Science.gov

Sample records for neodymium silicates

  1. Extruded channel waveguides in a neodymium-doped lead-silicate glass for integrated optic applications

    NASA Astrophysics Data System (ADS)

    Mairaj, Arshad K.; Feng, Xian; Hewak, Daniel W.

    2003-10-01

    We report on the development of channel waveguides in a lead-silicate glass through the extrusion technique. An extruded glass slab with four imbedded fibers each with core size of 8 by 2.5 μm in the horizontal and vertical directions was manufactured. These neodymium-doped channel waveguides were in single-mode operation at 808 nm and had attenuation of 0.1 dB cm-1 at 1.06 μm. The measured 4F3/2 lifetime of 488 μs and emission cross section of 2.5×10-20 cm2 were in good agreement with reported values. The integration of multiple glass variants into a single compact platform is presented as a manufacturing route for complex integrated optical waveguides.

  2. NEW ACTIVE MEDIA AND ELEMENTS OF LASER SYSTEMS: Influence of short-lived color centers on the lifetime of a metastable level of neodymium in silicate glasses

    NASA Astrophysics Data System (ADS)

    Dzhibladze, M. I.; Lazarev, L. E.

    1987-11-01

    It was found that the short-lived color centers formed in neodymium-activated silicate glasses under the action of the violet part of the pump spectrum increased the lifetime of a neodymium metastable level by more than an order of magnitude in needle-shaped waveguide lasers. The highly efficient suppression of superradiance and a strong increase in the gain of the active element were due to stimulated decay of the color centers accompanying absorption of photons emitted by the neodymium.

  3. Color tuning in neodymium doped dicalcium silicate nanostructures prepared via ultrasound method

    NASA Astrophysics Data System (ADS)

    Venkataravanappa, M.; Nagabhushana, H.; Basavaraj, R. B.; Venkatachalaiah, K. N.; Prasad, B. Daruka

    2017-05-01

    Blue light emitting neodymium (Nd) doped dicalcium (Ca2SiO4) silicate nanostructures were prepared for the first time via ultrasound assisted sonochemical synthesis route using cetyltrimethylammonium bromide (CTAB) surfactant. The obtained final product was well characterized. The powder X-ray diffraction (PXRD) profiles confirmed that product was highly crystalline in nature with monoclinic phase. Influence of various reaction parameters such as, the effect of sonication time, concentration of the surfactant and pH of the precursor solution on the morphology was studied in detail. Diffuse reflectance spectroscopy (DRS) was studied to evaluate the band gap energy of the products and the values were found in the range of 5.78 - 6.17 eV. The particle size was estimated by transmission electron microscope (TEM) and it was found in the range of 20-30 nm. Photoluminescence (PL) properties were studied in detail by recording emission spectra of all the Nd doped dicalcium silicate nanostructures at an excitation wavelength of 380 nm. The emission peaks were observed at 469, 520, 545 and 627 nm which corresponds to Nd3+ ion transitions. The 7 mol% Nd3+ doped Ca2SiO4 nanostructures showed maximum intensity. Further photometric measurements were done by evaluating, Commission International De I-Eclairage (CIE) and correlated color temperature (CCT). From CIE it was observed that the color coordinates lies in blue-green region, which slightly shifts to green as the Nd3+ concentration increases. The color purity and quantum efficiency were also estimated and the results indicate that the nanophosphor obtained in this route can be used in preparing light emitting diodes with a blue-green emission as prominent color.

  4. Large-mode-area single-mode-output Neodymium-doped silicate glass all-solid photonic crystal fiber

    PubMed Central

    Li, Wentao; Chen, Danping; Qinling, Zhou; Hu, Lili

    2015-01-01

    We have demonstrated a 45 μm core diameter Neodymium-doped all-solid silicate glass photonic crystal fiber laser with a single mode laser output. The structure parameters and modes information of the fiber are both demonstrated by theoretical calculations using Finite Difference Time Domain (FDTD) method and experimental measurements. Maximum 0.8 W output power limited by launched pump power has been generated in 1064 nm with laser beam quality factor M2 1.18. PMID:26205850

  5. Large-mode-area single-mode-output Neodymium-doped silicate glass all-solid photonic crystal fiber.

    PubMed

    Li, Wentao; Chen, Danping; Qinling, Zhou; Hu, Lili

    2015-07-24

    We have demonstrated a 45 μm core diameter Neodymium-doped all-solid silicate glass photonic crystal fiber laser with a single mode laser output. The structure parameters and modes information of the fiber are both demonstrated by theoretical calculations using Finite Difference Time Domain (FDTD) method and experimental measurements. Maximum 0.8 W output power limited by launched pump power has been generated in 1064 nm with laser beam quality factor M(2) 1.18.

  6. Post-eruptive alteration of silicic ignimbrites and lavas, Gran Canaria, Canary Islands - Strontium, neodymium, lead, and oxygen isotopic evidence

    NASA Technical Reports Server (NTRS)

    Cousens, Brian L.; Spera, Frank J.; Dobson, Patrick F.

    1993-01-01

    The isotopic composition of lavas from oceanic islands provides important information about the composition and evolution of the earth's mantle. Isotopic analyses of Miocene comenditic, pantelleritic, and trachyphonolitic ignimbrites and lavas from the Canary islands were performed. Results provide evidence for posteruptive mobility of Rb and Sr during low temperature postemplacement interaction with circulating ground water. Calculated Sr isotope ratios define a magmatic trend in the stratigraph section. 87Sr/86Sr ratios in hydrated vitrophyte and devitrified matrix separates indicate significant posteruptive interaction with meteoric water starting soon after deposition. This process extends patchily through the entire pyroclastic flow and may be ongoing. 87Sr/86Sr ratios determined by whole rock analysis of silicic rocks from oceanic islands are suspect and should not be incorporated into mantle tracer studies. Anorthoclase phenocrysts are resistant to these processes and may produce useful data.

  7. Post-eruptive alteration of silicic ignimbrites and lavas, Gran Canaria, Canary Islands: Strontium, neodymium, lead, and oxygen isotopic evidence

    SciTech Connect

    Cousens, B.L. ); Spera, F.J. ); Dobson, P.F. )

    1993-02-01

    Isotopic analyses of Miocene comenditic, pantelleritic, and trachyphonolitic ignimbrites and lavas from Gran Canaria, Canary Islands, provide evidence for posteruptive mobility of Rb, Sr, and O. Calculated initial [sup 87]Sr/[sup 86]Sr ratios in whole-rock samples from basaltic lavas and feldspar mineral separates from ignimbrites define a magmatic trend in the stratigraphic section, from ratios of 0.70340 at the base of the Mogan Formation to 0.70305 in the lower Fataga Formation. However, calculated apparent initial [sup 87]Sr/[sup 86]Sr ratios in hydrated vitrophyre and devitrified matrix separates range from 0.7035 to 0.7090. [delta][sup 18]O ratios in basalts and feldspars vary little, from +5.7 to +6.1, yet range from +6.5 to +15.0 in the ignimbrite matrices. In contrast to the Sr and O isotope ratios, Pb and Nd isotope ratios are identical within analytical error in feldspars and their silicic ignimbrite matrices. Sequential leaching experiments and the oxygen data suggest that low-temperature, posteruptive interaction with meteoric water, perhaps containing a small seawater component, has modified Rb and Sr concentrations in the matrices, such that calculated apparent initial [sup 87]Sr/[sup 86]Sr ratios are not those of the magmas when they were erupted. Mobilization of Rb and Sr must occur significantly after eurption. Nd and Pb isotope systems appear to be unaffected by this process. Therefore, [sup 87]Sr/[sup 86]Sr ratios determined by whole rock analysis of silicic rocks from hotspot-type oceanic islands are suspect and should not be incorporated into mantle tracer studies, although analysis of phenocrysts may produce useful data. 40 refs., 5 figs., 3 tabs.

  8. Neodymium Magnets.

    ERIC Educational Resources Information Center

    Wida, Sam

    1992-01-01

    Uses extremely strong neodymium magnets to demonstrate several principles of physics including electromagnetic induction, Lenz's Law, domain theory, demagnetization, the Curie point, and magnetic flux lines. (MDH)

  9. Neodymium Magnets.

    ERIC Educational Resources Information Center

    Wida, Sam

    1992-01-01

    Uses extremely strong neodymium magnets to demonstrate several principles of physics including electromagnetic induction, Lenz's Law, domain theory, demagnetization, the Curie point, and magnetic flux lines. (MDH)

  10. Metals Fact Sheet: Neodymium

    SciTech Connect

    1992-11-01

    Neodymium was discovered in 1898 when it was separated from {open_quotes}dydimium,{close_quotes} a praseodymium-neodymium compound that was thought to be only one element. {open_quotes}Neodymium{close_quotes} is derived from the Greek words {open_quotes}neos{close_quotes} and {open_quotes}didymos,{close_quotes} which translates to {open_quotes}new twin.{close_quotes} This article discusses sources and applications of the element, and reviews world reserves and demands. Price trends in the commodity are also noted.

  11. A 6-GW NEODYMIUM GLASS LASER,

    DTIC Science & Technology

    A 6-GW neodymium glass laser with a simple phototropic Q-switch is described. The laser consists of three cylindrical rods in series, each 250 mm...operation (50-80 microsec. repetition frequency), the total output was 200 j. The use of a phototropic liquid switch and large-diameter neodymium glass

  12. Q-Switching in a Neodymium Laser

    ERIC Educational Resources Information Center

    Holgado, Warein; Sola, Inigo J.; Jarque, Enrique Conejero; Jarabo, Sebastian; Roso, Luis

    2012-01-01

    We present a laboratory experiment for advanced undergraduate or graduate laser-related classes to study the performance of a neodymium laser. In the experiment, the student has to build the neodymium laser using an open cavity. After that, the cavity losses are modulated with an optical chopper located inside, so the Q-switching regime is…

  13. Q-Switching in a Neodymium Laser

    ERIC Educational Resources Information Center

    Holgado, Warein; Sola, Inigo J.; Jarque, Enrique Conejero; Jarabo, Sebastian; Roso, Luis

    2012-01-01

    We present a laboratory experiment for advanced undergraduate or graduate laser-related classes to study the performance of a neodymium laser. In the experiment, the student has to build the neodymium laser using an open cavity. After that, the cavity losses are modulated with an optical chopper located inside, so the Q-switching regime is…

  14. Neodymium neutron cross section measurements.

    PubMed

    Barry, D P; Trbovich, M J; Danon, Y; Block, R C; Slovacek, R E; Leinweber, G; Burke, J A; Drindak, N J

    2005-01-01

    Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Institute LINAC using metallic neodymium samples. The capture measurements were made at the 25-m-long flight station with a 16-segment NaI(Tl) multiplicity detector, and the transmission measurements were performed at 15 and 25 m flight stations with a 6Li glass scintillation detector. After the data were collected and reduced, resonance parameters were determined by simultaneously fitting the transmission and capture data with the multilevel R-matrix Bayesian code SAMMY. The resonance parameters for all naturally occurring neodymium isotopes lie within the energy range of 1.0-500 eV. The resulting resonance parameters were used to calculate the capture resonance integral with this energy region and were compared to calculations obtained when using the resonance parameters from ENDF-B/VI. The RPI parameters gave a resonance integral value of 32 +/- 0.5 b that is approximately 7% lower than that obtained with the ENDF-B/VI parameters. The current measurements significantly reduce the statistical uncertainties on the resonance parameters when compared with previously published parameters.

  15. Electrolysis of neodymium oxide. Final report for the period August 19, 1991 through February 28, 1997

    SciTech Connect

    Keller, R.; Larimer, K.T.

    1997-05-01

    The objective of this research was to develop an electrolytic process for the continuous and economic production of neodymium alloys from neodymium oxide. The electrolysis of neodymium oxide continued to show promise for implementation as a low-cost process to produce high- quality neodymium or neodymium-iron alloy.

  16. Radio-Purification of Neodymium Chloride

    SciTech Connect

    Hans, S.; Yeh, M.; Cumming, J. B.; Hahn, R. L.

    2011-04-27

    Organometallic liquid scintillator becomes one of the man detection mediums for neutrino experiment. Liquid-liquid extraction is the method of choice for loading metallic ions of interest into the organic solvents at BNL. High purity of all starting materials is essential for the optimization of synthesis. A newly developed 'self-scavenging' technique was applied to purify undesired radioisotopes from the starting metal compound and found to effectively remove thorium and such containments from the neodymium chloride for SNO+.

  17. Neodymium and strontium isotopic constraints on soil sources in Barbados, West Indies

    NASA Astrophysics Data System (ADS)

    Borg, Lars E.; Banner, Jay L.

    1996-11-01

    Neodymium and strontium isotopic compositions and Sm/Nd ratios are used to constrain the sources of silicate-rich soils developed on uplifted Pleistocene coral-reef limestones on Barbados, West Indies. The geographic and geologic setting of Barbados facilitates the application of these tracers to the evaluation of the following soil sources: (1) Pleistocene reef limestone regolith, (2) Tertiary carbonate rocks, sandstones, and mudstones that are exposed in northeastern Barbados, (3) volcanic ash erupted from the Lesser Antilles arc, (4) Saharan dust transported by trade winds, and (5) fertilizer. The soils have ɛNd values that range from -6.6 to -1.9, 87Sr /86Sr values of 0.70890 to 0.71067, and Sm/Nd ratios of 0.223-0.260. The Pleistocene limestone component is the most significant source of Sr in the soils and a negligible source of Nd. Comparison of Sm and Nd concentrations and neodymium isotopic compositions of soil samples that are weathered to varying extents indicates that Sm and Nd are relatively unfractionated and retained in the soils during weathering. ɛNd and Sm/Nd variations in the soils, therefore, primarily reflect the compositions and proportions of the silicate sources. Mass balance calculations based on SmNd systematics require that the silicate soil components contain between 30-85% volcanic ash, with the remaining silicate fraction comprised of old, continentally-derived sediment. In contrast to Sm and Nd, Sr is mobilized and removed from the soils during weathering. Strontium from volcanic and carbonate sources is preferentially removed relative to continental silicate sources. The strontium isotopic compositions of the soils, therefore, reflect the combined effects of the degree of weathering and the compositions and proportions of the soil sources. Mass balance calculations indicate that at least 35-60% of the initial Sr in the soils has been removed by weathering. These results illustrate (1) the utility of radiogenic isotopes in

  18. Neodymium-142 evidence for Hadean mafic crust.

    PubMed

    O'Neil, Jonathan; Carlson, Richard W; Francis, Don; Stevenson, Ross K

    2008-09-26

    Neodymium-142 data for rocks from the Nuvvuagittuq greenstone belt in northern Quebec, Canada, show that some rock types have lower 142Nd/144Nd ratios than the terrestrial standard (epsilon142Nd = -0.07 to -0.15). Within a mafic amphibolite unit, 142Nd/144Nd ratios correlate positively with Sm/Nd ratios and produce a 146Sm-142Nd isochron with an age of 4280(-81)(+53) million years. These rocks thus sample incompatible-element-enriched material formed shortly after Earth formation and may represent the oldest preserved crustal section on Earth.

  19. Neodymium nanoparticles: biosynthesis and structural analysis.

    PubMed

    Ascencio, J A; Canizal, G; Medina-Flores, A; Bejar, L; Tavera, L; Matamoros, H; Liu, H B

    2006-04-01

    Small metallic nanoparticles of neodymium are obtained by a facile route based on the biosynthesis and the pH conditions that demonstrate the possibility of obtaining particles of 1-8 nm. The size is controlled by synthesis conditions. Smaller clusters were obtained with pH = 5, while for pH = 10 evidences of nanorods productions are found and this opens the perspective to use this rare-earth element for zero and one dimensional based applications. Using transmission electron microscopy techniques, the size distribution and structure are studied. Density functional theory-based calculations allow the determination of the lowest energy configuration, which is based on the hexagonal bulk symmetry. Theoretical models are used to simulate the high resolution transmission electron microscopy to identify the experimental image, determining that the synthesized nanoparticles reach the lowest energy hexagonal configurations.

  20. Neodymium YAG Lasers. Citations from the NTIS data base

    NASA Astrophysics Data System (ADS)

    Carrigan, B.

    1980-07-01

    Federally funded research reports on lasing of neodymium doped yttrium aluminum garnet are cited. Studies on design, fabrication, quantum efficiency, light pulses, stabilization, and testing are covered. Optical pumping, mode locking, frequency conversion, and modulation of these lasers are discussed. Laser applications such as optical communication, range finding, and tracking are included. Safety hazards and radiation damage related to neodymium YAG lasers are also covered. This updated bibliography contains 181 citations, 15 of which are new entries to the previous edition.

  1. Selective recognition of neodymium (III) using ion imprinted polymer particles.

    PubMed

    Krishna, Paramesamangalam Gopi; Gladis, Joseph Mary; Rao, Talasila Prasada; Naidu, Gurijala Ramakrishna

    2005-01-01

    Neodymium (III) ion-imprinted polymer (IIP) materials were prepared by the copolymerization of neodymium (III)-5,7-dichloroquinoline-8-ol-4-vinylpyridine ternary complex with styrene(monomer), divinyl benzene (crosslinking monomer) in the presence of 2,2'-azobisisobutyronitrile (initiator). The synthesis was carried out in 2-methoxy ethanol medium (porogen) and the resultant material was filtered, washed, dried and powdered to form unleached IIP particles. The imprint ion was removed by stirring the above particles with 50% (v/v) HCl for 6 h to obtain leached IIP particles with cavities in the polymer particles. Control polymer (CP) particles were similarly prepared without imprint ion, i.e. neodymium (III). CP, unleached and leached IIP particles were characterized by TLC, IR, microanalysis, XRD and UV-visible spectrophotometric studies. The preconcentration of 5-150 microg of neodymium (III) ions present in 500 ml of solution was possible with as little as 40 mg of neodymium (III) IIP particles in the pH range 7.5-8.0 with a detection limit of 50 ng/l. Five replicate determinations of 25 microg of neodymium (III) present in 500 ml of solution gave a mean absorbance of 0.120 with a relative standard deviation of 2.65%. The imprinting effect of IIP particles was noticed in all preconcentration and selectivity studies when compared with CP particles. Furthermore, the selectivity coefficients of neodymium (III) IIP particles were much higher compared with the reported separation factors for the best liquid-liquid extractants, viz. di-2-ethylhexyl phosphoric acid and 2-ethylhexyl-ethylhexyl phosphonate. Kinetic and isotherm studies during rebinding of neodymium (III) onto IIP particles were also carried out.

  2. Boundary processes traced by neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Jeandel, C.; Lacan, F.

    2003-04-01

    Continental margins have been identified as preferential sites for removing of reactive elements from the ocean, on the base of U-series measurements (more specifically 231Pa/230Th). This process is called boundary scavenging (Bacon, 1988). Five years of neodymium isotopes data in water masses along the ocean margins (Indonesia, Papua New Guinea, Greenland-Scotland ridge and Labrador Sea) suggests that Nd is transferred from the sediments to the ocean but the reverse also occurs via the so-called boundary scavenging. These processes are only detectable by isotopic ratio measurements because they affect the isotopic signature of the water mass coming in contact with the margin, without changing its concentration. They can involve much higher fluxes than net input processes: for example, the modification of the AAIW signature along the Papua New Guinea slope involves exchange processes only (Lacan and Jeandel, 2001). Since we suspect that such processes not only affect the Nd oceanic chemistry but also the chemical fate of other reactive elements in the ocean, we suggest that the concept of boundary scavenging should be extended to "boundary exchange".

  3. Nonaqueous Synthesis of Gadolinium and Neodymium Nanoparticles

    NASA Astrophysics Data System (ADS)

    Fukuda, R.; Castro, M.; Ho, P.-C.; Attar, S.; Golden, M.; Margosan, D.

    2014-03-01

    Nanoparticles are of great interest due to their magnetic properties, such as superparamagnetism, that are not exhibited by their bulk counterparts. Gd and Nd are being tested by applying the reverse micelle method. The reverse micelle method consists of using a surfactant with a large nonpolar solvent to polar solvent ratio to form spherical cages that control the size of the products. Many studies involving the reverse micelle method employ water as the polar solvent. Since Gd and Nd are highly reactive to water, methanol is used as a replacement with hexane or heptane as the nonpolar solvent. Gadolinium chloride or neodymium nitrate are reduced using sodium borohydride after the reverse micelles encapsulate the rare earth compound. Scanning electron microscopy (SEM) and light microscopy show small, spherical clusters with diameters in the micron range. Higher magnification of the SEM melted the clusters, even after cooling the sample to 87 K. The sample was coated with Pt to prevent melting. Energy dispersive x-ray measurements were conducted to find the chemical composition of the clusters, but the sample signals were too small to make a conclusion. Future growths will use the surfactant DDAB instead of AOT since DDAB is more stable when examined with SEM. Research at California State University-Fresno is supported by NSF DMR-1104544.

  4. Samarium-neodymium direct dating of fluorite mineralization.

    PubMed

    Chesley, J T; Halliday, A N; Scrivener, R C

    1991-05-17

    The direct dating of many styles of hydrothermal mineralization has proved difficult, limiting understanding of the geological processes that lead to crustal fluid flow and the formation of major ore deposits. The hydrothermal mineral fluorite (CaF(2)) displays large variations in rare earth element (REE) abundance and samarium/neodymium ratios within a single vein. Samarium-neodymium dating of fluorite from the classic granite-hosted tin deposits of southwest England demonstrates its use as a precise chronometer of mineralization. The concentrations of light rare earth elements (LREEs) in the fluorites are highly variable and suggest the coeval precipitation of an LREE-rich phase as the most likely cause of the extreme variation in samarium/neodymium ratios.

  5. Neodymium-YAG transscleral cyclophotocoagulation. The role of pigmentation

    SciTech Connect

    Cantor, L.B.; Nichols, D.A.; Katz, L.J.; Moster, M.R.; Poryzees, E.; Shields, J.A.; Spaeth, G.L. )

    1989-08-01

    Using a rabbit model we investigated the role of pigmentation of the ciliary body in obtaining ciliodestruction by neodymium-YAG transscleral cyclophotocoagulation. There was marked destruction of the ciliary body in pigmented rabbit eyes, but no histologic effect was observed in albino rabbit eyes. These findings suggest that pigmentation of the ciliary body is important for obtaining the desired response from neodymium-YAG transscleral cyclophotocoagulation in rabbit eyes by our technique. Further study is necessary to define the role of pigmentation in human eyes in this treatment modality.

  6. New high-strength neodymium phosphate laser glass

    SciTech Connect

    Galagan, B I; Glushchenko, I N; Denker, B I; Kalachev, Yu L; Mikhailov, Viktor A; Sverchkov, S E; Shcherbakov, Ivan A; Kuleshov, N V

    2009-12-31

    A high-strength neodymium laser glass (SNLG) based on an alumoborophosphate composition is developed and synthesised; its physicochemical, spectral, luminescent, and lasing characteristics are studied. It is found that the chemical stability and thermal resistance of the new glass are considerably higher than the corresponding characteristics of known neodymium-doped phosphate laser glasses. Investigations of lasing upon longitudinal diode pumping showed that, due to the higher thermal resistance, the new glass allows one to obtain output powers twice as high as those of industrial GLS22 glass. (active media)

  7. Recycling potential of neodymium: the case of computer hard disk drives.

    PubMed

    Sprecher, Benjamin; Kleijn, Rene; Kramer, Gert Jan

    2014-08-19

    Neodymium, one of the more critically scarce rare earth metals, is often used in sustainable technologies. In this study, we investigate the potential contribution of neodymium recycling to reducing scarcity in supply, with a case study on computer hard disk drives (HDDs). We first review the literature on neodymium production and recycling potential. From this review, we find that recycling of computer HDDs is currently the most feasible pathway toward large-scale recycling of neodymium, even though HDDs do not represent the largest application of neodymium. We then use a combination of dynamic modeling and empirical experiments to conclude that within the application of NdFeB magnets for HDDs, the potential for loop-closing is significant: up to 57% in 2017. However, compared to the total NdFeB production capacity, the recovery potential from HDDs is relatively small (in the 1-3% range). The distributed nature of neodymium poses a significant challenge for recycling of neodymium.

  8. Efficient wide-aperture neodymium glass rod amplifiers

    SciTech Connect

    Potemkin, A K; Zhurin, K A; Kirsanov, A V; Kopelovich, E A; Kuznetsov, M V; Kuz'min, A A; Flat, F A; Khazanov, Efim A; Shaikin, A A

    2011-06-30

    Amplifiers based on neodymium phosphate glass rods 60 - 100 mm in diameter are experimentally studied. The amplifiers are pumped by INP-16/250 tubular flash lamps placed in a universal pump cavity with a two-section mirror reflector. A compact high-voltage capacitive energy storage with a preionisation circuit was developed to supply the lamps. (lasers)

  9. Purification of cerium, neodymium and gadolinium for low background experiments

    NASA Astrophysics Data System (ADS)

    Boiko, R. S.; Barabash, A. S.; Belli, P.; Bernabei, R.; Cappella, F.; Cerulli, R.; Danevich, F. A.; Incicchitti, A.; Laubenstein, M.; Mokina, V. M.; Nisi, S.; Poda, D. V.; Polischuk, O. G.; Tretyak, V. I.

    2014-01-01

    Cerium, neodymium and gadolinium contain double beta active isotopes. The most interesting are 150Nd and 160Gd (promising for 0ν2β search), 136Ce (2β+ candidate with one of the highest Q2β). The main problem of compounds containing lanthanide elements is their high radioactive contamination by uranium, radium, actinium and thorium. The new generation 2β experiments require development of methods for a deep purification of lanthanides from the radioactive elements. A combination of physical and chemical methods was applied to purify cerium, neodymium and gadolinium. Liquid-liquid extraction technique was used to remove traces of Th and U from neodymium, gadolinium and for purification of cerium from Th, U, Ra and K. Co-precipitation and recrystallization methods were utilized for further reduction of the impurities. The radioactive contamination of the samples before and after the purification was tested by using ultra-low-background HPGe gamma spectrometry. As a result of the purification procedure the radioactive contamination of gadolinium oxide (a similar purification efficiency was reached also with cerium and neodymium oxides) was decreased from 0.12 Bq/kg to 0.007 Bq/kg in 228Th, from 0.04 Bq/kg to <0.006 Bq/kg in 226Ra, and from 0.9 Bq/kg to 0.04 Bq/kg in 40K. The purification methods are much less efficient for chemically very similar radioactive elements like actinium, lanthanum and lutetium.

  10. Materials flow analysis of neodymium, status of rare earth metal in the Republic of Korea.

    PubMed

    Swain, Basudev; Kang, Leeseung; Mishra, Chinmayee; Ahn, JoongWoo; Hong, Hyun Seon

    2015-11-01

    Materials flow analysis of neodymium, status of rare earth elements (REEs) in the Republic of Korea has been investigated. Information from various resources like the Korean Ministry of Environment, Korea international trade association, United Nations Commodity Trade Statistics Database and from individual industry were collected and analyzed for materials flow analysis of neodymium. Demand of neodymium in the Republic of Korea for the year 2010 was 409.5 tons out of which the majority of neodymium, i.e., 68.41% was consumed by domestic electronics industry followed by medical appliances manufacturing (13.36%). The Republic Korea is one of the biggest consumer and leading exporter of these industrial products, absolutely depends on import of neodymium, as the country is lacking natural resources. The Republic of Korea has imported 325.9 tons of neodymium permanent magnet and 79.5 tons of neodymium containing equipment parts mainly for electronics, medical appliances, and heavy/light vehicles manufacturing industry. Out of which 95.4 tons of neodymium permanent magnet get exported as an intermediate product and 140.6 tons of neodymium in the form of consumable products get exported. Worldwide the neodymium is at the high end of supply chain critical metal because of increasing demand, scarcity and irreplaceable for technological application. To bring back the neodymium to supply stream the recycling of end of life neodymium-bearing waste can be a feasible option. Out of total domestic consumption, only 21.9 tons of neodymium have been collected and subsequently recycled. From material flow analysis, the requirement for an efficient recycling system and element-wise material flow management for these REEs in the Republic of Korea were realized and recommended.

  11. Calcium silicate insulation structure

    DOEpatents

    Kollie, Thomas G.; Lauf, Robert J.

    1995-01-01

    An insulative structure including a powder-filled evacuated casing utilizes a quantity of finely divided synthetic calcium silicate having a relatively high surface area. The resultant structure-provides superior thermal insulating characteristics over a broad temperature range and is particularly well-suited as a panel for a refrigerator or freezer or the insulative barrier for a cooler or a insulated bottle.

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

    PubMed

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

    2011-05-20

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

  13. Dissociation of cerium(III) and neodymium(III) phthalocyanines

    NASA Astrophysics Data System (ADS)

    Lomova, T. N.

    2015-07-01

    The kinetics of dissociation of phthalocyanine complexes with cerium(III) and neodymium(III) (X)LnPc (X = Cl-, Br-, AcO-) under the action of acetic acid in ethanol with isolation of the macrocyclic ligand depending on the temperature was studied. The kinetic equations with the numerical values of rate constants, activation parameters, and the stoichiometric mechanisms with the limiting simple reaction between the nonionized AcOH molecule and (phthalocyaninato)lanthanide(III) in the axially coordinated ((X)LnPc, cerium complexes) or axially ionized ([(AcOH)LnPc]+X-, neodymium complexes) state were derived by solving the direct and inverse problems. As shown by a comparative analysis of quantitative kinetic data, the state is determined by the electronic structure of the metal cation and the mutual effect of the axial and equatorial ligands in the first coordination sphere.

  14. Neodymium-YAG laser vitreolysis in sickle cell retinopathy

    SciTech Connect

    Hrisomalos, N.F.; Jampol, L.M.; Moriarty, B.J.; Serjeant, G.; Acheson, R.; Goldberg, M.F.

    1987-08-01

    Six patients with proliferative sickle cell retinopathy and vitreous bands were treated with the neodymium-YAG (Nd-YAG) laser to accomplish lysis of avascular traction bands or to clear the media in front of the macula. Transection of bands was possible in five of the six cases but in two of these the effect was only partial. Three cases were satisfactorily treated with the Nd-YAG laser application alone, two eventually required conventional vitreoretinal surgery, and one patient's condition stabilized despite failure of the treatment. Complications from the treatment occurred in three cases and included subretinal (choroidal) hemorrhage, preretinal hemorrhage, microperforation of a retinal vein, and focal areas of damage to the retinal pigment epithelium. Neodymium-YAG vitreolysis may be a useful modality in carefully selected patients with proliferative sickle cell retinopathy, but potentially sight-threatening complications may occur.

  15. Comment on "Neodymium-142 evidence for Hadean mafic crust".

    PubMed

    Andreasen, Rasmus; Sharma, Mukul

    2009-07-17

    O'Neil et al. (Reports, 26 September 2008, p. 1828) presented neodymium-142 data for rocks from northern Quebec, Canada, and suggested that these rocks may represent the oldest preserved crustal section on Earth. We argue that the age of the rocks is based on a spurious correlation between rocks that are probably not co-genetic and negative (142)Nd anomalies that may be the result of an analytical artifact.

  16. [Neodymium magnet injury causing nasal fracture: a case report].

    PubMed

    Aykan, Andaç; Güzey, Serbülent; Avşar, Sedat; Öztürk, Serdar

    2015-05-01

    In parallel with technological developments, small size but strong magnets are commonly used in modern devices. In terms of foreign body injuries, magnet injuries are quite rare. However, due to their unique characteristics, there are some difficulties in their management. The magnetic field generated by the magnet affects the surgical instruments and make treatment difficult. In this case report, a nasal injury due to neodymium magnet and our alternative approach for its management was reported.

  17. Complexation of di-amides of dipicolinic acid with neodymium

    SciTech Connect

    Lapka, J.L.; Paulenova, A.

    2013-07-01

    Di-amides have undergone significant studies as possible ligands for use in the partitioning of trivalent minor actinides and lanthanides. The binding affinities of three isomeric ligands with neodymium in acetonitrile solution have been investigated. The stability constants of the metal-ligand complexes formed between different isomers of N,N'-diethyl-N,N'- ditolyl-di-picolinamide (EtTDPA) and trivalent neodymium in acetonitrile have been determined by spectrophotometric and calorimetric methods. Each isomer of EtTDPA has been found to be capable of forming three complexes with trivalent neodymium, Nd(EtTDPA), Nd(EtTDPA){sub 2}, and Nd(EtTDPA){sub 3}. Values from spectrophotometric and calorimetric titrations are within reasonable agreement with each other. The order of stability constants for each metal:ligand complex decreases in the order Et(m)TDPA > Et(p)TDPA > Et(o)TDPA. The obtained values are comparable to other di-amidic ligands obtained under similar system conditions and mirror previously obtained solvent extraction data for EtTDPA at low ionic strengths. (authors.

  18. Silicates in Alien Asteroids

    NASA Technical Reports Server (NTRS)

    2009-01-01

    This plot of data from NASA's Spitzer Space Telescopes shows that asteroid dust around a dead 'white dwarf' star contains silicates a common mineral on Earth. The data were taken primarily by Spitzer's infrared spectrograph, an instrument that breaks light apart into its basic constituents. The yellow dots show averaged data from the spectrograph, while the orange triangles show older data from Spitzer's infrared array camera. The white dwarf is called GD 40.

  19. Silicates in Alien Asteroids

    NASA Technical Reports Server (NTRS)

    2009-01-01

    This plot of data from NASA's Spitzer Space Telescopes shows that asteroid dust around a dead 'white dwarf' star contains silicates a common mineral on Earth. The data were taken primarily by Spitzer's infrared spectrograph, an instrument that breaks light apart into its basic constituents. The yellow dots show averaged data from the spectrograph, while the orange triangles show older data from Spitzer's infrared array camera. The white dwarf is called GD 40.

  20. Thermochemistry of Silicates

    NASA Technical Reports Server (NTRS)

    Costa, Gustavo; Jacobson, Nathan

    2015-01-01

    The thermodynamic properties of vapor and condensed phases of silicates are crucial in many fields of science. These quantities address fundamental questions on the formation, stability, transformation, and physical properties of silicate minerals and silicate coating compositions. Here the thermodynamic activities of silica and other species in solid solution have been measured by the analysis of the corresponding high temperature vapors using Knudsen Effusion Mass Spectrometry (KEMS). In first set of experiments KEMS has been used to examine the volatility sequence of species (Fe, SiO, Mg, O2 and O) present in the vapor phase during heating of fosterite-rich olivine (Fo93Fa7) up to 2400 C and to measure the Fe, SiO and Mg activities in its solid solution. The data of fosterite-rich olivine are essential for thermochemical equilibrium models to predict the atmospheric and surface composition of hot, rocky exoplanets (Lava Planets). In the second set of experiments the measured thermodynamic activities of the silica in Y2O3-SiO2 and Yb2O3-SiO2 systems are used to assess their reactivity and degradation recession as environmental barrier coatings (EBCs) in combustion environments (e.g. non-moveable parts of gas turbine engine).

  1. Isotope effects of neodymium in different ligands exchange systems studied by ion exchange displacement chromatography

    PubMed Central

    Ismail, Ibrahim; Fawzy, Ahmed S.; Ahmad, Mohammad I.; Aly, Hisham F.; Nomura, Masao; Fujii, Yasuhiko

    2012-01-01

    The isotope effects of neodymium in Nd-glycolate ligand exchange system were studied by using ion exchange chromatography. The separation coefficients of neodymium isotopes, ε’s, were calculated from the observed isotopic ratios at the front and rear boundaries of the neodymium adsorption band. The values of separation coefficients of neodymium isotopes, ε’s, for the Nd-glycolate ligand exchange system were compared with those of Nd-malate and Nd-citrate, which indicated that the isotope effects of neodymium as studied by the three ligands takes the following direction Malate > Citrate > Glycolate. This order agrees with the number of available sites for complexation of each ligand. The values of the plate height, HETP of Nd in Nd-ligand exchange systems were also calculated. PMID:25685410

  2. Isotope effects of neodymium in different ligands exchange systems studied by ion exchange displacement chromatography.

    PubMed

    Ismail, Ibrahim; Fawzy, Ahmed S; Ahmad, Mohammad I; Aly, Hisham F; Nomura, Masao; Fujii, Yasuhiko

    2013-03-01

    The isotope effects of neodymium in Nd-glycolate ligand exchange system were studied by using ion exchange chromatography. The separation coefficients of neodymium isotopes, ε's, were calculated from the observed isotopic ratios at the front and rear boundaries of the neodymium adsorption band. The values of separation coefficients of neodymium isotopes, ε's, for the Nd-glycolate ligand exchange system were compared with those of Nd-malate and Nd-citrate, which indicated that the isotope effects of neodymium as studied by the three ligands takes the following direction Malate > Citrate > Glycolate. This order agrees with the number of available sites for complexation of each ligand. The values of the plate height, HETP of Nd in Nd-ligand exchange systems were also calculated.

  3. Do foraminifera accurately record seawater neodymium isotope composition?

    NASA Astrophysics Data System (ADS)

    Scrivner, Adam; Skinner, Luke; Vance, Derek

    2010-05-01

    Palaeoclimate studies involving the reconstruction of past Atlantic meridional overturning circulation increasingly employ isotopes of neodymium (Nd), measured on a variety of sample media (Frank, 2002). In the open ocean, Nd isotopes are a conservative tracer of water mass mixing and are unaffected by biological and low-temperature fractionation processes (Piepgras and Wasserburg, 1987; Lacan and Jeandel, 2005). For decades, benthic foraminifera have been widely utilised in stable isotope and geochemical studies, but have only recently begun to be exploited as a widely distributed, high-resolution Nd isotope archive (Klevenz et al., 2008), potentially circumventing the difficulties associated with other methods used to recover past deep-water Nd isotopes (Klevenz et al., 2008; Rutberg et al., 2000; Tachikawa et al., 2004). Thus far, a single pilot study (Klevenz et al., 2008) has indicated that core-top sedimentary benthic foraminifera record a Nd isotope composition in agreement with the nearest available bottom seawater data, and has suggested that this archive is potentially useful on both millennial and million-year timescales. Here we present seawater and proximal core-top foraminifer Nd isotope data for samples recovered during the 2008 "RETRO" cruise of the Marion Dufresne. The foraminifer samples comprise a depth-transect spanning 3000m of the water column in the Angola Basin and permit a direct comparison between high-resolution water column and core-top foraminiferal Nd isotope data. We use these data to assess the reliability of both planktonic and benthic foraminifera as recorders of water column neodymium isotope composition. Frank, M., 2002. Radiogenic isotopes: Tracers of past ocean circulation and erosional input, Rev. Geophys., 40 (1), 1001, doi:10.1029/2000RG000094. Klevenz, V., Vance, D., Schmidt, D.N., and Mezger, K., 2008. Neodymium isotopes in benthic foraminifera: Core-top systematics and a down-core record from the Neogene south Atlantic

  4. Local immunity in treating skin melanoma by neodymium pulsed laser

    NASA Astrophysics Data System (ADS)

    Moskalik, Konstantin G.

    1997-06-01

    The number and correlation of skin stroma cells was studied on mice C57B1 with the subcutaneously transplanted melanoma B16 which was exposed to neodymium pulsed laser radiation. Within 1-5 days after the exposure the total number of the free skin stroma cells was found to increase in the periphery from the radiation epicenter and the number of lymphocytes, macrophages and leucocytes tended to grow. Lymphoid infiltration was also revealed in the preparations of the epithelized wound and cicatrix on the skin melanoma sites in the patients who had undergone pulsed laser radiation therapy.

  5. Pulsed neodymium-YAG laser trabeculotomy: energy requirements and replicability.

    PubMed Central

    Dutton, G N; Allan, D; Cameron, S A

    1989-01-01

    Short pulsed laser trabeculotomy has been shown to reduce intraocular pressure in patients with primary open angle glaucoma. This study seeks to determine the energy levels required to produce a fistula into the canal of Schlemm for four different Q-switched neodymium-YAG lasers. The laser was fired at fixed human trabecular meshwork specimens at a range of energy settings for each laser and the characteristics and replicability of the lesions produced were analysed. Energy levels between 3 and 5 mJ were sufficient to produce fistulae into the canal of Schlemm with an approximately 50% success rate for each instrument. Images PMID:2706207

  6. Effect of transscleral neodymium: YAG cyclophotocoagulation on intraocular lenses

    SciTech Connect

    Blomquist, P.H.; Gross, R.L.; Koch, D.D. )

    1990-03-01

    A neodymium: YAG laser operating in the thermal mode was used to irradiate isolated intraocular lenses (IOLs) and to perform transscleral cyclophotocoagulation on pseudophakic autopsy eyes to investigate the potential damage to IOL haptics such irradiation may cause. In the isolated IOLs, 70 mJ of energy deformed and partially melted both polymethylmethacrylate (PMMA) and polypropylene haptics. One of the capsular-fixated PC-IOL haptics in an autopsy eye partially melted when irradiated with the maximum energy level (8.8 J), with the aiming beam focused 1 mm posterior to the limbus and maximal posterior focus offset.

  7. 21 CFR 182.2906 - Tricalcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Tricalcium silicate. (a) Product. Tricalcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This substance is generally recognized as safe when used in table salt...

  8. 21 CFR 582.2906 - Tricalcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Tricalcium silicate. (a) Product. Tricalcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This substance is generally recognized as safe when used in table salt...

  9. 21 CFR 182.2906 - Tricalcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Tricalcium silicate. (a) Product. Tricalcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This substance is generally recognized as safe when used in table salt...

  10. 21 CFR 582.2906 - Tricalcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Tricalcium silicate. (a) Product. Tricalcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This substance is generally recognized as safe when used in table salt...

  11. 21 CFR 582.2906 - Tricalcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Tricalcium silicate. (a) Product. Tricalcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This substance is generally recognized as safe when used in table salt...

  12. 21 CFR 182.2906 - Tricalcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Tricalcium silicate. (a) Product. Tricalcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This substance is generally recognized as safe when used in table salt...

  13. 21 CFR 582.2906 - Tricalcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Tricalcium silicate. (a) Product. Tricalcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This substance is generally recognized as safe when used in table salt...

  14. 21 CFR 182.2906 - Tricalcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... Tricalcium silicate. (a) Product. Tricalcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This substance is generally recognized as safe when used in table salt...

  15. 21 CFR 582.2906 - Tricalcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Tricalcium silicate. (a) Product. Tricalcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This substance is generally recognized as safe when used in table salt...

  16. Abundance analysis of neodymium in the solar atmosphere

    NASA Astrophysics Data System (ADS)

    Abdelkawy, Ali G. A.; Shaltout, Abdelrazek M. K.; Beheary, M. M.; Bakry, A.

    2017-10-01

    Based on non-local thermodynamical equilibrium (NLTE) calculations, the solar neodymium (Nd) content was found based on a model atom of singly ionized neodymium (Nd ii) containing 153 energy levels and 42 line transitions plus the ground state of Nd iii. Here, we re-derive the solar Nd abundance using the model of the solar photosphere of Holweger & Müller.We succeed in selecting a good sample line list, relying on 20 Nd ii solar lines together with the most accurate transition probabilities measured experimentally and available observational data. With damping parameters obtained from the literature, we find a mean NLTE solar photospheric Nd abundance of log ɛNd(1D) = 1.43 ± 0.16, which is in excellent agreement with the meteoritic value (log ɛNd = 1.45 ± 0.02). For a set of selected Nd ii lines, the NLTE abundance correction is found to be +0.01 dex compared with the standard LTE effect. The influence of collisional interactions with electrons and neutral hydrogen atoms is investigated in detail.

  17. Incorporation of cerium and neodymium in uranyl phases

    NASA Astrophysics Data System (ADS)

    Kim, Cheol-Woon; Wronkiewicz, David J.; Finch, Robert J.; Buck, Edgar C.

    2006-07-01

    The potential for incorporating rare earth elements (REE) into/onto crystalline compounds has been evaluated by precipitating uranyl phases from aqueous solutions containing either cerium or neodymium. These REEs serve both as monitors for evaluating the potential repository behavior of REE radionuclides, and as surrogate elements for actinides (e.g., Ce 4+ and Nd 3+ for Pu 4+ and Am 3+, respectively). The present experiments examined the behavior of REE in the presence of ianthinite ([U24+(UO2)4O6(OH)4(H2O)4](H2O)5), becquerelite (Ca(UO 2) 6O 4(OH) 6(H 2O) 8), and other uranyl hydroxide compounds commonly noted as alteration products during the corrosion of UO 2, spent nuclear fuel, and naturally occurring uraninite. The results of these experiments demonstrate that significant quantities of both cerium ( Kd = 1020) and neodymium ( Kd = 840) are incorporated within the uranium alteration phases and suggest that ionic substitution and/or adsorption to the uranyl phases can play a key role in the limiting the mobility of REE (and by analogy, actinide elements) in a nuclear waste repository.

  18. Magnetic behaviour of Neodymium-substituted strontium hexaferrite

    NASA Astrophysics Data System (ADS)

    Bhat, Bilal Hamid; Want, Basharat

    2016-03-01

    Neodymium-substituted strontium hexaferrites, Sr1- x Nd x Fe12O19 ( x = 0, 0.05, 0.10, 0.15, 0.20), have been successfully synthesized by using citrate precursor method. The synthesized samples were characterized by X-ray diffraction, Transmission electron microscopy and vibrating sample magnetometry. The X-ray diffraction results show that the prepared samples are crystalline in nature and are of single phase with the space group P63/mmc. Transmission electron microscopy results show that the prepared sample is composed of fine nanoparticles with an average size of 80 nm. The effect on magnetic behaviour of strontium hexaferrite with neodymium substitution was analysed by using first-order reversal curves (FORCs). FORC analysis was done in order to know the domain state of magnetization of the nanoparticles and the nature of magnetic interactions among the particles. FORC diagrams depict a single peak, suggesting that the substituted systems are formed of interacting nanoparticles.

  19. Origin of the Sudbury Complex by meteoritic impact: Neodymium isotopic evidence

    USGS Publications Warehouse

    Faggart, B.E.; Basu, A.R.; Tatsumoto, M.

    1985-01-01

    Samarium-neodymium isotopic data on whole rocks and minerals of the Sudbury Complex in Canada gave an igneous crystallization age of 1840 ?? 21 ?? 106 years. The initial epsilon neodymium values for 15 whole rocks are similar to those for average upper continental crust, falling on the crustal trend of neodymium isotopic evolution as defined by shales. The rare earth element concentration patterns of Sudbury rocks are also similar to upper crustal averages. These data suggest that the Sudbury Complex formed from melts generated in the upper crust and are consistent with a meteoritic impact.

  20. Electrolytic production of neodymium without perfluorinated carbon compounds on the offgases

    DOEpatents

    Keller, Rudolf; Larimer, Kirk T.

    1998-01-01

    A method of producing neodymium in an electrolytic cell without formation of perfluorinated carbon gases (PFCs), the method comprising the steps of providing an electrolyte in the electrolytic cell and providing an anode in an anode region of the electrolyte and providing a cathode in a cathode region of the electrolytic cell. Dissolving an oxygen-containing neodymium compound in the electrolyte in the anode region and maintaining a more intense electrolyte circulation in the anode region than in the cathode region. Passing an electrolytic current between said anode and said cathode and depositing neodymium metal at the cathode, preventing the formation of perfluorinated carbon gases by limiting anode over voltage.

  1. Analysis of a Sheet Silicate.

    ERIC Educational Resources Information Center

    Adams, J. M.; Evans, S.

    1980-01-01

    Describes a student project in analytical chemistry using sheet silicates. Provides specific information regarding the use of phlogopite in an experiment to analyze samples for silicon, aluminum, magnesium, iron, potassium, and fluoride. (CS)

  2. Analysis of a Sheet Silicate.

    ERIC Educational Resources Information Center

    Adams, J. M.; Evans, S.

    1980-01-01

    Describes a student project in analytical chemistry using sheet silicates. Provides specific information regarding the use of phlogopite in an experiment to analyze samples for silicon, aluminum, magnesium, iron, potassium, and fluoride. (CS)

  3. 21 CFR 172.410 - Calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be...

  4. 21 CFR 172.410 - Calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be...

  5. 21 CFR 172.410 - Calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium silicate. 172.410 Section 172.410 Food and... PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Anticaking Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be safely used in food in accordance with...

  6. 21 CFR 172.410 - Calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be...

  7. 21 CFR 172.410 - Calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium silicate. 172.410 Section 172.410 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN... Agents § 172.410 Calcium silicate. Calcium silicate, including synthetic calcium silicate, may be...

  8. Analysis of the structure and Mössbauer study of the neodymium substitution in the Sr-hexaferrite

    NASA Astrophysics Data System (ADS)

    Pérez-Juache, T. J.; Guerrero, A. L.; Cabal-Velarde, J. G.; Mirabal-García, M.; Palomares-Sánchez, S. A.; Matutes-Aquino, J. A.

    2016-12-01

    This work reads on the obtainment of the strontium hexaferrite substituted with neodymium in its pure phase using the solid state reaction method. The solubility of neodymium on the strontium hexaferrite was investigated according with the formula Sr1-xNdxFe12O19, for x=0.00, 0.05, 0.10, 0.15, 0.20 and 0.25. Results indicate that neodymium is soluble in the hexaferrite until x=0.15. In samples with higher neodymium content there are traces of secondary phases. Analysis of magnetic and structural properties was performed in function of the neodymium content, always in its solubility range. From the structural properties, it was observed that the addition of a little neodymium quantity in the Sr-hexaferrite causes an important reduction of the unit cell volume. Also, magnetic properties are strongly linked to the structural behavior, in this case a trend to reduce the magnetization of the samples was detected when neodymium content increased, which can be explained in terms of fluctuations of the superexchange coupling conducted by the neodymium interactions with the structure. Mössbauer analysis was carried out in order to analyze the effects of the neodymium substitution on the hyperfine parameters, as well as to confirm the preferential site of the neodymium substitution in the Sr-hexaferrite.

  9. THE BIOCOMPATIBILITY OF MESOPOROUS SILICATES

    PubMed Central

    Hudson, Sarah; Padera, Robert F.; Langer, Robert; Kohane, Daniel S.

    2008-01-01

    Micro- and nano- mesoporous silicate particles are considered potential drug delivery systems because of their ordered pore structures, large surface areas and the ease with which they can be chemically modified. However, few cytotoxicity or biocompatibility studies have been reported, especially when silicates are administered in the quantities necessary to deliver low-potency drugs. The biocompatibility of mesoporous silicates of particle sizes ~ 150 nm, ~ 800 nm and ~ 4 µm and pore sizes of 3 nm, 7 nm and 16 nm respectively are examined here. In vitro, mesoporous silicates showed a significant degree of toxicity at high concentrations with mesothelial cells. Following subcutaneous injection of silicates in rats, the amount of residual material decreased progressively over three months, with good biocompatibility on histology at all time points. In contrast, intra peritoneal and intra venous injections in mice resulted in death or euthanasia. No toxicity was seen with subcutaneous injection of the same particles in mice. Microscopic analysis of the lung tissue of the mice indicates that death may be due to thrombosis. Although local tissue reaction to mesoporous silicates was benign, they caused severe systemic toxicity. This toxicity could be mitigated by modification of the materials. PMID:18675454

  10. A new contact neodymium: YAG laser for cyclophotocoagulation

    SciTech Connect

    Iwach, A.G.; Drake, M.V.; Hoskins, H.D. Jr.; Schuster, B.L.; Vassiliadis, A.; Crawford, J.B.; Hennings, D.R. )

    1991-06-01

    A newly developed compact (40 kg), self-contained contact Neodymium:YAG laser produces high-peak, high-energy (800 mJ/pulse), short (1.0 millisecond) pulses with 1 to 3 pulses/exposure. Energy is delivered via a 320-microns cleaved quartz fiber optic probe. Cyclophotocoagulation was performed in five eyes of three medium-sized Dutch-pigmented rabbits. The eyes received exposures of 1 to 3 pulses/exposure. Energy delivered ranged from 100 to 800 mJ/pulse. Histopathology revealed ciliary body disruption and hemorrhage with no damage to overlying sclera. When used for transscleral cyclodiathermy in the rabbit, the laser created significant ciliary body disruption with minimal scleral injury.

  11. Segmental irradiation of the bladder with neodymium YAG laser irradiation

    SciTech Connect

    McPhee, M.S.; Mador, D.R.; Tulip, J.; Ritchie, B.; Moore, R.; Lakey, W.H.

    1982-11-01

    The Neodymium YAG laser energy source can be readily adapted for cystoscopic use by some simple modifications of existing urologic equipment. Both the fiberoptic resectoscope and a deflecting cystourethroscope have been adapted for this purpose. Fixation of the fiber tip 1 cm. from the target and use of a divergent beam of 36 degrees allows the delivery of standardized dosage to a relatively large bladder tissue volume. Animal experiments involving 35 mongrel dogs established that repetitive overlapping doses of 200 joules ech can successfully treat a large area of bladder resulting in a full thickness bladder wall injury. This technique has been used in 4 high risk patients with infiltrating bladder cancer without adverse sequelae. The ability to reliably produce a full thickness lesion may give this modality a therapeutic advantage over conventional cautery techniques especially for the treatment of residual infiltrative carcinoma.

  12. Absolute isotopic composition and atomic weight of neodymium using thermal ionization mass spectrometry.

    PubMed

    Zhao, Motian; Zhou, Tao; Wang, Jun; Lu, Hai; Fang, Xiang; Guo, Chunhua; Li, Qiuli; Li, Chaofeng

    2005-01-01

    Synthetic mixtures prepared gravimetrically from highly enriched isotopes of neodymium in the form of oxides of well-defined purity were used to calibrate a thermal ionization mass spectrometer. A new error analysis was applied to calculate the final uncertainty of the atomic weight value. Measurements on natural neodymium samples yielded an absolute isotopic composition of 27.153(19) atomic percent (at.%) 142Nd, 12.173(18) at.% 143Nd, 23.798(12) at.% 144Nd, 8.293(7) at.% 145Nd, 17.189(17) at.% 146Nd, 5.756(8) at.% 148Nd, and 5.638(9) at.% 150Nd, and the atomic weight of neodymium as 144.2415(13), with uncertainties given on the basis of 95% confidence limits. No isotopic fractionation was found in terrestrial neodymium materials.

  13. Isotope enrichment by frequency-tripled temperature tuned neodymium laser photolysis of formaldehyde

    DOEpatents

    Marling, John B.

    1977-01-01

    Enrichment of carbon, hydrogen and/or oxygen isotopes by means of isotopically selective photo-predissociation of formaldehyde is achieved by irradiation provided by a frequency-tripled, temperature tuned neodymium laser.

  14. Modification of neodymium-doped ZnO hybrid nanoparticles under mild hydrothermal conditions.

    PubMed

    Shahmoradi, Behzad; Soga, K; Ananda, S; Somashekar, R; Byrappa, K

    2010-07-01

    The morphology and particle size of neodymium-doped ZnO hybrid nanoparticles were tailored through fabrication under mild hydrothermal conditions (T = 150-250 degrees C, P = autogeneous, t = 18 h) for the first time using two surface modifiers: caprylic acid and n-butylamine. Characterization of these nanoparticles was carried out using powder XRD, FTIR, SEM, zeta-potential analysis and UV-vis spectroscopy. The results revealed that modification of ZnO nanoparticles using neodymium as a dopant and caprylic acid or n-butylamine as a surfactant could change the optical and physical properties of the surface-modified neodymium-doped ZnO hybrid nanoparticles. The work proved the efficiency of caprylic acid and n-butylamine as suitable surfactants for surface modification of neodymium-doped ZnO hybrid nanoparticles.

  15. Microscale Demonstration of the Paramagnetism of Liquid Oxygen with a Neodymium Magnet

    ERIC Educational Resources Information Center

    Mattson, Bruce

    2007-01-01

    A microscale classroom demonstration of the paramagnetic behavior of various samples of liquid oxygen with neodymium magnet is being presented. The experiment should be done with extreme caution, as liquid oxygen reacts violently with organic matters.

  16. Microscale Demonstration of the Paramagnetism of Liquid Oxygen with a Neodymium Magnet

    ERIC Educational Resources Information Center

    Mattson, Bruce

    2007-01-01

    A microscale classroom demonstration of the paramagnetic behavior of various samples of liquid oxygen with neodymium magnet is being presented. The experiment should be done with extreme caution, as liquid oxygen reacts violently with organic matters.

  17. Tin in silicate melts

    NASA Astrophysics Data System (ADS)

    Paparoni, Guido

    An experimental technique that uses Re metal capsules as containers for tin-bearing systems has been developed and successfully used in the study of the compositional dependence of SnO2 solubility in silicate melts. These experiments have been performed in the absence of an aqueous fluid phase and oxygen fugacity (fO2) has been established by the addition of tin-metal to SnO2. This approach solves three long-standing problems in the study of SnO 2 solubility in silicate melts: (1) Alloying of noble-metal crucibles and corrosion of ceramic crucibles is avoided; (2) fO 2 is established by direct contact of a metal-oxide oxygen buffer; (3) Gaseous SnO is not lost to the furnace atmosphere. The Re-capsule technique, combined with evacuated silica-tube experiments, has been applied to the study of the system SnO-SiO2 at pressures of 1 atm and 10 kbar. SnO2 solubilities of up to 95 wt% SnO are reported. The system SnO-SiO2 is found to be a pseudo-binary of the ternary system Sn°-SnO2-SiO2. A revised phase diagram for the system SnO-SiO2 at a pressure ≈1 atm is provided, and a new phase diagram for the system SnOSiO2 at a pressure = 10 kbar has been constructed. These results are used to suggest the topology of the ternary system Sn°-SnO2SiO2. The Re-capsule technique has also been applied to the study of the subaluminous haplogranite system (SiO2NaAlSi3O8-KAlSi 3O8) at T = 1100°C, P = 10 kbar and fO 2 at Sn°-SnO2. Solubilities span the range of 41 to 80 wt% SnO. In the haplogranite system, the solubility of SnO2 increases with the proportion of normative SiO2, and SnO is found to expand the stability field of SiO2. In the feldspar join, Na-based melts dissolve a larger proportion of SnO than K-based melts. This effect is lost as SiO2 is progressively added to the feldspar join. Small amounts of F (1 wt%) are found to increase the solubility of SnO 2 by an equivalent 15 wt% normative quartz as shown with the Spor Mountain rhyolite. A comparison of SnO2 solubilities

  18. Ultralow-threshold neodymium-doped microsphere lasers on a silicon chip

    NASA Astrophysics Data System (ADS)

    Ding, Yang; Fan, Huibo; Zhang, Xun; Jiang, Xiaoshun; Xiao, Min

    2017-07-01

    We demonstrate ultralow-threshold neodymium-doped silica microsphere lasers on a silicon chip with lasing wavelengths of 900 nm and 1060 nm. Neodymium-doped microsphere cavities are fabricated with a series of doping concentrations using silica sol-gel films. Experimentally, we observe single-mode lasing emissions from the high-Q microsphere cavities with a threshold of as low as 1.2 μW.

  19. Description of the traction characteristics of the neodymium compensators of the automatic vibration isolations

    NASA Astrophysics Data System (ADS)

    Gurova, E. G.; Panchenko, Y. V.; Gurov, M. G.

    2016-04-01

    In this paper the method of calculation of neodymium magnets was presented. The calculation of the neodymium magnets characteristics and stiffness correctors of the vibration isolator according to the requirements for vibration isolation devices with stiffness compensators was performed. This research has been performed with the support of the President scholarship for young scientists, order No. 184 of Ministry of education and science of the Russian Federation of the 10th of March 2015.

  20. Sol-Gel Synthesis and Characterization of Neodymium-Ion Doped Nanostructured Titania Thin Films

    DTIC Science & Technology

    2001-11-01

    reactions, which break down harmful organic pollutants to relatively harmless constituent chemicals. Semiconductor photocatalysis takes advantage of the...UNCLASSIFIED Defense Technical Information Center Compilation Part Notice ADP012201 TITLE: Sol-Gel Synthesis and Characterization of Neodymium-Ion...Society V5.2 SOL-GEL SYNTHESIS AND CHARACTERIZATION OF NEODYMIUM-ION DOPED NANOSTRUCTURED TITANIA THIN FILMS Andrew Burns~ln, W. Li("t, C. Baker"l) and

  1. Neodymium and strontium isotope evidence for crustal contamination of continental volcanics.

    PubMed

    Carter, S R; Evensen, N M; Hamilton, P J; O'nions, R K

    1978-11-17

    Combined neodymium and strontium isotope studies on Tertiary volcanics from northwest Scotland indicate that their parental mantle isotopic compositions have been substantially modified in many instances by contamination with the Precambrian continental crust through which they were erupted. The occurrence of samarium-neodymium and rubidium-strontium "pseudoisochrons" of different ages in these contaminated continental volcanics indicates that they are artifacts of the contamination processes and have no temporal significance with respect to mantle fractionation events.

  2. Thermochemistry of Silicate Speciation in Aqueous Sodium Silicate Solutions: Ionization and Polymerization of Small Silicate Ion

    DTIC Science & Technology

    1993-07-12

    reasonable success, but a number of simplifications were used. For instance, the polymerization equilibrium constants were assumed to be independent of...Another weakness lies in the functionality assumed for the ionization equilibrium constants . As will be discussed below, experimental data that the free...characterize silicate species in fairly complex alkaline silicate solutions and thereby to estimate a large number of equilibrium constants [27,28

  3. Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates

    NASA Astrophysics Data System (ADS)

    Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Flatt, Robert J.; D'Espinose de Lacaillerie, Jean-Baptiste

    2016-03-01

    Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of 29Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the hydration process in terms of transient local molecular composition, extent of silicate hydration and polymerization. This provides insights on the relative influence of surface hydroxylation and hydrate precipitation on the hydration rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured.

  4. Understanding silicate hydration from quantitative analyses of hydrating tricalcium silicates

    PubMed Central

    Pustovgar, Elizaveta; Sangodkar, Rahul P.; Andreev, Andrey S.; Palacios, Marta; Chmelka, Bradley F.; Flatt, Robert J.; d'Espinose de Lacaillerie, Jean-Baptiste

    2016-01-01

    Silicate hydration is prevalent in natural and technological processes, such as, mineral weathering, glass alteration, zeolite syntheses and cement hydration. Tricalcium silicate (Ca3SiO5), the main constituent of Portland cement, is amongst the most reactive silicates in water. Despite its widespread industrial use, the reaction of Ca3SiO5 with water to form calcium-silicate-hydrates (C-S-H) still hosts many open questions. Here, we show that solid-state nuclear magnetic resonance measurements of 29Si-enriched triclinic Ca3SiO5 enable the quantitative monitoring of the hydration process in terms of transient local molecular composition, extent of silicate hydration and polymerization. This provides insights on the relative influence of surface hydroxylation and hydrate precipitation on the hydration rate. When the rate drops, the amount of hydroxylated Ca3SiO5 decreases, thus demonstrating the partial passivation of the surface during the deceleration stage. Moreover, the relative quantities of monomers, dimers, pentamers and octamers in the C-S-H structure are measured. PMID:27009966

  5. Research and development of neodymium phosphate laser glass for high power laser application

    NASA Astrophysics Data System (ADS)

    Hu, Lili; He, Dongbing; Chen, Huiyu; Wang, Xin; Meng, Tao; Wen, Lei; Hu, Junjiang; Xu, Yongchun; Li, Shunguang; Chen, Youkuo; Chen, Wei; Chen, Shubin; Tang, Jingping; Wang, Biao

    2016-12-01

    Neodymium phosphate laser glass is a key optical element for high-power laser facility. In this work, the latest research and development of neodymium phosphate laser glass at the Shanghai Institute of Optics and Fine Mechanics (SIOM), China, is addressed. Neodymium phosphate laser glasses, N31, N41, NAP2, and NAP4, for high peak power and high average power applications have been developed. The properties of these glasses are presented and compared to those of other commercial neodymium phosphate laser glass from the Schott and Hoya companies and the Vavilov State Optical Institute (GOI), Russia. Continuous melting and edge cladding are the two key fabrication techniques that are used for the mass production of neodymium phosphate laser glass slabs. These techniques for the fabrication of large-aperture N31 neodymium phosphate laser glass slabs with low stress birefringence and residual reflectivity have been developed by us The effect of acid etching on the microstructure, optical transmission, and mechanical properties of NAP2 glass is also discussed.

  6. Research and development of neodymium phosphate laser glass for high power laser application

    NASA Astrophysics Data System (ADS)

    Hu, Lili; He, Dongbing; Chen, Huiyu; Wang, Xin; Meng, Tao; Wen, Lei; Hu, Junjiang; Xu, Yongchun; Li, Shunguang; Chen, Youkuo; Chen, Wei; Chen, Shubin; Tang, Jingping; Wang, Biao

    2017-01-01

    Neodymium phosphate laser glass is a key optical element for high-power laser facility. In this work, the latest research and development of neodymium phosphate laser glass at the Shanghai Institute of Optics and Fine Mechanics (SIOM), China, is addressed. Neodymium phosphate laser glasses, N31, N41, NAP2, and NAP4, for high peak power and high average power applications have been developed. The properties of these glasses are presented and compared to those of other commercial neodymium phosphate laser glass from the Schott and Hoya companies and the Vavilov State Optical Institute (GOI), Russia. Continuous melting and edge cladding are the two key fabrication techniques that are used for the mass production of neodymium phosphate laser glass slabs. These techniques for the fabrication of large-aperture N31 neodymium phosphate laser glass slabs with low stress birefringence and residual reflectivity have been developed by us The effect of acid etching on the microstructure, optical transmission, and mechanical properties of NAP2 glass is also discussed.

  7. Diffusion kinetics of samarium and neodymium in garnet, and a method for determining cooling rates of rocks

    PubMed

    Ganguly; Tirone; Hervig

    1998-08-07

    Experimental determinations of the diffusion coefficients of samarium and neodymium in almandine garnet and theoretical considerations show that one cannot assign a sufficiently restricted range of closure temperature, TC, to the samarium-neodymium decay system in garnet for the purpose of constraining the cooling rate. However, it is shown that the samarium-neodymium cooling age of garnet can be used to calculate both cooling rate and TC if the temperature and age at the peak metamorphic conditions are known.

  8. Comparative pathology of silicate pneumoconiosis.

    PubMed Central

    Brambilla, C.; Abraham, J.; Brambilla, E.; Benirschke, K.; Bloor, C.

    1979-01-01

    A simple pneumoconiosis with lamellar birefringent crystals was observed in animals dying in the San Diego Zoo. We studied 100 autopsies from 11 mammalian and eight avian species. In mammals, mild pulmonary lesions comprised crystal-laden macrophages in alveoli and lymphatics. Interstitial fibrosis was present in 20% of cases. There were no nodules. In birds, dust retention produced large granulomas around tertiary bronchi without fibrosis. Mineralogic analysis using scanning and transmission electron microscopy showed most of the crystals to be silicates. Ninety percent were complex silicates, with aluminum-potassium silicates comprising 70% of the analyzed particles. Electron and x-ray diffraction showed the silicates to be muscovite mica and its hydrothermal degradation product, ie, illite clay. This mica was also present on filtration membranes of atmospheric air samples obtained from the San Diego Zoo. The amount of dust retention was related to the animal's age, anatomic or ecologic variances, and length of stay in the San Diego Zoo. Its semidesert atmosphere is rich in silicates, which are inhaled and deposited in the lungs. Similar mica-induced lesions are found in humans living in this region or the Southwest of the USA. This simple pneumoconiosis is likely to be widespread in human populations living in desert or semidesert climates. Images Figure 9 Figure 10 Figure 7 Figure 8 Figure 5 Figure 6 Figure 1 Figure 2 Figure 3 Figure 4 PMID:223447

  9. Thermoluminescent sensitivity of single clad neodymium doped SiO2 optical fibres measured with 6 MeV photons

    NASA Astrophysics Data System (ADS)

    Saeed, M. A.; Hossain, I.; Hida, N.; Wagiran, H.

    2013-10-01

    This study investigates the thermoluminescent sensitivity of neodymium doped SiO2 optical fibre with various dose ranges from 0.5 Gy to 4.0 Gy by 6 MeV photon irradiations. The TL responses of the neodymium doped silica fibres are compared with available TLD-100 dosimeter in order to determine the suitability as a TL material. We found that the TLD-100 and neodymium doped silica fibre have a significant linear signal to dose relationship. Neodymium doped fibres sensitivity is approximately 11% of TLD-100.

  10. Rare earth elements and neodymium isotopes in world river sediments revisited

    NASA Astrophysics Data System (ADS)

    Bayon, G.; Toucanne, S.; Skonieczny, C.; André, L.; Bermell, S.; Cheron, S.; Dennielou, B.; Etoubleau, J.; Freslon, N.; Gauchery, T.; Germain, Y.; Jorry, S. J.; Ménot, G.; Monin, L.; Ponzevera, E.; Rouget, M.-L.; Tachikawa, K.; Barrat, J. A.

    2015-12-01

    Over the past decades, rare earth elements (REE) and their radioactive isotopes have received tremendous attention in sedimentary geochemistry, as tracers for the geological history of the continental crust and provenance studies. In this study, we report on elemental concentrations and neodymium (Nd) isotopic compositions for a large number of sediments collected near the mouth of rivers worldwide, including some of the world's major rivers. Sediments were leached for removal of non-detrital components, and both clay and silt fractions were retained for separate geochemical analyses. Our aim was to re-examine, at the scale of a large systematic survey, whether or not REE and Nd isotopes could be fractionated during Earth surface processes. Our results confirmed earlier assumptions that river sediments do not generally exhibit any significant grain-size dependent Nd isotopic variability. Most sediments from rivers draining old cratonic areas, sedimentary systems and volcanic provinces displayed similar Nd isotopic signatures in both clay and silt fractions, with ΔεNd(clay-silt) < |1|. A subtle decoupling of Nd isotopes between clays and silts was identified however in a few major river systems (e.g. Nile, Mississippi, Fraser), with clays being systematically shifted towards more radiogenic values. This observation suggests that preferential weathering of volcanic and/or sedimentary rocks relative to more resistant lithologies may occur in river basins, possibly leading locally to Nd isotopic decoupling between different size fractions. Except for volcanogenic sediments, silt fractions generally displayed homogeneous REE concentrations, exhibiting relatively flat shale-normalized patterns. However, clay fractions were almost systematically characterized by a progressive enrichment from the heavy to the light REE and a positive europium (Eu) anomaly. In agreement with results from previous soil investigations, the observed REE fractionation between clays and silts

  11. Evidence of silicic acid leakage to the tropical Atlantic via Antarctic Intermediate Water during Marine Isotope Stage 4

    NASA Astrophysics Data System (ADS)

    Griffiths, James D.; Barker, Stephen; Hendry, Katharine R.; Thornalley, David J. R.; van de Flierdt, Tina; Hall, Ian R.; Anderson, Robert F.

    2013-06-01

    Antarctic Intermediate Water (AAIW) and Subantarctic Mode Water (SAMW) are the main conduits for the supply of dissolved silicon (silicic acid) from the deep Southern Ocean (SO) to the low-latitude surface ocean and therefore have an important control on low-latitude diatom productivity. Enhanced supply of silicic acid by AAIW (and SAMW) during glacial periods may have enabled tropical diatoms to outcompete carbonate-producing phytoplankton, decreasing the relative export of inorganic to organic carbon to the deep ocean and lowering atmospheric pCO2. This mechanism is known as the "silicic acid leakage hypothesis" (SALH). Here we present records of neodymium and silicon isotopes from the western tropical Atlantic that provide the first direct evidence of increased silicic acid leakage from the Southern Ocean to the tropical Atlantic within AAIW during glacial Marine Isotope Stage 4 ( 60-70 ka). This leakage was approximately coeval with enhanced diatom export in the NW Atlantic and across the eastern equatorial Atlantic and provides support for the SALH as a contributor to CO2 drawdown during full glacial development.

  12. Final report on the safety assessment of aluminum silicate, calcium silicate, magnesium aluminum silicate, magnesium silicate, magnesium trisilicate, sodium magnesium silicate, zirconium silicate, attapulgite, bentonite, Fuller's earth, hectorite, kaolin, lithium magnesium silicate, lithium magnesium sodium silicate, montmorillonite, pyrophyllite, and zeolite.

    PubMed

    Elmore, Amy R

    2003-01-01

    This report reviews the safety of Aluminum, Calcium, Lithium Magnesium, Lithium Magnesium Sodium, Magnesium Aluminum, Magnesium, Sodium Magnesium, and Zirconium Silicates, Magnesium Trisilicate, Attapulgite, Bentonite, Fuller's Earth, Hectorite, Kaolin, Montmorillonite, Pyrophyllite, and Zeolite as used in cosmetic formulations. The common aspect of all these claylike ingredients is that they contain silicon, oxygen, and one or more metals. Many silicates occur naturally and are mined; yet others are produced synthetically. Typical cosmetic uses of silicates include abrasive, opacifying agent, viscosity-increasing agent, anticaking agent, emulsion stabilizer, binder, and suspending agent. Clay silicates (silicates containing water in their structure) primarily function as adsorbents, opacifiers, and viscosity-increasing agents. Pyrophyllite is also used as a colorant. The International Agency for Research on Cancer has ruled Attapulgite fibers >5 microm as possibly carcinogenic to humans, but fibers <5 microm were not classified as to their carcinogenicity to humans. Likewise, Clinoptilolite, Phillipsite, Mordenite, Nonfibrous Japanese Zeolite, and synthetic Zeolites were not classified as to their carcinogenicity to humans. These ingredients are not significantly toxic in oral acute or short-term oral or parenteral toxicity studies in animals. Inhalation toxicity, however, is readily demonstrated in animals. Particle size, fibrogenicity, concentration, and mineral composition had the greatest effect on toxicity. Larger particle size and longer and wider fibers cause more adverse effects. Magnesium Aluminum Silicate was a weak primary skin irritant in rabbits and had no cumulative skin irritation in guinea pigs. No gross effects were reported in any of these studies. Sodium Magnesium Silicate had no primary skin irritation in rabbits and had no cumulative skin irritation in guinea pigs. Hectorite was nonirritating to the skin of rabbits in a Draize primary skin

  13. 21 CFR 872.6670 - Silicate protector.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6670 Silicate protector. (a) Identification. A silicate... system regulation in part 820 of this chapter, with the exception of § 820.180, with respect to general...

  14. Battery components employing a silicate binder

    DOEpatents

    Delnick, Frank M [Albuquerque, NM; Reinhardt, Frederick W [Albuquerque, NM; Odinek, Judy G [Rio Rancho, NM

    2011-05-24

    A battery component structure employing inorganic-silicate binders. In some embodiments, casting or coating of components may be performed using aqueous slurries of silicates and electrode materials or separator materials.

  15. Circumstellar Crystalline Silicates: Evolved Stars

    NASA Astrophysics Data System (ADS)

    Tartar, Josh; Speck, A. K.

    2008-05-01

    One of the most exciting developments in astronomy in the last 15 years was the discovery of crystalline silicate stardust by the Short Wavelength Spectrometer (SWS) on board of ISO; discovery of the crystalline grains was indeed one of the biggest surprises of the ISO mission. Initially discovered around AGB stars (evolved stars in the range of 0.8 > M/M¤>8) at far-infrared (IR) wavelengths, crystalline silicates have since been seen in many astrophysical environments including young stellar objects (T Tauri and Herbig Ae/Be), comets and Ultra Luminous Infrared Galaxies. Low and intermediate mass stars (LIMS) comprise 95% of the contributors to the ISM, so study of the formation of crystalline silicates is critical to our understanding of the ISM, which is thought to be primarily amorphous (one would expect an almost exact match between the composition of AGB dust shells and the dust in the ISM). Whether the crystalline dust is merely undetectable or amorphized remains a mystery. The FORCAST instrument on SOFIA as well as the PACS instrument on Herschel will provide exciting observing opportunities for the further study of crystalline silicates.

  16. Femtosecond diode-pumped mode-locked neodymium lasers

    NASA Astrophysics Data System (ADS)

    Kubeček, Václav; Jelínek, Michal; Čech, Miroslav; Vyhlídal, David; Su, Liangbi; Jiang, Dapeng; Ma, Fengkai; Qian, Xiaobo; Wang, Jingya; Xu, Jun

    2016-12-01

    Fluoride-type crystals (CaF2, SrF2) doped with neodymium Nd3+ and codoped with buffer ions for breaking clusters of active ions and increasing fluorescence efficiency, present interesting alternative as laser active media for the diode-pumped mode-locked lasers. In comparison with widely used materials as Nd:YAG or Nd:YVO4, they have broad emission spectra as well as longer fluorescence lifetime, in comparison with Nd:glass, SrF2 and CaF2 have better thermal conductivity. In spite of the fact, that this thermal conductivity decreases with Nd3+ doping concentration, these crystals are alternative for the Nd:glass in subpicosecond mode-locked laser systems. In this paper we review the basic results reported recently on these active materials and in the second part we present our results achieved in low power diode pumped passively mode locked lasers with Nd,La:CaF2 and Nd,Y:SrF2 crystals. The pulses as short as 258 fs at wavelength of 1057 nm were obtained in the first case, while 5 ps long pulses at 1065 nm were generated from the second laser system.

  17. Defluoridation of water using neodymium-modified chitosan.

    PubMed

    Yao, Ruihua; Meng, Fanping; Zhang, Longjun; Ma, Dongdong; Wang, Mingli

    2009-06-15

    The water containing high fluoride ions could do harm to human and environment. In this work, the applicability of neodymium-modified chitosan as adsorbents for the removal of excess fluoride ions from water was studied. The effect of various physico-chemical parameters such as temperature (283-323 K), pH (5-9), adsorbent dose (0.2-2.0 g L(-1)), particle size (0.10-0.50mm) and the presence of co-anions (NO(3)(-), Cl(-) and SO(4)(2-)) on removal of fluoride ions were studied. The equilibrium sorption data were fitted reasonably well for Langmuir isotherm model, the maximum equilibrium sorption had found to be 11.411-22.380 mg g(-1). Sorption dynamics study revealed that the pseudo-second-order was suitable to describe the kinetics process of fluoride ions sorption onto the adsorbent with the initial sorption rate 1.70, 2.10 and 2.67 mg g(-1)min(-1) at 283, 303 and 323 K, and the sorption process was complex, both the boundary of liquid film and intra-particle diffusion contributed to the rate-determining step. The used adsorbents could be regenerated in 24h by 4 g L(-1) of sodium hydroxide.

  18. Effect Of Neodymium Substitution In Structural Characteristics Of Magnesium Ferrite

    SciTech Connect

    Thankachan, Smitha; Binu, P. J.; Xavier, Sheena; Mohammed, E. M.

    2011-10-20

    The effect of Nd{sup 3+} substitution on the structural properties of Magnesium ferrite was studied in the series MgNd{sub x}Fe{sub 2-x}O{sub 4}, where x = 0 to 0.3 in steps of 0.05. The series was prepared by sol-gel technique which is one of the novel technique to prepare nanosized samples. Structural characterization was done using X-ray diffractometer and Fourier Transform Infrared Spectrometer. XRD analysis reveals the prepared samples are single phasic till x = 0.2. From x0 = .25, a secondary phase of iron neodymium oxide appears along with the spinel phase. Particle size calculation shows the prepared samples are in the 9nm to 11 nm regime. Lattice parameter was found to increase with concentration of Nd. XRD and FTIR analysis confirmed spinel structure of the prepared samples. XRF result shows the expected composition of prepared samples. The frequency dependence of the dielectric constant in the range 100 Hz--120MHz was also studied

  19. Dielectric properties of neodymium-modified PLZT ceramics

    NASA Astrophysics Data System (ADS)

    Płońska, M.; Adamczyk, M.

    2015-08-01

    Relaxor ferroelectrics or relaxors are a class of disordered single crystals and ceramic materials, of peculiar structure as well as properties. The commonly known examples of such materials are Pb(Mg,Nb)O3 (PMN) ceramics as well as single crystals. The second most extensively studied relaxor ceramics is lanthanum-doped lead zirconate-titanate, described as x/65/35 PLZT when lanthanum content is x = 6-10 at%. Throughout the last few decades, there has been an increasing interest in rare-earth-doped PLZT ceramics, because PLZT can be easily substituted with lanthanide elements for La3+ ions. For this reason, the present studies concern the changes in microstructure and crystal structure as well as in dielectric properties, caused by modification of 8/65/35 PLZT with neodymium dopant. Modification of this material with Nd3+ influences the microstructure, electrooptical and dielectric properties, whereas the changes in crystal structure are slight. It was also observed that the maximum value of dielectric properties decreases and moves to a low temperature. Described changes in physical properties are associated with the significant improvement of relaxor properties, characteristic for pure 8/65/35 PLZT ceramics.

  20. Early tissue response to transscleral neodymium: YAG cyclophotocoagulation.

    PubMed

    Blasini, M; Simmons, R; Shields, M B

    1990-06-01

    Transscleral cyclophotocoagulation was performed with a neodymium: YAG laser on five patients 24-72 hr before enucleation for a blind, painful eye. The thermal mode at 20 ms and a maximum offset between aiming and therapeutic beams were kept constant. Variable parameters evaluated were energy levels between 2 and 8 J and distance from the limbus of 0.5-3.0 mm. Because of the underlying distortion in three of the eyes, meaningful interpretation by light microscopic evaluation was possible only in the other two. This suggested that the early histologic hallmark of the procedure is similar to that previously observed in human autopsy eyes with ciliary epithelial damage and elevation from underlying tissue. In addition, fibrin and scant inflammatory cells were seen in the space between ciliary epithelium and stroma. Minimal damage was observed in the ciliary muscle. These findings suggest that direct damage to the ciliary epithelium is the most likely mechanism of reduced aqueous production by this cyclodestructive procedure. The findings also support the concept that an anterior placement of approximately 1.0-1.5 mm posterior to the limbus is most likely to damage the ciliary epithelium of the pars plicata.

  1. Phase equilibria in the neodymium-cadmium binary system.

    PubMed

    Skołyszewska-Kühberger, Barbara; Reichmann, Thomas L; Ipser, Herbert

    2014-09-05

    The equilibrium phase diagram of the neodymium-cadmium system has been established by thermal, metallographic and X-ray analysis based on a study of 70 alloys. The system contains three congruently melting intermetallic compounds, i.e. NdCd (1040 °C), NdCd2 (995 °C), Nd11Cd45 (855 °C), and four incongruently melting compounds NdCd3 (860 °C), Nd13Cd58 (740 °C), NdCd6 (655 °C) and NdCd11 (520 °C). Four eutectic reactions are found in this binary system, i.e. at ∼25 at.% Cd and 770 °C, at 58 at.% Cd and 955 °C, at 79 at.% Cd and 850 °C, and very close to pure Cd at 318 °C, as well as one eutectoid reaction at ∼15 at.% Cd and 500 °C. The solid solubility of Nd in Cd is negligible. Dilatometric curves were recorded for three Nd-Cd compositions up to 4 at.% Cd, to accurately determine phase transitions between the solid solutions of Cd in the low- and high-temperature modification of Nd.

  2. Identification of Neodymium in the Apogee H-Band Spectra

    NASA Astrophysics Data System (ADS)

    Hasselquist, Sten; Shetrone, Matthew; Cunha, Katia; Smith, Verne V.; Holtzman, Jon; Lawler, J. E.; Allende Prieto, Carlos; Beers, Timothy C.; Chojnowski, Drew; Fernández-Trincado, J. G.; García-Hernández, D. A.; Hearty, Fred R.; Majewski, Steven R.; Pereira, C. B.; Placco, Vinicius M.; Villanova, Sandro; Zamora, Olga

    2016-12-01

    We present the detection of 10 lines of singly ionized neodymium (Nd ii, Z = 60) in H-band spectra using observations from the SDSS-III Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey. These lines were detected in a metal-poor ([Fe/H] ˜ -1.5), neutron-capture element-enhanced star recently discovered in the APOGEE sample. Using an optical high-resolution spectrum, we derive a Nd abundance for this star using Nd ii lines with precise, laboratory-derived gf values. This optical abundance is used to derive log(gf) values for the H-band lines. We use these lines to rederive Nd ii abundances for two more metal-rich, s-process enhanced stars observed by APOGEE and find that these lines yield consistent Nd ii abundances, confirming the Nd enhancement of these stars. We explore the region of parameter space in the APOGEE sample over which these lines can be used to measure Nd ii abundances. We find that Nd abundances can be reliably derived for ˜18% of the red giants observed by APOGEE. This will result in ˜50,000 Milky Way stars with Nd ii abundances following the conclusion of APOGEE-2, allowing for studies of neutron-capture element abundance distributions across the entire Milky Way.

  3. Transendoscopic neodymium:yttrium aluminum garnet laser irradiation in horses.

    PubMed

    Tate, L P; Sweeney, C L; Cullen, J M; Corbett, W T; Newman, H C; Brown, T C; Ketner, M T

    1989-05-01

    A neodymium:yttrium aluminum garnet (Nd:YAG) laser was used to study effects of applying laser irradiation transendoscopically to the corniculate process of the arytenoid cartilage in horses. Dosimetry was established initially in vitro in 10 corniculate cartilages that were irradiated and examined histologically to determine penetration depths at selected power settings. Eleven horses were given xylazine IV and butorphoral tartrate IV, and their left ventricle and corniculate process were irradiated. Six horses had left laryngeal hemiplegia and were euthanatized and necropsied 14 weeks after laser application and evaluation for upper airway stridor. Endoscopy was performed in the 5 other horses; they were euthanatized and necropsied at selected intervals to characterize the healing process. Healing was by second intention and was complete at 14 weeks. Two horses developed buds of granulation tissue along the laser incision, which resolved after a second laser application. Scar tissue formation resulted in left of midline displacement of the dorsal portion of the right corniculate process. The left ventricle healed without complications and was totally ablated. All horses had inspiratory stridor when exercised 14 weeks after laser irradiation.

  4. Power neodymium-glass amplifier of a repetitively pulsed laser

    NASA Astrophysics Data System (ADS)

    Vinogradov, Aleksandr V.; Gaganov, V. E.; Garanin, Sergey G.; Zhidkov, N. V.; Krotov, V. A.; Martynenko, S. P.; Pozdnyakov, E. V.; Solomatin, I. I.

    2011-11-01

    A neodymium-glass diode-pumped amplifier with a zigzag laser beam propagation through the active medium was elaborated; the amplifier is intended for operation in a repetitively pulsed laser. An amplifier unit with an aperture of 20 × 25 mm and a ~40-cm long active medium was put to a test. The energy of pump radiation amounts to 140 J at a wavelength of 806 nm for a pump duration of 550 μs. The energy parameters of the amplifier were experimentally determined: the small-signal gain per pass ~3.2, the linear gain ~0.031 cm-1 with a nonuniformity of its distribution over the aperture within 15%, the stored energy of 0.16 — 0.21 J cm-3. The wavefront distortions in the zigzag laser-beam propagation through the active element of the amplifier did not exceed 0.4λ (λ = 0.63 μm is the probing radiation wavelength).

  5. Dielectric and impedance spectroscopic studies of neodymium gallate

    NASA Astrophysics Data System (ADS)

    Sakhya, Anup Pradhan; Dutta, Alo; Sinha, T. P.

    2016-05-01

    The AC electrical properties of a polycrystalline neodymium gallate, NdGaO3 (NGO), synthesized by the sol-gel method have been investigated by employing impedance spectroscopy in the frequency range from 42 Hz to 5 MHz and in the temperature range from 323 K to 593 K. The X-ray diffraction analysis shows that the compound crystallizes in the orthorhombic phase with Pbnm space group at room temperature. Two relaxation processes with different relaxation times are observed from the impedance as well as modulus spectroscopic measurements, which have been attributed to the grain and the grain boundary effects at different temperatures in NGO. The complex impedance data are analyzed by an electrical equivalent circuit consisting of a resistance and a constant phase element in parallel. It has been observed that the value of the capacitance and the resistance associated with the grain boundary is higher than those associated with the grain. The temperature dependent electrical conductivity shows the negative temperature coefficient of resistance. The frequency dependent conductivity spectra are found to follow the power law.

  6. Accidental macular hole following neodymium:YAG posterior capsulotomy.

    PubMed

    Munteanu, Mihnea; Petrović, Zarko; Stanca, Horia; Rosca, Cosmin; Jianu, Adelina; Boruga, Ovidiu

    2014-01-01

    Posterior capsular opacification (PCO) is the commonest complication of cataract surgery, occurring in up to one-third of patients in a period of five years. The treatment of choice is the Neodymium:YAG laser posterior capsulotomy. This treatment can be associated with several complications, some of them severe. A rare complication of this procedure is the accidental induced macular hole. A 54-year-old female patient was referred to our Department because of a severe loss of vision and a central scotoma at the right eye. The patient underwent a Nd:YAG posterior capsulotomy 2 days ago, for a PCO. The fundus examination at presentation revealed a round retinal defect in the macular region, a massive inferior preretinal hemorrhage and a mild vitreous hamorrhage. A 6-months follow-up of the case, including retinography and fluorescein angiography, is presented. Although the Nd:YAG laser capsulotomy is a safe, noninvasive, and effective outpatient procedure to improve vision hindered by PCO, it must be recognized that it carries a low but definite risk of serious complications. Physicians and patients should be aware of these rare but severe complications regarding this otherwise safe procedure. Fortunately, most of the complications related to this procedure are transient and can be managed by proper medication.

  7. Dielectric and impedance behavior of neodymium substituted strontium hexaferrite

    NASA Astrophysics Data System (ADS)

    Bhat, Bilal Hamid; Samad, Rubiya; Want, Basharat

    2016-09-01

    In this study, dielectric behavior and complex impedance of neodymium (Nd) substituted strontium hexaferrite system: Sr1- x Nd x Fe12O19 ( x = 0.0, 0.05, 0.1, 0.15, 0. 20), synthesized by citrate precursor technique, have been evaluated as a function of applied frequency and temperature. Variation of dielectric constant and dielectric loss with frequency shows the identical behavior for all the compositions. The value of dielectric constant increases with Nd doping. Relaxation process is observed in the composition x = 0.20, and the peaks in this composition shift toward the higher-frequency region as the temperature increases. The dielectric constants show temperature-independent behavior at low temperature, whereas at higher temperatures it increases for all the frequencies. The AC conductivity follows Jonscher's power law, showing that conduction mechanism is due to polaron hopping. Complex impedance as a function of composition and temperature is used to examine the role of grain and grain boundary in the prepared material. Cole-cole plot shows only one semicircle up to x = 0.15, while as for x = 0.20 two semicircles are observed. The conduction mechanism is explained on the basis of both grain and grain boundary.

  8. Laboratory and clinical experience with neodymium:YAG laser prostatectomy

    NASA Astrophysics Data System (ADS)

    Kabalin, John N.

    1996-05-01

    Since 1991, we have undertaken extensive laboratory and clinical studies of the Neodymium:YAG (Nd:YAG) laser for surgical treatment of bladder outlet obstruction due to prostatic enlargement or benign prostatic hyperplasia (BPH). Side-firing optical fibers which emit a divergent, relatively low energy density Nd:YAG laser beam produce coagulation necrosis of obstructing periurethral prostate tissue, followed by gradual dissolution and slough in the urinary stream. Laser-tissue interactions and Nd:YAG laser dosimetry for prostatectomy have been studied in canine and human prostate model systems, enhancing clinical application. Ongoing studies examine comparative Nd:YAG laser dosimetry for various beam configurations produced by available side-firing optical fibers and continue to refine operative technique. We have documented clinical outcomes of Nd:YAG laser prostatectomy in 230 consecutive patients treated with the UrolaseTM side-firing optical fiber. Nd:YAG laser coagulation the prostate produces a remarkably low acute morbidity profile, with no significant bleeding or fluid absorption. No postoperative incontinence has been produced. Serial assessments of voiding outcomes over more than 3 years of followup show objective and symptomatic improvement following Nd:YAG laser prostatectomy which is comparable to older but more morbid electrosurgical approaches. Nd:YAG laser prostatectomy is a safe, efficacious, durable and cost-effective treatment for BPH.

  9. Amended Silicated for Mercury Control

    SciTech Connect

    James Butz; Thomas Broderick; Craig Turchi

    2006-12-31

    Amended Silicates{trademark}, a powdered, noncarbon mercury-control sorbent, was tested at Duke Energy's Miami Fort Station, Unit 6 during the first quarter of 2006. Unit 6 is a 175-MW boiler with a cold-side electrostatic precipitator (ESP). The plant burns run-of-the-river eastern bituminous coal with typical ash contents ranging from 8-15% and sulfur contents from 1.6-2.6% on an as-received basis. The performance of the Amended Silicates sorbent was compared with that for powdered activated carbon (PAC). The trial began with a period of baseline monitoring during which no sorbent was injected. Sampling during this and subsequent periods indicated mercury capture by the native fly ash was less than 10%. After the baseline period, Amended Silicates sorbent was injected at several different ratios, followed by a 30-day trial at a fixed injection ratio of 5-6 lb/MMACF. After this period, PAC was injected to provide a comparison. Approximately 40% mercury control was achieved for both the Amended Silicates sorbent and PAC at injection ratios of 5-6 lbs/MMACF. Higher injection ratios did not achieve significantly increased removal. Similar removal efficiencies have been reported for PAC injection trials at other plants with cold-side ESPs, most notably for plants using medium to high sulfur coal. Sorbent injection did not detrimentally impact plant operations and testing confirmed that the use of Amended Silicates sorbent does not degrade fly ash quality (unlike PAC). The cost for mercury control using either PAC or Amended Silicates sorbent was estimated to be equivalent if fly ash sales are not a consideration. However, if the plant did sell fly ash, the effective cost for mercury control could more than double if those sales were no longer possible, due to lost by-product sales and additional cost for waste disposal. Accordingly, the use of Amended Silicates sorbent could reduce the overall cost of mercury control by 50% or more versus PAC for locations where fly

  10. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  11. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  12. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  13. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  14. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  15. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  16. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  17. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  18. 21 CFR 582.2437 - Magnesium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Magnesium silicate. 582.2437 Section 582.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Magnesium silicate. (a) Product. Magnesium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions...

  19. 21 CFR 582.2227 - Calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Calcium silicate. 582.2227 Section 582.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  20. 21 CFR 182.2227 - Calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Calcium silicate. 182.2227 Section 182.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  1. 21 CFR 182.2227 - Calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Calcium silicate. 182.2227 Section 182.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  2. 21 CFR 182.2227 - Calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Calcium silicate. 182.2227 Section 182.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  3. 21 CFR 182.2227 - Calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Calcium silicate. 182.2227 Section 182.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  4. 21 CFR 582.2227 - Calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Calcium silicate. 582.2227 Section 582.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  5. 21 CFR 582.2227 - Calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Calcium silicate. 582.2227 Section 582.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  6. 21 CFR 582.2227 - Calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 582.2227 Section 582.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  7. 21 CFR 582.2227 - Calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium silicate. 582.2227 Section 582.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Calcium silicate. (a) Product. Calcium silicate. (b) Tolerance. 2 percent and 5 percent. (c)...

  8. Effects of ionization on silicate glasses. [Silicate glasses

    SciTech Connect

    Primak, W.

    1982-02-01

    This evaluation of radiation effects in silicate glasses caused by ionization is based on our own investigations, on material collected in our files (reports, articles, and notes), and on a computer literature search through recent issues of Physics Abstracts and Chemical Abstracts (and the apparently pertinent references which appeared). Some of our recent results, available heretofore only in internal correspondence, are presented in some detail. It is concluded that research into the behavior of silicate glasses generally will be required before the specific effects in the radioactive waste storage glasses can be properly understood and evaluated. Two particular neglected areas of investigation are targeted for immediate concern: a kinetic analysis of annealing data and the acquisition of data on effects of irradiation at controlled elevated temperatures.

  9. Electrolytic production of neodymium without perfluorinated carbon compounds on the offgases

    DOEpatents

    Keller, R.; Larimer, K.T.

    1998-09-22

    A method is described for producing neodymium in an electrolytic cell without formation of perfluorinated carbon gases (PFCs), the method comprising the steps of providing an electrolyte in the electrolytic cell and providing an anode in an anode region of the electrolyte and providing a cathode in a cathode region of the electrolytic cell. Dissolving an oxygen-containing neodymium compound in the electrolyte in the anode region and maintaining a more intense electrolyte circulation in the anode region than in the cathode region. Passing an electrolytic current between said anode and said cathode and depositing neodymium metal at the cathode, preventing the formation of perfluorinated carbon gases by limiting anode over voltage. 4 figs.

  10. A Comparison between Two Cell Designs for Electrochemical Neodymium Reduction Using Numerical Simulation

    NASA Astrophysics Data System (ADS)

    Haas, Tim; Hilgendorf, Simon; Vogel, Hanno; Friedrich, Bernd; Pfeifer, Herbert

    2017-08-01

    Nowadays, neodymium is almost solely produced by the electrochemical reduction of Neodymium oxide in fused fluoride salts. Thereby, the fluid flow distribution within the electrolysis cell is important for the productivity and efficiency of the process. In this work, the flow field within a conventional cell with vertical electrodes is compared to that of an innovative cell concept with horizontal electrodes by computational fluid dynamics. The numerical model uses the Eulerian volume of fluid approach to track phase boundaries between the continuous phases, while the Lagrangian discrete phase model is applied to compute the rising trajectories of emitted off-gas bubbles. The calculated results indicate that the new cell type is more suitable for the efficient, large-scale production of neodymium, since there is potential to decrease the cell voltage and enhance the current efficiency. By that, the specific energy consumption can be lowered significantly. However, an advanced level of automation is necessary to operate the new cell.

  11. Lanthanum and neodymium solubility in simplified SiO{sub 2}-B{sub 2}O{sub 3}-Na{sub 2}O-Al{sub 2}O{sub 3}-CaO high level waste glass

    SciTech Connect

    Kidari, Abdessamad; Bardez-Giboire, Isabelle

    2012-08-15

    Lanthanum and neodymium incorporation in simplified high level waste glasses has been investigated for SiO{sub 2}B{sub 2}O{sub 3}Na{sub 2}OAl{sub 2}O{sub 3}CaO compositions quenched from 1200 degrees C, for varying La /(La + Nd) (atomic) and increasing rare-earth oxides contents. In this system and beyond the solubility limit, rare-earths (RE) elements are reported to form apatite phases with the general formula Ca{sub 2}RE{sub 8}(SiO{sub 4}){sub 6}O{sub 2}. In the current study, speciation of these trivalent RE{sup 3+} cations in both amorphous network and crystal phases was determined from X-ray diffraction, scanning electron microscopy, optical absorption at 10 K, Raman spectroscopy, and electron probe microanalysis. It appeared that RE{sub 2}O{sub 3} solubility was higher for La -rich formulations than for Nd -rich ones and that an increase in the RE oxide content reduces the connectivity of the network building units through formation of non-bridging oxygens at the expense of the oxygen bridges. This depolymerization of the glass network did not affect neodymium environment which consisted in silicate tetrahedra. The composition of the apatite crystals was found to be affected by the La /(La + Nd) of the parent glass and deviation from the ideal composition (Ca{sub 2}RE{sub 8}(SiO{sub 4}){sub 6}O{sub 2}) occurred in the neodymium end of the system. It thus appears that both RE{sub 2}O{sub 3} solubility and crystal composition are strongly dependent on the type and crystal chemistry of the RE elements. (authors)

  12. Cometary Silicates: Interstellar and Nebular Materials

    NASA Technical Reports Server (NTRS)

    Wooden, Diane H.

    2002-01-01

    Evidence for interstellar material in comets is deduced from IR spectra, insitu measurements of Halley, and chondritic porous interplanetary dust particles (CP IDPs). IR spectra of comets reveal the spectrally active minerals: amorphous carbon, amorphous silicates, and (in some comets) crystalline silicates. Evidence suggests amorphous silicates are of interstellar origin while crystalline silicates are of nebular origin. 10 microns spectra of comets and submicron amorphous silicate spherules in CP IDPs have shapes similar to lines-of-sight through the ISM. Thermal emission models of cometary IR spectra require Fe-bearing amorphous silicates. Fe-bearing amorphous silicates may be Fe-bearing crystalline silicates formed in AGB outflows that are amorphized through He+ ion bombardment in supernova shocks in the ISM. Crystalline silicates in comets, as revealed by IR spectra, and their apparent absence in the ISM, argues for their nebular origin. The high temperatures (less than l000 K) at which crystals form or are annealed occur in the inner nebula or in nebular shocks in the 5-10 AU region. Oxygen isotope studies of CP IDPs show by mass only 1 % of the silicate crystals are of AGB origin. Together this suggests crystalline silicates in comets are probably primitive grains from the early solar nebula.

  13. Rare earth elements and neodymium isotopes in sedimentary organic matter

    NASA Astrophysics Data System (ADS)

    Freslon, Nicolas; Bayon, Germain; Toucanne, Samuel; Bermell, Sylvain; Bollinger, Claire; Chéron, Sandrine; Etoubleau, Joel; Germain, Yoan; Khripounoff, Alexis; Ponzevera, Emmanuel; Rouget, Marie-Laure

    2014-09-01

    We report rare earth element (REE) and neodymium (Nd) isotope data for the organic fraction of sediments collected from various depositional environments, i.e. rivers (n = 25), estuaries (n = 18), open-ocean settings (n = 15), and cold seeps (n = 12). Sedimentary organic matter (SOM) was extracted using a mixed hydrogen peroxide/nitric acid solution (20%-H2O2-0.02 M-HNO3), after removal of carbonate and oxy-hydroxide phases with dilute hydrochloric acid (0.25 M-HCl). A series of experimental tests indicate that extraction of sedimentary organic compounds using H2O2 may be complicated occasionally by partial dissolution of sulphide minerals and residual carbonates. However, this contamination is expected to be minor for REE because measured concentrations in H2O2 leachates are about two-orders of magnitude higher than in the above mentioned phases. The mean REE concentrations determined in the H2O2 leachates for samples from rivers, estuaries, coastal seas and open-ocean settings yield relatively similar levels, with ΣREE = 109 ± 86 ppm (mean ± s; n = 58). The organic fractions leached from cold seep sediments display even higher concentration levels (285 ± 150 ppm; mean ± s; n = 12). The H2O2 leachates for most sediments exhibit remarkably similar shale-normalized REE patterns, all characterized by a mid-REE enrichment compared to the other REE. This suggests that the distribution of REE in leached sedimentary organic phases is controlled primarily by biogeochemical processes, rather than by the composition of the source from which they derive (e.g. pore, river or sea-water). The Nd isotopic compositions for organic phases leached from river sediments are very similar to those for the corresponding detrital fractions. In contrast, the SOM extracted from marine sediments display εNd values that typically range between the εNd signatures for terrestrial organic matter (inferred from the analysis of the sedimentary detrital fractions) and marine organic matter

  14. 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.

  15. Samarium-neodymium systematics in kimberlites and in the minerals of garnet lherzolite inclusions

    USGS Publications Warehouse

    Basu, A.R.; Tatsumoto, M.

    1979-01-01

    The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 ?? 106 to 1300 ?? 106 years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition. Copyright ?? 1979 AAAS.

  16. Samarium-neodymium systematics in kimberlites and in the minerals of garnet lherzolite inclusions.

    PubMed

    Basu, A R; Tatsumoto, M

    1979-07-27

    The initial ratios of neodymium-143 to neodymium-144 in kimberlites ranging in age between 90 x 10(6) to 1300 x 10(6) years from South Africa, India, and the United States are different from the corresponding ratios in the minerals of peridotite inclusions in the kimberlites but are identical to the ratios in the basaltic achondrite Juvinas at the times of emplacement of the respective kimberlite pipes. This correlation between the kimberlites and Juvinas, which represents the bulk chondritic earth in rare-earth elements, strongly indicates that the kimberlite's source in the mantle is chondritic in rare-earth elements and relatively primeval in composition.

  17. Synthesis of neodymium hydroxide nanotubes and nanorods by soft chemical process.

    PubMed

    Shi, Weidong; Yu, Jiangbo; Wang, Haishui; Yang, Jianhui; Zhang, Hongjie

    2006-08-01

    A facile soft chemical approach using cetyltrimethylammonium bromide (CTAB) as template is successfully designed for synthesis of neodymium hydroxide nanotubes. These nanotubes have an average outer diameter around 20 nm, inner diameter around 2 nm, and length ranging from 100 to 120 nm, high BET surface area of 495.71 m(2) g(-1). We also find that neodymium hydroxide nanorods would be obtained when CTAB absented in reaction system. The Nd(OH)3 nanorods might act as precursors that are converted into Nd2O3 nanorods through dehydration at 550 degrees C. The nanorods could exhibit upconversion emission characteristic under excitation of 591 nm at room temperature.

  18. Preparation of yttrium, lanthanum, cerium, and neodymium basic carbonate particles by homogeneous precipitation

    SciTech Connect

    Akinc, M.; Sordelet, D. )

    1987-07-01

    Uniform yttrium, lanthanum, cerium, and neodymium basic carbonate particles were prepared by homogeneous precipitation. Powders were characterized with respect to size, shape, crystal structure, and thermal decomposition behavior. Yttria precursor particles were spherical, monosized (0.4 {mu}m), and amorphous; whereas lanthana, neodymia, and ceria precursors were prismatic (ranging from 1 to 6 {mu}m in size) and crystalline. Crystal structure was found to be ancylite-type orthorhombic symmetry in all three cases. Upon heating in air, yttrium, lanthanum, and neodymium precursors underwent two-step decomposition to first form oxycarbonate and then oxide. Cerium hydroxycarbonate decomposed in a single step to form the oxide.

  19. Surface characterization of silicate bioceramics.

    PubMed

    Cerruti, Marta

    2012-03-28

    The success of an implanted prosthetic material is determined by the early events occurring at the interface between the material and the body. These events depend on many surface properties, with the main ones including the surface's composition, porosity, roughness, topography, charge, functional groups and exposed area. This review will portray how our understanding of the surface reactivity of silicate bioceramics has emerged and evolved in the past four decades, owing to the adoption of many complementary surface characterization tools. The review is organized in sections dedicated to a specific surface property, each describing how the property influences the body's response to the material, and the tools that have been adopted to analyse it. The final section introduces the techniques that have yet to be applied extensively to silicate bioceramics, and the information that they could provide.

  20. Modifying Silicates for Better Dispersion in Nanocomposites

    NASA Technical Reports Server (NTRS)

    Campbell, Sandi

    2005-01-01

    An improved chemical modification has been developed to enhance the dispersion of layered silicate particles in the formulation of a polymer/silicate nanocomposite material. The modification involves, among other things, the co-exchange of an alkyl ammonium ion and a monoprotonated diamine with interlayer cations of the silicate. The net overall effects of the improved chemical modification are to improve processability of the nanocomposite and maximize the benefits of dispersing the silicate particles into the polymer. Some background discussion is necessary to give meaning to a description of this development. Polymer/silicate nanocomposites are also denoted polymer/clay composites because the silicate particles in them are typically derived from clay particles. Particles of clay comprise layers of silicate platelets separated by gaps called "galleries." The platelet thickness is 1 nm. The length varies from 30 nm to 1 m, depending on the silicate. In order to fully realize the benefits of polymer/silicate nanocomposites, it is necessary to ensure that the platelets become dispersed in the polymer matrices. Proper dispersion can impart physical and chemical properties that make nanocomposites attractive for a variety of applications. In order to achieve nanometer-level dispersion of a layered silicate into a polymer matrix, it is typically necessary to modify the interlayer silicate surfaces by attaching organic functional groups. This modification can be achieved easily by ion exchange between the interlayer metal cations found naturally in the silicate and protonated organic cations - typically protonated amines. Long-chain alkyl ammonium ions are commonly chosen as the ion-exchange materials because they effectively lower the surface energies of the silicates and ease the incorporation of organic monomers or polymers into the silicate galleries. This completes the background discussion. In the present improved modification of the interlayer silicate surfaces

  1. Longevity of silicate ceramic restorations.

    PubMed

    Beier, Ulrike Stephanie; Dumfahrt, Herbert

    2014-09-01

    The demand for esthetic restorations has resulted in an increased use of dental ceramics as a biocompatible and functionally sufficient alternative to conventional restorative materials. Silicate ceramic restorations are widely used for veneers, inlays, onlays, and crowns in dentistry. Long-term data are of crucial importance to optimize clinical practice. The purpose of the present article is to summarize data of the Innsbruck ceramic evaluation up to 261 months with the focus on longevity and failure characteristics.

  2. Properties of Tricalcium Silicate Sealers.

    PubMed

    Khalil, Issam; Naaman, Alfred; Camilleri, Josette

    2016-10-01

    Sealers based on tricalcium silicate cement aim at an interaction of the sealer with the root canal wall, alkalinity with potential antimicrobial activity, and the ability to set in a wet field. The aim of this study was to characterize and investigate the properties of a new tricalcium silicate-based sealer and verify its compliance to ISO 6876 (2012). A new tricalcium silicate-based sealer (Bio MM; St Joseph University, Beirut, Lebanon), BioRoot RCS (Septodont, St Maure de Fosses, France), and AH Plus (Dentsply, DeTrey, Konstanz, Germany) were investigated. Characterization using scanning electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction analysis was performed. Furthermore, sealer setting time, flow, film thickness, and radiopacity were performed following ISO specifications. pH and ion leaching in solution were assessed by pH analysis and inductively coupled plasma. Bio MM and BioRoot RCS were both composed of tricalcium silicate and tantalum oxide in Bio MM and zirconium oxide in BioRoot RCS. In addition, the Bio MM contained calcium carbonate and a phosphate phase. The inorganic components of AH Plus were calcium tungstate and zirconium oxide. AH Plus complied with the ISO norms for both flow and film thickness. BioRoot RCS and Bio MM exhibited a lower flow and a higher film thickness than that specified for sealer cements in ISO 6876. All test sealers exhibited adequate radiopacity. Bio MM interacted with physiologic solution, thus showing potential for bioactivity. Sealer properties were acceptable and comparable with other sealers available clinically. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  3. Sulfide in the core and the composition of the silicate Earth

    NASA Astrophysics Data System (ADS)

    Burton, K. W.

    2015-12-01

    The chemical composition of the Earth is traditionally explained in terms of evolution from a solar-like composition, similar to that found in primitive 'chondritic' meteorites. It now appears, however, that the silicate Earth is not 'chondritic', but depleted in incompatible elements, including refractory lithophile and heat-producing elements. Either Earth lost material during planet-building due to collisional erosion or else internal differentiation processes produced a hidden reservoir deep in the early Earth. Sulfide in the core may provide a reservoir capable of balancing the composition of the silicate Earth. Recent experimental work suggests that the core contains a significant proportion of sulfide, added during the final stages of accretion and new data suggests that at high pressures sulfide can incorporate a substantial amount of refractory lithophile and heat-producing elements [1]. Pioneering work using the short-lived 146Sm-142Nd system strongly suggests that Earth's silicate mantle is non-chondritic [e.g. 2]. The drawback of such radiogenic isotope systems is that it is not possible to distinguish the fractionation of Sm/Nd that occurs during silicate melting from that occurring during the segregation of a sulfide-melt to form the core. Neodymium stable isotopes have the potential to provide just such a tracer of sulfide segregation, because there is a significant contrast in bonding environment between sulfide and silicate, where heavy isotopes should be preferentially incorporated into high force-constant bonds involving REE3+ (i.e. the silicate mantle). Preliminary data indicate that mantle rocks do indeed possess heavier 146Nd/144Nd values than chondritic meteorites, consistent with the removal of light Nd into sulfide in the core, driving the residual mantle to heavy values. Overall, our isotope and elemental data indicate that the rare earths and other incompatible elements are substantially incorporated into sulfide. While Nd Stable isotope

  4. Variability of neodymium isotopes associated with planktonic foraminifera in the Pacific Ocean during the Holocene and Last Glacial Maximum

    NASA Astrophysics Data System (ADS)

    Hu, Rong; Piotrowski, Alexander M.; Bostock, Helen C.; Crowhurst, Simon; Rennie, Victoria

    2016-08-01

    The deep Pacific Ocean holds the largest oceanic reservoir of carbon which may interchange with the atmosphere on climatologically important timescales. The circulation of the deep Pacific during the Last Glacial Maximum (LGM), however, is not well understood. Neodymium (Nd) isotopes of ferromanganese oxide coatings precipitated on planktonic foraminifera are a valuable proxy for deep ocean water mass reconstruction in paleoceanography. In this study, we present Nd isotope compositions (εNd) of planktonic foraminifera for the Holocene and the LGM obtained from 55 new sites widely distributed in the Pacific Ocean. The Holocene planktonic foraminiferal εNd results agree with the proximal seawater data, indicating that they provide a reliable record of modern bottom water Nd isotopes in the deep Pacific. There is a good correlation between foraminiferal εNd and seawater phosphate concentrations (R2 = 0.80), but poorer correlation with silicate (R2 = 0.37). Our interpretation is that the radiogenic Nd isotope is added to the deep open Pacific through particle release from the upper ocean during deep water mass advection and aging. The data thus also imply the Nd isotopes in the Pacific are not likely to be controlled by silicate cycling. In the North Pacific, the glacial Nd isotopic compositions are similar to the Holocene values, indicating that the Nd isotope composition of North Pacific Deep Water (NPDW) remained constant (-3.5 to -4). During the LGM, the southwest Pacific cores throughout the water column show higher εNd corroborating previous studies which suggested a reduced inflow of North Atlantic Deep Water to the Pacific. However, the western equatorial Pacific deep water does not record a corresponding radiogenic excursion, implying reduced radiogenic boundary inputs during the LGM probably due to a shorter duration of seawater-particle interaction in a stronger glacial deep boundary current. A significant negative glacial εNd excursion is evident in

  5. Groundtruthing the Neodymium Isotope Proxy in Deep-Sea Corals

    NASA Astrophysics Data System (ADS)

    van de Flierdt, T.; Robinson, L. F.; Adkins, J. F.

    2007-12-01

    The Nd isotopic composition of marine precipitates is increasingly recognized as a powerful tool in paleoceanography. Unlike nutrient proxies such as δ13C or Cd/Ca, Nd isotopes are not thought to be altered by biological processes, and thus may serve as a quasi-conservative water mass mixing tracer. However, any archive, which is used to extract authigenic Nd isotopes, needs careful examination, to test the integrity of the inferred seawater signal. Here we present first data on cleaning experiments and modern calibration experiments on different species of deep-sea corals. Seven different coral samples ranging in age from modern to ~220ka were selected for experiments designed to remove ferromanganese crusts and / or organic residues that may contain high concentrations of Nd and Th. The aim was to determine whether the rigorous chemical procedure we use to remove Th associated with these crusts is effective at removing Nd, and whether it causes any fractionation in the Nd isotopic composition of the coral aragonite. Crusts were found to contain Th-232 concentrations of up to ~160ppm, with 232Th/230Th ratios dependent on the oceanic location of the coral. Un-cleaned corals had Th-232 concentrations of up to 8ppb and the cleaning procedure reduced these values to less than 0.2ppb in both modern and fossil specimens. Neodymium isotopic compositions reveal that for modern corals, with no visible coating, a pre-cleaning step is sufficient to yield the isotopic composition of ambient seawater. The ferromanganese coating around fossil corals however may have a very different isotopic composition than the coral aragonite since it may be a time-integrated signal biased towards modern values. This bias is observed for intermediate water depth D. dianthus corals from stage 3 in the northwest Atlantic. Modern D. dianthus skeletons from the northwest Atlantic and the Drake Passage reflect the seawater Nd isotopic composition, and we are extending this modern calibration to

  6. Dissolved Neodymium Isotopes and Concentrations in the South Pacific

    NASA Astrophysics Data System (ADS)

    Basak, C.; Pahnke, K.

    2013-12-01

    The isotopic composition of dissolved Neodymium (expressed as ɛNd) in seawater is becoming increasingly established as a tracer for present and past water mass structure and flow paths. The South Pacific represents the largest sector of the Southern Ocean and harbors major areas of bottom and intermediate water mass formation and is therefore a key area for understanding present and past deep ocean circulation. While more dissolved Nd data are becoming available from different ocean basins, the South Pacific is still understudied with respect to the distribution of Nd isotopes and concentrations. In this study we have analyzed dissolved Nd isotopes and concentrations from 11 water column profiles across the South Pacific between 46°S and 69°S that sample all water masses. Our data show that the bottom water in the vicinity of the Ross Sea (Ross Sea Bottom water, RSBW) is represented by an ɛNd value of ~ -7, while the overlying Circumpolar Deep Water (CDW) carries a signature of ɛNd = -8 to -9. The characteristic Nd isotopic signal of RSBW can be tracked along its flow path into the southeast Pacific where it progressively looses its signal through interaction with ambient CDW. The easternmost stations, closer to South America, exhibit an excursion towards radiogenic ɛNd at ≤2000 m water depth. This change towards more positive ɛNd coincides with low oxygen and high phosphate concentrations representing Pacific Deep Water (PDW) and possibly indicates water mass mixing of CDW with more radiogenic PDW. While the Nd isotopic composition shows apparent variations between stations and different water masses, the concentration profiles show a rather uniform and gradual increase with depth, a pattern typical for open ocean settings. Spatial and vertical contrasts in Nd isotopic values throughout the South Pacific indicate that Nd isotopes can be used as a water mass tracer in this region. It is reasonable to infer that local lithology in the Ross Sea influenced

  7. Neodymium YAG (yttrium-aluminum-garnet) lasers. (Latest citations from the Inspec database). Published Search

    SciTech Connect

    1996-02-01

    The bibliography contains citations concerning the properties and applications of neodymium-yttrium-aluminum-garnet (Nd:YAG) lasers. Applications include welding, soldering of printed circuit boards, medical applications, telecommunication systems, rangefinding, and optical pumping of high powered lasers.(Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  8. Demonstrating and Measuring Relative Molar Magnetic Susceptibility Using a Neodymium Magnet

    ERIC Educational Resources Information Center

    Malerich, Charles; Ruff, Patricia K.; Bird, Aubrey

    2004-01-01

    An easy-to-see method for demonstrating and measuring the magnetic force between paramagnetic substance and a rare earth magnet is presented. The readily available trapezoid-shaped neodymium magnet and a low cost, easy-to-set-up, portable apparatus are used in the experiments.

  9. Neodymium as the main feature of permanent magnets from hard disk drives (HDDs).

    PubMed

    München, Daniel Dotto; Veit, Hugo Marcelo

    2017-03-01

    As a way to manage neodymium-iron-boron (NdFeB) magnets wasted in end-of-life hard disk drives (HDDs), a waste characterization is needed prior to a recycling process. Due to their magnetic properties, NdFeB magnets are essential in technological applications nowadays, thus causing an increase in the industrial demand for rare earth metals. However, these metals have a short supply, since they are difficult to obtain from ores, creating a critical market. In this work, a study of the characterization of sintered neodymium-iron-boron magnets was undertaken by qualitatively and quantitatively uncovering the neodymium recovery potential from this type of electronic waste. From the collection and disassembly of hard disk drives, in which the magnet represents less than 3% of the total weight, an efficient demagnetization process was proceeded at 320°C. Then, the magnet was ground and screened for an X-ray diffraction (XRD) analysis, which showed the Nd2Fe14B tetragonal phase as the dominant constituent of the sample. An analysis was also carried out in a scanning electron microscope (SEM) and an inductively coupled plasma optical emission spectrometer (ICP-OES), where the magnet composition showed 21.5wt% of neodymium and 65.1wt% of iron, among other chemicals. This Nd content is higher than the one found in Nd ores, enhancing the recyclability and the importance of waste management.

  10. Neodymium YAG lasers. Citations from the International Aerospace Abstracts data base

    NASA Technical Reports Server (NTRS)

    Mauk, S. C.

    1980-01-01

    Various aspects of neodymium yag lasers are discussed in approximately 267 citations. Laser materials and outputs, laser mode locking; crystal, fiber, and nonlinear optics, optical pumping communications, energy conversion efficiency, and laser applications are covered. Pulsed, continuous wave, solid state, Q switched, infrared, and dye lasers are included.

  11. Mathematical Description and Modeling of the Vibration Isolation Device with Neodymium Compensator Stiffness

    NASA Astrophysics Data System (ADS)

    Gurova, E. G.

    2017-07-01

    In this article a mathematical description of the block diagram of the vibration isolation device with stiffness compensator is given. The vibration isolation system simulation performed with different functional elements, during which operation waveforms obtained with neodymium device compensator of the stiffness. Research & Development is under the scholarship of the President of Russian Federation, order No 184 from 10th of March 2015.

  12. Neodymium-rich precipitate phases in a high-chromium ferritic/martensitic steel

    NASA Astrophysics Data System (ADS)

    Shen, Yinzhong; Zhou, Xiaoling; Shang, Zhongxia

    2016-05-01

    Neodymium being considered as nitride forming element has been used in a design of advanced ferritic/martensitic (FM) steels for fossil fired power plants at service temperatures of 630 °C to 650 °C to effectively improve the creep strength of the steels. To fully understand the characteristics of neodymium precipitates in high-Cr FM steels, precipitate phases in an 11Cr FM steel with 0.03 wt% addition of Nd have been investigated by transmission electron microscopy. Three neodymium phases with a face-centered cubic crystal structure and different composition were observed in the steel. They consisted of neodymium carbonitride with an average lattice parameter of 1.0836 nm, Nd-rich carbonitride mainly containing Mn, and Nd-rich MN nitride mainly containing Mn and Co. Other three Nd-rich and Nd-containing phases, which appear to be Nd-Co-Cr/Nd-rich intermetallic compounds and Cr-Fe-rich nitride containing Nd, were also detected in the steel. Nd-relevant precipitates were found to be minor phases compared with M23C6 and Nb/V/Ta-rich MX phases in the steel. The content of Nd in other precipitate phases was very low. Most of added Nd is considered to be present as solid solution in the matrix of the steel.

  13. Neodymium and hafnium boundary contributions to seawater along the West Antarctic continental margin

    NASA Astrophysics Data System (ADS)

    Rickli, Jörg; Gutjahr, Marcus; Vance, Derek; Fischer-Gödde, Mario; Hillenbrand, Claus-Dieter; Kuhn, Gerhard

    2014-05-01

    Neodymium and hafnium isotopes and elemental concentrations (Sm, Nd, Hf, Zr) have been measured in three water column profiles south of the Antarctic Circumpolar Current in, and to the east of the Ross Sea, in conjunction with five bottom water samples from the Amundsen Sea Embayment.

  14. Neodymium:YAG treatment of interlenticular opacification in a secondary piggyback case.

    PubMed

    Gayton, J L; Van der Karr, M; Sanders, V

    2001-09-01

    Interlenticular opacification (ILO) developed 7 months after secondary acrylic piggyback lens implantation in which the anterior lens was placed in the bag. This resulted in glare and a hyperopic shift. Treating the ILO with the neodymium:YAG laser successfully reduced the glare and corrected the hyperopic shift.

  15. Demonstrating and Measuring Relative Molar Magnetic Susceptibility Using a Neodymium Magnet

    ERIC Educational Resources Information Center

    Malerich, Charles; Ruff, Patricia K.; Bird, Aubrey

    2004-01-01

    An easy-to-see method for demonstrating and measuring the magnetic force between paramagnetic substance and a rare earth magnet is presented. The readily available trapezoid-shaped neodymium magnet and a low cost, easy-to-set-up, portable apparatus are used in the experiments.

  16. Adsorption kinetics of silicic acid on akaganeite.

    PubMed

    Naren, Gaowa; Ohashi, Hironori; Okaue, Yoshihiro; Yokoyama, Takushi

    2013-06-01

    As part of a series of studies on the interaction between ferric ions and silicic acid in the hydrosphere, the adsorption of silicic acid on akaganeite was investigated kinetically at various pH values. The adsorption of silicic acid increased with increasing pH over an initial pH range of 4-11.5. In the kinetic experiment, the Cl(-) was released from akaganeite much faster than silicic acid was adsorbed. From this result, we concluded that chloride ions bound on the surface of akaganeite are released and Fe-OH or Fe-O(-) sites are formed, which then acts as an adsorption site for silicic acid. The uptake mechanism of silicic acid by akaganeite is significantly different from that by schwertmannite, despite the presence of the same tunnel structure.

  17. Praseodymium Nitrate and Neodymium Complexation with Organophosphorus Reagents in Supercritical Carbon Dioxide Solvent

    SciTech Connect

    Robert V. Fox; R. Duane Ball; Peter de B. Harrington; Harry W. Rollins; John G. Jolley; Chien M. Wai

    2004-11-01

    Complex formation reactions of praseodymium nitrate hexahydrate, and neodymium nitrate hexahydrate salts with tri-n-butyl phosphate (TBP) and several other neutral organophosphorus reagents were investigated in supercritical carbon dioxide. The concentration of the metal complexes in the supercritical fluid (SCF) phase was determined using UV-Vis and luminescence spectroscopies. The stoichiometry of the complexes was determined using the mole-ratio method. Extraction equilibrium constants were calculated from the spectral data using least-squares regression and hard-equilibria models. UV-Vis absorbance data indicate that praseodymium nitrate and neodymium nitrate both form 1:4 lanthanide–tributyl phosphate complexes in supercritical carbon dioxide at 308 K. The conditional extraction coefficients for those two systems were calculated to be log Kex=7.45±0.06 for the praseodymium system and log Kex=7.52±0.03 for the neodymium system. For comparison, neodymium nitrate complexation reactions with tri-n-butyl phosphate and tributyl phosphite (TBPO3) were studied in hexane under ambient conditions. UV-Vis data indicate that a 1:4 neodymium–tributyl phosphate complex is formed in hexane with a conditional extraction coefficient of log Kex=3.4±0.2. Tributyl phosphite forms a 1:8 complex with neodymium in hexane with a conditional extraction coefficient of log Kex=11.0±0.1. Neodymium nitrate was titrated with other organophosphorus reagents, tributyl phosphite and tributyl phosphine oxide (TBPO), in supercritical carbon dioxide to investigate differences between neutral oxygen donor ligands and neutral phosphorus donor ligands. UV-Vis and luminescence data indicate that neodymium nitrate forms a 1:8 complex with tributyl phosphite and a 1:5 complex with tributyl phosphine oxide, compared to a 1:4 complex with tri-n-butyl phosphate. The conditional extraction coefficient for the 1:8 neodymium–tributyl phosphite system was calculated as log Kex=21.4±0.2 from UV

  18. Silicate stabilization studies in propylene glycol

    SciTech Connect

    Schwartz, S.A.

    1999-08-01

    In most North American and many European coolant formulations, the corrosion inhibition of heat-rejecting aluminum surfaces is provided by alkali metal silicates. But, their tendency towards polymerization, leading to gelation and/or precipitation, can reduce the effectiveness of a coolant. This paper presents the results of experiments which illustrate formulation-dependent behavior of inorganic silicate in propylene glycol compositions. Specific examples of the effects of glycol matrix, stabilizer type, and hard water on silicate stabilization are provided.

  19. Cumulate Fragments in Silicic Ignimbrites

    NASA Astrophysics Data System (ADS)

    Bachmann, O.; Ellis, B. S.; Wolff, J.

    2014-12-01

    Increasingly, studies are concluding that silicic ignimbrites are the result of the amalgamation of multiple discrete magma batches. Yet the existence of discrete batches presents a conundrum for magma generation and storage; if silicic magma batches are not generated nearly in situ in the upper crust, they must traverse, and reside within, a thermally hostile environment with large temperature gradients, resulting in low survivability in their shallow magmatic hearths. The Snake River Plain (Idaho, USA) is a type example of this 'multi-batch' assembly with ignimbrites containing multiple populations of pyroxene crystals, glass shards, and crystal aggregates. The ubiquitous crystal aggregates hint at a mechanism to facilitate the existence of multiple, relatively small batches of rhyolite in the upper crust. These aggregates contain the same plagioclase, pyroxene, and oxide mineral compositions as single phenocrysts of the same minerals in their host rocks, but they have significantly less silicic bulk compositions and lack quartz and sanidine, which occur as single phenocrysts in the deposits. This implies significant crystallization followed by melt extraction from mushy reservoir margins. The extracted melt then continues to evolve (crystallizing sanidine and quartz) while the melt-depleted margins provide an increasingly rigid and refractory network segregating the crystal-poor batches of magma. The hot, refractory, margins insulate the crystal-poor lenses, allowing (1) extended residence in the upper crust, and (2) preservation of chemical heterogeneities among batches. In contrast, systems that produce cumulates richer in low-temperature phases (quartz, K-feldspars, and/or biotite) favour remelting upon recharge, leading to less segregation of eruptible melt pockets and the formation of gradationally zoned ignimbrites. The occurrence of similar crystal aggregates from a variety of magmatic lineages suggests the generality of this process.

  20. Mechanisms of magma generation beneath hawaii and mid-ocean ridges: uranium/thorium and samarium/neodymium isotopic evidence.

    PubMed

    Sims, K W; Depaolo, D J; Murrell, M T; Baldridge, W S; Goldstein, S J; Clague, D A

    1995-01-27

    Measurements of uranium/thorium and samarium/neodymium isotopes and concentrations in a suite of Hawaiian basalts show that uranium/thorium fractionation varies systematically with samarium/neodymium fractionation and major-element composition; these correlations can be understood in terms of simple batch melting models with a garnet-bearing peridotite magma source and melt fractions of 0.25 to 6.5 percent. Midocean ridge basalts shows a systematic but much different relation between uranium/thorium fractionation and samarium/neodymium fractionation, which, although broadly consistent with melting of a garnet-bearing peridotite source, requires a more complex melting model.

  1. A review of bioactive silicate ceramics.

    PubMed

    Wu, Chengtie; Chang, Jiang

    2013-06-01

    Silicate bioceramics, as a new family of biomaterials, have received significant attention in their application to hard tissue regeneration. Some silicate bioceramics have shown excellent apatite mineralization in simulated body fluids and their ionic products have been shown to enhance the proliferation, osteogenic differentiation and gene expression of stem cells. In this paper, we review the advances in the research of silicate system bioceramics, including preparation methods, mechanical strength, apatite mineralization, dissolution and in vitro and in vivo biological properties. The biological properties and the corresponding mechanism have been highlighted. A look forward to the application of silicate bioceramics to bone regeneration is further suggested.

  2. Tailoring polymer properties with layered silicates

    NASA Astrophysics Data System (ADS)

    Xu, Liang

    Polymer layered silicate nanocomposites have found widespread applications in areas such as plastics, oil and gas production, biomedical, automotive and information storage, but their successful commercialization critically depends on consistent control over issues such as complete dispersion of layered silicate into the host polymer and optimal interaction between the layered silicates and the polymers. Polypropylene is a commercially important polymer but usually forms intercalated structures with organically modified layered silicate upon mixing, even it is pre-treated with compatibilizing agent such as maleic anhydride. In this work, layered silicate is well dispersed in ammonium modified polypropylene but does not provide sufficient reinforcement to the host polymer due to poor interactions. On the other hand, interactions between maleic anhydride modified polypropylene and layered silicate are fine tuned by using a small amount of maleic anhydride and mechanical strength of the resultant nanocomposites are significantly enhanced. In particular, the melt rheological properties of layered silicate nanocomposites with maleic anhydride functionalized polypropylene are contrasted to those based on ammonium-terminated polypropylene. While the maleic anhydride treated polypropylene based nanocomposites exhibit solid-like linear dynamic behavior, consistent with the formation of a long-lived percolated nanoparticle network, the single-end ammonium functionalized polypropylene based nanocomposites demonstrated liquid-like behavior at comparable montmorillonite concentrations. The differences in the linear viscoelasticity are attributed to the presence of bridging interaction in maleic anhydride functionalized nanocomposites, which facilitates formation of a long-lived silicate network mediated by physisorbed polymer chains. Further, the transient shear stress of the maleic anhydride functionalized nanocomposites in start-up of steady shear is a function of the shear

  3. Basaltic injections into floored silicic magma chambers

    NASA Astrophysics Data System (ADS)

    Wiebe, R. A.

    Recent studies have provided compelling evidence that many large accumulations of silicic volcanic rocks erupted from long-lasting, floored chambers of silicic magma that were repeatedly injected by basaltic magma. These basaltic infusions are commonly thought to play an important role in the evolution of the silicic systems: they have been proposed as a cause for explosive silicic eruptions [Sparks and Sigurdsson, 1977], compositional variation in ash-flow sheets [Smith, 1979], mafic magmatic inclusions in silicic volcanic rocks [Bacon, 1986], and mixing of mafic and silicic magmas [Anderson, 1976; Eichelberger, 1978]. If, as seems likely, floored silicic magma chambers have frequently been invaded by basalt, then plutonic bodies should provide records of these events. Although plutonic evidence for mixing and commingling of mafic and silicic magmas has been recognized for many years, it has been established only recently that some intrusive complex originated through multiple basaltic injections into floored chambers of silicic magma [e.g., Wiebe, 1974; Michael, 1991; Chapman and Rhodes, 1992].

  4. Sulfide in the core and the Nd isotopic composition of the silicate Earth

    NASA Astrophysics Data System (ADS)

    McCoy-West, A.; Millet, M. A.; Nowell, G. M.; Wohlers, A.; Wood, B. J.; Burton, K. W.

    2016-12-01

    The chemical composition of the Earth is traditionally explained in terms of evolution from a solar-like composition, similar to that found in primitive chondritic meteorites. It now appears, however, that the silicate Earth is not chondritic, but depleted in incompatible elements and a resovable 20 ppm excess is observed in 142Nd relative to chondirtes [1, 2]. This anomaly requires a process that occurred within 30 Myr of solar system formation and has been variably ascribed to: a complementary enriched reservoir in the deep Earth [1]; loss to space through collisional erosion [3]; or the inhertence of nucleosynthetic anomalies [4]. Sulfide in the core may provide a reservoir capable of balancing the composition of the silicate Earth. Recent experimental work suggests that the core contains a significant proportion of sulfide, added during the final stages of accretion and new data suggests that at high pressures sulfide can incorporate a substantial amount of refractory lithophile and heat-producing elements [5]. The drawback of the short-lived 146Sm-142Nd radiogenic isotope system is that it is not possible to distinguish between fractionations of Sm/Nd that occurs during silicate melting or segregation of a sulfide-melt. Neodymium stable isotopes have the potential to provide just such a tracer of sulfide segregation, because there is a significant contrast in bonding environment between sulfide and silicate, where heavy isotopes should be preferentially incorporated into high force-constant bonds involving REE3+ (i.e. the silicate mantle). Preliminary data indicate that mantle rocks do indeed possess heavier 146Nd/144Nd values than chondritic meteorites by 0.3 ‰, consistent with the removal of light Nd into sulfide in the core, driving the residual mantle to heavier values. Overall, our isotope and elemental data indicate that the rare earths and other incompatible elements are substantially incorporated into sulfide. While Nd stable isotope data for

  5. Nanoscale zinc silicate from phytoliths

    NASA Astrophysics Data System (ADS)

    Qadri, S. B.; Gorzkowski, E. P.; Rath, B. B.; Feng, C. R.; Amarasinghe, R.; Freitas, J. A.; Culbertson, J. C.; Wollmershauser, J. A.

    2017-10-01

    We report a faster, less expensive method of producing zinc silicate nanoparticles. Such particles are used in high volume to make phosphors and anti-corrosion coatings. The approach makes use of phytoliths (plant rocks), which are microscopic, amorphous, and largely silicate particles embedded in plants, that lend themselves to being easily broken down into nanoparticles. Nanoparticles of Zn2SiO4 were produced in a two stage process. In the refinement stage, plant residue, mixed with an appropriate amount of ZnO, was heated in an argon atmosphere to a temperature exceeding 1400 °C for four to six hours and then heated in air at 650 °C to remove excess carbon. TEM shows 50-100 nm nanoparticles. Raman scattering indicates that only the -Zn2SiO4 crystalline phase was present. X-ray analysis indicated pure rhombohedral R 3 bar phase results from using rice/wheat husks. Both samples luminesced predominantly at 523 nm when illuminated with X-rays or UV laser light.

  6. Fingerprinting Northeast Atlantic water masses using neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Dubois-Dauphin, Quentin; Colin, Christophe; Bonneau, Lucile; Montagna, Paolo; Wu, Qiong; Van Rooij, David; Reverdin, Gilles; Douville, Eric; Thil, François; Waldner, Astrid; Frank, Norbert

    2017-08-01

    Dissolved neodymium (Nd) isotopic composition (expressed as εNd) has been analysed for 82 seawater samples collected from 13 stations stretching from the Alboran Sea to the Iceland Basin. The distribution of the εNd values of water masses was thus investigated for the first time along the western European margin in order to explore whether the water masses flowing in the eastern subpolar and subtropical Atlantic reveal distinct isotopic patterns. The Modified Atlantic Water (MAW) in the Alboran Sea displays εNd values (between -9.2 ± 0.2 and -8.9 ± 0.2) that are significantly more radiogenic than those reported in previous studies (-10.8 ± 0.2 to -9.7 ± 0.2), suggesting temporal variations in the Nd isotopic composition of the water that enters the Mediterranean Sea from the Strait of Gibraltar. The εNd value of the underlying modified Winter Intermediate Water (WIW) has been established for the first time (-9.8 ± 0.3) and is compatible with a Nd signature acquired from the sinking of MAW in the northwestern Mediterranean Sea. Within the Gulf of Cádiz, southern Mediterranean Sea Water (MSW) (-10.6 ± 0.2) differs slightly from the northern MSW (-9.9 ± 0.4) owing to a significant contribution of modified East Antarctic Intermediate Water (EAAIW) (-10.9 ± 0.2). In the northeast Atlantic, the North Atlantic Current surface water located in the inter-gyre region (north of 46°N) displays εNd values of between -14.0 ± 0.3 and -15.1 ± 0.3, reflecting the subpolar gyre signature. Along the western European margin, εNd values of surface water decrease toward the north (from -10.4 ± 1.6 to -13.7 ± 1.0) in agreement with the gradual mixing between subtropical and subpolar water. At intermediate depth, εNd values decrease from -9.9 ± 0.4 within the Gulf of Cádiz to -12.1 ± 0.2 within the Porcupine Seabight, indicating a strong dilution of the MSW with subpolar water. Within the Rockall Trough and the Iceland Basin, the more negative εNd values at mid

  7. 21 CFR 182.2437 - Magnesium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Magnesium silicate. 182.2437 Section 182.2437 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2437 Magnesium silicate. (a) Product. Magnesium...

  8. 21 CFR 182.2227 - Calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Calcium silicate. 182.2227 Section 182.2227 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2227 Calcium silicate. (a) Product. Calcium...

  9. Preparation of transparent neodymium-doped yttrium aluminate garnet (Nd:YAG) ceramics with the use of freeze granulation

    NASA Astrophysics Data System (ADS)

    Wajler, Anna; Węglarz, Helena; Sidorowicz, Agata; Zych, Łukasz; Nakielska, Magdalena; Jach, Katarzyna; Tomaszewski, Henryk

    2015-12-01

    This paper presents the results of the application of freeze granulation to the production of transparent neodymium-doped yttrium-aluminum garnet ceramics. Aqueous suspensions of aluminium oxide, yttrium oxide and neodymium oxide powders were prepared based on nanometric or submicronic powders which were either commercially available or prepared by precipitation. The relations between the composition of suspension, the properties of granulate and the final properties of ceramics (microstructure, optical transmission and emission spectra) were studied.

  10. Comparison of sutureless argon- and neodymium:YAG-welded ileo-ileal anastomosis using a biodegradable intraluminal stent

    NASA Astrophysics Data System (ADS)

    Costello, Anthony J.; Johnson, Douglas E.; Wishnow, Kenneth I.

    1990-06-01

    Sutureless end-to-end ileo-ileal intestinal anastomoses were successfully constructed with both the 1.06 jim neodymium:YAG and the 488/515-nm argon lasers. A 5-watt power setting was used with the neodymium:YAG, and various biologic solutions were added to the anastomotic seam during lasing. Power settings of 1.5, 3, 4, and 5 watts were used for argon lasing, with and without an exogenous chromophore. At the 4-watt argon setting, a continuous infusion of normal saline was dripped onto the anastomosis during lasing, replacing the chromophore. All bowel anastomoses were constructed with the aid of a biodegradable intraluminal stent that held the bowel ends in place during construction of the watertight ileal fusion and then completely degraded within 8 hours. We concluded that the neodymium:YAG seemed superior for tissue fusion using the techniques outlined, as it was associated with fewer anastomotic leaks. It appeared easier to determine the end-point of tissue fusion with the neodymium:YAG than the argon, because the tissue changes were more obvious during neodymium:YAG lasing. The deeper penetration into the bowel wall of neodymium:YAG laser energy may confer a welding advantage over the more shallow penetration of the argon wavelength.

  11. Mesoporous Silicate Materials in Sensing

    PubMed Central

    Melde, Brian J.; Johnson, Brandy J.; Charles, Paul T.

    2008-01-01

    Mesoporous silicas, especially those exhibiting ordered pore systems and uniform pore diameters, have shown great potential for sensing applications in recent years. Morphological control grants them versatility in the method of deployment whether as bulk powders, monoliths, thin films, or embedded in coatings. High surface areas and pore sizes greater than 2 nm make them effective as adsorbent coatings for humidity sensors. The pore networks also provide the potential for immobilization of enzymes within the materials. Functionalization of materials by silane grafting or through co-condensation of silicate precursors can be used to provide mesoporous materials with a variety of fluorescent probes as well as surface properties that aid in selective detection of specific analytes. This review will illustrate how mesoporous silicas have been applied to sensing changes in relative humidity, changes in pH, metal cations, toxic industrial compounds, volatile organic compounds, small molecules and ions, nitroenergetic compounds, and biologically relevant molecules. PMID:27873810

  12. Photocatalytic treatment of municipal wastewater using modified neodymium doped TiO(2) hybrid nanoparticles.

    PubMed

    Shahmoradi, Behzad; Ibrahim, Ibrahim A; Sakamoto, Naonori; Ananda, Sannaiah; Somashekar, Rudrappa; Row, Tagur N Guru; Byrappa, Kullaiah

    2010-08-01

    Photocatalytic degradation of municipal wastewater was investigated using reagent grade TiO(2) and modified neodymium doped TiO(2) hybrid nanoparticles. For the first time, surface modification of Nd(3 +) doped TiO(2) hybrid nanoparticles were carried out with n-butylamine as surface modifier under mild hydrothermal conditions. The modified nanoparticles obtained were characterized by Powder XRD, FTIR, DLS, TEM, BET surface area, zeta potential and UV-Vis Spectroscopy. The characterization results indicated better morphology, particle size distribution and low agglomeration of the nanoparticles synthesized. It was found that photodegradation of wastewater using surface modified neodymium doped TiO(2) nanoparticles was more compared to pure TiO(2), which can be attributed to the doping and modification with n-butylamine.

  13. Determination of some heavy metals by flame atomic absorption spectrometry before coprecipitation with neodymium hydroxide.

    PubMed

    Soylak, Mustafa; Kizil, Nebiye

    2011-01-01

    A procedure is described for the determination of trace amounts of Cd(II), Ni(II), Cu(II), Pb(II), Fe(III), Co(II), and Mn(II) that combines flame atomic absorption spectrometry with neodymium hydroxide coprecipitation. The influences of analytical parameters (amount of neodymium, pH of the model solutions, etc.) that affect quantitative recoveries of the analyte ions were investigated. The effects of concomitant ions were also examined. The detection limits for analytes were found in the range of 0.2-3.3 microg/L. The validation of the presented procedure was controlled by analysis of certified reference materials (National Institute of Standards and Technology 1570a spinach leaves and TMDA 54.4 fortified lake water). The applications of the procedure were performed by the analysis of water, food, and herbal plants from Turkey.

  14. Stabilization of neodymium oxide nanoparticles via soft adsorption of charged polymers.

    PubMed

    Dorris, Annie; Sicard, Clémence; Chen, Mark C; McDonald, Arthur B; Barrett, Christopher J

    2011-09-01

    In this work, two synthetic polyelectrolytes, PSS and PAH, are employed as strong adsorbed surfactants to disperse and stabilize neodymium oxide nanoparticles. The acid-base equilibria of the oxide surfaces of the particles were investigated under different pH conditions in the absence and presence of polyelectrolytes, to optimize particle stabilization through enhancement of the effective repulsive surface charges. Surface charge amplification of a 3:5 ratio was achieved to permit improved particle transparency of 100-fold in visible wavelengths in neutral and acidic pH regimes, and a stable 10-fold surface charge amplification was achieved under basic pH conditions. The potential of polyelectrolytes as stabilizing agents for neodymium oxide NPs in large-scale particle physics experiments requiring extremely high optical transparency over long path length is evaluated based on optical absorbance and particle stability.

  15. Neodymium-doped nanoparticles for infrared fluorescence bioimaging: The role of the host

    SciTech Connect

    Rosal, Blanca del; Pérez-Delgado, Alberto; Rocha, Ueslen; Martín Rodríguez, Emma; Jaque, Daniel; Misiak, Małgorzata; Bednarkiewicz, Artur; Vanetsev, Alexander S.; Orlovskii, Yurii; Jovanović, Dragana J.; Dramićanin, Miroslav D.; Upendra Kumar, K.; Jacinto, Carlos; Navarro, Elizabeth; and others

    2015-10-14

    The spectroscopic properties of different infrared-emitting neodymium-doped nanoparticles (LaF{sub 3}:Nd{sup 3+}, SrF{sub 2}:Nd{sup 3+}, NaGdF{sub 4}: Nd{sup 3+}, NaYF{sub 4}: Nd{sup 3+}, KYF{sub 4}: Nd{sup 3+}, GdVO{sub 4}: Nd{sup 3+}, and Nd:YAG) have been systematically analyzed. A comparison of the spectral shapes of both emission and absorption spectra is presented, from which the relevant role played by the host matrix is evidenced. The lack of a “universal” optimum system for infrared bioimaging is discussed, as the specific bioimaging application and the experimental setup for infrared imaging determine the neodymium-doped nanoparticle to be preferentially used in each case.

  16. Lattice thermal expansion and solubility limits of neodymium-doped ceria

    NASA Astrophysics Data System (ADS)

    Zhang, Jinhua; Ke, Changming; Wu, Hongdan; Yu, Jishun; Wang, Jingran

    2016-11-01

    NdxCe1-xO2-0.5x (x=0-1.0) powders were prepared by reverse coprecipitation-calcination method and characterized by XRD. The crystal structure of product powders transformed from single fluorite structure to the complex of fluorite and C-type cubic structure, and finally to trigonal structure with the increase of x-value. An empirical equation simulating the lattice parameter of neodymium doped ceria was established based on the experimental data. The lattice parameters of the fluorite structure solid solutions increased with extensive adoption of Nd3+, and the heating temperature going up. The average thermal expansion coefficients of neodymium doped ceria with fluorite structure are higher than 13.5×10-6 °C-1 from room temperature to 1200 °C.

  17. Solar nebula heterogeneity in p-process samarium and neodymium isotopes.

    PubMed

    Andreasen, Rasmus; Sharma, Mukul

    2006-11-03

    Bulk carbonaceous chondrites display a deficit of approximately 100 parts per million (ppm) in 144Sm with respect to other meteorites and terrestrial standards, leading to a decrease in their 142Nd/144Nd ratios by approximately 11 ppm. The data require that samarium and neodymium isotopes produced by the p process associated with photodisintegration reactions in supernovae were heterogeneously distributed in the solar nebula. Other samarium and neodymium isotopes produced by rapid neutron capture (r process) in supernovae and by slow neutron capture (s process) in red giants were homogeneously distributed. The supernovae sources supplying the p- and r-process nuclides to the solar nebula were thus disconnected or only weakly connected.

  18. Broadening of paramagnetic resonance lines by charged point defects in neodymium-doped scheelites

    NASA Astrophysics Data System (ADS)

    Baibekov, E. I.; Zverev, D. G.; Kurkin, I. N.; Rodionov, A. A.; Malkin, B. Z.; Barbara, B.

    2014-05-01

    We study paramagnetic resonance linewidth in a series of CaWO4 and CaMoO4 crystals with different concentrations of neodymium ions (0.0031-0.81 at %). Experimental data are interpreted in the framework of the statistical theory of line broadening by charged point defects. In our calculations, three different contributions are singled out: arising from the local electric fields, electric field gradients and magnetic fields of the nearby point defects. The interaction parameters are determined from the spectroscopic data available for Nd:CaWO4 crystal. Direct calculations of the linewidth are performed for different crystal orientations with respect to external magnetic field. We conclude that major contribution to the broadening comes from the interactions with random electric fields produced by neodymium and charge compensator ions.

  19. Influence of admixtures on the crystallization and properties of neodymium pentaphosphate

    NASA Astrophysics Data System (ADS)

    Litvin, B. N.; Bebikh, L. G.

    1982-05-01

    Neodymium pentaphosphate monocrystals of good quality were grown from phosporic acid solutions containing alkaline metals, Sb and Pb admixtures. The changes in the crystal habit are connected with the properties of the interacting admixtures, and the (P 10O 28) ∞ ribbons which distinguish the structure of pentaphosphates. The presence of B, Al, Si, Ge, Cr and Mn does not influence the quality of the crystals. The NdP 5O 14 grown from the K-containing solution was tested, for CW generation with α = 1.05 μm and a second harmonic pumping of the neodymium laser (λ = 0.53 μm, frequency = 12.5 Hz) using a resonator consisting of spherical ( R = 5 cm) and plane mirrors ( R = 99.8%) with a threshold pumping of 56 μJ.

  20. Neodymium-doped nanoparticles for infrared fluorescence bioimaging: The role of the host

    NASA Astrophysics Data System (ADS)

    del Rosal, Blanca; Pérez-Delgado, Alberto; Misiak, Małgorzata; Bednarkiewicz, Artur; Vanetsev, Alexander S.; Orlovskii, Yurii; Jovanović, Dragana J.; Dramićanin, Miroslav D.; Rocha, Ueslen; Upendra Kumar, K.; Jacinto, Carlos; Navarro, Elizabeth; Martín Rodríguez, Emma; Pedroni, Marco; Speghini, Adolfo; Hirata, Gustavo A.; Martín, I. R.; Jaque, Daniel

    2015-10-01

    The spectroscopic properties of different infrared-emitting neodymium-doped nanoparticles (LaF3:Nd3+, SrF2:Nd3+, NaGdF4: Nd3+, NaYF4: Nd3+, KYF4: Nd3+, GdVO4: Nd3+, and Nd:YAG) have been systematically analyzed. A comparison of the spectral shapes of both emission and absorption spectra is presented, from which the relevant role played by the host matrix is evidenced. The lack of a "universal" optimum system for infrared bioimaging is discussed, as the specific bioimaging application and the experimental setup for infrared imaging determine the neodymium-doped nanoparticle to be preferentially used in each case.

  1. Neodymium lasers as a source of synchronized high-power optical pulses

    NASA Astrophysics Data System (ADS)

    Sizer, Theodore, II; Duling, Irl N., III

    1988-02-01

    The recent considerable progress in the development of solid-state lasers, primarily neodymium-based lasers for use as sources of short, synchronized, high-power optical pulses, is reviewed. The amplification of femtosecond optical pulses using synchronous amplification techniques with these lasers has proved particularly applicable to experimentation. The authors also presents a laser design which combines several advantageous qualities into a single laser cavity.

  2. Development of a novel neodymium compound for in vivo fluorescence imaging.

    PubMed

    Aita, Kazuki; Temma, Takashi; Kuge, Yuji; Saji, Hideo

    2007-01-01

    We developed a novel fluorescent probe that contains the neodymium(III) complex moiety and fluorescein moiety. This probe can emit long-lived near-infrared luminescence derived from a Nd ion through excitation of the fluorescein moiety with visible light (lambda(ex) = 488 nm, lambda(em) = 880 nm, lifetime = 2.3 micros). These results indicate the possibility of the probe as a candidate for in vivo fluorescence molecular imaging.

  3. Neodymium(III) Complexation by Amino-Carbohydrates via a Ligand-Controlled Hydrolysis Mechanism

    SciTech Connect

    Levitskaia, Tatiana G.; Chen, Yongsheng; Fulton, John L.; Sinkov, Sergey I.

    2011-07-28

    Chelation of neodymium-III Nd(III) by D-glucosamine (DGA) and chitosan was investigated in solution at near-physiological pH and ionic strength. This research demonstrates the first example of the lanthanide ion heteroleptic hydroxo-carbohydrate complex in solution. It was demonstrated that DGA and chitosan suppressed formation of polynuclear Nd(III) species at elevated pH.

  4. Neodymium isotopic composition and concentration in the western North Atlantic Ocean: Results from the GEOTRACES GA02 section

    NASA Astrophysics Data System (ADS)

    Lambelet, Myriam; van de Flierdt, Tina; Crocket, Kirsty; Rehkämper, Mark; Kreissig, Katharina; Coles, Barry; Rijkenberg, Micha J. A.; Gerringa, Loes J. A.; de Baar, Hein J. W.; Steinfeldt, Reiner

    2016-03-01

    The neodymium (Nd) isotopic composition of seawater is commonly used as a proxy to study past changes in the thermohaline circulation. The modern database for such reconstructions is however poor and the understanding of the underlying processes is incomplete. Here we present new observational data for Nd isotopes and concentrations from twelve seawater depth profiles, which follow the flow path of North Atlantic Deep Water (NADW) from its formation region in the North Atlantic to the northern equatorial Atlantic. Samples were collected during two cruises constituting the northern part of the Dutch GEOTRACES transect GA02 in 2010. The results show that the different water masses in the subpolar North Atlantic Ocean, which ultimately constitute NADW, have the following Nd isotope characteristics: Upper Labrador Sea Water (ULSW), εNd = -14.2 ± 0.3; Labrador Sea Water (LSW), εNd = -13.7 ± 0.9; Northeast Atlantic Deep Water (NEADW), εNd = -12.5 ± 0.6; Northwest Atlantic Bottom Water (NWABW), εNd = -11.8 ± 1.4. In the subtropics, where these source water masses have mixed to form NADW, which is exported to the global ocean, upper-NADW is characterised by εNd values of -13.2 ± 1.0 (2sd) and lower-NADW exhibits values of εNd = -12.4 ± 0.4 (2sd). While both signatures overlap within error, the signature for lower-NADW is significantly more radiogenic than the traditionally used value for NADW (εNd = -13.5) due to the dominance of source waters from the Nordic Seas (NWABW and NEADW). Comparison between the concentration profiles and the corresponding Nd isotope profiles with other water mass properties such as salinity, silicate concentrations, neutral densities and chlorofluorocarbon (CFC) concentration provides novel insights into the geochemical cycle of Nd and reveals that different processes are necessary to account for the observed Nd characteristics in the subpolar and subtropical gyres and throughout the vertical water column. While our data set

  5. Powerful neodymium laser radiation for the treatment of facial carcinoma: 5 year follow-up data.

    PubMed

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

    2010-01-01

    A retrospective non-comparative follow-up study was performed to evaluate the curative efficacy of powerful neodymium laser radiation (λ = 1,060 nm) for the treatment of 2,837 patients with 3,001 histologically confirmed facial skin carcinoma lesions of stages T1-2N0M0: 2,743 primary basal cell carcinomas (BCC), 172 recurrent limited basal cell carcinomas (RLBCC), and 86 primary squamous cells carcinomas (SCC). All patients were followed-up from 5 to 11 years (mean: 8.2 years; median: 7.0 years) after treatment. The overall recurrence rate (RR) after treatment with laser radiation of facial carcinomas was 2.5% of all irradiated tumours (mean: 13.4 months; median: 11.0 months). Patients with BCC treated by radiation with the pulsed Neodymium (Nd) laser developed RR in 2.2% of cases and patients treated with the Nd:YAG laser had RR of 3.1%. Recurrences following treatment for RLBCC, and those of SCC, after irradiation with the Nd laser appeared in 4.1% and 4.6% of patients, respectively. Neodymium laser radiation is a safe and effective means of treating facial carcinomas of stages T1-2N0M0 with good cosmetic results.

  6. Stability of the complexes of some lanthanides with coumarin derivatives. II. Neodymium(III)-acenocoumarol.

    PubMed

    Kostova, Irena; Manolov, Ilia; Radulova, Maritza

    2004-06-01

    A complex of neodymium(III) with 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (acenocoumarol) was synthesized by mixing water solutions of neodymium(III) nitrate and the ligand (metal to ligand molar ratio of 1:3). The complex was characterized and identified by elemental analysis, conductivity, IR, 1H NMR and mass spectral data. DTA and TGA were applied to study the composition of the compound. Elemental and mass spectral analysis of the complex indicated the formation of a compound of the composition NdR3 x 6H2O, where R = C19H14NO6-) The reaction of neodymium(III) with acenocoumarol was studied in detail by the spectrophotometric method. The stepwise formation of three complexes, vis., NdR2+, NdR2+ and NdR3 was established in the pH region studied (pH 3.0-7.5). The equilibrium constants for 1:1, 1:2 and 1:3 complexes were determined to be log K1 = 6.20 +/- 0.06; log K2 = 3.46 +/- 0.07 and log K2) = 2.58 +/- 0.05, respectively.

  7. Subtissue thermal sensing based on neodymium-doped LaF₃ nanoparticles.

    PubMed

    Rocha, Uéslen; Jacinto da Silva, Carlos; Ferreira Silva, Wagner; Guedes, Ilde; Benayas, Antonio; Martínez Maestro, Laura; Acosta Elias, Mónica; Bovero, Enrico; van Veggel, Frank C J M; García Solé, José Antonio; Jaque, Daniel

    2013-02-26

    In this work, we report the multifunctional character of neodymium-doped LaF₃ core/shell nanoparticles. Because of the spectral overlap of the neodymium emission bands with the transparency windows of human tissues, these nanoparticles emerge as relevant subtissue optical probes. For neodymium contents optimizing the luminescence brightness of Nd³⁺:LaF₃ nanoparticles, subtissue penetration depths of several millimeters have been demonstrated. At the same time, it has been found that the infrared emission bands of Nd³⁺:LaF₃ nanoparticles show a remarkable thermal sensitivity, so that they can be advantageously used as luminescent nanothermometers for subtissue thermal sensing. This possibility has been demonstrated in this work: Nd³⁺:LaF₃ nanoparticles have been used to provide optical control over subtissue temperature in a single-beam plasmonic-mediated heating experiment. In this experiment, gold nanorods are used as nanoheaters while thermal reading is performed by the Nd³⁺:LaF₃ nanoparticles. The possibility of a real single-beam-controlled subtissue hyperthermia process is, therefore, pointed out.

  8. Separation of samarium and neodymium: a prerequisite for getting signals from nuclear synthesis.

    PubMed

    Maji, Samir; Lahiri, Susanta; Wierczinski, Birgit; Korschinek, Gunther

    2006-12-01

    (146)Sm (T(1/2) = 10(8) y) is a long-lived radionuclide which has been produced in significant amounts during burning in a supernova (SN). Detection of this SN produced long-lived radionuclide on Earth may be helpful for getting information on nuclear synthesis at the time of our solar system's formation. Only accelerator mass spectrometry (AMS) can determine such minute traces of (146)Sm still expected in the Earth's crust. However, the villain of (146)Sm measurement through AMS is its naturally occurring stable isobar (146)Nd which is a million times more abundant than the trace amount of (146)Sm. Therefore an efficient method for the separation of samarium and neodymium is required to measure (146)Sm through AMS. A simple liquid-liquid extraction (LLX) based method for separation of samarium and neodymium has been developed using radiometric simulation. Di-(2-ethylhexyl)phosphoric acid (HDEHP) has been used as the organic reagent. A very high separation factor ( approximately 10(6)) can be achieved when a solution containing samarium and neodymium is reduced by hydroxylamine hydrochloride followed by extraction with 0.1% HDEHP diluted in cyclohexane from 0.025 M HCl solution.

  9. X-ray radiometric determination of lanthanides (praseodymium, neodymium, and samarium) in soils

    NASA Astrophysics Data System (ADS)

    Savichev, A. T.; Vodyanitskii, Yu. N.

    2011-04-01

    A procedure of the modified energy-dispersive X-ray fluorescence method (X-ray radiometric analysis using a 241Am radionuclide source) was developed for the identification of praseodymium, neodymium, and samarium. The procedure is based on the exclusion of the disturbing effect of barium and lanthanum on the lines of praseodymium and neodymium, as well as the effect of lanthanum and cerium on the lines of samarium. On the basis of the new method, data were obtained on the geochemistry of three lanthanides in soils of the northern taiga. Praseodymium and neodymium were detected by the X-ray radiometric method even in podzols depleted of heavy metals. The method can detect samarium at the levels of the soil clarke and higher. Positive samarium (or, wider, rare-earth) anomalies can be expected in the soils located not far from the deposits of apatite-nephelines, loparites, and phosphorites and in the soils developed on alkaline granites and carbonate weathering crusts.

  10. Safety and efficacy of Neodymium-Yag laser photocoagulation: an experimental study in dogs.

    PubMed Central

    Rutgeerts, P; Vantrappen, G; Geboes, K; Broeckaert, L

    1981-01-01

    Acute and chronic experiments were carried out in 26 beagle dogs to study the safety and efficacy of Neodymium-Yag laser photocoagulation in the treatment of bleeding gastric lesions. Continuous high power (50-60 W) Neodymium-Yag laser photocoagulation applied to the exposed stomach of the dog produced evaporation lesions that reached the muscle layer after six to 10 seconds and caused free perforation after 10 to 12 seconds. The tissue damage caused by these long lasting exposures was closely related to the working distance. Moreover, long pulses of high power photocoagulation were not always effective in stopping experimentally induced gastric bleedings. Short pulses (1/2-1 s) of very high power (60-70 W) caused less tissue evaporation, which reached the muscle layers only after 14 to 18 pulses and caused free perforation after 22 to 24 pulses. The tissue damage was not related to the working distance when short pulses were used. Repeated shots of high power Yag laser radiation always resulted in stopping the experimental bleedings without deep injury. It is concluded that high power Neodymium-Yag laser photocoagulation is safe and may be used with success in the treatment of bleeding gastric lesions if the radiation is performed in shots of short duration (1 s or less). Clinical studies in man are warranted and indicated. Images Fig. 3 Fig. 7 Fig. 8 PMID:7193164

  11. Neodymium(III) Complexes Capable of Multi-Electron Redox Chemistry.

    PubMed

    Coughlin, Ezra J; Zeller, Matthias; Bart, Suzanne C

    2017-09-25

    A family of neodymium complexes featuring a redox-active ligand in three different oxidation states has been synthesized, including the iminoquinone (L(0) ) derivative, ((dipp) iq)2 NdI3 (1-iq), the iminosemiquinone (L(1-) ) compound, ((dipp) isq)2 NdI(THF) (1-isq), and the amidophenolate (L(2-) ) [K(THF)2 ][((dipp) ap)2 Nd(THF)2 ] (1-ap) and [K(18-crown-6)][((dipp) ap)2 Nd(THF)2 ] (1-ap crown) species. Full spectroscopic and structural characterization of each derivative established the +3 neodymium oxidation state with redox chemistry occurring at the ligand rather than the neodymium center. Oxidation with elemental chalcogens showed the reversible nature of the ligand-mediated reduction process, forming the iminosemiquinone metallocycles, [K(18-crown-6)][((dipp) isq)2 Nd(S5 )] (2-isq crown) and [K(18-crown-6)(THF)][((dipp) isq)2 Nd(Se5 )] (3-isq crown), which are characterized to contain a 6-membered twist-boat ring. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Alkali Silicate Vehicle Forms Durable, Fireproof Paint

    NASA Technical Reports Server (NTRS)

    Schutt, John B.; Seindenberg, Benjamin

    1964-01-01

    The problem: To develop a paint for use on satellites or space vehicles that exhibits high resistance to cracking, peeling, or flaking when subjected to a wide range of temperatures. Organic coatings will partially meet the required specifications but have the inherent disadvantage of combustibility. Alkali-silicate binders, used in some industrial coatings and adhesives, show evidence of forming a fireproof paint, but the problem of high surface-tension, a characteristic of alkali silicates, has not been resolved. The solution: Use of a suitable non-ionic wetting agent combined with a paint incorporating alkali silicate as the binder.

  13. Cytotoxic activity of new neodymium (III) complexes of bis-coumarins.

    PubMed

    Kostova, Irena; Manolov, Ilia; Momekov, Georgi

    2004-09-01

    Complexes of neodymium (III) with bis-coumarins: 3,3'-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one); bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-2-yl-methane; bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-4-yl-methane; bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-(1H-pyrazol-3-yl)-methane were synthesized by reaction of neodymium (III) salt and the ligands, in amounts equal to metal:ligand molar ratio of 1:2. The complexes were prepared by adding an aqueous solution of neodymium (III) salt to an aqueous solution of the ligand subsequently raising the pH of the mixture gradually to ca. 5.0 by adding dilute solution of sodium hydroxide. The neodymium (III) complexes with bis-coumarins were characterized by different physicochemical methods-elemental analysis, IR-, (1)H- and (13)C-NMR-spectroscopies and mass-spectral data. The spectral data of neodymium (III) complexes were interpreted on the basis of comparison with the spectra of the free ligands. This analysis showed that in the Nd (III) complexes the ligands coordinated to the metal ion through both deprotonated hydroxyl groups. On the basis of the nu(C=O) red shift observed, participation of the carbonyl groups in the coordination to the metal ion was also suggested. Cytotoxic screening by MTT assay was carried out. The complexes were tested on HL-60, HL-60/Dox and SKW-3 cell lines. The overall results from the preliminary screening program revealed that all of the new Nd (III) complexes reach 50% inhibition of the malignant cells proliferation and thus could be considered as biologically active. On the basis of the IC(50) values obtained compounds Nd(L(1))(OH).H(2)O and Nd(L(3))(OH).2H(2)O were found to exert superior activity in comparison to the remaining complexes.

  14. Laser processing of siliceous materials

    NASA Astrophysics Data System (ADS)

    Panzner, Michael; Lenk, Andreas; Wiedemann, Guenter R.; Hauptmann, Jan; Weiss, Hans J.; Ruemenapp, Thomas; Morgenthal, Lothar; Beyer, Eckhard

    2000-08-01

    Laser processing of siliceous materials becomes increasingly important. Analogous to the laser processing of conventional materials there are applications in the fields of cleaning, surface processing, cutting, etc. The present paper concerns the state of the art and new applications: (1) Laser cleaning of natural stone surfaces. The good disability allows restoration work to be carried out conveniently, as for example the complete removal of crusts or the removal to such degree that moisture is not trapped beneath. (2) Non-slip finish of polished natural stone surfaces: The excellent focusing of laser beams on spots as small as 100 micrometer and below can be exploited to produce macroscopically invisible structures on the surfaces of different materials. This permits microscopically small craters and lentil shaped depressions to be generated on the stone surface. Therefore it is possible to provide a non-slip finish to polished natural stone surfaces without noticeably impairing the gloss. (3) Concrete cutting: In Europe, and particularly in Germany, there is a growing demand for redevelopment of concrete apartment buildings, involving the removal of non-bearing walls and the cutting of openings. The temporal relocation of residents due to the noise and moisture from the use of diamond tools could be avoided by applying a laser cutting technology. With a 3 kW-Nd-YAG-laser, 70 mm concrete can be cut with rates up to 25 mm/min.

  15. Organically modified silicate aerogels, ``Aeromosils``

    SciTech Connect

    Kramer, S.J.; Mackenzie, J.D.; Rubio-Alonso, F.

    1996-12-31

    Aerogels derived from sol-gel oxides such as silica have become quite scientifically popular because of their extremely low densities, high surface areas, and their interesting optical, dielectric, thermal and acoustic properties. However, their commercial applicability has thus far been rather limited, due in great part to their brittleness and hydrophilicity. In prior work by the research group, modifying silicate gel structures with flexible, organic containing polymers such as polydimethylsiloxane imparted significant compliance (even rubbery behavior) and hydrophobicity. These materials have been referred to as Ormosils. This study expounds on the current effort to extend these desirable properties to aerogels, and in-so-doing, creating novel ``Aeromosils``. Reactive incorporation of hydroxy-terminal polydimethylsiloxane (PDMS) into silica sol-gels was made using both acid and two-step acid/base catalyzed processes. Aerogels were derived by employing the supercritical CO{sub 2} technique. Analyses of microstructure were made using nitrogen adsorption (BET surface area and pore size distribution), and some mechanical strengths were derived from tensile strength testing. Interesting Aeromosil properties obtained include optical transparency, surface areas of up to 1,200 m{sup 2}/g, rubberiness, and better strength than corresponding silica aerogels with elongations at break exceeding 5% in some cases.

  16. Improved alkali-metal/silicate binders

    NASA Technical Reports Server (NTRS)

    Schutt, J.

    1978-01-01

    Family of inorganic binders utilizes potassium or sodium oxide/silicate dispersion and employs high mole ratio of silicon dioxide to alkali-metal binder. Binders are stable, inexpensive, extremely water resistant, and easy to apply.

  17. Highly silicic compositions on the Moon.

    PubMed

    Glotch, Timothy D; Lucey, Paul G; Bandfield, Joshua L; Greenhagen, Benjamin T; Thomas, Ian R; Elphic, Richard C; Bowles, Neil; Wyatt, Michael B; Allen, Carlton C; Donaldson Hanna, Kerri; Paige, David A

    2010-09-17

    Using data from the Diviner Lunar Radiometer Experiment, we show that four regions of the Moon previously described as "red spots" exhibit mid-infrared spectra best explained by quartz, silica-rich glass, or alkali feldspar. These lithologies are consistent with evolved rocks similar to lunar granites in the Apollo samples. The spectral character of these spots is distinct from surrounding mare and highlands material and from regions composed of pure plagioclase feldspar. The variety of landforms associated with the silicic spectral character suggests that both extrusive and intrusive silicic magmatism occurred on the Moon. Basaltic underplating is the preferred mechanism for silicic magma generation, leading to the formation of extrusive landforms. This mechanism or silicate liquid immiscibility could lead to the formation of intrusive bodies.

  18. Prometheus Silicates/Sulfur dioxide/NIMS

    NASA Image and Video Library

    2000-05-18

    The Prometheus region of Jupiter moon Io was imaged by NASA Galileo spacecraft in 1999. The maps made from spectrometer data show the interplay between hot silicates on the surface and sulfur dioxide frost.

  19. Influence of Silicate Melt Composition on Metal/Silicate Partitioning of W, Ge, Ga and Ni

    NASA Technical Reports Server (NTRS)

    Singletary, S. J.; Domanik, K.; Drake, M. J.

    2005-01-01

    The depletion of the siderophile elements in the Earth's upper mantle relative to the chondritic meteorites is a geochemical imprint of core segregation. Therefore, metal/silicate partition coefficients (Dm/s) for siderophile elements are essential to investigations of core formation when used in conjunction with the pattern of elemental abundances in the Earth's mantle. The partitioning of siderophile elements is controlled by temperature, pressure, oxygen fugacity, and by the compositions of the metal and silicate phases. Several recent studies have shown the importance of silicate melt composition on the partitioning of siderophile elements between silicate and metallic liquids. It has been demonstrated that many elements display increased solubility in less polymerized (mafic) melts. However, the importance of silicate melt composition was believed to be minor compared to the influence of oxygen fugacity until studies showed that melt composition is an important factor at high pressures and temperatures. It was found that melt composition is also important for partitioning of high valency siderophile elements. Atmospheric experiments were conducted, varying only silicate melt composition, to assess the importance of silicate melt composition for the partitioning of W, Co and Ga and found that the valence of the dissolving species plays an important role in determining the effect of composition on solubility. In this study, we extend the data set to higher pressures and investigate the role of silicate melt composition on the partitioning of the siderophile elements W, Ge, Ga and Ni between metallic and silicate liquid.

  20. Peralkaline silicic volcanic rocks in northwestern nevada.

    PubMed

    Noble, D C; Chipman, D W; Giles, D L

    1968-06-21

    Late Tertiary silicic ashflow tuffs and lavas peralkaline in chemical character (atomic Na + K greater than Al), mainly comendites, occur over wide areas in northwestern Nevada and appear to be widespread in southeastern Oregon. Such peralkaline rocks-which are not uncommon in the western United States-and other chemically unusual silicic rocks are found near the margins rather than toward the center of the Great Basin.

  1. Thermodynamics and Kinetics of Silicate Vaporization

    NASA Technical Reports Server (NTRS)

    Jacobson, Nathan S.; Costa, Gustavo C. C.

    2015-01-01

    Silicates are a common class of materials that are often exposed to high temperatures. The behavior of these materials needs to be understood for applications as high temperature coatings in material science as well as the constituents of lava for geological considerations. The vaporization behavior of these materials is an important aspect of their high temperature behavior and it also provides fundamental thermodynamic data. The application of Knudsen effusion mass spectrometry (KEMS) to silicates is discussed. There are several special considerations for silicates. The first is selection of an appropriate cell material, which is either nearly inert or has well-understood interactions with the silicate. The second consideration is proper measurement of the low vapor pressures. This can be circumvented by using a reducing agent to boost the vapor pressure without changing the solid composition or by working at very high temperatures. The third consideration deals with kinetic barriers to vaporization. The measurement of these barriers, as encompassed in a vaporization coefficient, is discussed. Current measured data of rare earth silicates for high temperature coating applications are discussed. In addition, data on magnesium-iron-silicates (olivine) are presented and discussed.

  2. Helical core optical fibre made of Nd3+/Yb3+-doped oxyfluoride silicate glass

    NASA Astrophysics Data System (ADS)

    Dorosz, D.; Kochanowicz, M.; Zmojda, J.; Dorosz, J.

    2010-05-01

    The properties of helical-core optical fibre made by authors from Nd3+/Yb3+-doped oxyfluoride silicate glass are presented. The construction and forming conditions of the helical-core optical fibre enabled to obtain the helix pitch from several mm and the off-set ranging from 10 μm to 200 μm. The paper also presents optimisation of Nd3+/Yb3+ ratio to enhance the emission bandwidth at 1 μm. In consequence of matching the values of the emission cross-section σem(Nd)and the absorption cross-section σabs(Yb) in the glass doped with 0.15Nd3+:0.45Yb3+ a broad (Δλ = 100nm) luminescence band in the vicinity of 1μm was obtained, which was the result of overlapping emission transitions: 2F5/2-->2F7/2 in ytterbium and 4F3/2-->4I11/2 in neodymium.

  3. Interpreting the 10 micron Astronomical Silicate Feature

    NASA Astrophysics Data System (ADS)

    Bowey, Janet E.

    1998-11-01

    10micron spectra of silicate dust in the diffuse medium towards Cyg OB2 no. 12 and towards field and embedded objects in the Taurus Molecular Cloud (TMC) were obtained with CGS3 at the United Kingdom Infrared Telescope (UKIRT). Cold molecular-cloud silicates are sampled in quiescent lines of sight towards the field stars Taurus-Elias 16 and Elias 13, whilst observations of the embedded young stellar objects HL Tau, Taurus-Elias 7 (Haro6-10) and Elias 18 also include emission from heated dust. To obtain the foreground silicate absorption profiles, featureless continua are estimated using smoothed astronomical and laboratory silicate emissivities. TMC field stars and Cyg OB2 no. 12 are modelled as photospheres reddened by foreground continuum and silicate extinction. Dust emission in the non-photospheric continua of HL Tau and Elias 7 (Haro6-10) is distinguished from foreground silicate absorption using a 10micron disk model, based on the IR-submm model of T Tauri stars by Adams, Lada & Shu (1988), with terms added to represent the foreground continuum and silicate extinction. The absorption profiles of HL Tau and Elias 7 are similar to that of the field star Elias 16. Fitted temperature indices of 0.43 (HL Tau) and 0.33 (Elias 7) agree with Boss' (1996) theoretical models of the 200-300K region, but are lower than those of IR-submm disks (0.5-0.61; Mannings & Emerson 1994); the modelled 10micron emission of HL Tau is optically thin, that of Elias 7 is optically thick. A preliminary arcsecond-resolution determination of the 10micron emissivity near θ1 Ori D in the Trapezium region of Orion and a range of emission temperatures (225-310K) are derived from observations by T. L. Hayward; this Ney-Allen emissivity is 0.6micron narrower than the Trapezium emissivity obtained by Forrest et al. (1975) with a large aperture. Published interstellar grain models, elemental abundances and laboratory studies of Solar System silicates (IDPs, GEMS and meteorites), the 10micron

  4. Phosphorus Equilibria Among Mafic Silicate Phases

    NASA Technical Reports Server (NTRS)

    Berlin, Jana; Xirouchakis, Dimitris

    2002-01-01

    Phosphorus incorporation in major rock-forming silicate minerals has the following implications: (1) Reactions between phosphorus-hosting major silicates and accessory phosphates, which are also major trace element carriers, may control the stability of the latter and thus may affect the amount of phosphorus and other trace elements released to the coexisting melt or fluid phase. (2) Less of a phosphate mineral is needed to account for the bulk phosphorus of planetaty mantles. (3) During partial melting of mantle mineral assemblages or equilibrium fractional crystallization of basaltic magmas, and in the absence or prior to saturation with a phosphate mineral, silicate melts may become enriched in phosphorus, especially in the geochemically important low melt fraction regime, Although the small differences in the ionic radii of IVp5+, IVSi4+, and IV Al3+ makes phosphoms incorporation into crystalline silicates perhaps unsurprising, isostructural silicate and phosphate crystalline solids do not readily form solutions, e.g., (Fe, Mg)2SiO4 vs. LiMgPO4, SiO)2 VS. AlPO4. Nonetheless, there are reports of, poorly characterized silico-phosphate phases in angrites , 2-4 wt% P2O5 in olivine and pyroxene grains in pallasites and reduced terestrial basalts which are little understood but potentially useful, and up to 17 wt% P2O5 in olivine from ancient slags. However, such enrichments are rare and only underscore the likelihood of phosphoms incorporation in silicate minerals. The mechanisms that allow phosphorus to enter major rock-forming silicate minerals (e.g., Oliv, Px, Gt) remain little understood and the relevant data base is limited. Nonetheless, old and new high-pressure (5-10 GPa) experimental data suggest that P2O5 wt% decreases from silica-poor to silica-rich compositions or from orthosilicate to chain silicate structures (garnet > olivine > orthopyroxene) which implies that phosphorus incorporation in silicates is perhaps more structure-than site-specific. The

  5. The geochemical balance of the rare earth elements and neodymium isotopes in the oceans

    SciTech Connect

    Bertram, C.J.; Elderfield, H. )

    1993-05-01

    Profiles of REE concentrations and neodymium isotope measurements in the western Indian Ocean are consistent with published data from the other major oceans. REE concentrations show a strong hydrographic control. The influence of intermediate water masses is particularly significant. Surface water concentrations vary with salinity. Particulate REEs are less than 5% of dissolved concentration, except for Ce, where up to [approximately]20% of total REEs are present as >0.4 [mu]m particles. In contrast to dissolved profiles, concentration profiles of particulate REEs, including Ce, all increase with depth. REE concentrations correlate with silica over all but the deepest waters, although, in detail, correlations are complex. The neodymium isotopic composition of Indian Ocean seawater (avg. [epsilon][sub Nd(0)] = [minus]8.3) is intermediate between that for the Atlantic and Pacific oceans. Comparison of REE data from the major oceans shows that the HREEs behave more like Si than do the LREEs. Sm/Nd ratios are near-constant for all oceans, whereas Er/Nd ratios vary between the Atlantic, Indian, and Pacific oceans. The fractionation of the REEs in surface seawaters can be explained by fractionation factors relative to silica from [approximately]0.12 for La to 0.05 for Er. Use of a seven-box model shows that the interoceanic variations in neodymium isotopic compositions and Nd concentrations cannot be reconciled unless particle-water exchange is invoked. The degree of exchange required is consistent with particle residence times of [approximately]1--10 yr. 54 refs., 18 figs., 4 tabs.

  6. Combination of Silicon and Neodymium Isotopes for a better understanding of past changes in bioproductivity and water mass mixing in the upwelling area off Peru

    NASA Astrophysics Data System (ADS)

    Grasse, P.; Ehlert, C.; Frank, M.; Stramma, L.

    2010-12-01

    The Peru coastal upwelling area is characterized by one of the most pronounced Oxygen Minimum Zones (OMZ). Oxygen concentrations are controlled by consumption through decomposition of organic matter versus ventilation via ocean circulation. Surface productivity is a function of both nutrient supply and upwelling intensity. The isotopic composition of Neodymium (Nd) is a powerful proxy for the reconstruction of past ocean circulation due to its intermediate oceanic residence time and the fact that it is independent of biological fractionation. This is in contrast to Silicon (Si) isotopes, which are fractionated during utilization in a way that the lighter Si isotopes are preferentially incorporated into the diatom frustules. The upwelling area off Peru is mainly influenced by water masses from the Central Pacific, which show more radiogenic values (ɛNd = -2), than water masses from the Northern Pacific (ɛNd = -5 to -3) or water masses from the south, which carry an unradiogenic Nd isotope signature originating from the Southern Ocean (ɛNd = -8 to -9). Upwelled Waters on the shelf are mainly supplied from the Equatorial Under Current (EUC) a strong southward flowing water mass originating in the western pacific. Therefore the δ30Si signal of diatoms is mainly influenced by the isotopic signal of the EUC. Past changes in the hydrography therefore would also influence the Si isotopic signal of this productivity proxy independent of silicic acid utilization. For a better understanding of the influence of water mass mixing on the isotopic signatures in the coastal upwelling area and the OMZ, we directly compare the Nd isotope signatures with dissolved stable Silicon isotope data. The information obtained from the unique combination of the biologically influenced Si isotopes and the Nd isotopes will lead to a better understanding of reconstruction of past ocean circulation and productivity.

  7. ACTIVE MEDIA. LASERS: Diode-array-pumped repetitively pulsed neodymium phosphate glass laser

    NASA Astrophysics Data System (ADS)

    Bogatov, A. P.; Drakin, A. E.; Miftakhutdinov, D. R.; Mikaelyan, G. T.; Starodub, A. N.

    2008-09-01

    Repetitively pulsed generation (200 μs, 40 Hz) was obtained in a neodymium phosphate glass laser pumped by a 870-nm diode array. The maximum slope lasing efficiency with respect to the optical pump energy equal to 13% is restricted by the factor (≈0.23) of active-medium filling by the mode field. By adjusting the laser cavity, the single-transverse mode regime, in particular, the generation of the TEM00 mode is obtained in the entire range of pump energies.

  8. [Some effects of the neodymium ion on the cell wall structure of Staphyloccocus aruea].

    PubMed

    Huo, Guang Hua; Zhang, Dong Yan; Zhang, Tong

    2007-12-01

    The aim of this research is to study the effect of neodymium ion on the cell wall structure of Staphyloccocus aruea using transmission electron microscope, amino acid analyzer, infrared absorption spectrometry (IR). Experimental results show that Nd3+ can change the shape and the structure of the cell wall of Staphyloccocus aruea NdCl3 with lower concentration than the bacteriostatic concentration can help to synthesize the cell wall structure of Staphyloccocus aruea. Nd3+ with higher concentration than the bacteriostatic concentration can break the peptide bond and the hydrogen bond so as to break the net structure in the peptideoglycan cell.

  9. Neodymium and lead isotope evidence for enriched early Archean crust in North America

    NASA Technical Reports Server (NTRS)

    Bowring, Samuel A.; Housh, Todd B.; Isachsen, Clark E.; Podosek, Frank A.; King, Janet E.

    1989-01-01

    Neodymium and lead isotope measurements and uranium-lead zircon geochronology from Archaean gneisses of the Slave Province in the Northwest Territories of Canada are reported. The gneisses contain zircons with cores older than 3.842 Gyr and an epsilon(Nd) (3.7 Gyr) of - 4.8. This is the oldest reported chondritic model age for a terrestrial sample and provides evidence for strongly enriched pre-3.8-Gyr crust, a reservoir complementary to the depleted mantle already in existence by 3.8 Gyr before the present.

  10. Laser amplifier based on a neodymium glass rod 150 mm in diameter

    SciTech Connect

    Shaykin, A A; Fokin, A P; Soloviev, A A; Kuzmin, A A; Shaikin, I A; Burdonov, K F; Khazanov, E A; Charukhchev, A V

    2014-05-30

    A unique large-aperture neodymium glass rod amplifier is experimentally studied. The small-signal gain distribution is measured at different pump energies. The aperture-averaged gain is found to be 2.3. The stored energy (500 J), the maximum possible pump pulse repetition rate, and the depolarisation in a single pulse and in a series of pulses with a repetition rate of one pulse per five minutes are calculated based on the investigations performed. It is shown that the use of this amplifier at the exit of the existing laser can increase the output pulse energy from 300 to 600 J. (lasers)

  11. Effect of reactor radiation on the operation of a neodymium inorganic liquid laser

    SciTech Connect

    Dobrovol'skii, A F; Kabakov, D V; Seregin, A A; Seregina, E A; Tikhonov, G V

    2009-02-28

    The radiation parameters of a neodymium liquid laser based on phosphorus oxychloride are measured upon irradiation of the laser medium by neutrons and gamma-rays from a BARS-6 two-zone reactor. This irradiation increases the laser energy by 20%-30% compared to the laser energy in the absence of irradiation. The lasing threshold is observed to decrease with increasing the irradiation dose. In the case of simultaneous optical and nuclear pumping of the laser medium, the free-running regime of laser operation converts to the regime of high-power pulses. (lasers)

  12. Bi-phasic titanium dioxide nanoparticles doped with nitrogen and neodymium for enhanced photocatalysis

    NASA Astrophysics Data System (ADS)

    Gomez, Virginia; Bear, Joseph C.; McNaughter, Paul D.; McGettrick, James D.; Watson, Trystan; Charbonneau, Cecile; O'Brien, Paul; Barron, Andrew R.; Dunnill, Charles W.

    2015-10-01

    Bi-phasic or multi-phasic composite nanoparticles for use in photocatalysis have been produced by a new synthetic approach. Sol-gel methods are used to deposit multiple layers of active material onto soluble substrates. In this work, a layer of rutile (TiO2) was deposited onto sodium chloride pellets followed by an annealing step and a layer of anatase. After dissolving the substrate, bi-phasic nanoparticles containing half anatase and half rutile TiO2; with ``Janus-like'' characteristics are obtained. Nitrogen and neodymium doping of the materials were observed to enhance the photocatalytic properties both under UV and white light irradiation. The unique advantage of this synthetic method is the ability to systematically dope separate sides of the nanoparticles. Nitrogen doping was found to be most effective on the anatase side of the nanoparticle while neodymium was found to be most effective on the rutile side. Rhodamine B dye was effectively photodegraded by co-doped particles under white light.Bi-phasic or multi-phasic composite nanoparticles for use in photocatalysis have been produced by a new synthetic approach. Sol-gel methods are used to deposit multiple layers of active material onto soluble substrates. In this work, a layer of rutile (TiO2) was deposited onto sodium chloride pellets followed by an annealing step and a layer of anatase. After dissolving the substrate, bi-phasic nanoparticles containing half anatase and half rutile TiO2; with ``Janus-like'' characteristics are obtained. Nitrogen and neodymium doping of the materials were observed to enhance the photocatalytic properties both under UV and white light irradiation. The unique advantage of this synthetic method is the ability to systematically dope separate sides of the nanoparticles. Nitrogen doping was found to be most effective on the anatase side of the nanoparticle while neodymium was found to be most effective on the rutile side. Rhodamine B dye was effectively photodegraded by co

  13. Neodymium-doped phosphate fiber lasers with an all-solid microstructured inner cladding.

    PubMed

    Zhang, Guang; Zhou, Qinling; Yu, Chunlei; Hu, Lili; Chen, Danping

    2012-06-15

    We report on high-power fiber lasers based on index-guiding, all-solid neodymium-doped (Nd-doped) phosphate photonic crystal fiber (PCF) with a hexagonal-shaped inner cladding. The optimum fiber laser with a 36 cm length active fiber, generated up to 7.92 W output power at 1053 nm, which benefited from a high absorption coefficient for pump power due to its noncircular inner cladding. The guiding properties of the all-solid PCF were also investigated. A stable mode with a donut-shaped profile and a power-dependent laser beam quality have been observed experimentally and analyzed.

  14. Neodymium neutron transmission and capture measurements and development of a new transmission detector

    NASA Astrophysics Data System (ADS)

    Barry, Devin P.

    Neodymium is a 235U fission product and is important in reactor neutronic calculations. The aim of this thesis is to improve upon the existing neutron cross section data of neodymium. Neutron capture and transmission measurements were performed by the time-of-flight technique at the Rensselaer Polytechnic Institute LINAC using metallic neodymium samples. The capture measurements were made at the 25-m flight station with a 16-segment Nal multiplicity detector, and the transmission measurements were performed at 15-m and 25-m flight stations, respectively, with 6Li glass scintillation detectors. After the data were collected and reduced, resonance parameters were determined by simultaneously fitting the transmission and capture data with the multilevel R-matrix Bayesian code SAMMY. The resonance parameters for all naturally occurring neodymium isotopes were deduced within the energy range of 1.0 eV to 500 eV. The resulting resonance parameters were used to calculate the capture resonance integral with this energy region and were compared to calculations obtained when using the resonance parameters from ENDF-B/VI. The RPI parameters gave a resonance integral value of 32 +/- 1 barns that is approximately 7% lower than that obtained with the ENDF-B/VI parameters. The current measurements significantly reduce the statistical uncertainties on the resonance parameters when compared with previously published parameters. This thesis also explains the resolution function in detail and discusses its importance when fitting experimental data to extract resonance parameters. More accurate resolution function parameters were determined for epithermal transmission and capture measurements by fitting well known resonances in Uranium-238. Improved transmission bare-bounce target in-beam photomultiplier tube (PMT) resolution function parameters were found and compared to those used previously at the RPI LINAC and a marked improvement in the quality of the fits is shown. In addition

  15. Study of structural and spectral properties of neodymium-doped lead-yttrium oxyfluoride nano-glass-ceramics

    NASA Astrophysics Data System (ADS)

    Bibik, A. Yu.; Nuryev, R. K.; Aseev, V. A.; Kolobkova, E. V.; Nikonorov, N. V.

    2015-06-01

    Processes of nanocrystalline phase formation in transparent yttrium oxyfluoride nano-glass-ceramics doped with neodymium ions are studied. An optimal heat treatment regime for a given glass composition is determined using differential thermal analysis (DTA). Glasses are heat-treated for 30, 60, and 120 min; the sizes of crystals are calculated, and the unit cell parameters are determined. The physicochemical and spectral properties of yttrium oxyfluoride glasses doped with neodymium ions, as well as of nano-glass-ceramics based on these glasses, are studied.

  16. Sustained Residence Times for Miocene Silicic Magmas of the Yellowstone Hotspot

    NASA Astrophysics Data System (ADS)

    Cathey, H. E.; Nash, B. P.

    2001-12-01

    The length of time over which large volume silicic magmas may persist in the crust is poorly constrained, and recent estimates have ranged from a few tens of thousands of years to over 1.0 myr. Compositional relationships among the ten eruptive units of the 12.7 - 10.5 Ma Cougar Point Tuff suggest that a common, long-lived reservoir for these magmas persisted throughout the 2.2 myr explosive phase of the Bruneau-Jarbidge eruptive center along the track of the Yellowstone hotspot. Low crystal content and high temperatures (usually greater than 900 degrees C) indicate that the magmas were close to their liquidi. Evidence for the persistence of several discrete magma volumes in the reservoir is contained in multiple compositional modes of glass in basal fallout tuffs and in the recurrence of identical sets of mineral compositional modes in successive eruptions. Multiple modes of glass composition are a common feature in many explosive eruptions of the Yellowstone hotspot. In the Cougar Point Tuff, recurrence intervals of identical modes of glass and pyroxene range from 0.3 to 1.1 Ma, and suggest residence times of similar duration. Pyroxene thermometry indicates that compositionally distinct liquids erupted in the same event differed in temperature by 25-70 degrees C. Eruption ages, pyroxene and glass compositions, magma temperatures, and isotopic ratios for the Cougar Point Tuff are consistent with a long-lived, dynamically evolving magma reservoir that was chemically and thermally zoned in a step-wise fashion, and composed of multiple discrete compositional layers. A continental hotspot, where heat is supplied continually to the lower crust by advection of basalt from the mantle, is the optimum tectonic setting for sustaining silicic melts near their liquidi for extended durations. Neodymium isotopic ratios in the Cougar Point Tuff increase systematically with successive eruptions (eNd -8.5 to -6.6), and record a substantial and increasing mantle contribution to the

  17. Molybdenum Valence in Basaltic Silicate Melts

    NASA Technical Reports Server (NTRS)

    Danielson, L. R.; Righter, K.; Newville, M.; Sutton, S.; Pando, K.

    2010-01-01

    The moderately siderophile element molybdenum has been used as an indicator in planetary differentiation processes, and is particularly relevant to core formation [for example, 1-6]. However, models that apply experimental data to an equilibrium differentiation scenario infer the oxidation state of molybdenum from solubility data or from multivariable coefficients from metal-silicate partitioning data [1,3,7]. Partitioning behavior of molybdenum, a multivalent element with a transition near the J02 of interest for core formation (IW-2) will be sensitive to changes in JO2 of the system and silicate melt structure. In a silicate melt, Mo can occur in either 4+ or 6+ valence state, and Mo6+ can be either octahedrally or tetrahedrally coordinated. Here we present first XANES measurements of Mo valence in basaltic run products at a range of P, T, and JO2 and further quantify the valence transition of Mo.

  18. Hydrothermal Synthesis of Dicalcium Silicate Based Cement

    NASA Astrophysics Data System (ADS)

    Dutta, N.; Chatterjee, A.

    2017-06-01

    It is imperative to develop low energy alternative binders considering the large amounts of energy consumed as well as carbon dioxide emissions involved in the manufacturing of ordinary Portland cement. This study is on the synthesis of a dicalcium silicate based binder using a low temperature hydrothermal route.The process consists of synthesizing an intermediate product consisting of a calcium silicate hydrate phase with a Ca:Si ratio of 2:1 and further thermal treatment to produce the β-Ca2SiO4 (C2S) phase.Effect of various synthesis parameters like water to solid ratio, dwell time and temperature on the formation of the desired calcium silicate hydrate phase is reported along with effect of heating conditions for formation of the β-C2S phase. Around 77.45% of β-C2S phase was synthesized by thermal treatment of the intermediate phase at 820°C.

  19. Core formation in silicate bodies

    NASA Astrophysics Data System (ADS)

    Nimmo, F.; O'Brien, D. P.; Kleine, T.

    2008-12-01

    Differentiation of a body into a metallic core and silicate mantle occurs most efficiently if temperatures are high enough to allow at least the metal to melt [1], and is enhanced if matrix deformation occurs [2]. Elevated temperatures may occur due to either decay of short-lived radio-isotopes, or gravitational energy release during accretion [3]. For bodies smaller than the Moon, core formation happens primarily due to radioactive decay. The Hf-W isotopic system may be used to date core formation; cores in some iron meteorites and the eucrite parent body (probably Vesta) formed within 1 My and 1-4~My of solar system formation, respectively [4]. These formation times are early enough to ensure widespread melting and differentiation by 26Al decay. Incorporation of Fe60 into the core, together with rapid early mantle solidification and cooling, may have driven early dynamo activity on some bodies [5]. Iron meteorites are typically depleted in sulphur relative to chondrites, for unknown reasons [6]. This depletion contrasts with the apparently higher sulphur contents of cores in larger planetary bodies, such as Mars [7], and also has a significant effect on the timing of core solidification. For bodies of Moon-size and larger, gravitational energy released during accretion is probably the primary cause of core formation [3]. The final stages of accretion involve large, stochastic collisions [8] between objects which are already differentiated. During each collision, the metallic cores of the colliding objects merge on timescales of a few hours [9]. Each collision will reset the Hf-W isotopic signature of both mantle and core, depending on the degree to which the impactor core re-equilibrates with the mantle of the target [10]. The re-equilibration efficiency depends mainly on the degree to which the impactor emulsifies [11], which is very uncertain. Results from N-body simulations [8,12] suggest that significant degrees of re- equilibration are required [4,10]. Re

  20. Reaction of silicate minerals to form tetramethoxysilane.

    PubMed

    Lewis, Larry N; Schattenmann, Florian J; Jordan, Tracey M; Carnahan, James C; Flanagan, William P; Wroczynski, Ronald J; Lemmon, John P; Anostario, Joseph M; Othon, Michelle A

    2002-05-06

    Several silicon dioxide sources were used as reagents in the base-mediated reaction with dimethyl carbonate (DMC) to make tetramethoxysilane (Q'). Several commercially available diatomaceous earth materials were investigated. High throughput screening was employed to explore over 200 silicate rocks and minerals as alternative silicon dioxide sources for formation of Q' from DMC and base. Amorphous silicon dioxide materials are effective reagents for the Q' forming reaction. Effective silicon dioxide sources in addition to the diatomaceous earth materials include opal and various synthetic silicates (Li, Co, and Ca).

  1. Mafic silicates in the Orgueil carbonaceous meteorite

    NASA Technical Reports Server (NTRS)

    Kerridge, J. F.; Macdougall, J. D.

    1976-01-01

    Iron-bearing olivines and pyroxenes occurring in Orgueil may represent a separate population distinct from the magnesian varieties previously reported. Compositions of these iron-bearing silicates are inconsistent with an origin by direct equilibrium condensation in the nebula. Such an origin is more plausible for the magnesian silicates, but lacks conclusive evidence. An extra-solar system origin for either mafic population is possible, though similarly lacking in evidence. About 15% of the olivines, randomly distributed with respect to iron content, retain particle track evidence of a precompaction irradiation.

  2. Statistics of silicate units in binary glasses.

    PubMed

    Gaddam, Anuraag; Montagne, Lionel; Ferreira, José M F

    2016-09-28

    In this paper, we derive a new model to determine the distribution of silicate units in binary glasses (or liquids). The model is based on statistical mechanics and assumes grand canonical ensemble of silicate units which exchange energy and network modifiers from the reservoir. This model complements experimental techniques, which measure short range order in glasses such as nuclear magnetic resonance (NMR) spectroscopy. The model has potential in calculating the amounts of liquid-liquid phase segregation and crystal nucleation, and it can be easily extended to more complicated compositions. The structural relaxation of the glass as probed by NMR spectroscopy is also reported, where the model could find its usefulness.

  3. Hydrothermal synthesis of ytterbium silicate nanoparticles.

    PubMed

    Chen, Hongfei; Gao, Yanfeng; Liu, Yun; Luo, Hongjie

    2010-02-15

    A simple, low-cost hydrothermal method was developed to synthesize 20-nm-diameter single-crystalline ytterbium silicate (Yb(2)Si(2)O(7) and Yb(2)SiO(5)) nanoparticles at 200 degrees C. This is nearly 1000 degrees C lower than that for the typical sol-gel route to ytterbium silicate powders. Obtained powders showed very low thermal conductivity, a suitable thermal expansion coefficient, and excellent thermal/structural stability, suggesting a potential application to environmental and thermal barrier coatings. Special focus was placed on assessing the hydrothermal reaction mechanism for particle formation.

  4. Antineoplastic activity of new lanthanide (cerium, lanthanum and neodymium) complex compounds.

    PubMed

    Kostova, Irena; Kostova, Raina; Momekov, Georgi; Trendafilova, Natasha; Karaivanova, Margarita

    2005-01-01

    Cerium (III), lanthanum (III) and neodymium (III) complexes with 3,3'-benzylidenebis[4-hydroxycoumarin] were synthesized in view of their application as cytotoxic agents. The complexes were characterized by different physicochemical methods: elemental analysis, mass spectrometry, 1H NMR, 13C NMR and IR spectroscopy. The spectra of the complexes were interpreted on the basis of comparison with the spectrum of the free ligand. The vibrational analysis showed that in the complexes the ligand coordinated to the metal ion through both deprotonated hydroxyl groups; however, participation of the carbonyl groups in the coordination to the metal ion was also suggested. The evaluation of the cytotoxic activity of the novel lanthanide complexes on HL-60 myeloid cells revealed that they are potent cytotoxic agents. The cerium complex was found to exhibit superior activity in comparison to the lanthanum and neodymium coordination compounds, the latter being the least active. Our data give us reason to conclude that the newly synthesized lanthanide complexes should be submitted to further more detailed pharmacological and toxicological evaluation.

  5. Investigation of Carboxylic Acid-Neodymium Conversion Films on Magnesium Alloy

    NASA Astrophysics Data System (ADS)

    Cui, Xiufang; Liu, Zhe; Lin, Lili; Jin, Guo; Wang, Haidou; Xu, Binshi

    2015-01-01

    The new carboxylic acid-neodymium anhydrous conversion films were successfully prepared and applied on the AZ91D magnesium alloy surface by taking absolute ethyl alcohol as solvent and four kinds of soluble carboxylic acid as activators. The corrosion resistance of the coating was measured by potentiodynamic polarization test in 3.5 wt.% NaCl solution in pH 7.0. The morphology, structure, and constituents of the coating were observed by scanning electron microscope, energy dispersivespectrum, x-ray photoelectron spectrum, and Fourier infrared spectrometer. Results show that corrosion resistance properties of samples coated with four different anhydrous conversion films were improved obviously. The corrosion potential increased, corrosion current density decreased, and polarization resistance increased. Among these four kinds of conversion films the one added with phytic exhibits the best corrosion resistant property. The mechanism of anhydrous-neodymium conversion film formation is also analyzed in this paper. It reveals that the gadolinium conversion coating is mainly composed of stable Nd2O3, MgO, Mg(OH)2, and carboxylate of Nd. And that the sample surface is rich in organic functional groups.

  6. Preparation of carbon nanotube-neodymium oxide composite and research on its catalytic performance

    SciTech Connect

    Zhao Lei; Wang Zhihua; Han Dongmei; Tao Dongliang; Guo Guangsheng

    2009-05-06

    Carbon Nanotube-Neodymium Oxide (CNT-Nd{sub 2}O{sub 3}) composite was prepared by using acid treated carbon nanotubes (CNTs) and neodymium nitrate in the presence of sodium dodecyl sulfate and ammonia liquid. Techniques of transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and differential thermal analysis (DTA) are used to characterize the morphology, structure, composition and catalytic property of the CNT-Nd{sub 2}O{sub 3} composite. The experimental results show that the Nd{sub 2}O{sub 3} nanoparticles, which have an average diameter of about 30-40 nm, are loaded on the surface of carbon nanotube. Compared with pure Nd{sub 2}O{sub 3} nanorods, the CNT-Nd{sub 2}O{sub 3} composite can catalyze the thermal decomposition of ammonium perchlorate more effectively. The sampling methods of the experimental samples made a difference on the catalytic experiment results, and the best catalytic result was obtained when de-ionized water served as the solvent of ammonium perchlorate.

  7. Simulation of the Magnetic Characteristics and Properties of the Neodymium Compensator of the Stiffness

    NASA Astrophysics Data System (ADS)

    Gurova, E. G.; Gurov, M. G.; Panchenko, Y. V.

    2016-08-01

    This research is devoted to consideration of the possibility to use the software ELCUT for development of the magnetic compensator of the stiffness based on neodymium magnets. The software represents precision enough apparatus to solve the issues of the magnetostatic. The solution of these issues is the most important phase at the stage of the designing and calculation of the magnetic compensator of the stiffness, so as at the beginning we need to find the traction force of the interaction between magnet and magnetic materials to provide necessary falling traction characteristic of the compensator. In this paper the simulated models of the neodymium magnets are shown; the view of the field are calculated, the plots of the distribution and directions of the magnetic field strength and induction vectors are presented. Results, which were obtained during of the simulation, further will be used for designing and creation of the magnetic compensator of the stiffness based on supermagnets. Research & Development is under the scholarship of the President of Russian Federation, order №184 from 10th of March 2015.

  8. Azo calix[4]arene based neodymium(III)-selective PVC membrane sensor.

    PubMed

    Menon, Shobhana K; Modi, Nishith R; Patel, Bhargav; Patel, Manishkumar B

    2011-02-15

    We found that the PVC membrane, containing azo calix[4]arene is a suitable ionophore, exhibited a Nernstian response for neodymium (Nd(3+)) ions (with slope of 19.8±0.2 mV decade(-1) for the triply charged ion) over a wide linear range of 4.0×10(-8) to 1.0×10(-1) mol L(-1) with a detection limit 1.0×10(-8) mol L(-1), a relatively fast response time, in the whole concentration range (<10 s), and a considerable life time at least for four months in the pH range of 4.0-8.0. Furthermore, the electrode revealed high selectivity with respect to all the common alkali, alkaline earth, transition and heavy metal ions, including the members of the lanthanide family other than Nd(3+). Concerning its applications, it was effectively employed for the determination of neodymium ions in industrial waste water as well as in lake water.

  9. Neodymium doped hydroxyapatite theranostic nanoplatforms for colon specific drug delivery applications.

    PubMed

    Victor, Sunita Prem; Paul, Willi; Vineeth, V M; Komeri, Remya; Jayabalan, Muthu; Sharma, Chandra P

    2016-09-01

    Theranostic nanoplatforms integrate therapeutic payloads with diagnostic agents, and help monitor therapeutic response. In this regard, stimuli responsive nanoplatforms further favour combinatorial therapeutic approach that can considerably improve efficacy and specificity of treatment. Herein, we present the engineering of a smart theranostic nanoplatform based on neodymium doped hydroxyapatite (HAN). The presence of neodymium endows the HAN nanoplatforms with near-infrared fluorescence capability. These HAN nanoparticles were then subsequently modified with alginic acid (HANA) to confer pH responsiveness to the synthesized nanoplatforms delivering them to the colon after oral administration. These nanoplatforms possessing optimum size, needle shaped morphology and negative zeta potential, are conducive to cellular internalization. On excitation at 410nm they exhibit near infrared emission at 670nm unraveling their theranostic capabilities. Cytotoxic effects systematically assessed using MTT and live dead assays reveal excellent viability. Raman microscopic imaging technique used to visualize uptake in HeLa cells demonstrate increased uptake from 4 to 16h, with growing cluster size and localization in the cytoplasm. Moreover the concomitant presence of alginic acid manifested advantages of augmented loading and pH dependent release profiles of the model drug, 4 acetyl salicylic acid (4ASA). We could thus establish a theranostic system for early tumour detection, targeted tumour therapy and monitoring of colon cancer that can be administered via the oral route.

  10. Spectroscopic properties of neodymium(III)-containing polyoxometalates in aqueous solution.

    PubMed

    But, Slawomir; Lis, Stefan; Deun, Rik Van; Parac-Vogt, Tatjana N; Görller-Walrand, Christiane; Binnemans, Koen

    2005-11-01

    The spectroscopic properties of the neodymium(III)-containing polyoxometalates (POMs) [Nd(PW(11)O(39))(2)](11-), [Nd(PMo(2)W(9)O(39))(2)](11-), [Nd(PMo(4)W(7)O(39))(2)](11-), [Nd(PMo(6)W(5)O(39))(2)](11-), [Nd(SiMo(2)W(9)O(39))(2)](13-), [Nd(P(2)W(17)O(61))(2)](17-), [NdW(10)O(36)](9-), [NdP(5)W(30)O(110)](12-) and [NdAs(4)W(40)O(140)](25-) are described. Absorption spectra of aqueous solutions of the complexes have been recorded and the transition intensities are parameterised in terms of the Judd-Ofelt intensity parameters Omega(lambda) (lambda=2, 4, 6). Marked differences were found between the luminescence lifetimes of the complexes of the type Nd(POM) and those of the type Nd(POM)(2), due to a better shielding of the neodymium(III) ions from the bulk water molecules in the latter type of complexes.

  11. Condensation reaction in the bandpass reaction cell improves sensitivity for uranium, thorium, neodymium and praseodymium measurements.

    PubMed

    Vais, Vladimir; Li, Chunsheng; Cornett, Jack

    2003-09-01

    Condensation reactions in the bandpass reaction cell or dynamic reaction cell (DRC) were used for the determination of actinides and lanthanides such as uranium, thorium, neodymium and praseodymium. These elements react with oxygen reagent gas in the dynamic reaction cell of the ELAN DRC II instrument to give mono- and/or dioxo cationic species (UO(2)+, ThO+, NdO+ and PrO+, respectively). Increasing the oxygen flow rate in the dynamic reaction cell leads to the rapid decrease of the singly charged metal ions accompanied by the fast increase in the intensity of the oxide ion. This phenomenon is used to improve considerably the sensitivity of ICP-MS instruments equipped with a dynamic reaction cell for actinides and lanthanides. Estimated detection limits (EDL) obtained in this work for uranium, thorium, neodymium-144 and praseodymium are 0.022, 1.0, 0.045, and 0.10 ng L(-1), respectively. The detection limit for uranium measured in the standard (vented) mode of an ELAN DRC II was found to be 0.22 ng L(-1), which is an order of magnitude higher compared to the pressurized mode.

  12. Selective Leaching Process for Neodymium Recovery from Scrap Nd-Fe-B Magnet

    NASA Astrophysics Data System (ADS)

    Lee, Ching-Hwa; Chen, Yu-Jung; Liao, Ching-Hua; Popuri, Srinivasa R.; Tsai, Shang-Lin; Hung, Chi-En

    2013-12-01

    Neodymium-iron-boron (Nd-Fe-B) magnets were most widely applied to permanent magnetic products in the world due to their high magnetic force. The increasing growth of scrap Nd-Fe-B magnets resulted in disposal problems and the reduction of neodymium (Nd) valuable resources. In this study, we developed a simple hydrometallurgical precipitation process with pH adjustment to separate and recover Nd 100 pct recovery from scrap Nd-Fe-B magnets. Several physical and chemical methods such as demagnetization, grinding, screening, and leaching processes were also adopted to investigate the recovery of Nd and other metals from scrap Nd-Fe-B magnets. The leaching process was carried out with four leaching reagents such as NaOH, HCl, HNO3, and H2SO4. Batch studies were also conducted to optimize the leaching operating conditions with respect to leaching time, concentration of leaching reagent, temperature, and solid/liquid ratio for both HCl and H2SO4 leaching reagents. Nd was successfully separated and recovered with 75.41 wt pct from optimized H2SO4 leaching solution through precipitation. Further, the purity and weight percentage of the obtained Nd product was analyzed using scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS) analysis. An X-ray diffraction (XRD) study confirmed the obtained product of Nd was in the form of NdOOH and Nd(OH)3.

  13. Neodymium:YAG laser coagulation prostatectomy: 3 years of experience with 227 patients.

    PubMed

    Kabalin, J N; Bite, G; Doll, S

    1996-01-01

    For 3 years we prospectively followed a cumulative cohort of men who underwent neodymium:YAG laser coagulation prostatectomy to relieve bladder outlet obstruction to determine the safety, efficacy and durability of this procedure. A total of 227 men with symptomatic bladder outlet obstruction was treated with the Urolase side-firing laser fiber between October 15, 1991 and October 15, 1994. Voiding outcomes, including peak urinary flow rates, residual urine volumes and American Urological Association symptom scores, were measured with time, and immediate and long-term complications were assessed. Median patient followup was 26 months (maximum 42). Significant improvement occurred in all measured voiding parameters, including 133% in peak flow rates and 61% in symptom scores 1 year postoperatively. Overall 87% of patients noticed improved quality of life as a result of surgery. Minimum postoperative followup was 6 months in all cases. Complications included prostatitis in 2.6% of patients, urethral stricture in 1.8%, bladder neck contracture in 4.4% and reoperation for residual prostate tissue in 5.3%. Neodymium:YAG laser coagulation of the prostate represents an efficacious surgical intervention for symptomatic bladder outlet obstruction with minimal associated morbidity. Voiding outcomes are durable through 3 years.

  14. Microfabrics in Siliceous Hotsprings: Yellowstone National Park, Wyoming

    NASA Technical Reports Server (NTRS)

    Guidry, S. A.; Chafetz, H. S.; Westall, F.

    2001-01-01

    Microfabrics shed light on the mechanisms governing siliceous sinter precipitation, the profound effects of microorganisms, as well as a conventional facies model for siliceous hotsprings. Additional information is contained in the original extended abstract.

  15. Microfabrics in Siliceous Hotsprings: Yellowstone National Park, Wyoming

    NASA Technical Reports Server (NTRS)

    Guidry, S. A.; Chafetz, H. S.; Westall, F.

    2001-01-01

    Microfabrics shed light on the mechanisms governing siliceous sinter precipitation, the profound effects of microorganisms, as well as a conventional facies model for siliceous hotsprings. Additional information is contained in the original extended abstract.

  16. 21 CFR 573.260 - Calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Calcium silicate. 573.260 Section 573.260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive...

  17. 21 CFR 573.260 - Calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Calcium silicate. 573.260 Section 573.260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive...

  18. 21 CFR 573.260 - Calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Calcium silicate. 573.260 Section 573.260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive...

  19. 21 CFR 573.260 - Calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Calcium silicate. 573.260 Section 573.260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive...

  20. 21 CFR 573.260 - Calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Calcium silicate. 573.260 Section 573.260 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS FOOD ADDITIVES PERMITTED IN FEED AND DRINKING WATER OF ANIMALS Food Additive...

  1. Dynamic Fatigue of a Titanium Silicate Glass

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis S.; Nettles, Alan T.; Cagle, Holly A.; Smith, W. Scott (Technical Monitor)

    2002-01-01

    A dynamic fatigue study was performed on a Titanium Silicate Glass in order to assess its susceptibility to delayed failure. Fracture mechanics techniques were used to analyze the results for the purpose of making lifetime predictions for optical elements made from this material. The material has reasonably good resistance (N=23 to stress corrosion in ambient conditions).

  2. Chemically bonded phospho-silicate ceramics

    DOEpatents

    Wagh, Arun S.; Jeong, Seung Y.; Lohan, Dirk; Elizabeth, Anne

    2003-01-01

    A chemically bonded phospho-silicate ceramic formed by chemically reacting a monovalent alkali metal phosphate (or ammonium hydrogen phosphate) and a sparsely soluble oxide, with a sparsely soluble silicate in an aqueous solution. The monovalent alkali metal phosphate (or ammonium hydrogen phosphate) and sparsely soluble oxide are both in powder form and combined in a stochiometric molar ratio range of (0.5-1.5):1 to form a binder powder. Similarly, the sparsely soluble silicate is also in powder form and mixed with the binder powder to form a mixture. Water is added to the mixture to form a slurry. The water comprises 50% by weight of the powder mixture in said slurry. The slurry is allowed to harden. The resulting chemically bonded phospho-silicate ceramic exhibits high flexural strength, high compression strength, low porosity and permeability to water, has a definable and bio-compatible chemical composition, and is readily and easily colored to almost any desired shade or hue.

  3. Lithium Manganese Silicate Positive Electrode Material

    NASA Astrophysics Data System (ADS)

    Yang, Qiong

    As the fast development of the electronic portable devices and drastic fading of fossil energy sources. The need for portable secondary energy sources is increasingly urgent. As a result, lithium ion batteries are being investigated intensely to meet the performance requirements. Among various electrode materials, the most expensive and capacity limiting component is the positive materials. Based on this, researches have been mostly focused on the development of novel cathode materials with high capacity and energy density and the lithium transition metal orthosilicates have been identified as possible high performance cathodes. Here in, we report the synthesis of a kind of lithium transition metal orthosilicates electrode lithium manganese silicate. Lithium manganese silicate has the advantage of high theoretical capacity, low cost raw material and safety. In this thesis, lithium manganese silicate are prepared using different silicon sources. The structure of silicon sources preferred are examined. Nonionic block copolymers surfactant, P123, is tried as carbon source and mophology directing agent. Lithium manganese silicate's performances are improved by adding P123.

  4. Dopant penetration studies through Hf silicate

    NASA Astrophysics Data System (ADS)

    Quevedo-Lopez, M. A.; Visokay, M. R.; Chambers, J. J.; Bevan, M. J.; LiFatou, A.; Colombo, L.; Kim, M. J.; Gnade, B. E.; Wallace, R. M.

    2005-02-01

    We present a study of the penetration of B, P, and As through Hf silicate (HfSixOy) and the effect of N incorporation in Hf silicate (HfSixOyNz) on dopant penetration from doped polycrystalline silicon capping layers. The extent of penetration through Hf silicate was found to be dependent upon the thermal annealing budget for each dopant investigated as follows: B(T⩾950°C/60s), P(T⩾1000°C/20s), and As (T⩾1050°C/60s). We propose that the enhanced diffusion observed for these dopants in HfSixOy, compared with that of SiO2 films, is related to grain boundary formation resulting from HfSixOy film crystallization. We also find that, as in the case of SiO2, N incorporation inhibits dopant (B, P, and As) diffusion through the Hf silicate and thus penetration into the underlying Si substrate. Only B penetration is clearly observed through HfSiON films for anneals at 1050 °C for durations of 10 s or longer. The calculated B diffusivity through the HfSixOyNz layer is D0=5.2×10-15cm2/s.

  5. Development of a reliable analytical method for liquid anion-exchange extraction and separation of neodymium(III).

    PubMed

    Kokare, Balasaheb N; Kamble, Ganesh S; Sargar, Balasaheb M; Anuse, Mansing A

    2012-01-01

    The liquid-liquid extraction of neodymium(III) from succinate media (0.06 M) has been studied at pH 6.0 with the solution of 0.1 M of N-n-octylaniline in xylene when equilibrium is maintained for 5 min. The back-extraction of neodymium(III) has been performed by using 0.1 M HClO₄. The effect of various parameters, such as pH, equilibrium time, extractant concentration, stripping agents, organic diluents, and aqueous to organic volume ratio on the extraction of neodymium(III) has been studied. On the basis of slope analysis, the stoichiometry of the extracted species was determined as 1 : 1 : 2 [RR'NH₂⁺Nd(succinate)₂⁻](org). The method is free from interference of large number cations and anions. The method was used for the selective extraction of neodymium(III) from its binary mixture with U(VI), Zr(IV), Nb(V), La(III), Th(IV), Ce(IV), and Y(III). The proposed method is selective and was successfully applied to the synthetic mixtures to show the practical utility of the extractant.

  6. Development of a Reliable Analytical Method for Liquid Anion-Exchange Extraction and Separation of Neodymium(III)

    PubMed Central

    Kokare, Balasaheb N.; Kamble, Ganesh S.; Sargar, Balasaheb M.; Anuse, Mansing A.

    2012-01-01

    The liquid-liquid extraction of neodymium(III) from succinate media (0.06 M) has been studied at pH 6.0 with the solution of 0.1 M of N-n-octylaniline in xylene when equilibrium is maintained for 5 min. The back-extraction of neodymium(III) has been performed by using 0.1 M HClO4. The effect of various parameters, such as pH, equilibrium time, extractant concentration, stripping agents, organic diluents, and aqueous to organic volume ratio on the extraction of neodymium(III) has been studied. On the basis of slope analysis, the stoichiometry of the extracted species was determined as 1 : 1 : 2 [RR′NH2+Nd(succinate)2−](org). The method is free from interference of large number cations and anions. The method was used for the selective extraction of neodymium(III) from its binary mixture with U(VI), Zr(IV), Nb(V), La(III), Th(IV), Ce(IV), and Y(III). The proposed method is selective and was successfully applied to the synthetic mixtures to show the practical utility of the extractant. PMID:22701373

  7. Thermoset polymer-layered silicic acid nanocomposites

    NASA Astrophysics Data System (ADS)

    Wang, Zhen

    Nanocomposites are formed when phase mixing occurs on a nanometer length scale. Due to the improved phase morphology and interfacial properties, nanocomposites exhibit mechanical properties superior to conventional composites. Toyota researchers first demonstrated that organoclay could be exfoliated in a nylon-6 matrix to greatly improve the thermal and mechanical properties of the polymer, which has resulted in a practical application in the automobile industry. A great deal of research has been conducted on organic-inorganic hybrid composites in which smectite clays are used as reinforcement agents. However, little work has been devoted to derivatives of other layered inorganic solids. In the present work, the first examples of organic polymer-layered silicic acid nanocomposites have been prepared by formation of a cured epoxy polymer network in the presence of organo cation exchange forms of magadiite. The exfoliation of silicate nanolayers in the epoxy matrix was achieved by in-situ intragallery polymerization during the thermosetting process. In general, the tensile properties, solvent resistance, barrier properties and chemical stability of the polymer matrix are greatly improved by the embedded silicate nanolayers when the matrix is flexible (sub-ambient Tg). The improvement of properties are dependent on the silicate loading, the degree of nanolayer separation and interfacial properties. Interestingly, the exfoliation also affects the polymer elasticity in a favorable way. The mechanism leading to nanocomposite formation is proposed. One exfoliated epoxy-magadiite nanocomposite/composition possessed unique transparent optical properties. The exfoliation chemistry was successfully extended to the other members of the layered silicic acid family. A new approach also was developed to prepare thermoset epoxy polymer-layered silicate nanocomposites in which curing agents can be directly intercalated into the intragallery without the need for alkylammonium ions

  8. High chloride content calcium silicate glasses.

    PubMed

    Chen, Xiaojing; Karpukhina, Natalia; Brauer, Delia S; Hill, Robert G

    2017-03-08

    Chloride is known to volatilize from silicate glass melts and until now, only a limited number of studies on oxychloride silicate glasses have been reported. In this paper we have synthesized silicate glasses that retain large amounts of CaCl2. The CaCl2 has been added to the calcium metasilicate composition (CaO·SiO2). Glasses were produced via a melt quench route and an average of 70% of the chloride was retained after melting. Up to 31.6 mol% CaCl2 has been successfully incorporated into these silicate glasses without the occurrence of crystallization. (29)Si MAS-NMR spectra showed the silicon being present mainly as a Q(2) silicate species. This suggests that chloride formed Cl-Ca(n) species, rather than Si-Cl bonds. Upon increasing the CaCl2 content, the Tg reduced markedly from 782 °C to 370 °C. Glass density and glass crystallization temperature decreased linearly with an increase in the CaCl2 content. However, both linear regressions revealed a breakpoint at a CaCl2 content just below 20 mol%. This might be attributed to a significant change in the structure and is also correlated with the nature of the crystallizing phases formed upon heat treatment. The glasses with less than 19.2 mol% CaCl2 crystallized to wollastonite, whilst the compositions with CaCl2 content equal to or greater than 19.2 mol% are thought to crystallize to CaCl2. In practice, the crystallization of CaCl2 could not occur until the crystallization temperature fell below the melting point of CaCl2. The implications of the results along with the high chloride retention are discussed.

  9. Grain Growth and Silicates in Dense Clouds

    NASA Technical Reports Server (NTRS)

    Pendeleton, Yvonne J.; Chiar, J. E.; Ennico, K.; Boogert, A.; Greene, T.; Knez, C.; Lada, C.; Roellig, T.; Tielens, A.; Werner, M.; Whittet, D.

    2006-01-01

    Interstellar silicates are likely to be a part of all grains responsible for visual extinction (Av) in the diffuse interstellar medium (ISM) and dense clouds. A correlation between Av and the depth of the 9.7 micron silicate feature (measured as optical depth, tau(9.7)) is expected if the dust species are well 'mixed. In the di&se ISM, such a correlation is observed for lines of sight in the solar neighborhood. A previous study of the silicate absorption feature in the Taurus dark cloud showed a tendency for the correlation to break down at high Av (Whittet et al. 1988, MNRAS, 233,321), but the scatter was large. We have acquired Spitzer Infrared Spectrograph data of several lines of sight in the IC 5 146, Barnard 68, Chameleon I and Serpens dense clouds. Our data set spans an Av range between 2 and 35 magnitudes. All lines of sight show the 9.7 micron silicate feature. The Serpens data appear to follow the diffuse ISM correlation line whereas the data for the other clouds show a non-linear correlation between the depth of the silicate feature relative to Av, much like the trend observed in the Taurus data. In fact, it appears that for visual extinctions greater than about 10 mag, tau(9.7) begins to level off. This decrease in the growth of the depth of the 9.7 micron feature with increasing Av could indicate the effects of grain growth in dense clouds. In this poster, we explore the possibility that grain growth causes an increase in opacity (Av) without causing a corresponding increase in tau(9.7).

  10. Silicate Dust in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Xie, Yanxia; Li, Aigen; Hao, Lei

    2017-01-01

    The unification theory of active galactic nuclei (AGNs) hypothesizes that all AGNs are surrounded by an anisotropic dust torus and are essentially the same objects but viewed from different angles. However, little is known about the dust that plays a central role in the unification theory. There are suggestions that the AGN dust extinction law appreciably differs from that of the Galaxy. Also, the silicate emission features observed in type 1 AGNs appear anomalous (i.e., their peak wavelengths and widths differ considerably from that of the Galaxy). In this work, we explore the dust properties of 147 AGNs of various types at redshifts z≲ 0.5, with special attention paid to 93 AGNs that exhibit the 9.7 and 18 μm silicate emission features. We model their silicate emission spectra obtained with the Infrared Spectrograph aboard the Spitzer Space Telescope. We find that 60/93 of the observed spectra can be well explained with “astronomical silicate,” while the remaining sources favor amorphous olivine or pyroxene. Most notably, all sources require the dust to be micron-sized (with a typical size of ∼1.5 ± 0.1 μm), much larger than submicron-sized Galactic interstellar grains, implying a flat or “gray” extinction law for AGNs. We also find that, while the 9.7 μm emission feature arises predominantly from warm silicate dust of temperature T ∼ 270 K, the ∼5–8 μm continuum emission is mostly from carbon dust of T ∼ 640 K. Finally, the correlations between the dust properties (e.g., mass, temperature) and the AGN properties (e.g., luminosity, black hole mass) have also been investigated.

  11. 40 CFR 721.9513 - Modified magnesium silicate polymer (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Modified magnesium silicate polymer... Specific Chemical Substances § 721.9513 Modified magnesium silicate polymer (generic). (a) Chemical... as modified magnesium silicate polymer (PMN P-98-604) is subject to reporting under this section...

  12. 40 CFR 721.9513 - Modified magnesium silicate polymer (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Modified magnesium silicate polymer... Specific Chemical Substances § 721.9513 Modified magnesium silicate polymer (generic). (a) Chemical... as modified magnesium silicate polymer (PMN P-98-604) is subject to reporting under this section...

  13. 40 CFR 721.9513 - Modified magnesium silicate polymer (generic).

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 40 Protection of Environment 32 2012-07-01 2012-07-01 false Modified magnesium silicate polymer... Specific Chemical Substances § 721.9513 Modified magnesium silicate polymer (generic). (a) Chemical... as modified magnesium silicate polymer (PMN P-98-604) is subject to reporting under this section...

  14. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 6 2014-04-01 2014-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c...

  15. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Aluminum calcium silicate. 182.2122 Section 182...) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Anticaking Agents § 182.2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c) Limitations, restrictions, or explanation. This...

  16. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c...

  17. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c...

  18. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c...

  19. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c...

  20. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c...

  1. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c...

  2. 21 CFR 582.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Aluminum calcium silicate. 582.2122 Section 582.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c...

  3. 21 CFR 182.2122 - Aluminum calcium silicate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Aluminum calcium silicate. 182.2122 Section 182.2122 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED....2122 Aluminum calcium silicate. (a) Product. Aluminum calcium silicate. (b) Tolerance. 2 percent. (c...

  4. 40 CFR 721.9513 - Modified magnesium silicate polymer (generic).

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 40 Protection of Environment 30 2010-07-01 2010-07-01 false Modified magnesium silicate polymer... Specific Chemical Substances § 721.9513 Modified magnesium silicate polymer (generic). (a) Chemical... as modified magnesium silicate polymer (PMN P-98-604) is subject to reporting under this section...

  5. 40 CFR 721.9513 - Modified magnesium silicate polymer (generic).

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 40 Protection of Environment 31 2011-07-01 2011-07-01 false Modified magnesium silicate polymer... Specific Chemical Substances § 721.9513 Modified magnesium silicate polymer (generic). (a) Chemical... as modified magnesium silicate polymer (PMN P-98-604) is subject to reporting under this section...

  6. 40 CFR 721.10495 - Metal silicate (generic).

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 40 Protection of Environment 32 2013-07-01 2013-07-01 false Metal silicate (generic). 721.10495... Substances § 721.10495 Metal silicate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as metal silicate (PMN P-05-634) is subject...

  7. 40 CFR 721.10495 - Metal silicate (generic).

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 31 2014-07-01 2014-07-01 false Metal silicate (generic). 721.10495... Substances § 721.10495 Metal silicate (generic). (a) Chemical substance and significant new uses subject to reporting. (1) The chemical substance identified generically as metal silicate (PMN P-05-634) is subject...

  8. Amorphous Silicates in Primitive Meteoritic Materials: Acfer 094 and IDPs

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Nakamura-Messenger, K.; Messenger, S.; Walker, Robert M.

    2009-01-01

    The abundance of presolar grains is one measure of the primitive nature of meteoritic materials. Presolar silicates are abundant in meteorites whose matrices are dominated by amorphous silicates such as the unique carbonaceous chondrite Acfer 094. Presolar silicates are even more abundant in chondritic-porous interplanetary dust particles (CP-IDPs). Amorphous silicates in the form of GEMS (glass with embedded metal and sulfides) grains are a major component of CP IDPs. We are studying amorphous silicates in Acfer 094 matrix in order to determine whether they are related to the GEMS grains in CPIDPs

  9. Characterizing Amorphous Silicates in Extraterrestrial Materials

    NASA Astrophysics Data System (ADS)

    Fu, X.; Wang, A.; Krawczynski, M. J.

    2015-12-01

    Amorphous silicates are common in extraterrestrial materials. They are seen in the matrix of carbonaceous chondrites as well as in planetary materials. Tagish Lake is one of the most primitive carbonaceous meteorites in which TEM and XRD analyses found evidence for poorly crystalline phyllosilicate-like species; Raman spectra revealed amorphous silicates with variable degree of polymerization and low crystallinity. On Mars, CheMin discovered amorphous phases in all analyzed samples, and poorly crystalline smectite in mudstone samples. These discoveries pose questions on the crystallinity of phyllosilicates found by remote sensing on Mars, which is directly relevant to aqueous alteration during geologic history of Mars. Our goal is to use spectroscopy to better characterize amorphous silicates. We use three approaches: (1) using silicate glasses synthesized with controlled chemistry to study the effects of silicate polymerization and (2) using phyllosilicates synthesized with controlled hydrothermal treatment to study the effect of crystallinity on vibrational spectroscopy, finally (3) to use the developed correlations in above two steps to study amorphous phases in meteorites, and those found in future missions to Mars. In the 1st step, silicate glasses were synthesized from pure oxides in a range of NBO/T ratios (from 0 to 4). Depending on the targeted NBO/T and composition of mixed oxides, temperatures for each experiment fell in a range from 1260 to 1520 °C, run for ~ 4 hrs. The melt was quenched in liquid N2 or water. Homogeneity of glass was checked under optical microscopy. Raman spectra were taken over 100 spots on small chips free of bubbles and crystals. We have observed that accompanying an increase of NBO/T, there is a strengthening and a position shift of the Raman peak near 1000 cm-1 (Si-Onon-bridging stretching mode), and the weakening of broad Raman peaks near 500 cm-1 (ring breathing mode) and 700cm-1 (Si-Obridging-Si mode). We are building the

  10. Final report on the safety assessment of potassium silicate, sodium metasilicate, and sodium silicate.

    PubMed

    Elmore, Amy R

    2005-01-01

    Potassium Silicate, Sodium Metasilicate, and Sodium Silicate combine metal cations with silica to form inorganic salts used as corrosion inhibitors in cosmetics. Sodium Metasilicate also functions as a chelating agent and Sodium Silicate as a buffering and pH adjuster. Sodium Metasilicate is currently used in 168 formulations at concentrations ranging from 13% to 18%. Sodium Silicate is currently used in 24 formulations at concentrations ranging from 0.3% to 55%. Potassium Silicate and Sodium Silicate have been reported as being used in industrial cleaners and detergents. Sodium Metasilicate is a GRAS (generally regarded as safe) food ingredient. Aqueous solutions of Sodium Silicate species are a part of a chemical continuum of silicates based on an equilibrium of alkali, water, and silica. pH determines the solubility of silica and, together with concentration, determines the degree of polymerization. Sodium Silicate administered orally is readily absorbed from the alimentary canal and excreted in the urine. The toxicity of these silicates has been related to the molar ratio of SiO2/Na2O and the concentration being used. The Sodium Metasilicate acute oral LD50 ranged from 847 mg/kg in male rats to 1349.3 mg/kg in female rats and from 770 mg/kg in female mice to 820 mg/kg in male mice. Gross lesions of variable severity were found in the oral cavity, pharynx, esophagus, stomach, larynx, lungs, and kidneys of dogs receiving 0.25 g/kg or more of a commercial detergent containing Sodium Metasilicate; similar lesions were also seen in pigs administered the same detergent and dose. Male rats orally administered 464 mg/kg of a 20% solution containing either 2.0 or 2.4 to 1.0 ratio of sodium oxide showed no signs of toxicity, whereas doses of 1000 and 2150 mg/kg produced gasping, dypsnea, and acute depression. Dogs fed 2.4 g/kg/day of Sodium Silicate for 4 weeks had gross renal lesions but no impairment of renal function. Dermal irritation of Potassium Silicate, Sodium

  11. Defect characterization in neodymium doped thallium indium disulfide crystals by thermoluminescence measurements

    NASA Astrophysics Data System (ADS)

    Delice, S.; Gasanly, N. M.

    2016-10-01

    Characteristics of defect centers in neodymium doped TlInS2 single crystals have been investigated in virtue of thermoluminescence measurements carried out at low temperatures (10-300 K) with various heating rates between 0.4 and 1.2 K s-1. One glow peak was detected with peak maximum temperature of 26 K at a rate of 0.4 K s-1. The observed glow peak was analyzed using three points and heating rate methods. The analysis results revealed the presence of one trap level with activation energy of 14 meV. Three points method showed that mixed order of kinetic dominates the trapping level. Shift of peak maximum temperature to higher values and decrease in TL intensity were observed as the heating rate was increased progressively. Distribution of traps was demonstrated using an experimental method based on illumination temperature varying between 10 and 14 K.

  12. The durability of parylene coatings on neodymium-iron-boron magnets.

    PubMed

    Noar, J H; Wahab, A; Evans, R D; Wojcik, A G

    1999-12-01

    A parylene coating is frequently used to prevent corrosion of neodymium-iron-boron magnets when they are used intra-orally. This in vitro study was designed to test the durability of parylene coating in a simulated oral environment. Single and double parylene-coated magnets were subjected to grinding and crushing forces in an industrial ball mill. The results demonstrate that abrasion and wear was visible around the edges after 1 hour of testing, with a breach of the coating noted under high magnification scanning electron microscopy (SEM). The conclusion of the study is that parylene coating is unlikely to withstand intra-oral forces. The shape of the magnets, the manufacturing process involved in their production, and the thickness of the parylene coating are important factors to consider with respect to the durability of magnets used in the mouth.

  13. Investigation on microstructure and martensitic transformation of neodymium-added NiTi shape memory alloys

    NASA Astrophysics Data System (ADS)

    Maashaa, Dovchinvanchig; Dorj, Ulzii-Orshikh; Lee, Malrey; Lee, Min Hi; Zhao, Chunwang; Dashjav, Munguntsetseg; Woo, Seon-Mi

    2016-10-01

    The effect of rare earth element neodymium (Nd) addition on the microstructure and martensitic transformation behavior of Ni50Ti50-xNdx (x = 0, 0.1, 0.3, 0.5 and 0.7 at.%) shape memory alloy was investigated by scanning electronic microscope, X-ray diffraction and differential scanning calorimetry. The results show that the microstructure of Ni-Ti-Nd ternary alloy consists of NiNd phase, NiTi2 and the NiTi matrix. A one-step martensitic transformation is observed in the alloys. The martensitic transformation temperature Ms increases sharply increasing 0.1-0.7 at.% Nd content is added.

  14. Calf thymus DNA binding studies of the new neodymium-naproxen complex.

    PubMed

    Huo, Ruina; Xu, Guiqing; Jiang, Xiaoying; Ge, Yao; Xue, Zaikun; Cui, Fengling

    2012-05-01

    Fluorescence spectroscopy in combination with UV absorption spectroscopy was carried out to investigate the interaction between the neodymium-naproxen complex (Nd-NAP) and calf thymus DNA (ctDNA). The experimental results showed that Nd-NAP intercalated with the ctDNA base pairs. Analysis of fluorescence quenching data of Nd-NAP by ctDNA at different temperatures using a Stern-Volmer equation revealed that dynamic and static quenching occurred simultaneously. The binding constants and the number of binding sites at 293 and 310 K were obtained as 2.904 × 10(4) L mol(-1), 1.172 and 2.432 × 10(4) L mol(-1), 1.143, respectively. The thermodynamic parameters ΔG, ΔH, and ΔS calculated at different temperatures indicated that hydrogen bonding and van der Waals force were the main binding forces.

  15. Vacuum ultraviolet field emission lamp consisting of neodymium ion doped lutetium fluoride thin film as phosphor.

    PubMed

    Yanagihara, Masahiro; Tsuji, Takayuki; Yusop, Mohd Zamri; Tanemura, Masaki; Ono, Shingo; Nagami, Tomohito; Fukuda, Kentaro; Suyama, Toshihisa; Yokota, Yuui; Yanagida, Takayuki; Yoshikawa, Akira

    2014-01-01

    A vacuum ultraviolet (VUV) field emission lamp was developed by using a neodymium ion doped lutetium fluoride (Nd(3+) : LuF3) thin film as solid-state phosphor and carbon nanofiber field electron emitters. The thin film was synthesized by pulsed laser deposition and incorporated into the lamp. The cathodoluminescence spectra of the lamp showed multiple emission peaks at 180, 225, and 255 nm. These emission spectra were in good agreement with the spectra reported for the Nd(3+) : LuF3 crystal. Moreover, application of an acceleration voltage effectively increased the emission intensity. These results contribute to the performance enhancement of the lamp operating in the VUV region.

  16. Heavy metals chromium and neodymium reduced phosphorylation level of heat shock protein 27 in human keratinocytes.

    PubMed

    Zhang, Qihao; Zhang, Lei; Xiao, Xue; Su, Zhijian; Zou, Ping; Hu, Hao; Huang, Yadong; He, Qing-Yu

    2010-06-01

    Heavy metals may exert their acute and chronic effects on the human skin through stress signals. In the present study, 2DE-based proteomics was used to analyze the protein expression in human keratinocytes exposed to heavy metals, chromium and neodymium, and 10 proteins with altered expression were identified. Among these proteins, small heat shock protein 27 (HSP27) was up-regulated significantly and the up-regulation was validated by Western blot and immunofluorescence. In addition, the mRNA expression level of HSP27 markedly increased as detected by quantitative PCR. More interestingly, the ratio of phosphorylated HSP27 and total HSP27 significantly decreased in keratinocytes treated with the heavy metals. These findings suggested that heavy metals reduced the phosphorylation level of HSP27, and that the ratio of p-HSP27 and HSP27 may represent a potential marker or additional endpoint for the hazard assessment of skin irritation caused by chemical products.

  17. The effect of popcorn and carbonization on neodymium: YAG laser dosimetry in the canine model.

    PubMed

    Perlmutter, A P; Vargas, J C; Muschter, R

    1995-01-01

    Neodymium:YAG laser irradiation of the canine prostate provides an experimental model for the study of the laser-tissue interaction in laser prostatectomy. Prostate irradiation was undertaken using right-angle-firing laser fibers through an open suprapubic cystotomy, and the procedure was monitored by video endoscopy via a perineal urethrostomy. The effects of popcorn and surface carbonization on intraprostatic heating profiles were determined by interstitial thermometry. We found that popcorn reduced intraprostatic temperatures but that continued irradiation resulted in the restoration of heating. Carbonization resulted in the loss of heating ability deep in the prostate. These observations allow the urologist to understand the thermal implications of observed surface change and to modify lasing parameters during surgery to obtain the desired laser-tissue interaction.

  18. Extraction chromatography of neodymium by an organophosphorous extractant supported on various polymeric resins

    SciTech Connect

    Takigawa, D.Y.

    1993-04-01

    Fifteen resins coated with dihexyl-N,N-diethylcarbamoylmethyl phosphonate (CMP) were studied for their extraction of neodymium (Nd) in 4.0 and 7.0 M nitric acid. Resin properties, such as chemical composition and physical morphology, which can influence Nd extraction as well as subsequent resin regeneration (Nd stripping), were identified. Hydrophilic or polar resins coated with CMP efficiently extracted the Nd. Resins initially washed free of residual monomer and solvent before CMP coating outperformed their untreated counterparts. The macroporous styrene-divinylbenzene hydrophobic resins that were high in surface area were less effective supports compared with hydrophilic microporous Aurorez, polybenzimidazole (PBI) and macroporous Amberlite polyacrylic resins. Only one resin, Duolite C-467, showed no measurable improvement in Nd extraction with CMP coating. CMP-coated Aurorez PBI, a microporous and hydrophilic polymeric resin with an average surface area, showed the best overall efficiency for Nd removal and resin regeneration.

  19. Bleb reduction using combined photodisruptive and photocoagulative neodymium-doped yttrium-aluminum-garnet laser.

    PubMed

    Kumar, Harsh; Dangda, Sonal

    2016-12-01

    This case report aims to highlight the role of photodisruptive neodymium-doped yttrium-aluminum-garnet (Nd:YAG) (1064 nm) laser in the treatment of bleb dysesthesia, which occurs in overhanging blebs or with perilimbal spread. Although treatment of such dysesthetic blebs with laser photocoagulation has been previously described, cases where the height of bleb precludes laser penetration, desired effect might not be seen. We herein describe a technique using a combination of photocoagulative (532 nm) and photodisruptive (1064 nm) Nd:YAG laser for a high bleb migrating nasally and inferiorly along the limbus in a 64-year-old female, causing hypotony and consequent macular edema. Successful reduction could be achieved within a week of treatment. By 6 weeks, intraocular pressure improved to 8 mmHg, macular edema subsided, and visual acuity improved to 6/6. Although surgical procedures to correct bleb dysesthesia are available, laser procedures being quick outpatient modalities are more comfortable for the patients.

  20. Optical Properties of Neodymium Oxide Nanoparticle-Doped Polyvinyl Alcohol Film

    NASA Astrophysics Data System (ADS)

    Keikhaei, Mansoureh; Motevalizadeh, Leili; Attaran-Kakhki, Ebrahim

    2016-04-01

    The structural and optical characteristics of polyvinyl alcohol (PVA) doped with different concentration of Nd2O3 nanoparticles to use an active media for polymer laser were studied. The PVA polymer was considered as the host and Nd2O3 nanoparticles as the active element. The media as a thin film was prepared using spin coating technique. Structural properties of layers were investigated by X-ray diffraction (XRD) pattern and atomic force microscope (AFM) technique. The effect of the concentrations of the neodymium source on the optical properties of Nd2O3/PVA thin films was investigated through UV-Vis absorption spectroscopy and their optical band gap was evaluated. Also, the FTIR and fluorescence spectra of the samples were detected. The fluorescence spectra of films showed that the maximum wavelength occurred at 568nm with no significant shift.

  1. Influence of the neodymium glass parameters on the amplified spontaneous emission in slab amplifier

    NASA Astrophysics Data System (ADS)

    Wang, Bingyan; Zhang, Junyong; Zhang, Yanli; Wang, Li; Zhu, Jianqiang

    2015-02-01

    Amplified spontaneous emission (ASE) causes the decrease of the inverted population density and the nonuniformity of gain in slab amplifier for high power laser systems. In this paper, a three dimension model, based on the data in SG-II, in which the residual reflection in the cladding and the ASE process are taken into consideration, is built to analyze the space distribution and time evolution of small signal gain coefficient using Monte Carlo algorithm and ray tracing. This model has been verified by comparing with the experimental data. The traverse size of slab is 68.2cm×36.3cm, which is usually decided by the clear aperture and the manufacture. By means of the model, the impact of thickness, residual reflectivity and the stimulated cross section of neodymium glass to the ASE are analyzed in detail.

  2. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    NASA Astrophysics Data System (ADS)

    Podhorodecki, A.; Banski, M.; Misiewicz, J.; Lecerf, C.; Marie, P.; Cardin, J.; Portier, X.

    2010-09-01

    Gallium oxide and more particularly β-Ga2O3 matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samples that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.

  3. Influence of neodymium concentration on excitation and emission properties of Nd doped gallium oxide nanocrystalline films

    SciTech Connect

    Podhorodecki, A.; Banski, M.; Misiewicz, J.; Lecerf, C.; Marie, P.; Cardin, J.; Portier, X.

    2010-09-15

    Gallium oxide and more particularly {beta}-Ga{sub 2}O{sub 3} matrix is an excellent material for new generation of devices electrically or optically driven as it is known as the widest band gap transparent conductive oxide. In this paper, the optical properties of neodymium doped gallium oxide films grown by magnetron sputtering have been analyzed. The influence of the Nd ions concentration on the excitation/emission mechanisms of Nd ions and the role of gallium oxide matrix have been investigated. The grain size reduction into gallium oxide films have been observed when concentration of Nd increases. It has been found for all samples that the charge transfer is the main excitation mechanism for Nd ions where defect states play an important role as intermediate states. As a consequence Nd emission efficiency increases with temperature giving rise to most intensive emission at 1087 nm at room temperature.

  4. Vacuum Ultraviolet Field Emission Lamp Consisting of Neodymium Ion Doped Lutetium Fluoride Thin Film as Phosphor

    PubMed Central

    Yanagihara, Masahiro; Tsuji, Takayuki; Yusop, Mohd Zamri; Tanemura, Masaki; Nagami, Tomohito; Fukuda, Kentaro; Suyama, Toshihisa; Yokota, Yuui; Yanagida, Takayuki; Yoshikawa, Akira

    2014-01-01

    A vacuum ultraviolet (VUV) field emission lamp was developed by using a neodymium ion doped lutetium fluoride (Nd3+ : LuF3) thin film as solid-state phosphor and carbon nanofiber field electron emitters. The thin film was synthesized by pulsed laser deposition and incorporated into the lamp. The cathodoluminescence spectra of the lamp showed multiple emission peaks at 180, 225, and 255 nm. These emission spectra were in good agreement with the spectra reported for the Nd3+ : LuF3 crystal. Moreover, application of an acceleration voltage effectively increased the emission intensity. These results contribute to the performance enhancement of the lamp operating in the VUV region. PMID:25302320

  5. Current status and future outlook for bonded neodymium permanent magnets (invited)

    NASA Astrophysics Data System (ADS)

    Croat, J. J.

    1997-04-01

    Bonded neodymium magnets can provide significant size and weight reduction and/or performance enhancement over sintered and, particularly, bonded ferrite permanent magnets and, moreover, provide these benefits at reasonable cost. Primarily for these reasons, these bonded magnets are now used in a wide and growing range of computer peripheral, office automation, and consumer electronic applications and now constitute the fastest growing segment of the permanent magnet market. The current status of these materials will be reviewed. Included is a brief overview of the manufacture of these magnetically isotropic magnets and a discussion of their unique properties and features from the perspective of both bonded magnet producer and user. Major applications are discussed as are some of the factors that will drive the market for these materials in the future. New technical developments, including the status and outlook for anisotropic bonded materials, high remanance isotropic materials and high temperature bonded magnets will also be discussed.

  6. High-energy neodymium laser radiation for the treatment of face cutaneous melanoma.

    PubMed

    Moskalik, K G; Kozlov, A P; Demin, E V

    2010-01-01

    This study retrospectively evaluated the curative efficacy of two powerful pulsed Neodymium (Nd) lasers (lambda = 1060 nm, pulse duration 1 and 4.5 msec, maximum pulse energy 700 and 1000 J, respectively) for the treatment of 47 patients with histologically confirmed stage I cutaneous melanoma of the face who were followed-up 5 years and more. The estimated 5-year survival rate was 82.9%. Regional and distant metastases developed in 23.4% of the patients. There were no cases with local recurrences. High-energy pulsed Nd laser radiation is effective in treating flat and / or slightly raised cutaneous stage I facial melanomas, while the therapeutic result is also accompanied by positive cosmetic result.

  7. Ultralow compressibility silicate without highly coordinated silicon.

    PubMed

    Scott, Henry P; Williams, Quentin; Knittle, Elise

    2002-01-07

    The bulk modulus of scheelite-structured ZrSiO(4) is 301.4+/-12.5 GPa, as derived from static compression experiments to 52.5 GPa. It is as stiff as the most incompressible known silicate, SiO(2) stishovite. This high incompressibility indicates that octahedrally coordinated silicon is not required to generate ultrastiff silicates: ZrSiO(4) scheelite is the most incompressible material containing SiO(4) tetrahedra. Its incompressibility is in accord with a semitheoretical relation we derive for the bulk modulus of scheelite-structured materials. Based upon correlations between incompressibility and hardness, scheelite-structured oxides may thus represent a new family of ultrahard materials.

  8. Tailored Nanocomposites of Polypropylene with Layered Silicates

    SciTech Connect

    Xu, L.; Nakajima, H; Manias, E; Krishnamoorti, R

    2009-01-01

    The melt rheological properties of layered silicate nanocomposites with maleic anhydride (MA) functionalized polypropylene are contrasted to those based on ammonium-terminated polypropylene. While the MA functionalized PP based nanocomposites exhibit solid-like linear viscoelastic behavior, consistent with the formation of a long-lived percolated nanoparticle network, the single-end ammonium functionalized PP based nanocomposites demonstrated liquid-like behavior at comparable montmorillonite concentrations. The differences in the linear viscoelasticity are attributed to the presence of bridging interactions in MA functionalized nanocomposites. Further, the transient shear stress of the MA functionalized nanocomposites in start-up of steady shear is a function of the shear strain alone, and the steady shear response is consistent with that of non-Brownian systems. The weak dependence of the steady first normal stress difference on the steady shear stress suggests that the polymer chain mediated silicate network contributes to such unique flow behavior.

  9. Photoemission study of cerium silicate model systems

    NASA Astrophysics Data System (ADS)

    Skála, Tomáš; Matolín, Vladimír

    2013-01-01

    Interaction of silicon with cerium oxide was studied by photoelectron spectroscopy using two model systems CeOx/Si(1 1 1) and Si/CeO2(1 1 1)/Cu(1 1 1) which can be used for fundamental studies in the field of microelectronics and heterogeneous catalysis. The interaction was found to be strong and lead to a formation of cerium silicate films of the proposed stoichiometry Ce4.67Si3O13. Their maximum thickness was limited by diffusion of silicon. Beside silicate other compounds were growing on the surface - SiO2, Si2O, Si, and CeO2. The assignment of the formed species is based on the interpretation of photoemission spectra involving the measurements of various reference O/Si and Sisbnd O/Cu systems.

  10. Topological Control on Silicates' Dissolution Kinetics.

    PubMed

    Pignatelli, Isabella; Kumar, Aditya; Bauchy, Mathieu; Sant, Gaurav

    2016-05-10

    Like many others, silicate solids dissolve when placed in contact with water. In a given aqueous environment, the dissolution rate depends on the composition and the structure of the solid and can span several orders of magnitude. Although the kinetics of dissolution depends on the complexities of both the dissolving solid and the solvent, a clear understanding of which structural descriptors of the solid control its dissolution rate is lacking. By pioneering dissolution experiments and atomistic simulations, we correlate the dissolution rates-ranging over 4 orders of magnitude-of a selection of silicate glasses and crystals to the number of chemical topological constraints acting between the atoms of the dissolving solid. The number of such constraints serves as an indicator of the effective activation energy, which arises from steric effects, and prevents the network from reorganizing locally to accommodate intermediate units forming over the course of the dissolution.

  11. Neodymium in the oceans: a global database, a regional comparison and implications for palaeoceanographic research

    PubMed Central

    Griffiths, Alexander M.; Lambelet, Myriam; Little, Susan H.; Stichel, Torben; Wilson, David J.

    2016-01-01

    The neodymium (Nd) isotopic composition of seawater has been used extensively to reconstruct ocean circulation on a variety of time scales. However, dissolved neodymium concentrations and isotopes do not always behave conservatively, and quantitative deconvolution of this non-conservative component can be used to detect trace metal inputs and isotopic exchange at ocean–sediment interfaces. In order to facilitate such comparisons for historical datasets, we here provide an extended global database for Nd isotopes and concentrations in the context of hydrography and nutrients. Since 2010, combined datasets for a large range of trace elements and isotopes are collected on international GEOTRACES section cruises, alongside classical nutrient and hydrography measurements. Here, we take a first step towards exploiting these datasets by comparing high-resolution Nd sections for the western and eastern North Atlantic in the context of hydrography, nutrients and aluminium (Al) concentrations. Evaluating those data in tracer–tracer space reveals that North Atlantic seawater Nd isotopes and concentrations generally follow the patterns of advection, as do Al concentrations. Deviations from water mass mixing are observed locally, associated with the addition or removal of trace metals in benthic nepheloid layers, exchange with ocean margins (i.e. boundary exchange) and/or exchange with particulate phases (i.e. reversible scavenging). We emphasize that the complexity of some of the new datasets cautions against a quantitative interpretation of individual palaeo Nd isotope records, and indicates the importance of spatial reconstructions for a more balanced approach to deciphering past ocean changes. This article is part of the themed issue ‘Biological and climatic impacts of ocean trace element chemistry’.

  12. The photocatalytic and antibacterial activities of neodymium and iodine doped TiO(2) nanoparticles.

    PubMed

    Jiang, Xuefeng; Yang, Lu; Liu, Peng; Li, Xi; Shen, Jian

    2010-08-01

    A series of photocatalysts were synthesized by neodymium and iodine doped TiO(2). The characteristics of neodymium and iodine doped TiO(2) were evaluated by X-ray diffraction (XRD), UV-vis diffuse reflectance spectra, and scanning electronic microscope (SEM). In the synthesis process, Nd:I:TiO(2) with different doping content (molar ratios) calcined at different temperature was designed. After the photocatalysts were synthesized under different condition, they were compared with each other by photocatalytic degradation of methylene blue (MB). The most efficient catalyst to degrade MB was Nd combined with I doped TiO(2) with molar ratio of 5:10:100 calcined at 400 degrees C. It is anatase crystal and the average size of crystallites was about 6.0 nm. It has absorption spectrometry in the visible light range of 400-550 nm. In addition, compared with pure TiO(2), the doped catalyst also has intense absorption at 528, 587, 683, 750, 808, and 881 nm. The catalytic efficiency was tested by monitoring the photocatalytic degradation, and detriment of MB and bovine serum albumin (BSA). The antibacterial activities were studied by Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The results showed that the optimum doping contents was Nd:I:TiO(2)=5:10:100 (molar ratio) calcined at 400 degrees C, and the synthesized catalyst could inhibit E. coli and S. aureus through damaging their outer membrane (even deteriorated completely) by the irradiation of visible light.

  13. Neodymium in the oceans: a global database, a regional comparison and implications for palaeoceanographic research

    NASA Astrophysics Data System (ADS)

    van de Flierdt, Tina; Griffiths, Alexander M.; Lambelet, Myriam; Little, Susan H.; Stichel, Torben; Wilson, David J.

    2016-11-01

    The neodymium (Nd) isotopic composition of seawater has been used extensively to reconstruct ocean circulation on a variety of time scales. However, dissolved neodymium concentrations and isotopes do not always behave conservatively, and quantitative deconvolution of this non-conservative component can be used to detect trace metal inputs and isotopic exchange at ocean-sediment interfaces. In order to facilitate such comparisons for historical datasets, we here provide an extended global database for Nd isotopes and concentrations in the context of hydrography and nutrients. Since 2010, combined datasets for a large range of trace elements and isotopes are collected on international GEOTRACES section cruises, alongside classical nutrient and hydrography measurements. Here, we take a first step towards exploiting these datasets by comparing high-resolution Nd sections for the western and eastern North Atlantic in the context of hydrography, nutrients and aluminium (Al) concentrations. Evaluating those data in tracer-tracer space reveals that North Atlantic seawater Nd isotopes and concentrations generally follow the patterns of advection, as do Al concentrations. Deviations from water mass mixing are observed locally, associated with the addition or removal of trace metals in benthic nepheloid layers, exchange with ocean margins (i.e. boundary exchange) and/or exchange with particulate phases (i.e. reversible scavenging). We emphasize that the complexity of some of the new datasets cautions against a quantitative interpretation of individual palaeo Nd isotope records, and indicates the importance of spatial reconstructions for a more balanced approach to deciphering past ocean changes. This article is part of the themed issue 'Biological and climatic impacts of ocean trace element chemistry'.

  14. Effect of corrosion products (neodymium iron boron) on oral fibroblast proliferation.

    PubMed

    Evans, R D; McDonald, F

    1995-01-01

    The biological effects of the corrosion products of neodymium iron boron (Nd2Fe14B) magnets are largely unknown. The aim of this study was to identify the types of corrosion product and to evaluate the effect of the corrosion products (CP) of Nd2Fe14B magnets on the proliferation of human oral mucosal fibroblasts. Uncoated Nd2Fe14B magnets were stored in saline at 37 degrees C for 6 months and the corrosion products collected. 100 microL of a cell suspension (human oral mucosal fibroblasts [14 x 10(4) cells/mL]) was aliquoted into 72 wells of a 96-well plate, the remaining plates receiving culture medium only. After 12 h incubation at 37 degrees C, each well then received 100 microL of either (A) culture medium, (B) 100% CP, (C) 50% CP, or (D) 0% CP. The plates were reincubated at 37 degrees C for a further 48, 96, or 144 h. Fibroblast proliferation was assessed using the methylene blue uptake/elution technique. The compounds in the corrosion product were examined using quantitative X-ray analysis. Statistical analysis (ANOVA, Bonferroni's test 0.05, SAS v 6.04), showed that at each time point, the cell numbers in groups B, C, and D were significantly lower than group A. Within groups B, C, and D no significant differences were found, despite the suggestion of a dose response effect. Fibroblast proliferation in the presence of corrosion products was significantly lower than with culture medium. Fibroblast proliferation did occur in the presence of 0, 50, and 100% CP. The actual corrosion products appeared to be salts of iron but 3.2% (+/- 0.6) of neodymium chloride (NdCl3) was found.

  15. Neodymium isotopic characterization of Ross Sea Bottom Water and its advection through the southern South Pacific

    NASA Astrophysics Data System (ADS)

    Basak, Chandranath; Pahnke, Katharina; Frank, Martin; Lamy, Frank; Gersonde, Rainer

    2015-06-01

    Since the inception of the international GEOTRACES program, studies investigating the distribution of trace elements and their isotopes in the global ocean have significantly increased. In spite of this large-scale effort, the distribution of neodymium isotopes (143Nd/144Nd, εNd) and concentrations ([Nd]) in the high latitude South Pacific is still understudied, specifically north of the Antarctic Polar Front (APF). Here we report dissolved Nd isotopes and concentrations from 11 vertical water column profiles from the South Pacific between South America and New Zealand and across the Antarctic frontal system. Results confirm that Ross Sea Bottom Water (RSBW) is represented by an εNd value of ∼ - 7, and for the first time show that these Nd characteristics can be traced into the Southeast Pacific until progressive mixing with ambient Lower Circumpolar Deep Water (LCDW) dilutes this signal north of the APF. That is, εNd behaves conservatively in RSBW, opening a path for studies of past RSBW behavior. Neodymium concentrations show low surface concentrations and a linear increase with depth north of the APF. South of the APF, surface [Nd] is high and increases with depth but remains almost constant below ∼1000 m. This vertical and spatial [Nd] pattern follows the southward shoaling density surfaces of the Southern Ocean and hence suggests supply of Nd to the upper ocean through upwelling of Nd-rich deep water. Low particle abundance due to reduced opal production and seasonal sea ice cover likely contributes to the maintenance of the high upper ocean [Nd] south of the APF. This suggests a dominant lateral transport component on [Nd] and a reduced vertical control on Nd concentrations in the South Pacific south of the APF.

  16. Concentrations and isotopic compositions of neodymium in the eastern Indian Ocean and Indonesian straits

    NASA Astrophysics Data System (ADS)

    Jeandel, Catherine; Thouron, Danièle; Fieux, Michèle

    1998-08-01

    Four profiles of Nd concentration and isotopic composition were determined at two stations in the eastern Indian Ocean along a north/south section between Bali and Port-Hedland and at two others in the Timor and Sumba straits. Neodymium concentrations increase with depth, between 7.2 pmol/L at the surface to 41.7 pmol/L close to the bottom. The ɛ Nd of the different water masses along the section are -7.2 ± 0.2 for the Indian Bottom Waters and -6.1 ± 0.2 for the Indian Deep Waters. The intermediate and thermocline waters are less radiogenic at st-10 than at st-20 (-5.3 ± 0.3 and -3.6 ± 0.2, respectively). In the Timor Passage and Sumba Strait, ɛ Nd of the Indonesian waters is -4.1 ± 0.2 and that of the North Indian Intermediate Waters is -2.6 ± 0.3. These distinct isotopic signals constrain the origins of the different water masses sampled in the eastern Indian Ocean. They fix the limit of the nonradiogenic Antarctic and Indian contributions to the southern part of the section whereas the northern part is influenced by radiogenic Indonesian flows. In addition, the neodymium isotopic composition suggests that in the north, deep waters are influenced by a radiogenic component originating from the Sunda Arch Slope flowing deeper than 1200 m, which was not documented previously. Mixing calculations assess the conservativity of ɛ Nd on the scale of an oceanic basin. The origin of the surprising radiogenic signal of the NIIW is discussed and could result from a remobilization of Nd sediment-hosted on the Java shelf, requiring important dissolved/particulate exchange processes. Such processes, occurring in specific areas, could play an important role in the world ocean Nd budget.

  17. Biodegradable Polyester/Layered Silicate Nanocomposites

    DTIC Science & Technology

    2003-01-01

    compatible with the polymer [5-9]. In this paper we report the synthesis and properties of both PLA and PHB nanocomposites with different nanoclays...hydroxy polyester, polylactide (PLA) and fl-hydroxy polyester, polyhydroxybutyrate ( PHB ) with layered silicates have been successfully prepared by melt...extrusion of PLA and PHB with organically modified montmorillonite (MMT) and fluoromica. The mechanical properties of the nanocomposites are improved

  18. Polymorphism in silicate-postperovskite reviewed (Invited)

    NASA Astrophysics Data System (ADS)

    Tschauner, O. D.

    2010-12-01

    Early on in the examination of postperovskite(ppv)-type magnesium metasilicate it had been debated if this potential deep mantle mineral can be subject to further structural transformation as function of composition, pressure, and temperature within the range of conditions in the lower mantle. MgSiO3-perovskite accommodates minor elements through local lattice distortions by tilt of the corner-sharing octahedral framework. The CaIrO3-type ppv structure does not seem to possess a similar mechanism of local relaxation of lattice strain. Instead minor elements may rather be accommodated by periodic kinks in this layered structure (1). This kinking-mechanism allows for generating a plethora of polymorphs similar in structure and free energy (1,2). However, the elastic properties of ppv may be strongly affected by this type of structural modification. While structural analogues of silicate-ppv exhibit this type of polymorphism (3,4) previous attempts to examine polymorphism in silicate-ppv remained suggestive (2,5). This is mostly owed to the severe constraints imposed on powder diffraction studies conducted under the extreme conditions of stability of MgSiO3-ppv. Here I present new results on silicate-ppv based on different experimental strategies which shed more light on this complex yet important issue of structural modifications in minor-element bearing silicate-ppv. (1) Oganov et al. Nature 438, 1142 (2005);(2) Tschauner et al. Am. Min. 93, 533 (2008); (3) Shirako et al. Phys. Chem. Min. 36, 455 (2009); Yakovlev et al. J. Sol. Stat. Chem. 182, 1545 (2009) Work supported through NNSA Cooperative Agreement DOE-FC88-01NV14049

  19. Conductimetric determination of decomposition of silicate melts

    NASA Technical Reports Server (NTRS)

    Kroeger, C.; Lieck, K.

    1986-01-01

    A description of a procedure is given to detect decomposition of silicate systems in the liquid state by conductivity measurements. Onset of decomposition can be determined from the temperature curves of resistances measured on two pairs of electrodes, one above the other. Degree of decomposition can be estimated from temperature and concentration dependency of conductivity of phase boundaries. This procedure was tested with systems PbO-B2O3 and PbO-B2O3-SiO2.

  20. SILICATE EVOLUTION IN BROWN DWARF DISKS

    SciTech Connect

    Riaz, B.

    2009-08-10

    We present a compositional analysis of the 10 {mu}m silicate spectra for brown dwarf disks in the Taurus and Upper Scorpius (UppSco) star-forming regions, using archival Spitzer/Infrared Spectrograph observations. A variety in the silicate features is observed, ranging from a narrow profile with a peak at 9.8 {mu}m, to nearly flat, low-contrast features. For most objects, we find nearly equal fractions for the large-grain and crystalline mass fractions, indicating both processes to be active in these disks. The median crystalline mass fraction for the Taurus brown dwarfs is found to be 20%, a factor of {approx}2 higher than the median reported for the higher mass stars in Taurus. The large-grain mass fractions are found to increase with an increasing strength in the X-ray emission, while the opposite trend is observed for the crystalline mass fractions. A small 5% of the Taurus brown dwarfs are still found to be dominated by pristine interstellar medium-like dust, with an amorphous submicron grain mass fraction of {approx}87%. For 15% of the objects, we find a negligible large-grain mass fraction, but a >60% small amorphous silicate fraction. These may be the cases where substantial grain growth and dust sedimentation have occurred in the disks, resulting in a high fraction of amorphous submicron grains in the disk surface. Among the UppSco brown dwarfs, only usd161939 has a signal-to-noise ratio high enough to properly model its silicate spectrum. We find a 74% small amorphous grain and a {approx}26% crystalline mass fraction for this object.

  1. Neutron Diffraction Study of Silicate Perovskites

    NASA Astrophysics Data System (ADS)

    Mao, H. K.; van Orman, J.; Fei, Y.; Hemley, R. J.; Loveday, J.; Nelmes, R.; Smith, R. I.

    2002-12-01

    The oxygen deficiency and cation-site distribution of silicate perovskite control its physical and chemical properties, including density, bulk modulus, defect mobility, ionic transport, flow behavior, oxidation states, hydration, and minor-element solubility. These properties of perovskite, in turn control the geophysical and geochemical processes of the Earth. The possibility of oxygen deficiency was first recognized in perovskite with minor amounts of Al replacing Mg and Si [1, 2], and its significance is compared to the analogous defect perovskite in ceramics [3]. Basic crystallographic characteristics of the silicate perovskite, including the lattice parameters of the orthorhombic unit cell, the Pbmn space group, and atomic positions, were previously determined by x-ray diffraction [4]. The defect crystallography of silicate perovskite, however, cannot be measured by x-rays because the relevant ions (Mg2+, Al3+, Si4+ and O2-) are isoelectronic. These ions have very different neutron cross-section and can be readily resolved by neutron diffraction. Using multianvil apparatus, we synthesized perovskite samples at 1700°C and 25-28 GPa. We perform multiple runs to accumulate 3 mm3 sample each for the MgSiO3 end member and MgSiO3 plus 5 weight %\\ Al2O3 in perovskite structure. Excellent powder diffraction data were collected at the POLARIS Beamline of ISIS, Rutherford Appleton Lab, and were subjected to Rietveld analysis. Neutron derived information sheds light on the unusual effects found for Al3+ substitution on the compressibility of the silicate perovskite [1]. 1. J. Zhang and D. J. Weidner, Science 284, 782 (1999). 2. J. P. Brodholt, Nature 407, 620 (2000). 3. A. Navrotsky, Science 284, 1788 (1999). 4. N. L. Ross and R. M. Hazen, Phys. Chem. Minerals 17, 228 (1990).

  2. Structure and properties of ITQ-8: a hydrous layer silicate with microporous silicate layers.

    PubMed

    Marler, Bernd; Müller, Melanie; Gies, Hermann

    2016-06-21

    ITQ-8 is a new hydrous layer silicate (HLS) with a chemical composition of [C4H8(C7H13N)2]8 [Si64O128(OH)16]·48H2O per unit cell. The synthesis of ITQ-8 was first described in 2002 by Díaz-Cabañas et al., the structure of this material, however, remained unsolved at that time. Physico-chemical characterization using solid-state NMR spectroscopy, SEM, TG-DTA, and FTIR spectroscopy confirmed that ITQ-8 is a layer silicate. The XRD powder pattern was indexed in the monoclinic system with lattice parameters of a0 = 35.5168(5) Å, b0 = 13.3989(2) Å, c0 = 16.0351(2) Å, β = 106.74(2)°. The crystal structure was solved by simulated annealing. Rietveld refinement of the structure in space group C2/c converged to residual values of RBragg = 0.023, RF = 0.022 and chi(2) = 2.3 confirming the structure model. The structure of ITQ-8 contains silicate layers with a topology that resembles a (11-1) section of the framework of zeolite levyne. So far, this layer topology is unique among layer silicates. The layer can be regarded as made up of 4-, 6-, double-six and 8-rings which are interconnected to form cup-like "half-cages". Unlike other HLSs, which possess impermeable silicate layers, ITQ-8 contains 8-rings pores with a free diameter of 3.5 Å × 3.4 Å and can be regarded as a "small-pore layer silicate". In the crystal structure, the organic cations, 1,4-diquiniclidiniumbutane, used as structure directing agents during synthesis are intercalated between the silicate layers. Clusters (bands) of water molecules which are hydrogen bonded to each other and to the terminal Si-OH/Si-O(-) groups are located between the organic cations and interconnect the silicate layers. ITQ-8 is a very interesting material as precursor for the synthesis of microporous framework silicates by topotactic condensation or interlayer expansion reactions leading to 3D micro-pore systems which may be useful in applications as e.g. catalysts, catalyst supports and adsorbents of for separation.

  3. Water and the density of silicate glasses

    NASA Astrophysics Data System (ADS)

    Richet, Pascal; Whittington, Alan; Holtz, François; Behrens, Harald; Ohlhorst, Susanne; Wilke, Max

    A review of published and newly measured densities for 40 hydrous silicate glasses indicates that the room-temperature partial molar volume of water is 12.0+/-0.5cm3/mol. This value holds for simple or mineral compositions as well as for complex natural glasses, from rhyolite to tephrite compositions, prepared up to 10-20kbar pressures and containing up to 7wt% H2O. This volume does not vary either with the molar volume of the water-free silicate phase, with its degree of polymerization or with water speciation. Over a wide range of compositions, this constant value implies that the volume change for the reaction between hydroxyl ions and molecular water is zero and that, at least in glasses, speciation does not depend on pressure. Consistent with data from Ochs and Lange (1997, 1999), systematics in volume expansion for SiO2-M2O systems (M=H, Li, Na, K) suggests that the partial molar thermal expansion coefficient of H2O is about 4× 10-5 K-1 in silicate glasses.

  4. Premixed calcium silicate cement for endodontic applications

    PubMed Central

    Persson, Cecilia; Engqvist, Håkan

    2011-01-01

    Calcium silicate-based materials (also called MTA) are increasingly being used in endodontic applications. However, the handling properties of MTA are not optimal when it comes to injectability and cohesion. Premixing the cements using glycerol avoids these issues. However, there is a lack of data on the effect of common cement variables on important properties of premixed cements for endodontic applications. In this study, the effects of liquid-to-powder ratio, amount of radiopacifier and amount of calcium sulfate (added to control the setting time) were screened using a statistical model. In the second part of the study, the liquid-to-powder ratio was optimized for cements containing three different amounts of radiopacifier. Finally, the effect of using glycerol rather than water was evaluated in terms of radiopacity. The setting time was found to increase with the amount of radiopacifier when the liquid-to-powder ratio was fixed. This was likely due to the higher density of the radiopacifier in comparison to the calcium silicate, which gave a higher liquid-to-powder ratio in terms of volume. Using glycerol rather than water to mix the cements led to a decrease in radiopacity of the cement. In conclusion, we were able to produce premixed calcium silicate cements with acceptable properties for use in endodontic applications. PMID:23507729

  5. Adsorption of dimeric surfactants in lamellar silicates

    NASA Astrophysics Data System (ADS)

    Balcerzak, Mateusz; Pietralik, Zuzanna; Domka, Ludwik; Skrzypczak, Andrzej; Kozak, Maciej

    2015-12-01

    The adsorption of different types of cationic surfactants in lamellar silicates changes their surface character from hydrophilic to hydrophobic. This study was undertaken to obtain lamellar silicates modified by a series of novel dimeric (gemini) surfactants of different length alkyl chains and to characterise these organophilised materials. Synthetic sodium montmorillonite SOMASIF® ME 100 (M) and enriched bentonite of natural origin (Nanoclay - hydrophilic bentonite®) were organophilised with dimeric (gemini) surfactants (1,1‧-(1,4-butanediyl)bis(alkoxymethyl)imidazolium dichlorides). As a result of surfactant molecule adsorption in interlamellar space, the d-spacing (d001) increased from 0.97 nm (for the anhydrous structure) to 2.04 nm. A Fourier transform infrared spectroscopy (FTIR) analysis of the modified systems reveals bands assigned to the stretching vibrations of the CH2 and CH3 groups and the scissoring vibrations of the NH group from the structure of the dimeric surfactants. Thermogravimetric (TG) and derivative thermogravimetric (DTG) studies imply a four-stage process of surfactant decomposition. Scanning electron microscopy (SEM) images provide information on the influence of dimeric surfactant intercalation into the silicate structures. Particles of the modified systems show a tendency toward the formation of irregularly shaped agglomerates.

  6. Lead-silicate glass optical microbubble resonator

    SciTech Connect

    Wang, Pengfei; Ward, Jonathan; Yang, Yong; Chormaic, Síle Nic; Feng, Xian; Brambilla, Gilberto; Farrell, Gerald

    2015-02-09

    Microbubble whispering gallery resonators have the potential to become key components in a variety of active and passive photonic circuit devices by offering a range of significant functionalities. Here, we report on the fabrication, optical characterization, and theoretical analysis of lead-silicate glass and optical microbubble resonators. Evanescent field coupling to the microbubbles was achieved using a 1 μm diameter, silica microfiber at a wavelength of circa 775 nm. High Q-factor modes were efficiently excited in both single-stem and two-stem, lead-silicate glass, and microbubble resonators, with bubble diameters of 38 μm (single-stem) and 48 μm (two-stem). Whispering gallery mode resonances with Q-factors as high as 2.3 × 10{sup 5} (single-stem) and 7 × 10{sup 6} (two-stem) were observed. By exploiting the high-nonlinearity of the lead-silicate glass, this work will act as a catalyst for studying a range of nonlinear optical effects in microbubbles, such as Raman scattering and four-wave mixing, at low optical powers.

  7. Low-loss channel optical waveguide fabrication in Nd(3+)-doped silicate glasses by femtosecond laser direct writing.

    PubMed

    Li, Shi-Ling; Han, Peigao; Shi, Meng; Yao, Yicun; Hu, Bing; Wang, Mingwei; Zhu, Xiaonong

    2011-11-21

    Optical waveguides were fabricated in neodymium-doped silicate glass by using a low-repetition-rate (1 kHz) femtosecond laser inscription. Two different types of waveguide structure are fabricated. In the first, guiding occurs in the focal spot. In the second, guiding occurs in the region between the two filaments. The near-field intensity distribution, propagation loss, index profile reconstruction, and calculation of the modal intensity distribution by the beam propagation method of these waveguides are presented. On the basis of near-field intensity distribution of the light guided through the waveguides and the propagation loss measurement, the optimum writing conditions such as the pulse energy and scan velocity were determined. The waveguide written with 2.2 µJ pulse energy and 50 µm/s scan velocity shows strong guidance at 632.8 nm, with an index contrast of 7 × 10(-4) and a propagation loss of ~0.8 dB/cm.

  8. Homogeneous liquid-liquid extraction of neodymium(III) by choline hexafluoroacetylacetonate in the ionic liquid choline bis(trifluoromethylsulfonyl)imide.

    PubMed

    Onghena, Bieke; Jacobs, Jeroen; Van Meervelt, Luc; Binnemans, Koen

    2014-08-14

    The ionic liquid choline bis(trifluoromethylsulfonyl)imide, [Chol][Tf2N], was used for the extraction of neodymium(III), in combination with choline hexafluoroacetylacetonate, [Chol][hfac], as the extractant. The binary mixture of [Chol][Tf2N] and water shows temperature-dependent phase behavior, with an upper critical solution temperature of 72 °C. A novel extraction technique, homogeneous liquid-liquid extraction (HLLE), was applied to this solvent system. HLLE is based on the use of thermomorphic solvent mixtures and has the advantage of forming a homogeneous phase during mixing. Extraction is not kinetically hindered by an interface and the extraction equilibrium is reached faster than in the case of heterogeneous mixing in conventional solvent extraction. Several extraction parameters were studied for the extraction of neodymium(III) with [Chol][hfac]: temperature, pH, extractant concentration and loading of the ionic liquid phase. A speciation study was performed to determine the stoichiometry of the extracted neodymium(III) complex and a plausible extraction mechanism is proposed. Neodymium is extracted as a tetrakis hexafluoroacetylacetonate complex with one choline cation as counter ion. The crystal structure of the extracted complex showed the presence of a coordination bond between the choline counter ion and the neodymium(III) center, resulting in a coordination number of nine. The stripping of the loaded neodymium and the influence of acid and extractant concentrations on the phase behavior of the [Chol][Tf2N]-H2O system were investigated.

  9. Phosphorus partitioning among mantle silicate phases

    NASA Astrophysics Data System (ADS)

    Xirouchakis, D.; Draper, D. S.

    2002-05-01

    In the absence of a phosphate phase, phosphorus may be considered to behave as an incompatible element during partial melting of mantle mineral assemblages and/or crystallization of residual basaltic liquids. Thus, phosphorus can give valuable constraints on the extent of partial melting and/or magma crystallization, providing that crystal-liquid partition coefficients for P2O5 are known with confidence. In phosphate-normative rocks most of P2O5 is likely contained in phosphate minerals, however, in rocks containing only trace amounts of this oxide, as is often the case of mantle peridotites, silicate minerals can apparently host a large proportion of the bulk P2O5 content. Considering the small differences in the ionic radii of tetrahedrally coordinated P5+ (0.31 Å), Si4+ (0.26 Å), and Al3+ (0.39 Å) the potential for phosphorus incorporation into crystalline silicates is perhaps unsurprising. Although silicate and phosphate phases can be isostructural (e.g., (Fe, Mg)2SiO4 vs. LiMgPO4 or SiO2 vs. AlPO4), this does not warranty mutual solubility (Bradley et al 1966; Brunet et al. 2000). Neglecting the rare reports of significant (2-4 wt%) but also poorly understood P2O5 enrichment in olivine and pyroxene grains in a few extraterrestrial and terrestrial samples (Buseck and Clark, 1984; Goodrich 1984), the overlap in the P2O5 content (wt%) in olivine, pyroxene(s), garnet, and plagioclase, regardless of differences in analytical techniques and compositions, suggests that incorporation of trace quantities of phosphorus in these minerals appears plausible. Parenthetically, there is also considerable overlap in the few published (Henderson 1968; Anderson & Greenland 1969; Thompson 1975; Libourel et al. 1994) or unpublished (Xirouchakis and Draper unpubl. data) partition coefficients for these minerals and mafic silicate liquids. The mechanisms that allow phosphorus to enter the silicate minerals of interest remain unclear or poorly understood, and certainly need to be

  10. Silicate release from glass for pharmaceutical preparations.

    PubMed

    Bohrer, Denise; Bortoluzzi, Fabiana; Nascimento, Paulo Cícero; Carvalho, Leandro Machado; Ramirez, Adrian Gustavo

    2008-05-01

    Glass is made of polymeric silica and other minor components, which are necessary for turning the silica into a material more easily moldable and resistant to temperature changes. Glass containers for pharmaceutical usage are classified according to their resistance to a chemical attack, a test carried out in the presence of water and heat. The test is designed to show the released alkalinity, a variable dependent on the amount of sodium oxide, one of the minor components added to the glass mass. In this work, the release of silica from glass by action of constituents from pharmaceutical formulations was investigated. The study included products used in large volumes and usually stored in glass containers. Solutions of amino acids, electrolytes, glucose, oligoelements and others such as heparin and sodium bicarbonate were individually stored in glass containers and heated at 121 degrees C for 30min, as in the water attack test. The test was also carried out only with water, where the pH varied from 2 to 12. The released silicate was measured either by photometry or atomic absorption spectrometry, depending on the nature of the sample. The results showed that silicate is released during the heating cycle even if the contact is with pure water only. The pH exerts a considerable influence on the release, being that the higher the pH, the higher the silica dissolved. An elevated pH, however, is not the only factor responsible for silica dissolution. While in the solutions of NaCl, KCl, Mg Cl2 and ZnSO4 and in most of the amino acids, the concentration of silicate was as high as in pure water (0.1-1.0mg Si/L). In the solutions of sodium acetate, bicarbonate and gluconate, its concentration was much higher, over 30mg Si/L. These results were confirmed by the analysis of commercial products, where in solutions of amino acids the level of silicate ranged from 0.14 to 0.19mg Si/L. On the other hand, calcium gluconate, sodium bicarbonate and potassium phosphate presented

  11. Diseases associated with exposure to silica and nonfibrous silicate minerals. Silicosis and Silicate Disease Committee

    SciTech Connect

    Not Available

    1988-07-01

    Silicosis, a disease of historical importance, continues to occur cryptically today. Its pathogenesis is under ongoing study as new concepts of pathobiology evolve. In this article, the gross and microscopic features of the disease in the lungs and the lesions in lymph nodes and other viscera are described. These tissue changes are then discussed in the context of clinical disease and other possible or established complications of silica exposure (ie, scleroderma and rheumatoid arthritis, glomerulonephritis, and bronchogenic carcinoma). Silicates are members of a large family of common minerals, some of which have commercial importance. Silicates are less fibrogenic than silica when inhaled into the lungs, but cause characteristic lesions after heavy prolonged exposure. The features of these disease conditions are described herein. Various aspects of the mineralogy and tissue diagnosis of silicosis and lung disease due to silicates are reviewed. An overview of contemporary regulatory considerations is provided.204 references.

  12. An Evaluation of Ethyl Silicate-Based Grouts for Weathered Silicate Stones

    NASA Astrophysics Data System (ADS)

    Dolph, Brittany Helen

    Culturally significant monuments made of weathered siliceous stone often display sub-surface condition issues such as cracks and voids. These issues require grouts that are ideally compatible with the composition and properties of the substrate. Based on the successful application of ethyl silicates as consolidants in recent literature, this study examines possible formulation pathways for the development of a grout incorporating ethyl silicate. Tetraethylorthosilicate (TEOS), dibutyltin dilaurate (DBTL) as a catalyst, silicone oil (PDMS), various grades of ground quartz, sepiolite, and hollow glass spheres were used in differing concentrations to create samples. These were visually and physically assessed on workability, separation, shrinkage, cracking, strength, and flexibility. Quantitative analysis was performed on selected formulations using UV-Vis-NIR reflectance spectroscopy in coordination with a weight loss experiment to investigate kinetics, dynamic mechanical analysis (DMA), and scanning electron microscopy (SEM). Successful formulations tended to include oligomeric TEOS, crushed quartz of mixed grades, sepiolite powder, and PDMS, and show promise for future investigations.

  13. Bioaccumulation of cerium and neodymium by Bacillus cereus isolated from rare earth environments of Chavara and Manavalakurichi, India.

    PubMed

    Challaraj Emmanuel, E S; Vignesh, V; Anandkumar, B; Maruthamuthu, S

    2011-10-01

    Rare earth elements (REEs) are among the common minerals in the Rare earth environment that are very precious and also enhance soil properties. The aim of this present study is to evaluate the accumulation of REEs by bacterial isolates of rare earth environment. Morphological and biochemical characterization were done for 37 bacterial isolates and also molecular studies were carried out using 16S rRNA sequencing method. The assessment of REEs composition in soil samples of Chavara and Manavalakurichi analyzed using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) showed the abundance of Cerium and Neodymium among lanthanides. The bioaccumulation study of rare earth elements by Bacillus cereus were accomplished employing FT-IR spectrum and ICP-OES analysis. The significant accumulation of rare earth elements especially Cerium and Neodymium was noticed in Bacillus cereus isolated from rare earth environment.

  14. ELEMENTS OF LASER SETUPS: Highly efficient passive Q switches for a neodymium laser based on thiopyrylotricarbocyanine dyes

    NASA Astrophysics Data System (ADS)

    Bezrodnyi, V. I.; Derevyanko, Nadezhda A.; Ishchenko, Aleksandr A.; Kropachev, A. V.

    2009-01-01

    The spectral, photochemical and nonlinear optical properties of a group of thiopyrylotricarbocyanine dyes in a polyurethane matrix are studied and compared with well-known materials for passive Q-switching such as nickel BDN and BDNII complexes. Passive laser Q switches based on these dyes feature the high modulation efficiency (up to 76%) in neodymium lasers and high photochemical stability. It is shown that the service life of Q switches can be considerably increased by removing oxygen from a polymer matrix.

  15. Neodymium glass laser with a pulse energy of 220 J and a pulse repetition rate of 0.02 Hz

    SciTech Connect

    Kuzmin, A A; Kulagin, O V; Khazanov, Efim A; Shaykin, A A

    2013-07-31

    A compact neodymium glass laser with a pulse energy of 220 J and a record-high pulse repetition rate of 0.02 Hz (pulse duration 30 ns) is developed. Thermally induced phase distortions are compensated using wave phase conjugation. The integral depolarisation of radiation is decreased to 0.4% by using linear compensation schemes. The second harmonic of laser radiation can be used for pumping Ti : sapphire multipetawatt complexes. (letters)

  16. Supported neodymium catalysts for isoprene and rac-β-butyrolactone polymerization: modulation of reactivity by controlled grafting.

    PubMed

    Terrier, Michael; Brulé, Emilie; Vitorino, Marta J; Ajellal, Noureddine; Robert, Carine; Gauvin, Régis M; Thomas, Christophe M

    2011-01-17

    A series of hybrid materials, bearing neodymium silylamide initiating groups, have been shown to mediate isoprene polymerization when combined with alkyl aluminum activators [methylaluminoxane, AlEt(2)Cl, Al(iBu)(3)]. The surface species nature and relative distribution were correlated with isoprene polymerization activity and selectivity. This approach to stereocontrol modulation has been extended to racemic β-butyrolactone isoselective ring opening polymerization.

  17. Vitreous changes after neodymium-YAG laser irradiation of the posterior lens capsule or mid-vitreous

    SciTech Connect

    Lerman, S.; Thrasher, B.; Moran, M.

    1984-04-01

    Exposure of four monkey and 26 rabbit eyes to neodymium-YAG laser irradiation to the posterior lens capsule or the mid-vitreous area clearly demonstrated significant vitreous changes (liquefaction) as measured by viscosity analyses and proton relaxation studies. We found marked molecular alterations in the vitreous of the exposed eye compared with the contralateral control (unirradiated) eye. These alterations, occurring immediately after laser treatment, were probably the result of acoustic transients accompanying the laser irradiation.

  18. Variations in the neodymium and strontium isotopic composition and REE content of molluscan shells from the Cretaceous Western Interior seaway

    SciTech Connect

    Whittaker, S.G.; Kyser, T.K. )

    1993-08-01

    Rare earth element concentrations, [epsilon][sub ND](T) values, and strontium isotopic compositions of mollusc shells were used to trace variations in the neodymium and strontium isotopic composition of the epicontinental Late Cretaceous Western Interior seaway of North America. Rare earth element patterns are different in aragonite and calcite produced by the molluscs endemic to the seaway, indicating that either mineralogical control or possibly scavenging by organic films associated with the different phases of biogenic carbonate resulted in differential partitioning of the REEs from seawater during shell formation. The biogenic carbonate also may contain REEs associated with Fe-flocs trapped in the shells during growth, but these flocs cannot result in different REE patterns of aragonite and calcite produced by the molluscs. The neodymium isotopic composition of the Western Interior seaway is inferred to have varied 13 [epsilon]-units over 20 My as a result of incursions of seawater from the Arctic Ocean and Gulf of Mexico, river influx from tectonically active terranes, benthic diagenetic fluxes, and volcanic ash falls. Ash from a variety of volcanic centers in western North America was significant in producing rapid and marked changes in [sup 143]Nd/[sup 144]Nd ratios of the seaway, and abrupt regional variations in neodymium isotopic composition of the seaway make the construction of an accurate neodymium isotope evolution curve difficult for this basin. Strontium isotopic compositions of the mollusc shells indicate the [sup 87]Sr/[sup 86]Sr ratio of the Western Interior seaway was generally similar to contemporaneous oceans, although, periodically, the basin had strontium isotopic compositions distinct from contemporaneous seawater. 58 refs., 7 figs., 3 tabs.

  19. Mode locking and Q switching of a diode laser pumped neodymium-doped yttrium lithium fluoride laser

    SciTech Connect

    Maker, G.T.; Ferguson, A.I.

    1989-01-30

    We have developed a mode-locked, diode pumped, neodymium-doped yttrium lithium fluoride (Nd:YLF) laser operating at 1.053 ..mu..m. The laser produces pulses of 18 ps duration at an average power level of 12 mW. When Q switched the duration of the pulse train was 140 ns, giving rise to peak powers of 15 kW.

  20. Adsorption of β-carotene on modified magnesium silicate

    NASA Astrophysics Data System (ADS)

    Sun, Shanshan; Guo, Ning; Fu, Yongfeng

    2016-02-01

    Modified flocculation magnesium silicate is prepared by a hydrothermal process at 120°C for 18 h after adding Al2(SO4)3 into the magnesium silicate gel. Compared with standard magnesium silicate with 328.116 m2 g-1 surface area, this modified magnesium silicate has a bigger BET surface area of 536.803 m2 g-1 and a lower interlayer water content. Modified magnesium silicate exhibits high β-carotene adsorption with a maximum adsorption capacity of 364.96 mg g-1. It is shown that when suspended in organic solvent, this material can be used effectively for carotenoid separation. Furthermore, our results suggest that modified magnesium silicate may be a promising candidate as an absorbent in the decoloring of oil.

  1. 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.

  2. Modeling Nanomechanical Behavior of Calcium-Silicate-Hydrate

    DTIC Science & Technology

    2012-08-01

    ER D C/ G SL T R -1 2 -3 0 Multiscale Modeling of the Structure of Material Modeling Nanomechanical Behavior of Calcium - Silicate -Hydrate...Nanomechanical Behavior of Calcium - Silicate -Hydrate Mei Qiang Chandler and John F. Peters Geotechnical and Structures Laboratory U.S. Army Engineer...DEM) was used to model the nanomechanical behavior of Calcium - Silicate -Hydrate (C-S-H). The inter- particle forces consist of the traditional friction

  3. Experiments of water formation on warm silicates

    SciTech Connect

    He, Jiao; Vidali, Gianfranco

    2014-06-10

    When dust grains have a higher temperature than they would have in dense clouds, and when H, H{sub 2}, and O{sub 2} have a negligible residence time on grains, the formation of water should still be possible via the hydrogenation of OH and Eley-Rideal-type reactions. We determined that the OH desorption energy from an amorphous silicate surface is at least 143 meV (1656 K). This is 400 K higher than the value previously used in chemical models of the interstellar medium and is possibly as high as 410 meV (4760 K). This extends the temperature range for the efficient formation of water on grains from about 30 K to at least 50 K, and possibly over 100 K. We do not find evidence that water molecules leave the surface upon formation. Instead, through a thermal programmed desorption experiment, we find that water formed on the surface of an amorphous silicate desorbs at around 160 K. We also measured the cross-sections for the reaction of H and D with an O{sub 3} layer on an amorphous silicate surface at 50 K. The values of the cross-sections, σ{sub H} = 1.6 ± 0.27 Å{sup 2} and σ{sub D} = 0.94 ± 0.09 Å{sup 2}, respectively, are smaller than the size of an O{sub 3} molecule, suggesting the reaction mechanism is more likely Eley-Rideal than hot-atom. Information obtained through these experiments should help theorists evaluate the relative contribution of water formation on warm grains versus in the gas phase.

  4. Dentinal Tubule Penetration of Tricalcium Silicate Sealers.

    PubMed

    McMichael, Greer E; Primus, Carolyn M; Opperman, Lynne A

    2016-04-01

    The treatments for which mineral trioxide aggregate (MTA)-based materials can be used in dentistry are expanding. Smaller particle size and easier handling properties have allowed the advent of tricalcium silicate sealers including EndoSequence BC Sealer (Brasseler USA, Savannah, GA), QuickSet2 (Avalon Biomed, Bradenton, FL), NeoMTA Plus (Avalon Biomed), and MTA Fillapex (Angelus, Londrina, Brazil). The objective of this study was to measure the tubule penetration with these sealers using continuous wave (CW) and single-cone (SC) obturation techniques. Eighty single-rooted teeth were randomly divided into 8 groups of 10 and obturated with 1 of the previously mentioned sealers mixed with trace amounts of rhodamine using either the CW or SC technique. Teeth were sectioned at 1 mm and 5 mm from the apex and examined under a confocal laser microscope. The percentage of sealer penetration and the maximum sealer penetration were measured. The tricalcium silicate sealers penetrated tubules as deep as 2000 μm (2 mm). The percentage of sealer penetration was much higher 5 mm from the apex, with many specimens having 100% penetration for both SC and warm vertical techniques. MTA Fillapex, a resin-based sealer with less than 20% MTA particles, had significantly greater tubule penetration with a warm vertical technique versus the SC technique at the 1-mm level. Within the limitations of this study, the CW and SC techniques produced similar tubule penetration at both the 1-mm and the 5-mm level with the tricalcium silicate sealers BC Sealer, QuickSet2, and NeoMTA Plus. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

  5. Determination of chlorine in silicate rocks

    USGS Publications Warehouse

    Peck, L.C.

    1959-01-01

    In a rapid accurate method for the determination of chlorine in silicate rocks, the rock powder is sintered with a sodium carbonate flux containing zinc oxide and magnesium carbonate. The sinter cake is leached with water, the resulting solution is filtered, and the filtrate is acidified with nitric acid. Chlorine is determined by titrating this solution with mercuric nitrate solution using sodium nitroprusside as the indicator. The titration is made in the dark with a beam of light shining through the solution. The end point of the titration is found by visually comparing the intensity of this beam of light with that of a similar beam of light in a reference solution.

  6. Preparation of reactive beta-dicalcium silicate

    DOEpatents

    Shen, M.S.; Chen, J.M.; Yang, R.T.

    1980-02-28

    This invention relates to the preparation of fine particles of reactive beta-dicalcium silicate by means of a solid state process which comprises firing a mixture of calcium sulfate, silica, and a reducing additive selected from the group consisting of calcium sulfide, carbon, carbon monoxide, methane, and hydrogen, at a temperature of about 850 to 1000/sup 0/C. A carrier gas such as nitrogen or carbon dioxide may also be added, if desired. A high concentration of sulfur dioxide is a by-product of this process.

  7. Lithium metaborate flux in silicate analysis

    USGS Publications Warehouse

    Ingamells, C.O.

    1970-01-01

    Lithium metaborate is an effective flux for silicates and other rock-forming minerals. The glass resulting from fusion is mechanically strong, reasonably nonhygroscopic, and is readily soluble in dilute acids. These characteristics lead to its use in X-ray spectrography and in methods which require whole-rock solutions, such as atomic absorption and emission spectrometry. Difficulties have been encountered in the use of such techniques : a high-quality reagent has been difficult to obtain ; fusion conditions must be rather closely controlled; graphite crucibles used in the fusions need special treatment. Methods for overcoming these difficulties are outlined. Selected procedures for various instrumental methods of analysis are described. ?? 1970.

  8. Activity composition relationships in silicate melts

    SciTech Connect

    Glazner, A.F.

    1990-01-01

    Equipment progress include furnace construction and electron microprobe installation. The following studies are underway: phase equilibria along basalt-rhyolite mixing line (olivine crystallization from natural silicic andensites, distribution of Fe and Mg between olivine and liquid, dist. of Ca and Na between plagioclase and liquid), enthalpy-composition relations in magmas (bulk heat capacity of alkali basalt), density model for magma ascent and contamination, thermobarometry in igneous systems (olivine/plagioclase phenocryst growth in Quat. basalt), high-pressure phase equilibria of alkali basalt, basalt-quartz mixing experiments, phase equilibria of East African basalts, and granitic minerals in mafic magma. (DLC)

  9. Preparation of reactive beta-dicalcium silicate

    DOEpatents

    Shen, Ming-Shing; Chen, James M.; Yang, Ralph T.

    1982-01-01

    This invention relates to the preparation of fine particles of reactive beta-dicalcium silicate by means of a solid state process which comprises firing a mixture of calcium sulfate, silica and a reducing additive selected from the group consisting of calcium sulfide, carbon, carbon monoxide, methane and hydrogen, at a temperature of about 850.degree.-1000.degree. C. A carrier gas such as nitrogen or carbon dioxide may also be added, if desired. A high concentration of sulfur dioxide is a by-product of this process.

  10. Microbial dissolution of silicate materials. Final report

    SciTech Connect

    Schwartzman, D.

    1996-03-26

    The objective of this research was to better understand the role of selected thermophilic bacteria in the colonization and dissolution of silicate minerals, with potential applications to the HDR Project. The demonstration of enhanced dissolution from microbial effects is critically dependent on providing a mineral bait within a media deficient in the critical nutrient found in the mineral (e.g., Fe). Reproducible experimental conditions in batch experiments require agitation to expose mineral powders, as well as nearly similar initial conditions for both inoculated cultures and controls. It is difficult, but not impossible to ensure reproducible conditions with microbes favoring filamentous growth habits.

  11. Evaluating United States and world consumption of neodymium, dysprosium, terbium, and praseodymium in final products

    NASA Astrophysics Data System (ADS)

    Hart, Matthew

    This paper develops scenarios of future rare-earth-magnet metal (neodymium, dysprosium, terbium, and praseodymium) consumption in the permanent magnets used in wind turbines and hybrid electric vehicles. The scenarios start with naive base-case scenarios for growth in wind-turbine and hybrid-electric-vehicle sales over the period 2011 to 2020, using historical data for each good. These naive scenarios assume that future growth follows time trends in historical data and does not depend on any exogenous variable. Specifically, growth of each technological market follows historical time trends, and the amount of rare earths used per unit of technology remains fixed. The chosen reference year is 2010. Implied consumptions of the rare earth magnet metals are calculated from these scenarios. Assumptions are made for the material composition of permanent magnets, the market share of permanent-magnet wind turbines and vehicles, and magnet weight per unit of technology. Different scenarios estimate how changes in factors like the material composition of magnets, growth of the economy, and the price of a substitute could affect future consumption. Each scenario presents a different method for reducing rare earth consumption and could be interpreted as potential policy choices. In 2010, the consumption (metric tons, rare-earth-oxide equivalent) of each rare-earth-magnet metal was as follows. Total neodymium consumption in the world for both technologies was 995 tons; dysprosium consumption was 133 tons; terbium consumption was 50 tons; praseodymium consumption was zero tons. The base scenario for wind turbines shows there could be strong, exponential growth in the global wind turbine market. New U.S. sales of hybrid vehicles would decline (in line with the current economic recession) while non-U.S. sales increase through 2020. There would be an overall increase in the total amount of magnetic rare earths consumed in the world. Total consumption of each rare earth in the short

  12. Neodymium Isotope data for Foraminifera Indicates Increased Nile Outflow During Mediterranean Anoxic Events

    NASA Astrophysics Data System (ADS)

    Scrivner, A. E.; Vance, D.; Rohling, E. J.

    2001-12-01

    The environmental conditions leading to deep water anoxia in the Eastern Mediterranean during sapropel formation remain controversial. It is broadly accepted that sapropels are the result of either water column stagnation or increased export production, or both. Oxygen isotopes indicate reduced surface-water salinities during sapropel formation, which would have facilitated deep-water stagnation via convective stabilisation of the water column. A number of sources for the additional freshwater have been proposed, including glacial meltwater influx, increased outflow from European rivers, increased precipitation over the Mediterranean region as a whole, and increased Nile outflow due to intensification of the African monsoon. Oxygen isotopes by themselves cannot fully distinguish between these various possibilities. Though the exact mode of incorporation of neodymium (Nd) into foraminiferal tests remains a matter of debate, Nd isotopes in sedimentary planktonic foraminifera clearly record those in surface seawater and not any other part of the water column or the sediment1,2. Here we present Nd isotopic data for both the present-day Nile and for sedimentary foraminifera from ODP core 967, which demonstrate a significant increase in Nile outflow during the formation of sapropel S5. Samples of Nile river water were collected from the Sudan in the dry season and analysed for neodymium isotope compositions. These analyses clearly show that the River Nile has both a very high neodymium concentration compared to the Mediterranean and a distinct 143Nd/144Nd ratio. \\epsilonNd (defined as ((143Nd/144Ndsample)/(143Nd/ 144NdCHUR)-1)\\times104) for the main Nile around and below Khartoum is -3. In the wet season (sampling in progress), the Blue Nile (\\epsilonNd = +1) dominates over the White Nile (\\epsilonNd = -16) and the total Nile discharge is vastly greater, so that the annually-integrated \\epsilonNd of the main Nile should be even higher than -3. In contrast, the

  13. Group II tris(glycolato)silicates as precursors to silicate glasses and ceramics

    SciTech Connect

    Kansal, P.; Laine, R.M.

    1995-03-01

    Group II tris(glycolato)silicates, MSi(OCH{sub 2}CH{sub 2}O){sub 3} (where M = Ba, Ca, Mg), can be synthesized directly by reaction of silica with ethylene glycol and alkaline-earth (group II) oxides at 200 C. These hexa-alkoxy silicates serve as precursors to silicate glass and ceramic powders. They are readily modified by exchange with longer-chain diols into proper precursors. These rheologically useful precursors may provide access to silicate or aluminosilicate powders, thin films, fibers, and coatings. Thus, the authors have examined the utility of hexacoordinate glycolatosilicates as model precursors. Pyrolysis of the compounds, MSi(OCH{sub 2}CH{sub 2})O{sub 3}, in air transforms them to their anticipated ceramic products, MO{center_dot}SiO{sub 2}. The phase transformation and chemical changes that occur during pyrolysis were characterized using X-ray powder diffractometry (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), thermal gravimetric analysis (TGA), differential thermal analysis (DTA), and scanning electron microscopy (SEM). The hexacoordinate glycolatosilicates oxidatively decompose at {approx}300 C to form amorphous materials. Moderate to significant quantities of the group II carbonates, MCO{sub 3} (15--50 wt%), form coincidentally as the amorphous intermediates trap CO{sub 2} generated by ligand oxidation. At {approx}900 C, the amorphous materials crystallize into the expected, phase-pure, MO{center_dot}SiO{sub 2}.

  14. The interplay between particulate and dissolved neodymium in the Western North Atlantic: First insights and interpretations

    NASA Astrophysics Data System (ADS)

    Stichel, T.; Kretschmer, S.; Lambelet, M.; van de Flierdt, T.; Rutgers van der Loeff, M.; Rijkenberg, M. J. A.; Gerringa, L. J.; De Baar, H. J. W.

    2014-12-01

    Dissolved neodymium (Nd) isotopes (expressed as ɛNd) have been widely used as a water mass tracer to reconstruct paleo ocean circulation. However, the marine geochemical cycle of Nd is not well understood. Unclear input mechanisms, scarcity of available data, and observed decoupling between dissolved ɛNd and Nd concentration patterns ([Nd]) are only a few of the unresolved issues. The latter is often referred to as the Nd paradox(e.g. Goldstein and Hemming 2003). Here we revisit this paradox with an unprecedented data set on particulate Nd isotope and concentration data from five stations along the Dutch GEOTRACES transect GA02 in the western North and equatorial Atlantic Ocean (cruises 64PE319 and 64PE321 from April to July 2010). Particulates were collected with in-situ pumps on 0.8 µm Supor filters and subjected to a total digestion procedure in the home laboratory. The particulates collected farthest north (Irminger Sea and Labrador Sea) show a strong affinity to the nearby land masses in their Nd isotope composition: Very negative values (ɛNd ≈-20) are observed in the Labrador Sea, which is surrounded by old continental rocks. More positive values of up to ɛNd ≈-4 are found east of Greenland probably derived from the Nansen Fjord Formation's basaltic rocks. In these two areas the particulate ɛNd is offset from dissolved Nd isotopes by up to 7.7 ɛ-units, but reveals a similar vertical distribution. Further downstream of the flow path of the North Atlantic Deep Water, dissolved and particulate Nd isotopic compositions in the water column seem to merge and become indistinguishable from one another south of Bermuda (BATS station). This seems to indicate that particulate and dissolved fractions exchange with increasing distance from source regions and age of water masses. Neodymium concentrations in particulates [pNd] are low (KD<5%) and invariant. However, most stations show a significant increase in [pNd] close to the seafloor, where [pNd] nearly

  15. Research drilling in young silicic volcanoes

    SciTech Connect

    Eichelberger, J.C.

    1989-06-30

    Magmatic activity, and particularly silicic magmatic activity, is the fundamental process by which continental crust forms and evolves. The transport of magma from deep crustal reservoirs to the surface is a neglected but important aspect of magmatic phenomena. It encompasses problems of eruptive behavior, hydrothermal circulation, and ore deposition, and must be understood in order to properly interpret deeper processes. Drilling provides a means for determining the relationship of shallow intrusive processes to eruption processes at young volcanoes where eruptions are best understood. Drilling also provides a means for directly observing the processes of heat and mass transfer by which recently emplaced intrusions approach equilibrium with their new environment. Drilling in the Inyo Chain, a 600-year-old chain of volcanic vents in California, has shown the close relationship of silicic eruption to shallow dike emplacement, the control of eruptive style by shallow porous-flow degassing, the origin of obsidian by welding, the development of igneous zonation by viscosity segregation, and the character and size of conduits in relation to well-understood magmatic and phreatic eruptions. 36 refs., 9 figs.

  16. Thermochemistry of dense hydrous magnesium silicates

    NASA Technical Reports Server (NTRS)

    Bose, Kunal; Burnley, Pamela; Navrotsky, Alexandra

    1994-01-01

    Recent experimental investigations under mantle conditions have identified a suite of dense hydrous magnesium silicate (DHMS) phases that could be conduits to transport water to at least the 660 km discontinuity via mature, relatively cold, subducting slabs. Water released from successive dehydration of these phases during subduction could be responsible for deep focus earthquakes, mantle metasomatism and a host of other physico-chemical processes central to our understanding of the earth's deep interior. In order to construct a thermodynamic data base that can delineate and predict the stability ranges for DHMS phases, reliable thermochemical and thermophysical data are required. One of the major obstacles in calorimetric studies of phases synthesized under high pressure conditions has been limitation due to the small (less than 5 mg) sample mass. Our refinement of calorimeter techniques now allow precise determination of enthalpies of solution of less than 5 mg samples of hydrous magnesium silicates. For example, high temperature solution calorimetry of natural talc (Mg(0.99) Fe(0.01)Si4O10(OH)2), periclase (MgO) and quartz (SiO2) yield enthalpies of drop solution at 1044 K to be 592.2 (2.2), 52.01 (0.12) and 45.76 (0.4) kJ/mol respectively. The corresponding enthalpy of formation from oxides at 298 K for talc is minus 5908.2 kJ/mol agreeing within 0.1 percent to literature values.

  17. Tip-induced nanoreactor for silicate

    PubMed Central

    Gao, Ming; Ma, Liran; Liang, Yong; Gao, Yuan; Luo, Jianbin

    2015-01-01

    Nanoscale scientific issues have attracted an increasing amount of research interest due to their specific size-effect and novel structure-property. From macro to nano, materials present some unique chemical reactivity that bulk materials do not own. Here we introduce a facile method to generate silicate with nanoscale control based on the establishment of a confined space between a meso/nanoscale tungsten tip and a smooth silica/silicon substrate. During the process, local water-like droplets deposition can be obviously observed in the confinement between the Si/SiO2 surfaces and the KOH-modified tungsten tip. By the combination of in-situ optical microscopy and Raman spectroscopy, we were able to take a deep insight of both the product composition and the underlying mechanism of such phenomena. It was indicated that such nanoreactor for silicate could be quite efficient as a result of the local capillarity and electric field effect, with implications at both nano and meso scales. PMID:26364882

  18. Thermochemistry of dense hydrous magnesium silicates

    NASA Technical Reports Server (NTRS)

    Bose, Kunal; Burnley, Pamela; Navrotsky, Alexandra

    1994-01-01

    Recent experimental investigations under mantle conditions have identified a suite of dense hydrous magnesium silicate (DHMS) phases that could be conduits to transport water to at least the 660 km discontinuity via mature, relatively cold, subducting slabs. Water released from successive dehydration of these phases during subduction could be responsible for deep focus earthquakes, mantle metasomatism and a host of other physico-chemical processes central to our understanding of the earth's deep interior. In order to construct a thermodynamic data base that can delineate and predict the stability ranges for DHMS phases, reliable thermochemical and thermophysical data are required. One of the major obstacles in calorimetric studies of phases synthesized under high pressure conditions has been limitation due to the small (less than 5 mg) sample mass. Our refinement of calorimeter techniques now allow precise determination of enthalpies of solution of less than 5 mg samples of hydrous magnesium silicates. For example, high temperature solution calorimetry of natural talc (Mg(0.99) Fe(0.01)Si4O10(OH)2), periclase (MgO) and quartz (SiO2) yield enthalpies of drop solution at 1044 K to be 592.2 (2.2), 52.01 (0.12) and 45.76 (0.4) kJ/mol respectively. The corresponding enthalpy of formation from oxides at 298 K for talc is minus 5908.2 kJ/mol agreeing within 0.1 percent to literature values.

  19. Evidence for seismogenic fracture of silicic magma.

    PubMed

    Tuffen, Hugh; Smith, Rosanna; Sammonds, Peter R

    2008-05-22

    It has long been assumed that seismogenic faulting is confined to cool, brittle rocks, with a temperature upper limit of approximately 600 degrees C (ref. 1). This thinking underpins our understanding of volcanic earthquakes, which are assumed to occur in cold rocks surrounding moving magma. However, the recent discovery of abundant brittle-ductile fault textures in silicic lavas has led to the counter-intuitive hypothesis that seismic events may be triggered by fracture and faulting within the erupting magma itself. This hypothesis is supported by recent observations of growing lava domes, where microearthquake swarms have coincided with the emplacement of gouge-covered lava spines, leading to models of seismogenic stick-slip along shallow shear zones in the magma. But can fracturing or faulting in high-temperature, eruptible magma really generate measurable seismic events? Here we deform high-temperature silica-rich magmas under simulated volcanic conditions in order to test the hypothesis that high-temperature magma fracture is seismogenic. The acoustic emissions recorded during experiments show that seismogenic rupture may occur in both crystal-rich and crystal-free silicic magmas at eruptive temperatures, extending the range of known conditions for seismogenic faulting.

  20. Silicate mineralogy at the surface of Mercury

    NASA Astrophysics Data System (ADS)

    Namur, Olivier; Charlier, Bernard

    2017-01-01

    NASA's MESSENGER spacecraft has revealed geochemical diversity across Mercury's volcanic crust. Near-infrared to ultraviolet spectra and images have provided evidence for the Fe2+-poor nature of silicate minerals, magnesium sulfide minerals in hollows and a darkening component attributed to graphite, but existing spectral data is insufficient to build a mineralogical map for the planet. Here we investigate the mineralogical variability of silicates in Mercury's crust using crystallization experiments on magmas with compositions and under reducing conditions expected for Mercury. We find a common crystallization sequence consisting of olivine, plagioclase, pyroxenes and tridymite for all magmas tested. Depending on the cooling rate, we suggest that lavas on Mercury are either fully crystallized or made of a glassy matrix with phenocrysts. Combining the experimental results with geochemical mapping, we can identify several mineralogical provinces: the Northern Volcanic Plains and Smooth Plains, dominated by plagioclase, the High-Mg province, strongly dominated by forsterite, and the Intermediate Plains, comprised of forsterite, plagioclase and enstatite. This implies a temporal evolution of the mineralogy from the oldest lavas, dominated by mafic minerals, to the youngest lavas, dominated by plagioclase, consistent with progressive shallowing and decreasing degree of mantle melting over time.

  1. Crystalline-amorphous transition in silicate perovskites

    SciTech Connect

    Hemmati, M.; Chizmeshya, A. |; Wolf, G.H.; Poole, P.H.; Shao, J.; Angell, C.A.

    1995-06-01

    CaSiO{sub 3} and MgSiO{sub 3} perovskites are known to undergo solid-state crystal to amorphous transitions near ambient pressure when decompressed from their high-pressure stability fields. In order to elucidate the mechanistic aspects of this transition we have performed detailed molecular-dynamics simulations and lattice-dynamical calculations on model silicate perovskite systems using empirical rigid-ion pair potentials. In the simulations at low temperatures, the model perovskite systems transform under tension to a low-density glass composed of corner shared chains of tetrahedral silicon. The amorphization is initiated by a thermally activated step involving a soft polar optic mode in the perovskite phase at the Brillouin zone center. Progression of the system along this reaction coordinate triggers, in succession, multiple barrierless modes of instability ultimately producing a catastrophic decohesion of the lattice. An important intermediary along the reaction path is a crystalline phase where silicon is in a five-coordinate site and the alkaline-earth metal atom is in eightfold coordination. At the onset pressure, this transitory phase is itself dynamically unstable to a number of additional vibrational modes, the most relevant being those which result in transformation to a variety of tetrahedral chain silicate motifs. These results support the conjecture that stress-induced amorphization arises from the near simultaneous accessibility of multiple modes of instability in the highly metastable parent crystalline phase.

  2. Carbon Mineralization Using Phosphate and Silicate Ions

    NASA Astrophysics Data System (ADS)

    Gokturk, H.

    2013-12-01

    Carbon dioxide (CO2) reduction from combustion of fossil fuels has become an urgent concern for the society due to marked increase in weather related natural disasters and other negative consequences of global warming. CO2 is a highly stable molecule which does not readily interact with other neutral molecules. However it is more responsive to ions due to charge versus quadrupole interaction [1-2]. Ions can be created by dissolving a salt in water and then aerosolizing the solution. This approach gives CO2 molecules a chance to interact with the hydrated salt ions over the large surface area of the aerosol. Ion containing aerosols exist in nature, an example being sea spray particles generated by breaking waves. Such particles contain singly and doubly charged salt ions including Na+, Cl-, Mg++ and SO4--. Depending on the proximity of CO2 to the ion, interaction energy can be significantly higher than the thermal energy of the aerosol. For example, an interaction energy of 0.6 eV is obtained with the sulfate (SO4--) ion when CO2 is the nearest neighbor [2]. In this research interaction between CO2 and ions which carry higher charges are investigated. The molecules selected for the study are triply charged phosphate (PO4---) ions and quadruply charged silicate (SiO4----) ions. Examples of salts which contain such molecules are potassium phosphate (K3PO4) and sodium orthosilicate (Na4SiO4). The research has been carried out with first principle quantum mechanical calculations using the Density Functional Theory method with B3LYP functional and Pople type basis sets augmented with polarization and diffuse functions. Atomic models consist of the selected ions surrounded by water and CO2 molecules. Similar to the results obtained with singly and doubly charged ions [1-2], phosphate and silicate ions attract CO2 molecules. Energy of interaction between the ion and CO2 is 1.6 eV for the phosphate ion and 3.3 eV for the silicate ion. Hence one can expect that the selected

  3. Neodymium doped fluoroindogallate glasses as highly-sensitive luminescent non-contact thermometers

    NASA Astrophysics Data System (ADS)

    Nunes, Luiz A. O.; Souza, Adelmo S.; Carlos, Luís D.; Malta, Oscar L.

    2017-01-01

    Trivalent neodymium (Nd3+) can be used as high performance temperature luminescent ion sensor, namely in the near infrared spectral region. The disadvantage presented in the use of this ion is that transitions from thermally coupled levels show very different emission intensities. In order to solve this critical problem we propose to use Nd3+-doped fluoroindogallate glasses with low phonon cutoff energy (500 cm-1) as the active medium. By using a dopant concentration that minimizes losses due to cross relaxation processes and detecting the emissions of the thermally coupled levels with a R928 photomultiplier, without correction response for the wavelength dependence of the intensity, we have succeeded in getting the highest relative thermal sensitivities so far observed, 2.5%ṡK-1 and 7.4%ṡK-1, for the 4F5/2 → 4I9/2/4F3/2 → 4I9/2 and 4F7/2 → 4I9/2/4F3/2 → 4I9/2 intensity ratios, respectively at 288 K.

  4. Mineralogy of the mid-ocean-ridge basalt source from neodymium isotopic composition of abyssal peridotites.

    PubMed

    Salters, Vincent J M; Dick, Henry J B

    2002-07-04

    Inferring the melting process at mid-ocean ridges, and the physical conditions under which melting takes place, usually relies on the assumption of compositional similarity between all mid-ocean-ridge basalt sources. Models of mantle melting therefore tend to be restricted to those that consider the presence of only one lithology in the mantle, peridotite. Evidence from xenoliths and peridotite massifs show that after peridotite, pyroxenite and eclogite are the most abundant rock types in the mantle. But at mid-ocean ridges, where most of the melting takes place, and in ophiolites, pyroxenite is rarely found. Here we present neodymium isotopic compositions of abyssal peridotites to investigate whether peridotite can indeed be the sole source for mid-ocean-ridge basalts. By comparing the isotopic compositions of basalts and peridotites at two segments of the southwest Indian ridge, we show that a component other than peridotite is required to explain the low end of the (143)Nd/(144)Nd variations of the basalts. This component is likely to have a lower melting temperature than peridotite, such as pyroxenite or eclogite, which could explain why it is not observed at mid-ocean ridges.

  5. Scalable waveguide design for three-level operation in Neodymium doped fiber laser

    SciTech Connect

    Pax, Paul H.; Khitrov, Victor V.; Drachenberg, Derrek R.; Allen, Graham S.; Ward, Benjamin; Dubinskii, Mark; Messerly, Michael J.; Dawson, Jay W.

    2016-12-12

    We have constructed a double clad neodymium doped fiber laser operating on the three-level 4F3/24I9/2 transition. The laser has produced 11.5 W at 925 nm with 55% slope efficiency when pumped at 808 nm, comparable to the best previous results for a double-clad fiber configuration on this transition. Higher power pumping with both 808 nm and 880 nm sources resulted in an output of 27 W, albeit at lower slope efficiency. In both cases, output power was limited by available pump, indicating the potential for further power scaling. To suppress the stronger four-level 4F3/24I11/2 transition we developed a waveguide that provides spectral filtering distributed along the length of the fiber, based on an all-solid micro-structured optical fiber design, with resonant inclusions creating a leakage path to the cladding. Furthermore, the waveguide supports large mode areas and provides strong suppression at selectable wavelength bands, thus easing the restrictions on core and cladding sizes that limited power scaling of previous approaches.

  6. Scalable waveguide design for three-level operation in Neodymium doped fiber laser

    DOE PAGES

    Pax, Paul H.; Khitrov, Victor V.; Drachenberg, Derrek R.; ...

    2016-12-12

    We have constructed a double clad neodymium doped fiber laser operating on the three-level 4F3/2 → 4I9/2 transition. The laser has produced 11.5 W at 925 nm with 55% slope efficiency when pumped at 808 nm, comparable to the best previous results for a double-clad fiber configuration on this transition. Higher power pumping with both 808 nm and 880 nm sources resulted in an output of 27 W, albeit at lower slope efficiency. In both cases, output power was limited by available pump, indicating the potential for further power scaling. To suppress the stronger four-level 4F3/2 → 4I11/2 transition wemore » developed a waveguide that provides spectral filtering distributed along the length of the fiber, based on an all-solid micro-structured optical fiber design, with resonant inclusions creating a leakage path to the cladding. Furthermore, the waveguide supports large mode areas and provides strong suppression at selectable wavelength bands, thus easing the restrictions on core and cladding sizes that limited power scaling of previous approaches.« less

  7. Rapid neodymium release to marine waters from lithogenic sediments in the Amazon estuary

    PubMed Central

    Rousseau, Tristan C. C.; Sonke, Jeroen E.; Chmeleff, Jérôme; van Beek, Pieter; Souhaut, Marc; Boaventura, Geraldo; Seyler, Patrick; Jeandel, Catherine

    2015-01-01

    Rare earth element (REE) concentrations and neodymium isotopic composition (ɛNd) are tracers for ocean circulation and biogeochemistry. Although models suggest that REE release from lithogenic sediment in river discharge may dominate all other REE inputs to the oceans, the occurrence, mechanisms and magnitude of such a source are still debated. Here we present the first simultaneous observations of dissolved (<0.45 μm), colloidal and particulate REE and ɛNd in the Amazon estuary. A sharp drop in dissolved REE in the low-salinity zone is driven by coagulation of colloidal matter. At mid-salinities, total dissolved REE levels slightly increase, while ɛNd values are shifted from the dissolved Nd river endmember (−8.9) to values typical of river suspended matter (−10.6). Combining a Nd isotope mass balance with apparent radium isotope ages of estuarine waters suggests a rapid (3 weeks) and globally significant Nd release by dissolution of lithogenic suspended sediments. PMID:26158849

  8. Potential interference of small neodymium magnets with cardiac pacemakers and implantable cardioverter-defibrillators.

    PubMed

    Wolber, Thomas; Ryf, Salome; Binggeli, Christian; Holzmeister, Johannes; Brunckhorst, Corinna; Luechinger, Roger; Duru, Firat

    2007-01-01

    Magnetic fields may interfere with the function of cardiac pacemakers and implantable cardioverter-defibrillators (ICDs). Neodymium-iron-boron (NdFeB) magnets, which are small in size but produce strong magnetic fields, have become widely available in recent years. Therefore, NdFeB magnets may be associated with an emerging risk of device interference. We conducted a clinical study to evaluate the potential of small NdFeB magnets to interfere with cardiac pacemakers and ICDs. The effect of four NdFeB magnets (two spherical magnets 8 and 10 mm in diameter, a necklace made of 45 spherical magnets, and a magnetic name tag) was tested in forty-one ambulatory patients with a pacemaker and 29 patients with an ICD. The maximum distance at which the magnetic switch of a device was influenced was observed. Magnetic interference was observed in all patients. The maximum distance resulting in device interference was 3 cm. No significant differences were found with respect to device manufacturer and device types. Small NdFeB magnets may cause interference with cardiac pacemakers and ICDs. Patients should be cautioned about the interference risk associated with NdFeB magnets during daily life.

  9. Neodymium(III) Complexes of Dialkylphosphoric and Dialkylphosphonic Acids Relevant to Liquid-Liquid Extraction Systems

    SciTech Connect

    Lumetta, Gregg J.; Sinkov, Sergey I.; Krause, Jeanette A.; Sweet, Lucas E.

    2016-01-27

    The complexes formed during the extraction of neodymium(III) into hydrophobic solvents containing acidic organophosphorus extractants were probed by single-crystal X-ray diffractometry, visible spectrophotometry, and Fourier-transform infrared spectroscopy. The crystal structure of the compound Nd(DMP)3 (1, DMP = dimethyl phosphate) revealed a polymeric arrangement in which each Nd(III) center is surrounded by six DMP oxygen atoms in a pseudo-octahedral environment. Adjacent Nd(III) ions are bridged by (MeO)2POO– anions, forming the polymeric network. The diffuse reflectance visible spectrum of 1 is nearly identical to that of the solid that is formed when an n-dodecane solution of di-(2-ethylhexyl)phosphoric acid (HA) is saturated with Nd(III), indicating a similar coordination environment around the Nd center in the NdA3 solid. The visible spectrum of the HA solution fully loaded with Nd(III) is very similar to that of the NdA3 material, both displaying hypersensitive bands characteristic of an pseudo-octahedral coordination environment around Nd. These spectral characteristics persisted across a wide range of organic Nd concentrations, suggesting that the pseudo-octahedral coordination environment is maintained from dilute to saturated conditions.

  10. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications

    SciTech Connect

    Zacchia, Nicholas A.; Valentine, Megan T.

    2015-05-15

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  11. Interference of neodymium magnets with cardiac pacemakers and implantable cardioverter-defibrillators: an in vitro study.

    PubMed

    Ryf, Salome; Wolber, Thomas; Duru, Firat; Luechinger, Roger

    2008-01-01

    Permanent magnets may interfere with the function of cardiac pacemakers and implantable cardioverter-defibrillators (ICDs). Neodymium-iron-boron (NdFeB) magnets have become widely available in recent years and are incorporated in various articles of daily life. We conducted an in-vitro study to evaluate the ability of NdFeB magnets for home and office use to cause interference with cardiac pacemakers and ICDs. The magnetic fields of ten NdFeB magnets of different size and shape were measured at increasing distances beginning from the surface until a field-strength (B-field) value of 0.5 mT was reached. Furthermore, for each magnet the distance was determined at which a sample pacemaker switched from magnet mode to normal mode. Depending on the size and remanence of individual magnets, a B-field value of 0.5 mT was found at distances ranging from 1.5 cm to 30 cm and a value of 1 mT at distances from 1 cm to 22 cm. The pacemaker behavior was influenced at distances from 1 cm to 24 cm. NdFeB magnets for home and office use may cause interference with cardiac pacemakers and ICDs at distances up to 24 centimeters. Patient education and product declarations should include information about the risk associated with these magnets.

  12. Osmium and neodymium isotopic constraints on the temporal and spatial evolution of Siberian flood basalt sources

    USGS Publications Warehouse

    Horan, M.F.; Walker, R.J.; Fedorenko, V.A.; Czamanske, G.K.

    1995-01-01

    Picrites from the Gudchikhinsky suite, the oldest rocks examined, have ??Os of +5.3 to +6.1 and ??Nd of +3.7 to +4.0. The osmium and neodymium isotopic compositions of these rocks are similar to some modern ocean-island basalts (OIB), consistent with their derivation from an mantle plume. Picrites from the stratigraphically higher Tuklonsky suite have similar ??Os of +3.4 to +6.5, but ??Nd of -0.9 to -2.6. The similar ??Os, but lower ??Nd , suggest that some magmas from the same OIB-type, mantle source were contaminated by lithospheric components. A differentiated ankaramite flow, associated with the top of the stratigraphically higher Morongovsky suite, has ??Os of +9.8 to +10.2 and ??Nd of +1.3 to +1.4. The higher ??Os may indicate that the plume source was heterogeneous with respect to osmium isotopic composition, consistent with osmium isotopic measurements in rocks from other plume sources. Mg-rich, alkaline rocks (meymechites) from the Guli area that erupted much nearer the end of the flood-basalt event have ??Os of -1.2 to -2.6 and ??Nd of +3.7 to +4.9. These rocks were probably produced by low degrees of partial melting of mantle after the main stages of flood-basalt production. -from Authors

  13. Rhenium-osmium and samarium-neodymium isotopic systematics of the stillwater complex

    USGS Publications Warehouse

    Lambert, D.D.; Morgan, J.W.; Walker, R.J.; Shirey, S.B.; Carlson, R.W.; Zientek, M.L.; Koski, M.S.

    1989-01-01

    Isotopic data for the Stillwater Complex, Montana , which formed about 2700 Ma (million years ago), were obtained to evaluate the role of magma mixing in the formation of strategic platinum-group element (PGE) ore deposits. Neodymium and osmium isotopic data indicate that the intrusion formed from at least two geochemically distinct magmas. Ultramafic affinity (U-type) magmas had initial ??Nd of -0.8 to -3.2 and a chondritic initial 187Os/186Os ratio of ???0.88, whereas anorthositic affinity (A-type) magmas had ??Nd of -0.7 to +1.7 and an initial 187Os/186Os ratio of ???1.13. These data suggest that U-type magmas were derived from a lithospheric mantle source containing recycled crustal materials whereas A-type magmas originated either by crustal contamination of basaltic magmas or by partial melting of basalt in the lower crust. The Nd and Os isotopic data also suggest that Os, and probably the other PGEs in ore horizons such as the J-M Reef, was derived from A-type magmas. The Nd and Os isotopic heterogeneity observed in rocks below the J-M Reef also suggests that A-type magmas were injected into the Stillwater U-type magma chamber at several stages during the development of the Ultramafic series.

  14. Spectroscopic characterization of alkali modified zinc-tellurite glasses doped with neodymium.

    PubMed

    Rajeswari, R; Babu, S Surendra; Jayasankar, C K

    2010-09-15

    Neodymium doped zinc-tellurite glasses of composition TeO(2)-ZnO-Na(2)O-Li(2)O have been prepared and characterized for their thermal, structural and optical properties. Differential thermal analysis revealed reasonably good forming tendency of the glass composition. FTIR spectra were used to analyze the functional groups present in the glass. Judd-Ofelt intensity parameters were derived from the absorption spectrum and used to calculate the radiative lifetime, branching ratio and stimulated emission cross-section for (4)F(3/2)-->(4)I(9/2, 11/2, 13/2) transitions. The quantum efficiency of the (4)F(3/2) level is comparable to the typical values obtained for the Nd(2)O(3)-doped glasses. The decay properties for higher concentration of Nd(2)O(3) were analyzed using Inokuti-Hirayama model to investigate the non-radiative relaxation of the (4)F(3/2) emitting level. The experimental values of branching ratio and saturation intensity of (4)F(3/2)-->(4)I(11/2) transition and calculated spectroscopic quality factor indicate the favourable lasing action in these glasses.

  15. Analysis of a 10 megawatt space-based solar-pumped neodymium laser system

    NASA Technical Reports Server (NTRS)

    Kurweg, U. H.

    1984-01-01

    A ten megawatt solar-pumped continuous liquid laser system for space applications is examined. It is found that a single inflatable mirror of 434 m diameter used in conjunction with a conical secondary concentrator is sufficient to side pump a liquid neodymium lasant in an annular tube of 6 m length and 1 m outer and 0.8 m inner diameter. About one fourth of intercepted radiation converging on the laser tube is absorbed and one fifth of this radiation is effective in populating the upper levels. The liquid lasant is flowed through the annular laser cavity at 1.9 m/s and is cooled via a heat exchanger and a large radiator surface comparable in size to the concentrating mirror. The power density of incident light within the lasant of approximately 68 watt/cu cm required for cw operation is exceeded in the present annular configuration. Total system weight corresponds to 20,500 kg and is thus capable of being transported to near Earth orbit by a single shuttle flight.

  16. Power scaling of diode-pumped neodymium yttrium aluminum borate laser

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid

    1991-01-01

    Preliminary results are presented of the efficient diode-pumped operation of a neodymium yttrium aluminum borate (NYAB) laser at 531.5 nm using two 1-W diode-laser arrays for the pump. With 1380 mW of CW power incident on the crystal, as much as 51 mW of 532.5-nm laser radiation was obtained with the unoptimized cavity. The corresponding optical-to-optical conversion efficiency was 3.7 percent. A plot of the output 531.5 nm vs incident 807 nm pump power is shown. The crystal output power was critically dependent on the rotational and translational adjustment of the NYAB crystal inside the cavity. It is suggested that a crystal cut at the exact phase matching angle, placed in a cavity with proper optimal reflection and transmission mirror coatings, and pumped at proper wavelength can result in higher output power. Thus, the NYAB output power approaches that of a CW intracavity frequency doubled Nd:YAG laser.

  17. High-mobility thin film transistors with neodymium-substituted indium oxide active layer

    SciTech Connect

    Lin, Zhenguo; Lan, Linfeng Xiao, Peng; Sun, Sheng; Li, Yuzhi; Song, Wei; Gao, Peixiong; Wang, Lei; Ning, Honglong; Peng, Junbiao

    2015-09-14

    Thin-film transistors (TFTs) with neodymium-substituted indium oxide (InNdO) channel layer were demonstrated. The structural properties of the InNdO films as a function of annealing temperature have been analyzed using X-ray diffraction and transmission electron microscopy. The InNdO thin films showed polycrystalline nature when annealed at 450 °C with a lattice parameter (cubic cell) of 10.255 Å, which is larger than the cubic In{sub 2}O{sub 3} film (10.117 Å). The high-resolution transmission electron microscopy and energy dispersive X-ray spectroscopy showed that no Nd{sub 2}O{sub 3} clusters were found in the InNdO film, implying that Nd was incorporated into the In{sub 2}O{sub 3} lattice. The InNdO TFTs annealed at 450 °C exhibited more excellent electrical properties with a high mobility of 20.4 cm{sup 2} V{sup −1} s{sup −1} and better electric bias stability compared to those annealed at 300 °C, which was attributed to the reduction of the scattering centers and/or charge traps due to the decrease of the |Nd3d{sub 5/2}{sup 5}4f{sup 4}O2p{sup −1}〉 electron configuration.

  18. Highly efficient neodymium:yttrium aluminum garnet laser end pumped by a semiconductor laser array

    NASA Technical Reports Server (NTRS)

    Sipes, D. L.

    1985-01-01

    In recent experiments, 80-mW CW power in a single mode has been achieved from a neodymium:yttrium aluminum garnet (Nd:YAG) laser with only 1 W of electrical power input to a single semiconductor laser array pump. This corresponds to an overall efficiency of 8 percent, the highest reported CW efficiency for a Nd:YAG laser. A tightly focused semiconductor laser end pump configuration is used to achieve high pumping intensities (on the order of 1 kW/sq cm), which in turn causes the photon to photon conversion efficiency to approach the quantum efficiency (76 percent for Nd:YAG at 1.06 microns pumped at 0.810 micron). This is achieved despite the dual-lobed nature of the pump. Through the use of simple beam-combining schemes (e.g., polarization coupling and multireflection point pumping), output powers over 1 W and overall electrical to optical efficiencies as high as 10 percent are expected.

  19. Design and optimization of arrays of neodymium iron boron-based magnets for magnetic tweezers applications

    NASA Astrophysics Data System (ADS)

    Zacchia, Nicholas A.; Valentine, Megan T.

    2015-05-01

    We present the design methodology for arrays of neodymium iron boron (NdFeB)-based magnets for use in magnetic tweezers devices. Using finite element analysis (FEA), we optimized the geometry of the NdFeB magnet as well as the geometry of iron yokes designed to focus the magnetic fields toward the sample plane. Together, the magnets and yokes form a magnetic array which is the basis of the magnetic tweezers device. By systematically varying 15 distinct shape parameters, we determined those features that maximize the magnitude of the magnetic field gradient as well as the length scale over which the magnetic force operates. Additionally, we demonstrated that magnetic saturation of the yoke material leads to intrinsic limitations in any geometric design. Using this approach, we generated a compact and light-weight magnetic tweezers device that produces a high field gradient at the image plane in order to apply large forces to magnetic beads. We then fabricated the optimized yoke and validated the FEA by experimentally mapping the magnetic field of the device. The optimization data and iterative FEA approach outlined here will enable the streamlined design and construction of specialized instrumentation for force-sensitive microscopy.

  20. Near-infrared electroluminescence at room temperature from neodymium-doped gallium nitride thin films

    SciTech Connect

    Kim, Joo Han; Holloway, Paul H.

    2004-09-06

    Strong near-infrared (NIR) electroluminescence (EL) at room temperature from neodymium (Nd)-doped gallium nitride (GaN) thin films is reported. The Nd-doped GaN films were grown by radio-frequency planar magnetron cosputtering of separate GaN and metallic Nd targets in a pure nitrogen ambient. X-ray diffraction data did not identify the presence of any secondary phases and revealed that the Nd-doped GaN films had a highly textured wurtzite crystal structure with the c-axis normal to the surface of the film. The EL devices were fabricated with a thin-film multilayered structure of Al/Nd-doped GaN/Al{sub 2}O{sub 3}-TiO{sub 2}/indium-tin oxide and tested at room temperate. Three distinct NIR EL emission peaks were observed from the devices at 905, 1082, and 1364 nm, arising from the radiative relaxation of the {sup 4}F{sub 3sol2} excited-state energy level to the {sup 4}I{sub 9sol2}, {sup 4}I{sub 11sol2}, and {sup 4}I{sub 13sol2} levels of the Nd{sup 3+} ion, respectively. The threshold voltage for all the three emission peaks was {approx}150 V. The external power efficiency of the fabricated EL devices was {approx}1x10{sup -5} measured at 40 V above the threshold voltage.

  1. PENTAMETHYLCYCLOPENTADIENYL DERIVATIVES OF THE TRIVALENT LANTHANIDE ELEMENTS (NEODYMIUM, SAMARIUM, AND YTTERBIUM)

    SciTech Connect

    Tilley, T. Don; Andersen, R.A.

    1980-07-01

    The anionic complexes of the type (ML{sub x})(Me{sub 5}C{sub 5}){sub 2}M'Cl{sub 2}, where M is lithium or sodium, L is diethyl ether or N,N,-N{prime},N{prime}-tetramethylethylenediamine, and M{prime} is neodymium, samarium, or ytterbium, have been prepared from the metal trichlorides and the pentamethylcyclopentadienide anion. The neutral species (Me{sub 5}C{sub 5}){sub 2}NdCl(THF), (Me{sub 5}C{sub 5}){sub 2}NdN(SiMe{sub 3}){sub 2}, and (Me{sub 5}C{sub 5}){sub 2}YbCl(THF) have also been prepared. The mono-ring derivatives (Na(OEt{sub 2}){sub 2})((C{sub 5}Me{sub 5})NdCl{sub 3}) and (Me{sub 5}C{sub 5})Nd(N(SiMe{sub 3}){sub 2}){sub 2} are also described.

  2. Bleb reduction using combined photodisruptive and photocoagulative neodymium-doped yttrium-aluminum-garnet laser

    PubMed Central

    Kumar, Harsh; Dangda, Sonal

    2016-01-01

    This case report aims to highlight the role of photodisruptive neodymium-doped yttrium-aluminum-garnet (Nd:YAG) (1064 nm) laser in the treatment of bleb dysesthesia, which occurs in overhanging blebs or with perilimbal spread. Although treatment of such dysesthetic blebs with laser photocoagulation has been previously described, cases where the height of bleb precludes laser penetration, desired effect might not be seen. We herein describe a technique using a combination of photocoagulative (532 nm) and photodisruptive (1064 nm) Nd:YAG laser for a high bleb migrating nasally and inferiorly along the limbus in a 64-year-old female, causing hypotony and consequent macular edema. Successful reduction could be achieved within a week of treatment. By 6 weeks, intraocular pressure improved to 8 mmHg, macular edema subsided, and visual acuity improved to 6/6. Although surgical procedures to correct bleb dysesthesia are available, laser procedures being quick outpatient modalities are more comfortable for the patients. PMID:28112138

  3. Temporal stability of the neodymium isotope signature of the Holocene to glacial North Atlantic

    NASA Astrophysics Data System (ADS)

    van de Flierdt, Tina; Robinson, Laura F.; Adkins, Jess F.; Hemming, Sidney R.; Goldstein, Steven L.

    2006-12-01

    The neodymium isotopic composition of marine precipitates is increasingly recognized as a powerful tool for identifying changes in ocean circulation and mixing on million year to millennial timescales. Unlike nutrient proxies such as δ13C or Cd/Ca, Nd isotopes are not thought to be altered in any significant way by biological processes, and thus they can serve as a quasi-conservative water mass tracer. However, the application of Nd isotopes in understanding the role of thermohaline circulation in rapid climate change is currently hindered by the lack of direct constraints on the signature of the North Atlantic end-member through time. Here we present the first results of Nd isotopes measured in U-Th-dated deep-sea corals from the New England seamounts in the northwest Atlantic Ocean. Our data are consistent with the conclusion that the Nd isotopic composition of North Atlantic deep and intermediate water has remained nearly constant through the last glacial cycle. The results address long-standing concerns that there may have been significant changes in the Nd isotopic composition of the North Atlantic end-member during this interval and substantiate the applicability of this novel tracer on millennial timescales for paleoceanography research.

  4. Planar waveguides in neodymium-doped calcium niobium gallium garnet crystals produced by proton implantation

    NASA Astrophysics Data System (ADS)

    Chun-Xiao, Liu; Meng, Chen; Li-Li, Fu; Rui-Lin, Zheng; Hai-Tao, Guo; Zhi-Guang, Zhou; Wei-Nan, Li; She-Bao, Lin; Wei, Wei

    2016-04-01

    In this work, the fabrication and optical properties of a planar waveguide in a neodymium-doped calcium niobium gallium garnet (Nd:CNGG) crystal are reported. The waveguide is produced by proton (H+) implantation at 480 keV and a fluence of 1.0×1017 ions/cm2. The prism-coupling measurement is performed to obtain the dark mode of the waveguide at a wavelength of 632.8 nm. The reflectivity calculation method (RCM) is used to reconstruct the refractive index profile. The finite-difference beam propagation method (FD-BPM) is employed to calculate the guided mode profile of the waveguide. The stopping and range of ions in matter 2010 (SRIM 2010) code is used to simulate the damage profile induced by the ion implantation. The experimental and theoretical results indicate that the waveguide can confine the light propagation. Project supported by the National Natural Science Foundation of China (Grant Nos. 11405041, 61405240, 61077070, 61177086, 51002181, and 61177084), the Scientific Research Starting Foundation for New Teachers of Nanjing University of Posts and Telecommunications (NUPTSF) (Grant No. NY214159), and the Research Center of Optical Communications Engineering & Technology, Jiangsu Province, China (Grant No. ZSF0401).

  5. Optical constants determination of neodymium and gadolinium in the 3-nm to 100-nm wavelength range

    NASA Astrophysics Data System (ADS)

    Kjornrattanawanich, B.; Windt, D. L.; Uspenskii, Y. A.; Seely, J. F.

    2006-08-01

    The optical constants (n, k) of the wavelength-dependent index of refraction N = n+ik = 1-δ+ik of Nd (Neodymium) and Gd (Gadolinium) are determined in the wavelength range of 3 nm to 100 nm by the transmittance method using synchrotron radiation. Nd and Gd films with thicknesses ranging from 5 nm to 180 nm were fabricated on Si photodiodes (which served as the coating substrates as well as the detectors) and capped with Si layers to protect these reactive rare earth elements from oxidation. The imaginary part (k) obtained directly from the transmittance measurement is used in the derivation of the real part (δ) of the complex index of refraction N through the Kramers- Kronig integral. The measured optical constants are used in the design of currently developed Nd- and Gd-based multilayers for solar imaging applications. Our results on Nd and Gd optical constants and the reflectance of some Nd- and Gd-based multilayers are presented.

  6. Laser treatment of a neodymium magnet and analysis of surface characteristics

    NASA Astrophysics Data System (ADS)

    Yilbas, B. S.; Ali, H.; Rizwan, M.; Kassas, M.

    2016-08-01

    Laser treatment of neodymium magnet (Nd2Fe14B) surface is carried out under the high pressure nitrogen assisting gas. A thin carbon film containing 12% WC carbide particles with 400 nm sizes are formed at the surface prior to the laser treatment process. Morphological and metallurgical changes in the laser treated layer are examined using the analytical tools. The corrosion resistance of the laser treated surface is analyzed incorporating the potentiodynamic tests carried out in 0.05 M NaCl+0.1 M H2SO4 solution. The friction coefficient of the laser treated surface is measured using the micro-scratch tester. The wetting characteristics of the treated surface are assessed incorporating the sessile water drop measurements. It is found that a dense layer consisting of fine size grains and WC particles is formed in the surface region of the laser treated layer. Corrosion resistance of the surface improves significantly after the laser treatment process. Friction coefficient of laser treated surface is lower than that of the as received surface. Laser treatment results in superhydrophobic characteristics at the substrate surface. The formation of hematite and grain size variation in the treated layer slightly lowers the magnetic strength of the laser treated workpiece.

  7. Biosorption of neodymium on Chlorella vulgaris in aqueous solution obtained from hard disk drive magnets

    PubMed Central

    Kucuker, Mehmet Ali; Wieczorek, Nils; Kuchta, Kerstin; Copty, Nadim K.

    2017-01-01

    In recent years, biosorption is being considered as an environmental friendly technology for the recovery of rare earth metals (REE). This study investigates the optimal conditions for the biosorption of neodymium (Nd) from an aqueous solution derived from hard drive disk magnets using green microalgae (Chlorella vulgaris). The parameters considered include solution pH, temperature and biosorbent dosage. Best-fit equilibrium as well as kinetic biosorption models were also developed. At the optimal pH of 5, the maximum experimental Nd uptakes at 21, 35 and 50°C and an initial Nd concentration of 250 mg/L were 126.13, 157.40 and 77.10 mg/g, respectively. Analysis of the optimal equilibrium sorption data showed that the data fitted well (R2 = 0.98) to the Langmuir isotherm model, with maximum monolayer coverage capacity (qmax) of 188.68 mg/g, and Langmuir isotherm constant (KL) of 0.029 L/mg. The corresponding separation factor (RL) is 0.12 indicating that the equilibrium sorption was favorable. The sorption kinetics of Nd ion follows well a pseudo-second order model (R2>0.99), even at low initial concentrations. These results show that Chlorella vulgaris has greater biosorption affinity for Nd than activated carbon and other algae types such as: A. Gracilis, Sargassum sp. and A. Densus. PMID:28388641

  8. Efficient eye-safe neodymium doped composite yttrium gallium garnet crystal laser.

    PubMed

    Yu, Haohai; Wang, Shuxian; Han, Shuo; Wu, Kui; Su, Liangbi; Zhang, Huaijin; Wang, Zhengping; Xu, Jun; Wang, Jiyang

    2014-03-15

    We report a laser-diode pumped continuous-wave (cw) and passively Q-switched eye-safe laser at about 1.42 μm with the neodymium-doped yttrium gallium garnet (Nd:YGG) crystal for the first time to our knowledge. The composite Nd:YGG crystal was developed originally. A systematic comparison of laser performance between the homogeneously doped and composite Nd:YGG crystal was made, which showed that the composite Nd:YGG manifested less thermally induced effects. Cw output power of 2.06 W was obtained with the slope efficiency of 20.7%. With a V:YAG as a saturable absorber, the passive Q-switching at 1.42 μm was gotten with the pulse width, pulse energy, and peak power of 34 ns, 46.7 μJ, and 1.4 kW, respectively. The present work should provide a potential candidate for the generation of eye-safe lasers.

  9. A new solid-state, frequency-doubled neodymium-YAG photocoagulation system.

    PubMed

    Jalkh, A E; Pflibsen, K; Pomerantzeff, O; Trempe, C L; Schepens, C L

    1988-06-01

    We have developed a solid-state laser system that produces a continuous green monochromatic laser beam of 532 nm by doubling the frequency of a neodymium-YAG laser wavelength of 1064 nm with a potassium-titamyl-phosphate crystal. Photocoagulation burns of equal size and intensity were placed in two rabbit eyes with the solid-state laser system and the regular green argon laser system, respectively, using the same slit-lamp mode of delivery. Histologic findings of lesion sections revealed no important differences between the two systems. In theory, the longer wavelength of the solid-state laser offers the advantages of less scattering in ocular media, higher absorption by oxyhemoglobin, and less absorption by macular xanthophyll than the 514-nm wavelength of the regular green argon laser. The solid-state laser has impressive technical advantages: it contains no argon-ion gas tube that wears out and is expensive to replace; it is much more power efficient, and thus considerably smaller and compact; it is sturdier and easily movable; it does not require external cooling; it uses a 220-V monophasic alternating current; and it requires little maintenance.

  10. Constraints on ocean circulation at the Paleocene-Eocene Thermal Maximum from neodymium isotopes

    NASA Astrophysics Data System (ADS)

    Abbott, April N.; Haley, Brian A.; Tripati, Aradhna K.; Frank, Martin

    2016-04-01

    Global warming during the Paleocene-Eocene Thermal Maximum (PETM) ˜ 55 million years ago (Ma) coincided with a massive release of carbon to the ocean-atmosphere system, as indicated by carbon isotopic data. Previous studies have argued for a role of changing ocean circulation, possibly as a trigger or response to climatic changes. We use neodymium (Nd) isotopic data to reconstruct short high-resolution records of deep-water circulation across the PETM. These records are derived by reductively leaching sediments from seven globally distributed sites to reconstruct past deep-ocean circulation across the PETM. The Nd data for the leachates are interpreted to be consistent with previous studies that have used fish teeth Nd isotopes and benthic foraminiferal δ13C to constrain regions of convection. There is some evidence from combining Nd isotope and δ13C records that the three major ocean basins may not have had substantial exchanges of deep waters. If the isotopic data are interpreted within this framework, then the observed pattern may be explained if the strength of overturning in each basin varied distinctly over the PETM, resulting in differences in deep-water aging gradients between basins. Results are consistent with published interpretations from proxy data and model simulations that suggest modulation of overturning circulation had an important role for initiation and recovery of the ocean-atmosphere system associated with the PETM.

  11. Efficient graphene Q switching and mode locking of 1.34 μm neodymium lasers.

    PubMed

    Xu, Jin-Long; Li, Xian-Lei; He, Jing-Liang; Hao, Xiao-Peng; Yang, Ying; Wu, Yong-Zhong; Liu, Shan-De; Zhang, Bai-Tao

    2012-07-01

    We demonstrate that few-layered graphene sheets used as a saturable absorber can provide efficient Q-switching and mode-locking modulation in 1.34 μm Nd:GdVO(4) bulk lasers. The minimum Q-switched pulses were 450 ns for 260 mW average power, 43 kHz repetition rate, and 2.5 μJ pulse energy. For the mode-locked laser, an average power of 1.29 W was achieved with 11 ps pulse duration and 13 nJ pulse energy. To our knowledge, this average power is the highest yet obtained from a graphene mode-locked laser, and the corresponding optical-optical efficiency of 23% is the best result among 1.3 μm neodymium mode-locked lasers. The quality factor M(2) of the Q-switched beam was 1.4 and 1.6 in the horizontal and longitudinal planes, respectively, and the M(2) of the mode-locked beam reached 1.1 and 1.0. These results clearly indicate the advantages of few-layered graphene as a saturable absorber.

  12. Posterior capsule opacification and neodymium: YAG capsulotomy with heparin-surface-modified intraocular lenses.

    PubMed

    Winther-Nielson, A; Johansen, J; Pedersen, G K; Corydon, L

    1998-07-01

    To compare the effect of heparin-surface-modified (HSM) and conventional unmodified poly(methyl methacrylate) (PMMA) intraocular lenses (IOLs) on the formation of posterior capsule opacification (PCO). Department of Ophthalmology, Vejle Hospital, Denmark. This prospective, randomized, double-blind study comprised 250 eyes of 246 patients who had uneventful extracapsular cataract extraction in otherwise healthy eyes with implantation of a biconvex IOL or a convex-plano lens with a continuous laser ridge. Patients were examined once a year for 3 years, at which time the degree of PCO was recorded. A neodymium:YAG laser capsulotomy was performed if certain criteria were met. The incidence of PCO was statistically significantly higher in eyes with an HSM convex-plano laser-ridge IOL than in those with an unmodified convex-plano lens (P < .005). There were no significant differences between any other groups. The incidence of PCO was higher in eyes with an HSM convex-plano IOL with a laser ridge.

  13. Subtotal canine prostatectomy with the neodymium: yttrium-aluminum-garnet laser.

    PubMed

    Hardie, E M; Stone, E A; Spaulding, K A; Cullen, J M

    1990-01-01

    A technique was developed for subtotal prostatectomy in dogs with the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser. In six normal dogs, full-thickness necrosis of the prostate occurred if the central-lateral region within 5 mm of the urethra was photoablated at 60 watts for 1 second. Moderate to superficial necrosis occurred when the prostate within 5 mm of the urethra was photoablated at 35 watts for 2 seconds or 60 watts for 0.5 second. At necropsy, leakage of the urethra occurred in two dogs at sites treated at 60 watts for 1 second. In a clinical study, complications associated with subtotal prostatectomy with the Nd:YAG laser (n = 6) were compared with complications associated with prostatic drainage (n = 6) in dogs with prostatic disease. Intraoperative death (2/6 dogs) and nocturnal incontinence (4/4 surviving dogs) occurred with subtotal prostatectomy. Uncontrolled prostatic infection (2/6 dogs) occurred with prostatic drainage and resulted in the death of one dog on day 11. Four of five dogs surviving prostatic drainage developed recurrent urinary tract infection.

  14. Refractory open-angle glaucoma after neodymium-yttrium-aluminum-garnet laser lysis of vitreous floaters.

    PubMed

    Cowan, Lisa A; Khine, Kay T; Chopra, Vikas; Fazio, Doreen T; Francis, Brian A

    2015-01-01

    To illustrate 3 cases of chronic open-angle glaucoma secondary to the neodymium-yttrium-aluminum-garnet (Nd:YAG) laser vitreolysis procedure for symptomatic vitreous floaters. Observational case series. Location of the study was the Doheny Eye Institute. Three eyes of 2 patients who developed chronic open-angle glaucoma after Nd:YAG vitreolysis for symptomatic floaters presenting with very high intraocular pressure (IOP >40 mm Hg) were selected. The time from the laser treatment to the onset of elevated pressure ranges from 1 week to 8 months. There was no associated inflammation, steroid use, or other identifiable cause of chronic IOP elevation. All eyes were treated initially with glaucoma medication, followed by selective laser trabeculoplasty (SLT) and eventually glaucoma surgery (Trabectome) in 2 eyes for disease management. In all eyes, intraocular pressures were eventually stabilized within a normal pressure range from 18 to 38 months following Nd:YAG vitreolysis. At the latest follow-up post surgery, all eyes had intraocular pressures of 22 mm Hg or less with or without medications. Secondary open-angle glaucoma is a complication of Nd:YAG vitreolysis for symptomatic floaters that may present with an increase in intraocular pressure immediately, or many months after the surgery. Furthermore this complication may be permanent and require chronic medical therapy or glaucoma surgery. Copyright © 2015 Elsevier Inc. All rights reserved.

  15. Morphological changes in human skin melanoma treated by high-energy pulsed neodymium laser radiation.

    PubMed

    Moskalik, K G; Alexeeva, L N; Novik, V I; Demin, E V; Kozlov, A P

    2011-01-01

    The neodymium (Nd) laser irradiation has been successfully applied to the treatment of slightly elevated skin melanoma. At the same time the histologic aspects of such a treatment have not been precisely investigated. The aim of this study was to retrace the histological features in human primary cutaneous melanomas after 1060 nm high energy mono pulsed Nd laser treatment in the dynamic healing of the affected tissues. Histologic analysis of cutaneous melanomas irradiated by Nd laser was carried out. Tissue specimens were taken before and immediately after exposure to laser and 1 hour, and 1, 2 and 3 days after wards. Also the wounds that appeared after the scab fell off and the scars formed following laser irradiation were also the subject of histologic analysis at 2, 4 and 6 months post-treatment. The Nd laser irradiation caused coagulation necrosis of melanoma, epidermis and dermis with skin appendices and superficial layers of subcutaneous fatty tissue. Foci of laser destruction were characterized by strict locality and efficient separation from the adjacent tissues, by the presence of stasis, thrombosis and coagulation of blood and lymphatic vessels. There was an increase of lymphocytes, macrophages and histiocytes in the area damaged by laser as well as in wounds and scars. The pulsed Nd laser induces acute photothermal damages of melanoma tissue, which differs from the usual thermal lesions and the most critical difference of the effect of this modality is gain of immunocompetent cells in the affected tissue after laser beam application.

  16. Treatment of onychomycosis using a submillisecond 1064-nm neodymium:yttrium-aluminum-garnet laser.

    PubMed

    Carney, Caitlin; Cantrell, Wendy; Warner, Judy; Elewski, Boni

    2013-10-01

    Laser treatment has emerged as a novel treatment modality for onychomycosis. We sought to determine thermal response and optical effects of a submillisecond neodymium:yttrium-aluminum-garnet (Nd:YAG) 1064-nm laser on common fungal nail pathogens, and the clinical efficacy and safety of the Nd:YAG 1064-nm laser on onychomycotic toenails. A 4-part in vitro and in vivo study was conducted using a Nd:YAG 1064-nm laser. The first portion evaluated 3 different nail pathogens in suspension at 7 heat and time exposures. The second and third parts of the study irradiated pure fungal colonies. The final portion involved an in vivo treatment of toenails over 5 treatment sessions. A fungicidal effect for Trichophyton rubrum was seen at 50°C after 15 minutes, and for Epidermophyton floccosum at 50°C after 10 minutes. Limited growth of Scytalidium was seen at 55°C after 5 minutes. No inhibition was observed after laser treatment of fungal colonies or suspensions. In vivo treatment of toenails showed no improvement in Onychomycosis Severity Index score. The Nd:YAG 1064-nm laser was the only laser tested. Laser treatment of onychomycosis was not related to thermal damage or direct laser effects. In vivo treatment did not result in onychomycosis cure. Copyright © 2013 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.

  17. Biosorption of neodymium on Chlorella vulgaris in aqueous solution obtained from hard disk drive magnets.

    PubMed

    Kucuker, Mehmet Ali; Wieczorek, Nils; Kuchta, Kerstin; Copty, Nadim K

    2017-01-01

    In recent years, biosorption is being considered as an environmental friendly technology for the recovery of rare earth metals (REE). This study investigates the optimal conditions for the biosorption of neodymium (Nd) from an aqueous solution derived from hard drive disk magnets using green microalgae (Chlorella vulgaris). The parameters considered include solution pH, temperature and biosorbent dosage. Best-fit equilibrium as well as kinetic biosorption models were also developed. At the optimal pH of 5, the maximum experimental Nd uptakes at 21, 35 and 50°C and an initial Nd concentration of 250 mg/L were 126.13, 157.40 and 77.10 mg/g, respectively. Analysis of the optimal equilibrium sorption data showed that the data fitted well (R2 = 0.98) to the Langmuir isotherm model, with maximum monolayer coverage capacity (qmax) of 188.68 mg/g, and Langmuir isotherm constant (KL) of 0.029 L/mg. The corresponding separation factor (RL) is 0.12 indicating that the equilibrium sorption was favorable. The sorption kinetics of Nd ion follows well a pseudo-second order model (R2>0.99), even at low initial concentrations. These results show that Chlorella vulgaris has greater biosorption affinity for Nd than activated carbon and other algae types such as: A. Gracilis, Sargassum sp. and A. Densus.

  18. Clinical comparison of semiconductor diode versus neodymium: YAG non-contact cyclo photocoagulation.

    PubMed Central

    Ulbig, M W; McHugh, D A; McNaught, A I; Hamilton, A M

    1995-01-01

    AIMS--The advent of diode lasers has allowed their use in transscleral cyclo photocoagulation for refractory glaucoma. A trial was performed to compare the ocular hypotensive and inflammatory effects of cyclo photocoagulation using a continuous wave diode (810 nm) and a free running neodymium:yttrium aluminium garnet (Nd:YAG) laser (1064 nm). METHODS--Forty patients with refractory glaucoma were randomised to receive either diode or Nd:YAG therapy. The intraocular pressure (IOP) and inflammatory response to treatment were monitored over 3 months. RESULTS--There was no significant laser related difference in the effect on IOP after one treatment. There was, however, a difference in effect in retreatments with the IOP lowering effect significantly less, but equally sustained in diode retreatment patients. Severe postoperative complications such as hyphaema or fibrinous anterior uveitis only occurred in the Nd:YAG group. CONCLUSION--The degree and duration of the ocular hypotensive response to cyclo photocoagulation appears to be related to the available power output of the system used, and the extent of tissue damage. Images PMID:7626573

  19. Influence of size of neodymium:yttrium-aluminium-garnet laser posterior capsulotomy on visual function.

    PubMed

    Hayashi, K; Nakao, F; Hayashi, H

    2010-01-01

    The aim of this study was to examine the influence that the size of a neodymium:yttrium-aluminium-garnet (Nd:YAG) laser capsulotomy performed for posterior capsule opacification (PCO) has on visual acuity (VA), and on contrast VA and that in the presence of glare (glare VA). A total of 41 consecutive eyes with PCO first underwent Nd:YAG laser capsulotomy of smaller than pupillary size, after which the capsulotomy was secondarily enlarged, 2 weeks later, to greater than pupillary size. Best-corrected VA, and contrast VA and glare VA under photopic and mesopic conditions were measured after the small and large capsulotomies were made. After enlargement, the mean capsulotomy area increased significantly from 4.8 to 15.3 mm(2) (P<0.0001). Best-corrected VA did not improve significantly after enlargement (P=0.1282). However, photopic contrast VA and glare VA at moderate to low contrast visual target before enlargement were significantly worse than those after enlargement (P

  20. Application of neodymium isotope ratio measurements for the origin assessment of uranium ore concentrates.

    PubMed

    Krajkó, Judit; Varga, Zsolt; Yalcintas, Ezgi; Wallenius, Maria; Mayer, Klaus

    2014-11-01

    A novel procedure has been developed for the measurement of (143)Nd/(144)Nd isotope ratio in various uranium-bearing materials, such as uranium ores and ore concentrates (UOC) in order to evaluate the usefulness and applicability of variations of (143)Nd/(144)Nd isotope ratio for provenance assessment in nuclear forensics. Neodymium was separated and pre-concentrated by extraction chromatography and then the isotope ratios were measured by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS). The method was validated by the measurement of standard reference materials (La Jolla, JB-2 and BCR-2) and the applicability of the procedure was demonstrated by the analysis of uranium samples of world-wide origin. The investigated samples show distinct (143)Nd/(144)Nd ratio depending on the ore type, deposit age and Sm/Nd ratio. Together with other characteristics of the material in question, the Nd isotope ratio is a promising signature for nuclear forensics and suggests being indicative of the source material, the uranium ore.

  1. Natural Weathering Rates of Silicate Minerals

    NASA Astrophysics Data System (ADS)

    White, A. F.

    2003-12-01

    Silicates constitute more than 90% of the rocks exposed at Earth's land surface (Garrels and Mackenzie, 1971). Most primary minerals comprising these rocks are thermodynamically unstable at surface pressure/temperature conditions and are therefore susceptible to chemical weathering. Such weathering has long been of interest in the natural sciences. Hartt (1853) correctly attributed chemical weathering to "the efficacy of water containing carbonic acid in promoting the decomposition of igneous rocks." Antecedent to the recent interest in the role of vegetation on chemical weathering, Belt (1874) observed that the most intense weathering of rocks in tropical Nicaragua was confined to forested regions. He attributed this effect to "the percolation through rocks of rain water charged with a little acid from decomposing vegetation." Chamberlin (1899) proposed that the enhanced rates of chemical weathering associated with major mountain building episodes in Earth's history resulted in a drawdown of atmospheric CO2 that led to periods of global cooling. Many of the major characteristics of chemical weathering had been described when Merrill (1906) published the groundbreaking volume Rocks, Rock Weathering, and Soils.The major advances since that time, particularly during the last several decades, have centered on understanding the fundamental chemical, hydrologic, and biologic processes that control weathering and in establishing quantitative weathering rates. This research has been driven by the importance of chemical weathering to a number environmentally and economically important issues. Undoubtedly, the most significant aspect of chemical weathering is the breakdown of rocks to form soils, a process that makes life possible on the surface of the Earth. The availability of many soil macronutrients such as magnesium, calcium, potassium, and PO4 is directly related to the rate at which primary minerals weather. Often such nutrient balances are upset by anthropogenic

  2. Steps toward interstellar silicate mineralogy. V. Thermal Evolution of Amorphous Magnesium Silicates and Silica

    NASA Astrophysics Data System (ADS)

    Fabian, D.; Jäger, C.; Henning, Th.; Dorschner, J.; Mutschke, H.

    2000-12-01

    The thermally induced amorphous-to-crystalline transition has been studied for bulk sheets and micrometre-sized particles of magnesium silicate glass (MgSiO3), nanometre-sized amorphous magnesium silicate (MgSiO3 and Mg2SiO4 smokes) and amorphous silica particles (SiO2). Silicate glass was produced by the shock-quenching of melts. Samples of nanometre-sized smoke particles have been obtained by the laser ablation technique. Both the MgSiO3 and the Mg2SiO4 smokes have been found to consist of two particle species; particles of smaller size ranging in diametre from 10 nm to about 100 nm and bigger size ranging from a few 100 nm to almost 3 micrometres in diametre. Nanometre-sized particles have been shown to be depleted in magnesium whereas the micrometre-sized particles were found to be enriched in Mg. Generally, the particles are composed of nonstoichiometric magnesium silicates with compositions varying even inside of the particles. Frequently, the particles contained internal voids that are assumed to have been formed by thermal shrinkage or outgassing of the particles' interior during cooling. Annealing at 1000 K transformed the magnesium silicate smokes into crystalline forsterite (c-Mg2SiO4), tridymite (a crystalline modification of SiO2) and amorphous silica (a-SiO2) according to the initial Mg/Si-ratio of the smoke. Crystallization took place within a few hours for the Mg2SiO4 smoke and within one day for the MgSiO3 smoke. The MgSiO3 glass evolved more slowly because crystallization started at the sample surface. It has been annealed at temperatures ranging from 1000 to 1165 K. In contrast to the smoke samples, MgSiO3 glass crystallized as orthoenstatite (MgSiO3). Only after 50 hours of annealing at 1000 K, weak indications of forsterite and tridymite formation have been found in the X-ray diffraction spectra. At a temperature of 1000 K, amorphous silica nanoparticles showed distinctly lower rates of thermal evolution compared with the magnesium silicates

  3. SILICATES FOR CORROSION CONTROL IN BUILDING POTABLE WATER SYSTEMS

    EPA Science Inventory

    Silicates have been used to control the corrosion of drinking water distribution system materials. Previous work has shown that they are particularly useful in reducing the release of zinc from galvanized materials in hot water systems. Negatively charged silicate species were re...

  4. Grain properties of crystalline silicate in Oort cloud comets II

    NASA Astrophysics Data System (ADS)

    Ootsubo, Takafumi

    2014-01-01

    Crystalline silicate is sometimes observed in comets as an 11.3-micron resonant emission feature, and may be used for probing the early solar nebula. Because the formation of the crystalline silicate grains requires high temperature, they are thought to be born from amorphous silicates at the inner region, and then transported toward the outer region where comets were born. This transportation can produce the difference in the fraction of crystalline silicate in the cometary dust between two dynamical types of comets, Oort-cloud comets (OCs) and Ecliptic comets (ECs), due to the different heliocentric distances of their birth places. Recently, it is suggested that infrared spectra and peak wavelengths of silicate (forsterite) features depend on particle shapes. From this point of view, peak wavelengths of crystalline silicate features in comet spectra are important to investigate the conditions of the crystalline silicate formation in the early solar nebula. Fortunately, we can observe the comet C/2012 K1 (PanSTARRS) along with C/2012 X1 (LINEAR) in this semester. In particular, the comet C/2012 K1 is a bright and good target for this silicate peak feature study.

  5. 78 FR 14540 - Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-03-06

    ... AGENCY Cyromazine, Silica Silicates (Silica Dioxide and Silica Gel), Glufosinate Ammonium, Dioctyl Sodium... the registration review of cyromazine, silica silicates (silica dioxide and silica gel), glufosinate...). Silica silicates, silicon dioxide and silica gel, are insecticides and acaracides used in...

  6. Sensitization of neodymium ion luminescence by chromium ions in a Gd/sub 3/Ga/sub 5/O/sub 12/ crystal

    SciTech Connect

    Zharikov, E.V.; Il'ichev, N.N.; Laptev, V.V.; Malyutin, A.A.; Ostroumov, V.G.; Pashinin, P.P.; Shcherbakov, I.A.

    1982-03-01

    An investigation is reported of the spectral, luminescence, and lasing properties of a Gd/sub 3/Ga/sub 5/O/sub 12/ crystal activated with chromium and neodymium ions. The high efficiency of the energy transfer process from chromium to neodymium ions is demonstrated. For example, the probability of an elementary Cr/sup 3 +/--Nd/sup 3 +/ interaction event in a Gd/sub 3/Ga/sub 5/O/sub 12/ crystal was 12 times higher than that in a Y/sub 3/Al/sub 5/O/sub 12/ crystal. It was found that sensitization of neodymium ion luminescence by chromium ions can increase severalfold the energy characteristics of cw and pulsed neodymium lasers. An investigation of the free-lasing parameters shows that the ultimate differential lasing efficiency of neodymium in a Gd/sub 3/Ga/sub 5/O/sub 12/:Cr:Nd crystal is 3.6 times higher than that for a YAG:Nd crystal under comparable conditions.

  7. Laboratory Studies on Silicates Relevant for the Physics of TNOs

    NASA Astrophysics Data System (ADS)

    Brucato, John Robert; Strazzulla, Giovanni; Baratta, Giuseppe; Mennella, Vito; Colangeli, Luigi

    2003-06-01

    Silicates are one of the principal components present in Solar System objects. Silicates evolve in space modifying their physical properties according to the astronomical environments they go through. To characterise the nature of TNOs in the framework of the formation and evolution of the Solar System, experiments on structural transitions of silicates have been performed in the laboratory to simulate some of the processing suffered by the dust. The infrared spectral properties of possible silicate candidates thought to be present in TNOs have been studied. The results of thermal annealing of amorphous silicates and amorphisation of crystalline forsterite (pure-Mg olivine) by ion irradiation are presented. The observable properties of TNOs surfaces are inferred.

  8. Optical Properties of Astronomical Silicates in the Far-infrared

    NASA Technical Reports Server (NTRS)

    Rinehart, Stephen A,; Benford, Dominic J.; Dwek, Eli; Henry, Ross M.; Nuth, Joseph A., III; Silverberg, Robert f.; Wollack, Edward J.

    2008-01-01

    Correct interpretation of a vast array of astronomical data relies heavily on understanding the properties of silicate dust as a function of wavelength, temperature, and crystallinity. We introduce the QPASI-T (Optical Properties of Astronomical Silicates with Infrared Techniques) project to address the need for high fidelity optical characterization data on the various forms of astronomical dust. We use two spectrometers to provide extinction data for silicate samples across a wide wavelength range (from the near infrared to the millimeter). New experiments are in development that will provide complementary information on the emissivity of our samples, allowing us to complete the optical characterization of these dust materials. In this paper, we present initial results from several materials including amorphous iron silicate, magnesium silicate and silica smokes, over a wide range of temperatures, and discuss the design and operation of our new experiments.

  9. Optical Properties of Astronomical Silicates in the Far-infrared

    NASA Technical Reports Server (NTRS)

    Rinehart, Stephen A,; Benford, Dominic J.; Dwek, Eli; Henry, Ross M.; Nuth, Joseph A., III; Silverberg, Robert f.; Wollack, Edward J.

    2008-01-01

    Correct interpretation of a vast array of astronomical data relies heavily on understanding the properties of silicate dust as a function of wavelength, temperature, and crystallinity. We introduce the QPASI-T (Optical Properties of Astronomical Silicates with Infrared Techniques) project to address the need for high fidelity optical characterization data on the various forms of astronomical dust. We use two spectrometers to provide extinction data for silicate samples across a wide wavelength range (from the near infrared to the millimeter). New experiments are in development that will provide complementary information on the emissivity of our samples, allowing us to complete the optical characterization of these dust materials. In this paper, we present initial results from several materials including amorphous iron silicate, magnesium silicate and silica smokes, over a wide range of temperatures, and discuss the design and operation of our new experiments.

  10. The identification of crystalline olivine in cometary silicates

    NASA Technical Reports Server (NTRS)

    Campins, Humberto; Ryan, Eileen V.

    1989-01-01

    An intermediate-resolution spectrum of the 8-13 micron region in comet Halley is obtained which shows a prominent silicate emission feature with structure not observed before in other comets or in interstellar silicates. The presence of a strong 11.3 micron peak reported by Bregman and coworkers is confirmed, and evidence is found for additional structure in the band. By comparison with spectra of interplanetary dust particles and laboratory silicates, it is concluded that small crystalline olivine particles are a major component of the silicates in this comet; other silicates (e.g., amorphous or hydrated) must also be present. The identification of crystalline olivine in this part of the spectrum is supported by the observation of four peaks in 20-50 micron airborne spectra of this comet which have also been attributed to olivine.

  11. Immobilisation of fully sulfonated polyaniline on nanostructured calcium silicate.

    PubMed

    Borrmann, Thomas; Dominis, Anton; McFarlane, Andrew J; Johnston, James H; Richardson, Michael J; Kane-Maguire, Leon A P; Wallace, Gordon G

    2007-12-01

    Up to 7.4% (w/w) of the sulfonated polyaniline, poly(2-methoxyaniline-5-sulfonic acid) (PMAS) can be absorbed onto nanostructured calcium silicates. Spectroscopic and leaching studies on the novel PMAS-silicate nanocomposites obtained indicate that attachment of the PMAS occurs via electrostatic binding of PMAS sulfonate groups to Ca2+ sites on the silicates. The surface area and pore volume of the nanocomposites are comparable to those of pure silicate and increase the surface area of the PMAS polymer by several orders of magnitude. The PMAS emeraldine salt in the nanocomposites retains its chemical reactivity, being readily oxidised and reduced to its pernigraniline and leucoemeraldine forms, respectively. The conductivity of the composite is comparable to that of the pure PMAS, several orders of magnitude higher than that of dried nanostructured calcium silicate.

  12. Silicate Inclusions in the Kodaikanal IIE Iron Meteorite

    NASA Technical Reports Server (NTRS)

    Kurat, G.; Varela, M. E.; Zinner, E.

    2005-01-01

    Silicate inclusions in iron meteorites display an astonishing chemical and mineralogical variety, ranging from chondritic to highly fractionated, silica- and alkali-rich assemblages. In spite of this, their origin is commonly considered to be a simple one: mixing of silicates, fractionated or unfractionated, with metal. The latter had to be liquid in order to accommodate the former in a pore-free way which all models accomplish by assuming shock melting. II-E iron meteorites are particularly interesting because they contain an exotic zoo of silicate inclusions, including some chemically strongly fractionated ones. They also pose a formidable conundrum: young silicates are enclosed by very old metal. This and many other incompatibilities between models and reality forced the formulation of an alternative genetic model for irons. Here we present preliminary findings in our study of Kodaikanal silicate inclusions.

  13. The identification of crystalline olivine in cometary silicates

    NASA Technical Reports Server (NTRS)

    Campins, Humberto; Ryan, Eileen V.

    1989-01-01

    An intermediate-resolution spectrum of the 8-13 micron region in comet Halley is obtained which shows a prominent silicate emission feature with structure not observed before in other comets or in interstellar silicates. The presence of a strong 11.3 micron peak reported by Bregman and coworkers is confirmed, and evidence is found for additional structure in the band. By comparison with spectra of interplanetary dust particles and laboratory silicates, it is concluded that small crystalline olivine particles are a major component of the silicates in this comet; other silicates (e.g., amorphous or hydrated) must also be present. The identification of crystalline olivine in this part of the spectrum is supported by the observation of four peaks in 20-50 micron airborne spectra of this comet which have also been attributed to olivine.

  14. Organics Synthesized Using Iron-Grain Silicates

    NASA Technical Reports Server (NTRS)

    Johnson, N. M.; Cody, G. D.; Nuth, J. A., III

    2003-01-01

    We use Fischer-Tropsch type (FTT) synthesis to produce hydrocarbons by hydrogenating carbon monoxide via catalytic reactions. The products of these reactions have been studied using 'natural' catalysts and calculations of the efficiency of FTT synthesis in the Solar Nebula suggest that these types of reactions could make significant contributions to the composition of material near three AU. We coat Fe-silicate grains with organic material using FTT synthesis to simulate the chemistry in the early Solar Nebula. In our experimental setup, we roughly model a nebular environment where grains are successively transported from hot to cold regions of the nebula. In other words, the starting gases and FTT products are continuously circulated through the grains at high temperature with intervals of cooling. Organics generated in this manner could represent the carbonaceous material incorporated in comets and meteorites. We analyze the resulting organics and present the results.

  15. Thermal Ablation Modeling for Silicate Materials

    NASA Technical Reports Server (NTRS)

    Chen, Yih-Kanq

    2016-01-01

    A general thermal ablation model for silicates is proposed. The model includes the mass losses through the balance between evaporation and condensation, and through the moving molten layer driven by surface shear force and pressure gradient. This model can be applied in the ablation simulation of the meteoroid and the glassy ablator for spacecraft Thermal Protection Systems. Time-dependent axisymmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material response code, Two-dimensional Implicit Thermal Ablation simulation program, to predict the mass lost rates and shape change. The predicted mass loss rates will be compared with available data for model validation, and parametric studies will also be performed for meteoroid earth entry conditions.

  16. Cesium titanium silicate and method of making

    DOEpatents

    Balmer, Mari L.

    1997-01-01

    The invention is the new material, a ternary compound of cesium, silica, and titania, together with a method of making the ternary compound, cesium titanium silicate pollucite. More specifically, the invention is Cs.sub.2 Ti.sub.2 Si.sub.4 O.sub.13 pollucite which is a new crystalline phase representing a novel class of Ti-containing zeolites. Compositions contain relatively high Cs.sub.2 O and TiO.sub.2 loadings and are durable glass and ceramic materials. The amount of TiO.sub.2 and Cs.sub.2 that can be incorporated into these glasses and crystalline ceramics far exceeds the limits set for the borosilicate high level waste glass.

  17. Cesium titanium silicate and method of making

    DOEpatents

    Balmer, M.L.

    1997-01-07

    The invention is the new material, a ternary compound of cesium, silica, and titania, together with a method of making the ternary compound, cesium titanium silicate pollucite. More specifically, the invention is Cs{sub 2}Ti{sub 2}Si{sub 4}O{sub 13} pollucite which is a new crystalline phase representing a novel class of Ti-containing zeolites. Compositions contain relatively high Cs{sub 2}O and TiO{sub 2} loadings and are durable glass and ceramic materials. The amount of TiO{sub 2} and Cs{sub 2} that can be incorporated into these glasses and crystalline ceramics far exceeds the limits set for the borosilicate high level waste glass. 10 figs.

  18. Thermal Ablation Modeling for Silicate Materials

    NASA Technical Reports Server (NTRS)

    Chen, Yih-Kanq

    2016-01-01

    A thermal ablation model for silicates is proposed. The model includes the mass losses through the balance between evaporation and condensation, and through the moving molten layer driven by surface shear force and pressure gradient. This model can be applied in ablation simulations of the meteoroid or glassy Thermal Protection Systems for spacecraft. Time-dependent axi-symmetric computations are performed by coupling the fluid dynamics code, Data-Parallel Line Relaxation program, with the material response code, Two-dimensional Implicit Thermal Ablation simulation program, to predict the mass lost rates and shape change. For model validation, the surface recession of fused amorphous quartz rod is computed, and the recession predictions reasonably agree with available data. The present parametric studies for two groups of meteoroid earth entry conditions indicate that the mass loss through moving molten layer is negligibly small for heat-flux conditions at around 1 MW/cm(exp. 2).

  19. A water-ethanol mixed-solution hydrothermal route to silicates nanowires

    SciTech Connect

    Wang Xun . E-mail: wangxun@mail.tsinghua.edu.cn; Zhuang Jing; Peng Qing; Li Yadong . E-mail: ydli@mail.tsinghua.edu.cn

    2005-07-15

    In this manuscript, series of silicates nanowires, such as calcium silicate, strontium silicate, barium silicate, zinc silicate and cadmium silicate, etc., have been successfully prepared from a water-ethanol mixed solution system through a hydrothermal synthetic way. The formation process of these silicates nanowires has been studied in detail. Due to their rich sources and possible novel properties from reduced dimensionalities, we believe that the synthesis of these silicates nanowires may bring some new opportunity in the solid state chemistry and nanoscience and technology fields, etc.

  20. Interstellar Silicate Dust in the z = 0.89 Absorber toward PKS 1830-211: Crystalline Silicates at High Redshift?

    NASA Astrophysics Data System (ADS)

    Aller, Monique C.; Kulkarni, Varsha P.; York, Donald G.; Vladilo, Giovanni; Welty, Daniel E.; Som, Debopam

    2012-03-01

    We present evidence of a >10σ detection of the 10 μm silicate dust absorption feature in the spectrum of the gravitationally lensed quasar PKS 1830-211, produced by a foreground absorption system at redshift 0.886. We have examined more than 100 optical depth templates, derived from both observations of Galactic and extragalactic sources and laboratory measurements, in order to constrain the chemical structure of the silicate dust. We find that the best fit to the observed absorption profile is produced by laboratory crystalline olivine, with a corresponding peak optical depth of τ10 = 0.27 ± 0.05. The fit is slightly improved upon by including small contributions from additional materials, such as silica, enstatite, or serpentine, which suggests that the dust composition may consist of a blend of crystalline silicates. Combining templates for amorphous and crystalline silicates, we find that the fraction of crystalline silicates needs to be at least 95%. Given the rarity of extragalactic sources with such a high degree of silicate crystallinity, we also explore the possibility that the observed spectral features are produced by amorphous silicates in combination with other molecular or atomic transitions, or by foreground source contamination. While we cannot rule out these latter possibilities, they lead to much poorer profile fits than for the crystalline olivine templates. If the presence of crystalline interstellar silicates in this distant galaxy is real, it would be highly unusual, given that the Milky Way interstellar matter contains essentially only amorphous silicates. It is possible that the z = 0.886 absorber toward PKS 1830-211, well known for its high molecular content, has a unique star-forming environment that enables crystalline silicates to form and prevail.

  1. INTERSTELLAR SILICATE DUST IN THE z = 0.89 ABSORBER TOWARD PKS 1830-211: CRYSTALLINE SILICATES AT HIGH REDSHIFT?

    SciTech Connect

    Aller, Monique C.; Kulkarni, Varsha P.; Som, Debopam; York, Donald G.; Welty, Daniel E.; Vladilo, Giovanni

    2012-03-20

    We present evidence of a >10{sigma} detection of the 10 {mu}m silicate dust absorption feature in the spectrum of the gravitationally lensed quasar PKS 1830-211, produced by a foreground absorption system at redshift 0.886. We have examined more than 100 optical depth templates, derived from both observations of Galactic and extragalactic sources and laboratory measurements, in order to constrain the chemical structure of the silicate dust. We find that the best fit to the observed absorption profile is produced by laboratory crystalline olivine, with a corresponding peak optical depth of {tau}{sub 10} = 0.27 {+-} 0.05. The fit is slightly improved upon by including small contributions from additional materials, such as silica, enstatite, or serpentine, which suggests that the dust composition may consist of a blend of crystalline silicates. Combining templates for amorphous and crystalline silicates, we find that the fraction of crystalline silicates needs to be at least 95%. Given the rarity of extragalactic sources with such a high degree of silicate crystallinity, we also explore the possibility that the observed spectral features are produced by amorphous silicates in combination with other molecular or atomic transitions, or by foreground source contamination. While we cannot rule out these latter possibilities, they lead to much poorer profile fits than for the crystalline olivine templates. If the presence of crystalline interstellar silicates in this distant galaxy is real, it would be highly unusual, given that the Milky Way interstellar matter contains essentially only amorphous silicates. It is possible that the z = 0.886 absorber toward PKS 1830-211, well known for its high molecular content, has a unique star-forming environment that enables crystalline silicates to form and prevail.

  2. Visible absorption spectra of the 4f electron transitions of neodymium, praseodymium, holmium and erbium complexes with fleroxacin and their analytical application.

    PubMed

    Wang, Naixing; Jiang, Wei; Xu, Xiuqin; Si, Zhikun; Bai, Haitao; Tian, Cong

    2002-05-01

    The absorption spectra of the 4f electron transitions of neodymium, praseodymium, holmium and erbium complexes with fleroxacin in the presence of cetylpyridinium chloride were studied by normal and derivative spectrophotometry. Their molar absorptivity at the maximum absorption bands are about 5.3 (at 571 nm) times greater for neodymium, 2.8 (at 483 nm) times greater for praseodymium, 12.6 (at 448.5 nm) times greater for holmium and 9.7 (at 519 nm) times greater for erbium than those in the absence of complexing agents. The second-derivative spectrum is used both to eliminate the interference from other rare earths and to improve the sensitivity. Beer's law is obeyed from 3.0 - 70 microg ml(-1) for neodymium and holmium, from 6.0 - 70 microg ml(-1) for erbium, and from 12.0 - 70 microg ml(-1) for praseodymium. The relative standard deviations are 1.9% and 1.5% for 7.5 microg ml(-1) of neodymium and holmium, and 2.1% and 1.6% for 15.0 microg ml(-1) of praseodymium and erbium, respectively. Their detection limits (signal-to-noise ratio = 2) are 3.2 microg ml(-1), 1.3 microg ml(-1), (1.1) microg ml(-1) and 2.5 microg ml(-1) for praseodymium, neodymium, holmium and erbium, respectively. A new system for the simultaneous determinations of the praseodymium, neodymium, holmium and erbium in rare earth mixtures with good accuracy and selectivity is proposed.

  3. Layer silicates in a chondritic porous interplanetary dust particle

    NASA Technical Reports Server (NTRS)

    Rietmeijer, F. J. M.; Mackinnon, I. D. R.

    1985-01-01

    Analytical electron microscopy on individual grains from a portion of a chondritic porous interplanetary dust particle (aggregate W7029C1 from the NASA Johnson Space Center Cosmic Dust Collection) shows that layer silicates compose 50 percent of the silicate fraction examined. These layer silicates can be classified into two distinct crystallochemical groups: (1) fine-grained, polycrystalline smectite minerals; and (2) well-ordered, single crystals of kaolinite and Mg-poor talc. The layer silicates in this portion of sample W7029(asterisk)A are dissimilar to those described in other chondritic porous aggregates. The predominant layer silicate assemblage in W7029(asterisk)A indicates that heating of the aggregate during atmospheric entry was brief and probably to a temperature less than 300 C. Comparison with terrestrial phyllosilicate occurrences suggests that some layer silicates in aggregate W7029(asterisk)A may have been formed by alteratiton from preexisting silicate minerals at low temperatures (less than 25 C) after aggregate formation.

  4. Characterization of chitin-metal silicates as binding superdisintegrants.

    PubMed

    Rashid, Iyad; Daraghmeh, Nidal; Al-Remawi, Mayyas; Leharne, Stephen A; Chowdhry, Babur Z; Badwan, Adnan

    2009-12-01

    When chitin is used in pharmaceutical formulations, processing of chitin with metal silicates is advantageous, from both an industrial and pharmaceutical perspective, compared to processing using silicon dioxide. Unlike the use of acidic and basic reagents for the industrial preparation of chitin-silica particles, coprecipitation of metal silicates is dependent upon a simple replacement reaction between sodium silicate and metal chlorides. When coprecipitated onto chitin particles, aluminum, magnesium, or calcium silicates result in nonhygroscopic, highly compactable/disintegrable compacts. Disintegration and hardness parameters for coprocessed chitin compacts were investigated and found to be independent of the particle size. Capillary action appears to be the major contributor to both water uptake and the driving force for disintegration of compacts. The good compaction and compression properties shown by the chitin-metal silicates were found to be strongly dependent upon the type of metal silicate coprecipitated onto chitin. In addition, the inherent binding and disintegration abilities of chitin-metal silicates are useful in pharmaceutical applications when poorly compressible and/or highly nonpolar drugs need to be formulated.

  5. Layer silicates in a chondritic porous interplanetary dust particle

    NASA Astrophysics Data System (ADS)

    Rietmeijer, F. J. M.; MacKinnon, I. D. R.

    1985-11-01

    Analytical electron microscopy on individual grains from a portion of a chondritic porous interplanetary dust particle (aggregate W7029C1 from the NASA Johnson Space Center Cosmic Dust Collection) shows that layer silicates compose 50 percent of the silicate fraction examined. These layer silicates can be classified into two distinct crystallochemical groups: (1) fine-grained, polycrystalline smectite minerals; and (2) well-ordered, single crystals of kaolinite and Mg-poor talc. The layer silicates in this portion of sample W7029(asterisk)A are dissimilar to those described in other chondritic porous aggregates. The predominant layer silicate assemblage in W7029(asterisk)A indicates that heating of the aggregate during atmospheric entry was brief and probably to a temperature less than 300 C. Comparison with terrestrial phyllosilicate occurrences suggests that some layer silicates in aggregate W7029(asterisk)A may have been formed by alteratiton from preexisting silicate minerals at low temperatures (less than 25 C) after aggregate formation.

  6. Reagentless and calibrationless silicate measurement in oceanic waters.

    PubMed

    Giraud, William; Lesven, Ludovic; Jońca, Justyna; Barus, Carole; Gourdal, Margaux; Thouron, Danièle; Garçon, Véronique; Comtat, Maurice

    2012-08-15

    Determination of silicate concentration in seawater without addition of liquid reagents was the key prerequisite for developing an autonomous in situ electrochemical silicate sensor (Lacombe et al., 2007) [11]. The present challenge is to address the issue of calibrationless determination. To achieve such an objective, we chose chronoamperometry performed successively on planar microelectrode (ME) and ultramicroelectrode (UME) among the various possibilities. This analytical method allows estimating simultaneously the diffusion coefficient and the concentration of the studied species. Results obtained with ferrocyanide are in excellent agreement with values of the imposed concentration and diffusion coefficient found in the literature. For the silicate reagentless method, successive chronoamperometric measurements have been performed using a pair of gold disk electrodes for both UME and ME. Our calibrationless method was tested with different concentrations of silicate in artificial seawater from 55 to 140×10(-6) mol L(-1). The average value obtained for the diffusion coefficient of the silicomolybdic complex is 2.2±0.4×10(-6) cm(2) s(-1), consistent with diffusion coefficient values of molecules in liquid media. Good results were observed when comparing known concentration of silicate with experimentally derived ones. Further work is underway to explore silicate determination within the lower range of oceanic silicate concentration, down to 0.1×10(-6) mol L(-1).

  7. Comparison of responses of tattoos to picosecond and nanosecond Q-switched neodymium: YAG lasers.

    PubMed

    Ross, V; Naseef, G; Lin, G; Kelly, M; Michaud, N; Flotte, T J; Raythen, J; Anderson, R R

    1998-02-01

    To test the hypothesis that picosecond laser pulses are more effective than nanosecond domain pulses in clearing of tattoos. Intratattoo comparison trial of 2 laser treatment modalities. A large interdisciplinary biomedical laser laboratory on the campus of a tertiary medical center. Consecutive patients with black tattoos were enrolled; all 16 patients completed the study. We treated designated parts of the same tattoo with 35-picosecond and 10-nanosecond pulses from 2 neodymium:YAG lasers. Patients received a total of 4 treatments at 4-week intervals. All laser pulse parameters were held constant except pulse duration. Radiation exposure was 0.65 J/cm2 at the skin surface. Biopsies were performed for routine microscopic and electron microscopic analysis at the initial treatment session and 4 weeks after the final treatment in 8 consenting patients. Also, ink samples were irradiated in vitro. In vivo, on the completion of treatment, a panel of dermatologists not associated with the study (and blinded to the treatment type) evaluated photographs to assess tattoo lightening. Formalin-fixed specimens were examined for qualitative epidermal and dermal changes as well as depth of pigment alteration. Electron micrographs were examined for particle electron density and size changes (in vivo and in vitro). The gross in vitro optical density changes were measured. In 12 of 16 tattoos, there was significant lightening in the picosecond-treated areas compared with those treated with nanosecond pulses. Mean depth of pigment alteration was greater for picosecond pulses, but the difference was not significant. In vivo biopsy specimens showed similar electron-lucent changes for both pulse durations. In vitro results were similar for both pulse durations, showing increases in particle sizes and decreased electron density as well as gross ink lightening. Picosecond pulses are more efficient than nanosecond pulses in clearing black tattoos. Black tattoos clear principally by laser

  8. Neodymium associated with foraminiferal carbonate as a recorder of seawater isotopic signatures

    NASA Astrophysics Data System (ADS)

    Tachikawa, Kazuyo; Piotrowski, Alexander M.; Bayon, Germain

    2014-03-01

    Neodymium isotopic ratios in marine environments have been used as a tracer of water masses and exchange processes between dissolved and particulate phases. The interest in this tracer has been growing with improvement of our knowledge on its chemical behaviour in the modern ocean and the identification of sedimentary phases that preserve past seawater ɛNd values. In the last few decades the Nd isotopic composition measured on Fe-Mn crusts, sediment leachates, bulk carbonate fraction, corals and fish teeth have been increasingly interpreted in the context of understanding the role of the ocean in paleoclimate changes. In particular, calcareous foraminiferal tests (shells) have acquired increasing attention as an archive of seawater Nd isotopic signatures, because it allows continuous high-resolution records to be measured and directly compared to other proxies including stable isotopes and trace metals. The main challenge of interpreting the Nd isotopic composition of foraminifera is determining the origin of the Nd preserved within them. In this review, we present an overview of methodological progress including that of bulk foraminifera and microanalyses within foraminiferal tests, as well as geochemical meaning of extracted Nd concentrations and isotopic compositions. The growing body of evidence suggests that Nd isotopic signatures of sedimentary planktonic foraminifera correspond to bottom water values rather than surface water ones. The Nd-rich phases associated with sedimentary foraminifera are adhesive nano-scale particles of Mn and Fe oxides and hydroxides, and Mn-rich carbonates formed within layers of foraminiferal calcite. Mechanical cleaning to remove clay minerals is likely to be sufficient in most cases to reconstruct past bottom water circulations. Unresolved issues include the potential influence of pore water Nd on ɛNd values extracted from sedimentary foraminiferal tests under different sedimentalogical and oceanographic conditions.

  9. Development of an empirical kinetic model for sonocatalytic process using neodymium doped zinc oxide nanoparticles.

    PubMed

    Khataee, Alireza; Vahid, Behrouz; Saadi, Shabnam; Joo, Sang Woo

    2016-03-01

    The degradation of Acid Blue 92 (AB92) solution was investigated using a sonocatalytic process with pure and neodymium (Nd)-doped ZnO nanoparticles. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The 1% Nd-doped ZnO nanoparticles demonstrated the highest sonocatalytic activity for the treatment of AB92 (10 mg/L) with a degradation efficiency (DE%) of 86.20% compared to pure ZnO (62.92%) and sonication (45.73%) after 150 min. The results reveal that the sonocatalytic degradation followed pseudo-first order kinetics. An empirical kinetic model was developed using nonlinear regression analysis to estimate the pseudo-first-order rate constant (kapp) as a function of the operational parameters, including the initial dye concentration (5-25 mg/L), doped-catalyst dosage (0.25-1 g/L), ultrasonic power (150-400 W), and dopant content (1-6% mol). The results from the kinetic model were consistent with the experimental results (R(2)=0.990). Moreover, DE% increases with addition of potassium periodate, peroxydisulfate, and hydrogen peroxide as radical enhancers by generating more free radicals. However, the addition of chloride, carbonate, sulfate, and t-butanol as radical scavengers declines DE%. Suitable reusability of the doped sonocatalyst was proven for several consecutive runs. Some of the produced intermediates were also detected by GC-MS analysis. The phytotoxicity test using Lemna minor (L. minor) plant confirmed the considerable toxicity removal of the AB92 solution after treatment process.

  10. Optical and spectroscopic properties of neodymium doped cadmium-sodium borate glasses

    NASA Astrophysics Data System (ADS)

    Mohan, Shaweta; Thind, Kulwant Singh

    2017-10-01

    Neodymium doped cadmium sodium borate glasses having composition xCdO-(40-x) Na2CO3-59.5H3BO3-0.5Nd2O3; x = 10, 20 and 30 mol% were prepared by conventional melt-quenching technique. X-ray diffraction studies confirmed the amorphous nature of the prepared glasses. Conventional methods were used to determine the physical properties such as density, molar volume, refractive index, and rare earth ion concentration. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Ω2, Ω4 and Ω6. The calculated intensity parameters were further used to predict the radiative transition probability (A), radiative lifetime (τR) and branching ratio (βR) for the various fluorescent levels of Nd3+ ion in the prepared glass series. The effect of the compositional changes on the spectroscopic characteristics of Nd3+ ions have been studied and reported. The value of Ω2 is found to decrease with the decrease in the sodium content and the corresponding increase in the cadmium content. This can be ascribed to the changes in the asymmetry of the ligand field at the rare earth ion site and the change in rare earth oxygen (RE-O) covalency. Florescence spectra has been used to determine the peak wavelength (λp), effective line widths (Δλeff) and stimulated emission cross-section (σp) for the 4F3/2 → 4I9/2,4I11/2,4I13/2 transitions of the Nd3+ ion. The reasonably higher values of branching ratios and stimulated emission cross-section for the prepared glasses points towards the efficacy of these glasses as laser host materials. However, the glass with more sodium content is found to show better lasing properties.

  11. Electrochemical properties of dual phase neodymium-doped ceria alkali carbonate composite electrolytes in intermediate temperature

    NASA Astrophysics Data System (ADS)

    Kim, Ji-Tae; Lee, Tae-Hee; Park, Ka-Young; Seo, Yongho; Kim, Ki Buem; Song, Sun-Ju; Park, Byoungnam; Park, Jun-Young

    2015-02-01

    Composite electrolyte materials composed of neodymium-doped ceria (Nd0.2Ce0.8O1.9; NDC) and (Li-0.5Na)2CO3 are investigated to understand the unique behaviors of their multi-ionic conduction. In the intermediate temperature, the NDC-based carbonate composite electrolytes exhibit a much higher conductivity compared to pure NDC. It has been claimed that the oxide ions are transported in the doped-ceria phase via oxygen vacancies and the protons are conducted through the second carbonate phase, thereby resulting in an enhanced ionic conductivity. However, it has not been experimentally demonstrated if the proton conduction within the carbonate phase aided in improving the conductivity of oxygen ions in the composite system. Hence, the primary objective of this work is to cultivate a deeper insight into the conduction property of these composites as an attempt to clarify the ionic transport phenomenon responsible for enhanced conductivity. Electrical conductivities of NDC and NDC/carbonate materials are investigated as a function of oxygen partial pressure and vapor pressure of water to understand transport properties of composite electrolytes. The ionic and electronic transference numbers of composite electrolytes are measured by the oxygen- and hydrogen-concentration cells containing water. The dominant charge carriers are identified quantitatively through the analysis of the partial conductivity of proton, oxygen ions, and electrons (holes). Understanding the transport properties and transference numbers of composite electrolytes can contribute to the development of commercial solid oxide fuel cells, which can be done by reducing the operating temperature using a highly ionic conductive NDC/carbonate composite electrolyte at the intermediate temperature.

  12. A spectrophotometric study of neodymium(III) complexation in chloride solutions

    NASA Astrophysics Data System (ADS)

    Migdisov, Art A.; Williams-Jones, A. E.

    2002-12-01

    The formation constants of neodymium complexes in chloride solutions have been determined spectrophotometrically at temperatures of 25 to 250°C and a pressure of 50 bars. The simple ion, Nd 3+, is dominant at 25°C, whereas NdCl 2+ and NdCl 2+ are the dominant species at elevated temperatures. Equilibrium constants were calculated for the following reactions: Nd 3+ + Cl - = NdCl 2+ β 1, Nd 3+ + 2 · Cl - = NdCl +2 β 2. The values of β 1 were found to be identical within experimental error to the values reported by Gammons et al. (1996) but substantially different from those proposed by Stepanchikova and Kolonin (1999). The values of β 2 obtained in this study agree relatively well with those of Gammons et al. (1996); differences are greatest at intermediate temperature and reach a maximum of one half an order of magnitude at 200°C. Theoretical estimates of β 1 and β 2 by Haas et al. (1995) using the revised Helgeson-Kirkham-Flowers (HKF) equation of state predict lower stability of NdCl 2+ and NdCl 2+ at temperatures above 150°C than determined in this study. A new fit to the HKF equation of state is therefore proposed, which yields values for β 1 and β 2 similar to those obtained experimentally. Using the formation constants reported in this study, we predict that typical seafloor hydrothermal vent fluids will contain a maximum concentration of Nd of ˜2 ppb. This value is several orders of magnitude lower than would be required to explain the levels of Nd mobility commonly reported for seafloor hydrothermal systems and suggests that other ligands may be more important than Cl in transporting rare earth elements in the Earth's crust.

  13. A spectrophotometric study of neodymium(III) complexation in sulfate solutions at elevated temperatures

    NASA Astrophysics Data System (ADS)

    Migdisov, Art. A.; Reukov, V. V.; Williams-Jones, A. E.

    2006-02-01

    The formation constants of neodymium complexes in sulfate solutions have been determined spectrophotometrically at temperatures of 30-250 °C and a pressure of 100 bars. The dominant species in the solution are NdSO 4+ and Nd(SO 4) 2-, with the latter complex being more important at higher temperature. Equilibrium constants were calculated for the following reactions: Nd+SO4=NdSO4,β1; Nd+2·SO4=Nd(SO4)2,β2; NdSO4+SO4=Nd(SO4)2,Ks. The values of β1 and β2, were determined for 30 and 100 °C, whereas for higher temperatures it was only possible to determine the stepwise formation constant Ks. The values of the formation constants obtained in this study for 30 and 100 °C are in excellent agreement with those predicted theoretically by Wood [Wood, S.A., 1990b. The aqueous geochemistry of the rare-earth elements and yttrium. 2. Theoretical predictions of speciation in hydrothermal solutions to 350 °C at saturation water vapor pressure. Chem. Geol.88 (1-2), 99-125] and Haas et al. [Haas, J.R., Shock, E.L., Sassani, D.C., 1995. Rare earth elements in hydrothermal sysytems: estimates of standard partial molal thermodynamic properties of aqueous complexes of the rare earth elements at high pressures and temperatures. Geochim. Cosmochim. Acta59 (21), 4329-4350], and those for the stepwise formation constant ( Ks) agree reasonably well with the predictions of Wood (1990b).

  14. Passive Q-switching of a diode-pumped neodymium:YAG laser

    SciTech Connect

    Morris, J.A.

    1991-01-01

    Compact diode-pumped neodymium:YAG lasers are becoming common commercial devices. Such lasers are often Q-switched to enhance peak power or to allow greater harmonic conversion efficiency. Active electrooptic or acoustooptic modulators are usually used to Q-switch YAG lasers. While these techniques work well, they do require expensive and bulky modulators and driving electronics. For some applications a simpler technique, such as passive Q-switching, could replace these active Q-switches. This thesis investigates the suitability of two color center materials as possible saturable absorbers for compact Nd:YAG lasers. The first material, lithium fluoride with F{sub 2}{sup {minus}} defects, has been used previously as a Q-switch for flashlamp-pumped Nd:YAG lasers. The second material, sodium chloride with F{sub 2}{sup +} defects, has not, to the author's knowledge, been used as a saturable absorber in a YAG laser. Lithium fluoride was found to be an excellent Q-switch material for a small diode-pumped YAG laser. The passively Q-switched pulses were comparable to the best results using active Q-switches. The LiF saturable absorber material is compact, inexpensive, and easy to prepare. The only discovered drawback to this material is the observation of a gradual bleaching of the saturable absorption with extended use at high peak powers. This thesis describes the properties and preparation of the LiF Q-switch material. The use of colored sodium chloride as a Q-switch material is also described. This material has the unique property that the amount of saturable loss in a particular crystal direction can be dynamically adjusted through the action of polarized light incident on the crystal.

  15. Optimal pulse durations for the treatment of leg telangiectasias with a neodymium YAG laser.

    PubMed

    Parlette, Eric C; Groff, William F; Kinshella, Matthew J; Domankevitz, Yacov; O'Neill, Jennifer; Ross, E Victor

    2006-02-01

    Leg veins can be effectively treated with lasers. However, the optimal pulse duration for small leg veins has not been established in human studies with a Nd:YAG laser. The purpose of this study was to investigate a range of pulse durations to determine an optimal pulse duration for clearance of leg veins. After mapping and photo documentation of the leg veins to be treated, a variable pulse duration Neodymium:Yttrium Aluminum Garnet (Nd:YAG) laser (3-100 milliseconds) was used in a single test site session. Pulse durations of 3, 20, 40, 60, 80, and 100 milliseconds were used. At the 3-week follow-up, the optimal pulse duration was defined as that pulse duration which resulted in the most complete clearance of vessels with the least side effects. Up to 20 vessels were then treated using the established "optimal" pulse duration. Final evaluation was at 16 weeks after the initial visit. Three blinded observers rated the percent of vessels completely cleared based on initial and final photographs. Eighteen patients completed the study. Fluence thresholds for immediate vessel changes varied depending on spot size and vessel diameter, with larger fluences required for smaller spot sizes and smaller vessels. Shorter pulse durations (< or =20 milliseconds) were associated with occasional spot sized purpura and spot sized post-inflammatory hyperpigmentation. Longer pulse durations (40-60 milliseconds) achieved superior vessel elimination with less post-inflammatory hyperpigmentation. With a single laser treatment, 71% of the treated vessels cleared. Compared to shorter pulses (<20 milliseconds), longer pulses may provide gentler heating of the vessel and a greater ratio of contraction to thrombosis. Copyright 2005 Wiley-Liss, Inc.

  16. Past Hydrological Variability in the Congo Basin inferred from Neodymium Isotopes

    NASA Astrophysics Data System (ADS)

    Bayon, G.

    2015-12-01

    Major events of vegetation changes and soil erosion occurred in Central Africa during the last few millennia, at a time when the first farmers settled in the rainforest. The palaeoclimatic context in which these environmental changes took place still remains poorly constrained. Improving our knowledge on the drivers of past hydrological variability in Central Africa is important to further evaluate the relative role of climate versus humans in shaping late Holocene African landscapes. In this study, we have used neodymium (Nd) isotopes in a marine sediment core to reconstruct the composition of the sediment load exported from the Congo Basin during the Holocene. Core KZR23 was recovered at 2200 m water depth from within the Congo submarine canyon and is characterized by high sedimentation rates (about 2m/kyr), thereby allowing reconstruction of past river sediment discharge at an unprecedented high temporal resolution. A suite of river particulate samples collected from the main tributaries within the Congo watershed was analyzed in order to tag each major sub-basin with the characteristic geochemical and Nd isotopic signatures of its source region. In parallel, an annual series of suspended particles sampled on a monthly basis at the Congo River ORE-HYBAM station (Brazzaville) was also analyzed to characterize the seasonality of sediment provenance in relation with present hydrological cycle. Using Nd isotopes as tracers for sediment provenance together and other proxy data for past erosion, vegetation and rainfall patterns (i.e. bulk sediment radiocarbon data, pollens, biomarkers, compound-specific isotope analyses), we will provide a more comprehensive picture of past hydrological variability in the Congo Basin for the Holocene period.

  17. Cataracts induced by neodymium-yttrium-aluminium-garnet laser lysis of vitreous floaters.

    PubMed

    Koo, Ellen H; Haddock, Luis J; Bhardwaj, Namita; Fortun, Jorge A

    2017-06-01

    Neodymium-yttrium-aluminium-garnet (Nd:YAG) laser vitreolysis has been proposed as a treatment modality for symptomatic vitreous floaters. The purpose of this paper is to report two cases of cataracts associated with posterior capsular compromise, induced by Nd:YAG laser vitreolysis for symptomatic vitreous floaters. Case series. Two patients who underwent ND:YAG laser vitreolysis for symptomatic floaters, presented with decline in visual acuity in the treated eye after the laser procedure. At the slit-lamp biomicroscope, each patient was found to have a posterior subcapsular cataract in the treated eye, with obvious loss of integrity of the posterior capsule. These two patients underwent cataract extraction by the same surgeon via phacoemulsification. Both eyes were found to have a defect in the posterior capsule intraoperatively. In both cases, a three-piece acrylic intraocular lens implant was placed in the sulcus, achieving optic capture. The best-corrected visual acuity (BCVA) was 20/20 in both patients, at 1 month following the surgery. At 2 months, one patient had a BCVA of 20/15. The second patient maintained a BCVA of 20/20 at 3 months. Secondary cataract formation accompanied by loss of integrity of the posterior capsule is a potential complication of Nd:YAG laser vitreolysis for symptomatic floaters. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  18. Neodymium isotopic composition of intermediate and deep waters in the glacial southwest Pacific

    NASA Astrophysics Data System (ADS)

    Noble, Taryn L.; Piotrowski, Alexander M.; McCave, I. Nick

    2013-12-01

    Neodymium (Nd) isotopes, tracers of deep water mass source and mixing, were measured on sedimentary planktic foraminifera with authigenic coatings from a depth-transect of cores (1400-4800 m) from Chatham Rise in the southwest Pacific, over the past 30 ka. We observe deglacial variations in the Nd isotopic composition, which showed an average glacial composition of ɛNd=-5.0 (1σ; ±0.3n=4) for cores sites below 3200 mbsl. No significant deglacial variation was observed in the Nd isotopic composition of intermediate depth waters (1400 mbsl), in contrast with benthic foraminifera δC13 data. The deglacial ɛNd shift of CDW in the southwest Pacific is consistent with changes observed in the deep South Atlantic and Equatorial Indian Ocean, but ɛNd values are offset by ˜1ɛNd-unit to more radiogenic values throughout the deglacial records, likely due to admixture of a Nd isotope signal which was modified in the Southern Ocean or Pacific, perhaps by boundary exchange. However, this modification did not overprint the deglacial Nd isotope change. The consistent deglacial evolution of ɛNd in the South Atlantic, Equatorial Indian and southwest Pacific CDW, is evidence for the connection of CDW during the glacial, and propagation of diminished North Atlantic Deep Water export to the glacial Southern Ocean. In contrast, spatial heterogeneities in the benthic foraminifera δC13 of CDW have been observed in the Atlantic, Indian and Pacific basins of the deep glacial Southern Ocean. The Nd isotope data implies a well-connected deep Southern Ocean, which transported waters from the Atlantic to the Indian and Pacific oceans, during the glacial. This suggests that basin-scale variability in the glacial δC13 composition of CDW was unrelated to circulation changes.

  19. How Well Do Neodymium Isotopes Trace AMOC Mixing? A Test in the Southwest Atlantic

    NASA Astrophysics Data System (ADS)

    Wu, Y.; Goldstein, S. L.; Pena, L.; Hartman, A. E.; Rijkenberg, M. J. A.; De Baar, H. J. W.

    2014-12-01

    Neodymium (Nd) isotope ratios are used to trace past AMOC circulation, based on observations that seawater Nd isotope ratios effectively "fingerprint" water masses, and that over long water mass transport distances in deep seawater they reflect values expected from water mass mixing. Over the past several years, studies have increasingly focused on the potential of external addition of Nd along water mass transport paths (for example through "boundary exchange" with particulates or addition from groundwaters), thus challenging the idea that Nd isotopes behave "quasi-conservatively" in the oceans. The SW Atlantic, with the major water masses involved in the AMOC (southward flowing NADW, northward flowing AAIW and AABW), is arguably the best place on Earth to evaluate how well Nd isotopes trace water mass mixing, in order to clarify its value for following the AMOC through time. We will report Nd isotope ratios of seawater collected on the SW Atlantic meridional transect of the NIOZ West Atlantic GEOTRACES Cruise Leg 3 (RRS James Cook 057), which sampled seawater profiles and the sediment surface at 18 stations between 0-50°S. Most stations are sampled in the open ocean, providing a test of whether Nd isotopes show quasi-conservative mixing systematics away from continental margins. The cruise section also provides several opportunities to test the potential effects of external Nd input. For example, it transects the continental shelf in the far south, the Rio Grande Rise, volcanic seamounts, and the major geological age boundaries of South America. It also crosses the major Southern Hemisphere wind zones, allowing us to test the impacts of aeolian input, and inputs from major rivers (Parana-Paraguay, Sao Francisco, Amazon). All of these features have the potential to modify the seawater Nd isotope ratios, allowing us to determine if they add significant external Nd.

  20. Effect of neodymium substitution on structural and ferroelectric properties of BNT ceramics

    SciTech Connect

    Pal, Vijayeta; Dwivedi, R.K.; Thakur, O.P.

    2014-03-01

    Graphical abstract: - Highlights: • First time, we synthesized (Bi{sub 1−x}Nd{sub x}){sub 0.5}Na{sub 0.5}TiO{sub 3} system by semi wet technique. • Grain size reduced with doping and Nd acts as an inhibitor in the grain growth. • Specimen with x = 0.02 exhibits excellent ferroelectric properties at RT. • P–E loops show the co-existence of polar and non polar regions around ‘T{sub d}’. - Abstract: Polycrystalline specimens of (Bi{sub 1−x}Nd{sub x}){sub 0.5}Na{sub 0.5}TiO{sub 3} (BNNT) ceramic system with compositions x ≤ 0.04 were synthesized by semi-wet technique using ethylene glycol precursor. Structural and electrical properties were investigated in detail to observe the effect of neodymium (Nd) substitution in BNT system. XRD patterns for all the specimens showed single phase formation with rhombohedral structure. Field emission scanning electron micrographs (FE-SEM) revealed that the grain growth was inhibited significantly with Nd content. The temperature dependence behaviour of dielectric constant revealed that the depolarisation temperature ‘T{sub d}’ decreases whereas temperature of maximum dielectric constant ‘T{sub m}’ increases with Nd concentration. The piezoelectric charge coefficient (d{sub 33}) showed maxima at x = 0.02 and well defined ferroelectric behaviour was observed for all the samples.

  1. High resolution neodymium characterization along the Mediterranean Sea margins: implications for ɛNd modeling.

    NASA Astrophysics Data System (ADS)

    Ayache, Mohamed; Dutay, Jean-claude; Arsouze, Thomas; Jeandel, Catherine; Revillon, Sidonie

    2016-04-01

    An extensive compilation of published neodymium (Nd) concentrations and isotopic compositions (ɛNd) was realized in order to establish a new database and a map (using a high resolution geological map of the area) of the distribution of these parameters for all the Mediterranean margins. Data were extracted from different kinds of samples: river solid discharge deposited on the shelf, sedimentary material collected on the margin or geological material outcropping above or close to a margin. Additional analyses of surface sediments were done, in order to improve this dataset in key areas (e.g Sicilian strait). The Mediterranean margin Nd isotopic signatures vary from non-radiogenic values around the Gulf of Lions, (ɛNd values -11) to radiogenic values around the Aegean and the Levantine sub-basins up to +6. Using a high resolution regional oceanic model (1/12° of horizontal resolution), ɛNd distribution was simulated for the first time in the Mediterranean Sea. The high resolution of the model provides the opportunity to study in more details the processes governing the Nd isotope distribution in the marine environment. This work highlights that a significant interannual variability of ɛNd distribution in seawater could occur. In particular, important hydrological events such as the Eastern Mediterranean Transient (EMT), associated with deep water formed in the Aegean sub-basin, could induce a shift in Nd IC at intermediate depths that could be noticeable in the Western part of the basin. This highlights that the temporal and geographical variations of ɛNd could represent an interesting insight of Nd as a quasi-conservative tracer of water masses in the Mediterranean Sea, in particular in the context of paleo-oceanographic applications, i.e. to explore if EMT-type signatures occurred in the past (Roether et al., 2014, Gacic et al., 2011).

  2. Cerium(III) and neodymium(III) complexes as scavengers of X/XO-derived superoxide radical.

    PubMed

    Kostova, Irena; Traykova, Maria

    2006-09-01

    The cerium (III) and neodymium (III) complexes with 3,3'-benzylidenebis[4-hydroxycoumarin] were synthesized and characterized by different analytical and spectral methods. The synthesis of these complexes is taken into consideration with cytotoxic screening and study of their antioxidant effect. Their cytotoxicity toward cancerous cell cultures correlated with the weakness of the coordinative bond between the cation and organic ligand and with the capability to scavenge superoxide radicals as well. On the basis of the data reported by us earlier and our new results, it was proposed that cerium (III) complex with 3,3'-benzylidenebis[4-hydroxycoumarin] might induce intracellular acidification along with control over the extracellular oxidative stress.

  3. Acute effects of anti-inflammatory drugs on neodymium:yttrium aluminum garnet laser-induced uveitis in dogs.

    PubMed

    Millichamp, N J; Dziezyc, J; Rohde, B H; Chiou, G C; Smith, W B

    1991-08-01

    Dogs were treated with flunixin meglumine, a cyclooxygenase inhibitor; L-651,896, a 5-lipoxygenase inhibitor; and matrine, a herbal anti-inflammatory drug. Acute inflammation was induced in the eyes by disruption of the anterior lens capsule, using a neodymium:yttrium aluminum garnet laser. Intraocular pressure, pupil diameter, and eicosanoid production in the aqueous humor were measured. Statistically significant effects were seen in the eyes of flunixin meglumine-treated dogs where mydriasis was maintained and aqueous prostaglandin E2 concentration was reduced.

  4. Morphologic and histologic changes in canine temporomandibular joint tissues following arthroscopic guided neodymium:YAG laser exposure

    SciTech Connect

    Bradrick, J.P.; Eckhauser, M.L.; Indresano, A.T. )

    1989-11-01

    A neodymium:yttrium aluminum garnet (Nd:YAG) laser beam was introduced by a quartz fiber passed arthroscopically into the superior joint space of the temporomandibular joints (TMJ) of five mongrel dogs, with one joint serving as a control without laser wounds. Immediate postoperative death and examination of the disc grossly and histologically revealed different patterns for contact and noncontact burn wounds. The wounds exhibited signs of thermal coagulation necrosis similar to those reported in other tissues. The potential implications of the adaptation of the Nd:YAG laser to TMJ arthroscopic surgery are discussed.

  5. Clinical efficacy of the dual-pulsed Q-switched neodymium:yttrium-aluminum-garnet laser: Comparison with conservative mode.

    PubMed

    Kim, Byung Wook; Lee, Mi Hye; Chang, Sung Eun; Yun, Woo Jin; Won, Chong Hyun; Lee, Mi Woo; Choi, Jee Ho; Moon, Kee Chan

    2013-12-01

    The quality (Q)-switched neodymium:yttrium-aluminum-garnet (Nd:YAG) laser is one of the first non-ablative lasers to be used for facial resurfacing and photorejuvenation. Recently, the method of low-fluence Q-switched Nd:YAG lasers known as 'laser toning' has been used for non-ablative skin rejuvenation and for the treatment of melasma in Asian countries. We report our experience of using a novel Q-switched Nd:YAG laser that was operated as a dual pulse at half fluence and 140-μs intervals compared with conservative mode laser.

  6. Pupil block glaucoma after neodymium:YAG capsulotomy in a patient with a partially subluxated posterior chamber intraocular lens.

    PubMed

    Kersey, James P; McMullan, Tristan F W; Broadway, David C

    2005-07-01

    A 73-year-old-woman presented following neodymium:YAG capsulotomy for posterior capsular opacification with acute glaucoma. Previous cataract surgery had left her with a subluxated lens. Cornea edema obscured detail of the anterior chamber, but the edge of the lens could be seen clearly within the pupillary space. This produced a diagnostic dilemma because no obvious cause for pupil block could be seen. She failed to respond to medical therapy and had a laser iridotomy, following which her symptoms resolved. We believe this case demonstrates the importance of a laser iridotomy to exclude pupil block glaucoma when adequate visualization of the pupillary space is obscured.

  7. Twenty-Eight-Day Repeated Inhalation Toxicity Study of Nano-Sized Neodymium Oxide in Male Sprague-Dawley Rats.

    PubMed

    Kim, Yong-Soon; Lim, Cheol-Hong; Shin, Seo-Ho; Kim, Jong-Choon

    2017-07-01

    Neodymium is a future-oriented material due to its unique properties, and its use is increasing in various industrial fields worldwide. However, the toxicity caused by repeated exposure to this metal has not been studied in detail thus far. The present study was carried out to investigate the potential inhalation toxicity of nano-sized neodymium oxide (Nd2O3) following a 28-day repeated inhalation exposure in male Sprague-Dawley rats. Male rats were exposed to nano-sized Nd2O3-containing aerosols via a nose-only inhalation system at doses of 0 mg/m(3), 0.5 mg/m(3), 2.5 mg/m(3), and 10 mg/m(3) for 6 hr/day, 5 days/week over a 28-day period, followed by a 28-day recovery period. During the experimental period, clinical signs, body weight, hematologic parameters, serum biochemical parameters, necropsy findings, organ weight, and histopathological findings were examined; neodymium distribution in the major organs and blood, bronchoalveolar lavage fluid (BALF), and oxidative stress in lung tissues were analyzed. Most of the neodymium was found to be deposited in lung tissues, showing a dose-dependent relationship. Infiltration of inflammatory cells and pulmonary alveolar proteinosis (PAP) were the main observations of lung histopathology. Infiltration of inflammatory cells was observed in the 2.5 mg/m(3) and higher dose treatment groups. PAP was observed in all treatment groups accompanied by an increase in lung weight, but was observed to a lesser extent in the 0.5 mg/m(3) treatment group. In BALF analysis, total cell counts, including macrophages and neutrophils, lactate dehydrogenase, albumin, interleukin-6, and tumor necrosis factor-alpha, increased significantly in all treatment groups. After a 4-week recovery period, these changes were generally reversed in the 0.5 mg/m(3) group, but were exacerbated in the 10 mg/m(3) group. The lowest-observed-adverse-effect concentration of nano-sized Nd2O3 was determined to be 0.5 mg/m(3), and the target organ was determined to

  8. Twenty-Eight-Day Repeated Inhalation Toxicity Study of Nano-Sized Neodymium Oxide in Male Sprague-Dawley Rats

    PubMed Central

    Kim, Yong-Soon; Lim, Cheol-Hong; Shin, Seo-Ho; Kim, Jong-Choon

    2017-01-01

    Neodymium is a future-oriented material due to its unique properties, and its use is increasing in various industrial fields worldwide. However, the toxicity caused by repeated exposure to this metal has not been studied in detail thus far. The present study was carried out to investigate the potential inhalation toxicity of nano-sized neodymium oxide (Nd2O3) following a 28-day repeated inhalation exposure in male Sprague-Dawley rats. Male rats were exposed to nano-sized Nd2O3-containing aerosols via a nose-only inhalation system at doses of 0 mg/m3, 0.5 mg/m3, 2.5 mg/m3, and 10 mg/m3 for 6 hr/day, 5 days/week over a 28-day period, followed by a 28-day recovery period. During the experimental period, clinical signs, body weight, hematologic parameters, serum biochemical parameters, necropsy findings, organ weight, and histopathological findings were examined; neodymium distribution in the major organs and blood, bronchoalveolar lavage fluid (BALF), and oxidative stress in lung tissues were analyzed. Most of the neodymium was found to be deposited in lung tissues, showing a dose-dependent relationship. Infiltration of inflammatory cells and pulmonary alveolar proteinosis (PAP) were the main observations of lung histopathology. Infiltration of inflammatory cells was observed in the 2.5 mg/m3 and higher dose treatment groups. PAP was observed in all treatment groups accompanied by an increase in lung weight, but was observed to a lesser extent in the 0.5 mg/m3 treatment group. In BALF analysis, total cell counts, including macrophages and neutrophils, lactate dehydrogenase, albumin, interleukin-6, and tumor necrosis factor-alpha, increased significantly in all treatment groups. After a 4-week recovery period, these changes were generally reversed in the 0.5 mg/m3 group, but were exacerbated in the 10 mg/m3 group. The lowest-observed-adverse-effect concentration of nano-sized Nd2O3 was determined to be 0.5 mg/m3, and the target organ was determined to be the lung

  9. Magnetic fabric interpretation complicated by inclusions in mafic silicates

    NASA Astrophysics Data System (ADS)

    Lagroix, France; Borradaile, Graham J.

    2000-10-01

    The expected relationships between anisotropy of low-field magnetic susceptibility (AMS) and crystal symmetry of mafic silicates are disturbed by the presence of magnetite inclusions. Measurements of AMS, anisotropy of anhysteretic remanence (AARM) and theoretically predicted bulk susceptibilities from chemical composition all favour the exercise of great caution in the interpretation of preferred orientation distributions of silicates from a rock's AMS. These results pertain mainly to the mafic silicates of lower crustal rocks (pyroxene, orthopyroxene, amphibole) and some of their low-grade metamorphic alterations (serpentine, epidote).

  10. Silicate nephrolithiasis after ingestion of supplements containing silica dioxide.

    PubMed

    Flythe, Jennifer E; Rueda, Jose F; Riscoe, Michael K; Watnick, Suzanne

    2009-07-01

    Silicate calculi are common in some mammals, such as dogs and sheep, but extremely rare in humans. We report a case of silicate calculi in a woman using oral over-the-counter Uncaria tomentosa, Digestive Advantage and FlexProtex supplements. All 3 contained the excipient silica dioxide. Stone analysis showed composition of 100% silicate. The nephrolithiasis promptly abated after discontinuation of the products containing silica, then returned when the patient restarted her supplements. This case emphasizes the importance of stone analysis when obvious causes of nephrolithiasis are unclear and highlights the concerns of using over-the-counter supplements without substantial oversight.

  11. Microstructures of Rare Silicate Stardust from Nova and Supernovae

    NASA Technical Reports Server (NTRS)

    Nguyen, A. N.; Keller, L. P.; Rahman, Z.; Messenger, S

    2011-01-01

    Most silicate stardust analyzed in the laboratory and observed around stellar environments derives from O-rich red giant and AGB stars [1,2]. Supernova (SN) silicates and oxides are comparatively rare, and fewer than 10 grains from no-va or binary star systems have been identified to date. Very little is known about dust formation in these stellar environments. Mineralogical studies of only three O-rich SN [3-5] and no nova grains have been performed. Here we report the microstructure and chemical makeup of two SN silicates and one nova grain.

  12. The Mineralogy of Circumstellar Silicates Preserved in Cometary Dust

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Messenger, S.

    2010-01-01

    Interplanetary dust particles (IDPs) contain a record of the building blocks of the solar system including presolar grains, molecular cloud material, and materials formed in the early solar nebula. Cometary IDPs have remained relatively unaltered since their accretion because of the lack of parent body thermal and aqueous alteration. We are using coordinated transmission electron microscope (TEM) and ion microprobe studies to establish the origins of the various components within cometary IDPs. Of particular interest is the nature and abundance of presolar silicates in these particles because astronomical observations suggest that crystalline and amorphous silicates are the dominant grain types produced in young main sequence stars and evolved O-rich stars. Five circumstellar grains have been identified including three amorphous silicate grains and two polycrystalline aggregates. All of these grains are between 0.2 and 0.5 micrometers in size. The isotopic compositions of all five presolar silicate grains fall within the range of presolar oxides and silicates, having large (17)O-enrichments and normal (18)O/(16)O ratios (Group 1 grains from AGB and RG stars). The amorphous silicates are chemically heterogeneous and contain nanophase FeNi metal and FeS grains in a Mg-silicate matrix. Two of the amorphous silicate grains are aggregates with subgrains showing variable Mg/Si ratios in chemical maps. The polycrystalline grains show annealed textures (equilibrium grains boundaries, uniform Mg/Fe ratios), and consist of 50-100 nm enstatite and pyrrhotite grains with lesser forsterite. One of the polycrystalline aggregates contains a subgrain of diopside. The polycrystalline aggregates form by subsolidus annealing of amorphous precursors. The bulk compositions of the five grains span a wide range in Mg/Si ratios from 0.4 to 1.2 (avg. 0.86). The average Fe/Si (0.40) and S/Si (0.21) ratios show a much narrower range of values and are approximately 50% of their solar

  13. Sensitized photoluminescence of erbium silicate synthesized on porous silicon framework

    NASA Astrophysics Data System (ADS)

    Shen, Hao; Xu, Lingbo; Li, Dongsheng; Yang, Deren

    2017-09-01

    Er silicate/porous silicon (PS) composites with effective sensitized erbium emission at 1.53 μm have been synthesized on the PS framework. Cross-sectional scanning electron microscopy and X-ray diffraction reveal that the PS is coated by Er silicate in composites. Indirect excitation of Er3+ ion luminescence via energy transfer from PS is confirmed. The temperature dependence of Er-related photoluminescence intensity and lifetime is investigated, which concludes a phonon-mediated energy transfer process. The combination of the PS framework and Er silicate provides a possible strategy for practical silicon-based light sources.

  14. Thermally responsive aqueous silicate mixtures and use thereof

    SciTech Connect

    Smith, W.H.; Vinson, E.F.

    1987-02-03

    A method is described of plugging or sealing a zone in a subterranean formation comprising: (a) contacting the zone with an aqueous silicate composition consisting essentially of (i) an aqueous solution containing an alkali metal silicate; and, (ii) a thermally responsive gelation activator selected from the group consisting of lactose, dextrose, fructose, galactose, mannose, mantose, xylose and mixtures thereof; and (b) activating the gelation activator in response to a thermal change in the composition within the formation whereby the silicate composition is caused to form a gel in the zone.

  15. Chemistry of the subalkalic silicic obsidians

    USGS Publications Warehouse

    MacDonald, Ray; Smith, Robert L.; Thomas, John E.

    1992-01-01

    Nonhydrated obsidians are quenched magmatic liquids that record in their chemical compositions details of the tectonic environment of formation and of the differentiation mechanisms that affected their subsequent evolution. This study attempts to analyze, in terms of geologic processes, the compositional variations in the subalkalic silicic obsidians (Si02≥70 percent by weight, molecular (Na2O+K20)>Al2O3). New major- and trace-element determinations of 241 samples and a compilation of 130 published major-element analyses are reported and interpreted. Obsidians from five different tectonic settings are recognized: (1) primitive island arcs, (2) mature island arcs, (3) continental margins, (4) continental interiors, and (5) oceanic extensional zones. Tectonomagmatic discrimination between these groups is successfully made on Nb-Ta, Nb-FeOt and Th-Hf-Ta plots, and compositional ranges and averages for each group are presented. The chemical differences between groups are related to the type of crust in which magmas were generated. With increasingly sialic (continental type) crust, the obsidians show overall enrichment in F, Be, Li, Mo, Nb, Rb, Sn, Ta, U, W, Zn, and the rare-earth elements, and depletion in Mg, Ca, Ba, Co, Sc, Sr, and Zr. They become more potassic, have higher Fe/Mg and F/Cl ratios, and lower Zr/Hf, Nb/Ta, and Th/U ratios. Higher values of total rare-earth elements are accompanied by light rare-earth-element enrichment and pronounced negative Eu anomalies. An attempt is made to link obsidian chemistry to genetic mechanlism. Two broad groups of rocks are distinguished: one generated where crystal-liquid processes dominated (CLPD types), which are the products of crustal anatexis, possibly under conditions of low halogen fugacity, ± crystal fractionation ± magma mixing; and a second group represented by rocks formed in the upper parts of large magma chambers by interplays of crystal fractionation, volatile transfer, magma mixing, and possibly various

  16. Metal/Silicate Partitioning of W, Ge, Ga and Ni: Dependence on Silicate Melt Composition

    NASA Astrophysics Data System (ADS)

    Singletary, S.; Drake, M. J.

    2004-12-01

    Metal/silicate partition coefficients (Dm/s) for siderophile elements are essential to investigations of core formation when used in conjunction with the pattern of elemental abundances in the Earth's mantle (Drake and Righter, 2002; Jones and Drake, 1986; Righter et al. 1997). The partitioning of siderophile elements is controlled by temperature, pressure, oxygen fugacity, and by the compositions of the metal and silicate phases. In this work, we investigate the role of silicate melt composition on the partitioning of the siderophile elements W, Ge, Ga and Ni between metallic and silicate liquid. Experiments were performed in the Experimental Geochemistry Laboratory at the University of Arizona utilizing a non-end loaded piston cylinder apparatus with a barium carbonate pressure medium. Starting materials were created by combining the mafic and silicic compositions of Jaeger and Drake (2000) with Fe powder (~25 wt% of the total mixture) to achieve metal saturation. Small amounts of W, Ge, Ga2O3 and NiO powder (less than 2 wt% each) were also added to the starting compositions. The experiments were contained in a graphite capsule and performed with temperature and pressure fixed at 1400ºC and 1.5 GPa. Experimental run products were analyzed with the University of Arizona Cameca SX50 electron microprobe with four wavelength dispersive spectrometers and a PAP ZAF correction program. All experiments in our set are saturated with metal and silicate liquid, indicating that oxygen fugacity is below IW. Several of the runs also contain a gallium-rich spinel as an additional saturating phase. Quench phases are also present in the silicate liquid in all runs. The experimentally produced liquids have nbo/t values (calculated using the method of Mills, 1993) that range from 1.10 to 2.97. These values are higher than those calculated for the liquids in the Jaeger and Drake (2000) study. The higher nbo/t values are due to uptake of Fe by the melt. The initial silicate

  17. Interstellar Silicate Dust: Modeling and Grain Alignment

    NASA Astrophysics Data System (ADS)

    Das, Indrajit

    We examine some aspects of the alignment of silicate dust grains with respect to the interstellar magnetic field. First, we consider possible observational constraints on the magnetic properties of the grains. Second, we investigate the role of collisions with gas atoms and the production of H2 molecules on the grain surface in the alignment process when the grain is drifting in the gaseous medium. Paramagnetism associated with Fe content in the dust is thought to play a critical role in alignment. Min et al (2007) claimed that the Fe content of the silicate dust can be constrained by the shape of the 10 μm extinction feature. They found low Fe abundances, potentially posing problems for grain alignment theories. We revisit this analysis modeling the grains with irregularly shaped Gaussian Random Sphere (GRS). We give a comprehensive review of all the relevant constraints researchers apply and discuss their effects on the inferred mineralogy. Also, we extend this analysis to examine whether constraints can be placed on the presence of Fe-rich inclusions which could yield "super-paramagnetism". This possibility has long been speculated, but so far observational constraints are lacking. Every time a gas atom collides with a grain, the grain's angular momentum is slightly modified. Likewise when an H2 molecule forms on the surface and is ejected. Here also we model the grain with GRS shape and considered various scenarios about how the colliding gas particles depart the grain. We develop theoretical and computational tools to estimate the torques associated with these aforementioned events for a range of grain drift speeds---from low subsonic to high supersonic speeds. Code results were verified with spherical grain for which analytical results were available. Finally, the above torque results were used to study the grain rotational dynamics. Solving dynamical equations we examine how these torques influence the grain alignment process. Our analysis suggests that

  18. Shear-Induced Fragmentation in Silicic Volcanism

    NASA Astrophysics Data System (ADS)

    Gonnermann, H. M.; Manga, M.

    2003-12-01

    Fragmentation of magma, containing abundant gas bubbles, is considered as the defining characteristic of explosive eruptions. When viscous stresses associated with the growth of bubbles and the flow of the ascending magma exceed the strength of the melt, it breaks into disconnected fragments suspended within an expanding gas phase. While repeated effusive and explosive eruptions for individual volcanoes are common, the dynamics governing the transition between explosive and effusive eruptions remain unclear. Magmas for both types of eruptions originate from sources with similar volatile content, yet effusive lavas erupt considerably more degassed than their explosive counterparts. Recent observations suggest that magma fragmentation may not be restricted to explosive eruptions and we find corroborating evidence of magma fragmentation, reannealing and elongation of fragments into flow banding from obsidians from Big Glass Mountain rhyolite dome, California. One mechanism for degassing during magma ascent is the generation of intermittent permeable fracture networks through non-explosive fragmentation near the conduit walls. To gain insight into the mechanics governing fragmentation in silicic volcanoes, we have developed a numerical model for magma ascent in the volcanic conduit. The ascending magma (melt + bubbles) is modelled as steady, isothermal flow of a single-phase liquid at constant mass flux in a cylindrical conduit of constant radius. We specify a pressure, number density of bubbles, and relaxed Newtonian melt viscosity at the base of the conduit and solve the joint problem of bubble growth and magma ascent. Rather than include the transition to fragmentation and flow of fragmented magma, we determine the ascent distance above the conduit entry at which magma fragmentation by viscous shear should first occur. The model is quasi-one-dimensional and for a given depth computes the radially varying vertical component of magma velocity. We show that shear

  19. Interstellar silicate analogs for grain-surface reaction experiments: Gas-phase condensation and characterization of the silicate dust grains

    SciTech Connect

    Sabri, T.; Jäger, C.; Gavilan, L.; Lemaire, J. L.; Vidali, G.; Henning, T.

    2014-01-10

    Amorphous, astrophysically relevant silicates were prepared by laser ablation of siliceous targets and subsequent quenching of the evaporated atoms and clusters in a helium/oxygen gas atmosphere. The described gas-phase condensation method can be used to synthesize homogeneous and astrophysically relevant silicates with different compositions ranging from nonstoichiometric magnesium iron silicates to pyroxene- and olivine-type stoichiometry. Analytical tools have been used to characterize the morphology, composition, and spectral properties of the condensates. The nanometer-sized silicate condensates represent a new family of cosmic dust analogs that can generally be used for laboratory studies of cosmic processes related to condensation, processing, and destruction of cosmic dust in different astrophysical environments. The well-characterized silicates comprising amorphous Mg{sub 2}SiO{sub 4} and Fe{sub 2}SiO{sub 4}, as well as the corresponding crystalline silicates forsterite and fayalite, produced by thermal annealing of the amorphous condensates, have been used as real grain surfaces for H{sub 2} formation experiments. A specifically developed ultra-high vacuum apparatus has been used for the investigation of molecule formation experiments. The results of these molecular formation experiments on differently structured Mg{sub 2}SiO{sub 4} and Fe{sub 2}SiO{sub 4} described in this paper will be the topic of the next paper of this series.

  20. Effects of Incorporating High-Volume Fly Ash into Tricalcium Silicate on the Degree of Silicate Polymerization and Aluminum Substitution for Silicon in Calcium Silicate Hydrate

    PubMed Central

    Bae, Sungchul; Taylor, Rae; Kilcoyne, David; Moon, Juhyuk; Monteiro, Paulo J. M.

    2017-01-01

    This study assesses the quantitative effects of incorporating high-volume fly ash (HVFA) into tricalcium silicate (C3S) paste on the hydration, degree of silicate polymerization, and Al substitution for Si in calcium silicate hydrate (C–S–H). Thermogravimetric analysis and isothermal conduction calorimetry showed that, although the induction period of C3S hydration was significantly extended, the degree of hydration of C3S after the deceleration period increased due to HVFA incorporation. Synchrotron-sourced soft X-ray spectromicroscopy further showed that most of the C3S in the C3S-HVFA paste was fully hydrated after 28 days of hydration, while that in the pure C3S paste was not. The chemical shifts of the Si K edge peaks in the near-edge X-ray fine structure of C–S–H in the C3S-HVFA paste directly indicate that Al substitutes for Si in C–S–H and that the additional silicate provided by the HVFA induces an enhanced degree of silicate polymerization. This new spectromicroscopic approach, supplemented with 27Al and 29Si magic-angle spinning nuclear magnetic resonance spectroscopy and transmission electron microscopy, turned out to be a powerful characterization tool for studying a local atomic binding structure of C–S–H in C3S-HVFA system and presented results consistent with previous literature. PMID:28772490

  1. Metal-Silicate Segregation in Asteroidal Meteorites

    NASA Technical Reports Server (NTRS)

    Herrin, Jason S.; Mittlefehldt, D. W.

    2006-01-01

    A fundamental process of planetary differentiation is the segregation of metal-sulfide and silicate phases, leading eventually to the formation of a metallic core. Asteroidal meteorites provide a glimpse of this process frozen in time from the early solar system. While chondrites represent starting materials, iron meteorites provide an end product where metal has been completely concentrated in a region of the parent asteroid. A complimentary end product is seen in metal-poor achondrites that have undergone significant igneous processing, such as angrites, HED's and the majority of aubrites. Metal-rich achondrites such as acapulcoite/lodranites, winonaites, ureilites, and metal-rich aubrites may represent intermediate stages in the metal segregation process. Among these, acapulcoite-lodranites and ureilites are examples of primary metal-bearing mantle restites, and therefore provide an opportunity to observe the metal segregation process that was captured in progress. In this study we use bulk trace element compositions of acapulcoites-lodranites and ureilites for this purpose.

  2. The di- and tricalcium silicate dissolutions

    SciTech Connect

    Nicoleau, L.; Nonat, A.; Perrey, D.

    2013-05-15

    In this study, a specially designed reactor connected to an ICP spectrometer enabled the careful determination of the dissolution rates of C{sub 3}S, C{sub 2}S and CaO, respectively, over a broad range of concentration of calcium and silicates under conditions devoid of C–S–H. The kinetic laws, bridging the dissolution rates and the undersaturations, were obtained after extrapolation of rate zero allowing the estimation of the true experimental solubility products of C{sub 3}S (K{sub sp} = 9.6 · 10{sup −23}), C{sub 2}S (K{sub sp} = 4.3 · 10{sup −18}) and CaO (K{sub sp} = 9.17 · 10{sup −6}). The latter are then compared to the solubilities calculated from the enthalpies of formation. We propose that the observed deviations result from the protonation of the unsaturated oxygen atoms present at the surface of these minerals. Hydration rates measured in cement pastes or in C{sub 3}S pastes are in excellent agreement with the kinetic law found in this study for C{sub 3}S under conditions undersaturated with respect to C–S–H.

  3. Calcium Isotopic Composition of Bulk Silicate Earth

    NASA Astrophysics Data System (ADS)

    Kang, J.; Ionov, D. A.; Liu, F.; Zhang, C.; Zhang, Z.; Huang, F.

    2016-12-01

    Ca isotopes are used to study the accretion history of the Earth and terrestrial planets, but, Ca isotopic composition of the Bulk Silicate Earth (BSE) remains poorly constrained [1]. To better understand the Ca isotopic composition of BSE, we analyzed 22 well studied peridotite xenoliths from Tariat (Mongolia), Vitim (southern Siberia) and Udachnaya (Siberian Craton). These samples include both fertile and highly depleted garnet and spinel peridotites that show no or only minor post-melting metasomatism or alteration. Ca isotope measurements were done on a Triton-TIMS using double spike method at the Guangzhou Institute of Geochemistry, CAS. The data are reported as δ44/40Ca (relative to NIST SRM 915a). Results for geostandards are consistent with those from other laboratories. 2 standard deviations of SRM 915a analyses are 0.13‰ (n=48). δ44/40Ca of both and fertile and refractory peridotites range from 0.79 to 1.07‰ producing an average of 0.93±0.12‰ (2SD). This value defines the Ca isotopic composition of the BSE, which is consistent with the average δ44/40Ca of oceanic basalts ( 0.90‰)[2,3]. [1] Huang et al (2010) EPSL 292; [2] Valdes et al (2014) EPSL 394; [3]DePaolo (2004) RMG 55.

  4. Hydrogen mobility in transition zone silicates

    NASA Astrophysics Data System (ADS)

    Caracas, R.; Panero, W. R.

    2016-12-01

    Hydrogen defects in mantle silicates adopt a variety of charge-balanced defects, including VMg''+2(H*), VSi''''+4(H*), and VSi'+(Mg+2H*). Constraining the defect mechanism experimentally can be quite difficult, as it relies almost entirely on vibrational spectroscopy whose interpretation can often be controversial. Here we use a computational alternative: we study the above-mentioned defect mechanisms using molecular dynamics simulations based on the density-functional theory, in the VASP implementation. We perform isokinetical NVT simulations over a 1500 - 2500K temperature range using supercells containing 16 equivalent formula units of Mg2SiO4. Our results show that temperature has a tremendous effect on mobility. H is significantly more mobile when incorporated as VMg''+2H* defects than as hydrogarnet defects and that VMg''+2H* defects are more mobile in wadsleyite than ringwoodite. This result is the opposite from the proton conductivity inferences of Yoshino et al. [2008] and Huang et al [2006], as well as the observed increase in electrical conductivity with depth through the transition zone [e.g. Kuvshinov et al, 2005; Olsen 1998]. Over the simulation time of several tens of picoseconds the H travel over several lattice sites. However, during its path it spends a considerable amount of time pinned in the defect sites. The lowest mobility is for the VSi''''+4(H*) defect, where the H atoms remain inside the octahedron from which they replaced the Si.

  5. Lithologic mapping of silicate rocks using TIMS

    NASA Technical Reports Server (NTRS)

    Gillespie, A. R.

    1986-01-01

    Common rock-forming minerals have thermal infrared spectral features that are measured in the laboratory to infer composition. An airborne Daedalus scanner (TIMS) that collects six channels of thermal infrared radiance data (8 to 12 microns), may be used to measure these same features for rock identification. Previously, false-color composite pictures made from channels 1, 3, and 5 and emittance spectra for small areas on these images were used to make lithologic maps. Central wavelength, standard deviation, and amplitude of normal curves regressed on the emittance spectra are related to compositional information for crystalline igneous silicate rocks. As expected, the central wavelength varies systematically with silica content and with modal quartz content. Standard deviation is less sensitive to compositional changes, but large values may result from mixed admixture of vegetation. Compression of the six TIMS channels to three image channels made from the regressed parameters may be effective in improving geologic mapping from TIMS data, and these synthetic images may form a basis for the remote assessment of rock composition.

  6. Reactivity and applications of layered silicates and layered double hydroxides.

    PubMed

    Selvam, Thangaraj; Inayat, Alexandra; Schwieger, Wilhelm

    2014-07-21

    Layered materials, such as layered sodium silicates and layered double hydroxides (LDHs), are well-known for their remarkable adsorption, intercalation and swelling properties. Their tunable interlayers offer an interesting avenue for the fabrication of pillared nanoporous materials, organic-inorganic hybrid materials and catalysts or catalyst supports. This perspective article provides a summary of the reactivity and applications of layered materials including aluminium-free layered sodium silicates (kanemite, ilerite (RUB-18 or octosilicate) and magadiite) and layered double hydroxides (LDHs). Recent developments in the use of layered sodium silicates as precursors for the preparation of various porous, functional and catalytic materials including zeolites, mesoporous materials, pillared layered silicates, organic-inorganic nanocomposites and synthesis of highly dispersed nanoparticles supported on silica are reviewed in detail. Along this perspective, we have attempted to illustrate the reactivity and transformational potential of LDHs in order to deduce the main differences and similarities between these two types of layered materials.

  7. Relationship Between Carbon and Silicates in Cometary Dust

    NASA Astrophysics Data System (ADS)

    Starkey, N. A.; Franchi, I. A.; Salge, T.; Brearley, A. J.

    2015-07-01

    An ultracarbonaceous IDP fragment is analysed with combined high spatial resolution SEM-EDX and H, C, O isotope mapping to investigate the relationship between the organic matter matrix and the small silicate grains contained within.

  8. Characterization of iron-phosphate-silicate chemical garden structures.

    PubMed

    Barge, Laura M; Doloboff, Ivria J; White, Lauren M; Stucky, Galen D; Russell, Michael J; Kanik, Isik

    2012-02-28

    Chemical gardens form when ferrous chloride hydrate seed crystals are added or concentrated solutions are injected into solutions of sodium silicate and potassium phosphate. Various precipitation morphologies are observed depending on silicate and phosphate concentrations, including hollow plumes, bulbs, and tubes. The growth of precipitates is controlled by the internal osmotic pressure, fluid buoyancy, and membrane strength. Additionally, rapid bubble-led growth is observed when silicate concentrations are high. ESEM/EDX analysis confirms compositional gradients within the membranes, and voltage measurements across the membranes during growth show a final potential of around 150-200 mV, indicating that electrochemical gradients are maintained across the membranes as growth proceeds. The characterization of chemical gardens formed with iron, silicate, and phosphate, three important components of an early earth prebiotic hydrothermal system, can help us understand the properties of analogous structures that likely formed at submarine alkaline hydrothermal vents in the Hadean-structures offering themselves as the hatchery of life.

  9. Metal-silicate catalysts: Single site, mesoporous systems without templates

    SciTech Connect

    Barnes, Craig E.; Sharp, Katherine; Albert, Austin A; Abbott, Joshua; Peretich, Michael E; Fulvio, Pasquale; Ciesielski, Peter N.; Donohoe, Bryon S.

    2015-06-01

    The textural properties of a family of silicate and mixed metal-silicate materials prepared by a nonaqueous sol-gel reaction involving the cubic silicate Si8O20(SnMe3)8 and metal chlorides MCl4 (M = Si, Ti, Zr) cross-linking reagents are described. Nitrogen adsorption isotherm data is presented and surface area and pore size distribution analyses for several examples of these materials are developed and correlated with the ratio of cross-linking reagent and the cubic silicate building block at the time of synthesis. Significant surface area and pore size distributions that shift to higher pore diameters are observed as the ratio of cross-linking reagent-to-cubic building block increases. A simple strategy for simultaneously controlling the porosity of these matrices while homogeneously dispersing identical metal centers on their surfaces for next generation catalysts is described.

  10. Silicate Urolithiasis during Long-Term Treatment with Zonisamide

    PubMed Central

    Taguchi, Satoru; Nose, Yorito; Sato, Toshikazu; Kobayashi, Teruaki; Takaya, Kanami; Homma, Yukio

    2013-01-01

    Silicate urinary calculi are rare in humans, with an incidence of 0.2% of all urinary calculi. Most cases were related to excess ingestion of silicate, typically by taking magnesium trisilicate as an antacid for peptic ulcers over a long period of time; however, there also existed unrelated cases, whose mechanism of development remains unclear. On the other hand, zonisamide, a newer antiepileptic drug, is one of the important causing agents of iatrogenic urinary stones in patients with epilepsy. The supposed mechanism is that zonisamide induces urine alkalinization and then promotes crystallization of urine components such as calcium phosphate by inhibition of carbonate dehydratase in renal tubular epithelial cells. Here, we report a case of silicate urolithiasis during long-term treatment with zonisamide without magnesium trisilicate intake and discuss the etiology of the disease by examining the silicate concentration in his urine. PMID:23935637

  11. Synthesis and thermal stability studies of a series of metastable Dion–Jacobson double-layered neodymium-niobate perovskites

    SciTech Connect

    Josepha, Elisha A.; Farooq, Sara; Mitchell, Cinnamon M.; Wiley, John B.

    2014-08-15

    The Dion–Jacobson double-layered perovskite, RbNdNb{sub 2}O{sub 7}, is used as a precursor to synthesize the series ANdNb{sub 2}O{sub 7} (A=H, Li, Na, K, NH{sub 4}, Ag), and (MCl)NdNb{sub 2}O{sub 7} (M=Mn, Fe, Cu) through ion-exchange reactions ≤400 °C. Thermal stability studies indicated that most of these compounds are metastable. A combination of X-ray powder diffraction and differential thermal analysis were used to determine various low temperature decomposition pathways; these pathways were very dependent on the interlayer species. Overall the ANdNb{sub 2}O{sub 7} series was found to be less stable than the corresponding lanthanides, ALaNb{sub 2}O{sub 7}. - Graphical abstract: A new series of topochemically-prepared metastable neodymium-containing layered perovskites are studied. - Highlights: • A series of new layered neodymium containing perovskites were synthesized by ion exchange. • Products were studied by variable temperature X-ray diffraction and thermal analysis. • Most of the series are metastable showing exothermic transitions on decomposition. • The Nd compounds are less stable due to the smaller size of the Nd relative to La.

  12. Assessment of optical path length in tissue using neodymium and water absorptions for application to near-infrared spectroscopy.

    PubMed

    Nighswander-Rempel, Stephen P; Kupriyanov, Valery V; Shaw, R Anthony

    2005-01-01

    Quantitative analysis of blood oxygen saturation using near-IR spectroscopy is made difficult by uncertainties in both the absolute value and the wavelength dependence of the optical path length. We introduce a novel means of assessing the wavelength dependence of path length, exploiting the relative intensities of several absorptions exhibited by an exogenous contrast agent (neodymium). Combined with a previously described method that exploits endogenous water absorptions, the described technique estimates the absolute path length at several wavelengths throughout the visible/near-IR range of interest. Isolated rat hearts (n = 11) are perfused separately with Krebs-Henseleit buffer (KHB) and a KHB solution to which neodymium had been added, and visible/near-IR spectra are acquired using an optical probe made up of emission and collection fibers in concentric rings of diameters 1 and 3 mm, respectively. Relative optical path lengths at 520, 580, 679, 740, 800, 870, and 975 nm are 0.41+/-0.13, 0.49+/-0.21, 0.90+/-0.09, 0.94+/-0.01, 1.00, 0.84+/-0.01, and 0.78+/-0.08, respectively. The absolute path length at 975 nm is estimated to be 3.8+/-0.6 mm, based on the intensity of the water absorptions and the known tissue water concentration. These results are strictly valid only for the experimental geometry applied here.

  13. Global flows of critical metals necessary for low-carbon technologies: the case of neodymium, cobalt, and platinum.

    PubMed

    Nansai, Keisuke; Nakajima, Kenichi; Kagawa, Shigemi; Kondo, Yasushi; Suh, Sangwon; Shigetomi, Yosuke; Oshita, Yuko

    2014-01-01

    This study, encompassing 231 countries and regions, quantifies the global transfer of three critical metals (neodymium, cobalt, and platinum) considered vital for low-carbon technologies by means of material flow analysis (MFA), using trade data (BACI) and the metal contents of trade commodities, resolving the optimization problem to ensure the material balance of the metals within each country and region. The study shows that in 2005 international trade led to global flows of 18.6 kt of neodymium, 154 kt of cobalt, and 402 t of platinum and identifies the main commodities and top 50 bilateral trade links embodying these metals. To explore the issue of consumption efficiency, the flows were characterized according to the technological level of each country or region and divided into three types: green ("efficient use"), yellow ("moderately efficient use"), and red ("inefficient use"). On this basis, the shares of green, yellow, and red flows in the aggregate global flow of Nd were found to be 1.2%, 98%, and 1.2%, respectively. For Co, the respective figures are 53%, 28%, and 19%, and for Pt 15%, 84%, and 0.87%. Furthermore, a simple indicator focusing on the composition of the three colored flows for each commodity was developed to identify trade commodities that should be prioritized for urgent technical improvement to reduce wasteful use of the metals. Based on the indicator, we discuss logical, strategic identification of the responsibilities and roles of the countries involved in the global flows.

  14. Electrochemical extraction of neodymium by co-reduction with aluminum in LiCl-KCl molten salt

    NASA Astrophysics Data System (ADS)

    Yan, Yong-De; Xu, Yan-Lu; Zhang, Mi-Lin; Xue, Yun; Han, Wei; Huang, Ying; Chen, Qiong; Zhang, Zhi-Jian

    2013-02-01

    The electrochemical behavior of Nd(III) ions in LiCl-KCl and LiCl-KCl-AlCl3 melts on a Mo electrode at 723 K was studied by various electrochemical techniques. The results showed that Nd(III) ions are reduced to Nd(0) through two consecutive steps, and the underpotential deposition of neodymium on pre-deposited Al electrode formed two kinds of Al-Nd intermetallic compounds in LiCl-KCl-AlCl3 solutions. The electrochemical extraction of neodymium was carried out in LiCl-KCl-AlCl3 melts on a Mo electrode at 873 K by potentiostatic and galvanostatic electrolysis. The extraction efficiency was 99.25% after potentiostatic electrolysis for 30 h. Al-Li-Nd bulk alloy was obtained by galvanostatic electrolysis. X-ray diffraction (XRD) suggested that Al2Nd and Al3Nd phases were formed in Al-Li-Nd alloy. The microstructure and micro-zone chemical analysis of Al-Li-Nd alloy were characterized by scanning electron microscopy (SEM) with energy dispersive spectrometry (EDS), respectively.

  15. Effect of the addition of low rare earth elements (lanthanum, neodymium, cerium) on the biodegradation and biocompatibility of magnesium.

    PubMed

    Willbold, Elmar; Gu, Xuenan; Albert, Devon; Kalla, Katharina; Bobe, Katharina; Brauneis, Maria; Janning, Carla; Nellesen, Jens; Czayka, Wolfgang; Tillmann, Wolfgang; Zheng, Yufeng; Witte, Frank

    2015-01-01

    Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium-rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates. Copyright © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  16. Efficient Recovery of Neodymium in Acidic System by Free-Standing Dual-Template Docking Oriented Ionic Imprinted Mesoporous Films.

    PubMed

    Zheng, Xudong; Zhang, Fusheng; Liu, Enli; Xu, Xuechao; Yan, Yongsheng

    2017-01-11

    Neodymium (Nd) is critical component of sintered neodymium magnets. Separation of Nd from consumer magnets has attracted a widespread attention. In this paper, we presented free-standing ionic imprinted mesoporous film materials for facile and highly efficient targeted separation of Nd from permanent magnets by dual-template docking oriented ionic imprinting (DTD-OII) method. DTD-OII is based on dual-template docking oriented molecular imprinting. Compared with conventional imprinting, this novel strategy does not need extra steps, but significantly advance imprinted efficiency. With optimization of functional monomer, our free-standing dual-template docking oriented ionic imprinted mesoporous films exhibit excellent adsorption of Nd by solid-liquid extraction. The Nd adsorption capacity for optimized films was 34.98 mg g(-1) under pH = 3.0. The distribution coefficient of Nd was 636 mL g(-1), which indicates films possess significantly selectivity of Nd. In addition, efficient dual-template docking oriented ionic imprinting makes films demonstrating an outstanding of reusability by cycle test, which appreciating their potential for industrial application.

  17. Magnetic field strength and reproducibility of neodymium magnets useful for transcranial static magnetic field stimulation of the human cortex.

    PubMed

    Rivadulla, Casto; Foffani, Guglielmo; Oliviero, Antonio

    2014-07-01

    The application of transcranial static magnetic field stimulation (tSMS) in humans reduces the excitability of the motor cortex for a few minutes after the end of stimulation. However, when tSMS is applied in humans, the cortex is at least 2 cm away, so most of the strength of the magnetic field will not reach the target. The main objective of the study was to measure the strength and reproducibility of static magnetic fields produced by commercial neodymium magnets. We measured the strength and reproducibility of static magnetic fields produced by four different types of neodymium cylindrical magnets using a magnetic field-to-voltage transducer. Magnetic field strength depended on magnet size. At distances <1.5 cm, the magnetic field strength was affected by the presence of central holes (potentially useful for recording electroencephalograms). At distances >1.5 cm, the measurements made on the cylinder axis and 1.5 cm off the axis were comparable. The reproducibility of the results (i.e., the consistency of the field strength across magnets of the same size) was very high. These measurements offer a quantitative empirical reference for developing devices useful for tSMS protocols in both humans and animals. © 2013 International Neuromodulation Society.

  18. Cathodic processes of neodymium(iii) in LiF-NdF3-Nd2O3 melts.

    PubMed

    Huang, Chao; Liu, Xiaolong; Gao, Yuan; Liu, Shizhe; Li, Bing

    2016-08-15

    In this paper, cyclic voltammetry and square wave voltammetry are applied to characterize the cathode processes of neodymium ions on a W electrode in LiF-NdF3 melts with or without the metal Nd. The results indicate that neodymium ions in the LiF-NdF3 (2 wt%) melt are reduced in two steps, i.e. Nd(3+) → Nd(2+) and Nd(2+) → Nd(0), corresponding to starting reduction potentials of 0.35 V vs. Li(+)/Li and 0.1 V vs. Li(+)/Li, respectively. The Nd(3+) → Nd(2+) process is controlled by mass transfer and the Nd(2+) → Nd(0) process is controlled by both an interfacial step and mass transfer. But in the LiF-NdF3 melt with excess metal Nd equilibrium, the kinetics of the above two processes are controlled by mass transfer. After potentiostatic electrolysis at 0.35 V in the LiF-NdF3-Nd2O3 melt NdF2 is formed on the Mo cathode, and metallic Nd is obtained by potentiostatic electrolysis at 0.1 V in the LiF-NdF3-Nd2O3-Nd melt, which validates the above electrochemical reduction results.

  19. History of Nebular Processing Traced by Silicate Stardust in IDPS

    NASA Technical Reports Server (NTRS)

    Messenger, Scott R.; Keller, L. P.; Nakamura-Messenger, K.

    2010-01-01

    Chondritic porous interplanetary dust particles (CP-IDPs) may be the best preserved remnants of primordial solar system materials, in part because they were not affected by parent body hydrothermal alteration. Their primitive characteristics include fine grained, unequilibrated, anhydrous mineralogy, enrichment in volatile elements, and abundant molecular cloud material and silicate stardust. However, while the majority of CP-IDP materials likely derived from the Solar System, their formation processes and provenance are poorly constrained. Stardust abundances provide a relative measure of the extent of processing that the Solar System starting materials has undergone in primitive materials. For example, among primitive meteorites silicate stardust abundances vary by over two orders of magnitude (less than 10-200 ppm). This range of abundances is ascribed to varying extents of aqueous processing in the meteorite parent bodies. The higher average silicate stardust abundances among CP-IDPs (greater than 375 ppm) are thus attributable to the lack of aqueous processing of these materials. Yet, silicate stardust abundances in IDPs also vary considerably. While the silicate stardust abundance in IDPs having anomalous N isotopic compositions was reported to be 375 ppm, the abundance in IDPs lacking N anomalies is less than 10 ppm. Furthermore, these values are significantly eclipsed among some IDPs with abundances ranging from 2,000 ppm to 10,000 ppm. Given that CP-IDPs have not been significantly affected by parent body processes, the difference in silicate stardust abundances among these IDPs must reflect varying extents of nebular processing. Here we present recent results of a systematic coordinated mineralogical/isotopic study of large cluster IDPs aimed at (1) characterizing the mineralogy of presolar silicates and (2) delineating the mineralogical and petrographic characteristics of IDPs with differing silicate stardust abundances. One of the goals of this study is

  20. Silicate Removal in Aluminum Hydroxide Co-Precipitation Process

    PubMed Central

    Tokoro, Chiharu; Suzuki, Shinya; Haraguchi, Daisuke; Izawa, Sayaka

    2014-01-01

    The removal mechanisms of silicate using an aluminum hydroxide co-precipitation process was investigated and compared with an adsorption process, in order to establish an effective and validated method for silicate removal from wastewater. Adsorption isotherms, XRD and FT-IR analyses showed that silicate uptake occurred by adsorption to boehmite for initial Si/Al molar ratios smaller than two, but by precipitation of poorly crystalline kaolinite for the ratios larger than two, in both co-precipitation and adsorption processes. Silicate was removed by two steps: (i) an initial rapid uptake in a few seconds; and (ii) a slow uptake over several hours in both processes. The uptake rate in the first step was higher in the co-precipitation process than in adsorption process, presumably due to increased silicate adsorption to boehmite and rapid precipitation of kaolinite. These results suggest that silicate removal using aluminum salts could be effectively achieved if the pH adjustment and aluminum concentration are strictly controlled. PMID:28788501

  1. High Pressure/Temperature Metal Silicate Partitioning of Tungsten

    NASA Technical Reports Server (NTRS)

    Shofner, G. A.; Danielson, L.; Righter, K.; Campbell, A. J.

    2010-01-01

    The behavior of chemical elements during metal/silicate segregation and their resulting distribution in Earth's mantle and core provide insight into core formation processes. Experimental determination of partition coefficients allows calculations of element distributions that can be compared to accepted values of element abundances in the silicate (mantle) and metallic (core) portions of the Earth. Tungsten (W) is a moderately siderophile element and thus preferentially partitions into metal versus silicate under many planetary conditions. The partitioning behavior has been shown to vary with temperature, silicate composition, oxygen fugacity, and pressure. Most of the previous work on W partitioning has been conducted at 1-bar conditions or at relatively low pressures, i.e. <10 GPa, and in two cases at or near 20 GPa. According to those data, the stronger influences on the distribution coefficient of W are temperature, composition, and oxygen fugacity with a relatively slight influence in pressure. Predictions based on extrapolation of existing data and parameterizations suggest an increased pressured dependence on metal/ silicate partitioning of W at higher pressures 5. However, the dependence on pressure is not as well constrained as T, fO2, and silicate composition. This poses a problem because proposed equilibration pressures for core formation range from 27 to 50 GPa, falling well outside the experimental range, therefore requiring exptrapolation of a parametereized model. Higher pressure data are needed to improve our understanding of W partitioning at these more extreme conditions.

  2. The application of silicon and silicates in dentistry: a review.

    PubMed

    Lührs, A-K; Geurtsen, Werner

    2009-01-01

    Silicates and silicate-based compounds are frequently used materials in dentistry. One of their major applications is their use as fillers in different dental filling materials such as glass-ionomer cements, compomers, composites, and adhesive systems. In these materials, the fillers react with acids during the setting process or they improve the mechanical properties by increasing physical resistance, thermal expansion coefficient and radiopacity in acrylic filling materials. They also reduce polymerization shrinkage, and increase esthetics as well as handling properties. Furthermore, silicates are used for the tribochemical silication of different surfaces such as ceramics or alloys. The silicate layer formed in this process is the chemical basis for silanes that form a bond between this layer and the organic composite matrix. It also provides a micromechanical bond between the surface of the material and the composite matrix. Silicates are also a component of dental ceramics, which are frequently used in dentistry, for instance for veneers, inlays, and onlays, for denture teeth, and for full-ceramic crowns or as crown veneering materials.

  3. LOW-TEMPERATURE CRYSTALLIZATION OF AMORPHOUS SILICATE IN ASTROPHYSICAL ENVIRONMENTS

    SciTech Connect

    Tanaka, Kyoko K.; Yamamoto, Tetsuo; Kimura, Hiroshi

    2010-07-01

    We construct a theoretical model for low-temperature crystallization of amorphous silicate grains induced by exothermic chemical reactions. As a first step, the model is applied to the annealing experiments, in which the samples are (1) amorphous silicate grains and (2) amorphous silicate grains covered with an amorphous carbon layer. We derive the activation energies of crystallization for amorphous silicate and amorphous carbon from the analysis of the experiments. Furthermore, we apply the model to the experiment of low-temperature crystallization of an amorphous silicate core covered with an amorphous carbon layer containing reactive molecules. We clarify the conditions of low-temperature crystallization due to exothermic chemical reactions. Next, we formulate the crystallization conditions so as to be applicable to astrophysical environments. We show that the present crystallization mechanism is characterized by two quantities: the stored energy density Q in a grain and the duration of the chemical reactions {tau}. The crystallization conditions are given by Q>Q{sub min} and {tau} < {tau}{sub cool} regardless of details of the reactions and grain structure, where {tau}{sub cool} is the cooling timescale of the grains heated by exothermic reactions, and Q{sub min} is minimum stored energy density determined by the activation energy of crystallization. Our results suggest that silicate crystallization occurs in wider astrophysical conditions than hitherto considered.

  4. Electrical conductivity of silicate liquids and a magma ocean dynamo

    NASA Astrophysics Data System (ADS)

    Stixrude, Lars; Scipioni, Roberto

    2017-04-01

    Are silicate dynamos possible? So far planetary dynamos seated in silicate material are unknown. Several lines of evidence motivate the consideration of a silicate dynamo in the early Earth: 1) Paleomagnetic evidence of a very early dynamo-generated field 2) models of the early thermal state of Earth in which the mantle may have been too hot to permit a core-generated magnetic field, and 3) the possibility of a deep and thick basal magma ocean. The key requirement is that the electrical conductivity σ of silicate liquids be sufficiently large at the relevant high pressure-temperature conditions (σ > 1000 S/m). Despite its importance, σ of silicate liquids is unknown above a few GPa in pressure, and measured values at low pressure are far too small to support a dynamo. However, observations of reflectivity from oxide liquids in shock wave experiments suggest a different mechanism of conductivity at high pressure (electrons, rather than ions). We have used ab initio molecular dynamics simulations to compute from first principles the value of σ at extreme conditions in systems with compositions that are simple (SiO2) and rich (MgO-FeO-CaO-Al2O3-Na2O-SiO2). We use DFT+U with and without spin polarization combined with the Kubo-Greenwood formula. We find that the value of σ exceeds the minimum requirements and that a silicate dynamo seated in a basal magma ocean is viable.

  5. Cometary crystalline silicate before and after perihelion passage II

    NASA Astrophysics Data System (ADS)

    Ootsubo, Takafumi

    2014-01-01

    Crystalline silicate is often observed in comets as an 11.3-micron resonant emission feature, and may be used for probing the early solar nebula. Because the formation of the crystalline silicate requires high temperature, they are thought to have been born from amorphous silicate at the inner region, and then transported toward the outer regions where comets were born. This transportation can produce the difference in the crystalline fraction in the cometary silicate dust between two dynamical types of comets, Oort-cloud comets (OCs) and Ecliptic comets (ECs), due to the different heliocentric distances of their birth places. The study of peak wavelengths in crystalline features is important to investigate the conditions of the crystalline silicate formation as well. Thus far, we don't have enough observational samples of OCs. Fortunately, we can observe comet C/2012 K1 (PanSTARRS) along with C/2013 A1 (Siding Spring) in this semester. In particular, the comet C/2012 K1 (PanSTARRS) is a bright and good target for this silicate peak feature study. Observations at pre- and post-perihelion provide us precious information on the dust evolution of the comet.

  6. Silicates in orthopedics and bone tissue engineering materials.

    PubMed

    Zhou, Xianfeng; Zhang, Nianli; Mankoci, Steven; Sahai, Nita

    2017-07-01

    Following the success of silicate-based glasses as bioactive materials, silicates are believed to play important roles in promoting bone formation and have therefore been considered to provide a hydroxyapatite (HAP) surface layer capable of binding to bone as well as potentially being a pro-osteoinductive factor. Natural silicate minerals and silicate-substituted HAPs are also being actively investigated as orthopaedic bone and dental biomaterials for application in tissue engineering. However, the mechanisms for the proposed roles of silicate in these materials have not been fully understood and are controversial. Here, we review the potential roles of silicate for bone tissue engineering applications and recent breakthroughs in identifying the cellular-level molecular mechanisms for the osteoinductivity of silica. The goal of this article is to inspire new ideas for the rational design of third-generation cell-and gene-affecting biomaterials. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 105A: 2090-2102, 2017. © 2017 Wiley Periodicals, Inc.

  7. Metal/Silicate Partitioning of P, Ga, and W at High Pressures and Temperatures: Dependence on Silicate Melt Composition

    NASA Technical Reports Server (NTRS)

    Bailey, Edward; Drake, Michael J.

    2004-01-01

    The distinctive pattern of element concentrations in the upper mantle provides essential evidence in our attempts to understand the accretion and differentiation of the Earth (e.g., Drake and Righter, 2002; Jones and Drake, 1986; Righter et al., 1997; Wanke 1981). Core formation is best investigated through use of metal/silicate partition coefficients for siderophile elements. The variables influencing partition coefficients are temperature, pressure, the major element compositions of the silicate and metal phases, and oxygen fugacity. Examples of studies investigating the effects of these variables on partitioning behavior are: composition of the metal phase by Capobianco et al. (1999) and Righter et al. (1997); silicate melt composition by Watson (1976), Walter and Thibault (1995), Hillgren et al. (1996), Jana and Walker (1997), and Jaeger and Drake (2000); and oxygen fugacity by Capobianco et al. (1999), and Walter and Thibault (1995). Here we address the relative influences of silicate melt composition, pressure and temperature.

  8. Near-Infrared Neodymium Tag for Quantifying Targeted Biomarker and Counting Its Host Circulating Tumor Cells.

    PubMed

    Liu, Chunlan; Lu, Shu; Yang, Limin; Chen, Peijie; Bai, Peiming; Wang, Qiuquan

    2017-09-05

    Quantitative information on a targeted analyte in a complex biological system is the most basic premise for understanding its involved mechanisms, and thus precise diagnosis of a disease if it is a so-called biomarker. Here, we designed and synthesized a neodymium (Nd)-cored tag [1,4,7,10-tetraazacyclododecane-1,4,7-trisacetic acid (DOTA)-Nd complex together with a light-harvesting antenna aminofluorescein (AMF, λex/em = 494/520 nm), AMF-DOTA-Nd] with duplex signals, second near-infrared (NIR) window luminescence (λem = 1065 nm, 2.5 μs), and stable isotopic mass ((142)Nd). AMF-DOTA-Nd covalently linked with a urea-based peptidomimetic targeting group, 2-[3-(1,3-dicarboxypropyl)-ureido]pentanedioic acid (DUPA)-8-Aoc-Phe-Phe-Cys (DUPAaFFC) (DUPAaFFC-AMF-DOTA-Nd), allowing us to detect and quantify prostate-specific membrane antigen (PSMA) and its splice variants (total PSMA, tPSMA), which was set as an example of targeted biomarkers in this study, using NIR and inductively coupled plasma mass spectrometry (ICPMS) with the limit of detection (LOD) (3σ) of 0.3 ng/mL. When it was applied to the analysis of 80 blood samples from prostate cancer (PCa) and benign prostatic hyperplasia (BPH) patients as well as healthy volunteers, we found that 320 and 600 ng/mL tPSMA could be recommended as the threshold values to differentiate BPH from PCa and for the diagnosis of PCa. Moreover, PSMA-positive circulating tumor cells (CTCs) were counted using ICPMS being from 134 to 773 CTCs in the PCa blood samples of the Gleason score from 6 to 9 when the cell membrane-spanning mPSMA was tagged. Such a methodology developed could be expected to be applicable to other clinic-meaningful biomolecules and their host CTCs in liquid biopsy, when other specific targeting groups are modified to the NIR Nd tag.

  9. Neodymium Isotopes and REE pattern in seawater of the tropical Atlantic Ocean

    NASA Astrophysics Data System (ADS)

    Zieringer, M.; Frank, M.; Hathorne, E. C.

    2012-12-01

    Neodymium (Nd) isotopes and rare earth element (REE) patterns are used as tracers of present day ocean circulation and to fingerprint source materials. We present full water column Nd isotopic compositions and dissolved REE distributions in seawater of the tropical Atlantic Ocean. Samples were collected during the GEOTRACES expedition A11 (R/V Meteor) from Las Palmas (Canary Islands) to Port of Spain (Trinidad and Tobago). Highly variable REE concentrations and associated REE patterns in surface waters can be grouped into different oceanic provinces and reflect prominent local source provenances like volcanic islands and dust particles of continental origin. Generally, concentrations in the eastern basin, especially in the vicinity of the Canary Islands and off the coast of NW Africa, are higher than in the western basin. In the area of the Canary Islands shale-normalized REE pattern are characterized by a strong increase in concentrations of the heavy REE relative to the light REE, while south of it REE pattern are almost flat. Nd concentrations in surface waters range between a minimum of 14 pmol/kg in surface waters with reduced salinities (< 33.6 psu) due to freshwater input by the Amazon river and a maximum off the coast of NW Africa that provides evidence of inputs from partial dissolution of dust from the Sahara desert region and from ocean island wheathering. This is also reflected in the Nd isotopic composition, which ranges from ɛNd = - 12.7 to - 8.8. The most radiogenic values are measured between Tenerife and Grand Canary (ɛNd = - 8.8), while the Nd isotopic composition is least radiogenic in the open ocean surface waters. In addition to the surface waters we will present full water column profiles including samples from all major water masses that are present in the tropical Atlantic Ocean. The isotopic distribution of Nd together with the REE distribution in intermediate and deep waters provides information on water mass mixing and water

  10. Authigenic oxide Neodymium Isotopic composition as a proxy of seawater: applying multivariate statistical analyses.

    NASA Astrophysics Data System (ADS)

    McKinley, C. C.; Scudder, R.; Thomas, D. J.

    2016-12-01

    The Neodymium Isotopic composition (Nd IC) of oxide coatings has been applied as a tracer of water mass composition and used to address fundamental questions about past ocean conditions. The leached authigenic oxide coating from marine sediment is widely assumed to reflect the dissolved trace metal composition of the bottom water interacting with sediment at the seafloor. However, recent studies have shown that readily reducible sediment components, in addition to trace metal fluxes from the pore water, are incorporated into the bottom water, influencing the trace metal composition of leached oxide coatings. This challenges the prevailing application of the authigenic oxide Nd IC as a proxy of seawater composition. Therefore, it is important to identify the component end-members that create sediments of different lithology and determine if, or how they might contribute to the Nd IC of oxide coatings. To investigate lithologic influence on the results of sequential leaching, we selected two sites with complete bulk sediment statistical characterization. Site U1370 in the South Pacific Gyre, is predominantly composed of Rhyolite ( 60%) and has a distinguishable ( 10%) Fe-Mn Oxyhydroxide component (Dunlea et al., 2015). Site 1149 near the Izu-Bonin-Arc is predominantly composed of dispersed ash ( 20-50%) and eolian dust from Asia ( 50-80%) (Scudder et al., 2014). We perform a two-step leaching procedure: a 14 mL of 0.02 M hydroxylamine hydrochloride (HH) in 20% acetic acid buffered to a pH 4 for one hour, targeting metals bound to Fe- and Mn- oxides fractions, and a second HH leach for 12 hours, designed to remove any remaining oxides from the residual component. We analyze all three resulting fractions for a large suite of major, trace and rare earth elements, a sub-set of the samples are also analyzed for Nd IC. We use multivariate statistical analyses of the resulting geochemical data to identify how each component of the sediment partitions across the sequential

  11. Neodymium diffusion in orthopyroxene: Experimental studies and applications to geological and planetary problems

    NASA Astrophysics Data System (ADS)

    Sano, Jennifer; Ganguly, Jibamitra; Hervig, Richard; Dohmen, Ralf; Zhang, Xiaoyu

    2011-08-01

    resetting of the Sm-Nd mineral age by an "impulsive disturbance" [Prinzhoffer A, Papanastassiou D.A, Wasserburg G.J., 1992. Samarium-neodymium evolution of meteorites. Geochim. Cosmochim. Acta 56, 797-815].

  12. 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

  13. Neodymium isotopes in biogenic carbonates: reliable archives of ɛNd

    NASA Astrophysics Data System (ADS)

    Montagna, P.; Goldstein, S. L.; Taviani, M.; Frank, N.; McCulloch, M. T.

    2010-12-01

    Neodymium isotope (143Nd/144Nd) compositions from dispersed authigenic ferromanganese oxide fraction in marine sediments, ferromanganese crusts, foraminiferal shells and fossil fish teeth are employed to trace provenance and water mass mixing in the past, having the advantage of not being fractionated by biological processes in the water column. In the modern ocean the different water masses ultimately derive their ɛNd values through continental weathering, erosion and particle-seawater interactions. This geochemical tracer has been only recently applied to scleractinian deep-water coral skeletons sourced from various sites and depths in the Atlantic ocean. Aragonitic corals can be precisely dated by U-series, potentially providing century-long records of intermediate and bathyal zone variability at sub-decadal resolution. Motivated by these recent findings we have investigated the Nd isotopic compositions of living specimens of various calcifying organisms collected in two key locations of the Mediterranean Sea and in the Southern Ocean. In particular, we analyzed several specimens of the aragonitic deep-water corals Desmophyllum dianthus, Lophelia pertusa, Madrepora oculata, Flabellum impensum, the temperate coral Cladocora caespitosa, the calcitic gorgonian coral Corallium rubrum, the bivalves Glans aculeata and Karnekampia bruei and the polychate Serpula vermicularis. Most of the samples were retrieved from the Strait of Sicily and the Southern Adriatic Sea at different water depths. Ten seawater samples from three new profiles in the Mediterranean were also collected at the same locations and depths, offering a unique opportunity to compare the Nd isotopic composition of biogenic carbonates directly with the surrounding ambient seawater. The Mediterranean Sea is particularly suited for this comparison exercise since it is characterized by water masses displaying a large range of ɛNd values, from -10.5 in the Western Mediterranean to -4.8 in the Eastern

  14. Enantiomeric NMR signal separation behavior and mechanism of samarium(III) and neodymium(III) complexes with (S,S)-ethylenediamine-N,N'-disuccinate.

    PubMed

    Aizawa, Sen-Ichi; Okano, Masaru; Kidani, Takahiro

    2017-04-12

    Enantiomeric (1) H and (13) C NMR signal separation behaviors of various α-amino acids and DL-tartarate were investigated by using the samarium(III) and neodymium(III) complexes with (S,S)-ethylenediamine-N,N'-disuccinate as chiral shift reagents. A relatively smaller concentration ratio of the lanthanide(III) complex to substrates was suitable for the neodymium(III) complex compared with the samarium(III) one, striking a balance between relatively greater signal separation and broadening. To clarify the difference in the signal separation behavior, the chemical shifts of β-protons for fully bound D- and L-alanine (δb (D) and δb (L)) and their adduct formation constants (Ks) were obtained for both metal complexes. Preference for D-alanine was similarly observed for both complexes, while it was revealed that the difference between the δb (D) and δb (L) values is the significant factor to determine the enantiomeric signal separation. The neodymium(III) and samarium(III) complexes can be used complementarily for higher and smaller concentration ranges of substrates, respectively, because the neodymium(III) complex gives the larger difference between the δb (D) and δb (L) values with greater signal broadening compared to the samarium(III) complex.

  15. From the subtropics to the equator in the Southwest Pacific: Continental material fluxes quantified using neodymium data along modeled thermocline water pathways

    NASA Astrophysics Data System (ADS)

    Grenier, Mélanie; Jeandel, Catherine; Cravatte, Sophie

    2014-06-01

    The southwestern tropical Pacific, part of a major pathway for waters feeding the Equatorial Undercurrent, is a region of important geochemical enrichment through land-ocean boundary exchange. Here we develop an original method based on the coupling between dynamical modeling and geochemical tracer data to identify regions of enrichment along the water pathways from the subtropics to the equator, and to allow a refined quantification of continental material fluxes. Neodymium data are interpreted with the help of modeled Lagrangian trajectories of an Ocean General Circulation Model. We reveal that upper and lower thermocline waters have different pathways together with different geochemical evolutions. The upper thermocline waters entering the Solomon Sea mainly originate from the central subtropical gyre, enter the Coral Sea in the North Vanuatu Jet and likely receive radiogenic neodymium from the basaltic island margins encountered along their route. The lower thermocline waters entering the Solomon Sea mainly originate from northeast of New Zealand and enter the Coral Sea in the North Caledonian Jet. Depletion of their neodymium content likely occurs when flowing along the Australian and Papua coasts. Downstream from the Solomon Sea, waters flowing along the Papua New Guinea margins near the Sepik river mouth become surprisingly depleted in their neodymium content in the upper thermocline while enriched in the lower thermocline. This coupled approach is proposed as strong support to interpret the origin of the equatorial Pacific natural fertilization through a better understanding of the circulation, important objectives of the international GEOTRACES and SPICE programs, respectively.

  16. Effect of silicate structure on thermodynamic properties of calcium silicate melts: Quantitative analysis of Raman spectra

    NASA Astrophysics Data System (ADS)

    Park, Joo Hyun

    2013-05-01

    The distribution of silicate anionic species (Qn units, n=0, 1, 2, 3) and the chemical speciation of oxygen in CaO-SiO2-MO (M=Mn and Mg) slags were investigated by micro-Raman spectroscopic analysis. Furthermore, the thermochemical properties were evaluated using a concentration of free oxygen and a degree of polymerization. A good linear relationship was obtained between sulfide capacity and concentration of free oxygen in the CaO-SiO2 (-MnO) melts at 1500 to 1600 °C. However, even though there was more abundant free oxygen in the CaO-SiO2-MgO system than in the CaO-SiO2 system, the sulfide capacity of the former was lower than the latter, indicating that the sulfur dissolution behavior in the silicate melts cannot be simply explained by the content of free oxygen, because the composition dependency of the stability ratio of oxygen and sulfide ions should be taken into account. The excess free energy of CaO, MgO and MnO linearly decreased as the ln (Q3/Q2) increased. The effect of the degree of polymerization on the excess free energy of mixing of MgO-containing slag was larger than that of MnO-containing slag, which was explained by the difference of the ionization potential between Mn2+ and Mg2+ ions.

  17. The extent of disorder and properties of silicate glasses, melts and layer-silicates: Spectroscopic analysis and quantum chemical calculations

    NASA Astrophysics Data System (ADS)

    Lee, Sung Keun

    Silicate glasses and melts have long been studied not only because of their geologic relevance to natural magmas but also because of their technological applications to the glass industry. The inherent aspect of silicate glasses and melts are extent of disorder among framework units and the distribution of internal structural variables. This dissertation is for a systematic exploration of the extent of disorder in silicate glasses, melts and layer-silicates using NMR spectroscopy and analysis both by theoretical prediction based on statistical thermodynamics and by quantum chemical calculations. The objective of the dissertation includes exploration of the consequences of the degree of disorder of the system on physical properties of interest to geologists and material scientists. The degree of randomness in framework in silicate glasses including borosilicate and aluminosilicates was quantified using the models introducing order parameters such as the degree of Al avoidance and the degree of inter-mixing. The model in conjunction with input from high-resolution NMR and quantum chemical calculations was used to calculate the configurational thermodynamic properties in these glasses. We presented general framework for understanding the extent of short-range order in framework silicates, demonstrating that a more complete description of the macroscopic thermodynamic properties of silicates can be derived from information on the degree of framework disorder and provides another strong link between structures of melts and properties. Bond angle and length distributions, one aspect of topological disorder in this system, were also quantified using these methods. 17O MQ (multiple quantum) MAS NMR at high fields were applied to better understand reactivity of oxygen sites in layer silicates which are one of the most dominant constituents of the Earth's surfaces. Several basal and apical oxygen sites in model clay minerals were resolved, providing improved prospects for

  18. Partitioning coefficients between olivine and silicate melts

    NASA Astrophysics Data System (ADS)

    Bédard, J. H.

    2005-08-01

    Variation of Nernst partition coefficients ( D) between olivine and silicate melts cannot be neglected when modeling partial melting and fractional crystallization. Published natural and experimental olivine/liquidD data were examined for covariation with pressure, temperature, olivine forsterite content, and melt SiO 2, H 2O, MgO and MgO/MgO + FeO total. Values of olivine/liquidD generally increase with decreasing temperature and melt MgO content, and with increasing melt SiO 2 content, but generally show poor correlations with other variables. Multi-element olivine/liquidD profiles calculated from regressions of D REE-Sc-Y vs. melt MgO content are compared to results of the Lattice Strain Model to link melt MgO and: D0 (the strain compensated partition coefficient), EM3+ (Young's Modulus), and r0 (the size of the M site). Ln D0 varies linearly with Ln MgO in the melt; EM3+ varies linearly with melt MgO, with a dog-leg at ca. 1.5% MgO; and r0 remains constant at 0.807 Å. These equations are then used to calculate olivine/liquidD for these elements using the Lattice Strain Model. These empirical parameterizations of olivine/liquidD variations yield results comparable to experimental or natural partitioning data, and can easily be integrated into existing trace element modeling algorithms. The olivine/liquidD data suggest that basaltic melts in equilibrium with pure olivine may acquire small negative Ta-Hf-Zr-Ti anomalies, but that negative Nb anomalies are unlikely to develop. Misfits between results of the Lattice Strain Model and most light rare earth and large ion lithophile partitioning data suggest that kinetic effects may limit the lower value of D for extremely incompatible elements in natural situations characterized by high cooling/crystallization rates.

  19. Viscoelastic properties of polymer based layered-silicate nanocomposites

    NASA Astrophysics Data System (ADS)

    Ren, Jiaxiang

    Polymer based layered-silicate nanocomposites offer the potential for dramatically improved mechanical, thermal, and barrier properties while keeping the material density low. Understanding the linear and non-linear viscoelastic response for such materials is crucial because of the ability of such measurements to elucidate the mesoscale dispersion of layered-silicates and changes in such dispersion to applied flows as would be encountered in processing of these materials. A series of intercalated polystyrene (and derivatives of polystyrene) layered-silicate nanocomposites are studied to demonstrate the influence of mesoscale dispersion and organic---inorganic interactions on the linear and non-linear viscoelastic properties. A layered-silicate network structure is exhibited for the nanocomposites with strong polymer-silicate interaction such as montmorillonite (2C18M) and fluorohectorite (C18F) and the percolation threshold is ˜ 6 wt % for the 2C18M based hybrids. However, the nanocomposites based on hectorite (2C18H) with weak polymer-silicate interaction exhibit liquid-like terminal zone behavior. Furthermore, the enhanced terminal zone elastic modulus and viscosity of high brominated polystyrene and high molecular weight polystyrene based 2C18M nanocomposites suggest an improved delamination and dispersion of layered-silicates in the polymer matrix. The non-linear viscoelastic properties, specifically, the non-linear stress relaxation behavior and the applicability of time---strain separability, the effect of increasing strain amplitude on the oscillatory shear flow properties, and the shear rate dependence of the steady shear flow properties are examined. The silicate sheets (or collections of sheets) exhibit the ability to be oriented by the applied flow. Experimentally, the empirical Cox - Merz rule is demonstrated to be inapplicable for the hybrids. Furthermore, the K-BKZ constitutive model is used to model the steady shear properties. While being able to

  20. Subpicosecond pulses from a neodymium-glass laser with a solid-liquid phototropic shutter

    NASA Astrophysics Data System (ADS)

    Altshuler, G. B.; Dulneva, E. G.; Karasev, V. B.; Okishev, A. V.; Telegin, L. S.

    1985-02-01

    Subpicosecond, spectrally limited pulses were generated in a mode-locked silicate-Nd-glass laser by means of a phototropic shutter. The shutter featured molecules of an organic dye added to a matrix composed of an isobutyl alcohol-filled quartz micropore glass plate. A coating on the inner surface of one of the cell windows was 0.99 reflective at the lasing wavelength. Single pulses with 0.5-1 psec length were generated, validating the use of a solid-liquid shutter for producing subpicosecond pulses with a Nd-glass laser. Furthermore, the liquid component permitted output powers of up to 5 W/sq cm without eliciting thermooptical effects.

  1. Molecular Diffusivities of Silicic and Gernamic Acids in Aqueous Solutions

    NASA Astrophysics Data System (ADS)

    Cummins, K. M.; Hammond, D. E.

    2001-12-01

    Germanium and silicon have many similarities in their water column behaviors, but these elements may be fractionated by diagenetic reactions in iron-rich, reducing sediments. Pore water profiles can constrain the magnitude of this fractionation, but diffusion coefficients for both silicic and germanic acid are required to quantitatively determine their transport. The objective of this study was to experimentally determine these diffusivities, using a diaphragm cell in the laboratory. A porous frit was filled with solutions containing KCl, silicic acid, and germanic acid (as a 68Ge tracer). These solutes were allowed to diffuse into a reservoir of well-mixed deionized water at 25 C. Samples were drawn from the reservoir over time, and a numerical simulation was used to estimate the diffusivity required to best fit the resulting concentration change over a 4-6 day period. Results (in 10e-6 cm2 s-1) for silicic acid averaged 8.86 +/- 0.42 and 7.83 +/- 0.66 for silicic acid concentrations of 350 uM and 910 uM respectively. These are significantly smaller than previously published results of Applin (1987), but show a similar dependence on silicic acid concentration. These results in fresh water are comparable to results of Wollast and Garrels (1970) in sea water. Results for germanic acid averaged 8.92 +/- 0.82, indistinguishable from results for silicic acid, and they did not exhibit a strong dependence on the silicic acid concentration. Additional experiments are underway using a sea water medium.

  2. Comment on "The shape and composition of interstellar silicate grains"

    SciTech Connect

    Bradley, J P; Ishii, H

    2007-09-27

    In the paper entitled 'The shape and composition of interstellar silicate grains' (A & A, 462, 667-676 (2007)), Min et al. explore non-spherical grain shape and composition in modeling the interstellar 10 and 20 {micro}m extinction features. This progression towards more realistic models is vitally important to enabling valid comparisons between dust observations and laboratory measurements. Min et al. proceed to compare their model results with GEMS (glass with embedded metals and sulfides) from IDPs (interplanetary dust particles) and to discuss the nature and origin of GEMS. Specifically, they evaluate the hypothesis of Bradley (1994) that GEMS are interstellar (IS) amorphous silicates. From a comparison of the mineralogy, chemical compositions, and infrared (IR) spectral properties of GEMS with their modeling results, Min et al. conclude: 'GEMS are, in general, not unprocessed leftovers from the diffuse ISM'. This conclusion is based, however, on erroneous and incomplete GEMS data. It is important to clarify first that Bradley (1994) never proposed that GEMS are unprocessed leftovers from the diffuse ISM, nor did he suggest that individual subnanogram mass GEMS are a representative sampling of the enormous mass of silicates in the diffuse ISM. Bradley (1994) simply showed that GEMS properties are consistent with those of IS amorphous silicates. It is widely accepted that circumstellar outflows are important sources of IS silicates, and whether GEMS are processed or not, the circumstellar heritage of some has been rigorously confirmed through measurements of non-solar oxygen (O) isotope abundances (Messenger et al., 2003; Floss et al., 2006). Keller et al. (2000) assert that even GEMS without detectable O isotope anomalies are probably also extrasolar IS silicates because they are embedded in carbonaceous material with non-solar D/H isotopic composition. (Much of the silicate dust in the ISM may be isotopically homogenized (Zhukovska et al., 2007)). Recent

  3. Behavior of Np(VII, VI, V) in Silicate Solutions

    SciTech Connect

    Shilov, V P.; Fedoseev, A M.; Yusov, A B.; Delegard, Calvin H.

    2004-11-30

    Spectrophotometric methods were used to investigate the properties of neptunium(VII), (VI), and (V) in silicate solution. The transition of cationic neptunium(VII) to anionic species in non-complexing environments proceeds in the range of ?? 5.5 to 7.5. In the presence of carbonate, this transition occurs at ?? 10.0 to 11.5 and in silicate solutions at ?? 10.5-12.0. These findings show that cationic neptunium(VII) forms complexes with both carbonate and silicate and that the silicate complex is stronger than that of the carbonate. The competition of complex formation reactions for neptunium(VI) with carbonate and silicate and on the known complex stability constant of NpO2(CO3)34- allowed the NpO2SiO3 complex stability constant, log ? = 16.5, to be estimated. Determination of the formation constant of Np(V) complexes with SiO32- was not possible using similar methods.

  4. Preparation and Insulation Properties of Epoxy-Layered Silicate Nanocomposite

    NASA Astrophysics Data System (ADS)

    Imai, Takahiro; Sawa, Fumio; Ozaki, Tamon; Nakano, Toshiyuki; Shimizu, Toshio; Yoshimitsu, Tetsuo

    Recent rapid progress in nanotechnology has focused research and development efforts on new high performance materials. Organic-inorganic hybrid materials such as nylon-layered silicate nanocomposites have attracted special interest and various studies continue to be conducted on thermoplastic resins. In this study, we found out the best organic modifier of layered silicate that contributed to an affinity for epoxy resin (thermosetting resin), and succeeded in creating an intercalated-type epoxy-layered silicate nanocomposite. This nanocomposite realized some improvements by the addition of 5 or 6 weight percentage of organically modified layered silicates, which have 20oC higher thermal resistance, 60% higher fracture toughness, 19% higher flexural strength and 10% higher insulation breakdown strength than these of an epoxy resin without layered silicate fillers. An electrical treeing growth was observed in the nanocomposite. The electrical treeing progress with many branches in the nanocomposite seemed to result in an increase in the insulation breakdown strength. These results suggest the possibility of practical use as an insulating material in heavy apparatuses.

  5. Heterogeneous Nucleation of Protein Crystals on Fluorinated Layered Silicate

    PubMed Central

    Ino, Keita; Udagawa, Itsumi; Iwabata, Kazuki; Takakusagi, Yoichi; Kubota, Munehiro; Kurosaka, Keiichi; Arai, Kazuhito; Seki, Yasutaka; Nogawa, Masaya; Tsunoda, Tatsuo; Mizukami, Fujio; Taguchi, Hayao; Sakaguchi, Kengo

    2011-01-01

    Here, we describe an improved system for protein crystallization based on heterogeneous nucleation using fluorinated layered silicate. In addition, we also investigated the mechanism of nucleation on the silicate surface. Crystallization of lysozyme using silicates with different chemical compositions indicated that fluorosilicates promoted nucleation whereas the silicates without fluorine did not. The use of synthesized saponites for lysozyme crystallization confirmed that the substitution of hydroxyl groups contained in the lamellae structure for fluorine atoms is responsible for the nucleation-inducing property of the nucleant. Crystallization of twelve proteins with a wide range of pI values revealed that the nucleation promoting effect of the saponites tended to increase with increased substitution rate. Furthermore, the saponite with the highest fluorine content promoted nucleation in all the test proteins regardless of their overall net charge. Adsorption experiments of proteins on the saponites confirmed that the density of adsorbed molecules increased according to the substitution rate, thereby explaining the heterogeneous nucleation on the silicate surface. PMID:21818343

  6. Properties of cometary crystalline silicate before and after perihelion passage

    NASA Astrophysics Data System (ADS)

    Ootsubo, Takafumi

    2013-01-01

    Crystalline silicate is sometimes observed in comets as an 11.3-micron resonant emission feature, and may be used for probing the early solar nebula. Because the formation of the crystalline silicate requires high temperature, they are thought to be born from amorphous silicate at the inner region, and then transported toward the outer regions where comets were born. This transportation can produce the difference in the crystalline fraction in the cometary silicate dust between two dynamical types of comets, Oort-cloud comets (OCs) and Ecliptic comets (ECs), due to the different heliocentric distances of their birth places. The study of peak wavelengths in crystalline features is important to investigate the conditions of the crystalline silicate formation as well. Thus far, we don't have enough OC samples, while we have observed several ECs. Fortunately, we can observe three comets in this semester. In particular, C/2012 S1 (ISON) is a bright sungrazing comet, and we might expect possible splitting and exposing of pristine materials inside the nucleus after its perihelion passage. Observations at pre- and post-perihelion provide us precious information on the dust evolution of the comet. The comet C/2012 S1 (ISON), along with two other comets, is an unparalleled target for this study.

  7. Neodymium and carbon isotopic fingerprints of warm Pliocene circulation throughout the deep Atlantic

    NASA Astrophysics Data System (ADS)

    Riesselman, C. R.; Scher, H. D.; Dowsett, H. J.; Robinson, M. M.

    2013-12-01

    The mid-Piacenzian age of the Pliocene is the most recent interval in Earth's history to sustain global warmth within the range predicted for the 21st century. To understand this interval, the USGS PRISM Project has developed a reconstruction of global conditions at 3.264-3.025 Ma, which includes a significant North Atlantic warm SST anomaly coupled with increased evaporation. Warm anomalies are also detected in the deep ocean as far as 46°S, suggesting that enhanced meridional overturning circulation may have been responsible for more southerly penetration of North Atlantic Deep Water (NADW). However, deep 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 synthesis of Atlantic deep ocean circulation during the PRISM interval, using the neodymium isotopic composition (ɛNd) of fossil fish teeth as a proxy for water mass source and the δ13C of benthic foraminifera as a proxy for water mass age. This reconstruction utilizes both new and previously published data from 11 DSDP and ODP sites in the North Atlantic (Site 610) and along depth transects from equatorial Ceara Rise, southern mid-latitude Walvis Ridge, and south Atlantic Meteor Rise/Agulhas Ridge. Published data from ferromanganese crusts constrain Pliocene Antarctic deep waters at ~ ɛNd = -8, distinct from the less radiogenic ɛNd = -11.5 that characterizes Pliocene northern component water (NCW). These values fingerprint northern and southern sources throughout the Atlantic basin. Pliocene fish teeth from Site 610 (2400 m water depth) and from four Ceara Rise sites (3000-4300 m) preserve distinctly North Atlantic ɛNd. When averaged across the PRISM interval, mean values for these five sites range from ɛNd = -10.97 to -10.25, and the Pliocene depth transect closely mirrors the structure of the modern column, indicating

  8. Scheelite-type sodium neodymium(III) ortho-oxidomolybdate(VI), NaNd[MoO(4)](2).

    PubMed

    Schleid, Thomas; Hartenbach, Ingo

    2011-12-01

    Scheelite-type NaNd[MoO(4)](2) contains one crystallographic position (site symmetry [Formula: see text]) for the large cations, which is mixed-occupied by Na(+) and Nd(3+) cations in a 1:1 molar ratio. Thus, both are surrounded by eight O atoms in the shape of a trigonal dodeca-hedron. Furthermore, the structure consists of crystallographically unique [MoO(4)](2-) units (site symmetry [Formula: see text]) surrounded by eight sodium and neodymium cations, which are all vertex-attached. The polyhedra around the Na(+)/Nd(3+) cations are connected to four others via common edges, building up a three-dimensional network in whose tetra-hedral voids of O atoms the Mo(6+) cations reside.

  9. From electrocautery, balloon dilatation, neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser to argon plasma coagulation and cryotherapy

    PubMed Central

    Pickering, Edward M.; Lee, Hans J.

    2015-01-01

    Over the past decade, there has been significant advancement in the development/application of therapeutics in thoracic diseases. Ablation methods using heat or cold energy in the airway is safe and effective for treating complex airway disorders including malignant and non-malignant central airway obstruction (CAO) without limiting the impact of future definitive therapy. Timely and efficient use of endobronchial ablative therapies combined with mechanical debridement or stent placement results in immediate relief of dyspnea for CAO. Therapeutic modalities reviewed in this article including electrocautery, balloon dilation (BD), neodymium-doped:yttrium-aluminum-garnet (Nd:YAG) laser, argon plasma coagulation (APC), and cryotherapy are often combined to achieve the desired results. This review aims to provide a clinically oriented review of these technologies in the modern era of interventional pulmonology (IP). PMID:26807284

  10. Thermo-optic characterization of neodymium/nickel doped silica glasses prepared via sol-gel route.

    PubMed

    Manuel, Ancy; Kumar, B Rajesh; Basheer, N Shemeena; Kumari, B Syamala; Paulose, P I; Kurian, Achamma; George, Sajan D

    2012-12-01

    Intrinsic as well as rare earth (Neodymium) doped silica glasses with various molar ratio of dopant and a metallic (Nickel) co-dopant is prepared via sol-gel route. The structural characterization of the sample is carried out using X-ray diffraction and Fourier Transform Infrared Spectroscopy. The influence of dopant and doping concentration on the optical properties of silica matrix is investigated via UV-VIS absorption spectroscopy. Effect of dopant on thermal effusivity value of the host matrix is carried out by laser induced open cell photoacoustic technique. Analysis of the results showed that doping affect the thermal effusivity value and results are interpreted in terms of structural modification of the lattice and phonon assisted heat transport mechanism.

  11. Value analysis of neodymium content in shredder feed: toward enabling the feasibility of rare earth magnet recycling.

    PubMed

    Bandara, H M Dhammika; Darcy, Julia W; Apelian, Diran; Emmert, Marion H

    2014-06-17

    In order to facilitate the development of recycling technologies for rare earth magnets from postconsumer products, we present herein an analysis of the neodymium (Nd) content in shredder scrap. This waste stream has been chosen on the basis of current business practices for the recycling of steel, aluminum, and copper from cars and household appliances, which contain significant amounts of rare earth magnets. Using approximations based on literature data, we have calculated the average Nd content in the ferrous shredder product stream to be between 0.13 and 0.29 kg per ton of ferrous scrap. A value analysis considering rare earth metal prices between 2002 and 2013 provides values between $1.32 and $145 per ton of ferrous scrap for this material, if recoverable as pure Nd metal. Furthermore, we present an analysis of the content and value of other rare earths (Pr, Dy, Tb).

  12. Structure of fluorite-like compound based on Nd₅Mo₃O₁₆ with lead partly substituting for neodymium.

    PubMed

    Antipin, Alexander M; Sorokina, Natalia I; Alekseeva, Olga A; Kuskova, Alexandra N; Kharitonova, Elena P; Orlova, Ekaterina I; Voronkova, Valentina I

    2015-04-01

    A single crystal of Nd5Mo3O16 with lead partly substituting for neodymium, which has a fluorite-like structure, was studied by precision X-ray diffraction, high-resolution transmission microscopy and EDX microanalysis. The crystal structure is determined in the space group Pn3¯n. It was found that the Pb atoms substitute in part for Nd atoms in the structure and are located in the vicinity of Nd2 positions. Partial substitutions of Mo cations for Nd positions and of Nd for Mo positions in crystals of the Ln5Mo3O16 oxide family are corroborated by X-ray diffraction for the first time. The first experimental verification of the location of an additional oxygen ion in the voids abutting MoO4 tetrahedra was obtained.

  13. Dislocation of polyfocal full-optics accommodative intraocular lens after neodymium-doped yttrium aluminum garnet capsulotomy in vitrectomized eye.

    PubMed

    Kang, Kyung Tae; Kim, Yu Cheol

    2013-11-01

    We report a case of dislocation of WIOL-CF® polyfocal full-optics intraocular lens (IOL) after neodymium-doped yttrium aluminum garnet (Nd: YAG) laser capsulotomy in the vitrectomized eye. At 22 months before the dislocation of the IOL, a 55-year-old male patient underwent phacoemulsification with WIOL-CF® IOL implantation in a local clinic and 10 months after the cataract surgery the patient underwent pars plana vitrectomy, endolaser photocoagulation and 14% C 3 F 8 gas tamponade for the treatment of rhegmatogenous retinal detachment. At 9 months after the vitrectomy, the patient visited our clinic for a sudden decrease of vision after Nd: YAG capsulotomy in the local clinic. On fundus examination, the dislocated IOL was identified and the Nd: YAG capsulotomy site and the larger break, which is suspected to have been a route of the dislocation were observed in the posterior capsule.

  14. Effects of neodymium:yttrium aluminum garnet laser irradiation on endometrium and on endometrial cysts in six mares.

    PubMed

    Blikslager, A T; Tate, L P; Weinstock, D

    1993-01-01

    Effects of neodymium:yttrium aluminum garnet (Nd:YAG) laser irradiation on equine endometrium were evaluated in vitro and in six mares with endometrial cysts. The Nd:YAG laser was applied to six endometrial sites, in each of five uterine specimens, with power densities of 5659 to 33,954 J/cm2. Depth of tissue ablation was measured and graded on histologic sections of the tissue lesions. Power density had a significant effect on the depth of tissue ablation (p < .001). Grade 3 lesions (full-thickness ablation of the endometrium) were created with energy densities of 16,977 to 33,954 J/cm2. Six mares had endometrial cysts treated by photoablation. Two of the four mares that were reproductively sound but barren, despite appropriate breeding, produced foals after treatment. One mare remained reproductively unsound after treatment, and another mare that was treated postpartum was bred successfully.

  15. Longitudinal Spin Seebeck Effect in Bi-substituted Neodymium Iron Garnet on Gadolinium Gallium Garnet Substrate Prepared by MOD Method

    NASA Astrophysics Data System (ADS)

    Asada, H.; Kuwahara, A.; Sueyasu, K.; Ishibashi, T.; Liu, Q.; Lou, G.; Kishimoto, K.; Koyanagi, T.

    Bi-substituted Neodymium Iron Garnet (Nd3-xBixFe5O12, Bi:NIG) thin films with the Bi composition x=0-1.0 are prepared on both the (001) and (111) oriented gadolinium gallium garnet (GGG) substrates by a metal organic decomposition method. Crystalline qualities and magnetic properties of these films are examined by X-ray diffraction, atomic force microscopy and vibrating sample magnetometer. Longitudinal spin Seebeck effects (LSSEs) are investigated by means of the inverse spin Hall effect in a Pt film. The increase of LSSE voltage in Bi:NIG(x=0-1.0)/Pt bilayers on GGG(001) is observed with the increase of Bi composition. In the case of GGG(111), the LSSE voltage for Bi:NIG(x=1.0) is also larger than that for NIG.

  16. Activation cross-sections of deuteron induced nuclear reactions on neodymium up to 50 MeV

    NASA Astrophysics Data System (ADS)

    Tárkányi, F.; Takács, S.; Ditrói, F.; Hermanne, A.; Yamazaki, H.; Baba, M.; Mohammadi, A.; Ignatyuk, A. V.

    2014-04-01

    In the frame of a systematic study of activation cross sections of deuteron induced nuclear reactions on rare earths, the reactions on neodymium for production of therapeutic radionuclides were measured for the first time. The excitation functions of the natNd(d,x) 151,150,149,148m,148g,146,144,143Pm, 149,147,139mNd, 142Pr and 139gCe nuclear reactions were assessed by using the stacked foil activation technique and high resolution γ-spectrometry. The experimental excitation functions were compared to the theoretical predictions calculated with the modified model codes ALICE-IPPE-D and EMPIRE-II-D and with the data in the TENDL-2012 library based on latest version of the TALYS code. The application of the data in the field of medical isotope production and nuclear reaction theory is discussed.

  17. Covariation of deglacial North Pacific intermediate water ventilation and atmospheric CO2 evidenced by authigenic neodymium isotope composition

    NASA Astrophysics Data System (ADS)

    Du, J.; Haley, B. A.; Mix, A. C.

    2016-12-01

    The role of the North Pacific in the global carbon cycle during the last deglaciation remains unclear, largely because of the lack of suitable sedimentary archives. The neodymium isotope composition (ɛNd) of authigenic phases has been widely used as a watermass tracer in paleoceanography, but the foundation of this application remains uncertain because the diagenetic cycle of neodymium is poorly understood. Recently we examined the relationship of ɛNd among bottom water, pore water, authigenic phase and detrital sediment, and concluded that authigenic phases record the ɛNd of pore water, not bottom water. In light of this new development, we proposed that the deviation of authigenic ɛNd from detrital ɛNd could be used as a proxy for bottom water residence time on seafloor and by inference ocean ventilation rate. Here, we present new high resolution authigenic and detrital ɛNd records from an intermediate water site (EW0408-85JC, 682 m) in the Gulf of Alaska. Our results show that during Heinrich 1 and Younger Dryas the ɛNd of authigenic phases diverged from detrital sediments, corresponding to the peak rates of atmospheric CO2 increase. In contrast, during the Bolling-Allerod and Preboreal, authigenic ɛNd converged to detrital ɛNd, synchronous with hiatuses of atmospheric CO2 rise. These observations suggest that in the abrupt cooling events of the last deglaciation, better intermediate water ventilation allowed temporal connection between the deep respired carbon pool in the North Pacific and the atmosphere, leading to the rise of CO2, while in the abrupt warming events strong stratification prevented such interaction. Our new data thus reveal the critical role the North Pacific played in deglacial abrupt climate change events.

  18. Thermodynamic Features of the Complexation of Neodymium(III) and Americium(III) by Lactate in Trifluoromethanesulfonate Media.

    SciTech Connect

    Peter R. Zalupski; Leigh R. Martin; Kenneth L. Nash

    2010-10-01

    The protonation of lactate has been studied in a variety of electrolyte solutions using microcalorimetry to reveal a distinct medium influence imposed on the thermochemistry of the investigated equilibrium. The thermochemistry of lactate protonation, when studied directly in 1.0 M sodium lactate, agreed well with the studies performed in trifluoromethanesulfonate (triflate). This thermodynamic agreement suggests that the physical chemistry of lactate in the solutions applicable to the TALSPEAK process – a solvent extraction method for separating trivalent actinides from trivalent lanthanides within the scope of used nuclear fuel processing efforts – may be simulated in triflate solutions. Potentiometry, spectrophotometry and microcalorimetry have been subsequently used to study the thermodynamic features of neodymium and americium complexation by lactate using triflate as a strong background electrolyte. Three successive mononuclear lactate complexes were identified for Nd(III) and Am(III). The stability constants for neodymium, log ß1 = 2.60 ± 0.01, log ß2 = 4.66 ± 0.02 and log ß3 = 5.6 ± 0.1, and for americium, log ß1 = 2.60 ± 0.06, log ß2 = 4.7 ± 0.1 and log ß3 = 6.2 ± 0.2, were found to closely agree with the thermodynamic studies reported in sodium perchlorate solutions. Consequently, the thermodynamic medium effect, imposed on the TALSPEAK-related solution equilibria by the presence of strong background electrolytes such as NaClO4 and NaNO3, do not significantly impact the speciation in solution.

  19. Influence of the Central American Seaway and Drake Passage on ocean circulation and neodymium isotopes: A model study

    NASA Astrophysics Data System (ADS)

    Pfister, Patrik L.; Stocker, Thomas F.; Rempfer, Johannes; Ritz, Stefan P.

    2014-12-01

    The sensitivity of the neodymium isotopic composition (ɛNd) to tectonic rearrangements of seaways is investigated using an Earth System Model of Intermediate Complexity. The shoaling and closure of the Central American Seaway (CAS) is simulated, as well as the opening and deepening of Drake Passage (DP). Multiple series of equilibrium simulations with various intermediate depths are performed for both seaways, providing insight into ɛNd and circulation responses to progressive throughflow evolutions. Furthermore, the sensitivity of these responses to the Atlantic Meridional Overturning Circulation (AMOC) and the neodymium boundary source is examined. Modeled ɛNd changes are compared to sediment core and ferromanganese (Fe-Mn) crust data. The model results indicate that the North Atlantic ɛNd response to the CAS shoaling is highly dependent on the AMOC state, i.e., on the AMOC strength before the shoaling to shallow depths (preclosure). Three scenarios based on different AMOC forcings are discussed, of which the model-data agreement favors a shallow preclosure (Miocene) AMOC (˜6 Sv). The DP opening causes a rather complex circulation response, resulting in an initial South Atlantic ɛNd decrease preceding a larger increase. This feature may be specific to our model setup, which induces a vigorous CAS throughflow that is strongly anticorrelated to the DP throughflow. In freshwater experiments following the DP deepening, ODP Site 1090 is mainly influenced by AMOC and DP throughflow changes, while ODP Site 689 is more strongly influenced by Southern Ocean Meridional Overturning Circulation and CAS throughflow changes. The boundary source uncertainty is largest for shallow seaways and at shallow sites.

  20. Robustness of fossil fish teeth for seawater neodymium isotope reconstructions under variable redox conditions in an ancient shallow marine setting

    NASA Astrophysics Data System (ADS)

    Huck, Claire E.; van de Flierdt, Tina; Jiménez-Espejo, Francisco J.; Bohaty, Steven M.; Röhl, Ursula; Hammond, Samantha J.

    2016-03-01

    Fossil fish teeth from pelagic open ocean settings are considered a robust archive for preserving the neodymium (Nd) isotopic composition of ancient seawater. However, using fossil fish teeth as an archive to reconstruct seawater Nd isotopic compositions in different sedimentary redox environments and in terrigenous-dominated, shallow marine settings is less proven. To address these uncertainties, fish tooth and sediment samples from a middle Eocene section deposited proximal to the East Antarctic margin at Integrated Ocean Drilling Program Site U1356 were analyzed for major and trace element geochemistry, and Nd isotopes. Major and trace element analyses of the sediments reveal changing redox conditions throughout deposition in a shallow marine environment. However, variations in the Nd isotopic composition and rare earth element (REE) patterns of the associated fish teeth do not correspond to redox changes in the sediments. REE patterns in fish teeth at Site U1356 carry a typical mid-REE-enriched signature. However, a consistently positive Ce anomaly marks a deviation from a pure authigenic origin of REEs to the fish tooth. Neodymium isotopic compositions of cleaned and uncleaned fish teeth fall between modern seawater and local sediments and hence could be authigenic in nature, but could also be influenced by sedimentary fluxes. We conclude that the fossil fish tooth Nd isotope proxy is not sensitive to moderate changes in pore water oxygenation. However, combined studies on sediments, pore waters, fish teeth, and seawater are needed to fully understand processes driving the reconstructed signature from shallow marine sections in proximity to continental sources.