) than in the Upper Cenomanian-Eocene (- 7.8 to - 5.9). Much lower δ44Ca values occur in the Hauterivian-Turonian (- 0.22 to + 0.02) than in the Coniacian-Eocene (+ 0.23 to + 0.40). P accumulation rates in the Negev steeply increase from < 200 μmol cm - 2 k yr - 1 in the Albian-Coniacian to ˜ 1500 μmol cm - 2 k yr - 1 in the Campanian, whereas a strong decrease is concomitantly recorded in the rates of Ca accumulation and bulk sedimentation. In addition, distinct ɛNd( T) values are shown by the phosphorites of the Negev (- 6.7 to - 6.4) and Egypt (- 9.1 to - 7.6) during the Campanian, and by those of the Negev (- 7.8 to - 6.3) and North Africa (- 10.1 to - 8.9) during the Maastrichtian-Eocene. The culmination of P accumulation rates in the Negev during the Campanian, occurring with a high in ɛNd( T) and δ44Ca and a low in sedimentation rates, indicates that paleoceanographic and paleogeographical factors mostly governed phosphorite accumulation in this area. The abrupt ɛNd( T) rise after the Cenomanian is attributed to increased incursion of Pacific (radiogenic) water masses into the Tethys, driven by the Late Cretaceous global sea-level rise, the connection between North and South Atlantic, the global post-Santonian cooling, and the progressive widening of the Caribbean threshold, all acting in combination to significantly intensify the Tethyan circumglobal current (TCC). It also reflects a weakening of the continental Nd signal due to a reduction of exposed landmasses caused by increased flooding of continental shelves. High δ44Ca values at those times also point to a decrease in weathering Ca +2 fluxes and expansion of carbonate sedimentation in shelves, both enriching seawater with isotopically heavy Ca +2. Deep ocean circulation intensified by the post-Santonian cooling of high latitudes increased P inventory in the Tethys basin, whereas the strengthened TCC and the folded shelf likely resulted in coastal and topographically-induced upwelling, supplying P-rich intermediate waters to southeastern Tethys shelves. Only in the Paleocene-Eocene, following major changes in global circulation produced by narrowing of Tethys and widening of the Atlantic, did phosphogenesis shifts its locus of high intensity to the western (Atlantic) Tethys and West African Atlantic coasts. This change in paleocirculation is expressed by distinctly differing ɛNd( T) in the Middle East and the North and West African phosphorites, suggesting different oceanic P sources and current systems for these two major groups of phosphorites. Our Nd isotope results further suggest a weaker TCC during the Mid-Cretaceous, becoming more intense in Late Cretaceous times. They also point to the North Pacific Ocean as major source of deep water formation for the intermediate-deep waters in the Tethys Basin during the Late Cretaceous.

Deuterium isotope effects on 13C and 15N chemical shifts of intramolecularly hydrogen-bonded enaminocarbonyl derivatives of Meldrum’s and Tetronic acid

NASA Astrophysics Data System (ADS)

Ullah, Saif; Zhang, Wei; Hansen, Poul Erik

2010-07-01

Secondary deuterium isotope effects on 13C and 15N nuclear shieldings in a series of cyclic enamino-diesters and enamino-esters and acyclic enaminones and enamino-esters have been examined and analysed using NMR and DFT (B3LYP/6-31G(d,p)) methods. One-dimensional and two-dimensional NMR spectra of enaminocarbonyl and their deuterated analogues were recorded in CDCl 3 and CD 2Cl 2 at variable temperatures and assigned. 1JNH coupling constants for the derivatives of Meldrum's and tetronic acids reveal that they exist at the NH-form. It was demonstrated that deuterium isotope effects, for the hydrogen bonded compounds, due to the deuterium substitution at the nitrogen nucleus lead to large one-bond isotope effects at nitrogen, 1Δ 15N(D), and two-bond isotope effects on carbon nuclei, 2ΔC(ND), respectively. A linear correlations exist between 2ΔC(ND) and 1Δ 15N(D) whereas the correlation with δNH is divided into two. A good agreement between the experimentally observed 2ΔC(ND) and calculated dσ 13C/dR NH was obtained. A very good correlation between calculated NH bond lengths and observed NH chemical shifts is found. The observed isotope effects are shown to depend strongly on Resonance Assisted Hydrogen bonding.

Allochthonous 2.78 Ga oceanic plateau slivers in a 2.72 Ga continental arc sequence: Vizien greenstone belt, northeastern Superior Province, Canada

NASA Astrophysics Data System (ADS)

Skulski, T.; Percival, J. A.

1996-04-01

Embedded within the vast granitoid terrane of the Minto block of northeastern Superior Province are Late Archean greenstone belts of the Goudalie domain that preserve a long-lived record of continent-ocean interaction. The Vizien greenstone belt is one such belt and it contains four fault-bounded structural panels. The 2786 Ma mafic-ultramafic sequence is an allochthonous package of pillowed basaltic andesite, komatiite and volcaniclastic rocks cut by peridotite and gabbro sills. The mafic rocks are LREE-depleted tholeiites which have primitive mantle (PRIM)-normalized abundances of Th < Nb < La, and ɛNd values of +1.5 to + 3.2 reflecting extraction from a depleted mantle source. The 2724 Ma lac Lintelle continental calc-alkaline volcanic sequence consists of massive basalt, plagioclase-porphyritic andesite, dacite, rhyolite, capped by quartz-rich sandstones/conglomerates with 2.97 Ga Nd model ages. Lac Lintelle volcanic rocks are LREE enriched, with low TiO 2 (< 1%) and Zr (< 200 ppm), PRIM-normalized enrichment in Th > La > Nb, and a range of ɛNd values from -0.1 to +1.7. The ~ 2722 Ma lac Serindac bimodal, subaerial tholeiitic volcanic sequence contains andesite (locally with tonalite xenoliths), basalt, gabbro sills, lenses of quartz-rich sedimentary rocks and a thick, upper rhyolite sequence. The lac Serindac tholeiites are LREE-enriched, have PRIM-normalized Th > La > Nb, high Zr (to 300 ppm) and Ti contents, and low ɛNd values from +0.8 in basalt to -1.4 in rhyolite. The < 2718 Ma basement-cover sequence comprises 2.94 Ga tonalitic gneiss unconformably overlain by clastic sediments and a thin upper sequence of 2700 Ma gabbro, siliceous high-Mg basalt (SHMB) and andesite. The SHMB are characterised by LREE depletion and ɛNd values of +2.6, whereas the andesite is LREE-enriched and has ɛNd values of -0.3. The 2786 Ma mafic-ultramafic sequence is interpreted as a sliver of plume-related oceanic plateau crust. The 2724 lac Lintelle sequence represents a continental arc formed on the eastern protocraton. The ~ 2722 Ma lac Serindac volcanic sequence represents late continental rift deposits. The various 2.8-2.7 Ga supracrustal sequences were accreted, deformed and metamorphosed to mid-amphibolite facies during late-stage assembly of the Minto block between 2.718 and 2.693 Ga.

Laser ion source with solenoid field

NASA Astrophysics Data System (ADS)

Kanesue, Takeshi; Fuwa, Yasuhiro; Kondo, Kotaro; Okamura, Masahiro

2014-11-01

Pulse length extension of highly charged ion beam generated from a laser ion source is experimentally demonstrated. The laser ion source (LIS) has been recognized as one of the most powerful heavy ion source. However, it was difficult to provide long pulse beams. By applying a solenoid field (90 mT, 1 m) at plasma drifting section, a pulse length of carbon ion beam reached 3.2 μs which was 4.4 times longer than the width from a conventional LIS. The particle number of carbon ions accelerated by a radio frequency quadrupole linear accelerator was 1.2 × 1011, which was provided by a single 1 J Nd-YAG laser shot. A laser ion source with solenoid field could be used in a next generation heavy ion accelerator.

Age and origin of anorthosites, charnockites, and granulites in the Central Virginia Blue Ridge: Nd and Sr isotopic evidence

USGS Publications Warehouse

Pettingill, H.S.; Sinha, A.K.; Tatsumoto, M.

1984-01-01

Rb-Sr isotopic data for anorthosites, charnockites, ferrodioritic to quartz monzonitic plutons, and high-grade gneisses of the Blue Ridge of central Virginia show evidence of post-emplacement metamorphism, but in some cases retain Grenville ages. The Pedlar River Charnockite Suite yields an isochron age of 1021 +/-36 Ma, (initial 87Sr/86Sr ratio of 0.7047 +/-6), which agrees with published U-Pb zircon ages. Five samples of that unit which contain Paleozoic mylonitic fabrics define a regression line of 683 Ma, interpreted as a mixing line with no age significance. Samples of the Roseland Anorthosite Complex show excessive scatter on a Rb-Sr evolution diagram probably due to Paleozoic (475 m.y.) metamorphism. Data from the ferrodioritic to quartz monzonitic plutons of the area yield an age of 1009 +/-26 Ma (inital ratio=0.7058 +/-4), which is in the range of the U-Pb zircon ages of 1000-1100 Ma. The Stage Road Layered Gneiss yields an age of 1147 +/-34 Ma (initial ratio of 0.7047 +/- 5). Sm-Nd data for the Pedlar River Charnockite Suite reflect a pre-Grenville age of 1489 +/-118 Ma (e{open}Nd=+6.7 +/-1.2). Data for the Roseland Anorthosite Complex and the ferrodioritic to quartz monzonitic plutons yield Grenville isochron ages of 1045 +/44 Ma (e{open}Nd=+1.0 +/-0.3) and 1027 +/-101 Ma (e{open}Nd=+1.4 +/-1.0), respectively. Two Roseland Anorthosite samples plot far above the isochron, demonstrating the effects of post-emplacement disturbance of Sm-Nd systematics, while mylonitized Pedlar River Charnockite Suite samples show no evidence of Sm-Nd redistribution. The disparity of the Sm-Nd age and other isotopic ages for the Pedlar River Charnockite Suite probably reflects a Sm-Nd "source" age, suggesting the presence of an older crust within this portion of the ca. 1 Ga old basement. ?? 1984 Springer-Verlag.

Petrogenesis of the middle Jurassic appinite and coeval granitoids in the Eastern Hebei area of North China Craton

NASA Astrophysics Data System (ADS)

Fan, Wenbo; Jiang, Neng; Xu, Xiyang; Hu, Jun; Zong, Keqing

2017-05-01

An integrated study of zircon U-Pb ages and Hf-O isotopic compositions, whole rock elemental and Sr-Nd isotope geochemistry was conducted on three lithologically diverse middle Jurassic plutons from the Eastern Hebei area of the North China Craton (NCC), in order to reveal both their petrogenesis and possible tectonic affinity. The three plutons have consistent magmatic zircon U-Pb ages from 167 ± 1 Ma to 173 ± 1 Ma. The Nianziyu pluton has typical characteristics of appinite with low SiO2 (43.7-52.6%), high Ca, Mg, Fe and H2O contents. It possesses subduction-related trace element patterns, enriched Nd-Hf isotopic signatures as well as elevated zircon δ18O values (6.2-7.2‰), arguing for an enriched mantle source metasomatized by fluids related to subduction. The Shuihutong monzogranites have high silica (SiO2 = 75.4-75.9%) and alkali contents, low Ca contents and striking negative Ba, Sr and Eu anomalies. Samples from the pluton have more evolved Nd-Hf isotopic values and are considered to be most likely derived from anatexis of ancient lower continental crust. Hybridization between mantle- and ancient lower crust-derived magmas is proposed for the mafic microgranular enclave-bearing Baijiadian granitoids, which are characterized by variable εNd (t) and εHf(t) values. Integrated with the regional geologic history, we suggest that the formation of the three middle Jurassic plutons were related to the subduction of the Paleo-Pacific ocean plate beneath the NCC. Their petrogenetic differences reflect complex magmatic processes in subduction settings involving melting of multiple sources, possible partly facilitated by fluid metasomatism and water-rich magma injection, accompanied with various degrees of magma mixing. The appearance of middle Jurassic appinitic rocks leads us to propose that the NCC destruction and lithosphere thinning were facilitated and controlled by the weakening of the lithospheric mantle after hydration because of the subduction of the paleo-Pacific ocean plate. The lower crust of the craton was also reactivated at the same time due to the subduction.

Tracking hydrothermal alteration and mineralization in rock-forming and accessory minerals from the Lyon Mountain Granite and related iron oxide apatite (IOA) ores from the Adirondack Mountains, New York State

NASA Astrophysics Data System (ADS)

Buchanan, A.; Hanchar, J. M.; Steele-MacInnis, M. J.; Crowley, J. L.; Valley, P. M.; Fisher, C. M.; Fedo, C.; Piccoli, P. M.; Fournelle, J.

2012-12-01

The Lyon Mountain granite (LMG) is located in the northeastern Adirondack Mountains in New York State and hosts several low-titanium iron oxide apatite (IOA) ore deposits. The ores are predominately hosted by perthite bearing granite, which has been extensively altered to albite and microcline granite by Na and K metasomatism. This alteration results in several distinct groups of rocks that are dominated by either K or Na addition and a group composed of mixed Na and K addition. The different groups of altered perthite also lie on a trend suggestive of addition of Fe to each, consistent with a secondary mineralization origin. Previous work showed that the host rocks of the IOA ores have zircon with ~1150 Ma cores and 1060-1050 Ma rims and whole grains. This study aims to further constrain the timing of LMG emplacement, subsequent hydrothermal alteration, and Fe mineralization through geochemical analysis of the major, minor, and accessory phases and geochronology of accessory phases. SIMS analyses of zircon from several of the IOA ores reveal at least two periods of growth after LMG magmatism, at 1039 +/- 4.4 Ma and 1016 +/- 7 Ma to 1000 +/- 9 Ma. In situ EMPA and LA-ICPMS trace element analyses of the zircon rims and cores reveal that in two samples the zircon rims are enriched in rare earth elements (REE) compared to their cores, potentially pointing to a hydrothermal origin. Apatite has unusually high REE and Y concentrations (some total REE2O3 > 20 wt. % oxide and up to 8 wt. % oxide Y2O3), as does titanite, which allowed for the in situ analysis of Sm-Nd in apatite and titanite by LA-MC-ICP-MS. Initial Nd isotopic composition of both ore and host rock apatite and host rock titanite are consistent with published Adirondack initial Nd whole rock data, suggesting a local source for REE in these ores. EMPA and LA-ICPMS trace-element analyses of the major rock-forming minerals indicate that the feldspar have undergone Na-metasomatism and are depleted in REEs, perhaps signifying the "local source" and the mechanism of the REE enrichment in the LMG apatite in the IOA ores and host rocks. In contrast, the minor- and trace-element compositions of the other major rock-forming minerals (e.g., clinopyroxene and fayalite) as well as the zircon, and fluorite in the LMG have average igneous granitic trace- and minor-element compositions. To better understand the timing and origin of these post ~1050 Ma events, U-Pb ID-TIMS dating of apatite and titanite, and in situ LA-MC-ICPMS Sm-Nd analysis were done on the ore and host rock samples. Apatite dates range from 1050 to 850 Ma and titanite dates range from ~1015 to 970 Ma. There is significant age variation within samples and within grains. Titanite does not have sufficient spread for accurate Sm-Nd isochron dating and two ore-apatite samples have homogenous initial Nd isotopic and Sm-Nd elemental ratios, precluding calculation of Sm-Nd dates. A third ore sample shows a large spread in Sm-Nd and yields a Sm-Nd isochron date of ~850 Ma, in close agreement with U-Pb apatite dates. The Sm-Nd isochron and U-Pb apatite dates may reflect cooling recorded in these minerals or a younger hydrothermal mineralization event.

Application of blind source separation to gamma ray spectra acquired by GRaND around Vesta

NASA Astrophysics Data System (ADS)

Mizzon, H.; Toplis, M. J.; Forni, O.; Prettyman, T. H.; Raymond, C. A.; Russell, C. T.

2012-12-01

The bismuth germinate (BGO) scintillator is one of the sensors of the gamma ray and neutron detector (GRaND)1 on board the Dawn spacecraft, that has spent just over one year in orbit around the asteroid 4-Vesta. The BGO detector is excited by energetic gamma-rays produced by galactic cosmic rays (GCR) or energetic solar particles interacting either with Vesta and/or the Dawn spacecraft. In detail, during periods of quiet solar activity, gamma ray spectra produced by the scintillator can be considered as consisting of three signals: i) a contribution of gamma-rays from Vesta produced by GCR interactions at the asteroid's surface, ii) a contribution from the spacecraft excited by neutrons coming from Vesta, and iii) a contribution of the spacecraft excited by local interaction with galactic cosmic rays. While the first two contributions should be positive functions of the solid angle of Vesta in the field of view during acquisition, the last one should have a negative dependence because Vesta partly shields the spacecraft from GCR. This theoretical mix can be written formally as: S=aΩSV+bΩSSCNV+c(4π-Ω)SSCGCR (1) where S is the series of recorded spectra, Ω is the solid angle, SV is the contribution of gamma rays coming from Vesta, SSCNV is the contribution of gamma rays coming from the spacecraft excited by the neutron coming from Vesta and SSCGCR is the contribution of gamma rays coming from the spacecraft excited by GCR. A blind source separation method called independent component analysis enables separating additive subcomponents supposing the mutual statistical independence of the non-Gaussian source signals2. Applying this method to BGO spectra acquired during the first three months of the low-altitude measurement orbit (LAMO) reveals two main independent components. The first one is dominated by the positron electron annihilation peak and is positively correlated to the solid angle. The second is negatively correlated to the solid angle and displays peaks of elements present in the spacecraft, of energy in the range 1 to 3.5 MeV. At energy >3.5 MeV, the dominant independent component highlighted by this method has no significant peaks, suggesting that it is not influenced by Vesta itself which is known to have a strong signal associated with iron at 7.6 MeV. Our method therefore represents a first step in retrieving the contribution of the spacecraft that could be used in conjunction with the mixing equation (1) to determine the contribution from the planet itself. 1 : Prettyman, T. H., Mcsween, Jr., H. Y., Feldman, W. C., JUN 2010. Dawn's GRaND to map the chemical composition of asteroids Vesta and Ceres. Geochimica and Cosmochimica Acta 74 (12, 1), A832, Con- ference on Goldschmidt 2010 - Earth, Energy, and the Environment, Knoxville, TN, JUN 13-18, 2010. 2 : Hyvarinen, A., Oja, E., May-Jun 2000. Independent component analysis: algorithms and applications. Neural Networks 13 (4-5), 411-430.

The mitochondrial genome of Cethosia biblis (Drury) (Lepidoptera: Nymphalidae).

PubMed

Xin, Tianrong; Li, Lei; Yao, Chengyi; Wang, Yayu; Zou, Zhiwen; Wang, Jing; Xia, Bin

2016-07-01

We present the complete mitogenome of Cethosia biblis (Drury) (Lepidoptera: Nymphalidae) in this article. The mitogenome was a circle molecular consisting of 15,286 nucleotides, 37 genes, and an A + T-rich region. The order of 37 genes was typical of insect mitochondrial DNA sequences described to date. The overall base composition of the genome is A (37.41%), T (42.80%), C (11.87%), and G (7.91%) with an A + T-rich hallmark as that of other invertebrate mitochondrial genomes. The start codon was mainly ATA in most of the mitochondrial protein-coding genes such as ND2, COI, ATP8, ND3, ND5, ND4, ND6, and ND1, but COII, ATP6, COIII, ND4L, and Cob genes employing ATG. The stop codon was TAA in all the protein-coding genes. The A + T region is located between 12S rRNA and tRNA(M)(et). The phylogenetic relationships of Lepidoptera species were constructed based on the nucleotides sequences of 13 PCGs of mitogenomes using the neighbor-joining method. The molecular-based phylogeny supported the traditional morphological classification on relationships within Lepidoptera species.

Synthesis and Characterization of Nanodiamond Reinforced Chitosan for Bone Tissue Engineering

PubMed Central

Sun, Yu; Yang, Qiaoqin; Wang, Haidong

2016-01-01

Multifunctional tissue scaffold material nanodiamond (ND)/chitosan (CS) composites with different diamond concentrations from 1 wt % to 5 wt % were synthesized through a solution casting method. The microstructure and mechanical properties of the composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and nanoindentation. Compared with pristine CS, the addition of ND resulted in a significant improvement of mechanical properties, including a 239%, 276%, 321%, 333%, and 343% increase in Young’s modulus and a 68%, 96%, 114%, 118%, and 127% increase in hardness when the ND amount was 1 wt %, 2 wt %, 3 wt %, 4 wt %, and 5 wt %, respectively. The strong interaction between ND surface groups and the chitosan matrix plays an important role in improving mechanical properties. PMID:27649252

Distribution and Fate of Energetics on DoD Test and Training Ranges

DTIC Science & Technology

2004-11-01

766 ND ND ND 1,2,4-Tdchlorobenzene pg/L 0 954 ND ND ND 1,2-Dibromo-3- Chloropropane pg/L 1 766 0.60 0.60 0.60 1,2-Dibromoethane (Ethylene Dibromide) pg...xxii 1 - Introduction .................................................................................................. 1 - 1 Background... 1 - 1 Scope of Project CP 1155

Ultra-high precision 142Nd/144Nd measurements of the Proterozoic and implications for mixing in the Earth's mantle through time

NASA Astrophysics Data System (ADS)

Hyung, E.; Jacobsen, S. B.

2017-12-01

The decay of 146Sm to 142Nd is an excellent a tracer for early silicate differentiation events in the terrestrial planets, as the Sm/Nd ratio is usually fractionated during mantle partial melting and magma ocean crystallization. The short half-life (103 or 68 Ma) renders the system extinct within the first 500 Ma of Solar System formation. Samples with 142Nd/144Nd ratios that are substantially different from the bulk silicate Earth value of 142Nd/144Nd provide clear evidence for mantle differentiation in the Hadean. Published data for the 3.4 to 3.8 Ga old Isua supracrustal rocks and dykes have demonstrated both positive and negative 142Nd/144Nd anomalies (30 ppm range) providing clear evidence for Hadean enriched and depleted mantle reservoirs. In contrast, no 142Nd/144Nd anomalies have been found in modern day terrestrial samples with data that have 2σ uncertainties of about 5 ppm or more. Last year we reported improvements in 142Nd/144Nd measurements, using our IsotopX thermal ionization mass spectrometer, and obtained reproducibility of 142Nd/144Nd ratios to better than 2 ppm at the 2σ level. With this external reproducibility we found that all except one modern mantle-derived basalt had within error identical 142Nd/144Nd ratios. One sample is about 3.4 ppm lower than the rest of the modern basalt samples, providing evidence for some limited Hadean mantle differentiation signatures preserved up to present. We have also measured 142Nd/144Nd ratios for Proterozoic and Phanerozoic samples, whose ages range from 300 Ma to 2 Ga, to better than 2 ppm external reproducibility (2σ). Most of these samples also have 142Nd/144Nd ratios that cluster around the modern day value, but there are some samples that are either marginally high by 2 ppm or low by 2 ppm. Thus, while a 20 to 30 ppm range in 142Nd/144Nd is well resolved in the Archean, such large variability is not present in the Proterozoic and Phanerozoic. The relatively rapid changeover at the end of the Archean has important implications for understanding the mixing rate of the mantle through time.

1.5  kW efficient CW Nd:YAG planar waveguide MOPA laser.

PubMed

Wang, Juntao; Wu, Zhenhai; Su, Hua; Zhou, Tangjian; Lei, Jun; Lv, Wenqiang; He, Jing; Xu, Liu; Chen, Yuejian; Wang, Dan; Tong, Lixin; Hu, Hao; Gao, Qingsong; Tang, Chun

2017-08-15

In this Letter, we report a 1064 nm continuous wave Nd:YAG planar waveguide laser with an output power of 1544 W based on the structure of the master oscillator power amplification. A fiber laser is used as the master oscillator, and diode laser arrays are used as the pump source of the waveguide laser amplifier. The dimension of the waveguide is 1  mm (T)×10  mm (W)×60  mm (L), and the dual end oblique pumping is adopted with different angles. After a single-pass amplification, the power is scaled from 323 to 1544 W with the pump power of 2480 W, leading to an optical-to-optical efficiency of 49%. At the maximum output, the beam quality M 2 are measured to be 2.8 and 7.0 in the guided direction and the unguided direction, respectively. To the best of our knowledge, this is the highest output power of a Nd:YAG planar waveguide laser to date.

Concordant Rb-Sr and Sm-Nd Ages for NWA 1460: A 340 Ma Old Basaltic Shergottite Related to Lherzolitic Shergottites

NASA Technical Reports Server (NTRS)

Nyquist, L. E.; Shih, C-Y; Reese, Y. D.; Irving, A. J.

2006-01-01

Preliminary Rb-Sr and Sm-Nd ages reported by [1] for the NWA 1460 basaltic shergottite are refined to 336+/-14 Ma and 345+/-21 Ma, respectively. These concordant ages are interpreted as dating a lava flow on the Martian surface. The initial Sr and Nd isotopic compositions of NWA 1460 suggest it is an earlier melting product of a Martian mantle source region similar to those of the lherzolitic shergottites and basaltic shergottite EETA79001, lithology B. We also examine the suggestion that generally "young" ages for other Martian meteorites should be reinterpreted in light of Pb-207/Pb-206 - Pb-204/Pb-206 isotopic systematics [2]. Published U-Pb isotopic data for nakhlites are consistent with ages of approx.1.36 Ga. The UPb isotopic systematics of some Martian shergottites and lherzolites that have been suggested to be approx.4 Ga old [2] are complex. We nevertheless suggest the data are consistent with crystallization ages of approx.173 Ma when variations in the composition of in situ initial Pb as well as extraneous Pb components are considered.

Geochemical and isotopic constraints on island arc, synorogenic, post-orogenic and anorogenic granitoids in the Arabian Shield, Saudi Arabia

NASA Astrophysics Data System (ADS)

Robinson, F. A.; Foden, J. D.; Collins, A. S.

2015-04-01

The Arabian Shield preserves a protracted magmatic record of repeated amalgamation of juvenile subduction terranes that host granite intrusions ranging in age from the early Neoproterozoic to the Cambrian, which were emplaced into convergent and within-plate settings. Geochronology and whole-rock geochemistry of sampled Saudi Arabian granitoids define and distinguish four discrete age groups: 1) ~ 845-700 Ma island arc and synorogenic granitoids (IA + Syn), 2) ~ 640-610 Ma granitoids from the Nabitah and Halaban Suture (NHSG), 3) ~ 610-600 Ma post-orogenic perthitic (hypersolvus) granitoids (POPG), and 4) < 600 Ma anorogenic aegirine-bearing perthitic (hypersolvus) granitoids (AAPG). Groups 1, 2 and 3 include suites ranging from I-S- to A-type granites that have REE signatures typical of volcanic arc settings and show intra-suite variation that could be controlled by a combination of crustal assimilation and fractional crystallisation. Their mafic parental magmas have N-MORB-, or arc-tholeiite-like geochemistry. By contrast, group 4 A-type granites are more enriched in HREE and in incompatible elements such as Nb, Rb, Ga, Nd, Zr and Y and have lower Ce/Yb and higher Y/Nb ratios. These granitoids are interpreted to have been emplaced into within-plate and back-arc settings. Granitoid data also provide evidence that there may be two distinct mantle sources to the mafic parents of the granite suites. These are distinguished as contaminated and enriched mantle using Nb and Y and Nd isotopes. All granitoid suites are isotopically juvenile (ɛNd + 3 to + 6) and fall between the upper field crustal values of the Paleoproterozoic Khida terrane (ɛNd + 1) and contemporary depleted mantle. However, Nd isotopes distinguish contamination in group 1-3 mafic end-members beneath sutures which are interpreted to be derived from the contemporary MORB-type mantle wedge with subsequent crustal assimilation and fractionation to I- and A-type granitoids. The youngest (after 600 Ma) A-types (group 4) emplaced into extensional within-plate and back-arc settings require a new enriched mantle source that this study interprets to be associated with delamination.

Cerium and Neodymium Isotope Fractionation in Geochemical Samples

NASA Astrophysics Data System (ADS)

Ohno, T.; Ishibashi, T.

2014-12-01

The study of naturally occurring isotopic variations of rare earth elements (REE) has a potentially significant influence in geochemical research fields with other traditional studies of REE. One of the key features of REE are their chemical similarities and gradual changes of ionic radius, which may make the isotopic variation of REE a potential tool to understand the mechanisms of isotopic fractionation in nature. Among the REE, geochemical and physicochemical features of Ce could be anomalous, because Ce could be present as the tetravalent (+IV) state as well as the common trivalent (+III) state of other REE. Since the oxidation state of Ce can change by reflecting the redox conditions of the environment, the measured differences in the degree of isotopic fractionation between Ce and other REE can provide unique information about the redox conditions. In this study, we developed a new analytical method to determine the mass-dependent isotopic fractionations of Ce and Nd in geochemical samples. The reproducibility of the isotopic ratio measurements on 142Ce/140Ce, 146Nd/144Nd and 148Nd/144Nd were 0.08‰ (2SD, n=25), 0.06‰ (2SD, n=39) and 0.12‰ (2SD, n=39), respectively. The present technique was applied to determine the variations of the Ce and Nd isotopic ratios for five geochemical reference materials (igneous rocks, JB-1a and JA-2; sedimentary rocks, JMn-1, JCh-1 and JDo-1). The resulting ratios for two igneous rocks (JB-1a and JA-2) and two sedimentary rocks (JMn-1 and JCh-1) did not vary significantly among the samples, whereas the Ce and Nd isotope ratios for the carbonate samples (JDo-1) were significantly higher than those for igneous and sedimentary rock samples. The 1:1 simple correlation between δ142Ce and δ146Nd indicates that there were no significant difference in the degree of isotopic fractionation between the Ce and Nd. This suggests that the isotopic fractionation for Ce found in the JDo-1 could be induced by physicochemical processes without changing the oxidation status of Ce, since the redox-reaction can produce larger isotopic fractionation than the reactions without changing the oxidation state. The variations in the Ce and Nd isotope ratios for geochemical samples could provide new information concerning the physico-chemical processes of the sample formation.

The 48 Ma Koko Guyot: Early Indications of Temporal Changes in the Composition of the Hawaiian Plume?

NASA Astrophysics Data System (ADS)

Thompson, P. M.; Kempton, P. D.; Saunders, A. D.

2002-12-01

The 48 Ma Koko Guyot is the youngest Emperor Seamount drilled during ODP Leg 197. Leg 197 drilled 278 m into a sequence of 15 lava flows and hyaloclastites, with subordinate amounts of volcaniclastic sandstone and limestone. The sampled lava flows are mainly tholeiitic to transitional basalts and dolerites, with some intercalated alkalic basalts. Thus, the lavas sampled at Koko Guyot resemble the late shield stage of a modern-day Hawaiian volcano, being dominantly tholeiitic in character. The alkalic basalts generally display higher Zr and TiO2 for a given MgO compared to the tholeiites. The degree of scatter for most incompatible elements when plotted against MgO implies that the lavas do not define one liquid line of descent: several parent magma compositions must therefore be invoked. The lavas from Koko have Sr, Nd, Pb and Hf isotope compositions that are the most Hawaiian-like of the Emperor Seamounts that have been studied, displaying similar ɛ Nd to Mauna Kea. Our new data are consistent with the suggestion from trace elements that several different source compositions are required in the genesis of the Koko lavas. The involvement of at least two components is suspected from the apparently linear array in ɛ Hf-ɛ Nd space, which is also indicated by Pb and Sr isotope data. This linear array in ɛ Hf-ɛ Nd space defines a steeper slope than that of Recent Hawaiian magma types, which suggests a fundamental source difference between Koko and modern-day Hawaii. The shallower slope of Hawaiian volcanoes is thought to indicate the involvement of recycled pelagic sediment in the genesis of Hawaiian lavas (Blichert-Toft et al., 1999). Thus, preliminary data from the Koko Guyot suggest that the composition of the Hawaiian plume has changed in composition over time. The causes of this temporal variation are unknown, but may result from changes in the amount of pelagic sediment recycled from the deep plume source. Blichert-Toft, J., Frey, F.A. and Albarède, F., 1999. Hf isotope evidence for pelagic sediments in the source of Hawaiian basalts. Science, 285, 879-882.

Promoting Decision-Making Skills by Youth with Disabilities: Health, Education, and Vocational Choices. 2nd Edition. CYDLINE Reviews.

ERIC Educational Resources Information Center

Minnesota Univ., Minneapolis. National Center for Youth with Disabilities.

This annotated bibliography offers background information and resource information on decision-making issues for young adults with chronic conditions. The bibliography includes books, journal articles, booklets, audiotapes, and videotapes. For each item listed in the bibliography, the following information is provided: author; title; source; and…

American Indian Studies. Library Research Guide. 2nd Edition.

ERIC Educational Resources Information Center

White, Phillip M.

This guide to sources for San Diego (California) State University students doing library research on topics related to American Indian Studies begins by noting that information on North American Indians can be found in a variety of subject disciplines including history, anthropology, education, sociology, health care, law, business, and politics.…

Nuclear Energy Research Initiative (NERI) Program. 2nd Quarterly Technical Progress Report

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

NONE

2000-02-22

The research activities have been underway. We have located a large body of source material from aerospace, shipbuilding and manufacturing businesses that is serving the basis for identifying improvement methodologies. Our work on developing the three models proposed to capture the extent of the improvement possibilities has been ongoing.

Selecting Stories for Multicultural Art Lessons (Kindergarten-2nd Grade Emphasis).

ERIC Educational Resources Information Center

DiSiena, Julie

Storytelling has cultural roots and this can be employed to teach a culturally pluralistic curriculum. Stories can be selected from a variety of sources and used to match lesson objectives. Criteria for selecting stories should include the authenticity of cultural representation, the amount of cultural information, appropriateness, and the…

On Sources of the Word Length Effect in Young Readers

ERIC Educational Resources Information Center

Gagl, Benjamin; Hawelka, Stefan; Wimmer, Heinz

2015-01-01

We investigated how letter length, phoneme length, and consonant clusters contribute to the word length effect in 2nd- and 4th-grade children. They read words from three different conditions: In one condition, letter length increased but phoneme length did not due to multiletter graphemes (H"aus"-B"auch"-S"chach"). In…

Vibration-based photoacoustic tomography

NASA Astrophysics Data System (ADS)

Li, Rui; Rajian, Justin R.; Wang, Pu; Slipchenko, Mikhail N.; Cheng, Ji-Xin

2013-03-01

Photoacoustic imaging employing molecular overtone vibration as contrast mechanism opens a new avenue for deep tissue imaging with chemical bond selectivity. Here, we demonstrate vibration-based photoacoustic tomography with an imaging depth on the centimeter scale. To provide sufficient pulse energy at the overtone transition wavelengths, we constructed a compact, barium nitrite crystal-based Raman laser for excitation of 2nd overtone of C-H bond. Using a 5-ns Nd:YAG laser as pumping source, up to 105 mJ pulse energy at 1197 nm was generated. Vibrational photoacoutic spectroscopy and tomography of phantom (polyethylene tube) immersed in whole milk was performed. With a pulse energy of 47 mJ on the milk surface, up to 2.5 cm penetration depth was reached with a signal-to-noise ratio of 12.

Establishment of the 2nd Korean national biological reference standard for blood coagulation factor VIII:C concentrate.

PubMed

Lee, Naery; Seo, Ji Suk; Kim, Jae Ok; Ban, Sang Ja

2017-05-01

Since the 1st Korean national biological reference standard for factor (F)VIII concentrate, established in 2001, has shown declining potency, we conducted this study to replace this standard with a 2nd Korean national biological reference standard for blood coagulation FVIII concentrate. The candidate materials for the 2nd standard were prepared in 8000 vials with 10 IU/ml of target potency, according to the approved manufacturing process of blood coagulation Factor VIII:C Monoclonal Antibody-purified, Freeze-dried Human Blood Coagulation Factor VIII:C. Potency was evaluated by one-stage clotting and chromogenic methods and the stability was confirmed to meet the specifications during a period of 73 months. Since the potencies obtained by the two methods differed significantly (P < 0.015), the values were determined separately according to the geometric means (8.9 and 7.4 IU/vial, respectively). The geometric coefficients of interlaboratory variability were 3.4% and 7.6% by the one-stage clotting and chromogenic assays, respectively. Copyright © 2017 International Alliance for Biological Standardization. Published by Elsevier Ltd. All rights reserved.

Tailoring Nd3+ emission spectrum by a neodymium-doped tellurite all-solid photonic bandgap fiber

NASA Astrophysics Data System (ADS)

Tong, Hoang Tuan; Demichi, Daisuke; Suzuki, Takenobu; Ohishi, Yasutake

2018-02-01

A tellurite all-solid photonic bandgap fiber (ASPBF) whose cladding consists of 60 high-index rods arranged periodically around a central core was successfully fabricated. The diameter of high-index rod was about 5.0 μm and the distance between the center of two adjacent high-index rods was approximately 8.0 μm. The high-index rod was made of the TeO2-Li2O-WO3-MoO3-Nb2O5 (TLWMN) glass, the cladding was made of the TeO2-ZnO-Na2O-La2O3 (TZNL) glass as the background glass material and the central core was made of TZNL glass doped with 0.5 wt% of Nd2O3. A supercontinuum light from 0.6 to 2.4 μm was coupled into the core of fiber which is 2.2 cm long to measure its transmission spectrum. High transmission bands were obtained in the vicinity of 0.75 and 1.3 μm but the transmission was suppressed in the wavelength range from 1.0 to 1.06 μm. When a titanium∶Sapphire laser source at 0.75 μm was used, the emission spectrum was obtained with two peaks at 1.06 and 1.33 μm which are attributed to the 4F3/2->4I11/2 and 4F3/2->4I13/2 transitions of Nd3+ ion, respectively. The intensities of those emission peaks were compared with those obtained from a bulk glass having the same doping concentration of Nd3+. The results showed that by using tellurite ASPBF, the intensity of the 1.06-μm emission was suppressed by one-twelfth but the intensity of the 1.33-μm emission was maintained. This feature is very advantageous to filter out the 1.06-μm emission of Nd3+ ion in order to realize practical amplifier devices at 1.3 μm.

The complete mitochondrial genome of the giant African snail Achatina fulica (Mollusca: Achatinidae).

PubMed

Yang, Huirong; Zhang, Jia-En; Guo, Jing; Deng, Zhixin; Luo, Hao; Luo, Mingzhu; Zhao, Benliang

2016-05-01

We present the complete mitochondrial genome of the Achatina fulica in this study. The results show that the mitochondrial genome is 15,057 bp in length, which is comprised of 13 protein-coding genes, 2 rRNA genes, 21 tRNA genes. The nucleotide compositions of the light strand are 35.47% of A, 27.97% of T 19.46% of C, and 17.10% of G. Except the ND3, 7 tRNA, ATP6, ATP8, COX3 and 12S-rRNA on the light strand, the rest are encoded on the heavy strand. Five types of inferred initiation codons are ATA (ND1, ND5), GTG (ND6), ATG (COX3, COX2), ATT (ND4) and TTG (COX1, ND2, ND3, ND4L, ATP6, ATP8, Cytb), and 3 types of inferred termination codons are T (COX3, ND2), TAA (ND1, ND4L, ND5, ND6, ATP6), and TAG (ND3, ND4, COX1, COX2, Cytb, ATP8). There are 24 intergenic spacers and 6 gene overlaps. The tandem repeat sequence (total 52 bp) of (AATAATT)n is observed in 16S-rRNA. Gene arrangement and distribution are inconsistent with the typical vertebrates.

Optical and structural properties of Nd:MgO:LiNbO3 crystal irradiated by 2.8-MeV He ions

NASA Astrophysics Data System (ADS)

Jia, Chuan-Lei; Li, Song; Song, Xiao-Xiao

2017-07-01

We report the optical and structural properties of helium-implanted optical waveguides in Nd:MgO:LiNbO3 laser crystals. The prism-coupling method is used to investigate the dark-mode properties at the wavelength of 632.8 nm. The spontaneous generation of ultraviolet, blue, red, and near-infrared fluorescence emissions is demonstrated under excitation with an 808-nm laser diode. The effects of ion irradiation on the structural properties are characterized using the high-resolution X-ray diffraction technique. The results show that the initial luminescence properties of Nd:MgO:LiNbO3 crystals are slightly modified by irradiation with 2.8 MeV He ions at fluences of 1.5 × 1016 ions/cm2 at room temperature.

Fully non-inductive second harmonic electron cyclotron plasma ramp-up in the QUEST spherical tokamak

NASA Astrophysics Data System (ADS)

Idei, H.; Kariya, T.; Imai, T.; Mishra, K.; Onchi, T.; Watanabe, O.; Zushi, H.; Hanada, K.; Qian, J.; Ejiri, A.; Alam, M. M.; Nakamura, K.; Fujisawa, A.; Nagashima, Y.; Hasegawa, M.; Matsuoka, K.; Fukuyama, A.; Kubo, S.; Shimozuma, T.; Yoshikawa, M.; Sakamoto, M.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Ide, S.; Maekawa, T.; Takase, Y.; Toi, K.

2017-12-01

Fully non-inductive second (2nd) harmonic electron cyclotron (EC) plasma current ramp-up was demonstrated with a newlly developed 28 GHz system in the QUEST spherical tokamak. A high plasma current of 54 kA was non-inductively ramped up and sustained stably for 0.9 s with a 270 kW 28 GHz wave. A higher plasma current of 66 kA was also non-inductively achieved with a slow ramp-up of the vertical field. We have achieved a significantly higher plasma current than those achieved previously with the 2nd harmonic EC waves. This fully non-inductive 2nd harmonic EC plasma ramp-up method might be useful for future burning plasma devices and fusion reactors, in particular for operations at half magnetic field with the same EC heating equipment.

Critical behavior near the ferromagnetic phase transition in double perovskite Nd2NiMnO6

NASA Astrophysics Data System (ADS)

Ali, Anzar; Sharma, G.; Singh, Yogesh

2018-05-01

The knowledge of critical exponents plays a crucial role in trying to understand the interaction mechanism near a phase transition. In this report, we present a detailed study of the critical behaviour near the ferromagnetic (FM) transition (TC ˜ 193 K) in Nd2NiMnO6 using the temperature and magnetic field dependent isothermal magnetisation measurements. We used various analysis methods such as Arrott plot, modified Arrott plot, and Kouvel-Fisher plot to estimate the critical parameters. The magnetic critical parameters β = 0.49±0.02, γ = 1.05±0.04 and critical isothermal parameter δ = 3.05±0.02 are in excellent agreement with Widom scaling. The critical parameters analysis emphasizes that mean field interaction is the mechanism driving the FM transition in Nd2NiMnO6.

Fast coincidence counting with active inspection systems

NASA Astrophysics Data System (ADS)

Mullens, J. A.; Neal, J. S.; Hausladen, P. A.; Pozzi, S. A.; Mihalczo, J. T.

2005-12-01

This paper describes 2nd and 3rd order time coincidence distributions measurements with a GHz processor that synchronously samples 5 or 10 channels of data from radiation detectors near fissile material. On-line, time coincidence distributions are measured between detectors or between detectors and an external stimulating source. Detector-to-detector correlations are useful for passive measurements also. The processor also measures the number of times n pulses occur in a selectable time window and compares this multiplet distribution to a Poisson distribution as a method of determining the occurrence of fission. The detectors respond to radiation emitted in the fission process induced internally by inherent sources or by external sources such as LINACS, DT generators either pulsed or steady state with alpha detectors, etc. Data can be acquired from prompt emission during the source pulse, prompt emissions immediately after the source pulse, or delayed emissions between source pulses. These types of time coincidence measurements (occurring on the time scale of the fission chain multiplication processes for nuclear weapons grade U and Pu) are useful for determining the presence of these fissile materials and quantifying the amount, and are useful for counter terrorism and nuclear material control and accountability. This paper presents the results for a variety of measurements.

Efficient reuse of the waste sintered NdFeB magnet with Dy2O3 addition

NASA Astrophysics Data System (ADS)

Li, Chencheng; Sun, Aizhi; Tian, Zhenya; Zhang, Xun; Ma, Bin

2018-09-01

In this paper, the efficient recycling method of sintered NdFeB waste was studied. The production process can be greatly simplified by crushing the recovered waste magnet into hundreds of micron-sized magnetic powder and preparing the magnet directly with orientating, molding and sintering. The magnetic properties of the magnet prepared by commercial N45 recovered waste can reach Br = 1.09 T, (BH)max = 196 kJ/m3 and Hcj = 601 kA/m. Adding a small amount of Dy2O3 can significantly improve the Br of the above magnet. The maximum Hcj can reach 1310 kA/m and (BH)max can reach 204 kJ/m3. The microstructure analysis shows that Dy2O3 diffused along the grain boundaries mainly and forms Dy-rich shell around the Nd2Fe14B grains which increase the difficulty of forming anti-magnetization.

U-Pbdating on detrital zircon and Nd and Hf isotopes related to the provenance of siliciclastic rocks of the Amazon Basin: Implications for the origin of Proto-Amazonas River

NASA Astrophysics Data System (ADS)

Dantas, Elton Luiz; Silva Souza, Valmir; Nogueira, Afonso C. R.; Ventura Santos, Roberto; Poitrasson, Franck; Vieira Cruz, Lucieth; Mendes Conceição, Anderson

2014-05-01

Previous provenance studies along the Amazonas river have demonstrated that the Amazon drainage basin has been reorganized since the Late Cretaceous with the uplift of the Andes and the establishment of the transcontinental Amazon fluvial system from Late Miocene to Late Pleistocene (Hoorn et al., 1995; Potter, 1997, Wesselingh et al., 2002; Figueiredo et al. 2009, Campbell et al., 2006, Nogueira et al. 2013).There is a lack of data from Eastern and Central Amazonia and only limited core data from the Continental Platform near to current Amazonas river mouth. Central Amazonia is strategic to unveil the origin of Amazonas River because it represents the region where the connection of the Solimões and Amazonas basin can be studied through time (Nogueira et al. 2013). Also, there is a shortage of information on the old Precambrian and Paleozoic sediment sources relative to Cretaceous and Miocene siliciclastic deposits of the Solimões and Amazonas basins. We collected stratigraphic data, detrital zircon U-Pb ages and Nd and Hf isotopes from Precambrian, Paleozoic, Cretaceous and Miocene siliciclastic deposits of the Northwestern border of Amazonas Basin. They are exposed in the Presidente Figueiredo region and in the scarps of Amazon River, and occur to the east of the Purus Arch. This Northwest-Southeast trending structural feature that divides the Solimões and Amazonas basin was active at various times since the Paleozoic. Detrital zircon ages for the Neoproterozoic Prosperança Formation yielded a complex signature, with different populations of Neoproterozoic (550, 630 and 800 Ma) and Paleoproterozoic to Archean sources (1.6, 2.1 and 2.6 Ga). Also Nd and Hf isotopes show two groups of TDM model ages between 1.4 to 1.53 Ga and 2.2 and 3.1 Ga. Sediments typical of Paleozoic sedimentary rocks of the Nhamundá and Manacapuru Formations revealed NdTDM model ages of 1.7, 2.2 and 2.7 Ga, but Hf isotopes and U-Pb zircon ages are more varied. They characterize a provenance dominated by Mesoproterozoic sources (1.0, 1.2 Ga) and subordinate Neoproterozoic(550-800 Ma) and Archean derivation (2.67 Ga). On the other hand, detrital zircon and Hf and NdTDM model ages for the Cretaceous Alter do Chão Formation yielded a unique Paleoproterozoicages between 2.0 and 2.3 Ga that can be correlated to sources derived from Maroni-Itacaiúnas and Central Amazonian basement provinces. The contribution of Precambrian and Paleozoic rocks exposed during the installationof the Amazonas drainage were probably significant .Such a large contribution from Neoproterozoic and Mesoproterozoic sources are not common in the proximal Amazon Craton basement .This new proposal open new perspectives to understand better the initial history of Amazon River with indication of the probable source areas during Late Cenozoic. Campbell Jr.; Frailey,C.D.; Romero-Pittman, G. 2006. The Pan-Amazonian UcayliPeneplain, late Neogenesedimentacion in Amazonia, and the Birth on the Modern Amazon River system.Palaeogeography,Palaeoclimatology, Palaeoecology. 239 (2006) 166-219 Figueiredo, J.,Hoorn, C., Van der Vem, P., Soares, E. 2009. Late Miocene onset of the Amazon River and the Amazon deep-sea fan: Evidence from the Fozdo Amazonas Basin. Geology, 37(7):619-622. Hoorn,C.; Guerrero, J.; Sarmiento, G. 1995. Andean tectonics as a cause for changing drainage patterns in Miocene Northern South America. Geology, v.23, p-237-240. Nogueira, A.C.R.; Silveira, R.R.; Guimarães, J.T.F. 2013. Neogene-Quaternary sedimentary and paleovegetation history of the eastern Solimões Basin, central Amazon region.Journal of South American Earth Sciences , v. 46, p. 89-99, 2013. Potter, P.E. 1997. The Mesozoic and Cenozoic paleodrainage of South America: a natural history. Journal of South American Earth Science.v.10. p.331-344 Wesselingh, F. P., et al., 2002. Lake-Pebas: a palaeocological reconstruction of a Miocene long-lived lake comples in Western Amazônia. Cainozoic Research 1 (1-2), 35-81.

Plio-Pleistocene evolution of water mass exchange and erosional input at the Atlantic-Arctic gateway

NASA Astrophysics Data System (ADS)

Teschner, Claudia; Frank, Martin; Haley, Brian A.; Knies, Jochen

2016-05-01

Water mass exchange between the Arctic Ocean and the Norwegian-Greenland Seas has played an important role for the Atlantic thermohaline circulation and Northern Hemisphere climate. We reconstruct past water mass mixing and erosional inputs from the radiogenic isotope compositions of neodymium (Nd), lead (Pb), and strontium (Sr) at Ocean Drilling Program site 911 (leg 151) from 906 m water depth on Yermak Plateau in the Fram Strait over the past 5.2 Myr. The isotopic compositions of past bottom waters were extracted from authigenic oxyhydroxide coatings of the bulk sediments. Neodymium isotope signatures obtained from surface sediments agree well with present-day deepwater ɛNd signature of -11.0 ± 0.2. Prior to 2.7 Ma the Nd and Pb isotope compositions of the bottom waters only show small variations indicative of a consistent influence of Atlantic waters. Since the major intensification of the Northern Hemisphere Glaciation at 2.7 Ma the seawater Nd isotope composition has varied more pronouncedly due to changes in weathering inputs related to the waxing and waning of the ice sheets on Svalbard, the Barents Sea, and the Eurasian shelf, due to changes in water mass exchange and due to the increasing supply of ice-rafted debris (IRD) originating from the Arctic Ocean. The seawater Pb isotope record also exhibits a higher short-term variability after 2.7 Ma, but there is also a trend toward more radiogenic values, which reflects a combination of changes in input sources and enhanced incongruent weathering inputs of Pb released from freshly eroded old continental rocks.

A new method to solve the Nd breakup scattering problem in configuration space

NASA Astrophysics Data System (ADS)

Suslov, Vladimir

2005-11-01

A new computational method for solving the configuration-space Faddeev equations for three nucleon system has been developed. This method is based on the spline-decomposition in the angular variable and a generalization of the Numerov method for the hyperradius. The s-wave calculations of the inelasticity and phase-shift, as well as breakup amplitudes for nd and pd breakup scattering for lab energies 14.1 and 42.0 MeV were performed with the Malfliet -Tjon MT I-III potential. In the case of nd breakup scattering the results are in good agreement with those of the benchmark solution [1],[2]. In the case of pd quartet breakup scattering disagreement for the inelasticities reaches up to 6% as compared with those of the Pisa group [3]. The calculated pd amplitudes fulfill the optical theorem with a good precision. 1. J. L. Friar, B. F. Gibson, G. Berthold, W. Gloeckle, Th. Cornelius, H. Witala, J. Haidenbauer, Y. Koike, G. L. Payne, J. A. Tjon, and W. M. Kloet,: http://link.aip.org/link/?&lcreator=getabs-normal&ldir=FWD&lrel=CITES&fromkey=PRVCAN000069000004044003000001&fromkeyType=CVIPS&fromloc=AIP&toj=PRVCAN&tov=42&top=1838&toloc=APS&tourl=http%3A%2F%2Flink.aps.org%2Fabstract%2FPRC%2Fv42%2FPhys. Rev. C 42, 1838 (1990). 2. Frair J.L, Payne G.L., Gl"ockle W., Hueber D., Witala H.: Phys. Rev. C 51, 2356 (1995) 3. Kievsky A., Viviani M., and Rosati S.: Phys. Rev. C 64, 024002 (2001)

The Origin of EM1 Signatures in Basalts From Tristan da Cunha and Gough

NASA Astrophysics Data System (ADS)

Stracke, A.; Willbold, M.; Hemond, C.

2004-12-01

A long-standing hypothesis is that enriched mantle 1 (EM-1)-type ocean island basalt (OIB) sources contain pelagic sediments. Pelagic sediments range in composition from clays to calcareous or siliceous oozes and encompass a wide range of chemical compositions [1]. For geochemical purposes the use of the term pelagic sediments is often restricted to a special group of pelagic sediments with distinctive enrichment of Rare Earth Elements (REE). The geochemical composition of such REE-enriched pelagic sediments, however, is by no means representative of the geochemical composition of pelagic sediments in general. The extremely high REE/non-REE element ratios in REE-enriched pelagic sediments (e.g. high Lu/Hf, Sm/Hf, La/Nb, La/Th, Eu/Ti, and Gd/Ti ratios) translate into high 176Hf/177Hf ratios for given 143Nd/144Nd ratios with time. OIB sources containing this special variety of REE-enriched pelagic sediment should therefore plot above the oceanic basalt array and mixing arrays with these sources are expected to have a shallow slope in a Hf-Nd isotope diagram. Here we present new Hf-Nd isotope and trace element data for EM-1-type OIB from Tristan da Cunha and Gough in the South Atlantic Ocean. The samples from Tristan have a small range in Hf-Nd isotopic composition and plot within the oceanic basalt array in a Hf-Nd isotope diagram. Samples from Gough form a trend with a slope slightly steeper than that of the ocean basalt array in a Hf-Nd isotope diagram. OIB in general have a very restricted range in Gd/Ti and Sm/Hf ratios, and high La/Nb are associated with low Lu/Hf ratios. In detail, samples from Tristan and Gough have the lowest Lu/Hf and highest La/Nb ratios. Thus from the combined Hf-Nd isotope and trace element composition of basalts from Tristan and Gough involvement of this special variety of (REE-enriched) pelagic sediments can be excluded. Similar observations are made, and thus similar arguments hold, for other EM-1-type localities (Walvis ridge [2] and Pitcairn island [3]). Due to the considerable spread in geochemical composition of pelagic or any other group of sediments (e.g. marine sediments with a higher proportion of terrigenous components), it is difficult to attribute characteristic elemental or isotopic signatures to certain groups of sediment. Moreover, subducting sediments are complex mixtures of different types of sediment [1]. Thus it is difficult to find unique evidence either in favor of or against the involvement of sediments in general at Tristan and Gough, or any other individual OIB locality. Also, it appears highly unlikely that sub-arc processing has an equalizing effect on the composition of different subducting sediments [4]. Associating the similar isotopic characteristics of certain OIB groups and/or mantle-end-members (e.g. EM-1) to recycled sediments is therefore also problematic. [1] Plank, T. and C. H. Langmuir, Chem. Geol., 145, 325-394, 1998. [2] Salters, V. J. M. and X. Li, Geochim. Cosmochim. Acta, 68, A554, 2004. [3] Eisele, J., M. Sharma, J. G. Galer, J. Blichert-Toft, C. W. Devey and A. W. Hofmann, Earth Plan. Sci. Lett., 196, 197-212, 2002. [4] Johnson, M. C. and T. Plank, Geochem., Geophys., Geosys., 1, pp. 29, 1999.

Nanodiamonds on tetrahedral amorphous carbon significantly enhance dopamine detection and cell viability.

PubMed

Peltola, Emilia; Wester, Niklas; Holt, Katherine B; Johansson, Leena-Sisko; Koskinen, Jari; Myllymäki, Vesa; Laurila, Tomi

2017-02-15

We hypothesize that by using integrated carbon nanostructures on tetrahedral amorphous carbon (ta-C), it is possible to take the performance and characteristics of these bioelectrodes to a completely new level. The integrated carbon electrodes were realized by combining nanodiamonds (NDs) with ta-C thin films coated on Ti-coated Si-substrates. NDs were functionalized with mixture of carboxyl and amine groups ND andante or amine ND amine , carboxyl ND vox or hydroxyl groups ND H and drop-casted or spray-coated onto substrate. By utilizing these novel structures we show that (i) the detection limit for dopamine can be improved by two orders of magnitude [from 10µM to 50nM] in comparison to ta-C thin film electrodes and (ii) the coating method significantly affects electrochemical properties of NDs and (iii) the ND coatings selectively promote cell viability. ND andante and ND H showed most promising electrochemical properties. The viability of human mesenchymal stem cells and osteoblastic SaOS-2 cells was increased on all ND surfaces, whereas the viability of mouse neural stem cells and rat neuroblastic cells was improved on ND andante and ND H and reduced on ND amine and ND vox. The viability of C6 cells remained unchanged, indicating that these surfaces will not cause excess gliosis. In summary, we demonstrated here that by using functionalized NDs on ta-C thin films we can significantly improve sensitivity towards dopamine as well as selectively promote cell viability. Thus, these novel carbon nanostructures provide an interesting concept for development of various in vivo targeted sensor solutions. Copyright © 2016 Elsevier B.V. All rights reserved.

Occurrence and distribution of antibiotics in surface water impacted by crab culturing: a case study of Lake Guchenghu, China.

PubMed

Wang, Wenxia; Zhou, Lijun; Gu, Xiaohong; Chen, Huihui; Zeng, Qingfei; Mao, Zhigang

2018-05-30

The objective of this study was to evaluate the occurrence, distribution, potential sources, and ecological risk of antibiotics in aqueous phase of Lake Guchenghu, China. Target antibiotics in surface water of Lake Guchenghu, adjacent streams, and crab ponds were detected seasonally. The results showed that erythromycin-H 2 O (1.60-2450 ng/L), sulfadiazine (ND-654 ng/L), and florfenicol (ND-919 ng/L) were the predominant antibiotics in Lake Guchenghu. The concentrations of antibiotics in Lake Guchenghu Basin showed obvious seasonal variation, with the highest concentration in summer. In general, the concentrations of antibiotics in crab ponds and streams were higher than those in the lake and spatial distributions of antibiotics were affected by pollution sources. The types and origins of antibiotics indicated that wastewater from ponds was the main source of antibiotics in the lake. Risk assessment suggested that as individual compound, erythromycin-H 2 O and clarithromycin posed a high risk to algae while other compounds might pose low or no risk. The mixture of antibiotics may pose a high risk to aquatic organisms in Lake Guchenghu. Overall, our study revealed the occurrence and spatiotemporal variation of antibiotics in Lake Guchenghu, which was related with crab culturing.

Effect of RE (Nd3+, Sm3+) oxide on structural, optical properties of Na2O-Li2O-ZnO-B2O3 glass system

NASA Astrophysics Data System (ADS)

Hivrekar, Mahesh M.; Bhoyar, D. N.; Mande, V. K.; Dhole, V. V.; Solunke, M. B.; Jadhav, K. M.

2018-05-01

Zinc borate glass activated with rare earth oxide (Nd2O3, Sm2O3) of Na2O-Li2O-ZnO-B2O3 quaternary system has been prepared successfully by melt quenching method. The nucleation and growth of RE oxide were controlled temperature range 950-1000° C and rapid cooling at room temperature. The physical, structural and optical properties were characterized by using X-ray diffraction (XRD), SEM, Ultraviolet-visible spectroscopy (UV-Vis). XRD and SEM studies confirmed the amorphous nature, surface morphology of prepared zinc borate glass. The physical parameters like density, molar volume, molar mass of Nd3+, Sm3+ doped borate glass are summarized in the present article. The optical absorption spectra along with tauc's plot are presented. The optical energy band gap increases due to the addition of rare earth oxide confirming the role of network modifier.

Nd2O3-SiO2 nanocomposites: A simple sonochemical preparation, characterization and photocatalytic activity.

PubMed

Zinatloo-Ajabshir, Sahar; Mortazavi-Derazkola, Sobhan; Salavati-Niasari, Masoud

2018-04-01

Nd 2 O 3 -SiO 2 nanocomposites with enhanced photocatalytic activity have been obtained through simple and rapid sonochemical route in presence of putrescine as a new basic agent, for the first time. The influence of the mole ratio of Si:Nd, basic agent and ultrasonic power have been optimized to obtain the best Nd 2 O 3 -SiO 2 nanocomposites on shape, size and photocatalytic activity. The produced Nd 2 O 3 -SiO 2 nanocomposites have been characterized utilizing XRD, EDX, TEM, FT-IR, DRS and FESEM. Application of the as-formed Nd 2 O 3 -SiO 2 nano and bulk structures as photocatalyst with photodegradation of methyl violet contaminant under ultraviolet illumination was compared. Results demonstrated that SiO 2 has remarkable effect on catalytic performance of Nd 2 O 3 photocatalyst for decomposition. By introducing of SiO 2 to Nd 2 O 3 , decomposition efficiency of Nd 2 O 3 toward methyl violet contaminant under ultraviolet illumination was increased. Copyright © 2017 Elsevier B.V. All rights reserved.

The circum-Antarctic sedimentary record; a dowsing rod for Antarctic ice in the Eocene

NASA Astrophysics Data System (ADS)

Scher, H.

2012-12-01

Arguments for short-lived Antarctic glacial events during the Eocene (55-34 Ma) are compelling, however the paleoceanographic proxy records upon which these arguments are based (e.g., benthic δ18O, eustatic sea level, deep sea carbonate deposition) are global signals in which the role of Antarctic ice volume variability is ambiguous. That is to say, the proxy response to ice volume may be masked other processes. As a result broad correlations between proxies for ice volume are lacking during suspected Eocene glacial events. I will present a more direct approach for detecting Antarctic ice sheets in the Eocene; utilizing provenance information derived from the radiogenic isotopic composition of the terrigenous component of marine sediments near Antarctica. The method relies on knowledge that marine sediments represent a mixture derived from different basement terrains with different isotopic fingerprints. A key issue when using sedimentary deposits to characterize continental sediment sources is to deconvolve different sources from the mixed signal of the bulk sample. The pioneering work of Roy et al. (2007) and van de Flierdt et al. (2007) represents a major advance in Antarctic provenance studies. It is now known that the isotopic composition of neodymium (Nd) and hafnium (Hf) in modern circum-Antarctic sediments are distributed in a pattern that mimics the basement age of sediment sources around Antarctica. For this study I selected two Ocean Drilling Program (ODP) sites on southern Kerguelen Plateau (ODP Sites 738 and 748) because of their proximity to Prydz Bay, where Precambrian sediment sources contribute to extremely nonradiogenic isotopic signatures in modern sediments in the Prydz Bay region. New detrital Nd isotope records from these sediment cores reveal an Nd isotope excursion at the Bartonian/Priabonian boundary (ca. 37 Ma) that coincides with a 0.5 ‰ increase in benthic foram δ18O values. Detrital sediment ɛNd values are around -12 in intervals where δ18O values are low and decrease to -15.5 when δ18O values are highest. In contrast there is not a significant change in the ɛNd values of fossil fish teeth across the δ18O excursion at ODP Site 738. Low variability in fossil fish tooth ɛNd values precludes a major reorganization of bottom water circulation that may otherwise have transported terrigenous sediment from distal areas. Thus, the results from this study provide very strong evidence for an increase in the amount of fine-grained terrigenous material that was discharged from the Prydz Bay drainage and/or a change in the sediment source. I argue that these data provide evidence for erosion/weathering of Antarctic basement rocks by small ice sheets that formed in the hinterland of the Prydz Bay drainage. The approach that will be presented holds great promise for identifying short-lived glaciations on Antarctica prior to the major development of ice sheets at the Eocene Oligocene boundary. Understanding the timing, frequency, and duration of these events is paramount to evaluating the processes and feedbacks that resulted in the global transition from greenhouse to icehouse. References: Roy, M., et al. (2007), Chemical Geology, 244, 507-519. van de Flierdt T, Goldstein SL, Hemming SR, et al, Earth and Planetary Science Letters, 2007, 259, Pages:432-441.

Zircon trace element and isotopic (Sr, Nd, Hf, Pb) effects of assimilation-fractional crystallization of pegmatite magma: A case study of the Guangshigou biotite pegmatites from the North Qinling Orogen, central China

NASA Astrophysics Data System (ADS)

Yuan, Feng; Liu, Jia-Jun; Carranza, Emmanuel John M.; Zhang, Shuai; Zhai, De-Gao; Liu, Gang; Wang, Gong-Wen; Zhang, Hong-Yuan; Sha, Ya-Zhou; Yang, Shang-Song

2018-03-01

Evidence for open-system magmatic processes related to wallrock assimilation accompanied by fractional crystallization (AFC) is present in the Guangshigou biotite pegmatites, North Qinling Orogen. The biotite pegmatite-gneiss contacts generally coincide with the greatest enrichment of U and Th. Zircon Usbnd Pb dating constrains the crystallization ages of the biotite pegmatite (rim zone-415 ± 2.6 Ma; internal zone-413.5 ± 2.5 Ma), in line with a pyrite Pbsbnd Pb isochron age (413 ± 22 Ma). Metamict areas in zircon show generally elevated concentrations of trace elements and expulsion of radioactive Pb. Internal zone samples, representing uncontaminated magma, have negative to positive zircon ( 413 Ma) εHf(t) (- 1.53 - + 3.24), low εNd(t) values (- 2.4), and old Hf and Nd model ages (tDM2 = 1.5-1.19 Ga, T2DM = 1.35 Ga, respectively), indicating a dominantly recycled Mesoproterozoic lower crustal material with involvement of some juvenile materials in the source region. The magmatic oxygen fugacity (fO2) and crystallization temperatures ranges from - 24.81 to - 13.34 of log fO2 and 570 °C to 793 °C, respectively. Compared to the internal zone, pegmatite rim samples display a variable and lower εNd(t) values (- 3.9 to - 2.8) and T2DM (1.47-1.37 Ga), but similar Hf isotopic compositions, favouring a three-component isotopic mixing model (recycled Mesoproterozoic lower crust materials, juvenile materials, and host gneiss). Pronounced variations of Ti, Y, U, Th, Hf, and REE concentrations in zircon from grain to grain in individual samples and from area to area within individual grains suggest a fluctuating crystallization environment in hybridized magma from which the rim-hosted zircons crystallized. Variable and high radiogenic Pb ratios of pyrites forming in the hybridized magma were inherited from the matrix. Zircons from both zones exhibit similar Hf isotope patterns, indicating the rim-hosted zircons crystallized during the early stage of hybridization of magma. However, the heterogeneous Nd isotopic composition in individual pegmatites imply an incorporation of wallrock-derived melt with less radiogenic Nd.

Nandrolone decanoate is able to modulate proliferation and adhesion of myoblasts.

PubMed

Oliveira, E N; Fernandes, K P; Silva, C A; Oliveira, T S; Junior, J A; Bussadori, S K; Renno, A C; Mesquita-Ferrari, R A

2014-07-01

The search for a more efficient repair process of muscle injuries has become evident in clinical practice. The aim of the present study was to evaluate the effect of nandrolone decanoate (ND) on the proliferation, adhesion, and expression of myogenic regulatory factors (MRFs) in C2C12 cells.Methods. Cell proliferation and adhesion were assessed using an MTT assay. The expression of MRFs was assessed by real-time PCR.Results. ND applied at 10 or 25 µM concentration induced after 60 min an increase in adhesion, at 5 µM concentration induced after 5 days an increase in cell proliferation, and ND at 50 µM concentration led after 5 days to a decrease in cell proliferation in comparison with other groups. The steroid did not alter the expression of MRFs.Conclusions. The positive effects of ND regarding the proliferation and adhesion of C2C12 cells suggest that this steroid may have positive effects following a muscle injury.

Comparative study of Nd:KGW lasers pumped at 808 nm and 877 nm

NASA Astrophysics Data System (ADS)

Huang, Ke; Ge, Wen-Qi; Zhao, Tian-Zhuo; He, Jian-Guo; Feng, Chen-Yong; Fan, Zhong-Wei

2015-10-01

The laser performance and thermal analysis of Nd:KGW laser continuously pumped by 808 nm and 877 nm are comparatively investigated. Output power of 670 mW and 1587 mW, with nearly TEM00 mode, are achieved respectively at 808 nm pump and 877 nm pump. Meanwhile, a high-power passively Q-switched Nd:KGW/Cr4+:YAG laser pumped at 877 nm is demonstrated. An average output power of 1495 mW is obtained at pump power of 5.22 W while the laser is operating at repetition of 53.17 kHz. We demonstrate that 877 nm diode laser is a more potential pump source for Nd:KGW lasers.

A diode-pumped Nd:YAlO3 dual-wavelength yellow light source

NASA Astrophysics Data System (ADS)

Zhang, Jing; Fu, Xihong; Zhai, Pei; Xia, Jing; Li, Shutao

2013-11-01

We present what is, to the best of our knowledge, the first diode-pumped Nd:YAlO3 (Nd:YAP) continuous-wave (cw) dual-wavelength yellow laser at 593 nm and 598 nm, based on sum-frequency generation between 1064 and 1339 nm in a-axis polarization using LBO crystal and between 1079 and 1341 nm in c-axis polarization using PPKTP crystal, respectively. At an incident pump power of 17.3 W, the maximum output power obtained at 593 nm and 598 nm is 0.18 W and 1.86 W, respectively. The laser experiment shows that Nd:YAP crystal can be used for an efficient diode-pumped dual-wavelength yellow laser system.

Development of all-solid-state coherent 589 nm light source: toward the realization of sodium lidar and laser guide star adaptive optics

NASA Astrophysics Data System (ADS)

Saito, Norihito; Akagawa, Kazuyuki; Kato, Mayumi; Takazawa, Akira; Hayano, Yutaka; Saito, Yoshihiko; Ito, Meguru; Takami, Hideki; Iye, Masanori; Wada, Satoshi

2006-12-01

We report an all-solid-state coherent 589 nm light source in single-pass sum-frequency generation (SFG) with actively mode-locked Nd:YAG lasers for the realization of sodium lidar and laser guide star adaptive optics. The Nd:YAG lasers are constructed as a LD-side-pumped configuration and are operated at 1064 and 1319 nm for 589 nm light generation in SFG. Output powers of 16.5 and 5.3 W at 1064 and 1319 nm are obtained with two pumping chambers. Each chamber consisted of three 80-W-LD arrays. Single transverse mode TEM 00; M2 ~1.1 is achieved with adjustment of cavity length considering thermal lens effect with increase of input LD power. The cavity length is set to approximately 1 m. Accordingly the mode-locked lasers are operated at a repetition rate of approximately 150 MHz. Synchronization of two pulse trains at 1064 and 1319 nm is accomplished by control of phase difference between two radio frequencies input in acousto-optic mode-lockers. Then temporal delay is controlled with a resolution of 37 ps/degree. Pump beams are mixed in periodically poled stoichiometric lithium tantalate (PPSLT) without an antireflection coating. The effective aperture and length of the crystal are 0.5 × 2 mm2 and 15 mm. When input intensity is set at 5.6 MW/cm , an average output power of 4.6 W is obtained at 589.159 nm. Precise tuning to the sodium D II line is accomplished by thermal control of etalons set in the Nd:YAG lasers. The output power at 589.159 nm is stably maintained within +/-1.2% for 8 hours.

Stereological estimation of ovarian oocyte volume, surface area and number: application on mice treated with nandrolone decanoate.

PubMed

Karbalay-Doust, Saied; Noorafshan, Ali

2012-07-05

Changes in the number and size of oocytes can lead to fertilization problems. The present study aimed to evaluate the number, volume, and surface area of oocytes in healthy as well as nandrolone decanoate-treated (ND) mice using stereological methods. Five control mice received vehicle, and five ND-treated mice received ND. Using the 'isotropic Cavalieri' design', the ovary was sectioned. The volume of the ovary (cortex and medulla) was estimated. The oocytes' volume and surface area were estimated using the invariator. The number of the oocytes was estimated using an optical disector. The volumes of the ovary, cortex, and medulla decreased ~50% in the ND-treated mice. The mean number (coefficient of variation) of preantral, antral, and atretic oocytes in the control ovary were 1,690 (0.29), 2,100 (0.52), and 3,900 (0.2), respectively, which decreased ~54%, ~87%, and ~91%, respectively in the ND-treated animals. The mean volume (coefficient of variation) of the preantral, antral, and atretic oocytes were 86,000 (0.27), 110,000 (0.48), and 27,000 (0.33) μm³, respectively. The mean surface area (coefficient of variation) of the three types of oocytes were 9,000 (0.24), 9,900 (0.28), and 4,700 (0.21) μm², respectively. These parameters remained unchanged in the ND-treated mice. ND induces reduction in the number of oocytes, but not in the volume or the surface area.

The effect of B{sub 2}O{sub 3} flux on growth NLBCO superconductor by solid state reaction and wet-mixing methods

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

Suharta, W. G., E-mail: wgsuharta@gmail.com; Wendri, N.; Ratini, N.

The synthesis of B{sub 2}O{sub 3} flux substituted NLBCO superconductor NdBa{sub 1.75}La{sub 0.25}Cu{sub 3}O{sub 7-∂} has been done using solid state reaction and wet-mixing methods in order to obtain homogeneous crystals and single phase. From DTA/TGA characteritations showed the synthesis process by wet-mixing requires a lower temperature than the solid state reaction in growing the superconductor NdBa{sub 1.75}La{sub 0.25}Cu{sub 3}O{sub 7-∂}. Therefore, in this research NdBa{sub 1.75}La{sub 0.25}Cu{sub 3}O{sub 7-∂} sample calcinated at 650°C for wet-mixing method and 820°C for solid state reaction methods. The all samples was sintered at 950°C for ten hours. Crystallinity of the sample was confirmedmore » using X-ray techniques and generally obtained sharp peaks that indicates the sample already well crystallized. Search match analyses for diffraction data gave weight fractions of impurity phase of the solid state reaction method higher than wet-mixing method. In this research showed decreasing the price of the lattice parameter about 1% with the addition of B{sub 2}O{sub 3} flux for the both synthesis process and 2% of wet mixing process for all samples. Characterization using scanning electron microscopy (SEM) showed the distribution of crystal zise for wet-mixing method more homogeneous than solid state reaction method, with he grain size of samples is around 150–250 nm. The results of vibrating sample magnetometer (VSM) showed the paramagnetic properties for all samples.« less

Implications of Nb/U, Th/U and Sm/Nd in plume magmas for the relationship between continental and oceanic crust formation and the development of the depleted mantle

NASA Astrophysics Data System (ADS)

Campbell, Ian H.

2002-05-01

The Nb/U and Th/U of the primitive mantle are 34 and 4.04 respectively, which compare with 9.7 and 3.96 for the continental crust. Extraction of continental crust from the mantle therefore has a profound influence on its Nb/U but little influence on its Th/U. Conversely, extraction of midocean ridge-type basalts lowers the Th/U of the mantle residue but has little influence on its Nb/U. As a consequence, variations in Th/U and Nb/U with Sm/Nd can be used to evaluate the relative importance of continental and basaltic crust extraction in the formation of the depleted (Sm/Nd enriched) mantle reservoir. This study evaluates Nb/U, Th/U, and Sm/Nd variations in suites of komatiites, picrites, and their associated basalts, of various ages, to determine whether basalt and/or continental crust have been extracted from their source region. Emphasis is placed on komatiites and picrites because they formed at high degrees of partial melting and are expected to have Nb/U, Th/U, and Sm/Nd that are essentially the same as the mantle that melted to produce them. The results show that all of the studied suites, with the exception of the Barberton, have had both continental crust and basaltic crust extracted from their mantle source region. The high Sm/Nd of the Gorgona and Munro komatiites require the elevated ratios seen in these suites to be due primarily to extraction of basaltic crust from their source regions, whereas basaltic and continental crust extraction are of subequal importance in the source regions of the Yilgarn and Belingwe komatiites. The Sm/Nd of modern midocean ridge basalts lies above the crustal extraction curve on a plot of Sm/Nd against Nb/U, which requires the upper mantle to have had both basaltic and continental crust extracted from it. It is suggested that the extraction of the basaltic reservoir from the mantle occurs at midocean ridges and that the basaltic crust, together with its complementary depleted mantle residue, is subducted to the core-mantle boundary. When the two components reach thermal equilibrium with their surroundings, the lighter depleted component separates from the denser basaltic component. Both are eventually returned to the upper mantle, but the lighter depleted component has a shorter residence time in the lower mantle than the denser basaltic component. If the difference in the recycling times for the basaltic and depleted components is ˜1.0 to 1.5 Ga, a basaltic reservoir is created in the lower mantle, equivalent to the amount of basalt that is subducted in 1.0 to 1.5 Ga, and that reservoir is isolated from the upper mantle. It is this reservoir that is responsible for the Sm/Nd ratio of the upper mantle lying above the trend predicted by extraction of continental crust on the plot of Sm/Nd against Nb/U.

Variations in the Nd isotope composition of Late Miocene to Early Pliocene glacially derived sediments in Prydz Bay, East Antarctica

NASA Astrophysics Data System (ADS)

Mabson, M.; Pierce, E. L.; Dale, C. L.; Williams, T.; Hemming, S. R.; van de Flierdt, T.; Cook, C.; Goldstein, S. L.

2010-12-01

Michelle Mabson (Howard University), Elizabeth Pierce (Lamont-Doherty Earth Observatory, Columbia University), Cathleen Doherty (Lamont-Doherty Earth Observatory, Columbia University), Trevor Williams (Lamont-Doherty Earth Observatory), Sidney Hemming (Lamont-Doherty Earth Observatory), Tina van de Flierdt (Imperial College London), Carys Cook (Imperial College London), Steve Goldstein (Lamont-Doherty Earth Observatory) Since initiation of major ice sheets on Antarctica at about 34 Ma, Antarctica has been a major player in global climate change. Understanding the response of the East Antarctic Ice Sheet to major climate changes through the Cenozoic has fundamental importance to both Earth Sciences and Society. Previous study of Nd isotope composition of sediments at Ocean Drilling Program (ODP) Site 1166 within Prydz Bay found evidence for variations of the Nd isotope composition between -15 to -30 epsilon units through this pre-glacial to glacial record (van de Flierdt et al., 2008, GRL). The Nd isotope composition of sediments provides an estimate for the average continental crust formation age of the sources. The sources around Prydz Bay have a wide range of formation ages, from Archean to Phanerozoic, so the areas which were being preferentially eroded can be inferred. This study seeks to contribute evidence for the local variations in provenance of sediments by extending the record of Nd isotope variations to ODP Site 739 in Prydz Bay. ODP Site 1165 has an unconformity that spans ~30-3 Ma. This part of the record is much more complete in ODP site 739, located about 200 km from the coast of Prydz Bay, probably more protected from ice stream erosion in the Prydz Channel. Because of its location we can conclude that the sediment deposited into this area is derived from the Lambert Glacier, and thus the variations in epsilon Nd will allow testing whether changes in the extent of this ice stream could lead to variations in the provenance of sediment carried by this ice. Recently Williams et al. (2010, EPSL) published evidence for dramatic changes in the sources of glacially derived sediments at ODP Site 1165, further offshore from Prydz Bay, at 7, 4.8 and 3.5 Ma. Their interpretation was based on the Ar-Ar ages of detrital hornblende grains, but samples taken across the 4.8 Ma event also showed an intriguing variation of the Nd isotope composition. The older part of the event includes a significant fraction of exotic Ar-Ar ages, but with epsilon Nd similar to the background values, while the younger part of the event shows a significant decrease in epsilon Nd but Ar-Ar of local origin. The specific goal of this study is to test the hypothesis that the shift to lower epsilon Nd in the 4.8 Ma ice rafting event is due to dynamical changes in the Prydz Bay sector of the East Antarctic ice sheet. Alternatively, the Lambert glacier may have retreated far enough to allow other sources in this sector to dominate the sediment composition in core 1165.

VizieR Online Data Catalog: ND2 rotational spectrum (Melosso+,

NASA Astrophysics Data System (ADS)

Melosso, M.; Degli Esposti, C.; Dore, L.

2018-01-01

files used with the SPFIT/SPCAT program suite. There are 8 files of supplementary material, including a ReadMe, which was created by the AAS data editors. The text files are as follows: 1_Explan.txt = information on the content of the other files. 2ND2.fit = the output file of the fit of spectroscopic data used in the present study. 3ND2.lin = the corresponding line file. 4ND2.par = the corresponding parameter file. 5ND2.cat = the output file of the prediction made with the parameters determined in this study. 6ND2.var = the corresponding parameter file 7ND2.int = the corresponding intensity file (1 data file).

Passively mode-locked pulse generation in a c-cut Nd:LuVO4 laser at 1086 nm with a semiconductor saturable-absorber mirror

NASA Astrophysics Data System (ADS)

Lin, Ja-Hon; Yang, Pao-Keng; Lin, Wei-Cheng

2012-04-01

We demonstrate a diode-pumped passively mode-locked (ML) c-cut Nd:LuVO4 laser with central wavelength at 1086 nm by shifting the reflectance band of the SESAM into a longer wavelength to result in larger loss around 1068 nm. At 15 W absorbed pump power, the highest output power of the ML pulse was about 2.6 W that corresponded to the 17.3% optical-to-optical conversion efficiency and the slope efficiency of laser was about 22.9%. Using our ML laser as the light source, we have also successfully measured the saturation fluence of the SESAM at 1086 nm.

[Current strategy in PCI for CTO].

PubMed

Asakura, Yasushi

2011-02-01

Recently, CTO PCI has come into wide use all over the world and it has been standardized. The 1st step is an antegrade approach using single wire. The 2nd strategy would be parallel wire technique. And the next would be a retrograde approach. In this method, retrograde wiring with Corsair is done at first. If it is successful, externalization is established using 300 cm wire, and this system is able to provide strong back-up support. If it fails, reverse CART technique is the next step. IVUS guided wiring is a last resort. The 2nd wire is manipulated with IVUS guidance. Now, initial success rate is more than 90% with these methods.

Charactering baseline shift with 4th polynomial function for portable biomedical near-infrared spectroscopy device

NASA Astrophysics Data System (ADS)

Zhao, Ke; Ji, Yaoyao; Pan, Boan; Li, Ting

2018-02-01

The continuous-wave Near-infrared spectroscopy (NIRS) devices have been highlighted for its clinical and health care applications in noninvasive hemodynamic measurements. The baseline shift of the deviation measurement attracts lots of attentions for its clinical importance. Nonetheless current published methods have low reliability or high variability. In this study, we found a perfect polynomial fitting function for baseline removal, using NIRS. Unlike previous studies on baseline correction for near-infrared spectroscopy evaluation of non-hemodynamic particles, we focused on baseline fitting and corresponding correction method for NIRS and found that the polynomial fitting function at 4th order is greater than the function at 2nd order reported in previous research. Through experimental tests of hemodynamic parameters of the solid phantom, we compared the fitting effect between the 4th order polynomial and the 2nd order polynomial, by recording and analyzing the R values and the SSE (the sum of squares due to error) values. The R values of the 4th order polynomial function fitting are all higher than 0.99, which are significantly higher than the corresponding ones of 2nd order, while the SSE values of the 4th order are significantly smaller than the corresponding ones of the 2nd order. By using the high-reliable and low-variable 4th order polynomial fitting function, we are able to remove the baseline online to obtain more accurate NIRS measurements.

Deduction of the chemical state and the electronic structure of Nd{sub 2}Fe{sub 14}B compound from X-ray photoelectron spectroscopy core-level and valence-band spectra

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

Wang, Jing; Liang, Le; Zhang, Lanting, E-mail: lantingzh@sjtu.edu.cn, E-mail: lmsun@sjtu.edu.cn

2014-10-28

Characterization of chemical state and electronic structure of the technologically important Nd{sub 2}Fe{sub 14}B compound is attractive for understanding the physical nature of its excellent magnetic properties. X-ray photoelectron spectroscopy (XPS) study of such rare-earth compound is important and also challenging due to the easy oxidation of surface and small photoelectron cross-sections of rare-earth 4f electrons and B 2p electrons, etc. Here, we reported an investigation based on XPS spectra of Nd{sub 2}Fe{sub 14}B compound as a function of Ar ion sputtering time. The chemical state of Fe and that of B in Nd{sub 2}Fe{sub 14}B compound can be clearlymore » determined to be 0 and −3, respectively. The Nd in Nd{sub 2}Fe{sub 14}B compound is found to have the chemical state of close to +3 instead of +3 as compared with the Nd in Nd{sub 2}O{sub 3}. In addition, by comparing the valence-band spectrum of Nd{sub 2}Fe{sub 14}B compound to that of the pure Fe, the contributions from Nd, Fe, and B to the valence-band structure of Nd{sub 2}Fe{sub 14}B compound is made more clear. The B 2p states and B 2s states are identified to be at ∼11.2 eV and ∼24.6 eV, respectively, which is reported for the first time. The contribution from Nd 4f states can be identified both in XPS core-level spectrum and XPS valence-band spectrum. Although Nd 4f states partially hybridize with Fe 3d states, Nd 4f states are mainly localized in Nd{sub 2}Fe{sub 14}B compound.« less

Effect of nandrolone decanoate on Sjögren's syndrome like disorders in NZB/NZW mice.

PubMed Central

Schot, L P; Verheul, H A; Schuurs, A H

1984-01-01

The effects of 2.5-40 mg/kg nandrolone decanoate (ND) on the development and growth of mononuclear cell infiltrations in the submandibular glands of NZB/W (B/W) mice have been studied using a quantitative histological method. Injections with ND for 9 months, once every 3 weeks, starting at 4 weeks of age, reduced the number and total area of infiltrations in submandibular glands of female and castrated male B/W mice. Since ND has relatively weak virilizing properties, this substance may be useful for the treatment of Sjögren's syndrome in humans. Images Fig. 1 PMID:6467680

Rb-Sr, Sm-Nd and Lu-Hf isotope systematics of the lunar Mg-suite: the age of the lunar crust and its relation to the time of Moon formation.

PubMed

Carlson, Richard W; Borg, Lars E; Gaffney, Amy M; Boyet, Maud

2014-09-13

New Rb-Sr, (146,147)Sm-(142,143)Nd and Lu-Hf isotopic analyses of Mg-suite lunar crustal rocks 67667, 76335, 77215 and 78238, including an internal isochron for norite 77215, were undertaken to better define the time and duration of lunar crust formation and the history of the source materials of the Mg-suite. Isochron ages determined in this study for 77215 are: Rb-Sr=4450±270 Ma, (147)Sm-(143)Nd=4283±23 Ma and Lu-Hf=4421±68 Ma. The data define an initial (146)Sm/(144)Sm ratio of 0.00193±0.00092 corresponding to ages between 4348 and 4413 Ma depending on the half-life and initial abundance used for (146)Sm. The initial Nd and Hf isotopic compositions of all samples indicate a source region with slight enrichment in the incompatible elements in accord with previous suggestions that the Mg-suite crustal rocks contain a component of KREEP. The Sm/Nd-(142)Nd/(144)Nd correlation shown by both ferroan anorthosite and Mg-suite rocks is coincident with the trend defined by mare and KREEP basalts, the slope of which corresponds to ages between 4.35 and 4.45 Ga. These data, along with similar ages for various early Earth differentiation events, are in accord with the model of lunar formation via giant impact into Earth at ca 4.4 Ga. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

T-Check in Technologies for Interoperability: Web Services and Security--Single Sign-On

DTIC Science & Technology

2007-12-01

following tools: • Apache Tomcat 6.0—a Java Servlet container to host the Web services and a simple Web client application [Apache 2007a] • Apache Axis...Eclipse. Eclipse – an open development platform. http://www.eclipse.org/ (2007) [Hunter 2001] Hunter, Jason. Java Servlet Programming, 2nd Edition...Citation SAML 1.1 Java Toolkit SAML Ping Identity’s SAML-1.1 implementation [SourceID 2006] OpenSAML SAML An open source implementation of SAML 1.1

Femtosecond laser inscribed cladding waveguides in Nd:YAG ceramics: fabrication, fluorescence imaging and laser performance.

PubMed

Liu, Hongliang; Jia, Yuechen; Vázquez de Aldana, Javier Rodríguez; Jaque, Daniel; Chen, Feng

2012-08-13

We report on the fabrication of depressed cladding waveguide lasers in Nd:YAG (neodymium doped yttrium aluminum garnet, Nd:Y3Al5O12) ceramics microstructured by femtosecond laser pulses. Full control over the confined light spatial distribution is demonstrated by the fabrication of high contrast waveguides with hexagonal, circular and trapezoidal configurations. The confocal fluorescence measurements of the waveguides reveal that the original luminescence features of Nd3+ ions are well-preserved in the waveguide regions. Under optical pump at 808 nm, cladding waveguides showed continuous wave efficient laser oscillation. The maximum output power obtained at 1064.5 nm is ~181 mW with a slope efficiency as high as 44%, which suggests that the fabricated Nd:YAG ceramic waveguides are promising candidates for efficient integrated laser sources.

Near-infrared photoluminescence in La{sub 0.98}AlO{sub 3}: {sub 0.02}Ln{sup 3+}(Ln = Nd/Yb) for sensitization of c-Si solar cells

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

Sawala, N. S., E-mail: nssawala@gmail.com; Koparkar, K. A.; Omanwar, S. K.

2016-05-06

The host matrix LaAlO{sub 3} was synthesized by conventional solid state reaction method in which the Nd{sup 3+} ions and Yb{sup 3+} ions successfully doped at 2mol% concentrations. The phase purity was confirmed by X ray powder diffraction (XRD) method. The photoluminescence (PL) properties were studied by spectrophotometer in near infra red (NIR) and ultra violet visible (UV-VIS) region. The Nd{sup 3+} ion doped LaAlO{sub 3} converts a visible (VIS) green photon (587 nm) into near infrared (NIR) photon (1070 nm) while Yb{sup 3+} ion doped converts ultra violet (UV) photon (221 nm) into NIR photon (980 nm). The La{sub 0.98}AlO{sub 3}: {sub 0.02}Ln{supmore » 3+}(Ln = Nd / Yb) can be potentiality used for betterment of photovoltaic (PV) technology. This result further indicates its potential application as a luminescence converter layer for enhancing solar cells performance.« less

Ultra-high-precision Nd-isotope measurements of geological materials by MC-ICPMS

PubMed Central

Saji, Nikitha Susan; Wielandt, Daniel; Paton, Chad; Bizzarro, Martin

2016-01-01

We report novel techniques allowing the measurement of Nd-isotope ratios with unprecedented accuracy and precision by multi-collector inductively coupled plasma mass spectrometry. Using the new protocol, we have measured the Nd-isotopic composition of rock and synthetic Nd standards as well as that of the Allende carbonaceous chondrite. Analyses of BCR-2, BHVO-2 and GSP-2 rock standards yield mass-independent compositions identical to the JNdi-1 Nd-reference standard, with an external reproducibility of 2.4, 1.6, 1.6 and 3.5 ppm respectively, on μ142Nd, μ145Nd, μ146Nd and μ150Nd (μ representing the ppm-deviation of the ratios from JNdi-1) using 148Nd/144Nd for internal normalization. This represents an improvement in precision by a factor of 2, 7 and 9 respectively for μ142Nd, μ145Nd and μ150Nd. Near-quantitative recovery from purification chemistry and sample-standard bracketing allow for the determination of mass-dependent Nd-isotopic composition of samples. Synthetic standards, namely La Jolla and AMES, record mass-dependent variability of up to 1.2 ε per atomic mass unit and mass-independent compositions resolvable by up to 3 ppm for μ142Nd and 8 ppm for μ150Nd, relative to JNdi-1. The mass-independent compositions are consistent with equilibrium mass fractionation during purification. The terrestrial rock standards define a uniform stable ε145Nd of −0.24 ± 0.19 (2SD) relative to JNdi-1, indistinguishable from the mean Allende ε145Nd of −0.19 ± 0.09. We consider this value to represent the mass-dependent Nd-isotope composition of Bulk Silicate Earth (BSE). The modest mass-dependent fractionation of JNdi-1 relative to BSE results in potential effects on mass-independent composition that cannot be resolved within the reproducibility of our analyses when correcting for natural and instrumental mass fractionation by kinetic law, making it a suitable reference standard for analysis of unknowns. Analysis of Allende (CV3) carbonaceous chondrite returns an average μ142Nd deficit of −30.1 ± 3.7 ppm in agreement with previous studies. The apparent deficit is, however, lowered to −23.8 ± 4.0 ppm while normalizing to 148Nd/144Nd instead of 146Nd/144Nd. We interpret this as the effect of a possible nucleosynthetic anomaly of −6.3 ± 0.5 ppm in μ146Nd. As 142Nd and 146Nd are both s-process-dominated nuclides, this hints at the possibility that terrestrial μ142Nd excess may not reflect 146Sm decay as widely accepted. PMID:27429505

Rhyacian A-type tholeiitic granites in southern Brazil: Geochemistry, U-Pb zircon ages and Nd model ages

NASA Astrophysics Data System (ADS)

Mesquita, Maria José; Bitencourt, Maria de Fátima; Nardi, Lauro Stoll; Picanço, Jefferson; Chemale, Farid, Jr.; Pimenta, Vanessa de Almeida

2017-04-01

In the southern South American platform, 2.5 to 2.0 Ga terranes, probably related to the Atlantica supercontinent, occur mainly as minor reworked inliers within Neoproterozoic, Brasiliano/Pan-African orogenic belts, as the Ribeira Belt in southern Brazil. The dispersion of such fragments has generated uncertainties about their geotectonic reconstruction, and their study has been supported mainly by elemental and isotope geochemistry. The southern Ribeira Belt lies between the Paranapanema and Luiz Alves cratons and contains reworked Neoarquean and Paleoproterozoic terranes which outcrop as basement nuclei in supracrustal sequences, as the Setuva Complex. The Água Comprida Suite, situated in the northern part of the Setuva Complex, consists of Amphibole-Biotite Syenogranite (ABS), Porphyritic Biotite Syenogranite (PBS), and Equigranular Biotite Syenogranite (EBS). All granites are foliated and intensively deformed. The oldest foliation (Sn) is marked by augen feldspars set in a recrystallized matrix, followed by a crenulation cleavage (Sn + 1) which evolves to discrete shear zones. ABS is a metaluminous, reduced A-type granite with FeOt / (FeOt + MgO) > 0.9, with high HFSE and REE contents, corresponding to magmas related to continental medium to high-K tholeiitic series. PBS and specially EBS are highly differentiated, metaluminous to peraluminous (EBS), oxidized granites. The increase of Al2O3 and Rb, and decrease of HFS and RE elements relative to ABS indicate their evolution from tholeiitic magmas. The Água Comprida Suite granites are cogenetic rocks evolved from a within-plate mantle source, marked by high Nb, Ta, and Y. The influence of previously metasomatised mantle sources is evidenced by negative Nb, Ti, and P anomalies. The age of ABS is 2187 ± 26 Ma, and that of PBS is between 2180 ± 13 to 2186 ± 22 Ma. The Nd model age of 2.4 Ga, and εNd(2.18 Ga) between - 0.23 and - 0.27 support the interpretation of ABS being formed from juvenile material with a minor crustal component. The deviation of εNd(2.18 Ga) for PBS and EBS (- 0.69 to - 2.65), plus the higher Nd model ages (2.4 to 2.5 Ga) suggest crustal contamination. A post-collisional environment for the interaction of the mafic tholeiitic and felsic crustal magmas is suggested for the formation of the Água Comprida Suite, based mainly on geochemical features of these magmas. Post-collisional environments are still not described in the Rhyacian orogenies of southern Brazil, and this proposition may be an important contribution for the study of the final period of amalgamation of the Paleoproterozoic supercontinent in southern South America.

Cluster self-organization of TR-containing germanate systems: Suprapolyhedral precursors and self-assembly of the crystal structures of the LiNdGeO{sub 4} and CeGeO{sub 4} compounds

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

Ilyushin, G. D., E-mail: ilyushin@nc.cryst.ras.ru; Dem'yanets, L. N.

2007-07-15

A combinatorial-topological analysis of the orthogermanates LiNdGeO{sub 4} (space group Pbcn) and CeGeO{sub 4} (space group I 4{sub 1}/a, the scheelite structure type), which have MT frameworks composed of polyhedral structural units in the form of M dodecahedra (NdO{sub 8} and CeO{sub 8}) and T tetrahedra (GeO{sub 4}), is performed using the method of coordination sequences with the TOPOS program package. It is established that the structures of both orthogermanates are characterized by equivalent crystal-forming nets 4444. The cluster precursors of the M{sub 2}T{sub 2} cyclic type are identified by the method of two-color decomposition. The local symmetry of four-polyhedralmore » clusters corresponds to the point group 2. In the precursor of the LiNdGeO{sub 4} orthogermanate, the Li atom is located above the M{sub 2}T{sub 2} ring. The number of Li-O bonds in this precursor is 4. The cluster precursors M{sub 2}T{sub 2} and LiM{sub 2}T{sub 2} are responsible for the formation of crystal-forming clusters of a higher level according to the mechanism of matrix self-assembly. The coordination numbers of the cluster precursors in two-dimensional nets for these structures are found to be equal to 4. The equivalent bilayer TR,Ge stacks that consist of eight cluster precursors are revealed in the structures under investigation. It is demonstrated that there exist three types of translational interlayer arrangements of cluster precursors upon the formation of macrostructures of the orthogermanates.« less